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Biomedical subjects

S Williams

Publications and source records attributed to S Williams.

At least 91 records · Page 5Linked to original sources
PubMed2001

Nicotine dependence and attempts to quit or cut down among young adult smokers.

AIMS: To describe tobacco smoking behaviours, attempts to cut down or quit, and estimate the prevalence of DSM-IV nicotine dependence among young adult smokers. To relate these findings to population demand for national Quitline services. METHODS: Confidential interviews were conducted during the assessment of the Dunedin Multidisciplinary Health and Development Study birth cohort at age 26 years. Current smokers who had smoked daily for at least one month during the twelve months before interview were asked questions to identify nicotine dependence, based on DSM-IV criteria. RESULTS: Overall, 40% (n = 386) of the cohort followed up were current smokers who met the twelve month daily smoking criterion, one third of whom fulfilled DSM-IV criteria for nicotine dependence. The mean number of attempts to quit or cut down in the past year was 1.2. Assuming that each attempt represents a potential call to the Quitline, more than 5500 calls per month might be anticipated from the 25-29 year age group and in excess of 40 000 from the total New Zealand population, eighteen years and older. CONCLUSIONS: Results indicate that many young adult smokers are potential users of smoking cessation services and many are nicotine dependent. In order to satisfy this reservoir of need and reduce the population burden of ill-health and premature death due to tobacco smoking, resources should continue to be provided to support and enhance tobacco control programmes with proven effectiveness in helping smokers to quit.

Adult↗
PubMed2001

Generation and refinement of peptide mimetic ligands for paratope-specific purification of monoclonal antibodies.

Paratope-specific purification of antibodies has distinct advantages over conventional methods of antibody purification with respect to its capacity to isolate product of high purity and immunoreactivity. The present report addresses the problems of identifying peptide ligands for the purification of antibodies reactive with nonprotein antigens. Using an anti-steroid antibody as the model, a lead sequence that bound antibody was identified from a peptide phage display library. The minimum binding unit in this sequence was deduced using a series of truncated peptides synthesized on the heads of polyethylene pins. Replacement Net analysis of the minimum binding unit identified peptides with increased affinity for the antibody. The affinity-matured peptide mimotope bound antibody in solution. By molecular modeling the peptide was superimposable onto estrone-3-glucuronide localized in the crystal structure of the antibody binding pocket. In order to resolve problems of presentation posed by the reversal of orientation of the peptide on the affinity matrix compared with the pins, the mimotope peptide was synthesized in reverse sequence using d-amino acids. The resulting affinity matrix was effective for the purification of antibody. Eluted product demonstrated molecular homogeneity and high immunoreactivity. It is concluded that the combination of biological and chemical library techniques described provides a method for the generation and affinity maturation of mimotopes for antibodies against nonprotein antigens.

Animals↗
PubMed2001

The dendritic cell populations of mouse lymph nodes.

The dendritic cells (DC) of mouse lymph nodes (LN) were isolated, analyzed for surface markers, and compared with those of spleen. Low to moderate staining of LN DC for CD4 and low staining for CD8 was shown to be attributable to pickup of these markers from T cells. Excluding this artifact, five LN DC subsets could be delineated. They included the three populations found in spleen (CD4(+)8(-)DEC-205(-), CD4(-)8(-)DEC-205(-), CD4(-)8(+)DEC-205(+)), although the CD4-expressing DC were of low incidence. LN DC included two additional populations, characterized by relatively low expression of CD8 but moderate or high expression of DEC-205. Both appeared among the DC migrating out of skin into LN, but only one was restricted to skin-draining LN and was identified as the mature form of epidermal Langerhans cells (LC). The putative LC-derived DC displayed the following properties: large size; high levels of class II MHC, which persisted to some extent even in CIITA null mice; expression of very high levels of DEC-205 and of CD40; expression of many myeloid surface markers; and no expression of CD4 and only low to moderate expression of CD8. The putative LC-derived DC among skin emigrants and in LN also showed strong intracellular staining of langerin.

Animals↗
PubMed2001

Jugular venous emboli of brain tissue induced in sheep by the use of captive bolt guns.

Emboli of central nervous tissue were detected in the jugular venous blood of two of 15 sheep stunned with a conventional cartridge-operated captive bolt gun and in two of 15 sheep stunned with a pneumatically activated gun. No emboli were detected in arterial blood from these sheep or in venous blood from sheep stunned electrically. Emboli from an animal with BSE could transmit the disease to people.

Abattoirs↗
PubMed2001

Structural magnetic imaging of the hippocampus in early onset schizophrenia.

BACKGROUND: Previous literature suggests that hippocampal volume reductions in schizophrenia may occur either during adolescence or at the point of transition to overt psychosis. The authors tested these hypotheses by examining the hippocampal formation in adolescents with recent onset schizophrenia. METHODS: We compared the volumes of the left and right hippocampus, obtained using stereologic methods from magnetic resonance brain images, from 40 adolescents with recent onset schizophrenia to those of an equal number of matched healthy control subjects. Symptoms were rated using the Positive and Negative Syndrome Scale. RESULTS: Compared with control subjects, adolescents with schizophrenia had reduced whole brain volume. After adjusting for brain volume, no group differences were observed in hippocampal volume. Duration of illness was negatively correlated with the volume of the left hippocampus. We found no effect of pregnancy and birth complications or family history of psychosis on hippocampal volumes. There was a negative correlation between severity of psychopathology and hippocampal volumes, which was significant for negative symptoms. CONCLUSIONS: Specific hippocampal volume reductions in early onset schizophrenia do not seem to predate the onset of or to occur at the point of transition to psychosis but may develop in adolescence during the early stages of the illness.

Adolescent↗
PubMed2001

A review of mechanisms controlling ovulation with implications for the anovulatory effects of polychlorinated dibenzo-p-dioxins in rodents.

Polychlorinated dibenzo-p-dioxins (PCDDs) can impinge on female fertility by preventing ovulation. In this review, the aspects of normal ovulatory physiology most relevant to our current understanding of PCDD action on the ovary are briefly reviewed. This is followed by a comprehensive assessment of data relevant to the effects of PCDDs during ovulation in the rat. PCDDs interrupt ovulation through direct effects on the ovary in combination with dysfunction of the hypothalamo-hypophyseal axis.

Animals↗
PubMed2001

A germline deletion of p14(ARF) but not CDKN2A in a melanoma-neural system tumour syndrome family.

The melanoma-astrocytoma syndrome is characterized by a dual predisposition to melanoma and neural system tumours, commonly astrocytoma. Germline deletions of the region on 9p21 containing the CDKN2A and CDKN2B genes and CDKN2A exon 1beta have been reported in kindreds, implicating contiguous tumour suppressor gene deletion as a cause of this syndrome. We describe a family characterized by multiple melanoma and neural cell tumours segregating with a germline deletion of the p14(ARF)-specific exon 1beta of the CDKN2A gene. This deletion does not affect the coding or minimal promoter sequences of either the CDKN2A or CDKN2B genes. Our results are consistent with either: (i) loss of p14(ARF) function being the critical abnormality associated with this syndrome, rather than contiguous loss of both the CDKN2A and CDKN2B genes as suggested previously; or (ii) disruption of expression of p16 by mechanisms as yet unknown.

Astrocytoma↗
PubMed2001

N-acetyl alpha-D-glucosaminidase from the venom of African puff adder (Bitis arietans).

The activity of N-acetyl-alpha-D-glucosaminidase from venom of the African puff adder (Bitis arietans) has been detected. The enzyme from the venom was purified by chromatography on Q-sepharose, CM-cellulose, and N-acetyl-alpha-D-glucosamine-agarose affinity column. The enzyme has a molecular weight of 102 kDa determined by size exclusion chromatography on Sephacryl 200. It migrated as a 51-kDa band on SDS polyacrylamide gels. The enzyme is maximally active at pH 5.5 and 40 degrees C. The B. arietans NAGase hydrolyzed exclusively terminally linked alpha-(1-4) GlcNAc residues from nonreducing ends of oligosaccharides. It hydrolysed chito-oligosaccharide, MU-GlcNAc and chitobiose with K(M) values of 0.15 mM and 1.22 mM, respectively. Swollen chitin and oligosaccharide above (GlcNAc)(4) were not hydrolysed by the enzyme. B. arietans NAGase was strongly inhibited noncompetitively by Hg(2+), competitively by 1-thio-beta-D-GlcNAc and N-acetyl glucosamine (NAG) with K(i) of 0.55, 0.25 and 8 mM, respectively. Colombin the active component of antivenom preparation from Aristolodia albida inhibited the enzyme competitively with K(i) of 0.6 mM. Delineation of the active site by chemical modification revealed the involvement of His and Trp in the catalysis of the enzyme.

Acetylglucosaminidase↗
PubMed2001

Reasons for failure of glyceryl trinitrate treatment of chronic fissure-in-ano: a multivariate analysis.

PURPOSE: Although glyceryl trinitrate ointment has become the first-line treatment for chronic anal fissure, healing rates are lower than after lateral internal sphincterotomy. The purpose of this study was to identify which factors are associated with treatment failure of glyceryl trinitrate ointment. METHODS: All patients who presented with chronic anal fissure from March 1997 to November 1998 were treated with 0.2 percent glyceryl trinitrate ointment. They were prospectively evaluated until healing or lateral internal sphincterotomy occurred, and long-term follow-up was obtained by standardized telephone questionnaire. A Cox model multivariate analysis was used with seven variables to determine significant factors related to healing. RESULTS: Sixty-four patients (42 men and 22 women; mean age, 37.5 years) with chronic fissure-in-ano were treated with 0.2 percent glyceryl trinitrate ointment. Sentinel piles were observed in 19 patients (29.7 percent). Twenty-six patients (40.6 percent) were healed initially, but 12 (46.2 percent) experienced recurrence. Mean follow-up time was 15.6 (+/-5.5) months. Twenty-nine patients (45.3 percent) had known risk factors for anal fissure, including constipation (n = 21; 32.8 percent), recent childbirth (n = 6; 9.3 percent), colonoscopy (n = 1; 1.6 percent), and anoreceptive intercourse (n = 1; 1.6 percent). Fissures were significantly less likely to heal initially (P < 0.05), more likely to recur (P < 0.05), and more likely to remain unhealed in the long term (P < 0.05) in the presence of a sentinel pile. Fissures with a history of more than six months were less likely to heal initially (P < 0.05). CONCLUSION: The presence of a sentinel pile adversely affects the outcome of treatment of chronic anal fissures with glyceryl trinitrate ointment, and a long history of the fissure reduces the rate of initial healing. Reasons for these findings are discussed.

Administration, Topical↗
PubMed2001

In situ DNA fragmentation occurs in white matter up to 12 months after head injury in man.

Using the terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphate nick-end labelling (TUNEL) histochemical technique, evidence for DNA fragmentation was sought in the hippocampus, cingulate gyrus and insula from 18 patients who survived for up to 12 months after head injury, and 15 matched controls. Both conventional (haematoxylin and eosin and Luxol-fast blue/cresyl violet) and immunohistochemical (glial fibrillary acidic protein, CD68) staining techniques were used to identify the cellular response and its time course in the regions of interest. Only the occasional TUNEL-positive (+) cell/unit area was seen in any area of the control brains. In contrast there were more TUNEL+ cells/unit area in the injured brains. TUNEL+ cells were present in white matter and their average numbers ranged from three to five per unit area for up to 3 months survival in the extreme capsule and the parasagittal white matter, with similar numbers in the hippocampus, and between two and three per unit area in the parasagittal white matter and hippocampus of the cases surviving up to 12 months post injury. Between one and two TUNEL+ cells/unit area were also seen in grey matter, of which most appeared as neurones. About 5% of the TUNEL+ cells in white matter had the morphological features of apoptosis: the corresponding figure in grey matter was less than 1%. In many instances the TUNEL+ cells were also CD68+ and appeared by light microscopy to be macrophages. It was concluded that, as reflected by TUNEL histochemistry, long-term DNA fragmentation is present in white matter after traumatic brain injury in man.

Adolescent↗
PubMed2001

Mechanical properties of a novel PVA hydrogel in shear and unconfined compression.

Poly(vinyl alcohol) (PVA) hydrogels have been proposed as promising biomaterials to replace diseased or damaged articular cartilage. A critical barrier to their use as load-bearing tissue replacements is a lack of sufficient mechanical properties. The purpose of this study was to characterize the functional compressive and shear mechanical properties of a novel PVA hydrogel. Two formulations of the biomaterial were tested, one with a lower water content (75% water), and the other with higher water content (80% water). The compressive tangent modulus varied with biomaterial formulation and was found to be statistically strain magnitude and rate dependent. Over a strain range of 10-60%, the compressive modulus increased from approximately 1-18 MPa, which is within the range of the modulus of articular cartilage. The shear tangent modulus (0.1-0.4 MPa) was also found to be strain magnitude dependent and within the range of normal human articular cartilage, but it was not statistically dependent on strain rate, This behavior was attributed to the dominance of fluid flow and related frictional drag on the viscoelastic behavior. Compressive failure of the hydrogels was found to occur between 45 and 60% strain, depending on water content.

Biocompatible Materials↗
PubMed2001

International Child Care Practices Study: infant sleeping environment.

BACKGROUND: The International Child Care Practices Study (ICCPS) has collected descriptive data from 21 centres in 17 countries. In this report, data are presented on the infant sleeping environment with the main focus being sudden infant death syndrome (SIDS) risk factors (bedsharing and infant using a pillow) and protective factors (infant sharing a room with adult) that are not yet well established in the literature. METHODS: Using a standardised protocol, parents of infants were surveyed at birth by interview and at 3 months of age mainly by postal questionnaire. Centres were grouped according to geographic location. Also indicated was the level of SIDS awareness in the community, i.e. whether any campaigns or messages to "reduce the risks of SIDS" were available at the time of the survey. RESULTS: Birth interview data were available for 5488 individual families and 4656 (85%) returned questionnaires at 3 months. Rates of bedsharing varied considerably (2-88%) and it appeared to be more common in the samples with a lower awareness of SIDS, but not necessarily a high SIDS rate. Countries with higher rates of bedsharing appeared to have a greater proportion of infants bedsharing for a longer duration (>5 h). Rates of room sharing varied (58-100%) with some of the lowest rates noted in centres with a higher awareness of SIDS. Rates of pillow use ranged from 4% to 95%. CONCLUSIONS: It is likely that methods of bedsharing differ cross-culturally, and although further details were sought on different bedsharing practices, it was not possible to build up a composite picture of "typical" bedsharing practices in these different communities. These data highlight interesting patterns in child care in these diverse populations. Although these results should not be used to imply that any particular child care practice either increases or decreases the risk of SIDS, these findings should help to inject caution into the process of developing SIDS prevention campaigns for non-Western cultures.

Beds↗
PubMed2001

Case-mix adjusted incidence of pressure ulcers in acute medical and surgical wards.

Pressure ulcers cause considerable pain and suffering and are also a very expensive drain on NHS funding. Measuring prevalence is particularly useful for guiding use of resources whereas incidence is an outcome indicator of quality of care. Patients and illnesses vary and it may be misleading to make assumptions based on crude incidence figures. A system of case-mix adjustment has been developed in Glasgow (GPSISS). This study used GPSISS to measure case-mix adjusted incidence of pressure ulcers in over 15,000 acute hospital patients. The incidence of pressure ulcers ranged from 1.1% to 2.7%. These low rates, and the time cost and effort involved in ensuring quality data, suggests that significant differences in quality of care may be demonstrated more quickly using processes rather than outcomes and may more directly identify where changes in practice are required.

Adult↗
PubMed2001

ACCCN national nursing workforce survey of intensive care units.

A descriptive study was designed and implemented by the Australian College of Critical Care Nurses (ACCCN) Workforce Planning Advisory Committee to capture data pertaining to workforce issues of intensive care nurses. All intensive care units (ICUs) within Australia were mailed a self reporting survey. Despite a low response rate (52 per cent) and difficulty reported by respondents in gaining the appropriate data requested, the results revealed an interesting snapshot of the intensive care nursing workforce. Types of services offered by units varied considerably; paid overtime hours were low (< 2 per cent of total hours worked) and use of both part-time and agency staff was also low (10 per cent of total hours worked). Private hospitals utilised a greater proportion of part-time and agency nursing staff than public hospitals (20:10 per cent). The turnover rate for registered nursing staff was estimated at 18 per cent, with education, skill acquisition and improved communication reported as the major incentives used by managers to attract and retain staff. This study demonstrated that valuable data are currently uncaptured and recommends a more refined process of a national database to record and manage this important information for future workforce planning.

Australia↗
PubMed2001

Low self-esteem and hopelessness in childhood and suicidal ideation in early adulthood.

This study examined the longitudinal relationship between family characteristics in early childhood. self-esteem, hopelessness and thoughts of self-harm in the midchildhood years, and suicidal ideation at ages 18 and 21. Path analysis was used to establish separate models for boys and girls. The results suggested different pathways to later suicidal ideation for boys and girls. For boys, suicidal ideation seemed to have stronger roots in childhood, with significant paths from low self-esteem and hopelessness to early thoughts of self-harm and thence to later ideation. For girls, self-esteem had a small but significant direct effect on later suicidal ideation. The findings provide support for the idea that individual characteristics such as feelings of hopelessness and low self-esteem act as "generative mechanisms," linking early childhood family characteristics to suicidal ideation in early adulthood.

Adolescent↗