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Biomedical subjects

S Meagher

Publications and source records attributed to S Meagher.

30 records · Page 2Linked to original sources
PubMed1995

Invasive prenatal procedures: is 'backup' tissue sampling indicated?

Prenatal karyotyping was performed on 136 patients because of one or more abnormalities detected on ultrasound. A total of 188 specimens was obtained which included fetal blood, amniotic fluid and chorionic villus. In 52 patients a second or 'backup' sample was obtained and in 100% cytogenetic analysis was successful. In contrast, failure to obtain a result occurred in 4 (4.7%) of the remaining 84 patients where a second sample was not obtained. In the event of primary sample failure, backup sampling not only improves the karyotype yield, but obviates the need for a second pass procedure with its attendant risks.

Amniotic Fluid↗
PubMed1994

Chromosomal abnormalities detected after an abnormal ultrasound in pregnancy.

Improvements in ultrasound technology have resulted in an increasing number of requests for prenatal chromosome testing because of fetal abnormalities detected in utero. Between January 1990--January 1991, 388 tissue samples were referred to our laboratory for cytogenetic analysis, of which 202 were amniotic fluids samples, 157 chorionic villus biopsies and 29 fetal blood specimens. Of these 54 were referred for fetal abnormalities detected prenatally on high resolution ultrasound. Chromosomal analysis was successful in 50 cases, and included 6 (12%) chromosomally abnormal fetuses: 2 trisomy 21, 2 trisomy 18, one 45,X and one unbalanced translocation. The maternal age for three of the four cases of autosomal trisomy were below 35 years (the cut-off for amniocentesis for advanced maternal age). In contrast, 273 prenatal chromosome studies performed for advanced maternal age (AMA) produced only 4 (1.5%) chromosomally abnormal fetuses. These abnormalities detected on ultrasound indicate a significant population of fetal chromosomal aberrations which would otherwise not be detected prenatally.

Adult↗
PubMed1993

Resuscitating fresh stillbirths.

Guidelines for duration of resuscitation of freshly-stillborn term infants and their long term outcome are unclear. The predictive factors of both cerebral palsy and early neonatal demise include Apgar scores of 3 or less at 10 minutes, perinatal acidaemia and neonatal seizures. We describe the case of severe perinatal asphyxia (umbilical artery pH at birth of 6.75, Apgar scores of 0.1 and 5 0.1 5 at 1.5 and 10 minutes and neonatal hypertonia) in a term pregnancy, where the infant made an uneventful recovery and was discharged home well. Guidelines for neonatal resuscitation are discussed.

Abruptio Placentae↗
PubMed1991

Edwards' syndrome after the replacement of cryopreserved-thawed embryos.

A case of Edwards' syndrome after the replacement of frozen-thawed embryos is reported. The presence of cardiac abnormalities and limb deformities raised the suspicion of chromosomal abnormality. The diagnosis of trisomy 18 was made by cytogenetic analysis of fetal blood from the umbilical vein. The chromosomal nondisjunction might have been spontaneous or because of freezing and thawing. If it occurred as a result of freezing and thawing, it is more likely that this was at the first cleavage division rather than the second meiotic division because the embryos were frozen at the late pronuclear stage. Unfortunately, there were no karyotypic markers in the couple's chromosomes to time the nondisjunction. The wisdom of using donor oocytes in an ovum donation program from patients with long-standing infertility is questioned.

Abnormalities, Multiple↗
PubMed1991

Gamma interferon suppresses acute and chronic Trypanosoma cruzi infection in cyclosporin-treated mice.

To determine if exogenous gamma interferon is effective in immunosuppressed mice infected with Trypanosoma cruzi, recombinant murine gamma interferon was administered to cyclosporin-treated mice with either acute or chronic T. cruzi infection. Gamma interferon significantly decreased parasitemia and prevented death in acutely infected mice. Parasitemias and mortality of mice treated with both gamma interferon and cyclosporin were similar to those of immunocompetent controls. In chronically infected mice, cyclosporin treatment produced significantly more organ explant cultures positive for T. cruzi. Fewer positive cultures, particularly for spleen and heart, were obtained from cyclosporin-treated mice when they also received gamma interferon. Ketoconazole treatment of mice resulted in no positive cultures. Cyclosporin treatment did not prevent activation of peritoneal macrophages by parenteral gamma interferon, nor did it have a consistent effect on serum titers of alpha/beta or gamma interferon in response to a second challenge inoculum of T. cruzi. These data indicate that exogenous gamma interferon suppresses acute and chronic T. cruzi infection in cyclosporin-treated mice but that gamma interferon is not as effective as the relatively specific antimicrobial ketoconazole. Gamma interferon activates macrophages despite cyclosporin treatment, and its effects appear to be tissue specific.

Acute Disease↗
PubMed1989

Trypanosoma cruzi: explant organ cultures from mice with chronic Chagas' disease.

Explants of 13 different organs obtained from C3H/HEN, Swiss-Webster, and C57Bl/6 mice chronically infected with Trypanosoma cruzi (Y strain) were cocultivated with mouse embryo fibroblasts to determine the organs that contain T. cruzi during the chronic infection. Explant cultures frequently yielded T. cruzi as late as 12 months after infection. Spleen and skeletal muscle were most frequently positive; heart cultures were rarely positive in any mouse strain. C3H/HEN mice had significantly more cultures positive than Swiss-Webster mice, as expected from relative susceptibility of C3H/HEN mice to acute infection. In contrast, C57Bl/6 mice, relatively resistant to acute infection, had significantly more cultures positive at 12 months of infection than Swiss-Webster mice. Also, C57Bl/6 mice had a significant increase in the number of positive cultures at 12 months of infection compared to 6 months of infection. These results show that organisms can be recovered routinely from some tissues during the chronic infection, that murine susceptibility to infection should differentiate between acute and chronic infection, and that C57Bl/6 mice may lose control of infection during the chronic infection.

Acute Disease↗
PubMed1989

Vein-to-artery grafts: the long-term development of neo-intimal hyperplasia and its relationship to vasa vasorum and sympathetic innervation.

A series of 14 vein-to-artery grafts, 1 mm in diameter and 5 mm long, were inserted microsurgically into iliac arteries of rats. They were analysed histologically 8-18 months later and compared with control iliac arteries in the same rats. Neo-intimal hyperplasia developed and was measured in all grafts but the values did not significantly exceed the equivalent intimal plus medial thicknesses of control arteries. Vasa vasorum developed and were quantitated as the number of vessels per mm2 of neo-intima, but also did not differ significantly from control values. The density of sympathetic innervation was quantitated using fluorescent catecholamines. There was an overall significant increase in the long-term graft innervation compared with control arteries. These results show that such small vein grafts adapt and function very effectively, in a manner remarkably similar to the artery they replace, for long periods of time.

Adrenergic Fibers↗
PubMed1987

Vein to artery grafts: a study of re-innervation in relation to neo-intimal hyperplasia.

This study was undertaken to determine whether there is an association between the sympathetic re-innervation and development of neo-intimal smooth muscle hyperplasia in vein to artery grafts. Iliolumbar vein to iliac artery grafts were placed in 21 rats by microsurgical techniques. Graft innervation and neo-intimal thickness were examined at five time intervals between 1 and 32 weeks after grafting. Nerve fibres were demonstrated microscopically by formaldehyde-induced fluorescence of catecholamines. The degree of innervation was quantitated by counting the nerve profiles and this was compared with the amount of neo-intimal hyperplasia. The distance between adventitial nerve profiles and neo-intima ('diffusion' distance) was measured to determine whether there was a trophic interaction between the two. These data were compared with similar measurements in control iliac arteries in the same animals. Although the development of both graft innervation and neo-intimal hyperplasia occurred coincidentally, no definite quantitative association between the two was established.

Adrenergic Fibers↗
PubMed1984

Vein to artery grafts. An experimental study of reinnervation of the graft wall.

Iliolumbar vein to iliac artery grafts were placed in 21 rats by microsurgical techniques. Graft innervation was examined at five time intervals between 1 and 32 weeks after surgery. Nerve fibers were demonstrated microscopically by formaldehyde-induced fluorescence of catecholamines. The morphology and degree of graft innervation were assessed, semiquantitatively, relative to the contralateral iliac artery (control) within each animal. Nerves were seen in the graft region as early as 2 weeks, but it was not until 4 weeks that they were present along its length (5 mm). The formation of a nerve plexus in the adventitia surrounding the graft was evident at 8 weeks. By 16 weeks the degree of innervation in the graft had increased to a level that was greater than the control iliac artery in three of four animals examined. Grafts at 32 weeks were also hyperinnervated. However, the morphology of this innervation was different from the control arteries; nerve fibers were finer, not varicosed, and were located at a greater distance from the outer layer of smooth muscle cells. The origin of the nerves appeared to be collateral sprouts from nerves supplying the adjacent iliac vein and also from invading vasa vasorum. The host iliac artery nerve plexus did not contribute to graft innervation.

Animals↗