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Biomedical subjects

A Back

Publications and source records attributed to A Back.

10 recordsLinked to original sources
PubMed1992

Chlamydia trachomatis infection in women: a need for universal screening in high prevalence populations?

Chlamydia trachomatis is the most prevalent sexually transmitted bacterial pathogen. Nevertheless, selective, rather than universal, screening for chlamydia has been recommended, largely because testing is expensive and requires considerable technical expertise. A total of 1,348 women in four family planning clinics in San Francisco, California, were screened from March 1987 to January 1988 to identify criteria for selective screening. Of these, 9.2% had a positive chlamydia test using direct fluorescence. Logistic regression analysis identified five factors associated with infection: age less than 25 years, cervical friability, single marital status, a new sexual partner within the past 3 months, and lack of barrier contraceptive use. No single risk factor or combination of risk factors had both a high sensitivity and a high positive predictive value for infection. While screening all women who were unmarried would detect 93% of those with chlamydia, the positive predictive value of 10.7% was not much higher than the overall prevalence. Conversely, screening all women with cervical friability, which had a positive predictive value of 23.2%, would only detect 11% of those with chlamydia. On the basis of the authors' findings, selective screening should not be used in high prevalence populations in which all women are at risk and should be screened for chlamydia.

Adolescent↗
PubMed1992

Comparative visual performance of three presbyopic contact lens corrections.

We compared the visual performance of a soft diffractive (DIFF) bifocal contact lens, a near center (CN) concentric bifocal design, and monovision (MV), using a comprehensive vision testing protocol. Fifteen presbyopic subjects who were successfully wearing DIFF bifocal contact lenses participated in the study. Of the three systems tested, MV provided best visual acuity at distance and near; less than one line of acuity was lost relative to best spectacle acuity under all lighting and contrast conditions, and there was less disturbance of a point source of light. Both bifocal corrections gave similar visual acuity performance, with more lines of acuity lost relative to spectacles at near compared to distance. However, the concentric bifocal induced more ghosting at near than the other two systems. Stereopsis was compromised at distance with MV correction, but all systems performed worse than spectacles at near. An understanding of the strengths and weaknesses of presbyopic contact lens options allows the clinician to improve management of the presbyope who wishes to wear contact lenses.

Contact Lenses, Hydrophilic↗
PubMed1992

Twelve-month success rates with a hydrogel diffractive bifocal contact lens.

In this study we assessed success rates over 12 months with a hydrogel diffractive bifocal contact lens. A total of 108 presbyopes were fitted with lenses, and after 12 months 46% were still wearing the lenses. Subjects with previous presbyopic lens-wearing experience achieved greater success (58% of those fitted) than neophyte lens wearers (33% of those fitted, and 17% of all neophyte presbyopes initially expressing an interest in contact lenses before screening). More neophytes failed for nonvision-related reasons than experienced subjects (31% vs. 12% of those fitted). Consequently, when nonvision-related failures were excluded from the calculation of success rates, 59% of those fitted with lenses (49% of neophytes and 66% of experienced subjects) were still wearing the lenses at 12 months. Most discontinuations from lens wear occurred in the first month of the study, the major reason for discontinuation being poor near vision (blur and/or ghosting; 47% of discontinuations).

Aged↗
PubMed1990

Monovision.

Monovision has been a controversial contact lens correction modality for over 30 years. This paper addresses the major issues and concerns and considers them in the light of patient safety, visual efficiency and practitioner liability.

Adaptation, Ocular↗
PubMed1989

Guide to the clinical assessment of on-eye wettability of rigid gas permeable lenses.

The number of rigid gas permeable (RGP) contact lens materials is increasing rapidly. One of the most critical issues for acceptance of new materials is lens wettability. This paper describes techniques for assessing lens wetting characteristics while the lenses are worn on the eye, and relates each observation to the lens material properties or patient tear characteristics. This method of lens wetting assessment is intended to aid the practitioner in determining the optimal lens material for a patient, based upon assessment of the interactions inherent in the lens-eye system.

Blinking↗
PubMed1989

Regimen-related toxicity and early posttransplant survival in patients undergoing marrow transplantation for lymphoma.

Ninety-five patients transplanted for malignant lymphoma were retrospectively evaluated for regimen-related toxicity (RRT) and early posttransplant survival. Nineteen patients developed life-threatening (grade 3) or fatal (grade 4) RRT in one or more organs. Grade 3 or 4 RRT was more common in patients with advanced disease versus those transplanted earlier in their course (P = .008), and was more common in patients with advanced disease conditioned with cytarabine (Ara-C)/total body irradiation (TBI) versus those prepared with cyclophosphamide (CY)/TBI (P = .033). There was no significant difference in the incidence of grade 3 or 4 toxicity in autologous, histocompatibility locus antigen (HLA)-identical, or HLA-mismatched marrow recipients. Grade 3 or 4 RRT tended to be more common and 100-day survival worse in patients with a Karnofsky performance status of less than 90 (P = .063 and .0002, respectively). Patients receiving 20 Gy or more of mediastinal irradiation before coming to transplant had more idiopathic or cytomegalovirus (CMV) interstitial pneumonitis than those who received less than 20 Gy (30% v 9%, P = .027). The probability of survival decreased with the number of organs in which toxicity was observed (P = .0001). Severe or fatal toxicities directly related to the preparative regimen are a significant problem in the treatment of patients with advanced malignant lymphoma and can be reduced by carrying out transplantation earlier in the course of the disease.

Actuarial Analysis↗
PubMed1977

Patterns of sexually transmitted enteric diseases in a city.

In the past three years cases of shigellosis, amoebiasis, and viral hepatitis A and B have increased fourfold to tenfold in San Francisco. These diseases were most common in people who had adopted "alternative life-styles", especially in young men, In many cases there was a history of frequent orogenital and oral-anal sexual contact between men with no common source. Despite energetic public-health measures and intensive efforts by physicians treating these cases, the increase has not yet been brought under control. Other cities may experience similar difficulties with sexual transmission of enteric diseases.20

Adult↗