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Biomedical subjects

K L Brown

Publications and source records attributed to K L Brown.

At least 109 records · Page 6Linked to original sources
PubMed1979

Postlactational tumoral granulomatous mastitis: a localized immune phenomenon.

Recurrent, nodular necrotizing granulomatous mastitis in two patients is reported in detail. Pathologic, immunologic, and bacteriologic studies in one patient indicate that this entity is different from plasmas cell mastitis, fat necrosis, mammary ductal ectasia, and the usual infectious and puerperal mastitis. Systemic antibreast autoimmune mastitis and vasculitis are also ruled out. Its pathogenesis, differential diagnosis, surgical treatment, and prognosis are discussed.

Adult↗
PubMed1976

The acid-catalyzed decompostion of phenacylcobalamin: evidence for the formation of an enol-Co(III) pi-complex intermediate.

Phenacylcobalamin has been synthesized and characterized by thin-layer chromatography and uv-visible spectroscopy, as well as identification of the cobalt-containing and organic products of its cleavage in acid and base and by aerobic photolysis. The major organic product from all three cleavage reactions is acetophenone and the cobalt-containing product is aquacobalamin (or hydroxocobalamin, its conjugate base). In aqueous acidic solution (pH 0 to 7.3, ionic strength 1.0 M, and 25.0 degrees C), the kinetics of the formation of aquacobalamin are biphasic representing the linear sum of two exponential terms. The pH dependence of the first-order rate constant of both phases shows a first-order dependence on proton concentration but with an inflection point ot pH 3.55 for the faster phase and at pH 4.03 for the slower phase. This behavior is interpreted in terms of the specific acid catalyzed formation of an intermediate from both "base on" and "base off" phenacylcobalamin with different second-order rate constants for each form, followed by an intermediate decompotion step with a similar formal mechanism. The nature of the intermediate is discussed and it is concluded to be a pi-complex between cob(III)alamin and the enol of acetophenone.

Binding Sites↗
PubMedDate not supplied

Rare metastasis of primary bronchogenic carcinoma to sigmoid colon: report of a case.

The authors present a case of a rare metastasis of bronchogenic carcinoma to sigmoid colon. Carcinoma of the lung usually spreads locally to adjacent mediastinum or paratracheal lymph nodes via the lymphatics. When tumor invades the pulmonary vein, distal metastases are most often to brain, suprarenal glands, or bones. Primary bronchogenic carcinoma has been reported to metastasize to jejunum, maxillary antrum, small bowel, tongue, and rarely to other organs. The authors believe that metastasis to the large intestine is most exceptional. Occurrences of rare metastasis are not well understood, though one theory implicates sites of previous trauma.

Carcinoma, Bronchogenic↗
PubMedDate not supplied

Murine scrapie infection causes an abnormal germinal centre reaction in the spleen.

Follicular dendritic cells (FDCs) of the lymphoreticular system play a role in the peripheral replication of prion proteins in some transmissible spongiform encephalopathies (TSEs), including experimental murine scrapie models. Disease-specific PrP (PrPd) accumulation occurs in association with the plasmalemma and extracellular space around FDC dendrites, but no specific immunological response has yet been reported in animals affected by TSEs. In the present study, morphology (light microscopical and ultrastructural) of secondary lymphoid follicles of the spleen were examined in mice infected with the ME7 strain of scrapie and in uninfected control mice, with or without immunological stimulation with sheep red blood cells (SRBCs), at 70 days post-inoculation or at the terminal stage of disease (268 days). Scrapie infection was associated with hypertrophy of FDC dendrites, increased retention of electron-dense material at the FDC plasma membrane, and increased maturation and numbers of B lymphocytes within secondary follicles. FDC hypertrophy was particularly conspicuous in immune-stimulated ME7-infected mice. The electron-dense material was associated with PrP Napoli accumulation, as determined by immunogold labelling. We hypothesize that immune system changes are associated with increased immune complex trapping by hypertrophic FDCs expressing PrP Napoli molecules at the plasmalemma of dendrites, and that this process is exaggerated by immune system stimulation. Contrary to previous dogma, these results show that a pathological response within the immune system follows scrapie infection.

Animals↗
PubMedDate not supplied

Thermolysis of coenzymes B12 at physiological temperatures: activation parameters for cobalt-carbon bond homolysis and a quantitative analysis of the perturbation of the homolysis equilibrium by the ribonucleoside triphosphate reductase from Lactobacillus leichmannii.

The kinetics of the thermolysis of 5'-deoxyadenosylcobalamin (AdoCbl, coenzyme B12) in aqueous solution, pH 7.5, have been studied in the temperature range 30-85 degrees C using AdoCbl tritiated at the adenine C2 position and the method of initial rates. Combined with a careful analysis of the distribution of adenine-containing products, the results permit the dissection of the competing rate constants for carbon-cobalt bond homolysis and heterolysis. After correction for the temperature-dependent occurrence of the much less reactive base-off species of AdoCbl, the activation parameters for homolysis of the base-on species were found to be delta H++homo,on = 33.8 +/- 0.2 kcal mol-1 and delta S++homo,on = 13.5 +/- 0.7 cal mol-1 K-1, values not significantly different from those determined by Hay and Finke (J. Am. Chem. Soc. 108 (1986) 4820), in the temperature range 85-115 degrees C. In contrast, the heterolysis of base-on AdoCbl was characterized by a much smaller enthalpy of activation (delta H++het,on = 18.5 +/- 0.2 kcal mol-1) and a negative entropy of activation (delta S++het,on = -34.0 +/- 0.7 cal mol-1 K-1) so that heterolysis, which is minor pathway at elevated temperatures, is the dominant pathway for AdoCbl decomposition at physiological temperatures. Using literature values for the rate constant for the reverse reaction, the equilibrium constant for AdoCbl homolysis at 37 degrees C was calculated to be 7.9 x 10(-18). Comparison with the equilibrium constant for this homolysis at the active site of the ribonucleoside triphosphate reductase from Lactobacillus leichmannii shows that the enzymes shifts the equilibrium constant towards homolysis products by a factor of 2.9 x 10(12) (17.7 kcal mol-1) by binding the thermolysis products with an equilibrium constant of 7.1 x 10(16) M-2, compared to the bonding constant for AdoCbl of 2.4 x 10(4) M-1.

Binding Sites↗
PubMedDate not supplied

Cauda equina syndrome. Implications for the orthopaedic nurse in a clinical setting.

Cauda equina syndrome (CES) is a presentation of signs and symptoms that indicate nerve compression involving one or more of the nerve roots in the lumbar spine. The Clinical Nurse Specialist working in a general orthopaedic practice must become familiar with the presentation of CES to appropriately assess the patient and alert the physician. Prompt and accurate care of the patient is critical when cauda equina syndrome is suspected to minimize permanent nerve damage. This article describes the syndrome, its signs and symptoms, basic triage techniques, plan of care, and recovery for the patient with cauda equina syndrome.

Cauda Equina↗
PubMedDate not supplied

Decision-making about genetic testing among women at familial risk for breast cancer.

OBJECTIVE: Recent identification of the breast-ovarian cancer susceptibility gene BRCA1 and the breast cancer susceptibility gene BRCA2 have raised the possibility of clinical genetic testing for breast cancer susceptibility. This study examined decision-making about future susceptibility testing among women at familial risk for breast cancer. Based on the transtheoretical model, it was hypothesized that readiness to undergo testing would be related to the ratio between the perceived advantages (pros) and disadvantages (cons) of learning one's susceptibility status. METHODS: Seventy-four women with one or more first-degree relatives with breast cancer were recruited before a routine mammogram. Participants completed measures assessing readiness to undergo testing, perceived pros and cons of testing, and perceived breast cancer risk. Family history data was used to calculate empiric genetic risk of developing breast cancer. RESULTS: Forty-six per cent of participants planned to seek genetic testing as soon as possible, 35% planned to seek testing in the future, and 19% did not plan to seek testing. As expected, greater readiness to undergo testing was associated with a positive decisional balance (pros > cons). Older age and greater perceived risk (but not empiric risk) also were associated with greater readiness. CONCLUSION: The readiness of many women to seek breast cancer susceptibility testing can be attributed, in large part, to their perceptions that the advantages outweigh the disadvantages. Examination of these perceptions suggests that notification of carrier status may have significant effects on women's psychological well-being and breast cancer surveillance and prevention behaviors.

Adult↗
PubMedDate not supplied

Diagnostic evaluation of patients with histiocytosis X.

The natural history of histiocytosis X was reviewed in 52 patients to identify the characteristics of patients with localized versus disseminated disease. Two categories of patients were identified. Older patients with solitary or multiple bone lesions constituted a low-risk group. This group had a high rate of development of new bone lesions (55% were asymptomatic) but an excellent prognosis. Patients with soft tissue involvement constituted a group at high risk for disease progression and organ dysfunction. These patients required a more extensive diagnostic workup and systemic treatment. A diagnostic algorithm is proposed to identify these two groups.

Adolescent↗