Outbreak of viral hepatitis B in a rural community in India linked to inadequately sterilized needles and syringes

In India, virtually all outbreaks of viral hepatitis are considered to be due to faeco-orally transmitted hepatitis E virus. Recently, a cluster of 15 cases of viral hepatitis B was found in three villages in Gujarat State. The cases were epidemiologically linked to the use of inadequately sterilized needles and syringes by a local unqualified medical practitioner. The outbreak evolved slowly over a period of 3 months and was marked by a high case fatality rate (46.7%), probably because of concurrent infection with hepatitis D virus (HDV) or sexually transmitted infections. But for the many fatalities within 2-3 weeks of the onset of illness, the outbreak would have gone unnoticed. The findings emphasize the importance of inadequately sterilized needles and syringes in the transmission of viral hepatitis B in India, the need to strengthen the routine surveillance system, and to organize an education campaign targeting all health care workers including private practitioners, especially those working in rural areas, as well as the public at large, to take all possible measures to prevent this often fatal infection.

A study on opportunistic enteric parasites in 80 HIV seropositive patients

AIDS is characteristically associated with several opportunistic enteric protozoal infestations that cause chronic and at times fatal diarrhoeas. A study is undertaken to isolated opportunistic enteric parasites in 80 HIV seropositive patients. An attempt is made to correlate and signify the presence of coexistent oral candidosis and enteric pathogens.

Newer concepts and approaches to neonatal brain asphyxia

The asphyxial injury to neonate brain seems to be mediated through a cascade of biochemical events during ischaemia--reperfusion which includes excitatory amino acids, free radicals and accelerated programmed cell death (Apoptosis). The diagnosis of asphyxia requires rigorous approach based on background clinical information, certain diagnostic tests and exclusion of alternative diagnosis which may have similar clinical presentation. The treatment currently employed for the management of birth asphyxia controversial and requires critical appraisal. The future strategies for management include a number of approaches based on putative mechanism for asphyxial brain injury but they are still being evaluated as research and should not be used for clinical purposes in human newborns as yet.

Effects of microinjections of cholecystokinin and neurotensin into lateral hypothalamus and ventral mesencephalon on intracranial self-stimulation

Changes in intracranial self-stimulation (ICSS) evoked from ventral tegmental area-substantia nigra (VTA-SN) and lateral hypothalamus-medial forebrain bundle (LH-MFB) before and after microinjections of sulfated cholecystokinin octapeptide (CCK-8S) and unsulfated cholecystokinin (CCK-8US), neurotensin tridecapeptide ([D-Tyr11]NT(1-13) or [DTrp11]NT(1-13)) into either VTA-SN or LH-MFB were assessed. The current intensity was fixed at a level to obtain 60-70% of the maximal asymptotic rate. CCK-8S (0.10 microg/0.5 microl and 0.25 microg/0.5 microl) into VTA-SN resulted in dose-dependent decreases in VTA-SN ICSS of 38-42% and 78-92%, respectively, without affecting the ICSS of LH-MFB. Similar doses of CCK-8S injected into LH-MFB changed neither LH-MFB ICSS nor VTA-SN ICSS. CCK-8Us injected into VTA-SN or LH-MFB had no effect on ICSS in either site. Intra-VTA-SN injections of the neurotensin-1 (NT1) receptor agonist [DTyr11]NT(1-13) and the NT1 receptor antagonist [D-Trp11]NT(1-13) at doses of 5 microg/0.5 microl and 10 microg/0.5 microl decreased VTA-SN ICSS. NT1 receptor agonist and antagonist injections did not alter LH-MFB ICSS in any significant manner. Similar injections of these peptides into LH-MFB did not change the responding rates for LH-MFB ICSS or VTA-SN ICSS. Increasing the current intensity reversed the inhibitory effect of CCK-8S and [D-Trp11]NT(1-13) on VTA-SN ICSS and restored basal preinjection rates of responding. These results suggest that CCK(A) and NT1 receptor mechanisms in the ventral tegmentum in association with dopamine neurotransmission may be important in mediating the rewarding effects of VTA-SN ICSS but not LH-MFB ICSS.

Assessment of iodine deficiency in selected blocks of east and west Champaran districts of Bihar

OBJECTIVE

A survey conducted in 1964 reported a goitre prevalence of 40.3% in East and West Champaran districts of Bihar. No recent survey has been documented on the prevalence of iodine deficiency in these districts. The present study was therefore undertaken (i) to assess the prevalence of IDD in these districts, and (ii) to estimate the iodine content of salt consumed by population.

METHODOLOGY

In each district, one block was selected. In each block more than 630 children in the age group of 6-12 years were included in the study and were clinically examined. Urine samples were collected from 261 children and were analyzed using standard laboratory procedures. A total of 456 salt samples were collected from children and 35 from traders from the two districts and analyzed using the standard iodometric titration method.

RESULTS

The total goiter prevalence was 11.6%. The percentage of children with < 2, 2.0-4.9, 5.0-9.9 and > or = 10 mcg/dl of urinary iodine excretion level were 12.3, 13.4, 23.4 and 51.0, respectively. The median urinary iodine excretion of the children was 10.0 mcg/dl. None of the families were consuming salt with a nil iodine content and about 29.3%, were consuming salt with less than 15 ppm of iodine. Of the 35 salt samples collected from traders, all had iodine and about 17% had less than 15 ppm of iodine.

CONCLUSION

The study stresses the need for strengthening the existing system of monitoring of quality of salt being provided in the East and West Champaran districts by Government of Bihar.

Dietary and physiological studies to investigate the relationship between calcium and magnesium signalling in the mammalian myocardium

This study employs both dietary and physiological studies to investigate the relationship between calcium (Ca2+) and magnesium (Mg2+) signalling in the mammalian myocardium. Rats maintained on a low Mg2+ diet (LMD; 39 mg Kg-1 Mg2+ in food) consumed less food and grew more slowly than control rats fed on a control Mg2+ diet (CMD; 500 mg Kg-1 Mg2+ in food). The Mg2+ contents of the heart and plasma were 85 +/- 3% and 34 +/- 6.5%, respectively relative to the control group. In contrast, Ca2+ contents in the heart and plasma were 177 +/- 5% and 95 +/- 3%. The levels of potassium (K+) was raised in the plasma (129 +/- 16%) and slightly decreased in the heart (88 +/- 6%) compared to CMD. Similarly, sodium (Na+) contents were slightly higher in the heart and lowered in the plasma of low Mg2+ diet rats compared to control Mg2+ diet rat. Perfusion of the isolated Langendorff's rat heart with a physiological salt solution containing low concentrations (0-0.6 mM) of extracellular magnesium [Mg2+]o resulted in a small transient increase in the amplitude of contraction compared to control [Mg2+]o (1.2 mM). In contrast, elevated [Mg2+]o (2-7.2 mM) caused a marked and progressive decrease in contractile force compared to control. In isolated ventricular myocytes the L-type Ca2+ current (ICa,L) was significantly (p < 0.001) attenuated in cells dialysed with 7.1 mM Mg2+ compared to cells dialysed with 2.9 microM Mg2+. The results indicate that hypomagnesemia is associated with decreased levels of Mg2+ and elevated levels of Ca2+ in the heart and moreover, internal Mg2+ is able to modulate the Ca2+ current through the L-type Ca2+ channel which in turn may be involved with the regulation of contractile force in the heart.

Piperine inhibits aflatoxin B1-induced cytotoxicity and genotoxicity in V79 Chinese hamster cells genetically engineered to express rat cytochrome P4502B1

We have investigated the potential of piperine for inhibiting the activity of cytochrome P4502B1 and protecting against aflatoxin B1 (AFB1) in V79MZr2B1 (r2B1) cells, i.e. V79 Chinese hamster cells engineered for the expression of rat CYP4502B1. The cells were found to contain high activities of 7-methoxycoumarin demethylase (MOCD). Piperine inhibited MOCD in preparations of r2B1 cells with an IC50 of approximately 10 microM. The cells in culture dealkylated 7-methoxycoumarin (MOC) to 7-OH-coumarin linearly, at least for 12 h, where piperine produced concentration-dependent inhibition with IC50 < 30 microM. The time required for maximal inhibition was approximately 8 h with both 30 and 60 microM concentrations of piperine used. AFB1 at 0.1-20 microM caused a concentration dependent decrease in the amount of DNA and an increase in the formation of micronuclei (MN). The mycotoxin at 10 microM reduced DNA by approximately 30% and increased MN appearance by 20-fold against the background level of 7 MN per 500 nuclei. Piperine at 60 microM completely counteracted cytotoxicity and formation of MN by 10 microM AFB1 and reduced the toxic effects of 20 microM AFB1 by > 50%. The results suggest that: (i) Piperine is a potent inhibitor of rat CYP4502B1 activity; (ii) AFB1 is activated by r2B1 cells to cytotoxic and genotoxic metabolites; and (iii) piperine counteracts CYP4502B1 mediated toxicity of AFB1 in the cells and might, therefore, offer a potent chemopreventive effect against procarcinogens activated by CYP4502B1.

Effects of extracellular Mg2+ concentration on intracellular signalling and acid secretion in rat gastric parietal cells

In the present study, the effects of extracellular magnesium concentration ([Mg2+]ex) on stimulus-secretion coupling processes were investigated in rat gastric parietal cells in vitro. Extracellular magnesium reduction resulted in (1) an increase of basal intracellular free calcium concentration ([Ca2+]in), (2) an enhancement of both carbachol and thapsigargin-induced calcium responses, (3) an improved filling state of intracellular calcium stores, (4) an increase of both basal and carbachol-induced acid secretion, whereas intracellular adenosine 3',5'-cyclic monophosphate (cyclicAMP) levels and histamine stimulated acid secretion were not affected. The effects of high [Mg2+]ex were opposite to the described results, except that high [Mg2+]ex was able to decrease significantly histamine-stimulated cyclicAMP levels and acid secretion. These findings indicate a modulatory role of [Mg2+]ex on the intracellular signalling processes and acid secretory properties in rat parietal cells. These effects seemed to be mediated by regulating (1) calcium loading capacity of intracellular stores, (2) the permeability of the calcium influx pathway, and (3) the formation of cyclicAMP.

Trace metals and metalloenzymes in placenta after oral administration of lead acetate

The present study was carried out to find the effects of Pb acetate (10-50 mg/kg body wt) after oral administration on: 1. The distribution of elements, such as Fe, Cu, Zn, and Mn; 2. The activity of 6-amino levulenic acid dehydratase (delta-ALAD) and alkaline phosphatase (PAP); and 3. On the level of reduced glutathione (GSH) in murine placenta. Pb toxicity expressed on a dry-wt basis was reflected in terms of deficiency of delta-ALAD and PAP and enhanced content of GSH. Analysis of trace elements following Pb exposure showed low levels of Mn and Cu. Although Fe composition of placenta remained within normal range with increasing load of endogeneous Pb, Zn decline was not consistent after oral feeding of Pb acetate. Deficiency of PAP after Pb exposure did not correlate with the endogeneous levels of Pb or Zn therein, but correlated with endogeneous levels of Mn. Placental deficiencies of Cu and Mn have been related to the disturbed placental functions by Pb accumulation.

Transplacental dilution of tetanus antitoxins in Delhi

Maternal blood-cord samples from 171 women of middle socio-economic status who had been administered at least two doses of tetanus toxoid (TT), were assayed for tetanus antitoxins by passive haemagglutination (PHA) test. All the mother as well as cord samples had antitoxin titres > or = 0.015IU/ml, the generally accepted minimal protective level; 98 per cent of the mothers and 97 per cent of the newborns had levels > or = 0.125IU/ml. Transplacental dilution was observed in 45 per cent of the samples; the cord/maternal antitoxin ratio (C/M) of geometric mean titre (GMT) was found to be 0.72. The C/M ratio was not affected by the maternal age, parity, birth weight, and number of TT doses administered to mother. The study showed that tetanus antitoxins were diluted on the fetal side of circulation, but the protective levels of antitoxins were achieved in all the newborns as the mothers had received at least two doses of TT before delivery.

Effect of penetration enhancers and iontophoresis on the ultrastructure and cholecystokinin-8 permeability through porcine skin

The present study explores the effect of chemical penetration enhancers and iontophoresis on the in vitro permeability of cholecystokinin-8 (CCK-8) through porcine epidermis and on the ultrastructural changes in stratum corneum as observed by transmission electron microscopy (TEM). Enhancer [i.e., ethanol (EtOH), and 10% oleic acid in combination with ethanol (OA/EtOH)] pretreatment significantly increased (p < 0.01) the permeability coefficient of CCK-8 in comparison with the control (pretreated epidermis without enhancer). Iontophoresis further increased the permeability of CCK-8 (p < 0.01) through the enhancer-pretreated epidermis in comparison with the control. These results showed the synergistic effect of iontophoresis and enhancers such as OA/EtOH that provides an additional driving force to maintain and control the target flux of CCK-8. The ultrastructure of stratum corneum treated with ethanol demonstrated a loss of structural components in the superficial stratum corneum cell layers. OA/EtOH transformed the highly compact cells of stratum corneum into a looser network of filaments, creating an increased free volume and greater intracellular surface area. Treatment of stratum corneum with OA/EtOH followed by iontophoresis resulted in further swelling of stratum corneum cell layers. In conclusion, OA/EtOH in combination with iontophoresis increased the permeability of CCK-8 by loosening and swelling of stratum corneum cell layers.

Solid-phase extraction of THC metabolite from urine using the Empore disk cartridge prior to analysis by GC-MS

The Empore disk cartridges (C18) were evaluated for sample preparation in the gas chromatography-mass spectrometry confirmational assay for the 11-nor-9-carboxy-delta 9-tetrahydro-cannabinol (THCCOOH) metabolite. The performance of the Empore disk cartridges, determined by the recovery, precision, limit of detection (LOD), and limit of quantitation (LOQ) of the assay was comparable with the performance of a widely used solid-phase extraction cartridge (Spec C18 cartridges) and the traditional liquid-liquid extraction technique. The Empore disk cartridges showed an average recovery of 89% at low concentrations of 6 ng/mL of the THC metabolite spiked into urine. The recovery was consistent across three different lots of Empore disk cartridges. The within-run precision of the assay at a concentration of 18 ng/mL had a coefficient of variation of 2%, and the LOD and LOQ were determined to be 1 ng/mL.

Dietary fat and colon cancer: modulation of cyclooxygenase-2 by types and amount of dietary fat during the postinitiation stage of colon carcinogenesis

Several epidemiological and experimental studies have indicated a strong relationship between different types of dietary fats and risk of colon cancer. However, the modulating effects of these nutritional factors at the molecular level are not fully elucidated. It has been documented that the modulation of tumorigenesis is associated with changes in the levels of prostaglandins production. To provide an understanding of the mechanism(s) of dietary fat-induced modulation of colon tumor development, we have analyzed the expression of cyclooxygenase (COX), an enzyme that catalyzes the metabolism of omega-3 and omega-6 polyunsaturated fatty acids in a critical step in prostaglandin biosynthesis. Male F344 rats were fed the semipurified AIN-76A diet containing low-fat corn oil and were s.c. injected azoxymethane (AOM) dissolved in normal saline at a dose rate of 15 mg/kg of body weight, once weekly, for 2 weeks. Vehicle controls received s.c. equal volumes of normal saline. One day after the second AOM or saline injection, rats intended to receive experimental diets were provided high-fat corn oil (HFCO) or high-fat fish oil (HFFO) mixed in semipurified AIN-76A diet, and the remaining rats continued to receive the low-fat corn oil diet. Animals were sacrificed 1, 12, or 36 weeks after the last AOM or saline injection, and their colonic mucosa, as well as the grossly visible colon tumors from rats sacrificed 36 weeks after the last AOM injection, were analyzed for the expression levels of COX-1 and COX-2. The results indicate that AOM induced increasingly high levels of COX-2 expression with advancing stages of colon tumorigenesis. HFCO further enhanced the AOM-induced COX-2 expression. In contrast, HFFO ingestion resulted in a significant decrease in COX-2 expression both in the colonic mucosa and in tumors. These results correlate with increased incidence and multiplicity of grossly visible colon tumors in AOM-treated animals that were fed the HFCO diet versus decreased tumor incidence and lower tumor multiplicity in animals that were fed the HFFO diet. No significant differences were observed in expression levels of COX-1. The data suggest that HFCO may promote colon tumorigenesis by up-regulating the COX-2 expression, whereas HFFO may exert its antitumor effect by inhibiting the COX-2 expression.

RNA-mediated regulation of Receptor-Ck gene in human platelets

The study addressed to understand the regulation of Receptor-'Ck' gene at the translational level revealed that exogenous cholesterol has the inherent capacity to regulate the endogenous synthesis of Receptor-'Ck' by initiating intracellular targeting of the Receptor-'Ck' to the mRNP pool within human platelets and this effect could be reversed when the platelets were incubated with cholesterol coupled with either dB cAMP or dB cGMP. Based upon these observations, we propose that Receptor-'Ck' initiated signalling, which involves second messengers like PA, cAMP and cGMP, may be responsible for the autoregulation of Receptor-'Ck' gene expression at the translational level.

Pharmacokinetics and pharmacodynamics of 15-deoxyspergualin in a canine renal allograft model of local immunosuppression

Local immunosuppression is based on the rationale that one can simultaneously prevent rejection and reduce systemic side effects by administering appropriately chosen immunosuppressive agents directly into the allograft. We utilized a mongrel canine renal transplant model with a programmable, implantable pump/catheter system to estimate the first-pass extraction of 15-deoxyspergualin (DSG) during renal artery infusion and to compare the efficacy and toxicity of continuous intraarterial (ia) versus intravenous (iv) DSG delivery. Six autotransplanted dogs were given DSG by both iv bolus (1 mg/kg) and ia infusion (1.0 mg/kg/d). DSG was administered to allograft recipients by continuous ia infusion at 0.5 (n = 11) and 0.75 (n = 8) mg/kg/day and by continuous iv infusion at 0.5 (n = 12) and 0.75 (n = 6) mg/kg/day. Mean +/- SD elimination half-life was 0.6 +/- 0.1 hr, and the transplanted kidney removed as much as 55-88% (mean 66%) of locally infused DSG. When compared with untreated controls [mean survival time (MST) = 8 days], low-dose (0. 5 mg/kg/day) DSG produced a significant antirejection effect when given ia (MST = 12 days; P = 0.04) but not iv (MST = 9 days; P = 0. 09), with equivalent overall mean drug levels during normal renal function. However, two of the four longest-surviving animals in the ia group died from severe systemic toxicity, manifested by anorexia, diarrhea, leukopenia, and sepsis. High-dose (0.75 mg/kg/day) DSG significantly prolonged survival via both local (MST = 12 days; P = 0.04) and systemic (MST = 11 days; P = 0.02) routes, but half of the iv-treated dogs died from, and four of the longer-surviving ia-treated animals manifested signs of, systemic toxicity, with significantly higher mean drug levels in the iv group. DSG significantly suppressed vascular rejection at both doses when administered locally and systemically, dose-dependently affected the severity of tubulointerstitial rejection and graft edema, and was not nephrotoxic. Our autotransplant pharmacokinetic data overestimated the allografted kidney's ability to extract DSG during local infusion of slightly lower, but immunosuppressive, doses, so that death from systemic toxicity was not prevented and a direct survival benefit of ia vs iv therapy was not realized. Local DSG administration might be combined with other immunosuppressants to therapeutic advantage.

Retinoblastoma (pRb) protein immunoexpression in colorectal cancer

The level of expression of the cell cycle regulatory proteins is an important facet in determining the malignant state. Fifty consecutive colectomy specimens of colorectal carcinoma in patients over 50 years of age, and 25 cases in patients under 30 years, were examined to ascertain retinoblastoma protein expression and to relate this to clinicopathological features. Retinoblastoma protein (pRb) staining was more intense in well differentiated, low stage carcinomas in the over 50 age group (p < 0.001). On the other hand, in the under 30 age group, pRb staining was seen in all tumours grades and stages. No statistical significance was noted with other clinical or pathological features in both age groups.

A study on interrelationship of 60 HIV positive cases with coexistent oral candidosis and tuberculosis

Sixty HIV seropositive cases studied of inter-relationship of coexistent infections with tuberculosis and oral candidosis. Presence of oral candidosis either symptomatic/asymptomatic as revealed on microbiological studies have been recorded and the significance discussed. Presence of oral candidosis apparent of nonapparent with heavy growth, yield on culture in HIV seropositive cases could be considered a pointer of conversion of HIV infection to a disease. This observation needs further evaluation. Relevant literature reviewed briefly.

Multiple myeloma complicating HIV-infection. A case report

A case of multiple myeloma associated with HIV disease and hepatosplenomegaly presented to us as pyrexia of unknown origin, is reported. Because of paucity of such cases in the literature, the case is dealt in detail and the literature reviewed briefly.

Dopamine receptor sub-types involvement in nucleus accumbens and ventral tegmentum but not in medial prefrontal cortex: on self-stimulation of lateral hypothalamus and ventral mesencephalon

The involvement of different sub-types of dopamine receptors in the electrical self-stimulation behaviour was investigated using DA receptor subtype specific agonists viz R(+) SKF 38393 and LY 171555 (quinipirole). Rats were chronically implanted with bipolar electrodes in lateral hypothalamus-medial forebrain bundles (LH-MFB) and ventral tegmental area-substantia nigra (VTA-SN) or guide cannula in nucleus accumbens (nACB) or medial prefrontal cortex (mPFRCx) or cannula-cum-electrode in VTA-SN. Combining these, it was possible to inject a given receptor ligand in either nACB or mPFRCx or VTA-SN and assess the changes in intracranial self-stimulation (ICSS) of LH-MFB or VTA-SN. The experimental subjects were trained to press a pedal to obtain 0.25 s trains of cathodal rectangular pulses of 0.1 ms pulse duration (for LH-MFB electrode) or 0.3 ms pulse duration (for VTA-SN electrode). The rate-frequency curve for each subject and each placement were obtained in order to determine M50 (50% of maximum asymptotic response rate). Microinjection of SKF 38393 (a D1 agonist) or LY 171555 (a D2 agonist) into nACB caused facilitatory and suppressive effects on the ICSS of VTA-SN and LH-MFB respectively. On the contrary, intra VTA-SN injection of 10 micrograms/0.5 microliter of SKF 38393 or of LY 171555, reduced its ICSS to half as compared to vehicle injections. Under the effect of these injections, there was no change in the ICSS of LH-MFB. The combined administration of SKF 38393 (5 micrograms) and LY 171555 (10 micrograms) into nACB produced suppression of ICSS of VTA-SN to greater extent than the LY 171555 (10 micrograms/0.5 microliter). This indicates that coactivation of D1 and D2 leads to suppression of ICSS of VTA-SN. The activation of D1 receptors in nACB facilitates the ICSS of both VTA-SN and LH-MFB by increasing the reinforcement and/locomotor activity, while the activation of D2 receptors in it has opposite effect. The coactivation of D1 and D2 receptors in VTA-SN leads to the suppression of ICSS of both VTA-SN and LH-MFB. Similar injections of these receptor ligands into mPFRCx did not alter the ICSS of either LH-MFB or VTA-SN. The pre- or post-synaptic DA receptors of mPFRCx do not appear to influence the ICSS of either VTA-SN or LH-MFB in any significant manner.

Intact mirror-tracing and impaired rotary-pursuit skill learning in patients with Huntington's disease: evidence for dissociable memory systems in skill learning

Skill learning in early-stage Huntington's disease (HD) patients was compared with that of normal controls on 2 perceptual-motor tasks, rotary pursuit and mirror tracing. HD patients demonstrated a dissociation between impaired rotary-pursuit and intact mirror-tracing skill learning. These results suggest that different forms of perceptual-motor skill learning are mediated by separable neural circuits. A striatal memory system may be essential for sequence or open-loop skill learning but not for skills that involve the closed-loop learning of novel visual-response mappings. It is hypothesized that working memory deficits in HD resulting from frontostriatal damage may account broadly for intact and impaired long-term learning and memory in HD patients.

Differential biochemical response of freshly isolated rat hepatocytes to paracetamol, carbon tetrachloride and D-galactosamine toxicity

Differential response of freshly isolated rat hepatocytes to paracetamol (acetaminophen, AAP), carbon tetrachloride (CCl4) and D-galactosamine (GalN) was examined. The viability of the cells in suspension culture was not altered for 4 hr when incubated in Hank's balanced salt solution (HBSS) supplemented with 4.2 mM NaHCO3, 10 mM HEPES buffer and 0.5% bovine serum albumin. AAP induced time and dose dependent depletion of GSH as an early manifestation of AAP toxicity. Hepatocytes exposed to AAP exhibited lower lactate dehydrogenase (LDH) activity released into the medium than in controls. This was due to the interaction of a reactive metabolite of AAP, i. e. N-acetyl p-benzoquinoneimine (NAPQI) with cell proteins. Hepatocytes isolated from rats pretreated with 3-methylcholanthrene expressed higher sensitivity to AAP toxicity at least by a factor of 5. Furthermore, AAP-induced toxicity was not found to be related to any lipoperoxidative stress. CCl4 on the other hand elicited a highly lipoperoxidative response in hepatocytes and consequent leakage of cellular enzymes with lengths of incubation. Again the sensitivity of the response to CCl4 was enhanced remarkably in hepatocytes isolated from phenobarbital- pretreated rats; LDH leakage increased by 3-fold and thio-barbituric acid reactive substances by 25-fold. Unlike the two toxicants, galactosamine depleted UDP-glucuronic acid in a concentration and time-related manners. The differential biochemical response of hepatocytes to three hepatotoxicants investigated may prove useful as rapid in vitro screen for selection of compounds of hepatoprotective potentials.

Silymarin mediated differential modulation of toxicity induced by carbon tetrachloride, paracetamol and D-galactosamine in freshly isolated rat hepatocytes

Influence of silymarin on the modulation of hepatotoxicity induced by carbon tetrachloride (CCl4), paracetamol (AAP) and D-galactosamine (GalN) was examined in freshly isolated rat hepatocytes in suspension culture. While the three hepatotoxicants produced differential biochemical response, the flavone was able to restore biochemical alterations only in hepatocytes exposed to CCl4 and AAP induced toxicity. Silymarin at 0.4 mM was able to counteract lipid peroxidation and enzyme leakage induced by 3 mM CCl4 The flavone also offered protection by more than 60% in hepatocytes isolated from PB pre-treated rats where CCl4 at 2 mM produced enhanced toxicity over hepatocytes isolated from untreated control rats. Similarly, the flavone protected AAP-induced GSH depletion by more than 75% in hepatocytes isolated from untreated and 3-methylcholanthrene treated rats. However, instead of protecting GalN-induced depletion of UDP-glucuronic acid in hepatocytes, the flavone itself reduced the nucleotide content very rapidly compared to GalN, the later exerted time dependent effect. Silymarin at 0.4 mM reduced UDPGA by more than 60%. The results suggested that freshly isolated hepatocytes in suspension culture offer a simple and convenient method for evaluation of pharmaceutical agents of antihepatotxic potentials against various hepatotoxicants.

Control of porcine lacrimal gland secretion by non-cholinergic, non-adrenergic nerves: effects of electrical field stimulation, VIP and NPY

This study employs the technique of electrical field stimulation (EFS) to characterise the effects of endogenous neurotransmitters on protein secretion in the in vitro pig lacrimal gland. The effects of exogenous applications of neurotransmitters on protein output and peroxidase secretion were also investigated for comparative purposes. EFS evoked frequency-dependent (5-20 Hz) increases in protein secretion. The EFS-evoked protein output was abolished with the nerve blocking drug tetrodotoxin (10(-6) M, TTX). Elevated potassium (100 mM KCl) can stimulate protein output in the presence of TTX. Exogenous application of either acetylcholine (ACh, 10(-9)-10(-4) M) or noradrenaline (NA, 10(-8)-10(-4) M) can also result in protein secretion, but they have no detectable effect on peroxidase secretion. In the presence of the cholinergic antagonist, atropine (10(-5) M) the EFS-induced protein output was reduced but not abolished. This atropine-resistant and non-cholinergic nerve-mediated component was further reduced in the combined presence of atropine, phentolamine, and propranolol (all 10(-5) M). When vasoactive intestinal polypeptide (VIP) receptor antagonist (10(-6) M [4-Cl-D-Phe6-Leu17]-VIP) was combined with the cholinergic and adrenergic antagonists, EFS caused a small but detectable increase in protein output. Exogenous application of either 10(-9) M VIP or 10(-9) M neuropeptide-Y (NPY) resulted in protein secretion. Combination of both VIP and NPY only induced an additive effect on protein output. Theophylline (10(-4) M), a phosphodiesterase inhibitor, evoked a small increase in protein output and had no significant effect on the secretory responses elicited by either VIP or NPY. In contrast, theophylline potentiated the non-cholinergic, non-adrenergic EFS-induced protein secretion. The results indicate that protein secretion from the porcine lacrimal gland may be controlled by cholinergic, adrenergic and non-cholinergic, non-adrenergic nerves. The peptidergic neurotransmitters may be VIP and other related neuropeptide(s). In addition to these neurophysiological studies, our results confirm previous findings that the porcine lacrimal nerves contain abundant quantity of NPY and VIP.