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Biomedical subjects

L Gotloib

Publications and source records attributed to L Gotloib.

At least 37 records · Page 2Linked to original sources
PubMed1996

Increased peritoneal permeability to albumin in streptozotocin diabetic rats.

The mechanism behind the increased peritoneal permeability to albumin in diabetics is still unclear. In this study, streptozotocin diabetic rats developed albuminuria and significantly increased D/P of albumin after the fourth week of disease, reaching peak levels at the end of the 24 week period of follow-up. Coincidentally, extravasation of albumin to the interstitial tissue was evaluated with the Evans-blue method. Age-matched control rats showed Evans-blue concentrations of 0.023 +/- 0.013 micrograms/100 mg of dry tissue, whereas in diabetics the numbers were 1.22 +/- 0.719 micrograms (P < 0.001). Perfusion with Ruthenium-Red (RR) done in control at zero time, and in age-matched intact as well as in diabetic rats after 24 weeks of disease showed that the density distribution of capillary subendothelial anionic sites was significantly lower for diabetics (13 +/- 3/microns basement membrane vs. 31 +/- 3 and 34 +/- 4 in control groups; P < 0.001). Similar findings were made on the mesenteric submesothelial basement membrane. Mean density of RR decorated anionic sites was 12 +/- 2/microns basement membrane in diabetics, whereas those observed in both control groups were 31 +/- 2 and 31 +/- 3/microns (P < 0.001). Therefore, this reduced density of microvascular and submesothelial negative charges, equivalent to that induced by diabetes in other capillary beds, appears to be at the origin of the decreased permselectivity of the diabetic peritoneum for anionic serum albumin.

Albumins↗
PubMed1996

Daily short exposure of cultured mesothelial cells to lactated, high-glucose, low-pH peritoneal dialysis fluid induces a low-profile regenerative steady state.

This study was designed to evaluate cytotoxic effects and influence upon cell growth of cultured mesothelial cells exposed to modified 4.25% Dianeal dialysate fluid (M-199 in Dianeal solution, glucose 4.25 g, pH 5.2) (Expr. group), 60 min a day for a total period of follow-up of 13 consecutive days, compared with that observed in a control group (C). Beginning on day 7, the cell counts in group C were significantly higher than those observed at zero time (P < 0.05). Cell counts in the experimental group showed no significant differences between the first day of culture and each one of the 13 consecutive days of follow-up. Thymidine incorporation into DNA observed on the first day in C, was significantly higher (P < 0.01) beginning on the 10th day. Values observed in the experimental group were low during the whole period of follow-up. LDH mean values at each time interval, were significantly higher (P < 0.01 and < 0.001) for cells exposed to the dialysis solution. Repeated exposure of the mesothelium to 40 mMol/l lactate and high glucose concentrations induced severe cell injury and death, decreased cell growth and, consequently, a reduced rate of regeneration which is extended as long as the repeated exposure is maintained.

Animals↗
PubMed1996

Population analysis of mesothelium in situ and in vivo exposed to bicarbonate-buffered peritoneal dialysis fluid.

Population analysis of mesothelium (PAM) done using the in vivo and almost in situ technique of mesothelial cell imprints revealed that lactate-buffered solutions had detrimental effects upon cell viability, that high glucose concentration affected cytokinesis, whereas the association of both components led to a decreased density population of cells showing a larger surface area. In the present study, PAM was done on mesothelium of mice exposed to bicarbonate-buffered peritoneal dialysis fluid (BBF) with glucose concentrations of 1.5 and 4.25%, for periods of time of 2 h, 15 and 30 days, as well as after recovery intervals of 7 and 30 days, BBF did not affect mesothelial cell viability. However, the increased incidence of multinucleated cells observed with both glucose concentrations, more marked with the 4.25% solution, suggests a detrimental effect upon the mechanism of cytokinesis. Furthermore, the higher the glucose concentration, the higher the mean-cell cytoplasmic surface area and the proportion of large cells, both resulting most probably from the regulatory volume increase developed by cells continuously exposed to hyperosmolar fluids. So far, evidence presented in this study suggests once more that BBF is remarkably more compatible with a higher quality of adaptation and survival of the exposed mesothelium than the lactated fluid. The question of whether the alterations induced by the high concentration of glucose result from a specific effect of glucose, by the coincidental hyperosmolarity, or by both still remains unanswered.

Animals↗
PubMed1996

Cultured rat mesothelial cells generate hydrogen peroxide: a new player in peritoneal defense?

This study was designed to examine whether rat peritoneal mesothelial cells in culture could generate hydrogen peroxide in different experimental conditions. Mesothelial cells, incubated in M-199, spontaneously released hydrogen peroxide. This process was significantly increased by addition of phorbol myristate acetate, as well as of superoxide dismutase to the medium, whereas it was substantially inhibited by catalase. Exposure of mesothelial cells to modified M-199 medium with 1.5% glucose concentration-lactated peritoneal dialysis solution did not seem to interfere either with the spontaneous release of hydrogen peroxide, or with that induced by phorbol myristate acetate. Furthermore, exposure of mesothelial cells to the glucose (4.25%) peritoneal dialysis solution in Medium M-199, was coincident with increased hydrogen peroxide generation, which was significantly higher than the spontaneous release, and not far from that observed with phorbol myristate acetate and superoxide dismutase. So far, it can be inferred from this evidence that peritoneal mesothelial cells in culture are not only endowed with the capability of producing hydrogen peroxide, but they can also be activated to do so in a way comparable to that observed in neutrophils and macrophages. This attribute is one more indication that mesothelial cells play a relevant role in the peritoneal mechanism of defense against infection. On the other hand, continuous exposure of mesothelial cells to glucose-enriched fluids, as occurs in clinical continuous ambulatory peritoneal dialysis, may well also be at the origin of a process of continuous injury, resulting from an increased hydrogen peroxide generation.

Animals↗
PubMed1995

Treatment of surgical and non-surgical septic multiorgan failure with bicarbonate hemodialysis and sequential hemofiltration.

OBJECTIVE: Hospital mortality of patients with septic multiorgan failure (MOF) is still around 95%. The present study investigates whether this high mortality could be significantly reduced by the addition of sequential hemofiltration (SH) with bicarbonate hemodialysis (HD) to the currently used life supportive measures. DESIGN: 35 (18 surgical and 17 nonsurgical) patients, with 3 or more organ failures, had daily sessions of zero balance SH, for periods ranging from 2-22 days. MEASUREMENTS AND RESULTS: SH induced significant improvement of PaO2/100 FIO2, Apache II score, MAP, as well as blood chemistry in survivors. Dying patients had less marked improvement of blood oxygenation, non-significant changes in other variables, in addition to low MAP before and after SH, as well as marked hemodynamic unstability during the procedure. The observed hospital mortality was 38% for the surgical group, and 35.3% for the medical patients (n.s.). CONCLUSIONS: Mortality observed in this retrospective, uncontrolled study was significantly lower than that currently observed with conventional supportive therapy, with or without the addition of other forms of blood purification, e.g. CAVH and CAVHD. This improvement in results appears to be related to the property of SH to completely clear 90% of the blood from mediators of inflammation in only one passage through the hemofilter, and to better tolerance of HD done using bicarbonate buffer. A definite evaluation of this technique will be eventually reached by a programmed, appropriate sample size study, which is out of reach for one individual ICU.

Adult↗
PubMed1995

Endocytosis and transcytosis of albumin gold through mice peritoneal mesothelium.

The present transmission electron microscopy (TEM) study was designed to investigate whether mesothelial cells of mice diaphragmatic, parietal and mesenteric peritoneum are actively coupled to the mechanisms involved in the transerosal absorption of albumin gold complexes (Alb-Au). Five albino mice were injected intraperitoneally with 0.5 ml of a suspension of Alb-Au. In three animals, in vivo fixation was done 10 minutes after injection of Alb-Au, whereas in the remaining two, fixation was performed 45 minutes after injection of the tracer. At both time intervals, a substantial part of Alb-Au complexes was observed within plasmalemmal and coated vesicles, mainly attached to the luminal aspect of the internal luminal membranes. The amount of Alb-Au contained in plasmalemmal vesicles was significantly higher than that detected in intermesothelial junctions. Plasmalemmal vesicles were observed discharging Alb-Au complexes in the submesothelial interstitium, showing a significantly higher proportion of the tracer associated with non-junctional areas. Evidence presented in this study supports the idea of local degradation of Alb-Au in mesothelial cells after endocytosis, and that of a continuously transcytotic mechanism transporting polymerized albumin across the mesothelial layer. In this sense, transcytotic vesicles could represent the large pore equivalent.

Animals↗
PubMed1995

The cytochemical profile of visceral mesothelium under the influence of lactated-hyperosmolar peritoneal dialysis solutions.

Male albino mice had one daily intraperitoneal injection of 4.25 g/100 ml glucose concentration fluid for peritoneal dialysis at pH 5.0-5.2, for a period of 30 days. At the end of the experimental periods, mesothelial cell imprints were taken from the peritoneal layer of the anterior liver surface. Histochemical staining of imprints obtained from mice exposed to the peritoneal dialysis fluid showed a consistently increased activity of: (a) enzymes associated with the cell membrane: Na-K-ATP-ase, alkaline phosphatase and 5-nucleotidase; (b) cytoplasmic enzymes: acid phosphatase and cytochrome oxidase, and (c) a modestly increased activity of glucose-6-phosphatase. These changes, which are not far from those observed in activated mesothelial cells, suggest that exposure of mesothelial cells to high glucose concentrations of PD fluid is associated with increased production and disposal of energy to be used for maintaining the constancy of the cellular environment and, probably, for fuelling the transcellular transport of solutes of large molecular size.

5'-Nucleotidase↗
PubMed1995

Acute and long-term changes observed in imprints of mouse mesothelium exposed to glucose-enriched, lactated, buffered dialysis solutions.

Solutions for peritoneal dialysis (PD), the hyperosmolarity of which is obtained with glucose, have been shown to initiate and maintain a situation of continuous mesothelial cell injury associated with a process of regeneration which also takes place continuously. The present study was done using the in vivo and almost in situ technique of mesothelial cell imprints. Acute exposure to 4.25% glucose solution at pH 5.2 and 7.0 induced higher mitotic activity, defective cytokinesis, and reduced cell viability. Long-term exposure (15 and 30 days) to both 4.25% glucose solutions was associated with a reduced population density, increased surface area, and lower mesothelial cell viability, regardless of the pH. The use of 1.5% glucose fluid showed that this effect was dose related. After 30 days of recovery, mesothelial cells exposed to the high-glucose solution at both pH 5.2 and 7.0 appeared repopulated by small cells and showed evidence of defective cytokinesis. So far, it appears that the alterations observed after long-term exposure of the mesothelium to PD fluid are mainly caused by the high concentration of glucose per se. The additional effects of hyperosmolarity are still unclear, whereas the eventual role of low pH, at least in the experimental model used here, can be defined as less than marginal.

Analysis of Variance↗
PubMed1992

Loss of microvascular negative charges accompanied by interstitial edema in septic rats' heart.

We studied the effect of Gram-negative sepsis on negative charges of heart capillaries and myocardial cells. We used a rat model of multiorgan failure, with ruthenium red (RR) and polyethyleneimine (PEI) as cationic binding tracers. Twenty-four hours after induction of sepsis, negative charges had decreased in glycocalyx and basement membrane of myocardial capillary endothelial cells. There were substantial amounts of interstitial edema. Density of anionic charges in the sarcolemmal glycocalyx complex of cardiac cells was markedly reduced. Myocardial cells' mitochondria consistently showed morphologic changes, whose severity ranged between stages II and IV C of Trump. Thirteen days after induction of sepsis, capillary endothelial and myocardial cells had recovered almost completely and showed no intracellular edema. Gram-negative sepsis caused a significant reduction in negative charges normally present in the microvascular wall as well as on myocardial cells. Consequently, several membranes limiting the various compartments of heart tissue lost their structural integrity. This morphometric data could explain the development of protein-rich interstitial edema and defective cell volume regulation observed in cardiac muscle of endotoxin-shocked animals. This myocardial edema may be at the origin of the cardiac dysfunction observed in both experimental and human septic shock.

Animals↗
PubMed1991

Protamine sulfate induces enhanced peritoneal permeability to proteins.

We present a direct link between the neutralization of anionic sites by intraperitoneal protamine and a rise in protein passage to the peritoneal cavity during isosmotic peritoneal dialysis in rabbits. Each experiment included two 1-hour exchanges. No drugs were added in the first exchange. In group A (control) there were no drugs in the second hour either. In group B, protamine (50 micrograms/ml) was added to the second exchange volume. In group C, protamine and heparin (50 U/ml) were added. In groups A and C, appearance curves of metabolites during the first (baseline) and the second (experimental) hours were not statistically different. In group B, differences for urea, glucose and uric acid were not significant, but they were highly so for protein (increase of 100%, p less than 0.01). Transperitoneal passage of albumin is substantially enhanced by protamine. Neutralization of protamine with heparin prevents this, showing that availability of anionic sites is the crucial limiting factor. Protamine did not significantly affect the transfer of small neutral molecules.

Animals↗
PubMed1990

Anionic fixed charges in the fenestrated capillaries of the mouse mesentery.

Previous studies showed the existence of submesothelial fenestrated capillaries in the human parietal and rabbit diaphragmatic peritoneum, as well as in the mouse mesentery. The present study demonstrates the presence of electronegative fixed charges at the luminal aspect of endothelial cells, as well as long the subendothelial basement membrane of the fenestrated capillaries of the mouse mesentery. This situation will eventually preclude the transfenestral passage of anionic plasma proteins. On the other hand, fenestrated capillaries are much more permeable to water and small-molecular-size solutes than those of the continuous type. Therefore, the high hydraulic conductivity of fenestrae may well imply that a substantial part of water and small solutes leave the blood compartment through the fenestral channels.

Animals↗