Temporal evolution of electron cloud in a cylindrical Penning trap at room temperature

The temporal evolution of the electron cloud at room temperature has been recorded through a resonance circuit by observing the axial oscillation frequency of its center of mass. The electron cloud undergoes radial expansion by interacting with the residual gas molecules, and it is finally lost upon hitting the Penning trap electrodes. It has been confirmed through detailed experimental investigations that the unique temporal pattern of frequency variation is a consequence of the cloud's radial expansion. Consequently, this approach offers a non-destructive means for single-shot detection, enabling continuous monitoring of the electron cloud's radial expansion during the confinement time. This technique offers a significant advantage over its destructive alternatives.

Design of a helical resonator with improved figure of merit

A helical resonator serves as a key element for the detection of the trapped charged particles in a Penning trap. In order to compare the performance of the helical resonators, the concept of figure of merit (FOM) was introduced by Ulmer et al. [Nucl. Instrum. Methods Phys. Res., Sect. A 705, 55-60 (2013)]. In this work, we optimized the geometrical parameters of a resonator by numerical simulations keeping its outer dimensions and the diameter of the copper wire fixed and obtained the best possible value of FOM under these constraints. The corresponding 95 MHz helical resonator has been designed and fabricated, and its measured value of FOM is in good agreement with the simulated values. An empirical relationship between the total length of the wire to make the helical coil and the resonance frequency has been obtained. The simulations show that the FOM increases considerably with the increase in the conductivity of the building material, and this would be useful in detecting the feeble trap signal in cryogenic environment.

Fabrication of non-magnetic multi-pin coaxial vacuum feedthrough system for cryogenic applications

We have developed and tested a compact non-magnetic feedthrough made of epoxy resin and capable of maintaining vacuum leak tightness over a wide temperature range (300 K-4 K). It is equipped with 15 electrical pins and three 50 Ω coaxial lines. The feedthrough has been designed to apply a high voltage (up to 5 kV) and transmit radio-frequency signals for operating a Penning trap over a wide temperature range (300 K-4 K). The characteristic impedances of the coaxial lines have been measured at 300 K and 77 K and found to remain ∼50 Ω over the frequency range of our interest (10 MHz-80 MHz). The details of its fabrication and performance over a wide temperature range have been discussed.

Hyperbaric oxygenation ameliorates indomethacin-induced enteropathy in rats by modulating TNF-alpha and IL-1beta production

The effect of hyperbaric oxygenation (HBO2) was investigated in a rat model of indomethacin-induced enteropathy. Enteropathy was induced by two subcutaneous injections of indomethacin (7.5 mg/kg) 24 hr apart. Six groups of rats (n=8) were treated with and without HBO2 (100% oxygen at 2.3 atm absolute) for 1 hr once or twice a day for 2 or 5 days. Disease activity index (DAI) and total ulcer length were measured. Other rats were randomized into two groups (n=16) with and without HBO2 (1 hr once a day) and four rats were killed in each group at 12, 24, 48, and 72 hr after the final injection of indomethacin. Serum and intestinal mucosal TNF-alpha, IL-1beta, myeloperoxidase (MPO), and iNOS expression was measured. HBO2 treatment significantly attenuated indomethacin -induced intestinal ulceration and improved DAI. Indomethacin increased MPO activity and iNOS expression, and these were reduced by HBO2 treatment, with a concomitant reduction in TNF-alpha and IL-1beta. Our data suggest that HBO2 treatment has a beneficial effect on indomethacin-induced enteropathy and this effect is possibly mediated by decreased production of TNF-alpha and IL-1beta.

Inhibition of TNF-alpha improves indomethacin-induced enteropathy in rats by modulating iNOS expression

TNF-alpha, including other proinflammatory cytokines alone or in combination, induces iNOS expression and upregulates inflammatory responses. We evaluated the relationship between TNF-alpha and iNOS expression in indomethacin-induced jejunoileitis in male Sprague-Dawley rats. Rats were fed a daily dose of a phosphodiesterase inhibitor-either theophylline or pentoxifylline-for 2 days. Jejunoileitis was induced with two subcutaneous injections of indomethacin (7.5 mg/kg) 24 hr apart and theophylline or pentoxifylline continued for 12 hr or 4 days. Other rats received a single intraperitoneal injection of anti-TNF-alpha monoclonal antibody (TNF-Ab) 30-min before indomethacin. At 4 days TNF-Ab, theophylline, or pentoxifylline treatment significantly decreased indomethacin-induced ulceration, myeloperoxidase activity, and disease activity index. Although indomethacin significantly increased serum TNF-alpha and nitrate/nitrite levels over the control value as early as 12 hr, iNOS expression was detected only after 4 days. Serum IL-1beta level did not change at 12 hr but increased fourfold at 4 days. Treatment with TNF-Ab, theophylline, or pentoxifylline significantly reduced serum/tissue TNF-alpha, IL-1beta, nitrate/nitrite, and iNOS expression. The downregulation of nitrate/nitrite by these inhibitors suggests that TNF-alpha modulates iNOS expression.

Nitric oxide inhibitors ameliorate indomethacin-induced enteropathy in rats

The role of nitric oxide (NO) synthase inhibitors in indomethacin (INDO) -induced enteropathy was investigated in male Sprague-Dawley rats. Rats were subcutaneously administered 5% sodium bicarbonate (controls), two doses of INDO 7.5 mg/kg, and three different inducible NO synthase (iNOS) inhibitors at various concentrations 24 hr, apart; aminoguanidine (AG), guanidinoethyldisulfide (GED), and n-(3-aminomethyl)benzylacetamidine (1400W). Rats were killed four days after the initial injection and small intestinal mucosa was assayed for myeloperoxidase (MPO) activity and iNOS expression by western blot analysis. Serum nitrite/nitrate (NOx) concentration was measured colorimetrically. INDO produced acute ulcers along the mesenteric border from the ileum to proximal jejunum. Rats treated with AG (25 and 50 mg/kg), GED (2.5 mg/kg), and 1400W (0.1 mg/kg) showed decreased total ulcer length and MPO activity by 51, 72, 53, and 61% and by 58, 88, 68, and 70%, respectively, compared to INDO alone. All inhibitors similarly reduced INDO-enhanced serum NOx concentrations to its basal levels. Significant iNOS expression was detected in INDO-treated rats, but the inhibitors did not alter iNOS expression. Our data suggest that NO derived from iNOS may be a key factor in the pathogenesis of acute INDO-induced enteropathy in rats.

Role of nitric oxide in acidosis-induced intestinal injury in anesthetized rats

We investigated the pathogenic mechanism(s) of small intestinal injury during acidosis in relation to circulating nitric oxide (NO) in an experimental rat model. Rats were anesthetized, paralyzed, and mechanically ventilated with room air. Hydrochloric acid (0.16 mmol bolus followed by 0.132 mmol/kg/h) was infused through the jugular vein for 5 hours. Control rats received a saline infusion. Arterial blood gases, blood pressure, and blood pH were measured every 30 minutes. The involvement of NO in this acidosis model was assessed by measuring plasma concentration of nitrite/nitrate (NOx) and by evaluating inducible NO synthase (iNOS) expression in small intestinal mucosa. Intestinal injury was assessed by measuring myeloperoxidase (MPO) activity, thiobarbituric acid reactants (TBARS), and histologic scores. HCl infusion was associated with hypotension, decreased blood pH, increased plasma concentration of NOx, augmented intestinal mucosal iNOS expression, MPO activity, TBARS, and histopathologic injury scores. Pretreatment with an iNOS inhibitor, aminoguanidine (AG, 50 mg/kg), reversed HCl-induced hypotension without a change in blood pH. HCl-induced lesions, MPO activity, TBARS, and plasma NOx production were decreased by AG. Our data show that the pathogenic mechanisms of acidosis-induced small intestinal lesions involve up-regulation of NO production by increased expression of iNOS and augmentation of superoxide radicals and MPO activity.

Anthropophily of Anophelines in Duars of West Bengal and other regions of India

Attempts have been made to identify the source of blood meals of twenty three anopheline species from various areas of high malaria endemicity in India. Anopheles minimus, Anopheles fluviatilis and Anopheles dirus showed a high propensity for human blood in North-Eastern parts of the country while Anopheles sundicus was found to be anthropophilic in Andaman & Nicobar Islands. Anopheles culicifacies, Anopheles maculatus and Anopheles philippinensis were found primarily zoophilic in north-eastern areas. High anthropophily has been closely related to sporozoite infection in anophelines specially in Anopheles minimus and is of great epidemiological significance.

Efficacy of chloroquine in febrile Plasmodium falciparum infected children in Mewat region of Haryana

During 1996, Mewat region of Gurgaon district in Haryana experienced high incidence of Plasmodium falciparum malaria, assuming epidemic proportion in large number of villages affected by floods. Mortality due to fever was also high. In vivo 7 days study amongst 32 febrile P. falciparum infected children of 1 to 14 years age group in flood affected villages of Ferozpur Jhirka Community Health Centre of Mewat region was carried out. All the 32 cases showed good response to chloroquine suggesting that drug was effective and useful as first line of treatment, reducing severity of P. falciparum infection and resolving fever due to infection of the species. The study also indicated that chloroquine was an effective drug in controlling epidemic situation and mortality in areas of high incidence of P. falciparum. Pyrogenic stimulus was variable among different developmental stages of P. falciparum and suggestive of the need of earliest possible initiation of anti-malaria treatment, community based fever survey and blood smear examination. Increase in incidence of fever in an endemic community, particularly in children, should be considered as an indicator of impending outbreak of P. falciparum malaria. Effectiveness of diagnostic and control measures taken can be evaluated on the basis of incidence of malaria particularly due to P. falciparum infection and also incidence of fever in an endemic community.

Dietary nucleotides augment dextran sulfate sodium-induced distal colitis in rats

We have previously shown that enteral and parenteral supplementation of nucleotides (NT) accelerates healing of small-bowel ulcers in rats with indomethacin-induced ileitis. The purpose of this study was to evaluate whether dietary NT supplementation would similarly affect ulcer healing in dextran sulfate sodium (DSS)-induced colitis in rats. Male Sprague-Dawley rats were randomly assigned to receive either nucleotide-free (NF) or NT-supplemented diets. After 2 d of prefeeding, colitis was induced by including 40 g/L of DSS in drinking water for 3 d, followed thereafter by tap water. Rats from each group were killed at 7 and 12 d after induction of colitis. Additional rats were also used for both the groups as controls (untreated groups). The length of colon was measured and evaluated by histological score. Colonic myeloperoxidase (MPO) activity was assessed. In a separate series of experiments, rats were studied at 0, 4, 7, and 12 d for interleukin-1beta (IL-1beta) in rectal dialysate and plasma. Ulceration predominated in the distal colon in DSS-treated rats. There was no significant difference between the histological scores of the NF and NT-supplemented groups either at 7 or 12 d. MPO activity at 7 and 12 d was significantly higher in the NT-supplemented compared to NF group (7 d: 1013 +/- 172 vs. 409.9 +/- 103.2; 12 d: 471.9 +/- 112.4 vs. 223.6 +/- 21.6 units. min-1. g colon-1). IL-1beta concentration in rectal dialysate was significantly higher at 7 d in both groups compared to 0 and 4 d. At 12 d it continued to be significantly elevated in the NT-supplemented group and was greater than in the NT-free group. Our data on the proinflammatory cytokine, in conjunction with MPO activity, strongly suggest that NT supplementation aggravates the severity of DSS-induced colitis in rats.

Expression and characterization of protein kinase C in isolated rabbit parietal cells

We investigated the expression, characterization and distribution of protein kinase C (PKC) isozymes in isolated rabbit parietal cells (PC). Cellular extracts of PC were analyzed by Western blot using isozyme-specific antibodies. The Ca2+-independent PKC-epsilon was detected in cytosolic, membrane and cytoskeletal fractions of basal and histamine-stimulated PC, whereas the Ca2+-dependent PKC-alpha was confined to the cytosolic and membrane fractions. Cytosolic and membrane fractions were partially purified by DEAE cellulose column chromatography with elution of increasing NaCl concentration. Eluates of 0.15 M and 0.3 M NaCl PC fractions were identified as PKC-alpha and -epsilon isoforms, respectively. Phorbol 12-myristate 13-acetate (TPA) treatment of PC for 15, 30 and 60 sec decreased significantly cytosolic PKC-alpha and increased membrane-associated PKC-alpha. In contrast to the distribution of PKC-alpha, TPA did not alter membrane or cytosolic level of PKC-epsilon. Comparison of the dose-response curves between TPA-induced hydrogen (H+) secretion, as measured by aminopyrine (AP) uptake, and the membrane-associated PKC-alpha suggests that translocation of PKC-alpha is not involved in the H+ secretory process in PC. Furthermore, a PKC inhibitor, staurosporine, produced a concentration-dependent enhancement of histamine-stimulated H+ secretion. These findings suggest that PKC-alpha plays a negative modulatory role, rather than an obligatory role, in H+ secretion. The localization and distribution of PKC-epsilon into the cytoskeletal fraction of PC also suggests that this isozyme may be involved in the cellular regulation of reversible morphological transformation during stimulation.

Acidosis stimulates nitric oxide production and lung damage in rats

Systemic hypotension during sepsis is thought to be due to nitric oxide (NO) overproduction, but it may also be due to acidosis. We evaluated in healthy rats the consequences of acid infusion on NO and blood pressure. Sprague-Dawley rats were anesthetized, and ventilated with room air. The animals were randomized into four groups. Group 1 (C, n = 10) received only normal saline at rates comparable to the other groups. Group 2 (A1, n = 10) received hydrochloric acid at 0.162 mmol in the first 15 to 30 min, followed by a continuous infusion of 0.058 mmol/h for 5 h. Group 3 (AG+A1, n = 6) was pretreated with aminoguanidine (AG, 50 mg/kg), and HCl was infused as above. Group 4 (A2, n = 7) received HCl at twice the rate used in A1. Nitric oxide concentration in the exhaled gas (ENO), blood gases, and mean arterial pressure were measured every 30 min. Acid infusion in A1 caused the pH to fall gradually from 7.43 +/- 0. 01 to 7.13 +/- 0.05. This moderate decrease in pH was associated with a marked increase in ENO (1.6 +/- 0.3 to 114.2 +/- 22.3 ppb), an increase in plasma nitrite/nitrate (17.3 +/- 3.7 to 35.2 +/- 4.3 microM), and a significant decrease in blood pressure (110.5 +/- 6.3 to 63.3 +/- 15.0 mm Hg). Furthermore, acidosis caused lung inflammation, as suggested by the increase in lung myeloperoxidase activity (282.2 +/- 24.7 to 679.3 +/- 57.3 U/min/g) and lung injury score (1.7 +/- 0.2 to 3.5 +/- 0.6). Acidosis after AG pretreatment was associated with a similar change in pH, but the increase in ENO, nitrite/nitrate, and systemic hypotension were prevented. Furthermore, lung injury was attenuated by AG, as suggested by a lower myeloperoxidase activity, though lung injury score was not altered. In this model, moderate acidosis causes increases in NO, hypotension, and lung inflammation. Lung inflammation and injury are due in part to acidosis and NO production. This is the first report to show a direct effect of chronic acidosis on NO production and lung injury. These results have profound implications on the role of acidosis on NO production and lung injury during sepsis.

Induction of an ATPase inhibitor protein by propylthiouracil and protection against paracetamol (acetaminophen) hepatotoxicity in the rat

1. The purpose of the present study was to test the following hypothesis: propylthiouracil (PTU) treatments of rats induces an increase in the concentration and activity of the mitochondrial ATPase (m-ATPase) inhibitor protein (IF1). The PTU-induced elevated baseline levels of this inhibitor protein inactivated m-ATPase, and prevented hepatotoxicity by a toxic dose of acetaminophen (AAP) (paracetamol), by maintaining hepatic adenosine 5'-triphosphate (ATP) levels. 2. Male Wistar rats were either gavaged with a toxic dose of AAP alone, or after pretreatment with PTU for periods of 3 and 12 days. 3. Twenty four hours after acetaminophen treatment alone, toxicity was manifested by: an approximately 10 fold increase in serum transaminase levels (serum glutamic oxaloacetic transaminase and serum glutamic pyruvic transaminase); depletion of hepatic reduced glutathione (GSH) and ATP levels; loss of inhibitor protein activity, and extensive pericentral necrosis of the hepatocytes. Propylthiouracil pretreatment for 12 days enhanced the concentration of the following metabolites in the liver: ATP (1.5 fold), ATPase inhibitor protein (IF1) (4.5 fold), and reduced glutathione (1.3 fold), while the activity of the inhibitor protein increased 2 fold. When the PTU treated rats were challenged with AAP, transaminases were not elevated, and only sporadic areas of necrosis were detected by histological examination of the liver tissue. In contrast to the 12 day treatment with PTU the 3 day treatment had no protection against AAP. No histological evidence of protection was manifested and the transaminases were not different from AAP treated controls. Most of the protective metabolites were depleted. 4. Our findings suggest that PTU-induced increased concentration of inhibitor protein and GSH, are contributing factors in the prevention of hepatotoxicity by maintaining hepatic m-ATP levels and reducing the harmful effect of the toxic metabolite of AAP.

Dietary supplementation of nucleotides and arginine promotes healing of small bowel ulcers in experimental ulcerative ileitis

We previously showed that intravenous total parenteral nutrition supplemented with nucleosides and nucleotides (NS/NT) promoted ulcer healing in rats with indomethacin-induced ileitis. The present study evaluated whether dietary NT supplementation would similarly affect ulcer healing in this model. Female Lewis rats were randomized into either control or experimental groups receiving yeast RNA containing NT or arginine, glutamine, fish oil, guar gum, or a combination of yeast RNA+arginine diets. Ileitis was induced by two doses of indomethacin (7.5 mg/kg) administered subcutaneously 24 hr apart. Ulcer number and length were determined at 4, 8, and 14 days after induction of ileitis. Ileal villous and crypt length, crypt-villous ratio, and bromodeoxyuridine (BrdU) labeling were studied in the control and yeast RNA-supplemented diet groups. Ileal ulceration was present in all groups at 4 and 8 days and was almost healed by 14 days. Rats receiving yeast RNA, arginine, and yeast RNA + arginine diets showed a significant decrease in ulcer number (56%, 28%, and 34%, respectively) and length (67%, 41%, and 48%, respectively) compared to controls at 8 but not at 4 days. Glutamine, fish oil, and guar gum had no effect on ulcer healing at 4, 8, or 14 days. Among the histological parameters, a significant decrease in crypt length in the yeast RNA-supplemented group at 8 days suggested an acceleration of the healing process and restoration to a near-normal crypt-villous architecture. We conclude that the yeast RNA, arginine, and yeast RNA + arginine diets accelerated ulcer healing, as indicated by decreased ulcer number and length. We postulate that the underlying mechanism(s) contributing to ulcer healing may be related, in part, to increased cell proliferation.

Ecological observations on the anopheline mosquitoes of Jalpaiguri Duars, West Bengal

A nine month entomological study was conducted from August 1989 to April 1990 in Jalpaiguri duars of West Bengal where malaria has been persistent problem. Amongst the anopheline fauna three vector species were recorded; An. minimus was the principal vector supported by A. dirus during the rainy months and An. fluviatilis in dry months. All the three vectors were found in close association with human orbit and An. minimums was found to be primarily a domestic vector. The primary role of An. minimus in the transmission of malaria in the region has been highlighted. Observations on seasonal variation, biting preferences, and biting time and vector infection rates were recorded.

Effects of a phorbol ester and isoquinoline sulfonamides on rabbit parietal cell function

The role of protein kinase C (PKC) on gastric H+ secretion, as measured by aminopyrine (AP) uptake and other intracellular signal transduction products, was investigated in isolated rabbit parietal cells using the PKC activator 12-0-tetradecanoyl phorbol 13-acetate (TPA) and several PKC inhibitors, including isoquinoline sulfonamides (H-7, H-8, H-89 and HA-1004) and calphostin-C. TPA dose-dependently inhibited histamine (10(-4) M)- and carbachol (10(-4) M)-stimulated AP uptake without affecting the response to dibutyryl cyclic AMP (10(-3) M). H-7 and calphostin-C dose-dependently augmented secretagogue-stimulated AP uptake, whereas H-8 and H-89 inhibited the response to secretagogues, and HA-1004 had no effect. H-7 and calphostin-C-induced augmentation of AP uptake was blocked by a calcium (Ca++) antagonist, lanthanum chloride, which suggests that the enhanced AP response was regulated by extracellular Ca++. Moreover, H-7 treatment partially reversed the TPA (10(-7) M)-induced inhibition of secretagogue-stimulated AP uptake. TPA reduced histamine- and carbachol-stimulated cAMP and inositol 1,4,5-triphosphate production by 50% and 96%, respectively, with a concomitant reduction of adenylate cyclase and intracellular free Ca++ by 44% and 78%. TPA increased the distribution of membrane-associated PKC by 20% and decreased histamine-stimulated PKA by 30%. In contrast, H-7 inhibited both PKC and protein tyrosine kinase activity in vitro but had no effect on these parameters in vivo. The results indicate that TPA-induced inhibition of secretagogue-stimulated AP uptake in PC is presumably mediated by activation of PKC.

Mode of food intake reduction in Lewis rats with indomethacin-induced ulcerative ileitis

The mechanism of anorexia in inflammatory bowel disease is poorly understood. To gain insight into possible pathophysiologic mechanisms, the feeding indices and food intake were studied in an animal model of Crohn's disease. The anorexia of indomethacin-induced ulcerative ileitis was compared with that of the well-known anorexia of total parenteral nutrition (TPN). Forty-five female Lewis rats were randomized to four groups: Control, Indomethacin, Indomethacin + TPN, and TPN. Feeding indices and food intake were continuously measured using the Automated Computerized Rat Eater Meter. Interleukin-1 alpha (IL-1 alpha), tumor necrosis factor-alpha (TNF-alpha), prostaglandin E2 (PGE2), and leukotriene B4 (LTB4) were assayed in plasma, mononuclear cell culture, or ileum to determine their role in mediating anorexia. In the TPN group, spontaneous food intake (SFI) decreased (52%; p < 0.05), primarily via reduction in meal number (MN, 54%; p < 0.05) and, to a lesser extent, meal size (MZ, 35%; p < 0.05). In comparison, in the Indomethacin group SFI decreased (74%; p < 0.05) primarily via reduction in MZ (67%, p < 0.05); MN also decreased but to a lesser extent (27%; p < 0.05). In the Indomethacin + TPN group, SFI decreased (55%; p > 0.05) primarily via reduction in MN (79%; p < 0.05), whereas MZ decreased slightly (19%; p < 0.05). Only in the Indomethacin group were IL-1 alpha and TNF-alpha detected in the mononuclear cell culture and plasma, respectively. In the Indomethacin group, an inverse correlation existed between MZ and TNF-alpha (p < 0.05). In the Indomethacin group, IL-1 alpha, PGE2, and LTB4 concentrations did not correlate with feeding indices. SFI reduction in this model was mediated primarily via a decrease in MZ. TNF-alpha is proposed to mediate this effect and TPN was shown to overcome the effect on MZ.

Tyrosine phosphorylation as a possible regulatory mechanism in the expression of human immunodeficiency virus genes

Phosphorylation of proteins on serine, threonine and tyrosine is one of the significant regulatory mechanisms in gene expression and post-translational modifications in both eukaryotes and prokaryotes. Protein tyrosine phosphorylation in particular is implicated in cell proliferation, differentiation and certain pathological modifications including transformation. The overall protein tyrosine phosphorylation is modulated by protein tyrosine kinases (PTK) and protein tyrosine phosphatases (PTP). There are several viruses known to contain PTK and PTPs. A computer-based protein sequence search using the FAST P programme was used to investigate whether, theoretically, a sequence for a putative protein tyrosine phosphatase is present in the genomic sequence of the human immunodeficiency virus (HIV). A conserved motif GXGXXG characteristic of both PTK and PTP was found at the 5' LTR region of the HIV genome. Interesting sequence similarities with regulatory proteins of other retroviruses, viz. VPx of HIV-2 and X-protein of HTLV-1, and some transforming proteins were also observed. The implication of the possible phosphorylation event in association with the HIV regulatory proteins tat, rev and nef in AIDS-related malignancies is discussed.

Effects of cyclic adenosine monophosphate-dependent protein kinase and calcium-dependent protein kinase modulators on stimulated gastric acid secretion in the perfused rat stomach

The effects of cyclic adenosine monophosphate-dependent protein kinase (PKA) and calcium-dependent protein kinase (PKC) modulators on secretagogue-stimulated gastric acid secretion were studied in the continuously perfused stomach of the anesthetized rat. Intravenous histamine (0.25 mg/kg/h) and pentagastrin (2 micrograms/kg/h) increased secretion above baseline by three- and fourfold, respectively. Parenteral administration of a PKC activator, 12-o-tetradecanoylphorbol-13-acetate (TPA; 0.1 nmol/h), decreased histamine- and pentagastrin-stimulated secretion by 64 and 40%, respectively. Administration of PKC inhibitors, calphostin C and 1-(5-isoquinolinyl sulfonyl)-2 methylpiperazine (H-7; 10 nmol/h, each), increased histamine- and pentagastrin-stimulated secretion by 115 and 74% and 42 and 79%, respectively, while equimolar concentrations (10 nmol/h) of three other isoquinoline sulfonamides (HA-1004, H-8, and H-89) had no effect, except for H-89 (100 nmol/h) which inhibited the histamine- and penta-gastrin-stimulated acid secretion by 44%. Basal secretion was not significantly altered by the aforementioned drugs. The TPA-induced inhibition of pentagastrin-stimulated secretion was partially reversed by treatment with H-7. These findings support a role of PKA and PKC in the modulation of stimulated gastric acid secretion in vivo.

Chloroquine versus amodiaquine in the treatment of Plasmodium falciparum malaria in northeast India

Amodiaquine is being used in India for presumptive treatment as an alternative to chloroquine in areas with chloroquine resistant P. falciparum. Keeping in view the toxicity of amodiaquine, studies have been undertaken to evaluate the advantage of the drug over chloroquine in the treatment of P. falciparum malaria. In vivo drug resistance studies were carried out in the states of Assam and Meghalaya in India. A total of 388 subjects have been studied to compare the efficacy of chloroquine and amodiaquine. The overall cure rate, degree of resistance, mean parasite clearance time and mean parasite recrudescence time were comparable for both the drugs, the differences being not statistically significant. The results indicate no advantage of amodiaquine in the treatment of patients with P. falciparum infection in chloroquine resistant areas of northeast India and development of cross resistance in P. falciparum to these 4-aminoquinolines is complete and parallel.

Status of chloroquine resistance in Plasmodium falciparum in Tripura

In-vivo chloroquine resistance studies on P. falciparum were conducted in 1981 and 1988 in South district of Tripura. Resistance status to chloroquine has been gradually changing over the seven years period. A single case at RIII level was detected in 1988, and RI level of resistance had shown a increasing trend.

Performance evaluation of a particle agglutination test for antibody to human immunodeficiency virus 1: comparison with enzyme immunoassay

A performance evaluation of a particle agglutination test (PAT), manufactured by Fujirebio Inc., Japan (Serodia-HIV), for antibody to human immunodeficiency virus type-1 (anti-HIV-1) was carried out and compared with a currently available enzyme immunoassay (EIA), manufactured by Genetic Systems Corp., USA, (HIV-1/HIV-2 EIA). Testing 2,878 Indian donor and patient samples, both tests showed 100% sensitivity and comparable specificity (PAT: 99.8%; EIA: 99.7% among donor samples). We conclude that PAT is a specific and sensitive test for anti-HIV-1; it is simple to perform and does not require sophisticated equipment. Hence it is suitable for mass screening of blood donors in a developing country like India, especially in rural areas where presently no HIV-testing facilities are available.

Effects of nonsteroidal antiinflammatory drugs on ulcerogenesis and gastric secretion in pylorus-ligated rat

The effects of nonsteroidal antiinflammatory drugs on ulcerogenesis and gastric secretion were evaluated in a pylorus-ligated rat model. Oral administration of salicylate (50 mg/kg), aspirin (50 mg/kg), and indomethacin (3.5 mg/kg) significantly increased ulcerogenesis over the basal value by six- to sevenfold, but ibuprofen's (10 mg/kg) fourfold increase was not significant. Aspirin in conjunction with histamine (0.5 mg/kg subcutaneously) significantly increased ulcerogenesis by 2.7-fold compared to histamine alone. Basal acid secretion was increased significantly by 156% after indomethacin, but not by other nonsteroidal antiinflammatory drugs. In contrast, all nonsteroidal antiinflammatory drugs, except indomethacin, significantly decreased histamine-stimulated acid secretion. Non-steroidal antiinflammatory drugs had no effect on pepsinogen secretion. Ranitidine pretreatment (25 mg/kg intraperitoneally) significantly decreased basal acid and pepsinogen secretion in all treatment groups by > 85% and > 40%, respectively, and ulcerations induced by salicylate, aspirin, and indomethacin were also inhibited by 90%, 60%, and 60%, respectively. The observed inhibition of prostaglandin E2 generation by nonsteroidal antiinflammatory drugs under basal secretory conditions appeared to correlate with the extent of ulcerogenesis. Our data support the concept that acid, in addition to inhibition of prostaglandin E2 synthesis, plays an important role in the pathogenesis of nonsteroidal antiinflammatory drug-induced gastropathy.

Detection of human immunodeficiency virus antibody among homosexual men from Bombay

BACKGROUND AND OBJECTIVES

In India, heterosexual transmission of HIV-infection is considered to be the major mode of transmission. However, no report is available on transmission of HIV-infection among homosexually active men. The prevalence of human immunodeficiency virus-1 (HIV-1) and human immunodeficiency virus-2 (HIV-2) infections among homosexual men from Bombay is discussed.

GOAL OF THE STUDY

To determine the extent of presence of anti-HIV-1, anti-HIV-2 antibodies, or both anti-HIV-1 and anti-HIV-2 antibodies among homosexual men in India.

STUDY DESIGN

Sixty-three blood samples were collected from two STD clinics of Bombay over a 6-month period from men with a history of homosexual behavior who were asymptomatic for HIV-infection. The mean age of the subjects was 31.6 years. For serological detection anti-HIV-1 antibody ELISA was used as the primary screening test followed by Western blot to confirm the results. For distinction between anti-HIV-1 and anti-HIV-2 antibody, line immunoassay was used. The sexually transmitted diseases (STDs) were diagnosed clinically, although Venereal Disease Research Laboratory (VDRL) tests were carried out as a routine test for screening STDs. For detection of gonorrhea, Gram stains of urethral smear were done routinely.

RESULTS

From the 63 blood samples tested, 10 samples were reactive by ELISA for HIV-1 infection, and three samples were borderline reactive. These three samples were found to be reactive for anti-HIV-2 by the line immunoassay. The above 10 samples were also positive by Western blot for anti-HIV-1 antibody. Two blood samples were positive for both anti-HIV-1 and anti-HIV-2 antibodies. Using clinical diagnosis as the criteria, the different types of STD among the 63 subjects were as follows: condylomata (22), herpes (20), gonorrhea (15), candidiasis (3), and syphilis (3). However with VDRL, seven subjects were found to be reactive. Gram stains indicated gonorrhea in all the 15 subjects.

CONCLUSIONS

This study reports for the first time the homosexual transmission of both HIV-1 and HIV-2 infections in India, although heterosexual transmission still is the major mode of transmission of the infection. The associated incidence of STDs among these men and that a few of these subjects were bisexual make them at high risk for transmission of HIV infection.

A possible role of protein kinase C in augmenting H+ secretion by nonsteroidal anti-inflammatory drugs

The effects of nonsteroidal anti-inflammatory drugs (NSAIDs) on H+ secretion were studied in frog gastric mucosa and rabbit parietal cells (PC). In frog gastric mucosa, aspirin (10(-5) M) and ibuprofen (10(-4) M), but not indomethacin, naproxen and carprofen (10(-4) M each), enhanced histamine- and dibutyryl adenosine 3',5'-cyclic monophosphate-stimulated H+ secretion by 20 to 34%. Similarly, a protein kinase C (PKC) inhibitor, 1-(5-isoquinolinesulfonyl)- 2-methyl piperazine (H7, 5 x 10(-5) M), and a calcium ionophore, A23187 (10(-6) M) augmented basal and the aforementioned secretagogue-stimulated H+ secretion by approximately 50% and 20%, respectively, but a PKC activator, phorbol ester (12-O-tetradecanoyl phorbol 13-acetate, 10(-7)-10(-6) M), had no effect. The augmentation of H+ secretion by these agents was blocked by a calcium antagonist, lanthanum chloride (5 x 10(-4) M). In rabbit PC, H7 augmented secretagogue-stimulated H+ secretion by 60 to 150%, whereas 12-O-tetradecanoyl phorbol 13-acetate (10(-7) M) inhibited carbachol- and histamine-stimulated H+ secretion, respectively, by 65% and 52% without affecting dibutyryl adenosine 3',5'-cyclic monophosphate-stimulated H+ secretion. Furthermore, NSAIDs and H7-induced augmentation of dibutyryl cyclic adenosine monophosphate-stimulated H+ secretion was prevented by 12-O-tetradecanoyl phorbol 13-acetate (10(-7)-10(-6) M) in frog gastric mucosa and rabbit PC. Unlike H7, NSAIDs had no direct inhibiting action on PC membrane or cytosolic fractions of PKC, but they inhibited Sn-1,2-diacylglycerol level in PC by 20 to 30%.(ABSTRACT TRUNCATED AT 250 WORDS)

Human immunodeficiency virus-1 infection in spouses of seropositive individuals

BACKGROUND

Unprotected sex can lead to transmission of the human immunodeficiency virus-1 (HIV-1) to the spouse of an infected individual. We studied the incidence of HIV-1 infection in the spouses of cases diagnosed to have HIV-1 infection by serology and the polymerase chain reaction (PCR).

METHODS

Blood samples collected from 9 index cases and their respective spouses were tested for HIV-1 infection by ELISA, Western blot (WB) and PCR as well as from 10 healthy individuals with no high-risk behaviour. DNA extracted from both plasma and peripheral blood mononuclear cells was amplified by PCR, using multiple primer pairs for distinct regions of the HIV-1 genome. Specificity of the PCR product was demonstrated by hybridization to an oligonucleotide probe.

RESULTS

All the index cases which were seropositive by ELISA and WB were also positive by PCR of plasma extracted DNA. Eight of the spouses were seronegative. Of these seven were positive by PCR--one spouse was negative by ELISA but showed a p55 band on WB and was positive by PCR. One spouse was negative by serology and PCR. The spouse belonging to the lone concordant couple was positive by serology and PCR. Except for one index case, PCR signals were obtainable only from DNA extracted from plasma but not from the DNA extracted from peripheral blood mononuclear cells. The control samples were negative by serology and PCR.

CONCLUSION

It is possible to detect HIV-1 infection by PCR using DNA extracted from plasma even when the individuals are negative by ELISA and WB. It can help in the early counselling of HIV infected persons and their spouses.

Malaria transmission in Nagaland, India. Part-I--Anophelines and their seasonality

A longitudinal study on malaria transmission was conducted from January 1983 to December 1988 in two villages of Dimapur PHC in Nagaland. A diverse anopheline fauna comprising of 23 species was identified including three species viz. An. aitkeni, An. bengalensis and An. insulaeflorum which were observed in larval stages only. An. vagus was the predominant species followed by An. philippinensis, An. culicifacies and An. minimus. An. minimus though maintained relatively high density throughout the year manifested two peaks in June and October. An. fluviatilis and An. dirus though found in relatively low density their seasonal prevalence was suggestive of a post-monsoon and monsoon species respectively.

Present perspectives of malaria transmission in Boko area of Assam

A longitudinal study on malaria transmission was conducted from January 1984 to December 1988 in three villages in Boko PHC of Assam, where indoor residual DDT spray was withdrawn during the period of study. Anopheline fauna comprising of 19 species was identified and their seasonal density estimated. Anopheles philippinensis was the predominant species followed by An. minimus. The principal role of An. minimus in the transmission of malaria and predilection for indoor resting in this area was clearly evident. Though An. dirus and An. fluviatilis were found in low density, sporozoite infection was detected in them along with An. minimus. The high malaria incidence predominantly with Plasmodium falciparum was closely related to sporozoite infection in the vectors and their densities. The biting cycle of An. minimus was maximum in the first half of the night.

Alternative mode of replication of human immunodeficiency virus: a hypothesis

For diagnosis of Human Immunodeficiency Virus (HIV) infection by the recently developed Polymerase Chain Reaction (PCR), the two commonly used clinical samples are either the peripheral blood monocytes (PBMC) or the plasma of the infected individuals. In the former instance, DNA is extracted from PBMC. The integrated proviral DNA is then amplified using HIV specific oligonucleotide primers. In the latter instance, RNA is extracted from plasma. This is reverse transcribed in vitro into cDNA by using extraneous reverse transcriptase. This cDNA is then used as a target in PCR experiments with HIV specific primers. In contrast we have recently used DNA directly extracted from plasma of infected individuals. This DNA was used for amplification of HIV genome with primer pairs specific for HIV. An interesting outcome of this study was a model to explain the presence of DNA of HIV in the plasma. We suggest that possibly there is an alternative mode of replication of HIV. Apart from the obligatory integration of the DNA of HIV into the DNA of lymphocytes as provirus, several additional copies of the DNA are also made which remain unintegrated. These probably exist as a housekeeping repertoire of the viral genome. These DNA molecules may be released into the circulation along with the newly formed mature virion particles during the usual course of replication and release of the virus. In our experiments with direct extraction of DNA from plasma, these unintegrated DNA of HIV may act as the target for PCR to give positive signals with HIV specific primers.

Detection of hepatitis B virus DNA in donor blood by the polymerase chain reaction

BACKGROUND

Blood collected from voluntary donors at local blood banks and blood donation camps was screened for the hepatitis B virus genome using the polymerase chain reaction and for viral markers by standard serological techniques. The sensitivities of the two screening strategies were compared.

METHODS

One hundred and twenty-six blood samples were tested for HBV serological markers--HBsAg, anti-Hbs and anti-HBc--by ELISA: The same samples were also subjected to the polymerase chain reaction using primers made by us.

RESULTS

Analysis of the polymerase chain reaction amplified products revealed that 24% of the blood samples which tested negative for HBsAg using the ELISA technique were positive for HBV DNA by the polymerase chain reaction. All the HBsAg positive samples (by ELISA) were also positive by the polymerase chain reaction (which detected additional samples as well). Anti-HBc antibodies showed a much greater concordance with the polymerase chain reaction.

CONCLUSIONS

The results emphasize that the screening strategies for donor blood need to be re-evaluated in order to check inadvertent transmission of hepatitis B virus during blood transfusion. The ELISA technique to detect HBsAg as the sole serological marker is inadequate to indicate the actual prevalence of hepatitis B virus in the donor blood. The polymerase chain reaction may be a better screening test. If this is not available, the detection of anti-HBc antibodies appear to be a better means of screening blood than HBsAg.

Nonsalicylate nonsteroidal antiinflammatory drugs augment prestimulated acid secretion in rabbit parietal cells. Investigation of the mechanisms of action

The effects of nonsalicylate nonsteroidal antiinflammatory drugs on acid secretion were studied in isolated rabbit parietal cells. Indomethacin, naproxen, and carprofen (10(-6)-10(-4) mol/L) potentiated histamine-, forskolin-, 3-isobutyl-1-methylxanthine-, and dibutyryl cyclic adenosine monophosphate-stimulated acid secretion without affecting basal acid secretion. This augmentation of secretagogue-stimulated acid secretion was dependent on extracellular calcium because potentiation was abolished by calcium depletion of the medium or in the presence of the calcium antagonist lanthanum chloride. Potentiation was independent of the H2 and muscarinic receptors and did not appear to involve guanine nucleotide regulatory proteins. Proton pump activity was unaffected by indomethacin. Furthermore, nonsteroidal antiinflammatory drugs increased calcium efflux through the plasma membrane, as measured by calcium 45, and decreased endogenous prostaglandin E2 content. Exogenous dimethyl prostaglandin E2 inhibited the potentiating effect of these drugs on histamine-stimulated but apparently not on dibutyryl cyclic adenosine monophosphate-stimulated acid secretion. The data indicate that nonsalicylate nonsteroidal antiinflammatory drugs interacted at a postreceptor site between adenylate cyclase and the proton pump. The potentiating effects of these drugs were regulated by calcium and possibly modulated by prostanoids.

Purification of antigen for serodiagnosis of echinococcosis

Antigen for serodiagnosis of Echinococcosis is purified by chromatography on DEAE-Cellulose and Sephadex G-200 from hydatid cyst fluid. The antigen is electrophoretically pure and found sensitive and specific for Echinococcus granulosus. The antigen is thermostable and is apparently a lipo protein.

Aspirin potentiates prestimulated acid secretion and mobilizes intracellular calcium in rabbit parietal cells

The effects of aspirin on gastric acid secretion were studied in isolated rabbit parietal cells (PC). Aspirin (10(-5) M) potentiated histamine-, dibutyryl cyclic AMP (dbcAMP)-, forskolin- and 3-isobutyl-1-methylxanthine-stimulated acid secretion without affecting basal acid secretion. Augmentation of secretagogue-stimulated acid secretion by aspirin was dependent on calcium (Ca2+) since potentiation was blocked by removal of extracellular Ca2+ ([Ca2+]o) or addition of the calcium antagonist lanthanum chloride. Using the Ca2+ probe fura-2, aspirin (10(-6) - 2 X 10(-5) M) rapidly increased intracellular free Ca2+ concentration ([Ca2+]i) in a dose-dependent manner. The source of released Ca2+ was intracellular as demonstrated by depletion of intracellular Ca2+ and [Ca2+]o with EGTA washing. Aspirin did not affect several other signal transduction sites involved in stimulus-secretion coupling, including the H2 receptor, intracellular cyclic AMP (cAMP), inositol 1,4,5, triphosphate (IP3) and H+,K(+)-ATPase. Aspirin decreased PC prostaglandin E2 (PGE2) content by 98%. Exogenous dimethyl PGE2 (dmPGE2) inhibited both histamine-stimulated acid secretion and its enhancement by aspirin. In contrast, dmPGE2 abolished aspirin-induced potentiation of dbcAMP-stimulated acid secretion by augmenting the dbcAMP-stimulated response. These results indicate that aspirin acts at a site beyond the adenylate cyclase/cAMP system and before the proton pump, presumably by releasing Ca2+ from an IP3-independent intracellular storage pool and by inhibiting PGE2 generation.

Characterization of third beta-chain variant in Rattus rattus rufescens

Different molecular forms of hemoglobins of locally available murines, represented by Rattus rattus rufescens, have been investigated and the probable genetic mechanisms leading to the observed heterogenicity in the hemoglobin phenotypes are discussed. Each fraction was isolated in chromatographically pure form, identified and characterised structurally to establish their alpha- and non-alpha-chain constitution. Six molecular forms of component hemoglobins were identified from a wild population of R. rattus rufescens. The present study suggests five different globin chains in the hemoglobin of house rats (Rattus rattus rufescens). There are apparently two alpha-chains, namely alpha I and alpha II, and three different beta-chains, viz. beta I, beta II and beta III. The invariable presence, though at varying concentrations, of all these five globin chains implicates a gene duplication at the alpha-chain loci and a gene triplication at the beta-chain loci, the latter being a rather rare and unique genetic event.

Mechanisms of gastric proton pump inhibition by calcium channel antagonists

The inhibitory effects of Ca channel antagonists on gastric acid secretion [[14C]-aminopyrine (AP) uptake ratio] have been analyzed in isolated rabbit parletal cells (PC). Secretagogue-stimulated AP uptake was inhibited by verapamil and diltiazem in a dose-dependent manner with IC50 values of 15 and 100 microM, respectively, both in the presence and absence of extracellular Ca. In contrast, nifedipine had no effect on AP accumulation. Verapamil decreased histamine-stimulated respiration with the same IC50 as observed for AP uptake. Imidazole, a weak base, by buffering the acid spaces in PC, reversed the inhibitory effect of verapamil on respiration. In the bullfrog gastric mucosa, forskolin-stimulated proton transport was inhibited by verapamil (10(-4) M) from the luminal but not the serosal side. This inhibitory effect was reversed by either elevating KCl concentration in, or removing the drug from, the secretory solution. Verapamil inhibited gastric microsomal H+,K(+)-adenosine triphosphatase (H+,K(+)-ATPase) and PC K(+)-stimulated p-nitrophenyl phosphatase activities with a higher potency than diltiazem. Inhibition of these enzymes by verapamil and diltiazem was pH dependent. The drugs competed with K+ in both H+,K(+)-ATPase and K(+)-stimulated p-nitrophenyl phosphatase reactions. Our data suggest that inhibition of the gastric proton pump by verapamil or diltiazem is not due to their Ca channel antagonism but to their interaction with the luminal high affinity K(+)-site of the H+,K(+)-ATPase under acidic conditions.

Characteristics of the isolated apical plasmalemma and intracellular tubulovesicles of the gastric acid secreting cells: demonstration of secretagogue-induced membrane mobilization

Separation of the gradient-purified gastric microsome into two membrane subfractions of distinct enzymatic and phospholipid composition has been achieved by mild SDS (0.033% w/v) treatment followed by sucrose gradient centrifugation of the pig and rabbit gastric microsomes. While the high-density membranes had all of the (H+,K+)-ATPase and K+-pNPPase activities and revealed a single major 100-kDa band on SDS-PAGE, the low-density membranes contained all of the 5'-nucleotidase and nearly all of the Mg2+-ATPase. In the present study, the low-density subfraction has been characterized to be derived from the apical membranes and the high-density one from the intracellular tubulovesicular membranes of the parietal cells. Such characterization was based primarily on sole dependency of the apical plasma membranes on the endogenous activator for (H+,K+)-ATPase activity, differential sensitivity of the activator (AF)-dependent and -independent (H+,K+)-ATPase on micromolar vanadate and Ca2+, specific vitamin B12 binding ability of the apical plasmalemma, phospholipid and protein profiles of the two membrane subfractions, and other parameters. The AF, mentioned previously, has recently been implicated as a cytosolic regulator of the gastric (H+,K+)-ATPase [Bandopadhyay et al. (1987) J. Biol. Chem. 262, 5664-5670]. Two different forms (i.e., AF-dependent and -independent forms) of the (H+,K+)-ATPase are suggested to be present in the tubulovesicles on the basis of differential vanadate sensitivity while the AF-dependent form alone is present in the apical membranes. The data have been discussed in terms of stimulation-induced membrane transformation characteristic of the H+-secreting epithelia including the acid-secreting cells of the stomach.

Effects of nonsteroidal, antiinflammatory drugs on gastrointestinal injury and prostanoid generation in healthy volunteers

A new nonsteroidal, antiinflammatory drug, carprofen, was compared with indomethacin as to their effects on mucosal injury and prostanoid biosynthesis. A prospective, double-blind endoscopy study was performed in 40 healthy adults. After baseline normal endoscopy, 20 subjects were randomly assigned to either indomethacin (25 mg four times daily) or carprofen (150 mg twice daily) for eight days and re-endoscoped. Urinary and gastric mucosal prostaglandin generation, respectively, of PGE2 and PGF2 alpha, and PGE and 6-keto-PGF1 alpha was determined. Minor subjective symptoms occurred in six of 20 indomethacin (including four of eight with gastrointestinal injury) and in three of 20 carprofen subjects. Indomethacin and carprofen reduced gastric and urinary prostaglandin synthesis to a similar degree. Gastrointestinal injury was present in eight of 20 indomethacin and in none of 20 carprofen subjects. This study fails to establish a relationship between duodenal mucosal lesions and gastric prostanoid generation and confirms the lack of correlation between indomethacin-induced duodenal injury and subjective symptomatology. Carprofen appears to produce less objective damage in the upper gastrointestinal tract than indomethacin at comparable clinical doses.

Half of the (Na+ + K+)-transporting-ATPase-associated K+-stimulated p-nitrophenyl phosphatase activity of gastric epithelial cells is exposed to the surface exterior

Ouabain inhibited 86RbCl uptake by 80% in rabbit gastric superficial epithelial cells (SEC), revealing the presence of a functional Na+,K+-ATPase [(Na+ + K+)-transporting ATPase] pump. Intact SEC were used to study the ouabain-sensitive Na+,K+-ATPase and K+-pNPPase (K+-stimulated p-nitrophenyl phosphatase) activities before and after lysis. Intact SEC showed no Na+,K+-ATPase and insignificant Mg2+-ATPase activity. However, appreciable K+-pNPPase activity sensitive to ouabain inhibition was demonstrated by localizing its activity to the cell-surface exterior. The lysed SEC, on the other hand, demonstrated both ouabain-sensitive Na+,K+-ATPase and K+-pNPPase activities. Thus the ATP-hydrolytic site of Na+,K+-ATPase faces exclusively the cytosol, whereas the associated K+-pNPPase is distributed equally across the plasma membrane. The study suggests that the cell-exterior-located K+-pNPPase can be used as a convenient and reliable 'in situ' marker for the functional Na+,K+-ATPase system of various isolated cells under noninvasive conditions.

Effects of ethanol on parietal cell membrane phospholipids and proton pump function

The effects of ethanol on membrane phospholipids of isolated rabbit parietal cells (PC) and fundic glands (FG) were evaluated by using proton nuclear magnetic resonance spectroscopy (NMR). The most conspicuous resonance bands in PC and FG spectra at 3.2 and 0.9 ppm were due to the protons of +N(CH3)3 groups of phosphatidylcholine and, to a lesser degree, other phospholipid derivatives and terminal -CH3 groups for all phospholipids, respectively. Ethanol treatment (1 min) of PC and FG at 37 degrees C significantly increased the peak intensity of -CH3 groups in a dose-dependent manner, while no intensity change in PC and a lesser change in FG were observed for the +N(CH3)3 groups, suggesting a greater disorganizing effect of ethanol in the inner hydrophobic (-CH3) compared with the outer hydrophilic [+N(CH3)3] membrane moieties of phospholipids. Ethanol at concentrations greater than 5% (vol/vol) inhibited K+-stimulated paranitrophenyl phosphatase activity of intact PC, which correlated with inhibition of basal and histamine-stimulated aminopyrine uptake ratio by PC and FG. NMR is a sensitive, noninvasive probe to show ethanol-induced changes in intact PC lipid membrane organization without altering ultrastructural morphology.

Purification and partial characterization of the (H+,K+)-transporting adenosinetriphosphatase from fundic mucosa

The microsomal (H+,K+)-ATPase systems from dog and pig fundic mucosa were purified to homogeneity and partially characterized. The method involves sodium dodecyl sulfate (SDS) (0.033% w/v) extraction of the microsomal non-ATPase proteins under appropriate conditions followed by sucrose density gradient centrifugation. Two distinct membrane bands of low (buoyant density = 1.08 g/mL) and high (buoyant density = 1.114 g/mL) densities having distinct enzymatic and chemical composition were harvested. The low-density membrane was highly enriched in Mg2+- or Ca2+-stimulated ATPase and 5'-nucleotidase activities but totally devoid of (H+,K+)-ATPase and K+-p-nitrophenylphosphatase activities. The latter two activities were found exclusively in the high-density membrane. SDS-polyacrylamide gel electrophoresis revealed the high-density membranes to consist primarily of a major 100-kilodalton (kDa) protein and a minor 85-kDa glycoprotein, the former being the catalytic subunit of the (H+,K+)-ATPase. The amino acid composition of the pure dog (H+,K+)-ATPase revealed close similarities with that from pig. The N-terminal amino acid was identified to be lysine as the sole residue. Similar to the high-density membrane-associated pure (H+,K+)-ATPase, the low-density membranes containing high Mg2+-ATPase activity also contained a 100-kDa peptide and a 85-kDa glycopeptide in addition to numerous low molecular weight peptides. Also, similar to the pure (H+,K+)-ATPase, the Mg2+-ATPase-rich fraction produced an E approximately P unstable to hydroxylamine and partially (about 25%) sensitive to K+ but having a slow turnover. The levels of E approximately P produced by the pure (H+,K+)-ATPase- and Mg2+-ATPase-rich fractions were 1400 and 178 pmol/mg of protein, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Characteristics of a pure endogenous activator of the gastric H+,K+-ATPase system. Evaluation of the role as a possible intracellular regulator

An endogenous activator capable of stimulating the gastric H+,K+-ATPase activity has been purified to homogeneity from dog and pig gastric cells and found to be a dimer of two identical 40-kDa subunits in the active state. Identical nature of the activator monomers was revealed by the detection of lysine as the sole N-terminal amino acid. The activator from one species can stimulate the H+,K+-ATPase from another species and vice versa. Such cross-activation is consistent with the striking similarities in the amino acid composition between the two species, suggesting considerable homology in the activator molecules from different species. The activator exhibited several unique features during modulation of the H+,K+-ATPase reaction. It appreciably enhances affinity of the H+,K+-ATPase for K+, known to increase turnover of the enzyme. To complement this K+ affinity, the activator also enhances ability of the H+,K+-ATPase to generate more transition state (E*.ATP) complex by increasing the entropy of activation (delta S++) of the system as revealed from an Arrhenius plot of the data on temperature activation. In addition, the activator shows both positive cooperativity and strong inhibition, depending on its concentration. Thus, up to the ratio of the H+,K+-ATPase and activator of about 1:2 (on the protein basis), the activator shows sigmoidal activation (Hill coefficient = 4.5), but beyond such concentration a strong inhibition was observed. Finally, Ca2+ at low (2-4 microM) concentration strongly inhibits the activator-stimulated H+,K+-ATPase. It is proposed that the activator may be acting as a link in the signal transducing cascade system between the intracellular second messenger (Ca2+) and the physiological response (gastric H+ transport).