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Biomedical subjects

R G Brown

Publications and source records attributed to R G Brown.

At least 91 records · Page 5Linked to original sources
PubMed1987

Mood swings associated with the 'on-off' phenomenon in Parkinson's disease.

Mood swings accompanying the motor fluctuations of patients with Parkinson's disease on chronic levodopa treatment frequently occur, but are poorly recognized. Occasionally, their functional impact may be greater than that caused by the motor disability itself. In this study we have assessed the nature of, and relationship between, mood and motor fluctuations in nine Parkinsonian patients with 'on-off' motor swings. The results of an additional questionnaire survey confirm that 'on-off' mood swings occur in approximately two thirds of patients with Parkinson's disease experiencing motor fluctuations on dopaminergic treatment. Aetiological and therapeutic implications are discussed.

Adult↗
PubMed1986

Connective tissue metabolism in muscular dystrophy. Early amino acid changes in collagen types isolated from the gastrocnemius muscle of developing dystrophic chicken embryos.

The amino acid composition of all collagen types present in the gastrocnemius muscle of dystrophic chick embryos showed an altered profile at both day 14 and day 20 in ovo when compared with the controls. The changes observed at both day 14 and day 20 in ovo suggests that there is a removal of polar side-chains in dystrophic collagen and substitution with non-polar amino acids. The amino acid composition data between day 14 and day 20 indicated: (a) a decrease in hydroxylation (hydroxyproline and hydroxylysine) with a concurrent increase in proline and lysine and a decrease in the levels of arginine; (b) the levels of glycine and alanine did not change with age; and (c) the ratios of glycine to hydroxyproline and proline to hydroxyproline changed significantly in all dystrophic collagen types between day 14 and day 20. Contrast analysis results clearly showed that the changes in amino acid composition observed in each dystrophic type of collagen between day 14 and day 20 were not due to the effect of aging but to some other factor(s). This study provides more evidence that a problem lies in the biosynthesis of collagen present in developing muscles of dystrophic chick embryos, particularly with respect to the transcription or translation of procollagen genes and/or a failure in the processing and differentiation of collagen types.

Amino Acids↗
PubMed1986

Visuospatial function in Parkinson's disease.

Previous research on visuospatial function in Parkinson's disease is reviewed. The present experiment was designed to test two fundamental aspects of spatial ability, namely right-left discrimination and the manipulation of those concepts in different spatial perspectives. Measures of accuracy and reaction time were taken. The performance of patients with Parkinson's disease did not differ from that of normal subjects in the spatial components of the task. Neither a review of the literature, nor the results of the present study, give support to the idea of a generalized visuospatial deficit in Parkinson's disease.

Female↗
PubMed1986

Depression in Parkinson's disease: a quantitative and qualitative analysis.

Depression is a common feature of Parkinson's disease, a fact of both clinical and theoretical significance. Assessment of depression in Parkinson's disease is complicated by overlapping symptomatology in the two conditions, making global assessments based on observer or self-ratings of doubtful validity. The present study aimed to provide both a quantitative and qualitative description of the nature of the depressive changes found in Parkinson's disease as compared with normal elderly subjects and arthritis patients. As with previous studies, the patients with Parkinson's disease scored significantly higher than normal controls on various self-ratings of depression and anxiety but, in this study, did not differ from those with arthritis. Qualitatively, both the Parkinson's disease and the arthritis groups had depression characterised by pessimism and hopelessness, decreased motivation and drive, and increased concern with health. In contrast, the negative affective feelings of guilt, self-blame and worthlessness were absent in both patient groups. This pattern of depression was significantly associated with severity of illness and functional disability. However, these factors account for only a modest proportion of the variability in test scores. Probable unexplored factors are individual differences in coping style and availability of support.

Aged↗
PubMed1985

Connective tissue metabolism in muscular dystrophy. Amino acid composition of native types I, III, IV and V collagen isolated from the gastrocnemius muscle of embryonic chickens with genetic muscular dystrophy.

The amino acid composition data on types I, III, IV and V collagen isolated from embryonic dystrophic skeletal muscle strongly indicate that alterations in collagen synthesis occur in intramuscular connective tissue of developing muscles in embryonic dystrophic chickens. The changes observed in the amino acid composition of dystrophic collagen were: (a) a selective removal of polar amino acids and substitution with non-polar amino acids; (b) significant decreases in basic (lysine, hydroxylysine and arginine) and hydroxylated (4-hydroxyproline and hydroxylysine) amino acids; and (c) significant increases in the amounts of glycine, proline and alanine. The amino acid substitutions suggest a genetic alteration in the collagen synthesizing process and a change in its structure. The variations in amino acid composition of collagen from dystrophic chickens could give rise to a decrease in both inter- and intramolecular cross-linking, thus decreasing the stability and functionality of newly formed collagen fibrils. The differences associated with the dystrophic collagen reported in this study are probably due to the differences in primary structure in terms of amino acid sequence rather than post-translational modifications. The structural differences noted would also lead to an alteration of the role collagen plays in regulating the differentiation of developing muscles. The changes in amino acid structure strongly suggest that the 'collagen' formed by dystrophic chickens should be considered a collagen-like protein or 'collagenoid'.

Amino Acids↗
PubMed1985

Assessment of glomerular filtration rate and effective renal plasma flow in cystic fibrosis.

A study was conducted to examine renal function in 10 healthy control subjects and eight patients with cystic fibrosis in stable condition. Sequential bolus injections of 99mTc-DTPA and 125I-OIH were administered to assess glomerular filtration rate and effective renal plasma flow, respectively. Blood was subsequently collected for 3 hours, and urine for 24 hours. Renal clearances of both radioisotope markers were virtually identical in patients and controls. Inasmuch as neither glomerular filtration rate nor effective renal plasma flow was enhanced in patients with cystic fibrosis, increased clearance of drugs in these patients is unlikely to be the result of enhanced glomerular filtration or tubular secretion.

Adolescent↗
PubMed1984

How common is dementia in Parkinson's disease?

Current estimates suggest that about one in three patients with Parkinson's disease will become demented. Critical review of the studies on which this conclusion is based indicate that this figure is inflated. Errors in separating idiopathic Parkinson's disease from other causes of the akinetic-rigid syndrome, in differentiating dementia from confusional states, depression, and even normal ageing, and in defining and assessing dementia itself may have led to overestimation of the prevalence. A more conservative estimate is that one in five patients with Parkinson's disease is demented, but this assertion needs to be put to rigorous examination.

Aged↗
PubMed1984

Connective tissue metabolism in muscular dystrophy. Levels of collagen and mucopolysaccharides in embryonic chickens with genetic muscular dystrophy.

There were marked differences between the levels of collagen (measured as hydroxyproline) and mucopolysaccharides (measured as hexosamine) found in embryonic chicks with genetic muscular dystrophy and their normal controls. The chief differences were that the dystrophic tissues (gastrocnemius muscle and tendon, pectoralis major and skin) had: (a) greater amounts of hexosamine early in embryonic development; (b) hydroxyproline levels that rose at a faster rate, yielding different slopes than their normal controls; (c) relatively greater amounts of hydroxyproline than hexosamine later in embryonic life (day 20). Connective tissue systems in muscles were preferentially affected. The connective tissue system associated with dystrophic tissues appeared to lag behind the normal rhythm pattern of embryological development. The changes in connective tissue metabolism observed in dystrophic chicks suggested that the collagen from dystrophic embryonic chicks may be of a different structure or composition than that found in the normals.

Animals↗
PubMed1984

Alterations in cognitive performance and affect-arousal state during fluctuations in motor function in Parkinson's disease.

Sixteen patients with idiopathic Parkinson's disease were selected who were all showing severe fluctuations in motor function ("on-off" phenomenon). Measures of cognitive function and of subjective affect/arousal state were taken on two occasions, once when "on" and once when "off". Twenty-five matched normal controls were also assessed on the same measures. Results revealed, on the average, a drop in cognitive function plus an adverse swing in affect/arousal state, in the patient group in the "off" condition, compared to the levels when "on". Analysis of the data suggested that the main factor associated with cognitive function when "off" was not the severity of disability but the level of affect/arousal. The fluctuations in cognitive function found tended to be mild relative to the severe changes in motor ability, and were present in only a proportion of patients.

Adult↗
PubMed1982

Collagen levels in tissues from selenium deficient ducks.

1. Nutritional myopathy was produced in ducks by feeding the birds selenium deficient diets. The myopathy increased in severity the longer the ducks were fed the selenium deficient diet. 2. There was less total collagen and lesser amounts of soluble collagen found in the tendons of ducks fed the selenium-deficient diet. Likewise, the collagen fibrils were of decreased diameter in those birds. 3. The fibroblasts present in the tendons of the deficient ducks were degenerate. It appears the selenium deficiency produced damaged fibroblast membranes which resulted in decreased collagen synthesis. The resultant loss of collagen structure could have produced a functional tendotomy which caused myodegeneration.

Animals↗
PubMed1981

Free jejunal grafts for reconstruction of pharynx and cervical esophagus.

Reconstruction of the pharynx and cervical esophagus is a surgical challenge associated with high complications, multiple-staged procedures, and prolonged hospitalizations. In a series of cases, single-stage transfer-free jejunal graft reconstructions had a 85% success rate with low complications in a series of patients who received preoperative, postoperative, and curative radiation treatment. There are advantages to this reconstruction procedure; however, there can also be complications.

Aged↗
PubMed1981

Synthesis and structure--activity relationships of selected tricyclic oxime O-ethers as potential anticholinergic agents.

Selected isomeric and nonisomeric oxime O-ether derivatives of thioxanthone oxime were synthesized and evaluated for anticholinergic activity. The oxime O-ethers were prepared via O-alkylation of the oximate anion with appropriate aminoaklyl halides. Separation and isolation of the structural isomers were accomplished through dry-column chromatography. The racemic alpha-methyl isomer was resolved via formation of tartrate diastereomers, which were subsequently isolated. All synthesized compounds exhibited significant antimuscarinic activity. A comparison of the antimuscarinic activities of these compounds revealed that the racemic alpha-methyl isomer was the most potent and that the racemic beta-methyl isomer was the least potent. Structure-activity relationships among the oxime O-ether derivatives synthesized are discussed.

Animals↗
PubMed1981

Ultrastructural studies on the gastrocnemius tendon of selenium-deficient ducklings.

This paper presents an ultrastructural study of the changes occurring in the gastrocnemius tendon of normal and selenium-deficient ducklings from 1 to 12 days of age. The study revealed that the normal 1--8-day-old duckling tendon contained 2 morphologically distinct cell types and a third occurring at Days 8--12. The location of these cells within the endotendineum and fiber bundles and their morphologic characteristics are presented. Most cells showed cytologic alterations as early as 4 days on the deficient diet with progressive deterioration to Day 12. The various cell types showed a differential response to the deficiency. Changes included altered endoplasmic reticulum and Golgi apparatus and eventual cell rupture. The significance of these observations and their possible relationship to the etiology of selenium-deficiency-induced dystrophy is discussed.

Animals↗
PubMed1980

Synthesis, stereochemical analysis, and neuromuscular blocking activity of selected E,E- and Z,Z-isomeric O-ethers of 4-androstene-3,17-dione dioximes.

A number of selected geometric oxime ethers were synthesized as potential neuromuscular blocking agents. The study consisted of the synthesis, separation, and stereochemical analysis of selected compounds followed by a preliminary pharmacological evaluation for neuromuscular blockade. Synthesis of the compounds began with the double oximination of 4-androstene-3,17-dione followed by TLC, column chromatography, and fractional crystallization as the purification methods. These procedures yielded two of the possible four isomers. Configurational assignments on the isolated pair were based on experiments using IR, UV, and NMR spectroscopy. Isomerically pure diethers were prepared by two methods: (a) O-alkylation of the stereochemically pure dioximes with the appropriate aminoalkyl halide, and (b) O-alkylation of the dioxime mixture followed by quaternization and subsequent isolation of configurationally pure salts via fractional crystallization. A preliminary pharmacological evaluation was conducted by using mice on a treadmill apparatus. Some structure--activity relationships are discussed.

Androstenedione↗