Biomedical subjects

D H Schwartz

Publications and source records attributed to D H Schwartz.

7 recordsLinked to original sources

PubMed1992

Decrease in HIV provirus in peripheral blood mononuclear cells during zidovudine and human rIL-2 administration.

Quantification of human immunodeficiency virus (HIV) proviral DNA in peripheral blood mononuclear cells (PBMC) was performed in 13 HIV-seropositive asymptomatic individuals during 10-24 months by polymerase chain reaction amplification of multiple half-log dilutions of cellular DNA. At enrollment, subjects had a geometric mean titer of 100 copies of HIV provirus per 10(6) PBMC (mean +/- SD, 2 +/- 0.9 log10). In four untreated individuals there was no significant change in provirus levels during a mean period of 13.3 months. In eight patients treated with zidovudine (ZDV) and human recombinant interleukin 2 (rIL-2), HIV provirus copies declined to 13 per 10(6) cells (1.1 +/- 0.8 log10) at the end of the first course of ZDV and rIL-2 at week 20 (p less than 0.01), and to 40 per 10(6) cells (1.6 +/- 0.9 log10) after 12 months of treatment (p less than 0.04). Subsequent courses, which included 12 weeks of ZDV alone or 4 weeks of IL-2 alone, did not significantly change the already depressed provirus copy numbers. Proviral copy number also remained depressed during drug-free "washout periods" between courses. Finally, we observed a return to a geometric mean of 400 copies per 10(6) cells (2.6 +/- 0.3 log10) a mean of 7.9 months after discontinuation of therapy. Measurement of changes in HIV provirus should provide a direct marker for defining antiviral activity of drugs, biologics, and combination therapy.

DNA, Viral↗

PubMed1991

Antibody responses to Haemophilus influenzae type B vaccines in men with human immunodeficiency virus infection.

BACKGROUND: Persons with human immunodeficiency virus (HIV) infection are at increased risk for serious infections caused by Haemophilus influenzae, yet there are few data on their antibody responses to the H. influenzae type b vaccines. METHODS: We evaluated antibody responses in 248 men who were randomly assigned to receive a single dose of either the H. influenzae type b polysaccharide (PRP) vaccine or the polysaccharide-mutant diphtheria toxoid conjugate vaccine (PRP-CRM). The subjects were stratified into four groups: seronegative men (67 subjects), men with asymptomatic HIV infection (79), men with symptomatic HIV infection (47), and men with the acquired immunodeficiency syndrome (AIDS) (55). RESULTS: Before immunization, the subjects with AIDS had the lowest PRP-antibody titers; 40 percent had titers below the putative protective level (less than 0.15 micrograms per milliliter). In the seronegative subjects, those with asymptomatic HIV infection, and those with symptomatic HIV infection, the PRP-CRM vaccine led to a threefold greater increase in geometric mean antibody titers than did the PRP vaccine (P less than 0.01). However, the subjects with AIDS had a greater antibody response to the PRP vaccine. The antibody response of HIV-seropositive men to the PRP-CRM vaccine correlated significantly with the number of CD4 lymphocytes (r = 0.47, P less than 0.0001, as compared with r = -0.01 for the PRP vaccine). In these HIV-infected men, both vaccines elicited the dominant anti-PRP idiotype described previously in populations not infected with HIV. CONCLUSIONS: Immunization with the PRP-CRM conjugate vaccine early in the course of HIV infection is likely to confer protection against disease caused by H. influenzae type b.

AIDS Vaccines↗

PubMed1991

Stimulus-evoked changes in neostriatal dopamine levels in awake and anesthetized rats as measured by microdialysis.

The effect of medial forebrain bundle (MFB) stimulation on neostriatal dopamine levels was examined using in vivo microdialysis in urethane-anesthetized and awake, freely-moving rats in conjunction with single unit extracellular recordings from antidromically identified nigral dopaminergic neurons. Dialysis samples were collected during baseline periods or while stimulating the MFB with trains of 5 or 10 pulses at different frequencies within a physiologically relevant range. When the perfusion solution contained 1.2 mM Ca2+, even intense, high frequency stimulation was ineffective at producing significant elevations in neostriatal dopamine levels whereas cocaine or amphetamine reliably caused several-fold elevations in dopamine levels. When the perfusate contained 2.4 mM Ca2+, modest MFB stimulation within the range of spontaneous nigral cell firing produced large and reliable increases in dopamine levels. There was a significant correlation between the proportion of dopaminergic neurons that could be antidromically activated from the MFB and the increase in neostriatal dopamine. There was no effect of stimulus pattern on the increase in dopamine levels, and results obtained in awake, freely-moving animals did not differ from those obtained in anesthetized animals. These data provide good evidence that in vivo microdialysis is sensitive to neostriatal dopamine overflow evoked by stimulation within the normal rate of firing of nigrostriatal neurons and that Ringer's Ca2+ concentration is a critical variable in the detection of stimulus-induced release of dopamine.

Anesthesia↗

PubMed1991

Detection and quantification of human immunodeficiency virus RNA in patient serum by use of the polymerase chain reaction.

Human immunodeficiency virus (HIV) RNA was detected and quantified in the serum of HIV-seropositive individuals using the polymerase chain reaction (PCR) and a nonisotopic enzyme-linked affinity assay. Of 55 HIV-infected patients who were not receiving therapy, serum HIV RNA was detected in 9 of 19 who were asymptomatic, 11 of 16 with AIDS-related complex (ARC), and 18 of 20 with AIDS, with copy numbers ranging from 10(2) to greater than or equal to 5 x 10(4) 200 microliters of serum based on a relationship between absorbance and known copy number of gag gene RNA. Linear regression analysis demonstrated a correlation between infectious titer in 42 patient sera cocultured with donor peripheral blood mononuclear cells (PBMC) and PCR product absorbance (r = .70, P less than .01). Serum HIV RNA detected by PCR also correlated with serum p24 antigen positivity, CD4 counts less than 400/mm3, and the presence of HIV-related symptoms or disease. Quantification of infectious HIV RNA in cell-free serum by PCR may be useful as a marker for for disease progression or in monitoring antiviral therapy.

AIDS-Related Complex↗

PubMed1991

Absent or rare human immunodeficiency virus infection of bone marrow stem/progenitor cells in vivo.

An important question in human immunodeficiency virus (HIV) pathogenesis is whether HIV-infected bone marrow CD34+ stem/progenitor cells serve as a significant reservoir of virus in HIV-infected individuals. Our data indicate that infection of bone marrow stem/progenitor cells with HIV occurs rarely, if ever, in vivo. In the present study, CD34+ cells were immunomagnetically purified from the bone marrow of HIV-seropositive individuals, and purified cells or colony-forming cells of the granulocyte/macrophage lineage were analyzed for HIV proviral DNA by the polymerase chain reaction. No HIV DNA was detected in colony-forming cells of the granulocyte/macrophage lineage from HIV-positive patients. Furthermore, no virus was found in CD34(+)-enriched cells from six of seven samples from asymptomatic HIV-infected individuals and four of four samples from patients with AIDS-related complex or AIDS. Thus, infected stem cells are not a major source of persistent HIV and do not account for hematopoietic suppression. These findings have positive implications for the concept of marrow reconstitution with autologous stem cells, genetically engineered for HIV resistance, following marrow-ablative antiviral therapy.

DNA, Viral↗

PubMed1991

Safety and effects of interleukin-2 plus zidovudine in asymptomatic individuals infected with human immunodeficiency virus.

The safety of continuous i.v. interleukin-2 (IL-2) in conjunction with zidovudine (ZDV) was assessed in asymptomatic patients infected with human immunodeficiency virus. Clinical, immunologic, and viral parameters were monitored in a phase I/II trial with dose escalation and crossover arms. Daily doses of IL-2 from 1.5 to 12 x 10(6) IU/m2 were well tolerated and, in the presence of ZDV, did not induce increases in p24 antigenemia. Significant (p less than 0.05) but transient increases in CD4 cells were observed midway through infusion of IL-2 at all doses, and increases in natural and lymphokine-activated killer activity were seen at higher doses. Circulating hypodense eosinophils and soluble IL-2 receptors increased more than 10-fold. Of nine patients available for long-term follow up 13-25 months from baseline and 4-21 months after stopping IL-2, six still had improved CD4 counts (versus baseline), and the mean increase (135/mm3) for all nine patients was significant (p less than 0.05). Eight of these nine patients were negative for serum p24 at the start of therapy, and none had become p24 antigenemic at long-term follow-up.

Adult↗

PubMed1976

Societal responsibility for malpractice.

The purposes of providing just compensation to victims of medical injury and assuring high quality medical care are not served by the tort system. The tinkering with the tort system following the 1975 malpractice crisis will not ease the constantly increasing cost burden on the health care delivery system. Costs will double every three to four years. The only answer is a social insurance approach. The costs of a compensation system for medical injury regardless of fault could be met by eliminating the friction costs of the tort system, and would be helped by establishing national health insurance. The system could be initiated gradually and would be accompanied by quality assurance measures.

Attitude↗