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Biomedical subjects

A Pomeranz

Publications and source records attributed to A Pomeranz.

At least 55 records · Page 3Linked to original sources
PubMed1990

Atrial natriuretic peptide-induced increase of glomerular filtration rate, but not of natriuresis, is mediated by prostaglandins in the rat.

This study addressed the question of whether some renal effects of atrial natriuretic peptide (ANP) are mediated by prostaglandins (PGs). Inhibition of PG synthesis (aspirin, 10 mg/kg) abolished the increase in inulin clearance (CIN) induced by ANP in rats. In contrast, diuresis and natriuresis remained significantly elevated after aspirin administration. ANP, either infused in vivo immediately before sacrifice or added to the incubation tubes, stimulated the synthesis of PGE2 and 6-keto-PGE1 alpha by isolated rat glomeruli but not by medullary or papillary slices. We conclude that the effect of ANP on the glomerular filtration rate is PG dependent, whereas that on diuresis and natriuresis is direct.

Animals↗
PubMed1990

Cat-scratch bacillus and Streptococcus pneumoniae causing submandibular suppurative adenitis and acute glomerulonephritis.

Acute cervical adenitis is a frequent problem in pediatrics. It is occasionally followed by acute postinfectious glomerulonephritis, which has a well-defined set of clinical and histological manifestations. We present two rare cases of acute postinfectious glomerulonephritis, one associated with Streptococcus pneumoniae and the second with cat-scratch disease. Cultures of material from the lymph nodes yielded S. pneumoniae type 15 in case 1. A pleomorphic gram-negative micro-organism, identified by silver stain as cat-scratch bacillus, was found in case 2.

Cat-Scratch Disease↗
PubMed1989

Endogenous digoxin-like factor raises blood pressure and protects against digitalis toxicity.

Digoxin-like immunoreactive factor (DLIF) is an endogenous natriuretic material which causes diuresis and natriuresis after salt or fluid loading and which may play a pathogenetic role in various hypertensive states. In order to study the cardiovascular effects of DLIF, we administered partially purified material (500 ng/kg) iv to normal rats. DLIF administration caused a significant rise in blood pressure, induced a brisk diuresis, and slowed the heart rate. In addition, DLIF protected against digitalis toxicity. While iv digoxin, 1 mg/kg, uniformly produced lethal arrhythmias, administration of DLIF 15 min prior to digoxin infusion consistently protected against arrhythmias. These findings support the theory that DLIF may play a role in hypertension. In addition, DLIF may compete with digoxin for cardiac receptors.

Animals↗
PubMed1989

Presence of an anti-viral factor in peritoneal dialysis effluent.

Viral peritonitis is an exceptionally rare occurrence in peritoneal dialysis. In fact, up to now, only one case report has been documented in the literature. In a prospective study, peritoneal dialysis effluent (PDE) was specifically cultured for the following viruses: the herpes group of viruses, including herpes simplex types I (HSV) and II, cytomegalovirus (CMV) and varicella-zoster (V-Z), and the enteroviruses group including coxsackie B-5 (Cox B), echo, enterovirus and polio. Cultures were performed under both basal conditions and in the presence of peritonitis. No viral growth was demonstrated. The possible existence of an anti-viral factor in the PDE was therefore raised. In order to investigate this hypothesis, the PDE of 16 patients undergoing intermittent peritoneal dialysis and of 24 patients on continuous ambulatory peritoneal dialysis were examined for anti-viral activity. The method used was analogous to that employed for testing the anti-viral effect of interferon (IFN). The inhibition of the cytopathic effect (CPE) of various viruses was examined in the following tissue cultures: Vero cells (a line of monkey kidney cells) incubated with HSV, vesicular stomatitis virus (VSV) and Cox B; human kidney cells incubated with parainfluenza 3 (Para-3); human foreskin fibroblasts incubated with CMV, HSV and VSV and L-929 (a line of mouse cells) incubated with VSV. As control, unused Dianeal (Travenol, Ashdod, Israel) 1.5 and 4.25 g/dl, normal saline and 5 g/dl dextrose solutions were tested under the same conditions using VSV on Vero. The PDE was also examined for the presence of specific anti-viral antibodies by microneutralization and ELISA tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Effects of sodium depletion on renal prostanoid synthesis in rats: influence of the converting enzyme inhibitor captopril.

1. The synthesis of prostaglandin (PG) E2, PGF2 alpha, 6-keto-PGF1 alpha and thromboxane (TX) B2 by isolated glomeruli, cortical tubules, inner medullary slices and outer medullary slices was measured in salt-depleted (LNa) rats and in salt-depleted rats receiving captopril (LNa-CEI). Animals were studied before and after 4, 9 and 15 days of Na+ depletion. 2. Na+ balance was reached in LNa rats after 4 days. Blood pressure and creatinine clearance remained stable. Serum Na+ decreased from 140 +/- 1 to 126 +/- 1 mmol/l (mean +/- SEM, P less than 0.01). In contrast, LNa-CEI rats were unable to conserve Na+ adequately: fractional excretion of Na+ and natriuresis were constantly greater than in LNa animals. As a consequence, LNa-CEI rats developed severe hyponatraemia, lost weight and their creatinine clearance decreased. 3. The glomerular synthesis of PGE2, PGF2 alpha and 6-keto-PGF1 alpha, but not of TXB2, was significantly increased in LNa rats. In LNa-CEI rats, the synthesis of PGE2 and 6-keto-PGF1 alpha was similar to control values, but PGF2 alpha and TXB2 synthesis was elevated at day 9. In cortical tubules, PGE2 and PGF2 alpha were unaffected by Na+ depletion, but 6-keto-PGF1 alpha and TXB2 were increased and a similar trend was observed in LNa-CEI rats. In outer medulla of LNa rats, a decrease in all the eicosanoids measured was observed at day 4. In LNa-CEI animals, the synthesis of PGE2 and PGF2 alpha, but not of 6-keto-PGF1 alpha and TXB2, was significantly depressed. In inner medulla, Na+ depletion only tended to decrease PGF2 alpha and 6-keto-PGF1 alpha, but in the presence of captopril, the synthesis of all prostanoids was significantly decreased.

6-Ketoprostaglandin F1 alpha↗
PubMed1989

Thrombin inhibits the synthesis of prostanoids by isolated glomeruli and peritoneal macrophages in rats.

Activation of macrophages and release of mediators that activate the coagulation system characterize proliferative glomerulonephritis. To evaluate the possible role of prostanoids in this process, isolated rat glomeruli (G) and peritoneal macrophages (M) or a combination of the two (G + M) were incubated in the presence of thrombin (2 U/ml). In G, thrombin inhibited only the synthesis of thromboxane B2. In M and G + M incubations, the synthesis of prostaglandin I2 and thromboxane A2 was inhibited by thrombin. This effect was abolished by the addition of arachidonic acid. As prostanoids may play a modulatory role in the interaction between macrophages and glomerular cells, inhibition of their synthesis by thrombin might enhance macrophage activity.

6-Ketoprostaglandin F1 alpha↗
PubMed1989

Quantitative method of measuring anti-viral activity of peritoneal dialysis effluent.

We have previously documented the presence of anti-viral activity in the peritoneal effluent of uremic patients treated by peritoneal dialysis. Anti-viral activity was determined by recording the inhibition of the cytopathic effect (CPE) of various viruses on Vero cells in a semi-quantitative manner based on observer's subjective judgment of the degree of inhibition of CPE. This degree of inhibition is a measure of the anti-viral activity. Although peritoneal dialysis effluent (PDE) was consistently seen to inhibit CPE we sought a quantitative method to accurately assess such anti-viral activity. To this end, the CPE of Parainfluenza virus (Para-3) on human kidney (Hu-K) cells was evaluated. The CPE of this virus is manifested by distinct plaques which can be easily counted after staining the tissue culture plate. Eighty-three (83) samples of PDE (0.5 ml) were added to Hu-K cells after which Para-3 was added. As control para-3 on Hu-K was used. The number of plaques obtained by virus control was taken as 100% CPE. The anti-viral activity of PDE was then recorded as the percentage of the CPE shown by virus control and averaged 20.9 +/- 28.6% (p less than 0.001 vs virus control). In addition PDE was diluted down to 1/64 concentration and the inhibitory effect again determined. Percent CPE of undiluted, 1/2, 1/64 PDE samples were 18.11 +/- 24.2, 33.57 +/- 18.16 and 77.93 +/- 17.4% respectively (p less than 0.01 between undiluted and 1/64 PDE). These data reaffirm that PDE possesses an inherent anti-viral activity which can now be quantitatively assessed using Para-3 on Hu-K cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Role of glomerular prostanoid in control of glomerular filtration rate in rats.

It is generally accepted that the main action of glomerular prostanoids (GPs) on glomerular filtration rate (GFR) is to modulate the activity of different vasoconstrictors, specially in states of renal hypoperfusion. However it was also suggested that GPs may directly affect GFR. The present study was focused on this last hypothesis, in different experimental models, in rats. In adriamycin induced acute renal failure, the transient decrease of GFR is associated with higher levels of thromboxane B2. Later on, when GFR returns to normal, vasodilator prostaglandins synthesis was also increased. In captopril induced renal failure in Na depleted rats (where GPs synthesis remained normal), stimulation of PGE2 and PGI2 production by K and NaCl was associated with a significant improvement of GFR. Furthermore, the increase in GFR induced by NaCl was prevented by inhibition of prostaglandin synthesis. Infusion of atrial natriuretic peptide in euvolemic rats induce a marked elevation both of GFR and PGE2 synthesis. It was abolished by previous administration of prostaglandin synthesis inhibitor. In conclusion, glomerular prostanoids may influence GFR, either directly, or as mediator or modulator of other vasoactive hormones.

Acute Kidney Injury↗
PubMed1988

Atrial natriuretic peptide administration to normal and salt depleted rats--effects on digoxin-like immunoreactive factor, aldosterone, ACTH, and renal function.

In view of the known interrelationships between renin, aldosterone, and atrial natriuretic peptide (ANP), we sought to examine whether there also exists an interaction between ANP and digoxin-like immunoreactive factor (DLIF). We therefore studied the effects of ANP administration on normal and salt-depleted rats, and measured the effects on blood pressure, urine output, glomerular filtration rate, sodium excretion, aldosterone, ACTH, and DLIF levels. ANP administration resulted in a significant elevation of sodium excretion and glomerular filtration rate and a fall in blood pressure. DLIF concentrations in plasma rose significantly, as did urinary DLIF excretion. ANP administration resulted in a fall in aldosterone as well as ACTH. These observations suggest that ANP has a direct inhibitory effect on ACTH secretion. Our findings support the concept of an interrelationship between ANP and DLIF.

Adrenocorticotropic Hormone↗
PubMed1988

Transcutaneous monitoring of blood gas tensions in patients on intermittent peritoneal dialysis.

A relative contraindication to intermittent peritoneal dialysis (IPD) is chronic lung disease. To evaluate whether the instillation of 2 L of fluid into the peritoneal cavity affects respiratory function, five IPD patients were studied in the supine position during the first 4 h of a routine IPD session. Blood gas tensions were monitored transcutaneously throughout the study period. At the onset of dialysis, mean transcutaneous blood oxygen tension (PtcO2) was 70.6 +/- 9.1 mm Hg. It decreased to 55 +/- 9.9 mm Hg (22% change from basal values) during the instillation of dialysate. Upon drainage, PtcO2 returned to baseline. This sequence of events repeated itself on subsequent exchanges, although with decreasing decrements of PtcO2 with each consecutive exchange (decrease to 58.6 +/- 7.05, 61 +/- 6.5, 63.8 +/- 5.2 mm Hg corresponding to 16%, 12.7%, and 9.6%, respectively, during the second to fourth exchanges). Transcutaneous blood carbon dioxide tension, PtcCO2, showed a very mild increase during the study (33 +/- 7.1 to 38 +/- 6.0 mm Hg). In two patients, the same study protocol was performed during the last 4 h of an IPD session. In these two patients, there was only a 5% variation of PtcO2 from baseline values. These results suggest that an adaptive response to the hypoxemia induced by dialysate instillation rapidly occurs in IPD patients.

Adult↗
PubMed1988

Prostanoids in renal failure induced by converting enzyme inhibition in sodium-depleted rats.

Clearances of inulin (CIn) and p-aminohippurate (CPAH) were measured in four groups of rats before and after intravenous administration of acetylsalicylic acid (ASA): 1) controls, on normal Na intake, 2) captopril-treated (30 mg.kg-1.day-1) on normal Na intake, 3) Na depleted, and 4) Na depleted, captopril-treated. In Na-depleted animals, CIn and CPAH were similar to controls but decreased significantly with ASA. In Na-depleted, captopril-treated rats, CPAH was slightly decreased, but CIn was significantly reduced (P less than 0.01). Both were not affected by ASA. Urine output was unchanged and the kidneys appeared normal on histological examination. The production of prostaglandins E2 (PGE2), F2 alpha (PGF2 alpha), and thromboxane B2 (TxB2) was measured in isolated glomeruli, cortical tubule suspensions, and medullary and papillary slices. Captopril increased PGE2 production by glomeruli and PGF2 alpha and TxB2 synthesis in papillary slices. Na depletion selectively enhanced the production of PGE2 by glomeruli and papillae. In contrast, the synthesis of prostanoids was significantly decreased in captopril-treated, Na-depleted rats. These findings suggest that in this model, functional nonoliguric renal failure may be related to abnormalities of prostanoid synthesis.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1987

Increased drainage volume in intermittent peritoneal dialysis using a two-bag, low hydrostatic pressure drainage system.

Adequate drainage volume (DV) is a prerequisite for long-term success of intermittent peritoneal dialysis (IPD). Ultrafiltration (UF) is basically determined by the interplay of two major forces: a driving osmotic force created by a hyperosmolar dialysate solution versus an opposing force--the intraperitoneal hydrostatic pressure. Conventional drainage procedures (CS) are capable of achieving a fluid volume of 3 L per bag. We found that this intrabag volume corresponds to an intrabag hydrostatic pressure of 60 cm water. Because this drainage system is closed, the intrabag hydrostatic pressure reflects intraperitoneal hydrostatic pressure. A low-pressure system (LPS) was devised to evaluate the possible influence on DV of reducing HP. Our results show that such LPS does indeed significantly improve DV, using a decreased number of exchanges. The residual volume and its glucose concentration (in a 1.5-g/dl exchange) were measured with CS. When followed by an 4.25-g/dl exchange, an 11% reduction in glucose concentration was evident. Thus, the osmotic driving force may also be impaired by incomplete drainage. To obtain maximal DV during IPD, a LPS should be used. This could be achieved by using 2 L dialysate in 3-L bags.

Aged↗
PubMed1987

IgM nephropathy: morphological study related to clinical findings.

This study describes 10 cases of IgM nephropathy in whom the main morphological findings consisted of diffuse mesangial deposition of IgM and varying degrees of mesangial cell proliferation. In addition, focal segmental sclerosis was present in 1 patient and global sclerosis in another. An ill-defined electron-dense deposit was seen within the mesangial area in 1 case. Except for 1 patient, who had hematuria only, all suffered from nephrotic syndrome without deterioration of renal function. In view of the constant and characteristic finding of a diffuse mesangial IgM deposition, it is suggested that this form of nephropathy constitutes an entity separate from focal glomerulosclerosis or minimal change disease.

Adolescent↗
PubMed1986

Natriuretic response to i.v. saline loading after acute poststreptococcal glomerulonephritis.

The outcome of acute poststreptococcal glomerulonephritis (APSGN) is still controversial. Whereas many studies show a good prognosis, particularly in children, late morphologic and functional renal abnormalities have been described. To verify this latter finding, we evaluated the sodium handling of the kidney several years after APSGN. Eleven subjects (9 children and adolescents and 2 adults) were studied 2 to 3 years after APSGN. At the time of the study all patients were well, without pathologic urinary findings and with normal blood pressures. Five healthy subjects (3 adults and 2 children) served as controls. Following two control periods of 30 min, an i.v. saline load (2.5% NaCl, 1 l/1.73 m2 body surface area) was administered over 45 min. Sodium excretion was measured during the control and salt-loading periods, and during four additional 30-min collection periods. No exaggerated natriuresis was found. We therefore conclude that epidemic APSGN in Israel carries not only an excellent clinical but also a good renal functional prognosis.

Adolescent↗
PubMed1985

Acute renal failure in a burn patient: the advantages of continuous peritoneal dialysis.

An 8-year-old girl sustained 65-70 per cent body surface area burns when her clothes caught fire. Two weeks later, she developed acute renal failure (ARF) and needed dialysis therapy. The extensive, infected burn area prevented the establishment of a safe vascular access for haemodialysis. Continuous peritoneal dialysis proved to be a valid alternative form of treatment and even had advantages over haemodialysis. Large amounts of fluids, calories and electrolytes could be administered via the peritoneal route. This facilitated the treatment of the catabolic state of the uraemic burn patient and served to correct the electrolyte losses via the skin. Peritoneal dialysis is a valuable adjunct to the treatment of acute renal failure in burn patients who need renal replacement therapy.

Acute Kidney Injury↗
PubMed1984

Dialysis-induced hypoxemia. Continuous monitoring of blood oxygen and carbon dioxide tension in children.

We report our experience with continuous, transcutaneous monitoring of capillary oxygen and carbon dioxide tension (PtcO2, PTlcCO2 ) during the entire length of hemodialysis treatment in 8 pediatric patients. The relative changes in PtcO2 and PtcCO2 observed with this method were in accordance with those reported in the literature, obtained with frequent arterial blood sampling. There was a temporary fall of PtcO2, averaging 26.2% after 2h of dialysis, with a concomitant rise of PtcCO2 of 9.9%. The noninvasive, transcutaneous measurement of PtcO2 and PtcCO2 is a reliable and valuable adjunct for the monitoring of the dialysis patient who is prone to develop hypoxemia. It is particularly useful in the very young.

Adolescent↗