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Biomedical subjects

A Conti

Publications and source records attributed to A Conti.

At least 217 records · Page 12Linked to original sources
PubMed1988

The influence of heparin on the wound healing response to collagen implants in vivo.

The biologic response to fibrillar collagen (collagen) and fibrillar collagen plus heparin (collagen/heparin) implants have been compared in the rat subcutaneous and guinea pig dermal wound models. The reconstituted bovine dermal collagen implants were injected subcutaneously in rats at concentrations ranging from 18 to 30 mg/ml and in volumes ranging from 0.5 to 1.0 ml. The biologic response to the collagen implants alone was characterized by a transient invasion of a modest number of inflammatory cells within the first three days of implantation that was followed by limited fibroblast invasion into the peripheral 1/3 of the implant during the course of the next three to four weeks. Occasionally, blood vessels were observed to invade the peripheral regions of the implant. The degree (number) and extent (depth) of cell invasion were inversely related to initial collagen implant concentration. Addition of heparin (0.3-20 micrograms/mg collagen) to these implants resulted in a significant dose-dependent increase in the degree and extent of fibroblast invasion. Radiolabeling studies showed that the collagen and collagen/heparin implants were cleared from the subcutis at identical rates. Implantation of these formulations in a guinea pig dermal wound model was also performed, using a semi-occlusive wound dressing (Opsite) to maintain the implant in the wound site. The fibrillar collagen implant alone was pushed upward by developing granulation tissue at the base of the wound and served as a support for epidermal cell migration, proliferation, and differentiation as wound closure proceeded. The implant was slowly invaded and turned over as granulation tissue developed from the base and margins of the wound bed. The inclusion of heparin in these implants resulted in a significantly different pattern of wound healing. The collagen/heparin implants histologically presented a more broken-up or porous appearance following implantation, which was associated with a greater degree of penetration of developing granulation tissue into the implant itself as compared to the collagen implants. Radiolabeling studies revealed that clearance rates of implants with and without heparin from wound sites were similar, as noted in the rat subcutis. Laser doppler flowmetry studies suggested that the heparin--containing implants were more vascular than control wound sites or sites treated with collagen alone.

Animals↗
PubMed1988

Microanalysis of the amino-acid sequence of monomeric beta-lactoglobulin I from donkey (Equus asinus) milk. The primary structure and its homology with a superfamily of hydrophobic molecule transporters.

The complete primary structure of donkey beta-lactoglobulin I was determined by pulsed-liquid phase microsequencing of tryptic peptides. The protein has been isolated in monomeric form and it corresponds to monomeric beta-lactoglobulin of type I. With the inclusion of donkey beta-lactoglobulin I there are 13% common residues amongst the members of the beta-lactoglobulin family. Donkey beta-lactoglobulin I is homologous to the retinol-binding protein, bilin-binding protein and five other proteins belonging to the new superfamily of hydrophobic molecule transporters. A rapid method for peptide isolation and the strategy for microsequencing of this protein have been described.

Amino Acid Sequence↗
PubMed1988

The primary structure of donkey (Equus asinus) lysozyme contains the Ca(II) binding site of alpha-lactalbumin.

The complete primary structure of donkey lysozyme has been established by pulsed liquid-phase sequencing of tryptic and chymotryptic peptides isolated by RP-HPLC. The positions of the Cys residues were identified by labeling the Cys residues with DABIA-reagent. Donkey lysozyme is a c-type lysozyme which is 129 amino acids long. It exhibits 50% homology to the human protein. We observe the full Ca(II) binding site suggested for the homologous alpha-lactalbumines. Although horse lysozyme has been reported to contain asparagine in position 61, which was in conflict with the three-dimensional structure of lysozyme, all other known c-type lysozymes, including donkey, contain Ser 61.

Amino Acid Sequence↗
PubMed1988

[Significance of QT interval as a premonitory sign of severe ventricular arrhythmia in the early phase of myocardial infarct].

In order to evaluate the relationship between the length of the corrected QT interval (QTc), calculated according to Bazett's formula, and the incidence of ventricular fibrillation (V.F.) in the early phase of acute myocardial infarction (A.M.I.), the QTc interval was measured in 494 patients (mean age 66.42 +/- 11 years; 357 males and 137 females) assisted by the Mobile Coronary Care Unit of Florence. A.M.I. was anterior in 269 patients, inferior in 177 and non-Q in 34. The QTc interval measured on E.C.G. was recorded within the first hour after the onset of pain in 203 patients and between the first and sixth hour in 291 patients. The QTc interval was also measured in a control group consisting of 96 non A.M.I. patients with no history of coronary artery disease. 43 patients with A.M.I. (8.6%) developed V.F. in the first 24 hours. It was observed that: 1) The QTc interval of patients with A.M.I. was longer than that in patients without A.M.I. (432 +/- 34.18 msec. versus 425.37 +/- 25, p less than 0.02). 2) The QTc interval of patients with A.M.I. who developed V.F. was the same as that of patients with A.M.I. but without V.F., (432.6 +/- 34.18 msec. versus 438.11 +/- 34.13, N.S.). 3) 60.46% of patients with V.F. had a value of QTc less than 440 msec.; the incidence of QTc greater than 440 msec. showed no difference in the groups with or without V.F. (41.86% versus 41.11%). 4) The QTc interval length was greater in anterior than in inferior A.M.I. (435.12 +/- 30.81 msec. versus 429.05 +/- 34.5, p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Role of the pineal gland in immunity. III. Melatonin antagonizes the immunosuppressive effect of acute stress via an opiatergic mechanism.

We have recently demonstrated that the pineal neurohormone melatonin exerts important immunoregulatory functions. We now report that exogenous melatonin counteracts completely the effect of acute anxiety-restraint stress on thymus weight and antibody response to sheep red blood cells (SRBC). In addition, administration of melatonin in the evening prevented paralysis and death of mice infected with sublethal doses of encephalomyocarditis virus (EMCV) after acute stress. The anti-stress activity of melatonin was present in mice injected with T-dependent antigens, and it was abolished by the contemporary administration of the specific opioid-antagonist naltrexone. This suggests that melatonin exerts its remarkable anti-stress effect on antigen-activated cells via an opiatergic mechanism. These findings have important implications at both basic and clinical levels. They provide a new approach to a possible physiological 'up-regulation' of the immune response under virus- and/or stress-related immunosuppression.

Acute Disease↗
PubMed1987

Vasoactive intestinal polypeptide and dopamine: effect on prolactin secretion in normal women and patients with microprolactinomas.

In order to investigate the influence of dopamine (DA) in modulating prolactin (PRL) response to vasoactive intestinal polypeptide (VIP), VIP (75 micrograms i.v. over 12 min) was administered to normal women and patients with microprolactinomas during saline or DA (0.06 micrograms/kg BW/min) infusion. In 8 normal women VIP caused PRL to rise from 7.9 +/- 0.8 (mean +/- SE) to 33.4 +/- 17.1 ng/ml (p less than 0.01), the peak occurring at 15 min, while it did not elicit any significant modification in serum PRL levels in 18 patients with microprolactinomas. DA infusion lowered serum PRL by 67 and 58.2% at 120 min in normal women and in patients with microprolactinomas, respectively, and abolished VIP-induced PRL response in normal women without influencing PRL response in patients with microprolactinomas. PRL responsiveness to VIP was not restored by dopaminergic disinhibition (domperidone 10 mg i.v.) in 4 patients tested. Two previously unresponsive patients showed a VIP-induced PRL increase, superimposable on that recorded in normal women, after successful selective adenomectomy. These data suggest that DA, although able to suppress VIP-induced PRL response in normals, does not play any major role in causing unresponsiveness to VIP in prolactinomas. The lack of PRL responsiveness to VIP might be intrinsic to the adenoma or due to alterations of PRL secretion regulatory mechanisms other than DA secondary to the presence of the tumor, or to a depletion of the readily releasable pool of PRL.

Adolescent↗
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↗