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J A Chapman

Publications and source records attributed to J A Chapman.

At least 73 records · Page 4Linked to original sources
PubMed1986

Collagen self-assembly in vitro: electron microscopy of initial aggregates formed during the lag phase.

Initial aggregates formed in collagen self-assembly were visualized by electron microscopy, using formaldehyde to fix the state of aggregation at various points in the turbidimetric lag phase. Measurements of the length distributions of monomers and small oligomers show that the first-formed aggregates are dimeric, with the most prevalent dimer having a maximal (approximately equal to 4D; D = 67 nm) stagger between constituent molecules.

Animals↗
PubMed1986

Gastrointestinal obstruction associated with multiple-dose activated charcoal.

The development of a gastrointestinal obstruction associated with multiple doses of activated charcoal is described. A carbamazepine-intoxicated patient received 240 g of activated charcoal and a total of 600 mL magnesium citrate with the development of an ileus and a small-bowel obstruction. The patient also had episodes of emesis associated with charcoal administration. This case suggests that the use of multiple doses of activated charcoal may be associated with gastrointestinal obstruction, a previously unreported adverse effect. Further evaluation of the incidence of adverse effects associated with activated charcoal is needed to determine optimal therapeutic regimens.

Adult↗
PubMed1986

An unusual nitrofurantoin-induced drug reaction.

A case of drug-induced lupus erythematosus associated with erythema multiforme due to nitrofurantoin is presented. This case differs from those previously reported in that no pulmonary infiltrate was found. In 21 months, there was a complete clinical and serologic remission after nitrofurantoin was withdrawn from the therapeutic regimen.

Aged↗
PubMed1985

Glutaraldehyde-induced changes in the axially projected fine structure of collagen fibrils.

The fine structure of the collagen fibril, as seen in axial projection, is changed by treatment with glutaraldehyde. The changes are detectable in electron-optical staining patterns and in the intensities of the low-angle meridional X-ray diffraction maxima. Current knowledge of the amino acid sequence of collagen and of the axial arrangement of molecules in fibrils permits interpretation in terms of specific alterations to the axial distribution of electron density along the fibril. Analysis of fibril staining patterns from glutaraldehyde-treated calf skin collagen shows that uptake of staining ions in positive staining patterns is inhibited at residues known to interact with glutaraldehyde (lysyl, hydroxylysyl and probably histidyl side-chains) and on other charged residues in the immediate neighbourhood of the glutaraldehyde-reactive residues. This can be seen as a "stain-exclusion effect" due to the presence of bulky polymeric complexes of glutaraldehyde molecules at cross-linking sites. Such stain exclusion accounts for the drastic changes in the negative staining pattern following treatment with glutaraldehyde. The intensity changes observed in the low-angle meridional X-ray reflections from rat tail tendon, similarly treated, also can be explained by the presence of these bulky complexes. Existing data have been used to predict a model of the altered electron density profile indicating the axial distribution of glutaraldehyde along a D-period of moist tendon collagen.

Aldehydes↗
PubMed1985

Cholera in children at Eshowe Hospital.

During a 2-week period in May 1983 Eshowe Hospital inpatients were screened for cholera and positive cases were found on all the wards that were investigated. The high incidence among paediatric patients suggested the possibility of an epidemic in the community and/or cross-infection within the ward. At this time 9 paediatric nurses were found to have cholera-positive stools and subsequently 8 children contracted cholera after admission to hospital. The possibility of cross-infection by person-to-person transmission is suggested. In the second part of this study, our clinical experience of cholera among inpatients during the period January 1983 - March 1984 is reviewed. The number of children in hospital with cholera-positive stools decreased sharply during the winter months; this was possibly related to variations in both temperature and rainfall. The full range of symptomatology was seen and several children had repeated episodes of proven cholera. The mortality was highest in bottlefed babies who were malnourished or under 1 year of age. Between 30 May and 15 June 1983, 293 consecutive children attending the paediatric outpatients department were screened for cholera; 99 cases were confirmed. Thus cholera was shown to be present in the paediatric community outside Eshowe Hospital. Diagnosis based on the history and clinical findings proved unreliable and laboratory investigation was essential. Rivers were the most common and dangerous source of domestic water. The majority of accompanying adults questioned were using untreated water or failing to treat the water adequately.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1985

Mica sandwich technique for preparing macromolecules for rotary shadowing.

The sandwich technique, in which a drop of sample solution is spread into a thin layer between two pieces of freshly cleaved mica, is a simple-to-use alternative to spraying for depositing macromolecules onto mica. Test specimens of collagen molecules and actin filaments were found to suffer less shear-induced damage, they were more uniformly distributed, and only very small sample volumes were needed. Either drying from a glycerol solution (40-70% v/v) or freeze-drying can be employed. Glycerol-drying is simpler, but freeze-drying may offer better preservation of supra-molecular assemblies.

Actins↗
PubMed1985

Immunocytochemical demonstration of glial-neuronal interactions and myelinogenesis in subcultures of rat brain cells.

Subcultures have been established from primary rat brain cell cultures and have been characterised with a range of cell-specific immunocytochemical markers. The subcultures are mainly composed of fibrous astrocytes, oligodendrocytes and neurones. The cells do not divide to any great extent giving a system where it is possible to follow culture development at the cellular level for a number of weeks. During this time oligodendrocytes colonise subpopulations of neurones, differentiate further showing the presence of myelin basic protein and elaborate myelin-like membrane; the fibrous astrocytes remain scattered uniformly throughout the cultures. Radially oriented processes emerge from the oligodendrocyte-neurone aggregates which subsequently coalesce to form fascicles that link the clusters of cells together. These fascicles react with antibodies for both neurofilament protein and myelin basic protein. The subcultures provide a straightforward system that is composed of cells derived entirely from the CNS, is free from mitotic inhibitors and yet retains a sufficiently low cell density to allow immunocytochemical identification of the cell types present. The subcultures should be useful for the study of trophic interactions between oligodendrocytes and neurones as well as the early events associated with myelinogenesis.

Animals↗
PubMed1985

Popliteal artery damage in closed injuries of the knee.

Injury to the popliteal artery is reported in two patients with closed ligament injuries of the knee, and no fracture or dislocation. The importance of careful assessment of the circulation in this type of patient is emphasised.

Adult↗
PubMed1984

Computed tomography of the anterior cruciate ligament.

The anterior cruciate ligaments of 20 patients with suspected pathology in one ligament were studied by thin-section computed tomography (CT) and reformating techniques. In 19 patients, the suspect anterior cruciate ligament was abnormal and this was confirmed by subsequent arthroscopy or arthrotomy in thirteen. Thin-section CT and reformatting techniques provide a useful means of non-invasively imaging the anterior cruciate ligament.

Female↗
PubMed1984

The development of a method for assessing the quality of life of cancer patients.

Although the need for a method of measuring the quality of life of patients undergoing therapy for cancer has been widely recognised, no adequately evaluated or feasible method has been established. We describe a method in which 31 items were assessed by patient self report using linear analogue scales. Eighteen items inquiring about general health problems were derived from the Sickness Impact Profile, an established method of assessing the effect of health upon behaviour and function. Thirteen items inquiring about major problems associated with breast cancer were derived from clinical experience and the opinions of patients with this disease. Each item of the measurement method (instrument) has been evaluated for content, feasibility, reliability and validity by methods that are widely used in psychometry but less familiar in medicine. It appeared easy to use, acceptable and reliable in these assessment. Validity was evaluated indirectly since no standard measurements of quality of life exist for comparison. Most items appeared valid when compared to alternative measurement methods including the Sickness Impact Profile and evaluation by a physician in a structured interview. The correlations between items in the instrument were analysed by factor analysis and seemed to fit with the clinical features of breast cancer. The method distinguished between clinically distinct groups of patients and detected changes with time. The study illustrates the possible approaches to the scientific evaluation of methods for measuring subjective features of patients lives. This method appears suitable for some purposes to measure quality of life in breast cancer and is intended to be flexible enough to be modified for other diseases. However, further evaluation, development and refinement will be needed before routine clinical application can be recommended.

Attitude to Health↗
PubMed1984

Evolution of chromosomal variation in cottontails, genus Sylvilagus (Mammalia: Lagomorpha). II. Sylvilagus audubonii, S. idahoensis, S. nuttallii, and S. palustris.

Chromosomes from cultured fibroblasts of four cottontail species (Sylvilagus audubonii, 2n = 42; S. idahoensis, 2n = 44; S. nuttallii, 2n = 42; and S. palustris, 2n = 38) were analyzed using G- and C-banding techniques. The evolutionary restructuring of the genomes of these species was traced by comparing their banded chromosomes to those of Lepus saxatilis, a species of hare in which the leporid ancestral karyotype is thought to have been conserved. Chromosomal evolution appears to have proceeded primarily through changes in the amount and distribution of heterochromatin and through fixation of Robertsonian fusions. Excluding heterochromatic differences, S. audubonii and S. nuttallii are karyotypically very similar, as are S. aquaticus and S. palustris (previously reported). The genome of the taxonomically controversial species S. idahoensis, compared to other cottontail species, is markedly impoverished in C-band material. These data and those of cottontail species previously described in the literature are incorporated in two alternative phylogenetic schemes.

Animals↗
PubMed1983

Karyotypic conservatism in the genus Lepus (order Lagomorpha).

The G- and C-banded chromosomes of six species of hare (genus Lepus) are presented and compared. No variation in gross chromosome morphology or banding pattern was observed indicating that speciation in this widespread genus has not involved karyotypic change.

Animals↗
PubMed1983

Evolution of chromosomal variation in cottontails, genus Sylvilagus (Mammalia: Lagomorpha): S. aquaticus, S. floridanus, and S. transitionalis.

The banding patterns of mitotic chromosome from three cottontail species, Sylvilagus aquaticus (2n = 38), S. floridanus (2n = 42), and S. transitionalis (2n = 46), are presented and compared with those of the proposed leporid ancestral karyotype, the latter being reflected in a species of hare, Lepus saxatilis (2n = 48). The differences in the diploid numbers of the cottontail species are primarily due to the fixation of Robertsonian fusions which have occurred during the evolution of their respective genomes. Of the eight fusion products identified, seven were species specific, while one, which is thought to reflect their more recent common ancestory, is shared by both S. aquaticus and S. floridanus. Other karyotypic differences include interspecific variation in the amount and distribution of constitutive heterochromatin, as well as the presence of two autosomal pairs in S. transitionalis which do not have apparent banding homologies either with the chromosomes of other cottontails or with those of the Lepus genome. The tendency for certain chromosomes in the ancestral karyotype to show a predisposition to undergo fusion events within the Leporidae is discussed.

Animals↗