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Biomedical subjects

J Harrison

Publications and source records attributed to J Harrison.

At least 37 records · Page 2Linked to original sources
PubMed1990

Clay occlusion of respirable quartz particles detected by low voltage scanning electron microscopy-X-ray analysis.

Respirable-sized dust particles from a clay mine and mill were examined for aluminium and silicon content by scanning electron microscopy-energy dispersive X-ray analysis at incident electron energies of 5-20 keV. Most of the high silica content particles, those which had a silicon to silicon plus aluminium signal fraction, measured at 20 keV, of 0.9 or greater, showed a decrease in the silicon fraction of signal with decreasing incident electron energy, down to values of between 0.6 and 0.8 at 5 keV: this decrease was a function of particle size and composition. Simple models for silicon fraction of signal vs incident electron voltage suggest this behaviour is due to a heterogeneous particle structure in which an aluminosilicate coating occludes the surface of a silica particle core. The coating survives incubation in a major component of pulmonary surfactant.

Aluminum Silicates↗
PubMed1990

Developing soil gas and 222Rn entry potentials for substructure surfaces and assessing 222Rn control diagnostic techniques.

Research-based procedures for characterizing the causes of elevated indoor 222Rn levels and guiding the selection of an appropriate control technique were evaluated at seven New Jersey houses. Procedures such as thorough visual inspections, blower door air leakage tests, pressure field mapping, subsurface vacuum extension tests, sampling of 222Rn concentrations throughout the substructure, and measurements of the additional depressurization caused by various appliances all were found to furnish important information to the mitigation contractor or researcher. An analysis of data from these and other diagnostic techniques performed at the seven houses also indicated: (1) regions of very high permeability existed directly adjacent to the exterior of substructure walls and floors; (2) the additional substructure depressurization caused by operation of forced-air furnaces and attic exhaust fans could exceed 1 Pascal; (3) 222Rn concentrations below basement slabs and slabs-on-grade adjoining below grade basement walls were approximately seven times higher than those within block wall cavities; and (4) air leakage areas of crawlspace and basement ceilings were quite large, ranging up to 0.15 m2. The pressure field mapping tests identified the areas surrounding the substructure that were well coupled to the indoors. Using flow, pressure difference, and 222Rn concentration data, indices of soil gas entry potential and 222Rn entry potential were developed to indicate the areas of the substructure that may have high entry rates of soil gas and 222Rn, respectively. These indices could be helpful for quantifying the relative resistance to soil gas movement of substructure surfaces and surrounding soils and for determining the placement of 222Rn control systems.

Air Pollutants↗
PubMed1990

Six-month overnight intraperitoneal amino-acid infusion in continuous ambulatory peritoneal dialysis (CAPD) patients--no effect on nutritional status.

The long-term effect of an AA solution based on Travasol, a solution for total parenteral nutrition, given intraperitoneally over a 6-month period was studied in 5 patients 22 to 75 years old, having been on continuous ambulatory peritoneal dialysis (CAPD) for 3 to 57 months. A low oral protein intake (less than 0.8 g/kg bw/day) and/or a low serum albumin (less than 35 g/L) were used as inclusion criteria. Two liters of 1% AA solution were infused overnight, while a glucose Dianeal was used for the other exchanges. During the study, BUN increased from 22.04 mM/L to 28.06 mM/L the first month and remained at these levels, indicating the increased protein intake. However, average oral total energy and protein intake, body weight (bw), serum creatinine, cholesterol, triglycerides, total proteins, albumin, transferrin, skinfold thickness, total body potassium, and plasma AA levels remained basically unchanged. The average total body nitrogen decreased from 1.746 to 1.554 Kg, but this decrease did not reach statistical significance (p greater than 0.05). We conclude that intraperitoneal overnight administration of 2 L of 1% AA based on Travasol over 6 months did not improve the nutritional status of CAPD patients. This ineffectiveness might be due to the AA composition of the solution, the timing of administration, or to a low caloric intake and/or that our patients were not severely malnourished.

Amino Acids↗
PubMed1990

Evaluation of blood flow in human rectal tumours using a laser Doppler flowmeter.

A TSI laser Doppler flowmeter was used via a rigid sigmoidoscope in 20 consecutive patients with rectal carcinoma. Blood flow and velocity was evaluated at the tumour centre, tumour edge and adjacent normal mucosa; blood flow in the centre of the tumour was significantly higher than in normal mucosa (P = 0.05) and the tumour edge (P = 0.037). Two patients with ulcerated lesions had much lower blood flow in the centre of the ulcerative lesion.

Blood Flow Velocity↗
PubMed1990

The headless human.

Explore the source record for details and available documents.

Health Education↗
PubMed1989

von Willebrand factor multimer analysis using a sensitive peroxidase staining method.

A peroxidase staining method for von Willebrand factor (vWF) multimer analysis was modified for comparison with an autoradiographic method. This method consists of SDS-agarose electrophoresis followed by blotting to a nitrocellulose membrane and a sensitive peroxidase staining method. The resolution of vWF multimers on the nitrocellulose membrane is comparable to that on the conventional autoradiography. Results can be obtained in 3 days. This nonradioisotopic method will be useful for the determination of the type of von Willebrand's disease in clinical laboratories.

Autoradiography↗
PubMed1989

A request for the 'morning-after' pill.

A request for post-coital contraception may be the first consultation by a young girl for contraceptive advice. The problem may be used as an opportunity to discuss other relevant issues such as AIDS. The case will need sympathetic and sensitive handling and demands consideration of confidentiality, especially in Samantha's case as she is only 15.

Adolescent↗
PubMed1989

Prevention and rehabilitation of osteoporosis program: exercise and osteoporosis.

Osteoporosis is a common crippling bone disease affecting post-menopausal and elderly women. It results in fractures, spinal deformity and chronic pain leading to decreased mobility and functional disability. A preventive program in Toronto, described in this article, aims to prevent bone loss and maximise the functional capacity of osteoporotic patients through a program with educational, social and exercise components. Evaluation of the program, also reported here, showed that 80 per cent of patients complied with the requirements of the exercise program and that those who exercised reported improvement in general well being, stamina, mobility and pain tolerance. The exercise group also showed a significant improvement in VO 2 max (p less than 0.001) and bone mass (p less than 0.02) after one year of exercise. None of the patients developed fracture as a direct result of the exercise. The exercise prescribed for osteoporosis is safe and beneficial. The program is a social success.

Aged↗
PubMed1989

Randomised double blind controlled trial of cyclosporin in multiple sclerosis.

In a 2 year double blind controlled trial of cyclosporin against placebo in multiple sclerosis conducted at two centres there was a beneficial effect of the therapy upon the progression of the disease, relapse rate and relapse severity at one of the centres where the patients received a mean dose of 7.2 mg/kg/day. This beneficial effect was not seen in the other centre where a lower dose (mean 5 mg/kg/day) was given. Reduction in clinical progression was accompanied by decreased IgG synthesis in the central nervous system. Side effects included hypertension, renal insufficiency and anaemia and were of such severity to preclude the use of cyclosporin in a high enough dose to alter the course of the disease.

Adolescent↗
PubMed1989

Posterior cortical atrophy.

Two patients had a steadily progressive disorder of higher cortical function dominated by the early development of cortical visual deficits. In one, a right visual inattention progressed over a period of 2 years to a complete right homonymous hemianopia and relative left inferior quadrantanopia. In the second case, blind in the left eye for unrelated reasons, a temporal field loss was noted at presentation in the right eye, with the subsequent development of field loss in the inferior nasal quadrant on that side. Features of Balint's syndrome developed in both patients, with sticky fixation, ocular dysmetria and simultanagnosia. Prominent associated features were progressive dysmnesia, dyscalculia, ideomotor apraxia and spatial disorientation. Abstract reasoning, speech function and insight were all well preserved. MRI and CT scans revealed no focal abnormalities. These cases are similar to the 5 recently described by Benson et al. The pathological basis is unknown but may be an atypical form of Alzheimer's disease.

Atrophy↗
PubMed1988

Analysis of the amino acid and sugar composition of streptococcal cell walls by gas chromatography-mass spectrometry.

A procedure for determining the amino acid and sugar composition of streptococcal peptidoglycan-polysaccharide complexes by capillary gas chromatography-mass spectrometry (GC-MS) was established. Amino acids are analysed as butyl heptafluorobutyl derivatives and sugars as alditol acetates. These two different groups of compounds are derivatized independently but chromatography in both cases utilizes the same OV-1701 fused-silica capillary column which simplifies GC-MS analysis. The butyl heptafluorobutyl procedure incorporates new pre- and post-derivatization clean-up steps. Additionally, selected-ion monitoring MS allows amino acids to be readily analysed without interference from background noise.

Amino Acids↗
PubMed1988

Adrenocorticotrophin (ACTH) deficiency undetected by standard dynamic tests of the hypothalamic-pituitary-adrenal axis.

Six patients (four females, two males; aged 18-65 years), previously treated by external pituitary irradiation (2000-4000 cGY in 8-15 fractions over 10-20 days) for pituitary tumours, presented with the symptoms of excessive and inappropriate tiredness suggestive of ACTH deficiency, despite a normal peak cortisol response to an insulin tolerance test (four cases) or to a glucagon stimulation test (two cases). These six patients were found to have significantly lower mean 24 h urinary free cortisol levels (100 +/- 40 nmol; mean +/- SD) compared with the mean value of 31 normal controls (210 +/- 70.8 nmol; P less than 0.01). In addition serum cortisol profiles based on a series of four timed samples between 0900-2300 h were subnormal (mean 130 nmol/l) in comparison with profiles obtained from 12 normal controls (mean 270 nmol/l) (P less than 0.001). Glucocorticoid replacement therapy promptly abolished their symptoms. These results suggest that a discordance between ACTH secretion under basal circumstances and ACTH response to pharmacological tests may exist in patients with ACTH deficiency. We speculate that defective endogenous corticotrophin-releasing hormone (CRF) secretion, due to radiation-induced damage at hypothalamic level, is one cause of this phenomenon.

Adolescent↗
PubMed1987

Type IIA von Willebrand disease with apparent recessive inheritance.

Type IIA von Willebrand's Disease (vWD) is the most common type II variant, and all reported cases (56 individuals in 26 families) have had autosomal dominant inheritance. An eight-year-old female with an increased bleeding tendency since infancy was found to have laboratory values typical of type IIA vWD, but her parents and siblings were asymptomatic. With the exception of uniformly decreased levels of ristocetin cofactor in relation to von Willebrand factor antigen, the results of family studies were normal including the presence of large multimeric forms of von Willebrand factor antigen. These findings are consistent with the propositus having the homozygous state of an autosomal recessive trait. Desmopressin infusion in the propositus was followed by a significant increase of factor VIII coagulant and von Willebrand factor antigen but a limited change in ristocetin cofactor with no development of large multimers.

Antigens↗