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Biomedical subjects

J Pearson

Publications and source records attributed to J Pearson.

At least 109 records · Page 6Linked to original sources
PubMed1994

European semi-anthropomorphic phantom for the cross-calibration of peripheral bone densitometers: assessment of precision accuracy and stability.

A semi-anthropomorphic 'distal radius like' phantom, developed by Kalender and Ruegsegger for use in peripheral bone densitometry using single photon (DPA) dual X-ray (DXA) and quantitative computed tomography (QCT) machines, has been studied with a view to cross-calibrating different types and brands of densitometers in current use. In the context of an EU 'Concerted Action' (second Framework Programme) the phantom was repeatedly measured on six SPA machines, three DXA machines and nine QCT machines (545 measurements). Linear regression equations were derived, individual to each machine, which allowed the derivation of 'standardized densities'. In this way we converted measurements made by machines of the same modality to a common scale of measurements. Two machines (one DXA, one SPA) showed statistically significant instability over time emphasising the need for rigorous quality control in the application of densitometry. In other respects these results provide an encouraging basis for the derivation of standardized normative ranges and the more effective use of peripheral densitometry in future clinical and epidemiological studies.

Absorptiometry, Photon↗
PubMed1994

A longitudinal study of bacterial vaginosis during pregnancy.

OBJECTIVE: To determine the longitudinal changes in the incidence of vaginosis in pregnancy. DESIGN: A prospective study of women during pregnancy. SETTING: A District General Hospital in North-West London. SUBJECTS: Seven hundred and eighteen pregnant women attending antenatal clinics. At their first attendance and subsequently, Gram-stained vaginal smears were examined and Mycoplasma hominis and Gardnerella vaginalis were sought by culture. RESULTS: Initially, 87 (12%) women had bacterial vaginosis diagnosed on Gram-stained reading of the vaginal smears. Examination of further smears, obtained from 176 women at 36 weeks of gestation, showed that those whose vaginal flora was normal initially, and who went to term, rarely developed vaginosis (three of 127, 2.4%). Samples were obtained at 36 weeks gestation from 32 women who had bacterial vaginosis initially, and went to term. In almost 50% (15 of 32) of these a normal lactobacillus-dominated flora had regenerated. Thirty-five women (5%) had initial vaginal smears graded as intermediate. From this group, six of the 17 (35%) women from whom samples were obtained at 36 weeks gestation still had flora of an intermediate pattern; 10(59%) now had normal flora and only one (6%) had developed bacterial vaginosis. Women with bacterial vaginosis were more likely to be culture-positive for M. hominis than those with normal flora (34/78 versus 10/563, odds ratio 42.73 (18.9 to 102.3) P < 0.001), or to be culture-positive for G. vaginalis than those with normal flora (35/78 versus 21/563, odds ratio 21.0 (10.75 to 41.2) P < 0.001). CONCLUSION: Pregnant women do not commonly develop bacterial vaginosis after 16 weeks gestation, and if present, it remits spontaneously in approximately half of those who reach term. As bacterial vaginosis is associated with increased rates of second trimester miscarriage and preterm delivery, any treatment aimed at its eradication in pregnancy should be given no later than the beginning of the second trimester of pregnancy.

Adult↗
PubMed1994

The geometry of the eternal triangle.

Jealousy is often imputed to psychopathology in the protagonist. Psychodynamically, it can be attributed to an ego-deficiency, chronic insecurity, or a deflected libidinal drive. We propose that, when a primary love relationship is threatened, jealousy is best understood from a systems perspective. Three individuals create the experience of jealousy in one of them, which results in a pathogenic "eternal triangle" composed of: the jealous partner who seeks to woo and/or punish an errant mate; the architect of the triangle who takes a lover to supplement the marriage or supplant the mate; and a third person who intrudes across the boundaries of the couple. Therapists must be aware of the role of each agent in order to deal with the volatile, yet highly enduring configuration of the triangle.

Adaptation, Psychological↗
PubMed1994

Chimaerism shown by cytogenetics and DNA polymorphism analysis.

A child with ambiguous genitalia, brought up phenotypically male, had a 46,XX/46,XY karyotype. At laparotomy, he had a left sided ovary and uterus, and a right sided scrotal testis. The 46,XX line made up 50% of cells in the blood and 90% of cells in a skin biopsy. There were no cytogenetic polymorphisms. Analysis of lymphocyte DNA with seven polymorphic DNA markers showed him to be chimaeric, with four, three, and two parental alleles at different loci. He had one paternal and one maternal X chromosome at the marker DXS1053. Based on our data, we would suggest that chimaerism arose as a result of postzygotic fusion of two embryos. We have shown by DNA polymorphisms the presence of autosomal chimaerism in a case of sex chromosome chimaerism, and indicated the usefulness of DNA polymorphisms in determining the origin of chimaerism.

Chimera↗
PubMed1993

The orally active NMDA receptor antagonist CGP 39551 ameliorates the high pressure neurological syndrome in Papio anubis.

The neurophysiological effects of a novel, orally active, competitive N-methyl-D-aspartate (NMDA) receptor antagonist (DL-(E)-2-amino-4-methyl-5-phosphono-3-pentenoic acid ethyl ester), CGP 39551, on the high pressure neurological syndrome (HPNS) were investigated in the non-human primate Papio anubis. Six animals were exposed to maximum pressures of 81 ATA in a helium and oxygen environment, on two occasions. One exposure was pretreated orally with CGP 39551 100 mg/kg 24 h before compression, the other pretreated with an equivalent volume of vehicle, in this case water. CGP 39551 significantly ameliorated the signs of HPNS, compared with controls, at pressures above 31 ATA and prevented the severe signs from occurring at the higher pressures. Onset pressures of the mild signs at low pressures were, however, unaffected. Among EEG changes, the pressure induced reduction in delta wave amplitude was prevented by CGP 39551, but the increase in the amplitude of the 7-9 Hz band was not. It is concluded that CGP 39551 may play an important role in the prophylactic treatment of HPNS.

2-Amino-5-phosphonovalerate↗
PubMed1993

Clinical evaluation of the oesophageal heat exchanger in the prevention of perioperative hypothermia.

We have studied the efficiency of an oesophageal warming device in the prevention of perioperative hypothermia in 22 patients undergoing total hip replacement. Aural canal and skin temperatures (15 sites) were measured before induction of anaesthesia, at the end of surgery and 1 h after recovery and mean body heat was calculated to quantify heat distribution. Core temperature decreased significantly in both groups at the end of surgery, by a mean of 1.8 degrees C in the control group and 1.3 degrees C in the oesophageal heat exchanger (treated) group (P = 0.09). In contrast, mean skin temperature at the end of surgery increased by a median value of 0.26 degrees C in the treated group and decreased by 1.02 degrees C in the control group (P = 0.03). Both groups of patients lost body heat to the same extent (P = 0.34). Thus the oesophageal heat exchanger was ineffective in preventing perioperative hypothermia in a group of patients undergoing total hip replacement.

Adult↗
PubMed1993

A cardiovascular health education program for rural schools.

Public understanding of cardiovascular disease (CVD) risk factors and primary prevention has increased, due in part to community prevention efforts. However, many segments of society are difficult to reach. Such groups still need public education to acquire the knowledge that can lead to behavior change. Community intervention programs in rural areas face the challenge of disseminating health information to widely scattered populations isolated by difficult terrain and weather, and restricted by the sparsity of channels for mass communication. School health promotion programs, because of the special role schools play in rural communities, can help reach rural populations. During a five-year period, the Otsego-Schoharie Healthy Heart Program, a state-funded community intervention program, provided presentations to 18% of the combined total population of two rural counties through its school-based component. It also helped promote other program initiatives by establishing linkages in the community. Schools provide an effective channel for health promotion efforts to reach rural populations.

Adolescent↗
PubMed1993

Eastern equine encephalitis (EEE): a description of the 1989 outbreak, recent epidemiologic trends, and the association of rainfall with EEE occurrence.

An Eastern equine encephalitis (EEE) outbreak in 1989 led to nine human and 196 equine cases, chiefly in coastal Atlantic and Gulf Coast counties. In the past two decades, EEE age-specific incidence and mortality rates have declined compared with earlier years. Analysis of rainfall patterns in areas where human EEE cases occurred between 1983 and 1989 revealed an association between occurrence of human cases and excess rainfall. The association was stronger with data from local weather stations than from statewide rainfall averages and the predictive models were best when applied to northern states. The sensitivity and specificity of these measures varied, depending on the model used, but the positive predictive value was no better than 50%, regardless of the rainfall model applied.

Adolescent↗
PubMed1993

Altered cisplatin and cadmium resistance and cell survival in Chinese hamster ovary cells expressing mouse metallothionein.

Metallothionein (MT) proteins are associated with resistance to the toxic effects of heavy metals, chemotherapeutic drugs, and alkylating agents. It has been suggested that MT may mediate both resistance to toxic agents and cellular metal homeostasis. To study the role of MT, we obtained cells expressing a range of MT levels in the absence of heavy metal induction. We cotransfected the eukaryotic G418 resistance vector pSV2neo and mouse MT-1 cDNA in a pBR322 vector into Chinese hamster ovary cells. Of 200 transfected clonal cell populations, five had constitutive MT expression ranging from 31 to 87 ng of MT/mg of protein. All five populations had increased resistance to cadmium but were less resistant to cisplatin than control cells. On the other hand, the level of foreign MT expression correlated well with the degree of cisplatin resistance among the five clones. Resistance to ionizing radiation and growth rate in the absence of drug or radiation treatment were not affected. However, transfected MT gene expression inhibited the ability of Chinese hamster ovary cells to form colonies in the absence of toxic drug treatment (r = -0.95). The perturbation of cisplatin sensitivity after genetic alteration of MT expression indicates a role for MT in drug resistance: however, the fact that transfected MT gene expression decreased rather than increased drug resistance and decreased plating efficiency in the absence of drug implies that the role of MT may not be one of simply "scavenging" toxic molecules. These data suggest a role for MT in homeostatic cellular processes that, when distributed by transfection of active MT genes, have an effect on cellular drug resistance.

Animals↗
PubMed1993

Human cartilage aggrecan CS1 region contains cryptic T-cell recognition sites.

Cartilage proteoglycan aggregates (PG) are candidate T-cell autoantigens in the pathogenesis of rheumatoid arthritis (RA). We have investigated the possibility that responses to class II-restricted T-cell recognition sites in human cartilage aggrecan (core protein) may depend upon whether these sites are available as free peptide antigens or as part of intact monomers. Analysis of mouse T-cell responses to intact or deglycosylated monomers, purified from human articular cartilage, and to synthetic peptides of the chondroitin sulphate (CS) attachment region homologous repeat sequence showed that recognition of T-cell epitopes in the CS1 region was strongly dependent upon the form of antigen used. The results show that the CS1 region contains cryptic T-cell recognition sites and raise the possibility that fragments of PG, released through the action of extracellular proteases in inflamed joints, may be capable of activating T cells with specificities for epitopes which are not made available following processing of intact PG. T cells with specificities for cryptic epitopes in PG may play a role in the pathogenesis of RA.

Aggrecans↗
PubMed1992

A six year prospective study of fibrinogen and other risk factors associated with mortality in stable claudicants.

A total of 333 patients with stable intermittent claudication at recruitment were followed up for 6 years to determine risk factors associated with subsequent mortality. Cardiovascular diseases were the underlying cause of death in 78% of the 114 patients who died. The strongest independent predictor of death during the follow-up period was the plasma fibrinogen level, an increase of 1 milligram being associated with a nearly two-fold increase in the probability of death within the next 6 years. Age, low ankle/brachial pressure index and a past history of myocardial infarction also increased the probability of death during the study period. The plasma fibrinogen level is a valuable index of those patients with stable intermittent claudication at high risk of early mortality. The results also provide further evidence for the involvement of fibrinogen in the pathogenesis of arterial disease.

Aged↗