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Biomedical subjects

J T Brown

Publications and source records attributed to J T Brown.

At least 37 records · Page 2Linked to original sources
PubMed1992

Physician-related barriers to breast cancer screening in older women.

Despite evidence that annual mammographic screening in women 50 years and older reduces mortality, surveys of physicians and patients have repeatedly demonstrated that annual screening mammography is not performed. The fundamental question addressed in this chapter is: If the assumption is made that the scientific evidence supports the use of mammography, what, then, are physician-related barriers to mammographic screening of elderly women? Using a model that classifies barriers to implementing prevention protocols into three categories (predisposing, enabling, and reinforcing factors), literature is reviewed to help identify reasons for low mammographic screening rates, especially in elderly women. This article concludes with a discussion of strategies that may help overcome barriers to mammographic screening in elderly women.

Aged↗
PubMed1991

Can physician education lower the cost of prescription drugs? A prospective, controlled trial.

OBJECTIVE: To determine whether an educational program featuring a drug cost manual can assist physicians in reducing their patients' out-of-pocket prescription drug expenses. DESIGN: Prospective controlled trial. SETTING: A general internal medicine-teaching clinic in a university hospital. PARTICIPANTS: Fifty-one medical interns. INTERVENTION: Thirty-one interns received a manual of comparative drug prices annotated with prescribing advice, two feedback reports, and weekly cost-oriented prescribing reminders. A control group concurrently participated in a manual-based educational program on cholesterol management. MEASUREMENTS: Copies of 3012 prescriptions written over 8 months were analyzed. MAIN RESULTS: Intervention group physicians prescribed less expensive drugs within classes of drugs. The change in drug price score per prescription was -0.15 (95% Cl, -0.27 to -0.04; P = 0.01). A score of 3 was assigned to the most expensive, 2 was assigned to intermediate-priced, and 1 was assigned to the least expensive drug or drugs in the class. An increase of 0.74 months' (Cl, 0.49 to 0.98; P less than 0.001) supply of medication was dispensed per prescription, reducing dispensing fees. The program was well accepted by the physicians. CONCLUSION: This relatively simple educational intervention can help physicians to reduce their patients' drug expenses and may serve as a model for incorporating cost information into the routine practice of medicine.

Cost Control↗
PubMed1991

The Duke Minority Medical Student Summer Fellowship: one program's attempt to attract minority residents.

Despite numerous Federal and private funding programs aimed at increasing the numbers of underrepresented minorities in medicine, the participation of minority groups in the medical profession remains low and shows little sign of improvement. With the goal of improving minority representation in our primary care residency program, the Minority Medical Student Summer Fellowship started in July 1990. The program's purpose is to give minority medical students positive exposure to primary care and attract them back for residency training. In this four-week elective, students participate in seminars with our primary care residents, see patients in a variety of clinics, and complete a project. Key implementation issues include support of the medicine chairman and dean, funding, and malpractice coverage for the students. Program evaluation from the first two students rated the clinic experiences higher than the seminar sessions and the independent project. Both students stated our fellowship made them more likely to train at this medical center should they enter a primary care program. Implications for other programs are listed.

Internship and Residency↗
PubMed1991

Breast cancer screening in older women: practices and barriers reported by primary care physicians.

Annual mammography, in combination with clinical breast examinations, can reduce mortality from breast cancer. However, surveys of both patients and physicians suggest that mammography is underutilized. This study examined whether physicians' reported breast cancer screening practices and barriers to mammography varied with patients' age. Data from 576 primary care physicians (internal medicine, family/general practice, and obstetrics/gynecology) who participated in a mailed statewide survey were analyzed. Physicians reported screening elderly women significantly less often than younger women, regardless of family history of breast cancer. With the exception of medical specialty, physicians' demographic and practice characteristics were not associated with reported screening practices. However, physicians' knowledge and beliefs about breast cancer in older women were associated with reported screening practices. When analyzing barriers to ordering mammography, cost to the patient was viewed as a barrier for women of all ages, and pain was viewed as a greater barrier for younger women; otherwise, physicians consistently believed that their elderly patients faced considerably more barriers compared with younger women. Further investigation is required to examine why primary care physicians report age-related differences in both breast screening and barriers to mammography.

Aged↗
PubMed1990

Conditional hyporecombination mutants of three REC genes of Saccharomyces cerevisiae.

We have isolated and characterized three conditional hyporecombination mutants, rec1-1, rec3-1 and rec4-1, that define three REC genes of Saccharomyces cerevisiae required for spontaneous general mitotic interchromosomal recombination. Each MATa/MAT alpha rec/rec diploid is deficient in mitotic single site gene conversion, intragenic recombination, intergenic recombination and sporulation at the restrictive temperature (36 degrees C). The rec1-1 mutation also confers conditional enhanced sensitivity to the killing effects of X-rays. The rec1-1 and rec3-1 mutations have been mapped to chromosome VII. The rec1-1, rec3-1 and rec4-1 mutations exhibit complementation at 36 degrees C for both mitotic recombination and sporulation.

Chromosome Mapping↗
PubMed1990

Genetic suppression demonstrates interaction of TonB protein with outer membrane transport proteins in Escherichia coli.

Energy-coupled reactions of the Escherichia coli outer membrane transport proteins BtuB and Cir require the tonB product. Some point mutations in a region of btuB and cir that is highly conserved in TonB-dependent transport proteins led to loss of TonB-coupled uptake of vitamin B12 and colicin Ia, whereas binding was unaffected. Most other point mutations in this region had no detectable effect on transport activity. Mutations in tonB that suppressed the transport defect phenotype of these btuB mutations were isolated. All carried changes of glutamine 165 to leucine, lysine, or proline. The various tonB mutations differed markedly in their suppression activities on different btuB or cir mutations. This allele specificity of suppression indicates that TonB interacts directly with the outer membrane transport proteins in a manner that recognizes the local conformation but not specific side chains within this conserved region. An effect of the context of the remainder of the protein was seen, since the same substitution (valine 10----glycine) in btuB and cir responded differently to the suppressors. This finding supports the proposal that TonB interacts with more of the transport proteins than the first conserved domain alone.

Alleles↗
PubMed1989

Functional outcome following spinal cord injury. A comparison of specialized spinal cord injury center vs general hospital short-term care.

The functional outcomes of 185 patients with spinal cord injuries undergoing rehabilitation who were initially treated in a specialized short-term care unit (center patients) were compared with those of 153 patients initially treated in general hospitals (noncenter patients). After stabilization, all patients were admitted to the Rehabilitation Institute of Chicago (Ill) and received the same rehabilitation program. The groups were comparable in terms of demographic, injury, and medical characteristics at the time of rehabilitation center admission, but the duration from injury to rehabilitation was more than twice as long for noncenter patients. While center patients were discharged from the rehabilitation center at equivalent functional skill levels, their daily rate of functional gains during the rehabilitation center stay was significantly greater than that of noncenter patients although the length of stay at the rehabilitation center was comparable for the two groups. These results support the practice of specialized short-term spinal cord injury care as a means of enhancing rehabilitation outcome.

Activities of Daily Living↗
PubMed1989

Photosensitization of human glioma cells by chalcogenapyrylium dyes.

Chalcogenapyrylium (CP) dyes which are specifically activated by red and near infrared light (600-900 nm) were examined as potential photosensitizers for photochemotherapy of malignant gliomas. Eleven CP dyes of varying chemical structure and redox potential were evaluated for selective toxicity against glioma and normal skin fibroblast cell cultures both before and after light activation. Eight of eleven CP dyes exhibited differential toxicity to tumor over fibroblast cells at dye concentrations of 1.0 microM. Dose dependent toxicity was seen both in the dark and after laser light activation. The toxicity of two of the CP dyes was significantly enhanced by photoactivation with 800 nm light. The CP dyes that absorb light maximally between 775 and 850 nm, in the range of excellent light penetration through brain, appear to be promising candidates as photosensitizers for treating malignant brain tumors.

Antineoplastic Agents↗
PubMed1989

The effect of a chalcogenapyrylium dye with and without photolysis on mitochondrial function in normal and tumor cells.

A chalcogenapyrylium dye 8b, which is under investigation for the photodynamic therapy of malignant gliomas (brain tumors), was evaluated for inhibition of mitochondrial function both before and after exposure to laser light of 800 nm. Neoplastic and normal cells forced to use mitochondrial substrates were killed by the light-activation of intracellular 8b as well as exposure to classic mitochondrial inhibitors, rotenone and sodium azide. Correspondingly, cells in glucose-rich media showed little decrease in viability due to the photolysis of intracellular 8b or the presence of mitochondrial toxins. The toxicity of 8b without light activation was found to be the same regardless of the cell's energy source. Measurement of cellular ATP generated during treatment also showed the photolysis of intracellular 8b to be more inhibitory towards mitochondrial function than the unactivated parent compound. We conclude that the chalcogenapyrylium dyes localize to the mitochondrion and that photoactivation results in mitochondrial injury.

Adenosine Triphosphate↗
PubMed1988

Impact of a medical journal club on house-staff reading habits, knowledge, and critical appraisal skills. A randomized control trial.

The journal club is an established teaching modality in many house-staff training programs. To determine if a journal club improves house-staff reading habits, knowledge of epidemiology and biostatistics, and critical appraisal skills, we randomized 44 medical interns to receive either a journal club or a control seminar series. A test instrument developed by the Delphi method was administered before and after the interventions (mean, five journal club sessions). By self-report, 86% of the house staff in the journal club group improved their reading habits vs 0% in the control group. Knowledge scores increased more in the journal club group than in the control group, and a trend was found toward more knowledge gained as more sessions were attended. Ability to appraise critically a test article increased slightly in each group, but there was no significant difference between the groups. We conclude that a journal club is a powerful motivator of critical house-staff reading behavior and can help teach epidemiology and biostatistics to physicians-in-training.

Biometry↗
PubMed1987

Differential retention of rhodamine 123 by avian sarcoma virus-induced glioma and normal brain tissue of the rat in vivo.

The time course of uptake, retention and clearance of the cationic lipophilic dye, rhodamine 123 (Rh123), within the central nervous system was qualitatively evaluated in rats. Weanling rats were injected intracerebrally with avian sarcoma virus, which induced malignant gliomas in situ before injection of Rh123. Comparison was made of the amount of fluorescence of Rh123 within the normal cerebral cortex, myelinated tracts of the brain, meninges, choroid plexus, and neoplastic foci at 1, 4, 8, 12 and 24 hours after intravenous injection. Fluorescence microscopy was utilized to identify tissues containing the dye. Normal neuropil did not contain Rh123 at any of the time periods studied. Gliomas retained the dye at 1, 4, 8 and 12 hours, with increasing uniformity of distribution and decreasing intensity of fluorescence over this time period. Fluorescence was not detected at 24 hours within the neoplastic tissues, but was evident at all time periods studied within the choroid plexus. The specific retention of Rh123 by malignant glioma and by the choroid plexus in vivo suggests that Rh123 may be useful for photochemotherapeutic treatment of brain neoplasms and disorders of the choroid plexus.

Animals↗
PubMed1987

Hyperthermia from interstitial laser irradiation in normal rat brain.

This study examined both the effect of variations in optical fiber tip and in light wavelength on laser-induced hyperthermia in rat brain. Normal rat brains were exposed to argon laser light (454-514.5 nm) delivered through an intracerebral end-emitting (bare-tipped) or a diffusion-emitting (sapphire-tipped) optical fiber probe. Interstitial thermistor probes recorded temperatures after thermal equilibration at varying distances from the emitting source. The end-emitting fiber produced significantly (P less than 0.05) higher elevations in tissue temperature than the diffusion-emitting fiber at the same laser power output. This is due to the smaller surface area (1.2 mm2 versus 7.8 mm2) of the end-emitting fiber, which results in a greater rate of energy delivery to tissue adjacent to the fiber tip. Changes in intracerebral temperature measurements were also recorded at similar distances from a diffusion-emitting fiber at a continuous total laser power output of 150 mW for light wavelengths of 454-514.5 nm, 700 nm, and 750 nm and at a total laser output of 1.1 W for 1,060 nm. Variations in brain tissue temperature with distance from the laser emission source were compared for each laser group with the tissue temperature profile generated by a radiofrequency (wavelength 600-625 m) interstitial probe. Similar temperature changes were found for all visible wavelengths near the probe, suggesting that the thermal response of brain adjacent to an interstitial laser fiber is primarily dependent upon the rate of energy delivery and not upon wavelength. The thermal profile versus distance from the light source depends mostly upon the level of temperature rise near the interstitial laser fiber tip and not the wavelength of laser light used. These results have important implications in interstitial applications of laser for hyperthermia and photochemotherapy.

Animals↗
PubMed1987

Cloning and characterization of tetM gene from a Ureaplasma urealyticum strain.

We have cloned a 4.9-kilobase (kb) HincII fragment which contains a tetracycline resistance determinant (tetM) from the chromosome of Ureaplasma urealyticum. The 4.9-kb HincII fragment contains DNA in addition to the structural gene, is closely related to the previously characterized 5.0-kb fragment from pJI3, and contains no normal ureaplasmal DNA sequences.

Cloning, Molecular↗
PubMed1987

Interstitial laser photochemotherapy of rhodamine-123-sensitized rat glioma.

The effect of interstitial laser photochemotherapy with the mitochondrial-specific intravital dye rhodamine-123 (Rh-123) was studied using a malignant rat glioma model system (RT2). Tumors were transplanted subcutaneously into the flank of athymic mice and into the cerebrum of adult rats. The Rh-123 photosensitization was produced by direct intratumoral injection of Rh-123 into the mouse RT2 flank tumors and by intravenous Rh-123 administration to adult rats with implanted RT2 intracerebral tumors. Intratumoral irradiation with 150 mW of argon laser light for an exposure time of 15 minutes was performed using a conical sapphire-tipped quartz optical fiber. Control groups of animals received either no treatment, Rh-123 injections, or administration of 150 mW of argon laser light for 15 minutes. Both flank and intracerebral tumors showed progressive diminution in size after treatment with Rh-123 photochemotherapy. There was no evidence of tumor recurrence in 60% of Rh-123 photochemotherapy-treated tumors. Recurrences in tumors treated with Rh-123 photochemotherapy usually appeared at the periphery of the original tumor at 10 days after treatment. Histologically, photochemotherapy-treated intracerebral tumors showed progressive shrinkage with increasing tumor necrosis over time. The finding of residual or recurrent tumor at the periphery of the original tumor mass suggests that the lack of penetration of the blue-green (argon) light was responsible for preventing complete tumor ablation. Our results suggest that Rh-123 photochemotherapy can destroy malignant gliomas in vivo; however, the poor penetrability of the photoactivating blue-green light may limit the effectiveness of this treatment for large or extensively invasive tumors.

Animals↗