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Biomedical subjects

C Dalton

Publications and source records attributed to C Dalton.

At least 19 recordsLinked to original sources
PubMed2006

Fertilization state of Ascaris suum determined by electrorotation.

Electrorotation is a non-invasive technique that is capable of detecting changes in the morphology and physicochemical properties of microorganisms. The first detailed electrorotation study of the egg (ovum) of a parasitic nematode, namely Ascaris suum is described to show that electrorotation can rapidly differentiate between fertilized and non-fertilized eggs. Support for this conclusion is by optical microscopy of egg morphology, and also from modelling of the electrorotational response. Modelling was used to determine differences in the dielectric properties of the unfertilized and fertilized eggs, and also to investigate specific differences in the spectra of fertilized eggs only, potentially reflecting embryogenesis. The potential of electrorotation as an investigative tool is shown, as undamaged eggs can be subjected to further non-destructive and destructive techniques, which could provide further insight into parasite biology and epidemiology.

Animals↗
PubMed2004

An AC electroosmotic micropump for circular chromatographic applications.

Flow rates of up to 50 microm s(-1) have been successfully achieved in a closed-loop channel using an AC electroosmotic pump. The AC electroosmotic pump is made of an interdigitated array of unequal width electrodes located at the bottom of a channel, with an AC voltage applied between the small and the large electrodes. The flow rate was found to increase linearly with the applied voltage and to decrease linearly with the applied frequency. The pump is expected to be suitable for circular chromatography for the following reasons: the driving forces are distributed over the channel length and the pumping direction is set by the direction of the interdigitated electrodes. Pumping in a closed-loop channel can be achieved by arranging the electrode pattern in a circle. In addition the inherent working principle of AC electroosmotic pumping enables the independent optimisation of the channel height or the flow velocity.

Chromatography↗
PubMed2004

Analysis of parasites by electrorotation.

AIMS: The application of the AC electrokinetic technique of electrorotation for studying eukaryotic parasite transmission stages is reviewed. Electrorotation is a noninvasive technique that utilizes electrically energized microelectrode structures within micro-fluidic chambers to probe the physiological structure of micro-organisms. Application of the technique to the transmission life cycle stages of three separate genera of protozoan parasites, Cryptosporidium, Giardia and Cyclospora, and one nematode genus Ascaris, each of significant public health importance, is described. METHODS AND RESULTS: Standard electrorotation apparatus, consisting of micro-fabricated electrodes in a fluidic chip, quadrature sinusoidal signal generator, microscope and image capture system, was used to study each organism. Spectra of cellular rotation rate were recorded as a function of applied electric field frequency and compared with standardized biological tests, where appropriate, to illustrate the effectiveness and versatility of the electrorotation technique. CONCLUSIONS: Electrorotational determination of the viability of individual G. intestinalis cysts, Cryptosporidium parvum and Cyclospora cayetanensis oocysts has been achieved. The sporulation state of Cyclospora cayetanensis oocysts was also readily determined, as was the fertilization state of A. suum ova. SIGNIFICANCE AND IMPACT OF THE STUDY: Electrorotation is a simple, noninvasive and versatile analytical technique suited to a wide range of particle types and capable of incorporation into integrated Lab-on-a-chip devices.

Animals↗
PubMed2004

An open-label pilot study of cannabis-based extracts for bladder dysfunction in advanced multiple sclerosis.

The majority of patients with multiple sclerosis (MS) develop troublesome lower urinary tract symptoms (LUTS). Anecdotal reports suggest that cannabis may alleviate LUTS, and cannabinoid receptors in the bladder and nervous system are potential pharmacological targets. In an open trial we evaluated the safety, tolerability, dose range, and efficacy of two whole-plant extracts of Cannabis sativa in patients with advanced MS and refractory LUTS. Patients took extracts containing delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD; 2.5 mg of each per spray) for eight weeks followed by THC-only (2.5 mg THC per spray) for a further eight weeks, and then into a long-term extension. Assessments included urinary frequency and volume charts, incontinence pad weights, cystometry and visual analogue scales for secondary troublesome symptoms. Twenty-one patients were recruited and data from 15 were evaluated. Urinary urgency, the number and volume of incontinence episodes, frequency and nocturia all decreased significantly following treatment (P <0.05, Wilcoxon's signed rank test). However, daily total voided, catheterized and urinary incontinence pad weights also decreased significantly on both extracts. Patient self-assessment of pain, spasticity and quality of sleep improved significantly (P <0.05, Wilcoxon's signed rank test) with pain improvement continuing up to median of 35 weeks. There were few troublesome side effects, suggesting that cannabis-based medicinal extracts are a safe and effective treatment for urinary and other problems in patients with advanced MS.

Adult↗
PubMed2003

Fresh garlic: a possible vehicle for Salmonella Virchow.

A sustained increase in Salmonella enterica serovar Virchow notifications in South Eastern Australia between September 1997 and May 1998 instigated a case-control study and environmental investigations. Cases were defined as having locally acquired culture-confirmed S. Virchow phage-type 8 infection and diarrhoeal disease. Matched controls were selected by progressive digit dialling based on cases' telephone numbers. An exposure and food history questionnaire was administered by telephone. Phage typing and pulse field gel electrophoresis were performed on case and environmental isolates. Thirty-two notifications of S. Virchow infection met the case definition, 37% reported bloody diarrhoea and S. Virchow was isolated from blood in 13% of cases. Twelve patients were admitted to hospital and one died. Fresh garlic (OR 4.1, 95% CI 1.3-12.8) and semi-dried tomatoes (OR 12.6, 95% CI 1.5-103.1) were associated with these cases. The associations remained significant after adjusting for sex and age. S. Virchow (PT 8) was cultured from two brands of semi-dried tomatoes associated with cases in two different states. We provide sufficient evidence for semi-dried tomatoes and fresh garlic to be considered as potential risk foods in future Salmonella outbreak investigations.

Adolescent↗
PubMed2003

The longitudinal relation between brain lesion load and atrophy in multiple sclerosis: a 14 year follow up study.

BACKGROUND: Studies have suggested that T2 lesion activity is prominent in early relapsing-remitting multiple sclerosis, whereas brain atrophy, while seen early, appears more evident in later progressive disease. The temporal relation between these processes remains unclear. OBJECTIVE: To explore the association between changing brain lesion loads and subsequent tissue atrophy in multiple sclerosis. METHODS: 28 subjects with clinically probable or definite multiple sclerosis (mean age 46.0 years; 17 female and 11 male) were followed for 14 years after first onset of symptoms. T2 lesion loads were estimated soon after symptom onset and at around five, 10, and 14 years later. Disease related atrophy was estimated at the 14 year follow up by comparing brain tissue volumes (proportional to total intracranial volumes) determined in the multiple sclerosis group with data from 29 normal control subjects (mean age 36.7 years; 16 female, 13 male) using multiple linear regression analyses to allow for differences in age and sex distributions. RESULTS: Change in lesion load in the first five years was more closely correlated to disease related brain atrophy at 14 years than later changes in lesion load, although the correlation was only moderate (Spearman correlation = -0.528, p = 0.004). CONCLUSIONS: From this, it appears that early rather than later focal lesion accumulation relates to subsequent brain atrophy, but factors unconnected directly with lesion formation probably also play a significant role in determining such atrophy.

Adult↗
PubMed2002

Precise estimate of fundamental in-vivo MT parameters in human brain in clinically feasible times.

A methodology is presented for extracting precise quantitative MT parameters using a magnetisation-prepared spoiled gradient echo sequence. This method, based on a new mathematical model, provides relaxation parameters for human brain in-vitro and in-vivo. The in-vivo parameters have been obtained from three different regions of normal white matter: occipital white matter, frontal white matter and centrum semiovale; two regions of normal grey matter: cerebral cortex and cerebellum, and from five regions with MS lesions. All this has been achieved using MT images collected within a timeframe that is clinically feasible. We hope that this new technique will shed light on the properties and dynamics of water compartments within the brain.

Brain↗
PubMed2002

Paediatric day stay tonsillectomy service: development and audit.

Day stay paediatric tonsillectomy is well established in many parts of the world but not in Australia. This audit presents the protocol and results of the first one hundred and twenty-five patients managed this way at our hospital. Patients assessed as being at low risk of postoperative complications were offered the procedure as a day patient. All patients had a standardized relaxant anaesthetic technique with an intraoperative opioid and antiemetics. The patients were observed for six hours postoperatively in the Day Stay Unit and contacted the day following surgery to assess any problems. The overall incidence of postoperative vomiting was 15.6%. Two patients required overnight admission. One child was re-admitted on day four for delayed postoperative haemorrhage. Forty-four of the first forty-nine patients' parents were contacted four to six weeks later to assess their experiences of the process. Although approximately three-quarters of the parents rated their child's pain as moderate or severe at some stage, all but one felt the analgesic regimen was good or adequate. Eighty per cent were satisfied with having the surgery as a day stay procedure.

Adolescent↗
PubMed2002

Quantitative 1H MRS imaging 14 years after presenting with a clinically isolated syndrome suggestive of multiple sclerosis.

clinically isolated syndromes (CIS) are events suggestive for emerging multiple sclerosis (MS). A majority of patients develop MS within months or years whilst others remain clinically isolated. The goal of this study was to investigate whether biochemical metabolites detectable by 'H magnetic resonance spectroscopy (MRS) may serve to distinguish between these two groups. We investigated 41 patients 14 years after presentation with a CIS and 21 controls with combined quantitative short echo 'H MRS and magnetic resonance imaging (MRI) and assessed disability according to the Expanded Disability Status Scale (EDSS). At follow-up, 32 had developed MS, and 9 still had CIS. Compared with controls, MS patients demonstrated significantly higher concentrations of myo-inositol (Ins) in normal appearing white matter (NAWM) and lesions. Lesions also demonstrated a reduced N-acetyl-aspartate (NAA) level and an increase in choline-containing compounds (Cho). The NAWM Ins concentration was correlated with EDSS (r = 0.48, p = 0.005). MS normal appearing cortical grey matter (CGM) exhibited a decreased NAA. Patients who remained CIS did not differ significantly from controls in any MRS measure. Metabolite changes in normal appearing white and grey matter in MS indicate diffuse involvement of the entire MS brain, which was not seen in the persisting CIS patients. Elevated Ins in MS NAWM appeared functionally relevant It may indicate glial cell proliferation or gliosis.

Adult↗
PubMed2001

Viability of Giardia intestinalis cysts and viability and sporulation state of Cyclospora cayetanensis oocysts determined by electrorotation.

Electrorotation is a noninvasive technique that is capable of detecting changes in the morphology and physicochemical properties of microorganisms. Electrorotation studies are reported for two intestinal parasites, Giardia intestinalis and Cyclospora cayetanensis. It is concluded that viable and nonviable G. intestinalis cysts can be differentiated by this technique, and support for this conclusion was obtained using a fluorogenic vital dye assay and morphological indicators. The viability of C. cayetanensis oocysts (for which no vital dye assay is currently available) can also be determined by electrorotation, as can their sporulation state. Modeling of the electrorotational response of these organisms was used to determine their dielectric properties and to gain an insight into the changes occurring within them. Electrorotation offers a new, simple, and rapid method for determining the viability of parasites in potable water and food products and as such has important healthcare implications.

Animals↗
PubMed2000

Operation Safe Haven: an evaluation of health surveillance and monitoring in an acute setting.

From May to June 1999, 3,920 ethnic Albanians from Kosovo arrived in Australia as part of Operation Safe Haven. These people were evacuated from refugee camps in the former Yugoslav Republic of Macedonia. Initial processing in Australia occurred at East Hills Reception Centre, and accommodation for the duration of stay was provided in eight Haven Centres in five States. The arrival of a large number of refugees in a short time frame is unprecedented in Australia. A health surveillance system was developed and critical health data were collected to assess health status and needs, plan care, monitor for potential outbreaks of communicable diseases, track service use, to meet international reporting requirements and document our response to this crisis. In this article the health surveillance system is evaluated and suggestions are offered for the formulation of specific guidelines necessary for health surveillance in acute settings.

Acute Disease↗
PubMed1999

Evaluating the potential for opportunistic vaccination in a Northern Territory hospital.

OBJECTIVE: To evaluate the potential for opportunistic vaccination and a simple intervention aimed at improving vaccination coverage for children in hospital. METHODS: Hospital records were reviewed for children under 7 years, discharged from paediatric wards (PW) and the emergency department (ED) for 4 weeks before and after an intervention (423 and 446 children, respectively). This comprised the education of staff and the introduction of prompts to record vaccination status. RESULTS: Documentation of vaccination status increased in the PW (63-90%) and the ED (24-46%), as did the adequacy of detail recorded (51-77% and 8-36%, respectively). Opportunistic vaccination increased from zero of 84 opportunities during the first audit to six of 139 following the intervention. All but one vaccine was given in the PW. Opportunistic vaccination improved when documentation identified a need for vaccination (P = 0. 02). CONCLUSION: There were numerous missed opportunities to vaccinate children in hospital, especially in the ED. Simple prompts improved documentation of vaccination status and the detail of information recorded. Despite improved documentation, opportunistic vaccination failed to improve in the ED. Improving documentation of vaccination status is not sufficient in itself to improve opportunistic vaccination.

Bacterial Vaccines↗
PubMed1998

Community outbreak of psittacosis in a rural Australian town.

BACKGROUND: Health authorities in Victoria, Australia were notified of three men from a rural town with atypical pneumonia, admitted to hospital over 8 days. Initial serological testing suggested Chlamydia psittaci as the cause. We did a case-control study to find risk factors for psittacosis. METHODS: We searched for cases of pneumonia or severe flu-like illness through family physicians and the regional hospital. We selected three controls per case from the region's electoral roll. We collected blood for serological tests and administered questionnaires to all cases and controls. FINDINGS: We found 16 cases of psittacosis and one died. Most cases were clustered within a small geographical area, with a median age of 58 years (range 23-76), 15 (94%) of whom were male. Keeping, handling, or feeding domestic or wild birds was not associated with illness. Cases spent a median of 17.5 h per week in their garden, compared with a median of 5.2 h for controls (p=0.04) and were more likely to have mowed lawns during the 3 weeks before onset of illness than controls (odds ratio 4.81 [95% CI 1.08-33.37]). INTERPRETATION: We showed that psittacosis outbreaks are not limited to direct contact with birds and pose new challenges for disease control. Modifications may be needed to work outdoors to decrease the risk of psittacosis.

Adult↗
PubMed1998

A South Australian Salmonella Mbandaka outbreak investigation using a database to select controls.

UNLABELLED: Between April and June 1996, 15 persons with Salmonella enterica serovar Mbandaka infection were reported in South Australia (population 1.6 million) compared with 12 over the previous five years. To identify a possible source for the infections a case control study was conducted. METHODS: Trained interviewers asked 15 cases and 45 controls about their consumption of 105 foods. Controls were matched to case residential location and age. They were selected from a previously constructed database of 3,014 randomly selected South Australian households. RESULTS: Thirteen of the 15 cases ate 'generic' or 'retail store' brands of peanut butter produced by the same factory in another state, compared with five of the 45 controls (p < 0.01). Salmonella Mbandaka was isolated from three opened jars of peanut butter from case households, and from three unopened jars from retail outlets. Further investigation implicated roasted peanuts from a third Australian state as the source of the Salmonella contamination. DISCUSSION: This is the first recorded outbreak of salmonellosis resulting from the consumption of peanut butter. The SA outbreak investigation comprised a matched case control study to identify possible common food sources. Such investigations need be conducted rapidly to maximise public health benefits, and the utility of selecting controls from a population based database can improve timeliness.

Adolescent↗
PubMed1997

A prolonged outbreak of Campylobacter infection at a training facility.

Campylobacter outbreaks are rarely detected despite Campylobacter being the most common food-borne illness notified to public health authorities. We report a prolonged outbreak of Campylobacter occurring over a three month period at a training facility. Seventy-eight cases were detected, 16 of which were confirmed Campylobacter infections. In seven affected groups of people using the facility, the attack rate ranged between 19% and 67%. An investigation of one sporting group showed that illness was associated with consumption of cucumber served at a self-serve salad bar. Six people attending the facility in other weeks also reported illness after eating only at the salad bar. Transmission of Campylobacter ceased after changes were instituted to food preparation and storage in the facility kitchen.

Adolescent↗
PubMed1997

The gift of time.

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Father-Child Relations↗