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Biomedical subjects

S M Pueschel

Publications and source records attributed to S M Pueschel.

At least 73 records · Page 4Linked to original sources
PubMed1985

Biological and behavioural assessments of young rhesus monkeys after intrauterine exposure to high phenylalanine concentrations.

Nineteen pregnant Macaca mulatta were fed a special diet throughout the gestational period in an attempt to render them hyperphenylalaninaemic. Group C (control group) received a regular diet, group Lo was given a 'low' phenylalanine diet, group Me a 'median' phenylalanine diet, and group Hi a 'high' phenylalanine diet. Nearly all monkeys had an uncomplicated pregnancy and an uneventful delivery. Biological measurements were obtained shortly after the birth of the infants and behavioural assessments were done when the offspring were between 6 and 18 months of age. The results of the biological and behavioural evaluations revealed that there was no statistically significant difference among the respective study groups. We concluded that a combination of factors inherent in an imperfect animal model may account for the negative results of this study.

Animals↗
PubMed1985

Neurological findings in patients with the fragile-X syndrome.

We report two brothers with previously unexplained mental retardation and seizures who had dysmorphic facial features, macro-orchidism, and a fragile site at the X chromosome. This recently described syndrome is the second most common chromosome aberration associated with mental retardation after Down's syndrome. In order to determine the prevalence of seizures and the frequency of specific neurological features, we studied a total of 17 patients with the fragile X syndrome. 41% had grand mal seizures; 41% had extensor plantar responses; 47% had hyperactive behaviour and 65% exhibited stereotypics; 59% had incoordination and 35% had blepharospasm. We emphasise the need for chromosome analysis of patients with unexplained mental retardation, specific phenotypic abnormalities, and large testes.

Adult↗
PubMed1985

Fetomaternal placental transfer mechanisms of aromatic amino acids in Macaca mulatta.

We investigated aromatic amino acid transfer mechanisms from fetus to mother in third-trimester pregnancies in rhesus monkeys after the administration of radioactive phenylalanine to the fetal circulation. The results indicated that fetomaternal transfer takes place mainly by facilitated diffusion via specific membrane carriers. This mechanism might participate in regulating amino acid concentrations in the fetus.

Amino Acids↗
PubMed1984

X-linked recessive myotubular myopathy: I. Clinical and pathologic findings in a family.

Four neonatal deaths in one family were due to X-linked myotubular myopathy. The characteristic alterations in muscle, described in three cases, are marked fiber hypotrophy, size variability, and the presence of internal nuclei or pale areas. The diagnosis can be verified only by obtaining a careful genetic history. Previous occurrence of male neonatal death or stillbirth, or of hypotonia and respiratory insufficiency, is critical in the identification of suspected cases. There is morphologic justification for retaining the name "myotubular myopathy" to distinguish this X-linked disorder from other congenital conditions involving muscle weakness that have similar morphologic features.

Female↗
PubMed1984

Symptomatic atlantoaxial subluxation in persons with Down syndrome.

In a prospective study 40 of 236 individuals with Down syndrome were found to have atlantoaxial instability. Whereas most of the 40 affected children were asymptomatic, seven patients exhibited various neuropathology. Historical data, neurologic findings, radiologic interpretations, and surgical management of these seven patients are described in detail. In addition, case reports of other individuals with Down syndrome and symptomatic atlantoaxial subluxation from the literature were analyzed. We conclude that early identification of these patients and appropriate surgical management, including reduction of the subluxation and posterior cervical spine fusion, will in most instances result in a favorable outcome; however, patients with long-standing symptoms and marked neuronal damage show no or only little improvement postoperatively.

Adolescent↗
PubMed1983

Nonketotic hyperglycinemia: clinical, biochemical, and therapeutic considerations.

The salient features of nonketotic hyperglycinemia include apnea, feeding difficulties, lethargy, seizures, abnormal muscle tone and reflex activity, significant developmental delay, and, in most instances, early death. The pathogenesis of the biochemical defect leading to increased glycine concentration in blood, urine, and CSF is likely to concern derangements of the glycine cleavage enzyme and/or transport mechanisms of glycine. Our current state of knowledge of this disorder is incomplete. Therapeutic attempts, as described in Table 2, have been largely unsuccessful. Further basic research on the underlying biochemical perturbation, including additional documentation of the glycine cleavage enzyme deficiency patterns, of substrate inhibition of key metabolic pathways, and of glycine transport aberrations, as well as investigations of new pharmacologic approaches, will be a challenge for investigators in this field. It is hoped that new knowledge in these areas will eventually lead to reduction of morbidity and mortality in children with nonketotic hyperglycinemia.

Amino Acid Metabolism, Inborn Errors↗
PubMed1983

Neurophysiological, psychological, and nutritional investigations during discontinuation of the phenylalanine-restricted diet in children with classic phenylketonuria.

Assessment of cortical sensory and psychological functions in children with classic phenylketonuria during the time period of diet discontinuation did not uncover any significant changes when pre-diet and post-diet termination data were compared. Analysis of relationships among the study variables found that children who had adequate dietary control and who were of average or above average intelligence displayed normal somatosensory evoked potentials (SEP) whereas those children with less adequate dietary control and lower IQ scores had atypical SEP waveforms.

Child, Preschool↗
PubMed1983

Placental transfer of aromatic amino acids in non-human primates.

Macaca fascicularis (crab-eating monkeys) underwent an operative procedure at 120 to 130 days of pregnancy that allowed fetal blood sampling. During subsequent experiments L-phenylalanine and p-chlorophenylalanine were injected into the maternal circulation. Blood obtained from mother and fetus revealed that phenylalanine is actively transported across the placenta and hence is markedly increased in the fetus if the maternal blood phenylalanine concentration is below the "saturation" level of 1.82 mM to 2.12 mM. The results of these studies which provide a better understanding of placental transport mechanisms of aromatic amino acids will be of assistance in future management of pregnant phenylketonuric females.

Amino Acids↗
PubMed1983

Placental transfer of phenylalanine in Macaca mulatta and Macaca fascicularis.

We investigated placental transport mechanisms of phenylalanine in Macaca mulatta and Macaca fascicularis. In the beginning of the third trimester we administered i.v. phenylalanine and p-chlorophenylalanine to pregnant animals. Initial higher phenylalanine concentrations were observed followed by a rapid decrease in both rhesus mothers and fetuses when compared with phenylalanine levels in fascicularis mothers and fetuses. In general, however, placental transfer mechanisms of phenylalanine did not differ significantly between the two species.

Animals↗
PubMed1982

Effect of exercise on serum creatine kinase in carriers of Duchenne muscular dystrophy.

In order to evaluate the effect of exercise on serum creatine kinase levels, blood samples were obtained from 17 normal females and 12 Duchenne muscular dystrophy carriers before and 9 hours after moderately strenuous exercise. The results revealed that after exercise serum creatine kinase levels may be better indicators of carrier status than resting levels. The mean serum creatine kinase levels before and after exercise, as well as the mean increases, were found to be significantly greater in Duchenne muscular dystrophy carriers than in normal control subjects.

Adult↗
PubMed1982

A study of placental transfer mechanisms in nonhuman primates using [14C]phenylalanine.

Placental transfer mechanisms were investigated in pregnant Macaca Fascicularis and Macaca mulatta during the gestational age of 120 to 130 days. These primates underwent an operative procedure that allowed continuous fetal blood sampling. The administration of [14C]phenylalanine into the maternal circulation revealed a significant increase of radioactive material in the fetal circulation, indicating an active placental transport mechanism unidirectional to the fetus. When [14C]phenylalanine was injected into the fetus, radioactive aromatic amino acids in the maternal circulation increased only slightly over time, resembling a simple diffusion process.

Animals↗
PubMed1981

Atlanto-axial instability in children with Down syndrome.

One hundred fifty-eight patients with Down syndrome underwent roentgenologic examinations of the cervical spine in neutral position, in hyperflexion, and in hyperextension. Fifteen children with Down syndrome were found to have a distance between the joint surfaces of 5 mm and more. The majority of these children were asymptomatic, one child displayed hyperactive deep tendon reflexes and two children were symptomatic and underwent surgery.

Adolescent↗