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Biomedical subjects

E Martinez

Publications and source records attributed to E Martinez.

At least 217 records · Page 12Linked to original sources
PubMed1985

Regional brain energy metabolism after complete versus incomplete ischemia in the rat in the absence of severe lactic acidosis.

Levels of energy metabolites were measured in forebrain regions in fasted rats subjected to 4-h recirculation after 1 h of either incomplete or complete ischemia. Both models of ischemia were produced by a procedure combining bilateral common carotid artery occlusion, systemic hypotension, and CSF pressure elevation; the degree of intracranial hypertension was varied to produce incomplete and complete ischemia. Levels of brain lactate at the end of ischemia ranged from 16 to 19 mmol/kg in incomplete ischemia and from 11 to 13 mmol/kg in complete ischemia. Energy metabolism recovered evenly in the neocortical and subcortical regions with recirculation after incomplete ischemia. The metabolic recovery in the cerebral cortex after complete ischemia was similar to that observed after incomplete ischemia; however, recovery in the subcortical regions after complete ischemia was less extensive, NADH fluorescence remained high, and there was a fall in total creatine. Intracellular pH in the dorsal thalamus was more alkalotic after complete than incomplete ischemia. Thus, in the absence of profound tissue lactic acidosis, residual CBF during prolonged ischemia helps postischemic restitution of brain energy metabolism in subcortical regions. The pattern of poor recovery in these regions after complete ischemia suggests inadequate reperfusion. The decreased total creatine and the severe tissue alkalosis may be biochemical markers of advanced tissue injury during reflow.

Acidosis↗
PubMed1985

[Neurogenic bladder caused by spinal cord traction].

A neurogenic bladder was the presenting syndrome in three cases of spinal cord traction. Of the typical symptomatic triad: neuro-orthopedic, cutaneous and urologic, the latter was of primary importance. Symptoms in the first case were incomplete bladder retention with distention of upper urinary tract, right-sided vesicorenal reflux and renal insufficiency. Six months after excision of a sacral lipoma and freeing of the filum terminale, micturition had become normal without residue, and renal function normalized. Right-sided reflux was corrected by submucosal advancement surgery with good results. The clinical history was more suggestive in the second case. Although inaugural symptoms were mictional, there was foot paralysis and a retrosacral lipoma above an abnormal hairy tuft in the upper part of the gluteal cleft. Operation revealed the presence of a dermoid cyst and a lipoma. Their excision combined with section of the filum terminale allowing ascension of the medullary cone. Marked clinical and urodynamic improvement was obtained with normal micturition and disappearance of incontinence. An anti-reflux operation suppressed residual reflux with good urographic results. Marked improvement in mictional disorders was obtained also in the 3rd case after excision of a sacral extradural lipoma and section of the filum terminale, allowing objective ascension of the medullary cone by 4 cm. A very detailed analysis was conducted of similar cases reported in the literature, about 2% of neurogenic bladders in children being affected. The importance of early diagnosis is emphasized as well as the essential need to establish a precise diagnosis of the lipoma of cauda equina and of medullary fixation. Early neurosurgery is justified by the high frequency of improvement in cases treated in this way.

Adolescent↗
PubMed1984

Nicergoline in the treatment of neuropathic bladder dysfunction: a preliminary report.

We have employed the alpha blocking drug Nicergoline in 14 patients with neuropathic bladder dysfunction of the upper motor neurone type. The oral administration of 15-30 mgrs/day of this drug over a period of 9.5 months significantly improved the urodynamic parameters, with an increase of bladder capacity, a disappearance or amelioration of uninhibited bladder contractions and a decrease in urethral pressure, profile urethral length and residual urine. Two patients with vesico-ureteral reflux present before treatment showed radiological improvement after Nicergoline administration. Tolerance of Nicergoline had been excellent without appreciable side effects. In conclusion, Nicergoline seems to be active and well tolerated in the pharmacological treatment of neuropathic bladder dysfunction.

Adolescent↗
PubMed1984

Free fatty acids and energy metabolites in ischemic cerebral cortex with noradrenaline depletion.

We tested whether cerebral noradrenaline (NA) may play a central role in mediating the increased production of free fatty acids (FFAs) during cerebral ischemia. Levels of FFAs, cyclic AMP, and NA, as well as ATP, ADP, and AMP, were measured in cerebral cortex during decapitation ischemia in rats 2 weeks after unilateral locus ceruleus lesion. Comparisons were made between the results obtained from the contralateral cortex with normal NA content and the NA-depleted ipsilateral cortex. Although NA depletion was associated with a diminished transient rise of cyclic AMP in response to ischemia, it failed to influence the magnitude of FFA increase or the decline of energy state within the 15-min period of ischemia. A more than twofold increase of total FFAs (sum of palmitic, stearic, oleic, arachidonic, and docosahexaenoic acids) was observed in both hemispheres at 1 min after decapitation, when energy failure became manifest. The increased production of FFAs continued throughout the 15 min of ischemia, with a preferential rise in the levels of stearic and arachidonic acids. There was an inverse correlation between FFA levels and total adenylate pool. The results do not support a major role for NA and cyclic AMP in increasing cortical FFAs during complete ischemia. Instead, they are consistent with the view that impaired oxidative phosphorylation activates deacylating enzymes. Disturbance of reacylation due to energy depletion is probably another factor contributing to the continuous increase of FFAs during prolonged ischemia.

Adenine Nucleotides↗
PubMed1983

Altered nicotinic sensitivity of AV node in surgically denervated canine hearts.

The responses of normal and cardiac-denervated (DNV) dogs to acetylcholine (ACh) and nicotine (NIC) were examined to determine if the intrinsic cardiac nerves (ICN) that modulate electrical conduction display denervation supersensitivity. Control (n = 18) and DNV (n = 18) animals were placed on cardiopulmonary bypass. Recording of intra-atrial (P-A), intraventricular (H-V), and atrioventricular (AV) nodal (A-H) conduction times were made from the region of the His bundle. ACh (0.1-10 micrograms) was used to produce muscarinic stimulation, whereas NIC (0.1-400 micrograms) was employed to stimulate the ICN. All drugs were administered intracoronary. No supersensitivity to either ACh or NIC was seen in the data from the P-A or H-V intervals of the His electrogram in the DNV animals. However, this group displayed approximately a 10-fold increase in the negative dromotropic effect of NIC on the AV node compared with control. No significant change in muscarinic sensitivity of the AV node was observed in the DNV animals. We conclude that 1) no denervation supersensitivity of the ICN mediating effects on intra-atrial and intraventricular conduction occurs; 2) the AV node itself does not show muscarinic supersensitivity following extrinsic denervation; 3) the ICN do display denervation supersensitivity as shown by a 10-fold increase in the effects of NIC on AV nodal conduction time.

Acetylcholine↗
PubMed1983

Effect of prostaglandins E1, E2, and F2 alpha on the electric activity of the sphincter of Oddi in living rabbit.

The effect of prostaglandins (PGs), i.e. PGE1, PGE2 and PGF2 alpha (0.5-32 micrograms/kg), on the electrical activity of the rabbit sphincter of Oddi was studied in vivo. PGs were injected intravenously as a bolus and electrical activity of the sphincter and the duodenum was recorded before and during 15 min after the injection. Variations in biliary pressure were also studied at the same time. PGE1 strongly decreased the activity of the sphincter and biliary pressure which were both increased by PGF2 alpha. Both PGE1 and PGF2 alpha showed a dose-response curve of Michaelis-Menten type. Unexpectedly PGE2 increased at first then decreased electrical activity but not significantly. These effects appeared very early after intravenous injection and were evident with low doses.

Action Potentials↗
PubMed1983

Compression-induced brain edema: modification by prior depletion and supplementation of vitamin E.

We studied the degree of edema resulting from focal brain compression in rats raised on vitamin E-deficient, -normal, or -supplemented diets. After release of 24 hours of epidural compression, edema developed ipsilaterally and was characterized by extravasation of serum protein, increased water and sodium content, and little change in potassium. The degree of swelling and increase of sodium in the previously compressed area were most pronounced in the vitamin E-deficient group and mildest in the vitamin E-supplemented group. Degradative processes of biomembranes seem to participate in the pathogenesis of brain edema; vitamin E may stabilize membranes by physicochemical interactions between the phytyl side chain and polyunsaturated phospholipids, or vitamin E may disrupt chains of free radical reactions.

Animals↗
PubMed1983

Tonic-phasic-channel dichotomy and Crozier's law.

The constancy of the dynamic range in a luminance-discrimination task is known as Crozier's law; an old rule says that about half of a log unit spans the range from a low to a high frequency of seeing. For our conditions the slope of the psychometric function is steeper for short than for long test flashes; Crozier's law requires a different constant when temporal parameters change. This result is substantiated by an analysis of Massof's data [Vision Res. 21,995 (1981)] on the variation of the slope of psychometric curves for different wavelengths. The change in Crozier's constant between conditions may reflect the presence of more than one detection channel. If short test flashes are detected by phasic channels and long test flashes by both phasic and tonic channels, then our result implies a shorter dynamic range for phasic (Y-cell) than for tonic (X-cell) channels.

Computers↗
PubMed1982

Human proliferative sparganosis in Venezuela: report of a case.

A case of human proliferative sparganosis, the first in the southern hemisphere, is reported. The patient had multiple nodular, papular, acne-like lesions, gynecomastia, and large subcutaneous abscesses. Laboratory findings showed that he also had severe anemia of the type associated with infection and chronic diseases, leukocytosis, eosinophilia, and severe hypoalbuminemia and hypergammaglobulinemia. His cellular and humoral immune responses were unaltered. New aspects on the functional repercussion of the parasitism of the human host by Sparganum proliferum are discussed. Treatment with mebendazole was ineffective; the patient's tolerance for the newer drug praziquantel was extremely poor.

Adult↗
PubMed1982

Norepinephrine regulation of cerebral glycogen utilization during seizures and ischemia.

Norepinephrine (NE) depletion of the cerebral cortex after lesion of the ipsilateral locus ceruleus (LC) causes abnormalities of cerebral oxidative metabolism when the cortex is stimulated to increased energy demand (Harik, S. I., J. C. LaManna, A. I. Light, and M. Rosenthal (1979) Science 206: 69-71; LaManna, J. C., S. I. Harik, A. I. Light, and M. Rosenthal (1981) Brain Res. 204: 87-101). These abnormalities were exhibited as decreased mitochondrial reducing equivalent flow. One possible cause of this would be the decreased availability of oxidative metabolic substrates in the NE-depleted cortex. We therefore investigated the effect of unilateral LC lesion and the resultant depletion of ipsilateral endogenous NE on glycogen and other energy metabolites in the cerebral cortex of rats under three conditions: (1) at "rest," (2) when energy demand is inncreased markedly by seizures, and (3) during total cerebral ischemia. We report no differences in cerebral metabolites between NE-depleted and control hemispheres at "rest." In seizures and ischemia, however, the increase in the level of adenosine 3':5'-monophosphate (cyclic AMP) and the breakdown of glycogen were impaired considerably in the NE-depleted cortex. The data suggest that depletion of central NE impairs cerebral glycogenolysis in response to increased energy demands and ischemia. Such impairment may be mediated via a cyclic AMP-related mechanism.

Animals↗