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Biomedical subjects

D Samson

Publications and source records attributed to D Samson.

At least 127 records · Page 7Linked to original sources
PubMed1982

In-vitro studies of ineffective erythropoiesis in rheumatoid arthritis.

Ineffective erythropoiesis was assessed in a series of 32 patients with rheumatoid arthritis by means of a new in-vitro method which measures the release of haem from a labelled cohort of erythroblasts in culture. Haem release was significantly increased in patients with the anaemia of chronic disorders but was normal in those who were not anaemic or who had an iron-deficiency anaemia. In 2 patients with anaemia of chronic disorders haem release returned to normal after successful antirheumatic therapy. The increased ineffective erythropoiesis in patients with rheumatoid arthritis and anaemia of chronic disorders appeared to be unrelated to functional iron deficiency and was not attributable to a serum factor.

Adolescent↗
PubMed1982

Furosemide in the intraoperative reduction of intracranial pressure in the patient with subarachnoid hemorrhage.

The effect of furosemide in the intraoperative reduction of intracranial pressure was measured in 25 patients undergoing the operative repair of a ruptured intracranial aneurysm. Seven patients with similar intracranial lesions served as controls. A single bolus of 80 mg of furosemide was administered intravenously after the induction of anesthesia, and sequential measurements were made of intracranial pressure, mean arterial pressure, and arterial blood gases. A mean decrease of intracranial pressure of 56% was measured in the furosemide-treated patients, whereas the control patients demonstrated a mean decline of subarachnoid pressures of 18%. These changes are significant at the P less than 0.005 confidence level, whereas changes in mean arterial pressure, mean arterial pCO2, and base line arterial pCO2 were statistically insignificant. This study suggests that intravenous furosemide is a quick, dependable, and effective mechanism for the intraoperative reduction of intracranial pressure in the postsubarachnoid hemorrhage aneurysm patient.

Adult↗
PubMed1982

[Current methods of vascular exploration: Doppler, thermography, capillaroscopy].

According to a national study, the currently available vascular investigations give fragmentary information. Ultrasound velocimetry is usually normal, but sometimes, it reveals, early in the course of the disease, an original finding, diastolic flow. Thermography demonstrates thermic gradients in phase I, hyper- or iso-thermia in phase II and hypothermia in phase III. Capillaroscopy can demonstrate pericapillary edema, venulo-capillary stasis and tortuosities which are non-specific criteria, only significant by their associations. This study needs to be pursued in order to define the course of these vasomotor changes.

Angiography↗
PubMed1981

Determination of delta-aminolaevulinic acid synthase activity in human bone marrow using high performance liquid chromatography.

A high performance liquid chromatographic (HPLC) method is described for the rapid and specific determination of the activity of the enzyme delta-aminolaevulinic acid synthase (ALA-S) in mitochondria prepared by sonication of human bone marrow cells. After incubation with 14C-alpha-ketoglutarate the 14C-delta-aminolaevulinic acid (ALA) formed is converted to a pyrrole derivative, 2-methyl-3-carbethoxy-4-(3-propionic acid) pyrrole. This is isolated by reversed-phase ion-pair chromatography on a Hypersil-SAS column with methanol-water (45:155, v/v) in the presence of 0.005 mol/l 1-heptanesulphonic acid (PIC B-7) as the mobile phase. The radioactivity of the isolated pyrrole is determined by scintillation counting. The optimal substrate concentration and pH were 0.17 mmol/l alpha-ketoglutarate and pH 7.4, with an optimal period of sonication of 18s. Under these conditions ALA production was proportional to the concentrations of erythroblasts in the initial sample and was linear with time up to 60 min. The addition of pyridoxal phosphate (PLP) did not affect ALA-S activity in normal subjects. The mean ALA-S activity in 10 haematologically normal control subjects was found to be 318.8 pmol.10-6 erythroblasts.h-1 (S.D. 125.8, range 193-444.6).

5-Aminolevulinate Synthetase↗
PubMed1981

Neurosurgical applications of the cyanoacrylate adhesives.

The cyanoacrylate adhesives are a biologically heterogenous group, some of which are potentially valuable additions to the neurosurgical armamentarium. The commercially available cyanoacrylates usually contain the more toxic methyl and ethyl monomers. The safe butyl monomer, isobutyl 2-cyanoacrylate, is approved in the United States by the Food and Drug Administration for investigational use only. Isobutyl 2-cyanoacrylate may prove to be useful for the extravascular reinforcement of intracranial aneurysms and for the intravascular occlusion of carotid-cavernous fistulae. Safe and effective alternatives exist for the management of these two problems. The sealing of certain cerebrospinal fluid fistulae and the intravascular occlusion of certain arteriovenous malformations may be more effectively accomplished with isobutyl 2-cyanoacrylate than with other currently available techniques. The ultimate role of this and of other as yet untested cyanoacrylates in neurosurgery remains to be determined.

Animals↗
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↗