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Biomedical subjects

M G Wilson

Publications and source records attributed to M G Wilson.

At least 55 records · Page 3Linked to original sources
PubMed1989

Chromosome mosaicism in 6,000 amniocenteses.

Multiple cell-multiple flask mosaicism was found in 0.20% of 6,000 amniocenteses, and multiple cell-single flask mosaicism was found in 0.92%. Multiple cell-multiple flask mosaicism usually was found in fetal or infant tissues at delivery or elective abortion. Most multiple cell-multiple flask mosaicism involved sex chromosomes and was either 45, X/46, XY or 45, X/46, XX. Except for one fetus with 45, X/46, XX and an aortic coarctation, phenotypic abnormalities associated with sex chromosome mosaicism were not found in these patients. One normal boy has continued to show 45,X mosaicism during the first 4 years of life. Autosome abnormalities found in multiple cell-multiple flask mosaicism included del(18q) associated with fetal anomalies. Apparently normal phenotypes were associated with prenatal trisomy 17, two de novo supernumerary marker chromosomes, and monosomy 21. Since an aberrant cell line present in only one primary amniotic fluid cell culture was occasionally identified from another amniocentesis or at birth, multiple cell-single flask mosaicism involving a sex chromosome or a viable autosome abnormality cannot be assumed to be an in vitro event. Maternal cell contamination, which was found in 0.49% of amniocenteses, could have resulted in an erroneous diagnosis of fetal sex in two cases if cells from independent culture vessels were not examined.

Amniocentesis↗
PubMed1989

Reimplantation of infected total hip arthroplasties in the absence of antibiotic cement.

Twenty-two patients with deep infection of the hip were reimplanted and followed for a minimum of 3 years. All reimplantations were done without antibiotic-impregnated cement. Nine were done using cemented and 13 using cementless components. Two patients had recurrent infection. Both of these had primary Pseudomonas infections and had cemented revisions. At 3 or more years, 91% of patients are infection-free as determined by clinical evaluation, erythrocyte sedimentation rate, and, in a few, aspiration. Cemented hips had less pain than cementless hips, although both had equivalent functional scores. The significance of these findings is that reimplantation of infected hips can be successfully accomplished without antibiotic-impregnated cement. Cementless fixation can therefore be used. Clinical results with cementless hips for reimplantation will improve with current designs and techniques.

Aged↗
PubMed1989

Variation in the normalized tetanic force of single frog muscle fibres.

1. The forces produced in maximal fixed-end tetani of single fibres isolated from the anterior tibialis muscle of the frog Rana temporaria have been measured at sarcomere lengths of 2.2 microns and temperatures near 0 and 10 degrees C. 2. When normalized by either cross-sectional area or dry weight per unit length at a sarcomere length of 2.2 microns, the forces vary over a twofold range. 3. The normalized force is not significantly correlated with the velocity of unloaded shortening or the twitch characteristics of the fibres. Lack of variability of these two quantities (together with histochemical evidence) suggest that only one fibre type is present in the experimental sample. 4. The steady rate of energy liberation (stable, heart rate) of the fibres during isometric tetani is positively correlated with the normalized force, indicating that extra ATP splitting is required to produce higher forces. 5. Fibres with a higher ratio of dry weight per unit length to cross-sectional area ('dry density') show a higher force when normalized by area, but not when normalized by dry weight per unit length. 6. Fibres with a more circular cross-sectional profile produce more force when normalized by either cross-sectional area or dry weight per unit length. The significance of this correlation is unclear. 7. The contribution of various sources to the total overall variation in normalized force is assessed. It is suggested that a diffusible substance or substances may be involved in modulating fibre force.

Adenosine Triphosphatases↗
PubMed1989

Isometric force production before and after chemical skinning in isolated muscle fibres of the frog Rana temporaria.

1. The force produced in single fibres isolated from the anterior tibialis muscle of the frog Rana temporaria has been measured in tetani near 4 degrees C, and then in calcium-activated contractures of segments of the same fibres after chemical demembranation. All measurements were made at a sarcomere length of 2.3 microns. Force was normalized for fibre cross-section by the dry weight per unit length of the segments, which is proportional to cross-sectional area (Elzinga, Howarth, Rall, Wilson & Woledge, 1989). 2. The ratio of the force developed by the skinned segments to that produced by the intact fibres was inversely related to segment cross-section (dry weight per unit length), falling from approximately 1.0 for the thinnest segments to 0.6 for the thickest segments. 3. It is calculated that the accumulation of orthophosphate ion within contracting segments can account for a significant part of the decline in relative force in thicker segments. 4. The absolute forces in intact fibres and their derived segments were strongly correlated, but normalization by segment cross-section removed the correlation. 5. It is concluded that the sources of the approximately twofold variation in normalized force in both intact and skinned preparations are different. The existence of diffusible, force-modulating factors in intact fibres, which may be removed during skinning, is considered.

Animals↗
PubMed1989

Sister chromatid exchanges in the human active and inactive X chromosomes.

Four human female fibroblast strains with an i(Xq) or derivative X chromosome as a cytological marker for the inactive X chromosome were used to determine the frequency of sister chromatid exchanges (SCEs) in the active and inactive X chromosomes. No significant difference in SCE frequency between the active and inactive X chromosomes was observed. Therefore, the state of chromatin condensation and the late DNA replication in the facultative heterochromatin of the inactive X chromosome do not appear to influence the SCE frequency.

Cells, Cultured↗
PubMed1989

The fate of acetabular allografts after bipolar revision arthroplasty of the hip. A radiographic review.

We reviewed the radiographs of thirty-one patients (thirty-two hips) who had had revision of the acetabular component of a total hip arthroplasty with a bipolar socket supplemented by allograft and were followed for twenty-four to forty-eight months. The grafts were categorized according to their consistency (solid or crushed bone), the location of the acetabular defect (peripheral [rim] or central), and the extent of the acetabular defect (contained--the medial part of the acetabular wall was intact, or non-contained--it was deficient). We recorded the time to incorporation of the graft, the amount of migration of the socket in the superior and medial axes, and the percentage of graft remaining at the time of the most recent follow-up. The time to healing was similar for all categories of grafts. The central, contained, solid grafts had less resorption than did the central, contained, crushed-bone grafts, as evidenced by less migration of the socket during follow-up. The non-contained grafts, in both peripheral and central locations, were associated with high rates of migration and of instability of the socket.

Acetabulum↗
PubMed1988

DA/DAPI-fluorescent heteromorphism of human Y chromosome.

Variation of DA/DAPI intensity in the Yq12 band was observed in five amniotic cell specimens and one blood specimen from the father of one fetus. Three distinct classes of Yq heterochromatin were identified by distamycin A (DA) treatment of the cell cultures and various staining techniques. The heterochromatin in the Yq11.23 sub-band does not undercondense when exposed to DA, and shows pale fluorescence with quinacrine staining, positive C-banding, and bright fluorescence with DA/DAPI technique. This class of heterochromatin was consistently observed in all specimens studied. The other two classes of heterochromatin are in the Yq12 band. Both show undercondensation when exposed to DA, quinacrine-bright fluorescence, and positive C-banding; however, one class of heterochromatin shows DA/DAPI-bright fluorescence and the other shows pale fluorescence. The size and banding intensity of the two classes of heterochromatin in Yq12 are variable. These results provide cytological evidence of heterogeneity within the Y heterochromatin region containing AT-rich DNA.

Chromosome Banding↗
PubMed1988

The energetics of work and heat production by single muscle fibres from the frog.

During active shortening the heat rate in isolated muscle fibres is greater than during isometric contraction, and increases with velocity of shortening (V), but at a decreasing rate as the maximum velocity (V0) is approached. For shortening at V less than 0.25 V0 the amount of extra heat produced during a period of shortening is proportional to the distance shortened, but for rapid shortening (V greater than 0.5 V0) the extra heat increases less than proportionally with the distance shortened. After a period of shortening the higher heat rate returns to the isometric level over a period of several hundred milliseconds. A similar period of increased heat rate is seen after a quick release. After shortening 10% of muscles slack length at 0.1 V0 the amount of heat produced during tension redevelopment is similar to that after a quick release. But after more rapid shortening there is less heat production than after a quick release.

Adenosine Triphosphate↗
PubMed1987

New autosomal dominant branchio-oculo-facial syndrome.

We observed an autosomal dominant disorder of abnormal upper lip, which resembles a poorly repaired cleft lip, malformed nose with broad bridge and flattened tip, lacrimal duct obstruction, malformed ears, and branchial cleft sinuses and/or linear skin lesions behind the ears in several persons in 3 families. In each of the 3 families, an affected parent had at least one affected child. Father-to-son transmission in one of these families ruled out X-linked inheritance. Other anomalies include coloboma, microphthalmia, auricular pits, lip pits, highly arched plate, dental anomalies, and subcutaneous cysts of the scalp. Premature graying of hair occurred in the affected adults. Growth retardation, developmental delay, and hand anomalies are variable components of the syndrome.

Abnormalities, Multiple↗
PubMed1987

Expression of fragile X in human-mouse somatic cell hybrids.

Fragile X expression was studied in human-mouse cell hybrids prepared from lymphocytes and fibroblasts obtained from a mentally retarded male. The patient showed a fragile X in 29-35.5% of his lymphocytes in medium 199 (M199) and in M199 plus fluorodeoxyuridine (FdU). One lymphocyte hybrid clone showed no expression in M199 and low expression in M199 + FdU. The other lymphocyte hybrid clone showed significantly increased expression in both media, comparable to levels in the parental cells. Fibroblast cultures from the patient showed no fragile X expression in M199 and 17% expression in M199 + FdU. Fragile X expression was also found in fibroblast hybrid clones in M199 and was significantly enhanced by the addition of FdU. Fragile X expression in one clone was consistently lower than in the other two clones and in the parental fibroblasts. Our results indicate that the level of fragile X expression varies in the hybrid clones, since frequencies similar to those of parental cells and suppressed frequencies were found. The presence or absence of a specific human chromosome did not correlate with the level of fragile X expression.

Animals↗
PubMed1987

Effect of C-banded heterochromatin on centromere separation.

The present study is to determine the effects of centromeric heterochromatin on centromere separation. Amniotic cell cultures in which the centromeric heterochromatin of one chromosome was at least twice as large (qh+) as the heterochromatin (qh) in the homologous chromosome were selected. Fifteen amniotic cell samples with 1qh+, 9qh+ or 16qh+ were studied. The size of the centromeric heterochromatin was directly correlated with the delay in centromere separation. The chromosome with the smaller centromeric heterochromatin tended to show earlier centromere separation than the homologue with the larger heterochromatin. Our results suggest that the quantity of centromeric heterochromatin may influence the genetic control of centromere separation.

Amnion↗
PubMed1986

Absolute values of myothermic measurements on single muscle fibres from frog.

The heat and force produced in tetanic contraction of single fibres from anterior tibialis muscle of the frog Rana temporaria have been observed at measured temperatures close to 1 and 10 degrees C. Heat was measured using a Hill-Downing type thermopile. In control experiments with a resistor of known heat capacity comparable to a single muscle fibre, it was found that Peltier and Joule heating produced identical thermopile outputs. The Peltier method was used to introduce a known amount of heat into the system in each experiment with a muscle fibre. From the response to this heating the heat capacity of each preparation was obtained and used to calculate the absolute amount of heat production from the thermopile output. The heat produced during tetanic contraction (H) could be described by Aubert's equation [H = Ha (1 - e-t/tau) + hbt]. In some fibres there was no labile heat (Ha), whereas in others it was clearly present. The stable heat rate (hb) was strongly temperature dependent (Q10 = 4.06). At 0 degree C the stable heat rate (normalized by dry weight) in the single fibres was significantly greater than that in whole anterior tibialis muscle.

Animals↗
PubMed1985

Reduction of fragile X expression in blood after cryopreservation.

Frequency of fragile X expression was investigated before and after cryopreservation (-196 degrees C) in the blood of 4 affected males, 3 fragile X carriers and in a fibroblast cell strain from a fragile X male fetus. The results indicate that there is a significant decrease (p less than 0.05) in the frequency of the fragile X expression in lymphocytes after cryopreservation, as compared to the fresh blood, but not in fibroblasts. This suggests that cryopreserved blood specimens may not be suitable for fragile X analysis.

Female↗