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Biomedical subjects

J Hewitt

Publications and source records attributed to J Hewitt.

At least 55 records · Page 3Linked to original sources
PubMed1995

Trizygotic quadruplet pregnancy following in-vitro fertilization: an additional factor against replacement of three embryos in young patients?

A study of a 25 year old woman with a previous history of tubal damage, ectopic pregnancy and unsuccessful tubal surgery is reported. Following in-vitro fertilization (IVF) treatment, four viable fetuses were revealed by ultrasound scan at 10 weeks gestation. Two shared the same gestational sac, thus establishing a trizygotic quadruplet pregnancy. The implications of monozygotic twinning in humans are discussed. It is concluded that embryo splitting and its consequences should be seriously considered when multiple embryo transfer in young patients is contemplated.

Adult↗
PubMed1995

Affective reactions to failure as a function of effort and depression.

University students, divided on a quartile split into low (n = 53) and high (n = 42) depression groups (Beck scores of 0-1 or 7 and higher), were presented a series of failure situations in which failure occurred under high effort (with situational factors causing failure) or low effort. Subjects rated their affective reactions to each situation. It was hypothesized that the group low on depression would feel worse after high effort (since this would challenge their sense of self-efficacy) whereas the high depression group would feel better in this condition (since attribution of failure to situational factors would protect their sense of self-esteem). Results were consistent with expectations for the group low on depression. For the group high on depression, the means were rank-ordered as predicted but the difference was not significant.

Depressive Disorder↗
PubMed1995

Sources of variance affecting receipt of aggression.

36 boys and 33 girls from a suburban high school and 24 boys and 22 girls from an inner-city high school rated the frequency with which four other people hit or kicked them during the year. The four people were a brother, sister, non-family male (with whom they fought most during the year), and nonfamily female (with whom they fought most during the year). When responses were dichotomized into "hit" versus "not hit" by a particular person during the year, there was no effect of environment (suburban vs inner-city). The percentage of boys reporting being hit by girls was higher than the percentage of girls reporting being hit by girls. People with siblings were more likely to report being hit by them than by a nonfamily member (although frequency of contact might account for this finding).

Adolescent↗
PubMed1995

The FSHD-linked locus D4F104S1 (p13E-11) on 4q35 has a homologue on 10qter.

Facioscapulohumeral muscular dystrophy (FSHD) has recently been shown to be associated with deletions that are detectable using probe p13E-11 (D4F104S1). Although these deletions reside within large, highly polymorphic restriction fragments (20-300 kb), the "mutant" fragment is usually shorter than 28 kb and can routinely be detected using conventional agarose gel electrophoresis. Yet, the complete visualization of the alleles requires pulsed-field gel electrophoresis (PFGE). Family studies showed that p13E-11 detects two nonallelic loci in this size range, only one of which originates from chromosome 4q35. We have assigned the other p13E-11 locus to chromosome 10qter by linkage analysis in CEPH pedigrees. Knowing the location of both loci improves the diagnostic reliability, as the exact origin of "small" EcoRI fragments can be determined by haplotyping. Since FSHD shows genetic heterogeneity, this 10qter locus became an interesting candidate to be the second FSHD locus. However, analysis of a large chromosome 4-unlinked FSHD family did not provide evidence for linkage on chromosome 10qter.

Chromosome Mapping↗
PubMed1994

Nucleotide sequence of the phosphotransacetylase gene of Escherichia coli strain K12.

The phosphotransacetylase gene (pta) from Escherichia coli strain K-12 1100 was identified in a cloned fragment of chromosomal DNA (Yamamoto-Otake, H., Matsuyama, A. and Nakano, A. (1990) Appl. Microbiol. Biotechnol. 33, 680-682). Overexpression in E. coli confirmed the presence of the pta gene within the cloned fragment. DNA sequence analysis of the cloned pta gene indicates that the predicted phosphotransacetylase polypeptide chain is 713 amino acids in length. The carboxyterminal region of the E. coli phosphotransacetylase shows 42.6% sequence identity with the corresponding enzyme from Methanosarcina thermophila (142 out of 333 residues in corresponding positions are identical). Several short regions of high sequence identity may be structurally or functionally important for enzymic activity.

Amino Acid Sequence↗
PubMed1994

Survival models for developmental genetic data: age of onset of puberty and antisocial behavior in twins.

The use of survival analysis for developmental genetic data is discussed. The main requirements for models based on the decomposition of frailty distributions into shared and unshared components are outlined for the simple case of twins. Extending the earlier work of Clayton, Oakes, and Hougaard, among others, three forms of hazard model are presented, all of which can be applied to pedigree data with flexible baseline hazards without the use of numerical integration. The first two models use an additive decomposition of frailty, with either gamma or positive stable law distributed (PSL) components. The third model previously described by Hougaard involves a multiplicative PSL decomposition. The models are applied to data on the onset of puberty in male twins and illustrate the importance of correct specification of the baseline hazard for correct inference about genetic effects. The difficulty of assessing model specification using information only on the margins is also noted. Overall, the new model with additive PSL components appeared to fit these data best. A second application illustrates the use of a time-varying covariate in examining the impact of puberty on the onset of conduct disorder symptomotology.

Adolescent↗
PubMed1994

A simple method for censored age-of-onset data subject to recall bias: mothers' reports of age of puberty in male twins.

Genetic analysis of variation in age of onset of development milestones or psychopathological behaviors has been little researched, owing largely to the computational difficulty of dealing with "censored" observations. Censored observations arise when the only information on individuals is that they have reached a particular age but without onset having occurred. This paper shows how models can be simply fitted to such data using programs that can perform genetic analysis of categorical data by maximum likelihood. The method is illustrated using the program Mx with data on maternal report of the onset of puberty in twin sons from the Virginia Twin Study of Adolescent Behavioral Development. Frequently, data on age of onset is collected by retrospective recall. This can pose a variety of measurement problems. Suggestions are made for models that account for some of these problems or are robust to their presence. Substantial evidence for "telescoping" of onset dates is found for the puberty data. If left unaccounted for, these effects can artifactually inflate estimates of common environment effects.

Adolescent↗
PubMed1994

Incidence of autoantibodies to GPIIb/IIIa in chronic autoimmune thrombocytopenic purpura may be overestimated by the MAIPA.

Twenty-one serum samples from patients with thrombocytopenia and five from normal individuals were analysed by the MAIPA test to determine specificity of autoantibody reactivity against platelet glycoprotein IIb/IIIa using murine monoclonal antibodies. The sera were also analysed by dot blot to determine their anti-murine IgG activity. Two of the three patient samples positive in the MAIPA test were positive in the dot blot test for anti-murine IgG activity, and on repeating the MAIPA following preabsorption of the serum with mouse ascites proteins they gave negative results. Reactivity of the sample which did not correct by this procedure was shown to be due to an antiHPA1a alloantibody. The potential problem of human heterophile antibodies reacting with mouse antibodies in the MAIPA has been identified and a modification which corrects this has been demonstrated.

Animals↗
PubMed1993

Victim resistance and judgments of victim "consensuality" in rape.

38 participants read about a man who entered a woman's apartment at night, told her that "all he wanted was sex," engaged in the act of sex regardless of what she said or did, and then left. Participants then made a preliminary rating of their agreement or disagreement with the statement. "The woman consented to have sex." To learn how victim's resistance might add or subtract from judgments of victim's "consensuality," participants then read four additional scenarios about how the woman might have responded to the man. Analysis indicated that the absence of any verbal or physical resistance (e.g., "OK--please don't hurt me," or "Please wear a condom--I'm afraid of getting AIDS") increased judgments of victim's consensuality.

Aggression↗
PubMed1993

Gender differences in sexualized perceptions of others.

15 men and 43 women read a scenario in which a woman either agreed to go to a man's dormitory room on the first date or declined his invitation. Participants rated the extent to which each scenario character communicated a desire to have sex to the other. Men were more inclined than women to attribute high sexual interest to the story characters when the woman agreed to go to the man's apartment but not when the woman refused. Contrary to Abbey's conclusion that men see the world in more sexual terms, it was concluded that men will not show this behavior unless they have been primed or at least encouraged by potentially promising female behavior.

Adolescent↗
PubMed1992

Successful treatment of failed AID cases by use of gamete intra-fallopian transfer using donor semen (GIFT (D)).

Over a 13-month period in a newly opened assisted conception unit at the Women's Hospital, Liverpool, gamete intra-fallopian transfer using donor semen, GIFT (D) was offered to eighteen couples who had failed to conceive after numerous cycles of treatment with artificial insemination by donor semen (AID). The indication for the use of donor semen was either azo- or severe oligoaesthenospermia, and, in addition, the female partners have been exhaustively investigated with no major cause found to account for the couple's infertility. Using a basic clomiphene citrate and human menopausal gonadotrophin protocol it was possible to achieve a pregnancy rate of 56% per GIFT (D) cycle. As a consequence of these results it is now our policy to treat couples whose infertility is due to an unresolvable male factor with AID for 12 cycles only. If they have been unsuccessful in achieving a pregnancy after this time, they are offered GIFT (D).

Adult↗
PubMed1992

Toxic epidermal necrolysis treated with cyclosporin.

Toxic epidermal necrolysis (TEN) is a severe life-threatening disorder which has many features in common with graft-versus-host disease. However, immunosuppression with steroids gives disappointing results and is possibly detrimental. We treated two patients who had TEN with a combination of cyclosporin and steroids which resulted in an apparent halt to the evolution of the disease, and a further relapse was aborted using cyclosporin in one of these patients. We feel that the use of this drug in the early treatment of TEN where it is used as a specific therapy aimed at the primary immunopathological events and is used in conjunction with the supportive care patients require, needs to be further evaluated.

Adult↗
PubMed1991

The intra-vaginal culture technique for supernumerary oocytes from gamete intra-Fallopian transfer.

The intra-vaginal culture technique has been utilized for supernumerary oocytes produced as a result of gamete intra-Fallopian transfer therapy. This has enabled knowledge regarding fertilization to be gained and in addition, by adapting the technique to include a transportational element, it has been possible to perform embryo cryopreservation in a separate unit. Analysis of the results of 72 GIFT treatment cycles reveals that when more than four oocytes were collected at laparoscopy, 15/32 (47%) pregnancies were achieved, in comparison with 7/40 pregnancies (17.5%) when four or fewer oocytes were recovered (P less than 0.01). Whilst the GIFT pregnancy rate was higher when spare oocytes were fertilized and embryos cryopreserved (9/16; 56%), six of the 16 patients (37.5%) with failed fertilization of spare oocytes still achieved a GIFT pregnancy.

Adult↗
PubMed1990

Intravaginal culture: present and potential uses.

Over recent years, a simplified method of in-vitro fertilization (IVF), known as intravaginal culture (IVC), has been developed. This article will outline the background to its introduction, provide technical details regarding its practice, review the results achieved to date and explore some of the areas in which this innovation may prove useful in the future.

Female↗