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Biomedical subjects

L Campbell

Publications and source records attributed to L Campbell.

At least 163 records · Page 9Linked to original sources
PubMed1987

Behavioral changes during exposure to 1,1,1-trichloroethane: time-course and relationship to blood solvent levels.

We report the results of an exposure chamber study in which volunteers were exposed to 0, 950 mg.m-3 (175 ppm) and 1,990 mg.m-3 (350 ppm) of 1,1,1-trichloroethane for 3.5 hours. The time-course of the behavioral changes and the relationship to blood concentrations of 1,1,1-trichloroethane were investigated. A pattern of performance deficits consistent with earlier work was found for some of the tests of psychomotor performance. The time-course of these appeared to be rapid, occurring in some cases within 20 minutes of exposure. For those tasks shown to be sensitive to 1,1,1-trichloroethane exposure, the development of performance changes followed the time-course of blood solvent levels. Two behavioral tests not previously used in this type of work were also employed. One was concerned with the distractability of attention and concentration (the Stroop test), and the other was concerned with analysing grammatical statements (the syntactic reasoning test). Different effects were found. In the Stroop test, enhanced performance was observed following exposure; however, the syntactic reasoning test was found to be resistant to solvent effects. Measures of short-term subjective well-being were not affected by exposure. It is suggested that the observations of time-course effects in performance and their relationship to change in blood solvent levels have implications for psychological test selection and for study designs for examining field exposure.

Analysis of Variance↗
PubMed1987

A quantitative ultrastructural study of collagen fibril formation in the healing extensor digitorum longus tendon of the rat.

A study was made of collagen fibril populations in healing tendon using a window lesion in rat extensor tendon. Two environments were thus created. One (the lesion area) where stress levels were reduced; the other (the non-lesion area) where stress levels were increased. In both areas a population of small diameter (less than 50nm) collagen fibrils were synthesized. Lesion area fibrils increased their diameter only slowly. Non-lesion area fibrils added to a population which increased its diameter distribution comparatively rapidly. It is suggested that in the lesion area fibrils were synthesized in response to tissue damage and low levels of stress. These may be of type III collagen. In the non-lesion area fibrils were synthesized in response to raised levels of stress. These may be of type I collagen. Implications of these events, especially as they might relate to gap formation in flexor tendon surgery are discussed.

Animals↗
PubMed1987

Hopelessness.

Explore the source record for details and available documents.

Adult↗
PubMed1986

Circulating immune complexes in malignant melanoma: serial studies in 130 patients.

We evaluated the ability of repeated measurements of circulating immune complexes (CIC) to predict for tumor recurrence in 130 patients with malignant melanoma. Twenty-two patients had level 2, 45 had level 3, and 51 had level 4/5, stage I disease in remission at the start of monitoring, while 12 had stage II disease. The polyethylene glycol precipitation assay was used for serial studies, based on an initial comparative evaluation with the Clq-binding and Raji assays. The study averaged 22 +/- 11 months (6-43 months) and an average of 22 +/- 5.3 assays were performed per patient (range 3-36), with a follow-up of 4 years. CIC were present in sera in recurrent, irregular 'bursts' of activity. Serial measurements doubled the incidence of CIC compared to single determinations. Only 23% of these bursts of activity were clearly related temporarily to documented recurrences, while 34% occurred with treatment events such as surgery or immunotherapy, and 42% occurred without correlation to either recurrence or treatment. CIC activity was greater and more closely related to recurrence in high-risk stage I (level 4,5) and stage II patients. Whether analyzed as positive sera or as bursts of elevated CIC activity, CIC assays predicted for recurrence at the 5% significance level. The assay was highly sensitive (97%), but with poor specificity (21%) with many false positives (79%). The assay was helpful at ruling out recurrences (95%), but poor at ruling them in (29%). The advantage was seen only in high-risk stage I and II patients, and there was no advantage to serial assays over random single determinations. Although generally, CIC in the sera of melanoma patients were found to predict for recurrence, the use of serial CIC measures monitoring of individual patients cannot be recommended.

Antigen-Antibody Complex↗
PubMed1985

Evaluation of occupational exposure to carbon disulphide by blood, exhaled air, and urine analysis.

This paper compares three analytical methods that may be considered for monitoring workers who are exposed to carbon disulphide (CS2). An estimate of the uptake of CS2 was assessed by the measurement of "bound" CS2 in blood, CS2 in expired alveolar air, and 2-thiothiazolidine-4-carboxylic acid (TTCA) in urine. The concentration of TTCA in end-of-shift urine samples was related to exposure and appears to be a good measure of uptake of CS2.

Adult↗
PubMed1985

Melatonin and N-acetylserotonin stress responses: effects of type of stimulation and housing conditions.

The effects of housing condition and type of stimulation on serum melatonin and N-acetylserotonin (NAS) were investigated. Male rats were housed under a 12/12-hour light-dark cycle, with ad libitum food and water, either individually or in groups of four. At the start of the light phase, separate groups were sacrificed at rest or subjected for 3 minutes to the stimulation of cold water, noise, novel environment, or ether vapour and then decapitated at 0, 5, 15, 30 or 60 minutes after the end of stimulation. Melatonin was measured by a modified radioimmunoassay and NAS by a specific radioimmunoassay. Melatonin levels responded to stimulation with an increase, while NAS levels responded with a decrease. Housing condition had no effect on hormone response. However, the pattern of response for each of the two hormones differed greatly among the stimuli. For melatonin, cold water was the most potent stimulus, followed by noise, novel environment, and ether. NAS responded most to ether, fleetingly to cold, and in a bimodal manner to noise. The data are interpreted as suggesting that separate mechanisms regulate serum melatonin and serum NAS is response to environmental stimulation and that under appropriate control conditions melatonin from the pineal is very responsive to environmental stimuli, in a manner similar to that of pituitary hormones.

Animals↗
PubMed1984

Failure of myocardial ischemia to increase pulmonary microvascular permeability in dogs.

Increased extravascular lung water has been reported following periods of myocardial ischemia. To determine whether increased pulmonary microvascular permeability was produced by ischemia, total protein lymph-to-plasma concentration ratios (CL/CP) were obtained at mechanically increased left atrial pressures (Pla) before and after ligation of the left anterior descending coronary artery in dogs. Pulmonary and systemic vascular pressures and cardiac output were monitored and lymph flow was measured from an afferent tracheobronchial lymphatic. Osmotic reflection coefficients (sigma) for total protein were estimated using CL/CP = 1-sigma at high filtration rates, and permeability-surface area (PSf) products were fit to the data. The postischemic lung lymph data best fit average values of sigma = 0.68 and PSf = 0.073 ml X min-1 X 100 g-1 wet weight. There were no significant differences in lymph protein or water clearances between the pre- and postischemic increased Pla states or for myocardial ischemia compared with control values for the experimental preparation. Levels of 6-ketoprostaglandin F1 alpha, a degradation product of prostacyclin, increased by 10- to 14-fold above preischemic values in pulmonary lymph, and there was a significant increase in pulmonary vascular resistance during ischemia. Extravascular lung water was not increased above that attributed to the increased Pla alone. These data indicate no significant increase in pulmonary microvascular permeability to plasma proteins during myocardial ischemia.

6-Ketoprostaglandin F1 alpha↗
PubMed1983

Identification and enumeration of marine chroococcoid cyanobacteria by immunofluorescence.

We used an indirect immunofluorescence technique to permit the identification and enumeration of individual or closely related strains of chroococcoid cyanobacteria of the general Synechococcus and Synechocystis in natural seawater samples. Antisera directed against each of five strains (two phycoerythrin-containing Synechococcus strains, two phycocyanin-containing Synechococcus strains, and one Synechocystis strain) were produced and tested for cross-reactions with cultures of a variety of cyanobacteria and representatives of other algae and bacteria. Each antiserum was relatively specific. The observed cross-reactions occurred between strains that were isolated from similar oceanic environments. We were able, therefore, to apply this technique to field samples. Preliminary results for April to December 1982 in Great South Bay, New York, show that Synechocystis populations are present only during spring and summer, phycocyanin-containing Synechococcus strains are only a minor component in the spring and summer, and phycoerythrin-containing Synechococcus populations become significant in summer and remain so until late fall or winter.

Journal Article↗
PubMed1982

Defective expression of DR antigens in chronic lymphocytic leukemia.

HLA-DR (or Ia-like) antigens which were detergent-solubilized from plasma membranes of leukemic cells of patients with chronic lymphocytic leukemia of the B cell variety were purified by gel filtration, followed by affinity chromatography on Con A-Sepharose. After radioiodination, the DR antigens were immunoprecipitated with specific antisera and analyzed by two-dimensional gel electrophoresis. Repeated mapping revealed several different patterns of DR antigen expression. Most patients (18 out of 42) gave map patterns resembling those obtained from normal peripheral blood B cells. Such maps revealed light (27 kDa) and heavy (33 kDa) DR chains as well as a non-dissociated 60 kDa DR complex. All components, and especially DR light chains, were polymorphic and could be resolved further into several characteristic isoelectric variants. Maps from eleven patients showed decreased levels of 33 and 60 kDa antigen components, while eleven further patients expressed only DR light chains. Two patients lacked detectable DR antigens. Sequential mapping of individual patients indicated that expression of 33 and 60 kDa DR components fluctuates over months. This temporal fluctuation was independent of other B cell markers, including a newly defined group of surface membrane proteins of 28 000 daltons. The patterns are reminiscent of the biochemical dedifferentiation characteristic of immunoglobulin biosynthesis seen in the plasma cell dyscrasias.

Epitopes↗