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Biomedical subjects

C Mitchell

Publications and source records attributed to C Mitchell.

At least 55 records · Page 3Linked to original sources
PubMed1988

Second malignant neoplasms in retinoblastoma. Fact and fiction.

Second malignant neoplasms (SMN) are distinct from primary neoplasms in site, time and histology. SMN may arise by chance or due to the influences of chemotherapeutic agents, therapeutic irradiation or genetic predisposition. Patients with the hereditary form of retinoblastoma (RB) appear genetically predisposed to the development of connective tissue tumours, particularly osteosarcoma. Therapeutic irradiation is an additional risk. Quantitation of the risk of SMN in RB patients may be influenced by selection biases and inappropriate analyses. Much of the biases in reported series arises from the limitations of single-centre studies. Loss of patients to follow-up, failure to adhere to properly defined criteria of SMN and to consider the risk of malignancy in the general population may have led to over-estimation of the risk of SMN in retinoblastoma patients.

Disease Susceptibility↗
PubMed1988

Dentate granule cells are essential for kainic acid-induced wet dog shakes but not for seizures.

The purpose of this study was to determine the role that dentate granule cells play in wet dog shakes (WDS), behavioral seizures, and hippocampal cell loss caused by systemic administration of kainic acid (KA). Rats were given bilateral injections of colchicine (COL) into the hippocampal formation to selectively lesion dentate granule cells. Two weeks later, they were injected subcutaneously with KA and were observed for WDS and seizures. Seizures were terminated with pentobarbital 2.5 hr after KA injection, and the rats were killed 48 hr later. The integrity of hippocampal cell populations and projections to the hippocampal formation from entorhinal cortex was assessed with radioimmunoassay and immunostaining for methionine-enkephalin (ME) and dynorphin (DYN) A, as well as with Timm and Nissl staining. Results indicate that COL injections eliminated KA-induced WDS, did not affect the latency to onset of seizures, and potentiated KA-induced cell loss in the CA3 region of hippocampus. COL lesions eliminated ME and DYN immunostaining of granule cells, but not ME immunostaining of entorhinal afferents to the dentate gyrus or Ammon's horn. These findings indicate that granule cells are an essential neuronal link in the expression of KA-induced WDS, but that seizures propagate along other pathways in the limbic system.

Animals↗
PubMed1987

New splinting materials.

Plaster of Paris (P.o.P.) bandage has been the pre-eminent external splinting material for over 150 years and from time to time synthetic alternatives have been tried. So far none has seriously challenged the dominance of P.o.P. as a primary or secondary material in the management of fractures. The recent introduction of Polyurethane coated fibreglass bandage appears to offer a more serious challenge than previous contenders. This technical note reviews bandage type splinting materials and explains some of the properties of the PU materials.

Bandages↗
PubMed1986

Red pigment in Bacillus megaterium spores.

Bacillus megaterium QM B1551 spores contained a unique red pigment in their membranes that was not found in other species. This red pigment, presumably a carotenoid, was synthesized about the time of dipicolinic acid synthesis during sporulation and was associated with the forespores. A yellow pigment was synthesized during sporulation in rich medium and was found in the mother cell compartment. Although the yellow pigment was also associated with spores, it could be removed by two different extraction procedures without impairing germination; it was absent when sporulation occurred in a minimal medium. Although the yellow pigment of the mother cell appeared to be dispensable, the red pigment may serve a more critical function, such as membrane stabilization.

Bacillus megaterium↗
PubMed1986

Enkephalin contained in dentate granule cells is important for kainic acid-induced wet dog shakes.

Kainic acid (KA) caused an initial decrease and a subsequent rebound in hippocampal enkephalin (ENK) in rats exhibiting wet dog shakes (WDS) without behavioral convulsions. Antibody to methionine-enkephalin but not dynorphin A(1-8) injected into lateral ventricles attenuated KA-induced WDS, as did naloxone. Granule-cell destroying injections of colchicine into ventral but not dorsal hippocampus caused a 60% reduction of hippocampal ENK and a complete elimination of KA-induced WDS. These studies suggest that release of granule cell ENK, which is 3 times more concentrated in ventral than dorsal hippocampus, plays an important role in KA-induced WDS.

Animals↗
PubMed1985

MMPI critical item characteristics of the DSM-III borderline personality disorder.

This study attempted to distinguish the borderline personality disorder (BPD) from other personality disorders (OPD) on the basis of the Lachar and Wrobel critical item list. Seventy-five male psychiatric inpatients with diagnoses fitting DSM-III criteria for BPD and OPD and ranging in age from 24 to 47 years completed the MMPI. Lachar's critical item set, composed of 111 items taken from the MMPI, was then selected from each of the 75 subjects' response items. BPD and OPD patients significantly differed on only the Lachar Substance Abuse subscale. Implications of this study are discussed with regard to the concept that personality structure involves a continuum of psychopathology. The Lachar critical item list provided support for drug abuse as part of the diagnostic criteria for BPD and displayed promise for identifying areas of psychopathology on which treatment may be focused.

Adult↗
PubMed1985

Respiratory disease in foundry workers.

A survey was carried out in a steel foundry in Brisbane to evaluate the nature and frequency of respiratory symptoms and to assess ventilatory function. The foundry used many moulding processes including the Furane, Isocure, Shell, carbon dioxide, and oil sand systems. Nasal symptoms and wheeze were often reported, particularly by workers in the general foundry and core shop, and on a semiautomated line. By contrast, workers in the aftercast section not exposed to fumes or vapours from the various moulding processes reported these symptoms less often. Of 46 workers exposed to moulding fumes and vapours, 11 had developed a wheeze while working at the foundry. Wheeze and other respiratory tract symptoms were often attributed by the workers to exposure to substances at work, particularly from the Shell process which uses phenol formaldehyde resin and hexamethylenetetramine. Symptoms were reported also, but less often, on exposure to materials used in the Furane process (urea formaldehyde and furfuryl alcohol) and the Isocure process (methylene diphenyl diisocyanate, phenol formaldehyde, and dimethylethylamine). Ventilatory function studied over Monday and Friday showed a small and inconsistent changes. The six subjects working on the semiautomated line showed a small decrease in FEV1 (+/- SEM) (208 +/- 70 ml) only on Monday; this differed significantly from that in 17 aftercast workers (9 +/- 50 ml, p less than 0.05). Ventilatory function recorded before work on Monday morning showed no evidence of chronic airway obstruction in any group. Most environmental measurements were below the threshold limit values (TLV) except in the general foundry, where furfuryl alcohol was detected at concentrations of up to 50 ppm and formaldehyde at 4 ppm. The onset of symptoms in relation to exposure to various fumes and vapours suggests that both irritant and hypersensitivity mechanisms are present. As environmental modifications had occurred recently the apparent hypersensitivity may relate to past exposure levels above the TLV.

Adult↗
PubMed1979

Reflection-impulsivity and the evaluation process.

The relationship between reflection-impulsivity, hypothese generation and testing, and evaluation of the quality of one's own solutions was explored in the framework of Kagan's theory. The Matching Familiar Figures test (MFF) and a pattern-matching task were administered to 94 children from 8-0 to 11-11 years. Multiple regression analyses and analyses of variance showed that children who were inaccurate on the MFF were more likely to offer a solution on the pattern-matching task before they had sufficient information to guarantee a correct solution and to make errors despite sufficient information to have avoided those errors. Thus reflection-impulsivity as measured by the MFF were related to 2 other measures of the evaluation process on another visual match-to-sample task. Only 1 of 3 hypothesis-testing variables was significantly related to MFF performance, and that relationship was rather small.

Child↗