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Biomedical subjects

J S Chapman

Publications and source records attributed to J S Chapman.

At least 37 records · Page 2Linked to original sources
PubMed1986

Dust exposure, dust recovered from the lung, and associated pathology in a group of British coalminers.

The relation between dust exposure, retained lung dust, and pneumoconiosis have been examined in 430 dead coalminers who had participated in a large scale epidemiological survey of respiratory health. The men were divided into three groups depending on the presence of particular lesions in their lungs. Lungs containing no fibrotic lesions in excess of 1 mm were included in the "M" group, those with fibrotic lesions of between 1 mm and 9 mm in diameter were included in the "F" group, and those with any lesion 10 mm or more were categorised as having progressive massive fibrosis (PMF). The men were further divided into four groups according to the rank of coal mined at the colliery of employment. The mean weight of lung dust increased over the pathological range (M----F----PMF) regardless of the rank of coal mined. The men with PMF had not received unusually high exposures to dust in life but were found to have accumulated more dust in their lungs per unit of dust exposure than men without PMF, providing further evidence for differences in the patterns of deposition or clearance, or both, of dust in these men compared with those who do not develop PMF. For men who had mined the higher rank coals there was no difference in the composition of the lung dust between the pathological groups. Lungs from men mining low rank coal, however, showed a striking increase in the proportion of ash over the pathological groups (M, F, and PMF). In men who had mined low rank coal the proportion of ash in the airborne dust to which they had been exposed and in the dust retained in their lungs was, as expected, greater than in men who had worked with higher rank coals. For the same men, and particularly associated with the presence of some dust related fibrosis, the proportion of ash in retained dust was higher than that in the dust to which the men were exposed suggesting the occurrence of selective deposition or retention of the mineral components of dust in this group.

Aged↗
PubMed1985

Microanalyses of lesions and lymph nodes from coalminers' lungs.

The dust content and composition of lesions and hilar lymph nodes from the lungs of British coalworkers have been examined. Samples of macules, fibrotic nodules, and massive fibrosis (both peripheral and central sites) were dissected from 49 lungs. The highest mean dust concentrations (about 20%) were found in nodules and massive fibrosis. Overall there were no significant differences between the selected lesion types and their respective whole lung dust composition, although the central sites of massive fibrosis were found to contain on average a higher proportion of coal and a lower proportion of ash and its measured constituents, quartz and kaolin plus mica, than the edge of the lesion (p less than 0.001 for each component). There were striking differences between recovered lung and lymph node dusts. An examination of 180 specimens showed a mean quartz in lymph node dust of 20.3% compared with 6.1% in lung dust. As expected the proportion of quartz was greater in lymph nodes and lungs from men who had worked "low" rank (high ash) coal. By contrast with the corresponding figures for lung dusts, however, the mean proportion of quartz in nodes did not increase over the pathological range of pneumoconiotic lung disease. On average the proportions of kaolin and mica in lymph nodes reflect those found in lungs. The lymphotrophic nature of quartz was clearly shown although it was not possible to show an association between this clearance pathway and any particular type of lesion.

Coal↗
PubMed1984

Comparison of radiographic appearances with associated pathology and lung dust content in a group of coalworkers.

The pathology and dust content of lungs from 261 coalminers in relation to the appearances of their chest radiographs taken within four years of death were examined. Radiological opacities of coalworkers' pneumoconiosis were more profuse the more dust was retained in lungs. Among the men who had mined low rank coal--that is, with a relatively high proportion of ash--the increase in profusion was most closely related to the ash component of the dust, whereas in men who had mined high rank coal both coal and ash increased in the lungs in relation to radiological profusion. The fine p type of opacity was found to be associated with more dust and a higher proportion of coal and less ash than the nodular r opacity, and was also more likely to be associated with emphysema. The pathological basis of the different types of opacity found on the radiographs of coalminers related to the number, size, and nodularity of the dust lesions. Larger fibrotic lesions were likely to appear as r opacities, whereas fine reticular dust deposition was most likely to present as p opacities, q opacities showing a mixture of appearances. The study has shown that the composition of dust retained in the lung, as well as its amount, makes an important contribution to the radiographic appearances of pneumoconiosis. In particular, the r type of lesion on the radiograph of a low rank coalminer indicates the possibility of a silicotic like lesion.

Coal Mining↗
PubMed1984

Emphysema and dust exposure in a group of coal workers.

The lungs of 450 coal miners who had been studied previously in a long-term epidemiologic project at 24 British mines have been examined post-mortem for signs of dust-related fibrosis and emphysema. Reliable estimates of cumulative (working-life) exposures to respirable mine dust were available for 342 of the men. The relative frequency of emphysema increased with age at death, and both panacinar and centriacinar emphysema occurred more frequently in smokers than in nonsmokers. The proportion of subjects with any emphysema was 47% in 92 men with no palpable dust lesions, 65% in 183 with small, simple pneumoconiotic lesions, and 83% in 175 miners with massive fibrosis (PMF). The chance of finding centriacinar emphysema in those with PMF increased significantly with increasing exposure to coal dust in life (p less than 0.025). A similar but less convincing relationship was found in those with simple pneumoconiosis (p less than 0.11), but in both groups, increasing amounts of ash with a given exposure to coal reduced the probability of finding centriacinar emphysema. The occurrence of centriacinar emphysema was associated also with increasing amounts of dust retained in the lungs. A preliminary exploration of this association did not support the hypothesis that emphysematous lungs clear dust less efficiently. We conclude that the association observed between exposure to respirable coal dust and emphysema in coal miners indicates a causal relationship. However, because it can be demonstrated only for men whose lungs show some dust-related fibrosis, it is suggested that the extent and nature of such fibrosis may be a crucial factor in determining the presence of centriacinar emphysema.

Age Factors↗
PubMed1983

Regulation of expression of nitrate and dinitrogen assimilation by anabaena species.

Anabaena sp. strain 7120 appeared more responsive to nitrogen control than A. cylindrica. Growth in the presence of nitrate strongly repressed the differentiation of heterocysts and fixation of dinitrogen in Anabaena sp. strain 7120, but only weakly in A. cylindrica. Nitrate assimilation by ammonium-grown cultures was strongly repressed in Anabaena sp. strain 7120, but less so in A. cylindrica. The repressive effect of nitrate on dinitrogen assimilation in Anabaena sp. strain 7120, compared to A. cylindrica, did not correlate with a greater rate of nitrate transport, reduction to ammonium, assimilation into amino acids, or growth. Although both species grew at similar rates with dinitrogen, A. cylindrica grew faster with nitrate, incorporated more NO(3) into amino acids, and assimilated (transported) nitrate at the same rate as Anabaena sp. strain 7120. Full expression of nitrate assimilation in the two species occurred within 2.5 h (10 to 14% of their generation times) after transfer to nitrate medium. The induction and continued expression of nitrate assimilation was dependent on protein synthesis. The half-saturation constants for nitrate assimilation and for nitrate and ammonium repression of dinitrogen assimilation have ecological significance with respect to nitrogen-dependent growth and competitiveness of the two Anabaena species.

Journal Article↗
PubMed1983

Glutamine and glutamate transport by Anabaena variabilis.

Anabaena variabilis, a dinitrogen-fixing cyanobacterium, has high- and low-affinity systems for the transport of glutamine and glutamate. The high-affinity systems have Km values of 13.8 and 100 microM and maximal rates of 13.2 and 14.4 nmol X min-1 X mg of chlorophyll a-1 for glutamine and glutamate, respectively. The low-affinity systems have Km values of 1.1 and 1.4 mM and maximal rates of 125 and 100 nmol X min-1 X mg of chlorophyll a-1 for glutamine and glutamate, respectively. Glutamine was unable to support growth of A. variabilis in the absence of any other nitrogen source, and glutamate alone at 500 microM was inhibitory to its growth. The analog L-methionine-DL-sulfoximine (MSX) was transported by a high-affinity system with a Km of 34 microM. Competition experiments and the transport characteristics of a specific class of MSX-resistant mutants imply that glutamine, glutamate, and MSX share a common component for transport. A second class of MSX-resistant mutants had a glutamine synthetase activity with altered affinity constants for glutamine and glutamate relative to the wild-type enzyme.

Biological Transport↗
PubMed1981

Initial roentgenographic manifestations of pulmonary Mycobacterium tuberculosis, M kansasii, and M intracellularis infections.

The initial radiographic features of 188 patients with pulmonary infections due to Mycobacterium tuberculosis were compared to 184 patients with M kansasii and 100 patients with M intracellularis infections. The patients were all from the University of Texas Health Center at Tyler, all had at least two positive sputum cultures and no other potential pathogen, and none had a past medical history of any type of tuberculosis. The comparison showed that all three organisms have a strong tendency to produce cavitary infiltrates in the posterior portions of the upper lobes. No distinctive or pathognomonic feature could be found. The atypical organisms were more likely to produce thin-walled cavities and far advanced unilateral disease, but both of these patterns also occurred with M tuberculosis. Endobronchial spread and volume loss were common in all three diseases. The only definite difference seems to be the absence of a primary or juvenile form of atypical tuberculosis and a much greater incidence of empyema and postprimary pleural effusions with M tuberculosis. In an individual case, the roentgenographic manifestations of the three diseases are indistinguishable.

Aged↗
PubMed1980

Selection of primary care as a medical career: demographic and psychosocial correlates.

A study analyzing demographic and psychosocial correlates associated with the selection of primary care as a medical career was conducted on 357 physicians who were graduated from medical school between 1963 and 1966. Results suggest that individuals who were reared in smaller communities, who were among the younger siblings of their family, and who exhibited a strong pattern of socialization at home and school tended to choose a primary care specialty. The findings also suggest that if all other factors are equal and if production of primary care physicians is an important goal, medical school admission committees might consider including cross-validated psychosocial and demographic variables in selecting applicants to medical schools.

Adult↗
PubMed1979

Hospitals and medical schools as factors in the selection of location of practice.

A study analyzing the relationship between the state in which a physician practices and the location of residency training was conducted using as subjects 467 individuals who entered graduate medical training programs at the University of Texas Southwestern Medical School at Dallas. The study population included physicians who were graduated from medical schools between 1955 and 1969 and who entered a phase of graduate training (internship/residency) at one of Southwestern Medical School's affiliated teaching hospitals. Results of the study support the conclusions of an earlier report that stressed the influence of the location of residency training in retaining physicians in Texas. The statistical findings indicate that if all other factors are equal, additional residency positions filled by graduates of medical schools in the same state might aid in increasing the retention rate of medical practitioners there.

Education, Medical↗
PubMed1979

Pulmonary manifestations of Mycobacterium intracellularis.

Pulmonary manifestations in 114 patients with at least two sputum cultures positive for M. intracellularis, no history of any kind of tuberculosis, and not other potential pathogen are described. Even with these stringent diagnostic criteria, seven patients had normal chest radiographs and another seven had reticulonodular-appearing disease without a definite focus of infection. In the other 100 patients, 92% had infiltrates in the apical and/or posterior segments of the upper lobes, and 88% had cavitary disease. The cavities were usually multiple and frequently measured over 4 cm. Scarring and volume loss were common, occurring to some degree in 70% of upper lobe foci. Pleural effusions were uncommon (5%) and usually small. Adenopathy was less common (4%) and usually occurred with upper lobe disease in younger patients. Most patients had some degree of endobronchial spread (81%). The radiographic characteristics of Mycobacterium intracellularis are not believed distinctive enought to differentiate it from Mycobacterium tuberculosis.

Aged↗
PubMed1979

Influence of varied stimuli on development of motor patterns in the premature infant.

The premature infant is at risk for both mortality and morbidity. His writhing contributes to weight loss, and his extrauterine environment does not contain the multi-modality patterned afferent stimuli that impinge upon the developing brain in utero. Sound is the most effective modality to achieve concurrent decrement in motility along with enhancement of cortical activity. It was anticipated that subjects exposed to 5 minutes of patterned sound 6 times a day would, by 36 weeks gestation, evidence: (a) less gross motor activity, (b) the normal predominance of upper over lower limb activity, and (c) beginning laterality. The sample consisted of 80 males and 73 females whose gestational age at birth was 26--33 weeks. By random assignment 52 subjects were exposed to the routine ambient noise of the isolette and nursery, 50 to a tape recording of their mother's voice, and 51 to an orchestral arrangement of Brahm's Lullaby. Limb activity was measured just prior to discharge by accelerometers worn unilaterally for a 24-hour period on the ankle and wrist prior to transfer to the alternate side for an additional 24 hours. No statistically significant differences were demonstrated among the limb patterns of the 3 groups. Large intragroup variation in gross activity precluded demonstration of between-group differences. The majority of subjects evidenced predominance of upper limb activity and laterality.

Acoustic Stimulation↗