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Biomedical subjects

J M Bird

Publications and source records attributed to J M Bird.

28 records · Page 2Linked to original sources
PubMed1990

Cytogenetics of porcine sperm chromosomes following IVF of zona-free hamster oocytes.

Porcine sperm chromosome karyotypes were obtained from two boars following heterologous in vitro fertilization (IVF) of zona-free hamster ova with ionophore-capacitated porcine spermatozoa. The karyotype yield per inseminated ovum was 9.3% (n = 1658), and there was no significant deviation from the expected 1:1 sex ratio (p greater than 0.5). Cytogenetic analysis revealed hyperhaploid (2.5%) and hypohaploid spermatozoa (1.9%). Spermatozoa with structural chromosome aberrations constituted 7.1% of the analyzed karyotypes, and these were predominantly chromosomal breaks, although acentric fragments were also found (2.6%).

Animals↗
PubMed1989

Molitity and acrosomal changes in ionophore-treated bovine spermatozoa and their relationship with in vitro penetration of zone-free hamster oocytes.

Frozen-thawed spermatozoa from Friesian bulls held at stud in Ireland were used to assess the effect of ionophore on motility, acrosome reaction and heterologous in vitro fertilization. Bovine spermatozoa penetrated zone-free hamster oocytes following treatment with calcium ionophore in the absence of bovine serum albumin (BSA) and in the presence of 10 mM caffeine. Sperm velocity was stimulated in concentrations of caffeine <2.5 mM following dilution with medium containing BSA. Sperm attachment to the plasmalemma showed no association with penetration rates of zona-free hamster oocytes. Penetrated oocytes in regimens with >0.1 mM ionophore did not progress through Meiosis II. Increasing concentrations of ionophore induced the acrosome reaction more rapidly, although this was associated with reduced motility. Hyperactive motility was observed in calcium ionophore-treated spermatozoa which were capable of penetrating zona-free hamster oocytes. Sperm velocity remained unchanged. whereas the track:vector ratio, a measurement of curvilinear movement, was reduced. This work may have important implications for the assessment of bovine fertility and cytogenetic analysis of bovine sperm.

Journal Article↗
PubMed1986

Computed tomography in the elderly: changes over time in a normal population.

The clinical, psychometric, and computed tomographic (CT) status of previously fit elderly volunteers is described at follow-up for up to four years. A number of relationships were found between psychometric and CT scores, but a dementing group could not be determined on the basis of a single scan. However, a subtle reduction in cognition over time was significantly related to CT changes, and occurred in 10%. Larger ventricles were also found in a small sub-group, who developed late-onset depressive disorders; recent bereavement was related to ventricular size. Thus a single CT scan may not be a useful discriminatory test in early dementia, but a repeat demonstrating ventricular enlargement, is likely to be significant. In the elderly, cognitive and CT scan deterioration should not be expected unless a disease process is occurring; this may be indicated by subtle cognitive impairment or by late-onset depressive disorder.

Aged↗
PubMed1985

Computed tomographic brain studies and treatment response in schizophrenia.

Ventricular enlargement has been described in chronic schizophrenia since 1927. The CT Scan has stimulated considerable interest and studies have shown that 50% of chronic schizophrenics and up to 20% of acute schizophrenics have enlarged ventricles. Widening of cortical sulci, cerebellar atrophy, third ventricular enlargement and reversed hemispheric asymmetry have also been reported. Ventricular enlargement seems to both predate the development of psychosis and to develop further during the course of the illness. Twin studies indicate that ventricular enlargement may be the result both of genetic vulnerability and of environmental onslaught. The other abnormalities may be secondary. Schizophrenics without ventricular enlargement show disturbances of a range of Dopamine-related variables. Schizophrenics with ventricular enlargement show some evidence of serotonin and noradrenaline cell loss. Very few published papers address the issue of treatment response. These seem to demonstrate a relationship between enlargement and poor response to neuroleptic medication. Schizophrenics with very large ventricles may also be particularly sensitive to the adverse effects of neuroleptics. It is not yet clear that the CT Scan may be used to identify patients unlikely to respond to medication. Long term prospective studies are required.

Atrophy↗
PubMed1984

Oligosaccharides containing fucose linked alpha(1-3) and alpha(1-4) to N-acetylglucosamine cause decompaction of mouse morulae.

Two- to four-cell and eight-cell mouse embryos were incubated in various fucosylated and unfucosylated oligosaccharides, fucose binding protein, and fucosylated BSA. Compaction at the eight-cell stage was reversed by a mixture containing the oligosaccharides lacto-N-fucopentaose II (80-90%), in which fucose is linked alpha(1-4) to N-acetylglucosamine, and lacto-N-fucopentaose III (10-20%), in which fucose is linked alpha(1-3) to N-acetylglucosamine. Pure lacto-N-fucopentaose III (LNFP III) and 3-fucosyl lactose (containing fucose alpha(1-3)glucose) had a similar effect. All three molecules affected blastocyst formation. Various closely related fucosylated and unfucosylated oligosaccharides did not induce decompaction or inhibit blastocyst formation. The proportion of embryos incubated from the two- to four-cell stage in LNFP II/III which reached the eight-cell stage and formed blastocysts was reduced. Those which formed compact morulae subsequently decompacted. Precompact or early compacting eight-cell embryos incubated in LNFP II/III compacted normally but subsequently decompacted and failed to form blastocysts. Decompaction of eight-cell embryos in LNFP II/III occurred during a specific period of development (80-90 hr post-hCG) and was reversible up to 84-86 hr post-hCG, but not by 92 hr post-hCG. The period of sensitivity to LNFP II/III was associated with the decrease in the ability of calcium-free medium to cause decompaction. It appears that LNFP II/III interferes with a later calcium-independent phase of compaction and we propose that LNFP III and II inhibit an endogenous lectin-saccharide interaction between membranes involved in the stabilization of compaction.

Acetylglucosamine↗
PubMed1982

Nucleic acid synthesis in microsporocytes of Lilium cv. cinnabar: events in the nucleus.

In an electron microscopic autoradiographic study of DNA and RNA synthesis during meiosis isolated Lilium microsporocytes were supplied with [3H]thymidine and [3H]uridine. DNA synthesis occurred in the nucleus during the zygotene and pachytene intervals of meiotic prophase. Most of the activity was associated with the chromatin, but some synthesis early in zygotene was located at the nucleolus. RNA synthesis occurred throughout prophase until diplotene, when all activity ceased until after division. The newly synthesized RNA was found mostly in association with the chromosomal peripheries or in the space between chromosomes. There was also a peak of [3H]uridine incorporation at the nucleolus, which followed shortly after the synthesis of DNA at that site. The localization of DNA and RNA synthesis at the various stages of meiosis is discussed in relation to current concepts of chromosome pairing, crossing-over, ribosomal DNA amplification and cycles of RNA metabolism.

Autoradiography↗
PubMed1981

Computed tomography and the outcome of affective disorder: a follow-up study of elderly patients.

Forty-one subjects from an earlier study, who had undergone computed tomography (CT) during their in-patient care for affective disorder, were followed up clinically for a minimum of one year. Mortality at two years was also determined, and comparisons made with 50 age-matched controls. Those with affective disorder showed a higher mortality than controls, but the difference just failed to reach significance. Within the affective group, however, mortality was significantly higher in patients who had previously shown ventricular enlargement on CT, confirming our earlier suggestion that these patients might have constituted a distinct subgroup. Failure of the affective group to improve performance on a simple cognitive test at follow-up was related to persisting depression. These and other findings are discussed.

Aged↗
PubMedDate not supplied

Effects of electropermeabilization on the association of foreign DNA with pig sperm.

This study was conducted to evaluate the effects of an electric pulse (electroporation/electropermeabilization) on the binding of foreign DNA molecules to porcine spermatozoa. We previously examined various parameters involved in the association of foreign DNA with sperm after a simple incubation procedure and now report the effects of electroporation on this association. Using end-labeled and random primer labeled lambda HindIII DNA fragments (23-0.125 kb), it was demonstrated that the DNA fragments interacted with the sperm after electroporation. These samples were then centrifuged and washed extensively to establish if any of the labeled DNA was associated with the spermatozoa. It was determined that approximately 10(8) molecules of DNA were associated with 1.5 x 10(7) mL-1 motile spermatozoa after five medium washes. After each wash, samples were withdrawn for gel analysis and scintillation counting. Gel analysis followed by autoradiography revealed the distinctive band pattern of lambda HindIII DNA associating with sperm. In situ visualization studies with biotin-labeled DNA revealed that approximately 75% of motile sperm carried DNA bound to the post-acrosomal region. However, the intensity of the binding varied, with some sperm being more strongly stained than others. Using [3H]dCTP-labeled DNA followed by light microscope autoradiography, approximately 70% of the sperm were strongly stained in the post-acrosomal region. There was a 5-10% increase in the amount of DNA bound by sperm when the samples were electroporated.

Animals↗