Biomedical subjects

J Lavoie

Publications and source records attributed to J Lavoie.

At least 55 records · Page 3Linked to original sources

PubMed1989

Changes in lectin binding of lumbar dorsal root ganglia neurons and peripheral axons after sciatic and spinal nerve injury in the rat.

The effects of chronic lesions of rat lumbar spinal or sciatic nerves on the binding of Glycine max (soybean) agglutinin to galacto-conjugates, in small- and medium-size primary sensory neurons of the L4 and L5 dorsal root ganglia, were examined over a 580-day period. Spinal nerve section resulted in a marked decrease in the population of stained neurons within 7 days. However, despite some retrograde morphological changes triggered by axonal injury, the proportion of stained nerve cells was normalized 180 days postoperatively. This temporary decrease in perikaryal lectin reactivity was initially associated with a marked accumulation of stained material in the nerve, proximal and distal to the site of section, with similar accumulations also being noticeable at each level of injury in sciatic nerves subjected to double ligature. This may reflect the presence of glycocompounds linked to the autolysis of nerve fibers during the phase of retrograde dying-back and Wallerian degeneration. At later stages, stained deposits could be seen scattered along central and peripheral axonal processes of the dorsal root ganglion neurons in the vicinity of the cell body. They may indicate a disturbance in the peripheral turnover of glycoproteins in chronically-transected nerves, with piling up of neuronal products. Sciatic nerve injury caused similar but less severe effects which, except for the L4 ganglion cells, were rapidly reversible.

Animals↗

PubMed1988

A comparative study of the effects of chronic axotomy, crush lesion and re-anastomosis of the rat sural nerve on horseradish peroxidase labelling of primary sensory neurons.

Chronic axotomy is detrimental to the incorporation of horseradish peroxidase (HRP) by neurons of the central and peripheral nervous system. Using the rat sural nerve as a model, this study aimed to determine the effects of other types of nerve injury on the peroxidase labelling of dorsal root ganglion (DRG) cells. Compared to the decreased labelling occurring shortly after permanent transection of the sural axons at the ankle, crush injury of the nerve had no effect on the number and size distribution of peroxidase-stained cells. Re-anastomosing the sural nerve to its own distal segment or to the tibial nerve delayed the changes in HRP neuronal labelling, which subsequently were less severe in neurons allowed to reinnervate their own nerve. It also sustained the incorporation of HRP by many large DRG neurons, a function which is lost shortly after these cells are chronically axotomized. Nerve re-anastomosis also prevented the retrograde atrophy of myelinated and unmyelinated nerve fibers which is triggered by permanent transection. Based on the preservation of fiber counts in the sural nerves proximal to the site of surgery, with no evidence of degeneration, our observations possibly reflect alterations in the peroxidase metabolism of DRG neurons depending on the type of axonal injury they sustained and the possibility they had upon regeneration to contact endoneurial tubes and ultimately their original end-organs.

Animals↗

PubMed1988

Spontaneous abortion in women employed in plastics manufacture.

An analysis was made of 193 current and previous pregnancies of women employed at time of conception in the plastics industry, derived from a survey of work and pregnancy in 56,012 women in Montreal, 1982-84. The ratio of observed to expected spontaneous abortions, corrected by logistic regression for seven nonoccupational confounding variables, was elevated (1.27), but not significantly (90% confidence interval [CI] 0.91-1.72), in women engaged in process work. The ratio was significantly raised (1.58, 90% CI 1.02-2.35) in women whose work included the processing of polystyrene. Nonsignificant excesses in women working with polyolefine (1.30) and polyvinyl (1.39) were present only when exposure also included other types of plastic; no excess was observed in women whose work did not include polystyrene. The number of women (17) exposed to polyurethane was too small for any conclusion to be drawn about this group.

Abortion, Spontaneous↗

PubMed1988

Histochemical localization of carbonic anhydrase in normal and diseased human muscle.

A method is described for histological localization of carbonic anhydrase (CA) in sections of frozen human muscle using the rapid and inexpensive histochemical technique of Hansson. Results obtained in normal subjects indicate clearly that CA reactive fibers are of type 1. Similarly, abnormalities seen with CA in the muscle biopsy of a patient presenting with type 1 fiber hypotrophy and preponderance duplicated almost exactly those observed with the actinomyosine adenosine triphosphatase and the reduced nicotinamide adenine dinucleotide dehydrogenase reactions. Observations of grouped CA-positive muscle fibers in a case of chronic neurogenic atrophy suggest that, like other enzymes, CA expression in muscle is under neurogenic control.

Adenosine Triphosphatases↗

PubMed1988

Differential effects of distal and proximal nerve lesions on carbonic anhydrase activity in rat primary sensory neurons, ventral and dorsal root axons.

The effect of proximal and distal peripheral nerve injuries on the histochemistry of carbonic anhydrase (CA) in rat dorsal root ganglion (DRG) neurons, and myelinated (MyF) dorsal and ventral root fibers was studied. Sciatic neurectomy induced no change. Contrariwise, 7 days after lumbar spinal nerve section the numbers of CA-stained ventral root MyF and DRG cells at the L4 and L5 levels decreased to 73.2% and 51.9% of their original values respectively, although the numbers returned to normal by the 90th postoperative day. Dorsal root MyF followed a similar trend, albeit with some delay. Major morphological changes comprised atrophy of dorsal root sensory neurons and axons, particularly in long term experiments, as well as nuclear eccentricity in DRG neurons. These results suggest that, depending on the site of lesion, the rat peripheral nervous system (PNS) either maintains or quickly restores its capacity to synthesize CA. They stand in contrast to the long-lasting metabolic dysfunctions reported to occur when primary neurons are disconnected from the periphery. It is uncertain whether this difference is due to the critical role of CA in neuronal metabolism.

Animals↗

PubMed1988

Carbonic anhydrase and horseradish peroxidase: double labelling of rat dorsal root ganglion neurons innervating motor and sensory peripheral nerves.

Dorsal root ganglion neurons supplying peroneus longus, soleus and gastrocnemius medius muscles and the sural nerve of the rat were labelled with horseradish peroxidase and analysed for their carbonic anhydrase content. Staining of the sections was done either on the same or on alternate slides. Both methods led to the same results, despite a slight fading of the carbonic anhydrase reaction in double-stained sections. The data indicated that the muscles under study were supplied by approximately the same number of horseradish peroxidase-labelled cells, irrespective of their differences in size. 74.9% of these labelled neurons had diameters exceeding 30 microns and 52.4% of them also stained for carbonic anhydrase. The double-labelled cells represented 66.9% of the population of large neurons (greater than 30 microns) and comprised most of those measuring over 47.5 microns. Richness in carbonic anhydrase of the large muscle afferent neurons may be linked to their innervation of the stretch receptors, as components of an active apparatus which includes the gamma motor axons which also stain positively for carbonic anhydrase. In contrast, the ganglion cells supplying the sural nerve were almost totally devoid of carbonic anhydrase, as only 6.4% showed double labelling. This contingent possibly represents the muscle afferents of the small motoneural population which supplies, through this nerve, part of the foot musculature of the rat.

Acid-Base Equilibrium↗

PubMed1988

Fetal death and work in pregnancy.

The relation between spontaneous abortion (n = 5010), stillbirth without congenital defect (n = 210), and working conditions was analysed in 22,613 previous pregnancies of 56,067 women interviewed, 1982-4, immediately after termination of their most recent (current) pregnancy. The 22,613 previous pregnancies were those in which at time of conception the women were employed 30 or more hours a week. Ratios of observed (O) to expected (E) fetal deaths after allowance by logistic regression for seven non-occupational confounding variables were calculated at four stages of pregnancy in 60 occupational groups and six main sectors for women whose work entailed various physical demands, environmental conditions, and exposure to chemicals. The O/E ratios for abortion were raised in the sales sector (1.13, p less than 0.05) and services sector (1.11, p less than 0.01) and for stillbirth in the sales sector (1.50, p less than 0.1). Substantially increased O/E ratios for late but not early abortion were found in operating room nurses (2.92, p less than 0.05), radiology technicians (3.82, p less than 0.01), and employees in agriculture and horticulture (2.40, p less than 0.05); in all categories the O/E ratio for stillbirth were also raised but only significantly (5.55, p less than 0.01) in the latter group. The O/E ratio for stillbirth was also raised in leather manufacture (3.09, p less than 0.01). In both individual and grouped analysis (the latter undertaken to minimise the possible effect of recall bias) significantly increased O/E ratios for abortion were found in women exposed to various high levels of physical stress, particularly weight lifting, other physical effort, and standing (p less than 0.01). Increased ratios for stillbirth at this level of significance (p less than 0.01) were found for other physical effort and vibration. Noteworthy chemical exposure was identified only in the health, services, and manufacturing sectors; the O/E ratio for stillbirth approached two in women exposed to solvents, almost all in manufacturing (p less than 0.01). In the latter sector exposed to solvents was also associated with an approximately 20% increase in abortion ratio at similar probability level.

Abortion, Spontaneous↗

PubMed1988

Congenital defects and work in pregnancy.

The risk of congenital defect was examined in 47,913 pregnancies of women employed for 15 hours a week or more at time of conception. The rate of defects of all types per 1000 births in this series was 25.0; 1.8 from defects classified as chromosomal (group A), 10.8 as developmental (group B), and 12.5 as musculoskeletal (group C). Some evidence of an excess in the risk ratio (p less than 0.05) was found in the services sector and in four occupations--agriculture and horticulture (2.61), telephone and postal clerks (1.74), a miscellaneous group of service jobs (1.68), and receptionists and information clerks (1.47); excesses of lower statistical significance (p less than 0.1) were found in those engaged in plastics and rubber manufacture (2.02) and in child minders (1.84). There were two cases of tracheo-oesophageal fistula--a rare defect--among eight defects (1.32 expected) in agriculture and horticulture. Overall, the distribution of risk ratios in the 60 occupations examined was not significantly heterogeneous. Analysis of chemical exposure profiles for each occupational group showed no evidence of any increased risk, perhaps due to lack of sensitivity and discrimination in this method of exposure estimation. In 152 pregnancies of doctors and nurses who had administered antineoplastic drugs in the first month eight defects, miscellaneous in type, were observed compared with 4.05 expected (p = 0.05). Special study of musculoskeletal defects and work demands showed some evidence of an association with a long working week (greater than or equal to 46 hours) but no other ergonomic factor. With these few exceptions the survey failed to identify appreciable risk of congenital defect related to occupation.

Anesthetics↗

PubMed1988

[A program of research on biocultural dynamics].

"The objective of the research program presented in this note is to analyse the interrelations between biological and social factors in the process of demographic renewal. Population registers of various communities, among them those of Saint-Barthelemy (French Antilles) and Ile-aux-Coudres (Quebec), are used. The genealogies which were obtained from these registers contribute to the study of genetical epidemiology. The research program also includes the identification of social factors which may have contributed to the biological structure of the communities under study." (SUMMARY IN ENG AND SPA)

Americas↗

PubMed1987

Activities of neuronal and astrocytic marker enzymes in autopsied brain tissue from patients with hepatic encephalopathy.

Activities of the gamma-aminobutyric acid (GABA) and cholinergic nerve-terminal marker enzymes glutamic acid decarboxylase (GAD) and choline acetyltransferase (CAT) as well as the astrocytic enzyme glutamine synthetase (GS) were measured in homogenates of dissected brain tissue obtained at autopsy from nine cirrhotic patients dying in hepatic encephalopathy and an equal number of control subjects matched for age, agonal status, and time interval from death to freezing of autopsied material. GAD activities varied as a function of agonal status in control samples, confirming a previous report, but were unchanged in brain tissue from cirrhotic patients, suggesting no loss of integrity of presynaptic GABA nerve terminals in this disease. On the other hand, GS activities were selectively decreased by 25% (P less than 0.01) in caudate nuclei of cirrhotic patients, reflecting, no doubt, the severe astrocytosis consistently observed in this brain structure. CAT activities, expressed per milligram of protein, were found to be increased by 30% (P less than 0.01) in the prefrontal cortex of cirrhotic patients. Whether such changes result from a relative increase in CAT as a consequence of losses of astrocytic protein or reflect altered cholinergic function in hepatic encephalopathy associated with chronic liver disease awaits further study.

Aged↗

PubMed1987

Amino acid changes in autopsied brain tissue from cirrhotic patients with hepatic encephalopathy.

Brain tissue was obtained at autopsy from nine cirrhotic patients dying in hepatic coma and from an equal number of controls, free from neurological, psychiatric, or hepatic diseases, matched for age and time interval from death to freezing of dissected brain samples. Glutamine, glutamate, aspartate, and gamma-aminobutyric acid (GABA) levels were measured in homogenates of cerebral cortex (prefrontal and frontal), caudate nuclei, hypothalamus, cerebellum (cortex and vermis), and medulla oblongata as their o-phthalaldehyde derivatives by HPLC using fluorescence detection. Glutamine concentrations were found to be elevated two- to fourfold in all brain structures, the largest increases being observed in prefrontal cortex and medulla oblongata. Glutamate levels were selectively decreased in prefrontal cortex (by 20%), caudate nuclei (by 27%), and cerebellar vermis (by 17%) from cirrhotic patients. On the other hand, GABA content of autopsied brain tissue from these patients was found to be within normal limits in all brain structures. It is suggested that such region-selective reductions of glutamate may reflect loss of the amino acid from the releasable (neurotransmitter) pool. These findings may be of significance in the pathogenesis of hepatic encephalopathy resulting from chronic liver disease.

Aged↗

PubMed1987

Chemical exposures at work in early pregnancy and congenital defect: a case-referent study.

Three hundred and one women who in their most recent pregnancy had given birth to an infant with an important congenital defect were individually matched with 301 women whose children were normal. Both cases and referents were drawn from a comprehensive survey of pregnancies in Montreal, 1982-4, and limited to women employed 30 or more hours a week until at least the 13th week of gestation. Occupational exposure to chemicals was investigated and the results classified without knowledge of case-referent status. In matched pair analysis the overall frequency of chemical exposure was higher in cases than referents (63:47), due to excesses in the cardiac and miscellaneous defect groups (ratios of 10:5 and 15:7 respectively). In analyses by nine chemical categories only exposure to aromatic solvents showed a clear excess (18:8; p approximately equal to 0.04), most evident in the urinary tract group (9:0). A comparison of cases and referents exposed to aromatic solvents showed that most of the excess was associated with toluene; the defects were varied but predominantly renal-urinary or gastrointestinal.

Abnormalities, Drug-Induced↗

PubMed1986

Motor, sympathetic and sensory innervation of rat skeletal muscles.

This study reports on the location, number and size of motor, sympathetic and sensory neurons innervating the following muscles of rat: quadriceps femoris (QF), tibialis anterior (TA), extensor digitorum longus (EDL), peroneus longus (PL), gastrocnemius medius (GM) and soleus (SOL). Cells were labelled by application of horseradish peroxidase (HRP) to transected muscle nerves. Counts of neurons were compared with counts of myelinated (MF) and unmyelinated (UMF) fibers in normal, deafferented and chemically sympathectomized nerves. The topographical arrangement of spinal motor nuclei resembled that reported previously in other mammals and birds. Sensory somata were aggregated without precise somatotopic organization, preferentially in one of the lumbar dorsal root ganglia at a segmental level corresponding to that of the motor innervation. Because lumbar sympathetic ganglia were often poorly circumscribed, the segmental position of sympathetic ganglion cells could not be localized with certainty. Sensory and sympathetic somata demonstrated a unimodal size-frequency distribution, while QF, TA and PL motoneurons could be subdivided according to size in alpha and gamma cells. For all muscles except unsuccessfully deafferented QF, counts of motor fibers after deafferentation correlated closely with counts of labelled motoneurons. Similarly, estimates of sympathetic axons, averaging 30,7% of the UMF, in most instances exceeded only marginally the ganglion cell population. In contrast, the number of peripheral afferent fibers outnumbered markedly that of sensory cell bodies, with an average of 2.8 axons per ganglion cell.

Animals↗

PubMed1986

Differences in horseradish peroxidase labeling of sensory, motor and sympathetic neurons following chronic axotomy of the rat sural nerve.

In an attempt to clarify the ultimate fate of permanently axotomized adult primary neurons, horseradish peroxidase (HRP) was used as a cell marker to label the motor, sensory and postganglionic sympathetic neurons of rat sural nerves which had been sectioned at the ankle and prevented from regenerating for periods of up to 80 weeks. Axotomy did not affect sympathetic neurons, but resulted 4 weeks later in a sudden reduction in the number of labeled sensory and motor cells which persisted to the end of the study. The missing neuronal population amounted to 44.4% and 45.9% respectively of the normal sensory and motor contingent and included most of the large afferent and efferent neurons. However, examination of sural nerves at the thigh, 30 mm proximal to the neuroma, revealed marked axonal atrophy but no change in the number of myelinated and unmyelinated fibers up to 52 weeks after axotomy. Such prolonged survival of the peripheral processes is indirect evidence that axotomized neurons can endure long-term detachment from their end organs and suggests that the lack of HRP labeling in certain sensory and motor neurons does not imply their degeneration, but expresses one of many retrograde dysfunctions triggered by axotomy.

Animals↗

PubMed1986

Carbonic anhydrase activity in the normal and injured peripheral nervous system of the rat.

The carbonic anhydrase reactivity of primary neurons and axons of the L4 and L5 lumbar levels was studied in rats before and after various surgical procedures including transection of the spinal cord, removal of dorsal root ganglia, and transection of ventral or dorsal roots or spinal nerves. In normal animals, carbonic anhydrase reactivity was confined to large and medium size neurons of the dorsal root ganglia, and was also present in a sizeable percentage of cells scattered throughout the thoracolumbar sympathetic chain and in the celiac ganglion. At root level, enzymatic staining could be detected in 48.7% of the dorsal root myelinated axons of most sizes, whereas in ventral roots, it was restricted to small myelinated axons, in a proportion much higher at the L4 than in the L5 level. Spinal motoneurons remained unlabeled, despite procedures aimed at increasing the somal concentration of carbonic anhydrase, such as ventral root ligation and blocking of the fast or slow axoplasmic transport using colchicine or iminodiproprionitrile. However, it is likely that reactive ventral root axons originate from neurons situated segmentally in the spinal cord, and do not constitute aberrant sensory fibers, as carbonic anhydrase activity remained unchanged in the L4 and L5 ventral roots after removal of the corresponding spinal ganglia, whereas it disappeared after damage to the spinal cord at the lumbar level, or at a site distal to a ventral root section. Enzymatic staining of neurons of the dorsal root ganglia was not modified by a dorsal rhizotomy, but showed a marked decrease after transection of the spinal nerve.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1984

Biochemical properties and kinetic parameters of monoamine oxydase in human seminal plasma.

The present study demonstrates that monoamine oxydase (MAO) is present in the human seminal plasma and that its activity was higher in infertile than in fertile men. The Km and Vmax of the enzyme were, respectively, 3.0 X 10(-3) M and 625 eta mol of deaminated 5-HT mg of prot-1 min-1. The enzyme was activated by pyridoxal-5' phosphate but inhibited by usual MAO inhibitors such as pargyline-HCl, iproniazid-PO4 and clorgyline. These findings suggest a relationship between the synthesis and degradation of biogenic amines and testicular function.

Enzyme Activation↗

PubMed1978

[Histological and morphometric study of the development of the optic part of the compound eye of the Enallagma boreale Selys (Odonata: Coenagrionidae)].

The morphology of the optical part of the Enallagma boreale Selys compound eye remains unchanged during its post-embryonic development. The cornea, composed of the epi-, exo- and endocorne, is in perfect continuity with the larval cephalic cuticle. Consequently these two structures possess the same three layers and have a similar process formation. But, the measurements from cephalic endocuticle and endocornea of the adult differ significantly from each other. The latter has a lamellar aspect. The nuclei cornea reaches its morphometric characteristics as early as the pre-emergence stage. The nuclei of the two primary pigment cells which have maintained their epidermic nature, are located at each side of the apex of the crystalline cone. The nuclei of the secondary pigment cells are uniformly distributed in the optical and photosensitive parts. The larval and adult crystalline cones differ morphometrically. The larval one is longer and narrower and reaches its adult characteristics just before emergence. Statistical tests do not show any significant difference between the dorsal and the ventral parts of the larval and adult compound eye.

Animals↗

PubMed1975

Effect of intravenous diazepam on renal function.

The effect of intravenous diazepam on glomerular filtration rate (inulin clearance) and effective renal plasma flow (PAH clearance) was investigated in 6 children and 12 anesthetized rabbits. A transient decrease in inulin and PAH clearances was observed in 6 children given 4 mg of diazepam intravenously, without measurable change in blood pressure. A similar renal effect was observed in anesthetized rabbits, together with a transient drop in systemic arterial pressure. Continuous infusion of diazepam (5 mg/kg/hr) did not affect renal function in rabbits. We suggest that this effect of diazepam should be borne in mind when the drug is administered to patients undergoing renal clearance studies or to patients with preexistent renal insufficiency.

Aminohippuric Acids↗