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Biomedical subjects

A Yaari

Publications and source records attributed to A Yaari.

At least 37 records · Page 2Linked to original sources
PubMed1993

Increased neutrophil function induced by bile duct ligation in a rat model.

Neutrophil function was studied in rats with common bile duct ligation. Superoxide production stimulated by phorbol myristate acetate, opsonized zymosan or formyl-methionyl-leucyl-phenylalanine; phagocytosis; and chemotaxis were significantly greater in neutrophils from rats with common bile duct ligation than in sham-operated control rats. Enhanced neutrophil activity was observed within 12 hr of bile duct ligation; it remained increased during the 15-day study. Preincubation of neutrophils from control rats with sera of rats with common bile duct ligation did not increase superoxide generation. This suggests that the high superoxide production observed in neutrophils of rats with common bile duct ligation was not an immediate effect of the serum. Neutrophils of rats with portal vein ligation exhibited normal activity, indicating that portal systemic shunting per se is not the underlying mechanism for increased activity. The elevated levels of AST and alkaline phosphatase, indicating liver damage, that appeared within 12 hr of bile duct ligation correlated with the increased superoxide generation.

Animals↗
PubMed1992

Bromosulfophthalein disposition in chronically bile duct obstructed rats.

The disposition of bromosulfophthalein was studied in chronically bile duct obstructed rats. In this model a catheter was inserted into the common bile duct and the distal tip was sealed. Resumption of bile flow was achieved with great ease. Obstruction of bile duct for 18 days in rats resulted in elevated bilirubin, ALT, AST, and alkaline phosphatase levels. Portal hypertension developed within this period (11.6 +/- 0.5 in obstructed rats vs. 8.6 +/- 0.6 mm Hg in sham-operated group). After the bile duct obstruction was opened, the half-life time for elimination of bromosulfophthalein (42.30 +/- 6.47 min) was longer than in sham-operated rats (21.23 +/- 3.34 min). Plasma clearance was reduced by 70% in bile duct obstructed rats. In spite of increased bile flow rate, biliary excretion of the dye was reduced by 40% in chronically bile duct obstructed rats. Hepatic glutathione levels were significantly reduced by 20% in this model. The specific activity of glutathione S-transferase with chlorodinitrobenzene and styrene oxide, as substrates, was reduced by 50% and 30%, respectively. However, the percent of conjugated bromosulfophthalein in bile was similar to that of sham-operated rats.

Alanine Transaminase↗
PubMed1991

Hemodynamic characterization of conscious and ketamine-anesthetized bile duct-ligated rats.

The present study was conducted to characterize the hemodynamic alterations in common bile duct-ligated (CBDL) rats under ketamine anesthesia and in the awake restrained state. Hemodynamic studies using the radioactive microspheres technique were performed 17.6 +/- 0.6 (SE) days after bile duct ligation or sham operation. CBDL rats had lower mean arterial pressure, reduced systemic and renal resistance, and increased renal blood flow compared with sham-operated rats. This was found both in the conscious and anesthetized states. Anesthetized CBDL rats had higher portal pressure (13.2 +/- 0.5 vs. 9.2 +/- 0.4 mmHg; P less than 0.001) and lower splanchnic arteriolar resistance (15.4 +/- 1.3 vs 26.8 +/- 4.6 mmHg.ml-1.min.100 g body wt; P less than 0.05) than sham-operated rats. Portosystemic shunting was 52.3 +/- 11.7% in CBDL and negligible in sham-operated rats. The last three parameters could not be measured in conscious animals. Total peripheral resistance was lower in the conscious than in the anesthetized state, diverting a higher fraction of cardiac output at the expense of splanchnic organs and leading to a significant reduction of portal venous inflow in sham-operated but not in CBDL rats [3.36 +/- 0.47 vs. 5.38 +/- 0.65 (P less than 0.05) and 5.33 +/- 0.58 vs. 6.34 +/- 0.37 ml.min-1.100 g body wt-1 (P = NS), respectively]. These findings indicate that CBDL and normal rats respond differently to anesthesia and restraint. Because the restrained state is stressful and studies in anesthetized animals are technically simpler, provide additional information such as portal pressure and portosystemic shunting, and diminish animal suffering, we suggest that hemodynamic studies in rats, using the microsphere technique, should be preferably performed under ketamine anesthesia.

Anesthesia, General↗
PubMed1991

The effectiveness of a layered baseplate training aid in the preclinical instruction of second-year dental students.

The effectiveness of the Cavidrill baseplate in the training of second-year dental students in cavity preparations in primary ivorine teeth was assessed. The preclinical class of 112 students was divided into four groups: Cavidrill-only group, two groups combining Cavidrill training with traditional typodont training, and a typodont-only group. The Cavidrill baseplate was found not to improve the students' performance in cavity preparation when assessed on midterm and final examinations.

Dental Cavity Preparation↗
PubMed1990

Intrinsic potential for high fetal hemoglobin production in a Druz family with beta-thalassemia is due to an unlinked genetic determinant.

The mechanism for elevated production of fetal hemoglobin (Hb F) in a Druze patient with beta zero-thalassemia intermedia was investigated. Heterozygous family members exhibited normal Hb F levels, suggesting that the increase in gamma-gene expression in the propositus may be partly due to anemic stress. Erythroid progenitors of these family members cultured in vitro [burst forming units (erythroid); (BFUe)] showed elevated synthesis of Hb F, indicating the existence of a genetically determined intrinsic capacity for high Hb F production in this family. The propositus was found to be homozygous for a IVS2-position 1 mutation, on the background of Mediterranean haplotype I, which is not known to be linked to high Hb F production. Moreover, extensive molecular studies of the beta-globin gene cluster, including sequence analysis of the promoter regions of the gamma-globin genes, did not reveal any cis- actin mechanism that could account for the high Hb F production in the propositus. A young niece of the propositus with beta zero-thalassemia major was recently discovered, who was homozygous for the same beta-globin allele and haplotype as the propositus. However, unlike her uncle, she does not have a high Hb F level and presents with a severe clinical course. Her inability to produce high Hb F suggests that the genetic determinant for increased gamma-gene expression in the propositus is unlinked to the beta-globin gene cluster.

Adolescent↗
PubMed1989

Serum and effluent lysozyme (muramidase) activity in CAPD patients.

The elevated serum lysozyme activity in 13 chronic renal failure patients (n = 26) dropped significantly during their first three months of CAPD and subsequently returned to initial levels. When compared with peritoneal mass transfer of lysozyme and serum creatinine levels, a distinct correlation was observed between these and the fluctuations in serum lysozyme activity recorded up to three years of CAPD (r = 0.319, P less than 0.05 and r = 0.425, P less than 0.025, respectively). A notable drop in the mass transfer of this low molecular weight protein took place after the first hour of dialysis. We concluded that long-term CAPD does not affect serum lysozyme activity and that passive loss across the peritoneal membrane could account for the lysozyme found in the effluent fluid.

Adolescent↗
PubMed1986

Changes in theophylline metabolism during postnatal development in rat liver slices.

The metabolism of theophylline was studied in liver slices of young and adult rats. Theophylline and six metabolite fractions were recognized in adult liver by thin-layer radiochromatography and high performance liquid chromatography: 1-methyluric acid; 1-methylxanthine; 1,3-dimethyluric acid and/or 3-methylxanthine; caffeine; a uracil derivative and two unknown polar compounds. Preincubation with caffeine or theobromine inhibited theophylline metabolism. Allopurinol decreased the formation of three metabolite fractions but markedly increased the production of 1-methylxanthine. SKF 525-A inhibited the overall metabolism of theophylline. The specific activity of the enzyme system was 3.2 +/- 0.4 nmoles X (g liver)-1 X hr-1 in the 4- to 5-day-old rat and increased to a peak of 25.7 +/- 1.7 in the 28-day-old; values for Km and Vmax in the 7- and 28-day-olds were 132.1 and 67.5 microM, and 23.9 and 52.1 nmoles X (g liver)-1 X hr-1 respectively. Theophylline and the same six metabolites were identified in young and adult rats, but the development pattern was not uniform. Peak age-related activity and involvement of mixed-function oxidase system are features which are common to theophylline and caffeine metabolism. Xanthine oxidase played a role in theophylline metabolism. Formation of caffeine from theophylline was not dependent on a lack of activity of other pathways.

Allopurinol↗
PubMed1986

Urinary metabolites of caffeine in the premature infant.

Caffeine metabolites in urine from premature infants were analysed by TLC and HPLC. Caffeine, dimethyluric acids, mono- and dimethylxanthines and, for the first time, a uracil derivative (6-amino-5-[N-methylformylamino]-1,3-dimethyluracil) were identified.

Biotransformation↗
PubMed1986

EMC virus infection in baboons as a model for studies on antiviral substances.

EMC virus causes a lethal infection in baboon monkeys within 4-8 days following subcutaneous injection with 10(4)-10(8) pfu of virus. The infection is accompanied by viremia, invasion of heart muscle and of brain. Monkeys infected with 10(6) pfu of EMC virus were treated with human leukocyte interferon. The interferon was injected intramuscularly first 0, 0.5, 6 and 24 h post-infection, then twice daily with a dose of 3 X 10(6) units for 5 consecutive days. All the monkeys treated with interferon remained alive and healthy. Animals infected with EMC virus, but not treated with interferon died within 6 days with evidence of myocarditis. The EMC virus-interferon interaction in baboon monkeys seems to provide a useful primate model system for testing the prophylactic and therapeutic antiviral activity of interferons or other antiviral substances.

Animals↗
PubMed1986

1,3,8-Trimethylallantoin: a major caffeine metabolite formed by rat liver.

The formation of 1,3,8-trimethylallantoin from caffeine is demonstrated for the first time in vitro in rat liver slices. This compound constitutes 15% of total in vitro metabolites. With this identification, all the metabolic pathways of caffeine shown in vivo (N-demethylation, oxidation to uric acids and formation of uracil and allantoin derivatives) are demonstrated in vitro.

Allantoin↗
PubMed1979

Myeloproliferative disorders terminating in acute micromegakaryoblastic leukaemia.

Two cases of myeloproliferative disorder--one of myelofibrosis with agnogenic myeloid metaplasia and one of chronic granulocytic leukaemia terminating in acute micromegakaryoblastic leukaemia--are presented. The clinical course is described, and results are reported of morphological, cytometric, cytochemical and cytogenetic studies, as well as cell culture of blood cells in soft agar and in fluid medium.

Adolescent↗
PubMed1977

Semiquantitative cytochemical estimation of beta-glucuronidase activity in peripheral lymphocytes in healthy human subjects.

A semiquantitative cytochemical evaluation of beta-glucuronidase activity in peripheral lymphocytes in 123 normal sybjects was made. It was found that the enzymatic activity was influenced by age but not by sex. Activity was weak in newborn infants but increased with age and reached maximal values in old subjects. Age should therefore be taken into consideration when the enzyme activity is evaluated.

Adolescent↗