Showing papers by "Laval University published in 1981"

Immunoreactive substance P and serotonin present in the same dense-core vesicles

Abstract: It is well known that several endocrine cell types, particularly those found in the gastrointestinal tract, contain not only peptidic hormones but also a biogenic amine1,2. Furthermore, it has recently been reported that a neuropeptide, substance P, and a classical neurotransmitter, serotonin, have been found in the same neurones in the central nervous system3,4. However, these light microscopy studies were unable to elucidate the sites of storage of the two substances. Moreover, there is no information about the organelles involved in the storage of neuropeptides and biogenic amines which coexist in the same neurones, although it is well established that neuropeptides are mostly found in dense-core vesicles of terminals5–7. To confirm these previous results and to identify the storage organelles, we localized substance P and serotonin on consecutive ultrathin sections by immuno-electron microscopy. As we report here, we found that, in both raphe nuclei and dorsal horn of the spinal cord, no more than 20% of serotonin-containing nerve terminals were also positive for substance P. In these terminals, both substances were found in the same large dense-core vesicles (60–90 nm diameter). These results strongly suggest that, in appropriate conditions, the two substances are released simultaneously.

Old and new finite elements for incompressible flows

Abstract: SUMMARY This paper presents some seemingly new elements for the computation of two and three-dimensional incompressible flow. We want to obtain elements satisfying the BabGska-Brezzi condition for mixed methods and thus introducing no spurious pressure modes (cf. Sani et al.'). In order to present clearly the advantages and disadvantages of our new elements we compare them on a qualitative basis with more standard ones. Of particular importance for incompressible flow is the size and shape of vortices that can be produced by the elements. We shall try to describe this as precisely as possible. The conclusion is that the elements introduced here should be quite competitive on a costiprecision scale.

Association of oral Bacteroides with gingivitis and adult periodontitis.

Abstract: The microbial flora of healthy gingival crevices and of periodontal pockets was studied to determine if a relation exists between the presence of Bacteroides asaccharolyticus and/or saccharolytic subspecies of B. melaninogenicus and the severity of the disease. Seventy-eight samples were collected with sterile absorbent points from 40 individuals. The samples were immediately placed in reduced transport fluid. After dispersal by sonic treatment, the samples were put into an anaerobic chamber, serially diluted and plated on modified MM10 medium. After incubation, plates were examined and major bacterial types were counted. Black-pigmented colonies were selected for further characterization. Samples from patients with severe inflammation (gingival index, GI = 3) showed a greater proportion of Gram-negative anaerobic rods and 31.8 % of these organisms were identified as B. asaccharolyticus. This organism was absent in healthy sulci. It was recovered from mildly inflamed sites (GI = 1 or 2) but less often than B. melaninogenicus ss intermedius. B. melaninogenicus ss melaninogenicus was found only occasionally and in low numbers.

Human papillomavirus infection of the cervix: the atypical condyloma.

Abstract: We report on 162 cases of human papillomavirus (HPV) infection of the cervix seen in a two-year period in which the cell sample showed such marked atypia that errors of interpretation could easily have been made. These atypical condylomata are difficult to diagnose cytologically as well as histologically because they mimic dysplasia or carcinoma in situ and, on smears, even invasive squamous carcinoma. HPV particles associated with fibrillar material were found within nuclei of these lesions; their nature was further proved by the immunoperoxidase test. This new form of HPV infection of the cervix showed a 9.1% rate of progression to more advanced cervical lesions. The cytologic finding of atypical condylomata is an indication for colposcopy, confirmative biopsy and appropriate treatment.

Intracortical arborizations and receptive fields of identified ventrobasal thalamocortical afferents to the primary somatic sensory cortex in the cat.

Abstract: The intracortical arborizations of neurons from the ventroposte- rolateral thalamic nucleus (VPL) in the cat were studied by intraaxonal injections of horseradish peroxidase (HRP) following identification of their receptive fields. In the primary somatic sensory cortex (SI) VPL cells terminated in different cyto- architectonic areas according to their receptive field modality. Fibers excited by deep tissues or joint rotation arborized preferentially in area 3a. Those responding tonically to cutaneous stimuli were located in the anterior part of area 3b; hair- driven cells terminated in area 3b and in the rostra1 pole of area 1. All fibers had a similar laminar distribution within SI. Axons terminated mostly in layers VI, IV, and the lower part of layer 111. None terminated in layers I and 11. Most terminal arbors were oriented along the mediolateral axis of the brain. The main arboriza- tion of a single VPL cell formed a bush of about 500 pm in diameter. Some fibers generated two such bushes with an uninvaded region of about 300 pm between them. It is proposed that this patchy organization underlies in part the columnar organization of area SI. Many VPL cells had secondary projection sites in SI. These were issued from smaller-sized collaterals and were located in a different cyto- architectonic area than that ofthe main terminal plexuses. A significant number of these collaterals projected to area 4. Insufficient filling of the collaterals by HRP prevented a more complete characterization of the secondary arbors. The cortical column is a concept that has proved useful in understanding the cerebral cortex. The existence of columns was first sug- gested by Mountcastle ('57). He showed that cells recorded along a perpendicular tract in the primary somatic sensory (SI) cortex had over- lapping receptive fields and that they all re- sponded to the same modality of stimulation. Later, Hubel and Weisel ('62, '69) demon- strated the existence of orientation and ocular dominance columns in the primary visual area. The radial arrangement of nerve cells in many cortical regions often suggests columnar arrangements. Lorente de NO ('38) pointed out that the cortical unit is a narrow cylinder of cells stretching from layer I1 to layer V1 and having roughly columnar shape. Colonnier ('66) stressed the preferential vertical orienta- tion of axons of many cortical cells and sug- gested that they are for processing inputs into vertical chains of neurons. He also emphasized that if the cortical circuitry has the necessary wiring for supporting the existence of cortical columns "the anatomical columns are not dis- tinct separate morphological entities." This implicitly suggested that the territorial limits of the functional columns were determined by the connectivity of thalamocortical afferents and by the tangential spread of inhibition within the cortex. In the primary visual area, ocular dominance columns have their morpho- logical basis in the alternating patches of ter- minal ramifications of geniculocortical afferents (Huber and Weisel, '69; Ferster and LeVay, '78; Gilbert and Weisel '79). More re- cently, the patchy nature of the cortical projec- tion from the ventroposterolateral (VPL) nu- cleus of the thalamus has also been demon- strated by autoradiography (Friedman and Jones, '80). Since the topographic charac- teristics of cortical columns appear to be deter- mined by thalamocortical input, we injected single VPL afferents below SI after identifica- tion of their receptive fields. The aim of this

From Gaussian beam to complex-source-point spherical wave

Abstract: It is shown that the paraxial Gaussian beam becomes the complex-source-point spherical wave when all-order corrections are made according to the method of Lax, Louisell, and McKnight. Apparent contradictions between previously published first-order corrections are also discussed.

Characteristics of the α-Adrenergic Stimulation of Adrenocorticotropin Secretion in Rat Anterior Pituitary Cells

Abstract: Specificity of the a-adrenergic control of ACTH secretion was studied in rat anterior pituitary cells in primary culture. The α-adrenergic specificity of ACTH secretion is demonstrated by the following order of potency of catecholaminergic agents: epinephrine (20 nM) > norepinephrine (30 nM) » isoproterenol = doparnine (10μM). While epinephrine and norepinephrine lead to a 7- to 10-fold stimulation of ACTH secretion, clonidine and phenylephrine act as partial agonists and cause a 3- to 4-fold increase of ACTH release. Paraaminoclonidine and methoxamine have no significant effect up to 10 μM. α-Adrenergic antagonists inhibit epinephrine-induced ACTH release in the following order of potency: prazosin > WB-4101 » yohimbine, with Ka values of 0.06, 0.4, and 70 nM, respectively, thus indicating that the α-adrenergic receptor controlling ACTH secretion is of the α1 type. Dihydroergocornine and dihydroergocryptine, two ergot derivatives, show a-adrenergic antagonistic activity at low Kd values of 0.8 and 1.5 nM...

The monoamine-containing neurons in avian brain: I. A study of the brain stem of the chicken (Gallus domesticus) by means of fluorescence and acetylcholinesterase histochemistry.

Abstract: The distribution of monoamine (MA)-containing nerve cell bodies in the brain stem of the chicken (Gallus domesticus) was studied by means of paraformaldehyde and glyoxylic acid fluorescent histochemical methods. The MA neurons were further characterized morphologically and histochemically in material prepared for the demonstration of acetylcholinesterase (AChE). In the rostral midbrain of the chicken, two large collections of catecholamine (CA)-containing cells are found: one located in the ventromedial and the other in the dorsolateral (pedunculopontine nucleus) portions of the tegmentum. On the basis of their topographic location, CA content, and fiber connections, these ventromedial and dorsolateral cell groups can be tentatively associated with the CA-containing neuronal populations of the mammalian ventral tegmental area and pars compacta of the substantia nigra, respectively. In the caudal midbrain of the chicken, numerous CA-containing cells are intermingled with serotonin (5HT)-containing perikarya beneath as well as within the decussation of the superior cerebellar peduncles. At isthmus levels, abundant, closely-packed CA-containing cells are encountered along the lateral border of the central gray. These neurons, which display a very high AChE activity, appear to be equivalent to those of the mammalian locus coeruleus. A multitude of medium-sized 5HT-containing neuronal somata occurs within the raphe region of the isthmus. Some of these somata closely surround the medial longitudinal fasciculus. This 5HT-containing cell group also massively invades the lateral tegmentum, where it becomes closely intermingled with the CA-containing neurons of the locus coeruleus and subcoeruleus. All of these 5 HT-containing neurons display a moderate to high AChE activity. In the medulla the number of MA-containing neurons is much smaller than in the upper brain stem. Nevertheless, 5HT-containing cells are present within the raphe region, particularly in the upper two-thirds of the medulla, and CA-containing perikarya can be found along the lateral border of the medulla and within the confines of the nucleus solitarius. The findings of the present study reveal that the MA-containing neuronal systems in the avian brain stem are organized according to a pattern that is much more complex than the one disclosed in reptiles or in other nonmammalian vertebrates. This complexity arises in large part from the fact that the 5HT-containing systems undergo a prominent lateralization in birds, which leads to a close intermingling of 5HT-containing and CA-containing neuronal elements at various levels of the neuraxis.

Modification of calmodulin function by enzymatic carboxyl methylation

Abstract: Calmodulin is a ubiquitous calcium-binding protein that regulates a variety of enzymes such as adenylate cyclase, cyclic nucleotide phosphodiesterase, ATPase and protein kinase (for review see ref. 1). So far, no enzymatic modification of calmodulin has been shown to affect its function. Another ubiquitous protein, the enzyme protein-carboxyl methylase (PCM), modifies proteins post-translationally by methylating their free carboxyl groups and thus neutralizing negative charges2–6. This enzyme is one of three elements of the protein-carboxyl methylation system; the two others are the substrates, the methyl acceptor proteins (MAP) and the demethylating enzyme, protein methylesterase (PME)7. We report here that calmodulin is an exceptionally good substrate for PCM and that the enzymatic post-translational methylation of calmodulin inhibits its stimulatory effect on cyclic nucleotide phosphodiesterase. Furthermore, we present evidence that carboxyl methylation of calmodulin occurs in intact cells.

Studies on the sparing effect of exercise on insulin requirements in human subjects

Abstract: The reduced insulin response of trained subjects in the presence of normal glucose tolerance has been confirmed. It was also found that this beneficial effect of exercise is greatly reduced if trained subjects are inactive for 3 days while eating ad libidum. During that period excessive food intake (3291 cal/day) was noted. However, when the subjects were on a restricted diet (2076 cal/day) the reduced insulin response to a glucose load was retained. The ratio of food intake with regard to caloric utilization is possibly the important modulator of the action of exercise on insulin requirements. The effect of exercise on insulin secretion was also found to be acquired rapidly since it was observed 18 hr after 1 hr of physical activity at 70% of V02 max in non-trained subjects. For all these studies a correlation (p less than 0.01) was found between the secretion of insulin in response to glucose challenge and both basal plasma glucose and insulin.

Stromal myofibroblasts in primary invasive and metastatic carcinomas. A combined immunological, light and electron microscopic study.

Abstract: A series of 23 primary invasive and 7 metastatic carcinomas was examined by light microscopy (LM), transmission electron microscopy (TEM) and immunofluorescence (IF), the latter employing an anti-actin antibody. The results were correlated with macroscopic features such as retraction and consistency. Stromal cells rich in actin, readily identified by IF in firm and retracted carcinomas, were rare or absent in neoplasms lacking these features. TEM established the myofibroblastic nature of these stromal cells. Alternate sections (LM, IF) of each neoplasm demonstrated that myofibroblasts were more numerous in “young” mesenchymal stroma than in densely sclerotic areas. The connective tissue adjacent to intraductal mammary carcinoma lacked myofibroblasts, suggesting that epithelial stromal invasion is required to evoke a myofibroblastic stromal response. Myofibroblasts which possess synthetic (type III collagen) and contractile properties may well contribute to the firm consistency and retraction which characterize many carcinomas. The induction of myofibroblasts might represent an important host stromal response directed toward containment of invasive and/or metastatic carcinoma. This response may be especially important in neoplasms with weak antigenicity and/or slow doubling times.

On the signal-to-noise ratio and short-term stability of passive rubidium frequency standards

Abstract: Results are presented on theoretical calculations of the signal-to-noise ratio and of the short-term stability realizable in passive rubidium frequency standards. Measurements made on systems using either the separate hyperfine filter or the integrated hyperfine filter approach are reported. It is concluded that shot noise produced by the lamp at the photodetector is responsible for the observed white frequency noise spectrum limiting the stability in the short-term region.

Confirmation of the papillomavirus etiology of condylomatous cervix lesions by the peroxidase-antiperoxidase technique.

Abstract: The peroxidase-antiperoxidase technique with the use of paraffin sections of 67 cervical biopsy specimens and an antiserum cross-reactive with all papillomaviruses provided immunologic confirmation for the observation that papillomavirus infection of the cervix is not uncommon and that it most often presents as a flat, colposcopically unremarkable lesion. Papillomavirus antigen was detected in 21 or 35 condylomata of the cervix. Antigen-positive nuclei were found in the upper layers of the epithelium. Electron-microscopic examination of five reprocessed antigen-positive sections revealed, in each instance, papillomavirus particles in the nuclei of the most superficial layers of the condylomatous epithelium. The viral antigen was not detected in dysplasia, carcinoma in situ, or invasive carcinoma.

Androgens decrease lhrh binding sites in rat anterior pituitary cells in culture

Abstract: [125]-[D-Ser(TBU)6]LHRH-EA binds to a single class of high affinity sites in rat anterior pituitary cells in culture at an apparent dissociation constant of 0.25 nM at 0–4C. The order of potency of a representative group of LHRH agonists and antagonists to displace the labeled ligand is similar to their LH-releasing activity. Treatment of pituitary cells for 48 h with 100 nM 5α-dihydrotestosterone leads to a 40% decrease of the number of LHRH receptors with no change of binding affinity. This loss of LHRH receptors is accompanied by a similar decrease of the LH responsiveness to LHRH, thus providing the first evidence for a direct effect of sex steroids on pituitary LHRH receptors as a possible mechanism of feedback action.

Freedom from ototoxicity in aminoglycoside treated neonates: a mistaken notion.

Abstract: Pediatricians commonly consider aminoglycoside antibiotics to be less ototoxic in neonates than in adults. This concept is based on the results of pure tone audiometry performed in children treated with aminoglycosides during the neonatal period. However, conflicting results were obtained when using brain stem response audiometry (BSRA) in a group of 26 aminoglycoside treated neonates and a control group of 20 treated neonates during their stays in intensive care units (mean gestational age: 34.6 weeks). Latencies of wave V significantly differed between the two groups indicating hearing alterations in the treated group. A statistical correlation was demonstrated between initial and final values of wave V and the total doses of antibiotic administered per kilogram of body weight (p < 0.01). Most neonates were premature with an immature hearing apparatus. To demonstrate the effect of aminoglycosides on the developing organ of Corti, neonate kittens were chosen as animal models — the onset of hearing occurs 10 days after birth. BSRA was performed every 3 days from birth for 20 days and thereafter every 6 days for the following 30 days. Five kittens treated with a low dose of gentamicin for 20 days were compared with a control group of 5 untreated kittens from the same litters and a group of S adult cats receiving the same antibiotic therapy. On the 50th day, all animals were sacrificed and their cochleas were prepared for electron microscopic evaluation. No ultrastructural modifications or BSRA alterations were noted in the adult group. The untreated kittens exhibited a normal pattern of BSRA maturation and their organs of Corti appeared normal. On the contrary, evidence of abnormal hearing maturation and of anatomical damage in the outer hair cells of the first coil of the cochlea was found in the treated kittens. Laboratory findings corroborate our clinical findings that aminoglycoside antibiotics are more ototoxic in neonates than in adult cats.

Cellular regulatory role of leukotriene B4: Its effects on cation homeostasis in rabbit neutrophils

Abstract: We have found that exogenous leukotriene B4 modifies calcium homeostasis in rabbit neutrophils in a manner essentially analogous to that of the chemotactic peptide f-Met-Leu-Phe. Leukotriene B4 causes a rapid and dose-dependent increase in membrane permeability to calcium and a release of calcium from previously unexchangeable intracellular pool(s). The net result of these changes is to transiently elevate the intracellular level of exchangeable calcium. A stereoisomer of leukotriene B4 with greatly reduced secretory activity toward neutrophils (5S, 12S-di HETE) is essentially without effect on the rate of 45Ca uptake at concentrations equal to those that produce near maximal enhancement by leukotriene B4. Leukotriene B4, in addition to its effects on calcium metablolism, also increases the rate of 22Na influx into rabbit neutrophils. The relationships between the action of leukotriene B4 on calcium homeostasis and the neutrophil-directed activities of arachidonic acid and its lipoxygenase metabolites are discussed.