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Biomedical subjects

J M Christensen

Publications and source records attributed to J M Christensen.

At least 73 records · Page 4Linked to original sources
PubMed1989

Spouse adjustment to stroke: aphasic versus nonaphasic partners.

A survey of spouses of stroke patients examined the impact of stroke with and without aphasia on spouse role change, emotional problems, social adjustment, and the partner's perceived communication abilities. The results of this study support earlier findings that stroke with aphasia has a greater negative impact on the patient's spouse than does stroke without aphasia. For the spouses of aphasic patients sampled in this study, role changes represented the major adjustment made to a partner's stroke. These adjustments were greater than those experienced by the spouses of nonaphasic patients. The inability of aphasic patients to communicate well with their spouses served to make necessary role adjustments more difficult. Both spouse groups were affected to some degree by the communication problems associated with stroke, with the spouses of aphasic partners being affected the most.

Aphasia↗
PubMed1989

Blood lead-blood pressure relations: alcohol intake and hemoglobin as confounders.

A cohort of 1,052 persons (504 men and 548 women) born in 1936 and residing in the Glostrup area, Denmark, underwent a comprehensive physical examination in 1976 at age 40 years, and 966 underwent a complete reexamination five years later. The examinations included blood lead concentration and blood pressure assessment under careful quality control. Complete blood lead and blood pressure data were available for 861 of these subjects (451 men and 410 women). The median blood lead levels were 13 and 9 micrograms/100 ml at age 40 years and 9 and 6 micrograms/100 ml at age 45 years in men and women, respectively. A slightly increased blood lead concentration was seen at age 40 years in women with a systolic blood pressure above 140 mmHg and/or a diastolic blood pressure above 90 mmHg. Systolic blood pressure in men and women and diastolic blood pressure in women correlated significantly with log blood lead at age 40 years but not at age 45 years, a doubling in blood lead being associated with an increase in blood pressure of 3 mmHg or less. Of nine potential confounders assessed, only blood hemoglobin and alleged alcohol intake were significantly associated with both blood lead and blood pressure. If one or both confounders were entered into a multiple regression analysis, all associations between blood lead and blood pressure became nonsignificant, in some cases with a negative regression coefficient. In addition, the blood lead:hemoglobin ratio was poorly associated with blood pressure, particularly in individuals with a low alcohol intake. Because both hemoglobin level and alcohol intake appear to be biologically plausible confounders, any independent effect of low-level lead exposure on blood pressure could not be determined.

Adult↗
PubMed1988

Automatic headspace gas chromatographic method for the simultaneous determination of trichloroethylene and metabolites in blood and urine.

Trichloroethylene, trichloroethanol and trichloroacetic acid (TCA) were quantitated in blood and urine by automated headspace gas chromatography using a fused-silica capillary column coated with 3-micron silicone SE-30 and an electron-capture detector. Total trichloroethanol was determined after enzymatic hydrolysis with beta-glucuronidase and analysed together with trichloroethylene and TCA as chloroform, which are produced by decarboxylation. Analytical conditions were developed under which the thermal decomposition of TCA was optimal. The automated headspace gas chromatography is rapid and good precision is possible. Sample preparation is simple and the sensitivity of the procedure (0.02 microgram/ml) makes it suitable to estimate occupational exposure to trichloroethylene and other halocarbons in humans.

Autoanalysis↗
PubMed1988

Determination of trichloroethylene metabolites in rat liver homogenate using headspace gas chromatography.

An headspace gas chromatographic (HSGC) method for determination of trichloroethylene metabolites in rat liver homogenates is described. These metabolites are chloral hydrate (CH), trichloroethanol (TCE), trichloroacetic acid (TCA) and the glucuronic acid conjugate of trichloroethanol (TCE-beta-glucuronide). The method is based on selective thermal conversion of CH and TCA into chloroform, which is determined together with trichloroethanol by HSGC using electron-capture detection. TCE-beta-glucuronide was determined as the difference between free TCE and total TCE after enzymatic hydrolysis with beta-glucuronidase. Synthesized TCE-beta-glucuronide was used to compare the efficiency of enzymatic and acid hydrolysis of the conjugate. Enzymatic hydrolysis was found to be advantageous for determination of TCE-beta-glucuronide.

Animals↗
PubMed1988

Blood lead and erythrocyte zinc protoporphyrin in mothers and newborn infants.

Blood lead (B-Pb) and erythrocyte zinc protoporphyrin (ZPP) were measured in 78 mothers at delivery and in cord blood from 48 infants living in an area with low atmospheric Pb pollution. Median B-Pb was 35 micrograms/l (range 6-63) in mothers and 20 micrograms/l (range 6-50) in infants (P less than 0.0001), and the values were significantly correlated (rs = 0.73, P less than 0.0001). Mean B-Pb infant/B-Pb mother ratio was 0.7 (range 0.2-1.4). Mothers had lower ZPP (median 1.6 microgram/g Hb) than infants (median 2.9) (P less than 0.0001). ZPP in mothers showed a stronger relation to iron status (serum transferrin, serum ferritin) than to B-Pb (rs = 0.22, P less than 0.05). B-Pb was correlated to serum iron both in mothers (rs = 0.28, P less than 0.02) and infants (rs = 0.33, P less than 0.03). The present B-Pb levels are lower than previously reported in Scandinavia, probably due to the general decline in atmospheric Pb pollution.

Adolescent↗
PubMed1988

Health effects due to occupational exposure to cobalt blue dye among plate painters in a porcelain factory in Denmark.

Forty-six plate painters, heavily exposed to cobalt blue dye, took part in this cross-sectional study, and 51 top-glaze painters served as the referents. The study comprised a questionnaire, a health examination, a lung function test, and the determination of the blood and urinary cobalt levels. The plate painters were examined twice, at the end of a workfree period and after resuming work. More plate painters complained of irritation from the mucous membranes in the mouth and throat, cough, and expectoration than the referents. The symptoms increased after the plate painters resumed work. The cobalt level of the plate-painting group after six weeks off work was twice as high in the blood and five times higher in the urine than the corresponding values of the reference group. After the plate painters resumed work, the blood and urinary levels increased approximately 4 and 15 times, respectively. Increased airflow resistance was found in the plate group when compared with the referents, and signs of small airway obstruction increased after the plate painters resumed work. The pulse rate was higher among the plate painters, and minor changes in the red blood cell picture were observed. None of these adverse health effects were associated with the cobalt levels in the blood or urine.

Air Pollutants, Occupational↗
PubMed1988

Concentration of nickel and chromium in serum: influence of blood sampling technique.

In the determination of nickel and chromium in serum, contamination is the most important source of error. In this study the influence of needle type and collection device was investigated. For each of 20 subjects the concentrations of nickel and chromium in serum obtained by the following techniques of blood collection were compared: closed collection system (acidwashed polyethylene syringes) + (A) steel needle (Terumo), (B) teflon i.v. cannula (Abbocath-T), and (C1) teflon i.v. cannula (Venflon); (C2) open collection system (acidwashed polyethylene tubes) + teflon i.v. cannula (Venflon). For each technique the first 5 ml of blood were discarded. No statistically significant differences were found between serum concentrations of nickel and chromium in specimens collected with the sampling techniques A, B, C1 and C2. This study has shown that identical results for concentrations of nickel and chromium in serum are obtained independent of whether a steel needle or a teflon i.v. cannula is used for blood sampling, provided the first 5 ml of blood are discarded. Likewise, identical results are obtained independent of whether specimens are collected in a closed or an open collection system, provided collection devices are acidwashed and sampling takes place under hospital conditions.

Adult↗
PubMed1987

Effects of antacids and dialysate dwell times on multiple-dose pharmacokinetics of oral ciprofloxacin in patients on continuous ambulatory peritoneal dialysis.

Six stable patients on continuous ambulatory peritoneal dialysis were evaluated for the appearance of ciprofloxacin in their peritoneal dialysate following oral ingestion of 750 mg of the drug every 12 h for four doses. Three subjects participated in this study twice, once while taking and once while abstaining from phosphate-binding aluminum antacids. Subjects tolerated the medication without evidence of toxicity. Food may have delayed or decreased the absorption of ciprofloxacin, whereas antacids definitely decreased the absorption of the drug. Peak concentrations in serum noted in the absence of antacids ranged from 2.9 to 6.4 micrograms/ml, and peak concentrations in dialysate in the absence of antacids ranged from 1.8 to 4.5 micrograms/ml. Peak ciprofloxacin concentrations in serum achieved in subjects taking antacids were 14 to 50% of those achieved in subjects without antacids. The peak concentrations in dialysate achieved in subjects on antacids were 8 to 33% of those observed in subjects off antacids. The clearance of ciprofloxacin by continuous ambulatory peritoneal dialysis represented 2% of the total body (systemic) clearance. Simultaneous ratios of concentration in dialysate to concentration in serum (D/S) were determined at various durations of dialysate dwelling within the peritoneum. A progressive rise of the D/S ratio was noted as dwell time increased. At 4 h D/S was 0.57 +/- 0.07 (mean +/- standard error of the mean; n = 9), and at 8 h it was 0.75 +/- 0.04 (n = 26). Long-dwell exchanges may be necessary to achieve reasonable concentrations of orally ingested ciprofloxacin in dialysate.

Administration, Oral↗
PubMed1987

Serum ferritin and iron status in mothers and newborn infants.

Iron status, including hemoglobin, S-ferritin, S-iron, S-transferrin, transferrin saturation and the erythrocyte zinc protoporphyrin/hemoglobin (ZPP:Hb) ratio, was evaluated in 85 healthy iron-supplemented mothers at parturition and in 74 of their term newborn infants. Of the mothers, 17% had a S-ferritin level less than 15 micrograms/l (i.e. depleted iron stores), 9.9% had S-ferritin less than 15 micrograms/l and transferrin saturation less than 15% (i.e. latent iron deficiency), and 2.4% had S-ferritin less than 15 micrograms/l, transferrin saturation less than 15% and Hb less than 120 g/l (i.e. iron deficiency anemia). Newborn infants had higher S-ferritin than mothers: median 128 micrograms/l versus 21 micrograms/l (p less than 0.0001), higher transferrin saturation: 48% vs. 21% (p less than 0.0001), and higher ZPP:Hb ratio: 74 mumol/mol Hb vs. 41 mumol/mol Hb (p less than 0.0001). During the first 5 post-natal days, median S-ferritin rose from 128 to 236 micrograms/l (p less than 0.0001). S-ferritin appeared to be the best single indicator of maternal iron status. Ferritin levels in newborn infants were correlated to levels in mothers (rs = 0.36, p less than 0.01), indicating that fetal iron reserves are dependent on maternal iron stores.

Adolescent↗
PubMed1986

Occupational exposure to chlorinated organic solvents and its effect on the renal excretion of N-acetyl-beta-D-glucosaminidase.

Organic chlorinated hydrocarbon solvents are known to be nephrotoxic. However, very little is known about renal integrity after occupational exposure to these solvents. Increased urinary N-acetyl-beta-D-glucosaminidase (NAG) excretion caused by necrosis of renal tubular cells can be used as a marker for nephropathy. In this study trichloroethylene (TRI), trichloroethane and freon 113 exposed persons from metal industries have been clinically investigated, and urine samples analysed for NAG activity and for trichloroacetic acid concentration. In order to analyse for possible subclinical kidney damage a group of diabetic patients with subclinical nephropathy served as positive controls. A significant higher NAG activity (p less than 0.001) was found in the group of exposed workers as compared to the control group. About 10% of the exposed workers had an enhanced NAG value, corresponding to the level of diabetic patients with subclinical nephropathy. Increased NAG activity was observed in previously TRI-exposed persons, which might indicate induction of an autoimmune renal necrosis.

Acetylglucosaminidase↗
PubMed1986

A review of the psychological aspects of space flight.

Instances of overt, serious functional impairment of space crews caused by adverse psychologic responses have not been scientifically documented. However, transient disorientation, spatial illusions, and visual disturbances as well as anomalous myopias, sleep disturbances, and instances of substandard performance have been described. Moreover, anecdotal information describes significant psychologic aberrations in space flight. Adequate scientific data are lacking for optimal psychological and psychophysiological methods for crew selection, training, and performance evaluation, for identifying key psychosocial factors for crew compatibility, cohesiveness, and productivity, and for determining the effects of space flight on perceptual, intellectual, and motor skills. The ad hoc Working Group, convened to review psychological aspects of space flight, favored establishment of a comprehensive research and development program to address the deficiencies identified in the study.

Behavior↗
PubMed1986

Stability of levodopa in 5% dextrose injection at pH 5 or 6.

The stability of solutions of levodopa 1 mg/mL in 5% dextrose injection adjusted to pH 5 or 6 and stored at one of three temperatures was determined. Solutions were adjusted to pH 5 or 6 with sodium acetate injection or sodium phosphate injection, respectively. Three samples of solution adjusted to pH 5 were stored at each of three temperatures (4, 25, and 45 degrees C), and three samples of solution adjusted to pH 6 were stored at 25 degrees C. Samples were assayed for levodopa concentration by high-performance liquid chromatography at various times during the 21-day study period. All solutions maintained at least 90% of the initial concentration of levodopa for seven days. Discoloration of all solutions except those stored at 4 degrees C was noted at some point during the study period; solutions stored at 45 degrees C began to darken within 12 hours. The pH values of the solutions did not change during the study period. Under the conditions studied, solutions of levodopa 1 mg/mL in 5% dextrose injection adjusted to pH 5 or 6 are stable for seven days. Slight degradation of levodopa may cause a brownish-black discoloration of the admixtures.

Drug Stability↗
PubMed1986

Pharmacokinetic disposition of dimethyl sulfoxide administered intravenously to horses.

Dimethyl sulfoxide (DMSO) was administered IV to 6 Thoroughbred horses at 2 dosages: 1.0 g/kg and 0.1 g/kg. The pharmacokinetics seemed linear, with biological half-lives of 8.6 +/- 0.3 hours and 9.8 +/- 2.2 hours for the 1.0 g/kg and 0.1 g/kg dosages, respectively. This was further substantiated by mean residence times of 9.8 +/- 0.44 hours and 13.8 +/- 4.25 hours, areas under the curve of 12.55 +/- 1.42 mg/ml/hr and 1.63 +/- 0.49 mg/ml/hr, and the clearances of 0.081 +/- 0.009 L/kg/hr and 0.066 +/- 0.022 L/kg/hr for the large and small dosages, respectively. At 12 hours after 1.0 g/kg was administered, 26.6% of the DMSO dose was excreted unchanged into the urine; at 12 hours after 0.1 g/kg was administered, 25.3% of the DMSO dose was excreted unchanged into the urine. It was predicted that 29.4% and 40.6% of the total DMSO dose would be excreted into the urine for the 1.0 g/kg and 0.1 g/kg dosages, respectively. A 10% DMSO concentration in normal saline solution was safe to give as rapid IV infusion. Slow administration is recommended for more concentrated solutions. Based on the half-life, DMSO should be administered 2 times a day IV for the treatment of increased intracranial pressure and/or cerebral edema in horses.

Animals↗