Biomedical subjects
Publications and source records attributed to J Black.
Diabetes mellitus is known to retard wound healing. This study of 35 subjects with pressure ulcers found that carbon dioxide levels were negatively correlated to healing rates. Transcutaneous oxygen levels of peri ulcer was not statistically significantly related to healing rates.
Pressure ulcer repair with skin or muscle flaps may appear to close the wound, but elderly patients need extra precautions before and after surgery to improve the outcome. Nursing care of these patients include monitoring nutrition, removing devitalized tissue from the wound bed, providing proper pressure relief, administering proper patient positioning, and monitoring the flap.
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BACKGROUND: Few studies have assessed the validity or reliability of drinking water intake estimations. In studies investigating potential waterborne disease, this is very important. METHODS: We carried out a validity and reliability study to evaluate water intake estimations. The validity part of the study compared a telephone questionnaire to a diary. The reliability part of the study compared two telephone questionnaires. RESULTS: 253 participants were recruited. The most commonly consumed water intake categories were plain and boiled tap water. For persons aged less than 12 years, the median volume of plain water consumption was 2.9 glasses/day according to the diary. For persons aged 12 years and over, the median volume of plain water consumption was 3.0 glasses/day and for boiled water 3.0 glasses/day according to the diary. There was negligible systematic over or under reporting by participants for the telephone questionnaire in comparison to the diary and for the comparison of both telephone questionnaires. Water intake estimates were converted to categorical variables and the per cent agreement and weighted kappa statistics were calculated. For both the validity and reliability parts of the study the per cent agreement was 57-78% and the weighted kappa was 0.57-0.81. CONCLUSION: Water intake estimates show only moderate levels of validity and reliability when using a telephone questionnaire in comparison to a diary. IMPLICATIONS: Investigators of potential waterborne disease or nutritional research should exercise some caution in drawing conclusions from minor differences in drinking water intake that are obtained from a telephone questionnaire.
OBJECTIVE: To describe an outbreak of Cryptosporidium gastroenteritis in a swimming pool in Melbourne in early 1998 that was not detected through routine surveillance, and discuss difficulties in identifying such outbreaks. METHODS: The Water Quality Study (WQS) was a large community-based study of gastroenteritis. Following suspicion of an outbreak of cryptosporidiosis within the study group, due to pool "X", a nested case control study was performed. Each case of Cryptosporidium gastroenteritis was matched with six controls and data from weekly Health Diaries from the WQS were reviewed. The Department of Human Services also instigated active surveillance among patrons at pool "X" using a systematic sample of 50 people from the pool's swim-school enrollment list. RESULTS: There were seven cases of Cryptosporidium gastroenteritis in the case control study. Five cases and eight controls swam at pool "X" during the outbreak period. The adjusted odds of developing cryptosporidial diarrhoea if an individual swam at pool "X" was 34.5 (CI 2.3-2548). DHS identified another 11 laboratory confirmed cases associated with pool "X" as well as cases not linked to pool "X". 125 cases were identified throughout Melbourne with the suspected involvement of seven swimming pools. CONCLUSIONS: Despite a high odds ratio of developing cryptosporidiosis this outbreak was not detected by routine surveillance methods. Current outbreak detection methods lack sensitivity, specificity or timeliness. IMPLICATIONS: Improved surveillance systems are required if outbreaks of gastroenteritis are to be detected early so an intervention can be instigated to reduce the amount of subsequent illness.
Recent drug regimens have had much success in the treatment of human immunodeficiency virus (HIV)-infected individuals; however, the incidence of resistance to such drugs has become a problem that is likely to increase in importance with long-term therapy of this chronic illness. An analysis and understanding of the molecular interactions between the drug(s) and the mutated viral target(s) is crucial for further progress in the field of AIDS therapy. The protease inhibitor amprenavir (APV) generates a signature set of HIV type 1 (HIV-1) protease mutations associated with in vitro resistance (M46I/L, I47V, and I50V [triple mutant]). Passage of the triple-mutant APV-resistant HIV-1 strain in MT4 cells, in the presence of increasing concentrations of saquinavir (SQV), gave rise to a new variant containing M46I, G48V, I50V, and I84L mutations in the protease and a resulting phenotype that was resistant to SQV and, unexpectedly, resensitized to APV. This phenotype was consistent with a subsequent kinetic analysis of the mutant protease, together with X-ray crystallographic analysis and computational modeling which elucidated the structural basis of these observations. The switch in protease inhibitor sensitivities resulted from (i) the I50V mutation, which reduced the area of contact with APV and SQV; (ii) the compensating I84L mutation, which improved hydrophobic packing with APV; and (iii) the G-to-V mutation at residue 48, which introduced steric repulsion with the P3 group of SQV. This analysis establishes the fine detail necessary for understanding the loss of protease binding for SQV in the quadruple mutant and gain in binding for APV, demonstrating the powerful combination of virology, molecular biology, enzymology, and protein structural and modeling studies in the elucidation and understanding of viral drug resistance.
Two distinct Cl/anion exchange activities (Cl/HCO(3) and Cl/OH) identified in apical membranes of rat distal colon are distributed in cell type-specific patterns. Cl/HCO(3) exchange is expressed only in surface cells, whereas Cl/OH exchange is localized in surface and crypt cells. Dietary Na depletion substantially inhibits Cl/HCO(3) but not Cl/OH exchange. We determined whether anion exchange isoforms (AE) and/or downregulated in adenoma (DRA) are expressed in and related to apical membrane anion exchanges by examining localization of AE isoform-specific and DRA mRNA expression in normal and Na-depleted rats. Amplification of AE cDNA fragments by RT-PCR with colonic mRNA as template indicates that AE1 and AE2 but not AE3 mRNAs are expressed. In situ hybridization study revealed that AE1 mRNA is expressed predominantly in surface but not crypt cells. In contrast, AE2 polypeptide is expressed in basolateral membranes and DRA protein is expressed in apical membranes of both surface and crypt cells. AE1 mRNA is only minimally present in proximal colon, and DRA mRNA abundance is similar in distal and proximal colon. Dietary Na depletion reduces AE1 mRNA abundance but did not alter DRA mRNA abundance. This indicates that AE1 encodes surface cell-specific aldosterone-regulated Cl/HCO(3) exchange, whereas DRA encodes aldosterone-insensitive Cl/OH exchange.
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Injury to the lateral ligaments of the ankle is one of the most common sports-related injuries. Although these injures generally resolve with non-operative treatment reconstruction of the lateral ligaments of the ankle is occasionally necessary. We report the surgical technique and result of reconstruction of the anterior talo-fibular ligament using a semi-tendinosis free graft in 26 patients with an average follow-up of 24 months. 81% of patients reported complete resolution or substantial improvement in instability, swelling and sharp pain. Episodes of functional instability persisted in five patients post operatively. No significant differences were noted between the operated and contra-lateral non-operated ankle in range of motion or uniaxial balance assessment. Kin-Com testing of hamstring strength showed no differences between sides. Short term results suggest that this ligament reconstruction provides good results without sacrifice of peroneal function and has minimal donor site morbidity.
BACKGROUND: Although road traffic accident injury is the most common cause of traumatic brain injury, little is known of the prevalence of psychiatric complications or the significance of unconsciousness and amnesia. AIMS: To describe amnesia and unconsciousness following a road traffic accident and to determine whether they are associated with later psychological symptoms. METHOD: Information was obtained from medical and ambulance records for 1441 consecutive attenders at an emergency department aged 17-69 who had been involved in a road traffic accident. A total of 1148 (80%) subjects completed a self-report questionnaire at baseline and were followed up at 3 months and 1 year. RESULTS: Altogether, 1.5% suffered major head (and traumatic brain) injury and 21% suffered minor head injury. Post-traumatic stress disorder (PTSD) and anxiety and depression were more common at 3 months in those who had definitely been unconscious than in those who had not, but there were no differences at 1 year. CONCLUSIONS: PTSD and other psychiatric complications are as common in those who were briefly unconscious as in those who were not.
BACKGROUND: The importance of particles generated by wear and corrosion of joint replacement prostheses has been understood primarily in the context of the local effects of particle-induced periprosthetic osteolysis and aseptic loosening. We studied dissemination of wear particles in patients with total hip and knee replacement to determine the prevalence of and the histopathological response to prosthetic wear debris in the liver, spleen, and abdominal para-aortic lymph nodes. METHODS: Postmortem specimens from twenty-nine patients and biopsy specimens from two living patients with a failed replacement were analyzed. Specimens of tissue obtained from the cadavera of fifteen patients who had not had a joint replacement served as controls. The concentration of particles and the associated tissue response were characterized with the use of light microscopy of stained histological sections. Metallic particles were identified by electron microprobe analysis. Polyethylene particles were studied with the use of oil-red-O stain and polarized light microscopy. The composition of polyethylene particles was confirmed in selected cases by Fourier transform infrared spectroscopy and hot-stage thermal analysis. Twenty-one of the patients studied post mortem had had a primary total joint replacement. Eleven of them had had a hip prosthesis for a mean of sixty-nine months (range, forty-three to 171 months), and ten had had a knee replacement for a mean of eighty-four months (range, thirty-one to 179 months). The other eight patients studied post mortem had had a hip replacement in which one or more components had loosened and had been revised. The mean time between the initial arthroplasty and the time of death was 174 months (range, forty-seven to 292 months), and the mean time between the last revision procedure and the time of death was seventy-one months (range, one to 130 months). RESULTS: Metallic wear particles in the liver or spleen were more prevalent in patients who had had a failed hip arthroplasty (seven of eight) than in patients who had had a primary hip (two of eleven) or knee replacement (two of ten). The principal source of wear particles in the majority of these patients involved secondary nonbearing surfaces rather than wear between the two primary bearing surfaces as intended. In one living patient, dissemination of titanium alloy particles from a hip prosthesis with mechanical failure was associated with a visceral granulomatous reaction and hepatosplenomegaly, which required operative and medical treatment. Metallic wear particles were detected in the paraaortic lymph nodes in 68 percent (nineteen) of the twenty-eight patients with an implant from whom lymph nodes were available for study. In 38 percent (eleven) of all twenty-nine patients with an implant who were studied post mortem, metallic particles had been further disseminated to the liver or spleen, where they were usually found within small aggregates of macrophages occurring as infiltrates without apparent pathological importance. Polyethylene particles elicited a similar response. They were identified in the paraaortic lymph nodes of 68 percent (nineteen) of the twenty-eight patients and the liver or spleen of 14 percent (four) of the twenty-nine patients. The majority of the disseminated wear particles were less than one micrometer in size. Currently available methods lack the sensitivity and specificity necessary to detect very low concentrations of submicrometer polyethylene particles and probably underestimated the prevalence of polyethylene wear debris in the liver and spleen. CONCLUSIONS: In this study, systemic distribution of metallic and polyethylene wear particles was a common finding, both in patients with a previously failed implant and in those with a primary total joint prosthesis. The prevalence of particles in the liver or spleen was greater after reconstructions with mechanical failure. (ABSTRACT TRUNCATED)
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The flexural-plate-wave (FPW) sensor, a type of ultrasonic sensor, can detect changes in E. coli W3110 concentration in solution as the cells settle onto the sensor under the influence of gravity. A model of the sensor's response to cell settling has been developed and is in good agreement with the experimental data. The FPW technique improves on conventional methods for determining cell concentrations; this technique allows for on-line data collection, is nondestructive, and requires only small sample volumes. The FPW sensor has applications as a device to measure cell concentrations and growth rates in industrial fermentors, biofilms, and wastewater treatment facilities.