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Biomedical subjects

E Robertson

Publications and source records attributed to E Robertson.

12 recordsLinked to original sources
PubMed1992

Transport and membrane binding of the glutamine analogue 6-diazo-5-oxo-L-norleucine (DON) in Xenopus laevis oocytes.

We have examined transport and membrane binding of 6-diazo-5-oxo-L-norleucine (DON, a photoactive diazo-analogue of glutamine) and their relationships to glutamine transport in Xenopus laevis oocytes. DON uptake was stereospecific and saturable (Vmax of 0.44 pmol/oocyte.min and a Km of 0.065 mM). DON uptake was largely Na+ dependent (80% at 50 microM DON) and inhibited (greater than 75%) by glutamine and arginine (substrates of the System B0,+ transporter) at 1 mM. Glutamine and DON show mutual competitive inhibition of Na(+)-dependent transport. Preincubation of oocytes in medium containing 0.1 mM DON for 24 or 48 hr depressed the Vmax for System B0,+ transport (as measured by Na(+)-dependent glutamine uptake), this effect was highly specific (neither D-DON nor the System B0,+ substrates glutamine and D-alanine showed any independent effect) and required Na+ ions. Glutamine (1 mM in preincubation medium) protected transport from inhibition by DON. The possibility that specific inactivation of System B0,+ by DON reflects attachment of DON to the transporter was tested by examining the binding of [14C]DON to Xenopus oocyte membranes. Oocytes incubated in 100 mM NaCl in the presence of [14C]DON for up to 48 hr showed 2.4-fold higher 14C-binding to membranes than oocytes incubated in choline chloride. Na(+)-dependent DON binding (31 +/- 11 fmol/micrograms membrane protein) was suppressed by external glutamine, arginine or alanine and was largely confined to a membrane protein fraction of 48-65 kDa (as assessed by SDS-polyacrylamide gel electrophoresis). The present studies indicate that DON and glutamine uptake in oocytes are both mediated by System B0,+ and demonstrate the DON binding to a particular membrane protein fraction is associated with inactivation of the transporter, offering the prospect of using [14C]DON as a covalent label for the transport protein in order to facilitate its isolation and subsequent biochemical characterization.

Animals↗
PubMed1992

Effect of spirapril on left ventricular hypertrophy due to volume overload in rats.

The effect of the angiotensin-converting enzyme (ACE) inhibitor spirapril on structural and functional parameters of volume-overloaded rat hearts was evaluated in a time-course study. Left ventricular hypertrophy (LVH) was induced by graded disruption of the aortic valve in male Wistar rats. Four weeks later, structural (LV mass and LV wall thickness) as well as functional parameters [LV end-systolic and end-diastolic volumes, stroke volume (SV), ejection fraction (EF)] were determined in anesthetized animals by magnetic resonance imaging (MRI). The rats were then divided into two groups, one of them receiving spirapril (10 mg/kg/day) in food. LV parameters were evaluated by MRI at 4, 18, 25, and 32 days after treatment was started. MRI analysis before the start of treatment showed that both groups had developed a similar degree of eccentric LV hypertrophy. Similarly, LV wall thickness, end-systolic and end-diastolic volumes, SV, and EF did not differ between the groups. Treatment with spirapril resulted in stable LV weight during the follow-up period of 32 days, whereas the untreated group showed a significant steady increase in heart weight. LV end-diastolic volume, LV end-systolic volume, and SV were smaller in the spirapril group when measured after 25 and 32 days, but only the difference in end-diastolic volume reached statistical significance. LV wall thickness and EF were not affected by spirapril. After the last MRI determinations, blood pressure (BP) and the response to angiotensin I (ANGI) were measured in conscious animals. Systolic BP (SBP) and mean arterial pressure (MAP) were significantly lower in spirapril-treated rats, and the dose-response curve to ANGI was shifted to the right.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1990

Pathology of hepatic peroxisomes and mitochondria in patients with peroxisomal disorders.

The morphology of hepatic peroxisomes in five patients with metabolic disorders believed to be due to inherited defects of peroxisomal function or biogenesis is described. Electron microscopy and cytochemical staining for catalase were used to identify peroxisomes in two boys with infantile Refsum's disease (IRD), a girl with autopsy confirmed neonatal adrenoleukodystrophy (NALD), and two boys with pseudo-Zellweger syndrome (PZS). In the patients with IRD and NALD hepatic peroxisomes were significantly reduced in size and number and contained electron dense centres. In the liver of the patients with PZS the peroxisomes were enlarged. Morphologically abnormal peroxisomes were also detected in autopsy tissue from one boy with PZS using electron microscopy. Lamellar-lipid inclusions and mitochondria with crystalline inclusions and/or abnormal cristae are also described in two patients, one with IRD, the other with NALD.

Adrenoleukodystrophy↗
PubMed1979

Brain damage in infancy and dietary vitamin B12 deficiency.

A case of the exclusively breast-fed infant of a vegetarian mother is reported. Neurological deterioration commenced between three and six months of age, and progressed to a comatose premoribund state by the age of nine months. Investigations revealed a mild nutritional vitamin B12 deficiency in the mother, and a very severe nutritional B12 deficiency in the infant, with severe megaloblastic anaemia. Treatment of the infant with vitamin B12 resulted in a rapid clinical and haematological improvement, but neurological recovery was incomplete. Evidence is presented that dietary B12 deficiency was the sole cause of the infant's deterioration, and the literature relating to the condition is reviewed. It is recommended that all strict vegetarians (vegans), especially women in the child-bearing age group, take vitamin B12 supplements.

Anemia, Megaloblastic↗
PubMed1979

Electron microscopy of skin and peripheral blood lymphocytes in infantile (Santavuori) neuronal ceroid lipofuscinosis.

Skin punch biopsies and peripheral blood lymphocyte preparations from two siblings with early infantile (Santavuori) neuronal ceroid lipofuscinosis have been examined by electron microscopy. In both cases characteristic osmiophilic inclusion bodies were found in various cells in the skin and in lymphocytes. In one case, lymphocyte inclusions were detected before the onset of any symptoms as a result of a family study. This indicates the possibility of screening lymphocytes of siblings of affected patients as a result of a family study. This indicates the possibility of screening lymphocytes of siblings of affected patients with a view to early detection of the disorder.

Ceroid↗
PubMed1979

Effect of an elemental diet (Vivonex) on the absorption abnormalities and histological appearances of the jejunum in untreated adult coeliac disease.

The effect of an elemental diet (Vivonex) together with a gluten-free diet on the absorption of water, sodium and chloride in the jejunum was studied in 4 patients with untreated adult coeliac disease before and after a 1-month course of therapy. The morphology of the jejunum was also studied by jejunal biopsy taken at the same time as the intestinal perfusion. The results were compared with those obtained in 4 patients with adult coeliac disease treated with a gluten-free diet alone. No marked improvement was noted in the transportation of water, sodium and chloride after either treatment with Vivonex and a gluten-free diet or after a gluten-free diet alone, and no marked histological changes were found. Clinical improvement occurred in both groups of patients, in that the diarrhoea improved in all patients and they generally felt better. There appears to be no additional advantage of using an elemental diet with a gluten-free diet in the initial management of adult coeliac disease.

Adult↗
PubMed1978

Galactosaemia: case for neonatal screening illustrated by recent Australian experience.

The varied presentation and clinical features of classical galactosaemia are illustrated by the case histories of seven babies born in Western Australia since January, 1962, and of two babies born in South Australia in whom diagnosis was made as a result of adding galactosaemia to the Guthrie screening programme in October, 1974. All were shown to have a severe deficiency of galactose-1-phosphate uridyl transferase in their red blood cells. We compare our findings with those in 10 galactosaemic babies born in Victoria over a similar period, and show that in both groups these were two main modes of onset: acute and insidious. Jaundice and Escherichia coli infection were prominent in the 13 babies with an acute onset of galactosaemia, while poor weight gain, intermittent vomiting and cataracts were features of the five babies with an insidious onset. An enlarged liver was usually found in both groups. We discuss the various approaches to neonatal screening of galactosaemia in the light of experience in Massachusetts and South Australia. The use of cord blood can be expected to lead to diagnosis before babies with acute onset become ill, while the use of blood collected at five days for the Guthrie test avoids the collection of another routine sample for a relatively rare disorder. The result of red cell transferase assays of parents and siblings of our patients are discussed in relation to their implication for genetic counselling. The relevance of antenatal diagnosis to the prevention of possible intrauterine damage to an affected fetus is pointed out.

Australia↗
PubMed1977

A visual guidance program: evaluation report.

A group of 80 fourth-grade pupils were administered visual tests to identify poor eye synchronization. The tests were given at Ruby Thomas Elementary School, Las Vegas, Nevada during February 1971 by Drs. Fred Erlich and Harvey Ohriner. Pupils with unsatisfactory eye synchronization were divided into two groups, a treatment and non-treatment or control group. A second control group was randomly selected from pupils with satisfactory eye synchronization. Visual guidance exercises were given to the treatment group. Post test reading tests showed significant gains in reading for the treatment group. Control groups showed non-significant gains.

Child↗
PubMed1976

In vitro attachment of trypanosomes to plastic.

Description of an in vitro system for the study of the attachment of trypanosomes to polystyrene flasks by means of hemidesmosomes. This type of attachment, whose significance is so far unknown, reproduces a natural stage in the life cycle of medically important trypanosomatid flagellates in their vector.

Cell Adhesion↗