Antarctic teleosts with and without hemoglobin behaviorally mitigate deleterious effects of acute environmental warming.

Recent studies forecast that many ectothermic animals, especially aquatic stenotherms, may not be able to thrive or even survive predicted climate change. These projections, however, generally do not call much attention to the role of behavior, an essential thermoregulatory mechanism of many ectotherms. Here we characterize species-specific locomotor and respiratory responses to acute ambient warming in two highly stenothermic Antarctic Notothenioid fishes, one of which (Chaenocephalus aceratus) lacks hemoglobin and appears to be less tolerant to thermal stress as compared to the other (Notothenia coriiceps), which expresses hemoglobin. At the onset of ambient warming, both species perform distinct locomotor maneuvers that appear to include avoidance reactions. In response to unavoidable progressive hyperthermia, fishes demonstrate a range of species-specific maneuvers, all of which appear to provide some mitigation of the deleterious effects of obligatory thermoconformation and to compensate for increasing metabolic demand by enhancing the efficacy of branchial respiration. As temperature continues to rise, Chaenocephalus aceratus supplements these behaviors with intensive pectoral fin fanning which may facilitate cutaneous respiration through its scaleless integument, and Notothenia coriiceps manifests respiratory-locomotor coupling during repetitive startle-like maneuvers which may further augment gill ventilation. The latter behaviors, found only in Notothenia coriiceps, have highly stereotyped appearance resembling Fixed Action Pattern sequences. Altogether, this behavioral flexibility could contribute to the reduction of the detrimental effects of acute thermal stress within a limited thermal range. In an ecologically relevant setting, this may enable efficient thermoregulation of fishes by habitat selection, thus facilitating their resilience in persistent environmental change.

Comparison between Bilistick System and transcutaneous bilirubin in assessing total bilirubin serum concentration in jaundiced newborns.

OBJECTIVE: To compare the performance and accuracy of the JM-103 transcutaneous bilirubinometer and Bilistick System in measuring total serum bilirubin for the early identification of neonatal hyperbilirubinemia. STUDY DESIGN: The study was performed on 126 consecutive term and near-term (⩾36 weeks' gestational age) jaundiced newborns in Cairo University Children Hospital NICU, Egypt. Total serum bilirubin was assayed concurrently by the clinical laboratory and Bilistick System and estimated using the JM-103 transcutaneous bilirubin instrument. Bland-Altman analysis was used to evaluate the agreement between determinations. RESULT: The limits of agreement of the Bilistick System (-5.8 to 3.3 mg dl-1) and JM-103 system (-5.4 to 6.0 mg dl-1) versus the clinical laboratory results were similar. CONCLUSION: The Bilistick System is an accurate alternative to transcutaneous (TcB) determination for early diagnosis and proper management of the neonatal jaundice.

A decision-making tool for exchange transfusions in infants with severe hyperbilirubinemia in resource-limited settings.

Late presentation and ineffective phototherapy account for excessive rates of avoidable exchange transfusions (ETs) in many low- and middle-income countries. Several system-based constraints sometimes limit the ability to provide timely ETs for all infants at risk of kernicterus, thus necessitating a treatment triage to optimize available resources. This article proposes a practical priority-setting model for term and near-term infants requiring ET after the first 48 h of life. The proposed model combines plasma/serum bilirubin estimation, clinical signs of acute bilirubin encephalopathy and neurotoxicity risk factors for predicting the risk of kernicterus based on available evidence in the literature.

Ca(2+) permeation and/or binding to CaV1.1 fine-tunes skeletal muscle Ca(2+) signaling to sustain muscle function.

BACKGROUND: Ca(2+) influx through CaV1.1 is not required for skeletal muscle excitation-contraction coupling, but whether Ca(2+) permeation through CaV1.1 during sustained muscle activity plays a functional role in mammalian skeletal muscle has not been assessed. METHODS: We generated a mouse with a Ca(2+) binding and/or permeation defect in the voltage-dependent Ca(2+) channel, CaV1.1, and used Ca(2+) imaging, western blotting, immunohistochemistry, proximity ligation assays, SUnSET analysis of protein synthesis, and Ca(2+) imaging techniques to define pathways modulated by Ca(2+) binding and/or permeation of CaV1.1. We also assessed fiber type distributions, cross-sectional area, and force frequency and fatigue in isolated muscles. RESULTS: Using mice with a pore mutation in CaV1.1 required for Ca(2+) binding and/or permeation (E1014K, EK), we demonstrate that CaV1.1 opening is coupled to CaMKII activation and refilling of sarcoplasmic reticulum Ca(2+) stores during sustained activity. Decreases in these Ca(2+)-dependent enzyme activities alter downstream signaling pathways (Ras/Erk/mTORC1) that lead to decreased muscle protein synthesis. The physiological consequences of the permeation and/or Ca(2+) binding defect in CaV1.1 are increased fatigue, decreased fiber size, and increased Type IIb fibers. CONCLUSIONS: While not essential for excitation-contraction coupling, Ca(2+) binding and/or permeation via the CaV1.1 pore plays an important modulatory role in muscle performance.

Ligands for FKBP12 increase Ca2+ influx and protein synthesis to improve skeletal muscle function.

Rapamycin at high doses (2-10 mg/kg body weight) inhibits mammalian target of rapamycin complex 1 (mTORC1) and protein synthesis in mice. In contrast, low doses of rapamycin (10 µg/kg) increase mTORC1 activity and protein synthesis in skeletal muscle. Similar changes are found with SLF (synthetic ligand for FKBP12, which does not inhibit mTORC1) and in mice with a skeletal muscle-specific FKBP12 deficiency. These interventions also increase Ca(2+) influx to enhance refilling of sarcoplasmic reticulum Ca(2+) stores, slow muscle fatigue, and increase running endurance without negatively impacting cardiac function. FKBP12 deficiency or longer treatments with low dose rapamycin or SLF increase the percentage of type I fibers, further adding to fatigue resistance. We demonstrate that FKBP12 and its ligands impact multiple aspects of muscle function.

Bilistick: a low-cost point-of-care system to measure total plasma bilirubin.

BACKGROUND: Severe neonatal hyperbilirubinemia, with consequent encephalopathy, remains a common cause of morbidity and death in many regions of the world. Poor access to clinical laboratory resources and screening programs to measure plasma bilirubin levels is a major contributor to delayed treatment in developing countries, and the cost of existing point-of-care screening instruments precludes their dissemination. OBJECTIVES: We are evaluating the accuracy of a low-cost, minimally invasive point-of-care system (Bilistick) requiring a 25-µl blood sample that could be used in low-resource environments to evaluate patients with neonatal jaundice. METHODS: We compared plasma bilirubin levels in divided blood samples by clinical laboratories and by Bilistick at two medical centers serving term and near-term newborns from ethnically different populations. RESULTS: 118 neonates with bilirubin levels ranging from 24.8 to 501.0 µmol/l were analyzed. The mean bilirubin concentration (±SD) was 215.6 ± 85.5 µmol/l for Bilistick and 226.1 ± 86.4 µmol/l by laboratory determination. Pearson's correlation coefficient between all paired results was 0.961, and the Bland-Altman analysis showed a mean difference of 10.3 µmol/l with a 95% interval of agreement of -38.0 to 58.7 µmol/l. CONCLUSION: Bilistick is a minimally invasive method for measuring total bilirubin concentration over a wide range of values and should provide an affordable and accurate system for pre-discharge and follow-up screening of jaundiced infants, particularly in low-resource environments.

Root causes for late presentation of severe neonatal hyperbilirubinaemia in Egypt.

This study aimed to understand the reasons for late presentation of cases of severe neonatal hyperbilirubinaemia. We administered a questionnaire to parents of 130 infants with severe jaundice admitted to Cairo University Children's Hospital neonatal intensive care unit at age > or = 6 days over an 18-month period. Although 125 infants (96.2%) were delivered in a health care facility, no discharge physical examination was performed in 99/125 cases (79.2%). No parent was given instructions about neonatal jaundice and no follow-up appointments were scheduled. Parents of 109 infants sought medical advice prior to hospital readmission; most babies were assessed clinically, but serum bilirubin was measured in only one-quarter of cases (28/109). Medical advice included placing the infant under a neon lamp at home (87/109 cases), advice to supplement breastfeeding (75/109) and prescribed medications, including vitamins (15/109). Increasing the availability of inexpensive point-of-care diagnostic instruments and phototherapy units in health care facilities are urgently needed.

AICAR prevents heat-induced sudden death in RyR1 mutant mice independent of AMPK activation.

Mice with a knock-in mutation (Y524S) in the type I ryanodine receptor (Ryr1), a mutation analogous to the Y522S mutation that is associated with malignant hyperthermia in humans, die when exposed to short periods of temperature elevation (≥37 °C). We show here that treatment with 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) prevents this heat-induced sudden death in this mouse model. The protection by AICAR is independent of AMP-activated protein kinase (AMPK) activation and results from a newly identified action of the compound on mutant Ryr1 to reduce Ca(2+) leak from the sarcoplasmic reticulum to the sarcoplasm. AICAR thus prevents Ca(2+)-dependent increases in the amount of both reactive oxygen species (ROS) and reactive nitrogen species (RNS) that act to further increase resting Ca(2+) concentrations. If unchecked, the temperature-driven increases in resting Ca(2+) concentrations and the amounts of ROS and RNS create an amplifying cycle that ultimately triggers sustained muscle contractions, rhabdomyolysis and death. Although antioxidants are effective in reducing this cycle in vitro, only AICAR prevents heat-induced death in vivo. Our findings suggest that AICAR is probably effective in prophylactic treatment of humans with enhanced susceptibility to exercise- and/or heat-induced sudden death associated with RYR1 mutations.

KCa1.1 potassium channels regulate key proinflammatory and invasive properties of fibroblast-like synoviocytes in rheumatoid arthritis.

Fibroblast-like synoviocytes (FLS) play important roles in the pathogenesis of rheumatoid arthritis (RA). Potassium channels have regulatory roles in many cell functions. We have identified the calcium- and voltage-gated KCa1.1 channel (BK, Maxi-K, Slo1, KCNMA1) as the major potassium channel expressed at the plasma membrane of FLS isolated from patients with RA (RA-FLS). We further show that blocking this channel perturbs the calcium homeostasis of the cells and inhibits the proliferation, production of VEGF, IL-8, and pro-MMP-2, and migration and invasion of RA-FLS. Our findings indicate a regulatory role of KCa1.1 channels in RA-FLS function and suggest this channel as a potential target for the treatment of RA.

Root causes for late presentation of severe neonatal hyperbilirubinaemia in Egypt

This study aimed to understand the reasons for late presentation of cases of severe neonatal hyperbilirubinaemia. We administered a questionnaire to parents of 130 infants with severe jaundice admitted to Cairo University Children's Hospital neonatal intensive care unit at age >/= 6 days over an 18-month period. Although 125 infants [96.2%] were delivered in a health care facility, no discharge physical examination was performed in 99/125 cases [79.2%]. No parent was given instructions about neonatal jaundice and no follow-up appointments were scheduled. Parents of 109 infants sought medical advice prior to hospital readmission; most babies were assessed clinically, but serum bilirubin was measured in only one-quarter of cases [28/109]. Medical advice included placing the infant under a neon lamp at home [87/109 cases], advice to supplement breastfeeding [75/109] and prescribed medications, including vitamins [15/109]. Increasing the availability of inexpensive pointof-care diagnostic instruments and phototherapy units in health care facilities are urgently needed

Root causes for late presentation of severe neonatal hyperbilirubinaemia in Egypt

This study aimed to understand the reasons for late presentation of cases of severe neonatal hyperbilirubinaemia. We administered a questionnaire to parents of 130 infants with severe jaundice admitted to Cairo University Children's Hospital neonatal intensive care unit at age >/= 6 days over an 18-month period. Although 125 infants [96.2%] were delivered in a health care facility, no discharge physical examination was performed in 99/125 cases [79.2%]. No parent was given instructions about neonatal jaundice and no follow-up appointments were scheduled. Parents of 109 infants sought medical advice prior to hospital readmission; most babies were assessed clinically, but serum bilirubin was measured in only one-quarter of cases [28/109]. Medical advice included placing the infant under a neon lamp at home [87/109 cases], advice to supplement breastfeeding [75/109] and prescribed medications, including vitamins [15/109]. Increasing the availability of inexpensive point-of-care diagnostic instruments and phototherapy units in health care facilities are urgently needed

Methods to study CFTR protein in vitro.

CFTR is a cyclic AMP and nucleotide-related chloride-selective channel with a low unitary conductance. Many of the physiological roles of CFTR are effectively studied in intact cells and tissues. However, there are also several clear advantages to the application of cell-free technologies to the study of the biochemical and biophysical properties of CFTR. When expressed in heterologous cells, CFTR is processed relatively poorly, depending, however, on the cell-type analysed. In some cells, only 20-25% of the protein which is initially synthesized exits the endoplasmic reticulum to insert into the cell membrane [Cell 83 (1995) 121; EMBO J. 13 (1994) 6076]. Further, many of the disease-causing mutants of CFTR result in even lower processing efficiencies. Therefore, several procedures have been developed to study regulated CFTR channel function expressed in microsomal membranes and following its purification and reconstitution. These experimental approaches and their application are discussed here.

The patch-clamp and planar lipid bilayer techniques: powerful and versatile tools to investigate the CFTR Cl- channel.

Using the patch-clamp (PC) and planar lipid bilayer (PLB) techniques the molecular behaviour of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel can be visualised in real-time. The PC technique is a highly powerful and versatile method to investigate CFTR's mechanism of action, interaction with other proteins and physiological role. Using the PLB technique, the structure and function of CFTR can be investigated free from the influence of other proteins. Here we discuss how these techniques are employed to investigate the CFTR Cl- channel with special emphasis on its permeation, conduction and gating properties.

The acute effect of intravenously administered recombinant human erythropoietin on the immune response of uremic patients maintained on regular hemodialysis.

The uremic patient on regular hemodialysis (RHD) is subjected to a wide range of immune modulators including the uremic state per se, multiple transfusions and exposure to bioincompatible materials and endotoxins. Erythropoietin (EPO) therapy may raise concern about its potential influence on this complex scenario. To envisage this issue, 15 adequately selected patients, stable on RHD, were randomly assigned in a 2:1 ratio into EPO and placebo groups. After initial assessment and determination of baseline values, they received, in a double-blind manner, either EPO or normal saline as an intravenous bolus immediately after termination of dialysis for 30 successive sessions. Thirty minutes later, following sessions 1, 10, 20, and 30, samples were obtained for determination of blood counts, red cell indices, peripheral lymphocyte counts (PLC), CD4/CD8 ratios, blood EPO levels, and serum concentrations of interleukins (IL) IL-2r, IL-3, and IL-6, tumor necrosis factor (TNFs and TNFalpha), and neopterin (NPT). Blood EPO levels displayed the predicted rise in the EPO group, which correlated with partial improvement of red cell parameters. The mean total leukocyte count and PLCs was significantly increased in the EPO group (p < 0.05) but not in the placebo group. CD4/CD8 ratios were not significantly changed in either group. The serum concentrations of IL-2r, IL-3, and NPT remained fairly stable while that of IL-6 was widely variable in both study groups. The mean serum concentrations of TNF and particularly TNFalpha showed a steady and statistically significant increment in the EPO group from 6 to 41 pg/ml (p < 0.05) and 93 to 128 pg/ml (p < 0.03), respectively. No significant change was noticed in the control group. It is concluded that intravenous administration of EPO under the conditions of this study may have an immune stimulating effect. This is shown by the release of TNFs, which in turn may be responsible, through different potential mechanisms, for the increase in the mean peripheral neutrophil count and the blunting of erythroid responsiveness to EPO therapy.

Immunoglobulin-A and the pathogenesis of schistosomal glomerulopathy.

Several observations suggest that the evolution of schistosomal glomerulopathy into clinically overt and progressive disease may involve pathogenetic mechanisms other than simple glomerular deposition of parasitic antigens. In a previous study, IgA was suggested to be a mediator of late glomerular lesions in this disease. This issue is further addressed in this work. The study includes 32 patients with hepatosplenic schistosomiasis, of whom 16 had overt glomerular involvement, along with four control groups: (a) 15 healthy volunteers; (b) 15 patients with simple intestinal mansoniasis; (c) 17 patients with non-schistosomal chronic liver disease; and (d) 21 subjects with primary nephrotic syndrome not associated with schistosomiasis. Routine assessment was done for all subjects including confirmatory tests for schistosomal infection, liver and renal function tests, hepatitis viral markers and abdominal ultrasonography. The total serum concentrations of IgG, IgM, IgA were measured, as well as their respective circulating immune complexes, rheumatoid factors, anti-gliadin- and anti-DNA-antibodies. Liver and renal biopsies were obtained from the relevant groups and studied by light microscopy. Renal biopsies were also examined by immunofluorescence. Patients with simple intestinal schistosomiasis had a significant increase in IgM antigliadin antibodies. Those complicated with hepatosplenic involvement also had a significant increase in the mean IgG anti-gliadin antibodies, IgG rheumatoid factor and IgM anti-DNA activity. Cases further complicated by overt glomerular disease showed a distinct IgA predominance, mainly expressed in the serum anti-gliadin antibody pool and anti-DNA activity. This profile was essentially similar to that observed in control cirrhotics. There was a significant increase in the frequency of IgA glomerular deposits in renal biopsies obtained from patients with overt schistosomal glomerulopathy, in contrast to control nephrotics. The deposits were mainly mesangial, but were also encountered in subendothelial, subepithelial and peritubular locations. Their frequency was significantly higher with more advanced lesions as seen by light microscopy. The relevance of these data is discussed, leading to the following conclusions: (a) serum IgA-anti-gliadin and -anti-DNA antibodies, and glomerular IgA deposits are markers of significant renal involvement in patients with hepatosplenic schistosomiasis. (b) IgA may be involved in the pathogenesis of advanced glomerular pathology when superimposed on parasite-induced lesions. (c) There is a significant increase in serum auto-reactivity in hepatosplenic schistosomiasis, which may also have pathogentic implications. (d) Increased production by the inflammatory bowel lesions, impaired clearance by the fibrotic livers and probable switching of immunoglobulin synthesis are suggested to explain the observed IgA predominance in those who develop renal complications.

Glycosylated proteins in diabetic nephropathy.

This study was carried out on 55 diabetic patients, 20 of whom had diabetic nephropathy, and 10 controls. Glycosylated haemoglobin, glycosylated serum protein, glucoprotein, serum protein electrophoresis, blood urea, serum creatinine and beta 2-microglobulin were measured. A significant increase of glucoprotein was observed in patients with diabetic nephropathy. No correlation was found between glycosylated serum protein and glycosylated haemoglobin and duration of diabetes. Glycosylated serum protein showed a positive correlation with beta 2-microglobulin, indicating a link between renal involvement and the rise in glycosylated serum protein. Whether there is a pathogenic relation between glycosylated serum protein and the development of nephropathy awaits further evidence.

Human leukocyte antigen in genodermatosis.

Tissue typing performed on the lymphocytes of 41 patients, including: 23 patients with ichthyosis (15 of autosomal dominant and 8 of the x-linked variety; 8 patients with tuberous sclerosis (epiloia); and 10 patients with acrodermatitis enteropathica (AEP). In addition, tissue typing was performed for a control group of 80 healthy unrelated subjects of the same ethnic origin as the patients. A significant increase of A2 antigen or its crossreacting antigen A28 was detected among the three diseases studied. A significant increase of HLA-A2 antigen was found in autosomal dominant ichthyosis, while the x-linked variety showed significant association with HLA-Cw2. A significant association with HLA-A28 antigen was noticed in both epiloia and AEP. The suggested mechanisms of such association may be referred to as incidental genetic linkage with mutants causing disease or deficiency.

Altered cell mediated immunity in atrophic rhinitis.

Cellular immunity was studied in patients with atrophic rhinitis using the in vitro leucocyte migration and the spontaneous rosette tests. Cellular hypersensitivity to crude nasal homogenate was detected in 90 per cent of our cases as shown by inhibition of the leucocyte migration. The spontaneous rosette test showed a reduction in the number of T-cells forming rosettes which reflects a decrease in the absolute number of T-lymphocytes. This altered cellular reactivity or loss of tolerance to nasal tissues may be precipitated primarily by virus infection, malnutrition and/or immuno-deficiency which trigger a destructive auto-immune process with the release of antigen(s) of nasal mucosa into the circulation.

Relation of the heat resistance of salmonellae to the water activity of the environment.

The effect of water activity (a(w)) on the heat resistance of eight strains of Salmonella was studied. Heat resistance of the organisms increased as the a(w) of the heating menstruum was reduced. Sucrose afforded the cells a greater degree of protection than did fructose, glycerol, and sorbitol. A direct correlation between a(w) and heat resistance could not be established over the range of a(w) levels tested in this study. There was variation among the strains of salmonellae in the magnitude of the increase in heat resistance as the a(w) level was reduced. All strains of Salmonella tested showed a greater increase in heat resistance than S. senftenberg 775W as the environment became drier. Washed cells had D values 25 to 75% lower than unwashed cells. Prior growth of the organisms in media with a reduced a(w) increased the heat resistance of the organisms when glycerol, but not when sucrose, was the controlling substance.