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Biomedical subjects

R A Beatty

Publications and source records attributed to R A Beatty.

At least 19 recordsLinked to original sources
PubMed1987

Sciatica and epidural gas.

Epidural gas in the patient with sciatica can sometimes provide a clue that there is a surgically treatable lesion. Our patient had the sudden onset of sciatica at night, which was relieved by walking. An intraspinal synovial cyst was associated with epidural gas.

Aged↗
PubMed1985

Myxomatous degeneration of the lumbar intervertebral disc.

Sixteen patients were operated on for lumbar pain and pain radiating into the sciatic nerve distribution. In all 16, when the anulus fibrosus was incised, soft, gray disc material extruded under pressure like toothpaste being squeezed from a tube. This syndrome of myxomatous degeneration is a distinct entity, different from classical fibrotic disc degeneration or herniated nucleus pulposus. Surgical removal associated with partial facetectomy produced excellent results. The concept of incompetence of the anulus fibrosis is discussed.

Adult↗
PubMed1985

Vocal cord paralysis associated with anterior cervical fusion: considerations for prevention and treatment.

In a series of 375 patients with anterior cervical fusions, long-term follow-up results complete with laryngeal examination were obtained in 102 patients. One patient was found to have an inferior laryngeal nerve palsy, and one had a superior laryngeal nerve palsy. Both deficits were thought to be the result of surgical trauma. Measures to minimize the incidence of vocal cord paralysis include careful surgical technique and knowledge of the surgical anatomy of the laryngeal nerves. Suggestions are given for the assessment of postoperative hoarseness, and for the management of vocal cord paralysis.

Cervical Vertebrae↗
PubMed1978

Problems in estimating non-disjunction rate from the F-bodies of two-headed human spermatozoa.

The F-bodies of two-headed human spermatozoa offer a unique potential for estimating non-disjunction rate of the Y chromosome. But there is an unexplained quantitative discrepancy: a gross deficiency of two-headed spermatozoa with no F-bodies, relative to the numbers with one F-body in each head. Any estimation of non-disjunction rate would be overshadowed by this and other major factors. Two-headed spermatozoa cannot be regarded as a random aggregation of haploid heads in pairs. DNA measurements confirmed that each head of 25 normal-sized two-headed spermatozoa was haploid. The distribution of F-body classes is independent of whether sperm tails are single or double. Donors with an exceptionally high incidence of two-headed spermatozoa exist.

Genetics, Medical↗
PubMed1977

F-bodies as Y chromosome markers in mature human sperm heads: a quantitative approach.

It is generally accepted that at least some Y chromosomes in human mature sperm heads are represented in preparations by fluorescent F-bodies. From data consisting solely of F-body scorings and the visually estimated size of sperm heads from normal donors, a quantitative model is developed which permits simultaneous estimation of six parameters representing biological factors (the proportions of ploidy classes and of their sex-chromosome complements) and biassing factors (not all Y chromosomes represented by F-bodies, not all F-bodies representing Y chromosomes, and error in scoring ploidy from visual size). The analysis is statistically adequate and succeeds in predicting a variety of independently validated phenomena. The work may be regarded as a contribution to the integration of qualitative and quantitative evidence in the study of F-bodies. In all, 21,700 one-headed spermatozoa from 12 donors were scored. A mean of 54% spermatozoa lacking F-bodies was subject to a standard deviation between donors of 4.8, over and above binomial error. Analysis yielded the following estimates: 83.3% of diploid spermatozoa are XY, the remainder XX and YY in assumed equal number (this information assists analysis of the origin of embryonic triploidy); 2.4% of spermatozoa are diploid (this estimate does not compete in accuracy with direct estimates from DNA absorbance); only 83% of Y chromosomes are represented by F-bodies; 7% of haploid heads and 14% of diploids contain one or more "adventitious bodies" indistinguishable from true F-bodies. The visually scored head sizes "Small" and "Medium" correspond approximately with haploidy and diploidy; nearly all haploids are scored as Small, and 72% of the Medium are diploid. F-bodies are not thought at present to give a useful basis for estimating the presumably low incidence of sex-chromosome aneuploidy and nondisjunction. No such estimate has been attempted. The problem is overshadowed by not fully understood complicating factors of greater magnitude, which now appear to be a major subject of enquiry. Some implications and possible future developments are discussed.

Humans↗
PubMed1975

A quantitative study of the second meiotic metaphase in male mice (Mus musculus).

Over 11,000 second meiotic metaphase spreads stained for the pericentromeric region have been studied quantitatively in male mice of 14 strains. The sex-chromosome constitution of a cell could be judged objectively if X and Y chromosomes and ploidy were all scored. A bias arose if only Y chromosomes and ploidy were scored but could be corrected statistically. There was no sign of other forms of bias. The original contiguity of X and Y second metaphases in vivo was very occasionally evident in the preparations. Most of the subhaploid aneuploid counts were assumed to be artifactual. The incidence of truly aneuploid second metaphases in 13 strains was estimated as 0.38+/-0.12%. The estimated average rate per chromosome was 0.019+/-0.006%, with a comparable order of magnitude for the sex chromosomes alone. Simultaneous aneuploidy of two or more chromosomes of the haploid set was estimated to be very rare. Of the spreads from 13 strains, 9.6% were polyploid (2N, 3N, 4N) and showed most of the possible combinations of sex chromosomes. Nearly all the polyploid spreads were considered to arise by artifactual cell fusion at the time of second metaphase during the preparative technique, especially of the X and Y daughter-cell products of the first meiotic division. Other modes of origin (true polyploidy, accidental superposition of cells during preparation) were unlikely. The data could be accommodated by a statistical model with only four parameters. It allowed for artifactual fusion mainly between daughter cells but also between non-daughter cells, bias in one scoring method, and bias in the numbers of cells with given ploidy successfully mounted. Current techniques of chromosome preparation were thought to be wholly unsuitable for the recognition of true polyploidy. The artifactual origin of polyploid spreads was borne out by an absence of polyploid spermatozoa in 14 strains. There appeared to be a virtually constant transmission rate of paternal X and Y chromosomes from early meiosis to late blastocyst. The estimated rate of 49.05+/-0.67% with a Y chromosome also estimated the primary sex ratio. There was evidence of polymorphism in autosomal pericentromeric staining in 3 strains. No measure of the numbers of autosomes or sex chromosomes varied significantly between duplicate preparations or between duplicate males of a strain.

Aneuploidy↗
PubMed1975

The recognition and incidence of haploid and polyploid spermatozoa in man, rabbit and mouse.

The existence of polyploid mammalian spermatozoa has been inferred from studies of Feulgen-DNA absorption. Rabbit spermatozoa fell into two discrete groups with mean absorptions close to a 1:2 ratio (inferred to be haploids and diploids respectively); simple visual appraisal of the size of the head or nucleus gave an identical classification. The incidences of ploidy classes were 98-94% haploid, 1-06% diploid, 0-00% higher than diploid (N = 3010; from DNA measurements and visual appraisal of the size in a rabbit chosen to have a high incidence of diploids) and, correspondingly, 99-691%, 0-308%, 0-001% (N = 138001; from sixty-nine unselected rabbits, scored by visual appraisal of the size of the sperm head). In man also, virtually discrete groups with absorptions close to a 1:2 ratio existed and were inferred to be haploids and diploids respectively. A few human spermatozoa were found with absorptions corresponding to a ploidy of three and/or four. Visual appraisal of the size of the human sperm nucleus as Small, Medium or Large was only a partial guide to ploidy. All Small human spermatozoa measured for DNA absorption were found to be haploid. About two-thirds of Medium human spermatozoa were found, however, to be haploid, and some Large spermatozoa were haploid or diploid. The incidences of ploidy classes in the human were 99-37% haploid, 0-56% diploid, 0-07% higher than diploid (N = 5554; with consistency between duplicate slides and between two subjects; from DNA measurements and visual appraisal of nuclear size). The estimated incidence of diploid human spermatozoa is consistent with the known incidence oftriploid fetuses. In a mouse with a putatively high incidence of diploids, all 1000 DNA measurements were nevertheless within the haploid range, with one diploid encountered outside the main sampling.

Animals↗