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Biomedical subjects

N Kariv

Publications and source records attributed to N Kariv.

At least 37 records · Page 2Linked to original sources
PubMed1988

Clearance of Serratia marcescens from blood in mice: role of hydrophobic versus mannose-sensitive interactions.

In the present study, we examined the potential roles of cell surface hydrophobicity and mannose-sensitive (MS) interactions in blood clearance of Serratia marcescens in mice. Hydrophobic strain RZ, partially hydrophobic mutant 3162, and nonhydrophobic mutant 3164 were coinoculated into BALB/c male mice, and blood samples were plated out at different time intervals; colonies of the three strains were distinguished by their different morphologies. All three strains were cleared from the blood stream at similar rates, despite their large relative differences in cell surface hydrophobicity. Clearance from blood was subsequently studied by coinoculating two clinical isolates which differ in their abilities to adhere via MS interactions. MS+ strain 1785 was cleared much more rapidly than MS- strain 3255; moreover, in the presence of D-mannose, clearance of strain 1785 was inhibited to a rate similar to that of MS- strain 3255. When D-glucose was substituted for D-mannose, inhibition was not observed. The results suggest that MS, rather than hydrophobic, interactions are primarily responsible for the rapid clearance of S. marcescens from blood observed.

Animals↗
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↗
PubMed1988

Hidden loop jejunostomy--an experimental model.

A hidden loop jejunostomy, the placement of a proximal small bowel loop under the skin of dogs, is described. A feeding tube was inserted in the loop at a later date, which enabled feeding for at least 6 weeks. This procedure was well tolerated by the 10 dogs involved in this experimental model. It should be considered as a possible surgical procedure at initial explorative laparotomy in patients with advanced cancer originating at the gastric cardia or esophagogastric junction.

Animals↗
PubMed1988

Vascular placental insufficiency in the rabbit. Changes in creatine kinase and adenylate kinase activities in fetal tissues.

Vascular placental insufficiency is considered a common pathogenic factor in human intrauterine growth retardation. To mimic this condition, the rabbit, a 'perinatal brain developer' was utilized as an experimental model. Ischemic conditions were achieved by total ligation of approximately 30% of the uteroplacental vessels of half of the fetuses in each pregnant rabbit in the last third of gestation. The change in activity of the brain type isozyme of creatine kinase (CKBB), involved in energy regeneration and regulation, was assessed as a response marker to tissue ischemia in rabbit tissues: cerebellum, cerebrum, kidney, liver and placenta. A significant transient increase in CK-specific activity was found in the kidney and the cerebellum but not in the other organs tested, at 24 and 48 h after ligation. This increase was not seen with adenylate kinase, another enzyme involved in energy regeneration and regulation. It is proposed that an increase in CK-specific activity could serve as a metabolic marker of vascular insufficiency in rapidly developing tissues, representing part of a compensatory mechanism to overcome an energetic gap induced by ischemia.

Adenylate Kinase↗
PubMed1988

Penetrating keratoplasty in rabbits with herpetic keratitis treated with poly I:C.

Penetrating keratoplasties were performed in which grafts were exchanged between normal rabbits and rabbits previously infected with Herpes simplex virus (HSV). Clear grafts were obtained when surgery was performed during the latent stage of the disease (3 months after HSV inoculation). Polyinosinic acid: polycytidylic acid (poly I:C) was administered before and after keratoplasty when the rabbits had active herpetic keratitis. Clear grafts were obtained when the rabbits were inoculated with HSV and treated 18 hours later with poly I:C, which was continued until two weeks before keratoplasty. This treated group had a rapid decrease in HSV titer, inhibition of the migration of HSV from the infected cornea to the trigeminal ganglia, and a decrease in antibody titer to HSV in the sera. In rabbits inoculated with HSV, subjected two weeks later to keratoplasty, and then treated with poly I:C, three quarters of the graft rejections were milder than those in the control group.

Administration, Topical↗
PubMed1987

Possible role of fibrinogen in the aggregation of white blood cells.

In order to verify whether leukocyte aggregation correlated with aggregation of other cellular elements during inflammation, we examined the state of leukocyte adhesiveness/aggregation (LAA) in the peripheral blood and red cell aggregation. Correlation was found to be significant as was the correlation between LAA and fibrinogen, and with the fibrin/fibrinogen degradation products concentration during various inflammatory states. In vitro leukocyte aggregation was decreased when the cells were suspended in autologous heat defibrinogenated plasma as compared to cells suspended in autologous native plasma. Heat aggregated fibrinogen but not native fibrinogen caused leukocyte aggregation in vitro. Finally, Arvin defibrinogenation in rabbits reduced the state of LAA in endotoxinemic rabbits. Integrating all this information, we assume that fibrinogen participates not only in the aggregation phenomena of red cells and platelets, but also in those of leukocytes.

Animals↗
PubMed1987

Effects of sodium loading on the renal synthesis of prostanoids in the rat.

1. The production of prostaglandin (PG) E2, F2 alpha and thromboxane B2 (TXB2) by isolated glomeruli, cortical tubular suspensions and medullary and papillary slices was measured in normal Long-Evans rats 4, 8 and 14 days after starting on oral Na+ load and the results were compared with those of rats on a normal Na+ intake. 2. In glomeruli, PGE2 decreased at days 4 and 8, and returned to normal at 14 days. PGF2 alpha decreased only at day 4 and TXB2 decreased in all Na+-loaded animals. In cortical suspensions, a transient decrease of PGE2 was observed at day 4. In medullary slices, PGE2 and TXB2 decreased in all experimental periods. In contrast, in papillae, a significant increase of PGE2 was observed with Na+ loading at day 8, but PGF2 alpha and TXB2 did not change consistently. 3. Similar changes were observed in rats with hypothalamic diabetes insipidus (DI rats) Na+ loaded for 4 days, as compared with DI rats on a normal Na+ intake. 4. The results suggest that prostanoids participate in the renal adaptation to an increased Na+ intake, and that this response is relatively independent of the presence of antidiuretic hormone.

Animals↗
PubMed1986

NADH-dependent prostaglandin E2-9-ketoreductase activity and prostaglandin synthesis in the Brattleboro rat kidney: effects of the antidiuretic hormone.

The activity of prostaglandin (PG)E2-9-ketoreductase (9KR), an enzyme catalyzing the conversion of PGE2 to PGF2 alpha, was significantly increased in glomerular and cortical homogenates of diabetes insipidus (DI) rats, as compared to normal Long Evans (LE) rats, and did not change with ADH treatment. Medullary 9KR was similar in the three groups and papillary 9KR was increased, but not significantly, in both groups of DI rats. Km values for PGE2 and NADH were compared in the various compartments of the kidney. Levels of 9KR were not correlated with the PGE/PGF ratio in urine or supernatants. The synthesis of PGE2 and PGF2 alpha by isolated glomeruli was increased in DI rats. This was not reversed by ADH treatment, PGE2 synthesis increasing even further, especially in the presence of arachidonic acid. In contrast, medullary slices produced significantly less PGs in DI than in LE rats and returned to normal with ADH treatment. Papillary slices produced similar quantities of prostaglandins in all groups. The results do not support the concept that the alterations in PG synthesis observed in DI rat are related only to changes in 9KR activity, but do not exclude the possibility that the enzyme participates in the regulation of PG biosynthesis.

Animals↗
PubMed1986

Sodium intake as a determinant of urinary prostaglandin excretion. Studies in the Brattleboro rat.

In order to investigate the effects of changes in sodium (Na) balance on the renal production of prostaglandins (PG) E2 and F2 alpha in the absence of antidiuretic hormone (ADH), studies were performed in Brattleboro rats, without endogenous ADH, and in heterozygote Long Evans rats which served as controls. All rats received a diet virtually devoid of Na, with distilled water ad libitum, and Na intake was modified by adding different quantities of Na to the drinking water. Three groups were studied for each strain: normal Na intake, low Na intake and Na loading. At the end of a 14 day diet period, urinary PGE2 and PGF2 alpha were measured by radioimmunoassay in collections obtained for three consecutive days. In the Na depleted animals, both PGE2 and PGF2 alpha decreased. The PGE2/PGF2 alpha ratio (E/F ratio) was unchanged. In contrast, Na loading induced a significant decrease of PGE2 but PGF2 alpha increased, though not significantly. The E/F ratio was significantly decreased. The results were qualitatively similar in the presence or absence of ADH, but the Brattleboro rats, overall, excreted less PGs than controls. The results suggest that changes in Na balance are major factors influencing urinary PG excretion. These substances probably play a role in the modifications of Na handling by the kidney in different balance states.

Animals↗
PubMed1986

Effect of angiotensin II on prostanoid synthesis in isolated rat glomeruli.

The influence of angiotensin II (ANG II) on the synthesis of glomerular prostanoids is controversial, possibly because of the different methodologies employed. In order to assess this inter-relationship isolated rat glomeruli were incubated with and without shaking. The use of shaking during incubation significantly increased the amounts of prostanoid synthesized, most probably because of continuous non-specific activation of phospholipase (PLA2) activity. After preincubation in a non-shaking bath, ANG II was added for a second incubation period. A marked increase of prostaglandin (PG) E2, and, to lesser degree, of thromboxane (TX) B2 was noted, with no change on PGF2 alpha synthesis. These results show (a) that preincubation without shaking, by lowering the non-specific activation of the PLA2 activity, may unmask, in vitro, specific peptide stimulation, and (b) that ANG II, stimulating principally PGE2 synthesis, may modify the vasoactive status of the glomerular vasculature.

Angiotensin II↗
PubMed1985

The leukergy test in rheumatic diseases. New implications for an old test.

In order to assess the value of the leukergy test in which leukocytes aggregate in citrated whole blood, we examined 65 patients with various rheumatic conditions. In addition, plasma samples from 40 patients were examined for neutrophil aggregation activity in vitro. Results of the leukergy test were found to be in very good correlation with disease activity (P = 0.0001), whereas no increased neutrophil aggregation activity was found in the 40 plasma samples examined. The value of the leukergy test in assessing patients with rheumatic disease and its theoretical etiopathogenic role in these diseases are discussed.

Adult↗
PubMed1985

Effect of potassium loading on prostaglandin E2 and F2 alpha excretion in the Brattleboro rat.

In order to assess the relative roles played by potassium (K) and the antidiuretic hormone (ADH) on the renal production of prostaglandins (PG) E2 and F2 alpha, the 24 hour urinary excretion of these substances was measured in Brattleboro rats (devoid of ADH) and in control Long Evans heterozygote rats. Rats of each strain received either a normal K intake or a K load for 8 days. Urinary PGE2 and PGF2 alpha were measured by radioimmunoassay in three consecutive 24 h urine collections obtained after the above periods. K loading induced an increase in PGF2 alpha (p less than 0.01), PGE2 showing a non significant trend to decrease. The E/F ratio was decreased in K loaded animals. The changes were qualitatively similar in presence or absence of ADH, but animals with diabetes insipidus had lower levels of PGs than control animals. The results suggest the possibility that K loading induces an increase in the activity of the renal enzyme PGE2-9-ketoreductase. The resulting increase in PGF2 alpha could play a role in K excretion and this response is probably independent of ADH.

Animals↗
PubMed1985

Effect of sodium loading on the urinary excretion of prostaglandins E2 and F2 alpha in rats with hereditary diabetes insipidus (Brattleboro rats).

Current evidence suggests that the antidiuretic hormone (ADH) and changes in sodium balance influence renal prostaglandins (PGs). To separate these two mechanisms, the effect of sodium loading on the urinary excretion of PGE2 and PGF2 alpha was studied in female Brattleboro rats with diabetes insipidus (DIHO) and compared with that in female, age matched, heterozygous Long Evans controls (LEHE). Ten DIHO and ten LEHE rats had a normal sodium intake. In ten DIHO rats a 0.16% NaCl solution was supplied instead of drinking water for either 8 days (n = 5) or 14 days (n = 5). In two groups of LEHE rats, sodium loading was obtained with a 0.80% NaCl solution for the same study periods. Urine PGs were measured by radioimmunoassay in three 24 h urine collections for each rat. Urine PGs were significantly increased in the 8 day loaded but not in the 14 day loaded LEHE rats. In DIHO rats, a non-significant increase in both PGE2 and PGF2 alpha was present after 8 days of sodium loading, while PGE2 and the E/F ratio were decreased after 14 days of salt loading. The findings suggest that the natriuresis induced by sodium loading in the rat may be mediated in part by increased production of PGs. In addition, it seems that ADH plays a role in this response.

Animals↗
PubMed1984

Furosemide effect on penicillin induced convulsions.

Convulsions were induced in 20 cats by the administration of intravenous penicillin. Furosemide administered together and after penicillin failed to reduce the seizure activity. Penicillin brain concentrations were not reduced by furosemide. Penicillin induced seizures are not affected by furosemide.

Animals↗
PubMed1983

Leukocyte agglomeration test to reveal bacterial infections in mice.

A simple and rapid procedure was used to detecting covert bacterial infections in mice. The procedure was based on observations that bacterial infections were associated with clumping of leukocytes. A large drop of citrated venous blood was placed on a slide and allowed to spread. After fixation and staining the percentage of agglomerated leukocytes was determined by counting. Experimental urinary tract infections caused by either Escherichia coli or Proteus mirabilis served as a model to test the efficacy of the method. Elevation of leukocyte agglomeration was observed in these localized infections.

Animals↗
PubMed1982

The effect of poly I:C and IUDR on the inhibition of HSV in rabbit eyes.

The inhibition of herpetic keratitis by a combination of Poly I:C with DEAE-Dextran and IUDR was studied in rabbit eyes. This treatment was administered 72 h after HSV inoculation (daily) for 3 days and continued once daily for another 2-3 days. A significant improvement was detected in rabbit eyes beginning on the first day of treatment, and there was minimal scarring. This improvement in herpetic keratitis coincided with a decrease in the virus titer isolated from rabbit eyes and an increase in interferon titer detected in rabbit tears. The cornea and trigeminal ganglia of treated and control rabbits were tested in order to prove whether this combined treatment could inhibit the migration of HSV from the cornea to the trigeminal ganglia. During the active stage of the disease, HSV was isolated in a lower titer from the cornea of the treated rabbits and from the ganglia of only half of this rabbit group. During the latent stage of the disease, no HSV was isolated from the cornea of either rabbit group, but HSV was isolated from the ganglia explants of the treated rabbits in a somewhat lower titer than from the controls. This treatment administered 3 days after the virus inoculation could not prevent the migration of HSV from the infected cornea towards the trigeminal ganglia.

Animals↗
PubMed1981

Effects of parathyroid hormone on exocrine pancreatic secretion in parathyroidectomized dogs.

The effects of intravenous parathyroid hormone (PTH) on steady state Secretin-induced pancreatic secretion were studied in seven dogs before and after parathyroidectomy. Free flow of pancreatic juice was obtained by direct cannulation of the main pancreatic duct (the minor duct being ligated) : a gastric fistula prevented the entry of gastric acid into the duodenum. In the normal dog PTH caused a significant increase in volume and bicarbonate concentration, reciprocal change in chloride and no change in total protein concentration. The stimulatory effect of PTH was dose-dependent. In the parathyroidectomized dog, the basic Secretin-induced secretion was lower than the preoperative values, but PTH infusion caused a significant increase in volume of fluids and bicarbonate concentration, reciprocal change in chloride and no change in protein concentration. These results were not dependent on calcium blood level, and did not change after calcium injection to the hypocalcemic parathyroidectomized dog. It is suggested, that PTH may have a direct effect on pancreatic exocrine secretion.

Animals↗