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Biomedical subjects

F Valle

Publications and source records attributed to F Valle.

At least 55 records · Page 3Linked to original sources
PubMed1993

Sex hormones and sex hormone-binding globulin in males with chronic viral hepatitis during recombinant interferon-alpha 2b therapy.

The effect of long-term treatment with recombinant interferon-alpha 2b (IFN-alpha 2b) on luteinizing hormone (LH), testosterone, free testosterone, and sex hormone-binding globulin (SHBG) was evaluated in 7 male patients suffering from chronic viral hepatitis. The drug was given three times a week for 6 months in a single standard dose of 3 x 10(6) units. Hormone evaluations were performed in basal conditions and every 2 months for 12 months. Serum testosterone values decreased after IFN treatment, reaching the lowest levels at the 6th month. However, testosterone values did not fall below the normal range. Serum SHBG concentrations, which were above the normal range in basal conditions, also decreased after IFN. Serum-free testosterone and LH concentrations did not change during IFN therapy. IFN-alpha 2b at the dose and schedule employed was not responsible for any measurable imbalance in male sex hormones.

Adult↗
PubMed1993

Anti-hepatitis C virus antibodies and hepatitis C virus viraemia in haemodialysis patients.

Sera from 82 haemodialysis patients were tested for anti-HCV, HCV-RNA, and HBsAg. Alanine aminotransferase (ALT) activity was monitored weekly for 2 months. Anti-HCV was positive in 31 patients (37.8%), showing different single-peptide patterns. HCV-RNA was detected in 26 anti-HCV-positive patients (84%) and also in two of 21 anti-HCV-negative patients. Twenty-seven (87%) of the 31 anti-HCV-positive patients had persistently normal ALT values; 22 of these patients were HCV-RNA positive. The four patients with elevated ALT values had HCV viraemia. HBsAg was positive in nine anti-HCV-negative patients. The close correlation between HCV viraemia and HCV status, independently of ALT values, requires that anti-HCV dialysis patients must be considered potentially infective and dialysed with reserved machines and/or in separate shifts.

Adult↗
PubMed1993

Open access endoscopy: a large-scale analysis of its use in dyspeptic patients.

We examined 2,253 consecutive dyspeptic patients referred to our endoscopy service by general practitioners ("open" group) and hospital clinicians ("clinic" group) to study the prevalence of the various endoscopic findings according to patient age and the route of endoscopic referral. The results obtained are representative of that specific population. Normal endoscopic findings progressively lessened as patients' age increased, and the overall rate was as low as 26.5% in the open and 30.3% in the clinic groups. Erosive prepyloric changes and duodenitis were the most frequently noted abnormalities in patients < 40 years of age (16.9% and 20.1%, respectively, in the open and 11.6% and 14.2% in the clinic groups). Chronic gastritis was prevalent in patients > 60 years of age. Duodenal ulcer decreased from 9.7% (open) and 18% (clinic) in patients < 40 to 2% and 1.1% in patients > 60. No malignancy was found in patients < 40, while only approximately 1% of those < 60 had neoplasms. All our endoscopic findings, both in the open and the clinic groups, were not significantly different. No significant differences in symptoms were observed among patients with different endoscopic findings. We conclude that (a) endoscopy is really useful only in a small group of patients < 40 years of age; (b) individual symptoms alone have a poorly discriminant diagnostic power; and (c) restriction of open access endoscopy is not justified.

Adolescent↗
PubMed1993

[Vasovagal syncope].

The nature of most syncopal episodes, previously unknown, was recently elucidated by new diagnostic techniques such as the use of the tilt test. The vasovagal syncope can be clinically diagnosed by means of the tilt test. The transitory loss of consciousness during prolonged orthostasis is typically associated with sudden hypotension and bradycardia, which are commonly preceded by relative tachycardia and by premonitory symptoms such as pallor, nausea, asthenia, yawns, hyperventilation, mydriasis, humming, lasting several minutes. The nature of the vasovagal reflex is now better understood: in subjects with vasovagal syncope, during prolonged orthostasis, it was observed a fall in the venous return, inducing an increased sympathetic drive to the heart (with positive inotropic and chronotropic effect) and a lower ventricular filling. The powerful contraction around an almost empty cardiac chamber induces the activation of ventricular mechanoreceptors, and through a reflex mechanism, a sudden increase in the vagal and a sudden reduction in the sympathetic drive. These autonomic changes are responsible for a sudden hypotension and bradycardia. The discussion is still open about the origin of the reduced venous return: it probably originates from a redistribution in the blood volume, due to a venous pooling in the lower limbs or from a reduced muscle tone, because many subjects with vasovagal syncope are slender and with less developed muscle apparatus. Others suggest that a reduction in the sympathetic drive to the vessels, responsible for a progressive hypotension in the minutes preceding syncopal episodes, is the origin of the reduced venous return. In this review a diagnostic pattern for the assessment of the vasovagal syncope is suggested. The medical history, clinical examination, electro- and echocardiogram, chest x-ray identify two main groups of patients (with or without cardiopathy) who will follow different diagnostic protocols. The therapy of vasovagal syncope, which is based on beta-blockers, scopolamine, dysopiramide and plasma expanders, is reviewed.

Hemodynamics↗
PubMed1992

Carbon regulation and the role in nature of the Escherichia coli penicillin acylase (pac) gene.

Quantitative analysis of specific pac mRNA and a lacZ fusion to the 5'-terminal region of the pac gene demonstrated that both phenylacetic acid induction and catabolite repression by glucose are involved, at the transcriptional level, in the regulation of the pac gene. The studies presented here suggest that this regulation is also present in Escherichia coli transformed strains in which the pac gene was not originally present. Analysis of the nucleotide sequence of the 5'-terminal region of this gene, with a statistical algorithm, confirms that the putative promoter previously proposed by our group is the most feasible within this region. We demonstrate that penicillin acylase activity can confer on E. coli the ability to use penicillin G as a metabolic substrate, by detaching the phenylacetic group which can be used as a carbon source. Based on these data, the regulation properties of the pac gene studied in this work, and the specificity profile of the penicillin acylase enzyme we suggest a role for it in E. coli as a scavenger enzyme for phenylacetylated compounds.

Base Sequence↗
PubMed1992

gltF, a member of the gltBDF operon of Escherichia coli, is involved in nitrogen-regulated gene expression.

We report here the construction and analysis of insertional mutations in each of the three genes of the gltBDF operon and the nucleotide sequence of the region downstream from gltD. Two open reading frames were identified, the first of which corresponds to gltF. The gltB and gltD genes code for the large and small subunits, respectively, of the enzyme glutamate synthase (GOGAT). gltF codes for a protein, with a molecular mass of 26,350 Da, which is required for Ntr induction. Histidase synthesis was determined as a measure of Ntr function. First, insertions in gltB, gltD or gltF all prevent Ntr induction. Second, complementation analysis indicates that high-level expression of both the gltD and gltF genes is required for the induction of the Ntr enzymes under nitrogen-limiting conditions, indicating that the phenotype of the gltB insertion probably results from polarity on gltD and gltF. Third, glutamate-dependent repression of the glt operon appears to be mediated by the product of the gltF gene. Thus, the gltBDF operon of Escherichia coli is involved in induction of the so-called Ntr enzymes in response to nitrogen deprivation, as well as in glutamate biosynthesis.

Amino Acid Sequence↗
PubMed1991

The role of penicillin amidases in nature and in industry.

Penicillin amidase (PA) is the enzyme used commercially for the production of semisynthetic penicillins. During the past decade, a detailed picture of the structure and regulation of the gene encoding this enzyme has emerged, revealing a variety of interesting features that are unique among microorganisms. Clues to the biological role of this enzyme have been provided, as well as new strategies for the commercial production and utilization of PA.

Escherichia coli↗
PubMed1990

Intra-arterial blood pressure monitoring in the evaluation of the hypertensive athlete.

To compare the blood pressure (BP) changes during a long-distance run with those during bicycle ergometry, nine normotensive and 18 hypertensive joggers were studied by means of ambulatory intra-arterial monitoring. In all subjects the ergometric test caused a progressive increase in systolic and little change in diastolic BP. Exertional BP levels were closely related to pre-exercise baseline values (P less than 0.001). A different BP pattern was observed during track running, as a sharp rise in systolic BP reaching maximum values 2-4 min after the start was recorded. Subsequently, systolic BP progressively declined throughout the run, only to increase again during the final sprint. Diastolic BP fell markedly at the onset of the run and then remained substantially stable throughout. A poor relationship was observed between the BP values at peak exercise and baseline levels (P less than 0.05) as the normotensives showed a significantly higher BP response than the hypertensives. On the contrary, during the ergometric test a parallel increase in BP was recorded in the normotensive and the hypertensive joggers. No correlation was found between the BP response to track running and to bicycle ergometry. These results indicate that the BP response to a standard stress test is not predictive of the BP changes determined by a long-distance run. The BP increase with strenuous effort seems to be reduced in hypertensive individuals, probably because of latent impairment of cardiac performance.

Adolescent↗
PubMed1990

A single-blind pilot study comparing standard and half bedtime doses of ranitidine in the short-term healing of duodenal ulcer.

In this two-center, pilot trial we assessed the efficacy of single bedtime does of 150 mg ranitidine (half dose) and 300 mg ranitidine (full dose) in promoting duodenal ulcer healing by comparing the proportions of healed ulcers after 4 and 8 weeks of treatment. One hundred thirty-nine patients (106 men) were randomly allocated according to a prearranged treatment schedule to either dose and were treated single-blind (endoscopist). One hundred twenty-six patients (63 given 150 mg ranitidine and 63 given 300 mg) completed the trial. In the per-protocol analysis, 55 patients given full doses (81%) and 47 given half doses (70%) of ranitidine had healed ulcers at 4 weeks. Sixty full-dose and 55 half-dose patients (95% and 87%, respectively), had healed ulcers at 8 weeks. The difference was not significant using the chi 2 test (two-tailed), but the 95% confidence limits were in favor of the 300-mg dose. This study had a 75% power to detect a 25% difference in healing rates between the two groups.

Acute Disease↗
PubMed1989

Low bedtime doses of H2-receptor antagonists for acute treatment of duodenal ulcer.

Twenty-four-hour intragastric acidity was measured continuously over five separate occasions in 15 patients with healed duodenal ulcers. They were randomized to receive either placebo, cimetidine 800 mg, ranitidine 150 mg, famotidine 20 mg, or nizatidine 150 mg, given at 2200 hr in double-blind fashion. All H2-receptor blockers were more effective than placebo in suppressing both circadian (P less than 0.05-P less than 0.01) and nocturnal (P less than 0.002) gastric acidity, while there was no significant differences between the effects of the four active drugs in the same time periods. The percentage of nocturnal acid inhibition (2300-0800 hr) over placebo in terms of H+ values was virtually 100% with all active treatments. The effect on daytime (0800-1700 hr) and evening (1700-2300 hr) acidity of both placebo and the four H2-receptor antagonists was similar. Therefore, in the above doses H2-receptor blockers guarantee overnight anacidity to a similar degree and cause the physiological buffering of daily meals on gastric acidity to be fully exploited. Furthermore, the reducing effect of daily meals on drug action can be prevented. Since strong acid suppression strictly confined to the nocturnal period has been shown to be closely correlated with the highest ulcer healing rates, it is suggested that single low bedtime doses of H2-receptor antagonist should be evaluated in the acute treatment of duodenal ulcer.

Adult↗
PubMed1989

Beats modulate blood pressure during running.

Blood pressure (BP) changes during running were studied in 25 subjects with intraarterial monitoring. Periodic pulse pressure variations ranging from 20 to 200 mm Hg were recorded throughout the exercise. To prove that these pressure oscillations were due to a "beat" phenomenon 10 athletes ran with a Teruflex container filled with saline: pressure changes up to +/- 62 mm Hg were recorded in the container. These pressure waves were added by computer to the sphygmic waves recorded intraarterially in the same subject during bicycle ergometry: the resultant tracing showed a beat-shaped pattern similar to that recorded during running.

Adolescent↗
PubMed1989

Blood pressure changes during heavy-resistance exercise.

To study the mechanisms of the blood pressure changes during weight-lifting, three hypertensive and five normotensive body-builders underwent continuous intra-arterial monitoring. In two subjects (one normotensive and one hypertensive), intrathoracic and intra-abdominal pressures were also measured. Extremely high blood pressure elevations of up to 345/245 mmHg were observed during the lifts. Squatting caused the highest pressure rises and single-arm curls the lowest. Both the intrathoracic and the intra-abdominal pressures increased greatly during each lift and closely paralleled the changes in intra-arterial pressure. A close correlation was found between the blood pressure increase during the exercise and during a hand-grip test (r = 0.95, P less than 0.001). These results suggest that a pronounced increase in intra-thoracic and intra-abdominal pressures is a major determinant of the blood pressure elevations occurring during weight-lifting. The pressor reflex which accompanies static contractions and the individual baseline blood pressure levels also seem to affect the height of the pressure peaks.

Adult↗
PubMed1989

Gastric aspiration versus antimony and glass pH electrodes. A simultaneous comparative in vivo study.

To carry out a simultaneous comparison of the 24-h in vivo performance of antimony and glass electrodes and the findings of intermittent gastric aspiration, a triple-probe system with closely adjacent tips was positioned in the gastric corpus of 10 subjects representing different clinical and pharmacologic conditions. We showed that pH values measured with the antimony and the glass units were well correlated to those assessed in gastric aspirates (rs = 0.87; b = 1.079; a = -0.33; and rs = 0.85; b = 1.121; a = -0.38, respectively). A proportional correlation (rs = 0.86; b = 0.97; a = 0.02) was also found between the two intraluminal pH measurements. With regard to the error frequency distributions obtained by comparing the three measuring systems two at a time, the pH pairs differed by no more than 1 pH unit in most cases (greater than 90%). It can be concluded that antimony and glass pH electrodes can be used interchangeably in 24-h intragastric acidity studies in man.

Adolescent↗
PubMed1989

[Cold pressor test in the evaluation of autonomic neuropathy].

Neurogenic orthostatic hypotension is due to interruption of the baroreceptor reflex. To optimize the pharmacological therapy in this clinical setting the lesion should be carefully pinpointed and the degree of denervation established. To this purpose 7 patients with autonomic failure underwent ambulatory intraarterial monitoring, which showed the reversal of the normal 24-hour blood pressure (BP) pattern. During daytime BP gradually rose from its lowest point early in the morning to a peak during late evening. No BP fall was observed during sleep. Tilting test, Valsalva maneuver, hyperventilation, cold pressor test, handgrip and pharmacological tests showed interruption of the efferent pathway of the reflex. The BP fall 60 seconds after assuming the orthostatic position significantly correlated with the BP response to the cold pressor test (r = 0.89; p less than 0.01), while it did not with the BP changes during hand grip and hyperventilation and with the orthostatic increase of heart rate. Therefore, the BP response to the cold pressor test seems the most reliable indicator of the degree of autonomic dysfunction in the lesions of the efferent pathway of the reflex.

Aged↗
PubMed1988

Identification of a functional promoter for the Escherichia coli gdhA gene and its regulation.

Glutamate dehydrogenase (GDH) catalyzes the synthesis of L-glutamate from 2-oxoglutarate and ammonia. The complete nucleotide sequence of the Escherichia coli gdhA gene, as well as its 5' and 3' flanking regions have been previously reported [Valle et al., Gene 23 (1983) 199-209; 27 (1984) 193-199]. In this paper we present data on the GDH specific activities using both excess and limiting concentrations of ammonia as nitrogen sources. Evidence is presented on the regulation of the mRNA levels for this enzyme by the ammonia concentration in the growth medium. We have identified a single and apparently invariant transcript for several metabolic growth conditions. We also report the identification of a functional promoter and the corresponding transcription start point under several growth conditions. Finally, possible regulatory sequences located at the 5' flanking region of the gdhA gene are discussed.

Base Sequence↗
PubMed1988

Blood pressure changes during physical exercise (the beat phenomenon).

We have previously reported that blood pressure during running shows a peculiar pattern attributable to the beat phenomenon. To elucidate the mechanism behind this phenomenon in 10 amateur athletes, intra-arterial blood pressure was continuously recorded using the Oxford technique. During the run, each athlete carried on his chest a container filled with saline kept under pressure, connected to a second transducer. In the container, pressure waves ranging in amplitude from +/- 10 to +/- 62 mmHg were recorded. Their frequency was equal to that of the athletes' strides. When these waves were added by computer to the blood pressure tracing recorded during a bicycle ergometric test, the resultant harmonic proved to be similar to the tracing observed during running. The present results demonstrate that the running-induced blood pressure pattern is the sum of the accessory wave generated by the rhythmic aortic shocks produced by running locomotion and the normal sphygmic wave.

Adolescent↗