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Biomedical subjects

C J Perec

Publications and source records attributed to C J Perec.

At least 37 records · Page 2Linked to original sources
PubMed1983

Effects of an experimental diet on parotid saliva and dental plaque pH in institutionalized children.

Sixty-six children aged 6-12, permanent residents of a children's home, were placed on a diet during a 45-day experimental period to measure salivary flow-rate, pH of saliva and dental plaque, total concentrations of salivary proteins, inorganic phosphate, bicarbonate, calcium and amylase. The total caloric content, as well as the proportional nutrient and calorie distribution of the foods, were determined and compared with those of the previous habitual diet. After the experimental period, stimulated parotid salivary flow, increased by 40 per cent over the pre-experimental values. Total proteins of saliva and pH of both saliva and dental plaque increased significantly, whereas inorganic phosphate concentration decreased. Concentrations of bicarbonate, calcium and amylase did not differ from those found pre-experimentally. The findings appear to derive from lesser retention and increased hardness of the foods in the experimental diet.

Child↗
PubMed1982

Degeneration activity of the pineal gland after sympathetic denervation.

After removal of the superior cervical ganglia the pineal gland of the rat showed a period of transient increase in activity of serotonin-N-acetyltransferase. This degeneration activity was preceded by a decline of the levels of endogenous noradrenaline and an impairment of the 3H-metaraminol uptake. Twenty-seven hours after sympathetic denervation the levels of the endogenous neurotransmitter were almost completely depleted, while either 24 h or 21 days after denervation total uptake of the tritiated amine decreased to only about 50% of the control values. Previous chronic sympathetic decentralization elicited in the pineal gland post-junctional supersensitivity, as judged by the enhanced degeneration activity observed in decentralized glands after sympathetic denervation. The present findings confirm that, in endocrine glands and similarly to other autonomically innervated organs, acute denervation induces degeneration activity.

Animals↗
PubMed1982

Electron microscopic evidence that bretylium and pargyline delay adrenergic nerve degeneration after sympathectomy of the pineal gland.

Seventeen and twenty four hours after sympathetic denervation, noradrenaline stores of the rat pineal gland were depleted to 50% and 10% of controls, respectively. Electron microscopic studies showed the coexistence of normal and altered nerve endings 17 h after denervation, while 24 h after denervation, only degenerated nerve terminals were observed. Treatment with pargyline (512 mumoles/kg) or bretylium (24 mumoles/kg) significantly delayed the loss of noradrenaline from denervated glands. In pargyline treated rats, 17 h after denervation, noradrenaline stores were 90% of control glands. After bretylium, values obtained 24 h after denervation, declined to 36% of innervated glands. Persistence of neurotransmitter coincided with the presence of normal nerve endings as observed electron microscopically. It is concluded that both, pargyline and bretylium, prolonged the survival of nerve endings severed from the cell body.

Adrenergic Fibers↗
PubMed1982

Delay by drugs of adrenergic nerve degeneration after proximal or distal sympathectomy of the submaxillary gland.

1. Degeneration of nerve terminals of the submaxillary gland of the rat proceeds at a faster rate after crushing adrenergic nerves close to the gland than after ganglionectomy. 2. Bretylium, pargyline, nialamide and clorgyline delayed degeneration to the same extent after either type of denervation. 3. Chlorpromazine and pentobarbitone also delayed adrenergic degeneration, effect related to the hypothermia induced by these drugs. 4. Colchicine applied on the nerve trunk innervating the right gland delayed not only degeneration of the ipsilateral nerve terminals but the contralateral gland as well. 5. From the data obtained it seems probable that the drugs tested delay adrenergic nerve degeneration at the levels of nerve terminals. This effect is not related to lysosomal stabilization.

Acid Phosphatase↗
PubMed1981

[Trophic and functional changes of the pancreas induced by chronic truncal vagotomy].

The effects of chronic truncal vagotomy on the pancreatic gland was studied in male adult Wistar rats. Two to three months after parasympathetic decentralization, the gland weight was found to be significantly increased by nearly 100%. This trophic effect is mainly due to the proliferation of young acinar cells. Concomitantly, there is a decrease of the ductular mass and of the Langerhans islets. Choline acetylase activity was decreased by about 35% to 40% in the vagotomized pancreas. Further, enzyme concentration was found to be greater in the head than in the body and tail of the gland, thus suggesting a higher nerve density of vagal cholinergic fibers in the former than in the latter. Basal pancreatic secretion of the decentralized gland showed a significant increase in the flow rate with no significant changes in both bicarbonate concentration and output. Protein concentration was significantly reduced at 60 minutes; protein output remained unchanged. The most remarkable finding was the fall in both lipase concentration and output (60-70%) when compared with control values. These findings may be related to clinical manifestations after long-term vagotomy.

Animals↗
PubMed1980

Delay by bretylium of adrenergic nerve degeneration after sympathectomy of the submaxillary gland.

Administration of 24 mumol/kg of bretylium 10 h after ganglionectomy delayed the loss of endogenous norepinephrine and the impairment of neuronal uptake of 3H-metaraminol (3H-MA) that follow sympathetic denervation. This delay was evident 16 and 20 h after denervation. Twenty four h after ganglionectomy, when NE stores and uptake of 3H-MA were reduced to their lowest values in untreated rats, in bretylium-treated ones these values were approximately 40% of those in normal glands. The onset of degeneration secretion in treated rats was delayed by about 9 h. The development of prejunctional supersensitivity was also delayed. The subcellular distribution of NE in normal and 16 h denervated glands showed that denervation reduced the neurotransmitter to the same extent in the 3 fractions: coarse, supernatant and microsomal. Treatment with bretylium and pargyline prevented the loss of NE from the microsomal fraction. Previous administration of pargyline antagonized the protection of 3H-MA uptake seen in 28 h denervated rats treated with bretylium. However, this drug combination induced a greater retention of endogenous NE 24 h after denervation. Bretylium inhibited intraneuronal MAO by 40%. It is concluded that bretylium treatment can delay the degeneration of adrenergic nerve terminals separated from the cell bodies by a pharmacological effect probably not related to MAO inhibition or to its neurone blocking action.

Animals↗
PubMed1980

Effect of chronic alcohol feeding on adrenergic and cholinergic neurotransmission mechanism.

Experimental data is presented indicating that chronic alcohol consumption in rats has a direct CNS effect resulting in increased activity of the autonomic nervous outflow. Changes in neurohormonal transmitters have been demonstrated in four organs: salivary glands, spleen, adrenals and heart. These changes may account for the alterations in end organ sensitivity and secretory patterns which occur in alcoholic animals and man. They may, moreover, represent an initial pathogenetic mechanism whereby alcohol induces its various clinical syndromes.

Acetylcholinesterase↗
PubMed1979

Effects of sympathectomy on the in vivo alpha and beta-responses of the parotid gland.

Salivary secretion in response to noradrenaline and isoprenaline was measured in innervated and chronically sympathectomized parotid glands of the rat. In innervated glands, the responses to isoprenaline lasted longer than those to noradrenaline. Chronic sympathetic denervation enhanced the responses to both noradrenaline and isoprenaline. The magnitude of the supersensitivity to isoprenaline was related to the dose and the time at which the responses were analyzed. Supersensitivity was greater for the initial than for the total secretion elicited by isoprenaline. Propranolol (1 mg/kg) and phentolamine (5 mg/kg) were used in order to determine the relative participation of alpha and beta-adrenoceptors in the enhanced responses to isoprenaline. The results suggest that postjunctional supersensitivity for the secretory responses of this organ to isoprenaline is mainly mediated through beta-adrenoceptors of the secretory cells and alpha-adrenoceptors of the myoepithelial cells.

Animals↗
PubMed1979

Effects of sympathectomy on the in vitro alpha and beta-responses of the parotid gland.

Amylase and K+ resease were measured in slices obtained from innervated and sympathetically denervated rat parotid glands. Amylase release induced by noradrenaline was found to be increased after chronic denervation. The postjunctional component of supersensitivity to noradrenaline was evidenced by an increase in the maximal response to this agonist. The maximal response of denervated glands was blocked by propranolol 10(-5) M. On the other hand, chronic denervation did not modify the alpha-adrenoceptor-mediated response, K+ release, either in the presence or in the absence of ouabain. It is concluded that, after sympathetic denervation, postjunctional supersensitivity develops for the beta-adrenoceptor-mediated but not for the alpha-adrenoceptors-mediated effects of noradrenaline.

Amylases↗
PubMed1978

Acetylcholine-like activity in the fruit of the black nightshade (Solanaceae).

The presence of acetylcholine in aqueous extracts of the fruit of Solanum nigrum Linn. (black nightshade) has been established based upon the following pharmacological tests: a) isotonic contraction of the isolated toad rectus abdominis; b) negative chronotropic and inotropic action on the isolated toad heart; c) isotonic contraction of the isolated guinea pig's ileum; d) isotonic contraction of the rat's isolated jejunum; 3) decrease on the cat's arterial blood pressure; f) secretory effects on the rat's submaxillary gland. These actions were selectively blocked by curate or atropine and disappeared after incubation of the extract at 37 C with plasma. Further evidence showing that the fruit of the black nightshade contains acetylcholine was obtained by chromatographic separation of the aqueous extract. The average content of acetylcholine was found to be 250 micrograms/g of fruit.

Acetylcholine↗
PubMed1977

Secretory effects of 6-hydroxydopamine in normal and denervated submaxillary glands of the rat.

Injection of 6-hydroxydopamine (6-OH-DA) elicited a marked and sustained secretory response of control and surgically sympathectomized submaxillary glands of rats. These responses were diminished by previous treatment with reserpine 0.1 mg/kg 48 and 24 h before the experiment and almost abolished by 5 mg/kg reserpine 6 h before the administration of 6-OH-DA. The responses to 6-OH-DA were potentiated in control glands by previous preganglionic denervation of either the parasympathetic or sympathetic nerves of the gland. Development of postjunctional supersensitivity in denervated glands also increased the responses to 6-OH-DA, while atropine had a feeble blocking action. For all these responses, the adrenal catecholamines played no role. After two consecutive doses of 6-OH-DA a third dose of the drug still elicited a secretory response that was 50% of that of the first dose. It is concluded that for the responses to 6-OH-DA the leakage of noradrenaline from the degenerating adrengic nerve endings of the submaxillary gland plays a partial role. Noradrenaline released by the drug from other tissues and reaching the gland via the circulation also contributes to the responses observed. A muscarinic component may also participate in the secretory effects of 6-OH-DA.

Adrenal Medulla↗
PubMed1975

Effects of 6-hydroxydopamine Treatment at birth on the submaxillary gland of the rat.

Six and 18 months after neonatal administration of 6-hydroxy-dopamine or surgical sympathetic denervation the submaxillary gland of the rat showed a marked depletion of noradrenaline stores. Six months afer removal of the superior cervical ganglion the gland's endogenous noradrenaline was lowered to 0.032 +/- 0.004 mug/g while after neonatal 6-hydroxydopamine the values were 0.228 +/- 0.023 mug/g (controls 2.145 +/- 0.382 mug/g). Eighteen months after either type of sympathetic denervation the neurotransmitter was still depleted. In rats treated with 6-hydroxydopamine the sailagogue effect of injected noradrenaline was potentiated 2.7-fold while the potentiation of the effect of noradrenaline was 3.6 times after surgical denervation. The magnitude of the supersensitivity developed to isoprenaline did not differ between both types of denervation. No supersensitivity to the cholinomimetic agent, methacholine, was observed. Cocaine administration or removal of the superior cervical ganglion slightly increased the supersensivity to noradrenaline in rats treated with 6-hydroxydopamine. Eighteen months after surgical or chemical denervation, the activity of choline-acetyl-transferase in the submaxillary gland was increased by about 50%. Of the respiratory enzymes studied, sussinic dehydrogenase, fumarase and cytochrome oxidase, the activity of only the latter was markedly reduced by a chronic sympathetic denervation. From the results obtained it is concluded that neonatal treatment with 6-hydroxy-dopamine causes a permanent and almost complete sympathectomy of the submaxillary gland of the rat.

Aging↗
PubMed1974

Functional studies of the parotid and pancreas glands in amyotrophic lateral sclerosis.

Functional studies of the pancreas and parotid glands are reported in 17 patients with amyotrophic lateral sclerosis (ALS). The exocrine function of the pancreas was studied by measuring amylase concentration after stimulation with the endogenous secretin-pancreozymine test (ESP). Under these conditions, the pancreatic amylase concentration in ALS patients was found to be markedly decreased by about 45% when compared with those of healthy control subjects. Different conclusions in the literature about a possible impairment of the exocrine pancreas in ALS patients induced us to study the function of the parotid gland, which has close structural, functional, and physiopathological relationship with the pancreas. Flow rate and bicarbonate concentration of parotid saliva were measured after indirect stimulation (intraoral citric acid) and direct stimulation (pilocarpine). After indirect stimulation, both parotid flow rate and bicarbonate concentration from ALS patients were found to be decreased by about 66% and 70% respectively, when compared with controls. On the other hand, direct stimulation with pilocarpine in ALS patients elicited normal responses in both flow rate and bicarbonate concentration of saliva. It is concluded that the pancreatic and parotid deficiencies observed in ALS patients do not indicate primary disease of these exocrine glands. This interpretation is further emphasized by the results obtained by a sweat test, plasma osmolarity, and sialographic studies. The possibility that the gland impairments observed might be due to modifications of the neuroendocrine mechanisms regulating their secretory activity is suggested.

Adult↗