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Biomedical subjects

R Smith

Publications and source records attributed to R Smith.

At least 649 records · Page 36Linked to original sources
PubMed1995

Spread of maternal HIV infection in Scotland from 1990 to 1992.

In Scotland since January 1990, unlinked anonymous testing of Guthrie cards has documented maternal HIV-1 antibody in neonatal blood. District postcode and quarter year of birth determined prevalence and spread of infection. The Fujirebio particle agglutination assay screened for HIV-1 antibody, with confirmation by ELISA and full western blotting. Births to known HIV infected women were reported to the Royal College of Obstetricians and Gynaecologists. 0.3/1000 childbearing women were infected with HIV-1 with no significant increase from 1990 to 1992. Spread of infection from 11 to 26 districts has occurred. In 1990, 74%(14/19) of HIV positive deliveries were known to obstetricians falling to 33%(7/21) in 1992. Spread of HIV-1 infection has occurred to mothers who live outside closely defined areas and who do not belong to recognised high risk groups. In Scotland, two thirds of mothers and their infants will not receive early prophylactic care for their HIV disease.

AIDS Serodiagnosis↗
PubMed1995

Disordered water homeostasis in schizophrenia and cerebral ventricular size.

BACKGROUND: A possible association between disordered water homeostasis and cerebral ventricular size in patients with schizophrenia was investigated. METHOD: In a cross-sectional study of hospitalised patients, cerebral ventricular size was measured in 16 schizophrenic patients with disordered water homeostasis and 16 matched schizophrenic controls by magnetic resonance imaging. RESULTS: Ventricle to brain ratio, third ventricular index, bicaudate index and bifrontal index tended to be greater in those with schizophrenia with disordered water homeostasis, although differences were significant only for the bifrontal index (P < 0.05). Strong negative correlations were found between ventricular size and performance on neuropsychological testing in the disordered water homeostasis group. CONCLUSION: These results provide evidence for an association between structural brain abnormality and disordered water homeostasis in a subset of schizophrenic patients.

Cerebral Ventricles↗
PubMed1995

Corticotropin-releasing hormone-induced vasodilatation in the human fetal-placental circulation: involvement of the nitric oxide-cyclic guanosine 3',5'-monophosphate-mediated pathway.

This study has used an in vitro perfusion method to investigate the mechanism by which CRH causes vasodilatation in the human fetal-placental circulation. In normal term placentas, vasodilatory responses to human CRH (24-7000 pmol/L) were examined during submaximal vasoconstriction (100-120 mm Hg) of the fetal-placental vasculature induced by prostaglandin F2 alpha (0.7-2 mumol/L), KCl (50-100 mmol/L), or the thromboxane A2 mimetic, U46619 (0.05-0.5 mumol/L). Infusion of CRH caused a concentration-dependent vasodilatation that was similar in the presence of each constrictor agent (P > 0.05). The CRH antagonist, alpha-helical CRH-(9-41) (200 pmol/L), and a polyclonal CRH antiserum significantly inhibited CRH-induced vasodilatation during constriction with prostaglandin F2 alpha (P < 0.05). Vasodilatory responses to CRH were attenuated by the nitric oxide synthase inhibitor, N omega-nitro-L-arginine (100 mumol/L; P < 0.05), and the guanylate cyclase inhibitor, LY 83583 (1 mumol/L; P < 0.05), but not by the cyclooxygenase inhibitor, indomethacin (3 mumol/L; P > 0.05). In placentas of women with increased fetal vascular resistance, as demonstrated by Doppler ultrasound waveforms in vivo, CRH-induced vasodilatation was significantly reduced (P < 0.05). These results indicate that in the human fetal-placental circulation, CRH causes a vasodilatory response via a nitric oxide-/cGMP-dependent pathway. CRH may play a role in the control of vascular resistance to blood flow in the normal human placenta, and there may be a deficiency in the CRH signaling pathway of placentas with increased fetal vascular resistance.

Adult↗
PubMed1995

Identification and characterization of a corticotrophin-releasing hormone receptor in human placenta.

Corticotrophin-releasing hormone (CRH) causes vasodilatation in the human fetal-placental circulation and has paracrine actions in placental tissue, suggesting that CRH receptors may be present in the human placenta. We have now identified and characterized placental CRH binding sites and compared them to those described previously in human myometrium and rat pituitary. Radiolabelled ovine CRH binding to placental membranes was pH-, time-, temperature- and divalent cation-dependent and was reversible in the presence of 1 mumol/l unlabelled ovine CRH. Scatchard analysis of placentae delivered vaginally or by elective caesarean section revealed dissociation constants (Kd) of 214.5 +/- 84 pmol/l (N = 8) and 45.4 +/- 23.9 pmol/l (N = 9), respectively. The Kd for caesarean placental binding sites was similar to that of human myometrium (59.6 pmol/l, N = 3) and rat pituitary (82.5 pmol/l, N = 3) receptors. However, in vaginally delivered placentae the CRH binding sites had a much lower affinity (p < 0.05). The receptor densities (Bmax) of vaginally delivered and caesarean-delivered placentae were 28.6 +/- 9.6 and 6.1 +/- 2.8 fmol/mg, respectively (p < 0.05). Chemical cross-linking studies using disuccinimidyl suberate indicated that the molecular weight of the CRH receptor in the placenta and rat pituitary is 75 kD. We conclude that there is a high-affinity population of CRH binding sites in the human placenta that are physicochemically similar to pituitary and myometrial CRH receptors. The CRH receptor properties in the placenta change in response to labour, when CRH levels in maternal blood are highest, suggesting that placental CRH may regulate its receptor.

Adolescent↗
PubMed1995

A proposal for a national mammography database: content, purpose, and value.

A national mammography database is a centralized, computerized method of data collection consisting of two possible parts: a national mammography audit and a system for monitoring and tracking patients. A national mammography audit refers to collecting and analyzing medical audit data of individual mammography practices at a national level and is a critical step in improving the interpretive component of mammography. The monitoring and tracking component refers to a centralized system that provides women and physicians with a recruitment and follow-up mechanism to optimize participation in mammography services. Both parts of a national mammography database represent important components in the improvement of mammography quality. However, unique scientific, legal, and fiscal concerns are important to consider before establishing a national mammography database.

Female↗
PubMed1995

Difficulties experienced in implementing the ABR travelling wave velocity (Delta V) technique with two commercially available systems.

The ABR Delta V technique involves measuring the difference in latency of the wave V click-evoked ABR in the presence of ipsilateral high-pass noise filtered at 1.42 kHz and at 5.68 kHz. It has been reported that a small latency difference between the two conditions is suggestive of Ménière's disease. The aim of this study was to establish normative data for two commercially available systems. The latency differences obtained in the present study are considerably smaller than those previously reported in the literature. Other problems, including difficulty in identifying wave V in the masked conditions, prevent us from currently using this test technique. There are a number of technical problems which may account for some of the problems experienced when implementing the Delta V technique with commercial equipment and there is at least the possibility that the problems may be overcome in the future.

Adult↗
PubMed1995

Transgendered ... and taken to jail.

1. Gender identity disorders have the essential feature of incongruence between assigned sex, that is, the sex that is recorded on the birth certificate, and gender identity. 2. The majority of transsexuals are males who consider themselves to have feminine gender identity and regard their genitalia and masculine features with repugnance. 3. Intersexuality occurs when gender identity arises when the child is born with ambiguous genitalia.

Female↗
PubMed1995

A national breast cancer database.

The medical audit of technical and interpretive aspects of mammography has been recommended by a number of expert panels and as part of some regulations that govern the oversight of mammography. The value of the medical audit is to aid practitioners in the performance evaluation of mammography in their facilities. Collection and analysis of audit data at a regional or national level have the potential to allow for the comparison of practice-level performance with regional and national-level performance and to provide a public health tool for the evaluation and improvement of breast cancer detection. In addition, a regional and national-level breast cancer database has the potential for allowing monitoring and tracking of women participating in a screening program. Prior to establishing such a database, data must be protected from discovery and disclosure, and patient and physician confidentiality must be ensured.

Breast Neoplasms↗
PubMed1995

Fibrogenesis imperfecta ossium.

The clinical features, investigation, treatment and outcome of two adults with fibrogenesis imperfecta ossium are described. In this rare acquired disorder of bone, normal lamellar collagen is replaced by structurally unsound collagen-deficient tissue, which leads to extreme bone fragility and ununited fractures. Transmission microscopy and SEM showed striking ultrastructural changes in bone structure and mineralisation. Both patients had monoclonal IgG paraproteins in the plasma and one excreted monoclonal lambda light chains in the urine. No abnormal plasma cells were found in the bone marrow and there was no evidence of amyloid deposition in the tissues. In both patients initial treatment with 1 alpha-hydroxycholecalciferol appeared to be ineffective, but in one, repeated courses of melphalan and corticosteroids over three years together with 1 alpha-hydroxycholecalciferol produced striking clinical and histological improvement. The findings in these and other patients strongly suggest that paraproteinaemia is an integral feature of fibrogenesis imperfecta ossium, and this needs further investigation.

Adrenal Cortex Hormones↗
PubMed1995

Hold that x-ray: aspirate pH and auscultation prove enteral tube placement.

We report here a prospective study evaluating an alternative to the roentgenographic confirmation of "fine-bore" nasoenteral feeding tubes. Of 78 nasoenteral intubations in 46 patients using a Dobbhoff (Biosearch Medical Products) weighted enteral feeding tube, gastric aspirates were evaluated in 28. Auscultation was performed in all 78. Data was collected at initial placement prior to x-ray confirmation. Observers used color-coded pH paper to analyze gastric aspirate (pH < or = 4) and/or auscultation of the epigastrium to determine feeding tube position prior to x-rays. Auscultation alone was ineffective as a confirmatory test with only 6.3% specificity (p = 0.31). Aspiration to ascertain tube position was very accurate when pH < or = 4.0 (p = 0.0005) and when it was performed. A pH value of > 4 was not very helpful in predicting malposition (37%) especially when pH altering medications were used. Aspiration of contents was successful in 85% of patients. We conclude that when the pH of the nasogastric tube aspirate is < 4.0, x-ray films are not needed to prove the accuracy of tube placement. In other situations, a film is indicated since auscultation is inaccurate.

Adult↗
PubMed1995

Structural studies of myosin:nucleotide complexes: a revised model for the molecular basis of muscle contraction.

The structures of the MgADP-beryllium fluoride and MgADP-aluminum fluoride complexes of the truncated myosin head from Dictyostelium myosin II are reported. These reveal the location of the nucleotide complex and define the amino acid residues that form the active site. The tertiary structure of the beryllium fluoride complex is essentially identical to that seen previously in the three-dimensional structure of chicken skeletal muscle myosin. By contrast, significant domain movements are observed in the aluminum fluoride complex. These structural findings form the basis of a revised model for the structural basis of the contractile cycle. It is now suggested that the narrow cleft that splits the central 50-kDa segment of the heavy chain provides not only the communication route between the nucleotide-binding pocket and actin but also transmits the conformational change necessary for movement.

Adenosine Diphosphate↗
PubMed1995

Malignant gynecologic disease: applications of magnetic resonance imaging.

Malignancies of the female genital tract account for 25% of all cancers diagnosed in women. The decreasing incidence and mortality associated with cervical and uterine corpus carcinomas reflect earlier detection and improved therapies. Although not practical as a screening tool, magnetic resonance imaging is playing an expanding role in the diagnosis and staging of gynecologic cancers. Its unsurpassed soft tissue contrast resolution and multiplanar imaging capabilities allow better depiction of depth of tumor invasion and extent of local spread than either computed tomography or ultrasound.

Female↗
PubMed1995

Pregnancy-associated osteoporosis.

The clinical features, investigation and outcome in 24 patients with pregnancy-associated osteoporosis, followed for up to 24 years from the first pregnancy are described. Symptoms occurred most often in the first pregnancy (17 patients) at a mean age of 27 years (range 21-36); the most frequent was back pain in late pregnancy or post partum (n = 18); less common was hip (n = 5) or ankle (n = 1) pain. In most, symptoms improved soon after delivery. Four subjects had pre-existing disorders known to reduce bone density (corticosteroid therapy, heparin treatment, mild osteogenesis imperfecta and previous anorexia nervosa). Radiographs showed vertebral collapse or localized osteoporosis of the hip, with MRI evidence of oedema. Forearm bone mineral density (BMD) was sometimes normal, but spinal BMD (measured by DXA) was low. Bone biopsies in eleven patients showed features compatible with osteoblast failure. Except for the patient with mild osteogenesis imperfecta, cultured dermal fibroblasts synthesized and exported normal Type I collagen. In 14 subsequent pregnancies (10 patients) there was no recurrence in ten and mild symptoms in the remainder. Excluding one patient who had repeated osteoporotic fractures and vertebral collapse, the long-term prognosis was good.

Adult↗