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Biomedical subjects

D Samson

Publications and source records attributed to D Samson.

At least 145 records · Page 8Linked to original sources
PubMed1981

Intravascular use of isobutyl 2-cyanoacrylate: Part 1 Treatment of intracranial arteriovenous malformations.

The intravascular use of the rapidly polymerizing acrylic compound, isobutyl 2-cyanoacrylate (IBC), in 10 patients with intracranial arteriovenous malformations (AVMs) is described. The monomer was introduced into each malformation at craniotomy using angiographic control and microvascular dissection technique to identify, isolate, and inject the major components of each vascular lesion while attempting to preserve normal arterial circulation. Postoperative angiography was used routinely to evaluate the results of IBC embolization. Four patients underwent the injection and immediate surgical excision of an intracranial AVM, and 6 underwent injection alone; 3 of the latter had residual malformation demonstrated on postoperative angiography, and 1 of these patients had the remnants of her malformation occluded by a second embolic procedure. There was no operative mortality nor permanent neurological morbidity. Three patients suffered transient neurological dysfunction in the immediate postoperative period.

Adult↗
PubMed1981

Intravascular use of isobutyl 2-cyanoacrylate: Part 2 Treatment of carotid-cavernous fistulas.

The intravascular use of the rapidly polymerizing acrylic compound isobutyl 2-cyanoacrylate in four patients with carotid-cavernous fistulas is described. The monomer was injected into the cavernous sinus at craniotomy after the intraoperative angiographic identification of the fistula site and the origin of its venous drainage. All patients had postoperative angiographic documentation of fistula closure and confirmed carotid artery patency. There was no operative mortality or permanent neurological morbidity. Two patients (50%) suffered transient dysfunction in the immediate postoperative period of one of the cranial nerves that transit the cavernous sinus.

Adult↗
PubMed1981

A simple in vitro method for the assessment of ineffective erythropoiesis.

A simple in vitro method has been developed for the assessment of ineffective erythropoiesis by measuring the release of heme from a labeled cohort of erythroblasts in short-term suspension culture. The release of labeled heme was shown to correlate with the death of erythroblasts in culture determined by cell counting. Heme release was markedly increased in conditions where there is known to be excessive ineffective erythropoiesis, while in hematologic disorders where ineffective erythropoiesis is thought to be normal, heme release was within the normal range.

Adult↗
PubMed1980

Unruptured cerebral aneurysms presenting as recurrent transient neurologic deficits.

Recurrent transient neurologic deficits were evaluated clinically in four patients. In three patients, the symptoms included recurrent transient homonymous hemianopia, episodic weakness and numbness of the left arm and leg, and recurrent sudden loss of speech and of strength in the right arm. In these three patients, the episodes were first thought to be transient ischemic attacks (TIAs). A fourth patient had repeated confusional spells, in which a recurrent musical theme excluded other thoughts. This was associated with dizziness and difficulty in naming. A partial complex seizure was thought responsible. In each of the cases the symptoms lasted less than 30 minutes and were not associated with loss of consciousness, headache, or stiff neck. Electroencephalogram (EEG), brain scan, lumbar puncture, and computed tomography (CT) scan were normal. In all patients, cerebral arteriography unexpectedly revealed an unruptured cerebral aneurysm. The locations of the aneurysms were appropriate to the symptoms, which remitted in the three patients treated surgically for the aneurysm. Although the pathophysiology is uncertain, an ischemic process may be implicated.

Adult↗
PubMed1979

Nuclear requirement of post-maturational cortical differentiation of amphibian oocytes: effects of cycloheximide.

Cycloheximide induced a complex series of alterations in the cortical cytoplasm of amphibian (Rana pipiens) oocytes undergoing steroid induced nuclear and cytoplasmic maturation in vitro. The morphological changes were described and the role of nuclear-cytoplasmic interactions in the induction of these changes was investigated in intact, enucleated and enucleated-reinjected oocytes. Three stages of cortical changes were ascertained on the basis of: localized alterations at the animal pole, redistribution of pigment and localized contractility (furrow formation) primarily along the animal:vegetal pole axis. The extent and type of cortical alterations varied depending upon the time at which oocytes were examined following hormonal stimulation and cycloheximide treatment. Cycloheximide did not produce cortical alterations in non-hormone treated oocytes nor in steroid treated oocytes until after germinal vesicle breakdown. Nuclear and cytoplasmic maturation and the appearance of cortical alterations were all inhibited when cycloheximide was added to oocytes at the time of steroid treatment. Cycloheximide induction of cortical alterations occurred only after the inhibitor was no longer effective in preventing germinal vesicle breakdown. Enucleated oocytes underwent cytoplasmic maturation in response to the steroid but exhibited no cortical alterations following the delayed addition of cycloheximide. Simultaneous administration of cycloheximide and steroid to enucleated oocytes inhibited cytoplasmic maturation and all observable cortical alterations. Reinjection of nuclear material into enucleated oocytes restored the ability of cycloheximide to induce cortical alterations following steroid induction of cytoplasmic maturation. Without steroid treatment, such reinjected oocytes did not exhibit cortical changes in response to cycloheximide. The data demonstrate that the nucleus is required for and contains a factor(s) which controls the cycloheximide response and post-maturation differentiation of the oocyte. The maturational changes in the cortical cytoplasm appear to be dependent on the intermixing of the germinal vesicle nucleoplasm materials with mature cytoplasm following germinal vesicle breakdown. The results further suggest that the cortical effects of cycloheximide are dependent upon the initiation of protein synthesis during this period of oocyte development. The significance of these observations and experimental studies are discussed in relation to current understanding of the molecular mechanisms controlling meiosis induction and the composition of the germinal vesicle.

Animals↗
PubMed1977

Reversal of ineffective erythropoiesis in pernicious anaemia following vitamin B12 therapy.

Ineffective erythropoiesis was quantitated in a series of patients with pernicious anaemia at different times in relation to vitamin B12 therapy by measuring the incorporation of [15N]delta aminolaevulinic acid and [15N]glycine into early labelled bilirubin. Prior to therapy ineffective erythropoiesis was grossly increased but this was reversed within 24 h of giving vitamin B12, suggesting that most of the existing megaloblasts are enabled to mature into circulating red cells.

Aged↗
PubMed1977

Role of ineffective erythropoiesis in the anaemia of rheumatoid arthritis.

The importance of inadequate haemoglobin synthesis and ineffective erythropoiesis in the anaemia of rheumatoid arthritis was studied by measuring the incorporation of 15N glycine into haemoglobin haem and early labelled bilirubin in a patient with severe anaemia before and after response to gold therapy. Initially, total erythroid haem turnover was decreased but haem turnover due to ineffective erythropoiesis was markedly increased, accounting for 29% of total erythroid haem turnover. Gold therapy resulted in marked clinical improvement, accompanied by a rise in haemoglobin to normal. Total erythroid haem turnover increased and the percentage ineffective erythropoiesis fell to normal. Ineffective erythropoiesis may thus be an important reversible factor in the production of the anaemia of rheumatoid arthritis.

Anemia↗
PubMed1977

Congenital dyserythropoietic anaemia: response to splenectomy and quantitation of ineffective erythropoiesis.

The clinical and haematological features of an unusual case of congenital dyserythropoietic anaemia are described. There was a pronounced haemolytic component to the anaemia, with a mean cell life of five days, and a remarkable response to splenectomy. Measurement of the incorporation of 15N glycine into the haem of circulating red cells and into bilirubin showed that haem turnover due to ineffective erythropoiesis was increased 45 times compared with a control group (11.63 mg/kg/day, NR = 0.26 + 0-10) and represented 51% of total erythroid haem turnover.

Anemia↗
PubMed1977

Cerebral revascularization for transient ischemic attacks.

Thirty-one patients with cerebral transient ischemic, attacks and ipsilateral internal carotid artery occlusion without contralateral internal carotid artery occlusion or stenosis were treated with a surgical anastomosis between a superficial temporal artery and a cortical branch of the middle cerebral artery of the symptomatic hemisphere. The anastomosis was successful in 28 patients. Recurrent transient ischemic attacks were abolished in 23 patients and reduced in three. Two patients, one with a patent anastomosis, had strokes during the follow-up period. Of seven patients who refused the operation, two had strokes, two noted a reduction of transient ischemic attacks, two noted no change, and one became asymptomatic.

Adult↗
PubMed1976

Quantitation of ineffective erythropoiesis from the incorporation of [15N] delta-aminolaevulinic acid and [15N] glycine into early labelled bilirubin. I. Normal subjects.

The incorporation of [15N] glycine into early labelled bilirubin and haemoglobin haem was measured in four haematologically normal subjects, using the clearance of [14C] bilirubin to measure total bilirubin production rate. Hepatic haem turnover was calculated from the incorporation of [15N]=sigma-aminolaevulinic acid into early labelled bilirubin. From the exprimental data previously published data in normal subjects a method is derived for the quantitation of ineffective erythropoiesis which can be applied to similar studies in patients with haematological disorders.

Aged↗
PubMed1976

Quantitation of ineffective erythropoiesis from the incorporation of [15N] delta-aminolaevulinic acid and [15N] glycin into early labelled bilirubin. II. Anaemic patients.

The incorporation of [15N]delta-aminolaevulinic acid and [15N glycine into haemoglobin haem and early labelled bilirubin was measured in subjects with various haematological disorders. The clearance of [14C bilirubin was used to measure bilirubin production rate, and the magnitude of the various sources of bilirubin production and the percentage ineffective erythropoiesis were calculated. Ineffective erythropoiesis was found to be a major factor in the production of the anaemia in patients with the following disorders: megaloblastic anaemia associated with the Lesch-Nyhan syndrome, thalassaemia intermedia, sideroblastic anaemia, and the anaemia of chronic disorders. In three patients with iron-deficiency anaemia ineffective erythropoiesis was increased, but was of minor importance in the production of the anaemia, while in two patients with aplastic anaemia and one with macrocytosis of alcoholism there was no increase in ineffective erythropoiesis.

Adolescent↗
PubMed1975

Erythraemia due to haemoglobin San Diego.

A 63-year-old man with erythraemia was found to have a high affinity haemoglobin which was subsequently identified as Hb San Diego beta 109 (G11) Val leads to Met, recently described in a Filipino family (Nute et al, 1974). The oxygen affinity of the haemolysates was increased approximately two-fold at pH values between 6.04 and 7.90. The n value was nearly normal (2.5-2.9) in the upper range of saturation (70-95% oxygenation) but was somewhat diminished (1.9-2.1) below this range. In vitro biosynthesis of globin by reticulocytes showed that there was balanced synthesis of alpha and beta chains (alpha:beta ratio = 1).

California↗
PubMed1975

Effect on primary Rh immunization of delayed administration of anti-Rh.

An intramuscular injection of 100 mug of anti-Rh, given 13 days after an intravenous injection of 1 ml of Rh-positive red cells appeared to suppress primary Rh immunization: at 6 months, none of thirteen subjects so treated had detectable anti-Rh in their plasma, whereas anti-Rh was present in five out of twelve control subjects injected with Rh-positive cells alone (P equals 0.015, Fisher's exact test, one-tailed). Primary immunization was not suppressed in all treated subjects since, following a second injection of Rh-positive cells, 7-day survival was subnormal in three subjects, all of whom had anti-Rh in their plasma after a further 2 weeks. In three other treated subjects, primary Rh immunization appeared to be completely suppressed: survival was normal, or initially normal, following a second injection of Rh-positive cells and anti-Rh was detectable only after a third injection.

Antibody Formation↗