Biomedical subjects

A Santucci

Publications and source records attributed to A Santucci.

At least 127 records · Page 7Linked to original sources

PubMed1992

Botulinum neurotoxins are zinc proteins.

The available amino acid sequences of 150-kDa botulinum and tetanus neurotoxins show the presence of a closely homologous segment in the middle of the light chain (NH2-terminal 50 kDa), which is the intracellularly active portion of the toxin. This segment contains the zinc binding motif of metalloendopeptidases, HEXXH. Atomic adsorption analysis of botulinum neurotoxins (serotypes A, B, and E) made on the basis of this observation demonstrated the presence of one zinc atom/molecule of 150-kDa neurotoxin. Conditions were found for the removal of the zinc ion with chelating agents and for the restoration of the normal metal content. The conserved segment, which includes the zinc binding motif, was synthesized and shown to bind [65Zn]2+. Chemical modification experiments indicated that two histidines and no cysteines are involved in Zn2+ coordination in agreement with a probable catalytic role for the zinc ion. The present findings suggest the possibility that botulinum neurotoxins are zinc proteases.

Amino Acid Sequence↗

PubMed1992

Purification and characterization of an acetone-inducible cytochrome P-450 from hamster liver microsomes.

A form of cytochrome P-450 has been purified to electrophoretic homogeneity from the hepatic microsomes of Syrian golden hamsters treated with acetone. This P-450 form, designated ha P-450j, had an M(r) of approximately 55,000, bound dimethyl sulphoxide and exhibited a CO-reduced absorbance maximum at 451 nm. The absolute spectra of its oxidized form indicated that ha P-450j was predominantly in the low-spin state. In a reconstituted system, ha P-450j showed relatively low catalytic activities towards 7-ethoxycoumarin, 7-ethoxyresorufin, aminopyrine, ethylmorphine and benzphetamine, whereas it catalysed the oxidation of aniline, acetone and thiobenzamide with a high catalytic-centre activity. In addition, ha P-450j catalysed at a high rate the high-affinity component of dimethylnitrosamine N-demethylase; in contrast, only the low-affinity component of diethylnitrosamine N-de-ethylase was efficiently catalysed. The addition of cytochrome b5 to the reconstitution system decreased the Km value for dimethylnitrosamine N-demethylase by a factor of 5 and increased the Vmax. value, and slightly enhanced the other activities. Thiobenzamide and diethyldithiocarbamate were found to be the most effective inhibitors of the ha-P-450j-dependent aniline hydroxylation. Polyclonal antibodies against rat P-450j recognized ha P-450j in immunoblots of control and treated hamster liver microsomes. Treatment of hamsters with acetone increased the apparent abundance of ha P-450j in microsomes, whereas phenobarbital and beta-naphthoflavone did not induce it. Analysis of N-terminal amino acid sequences demonstrated that ha P-450j has a high degree of sequence identity with rat P-450j. All the evidence presented in this study indicates that ha P-450j could represent the hamster orthologue of the previously described CYP2E1(s) of other species.

Acetone↗

PubMed1992

Molluscan sperm proteins: Ensis minor.

The three major proteins, EM1, EM5 and EM6, from the mature sperm of the bivalve mollusc Ensis minor have been partially sequenced in order to establish which category they belong to and their potential for phosphorylation. Protein EM1 is protamine-like with about 50% basic amino acids, some of which are included in SK(R) repeats. Three SPXX potential phosphorylation sites were observed in the N-terminal domain. EM1 does not fold (Giancotti et al. (1983) Eur. J. Biochem. 136, 509-516). Protein EM6 (approx. 270 residues) is histone H1-like, having a globular domain homologous to other H1 family proteins. The N-domain of EM6 contains SK(R) repeats like EM1, but there are few, if any, SPXX sites in the chain. Proteins EM1 and EM6 are the two proteins specific for mature sperm. Protein EM5, of about 150 residues and present at lower levels than EM1 and EM6, is also an H1-family molecule. A sequence from its globular domain shows close homology to chicken H5 and to sea urchin somatic H1. Its presence may relate to the existence of a low level of nucleosomal structure.

Amino Acid Sequence↗

PubMed1992

A simple clinical approach to discriminate between "true" and "pseudo" secondary failure to oral hypoglycaemic agents.

To discriminate between true secondary failure (TF) and pseudo-secondary failure (PF) to oral hypoglycaemic agents, we studied 34 non-obese non-insulin-dependent diabetic patients who were being treated with these drugs. Nine were in good control (GC) with oral treatment, while 25 showed apparent SF. During a controlled hospital diet, fasting blood glucose remained persistently high in 15 of these patients (TF), while in the other 10 patients it clearly improved (PF). Fasting plasma glucose (FPG) and HbA1c were higher and body mass index (BMI) was lower in TF patients than in PF patients (P less than 0.01). C-peptide concentrations differed significantly among the three groups both in the fasting state (TF 0.25 +/- 0.02 nmol/l, PF 0.70 +/- 0.03 nmol/l, GC 0.74 +/- 0.03 nmol/l; P less than 0.0001) and 6 min after glucagon injection (TF 0.50 +/- 0.04 nmol/l, PF 1.02 +/- 0.06 nmol/l, GC 1.14 +/- 0.07 nmol/l; P less than 0.0001). C-peptide and plasma insulin curves obtained after a standard mixed meal also showed significant differences (P less than 0.001). In particular, there was a statistically significant difference between GC and PF versus TF (P less than 0.05), while there was no statistical difference between PF and GC. We conclude that some patients with apparent SF can improve their metabolic control if they strictly adhere to a correct diet (PF); a single measurement of basal C-peptide concentration or examination of the C-peptide and insulin responses to a meal are useful indicators for distinguishing patients with PF from those with TF to oral hypoglycaemic agents.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed1992

Ambulatory blood pressure recording in diabetic patients with abnormal responses to cardiovascular autonomic function tests.

The aim of our study was to analyse the 24-h periodic pattern of blood pressure (BP) in diabetic patients with abnormal responses to cardiovascular reflexes, in order to evaluate the extent of the initial autonomic damage. We studied 44 patients with diabetes mellitus (14 insulin-dependent, 30 non-insulin-dependent; mean duration of disease 6.5 +/- 1.8 years) in good metabolic control (fasting glycaemia less than 140 mg/dl, postprandial glycaemia less than 180 mg/dl, fructosamine less than 285 mg/dl), divided into two subgroups, containing 21 normotensives (13 males and 8 females aged 28-72 years) and 23 hypertensives (13 males and 10 females aged 32-70 years) respectively. All patients showed abnormal responses to at least two out of four tests: deep breathing, lying to standing, Valsalva manoeuvre and postural hypotension. Two sex- and age-matched control groups were recruited, comprising 20 normotensive and 20 hypertensive diabetic patients without dysautonomia, respectively. The reference group consisted of 248 normotensives (135 males and 113 females, aged 18-76 years) and 212 mild-moderate hypertensives (130 males and 82 females, aged 27-66 years). Each patient underwent ambulatory BP monitoring for at least 24 h, using an auscultatory automatic device. Data concerning biological rhythms were analysed by means of periodic functions. We limited the Fourier partial sums to the first three harmonics.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Enhanced release of atrial natriuretic factor during exercise-induced myocardial ischaemia in patients after acute myocardial infarction.

To determine whether acute myocardial ischaemia induced by dynamic exercise can lead to changes in plasma levels of atrial natriuretic factor, we performed symptom-limited bicycle electrocardiographic tests in 20 males with recent acute myocardial infarction and in 8 control males. Ten patients developed exercise-induced myocardial ischaemia and 10 patients did not. There were no significant differences between the two groups with regard to age, site of myocardial infarction, urinary sodium, atrial sizes, radionuclide left ventricular ejection fraction, workload, baseline and peak-exercise heart rate, baseline and peak-exercise rate-pressure product, duration of exercise. Also baseline atrial natriuretic factor concentrations were similar in both groups (ischaemic patients: 34.51 +/- 15.73 pg/ml; nonischaemic patients: 27.17 +/- 8.74 pg/ml, NS), while peak-exercise atrial natriuretic factor concentrations were higher in patients with exercise-induced myocardial ischaemia (112.31 +/- 35.5 pg/ml) than in the others (80.46 +/- 23.43 pg/ml) (P less than 0.05). After 15 minutes of recovery, plasma atrial natriuretic factor levels were still raised only in the ischaemic patients (63.3 +/- 15.44 pg/ml, P less than 0.01), returning to baseline after 30 minutes in both groups. In control subjects, the behaviour of atrial natriuretic factor resembled that of the patients without exercise-induced ischaemia, with a significant increase at peak-exercise (from baseline levels of 23.1 +/- 10.5 pg/ml to peak-exercise levels of 91.3 +/- 14.5 pg/ml, P less than 0.0005) and a rapid return to baseline levels after 15 minutes of recovery (28.5 +/- 10.6 pg/ml, NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Serum autoantibodies against glial fibrillary acidic protein in brain aging and senile dementias.

Autoantibodies against glial fibrillary acidic protein (GFAP) were investigated by ELISA test in sera of patients suffering from senile dementias and in healthy aging people. One hundred eight subjects divided into control, vascular dementia (VD), presenile Alzheimer's disease (AD), and senile Alzheimer's disease (SDAT) groups were included in the study. VD patients showed the highest antibody titers when compared to controls, whereas AD had the lowest titers when compared to the other groups. These results do not support the utility of anti-GFAP antibodies as useful markers of Alzheimer's disease, suggesting that their presence is a secondary phenomenon to blood-brain barrier disruption.

Aged↗

PubMed1992

Natriuretic hormones in young hypertensives and in young normotensives with or without a family history of hypertension.

The behavior of plasma atrial natriuretic factor (ANF) and digoxin-like substance (DLS), and the daily urinary excretion of kallikrein (uKK) were evaluated in young hypertensives and in young normotensives with or without a family history of essential hypertension. Each group was also evaluated, separating those with low plasma renin activity from the total sample. The sample group was made up of 75 young males; 31 hypertensives (mean age 22.7 +/- 2.5 years), 28 normotensives with hypertensive heredity (normotensives F+) (mean age 22.2 +/- 1.9 years) and 16 normotensives (mean age 22.0 +/- 2.1 years). An inverse correlation between ANF and PRA was shown in all groups. In hypertensives, ANF was inversely correlated with uKK (r = -0.664, P less than .0001). Plasma ANF (P less than .012) and DLS (P less than .0001) were higher in hypertensives than in normotensives, while uKK excretion was lower (P less than .0001). Plasma levels of DLS were higher in F+ normotensives than in normotensives (P less than .003). Low renin hypertensives showed the lowest uKK excretion (P less than .0001 v normal-high renin hypertensives). Furthermore, low renin hypertensives showed the highest plasma levels of ANF (P less than .0001 v normal high renin hypertensives) and DLS (P less than .012 v normal-high renin hypertensives). Plasma ANF (P less than .0001) was higher, while uKK was lower (P less than .045) in low renin F+ normotensives than in normal-high renin ones. In conclusion, our data indicate that plasma ANF and DLS are elevated since the early phase of hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Effects of high altitude exposure on plasma and urinary digoxin-like immunoreactive substance.

Six young healthy subjects underwent a 20 day exposure to altitude, at 4930 m (16,174 ft), to evaluate possible plasma and urine digoxin-like immunoreactive substance (DLIS) changes accompanying the altered water and electrolyte balance induced by hypoxia. We studied DLIS, plasma renin activity (PRA), aldosterone, atrial natriuretic peptide (ANP), and arginine vasopressin (ADH) in serial blood and urine samples. An increase in DLIS in plasma (P less than .005) and urine (P less than .01) was found, while aldosterone was decreased (P less than .02). PRA, ADH, and ANP did not change significantly. A trend to a greater loss of sodium through urinary excretion, correlated with urinary DLIS values (r = 0.47, P less than .01), was observed. Data suggest a possible important role of DLIS in adaptive response of human organism to high altitude.

Adult↗

PubMed1992

[Cardiac and renal sodium-modulating hormones in juvenile arterial hypertension. The physiopathological aspects and therapeutic results of a trial at the Policlinico Militare Celio in Rome].

Sodium balance plays a primary role in blood pressure regulation. Atrial natriuretic peptide, a recently discovered natriuretic substance, seems to participate in renal sodium handling, but its behavior in essential hypertension has not been fully defined. In our study, to avoid the "contamination" of factors other than hypertension, we evaluated the plasma levels of atrial natriuretic peptide in young men at military draft age. Our main results showed that plasma atrial natriuretic peptide levels are higher in young hypertensives with low plasma renin activity and low urinary excretion of active kallikrein. The influence of a positive genetic background for essential hypertension on plasma atrial natriuretic peptide levels was also investigated. Our data showed slightly elevated levels of the atrial hormone in young normotensives with a family history of hypertension.

Adult↗

PubMed1992

[Effects of acute and protracted hypoxia on plasma levels of atrial natriuretic factor].

Acute hypoxia stimulates the release of atrial natriuretic factor (ANF) from isolated rat and rabbit hearts. Increased ANF plasma levels have been found in rats exposed to chronic hypoxia and recently some studies have been conducted on men, with discordant results. The aim of the present study was to verify changes in ANF plasma levels during acute and prolonged hypoxia in young healthy men. We studied 22 subjects (aged 20-28 years, mean 22.7 years) during a simulated exposure to altitude (5000 m) in a hypobaric chamber for 3 hours (A), and 6 subjects (aged 24-51 years, mean 36.5 years) during the scientific expedition to mount Poumori (Nepal 4930 m altitude) with an exposure at maximum altitude for 20 days (B). ANF was measured by the radioimmunoassay method. Results (pg/ml): (A) baseline: 29.4 +/- 18.6; 120 min: 32.0 +/- 17.4 (NS); 180 min: 35.4 +/- 17.1 (p less than 0.05). (B) baseline: 39.6 +/- 13.3; third day: 38.2 +/- 14.1; fifth day: 31.3 +/- 11; seventh day: 29.1 +/- 13.5; tenth day: 32.2 +/- 20.8; fifteenth day: 37.9 +/- 20.2; twentieth day: 34.6 +/- 23.7 (all differences were not significant). In (B) we observed a higher dispersion of values perhaps due to individual variability. The different behaviour of ANF plasma levels in acute and chronic conditions might be due to the adaptive modification of different physiological parameters as loss of plasma volume, natriuresis and attenuation of tissue hypoxia by enhanced erythropoiesis, observed more evidently during prolonged exposure.

Acute Disease↗

PubMed1992

Insulin resistance and essential hypertension: pathophysiologic and therapeutic implications.

PURPOSE: Essential hypertension is often accompanied by metabolic abnormalities, which commonly include insulin resistance. In this paper we review data on the effects of different antihypertensive drugs on insulin resistance. DATA ANALYSIS: A number of reports have described a frequent association between hyperinsulinemia, hypertension and obesity. In epidemiological surveys, increased insulin concentrations have been seen in hypertensives and have been correlated with cardiovascular risk. Although the impact of antihypertensive therapy on glucose and lipid metabolism has been widely studied, few researchers have investigated the effects of different antihypertensive drugs on insulin resistance. An analysis of available data from controlled studies has shown that the use of thiazides is correlated with a decrease in insulin sensitivity. Pollare and co-workers tested insulin sensitivity by using the glucose-clamp technique in hypertensive patients, and found a 21% decrease in insulin sensitivity during atenolol treatment. Similar findings have been described with metoprolol. In contrast, calcium antagonists do not alter insulin resistance and/or sensitivity. At present, angiotensin converting enzyme (ACE) inhibitors seem to be the only drugs able to improve insulin sensitivity. CONCLUSIONS: ACE inhibitors may improve insulin-dependent glucose uptake, thus leading to a reduction in insulin concentrations. Calcium antagonists appear to preserve insulin sensitivity. Since insulin resistance may be an additional risk factor for cerebral and vascular disease, these drugs may be particularly useful in insulin-resistant hypertensives.

Antihypertensive Agents↗

PubMed1992

[Behavior of the lithium excretion fraction in hypertensive patients during variations of sodium intake].

Fractional excretion of lithium (FeLi) is a marker of proximal tubular sodium reabsorption. During different sodium intakes (normal = 120 mEq/day, low = 40 mEq/day and high = 240 mEq/day) fractional lithium excretion was evaluated in essential hypertensive patients (n. 19) and control subjects (n. 5). Our data showed that FeLi was higher in hypertensives than in controls. Dividing hypertensives on the basis of blood-pressure sensitivity, salt resistant patients showed lower FeLi levels as compared to salt sensitive ones. Our findings indicate that proximal tubular sodium reabsorption is decreased in essential hypertension; this behavior is particularly evident in salt sensitive patients, suggesting that factors affecting proximal tubular function are activated in these patients in order to reduce the impairment of renal excretory capability.

Adult↗

PubMed1991

Iron carrier proteins facilitate engraftment of allogeneic bone marrow and enduring hemopoietic chimerism in the lethally irradiated host.

Cell-free supernatants of rabbit bone marrow were fractionated, separated, and purified by Ultrogel and Superose chromatography. A single fraction promoted engraftment of allogeneic bone marrow and enduring hemopoietic chimerism across the H-2 barrier in lethally irradiated mice. This "bio-active" fraction, analyzed by reducing SDS-PAGE electrophoresis, and transblotted on PVDF membrane, and purified by reverse-phase HPLC and SDS-PAGE electrophoresis yielded a main prealbumin band that when examined for primary structure by Edman degradation, proved to be rabbit transferrin. This was also attested by highly specific precipitation of the prealbumin band with polyclonal antibodies to rabbit transferrin. Iron-saturated human transferrin, lactotransferrin, and egg transferrin (conalbumin) were assayed in irradiated C57BL/6 mice infused with bone marrow from histoincompatible BALB/c donors. Mice treated with iron-loaded transferrins survive and develop enduring allogeneic chimerism with no discernible signs of graft-versus-host disease. Iron carrier proteins thus provide an unique means of achieving successful engraftment of allogeneic bone marrow in immunologically hostile murine H-2 combinations.

Amino Acid Sequence↗

PubMed1991

In vitro chemosensitivity of newly diagnosed and relapsing acute non-lymphoid leukemia patients.

We evaluated the in vitro sensitivity of circulating blasts from 25 newly diagnosed and 7 relapsing ANLL patients to drugs employed in vivo for inducing remission. Ten of the 14 newly diagnosed complete responders were in vitro sensitive to cytosine arabinoside and daunorubicin, whereas 10/11 non-responders were resistant to both agents. Although cells from all 7 relapsing patients were in vitro sensitive to the remission inducing agents, only 4 entered complete remission. Even if only indicative, these findings suggest that the poor prognosis of relapsing patients may be due, at least in part, to factors other than drug resistance. Moreover, the chemosensitivity test adopted is a better predictor in newly diagnosed than relapsing patients, as indicated by the concordance between in vitro and in vivo results.

Adult↗

PubMed1991

Tyrosine 65 is photolabeled by 8-azidoadenine and 8-azidoadenosine at the NAD binding site of diphtheria toxin.

8-Azidoadenine and 8-azidoadenosine, two photoactivatable derivatives of adenine and adenosine, are competitive inhibitors of diphtheria toxin of similar potency with respect to their parent compounds. On irradiation, the two tritium-labeled photoactivatable azidoadenines bind covalently and specifically to an enzymic fragment of diphtheria toxin that is known to bind to NAD. This photolabeling is protected by the enzyme substrate NAD. The radiolabeled protein was fragmented, and the radioactive fragments were sequenced. Tyr-65 is labeled specifically by both photoreagents, and its labeling was reduced strongly when NAD was present during irradiation. Labeling is also reduced strongly by adenine, adenosine, and nicotinamide. These results suggest that Tyr-65 is at the NAD binding site of diphtheria toxin and that the competitive inhibitors adenine, adenosine, and nicotinamide bind to the same portion of the catalytic center of the toxin.

Adenine↗

PubMed1991

An antigenic determinant common to human chorionic somatomammotropin and human growth hormone revealed by limited proteolysis of immune complexes.

An epitope of human chorionic somatomammotropin for one of the monoclonal antibodies raised against the whole antigen has been identified. We compared the release of peptides from limited proteolysis of the antigen in the presence and absence of the related antibody. Using enzymes of different specificity, we could determine the amino acid sequence that can be considered at least inclusive of the epitope. The monoclonal antibody selected is 100% cross-reactive with human growth hormone, so the antigenic determinant identified is shared by the two protein hormones.

Amino Acid Sequence↗

PubMed1991

Noise stimulus in normal subjects: time-dependent blood pressure pattern assessment.

Environmental noise may have various effects on blood pressure. The aim of our study was to verify noise impact on blood pressure in normal young subjects, using the "white noise" stimulus. Thirty subjects (16 males and 14 females, median age 22 years) were studied. The presence of hypertension, hypertensive hereditibility and loss of acoustic acuity were criteria for exclusion. Noninvasive measurements of systolic and diastolic blood pressure at three-minute intervals were performed with an oscillometric system (Omega 1000, In Vivo Research), for each of four phases of the trial. After an initial rest phase (9 min) to avoid the patient's "alarm reaction," "white noise" with an intensity equal to 40, 100, and 40 adjusted decibels (dBa) was administered consecutively for 18 min (2nd phase), 9 min (3rd phase), and 18 min (4th phase), respectively. Preliminary analysis with standard statistical tools was not able to analyze the blood pressure patterns during the test. On the contrary, polygonal analysis, taking into account the "time-dependent" changes, showed that noise exposure (100 dBa) significantly increased systolic blood pressure in 22/30 subjects. However, systolic blood pressure rose only at the beginning of the 100 dBa exposure, indicating that stimulus changes rather than noise are key provoking factors in blood pressure increases.

Adult↗