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Biomedical subjects

S Williams

Publications and source records attributed to S Williams.

At least 451 records · Page 25Linked to original sources
PubMed1994

High-affinity alpha-thrombin binding to platelet glycoprotein Ib alpha: identification of two binding domains.

alpha-Thrombin binding to and activation of platelets are of major importance in the initiation of physiologic thrombi and in the genesis of arterial thrombus formation. We have studied the site(s) and affinity of thrombin binding to human platelets. Our studies of the peptide inhibition of thrombin binding indicate that the glycoprotein Ib alpha binding site is of high affinity, Kd approximately 10(-10) M, while the seven-transmembrane-domain site is a moderate-affinity thrombin binding site, Kd approximately 10(-8) M. Further studies to modulate the high- or moderate-affinity thrombin binding can be directed to a specific class of sites. This would allow partial or total inhibition of specific thrombin-platelet interaction(s) in different clinical settings.

Amino Acid Sequence↗
PubMed1994

Platelet adhesion to collagen in individuals lacking glycoprotein IV.

The Naka isoantigen is expressed on glycoprotein (GP) IV (CD36), a platelet membrane GP that has been identified as having a role in platelet interactions with collagen and thrombospondin and in binding Plasmodium falciparum-infected erythrocytes to endothelial cells and melanoma cells. We have studied normal platelets and Naka- platelets from two Japanese donors that have 1% of GPIV by concentration-dependent antibody binding and flow cytometry. We studied the adherence of normal and Naka- platelets to types I, III, and IV collagen in static and to type I collagen in flowing systems at high shear force. We have also studied aggregation of normal and Naka- platelets to type I collagen. Naka- platelets showed normal or increased aggregation to type I collagen and normal adhesion to types I, III, and IV collagen in the presence of Mg++ or EDTA. Platelet aggregation and adhesion were inhibited by the anti-alpha 2 beta 1 antibody 176D7 to the same extent in Naka- as in normal platelets. We also studied endogenous thrombospondin surface expression and found that thrombin-stimulated Naka- platelets expressed the same amount of thrombospondin as did normal platelets. From our studies with Naka- platelets, we cannot identify a definitive role for GPIV in platelet aggregation, in adhesion to types I, III, and IV collagen, or in endogenous thrombospondin binding to platelets.

Antigens, CD↗
PubMed1994

Discover diabetes: a community based screening programme for diabetic eye disease.

AIM: To evaluate a diabetic retinopathy screening programme for rural people with diabetes. METHOD: A retinal camera was transported to rural Waikato communities. Colour slide photographs were taken of the retina and lens of diabetic patients who had not had a previous review of their eyes by an ophthalmologist. The photographs were reviewed by an ophthalmologist, and those patients with an abnormality were referred back to their general practitioner who arranged further specialist assessment. RESULTS: Three hundred and ninety six patients have been screened and 116 patients have been referred on for specialist review. Fifty two of these patients had evidence of diabetic retinopathy, eight have been treated with laser treatment and one patient has had retinal surgery. No patients had to be recalled for repeat photographs. CONCLUSION: Retinal photography is an effective method of screening for sight threatening pathology in rural people with diabetes. Transportation of the retinal camera by station wagon is a practical way of making the service accessible.

Adult↗
PubMed1994

Traffic and noise in children's wards.

OBJECTIVE: To measure pedestrian traffic volumes and noise levels in paediatric open bay areas and discuss their impact on the care of sick children. METHODS: Between August and October 1992, we recorded the number and duration of entrances to two open bay areas comprising eight and ten beds respectively in a ward for infants and a ward for older children. Eight 24-hour periods (1200 to 1200) Friday to Saturday were assessed. Noise levels in decibels dB(A) were measured at 15-minute intervals. RESULTS: In an average 24-hour period, 5.5 (SD +/- 1.3) patients in the infants' ward and 9.5 (SD +/- 0.6) patients in the children's ward received 617 (SD +/- 85) and 683 (SD +/- 64) visits by 104 (SD +/- 20) and 110 (SD +/- 2) individuals respectively. The maximum numbers of visits per hour were 57 (SD +/- 14) and 54 (SD +/- 8) visits between 1500 and 1600 hours on Friday for each ward. Visits tended to be brief; 225 (SD +/- 23) and 217 (SD +/- 34) visits were of less than one minute's duration. The maximum noise levels of 57.3 dB(A) (SD +/- 6.3) and 64.6 dB(A) (SD +/- 3.5) occurred at 1000 Saturday and 1900 Friday and coincided with peak traffic volumes. CONCLUSIONS: Open bay areas generate high traffic volumes and coincident noise. Consideration should be given to either modifying or abolishing open bay areas and to general noise control measures.

Adolescent↗
PubMed1994

Platelet adhesion to collagen types I through VIII under conditions of stasis and flow is mediated by GPIa/IIa (alpha 2 beta 1-integrin).

Platelet adhesion to fibrillar collagens (types I, II, III, and V) and nonfibrillar collagens (types IV, VI, VII, and VIII) was investigated in the presence of physiologic concentrations of divalent cations under conditions of stasis and flow. Under static conditions, platelet adhesion was observed to collagen types I through VII but not to type VIII. Under flow conditions, platelet adhesion to collagen types I, II, III, and IV was almost independent of shear rates above 300/s. Collagen type V was nonadhesive. Platelet adhesion to collagen type VI was shear rate-dependent and optimal at a rate of 300/s. Collagen types VII and VIII showed minor reactivity and supported platelet adhesion only between shear rates 100 to 1,000/s. Monoclonal antibody (MoAb) 176D7, directed against platelet membrane glycoprotein Ia (GPIa; very late antigen [VLA]-alpha 2 subunit), completely inhibited platelet adhesion to all collagens tested, under conditions of both stasis and flow. Platelet adhesion to collagen type III at shear rate 1,600/s was only inhibited for 85%. The concentration of antibody required for complete inhibition of platelet adhesion was dependent on the shear rate and the reactivity of the collagen. An MoAb directed against GPIIa (VLA-beta subunit) partially inhibited platelet adhesion to collagen. These results show that GPIa-IIa is a major and universal platelet receptor for eight unique types of collagen.

Antibodies, Monoclonal↗
PubMed1994

Who comes to skin checks?

AIM: To examine the characteristics of persons attending skin checks carried out by the Cancer Society of New Zealand. METHODS: Persons aged 20 years or over attending three skin checks open to the public in the Taranaki region in the summer of 1991-2 were surveyed regarding the presence of risk factors for melanoma and reasons for attending the skin check. RESULTS: Overall, more women (n = 159) than men (n = 120) attended the clinics. Questionnaire results were available for 197 of those attending (110 women and 87 men). The average age of the sample was 49.4 years; 99% were from a European background. Forty percent of the sample had two or more of the following risk factors for melanoma: sun-sensitive skin, history of severe burning, red or fair hair, being treated for a skin cancer, and a family history of skin cancer. Fifty-one percent reported at least one change in a mole over the last 12 months, and 42% gave the presence of a worrying mark on their skin as a reason for coming. CONCLUSION: Those who attended the skin checks were likely to be at increased risk of skin cancer compared to the general population, and more often came because of a specific skin lesion than for a general skin check.

Adult↗
PubMed1994

Crystal and molecular structures of tricyclic neuroleptics.

The X-ray crystal structures of three tricyclic neuroleptics have been completed and are reported herein. These include amitriptyline hydrochloride (I), chlorprothixene hydrochloride (II), and ethopropazine hydrochloride (III). The structures were compared with the structures of similar molecules with similar pharmacological activity. It was found that there is a great deal of flexibility in the structures of these molecules, which makes it difficult to determine the pharmacologically active conformations. Crystallographic data: (I) C20H24NCl, monoclinic space group P2(1)/a, a = 13.812(4) A, b = 9.140(2) A, c = 14.345(4) A, beta = 96.82(2) degrees, Z = 4, final R = 0.059 for 1630 observed (l > 3 sigma(l)) reflections. (II) C18H20NSCl2.CHCl3, monoclinic space group C2/c, a = 29.416(4) A, b = 6.986(1) A, c = 23.374(3) A, beta = 109.78(1) degrees, Z = 8, final R = 0.046 for 1436 observed reflections. (III) C19H25N2SCl, monoclinic space group P2(1)/c, a = 8.849(1) A, b = 14.475(2) A, c = 14.832(1) A, beta = 98.72(1) degrees, Z = 4, final R = 0.039 for 2583 observed reflections.

Antidepressive Agents, Tricyclic↗
PubMed1994

Phenotypic analysis and characterization of CD34+ cells from normal human bone marrow, cord blood, peripheral blood, and mobilized peripheral blood from patients undergoing autologous stem cell transplantation.

Single- and multicolor flow cytometry were used to define progenitor subsets in normal human bone marrow and peripheral blood, cord blood, and blood following mobilization of CD34+ progenitor cells by cyclophosphamide or cyclophosphamide/etoposide/G-CSF treatment. CD34 cells were quantitated and subsets of CD34+ cells were defined by coexpression of CD33, CD13, CD10, CD19, CD45RA, and CD71. Myeloid and erythroid progenitors were quantitated by sorting single CD34+ cells into individual wells of 96-well plates containing methylcellulose, IL-3, GM-CSF, G-CSF, IL-6, and erythropoietin. Comparative studies of CD34 cells showed that the percentage of CD34+ mononuclear cells was greatest in blood samples from patients following mobilization treatment with cyclophosphamide/etoposide/G-CSF averaging 2%. By comparison, the remaining sample groups ranged from 1.68 to 0.15% CD34 cells in this order, bone marrow > cord blood > cyclophosphamide mobilized blood > peripheral blood. Comparison of CD34 cells per milliliter of bone marrow or blood showed a range of 22.4 x 10(4) to 0.65 x 10(4)/ml in the following order, bone marrow > chemotherapy/etoposide/G-CSF > cord blood > cyclophosphamide-mobilized blood. Comparative analysis of CD34 subsets from different sources showed significant differences, particularly bone marrow and blood samples. A distinct population of CD34+ CD19+ (Leu 12) CD10+ (CALLA) pre-B lymphocyte cells was defined in bone marrow with lower side and forward light scatter characteristics and was variable between donors (29.8 +/- 16.9%, mean +/- 1 SD; range, 3-54%; n = 8). This population was not found to a significant degree in blood and also expressed CD45RA (Leu 18). Coexpression studies of CD45RA and CD71 (transferrin receptor) expression on CD34+ cells defined a CD45RA- CD71+ population containing 89 +/- 6.3% (n = 4) BFU-E and a CD45RA+ CD71+ population that contained all CFU-GM (n = 4). LeuM7 (CD13) stained a larger percentage to a greater intensity than MY7 (CD13). Coexpression of CD45RA (Leu 18) and CD13 (LeuM7) defined a subset of CD13+ CD45RA+ cells enriched for CFU-GM and CFU-M with a cloning efficiency of 31%. Coexpression of CD33 (MY9) and CD13 (MY7) defined a population that was predominantly CFU-GM with a cloning efficiency of 38%. These studies define CD34+ phenotypes containing pure populations of B lymphocyte, granulocyte-macrophage, or erythroid progenitors and demonstrate the utility of multiparameter flow cytometry to define lineage-committed CD34+ cells.

Adult↗
PubMed1994

Salvage therapy for recurrent and refractory ovarian cancer with high-dose chemotherapy and autologous bone marrow support: a Gynecologic Oncology Group pilot study.

Nine patients with recurrent or refractory epithelial ovarian carcinoma following previous chemotherapy were treated with high-dose carboplatin (300 mg/m2) and ifosfamide according to a dose escalation schedule (1.50, 1.75, 2.00 g/m2), each given intravenously daily for 5 days with autologous bone marrow support. Eight of the nine patients were evaluable for response. Five achieved complete response (CR), all of whom relapsed at 4, 5, 6, 8, and 23 months following treatment. Two partial responses persisted for 6 months, and one patient with stable disease progressed after 2 months and has since died of disease. The median duration of remission was 6 months. The treatment was well tolerated across the doses of ifosfamide with the exception of one treatment-related death which was due to acute renal failure and central nervous system toxicity from ifosfamide. It appears that the use of high-dose chemotherapy with autologous bone marrow support in the treatment of ovarian cancer produced a high rate of response of short duration in this small group of heavily pretreated women.

Adult↗
PubMed1994

Depression and the development of cancer: a meta-analysis.

There is considerable support among members of the public and health professionals for the view that depression is an aetiological factor in the development of cancer. We review evidence for this hypothesis based upon prospective longitudinal studies measuring depression at time 1 and subsequent incidence of cancer over the intervening period to time 2. A meta-analysis of available studies indicates a small, but marginally statistically significant association between depression and the later development of cancer. However, the practical significance of this association for the prevention of cancer is negligible.

Depression↗
PubMed1994

Multidimensional health locus of control beliefs and psychological health for a sample of mothers.

Five multidimensional health locus of control (MHLC) types for 772 women whose children are enrolled in a longitudinal study of their health and development were identified. The MHLC is composed of an internal and two external dimensions (chance and powerful others). The five independent MHLC clusters were: pure internal; believer in control; pure chance; yea-sayer; and nay-sayer. Women with high scores on the three dimensions of the MHLC (yea-sayer) compared with the rest of the sample were significantly more likely to be from a lower socio-economic status, score lower on a general verbal intelligence test and higher on the Neuroticism and Lie Scales of the Eysenck Personality Inventory. They rated their overall health as significantly poorer, and reported more symptoms of depression compared with the other groups. A pure internal locus of control was strongly associated with the report of good health. Women with a strong belief in internal and powerful other loci of control were significantly more likely to have received treatment for their depression compared with other groups. Help-seeking for children's problem behaviour did not vary significantly with MHLC groups. The present study replicated five out of six MHLC types identified in an earlier study, and established the external validity of the MHLC types on measures of health status. The findings support the use of MHLC types in future research on health locus of control.

Adolescent↗
PubMed1994

Body size and the menarche: the Dunedin Study.

PURPOSE: We wished to elucidate the relationships among body size variables and age of menarche for New Zealand girls. METHODS: Body size variables were measured repeatedly over eighteen years and age of menarche recorded for 415 girls enrolled in the Dunedin Multidisciplinary Health and Development Study. RESULTS: Girls who were taller and heavier with a higher body mass index than their peers from 7 years of age reached menarche early: height was the most important determinant. Early maturing girls were overtaken in height by the later-maturing girls by fifteen but remained heavier even at eighteen. The daughters of tall mothers matured later. The mean weight at menarche was 41.4 kg, height 149.4 cm, body mass index 18.4, and age 12.9 years. CONCLUSIONS: The daughters of short women matured early and continued growing heavier, but they stopped growing taller and were overtaken in height by the later-maturing daughters of tall women.

Adolescent↗
PubMed1994

Major determinants of consumer satisfaction with primary care in different health systems.

It is becoming increasingly recognized that patient or 'consumer' views should be taken into account as part of a comprehensive assessment of quality of care. This paper reports a study carried out in four European countries about consumer satisfaction with primary care. The results showed that higher levels of general satisfaction with general practitioner services were found in Canterbury (95%) and Ioannina (87%) than Belgrade (85%) and Moscow (62%). Further analysis of the data showed that in all four cities the key dimensions of satisfaction with general practitioner care are both the nature in quality of the doctor-patient relationship and the GP's professional skills. The implications of these findings are discussed.

Adolescent↗
PubMed1994

Clinical utility of bone SPECT scintigraphy in renal metastases from primary osteosarcoma.

Renal metastases from primary osteosarcomas are rather uncommon and rarely diagnosed early because the patients are asymptomatic and frequently die from other metastatic involvement before renal symptoms develop. The authors present a patient with two clinically silent renal metastases from primary osteosarcoma of the right femur 2 years after surgery of the primary lesion that was first detected on radionuclide bone imaging. Subsequently, a CT scan and a CT guided needle biopsy were performed for confirmation. The patient underwent a left nephrectomy and two separate lesions were proven to be metastatic osteosarcoma. The clinical importance of the nuclear bone scan in the initial management, as well as in the subsequent follow-up of patients after surgery, cannot be overemphasized.

Adolescent↗
PubMed1994

Evaluating the long-term performance of a foam-core hospital replacement mattress.

Many hospitals have begun replacing their standard mattresses with pressure-reducing foam mattresses to eliminate the costly overlays that have been used for comfort and to protect patients at risk for development of pressure ulcers. Although researchers have tested the performance of new mattresses and have shown that many may be of use with patients at high risk, no information is available on the pressure-reducing capabilities of used mattresses. This study was designed to evaluate changes with use in the support characteristics of foam-core hospital replacement mattresses. In the first part of the study, interface pressure measurements were made at regular intervals over an extended period of use. Sixty mattresses were randomly selected from 750 mattresses currently in use at St. Luke's Episcopal Hospital, Texas Medical Center, Houston. The mattresses were labeled and marked at three selected points, and interface pressures under a standard load were measured at approximately 3-month intervals for 12 months. In the second part of the study, the stiffness of the foam, a measure of the foam's ability to support a weight, was measured at selected points on the mattresses. Patient reports of discomfort in the sacral area and of "sinking" into the middle of the mattress prompted this phase of the study. The stiffness profiles of 25 new mattresses were compared with those of 25 randomly selected mattresses that had been in regular use for at least 24 months. Data analyzed from part one showed trends that indicated that the interface pressures increased at each site during the course of the study; however, an analysis of variance indicated that the changes were not statistically significant during the time frame of the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Beds↗
PubMed1994

Health beliefs among New Zealand adolescents.

A modified version of the Multidimensional Health Locus of Control (MHLC) scale was administered to 837 adolescents, aged 15 years, to assess their beliefs about health. There were significant sex differences on the total scores of the internal and powerful others dimensions of the scale. MHLC beliefs were not significantly associated with self-reported ratings of general health or mental health. Significantly more distress due to the experience of negative life events was reported by females with a strong internal locus of control. Maternal health beliefs showed stronger associations with daughters' health beliefs than sons'. For males, strong beliefs in an internal locus of control and weak beliefs in chance were significantly associated with aspects of attachment, social support and self-perceived strengths. There were weak correlations for the majority of associations between health beliefs and health measures and most of the adolescents reported either good or very good health. The findings suggest that adolescents' health beliefs may be quite different from those of adults.

Adolescent↗
PubMed1994

Reading attainment and juvenile delinquency.

Structural equation modelling was used with data from a longitudinal study of child development (N = 698) to examine relationships between early reading attainment and antisocial behaviour at ages 7 and 9 years and subsequent reading and delinquent behaviour in adolescence. While reading, analysed as a continuous variable, did not directly influence later delinquency, antisocial behaviour during the early school years was strongly predictive of delinquency at age 15 years, particularly for boys, and had a detrimental effect on reading. These findings were independent of social disadvantage, and were unchanged by adjusting reading scores for IQ. Reading disability at 9 years old, however, predicted conduct disorder at age 15 in boys.

Achievement↗