Various protocols of cell culture antirabies vaccines.
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Cells, Cultured↗
Biomedical subjects
T K Ghosh
Publications and source records attributed to T K Ghosh.
In-vitro assessment of a matrix system of levobunolol.
In order to study the feasibility of systemic delivery of levobunolol transdermally, a matrix-type delivery system was fabricated using a silicone elastomer. The relationship between loading dose and skin permeation rate was evaluated in-vitro using hairless mouse skin mounted on the stirred receptor compartment of the Keshary-Chien glass diffusion cell maintained at 37 degrees C. The concentration of levobunolol in the receptor compartment was determined by HPLC. A similar study without using the skin was carried out to determine the effect of loading dose on the release of levobunolol from discs. It was observed that the release of drug from disc followed a matrix-diffusion controlled (Q) vs square root of time relationship at different loading doses. In contrast, the results of skin permeation of levobunolol from transdermal discs containing different loading doses showed a linear Q vs time relationship indicating a constant zero order skin permeation rate at each loading dose. Skin permeation of levobunolol appeared to reach a plateau at a 5% (w/w) loading dose in the disc indicating the attainment of equilibrium concentration of levobunolol in the skin.
Administration, Cutaneous↗
Function and organization of the inositol 1,4,5-trisphosphate-sensitive calcium pool.
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Animals↗
Persistent intracellular calcium pool depletion by thapsigargin and its influence on cell growth.
The intracellular Ca2+ pump inhibitor, thapsigargin, added to DDT1MF-2 smooth muscle cells in culture, irreversibly inhibited accumulation of Ca2+ within cells, permanently emptied the inositol 1,4,5-trisphosphate (InsP3)-sensitive Ca2+ pool, and simultaneously induced profound alteration of cell growth. After only a brief (30-min) treatment of cultured cells with 3 microM thapsigargin followed by extensive washing, the total releasable InsP3-sensitive Ca2+ pool remained entirely empty, even after 7 days of culture without thapsigargin. After thapsigargin treatment, cells retained viability, usual morphology, and normal mitochondrial function. Despite the otherwise normal appearance and function of thapsigargin-treated cells, cell division was completely blocked by thapsigargin. DNA synthesis was completely inhibited when thapsigargin was added immediately after passaging, but was suppressed only slowly (4-6 h) when added to rapidly synthesizing cells (24 h after passaging). Protein synthesis was reduced by approximately 70% in thapsigargin-treated cells. The sensitivity of thapsigargin-mediated inhibition of cell division, DNA synthesis, protein synthesis, and Ca(2+)-pumping activity were all similar with the EC50 values for thapsigargin in each case being close to 10 nM. Upon application to DDT1MF-2 cells, thapsigargin transiently increased resting cytosolic Ca2+ (0.15 microM) to a peak of 0.3 microM within 50 s; thereafter, free Ca2+ declined to 0.2 microM by 150 s and continued to slowly decline toward resting levels. Cells treated with thapsigargin for 1-72 h in culture displayed normal resting cytosolic Ca2+ levels. However, application of thapsigargin or epinephrine to such cells resulted in no change in the intracellular Ca2+, indicating that the internal Ca2+ pool remained completely empty. These results suggest that emptying of Ca2+ from intracellular thapsigargin-sensitive Ca(2+)-pumping pools induces profound alteration of cell proliferation.
Animals↗
Identification of intracellular calcium pools. Selective modification by thapsigargin.
Recent studies have identified inositol 1,4,5-tris-phosphate(InsP3)-sensitive and -insensitive Ca2+ pools and a GTP-dependent mechanism that transfers Ca2+ between them. Here, the Ca2+ pump-inhibitory sesquiterpene lactone, thapsigargin, is shown to distinguish these two Ca2+ pools and identify a third Ca2+ pumping pool unresponsive to InsP3 or GTP. Using saponin-permeabilized DDT1MF-2 smooth muscle cells, approximately 75% of total intracellular ATP-dependent Ca2+ accumulation is blocked by thapsigargin with an IC50 of 30 nM. In contrast, 1 mM vanadate or 5 microM A23187 block 100% of Ca2+ accumulation. The thapsigargin-responsive Ca2+ pool corresponds exactly to that released by 10 microM InsP3 in the presence of 10 microM GTP. Indeed, addition of InsP3 with GTP has no effect on Ca2+ accumulated in the presence of 3 microM thapsigargin whereas A23187 releases all the remaining Ca2+. Added after maximal Ca2+ uptake, thapsigargin induces only slow Ca2+ release consistent with blockade of pumping activity. Unlike InsP3, the action of thapsigargin is entirely heparin insensitive. The large increment in Ca2+ uptake caused by 12 mM oxalate is completely reversed by thapsigargin, indicating that thapsigargin functions on an oxalate-permeable pool. Moreover, the still larger uptake induced by GTP in the presence of oxalate is also completely reversed by either thapsigargin or InsP3. The results indicate that thasigargin blocks Ca2+ uptake into two discrete pools: the InsP3-sensitive, oxalate-permeable Ca2+ pool and the InsP3-insensitive, oxalate-impermeable Ca2+ pool that can be "recruited" into the InsP3-sensitive pool by GTP-dependent Ca2+ translocation (Ghosh, T. K., Mullaney, J.M., Tarazi, F.I., and Gill, D.L. (1989) Nature 340, 236-239). Additionally, a third Ca2+ pool is defined, unreleasable by InsP3 or GTP, and containing a thapsigargin-insensitive Ca2+ pump.
Animals↗
Behavioral effects of ethanol inhalation in rats.
Behavioral effects of ethanol inhalation were studied on two fixed-ratio (FR) liquid-reinforced schedules and a continuous reinforcement (CRF) schedule intracranial self-stimulation (SS) in rats using the inhalational behavioral chamber designed in our laboratory. In the FR-24 schedule ethanol caused a decrease of reinforcement rate at 161 ppm and higher concentrations. In the FR-50 schedule decreases of the rate were observed at 102 ppm and 203 ppm. In the SS behavior ethanol produced a decrease in the rate of reinforcement at 603 ppm and higher concentrations. In rats of this schedule, blood ethanol concentrations were measured to be 393 micrograms/ml and 545 micrograms/ml after exposure to 600 ppm and 1200 ppm of ethanol respectively. Acute tolerance to ethanol was observed in these experiments, particularly in the FR-24 schedule. Thus ethanol inhalation could produce adequate blood concentrations so as to produce behavioral effects.
Administration, Inhalation↗
Effects of ethanol inhalation on EEG in rats.
Effects of ethanol on duration of stages of sleep-wake cycle and EEG power spectra were measured during a 2-h exposure in a dynamic inhalational chamber in rats. Rats were exposed to one of four graded concentrations (approx. 100, 400, 800 and 1600 ppm) of ethanol on different days. Ethanol was found to increase the duration of waking (W) with a decrease in duration of rapid eye movement (REM) sleep at 100 and 400 ppm. No effect was observed at 800 and 1600 ppm on the stages of sleep-wake cycle or at 100-1600 ppm on EEG power spectra from the somatosensory or visual cortices. Results indicate that ethanol administered by inhalation could produce arousal action at low doses, but did not have any effect on EEG power spectrum at the concentrations used.
Administration, Inhalation↗
Long term effect of diethylcarbamazine medicated common salt on bancroftian filariasis.
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Animals↗
Intracellular calcium release mediated by sphingosine derivatives generated in cells.
Soluble and hydrophobic lipid breakdown products have a variety of important signaling roles in cells. Here sphingoid bases derived in cells from sphingolipid breakdown are shown to have a potent and direct effect in mediating calcium release from intracellular stores. Sphingosine must be enzymically converted within the cell to a product believed to be sphingosine-1-phosphate, which thereafter effects calcium release from a pool including the inositol 1,4,5-trisphosphate-sensitive calcium pool. The sensitivity, molecular specificity, and reversibility of the effect on calcium movements closely parallel sphingoid base-mediated inhibition of protein kinase C. Generation of sphingoid bases in cells may activate a dual signaling pathway involving regulation of calcium and protein kinase C, comparable perhaps to the phosphatidylinositol and calcium signaling pathway.
Adenosine Diphosphate↗
Sensitivity of EEG in young rats to toluene exposure.
Effects of toluene on the electroencephalogram (EEG) and its power spectra were measured during a 2-hr exposure in a dynamic inhalational chamber in young rats (30-53 days old) and compared to those in adult rats (63-77 days old). Rats were exposed to one of the three concentrations [low (108-111 ppm), medium (160-163 ppm), and high (407-432 ppm)] of toluene on different days. In tests on sleep-wake cycle, in the young animals the duration of the wake stage (W) was increased with decreases of rapid eye movement (REM) and non-REM (NREM) sleep during hr 1 and hr 2 of exposure to the low concentration. These effects were marked at the medium and the high concentrations. In adult rats, at the low concentration the increase of W and the decrease of REM were observed only at hr 1; however, at medium and high concentrations these changes of W and REM sleep were marked along with a decrease of NREM. Comparison of the changes of duration of different states in rats of two age groups showed that there was a significant difference in the increase of W and the decrease of NREM sleep in young rats at hr 2 of exposure to low concentrations only compared to those in adult rats. Tested on power spectrum in young rats during REM sleep recorded from the visual cortex, the power of delta waves increased at the medium and high concentrations and that of theta wave decreased at the high concentration during hr 2 of exposure compared to the controls.(ABSTRACT TRUNCATED AT 250 WORDS)
Aging↗
Pharmacological actions of tentacle extract of the jellyfish, Acromitus rabanchatu, occurring in the Bay of Bengal.
Tentacle extract of A.rabanchatu, produced a fall of blood pressure in cat, rat and guinea pig. Hypotension produced in cat remained unantagonized by blockers of acetylcholine, histamine and 5-HT. On isolated guinea pig heart, the extract significantly reduced the rate and amplitude of contraction leading to irreversible cardiac arrest. In cats and rats, the respiratory rate and amplitude was decreased significantly and resulted in temporary apnoea. The extract also produced vasoconstriction in perfused rat hindquarter preparation and increased cutaneous capillary permeability. The extract produced contraction in several isolated smooth muscle preparations. Contraction on guinea pig ileum was partly antagonized by atropine and cyproheptadine. On isolated rat phrenic nerve diaphragm and chick biventer cervicis, the extract produced irreversible blockade of the electrical stimulation-induced twitch responses. Haemolytic and myonecrotic activity was exhibited by the extract. LD50 was found to be 7.7 mg/kg (iv, mice).
Animals↗
Glycaemic effects of tentacle extract of the jellyfish Acromitus rabanchatu (Annandale).
Tentacle extract of the common jellyfish A. rabanchatu, caused glycaemic alteration in fasting rabbits. Intravenous administration of the extract produced a significant rise followed by a significant fall in blood sugar level. Glucose tolerance in rabbits was also significantly increased. Extract-mediated hypoglycaemic response was fully abolished in alloxan diabetic rabbits. Preliminary separation on Sephadex G 50 indicated the hypoglycaemic factor to be a non-lethal protein of molecular weight less than 20 kDa. Heat treatment of extract and G 50 separated fraction P2 demonstrated total loss of hypoglycaemic activity.
Animals↗
Pharmacological and electrophysiological analysis of nicotine induced apnoea in the cat.
Intravenous nicotine (20-60 micrograms/kg) produced an initial brief apnoea followed by hyperventilation in anaesthetized cats. The apneic response to nicotine remained uneffected by atropine, by phentolamine or propranolol. Hexamethonium and guanethedine sulphate antagonized the apneic response. In bilateral vagotomized cats, nicotine failed to produce respiratory apnoea. Veratridine and phenyldiguanide produced apnoea similar to that produced by nicotine within 2-3 sec. administered intraartrially. Nicotine failed to stimulate pulmonary stretch receptors as did veratridine in artificially ventilated cats. The alpha and gamma motoneurone activity of inspiratory and expiratory muscles and the phrenic efferent activity were inhibited during apnoea. These inhibitions were absent in vagotomized cats. In conclusion, these results suggest that the nicotine induced apneic response is mediated through pulmonary vagal afferents, probably through J-receptors, which in turn inhibit the motoneurone activity involving the respiratory muscles.
Animals↗
GTP-activated communication between distinct inositol 1,4,5-trisphosphate-sensitive and -insensitive calcium pools.
Inositol 1,4,5-trisphosphate (InsP3) is an established mediator of intracellular Ca2+ signals but little is known of the nature and organization of Ca2+ regulatory organelles responsive to InsP3. Here we derive new information from the study of Ca2+ movements induced both by InsP3 and a specific GTP-activated Ca2+ translocation process. The latter mechanism is clearly distinct from that activated by InsP3 and may involve the translocation of Ca2+ between compartments without its release into the cytosol. This idea is supported by the fact that GTP activates Ca2+ movement into the InsP3-releasable pool. In the light of this evidence we postulated that there are two intracellular Ca2+ pools distinguishable by InsP3-sensitivity and oxalate-permeability, and that movement between them is activated by GTP. We report here direct evidence for the existence and separation of two distinct Ca2+-pumping compartments with properties coinciding with those predicted. Of these, the InsP3-sensitive Ca2+ pool is identified within a purified rough endoplasmic reticulum fraction, an observation consistent with recent InsP3 receptor-localization studies. Ca2+ translocation between pools may reflect function of a class of small GTP-binding proteins known to mediate interorganelle transfer in eukaryotic cells.
Animals↗
Effects of toluene exposure on the spontaneous cortical activity in rats.
Effects of toluene on the electroencephalogram (EEG) and its power spectra were measured during a 2-hr exposure in a dynamic inhalational chamber in rats. Rats were exposed to one of six graded concentrations (110.6, 162.5, 432, 676, 1558, 2730 ppm) of toluene on different days. It was found that the duration of waking (W) was increased with a decrease in duration of rapid eye movement (REM) sleep even at 110.6 ppm. Duration of nonrapid eye movement (NREM) sleep was decreased with an increase of W and a decrease of REM sleep at 162.5 ppm. Dose-related effects were noted in higher concentrations. The power of delta frequency band was increased with a decrease of theta frequency band power at hr 1 of exposure to 676 ppm during REM sleep recorded from the visual cortex. The power of theta frequency band was also decreased at hr 2 of exposure at 432 ppm. During W and NREM sleep power spectra were not changed significantly. Results indicate that the changes of EEG are a sensitive measure of the effects of toluene on the central nervous system (CNS).
Administration, Inhalation↗
Calcium signalling mechanisms in endoplasmic reticulum activated by inositol 1,4,5-trisphosphate and GTP.
Ca2+ signals are known to mediate an array of cellular functions including secretion, contraction, and conductivity changes. In spite of the obvious role of Ca2+ in signalling, the control of Ca2+ within cells is known to be a complex phenomenon involving a number of distinct active and passive transport systems functioning within different organelles. Inositol 1,4,5-trisphosphate (IP3) is now established as a central mediator of Ca2+ mobilization, and the endoplasmic reticulum (ER) has been considered to be the site of action of IP3. However, this role has been ascribed almost by default to the ER, based on the knowledge that IP3 functions to release Ca2+ from an intracellular, nonmitochondrial, Ca2+-pumping organelle. Our interest has been to ascertain by what mechanism IP3 activates Ca2+ movements, at what intracellular locations it functions, and how the size and replenishment of the IP3-sensitive Ca2+ pool occurs. During the course of such studies, another mechanism inducing profound movements of Ca2+ within cells was identified. This process is activated by a highly sensitive and specific guanine nucleotide regulatory mechanism, which, while inducing fluxes of Ca2+ that resemble the action of IP3 under certain conditions, has now been determined to involve a quite distinct mechanism. The characteristics of this mechanism are described below. Although involving a very different Ca2+ translocation process to that activated by IP3, several important conclusions have been drawn on the relationship between IP3- and GTP-activated Ca2+ movements leading us to believe that the latter may have a regulatory role in controlling the size and/or entry of Ca2+ into the IP3-sensitive Ca2+ pool.
Biological Transport↗
Detection of Wuchereria bancrofti antigen in serum and finger prick blood samples by enzyme immunoassay: field evaluation.
We have recently reported that a monoclonal antibody-based enzyme immunoassay for detection of filarial antigen in human serum is sensitive and specific for active infection with Wuchereria bancrofti. The present studies were undertaken to assess the feasibility of testing whole blood collected by finger prick in this assay. A preliminary study was performed to compare antigen test results obtained with whole blood, blood dried on filter paper, and serum. Results obtained with anticoagulated whole blood specimens agrees with serum results in 94 of 97 cases. All whole blood and serum specimens from 28 people with positive microfilaria smears were positive in the test. Filter paper blood specimens were less satisfactory because of decreased sensitivity and specificity. A population-based survey of 1009 persons was conducted in a village near Calicut, India, to evaluate the use of finger prick blood specimens for filarial antigen detection in field studies. Thirty-eight of 39 microfilaria carriers had positive antigen tests. In addition, 10.7% of amicrofilaremic endemic controls had positive tests. Additional studies are needed to test the hypothesis that filarial antigenemia in endemic controls indicates the presence of subclinical infection.
Adolescent↗
Epidemiology of bancroftian filariasis in a semi-urban community of Kerala State.
A community-based longitudinal study was initiated in 1983 in a semi-urban area, endemic for bancroftian filariasis to determine the incidence and prevalence, natural history and clinical pattern of filarial infection and also to study the impact of control measures on it. The base-line filariometric indices observed during the initial clinico-parasitological survey and entomological observations made during the first 12 months of this study are highlighted in this paper. 5.5 per cent of the examined population had microfilaraemia with average infestation of 8.1 per 20 cmm. The microfilaraemia found to have significant (P less than 0.001) relationship with age, but not with sex (P greater than 0.05). The filarial disease which had the prevalence of 3.6 per cent showed a significant (P less than 0.001) relationship to both age and sex. The youngest microfilaria (mf) carrier was of 2 years and with filarial swelling was of 6 years age. A significant (P less than 0.001) relationship of educational status and family size was observed with disease while it was non-significant (P greater than 0.05) with microfilaraemia. With the increase in per capita income of the individuals, a significant decrease in number of persons with microfilaraemia (P less than 0.01) as well as with disease (P less than 0.05) was noted. Culex quinquifasciatus, the vector for this infection was prevalent throughout the period of observation with highest density in September. Vector infection and infectivity rates ranged from 0 to 4.4 per cent and 0 to 2.2 per cent respectively.
Adolescent↗