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Biomedical subjects

A Back

Publications and source records attributed to A Back.

At least 37 records · Page 2Linked to original sources
PubMed1993

CCLRU standards for success of daily and extended wear contact lenses.

Success in contact lens wear is often judged on the basis of patient "survival" rather than the achievement of satisfactory performance based on specific criteria. In 1971, Sarver and Harris defined a series of standards for successful polymethyl methacrylate (PMMA) lens wear which incorporated criteria for wearing time, comfort, vision, ocular tissue changes, and patient appearance. In this paper we propose a revision of these criteria based on current understanding of the ocular response to contact lens wear. These revised CCLRU (Cornea and Contact Lens Research Unit) standards for success are intended as realistic performance objectives, and can be applied in clinical trials to evaluate and compare the clinical performance of present and future rigid and soft contact lenses, worn for daily and extended wear.

Contact Lenses↗
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↗
PubMedDate not supplied

Treatment of chancroid with erythromycin.

Chancroid is a sexually transmitted disease that is not often recognized in the United States. It has traditionally been treated with sulfonamides and/or tetracyclines. Recently, 14 active-duty U. S. Army personnel who acquired chancroid in the Far East were seen at the Madigan Army Medical Center, Tacoma, Wash. All of the organisms were isolated from clinical material on solid media without the use of a blood-clot tube. Because of dissatisfaction with conventional treatment and the demonstration of in vitro sensitivity of the organism to erythromycin, seven of the last eight patients were treated with erythromycin. All patients treated with erythromycin had rapid and favorable responses and none suffered recurrences. The results of this study led to three conclusions: chancroid is a relatively common disease in the Far East, the causative organism can be isolated by most clinical microbiology laboratories with proper technique, and erythromycin is an effective drug in the treatment of chancroid.

Adult↗
PubMedDate not supplied

Development, characterization, and preliminary evaluation of a temperature-sensitive mutant of Ornithobacterium rhinotracheale for potential use as a live vaccine in turkeys.

A temperature-sensitive (Ts) mutant strain of Ornithobacterium rhinotracheale (ORT) was developed after exposure of the wild-type organism to N-methyl-N'-nitro-N-nitrosoguanidine. The Ts mutant strain grew at 31 C but had its growth inhibited at 41 C unlike wild-type parent strain. The Ts mutant and parent strains were characterized. Morphologic and biochemical properties of wild-type and mutant strains did not show any differences. The strains were also characterized by polymerase chain reaction (PCR)-based fingerprinting methods. Results showed similar patterns in repetitive sequences by repetitive PCR (enterobacterial repetitive intergenic consensus, highly conserved repeated DNA elements present in Streptococcus pneumoniae (BOX), repetitive extragenic palindromic, and Salmonella enteritidis repetitive element primers); however, random amplified polymorphic DNA fingerprinting was able to differentiate mutant and parent strains showing a unique pattern for each of the ORT strains. The rationale for the use of a Ts strain as a vaccine is based on the ability of the mutant to colonize the upper respiratory tract but not the lower respiratory tract and systemic system of the birds, where the wild-type strain causes severe lesions. In a preliminary evaluation, Ts strain of ORT was recovered from tracheas and choanae of Ts-treated turkeys for 13 days postadministration of the strain either in drinking water or by oculonasal instillation. Humoral immune response was detected in Ts-vaccinated but not in control group birds after 3 wk postadministration. Results suggest that Ts strain of ORT has promising potential use as a live vaccine for ORT.

Animals↗
PubMedDate not supplied

Susceptibility of broiler chicks to infection by avian pneumovirus of turkey origin.

In this paper we present the results of studies on the infectivity of an isolate of avian pneumovirus (APV) from turkeys to broiler chickens. Two-week-old broiler chicks free of antibodies to APV were exposed either by oculonasal or oral route with a cell cultured APV of turkey origin. Chickens from both APV-inoculated groups exhibited clinical signs that included coughing, sneezing, nasal discharge, and watery eyes during 2-8 days postinoculation. Tissue samples from birds in the APV-inoculated group were positive for APV by polymerase chain reaction (PCR) up to 9 days postinoculation. Samples of blood from both oculonasally and orally infected chickens were positive for APV. Intestinal samples from chickens infected with APV orally were positive for the presence of APV on PCR up to 9 days postinoculation. APV was reisolated from samples taken from chickens in both groups inoculated orally and oculonasally. Sera from birds exposed by the oculonasal or by the oral route showed the presence of APV-specific antibodies.

Animals↗
PubMedDate not supplied

Outer membrane proteins for serologic detection of Ornithobacterium rhinotracheale infection in turkeys.

Ornithobacterium rhinotracheale (ORT) is a bacterium responsible for a respiratory disease in turkeys and chickens and has been identified as one of the emerging respiratory bacterial pathogens. The clinical signs and lesions caused by ORT are very similar to those caused by other respiratory infectious agents; therefore, an accurate diagnostic test is necessary to identify the infection. In this study, we have investigated the use of outer membrane proteins of ORT in an indirect enzyme-linked immunosorbent assay (ELISA) to detect the exposure to ORT infection. Outer membrane proteins of ORT were extracted and used as an antigen in ELISA to detect infection in turkeys exposed to different serotypes of ORT. The ELISA results were compared with the conventional serum plate agglutination test. The agglutination test detected specific antibodies for ORT in 65% of experimentally infected turkeys during the first 2 wk of infection. The ELISA detected up to 100% of infected birds for 8 wk postinfection. The results suggest that ELISA is able to detect the exposure to ORT in later stages of the infection and this assay can be used in serologic surveillance of ORT infection for poultry in the field.

Animals↗
PubMedDate not supplied

An atypical fowl pox outbreak in broilers in southern Brazil.

An unusual fowl pox outbreak occurred in two integrated broiler operations. The uncommon characteristic of this outbreak was that the pox lesions were manifested in the feathered parts of the body, mainly in the posterior dorsal area and external part of the thigh. Diagnosis was made by means of histopathology and virus isolation. Severe losses were incurred at the processing plant as a consequence of condemnation due to dermatitis. Vaccination of day-old chicks with mild fowl pox vaccine combined with Marek's disease (HVT) vaccine in the area of the outbreak appeared to be important in controlling the disease.

Animals↗
PubMedDate not supplied

Ornithobacterium rhinotracheale infection in turkeys: experimental reproduction of the disease.

This report details the first experimental production of clinical disease, mortality, and pathology resembling that of field infections by using Ornithobacterium rhinotracheale alone. Twenty-two-week-old male turkeys were exposed to O. rhinotracheale or lung homogenate from O. rhinotracheale-infected turkeys. Within 24 hr after inoculation, turkeys given O. rhinotracheale or lung homogenate intratracheally were depressed and coughing and had decreased feed intake. By 48 hr, several birds were coughing blood and ultimately died. Grossly, the lungs were reddened, wet, and heavy, failed to collapse, and were covered by tenacious tan-to-white exudate. Microscopically, the parabronchi and air capillaries were filled with fibrin, heterophils, macrophages, and small numbers of gram-negative bacteria. The pleura was often covered by a thick layer of fibrin, heterophils, and macrophages. Turkeys that survived to day 7 postinoculation had severe, subacute pneumonia. Ornithobacterium rhinotracheale was recovered from the lungs of most birds with pneumonia and was also cultured from the air sacs, sinuses, tracheas, spleens, and livers. All turkeys inoculated with O. rhinotracheale developed antibodies to O. rhinotracheale detectable by the serum plate agglutination test.

Animals↗