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Biomedical subjects

J A McLaughlin

Publications and source records attributed to J A McLaughlin.

At least 19 recordsLinked to original sources
PubMed2004

Macrophage responses to vascular stent coatings.

Diamond-like carbon (DLC) films have been proposed as potential coatings for blood-contacting devices. In this study, tetrahedral amorphous carbon (ta-C) films deposited by filtered cathodic vacuum arc system (FCVA) were compared with commercially deposited polyurethane coatings (PU) and uncoated stainless steel samples. X-ray reflectivity (XRR) measurements were performed to check density and thickness of the ta-C coatings, and contact angles measurements were used to assess surface wettability. J774 macrophages were used to assess the cell responses to the materials. Cell number, metabolic activity, and hydrogen peroxide production were measured by using biochemical assays, and the cell attachment and morphology were determined by using scanning electron microscopy and confocal laser scanning microscopy. Wettability measurements showed that of the materials, the stainless steel was the most hydrophilic, and the ta-C coatings were the most hydrophobic. Although the initial attachment and morphology did not appear to be dependent on the wettability, the cell numbers did increase with increasing wettability. Macrophages on the stainless steel samples were the most active in producing hydrogen peroxide. These data show that ta-C samples performed as well as commercial PU-coated samples in blocking cell reactions to the substrate and may prove to be effective coatings for blood-contacting materials.

Animals↗
PubMed2004

Experimental determination of compound action potential direction and propagation velocity from multi-electrode nerve cuffs.

Information extracted from whole-nerve electroneurograms, recorded using electrode cuffs, can provide signals to neuroprostheses. However, the amount of information that can be extracted from a single tripole is limited. This communication demonstrates how previously unavailable information about the direction of action potential propagation and velocity can be obtained using a multi-electrode cuff and that the arrangement acts as a velocity-selective filter. Results from in vitro experiments on frog nerves are presented.

Action Potentials↗
PubMed1998

Glenoid replacement in total shoulder arthroplasty.

The outcome of total shoulder arthroplasty is largely based on the quality of glenoid component fixation, which, in turn, is related to the amount and quality of bone stock, glenohumeral stability, and rotator cuff function. This article discusses the anatomic and pathologic indications for glenoid replacement, surgical techniques, and results.

Arthroplasty, Replacement↗
PubMed1993

Calcium buffer injections inhibit cytokinesis in Xenopus eggs.

A slow cortical wave of high calcium accompanies the elongation of cleavage furrows in medaka fish eggs as well as in Xenopus eggs. We explored the role of such waves by injecting calcium buffers into Xenopus eggs at various times before and during first and second cleavage. Injection earlier than about 15 minutes before first cleavage normally starts delays it for hours. Injection between about 15 minutes and a few minutes before cleavage normally starts allows a (short) furrow to form on time but usually yields an eccentric one. This forms away from the injection side, often as far off-center as the egg's equator, and then regresses. Injection soon after it starts quickly arrests elongation of the furrow and eventually induces its regression; while injection a bit later likewise soon arrests elongation but allows delocalized furrow deepening to continue. The dependence of these inhibitory actions upon the dissociation constants and final cytosolic concentrations of the injected buffers indicates that they act as shuttle buffers to suppress needed zones of high calcium in the micromolar range. We conclude that the high calcium that is found within these furrows is needed to induce them, to extend them and even to maintain them. Moreover, while short, eccentric furrows often form as far off center as the equator, they somehow always form along a meridian through the animal pole. This seems difficult to explain by the orthodox, diastral model. Rather, it suggests that the cleavage furrows in Xenopus--and perhaps in animal cells quite generally--are directly induced by a diastema or telophase disc rather than by the asters.

Animals↗
PubMed1991

Parental occupation and intracranial neoplasms of childhood: anecdotal evidence from a unique occupational cancer cluster.

Near the end of the data-collection phase of a case-control interview study of environmental factors and childhood brain tumors, an unusual space-time cluster was revealed. Not only had six genetically unrelated children been diagnosed with a primary intracranial tumor in a recent 2.4 year period in a rural county in Ohio, but each child had one parent employed by the same company (two mothers, four fathers). This represents an observed/expected ratio greater than 70 (p much less than 0.001). All tumors were microscopically confirmed, and all case parents worked at the facility in question for at least 1 year prior to conception, during the index pregnancy, and for at least 6 months after birth. The place of parental employment was an electronics firm (Standard Industrial Classification [SIC] group number 367, electronic components and accessories), where more than 100 chemical compounds are used by the company in a manufacturing process. Results of the cluster investigation are described, including a description of the case series. This cancer cluster is unique in that the index case series is composed of the offspring of workers, not the workers themselves.

Adolescent↗
PubMed1991

Family history and brain morphology in schizophrenia: an MRI study.

This study examined neuroanatomical differences between male schizophrenic patients with a family history of psychosis (n = 16) and those without such a history (n = 15). Intracranial area, cerebral area, ventricular size, and cortical atrophy were assessed using magnetic resonance imaging (MRI). Third ventricular enlargement was more prevalent in patients than controls (n = 15). Familial and nonfamilial patients differed significantly. Reduced cranial and cerebral areas without ventricular enlargement characterized familial patients, whereas nonfamilial patients showed marked lateral ventricular enlargement without a reduction in cranial/cerebral size.

Adolescent↗
PubMed1989

Effects of recombinant interleukin-1 beta on phospholipase A2 activity, phospholipase A2 mRNA levels, and eicosanoid formation in rabbit chondrocytes.

We have investigated the effects of recombinant interleukin-1 beta (rIL-1 beta) on phospholipase A2 activity (PLA2), PLA2 messenger RNA levels, and eicosanoid production in rabbit chondrocytes. Phospholipase A2 activity increased 5 fold with exposure to 1.6 x 10(-11) M rIL-1 beta for 20 hours. An mRNA specific for an extracellular PLA2 was detected by RNA blot hybridization after treatment of the cells with rIL-1 beta. Hydroxylated derivatives of arachidonic acid, including prostaglandins, leukotriene B4, 5-hydroxyeicosa 6E, 8Z, 11Z, 14Z-tetraenoic acid, 12-hydroxyeicosa 5Z, 8Z, 10E, 14Z-tetraenoic acid and 15-hydroxyeicosa 5Z, 8Z, 11Z, 13E-tetraenoic acid increased in cells after rIL-1 beta treatment.

Animals↗
PubMed1989

Perinatal complications and genetic loading in schizophrenia: preliminary findings.

History of perinatal complications (PCs) and first degree family history (FH) of psychiatric illness were examined in groups of schizophrenic/schizoaffective (n = 21) and bipolar (n = 10) patients. PCs were significantly more frequent in the schizophrenic and schizoaffective patients than in bipolar patients. An inverse relationship was found between PCs and FH status, with FH-positive patients having significantly fewer PCs than the FH-negative group. This relationship persisted when the bipolar patients were excluded. Findings emphasize the etiological importance of genetics and perinatal events in the psychoses, and support the validity of a familial/sporadic distinction.

Brain Damage, Chronic↗
PubMed1988

Enucleation versus plaque irradiation for choroidal melanoma.

The Collaborative Ocular Melanoma Study (COMS) is an international, multicenter-controlled study. The organization includes an Executive Committee, Steering Committee, 6 Central Units, 32 Clinical Centers, and a Data and Safety Monitoring Committee. Scientifically, the COMS consists of (1) a randomized trial of patients with medium choroidal melanoma treated with enucleation versus iodine-125 plaque irradiation, (2) a randomized trial of patients with large choroidal melanoma treated with enucleation versus preenucleation external beam irradiation and enucleation, and (3) a prospective observational study of patients with small choroidal melanoma to determine whether a randomized trial of treatment is appropriate. In design and conduct of the COMS, special consideration is given to biostatistics and sample size considerations, iodine-125 plaque irradiation of choroidal melanoma, and coordinated ocular melanoma research. Recruitment is in progress. However, the pool of eligible patients is limited and the COMS needs the continued support and cooperation of ophthalmologists throughout the United States and Canada.

Brachytherapy↗
PubMed1985

Enzyme-controlled scavenging of ascorbyl and 2,6-dimethoxy-semiquinone free radicals in Ehrlich ascites tumor cells.

The rate of scavenging by Ehrlich ascites cells of anionic ascorbyl and 2,6-dimethoxy-p-semiquinone free radicals has been investigated by electron spin resonance spectroscopy both for viable cells and for subcellular fractions obtained by differential centrifugation. The scavenging activity is concluded to be associated with an NAD(P)H enzyme containing an active sulfhydryl group. Attempts to identify the enzyme with the reported properties of either semi-dehydro-ascorbate reductase or DT-diaphorase have not been successful. The overall free-radical scavenging activity for viable cells is dextrose dependent and is controlled by the coulombic barrier associated with the cell-surface charge. The cytotoxicity of the mixture of ascorbic acid with 2,6-dimethoxy-p-benzoquinone is concluded to result from a loss of NAD(P)H reducing power in the cells.

Animals↗
PubMed1984

Interaction of the 2,6-dimethoxysemiquinone and ascorbyl free radicals with Ehrlich ascites cells: a probe of cell-surface charge.

The rate of quenching by Ehrlich ascites cells of anionic 2,6-dimethoxy-p-semiquinone and ascorbyl free radicals is investigated as a function of cell concentration, the blocking of cell-surface sulfhydryl groups by N-ethylmaleimide, and the reduction of cell-surface charge by neuraminidase. The rate of quenching is found to be proportional to cell viability and to the number of free cell-surface sulfhydryl groups. The enzymatic action of neuraminidase results in an increase of the free radical quenching rate, indicating that this rate can be used as a probe of cell-surface charge. Measurements as a function of the ionic strength of the suspending electrolyte gave a value of -1.22 microC X cm-2 for the charge density at the ascites cell surface. This is equivalent to a surface membrane potential of -14 mV for a 150 mM NaCl electrolyte and is a value in good agreement with published electrophoresis data.

Animals↗
PubMed1984

Co-existence of the Capgras and Ekbom syndromes.

A case is described in which a diagnosis of paranoid schizophrenia was made using the criteria of Schneiderian first-rank symptoms. The patient showed the Capgras syndrome, with delusional misidentification of her son and other people in her environment, and also Ekbom's syndrome, with the delusion that she was infested with parasitic worms which migrated between various parts of her body. In this case, the two syndromes are descriptions of a specific delusional content, and occur as part of the psychopathology within a schizophrenic disorder, rather than as distinct disease entities.

Capgras Syndrome↗
PubMed1983

Ascorbate-quinone interactions: electrochemical, free radical, and cytotoxic properties.

Standard midpoint potentials have been determined for p-benzoquinone, methoxy-p-benzoquinone and 2,3-, 2,5-, and 2,6-dimethoxy-p-benzoquinones in aqueous solution. ESR studies have been made of the ascorbate and semiquinone radicals produced when these quinones interact with sodium ascorbate. Direct correlations are found between the electrochemical potentials, generated semiquinone lifetimes, and cytotoxic action in Ehrlich ascites-bearing mice.

Animals↗