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Biomedical subjects

M Tacconi

Publications and source records attributed to M Tacconi.

At least 19 recordsLinked to original sources
PubMed1999

Enzyme kinetic parameters are not altered by microgravity.

This paper deals with a microgravity experiment concerning the EMEC project (Effect of Microgravity on Enzymatic Catalysis), performed during the parabolic flight of the sounding rocket MASER 7, launched from the base of Esrange (Kiruna, Sweden) on May 3, 1996. The experiment consisted of performing, in a microgravity environment, a number of velocity measurements of an enzyme (isocitrate lyase) catalyzed reaction at different substrate concentrations, to calculate the kinetic parameters (Km and Vmax), which were compared with those obtained at standard gravity, with identical instrumentation. The experimental hardware, the EMEC module, expressly set up by Officine Galileo (Firenze, Italy) with the financial support of the European Space Agency, was a multichannel fibre-optics radiometer, equipped with an automatic injection system, that allowed to measure simultaneously the transmittance changes in 16 reaction cells. The results indicated that under the experimental conditions applied, microgravity has no appreciable effect on the enzyme kinetic constants.

Catalysis↗
PubMed1998

ESS, eye stimulator system for VVIS facility (Visual and Vestibular Investigation System).

The ESS (Eye Stimulation System) is one of four main Subsystems of the Visual and Vestibular Investigation System ( VVIS ), Facility developed in the field of EDEN program and aimed to the research in the area of neurosensors physiology under microgravity conditions. In particular, the ESS is an Optokinetic Stimulator that stimulates the Subject's eyes with moving black and yellow patterns, in order to allow, by another main Subsystem, video recording of the pupil movement and, successively, to elaborate the relevant data of the neurovestibular experiment. This Stimulator was designed by the Officine Galileo as Subcontractor of Aerospatiale, leader of the VVIS facility, developed under ESA contract and successfully flown in April 1998 aboard the Neurolab mission. The Eye Stimulation System, on the frame of the VVIS Facility, is used in conjunction with the Body Rotating Device and the Eye Movement and Recording System, in order to fulfill all operations that lead to carry-out the experiments proposed. The Subject, seated on the Rotating Chair, observes the stimuli on a display monitor through a set of lenses, mounted on a proper box, fixed to a main structure of the unit. The stimuli patterns are showed on a display, placed on a movable support in order to fix it in a proper position, depending on the optical characteristics of the Subject. The experiments are repeated with different kind of patterns. All the main components of the visual system are mounted on a structural base plate, that gives also the mechanical I/F with the other system, supporting the ESS.

Computer Graphics↗
PubMed1998

Use of a donor aortic cross for arterial reconstruction of the pancreaticoduodenal allograft.

Combined liver-pancreas procurement generally requires back bench reconstruction of the arterial blood supply with a donor Y-iliac graft to the pancreas graft. A modified vascular reconstruction that uses donor aortic cross including the brachiocephalic trunk and the left carotid artery as a single arterial patch is presented. This is useful when iliac grafts are unavailable or are being used as an alternative technique.

Anastomosis, Surgical↗
PubMed1997

Octreotide long-term treatment in patients with portal hypertension: persistent inhibition of postprandial glucagon response without major changes in renal function.

BACKGROUND/AIMS: Octreotide acutely decreases splanchnic blood flow and postprandial portal pressure in patients with portal hypertension. Inhibition of glucagon release parallels the hemodynamic changes. We studied the hormonal and renal effects of long-term treatment with octreotide (100 microg s.c., t.i.d., immediately before meals, for 2 weeks) in 12 patients with cirrhosis and portal hypertension. METHODS: Postprandial blood levels of glucagon, insulin and glucose, and renal function tests were monitored in a study where patients acted as their own controls. Eleven patients completed the study, octreotide being discontinued in one patient who developed jaundice after 6 days of therapy. RESULTS: Long-term treatment did not cause any change in fasting hormonal levels measured 12 h after the last injection of octreotide. However, pre-prandial injection of octreotide induced a marked fall in blood glucagon (163+/-49 pg/ml, after 20 min, vs. 254+/-71 pg/ml, basal; p<0.01), thus preventing the postprandial response occurring without treatment (322+/-102 pg/ml, 30 min-peak, vs. 249+/-77 pg/ml, basal; p<0.03). Inhibition of postprandial glucagon was maintained after 2 weeks of therapy (159+/-33 pg/ml, after 20 min, vs. 237+/-54 pg/ml, basal; p<0.01). Octreotide abolished the insulin postprandial response with no major change in glycemic control. Treatment had no long-term effect on renal plasma flow (effective renal plasma flow: 596+/-79 ml/min, baseline, vs. 609+/-71 ml/min, at 2 weeks; p>0.5), glomerular filtration rate (glomerular filtration rate: 99+/-11 vs. 99+/-12 ml/min; p>0.5), blood urea and creatinine, whereas it induced a mild decrease in plasma electrolyte levels (p<0.02). CONCLUSIONS: Long-term octreotide treatment persistently suppresses the postprandial glucagon response of patients with portal hypertension without causing deterioration in their renal function.

Adult↗
PubMed1997

The influence of dietary nucleotides on erythrocyte membrane fatty acids and plasma lipids in preterm infants.

OBJECTIVE: The objective of this study was to evaluate whether a regular formula for premature infants supplemented with nucleotides has any influence on plasma lipids and erythrocyte membrane fatty acids. METHODS: Preterm infants fed either human milk supplemented with human milk protein (HM, n = 14), nucleotide-supplemented preterm formula (NF, n = 13), or a regular preterm formula (F, n = 13) were included in the study. The NF was supplemented with 18.2 mg cytidine monophosphate/l (CMP), 7.0 mg uridine monophosphate/l (UMP), 6.4 mg adenosine monophosphate/l (AMP), 3.0 mg inosine monophosphate/l (IMP) and 3.0 mg guanosine monophosphate/l (GMP). RESULTS: There were significantly higher concentrations of triglycerides (TG) in infants fed NF compared to those fed F (191.42 +/- 79.58 vs 108.21 +/- 43.73, p < 0.001, mean +/- SD lipid concentrations, mg/100 ml plasma). Infants fed F had significantly lower concentrations of total cholesterol (94.34 +/- 11.71 vs 115.69 +/- 39.29, p < 0.01) and TG in plasma (108.21 +/- 43.73 vs 172.27 +/- 68.19, p < 0.001, mean +/- SD lipid concentrations, mg/100 ml plasma) when compared to HM-fed infants. There were no significant differences in any of the erythrocyte membrane fatty acids and total long-chain polyunsaturated fatty acids (LC-PUFA) between NF and F during the study period (6 weeks). Furthermore, total LC-PUFA and docosahexaenoic acid (DHA) concentrations in red blood cell were not significantly different when infants fed NF were compared to those fed HM. In contrast, however, infants fed F had significantly lower concentrations of total n-3 LC-PUFA (p < 0.01) and DHA (p < 0.01) than those found in HM-fed infants. CONCLUSIONS: These results do not suggest an effect of nucleotides on the red blood cell LC-PUFA profile in preterm infants. However, the nucleotides may increase the concentrations of triglycerides in plasma.

Cholesterol↗
PubMed1993

Fat absorption and gastroenteric pH profile in postsurgical pancreatic insufficiency: role of the association of H2-receptor antagonists with pancreatic enzymes.

The complete control of steatorrhea in post-surgical exocrine pancreatic insufficiency is difficult. The aim of this study was to evaluate the effect of the association of ranitidine with pancrelipase om fecal fat excretion in patients who had undergone a pancreatoduodenectomy with suppression of the exocrine pancreatic secretion by Neoprene injection. Ten patients were studied 1 year after surgery. Steatorrhea was measured as an integrated test of 3-day stools, while patients were kept on a diet of 100 g lipid/day, with their usual enzyme supplementation therapy (16,050 USP units of lipase/meal). A basal 24-h gastroenteric pH profile was also obtained. In the following month, patients had ranitidine (150 mg twice a day) in addition to pancrelipase. Then steatorrhea and gastroenteric pH were reassessed. Mean fecal fat was 26.9 (SD 13.7) g/day without ranitidine and 30.5 (SD 13.9) g/day during combined treatment. Body weight and nutritional parameters did not show any significant variation after ranitidine administration. Even in the absence of ranitidine, postprandial gastroenteric pH values were always > 4; the H2-receptor antagonist only reduced fasting gastric acidity. In conclusion, the gastroenteric pH and fecal fat determinations showed that ranitidine is not useful in patients with total postsurgical exocrine pancreatic insufficiency.

Adult↗
PubMed1992

Clinical utility of the serum CA 19-9 test for diagnosing pancreatic carcinoma in symptomatic patients: a prospective study.

The diagnostic accuracy of the serum CA 19-9 determination was prospectively evaluated in patients selected for the presence of signs or symptoms highly suggestive for pancreatic cancer. Of 110 patients included in the study, 54 had a final diagnosis of pancreatic adenocarcinoma (49% prevalence). CA 19-9 values were higher than 40 U/ml in 45 patients with pancreatic carcinoma and in 18 of the 56 patients with other final diagnosis (sensitivity, 0.83; specificity, 0.68; positive predictive value [PPV], 0.71; negative predictive value [NPV], 0.81). The serum CA 19-9 determination was not capable of shortening the diagnostic workup of patients with strong clinical suspicion of pancreatic cancer since adequate imaging of the pancreas was required to confirm or exclude the diagnosis. However, values above 120 U/ml were strongly suggestive for pancreatic carcinoma in the overall population (PPV, 0.85) and they were diagnostic (PPV, 1.0) in the anicteric portion. Combined with pancreatic imaging, the CA 19-9 was an excellent confirmatory test; a normal value in a patient with negative imaging ruled out pancreatic carcinoma as the cause of symptoms (NPV, 1.0), whereas a pathological result in the presence of positive or equivocal pancreatic radiology was highly suggestive for the presence of the disease (PPV, 0.93).

Adenocarcinoma↗
PubMed1992

Dose-response effects of oral loxiglumide on postprandial gall-bladder emptying in man.

The effect of two different single oral doses of loxiglumide (CR 1505, CAS 107097-80-3) on gall-bladder emptying induced by a 550-cal standard mixed meal in 6 healthy volunteers was studied. Following placebo, the maximal gall-bladder emptying occurred about 90 min after the meal (minimal residual gall-bladder volume 27.4% of basal volume). Loxiglumide 400 or 800 mg dose-dependently inhibited the physiologica gall-bladder emptying. Loxiglumide plasma levels dose-dependently increased. The inhibition of gall-bladder emptying and the kinetic of loxiglumide plasma levels were temporally related. The results of the present study confirm that oral loxiglumide is a potent orally active cholecystokinin (CCK) antagonist in man and that CCK is the major physiological mediator of gallbladder emptying in response to meal.

Adult↗
PubMed1991

What will be the adult height of coeliac patients?

We studied three groups of patients with coeliac disease: group 1 = 95 adult patients with gastro-intestinal symptoms diagnosed after reaching adult height, 41 of whom had had symptoms during childhood; group 2 = 23 adult patients with classic coeliac disease treated before or during puberty; group 3 = 11 coeliac children with short stature and no gastro-intestinal symptoms diagnosed and treated before or during puberty. We evaluated the adult height in groups 1 and 2 and the growth during the first years of diet in group 3. Our study leads us to the following conclusions. Dieting leads to a modest increase (on average not more than 3 cm) of the final height of coeliac patients. Subjects with gastro-intestinal symptoms who have been treated before adulthood reach a mean height similar to the normal population and have a slightly better adult height than non-treated subjects. This difference seems to exist only in men and this might be related to puberty evolving more rapidly in women receiving treatment. Subjects without symptoms during childhood reach a normal final height even without treatment. In our patients, early treatment seemed to have no great effect on adult height.

Adolescent↗
PubMed1991

Serum DU-PAN-2 in the differential diagnosis of pancreatic cancer: influence of jaundice and liver dysfunction.

The usefulness of serum DU-PAN-2 in diagnosing pancreatic cancer and in distinguishing between this cancer and other benign and malignant diseases, and to assess the role of liver dysfunction in altering the serum levels of this marker were investigated. DU-PAN-2 was measured in the sera of 31 patients with pancreatic cancer, 32 with chronic pancreatitis, 20 with benign and 21 with malignant extra-pancreatic diseases. DU-PAN-2 was found to be above 300 U ml-1 in 21/31 patients with pancreatic cancer (sensitivity 68%). Only 3/32 patients with chronic pancreatitis had abnormal values. A substantial number of patients with both benign and malignant extra-pancreatic diseases had an elevated serum DU-PAN-2 (9/20 and 15/21, respectively). Correlations were found between DU-PAN-2 and (1) total bilirubin, (2) alanine-amino-transferase and (3) alkaline phosphatase. Of the patients with high DU-PAN-2 values, jaundice was found in: 2/3 with chronic pancreatitis, 9/10 with benign and 12/14 with malignant extra-pancreatic diseases. In conclusion, the serum DU-PAN-2 test for pancreatic malignancy is not completely satisfactory, because it is not sensitive enough. While the test for chronic pancreatitis has an acceptable specificity, the assay cannot distinguish between pancreatic cancer and other extra-pancreatic diseases, mainly of the liver and biliary tract. Liver dysfunction as well as jaundice seem to considerable affect the levels of this marker, as reported elsewhere for CA 19-9.

Adult↗
PubMed1990

Effect of loxiglumide on gallbladder contractile response to cerulein and food in humans.

The present study investigated the effect of loxiglumide, a new selective cholecystokinin-receptor antagonist, on the gallbladder contractile responses to caerulein and to food in humans. In 6 healthy men, the gallbladder emptying driven by intravenous infusion of stepwise increasing doses of cerulein (10-80 ng/kg . h) and that induced by a 550-cal standard meal were monitored by ultrasonography. In both sets of experiments, the effect of loxiglumide was tested at various infusional rates against a control infusion of saline. An infusional rate of 2.5 mg/kg . h of loxiglumide abolished the gallbladder response even to maximal doses of cerulein, whereas a rate of 1.0 mg/kg . h counteracted the cholecystokinetic activity of cerulein up to the dose of 20 ng/kg . h. In postprandial experiments, the cholecystokinin antagonist dose-dependently inhibited the physiologic gallbladder contraction. The maximal gallbladder emptying, which always occurred 85 min after the meal, was 71.1% +/- 3.3% of basal volume in control studies, 39.2% +/- 1.8% during infusion of 2.5 mg/kg . h of loxiglumide, and 17.3% +/- 5.9% when 5.0 mg/kg . h were infused. A dose of 7.5 mg/kg . h of loxiglumide was able to prevent any postprandial emptying of the gallbladder. The present study shows that a selective cholecystokinin receptorial blockade competitively antagonizes cerulein-induced gallbladder contraction and dose-dependently inhibits postprandial gallbladder emptying.

Adult↗
PubMed1990

Microalbuminuria in diabetic children and adolescents. Relationship with puberty and growth hormone.

Urinary albumin excretion (UAE) was determined by radioimmunoassay in two 24 h urine collections from 125 diabetic children and adolescents and from 71 normal children matched for age and sex. Thirteen patients (10.4%) aged greater than 12 years had microalbuminuria, i.e. log transformed UAE levels above the upper normal range (24.5 mg/24 h). UAE values were positively correlated with age, GH secretion, but not with duration of disease, glycosylated hemoglobin, renal size or N-acetyl-beta-glucosaminidase excretion. Diabetic normoalbuminuric children aged 10 years and older had significantly higher UAE than controls and than younger diabetic patients matched for duration of disease. HLA DR3/DR4 heterozygosity frequency was significantly higher (p less than 0.01) in the microalbuminuric group than in the normoalbuminuric. All microalbuminuric subjects (n = 8) with short duration of disease (3.92 +/- 3.43 yr) developed diabetes at puberty. In conclusion, our cross-sectional study suggests: if a number of factors are combined, i.e. HLA DR3/DR4 heterozygosity, onset of disease at puberty and higher GH values, the probability of developing abnormal levels of UAE will increase.

Adolescent↗
PubMed1990

Incidence of intratubular germ cell neoplasia in androgen insensitivity syndrome.

Gonadal histology was investigated by means of conventional microscopy in 6 patients with complete androgen insensitivity syndrome, in 11 with incomplete androgen insensitivity syndrome, and in 3 with 5 alpha-reductase syndrome. Twelve subjects were prepubertal and 8 pubertal. In all patients gonadal tissue was removed as a prophylactic measure and no patients gave rise to any clinical suspicion of a tumour. Eight patients with incomplete androgen insensitivity syndrome, 5 of whom (62.5%) were prepubertal, showed intratubular germ cell neoplasia and in 6 of them it was bilateral. Histochemical and immunohistochemical analysis showed considerable agreement between atypical morphological aspects and positive response to Schiff's periodic acid and to staining with the anti-placenta alkaline phosphatase antibody. Our patients were characterized by one of the highest reported incidences of intratubular germ cell neoplasia, particularly at prepubertal age. These findings would seem to indicate that a rethink is needed concerning the general opinion that patients with androgen intensivity syndrome have practically no risk of developing malignancy, and that orchidectomy is not advisable before puberty is completed.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1989

Effect of gonadectomy on growth hormone, IGF-I and sex steroids in children with complete and incomplete androgen insensitivity.

IGF-I, testosterone and estradiol levels were evaluated in 8 girls with androgen insensitivity immediately before and from 1 to 3 months after bilateral gonadectomy. In 6 patients GH secretion was evaluated before and after gonadectomy by means of an arginine test and in 3 a sleep test was also performed. Mean IGF-I level before surgery was significantly higher than that of normal controls (2850 +/- 1230 vs 1680 +/- 1040 U/l, p less than 0.025). After gonadectomy a significant decrease was evident for testosterone, estradiol and IGF-I levels. A positive correlation between IGF-I and estradiol levels was present before surgery (p less than 0.005). The presence of a correlation with estradiol, but not with testosterone, and the knowledge that this syndrome is due to an insensitivity to androgens, but not to estradiol, support the hypothesis that the estradiol level is the major determinant for the control of IGF-I values in these patients. After gonadectomy, a substantial decrease of the 12-h nocturnal GH secretion was evident. Comparison of the nocturnal GH levels before surgery of the 3 patients with those of normal subjects of the same age showed hormonal values higher than 1 SD over the mean values of control subjects. Even if the number of patients studied is too small to draw any definitive conclusion, these data may suggest that sex hormones play a role in the control of IGF-I levels, a function which seems to be mediated through GH secretion.

Adolescent↗
PubMed1988

Haemorheologic and fibrinolytic evaluation in obese children and adolescents.

The haemorheologic condition was evaluated in 43 obese children and 35 controls. In 18 of the obese children and in 21 controls the euglobulin lysis time (ELT) was also studied. Blood viscosity at 94.5 and at 0.204 s-1 shear rates, plasma viscosity, fibrinogen and erythrocyte filtration time were significantly higher in obese than in control children. No significant differences were observed in haematocrit levels. Triglycerides, non-esterified fatty acids (NEFA), pre-beta-lipoprotein and insulin rates were all significantly higher in obese than in control children. There were no significant differences in glycaemia and in haemoglobin A1 values. ELT, both basal and after stimulation with 1-deamino-8-D-arginine-vasopressin (DDAVP), was significantly higher in the obese than in control children. The haemorheologic disturbances together with alterations of the haemostatic balance and fibrinolysis may be an important risk factor for the development of vascular changes at paediatric age.

Adolescent↗
PubMed1986

Adrenocortical tumours in children: our experience with nine cases.

Nine cases of adrenocortical tumor are presented, six were males. Four were less than three years and five were between 5 and 10 years of age. Clinical virilization was found in 8 children, one had only signs of hypercortisolism and another showed signs of virilization and hypercortisolism simultaneously. Urinary 17-KS and 17-OHCS were high in all patients. Plasma levels of testosterone and of the other adrenal androgens were high in all the cases tested. Plasma level of cortisol was elevated only in few cases. In two out of five cases steroids were only partially suppressed by dexamethasone. Computed tomography and abdominal sonography have been useful tools for the localization of the tumour. The resection of the tumour, independent of histopathological diagnosis, led to a complete normalization of the clinical and hormonal picture in eight cases evaluated at a distance of 2 months 10 years after surgery. In one case a hepatic metastasis was observed and removed three years after surgery.

17-Hydroxycorticosteroids↗
PubMed1985

Phosphatidylcholine produced in rat synaptosomes by N-methylation is enriched in polyunsaturated fatty acids.

Rat brain synaptosomes contain an enzyme, phosphatidylethanolamine N-methyltransferase (EC 2.1.1.17), that catalyzes the methylation of phosphatidylethanolamine to form its mono-, di-, and trimethyl (phosphatidylcholine) derivatives. Synaptosomal phosphatidylethanolamine is much richer in polyunsaturated fatty acids (43.4%) than is synaptosomal phosphatidylcholine (4.6%). It thus seemed possible that the phosphatidylcholine derived via the N-methylation of phosphatidylethanolamine might also be especially enriched in polyunsaturated fatty acids. To test this hypothesis, we examined the incorporation of [3H]methyl groups into various molecular species of phosphatidylcholine, by incubating rat synaptosomes for 10, 30, or 90 min in a medium containing S-adenosyl[methyl-3H]methionine. Phosphatidylcholine was extracted and separated from other lipids by TLC, after which its molecular species were isolated by argentation TLC (which distinguishes among the phospholipid molecules by the degree of unsaturation of their fatty acid moieties.) We found that approximately 65% of the [3H]methyl incorporated into phosphatidylcholine during the incubation period was present in the fraction associated with pentaene or hexaene fatty acids; an additional 30% was present in the tetraene fraction, while the remaining phosphatidylcholine radioactivity was distributed between the dienes and monoenes. Similar distributions were observed among synaptosomes incubated for 10 or 30 min; however, after 90 min the phosphatidyl[3H]choline contained proportionately less of the tetraenes. These observations indicate that neuronal phosphatidylcholine molecules formed via N-methylation are especially richer in polyunsaturated fatty acids, and they raise the possibility that these molecules constitute a distinct pool with particular physiologic functions.

Animals↗