Phosphate homeostasis and its role in bone health

Microalgae for phosphorus chemical wastewater treatment and recovery of phosphorus

In this study, we have found a new method to recovery phosphorus selectively from high-fluoride-phosphoric wastewater. This new method was a microalgae-based phosphorus recovery technology.The results showed that Chlorella sp. can not only grew very well in high-fluoride-phosphoric wastewater, but also has the highest ability to reduce the phosphorus from the wastewater among Scenedesmus sp., Selenastrum bibraianum and Chlamydomonas sp. After Chlorella sp. cultured for 16 days, the concentration of phosphorus decreased from 12.76 mg/L to 5.00 mg/L. There were two ways to reduce phosphorus by Chlorella sp. One was the specific uptakes phosphorus into algal cells and the other was absorbs phosphorus through the functional groups on the EPS. These algal cells can be separated from the wastewater through harvesting or other methods, enabling the subsequent recovery of phosphorus. The results of this study could provide valuable information for phosphorus recovery from high-fluoride-phosphoric wastewater.

Synergistic effects of modified zinc oxide nanoparticle in a hybrid chitosan-gelatin hydrogel for bone regeneration

The development of composite hydrogels with enhanced biocompatibility and osteoconductivity remains a critical focus in bone tissue engineering. In this study, we designed a double-network hydrogel composed of chitosan, and gelatin (CG), crosslinked to improve its mechanical properties for bone regeneration applications. To further enhance its bioactivity, zinc oxide nanoparticles (ZnO) were incorporated into the hydrogel matrix. Prior to incorporation, ZnO was functionalized with a mussel-inspired polydopamine (PDA) coating, forming ZnO/PDA. Subsequently, in situ mineralization facilitated the deposition of calcium and phosphate (CaP) ions, yielding ZnO/PDA/CaP (m-ZnO). To evaluate the effects of these modifications, three hydrogel formulations were prepared: pure CG hydrogel, CG hydrogel containing ZnO/PDA (CG@Z/P), and CG hydrogel incorporated with m-ZnO (CG@m-ZnO). The addition of m-ZnO significantly enhanced the compressive strength of CG@m-ZnO, increasing it from 335.05 ± 8.35 kPa to 973.31 ± 102.19 kPa, while maintaining microstructural integrity. The incorporation of ZnO also imparted antibacterial properties, whereas the PDA and CaP layers promoted cell adhesion and proliferation. Notably, CG@m-ZnO with 50 μg/mL of m-ZnO exhibited excellent biocompatibility and significantly enhanced osteogenic differentiation of MC3T3-E1 cells, as evidenced by increased alkaline phosphate (ALP) activity and Alizarin Red S (ARS) staining. In conclusion, the CG@m-ZnO hydrogel demonstrates a synergistic combination of biocompatibility, osteoconductivity, antibacterial activity, and enhanced mechanical properties, making it a promising candidate for bone tissue engineering and regenerative medicine applications.

Coupling of Intracellular Calcium Homeostasis and Formation and Secretion of Matrix Vesicles: Their Role in the Mechanism of Biomineralization

The human bone is a dynamic, highly vascularized tissue composed of 60-70% minerals, which include mainly calcium phosphate (CaP) in the form of hydroxyapatite (HA) crystals, 30% organic matrix composed of type I collagen fibers, and less than 5% water and lipids. The crystals are formed inside the matrix vesicles (MVs) and are then released in the organic collagen-based fibrous matrix. Extracellular matrix (ECM) formation and mineralization processes, named osteogenesis, are associated with human mesenchymal stem cells (hMSCs) undergoing differentiation into osteoblasts (osteoblastogenesis). Osteogenesis is regulated by multiple intracellular signaling and genetic pathways and by environmental factors. Calcium flow is finely regulated and plays a key role in both osteoblastogenesis and osteogenesis. The formation and accumulation of CaP, the biogenesis of MVs, their secretion, and the deposition of HA crystals to fill the organic bone matrix are the fundamental events in the biomineralization process. In this paper, I will describe and discuss the recent findings and hypothesis on the molecular mechanism regulating this process.

Effect of Inorganic Phosphorus Manipulation on the Growth and Progression of Prostate Cancer Cells In Vitro

Epidemiological studies have linked higher serum and dietary phosphorus to an increased risk of prostate cancer (PC) and its lethal state. However, these findings do not distinguish between the impact of inorganic phosphorus (Pi) per se and the impacts of its homoeostatic regulators. Thus, this study aimed to determine the in vitro tumorigenic effects of elevated Pi concentrations per se on androgen-dependent epithelial-like PLum-AD murine PC cells at molecular and cellular levels. Physiologically attainable elevated levels and supraphysiological levels of sodium (NaPi) and potassium phosphate (KPi) were used to assess PLum-AD cell proliferation, viability, migration, and epithelial-mesenchymal transition (EMT) marker expression, which were determined by the thiazolyl blue tetrazolium bromide cell assay, trypan blue exclusion assay, wound healing assay, and immunofluorescence staining, respectively. Treatment of Plum-AD cells with supraphysiological levels of NaPi (20 mM) significantly reduced cell proliferation, whereas KPi did not, suggesting a potential sodium-dependent Pi uptake mechanism. Furthermore, physiologically relevant elevated concentrations of NaPi (3 mM) and KPi (1 and 3 mM) increased the relative vimentin expression of PLum-AD PC cells, a biomarker of EMT. Our findings suggest that elevated Pi levels per se, in the hyperphosphatemia range, can directly promote EMT in PC, highlighting the potential role of Pi in tumor progression.

Corrosion and Biocompatibility Studies of Bioceramic Alumina Coatings on Aluminum Alloy 6082

Recent advances in ceramic materials, particularly porous alumina (Al2O3), have significantly enhanced the safety and efficacy of medical implants by improving biocompatibility and modulating cellular behavior for biomedical applications. Variations in the surface structure and chemical composition of porous Al2O3 promote different biological responses and coating stability, underscoring the need for further biological and corrosion research. Traditional methods for producing alumina ceramics from powder are expensive, time-consuming, and limited in their ability to create complex shapes and large structures due to the brittleness of alumina. This study evaluates the biocompatibility of bioceramic-coated aluminum (Al) alloy 6082 as a lightweight and cost-effective alternative for bone osteosynthesis plates. Al2O3 coatings were achieved through anodization using phosphoric and sulfuric acids. The untreated and anodized alloys were analyzed for chemical stability and biocompatibility and compared with medical-grade titanium alloy. All specimens exhibited excellent biocompatibility, demonstrating high adhesion and viability of the fibroblast cell line. Corrosion resistance and metal ion release were assessed in simulated body fluid, with all specimens effectively suppressing the release of Fe and toxic Al ions. The untreated Al alloy exhibited a higher release of Mn ions than the coated specimens. Notably, the bioceramic coating obtained in sulfuric acid demonstrated 3 orders of magnitude higher corrosion resistance, indicating its potential suitability for biomedical applications. By addressing the limitations of traditional alumina ceramics, our approach enables the fabrication of products in diverse sizes and shapes, offering a practical solution for creating customized biomedical implants.

Exploring indigenous knowledge and practices of the Gurage community on the biosystematics and utilization of Enset landraces for bone fracture and regeneration: the case of Gurage Zone, central Ethiopia region

Background

Enset (Ensete ventricosum) is a crucial perennial crop in Ethiopia for both food and medicine. The indigenous knowledge and practices of the use and biosystematics of the different Enset landraces are deeply rooted in the community. Enset corms, traditionally used for bone fracture treatment, are rich in phosphorus, potassium, zinc, and calcium supporting bone healing and mineralization. Thus, the study aims to explore the traditional knowledge and practices of the Gurage community regarding Enset folklore biosystematics and the utilization of Enset in bone healing.

Methods

The study utilized semi-structured interviews, focus group discussions, key informant interviews, and field observations to document traditional medicinal uses, cultivation practices, and indigenous biosystematics of Enset in four selected districts or Woredas (Cheha, Ezhe, Enor, and Gumer) of Gurage Zone, Central Ethiopia from 603 respondents. Descriptive statistics were employed for data presentation.

Results

A total of 37 Enset landraces were identified across the study Woredas. Landraces were identified primarily based on leaf and pseudostem color (62%) and size (24.7%). The majority of respondents (57.7%) were knowledgeable about 6-10 Enset landraces, while 21% identified 11-15 varieties. Four landraces Astara (31.3%), Kibinar (22.9%), Dere (22.4%), and Guarye (20.1%)were most commonly used for healing fractured and broken bones. Corms are the major parts of Enset used for healing fractured bones and setting broken bones by mixing them with yogurt, milk, or meat. Enset also serves as livestock fodder (42.3%) and for making household materials (23.3%), with 91.4% cultivated in home gardens. Disease susceptibility, insects, and wild animals were identified as major challenges for Enset production.

Conclusion

Indigenous knowledge has played a significant role in identifying, classifying, and cultivating Enset landraces. Astara, Kibinar, Dere, and Guarye are the most frequently used Enset landraces for healing fractured and broken bones. Further experimental studies to validate the ethnopharmacological uses of Enset for bone healing are highly recommended.

Biomaterials for Guided Tissue Regeneration and Guided Bone Regeneration: A Review

This review aims to provide an overview of the types of membranes, bone substitutes, and mucosal substitutes used for GTR and GBR and briefly explores recent innovations for tissue regeneration and their future perspectives. Since this is a narrative review, no systematic search, meta-analysis, or statistical analysis was conducted. Using biomaterials for GTR and GBR provides a reduction in postoperative morbidity, as it contributes to less invasive clinical procedures, serving as an alternative to autogenous grafts. Moreover, randomized clinical trials (RCTs) and systematic reviews are essential for the evaluation of new biomaterials. These studies provide more robust evidence and help guide clinical practice in the selection of safer and more effective biomaterials, allowing for the personalization of treatment protocols for each patient.

Dynamic ion-releasing biomaterials actively shape the microenvironment to enhance healing

Dynamic ion-releasing biomaterials have redefined the role of implantable bone devices, transitioning them from passive mechanical support to active players in tissue regeneration. These materials actively modulate the surrounding biological microenvironment by releasing bioactive ions (e.g.: calcium, phosphate, and cobalt) which dynamically interact with cells and tissues surrounding them. This interaction becomes the microenvironment highly active and accelerates bone healing, promoting osteogenesis, and enhancing osseointegration. The ions modulate key biological processes in this regard, including osteoblast adhesion, proliferation, differentiation, angiogenesis, and immune responses, as well as coupled physiological mechanisms, ensuring that the implanted biomaterials foster an optimal environment for bone regeneration. More advanced surface modifications onto materials (e.g.: nanostructuring hydroxyapatites coatings) have been shown to further boost ion release, amplifying the ability of the material to influence surrounding tissues. As a result, ion-releasing biomaterials not only improve implant integration but also accelerate the overall healing process. Looking forward, the development of smart biomaterials capable of adjusting ion release in response to environmental changes offers exciting possibilities for personalized regenerative therapies and this review provides a comprehensive understanding of how dynamic ion-releasing biomaterials actively shape the microenvironment to enhance healing, focusing on their ability to modulate biological processes such as osteogenesis and angiogenesis. By examining the latest advances in surface modifications and ion-release mechanisms, this review also aims to revise the potential of these materials to revolutionize regenerative medicine, offering knowledge to guide the development of next-generation biomaterials for improved clinical outcomes.

Non-Severe Hypophosphatemia in Older Patients: A Systematic Review

Background/Objectives: Phosphorus plays a fundamental role in cellular and extracellular metabolism, contributing to nucleic acid synthesis, enzymatic activity, neurologic function, and skeletal mineralization. Despite its significance, non-severe hypophosphatemia (HP) remains largely asymptomatic and underdiagnosed, with limited data on its prevalence in the general population. Most studies focus on specific subgroups, such as critically ill or dialysis patients, while the impact of mild HP in older adults, a potentially vulnerable demographic, is not well understood. The objective of this systematic review is to investigate the prevalence and clinical implications of non-severe HP in older adults. Methods: The study followed PRISMA guidelines to assess HP in patients aged ≥ 65 years without critical illnesses or genetic disorders. A systematic search was conducted in PubMed, Web of Science, and Scopus (March 2024). Eligible studies included RCTs and prospective/retrospective studies, excluding cancer-related studies or insufficient phosphate data. Results: We identified 1350 articles, with 26 meeting eligibility criteria. Ultimately, eight studies involving 26,548 patients were included, with an HP prevalence of 12.5%. Studies reveal a higher prevalence of HP in frail individuals, particularly those with increased frailty scores, and an association between HP and cognitive decline, depressed mood, falls, and chronic comorbidities. HP was also prevalent in infectious diseases, especially bacterial pneumonia, with longer hospital stays and increased mortality rates. Malnutrition was significantly more common in HP patients, characterized by weight loss and poor nutritional status. Furthermore, HP increased fall risk during hospitalization and worsened outcomes after coronary artery bypass graft surgery, including higher mortality and graft failure rates, underscoring its clinical importance. Discussion: This review identified that non-severe hypophosphatemia (HP) is associated with conditions such as frailty, cognitive decline, and an increased risk of falls. The evidence suggests that low phosphate levels may negatively impact health, increasing mortality and the risk of adverse clinical outcomes. Despite limitations in diagnostic criteria and sample variability, the findings indicate that HP can be a useful marker for identifying patients at risk of health deterioration. Further research is needed to clearly define the management and treatment of HP in this vulnerable population.

Elemental Profiling and Safety Assessment of Four Spice Vegetables: Insights into Nutritional and Toxicological Implications

Spiced vegetables are consumed globally, appreciated for their distinctive aromas and flavor profiles. Additionally, their unique elemental composition is recognized as a crucial parameter. This study aimed to evaluate the safety and toxicological risk of four commonly consumed spice vegetables: garlic (Allium sativum), ginger (Zingiber officinale), green onion (Allium fistulosum), and chili pepper (Capsicum annuum). Using ICP-OES and ICP-MS, a total of 25 elements, including macro, trace, and toxic elements, were determined. The analytical methods were validated per AOAC guidelines. Results indicated that potassium was the most abundant element across all samples, with garlic showing significantly higher concentrations of phosphorus, sulfur, and potassium. Trace element analysis revealed zinc and manganese as the most prevalent, with ginger exhibiting elevated levels of manganese, barium, and gallium. While toxic elements were detected in all samples, their concentrations remained within safe limits for human consumption. The estimated daily intake (EDI) and hazard quotient (HQ) analysis, based on Korean dietary data, confirmed minimal health risks. Heatmap analysis and linear discriminant analysis plots demonstrated the potential to distinguish between the four spice vegetables based on element profiles. This study highlights the importance of monitoring elemental compositions in spice vegetables to ensure food safety and reduce health risks from toxic elements, offering crucial insights into their nutritional value and safety.

Dairy consumption has a partial inverse association with systolic blood pressure and hypertension in populations with high salt and low dairy diets: cross-sectional data analysis from the Iwaki Health Promotion Project

The prevalence of hypertension in Japan remains high, owing to the high salt content of the typical Japanese diet. Dairy-based foods may reduce blood pressure and hypertension risk. However, dairy consumption is low in Japan, and the relationships between dairy intake and blood pressure or the mechanisms by which dairy products affect blood pressure are not fully understood. This cross-sectional study was conducted as part of the Iwaki Health Promotion Project in Aomori, Japan. A total of 1071 participants were included from those who underwent annual medical checkups in June 2015. Adjusted multivariate linear and logistic regression analyses were performed to analyze the relationships between dairy consumption and blood pressure or hypertension risk. Comprehensive blood biomarker measurements were also performed. Whole- and high-fat dairy consumption was found to have significant inverse associations with systolic blood pressure (SBP) for all participants (β = -0.0213, P = 0.044) and with SBP and systolic hypertension risk for non-users of antihypertensive medicines (β = -0.0306, P = 0.011; and OR = 0.9927, P = 0.016; respectively). Three blood biomarkers related to phosphorus metabolism (inorganic phosphorus, intact parathyroid hormone, and interleukin-6) were associated with both dairy consumption and SBP. Dairy consumption had a partial inverse association with SBP and hypertension risk in a Japanese population with high salt and low dairy consumption. Analysis of blood biomarkers suggested that phosphorus metabolism is involved in the associations between dairy consumption and blood pressure.

Effect of a single-dose denosumab on mineral homeostasis in infertile men: insights from a pilot intervention study and a randomized controlled trial

BACKGROUND

Denosumab, a drug that inhibits RANKL to reduce bone resorption in osteoporotic postmenopausal women, has been shown to improve semen quality in a subgroup of infertile men. This study aimed to investigate the effects of denosumab on mineral homeostasis in young infertile men.

METHODS

Secondary data from two clinical trials designed to test the effect on semen quality were used: (1) a pilot intervention study with 12 men receiving a single-dose of 60 mg denosumab and (2) a single-center, double-blinded, randomized clinical trial, where 100 infertile men were randomized 1:1 to receive denosumab 60 mg once sc. or placebo. A linear mixed model for repeated measures was employed to analyze data from follow-up samples.

RESULTS

In the pilot intervention study, denosumab treatment induced a decrease in ionized calcium 5, 20, 40, and 80 days after treatment compared with baseline (all p < 0.05). Serum phosphate decreased on all time points up to and including day 40 (all p < 0.05), while alkaline phosphatase was only lowered at 40 days and onwards (p = 0.014). Serum PTH increased significantly at all time points up to and including day 80 (p = 0.026). One hundred eighty days after treatment, all reported analyses were comparable to baseline levels. The observed temporal changes were confirmed in the RCT with differences in serum calcium (p < 0.001) and phosphate (p < 0.001) on day 14, PTH (p < 0.002), and alkaline phosphatase (p < 0.001) on days 80 and 160. Denosumab treatment had no significant effect on vitamin D status, renal function, or serum albumin concentration after 80 and 160 days.

CONCLUSIONS

Small but significant changes in mineral homeostasis and bone mineral content were observed but the changes were transient and normalized after treatment cessation. A single injection of denosumab in infertile men appears to have no major long-term impact on bone or mineral homeostasis.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03030196. Registered January 24, 2017.

Comparing the efficacy of serotonin and ethylene glycol tetraacetate on postpartum hypocalcemia

Inducing a transient state of hypocalcemia prepartum mobilizes stored Ca before the abrupt demand for Ca at parturition thus more tightly regulating postpartum hypocalcemia. Prepartum transient hypocalcemia can be achieved through intravenous infusions of either the precursor to serotonin, 5-hydroxy-tryptophan (5HTP) or a Ca chelating agent, ethylene glycol tetraacetic acid (EGTA). This study aimed to compare the ability of 5HTP and EGTA treatments to prevent postpartum hypocalcemia. We hypothesized that the 2 methods would be similarly effective compared with the control. Cows received either 5HTP, EGTA, 5HTP+EGTA, or control saline (n = 6/treatment) beginning 7 d before expected calving date through parturition (range 4-13 d). The 5HTP treatment was administered daily as a single 1-L dose at 1 mg/kg of BW. Saline and EGTA were infused for 6 h/d. Infusion rates of EGTA were adjusted to maintain blood ionized Ca (iCa) between 0.7 and 0.8 mM, inducing subclinical hypocalcemia, which occurs when iCa is 0.61-0.9 mM. Mammary biopsies were collected from rear quarters at 6, 30, 54, and 78 h postpartum. Cows in the 5HTP+EGTA group required less EGTA to maintain low iCa during infusions and had the lowest total Ca concentrations during infusions. Therefore, 5HTP and EGTA likely use different mechanisms to reduce blood Ca, which can occur simultaneously, resulting in an additive effect in blood Ca reduction. Control cows were subclinically hypocalcemic through 48 h postpartum, and 2 became clinically hypocalcemic. All other treatments were normocalcemic through 96 h postpartum and had significantly greater iCa than the control from 12 to 24 h postpartum. Administering 5HTP increased blood serotonin concentrations from the start of infusions through 72 h postpartum. Cows receiving EGTA or 5HTP+EGTA had decreased mammary Ca compared with the control at 54 and 78 h after calving. Mammary tissue quantitative PCR and Western blot analysis revealed increased gene and protein expression of Ca release-activated Ca modulator 1 on the day of parturition compared with 30 and 78 h postpartum. Mammary gland gene expression of the calcium-sensing receptor was decreased 78 h postpartum compared with 6 and 30 h postpartum. Although 5HTP and EGTA both prevented postpartum hypocalcemia, EGTA significantly increased iCa through 48 h post-calving rather than the 24 h in the 5HTP group. The 5HTP+EGTA and EGTA treatments were equally effective at regulating periparturient calcemic status, indicating that the additive effect of 5HTP and EGTA did not persist beyond parturition.

Physiological and biochemical responses of Labeo rohita to neonicotinoids imidacloprid, clothianidin, and their mixture

Neonicotinoids, widely used insecticides, pose severe environmental risks due to their persistence in soil and water, adversely affecting non-target organisms and ecosystem integrity. The present study examined the 56 days effects of imidacloprid (66.6 mg/l), clothianidin (30 mg/l), and their combination (33.3 mg/l and 15 mg/l) on Labeo rohita, using one-third of the LC50 sub-lethal concentrations. Survival, weight gain, and the hepatosomatic index decreased insignificantly in the IMI group and significantly in the CLO and Mix groups. Haematological indicators, including erythrocyte counts, haemoglobin, and haematocrit values, were also significantly reduced. Blood glucose and serum creatinine levels increased, while serum albumin, globulin, and plasma total proteins decreased. White blood cell counts elevated, while immunoglobulin (IgM), respiratory burst, and lysozyme activities were significantly inhibited. Liver, brain and muscle lactate and malate dehydrogenases were elevated, whereas succinate and glutamate dehydrogenases were decreased. Liver aspartate aminotransferase activity was substantially higher than that of brain and muscle, which had considerably higher levels of alanine aminotransferase in muscle than in the brain and liver. Additionally, muscle alkaline phosphatase activity was significantly higher than in the liver and brain, whereas liver acid phosphatase showed a greater elevation than in the muscle and brain. The physiological, haematological, and biochemical indices peaked on day 28 and slight recovery was observed on day 56 (IMI > CLO > Mix). The study highlights that the mixture of insecticides poses greater hazards compared to a single active compound, and the indiscriminate use of these insecticides jeopardizes non-target organisms, ecosystems, and public health.

Integrated transcriptomic analysis of human induced pluripotent stem cell-derived osteogenic differentiation reveals a regulatory role of KLF16

Osteogenic differentiation is essential for bone development, metabolism, and repair; however, the underlying regulatory relationships among genes remain poorly understood. To elucidate the transcriptomic changes and identify novel regulatory genes involved in osteogenic differentiation, we differentiated mesenchymal stem cells (MSCs) derived from 20 human iPSC lines into preosteoblasts (preOBs) and osteoblasts (OBs). We then performed transcriptome profiling of MSCs, preOBs and OBs. The iPSC-derived MSCs and OBs showed similar transcriptome profiles to those of primary human MSCs and OBs, respectively. Differential gene expression analysis revealed global changes in the transcriptomes from MSCs to preOBs, and then to OBs, including the differential expression of 840 genes encoding transcription factors (TFs). TF regulatory network analysis uncovered a network comprising 451 TFs, organized into five interactive modules. Multiscale embedded gene co-expression network analysis (MEGENA) identified gene co-expression modules and key network regulators (KNRs). From these analyses, KLF16 emerged as an important TF in osteogenic differentiation. We demonstrate that overexpression of Klf16 in vitro inhibited osteogenic differentiation and mineralization, while Klf16 +/- mice exhibited increased bone mineral density, trabecular number, and cortical bone area. Our study underscores the complexity of osteogenic differentiation and identifies novel regulatory genes such as KLF16, which plays an inhibitory role in osteogenic differentiation both in vitro and in vivo.

Structural basis of phosphate export by human XPR1

Phosphorus in crucial for all living organisms. In vertebrate, cellular phosphate homeostasis is partly controlled by XPR1, a poorly characterized inositol pyrophosphate-dependent phosphate exporter. Here, we report the cryo-EM structure of human XPR1, which forms a loose dimer with 10 transmembrane helices (TM) in each protomer. The structure consists of a scaffold domain (TM1, TM3-4) and a core domain (TM2, TM5-10) structurally related to ion-translocating rhodopsins. Bound phosphate is observed in a tunnel within the core domain at a narrow point that separates the tunnel into intracellular and extracellular vestibules. This site contains a cluster of basic residues that coordinate phosphate and a conserved W573 essential for export function. Loss of inositol pyrophosphate binding is accompanied by structural movements in TM9 and the W573 sidechain, closing the extracellular vestibule and blocking phosphate export. These findings provide insight into XPR1 mechanism and pave the way for further in-depth XPR1 studies.

[Etiology of hypophosphatemia in adults]

Long-term hypophosphatemia, defined by serum phosphorus (P) levels <2.5mg/dL, impairs the development and quality of mineralized tissue of the skeletal, dental, and auditory systems. P homeostasis depends mainly on intestinal absorption and renal excretion. Hypophosphatemia may be due to the redistribution of P to the intracellular space, increased renal losses, or decreased intestinal absorption. Hypophosphatemia can be categorized as acute or chronic, depending on the time course. Most cases, either acute or chronic, are due to acquired causes. However, some chronic cases may have a genetic origin. Accurate and early diagnosis, followed by adequate treatment, is essential to limit its negative effects on the body.

PER1 Oscillation in Rat Parathyroid Hormone and Calcitonin Producing Cells

Many endocrine glands exhibit circadian rhythmicity, but the interplay between the central circadian clock in the suprachiasmatic nucleus (SCN), the peripheral endocrine clock, and hormones is sparsely understood. We therefore studied the cellular localizations of the clock protein PER1, parathyroid hormone (PTH) and calcitonin (CT) in the parathyroid and thyroid glands, respectively. Thyroid glands, including the parathyroids, were dissected at different time-points from rats housed in 12 h:12 h light-darkness cycles, and were double-immunostained for PER1 and PTH or CT. Sera were analyzed for PTH, CT, phosphate, and calcium. In both glands, PER1 expression peaked late at night, while limited staining was seen during the daytime. High-resolution microscopy revealed cytosolic PER1 at zeitgeber time (ZT)12, and nucleic staining at ZT24 in both PTH and CT cells. PTH peaked at Z12-ZT16, while neither CT staining nor serum CT oscillated during the daily cycle. Serum PTH was significantly higher at ZT12 than ZT24, but only phosphate was found to exhibit significant diurnal oscillation. The staining of the calcium-sensitive receptor (CSR) did not demonstrate circadian oscillation. In conclusion, PER1 expression peaked late at night/early in the morning in hormone-producing cells of both the thyroid and parathyroid glands. In the parathyroids, this was preceded by a PTH peak, while neither CT nor CRS were found to oscillate.

Hypophosphataemia in Critical Illness: A Narrative Review

Phosphate is a predominately intracellular anion that has several key roles in normal cellular functions. Derangements in serum phosphate concentration occur frequently during critical illness, particularly hypophosphataemia, which has been reported in up to 75% of Intensive Care Unit (ICU) patients. The association between hypophosphataemia and ICU outcomes reported in the literature are conflicting and and subject to substantial confounding. Exogenous phosphate can be administered in the ICU using the enteral and intravenous route safely. However, whether administering phosphate and correcting hypophosphataemia results in any patient-centred benefits, or harms, remains uncertain, particularly for patients with mild hypophosphataemia or low-normal phosphate levels. This review will highlight key aspects of hypophosphataemia management in the critically ill, summarise current best practice, and outline major research priorities.

Sex-dependent interplay of phosphate and inflammation on muscle strength irrespective of muscle mass in middle-aged and older adults

BACKGROUND

Elevated circulatory phosphate levels are linked to age-related muscle dysfunction, yet the mechanisms remain unclear. This study investigated the hypothesis that inflammation plays a role in connecting elevated phosphate levels to muscular dysfunction in middle-aged and older individuals and explored potential sex-based differences in these associations.

METHODS

The study, based on the I-Lan Longitudinal Aging Study Cohort, analyzed individuals' serum phosphate and hsCRP levels. Sex-specific analyses explored links between circulatory phosphate, inflammation, and muscle profiles (mass, handgrip strength, and walking speed). The study also examined potential mediation or synergistic effects of inflammation in the circulatory phosphate-muscle relationship.

RESULTS

The study included 2006 participants (mean age: 65.5 ± 6.5 years; 49.8 % men). Women exhibited higher circulatory phosphate levels than men. Linear analyses revealed that higher phosphate levels were significantly associated with weaker handgrip strength but not with reduced muscle mass in both men and women. In women, circulatory phosphate was not associated with inflammation (hsCRP levels), while in men, higher phosphate levels were significantly associated with higher hsCRP levels. In men, a synergistic effect was observed, where the combination of high hsCRP and elevated phosphate levels had a more pronounced impact on reducing handgrip strength than either factor alone.

CONCLUSIONS

This study highlights a sex-specific association of inflammation in the mechanisms of hyperphosphatemia-related muscle weakness. The findings emphasize the importance of managing both hyperphosphatemia and chronic inflammation to mitigate their collective impact on muscle function, particularly in older men. Addressing these factors is crucial for promoting muscle health in later life.

Effects of inorganic phosphate on stem cells isolated from human exfoliated deciduous teeth

Calcium phosphate-based materials (CaP) are introduced as potential dental pulp capping materials for deciduous teeth. The present study investigated the influence of inorganic phosphate (Pi) on regulating stem cells isolated from human exfoliated deciduous teeth (SHED). SHEDs were treated with Pi. Cell cycle progression and apoptosis were examined using flow cytometry analysis. Osteo/odontogenic and adipogenic differentiation were analyzed using alizarin red S and oil red O staining, respectively. The mRNA expression profile was investigated using a high-throughput RNA sequencing technique. Pi increased the late apoptotic cell population while cell cycle progression was not altered. Pi upregulated osteo/odontoblastic gene expression and enhanced calcium deposition. Pi-induced mineralization was reversed by pretreatment of cells with Foscarnet, or p38 inhibitor. Pi treatment inhibited adipogenic differentiation as determined by decreased PPARγ expression and reduced intracellular lipid accumulation. Bioinformatic analysis of gene expression profiles demonstrated several involved pathways, including PI3K/AKT, MAPK, EGFR, and VEGF signaling. In conclusion, Pi enhanced osteo/odontogenic but inhibited adipogenic differentiation in SHED.

Influence of N- and/or P-restriction on bone metabolism in young goats

Ruminants can recycle nitrogen (N) and phosphorus (P), which are essential for vital body processes. Reduced N- and P-intake in ruminants is desirable for economic and ecologic reasons. Simultaneous modulation of mineral homoeostasis and bone metabolism occurs in young goats. This study aimed to investigate potential effects of dietary N- and/or P-restriction on molecular changes in bone metabolism. The twenty-eight young male goats were fed a control diet, an N-reduced diet, a P-reduced diet or a combined N- and P-reduced diet for 6-8 weeks. The N-restricted goats had lower plasma Ca concentration and higher plasma osteocalcin (OC) and CrossLaps concentrations. The P-restricted goats had reduced plasma inorganic phosphate (Pi) concentrations and increased plasma Ca concentrations. Due to the initiation of a signalling pathway that inhibits the fibroblast growth factor 23 (FGF23) expression, this was lower with P-restriction. Consequently, lower Pi concentrations were the main factor influencing the reduction in FGF23. The changes in mineral homoeostasis associated with P-restriction led to a reduction in OC, bone mineral content and mineral density. Simultaneously, bone resorption potentially increased with P-restriction as indicated by an increased receptor activator of NF-κB ligand/osteoprotegerin (OPG) ratio and an increase in OPG mRNA expression. Additionally, the increased mRNA expression of the calcitonin receptor during P-restriction points to a higher number of osteoclasts. This study demonstrates an impairment of bone remodelling processes in young goats by N- or P-restriction. With P-restriction, bone mineralisation rate was potentially reduced and bone quality impaired, while with N-restriction, bone remodelling increased.

Impact of Refeeding Syndrome on the Short-Term Clinical Outcomes of Very-Premature Infants

BACKGROUND

Refeeding syndrome (RFS) is a potentially life-threatening condition that can occur in preterm infants if nutritional support is initiated or increased after a period of starvation or malnutrition.

OBJECTIVES

The current study aimed to examine the short-term clinical outcomes of RFS in preterm infants born at ≤32 weeks of gestation.

METHODS

Infants with a gestational age of ≤32 weeks and a birth weight of <1500 g who were born and admitted to the level III neonatal intensive care unit and received parenteral nutrition upon admission were retrospectively evaluated. The modified log Poisson regression with generalized linear models and a robust variance estimator was applied to adjust the outcomes of infants.

RESULTS

In total, 760 infants met this study's inclusion criteria. Of them, 289 (38%) developed RFS. RFS was significantly associated with a composite outcome of mortality and intraventricular hemorrhage. Based on the multivariate Cox regression analysis adjusted for significant potential confounders, RFS was significantly associated with increased mortality risk, with a hazard ratio for death in infants with RFS being 1.74-fold higher compared to those without RFS.

CONCLUSIONS

Preterm infants born at ≤32 weeks of gestation who develop RFS within the first week of life are at increased risk for both intraventricular hemorrhage and mortality. This study underscores the need for standardized clinical approaches for managing RFS in the neonatal intensive care unit to improve outcomes. Future research should establish a unified RFS definition and conduct clinical trials to optimize parenteral nutrition strategies for this vulnerable population.

Styphnolobium japonicum Fruit and Germinated Soybean Embryo Complex Extract for Postmenopausal-Symptom Relief

BACKGROUND/OBJECTIVES

Hormonal alterations during menopause result in substantial physiological changes. Although hormone replacement therapy (HRT) is widely used as a treatment strategy for these changes, its use remains controversial due to its associated risks. Plant isoflavones are phytoestrogens that are considered a potential alternative therapy for postmenopausal syndrome. We aimed to investigate the efficacy of ethanolic extracts from Styphnolobium japonicum fruit (SJF) and germinated soybean embryo (GSE) in alleviating prominent menopausal symptoms.

METHODS

A cell model (MCF7 human breast cancer cells) was used to investigate estrogen-like activity. A rat ovariectomy model was used to simulate estrogen depletion after menopause and to evaluate the efficacy of the SJF-GSE complex extract at ratios of 1:1, 1:2, and 2:1.

RESULTS

Treatment with the SJF-GSE extract elicited estrogen-like effects, raising pS2 and estrogen receptor α expression in MCF7 cells. The extract was found to contain 48-72 mg/g sophoricoside and 8-12 mg/g soyasaponin 1, identified as active compounds. In ovariectomized rats, the extract effectively reduced body weight and fat content, alleviated vasomotor symptoms, improved vaginal mucosal health, and exerted osteoprotective effects by enhancing bone density and structure, reducing bone-resorption markers and positively altering estradiol levels and lipid profiles.

CONCLUSIONS

The SJF-GSE extract, working synergistically, provides a safe and effective alternative to HRT for managing postmenopausal symptoms and enhancing bone health, without adverse effects. These findings support the inclusion of SJF and GSE in health-functional foods and underscore the importance of further research into plant-based therapies for menopause.

Integrative cartilage repair using acellular allografts for engineered structure and surface lubrication in vivo

The repair of articular cartilage after damage is challenging, and decellularized tissue offers a possible treatment option to promote regeneration. Here, we show that acellular osteochondral allografts improve integrative cartilage repair compared to untreated defects after 6 months in an ovine model. Functional measures of intratissue strain/structure assessed by MRI demonstrate similar biomechanics of implants and native cartilage. Compared to native tissue and defects, the structure, composition, and tribology of acellular allografts preserve surface roughness and lubrication, material properties under compression and relaxation, compositional ratios of collagen:glycosaminoglycan and collagen:phosphate, and relative composition of types I/II collagen. While high cellularity was observed in bone regions and integration zones between cartilage-allografts, recellularization of chondral implants was inconsistent, with cell migration typically less than ~750 µm into the dense decellularized tissue, possibly limiting long-term cellular maintenance. Our results demonstrate the structural and biomechanical efficacy of acellular allografts for at least six months in vivo.

Human XPR1 structures reveal phosphate export mechanism

Inorganic phosphate (Pi) is a fundamental macronutrient for all living organisms, the homeostasis of which is critical for numerous biological activities1-3. As the only known human Pi exporter to date, XPR1 has an indispensable role in cellular Pi homeostasis4,5. Dysfunction of XPR1 is associated with neurodegenerative disease6-8. However, the mechanisms underpinning XPR1-mediated Pi efflux and regulation by the intracellular inositol polyphosphate (InsPP) sensor SPX domain remain poorly understood. Here we present cryo-electron microscopy structures of human XPR1 in Pi-bound closed, open and InsP6-bound forms, revealing the structural basis for XPR1 gating and regulation by InsPPs. XPR1 consists of an N-terminal SPX domain, a dimer-formation core domain and a Pi transport domain. Within the transport domain, three basic clusters are responsible for Pi binding and transport, and a conserved W573 acts as a molecular switch for gating. In addition, the SPX domain binds to InsP6 and facilitates Pi efflux by liberating the C-terminal loop that limits Pi entry. This study provides a conceptual framework for the mechanistic understanding of Pi homeostasis by XPR1 homologues in fungi, plants and animals.

Urinary Phosphate and Subclinical Atherosclerosis: The AWHS Study

(1) Background: Atherosclerosis is a leading cause of vascular death worldwide. High urinary phosphate has recently been identified as a cardiovascular risk factor, but its role has not been fully established. The aim of this study was to investigate the association between urinary phosphate and subclinical atherosclerosis in the carotid, femoral as well as coronary territories; (2) Methods: We performed a cross-sectional analysis of a sample of 1169 middle-aged men, aged 50.9 years (SD 3.7), without previous cardiovascular disease, belonging to the Aragon Workers Health Study (AWHS). Urinary phosphate was analyzed in urine samples using the Fiske-Subbarow method. The presence of carotid plaque and femoral plaque was assessed by ultrasound and coronary artery calcium score (CACS) by computed tomography. Demographic, anthropometric and clinical data were collected at annual medical examinations. Logistic regression models were used to estimate the prevalence of adjusted atherosclerosis in the different vascular arteries; (3) Results: A significant inverse association was observed between urinary phosphate and subclinical atherosclerosis in the carotid [OR 95% CI 0.69 (0.49-0.99)] and coronary (CACS > 200) [OR 95% CI 0.46 (0.23-0.88)] arteries; however, no statistically significant association was found between urinary phosphate and the presence of atheroma plaques in the femoral territory [OR 1.02 (0.72-1.45)]; (4) Conclusions: In middle-aged men, a higher urinary phosphate concentration is associated with a lower prevalence of subclinical carotid and coronary atherosclerosis compared with those with a lower urinary phosphate concentration.

The Impact of Prescription Time Limits on Phosphate Administration in the Intensive Care Unit: A Before-After Quality Improvement Study

(1) Background: We aim to examine and improve phosphate prescribing as part of a quality assurance program by examining the change in the proportion of patients receiving phosphate with normal or high preceding serum phosphate concentrations before and after the introduction of the 24 h time limit to default phosphate prescription. (2) Methods: This was a quality assurance study conducted across three Australian adult intensive care units (ICUs). All adult patients with ICU lengths of stay greater than or equal to 48 h who had their serum phosphate concentrations measured were included. A 24 h time limit was introduced to the protocolised prescription in the electronic clinical information system for enteral and intravenous phosphate at participating ICUs. Patient characteristics, phosphate administration, and outcomes were compared before and after this time limit was introduced. The primary outcome was the proportion of patients to whom phosphate was prescribed after measurement of a normal or high serum phosphate level. Secondary outcomes were ICU length of stay, mortality, and discharge destination. (3) Results: A total of 1192 patients were included from three ICUs over the two periods. The proportion of patients with a normal or high measured phosphate level who then received phosphate supplementation was significantly lower in the second study period (30.3% vs. 9.9%; p < 0.001). This difference persisted when adjusted for potential confounders in a mixed-effects logistic regression model (an adjusted odds ratio for receiving phosphate with normal or high serum concentration 0.214, 95% confidence interval of 0.132-0.347; p < 0.001). No significant difference was seen in the typical ICU length of stay, in-hospital case-fatality rate, and hospital discharge destination between these groups. (4) Conclusions: This multicentre before-after study has demonstrated that the introduction of a 24 h limit on electronic phosphate prescriptions resulted in significantly fewer patients receiving phosphate when their serum phosphate concentration was normal or high, without any adverse impact on patient outcomes.

A bi-functional nanofibrous composite membrane for wound healing applications

Various wound dressings have been developed so far for wound healing, but most of them are ineffective in properly reestablishing the skin's structure, which increases infection risks and dehydration. Electrospun membranes are particularly interesting for wound dressing applications because they mimic the extracellular matrix of healthy skin. In this study, a potential wound healing platform capable of inducing synergistic antibacterial and antioxidation activities was developed by incorporating bio-active rosmarinic acid-hydroxyapatite hybrid (HAP-RA) with different contents (0.5, 1, and 1.5 wt.%) into the electrospun polyamide 6 (PA6) nanofibers. Then, polyethylene glycol (PEG) was introduced to the nanofibrous composite to improve the biocompatibility and biodegradability of the dressing. The results indicated that the hydrophilicity, water uptake, biodegradability, and mechanical properties of the obtained PA6/PEG/HAP-RA nanofibrous composite enhanced at 1 wt.% of HAP-RA. The nanofibrous composite had excellent antibacterial activity. The antioxidation potential of the samples was assessed in vitro. The MTT assay performed on the L929 cell line confirmed the positive effects of the nanofibrous scaffold on cell viability and proliferation. According to the results, the PA6/PEG/HAP-RA nanofibrous composite showed the desirable physiochemical and biological properties besides antibacterial and antioxidative capabilities, making it a promising candidate for further studies in wound healing applications.

Secondary hyperparathyroidism in chronic kidney disease: pathophysiology, current treatments and investigational drugs

INTRODUCTION

Secondary hyperparathyroidism (SHPT) is a common complication of chronic kidney disease (CKD). It begins as an adaptive increase in parathyroid hormone levels to prevent calcium and phosphate derangements. Over time, this condition becomes maladaptive and is associated with increased morbidity and mortality. Current therapies encompass phosphate-lowering strategies, vitamin D analogues, calcimimetics and parathyroidectomy. These approaches harbor inherent limitations, stimulating interest in the development of new drugs for SHPT to overcome these limitations and improve survival and quality of life among CKD patients.

AREAS COVERED

This review delves into the main pathophysiological mechanisms involved in SHPT, alongside the treatment options that are currently available and under active investigation. Data presented herein stem from a comprehensive search conducted across PubMed, Web of Science, ClinicalTrials.gov and International Clinical Trials Registry Platform (ICTRP) spanning from 2000 onwards.

EXPERT OPINION

The advancements in investigational drugs for SHPT hold significant promise for enhancing treatment efficacy while minimizing side effects associated with conventional therapies. Although several challenges still hinder their adoption in clinical practice, ongoing research will likely continue to expand the available therapeutic options, refine treatment strategies, and tailor them to individual patient profiles.

Hypophosphatemia attenuates improvements in vitality after intravenous iron treatment in patients with inflammatory bowel disease

PURPOSE

Iron deficiency anemia is common in people with inflammatory bowel disease (IBD), causing deterioration in quality of life, which can be reversed by treatment that increases iron stores and hemoglobin levels. The present post hoc analyses estimate health state utility values for patients with IBD after treatment with ferric derisomaltose or ferric carboxymaltose and evaluate the health domains driving the changes.

METHODS

SF-36v2 responses were recorded at baseline and day 14, 35, 49, and 70 from 97 patients enrolled in the randomized, double-blind, PHOSPHARE-IBD trial (ClinicalTrials.gov ID: NCT03466983), in which patients with IBD across five European countries were randomly allocated to either ferric derisomaltose or ferric carboxymaltose. Changes in SF-36v2 scale scores and SF-6Dv2 health utility values were analyzed by mixed models.

RESULTS

In both treatment arms, SF-6Dv2 utility values and all SF-36v2 scale scores, except Bodily Pain, improved significantly (p =  < 0.0001). The improvement in SF-6Dv2 utility values showed no significant treatment group difference. The improvement in utility values was completely explained by improvement in Vitality scores. Vitality scores showed significantly larger improvement with ferric derisomaltose versus ferric carboxymaltose (p = 0.026). Patients with the smallest decrease in phosphate had significantly larger improvements in Vitality scores at each time point (p =  < 0.05 for all comparisons) and overall (p = 0.0006).

CONCLUSIONS

Utility values improved significantly with intravenous iron treatment. Improvement in utility values was primarily driven by Vitality scores, which showed significantly greater improvement in the ferric derisomaltose arm. Smaller decreases in phosphate were associated with significantly higher Vitality scores, suggesting that quality of life improvement is attenuated by hypophosphatemia. The utility values can inform future cost-utility analysis.

Nutrient and Hormonal Effects on Long Bone Growth in Healthy and Obese Children: A Literature Review

Longitudinal bone growth is mediated through several mechanisms including macro- and micronutrients, and endocrine and paracrine hormones. These mechanisms can be affected by childhood obesity as excess adiposity may affect signaling pathways, place undue stress on the body, and affect normal physiology. This review describes the physiology of the epiphyseal growth plate, its regulation under healthy weight and obesity parameters, and bone pathology following obesity. A literature review was performed utilizing PubMed, PMC, NIH, and the Cochrane Database of Systematic Reviews pertinent to hormonal and nutritional effects on bone development, child obesity, and pathologic bone development related to weight. The review indicates a complex network of nutrients, hormones, and multi-system interactions mediates long bone growth. As growth of long bones occurs during childhood and the pubertal growth spurt, pediatric bones require adequate levels of minerals, vitamins, amino acids, and a base caloric supply for energy. Recommendations should focus on a nutrient-dense dietary approach rather than restrictive caloric diets to maintain optimal health. In conclusion, childhood obesity has profound multifaceted effects on the developing musculoskeletal system, ultimately causing poor nutritional status during development. Weight loss, under medical supervision, with proper nutritional guidelines, can help counteract the ill effects of childhood obesity.

Ferric carboxymaltose-induced hypophosphatemia - a case series

Hypophosphatemia may cause serious complications. Depending on its severity and duration, signs and symptoms range from fatigue to life-threatening events, like severe rhabdomyolysis and mental status changes. Long-term consequences include osteomalacia. Hypophosphatemia may be secondary to the use of parental iron, mostly associated with ferric carboxymaltose (FCM), with an incidence of around 45% to 70%. We describe three cases of hypophosphatemia in patients with chronic iron deficiency anemia, requiring repeated FCM infusions. The patients' presentation to the Rheumatology department included musculoskeletal symptoms of severe hypophosphatemia and long-term hypophosphatemic osteomalacia, with fractures. We aim to raise awareness for ferric carboxymaltose-induced hypophosphatemia, an entity increasingly described in the literature that can be responsible for severe disability or potentially life-threatening adverse events.

Phosphorus balance calculator: an individualized tool for treatment of hyperphosphatemia in hemodialysis patients

BACKGROUND

Lack of evaluations of the dietary phosphorus and dialysis phosphorus removal in daily clinical practice are common obstacles to assessing phosphorus balance and controlling phosphorus in hemodialysis patients. We aimed to investigate whether individualized therapy using a phosphorus balance calculator improves phosphorus control.

METHODS

A randomized, open-label, multicenter, 4-week clinical trial was conducted. A total of 119 maintenance hemodialysis patients aged 18-85 years old and with serum phosphorus level >1.45 mmol/L from three university teaching hospitals in Shanghai were enrolled. Patients were randomized in a 1:1 ratio to individualized therapy (n = 60) or conventional therapy (n = 59). The primary outcome was the serum phosphorus concentration after 4-week treatment. Secondary outcomes included the serum calcium and parathyroid hormone (PTH) concentrations, changes in serum phosphorus, calcium and PTH concentrations, and the proportion of patients achieving target ranges of serum phosphorus, calcium and PTH after 4-week treatment.

RESULTS

Among 119 randomized participants [mean age 62 years; 68 male (57%)], 116 completed the trial. Using the phosphorus balance calculator, the individualized group achieved a better phosphorus balance state and significantly reduced serum phosphorus (1.62 ± 0.45 mmol/L versus 1.85 ± 0.45 mmol/L, P = .006), increased the proportions of patients achieving target serum phosphorus range (41% versus 18%, P = .006) and had greater adjusted mean difference in change in serum phosphorus over the 4 weeks (-0.47 versus -0.23 mmol/L, P = .010) when compared with conventional therapy. No significant changes were observed in serum calcium and PTH levels, the proportion of patients achieving target serum calcium or PTH levels, or the adjusted mean difference of serum calcium and PTH levels over the treatment period.

CONCLUSION

Phosphorus balance calculator was proved to improve serum phosphorus control in patients undergoing maintenance hemodialysis, offering a new tool for managing hyperphosphatemia.

Phosphorus Knowledge and Dietary Intake of Phosphorus of US Adults Undergoing Dialysis

Abnormal serum phosphorus is a concern for adults undergoing dialysis due to the risk for mortality and morbidity. General recommendations for maintaining serum phosphorus within normal limits is monitoring dietary intake of phosphorus and taking phosphate binders, as prescribed. However, limited research is available about adults' phosphorus knowledge and dietary intake of phosphorus. The purpose of this cross-sectional study was to determine the association between phosphorus knowledge and dietary intake of phosphorus of adults on dialysis. An online Qualtrics survey was conducted during February-September 2023. Participants (n = 107) responded to the 74-item questionnaire (30-day food frequency questionnaire, phosphorus knowledge questionnaire, and demographic questions). Analysis included frequencies, descriptive statistics, t-tests, and Spearman correlations. JMP SAS v16 was used with a statistical significance of p < 0.05. Of the participants, 57.0% (n = 61) were on peritoneal dialysis and 43.0% (n = 46) were on hemodialysis. Average phosphorus knowledge score was 10.6 ± 3.0 out of 19 or 55.8%, with those on peritoneal dialysis having lower scores (54.7%) compared to participants on hemodialysis (58.1%) (p < 0.05). The daily average dietary phosphorus intake was 605 ± 297 mg. Participants on peritoneal dialysis consumed more phosphorus (625 mg) compared to participants on hemodialysis (576 mg) (p < 0.05). There was no association with phosphorus knowledge scores and dietary intake of phosphorus. There were positive correlations between discussing about phosphorus, knowing serum phosphorus concentration, and phosphorus knowledge scores. These results can aid practitioners in providing tailored nutrition education among adults on dialysis.

Tubular phosphate transport: a comparison between different methods of urine sample collection in FGF23-dependent hypophosphatemic syndromes

OBJECTIVES

Tubular maximum phosphate reabsorption per glomerular filtration rate (TmP/GFR) is used to evaluate renal phosphate reabsorption and it is a useful tool for the differential diagnosis of hypophosphatemic syndromes. TmP/GFR is typically calculated from fasting plasma and second morning void urine samples, obtained 2 h after the first void (TmP/GFR 2 h). The purpose of this study was to evaluate if TmP/GFR calculated from 24 h urine collection (TmP/GFR 24 h) can be used as an alternative for TmP/GFR 2 h in patients with urine phosphate wasting.

METHODS

We enrolled adult patients with X-linked hypophosphatemia (XLH) or tumor-induced osteomalacia (TIO). All patients underwent blood and urine sample collections, to calculate TmP/GFR 24 h and TmP/GFR 2 h.

RESULTS

Twenty patients (17 XLH and 3 TIO), aged 24-78 years, were included. All patients had low TmP/GFR 2 h (0.35 mmol/L, IQR 0.24-0.47 mmol/L) and TmP/GFR 24 h (0.31 mmol/L, IQR 0.22-0.43 mmol/L). The concordance correlation coefficient between TmP/GFR 2 h and TmP/GFR 24 h was 0.86 (95 % CI: 0.69-0.93), with a systematic bias of 0.05 mmol/L (95 % limits of agreement: -0.10 to 0.20). Furthermore, in 70 % (i.e., 14 patients out of 20) and 80 % (i.e., 16 patients out of 20) of cases the difference between TmP/GFR 2 h and TmP/GFR 24 h was within ±30 % and ±35 %, respectively.

CONCLUSIONS

Despite TmP/GFR 2 and 24 h show a relatively suboptimal agreement, the difference between the two parameters appears to be small and not clinically significant in the setting of adult patients with FGF23-dependent urine phosphate wasting and secondary hypophosphatemia.

The molecular sociology of NHERF1 PDZ proteins controlling renal hormone-regulated phosphate transport

Parathyroid hormone (PTH) and fibroblast growth factor-23 (FGF23) control extracellular phosphate levels by regulating renal NPT2A-mediated phosphate transport by a process requiring the PDZ scaffold protein NHERF1. NHERF1 possesses two PDZ domains, PDZ1 and PDZ2, with identical core-binding GYGF motifs explicitly recognizing distinct binding partners that play different and specific roles in hormone-regulated phosphate transport. The interaction of PDZ1 and the carboxy-terminal PDZ-binding motif of NPT2A (C-TRL) is required for basal phosphate transport. PDZ2 is a regulatory domain that scaffolds multiple biological targets, including kinases and phosphatases involved in FGF23 and PTH signaling. FGF23 and PTH trigger disassembly of the NHERF1-NPT2A complex through reversible hormone-stimulated phosphorylation with ensuing NPT2A sequestration, down-regulation, and cessation of phosphate absorption. In the absence of NHERF1-NPT2A interaction, inhibition of FGF23 or PTH signaling results in disordered phosphate homeostasis and phosphate wasting. Additional studies are crucial to elucidate how NHERF1 spatiotemporally coordinates cellular partners to regulate extracellular phosphate levels.

Effect of early serum phosphate disorder on in-hospital and 28-day mortality in sepsis patients: a retrospective study based on MIMIC-IV database

BACKGROUND

This study aims to assess the influence of early serum phosphate fluctuation on the short-term prognosis of sepsis patients.

METHODS

This retrospective study used the Medical Information Mart for Intensive Care IV database to analyze serum phosphate levels in sepsis patients within 3 days of ICU admission. According to the absolute value of delta serum phosphate (the maximum value minus the minimum value of serum phosphorus measured within three days), the patients were divided into four groups, 0-1.3, 1.4-2.0, 2.1-3.1, and ≥ 3.2 mg/dl. Meanwhile, the direction of delta serum phosphate was compared. With the serum phosphate change group of 0-1.3 mg/dl as the reference group, the relationship between delta serum phosphate and in-hospital mortality and 28-day mortality was analyzed by multivariate Logistics regression analysis.

RESULTS

The study involved 1375 sepsis patients. Serum phosphate changes (0-1.3, 1.4-2.0, 2.1-3.1, and ≥ 3.2 mg/dl) correlated with in-hospital and 28-day mortality variations (p = 0.005, p = 0.008). Much higher serum phosphate fluctuation elevated in-hospital and 28-day mortality. Compared to the 0-1.3 mg/dl change group, adjusted odds ratios (OR) in other groups for in-hospital mortality were 1.25 (0.86-1.81), 1.28 (0.88-1.86), and 1.63 (1.10-2.43), and for 28-day mortality were 1.21 (0.86-1.72), 1.10 (0.77-1.57), and 1.49 (1.03-2.19). Under the trend of increasing serum phosphate, the ORs of in-hospital mortality and 28-day mortality in ≥ 3.2 mg/dl group were 2.52 and 2.01, respectively.

CONCLUSION

In conclude, the delta serum phosphate ≥ 3.2 mg/dl was associated with in-hospital mortality and 28-day mortality in patients with sepsis.

Inclusion of guanidinoacetic acid in a low metabolizable energy diet improves broilers growth performance by elevating energy utilization efficiency through modulation serum metabolite profile

This study was aimed to explore the elevating energy utilization efficiency mechanism for the potentially ameliorative effect of guanidinoacetic acid (GAA) addition on growth performance of broilers fed a low metabolizable energy (LME) diet. A total of 576 d old broilers were randomly allocated to one of the six treatments: a basal diet (normal ME, positive control, PC), or an LME diet (50 kcal/kg reduction in ME, negative control, NC) supplemented with 0.02%, 0.04%, 0.06%, and 0.08% GAA from 1 to 42 d of age, respectively. The GAA fortification in LME diet linearly or quadratically dropped (P < 0.05) the feed conversion ratio (FCR) from 22 to 42 and 1 to 42 d of age, abdominal fat rate on day 42, serum alanine aminotransferase (ALT) on day 21, and serum creatinine (CREAN) on days 21 and 42, elevated (P < 0.05) breast muscle rate and leg muscle rate on day 42, serum creatine kinase (CK) on days 21 and 42, as well as alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) on day 21. The dietary optimal GAA levels were 0.03%-0.08% based on the best-fitted quadratic models (P < 0.03) of the above parameters. Thus, the PC, LME, and 0.04% GAA-LME groups were selected for further analysis. Serum essential amino acids (EAA) tryptophan, histidine and arginine, non-essential amino acids (NEEA) serine, glutamine and aspartic acid were significantly decreased (P < 0.05), compared to PC diet by LME or 0.04% GAA-LME diet. 0.04% GAA-LME group reversed (P < 0.05) the reduction of arginine, 3-methyhistidine, and 1-methylhistidine by LME diet. Besides, six birds at 28 d of age from LME and 0.04% GAA-LME groups were selected for energy utilization observation in calorimetry chambers. The results demonstrated that 0.04% GAA-LME group significantly improved (P < 0.05) the ME intake (MEI) and net energy (NE) compared to the LME diet. Overall, these findings suggest that 0.04% GAA is the ideal dose of broilers fed the LME diet, which can significantly improve the growth performance and carcass characteristics by modulation of creatine metabolism through elevating serum CK activity and arginine concentration.

CO2-based production of phytase from highly stable expression plasmids in Cupriavidus necator H16

BACKGROUND

Existing plasmid systems offer a fundamental foundation for gene expression in Cupriavidus necator; however, their applicability is constrained by the limitations of conjugation. Low segregational stabilities and plasmid copy numbers, particularly in the absence of selection pressure, pose challenges. Phytases, recognized for their widespread application as supplements in animal feed to enhance phosphate availability, present an intriguing prospect for heterologous production in C. necator. The establishment of stable, high-copy number plasmid that can be electroporated would support the utilization of C. necator for the production of single-cell protein from CO2.

RESULTS

In this study, we introduce a novel class of expression plasmids specifically designed for electroporation. These plasmids contain partitioning systems to boost segregation stability, eliminating the need for selection pressure. As a proof of concept, we successfully produced Escherichia coli derived AppA phytase in C. necator H16 PHB- 4 using these improved plasmids. Expression was directed by seven distinct promoters, encompassing the constitutive j5 promoter, hydrogenase promoters, and those governing the Calvin-Benson-Bassham cycle. The phytase activities observed in recombinant C. necator H16 strains ranged from 2 to 50 U/mg of total protein, contingent upon the choice of promoter and the mode of cell cultivation - heterotrophic or autotrophic. Further, an upscaling experiment conducted in a 1 l fed-batch gas fermentation system resulted in the attainment of the theoretical biomass. Phytase activity reached levels of up to 22 U/ml.

CONCLUSION

The new expression system presented in this study offers a highly efficient platform for protein production and a wide array of synthetic biology applications. It incorporates robust promoters that exhibit either constitutive activity or can be selectively activated when cells transition from heterotrophic to autotrophic growth. This versatility makes it a powerful tool for tailored gene expression. Moreover, the potential to generate active phytases within C. necator H16 holds promising implications for the valorization of CO2 in the feed industry.

A comprehensive review on nanocomposite biomaterials based on gelatin for bone tissue engineering

The creation of a suitable scaffold is a crucial step in the process of bone tissue engineering (BTE). The scaffold, acting as an artificial extracellular matrix, plays a significant role in determining the fate of cells by affecting their proliferation and differentiation in BTE. Therefore, careful consideration should be given to the fabrication approach and materials used for scaffold preparation. Natural polypeptides such as gelatin and collagen have been widely used for this purpose. The unique properties of nanoparticles, which vary depending on their size, charge, and physicochemical properties, have demonstrated potential in solving various challenges encountered in BTE. Therefore, nanocomposite biomaterials consisting of polymers and nanoparticles have been extensively used for BTE. Gelatin has also been utilized in combination with other nanomaterials to apply for this purpose. Composites of gelatin with various types of nanoparticles are particularly promising for creating scaffolds with superior biological and physicochemical properties. This review explores the use of nanocomposite biomaterials based on gelatin and various types of nanoparticles together for applications in bone tissue engineering.

Phosphate Homeostasis and Disorders of Phosphate Metabolism

Phosphate is indispensable for human life and evolutionary changes over several millions of years have established tightly regulated mechanisms to ensure phosphate homeostasis. In this process, calcium and phosphate metabolism have come to be intricately linked together. Three hormones (PTH, FGF23 and Calcitriol) maintain the fine balance of calcium and phosphate metabolism through their actions at three sites (the gut, the kidneys and the skeleton). Disorders that disrupt this balance can have serious clinical consequences. Acute changes in serum phosphate levels can result in life threatening complications like respiratory failure and cardiac arrythmias. Chronic hypophosphataemia predominantly affects the musculoskeletal system and presents as impaired linear growth, rickets, osteomalacia and dental problems. Hyperphosphataemia is very common in the setting of chronic kidney disease and can be difficult to manage. A thorough understanding of calcium and phosphate homeostasis is essential to diagnose and treat conditions associated with hypo and hyperphosphataemia. In this review, we will discuss the calcium and phosphate metabolism, aetiologies and management of hypo and hyperphosphataemia.

Phosphate Prodrugs: An Approach to Improve the Bioavailability of Clinically Approved Drugs

The phosphate prodrug approach has emerged as a viable option for increasing the bioavailability of a drug candidate with low hydrophilicity and poor cell membrane permeability. When a phosphoric acid moiety is attached to the parent drug, it results in a several-fold elevation in aqueous solubility which helps to achieve desired bioavailability of the pharmaceutically active parental molecule. The neutral phosphate prodrugs have rapid diffusion ability through the plasma membrane as compared to their charged counterpart. The presence of phosphate mono ester breaking alkaline phosphatase (ALP) enzyme throughout the whole human body, is the main consideration behind the development of phosphate prodrug strategy. The popularity of this phosphate prodrug strategy is increasing nowadays due to the fulfillment of different desired pharmacokinetic characteristics required to get pharmaceutical and therapeutic responses without showing any serious adverse drug reactions (ADR). This review article mainly focuses on various phosphate prodrugs synthesized within the last decade to get an improved pharmacological response of the parent moiety along with various preclinical and clinical challenges associated with this approach. Emphasis is also given to the chemical mechanism to release the parent moiety from the prodrug.

Bioactive elements manipulate bone regeneration

While bone tissue is known for its inherent regenerative abilities, various pathological conditions and trauma can disrupt its meticulously regulated processes of bone formation and resorption. Bone tissue engineering aims to replicate the extracellular matrix of bone tissue as well as the sophisticated biochemical mechanisms crucial for effective regeneration. Traditionally, the field has relied on external agents like growth factors and pharmaceuticals to modulate these processes. Although efficacious in certain scenarios, this strategy is compromised by limitations such as safety issues and the transient nature of the compound release and half-life. Conversely, bioactive elements such as zinc (Zn), magnesium (Mg) and silicon (Si), have garnered increasing interest for their therapeutic benefits, superior stability, and reduced biotic risks. Moreover, these elements are often incorporated into biomaterials that function as multifaceted bioactive components, facilitating bone regeneration via release on-demand. By elucidating the mechanistic roles and therapeutic efficacy of the bioactive elements, this review aims to establish bioactive elements as a robust and clinically viable strategy for advanced bone regeneration.

Phosphorus - a scoping review for Nordic Nutrition Recommendations 2023

This scoping review aims to describe the totality of evidence for the role of phosphorus for health-related outcomes as a basis for setting and updating dietary reference values (DRVs). Phosphorus is needed in many biological processes, such as cellular metabolism and bone mineralization. Dietary phosphorus intake exceeds the previous Nordic Nutrition Recommendations (NNR2012) 2-3-fold in the Nordic countries. Intake from food additives is unknown but may play a significant role because the use of phosphate additives is common in the food industry. Bioavailability of phosphorus in plant-based products is lower than animal-based products. Nevertheless, bioavailability of phosphorus additives is higher. The main phosphorus-related health outcomes concern high phosphorus intake mainly from food additives with potential adverse effects on kidney, bone, and cardiovascular health.

Fe(III) cross-linked cellulose-agar hydrogel beads for efficient phosphate removal from aqueous solutions

Fe(III) cross-linked cellulose agar beads (Fe-CLCAB) were synthesized by sol-gel method and employed as adsorbents for the removal of phosphate ions from aqueous medium. The synthesized Fe-CLCAB was characterized by its swelling property, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and UV-Vis absorption spectroscopic analysis. Batch adsorption studies were carried out to find out the optimum conditions of phosphate uptake. The adsorption process was found to fit both Langmuir and Freundlich adsorption isotherm model, pseudo-second-order kinetic model, and Elovich kinetic model. Ninety-four percent phosphate adsorption was achieved with 500 beads at pH 5. Maximum monolayer adsorption capacity was 73.13 mg/g. A two-step elution process using sodium chloride solution was suitable for complete desorption of phosphate from Fe-CLCAB. Six cyclic adsorption-desorption tests were conducted using a 0.1 M NaCl solution as desorbing agent. The removal efficiency of regenerated Fe-CLCAB was 42% of its original value after six cycles, which validates good stability and effectiveness of the prepared hydrogel beads. Ion exchange plays a vital role during adsorption/desorption of phosphate.

A Novel Heterozygous Mutation c.1627G>T (p.Gly543Cys) in the SLC34A1 Gene in a Male Patient with Recurrent Nephrolithiasis and Early Onset Osteopenia: A Case Report

Serum phosphate concentration is regulated by renal phosphate reabsorption and mediated by sodium-phosphate cotransporters. Germline mutations in genes encoding these cotransporters have been associated with clinical phenotypes, variably characterized by hyperphosphaturia, hypophosphatemia, recurrent kidney stones, skeletal demineralization, and early onset osteoporosis. We reported a 33-year-old male patient presenting a history of recurrent nephrolithiasis and early onset osteopenia in the lumbar spine and femur. He was tested, through next generation sequencing (NGS), by using a customized multigenic panel containing 33 genes, whose mutations are known to be responsible for the development of congenital parathyroid diseases. Two further genes, SLC34A1 and SLC34A3, encoding two sodium-phosphate cotransporters, were additionally tested. A novel germline heterozygous mutation was identified in the SLC34A1 gene, c.1627G>T (p.Gly543Cys), currently not reported in databases of human gene mutations and scientific literature. SLC34A1 germline heterozygous mutations have been associated with the autosomal dominant hypophosphatemic nephrolithiasis/osteoporosis type 1 (NPHLOP1). Consistently, alongside the clinical features of NPHLOP1, our patient experienced recurrent nephrolithiasis and lumbar and femoral osteopenia at a young age. Genetic screening for the p.Gly453Cys variant and the clinical characterization of his first-degree relatives associated the presence of the variant in one younger brother, presenting renal colic and microlithiasis, suggesting p.Gly453Cys is possibly associated with renal altered function in the NPHLOP1 phenotype.

An in vitro model system based on calcium- and phosphate ion-induced hMSC spheroid mineralization

A challenge in regenerative medicine is creating the three-dimensional organic and inorganic in vitro microenvironment of bone, which would allow the study of musculoskeletal disorders and the generation of building blocks for bone regeneration. This study presents a microwell-based platform for creating spheroids of human mesenchymal stromal cells, which are then mineralized using ionic calcium and phosphate supplementation. The resulting mineralized spheroids promote an osteogenic gene expression profile through the influence of the spheroids' biophysical environment and inorganic signaling and require less calcium or phosphate to achieve mineralization compared to a monolayer culture. We found that mineralized spheroids represent an in vitro model for studying small molecule perturbations and extracellular mediated calcification. Furthermore, we demonstrate that understanding pathway signaling elicited by the spheroid environment allows mimicking these pathways in traditional monolayer culture, enabling similar rapid mineralization events. In sum, this study demonstrates the rapid generation and employment of a mineralized cell model system for regenerative medicine applications.

The impact of vitamin D on clinical parameters and bone turnover biomarkers in ligature-induced periodontitis: An experimental study in rats

Objectives and Background

Vitamin D has been associated with an increased risk of tooth loss and the severity of periodontal diseases. This study aimed to evaluate the effect of vitamin D on the clinical, radiographic, and serum level changes of bone turnover biomarkers in ligature-induced periodontitis.

Methods

A total of 28 rats were included in this study and divided into test groups: Vitamin D supplement (VS), Vitamin D deficient (VD), and control (CG). Ligature-induced periodontal tissue destruction was performed and kept for 21 days. Clinical attachment and radiographic changes were recorded, and serum samples were tested for Osteoprotegerin (OPG), Dickkopf-1 (DKK1), Sclerostin (SOST), and Fibroblast growth factor 23 (FGF23) on the initial and final day of the study.

Results

Groups that were made VD exhibited a more significant amount of clinical attachment loss (1.05 ± 0.50 mm) compared to the CG (0.83 ± 0.14 mm) and VS group (0.60 ± 0.13 mm), showing significant differences (p < 0.05). The radiographic alveolar bone loss amount was greater in the VD group compared to the other groups. For serum level assessment, the VD groups also exhibited a statistically significant reduction in the levels of OPG. They showed higher concentrations of DKK1, SOST, and FGF23 than other groups, with significant differences (p < 0.05).

Conclusion

The results revealed that Vitamin D may play a role in the progression of periodontal disease. It was found to affect both clinical parameters and bone turnover biomarkers, suggesting its potential impact on the disease process.