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Biomedical subjects

S Hansen

Publications and source records attributed to S Hansen.

At least 361 records · Page 20Linked to original sources
PubMed1977

Axonal dysfunction in the neuropathy of diabetes mellitus: a quantitative electrophysiological study.

The extent of axonal dysfunction in a group of patients with diabetes mellitus has been investigated using recently introduced quantitative techniques of electromyography. In 40 diabetic patients, estimates of motor unit numbers in the extensor digitorum brevis muscles and measurements of the parameters of electrically evoked motor unit potentials therein are presented, along with significant correlations between these parameters and motor nerve conduction velocities and distal motor latencies in the lateral popliteal nerves. The results indicate that axonal dysfunction and concomitant collateral reinnervation are prominent and integral features of the neuropathy of diabetes mellitus. Axonal dysfunction is present in proportion to and parallels the severity of the demyelinative lesion. It is also extensive in patients without clinical evidence of neuropathy in whom the accompanying collateral reinnervation is of sufficient magnitude to mask the clinical signs of motor involvement.

Adult↗
PubMed1977

Studies of the glycine cleavage enzyme system in brain from infants with glycine encephalopathy.

Glycine content and enzyme activity of the glycine cleavage system were compared in autopsied brain from five infants dying with glycine encephalopathy and four control infants, including two with other types of hyperglycinemia. Glycine content was elevated 2- to 8-fold and glycine cleavage enzyme activity was undetectable in the brains of the glycine encephalopathy patients. Glycine content and enzyme activity were normal in the brains of the control patients, including one with ketotic hyperglycinemia secondary to methylmalonic acidemia. Prolonged dialysis failed to restore glycine cleavage enzyme activity in brain homogenates of glycine encephalopathy patients, and these homogenates failed to inhibit enzyme activity when added to homogenates of control brain. Radioactive bicarbonate was converted to radioactive glycine by control brain, but not by glycine encephalopathy brain. This finding, together with the results of recombination experiments between solubilized human brain enzymes and purified protein components of the bacterial glycine cleavage system of Arthrobacter globiformis, indicates that the enzyme defect in glycine encephalopathy involves at least the second or H protein of the 4-protein glycine cleavage enzyme system.

Amino Acid Metabolism, Inborn Errors↗
PubMed1977

Aspartate-taurine imbalance in dominantly inherited olivopontocerebellar atrophy.

Amino acids were measured in autopsied brain from two patients who died with a dominantly inherited form of olivopontocerebellar atrophy. Neuropathologic changes found in the brain of these patients suggested a loss of cerebellar climbing fibers. The contents of aspartic acid, gamma-aminobutyric acid, and homocarnosine were reduced in the cerebellar cortex and the dentate nucleus, while taurine content was markedly elevated in the same brain regions. These findings are compatible with the possibility that aspartic acid is the excitatory synaptic transmitter of the climbing fibers and taurine is the inhibitory neurotransmitter of one or more types of interneurons in the cerebellum.

Adult↗
PubMed1977

Effects of oestradiol and progesterone on the induction and duration of sexual receptivity in cyclic female rats.

Intact 4-day cyclic rats showed sexual receptivity 24 h after an injection of oestradiol benzoate (OB) on any day of the cycle except on the second day after the display of spontaneous oestrus. Ovariectomy at the time of OB treatment abolished the behavioural response, but receptivity was restored by progesterone. Progesterone treatment early on the day of behavioural oestrus advanced the display of receptivity but did not affect the time at which oestrus ended. Repeated treatment of sexually receptive rats with progesterone did not affect the duration of oestrus. These results show that sexual receptivity in the intact rat cannot occur in the absence of oestradiol and progesterone. The results further suggest that progesterone may not be associated with the mechanisms terminating behavioural oestrus in rats. Treatment with OB on the day of oestrus can prolong the duration of receptivity but only at a higher dosage than that needed for induction of receptivity.

Animals↗
PubMed1976

Cerebrospinal fluid and plasma glutamine elevation by anticonvulsant drugs: a potential diagnostic and therapeutic trap.

Administration of phenobarbitone or primidone can produce an elevation of glutamine and ornithine concentrations, together with a reduction of urea concentrations, in the fasting plasma and CSF of some infants, and in the CSF of some older epileptic patients. These two anticonvulsant drugs may interfere with the metabolic conversion of ammonia to urea, possibly by enzyme inhibition at the step of carbomoyl phosphate synthesis. The elevation of glutamine in plasma and CSF can mimic values found in some hyperammonemias. Recognition of this drug reaction can prevent erroneous diagnoses of genetically-determined urea cycle disorders and subsequent inappropriate therapy.

Adolescent↗
PubMed1976

Short arm deletion of an X chromosome, 46,XXp-.

A 27-year-old patient of short stature with primary amenorrhea and other slight Turner signs showed a 46,XX,del(X) (qter leads to p11:) karyotype, identified by a combination of fluorescence and giemsa-banding technique. By BUdR incorporation the deleted X chromosome was shown to be the late replicating one.

Adult↗
PubMed1976

Partial trisomy 2q and familial translocation t(2;12)(q31;q24).

Report is given of a boy with trisomy of the distal part of the long arm of chromosome 2 (q31 leads to ter) due to a balanced 2/12 translocation in the mother: 46,XX,t(2;12) (q31;q24). Other phenotypically normal carriers of this balanced translocation are the patients sister and grandfather. The patient shows a variety of dysplastic signs mainly of the face.

Chromosome Aberrations↗
PubMed1976

Intrachromosomal gene mapping in man: assignment of nucleoside phosphorylase to region 14cen leads to 14q21 by interspecific hybridization of cells with a t(X;14) (p22;q21) translocation.

The structural gene for purine-nucleoside phosphorylase (NP) has been assigned to a subregion of chromosome 14 by somatic cell hybridization of male and female cells containing the balanced translocation t(X;14) (p22;q21). Peripheral lymphocytes were fused to a pseudodiploid HPRT-deficient established Chinese hamster cell line. 23 primary hybrid clones (10 derived from male and 13 from female cells) were isolated and maintained in HAT selective medium. Parallel subcultures from generations 16, 24, and 40 after clonal isolation were fully karyotyped and analyzed electrophorectically for expression of the human types of NP, HPRT, G6PD, and PGK. The human NP phenotype segregated discordantly with each human chromosome except chromosome 14 and the der(14),t(X;14) translocation chromosome. In all, 8 hybrids which had retained the der(X), t(X;14) translocation chromosome under HAT selective pressure and expressed human HPRT had lost the human NP phenotype. These results indicate localization of the NP gene in region 14pter leads to 14q21.

Adenine Phosphoribosyltransferase↗
PubMed1976

Lactic acidosis in three sibs due to defects in both pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase complexes.

A Canadian Indian family is described in which three of the children were mentally retarded, and had seizures and other neurological abnormalities. They had chronic metabolic acidosis associated with elevated blood levels of lactate, pyruvate, and alanine. Two of the children excreted large amounts of pyruvic and alpha-ketoglutaric acids in the urine and had elevated plasma levels of glutamic acid and proline. Hypoglycemia occurred with fasting in two of the children. Treatment with pharmacological doses of thiamine, lipoic acid, biotin, riboflavin, and various dietary regimes was without effect. One child died at 3 1/2 months and another at 4 1/2 months; the third is still alive at 23 months of age. Enzyme assays revealed a low level of activity of both the pyruvate and alpha-ketoglutarate dehydrogenase complexes in cultured fibroblasts of one of the sibs. These patients appeared to have partial defects in the oxidation of pyruvate, as well as of alpha-ketoglutarate within the tricarboxylic acid cycle.

Acidosis↗
PubMed1975

Nonketotic hyperglycinemia. Glycine accumulation due to absence of glycerine cleavage in brain.

Glycine concentrations were measured in plasma and cerebrospinal fluid of five patients in different types of hyperglycinemia to determine why severe neurologic deterioration is confined to the so-called nonketotic form of hyperglycinemia. Glycine content and glycine-cleavage enzyme activity were also determined in brain obtained in autopsy from three of these patients. Spinal-fluid glycine concentrations were 15 to 30 times above normal in patients with nonketotic hyperglycinemia, but were normal in those with hyperglycinemias of undetermined type who had comparable elevations of plasma glycine. Glycine content was two to four times above normal in several brain regions, and brain glycine cleavage enzyme activity was absent in two patients dying of nonketotic hyperglycinemia. By contrast, glycine content was normal and glycine cleavage activity present in the brain of an infant who died of hyperglycinemia of unknown cause. These results suggest that elevated glycine levels may be harmless in blood, but lethal in brain.

Adult↗
PubMed1975

Hereditary mental depression and Parkinsonism with taurine deficiency.

An unusual neuropsychiatric disorder inherited in autosomal dominant fashion occurred in three successive generations of a family. Symptoms commenced late in the fifth decade in six affected patients and led to death in four to six years. The earliest and most prominent symptom was mental depression not responsive to antidepressant drugs or electroconvulsive therapy. This was accompanied by exhaustion, sleep disturbances, and marked weight loss. Later in the disease, symptoms of parkinsonism appeared, and respiratory failure occured terminally. The most recently affected family member was investigated biochemically late in his illness. Concentrations of taurine were greatly diminished in plasma and cerebrospinal fluid, and at autopsy, all regions of brain examined had a markedly reduced taurine content. Since taurine is a putative inhibitory synaptic transmitter, deficiency of brain taurine may possibly have caused the psychiatric and neurological manifestations of this disorder.

Age Factors↗
PubMed1975

Amino acids in human epileptogenic foci.

Free amino compounds were measured in 16 rapidly frozen epileptogenic foci excised from temporal or frontal cortex of nine patients with focal epilepsy, and in single cortical biopsy specimens obtained from 16 nonepileptic patients. Unlike the findings of a previous study, glutamic and aspartic acids were not diminished in the foci, nor was there a decrease in gamma-aminobutyric acid (GABA) or taurine levels. Glycine content was markedly elevated in two of 16 epileptogenic foci. These results do not suggest that deficiencies of GABA or of taurine, amino acids that may act physiologically as inhibitory neurotransmitters or modulators of inhibition, are causes of focal epilepsy, nor do they provide a logical basis for clinical trials of taurine in treatment of human epilepsy.

Adolescent↗