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Biomedical subjects

D Schwartz

Publications and source records attributed to D Schwartz.

At least 307 records · Page 17Linked to original sources
PubMed1984

Endocarditis caused by Actinobacillus actinomycetemcomitans.

The first two cases of Actinobacillus actinomycetemcomitans endocarditis in Israel are reported. One involved a 67 year old woman with mitral insufficiency and the other, a 48 year old alcoholic male with bioprosthetic mitral valve. The organism grew in three of seven and seven of fourteen blood culture specimens, taken during the first two or three days of hospitalization respectively. Blood cultures became positive after incubation for seven days. The first patient recovered after therapy with penicillin and an aminoglycoside, and the second one is still being treated. Previously described cases of Actinobacillus actinomycetemcomitans endocarditis are reviewed.

Actinobacillus Infections↗
PubMed1984

Renal arachidonic acid metabolism and cellular changes in the rabbit renal vein constricted kidney: inflammation as a common process in renal injury models.

The process of renal inflammation was examined using the partial renal vein constricted rabbit kidney ( RVC ) as a model. Forty eight hours of partial renal vein constriction in the rabbit was associated with an increase in prostaglandin (PG) and thromboxane (Tx) production. The ex vivo perfused RVC kidney showed an enhanced time-dependent increase in PG and Tx production in response to bradykinin stimulation when compared with the unaltered contralateral ( CLK ) or normal kidney. At 6 hrs of perfusion bradykinin stimulation released 2950 +/- 350 ng PGE2, 61 +/- 15 ng TxB2 from the RVC , and 225 +/- 85 ng PGE2 and undetectable TxB2 from the CLK . Histological examination of the RVC cortex showed an increase in fibroblast-like cells, a modest increase in the interstitial space and an appearance of macrophages and lymphocytes not seen in the normal or CLK . Endotoxin has been reported to stimulate macrophages in culture to produce PGE2 and TxB2. Endotoxin (100 ng) stimulation of the perfused RVC kidney caused an immediate, followed by a chronically increasing, release of PGs and Tx. Two hours after endotoxin injection 50 ml of effluent from the RVC contained 1450 +/- 107 ng PGE2 and 15.0 +/- 4.5 ng TxB2. Other animals of renal inflammation (e.g., the hydronephrotic kidney, chronic glomerulonephritis) also show the histological appearance of macrophages. In addition, hydronephrotic kidneys undergo fibroblast proliferation and changes in arachidonic acid metabolism similar to that we observed in the RVC . This work suggests that the inflammatory process (mononuclear cell infiltration, fibroblast-like cell proliferation, and accompanying changes in arachidonate metabolism is common among different forms of renal injury.

Animals↗
PubMed1984

Metabolic processing of 2-acetylaminofluorene by microsomes and six highly purified cytochrome P-450 forms from rabbit liver.

Kinetic analysis of oxidative metabolism of 2-acetylaminofluorene (AAF) was studied in control and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced microsomes and with six highly purified cytochrome P-450 isoenzymes from rabbit liver. Kinetic parameters were defined for 7-, 5-, 3-, 1- and N-hydroxylations of AAF. 7-Hydroxylation was best defined by a two enzyme system, displaying a high affinity and relatively low capacity and a low affinity high capacity components in both control and TCDD induced microsomes. All the purified cytochrome P-450 isoenzymes were capable of catalyzing the 7-hydroxylation of AAF and, with the exception of form 4, this was the only oxidation on the AAF molecule catalyzed by these forms. It is probable that forms 1, 4 and 6 accounted for a substantial part (greater than or equal to 25%) of total metabolic capacity corresponding to the high affinity component of 7-hydroxylation, whereas forms 3b and 3c accounted for less than 5% of the metabolic capacity displayed by the low affinity component in control microsomes. However, forms 4 and 6 could account for greater than 90% of the metabolic capacity of the high affinity component of 7-hydroxylation in TCDD microsomes, whereas the form(s) responsible for the metabolic capacity of the low affinity component were not identified. Each of the 1-, 3-, 5- and N-hydroxylations were best defined by a single enzyme system in both control and TCDD microsomes (3- and 5-hydroxylations could not be defined in TCDD microsomes). Close agreements were found between the apparent Km for N-hydroxylation in control, TCDD induced microsomes and with form 4. alpha-Naphthoflavone inhibited AAF N-hydroxylation to a similar extent in control and TCDD microsomes and in form 4. These date indicate that: a subpopulation of cytochrome P-450 isoenzymes, which includes all the purified P-450 forms tested in the present study, is solely involved in detoxification (i.e., 7-hydroxylation) of AAF, and as such probably behave as a functional unit in vivo; modulation of cytochrome P-450 content by inducers such as TCDD results in emergence of relatively few cytochrome P-450 isoenzymes that can account for most of the oxidative metabolism of AAF; and a single cytochrome P-450 isoenzyme (i.e., form 4) is responsible for catalyzing N-hydroxylation of AAF, the first and the obligatory step in the metabolic activation of this carcinogen.

2-Acetylaminofluorene↗
PubMed1984

Exercise intolerance in patients with chronic heart failure: role of impaired nutritive flow to skeletal muscle.

The maximal exercise capacity of patients with chronic heart failure is frequently reduced. To investigate whether this exercise intolerance is caused by inadequate nutritive flow to skeletal muscle, we compared cardiac outputs, leg blood flow, and leg metabolism during maximal bicycle exercise in seven patients with normal maximal oxygen uptake (VO2) (greater than 20 ml/min/kg; group A), eight patients with heart failure and moderately reduced maximal VO2 (15 to 18 ml/min/kg; group B), and eight patients with heart failure and markedly reduced maximal VO2 (less than 14 ml/min/kg; group C). As the severity of exercise intolerance increased from group A to group C there was a progressive decline in cardiac output and leg blood flow at any given workload accompanied by a progressive decline in maximal cardiac output (liters/min) (A, 12.4 +/- 1.0; B, 8.7 +/- 0.9; C, 5.5 +/- 0.7), maximal leg flow (liters/min) (A, 4.0 +/- 0.3; B, 2.6 +/- 0.4; C, 1.4 +/- 0.2), and maximal leg VO2 (ml/min) (A, 564 +/- 49; B, 403 +/- 41; C, 213 +/- 35 ml/min). All patients terminated exercise because of severe leg fatigue. At termination of exercise, all three groups exhibited similar marked levels of leg O2 extraction (%) (A, 80 +/- 2; B, 83 +/- 3; C, 89 +/- 1) and high femoral-arterial lactate gradients (mg/dl) (A, 15.4 +/- 2.6; B, 18.3 +/- 3.5; C, 19.2 +/- 3.6), suggesting that exercise was limited when a critical level of muscle underperfusion was reached. These data suggest that the reduced maximal exercise capacity of patients with chronic heart failure is primarily due to impaired nutritive flow to skeletal muscle and resultant muscular fatigue.

Adult↗
PubMed1983

Sterility and fecundability estimation.

The percentage of steriles and the fecundability of non-steriles among a given population can be estimated by a probabilistic model from observations made on delays to first conception. The maximum likelihood method of estimation that was used takes into account all available information, though some of these observations may be incomplete due to a variable follow-up amongst the couples. The model is illustrated with data provided by a prospective study.

Female↗
PubMed1983

Campylobacter enteritis in normal and immunodeficient children.

Campylobacter fetus subspecies jejuni (CBJ) has been recently recognized as a common pathogen in bacterial gastroenteritis in children. During a period of 16 months, 51 cases of C fetus subspecies jejuni gastroenteritis were diagnosed. Five of the children in whom the cases were diagnosed were previously known to be immunodeficient: two had X-linked agammaglobulinemia, one had agammaglobulinemia, one had combined immunodeficiency, and one had transient hypogammaglobulinemia. Average duration of fever and diarrhea was longer in the five immunodeficient children (15 and 23 days, respectively) compared with the normal children (four and five days, respectively). Excretion of C fetus subspecies jejuni in stool persisted for 20 to 27 days in four of the immunodeficient children and for one year in the fifth, whereas normal children excreted C fetus subspecies jejuni for only four to 16 days. Campylobacter fetus subspecies jejuni may be added to the list of bacterial pathogens most likely to infect immunodeficient children, especially those with a defect of the humoral system.

Campylobacter Infections↗
PubMed1983

Isolation and mapping of cDNA hybridization probes specific for ecotropic and nonecotropic murine leukemia proviruses.

To study the structure of murine leukemia proviruses in AKR mice by Southern hybridization, we have isolated and mapped ecotropic AKV and nonecotropic MCF-derived cDNA restriction fragments. The ecotropic-specific probes originate from four regions of the AKV genome which include the corresponding recombinant region of two MCF viruses (VI-36 and 247). We also isolated two nonecotropic probes from the recombinant region of MCF V1-36. The probes were characterized by (i) mapping of restriction fragments at the 3' end of AKV and MCF V1-36 by a two-dimensional gel strategy, (ii) hybridization of restriction fragments to the related viral RNA genomes followed by electrophoresis, (iii) two-dimensional fingerprinting of single-stranded restriction fragments, and (iv) DNA sequence analysis of the ecotropic probes. The ecotropic AKV and nonecotropic MCF probes discriminate between two populations of endogenous murine leukemia viruses and show that the MCF viruses are not present in the germ line of AKR mice.

AKR murine leukemia virus↗
PubMed1983

Semen characteristics as a function of age in 833 fertile men.

The relationship between age and semen characteristics has been studied; any effect due to the influence of the length of abstinence preceding ejaculation was eliminated. There is an improvement in semen characteristics up to 25 years of age, followed by a leveling off and a subsequent decrease. This variation is not significant as far as the sperm count, semen volume, and the total number of spermatozoa are concerned. The variation, although small, is highly significant for the morphologic characteristics and prefreeze and postthaw motility. The values for the older subjects were significantly lower for postthaw motility in the group 36 to 40 years of age, in the group 41 to 45 years of age for morphologic normality, and in the group 46 to 50 years of age for prefreeze motility. The lower values in the group 21 to 25 years of age are particularly noticeable with regard to morphologic characteristics. The same curve is encountered in the variation with age of each abnormal form, but the most marked variation is found in the increased percentage of coiled tails, which first appears in the group 36 to 40 years of age.

Adult↗
PubMed1983

Studies on the blood-aqueous barrier after argon laser photocoagulation of the iris.

Breakdown and re-establishment of the blood-aqueous barrier (BAB) was studied following laser irradiation to the rabbit iris by quantitating leakage of protein, fluorescein, and fluorescein-labeled dextran (FLD-70, MW 70,000) into the aqueous humor. Breakdown of the BAB was more prolonged in pigmented than albino animals, possibly due to the increased laser energy absorbed by the pigmented iris. Fluorophotometry appeared to be a more sensitive method for evaluating BAB breakdown than aqueous protein measurements, and small molecule leakage (fluorescein) appeared to be more sensitive than macromolecule leakage (FLD-70). The noninvasive method of evaluating the BAB proved equally as effective as measuring aqueous protein content in assessing the sensitivity of laser-induced trauma to the ameliorating effect of the nonsteroidal anti-inflammatory agent indomethacin.

Animals↗
PubMed1983

NIH conference. Type III hyperlipoproteinemia: diagnosis, molecular defects, pathology, and treatment.

Type III hyperlipoproteinemia is characterized by increased plasma levels of triglycerides and cholesterol, palmar-tuberoeruptive xanthoma, and premature cardiovascular disease. Three major classes of molecular defects will predispose patients to develop type III hyperlipoproteinemia: a deficiency in apolipoprotein E, a structural defect in the E apolipoprotein, and a functional defect in the liver receptor system. Most patients with type III hyperlipoproteinemia have a structural defect in apolipoprotein E associated with increased synthesis and decreased catabolism of apolipoprotein E, delayed catabolism of chylomicron remnants, and development of plasma lipoprotein abnormalities characteristic of type III hyperlipoproteinemia. Analysis of cardiovascular disease in patients with type III hyperlipoproteinemia showed extensive coronary and peripheral vascular atherosclerosis indistinguishable from the atherosclerosis of non-hyperlipidemic and other dyslipoproteinemic patients. The xanthoma and elevated plasma cholesterol and triglyceride levels in patients with type III hyperlipoproteinemia respond to dietary and drug therapy.

Adolescent↗
PubMed1983

Meningitis and bacteremia due to Bacillus cereus. A case report and a review of Bacillus infections.

A patient with meningitis and bacteremia due to Bacillus cereus is described. The patient had transsphenoidal hypophysectomy for chromophobe adenoma, complicated by rhinorrhea, which was corrected by subarachnoid drainage. Three weeks after removal of the drain, the patient presented with meningitis and died the following day. The causative organism was identified as B. cereus. The literature on Bacillus infections is reviewed with special attention to severe infections. A modified classification is proposed, dividing infections into superficial, closed-space and systemic ones. Sixty-one previously reported cases of systemic Bacillus infections are reviewed according to type of infection (endocarditis, meningitis or pulmonary infection), and the underlying conditions, ways of acquiring the infection, clinical picture and mortality are discussed.

Aged↗
PubMed1983

Bacteremia in hospitalized children.

Among 7,205 children hospitalized in the Pediatric Service at the Rokach (Hadassah) Hospital during 1980 and 1981, 44 were found to be bacteremic. The most common pathogen was Streptococcus pneumoniae, followed by Salmonella, Staphylococcus, Klebsiella and others; 52% of the isolates were gram-negative. The most common focus of infection was the respiratory tract, followed by the gastrointestinal and urinary tracts. Almost half of the bacteremic children were under 2 years of age. Other data, such as predisposing conditions and mortality, and whether the bacteremias were hospital acquired, are also analyzed. All of the findings are discussed and compared to the findings from the few similar studies in the literature.

Adolescent↗