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Biomedical subjects

D Chambers

Publications and source records attributed to D Chambers.

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

Induced motion and oculomotor capture.

Three experiments investigating the basis of induced motion are reported. The proposition that induced motion is based on the visual capture of eye-position information and is therefore a subject-relative, rather than object-relative, motion was explored in the first experiment. Observers made saccades to an invisible auditory stimulus following fixation on a stationary stimulus in which motion was induced. In the remaining two experiments, the question of whether perceived induced motion produces a straight ahead shift was explored. The critical eye movement was directed to apparent straight ahead. Because these saccades partially compensated for the apparent displacement of the induction stimulus, and saccades to the auditory stimulus did not, we conclude that induced motion is not based on oculomotor visual capture. Rather, it is accompanied by a shift in the judged direction of straight ahead, an instance of the straight ahead shift. The results support an object-relative theory of induced motion.

Attention↗
PubMed1985

St. Thomas' Hospital cardioplegia for myocardial preservation during prolonged aortic cross-clamping.

The effectiveness of St. Thomas' Hospital cardioplegia for myocardial preservation during prolonged aortic cross-clamping was analyzed in a clinical series of 100 consecutive cardiac surgical patients identified as having aortic cross-clamp times greater than 120 minutes. Hospital mortality from all causes was 8%, but only one of these 8 patients succumbed from immediate primary failure of the myocardial preservation protocol. Severe but reversible low cardiac output syndrome occurred in 5 patients, and in 4 of them there had obviously been a primary failure in cardiac protection. Peri-operative, clinically "silent" myocardial infarction could be demonstrated in retrospect by electrocardiographic criteria in 3 other patients. Post-operative complications occurred in 26 patients, many of them having several complications at the same time. Paired left ventricular and right ventricular prebypass and post-bypass biopsies processed for cytochemical and biophysical investigation were available from one third of the patients. Only 2 cases showed a severe deterioration. There was lack of correlation between the duration of aortic occlusion and operative mortality rate, incidence of peri-operative infarction, and occurrence of low cardiac output syndrome post-operatively. The results thus indicate that St. Thomas' Hospital cardioplegia is a very effective means of myocardial protection during prolonged periods of aortic cross-clamping.

Adolescent↗
PubMed1983

Bone marrow transplantation for severe aplastic anaemia. A review of the Westminster experience of 24 cases.

Twenty-four patients have received bone marrow transplantation for severe aplastic anaemia at the Westminster Hospitals since 1974. Twelve patients are long term survivors. Infectious complications in association with graft rejection, graft versus host disease or prolonged neutropenia were the major cause of death. In the last 18 months the introduction of more effective conditioning regimes and Cyclosporin A as graft versus host disease prophylaxis has improved the survival rate to 85%. One patient has required regrafting for late graft failure without evidence of graft rejection.

Adolescent↗
PubMed1981

Reversal of clinical features of Hurler's disease and biochemical improvement after treatment by bone-marrow transplantation.

A one-year-old boy with type I H mucopolysaccharidosis (Hurler's disease) was given a bone-marrow transplant (BMT) from his mother in an attempt to replace the deficient enzyme, alpha-L-iduronidase (iduronidase). These is definite evidence of engraftment, the enzyme activity of the recipient's leucocytes reaching heterozygote levels within 37 days of the BMT. Graft-versus-host disease (GVHD) developed but was partially controlled by steroids. From 3-4 months after graft until the present (13 months after the graft) iduronidase activity has been present in the serum and the urine and there has been evidence of considerable degradation of glycosaminoglycans excreted in the urine. The hepatosplenomegaly has disappeared, corneal clouding has cleared, and deterioration in the child's development seems to have been arrested.

Aminoacridines↗
PubMed1981

Lack of a direct metabolic effect of fructose, 1,6-diphosphate in ischemic myocardium.

Fructose 1,6-diphosphate (FdP) reportedly protects ischemic myocardium. To determine whether this is a direct action on the heart, we used a canine model in which two coronary arteries were perfused at identical but reduced rates. Into one artery we infused FdP (total doses of 400 mg or 1.8 g) while the other received 0.9% NaCl. After 1 h, biopsies were taken from a normal region and the two ischemic regions and were analyzed for ATP, phosphocreatine (PC), and lactate content. In the 0.9% NaCl-treated ischemic tissue, ATP and PC fell to half the nonischemic levels. The FdP-treated tissue exhibited high-energy phosphate levels similar to the 0.9% NaCl-treated tissue with no significant differences between the two ischemic areas. Lactate levels in both ischemic areas were elevated threefold above nonischemic levels. Contractility studies showed that infusion of FdP directly into the coronary artery depressed contractility in both nonischemic and ischemic conditions. Our data show that, if FdP does have a protective action in ischemia, it is not through a direct action on the heart.

Adenosine Triphosphate↗
PubMed1980

The ring nature of a tiny supernumerary chromosome fragment.

We report a 5 1/2-year-old girl with a tiny supernumerary chromosome fragment found in mosaic. The ring nature of the tiny fragment was demonstrated by the detection of the characteristic products of a ring chromosome. The clinical consequence of a ring chromosome and the impact of finding a supernumerary chromosome fragment, especially in the practice of prenatal chromosome diagnosis, are discussed.

Child, Preschool↗
PubMed1979

Two cases of trisomy 12p due to rcpt (12;21)(p11;p11) inherited through three generations.

Two cases of trisomy 12p due to a familial translocation t(12;21) (p11;p11) inherited through three generations are presented. The clinical features of both affected individuals are consistent with those previously reported. Study of the NORs by silver staining showed translocation of the NOR from chromosome 21 onto the der(12) and suggested that the activity of this site has been suppressed in some carriers.

Adolescent↗
PubMed1979

Membrane-bound mitochondrial DNA: isolation, transcription and protein composition.

Mitochondrial membrane-bound DNA complex from bovine heart mitochondria lysed in the presence of Triton X-100 was isolated by differential centrifugation. The yield of "nucleoid" is about 30 microgram protein/mg mitochondrial protein. It contains about 3-5 microgram DNA/mg protein and varying amounts of RNA. The heart mitochondrial nucleoid actively synthesizes RNA. The nucleoid fraction contains about sixteen different proteins as evidenced by urea-SDS gel electrophoresis and about twenty-one proteins as evidenced by acid-urea gel electrophoresis. It appears that the nucleoid is attached to the inner membrane since it does contain cytochromes.

Animals↗
PubMed1978

Histone-produced magnesium extrusion from mitochondria and magnesium binding to histone.

Histone (60 microgram/mg mit. protein) extrudes Mg2+ from mitochondria by 30% with the utilization of endogenous substrates; in the presence of rotenone extrusion drops to about 18%. Dinitrophenol and ADP prevent this effect of histone. Mg2+ extrusion produced by histone depends on histone concentration being at a maximum (100% extrusion) at 107 microgram histone/mit. protein. It was found also that histone alone binds Mg2+ (1.6 nmol Mg2+/microgram histone).

Adenosine Diphosphate↗
PubMed1977

Translation of mRNA for glutamate dehydrogenase and spectrophotometric procedure to follow the enzyme biosynthesis.

Heterogeneous poly (A)-mRNA fraction was isolated from rat liver microsomes using phenol-chloroform extraction, millipore filtration and poly (U)-agarose affinity chromatography. Obtained fractions were characterized with respect to their secondary structure and poly (A) content. Isolated poly (A)-mRNA fraction contained high template activity for glutamate dehydrogenase in cell-free systems with microsomes or polysomes. A spectrophotometric procedure to follow enzyme biosynthesis was also developed.

Animals↗
PubMed1977

Studies on a rat liver subcellular poly A-rich RNA fraction with glutamate dehydrogenase template activity.

A heterogeneous poly A-mRNA fraction was isolated from rat liver microsomes by phenol:chloroform extraction, millipore filtration, and poly U-agarose affinity chromatography. The fractions were characterized by their secondary structures and poly A contents. From translational studies, the isolated fraction was found to have high glutamate dehydrogenase template activity in cell-free systems containing microsomes or polysomes. A spectrophotometric procedure for following enzyme biosynthesis was also developed.

Animals↗
PubMed1976

Supravalvular aortic stenosis-infantile hypercalcaemia syndrome: in vitro hypersensitivity to vitamin D2 and calcium.

The incidence of cytoplasmic metachromasia has been studied in cultures of skin fibroblasts derived from 6 cases of the syndrome of supravalvular aortic stenosis, characteristic facies, and mental retardation which in many instances represents the late normocalcaemic stage of the severe form of infantile hypercalcaemia. The percentage of metachromatic cells (mean positivity 7.3%) was significantly higher than in control cultures. The addition of vitamin D2 and calcium to culture media caused a highly significant increase in metachromatic cells (mean positivity in supplemented media 16.1%) compared with a lesser increase in controls. These findings strengthen previous suggestions that there is a genetically determined hypersensitivity to vitamin D in some cases of the syndrome. A multifactorial aetiology is proposed, dependent on a variable genetic susceptibility of fetal connective tissues to a non-physiological effect of D vitamins and a variable level of maternal vitamin D nutrition.

Adolescent↗