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Biomedical subjects

C Montanari

Publications and source records attributed to C Montanari.

At least 19 recordsLinked to original sources
PubMed2000

Qualitative assessment of natural apatite in vitro and in vivo.

Among the natural and synthetic materials investigated as bone graft substitutes, much interest has been focused on natural apatite obtained from low temperature heat-deproteinated compact bone. Previous research demonstrates that, when treated at a temperature below 500 degrees C, this material maintains its characteristic ultrastructural features, with a high surface/volume ratio, while as an implant material, it offers the host tissue a large surface of interaction. In vitro and in vivo tests showed that natural apatite is well tolerated and is a good osteoconducing material. The present in vivo study in rabbits was carried out to first investigate the behavior and capacity of natural apatite implants to stimulate bone ingrowth, and then to analyze the cells located at the bone/material interface. Synthetic hydroxyapatite was used as a control material. In a parallel in vitro study, we investigated the activity of differentiated osteoblasts and periosteal cells obtained from rats and new-born rabbits, incubated with natural apatite and synthetic hydroxyapatite. The in vivo study showed that natural apatite allows osteoblasts to form new bone tissue, adhering to the implant with ingrowth into the implant structure. In the presence of synthetic hydroxyapatite, a less pronounced osteoblastic activity was observed. In agreement with these observations, the in vitro study showed that natural apatite is more effective in attracting cells, favoring their proliferation and stimulating alkaline phosphatase activity. These findings suggest that natural apatite is more suitable for bone filling or bone regeneration than synthetic hydroxyapatite.

Animals↗
PubMed2000

Alveolar bone response to submerged bisphosphonate-complexed hydroxyapatite implants.

BACKGROUND: In most studies using submerged hydroxyapatite implants, maintenance of alveolar bone after tooth extraction was attempted with plain hydroxyapatite materials. However, clinical results have shown that hydroxyapatite may require biological modification with a bone resorption-inhibiting agent which may be beneficial for maintenance of alveolar bone. We conducted experimental and clinical studies to evaluate the effect of highly bisphosphonate-complexed hydroxyapatite implants on osteoconduction and repair in alveolar bone. METHODS: Porous hydroxyapatite implants were pre-incubated in 10(-2)M bisphosphonate solutions at pH 3.49. The implants had a diameter of 2.1 mm and a height of 2 mm and adsorbed 115 microg bisphosphonate. Five goats were implanted with 4 plain hydroxyapatite implants on each side of the mandible in root extraction sockets for the precision analysis of dual x-ray absorptiometry (DEXA) measurements. Ten goats were implanted with 4 bisphosphonate/hydroxyapatite implants on one side of the mandible and 4 plain hydroxyapatite implants on the opposite mandible. In a clinical study, 23 bisphosphonate/hydroxyapatite implants were placed in periodontally destroyed tooth root sockets and followed up during one year. RESULTS: The range for the bone mineral density (BMD) measurement errors for goat histologic sections was 0.48% to 1.03%. There were large differences in peri-implant BMDs in the left and right mandible of the same goat, irrespective as to whether hydroxyapatite or bisphosphonate/hydroxyapatite implants were present. This was due to local anatomical differences typical of alveolar bone. These differences were not significant. Histologically, all bisphosphonate/hydroxyapatite as well as hydroxyapatite controls appeared to be fully integrated and effective as bone replacement material in goat alveolar bone. They exhibited vascularization and osteoconduction of alveolar bone growth along and inside their porous structure. In patients peri-implant healing was clinically and radiographically comparable to plain hydroxyapatite implants. All implants were retained and no dehiscences developed. Radiographically, peri-implant radiolucencies disappeared and alveolar bone was deposited in close proximity to the implants. CONCLUSIONS: This study contributes to the understanding of the biological properties of hydroxyapatite implants as carriers for the bone-modulating agent bisphosphonate. Our study suggests that normal osteoconduction and repair occurred in alveolar bone around the highly bisphosphonate-complexed hydroxyapatite implants.

Absorptiometry, Photon↗
PubMed1997

Histological and ultrastructural evaluation of Leeds-Keio ligament six years after implant. A case report.

We examined by light and electron microscopy study a Leeds-Keio ligament removed from a patient 6 years and 4 months after implant following rupture. The new ligament presented an outer capsule made up of bundles of collagen fibres running mainly perpendicular to the long axis of the ligament. Septa were seen emerging from the capsule and composed of bundles of collagen fibres surrounding the bundles of Dacron fibres. Each thread of Dacron was surrounded by a layer of connective tissue containing periodic acid-Schiff (PAS)-positive cells. The bundles of collagen fibres making up the outer capsule, the septa and the layer of connective tissue surrounding the Dacron threads were positive for anti-type I collagen antibody. The rehabitated Leeds-Keio ligament presented a specific organization at the septa zone, showing a layer of collagen fibrils alternating with a layer of cells. Our remodelling findings suggest a shoelace effect of the artificial ligament. On the other hand, the presence of type I collagen could be responsible for the good functional behaviour of this composite system. In conclusion, the factors that play an important role in determining this remodelling process and its mechanical function are unknown.

Adult↗
PubMed1992

False aneurysm of the anterior tibial artery in lower leg fractures treated with the Ilizarov external fixator. Case report.

A case of open segmental fracture of the right lower leg treated with an Ilizarov external fixator in emergency surgery is presented. Approximately two months after operation, swelling in the anterior compartment of the tibia and repeated episodes of bleeding from one of the Kirschner wire holes led the authors to perform an angiography, which revealed the presence of a false aneurysm of the anterior tibial artery. The intraoperative finding of a double lesion in the anterior tibial artery confirmed the iatrogenous nature of the injury.

Aged↗
PubMed1989

Pharmacological characterization of mare uterus motility with special reference to calcium antagonists and beta-2-adrenergic stimulants.

1. Uterine motility was studied in vitro in the myometrial tissue obtained from pregnant and non-pregnant mares. 2. The spontaneous contractions of the preparations were not modified by tetrodotoxin, by anticholinergics, antiadrenergics, histamine H1 and H2 blockers, antiserotoninergic and opioid antagonists; but disappeared in Ca2+ and Na+ free medium. 3. beta 2-adrenergic stimulants like salbutamol and hexoprenaline and the calcium channel blockers nifedipine and verapamil were effective inhibitors of the amplitude of phasic contractions (ID50S for salbutamol and nifedipine were 7.7 nM and 14.6 nM, respectively in oestrus preparations). 4. The above data indicated that the mare myometrium contractility in vitro is very sensitive to the action of beta 2 mimetic compounds and calcium antagonists; nifedipine, in particular, seems to be a very promising alternative to beta 2 stimulants in the tocolytic therapy.

Adrenergic beta-Agonists↗
PubMed1986

Central and peripheral beta-endorphin response to transcutaneous electrical nerve stimulation.

The effects of transcutaneous electrical nerve stimulation on plasma and cerebrospinal fluid (CSF) levels of beta-Endorphin (beta-EP) were studied in 6 groups of pain-free patients. Different modes of TENS were applied for 20 minutes. Regardless of mode and/or frequency of the stimulation plasma and/or CSF beta-EP levels were significantly increased. Plasma and CSF responses were not correlated suggesting that TENS activates different opiatergic pathways at central and peripheral level.

Aged↗
PubMed1985

Antihypertensive therapy with diuretics and beta-blockers at fixed dosage: comparison between the combinations labetalol plus chlorthalidone and atenolol plus chlorthalidone.

The aim of this study was a comparison between the hypotensive effects of two fixed combinations (atenolol + chlorthalidone and labetalol + chlorthalidone) in patients suffering from untreated mild to moderate hypertension. Both combinations were effective in reduction of BP values. Heart rate showed no statistically significant modification. The combination of labetalol plus chlorthalidone seems to find its best application in the treatment of mild hypertension.

Adrenergic beta-Antagonists↗
PubMed1983

An overview of international clinical trials with halometasone cream.

In international multicentre comparative clinical trials carried out by dermatologists in 717 patients with non-infected acute eczematous dermatoses at 28 trial centres in Austria, Germany, Holland, Switzerland and Yugoslavia, halometasone cream exhibited a very satisfactory therapeutic effect in acute contact dermatitis, atopic dermatitis, nummular dermatitis and seborrhoeic dermatitis. It yielded 'good' to 'very good' results in 89.7% of the 333 patients treated with halometasone cream. Halometasone cream was significantly more effective than Diproderm, Diprosone and Ultralan creams with respect to the overall success rate, the percentage of patients with 'very good' results and early cures. It proved marginally superior to Halciderm cream in therapeutic efficacy. The onset of therapeutic effect was more rapid in patients treated with halometasone cream than in those on treatment with comparative preparations. Halometasone cream was well tolerated and neither skin atrophy nor any systemic effect due to the transcutaneous systemic absorption of the corticoid was observed. In view of the rapid onset of action, very good efficacy and tolerability, halometasone cream, with agreeable cosmetic and applicatory properties, may be considered as a suitable corticosteroid topical for the treatment of acute eczematous and other corticosteroid-responsive dermatoses.

Administration, Topical↗
PubMed1983

An overview of international clinical trials with halometasone ointment in chronic eczematous dermatoses.

Four international, multicentre, comparative clinical trials were carried out by twenty-two dermatologists in 569 patients with non-infected chronic eczematous dermatoses in Austria, Germany, Spain, Switzerland and Yugoslavia. In these clinical trials halometasone ointment exhibited a very satisfactory therapeutic effect in all the five types of non-infected chronic eczematous dermatitis, namely chronic contact dermatitis, atopic dermatitis, lichen simplex chronicus, seborrhoeic dermatitis and nummular dermatitis. It yielded an overall success rate ('good' to 'very good' results) of 85% as against 71% obtained with the comparative preparations. With regard to therapeutic effect, halometasone ointment proved significantly superior (p = 0.0001) to Ultralan ointment but it was less effective than Dermovate ointment (p = 0.052). It yielded overall success rates higher than those obtained with Diproderm (84.6% versus 74.4%) and Synalar (88.5% versus 72%) ointments. Halometasone ointment was well tolerated and neither skin atrophy nor any systemic effect due to the transcutaneous systemic absorption of the corticoid was observed.

Administration, Topical↗
PubMed1981

[Systolic times adjustment during pregnancy and puerperium (author's transl)].

During pregnancy and the post partum period important cardiovascular adjustments take place, which for ethical views need a non invasive approach. In the present work we studied the alterations of the Systolic Time Intervals in both supine and lateral decubitus during each trimester and at the fifth day and fifth week after delivery. In the first part of pregnancy a significant reduction of the preejection time (PE) and PE/EVS with an increase of the left ventricular ejection time (EVS) become evident. In the second part the picture reverses to a significantly reduced EVS and increased PE and PE/EVS. This picture even if decreasing, is present in the post partum period. The first part of pregnancy is characterized by a hyperkinetic condition; in the second one the position of the woman becomes important, and the reduction of the EVS is at least partially due to an impaired venous return (compression of the vena cava by the gravid uterus). The persistence of altered systolic time intervals in the post partum (increased PE/EVS) suggest an impaired myocardial performance.

Adult↗