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J Bhattacharya

Publications and source records attributed to J Bhattacharya.

At least 73 records · Page 4Linked to original sources
PubMed1994

Removal of albumin microinjected in rat lung perimicrovascular space.

We used a microinjection approach to assess hydraulic properties of lung perimicrovascular adventitia (interstitial cuff surrounding microvessels). Isolated blood-perfused rat lungs held at constant airway pressure were microscopically viewed to identify subpleural venules (20 microns diam). Venular adventitia were microinjected with 20 nl of fluorescent albumin (4 g/dl), and then adventitial fluorescence was quantified at the injection site by either photometery or imaging. Nonlinear decay of adventitial fluorescence indicated liquid flux from the injection site into normal interstitium. In some experiments, we determined that the adventitial fluorescence flowed longitudinally along the venule length and filled single lymphatics. The fluorescence decay at the injection site was best described by equations of convective but not diffusive transport. The decay time constant (time to 37% initial), which relates inversely to hydraulic conductivity, increased 10-fold above baseline on lung expansion with airway pressure from 5 to 15 cmH2O (P < 0.05). However, presence or absence of blood flow, increase in filtration pressure, and tissue edema were all without effect on the time constant. Our estimate of the lower limit of baseline adventitial hydraulic conductivity was 5 x 10(-6) ml.cm-2.s-1.cmH2O-1. We conclude that hydraulic conductivity of perimicrovascular adventitia is not augmented by edema but that it is decreased by lung expansion.

Albumins↗
PubMed1994

A simple medium without blood modified for successful isolation & cultivation of LD bodies.

A simple growth medium for primary isolation and subsequent cultivation of Leishmania donovani promastigotes without using whole blood is described. This medium is modified from Aljeboori's biphasic medium (used originally only for cultivation), containing only beef extract, peptone, sodium chloride, bactoagar and foetal calf serum (FCS). We have modified the medium by adding glucose and ascertaining the pH in the solid phase and by drastically reducing (91%) FCS in the liquid phase. The medium helps in isolation of L. donovani promastigotes from kala-azar patients, in addition to luxurious growth of parasites. The medium is simple, reliable, reproducible and convenient, with minimal interference in using the parasitic cells for immunological, molecular and isoenzyme studies.

Animals↗
PubMed1993

Calcium dependent thiol protease caldonopain and its specific endogenous inhibitor in Leishmania donovani.

A calcium dependent proteolytic enzyme was detected in the lysed promastigotes of Leishmania donovani, the causative agent of kala-azar. The protease was able to hydrolyse an added substrate, azocasein and showed high affinity for calcium. Rate of azocasein digestion was primarily slow but boosted up after eight hours. It was not inactivated when heated at 55 degrees C for 15 min at pH 7.4. Sulfhydryl reagents significantly reduced the enzymic activity but trypsin-like protease inhibitors hardly had any effect. The enzyme was not sensitive to calmodulin from a heterologous source but registered low activity when treated with chlorpromazine. The caseinolytic activity was stimulated when leishmanial cells were preincubated with ionophore A23187 in presence of 1 mM Ca2+. The enzyme is named caldonopain due to its similarity with a general class of calcium dependent protease calpain present in different tissues and cells. Caldonopain was found to be localized in cytosol along with its specific endogenous inhibitor caldonostatin. The ratio of caldonopain-caldonostatin unit was higher in the infected macrophage compared to the parasitic protozoa and Balb/c macrophage alone. It may be postulated that the amount of both calcium and its protein inhibitor may have a direct impact on the caldonopain-induced biological process to regulate cellular action of this pathogen.

Animals↗
PubMed1993

Effects of hyperoncotic albumin on endothelial barrier properties of rat lung.

We have determined the effect of concentrated albumin on lung endothelial hydraulic conductivity (Lp) by our split-drop technique. We anesthetized 39 rats (2% halothane and pentobarbital sodium, 30 mg/kg ip; Sprague-Dawley, 500 g), then isolated and blood perfused their lungs. At constant inflation pressure (5 cmH2O) and stopped blood flow, we viewed subpleural venules (diameter, 20 microns) by microscopy and video. By micropuncture, we first microinfused a venule for 6 min with albumin that was either isoncotic (4 g/dl) or hyperoncotic (6 g/dl) with respect to rat plasma. In the same venule we then injected and split an oil drop with 4 g/dl albumin. From the rates of movement of the split oil drop at different vascular pressures, we determined Lp for 4 g/dl albumin. In venules that were previously microinfused for 6 min with 4 g/dl albumin, Lp for 4 g/dl albumin did not differ from that of noninfused controls (5.4 +/- 0.8 x 10(-7) ml.cm-2.s-1.cmH2O-1). However, after a similar microinfusion of 6 g/dl albumin, the Lp immediately increased more than two times above baseline (P < 0.01) but returned to baseline after 15 min. Lp for 4 g/dl albumin was not affected by hyperoncotic preinfusions of either neutral dextran or immunoglobulin G. We conclude that concentrated albumin caused a reversible increase of the lung endothelial barrier conductivity.

Animals↗
PubMed1993

Hydraulic conductivity of ischemic pulmonary venules.

We report the first determination of lung endothelial barrier properties in ischemic, nonreperfused microvessels. We quantified the endothelial barrier in terms of hydraulic conductivity (Lp) in single pulmonary venules (diameter 20-50 microns) of isolated blood perfused lungs (dog, rat), held at constant inflation pressure (5 cmH2O) with a gas mixture containing 21% oxygen. Lp were determined by our split-drop technique in which an oil drop is first microinjected into a venule and then split by microinjection of a protein solution. Lp was interpreted from measurements of the rate of oil drop movement. Baseline Lp recorded in the first 30 min of perfusion averaged 3.4 +/- 0.9 x 10(-7) ml/(cm2.s.cmH2O). Then, in two separate groups of venules in which we established 1.3 +/- 0.1 h and 3.4 +/- 0.8 h of ischemia, we determined Lp which were, respectively, 145 +/- 6.5 and 308 +/- 13% above baseline (P < 0.05). We conclude that ischemia alone, in the absence of reperfusion, significantly deteriorates the lung endothelial barrier.

Animals↗
PubMed1993

Effect of vascular pressure on interstitial pressures in the isolated dog lung.

We report the first direct measurements of the effect of pulmonary vascular pressures on perialveolar interstitial pressures. In seven experiments we varied the intravascular pressure (Pvas) in isolated dog lungs held at constant airway pressure (PA). By the micropuncture servo-null technique, we recorded perialveolar interstitial pressures with respect to pleural pressure (0 cmH2O) at the alveolar junctions (Pjct) and in microvascular adventitia (Padv). At PA = 7 cmH2O, increase from 5 to 15 cmH2O did not affect Pjct, although it decreased Padv by 1.2 +/- 0.4 cmH2O. The Pjct-Padv gradient increased by 77%. Increasing Pvas to 25 cmH2O had no further effect on either interstitial pressure. In four experiments we also determined interstitial pressure in the hilum (Phil). When Pvas was increased from 5 to 15 cmH2O, Phil increased by 4.5 +/- 0.9 cmH2O. Further elevation of Pvas to 25 cmH2O increased Phil further by 2.4 +/- 0.4 cmH2O. At PA = 15 cmH2O, all interstitial pressures decreased, but their responses to Pvas were similar. We conclude that increase of Pvas 1) increases Phil but not perialveolar interstitial pressures and 2) increases the perialveolar interstitial pressure gradient, which may promote local liquid clearance.

Animals↗
PubMed1993

Hemodynamic effects of brief pulmonary hemostasis.

We determined the hemodynamic effects of brief hemostasis in isolated blood-perfused rat lungs held at constant inflation pressure. Three periods of hemostasis, each lasting 20 min, alternated with equal durations of perfusion. Pulmonary vascular resistance (PVR), calculated as the ratio of the pulmonary arterial- (Ppa) left atrial (Pla) pressure difference to flow, was determined at baseline and after the third hemostasis period. Hemostasis increased PVR by 127% above baseline at constant Ppa and Pla (n = 8; P < 0.05) and by 71% at constant Pla and constant flow (n = 16; P < 0.05). The PVR increases were significantly attenuated by platelet (n = 5) or red blood cell (n = 4) removal from the lung perfusion, mechanical ventilation (n = 5), indomethacin (2 X 10(-6) M; n = 5), papaverine (10(-5) M; n = 4), and the thromboxane blocker SQ-29548 (7.8 X 10(-5) M; n = 4). By micropuncture we determined that the posthemostasis increase of the total pressure drop was 66% due to an increase of the venous pressure drop (P < 0.05). Isogravimetric pressure and lung water were not significantly altered by hemostasis. We conclude that brief hemostasis in the rat lung induces platelet- and red blood cell-dependent increase of vascular resistance. This effect may be attributable to hemostasis-induced platelet activation leading to thromboxane release.

Animals↗
PubMed1993

Soluble complex of complement increases hydraulic conductivity in single microvessels of rat lung.

We determined the effect of sera enriched with the soluble complex of complement (SC5b-9), on hydraulic conductivity (Lp) of single pulmonary venules (diameter 20-30 microns). Sera free of anticoagulants and blood cells were prepared from rat and human blood. Lp were determined by our split drop technique in isolated, blood-perfused lungs prepared from anesthetized rats (2% halothane; Sprague Dawley, 500 g; n = 73). Zymosan-activated (ZAS) and control sera were used for Lp determinations. In ZAS prepared from human serum, SC5b-9 concentration was > 300 micrograms/ml (control: < 1 microgram/ml) as determined by ELISA. At baseline, Lp averaged 3.4 +/- .4 x 10(-7) ml/(cm2.s.cm H2O), but it increased by 217 +/- 32% with undiluted ZAS (P < 0.05). The Lp increase correlated significantly with different ZAS dilutions for rat serum and with SC5b-9 concentration for human serum. Lp did not increase significantly with ZAS prepared from heat-treated sera, C6- and C8-deficient sera; or with ZAS in which SC5b-9 had been depleted by immunoprecipitation. The ZAS-induced increase of Lp was blocked completely by venular preinfusion with the arginine-glycine-aspartic acid (RGD) tripeptide (1 mg/ml, 10 min). We report for the first time that: (a) SC5b-9 increases lung endothelial Lp; and (b) the increase of Lp is attributable to an integrin-dependent mechanism.

Animals↗
PubMed1992

Screening of hearing impairment in the newborn using the auditory response cradle.

The Auditory Response Cradle (ARC) is a fully automated microprocessor controlled machine that was designed for the hearing screening of full term neonates. In order to evaluate the ARC, 6000 babies were screened at a district maternity hospital over a period of three years. Every infant subsequently entered a three year follow up programme. One hundred and two babies (1.7%) failed the ARC screen (that is, they failed two ARC tests) and 20 of these were found to have some hearing impairment: in 10 it was severe (80-90 dBHL), in seven moderate (45-60 dBHL), and in three it was mild to moderate (less than 45 dBHL). In addition, of the 20 babies who failed a first test and were discharged before a second could be performed, two were confirmed to have a severe hearing loss; 79 infants failing the screen were cleared on further testing, giving the ARC a false positive rate of 1.3%. On following up all 6000 infants for three years, seven children who passed the neonatal screen were subsequently found to have a hearing loss. For two babies the aetiology was unknown but for five the hearing impairment was either due to a hereditary progressive loss or definite postnatal factors. Progressive and acquired hearing losses cannot be detected at a neonatal screen and this emphasises the need for follow up screens at other stages in the child's life. In this long term study the ARC has been found to have a high detection rate for severe hearing loss and confirms the practical possibility of using a behavioural technique for the universal screening of hearing in neonates.

England↗
PubMed1992

Segmental vascular responses to voltage-gated calcium channel potentiation in rat lung.

We determined lung vascular responses to voltage-gated Ca2+ channel potentiation with BAY K 8644 (BAY). We anesthetized 46 rats (Sprague-Dawley; halothane and pentobarbital) and then excised and perfused their lungs at constant blood flow of 25 +/- 2 (SE) ml.kg-1.min-1 at constant airway and left atrial pressures of 5 and 6 cmH2O, respectively. Pulmonary arterial pressure (Ppa) increased from 13.3 +/- 0.3 cmH2O at baseline to 17.3 +/- 1.3 cmH2O after BAY (2.8 x 10(-6) M; n = 5; P less than 0.01). As determined by micropuncture, arteriolar and venular (Pven) pressures did not change. Increase of perfusate Ca2+ (16 x 10(-3) M; n = 8) similarly increased Ppa. NG-mono-methyl-L-arginine (2 x 10(-4) M), an inhibitor of endothelium-derived relaxing factor, augmented the pressor effect of BAY when given after (n = 4) but not before (n = 4) BAY (P less than 0.01). Prior cyclooxygenase blockade with indomethacin (5 mg/kg; n = 5) attenuated the Ppa response to BAY (P less than 0.01). None of these agents changed Pven. To confirm vasoactivity in veins, we induced smooth muscle depolarization with KCl (20 x 10(-3) M; n = 6) and receptor-mediated responses with histamine (3 x 10(-4) M; n = 7). Both of these agents increased Pven markedly (P less than 0.01). We interpret that, in rat lung, BAY causes arterial but not venous constriction, because the venous segment differs from the arterial with regard to Ca2+ channel potentiation.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1991

Effect of alveolar and pleural pressures on interstitial pressures in isolated dog lungs.

We report the first direct measurements of perialveolar interstitial pressures in lungs inflated with negative pleural pressure. In eight experiments, we varied surrounding (pleural) pressure in a dog lung lobe to maintain constant inflation with either positive alveolar and ambient atmospheric pleural pressures (positive inflation) or ambient atmospheric alveolar and negative pleural pressures (negative inflation). Throughout, vascular pressure was approximately 4 cmH2O above pleural pressure. By the micropuncture servo-null technique we recorded interstitial pressures at alveolar junctions (Pjct) and in the perimicrovascular adventitia (Padv). At transpulmonary pressure of 7 cmH2O (n = 4), the difference of Pjct and Pady from pleural pressure of 0.9 +/- 0.4 and -1.1 +/- 0.2 cmH2O, respectively, during positive inflation did not significantly change (P less than 0.05) after negative inflation. After increase of transpulmonary pressure from 7 to 15 cmH2O (n = 4), the decrease of Pjct by 3.3 +/- 0.3 cmH2O and Pady by 2.0 +/- 0.4 cmH2O during positive inflation did not change during negative inflation. The Pjct-Pady gradient was not affected by the mode of inflation. Our measurements indicate that, in lung, when all pressures are referred to pleural or alveolar pressure, the mode of inflation does not affect perialveolar interstitial pressures.

Animals↗
PubMed1991

Segmental barrier properties of the pulmonary microvascular bed.

We determined liquid flux across single pulmonary microvessels of dog, ferret, and rat by our split-drop technique (J. Appl. Physiol. 64: 2562-2567, 1988). Data are reported from 58 lungs excised under halothane or pentobarbital sodium anesthesia and then blood perfused. We stopped blood flow at known vascular pressures and then micropunctured microvessels to inject oil, which we split with albumin solution. From measurements of vessel diameter and split oil drop length, we calculated Jv, the liquid transport rate per unit surface area [x 10(-6) ml/(cm2.s)]. At constant vascular pressure, Jv was not significantly different after different periods of oil-endothelium contact and at different sites within a single vessel. From measurements of Jv at different vascular pressures, we determined Lp, the hydraulic conductivity [x 10(-7) ml/(cm2.s.cmH2O)], and Pzf, the zero filtration pressure. From determinations of Pzf at different albumin concentrations, we quantified sigma alb, the albumin reflection coefficient. Lp and Pzf did not differ among venules of the same lung. However, in venules, Lp was 40% higher and sigma alb 25% lower than in arterioles (P less than 0.01). We conclude that 1) micropuncture procedures incidental to our split-drop technique do not progressively deteriorate the experimental microvessel and 2) in lung, permeability is higher in venules than in arterioles.

Animals↗
PubMed1991

A simple method for cryopreservation of Leishmania donovani promastigotes.

Cryopreservation of promastigotes of L. donovani in NNN and Tobie's media was attempted. The media containing the promastigotes were kept directly at -80 degrees C. The cryopreserved media were examined for living promastigotes after 9, 12, 15, 20, 23, 26, 29, 32, 42, 56, 65 and 126 days after the culture tubes were brought directly from -80 degrees C to room temperature and examined after 30 min. All tubes showed living promastigotes which were used for further growth with no apparent morphological changes in subsequent subcultures. Viability was optimum. This method of short term cryopreservation is simple, reliable and reproducible for cryopreservation of culture adapted parasites and also important because different strains can be stocked without using any other chemical, or special equipment and liquid nitrogen chamber, for further use in immunological or other purposes.

Animals↗
PubMed1989

Hydraulic conductivity of endothelial cell monolayers cultured on human amnion.

Hydraulic conductivity (Lp) of endothelial cell monolayers cultured on a supporting matrix of human amnion was measured. Bovine aortic (Baec), bovine microvascular (Bmec), and human umbilical vein endothelial cell (Huvec) monolayers were mounted in a water-jacketed chamber maintained at 37 degrees C. The lower compartment of the chamber was connected to an electronic sensor-aspiration system that served to volume clamp the lower compartment. The aspirated volume was displayed on a chart recorder, providing continuous measurements of volume flow per unit area (Jv). In 36 monolayers, Jv was linearly related to hydrostatic pressure. The average slope of this relationship (Lp) was 1.14 +/- 0.8 X 10(-6), 1.67 +/- 1.49 X 10(-6), and 2.9 +/- 0.85 X 10(-6) cm.s-1.cmH2O-1 for Baec, Bmec, and Huvec, respectively. The effect of increased luminal oncotic pressure was studied in seven monolayers. The oncotic pressure difference (delta pi) ranged from 3.1 to 7.1 cmH2O (measured with a Wescor oncometer). In all cases, there was an immediate fall in Jv and a displacement to the right of the x-intercept of the line Jv vs. change in pressure (delta P) without a change in the slope (Lp). These results indicate that the Lp of endothelial cell monolayers cultured on amnion is within the range of values previously reported for single capillaries in vivo and that these monolayers appear to sustain delta pi sufficient to generate an osmotically driven water flow.

Amnion↗
PubMed1989

Hyaluronan affects extravascular water in lungs of unanesthetized rabbits.

We have determined whether changes in lung hyaluronan content affect extravascular water in lungs of unanesthetized rabbits. Three groups of experiments were performed. In group 1 (n = 12), no infusions were given; in group 2, nine pairs of rabbits received either intravenous hyaluronidase (750 U.kg-1.min-1) or an equivalent volume of saline; in group 3, nine pairs of rabbits received either hyaluronidase or saline, followed by intravenous saline infusion amounting to 24% of body weight. At the end of each experiment, one lung was analyzed for extravascular lung water by the wet-dry method. Except for group 3, in all animals the other lung was analyzed for hyaluronan content by a method that involved hydrolyzing lung hyaluronan with fungal hyaluronidase to release reducing N-acetyl glucosamine groups, which were quantified. In group 1, lung hyaluronan, which varied from 50 to 159 micrograms/g dry wt (mean 106 +/- 35 micrograms/g dry wt), significantly correlated with variation in extravascular lung water (mean 4.2 +/- 0.3 g/g dry wt). In group 2 rabbits given hyaluronidase, lung hyaluronan was 40% lower and extravascular lung water was 14.6% lower than in paired controls (P less than 0.01). In group 3, volume expansion did not affect lung water, except after hyaluronidase when lung water was 47% higher than paired controls. We conclude that in the lung the content of hyaluronan is one of the determinants of extravascular water content.

Animals↗
PubMed1989

Lung expansion and the perialveolar interstitial pressure gradient.

We have determined the combined effects of lung expansion and increased extravascular lung water (EVLW) on the perialveolar interstitial pressure gradient. In the isolated perfused lobe of dog lung, we measured interstitial pressures by micropuncture at alveolar junctions (Pjct) and in adventitia of 30- to 50-microns microvessels (Padv) with stopped blood flow at vascular pressure of 3-5 cmH2O. We induced edema by raising vascular pressures. In nonedematous lobes (n = 6, EVLW = 3.1 +/- 0.3 g/g dry wt) at alveolar pressure of 7 cmH2O, Pjct averaged 0.5 +/- 0.8 (SD) cmH2O and the Pjct-Padv gradient averaged 0.9 +/- 0.5 cmH2O. After increase of alveolar pressure to 23 cmH2O the gradient was abolished in nonedematous lobes, did not change in moderately edematous lobes (n = 9, EVLW = 4.9 +/- 0.6 g/g dry wt), and increased in severely edematous lobes (n = 6, EVLW = 7.6 +/- 1.4 g/g dry wt). Perialveolar interstitial compliance decreased with increase of alveolar pressure. We conclude that increase of lung volume may reduce perialveolar interstitial liquid clearance by abolishing the Pjct-Padv gradient in nonedematous lungs and by compressing interstitial liquid channels in edematous lungs.

Animals↗