Sodium ion influences on phosphorylations associated with oxidation of succinate by turnip root mitochondria.

Sodium ions (10(-3) mole/liter) cause a marked increase in the ratio of phosphate esterified to oxygen utilized when turnip root mitochondria oxidize succinate. Separate study of the two phosphorylation sites associated with succinate oxidation indicates that the observed effect is a summation of differential responses of these sites to sodium ions. The activity of the first site, that associated with the reduction of cytochrome c, is stimulated about threefold by 10(-3) molar NaCl, whereas phosphorylation at the second site, coupled with the oxidation of ferrocytochrome c, is slightly inhibited by the same concentration of NaCl.

Prevalence and Association of Obesity with Self-Reported Comorbidity: A Cross-Sectional Study of 1321 Adult Participants in Lasbela, Balochistan.

Association of fatness with chronic metabolic diseases is a well-established fact, and a high prevalence of risk factors for these disorders has increasingly been reported in the third world. In order to incorporate any preventive strategies for such risk factors into clinical practice, decision-makers require objective evidence about the associated burden of disease. A cross-sectional study of 1321 adults from one of the districts of Balochistan, among the most economically challenged areas of Pakistan, was carried out for the measures of fatness and self-reported comorbidities. Body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR) were measured and demographic information and self-reported comorbidities were documented. The prevalence of obesity was 4.8% (95% CI: [3.8, 6.1]) and 21.7% (95% CI: [19.5, 24.0]), as defined by the World Health Organization (WHO) international and Asia/Asia-Pacific BMI cut-offs, respectively. The proportion exhibiting comorbidity increased with increasing levels of fatness in a dose-response relationship (p value < .001). An interaction of weight status with gender was observed to produce a significantly (p = .033) higher comorbidity among overweight women (odds ratio (OR) = 6.1 [1.2, 31.7]) compared with overweight men (OR = 1.1 [0.48, 2.75], p = .762).

The effect of mycobacterial virulence and viability on MAP kinase signalling and TNF alpha production by human monocytes.

SETTING: The success of Mycobacterium tuberculosis as a human pathogen depends on its ability to tolerate and perhaps manipulate host defense mechanisms. OBJECTIVE: To determine the induction of tumour necrosis factor-alpha (TNF alpha), a central mediator of immunity, by human monocytes infected with virulent M. tuberculosis, M. leprae and attenuated M. bovis BCG. DESIGN: Mycobacteria-induced cellular activation pathways of TNF alpha production was investigated using an inhibitor of protein tyrosine kinase (PTKs) and an inhibitor of mitogen-activated protein (MAP) kinases. RESULTS: TNF alpha production was significantly lower during infection with virulent M. tuberculosis than with BCG and this differential response was independent of mycobacterial viability. TNF alpha production involved the PTK and MAP kinase pathways. Reduced TNF alpha induction by M. tuberculosis was associated with a reduction in the extent and duration of phosphorylation of extracellular-signal regulated kinases (ERK 1/2). Infection with M. leprae triggered low and transient ERK 1/2 activation as well as low TNF alpha production. CONCLUSION: Maintenance of the differential response in both live and heat-killed preparations suggests that the reduced TNF alpha response associated with virulent mycobacteria is due to differences in the presence of components capable of triggering host pattern recognition receptors, rather than events associated with phagosome trafficking or the active release of intracellular modulators.

The inhibitory effect of cinchonine on human platelet aggregation due to blockade of calcium influx.

The Cinchona bark contains alkaloids like quinine, quinidine, cinchonine and cinchonidine. These agents are effective antimalarial drugs and have been used clinically in malaria caused by Plasmodium falciparum. Previous studies show that quinine and quinidine exert effects on cardiovascular system. This study was conducted to examine the effect of cinchonine on human platelet aggregation. The results show that cinchonine inhibited platelet aggregation mediated by platelet agonists, epinephrine (200 microM), ADP (4.3 microM), platelet activating factor (PAF; 800 nM) and collagen (638 nM) but had no effect on arachidonic acid (AA; 0.75 mM). Cinchonine was most effective in inhibiting aggregation induced by platelet activating factor and epinephrine with IC50 values of 125 and 180 microM respectively, however, higher concentrations of cinchonine were required to inhibit aggregation mediated by ADP or collagen (IC50; 300 microM). Pretreatment of platelets with cinchonine inhibited aggregation caused by Ca2+ ionophore, A-23187 (6 microM), in a dose-dependent manner (IC50; 300 microM) indicating an inhibitory effect on Ca2+-signaling cascade. This was supported by measuring [Ca2+]i in platelets loaded with Fura-2AM where cinchonine inhibited the rise in cytosolic Ca2+ mediated by A-23187 (6 microM) or collagen (638 nM). Results show that cinchonine (20 microM) also inhibited aggregation when platelets were pretreated with protein kinase C (PKC) activator, phorbol myristate acetate (PMA; 0.1 microM) in combination with low doses of platelet activating factor (80 nM). Cinchonine, however, had no effect on AA-induced platelet aggregation and thromboxane A2 (TXA2) synthesis in platelets. These results suggest that antiplatelet effects of cinchonine are mediated mainly through inhibition of Ca2+-influx and protein kinase C pathways in platelets.

Inhibitory effect of curcumin, a food spice from turmeric, on platelet-activating factor- and arachidonic acid-mediated platelet aggregation through inhibition of thromboxane formation and Ca2+ signaling.

Curcumin, a dietary spice from turmeric, is known to be anti-inflammatory, anticarcinogenic, and antithrombotic. Here, we studied the mechanism of the antiplatelet action of curcumin. We show that curcumin inhibited platelet aggregation mediated by the platelet agonists epinephrine (200 microM), ADP (4 microM), platelet-activating factor (PAF; 800 nM), collagen (20 microg/mL), and arachidonic acid (AA: 0.75 mM). Curcumin preferentially inhibited PAF- and AA-induced aggregation (IC50; 25-20 microM), whereas much higher concentrations of curcumin were required to inhibit aggregation induced by other platelet agonists. Pretreatment of platelets with curcumin resulted in inhibition of platelet aggregation induced by calcium ionophore A-23187 (IC50; 100 microM), but curcumin up to 250 microM had no inhibitory effect on aggregation induced by the protein kinase C (PKC) activator phorbol myrsitate acetate (1 microM). Curcumin (100 microM) inhibited the A-23187-induced mobilization of intracellular Ca2+ as determined by using fura-2 acetoxymethyl ester. Curcumin also inhibited the formation of thromboxane A2 (TXA2) by platelets (IC50; 70 microM). These results suggest that the curcumin-mediated preferential inhibition of PAF- and AA-induced platelet aggregation involves inhibitory effects on TXA2 synthesis and Ca2+ signaling, but without the involvement of PKC.

Cholera toxin mediated regulation of the expression of Gq alpha and G11 alpha GTP binding proteins.

Previously it has been shown that persistent activation of the stimulatory adenylyl cyclase pathway with cholera toxin (CT) downregulates the Gs alpha polypeptide (80%) in a cAMP-independent manner in C6 glioma cells (Shah, 1997). This study was conducted to examine the short and long term effects of CT on the regulation of pertussis toxin-sensitive and -insensitive G proteins and their transcripts in C6 glioma cells. Treatment of C6 cells with CT (100 ng/ml) up to 16 h had no effect on either Gi or Gq/11 alpha proteins. However, prolonged exposure (24-48 h) caused increased expression of Gi (20-30%) and Gq/11 alpha proteins (40%). Urea gradient gels, which can separate Gq alpha and G11 alpha proteins, revealed that prolonged CT treatment increased the expression of both of these G proteins. The CT-mediated enhanced expression of Gq alpha and G11 alpha proteins was accompanied by increased mRNA levels of these proteins as determined by RT/PCR. Cyclic-AMP elevating agents like forskolin (10 microM) and db-cAMP (1 mM) mimicked the effect of CT on Gi but not Gq/11 alpha proteins. These studies show long term cAMP-dependent regulation of Gi and cAMP-independent expression of Gq/11 alpha proteins in C6 glioma cells.

Co-activation of Gi and Gq proteins exerts synergistic effect on human platelet aggregation through activation of phospholipase C and Ca2+ signalling pathways.

Our previous studies have shown that subthreshold concentrations of two platelet agonists exert synergistic effects on platelet aggregation. Here we studied the mechanism of synergistic interaction of 5-hydroxytryptamine (5-HT) and epinephrine mediated platelet aggregation. We show that 5-HT had no or little effect on aggregation but it did potentiate the aggregation response of epinephrine. The synergistic interaction of 5-HT (1-5 microM) and epinephrine (0.5-2 microM) was inhibited by alpha2-adrenoceptor blocker (yohimbine; IC50= 0.4 microM), calcium channel blockers (verapamil and diltiazem with IC50 of 10 and 48 mM, respectively), PLC inhibitor (U73122; IC50=6 microM) and nitric oxide (NO) donor, SNAP (IC50=1.6 microM)). The data suggest that synergistic effects of platelet agonists are receptor-mediated and occur through multiple signalling pathways including the activation PLC/Ca2+ signalling cascades.

Molecular mechanisms involved in human platelet aggregation by synergistic interaction of platelet-activating factor and 5-hydroxytryptamine.

Our recent studies have shown that co-activation of Gq and Gi proteins by 5-hydroxytryptamine (5-HT) and adrenaline show synergism in human platelet aggregation. This study was conducted to examine the mechanism(s) of synergistic interaction of 5-HT and platelet activating factor (PAF) in human platelets. We show that PAF, but not 5-HT, increased platelet aggregation in a concentration-dependent manner. However, low concentrations of 5-HT (2 microM) potentiated platelet aggregation induced by subthreshold concentration of PAF (40 nM) indicating a synergistic interaction between the two agonists and this synergism was blocked by receptor antagonists to either 5-HT or PAF. 5-HT also potentiated the effect of PAF on thromboxane A2 (TXA2) formation and phosphorylation of extracellularly regulated mitogen-activated protein kinases (ERK1/2). The synergism of 5-HT and PAF in platelet aggregation was inhibited by calcium (Ca2+) channel blockers, verapamil and diltiazem, phospholipase C (PLC) inhibitor, U73122, cyclooxygenase (COX) inhibitor, indomethacin, and MEK inhibitor, PD98059. These data suggest that synergistic effect of 5-HT and PAF on human platelet aggregation involves activation of PLC/Ca2+, COX and MAP kinase pathways.

Role of the cell recognition molecule, cognin, in GABAergic differentiation in chick retina.

Previous work showed that GABAergic differentiation in developing chick retina depends on insulin and cell interactions. Here, we investigated whether it depended on cell signaling mediated by retina cognin, a 50 kDa cell recognition molecule. Cognin mediates cell adhesion in vitro and occurs on retinal neurons that become both GABAergic and cholinergic. We investigated two markers of GABAergic differentiation: glutamate decarboxylase (GAD) activity and high-affinity GABA uptake. Both increase during differentiation of retinal neurons in culture and can be easily measured. We blocked cognin-mediated cell signaling with cognin antibody and found a reduction of the developmental increase in GAD activity in cultures of retinal neurons from 7 and 11 day chick embryos. There was no reduction of high-affinity GABA uptake. This suggested that cognin-mediated signaling was necessary for the normal developmental increase in GAD but not for high-affinity GABA uptake. These results contrasted with our previous observations on cholinergic differentiation in cultured retinal neurons. We found that cognin antibody blocked the normal developmental increase in choline acetyltransferase (ChAT) only if the cells were exposed before embryonic day 7. Thus, while both GAD and ChAT activity appear to be controlled by cell signaling involving cognin, the periods of developmental sensitivity for the two differentiation markers are different. Antibodies to other adhesion molecules, Ng-CAM, and N-cadherin, did not similarly affect GAD activity. Antibodies to laminin at a 10-fold higher concentration inhibited GAD activity only in early embryonic retina. Tests for protein synthesis and "housekeeping" enzyme activity demonstrated that the cognin antibody effect was selective for neuronal differentiation pathways.(ABSTRACT TRUNCATED AT 250 WORDS)

Neonatal androgen manipulation differentially affects the development of monoamine systems in rat cerebral cortex, amygdala and hypothalamus.

Neural tissue during perinatal life is sufficiently plastic to respond to the presence of testicular androgens. Here we studied the effect of neonatal androgen manipulation (castration of male and androgenization of female rats) on monoamine neurotransmitter systems in the cerebral cortex and sexually dimorphic regions of brain (hypothalamus and amygdala). Norepinephrine (NE) and dopamine (DA) concentrations in cortex, amygdala and hypothalamus of rats were assayed by HPLC at days 25, 60, 120, 180, 240 and 300. Results show that NE levels in all groups of rats at day 25 were higher in the hypothalamus (5-9 ng/mg protein) compared to the amygdala (0.5-3 ng/mg protein) and the cortex (0.5-1 ng/mg protein). Levels of DA at day 25 in the hypothalamus and the amygdala were comparable (up to 3.5 ng/mg) but higher than in the cortex (1.25-1.75 ng/mg protein). NE and DA concentrations in sham-castrated male and androgen-treated females were higher at day 25 compared to castrated male and control females in both amygdala and hypothalamus; however, levels of NE and DA remained unchanged in the cortex. Pattern of NE concentrations started reversing with increase in age, i.e., NE levels in control females and castrated males increased almost 4-fold in amygdala and 2-fold in hypothalamus by day 300, but there was no significant change in the cortex. Compared to that, NE levels decreased in sham-castrated male (2-fold) and androgen-treated females (3-fold) in amygdala as well as in the hypothalamus (2-fold) in both these groups. A similar pattern of reversal of DA levels was found in both amygdala and hypothalamus, however, at day 300 DA levels were comparable in all the four groups. These studies suggest that androgen manipulation (castration or androgen administration) induces age-dependent short- and long-term effects on the development of noradrenergic and dopaminergic systems in the sexually dimorphic regions of brain, amygdala and hypothalamus, without a significant change in the cerebral cortex.

Effect of insulin on GABAergic development in the embryonic chick retina.

We investigated the role of insulin in GABAergic differentiation in the embryonic chick retina at different embryonic ages using glutamate decarboxylase (GAD) and high-affinity GABA uptake as developmental markers. Both these GABAergic markers exhibit developmentally programmed increases in activity during retinogenesis that also occur in culture. Insulin stimulated GABA uptake in retina neurons at all embryonic ages in a dose-dependent manner and GAD activity by 30% in embryonic retina neurons after 11 days of development. The stimulation of GABA uptake by insulin was blocked by addition of ouabain suggesting a role for the Na+,K+ ATPase. The same concentration of insulin caused a 76% stimulation of protein synthesis in these retinal cells, and previous work demonstrated that insulin also stimulates cholinergic differentiation in the chick retina (Hausman et al., Dev. Brain. Res. 59, (1991) 31-37). Thus, there was no selective stimulation of GABAergic differentiation by insulin but likely a neurotrophic effect. The increase in GAD activity in neurons from post-11-day embryonic neurons contrasts with our previous findings at embryonic days 6-7 where there is little change in GAD activity after addition of insulin. It is possible that the failure of insulin to stimulate GAD activity during early retina development is due to the increased accumulation of GABA in the presence of insulin. GABA levels were increased more than two-fold by 100 ng/ml insulin.

Initial cholinergic differentiation in embryonic chick retina is responsive to insulin and cell-cell interactions.

Previous work [Kyriakis et al., Proc. Natl. Acad. Sci. U.S.A., 84 (1987) 7463-7467] had shown that insulin, when added during a window of binding from embryonic days 9-11, stimulates the normal developmental increase in choline acetyltransferase (ChAT) activity (a marker for cholinergic differentiation) in cultured embryonic chick retinal neurons. Here, we investigated the effect of insulin and IGF 1 on embryonic chick retinal neurons at the stage of development (embryonic day 6) when ChAT activity is first expressed. We investigated insulin peptide effects in retinal tissue developing in vitro as well as in cultures of retinal cells. We show that insulin also stimulated the initial embryonic increase in ChAT activity but had no stimulatory effect on glutamic acid decarboxylase activity (a marker for GABAergic differentiation), an enzyme whose activity also increases developmentally in the same retinal neurons. In fact, insulin inhibited the expression of GAD activity in the retina. The insulin-mediated increase in ChAT activity was independent of normal cell-cell interactions but could not replace them. Insulin also stimulated choline uptake but only after a two day delay, suggesting that the normal program for cholinergic differentiation in the chick retina was induced by insulin. IGF 1 did not have any effect on either cholinergic or GABAergic differentiation. We conclude that cholinergic differentiation in chick embryo retinal neurons is dependent on both insulin- and cell contact-mediated signals.

Dual effects of nimesulide, a COX-2 inhibitor, in human platelets.

Nimesulide (CAS 51803-78-2) has been shown to exert marked anti-inflammatory effect in several in vivo models of inflammation. Since nimesulide is considered to be a selective inhibitor of COX-2, it has not been studied in detail in relation to its mechanistic effects on platelets, which express COX-1. This study was conducted to investigate the effects of nimesulide in platelet aggregation. We show that nimesulide (1-100 microM) inhibited platelet aggregation induced by adrenaline (20-200 microM). It also inhibited thromboxane A2 (TXA2) formation by platelets at low concentration (IC50; 1 microM). However, much lower concentrations of nimesulide (0.01-0.1 microM) potentiated the aggregatory response of subthreshold concentrations of adrenaline (0.2-2 microM). Such an effect was blocked by Ca2+-channel blockers, verapamil and diltiazem (IC50: 7 and 46 microM, respectively), nitric oxide donor, SNAP (IC50; 2 microM) and cinchonine (10 nM) but not by genistein (up to 10 microM). These results are indicative of the concentration-dependent dual effects of nimesulide on human platelet aggregation. The synergistic effect of low doses of nimesulide and adrenaline seems to be mediated through inhibition of multiple signalling pathways.

Perinatal exposure to morphine disrupts brain norepinephrine, ovarian cyclicity, and sexual receptivity in rats.

The effect of perinatal exposure to morphine on the development of catecholaminergic and reproductive function in female rats was investigated. Adult rats received morphine intraperitoneally daily for 40 days. The dose of morphine was progressively increased at 10-day intervals from 5, 7.5, 10 to 15 mg/kg body weight until day 40. The rats were mated between days 38 and 45. Administration of morphine at dose rates of 20 and 30 mg/kg continued during pregnancy. The dose was increased to 40 mg/kg for 10 days postpartum. Results showed that morphine disrupted ovarian cyclicity in 52% of the females. Amongst the remaining females, 43% became pregnant when mated. In the female offspring born to such dams, sexual maturation was delayed and body weight was reduced until weaning. At adulthood, lordosis behavior was inhibited when the female offspring were tested against stimulus males. Plasma estradiol and ovarian estradiol and progesterone levels were reduced. Norepinephrine concentration in the hypothalamus was reduced, whereas it remained unchanged in the amygdala. Dopamine concentrations in both hypothalamus and amygdala were not influenced by perinatal morphine exposure. These results suggest that chronic morphine treatment during perinatal life selectively influences the development of noradrenergic mechanisms in the rat brain and this may in turn be responsible for reduced reproductive activity.

Enhanced degradation of stimulatory G-protein (Gs alpha) by cholera toxin is mediated by ADP-ribosylation of Gs alpha protein but not by increased cyclic AMP levels.

Cholera toxin (CT) catalyses ADP-ribosylation of the alpha-subunit of stimulatory protein (Gs) leading to stimulation of adenylyl cyclase and elevated intracellular cAMP. Persistent treatment (24-48 h) of C6 glioma cells with cholera toxin (100 ng/ml) caused marked downregulation of Gs alpha (75-80%) which could not be mimicked by dibutyryl cAMP (1 mM) and forskolin (10 microM) over the same time periods suggesting that CT-mediated Gs alpha downregulation is independent of cAMP production. However, CT increased the expression of Gq/11 alpha proteins at 24 and 48 h of treatment. The increase in mRNA levels of Gq/11 alpha proteins preceded the increase in Gq/11 proteins. Such stimulatory effects of CT were mimicked by forskolin and dibutyryl-cAMP. These results suggest that CT-mediated downregulation of Gs alpha is independent of cAMP but CT upregulates the expression of Gq/11 alpha proteins in a cAMP-dependent manner.

Renal clearance of endogenous creatinine and urea in sheep during summer and winter.

Simultaneous measurement of the renal clearance of endogenous creatinine and exogenous inulin in eight sheep showed similar mean +/- SD (n = 32) values of 13.8 +/- 1.3 and 13.2 +/- 2.0 ml min-1 (10 kg)-1 bodyweight respectively. These results demonstrate that the renal clearance of endogenous creatinine is a satisfactory measure of glomerular filtration rate (GFR) in sheep. The plasma concentrations of endogenous creatinine and urea were significantly higher because of haemoconcentration during summer, resulting in lower GFR than in winter. Besides glomerular filtration and back diffusion, the renal handling of urea in sheep seems to involve mechanisms analogous to active tubular secretion.

Tetanus in a case of lepromatous leprosy.

A patient of Lepromatous Leprosy had neuropathic plantar ulcer of 6 months duration. He developed "Tetanus". We are reporting this case with review of literature, as there is dearth of published literature on this association of Leprosy and Tetanus.

Flu like syndrome with rifampicin pulse therapy.

Flu like syndrome was found in a patient of BT leprosy taking Rifampicin in pulse therapy. This side effect was absent when the dose of Rifampicin was decreased. Details of this case is given with a review of literature.

A clinical study of eye complications in leprosy.

A study was conducted to find out the incidence of ocular complications in leprosy. The ocular lesions were found in 6.6% of lepromatous leprosy and 1.6% in nonlepromatous leprosy. Out of 150 patients with eye lesions 74% were males and 80% belonged to lepromatous leprosy. The age group in all the patients varied from 3rd to 6th decade. Mean duration of leprosy ln lepromatous leprosy was 6.2 years. The important eye complication observed were lagophthalmos (8.1%), corneal ulcers (10%) and iridocyclitis (24%). The loss of eye-brows (76%) was found to be most frequent in this study followed by corneal lesion (62%). It is concluded that examination of eyes are essential in all types of leprosy.

Effect of chronic administration of aspirin, phenobarbitone and oxytetracycline on the plasma levels of vitamin A in albino rats.

Effect of chronic administration of aspirin, phenobarbitone and oxytetracycline under therapeutic doses on the bioavailability of vitamin A was determined in different groups of albino rats. The rats treated with phenobarbitone (group C) showed significantly decreased vitamin A level in plasma whereas the other two groups (B and D) treated with aspirin and oxytetracycline respectively did not exhibit any significant difference as compared to control group (A).