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Biomedical subjects

R B Hall

Publications and source records attributed to R B Hall.

6 recordsLinked to original sources
PubMed1999

The chloroplast small heat shock protein undergoes oxidation-dependent conformational changes and may protect plants from oxidative stress.

The nuclear-encoded chloroplast-localized Hsp21 is an oligomeric heat shock protein (Hsp), belonging to the protein family of small Hsps and alpha-crystallins. We have investigated the effects of high temperature and oxidation treatments on the structural properties of Hsp21, both in purified recombinant form and in transgenic Arabidopsis thaliana plants engineered to constitutively overexpress Hsp21. A conformational change was observed for the 300 kDa oligomeric Hsp21 protein during moderate heat stress (< or =40 degrees C) of Arabidopsis plants, as judged by a shift to lower mobility in non-denaturing electrophoresis. Similar changes in mobility were observed when purified recombinant Hsp21 protein was subjected to an oxidant. Exposure of Hsp21 protein to temperatures above 70 degrees C led to irreversible aggregation, which was prevented in presence of the reductant dithiothreitol. The transgenic plants that constitutively overexpressed Hsp21 were more resistant to heat stress than were wildtype plants when the heat stress was imposed under high light conditions. These results suggest that the physiological role of Hsp21 involves a response to temperature-dependent oxidative stress.

Arabidopsis↗
PubMed1995

Differentiation of segmented and band neutrophils during the early newborn period.

This prospective study evaluated the degree of inter-reader variability in the identification of segmented and band neutrophils from blood smears of full-term, healthy neonates. Wide inter-reader differences of band neutrophil identification and the immature to total neutrophil ratio were observed. Because of poor correlation between evaluators of the same blood smear, the clinical utility of the manual differential leukocyte count in the evaluation of neonates is limited.

Blood Specimen Collection↗
PubMed1994

Peripheral leukocyte count and leukocyte indexes in healthy newborn term infants.

PURPOSE: This study was designed to determine normal values for the peripheral leukocyte count and leukocyte indexes in healthy term neonates at a specific time after birth. METHODS: We prospectively enrolled 193 healthy term-gestation neonates with no identifiable perinatal risk factors for sepsis. At 4 hours of age a blood sample was collected by warmed heel stick. An automated Coulter complete blood cell count and a 100-cell manual differential leukocyte count were performed on each sample. The differential count was performed by a single hematopathologist unaware of the clinical status of each infant. Perinatal factors were identified by review of the mothers' and infants' hospital records. RESULTS: The mean ratio of immature to total neutrophils was 0.16 (SD 0.10), and the 10% to 90% range was 0.05 to 0.27. The mean leukocyte count was 24.06 x 10(9)/L (24,060/mm3), and the 10% to 90% range was 16.2 to 31.5 x 10(9)/L (16,200 to 31,500/mm3). Neutropenia, < 1.5 x 10(9)/L (1500/mm3) segmented plus band form neutrophils, was not observed. Of all the perinatal factors studied, only the duration of stage 1 labor was found to be associated with significant elevations in the leukocyte and absolute neutrophil counts. CONCLUSIONS: Previously published normal ranges for leukocyte indexes in healthy newborn infants during the early neonatal period are too restrictive; reference standards should be broadened.

Blood Cell Count↗
PubMed1985

Periosteal osteosarcoma.

An analysis of 6 patients with periosteal osteosarcoma treated by the authors along with a review of 55 patients reported in the literature demonstrates that periosteal osteosarcoma is distinctly different from conventional osteosarcoma or periosteal chondrosarcoma. Periosteal osteosarcoma is a less aggressive tumor than conventional osteosarcoma. It is a relatively well-differentiated chondroblastic osteosarcoma occurring on the surface of the long bones of the extremities. Three patients demonstrated frank medullary invasion of tumor, two grossly and one microsurgically. Patients treated with marginal resection had a 70% local recurrence rate. Patients receiving wide resection or primary amputation have survived longer with less recurrence of disease. Overall, 10 of 61 patients are dead with metastatic disease with a mean reported follow-up of 6 years and 7 months. Adjunctive therapy has been of no demonstrable aid in terms of prolonging survival. Medullary extension of this tumor should not be used to exclude this diagnosis. The authors believe that the treatment of choice is wide resection without adjunctive chemotherapy.

Adolescent↗