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Biomedical subjects

G Martin

Publications and source records attributed to G Martin.

At least 307 records · Page 17Linked to original sources
PubMed1989

Morphological and morphometric changes in revascularised bowel grafts reconstructing the cervical oesophagus.

Revascularised grafts of jejunum and colon have been used to reconstruct the cervical oesophagus in dogs. The grafts were examined at 2 months to assess their morphological and morphometric behaviour in their new position in the oesophagus. The colonic grafts appeared to adapt completely, while the jejunal ones manifest persisting mucosal changes attributable to their new environment.

Animals↗
PubMed1989

Ventricular fibrillation detection by autocorrelation function peak analysis.

UNLABELLED: The use of reliable automatic ventricular fibrillation (VF) recognition techniques is critical in performing external automatic defibrillation. The authors' objective was to develop a method to detect VF and life-threatening arrhythmias, based on direct and simple peak analysis of the autocorrelation function (ACF). This method may differentiate between fibrillating and nonfibrillating rhythms, and in the first case between "course" and "fine" VF. ECG records during ventricular tachycardia (VT) and VF were obtained from patients during cardiac surgery. Segments 4 sec long were selected from tapes and digitized at 200 Hz, then split into three groups (VT, VF regular waveform, and VF irregular waveform). The positive peak P(j) of the ACF was defined as the maximum value between two function zeros, and RPL(j) represents the relation between P(j) and twice their own standard error. Parameter TR(1) was defined as the relation between P(1) width and the time of occurrence. ACFs were computed for the entire sample; RPL(j), D(j) = RPL(j) - RPL(j + 1), and TR(1) were calculated for every record. The results indicate that: (A) If RPL(1) greater than 1.2 and (1.6 greater than or equal to RPL(2) greater than 1) and (RPL(3) greater than 0.6 and D(1) greater than 0), then consider VT; (B) If (1.2 greater than or equal to RPL(1) greater than or equal to 1) and (1 greater than or equal to RPL(2) greater than or equal to 0.9) and D(1) greater than 9, then consider VT or VF with very regular waveform; (C) If (RPL(1) less than or equal to 1.8 and RPL(2) less than 0.9) or (RPL(2) less than 1.5 and D(1) less than 0) or RPL(3) less than 0.6, then consider VF. When 0.3 less than TR(1) less than 0.8, the underlying arrhythmia is VF or VT, and when it is outside this range, it is likely to be a supraventricular rhythm. CONCLUSIONS: (A) RPL(j) parameters have a high specificity for discriminating between VT and VF. The method is reliable and simple. (B) The TR(1) parameter together with RPL(j) allow discrimination between supraventricular tachycardias and ventricular originated tachyarrhythmias. (C) Further analysis must be done using problem-oriented arrhythmias data bases.

Data Interpretation, Statistical↗
PubMed1989

The ADONIS experiment.

The background to the setting up and implementation of the ADONIS project is described. Ways in which ADONIS might benefit both document supply centres and smaller organizations such as biomedical libraries are suggested. Particular attention is paid to economic considerations.

Commerce↗
PubMed1989

Perhexilene: effects on hepatic lysosomal function in rats.

1. Perhexilene, a long-acting anti-anginal drug, can induce adverse effects on the liver which may be dose-dependent. At high concentrations, perhexilene causes marked morphological changes in hepatocyte lysosomes. The current study examined the effect of 'therapeutic' doses of perhexilene on hepatic lysosomal function, particularly the biliary release of lysosomal enzymes, using an isolated perfused rat liver (IPRL) model. 2. Pharmacokinetic studies demonstrated that clearance of single doses of perhexilene by the perfused rat liver was dose-dependent and established a 'therapeutic' dose of 0.6 mg using the IPRL. A 5 day pretreatment regimen of 20 mg/kg per day was shown to produce 'therapeutic' perhexilene concentrations of 150-210 ng/ml. 3. At perhexilene concentrations equating the 'therapeutic' range in man, the major effect of perhexilene was at the biliary pole of the hepatocyte. In 5 day pretreatment dose studies, lysosomal enzyme excretion into bile was markedly increased. In single dose studies, the increase in biliary lysosomal enzyme output partially reflected an increase in bile water production which was not seen with the 5 day pretreatment regimen. Hepatic and perfusate lysosomal enzyme activities were not affected. 4. This selective effect of perhexilene on hepatocyte-to-bile lysosomal excretion may reflect intracellular lysosomal drug localization.

Acetylglucosaminidase↗
PubMed1989

Malignant angioendotheliosis--an unusual cause of stroke.

We report a case of malignant angioendotheliosis in a 63-year-old female who presented with a right hemiparesis. This diagnosis should be considered when multi-focal neurological signs develop in association with a progressive deterioration of mental state and conscious level.

Brain Ischemia↗
PubMed1989

A comparison of the rheologic properties of neonatal and adult blood.

A number of studies have indicated that the rheologic properties of neonatal blood are different from those of the adult. The frequent administration of blood components to the neonate during intensive care make it important that these differences be established and their causes understood. The purpose of this study was to make a detailed comparison of the rheologic properties of neonatal and adult blood, with particular emphasis on low shear rate viscosity and rouleaux-related phenomena. The viscometric data was obtained from seven preterm (PT) and 18 normal term (NT) babies and compared with those from 18 adults (A). In the present study, viscometry was performed over a wide range of shear rates, from about 0.3 to 130 s-1, and the low shear rate data were compared with direct measurement of rouleaux formation using the Myrenne Erythrocyte Aggregometer. A major factor leading to the viscometric differences observed was the high hematocrit common in the newborn (46.8 +/- 2.1% PT, 52.8 +/- 6.1% NT, 44.1 +/- 2.5% A males, 40.5 +/- 1.9% A females). However, this tended to be compensated for by the lower plasma viscosity (1.05 +/- 0.07 mPas PT, 1.23 +/- 0.14 mPas NT, 1.34 +/- 0.08 mPas A--no sex difference) and reduced rouleaux formation observed in the newborn and more marked in the preterm baby. The lowered levels of red cell aggregation were found not to be due to cellular differences between the adults and the babies but rather to differing plasma components. The presence of the fetal variant of fibrinogen and low levels of immunoglobulins, especially IgM and IgA, are likely to be of particular importance.

Adult↗
PubMed1989

Successful drainage of an extradural abscess in 1667: Prince Rupert's trephination.

The technique of the successful drainage of Prince Rupert's extradural abscess in 1667 has been reconstructed by putting together the details from several contemporary documents. The operation is shown to be a rational and well planned procedure in the context of the times, and not the lucky outcome of a desperate desire to try something dramatic.

Brain Abscess↗
PubMed1989

[Thromboembolic complications in pediatric orthopedics. Multicentric collection of 33 case reports].

We report 33 cases of venous thrombosis of the limb, in children aged 15 years or less (average age is 10 years old): 22 acute thrombophlebitis have been treated, 11 children shown post-phlebitic disease. The thrombus was found, most of the time, in the iliac and/or femoral vein. Acute complications were seen in 30% of our cases, and 25% treated children reviewed, had post-phlebitic sequelae. Congenital disease of hemostasis (deficiency of antithrombin III, protein C or S) must be detect before anticoagulant start, because such deficiency influence the treatment and the prognosis. There is non indication for preventive treatment, because of the rarity of spontaneous thrombophlebitis by children. Nevertheless, we can draw an "high risk" population: antecedent of phlebitis, antecedent of congenital disease of hemostasis, antecedent of thrombophlebitis by parents below 40 years old, thrombogenic disease (homocystinuria), vertebral arthrodesis.

Adolescent↗
PubMed1988

Pyruvate carboxylation in glutamine synthesis from alanine by isolated guinea-pig renal cortical tubules.

Isolated guinea-pig kidney cortex tubules were incubated in Krebs-Henseleit buffer containing NaH14CO3 (25 mM) and L-alanine (5 mM). A high rate of alanine metabolism was found to be accompanied by a high rate of both 14CO2 fixation and glutamine synthesis. The fixation of 14CO2 was virtually abolished in the presence of oxalate, a known inhibitor of pyruvate carboxylase, indicating that, in guinea-pig renal cortex, this enzyme is responsible for the synthesis of oxaloacetate in the conversion of alanine into glutamine. More than 90% of the label fixed was found in carbon 1 mainly of glutamine and to a lesser extent of glutamate. In the presence of alanine + NaH14CO3 + MSO, an inhibitor of glutamine synthetase, most of the 14CO2 fixed by pyruvate carboxylase was subsequently released and carbon 1 of glutamate was the only site of labelling. In the presence of alanine + NaH14CO3, the fact that not all the glutamine found was labelled in carbon 1 could be explained by glutamine synthesis from endogenous substrates as well as by glutamine synthesis from alanine after prior equilibration of [4-14C]-oxaloacetate with fumarate; that such equilibration occurred was demonstrated by the observation that [1-14C]-glutamine and [1-14C]-glutamate were synthesized from [1-14C]-alanine.

Alanine↗
PubMed1988

Direct effect of alpha-human atrial natriuretic peptide on human vasculature in vivo and in vitro.

1. The effect of a alpha-human atrial natriuretic peptide (1-28) (ANP) on human vasculature was investigated in vivo and in vitro. Possible involvement of vascular dopamine receptors and the renin-angiotensin system in the response to ANP was also studied in vivo. 2. Forearm blood blow was measured by venous occlusion plethysmography. Isolated human blood vessels were studied using conventional organ bath techniques. 3. ANP (0.1-1 microgram/min, intra-arterially) produced a dose-dependent increase in forearm blood flow, corresponding to a 163% increase in net forearm blood flow in the study arm. This action of ANP was not antagonized by (R)-sulpiride (100 micrograms/min, intra-arterially), a selective vascular dopamine receptor antagonist, or 50 mg of oral captopril, an inhibitor of angiotensin-converting enzyme. 4. ANP (1 nmol/l-1 mumol/l) produced concentration-dependent relaxation of isolated human arteries, including brachial artery, but was without effect on isolated human saphenous vein. 5. ANP produces vasodilatation in vivo and relaxes isolated human arterial smooth muscle. This action of ANP may contribute to its reported hypotensive effects in vivo.

Adult↗
PubMed1988

Alpha 2 adrenoceptors of blood platelets from hypertensive and normotensive rhesus monkeys.

Hypertension may cause activation of blood platelets in vivo. One of the possible mechanisms could be adrenergic activation of platelets by catecholamines. Therefore, we have studied specific binding of the alpha 2-adrenoceptor blocker, 3H-yohimbine, to platelets in order to elucidate the role of alpha 2-adrenoceptors of platelets in hypertensive animals. Particularly, competitive inhibition of 3H-yohimbine binding to platelets by hydergine, and plasma catecholamine levels were investigated in hypertensive (stress induced) and normotensive monkeys. It was demonstrated that 3H-yohimbine binds to platelets from rhesus monkeys with high affinity and specificity. The binding was found to be saturable and reversible. Additionally, it was shown that hydergine inhibits specific binding of 3H-yohimbine to platelets from hypertensive monkeys more potent that to those from normotensive animals. The obtained data suggest that the total number of the number of available, free alpha 2-adrenoceptors were reduced on the platelets from hypertensive monkeys. The latter was confirmed by the decreased adrenaline level in the plasma of hypertensive animals.

Animals↗