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Biomedical subjects

G Leoni

Publications and source records attributed to G Leoni.

At least 37 records · Page 2Linked to original sources
PubMed1997

Long-term haemodynamic and antiarrhythmic benefits of DDIR versus DDI pacing mode in sick sinus syndrome and chronotropic incompetence.

AIMS: The aim of this Italian multicentre study was to evaluate the haemodynamic and antiarrhythmic effects of DDIR versus DDI pacing mode in sick sinus syndrome with chronotropic incompetence. METHODS: Seventy-nine patients were implanted with a dual chamber rate-responsive pacemaker (Medtronic 7075) and centrally randomised to DDI or DDIR pacing mode. After six months, the pacing modality was crossed over. Follow-up included clinical data, rest ECG, echocardiography, Holter monitoring and exercise testing in DDIR. RESULTS: a) Haemodynamic effects. Comparing postimplant exercise testing in DDIR mode with preimplant tests, peak heart rate increased from 96 +/- 17 to 115 +/- 17 bpm (+20%, p < 0.0001), total work capacity from 7.0 +/- 3.5 to 8.8 +/- 4.3 minutes (+26%, p < 0.0001), peak oxygen uptake from 1238 +/- 406 to 1453 +/- 423 ml/min (+17%, p < 0.001) and oxygen uptake at anaerobic threshold from 977 +/- 343 to 1222 +/- 415 ml/min (+25%, p < 0.001). These benefits persisted unchanged during one-year follow-up. b) Antiarrhythmic effects. After six months, paroxysmal atrial fibrillation recurrence significantly decreased in the whole population: group I (DDI) 20.7 vs 48.3%, p < 0.02; group II (DDIR) 21.2 vs 36.4%, p < 0.05; group I + II (DDI + DDIR) 21.0 vs 41.9%, p < 0.001. After one year no significant differences were found between DDI and DDIR. Group I: DDI 23.8 vs DDIR 28.6%, ns; group II: DDI 22.7 vs DDIR 18.2%, ns. CONCLUSION: DDIR vs DDI significantly improves short- and long-term haemodynamic performance. Dual chamber pacing shows a significant reduction of paroxysmal atrial fibrillation recurrence, regardless of rate responsiveness.

Aged↗
PubMed1996

Effect of biopsy and vitrification on in vitro survival of ovine embryos at different stages of development.

The objective of the present study was to assess the in vitro viability of ovine embryos at different stages of development after combining cell sampling and vitrification. Precompacted morulae, compacted morulae and blastocysts were obtained from superovulated Sarda ewes at 4, 5 or 6 d following insemination. Embryo cell biopsy was carried out in a 100-microl drop of PBS + 10% fetal calf serum (FCS) with 10 micromol nocodazole and 7.5 microg/ml cytochalasin-b by aspiration (3-5 cells). Embryos were cryopreserved at room temperature after exposure of 2 solutions for 5 min, transferred into a vitrification solution, loaded into the center of 0.25-ml straws separated by air bubbles from 2 columns of sucrose 0.5 M and plunged immediately into liquid nitrogen. In Experiment 1, the in vitro viability of manipulated or vitrified embryos after in vitro co-culture in TCM 199 medium with 10% FCS and sheep oviductal epithelial cells (SOEC) in 5% CO2 humidified atmosphere in air at 39 degrees C was significantly lower (P < 0.05 and P < 0.01, respectively) at precompacted morula (60 and 30%) and compacted morula (62 and 39%) stages than intact embryos at the same stages (87 and 88%). No differences were found at the blastocyst stage. In Experiment 2, the in vitro survival rate of precompacted morulae which were manipulated and immediately vitrified was lower (P < 0.05) than in those manipulated and, after a temporary period of culture, vitrified at blastocyst stage (21 vs 48%); while no differences were found at compacted morula and blastocyst stages. The results show that 1) the stage of development influences the subsequent in vitro viability of manipulated and vitrified ovine embryos, 2) temporary culture after manipulation and before vitrification improves the in vitro viability of embryos, and 3) the hole in the zona pellucida resulting from biopsy does not affect blastocyst survival after subsequent vitrification.

Journal Article↗
PubMed1995

Analysis of linkage disequilibrium between different cystic fibrosis mutations and three intragenic microsatellites in the Italian population.

Three intragenic microsatellites of the CFTR gene, a TA and a CA repeats, namely IVS17bTA and IVS17bCA, located in intron 17b and a CA repeat (IVS8CA) located in intron 8 of the CFTR gene, were analyzed in a large sample of Italian cystic fibrosis (CF) and normal chromosomes. Linkage disequilibrium was evaluated between each marker and difference CF mutations on a total of 377 CF and 358 normal chromosomes. Our results are consistent with the hypothesis that all delta F508 chromosomes derive from a single mutational event. The same hypothesis is valid for mutations G542X, N1303K, 1717-1G-->A, which might have been originated more recently than delta F508.

Cystic Fibrosis↗
PubMed1995

Two culture systems showing a biphasic effect on ovine embryo development from the 1-2 cell stage to hatched blastocysts.

This study compared the effect of using either CZB or TCM 199 media on both the development of 1-2 cell ovine embryos from superovulated ewes to the blastocyst stage (Experiment 1), and the hatching process of ovine blastocysts developed in vitro (Experiment 2). For the first 5 d, the CZB medium showed higher rates of embryo development than the TCM 199 medium (p < 0.001). The embryos reaching the > 16 cell stage were 79 vs 52% and 74 vs 20% with or without an oviductal monolayer, respectively, and those reaching the blastocyst stage were 71 vs 46% and 46 vs 13% with or without cells. The CZB medium was less able to support the hatching process of the blastocysts obtained in the first experiment than was the TCM-199 medium + 10% FCS (fetal calf serum) with cells (31 vs 92%; p < 0.001) or without cells (13 vs 66%; p < 0.001). No blastocysts completely escaped from the zona pellucida (ZP) in the CZB medium compared with 80 and 61% in the TCM 199 medium with or without cells, respectively. In Experiment 3, 47% of the blastocysts migrated through the artificial opening of the ZP and hatched completely. After 24 h of culture in the CZB medium, however, they showed blastocoelic cavity breakdown. During the preliminary cleavages, the ovine embryos developed better in CZB medium than in TCM 199, but the latter was more efficient in promoting the hatching process of the blastocysts.

Animals↗
PubMed1992

Conservative and surgical treatment in acute and chronic anal fissure. A study on 308 patients.

The aetiology of anal fissure is not fully understood--why some heal spontaneously and others become chronic remains a mystery. In this study we compared surgical and conservative therapy and investigated which surgical procedure is most useful in the treatment of fissure. There were investigated 308 patients, 157 with acute fissure and 151 with chronic fissure. Healing was achieved in 45 +/- 15 days and in 40 +/- 10 days in acute fissures treated conservatively and surgically, respectively, 40 +/- 15 days and 30 +/- 5 days were required to achieve healing in chronic fissure by conservative and surgical therapy, respectively. Manometric tests showed a decrease in resting pressure and maximum voluntary contraction pressure at one month, and an increase towards the pre-operative level at 4 months for both parameters. There were no recurrences at 5 years in 100 patients (50 males and 50 females).

Acute Disease↗
PubMed1991

[Picotamide: use in chronic obliterative arteriopathies of the lower limbs].

In the present study the authors evaluated treatment efficiency and patient compliance of medium-term therapy with Picotamide, given in doses of 900 mg/die for the first 15 days, and 600 mg/die up to the completion of a three-month period, to 50 patients affected by vaso-occlusive arterial disease of the lower limbs. At follow-up visits the following controls have been carried out: CW Doppler sonography of the lower limbs, Maximum Walking Distance (M.W.D.), Red blood cell count, White blood cell count, Platelet count, Haemoglobin and Fibrinogen levels. At the end of the three-month therapy period the Ankle-Arm parameters remained unchanged.

Aged↗
PubMed1991

Study of laser damage to injection-molded diffractive intraocular lenses.

A study of the probability of damage induced in two implant quality injection-molded diffractive intraocular lenses by a commercial Q-switched Nd:YAG laser is presented. The damage thresholds of the diffractive intraocular lenses (0.10 mJ at 10% probability, 0.24 mJ at 50% probability, and 0.90 mJ at 99% probability) did not differ significantly from those of other poly(methyl methacrylate) lenses manufactured with the same technology. These low values (compared to those of other lens types) suggest that care should be taken during laser capsulotomy in eyes implanted with refractive lenses, with special attention given to power losses at the target site due to diffraction effects.

Laser Therapy↗
PubMed1991

Histopathology of continuous wave neodymium: yttrium aluminum garnet and diode laser contact transscleral lesions in rabbit ciliary body. A comparative study.

Neodymium: yttrium aluminum garnet (Nd:YAG) laser transscleral cyclophotocoagulation has been shown to be an effective method of lowering intraocular pressure (IOP). Transmission and absorption features of diode laser radiation (810 nm) make these new laser sources suitable for production of transscleral thermal lesions. The transscleral effects on rabbit ciliary body of Nd:YAG and diode laser wavelengths were compared using a CW Nd:YAG laser and a CW Aluminum Gallium Arsenide diode laser. Both lasers were delivered by silica optic fibers, 600 microns in diameter. Eight rabbits were treated by applying the optic fiber 0.5 mm from limbus while increasing energy values from 0.2-2 J. The lesions produced at equal energy values underwent gross and histologic and ultrastructural comparison. Gross examination revealed threshold lesions at 1 J energy for the Nd:YAG laser and 0.8 J for the diode laser. The diode laser produced transscleral thermal lesions of the rabbit ciliary body comparable to those achieved by the Nd:YAG laser. The histologic and ultrastructural study showed that diode laser radiation produced more remarkable damage to the ciliary pigmented structures, causing deep coagulation necrosis of the pigmented epithelium, wide disorganization of the collagen in the stroma, and intravascular coagulation phenomena in the ciliary vessels. Before the introduction of these new laser sources in clinical transscleral procedures, further investigation is needed to determine optimal energy levels.

Animals↗
PubMed1990

Probe placement and energy levels in continuous wave neodymium-YAG contact transscleral cyclophotocoagulation.

To improve the reliability of the technique, contact transscleral cyclophotocoagulation was performed using a continuous wave neodymium-YAG laser. Radiation was delivered via a fiberoptic system to two human eyes destined for enucleation due to choroidal melanoma. Distances from the corneal limbus to where the fiberoptic probe was placed, perpendicular to the conjunctiva, were varied, as were the energy values. Gross, light microscopic, and scanning electron microscopic examinations revealed that contact probe placement at a distance of 1.5 mm from the corneal limbus with an energy setting of 2 J provided optimum cyclophodestructive results. Slight superficial damage to the sclera was detected, but observations indicated no alterations to the adjacent anatomical structures. To obtain lesions to the ciliary processes in living eyes similar to those previously noted in human cadavers, comparatively lower energy values (2 J) were required. To exploit all the mechanisms that may lead to a decrease in intraocular pressure, precise hitting of the aqueous humor secretory structure may prove to be of primary importance.

Choroid Neoplasms↗
PubMed1990

Comprehensive study of damage to intraocular lenses by single and multiple nanosecond neodymium: YAG laser pulses.

The results of an extensive study of the probability of damage induced in implant quality intraocular lenses (IOLs) by a commercially available nanosecond Nd:YAG photodisruptor are presented. These results were compared with the morphology of damage seen on scanning electron microscopy. The differences in the shape of the damage probability curves derived for the different lens groups demonstrate that a single threshold value does not characterize the threshold for IOL damage. We suggest that a standard method using a clinical photodisruptor be used by all workers to derive these curves for all IOLs in clinical use. The clinical relevance of our findings is emphasized.

Lasers↗
PubMed1990

Regional distribution of cystic fibrosis linked DNA haplotypes in Italy, a collaborative study.

In view of the reported variations of cystic fibrosis (CF) associated haplotypes among populations, a detailed analysis of the distribution of two tightly linked DNA markers (Xv-2c and KM.19) in 18 Italian regions was performed. Haplotypes were determined for 405 CF chromosomes carrying the mutation, and showed significant heterogeneity between the North, Center, and South of Italy and the island of Sardinia. KM.19/PstI Restriction Fragment Length Polymorphism (RFLP) showed significant heterogeneity in these four areas, and was statistically correlated with the geographic distribution of the disease, while Xv-2c/TaqI polymorphism, like the haplotypes of normal chromosomes, was more uniformly distributed over the same four areas. Correlation coefficients between the markers and the mutation have been used to obtain additional indications on the physical distance between the markers and the fibrosis locus.

Cystic Fibrosis↗
PubMed1989

Contact transscleral irradiation of the human chorioretina with continuous-wave Nd:YAG laser.

We performed contact transscleral chorioretinal photocoagulations with a continuous-wave Nd:YAG laser on two human eyes affected by choroidal melanomas. An optical-fiber system without any focalization tip was used to deliver the laser energy by placing the fiber in contact with the sclera in the position corresponding to the chorioretinal area to be photocoagulated. With a power of 4 W and an exposure time of 0.5 s, frank white coagulations were obtained. Histological and ultrastructural examination evidenced that the choroidal pigment and the retinal pigment epithelium were the target structures of the radiation. No substantial alterations of the sclera were noted while a good adhesion between the retina and the pigment epithelium cells was observed. The results obtained show that transscleral contact lasers may be safely used in the treatment of some pathologies of the ocular fundus.

Choroid↗
PubMed1989

[Uterine hypoplasia and infertility].

On the basis of reported data, uterine hypoplasia is analysed from the morphological as well as the functional viewpoint (myo-endometrial receptivity and reactivity and ovarian vascularisation) through the routine use of two new methods of diagnosis: laparoscopy and hysteroscopy. Following the study of the relations between uterine hypoplasia and infertility, it is concluded that a precise therapeutic protocol should be laid down after correct diagnostic procedure.

Female↗
PubMed1989

Histopathology of diode and argon laser lesions in rabbit retina. A comparative study.

Argon lasers are the most frequently used laser source for retinal photocoagulation. These are expensive, bulky and low-efficiency devices. In contrast, diode semiconductor lasers have a number of characteristics that make them attractive for medical application: compact size, high electrical-to-optical efficiency, and long operating lifetime. Comparable irradiance lesions (about 120 Wcm2), ophthalmoscopically similar to those obtained therapeutically in humans, were obtained by a diode and an argon laser. Twenty-four hours after the treatment, a study of these lesions was made by light and electron microscopy. Argon irradiations resulted in damage to both the inner and the outer retinal layers, while the diode laser radiation produced damage to the outer retina and choroid. A sufficient diode laser light passed into the choroid to induce small vessel occlusions and/or edema. The histological characteristics of the lesions produced by the two lasers suggest the use of the diode lasers, as well as argon lasers, in the treatment of retinal and subretinal pathologies.

Animals↗
PubMed1988

Complications of argon laser retinal buckling performed in myopic subjects presenting rhegmatogenous degenerations.

Twenty-two eyes of twenty-two patients suffering from retinal peripheral degenerations underwent preventive equatorial buckling with argon laser photocoagulation. The fellow eye was used as control. We evaluated the effects of laser photocoagulation on corneal sensitivity, on accommodation, on pupillary diameter and light reflex. In the postoperative period, up to the 3rd month, results were significant with respect to the control eye. The mechanisms to which the onset of these undesired alterations is due are discussed.

Accommodation, Ocular↗