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Biomedical subjects

A Lewis

Publications and source records attributed to A Lewis.

At least 109 records · Page 6Linked to original sources
PubMed1997

Vitreoretinal surgery assisted by the 193-nm excimer laser.

PURPOSE: Ablating and cutting vitreoretinal membranes using a 193-nm excimer laser-based microsurgical system. METHODS: A 193-nm microsurgical system enables delivery of the beam into a fluid medium to cut preretinal and subretinal membranes. Two patients with proliferative diabetic retinopathy and one patient with proliferative vitreoretinopathy were treated with this new device. RESULTS: Gentle ablation and cutting of the preretinal and subretinal membranes without exerting any traction on or apparent damage to the neighboring tissue was achieved. CONCLUSIONS: The technology is applicable to a variety of intraocular vitreoretinal surgical procedures.

Aged↗
PubMed1996

Passive immune globulin therapy in the SIV/macaque model: early intervention can alter disease profile.

One of the major questions in AIDS is the role that the host immune system and the virus play in the dynamics of infection and the development of AIDS in an infected individual. In order to test the role of antibody in controlling viral infection, high-dose SIV-immune globulin was passively transferred to infected macaques early in infection. Immune globulin purified from the plasma of an SIV-infected long-term non-progressor macaque (SIVIG) or a pool of normal immune globulin (normal Ig) was infused into SIVsmE660-infected macaques (170 mg/kg) at one and fourteen days post infection. Animals were monitored for SIV-specific antibodies, viremia, plasma antigenemia, and clinical course. All animals were infected by SIV. At 16 months post infection, five macaques in the combined control groups have been euthanized, one as a rapid progressor with debilitating disease at 20 weeks post infection. Four macaques from the comparison groups have signs of AIDS, accompanied by high and increasing levels of virus and p27 antigenemia. One of the ten control animals had a very low virus load in plasma and peripheral blood and lymph node mononuclear cells at all times tested and has remained disease-free. In the SIVIG treatment group, two macaques were euthanized at 18-20 weeks due to AIDS, rapid progressors to disease. Three macaques in the SIVIG group had an initial high level of virus in plasma, peripheral blood mononuclear cells (PBMC), and lymph node mononuclear cells (LNMC), which dropped to baseline at 6 weeks post infection and has remained very low or negative for 16 months, a disease profile which has not been observed in untreated animals in this model to date. These macaques have remained clinically healthy. The sixth treated animal is also healthy, with very low virus burden that is detectable only by nested set polymerase chain reaction (PCR). All SIVIG-treated macaques had no detectable p27 plasma antigenemia for the first 10 weeks of infection, demonstrating that the IgG effectively complexed with the virus. The immunological correlates in the treated animals include development of de novo virus-specific antibodies and/or cytotoxic T cell (CTL), both of which are hallmarks of long term non-progressors. The two SIVIG-treated macaques that progress to disease rapidly had no detectable de novo humoral immune responses, as is often seen in rapid HIV disease in humans. Envelope-specific and virus neutralizing antibodies alone were not sufficient to prevent disease progression, as the plasma of both non-progressors as well as progressors had high titers of envelope-specific and neutralizing antibodies against SIVsmE660. Poor clinical prognosis was associated with moderate to high and increasing virus loads in plasma, PBMC, and lymph nodes. Good clinical prognosis correlated with low or undetectable post acute viremia in the peripheral blood and lymph nodes. We hypothesize that SIVIG reduced the spread of virus by eliminating or reducing plasma virus through immune complexes during the first four to 8 weeks of infection and then maintaining this low level of viremia until the host immune response was capable of virus control. Reduction of virus burden early in infection by passive IgG can alter disease outcome in SIV infection of macaques. Modifications of this strategy may lead to effective early treatment of HIV-1 infection in humans.

Animals↗
PubMed1996

Infrared nonlinear optical measurements of membrane potential in photoreceptor cells.

In the past it has not been possible to measure optically the membrane potential of cells and collections of cells that are either naturally photosensitive or that can be activated by photolyzable caged transmitter molecules. This paper reports on a unique application of nonlinear optics that can monitor the potential of cellular membranes with a near-infrared source. Among many other singular advantages, this nonlinear optical approach to measuring membrane potential does not activate light sensitive cells or cell suspensions and cellular networks surrounded with photolyzable molecules. To demonstrate this capability we show that the technique can be applied to living photoreceptor cells that are very sensitive to visible light. These cells are ideal for characterizing such a new technique, not only because of their unmatched sensitivity to light, but also because their electrical responses have been extensively characterized (Minks and Selinger, 1992).

Animals↗
PubMed1996

Directly probing rapid membrane protein dynamics with an atomic force microscope: a study of light-induced conformational alterations in bacteriorhodopsin.

This paper demonstrates that an atomic force microscope can be used to directly monitor rapid membrane protein dynamics. For this demonstration the membrane-bound proton pump, bacteriorhodopsin, has been investigated. It has been unequivocally shown that the light-induced dynamic alterations that have been observed do not arise from external artifacts such as heating of the sample by the incident light, but that these changes can be directly linked to the light-induced protein conformational alterations in this membrane. In essence, it has been shown that the light energy absorbed by bacteriorhodopsin is converted not only to chemical energy but also to mechanical energy. In summary a new ultrasensitive tool is described for monitoring the molecular dynamics of materials with wide applicability to fundamental and applied science.

Bacteriorhodopsins↗
PubMed1996

Interaction, language and the "narrative turn" in psychotherapy and psychiatry.

The traditional emphasis in psychiatry about "listening to patients" has recently been added to by the development of what we call the "narrative turn" in mental health care where clients' narratives are emphasised. We shall argue however that both approaches tend to embody similar assumptions about therapeutic transactions and roles, and that much work emphasising narratives reveals little about how therapists and researchers work to reconstruct the clients' accounts. It is therefore vital that the emphasis on narratives be supplemented by a more thoroughgoing approach to shared structures of knowledge which act to prefigure clients' distress, how professional records are a profoundly transformative medium, and how therapeutic encounters work to co-construct clients' narratives, rather than simply reflect or explore them. The radical implications of thinking about therapy in terms of narrative and language need to be more fully discussed in the therapy literature, so the narrative turn does not simply reproduce the common-sense assumptions of more conventional approaches.

Communication↗
PubMed1996

No-fault liability--twenty years experience in New Zealand.

In 1974 the New Zealand Government enacted the Accident Compensation Act to make provision for the rehabilitation and compensation of persons who suffer personal injury by accident. It abolished actions for damages arising directly or indirectly out of personal injury by accident and death resulting therefrom. In 1992 this Act was replaced by the Accident Rehabilitation and Compensation Insurance Act. This paper examines the problems which arose from the implementation of the first Act and the reasons for the latest Act.

Accidents, Occupational↗
PubMed1995

The role of water in retinal complexation to bacterio-opsin.

A system is described that allows for the delineation of the factors that effect the complexation of retinal to the apoprotein of bacteriorhodopsin. This complexation is investigated in various states of hydration, in H2O and D2O, at a variety of pH levels, with mutant membranes and labeled retinals. The complexation reaction was also investigated using absorption spectroscopy and vibrational spectra using difference Fourier transform infrared spectroscopy. The results demonstrate the crucial role of water in controlling the protein conformations that lead to protein/ligand binding reactions and begin to shed new light on the protein control of a reaction that normally cannot take place in an aqueous medium.

Bacteriorhodopsins↗
PubMed1995

Haematological and acute-phase responses associated with delayed-onset muscle soreness in humans.

Delayed-onset muscle soreness following unaccustomed or eccentric exercise is associated with inflammation, tissue necrosis and the release of muscle enzymes (Newham et al. 1983). We have investigated the time course of changes in circulating leucocytes and serum levels of some acute phase reactants, serum creatine kinase activity (CK) and muscle pain after a 40-min bout of bench-stepping exercise in eight healthy untrained subjects. Leg muscle soreness was greatest 2 days after the exercise bout. Peak serum CK values [mean (SD) 540 (502) IU.1-1] occurred 1-7 days post-exercise. Serum C-reactive protein (CRP) was unchanged from pre-exercise levels [7.8 (3.4) mg.1-1] immediately post-exercise [7.9 (2.3) mg.1-1] but rose to a peak of 17.0 (3.9) mg.1-1 1 day post-exercise, thereafter declining to basal levels. Serum levels of iron and zinc fell below pre-exercise levels for 1-3 days post-exercise. Serum albumin, IgG and IgM fell below pre-exercise levels from 1 day post-exercise, reaching minimal values (about 80% of basal levels) at 7 days post-exercise. The exercise did not appear to significantly affect serum levels of alpha-1-antitrypsin and alpha-1-acid glycoprotein. Two and three days after the exercise bout the circulating numbers of total leucocytes, neutrophils, monocytes and basophils fell 15-20% below pre-exercise levels, whereas lymphocytes, eosinophils and platelets were unchanged. The results indicate that a rapid acute phase inflammatory response is initiated within 1 day of a bout of exercise that induces delayed-onset muscle soreness, and that any later tissue necrosis that may occur is not accompanied by further marked changes in acute-phase reactants such as CRP.

Acute-Phase Proteins↗
PubMed1995

Psychiatric morbidity and psychodynamics of patients with convulsive pseudoseizures.

Forty-six female patients with pseudoseizures were compared with 50 female patients referred to a psychiatric outpatient clinic. Patients with convulsive pseudoseizures were more likely to be single and childless. An abnormal EEG was more frequently reported in patients with convulsive pseudoseizures, contributing to their earlier diagnosis of epilepsy. The defence mechanisms of patients with convulsive pseudoseizures using the Defense Mechanisms Inventory (DMI) were particularly characterized by higher scores on the 'reversal' scale and lower scores on the 'turning against self' scale. Mood disorders were more common in general psychiatric patients, while one-third of convulsive pseudoseizure patients did not complain of psychiatric symptoms.

Comorbidity↗
PubMed1995

Cost of pressure ulcer prevention in long-term care.

OBJECTIVE: To describe the total cost of pressure ulcer prevention, component costs of each intervention, and the relationship of costs to subjects' risk level. DESIGN: 3-month cohort trial. SETTING: A 600-bed, state-supported, long-term care facility. PATIENTS: A total of 539 war veterans, 83% of whom were male; mean age was 73 years. MAIN OUTCOME MEASURES: Cost to facility for using each of four preventive interventions: turning, pressure-reducing mattresses, chair cushions, miscellaneous preventive devices. RESULTS: Sixty-eight percent of subjects received a preventive intervention. Total 3-month facility cost of prevention was $132,114, and 97% of the cost was consumed by 30% of the subjects. Turning was the most expensive component, accounting for $99,567. The daily cost of turning for subjects who received it was $8.83 +/- 1.66. Cost increased with subject risk level. Low cost devices were instituted for lower risk subjects, whereas high cost interventions (turning) were reserved for the highest risk subjects. CONCLUSIONS: This long-term care facility expended substantial resources on prevention, and most resources (97%) were expended on less than half (30%) of subjects. Turning was, by far, the most expensive intervention, and the nursing staff reserved it for highest risk subjects. Strategies that substitute moderately priced mattresses for frequent turning may decrease the cost of prevention, as long as mattress cost is less than the daily turning costs it replaces. Future research to define the optimum combinations of preventive interventions for patients of various risk levels is needed.

Aged↗
PubMed1995

The taps project. 29: residential care provision in north London: a representative sample of ten facilities for mentally ill people.

Described are ten residential facilities, which represent examples of different residential arrangements available for mentally-ill people in a north London region. Administrative issues, daily routine, physical layout, and other aspects regarding residents and staff are addressed. The environmental features of the facilities were rated by using structured assessments. The facilities, though run by various agencies and providing different levels of care, demonstrate a common set of principles and practices, which formulates a framework for successful care. Generally, there has been no indication of any shortcomings in providing a reliable and good standard of care.

Humans↗