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Biomedical subjects

R Martin

Publications and source records attributed to R Martin.

At least 433 records · Page 24Linked to original sources
PubMed1992

Formant trajectory characteristics of males with amyotrophic lateral sclerosis.

The purpose of this study was to describe the formant trajectories produced by males with amyotrophic lateral sclerosis (ALS), a degenerative neuromuscular disease that is typically associated with dysarthria. Formant trajectories of 25 males with ALS and 15 neurologically normal geriatric males were compared for 12 words selected from the speech intelligibility task developed by Kent et al. [J. Speech. Hear. Disord. 54, 482-499 (1989)]. The results indicated that speakers with ALS (1) produced formant transitions having shallower slopes than transitions of normal speakers, (2) tended to produce exaggerations of formant trajectories at the onset of vocalic nuclei, and (3) had greater interspeaker variability of formant transition characteristics than normal speakers. Within the group of ALS speakers, those subjects who were less than 70% intelligible produced distinctly more aberrant trajectory characteristics than subjects who were more than 70% intelligible. ALS subjects who were less than 70% intelligible produced many trajectories that were essentially flat, or that had very shallow slopes. These results are discussed in terms of the speech production deficit in the dysarthria associated with ALS, and with respect to the potential influence of aberrant trajectories on speech intelligibility.

Adult↗
PubMed1992

Temperature and structural effects on transfer of double-stranded RNA among isolates of the chestnut blight fungus (Cryphonectria parasitica).

Cryphonectria parasitica is a unique fungus which can serve as a model for understanding transfer of genes between eukaryotic microorganisms. We studied transfer of double-stranded RNA (dsRNA) between compatible and incompatible strains of C. parasitica to determine whether hyphal types or temperature could restrict that exchange. Hyphal connections between incompatible strains occurred at about 30% of the frequency of connections between compatible strains and differed morphologically. Gel electrophoresis and in situ hybridization confirmed that dsRNA was transferred through substrate hyphae but not through aerial hyphae. Freezing temperatures resulted in the loss of dsRNA from the new mycelium of the donor colony and stimulated the production of virulent pycnidiospores. These temperature and structural restrictions may help to explain the lack of spread of the dsRNA despite its presence in the field.

Ascomycota↗
PubMed1992

Homolateral ataxia and crural paresis: a syndrome of anterior cerebral artery territory infarction.

Five patients with superficial anterior cerebral artery territory infarcts in the paracentral area are reported, who developed a hemiparesis which was predominant in the leg, and with homolateral ataxia in the arm. A similar neurological picture was not observed in 1736 patients who were admitted over an eight year period to a primary care stroke centre with their first stroke. Involvement of corticopontine fibres at their origin, together with damage to the lower limb motor strip or underlying white matter, appears to have been the cause of a clinical syndrome (homolateral ataxia and crural paresis) which has been ascribed to lacunar infarction.

Aged↗
PubMed1992

Immunological aspects of demyelinating diseases.

Primary demyelination in the central nervous system results from damage to the myelin sheath or oligodendroglia and can be produced by a variety of mechanisms, including metabolic disturbances, toxicities, infection, and autoimmunity. The major human demyelinating disease affecting the central nervous system is multiple sclerosis (MS). Although the etiology of MS is not known, existing data indicate that both genetic and environmental factors contribute to pathogenesis. Experimental allergic encephalomyelitis (EAE) is induced by immunization of genetically susceptible animals with myelin proteins. This is mediated by autoimmune T cells. Characterization of MHC restriction, fine specificity of antigen recognition, and T cell receptor (TCR) usage by encephalitogenic T cells has resulted in highly specific immunotherapies. Both HLA and TCR genes have been linked to susceptibility for MS which is widely believed to be mediated by T cells that recognize an as yet unidentified autoantigen. Because of the advances in the understanding and treatment of EAE, recent research in MS has been focused on the characterization of cellular immune responses against myelin components. The results of these studies are reviewed and the potential implications of these findings for the pathogenesis and future therapy of MS are examined.

Animals↗
PubMed1992

A study of paternal age and sex ratio in sperm chromosome complements.

There is conflicting evidence as to whether the secondary sex ratio in humans decreases with paternal age. Such an age effect could be caused by an altered frequency in the production of X-chromosome and Y-chromosome-bearing sperm as a man ages. To study this possibility we analysed 9,225 sperm karyotypes from 143 men aged 21-55 years. Human pronuclear sperm chromosome complements were obtained after fusion with golden hamster oocytes. The percentage of X- and Y-chromosome complements was not significantly related to donor age.

Adult↗
PubMed1992

Growth and academic achievement in inner-city kindergarten children. The relationship of height, weight, cognitive ability, and neurodevelopmental level.

Measures of height, weight, nonverbal cognitive ability (Ravens progressive matrix), visual-motor-perceptual ability (Beery-Buktenica test of Visual Motor Integration [VMI]), the imitation-of-gestures technique, and academic achievement (Stanford Early Achievement) were obtained for a sample of 82 children from a poor inner-city community. In contrast to prior reports from the United States and about other developed countries, anthropometric measures were related both to academic achievement and to these measures of neurodevelopment. They were not consistently related to measures of nonverbal cognitive ability. Regression analyses revealed that general cognitive ability contributed more variance (39%) to predictions of achievement than all other variables, including weight for age (13%) and VMI (6%). Children with reduced somatic growth were likely to do poorly in school, but the data do not show that undernutrition causes learning failure. Rather, they suggest that environmental problems affecting the development of thought processes and nutrient intake precede both growth and learning failure.

Achievement↗
PubMed1992

Pure sensory stroke heralding large hemispheric infarction.

A 49-year-old with long-standing hypertension and diabetes developed numbness and sensory loss over the left side of the body consistent with a diagnosis of Pure sensory stroke (PSS). However, CT showed a subcortical infarction in the middle cerebral artery (MCA) territory, which evolved a few hours later towards a large hemispheric infarction associated with severe neurologic worsening. Doppler ultrasounds showed ipsilateral carotid occlusion and contralateral severe stenosis. These findings suggest that PSS may sometimes herald large infarction in the MCA territory in association with carotid occlusion.

Carotid Artery, Internal↗
PubMed1992

Effects of growth hormone in patients receiving total parenteral nutrition following major gastrointestinal surgery.

The purpose of the present study was to determine whether the administration of a biosynthetic human growth hormone was capable of enhancing the efficacy of total parenteral nutrition. Patients (n = 38) who had undergone major gastrointestinal surgery were randomly divided into two groups. Group I (n = 20) treated only with PN, and Group II (n = 18) treated as in Group I plus human growth hormone (4 IU daily). Our study shows that the administration of human growth hormone produces a statistically significant increase in serum levels of growth hormone, somatomedin-C, transferrin, albumin and total proteins. It also causes a positive nitrogen balance from the first 24 hours onward. These findings suggest that the administration of human growth hormone produces an increase in protein synthesis, perhaps through somatomedin-C as mediator.

Adult↗
PubMed1992

[The occurrence of aluminum-containing lysosomes in the kidney of experimentally treated rats].

Aluminium was detected by electron spectroscopic imaging and electron energy loss spectra in the lysosomes of all cell types of the nephron in rats treated with aluminium chloride after 5/6 nephrectomy. The lysosomes of kidney cells of untreated rats did not demonstrate any detectable amounts of aluminium. Electron energy loss spectra showed the regular occurrence of iron (and also other elements) in the lysosomes of both groups of rats.

Aluminum↗
PubMed1991

[Nutrition in kidney diseases].

Three dietary measures are useful for chronic progressive renal failure. In a hypertensive patient, salt restriction is a prerequisite for antihypertensive therapy. Protein restriction to 0.6 g/kg of body weight per day can slow down progression of renal disease with the exception of polycystic disease of the adult type. Ketosteril can be given for prevention of essential amino acid deficiency. A normalization of serum phosphorus is essential for slowing progression of disease as well as bone metabolism. Therefore, a diet reduced in phosphates, supported by phosphate binders is prescribed.

Amino Acids, Essential↗
PubMed1991

Purification, characterization and some properties of diacetyl(acetoin) reductase from Enterobacter aerogenes.

A new method, faster, milder and more efficient than the one previously described [Bryn, K., Hetland, O. & Stormer, F. C. (1971) Eur. J. Biochem, 18, 116-119], for purification of diacetyl(acetoin) reductase from Enterobacter aerogenes is proposed. The experiments carried out with the electrophoretically pure preparations obtained by this procedure show that the enzyme (a) produces L-glycols from the corresponding L-alpha-hydroxycarbonyls by reversible reduction of their oxo groups and also reduces the oxo group of uncharged alpha-dicarbonyls converting them into L-alpha-hydroxycarbonyls, and (b) is specific for NAD. This is a new enzyme for which we suggest the systematic name of L-glycol: NAD+ oxidoreductase and the recommended name of L-glycol dehydrogenase(NAD). The molecular mass, pI, affinity for substrates and pH profiles of this enzyme are also described.

Alcohol Oxidoreductases↗
PubMed1991

Purification and characterization of the Saccharomyces cerevisiae mitochondrial leucyl-tRNA synthetase.

We have purified the product of the NAM2 gene, the mitochondrial leucyl-tRNA synthetase, from yeast mitochondria. The purified protein cross-reacts with antibodies raised against the product of a LacZ/NAM2 gene fusion and antibodies raised against the purified Escherichia coli leucyl-tRNA synthetase. The mass as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis is about 100 kDa, consistent with the size predicted by the gene sequence (102 kDa). The N-terminal sequence of the protein has been determined and shows that the first nine amino acids predicted by the gene sequence have been removed, probably during transport into the mitochondria.

Adenosine Triphosphate↗
PubMed1991

A myelin basic protein peptide is recognized by cytotoxic T cells in the context of four HLA-DR types associated with multiple sclerosis.

We have examined previously the peptide specificity of the T cell response to myelin basic protein (MBP) in patients with multiple sclerosis (MS) and healthy controls, and demonstrated that an epitope spanning amino acids 87-106 was frequently recognized. Because this region is encephalitogenic in some experimental animals, it has been postulated that the response to the epitope may have relevance to MS. In this study, the fine specificity of this response is studied using four well-characterized, monospecific T cell lines from three MS patients and an identical twin of a patient. Each of the lines recognized a peptide with the same core sequence, amino acids 89-99, although the responses were affected to various degrees by truncations at the COOH- or NH2 terminal ends of the 87-106 epitope. Importantly, the epitope was recognized in conjunction with four different HLA-DR molecules. Also, the T cell receptor beta chain usage was heterogeneous, and each line expressed a different VDJ sequence. The four HLA-DR molecules restricting the response to this epitope have been shown to be overrepresented in MS populations in various geographic areas, suggesting that the response to this region of the MBP molecule may be relevant to the pathogenesis of MS. These findings may have important implications in designing therapeutic strategies for the disease.

Amino Acid Sequence↗