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Biomedical subjects

S M Hall

Publications and source records attributed to S M Hall.

At least 145 records · Page 8Linked to original sources
PubMed1988

Peripheral pulmonary vascular and airway abnormalities in adolescents with rheumatic mitral stenosis.

Lung biopsy specimens were taken from 15 adolescents (aged 11-21 years), at the time a mitral valvotomy was performed. In addition to quantitative light microscopic studies three specimens were also examined by scanning and transmission electron microscopy. In all cases, the pulmonary vascular abnormalities were most marked in the capillary bed and in the vessels immediately proximal and distal to it. The capillaries showed a marked increase in basement membrane material at the blood/gas barrier, and were embedded in dense connective tissue within the alveolar walls. Intra-acinar and, to a lesser extent, pre- and post-acinar vessels showed an increase in muscularity, severe circumferential intimal fibrosis, and abnormally thick and dense adventitial connective tissue. The peripheral airways were encased in dense connective tissue, which appeared to compress them. Bronchial smooth muscle was increased. Six months after the mitral valvotomy was performed, the mean pulmonary arterial pressure had fallen from 42 mm Hg to 23 mm Hg. Despite this satisfactory haemodynamic result, the long-term effects of small airway compression on the growing lung indicate the need for early relief of mitral valve obstruction, possibly made easier by the new technique of balloon angioplasty.

Adolescent↗
PubMed1988

Preadmission antipyretics in Reye's syndrome.

The parents of 106 children who had had Reye's syndrome and those of 185 comparison children who had febrile illnesses were interviewed in order to compare preadmission medication exposure rates in the two groups. Although comparable proportions of case and comparison patients had taken antipyretics in the three weeks before admission, a significant excess of cases (59% compared with 26% in the comparisons) had been given aspirin, whereas significantly more comparison children (49% compared with 25% in the cases) had taken paracetamol. There was an excess exposure to aspirin in children under 5 years of age; the excess observed in older patients just failed to reach significance. Separate analyses within Northern Ireland and England also showed a case-comparison difference. A significant correlation was shown between aspirin (but not paracetamol) exposure and the closeness with which cases conformed to the diagnostic criteria of Reye's syndrome, measured by an artibrary score. The many difficulties of conducting and interpreting the findings of an epidemiological risk factor study of an association between aspirin and Reye's syndrome are reviewed and emphasised. Inherent biases were present in this as in previous studies and it did not conform to the classical case-control design. Nevertheless the findings suggested that an association between Reye's syndrome and preadmission aspirin may exist in some children.

Acetaminophen↗
PubMed1988

Brucella abortus-specific immunoglobulin in isotypes in serum and vaginal mucus from cattle vaccinated with strain 19 and challenge exposed with virulent strain 2308.

The immunoglobulins (IgG1, IgG2, IgM, and IgA) of the Brucella-specific antibody response of 69 crossbred beef heifers were studied after Brucella abortus strain 19 vaccination and strain 2308 challenge exposure. The immunoglobulin isotype responses in serum and vaginal mucus were measured by use of fluorescent immunoassay. Serum antibody responses were detected also by 3 standard serologic tests (complement fixation [CF], Rivanol precipitation, and the CARD test] and 2 primary bindings assays that detect IgG antibodies. One month after vaccination, mean antibody titers for all immunoglobulin isotypes were higher for vaccinated cattle (n = 46) than for nonvaccinated controls (n = 23). After vaccination, IgA antibody responses in vaccinated cattle were only 2-fold higher than those for controls, whereas IgG1, IgG2, and IgM antibody responses were 3- to 90-fold greater than those for controls. Measurement of IgA antibody responses classified 21 of 39 vaccinates as seropositive after vaccination, whereas the other isotypes classified 28 or 34 cattle as seropositive. Three months after challenge exposure, the mean antibody responses for each isotype were higher in cattle that aborted or were culture positive than in cattle that did not abort and were culture negative. Although IgG1, IgG2, and IgM antibody titers were each of benefit in identifying B abortus-infected cattle, it did not appear that the magnitude of the antibody responses provided sufficient discrimination between S19-vaccinated cattle and S2308 challenge-exposed cattle. Serum IgA antibody responses were 10-fold higher after challenge exposure than after vaccination and may be a response to mucosal infection with the virulent organism.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Thinning of fetal pulmonary arterial wall and postnatal remodelling: ultrastructural studies on the respiratory unit arteries of the pig.

Adaptation to extra-uterine life and postnatal remodelling of intra-acinar arteries was followed in 34 Large White pigs, from birth to adult life, applying morphometry to light and electronmicroscopic studies. After birth, percentage wall thickness decreased rapidly due to a reduction in overlap of adjacent smooth muscle cells and an increase in smooth muscle cell surface area/volume ratio, (p less than 0.01 at 12 h), without a reduction in the volume density of smooth muscle cells. Smooth muscle cells appeared immature at birth and synthetic rather than contractile organelles predominated. Between 3 weeks and 6 months myofilament volume density doubled (p less than 0.0001). At all ages, pericytes, intermediate and smooth muscle cells showed similar volume densities of contractile and synthetic organelles. Thus, the high fetal pulmonary vascular resistance appeared to be due to the shape and arrangement of smooth muscle and other contractile cells within the vessel wall, rather than an excessive contractility of these cells. After birth rapid remodelling of arterial wall structure achieved a reduction in wall thickness by 30 min, continuing during the first week of life. After 3 weeks, remodelling involved an increase in wall thickness, connective tissue deposition with more collagen than elastin (p less than 0.0001), and smooth muscle cell differentiation.

Animals↗
PubMed1987

The response of regenerating peripheral neurites to a grafted optic nerve.

Optic nerves, both viable (fresh or pre-degenerate) or non-viable (frozen-thawed) were grafted between the proximal and distal stumps of freshly transected sciatic nerves, using either 10/0 sutures or strips of nitrocellulose paper. The majority of regenerating peripheral neurites, always in association with Schwann cells, avoided the viable optic nerve grafts, growing along the outside of the grafts in well vascularized minifascicles until they gained the distal stumps. A very small number of axons entered the grafts and grew, for distances typically less than 2 mm, between layers of astrocyte processes. The number of axons entering was not increased by using predegenerate grafts or by blocking Schwann cell proliferation in the proximal stumps by pre-treating the latter with mitomycin C. There was no evidence of a continuous cellular-acellular partition between graft and host during the outgrowth phase of the neurites: it was concluded that axons failed to enter the grafts as a result of inhibitory interactions between Schwann cells and astrocytes. When grafts were rendered acellular, all structured debris, including recognizable components of the extracellular matrix, was rapidly removed and the space thus vacated was invaded by manifascicles of Schwann cells and regenerating neurites. Glial fibrillary acidic protein-positive astrocytes and carbonic anhydrase II-positive oligodendrocytes persisted within viable grafts for 17 months; they did not migrate into the surrounding nerve.

Animals↗
PubMed1987

Vaccination of cattle with chemically modified and unmodified salt-extractable proteins from Brucella abortus.

Beef heifers were vaccinated on Day 0 with either salt-extractable protein (CSP) or chemically modified CSP (dCSP) from Brucella abortus Strain 19 in Freund's complete adjuvant (FCA). Six weeks later, vaccination was repeated, and heifers received either the homologous or heterologous vaccine. Another group of heifers received only FCA and saline. Vaccinations with CSP or dCSP stimulated marked antibody responses to B. abortus, as detected by standard serologic tests, an enzyme-linked immunosorbent assay, or a quantitative fluorometric immunoassay. Twelve percent of the heifers were seropositive by the CARD test 1 year after vaccination. Vaccination stimulated an increased cell-mediated immune response as measured by lymphocyte blast transformation (LBT) to B. abortus antigens. Fifty-six weeks after the initial vaccination, the heifers were challenged intraconjunctivally with 1.9 X 10(7) colony-forming units of B. abortus strain 2308. Sixty to 83% of the heifers aborted in each group and 70-83% of the heifers were culture positive. There were no significant differences (P greater than 0.05) among groups with respect to the number of abortions or the number of culture-positive heifers. Antibody responses increased rapidly within 4 weeks after challenge. Overall, antibody responses were greater for heifers that aborted than for those that did not abort. These differences were significant (P less than 0.05) only as measured by the fluorometric procedure. The LBT responses appeared to be higher for vaccinates than for the control group, but these differences were not significant (P greater than 0.20). There was a significantly lower (P less than 0.05) LBT response to heat-killed B. abortus in those heifers that aborted compared to those that did not.

Abortion, Veterinary↗
PubMed1987

Conducting pulmonary arteries: structural adaptation to extrauterine life in the pig.

A quantitative light microscopical and ultrastructural study of the elastic and large muscular pulmonary arteries of 30 Large White pigs aged from birth to 6 months yielded light microscopical measurements on 120 arteries and 62,560 ultrastructural assessments, which composed a computerised database. After birth mean arterial medial thickness and mean smooth muscle cell diameter decreased during the first 4 days (p less than 0.01). Mean interlamellar distance decreased, reaching its nadir at 1-3 weeks (p less than 0.01). All these features increased between 3 weeks and adulthood (p less than 0.01). In the smooth muscle cells synthetic rather than contractile organelles were dominant during the first 3 weeks. Between 3 weeks and adulthood, however, smooth muscle cell myofilament volume density increased (p less than 0.0001). At all ages the smooth muscle cells of the outer lamellar units of elastic arteries had a greater myofilament volume density than those of adluminal units (p less than 0.0001). The amount of connective tissue increased between 3 weeks and adulthood, collagen and basement membrane increasing preferentially (p less than 0.0001, p less than 0.05, respectively). Thus the conducting pulmonary arteries, like the peripheral resistance arteries, adapt structurally to extrauterine life. Remodelling occurred rapidly after birth, and then gradually during growth, as connective tissue was deposited and smooth muscle cells matured.

Adaptation, Physiological↗
PubMed1987

Comparison of TRACK XI fluorometric immunoassay system with other serologic tests for detection of serum antibody to Brucella abortus in cattle.

The TRACK XI system (TRACK) is a commercially available fluorometric immunoassay system that has been adapted for the detection of antibodies to several antigens in various animal species. Serum antibodies to Brucella abortus were detected by TRACK and compared with those obtained from two primary binding assays (a fluorometric immunoassay [FIAX] and an enzyme-linked immunosorbent assay) and three standard serological tests (complement fixation, Rivanol precipitation, and CARD tests). A total of 298 serum samples were tested by each serological test. Of these serum samples, 134 were negative controls, 43 were from cattle 1 month after vaccination with B. abortus 19, and 121 were from cattle 10 to 12 weeks after a midgestational, intraconjunctival challenge with B. abortus 2308. The results of this study indicated that TRACK is both reproducible and accurate. The results compared favorably with those of other serological methods. TRACK is more rapid than either the enzyme-linked immunosorbent assay or FIAX system. TRACK was the most sensitive (96.3%) test, with a specificity of 100%.

Animals↗
PubMed1986

Normal adaptation of pulmonary arterial intima to extrauterine life in the pig: ultrastructural studies.

Adaptation of the pulmonary arterial intima was studied in injected lung specimens of 34 Large White pigs. Each type of pre- and intra-acinar artery was studied separately using transmission and scanning electron microscopy. Determination of the endothelial surface/volume ratio and volume densities of (1) endothelium and subendothelium, (2) endothelial cytoplasmic organelles and (3) subendothelial connective tissue elements yielded 6832 measurements which comprised a computerized database. At birth, endothelial cell morphology changed more rapidly and to a greater extent in peripheral than in proximal arteries. Endothelial surface/volume ratio increased (p less than 0.0001). Fetal surface projections, junctional interdigitations and overlap became less evident. Adaptational changes were complete in three weeks. Between three weeks and adulthood a reduction in endothelial surface/volume ratio suggested cell growth. In the subendothelium the volume density of collagen and basement membrane and elastin increased (p less than 0.001). The internal elastic lamina, immature in all arteries at birth increased in thickness and integrity until in the adult, only in small muscular arteries did gaps between elastin profiles ensure frequent contact between endothelial and smooth muscle cells. At all ages regional differences in endothelial cell morphology were evident.

Adaptation, Physiological↗
PubMed1986

Occlusion of intra-acinar pulmonary arteries in pulmonary hypertensive congenital heart disease.

Lung biopsy specimens from 10 consecutive cases of congenital heart disease and pulmonary hypertension (2 months-6.5 years) were examined by light and electron microscopy. By light microscopy, 8 cases showed a reduction in number of patent alveolar wall arteries associated with the structural features of early pulmonary vascular disease-extension of muscle, a significant increase in pulmonary arterial medial thickness (P less than 0.001) and little if any intimal proliferation (Heath & Edwards Grade I or II). In one additional child with Grade IV disease, arterial number could not be determined accurately. For all 10 cases, all blocks of tissue examined by light and electronmicroscopy showed absence of any lumen in structures identified as alveolar wall arteries by their position, shape and the presence of an external (or single) elastic lamina. In 3 additional similar cases, endothelial cells of narrowed and occluded arteries were marked by labelling with the lectin Ulex europaeus. Occluded arteries were identified consisting of mature smooth muscle cells and remnants of degenerating endothelial cells. Occlusion of alveolar wall arteries appears to be an early event in the development of pulmonary vascular disease, is associated with differentiation of smooth muscle cells in normally thin walled precapillary arteries and precedes significant obliterative intimal changes in more proximal vessels.

Arterial Occlusive Diseases↗
PubMed1986

Enzyme-linked immunosorbent assay for detection of serum antibodies to Pasteurella haemolytica cytotoxin (leukotoxin) in cattle.

An enzyme-linked immunosorbent assay (ELISA) was developed for detection of bovine serum antibodies to the cytotoxin (leukotoxin) of Pasteurella haemolytica. A partially purified, cytotoxic, and immunogenic protein obtained from supernatants of logarithmic-phase P. haemolytica was used as the ELISA antigen. Preadsorption of sera with various cytotoxic, somatic, and capsular antigen preparations demonstrated that the assay was specific for anticytotoxin antibodies. ELISA anticytotoxin titers had a strong, significant correlation to cytotoxin-neutralizing-antibody titers. The ELISA, however, was more rapid and allowed for greater numbers of samples to be run than did the neutralization technique. ELISA anticytotoxin titers were high in cattle vaccinated with a live P. haemolytica vaccine, whereas unvaccinated cattle and cattle receiving a P. haemolytica bacterin had low ELISA anticytotoxin titers. A significant positive correlation between ELISA titers and resistance to experimental bovine pneumonic pasteurellosis was present.

Animals↗