Biomedical subjects
Publications and source records attributed to D Williams.
The distinction between active drugs and active biomaterials is being gradually eroded. One of the areas where the interface between drugs and devices needs greater clarity is controlled delivery of drugs by materials and this article discusses the basic mechanisms that are involved.
An increasing number of medical devices are demonstrating better performance if they are used in association with growth factors. This is especially so in the area of tissue regeneration. This article describes the nature of these molecules and discusses some of the issues associated with their incorporation into medical devices.
The properties of a piece of plastic may generally be highly appropriate for a medical application except that its surface may not be optimal. Some of the many ways in which the surfaces of biomaterials can be modified so that the main bulk properties are undisturbed and specialist surface properties exist in a thin, often invisible, layer are described in this article.
The use of gloves when conducting invasive procedures and the reporting of needlestick injuries have been strongly encouraged. Despite this, neither practice appears to be universal. In order to determine the rates of glove usage and needlestick injury reporting, we conducted a survey of junior doctors in three hospitals in the UK. Of the 190 respondents, the majority rarely wore gloves for venesection, insertion of intravenous cannulas or arterial blood gas sampling. For more major procedures (insertion of central venous lines, insertion of thoracostomy tubes, suturing) gloves were invariably worn. Only 17.5% of needlestick injuries were reported. The rates of glove usage and needlestick injury reporting were lower than previous studies have demonstrated in North America. Surgeons suffered the most needlestick injuries and were the least likely to report them. The low reporting rate may have serious implications, particularly in view of the new Government guidelines on needlestick injuries which involve HIV-infected blood. By failing to use gloves and report needlestick injuries, junior doctors, in particular surgeons, are placing themselves and patients at increased risk of blood-borne transmissible diseases.
In last month's column, the workings of the Scientific Committee on Medicinal Products and Medical Devices of the European Commission were discussed and reference was made to a detailed risk assessment that had been undertaken with respect to surgical catgut. This article discusses that assessment.
Risk management is not always straightforward, especially if it has to be based on inadequate data. When the arguments are fuelled by fears for public health, politicians are forced to take difficult decisions and all too frequently it is the scientists who come into the firing line over the provision of advice. This is the first of two articles that addresses some specific issues that relate to risks with medical devices in the context of the European Commission.
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The research related to health care for school-age children is reviewed. Two major categories are considered, namely, health-risk behavior and psychosocial health. Research related to the emerging issues of homelessness and AIDS is also reviewed. The research completed to date on school-age children's health care is critiqued with an emphasis on the state of the science in nursing. Recommendations for further research are provided.
Congenital atresia of the larynx is a rare abnormality. We describe three cases where prenatal diagnosis during the second trimester showed massive abdominal fetal ascites and at post-mortem, laryngeal atresia was identified in two cases, and severe laryngeal stenosis in the third. All were associated with pulmonary hyperplasia. No additional abnormalities were found in other systems. Overdistended lung tissue and ascites are resultant from aberrant laryngeal growth; laryngeal anomalies are a cause of isolated fetal ascites. The association of ascites and voluminous lungs should arouse suspicion of laryngeal atresia and should be an indication for careful pathological study of the fetal larynx.
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A captive-bred adult great horned owl (Bubo virginianus virginianus) behaved as though it was bilaterally blind. An ophthalmological examination showed that it had an increased intraocular pressure in both eyes and gonioscopy showed an abnormality of the iridocorneal angles. Retinal changes were also observed. Treatment was not attempted and the owl was euthanased. Histopathology confirmed the abnormal iridocorneal angles, but the exact aetiology of the primary glaucoma was not identified.
Glucans are (1-->3)-beta-linked glucose polymers which have immune-stimulating capability. The extraction of water-insoluble (1-->3)-beta-D-glucan form Saccharomyces cerevisiae employs hydrochloric acid. Hydrochloric acid is difficult to employ in the large-scale pharmaceutical extraction of glucans due to its corrosive nature and toxicity. To address these concerns, we determined whether acetic, formic or phosphoric acid can be substituted for hydrochloric acid in the process for the isolation of (1-->3)-beta-D-glucan. The resulting microparticulate glucans were employed as the starting material for the production of (1-->3)-beta-D-glucan phosphate. 13C NMR analysis of the glucan phosphates derived from the acetic, formic or phosphoric acid-extracted microparticulate glucan show excellent correspondence to hydrochloric acid extracted glucan and laminarin, a (1-->3)-beta-D-glucan standard, indicating that the primary structure is not altered by the acid used for extraction. Glucan phosphate prepared from hydrochloric acid had a Mw of 7.2 x 10(4) g/mol, rmsz of 17.7 nm, of 1.50 and (eta) of 49.0 mL/g. Glucan phosphate prepared from acetic acid had a primary polymer peak with a Mw of 1.4 x 10(6) g/mol, rmsz of 23.6 nm, I of 1.93 and (eta) of 62.4 mL/g. Glucan phosphate prepared from formic acid had a main polymer peak with a Mw of 1.2 x 10(6) g/mol, rmsz 27.1 nm, I of 1.56 and (eta) of 89.0 mL/g. Glucan phosphate prepared from phosphoric acid had a primary polymer peak with a Mw of 6.6 x 10(5) g/mol, rmsz of 32.3 nm, I of 2.70 and (eta) of 91.3 mL/g. These data indicate that the molecular mass, size, polydispersity and intrinsic viscosity of the glucan phosphate obtained is influenced by the pKa of protic acid employed to extract the microparticulate glucan. However, the primary structure and side-chain branching are not substantially altered regardless of the acid employed.
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PURPOSE: Major burns are associated with a high mortality, an increased rate of bacterial translocation, and bone marrow suppression. This study evaluates the effect of interleukin-11 (IL-11), a bone marrow-derived growth factor on survival, intestinal cytoarchitecture, bacterial translocation, and bone marrow suppression in a highly lethal murine burn model with a lethal dose greater than 50. METHODS: C3H/HeJ 8 to 10-week-old mice underwent a standardized 32% total body surface area (TBSA) scald burn using a burn template. Mice were divided equally between groups receiving IL-11 (125 micrograms/kg, twice daily, subcutaneously [SC]) and 0.1% same-volume Bovine Serum Albumin (BSA) (0.2 mL, twice daily, sc). Animals were evaluated for mesenteric lymph node bacterial counts, intestinal mucosal villus height, number of mucosal crypt cell mitoses per 100 crypts, and peripheral platelet and total lymphocyte counts. Survival was calculated to 7 days postburn. RESULTS: At 24 hours postburn, IL-11-treated mice had significantly less enteric bacteria cultured from mesenteric lymph nodes (P < .001), increased intestinal crypt cell mitoses (P = .002) and intestinal villus height (P = .002), increased peripheral platelet (P = .002) and lymphocyte counts (P = .004), and an improved survival compared with BSA controls (P = .003). CONCLUSION: These data show that IL-11 improves survival, intestinal cytoarchitecture, reduces bacterial translocation, and reduces bone marrow suppression after a 32% TBSA burn in mice. These data imply that IL-11 cytokine therapy may be a useful adjunct in extensive burn injury.
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