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Biomedical subjects

A Conti

Publications and source records attributed to A Conti.

At least 73 records · Page 4Linked to original sources
PubMed1987

Dihydroergocriptine in management of microprolactinomas.

The effects of dihydroergocriptine (DHECP), a dihydrogenated ergot alkaloid with dopaminergic agonistic and alpha-adrenergic antagonistic properties, were studied in 22 women with PRL-secreting microprolactinomas and compared with those recorded in 36 previously studied patients treated with bromocriptine (BRC). After acute administration of 5 mg DHECP, orally, serum PRL decreased by 61 +/- 18% (+/- SD); only 1 patient was unresponsive. The nadir was reached at 300 min. Long term treatment with increasing DHECP doses caused a progressive PRL fall from 125 +/- 142 (+/- SD) to 81 +/- 159 micrograms/L after 1 week of a 3 mg twice daily regimen, to 64 +/- 88 micrograms/L after 1 week of 5 mg twice daily, 46 +/- 57 micrograms/L after 1 week of 10 mg twice daily, and 28 +/- 34 to 33 +/- 45 micrograms/L throughout 9 months of treatment with 10 mg DHECP 3 times daily. Seventy-seven percent of patients had normal serum PRL levels during chronic treatment. All women, including those with supranormal serum PRL levels, resumed regular menses, and 16 had ovulatory cycles; 1 woman became pregnant. Galactorrhea disappeared in all. During treatment the PRL response to TRH, initially absent in all patients, became positive in 10. In 7 patients, after DHECP treatment for 9 months, high definition computed tomographic scan no longer showed the focal lesions initially seen. After drug withdrawal, serum PRL increased again in all except 1 patient. Two patients had regular menses for 6 months, and 3 still had no adenoma imaged by high definition computed tomography. In BRC-treated patients the serum PRL changes and clinical results were very similar to those in the DHECP-treated patients, except for the persistence of normal serum PRL levels in 4 patients after drug withdrawal. On the other hand, side-effects were negligible during DHECP treatment, but remarkable during BRC. Systolic and diastolic blood pressures decreased by only 5.4 and 3.0 mm Hg, respectively, after acute 5 mg DHECP administration, but decreased by 12.8 and 14 mm Hg after acute 2.5 mg BRC administration. Orthostatic hypotension and peripheral vasomotor phenomena occurred in the long term DHECP treated patients except one, but they occurred in 9 and 3 of those treated with BRC, respectively. Gastric discomfort or mild nausea occurred in 12 DHECP-treated patients, while mild or severe nausea or vomiting were observed in 18, 11, and 2 of those taking BRC, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1987

Identification and the primary structure of equine alpha-lactalbumin B and C (Equus caballus, Perissodactyla).

The presence of two new alpha-lactalbumins has been demonstrated in the colostrum of a single mare (Equus caballus, Persian Arab). They have been designated equine alpha-lactalbumin B and C, and that isolated previously from the milk of Australian horses (English Thoroughbred) as alpha-lactalbumin A. The primary structures of B/C have been determined by automatic Edman degradation of enzymatic cleavage of the oxidized protein. Cyanogen bromide cleavage of S-carbamoyl-methylated protein provided necessary overlapping peptides. Comparison of the sequences of B and C with that of A indicates 3 and 4 amino-acid exchanges, respectively. The phylogenetic difference of equine alpha-lactalbumin B/C from bovine alpha-lactalbumin B is indicated by 39 and 40 amino-acid exchanges, respectively. The structure-function relationship, calcium binding sites and variants of alpha-lactalbumin are discussed.

Amino Acid Sequence↗
PubMed1987

The complete amino-acid sequence of dimeric beta-lactoglobulin from mouflon (Ovis ammon musimon) milk.

beta-Lactoglobulin from Mouflon (Ovis ammon musimon) milk has been isolated and its complete primary structure determined. This protein has been isolated in dimeric form and has a molecular mass of 37 kDa. The amino-acid sequence has been determined by microsequencing of the native protein and the peptides were obtained after tryptic cleavage. The tryptic peptides were isolated by reversed phase high-performance liquid chromatography. The primary structure of mouflon beta-lactoglobulin shows close similarity to ruminant beta-lactoglobulins. The presence of His at position 20 indicates that this protein belongs to the B-type of dimeric ovine beta-lactoglobulins. Mouflon beta-lactoglobulin is a 162 amino acid long polypeptide chain with two disulphide bridges and one free thiol group. Structural similarities to the bilin-binding protein, BG protein from olfactory epithelium and retinol-binding protein are discussed.

Amino Acid Sequence↗
PubMed1987

Role of the pineal gland in immunity: II. Melatonin enhances the antibody response via an opiatergic mechanism.

The pineal gland constitutes a major neuroendocrine organ in the brain. It transduces exogenous signals such as circadian and seasonal variations of light and temperature into proper hormonal changes which adjust and adapt internal endocrine functions. These pineal activities seem to be exerted via circadian synthesis and release of the indoleamine melatonin, a neurohormone secreted by the pineal itself. Alteration of circadian rhythms have been associated with affective disorders, psychosomatic diseases, cancer and many other pathologies. We have reported that functional and pharmacologic inhibition of melatonin synthesis results in depressed immune functions in vivo and that exogenous, evening administration of melatonin enhances antibody formation via an antigen-activated process and also antagonizes the immunosuppressive effects of corticosterone. We communicate here findings demonstrating that (a) three different inbred strains of mice possess a clear-cut cycle of melatonin levels in serum, (b) that melatonin administered in the evening enhances primary antibody response (IgM and IgG immunoglobulins) in vivo according to a dose-response behaviour and that (c) the opioid receptors blocker naltrexone antagonizes the immunostimulatory effect of melatonin. These findings point to a fundamental immunoregulatory role of circadian melatonin and to an activity of the neurohormone via opioid peptides.

Animals↗
PubMed1986

Cartilage-inducing factor-A. Apparent identity to transforming growth factor-beta.

Comparison of the sequence of the N-terminal 30 amino acids of cartilage-inducing factor-A (CIF-A) from bovine demineralized bone with the corresponding sequence of human transforming growth factor-beta (TGF-beta) revealed 100% identity. Furthermore, CIF-A stimulated normal rat kidney fibroblasts to become anchorage-independent and form colonies in soft agar (in the presence of epidermal growth factor) in a manner similar to TGF-beta. Similarly, TGF-beta from human platelets induced rat muscle mesenchymal cells to differentiate and synthesize cartilage-specific macromolecules in a manner equivalent to CIF-A. These data show that CIF-A and TGF-beta are closely related or identical molecules and that these factors may be involved in cell differentiation including cartilage formation as the first step in endochondral bone formation.

Amino Acid Sequence↗
PubMed1986

The preparation and physicochemical characterization of an injectable form of reconstituted, glutaraldehyde cross-linked, bovine corium collagen.

Pepsin-solubilized bovine corium collagen was purified, reconstituted, and treated with various levels of glutaraldehyde. Treatment of suspensions of fibrillar collagen with low concentrations of glutaraldehyde appeared to have little effect on the gross morphology of fibrils, as judged by electron microscopy, but did have a significant impact on their physicochemical stability. Fibrillar collagen treated with glutaraldehyde at a concentration equal to or greater than 0.0075% demonstrated significant decreases in neutral solubility at elevated temperatures as compared to noncross-linked controls. Differential scanning calorimetry provided a convenient and quantitative means to correlate increases in melting temperature with increases in glutaraldehyde treatment concentration. Fibrillar collagen cross-linked with glutaraldehyde concentrations as low as 0.0075% demonstrated a significantly greater resistance to proteolytic degradation than did noncross-linked fibrillar collagen samples. The residual, extractable aldehyde content of such preparations was between 1 and 3 ppm. Rheological measurements on such cross-linked suspensions demonstrated that they were non-Newtonian, shear-thinning fluids, and that they were two- to threefold more viscous than corresponding preparations of noncross-linked collagen.

Amino Acids↗
PubMed1986

Histamine release by free radicals: paracetamol-induced histamine release from rat peritoneal mast cells after in vitro activation by monooxygenase.

The incubation of paracetamol with isolated rat serosal mast cells evokes the release of histamine only in the presence of (S10) liver microsomes obtained from PCB or phenobarbital treated rats. The release of histamine was not accompanied by a leakage of lactate dehydrogenase and was blocked by the antioxidant alpha-tocopherol and by D-mannitol, an hydroxyl free radicals scavenger. The data are consistent with the metabolic oxidation of paracetamol in the generation of reactive intermediates capable of activating the sequential exocytosis.

Acetaminophen↗
PubMed1986

Role of the pineal gland in immunity. Circadian synthesis and release of melatonin modulates the antibody response and antagonizes the immunosuppressive effect of corticosterone.

Inhibition of synthesis of the pineal neurohormone melatonin (MEL) in mice, by administration of propranolol (PRO) in the evening, and daily injections of p-chlorophenylalanine (PCPA), resulted in a significant depression of the primary antibody response to sheep red blood cells (SRBC). Spleen cells from these mice showed a reduced reactivity against antigens in the autologous mixed lymphocyte reaction (AMLR). In contrast, alloreactivity remained normal. Reconstitution of the night-time peak of plasma MEL by evening injections to the mice completely reversed the suppression of the humoral response and the AMLR. MEL administration was able to antagonize the depression of antibody production induced by corticosterone in vivo. These results suggest that the pineal gland has important immunomodulatory functions through its cyclic, circadian release of MEL.

Animals↗
PubMed1986

Preparation of [3H]collagen for studies of the biologic fate of xenogenic collagen implants in vivo.

Reduction of a commercially available, pepsin-solubilized, bovine dermal collagen (Vitrogen 100) with sodium [3H]borohydride provided radiolabeled collagen preparations with specific activities ranging from 7.1-12.0 muCi/mg collagen. These specific activities were 2-3 times greater than those obtained by reduction of intact rat tail tendon collagen under similar conditions. The alpha, beta, and higher aggregate components of type I collagen were radiolabeled as well as the alpha component of a small amount of type III collagen present in the samples. Fractionation of cyanogen bromide peptides showed that alpha 1(I)CB7, alpha 1(I)CB8, and alpha 2(I)CB3,5 were the predominant peptides labeled by this procedure. Amino acid analysis indicated that the majority of the radioactivity was in reducible cross-links, precursors of these cross-links, and in hexosyllysine residues. Reconstitution experiments comparing this radiolabeled collagen with nonlabeled collagen showed them to be indistinguishable. Bacterial collagenase digestion of this reconstituted fibrillar collagen in both a lightly cross-linked (glutaraldehyde 0.0075%) and noncross-linked form provided evidence that digestion of labeled and nonlabeled collagens proceeded at similar rates. Thus, labeling did not change the properties of the collagen. Cross-linking made the preparation refractory to proteolytic degradation. Injection of fibrillar collagen preparations, spiked with radiolabeled collagen, into the guinea pig dermis followed by quantitation of the amount of radioactivity recovered from implant sites as a function of time, indicated that the lightly cross-linked samples also were more resistant to degradation in vivo than the noncross-linked preparation. The half-life of noncross-linked collagen was about 4 days while that of the cross-linked collagen was about 25 days. These degradation rates were much faster than observed for similar, nonlabeled samples injected into the dermis of humans, presumably due to a higher metabolic activity in the guinea pig dermis.

Animals↗
PubMed1986

Pig beta-lactoglobulin I (Sus scrofa domestica, Artiodactyla). The primary structure of the major component.

beta-Lactoglobulins from pooled milk (Sus scrofa domestica) are isolated and characterized. The complete primary structure of the major beta-lactoglobulin component I is presented. The amino-acid sequence was elucidated by automated Edman degradation of tryptic peptides and cyanogen bromide cleavage products in a liquid phase sequencer. The tryptic and cyanogen bromide peptides were separated by reverse-phase (RP-2) or size exclusion (TSK 2000 SW) high performance liquid chromatography. Pig beta-lactoglobulin is composed of only 159 amino acids in contrast to other beta-lactoglobulins which contain 162 or 166 amino acids. Sequence alignment with previously sequenced beta-lactoglobulins was obtained by introducing two gaps at positions 115 and 151-152. Thus bovine beta-lactoglobulin A reveals 62 amino-acid substitutions. The phylogenetic distance from horse beta-lactoglobulin I and II is indicated by 49.4% and 62% amino-acid exchanges, respectively. Pig beta-lactoglobulin is a mixture of two chains with Gln or Thr at position 119. The free thiol group is localized at position 59. The structural and functional aspects of beta-lactoglobulins and its role in vitamin A (retinol) transport are discussed.

Amino Acid Sequence↗
PubMed1986

Inhibition of lactation by a long-acting bromocriptine.

A long-acting form of bromocriptine, a prolactin (PRL) secretion inhibitor, was administered to 122 postpartum women in single intramuscular injections of 20 (N = 24), 30 (N = 22), 40 (N = 46), and 50 mg (N = 30). In 91 women the substance was administered immediately after delivery to prevent galactopoiesis and in the remaining 31 women to inhibit established lactation. Effectiveness was estimated by the absence of breast engorgement and of milk secretion. Successful prevention or inhibition of lactation was highest among women receiving 50 mg bromocriptine (97%), and comparison between dosages revealed a close linear dose-response relationship (r = 0.98). Persistent and significant (P less than .001) PRL inhibition could be recorded for up to 22 days in successfully treated puerperas in comparison with 12 normally breast-feeding women who served as control subjects. No significant side effects or local reactions were recorded. Eleven of 46 postpartum women receiving 20 or 30 mg bromocriptine experienced onset of milk secretion or lactation rebound, and responded to oral administration of the drug. The presence of milk was associated with plasma PRL concentrations persistently above 25 ng/mL in all of them, whereas nine women in the same dosage range in whom lactation suppression was effective exhibited values below this limit. Dose-response data allow the establishment of a putative PRL threshold for induction of milk secretion of about 25 ng/mL. Maintenance of plasma PRL values below this limit prevents lactogenesis and inhibits lactopoiesis.

Bromocriptine↗
PubMed1985

Hemodynamic and electrocardiographic effects of fructose-1,6-diphosphate in acute myocardial infarction.

Acute hemodynamic and electrocardiographic effects of fructose-1,6-diphosphate (FDP), an agent that is supposed to restore anaerobic glycolytic flux in the ischemic myocardium, were studied in 40 patients with acute myocardial infarction who were grouped into 4 subsets: subset 1, normal (15 mm Hg or less) pulmonary artery (PA) wedge pressure and normal (35 g-m/m2 or greater) left ventricular (LV) stroke work index; subset 2, elevated (more than 15 mm Hg) PA wedge pressure and normal LV stroke work index; subset 3, normal PA wedge pressure and reduced (less than 35 g-m/m2) LV stroke work index; subset 4, elevated PA wedge pressure and LV stroke work index moderately reduced to a range between 16 and 34 g-m/m2. Patients were randomized into an FDP (250 mg/kg body weight in isotonic saline solution intravenously in 20 minutes) and into a placebo group. Each subset contained 5 FDP- and 5 placebo-treated patients. After basal measurements, hemodynamic measurements were reassessed at 60, 90 and 120 minutes from the infusions, while a standard 12-lead electrocardiogram was recorded in the basal state and 120 minutes after infusion. Nonsignificant hemodynamic change was observed in the placebo subsets, and FDP failed to exert any effect in subsets 1, 2 and 3. A 24% (p less than 0.02) increase in cardiac index occurred 60 minutes after FDP in subset 4. LV stroke work index also increased, while PA wedge pressure remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Immunological modulation of cholinergic histamine release in isolated rat mast cells.

Isolated purified rat mast cells release histamine when exposed to acetylcholine according to different patterns of sensitivity. The degree of histamine release is correlated with the levels of reaginic antibodies presumably bound to the mast cell membrane. In fact, mast cells passively sensitized with mouse myeloma IgE against egg albumin or DNP2-lysine, react to acetylcholine with a release of histamine, which is proportional to the IgE concentration in the incubation medium. The histamine release induced by acetylcholine is due to the stimulation of a muscarinic receptor. Accordingly, acetylthiocholine is unable to evoke histamine release and preincubation of sensitized cells with atropine fully inhibits the cholinergic histamine release. The histamine release evoked by acetylcholine is potentiated by the exposure of sensitized cells to the specific antigen. The present results suggest that sensitization of mast cells is a crucial factor in modulating their sensitivity to acetylcholine.

Acetylcholine↗
PubMed1985

Hemodynamic effects of digoxin in acute myocardial infarction in man: a randomized controlled trial.

Hemodynamic effects of digoxin in acute myocardial infarction (AMI) have been acknowledged to depend on the basal cardiocirculatory state. In the present study, the effects of digoxin in patients with AMI were evaluated in four hemodynamic subsets, based on the relationship between mean pulmonary capillary wedge pressure (PCWP, in mm Hg) and left ventricular stroke work index (LVSWI, in g-m/m2): subset 1: normal (less than or equal to 15 mm Hg) PCWP and normal (greater than or equal to 35 g-m/m2) LVSWI; subset 2: elevated (greater than 15 mm Hg) PCWP and normal LVSWI; subset 3: reduced (less than 35 g-m/m2) LVSWI and normal PCWP; and subset 4: elevated PCWP and LVSWI moderately reduced to a range between 16 and 34 g-m/m2. Forty patients were admitted to the study and were randomly assigned to one of two groups in each subset: control group (19 patients) and treated group (21 patients). Five patients were randomized into each of the subsets 2, 3, and 4 in both the control and treated groups, while in subset 1 there were four control and six digoxin-treated patients. Control patients were administered a placebo saline solution and digoxin-treated patients received 0.50 mg of the drug intravenously in 20 minutes. The effects of the placebo and of the drug were evaluated at 30, 60, and 90 minutes from the end of the infusion. Hemodynamic data did not vary in the control group, and digoxin did not exert any relevant effect in subsets 1 and 2. After drug infusion, cardiac index (Cl, in L/min/m2) significantly increased in subset 3 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗