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Biomedical subjects

A Hart

Publications and source records attributed to A Hart.

At least 19 recordsLinked to original sources
PubMed1992

The effectiveness of differential moments in establishing and maintaining anchorage.

The purpose of the present study is to both clinically and cephalometrically investigate maximum and minimum anchorage control in four first premolar extraction cases, using the "differential moments (torque)" concept. Data were obtained from the pretreatment and posttreatment lateral cephalometric radiographs of 30 patients, 13 boys and 17 girls, who were treated exclusively with "differential torque" mechanics. Of the 30 patients selected, 18 were classified as having Angle Class I malocclusion (crowded and/or bimaxillary alveolar protrusion) and 12 as having Angle Class II, Division 1 malocclusion (crowded and/or severe overjet). The sample was divided into two groups, according to the severity of crowding. Subjects with 6.0 mm or more of crowding, in at least one quadrant per arch, were placed in the maximum anchorage group, suggesting the desirability of maintaining a relatively stable position of the anchor unit. Subjects with less than 6.0 mm of crowding per quadrant were categorized as moderate or minimum anchorage cases, indicating desirability of some intermediate degree of controlled movement of the anchor teeth. Comparison of the two groups in each malocclusion category revealed their comparability with respect to molar relationship and incisor overjet. The major finding of this study is the clinical effectiveness of differential moments as a means of controlling intraoral anchorage. It proves to be optimal and controllable for clinical purposes, regardless of the type of malocclusion or the severity of crowding.

Adolescent↗
PubMed1991

Ultrastructural morphology of Cowdria ruminantium in midgut epithelial cells of adult Amblyomma hebraeum female ticks.

Amblyomma hebraeum male and female ticks, experimentally infected as larvae with the Ball 3 stock of Cowdria ruminantium, were fed on a heartwater susceptible sheep. The initial attachment of the males was required as a pre-requisite for female attachment. Reticulate bodies were the predominant morphologic form of Cowdria observed in gut epithelial cells after 1-3 days of feeding. Single intermediate bodies and no elementary bodies were observed. Organisms were found within a membrane-bound vacuole and each organism had a double-unit membrane. Infrequently colonies contained homogeneous electron-dense inclusions. Groups of Cowdria organisms within a haemocyte suggested a possible dissemination of organisms from the gut to various other tissues by haemocytes.

Animals↗
PubMed1990

Bone mineral density after adjuvant chemotherapy for premenopausal breast cancer.

Lumbar bone mineral density (BMD) determination by dual photon absorptiometry was used to study the influence of adjuvant chemotherapy for premenopausal breast cancer on the risk of premature osteoporosis. Six cycles of combination chemotherapy caused ovarian failure in 31 of 44 (71%) women, amenorrhoea mostly already beginning during treatment. In contrast, only seven of 44 (16%) women, who were pair-matched for age and year of breast cancer surgery and had not been treated with chemotherapy, were post-menopausal at the time of measurement. The mean interval after breast surgery was 3.5 years. The significantly decreased BMD in the treated group (1.17 compared to 1.29 g cm-2) could only be explained by the high incidence of menopause in these women, which on average occurred 10 years prematurely. Extrapolation of these findings suggests that adjuvant chemotherapy may precipitate osteoporotic fractures by some 10 years in a considerable proportion of women cured of premenopausal breast cancer.

Adult↗
PubMed1989

Evaluation of a short-stay program for patients undergoing mastectomy.

Two hundred twenty-eight patients were included in a retrospective study to evaluate the morbidity and feasibility of early discharge after mastectomy. Group I (early discharge, n = 75) patients were given pre- and postoperative instruction related to wound and drain care. Group II (concurrent control, n = 44) was given similar postoperative instruction, but received no preoperative teaching. Group III (historical controls, n = 109) underwent surgery during a period of more liberal hospitalization and discharge policies. The groups were similar in age, cultural background, operations performed, and pathologic diagnosis. Length of stay for groups I, II, and III was 5.5 +/- 0.4, 3.5 +/- 0.2, and 8.6 +/- 0.3 days, respectively. Groups I and II had a significantly shorter stay than group III. There was no difference among the groups for the presence of wound erythema, rate of primary healing, seroma formation, or wound infection. The practice of same-day admission and early discharge to limit length of stay for patients undergoing mastectomy is safe and effective.

Breast Neoplasms↗
PubMed1988

Mastectomy or conservation: the patient's choice.

STUDY OBJECTIVE: To determine whether, if given the choice, patients with breast cancer would prefer mastectomy or conservation treatment, neither treatment having been shown to be preferable. DESIGN: Non-randomised case series with 28 patients interviewed after two years and all followed up. SETTING: Secondary care referral centre. PATIENTS: 153 women, aged less than 65, with T1, T2, N1, and N0 tumours of the breast given the choice of treatment (that is, all eligible patients from December 1979). INTERVENTIONS: Patients were asked, after information and counselling, which treatment they would prefer. The chosen treatment was given without further question. Mastectomy included node sampling and local radiotherapy if indicated. Conservation treatment comprised excision of the lump, external radiotherapy, and irridium wire implant to tumour bed. MAIN RESULTS: Conservation treatment was chosen by 54 women and mastectomy by 99. Reasons for preferring mastectomy included desire for rapid treatment for domestic or employment reasons and fear of possibility of future mastectomy. Only two of the sample interviewed regretted their choice. During limited follow up no advantages to either form of treatment were seen in terms of recurrence or survival. CONCLUSIONS: Patients with breast cancer are capable of choosing treatment and should play a part in deciding which treatment to have. They do not automatically choose to retain the breast.

Adult↗
PubMed1987

Buoyant density fluctuations during the cell cycle of Bacillus subtilis.

A simple rapid method for preparing synchronous cultures of Bacillus subtilis has been used to investigate changes in density during the cell cycle. Asynchronous cells separated on a stepped Percoll density gradient had a mean cell density of 1.117 g ml-1 +/- 0.004. Samples from a synchronous culture exhibited variation (ca. 1.5%) in mean cell density which was greatest at the onset of cell division. An asynchronous control culture showed little variation in density. These results are discussed in relation to previous work on Escherichia coli.

Bacillus subtilis↗
PubMed1987

Nondetectable levels of interferon gamma is a critical host defense during the first day of herpes simplex virus infection.

Previous studies have demonstrated the importance of IFN alpha/beta in resistance to primary viral infections. However, the role of IFN gamma in primary infections is unclear. The present studies were undertaken to determine whether IFN gamma induction was an important early host defense against primary HSV infection. The approach was to block the IFN gamma response with antibodies to IFN gamma prior to infection and at various times post-infection (p.i.). The data indicates that treatment of mice with anti-IFN gamma prior to infection enhanced mortality (89% vs 37%). Anti-IFNs given at various times post HSV challenge proved most effective within the first 24 h of infection. The above results suggest for the first time that IFN gamma mediates important host defense(s) early during primary HSV infection. Similar results were obtained using antibody to IFN alpha/beta.

Animals↗
PubMed1987

Prognostic implication of hyperdiploidy as based on DNA flow cytometric measurement in childhood acute lymphocytic leukemia--a multicenter study.

The pretreatment distribution of DNA content was determined in the leukemic blasts of 114 children with standard risk acute lymphocytic leukemia. The patients were admitted to four different centers for pediatric oncology, participating in a national study ALL-V. In 39 of 107 evaluable patients (36.4%), a single aneuploid leukemic line was detected with a median DNA Index of 1.22 (range 1.10-1.40). These hyperdiploid patients did not differ from those with diploid disease for the presenting features of age, sex, FAB classification, immunophenotype, or white blood cell count. However, patients with hyperdiploid acute lymphocytic leukemia had a significantly longer (p = 0.021) disease-free survival after a median observation period of 52 months. These observations indicate that routinely applied flow cytometry of DNA content can identify a fairly large subgroup of children with standard risk acute lymphocytic leukemia who have a low probability of relapse. It may be considered to exempt these patients from more intensive treatment regimens.

Aneuploidy↗
PubMed1987

Ultrastructural features of Cowdria ruminantium in midgut epithelial cells and salivary glands of nymphal Amblyomma hebraeum.

Colonies of Cowdria ruminantium were studied in midgut epithelial cells and salivary gland acini of nymphal Amblyomma hebraeum that were infected experimentally as larvae. Colonies were found in both tissues and studied with light and electron microscopy. Colonies observed within gut cells frequently contained 2 types of the organism: electron-dense and reticulated forms. The morphology of colonies from salivary glands, as seen with light microscopy, varied from compact, densely-staining, small colonies to larger ones in which individual organisms were apparent. With electron microscopy, most organisms in salivary glands were reticulated and appeared to be dividing by binary fission. In both types of host cells, colonies often contained a dense inclusion to which reticulated organisms were adhered.

Animals↗
PubMed1986

Ultrastructural and biochemical changes in human jejunal mucosa associated with enteropathogenic Escherichia coli (0111) infection.

A case of prolonged diarrhoea following Escherichia coli 0111 gastroenteritis is reported. Electron microscopy of the jejunal biopsy revealed effacement of the brush border and attachment of bacteria by pedestal formation. Specific activities of brush border enzymes showed marked depression of disaccharidases, zinc-resistant alpha-glucosidase, and alkaline phosphatase. In contrast, marker enzymes for basolateral membranes and endoplasmic reticulum were unaffected. The biochemical changes support the pathogenic mechanism suggested by ultrastructural studies previously reported.

Biopsy↗
PubMed1985

Hormonal regulation of four urea cycle enzymes in postnatal rat liver in organ culture.

The administration of hydrocortisone to 3- to 15-day-old rats increased the levels of hepatic argininosuccinate synthetase (ASS) and arginase. In 13-day-old rat liver explants maintained in organ culture, ornithine carbamoyltransferase (OTC), carbamoylphosphate synthetase (CPS) and arginase were stimulated by betamethasone. Actinomycin D prevented the responses of the latter two enzymes. Dibutyryl cyclic AMP raised OTC, CPS, ASS and arginase in vitro. The responses of the latter three enzymes were blocked by cycloheximide and puromycin and partially inhibited by actinomycin D. The simultaneous presence of betamethasone and dibutyryl cyclic AMP in the culture medium raised CPS and OTC in an additive manner. The sequential treatment of the cultures with betamethasone followed by dibutyryl cyclic AMP increased CPS and arginase synergistically and amplified the response of ASS to dibutyryl cyclic AMP.

Animals↗