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Biomedical subjects

J Lamarche

Publications and source records attributed to J Lamarche.

At least 19 recordsLinked to original sources
PubMed2003

Management of fetal tachyarrhythmia based on superior vena cava/aorta Doppler flow recordings.

OBJECTIVE: To evaluate a management protocol of fetal supraventricular tachycardia (SVT) based on prior identification of the underlying mechanism. DESIGN AND SETTING: Prospective study in a mother-child tertiary university centre. PATIENTS: During a consecutive 36 month period, 18 fetuses with sustained SVT underwent a superior vena cava/ascending aorta (SVC/AA) Doppler investigation in an attempt to determine the atrioventricular (AV) relation and to treat the arrhythmia according to a pre-established management protocol. MAIN OUTCOME MEASURE: Rate of conversion to sinus rhythm. RESULTS: Seven fetuses had short ventriculoatrial tachycardia, five of these with a 1:1 AV conduction suggesting re-entrant tachycardia. The first choice drug was digoxin and all were converted. One fetus had AV dissociation leading to the diagnosis of junctional ectopic tachycardia, which was resistant to digoxin and sotalol; amiodarone achieved postnatal conversion. One fetus had SVT and first or second AV block; the diagnosis was atrial ectopic tachycardia (AET), which responded to sotalol given as a drug of first choice. Seven fetuses had long ventriculoatrial tachycardia: one with sinus tachycardia (no treatment), one with permanent junctional reciprocating tachycardia (PJRT), and three with AET. The first choice drug was sotalol and all were converted. One AET was classified postnatally as PJRT. Six fetuses had intra-atrial re-entrant tachycardia: five with 2:1 AV conduction and one with variable block. The first choice drug was digoxin. Conversion was achieved in all but one, who died after birth from advanced cardiomyopathy. CONCLUSION: The electrophysiological mechanisms of fetal SVT can be clarified with SVC/AA Doppler. The proposed management protocol has so far yielded a good rate of conversion to sinus rhythm.

Anti-Arrhythmia Agents↗
PubMed2001

Ethanol delays and reverses lysophosphatidylcholine-induced calcium overload in neonatal rat heart cells.

Increased lysophosphatidylcholine (LPC) production by the ischemic heart is associated with tissue damage. In vitro, LPC produces an increase in cytosolic [Ca2+], usually followed by cell contracture and lysis. Since ethanol reportedly protect cells during ischemia-reperfusion, we wished to determine whether ethanol could protect heart cells against LPC-induced Ca2+ overload. Newborn rat heart cells in culture were loaded with Fura-2 and [Ca2+]i recorded in individual cells. The presence of 22 or 44 mM ethanol increased the time required for 10 microM x L-palmitoyl-LPC to produce maximal Ca2+ accumulation from 8.4+/-0.4 min (n=47) to 21.1+/-2.1 x min (n=32; P<0.01) and 23.8+/-1.8 min (n=10; P<0.01) respectively. The onset of the [Ca2+]i increase could be reversed partially by the addition of ethanol (44 or 88 mM). After the addition of 22 mM ethanol, the cells retained the Fura-2 three times longer than under control conditions. Ethanol (88 mM) decreased the critical micelle concentration of LPC, thus decreasing the LPC monomer concentration in this solution. La3+ also protected the cells against LPC but no further protection was afforded by the addition of ethanol. Our results suggest that ethanol concentrations commonly found in the blood of social drinkers protect heart cells against the deleterious effect of LPC.

Animals↗
PubMed2000

Abnormal activity of membrane phospholipid synthetic enzymes in the brain of patients with Friedreich's ataxia and spinocerebellar atrophy type-1.

Much evidence, derived from biochemical studies of both blood and autopsied brain, has suggested that phospholipid metabolism is abnormal in patients with Friedreich's ataxia (FA), a disorder characterized by severe neuronal loss in the spinal cord and lower brain stem with no, or only modest, damage in other brain regions. To establish the cause of our recent finding of reduced brain levels of phospholipids in FA, we assayed activities of 10 phospholipid-metabolizing enzymes in the autopsied cerebellar cortex of patients with the disorder and, for comparison, in a group of patients with spinocerebellar ataxia type 1 (SCA-1), a disease characterized, unlike FA, by marked neuronal loss in the cerebellar cortex. Enzyme activities were also measured in four brain areas which are relatively unaffected morphologically in both FA and SCA-1. We found that ethanolamine kinase activity was increased in multiple brain regions of patients with FA (increased 31%-137%) and, more modestly, in SCA-1 (increased 39%-60%), suggesting a nonspecific enhancement of phosphoethanolamine production in both disorders. In contrast, the activity of phosphoethanolamine cytidylyltransferase (PECT), the rate-limiting enzyme of phosphatidylethanolamine synthesis, was significantly and markedly decreased by 35%-78% in the cerebellar, frontal, and occipital cortices of patients with FA but was normal in SCA-1. Reduced PECT activity in FA may explain the lower brain levels of phosphatidylethanolamine in the disorder. Moreover, because decreased PECT activity in FA occurs in brain regions having no, or only modest, morphologic damage, this may represent a systemic change consequent to the frataxin gene defect. Our data also suggest that therapeutic intervention in FA designed to increase synthesis of membrane phospholipids may warrant further investigation.

Adult↗
PubMed1999

From genotype to phenotype: a clinical pathological, and biochemical investigation of frontotemporal dementia and parkinsonism (FTDP-17) caused by the P301L tau mutation.

Frontotemporal dementia is a heterogeneous, often inherited disorder that typically presents with the insidious onset of behavioral and personality changes. Two genetic loci have been identified and mutations in tau have been causally implicated in a subset of families linked to one of these loci on chromosome 17q21-22. In this study, linkage analysis was performed in a large pedigree, the MN family, suggesting chromosome 17q21-22 linkage. Mutational analysis of the tau coding region identified a C-to-T change in exon 10 that resulted in the conversion of proline to a leucine (P301L) that segregated with frontotemporal dementia in this family. The clinical and pathological findings in the MN family emphasize the significant overlap between Pick's disease, corticobasal degeneration, and frontotemporal dementia and challenge some of the current dogma surrounding this condition. Pathological studies of two brains from affected members of Family MN obtained at autopsy demonstrate numerous tau-positive inclusions that were most prominent in the frontal lobes, anterior temporal lobes, and brainstem structures, as well as Pick-like bodies and associated granulovacuolar degeneration. These Pick-like bodies were observed in 1 patient with motor neuron disease. Because exon 10 is present only in tau mRNA coding for a protein with four microtubule binding repeats (4R), this mutation should selectively affect 4Rtau isoforms. Indeed, immunoblotting demonstrated that insoluble 4Rtau is selectively aggregated in both gray and white matter of affected individuals. Although there was significant pathological similarity between the 2 cases, the pattern of degenerative changes and tau-positive inclusions was not identical, suggesting that other genetic or epigenetic factors can significantly modify the regional topology of neurodegeneration in this condition.

Brain↗
PubMed1999

Decreased brain protein levels of cytochrome oxidase subunits in Alzheimer's disease and in hereditary spinocerebellar ataxia disorders: a nonspecific change?

Controversy exists as to the clinical importance, cause, and disease specificity of the cytochrome oxidase (CO) activity reduction observed in some patients with Alzheimer's disease (AD). Although it is assumed that the enzyme is present in normal amount in AD, no direct measurements of specific CO protein subunits have been conducted. We measured protein levels of CO subunits encoded by mitochondrial (COX I, COX II) and nuclear (COX IV, COX VIc) DNA in autopsied brain of patients with AD whom we previously reported had decreased cerebral cortical CO activity. To assess disease specificity, groups of patients with spinocerebellar ataxia type I and Friedreich's ataxia were also included. As compared with the controls, mean protein concentrations of all four CO subunits were significantly decreased (-19 to -47%) in temporal and parietal cortices in the AD group but were not significantly reduced (-12 to -17%) in occipital cortex. The magnitude of the reduction in protein levels of the CO subunits encoded by mitochondrial DNA (-42 to -47%) generally exceeded that encoded by nuclear DNA (-19 to -43%). In the spinocerebellar ataxia disorders, COX I and COX II levels were significantly decreased in cerebellar cortex (-22 to -32%) but were normal or close to normal in cerebral cortex, an area relatively unaffected by neurodegeneration. We conclude that protein levels of mitochondrial- and nuclear-encoded CO subunits are moderately reduced in degenerating but not in relatively spared brain areas in AD and that the decrease is not specific to this disorder. The simplest explanation for our findings is that CO is decreased in human brain disorders as a secondary event in brain areas having reduced neuronal activity or neuronal/synaptic elements consequent to the primary neurodegenerative process.

Aged↗
PubMed1995

[Significance of polyglucosan bodies in neuropathology. Clinico-pathologic study of seven cases].

Seven observations, having in common an accumulation of polyglucosan bodies in the nervous system, are reported. In 2 cases of adult polyglucosan body disease, characteristic polyglucosan bodies were found on the peripheral nerve biopsies, and also on the cerebral biopsy in one of these patients who was demented. The 5 other cases presented medically intractable temporal lobe epilepsy. Recovery was obtained by a temporal lobectomy in which a massive accumulation of polyglucosan bodies was discovered. These personal observations are discussed with regard to other conditions characterized by accumulation of polyglucosan bodies in the nervous system. The non specificity of these formations is emphasized.

Adult↗
PubMed1988

Experimental allergic encephalomyelitis: a neurourological study.

To assess the neurourological disturbances produced by the perivascular inflammatory process in the acute phase of experimental allergic encephalomyelitis, we carried out a controlled study. Forty-six New Zealand male rabbits were inoculated with an encephalitogenic preparation. Twenty-seven of them developed neurological deficits in an average of 9.3 days postinoculation. A sample of 19 subjects was used as a control. The subjects were studied within 2 days after the manifestation of the first sign of encephalomyelitis. An average of eight successive cystosphincterograms were recorded. Their entire central nervous system was removed intact and suspended in 10% neutral buffered Formalin solution for 2 weeks, then cut into segments, embedded in paraffin, and finally stained with hematoxylin-eosin and Luxol Fast Blue. The results demonstrated a significant reduction of mean vesical capacity, maximum urethral pressure, and mean urethral pressure in the group with encephalomyelitis. Furthermore, we found a significant negative correlation between the average number of cellular perivascular infiltrates in the spinal sacral segment and urethral pressures. The results showed a significant negative correlation between supreamesencephalic inflammation and mean vesical capacity.

Animals↗
PubMed1988

Colonic hamartomas in tuberous sclerosis.

Twelve patients, 5 from the same family, diagnosed consecutively to suffer from tuberous sclerosis were investigated for gastrointestinal polyps. Six patients had no clinical neurologic involvement. Nine had colonic polyps: in 5 patients, these were hamartomas, in 3 patients adenomatous polyps, and the ninth patient had hamartomas and adenomatous and villoglandular polyps. Hamartomatous polyps were identical to those found in the Peutz-Jeghers syndrome. However, in 1 patient they included neural structures and in another there were angiomatous and adipous structures in addition to colitis cystica profunda. Two patients with hamartomatous polyps had normal intelligence and no clinical neurologic symptoms. The evaluation of one kindred revealed the association of hamartomatous polyps of the colon with forme fruste of tuberous sclerosis in different members, but none had the typical disease. Tuberous sclerosis should thus be considered in the differential diagnosis of hamartomatous colonic polyps. Conversely, colonic endoscopy may be a useful adjunctive test in the diagnosis of tuberous sclerosis, particularly in the incomplete varieties of disease.

Adolescent↗
PubMed1987

Pattern electroretinogram and optic nerve section in pigeons.

We studied the effect of optic nerve section on the pattern electroretinogram (PERG) of 10 pigeons. Base line PERG and flash ERG were measured prior to surgery and then one optic nerve was cut. We measured PERG at various time intervals up to 24 weeks after the section. There was a sharp drop in PERG amplitude immediately following the section. It gradually returned to normal levels in the following 24 weeks. Significant decreases in time to peak were noted at 1 and 16 weeks for 0.5 cycle per degree checks and at 1, 2 and 9 weeks for 0.25 cycle per degree checks. The ERG generated by a TV stimulus did not change in amplitude but had a shorter time to peak at 24 weeks for a high intensity stimulus and at 16, 18, 24 weeks for a low intensity stimulus. Light and electron microscopic sections (at 24 weeks) revealed an almost complete loss of nerve fibers in the optic nerve. Retinal sections revealed only a few surviving ganglion cells and a few nerve fibers. This suggests that in pigeons, PERG is not generated by ganglion cells.

Animals↗
PubMed1987

Carcinomatous neuropathy. An ultrastructural study of ten cases.

Superficial peroneal nerve biopsies were studied from 10 patients with carcinomatous neuropathy. There were 6 patients with the sensorimotor form and 4 patients with the sensory form. In both forms of neuropathy, histometric studies showed a variable loss of myelinated fibers which was generally most severe in the sensory form. In most of the cases of the sensorimotor form, ultrastructural studies showed segmental demyelination with onion bulb formation and regeneration of myelinated fibers. In the sensory form, there was no segmental demyelination, the regeneration of myelinated fibers was minimal and all the cases showed a loss of unmyelinated fibers. In sensory neuropathy, the histometric and ultrastructural changes reflect the massive acute destruction of ganglion cells in the dorsal root ganglia. In sensorimotor neuropathy, the alterations indicate a slowly progressive degenerating process in which both axonal degeneration and segmental demyelination occurred.

Aged↗
PubMed1985

The ventilatory response to hypoxia in the newborn lamb after carotid body denervation.

Neonates of various species including lambs respond to hypoxia by a transient hyperventilation followed by a VE depression (diphasic response). To better delineate the role of the carotid chemoreceptors and that of the central depressive/inhibitive effect of hypoxia on minute ventilation, we have studied the VE response of 4-day-old carotid body-deprived lambs (CBD) during successive exposure to moderate and severe (0.12 and 0.07 FIO2) hypoxia. The carotid body denervation was done to abolish most of the chemoreceptor stimulating effect on VE during hypoxia and to allow for central depression/inhibition of VE during hypoxia. In the CBD lambs, baseline VE was 461 +/- 81 (SE) ml X (kg X min)-1. It increased to 532 +/- 79 ml X (kg X min)-1 and to 541 +/- 75 ml X (kg X min)-1, to 0.12 FIO2 and 0.07 FIO2. These VE increases did not reach level of significance (P greater than 0.05). After 2-5 min of both levels of hypoxia VE dropped respectively to 460 +/- 60 ml X (kg X min)-1 and to 459 +/- 38 ml X (kg X min)-1. No marked ventilatory depressions were noted but VE had only returned to baseline. It is concluded that, in the denervated newborn lamb, the centrally mediated depressive effect of hypoxia is small and not sufficient to explain the diphasic VE response of the intact lamb to steady state hypoxia. Analysis of the magnitude of the hyperventilation and the VE damping pre-hypoxic levels occurring with sustained hypoxia in newborns of various species suggests that the immaturity of the O2-sensitive chemoreceptor rather than the central effect of hypoxia is the determinant factor of the diphasic response of newborn mammals to hypoxic hypoxia.

Animals↗
PubMed1985

Postnatal maturation of respiration in intact and carotid body-chemodenervated lambs.

The contribution of the carotid body chemoreceptor to postnatal maturation of breathing was evaluated in lambs from 7 to 70 days of age. The study was conducted by comparing the eupneic ventilation and resting pneumograms in intact conscious lambs with those of lambs that were carotid body chemodenervated (CBD) at birth. In comparison to the 1-wk-old intact lambs, the CBD lambs had significant decreases in minute ventilation (VE, 313 vs. 517 ml/kg), tidal volume (VT, 7.2 vs. 10.5 ml/kg), respiratory rate (f, 44 vs. 51 breaths/min), and occlusion pressure (P0.1, 2.8 vs. 7.2 cmH2O). Arterial PO2's were 59 vs. 75 Torr (P less than 0.05) and arterial PCO2's 47 vs. 36 Torr (P less than 0.05), respectively, in CBD and intact lambs. In intact lambs from 7 to 70 days, resting VE decreased progressively from 517 to 274 ml/kg (P less than 0.01) due to a fall in VT, mean inspiratory flow (VT/TI), and f, whereas the ratio of inspiratory time to total breath duration remained constant. P0.1 decreased from 7.2 to 3.9 cmH2O from 7 to 42 days. In contrast the CBD lambs experienced only minimal changes in VE, VT, VT/TI, and f during the same period. VE only decreased from 313 to 218 and P0.1 from 2.8 to 2.4 cmH2O. In contrast to that of intact lambs the resting pneumogram of CBD lambs remained relatively fixed from 7 to 70 days. Three CBD lambs died unexpectedly, without apparent cause, in the 4th and 5th wk of life.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Sympathetic uveitis 66 years after injury.

We report a case of sympathetic uveitis occurring 66 years after perforating trauma to the other eye. To our knowledge this is the longest interval ever cited in the literature.

Aged↗
PubMed1983

Necrosis as a prognostic criterion in malignant supratentorial, astrocytic gliomas.

Surgical specimens of malignant, supratentorial, astrocytic gliomas from 503 patients randomized on an RTOG-ECOG treatment protocol were examined by central pathologic review. The diagnosis of glioblastoma multiforme (GBM) was made only when one or more foci of coagulation necrosis involving astrocytic tumor cells were identified histologically. Malignant astrocytic neoplasms without necrosis were classified as astrocytoma with atypical or anaplastic features (AAF). The median survival stratifying for treatment for patients with GBM was eight months compared to 28 months for patients with AAF. In most cases the specimens were received with a Kernohan grade. On the basis of these grades, patients with astrocytoma Grade 3 had a median survival of ten months as compared to a median survival of nine months for those with astrocytoma Grade 4. Observations demonstrate that necrosis is a reliable, decisive prognostic factor associated with malignant, supratentorial, astrocytic gliomas. The Kernohan system is of limited value in assessing prognosis for this group of tumors.

Aged↗
PubMed1983

Constipation with colonic inertia. A manifestation of systemic disease?

Transit of radiopaque markers was delayed in the ascending colon of 51 females and 3 males treated for severe idiopathic constipation. Onset of symptoms was between age 10 and 20 in more than half of the patients. Eighteen percent had previously undergone unnecessary laparotomy for large bowel pseudoobstruction. Stool frequency ranged from 1 stool every three days to 1 every 2 months. Twenty-six percent suffered from fecal incontinence. In addition, 30% had orthostatic hypotension and 15% galactorrhea of idiopathic origin. Patients had a higher than normal anal pressure (P less than 0.001). They all had a rectoanal inhibitory reflex, but it was abnormal in 76%. In the upper esophageal sphincter, resting pressure was higher (P less than 0.02), and coordination poorer (P less than 0.05) than in normal control subjects. Incidence of spontaneous tertiary contractions in the body of the esophagus was greater than normal (P less than 0.03). In the lower esophageal sphincter, resting pressure was lower (P = 0.001) and gastroesophageal gradient weaker (P = 0.05). Closing pressure of the sphincter was lower (P less than 0.001) and coordination less adequate (P less than 0.02). After subcutaneous injection of 0.035 mg/kg bethanechol, urinary bladder intraluminal pressure increased by over 15 cm H2O in 31% of patients but never did in controls, and average maximal pressure was greater (P less than 0.025). Time taken to reach peak pressure was shorter (P less than 0.01). This study provides evidence that patients who suffer from constipation with colonic inertia also have abnormal function in other hollow viscera.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗