Biomedical subjects

L Mazzanti

Publications and source records attributed to L Mazzanti.

At least 55 records · Page 3Linked to original sources

PubMed1999

Tyrosine phosphorylation in type-1 diabetes by immunogold detection: an in vitro human aortic endothelial cell (HAEC) study in the presence of diabetic low density lipoproteins (LDL).

An immunomorphometric study of tyrosine phosphorylation was performed by the immunogold technique on cultured human aortic endothelial cells (HAEC) with a view to demonstrating their impaired signal transduction status, induced in vitro by incubation with low-density lipoproteins from the plasma of Type-1 diabetic patients. The results seem to sustain the hypothesis that extranuclear bioenergetic derangement induced by low-density lipoproteins from Type-1 diabetic patients may be associated with an up-regulation of the nuclear energetic machinery aimed at maintaining intracellular metabolic equilibrium. Our data demonstrate that phosphorylated tyrosine is a useful marker to monitor this metabolic condition.

Cell Line↗

PubMed1998

Barber-Say Syndrome: report of a new case.

We present a girl with lax, redundant skin, ectropion, bulbous nose, macrostomia, and absence of mammary glands. To our knowledge, she represents the fourth described case of Barber-Say Syndrome (BSS). BSS and ablepharon macrostomia syndrome (AMS) share common and distinctive clinical manifestations that involve the same structure of the skin and adnexa. We hypothesize that they may derive from a defective regulation of the same gene.

Abnormalities, Multiple↗

PubMed1998

Binding of pyrene isothiocyanate to the E1ATP site makes the H4-H5 cytoplasmic loop of Na+/K+-ATPase rigid.

1-Pyreneisothiocyanate was shown to be an inhibitor of Na+/K+-ATPase. Reverse-phase HPLC and activity studies indicated binding of 1-pyreneisothiocyanate at the H4-H5 loop of the alpha subunit and competition with the fluorescein 5'-isothiocyanate for the E1ATP site. While fluorescein 5'-isothiocyanate, the fluorescent ATP pseudo-analog, was shown to be immobilized at the E1ATP site, there was no possibility to draw any conclusion about the flexibility of the E1ATP site due to its short lifetime. Employing 1-pyreneisothiocyanate as a long-lived fluorophore and a label for the E1ATP site, we found that the ATP-binding site of Na+/K+-ATPase and, in fact, the whole large intracellularly exposed H4-H5 loop of the catalytic alpha subunit is rigid and rotationally immobilized. This has important consequences for the molecular mechanism of the transport function.

Adenosine Triphosphate↗

PubMed1998

Decreased nitric oxide synthase activity in platelets from IDDM and NIDDM patients.

Nitric oxide (NO) produced by platelet nitric oxide synthase (NOS) inhibits platelet activation by increased cytoplasmic cGMP levels. The aim of this study was to investigate platelet NOS activity in insulin-dependent (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM), which are characterized by enhanced platelet activation. HbA1c levels, platelet NOS and platelet membrane Na+/K+ ATPase activity were determined in 19 IDDM patients, 21 NIDDM patients and 31 healthy control subjects. NOS activity was measured by a spectrophotometric method based on NO-dependent oxidation of oxyhaemoglobin to met-haemoglobin. Na+/K+ ATPase activity was measured by the method of Kitao and Hattori. Both NOS and Na+/K+ ATPase activity were significantly reduced in diabetic subjects compared with control subjects. NOS showed a significant negative relation with HbA1c levels and a positive relation with Na+/K+ ATPase activity in diabetic patients. It is hypothesized that the decreased NOS activity might play a role in the pathogenesis of diabetic vascular complications.

Adult↗

PubMed1998

Congenital heart disease in patients with Turner's syndrome. Italian Study Group for Turner Syndrome (ISGTS).

OBJECTIVE: There is a high prevalence of congenital heart defects in patients with Turner's syndrome. Few studies have reported echocardiographic data in unselected patients according to the different chromosomal patterns. The aim of our study was to evaluate a large series of patients with Turner's syndrome, comparing these data with those of the general population. METHODS: Five hundred ninety-four patients with Turner's syndrome, aged 1 month to 24 years, in the Italian Study Group for Turner Syndrome underwent full cardiologic evaluation. Karyotype distribution was: 45,X (54%), X-mosaicism (13%), and X-structural abnormalities (33%). RESULTS: The prevalence of cardiac malformations was 23%. Bicuspid aortic valve (12.5%), aortic coarctation (6.9%), and aortic valve disease (3.2%) were the most prevalent malformations. In comparison with the general population, partial anomalous pulmonary venous drainage had the highest relative risk. A correlation was found between type of congenital heart defect and karyotype. The patients with 45,X karyotype had the greatest prevalence of partial anomalous pulmonary venous drainage and aortic coarctation, whereas bicuspid aortic valve and aortic valve disease were more common in the patients with X-structural abnormalities. The patients with severe dysmorphic signs showed a significantly higher relative risk of cardiac malformations. CONCLUSION: X-linked factors may be involved in determining cardiac defects in Turner's syndrome.

Adolescent↗

PubMed1998

Gestational hypertension plasma and human umbilical vein endothelial cells: an in vitro study.

BACKGROUND: The action of plasma from women affected by gestational hypertension (GH) on nitric oxide synthase (NOS) activity in cultured human umbilical vein endothelial cells (HUVECs) was evaluated in the present study, together with the effect on cytosolic calcium, on Na+, K+-ATPase activity and on membrane fluidity. METHODS: At 80% confluence, cultured HUVECs were incubated for 3 h at 37 degreesC with fresh culture medium (control samples) or with 20% (v/v) plasma (from five healthy non-pregnant women, five healthy pregnant women and five pregnant women affected by GH). RESULTS: After incubation with GH plasma, we observed a significant reduction in NOS activity, intracellular calcium concentrations and Na+, K+-ATPase activity. CONCLUSIONS: The present work gives further support to the hypothesis that a circulating factor in gestational hypertension, possibly produced by the fetoplacental unit, causes dysfunction of the vascular endothelial cells and NO reduction, resulting in a loss of vascular refractoriness to vasoactive agents.

Adult↗

PubMed1998

Growth retardation and discordant twin pregnancy. An immunomorphological and biochemical characterisation of the human umbilical cord.

Growth retardation and low birth weight represent an important factor associated with the high risk of mortality and morbidity, particularly in twin pregnancy, since twins are frequently characterised by fetal growth retardation and sometimes by a discordant growth between the twins. The present work sets out to elucidate the role of growth discordance between twins in the behaviour of human umbilical vein endothelial cells; biochemical, ultrastructural and immunohistochemical data obtained from a discordant twin pregnancy are discussed. Endothelial cells were obtained from umbilical cord of 5 singleton pregnancies and from 5 dichorionic twin pregnancies, among which was one discordant twin pregnancy. Membrane fluidity was assayed using a fluorescent probe and each sample was immunohistochemically processed employing specific monoclonal antibodies. An increased fluidity was observed in endothelial cells from the smaller twin as compared with the larger one. As concerns electron microscopy, the features of endothelial cells from the smaller twin were similar to those of twins with similar growth, while endothelial cells from the larger one were more similar to those from singleton pregnancies. Our findings confirm the presence of the feto-fetal transfusion as a pathogenetic mechanism involved in twin growth discordancy.

Adult↗

PubMed1998

Biochemical modifications of human whole saliva induced by pregnancy.

OBJECTIVE: To assess human unstimulated whole saliva components during pregnancy, to determine the relation, if any, between pregnancy and oral health, particularly total protein concentration, alpha-amylase activity, sialic acid content and calcium and phosphate concentrations were evaluated. DESIGN: Cross-sectional study. PARTICIPANTS: Forty-five healthy primigravid women; 15 nonpregnant women acted as controls. RESULTS: 1. A higher total protein content at 10 and 21 weeks of gestation with respect to the controls and to pregnant women at 40 weeks; 2. a higher alpha-amylase activity at 10 and 21 weeks of gestation compared with the controls and to pregnant women at 40 weeks; 3. an increased sialic acid content at 21 and 40 weeks; 4. decreased calcium and phosphorus concentrations at 21 and 40 weeks of gestation. CONCLUSIONS: Pregnancy modifies saliva composition. This could play a pivotal role in the incidence of pregnancy-induced dental caries.

Adult↗

PubMed1998

Outcome of premature thelarche: relation to puberty and final height.

BACKGROUND: There is a debate about the possible progression of idiopathic premature thelarche towards precocious or early puberty. OBJECTIVE: To evaluate height and age at onset of puberty in a group of girls with a history of idiopathic premature thelarche. STUDY DESIGN: The height and age at onset of puberty of 42 girls now over 10 years of age who were diagnosed with isolated premature thelarche before the age of 3 years were evaluated. RESULTS: Menarche was reached before or at 11 years of age in 13.5% of this group of girls. This percentage of early menarche was higher than would be expected from historical controls in the general population, but was consistent with maternal age of menarche. The mean (SD) height of the girls (n = 15) who achieved adult height was 162.9 (6.3) cm, which was slightly higher than the mean (SD) relative mid-parental height (160.7 (6.7) cm). CONCLUSIONS: Isolated premature thelarche with onset before 3 years of age progresses towards precocious puberty, although this was consistent with the maternal age of menarche. Furthermore, adult height was normal when compared with population norms in all patients.

Adolescent↗

PubMed1998

Modifications induced by plasma from insulin-dependent diabetic patients and by lysophosphatidylcholine on human Na+,K(+)-adenosine triphosphatase.

To investigate the molecular mechanisms of the inhibition of Na+,K(+)-adenosine triphosphatase (Na+,K(+)-ATPase) in diabetes mellitus, we incubated Na+,K(+)-ATPase purified from human placenta of six healthy nondiabetic women with plasma from six insulin-dependent diabetic (IDDM) men and six healthy controls and with different concentrations of lysophosphatidylcholine (LPC). We determined the enzyme activity, anthroyl ouabain-binding capacity, dissociation constant (Kd), and average lifetime values (tau) by the static and dynamic fluorescence of anthroyl ouabain. The lipid annulus of the enzyme was studied by static and dynamic fluorescence of 1-(4-trimethylamino-phenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH). Moreover, we studied the lipid microenvironment surrounding the Na+,K(+)-ATPase purified from the placentas of six healthy women and six insulin-dependent diabetic women, determining the percent composition of phospholipids of the lipid annulus. The addition of total and protein-free IDDM plasma to normal Na+,K(+)-ATPase significantly inhibited the enzymatic activity even at the lowest concentration studied (1: 100), whereas the ouabain-binding capacity, Kd, and tau were not affected by IDDM plasma. The fluorescence polarization and lifetime values of TMA-DPH were significantly decreased by diabetic plasma. The incubation of Na+,K(+)-ATPase with LPC caused an inhibition of the enzymatic activity without modifications of the anthroyl ouabain-binding capacity and dissociation constant. The fluorescence polarization and lifetime values of TMA-DPH were significantly decreased by 5 mumol/L LPC. The study of the phospholipids surrounding Na+,K(+)-ATPase demonstrated a significant increase in the percent LPC content in IDDM patients compared with controls together with a concomitant decrease in phosphatidylcholine. These observations indicate that the inhibition caused by diabetic plasma on Na+,K(+)-ATPase is not dependent on a modification of the ouabain-binding site and that it seems to mimic the effect of LPC addition. A link between modification of the lipid moiety of the enzyme and Na+,K(+)-ATPase inhibition might be hypothesized.

Adult↗

PubMed1997

High-level expression of a cDNA for human granulocyte colony-stimulating factor in Chinese hamster ovary cells. Effect of 3'-noncoding sequences.

We compared the production of recombinant human granulocyte colony-stimulating factor (rhG-CSF) by Chinese hamster ovary (CHO) cells in a transient expression system, using different analogous vectors carrying a human G-CSF-encoding cDNA under the transcriptional control of the murine cytomegalovirus (CMV) major immediate early promoter. Comparison of two transcription units carrying a human (h)G-CSF cDNA deleted of 3'-untranslated (UTR) sequences containing AT-rich elements (ARE) and using 3'-UTR sequences for processing of transcripts from the SV40 early region or from the rabbit beta 1-globin gene showed that use of the sequences from the rabbit beta 1-globin gene resulted in 7- to 12-fold higher levels of rhG-CSF production. Deletion of ARE of hG-CSF cDNA resulted in increased rhG-CSF synthesis when transcription units using 3'-UTR sequences from the rabbit beta 1-globin gene were compared. By contrast, deletion of ARE did not appear to affect rhG-CSF production when 3'-UTR sequences from the SV40 early region were used. The most efficient G-CSF transcription unit, fused to a dihydrofolate reductase (DHFR) marker gene and transfected into a CHO cell line, yielded initial transfectant CHO cell lines secreting up to 21 micrograms rhG-CSF/1 x 10(6) cells in 24 h. After two rounds of DHFR gene amplification, a cell line was isolated that contains approx 12 copies of the vector and produces rhG-CSF at a rate of 90 micrograms/1 x 10(6) cells in 24 h.

Animals↗

PubMed1997

Diabetes-induced alterations in platelet metabolism.

OBJECTIVES: This review summarizes the recent findings on some aspects of platelet metabolism that appear to be affected as a consequence of diabetes mellitus. The metabolites include glutathione, L-Arginine/nitric oxide, as well as the ATP-dependent exchange of Na+/K+ and Ca2+. CONCLUSIONS: Several aspects of platelet metabolism are altered in diabetics. These metabolic events give rise to a platelet that has less antioxidants, and higher levels of peroxides. The direct consequence of this is the overproduction platelet agonists. In addition, there is evidence for altered Ca2+ and Na+ transport across the plasma membrane. Recent evidence indicates that plasma ATPases in diabetic platelets are not damaged instead their activities are likely to be modulated by oxidized LDL. Finally, platelet inhibitory mechanisms regulated by NO appear to be perturbed in the diabetes disease-state. The combined production of NO and superoxide by NOS isoforms in the platelet could be a major contributory factor to platelet pathogenesis in diabetes mellitus.

Blood Platelets↗

PubMed1997

Modifications induced by insulin-dependent diabetes mellitus on human placental Na+/K+-adenosine triphosphatase.

The causes of the reduced activity of Na+/K+-adenosine triphosphatase (ATPase) in human diabetes are still the object of controversy. The aim of this work was to investigate the mechanisms of inhibition by means of the study of the Na+/K+-ATPase purified from human placenta. We purified Na+/K+-ATPase from term placentas of six healthy women and six age-matched women with insulin-dependent diabetes mellitus (IDDM) in good metabolic control. The enzymatic activity was reduced in both the microsomal fraction and the purified Na+/K+-ATPase obtained from diabetic women, whereas no difference was found in the number of active molecules determined by anthroyl ouabain binding. The Na+/K+-ATPase purified from women with IDDM did not show any modification in the ouabain affinity or changes in the physicochemical structure of the ouabain binding site investigated by dynamic fluorescence or alterations in lateral diffusion. The activation energy of the enzyme was increased, whereas the tryptophan accessibility of the enzyme was lower in women with IDDM. The fluidity of the lipid anulus of the enzyme was higher in women with IDDM than in control women, as suggested by fluorescence polarization of 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5-hexatriene. The adenosine triphosphate-binding site, investigated by anisotropy decay studies of the fluorescent probe pyrene isothiocyanate, was modified in women with IDDM. It appears that the Na+/K+-ATPase of human placenta is altered in its disposition in IDDM.

Acrylamide↗

PubMed1997

Pelvic ultrasonography in patients with Turner syndrome: age-related findings in different karyotypes.

Real-time ultrasonography was performed in 142 patients with Turner syndrome, aged 0.57 to 21 years, with different karyotypes (45,X [4896], X mosaicism [17%], and X structural abnormalities [35%]). Ovarian and uterine volumes were calculated and the data collected in a mixed longitudinal and cross-sectional mode. Thirty-eight patients were followed longitudinally during pubertal age (10 to 18 years bone age) for ovarian data. Patients with Turner syndrome were divided into two groups according to the presence or absence of detectable ovaries. Patients with Turner syndrome with detectable ovaries showed the first increase in ovarian volume at about 9 years of bone age; this increase was continuous and more evident only after 14 years of age and appeared later than in control subjects. When followed longitudinally during puberty, the ovaries showed a hormonal function in some cases. Girls with X mosaicism had the highest percentage of bilateral detectable ovaries and the greatest total ovarian volume; about 50% of them had spontaneous breast appearance and 38.5% had spontaneous menarche. They showed also the lowest gonadotropin levels, when bilateral ovaries were present during puberty. On the contrary, patients with the 45,X karyotype had the lowest percentage of detectable ovaries, ovarian volume, and spontaneous breast appearance. In our patients with Turner syndrome, uterine measures increased significantly with age and this was more evident in subjects with detectable ovaries after 13 years of bone age. Compared with control subjects, they showed significantly lower uterine measures, and patients with X mosaicism had greater and more progressive increments. In conclusion, pelvic ultrasonography in Turner syndrome is particularly useful in detecting ovaries and their possible increase in volume. These data, linked with karyotype pattern and gonadotropin levels, have prognostic value in predicting the future sexual development of these patients.

Adolescent↗

PubMed1997

Sialic acid, diabetes, and aging: a study on the erythrocyte membrane.

Sialic acid (SA) content and Na+/K+-ATPase activity of red blood cell (RBC) membranes were studied in 26 normoalbuminuric patients with insulin-dependent diabetes mellitus (IDDM), 25 normoalbuminuric patients with non-insulin-dependent diabetes mellitus (NIDDM), and 40 healthy nondiabetic subjects with a negative family history for diabetes. A decrease in RBC membrane SA content and Na+/K+-ATPase activity was observed in older control subjects compared with younger controls. A significant correlation between age, Na+/K+-ATPase activity, and SA content was also found. No difference was observed in RBC membrane SA content between IDDM and NIDDM subjects, but Na+/K+-ATPase activity was significantly lower in IDDM patients. SA content was increased in NIDDM subjects compared with healthy subjects of similar age, whereas Na+/K+-ATPase activity was significantly lower in both IDDM and NIDDM subjects compared with controls. In NIDDM, Na+/K+-ATPase activity was significantly correlated with age, whereas both Na+/K+-ATPase activity and SA content were significantly correlated in IDDM and NIDDM patients. Hemoglobin A1c, (HbA1c) levels did not show any significant correlation either with Na+/K+-ATPase or with SA content in diabetic patients. The modified SA content and Na+/K+-ATPase activity in elderly subjects described in the present study indicate a similar behavior of the erythrocyte membrane during both RBC senescence and aging of subjects.

Adolescent↗

PubMed1997

Modifications induced by plasma of gestational hypertensive women on the Na+/K+-ATPase obtained from human placenta.

In order to investigate the molecular mechanisms of the inhibition of Na+/K+-ATPase in Gestational Hypertension (GH), we incubated Na+/K+-ATPase purified from human placenta of 6 healthy normotensive women with plasma from 6 GH women and 6 healthy controls. We determined the enzyme activity by the method of Esman, and the anthroyl-ouabain-binding capacity, dissociation constant (Kd) and average lifetime values (tau) by the static and dynamic fluorescence of anthroyl-ouabain. The lipid annulus of the enzyme was studied by static and dynamic fluorescence of 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5- hexatriene (TMA-DPH). The addition of total and protein-free GH plasma to normal Na+/K+-ATPase significantly inhibited the enzymatic activity even at the lowest concentration studied (1:100), as well as the ouabain-binding capacity, Kd and tau. GH plasma significantly decreased the fluorescence polarization and lifetime values of TMA-DPH. These observations indicate that the inhibition caused by GH plasma on Na+/K+-ATPase might be due to a reduction of the number of active molecules or a modification of the ouabain-binding site suggesting the existence of digitalis-like factor. A link between the modification of the lipid moiety of the enzyme and the Na+/K+-ATPase inhibition might be hypothesized.

Adult↗

PubMed1997

Diabetes mellitus and subjects' ageing: a study on the ATP content and ATP-related enzyme activities in human erythrocytes.

Na+/K(+)- and Ca(2+)-ATPase are the major ATP-dependent membrane-bound enzymes that regulate the cation transmembrane gradient which is altered both in red blood cell (RBC) senescence and in RBCs of diabetic patients. In an attempt to clarify the possible connection between diabetes mellitus and ageing, we investigated the relationship between RBC ATP content, Na+/K(+)-ATPase, Ca(2+)-ATPase activities and ageing in healthy, insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) subjects. A significant correlation was found (r = -0.82; P < 0.001) between RBC ATP content and subject's age only in the control group. A significant reduction in Na+/K(+)-ATPase activity was observed in the older group (C2) of control subjects, in comparison with the younger (C1) one. In both IDDM and NIDDM subjects, the enzymatic activity was significantly decreased when compared with health subjects of similar age (P < 0.001). A significant negative correlation was found between age and enzymatic activity in healthy subjects (r = -0.60; P < 0.001). No difference was observed in the RBC membrane Ca(2+)-ATPase activity between younger (C1) and older (C2) healthy subjects. Ca(2+)-ATPase activity was significantly increased both in IDDM patients compared with C1 (P < 0.001) and in NIDDM patients compared with C2 (P < 0.001). The present data indicate that ageing causes a reduction in the erythrocyte ATP content in both healthy and diabetic subjects. In diabetic patients Na+/K(+)-ATPase activity decreases independently of age.

Adenosine Triphosphate↗

PubMed1997

Altered platelet membrane dynamic properties in type 1 diabetes.

A modified platelet response to aggregating stimuli is supposed to play a role in the pathogenesis of diabetic macroangiopathy. We studied the fluidity and microheterogeneity of the external surface of the platelet membrane and the activities of the plasma membrane Na+-K+-ATPase and Ca2+-ATPase in 21 men with type 1 diabetes and in 20 control subjects before and after in vitro thrombin addition. In the resting state, platelets from type 1 diabetic patients showed an increased fluidity and microheterogeneity of the platelet membrane, a higher Ca2+-ATPase activity, and a reduced Na+-K+-ATPase activity in comparison with platelets from healthy subjects. The fatty acid composition was also modified, with increased C 16:1 and decreased C 18:0 content. Control cells incubated with thrombin showed a modification of the membrane parameters opposite to the response observed in type 1 cells after the stimulation. The incubation of control platelets in the resting state with high concentrations of glucose modified the fluidity of the plasma membrane Na+-K+-ATPase and Ca2+-ATPase activities in an opposite way in comparison with the alterations observed in type 1 platelets. This study suggests that in type 1 diabetic patients, the platelet membrane responds to activation with a molecular remodeling different from the response of healthy subjects. The abnormal organization of the membrane might contribute to the altered platelet functions in type 1 diabetic patients, but acute exposure to high glucose levels does not seem able to modify the platelet membrane in the way observed in type 1 diabetes.

Adult↗