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Biomedical subjects

D Schwartz

Publications and source records attributed to D Schwartz.

At least 217 records · Page 12Linked to original sources
PubMed1990

Risk factors for postvitrectomy fibrin formation.

We prospectively studied 194 patients undergoing vitrectomy between July 1988 and April 1989 to determine the incidence of postvitrectomy intraocular fibrin formation and the association of a variety of preoperative and intraoperative variables with the formation of severe postvitrectomy fibrin. Overall, 62 (32%) patients developed postvitrectomy fibrin; 25 (13%) had mild fibrin formation, 13 (6.5%) had moderate fibrin formation, and 24 (12.4%) had severe fibrin formation. By logistic multivariate analysis, preoperative factors that were independently predictive of severe fibrin formation included severe flare (P = .004), the presence of a previously placed scleral buckle (P = .001), and poor preoperative visual acuity (P = .007). Anterior epiretinal membrane dissection was the only intraoperative factor that was independently associated with an increased fibrin risk (P = .0003). A risk score derived from the multivariate analysis effectively categorized patients according to their likelihood of developing severe postvitrectomy fibrin. Results of this study may be useful in designing prophylactic interventions to decrease postvitrectomy fibrin formation.

Adult↗
PubMed1990

V region gene usage and somatic mutation in the primary and secondary responses to influenza virus hemagglutinin.

Most (80 to 90%) primary antibodies specific for the Sb site of influenza virus (A/PR/8/34) hemagglutinin share an Id (designated C4). Secondary antihemagglutinin(Sb) antibodies also exhibit the C4 Id although less frequently (10 to 15%). We have analyzed the V region nucleotide sequences of primary and secondary antibodies with the C4 Id. Primary C4 antibodies are encoded by the same Vk gene, belonging to the Vk8 group, usually rearranged to Jk5. The H chains are diverse, encoded by VH genes belonging to at least four different VH families, a variety of DH genes, and either JH2, JH3, or JH4. There is only one somatic mutation among seven Vk and two VH genes encoding primary C4 antibodies. Secondary C4 antibodies are also encoded by the same Vk8-Jk5 gene segment and by diverse VH genes. Additional heterogeneity in the secondary response is caused by somatic mutation.

Amino Acid Sequence↗
PubMed1990

Balloon aortic valvuloplasty: results of the Valvuloplasty and Angioplasty of Congenital Anomalies Registry.

Data from 204 children and infants who underwent aortic balloon valvuloplasty between 1982 and 1986, reported to the Valvuloplasty and Angioplasty of Congenital Anomalies Registry, were reviewed. Valvuloplasty was successful in 192 of 204 children, reducing the peak systolic left ventricular ejection gradient from 77 +/- 2 to 30 +/- 1 mm Hg, p less than 0.001. The same degree of aortic stenosis gradients reduction was noted in both the 38 children under 1 year of age and in the 166 children over 1 year of age. Significant complications included death, aortic regurgitation and femoral artery thrombosis or damage. The incidence of these complications correlated with the age of the child, the ratio of valvuloplasty balloon size/anulus size, or both. The data suggest that percutaneous balloon valvuloplasty provides effective acute relief of valvar aortic stenosis in both infants and children. However, long-term follow-up data are necessary before balloon valvuloplasty can be established as a treatment of choice for congenital valvar aortic stenosis.

Aortic Valve↗
PubMed1990

Zidovudine (azido dideoxythymidine) inhibits characteristic early alterations of lymphoid cell populations in retrovirus-induced murine AIDS.

Using flow cytometry technology and multiparameter analyses, we report early and characteristic alterations in lymphoid cell profile in spleen and lymph nodes due to LP-BM5 retrovirus disease (murine AIDS (MAIDS)) and the effect of azido dideoxythymidine, a nucleoside inhibitor, on these changes. MAIDS has been characterized by rapid and profound lymphoproliferation accompanied by hypergammaglobulinemia and immunosuppression. As early as 2 wk postinfection, there is a selective depletion of CD8+ cells whereas the total number of CD4+ cells increases throughout the first 8 wk of infection although the frequency is relatively stable. These population changes were partially delayed by oral AZT therapy for 6 wk postinfection. Ly-6C (AL-21) is expressed on roughly 50% of CD4+ and CD8+ cells in C57BL/6 mice. In MAIDS, the residual population of CD8+ cells is primarily Ly-6C+. The CD4+ cells have a transient increase in ratio of Ly-6C+/Ly-6C- cells at 2 wk postinfection but by 6 wk are primarily Ly-6C-. There was an increase in both the total number and percentage of Mac 1+ cells and a selective depletion of certain splenic B cell subpopulations. Azido dideoxythymidine delays these early population changes.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Chronic neuropsychological sequelae of occupational exposure to organophosphate insecticides.

The early (immediate and delayed) neurotoxic effects of acute organophosphate intoxication are well documented in the scientific literature; lack of recognition and inappropriate treatment of occupational poisonings continue. Less well understood is the potential development of chronic neuropsychological sequelae from exposures to insecticides. We undertook two cohort studies to assess chronic neuropsychologic effects of insecticide poisoning. Based, in part, on our clinical evaluation of several patients, these studies included: 1) a retrospective cohort study assessing function at least 1 year following moderate to severe poisonings among farm workers; and 2) a prospective cohort study assessing neuropsychological function before and after a season of organophosphate exposures among pesticide applicators. A typical case description, the study design, methodologic problems, and preliminary findings of these ongoing studies are presented.

Agricultural Workers' Diseases↗
PubMed1990

Hematopoiesis on cellulose ester membranes (CEM). XII. Effect of membrane enrichment by purified matrix proteins.

Cellulose ester membranes (CEM) were enriched with the following purified matrix proteins: collagen I, II, IV, proteoglycan and laminin. Fifteen milligrams of each were placed on CEM which were then folded into open-ended tubes implanted i.p. and s.c. CEM were removed after 3, 6 and 12 months and examined histologically. There was no evidence of hematopoiesis or new bone formation on the implanted, enriched CEM at any of the intervals examined. Collagen I and proteoglycan-enriched CEM showed evidence of increased sinusoid-like vascular structures.

Animals↗
PubMed1990

Use of synthetic oligonucleotide DNA probes for the identification of Bacteroides gingivalis.

Six different oligonucleotide probes complementary to the hypervariable regions of 16S rRNA of Bacteroides gingivalis were tested for specificity and sensitivity against 77 field strains of B. gingivalis and 105 strains of 12 other Bacteroides species. The data demonstrated that these probes were very specific (range, 0.85 to 1.00) and sensitive (1.00). Some limited cross-reactions with other Bacteroides species were observed. Four of these probes should be useful for rapid detection and identification of B. gingivalis.

Bacteroides↗
PubMed1990

Serious infectious complications of midsternotomy: a review of bacteriology and antimicrobial therapy.

49 patients with severe infectious complications of midsternotomy incision were treated at our referral center over a 3-year period. 43 species of microorganisms were identified in 38 patients, the most common being Pseudomonas aeruginosa (37%) and Staphylococcus aureus (30%). Most of the patients underwent aggressive debridement and chest wall reconstruction by muscle transposition in combination with antimicrobial therapy. Antimicrobial therapy was given perioperatively according to the in vitro susceptibility of the organisms. Treatment was continued beyond this period for 2-3 weeks in patients with extensive deep seated infection or in those with positive cultures from intraoperative specimens. Some patients needed a longer course of up to 6-8 weeks antimicrobial therapy because of insufficient response to the shorter course. In all, 45/49 patients had complete wound healing. 28 recovered within 2-5 weeks and 16 required a more protracted course with additional surgery in 8; 1 wound did not heal after 20 months and 4 patients died from non-infectious complications. Due to the lack of specific guidelines in the literature as to the proper choice and length of administration of antimicrobial therapy for midsternotomy wound infection, and in view of these favorable results, we recommend our protocol in the treatment of midsternotomy wound infection (in combination with appropriate surgery).

Anti-Bacterial Agents↗
PubMed1990

[Immunologic diagnosis and therapy in habitual abortion].

It is a crucial and yet unresolved problem of immunology, how the allogeneic fetus can escape the rejection of the maternal immune system. There is a lot of evidence that certain maternal immune reactions at an early stage of gestation are essential for fetal survival, but the precise mechanisms are unknown. Antibodies against fetal histocompatibility antigens are found in healthy pregnant women, whereas they are not demonstrable in the serum of patients with recurrent spontaneous abortions. Furthermore, if antibodies can be induced by leucocyte injections, a high percentage (60 to 85%) of patients have a next pregnancy without complications. In first studies, the passive transfer of antibodies by infusion of intravenous gammaglobulins has shown similar results.

Abortion, Habitual↗
PubMed1990

ELISA for Campylobacter jejuni antibodies in Israeli children with diarrhea and in healthy soldiers.

An ELISA test was employed to detect Campylobacter jejuni antibodies, using as antigen the glycine-HCl buffer extract of a local isolate. The antibody response (IgG, IgA and IgM) was examined in a group of 32 children (age 0-12 years) with C. jejuni enteritis diagnosed by the isolation of the agent. Controls were represented by two groups of children matched according to their age and sex: a) children with enteritis of unknown etiology, and b) healthy children. In addition, 66 healthy soldiers (aged 18-19), from whom serum specimens were collected during the first year of military service, were tested. The results indicated that the serodiagnosis of C. jejuni infection by ELISA is specific and sensitive regarding each Ig tested. The test for IgG was the most sensitive (72%) and that for IgM the most specific (100%). The healthy young adult soldiers showed significantly higher mean levels of IgG and IgA antibodies than the healthy children, suggesting that in Israel exposure to C. jejuni commonly occurs during early childhood. The ELISA for C. jejuni can improve the diagnosis of campylobacteriosis for clinical and epidemiological purposes.

Adult↗
PubMed1989

[Serologic diagnosis and therapeutic possibilities in habitual abortion].

Immunological laboratory investigations and success in the therapy of habitual abortion have led to a new view of the disease. Though we are currently unable to fully understand the underlying mechanisms, it seems to be generally accepted that insufficient production of HLA antibodies at an early stage of gestation is pathogenetically involved. Employing sensitive methods (IPI = immune phagocytosis inhibition assay) antibodies directed against fetal (paternal) histocompatibility antigens can be detected in the sera of healthy women already in the fifth week of gestation. The lack of such antibodies in the sera of aborting women is therefore an important diagnostic criterion. Strikingly good histocompatibility between the partners in couples with habitual abortion is occasionally encountered, providing an explanation for the lack of immune response in these cases. Patients with a classical clinical picture can be treated by immunization with the partner's leucocytes. The rate of success for subsequent pregnancies is about 80%. A positive effect was also observed in patients with primary infertility (about 20%).

Abortion, Habitual↗
PubMed1989

Fenfluramine administered systemically or locally increases extracellular serotonin in the lateral hypothalamus as measured by microdialysis.

Microdialysis was used to monitor serotonin, 5-hydroxyindoleacetic acid (5-HIAA) and the metabolites of dopamine, dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the perifornical lateral hypothalamus (PFH) of freely moving rats. Systemically administered d-fenfluramine (d-FEN) increased extracellular serotonin, DOPAC and HVA, while decreasing serotonin's metabolite 5-HIAA. Local application of d-FEN directly to the hypothalamic terminal region caused large increases in extracellular serotonin and had a tendency to decrease all 3 metabolites. This effect was confirmed when d-FEN was infused locally by reverse dialysis. These results provide direct evidence that the anorectic drug d-FEN can increase extracellular serotonin in the hypothalamus in vivo and suggest a serotonergic action in the perifornical region. This finding is consistent with our report that a meal also increases serotonin in this region.

Animals↗
PubMed1989

Proliferation of highly purified T cells in response to signaling via surface receptors requires cell-cell contact.

Lymphocyte proliferation is associated with cell-cell aggregation. In order to assess the importance of cell-cell contact in T-cell proliferation we examined the effect of disruption of cellular aggregation by anti LFA-1(4) mAb on T-cell proliferation. Monocyte-dependent T-cell proliferation induced by anti-CD3 mAb, pairs of anti-CD2 mAbs, or PHA was inhibited by anti-LFA-1 mAb. Monocyte-independent proliferation of highly purified T cells to anti-CD3 mAb plus PMA or plus IL-2 and to PHA plus IL-2 was, surprisingly, also inhibited by anti-LFA-1 mAb. Anti-LFA-1 mAb caused the partial inhibition of both low-affinity and high-affinity IL-2 receptor and the complete inhibition of IL-2 synthesis. In contrast to the above, the proliferation of highly purified T cells to PMA plus ionomycin was not inhibited by anti-LFA-1 mAb. These results suggest that optimal activation of highly purified T cells via cell surface receptors requires LFA-1-dependent cell-to-cell contact between proliferating T cells as well as between T cells and accessory cells. Such contact appears to be crucial for initiating IL-2 production and for optimal action of IL-2 through its receptor.

Adult↗
PubMed1989

Gene-controlled cytosine demethylation in the promoter region of the Ac transposable element in maize.

The transposase product of the Ac transposable element causes demethylation of the BamHI site in the promoter region of Ac. This site remains methylated in Ds9, the deletional derivative of Ac that fails to make an active transposase. In the presence of an active Ac element the BamHI site of Ds9 is demethylated. Transcription of the element is correlated with the demethylation of the promoter region. Evidence is presented that supports the model that the trans-acting protein causes site-specific demethylation by inducing a configuration change in chromatin structure making the site inaccessible to the methylase. A chromosome alteration that involves the insertion of the 4.5-kilobase Ac element results in the methylation of Pvu I target sites about 1 kilobase removed from the point of insertion.

Journal Article↗
PubMed1989

Paternal age and mental functions of progeny in man.

The effects of maternal age on the quality of offspring are well known. Those due to the father's age are less obvious, apart from the role of increasing paternal age in the onset of many dominant autosomal disorders. But an experimental model has demonstrated that, in rats, increasing paternal age, without any other anomalies, might produce a decreased learning capacity in progeny. The object of the epidemiological investigation presented here was to verify whether this effect might also occur in man. The study involved the distribution of scores obtained in psychometric tests by 18-year-old male subjects, according to their father's age at the time of their birth. This distribution indicated not only that increasing paternal age is accompanied by effects similar to those observed in animals, but also that very young paternal age was also related to these effects. Thus, the curve of such scores produced an inverted U-shape, with maximum scores obtained when the father was about thirty years of age. Maternal age did not appear to play a part in this event. These results pose the problem of identifying genetic and/or psychosocial factors which might have an impact on the quality of the conceptus.

Adolescent↗