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Biomedical subjects

A McDermott

Publications and source records attributed to A McDermott.

17 recordsLinked to original sources
PubMed1992

Expectations of assisted conception for infertility.

OBJECTIVE: To provide reliable prognostic information for couples seeking assisted conception. DESIGN: Analysis of four years' practice (1988-91). SETTING: Private university service linked with NHS reproductive medicine services. PATIENTS: 804 couples with various causes of subfertility, median duration five years, median age of women 34 years. INTERVENTIONS: 1280 completed cycles: 950 in vitro fertilisation, 144 gamete intrafallopian transfer, and 186 intrauterine insemination and superovulation. MAIN OUTCOME MEASURES: Pregnancy and birth rates per cycle and cumulative pregnancy and take home baby rates per couple. RESULTS: In women under 40 years and men with normal sperm, whatever the cause of infertility, results with in vitro fertilisation improved steadily reaching a pregnancy rate per cycle of 30% (95% confidence interval 26% to 35%) during 1990-1 and birth rate per cycle of 29% (23% to 35%) in 1990. Pregnancy and birth rates for gamete intrafallopian transfer were 36% (28% to 44%) and 26% (17% to 37%) and for intrauterine insemination 18% (12% to 24%) and 16% (10% to 22%). After six cycles cumulative probability of pregnancy was 82% and cumulative take home baby rate 70%. Considering only in vitro fertilisation and gamete intrafallopian transfer after four cycles the pregnancy rate was 78% (66% to 91%). CONCLUSIONS: Conception is less likely in women over 40 and men with sperm dysfunction. For other couples the prognosis for a live birth is at least as good as for fertile couples if they persist with treatment.

Adult↗
PubMed1992

Paternal origin of 11p15 duplications in the Beckwith-Wiedemann syndrome. A new case and review of the literature.

A boy suffering from the Beckwith-Wiedemann syndrome (BWS) was found to have partial trisomy of the short arm of chromosome 11 [46,XY,der(5)t(5;11)(p15.2;p14)]. Both his parents were phenotypically normal, but his father carried a balanced translocation between chromosomes 5 and 11 [46,XY,t(5;11)(p15.2;p14)]. DNA analysis of polymorphic markers on 11p15 confirmed the paternal origin of the duplicated material in the child. This case is the sixth report of paternal duplication of 11p15 in BWS. These results are discussed in relation to the possible role of genomic imprinting in BWS and in Wilms' tumor.

Beckwith-Wiedemann Syndrome↗
PubMed1992

A prospective controlled study of in-vitro fertilization, gamete intra-fallopian transfer and intrauterine insemination combined with superovulation.

The relative effectiveness of in-vitro fertilization (IVF), gamete intra-Fallopian transfer (GIFT) and intrauterine insemination (IUI) combined with superovulation in the treatment of infertility were compared in 151 couples undergoing a single cycle of treatment. Treatment was selected as appropriate (IVF for tubal disease, GIFT or IUI/superovulation for nontubal infertility) but possible bias due to non-randomization was overcome by all couples having had favourable fertilization in a previous cycle of IVF. Furthermore, in a preliminary study of initial IVF treatment in 265 couples from whom the study patients were drawn, implantation and pregnancy rates in the diagnostic groups were similar. In the definitive study comparing IVF, GIFT and IUI/superovulation, the pregnancy rate observed with GIFT was highest (40%) but this was not significantly higher than with IVF (28%) or IUI/superovulation (20%). However, the implantation rate per egg transferred by GIFT (21%) was significantly higher than the implantation rate per embryo transferred by IVF (11%). Although the pregnancy rates with GIFT were not statistically greater than with IVF, a significant advantage is likely to be observed in larger groups in view of the better implantation rate. The lower pregnancy rates with IUI superovulation are to be expected because of limited ovarian stimulation, they are nevertheless of comparative interest.

Adult↗
PubMed1991

Determination of membrane protein structure by rotational resonance NMR: bacteriorhodopsin.

Rotationally resonant magnetization exchange, a new nuclear magnetic resonance (NMR) technique for measuring internuclear distances between like spins in solids, was used to determine the distance between the C-8 and C-18 carbons of retinal in two model compounds and in the membrane protein bacteriorhodopsin. Magnetization transfer between inequivalent spins with an isotropic shift separation, delta, is driven by magic angle spinning at a speed omega r that matches the rotational resonance condition delta = n omega r, where n is a small integer. The distances measured in this way for both the 6-s-cis- and 6-s-trans-retinoic acid model compounds agreed well with crystallographically known distances. In bacteriorhodopsin the exchange trajectory between C-8 and C-18 was in good agreement with the internuclear distance for a 6-s-trans configuration [4.2 angstroms (A)] and inconsistent with that for a 6-s-cis configuration (3.1 A). The results illustrate that rotational resonance can be used for structural studies in membrane proteins and in other situations where diffraction and solution NMR techniques yield limited information.

Bacteriorhodopsins↗
PubMed1990

Understanding hospital referral rates: a user's guide.

Detailed referral information from one practice was used to investigate the effect of calculating referral rates in several different ways. Referral rates for individual general practitioners should be related to the number of consultations carried out and not to the number of registered patients; for whole practices list size may be used as the denominator. Most doctors will not need to control for age and sex of patients when comparing referral rates but may need to control for case mix when comparing referral rates to individual specialties. In addition, a method is described for distinguishing systematic variation between the referral rates of individual doctors from the random variation that may arise from data based on fairly small numbers of referrals. The method indicates whether systematic variation is greater than would be expected by chance, and it can be extended to indicate whether variability in referral rates is greater in one specialty than another. Because of random variation with time a year's data may not be sufficient to allow reliable interpretation of referral rates to individual specialties, except for the largest. At present there is no known relation between high or low referral rates and quality of care. Nevertheless, if doctors are to interpret their own rates of referral they need those rates to be reliable and valid. Use of the 10 guidelines described in this paper will help to prevent unwarranted conclusions being drawn from information on general practitioners' rates of referral to hospital.

Adolescent↗
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↗
PubMed1977

Ring chromosome 4.

A mentally and physically retarded boy with a 46,XY,ring (4) (p16q35) chromosome complement is described. Chromosome banding showed that the amount of chromosome material deleted from the ring chromosome 4 was minimal, apparently no more than the telomeres. Chromosomal aberrations appear to be restricted to the production of double-sized dicentric rings, and aneuploidy. The mosiacism resulting from the behavioural peculiarities of ring chromosomes is described as dynamic mosaicism. It is suggested that the clinical features associated with this ring chromosome are more likely to be the result of the effects of a diploid/monosomy 4/polysomy 4 mosaicism than to the deficiency of the telomeric regions of the chromosome.

Child, Preschool↗
PubMedDate not supplied

A patient-based system for describing ambulatory medicine practices using diagnosis clusters.

OBJECTIVE: To develop a patient-based classification system to describe the clinical content of ambulatory medicine practices. DESIGN: A system of 100 diagnosis clusters was developed based on retrospective review of computerized problem lists of patients from a university practice, and then applied to the problem lists of patients in a community practice. Chart review of a 5% random sample (n = 184) of university practice patients who had problem lists was carried out to assess the accuracy of the computerized problem lists. SETTING: A university ambulatory medicine practice and a community ambulatory medicine practice. PATIENTS/PARTICIPANTS: For the same one-year period, all 4,490 patients seen in the university practice and all 1,294 patients seen two or more times in the community practice. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of the 27,634 problems listed for university patients and the 5,648 problems listed for community patients, 22,629 (82%) and 4,924 (87%), respectively, were assigned to diagnosis clusters. For the university and community practices, the mean numbers of problems per patient were 6.1 (SD 5.4) and 4.4 (SD 3.7), and the mean numbers of diagnosis clusters per patient were 4.5 (SD 3.7) and 3.6 (SD 3.0), respectively. Among the ten most common diagnosis clusters in both practices were HYPERTENSION, SYMPTOM OR SIGN, OBESITY, and DIABETES. Only 18% (SD 3%) of patient problem lists in the university practice omitted one or more chronic, important medical problems (e.g., hypertension, dementia, COPD). CONCLUSIONS: This system of diagnosis clusters effectively and efficiently described the clinical content of two types of internal medicine practices, and has important applications in medical education, epidemiology, clinical and health services research, and public policy.

Ambulatory Care↗