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Biomedical subjects

C Lawrence

Publications and source records attributed to C Lawrence.

At least 37 records · Page 2Linked to original sources
PubMed1989

Advanced-stage endometrial cancer: contributions of estrogen use, smoking, and other risk factors.

The contributions of estrogen replacement therapy, smoking, and other risk factors to the development of advanced-stage (2-4) endometrial cancer were evaluated in a case-control study of women 40-69 years old from upstate New York. Eighty-four cases and 168 matched community controls were interviewed in person about estrogen exposure and other risk factors. Despite a statistically significant increase in risk with longer use of estrogen pills (P less than 0.05), estrogen exposure actually contributed little to the overall risk of advanced-stage endometrial cancer. Other physical conditions (increased weight, lower parity, diabetes) and socioeconomic factors (education, access to medical services) largely accounted for advanced-stage disease. The evidence in this study does not support the hypothesis that women who smoke have a lower risk than nonsmokers of developing advanced-stage endometrial cancer.

Adult↗
PubMed1989

Modelling of reference values for size at birth.

Data from the Swedish Medical Birth Registration, 1977-1981 were used to apply methods of constructing reference standards for size at birth. Using clinical information a 'healthy' sub-population was extracted. The conditional distributions of birthweight (BW) and birthlength (BL) for each week of Gestational age, and the conditional distribution of birthweight given birthlength were modelled using truncated Normal distributions, after making use of Box-Cox power transformations. Spline functions were then used in conjunction with a multiplicative method to obtain appropriate percentage point curves. Examples of this analysis are given.

Birth Weight↗
PubMed1989

Teenage sexuality: implications for controlling AIDS.

A study on 761 teenagers aged 15-17 years showed that 56% of both sexes had had a steady or serious relationship. For about 40% of both sexes intercourse was a part of this relationship. Teenagers know how AIDS is transmitted, but only one third indicated personal concern about the epidemic. Only a fifth anticipate a single monogamous relationship. Significantly more girls than boys are planning to have fewer partners. Of these not anticipating monogamy three quarters mentioned the use of condoms. If education is to be effective in reducing the AIDS epidemic it must be sufficiently relevant to create and maintain changes in life style and must also educate teenagers before they have established patterns of behaviour.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Bleeding time. A guide to its diagnostic and clinical utility.

Although the bleeding time is the most widely used clinical test employed to assess platelet function, its indications are poorly defined. The test is commonly used as a preoperative screen to predict hemorrhage, but the data supporting this indication are contradictory at best. In this review we highlight the physiologic basis for the bleeding time and survey the literature for data supporting the valid indications for its use. The bleeding time is a useful test for assessing platelet function in patients with hemorrhagic disorders. Its utility in providing helpful clinical information in patients who do not have a known bleeding diathesis by history is minimal. Specific recommendations regarding the rational use of the bleeding time for the preoperative evaluation of patients are presented.

Bleeding Time↗
PubMed1989

Who is holding the baby?

A survey of neonatal units has been undertaken to establish how many maternity units have to separate mothers from their well, low birthweight babies or low dependency special care babies. The study also looked at some differences in the hospitals practising transitional care, or shared care with mother, and a group of maternity wards looking after babies down to 1.8 kg on normal maternity wards.

Family↗
PubMed1988

Diagnostic clues in an adult case of Leigh's disease.

A previously-well 32-year-old woman presented with episodes of severe headache, neck pain, numbness of the tongue and facial sweating. In the course of her illness she became abulic, blind and quadriparetic and she suffered recurrent episodes of coma during which she became decerebrate and her brain-stem reflexes were absent. She had an adult form of Leigh's disease, which is an extremely-rare degenerative condition of unknown cause. The clinical, neuroradiological and neuropathological features are presented.

Adult↗
PubMed1988

Functional topography of band 3: specific structural alteration linked to functional aberrations in human erythrocytes.

Band 3 is the major anion transport polypeptide of erythrocytes. It appears to be the binding site of several glycolytic enzymes. Structurally, band 3 is the major protein spanning the erythrocyte membrane and connects the plasma membrane to band 2.1, which binds to the cytoskeleton. In the present study, we report an alteration of band 3 molecule that is associated with the following changes: erythrocyte shape change from discoid to "thorny cells" (acanthocytes), restriction of rotational diffusion of band 3 in the membrane, increase in anion transport, and decrease in the number of high-affinity ankyrin-binding sites. Changes in erythrocyte IgG binding, glyceraldehyde-3-phosphate dehydrogenase, fluorescence polarization (indicative of membrane fluidity), and other membrane proteins as determined by polyacrylamide gel electrophoresis were not detected. Cells containing the altered band 3 polypeptide were obtained from individuals with abnormal erythrocyte morphology. Two-dimensional peptide maps revealed differences in the Mr 17,000 anion transport segment of band 3 consistent with additions of tyrosines or tyrosine-containing peptides. The data suggest that (i) this alteration of band 3 does not result in accelerated aging as does cleavage and (ii) structural changes in the anion transport region result in alterations in anion transport.

Acanthocytes↗
PubMed1988

Teenage relationships and sex education.

Most of the consequences of early intercourse affect the woman and much research has focused upon her. As part of a study on teenage pregnancy, where 137 women were interviewed, 46 men were also interviewed. They were less likely to have had teaching about sex from parents and were subject to less parental supervision than the women. Both sexes had had similar experience of school sex education. Just under half of the men started having intercourse before 16 years. Over half of both sexes were initiated by an experienced partner and for 15/25 (60%) of the men this was within the first month of a relationship. Most men had had several partners and 27/99 (27%) of teenage women at least three, most in the context of stable relationships. 'Serial monogamy' exposes each partner indirectly to their partners previous partners (with the associated medical risks). Education must help teenagers make decisions about sexual involvement that take account of these facts and the implications for their own future health and happiness.

Adolescent↗
PubMed1987

Distribution of accessible surfaces of amino acids in globular proteins.

Globular proteins fold into compact particles with interior amino acid residues shielded from the surrounding aqueous environment. An early hypothesis holds that entropic hydrophobic forces drive this phenomenon. However, previous analyses based on a binary description of the accessible surfaces of amino acid residues in proteins did not support this hypothesis. This report shows that a complete description of accessible surface areas is given by parametric distribution functions with three modes. The modes are formed by partitioning the available accessible surface area of the amino acids into three segments; the data for each segment are characterized by a mode-specific model. In the "repulsive" mode, probabilities of accessibility decrease exponentially with exposed surface area, as predicted by the hydrophobic hypothesis. A distinct "buried" mode is needed to account for an excess of residues at or near zero accessibility for most amino acids, consistent with the use of binary descriptions of accessibility. A third mode exists which is termed "near neutral" because it is described by a nearly uniform distribution of accessibility for the hydrophilic amino acids. Empirical energies calculated for the repulsive mode correlate well with measured free energies of transfer of amino acids from water to organic solvents, while those from the buried mode correlate well with measured free energies of hydration of the side chains. Poor cross correlations between these energies give an explanation for the previous conflict in interpreting these data.

Amino Acids↗
PubMed1987

Radiographic abnormalities in coagulation factor VII deficiency.

We report the plain film findings as knees and elbows in two patients with congenital coagulation factor VII deficiency. The radiographic features resemble hemophilia, although the joint manifestations are milder, appear later in life, and occur in both men and women.

Adolescent↗
PubMed1987

[Calculation of intracardiac shunt using Doppler echocardiography].

The purpose of this study was to assess the accuracy of a quantitative two-dimensional Doppler echocardiographic method for estimation of intracardiac shunts. The ratio of pulmonary to systemic flow (Qp/Qs) was evaluated by duplex Doppler echocardiography in 20 patients with various intracardiac shunts. Right and left ventricular stroke volumes (RSV, LSV) were determined from the recordings of ejection blood flow velocity and diameter at the level of the pulmonary and aortic orifices in each ventricular outflow tract. The ratio RSV/LSV, determined by duplex Doppler echocardiography, was compared with Qp/Qs by oxymetry. The Doppler echocardiograms were of sufficient quality for shunt calculation in 15/20 patients (75%). The RSV/LSV for ten normal subjects was 0.99 +/- 0.05 (mean +/- SD), whereas the RSV/LSV for 15 patients with intracardiac shunts, 2.6 +/- 0.5, was significantly higher than that for normal subjects (p less than 0.01). In 12/15 patients, the Doppler study estimated the severity of intracardiac shunting correctly. The presence of complex anatomic situations, a wide pulmonary artery or significant semilunar regurgitation seem to have a negative impact on the Doppler echocardiographic shunt calculation. Our findings indicate that, with a few limitations, the Doppler index RSV/LSV is clinically useful in the estimation of the magnitude of the shunt flow in patients with intracardiac shunts.

Adolescent↗