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Biomedical subjects

R Green

Publications and source records attributed to R Green.

At least 73 records · Page 4Linked to original sources

Approaching translation at atomic resolution.

Atomic resolution structures of 50S and 30S ribosomal particles have recently been solved by X-ray diffraction. These ribosomal structures show often unusual folds of ribosomal RNAs and proteins, and provide molecular explanations for fundamental aspects of translation. In the 50S structure, the active site for peptide bond formation was localized and found to consist of RNA. The ribosome is thus a ribozyme. In the 30S structures, tRNA binding sites were located, and molecular mechanisms for ribosomal fidelity were proposed. The 30S subunit particle has three globular domains, and relative movements of these domains may be required for translocation of the ribosome during protein synthesis. The structures are consistent with and rationalize decades of biochemical analysis of translation and usher in a molecular age in understanding the ribosome.

Models, Molecular↗

Hybrid system for telepathology.

We introduce a novel hybrid telepathology system providing simultaneous transmission of both real-time microscopy and static imagery at a reasonable cost. It is capable of capturing static, true color images at resolution of 1,520 x 1,144 pixels and providing live transmission of real-time video images of the glass slide in Common Intermediate Format (CIF), which can be viewed at 1,024 x 768 pixels or higher. Instant freeze function can be enabled with 4x CIF resolution (1,408 x 1,152 pixels). This system comprises the advantages of real-time transmission and high-resolution static imagery, while direct visual and audio communications are maintained at the same time. It uses standard 'off-the-shelf' components with a total cost of around $30,000 to $40,000. We also conclude that differences in telepathology modality and image quality have an impact on diagnostic accuracy and should be considered for discussion and standards development by professional organizations in the field of telepathology. An effort to ascertain the diagnostic limitations of various telepathology modalities is essential to the future use of this modality of pathology practice.

Computers↗

The number of CD34+ cells mobilized into the peripheral blood can predict the quality of subsequent collections.

PBPC were mobilized using a variety of chemotherapy regimens plus G-CSF in a group of 126 consecutive patients. Data are presented that show a close correlation between the number of CD34+ cells mobilized into the peripheral blood (PB) and the number of CD34+ cells subsequently collected by leukapheresis (R = 0.904). On the basis of this correlation, a regression formula was calculated that could give an estimate of the total number of CD34+ cells likely to be collected by leukapheresis from a given number of CD34+ cells per microliter PB. An easy-to-read table has been compiled to show how this type of analysis can be applied to predict the likely dose of CD34+ cells that will be obtained by leukapheresis over a wide range of patient weights.

Antigens, CD34↗

Primary and metastatic diseases in malignant melanoma of the gastrointestinal tract.

In this review, the gastrointestinal (GI) manifestations of malignant melanoma including primary mucosal melanoma of the GI tract and metastatic melanoma to the GI tract are discussed. Although malignant melanoma most commonly arises in the skin, primary melanomas can also arise from the mucosal epithelial lining of the gastrointestinal tract. The vast majority of gastrointestinal melanoma is metastatic from a cutaneous primary; however, there is evidence that melanoma can arise de novo from within certain areas of the gastrointestinal system. The sporadic nature and small numbers of patients reported in the literature with mucosal melanomas have prevented a good understanding of the pathogenesis, natural history, and optimal treatment of this uncommon presentation of melanoma.

Diagnosis, Differential↗

Open houses and closed rooms: Tokelau housing in New Zealand.

The migrant Tokelau community in New Zealand, through the Wellington Tokelau Association, is playing an active role in partnership with the Wellington School of Medicine to develop a research program to help improve the health of its people. The relationship between crowded homes and health was investigated in six focus groups. While cultural patterns were an essential part of Tokelau hospitality, the decision to "double up" households was often the result of "rational" economic decision making in relation to household expenditures such as rent and food. The implication for public health practitioners is that while overcrowding may be a health hazard for residents, the most effective solutions by the community are higher household income and more flexible housing designs that accommodate multifamily households.

Asian↗

Eosinophils in asthma and other allergic diseases.

A hallmark of allergic disease is infiltration of the tissues with increased numbers of eosinophils. This is the result of the co-ordinated action of cytokines, particularly IL-5, CCR3 binding chemokines and the adhesion molecules P-selectin and VCAM-1, acting in concert to cause selective trafficking of eosinophils into allergic tissue. This process is orchestrated by the Th-2 allergen specific lymphocyte. While there is little data to support the view that eosinophils ameliorate the allergic process, although they could have an important role in the disordered repair that leads to permanently impaired function in some allergic diseases, the evidence that they cause many of the pathophysiological features of allergic disease, while strong, remains circumstantial. Much of the data could be interpreted just as easily to suggest that eosinophils are bystander cells; markers of a certain type of pathological process, but not impinging upon it. The most direct evidence for a pathological role rests on the toxicity of the eosinophil granule proteins for bronchial epithelium and the bronchoconstrictor actions of the sulphidopeptide leukotrienes. The actions of LT antagonists in asthma which are certainly beneficial, but in most cases are not as effective as glucocorticoids, could be interpreted both for and against the eosinophil. In this paper we have focused on the studies that ask most directly the question of whether eosinophils are important effector cells in the pathogenesis of allergic disease. We conclude with a qualified affirmative. Even if they are only bystander cells they remain clinically important as diagnostic markers and a guide to the management of allergic disease.

Antibodies, Monoclonal↗

Quality of information on hospice referral.

Good quality referral information provides hospice staff with essential information at a time when patients are particularly vulnerable. An Ideal Referral Criteria tool for measuring the quality of general practitioners' information was piloted at one hospice site. Overall inter-rater reliability was 90%, with individual categories ranging from 19% to 34%. Cronbach's alpha was 0.35. Further psychometric testing is recommended.

Family Practice↗

Gastric lavage for liquid poisons.

STUDY OBJECTIVE: This study was conducted to determine whether gastric lavage reduces the absorption of ingested liquids. METHODS: The study design was a randomized controlled human volunteer crossover study in 10 subjects. On 2 separate occasions 2 weeks apart, the volunteers ingested a solution of 4.0 g of acetaminophen in 60 mL of water. Eight blood specimens were obtained over the initial 8 hours for determination of serum acetaminophen concentrations, which were used to calculate routine pharmacokinetic parameters. One hour after 1 drug ingestion, gastric lavage was performed through a 34-F orogastric tube. Serum acetaminophen concentrations were measured by high-performance liquid chromatography and a 2-tailed t test was used for statistical analysis. RESULTS: The mean values for area under the concentration curve (+/-SD) for the control and gastric lavage groups were 195+/-31 and 154+/-52 mg/L.hour, respectively (P <.05). The mean reduction in acetaminophen bioavailability because of gastric lavage was 20%+/-28% (95% confidence interval 3 to 37). CONCLUSION: In this experimental model for the ingestion of liquids, gastric lavage at 1 hour resulted in a significant decrease in the mean serum bioavailability of acetaminophen. Nonetheless, this treatment effect is unlikely to be of clinical value because of its modest extent, unreliable performance, and the availability of a more effective, less risky alternative, activated charcoal.

Acetaminophen↗

Guideline for the management of chronic asthma in children--2000 update. Allergy Society of South Africa Working Group.

OBJECTIVE: To increase awareness of asthma and diagnose asthma early in children. To make recommendations regarding management of chronic childhood asthma in a country with diverse cultural, socio-economic and educational characteristics. The guideline should be used by health professionals involved in the treatment of asthma at all levels of care. OPTIONS: Various management options were considered. Ideal treatment includes use of the new generation inhaled corticosteroids (fluticasone, budesonide), housedust mite intervention for asthma control using impermeable covers for pillows and mattresses, and if needed use of inhaled long-acting beta 2 agonists (LABAs) and leukotriene receptor antagonists (LRAs). Alternative therapeutic approaches for situations where resources are limited include simple housedust mite control measures (e.g. airing mattresses and bedding), avoidance of exposure to passive smoking, use of lower doses of beclomethasone than recommended by other guideline documents and/or sustained-release (SR) theophylline as preventer treatment and use of plastic bottles as cheap spacer devices. OUTCOMES: The main potential outcomes considered were: to reduce morbidity and mortality by correct diagnosis of asthma, to achieve the best quality of life for the child with asthma, to minimise side-effects from medication and to prevent development of permanently abnormal lung function. EVIDENCE: Current international guideline documents for diagnosis and management of childhood asthma were evaluated. Clinical studies before 1998 pertaining to the various aspects of management of childhood asthma were reviewed, including controlled studies on the use of inhaled corticosteroids in children with asthma, randomised controlled trials on the use of LRAs and two studies evaluating the efficacy of LABAs. Current data on the anti-inflammatory effects of SR theophylline were also reviewed as well as a randomised controlled trial on the benefits of SR theophylline as adjunct treatment in childhood asthma. The benefit of simple spacer devices, based on well-conducted local studies (published in an international peer-reviewed journal) was also considered. VALUES: The South African Childhood Asthma Working Group (SACAWG) committee members, appointed by the Allergy Society of South Africa (ALLSA), were selected to represent the interests of health professionals involved in the care of childhood asthma and to co-opt other colleagues with expertise relevant to the guideline. The committee was divided into six task groups headed by a chairperson--each task group had to review critically the previous SACAWG guideline (for deficiencies and obstacles to implementation), review current trends in asthma management (evidence-based where available) and submit proposals and recommendations to their respective chairperson. The chairperson then compiled a report for discussion by the SACAWG executive committee. The executive group convened a meeting to discuss the recommendations and obtain consensus. An editorial board was appointed to compile the final report. Cultural factors, patient preferences, cost, availability and education were considered important. BENEFITS, HARMS AND COSTS: Proper treatment should enable most children with asthma to lead normal or near-normal lives. The guideline could be implementable at all levels of care. The risk of systemic effects due to inhaled corticosteroids should be minimised in children with mild to moderate persistent asthma (risk of systemic effects is more likely at daily beclomethasone doses exceeding 400 micrograms or the equivalent dose of other inhaled corticosteroids). Promotion of simple environmental control measures and use of inhaled beclomethasone and/or SR theophylline should make treatment more widely available and more affordable and improve adherence to treatment. Alternative cheap plastic bottle spacer devices will increase availability and assist with overcoming the problem of incorrect inha

Adrenal Cortex Hormones↗

Efficient 50S ribosome-catalyzed peptide bond synthesis with an aminoacyl minihelix.

RNA minihelices that recreate the amino acid acceptor domain of the two-domain L-shaped tRNA molecule are substrates for specific aminoacylation by tRNA synthetases. Some lines of evidence suggest that this domain arose independently of and predated the second, anticodon-containing domain. With puromycin and a minihelix charged with alanine, we show here efficient 50S ribosome catalyzed peptide synthesis. The aminoacyl minihelix is as active as aminoacyl tRNA in the synthetic reaction. The high efficiency of the charged minihelix is due to a relatively strong interaction with the 50S particle. In contrast, an aminoacyl RNA fragment that recreates the 3'-side of the tRNA acceptor stem has a much weaker interaction with the 50S particle. These results are consistent with the minihelix domain being the major loci for tRNA interactions with the 50S ribosome. They may also have implications for the historical development of RNA-based systems of peptide synthesis.

Acylation↗