Structural impediments to operational syringe-exchange programs.
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Connecticut↗
Biomedical subjects
R Heimer
Publications and source records attributed to R Heimer.
HIV incidence among New Haven needle exchange participants: updated estimates from syringe tracking and testing data.
This article provides updated estimates of the rate of new HIV infections among participants in New Haven's legal needle exchange program from syringe tracking and testing data. We previously reported that based on data collected from November 1990 through May 1992, the maximum likelihood incidence rate was zero with a 95% confidence interval of 0-10.2 new infections per 100 drug injectors per year. Expanding this data set through August 1993, the same statistical methods yield a maximum likelihood estimate of 1.63 new infections per 100 drug injectors per year with a 95% confidence interval of 0-7.2. Given these data, the null hypothesis of no new infections cannot be rejected, providing further support for the efficacy of New Haven's needle exchange program.
Confidence Intervals↗
TGF-beta modulates the synthesis of proteoglycans by myocardial fibroblasts in culture.
In this study we examined the production of proteoglycans by fibroblasts cultured from the left ventricular myocardium of normal adult rats. Various molecular species of proteoglycan were detected, either by labeling glycosaminoglycan chains with 35SO4 or by labeling the proteoglycan core protein with [35S]methionine. The medium of the cell cultures, which contained quantitatively most of the proteoglycans, appeared to consist mainly of biglycan, lesser amounts of decorin and proteoglycans of higher molecular weight. Biglycan and decorin were identified not only by the characteristic mobility of the intact protein and the core protein but also by immunolocation on Western blots. TGF-beta upregulated the synthesis of all these proteoglycans, coincident with elongation of glycosaminoglycan side chains observed for biglycan and decorin. The apparent molecular weight of the core protein of the two proteoglycans remained unaffected by TGF-beta. The results of these experiments suggest that with regard to proteoglycan synthesis and its regulation by TGF-beta, cultured fibroblasts originating from the myocardium share to a large extent the properties of cultured fibroblasts of other organs.
Animals↗
Pyrimethamine analysis by enzyme inhibition and HPLC assays.
Pyrimethamine is an antiparasitic agent currently used for therapy of central nervous system toxoplasmosis, a disease seen with increasing frequency in association with the AIDS epidemic. Monitoring of pyrimethamine levels may be particularly important because patients may be treated with high doses of the drug for extended periods of time. The authors have developed and validated both a new enzyme inhibition assay that can be run on an automated analyzer and an improved high performance liquid chromatography (HPLC) method. The calibration range of both methods is 100 to 3,000 micrograms/L. Both demonstrate good linearity, specificity, and precision, and correlate well with one another (r = 0.99). The CVs of the enzyme inhibition assay were < or = 8.6% and those of the HPLC method were < or = 5.4%. No interference was noted for a variety of drugs likely to be used concomitantly with or in lieu of pyrimethamine with the exception of a minor interference from trimethoprim in the enzyme inhibition assay. The major advantage of the enzyme inhibition assay is its ease of automation. The major advantages of the HPLC assay are its precision and relative simplicity. These methods should facilitate therapeutic monitoring of pyrimethamine.
Calibration↗
Syringe and needle exchange to prevent HIV infection.
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HIV Infections↗
A circulation theory of needle exchange.
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Connecticut↗
A decline in HIV-infected needles returned to New Haven's needle exchange program: client shift or needle exchange?
The New Haven needle exchange program experienced a significant decline in the fraction of returned needles containing human immunodeficiency virus 1 (HIV-1) proviral DNA. Is this decline due to the operations of the needle exchange or to a shift in clients? Analysis of demographic and behavioral data revealed that only one variable, the race of participating clients, changed significantly over time. However, HIV-1 prevalences in needles given to Whites and to non-Whites were not statistically different. Thus, client shift cannot be responsible for the decline in the observed HIV prevalence in needles. Instead, needle circulation times were a significant predictor of HIV prevalence.
Connecticut↗
HIV incidence among needle exchange participants: estimates from syringe tracking and testing data.
This paper develops a statistical procedure for estimating the HIV infection rate among needle exchange clients without using any self-reported information. Instead, data are accumulated by following the distribution and return of sequentially labeled syringes and by testing a sample of returns for the presence of HIV-1 proviral DNA using polymerase chain reaction. For each drug injector in the sample, a maximum likelihood change point model is constructed to determine if a statistically significant upward shift in the fraction of needles testing HIV positive is evident, as would occur if the drug injector in question became infected. A second maximum likelihood model is formulated to estimate the HIV incidence rate among needle exchange participants by aggregating the individual change point results. When these methods are applied to the syringe tracking and testing data collected to evaluate the legal needle exchange program in New Haven, Connecticut, the maximum likelihood incidence estimate equals zero, with a 95% confidence interval of 0-10.2 new infections per 100 drug injectors per year. Given these data, we cannot reject the null hypothesis that no new infections have occurred among needle exchange participants between November 1990 and May 1992.
Connecticut↗
Needle exchange decreases the prevalence of HIV-1 proviral DNA in returned syringes in New Haven, Connecticut.
PURPOSE: To report on the deployment of the syringe tracking and testing system in the New Haven needle exchange program, which is the first federally funded evaluation of a needle exchange program conducted in the United States. PATIENTS AND METHODS: A legal needle exchange for intravenous drug users began in New Haven, Connecticut, in November 1990. All syringes distributed by the program received unique tracking codes. Syringes were tracked and HIV-1 proviral DNA prevalence in returned syringes was assessed using polymerase chain reaction and Southern blotting. RESULTS: At the outset of the program, the prevalence of HIV-1 proviral DNA in syringes exceeded two thirds. Prevalence decreased rapidly to less than 45% during the first 3 months of the program and remained at this level for the following 10 months. During the periods of decreasing prevalence and subsequent steady state, no changes in the demographics of program participants or in the drug use habits of newly enrolling clients that could account for the decrease in HIV-1 prevalence in needles were detected. In addition, the program referred almost 20% of its clients to drug treatment programs. CONCLUSION: The needle exchange program in New Haven has decreased the percentage of syringes testing positive for HIV-1 proviral DNA among needle exchange clients while simultaneously serving as an entry point for drug treatment.
Analysis of Variance↗
Glycosaminoglycans and chondroitin/dermatan sulfate proteoglycans in the myocardium of a non-human primate.
Lyophilized mid-wall left ventricular myocardial tissues of the long-tailed non-human primate, Macaca fascicularis, were examined for the presence of glycosaminoglycans and chondroitin/dermatan sulfate proteoglycans. Mean uronic acid concentration in all samples was 0.97 +/- 0.27 micrograms per mg dry weight myocardium. The distribution of the glycosaminoglycans in the myocardium, determined by cellulose acetate strip electrophoresis was 62 +/- 4% heparan sulfate, 20 +/- 6% hyaluronan, and 16 +/- 5% chondroitin/dermatan sulfate. The analysis of chondroitin/dermatan sulfate proteoglycans, done directly on the extracts of lyophilized myocardium using agarose-acrylamide gel electrophoresis and Western blotting with monoclonal antibodies to various carbohydrate epitopes and with polyclonal antibodies to the protein core, showed the presence of biglycan and decorin. That these two and no other chondroitin/dermatan sulfates were present was established by core protein analysis using SDS PAGE and Western blotting. Quantification of chondroitin/dermatan sulfate proteoglycans uncovered high individual specific variability of the chondroitin/dermatan sulfate epitopes, but only moderate variability of biglycan and decorin core proteins. The variability of the chondroitin/dermatan sulfate epitopes is most likely related to individual specific differences in chain number, iduronate content and sulfation patterns of biglycan and decorin.
Animals↗
HIV DNA and antibodies in syringes from injecting drug users: a comparison of detection techniques.
OBJECTIVE: Direct HIV testing of individual injecting drug users is not always feasible. As an alternative, we have evaluated the sensitivity and specificity of several techniques for detecting HIV-1-specific products in used syringes. DESIGN: Polymerase chain reaction (PCR) and antibody-capture assays were compared using syringes prepared with blood from HIV-1-positive and -negative individuals. METHODS: PCR sensitivity was maximized, enabling detection of single copies of HIV-1-specific proviral DNA. The limits of detection from used syringes were determined for PCR by diluting extracts and correlated to CD4+ cell counts. Similarly, limits of detection were determined for enzyme immunoassays (EIA) and Western blot. RESULTS: All techniques were highly specific, although with PCR false-positives were detected occasionally. EIA proved more sensitive than Western blot in detecting needles containing HIV-1-infected individuals' blood. Even after prolonged storage of syringes at room temperature, EIA was equal to or better than PCR as an HIV-1 detection technique. The most sensitive method for detecting HIV-1 was the viral-based EIA when the recommended predilution step was omitted. CONCLUSIONS: EIA proved preferable to PCR because of their higher sensitivity, absence of false-positives and easier sample preparation and analysis.
Blotting, Western↗
Prevalence of HIV-infected syringes during a syringe-exchange program.
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Connecticut↗
Detection by polymerase chain reaction of human immunodeficiency virus type 1 proviral DNA sequences in needles of injecting drug users.
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DNA, Viral↗
Normal human synovial fluid and articular cartilage contain similar intact proteoglycans.
This work, directed to characterization of proteoglycans present in normal human synovial fluid by Western blotting techniques, revealed an intimate relationship of these proteoglycans to those of articular cartilage. Analyses were performed on samples subjected to digestion with chondroitinase ABC, in the presence or absence of keratanase, yielding products containing core proteins with glycosaminoglycan side chain stubs. The proteoglycan core proteins contained epitopes reactive with monoclonal antibodies that distinguish between chondroitin sulfate-4 and chondroitin sulfate-6. Additionally, these products reacted with monoclonal antibody to keratan sulfate when keratanase was omitted from the digestion. The analysis of synovial fluid revealed that the proteoglycan core proteins expressed predominantly the chondroitin sulfate-6 epitope, with expression of the chondroitin sulfate-4 epitope demonstrable only in prepubertal individuals. There was coexpression of both chondroitin sulfate epitopes in all proteoglycan core proteins of prepubertal individuals. Coexpression of chondroitin sulfate and keratan sulfate epitopes occurred in all proteoglycan core proteins. Proteoglycan core proteins had M(r) similar to those obtained from articular cartilage. Hence, in individuals free of joint disease, most proteoglycans seem to be transferred from articular cartilage to the synovial fluid without major alteration in the apparent size of the proteoglycan core protein. Only a minor set of proteoglycan core proteins had no direct articular cartilage equivalent. As this set also contained keratan sulfate, it is likely to be of articular cartilage origin, but probably modified by proteolysis.
Adolescent↗
A model-based estimate of HIV infectivity via needle sharing.
Critical to understanding the spread of the human immunodeficiency virus via needle sharing among drug users is the infectivity, i.e., the conditional probability of infection given injection with a shared, contaminated syringe. A simple mathematical model was constructed that relates infectivity to the prevalence of infection in needles used by drug users, the mean shared injection frequency among drug users, the probability that a needle is disinfected prior to use, and the mean AIDS incubation time. Three of these parameters have been estimated using data from the New Haven, Connecticut legal needle exchange program. Using the polymerase chain reaction to test for the presence of HIV proviral DNA in a sample of returned needles, we determined that 67.5% were HIV positive. We were able to estimate shared injection rates and disinfection rates from surveys of drug users enrolled in the needle exchange and our syringe tracking system. Current estimates of the mean AIDS incubation time are available in the literature. Our model implies that the probability of infection per injection with a contaminated syringe equals 0.0067, which is slightly higher than the transmission probabilities of 1/300 to 1/200 estimated from needlestick studies, and a factor of 3 higher than estimates of the probability of HIV transmission per vaginal sex act from a infected man to an uninfected woman.
HIV Infections↗
RNA-directed actions of 5-fluorouridine in hemin stimulated K-562 erythroleukemia cells.
The cytotoxic actions of 5-fluorouridine (FUrd) have been evaluated in K-562 erythroleukemia cells, focussing on RNA-directed actions. FUrd was employed such that little DNA-directed cytotoxicity was seen. Substantial inhibition of cellular proliferation was observed at concentrations of FUrd which did not inhibit significantly the activity of thymidylate synthase and which were reversed by less than 10% by exogenous thymidine. In contrast, the syntheses of both poly A- and poly A+ RNAs were substantially reduced. The effects of FUrd on rRNA included reduction by greater than 90% of mature rRNA following a 2 h exposure to 1 microM FUrd, which persisted for at least 48 h, and the appearance of partially processed nuclear rRNA precursors incapable of being metabolized to mature rRNA. FUrd also decreased the levels of several mRNAs, including those for the proto-oncogenes c-myc and c-abl, and for gamma-globin, by 40 to 70%. In contrast to the effects of FUrd on rRNA, decreases in mRNA levels were reversible, and within 12 h following a 2 h exposure to 1 microM FUrd, mRNA levels for each of these three mRNAs were back to those present in untreated control cells. mRNAs did not respond in a connected fashion to FUrd. Thus, levels of beta-actin mRNA were unchanged and levels of ornithine decarboxylase mRNA were increased by exposure to FUrd. These findings demonstrate that FUrd acted in multifarious ways to alter mRNA synthesis and longevity. Inhibitors of individual RNA polymerases were used to analyze the degree to which the FUrd-induced inhibition of RNA metabolism was linked to cytotoxicity. Both actinomycin D, which specifically interfered with the incorporation of FUrd into rRNA transcripts, and alpha-amanitin, which specifically inhibited incorporation of FUrd into mRNA transcripts, decreased the cytotoxicity of FUrd, suggesting that incorporation of FUrd into both mRNA and rRNA precursors plays a role in the RNA-directed cytotoxic actions of FUrd. However, the antagonism provided by actinomycin D was greater than that produced by alpha-amanitin, demonstrating that inhibition of rRNA synthesis is the predominant mechanism of cytotoxicity in K-562 cells exposed to FUrd.
Actins↗
HIV prevalence among intravenous drug users: model-based estimates from New Haven's legal needle exchange.
The legal needle exchange in New Haven, Connecticut, was signed into law in July 1990. As part of a rigorous effort to evaluate this program, all distributed syringes receive unique tracking codes, and a sample of returned needles are tested for the presence of HIV proviral DNA via polymerase chain reaction. These data, in conjunction with "back-of-the-envelope" statistical models, allow the estimation of HIV prevalence among those intravenous drug users participating in the needle exchange. We present four new techniques for calculating prevalence estimates: the majority rule cutoff model, the random sharing model, the sharing network model, and a version of Kaplan's "needles that kill" model. To our knowledge, these estimates are the first that attempt to infer HIV prevalence among intravenous drug users via syringe tracking and testing. All four techniques suggest a prevalence of infection of approximately 60%.
Connecticut↗
Altered expression of chondroitin sulfate proteoglycan in the stroma of human colon carcinoma. Hypomethylation of PG-40 gene correlates with increased PG-40 content and mRNA levels.
The connective tissue stroma of malignant tumors is a newly formed tissue that supports the growth and progression of neoplastic cells. Proteoglycans are intrinsic components of this complex structure and molecular changes in this class of macromolecules can significantly affect behavioral properties of transformed cells. We report that human colon carcinoma contained increased levels of a chondroitin sulfate proteoglycan that exhibited an altered glycosaminoglycan structure in which 0- and 6-sulfated units, as detected by specific monoclonal antibodies, predominated. Proteoglycans with such epitopes were localized primarily to the connective tissue stroma surrounding the tumor cells but not to the tumor cells themselves or the native, non-cancerous connective tissue. Analysis of mRNA encoding PG-40, the main chondroitin sulfate proteoglycan of colon tissue, revealed a 7-fold increase in the two transcripts encoding this gene product. This increase was evident whether the data were normalized to total RNA content or beta-actin mRNA levels. The altered steady state levels of PG-40 mRNA did not correlate with any significant gene amplification or rearrangement of PG-40 in human colon cancer. However, when genomic DNA was tested for degree of methylation, the colon carcinoma tissue showed a marked hypomethylation of PG-40 gene locus, a finding that has been associated with increased gene activation. Interestingly, PG-40 gene was also hypomethylated in cultured colon fibroblasts, which express PG-40, but not in colon carcinoma cells which do not express this gene. These results indicate that specific proteoglycan changes occur in colon carcinoma and that these alterations are the product of stromal cells that are topologically associated with and functionally respondent to the growing malignant cells. This is the first evidence that enhanced PG-40 expression in a human malignant tissue is associated with a hypomethylated gene and suggests that the control of PG-40 gene expression may represent an important factor in the progression of colon carcinoma.
Actins↗