PubMed Health⌕ Search

Biomedical subjects

C Dotti

Publications and source records attributed to C Dotti.

At least 37 records · Page 2Linked to original sources
PubMed1989

Cholesterol microlithiasis: bacteriology, gallbladder bile and stone composition.

It is not known whether microcalculi possess structural differences compared with larger stones or whether they represent simply an earlier stage in stone disease. We carried out a controlled study on 10 patients affected by gallbladder cholesterol microlithiasis (CM). In all patients, samples from all parts of the stones were studied by X-ray diffraction and by infrared spectrophotometry. Bile analysis was carried out to determine cholesterol, phospholipid and total bile acid content. The cholesterol saturation indices (C.S.I.) were calculated. In all samples, bacterial bile culture was carried out. The results were compared with those of 10 patients who had undergone cholecystectomy for large cholesterol stones, and for 10 patients who had undergone abdominal surgery but without biliary pathology. Patients in these latter groups were matched with the first according to sex and age. Microcalculi proved to be layered (nucleus and external layer) in only 2 cases and larger stones in 9; cholesterol was seen to be the principal crystalline component in all cases. Traces of bilirubin were found in 7 CM and in the nuclei of 5 larger stones. These results show that the structural composition of microcalculi is similar to that of the nucleus of larger stones. No substantial differences exist, however, between the two groups of patients regarding the other parameters taken into consideration.

Adult↗
PubMed1989

Calcitonin inhibition of growth hormone-releasing hormone-induced GH secretion in normal men.

Calcitonin has been shown to modulate pituitary hormone secretion in a variety of ways. In this study we examined the effects of a salmon calcitonin infusion on GHRH-induced GH secretion in 5 normal men. In addition, in vitro experiments were performed using primary cultures of rat anterior pituitary cells in order to examine whether there is a direct pituitary effect of CT. Infusion of CT significantly blunted the GH response to GHRH in all subjects without affecting basal GH secretion or plasma calcium levels. Infusion of CT was accompanied by significant increases in ACTH, beta-endorphin, cortisol and free fatty acid levels, and by a significant decrease in serum insulin levels. The addition of CT to primary cultures of rat pituitary cells did not alter basal or stimulated secretion of GH or ACTH. These results indicate that: 1) CT blunts the GH response to GHRH; 2) CT infusion results in the stimulation of the hypothalamic-pituitary-adrenal axis, and 3) this effect is probably exerted at the hypothalamic level, since no direct activity of CT was documented in vitro on either GH or ACTH secretion.

Adrenocorticotropic Hormone↗
PubMed1988

Protein synthesis and processing in cytoplasmic microdomains beneath postsynaptic sites on CNS neurons. A mechanism for establishing and maintaining a mosaic postsynaptic receptive surface.

Recent studies have shown that protein synthetic machinery consisting of polyribosomes and associated membranous cisterns is selectively localized beneath synaptic sites on neurons. In the present paper, the role of this machinery in neuronal function will be considered. We will: 1. Summarize the studies that characterize the polyribosomes and define their associations with membranous cisterns. Taken together, these observations suggest the existence of a system for the synthesis and posttranslational processing of proteins at individual synaptic sites; 2. Review the evidence that the protein synthetic machinery is particularly prominent during the initial formation of synaptic contacts (during early development), and during lesion-induced synaptogenesis in mature animals. These observations have led to the hypothesis that the polyribosomes produce proteins that play a role in the formation of the synaptic junction; 3. Review evidence that supports the hypothesis that there is a local synthesis of protein within dendrites, as well as local glycosylation; 4. Describe the evidence suggesting that at least some of the protein constituents of the synaptic junction itself are synthesized locally; and 5. Describe our studies that reveal a mechanism for selective dendritic transport of RNA; this transport mechanism permits the delivery of RNA to postsynaptic sites throughout the dendritic arbor. We will advance the hypothesis that neurons position protein synthetic machinery together with the mRNA's that are appropriate for particular synapses beneath synaptic contact regions. At the synaptic site, this machinery could then direct the synthesis of particular proteins that are critical for synapse formation or maintenance. The positioning of protein synthetic machinery at postsynaptic sites permits a rapid local regulation of the production of key proteins by events at individual synapses.

Animals↗
PubMed1988

Serotonin regulation of aldosterone secretion.

The circulating levels of aldosterone (A), cortisol (F), prolactin, ACTH and potassium and the PRA were studied in 8 (6 males and 2 females) healthy normotensive subjects after 5-hydroxy-tryptophan (5OHT), or pizotifen (Piz) or placebo oral administration. In the same subjects 5OHT was administered twice: after placebo and after dexamethasone pretreatment. The results showed a significant increase of A, ACTH and F after 5OHT plus placebo administration without any change of PRA, potassium or prolactin levels; dexamethasone pretreatment suppressed ACTH and F but was uneffective on the response of A to 5OHT. Only A levels showed a significant decrease after Piz administration, the other studied parameters were unaffected by the blockade of the 5HT2 receptors by Piz. The administration of placebo induced a slight but not significant decrease of the studied parameters. Our results suggest the existence of a physiologic serotonergic control of A secretion, a pituitary factor could be one of the putative links between the central serotonergic activation and the adrenal secretory response.

5-Hydroxytryptophan↗
PubMed1987

Effect of oral administration of melatonin on GH responses to GRF 1-44 in normal subjects.

In order to investigate the role of melatonin on the neuroregulation of GH secretion, eight healthy male volunteers each underwent four separate tests in random order separated by at least 1 week. Following oral administration of melatonin (500 mg at -60 min and at -30 min) plasma GH levels were higher than after placebo at 45 min (mean +/- SEM 2.9 +/- 0.8 vs 0.9 +/- 0.4 ng/ml, P less than 0.01) and 60 min (mean +/- SEM 2.9 +/- 0.4 vs 0.8 +/- 0.1 ng/ml, P less than 0.05). Likewise, after prior administration of melatonin, GH responses to GRF 1-44 (1 micrograms/kg i.v. at 0 min) were greater than placebo plus GRF at 15 min (mean +/- SEM 22.4 +/- 6.1 ng/ml vs 11.3 +/- 2.3 ng/ml, P less than 0.05), 45 min (mean +/- SEM 26.2 +/- 5.3 ng/ml vs 13.3 +/- 2.5 ng/ml, P less than 0.01) and 60 min (mean +/- SEM, 24.7 +/- 7.4 ng/ml vs 11.1 +/- 2.5 ng/ml, P less than 0.05). In contrast we did not observe any effect of either 10(-9)M, 10(-7)M melatonin on in-vitro basal GH release and GH responses to 10(-8)M GRF by rat anterior pituitary cells in monolayer culture. These data suggest that melatonin plays a facilitatory role in the neuroregulation of GH secretion, probably by acting at the hypothalamic level.

Administration, Oral↗
PubMed1987

Cross reactions in radioimmunoassay: a mathematical model for correcting assay results, as exemplified by eliminating the interference of intact thyrotropin in an assay of its beta subunit.

To correct the results of a radioimmunoassay for beta-thyrotropin (TSH) subunit by eliminating the proportion ascribable to intact TSH, we have devised a method that experimentally reproduces the conditions under which the interference develops. Beta-TSH subunit was assayed in several preparations containing known concentrations of both beta-TSH and TSH. The TSH-induced overestimation of beta-TSH was linearly related to the concentration of antigen in the sample. At a constant concentration of TSH, therefore, the following equation is applicable: F = aE + b, where F is the measured (but overestimated) concentration of beta-TSH, E is the actual concentration of beta-TSH, and a and b are the slope and the intercept of the regression line, respectively. a and b, once expressed as a function of TSH, allow the correction of the overestimation. The analysis of the results according to the mass action and conservation laws shows that the antiserum is more avid for the interferent (intact TSH) than for the antigen (beta-TSH).

False Positive Reactions↗
PubMed1986

Kennedy disease in an Italian kindred.

An X-linked adult-onset neurogenic muscular atrophy, chiefly proximal, with late involvement of the distal musculature and medulla oblongata was present in 4 members of a single kindred. Associated in all patients were gynecomastia, impotence and essential tremor. Frederickson type IV hyperlipemia was present in 1 patient. Hormonal stimulation tests in 2 patients elicited a borderline low testicular response in the younger of the 2 and a pathological response in the older patient. On the evidence of these and previously reported cases, Kennedy disease would appear to be characterized by an X-linked proximal neurogenic amyotrophy of adult onset and by a testicular endocrine deficit.

Aged↗
PubMed1985

Immunocytochemical localization of tubulin and the high molecular weight microtubule-associated protein 2 in Purkinje cell dendrites deprived of climbing fibers.

The modifications in the localization of tubulin and the high molecular weight microtubule-associated protein 2 were studied in the cerebellum after partial denervation. Both proteins were localized in 40 micron sections using monoclonal antibodies against beta-tubulin (clones Tu9B and Tu12) or microtubule-associated protein 2 (clones AP9 and AP13), and polyclonal antisera against alpha- and beta-tubulin or microtubule-associated protein 2, visualized with the immunoperoxidase method of Sternberger [Sternberger (1979) Immunocytochemistry; Sternberger and Sternberger (1983) Proc. natn. Acad. Sci. U.S.A. 80 6126-6130] or a biotin-avidin system. The destruction of the inferior olive was performed in adult male rats by electrocoagulation or by intraperitoneal administration of 3-acetylpyridine. One day after chemical destruction of the inferior olive, anti-microtubule-associated protein 2 staining with either of the monoclonal antibodies or with the polyclonal antiserum was almost identical to that observed in the cerebellum of non-denervated animals. Specific staining was intense in the cell somata and dendrites and absent in myelinated tracts and in parallel fibers. However, 3 days after the lesion anti-microtubule-associated protein 2 staining showed a clear decrease, both in the proximal and the distal portions of thick secondary and tertiary dendritic trunks of the Purkinje cell. The intensity of the staining was also considerably reduced in the fine dendritic ramifications. By 8 days post-lesion, microtubule-associated protein 2 immunoreactivity began to increase, but only in the portions of the dendrites deprived of the climbing fibre; on the contrary, low immunoreactivity was found in the fine dendritic ramifications which are contacted by normal parallel fibers; microtubule-associated protein 2 immunoreactivity increased considerably by 11 days post-lesion, giving a pattern quite similar to that of non-denervated Purkinje cells. The alterations in microtubule-associated protein 2 immunoreactivity were also accompanied by a dramatic decrease in the immunostaining for tubulin, beginning on day-3 post-lesion and lasting until day-15 post-lesion. These changes were observed with either the monoclonal antibodies against beta-tubulin or with the polyclonal antiserum against alpha- and beta-tubulin. The changes in both molecules were also observed in animals in which the inferior olive was destroyed by electrocoagulation, ruling out the possibility of a direct action of 3-acetylpyridine on dendritic microtubular proteins.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1984

Beta-adrenergic receptors in the premammillary nucleus mediate the inhibition of LH release evoked by locus ceruleus stimulation.

The neurotransmitter and andrenoceptors involved in the inhibition of luteinizing hormone (LH) release induced by stimulating the locus ceruleus nucleus (LC) have been characterized in ovariectomized, estrogen-primed rats in which the release of LH was triggered by electrical stimulation of the medial preoptic area. Blockade of norepinephrine synthesis by the injection of the dopamine beta-hydroxylase inhibitors, diethyldithiocarbamate or fusaric acid, prevented the inhibition of LH release, whereas blockade of epinephrine synthesis by injecting the phenylethanolamine N-methyltransferase inhibitor, 2,3-dichloro-methylbenzylamine, had no effect. In addition, the inhibition of LH release was prevented by systemic injection of propranolol but not of phenoxybenzamine. This inhibition was also suppressed in rats in which the ventral premammillary (PM) nucleus ipsilateral to the stimulated LC was lesioned, or in animals with a transverse cut placed just in front of the PM. A similar response was seen in rats in which propranolol but not phenoxybenzamine was applied to the PM ipsilateral to the stimulated LC. The present results indicate that norepinephrine, acting through beta-adrenoceptors mediates the transmission of impulses which, originating in the LC, inhibit the release of LH. The LC adrenergic fibers synapse in the PM before the neural information they convey is transfered to the gonadotropin-releasing hormone containing neurons.

Animals↗
PubMed1983

Radioimmunoassayable myoglobinaemia and Duchenne carrier detection.

1 case of Duchenne Muscular Dystrophy (DMD) definite carrier, 3 probable and 17 possible (all analytically positive: "possible +") carriers were classed as Group A, 23 DMD possible carriers (all analytically negative "possible") as Group B and 26 normal subjects as Controls. The three groups were subjected to serum myoglobin (MGB) radioimmunoassay. Since the differences between MGB levels of Group A vs. Controls and Group A vs. Group B were statistically significant, it is suggested that the determination of MGB should be included among the tests for DMD carrier detection.

Adolescent↗
PubMed1979

Simultaneous radioimmunoassay of serum testosterone and 5 alpha-dihydrotestosterone without chromatography.

When characterization of the specificity of an antiserum for radioimmunoassay (RIA) is performed by the conventional method, the conditions under which interference occurs are not respected because of the lack of specific antigen. We have studied the behavior of antisera reproducing the real environment existing in unknown samples, in which antigen, interferent and tracer complete simultaneously. A testosterone (T) antiserum and a 5 alpha-dihydrotestosterone (D) anti serum were characterized by setting up two distinct hapten recovery tests in the presence of both the hapten and the crossreactant added to steroid-free serum in various concentrations in order to reproduce multiple concentration ratios. These samples, together with the standard curves samples (prepared by 'spiking' steroid-free serum with known concentrations of T or D) were extracted and subjected to T-RIA and D-RIA without purification. The results have shown that the interferent-induced incremental ratio is a linear function of the ratio of the levels of cross-reactant and hapten via a proportionality factor inversely correlated to the antiserum specificity. By means of this function, the overestimated T and D levels found in samples after 'extraction only' have been corrected and the resulting values have shown acceptable correlation with the corresponding levels determined after column chromatography.

Cross Reactions↗
PubMed1975

[Radioimmunologic determination of plasmatic triiodothyronine. Verification of operative parameters; 1st clinical results].

The experimental determination of the operative parameters of two radioimmunoassay (RIA) systems for the determination of triiodothyronine (T3) level directly in serum is described. The two systems differ both for the agents blocking the aspecific T3-serum protein bindings (sulphonic acid, 8-aniline, 1-Naphtalene in borate buffer: bor-ANS-RIA and Merthiolate in phosphate buffer: PO4-Merth-RIA) and for the methods adopted for compensating the aspecific serum interferences (T3,4 free serum for bor-ANS-RIA and Human Serum Albumine HSA 8% for PO4-Merth-RIA. The tracers are T3-I125 (spec. act. 500 Ci/g for bor-ANS-RIA and 1000 Ci/g for PO4-Merth-RIA). The antisera have been raised in rabbit (T3-bovine SA conjugate for bor-ANS-RIA and T3-HSA conjugate for PO4-Merth-RIA). The incubation conditions are 2degreesC X 24 h for bor-ANS-RIA and room temp. X 2 h for PO4-Merth-RIA. For both systems, the Bound-Free (B-F) separations are carried out by charcoal-dextrane adsorption, 4 mg/tube, 10 min contact. Indicatively, the lowest detection limits of the two systems are about 8 pg T3 for ANS and about 6 pg T3 for Merth. Evidence of parallelism and even superimposition is provided for both assays between the dose-response curve and the serum dilution curve. The calibration curves of the employed antisera are reported (final titres: 1/1000 for ANS and 1/2500 for Merth). 4 different incubation conditions for ANS and 2 for Merth are described and the reasons of choice of the mentioned conditions statistically elucidated. Acceptable statistical comparison between "sample-blank" and the "blank" of the diluents of the employed standard preparations are presented and discussed. F-countings vs. B-countings functions are reported (regression line -- equations: F = 0.93 B + 0.07, n = 15, r = 0.993 for ANS and F = 0.95 B -- 0.02, n = 14, r = 0.992 for Merth) demonstrating the possibility of alternative countings. The recovery regression lines (found f vs. expected e) have equations: f = 1.01 e + 0.08, n = 10, r = 0.999 for ANS and f = 1.08 e -- 1.64, n = 9, r = 0.995 for Merth, implying a practically quantitative recovery in both cases. Thyroxine (T4) cross reaction study has been undertaken under a quite new optics re-calculating the regression lines -- equations of the T3 recovery in the presence of added T4; in that case, the following equations are valid: f = 1.05 e + 0,13, n = 10, r = 0.992 for ANS and f = 1.07 e + 2.26, n = 18, r = 0,985 for Merth. Reducing the maximum added T4 to 1 ng/tube, the cross reaction can be considered as negligible. T3 levels for normal subjects are finally reported: 1.50 +/- 0.80, n= 37 for ANS and 1.40 +/- 0.68, n = 40 for Merth (ng T3/ml, means +/- 2SD).

Antibody Formation↗