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Biomedical subjects

R Schiavon

Publications and source records attributed to R Schiavon.

At least 19 recordsLinked to original sources

Hyperferritinaemia without iron overload: pathogenic and therapeutic implications.

It is not unusual to meet increased levels of ferritinaemia in patients apparently healthy. Among other causes of hyperferritinaemia, recently was described the Hereditary Hyperferritinemia Cataract Syndrome, a genetic condition characterized by increased serum ferritin values without iron overload and bilateral nuclear cataract, both of early onset. It has been demonstrated that single or double point mutations or deletions in the stem-loop structure of the iron regulatory element (I.R.E.) located in the 5 untranslated regions of the ferritin L-subunit gene (19q13.1) are responsible for the upregulation of ferritin. This overexpression only for the L-chain gives rise to typical piles in several tissues. When this altered ferritin accumulates in lens it causes bilateral nuclear cataracts, that is the peculiar sign of this syndrome. It is essential to differentiate true iron overload from Hereditary Hyperferritinaemia Cataract Syndrome (H.H.C.S.), because these patients rapidly develop iron deficient anaemia when venosectioned. Here we describe a case report about a 40 years old healthy female blood donor who presented isolated hyperferritinaemia without iron overload, in the absence of concomitant pathologies. Anamnestic, biochemical, instrumental and clinical investigations led us to diagnose H.H.C.S., a pathology first described in 1995. From 1995 to date about 40 cases concerning patients showing the characteristics of this syndrome from Europe, USA, and Australia were described. Biochemical, genetical and clinical investigations led finally to understand every matter of this pathology, providing conclusive and exhaustive explanations.

Animals↗

On the mechanisms of action of short-term levonorgestrel administration in emergency contraception.

The effects of short-term administration of levonorgestrel (LNG) at different stages of the ovarian cycle on the pituitary-ovarian axis, corpus luteum function, and endometrium were investigated. Forty-five surgically sterilized women were studied during two menstrual cycles. In the second cycle, each women received two doses of 0.75 mg LNG taken 12 h apart on day 10 of the cycle (Group A), at the time of serum luteinizing hormone (LH) surge (Group B), 48 h after positive detection of urinary LH (Group C), or late follicular phase (Group D). In both cycles, transvaginal ultrasound and serum LH were performed from the detection of urinary LH until ovulation. Serum estradiol (E2) and progesterone (P(4)) were measured during the complete luteal phase. In addition, an endometrial biopsy was taken at day LH + 9. Eighty percent of participants in Group A were anovulatory, the remaining (three participants) presented significant shortness of the luteal phase with notably lower luteal P4 serum concentrations. In Groups B and C, no significant differences on either cycle length or luteal P4 and E2 serum concentrations were observed between the untreated and treated cycles. Participants in Group D had normal cycle length but significantly lower luteal P4 serum concentrations. Endometrial histology was normal in all ovulatory-treated cycles. It is suggested that interference of LNG with the mechanisms initiating the LH preovulatory surge depends on the stage of follicle development. Thus, anovulation results from disrupting the normal development and/or the hormonal activity of the growing follicle only when LNG is given preovulatory. In addition, peri- and post-ovulatory administration of LNG did not impair corpus luteum function or endometrial morphology.

Adult↗

Homocysteine as a cardiovascular risk factor.

UNLABELLED: Hyperhomocysteinemia (HH), a known risk factor for vascular diseases, is a frequent condition in hemodialysis (HD) patients. HH induces an oxidant stress to the vascular endothelium, causing a failure of vasodilation and an impairment of the antithrombotic properties. Vitamins B(6), B(12) and folic acid are important cofactors for the enzymes in the catabolism of homocysteine (Hcy). Failure of Hcy catabolism forces the cell to export Hcy into the plasma. The kidney is an important metabolic site for removal (up to 70%) of plasma Hcy (P-Hcy). HD lowers the P-Hcy concentration by 29 and 41% with cellulosic and noncellulosic membranes, respectively, yet values return to normal in only a few patients. Clearly, we must decrease the dangerous high levels of Hcy in different ways. Vitamin Supplementation: Vitamins B(6), B(12) and folic acid decreased the basal level of Hcy by about 40%, starting from the sixth month. Membranes: Some membranes performed better than the others. TECHNIQUES: On the chronic basis, in our 1-year experience, paired filtration dialyis led to the best results, when compared to bicarbonate dialysis and acetate-free biofiltration. Finally, as in HD patients no one type of treatment can normalize the P-Hcy concentration, we should try other, different strategies such as absorption, the use of liposomes and new types of supplementation.

Cardiovascular Diseases↗

Plasma levels of apolipoprotein E and genetic markers in elderly patients with Alzheimer's disease.

Besides apolipoprotein E (APOE) polymorphism, whose association with Alzheimer's disease (AD) has been confirmed in most of the numerous population samples studied, other markers have been investigated. In most cases the association firstly described was not confirmed in subsequent works. Since it is important to examine these associations in as many populations as possible, we investigated APOE, APOC1, APOC2, alpha-1 antichymotrypsin (ACT) and presenilin-1 (PS-1) polymorphisms in a series of elderly patients with late-onset sporadic AD from Northern Italy and in a sex and age-matched control group. We could not confirm the significantly higher frequency of the ACT*A allele among carriers of APOE e*4 allele described elsewhere, although a similar trend was observed. The APOC2 and the PS-1 distributions were similar between patients and controls. However, we observed a significant difference in the genotype and allele frequencies of APOE and APOC1: patients had higher e*4 and C1*2 allele frequencies. This finding confirms the important role for APOE in AD occurrence. In addition, APOC1 seems to be an interesting marker because, though in strict linkage disequilibrium with APOE, it seems to play an independent role in AD risk. In contrast to previously reported data, plasma apoE concentrations were similar in patients and in controls. An interaction between APOE and APOC1 polymorphisms and apoE levels was observed in patients: subjects carrying the APOE E3/E2 or the APOC1 2-2 genotype have higher apoE concentrations than those who do not.

Aged↗

Emergency contraception in Mexico City: what do health care providers and potential users know and think about it?

Emergency contraception promises to reduce Mexico's high unwanted pregnancy and unsafe abortion rates. Because oral contraceptives are sold over-the-counter, several emergency contraceptive regimens are already potentially available to those women who know about the method. Soon, specially packaged emergency contraceptives may also arrive in Mexico. To initiate campaigns promoting emergency contraception, we interviewed health care providers and clients at health clinics in Mexico City, ascertaining knowledge, attitudes, and practices concerning the method. We found limited knowledge, but nevertheless cautious support for emergency contraception in Mexico. Health care providers and clients greatly overestimated the negative health effects of emergency contraception, although clients overwhelmingly reported that they would use or recommend it if needed. Although providers typically advocated medically controlled distribution, clients believed emergency contraception should be more widely available, including in schools and vending machines with information prevalent in the mass media and elsewhere.

Adolescent↗

An overview of haemodialysis and oxidant stress.

Today's patient population is increasingly older. Patients with chronic renal failure therefore start extracorporeal substitutive treatment having congestive heart failure, chronic liver disease, diabetes and so forth. In these patients, however, long-term haemodialytic treatment may add further aggravation on their pre-existing pathological conditions. Oxidative stress and alterations in lipid metabolism are caused by haemodialysis mainly due to (1) bioincompatibility type of reactions such as production of reactive oxygen species by inflammatory cells due to complement-mediated or -independent pathways, and (2) the imbalance between oxidants and antioxidants due to the diffusive loss of hydrophilic vitamins such as ascorbic acid. The events related to the oxidant stress may sustain a state of chronic inflammation. Recent advances suggest that atherosclerosis and proliferation of the smooth muscle are initiated and sustained by inflammatory mechanisms. Therefore, attempts to counterbalance the prooxidant effect of haemodialysis and to reduce the chronic inflammatory state will be presented.

Cardiovascular Diseases↗

A reliable endocrine test with human menopausal gonadotropins for diagnosis of true hermaphroditism in early infancy.

In true hermaphroditism diverse phenotypes and karyotypes are found; there are no distinctive laboratory features that can distinguish it from other intersex disorders, thus the diagnosis is made by the histological findings. Existence of Leydig cells is demonstrated by testosterone levels above the female range; however, presence of ovarian tissue cannot be ascertained because of the absence of a reliable functional test. Unless appropriate biopsies are performed or the whole gonad is removed, there is a risk of not diagnosing true hermaphroditism. To find a reliable test that can differentiate patients with true hermaphroditism from those with other intersex disorders, we investigated the estradiol (E2) response to human menopausal gonadotropins (hMG) in infants with genital ambiguity. These results were correlated with the histological findings. Eleven infants with genital ambiguity and four with a high scrotal testis were stimulated every 12 h with 2 IU/kg hMG. If E2 rose above 80 pg/mL (cut-off point), the test was discontinued; if after 7 days E2 remained below 80 pg/mL, the hMG dose was doubled and stimulation extended for 7 additional days. In five patients in whom true hermaphroditism was later histologically demonstrated, E2 rose above 80 pg/mL. In two of them, ovarian tissue was removed and hMG stimulation repeated; no response above our cut-off point was observed during the second test. The maximal E2 response to hMG in the remaining 10 individuals was 43 pg/mL; after laparotomy or gonadal biopsies no ovarian tissue was found. The hMG stimulation test can be considered a reliable and safe dynamic procedure for demonstrating the presence or absence of ovarian tissue in infants with genital ambiguity.

Adolescent↗

Serum paraoxonase activity is decreased in uremic patients.

Paraoxonase is a high-density lipoprotein (HDL)-associated enzyme capable of hydrolysing lipid peroxides. We measured the activity of serum paraoxonase together with serum concentrations of a variety of lipid constituents--total cholesterol, high-density lipoprotein (HDL) and low-density lipoprotein (LDL), cholesterol, triglycerides, apolipoproteins A-I and B--in 60 hemodialyzed (HD) patients. We found that the paraoxonase activity was significantly reduced in HD patients compared with 64 healthy controls (mean median and interquartile values: 93, 63, 87 IU/l in HD patients and 151, 120 and 135 IU/l in controls). In patients, the trimodal frequency of distribution of paraoxonase activity showed a shift toward lower levels. The effect of NaCl on enzyme activation was more pronounced in the patient group, as compared with controls, suggesting a higher frequency of the B allozyme (more responsive to NaCl) in this population. We suggest that altered HDL subfraction, present in HD patients, may be the main cause of the widespread depression of paraoxonase. Furthermore, the higher frequency of allozyme B among HD patients might increase the risk of coronary artery disease. In conclusion, paraoxonase activity may be an adjunctive index of altered lipoprotein metabolism with important repercussions on atherosclerosis.

Adolescent↗

Plasma factor VII and its relation to adipose tissue fatty acids and other atherogenic risk factors in healthy men.

In this study the authors examined the relationships of plasma factor VII (F-VII) to adipose tissue fatty acid composition, as an objective index of the habitual dietary fat intake, as well as to a number of other atherogenic risk factors in 60 healthy male volunteers (aged 38 years). Significant positive correlations were found between plasma F-VII [measured as antigen (F-VIIAg) and coagulant activity, using bovine thromboplastin (F-VIIbt)] and body mass index (BMI), waist-thigh girth ratio (WTR), cigarette smoking and plasma triglyceride concentration. After adjustment for BMI, only plasma triglycerides remained positively correlated with F-VII (r = 0 center dot 27, P = 0 center dot 03, and r = 0 center dot 29, P < 0 center dot 01, for F-VIIbt and F-VIIAg respectively). A significant positive relation was found between F-VII and the total proportion of fatty acid as monounsaturated fatty acid (r = 0 center dot 26, P < 0 center dot 05, for F-VIIAg), whereas inverse relations were found between F-VII, the total proportion of fatty acid as polyunsaturated fatty acid (r = -0 center dot 26 and r = -0 center dot 25, P < 0 center dot 05, for F-VIIbt and F-VIIAg respectively), polyunsaturated-saturated fat ratio (r = -0 center dot 25, P < 0 center dot 05, for F-VIIbt) and, more significantly, between F-VII and adipose-tissue alpha-linolenic acid (r = -0 center dot 29, P < 0 center dot 01, for F-VIIbt and r = -0 center dot 49, P < 0 center dot 001, for F-VIIAg). All these correlations remained significant after matching for BMI. In a multiple linear regression analysis, only adipose tissue alpha-linolenic acid was a negative and independent predictor of F-VIIAg (P = 0 center dot 004) and, at borderline significance, of F-VIIbt (P = 0 center dot 061) when allowance was made for BMI, WTR, smoking and plasma triglycerides. In conclusion, this study shows significant relations between F-VII and adipose tissue fatty acid composition in healthy male individuals; it supports the possibility that adipose tissue poly-unsaturated fatty acids, derived from dietary intake, play a role in the relation between F-VII and coronary heart disease (CHD), thus suggesting that high dietary polyunsaturated fatty acid intake (especially alpha-linolenic acid) may reduce the risk for CHD by an improvement of a number of risk factors, including a lowering of plasma F-VII (both activity and antigen).

Adipose Tissue↗

Relationships of blood pressure to fibrinolysis: influence of anthropometry, metabolic profile and behavioural variables.

OBJECTIVE: To investigate the relationship between blood pressure and the plasma fibrinolytic system and to verify whether this association was independent or mediated by one or more potential confounding factor. DESIGN: A random sample of 94 males aged 38 years subdivided into normotensives, hypertensives and those hypertensives with the highest blood pressure values. METHODS: Overall and regional obesity, blood lipids, fasting and 2-h post-load glucose, C-peptide and insulin levels, and main behavioural variables, including adipose tissue fatty acid composition (an objective index of dietary fat intake), were measured. The plasma fibrinolytic system was evaluated by determining activities and total plasma concentrations of both tissue-type plasminogen activator before and after venous occlusion, and its inhibitor plasminogen activator inhibitor type-1 (PAI-1). RESULTS: PAI-1 activity was significantly higher in the hypertensives than in the normotensives. PAI-1 antigen tended to parallel PAI-1 activity, and levels of tissue-type plasminogen activator antigen and activity tended to be lower in the hypertensives at baseline and after venous occlusion, but not significantly different from those in the normotensives. The hypertensives also had significantly higher body mass index and body fat content (measured by bio-impedance), increased plasma triglycerides, uric acid, fasting and 2-h glucose, C-peptide and insulin concentrations. In univariate linear regression analysis both systolic and diastolic blood pressures were found to be positively correlated with PAI-1 levels (r = 0.27, P < 0.01, for both). This correlation was maintained after adjustment for total body fat, fasting glucose, fasting insulin concentration or adipose tissue alpha-linolenic acid; however, it was no longer significant after adjustment for plasma 2-h insulin, 2-h C-peptide, 2-h glucose or triglyceride levels. Multivariate regression analysis revealed that only 2-h insulin and triglyceride concentration showed an independent association with PAI-1 levels. CONCLUSIONS: This study confirms that, in 38-year-old males, hypertension is associated with increased PAI-1 activity. It supports the possibility that the relationship between blood pressure and PAI-1 may reflect the overall effect of the insulin resistance syndrome (in particular hyperinsulinaemia and hypertriglyceridaemia) rather than a direct effect of blood pressure on the fibrinolytic system.

Adult↗

Relationships of plasminogen activator inhibitor-1 to anthropometry, serum insulin, triglycerides and adipose tissue fatty acids in healthy men.

Increased plasma levels of plasminogen activator inhibitor-1 (PAI-1), responsible for reduced fibrinolytic activity, have been shown to be an important risk factor for cardiovascular disease. PAI-1 plasma levels are influenced by several factors which have not yet been fully clarified, including dietary fat intake. The relationships of PAI-1 with other cardiovascular risk factors are still not well known. In a random sample of 38-year-old healthy men (n = 94), the association of PAI-1 plasma levels (measured as activity and antigen) with anthropometric parameters, serum lipids, fasting and 2 h insulin and glucose concentration after oral glucose-load was analysed. Furthermore, the fatty acid composition of subcutaneous adipose tissue, as an objective and reliable index of dietary fat intake, was measured. The univariate analysis showed that plasma levels of PAI-1 were significantly associated with body mass index (BMI) (r = 0.37, P < 0.001), waist/hip ratio (WHR) (r = 0.26, P < 0.01), serum triglycerides (r = 0.47, P < 0.0001), HDL/total cholesterol ratio (r = -0.35, P < 0.001), fasting and 2-h insulin (r = 0.27, P < 0.01 and r = 0.34, P < 0.001) and glucose concentrations (r = 0.25, P < 0.05 and r = 0.28, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

Plasma glutathione peroxidase activity as an index of renal function.

The kidney is a major source of the plasma enzyme glutathione peroxidase. We measured plasma glutathione peroxidase activity in 130 patients affected with different renal diseases at various stages, and compared it with the following indices of kidney function: serum creatinine, creatinine clearance, and urinary excretion of alpha 1-microglobulin, beta 2-microglobulin, albumin and N-acetyl-beta-D-glucosaminidase. Plasma glutathione peroxidase activity appeared significantly reduced in most of the renal diseases considered, and showed a significant correlation with most of the renal function indices. Linear discriminant analysis showed that the set of indices composed of plasma glutathione peroxidase activity, serum creatinine and creatinine clearance allowed the best classification of renal diseases. During treatment with the nephrotoxic aminoglycoside, tobramycin, plasma glutathione peroxidase activity showed an early and progressive decrease. We suggest the measurement of plasma glutathione peroxidase activity as an adjunctive index for the assessment of kidney alterations.

Acetylglucosaminidase↗

[Metabolic aspects of intestinal urinary diversion. Comparison with ileo-cecal bladder substitution and ileal conduct].

The aim of this study was the metabolic evaluation of 10 patients with 2 different types of urinary diversions, after cystectomy for infiltrating carcinoma. The patients were divided into two groups, homogeneous for age and follow up, according to the type of urinary diversion: group A (5 patients with ileo-cecal bladder) and group B (5 patients with ileal conduit). The follow up duration was 16.8 +/- 7.3 months in group A and 25.4 +/- 7.8 months, in group B. Even though the glomerular filtration rate (GFR) in both groups was within the normal limits, however - on closer evaluation - patients of A group revealed a slight functional damage, shown by reduced creatinine secretion, lower bicarbonatemia and lower urinary acid secretion when compared with ileal conduit patients. According to this study, the ileal conduit seems to be associated with a fairly good metabolic status while the ileo-cecal bladder could require closer clinical-metabolic follow up and bicarbonate supplementation.

Acidosis↗

Risk factors of ischemic cardiac disease in patients on continuous ambulatory peritoneal dialysis.

Elevated plasma levels of fibrinogen, factor VII coagulant activity (F VIIc), and plasminogen activator inhibitor (PAI-1) have been reported to be strictly associated with thrombotic events and are considered to be important risk markers of atherothrombotic cardiovascular disease. Therefore, we evaluated in 15 patients on continuous ambulatory peritoneal dialysis (CAPD) the plasma levels of these coagulation factors, basal insulin values, and the lipid pattern in comparison with 33 hemodialysis (HD) patients and 59 healthy subjects. In CAPD the total cholesterol and triglyceride results were significantly increased, but no difference was found in HDL cholesterol. Fibrinogen and F VIIc results were significantly higher in CAPD and HD than in the control group, probably due to an increased hepatic synthesis as a nonspecific response to the peritoneal protein loss. Elevated F VIIc activity may be caused by the presence of large negatively charged lipoproteins, in vivo thrombin formation, or reduced hepatic clearance. Both PAI 1 and t-PA results were higher in CAPD, probably due to an increased synthesis by endothelial cells activated by glucose peritoneal absorption and hypertonic dialysis solutions. The contemporary elevation of fibrinogen, F VIIc, PAI-1, and t-PA suggests that CAPD patients present a hypercoagulability and hypofibrinolysis condition, which may promote the development of atherothrombotic events.

Adult↗

Use of purified dermatan sulfate for heparin cofactor II (HC II) assay.

HC II functional assays are generally preferred with respect to immunochemical assays. Nevertheless functional assays can be biased by the antithrombin III (AT III)-heparin complex activity; in fact trace amounts of heparin generally contaminate dermatan sulfate (DS) commercial preparations used as HC II reaction activators. We have employed a purified DS preparation showing these features: DS concentration 94.4%, chondroitin sulfate 5.6%, M.W. 21.4 kDa. The absence of any interference due to AT III-heparin complexes was verified in a kinetic HC II assay of some human plasma pools. The immunological inhibition of AT III by anti-AT III caused a minimal decrease (6-8%) of the reaction slope, attributable to AT III activity. Progressive increase of heparin concentration in the assay was effective only starting from 30 U/ml (the assay was carried out in the presence of polybrene to prevent any AT III activation). The reference interval (mean +/- SD) obtained from 157 normal subjects was 100.8 +/- 20.2%; there was a good correlation with immunoreactive HC II. The purified DS we have used seems suitable for routinary assays of HC II where a minimal interference due to AT III-heparin is required.

Amino Acid Sequence↗