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Biomedical subjects

R L Cohen

Publications and source records attributed to R L Cohen.

At least 73 records · Page 4Linked to original sources
PubMed1987

Knowledge about AIDS and high-risk behavior among intravenous drug users in New York City.

Two hundred and sixty-one intravenous (IV) drug users, distributed between a methadone maintenance program and a large detention facility in New York City, were interviewed about knowledge of AIDS, needle use practices, and risk-reduction efforts. Ninety-seven per cent of subjects recognized needle-sharing as an AIDS risk factor; subjects showed less awareness about the effectiveness of certain risk-reduction techniques and tended to over-estimate the risk of casual contact. Of those still sharing needles at the time of first becoming aware of AIDS, 63% reported having subsequently either stopped needle-sharing or ceased IV drug use entirely. Logistic regression analysis indicated that continued needle-sharing behavior was associated with the detention facility site and lower scores on an AIDS knowledge questionnaire; reduced needle-sharing was more evident among methadone program patients and among subjects with greater knowledge about AIDS. The most common reasons for continued needle-sharing among those who continued to share needles despite knowledge of risk were: 'need to inject drugs, with no clean needle available' and 'only share with close friend or relative', offered by 46 and 45% of subjects, respectively. Results suggest that certain subgroups of IV drug users have adopted risk-reduction measures in response to AIDS. Expanded educational programs, increased drug treatment capacity, and additional strategies addressing drug users' access to sterile injection equipment and the social context of needle-sharing may be necessary to curb the further spread of AIDS among IV drug users.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Thy-1+ epidermal cells are not demonstrable in rat and human skin.

Recent studies have revealed the presence of a population of Thy-1+ epidermal cells in murine epidermis. These experiments were designed to determine whether analogous Thy-1+ cell populations occur in rat and human epidermis. Thy-1+ cells could not be demonstrated in epidermal sheets derived from rat and human skin or in epidermal cell lines, KB and A431. To date, Thy-1+ epidermal cells have been observed only in murine epithelia. The cellular equivalent of the murine Thy-1+ cell in other species remains elusive.

Adult↗
PubMed1986

Prophylaxis with cefamandole nafate in elective orthopedic surgery.

A prospective, randomized, double-blind study was conducted to determine the efficacy of cefamandole nafate in reducing infections in general orthopedic procedures. Of 743 patients initially entered into the study, 715 (362 on cefamandole, 353 on placebo) fulfilled the requirements of the protocol. The infection rate was 1.6% for the cefamandole-treated group and 4.2% for the placebo group. In operations lasting longer than two hours, there were two infections in the cefamandole group and seven infections in the placebo group (p less than 0.05). Staphylococcus aureus and gram-negative bacilli were the common pathogens. Adverse side effects were limited to transient elevations in liver enzymes.

Adult↗
PubMed1985

Failure of the urinalysis and quantitative urine culture in diagnosing symptomatic urinary tract infections in patients with long-term urinary catheters.

Since urine culture and urinalysis are both of uncertain reliability in diagnosing symptomatic urinary tract infections in patients with chronic urinary catheters, we performed sequential quantitative cultures and urinalyses on 177 urine specimens from 14 patients with long-term urinary catheters during a 12-month period. We found high concentrations of greater than or equal to 2 species of aerobic bacteria or fungi in most specimens examined. Pyuria was common even during asymptomatic periods; hematuria was less common. During symptomatic urinary tract infections, neither urinalyses nor quantitative urine cultures exhibited changes specific for such infections. Thus neither urinalysis nor urine culture appears to be a reliable test for symptomatic urinary tract infections in patients with chronic urinary catheters.

Adult↗
PubMed1984

Direct effects of minoxidil on epidermal cells in culture.

Minoxidil, a potent antihypertensive agent, induces generalized hypertrichosis when administered systemically, or localized hair regrowth when applied topically to sites of severe alopecia areata. The pharmacologic mechanisms by which minoxidil stimulates hair growth are unknown. This study was designed to examine whether minoxidil has direct effects on neonatal murine epidermal cells in culture. In the presence of minoxidil, cultures showed a marked dose-dependent second peak of DNA synthesis 8-10 days after culture initiation. In addition, two morphologically distinct cell types appeared. Indirect immunofluorescence staining with keratin-specific antibody revealed cytoplasmic keratin fibers, suggesting the epidermal origin of these cells. Our experiments demonstrate that minoxidil can affect epidermal cells in culture by altering their growth pattern and phenotypic appearance.

Animals↗
PubMed1984

Dynamics of Langerhans cells in genetically defined murine epidermal cell culture.

Unlike keratinocytes, Langerhans cells express both surface ATPase activity and Ia (HLA-DR) antigens. A well-characterized in vitro system containing Langerhans cells would be of great use in elucidating their functions. Thus, epidermal cell cultures derived from neonatal Balb/c mice were examined for the presence of Langerhans cells. Twenty-four hours after initiation of culture, ATPase- and Ia-positive cells were seen to be associated with cell aggregates. By day 3, Langerhans cells migrated on to the substratum and, as the cultures matured and stratified, were seen both in groups and as single cells for the duration of the cultures (day 14). During culture, although the total number of cells increased, the percentage of cells expressing Ia antigen and ATPase activity remained constant, suggesting that Langerhans cells increase in number during cell culture. Such a situation could arise from actual division of Langerhans cells during culture or from latent expression of Ia antigen and ATPase activity by pre-existing cells. This is the first study of the dynamics of Langerhans cells in a cell culture system and shows that Langerhans cells are present throughout the lifespan of the cultures.

Adenosine Triphosphatases↗
PubMed1984

Clinical perspectives on premature tooth eruption and cyst formation in neonates.

Premature eruption of teeth occurs in 1 of every 2,000 births. The reported association between natal teeth and serious, rare, inherited syndromes suggests that particular caution should be exercised in examination of newborns having prematurely erupted teeth. The ectomesenchyma, from which the orofacial structures develop, undergoes a complex, coordinated series of steps of proliferation and differentiation during the first two months in utero. At approximately seven weeks the presumptive mandibular and maxillary arches show a bandlike ectodermal thickening called the dental lamina. Odontogenesis (tooth development) begins with budding of the dental lamina and continues into the second week of life. Remnants of odontogenic epithelium or of epithelium covering the embryonic facial processes may develop into cystic structures, causing intraoral swellings on the alveolar ridges or palate (i.e., Bohn's nodules and Epstein's pearls). Prematurely erupted natal and neonatal teeth are generally normal deciduous incisors. Hypermobility of these teeth, resulting from poorly formed roots, may stabilize within a short period of time. Extraction of natal and neonatal teeth should not be done precipitously.

Animals↗
PubMed1984

Aspartate aminotransferase increases in crevicular fluid during experimental periodontitis in beagle dogs.

A ligature-induced periodontitis model employing the beagle dog was used to study the levels of aspartate aminotransferase (AST) in crevicular fluid before and after ligation. A significant increase in AST level occurred in crevicular fluid 2 weeks after ligation whereas no increase of enzyme was found in serum. Enzyme levels in crevicular fluid were 10- to 100-fold higher than in serum. Dental plaque did not appear to be the source of the enzyme. Since aspartate aminotransferase has been documented as a marker of cellular injury arising during heart disease and liver disease, this study suggests that aspartate aminotransferase, in like fashion, reflects cellular damage arising from active periodontal disease.

Animals↗
PubMed1984

Alopecia areata treated with topical minoxidil.

A 1% minoxidil topical solution was used to treat 48 patients with alopecia areata, ie, 24 patients with patchy disease and 24 patients with alopecia totalis or alopecia universalis. Twenty-five patients had terminal hair regrowth; in 11 of the 25 patients, it was cosmetically acceptable. No clinical features of the disease seemed to indicate the likelihood of hair regrowth. Hair regrowth began approximately two months after the initiation of treatment and was not uniformly well maintained after the treatment was terminated. One patient had an allergic contact dermatitis reaction to the minoxidil solution; no systemic side effects were seen. No notable systemic absorption was found in 18 adult patients. Effects on cutaneous blood flow or the immune system or some direct effect on hair follicles are possible mechanisms by which minoxidil therapy might stimulate hair growth.

Administration, Topical↗