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Biomedical subjects

J Vincent

Publications and source records attributed to J Vincent.

At least 235 records · Page 13Linked to original sources
PubMedDate not supplied

Trimazosin: relationships between hypotensive effect, vascular responsiveness, and drug and metabolite concentrations.

The relationships between the effects on blood pressure and vascular responsiveness, and the whole blood concentration of the antihypertensive drug trimazosin and its major metabolite were investigated in six normotensive male volunteers following 100 mg i.v. and 200 mg p.o. administration. Pressor responses to intravenous phenylephrine and angiotensin II were evaluated 1-3 (early) and 5-7 h (late) after drug or vehicle administration. There was a fall in blood pressure in the erect position (maximum between 4 and 8 h) associated with a modest increase in heart rate. Following treatment with trimazosin, blood pressure fell to 100/63 mm Hg with intravenous administration and 92/63 mm Hg with oral treatment, compared with the placebo value of 114/83 mm Hg. Both oral and intravenous trimazosin caused a significant rightward shift of the phenylephrine pressor dose-response curve (p less than 0.05). There was no significant shift of the angiotensin II pressor dose responses. Using linear regression analysis, the concentration of trimazosin in whole blood showed a significant correlation with the dose ratios from the phenylephrine pressor dose responses following treatment with both intravenous (r = 0.73, p less than 0.02) and oral (r = 0.57, p less than 0.05) trimazosin. There was no such correlation using dose ratios from angiotensin II pressor dose responses. There was no correlation between the concentration of the metabolite 1-hydroxytrimazosin and dose ratios from either phenylephrine or angiotensin II pressor dose responses. These observations suggest that the predominant mechanism of action of trimazosin, at doses that reduce blood pressure in humans, is through blockade of peripheral postjunctional alpha 1-adrenoceptors.

Adult↗
PubMedDate not supplied

Molecular and cytogenetic investigations of the fragile X region including the Frax A and Frax E CGG trinucleotide repeat sequences in families multiplex for autism and related phenotypes.

We undertook molecular and cytogenetic analyses in 25 families multiplex for autism and related disorders. Three of the multiplex families exhibited fragile X, and the affected offspring all exhibited CGG triplet repeat insertion mutations in the FMR-1 gene. One of these families contained an affected pair of monozygotic female twins. Both had similar-sized CGG triplet repeat expansions, but different phenotypic manifestations. One suffered from autism and the other from mild mental retardation and marked social anxiety. PCR and Southern hybridization analysis of the CGG repeat sequences characterizing fragile X A (Frax A) and E and the methylation status of FMR-1 showed no evidence of abnormal CGG repeat expansion or FMR-1 hypermethylation in the remaining 22 multiplex families. Moreover, there was no correlation between the Frax A or E (CGG)n repeat length with affected status, nor any association with the low-level (< 3 %) expression of cytogenetic fragility at Xq27 previously reported in these families. Our findings indicate that most instances of recurrence in families multiplex for autism and related disorders are not accounted for by Frax A and E. They also indicate that the phenotypic manifestations of Frax A may be influenced by stochastic, environmental and other biological factors.

Autistic Disorder↗
PubMedDate not supplied

Clinical pharmacokinetics of prazosin--1985.

Prazosin is a selective alpha 1-adrenoceptor antagonist which is useful alone or in combination for the treatment of hypertension and heart failure. Unlike many other antihypertensive drugs, the action of prazosin appears to be closely related to its concentration in plasma or whole blood. Prazosin is variably absorbed, is subject to first-pass metabolism, and is eliminated almost entirely as metabolites of much lower hypotensive activity than the parent drug. Prazosin is highly bound to plasma and tissue proteins. The influences of renal, hepatic and cardiac disease on the disposition of prazosin are reviewed, as are the effects of pregnancy and ageing. The optimum use of prazosin in clinical practice depends on an understanding of the pharmacokinetic properties of the drug.

Aging↗
PubMedDate not supplied

[An usual observation of Bouveret syndrome (author's transl)].

An unusual observation of Bouveret syndrome is reported. It occurred in a male patient, under the usual age for this disorder, with no history of cholelithiasis. Diagnosis was only established during the surgical procedure. There were neither radio-opaque stones nor air in the common biliary duct. Attempts to opacify the fistula failed. Gastro-entero-anastomosis, which is sometimes proposed because of the patient's poor general condition, is often necessary because of the local lesions. This procedure allows to wait until the local condition improves before undertaking the complete cure during the second procedure, with considerably lesser risk.

Cholelithiasis↗
PubMedDate not supplied

[Blunt and open trauma of the heart and thoracic aorta in 26 patients (author's transl)].

Twenty-six patients with blunt or open trauma to the heart and thoracic aorta were admitted and 23 were operated on. Among 19 blunt trauma there were 15 ruptures of the aorta among which 12 were operated and 3 were not, 2 lesions of the ventricular septum, 1 coronary thrombosis and 1 rupture of the right atrium. In 7 open wounds there were 3 ventricular lesions; 3 cases of pericarditis and 1 aortic lesion. Among operated patients 1 died of a rupture of the aortic isthmus and another of a rupture of the aortic arch and left carotid artery. The 3 patients that were not operated died of a rupture of the aortic isthmus. In these cases the diagnosis must be set early and the aortography must be followed by an operation. In cases of an open wound early thoracotomy is recommended.

Adolescent↗
PubMedDate not supplied

Our personal experience with intra-aortic balloon pumping.

Intra-aortic counterpulsation (IABP) was used in 64 patients because of: 1. Low output syndrome after open heart surgery. 2. Medical refractory cardiogenic shock. 3. Elective, preoperative in ischemic heart disease. 4. Extending myocardial infarction. 5. Evolving impending infarction. In the first group in 78% hemodynamic stabilization was achieved but the survival percentage was 46%. In cardiogenic shock the results were closely related to the duration of shock, but nevertheless survival rate was low (3 from 13 patients treated). IABP was also applied as elective, preoperative support in high risk patients with ischemic heart disease (unstable angine and poor left ventricular function). In this group the rate of perioperative myocardial infarction was lower than in overall material.

Adult↗
PubMedDate not supplied

Traumatic rupture of the thoracic aorta.

The experience in the surgical treatment of traumatic rupture of the thoracic aorta is discussed. Twenty-two patients were seen from 1970 to 1980. They were divided into three groups, according to delay between injury and aortic repair: 1 degree emergency group: 16 patients; 2 degree delayed group: 3 patients; 3 degrees chronic group: 3 patients. All patients had a widened mediastinum and the aortography confirmed the diagnosis. In the first group four patients died before surgery could be started and four after aortic repair from 10 days to 6 seeks postoperatively. In the second and third group all patients survived. Of 22 cases, 21 ruptures were located at the aortic isthmus and 1 at the aortic arch. Many patients had various other injuries, skeletal, abdominal or cerebral. All, but one patient, were operated with the aid of a partial pulsatile left heart bypass to avoid cerebral hypertension and cardiac overload, and to prevent kidney and spinal cord ischemia. One patient was operated, according to the method of Crawford, with blood pressure controlled with nitroprusside. We have not observed in our patients paresis or paraplegia after surgery. The hospital mortality of the surgical treated patients was 34% in the emergency group and 0% in the delayed and chronic group. Surgical treatment is essential in emergency situation, as a complete rupture may be fatal and repair of the chronic post-traumatic false aneurysm is advocated, as their prognosis is unpredictable.

Aorta, Thoracic↗
PubMedDate not supplied

Effects of thyroid hormone on synaptogenesis in the molecular layer of the developing rat cerebellum.

In 14-day-old thyroid-deficient rats, qualitative and quantitative ultrastructural study of the cerebellar molecular layer shows that the retardation in synaptogenesis between Purkinje cell dendritic spines or excrescences and synaptic segments of parallel fibres is related to the marked hypoplasia of Purkinje cell dendritic arborizations and to the retarded development of parallel fibres rather than to the delay in the deposition of granule cells. Synaptogenesis inhibition is more marked in the inner parts of the molecular layer so that the normal "march" of synaptogenesis from the bottom of the layer upwards is distorted. This study also indicates that thyroid hormone deprivation affects synaptogenesis by interacting with growth and branching of neuronal processes and with the organization of their microtubular apparatus rather than with the differentiation of the structural specializations forming the synapses. The first corrective effect of a very low dose of thyroxine administered 24 h before sacrifice to the hypothyroid animal is observed at the level of parallel fibres and their varicosities. Purkinje cells take longer to respond to the hormone. However, their directing role in the histogenesis of the cerebellar cortex is strongly suggested. The significance of these observations with regard to the mechanisms underlying the effects of thyroid hormone on synaptogenesis and synaptic organization between Purkinje cells and parallel fibres as well as on histogenetic granule cell death is discussed.

Aging↗