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Biomedical subjects

C Mitchell

Publications and source records attributed to C Mitchell.

At least 109 records · Page 6Linked to original sources
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↗
PubMed1983

Lower respiratory tract symptoms in Queensland schoolchildren. The questionnaire: its reliability and validity.

Respiratory symptoms and ventilatory function were recorded on 4549 Queensland schoolchildren. Previously parents of 67 children on two occasions showed that key questions on wheezy breathing and productive cough were reliable, with agreement of responses in 97% and 91% of subjects. These two questions divided the children into four main groups: Group A, those children with attacks of asthma or of wheezy breathing; Group B, those with attacks of cough with sputum; Group AB, those with both symptoms; and Group N, those with neither symptom. The validity of the questionnaire was examined by relating question responses to ventilatory function expressed as normalized residuals. Mean (+/- SD) normalized FEF 25-75 residuals for the major groups were: N, 0 +/- 1.00; B, -0.10 +/- 1.00; A, -0.26 +/- 1.10; and AB, -0.50 +/- 1.07. In subjects with wheeze, residuals distinguished subjects on a basis of frequency of wheeze, total number of attacks, and the association with breathlessness. The proportion of eight year olds in each group (N, B, A and AB) was 44%, 33%, 2.6%, and 20.5% respectively; and of twelve year olds, 52%, 28%, 2.7%, and 18.1%. These results contrast with those of a comparable survey of Tasmanian seven year olds where the proportion was 51%, 33%, 1.8%, and 14.4% respectively.

Asthma↗
PubMed1983

The masking of tinnitus with pure tones.

The tinnitus of 32 subjects was studied. The tinnitus in each subject was matched to tones and bands of noise. Tones were then used to determine masking curves. Four types of masking curves were found. These types are similar to those previously reported. The findings also supported previous studies where tinnitus masking curves were found to differ significantly from conventional masking curves. Audiometric curves were grouped according to severity of hearing loss in order to determine whether subjects with similar threshold curves had similar masking curves. Similarities were noted in only one group: those with the least hearing loss. The relation between masking curves and the success of masking therapy is discussed.

Audiometry↗
PubMed1983

Management of the acute asthma attack at home.

Asthma is a disease of remission and exacerbation but the combination of optimal interval therapy with early aggressive self initiated medication during deterioration (particularly oral corticosteroids) should prevent the crises which require emergency intervention. The first and last words in acute asthma management must be prevention and prevention.

Acute Disease↗
PubMed1982

Metabolism of immunoglobulin A in lactating mice: origins of immunoglobulin A in milk.

The metabolism of albumin and IgA was studied in normal and lactationg mice. Lactation resulted in significant changes in the metabolism of these proteins. The serum albumin concentration was lowered from 47 mg/ml in normals to 24 mg/ml in lactating mice. However, only a slight decrease in the serum concentration of IgA was observed during lactation. The proportion of polymeric and monomeric IgA in serum and milk was evaluated by gel exclusion chromatography. The onset of lactatin led to a rise in the proportion of polymeric IgA (P-IgA) in serum from 37% to 51%. The proportion of P-IgA in milk was 65% and remained constant throughout lactation. P-IgA and albumin were shown to be efficiently transferred from the serum of lactating mice into their milk. Serum decay studies were performed to evaluate the turnover of the serum pools during lactation. The rates of disappearance from the serum of isotopically labeled albumin and P-IgA were observed to increase dramatically during lactation, suggesting that both of these two mild proteins might be derived at least in part from the serum. The sites of synthesis of mild IgA (local vs. extra-mammary gland) were evaluated by determining the extent of dilution of isotopically labeled serum IgA during transport through the mammary gland into the milk. Early in lactation, the majority of the IgA in mouse milk appeared to be derived from distant sites and transferred via the blood to the mammary gland. However, by day 8 of lactation, the isotopically labeled P-IgA in milk was significantly diluted by the IgA synthesized in the mammary gland. Albumin and IgG were not diluted by local synthesis indicating that these proteins were exclusively serum-derived.

Animals↗
PubMed1982

Postoperative respiratory morbidity: identification and risk factors.

Two hundred consecutive patients admitted for general surgery were studied prospectively to evaluate the contribution of risk factors to postoperative respiratory morbidity (PORM). PORM was expressed both in terms of individual clinical features present on the second postoperative day (when the incidence was greatest), and as an aggregate score incorporating many clinical features. The importance of recognised risk factors, such as previous respiratory disease, cigarette smoking, upper abdominal procedures and the duration of surgery was confirmed, in that these factors were associated with some of the individual clinical features of PORM. The relative importance and independent contribution of these risk factors were assessed by their association with the aggregate score. A naso-gastric tube (NGT) present for 24 hours postoperatively was the factor more associated with PORM. The NGT identified patients at risk more clearly than, and independently of, the next most important factor, upper abdominal surgery. The duration of surgery did not contribute to PORM after the influence of NGT and site of surgery had been considered. Previous respiratory disease predisposed to PORM, and was best identified by, in order of importance, an observed productive cough, a reduced one second forced expiratory volume, and purulent sputum. After the incidence of these factors had been considered, cigarette smoking and a history of a chronic productive cough did not contribute further to PORM.

Abdomen↗
PubMed1981

Prevalence of respiratory morbidity in Brisbane waterside workers. A study of possible asbestos-related disease.

Ninety-eight Brisbane waterside workers who had been exposed to several dusts, particularly that of asbestos fibre, were studied. Forty-nine subjects complained of dyspnoea while walking uphill, 46 had basal endinspiratory crepitations, and chest X-ray films showed small irregular opacities in 41 subjects and pleural abnormalities in 27 subjects. Internal comparisons showed that ventilatory function was correlated significantly with duration of employment on the wharves, independently of the effect of age and total cigarette consumption. Forced vital capacity decreased by 20 mL/year on wharves, and one-second forced expiratory volume by 34 mL/year, in excess of the age-related decrease. These findings suggest that these workers have developed parenchymal lung disease probably related to asbestos-dust exposure on the wharves.

Adult↗
PubMed1981

DNA modification in rat lungs following intratracheal or subcutaneous administration of 4-nitroquinoline-1-oxide, benzo[a]pyrene or 2-aminoanthracene.

Benzo[a]pyrene (BP)-, 2-aminoanthracene (2AA)- and 4-nitroquinoline-1-oxide (4NQO)-mediated DNA modification were investigated in rat lungs by using alkaline sucrose gradient sedimentation. The exposure-route, the physicochemical nature of the administered compound and the number of treatments were all important in determining the extent of DNA modification. 4NQO produced qualitatively similar modification whether instilled intratracheally (i.t.) as a suspension or injected subcutaneously (s.c.) in a soluble form. BP and 2AA produced no DNA alteration when injected s.c; they did, however, modify DNA sedimentation when instilled as a suspension, but not until 24 h after treatment. Furthermore, BP caused no DNA modification at any sampling time when instilled in a lipid solvent. In contrast to the DNA modification observed at 24 h after a single i.t. treatment with a BP suspension, no such alteration was detected 12 or 24 h after the last of 5 similar daily treatments. These results are discussed with respect to mechanisms of differential transport, clearance and metabolism of administered carcinogens.

4-Nitroquinoline-1-oxide↗