Glycolate oxidase-1 gene variants influence the risk of hyperoxaluria and renal stone development

PURPOSE

Oxalate is an excellent calcium ion attractor with great abundance in the human body, and the liver is the major source of oxalate. The Glycolate oxidase-1 (GOX1) gene is solely responsible for the glycolate and glyoxylate metabolism and produces oxalate. This study has been designed to comprehend the association of genetic variants of the GOX1 gene with the risk of hyperoxaluria and renal stone disease in the Indian population.

METHOD

The present study is a candidate gene approach prospective case-control study carried out on 300 participants (150 cases and 150 controls) at Muljibhai Patel Urological Hospital, Gujarat, India. Biochemical parameters, including serum levels of calcium, creatinine, parathyroid hormone, and 24-h urine metabolites, were performed. The genotyping of GOX1 gene variants rs6086287, rs2235250, rs2255183, and rs2294303 was performed using a customized TaqMan assay probe by RT-PCR.

RESULT

Parathyroid hormone, serum creatinine, and urine metabolites were significantly elevated in nephrolithiasis compared to healthy individuals. All mutated homozygous genotypes GG (rs6086287), TT (rs2235250), GG (rs2255183), and CC (rs2294303) were significantly associated with a high risk of renal stone disease. Individuals diagnosed with hyperoxaluria and carrying TG (rs6086287), AG (rs2255183), and TT (rs2294303) genotypes have a significantly high risk of renal stone disease. Moreover, haplotype analysis and correlation analysis also confirmed the strong association between genetic variants and nephrolithiasis.

CONCLUSION

Genetic variants of the GOX1 genes were associated with renal stone disease. In the presence of risk genotype and hyperoxaluria, the susceptibility to develop renal stone disease risk gets modulated.

Phytochemicals and bioactive compounds effective against acute myeloid leukemia: A systematic review

This systematic review identified various bioactive compounds which have the potential to serve as novel drugs or leads against acute myeloid leukemia. Acute myeloid leukemia (AML) is a heterogeneous hematopoietic malignancy that arises from the dysregulation of cell differentiation, proliferation, and cell death. The risk factors associated with the onset of AML include long-term exposure to radiation and chemicals such as benzene, smoking, genetic disorders, blood disorders, advancement in age, and others. Although novel strategies to manage AML, including a refinement of the conventional chemotherapy regimens, hypomethylating agents, and molecular targeted drugs, have been developed in recent years, resistance and relapse remain the main clinical problems. In this study, three databases, PubMed/MEDLINE, ScienceDirect, and Google Scholar, were systematically searched to identify various bioactive compounds with antileukemic properties. A total of 518 articles were identified, out of which 59 were viewed as eligible for the current report. From the data extracted, over 60 bioactive compounds were identified and divided into five major groups: flavonoids, alkaloids, organosulfur compounds, terpenes, and terpenoids, and other known and emerging bioactive compounds. The mechanism of actions of the analyzed individual bioactive molecules differs remarkably and includes disrupting chromatin structure, upregulating the synthesis of certain DNA repair proteins, inducing cell cycle arrest and apoptosis, and inhibiting/regulating Hsp90 activities, DNA methyltransferase 1, and histone deacetylase 1.

SPP1 and UMOD gene variants are synergistically associated with risk of renal stone disease

OBJECTIVE

Calcium and oxalate are the most abundant metabolites present in the stone matrix. The SPP1 and UMOD gene has specific expression in kidneys and are involved in various stages of stone formation. Therefore, genetic variants in the SPP1 and UMOD genes may enhance the development of renal stone disease. This study has been designed to understand the association of genetic variants of SPP1 and UMOD genes with renal stone disease.

MATERIALS AND METHOD

A prospective study has been carried out, including 150 renal stone disease patients and 150 healthy individuals. Biochemical parameters were performed, including serum calcium levels, creatinine, parathyroid hormone, and 24-Hour urine metabolites. The genotyping of SPP1 (rs1126616) and UMOD (rs4293393) gene variants were performed using a customized TaqMan probe. T-test was used for continuous biochemical data analysis. The Chi-square test has been applied to assess the risk of a particular genotype associated with renal stone disease. In addition, correlation analysis for biochemical parameters and genetic variants with the renal stone disease has been performed using Shapley additive explanations (SHAP) values calculated with the help of the pycaret library.

RESULT

Renal stone patients had significantly higher levels of parathyroid hormone (93.37 ± 52.78 pg/ml vs 64.67 ± 31.50 pg/ml, P=<0.0001), serum creatinine (0.94 ± 0.38 mg/dl vs 0.77 ± 0.17 mg/dl, P=<0.0001) and 24hr urine metabolites in comparison to the healthy controls. Heterozygous (CT) variant of SPP1 and homozygous (GG) variant of UMOD genes were significantly associated with an increased risk of developing the renal stone disease (p = 0.0100, OR = 2.06, 95 %CI = 1.13-3.75; p=<0.0001, OR = 5.773, 95 % CI = 2.03-16.38, respectively). Individuals with hyperparathyroidism and CC (SPP1) and GG (UMOD) genotypes have a high risk (P = 0.0055, OR = 2.75, 95 %CI = 1.35-5.67; P = 0.0129, OR = 10.03, 95 %CI = 1.60-110.40, respectively) of developing a renal stone. In addition, individuals with hypercalciuria and TT genotype of SPP1 (P = 0.0112, OR = 2.92, 95 % CI = 1.33-6.35), AG genotype of UMOD (P=<0.0001, OR = 5.45, 95 %CI = 2.24-13.96) and GG genotype of UMOD (P=<0.0001, OR = 10.02, 95 %CI = 3.53-24.63) have high risk of developing renal stones. Moreover, Individuals with hyperoxaluria and AG + GG (UMOD) genotype have a greater risk (P=<0.0001, OR = 7.35, 95 % CI = 3.83-13.68) of developing a renal stone. The renal stone risk was persistent (P=<0.0002, OR = 2.44, 95 % CI = 1.52-3.86) when analyzed for the synergistic effect of risk genotypes of SPP1 (CT) and UMOD (GG) gene. Further, correlation analysis also confirmed the strong association between genetic variants and renal stone development.

CONCLUSION

Genetic variants of the SPP1 and UMOD genes were associated with renal stone disease. In the presence of risk genotype and hyperparathyroidism, hypercalciuria, and hyperoxaluria, the susceptibility to develop the renal stone disease risk gets modulated.

Haplotype of CaSR gene is associated with risk of renal stone disease in West Indian population

Calcium is the most abundant metabolite involved in the stone matrix. The CaSR gene controls calcium homeostasis, and genetic variation in the CaSR gene could lead to the development of renal stone disease. Therefore, the current study has been designed to assess the association of genetic variants of CaSR gene polymorphisms with renal stone disease. A single-centric prospective study has been carried out on a total of 300 participants (150 cases and 150 controls). Serum levels of calcium, creatinine, parathyroid hormone, and 24 h urine metabolites were measured. Two polymorphisms, rs1801725 and rs1042636, of the CaSR gene, have been genotyped for each participant. T test, binary logistic regression, and Chi-square analysis were used for statistical analysis. Renal stone patients had significantly higher levels of serum parathyroid hormone, creatinine, and 24-h urine metabolites in comparison to the controls. CaSR gene variants, rs1801725 (GG) and rs1042636 (AA), both have shown significant association with renal stone disease. In addition, individuals having specific genotypes along with metabolic abnormalities such as hypercalcemia and hyperparathyroidism are found to be at a higher significant risk of developing the renal stone disease. In the present study, the haplotype of the CaSR gene has shown an association with renal stone disease. Individuals with hyperparathyroidism and hypercalcemia and risk genotype have a higher susceptibility to developing renal stone disease.

Simultaneous Quantification of Betulinic Acid, Lupeol, and β-Sitosterol in Madhuca longifolia Methanolic Extract of Bark by Liquid Chromatography-Tandem Mass Spectrometric Method

BACKGROUND

Liquid chromatography with tandem mass spectrometry is used widely used for the quantitative analysis of phytoconstituents present in medicinal plants to assess the quality of extract used for different investigations.

OBJECTIVE

A sensitive, precise, and accurate liquid chromatographic method with tandem mass spectrometric detection was developed for simultaneous quantification of lupeol, betulinic acid, and β-sitosterol in the methanolic extract of Madhuca longifolia bark.

METHOD

The three compounds were eluted with a stationary phase Gemini C18 column (50 × 2.0 mm, 3 μm id) and the temperature of the column was maintained by a column oven at 40 ± 0.3°C; mobile phase A (water and 0.1% formic acid) and mobile phase B [acetonitrile-methanol (50+50, v/v) and 0.1% formic acid] were used in a gradient mode and the flow rate was 0.4 mL/min.

RESULTS

With these conditions, the retention time for betulinic acid, lupeol, and β-sitosterol was found to be 1.25, 3.08, and 3.53 minutes, respectively. The total run time was 5.0 min. Detection and quantitation of all three phytoconstituents were carried out by the mass spectrometer, a triple quadrupole equipped with atmospheric pressure chemical ionization, and multiple reaction monitoring using the predominantly positive ion mode and obtained much higher and more stable response nebulizer gas flow at 3.0 L/min. Linear responses were exhibited for all three phytoconstituents with a dynamic linear range of 10-100 μg/mL with the values of the regression coefficient more than 0.995 for betulinic acid, lupeol, and β-sitosterol. The values of percentage RSD for intraday and interday precision were found to be within the accepted limits for analytical methods (<15%). Selectivity, linearity, LOD, LOQ, accuracy, and precision were evaluated for all three phytoconstituents as per International Conference on Harmonization guidelines.

CONCLUSIONS

The proposed method is accurate and sensitive and can be used for the routine quantification of betulinic acid, lupeol, and β-sitosterol from the herbal extract and its poly-herbal formulations.

Efficient extraction of cucurbitacins from Diplocyclos palmatus (L.) C. Jeffrey: Optimization using response surface methodology, extraction methods and study of some important bioactivities

Diplocyclos palmatus (L.) C. Jeffrey is an important medicinal plant used in several reproductive medicines. It serves as a wide source of tetracyclic triterpens called cucurbitacins. Response surface methodology (RSM) with Box-Behnken design (BBD) was studied to optimize the production of cucurbitacins. RSM put forth the ideal conditions such as 1:30 SS ratio (g/mL), 80 rpm (mixing extraction speed), 150 µm mean particle size, 30 min extraction time and 50 °C using chloroform in continuous shaking extraction (CSE) and showed the highest cucurbitacin I (CUI) content (2.345 ± 0.1686 mg/g DW). Similarly, the highest yield of cucurbitacin B (CUB) (1.584 ± 0.15 mg/g DW) was recorded at ideal conditions (1:40 g/mL SS ratio and 60 min time and others similar to CUI). Among the tested extraction methods, the highest CUI, CUB, and CUI + B yield (1.437 ± 0.03, 0.782 ± 0.10, 2.17 ± 0.35 mg/g DW, respectively) as well as promising DPPH radical scavenging activity (25.06 ± 0.1 µgAAE/g DW) were recorded from the SBAE (steam bath assisted extraction). In addition, MAE and UAE revealed the highest inhibition of α-amylase (68.68%) and α-glucosidase (56.27%) enzymes, respectively. Fruit extracts showed potent anticancer activity against breast (MCF-7) and colon (HT-29) cancer cell lines (LC50 - 44.27 and 46.88 µg/mL, respectively). Our study proved that SS ratio, particle size and temperature were the most positively influencing variables and served to be the most efficient for the highest recovery of CUI and CUB. Based on the present study, the fruits of D. palmatus were revealed as a potent antioxidant, anti-diabetic and anticancer bio-resource that could be explored further to develop novel drug to manage diabetes, cancer and oxidative stress related disorders.

Anti-diabetic effects of ethanol extract of Bryonia laciniosa seeds and its saponins rich fraction in neonatally streptozotocin-induced diabetic rats

Context:

Bryonia laciniosa Linn. (Cucurbitaceae) seed is used in traditional medicine for a number of ailments including metabolic disorders.

Aim:

This study evaluated the anti-diabetic action of the ethanol extract of B. laciniosa seeds and saponin fraction of it through its effect on hyperglycemia, dyslipidaemia and oxidative stress in neonatally streptozotocin (n-STZ)-induced diabetic rats (n-STZ diabetic rats).

Materials and Methods:

Ethanol extract (250 and 500 mg/kg; p.o.), saponin fraction (100 and 200 mg/kg; p.o.) and standard drug glibenclamide (3 mg/kg; p.o.) were administered to diabetic rats when the rats were 6 weeks old and continued for 10 consecutive weeks. Effects of ethanol extract and saponin fraction on various biochemical parameters were studied in diabetic rats.

Results:

The treatment with ethanol extract and saponin fraction for 10 weeks decrease in the levels of glucose, triglycerides, cholesterol, high-density lipoprotein, low-density lipoprotein, very low-density lipoprotein, serum urea, serum creatinine and diminished activities of aspartate transaminase, and alanine transaminase. The anti-hyperglycemic nature of B. laciniosa is probably brought about by the extra- the pancreatic mechanism as evidenced from unchanged levels of plasma insulin. B. laciniosa modulated effect of diabetes on the liver malondialdehyde, reduced glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) activity. Administration of ethanol extract and saponin fraction to diabetic rats showed a significant reversal of disturbed antioxidant status. Significant increase in SOD, CAT, and levels of GSH was observed in treated n-STZ diabetic rats.

Conclusion:

The present study reveals the efficacy of B. laciniosa seed extract and its saponin fraction in the amelioration of n-STZ diabetic rats.

Evaluating the success of Nd: YAG laser ablation in the treatment of recalcitrant verruca plantaris and a cautionary note about local anaesthesia on the plantar aspect of the foot

BACKGROUND

There are various methods advocated for the treatment of verruca plantaris. However, many verrucas do not respond to simple treatment.

OBJECTIVE

This study presents our results using Nd: YAG laser ablation therapy for such recalcitrant cases.

METHODS

We performed a retrospective audit by sending a questionnaire to all patients with recalcitrant verrucas who had been treated with Nd:YAG laser ablation over the previous 12 months. The questionnaire asked whether treatment had been successful, successful but new lesions had emerged, partially successful with improvement or unsuccessful. A Fontana Nd:YAG laser was used at the following specifications; long pulsed mode with pulse width 25 ms, frequency 1.0 Hz; fluence 240 J/cm(2) and spot size 2 mm. Some patients requested local anaesthesia and had direct infiltration with 0.5% plain lidocaine.

RESULTS

Fifty-three of the original 87 patients responded (60.9% response rate) with a male to female ratio of 24:29, mean age of 47 years and an age range between 22-72. Thirty-seven patients reported complete success post treatment (69.8%) and a further five reported improvement. The remaining 11 felt their treatment was unsuccessful. The cure rate was 81.8% in unilateral single cases, 68.1% in unilateral multiple cases and 65% in bilateral cases. Ten patients requested sublesional lidocaine injections of which 4 had skin breakdown after Nd: YAG ablation.

CONCLUSION

Nd:YAG laser ablation is effective in the treatment of recalcitrant verruca plantaris. However, we caution against the use of direct local anaesthesia infiltration before laser treatment.

Antiurolithiatic and antioxidant activity of Hordeum vulgare seeds on ethylene glycol-induced urolithiasis in rats

OBJECTIVE

The objective was to investigate the antiurolithiatic and antioxidant activity of ethanolic extract of Hordeum vulgare seeds (EHV) on ethylene glycol-induced urolithiasis in Wistar albino rats.

MATERIALS AND METHODS

Urolithiasis was produced in Wistar albino rats by adding 0.75% v/v ethylene glycol (EG) to drinking water for 28 days. The ethanolic extract of Hordeum vulgare seeds (EHV) was assessed for its curative and preventive action in urolithiasis. In preventive treatment, the EHV given from 1st day to 28th day, while in the curative regimen, the EHV was given from 15th day to 28th day. Various renal functional and injury markers such as urine volume, calcium, phosphate, uric acid, magnesium, urea, and oxalate were evaluated using urine, serum, and kidney homogenate. Antioxidant parameters such as lipid peroxidation, superoxide dismutase, and catalase were also determined.

RESULTS

The EHV treatment (both preventive and curative) increased the urine output significantly compared to the control. The EHV treatment significantly reduced the urinary excretion of the calcium, phosphate, uric acid, magnesium, urea, and oxalate and increased the excretion of citrate compared to EG control. The increased deposition of stone forming constituents in the kidneys of calculogenic rats were significantly lowered by curative and preventive treatment with EHV. It was also observed that the treatment with EHV produced significant decrease in lipid peroxidation, and increased levels of superoxide dismutase and catalase.

CONCLUSION

These results suggest the usefulness of ethanolic extract of Hordeum vulgare seeds as an antiurolithiatic and antioxidant agent.

Preparation and characterization of spray-dried mucoadhesive microspheres of ketorolac for nasal administration

The objective of this investigation was to prepare mucoadhesive microspheres of ketorolac for nasal delivery to avoid gastrointestinal side effects of conventional dosage form. Mucoadhesive microspheres were prepared using carbopol, polycarbophil and chitosan as polymer by spray drying method. The process and formulation parameters were varied to study the effect on the yield and particle size. Microspheres were characterized for surface morphology, encapsulation efficiency, swelling behavior, mucoahesion properties, interaction studies using FTIR and DSC, in vitro drug release, ex vivo nasal cilio toxicity studies and in vivo anti-inflammatory and analgesic activity. Prepared microspheres were discrete, bulky, free flowing and showed an average encapsulation efficiency ranging from 79-92%. The results showed that the process parameters significantly affect the particle size (10.29-16.75 μm) and yield of microspheres (36.53-56.69%). Interaction studies revealed that there were no drug to polymer interactions. Prepared microspheres exhibited good swelling and mucoadhesion strength which confined the strong mucoadhesive property of microspheres. Ketorolac release from the microspheres was extended up to 8 h and exhibited fickian drug release kinetics with best fit to higuchi model. The drug loaded microspheres were found to be nontoxic to nasal mucosa. The anti-inflammatory and analgesic effects of formulation showed a significant increase (p < 0.05) in percent inhibition value of up to 8 h when compared with ketorolac. In conclusion, spray dried microspheres based on chitosan could be suitable nasal delivery system for the administration of ketorolac.

Gelastic syncope: an unusual condition

Gelastic syncope or laughter-induced syncope is a rare disease often misdiagnosed as narcolepsy or cataplexy. We report a 54-year-old man with syncopal episodes. Each episode started after laughter, leading to light-headedness with blurring of vision and loss of consciousness for a few seconds. The episodes resolved spontaneously. The treatment of gelastic syncope is the same as that for neurally mediated syncope.

Prevalence of hiatal hernia by blinded multidetector CT in patients with idiopathic pulmonary fibrosis

Hiatal hernia (HH) is associated with gastro-oesophageal reflux (GOR) and/or GOR disease and may contribute to idiopathic pulmonary fibrosis (IPF). We hypothesised that HH evaluated by computed tomography is more common in IPF than in asthma or chronic obstructive pulmonary disease (COPD), and correlates with abnormal GOR measured by pH probe testing. Rates of HH were compared in three cohorts, IPF (n=100), COPD (n=60) and asthma (n=24), and evaluated for inter-observer agreement. In IPF, symptoms and anti-reflux medications were correlated with diffusing capacity of the lung for carbon monoxide (D(L,CO)) and composite physiologic index (CPI). HH was correlated with pH probe testing in IPF patients (n=14). HH was higher in IPF (39%) than either COPD (13.3%, p=0.00009) or asthma (16.67%, p=0.0139). The HH inter-observer κ agreement was substantial in IPF (κ=0.78) and asthma (κ=0.86), and moderate in COPD (κ=0.42). In IPF, HH did not correlate with lung function, except in those on anti-reflux therapy, who had a better D(L,CO) (p<0.03) and CPI (p<0.04). HH correlated with GOR as measured by DeMeester scores (p<0.04). HH is more common in IPF than COPD or asthma. In an IPF cohort, HH correlated with higher DeMeester scores, confirming abnormal acid GOR. Presence of HH alone was not associated with decreased lung function.

Development and characterization of mucoadhesive microspheres for nasal delivery of ketorolac

The objective of the present investigation was to prepare mucoadhesive microspheres of ketorolac for nasal administration by means of a solvent evaporation technique using carbopol (CP), polycarbophil (PL) and chitosan (CS) as mucoadhesive polymers. The prepared microspheres were characterized for morphology, swelling behavior, mucoadhesion, interaction studies, drug encapsulation efficiency, in vitro drug release, release kinetics, and ex vivo nasal cilio toxicity studies. The effects of various process variables on the particle size of the microspheres were investigated. Drug encapsulation efficiency and particle size of the microspheres ranged from 52-78% w/w and 14-46 microm respectively. Interaction studies revealed that there were no drug-polymer interactions. The in vitro release profiles showed prolonged-release of the drug. In vitro release data showed a good fit with the Higuchi model, and indicated Fickian diffusion. No severe damage was found to the integrity of nasal mucosa after ex vivo experiments.

The prognosis of severe lupus nephritis based on the Modification of Diet in Renal Disease (MDRD) study estimated glomerular filtration rate

The level of renal function at biopsy is predictive of outcome in patients with severe lupus nephritis (SLN). While renal function has been based on serum creatinine (SCr) alone, measuring the estimated glomerular filtration rate (eGFR) utilizing the Modification of Diet in Renal Disease (MDRD) Study equation has been found to be more accurate. The MDRD eGFR (ml/min/1.73 m(2)) at biopsy was calculated in 86 patients with SLN and patients were categorized based on eGFR: ≥60 (33 pts), 59-30 (33 pts) and <30 (20 pts). An eGFR was <60 in 18% of patients with a normal SCr. After 120 ± 65 months of follow-up, attainment of a complete remission (76% versus 30% versus 10%, p < 0.0001) and patient survival without end-stage renal disease (ESRD; 10 year survival: 85% versus 45% versus 14%, p < 0.0001 overall) was highest in patients with an eGFR ≥60 and lowest in those with an eGFR <30. The long-term prognosis for patients with severe lupus nephritis and an eGFR ≥60 was extremely good. Since the prognosis for patients with an eGFR <60 was poor even in those patients with a normal SCr, renal function is more accurately determined by the MDRD eGFR.

Cholesterol and non-cholesterol sterol transporters: ABCG5, ABCG8 and NPC1L1: a review

1. Whole-body sterol (cholesterol and xenosterol) balance is delicately regulated by the gastrointestinal tract and liver, which control sterol absorption and excretion, respectively, in addition to the contribution to the cholesterol pool by whole-body cholesterol synthesis. In the past ten years enormous strides have been made not only in establishing that specific transporters mediate the entry and exit of sterols and how these may regulate selective sterol access to the body pools, but also in how these pathways operate to integrate these physiological pathways. 2. The entry of sterols from the gastrointestinal and biliary canalicular lumen into the body is mediated by NPC1L1, which was discovered by a novel method, via a genomics-bioinformatics approach. 3. Identification of the genetic basis responsible for causing sitosterolaemia, characterized by plant sterol accumulation, led to the identification of two half-transporters (ABCG5 and ABCG8) that normally efflux plant sterols (and cholesterol) into the intestinal and biliary lumen for faecal excretion. 4. The objective of this review is to provide up-to-date knowledge on genomics, proteomics and function of these two transporter systems.

Sitosterolaemia: pathophysiology, clinical presentation and laboratory diagnosis

Sitosterolaemia is an extremely rare autosomal recessive disease, the key feature of which is the impairment of pathways that normally prevent absorption and retention of non-cholesterol sterols, for example plant sterols and shellfish sterols. The clinical manifestations are akin to familial hypercholesterolaemia (such as presence of tendon xanthomas and premature atherosclerosis), but with "normal to moderately elevated" cholesterol levels. The gene(s) causing sitosterolaemia was mapped to the STSL locus on human chromosome 2p21, and mutations in either of the two genes that comprise this locus, ABCG5 or ABCG8, cause this disease. Exact prevalence is unknown, but there are estimated to be 80-100 cases around the world. This rare disease has shed light into the molecular mechanisms that control sterol trafficking in the enterocyte and hepatocyte; ABCG5 and ABCG8 heterodimerise to form a sterol efflux transporter in the liver and intestine. In this review the pathophysiology, clinical manifestations and approach to clinical and laboratory diagnosis of this disease are described.

Recent insights into the Smith-Lemli-Opitz syndrome

Recent insights into the Smith-Lemli-Opitz syndrome. The Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive multiple congenital anomaly/mental retardation disorder caused by an inborn error of post-squalene cholesterol biosynthesis. Deficient cholesterol synthesis in SLOS is caused by inherited mutations of 3beta-hydroxysterol-Delta7 reductase gene (DHCR7). DHCR7 deficiency impairs both cholesterol and desmosterol production, resulting in elevated 7DHC/8DHC levels, typically decreased cholesterol levels and, importantly, developmental dysmorphology. The discovery of SLOS has led to new questions regarding the role of the cholesterol biosynthesis pathway in human development. To date, a total of 121 different mutations have been identified in over 250 patients with SLOS who represent a continuum of clinical severity. Two genetic mouse models have been generated which recapitulate some of the developmental abnormalities of SLOS and have been useful in elucidating the pathogenesis. This mini review summarizes the recent insights into SLOS genetics, pathophysiology and potential therapeutic approaches for the treatment of SLOS.

Sitosterolaemia in Switzerland: molecular genetics links the US Amish-Mennonites to their European roots

Sitosterolaemia is a rare autosomal recessive disease characterized by increased intestinal absorption of plant sterols, decreased hepatic excretion into bile and elevated concentrations in plasma phytosterols. Homozygous or compound heterozygous loss of function mutations in either of the ATP-binding cassette (ABC) proteins ABCG5 and ABCG8 explain the increased absorption of plant sterols. Here we report a Swiss index patient with sitosterolaemia, who presented with the classical symptoms of xanthomas, but also had mitral and aortic valvular heart disease. Her management over the last 20 years included a novel therapeutic approach of high-dose cholesterol feeding that was semi-effective. Mutational and extended haplotype analyses showed that our patient shared this haplotype with that of the Amish-Mennonite sitosterolaemia patients, indicating they are related ancestrally.

Anthrax lethal factor inhibition

The primary virulence factor of Bacillus anthracis is a secreted zinc-dependent metalloprotease toxin known as lethal factor (LF) that is lethal to the host through disruption of signaling pathways, cell destruction, and circulatory shock. Inhibition of this proteolytic-based LF toxemia could be expected to provide therapeutic value in combination with an antibiotic during and immediately after an active anthrax infection. Herein is shown the crystal structure of an intimate complex between a hydroxamate, (2R)-2-[(4-fluoro-3-methylphenyl)sulfonylamino]-N-hydroxy-2-(tetrahydro-2H-pyran-4-yl)acetamide, and LF at the LF-active site. Most importantly, this molecular interaction between the hydroxamate and the LF active site resulted in (i) inhibited LF protease activity in an enzyme assay and protected macrophages against recombinant LF and protective antigen in a cell-based assay, (ii) 100% protection in a lethal mouse toxemia model against recombinant LF and protective antigen, (iii) approximately 50% survival advantage to mice given a lethal challenge of B. anthracis Sterne vegetative cells and to rabbits given a lethal challenge of B. anthracis Ames spores and doubled the mean time to death in those that died in both species, and (iv) 100% protection against B. anthracis spore challenge when used in combination therapy with ciprofloxacin in a rabbit "point of no return" model for which ciprofloxacin alone provided 50% protection. These results indicate that a small molecule, hydroxamate LF inhibitor, as revealed herein, can ameliorate the toxemia characteristic of an active B. anthracis infection and could be a vital adjunct to our ability to combat anthrax.

Ezetimibe effectively reduces plasma plant sterols in patients with sitosterolemia

BACKGROUND

Sitosterolemia is a recessively inherited disorder that results from mutations in either ABCG5 or G8 proteins, with hyperabsorption of dietary sterols and decreased hepatic excretion of plant sterols and cholesterol. As a consequence of markedly elevated plasma and tissue sitosterol and campesterol levels, premature atherosclerosis develops.

METHODS AND RESULTS

In this multicenter, double-blind, randomized, placebo-controlled study, we examined whether treatment with ezetimibe, an inhibitor of cholesterol absorption, reduces plant sterol levels in patients with sitosterolemia. After a 3-week placebo run-in, 37 patients were randomized to receive placebo (n=7) or ezetimibe 10 mg/d (n=30) for 8 weeks. Sitosterol concentrations decreased by 21% (P<0.001) in patients treated with ezetimibe compared with a nonsignificant 4% rise in those on placebo (between-group P<0.001). The reduction in sitosterol from baseline was progressive, with further decline observed at each subsequent biweekly visit. Campesterol also progressively declined, with a mean decrease after 8 weeks of 24% with ezetimibe and a mean increase of 3% with placebo treatment (between-group P<0.001). Reductions in plant sterol concentrations were similar irrespective of whether patients were undergoing concomitant treatment with resin or statin. Reductions in total sterols and apolipoprotein B were also observed. Ezetimibe was well tolerated, with no serious treatment-related adverse events or discontinuations due to adverse events being reported.

CONCLUSIONS

Ezetimibe produced significant and progressive reductions in plasma plant sterol concentrations in patients with sitosterolemia, consistent with the hypothesis that ezetimibe inhibits the intestinal absorption of plant sterols as well as cholesterol, leading to reductions in plasma concentrations.

Oesophageal atresia: a simplified approach to early management

Management following the repair of oesophageal atresia (OA) with tracheooesophageal fistula (TOF) in the past included the routine use of an intercostal chest drain, a gastrostomy, or a transanastomotic tube (TAT) for enteral nutrition and a routine contrast swallow (CS) before oral feeds. There has been a trend towards simplification of the management, but this is not universal. The aim of this study was to evaluate the safety of a simplified management regime in infants undergoing primary repair of OA in a retrospective case note review of infants undergoing surgery for OA with TOF under the care of one consultant over a 12-year period. Intercostal chest drains, TATs, and CSs were not routinely used. Early enteral feeding was initiated and oral feeding was allowed in babies of adequate birth weight (BW) and gestation. A CS was only performed when there were specific anastomotic concerns. Parameters recorded included demographic details, time to first enteral feed by tube or mouth, time to full oral feeds, and complications. Forty patients were studied; 17 were managed without (group 1) and 23 with (group 2) a TAT. Sex distribution, gestational age, and BW were comparable in the two groups. In group 1, the time to the establishment of full oral feeds was 2-8 days (average 3.9). Four infants developed strictures; 2 were managed with dilatation alone and 2 required surgery. In group 2, the time to the establishment of full enteral feeds was 2-12 days (average 5.9). Four patients developed strictures; 2 underwent an anti-reflux procedure and a 3rd resection of a cartilaginous remnant. There was 1 death in a patient with intractable cardiac failure. The majority of infants with OA and TOF can thus be safely managed without routine chest drainage or CS. A sizeable minority do not require a TAT. Early introduction of oral feeds in the non-TAT group is not associated with an increased complication rate.

7-Dehydrocholesterol-dependent proteolysis of HMG-CoA reductase suppresses sterol biosynthesis in a mouse model of Smith-Lemli-Opitz/RSH syndrome

Smith-Lemli-Opitz/RSH syndrome (SLOS), a relatively common birth-defect mental-retardation syndrome, is caused by mutations in DHCR7, whose product catalyzes an obligate step in cholesterol biosynthesis, the conversion of 7-dehydrocholesterol to cholesterol. A null mutation in the murine Dhcr7 causes an identical biochemical defect to that seen in SLOS, including markedly reduced tissue cholesterol and total sterol levels, and 30- to 40-fold elevated concentrations of 7-dehydrocholesterol. Prenatal lethality was not noted, but newborn homozygotes breathed with difficulty, did not suckle, and died soon after birth with immature lungs, enlarged bladders, and, frequently, cleft palates. Despite reduced sterol concentrations in Dhcr7(-/-) mice, mRNA levels for 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the rate-controlling enzyme for sterol biosynthesis, the LDL receptor, and SREBP-2 appeared neither elevated nor repressed. In contrast to mRNA, protein levels and activities of HMG-CoA reductase were markedly reduced. Consistent with this finding, 7-dehydrocholesterol accelerates proteolysis of HMG-CoA reductase while sparing other key proteins. These results demonstrate that in mice without Dhcr7 activity, accumulated 7-dehydrocholesterol suppresses sterol biosynthesis posttranslationally. This effect might exacerbate abnormal development in SLOS by increasing the fetal cholesterol deficiency.

Dietary cholesterol absorption; more than just bile

Absorption of dietary cholesterol from the intestine is an important part of cholesterol homeostasis and represents the first step that allows dietary cholesterol to exert its metabolic effects. Although the role of bile salts in the initial absorption of dietary cholesterol, by the formation of emulsions, is readily appreciated, the recognition that other molecular mechanisms might govern this process is only recently gaining momentum. Not only does the intestine regulate the amount of dietary cholesterol that enters the body; it is very selective with regard to the sterols that are allowed in. The human intestine is responsible for absorbing a significant amount of cholesterol each day. In addition to approximately 0.5 g d(-1) of dietary cholesterol, many other sterols are also present in almost equal abundance in the normal diet. Approximately 0.4 g of plant sterols, such as sitosterol, brassicasterol and avanesterol, are also present. However, the human body seems to allow only cholesterol to enter and remain in the body, with almost negligible amounts of plant sterols being retained. That specific molecular mechanisms are responsible for this behavior is supported by the identification of the genetic defect(s) in a rare disorder, beta-sitosterolemia (MIM 210250), where this process is disrupted. Such studies are now beginning to throw light on sterol absorption and excretion and elucidate the molecular mechanisms that govern these processes.

Fine-mapping, mutation analyses, and structural mapping of cerebrotendinous xanthomatosis in U.S. pedigrees

Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive disorder of bile acid biosynthesis. Clinically, CTX patients present with tendon xanthomas, juvenile cataracts, and progressive neurological dysfunction and can be diagnosed by the detection of elevated plasma cholestanol levels. CTX is caused by mutations affecting the sterol 27-hydroxylase gene (CYP27 ). CTX has been identified in a number of populations, but seems to have a higher prevalence in the Japanese, Sephardic Jewish, and Italian populations. We have assembled 12 previously unreported pedigrees from the United States. The CYP27 locus had been previously mapped to chromosome 2q33-qter. We performed linkage analyses and found no evidence of genetic heterogeneity. All CTX patients showed segregation with the CYP27 locus, and haplotype analysis and recombinant events allowed us to precisely map CYP27 to chromosome 2q35, between markers D2S1371 and D2S424. Twenty-three mutations were identified from 13 probands analyzed thus far; 11 were compound heterozygotes and 2 had homozygous mutations. Of these, five are novel mutations [Trp100Stop, Pro408Ser, Gln428Stop, a 10-base pair (bp) deletion in exon 1, and a 2-bp deletion in exon 6 of the CYP27 gene]. Three-dimensional structural modeling of sterol 27-hydroxylase showed that, while the majority of the missense mutations disrupt the heme-binding and adrenodoxin-binding domains critical for enzyme activity, two missense mutations (Arg94Trp/Gln and Lys226Arg) are clearly located outside these sites and may identify a potential substrate-binding or other protein contact site.

Spectrum of Delta(7)-dehydrocholesterol reductase mutations in patients with the Smith-Lemli-Opitz (RSH) syndrome

The Smith-Lemli-Opitz syndrome (SLOS; also known as the RSH syndrome) is an autosomal recessive genetic disorder, leading to characteristic multi-organ developmental abnormalities, dysmorphic facies, limb malformations and mental retardation. Mutations in the gene for Delta(7)-dehydrocholesterol reductase (Delta(7)-reductase), which catalyzes the last step in cholesterol biosynthesis, cause the disease. We screened 32 patients with SLOS, 28 from the USA and four from Sweden. Twenty-two different nucleotide changes, predicted to be disease-causing mutations, were identified; 20 missense mutations, one nonsense mutation and one splice-site mutation involving the exon 9 acceptor site (IVS8 -1G-->C) were detected. All probands were heterozygous for mutations. Twelve of these mutations have not been reported previously, including missense mutations L148R, F168I, D175H, P179L, P243R, F284L, N287K, F302L, R404S, Y462H, R469P and one nonsense mutation W37X [corrected]. Coupled with previously reported mutations, these findings bring the total of different Delta(7)-reductase mutations to 36. These are distributed throughout the coding sequence of the Delta(7)-reductase gene except exons 3 and 5, with a clustering in exon 9. Three mutations account for 54% of those observed in our cohort, the splice acceptor site mutation IVS8 -1G-->C (22/64 alleles, 34%), T93M (8/64, 12.5%) and V326L (5/64, 7.8%). Severity of SLOS was negatively correlated with both plasma cholesterol and relative plasma cholesterol, but not with 7-dehydrocholesterol, the immediate precursor, confirming previous observations. However, no correlation was observed between mutations and phenotype, suggesting that the degree of severity may be affected by other factors. We estimate that between 33 and 42% of the variation in the SLOS severity score is accounted for by variation in plasma cholesterol. Thus, factors other than plasma cholesterol are additionally involved in determining severity.

Microsomal triglyceride transfer protein expression during mouse development

Feto-maternal transfer of lipophilic nutrients is an important factor in the normal development of the fetus and may be mediated by lipoproteins as carriers of these nutrients. Two proteins that may be important in this process are apolipoprotein B (apoB, the major structural protein of secreted lipoproteins) and microsomal triglyceride transfer protein (MTP) whose normal activity is required for the secretion of apoB-containing lipoproteins. Although no abnormalities of conception and embryonic lethality are known in humans who inherit genetic deficiencies of either of these proteins, homozygous mice bearing knockouts of either apoB or MTP show early embryonic lethality. To characterize the ontogeny of MTP expression during embryonic mouse development, we have used in situ hybridization to characterize the pattern of expression. By using microwave heating of tissue sections to optimize hybridization, we show that there is robust MTP expression in the yolk sac tissues followed by expression in the primordial liver cell nests as early as day 9 post-coitum (E9.5). Intestinal expression is detected around E12.5 and attains full adult expression patterns by E14.5. No expression in any other tissues was observed, including developing heart, kidney, placenta, and maternal decidua. Thus the pattern of MTP expression is compatible with a role in the transfer of lipophilic nutrients from the yolk sac, prior to hepatic development and to the liver, once the circulatory system has been established.

Removal of Foscarnet by hemodialysis using dialysate-side values

Foscarnet is an antiviral agent widely used in the treatment of cytomegalovirus (CMV) infection. We describe a cardiac transplant patient, who while being maintained with hemodialysis because of tobramycin-induced acute renal failure, was given Foscarnet for disseminated CMV infection. Using dialysate-side clearance methodology, we found the dialyzer clearance of Foscarnet to be in the order of 89 ml/min.

Detection of a common mutation in the RSH or Smith-Lemli-Opitz syndrome by a PCR-RFLP assay: IVS8-G-->C is found in over sixty percent of US propositi

The RSH or Smith-Lemli-Opitz syndrome (SLOS) is a relatively common autosomal recessive disorder of cholesterol biosynthesis resulting from a deficiency of the enzyme 7-dehydrocholesterol delta7-reductase (7-DHCR). Mutations in 7-DHCR gene cause SLOS. Among these, a G-->C transversion in the splice acceptor site of exon 9 (IVS8-1G-->C) was suspected to be a frequent mutation, having been detected in about 18% of SLOS patients so far. This mutation results in the elimination of a AlwN1 restriction endonuclease site. We report a simple PCR-RFLP assay to detect the IVS8-1G-->C mutation. Using this method, we identified the IVS8-1G-->C mutation in 21 of 33 SLOS propositi. This mutation was detected in one of 90 normal adult Caucasian Americans; but not among 121 Africans from Sierra Leone, 120 Caucasians from Finland, 95 Chinese or 103 Japanese adults. The results of this study provide further evidence that IVS8-1G-->C transversion is a very common mutation in SLOS patients from the US and that the carrier rate in US caucasians may be high. The simple PCR-RFLP assay developed makes identification of this mutation convenient for diagnosis and for carrier detection.

Cyclosporin-induced dyslipoproteinemia is associated with selective activation of SREBP-2

The use of cyclosporin A has contributed greatly to the success of organ transplantation. However, cyclosporin-associated side effects of hypertension, nephrotoxicity, and dyslipoproteinemia have tempered these benefits. Cyclosporin-induced dyslipoproteinemia may be an important risk factor for the accelerated atherosclerosis observed posttransplantation. Using a mouse model, we treated Swiss-Webster mice for 6 days with a daily dose of 20 microg/g body wt of cyclosporin and observed significant elevations of plasma cholesterol, triglyceride, and apolipoprotein B (apoB) levels relative to vehicle-alone treated control animals. Measurement of the rate of secretion of very low-density lipoprotein (VLDL) by the liver in vivo showed that cyclosporin treatment led to a significant increase in the rate of hepatic VLDL triglyceride secretion. Total apoB secretion was unaffected. Northern analysis showed that cyclosporin A treatment increased the abundance of hepatic mRNA levels for a number of key genes involved in cholesterol biosynthesis relative to vehicle-alone treated animals. Two key transcriptional factors, sterol regulatory element-binding protein (SREBP)-1 and SREBP-2, also showed differential expression; SREBP-2 expression was increased at the mRNA level, and there was an increase in the active nuclear form, whereas the mRNA and the nuclear form of SREBP-1 were reduced. These results show that the molecular mechanisms by which cyclosporin causes dyslipoproteinemia may, in part, be mediated by selective activation of SREBP-2, leading to enhanced expression of lipid metabolism genes and hepatic secretion of VLDL triglyceride.

Saline-induced dilutional acidosis in a maintenance hemodialysis patient

A patient with end-stage renal disease developed severe hyperchloremic acidosis (venous serum total CO2 level of 10 mmol/L) after treatment with 16 L of isotonic saline. Analysis of this case and published literature indicates that dilutional acidosis may result when very large volumes of isotonic saline are administered intravenously, especially in patients with impaired or absent renal function.

A gene for congenital generalized lipodystrophy maps to human chromosome 9q34

Congenital generalized lipodystrophy (CGL, Berardinelli-Seip Syndrome, OMIM # 269700) is a rare autosomal recessive disorder characterized by near complete absence of adipose tissue from birth. Affected individuals have marked insulin resistance, hypertriglyceridemia and acanthosis nigricans, and develop diabetes mellitus during teenage years. The genetic defect for CGL is unknown. A semi-automated genome-wide scan with a set of highly polymorphic short tandem repeats (STR) was carried out in 17 well-characterized pedigrees and identified a locus for CGL to chromosome 9q34. The maximum two-point lod score obtained was 3.6 at D9S1818 (theta(max) = 0.05). There was evidence for genetic heterogeneity (alpha = 0.73) and 2 of the pedigrees were unlinked. Multipoint linkage analysis excluding the 2 unlinked families yielded a peak lod score of 5.4 between loci D9S1818 and D9S1826. The CGL1 critical region harbors a plausible candidate gene encoding the retinoid X receptor alpha (RXRA) that plays a central role in adipocyte differentiation. Identification of the CGL gene(s) will contribute to our understanding of the adipocyte differentiation and elucidation of the mechanisms of insulin resistance in disorders of adipose tissue.

Mapping a gene involved in regulating dietary cholesterol absorption. The sitosterolemia locus is found at chromosome 2p21

The molecular mechanisms regulating the amount of dietary cholesterol retained in the body as well as the body's ability to selectively exclude other dietary sterols are poorly understood. Studies of the rare autosomal recessively inherited disease sitosterolemia (OMIM 210250) may shed some light on these processes. Patients suffering from this disease appear to hyperabsorb both cholesterol and plant sterols from the intestine. Additionally, there is failure of the liver's ability to preferentially and rapidly excrete these non-cholesterol sterols into bile. Consequently, people who suffer from this disease have very elevated plasma plant sterol levels and develop tendon and tuberous xanthomas, accelerated atherosclerosis, and premature coronary artery disease. Identification of this gene defect may therefore throw light on regulation of net dietary cholesterol absorption and lead to an advancement in the management of this important cardiovascular risk factor. By studying 10 well-characterized families with this disorder, we have localized the genetic defect to chromosome 2p21, between microsatellite markers D2S1788 and D2S1352 (maximum lodscore 4.49, theta = 0.0).