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Biomedical subjects

M M Black

Publications and source records attributed to M M Black.

At least 19 recordsLinked to original sources
PubMed1992

Fetal risks in herpes gestationis.

BACKGROUND: The potential risks to the fetus in herpes gestationis have long been a controversial subject, but because of the rarity of the disease, have only occasionally been studied. OBJECTIVE: The purpose of this study was to determine the incidence of fetal complications in herpes gestationis. METHODS: We collected and analyzed the obstetric histories of 74 patients and compared their involved pregnancies with their uninvolved pregnancies. RESULTS: There was an obvious tendency for premature delivery associated with herpes gestations. A slight tendency toward small-for-gestational-age newborns associated with herpes gestationis was confirmed, but, perhaps surprisingly, no increase in spontaneous abortions or stillbirths was noted. The use of systemic steroids did not appear to influence risk. CONCLUSION: Herpes gestationis is associated with an increase in prematurity and small-for-gestational-age infants.

Abortion, Spontaneous↗
PubMed1992

Secondary autoimmune diseases in herpes gestationis (pemphigoid gestationis).

BACKGROUND: Herpes gestationis (HG) is an autoimmune disease of the skin that occurs exclusively in association with pregnancy (or trophoblastic disease). It is associated with the HLA-DR3 and -DR4 antigens that are also associated with several other autoimmune diseases. HG has previously been reported in association with Graves' disease. OBJECTIVE: Our purpose was to determine the frequency of other autoimmune disease(s) in patients with a history of HG. METHODS: Seventy-five patients with a history of HG were studied for the frequency of other autoimmune diseases. RESULTS: We found an increased frequency of Graves' disease in patients with a history of HG. Those with HG have an increased risk for the development of other autoantibodies. There is an increased frequency of autoimmune diseases in the family members of patients with HG. CONCLUSION: Secondary autoimmune disease in HG is unusual, but does occur. The most frequent is Graves' disease.

Autoantibodies↗
PubMed1992

Newly assembled microtubules are concentrated in the proximal and distal regions of growing axons.

We have investigated the sites of microtubule (MT) assembly in neurons during axon growth by taking advantage of the relationship between the proportion of tyrosinated alpha-tubulin (tyr-tubulin) in MTs and their age. Specifically, young (newly assembled) MTs contain more tyr-tubulin than older (more long-lived) MTs. To quantify the relative proportion of tyr-tubulin in MTs, cultured rat sympathetic neurons were permeabilized under conditions that stabilize existing MTs and remove unassembled tubulin. The MTs were then double-stained with antibodies to tyr-tubulin (as a measure of the amount of tyr-tubulin in MTs) and to beta-tubulin (as a measure of total MT mass), using immunofluorescence procedures. Cells were imaged with a cooled charge-coupled device camera and the relative proportion of tyr-tubulin in the MTs was quantified by computing the ratio of the tyr-tubulin fluorescence to the beta-tubulin fluorescence using a novel application of digital image processing and analysis techniques. The amount of tyr-tubulin in the MTs was highest in the cell body and at the growth cone; peak ratios in these two regions were approximately 10-fold higher than for the axon shaft. Moving out from the cell body into the axon, the tyr-tubulin content declined over an average distance of 40 microns to reach a constant low value within the axon shaft and then rose again more distally, over an average distance of 110 microns, to reach a peak at the growth cone (average axon length = 358 microns). These observations indicate that newly assembled MTs are concentrated in the proximal and distal regions of growing axons and therefore that the cell body and growth cone are the most active sites of MT assembly dynamics in neurons that are actively extending axons.

Animals↗
PubMed1992

Isolated basal keratinocytes express pemphigoid gestationis antigen.

Basal keratinocytes were isolated from epidermal cell suspensions prepared by trypsinization of normal human skin. Cells were identified as basal cells by their adherence to collagen and confirmed as basal cells by the presence of pemphigoid antigen. Using an indirect immunofluorescence assay, cells were found to express pemphigoid gestationis-related antigen. Sera from patients with pemphigoid gestationis reacted in one of two immunofluorescence patterns: either polar, in a pattern similar to that observed with bullous pemphigoid serum, or with uniform staining around the cell periphery. Pemphigoid gestationis-related antigen is expressed by isolated basal keratinocytes and is resistant to trypsinization. The heterogeneity of immunofluorescence patterns may correspond to the heterogeneity of antigen recognition by different patients with pemphigoid gestationis.

Antigens↗
PubMed1992

Pemphigoid gestationis--response to chemical oophorectomy with goserelin.

A 46-year-old caucasian female presented in January 1991 with a 17-year history of severe pemphigoid gestationis. She had been on systemic steroids for 10 years since her last pregnancy in 1981 and required doses of 20-80 mg prednisolone daily to control her disease. A chemical oophorectomy was induced using a new luteinizing hormone releasing hormone (LHRH) analogue known as goserelin. A complete remission occurred within 6 months of initiating this treatment and the systemic steroids were discontinued.

Female↗
PubMed1992

Recalcitrant pyoderma gangrenosum--two cases successfully treated with cyclosporin A.

The successful use of cyclosporin A (CSA) in organ transplantation is now well established. In recent years its usefulness has extended to the treatment of cutaneous autoimmune disorders, including pyoderma gangrenosum (P.G.). We report two further cases of recalcitrant P.G., both associated with rheumatoid arthritis (R.A.) which responded to low dose CSA.

Aged↗
PubMed1992

Juvenile colloid milium: clinical, histological and ultrastructural features.

We report the clinical, histological and ultrastructural features of juvenile colloid milium affecting a brother and sister. In this rare condition, translucent papules develop on sun-exposed areas of skin, with onset in childhood. Histologically and ultrastructurally, the papules consist of amyloid-like material derived from epidermal keratonocytes. A review of the literature suggests a possible genetic abnormality that leads to sun-induced degeneration of keratinocytes.

Adolescent↗
PubMed1992

Unusual variants of pemphigoid: from pruritus to pemphigoid nodularis.

We report three patients with pemphigoid nodularis. Patients were females aged 76, 71 and 50 years, and all had features of bullous pemphigoid together with prurigo-like lesions at some stage of their illness. In two cases, nodular lesions preceded the onset of blistering by some months. Blisters arose on normal skin and in one patients also at sites of prurigo lesions. Routine histology of bullous lesions revealed the presence of subepidermal blisters. Electron microscopy performed in two cases confirmed the level of split to be through the lamina lucida. Direct immunofluorescence in all cases was positive, with linear basement membrane zone deposition of IgG and C3. Circulating IgG anti-basement membrane antibody was also detected in all patients, and in two, immunoblotting revealed a single antigen of 220 kD.

Aged↗
PubMed1992

Congenital retinal dystrophies: a study of early cognitive and visual development.

The reported incidence of mental retardation in Leber's congenital amaurosis has varied from 10% to 87%. There has been no review of the estimate since it became possible to delineate an increasing number of diagnostic subcategories. In this study, the visual and cognitive development of 38 children with congenital retinal dystrophies has been followed up prospectively. Children with associated disorders in other systems and those with central nervous system malformations or degenerations were significantly more likely to have learning disability than those without additional medical problems. Most subgroups made little or no visual progress with the exception of the group with associated hypoplasia of the cerebellar vermis. The study highlights the importance of using the specialised techniques now available to delineate fully the visual diagnosis and paediatric perspective because of their relevance to cognitive and visual prognosis.

Child Development↗
PubMed1992

Continuity equation and Gorlin formula compared with directly observed orifice area in native and prosthetic aortic valves.

Orifice areas calculated by the continuity and Gorlin equations have been shown to correlate well in vivo. The continuity equation, however, gives underestimates compared with the Gorlin formula and it is not clear which is the more accurate. Both equations have therefore been tested against maximal orifice area measured by planimetry in eight prepared native aortic valves and four bioprostheses. A computer controlled, ventricular flow simulator (cycled at 70 beats/min) was used at five different stroke volumes that gave cardiac outputs of 2.8 to 7.0 l/min. The mean difference between measured and estimated orifice area was zero for the continuity equation, but -0.14 cm2 for the conventional Gorlin formula. Thus the Gorlin formula tended to give overestimates compared with both measured area and area estimated by the continuity equation, probably because of the effect of pressure recovery. When predictive equations derived from these data were tested, residual standard deviations were around 0.3 cm2 at all stroke volumes for the continuity equation, around 0.2 cm2 for the invasive Gorlin formula, and between 0.2 and 0.4 cm2 for the modified Gorlin formula. These results suggest that estimates of orifice area in an individual valve as judged by any of the equations tested should be seen as a guide to rather than as a precise measure of actual orific area.

Anthropometry↗
PubMed1992

Gangrenous cholecystitis due to hepatitis A infection.

A 6-year-old boy was admitted to hospital with acute gangrenous cholecystitis requiring emergency cholecystectomy. Examination of the gall-bladder revealed severe inflammation with areas of necrosis and mucosal sloughing; serology confirmed hepatitis A infection. Acute cholecystitis due to hepatitis A infection has very rarely been reported.

Acute Disease↗
PubMed1991

Microtubule dynamics in axons and dendrites.

We have investigated the stability, alpha-tubulin composition, and polarity orientation of microtubules (MTs) in the axons and dendrites of cultured sympathetic neurons. MT stability was evaluated in terms of sensitivity to nocodazole, a potent anti-MT drug. Nocodazole sensitivity was assayed by quantifying the loss of MT polymer as a function of time in 2 micrograms/ml of the drug. MTs in the axon and the dendrite exhibit striking similarities in their drug sensitivity. In both types of neurites, the kinetics of MT loss are biphasic, and are consistent with the existence of two types of MT polymer that depolymerize with half-times of MT polymer that depolymerize with half-times of approximately 3.5 min and approximately 130 min. We define the more rapidly depolymerizing polymer as drug-labile and the more slowly depolymerizing polymer as drug-stable. The proportion of MT polymer that is drug-stable is greater in axons (58%) than in dendrites (25%). On the basis of current understanding of the mechanism of action of nocodazole, we suggest that the drug-labile and drug-stable polymer observed in both axons and dendrites correspond to two distinct types of polymer that differ in their relative rates of turnover in vivo. In a previous study, we established that in the axon, these drug-stable and drug-labile types of MT polymer exist in the form of distinct domains on individual MTs, with the labile domain situated at the plus end of the stable domain (Baas and Black, J Cell Biol 111:495-509, 1990). Because of the great difference in drug sensitivity between the drug-labile and drug-stable MT polymer, we were able to dissect them apart by appropriate treatments with nocodazole. This permitted us to evaluate the drug-labile and drug-stable polymer in terms of polarity orientation and relative content of alpha-tubulin variants generated by posttranslational detyrosination or acetylation. In both the axon and the dendrite, the modified as well as unmodified alpha-tubulins are present in both drug-labile and drug-stable polymer, but at different levels. Specifically, the modified forms of alpha-tubulin are enriched in the drug-stable MT polymer compared to the drug-labile MT polymer. In studies on MT polarity orientation, we demonstrate that in axons, MTs are uniformly plus-end-distal, whereas in dendrites, MTs are non uniform in their polarity orientation, with roughly equal levels of the MTs having each orientation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

A three-dimensional analysis of a bioprosthetic heart valve.

A three-dimensional finite element model of the leaflets of a bicuspid bioprosthetic heart valve is presented. The model is based on a non-linear elastic representation of the tissue behaviour which closely simulates that found in experiments. The geometry of the model is based on measurements from a real valve. Shell elements which permit bending have been used in the analysis. The results indicate that bending stresses in the leaflets make a significant contribution to their deformation. This confirms earlier two-dimensional work which had suggested that analyses, where only membrane stresses were modelled, were likely to produce significant errors in the stress states. The analysis also predicts peak stresses close to, but not at, the attachment of the leaflet to the stent post.

Biomechanical Phenomena↗