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Biomedical subjects

A Lewis

Publications and source records attributed to A Lewis.

At least 163 records · Page 9Linked to original sources
PubMed1992

Brain neurotransmitter changes in human narcolepsy.

We measured the concentrations of the three major monoamine neurotransmitters noradrenaline, dopamine, and serotonin, their metabolites, and receptor binding sites in autopsied brain of three patients with narcolepsy. As compared with the controls, concentrations of the noradrenaline and serotonin metabolites MHPG and 5-HIAA, respectively, were markedly elevated in cerebral cortical subdivisions of the narcolepsy patients together with a trend for above-normal neurotransmitter/metabolite "turnover" ratio. A moderately reduced number of alpha 1-adrenoceptors, as judged by the reduced levels of 3H-prazosin binding, was observed in cerebral cortex of two of the three patients with narcolepsy. Mean striatal levels of dopamine and its metabolite homovanillic acid were normal, whereas the concentration of dopamine's second metabolite, dihydroxyphenylacetic acid, was markedly reduced by 50% or greater. This was accompanied by a marked increase (+125%) in mean 3H-spiperone binding to the D2 dopamine receptor in both caudate and putamen; in contrast, the levels of 3H-SCH 23390 binding to the striatal D1 dopamine receptor were in the normal range. Our data provide evidence for altered brain monoaminergic neurotransmitter function in human narcolepsy.

Adult↗
PubMed1992

Averting CQI failure: five early warning signs.

Many hospitals, disappointed with their quality programs, are starting to ask, "What went wrong?" This article identifies five early warning signs of failing programs--and what to do about them.

Hospital Administration↗
PubMed1992

Microsurgery of the retina with a needle-guided 193-nm excimer laser.

This article presents a method used to guide the beam from an argon fluoride excimer laser to make it suitable for microsurgical purposes and confine it to areas that can be varied in dimension from 1 micron to tens or hundreds of microns. This approach guides the excimer laser beam with an articulated mechanical arm and confines it with variable-diameter tapered tubes, possibly allowing the use of this laser in in vitro retinal surgery with endolaser techniques. Currently, because of the lack of a delivery and focusing system for the 193-nm argon fluoride beam and its absorption by biologic liquids, this laser is used exclusively in ophthalmology for topical applications, such as corneal sculpting. This new method resolves these problems in a unique way with impressive results. Specifically, it was shown that, with this needle-guided excimer laser, it is possible to remove retinal tissue accurately without detectable damage to surrounding cells. Applications of this new technique in retinal surgery are discussed.

Animals↗
PubMed1991

Interleukin-5, interleukin-3, and granulocyte-macrophage colony-stimulating factor cross-compete for binding to cell surface receptors on human eosinophils.

Human interleukin (IL)-5 receptors were characterized by means of binding studies using bioactive 125I-labeled IL-5. Of purified primary myeloid cells, eosinophils and basophils but not neutrophils or monocytes expressed surface receptors for IL-5. Binding studies showed that eosinophils expressed a single class of high affinity receptors (Ka = 1.2 x 10(10) M-1) with the number of receptors being small (less than 1000 receptors/cell) and varying between individuals. Among several cell lines examined only HL-60 cells showed detectable IL-5 receptors which were small in numbers (200 receptors/cell) and also bound 125I-IL-5 with high affinity. The binding of IL-5 was rapid at 37 degrees C while requiring several hours to reach equilibrium at 4 degrees C. Specificity studies revealed that the two other human eosinophilopoietic cytokines IL-3 and granulocyte-macrophage colony-stimulating factor (GM-CSF) inhibited the binding of 125I-IL-5 to eosinophils. No competition was observed by other eosinophil activating or nonactivating cytokines. The inhibition of 125I-IL-5 binding by IL-3 and GM-CSF was partial up to a concentration of competitor of 10(-7) M with GM-CSF consistently being the stronger competitor. Converse experiments using IL-5 as a competitor revealed that this cytokine inhibited the binding of 125I-IL-3 and of 125I-GM-CSF in some but not all the individuals tested, perhaps reflecting eosinophil heterogeneity in vivo. Cross-linking experiments on HL-60 cells demonstrated two IL-5-containing complexes of Mr 150,000 and Mr 80,000 both of which were inhibited by GM-CSF. The competition between IL-5, IL-3, and GM-CSF on the surface of mature eosinophils may represent a unifying mechanism that may help explain the common biological effects of these three eosinophilopoietic cytokines on eosinophil function. This unique pattern of competition may also be beneficial to the host by preventing excessive eosinophil stimulation.

Binding, Competitive↗
PubMed1991

193 nm excimer laser ablation of bone.

The argon fluoride excimer laser is investigated as a cutting-ablating tool for bone surgery. Quantitative measurements are presented for various fluences of laser energy and number of pulses. Histological data are presented that demonstrate the minimal damage to the surrounding material from the laser interaction. Comparisons are made for non-decalcified and decalcified bone. The differences observed, as a function of decalcification in the fluences required for specified depth penetration, are noted and a possible explanation is suggested.

Animals↗
PubMed1991

Technique for cellular microsurgery using the 193-nm excimer laser.

A new cell surgery technique has been developed to produce well-defined alterations in cells and tissue without detectable heating and/or other structural damage in the surroundings. The technique involves the use of an argon fluoride excimer laser, in the deep ultraviolet (UV) region of the spectrum at 193 nm, which is guided through a glass pipette filled with a positive air pressure. To demonstrate the method, holes were drilled in the zona pellucida of mouse oocytes. The diameter of the drilled hole was determined by the pipette tip size, and its depth by an energy emitted per pulse and number of pulses. Scanning electron microscopy of the drilled mouse oocytes showed uniform, round, well-circumscribed holes with sharp edges. Oocytes that had their zona pellucida drilled with this new method fertilized in vitro and developed to the blastocyst stage in a rate similar to that of control group. These results demonstrate the nonperturbing nature of this cold laser microsurgical procedure. In addition to the extension of our results for clinical in vitro fertilization purposes, such as enhancement of fertilization and embryo biopsy, there are wide-ranging possible uses of our method in fundamental and applied investigations that require submicron accuracy in cellular alteration.

Animals↗
PubMed1991

Racial differences in affirmation of personal habit change to prevent HIV infection.

METHODS: In the context of an epidemiological investigation of AIDS-related knowledge, attitudes, and practices, 2,006 employees of the Tennessee Mental Health and Mental Retardation residential facilities were surveyed to test the hypothesis that blacks have been differentially sensitized to their disproportionate level of HIV vulnerability. RESULTS: We found that blacks were significantly more likely than whites to affirm personal habit changes to prevent HIV infection (P less than 0.00001) and significantly more likely to reject the notion that AIDS is not a threat to rural areas of the United States (P less than 0.00001). CONCLUSION: These data were interpreted to be suggestive evidence that blacks have been effectively sensitized to the disproportionate threat of AIDS to the black community and may represent an increased receptivity of blacks to the adoption of HIV preventive practices.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Multiple basal cell carcinomas and HLA frequencies in southern Australia.

An association between HLA-DR1 and the development of multiple basal cell carcinomas was detected in southern Australia. A reduction in HLA-DR4 was found in patients with basal cell carcinoma compared with a local control group. The relative risk for HLA-DR1 was 2.1, which was lower than that for persons in farther countries from the equator.

Adult↗
PubMed1991

Na+/H+ antiport and buffering capacity in human polymorphonuclear and mononuclear leucocytes.

1. Na+/H+ antiport activity was measured in peripheral blood polymorphonuclear and mononuclear cells of 12 healthy subjects by using an intracellular pH clamp technique to determine the external Na(+)-dependent H+ efflux rate in cells loaded with a pH-sensitive fluorescent dye, bis(carboxyethyl)carboxyfluorescein. The change in external Na+ concentrations for all pH measurements was similar in both cell types. 2. A significant difference between the two types of cells was found, the polymorphonuclear leucocytes having a higher Na+/H+ antiport activity than the lymphocytes. Cellular intrinsic buffering capacity measured in the absence of HCO3- was also higher in the polymorphonuclear cells than in the lymphocytes. 3. These differences may be associated with a difference in the role of the Na+/H+ exchanger in these two types of cells, although in vivo the presence of HCO3-/Cl- exchangers may also contribute to intracellular pH homoeostasis.

Adult↗
PubMed1991

Age and multiple basal cell carcinomas in Australia.

A survey of patients with skin cancer in southern Australia detected that the development of multiple BCCs is common. The incidence of multiple BCCs peaks during the sixth decade and reaches a plateau. Human leukocyte antigen (HLA) DR1 was associated with the development of multiple BCCs in people under the age of 55, but not in older people.

Adult↗
PubMed1991

Clinically unsuspected inclusion body myositis.

We describe a patient with inclusion body myositis presenting as chronic, therapy resistant polymyositis. Our report highlights the slow evolution of inclusion body myositis in some patients, and emphasizes the diagnostic importance of examining one or more muscle biopsy specimens by both frozen section and electron microscopy.

Biopsy↗
PubMed1991

The optical near-field and cell biology.

A new form of scanning light microscopy is described in which the lens is replaced by a point of light that is smaller than the wavelength. Resolution is obtained that is defined not by the wavelength but by the size of the spot of light. This is the case so long as the point of light is within the dimension of a wavelength from the surface that is to imaged or within the optical near-field. This new form of light microscopy is called near-field scanning optical microscopy (NSOM). Resolutions are being obtained with NSOM that are similar to scanning electron microscopy but without the destructive effects of a vacuum or of an electron beam. In addition such a microscope is readily interfaced with fluorescent and non-fluorescent contrast enhancing stains that are commonly used in cell biology. The possibility of a near-field/far-field microscope is discussed with overlapping resolutions from a few hundred of a conventional microscope to the tens of thousand that can be obtained with NSOM.

Engineering↗
PubMed1990

Group behavioral treatment of retentive encopresis.

Investigated the efficacy of behavioral group treatment for children with retentive encopresis who had previously failed medical management. Eighteen children between the ages of 4 and 11 years and their parents were seen in small treatment groups of 3 to 5 families over 6 sessions. The sessions focused on education about retentive encopresis, and the integration of behavioral parenting procedures with medical management. Parents and children were taught to deliver an enema clean-out, increase the children's dietary fiber, and appropriate toileting techniques. The results indicated that children significantly increased their fiber consumption by 40%, increased appropriate toileting by 116%, and decreased their soiling accidents by 83% pre- to posttreatment. Further, these treatment gains maintained or improved at the 6-month follow-up. The results are discussed in terms of cost-effective interventions and the interface between psychology and medicine in pediatric psychology.

Age Factors↗
PubMed1990

Cortical-basal ganglionic degeneration.

We report our experience with 15 patients believed to have cortical-basal ganglionic degeneration. The clinical picture is distinctive, comprising features referable to both cortical and basal ganglionic dysfunction. Characteristic manifestations include cortical sensory loss, focal reflex myoclonus, "alien limb" phenomena, apraxia, rigidity and akinesia, a postural-action tremor, limb dystonia, hyperreflexia, and postural instability. The asymmetry of symptoms and signs is often striking. Brain imaging may demonstrate greater abnormalities contralateral to the more affected side. Postmortem studies in 2 patients revealed the characteristic pathologic features of swollen, poorly staining (achromatic) neurons and degeneration of cerebral cortex and substantia nigra. Biochemical analysis of 1 brain showed a severe, diffuse loss of dopamine in the striatum. This condition is more frequent than previously believed, and the diagnosis can be predicted during life on the basis of clinical findings. However, as with other "degenerative" diseases of the nervous system, a definitive diagnosis of cortical-basal ganglionic degeneration requires confirmation by autopsy.

Aged↗