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Biomedical subjects

P Gerard

Publications and source records attributed to P Gerard.

At least 19 recordsLinked to original sources
PubMed1992

Facilitation of responses to motor cortex stimulation: effects of isometric voluntary contraction.

In 7 normal subjects we compared the facilitatory effect of isometric contraction of the tibialis anterior on the size of electromyographic responses evoked in this muscle by electric stimuli applied over the cervical column and by electric and magnetic percutaneous stimulation of the motor cortex. No significant difference was found between the degrees of facilitation of the responses to any of the stimuli. Using collision techniques, we also showed that the pyramidal fibers activated by spinal and cortical stimuli are the same. Facilitation induced by isometric contraction (20% maximum) was of similar or greater magnitude than that found with constant vibration of the tendon of the target muscle. In cases where vibration and contraction had equal facilitatory effects, there was no further facilitation of the responses when both conditions were applied together. These findings indicate that the facilitatory effect of isometric contraction of the target muscle essentially originates at a spinal level rather than in the motor cortex.

Adult↗
PubMed1992

High rate of multiple genital HPV infections detected by DNA hybridization.

Cervical smears collected from 450 patients involved in a clinical follow-up of cervical human papillomaviruses (HPV) infections were screened for the presence of HPV 6b, 11, 16, and 18 DNA by both dot blot and southern blot hybridization methods. Using very high stringency hybridization assays, the four HPV types could be easily distinguished by dot blotting. After a preliminary clinical sorting, 42.9% of the samples were found to be HPV-positive. Among the samples infected by a single HPV, type 16 was the most frequent (25.4% of the positive samples) followed by 6b (19.7%), 11 (8.3%), and 18 (7.2%). Double or even multiple infections by the different HPV types were detected at a very high rate (39.4% of the positive samples).

Belgium↗
PubMed1992

Neonatal seizures and severe hypotonia in a male infant suffering from a defect in peroxisomal beta-oxidation.

In this paper, we describe a baby male born to healthy non-consanguineous parents presenting at birth with hypotonia and seizures. Additional salient clinical features included the development of glaucoma, the absence of significant facial dysmorphism and the absence of liver enlargement or renal cysts. The patient died at the age of 3 months. At autopsy, liver fibrosis and kidney glomerulosclerosis were noted. Neuropathological findings included pachygyria of the olivary nuclei and cerebellar neuronal heterotopias. There was no evidence for a demyelinating process. Biochemically, the patient was found to have elevated plasma levels of very-long-chain fatty acids (VLCFA) and abnormal bile acid intermediates, whereas other indicators of peroxisomal function (plasmalogen biosynthesis and plasma pipecolic acid) were normal. Catalase staining of a liver biopsy specimen revealed peroxisomes to be present in normal numbers, although some were abnormally large. Trilamellar inclusions typical of a peroxisomal fatty acid oxidation defect were present in macrophages. Indeed, beta-oxidation of the very-long-chain fatty acid hexacosanoic acid (C26:0) was found to be strongly deficient. Fatty acyl-CoA oxidase activity in the patient's liver was normal, however. Furthermore immunocytochemical studies using antibodies against acyl-CoA oxidase, bifunctional protein and peroxisomal thiolase, revealed the normal localization of all three enzyme proteins within the peroxisomes. We suggest that our patient has a selective peroxisomal beta-oxidation defect, a recently identified heterogeneous group of early-onset peroxisomal disorders distinct from the Zellweger syndrome and other generalized peroxisomal disorders.

Acyl-CoA Oxidase↗
PubMed1991

Portal and biliary phases of enterohepatic circulation of corrinoids in humans.

The assimilation of labeled cobalamin and the transport of corrinoids in portal blood, peripheral venous blood, and bile were studied in eight cholecystectomized patients, after ingestion of a dose of cyano[57Co]cobalamin (0.5 microCi). The radioactivity appeared in the portal vein after a delay of 1.5-2 hours and in the peripheral vein 1 hour later. In bile, it reached a maximum at 24-72 hours; the excreted cobalamin corresponded to 1.42% +/- 0.92% of the dose ingested. The output of total corrinoids was 1.85 nmol/day. The high-performance liquid chromatography analysis of bile showed the presence of methylcobalamin, 5'-deoxyadenosylcobalamin, hydroxocobalamin, and an unknown corrinoid. This corrinoid bound to R binder but not to the intrinsic factor, and it had the same retention time as cobinamide. The R binder was the single cobalamin-binding protein found in bile. It was completely saturated in some periods of bile secretion. The corrinoids corresponding to such a period were eluted in Sephacryl S 300 gel filtration (Pharmacia Fine Chemicals, Uppsala, Sweden) in two peaks corresponding to saturated R binder and to free cobalamin. The mean level of total corrinoid was significantly higher in the portal vein (593 +/- 238 pmol/L) than in the peripheral vein (376 +/- 114 pmol/L) (P less than 0.01). This "cobalamin analogue" fraction was hypothetical because it was calculated from the difference between total corrinoid concentration and the so called "true cobalamin" concentration. This difference corresponded to the cobalamin analogue fraction. These data show that bile removes not only cobalamin but also cobalamin analogues and that R binder is the single carrier protein involved in their excretion.

Aged↗
PubMed1991

Cephalic and extracephalic pressure pain thresholds in chronic tension-type headache.

Pressure pain thresholds were assessed with an algometer (Somedic Inc.), over the forehead, temple and suboccipital region as well as over the Achilles tendon. A group of 32 patients suffering from chronic tension-type headache was compared to 20 healthy controls and to 10 migraineurs without aura. Although individual values were widely scattered, pressure pain thresholds were on average significantly lower in chronic tension-type headache, not only at pericranial sites but also over the Achilles tendon. Only 50% of these patients had one or more pericranial thresholds 1.5 S.D. below the mean of controls. After muscular biofeedback therapy, all pain thresholds were on average increased. Along with results obtained previously, the present data support the hypothesis that diffuse disruption of central pain-modulating systems, possibly due to a modified limbic input to the brain-stem, is pivotal in the pathophysiology of chronic tension-type headache.

Adult↗
PubMed1991

Multiple clinical and paraclinical analyses of chronic tension-type headache associated or unassociated with disorder of pericranial muscles.

Thirty-two female patients fulfilling the diagnostic criteria of chronic tension-type headache underwent multiple clinical (severity index before and after biofeedback therapy; anxiety score) and paraclinical (pericranial EMG levels and pressure-pain thresholds, temporalis exteroceptive silent period) assessments. Twenty-three patients (72%) had at least one increased EMG level and/or at least one decreased pain threshold and qualified for the subgroup" associated with disorder of pericranial muscles" (code 2.2.1). Nine patients (28%) were within the normal range for both investigations and would have been classified in the subgroup "unassociated with such disorder" (code 2.2.2). No significant differences were found between these two groups of patients for headache severity, anxiety, response to biofeedback therapy or duration of temporalis second exteroceptive silent period. The various clinical and paraclinical parameters were not significantly correlated to each other. It is therefore suggested that the subdivision of chronic tension-type headache in two subgroups based on pericranial EMG levels and/or pain sensitivity might be artificial. Since both of the latter and temporalis silent periods vary independently, they appear complementary in the study of tension-type headache patients and probably represent peripheral abnormalities, which are induced to varying intensities by a common central nervous system dysfunction.

Adolescent↗
PubMed1991

EMG activity in pericranial muscles during postural variation and mental activity in healthy volunteers and patients with chronic tension type headache.

EMG activity was recorded over frontalis, temporalis and trapezius muscles in a supine position, a standing position and during a mental task in 32 female patients suffering from chronic tension-type headache and in 20 healthy volunteers. Measurements in patients were made before and after biofeedback therapy. All EMG levels were on average significantly higher in patients than in controls. 62.5% of patients had at least one abnormal EMG level, but only 34% were beyond the normal range, if 1 muscle and 1 recording condition was considered. EMG levels were not correlated with headache severity, anxiety or response to biofeedback treatment. It is therefore suggested that pericranial EMG activity is not pathogenetic in chronic tension type headache, but merely one of several pathophysiologic changes, that are produced by a central dysfunction.

Adolescent↗
PubMed1991

[Role of neurolysis of the posterior tibial nerve in plantar perforating diseases of diabetic origin].

Perforating ulcers of the foot in diabetics constitute a difficult therapeutic problem. In a series of 17 cases, the authors stress the value of tibial nerve neurolysis associated with periarterial sympathectomy which results in cure of the 15 patients treated within 30 days. Although no electromyographic improvement was observed, perfusion studies and oxymetry demonstrated an improved local vascular situation which promoted healing.

Adult↗
PubMed1990

[125I]MIBG uptake and release in different regions of the rat brain.

Radioiodinated m-iodobenzylguanidine [( 125I]MIBG) and tritiated norepinephrine [( 3H]NE]) uptake and release were compared, in different regions of the brain of the rat. The classification of the regions according to uptake was the same for both tracers:striatum greater than hypothalamus greater than hippocampus greater than cortex greater than brainstem. Tetrabenazine (TBZ), a granular monoamine uptake inhibitor reduced the uptake in the different regions. The inhibition rate was higher for [3H]NE uptake than for [125I]MIBG. The spontaneous release was the same for [125I]MIBG and [3H]NE and was the lowest in the striatum. The K+ stimulated release of [3H]NE was more complete than the release of [125I]MIBG and was the most important in the striatum. From these results, it is inferred that MIBG enters the brain tissue via NE uptake mechanisms. It appears that MIBG is stored in the chromaffin granules, as NE, but also in the cytoplasm. A modified molecule derived from MIBG which would cross the blood-brain barrier, would then appear as a potential scintigraphic marker of monoamine uptake, storage and release.

3-Iodobenzylguanidine↗
PubMed1989

Serum unsaturated vitamin B12 proteins in adult patients with sickle cell anaemia (HbSS).

The unsaturated vitamin B12 binding capacity (UBBC) of serum, the three transcobalamins (TC I, TC II, TC III) and serum cobalamin have been studied in adult sickle cell patients with Hb SS. An increase in the level of the binding capacities of TC I and TC III resulting in an increase in UBBC was observed in these patients. There was no difference in the level of the binding capacity of TC II, while there was a significant reduction in the level of serum cobalamin. These changes in the pattern of these binding proteins are discussed in relation to the changes of these binding proteins in paediatric sickle cell patients with Hb SS. The results indicate that the pattern of these binding proteins changes with age among sickle cell patients resulting in an increased level of the binding capacities of TC I and TC III. These increases lend support to the view that these two similar binding proteins are involved in the defence mechanism of the body.

Adolescent↗
PubMed1989

[Variations of division of the extrahepatic bile ducts: significance and origin, surgical implications].

As opposed to congenital anomalies, the anatomical variations, as well as the modal type, are issued from a normal morphological development. The variations of division of extra-hepatic biliary ducts are very frequent. They are clearly explained by the sequence of embryological development in man, and also by compared anatomy. Lots of variations occur, some of them being more frequently encountered than others during cholecystectomy for gallbladder lithiasis. A cysto-hepatic duct draining a large hepatic territory is the most dangerous variation. As a matter of fact, it can look as if the junction between the cystic duct and the common biliary duct was of the modal type. In surgical practice, the dissection of cystic duct must never go over the right side of the common biliary duct in order for it never to be injured. Radiological exploration of biliary tree during cholecystectomy for gallbladder lithiasis has to be routine, in order to discover the obviously unpredictable individual variations of division of extra-hepatic biliary ducts.

Animals↗
PubMed1988

Correlation between serum enzymes and serum unsaturated vitamin B12 binding proteins in primary liver carcinoma.

The serum unsaturated vitamin B12-binding capacity (UBBC), unsaturated transcobalamin (UTC) I, UTC II, UTC III levels, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase activities and bilirubin concentration were estimated in 61 patients with liver diseases (31 with hepatoma, 30 with viral hepatitis). The levels of serum cobalamin, UTC I, UTC III, UBBC, alanine and aspartate aminotransferases, and bilirubin were raised in both hepatoma and viral hepatitis patients. Serum UTC II was reduced in both conditions. Alkaline phosphatase activity was significantly increased in hepatoma. Four significant correlations were observed among these parameters in the hepatoma patients while only one significant correlation was observed in viral hepatitis.

Adult↗
PubMed1987

Central interactions between dihydropyridines and cholinergic systems in the control of blood pressure in rat.

Intracerebroventricular (i.c.v.) injection of the 1,4-dihydropyridine (DHP) calcium channel agonist, Bay K8644 (30 micrograms/kg) increased mean blood pressure and the K+-evoked release of [3H]acetylcholine ([3H]ACh) from hippocampal slices in spontaneously hypertensive rats (SHR). The Bay K8644-induced hypertension was inhibited by a pretreatment with methylatropine (80 micrograms/kg i.c.v.). In SHR, nicardipine, a DHP calcium channel antagonist, reduced mean blood pressure when i.c.v. injected (10 micrograms/kg). The nicardipine-induced hypotension was reduced by a pretreatment with hemicholinium-3 (20 micrograms, i.c.v.). Nicardipine (1 microM) did not modify, in SHR, the K+-evoked release of [3H]ACh, but inhibited the Bay K8644-induced increase in the ACh release. In normotensive rats, neither Bay K8644 nor nicardipine modify blood pressure, when centrally injected, or the stimulated release of [3H]ACh from hippocampal slices. The participation of central DHP sites in the cholinergic transmission in genetic hypertension is discussed.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1987

Characterization of dihydropyridine binding sites in the rat brain: hypertension and age-dependent modulation of [3H](+)-PN 200-110 binding.

The properties of [3H]dihydropyridine (DHP), nitrendipine and (+)-PN 200-110, binding to rat cerebral membranes were investigated. In normotensive Wistar-Kyoto (WKY) adult rats, the highest densities of [3H]DHP binding sites were found in the hippocampus. Frontal cerebral cortex and hypothalamus had intermediate levels and no specific binding of [3H]DHP and [125I]iodipine could be detected in the brainstem membranes and more precisely in the nucleus tractus solitarius and in the locus coeruleus. Changes in the maximal number of DHP binding sites (Bmax) were observed in spontaneously hypertensive rats (SHR) and in old Sprague-Dawley rats. In adult SHR, there was a significant increase in the Bmax values of [3H](+)-PN 200-110 binding in the hippocampus when compared to the values obtained in WKY. There was no difference in the Bmax values between young (3 weeks) prehypertensive SHR and age-matched WKY. In senescent (26 months) Sprague-Dawley rats, the Bmax values of [3H](+)-PN 200-110 binding were significantly reduced (30%) in the frontal cerebral cortex and the hippocampus, as compared with the number of DHP binding sites found in mature Sprague-Dawley rats (15 weeks).

Aging↗
PubMed1986

The optical push device: an aid to the angiographer.

The frequent use of heavy eyeglasses by the angiographer has resulted in significant discomfort due to "sliding glasses." Described is the optical push device, which allows the angiographer to adjust eyeglasses comfortably while maintaining sterility.

Angiography↗