Life-history characteristics influence physiological strategies to cope with hypoxia in Himalayan birds.

Hypobaric hypoxia at high elevation represents an important physiological stressor for montane organisms, but optimal physiological strategies to cope with hypoxia may vary among species with different life histories. Montane birds exhibit a range of migration patterns; elevational migrants breed at high elevations but winter at low elevations or migrate further south, while high-elevation residents inhabit the same elevation throughout the year. Optimal physiological strategies to cope with hypoxia might therefore differ between species that exhibit these two migratory patterns, because they differ in the amount time spent at high elevation. We examined physiological parameters associated with blood-oxygen transport (haemoglobin concentration and haematocrit, i.e. the proportion of red blood cells in blood) in nine species of elevational migrants and six species of high-elevation residents that were sampled along a 2200 m (1000-3200 m) elevational gradient. Haemoglobin concentration increased with elevation within species regardless of migratory strategy, but it was only significantly correlated with haematocrit in elevational migrants. Surprisingly, haemoglobin concentration was not correlated with haematocrit in high-elevation residents, and these species exhibited higher mean cellular haemoglobin concentration than elevational migrants. Thus, alternative physiological strategies to regulate haemoglobin concentration and blood O2 carrying capacity appear to differ among birds with different annual elevational movement patterns.

Expression of antisense RNA against initiation factor eIF-4E mRNA in HeLa cells results in lengthened cell division times, diminished translation rates, and reduced levels of both eIF-4E and the p220 component of eIF-4F.

HeLa cells were transformed to express antisense RNA against initiation factor eIF-4E mRNA from an inducible promoter. In the absence of inducer, these cells (AS cells) were morphologically similar to control cells but grew four- to sevenfold more slowly. Induction of antisense RNA production was lethal. Both eIF-4E mRNA and protein levels were reduced in proportion to the degree of antisense RNA expression, as were the rates of protein synthesis in vivo and in vitro. Polysomes were disaggregated with a concomitant increase in ribosomal subunits. Translation in vitro was restored by addition of the initiation factor complex eIF-4F but not by eIF-4E alone. Immunological analysis revealed that the p220 component of eIF-4F was decreased in extracts of AS cells and undetectable in AS cells treated with inducer, suggesting that p220 and eIF-4E levels are coordinately regulated. eIF-4A, another component of eIF-4F, was unaltered.

Akt inhibition upregulates FasL, downregulates c-FLIPs and induces caspase-8-dependent cell death in Jurkat T lymphocytes.

In T lymphocytes, the role of Akt in regulating Fas/Fas ligand (FasL)-mediated apoptotic signaling and death is not clearly understood. In this study, we observed that inhibition of Akt causes enhanced expression of FasL mRNA and protein and increased death-inducing signaling complex (DISC) formation with Fas-associated death domain (FADD) and procaspase-8 recruitment. Also, caspase-8 was activated at the DISC with accompanying decrease in c-FLIPs expression. FasL neutralizing antibody significantly decreased apoptotic death in the Akt-inhibited T cells. Additionally, Akt inhibition-induced Fas signaling was observed to link to the mitochondrial pathway via Bid cleavage. Further, inhibition of caspase-8 activity effectively blocked the loss of mitochondrial membrane potential and DNA fragmentation, suggesting that DISC formation and subsequent caspase-8 activation are critical initiating events in Akt inhibition-induced apoptotic death in T lymphocytes. These data demonstrate yet another important survival function governed by Akt kinase in T lymphocytes, which involves the regulation of FasL expression and consequent apoptotic signaling.

Linoleic acid activates nuclear transcription factor-kappa B (NF-kappa B) and induces NF-kappa B-dependent transcription in cultured endothelial cells.

High dietary intakes of unsaturated fats may be atherogenic by disrupting normal functions of the vascular endothelium, due in part to the ability of linoleic acid (18:2n-6) to contribute to an increase in cellular oxidative stress and related injurious events. Exposing endothelial cells to 90 micromol linoleic acid/L for 6 h resulted in a significant increase in lipid hydroperoxides that coincided wih an increase in intracellular calcium concentrations. Treatment with this fatty acid caused an initial decrease in glutathione concentrations, which was followed by an increase at later time points. Most importantly, a significant activation of the oxidative stress-sensitive nuclear transcription factor-kappa B (NF-kappa B) was achieved after a 6-h exposure to 18:2n-6, which is the time point at which maximal depletion of cellular glutathione was observed. The fatty acid-mediated NF-kappa B activation was accompanied by induction of NF-kappa B-dependent transcription, as measured by chloramphenicol acetyltransferase (CAT) assay of an NF-kappa B-responsive promoter construct. Pretreatment of endothelial cells with vitamin E and N-acetyl cysteine inhibited the fatty acid-induced activation of NF-kappa B and formation of lipid hydroperoxides. These data suggest that oxidative stress-induced cellular changes are critical early events in fatty acid-mediated endothelial cell dysfunction.

A high dose of ionizing radiation induces tissue-specific activation of nuclear factor-kappaB in vivo.

Activation of the transcription factor nuclear factor-kappaB (NF-kappaB) is one of the important responses of cells to an external stress such as ionizing radiation. We studied radiation-induced NF-kappaB activation in vivo in male BALB/c mice. After the mice were exposed to 8.5 Gy total-body gamma irradiation, the spleen, mesenteric lymph nodes, thymus, liver, lung, colon, brain and bone marrow were harvested 1, 2.5, 5, 10 and 20 h postirradiation. NF-kappaB DNA-binding activity was analyzed in the nuclear protein extracts by a gel shift assay. When compared to the levels in untreated control mice, radiation induced activation of NF-kappaB in spleen, mesenteric lymph nodes and bone marrow but not in the other tissues examined. In contrast, an i.p. injection of a lethal dose (3 mg/kg) of lipopolysaccharide also increased activity of NF-kappaB in the liver and lung. The gel supershift assay with Nfkb1, Rela and/or Rel antibodies revealed that the specific molecular forms of NF-kappaB activated by radiation in the spleen were Nfkb1 homodimers and Nfkb1/Rela heterodimers. In mesenteric lymph nodes, the heterodimerized Rel/Rela NF-kappaB was also activated. In bone marrow, an NF-kappaB-like binding factor was induced that may be Nfkb1/Rela- and Rel/Rela-like heterodimers, but it exhibited a higher mobility than Nfkb1 homodimers. These results indicate that in vivo, ionizing radiation induces NF-kappaB activation that varies in both tissue distribution and moleoular composition.

Antioxidants attenuate nuclear factor-kappa B activation and tumor necrosis factor-alpha production in alcoholic hepatitis patient monocytes and rat Kupffer cells, in vitro.

UNLABELLED: There is increased tumor necrosis factor-alpha (TNF) activity in alcoholic hepatitis (AH). OBJECTIVES: To examine the effects of antioxidants and glutathione enhancing agents on NF-kappaB activation and TNF production in Kupffer cells and monocytes. DESIGN AND METHODS: Isolated rat Kupffer cells and peripheral blood monocytes from AH patients were treated in vitro. NF-kappaB activation was assessed by electrophoretic mobility shift assay and TNF was measured in cell culture supernatants. RESULTS: Monocytes from AH patients had greater TNF production compared to normal volunteers. Pretreatment with antioxidants or gluathione enhancing agents inhibited TNF production and NF-kappaB activation in both monocytes from normal and AH patients as well as in rat Kupffer cells. CONCLUSIONS: There may be a therapeutic role for antioxidants or glutathione enhancing agents in disease states with increased TNF activity such as AH.

Cytokines and alcoholic liver disease.

Chemical messengers called cytokines play an important role during the body's initial response to infection (i.e., acute inflammation). Cytokines attract and activate components of the immune system, promote blood clotting, and facilitate the release of additional chemical messengers. In addition, cytokines induce the liver to shift its physiological function, emphasizing inflammatory and immune responses at the expense of normal metabolism. Alcohol consumption may cause excessive cytokine production in the liver, leading to inflammatory liver disease. Researchers are seeking ways to moderate the toxic effects of cytokines while sparing their protective functions.

Biotypes of Gardnerella vaginalis isolated from non-specific vaginitis patients in Bombay.

The incidence and prevalent biotypes of G. vaginalis in patients with non-specific vaginitis from Bombay, was studied. Of 300 patients screened, 105 were diagnosed to have nonspecific vaginitis (NSV). G. vaginalis was isolated from 71 per cent patients with NSV; 34.6 and 29.3 per cent G. vaginalis were belonging to biotypes 5 and 1 respectively. In 55 per cent patient, G. vaginalis was associated with anaerobes. None of the isolated strains of G. vaginalis was sensitive to 5 micrograms metronidazole disc whereas 93 per cent of the strains were sensitive to 50 micrograms metronidazole disc.

Early predictors of neurodevelopmental outcome in high risk infants.

OBJECTIVE: To find out a few simple and easily elicitable items at three and six months of age that can predict neurodevelopmental outcome at one year in high risk babies. DESIGN: One year longitudinal follow up study. SETTING: Hospital based study including inborn and outborn infants discharged from the Neonatal Intensive Care Unit (NICU) of a referral hospital, followed up in a High Risk Clinic. METHODS: Sixty high risk babies were followed up longitudinally for a period of one year. A detailed neurodevelopmental examination was done with special attention to the following items-axillary suspension, head support, social smile, disappearance of primitive reflexes and neurobehavior at three months age while pull to sit, rolling over, sitting momentarily without support, transfer of objects and voluntary reach were evaluated at six months age. Bayley Scales of Infant Development (Baroda Norms) was used for assessing the outcome at one year. RESULTS: Babies with absence of social smile, abnormal neurobehavior at three months and absent pulling to sit position, absent voluntary reach, and absent transfer of objects, remained delayed at one year. The specificity of each of these items was 100%. These items had a positive predictive value of 100%. CONCLUSIONS: Inability to achieve social smile and abnormal neurobehavior at three months age and absence of pulling to sit position, transfer of objects and voluntary reach at six months age, warrant early intervention. These items are easy to elicit, do not require any special kit or elaborate training. Hence these items can be tested even by those working at the primary level or in office practice.

Neurologic sequelae in high risk infants--a three year follow up.

OBJECTIVE: To determine the neurologic sequelae in high risk infants. DESIGN: A three year longitudinal follow up. SETTING: Inborn and outborn infants discharged from the Neonatal Special Care Unit (NSCU) of a referral hospital. METHODS: High risk infants were identified for follow up using predetermined risk criteria. A detailed neurodevelopmental examination was done 3 monthly in the first year and 6 monthly subsequently. The Amiel-Tison Method, Bayley Scales of Infant Development and Raval's Scale for social maturity were used. EEG was done in children with seizures. Hearing and ophthalmic assessments were done at 6 months. RESULTS: Three hundred and thirty six high risk infants and 70 normal control infants came for regular follow up. Out of these, 16 (4.8%) had cerebral palsy and 11 had associated mental retardation. Six other children had mental retardation without motor problems. None of the children in the control group had any neurological problems. Sensorineural hearing loss was present in 5 (1.5%) children while 1 subject had corfical blindness. Three children with cerebral palsy had infantile myoclonus, nine had generalized seizures and one child had a focal seizure. The incidence of seizure disorders was 3.9%. CONCLUSIONS: The incidence of major handicap in our study was low. Many of the risk factors which caused adverse outcome, could have been prevented by good antenatal and perinatal care.

A longitudinal follow up of neurodevelopment of high risk newborns--a comparison of Amiel-Tison's method with Bayley Scales of Infant Development.

The neurodevelopment of 42 high risk babies and 7 control babies was assessed longitudinally till the age of 12 months by using two different methods. The method of neurological evaluation described by Amiel-Tison was used, and the results compared with those of a standard developmental test, the Bayley Scales of Infant Development. The Amiel-Tison method was found to be a sensitive test for picking up abnormalities till the age of 9 months, but lost its advantage over the Bayley Scales at 12 months. Besides, the test was quick, simple to learn and did not need a special kit or a trained psychologist and was hence found to be a good screening method.

lcrR, a low-Ca2(+)-response locus with dual Ca2(+)-dependent functions in Yersinia pestis.

The low-Ca2+ response (Lcr) of Yersinia includes a regulatory cascade and a set of virulence-related proteins, one of which is the V antigen. The regulatory genes modulate both bacterial growth and expression of the virulence-related proteins in response to temperature and the presence of Ca2+ and nucleotides. In this study we defined a new Lcr locus, lcrR, in Yersinia pestis KIM. An lcrR mutant, obtained by insertion mutagenesis, failed to grow at 37 degrees C whether Ca2+ was present or not. However, it grew normally in the presence of ATP, showing that the Ca2(+)- and nucleotide-responsive mechanisms are separate in Y. pestis. The lcrR mutant was avirulent in mice, probably due to its compromised growth at 37 degrees C. beta-Galactosidase measurements and Northern (RNA blot) analysis revealed that lcrR transcription was regulated primarily by temperature. The DNA sequence of the lcrR locus contained a single open reading frame of 441 bases that could encode a protein with a molecular weight of 16,470 and a pI of 10.73. Expression of an lcrR-containing clone in Escherichia coli yielded a 16,000-molecular-weight protein. At 37 degrees C, the lcrR mutant strongly expressed V antigen and initiated lcrGVH transcription whether Ca2+ was present or not, indicating that this mutant had lost the transcriptional downregulation of lcrGVH shown by the parent in the presence of Ca2+. In the absence of Ca2+, the mutant failed to express LcrG, even though lcrGVH mRNA initiated upstream of lcrG at the normal sites. These data suggest that the lcrR locus is necessary for the regulation of LcrG expression in the absence of Ca2+. Therefore, this locus has a dual regulatory role in the low-Ca2+ response.

Comparative Effect of Concentration of Carbohydrate and Salt on Detection of Thermonuclease and Coagulase in Pathogenic Strains of Staphylococcus aureus.

In a study on nine pathogenic strains of Staphylococcus aureus , it was observed that detection of thermonuclease in these strains was not influenced by the level of glucose, mannitol or salt in the BHI broth medium. However, free coagulase was influenced by these additions.

Tumor necrosis factor and alcoholic liver disease.

Increased levels of hepatic and serum tumor necrosis factor (TNF) have been documented in animal models of alcoholic liver disease and in human alcoholic liver disease. This dysregulated TNF metabolism has been postulated to play a role in many of the metabolic complications and the liver injury of alcoholic liver disease. One potential therapy for alcoholic liver disease may be agents that downregulate TNF production or block TNF activity. Indeed, agents such as prostaglandins and glucocorticoids (both inhibit TNF production) have been used in both human liver disease and experimental models of liver injury, and anti-TNF antibody has recently been shown to attenuate the hepatotoxicity in an animal model of alcoholic-related liver disease. In this study, we demonstrate that a simple ex vivo system can be used to initially assess potential efficacy of anticytokine agents when administered to humans. Both prednisone and a prostaglandin analog were effective in downregulating TNF and interleukin-8 production. The liver is normally resistant to TNF cytotoxicity. Sensitivity to TNF cytotoxicity is thought to occur when there is inadequate production of hepatic protective factors. In this study, we showed that, when patients with acute alcoholic hepatitis were matched with trauma patients for serum levels of interleukin-6, they had similar depressions in the negative acute phase protein, albumin, but markedly different increases in the major acute phase protein, C reactive protein. Patients with alcoholic hepatitis had a very blunted response. We also showed that inhibiting activation of the redox sensitive transcription factor NFkappaB sensitizes to TNF-induced hepatocyte death in vitro. This transcription factor is important for the production of both cytokines and many acute phase protective factors. Several hepatic protective factors are induced by TNF. One possible mechanism for liver injury in alcoholic hepatitis may be inadequate generation of hepatic protective factors. Our future understanding of mechanisms of alcoholic liver disease will involve understanding the balance between noxious and protective factors in the liver, and this should lead to rational therapy for this disease process.