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Biomedical subjects

A McDermott

Publications and source records attributed to A McDermott.

At least 55 records · Page 3Linked to original sources
PubMed1990

The prevention of Down's syndrome in the south western region of England 1975-1985.

Cytogenetic prenatal screening for Down's syndrome in the South West Region of England from 1975 to 1985 was reviewed. The use of amniocentesis increased, and for the years 1981 to 1985 averaged 29.4% of women 35 years or over at their estimated date of delivery. 58 pregnancies were terminated after karyotyping of amniotic fluid cells confirmed trisomy 21. 385,440 live births were born in the region, 452 with Down's syndrome, giving a live birth incidence of 1 in 853. The effective impact of prenatal screening was calculated at an overall 8.3% reduction in Down's syndrome live births, but for the years 1981 to 1985 this rose to 11.3%. In spite of the introduction of new prenatal screening programmes that are not reliant solely on maternal age, it is predicted that substantial numbers of children with Down's syndrome are likely to be born each year. Adequate medical facilities will still be required for the survivors.

Adult↗
PubMed1989

Cloning of Plasmodium yoelii genes expressing three different sporozoite-specific antigens.

Genomic DNA isolated from Plasmodium yoelii (strain #17XNL) was prepared by partial digestion and cloned in Escherichia coli TB-1 with pUC18 plasmid. Antigen-producing recombinants were detected by a battery of monoclonal antibodies against antigens of the sporozoite stages. Four clones producing stage-specific sporozoite antigens were identified. One produced P. yoelii circumsporozoite protein, and three produced other P. yoelii sporozoite antigens.

Animals↗
PubMed1988

Growth hormone, suspected gonadotrophin deficiency, and ring 18 chromosome.

A boy with a ring 18 chromosome karyotype was referred because of short stature; he had growth hormone deficiency and possible hypogonadotrophic hypogonadism. Many children with major chromosomal abnormalities are short, but this case emphasises the need to consider growth hormone deficiency in addition.

Child, Preschool↗
PubMed1986

Bilateral breast carcinoma: prospective evaluation of factors assisting diagnosis.

Bilateral primary breast cancers occur commonly enough to justify adoption of special pre- and post-initial therapy screening. A 13.2% incidence of bilateral breast carcinoma has been found in the breast cancer patients who presented to the Fox Chase Cancer Center with an operatively manageable primary in an arbitrarily defined 30-month period and who have been followed for at least 20 months thereafter. Of the 287 patients seen in those 30 months, 4.5% had synchronously detectable lesions. Xeroradiography is helpful in the initial and follow-up evaluation of the patient for detection of a second primary and may lead to the discovery of an earlier-stage lesion. A history of a family member having a breast cancer was shown to be significant, 26% and 24% for primary and secondary relatives, respectively, and warrant a special screening strategy. Recognition of these factors may lead to earlier detection of curable breast cancers.

Adenocarcinoma↗
PubMed1986

Norethisterone treatment to control timing of the IVF cycle.

The use of norethisterone to control the timing of the preceding menstrual cycle and in consequence the timing of the in-vitro fertilization (IVF) cycle has been evaluated in a therapeutic IVF programme in which oocyte recovery was limited to 2 days each week. A consecutive series of 181 cycles after norethisterone and 29 untreated controls were compared. Menstruation occurred 2-3 days after norethisterone as planned in 82% of patients overall and in 87% of patients whose menstrual cycle length varied by no more than 2 days about the median. Norethisterone treatment did not significantly affect the outcome of IVF treatment compared with the controls in respect to cycles abandoned (12 versus 0%, respectively), peak follicular diameter (mean 18.1 mm versus 18.3 mm 48 h before laparoscopy), oocyte recovery rate (4.6 versus 4.5 per patient), oocyte morphology (63% versus 52% mature), or fertilization rate (72 versus 65% of mature oocytes). Clinical pregnancies were too few for comparison (rates 27 versus 9% per laparoscopy) but the overall rate (23%) indicated effectiveness of the methods. Prior norethisterone treatment appears to be an effective and useful means of controlling the timing of the oocyte recovery in IVF treatment.

Female↗
PubMed1985

Endometriosis and ovulatory disorder: reduced fertilisation in vitro compared with tubal and unexplained infertility.

In-vitro fertilisation (IVF) was carried out once for each of 104 couples who had a single cause of infertility. The group with tubal damage was used as the reference for normal fertilising capacity of both oocytes and sperms: the IVF rates were 68% (71/105) per mature oocyte and 88% (37/42) for couples from whom mature oocytes were recovered. Couples with poor sperm/mucus penetration had reduced IVF rates: 32% (12/38) per oocyte and 60% (9/15) per couple. Sperm function, which was judged normal by means of standard seminal analysis and mucus penetration, was confirmed by normal IVF in unexplained infertility: 63% (37/59) per oocyte and 90% (18/20) per couple. Despite favourable sperm function in their partners, women with endometriosis (without tubal damage) had reduced IVF rates: 33% (19/58) per oocyte and 60% (9/15) per couple. These findings indicate that ovulatory disorder is present in endometriosis and suggest that it causes the associated infertility.

Adult↗
PubMed1985

The prevalence of translocations in parents of children with regular trisomy 21: a possible interchromosomal effect?

It has been suggested that translocations, and perhaps other chromosome rearrangements, disturb meiotic disjunction of uninvolved chromosome pairs and predispose to trisomic offspring. If so, then one would expect an excess of translocations not involving chromosome 21 among the parents of regular trisomic Down's syndrome patients. Such translocations have been reported, but mostly as anecdotal single case reports or very small series. In an attempt to collect a larger series, a collaborative study of regular Down's syndrome families was made in southern England. This was retrospective, and covered periods of 7 to 10 years since 1970. The number of regular trisomy families investigated was 1454. Only 945 of the 2908 parents were karyotyped, and 10 balanced reciprocal translocations not involving chromosome 21 were identified, together with one Robertsonian (13q14q). Expressing these as percentages of the parents tested (945), prevalences are as follows: reciprocals 1.06%, Robertsonians 0.11%, and all translocations 1.16%. Expressed as percentages of the total parents (2908), tested and untested, the prevalences are 0.34%, 0.03%, and 0.37% respectively. The 'true' prevalences, that is what would have been found had all parents been tested, must lie between these two sets of figures. The prevalence of reciprocal translocations exceeds that found for consecutive banded newborn infants, which is 0.16%, and this excess may reflect a real interchromosomal effect. Robertsonian translocations in the banded newborn series are at a frequency of 0.11%, identical to that found in the tested parents of regular trisomics. Interpretation of these figures is critically dependent upon the real prevalence of translocations among the newborn, estimates of which increase as technical methods are improving.

Adult↗
PubMed1984

Human in-vitro fertilisation, in-vivo sperm penetration of cervical mucus, and unexplained infertility.

Oocytes were recovered at routine diagnostic laparoscopy for infertility after stimulation with clomiphene and human chorionic gonadotropin. The results of in-vitro fertilisation (IVF) with the husband's semen were compared in 3 distinct groups of fully investigated infertile couples. Those with bilateral tubal occlusion (36) were combined with fertile controls undergoing sterilisation (6) to form a "tubal" group for normal reference. In this tubal group 48/88 (55%) oocytes were fertilised, at least one oocyte being fertilised in each of 33/42 couples (79%). In couples with a negative or poor postcoital test (PCT), despite mostly normal semen analysis, 8/50 (16%) oocytes were fertilised in 6/21 (29%) couples. In couples with unexplained infertility and a positive PCT, 22/61 (36%) oocytes were fertilised in 17/25 (68%) couples. The results show that spermatozoa unable to penetrate preovulatory cervical mucus are generally also unable to fertilise the human oocyte. They emphasise the biological and prognostic importance of the PCT, and the hidden frequency of defective sperm function as a cause of unexplained infertility. Human IVF is likely to be a more helpful diagnostic investigation than hamster egg penetration testing because it is specific for individual couples. If IVF is to offer therapeutic hope to couples with impaired sperm/mucus penetration the fertilisation rates and the numbers of mature oocytes stimulated for recovery will both have to be high.

Cervix Mucus↗
PubMed1984

Trisomy 5p: a second case occurring in a previously described kindred.

A second child with trisomy 5p has been born in the kindred reported by Brimble-combe et al. The cytogenetic findings were similar to those of the index case except that the derivation was paternal instead of maternal. Improved banding techniques enabled more accurate designation of the breakpoints. The clinical and necropsy findings are described. Three non-specific phenotypic malformations and one brain abnormality, possibly specific, were common to both.

Abnormalities, Multiple↗
PubMed1984

Down's syndrome with a recombinant tandem duplication of chromosome 21 derived from a maternal ring.

An account is given of the cytogenetic investigations of a girl with Down's syndrome found to have a dicentric duplication of chromosome 21. This tandem type of rearrangement was interpreted as a recombinant derived from a single meiotic crossover between a maternal ring 21 and its normal homologue. A population of cells was also found in which breakage of the dicentric resulted in a chromosome 21 with a small terminal deletion. The mother and the proband's younger brother, who was also a ring 21 heterozygote, were both clinically normal.

Adult↗
PubMed1983

Fragile X chromosome: clinical and cytogenetic studies on cases from seven families.

Results of detailed clinical and cytogenetic studies on 13 mentally retarded males and two heterozygous females (one normal and one retarded) are reported. Reference is made to technical modifications to enhance the incidence of expression of the fragile X. The addition of excess methionine to the fibroblast cultures (final concentration of 115 mg/l medium TC 199) was found to be particularly valuable, increasing the incidence of expression up to four-fold, and enabling the demonstration of the fragile X in fibroblasts when it could not be demonstrated in blood cultures in at least one case. Studies on replication patterns of the X chromosomes in the two heterozygous females showed that the fragile X chromosome was genetically active in a significantly greater proportion of cells (74%) in the mentally retarded female, whereas the normal X was active in a similar proportion (72%) in the carrier with normal intelligence.

Adult↗
PubMed1982

Replication status of the fragile X chromosome, fra(X)(q27), in three heterozygous females.

Investigation of lymphocyte cultures from three females heterozygous for fra(X)(q27) shows widely differing proportions of early and late replicating X chromosomes having the fragile site, and suggests that the replication status of the fragile X may be related to the mental capacity of the patient. The study has utilised a sequential staining technique to reduce ascertainment bias, and evidence is presented to suggest that the expression of the fragile site is independent of the differential incorporation of BUdR into the early and late replicating X chromosomes.

Adult↗