PubMed Health⌕ Search

Biomedical subjects

S A Williams

Publications and source records attributed to S A Williams.

At least 55 records · Page 3Linked to original sources
PubMed1999

Chemiluminescent detection of sequential DNA hybridizations to high-density, filter-arrayed cDNA libraries: a subtraction method for novel gene discovery.

A chemiluminescent approach for sequential DNA hybridizations to high-density filter arrays of cDNAs, using a biotin-based random priming method followed by a streptavidin/alkaline phosphatase/CDP-Star detection protocol, is presented. The method has been applied to the Brugia malayi genome project, wherein cDNA libraries, cosmid and bacterial artificial chromosome (BAC) libraries have been gridded at high density onto nylon filters for subsequent analysis by hybridization. Individual probes and pools of rRNA probes, ribosomal protein probes and expressed sequence tag probes show correct specificity and high signal-to-noise ratios even after ten rounds of hybridization, detection, stripping of the probes from the membranes and rehybridization with additional probe sets. This approach provides a subtraction method that leads to a reduction in redundant DNA sequencing, thus increasing the rate of novel gene discovery. The method is also applicable for detecting target sequences, which are present in one or only a few copies per cell; it has proven useful for physical mapping of BAC and cosmid high-density filter arrays, wherein multiple probes have been hybridized at one time (multiplexed) and subsequently "deplexed" into individual components for specific probe localizations.

Animals↗
PubMed1999

Cultural barriers to successful communication during orthodontic care.

OBJECTIVE: To determine to what extent barriers related to culture and language, and how inappropriate expectations might impede orthodontic care, among Pakistani Muslims when compared to white Caucasians from similar socio-economic backgrounds in Bradford, UK. DESIGN: Semi-structured interviews. SETTING: Dentists were interviewed in the clinic. Parents and children were interviewed separately in the waiting room or in adjacent rooms depending on availability. PARTICIPANTS: Four dentists working in the Community and Hospital Dental Services, 30 children and 10 parents of white and Pakistani origin. RESULTS: Among the white Caucasian groups, three-way communication involving parents, children and dentist enhanced understanding, supported orthodontic treatment and reinforced the need for good home care. Among Pakistani families communication was primarily two-way, involving the dentist and the child. Parents and families had limited understanding of the process and were unable to offer a comparable level of support that would benefit their children most. This can place additional burdens on the Pakistani child patient and requires a very positive approach from the dental team. CONCLUSIONS: There is a clear need for chairside support, through patient advocates or interpreters, as well as the provision of appropriate educational material to match parents' educational needs on behalf of their children.

Adolescent↗
PubMed1999

Dental beliefs, knowledge and behaviour of Chinese people in the United Kingdom.

OBJECTIVE: This study explored oral health beliefs, knowledge and behaviour among a sample of United Kingdom Chinese. DESIGN: A quota sample of Chinese people, stratified by age and gender, were interviewed by trained and standardised Chinese interviewers using a piloted, validated semi-structured questionnaire. SUBJECTS: One hundred and fifty-six Chinese people--with similar number of teenagers, younger adults and older people--resident in the North East of England. SETTING: Chinese communities. OUTCOME MEASURE: Reported dental knowledge, beliefs and behaviours. RESULTS: Regardless of gender and age, the majority of respondents believed that it was natural for people to lose all their teeth in old age. Less than half were convinced that they would be able to keep their own teeth for life. The majority of the sample considered that they were susceptible to dental diseases, the consequences of which were thought to be serious. Approximately half presumed that dental diseases were preventable, although the aetiology of dental caries, periodontal disease and tooth loss was poorly understood. While 94% claimed to brush their teeth as part of routine dental care, dental visiting and dietary restriction of sugar intake were reported only in 61% and 30% of the sample respectively. Inter-generational differences were marked; older people tended to have a fatalistic attitude and were least likely to attend the dentist. CONCLUSIONS: A low level of dental awareness was found among the UK Chinese. In order to facilitate effective health promotion and treatment services, the extent of Chinese people's traditional oral health beliefs and behaviour must be taken into account.

Adolescent↗
PubMed1998

Attitudes of Chinese people toward obtaining dental care in the UK.

OBJECTIVE: To explore the attitudes of Chinese people regarding dentists and toward obtaining dental care in the UK. INTRODUCTION: Injudicious use of general health services has been reported among Chinese people in the UK. In relation to oral healthcare, the extent to which cultural beliefs and values affect use remains uncertain. SETTING: Chinese communities in the north east of England. SUBJECTS AND METHODS: A quota sample of 156 Chinese people was recruited in 1996. 50 elderly people, 56 adults, 50 teenagers were interviewed by 5 trained and standardised multilingual Chinese interviewers using a validated structured questionnaire. RESULTS: Access varied substantially according to age, with the younger generations more likely to obtain dental care without difficulty. Overall, the sample perceived that dentists possessed adequate technical competence, but their patient management skills lacked sensitivity. Older Chinese people placed less trust in dentists. Many elderly people reported problems in finding a UK dentist and would have preferred one of Chinese origin. Potential problems in follow-up prosthetic dental care were also apparent among this age group. Cost, communication problems, anxiety and cultural beliefs were identified as major barriers to dental care. CONCLUSIONS: There is a clear need to raise cultural awareness among dental professionals as well as to help Chinese people's positive attitudes toward dentists and dental care.

Adolescent↗
PubMed1998

Sedation in primary dental care: an investigation in two districts of northern England.

OBJECTIVE: To determine the current provision of sedation in primary dental care and investigate the knowledge and attitudes of dental practitioners and others on the use of sedation. DESIGN: Qualitative interviews and postal questionnaire survey. SETTING: Health districts of Bradford (West Yorkshire) and South Durham, UK in 1996. SUBJECTS AND MATERIALS: 15 key individuals associated with NHS primary dental services were interviewed. Questionnaires were sent to all 260 NHS general dental practitioners and community dental service clinicians. RESULTS: 208 questionnaires (80%) were returned. 42% of respondents reported current sedation use, with oral administration the favoured technique (26%). Significant differences were found between districts for intravenous sedation use (7% Bradford, 41% South Durham, P < 0.001). Almost all participants agreed the value of sedation in dental care for adults and children, for nervous, phobic patients or in association with unpleasant forms of treatment and 45% of dentists felt that provision should be expanded. Training, availability of referral services, finance and patient demand were seen as encouraging factors. CONCLUSIONS: Substantial variations in sedation provision between the two districts were associated with teaching at the nearest dental schools. Innovative use of resources could help the expansion of provision supported in this study.

Administration, Oral↗
PubMed1998

Thioredoxin peroxidase from Onchocerca volvulus: a major hydrogen peroxide detoxifying enzyme in filarial parasites.

Random screening of an Onchocerca volvulus third-stage (L3) cDNA library identified a highly abundant cDNA encoding a newly discovered antioxidant enzyme, thioredoxin peroxidase (TPx), a member of the peroxidoxin superfamily. This TPx cDNA (Ov-tpx-2) encodes a polypeptide of 199 amino acid residues with a calculated molecular weight of 21,890 Da. The Ov-tpx-2 cDNA represents roughly 2.5% of the total cDNAs from the L3 cDNA library. The gene was expressed in Escherichia coli and the protein product was shown to have antioxidant activity. Antiserum raised against Ov-TPX-2 recognized a native protein from extracts of both the L3 and adult-stages with a molecular weight of 22 kD. The localization and stage-specificity of Ov-TPX-2 protein was analyzed by immunocytochemistry and immunoelectron microscopy using monospecific antibodies. Expression was detected in late first-stage larvae during development in the vector and increased in intensity during differentiation to the infective L3-stage. The antigen was also detected in post-infective larvae and adult worms. In larvae, Ov-TPX-2 protein was predominantly localized to the hypodermis and cuticle, with additional sites in the hypodermal chords and multivesicular bodies. In adult worms, the primary sites of expression were the uterine epithelium and intestine, with additional labeling of the body wall and cuticle. Developing embryos and microfilariae in utero were bathed in Ov-TPX-2 protein discharged from epithelial cells. These results suggest that Ov-TPX-2 may protect the parasites from being damaged by host-generated oxidative stress and that Ov-TPX-2 protein provides the H2O2-detoxifying activity predicted but not previously identified in filarial parasites. Its highly upregulated expression in infective larvae may aid in parasite establishment following transmission to the definitive host.

Amino Acid Sequence↗
PubMed1998

Impairment of the sarcolemmal phospholipase D-phosphatidate phosphohydrolase pathway in diabetic cardiomyopathy.

Experimental evidence suggests that the myocardial phospholipase D (PLD)-phosphatidate phosphohydrolase (PAP) signalling pathway may regulate Ca2+ movements and contractile performance of the heart. As abnormal Ca2+ homeostasis is associated with diabetic cardiomyopathy, we examined the functional status of the PLD/PAP pathway in sarcolemmal (SL) membranes isolated from insulin-dependent diabetic rat hearts at 8 weeks after a single i.v. injection of streptozotocin (65 mh/kg b.w.). Compared to age-matched controls, SL PLD hydrolytic (producing phosphatidic acid, PtdOH) and transphosphatidylation activities were significantly depressed in diabetic animals, while SL PAP was significantly augmented. The net effect of the altered enzyme activities in diabetic animals was a severely diminished (by 67% of controls) membrane level of PLD-derived PtdOH. Two weeks of insulin therapy to the 6 week diabetic animals normalized PLD, while PAP activity and PtdOH level were significantly modified, but had not completely reverted to control values. The observed changes were not due to hypothyroidism associated to the diabetic model as the induction of hypothyroidism in healthy non-diabetic animals did not affect SL PLD and PAP. The results suggest that the severe reduction of PLD-derived PtdOH and increased production of sn-1,2-diacylglycerol by phosphatidate phosphohydrolase may lead to an impairment of the bioprocesses mediated by these signalling lipids.

Animals↗
PubMed1998

Phospholipase A2-mediated activation of phospholipase D in rat heart sarcolemma.

The effect of phospholipase A2 (PLA2)-dependent release of unsaturated fatty acids (FA) on phospholipase D (PLD) function was examined in purified sarcolemmal (SL) membranes isolated from rat heart. PLD hydrolytic activity was determined by measuring either [14C] phosphatidic acid formation from exogenous [14C] phosphatidylcholine (PtdCho) or [3H] choline release from prelabelled SL Ptd[3H]choline. SL membranes with endogenous [3H] PtdCho that were prelabelled with [3H] myristic acid were used for testing PLD transphosphatidylation activity. Exogenous cis-unsaturated FA, arachidonate and oleate, significantly enhanced the [3H] choline formation at 50 and 100 microM, respectively; their effect was maximal at 250 microM and declined at higher concentrations. Use of melittin (which stimulates membrane-bound PLA2, thus releasing FA) or exogenous PLA2 reproduced the stimulatory effect of added arachidonate and oleate. Under melittin, PLA2-dependent FA release was strongly correlated (r = 0.99) to the PLD-dependent phosphatidic acid formation. Arachidonate- or melittin-enhanced PLD transphosphatidylation activity confirmed the augmented catalytic rate of PLD by these agents. Melittin-evoked PLD activation was completely blocked by 1 microM E-6-(bromomethylene) tetrahydro-3-(1-naphthalenyl)-2H-pyran-2-one, a selective inhibitor of Ca(2+)-independent v Ca(2-)-dependent PLA2, thus indicating that PLD stimulation under melittin occurred via PLA2. Activity measurement and Western blotting studies revealed the presence of a Ca(2+)-independent, high molecular weight (110 kDa) PLA2 in the SL membrane, and its immunoprecipitation by monoclonal antibodies significantly reduced the melittin-related PLD stimulation. These results suggest that Ca(2+)-independent PLA2 and subsequent endogenous mobilization of sn-2 unsaturated FA modulate PLD activity in heart SL membranes. This event may occur in physiological conditions via hormonal stimulation of membranal PLA2 as well as in heart diseases characterized by PLA2 pathological dysfunction.

Animals↗
PubMed1998

Quality and care: patients' perceptions.

Patients and health care professionals view quality nursing care from different perspectives. Health care professionals view competent nursing care as quality nursing care. Patients perceive quality nursing care as caring, interpersonal interactions. Institutions measure quality care through satisfaction surveys that exclude components of nurse caring behaviors. In three studies utilizing the Holistic Caring Inventory (HCI), patients perceived nurse caring behaviors and attitudes that indicated quality nursing care. The way to bridge the gap between institutions' and patients' perceptions of quality care lies in valuing the interactions that patients consider quality care and including these interactions in measures of quality care.

Adult↗
PubMed1998

The phytochrome response of the Lemna gibba NPR1 gene is mediated primarily through changes in abscisic acid levels.

Two important signaling systems involved in the growth and development of plants, those triggered by the photoreceptor phytochrome and the hormone abscisic acid (ABA), are involved in the regulation of expression of the NPR1 gene of Lemna gibba. We previously demonstrated that phytochrome action mediates changes in ABA levels in L. gibba, correlating with changes in gene expression evoked by stimulation of the phytochrome system. We have now further characterized phytochrome- and ABA-mediated regulation of L. gibba NPR1 gene expression using a transient particle bombardment assay, demonstrating that regulatory elements controlling responses to both stimuli reside within 156 nucleotides upstream of the transcription start. Linker scan (LS) analysis of the region from -156 to -70 was used to identify two specific requisite and nonredundant cis-acting promoter elements between -143 to -135 (LS2) and -113 to -101 (LS5). Mutation of either of these elements resulted in a coordinate loss of regulation by phytochrome and ABA. This suggests that, unlike the L. gibba Lhcb2*1 promoter, in which phytochrome and ABA regulatory elements are separable, the phytochrome response of the L. gibba NPR1 gene can be attributed to alterations in ABA levels.

Abscisic Acid↗
PubMed1998

The reliability of interview data for age at which infants' toothcleaning begins.

A number of studies have reported on the age at which toothbrushing started and drawn important conclusions. Such studies often relied on parental recall of a particular event that occurred some years previously, assuming the quality of retrospectively reported data. The present study aimed to investigate consistency of reporting the age at which toothcleaning began. Mothers from two different cultural backgrounds, 100 Caucasian and 150 Asian living in a deprived inner city area, were interviewed in their homes on two separate occasions, when the sample child was 6-24 months old and again at 3-4 years. Of the 39 Caucasian and 31 Asian mothers who specified an age at which toothbrushing commenced at both interviews, complete agreement occurred among 4 (10%) Caucasian and 2 (6%) Asian mothers, with a variation of +/- 2 months among 12 (31%) and 5 (16%) respectively. Intraclass correlation coefficients were -0.01 for Caucasian and -0.46 for Asian mothers. Kappa values were 0 and -0.09 respectively. Of the 139 mothers who stated that their children's teeth were not cleaned at the time of the first interview, 17 claimed an earlier age than this at the second interview. It was concluded that there was little agreement between the two interviews, although the extent of the variation differed between the two cultural groups. Although these findings represent relatively deprived population groups, caution is recommended in unquestioningly accepting the accuracy of retrospective reporting of oral hygiene practices in dental surveys until evidence of better reliability is available.

Age Factors↗
PubMed1998

The immunodominant Brugia malayi paramyosin as a marker of current infection with Wuchereria bancrofti adult worms.

The full-length cDNA sequence encoding Brugia malayi L3 paramyosin has been isolated by immunoscreening a cDNA library with a mouse antiserum raised against Wuchereria bancrofti L3 infective larvae. A recombinant truncated form of paramyosin was expressed as a glutathione S-transferase fusion protein and used to evaluate humoral responses of adults from a W. bancrofti-endemic area in French Polynesia according to their parasitological status. Immunoglobulin G4 (IgG4) preferentially bound to paramyosin in W. bancrofti-parasitized individuals, in contrast to unparasitized individuals, who harbored neither microfilaria nor Og4C3 adult worm circulating antigen. Reduction of the anti-paramyosin IgG4 titer following combined chemotherapy with diethylcarbamazine and ivermectin was significantly correlated with a reduction in the adult worm burden. This indicates that the presence of paramyosin-reactive IgG4 is associated with the presence of parasites and that reduction can be used as an immunological marker for W. bancrofti clearance.

Adult↗
PubMed1998

Detection of the filarial parasite Mansonella streptocerca in skin biopsies by a nested polymerase chain reaction-based assay.

To differentiate the skin-dwelling filariae Mansonella streptocerca and Onchocerca volvulus, a nested polymerase chain reaction (PCR) assay was developed from small amounts of parasite material present in skin biopsies. One nonspecific and one specific pair of primers were used to amplify the 5S rDNA spacer region of M. streptocerca. Biopsies with different microfilaria densities obtained from 104 Ugandans living in an area endemic for M. streptocerca were tested using both the nested PCR assay and standard parasitologic assessment of microfilariae. All 82 samples from microfilaria carriers were positive when tested using the nested PCR assay. In addition, M. streptocerca DNA could be detected in 16 samples thought to be microfilaria negative. Furthermore, six days following ivermectin treatment, M. streptocerca DNA was found in 12 of 14 microfilaria-negative biopsies. Control skin samples from patients infected with O. volvulus were all negative in the nested PCR assay. This assay improves the diagnosis of M. streptocerca and will facilitate further epidemiologic studies.

Animals↗
PubMed1997

Subcellular alterations in cardiac phospholipase D activity in chronic diabetes.

Several studies have suggested that myocardial phospholipase D (PLD) and its hydrolytic product, phosphatidic acid (PtdOH), may regulate Ca2+ movements and contractile performance of the heart. Since abnormal intracellular Ca2+ handling is a major factor of myocardial dysfunction in chronic diabetes, we examined subcellular changes in PLD activity in myocardium from insulin-dependent diabetic rats. Diabetes in rats was induced by a single i.v. injection of streptozotocin (65 mg/kg body wt) and 8 weeks later the ventricular tissue was processed for the isolation of sarcolemma, sarcoplasmic reticulum and mitochondria. Compared to age-matched controls, the sarcolemmal, sarcoplasmic reticular and mitochondrial PLD activities were significantly depressed in the diabetic animals. The depressed sarcolemmal PLD activity was normalized, whereas the sarcoplasmic reticular and mitochondrial enzyme activities were partially reversed upon treating the 6-week diabetic rats with insulin for a period of 2 weeks. These data suggest that the reduction of PLD-derived PtdOH may lead to an impairment in this phospholipid signal transduction pathway and subsequent cardiac dysfunction in chronic diabetes.

Animals↗
PubMed1997

Characterization of the 5' flanking region of the human complement factor H gene.

The promoter region of the human factor H gene was cloned and a 3 kb Eco RI fragment was sequenced. Primer extension and S1 nuclease analysis were used to determine the transcription start site, which was found to be 10-11 nucleotides upstream of the published cDNA sequence. No canonical TATA or CCAAT boxes were found in conjunction with this site. The sequence from the human H promoter region was compared to that from the mouse gene. There was a region of 800 bp that was 62.5% identical between the two sequences. The sequences of the two promoter regions were compared to a database of transcription factor binding sites. Five elements were identified that matched the consensus sequence 100% and were identical in the two promoter sequences. Promoter assays using the luciferase reporter gene demonstrated that this region contained a functional transcription start site and putative enhancer elements. U118-MG astroglioma cells and Hep3b hepatoma cells were incubated with various cytokines to measure effects on their factor H mRNA levels. Interferon-gamma (IFN-gamma), but not interleukin-1 (IL-1), tumour necrosis factor alpha (TNF-alpha) or IL-6, was able to increase the level of H mRNA in both cell lines.

Animals↗
PubMed1997

The relationship of patients' perceptions of holistic nurse caring to satisfaction with nursing care.

Hospitalized patients interact with nurses more often than with other health care providers. Qualitative studies have identified patients' and nurses' perceptions of nurse caring behaviors. Few studies have explored nurse caring behavior in relation to patient satisfaction. The article describes a study designed to determine whether there is a relationship between patients' perceptions of nurse caring and satisfaction with nursing care and whether selected patient variables significantly affect that relationship. In the patient population studied, after controlling for patient variables of age, gender, and level of pain, a significant positive relationship was found between patients' perceptions of nurse caring and their satisfaction with nursing care.

Adult↗
PubMed1997

Caring in patient-focused care: the relationship of patients' perceptions of holistic nurse caring to their levels of anxiety.

Holistic nurse caring, also called patient-focused care, is a helping relationship between nurse and patient with the potential to enhance health and healing. Few studies, however, have examined the relationship of the process of nurse caring to patient outcomes. Hospitalized patients face many stressors that cause anxiety. It is known that abnormally high levels of anxiety can interfere with patients' recovery. The article reports a study of patients' perceptions of holistic nurse caring and the relationship of perceptions of caring to levels of anxiety. Patients perceived caring to be evident, and there was a significant relationship between these perceptions and patients' levels of anxiety.

Anxiety↗