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Biomedical subjects

R Stafford

Publications and source records attributed to R Stafford.

At least 19 recordsLinked to original sources
PubMed2006

Frequency of infectious gastrointestinal illness in Australia, 2002: regional, seasonal and demographic variation.

To estimate the frequency of infectious gastroenteritis across Australia, and to identify risk factors, we conducted a national telephone survey of 6087 randomly selected respondents in 2001-2002. The case definition was three or more loose stools and/or two or more vomits in a 24-hour period in the last 4 weeks, with adjustment to exclude non-infectious causes and symptoms secondary to a respiratory infection. Frequency data were weighted to the Australian population. Multivariate logistic regression was used to assess potential risk factors including season, region, demographic and socioeconomic status. Among contacted individuals, 67% responded. The case definition applied to 7% of respondents (450/6087) which extrapolates to 17.2 million (95% CI 14.5-19.9 million) cases of gastroenteritis in Australia in one year, or 0.92 (95% CI 0.77-1.06) cases/person per year. In the multivariate model, the odds of having gastroenteritis were increased in summer and in the warmest state, in young children, females, those with higher socioeconomic status and those without health insurance.

Adolescent↗
PubMed2004

Retinally-generated saccadic suppression of a locust looming-detector neuron: investigations using a robot locust.

A fundamental task performed by many visual systems is to distinguish apparent motion caused by eye movements from real motion occurring within the environment. During saccadic eye movements, this task is achieved by inhibitory signals of central and retinal origin that suppress the output of motion-detecting neurons. To investigate the retinally-generated component of this suppression, we used a computational model of a locust looming-detecting pathway that experiences saccadic suppression. This model received input from the camera of a mobile robot that performed simple saccade-like movements, allowing the model's response to simplified real stimuli to be tested. Retinally-generated saccadic suppression resulted from two inhibitory mechanisms within the looming-detector's input architecture. One mechanism fed inhibition forward through the network, inhibiting the looming-detector's initial response to movement. The second spread inhibition laterally within the network, suppressing the looming-detector's maintained response to movement. These mechanisms prevent a looming-detector model response to whole-field visual stimuli. In the locust, this mechanism of saccadic suppression may operate in addition to centrally-generated suppression. Because lateral inhibition is a common feature of early visual processing in many organisms, we discuss whether the mechanism of retinally-generated saccadic suppression found in the locust looming-detector model may also operate in these species.

Animals↗
PubMed2000

Three nursing home outbreaks of Norwalk-like virus in Brisbane in 1999.

We report on three nursing home outbreaks of gastroenteritis in Brisbane in 1999. The presence of Norwalk-like virus (NLV) genogroup 2 was demonstrated by reverse transcription polymerase chain reaction (RT-PCR) in all three outbreaks. Common findings of these investigations were rapid spread of the illness within the institutions and difficulties in identifying a common source. Nursing home populations are vulnerable and it is important for each institution to have infection control policies in place so outbreaks can be managed promptly. This includes the exclusion of ill staff for 48 to 72 hours after recovery from illness. Genogrouping of NLV by RT-PCR can take several days so control measures will generally have to be instituted before results become available.

Adult↗
PubMed2000

A community outbreak of Cryptosporidium infection associated with a swimming pool complex.

A case-control study was conducted to investigate the cause of a sudden increase in cases of cryptosporidiosis notified to the Brisbane Southside Public Health Unit from January to March 1998. Fifty-two eligible cases were identified over a three-week period early in 1998. Thirty-one of these cases and 21 control subjects participated in the study. Swimming in the 2 weeks before onset of illness was identified as a likely risk factor for cryptosporidiosis infection (OR 3.1, CI 0.8-12.6, P = 0.06). Analysis of swimming pool attendance identified swimming at Pool Complex A as a significant risk factor for the acquisition of cryptosporidiosis (OR 8.9, CI 1.5-67.4, P = 0.004). No other potential risk factors were significantly associated with illness. The detection of cryptosporidium oocysts in three of the four pools at Pool Complex A supported the findings of the case-control study. As a response to this outbreak, Queensland Health has developed a Code of Practice outlining measures for the control and prevention of future outbreaks of swimming pool-associated cryptosporidiosis and/or giardiasis.

Adolescent↗
PubMed2000

An outbreak of multi-resistant Shigella sonnei in a long-stay geriatric nursing centre.

An outbreak of Shigella sonnei infection in a long-stay nursing centre was detected during routine surveillance of notifications in July 1999. Subsequent investigations identified 13 cases of multi-resistant S. sonnei infection affecting nine staff, three community members associated with the centre and one resident of the centre. Each isolate of S. sonnei was genetically indistinguishable. The outbreak investigation identified contact with residents with vomiting and diarrhoea as a significant risk factor for infection amongst staff providing nursing care. This association, and the duration of the outbreak over several months, suggests that transmission was most likely person-to-person. This outbreak demonstrates the importance of infection control policies and hygiene measures in long-stay nursing facilities.

Aged↗
PubMed1999

An outbreak of Salmonella typhimurium at a teaching hospital.

An outbreak of Salmonella typhimurium infection in December 1996 affected 52 patients, relatives, and staff of a large teaching hospital in southeast Queensland. Assorted sandwiches were identified as the vehicle of transmission. This article describes the outbreak investigation and demonstrates the importance of food hygiene and timely public health interventions.

Adolescent↗
PubMed1999

Trauma faculty and trauma team activation: impact on trauma system function and patient outcome.

OBJECTIVE: To determine the impact of the presence of an attending trauma surgeon during trauma team activation on system function and patient outcome. METHODS: After a retrospective review of medical records and trauma registry, a comparative study between two American College of Surgeons Committee on Trauma Level I trauma centers was performed. One center (Hennepin County Medical Center) required a chief surgical resident, two junior residents, and a board-certified emergency medicine faculty to be present in the emergency department for all trauma team activations. The attending trauma surgeon was notified at the time of trauma team activation and was neither required to be present in the emergency department at time of patient arrival nor in the hospital 24 h/day. The other center (St. Paul Ramsey Medical Center) required a chief surgical resident, two junior residents, a board-certified emergency medicine faculty member, and an attending trauma surgeon to be present in the emergency department for all trauma activations and in hospital 24 hours/day. Over a 21-month period, all major trauma patients (Injury Severity Score > 15 or emergent operation within 4 hours of admission and any Injury Severity Score) that triggered trauma team activation were examined. Resuscitation time, time to incision, probability of survival, and mortality were analyzed. RESULTS: Resuscitation time was shorter at St. Paul Ramsey Medical Center when compared with Hennepin County Medical Center. Analysis by mechanism of injury demonstrates that this was true for blunt trauma (39+/-13 vs. 27+/-12 minutes, p = 0.001) and for penetrating trauma (28+/-14 vs. 24+/-17 minutes, p = 0.01). Subgroup analysis of penetrating trauma victims demonstrated that there was a significant difference in resuscitation times for gunshot wounds but not for stabs. There was no difference in how quickly operations could be initiated for blunt trauma patients. However, in penetrating cases, time to incision was significantly shorter at St. Paul Ramsey Medical Center (50+/-29 vs. 66+/-43 minutes, p = 0.01). There was no significant difference in mortality for any category of Trauma and Injury Severity Score probability of survival in blunt or penetrating trauma. Analysis of "in-house" and "out-house" time intervals demonstrated no difference in survival in any mechanism of injury, nor was there a difference in overall mortality. CONCLUSION: The presence of a trauma surgeon on the trauma team reduced resuscitation time and reduced time to incision for emergent operations, particularly in penetrating trauma. However, it had no measurable impact on mortality based on Trauma and Injury Severity Score probability of survival. Attending trauma surgeon presence on the trauma team improves in-hospital trauma system function without affecting patient outcome.

Adult↗
PubMed1999

The duration of ambulatory visits to physicians.

BACKGROUND: The objective of our study was to determine the typical length of ambulatory visits to a nationally representative sample of primary care physicians, and the patient, physician, practice, and visit characteristics affecting duration of visit. METHODS: We used an analysis of cross-sectional survey data to determine duration of visit and the characteristics associated with it. The data sources were a random sample of the 19,192 visits by adults to 686 primary care physicians contained in the 1991-1992 National Ambulatory Medical Care Survey, and the results of the Physician Induction Interview conducted by the National Center for Health Statistics. Duration of visit was defined as the total time spent in face-to-face contact with the physician. RESULTS: Mean duration of visit was 16.3 minutes (standard deviation = 9.7). Multivariate analysis allowed the calculation of the independent effect on visit length of a variety of characteristics of patients, physicians, organizational/practice setting, geographic location, and visit content. Certain patient characteristics (increasing age and the presence of psychosocial problems) were associated with increased duration of visit. Visit content was also associated with increased duration, including ordering or performing 4 or more diagnostic tests (71% increase), Papanicolaou smears (34%), ambulatory surgical procedures (34%), patient admission to the hospital (32%), and 3 preventive screening tests (25%). Reduced duration of visit was associated with availability of non-physician support personnel and health maintenance organization and Medicaid insurance. CONCLUSIONS: Multiple factors affect duration of visit. Clinicians, policymakers, and health system managers should take these considerations into account in managing physician resources during daily ambulatory practice.

Adult↗
PubMed1997

An outbreak of Norwalk virus gastroenteritis following consumption of oysters.

In August 1996, an outbreak of Norwalk virus gastroenteritis occurred among south-east Queensland and northern New South Wales residents over a four week period. Ninety-two of the 97 cases detected were confirmed as having consumed raw oysters within three days prior to developing the illness. No other food items or beverages were significantly associated with the illness. Environmental investigations indicated the Terranora Broadwater, Tweed Heads as the origin of the contaminated oysters. However, the primary source of Norwalk virus could not be verified. Oysters and other shellfish appear to be a common vehicle for transmission of this virus. This outbreak and the more recent hepatitis A outbreak associated with Wallis Lake oysters, highlight the susceptibility of oysters to environmental contamination and the urgent need for stricter quality control procedures. This report details the epidemiological, microbiological and environmental findings from an outbreak investigation conducted jointly by the Queensland and New South Wales health authorities.

Adolescent↗
PubMed1997

Experimental simulation of the thrust phases of fast-start swimming of fish

Measurements of the thrust and forward impulse of a simulated fish tail and mathematical modeling indicate that the propulsive forces of fast-start swimming can be optimized by three different effects: (i) exactly inverting the tail tip vortex that is generated with the initial stroke, (ii) using a moderately flexible tail, and (iii) introducing a specific delay between the initial stroke and the return stroke. Experiments were performed with a new computer-controlled fish-tail simulation apparatus, and the results confirm the theoretical predictions of a previous study.

Journal Article↗
PubMed1996

Does storage of sputum specimens adversely affect culture results?

It has been recommended that samples submitted for microbiological examination should be retained for 48 hours after issue of the final report. In order to ascertain whether reproducible results could be achieved following storage of sputum specimens, two laboratories each re-cultured 100 samples 48 hours after their report had been issued and a further laboratory re-cultured 100 samples 48 hours after receipt. Discordant results were obtained in only 5-25% of specimens, indicating that potential respiratory pathogens could survive storage.

Bacteriological Techniques↗
PubMed1994

Cytokines, neuropeptides, and reperfusion injury during magnesium deficiency.

In summary, hypomagnesemia enhances reperfusion injury. We postulate that neurogenic inflammation, which occurs very early during hypomagnesemia, predisposes the myocardium to reperfusion injury by depleting endogenous antioxidants and recruiting inflammatory cells, which can participate in enhanced free radical production during postischemic reperfusion. Vitamin E supplements can prevent the occurrence of this enhanced injury possibly through the restoration of endogenous antioxidant defenses.

Animals↗
PubMed1994

Loss of red blood cell glutathione during Mg deficiency: prevention by vitamin E, D-propranolol, and chloroquine.

Mg deficiency results in loss of red blood cell glutathione and was thought to be due to decreased Mg-dependent synthesis. The effects of vitamin E, D-propranolol, and chloroquine on red blood cell glutathione levels in Mg-deficient rats were examined. Feeding the rats a Mg-deficient diet for 3 wk resulted in an approximately 80% decrease in serum Mg and a 55% loss of red blood cell glutathione; concomitantly, plasma thiobarbituric acid reactive (TBAR) materials rose 240%. All three drug treatments had no effect on the plasma Mg levels but significantly inhibited the rise in TBAR content and attenuated (60-80% effective) the loss of glutathione. Red blood cell ghost membranes from the Mg-deficient rats also exhibited 2.3-fold higher TBAR content, which was attenuated by vitamin E treatment. With isolated red blood cells from Mg-sufficient rats, loss of glutathione could be induced by a chemical oxyradical system. Direct protective effects were afforded by alpha-tocopherol and D-propranolol but not by chloroquine. The data suggest that 1) the loss of glutathione during Mg deficiency was due to increased oxidative degradation, 2) both vitamin E and D-propranolol protected by a membrane antiperoxidative action, and 3) chloroquine probably protected by diminishing prooxidant activity secondary to its inhibition of cytokine induction during Mg deficiency.

Animals↗
PubMed1994

Patient outcomes. Are they linked to registered nurse absenteeism, separation, or work load?

Using a correlation design, the authors explored the possible associations between patient outcomes and staff registered nurse absenteeism, separation from the work unit, and work load. Data analysis included a search for consistent patterns of relationships across acute care hospitals and over time. Nosocomial urinary tract and bloodstream infections correlated positively with absenteeism. The authors discuss clinical and methodological issues related to the findings.

Absenteeism↗
PubMed1992

Effect of vehicle on skin penetration and retention of a lipophilic red tide toxin (PbTx-3).

The purpose of this study was to determine the effect of carrier vehicle on the penetration of brevetoxin ([3H]PbTx-3) into skin layers and receptor fluid. Disks of guinea-pig skin were mounted on penetration chambers. Epidermal surfaces were dosed with 0.320 microgram/cm2 of PbTx-3 dissolved in 50 microliters of vehicle [water, methanol, or dimethylsulfoxide (DMSO)]. In vitro skin penetration by PbTx-3 during 24 hr of exposure was 6.2, 2.3 and 26% for water, methanol, and DMSO, respectively (expressed as % of dose applied).

Animals↗
PubMed1983

Relapse of antibiotic associated colitis: endogenous persistence of Clostridium difficile during vancomycin therapy.

This study reports 24 patients with antibiotic associated colitis due to Clostridium difficile. Fifteen patients were treated with vancomycin due to the severity of the colitis and in eight of these a clinical relapse of the colitis occurred after vancomycin therapy was stopped. Bacteriological investigations of these patients indicated that C difficile was able to persist in stool samples during vancomycin therapy in the absence of detectable cytotoxin. This was in contrast with the seven patients successfully treated with vancomycin without relapse, and those not treated with vancomycin where both stool cultures and cytotoxin assays became negative. These results suggest that patients being treated with vancomycin for antibiotic associated colitis due to C difficile should have stool cultures done during and after treatment. Persistence of the organism in the absence of detectable cytotoxin may identify those patients who relapse and lead to either recommencement of vancomycin or alternative therapeutic approaches.

Adolescent↗