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Biomedical subjects

V Bianchi

Publications and source records attributed to V Bianchi.

At least 37 records · Page 2Linked to original sources
PubMed1998

A clinical and haemodynamic investigation into the role of calf perforating vein surgery in patients with venous ulceration and deep venous incompetence.

OBJECTIVE: To determine the clinical efficacy and local haemodynamic effects of perforating vein surgery in ulcerated limbs with combined deep and perforating vein incompetence. DESIGN: Prospective, interventional study. MATERIALS AND METHODS: Seven ulcerated limbs with combined primary deep and perforating vein incompetence were studied. Clinical efficacy was determined by ultimate ulcer healing and reduction in ulcer area, local haemodynamics were assessed at three sites with photoplethysmographic 90% venous refilling times (PPG RT90); both assessments were performed pre- and 1-month postoperatively. RESULTS: None of the ulcers healed following perforating vein surgery, the median (range) ulcer areas pre- and postoperatively were 31 (7-685) cm2 and 35.5 (7-796) cm2 (Wilcoxon p = 0.07). Preoperative PPG RT90 demonstrated a global abnormality of venous function at all sites examined that persisted after perforating vein surgery. CONCLUSION: In the presence of deep venous incompetence perforating vein surgery had no influence on venous function or ulcer healing. We conclude that perforating vein surgery is not indicated for the treatment of venous ulceration in limbs with primary deep venous incompetence.

Aged↗
PubMed1997

Cell cycle-dependent metabolism of pyrimidine deoxynucleoside triphosphates in CEM cells.

We incorporated 3H-labeled thymidine, deoxycytidine, or cytidine into dNTPs and DNA of exponentially growing CEM cells. G1 and S phase cells were separated by centrifugal elutriation, and the size and specific activity of dNTP pools were determined to study the cell cycle-dependent regulation of specific dNTP synthesizing enzymes in their metabolic context. With [3H]thymidine, we confirm the earlier demonstrated S phase specificity of thymidine kinase. Incorporation of radioactivity from [5-3H]deoxycytidine into dCTP occurred almost exclusively in G1 cells. During S phase, de novo synthesis by ribonucleotide reductase was switched on, resulting in a 70-fold dilution of [3H]dCTP, confirming that ribonucleotide reductase is an S phase-specific enzyme, whereas deoxycytidine kinase is not. [5-3H]Cytidine appeared in dCTP almost to the same extent in G1 as in S phase, despite the S phase specificity of ribonucleotide reductase. During S phase, DNA replication greatly increased the turnover of dCTP, requiring a corresponding increase in ribonucleotide reductase activity. During G1, the enzyme maintained activity to provide dNTPs for DNA repair and mitochondrial DNA synthesis. The poor incorporation of isotope from deoxycytidine into DNA earlier led to the suggestion that the nucleoside is used only for DNA repair (Xu, Y-Z., Peng, H., and Plunkett, W. (1995) J. Biol. Chem. 270, 631-637). The poor phosphorylation of deoxycytidine in S phase provides a better explanation.

Cell Line↗
PubMed1997

The three-dimensional structure of flavodoxin reductase from Escherichia coli at 1.7 A resolution.

Flavodoxin reductase from Escherichia coli is an FAD-containing oxidoreductase that transports electrons between flavodoxin or ferredoxin and NADPH. Together with flavodoxin, the enzyme is involved in the reductive activation of three E. coli enzymes: cobalamin-dependent methionine synthase, pyruvate formate lyase and anaerobic ribonucleotide reductase. An additional function for the oxidoreductase appears to be to protect the bacteria against oxygen radicals. The three-dimensional structure of flavodoxin reductase has been solved by multiple isomorphous replacement, and has been refined at 1.7 A to an R-value of 18.4% and Rfree 24.8%. The monomeric molecule contains one beta-sandwich FAD domain and an alpha/beta NADP domain. The overall structure is similar to other reductases of the NADP-ferredoxin reductase family in spite of the low sequence similarities within the family. Flavodoxin reductase lacks the loop which is involved in the binding of the adenosine moiety of FAD in other FAD binding enzymes of the superfamily but is missing in the FMN binding phthalate dioxygenase reductase. Instead of this loop, the adenine interacts with an extra tryptophan at the C terminus. The FAD in flavodoxin reductase has an unusual bent conformation with a hydrogen bond between the adenine and the isoalloxazine. This is probably the cause of the unusual spectrum of the enzyme. There is a pronounced cleft close to the isoalloxazine that appears to be well suited for binding of flavodoxin/ferredoxin. Two extra short strands of the NADP-binding domain probably act as an anchor point for the binding of flavodoxin.

Adenosine↗
PubMed1997

Incremental prognostic value of thallium reinjection after stress-redistribution imaging in patients with previous myocardial infarction and left ventricular dysfunction.

UNLABELLED: This study evaluated the incremental prognostic value of 201TI reinjection imaging over clinical, exercise and thallium stress-redistribution data in patients with previous myocardial infarction and left ventricular dysfunction. METHODS: Thallium-201 reinjection after stress-redistribution SPECT was performed in 104 consecutive patients with a first Q-wave myocardial infarction (> 8 wk) and left ventricular ejection fraction < or = 40%. Follow-up data (mean 22 mo) were available for 98 patients; 16 patients underwent early revascularization procedures within 3 mo after exercise testing and were not considered for the analysis. RESULTS: During follow-up there were 13 hard events (cardiac death and myocardial infarction) and 11 soft events (coronary revascularization procedures > 3 mo after thallium imaging). With multivariate Cox regression analysis, the sum of defects at stress-redistribution imaging that were reversible or moderate irreversible after reinjection was a powerful predictor of subsequent events. The addition of thallium reinjection imaging data significantly improved the prognostic power of clinical, exercise and stress-redistribution data for the occurrence of hard events (p < 0.01). CONCLUSION: In patients with previous myocardial infarction and left ventricular dysfunction, thallium reinjection imaging provides incremental prognostic information over those obtained from conventional stress-redistribution imaging.

Analysis of Variance↗
PubMed1996

Synergistic antiviral action of ribonucleotide reductase inhibitors and 3'-azido-3'-deoxythymidine on HIV type 1 infection in vitro.

Ribonucleotide reductase inhibitors reduce the cellular supply of DNA precursors(dNTP) by interfering with their de novo synthesis. A secondary effect is the stimulation of the uptake and phosphorylation of extracellular deoxynucleosides, including their analogs, e.g., 3'-azidothymidine (AZT). Both effects are relevant to HIV replication, which requires dNTP and is impaired by the triphosphate of AZT. Earlier we demonstrated that ribonucleotide reductase inhibitors--hydroxyurea, and two deoxycytidine analogs specifically active in lymphoid cells--increased the phosphorylation of AZT in CEM cells by prolonging the S phase of the cell cycle. Here we tested the effects of long-term treatments on HIV proliferation in CEM cells and stimulated human lymphocytes infected with HIV-1IIIB. Treatment with low doses of AZT (0.05-0.1 microM) and either hydroxyurea (25-100 microM) or 2'-azido-2'-deoxycytidine (0.25-4 microM) lasted 2 weeks, during which p24 in the culture medium was monitored. Noninfected CEM cells were treated in parallel to measure the inhibition of cell growth, distribution along the cell cycle, dNTP pool size, and level of tritiated AZT phosphorylation. A clear synergism between AZT and ribonucleotide reductase inhibitors was observed at nontoxic doses that induced only minor changes in the cellular parameters measured. The reductase inhibitors by themselves interfered with replication only at doses that inhibited cell proliferation.

Antiviral Agents↗
PubMed1996

Rapid reversed-phase high-performance liquid chromatographic method for the assay of urinary 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid and confirmation of use of cannabis derivatives.

The main active cannabis (marijuana and hashish) derivative delta 9-tetrahydrocannabinol is, in vivo, transformed and excreted mainly as 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) and its glucuronide. The method presented here allows the confirmation of the presence of THC-COOH by means of a basic hydrolysis, solid-phase extraction clean-up on reversed-phase (RP) disposable cartridges followed by analysis on a C8 RP column and UV detection; the mobile phase used was a 55% acetonitrile solution in acid phosphate buffer. Over 600 samples both from drug addicts in therapeutic communities and subjects who were not on any drugs therapy were analysed. This method was precise with a linearity range from 10 to more than 500 ng/ml [the lower limit proposed by the National Institute on Drug Abuse (NIDA) for cannabinoid confirmation method is 15 ng/ml]. The sample preparation is simple and fast, allowing the analysis of large numbers of samples. Perfect correlation was observed between data from the HPLC method and a fluorescence polarization immunoassay screening method. The THC-COOH metabolite was found to constitute 30% of all the cannabinoids excreted in urine of abusers.

Chromatography, High Pressure Liquid↗
PubMed1996

Effect of 1 year of lisinopril treatment on cardiac autonomic control in hypertensive patients with left ventricular hypertrophy.

In this study we evaluated in hypertensive patients the effects of drug-induced left ventricular hypertrophy regression on cardiac autonomic control, as assessed by means of heart period variability analysis. Power spectral analysis of 24-hour electrocardiographic monitoring was performed in 30 hypertensive patients with left ventricular hypertrophy at baseline, after 1 year of lisinopril treatment, and after 1 month of drug withdrawal. At the same times, patients underwent 24-hour blood pressure monitoring, echocardiographic study, and plasma renin activity assessment. Lisinopril treatment increased plasma renin activity and reduced 24-hour systolic and diastolic pressures (from 159 +/- 14 to 121 +/- 8 and from 103 +/- 7 to 80 +/- 3 mm Hg, respectively) and left ventricular mass index (from 159 +/- 33 to 134 +/- 26 g/m2); moreover, in 12 of 30 patients, left ventricular mass normalization was achieved. Drug withdrawal was followed by an increase in blood pressure without left ventricular mass modification. In the total study population, only high-frequency power was higher after lisinopril treatment. In the subgroup of patients with left ventricular mass normalization, daytime and nighttime high-frequency powers as well as nighttime total and very-low-frequency powers were higher after 1 year of treatment than at baseline. In the remaining 18 patients, power spectral measures after treatment were slightly lower than at baseline and were even lower after drug withdrawal. Thus, in hypertensive hypertrophic patients, lisinopril treatment improves sympathovagal imbalance when left ventricular mass normalization is achieved. In patients without left ventricular mass normalization, drug withdrawal is followed by a worsening of neural cardiac control.

Adult↗
PubMed1995

Molecular analysis of mutations in the hprt gene of V79 hamster fibroblasts: effects of imbalances in the dCTP, dGTP and dTTP pools.

dCMP-deaminase-deficient V79/dC hamster cells have highly imbalanced deoxyribonucleoside triphosphate (dNTP) pools, i.e. a 17-fold larger dCTP pool, a slightly reduced dTTP and a very low dGTP pool, compared to dCMP-deaminase-proficient V79/p cells. Nevertheless, the two lines showed the same rates of spontaneous mutation at the hprt and ouabain-resistance loci. Analysis of spontaneous hprt mutations indicated an increase in misincorporation of C in V79/dC cells, although it was not statistically significant. When the dCTP pool was further increased fivefold by incubating V79/dC cells with cytidine, C misincorporation increased to 88%, but the mutation frequency remained unchanged. The dNTP pools of V79/dC cells were also altered by treatment with thymidine, or with thymidine plus deoxycytidine. After incubation with thymidine alone, the dCTP pool all but disappeared, whereas it maintained a normal level in the presence of deoxycytidine. In both cases dTTP rose to nmol amounts, and dGTP accumulated. Incubation with 10 mM thymidine was the only treatment that increased the mutation frequency; T misincorporation then accounted for 94% of the base substitutions. In the presence of deoxycytidine the cells had a dTTP/dCTP ratio of 0.04, but 86% of the base substitutions involved C misincorporation and most probably originated from G mis-incorporation caused by excess dGTP. Alterations of RNA splicing and hot spots for base substitutions varied with the imbalance, the latter showed "next-nucleotide effects". Our results suggest that the fidelity of DNA replication in V79 cells is only affected by large changes in the pool and is more sensitive to changes in dGTP than in dCTP or dTTP.

Animals↗
PubMed1995

Rapid reversed-phase high-performance liquid chromatographic method with double derivatization for the assay of urinary hydroxyproline.

An HPLC method with two derivatizations, the first with o-phthaldehyde in order to eliminate interferences due to some primary amino acids eluting with retention times similar to those of hydroxyproline and the second with dabsyl chloride, was developed and evaluated. Calibration graph linearity, influence of agitation and temperature on the preparation of the first derivative and the influence of the detection wavelength were assessed. The analysis time is shorter in comparison with other available methods, and therefore this method is suitable for laboratories that analyse both small and large series of samples.

Chromatography, High Pressure Liquid↗
PubMed1995

Power spectral analysis of heart period variability in hypertensive patients with left ventricular hypertrophy.

This study aimed to characterize sympathovagal balance by heart period power spectrum analysis in hypertensive patients with echocardiographic evidence of left ventricular hypertrophy. Twenty ambulatory patients (11 men and 9 women), aged 50 +/- 10 years, with established essential hypertension and echocardiographic left ventricular hypertrophy, performed 24-h blood pressure monitoring and electrocardiogram Holter recording on 2 consecutive days. Twenty age- and sex-matched normal subjects comprised the control group. Power spectrum analysis, performed using the fast Fourier transform algorithm, demonstrated lower values of low and high frequency power in hypertensives than in controls, while ultralow and very low frequency power were similar in the two groups. Very low frequency, low frequency, and high frequency power increased during the night in both groups, showing a similar circadian pattern. We found a direct correlation between daytime systolic (r = 0.51; P < .05) and diastolic (r = 0.52; P < .05) blood pressure and left ventricular mass index. Moreover, negative correlations were found between left ventricular mass index and low frequency (r = -0.47; P < .05) and high frequency power (r = -0.47; P < .05). There was a direct correlation between nighttime decrease in systolic blood pressure and nighttime increase in high frequency power (r = 0.45; P < .05). As 24-h low frequency and high frequency power, obtained using the Fourier transform algorithm, both reflect the parasympathetic modulation of heart rate, our results demonstrate that hypertensive patients with left ventricular hypertrophy are characterized by a sympathovagal imbalance with a reduction of vagal tone that is more evident with increasing severity of hypertension.

Blood Pressure↗
PubMed1995

Influence of left ventricular hypertrophy on heart period variability in patients with essential hypertension.

OBJECTIVE: To evaluate whether left ventricular hypertrophy in hypertensive patients is associated with a greater impairment of sympathovagal balance assessed by means of heart period variability. DESIGN AND METHODS: Forty hypertensive patients, 20 with echocardiographic evidence of left ventricular hypertrophy and 20 without, and 20 control subjects, were subjected to 24 h blood pressure monitoring and Holter recording on 2 consecutive days. Power spectrum analyses of heart period variability were performed utilizing the fast Fourier transform algorithm. RESULTS: No difference was detectable in 24 h, daytime and night-time blood pressure values between hypertensive patients with and without left ventricular hypertrophy. Low- and high-frequency powers were higher in controls than in hypertensives; in particular, low-frequency power showed a progressive decrease through control subjects and hypertensives without and with left ventricular hypertrophy. Furthermore, significant negative correlations were found between left ventricular mass index and low- and high-frequency power. No difference was detectable in ultra-low- and very low-frequency power. During daytime low- and high-frequency power were higher in controls than in hypertensives; during night-time, low- and high-frequency power increased significantly in all groups and low-frequency power was still higher in control subjects. CONCLUSIONS: Considering that, when analysed over 24 h Holter recording, low- and high-frequency power both reflected the parasympathetic modulation of heart rate, the present results demonstrate a parasympathetic withdrawal in hypertension; this sympathovagal imbalance is greater in patients with cardiac hypertrophy and is related to the increase in left ventricular mass.

Adult↗
PubMed1995

Assessment of cardiac autonomic control by heart period variability in patients with early-onset familial obesity.

For quantitative assessment of cardiac autonomic control, time and frequency domain measures of heart period variability were calculated by 24 h Holter recording in 10 young obese women with early-onset familial obesity and in 10 control subjects. Ultra low frequency and very low frequency power were lower in obese subjects than in controls (P < 0.05). High frequency power, a pure measure of vagal tone, was comparable between the two groups. However, low frequency power, which analysed over a 24 h Holter recording reflects parasympathetic more than sympathetic activity, was slightly lower in obese subjects than in controls (P = 0.06). Body mass index showed an inverse correlation with total power (r = -0.62; P < 0.05) and separately with ultra low (r = -0.59; P < 0.01), very low (r = -0.64; P < 0.005), low (r = -0.61; P < 0.005) and high frequency power (r = -0.53; P < 0.05). These results demonstrate a parasympathetic withdrawal increasing body weight. The reduction of ultra low frequency and very low frequency power, which are associated with sudden death, may help to explain the higher cardiovascular risk in obesity.

Adolescent↗
PubMed1995

Interruption of the ferredoxin (flavodoxin) NADP+ oxidoreductase gene of Escherichia coli does not affect anaerobic growth but increases sensitivity to paraquat.

Ferredoxin (flavodoxin) NADP+ oxidoreductase participates in methionine biosynthesis and in the function of two anaerobic enzymes, pyruvate formate-lyase and ribonucleotide reductase. We prepared insertion mutants of Escherichia coli lacking a functional enzyme. They do not require methionine and they grow well anaerobically, but they show increased sensitivity to paraquat.

Acetyltransferases↗
PubMed1995

Herpes simplex virus type 1 DNA replication is specifically required for high-frequency homologous recombination between repeated sequences.

Using an assay for recombination that measures deletion of a beta-galactosidase gene positioned between two directly repeated 350-bp sequences in plasmids transiently maintained in COS cells, we have found that replication from a simian virus 40 origin produces a high frequency of nonhomologous recombination. In contrast, plasmids replicating from a herpesvirus origin (oris) in COS cells superinfected with herpes simplex virus type 1 (HSV-1) show high levels of homologous recombination between the repeats and an enhanced recombinogenicity of the HSV-1 a sequence that is not seen during simian virus 40 replication. When the same assay was used to study recombination between 120- to 150-bp repeats in uninfected Vero cells, the level of recombination was extremely low or undetectable (< 0.03%), consistent with the fact that these repeats are smaller than the minimal efficient processing sequence for homologous recombination in mammalian cells. Recombination between these short repeats was easily measurable (0.5 to 0.8%) following HSV-1 infection, suggesting that there is an alteration of the recombination machinery. The frequency of recombination between repeats of the Uc-DR1 region, previously identified as the only segment of the HSV-1 a sequence indispensable for enhanced a-sequence recombination, was not significantly higher than that measured for other short sequences.

Animals↗
PubMed1995

Alterations in lymphocyte subsets as prognosticators of postoperative infections.

OBJECTIVE: To evaluate changes in lymphocyte subsets after major abdominal and thoracic operations, and to correlate changes with the development of clinically relevant infections postoperatively. DESIGN: Open study. SETTING: University hospital, Italy. SUBJECTS: 33 patients who were to undergo major abdominal or thoracic operations. INTERVENTIONS: Lymphocyte subsets were measured by cytofluorimetry before operation and 1, 3, 5, and 7 days postoperatively. MAIN OUTCOME MEASURES: Correlation between changes in the number of lymphocyte subsets and development of infection. RESULTS: Lymphocyte subsets were within the reference range in all patients before operation. 10/33 Patients developed infections (pneumonia, bacteraemia, or wound or urinary tract infections) between the second and the ninth days postoperatively (30%). On day 1 the numbers of all lymphocyte subsets had decreased significantly compared with the preoperative measurements in all patients (CD3 p < 0.01, CD4 p < 0.001, and CD8 p < 0.05). The reduction in CD3 was significantly greater in the group that developed infections (p < 0.001). Among patients who did not develop infections the numbers of lymphocyte subsets had returned to the reference range within a week of operation whereas among patients who developed infections they remained depressed (p < 0.05). CONCLUSION: The synchronous reduction in numbers of all lymphocyte subsets on the first day postoperatively to below 50% of the reference range (CD3 to < 600/microliters, CD4 to < 400/microliters, and CD8 to < 250/microliters) predicted the development of infection postoperatively with an accuracy of 89%, a sensitivity of 80%, and a specificity of 96%.

Adult↗
PubMed1995

[Hematological serological valves, and organ weight in adult Sprague-Dawley rats].

Sprague-Dawley rats are frequently used in experiments and their normal hematological, serologic and anatomical parameters are not easily available. The aim of this study was to measure these parameters in adult Sprague-Dawley rats. Twenty-four rats (12 males) whose weight ranged between 200 and 300 g, raised at the Instituto de Salud Pública in controlled environmental conditions and fed with pellets were studied. After a 24 h fast, animals were anesthetized with Droperidol and Ketamine, and after obtaining a cardiac blood sample, sacrificed by exsanguination. Most organs were withdrawn and weighed. Mean values for blood glucose, calcium, amylase, total proteins, cholesterol, AST, ALT, bilirubin, alkaline phosphatases, electrolytes and complete blood count were determined. Heart, lung, pancreas, kidney and testicle mean weight was also calculated. Male and female rats had significant differences in packed red cell volume, white blood cell count and hemoglobin.

Animals↗
PubMed1994

Inhibition of ribonucleotide reductase by 2'-substituted deoxycytidine analogs: possible application in AIDS treatment.

After phosphorylation to the corresponding diphosphates, 2'-azido-2'-deoxycytidine and 2'-difluorocytidine act as powerful inhibitors of ribonucleotide reductase. Phosphorylation requires deoxycytidine kinase, an enzyme with particularly high activity in lymphoid cells. Therefore, the deoxycytidine analogs can be expected to inhibit the reductase with some specificity for the lymphoid system. Pretreatment of human CEM lymphoblasts with the analogs considerably increased the phosphorylation of 3'-deoxy-3'-azidothymidine (AzT). The increased phosphorylation of AzT is caused by a prolongation of the S phase of the cell cycle. Our results suggest the possibility of a combination of 2'-substituted deoxycytidine analogs with AzT in the treatment of AIDS. Gao et al. [Gao, W.-Y., Cara, A., Gallo, R. C. & Lori, F. (1993) Proc. Natl. Acad. Sci. USA 90, 8925-8928] have suggested the use of the ribonucleotide reductase inhibitor hydroxyurea for this purpose, since the resulting decrease in the size of deoxyribonucleotide pools decreases the processivity of the HIV reverse transcriptase. From our results it would appear that the 2'-substituted deoxycytidine analogs might be preferable to hydroxyurea.

Acquired Immunodeficiency Syndrome↗