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J Cannata

Publications and source records attributed to J Cannata.

At least 19 recordsLinked to original sources
PubMed2006

Design and modeling of inversion layer ultrasonic transducers using LiNbO3 single crystal.

Using inversion domain engineering controlled by heating temperature, the LiNbO(3) (LNO) piezoelectric plate with both odd and even-order thickness-extensional modes can be excited simultaneously. Therefore, the inversion layer ultrasound transducer is expected to be capable of operating over a wider frequency range. In this paper, the electrical impedance and the acoustic characteristics of LiNbO(3) (LNO) inversion layer transducer have been studied by finite element modeling (FEM). The transducer designed for this study uses a 36 degrees rotated Y-cut LiNbO(3) thin plate with an active element thickness of approximately 100 microm. First the electrical and elastic properties of the 36 degrees rotated Y-cut LNO were obtained by transforming a basic piezoelectric matrix for Z-cut LNO. In order to validate the FEM using the transformed properties several pieces of pure and 50% inversion layer LNO were tested on the electrical impedance analyzer. The modeled impedance characteristics were consistent with the measured data. Next the model was used to design 50-60 MHz transducers using pure and 30% inversion LNO. Two lambda/4 matching layers and a Tungsten loaded epoxy backing were used in these designs. The modeled results show that an over 90% bandwidth transducer can be made with proper matching and 30% inversion layer.

Computer Simulation↗
PubMed2005

Editorial.

Explore the source record for details and available documents.

Aged↗
PubMed2003

Cardiac troponin I in cats with hypertrophic cardiomyopathy.

The molecular structure of cardiac troponin I (cTnI) is highly conserved across mammalian species and assays developed for its measurement in human patients have been validated in a number of veterinary species. A raised concentration of circulating cTnI is a sensitive and specific marker of cardiac myocyte injury. Raised levels have been documented in a variety of cardiac diseases in both human and veterinary patients. This study compared serum cTnI concentrations between 16 cats diagnosed with hypertrophic cardiomyopathy (HCM) using echocardiography and 18 control cats. The results show that cats with HCM have significantly higher concentration of serum cTnI (median 0.95 ng/ml, range 0.2-4.1 ng/ml) than control cats (median <0.2 ng/ml, range <0.2-0.25 ng/ml) [P<0.0001]. Furthermore in cats with cardiomyopathy a weak correlation was found between the thickness of the left ventricular freewall in diastole measured by ultrasound and serum cTnI concentration (r(2)=0.28;P=0.036). These results suggest that measurement of serum cTnI concentration may enable cats with cardiomyopathy to be distinguished from normal cats using the assay described here.

Animals↗
PubMed2001

The effects of lifestyle, dietary dairy intake and diabetes on bone density and vertebral deformity prevalence: the EVOS study.

The risk of low and moderate energy fracture is related to bone mineral density (BMD). Yet it is uncertain whether the epidemiologic determinants of fracture risk are the same as for low bone density. The European Vertebral Osteoporosis Study was a population-based prevalence study of vertebral deformity in 36 age-stratified population samples aged 50-80 years. In nearly 4000 subjects (13 centers), BMD measurements were also made at the spine, femoral neck and femoral trochanter. To investigate whether effects of reported physical activity on spine deformity risk were mediated through BMD, we modeled these and other risk factor data with BMD as the dependent variate after adjusting for age, center, sex and body mass index (BMI). The significant determinants of vertebral deformity risk were also entered into logistic models of deformity risk that included BMD measurements as covariates. Both current and lifetime physical activity were positively associated with BMD. This effect was stronger with hip BMD than with spine BMD. Lifetime smoking exposure was associated with reduced BMD. Type 2 diabetes mellitus was associated with increased BMD. Weak positive associations were found between consumption of dairy products and BMD at the three measured sites and these were strengthened by an interaction with measures of physical activity in men. Physical activity in women had the largest beneficial effect in lean women and in women exposed to hormone replacement therapy. When fracture risk was modeled with BMD as a covariate, the lifestyle and dietary determinants became less strongly related to vertebral deformity risk, suggesting that BMD may have acted as an intermediary variable. However, heavy physical activity in men still increased spine deformity risk after adjusting for BMD. It is concluded that physical activity in both genders and milk consumption in young women might protect against vertebral deformities in later life through their effects on bone density. The adverse effect of smoking on BMD was confirmed. Heavy physical activity in men might increase spine deformity risk even when BMD is normal.

Absorptiometry, Photon↗
PubMed2000

Different patterns of renal osteodystrophy in Iberoamerica.

The various forms of renal osteodystrophy are predominant hyperparathyroid bone disease, mixed uremic osteodystrophy, low turnover osteomalacia, and adynamic bone disease. The present study analyses a total number of 1,209 bone biopsies from 5 different countries (Brazil, Uruguay, Argentina, Portugal, and Spain). Low turnover osteomalacia and mixed uremic osteodystrophy were more common in Brazil, Uruguay, and Argentina than in Portugal and Spain whereas predominant hyperparathyroid bone disease was seen more often in Portugal and Spain. In all centers, independent of the aluminum staining technique used, the extent of aluminum deposited in bone was greater in patients presenting with low bone turnover, whether from low turnover osteomalacia or adynamic bone disease, than in the predominant hyperparathyroid bone disease. In summary, even though recent reports have indicated that, over the last decade, the incidence of aluminum-induced toxicity was reduced, aluminum still seems to be implicated in a great percentage of symptomatic low bone remodelling lesions in Iberoamerica.

Aluminum↗
PubMed1998

Effects of menstrual history and use of medications on bone mineral density: the EVOS Study.

We have previously shown considerable between-center variation in bone mineral density (BMD) in the 13 EVOS centers that performed bone densitometry on their sex- and age-stratified population samples, after adjusting for weight and age. We have now investigated whether part of the between-center variability may be attributed to between-center variations in the use of medications. Information was collected from 2088 women and 1908 men at baseline on whether the subjects had ever been prescribed calcium, calcitonin, anabolic steroids, fluoride, vitamin D, or glucocorticoids and, for the women, whether they had ever used the oral contraceptive pill (OCP) or hormone replacement therapy (HRT). Each of these variables was fitted into a regression model adjusted for age, height, weight, and center. Only OCP and HRT significantly affected BMD. Those who had ever used OCPs had spinal BMD 0.029 g/cm2 greater than those who had never used them. Users of HRT had higher BMD than nonusers: 0. 037 g/cm2 at the spine, 0.018 g/cm2 at the trochanter, and 0.018 g/cm2 at the femoral neck. As expected, there was a great variation between centers in the use of OCP and HRT, but there were no significant correlations between mean BMD at any site in a given center and the prevalence of OCP or HRT use in that center. The between-center variance in BMD at all three sites remained highly significant after adjusting for treatment (P < 0.001). We conclude that HRT and OCP use are associated with moderate increases in BMD. The geographical variability of BMD in Europe was not explained by treatment with pharmaceuticals.

Absorptiometry, Photon↗
PubMed1998

Ultrafiltrable aluminium after very low doses of desferrioxamine.

BACKGROUND: The recommended dose of desferrioxamine for the treatment of aluminium intoxication is 5 mg/kg/week. However, there are no data about the efficiency of lower doses. The objective of this study was to investigate the capacity of very low doses of desferrioxamine in the generation of ultrafiltrable aluminium. METHODS: Five patients undergoing haemodialysis with a similar biochemical profile and serum aluminium levels >40 microg/l were studied. The three different doses of desferrioxamine used (0.5, 2.5 and 5.0 mg/kg) were administered randomly to each patient at 1 week intervals. Total and ultrafiltrable serum aluminium was measured before and 44 h after the administration of desferrioxamine. RESULTS: All doses of desferrioxamine significantly increased the total serum aluminium; no differences were found between 2.5 and 5.0 mg/kg. The total serum aluminium levels doubled with the 2.5 and 5.0 mg/kg doses, while the increase with 0.5 mg/kg was lower (32.6%, P<0.05). Ultrafiltrable aluminium increased with the three doses; from 7.1+/-2.8, 3.9+/-0.6 and 7.5+/-4.1 to 25.7+/-7.3, 44.3+/-10.1 and 59.1+/-19.8 microg/l, respectively (P<0.05). The efficiency of each dose was calculated using the ratio between the increase in ultrafiltrable aluminium and the dose of desferrioxamine administered. The efficiency ranged from 10.3+/-3.9 for the higher dose (5 mg/kg) to 37.2+/-10.3 for the lower dose (0.5 mg/kg). CONCLUSIONS: Our results suggest that very low-dose desferrioxamine (>5 mg/kg) increases the ultrafiltrable (potentially dialysable) aluminium.

Aged↗
PubMed1997

Population-based geographic variations in DXA bone density in Europe: the EVOS Study. European Vertebral Osteoporosis.

The purpose of this study was to investigate variations in bone density between 16 European populations, 13 of which were participants in the European Vertebral Osteoporosis Study (EVOS). Men and women aged 50-80 years were recruited randomly from local population registers, stratified in 5-year age bands. The other three centres recruited similarly. Random samples of 20-100% of EVOS subjects were invited for dual-energy X-ray absorptiometry (DXA) densitometry of the lumbar spine and/or proximal femur using Hologic, Lunar or Norland pencil beam machines or, in one centre, a Sopha fan-beam machine. Cross-calibration of the different machines was undertaken using the European Spine Phantom prototype (ESPp). Highly significant differences in mean bone density were demonstrated between centres, giving rise to between centre SDs in bone density that were about a quarter of a population SD. These differences persisted when centres using Hologic machines and centres using Lunar machines were considered separately. The centres were ranked differently according to whether male or female subjects were being considered and according to site of measurement (L2-4, femoral neck or femoral trochanter). As expected, bone mineral density (BMD) had a curvilinear relationship with age, and apparent rates of decrease slowed as age advanced past 50 years in both sexes. In the spine, not only did male BMD usually appear to increase with age, but there was a highly significant difference between centres in the age effect in both sexes, suggesting a variability in the impact of osteoarthritis between centres. Weight was consistently positively associated with BMD, but the effects of height and armspan were less consistent. Logarithmic transformation was needed to normalize the regressions of BMD on the independent variates, and after transformation, all sites except the femoral neck in females showed significant increases in SD with age. Interestingly, the effect of increasing weight was to decrease dispersion in proximal femur measurements in both sexes, further accentuating the tendency in women for low body mass index to be associated with osteoporosis as defined by densitometry. It is concluded that there are major differences between BMD values in European population samples which, with variations in anthropometric variables, have the potential to contribute substantially to variations in rates of osteoporotic fracture risk in Europe.

Absorptiometry, Photon↗
PubMed1997

Bone density variation and its effects on risk of vertebral deformity in men and women studied in thirteen European centers: the EVOS Study.

In Europe there is a 3-fold variation, according to geographical center, in risk of vertebral deformity in men and women over the age of 50. We investigated the relationship between bone density, as assessed by dual-energy X-ray absorptiometry (DEXA) of the spine and hip and prevalent vertebral deformities in 13 of the 36 centers participating in the European Vertebral Osteoporosis Study (EVOS). Each center recruited an age-stratified sample of men and women aged 50 years and over, and of those who agreed to densitometry, 288/2088 women and 233/1908 men were found to have one or more deformities of the vertebrae between T4 and L4 as assessed by the McCloskey algorithm. DEXA was in each case performed on L2-L4, the proximal femur, or both. Bone densitometry results were cross-calibrated between centers using the European Spine Phantom prototype and results expressed as bone mineral density (BMD, g/cm2). In both genders, subjects with deformities involving loss of anterior vertebral body height alone comprised over 20% of the total with deformities and these related poorly to BMD. Other classes of deformity were found by logistic regression to relate significantly to BMD in one or both genders, with odds ratios for the risk of any of these ranging from 1.67 to 2.11 for a 1 SD reduction in bone density at spine, femoral neck, or trochanter (p < 0.001). Adjusting for anthropometric variables and BMD did not remove the effect of age on risk which rose 1.67- to 1.78-fold per decade according to gender. The greater unadjusted rate of increase in deformity risk with age in women was attributable to their faster rate of bone loss with age; after adjusting for age, body mass index (BMI), and BMD at the trochanter in grams per square centimeter, men had a 2-fold higher risk of deformity than women. Analysis of the relationship between mean bone density and the prevalence of deformity in each center demonstrated no significant differences between centers in either gender, after adjusting for BMD, age, and BMI together with an a posteriori statistical adjustment for imperfect cross-calibration of densitometers. It is concluded that BMD is an important determinant of deformity risk in both genders. Together with age, BMD explains much of the differences in risk both between the sexes and between individual geographical centers in Europe.

Aged↗
PubMed1996

Systemic aluminum toxicity: effects on bone, hematopoietic tissue, and kidney.

Although the full mechanisms are not yet elucidated, research into the mechanism of toxicity of aluminum (Al) on bone formation and remodeling and on hematopoietic tissue is ongoing. In contrast little information exists on the interactive effects of systemic Al and the kidney. In bone, both clinically and experimentally, high doses of Al inhibit remodeling, slowing both osteoblast and osteoclast activities and producing osteomalacia and adynamic bone disease. In contrast, while very low levels of Al are mitogenic in bones of experimental animals, the effect of low levels of Al in humans is unknown. Aluminum has been shown to have its mitogenic action at the osteoblast, but whether the effect on resorption is viz osteoblast-directed changes in osteoclast activity has not yet been determined. Parathyroid hormone (PTH) levels are disrupted by Al in humans and animals. Whether altered PTH levels play a major or even a minor role in Al-dependent osteotoxicity requires clarification. In hematopoietic tissue, Al causes a microcytic anemia, not reversible by iron. Friend leukemia cells treated with Al have been reported to accumulate excess iron, without incorporating it into ferritin or heme. It is not yet known which steps in iron metabolism are disrupted by Al, if they involve a single mechanism of action, or even if this disruption in iron metabolism accounts for the anemia seen in Al toxicosis. In kidney, research is needed to evaluate Al nephrotoxicity; there are almost no studies in this area. Furthermore, research is needed to evaluate mechanisms of renal Al excretion, presently shown by one study to occur at the distal tubule. Such studies might well throw light on whether Al plays a role in aggravating renal insufficiency, or whether the role of the kidney in Al toxicosis is limited to the causative effect of renal compromise on Al accumulation. In summary, while a number of mechanisms have been proposed for the toxic action of Al, no single mechanism emerges to explain these diverse effects of systemic Al. Recommendations for future research are presented and summarized in Table 1.

Aluminum↗
PubMed1996

Influence of aluminium overload on the course of post-transplant parathyroid function.

Aluminium intoxication exerts profound effects on secondary hyperparathyroidism in chronic renal failure and could influence the evolution of post-transplant parathyroid function. We have evaluated 44 patients after successful renal transplantation, sequentially from day 0 up to day 90 from the beginning of graft function, determining serum and urinary aluminium, PTH (intact molecule) and several other parameters of mineral metabolism. Patients were grouped according to their basal serum aluminium: Group LA (n = 25) had serum aluminium less than 40 micrograms/l (mean 21 +/- 10 micrograms/l), and Group HA (n = 19) had serum aluminium greater than 40 micrograms/l (mean 100 +/- 43 micrograms/l). This latter group also had greater urinary aluminium excretion during the study period. Evolution of renal function was similar in both groups. Group LA had increased pre-transplant iPTH (353 +/- 416 pg/ml vs 175 +/- 94, P = 0.05). Seven days after regaining renal function both groups showed a marked decrease in iPTH and then a continued decline up to day 90 with mean serum values of the hormone showing no further differences between groups. The incidence of hypercalcaemia was similar in both groups but no patients in Group HA developed hypercalcaemia at post-transplant day 7 while 12% in Group LA did so. Urinary phosphate excretion and the incidence of post-transplant hypophosphataemia were similar in both groups. These findings suggest: (a) patients with more aluminium intoxication have lower values of pre-transplant iPTH and they correct parathyroid function in a different way than non-intoxicated patients in early post-transplant days; (b) they have lower and later incidence of hypercalcaemia.

Adolescent↗
PubMed1995

A comparison of albumin, polygeline and crystalloid priming solutions for cardiopulmonary bypass in patients having coronary artery bypass graft surgery.

This study was designed to assess the effect of different prime solution compositions on a patient's fluid balance, transfusion requirements, renal function and haemodynamic stability over the first 24 hours postbypass. Ninety-three patients presenting for first-time coronary artery bypass graft (CABG) surgery were randomly allocated to receive one of three prime solutions for the CPB pump: albumin (4.6%) + Plasmalyte (Group A, n = 32), polygeline (Hemaccel) + Plasmalyte (Group P, n = 29), or crystalloid (Plasmalyte) alone (Group C, n = 32). Patients, anaesthetists, surgeons and intensive care unit (ICU) staff were all blinded as to the solution type. The groups were demographically and haemodynamically similar. There were no differences between the groups with respect to white cell or platelet counts during the study. There was a significant difference in haemoglobin levels between the groups on weaning from CPB and on arrival in the ICU (Group C > Groups P and A, p < 0.001 for both times). There was no difference in blood transfusion requirements between any of the groups. During CPB, Group C required significantly more crystalloid than the other groups (p < 0.001). Urine output was significantly higher in Group C compared with Groups P and A at all time periods up to and including ICU 12 hours (p < 0.05). The use of frusemide was significantly higher in the ICU in Groups P and A (p < 0.01). There was a net gain of 3132 +/- 412 ml in Group C in 24 hour fluid balance, which was significantly higher than Group A (2166 +/- 223 ml, p = 0.04). Our results show that, in this patient population, there is no advantage in using a colloid-based prime solution over a purely crystalloid solution from a haemotologic or haemodynamic point of view for the first 24 hours after CPB. There appears to be an increase in extracellular fluid (ECF) retention in Group C, but this caused no related problems in the study period. On the other hand, diuretics (frusemide) needed to be given significantly less often in these patients to offset oliguria.

Albumins↗
PubMed1990

Regional cerebral blood flow after hemorrhagic hypotension in the preterm, near-term, and newborn lamb.

Developmental changes in regional cerebral blood flow (CBF) responses to hemorrhagic hypotension during normoxia and normocapnia were determined using radioactively labeled microspheres to measure flow to the cortex, brainstem, cerebellum, white matter, caudate nucleus, and choroid plexus in three groups of chronically catheterized lambs: 90- to 100-d preterm fetal lambs (n = 9); 125- to 136-d near-term fetal lambs (n = 9); and newborn lambs 5- to 35-d-old (n = 8). Heart rate, central venous pressure, and arterial blood pressure were monitored continuously and arterial blood gas tensions, pH, Hb, and oxygen saturation together with regional CBF were measured periodically. Hemorrhagic hypotension produced a mean decrease in arterial blood pressure of 27 +/- 4, 23 +/- 2, and 41 +/- 4% in the three groups, respectively, whereas reinfusion of the lamb's blood resulted in a return to control blood pressure within 3% in all three groups. In the pre-term fetal lamb, CBF decreased significantly in all regions during hypotension. In the near-term fetal lamb, only blood flow to the cortex decreased significantly during hypotension. In the newborn lamb, only the choroid plexus demonstrated a significant decrease in blood flow during hypotension. The lower limit of regional CBF autoregulation was identical to the resting mean arterial pressure in fetal life but significantly lower in newborn lambs. These experiments demonstrate for the first time that vulnerability to hypotension decreases with increasing maturity and that the brainstem, the phylogenetically oldest region of the brain, is the least vulnerable to the effects of hypotension at any age in the lamb model.

Animals↗
PubMed1989

EEG monitoring using aperiodic analysis during carotid and open heart surgery.

The Cerebral Electrical Activity (CEA) was monitored by Lifescan in 38 patients undergoing carotid surgery under general or regional anaesthesia and another 20 patients during cardiopulmonary bypass undergoing open heart surgery. This monitor uses aperiodic analysis to process the electroencephalogram. Abrupt changes in CEA were observed when blood flow was disrupted due to surgical intervention or administration of thiopentone. Gradual changes in CEA were due to anaesthesia or hypothermia. In one patient a long period of depressed CEA did not result in a neurological deficit and in another patient a neurological event was undetected by the monitor.

Cardiac Surgical Procedures↗
PubMed1988

Developmental changes in regional cerebral blood flow in fetal and newborn lambs.

Developmental changes in regional cerebral blood flow (CBF) were determined using radioactively labeled microspheres to measure flow to the cortex, brain stem, cerebellum, white matter, caudate nucleus, and choroid plexus in three groups of chronically catheterized lambs under physiological conditions: 90- to 100-day preterm fetal lambs (n = 14), 125- to 136-day near-term fetal lambs (n = 11), and newborn lambs 5-44 days old (n = 10). We continually monitored heart rate, central venous pressure, and mean arterial blood pressure (MAP) and periodically measured arterial blood O2 and CO2 tensions (PaO2, PaCO2, respectively), pH, hemoglobin, and oxygen saturation (SaO2). The regional CBF measurements (ml.100 g-1.min-1) revealed that in all three age groups the high flow areas are the choroid plexus and caudate nucleus, whereas the lowest flow area is the white matter. There is, however, a different hierarchy of regional CBF in utero (cortex less than cerebellum and brain stem) compared with extrauterine life in the newborn lamb (cortex and cerebellum greater than brain stem). Analysis of regional cerebral oxygen delivery [CBF times arterial oxygen content (CaO2)] demonstrated a progressively increasing oxygen transport to the cortex with increasing gestational maturity and after birth. Oxygen transport to the brain stem, cerebellum, and white matter increased with gestational age, but did not increase after birth. Relationships between regional CBF and natural physiological variations of cardiorespiratory parameters (PaO2, SaO2, CaO2, pH, PaCO2, and MAP) were assessed using regression analysis. Correlations of regional CBF with PaO2 and SaO2 suggest that cerebral perfusion is not primarily determined by CaO2 when variations occur within the physiological range.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Ultrastructure of the myocardium during development from early fetal life to adult life in sheep.

The ultrastructure of the developing fetal lamb myocardium was studied in a series of animals spanning 29 days of gestation to term, and compared with newborn and adult animals. All major ultrastructural features which characterise the adult myocyte were found in early fetal life, although with considerably different degrees of development of specific features. Notably, myofibrils at 29 days of gestation are sparse and show little organisation. With advancing gestation there is an increasing number of myofibrils and the development of well defined striations. Thus, at term, the fetal tissue is not substantially different from the adult myofibril in the appearance of sarcomere structure. The observation of contractile tissue paucity and disorder in early fetal lamb myocardium is difficult to reconcile with available physiological data, which show an extraordinary pumping performance of the heart in vivo, and requires further investigation.

Animals↗