Repurposing glycated hemoglobin as a possible marker of myocardial ageing in asymptomatic older adults

Background

The adverse consequences of diabetes mellitus on cardiovascular health is well-established. However, few studies have studied the impact of diabetes on ageing. In our previous investigations, we identified distinct patterns of myocardial ageing among older adults otherwise asymptomatic for clinical cardiovascular disease. In this analysis, we hypothesize that glycated hemoglobin (HbA1c) may be differentially associated with these distinct signatures of myocardial ageing, thereby providing greater precision towards future preventative trials.

Methods

We performed extensive cardiovascular examinations on a cohort of asymptomatic aged community adults. Transthoracic echocardiography measured left ventricular structure and function. LV filling pressure was measured as the ratio between early mitral inflow velocity and mitral annular early diastolic velocity. Longitudinal left atrial (LA) strain comprising reservoir strain (ɛs), conduit strain (ɛe) and booster strain (ɛa) and their corresponding peak strain rates (SRs, SRe, SRa) were measured using cardiac magnetic resonance (CMR) feature tracking technique. Blood sampling for biomarkers were performed simultaneously with cardiovascular examinations.

Results

Among n=515 community adults in sinus rhythm and without cardiovascular disease [mean age 73±4 years, 255 (50%) females], 116 (23%) had diabetes. Age (73 vs 73 years) and heart rate (72 vs 75 beats per minute) were similar between diabetic and non-diabetic older adults. Diabetic older adults are mostly male (59% vs 48%, p=0.046), had larger body mass indices (24 vs 23 kg/m2, p=0.027), and greater burdens of hypertension (81% vs 41%, p<0.0001) and dyslipidemia (79% vs 43%, p<0.0001), compared to non-diabetic older adults. Diabetics had worse LV myocardial relaxation [(ratio of peak velocity flow in early diastole E (m/s) to peak velocity flow in late diastole by atrial contraction A (m/s), 0.8±0.2 vs 0.9±0.3, p=0.031), worse LV filling pressures (10.9±3.1 vs 10.1±3.3, p=0.022), reductions in LA global strain (−33±17 vs −28±9.7, p=0.016), LA conduit strain ɛe (12±4.3 vs 14±4.1, p=0.045), increases in SRe (−1.2±0.4 vs −1.3±0.5, p=0.042) and reductions in SRe: SRa ratio (0.5±0.2 vs 0.7±0.3, p=0.0059) compared to non-diabetics. Based on multivariate analysis, HbA1c was independently associated with LV myocardial relaxation (β=−0.08 (−0.1, −0.03), p=0.002), LA conduit strain (β=−0.9, (−1.6, −0.1), p=0.025), LA conduit strain rate (β=0.1, (0.04, 0.2), p=0.005), strongly associated with LA global strain (β=3.0, (0.9, 5.1), p=0.006), but not associated with LV filling pressure (β=0.5 (−0.04, 1.0), p=NS).

Conclusion

Our detailed examinations revealed distinct associations between glycated hemoglobin and myocardial functions that additionally varied in magnitude. As a contemporary biomarker, glycated hemoglobin may be useful for stratifying risks associated with myocardial ageing, particularly in ageing-related left atrial myopathies.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): National Medical Research Council of Singapore; Singhealth Foundation

The Application of Non-linear Flow Resistance in Cerebral Artery: Compared with Windkessel Model based on Genetic Algorithm

Continuous blood pressure is measured from various extracranial body sites, with difference in amplitude and phase with intracranial blood pressure. Consequent influences on the accuracy of Windkessel model need further investigation. Between blood pressure and intracranial flow rate, a model with non-linear flow resistance (R-DT) was proposed and compared with the 3-element Windkessel (RCR) model. From the measured blood flow velocity in middle cerebral artery, the blood pressure was estimated by R-DT and RCR models respectively. The parameters in the models were optimized by genetic algorithm. The accuracies of R-DT and RCR models were compared based on their estimation errors to the measured blood pressure. The capacitance element in RCR model indicated limited ability to take the time shift into account. Compared with RCR model, R-DT model had less error (averaged relative error: 5.19% and 2.49% for RCR and RDT models). The non-linear flow resistance was applicable in simulating cerebral arteries.

A functional macrophage migration inhibitory factor promoter polymorphism is associated with reduced diffusing capacity

Cigarette smoke exposure is the leading modifiable risk factor for chronic obstructive pulmonary disease (COPD); however, the clinical and pathologic consequences of chronic cigarette smoke exposure are variable among smokers. Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine implicated in the pathogenesis of COPD. Within the promoter of the MIF gene is a functional polymorphism that regulates MIF expression (-794 CATT_5-8 microsatellite repeat) ( rs5844572 ). The role of this polymorphim in mediating disease susceptibility to COPD-related traits remains unknown. We performed a cross-sectional analysis of DNA samples from 641 subjects to analyze MIF-794 CATT_5-8 ( rs5844572 ) polymorphism by standard methods. We generated multivariable logistic regression models to determine the risk of low expressing MIF alleles for airflow obstruction [defined by forced expiratory volume in 1 s (FEV₁)/forced vital capacity ratio <0.70] and an abnormal diffusion capacity [defined by a diffusion capacity for carbon monoxide (DL_CO) percent predicted <80%]. We then used generalized linear models to determine the association of MIF genotypes with FEV₁ percent predicted and DL_CO percent predicted. The MIF-794 CATT₅ allele was associated with an abnormal diffusion capacity in two cohorts [odds ratio (OR): 9.31, 95% confidence interval (CI): 1.97-4.06; and OR: 2.21, 95% CI: 1.03-4.75]. Similarly, the MIF-794 CATT₅ allele was associated with a reduced DL_CO percentage predicted in these two cohorts: 63.5 vs. 70.0 ( P = 0.0023) and 60.1 vs. 65.4 ( P = 0.059). This study suggests an association between a common genetic polymorphism of an endogenous innate immune gene, MIF, with reduced DL_CO, an important measurement of COPD severity.

Comparative transcriptome profiles of Lindian chicken eyelids identify melanin genes controlling eyelid pigmentation

1. During the long history of chicken domestication, eyelid colour, like skin colour and shank colour, has been one of the physical traits of Chinese indigenous chickens that influence consumer buying behaviour. In China, the Lindian chicken, which has coloured feathers, is renowned for the appetizing flavour of its meat and eggs, and its eyelid colours vary from deep (black) to light shades (light yellow). 2. To investigate genes involved in eyelid colour, the expression profiles of black and light-yellow eyelids of Lindian chickens were analysed with transcriptome sequencing. 3. A total of 13 466 genes were detected in the eyelids, among which 14 were differentially expressed. Among these differentially expressed genes (DEGs), three key genes, premelanosome protein (PMEL), dopachrome tautomerase (DCT), and tyrosinase (TYR), encoded proteins that positively regulate melanogenesis and melanin deposition. PMEL, DCT and TYR were expressed much more strongly in the black eyelids than in the light-yellow eyelids. A Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that tyrosine metabolism and melanogenesis genes were significantly enriched among these DEGs (corrected P < 0.05). 4. In conclusion, melanin may be one of the main factors involved in Lindian chicken eyelid colour. Furthermore, these results provide a valuable resource for the future study of the physical traits of Lindian chicken.

800Gb/s (8x128Gb/s) unrepeatered transmission over 515-km large-area ultra-low-loss fiber using 2nd-order Raman pumping

We demonstrate unrepeatered transmission of 8x128Gb/s PDM-QPSK signals over a 515k-m fiber link. This ultra-long distance of 800 Gb/s unrepeatered transmission in a single fiber configuration is achieved by employing enabling techniques such as large-effective-area ultra-low-attenuation fibers, co-propagating and counter-propagating 2nd-order-pumped distributed Raman amplification, and remote optically pumped amplifier (ROPA). The ROPA itself is also counter-propagating 2nd-order Raman pumped. The designs and characteristics of the ROPA and 2nd-order pumped distributed Raman amplification are described, and optimization of the transmission performance of this ultra-long reach 800Gb/s unrepeatered transmission fiber link is discussed in this paper.

Comparison of serum biochemical parameters between two broiler chicken lines divergently selected for abdominal fat content

In humans, obesity is associated with increased or decreased levels of serum biochemical indicators. However, the relationship is not as well understood in chickens. Due to long-term intense selection for fast growth rate, modern broilers have the problem of excessive fat deposition, exhibiting biochemical or metabolic changes. In the current study, the Northeast Agricultural University broiler lines divergently selected for abdominal fat content (NEAUHLF) were used to identify differences in serum biochemical parameters between the 2 lines. A total of 18 serum biochemical indicators were investigated in the 16th, 17th, and 18th generation populations of NEAUHLF, and the genetic parameters of these serum biochemical indicators were estimated. After analyzing the data from these 3 generations together, the results showed that the levels of 16 of the tested serum biochemical parameters were significantly different between the lean and fat birds. In the fat birds, serum concentrations of high-density lipoprotein cholesterol (HDL-C), HDL-C:low-density lipoprotein cholesterol (LDL-C), total bile acid, total protein, albumin, globulin, aspartate transaminase (AST):alanine transaminase (ALT), γ-glutamyl transpeptidase (GGT), uric acid, and creatinine were very significantly higher (P < 0.01), whereas LDL-C, albumin:globulin, glucose, AST, ALT, and free fatty acids concentrations in serum were very significantly lower than those in the lean birds (P < 0.01). Of these 16 serum biochemical parameters, 5 (LDL-C, HDL-C:LDL-C, total bile acid, albumin, and albumin:globulin) had high heritabilities (0.58 ≤ h2 ≤ 0.89), 6 (HDL-C, total protein, globulin, AST:ALT, GGT, and creatinine) had moderate heritabilities (0.29 ≤ h2 ≤ 0.48), and the remaining 5 had low heritabilities (h2 < 0.20). Serum HDL-C, HDL-C:LDL-C, and glucose had higher positive genetic correlation coefficients (rg) with abdominal fat traits (0.30 ≤ rg ≤ 0.80), whereas serum globulin, AST, and uric acid showed higher negative genetic correlations with abdominal fat traits (–0.62 ≤ rg ≤ –0.30). The remaining 10 serum biochemical parameters had lower genetic correlations with abdominal fat traits (–0.30 < rg < 0.30). In conclusion, we identified serum HDL-C and HDL-C:LDL-C levels as potential biomarkers for selection of lean birds. These findings will also be useful in future studies for investigating obesity and lipid metabolism in humans as well as in other animal species.

Expression analysis of bone morphogenetic protein 4 between fat and lean birds in adipose tissue and serum

The objectives of the present study were to characterize the tissue expression of chicken (Gallus gallus) bone morphogenetic protein 4 (BMP4) and compare differences in its expression in abdominal fat tissue and serum between fat and lean birds and to determine a potential relationship between the expression of BMP4 and abdominal fat tissue growth and development. The results showed that chicken BMP4 messenger RNA (mRNA) and protein were expressed in various tissues, and the expression levels of BMP4 transcript and protein were relatively higher in adipose tissues. In addition, the mRNA and protein expression levels of BMP4 in abdominal fat tissue of fat males were lower than those of lean males at 1, 2, 5, and 7 wk of age (P < 0.05). Furthermore, the serum BMP4 content of fat males was lower than that of lean males at 7 wk of age (P < 0.05). BMP4 mRNA expression levels were significantly higher in preadipocytes than those in mature adipocytes (P < 0.05), and the expression level decreased during differentiation in vitro (P < 0.05). These results suggested that chicken BMP4 might affect abdominal fat deposition through differences in its expression level. The results of this study will provide basic molecular information for studying the role of BMP4 in the regulation of adipogenesis in avian species.

Macrophage migration inhibitory factor promotes eosinophil accumulation and tissue remodeling in eosinophilic esophagitis

Macrophage migration inhibitory factor (MIF) is involved in eosinophil biology and in type 2 inflammation, contributing to allergic and helminthic diseases. We hypothesized that MIF participates in the pathogenesis of eosinophilic esophagitis (EoE), an allergic condition characterized by esophageal eosinophilic inflammation. MIF is highly expressed in esophageal mucosa of patients with EoE, compared with gastro-esophageal reflux disease and control patients, where it co-localizes predominantly with eosinophils. In vitro, recombinant MIF promotes human eosinophil chemotaxis, while MIF antagonist and CXCR4 antagonist, AMD3100, revert this effect. In a model of EoE induced by ovalbumin, Mif-deficient mice have reduced inflammation and collagen deposition compared with wild-type (WT) mice. Importantly, treatment of WT mice with anti-MIF or with AMD3100 during the challenge phase prevents accumulation of eosinophils and tissue remodeling. Conversely, recombinant MIF promoted tissue eosinophil inflammation in allergic mice. Together, these results implicate MIF in the pathogenesis of esophageal inflammation and suggest that targeting MIF might represent a novel therapy for EoE.

Estimating the genetic parameters for liver fat traits in broiler lines divergently selected for abdominal fat

Intensive selection of broilers for improved growth rate is known to exert a negative effect on broiler health, such as an increase in body fat (and its related diseases). Excessive fat deposition in the liver can cause fatty liver hemorrhagic syndrome (FLHS); in addition, traits associated with liver fat have also been associated with FLHS. This study explored the genetic relationships among liver fat-related traits. Data was collected from 462 birds derived from 16th generation Northeast Agricultural University broiler lines divergently selected for abdominal fat content. The body weight at 7 weeks of age (BW7), abdominal fat weight (AFW), abdominal fat percentage, liver fat percentage (LFP), liver weight, and liver percentage were measured. The heritability of these traits and the phenotypic and genetic correlations were estimated, using the restricted maximum likelihood (REML) and Gibbs sampling (GS) methods. The REML and GS methods yielded similar heritability estimates for LFP (0.36 and 0.37, respectively). BW7 showed a high positive genetic correlation with AFW (rA(REML) = 0.74 and rA(GS) = 0.80), and a moderate positive genetic correlation with LFP (rA(REML) = 0.27 and rA(GS) = 0.39). Positive genetic correlations were also observed between AFW and LFP (rA(REML) = 0.35 and rA(GS) = 0.36). These results suggested that selection for growth may increase the AFW and LFP in broilers. LFP is directly related to FLHS; therefore, selection for broiler growth rate may increase the incidence of FLHS.

Microarray analysis of differentially expressed genes in the liver between Bai'er layers and broilers

In this study, we profiled gene expression in chicken liver and screened differentially expressed genes in the Bai'er layers and fat line broilers. Birds were derived from the 14th generation of Northeast Agricultural University fat broiler lines and Bai'er layers. Chicken genome arrays were used to screen differentially expressed genes in liver tissue from the Bai'er layers and fat line broilers. We screened 671 differentially expressed genes between broilers and layers at the ages of 2 and 4 weeks. We observed enrichment of a series of significant pathways, including the mitogen-activated protein kinase signaling pathway, cell cycle, mammalian target of rapamycin signaling pathway, and p53 signaling pathway. At 2 and 4 weeks, 94 shared differentially expressed genes were observed. We speculated that these genes regulate chicken lipid metabolism.

Differentially expressed genes in the liver of lean and fat chickens

This study aimed to investigate gene expression in the chicken liver for lean and fat broiler lines. Birds used in this study were 2 and 4 weeks of age; they were derived from the 14th generation of Northeast Agricultural University broiler lines, which were divergently selected based on abdominal fat content. Chicken Genome Arrays were used to screen differentially expressed genes in the liver tissue from lean and fat birds. At 2 and 4 weeks of age, 770 and 452 genes were differentially expressed between the 2 lines, respectively. The differentially expressed genes were involved in Wnt, insulin signaling, and cell cycle pathways. At 2 and 4 weeks, 42 shared, differentially expressed genes were revealed by the analysis. We speculate that these genes might regulate chicken lipid metabolism.

CD84 is a survival receptor for CLL cells

Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of CD5+ B lymphocytes in peripheral blood, lymphoid organs and bone marrow. The main feature of the disease is accumulation of the malignant cells due to decreased apoptosis. CD84 belongs to the signaling lymphocyte activating molecule family of immunoreceptors, and has an unknown function in CLL cells. Here, we show that the expression of CD84 is significantly elevated from the early stages of the disease, and is regulated by macrophage migration inhibitory factor and its receptor, CD74. Activation of cell surface CD84 initiates a signaling cascade that enhances CLL cell survival. Both downmodulation of CD84 expression and its immune-mediated blockade induce cell death in vitro and in vivo. In addition, analysis of samples derived from an on-going clinical trial, in which human subjects were treated with humanized anti-CD74 (milatuzumab), shows a decrease in CD84 messenger RNA and protein levels in milatuzumab-treated cells. This downregulation was correlated with reduction of Bcl-2 and Mcl-1 expression. Thus, our data show that overexpression of CD84 in CLL is an important survival mechanism that appears to be an early event in the pathogenesis of the disease. These findings suggest novel therapeutic strategies based on the blockade of this CD84-dependent survival pathway.

Distribution maps of D-dopachrome tautomerase in the mouse brain

D-Dopachrome tautomerase is an enzyme related by amino acid sequence and catalytic activity to macrophage migration inhibitory factor. Both of these small molecules are pro-inflammatory cytokines mediating broad innate immune responses. Although it is well established that the gene product of D-dopachrome tautomerase is widely expressed in liver and kidney cells, no study has mapped the distribution pattern of this tautomeric enzyme in the mammalian nervous system. Here, we address this void by characterizing the cellular localization of D-dopachrome tautomerase in the adult mouse brain. Two well-characterized polyclonal antibodies were used for Western blotting and immunohistochemical localization of the endogenous tautomeric enzyme. Our results show that D-dopachrome tautomerase is present throughout the brain parenchyma with a large fraction of heterogeneous interneurons harboring a stable and robust expression of the enzyme. These data point to a potential involvement of D-dopachrome tautomerase activity in the mature mouse brain, and suggest some functional and evolutionary relationship between innate immunity and tautomerization of D-dopachrome in mammalian species.

Elevated levels of macrophage migration inhibitory factor in women with metabolic syndrome

Metabolic syndrome is a complex clinical disorder characterized by obesity, a disturbance of glucose metabolism, dyslipidemia, and hypertension, leading to increased cardiovascular risk. Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine produced both by innate immune cells and by adipocytes, and it plays an important role in inflammatory and cardiovascular diseases. The goal of this study was to evaluate the expression of circulating MIF in patients with metabolic syndrome. A study was conducted involving 172 persons who attended the Jeju National University Hospital Health Promotion Center. Among the 172 subjects, 88 patients with metabolic syndrome and 84 healthy control subjects were included. Serum MIF levels were considerably higher in patients with metabolic syndrome than in healthy subjects (mean±SEM, 1413.0-pg/ml±102.6 vs. 1077.0-pg/ml±-91.3, p=0.016). Among the metabolic syndrome patients, MIF levels were significantly increased in women (1403.0-pg/ml±114.2 vs. 921.3 pg/ml±117.3, p=0.005), but not in men. Even after further linear regression adjustment for age and body mass index, the expression of MIF for women with metabolic syndrome was still clearly elevated when compared to healthy subjects (p=0.011). Circulating MIF concentrations showed a gender disparity between healthy and metabolic syndrome subjects. An elevation of systemic MIF in women with metabolic syndrome may contribute to pathogenesis of metabolic syndrome or to the development of metabolic syndrome-related diseases, such as atherosclerosis and type 2 diabetes mellitus.

Effects of excessive selenium supplementation to diet contaminated with deoxynivalenol on blood phagocytic activity and antioxidative status of broilers

This study examined the effects of excessive dietary supplementation with organic selenium on phagocytic activity and antioxidative status of chickens for fattening fed diet contaminated with deoxynivalenol (DON). Sixty chickens of Ross 308 hybrids were at day of hatching divided into four groups with 15 birds in each. The background DON dietary levels in both negative and positive control groups were 0.2 mg/kg. The complete feed for positive control group was supplemented with Se dose 1 mg/kg in the form of Se-yeast. Group 3 was fed diet with DON level 3 mg/kg while diet for group 4 combined DON level 3 mg/kg with a excessive supplement of Se-yeast (Se dose 1 mg/kg). After 6 weeks of dietary intake, six randomly-chosen chickens from each group were sampled. Feeding of contaminated diet resulted in significantly reduced blood phagocytic activity (19.5 ± 1.1% in the negative control vs. 12.8 ± 0.8% in the DON-treated group, p < 0.05). Se-yeast supplemented to the DON contaminated diet prevented suppression of phagocytic activity. Dietary intake of DON at levels 3 mg/kg did not influence the plasma α-tocopherol level while excessive dietary Se dose reduced it in both Se supplemented groups. Neither the birds of DON-treated group nor the birds from group 4 with DON and Se-yeast showed any response in plasma γ-glutamyltransferase (GGT) activity. Subtoxic dietary level of DON significantly increased the activity of glutathione peroxidase (GPx) in the duodenal mucosa, while additional Se supplementation prevented such a response to mycotoxin. On the other hand, both Se supplemented groups showed significantly elevated GPx activities in blood, liver and kidney, (p < 0.05). The results suggest a potential ability of excessive supplementation of organic selenium to prevent the blood phagocytic activity suppression and changes in GPx activity in duodenal tissue induced in broilers by subtoxic dietary levels of DON.

Tissue expression characterization of chicken adipocyte fatty acid-binding protein and its expression difference between fat and lean birds in abdominal fat tissue

Fatty acid-binding proteins are considered to be the carriers for the transportation of intracellular fatty acids and play an important role in the development of fatness traits. Adipocyte fatty acid-binding protein (A-FABP) is one of the family members. The current study was designed to analyze the tissue expression characterization of chicken A-FABP and its expression difference between the fat and lean males in abdominal fat tissue to reveal the possible relationship between the expression of A-FABP and abdominal fat tissue development and growth in chicken. First, fusion protein glutathione S-transferase/A-FABP was induced and purified, and then the antiserum containing specific polyclonal antibodies was obtained by immunizing healthy female rabbits using the purified fusion protein. Second, tissue expression characterization of A-FABP was investigated by Western blot. Finally, A-FABP expression difference in abdominal fat tissue between the fat and lean males was investigated by real-time reverse transcription-PCR and Western blot methods. The results showed that A-FABP expressed specifically in abdominal fat tissue and the mRNA expression level of A-FABP in fat males was lower than that of lean males at 2, 3, 4, 6, 7, 9, and 10 wk of age (P<0.05), and the protein expression level of fat males was lower than that of lean males at 6 and 10 wk of age (P<0.05). These results suggested that chicken A-FABP might affect abdominal fat deposition through changing its expression level, and the possible mechanism may be that a high expression level of A-FABP induced the high lipolytic rate and led to the decreased abdominal fat mass accordingly.

A polymorphism in the 3'-flanking region of insulin-like growth factor binding protein 2 gene associated with abdominal fat in chickens

Insulin-like growth factor binding protein 2 (IGFBP2) is the predominant insulin-like growth factor binding protein in serum of different species. It binds insulin-like growth factors and plays an important role in growth and fat metabolism. The current study was designed to investigate the associations of IGFBP2 gene 3'-flanking region polymorphisms with chicken fatness traits. The random populations (5 distinct populations: Arbor Acres broiler, Hyline Brown layer, Shiqiza, BeijingYou, and Baier), the Northeast Agricultural University broiler lines divergently selected for abdominal fat content (NEAUHLF), and the the Northeast Agricultural University F(2) (NEAU F(2)) resource population were used in the current study. Body weight and body composition traits were measured in NEAUHLF and NEAU F(2) populations. A SNP of 1196C > A in the 3'-flanking region of the IGFBP2 gene was detected, and the PCR-single strand conformation polymorphism method was then used to genotype all of the individuals derived from the above populations. There was a highly significant difference (P < 0.01) in the allele frequency among the 5 distinct populations. The IG-FBP2 polymorphism was significantly associated with abdominal fat weight and percentage of abdominal fat (P < 0.05) in NEAUHLF and NEAU F(2) populations. The research suggests that the IGFBP2 gene could be a candidate locus or linked to a major gene that affects fatness traits in chickens.

Stereo and enantioselective degradation of beta-Cypermethrin and beta-Cyfluthrin in soil

beta-Cypermethrin (beta-CP) and beta-Cyfluthrin (beta-CF) are two important pyrethroid insecticides and both consist of two enantiomeric pairs (diastereomers), i.e. four enantiomers. In this study, the stereo and enantioselective degradation of beta-CP and beta-CF in a Tianjin alkaline soil was studied in details by a combination of achiral and chiral HPLC. The results showed that for the two pyrethroids, the transdiastereomer was degraded faster than the corresponding cis-diastereomer. beta-CP and beta-CF were found to be configurationally unstable in this soil, since isomerization between diastereomers was observed during the degradation process. Further enantioselective analysis showed that significant enantioselectivity occurred during the 30 days incubation time. The enantiomeric ratio (ER) values of cis- and transdiastereomers changed from initial approximately 1.00 to final 0.79 and 0.55 for beta-CP, and to 0.64 and 0.48 for beta-CF, respectively. At last, it was found that beta-CF was degraded at relatively faster degradation rate and higher enantioselectivity than beta-CP. Findings from this study may be used to better understand the chiral profiles of beta-CP and beta-CF as well as relevant pyrethroid analogues in environment.

Macrophage migration inhibitory factor (MIF) gene polymorphisms are associated with increased prostate cancer incidence

Recurrent or persistent inflammation has emerged as an important factor in cancer development. Overexpression of macrophage migration inhibitory factor (MIF), an upstream regulator of innate immunity with pleiotropic effects on cell proliferation, has been implicated in prostate cancer (CaP). Two polymorphisms in the promoter of the MIF gene (-173G to C transition and seven copies of the -794 CATT repeat) are associated with increased MIF expression in vivo and poor prognosis in autoimmune diseases. We conducted a retrospective analysis of 131 CaP patients and 128 controls from a group of Veterans' Administration patients undergoing routine prostate-specific antigen screening. Patients with CaP were enrolled regardless of treatment. Inclusion criteria for the control group were absence of documented diagnosis of cancer and/or chronic inflammation within patient computerized records. Logistic regression demonstrated a significant association between CaP and the -173G/C, the -173C/C and the -794 7-CATT MIF polymorphisms (P<0.001). Patients with the -794 7-CATT allele had an increased risk of CaP recurrence at 5 years. Individuals with -173G/C, -173C/C and -794 7-CATT MIF genotypes have an increased incidence of CaP and these genotypes may serve as an independent marker for cancer recurrence.

Macrophage migration inhibitory factor (MIF) promotes cell survival by activation of the Akt pathway and role for CSN5/JAB1 in the control of autocrine MIF activity

The phosphoinositide-3-kinase (PI3K)/Akt signaling pathway plays an important role in cell survival and the development of cancer. Macrophage migration inhibitory factor (MIF) is a critical inflammatory cytokine that was recently associated with tumorigenesis and that potently inhibits apoptosis. This may involve inhibition of p53-dependent genes, but the initiating molecular mechanism of how MIF controls survival/apoptosis is unknown. Here, we show that MIF prevents apoptosis and promotes tumor cell survival by directly activating the Akt pathway. MIF enhanced Akt activity in primary and immortalized fibroblasts (MEF and NIH/3T3), HeLa cervix carcinoma cells and various breast cancer cell lines. Activation was abolished by kinase inhibitors Ly294002 and PP2 and in Src/Yes/Fyn(SYF)(-/-) and CD74(-/-)(MEFs), while being enhanced in CD74-overexpressing MEFs, demonstrating that the MIF-induced Akt pathway encompasses signaling through the MIF receptor CD74 and the upstream kinases Src and PI3K. Akt was activated by exogenous rMIF and autocrine MIF action, as revealed by experiments in MIF(-/-)MEFs and antibody blockade. siRNA knockdown of CSN5/JAB1, a tumor marker and MIF-binding protein, showed that JAB1 controls autocrine MIF-mediated Akt signaling by inhibition of MIF secretion. Akt activation by MIF led to phosphorylation of the proapoptotic proteins BAD and Foxo3a. Apoptosis inhibition by MIF was functionally associated with Akt activation as it was abolished by overexpression of the Akt pathway inhibitor PTEN and occurred independently of p53. This was shown by studying DNA damage-induced apoptosis in fibroblasts, the Fas death pathway in HeLa cells that do not express functional p53, and etoposide-induced apoptosis in breast carcinoma cells expressing mutant p53. Importantly, dependence of breast cancer cell survival on MIF correlated with Akt activation and the PTEN status of these cells. Thus, MIF can directly promote cell survival through activation of the PI3K/Akt pathway and this effect is critical for tumor cell survival.

Tissue expression and association with fatness traits of liver fatty acid-binding protein gene in chicken

Fatty acid-binding proteins belong to a superfamily of lipid-binding proteins that exhibit a high affinity for long-chain fatty acids and appear to function in metabolism and intracellular transportation of lipids. The current study was designed to investigate expression characterization and association with growth and composition traits of the liver fatty acid-binding protein (L-FABP) gene in the chicken. Northern blot analysis indicated that the gene, similar to the mammal L-FABP gene, was expressed only in liver and intestinal tissues. The mRNA levels of the chicken L-FABP gene in liver and intestine had significant differences between the broilers and Baier layers. The China Agricultural University F(2) population was used in the present study. Body weight and body composition traits were measured in the populations. Primers for the coding region and 5' upstream region of the L-FABP gene were designed according to chicken genomic and cDNA sequence. Polymorphisms were detected by DNA sequencing, and the PCR single-strand conformation polymorphisms method was developed to genotype the F(2) population. The results indicated that the L-FABP gene polymorphisms were associated with abdominal fat weight and percentage of abdominal fat, and the L-FABP gene could be a candidate locus or linked to a major gene(s) that affects fatness traits in the chicken. The results of the current study provided basic molecular information for studying the role of the L-FABP gene in the regulation of lipid metabolism in avian species.

Association between serum levels of soluble receptor for advanced glycation end products and circulating advanced glycation end products in type 2 diabetes

AIMS/HYPOTHESIS

Activation of the receptor for advanced glycation end products (RAGE, also known as AGE-specific receptor [AGER]) has been implicated in the development of diabetic vascular complications. Blockade of RAGE using a soluble form of the receptor (sRAGE) suppressed vascular hyperpermeability and atherosclerosis in animal models. Since little is known about the regulation of endogenous sRAGE levels, we determined whether serum sRAGE is influenced by circulating AGEs and the severity of nephropathy in type 2 diabetic patients.

MATERIALS AND METHODS

We recruited 150 healthy control and 318 diabetic subjects. Diabetic subjects were subdivided into those with proteinuria, microalbuminuria or normoalbuminuria. Serum sRAGE was assayed by ELISA and serum AGEs by competitive ELISA using a polyclonal rabbit antiserum raised against AGE-RNase.

RESULTS

Diabetic subjects had higher sRAGE (1,029.5 pg/ml [766.1-1,423.0] interquartile range vs 1,002.6 [726.5-1,345.3], p<0.05) and AGEs (4.07+/-1.13, SD, unit/ml vs 3.39+/-1.05, p<0.01) than controls. Proteinuric subjects had the highest sRAGE levels and there was a significant trend between the severity of nephropathy and sRAGE (p=0.01). In diabetic subjects, serum log(sRAGE) correlated with AGEs (r=0.27, p<0.001), log(plasma creatinine) (r=0.31, p<0.001), log(urine AER) (r=0.24, p<0.01) and log(triglycerides) (r=0.15, p<0.01). On stepwise linear regression analysis, AGEs and creatinine levels were the main independent determinants of sRAGE concentration.

CONCLUSIONS/INTERPRETATION

Serum sRAGE levels and circulating AGEs are associated with the severity of nephropathy in type 2 diabetic patients. Prospective studies are required to determine whether endogenous sRAGE potentially influences the development of diabetic vascular complications.

Identification of single nucleotide polymorphism of adipocyte fatty acid-binding protein gene and its association with fatness traits in the chicken

Fatty acid-binding proteins (FABP) belong to a superfamily of lipid binding proteins that exhibit a high affinity for long chain fatty acids and appear to function in metabolism and intracellular transportation of lipids. The current study was designed to investigate the effects of the adipocyte (A)-FABP gene on chicken growth and body composition traits. Two F2 resource populations were used in the current study. Body weight and body composition traits were measured in the populations. Primers for the coding region of the A-FABP gene were designed from chicken genomic and cDNA sequences. Polymorphism between parental lines was detected by DNA sequencing, and the PCR-RFLP method was developed to genotype the F2 populations. The results indicated that an A-FABP gene polymorphism was associated with abdominal fat weight and percentage of abdominal fat, and the A-FABP gene could be a candidate locus or linked to a major gene(s) that affects abdominal fat content in the chicken.

Role for macrophage migration inhibitory factor in asthma

Macrophage migration inhibitory factor (MIF) is an immunologic regulator that is expressed in inflammatory and autoimmune disorders. We investigated MIF's role in asthma using genetic approaches in a mouse model and in a cohort of asthma patients. Mice genetically deficient in MIF that were primed and aerosol-challenged with ovalbumin showed less pulmonary inflammation and lower airway hyperresponsiveness than genetically matched, wild-type controls. MIF deficiency also resulted in lower titers of specific IgE, IgG(1), and IgG(2a), and decreased pulmonary, T(H)2 cytokine levels. IL-5 concentrations were lower and corresponded to decreased eosinophil numbers in bronchoalveolar lavage fluid. T cell studies also showed a lower level of antigen-specific responses in MIF-KO versus wild-type mice. In an analysis of 151 white patients with mild, moderate, or severe asthma (Global Initiative for Asthma criteria), a significant association was found between mild asthma and the low-expression, 5-CATT MIF allele. Pharmacologic inhibition of MIF may be beneficial and could be guided by the MIF genotype of affected individuals.

The effects of organic selenium supplementation on the rumen ciliate population in sheep

The effect of selenium supplementation on the rumen protozoan population of sheep was demonstrated. Both the total and generic counts of rumen ciliates in sheep fed a diet with basal Se content (70 microg/kg dry matter) were compared to those of animals given feed supplemented with inorganic (disodium selenite) or organic Se (selenized yeast) (310 microg/kg dry matter). The genera of Entodinium, Isotricha, Dasytricha, Ophryoscolex, Diploplastron and Polyplastron occurred in all sheep except for the control, in which Ophryoscolex was not observed. The population of Ophryoscolex caudatus f. tricoronatus was significantly higher in sheep supplemented with organic Se than in animals given inorganic Se (by 160 %). Supplementation of feed with selenized yeast induced significant growth in the Diploplastron population (by 63 %) while no change occurred in sheep given selenite. The populations of Dasytricha ruminantium and Polyplastron multivesiculatum were higher than control in both Se-supplemented groups. The ciliate population of Entodinium spp. was not influenced by Se supplements. Our results suggest a protective effect of Se feed supplementation on the development of some rumen ciliate species in young ruminants.

Activation of Syk protein tyrosine kinase through interaction with integrin beta cytoplasmic domains

Syk protein tyrosine kinase is essential for immune system development and function [1]and for the maintenance of vascular integrity [2,3]. In leukocytes, Syk is activated by binding to diphosphorylated immune receptor tyrosine-based activation motifs (pITAMs)[1]. Syk can also be activated by integrin adhesion receptors [4,5], but the mechanism of its activation is unknown. Here we report a novel mechanism for Syk's recruitment and activation, which requires that Syk bind to the integrin beta3 cytoplasmic tail. We found that both Syk and the related kinase ZAP-70 bound the beta3 cytoplasmic tail through their tandem SH2 domains. However, unlike Syk binding to pITAMs, this interaction was independent of tyrosine phosphorylation and of the phosphotyrosine binding function of Syk's tandem SH2 domains. Deletion of the four C-terminal residues of the beta3 cytoplasmic tail [beta3(759X)] decreased Syk binding and disrupted its physical association with integrin alphaIIbbeta3. Furthermore, cells expressing alphaIIbbeta3(759X) failed to exhibit Syk activation or lamellipodia formation upon cell adhesion to the alphaIIbbeta3 ligand, fibrinogen. In contrast, FAK phosphorylation and focal adhesion formation were unimpaired by this mutation. Thus, the direct binding of Syk kinase to the integrin beta3 cytoplasmic tail is a novel and functionally significant mechanism for the regulation of this important non-receptor tyrosine kinase.

Hematopoietic reconstitution of SLP-76 corrects hemostasis and platelet signaling through alpha IIb beta 3 and collagen receptors

Mice deficient in the hematopoietic cell-specific adapter protein SLP-76 demonstrate a failure of T cell development and fetal hemorrhage. Although SLP-76-deficient platelets manifest defective collagen receptor signaling, this alone may not explain the observed bleeding diathesis. Because alpha IIb beta 3, the platelet fibrinogen receptor, is required for normal hemostasis, we explored a potential role for SLP-76 in alpha IIb beta 3 signaling. Interaction of soluble or immobilized fibrinogen with normal human or murine platelets triggers rapid tyrosine phosphorylation of SLP-76. Moreover, platelet adhesion to fibrinogen stimulates actin rearrangements, filopodial and lamellipodial extension, and localization of tyrosine phosphorylated proteins to the cell periphery. In contrast, SLP-76-deficient murine platelets bind fibrinogen normally, but spread poorly and exhibit reduced levels of phosphotyrosine. The in vivo bleeding diathesis as well as the defects in platelet responses to fibrinogen and collagen are reversed by retroviral transduction of SLP-76 into bone marrow derived from SLP-76-deficient mice. These studies establish that SLP-76 functions downstream of alpha IIb beta 3 and collagen receptors in platelets. Furthermore, expression of SLP-76 in hematopoietic cells, including platelets, plays a necessary role in hemostasis.

The urinary excretion of selenium in sheep treated with a vasopressin analogue

The renal excretion of selenium was investigated in ewes with an excretion of hypotonic urine (control group) and in ewes with a formation of highly concentrated urine. Chronic stimulation of the urinary concentrating activity of sheep kidneys was induced by a long-term treatment with 1-desamino-8-D-arginine vasopressin (dDAVP), a synthetic analogue of vasopressin with prolonged effects. Young animals with 22 to 25 kg b.w. were fed a normal protein diet providing a daily intake of 129.25 g of crude protein, 12.03 MJ of digestible energy and 0.18 mg of selenium for 3 weeks. The vasopressin treated sheep (n = 11) were given subcutaneous injections of 12.5 micrograms of dDAVP in glycerol twice daily for one week before the clearance measurement of renal functions. The control group (n = 11) was treated with glycerol only. The administration of dDAVP resulted in a highly significant decrease of the urinary flow rate (from 3.19 +/- 0.50 in control group to 0.33 +/- 0.03 mL.min-1 in dDAVP animals, P < 0.001) without changes in the glomerular filtration rate (80.18 +/- 6.36 in controls vs. 77.86 +/- 6.26 mL.min-1, NS). No effects on plasma selenium level were observed (0.17 +/- 0.03 in controls vs. 0.20 +/- 0.03 mumol.L-1, NS) but the amounts of selenium excreted were found to be highly significantly reduced (from 0.29 +/- 0.05 in controls to 0.03 +/- 0.01 nmol.min-1, P < 0.001) in dDAVP treated sheep. Despite a large reduction in urinary flow rate, the selenium concentration in urine was actually the same in both groups (0.09 +/- 0.01 mumol.L-1) resulting in a sharp fall in the renal clearance of selenium (2.20 +/- 0.54 in controls vs. 0.18 +/- 0.03 mL.min-1, P < 0.01) due to dDAVP. This seems to be a consequence of the large increase in the selenium solvent drag induced by a vasopressin treatment. The results presented suggest that vasopressin may contribute to maintenance of the selenium balance in sheep via its effects on renal function.

Observation of the breakup of a prechirped N-soliton in an optical fiber

We present what is believed to be the first experimental evidence showing the breakup of a chirped N-soliton pulse into an ordered train of fundamental solitons, as predicted by theory. We also present numerical experiments that confirm this phenomenon. Implications for optical communications systems that use chirped pulses are discussed.

Lethal encephalitozoonosis in cyclophosphamide-treated rabbits

Encephalitozoonosis is an opportunistic infection in animals and humans. Its clinical form is observed in immunosuppressed hosts. We studied the occurrence of the manifest form of rabbit microsporidiosis under cyclophosphamide immunomodulation in 40 New Zealand rabbits. The experimental animals were intraperitoneally infected with 5 x 10(7) Encephalitozoon cuniculi spores. Two weeks after infection the animals were treated intraperitoneally with cyclophosphamide, first with 50 mg/kg and then with 15 mg/kg weekly during the 12-week experimental period. Positive controls were either E. cuniculi-infected or cyclophosphamide-immunosuppressed animals. The negative control rabbits remained untreated. Both clinical signs of encephalitozoonosis and depression of peripheral blood cell count developed between weeks 4 and 6 in the experimental animals which died during week 6 of the experiment. No clinical signs compatible with encephalitozoonosis were observed in any of the controls. The results suggest that immunosuppression induced by cyclophosphamide can give rise to a lethal form of encephalitozoonosis.

Identification of a novel integrin signaling pathway involving the kinase Syk and the guanine nucleotide exchange factor Vav1

BACKGROUND

. Integrins induce the formation of large complexes of cytoskeletal and signaling proteins, which regulate many intracellular processes. The activation and assembly of signaling complexes involving focal adhesion kinase (FAK) occurs late in integrin signaling, downstream from actin polymerization. Our previous studies indicated that integrin-mediated activation of the non-receptor tyrosine kinase Syk in hematopoietic cells is independent of FAK and actin polymerization, and suggested the existence of a distinct signaling pathway regulated by Syk.

RESULTS

. Multiple proteins were found to be activated by Syk, downstream of engagement of the platelet/megakaryocyte-specific integrin alphaIIbbeta3. The guanine nucleotide exchange factor Vav1 was inducibly phosphorylated in a Syk-dependent manner in cells following their attachment to fibrinogen. Together, Syk and Vav1 triggered lamellipodia formation in fibrinogen-adherent cells and both Syk and Vav1 colocalized with alphaIIbbeta3 in lamellipodia but not in focal adhesions. Additionally, Syk and Vav1 cooperatively induced activation of Jun N-terminal kinase (JNK), extracellular-signal-regulated kinase 2 (ERK2) and the kinase Akt, and phosphorylation of the oncoprotein Cbl in fibrinogen-adherent cells. Activation of all of these proteins by Syk and Vav1 was not dependent on actin polymerization.

CONCLUSIONS

. Syk and Vav1 regulate a unique integrin signaling pathway that differs from the FAK pathway in its proximity to the integrin itself, its localization to lamellipodia, and its activation, which is independent of actin polymerization. This pathway may regulate multiple downstream events in hematopoietic cells, including Rac-induced lamellipodia formation, tyrosine phosphorylation of Cbl, and activation of JNK, ERK2 and the phosphatidylinositol 3'-kinase-regulated kinase Akt.

Cloning, functional expression and purification of endo-beta-galactosidase from Flavobacterium keratolyticus

Endo-beta-galactosidase (EC 3.2.1.103) is an enzyme that hydrolyzes internal endo-beta-galactosyl linkages in keratan sulfate, and glycoconjugates with N-acetyl-lactosamine repeating units. Here, we report the cloning of the endo-beta-galactosidase-encoding gene from Flavobacterium keratolyticus, its expression in Escherichia coli and the purification of the enzyme. The enzyme was purified over 15000-fold to apparent homogeneity. The purified endo-beta-galactosidase consists of a single band of about 43kDa on SDS-PAGE and has a specific activity of 148micro/mg. Based on peptide sequences derived from the purified enzyme, a full-length clone encoding endo-beta-galactosidase was isolated from F. keratolyticus genomic DNA. The gene contains a single open reading frame coding for a protein of 422 amino acid residues with a putative N-terminal signal peptide. Its authenticity was confirmed by colinearity of deduced amino acid sequences with the peptide sequences, and synthesis of enzyme in E. coli.

Subpopulations of lymphocytes in cattle naturally infected with papillomavirus

Subpopulations of blood lymphocytes (CD2, CD4, CD8, WC1 and IgM-mu chain) were evaluated in clinically manifested bovine papillomatosis. Significantly lower numbers of CD2 (44.7%), CD4 (22.8%) and a lower ratio of CD4/CD8 (1.5) were found in animals with tumours compared to a group of cattle free of papillomas (62.3%, 34%, and 2.3, respectively). On the other hand, significantly higher numbers of gamma/delta+ T lymphocytes (9.6%) and of lymphocytes expressing IgM molecules (35%) were observed in the group of tumour-bearing cattle than in the papilloma-free group (4.8% and 22.1%, respectively). The animals came from a region characterised by elevated concentrations of copper, zinc, arsenic, cadmium and lead in the soil and in the organs of animals. It is supposed that environmental factors predisposed the animals to the development of papillomas.

RhoA and the function of platelet integrin alphaIIbbeta3

Integrins respond to "inside-out" signals, which enable them to bind adhesive ligands, and ligand binding initiates "outside-in" signals that mediate anchorage-dependent cellular responses. RhoA is a GTPase that regulates certain actin rearrangements and transcriptional events. It has also been implicated in integrin signaling, but the exact relationship is not understood. To examine this further, platelets were incubated with C3 exoenzyme to adenine diphosphate (ADP)-ribosylate and inactivate RhoA, and the function of integrin alphaIIbbeta3 was studied. Despite inactivation of >/= 90% of RhoA, platelets exhibited normal inside-out signaling, as monitored by agonist-induced binding of a fibrinogen-mimetic anti-alphaIIbbeta3 antibody and normal fibrinogen-dependent aggregation. On the other hand, RhoA inactivation decreased the adhesion of agonist-stimulated platelets to fibrinogen (P < .04) and the formation of vinculin-rich focal adhesions in platelets that did adhere (P < .001). These effects were selective because fibrin clot retraction, a response also dependent on alphaIIbbeta3 and actin contractility, was unaffected by C3, as was the content of F-actin in resting or agonist-stimulated platelets. Similar results were obtained in a Chinese hamster ovary (CHO) cell model system of alphaIIbbeta3: C3 exoenzyme (or overexpression of dominant-negative N19RhoA) failed to influence integrin activation state, but it blocked the formation of focal adhesions in cells spread on fibrinogen. These studies establish that RhoA plays a highly selective role in alphaIIbbeta3 signaling, and they identify a subset of responses to integrin ligation that may be uniquely dependent on the actin rearrangements regulated by this GTPase.

Micropuncture study on urea movements in the kidney cortical tubules of low protein fed sheep

Micropuncture studies of late proximal, early and late distal cortical tubules were carried out on kidneys of normal (NP) and low (LP) protein fed sheep in order to investigate the participation of these segments in the urea sparing induced by protein restriction in the diet. A low protein diet induced significant reductions in the fractional (-54%) and total (-84%) urea excretion, revealing an enhanced capacity for urea conservation. Micropuncture data did not show any difference in the proximal tubule functions between both groups of sheep. In distal cortical tubules the fractional delivery of urea (early distal, 0.61 +/- 0.06 for NP and 0.77 +/- 0.06 for LP sheep, not significant (NS); late distal, 0.45 +/- 0.07 for NP and 0.71 +/- 0.09 for LP sheep, P < 0.05) showed a relatively larger amount of urea present in the late distal tubule of protein restricted sheep. The tubular fluid-to-plasma inulin ratio in the late distal tubule was found to be lower in LP sheep (4.33 +/- 0.23 versus 8.58 +/- 0.9 in NP sheep, P < 0.01). The tubular flow rate, reduced in the early distal tubules of LP sheep (10.87 +/- 0.99 versus 18.92 +/- 2.58 nL.min-1 in NP sheep, P < 0.05), was not different in the late distal tubules from values in normally fed animals (6.65 +/- 0.90 versus 7.73 +/- 0.94 nL.min-1 in NP sheep, NS). These findings suggest a decreased distal water reabsorption coincident with the relatively larger amounts of intraluminal urea in LP sheep. This relatively larger urea delivery to the initial collecting duct could increase the subsequent urea reabsorption in protein restricted sheep.

The renal response of sheep to intraportal infusion of glucagon

The effects on renal functions of infusing glucagon (100 ng kg-1 min-1) into the portal vein system were studied in young anaesthetized sheep kept on a diet with normal protein and digestible energy contents. The clearance measurements of the left kidney functions showed a decreased urine flow rate (from 0.36 +/- 0.04 to 0.18 +/- 0.03 ml min-1; P < 0.01) within the first 10 min of glucagon infusion, falling to 0.07 +/- 0.02 ml min-1 (P < 0.01) during the next 10 min. The glomerular filtration rate also decreased from 17.56 +/- 2.92 ml min-1 to its lowest value, 3.34 +/- 1.02 ml min-1, (P < 0.01) after 20 min of glucagon infusion. Decreases in urea excretion (from 53.1 +/- 6.46 to 3.82 +/- 1.27 mumol min-1; P < 0.01) and osmotic clearance (from 0.67 +/- 0.13 to 0.09 +/- 0.02 ml min-1; P < 0.01) occurred during the first 20 min. The plasma level of glucose increased from 4.01 +/- 0.53 to 8.33 +/- 1.12 mmol l-1 (P < 0.05) 20 min after the start of glucagon infusion. Twenty minutes after the start of glucagon infusion, the values of all the parameters measured began to recover, although they did not reach the control level, even after 1 h. Blood pressure was stable during the whole experiment. The results show that the effects of intraportally infused glucagon on kidney functions in sheep are the opposite of those obtained from similar experiments in laboratory animals with simple stomachs or in humans.

Osmo-mechanically sensitive phosphatidylinositol signaling regulates a Ca2+ influx channel in renal epithelial cells

Regulation of dihydropyridine (nifedipine)-sensitive calcium influx was studied in rabbit culture proximal tubule cells using the fura 2 fluorescence ratio technique. "Osmo-mechanically induced" swelling of cells by exposure to hypotonic medium (220 mosmol/kgH2O) caused a rapid rise in intracellular calcium that was predominantly due to influx of calcium via both dihydropyridine-sensitive (nifedipine-sensitive) and -insensitive calcium influx pathways. The dihydropyridine-sensitive pathway was regulated, in part, by the phosphatidylinositol signaling pathway. Inhibition of phospholipase C by treatment with 2-nitro-4-carboxyphenyl-N,N-diphenylcarbamate (NCDC), inhibition of protein kinase C (PKC) by staurosporine, or long-term (24 h) treatment with phorbol 12-myristate 13-acetate (PMA) to downregulate PKC abolished most of the osmo-induced, dihydropyridine-sensitive calcium influx signal. Short-term (seconds) PMA treatment to activate PKC produced a marked stimulation of both dihydropyridine-sensitive and -insensitive calcium influx in isotonic (2- to 3-fold stimulation) and hypotonic (5-fold stimulation) conditions. In contrast, elevation of adenosine 3',5'-cyclic monophosphate (cAMP) by treatment with forskolin or inhibition of protein kinase A (PKA) by treatment with the cAMP analog, Rp-8-CPT-cAMPS (the Rp diastereoisomer of adenosine 3',5'-cyclic monophosphothionate), had little or no influence on calcium influx, including dihydropyridine-sensitive calcium influx. It is concluded that osmo-mechanical stress activates a dihyropyridine-sensitive calcium influx pathway that is predominantly regulated via the phosphatidylinositol signaling pathway and PKC and not through the cAMP/PKA signaling pathway.

[The effect of a low-protein diet on the epithelium of nephron segments in sheep]

Changes in the epithelium thickness of proximal and distal convoluted tubule of cortex, thin descending limb of Henle loop from inner stripe of outer medulla, thick ascending limb from outer stripe of outer medulla and of collecting duct from inner medulla were investigated in young growing sheep fed a low protein diet (LP). Sheep on LP-diet were given a daily ration with 5.73 g of nitrogen and 6.13 MJ of digestible energy (DE) while the daily intake of control group was 19.51 g of N and 12.29 MJ of DE. Both groups of animals were fed these diets at least 6 weeks before collection of kidneys. Morphometric analysis with digitizing tablet showed that intake of LP-diet resulted in significant reduction of epithelium thickness in both distal convoluted tubule and thick ascending limb while the epithelium of collecting duct was found to be thicker. No changes of the epithelium dimensions were determined in proximal tubule and in thin descending limb of Henle loop. Presented results point to the morphological expression of the adaptation of sheep kidneys to a low dietary protein intake which is associated with the increased renal reabsorption of urea.