Biomedical subjects

W Rhee

Publications and source records attributed to W Rhee.

6 recordsLinked to original sources

PubMed1999

Survival differences associated with treatment of cytomegalovirus retinitis in Maryland patients with AIDS, 1987-1994.

Differences in survival related to treatment of cytomegalovirus (CMV) retinitis in AIDS patients were studied. The medical records of adult AIDS patients who had been diagnosed with CMV retinitis in a Maryland inpatient facility between September 1987 and September 1994 were reviewed to assess determinants of survival, including treatment with ganciclovir and foscarnet, use of zidovudine, and demographic characteristics. The review was based on inpatient and outpatient medical records and computerized data from the Maryland HIV Information System. Of 212 AIDS patients with CMV retinitis, 123 (58.0%) were treated exclusively with ganciclovir, 55 (25.9%) received foscarnet only, and the remaining 34 (16.1%) received both ganciclovir and foscarnet at some point after their diagnosis for CMV retinitis. Patients who received both drugs survived significantly longer after the diagnosis than patients who received either drug by itself. The median time from diagnosis of CMV retinitis to death was 464 days for patients receiving both drugs, 225 days for ganciclovir recipients, and 202 days for foscarnet recipients. Other positive predictors of survival were male sex and use of zidovudine. Among Maryland adults with AIDS who were treated for CMV retinitis between September 1987 and September 1994, the most common treatment for the eye infection was ganciclovir. Patients receiving both ganciclovir and foscarnet survived longer than those treated with either drug alone.

AIDS-Related Opportunistic Infections↗

PubMed1998

Race and the treatment of cytomegalovirus retinitis in a cohort of patients with acquired immunodeficiency syndrome.

This historical cohort study assessed the impact of race on critical factors in the diagnosis and drug treatment of cytomegalovirus (CMV) retinitis in acquired immunodeficiency syndrome (AIDS) patients over a 7-year period. The study subjects included 194 adult patients with a history of AIDS who were treated for CMV retinitis between September 1987 and September 1994. Abstracted inpatient hospital medical records and a statewide automated AIDS database were the primary sources of data. Patients were assessed for severity of CMV retinitis at diagnosis, time from initial CMV retinitis diagnosis to first treatment, survival from diagnosis of AIDS, and initiation of drug treatment for CMV retinitis. Results indicated a significant difference in the severity of CMV retinitis at diagnosis by race. Patients diagnosed with early disease were more likely to be white, whereas patients diagnosed with severe disease were more likely to be black. There was no difference in the type of CMV retinitis treatment or patient survival time after diagnosis, nor time to treatment once diagnosed by race. These results suggest that differences in survival may not be the result of discrimination against black patients and may be due more likely to practices associated with accessing medical treatment.

AIDS-Related Opportunistic Infections↗

PubMed1998

A characterization of older AIDS patients in Maryland.

This retrospective study evaluated Maryland acquired immunodeficiency syndrome (AIDS) patients who were > or = 50 years at the time of AIDS diagnosis. All patients diagnosed between January 1987 and June 1996 who were > 50 years were included in the cohort. A total of 610 male (82.7%) and 128 female (17.3%) AIDS patients aged > or = 50 were identified. The most common mode of human immunodeficiency syndrome (HIV) transmission was male-to-male sexual contact (34.7%). Additionally, 146 (19.8%) patients contracted HIV through blood transfusions, 93 (12.1%) were infected through heterosexual contact, 134 (18.6) were infected through i.v. drug abuse, and the remaining 109 (14.8%) had unknown risk factors. Data from this preliminary study demonstrate that an alarming percentage of AIDS patients (approximately 10%) in Maryland are aged > or = 50. Sexual contact, either male-to-male or heterosexual transmission, was the route of transmission for nearly 47% of this patient population. However, few research projects, educational programs, or public health initiatives are specifically targeted to this patient population. The increasing life expectancy of AIDS patients as well as the advent of new drug treatments highlights the need for further research to investigate the diagnosis and treatment of AIDS and HIV infection among older patients.

Acquired Immunodeficiency Syndrome↗

PubMed1989

Injectable cross-linked collagen with improved flow properties.

Aqueous suspensions of glutaraldehyde cross-linked fibrillar collagen and non-cross-linked fibrillar collagen were examined by rheometry, particle size analysis, and microscopic techniques. Although cross-linked collagen suspensions were similar to non-cross-linked suspensions by microscopic and size analyses, they differed in rheometric properties. Concentric cylinder Couette flow, shear creep, uniaxial creep, and porous bed flow all revealed that cross-linked collagen was more resistant to deformation and flow than non-cross-linked collagen. These results were in agreement with in vivo dermal implantation studies, both in pig and human; i.e., compared to non-cross-linked collagen, the cross-linked formulation was more difficult to inject into tissue and did not spread uniformly, sometimes giving rise to palpable lumps or large masses evident in histological sections. When hyaluronic acid was blended with cross-linked collagen to achieve a final hyaluronate concentration of 5 mg/mL, there was a significant improvement in ease of injection into tissue. Rheometry on blends of hyaluronate and cross-linked collagen demonstrated that the blend required lower forces to achieve deformation and flow, compared to cross-linked collagen alone. Particle size analysis on the blend showed a reduction in fiber aggregate dimensions, compared to cross-linked collagen alone.

Animals↗

PubMed1988

The effects of heparin on the physicochemical properties of reconstituted collagen.

Pepsin-solubilized bovine dermal collagen was reconstituted in 0.02 M sodium phosphate (pH 7.2), concentrated to 30-40 mg/ml, and adjusted to physiological ionic strength by addition of sodium chloride. These preparations, at 4-15 degrees C, are fibrillar suspensions composed of fibrils of varying diameters and nonassociated molecules. Addition of heparin to these suspensions promoted a dose-dependent increase in average fibril diameter as measured by turbidimetry and electron microscopic analyses. These effects were relatively specific for heparin and heparin-like glycosaminoglycans. Chondroitin sulfate and hyaluronic acid had little or no effect on fibrillar diameters under these conditions, whereas dermatan sulfate had an intermediate effect on fibrillar reorganization. Differential scanning calorimetry revealed that addition of optimal concentrations of heparin generated fibrils of higher stability and that this effect was associated with the disappearance of structures of lower stability, including nonassociated molecules and thin fibrils. Light microscopic analyses of the fibrillar collagen/heparin matrix showed it to be a more open network of distinct collagen fibers than was observed with the fibrillar collagen preparation alone. Binding experiments indicated that heparin bound to fibrillar collagen in a saturable fashion with a Kd of approximately 4 X 10(-7) M. Creep experiments provided evidence that the addition of heparin to fibrillar collagen suspensions greatly reduces the gelation phenomenon that is normally observed when such suspensions are warmed to 37 degrees C. These differences in fibrillar architecture may be in part responsible for differences noted in the biological response to fibrillar collagen and fibrillar collagen/heparin implants in vivo (McPherson et al., 1988).

Animals↗

PubMed1987

Shear creep of injectable collagen biomaterials.

Shear creep experiments in a parallel-plate apparatus were carried out on two injectable forms of collagen: semidilute nonfibrillar solutions (32 and 45 mg protein/mL) and aqueous fibrillar suspensions (at 35 and 65 mg/mL). Nonfibrillar solutions were more easily deformed than fibrillar suspensions, and both materials continued to deform slowly, even at long times (up to 6 X 10(4) sec). When the creep compliance, J(t), was plotted versus t1/3, regions of linear dependence were identified, which indicated that the materials were undergoing Andrade creep. At higher stress levels, J(t) diverged from t1/3, and true viscous flow occurred. A delayed viscosity could be calculated which agreed with viscosities derived from measurements under conditions of steady shear Couette flow. The time of onset of viscous flow was identified with a specific strain for each material, suggesting yield strain behavior. An analysis of recovery curves showed that at low stress levels or for short experimental times, the Boltzmann superposition was approximately obeyed, indicating linear behavior. At high stress levels and times greater than 10(3) sec, both nonfibrillar solutions and fibrillar suspensions showed marked curvature of stress-strain curves, which indicated that the materials are nonlinear in creep.

Animals↗