Acquired immunodeficiency syndrome in New York City. Evaluation of an active surveillance system.

In January 1983, the New York City Department of Health initiated an active surveillance program for acquired immunodeficiency syndrome (AIDS) in 19 hospitals and a modified-active surveillance program in the remaining 69 hospitals. We reviewed hospital laboratory and autopsy records in 12 active surveillance hospitals and three modified-active surveillance hospitals six months later. Patients who had opportunistic diseases characteristic of AIDS diagnosed in 1982 (before active surveillance) and 1983 (after implementation of active surveillance) were matched against health department AIDS surveillance reports. For the 16 months we evaluated, 96% of patients identified with AIDS in the 12 active surveillance hospitals and 100% of those in the three modified-active surveillance hospitals had been reported to the health department. The delay between diagnosing a case and reporting it to the health department significantly decreased between 1981 and the first six months of 1983 in all hospitals. The proportion of cases reported within one month of diagnosis increased from 45% to 69% during this period. We conclude that the current surveillance program for AIDS in New York City is effective and that case reporting is sufficiently complete for accurate analysis of disease trends.

National case-control study of Kaposi's sarcoma and Pneumocystis carinii pneumonia in homosexual men: Part 1. Epidemiologic results.

To identify risk factors for the occurrence of Kaposi's sarcoma and Pneumocystis carinii pneumonia in homosexual men, we conducted a case-control study in New York City, San Francisco, Los Angeles, and Atlanta. Fifty patients (cases) (39 with Kaposi's sarcoma, 8 with pneumocystis pneumonia, and 3 with both) and 120 matched homosexual male controls (from sexually transmitted disease clinics and private medical practices) participated in the study. The variable most strongly associated with illness was a larger number of male sex partners per year (median, 61 for patients; 27 and 25 for clinic and private practice controls, respectively). Compared with controls, cases were also more likely to have been exposed to feces during sex, have had syphilis and non-B hepatitis, have been treated for enteric parasites, and have used various illicit substances. Certain aspects of a lifestyle shared by a subgroup of the male homosexual population are associated with an increased risk of Kaposi's sarcoma and pneumocystis pneumonia.

Surface roughness and edge geometries in hemolysis with rotating disk flow.

Judging biocompatibility of materials with blood includes assessment of hemolysis resulting from flow in contact with those materials. Such hemolysis is influenced in part by the surface roughness and specific hydrodynamic features of the device used. Using a rotating-disk device, with polyethylene disks and human blood, it was shown that roughness under 4 microns has negligible effect and that hemolysis increases sharply for roughness above about 11 microns. Gross roughness (65 microns) causes qualitatively different hemolysis kinetics but not as severe hemolysis as extrapolated from low-roughness data. In the disk geometry, the corner is a key region which generates high hemolysis and thus minor alterations cause hemolytic variations which may tend to obscure materials influences. A series of corner-beveled polycarbonate disks were tested in comparison with the normal square corner and were found always to cause greater hemolysis. Tapering the bevel inward, so the taper angle was on the order of 2 degrees-4 degrees, reduced hemolysis relative to the 45 degree bevel but still was more hemolytic than the flat disk. Evidence suggests that glassy plastics can be machined with more reproducibility at the corners than plastics above their Tg such as polyethylene. General device design problems regarding hemolysis are discussed.

Hemolytic properties of special materials exposed to a shear flow, and plasma changes with shear.

Three types of materials of special interest to the NIH Biomaterials Program were evaluated for their tendency to induce hemolysis when exposed to a laminar blood flow between rotating parallel disks. The three types were: (1) TDMAC-heparinized surfaces of polycarbonate (Lexan), silicone rubber, and polyvinylchloride; (2) polyacrylamide hydrogels (PAH) prepared by three different chemical processes; and (3) fluorinated ethylcellulose (FEC). All were compared to a polyethylene (PE) standard, to normalize data for variations in blood quality. Multiple tests, showing good reproducibility, demonstrated: FEC is a very low hemolyzer, about 60% of the PE; PAH surfaces are poorer than PE, giving 120-220% of PE hemolysis depending on fabrication and shipment history; and TDMAC-heparinized surfaces are highly hemolytic, in the range 160-440% of PE depending on substrate. Plastics used as substrates for the coating cited above were also evaluated: Delrin, Lexan, Nylon 6, propylene, and a polyether urethane. Tentative explanations are advanced for hemolytic variations, in terms of surface chemistry and material interactions with the blood.