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Biomedical subjects

E Richards

Publications and source records attributed to E Richards.

At least 19 recordsLinked to original sources
PubMed2006

Protein cross-contamination during batch cleaning and autoclaving of the ProSeal laryngeal mask airway.

We tested the hypothesis that protein cross-contamination occurs during batch cleaning and autoclaving of a reusable extraglottic airway device, the ProSeal laryngeal mask airway. At the end of each day for 10 days, nine laryngeal mask airways that had been used for non-intra-oral surgery were cleaned and autoclaved alongside a new unused laryngeal mask airway. In addition, a new unused laryngeal mask airway underwent the same cleaning and autoclaving procedures in isolation. Protein staining was more frequently detected on the unused laryngeal mask airways that were processed by batch rather than in isolation (p < 0.01). Protein staining was detected on all unused laryngeal mask airways that were processed by batch, but none on those processed in isolation. Protein staining was more severe with the used compared with the unused laryngeal mask airways (p < 0.001). We conclude that protein cross-contamination of the laryngeal mask airway occurs during batch cleaning and autoclaving and recommend that reusable airway devices are cleaned in isolation.

Cross Infection↗
PubMed2006

High concentration potassium permanganate eliminates protein and particle contamination of the reusable Classic laryngeal mask airway.

In this three-stage study, we test the hypothesis that supplementary cleaning with potassium permanganate > or =4 mg.l(-1) eliminates protein and particle contamination from the reusable Classic laryngeal mask airway. The first stage involved supplementary cleaning of 70 1 x 1 cm segments from deliberately contaminated laryngeal mask airways using potassium permanganate at 0, 2, 4, 8, 16, 32 and 64 mg.l(-1) and testing for protein staining. This showed that the lowest concentration required to eliminate protein contamination was 8 mg.l(-1). The second stage involved supplementary cleaning of 50 used laryngeal mask airways with either potassium permanganate 8 mg.l(-1) or saline and testing for protein staining. This showed that protein contamination was lower in the potassium permanganate group (p < 0.00001): all laryngeal mask airways in the control group and none in the potassium permanganate group were contaminated. The third stage involved scanning electron microscopic examination of 1 x 1 cm segments from three laryngeal mask airways used in the control group, three from the potassium permanganate group, plus three brand new laryngeal mask airways. The mean density of > or =1 mum surface particles was lower in the potassium permanganate 8 mg.l(-1) than the control group (21 vs. 121 .cm(-2), p < 0.0001) and was similar to brand new laryngeal mask airways (24 .cm(-2)). We conclude that supplementary cleaning with potassium permanganate 8 mg.l(-1) eliminates protein deposits from reusable laryngeal mask airways and reduces particle contamination to similar levels to brand new laryngeal mask airways.

Creutzfeldt-Jakob Syndrome↗
PubMed2004

Bulk glasses and ultrahard nanoceramics based on alumina and rare-earth oxides.

Although often regarded as a network-former in conventional silicate glasses, Al(2)O(3) alone cannot be obtained as a bulk glass. Until now, glasses comprising continuously linked [AlO(x)] polyhedra have been prepared in only a few systems under very fast cooling conditions, which limits their dimensions to a few millimetres. Yet it is desirable to prepare bulk, or monolithic, alumina-rich glasses, with the prospect of superior mechanical, chemical and optical properties. Here we report a novel process for preparing very-high-alumina glasses and nanoscale glass-ceramics. Fully dense bulk articles in net shape are obtained through viscous sintering of glass microbeads. Additional heat treatment of the consolidated glasses leads to fully crystallized transparent glass-converted nanoceramics with a hardness similar to that of alumina. This method avoids the impracticably high applied pressures (more than 1 GPa) that have been required in most cases to prepare nanocrystalline ceramics by sintering, owing to the concurrent nature of densification and grain growth under pressureless conditions. The reported techniques can be extended to form glasses and nanoceramics in other oxide systems that do not include a conventional glass-forming component.

Journal Article↗
PubMed2002

Combined spinal epidural anaesthesia for caesarean section: a randomised comparison of Oxford, lateral and sitting positions.

Maternal position during induction of intrathecal anaesthesia for caesarean section influences block height and haemodynamic stability. In a randomised study of 90 women presenting for elective caesarean section using combined spinal-epidural anaesthesia, three positions were compared--the Oxford position (group O), the right lateral to supine wedged (group R) and the sitting to supine wedged (group S). Hyperbaric bupivacaine 12.5 mg with fentanyl 12.5 microg was injected intrathecally using a needle-through-needle CSE technique. Intravenous ephedrine 6 mg was given every minute that systolic blood pressure fell below 80% of baseline. Time required for block height to reach T5 as assessed by light touch, was similar in the three groups. There were no significant differences in blood pressure although ephedrine requirements were less in group R. There were no significant differences in the incidence of maternal nausea and vomiting or in neonatal outcome as assessed by Apgar scores and umbilical cord blood gas analysis. Although the study failed to show any significant differences in block height between the groups, no women in group O had a block above T2 compared with three in group R and three in group S.

Clinical Trial↗
PubMed2001

Asthma, diabetic ketoacidosis and fetal distress.

A known insulin-dependent diabetic parturient at 32 weeks' gestation was treated with oral steroids for presumed exacerbation of asthma. This resulted in maternal ketoacidosis and a non-reassuring fetal heart rate trace for which caesarean section was considered. Cessation of steroids and aggressive management of ketoacidosis resulted in improved maternal and fetal condition without the need for emergency caesarean section.

Journal Article↗
PubMed2001

Avoiding malpractice for nondental conditions. The example of human immunodeficiency virus.

BACKGROUND: Dentists are legally liable for failing to recognize medical conditions that they identify while providing dental care and for failing to refer patients for follow-up care and testing. This article suggests ways to avoid liability using human immunodeficiency virus, or HIV, infection as an example. TYPES OF LITERATURE REVIEWED: The authors conducted a review of the legal literature to determine circumstances that would cause dentists to have legal liability for failing to recognize a medical problem. The authors also conducted a review of the dental literature to identify the most common signs of HIV infection that dentists might see in practice. RESULTS: The legal literature indicates that dentists can be held liable for failing to recognize medical problems, including HIV and acquired immunodeficiency syndrome. The dental literature shows that there are multiple signs and symptoms that indicate the potential for HIV infection to be the underlying cause of many oral diseases. PRACTICE IMPLICATIONS: Dentists should be familiar with the most common oral manifestations of medical conditions that are likely to be identified in the dental office, including those associated with HIV infection. They must recognize medical conditions and arrange for appropriate referral to avoid liability.

AIDS Serodiagnosis↗
PubMed1999

The biological response of MCF7 breast cancer cells to proteosome inhibition or gamma-radiation is unrelated to the level of p53 induction.

The p53 tumour suppressor is stabilised following exposure to genotoxic agents, such as gamma-radiation. Cell responses to p53 stabilisation include induction of apoptosis and/or cell cycle arrest. Several studies have suggested that gamma-radiation stabilises p53 by blocking ubiquitin mediated proteolysis. Here we have compared the biological activities of p53 stabilized following exposure to gamma-radiation or treatment with the proteosome inhibitor N-acetyl-leucinyl-leucinyl-norleucinal (ALLN) in MCF7 cells with wild type p53. Stabilisation of p53 by ALLN was reversible and was not blocked by caffeine. Although ALLN was a more effective p53 stabilising agent than gamma-radiation, ALLN was not as effective at inducing cell cycle arrest/apoptosis as gamma-radiation. Although p53 stabilised by ALLN and gamma-radiation were both able to bind DNA and activate transcription, ALLN did not increase expression of BAX, which is involved in p53-induced apoptosis. Therefore, p53 stabilised by different agents is not always biologically active to the same extent and additional alterations triggered by gamma-radiation may enable p53 to activate a subset of critical target genes, such as BAX, which are required for p53 responses.

Journal Article↗
PubMed1998

Workers for Australia: a profile of British and Irish migrants assisted to New South Wales in 1841.

"This profile of 20,000 British and Irish assisted migrants [to Australia after 1841], based on individual-level data, establishes their age, sex, religious, educational and occupational characteristics. Their composition differed markedly from the existing colonial population and other migrant flows at the time. They reflected the recruiting methods of the time as well as the changing migration propensities in the British Isles. The migrants were better human capital than was acknowledged at the time. They constituted a new start in Australian demographic development."

Age Distribution↗
PubMed1997

Characterization of tumor necrosis factor-deficient mice.

Although tumor necrosis factor (TNF) initially came to prominence because of its anti-tumor activity, most attention is now focused on its proinflammatory actions. TNF appears to play a critical role in both early and late events involved in inflammation, from localizing the noxious agent and amplifying the cellular and mediator responses at the local site and systemically, to editing (e.g., apoptosis) injured cells or effete immune cells and repairing inflammatory damage. We have generated mice deficient in TNF (TNF-/- mice) and have begun to examine the multiple functions attributed to TNF. TNF-/- mice develop normally and have no gross structural or morphological abnormalities. As predicted, they are highly susceptible to challenge with an infectious agent (Candida albicans), are resistant to the lethality of minute doses of lipopolysaccharide (LPS) following D-galactosamine treatment, have a deficiency in granuloma development, and do not form germinal centers after immunization. Phagocytic activity of macrophages appears relatively normal, as do T cell functions, as measured by proliferation, cytokine release, and cytotoxicity. B cell response to thymus-independent antigens is normal, but the Ig response to thymus-dependent antigen is reduced. Surprisingly, cytokine production induced by LPS appears essentially intact, with the exception of reduced colony-stimulating factor activity. Other unexpected findings coming from our initial analysis are as follows. (i) TNF has low toxicity in TNF-/- mice. (ii) TNF-/- mice show an anomalous late response to heat-killed Corynebacterium parvum. In contrast to the prompt response (granuloma formation, hepatosplenomegaly) and subsequent resolution phase in C. parvum-injected TNF+/+ mice, similarly treated TNF-/- mice show little or no initial response, but then develop a vigorous, disorganized inflammatory response leading to death. These results suggest that TNF has an essential homeostatic role in limiting the extent and duration of an inflammatory process-i.e., an anti-inflammatory function. (iii) In contrast to the expectation that TNF+/+ mice and TNF+/- mice would have identical phenotypes, TNF+/- mice showed increased susceptibility to high-dose LPS lethality, increased susceptibility to Candida challenge, and delayed resolution of the C. parvum-induced inflammatory process, indicating a strong gene dose requirement for different actions of TNF.

Animals↗
PubMed1997

Effects of 3,4-methylenedioxymethamphetamine in decomposing tissues on the development of Parasarcophaga ruficornis (Diptera:Sarcophagidae) and detection of the drug in postmortem blood, liver tissue, larvae, and puparia.

Larvae of Parasarcophaga ruficornis (Fabricius) (Diptera: Sarcophagidae) were reared on tissues from rabbits administered different dosages of 3,4-methylenedioxymethamphetamine to study the effects of this drug on the development of this insect species. The rabbits were given 11, 22.5, and 67 mg of the drug via ear vein infusion. These dosages correspond to a 0.5, 1.0, and 2.0 median lethal dose. Larvae from colonies fed on tissues from the rabbit receiving 67 mg and the control developed more rapidly from hours 24 through 114. The period required for completion of larval development was significantly shorter for the larvae from the colony fed on liver tissues from the rabbit receiving the 67 mg dosage. This colony also had the lowest total mortality rate during development. No significant differences were observed among the colonies in the duration of the puparial period. Analyses by liquid chromatography/mass spectrometry of the larvae and empty puparial cases following base extraction detected the drug in quantities directly related to the dosage of the drug administered to the rabbits serving as a food source. These results have implications for the determination of time since death when gauged by the development of this insect species.

Animals↗
PubMed1995

Angiotensin II decreases inducible nitric oxide synthase expression in rat astroglial cultures.

Consistent with stimulation of expression of an inducible form of nitric oxide synthase (iNOS), exposure of rat astroglial cultures to lipopolysaccharide (LPS) caused a time-dependent increase in the accumulation of nitrite in the culture media. Addition of the peptide angiotensin II (ANG II) with LPS decreased subsequent formation of nitrite in a concentration-dependent manner (concentration inhibiting 50% of maximal response approximately 1 nM). The ANG II effect could be blocked by the ANG II type 1 (AT1 receptor antagonist losartan but not by the ANG II type 2 (AT2) receptor antagonist PD-123177. ANG II had no effect on nitrite formation stimulated by a combination of inflammatory cytokines (interleukin-1 beta, tumor necrosis factor-alpha, and interferon-gamma). A brief 10-min exposure to ANG II was sufficient to cause an approximately 30% inhibition of the LPS response, with maximal inhibition of approximately 65% after 3 h, and occurred only when ANG II was added during the iNOS induction phase. Consistent with partial inhibition of LPS-stimulated expression of iNOS, ANG II reduced the levels of both iNOS mRNA and iNOS protein. These results demonstrate that ANG II can decrease LPS-stimulated NO production in astroglia by inhibiting induction of iNOS expression.

Amino Acid Oxidoreductases↗
PubMed1994

Enhanced in vivo growth and resistance to rejection of tumor cells expressing dominant negative IFN gamma receptors.

Using a neutralizing monoclonal antibody specific for murine IFN gamma we show that endogenously produced IFN gamma plays an obligate role in mediating LPS-induced rejection of the Meth A fibrosarcoma tumor in syngeneic BALB/c mice. To examine the cellular targets of IFN gamma action, we generated IFN gamma-insensitive tumor cells by stably overexpressing in Meth A a truncated dominant negative form of the murine IFN gamma receptor alpha chain. When implanted in BALB/c mice, IFN gamma-insensitive Meth A cells displayed enhanced tumorigenicity compared with control Meth A cells and were not rejected when tumor-bearing mice were treated with concentrations of LPS that eliminated control tumors. In Meth A immune mice, IFN gamma-insensitive Meth A did not establish tumors while IFN gamma-insensitive tumors grew in a progressive manner. In addition, the IFN gamma-insensitive tumor cells were unable to elicit strong protective immunity to subsequent wild-type tumor challenge. These results show that IFN gamma has direct effects on tumor cell immunogenicity and thus plays an important role in promoting tumor cell recognition and elimination.

Animals↗