Novel Perspectives in Chronic Kidney Disease-Specific Cardiovascular Disease

Chronic kidney disease (CKD) affects > 10% of the global adult population and significantly increases the risk of cardiovascular disease (CVD), which remains the leading cause of death in this population. The development and progression of CVD-compared to the general population-is premature and accelerated, manifesting as coronary artery disease, heart failure, arrhythmias, and sudden cardiac death. CKD and CV disease combine to cause multimorbid cardiorenal syndrome (CRS) due to contributions from shared risk factors, including systolic hypertension, diabetes mellitus, obesity, and dyslipidemia. Additional neurohormonal activation, innate immunity, and inflammation contribute to progressive cardiac and renal deterioration, reflecting the strong bidirectional interaction between these organ systems. A shared molecular pathophysiology-including inflammation, oxidative stress, senescence, and hemodynamic fluctuations characterise all types of CRS. This review highlights the evolving paradigm and recent advances in our understanding of the molecular biology of CRS, outlining the potential for disease-specific therapies and biomarker disease detection.

Tolerogenic dendritic cells protect against acute kidney injury

Ischemia reperfusion injury is a common precipitant of acute kidney injury that occurs following disrupted perfusion to the kidney. This includes blood loss and hemodynamic shock, as well as during retrieval for deceased donor kidney transplantation. Acute kidney injury is associated with adverse long-term clinical outcomes and requires effective interventions that can modify the disease process. Immunomodulatory cell therapies such as tolerogenic dendritic cells remain a promising tool, and here we tested the hypothesis that adoptively transferred tolerogenic dendritic cells can limit kidney injury. The phenotypic and genomic signatures of bone marrow-derived syngeneic or allogeneic, Vitamin-D3/IL-10-conditioned tolerogenic dendritic cells were assessed. These cells were characterized by high PD-L1:CD86, elevated IL-10, restricted IL-12p70 secretion and a suppressed transcriptomic inflammatory profile. When infused systemically, these cells successfully abrogated kidney injury without modifying infiltrating inflammatory cell populations. They also provided protection against ischemia reperfusion injury in mice pre-treated with liposomal clodronate, suggesting the process was regulated by live, rather than reprocessed cells. Co-culture experiments and spatial transcriptomic analysis confirmed reduced kidney tubular epithelial cell injury. Thus, our data provide strong evidence that peri-operatively administered tolerogenic dendritic cells have the ability to protect against acute kidney injury and warrants further exploration as a therapeutic option. This technology may provide a clinical advantage for bench-to-bedside translation to affect patient outcomes.

Disease-modifying interactions between chronic kidney disease and osteoarthritis: a new comorbid mouse model

OBJECTIVE

The prevalence of comorbid chronic kidney disease (CKD) and osteoarthritis (OA) is increasing globally. While sharing common risk factors, the mechanism and consequences of concurrent CKD-OA are unclear. The aims of the study were to develop a preclinical comorbid model, and to investigate the disease-modifying interactions.

METHODS

Seventy (70) male 8-10 week-old C57BL/6 mice were subjected to 5/6 nephrectomy (5/6Nx)±destabilisation of medial meniscus (DMM) or sham surgery. OA pathology and CKD were assessed 12 weeks postinduction by blinded histology scoring, micro-CT, immunohistochemistry for osteoclast and matrix metalloproteinase (MMP)-13 activity, and serum analysis of bone metabolic markers.

RESULTS

The 5/6Nx model recapitulated characteristic features of CKD, with renal fibrosis and deranged serum alkaline phosphatase, calcium and phosphate. There was no histological evidence of cartilage pathology induced by 5/6Nx alone, however, synovial MMP-13 expression and subchondral bone osteoclastic activity were increased (p<0.05), with accompanying reductions (p<0.05) in subchondral trabecular bone, bone volume and mineral density. DMM significantly (p<0.05) increased tibiofemoral cartilage damage, subchondral bone sclerosis, marginal osteophytes and synovitis, in association with increased cartilage and synovial MMP-13. DMM alone induced (p<0.05) renal fibrosis, proteinuria and increased (p<0.05) 5/6Nx-induced serum urea. However, DMM in 5/6Nx-mice resulted in significantly reduced (p<0.05) cartilage pathology and marginal osteophyte development, in association with reduced subchondral bone volume and density, and inhibition of 5/6Nx-induced subchondral bone osteoclast activation.

CONCLUSION

This study assessed a world-first preclinical comorbid CKD-OA model. Our findings demonstrate significant bidirectional disease-modifying interaction between CKD and OA.

Feasibility, acceptability and potential efficacy of a virtual physical activity program in primary and secondary schools in New South Wales, Australia: A quasi-experimental study

ISSUE ADDRESSED

Child and youth participation in physical activity (PA) is fundamental for healthy development and obesity prevention. Government policy requires schools to offer 150 minutes of PA each week, however compliance is low. Race around Australia (RAA) is a New South Wales (NSW) Department of Education, virtual PA program aimed at assisting schools in meeting the PA guidelines.

METHODS

A pre- and post-intervention, quasi-experimental study was conducted using a mixed-methods approach comprising teacher interviews, a student questionnaire and a 1.6 kilometre (km) timed run. Data were collected from April to September 2021 among students and teachers in Grades 5 to 8, from 10 schools in NSW, Australia.

RESULTS

The analytical sample included data from 918 students and 17 teachers. The RAA program was deemed feasible and acceptable in primary schools, whereas there were several systemic and intrapersonal barriers to implementation success for secondary schools. In primary schools, RAA increased PA opportunities and the 1.6 km timed runs revealed a statistically significant treatment by time effect in favour of the intervention group for cardiorespiratory fitness (-36.91 seconds, 95% CI [-63.14, -10.68], P = .006).

CONCLUSIONS

RAA has demonstrated feasibility and potential efficacy in improving cardiorespiratory fitness. We recommend that program refinement be made to deliver an intervention that addresses the unique barriers of the secondary school setting through a multi-level ecological approach. SO WHAT?: Despite evident benefits, implementation of PA initiatives in the school setting reveals many challenges. Stronger consideration of the Health Promotion with Schools Framework is evidently needed.

Biomarkers in Cardiorenal Syndrome and Potential Insights Into Novel Therapeutics

Heart and kidney failure often co-exist and confer high morbidity and mortality. The complex bi-directional nature of heart and kidney dysfunction is referred to as cardiorenal syndrome, and can be induced by acute or chronic dysfunction of either organ or secondary to systemic diseases. The five clinical subtypes of cardiorenal syndrome are categorized by the perceived primary precipitant of organ injury but lack precision. Traditional biomarkers such as serum creatinine are also limited in their ability to provide an early and accurate diagnosis of cardiorenal syndrome. Novel biomarkers have the potential to assist in the diagnosis of cardiorenal syndrome and guide treatment by evaluating the relative roles of implicated pathophysiological pathways such as hemodynamic dysfunction, neurohormonal activation, endothelial dysfunction, inflammation and oxidative stress, and fibrosis. In this review, we assess the utility of biomarkers that correlate with kidney and cardiac (dys)function, inflammation/oxidative stress, fibrosis, and cell cycle arrest, as well as emerging novel biomarkers (thrombospondin-1/CD47, glycocalyx and interleukin-1β) that may provide prediction and prognostication of cardiorenal syndrome, and guide potential development of targeted therapeutics.

The Role of Matrix Proteins in Cardiac Pathology

The extracellular matrix (ECM) and ECM-regulatory proteins mediate structural and cell-cell interactions that are crucial for embryonic cardiac development and postnatal homeostasis, as well as organ remodeling and repair in response to injury. These proteins possess a broad functionality that is regulated by multiple structural domains and dependent on their ability to interact with extracellular substrates and/or cell surface receptors. Several different cell types (cardiomyocytes, fibroblasts, endothelial and inflammatory cells) within the myocardium elaborate ECM proteins, and their role in cardiovascular (patho)physiology has been increasingly recognized. This has stimulated robust research dissecting the ECM protein function in human health and disease and replicating the genetic proof-of-principle. This review summarizes recent developments regarding the contribution of ECM to cardiovascular disease. The clear importance of this heterogeneous group of proteins in attenuating maladaptive repair responses provides an impetus for further investigation into these proteins as potential pharmacological targets in cardiac diseases and beyond.

Thirsty? Choose Water! Encouraging Secondary School Students to choose water over sugary drinks. A descriptive analysis of intervention components

BACKGROUND

Childhood obesity is a significant public health issue. Sugar-sweetened beverage (SSB) consumption contributes to this and adolescents are high consumers. This paper provides a descriptive overview of a school-based intervention to address this.

METHODS

61 secondary schools in New South Wales were randomised to receive a behavioural intervention (BI), a chilled water station (CWS), both interventions or neither (control). The BI was delivered through classroom lessons, school-based promotion and vaccination clinic. The CWS intervention included the installation of one CWS per school. Intervention effectiveness over time was assessed via student surveys at baseline, post-intervention and follow-up (individual-level outcomes), feedback from teachers and vaccination nurses, a school information survey, and remotely monitored CWS water usage (school-level outcomes).

RESULTS

Teachers reported the BI was useful in teaching students about drinking water and negative consequences of SSBs. Nurses considered the post-vaccination waiting period a good opportunity to deliver health promotion messages. Students in this group showed statistically significant changes in knowledge about SSBs, dehydration effects and changes in daily SSB consumption (T1 23.18%; T3 18.20%). Positive feedback regarding CWSs was received with an increase in water consumption reported for students in this group (T1 86.15% to T3 89.66%) and a statistically significant increase in students carrying a water bottle to school and filling it observed.

CONCLUSIONS

Both interventions were readily implemented with high levels of acceptability and impact on students' knowledge and SSB consumption. The study demonstrates how to promote water consumption in schools utilising two different interventions. SO WHAT?: Evidence regarding how to decrease SSB consumption amongst secondary school students has been strengthened.

Suppression and resolution of autoimmune arthritis by rhesus θ-defensin-1, an immunomodulatory macrocyclic peptide

θ-defensins constitute a family of macrocyclic peptides expressed exclusively in Old World monkeys. The peptides are pleiotropic effectors of innate immunity, possessing broad spectrum antimicrobial activities and immunoregulatory properties. Here we report that rhesus θ-defensin 1 (RTD-1) is highly effective in arresting and reversing joint disease in a rodent model of rheumatoid arthritis (RA). Parenteral RTD-1 treatment of DA/OlaHsd rats with established pristane-induced arthritis (PIA) rapidly suppressed joint disease progression, restored limb mobility, and preserved normal joint architecture. RTD-1 significantly reduced joint IL-1β levels compared with controls. RTD-1 dose-dependently inhibited fibroblast-like synoviocyte (FLS) invasiveness and FLS IL-6 production. Consistent with the inhibition of FLS invasiveness, RTD-1 was a potent inhibitor of arthritogenic proteases including ADAMs 17 and 10 which activate TNFα, and inhibited matrix metalloproteases, and cathepsin K. RTD-1 was non-toxic, non-immunogenic, and effective when administered as infrequently as once every five days. Thus θ-defensins, which are absent in humans, have potential as retroevolutionary biologics for the treatment of RA.

AxGxE: Using Flies to Interrogate the Complex Etiology of Neurodegenerative Disease

Progressive and late-onset neurological disorders such as Parkinson's disease and Alzheimer's disease affect up to 50 million people globally-a number postulated to double every 20 years in a continually aging population. While predisposing allelic variants in several genes clearly confer risk, individual age and specific environmental influences are equally important discriminators of disease onset age and progression. However, none of these factors can independently predict disease with significant precision. Therefore, we must actively develop models that accommodate contributions from all factors, potentially resulting in an A × G × E (age-gene-environment) metric that reflects individual cumulative risk and reliably forecasts disease outcomes. This effort can only be enabled by a deep quantitative understanding of the contribution of these factors to neurodegenerative disease, both individually and in combination. This is also an important consideration because neuronal loss typically precedes clinical presentation and disease-modifying therapies are contingent on early diagnosis that is likely to be informed by an accurate estimation of individual risk. Although epidemiological studies continue to make strong advances in these areas with the advent of powerful "omics"-based approaches, systematic phenotypic modeling of AxGxE interactions is currently more feasible in model organisms such as Drosophila melanogaster where all three parameters can be manipulated with manageable experimental burden. Here, we outline the advantages of using fruit flies for investigating these complex interactions and highlight potential approaches that might help synthesize existing information from diverse fields into a cogent description of age-dependent, environmental, and genetic risk factors in the pathophysiology of neurological disorders.

Rhesus macaque theta defensins suppress inflammatory cytokines and enhance survival in mouse models of bacteremic sepsis

Theta-defensins (θ-defensins) are macrocyclic antimicrobial peptides expressed in leukocytes of Old World monkeys. The peptides are broad spectrum microbicides in vitro and numerous θ-defensin isoforms have been identified in granulocytes of rhesus macaques and Olive baboons. Several mammalian α- and β-defensins, genetically related to θ-defensins, have proinflammatory and immune-activating properties that bridge innate and acquired immunity. In the current study we analyzed the immunoregulatory properties of rhesus θ-defensins 1–5 (RTDs 1–5). RTD-1, the most abundant θ-defensin in macaques, reduced the levels of TNF, IL-1α, IL-1β, IL-6, and IL-8 secreted by blood leukocytes stimulated by several TLR agonists. RTDs 1–5 suppressed levels of soluble TNF released by bacteria- or LPS-stimulated blood leukocytes and THP-1 monocytes. Despite their highly conserved conformation and amino acid sequences, the anti-TNF activities of RTDs 1–5 varied by as much as 10-fold. Systemically administered RTD-1 was non-toxic for BALB/c mice, and escalating intravenous doses were well tolerated and non-immunogenic in adult chimpanzees. The peptide was highly stable in serum and plasma. Single dose administration of RTD-1 at 5 mg/kg significantly improved survival of BALB/c mice with E. coli peritonitis and cecal ligation-and-puncture induced polymicrobial sepsis. Peptide treatment reduced serum levels of several inflammatory cytokines/chemokines in bacteremic animals. Collectively, these results indicate that the anti-inflammatory properties of θ-defensins in vitro and in vivo are mediated by the suppression of numerous proinflammatory cytokines and blockade of TNF release may be a primary effect.

Quantification of damage to suspended insect cells as a result of bubble rupture

It is proposed that when cells are either attached to, or very near, a rupturing bubble, the hydrodynamic forces associated with the rupture are sufficient to kill the cells. Four types of experiments were conducted to quantify the number and location of these killed cells. We determined: (1) the number of cells killed as a result of a single, 3.5-mm bubble rupture; (2) the number and viability of cells in the upward jet that results when a bubble ruptures; (3) the number of cells on the bubble film; and (4) the fate of cells attached to the bubble film after film rupture. All experiments were conducted with Spodoptera frugiperda (SF-9) insect cells, in TNM-FH and SFML medium, with and without Pluronic F-68. Experiments indicate that approximately 1050 cells are killed per single, 3.5-mm bubble rupture in TNM-FH medium and approximately the same number of dead cells are present in the upward jet. It was also observed that the concentration of cells in this upward jet is higher than the cell suspension in TNM-FH medium without Pluronic F-68 by a factor of two. It is believed that this higher concentration is the result of cells adhering to the bubble interface. These cells are swept up into the upward jet during the bubble rupture process. Finally, it is suggested that a thin layer around the bubble containing these absorbed cells is the "hypothetical killing volume" presented by other researchers. (c) 1994 John Wiley & Sons, Inc.

Medicinal and injection therapies for mechanical neck disorders

BACKGROUND

Controversy persists regarding medicinal therapies and injections.

OBJECTIVES

To determine the effects of medication and injections on primary outcomes (e.g. pain) for adults with mechanical neck disorders and whiplash.

SEARCH STRATEGY

We searched CENTRAL, MANTIS, CINAHL from their start to May 2006; MEDLINE and EMBASE to December 2006. We scrutinised reference lists for other trials.

SELECTION CRITERIA

We included randomised controlled trials with adults with neck disorders, with or without associated headache or radicular findings. We considered medicinal and injection therapies, regardless of route of administration.

DATA COLLECTION AND ANALYSIS

Two authors independently selected articles, abstracted data and assessed methodological quality. When clinical heterogeneity was absent, we combined studies using random-effects models.

MAIN RESULTS

We found 36 trials that examined the effects of oral NSAIDs, psychotropic agents, steroid injections, and anaesthetic agents. Trials had a mean of 3.1 on the Jadad Scale for methodological quality; 70% were high quality. For acute whiplash, administering intravenous methylprednisolone within eight hours of injury reduced pain at one week (SMD -0.90, 95% CI -1.57 to -0.24), and sick leave but not pain at six months compared to placebo in one trial. For chronic neck disorders at short-term follow-up, intramuscular injection of lidocaine was superior to placebo (SMD -1.36, 95% CI -1.93 to -0.80); NNT 3, treatment advantage 45% and dry needling, but similar to ultrasound in one trial each. In chronic neck disorders with radicular findings, epidural methylprednisolone and lidocaine reduced neck pain and improved function more than when given by intramuscular route at one-year follow-up, in one trial. In subacute and chronic neck disorders, muscle relaxants, analgesics and NSAIDs had limited evidence and unclear benefits. In participants with chronic neck disorders with or without radicular findings or headache, there was moderate evidence from five high quality trials that Botulinum toxin A intramuscular injections had similar effects to saline in improving pain (pooled SMD: -0.39, 95%CI -1.25 to 0.47), disability or global perceived effect.

AUTHORS' CONCLUSIONS

The major limitations are the lack of replication of the findings and sufficiently large trials. There is moderate evidence for the benefit of intravenous methylprednisolone given within eight hours of acute whiplash, from a single trial. Lidocaine injection into myofascial trigger points appears effective in two trials. There is moderate evidence that Botulinum toxin A is not superior to saline injection for chronic MND. Muscle relaxants, analgesics and NSAIDs had limited evidence and unclear benefits.

Medicinal and injection therapies for mechanical neck disorders

BACKGROUND

Medicinal therapies and injections are commonly recommended for neck pain, yet controversy persists over their effectiveness.

OBJECTIVES

To determine the effect of medicines and injections on pain, function/disability, patient satisfaction and range of motion in participants with mechanical neck disorders (MND).

SEARCH STRATEGY

We searched CENTRAL (Issue 4, 2002), and MEDLINE, EMBASE, MANTIS, CINHAL from their start to March 2003. We scrutinized reference lists for other trials.

SELECTION CRITERIA

We included randomized controlled trials with adults with MND, with or without associated headache or radicular findings. We considered medicinal and injection therapies, regardless of route of administration.

DATA COLLECTION AND ANALYSIS

Two authors independently selected articles, abstracted data and assessed methodological quality using the Jadad criteria. Consensus was used to resolve disagreements. When clinical heterogeneity was absent, we combined studies using random-effects meta-analysis models.

MAIN RESULTS

We found 32 trials that examined the effects of oral NSAIDs, psychotropic agents, injections of steroids, and anaesthetic agents. Overall, methodological quality had a mean of 3.2/5 on the Jadad Scale. For acute whiplash, administering intravenous methylprednisolone within eight hours reduced pain at one week, and sick leave but not pain at six months compared to placebo. For chronic MND at short-term follow-up, intramuscular injection of lidocaine was superior to placebo or dry needling, but similar to ultrasound. In chronic MND with radicular findings, epidural methylprednisolone and lidocaine reduced neck pain and improved function at one-year follow-up compared to the intramuscular route. In subacute/chronic MND, we found conflicting evidence of pain reduction for oral psychotropic agents compared to placebo or control. Single trials of eperison hydrochloride and tetrazepam showed positive results. Results for cyclobenzaprine were mixed. Diazepam did not show benefit. Other treatments including NSAIDS and nerve blocks had unclear or limited evidence of benefit. In participants with chronic MND with or without radicular findings or headache, there was moderate evidence from five high quality trials showing that Botox A intramuscular injections were not better than saline in improving pain (pooled SMD: -0.39 (95%CI: -1.25 to 0.47), disability or global perceived effect.

AUTHORS' CONCLUSIONS

Intra-muscular injection of lidocaine for chronic MND and intravenous injection of methylprednisolone for acute whiplash were effective treatments. There was limited evidence of effectiveness of epidural injection of methylprednisolone and lidocaine for chronic MND with radicular findings. Oral psychotropic agents had mixed results. There was moderate evidence that Botox A intramuscular injections for chronic MND were no better than saline. Other medications, including NSAIDs, had contradictory or limited evidence of effectiveness.

Adenylyl cyclase 3 mediates prostaglandin E(2)-induced growth inhibition in arterial smooth muscle cells

Arterial smooth muscle cell (SMC) proliferation contributes to a number of vascular pathologies. Prostaglandin E(2) (PGE(2)), produced by the endothelium and by SMCs themselves, acts as a potent SMC growth inhibitor. The growth-inhibitory effects of PGE(2) are mediated through activation of G-protein-coupled membrane receptors, activation of adenylyl cyclases (ACs), formation of cAMP, and subsequent inhibition of mitogenic signal transduction pathways in SMCs. Of the 10 different mammalian AC isoforms known today, seven isoforms (AC2-7 and AC9) are expressed in SMCs from various species. We show that, despite the presence of several different AC isoforms, the principal AC isoform activated by PGE(2) in human arterial SMCs is a calmodulin kinase II-inhibited AC with characteristics similar to those of AC3. AC3 is expressed in isolated human arterial SMCs and in intact aorta. We further show that arterial SMCs isolated from AC3-deficient mice are resistant to PGE(2)-induced growth inhibition. In summary, AC3 is the principal AC isoform activated by PGE(2) in arterial SMCs, and AC3 mediates the growth-inhibitory effects of PGE(2). Because AC3 activity is inhibited by intracellular calcium through calmodulin kinase II, AC3 may serve as an important integrator of growth-inhibitory signals that stimulate cAMP formation and growth factors that increase intracellular calcium.

SRF-dependent gene expression is required for PI3-kinase-regulated cell proliferation

Recent evidence indicates that phosphatidylinositol 3-kinase (PI3K) is a central regulator of mitosis, apoptosis and oncogenesis. Nevertheless, the mechanisms by which PI3K regulates proliferation are not well characterized. Mitogens stimulate entry into the cell cycle by inducing the expression of immediate early genes (IEGs) that in turn trigger the expression of G(1) cyclins. Here we describe a novel PI3K- regulated transcriptional cascade that is critical for mitogen regulation of the IEG, c-fos. We show that PI3K activates gene expression by transactivating SRF-dependent transcription independently of the previously described Rho and ETS TCF pathways. PI3K-stimulated cell cycle progression requires transactivation of SRF and expression of dominant- negative PI3K blocks mitogen-stimulated cell cycle progression. Furthermore, dominant-interfering SRF mutants attenuate mitogen-stimulated cell cycle progression, but are without effect on MEK-stimulated cell cycle entry. Moreover, expression of constitutively active SRF is sufficient for cell cycle entry. Thus, we delineate a novel SRF-dependent mitogenic cascade that is critical for PI3K- and growth factor-mediated cell cycle progression.

Disruption of the type III adenylyl cyclase gene leads to peripheral and behavioral anosmia in transgenic mice

Cyclic nucleotide-gated ion channels in olfactory sensory neurons (OSNs) are hypothesized to play a critical role in olfaction. However, it has not been demonstrated that the cAMP signaling is required for olfactory-based behavioral responses, and the contributions of specific adenylyl cyclases to olfaction have not been defined. Here, we report the presence of adenylyl cyclases 2, 3, and 4 in olfactory cilia. To evaluate the role of AC3 in olfactory responses, we disrupted the gene for AC3 in mice. Interestingly, electroolfactogram (EOG) responses stimulated by either cAMP- or inositol 1,4,5-triphosphate- (IP3-) inducing odorants were completely ablated in AC3 mutants, despite the presence of AC2 and AC4 in olfactory cilia. Furthermore, AC3 mutants failed several olfaction-based behavioral tests, indicating that AC3 and cAMP signaling are critical for olfactory-dependent behavior.

Ploidy Analysis and Ki-67 Expression in Myelodysplastic Syndromes

BACKGROUND

The Myelodysplastic Syndromes (MDS) are disorders involving clonal proliferative activity in the bone marrow that can lead to marrow failure and acute leukemia. This study was undertaken to evaluate the relationships between clinical factors, type of MDS, DNA ploidy, and Ki-67 expression.

DESIGN

Air-dried bone marrow smears from 27 patients were Feulgen stained for DNA and analyzed using the CAS 200 image analyzer. Ki-67 expression was also examined by image analysis in 25 of these cases in bone marrow core biopsy specimens using the monoclonal antibody MIB-1. Age, sex, bone marrow cellularity, and MDS grade of each patient were also recorded. Percent S-phase was assessed only for the diploid samples.

RESULTS

There were 16 diploid and 11 aneuploid cases on analysis of Feulgen-stained bone marrow aspirate smears. The percentage of MIB-1+ cells ranged from 6.4%-61.7% (mean-37.7 ± 6.4%). Among the 16 diploid cases, 18.2 ± 5.7% of the cells were in S-phase. High grade MDS (RAEB-T, RAEB, CMML) was associated with younger age and male sex (p = 0.03), lower percentage of cells in S-phase (p = 0.04), greater bone marrow cellularity (p = 0.005), and greater MIB-1 expression (p = 0.04). With increasing age, there were more females (p = 0.03), more low grade MDS (RA, RARS), and a lower percentage of cells in S-Phase (p = 0.04). Female patients tended to be older, have less cellular bone marrows (p = 0.003), less MIB-1 expression (p = 0.03), low grade MDS (p = 0.02), and increased percentage of cells in S phase (p = 0.008).

CONCLUSION

Ki-67 expression, percent cells in S-phase, clinical parameters and subtype of MDS tend to distinguish two separate groups of MDS patients, and may explain in part the difference in biologic behaviour between high and low grade MDS.

Metabolic impact of adenovirus-mediated overexpression of the glucose-6-phosphatase catalytic subunit in hepatocytes

Glucose-6-phosphatase (G6Pase) catalyzes the hydrolysis of glucose 6-phosphate (Glu-6-P) to free glucose and, as the last step in gluconeogenesis and glycogenolysis in liver, is thought to play an important role in glucose homeostasis. G6Pase activity appears to be conferred by a set of proteins localized to the endoplasmic reticulum, including a glucose-6-phosphate translocase, a G6Pase phosphohydrolase or catalytic subunit, and glucose and inorganic phosphate transporters in the endoplasmic reticulum membrane. In the current study, we used a recombinant adenovirus containing the cDNA encoding the G6Pase catalytic subunit (AdCMV-G6Pase) to evaluate the metabolic impact of overexpression of the enzyme in primary hepatocytes. We found that AdCMV-G6Pase-treated liver cells contain significantly less glycogen and Glu-6-P, but unchanged UDP-glucose levels, relative to control cells. Further, the glycogen synthase activity state was closely correlated with Glu-6-P levels over a wide range of glucose concentrations in both G6Pase-overexpressing and control cells. The reduction in glycogen synthesis in AdCMV-G6Pase-treated hepatocytes is therefore not a function of decreased substrate availability but rather occurs because of the regulatory effects of Glu-6-P on glycogen synthase activity. We also found that AdCMV-G6Pase-treated-cells had significantly lower rates of lactate production and [3-3H]glucose usage, coupled with enhanced rates of gluconeogenesis and Glu-6-P hydrolysis. We conclude that overexpression of the G6Pase catalytic subunit alone is sufficient to activate flux through the G6Pase system in liver cells. Further, hepatocytes treated with AdCMV-G6Pase exhibit a metabolic profile resembling that of liver cells from patients or animals with non-insulin-dependent diabetes mellitus, suggesting that dysregulation of the catalytic subunit of G6Pase could contribute to the etiology of the disease.

Adenovirus-mediated expression of the catalytic subunit of glucose-6-phosphatase in INS-1 cells. Effects on glucose cycling, glucose usage, and insulin secretion

Glucose-6-phosphatase (Glu-6-Pase) catalyzes the terminal step of gluconeogenesis, the conversion of glucose 6-phosphate (Glu-6-P) to free glucose. This enzyme activity is thought to be conferred by a complex of proteins residing in the endoplasmic reticulum (ER), including a Glu-6-P translocase that transports Glu-6-P into the lumen of the ER, a phosphohydrolase catalytic subunit residing in the lumen, and putative glucose and inorganic phosphate transporters that allow exit of the products of the reaction. In this study, we have investigated the effect of adenovirus-mediated overexpression of the Glu-6-Pase catalytic subunit on glucose metabolism and insulin secretion, using a well differentiated insulinoma cell line, INS-1. We found that the overexpressed Glu-6-Pase catalytic subunit was normally glycosylated, correctly sorted to the ER, and caused a 10-fold increase in Glu-6-Pase enzymatic activity in in vitro assays. Consistent with these findings, a 4.2-fold increase in 3H2O incorporation into glucose was observed in INS-1 cells treated with the recombinant adenovirus containing the Glu-6-Pase catalytic subunit cDNA (AdCMV-Glu-6-Pase). 3-[3H]Glucose usage was decreased by 32% in AdCMV-Glu-6-Pase-treated cells relative to controls, resulting in a proportional 30% decrease in glucose-stimulated insulin secretion. Our findings indicate that overexpression of the Glu-6-Pase catalytic subunit significantly impacts glucose metabolism and insulin secretion in islet beta-cells. However, INS-1 cells treated with AdCMV-Glu-6-Pase do not exhibit the severe alterations of beta-cell function and metabolism associated with islets from rodent models of obesity and non-insulin-dependent diabetes mellitus, suggesting the involvement of genes in addition to the catalytic subunit of Glu-6-Pase in the etiology of such beta-cell dysfunction.

Isolation and sequence of a novel human chondrocyte protein related to mammalian members of the chitinase protein family

We describe the isolation of a novel protein from the conditioned medium of human articular cartilage chondrocytes in primary culture. This 39-kDa protein has the N-terminal sequence YKL, which we have termed YKL-39. The 1434-nucleotide sequence of the YKL-39 cDNA predicts a 385-residue initial translation product and a 364-residue mature YKL-39. The amino acid sequence of YKL-39 is most closely related to YKL-40, followed by macrophage chitotriosidase, oviductal glycoprotein, and macrophage YM-1. All five proteins share significant sequence identity with bacterial chitinases and have the probable structure of an (alphabeta)8 barrel. YKL-39 lacks the active site glutamate, which is essential for the activity of chitinases, and as expected has no chitinase activity. The highest level of YKL-39 mRNA expression is seen in chondrocytes, followed by synoviocytes, lung, and heart. YKL-39 accounts for 4% of the protein in chondrocyte-conditioned medium, prostromelysin accounts for 17%, and YKL-40 accounts for 33%. In contrast to YKL-40, YKL-39 is not a glycoprotein and does not bind to heparin.