Biomedical subjects

S Henderson

Publications and source records attributed to S Henderson.

At least 55 records · Page 3Linked to original sources

PubMed1999

Optical Contrast Variation Study of Nonaqueous Suspensions of Polymer Particles.

We analyze the core-shell structure of sterically stabilized hard sphere polymer colloids by optical contrast variation. Modified polymer particles are used which have the same refractive index as the suspending solvent. At low contrast, inhomogeneities in the core-shell structure of the particles become apparent. The particle form factor is shown to be a sensitive function of the temperature due to the interplay of scattering from the core and the stabilizing layer. We explore the dependence of particle form factors on composition, radius, and temperature and rationalize our observations in terms of a simple core-shell model. By exploiting the sensitivity of the form factors we are able to independently study the two components of a binary mixture of polymer particles. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

Smoking and mental health: results from a community survey.

OBJECTIVE: To assess the relationship of smoking with depression and anxiety symptoms and with risk factors for depression. DESIGN AND SETTING: A community survey conducted in Canberra in 1997. PARTICIPANTS: 2725 persons aged 18-79 sampled from the electoral roll. MAIN OUTCOME MEASURES: Smoking was investigated in relation to psychiatric symptoms (anxiety, depression, alcohol misuse), sociodemographic characteristics (age, sex, education, occupational status), social stressors (divorce, unemployment, financial difficulties, negative life events, childhood adversity), personality (extraversion, neuroticism, psychoticism), and social support (family and friends). RESULTS: Smokers had more depression and anxiety symptoms, more stressors and lower socioeconomic status compared with non-smokers. The association between smoking and psychiatric symptoms persisted even when stressors, socioeconomic characteristics and other factors were statistically controlled. CONCLUSIONS: Smoking is associated with poorer mental health. In helping patients to give up smoking, doctors need to be aware that some may have underlying mental health problems that require attention.

Adolescent↗

PubMed1999

Cognitive abilities in children with congenital muscular dystrophy: correlation with brain MRI and merosin status.

The aim of the study was to evaluate whether children with merosin-positive or merosin-deficient congenital muscular dystrophy (CMD) show any cognitive impairment and whether this is related to brain abnormalities on magnetic resonance imaging (MRI). Twenty-two patients (age range: 5.8-15.3 years) were assessed by the Wechsler Intelligence Scales. Twelve were merosin-positive and ten merosin-deficient. One child had severe mental retardation and could not be tested. The full scale IQ in the remaining 21 ranged from 51 to 134, the verbal IQ ranged from 78 to 136 and the performance from 51 to 136. Of the twelve children with normal merosin one had a mild delay (IQ < 75) and two were borderline (IQ 75-95). Of the ten children with merosin-deficiency, one showed severe mental retardation and could not be tested, one showed a mild delay and two had borderline results. While the children with merosin deficiency with the typical diffuse white matter changes on MRI had normal scores, the children who in addition had cerebellar hypoplasia had lower performance IQ. The child with cortical dysplasia had severe mental retardation. Our results suggest that the spectrum of cognitive abilities in CMD is very wide even within genetically homogeneous conditions.

Adolescent↗

PubMed1999

Attitudes towards people with a mental disorder: a survey of the Australian public and health professionals.

OBJECTIVE: The aim of this paper was to compare the Australian public's attitudes towards people who have been treated for a mental disorder with the attitudes of general practitioners, psychiatrists and clinical psychologists. METHOD: The study involved a household survey of 2031 members of the Australian public and a postal survey of 872 general practitioners, 1128 psychiatrists and 454 clinical psychologists. Survey participants were presented with a vignette describing a person with schizophrenia or one with depression. They were asked opinions about the person's long-term outcome in various areas of life after receiving treatment. Participants were also asked whether they thought the person described would be discriminated against by others. RESULTS: Both the public and professionals rated outcomes as poorer and discrimination as more likely for the person with schizophrenia than for the one with depression. The professionals made more negative ratings than the public, although the clinical psychologists had similar attitudes to the public about depression. CONCLUSIONS: Compared to the public, health professionals rate long-term outcomes more negatively and discrimination as more likely. It is possible that these more negative attitudes are realistic, being based on greater knowledge of mental disorders. However, professional attitudes may be biased by greater contact with patients who have chronic or recurrent disorders. Either way, health professionals need to be aware of the effects that their negative attitudes might have on patients and the public.

Adolescent↗

PubMed1999

Genotyping as a diagnostic aid in genetic haemochromatosis.

BACKGROUND: Two mutations in a newly described gene, HFE, have been proposed as genetic markers for the inherited iron overload disease, genetic haemochromatosis. METHODS: We assessed the frequency of both mutations in a cohort of genetic haemochromatosis patients and compared these with a control population. The patients were genetic haemochromatosis patients from Western Australia whose diagnosis met strict criteria for phenotypic expression. Control patients had other liver disease where iron overload was excluded. RESULTS: Genomic DNA of 72 genetic haemochromatosis patients and 69 controls was examined for the C282Y and H63D mutations of the HFE gene using polymerase chain reaction amplification and restriction enzyme digestion. In genetic haemochromatosis patients, the C282Y mutation was homozygous in 64 of 72, giving a sensitivity of 89% (95% confidence interval 82-96%), heterozygous in five (7%) and absent in another three (4%), whereas none of the control subjects were homozygous. The H63D mutation was present in one genetic haemochromatosis patient and was not useful as a diagnostic marker. In this cohort of Western Australian patients with phenotypic expression of genetic haemochromatosis, the specificity of a homozygous C282Y mutation for genetic haemochromatosis was 100%. CONCLUSIONS: The results indicate that genotyping for the C282Y mutation is a useful test for the diagnosis of genetic haemochromatosis in clinical practice.

Amino Acid Substitution↗

PubMed1999

Motor and perceptual-motor competence in children with Down syndrome: variation in performance with age.

The aim of this study was to determine whether perceptual-motor competence in school-age children with Down syndrome was generally delayed or varied as a function of type of action. Twenty-two children with Down syndrome (13 males, 9 females), aged between 4.5 and 14 years were assessed on two standardized tests, the Movement Assessment Battery for Children (Movement ABC), a test of motor competence assessing gross and fine motor coordination, and on the Developmental Test of Visual-Motor Integration, a test focusing on shape copying. In order to obtain a profile of each child's performance on the different items contained in the Movement ABC, the test was used in its extended form. This involves testing any child who failed an item appropriate for his/her level, at progressively lower levels until a base-line measure was obtained. All the children obtained scores below the 5th percentile for their age on both tests. However, superimposed on this delay, we found distinct variation as a function of task. Whereas some aspects of gross motor function showed age development with delayed but regular acquisitions, all the aspects of fine motor skills assessed were more severely impaired and showed little development with age. Accuracy and timing of tasks requiring bimanual coordination were most impaired in our sample while balance and ball skills showed more variability. These results suggest that intervention in the motor domain should be varied according to each child's particular profile of performance.

Adolescent↗

PubMed1999

Congenital hemiplegia in children at school age: assessment of hand function in the non-hemiplegic hand and correlation with MRI.

The aim of this study was to evaluate whether children with congenital hemiplegia show abnormal hand function on the non-hemiplegic side and whether this, if present, can be related to the type and extent of brain lesions on MRI. Twenty-two children with congenital hemiplegia of age ranging between 4.8 and 12.3 years, were assessed with a clinical and MRI assessment. Clinical assessment included a structured neurological examination, assessment of hand grips and the Movement Assessment Battery for Children which also includes one item assessing speed and accuracy in each hand. The results showed that 64% of the children studied showed some degree of functional impairment of the non-hemiplegic hand. Manual dexterity 1 from the Movement ABC was, in our experience, a more sensitive tool to detect minor functional abnormalities than the evaluation of hand grips. The severity of the impairment on the non-hemiplegic side was not significantly related to the severity of impairment in the hemiplegic hand (p > 0.05). In contrast, a significant association was found with the site of lesions as hand function in the non-hemiplegic hand was always normal in children with unilateral lesion and abnormal in the ones with bilateral parenchymal lesions (p < 0.05). Children with predominantly unilateral lesions but with bilateral ventricular dilatation or periventricular changes showed more variable results.

Brain↗

PubMed1999

Detection of Chlamydia trachomatis and Neisseria gonorrhoeae in swab specimens by the Hybrid Capture II and PACE 2 nucleic acid probe tests.

BACKGROUND AND OBJECTIVES: The Digene Hybrid Capture II (HC II) CT/GC Test (Digene Corp., Beltsville, MD) is a new nucleic acid signal amplification-based test for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae in specimens from the genital tract. For optimal results, the HC II CT/GC Test employs a special conical shaped brush for cervical specimen collection from nonpregnant women and swabs from pregnant women. GOALS: To validate a protocol for HC II C. trachomatis and N. gonorrhoeae testing of specimens collected for the GenProbe PACE 2 System. STUDY DESIGN: Specimens were collected from 1,746 patients with a swab and placed in GenProbe transport media according to the manufacturer's recommended procedure. The specimens were first tested at two clinical laboratories by the PACE 2 system, and then blindly tested by HC II CT/GC using an adjusted cutoff value. Discrepant specimens were adjudicated by polymerase chain reaction (PCR), and the result common to two of the three testing methods (HC II, PACE 2, and PCR) was defined as the consensus result. RESULTS: Combining the data from both sites, the relative sensitivity of the HC II Test compared with the consensus result for the detection of 1,761 specimens for C. trachomatis and 1,750 specimens for N. gonorrhoeae was 100% for both organisms. The relative specificities for C. trachomatis and N. gonorrhoeae detection were 99.8% and 99.7%, respectively. The relative sensitivities of the PACE 2 CT and GC Systems were 86.5% and 87.1%, respectively, with relative specificities of 99.9% and 100%. The difference in sensitivity between HC II and PACE 2 for C. trachomatis detection was significant (P < 0.016). CONCLUSION: The HC II CT/GC Test can be performed using specimens collected in GenProbe transport media and has a significantly greater sensitivity for C. trachomatis detection than the PACE 2 System.

Cervix Uteri↗

PubMed1999

Frames of reference utilized in the rehabilitation of individuals with eating disorders.

An occupational therapist's role with clients diagnosed with eating disorders, both anorexia nervosa and bulimia nervosa, has been described throughout the literature. However, the frames of reference and treatment approaches that occupational therapists implement have not been clearly established or validated. This paper outlines the symptomatology of anorexia nervosa and bulimia nervosa, and critically reviews the current literature concerning the frames of reference and treatment approaches used by occupational therapists when intervening with this population. The literature reviewed indicates that therapists are using a variety of frames of reference and treatment approaches. There appears to be an emphasis on the psychoanalytical and cognitive-behavioural frames of reference, although there is a lack of empirical evidence in regards to all frames of reference and treatment approaches. Reasons for the lack of current research with this population, and possible future areas of research are suggested.

Anorexia↗

PubMed1999

Cost comparison of antibacterial therapies for serious infections. A New Zealand 3-hospital study.

OBJECTIVE: The first aim was to identify and determine the economic costs of the regimens currently used in 3 New Zealand hospitals in the treatment of bacterial infections in haematology patients with febrile neutropenia and in intensive care patients with severe infections. The second was to develop a spreadsheet-based decision analytic model for use by hospital decision-makers as an aid in evaluating the comparative cost of drug regimens. DESIGN AND SETTING: The research utilised time and motion and microcosting techniques. The analytical perspective adopted for the study was that of a hospital administrator or clinical manager. PATIENTS AND INTERVENTIONS: Patients were eligible for inclusion in the study if either they were treated with the imipenem/cilastatin monotherapy, or could have been treated with this regimen. The final analysis considered 360 patient-treatment days and 8 antibacterials. MAIN OUTCOME MEASURES AND RESULTS: Drug acquisition cost ranged from 4.52 New Zealand dollars ($NZ; 1997 values) per patient-treatment day for gentamicin to $NZ104.81 for imipenem. The cost per patient-treatment day (when other cost components such as fluid additives, giving sets and needles were added) ranged from $NZ8.75 for gentamicin to $NZ129.12 for tazobactam. Drug acquisition cost, as a percentage of total drug preparation and administration cost, ranged from 52% for gentamicin to 93% for piperacillin. Giving sets and intravenous (i.v.) fluids were found to be important cost items when they were required specifically for the treatment regimen. There was a mean monitoring rate of 0.40 at a cost of $NZ6.41 per patient-treatment day for gentamicin. It was estimated that nephrotoxicity could add between $NZ23 and $NZ43 per day to the cost of aminoglycoside treatment. CONCLUSIONS: Although the small sample sizes of the study mean that results should be regarded as indicative rather than conclusive, there were sufficient information to construct a working model and show how the total cost of an antibacterial regimen could be evaluated in practical terms. The important cost drivers were found to be drug cost, the use of fluids and giving sets, and monitoring.

Anti-Infective Agents↗

PubMed1998

Distinct mutants of retrograde intraflagellar transport (IFT) share similar morphological and molecular defects.

A microtubule-based transport of protein complexes, which is bidirectional and occurs between the space surrounding the basal bodies and the distal part of Chlamydomonas flagella, is referred to as intraflagellar transport (IFT). The IFT involves molecular motors and particles that consist of 17S protein complexes. To identify the function of different components of the IFT machinery, we isolated and characterized four temperature-sensitive (ts) mutants of flagellar assembly that represent the loci FLA15, FLA16, and FLA17. These mutants were selected among other ts mutants of flagellar assembly because they displayed a characteristic bulge of the flagellar membrane as a nonconditional phenotype. Each of these mutants was significantly defective for the retrograde velocity of particles and the frequency of bidirectional transport but not for the anterograde velocity of particles, as revealed by a novel method of analysis of IFT that allows tracking of single particles in a sequence of video images. Furthermore, each mutant was defective for the same four subunits of a 17S complex that was identified earlier as the IFT complex A. The occurrence of the same set of phenotypes, as the result of a mutation in any one of three loci, suggests the hypothesis that complex A is a portion of the IFT particles specifically involved in retrograde intraflagellar movement.

Animals↗

PubMed1998

Colorectal cancer screening by general practitioners: comparison with national guidelines.

OBJECTIVE: To determine whether general practitioners (GPs) had received Australian guidelines on early detection, screening and surveillance for colorectal cancer or rectal bleeding, and whether their reported practice conformed with these guidelines. DESIGN: Cross-sectional postal survey of self-reported practice. PARTICIPANTS AND SETTING: 213 GPs in practice in the southern metropolitan area of Perth, Western Australia, were randomly selected from the Fremantle Regional Division of General Practice database and surveyed in March 1997. RESULTS: Replies were received from 155 (73%) of the GPs, and 110 reported receiving guidelines (from the Australian Gastroenterology Institute [AGI], 44; Gut Foundation of Australia [GFA], 40; others, 6; and not specified, 20). GPs who reported receiving guidelines were significantly more likely to screen for colorectal cancer (99/110; 90%) than those who reported not receiving guidelines (33/45; 73%) (P = 0.008). The commonest method to investigate people with identifiable risk factors for colorectal cancer was colonoscopy. Reported screening frequencies in asymptomatic patients with above-average risk (family history of colorectal cancer or past history of adenomatous polyps or colorectal cancer) were significantly higher than recommended by AGI and GFA guidelines (P < 0.05). Up to 24% of GPs investigated altered bowel habit or bleeding per rectum with faecal occult blood testing. CONCLUSIONS: Most GPs report having received guidelines. Reported screening frequency was higher than recommended for most above-average-risk patients, which will result in excessive consumption of resources without benefits for cancer prevention.

Adult↗

PubMed1998

Variations in referral pattern for postoperative radiotherapy of patients with screen-detected breast cancer in the south Thames (east) region.

This paper describes the findings of a region-wide audit undertaken in 1995-1996 of post-operative radiotherapy treatment for patients with screen-detected breast cancer. The study covers the first 3 years from the start of the South Thames (East) Breast Screening Programme in June 1988 up to March 1992. The audit shows that only 60% of the patients with invasive carcinoma who were treated by conservation surgery are known to have received radiotherapy. A considerable variation in referral patterns was observed across the region. Analysis suggests that whilst geographical, patient choice and tumour factors may play an important role in the selection of patients for radiotherapy treatment after conservative surgery for early breast cancer, management protocols of surgical units were the most critical factor, and that these appear to vary, depending on the level of involvement of the clinician with the screening programme (as measured by case-load).

Breast Neoplasms↗

PubMed1998

Notch/LIN-12 signaling: transduction by regulated protein slicing.

Intercellular signaling through the Notch/LIN-12 transmembrane receptors regulates growth and differentiation during animal development. Moreover, defects in the conserved Notch/LIN-12 pathway are linked to human diseases. Here, we review models for two key steps in Notch/LIN-12 signaling: ligand-mediated activation of the receptor and receptor-mediated activation of transcription. Ligand binding appears to permit proteolysis of the receptor; as a result, the receptor's intracellular domain can enter the nucleus and function as a transcriptional co-activator.

Animals↗

PubMed1998

Priapism following trazodone overdose with cocaine use.

Priapism is a urologic disorder and medical emergency with a variety of known etiologies including the use of psychotropic medications. The antidepressant trazodone is the agent most frequently implicated in the precipitation of priapism. Additionally, a number of drugs of abuse including marijuana, ethanol, and cocaine have been known to cause the disorder. It is unknown if drugs may act in an additive or a synergistic manner to cause priapism. We report a case of priapism which occurred following trazodone overdose in an individual actively using cocaine. This case suggests that combined trazodone and cocaine use may pose an additional risk of priapism. Since trazodone is commonly employed as a hypnotic and often chosen for polysubstance abusers due to its low abuse potential, clinicians should be aware of the possible additive risk of priapism in this patient population.

Adult↗

PubMed1998

Mutations in fibroblast growth-factor receptor 3 in sporadic cases of achondroplasia occur exclusively on the paternally derived chromosome.

More than 97% of achondroplasia cases are caused by one of two mutations (G1138A and G1138C) in the fibroblast growth factor receptor 3 (FGFR3) gene, which results in a specific amino acid substitution, G380R. Sporadic cases of achondroplasia have been associated with advanced paternal age, suggesting that these mutations occur preferentially during spermatogenesis. We have determined the parental origin of the achondroplasia mutation in 40 sporadic cases. Three distinct 1-bp polymorphisms were identified in the FGFR3 gene, within close proximity to the achondroplasia mutation site. Ninety-nine families, each with a sporadic case of achondroplasia in a child, were analyzed in this study. In this population, the achondroplasia mutation occurred on the paternal chromosome in all 40 cases in which parental origin was unambiguous. This observation is consistent with the clinical observation of advanced paternal age resulting in new cases of achondroplasia and suggests that factors influencing DNA replication or repair during spermatogenesis, but not during oogenesis, may predispose to the occurrence of the G1138 FGFR3 mutations.

Achondroplasia↗

PubMed1998

Prevention of antigen-induced microtubule organizing center reorientation in cytotoxic T cells by modulation of protein kinase C activity.

Lysis of target cells (TC) by cytotoxic T lymphocytes (CTL) is achieved by directional exocytosis of cytolytic molecules-perforin and granzymes. They are stored within lytic granules which can be readily released following antigenic stimulation. Secretion of lytic molecules appears to be controlled by protein kinase C (PKC) activity, since specific modulators of PKC activity abolish the lysis of TC. We have examined the effect of PKC modulation on some of the earliest events in the perforin/granzyme-mediated cytotoxicity. De novo synthesis of perforin mRNA, required for the refilling of granules and sustained cytotoxicity, seems to be unaltered in the presence of PKC modulators. Immunofluorescent studies of CTL-TC conjugates revealed that PKC modulation impairs reorientation of the microtubule organizing center toward the contact point with the TC, which accounts for the specific direction of lytic granules exocytosis. Thus, it appears that PKC regulates exocytosis of lytic granules by governing microtubule reorganization, one of the initial steps in perforin/granzyme-mediated cytotoxicity.

Animals↗

PubMed1998

Epidemiology of dementia.

With an unprecedented demographic change in the world population, the prevention and effective treatment of age-dependent diseased has become a compelling need. Epidemiology contributes in this way by estimating the incidence and prevalence of specific categories of morbidity and by identifying the risk or protective factors of dementia. An integrative analysis of 47 surveys across 17 countries has suggested approximate rates under 1% for dementia from any cause in persons aged 60 to 69 years, rising to about 39% in persons 90 to 95 years old. The prevalence doubles with every five years of age within that range, with few differences taking into account secular changes, age, gender, place of living... Risks factors of vascular dementia are well known. Worldwide epidemiological surveys allow to differentiate "confirmed risk factors" of Alzheimer's type dementia (age, family history, Apolipoprotein E epsilon 4 genotype and Down's syndrome), "possible risk factors" (head injury, aluminum, previous depression...) and "protective factors" (education, anti-inflammatory drugs and estrogen replacement...).

Aged↗