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V Ventura

Publications and source records attributed to V Ventura.

17 recordsLinked to original sources
PubMed2001

A spike-train probability model.

Poisson processes usually provide adequate descriptions of the irregularity in neuron spike times after pooling the data across large numbers of trials, as is done in constructing the peristimulus time histogram. When probabilities are needed to describe the behavior of neurons within individual trials, however, Poisson process models are often inadequate. In principle, an explicit formula gives the probability density of a single spike train in great generality, but without additional assumptions, the firing-rate intensity function appearing in that formula cannot be estimated. We propose a simple solution to this problem, which is to assume that the time at which a neuron fires is determined probabilistically by, and only by, two quantities: the experimental clock time and the elapsed time since the previous spike. We show that this model can be fitted with standard methods and software and that it may used successfully to fit neuronal data.

Animals↗
PubMed2000

Neuronal activity in macaque supplementary eye field during planning of saccades in response to pattern and spatial cues.

The aim of this study was to determine whether neuronal activity in the macaque supplementary eye field (SEF) is influenced by the rule used for saccadic target selection. Two monkeys were trained to perform a variant of the memory-guided saccade task in which any of four visible dots (rightward, upward, leftward, and downward) could be the target. On each trial, the cue identifying the target was either a spot flashed in superimposition on the target (spatial condition) or a foveally presented digitized image associated with the target (pattern condition). Trials conforming to the two conditions were interleaved randomly. On recording from 439 SEF neurons, we found that two aspects of neuronal activity were influenced by the nature of the cue. 1) Activity reflecting the direction of the impending response developed more rapidly following spatial than following pattern cues. 2) Activity throughout the delay period tended to be higher following pattern than following spatial cues. We consider these findings in relation to the possible involvement of the SEF in processes underlying attention, arousal, response-selection, and motor preparation.

Analysis of Variance↗
PubMed1998

Bleeding patterns in recent postmenopausal outpatients with uterine myomas: comparison between two regimens of HRT.

OBJECTIVES: To evaluate and to compare the bleeding patterns obtained with two regimens of hormone replacement therapy given to early postmenopausal women with asymptomatic uterine leiomyomas. METHODS: In this randomised prospective 1-year study 50 early postmenopausal women with one to four asymptomatic uterine leiomyomas were enrolled into two study-groups to take two regimens of hormone replacement therapy for 12 28-day cycles: (A) Tibolone, 2.5 mg/day; (B) conjugated equine estrogens (CEE), 0.625 mg/day plus medroxyprogesterone acetate (MPA), 5 mg/day. The bleeding patterns and the changes in uterine volume of the 47 outpatients who completed the study were evaluated and compared. RESULTS: Amenorrhea incidence was higher in group A (75.0% of the cycles) than in group B (65.6% of the cycles), while irregular bleeding and irregular spotting incidences were higher in group B (29.7 and 4.7% of the cycles, respectively) compared to group A (22.6 and 2.4% of the cycles, respectively). The mean bleeding and spotting lengths were not statistically different between patients in group A and those in group B. Finally, at the end of the study period transvaginal ultrasonography showed no significant change in leiomyoma size. CONCLUSIONS: The results demonstrate that, in early postmenopausal patients with asymptomatic uterine leiomyomas, Tibolone treatment seems to be preferable compared to CEE-MPA continuous combined treatment in relation to the lesser occurrence of irregular bleeding. Furthermore, neither Tibolone nor CEE-MPA therapy, at the doses used here, promote fibroid growth.

Anabolic Agents↗
PubMed1998

[Postmenopausal osteoporosis in the Emilia-Romagna region. Extent of the problem].

BACKGROUND: The purposes of this paper are to summarise the epidemiological data concerning the frequency of postmenopausal osteoporosis and its related fractures in Emilia-Romagna, a province of northern Italy, and to determine the future impact of this disease. METHODS: To evaluate how many people suffer from postmenopausal osteoporosis it was decided to calculate the number of hospital admissions due to this disease or to its related fractures in postmenopausal women--included and excluded according to the ICD9-CM codes relative to the hospital discharges--during the years 1994 and 1995. RESULTS: The results show that incidence rates of these hospital admissions increase with age, as well as the number of osteoporotic fractures. Hip fractures, which represent a major problem due to their costs and consequences, are the more frequent osteoporotic fractures which need hospital admission, while it is possible that a large part of other fractures (which do not need hospitalisation or have been treated in private structures) has not been calculated. CONCLUSIONS: When projected to the population of women living in Emilia-Romagna in the future decade, also keeping the age-specific fracture rates constant, these data suggest that the occurrence of postmenopausal osteoporosis and of osteoporotic fractures will increase, with a dramatic escalation of economic and human costs. Finally, direct costs related to postmenopausal osteoporosis have been calculated for the decade 1995-2004.

Aged↗
PubMed1997

Three-year longitudinal study with quantitative ultrasound at the hand phalanx in a female population.

A longitudinal study was conducted to assess the value of quantitative ultrasound (QUS) measurement in predicting the risk of fracture and to evaluate how QUS parameters change with ageing and the climacteric. A group of 211 female subjects underwent assessment by QUS at the distal metaphysis of the first phalanx of the last four fingers of the hand on two occasions 3 years apart. The subjects were selected from outpatients attending the orthopaedic clinic, provided they were not affected by metabolic disease or under treatment with drugs known to interfere with bone metabolism. In vivo the coefficient of variation and the standardized coefficient of variation of the QUS device were respectively 0.5% and 3.5%. The correlation between the values of the amplitude-dependent speed of sound (AD-SoS) in the two measurements was r = 0.92. In 77.3% of the subjects during the observation period we recorded a reduction in AD-SoS. During the study 22 fractures were observed in peripheral sites, 8 of which were associated with 'low-energy trauma'. By multiple logistic regression analysis we found that the relative risk of fracture for a 1 SD reduction in AD-SoS was 1.5 (95% CI 1.1-1.7) (p < 0.03). The percentage of low-energy fractures significantly increased among those subjects with an AD-SoS value lower than 1850 m/s (T-score < -3.5) at the first examination (p <0.0001). QUS investigation proved to be especially sensitive to hormonal changes associated with the climacteric: we observed a mean decrease of 56 m/s in the AD-SoS for women who entered the menopause between the first and the second QUS test (average time since menopause 2 years), as against 10 m/s in subjects remaining premenopausal. In a group of 146 subjects with 'normal' Ad-SoS at the first examination, we observed a significant reduction in AD-SoS only after 40 years of age. This study demonstrates that measurement of the AD-SoS at the phalanx is reproducible, can be employed to assess the risk of fracture, and is able to detect age-related alterations in bone tissue.

Adult↗
PubMed1997

Bone effects of transdermal hormone replacement therapy in postmenopausal women as evaluated by means of ultrasound: an open one-year prospective study.

OBJECTIVES: To evaluate the effectiveness of transdermal oestrogen replacement therapy plus medrogestone (HRT) in postmenopausal bone loss prevention by means of US. METHODS: We enrolled 112 healthy postmenopausal women in an open, prospective study. These women, after a gynaecological evaluation and an US assessment of the skeletal status, were advised to take cyclic sequential oestrogen/progestagen therapy: 50 microg/day of transdermal 17beta-oestradiol (Rotta Research Laboratorium) plus 5 mg/day of medrogestone, for 12 days per cycle (Wyeth-Ayerst). After 1 year we recalled these women: only 32 of them were taking HRT, while 49 had declined HRT without taking alternative therapies. The remaining women were excluded from the study as they were either unavailable for the check-up or they were taking prohibited therapies. We used DBM Sonic 1200 (Igea, Italy) to assess US parameter changes at phalanxes at enrollment and after 1 year. This device enabled us to evaluate US transmission velocity (AD-SoS) and US attenuation pattern (UBPS). In a previous study we had evaluated the intra- and inter-observer reproducibility of AD-SoS measurements (0.4 and 1.0% respectively). Using the same data we evaluated the intra- and inter-observer precision of UBPS. RESULTS: The UBPS intra-operator reproducibilities were 5.3% and 6.1% (for the 1st and the 2nd operator, respectively), while inter-observer precision was 8.8%. Both AD-SoS and UBPS significantly decreased in the non-user group(-0.7%, P < 0.001 and -14.3%, P < 0.001 respectively). In the user group AD-SoS showed a significant increase (+0.7%, P < 0.01), while a slight but significant decrease was observed for UBPS (-2.8%, P < 0.05). CONCLUSIONS: Our findings show that the effectiveness of transdermal HRT in slowing or even arresting postmenopausal bone loss can be monitored by quantitative US studies. The trend difference observed between AD-SoS and UBPS with and without therapy is at least partially explained by a different response to HRT with regard to bone density as well as structure.

Administration, Cutaneous↗
PubMed1997

Bone density changes in postmenopausal women with the administration of ipriflavone alone or in association with low-dose ERT.

Ipriflavone is a synthetic flavonoid that has been shown to exert a direct inhibitory effect on osteoclastic activity and possibly stimulate the osteoblast activity in different experimental models. The aim of the present study was to evaluate the effects of either ipriflavone alone or ipriflavone plus low dose hormone replacement therapy (HRT) in the prevention of postmenopausal bone loss. Patients were randomly allocated to different treatment groups receiving calcium (500 mg/day, control group), continuous HRT (25 or 50 micrograms/day of transdermal 17 beta-estradiol) plus medrogestone 5 mg/day for 12 days/month, ipriflavone at the standard dose of 600 mg/day, or finally ipriflavone 600 mg/day plus 17 beta-estradiol 25 micrograms/day plus medrogestone 5 mg/day for 12 days/month. No significant differences in basal levels of biochemical markers of bone turnover or in basal bone mineral density (BMD) values were evident in the different groups. In the control group after 12 months, spine BMD showed a significant (p < 0.05) 3.41% decrease. The pattern of BMD modification was significantly different from controls in the high dose HRT group (+1.84%), the ipriflavone group (+0.11%), and the combined ipriflavone/HRT group (-0.22%). Conversely, the BMD pattern in the low dose HRT group (-0.55%) was similar to that observed in controls. Thus, present results confirm that ipriflavone and 50 micrograms/day of transdermal 17 beta-estradiol are effective measures in the prevention of postmenopausal osteopenia. A lower transdermal estrogen dose is unable to increase the antiresorptive effect of ipriflavone and did not exert any further action in the prevention of postmenopausal osteopenia.

Administration, Cutaneous↗
PubMed1996

Ultrasound velocity changes at the proximal phalanxes of the hand in pre-, peri- and postmenopausal women.

We evaluated the bone tissue modifications which occur in pre-, peri- and postmenopausal women by means of an ultrasound (US) device which measures US propagation velocity in the distal metaphysis of the proximal phalanxes of the hand. Before starting the study, two operators assessed the in vivo short-term precision of the device in 12 volunteers, each measured 10 times (5 times by each operator). Then the US velocity in the dominant (DO) and non-dominant (ND) hand was measured in 228 women to evaluate whether there was a difference between US values measured at these sites. Finally, another selected group of 417 healthy pre-, peri- and postmenopausal women, aged from 40 to 65 years, was studied to evaluate the physiological climacteric changes in the US parameter measured: amplitude-dependent speed of sound (AD-SoS). In the 12 volunteers, intra- and inter-observer short-term precision (CV) was 0.4% (for both the operators) and 1.0%, respectively. DO and ND hand AD-SoS values (2074.1 +/- 63.8 m/s and 2077.1 +/- 65.5 m/s, respectively) proved to be highly correlated (r = 0.96, p < 0.0001) in the 228 women studied. AD-SoS distribution (417 subjects) was correlated with age, climacteric condition (premenopause with regular or irregular cycles and natural postmenopause) and body mass index (BMI). In premenopause (253 subjects) the US velocity was higher among women with regular cycles (2107.2 +/- 48.5 m/s) than among those with irregular cycles (2074.7 +/- 44.1 m/s) (p < 0.0001). In postmenopause (164 subjects) an inverse correlation between AD-SoS and the time elapsed since menopause was found (r = -0.42, p < 0.0001). Furthermore, age and BMI were shown to be inversely related to AD-SoS (r = -0.47, p < 0.0001 and r = -0.30, p < 0.0001, respectively) when evaluated in the whole study group. The results obtained confirm that US transmission at the phalanxes is sensitive to pre-, peri- and postmenopausal bone changes. Further studies are needed to evaluate its ability to predict osteoporotic fracture risk.

Adult↗
PubMed1990

The relationship between fecal fat and water in very-low-birth-weight infants.

Metabolic balances were carried out in nine preterm very-low-birth-weight (VLBW) infants, five of whom were fed on expressed breast milk and four on a preterm formula. In 39 stool samples from these infants, there was a very close relationship between the fecal fat and the fecal water (r = -0.95; p less than 0.001), independent of the type of feed. This relationship was present over a very wide range of fat and water contents. Validation experiments confirmed the reproducibility and reliability of this relationship. The correlation is clinically and experimentally so close that measurement of stool water by freeze-drying a sample is an accurate indirect measure of fecal fat in VLBW infants when the daily stool weight was known.

Enteral Nutrition↗
PubMed1987

Effects of dibromochloropropane and ethylene dibromide on biochemical events and ultramorphology of ejaculated ram spermatozoa in vitro.

The effects of dibromochloropropane (DBCP) and ethylene dibromide (EDB) on the function and ultrastructure of freshly ejaculated washed ram spermatozoa were assessed. These two compounds inhibited the collective motility of the sperm in a dose-dependent fashion when the sperm cells generated their energy either by mitochondrial respiration (2-deoxyglucose-treated sperm cells) or by the intact energy production system. DBCP and EDB inhibited the oxygen uptake by the sperm in a dose-dependent manner. No change in lactic acid accumulation and glucose utilization by the sperm cells was noted following DBCP and EDB addition. No change in the collective motility of the sperm was noted when DBCP or EDB were added to spermatozoa treated with the electron transfer inhibitor, antimycin A. Electron microscopy studies of sperm cells treated with DBCP revealed lesions in the plasma membrane adjacent to the acrosome and in the acrosomal membrane forming vesiculations. The inner membrane and the matrix space of the mitochondria were condensed following DBCP treatment, leaving a large mitochondrial peripheral space, compared with the control. EDB, at the concentration studied, caused no change in the ultramorphological structure of the sperm. DBCP was more potent, at least 4-fold, compared with EDB. An in vitro direct effect of DBCP and EDB on ram spermatozoa was established. It is suggested that quantitative measurements of sperm collective motility derived by different metabolic pathways can be used as an in vitro toxicological model for evaluation of toxicological and environmental factors affecting biological systems.

Animals↗
PubMed1987

Plasma amino acids in small preterm infants fed on human milk or formula.

Plasma amino acids were measured in 35 preterm infants, of whom 11 weighed less than 1000 g and 24 weighed between 1000 g and 1500 g at the time of sampling. Repeat samples were obtained in 18 at least seven days later. Seventeen infants were fed with preterm formula milk and 18 with expressed maternal breast milk at one to two hourly intervals during the study period. Formula fed infants gained weight faster than those fed on breast milk but there was little difference in amino acid patterns. Infants fed on breast milk were more likely to have concentrations of essential amino acids below the mid trimester fetal range than formula fed infants, but few infants in either feeding group had values above the fetal range. Those that did were equally distributed between both groups. Only two samples approached toxic concentrations, both in the group fed breast milk. The ratio of branched chain to aromatic amino acids was higher in the group fed on formula after correction for post conceptional age, implying that liver maturation may be accelerated by formula feeding. No correlations were found between plasma amino acid concentrations and nitrogen retention or metabolisable energy intake.

Amino Acids↗
PubMed1980

Hepatobiliary scanning in the diagnosis of acute cholecystitis.

Two hundred seventy-one consecutive hepatobiliary scans (HBS) using technetium Tc 99m iprofenin (Pipida [Sn]) were obtained to evaluate abdominal pain. The material (5 to 10 mCi) was injected and standard anterior and lateral scintographic images were obtained during a one-hour period. An abnormal scan was defined as one in which the gallbladder failed to be seen by one hour with adequate visualization of the biliary tree and proximal gastrointestinal tract. The accuracy of this method was evaluated on the basis of surgical pathology obtained in 117 patients. Of the 76 patients undergoing surgery with an abnormal HBS, 75 had acute cholecystitis, yielding a test accuracy of 98.7%. A normal scan reliably excluded the possibility of acute cholecystitis (100%). Hepatobiliary scanning is presently the most accurate and rapid modality in the diagnosis of acute cholecystitis.

Acute Disease↗
PubMedDate not supplied

Monitoring bone effect of transdermal hormone replacement therapy by ultrasound investigation at the phalanx: a four-year follow-up study.

OBJECTIVE: A controlled 4-year follow-up study was conducted on a population composed of 112 healthy early postmenopausal women to evaluate the ability of ultrasound technology in detecting the effects of hormone replacement therapy (HRT) on bone. At the end of the study, 47 untreated and 25 treated women had been evaluated. Cyclic sequential estrogen/progestogen therapy, 50 microg/day of transdermal 17beta-estradiol (Rotta Research Laboratorium) plus 5 mg/day of medrogestone (Wyeth-Ayerst) was used. DESIGN: Ultrasound transmission through the distal metaphysis of hand phalanxes was measured by DBM Sonic. Beside amplitude-dependent speed of sound (AD-SoS), three new parameters could be calculated: pure speed of sound (pSOS), bone transmission time (BTT), and ultrasound bone profile index (UBPI). Ultrasound measurements were taken at baseline and after 1, 2, and 4 years. RESULTS: Among untreated women a significant decrease of all ultrasound parameters was observed at follow-up measurements. In the HRT-treated group we observed a significant increase of AD-SoS, pSoS, and BTT. We qualified as "responders" women in the treated group for whom AD-SoS, pSoS, and BTT increased by more than 2.77 times the coefficient of variation of the measurement, i.e., 95% variability. Women in the treated group were identified as responders at 4 years of follow-up by AD-SoS (56%), pSOS (56%), and BTT (60%). Ultrasound bone profile index declined in both groups, although to a lower extent among HRT-treated subjects. CONCLUSIONS: The 4-year data confirm the results obtained at 1 and 2 years of follow-up. This study demonstrates that bone tissue investigation by ultrasound at the phalanx can be used to monitor the effect of HRT, and thus it should be considered a potential technology for the management of menopause by gynecologists.

Administration, Cutaneous↗