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Biomedical subjects

A Bossi

Publications and source records attributed to A Bossi.

At least 91 records · Page 5Linked to original sources
PubMed1976

Effect of phenobarbital on cyclophosphamide metabolism in rats.

1. The pharmacokinetics of cyclophosphamide and its alkylating metabolites have been studied in rats whose liver microsomal enzymes had been induced by phenobarbital pre-treatment. 2. Serum levels of cyclophosphamide were determined using a new g.l.c. method. The half-life of cyclophosphamide in blood of rats pre-treated with phenobarbital was shorter than in control rats. This change is closely related to higher rates of production of p-nitrobenzylpyridine-positive alkylating metabolites of cyclophosphamide, which in turn is followed by their more rapid disappearance from the circulation. 3. Urinary excretion reflects this situation; lower amounts of cyclophosphamide and higher concentrations of its alkylating metabolites are present in the urine of phenobarbital-treated rats. 4. Perfusion of livers isolated from phenobarbital-pre-treated rats confirmed the results in vivo. With this preparation, too, disappearance of cyclophosphamide was more rapid and formation of its alkylating metabolites was accelerated after phenobarbital treatment.

Alkylating Agents↗
PubMedDate not supplied

Is gravity on our way? The case of polyacrylamide gel polymerization.

Potential gravity-induced deformations of polyacrylamide matrices during gelling were investigated in two different initiator systems based on (i) photopolymerization with 100 microM methylene blue, 1 mM sodium toluene sulfinate (reducer) and 50 microM diphenyliodonium chloride (oxidizer) (photopolymerization) and (ii) chemical polymerization, utilizing the standard persulfate N,N,N',N'-tetramethylethylenediamine. In both systems, it is seen that convective flows are imprinted in the final gel structure above a critical gelling layer thickness, set at ca. 3 mm. In both systems, progressive increments of the solution density, from normodense (density = 1.0) up to isodense with the growing polymer chains (density = 1.3) do not inhibit the appearance of strong convective flows. However, gel inhomogeneities are completely abolished even in 10 mm gelling layers if polymerization is performed in presence of density gradients, notably of sucrose, from 0 to 20%, 0 to 40% and 0 to 60%. Even the shallower gradient (0-20% sucrose) is able to completely abolish convective flows in persulfate-driven polymerization. It is hypothesized that such disturbances are not created by sedimentation of the growing polymer chains in the gravitational field, but are produced by the reaction exothermality, which produces strong buoyancy-driven flows. It is additionally demonstrated that persulfate polymerization is sensitive to oxygen absorbed from the top liquid layers, which should be carefully protected by an overlay of organic solvent. Methylene blue-induced polymerization appears to offer a series of unique advantages over chemical initiation with persulfate.

Acrylic Resins↗
PubMedDate not supplied

Immobilized pH gradients: new pK values of acrylamido buffers in poly(N-acryloylaminoethoxyethanol) matrices.

A novel matrix consisting of N-acryloylaminoethoxyethanol, a hydrophilic monomer extremely resistant to hydrolysis, was recently reported by Chiari et al. (Electrophoresis, 1994, 15, 177-186). When using it as a matrix for grafting immobilized pH gradients for isoelectric focusing, a shift in protein spot position was noticed. This was attributed to a shift in pK values of the Immobiline buffers when changing from the standard poly(acrylamide) to a poly(N-acryloylaminoethoxyethanol) matrix. A series of 1 pH unit gradients was constructed, where a single buffering Immobiline was used and titrated with a counterion having a pK removed by at least 3 pH units from the nearest extreme of the generated pH interval. It was noted that all compounds became weaker acids and bases, with a delta pK ranging from -0.02 to -0.06 for the acids (pK 3.6, 4.4, and 4.6) and a delta pK ranging from -0.12 tp -0.20 for the bases. The new pK values for the seven commercially available buffers are thus pK 3.6-->pK 3.58, pK 4.4-->pK 4.36, pK 4.51-->4.45, pK 6.21-->6.09, pK 7.06-->6.94, pK 8.50-->pK 8.37, and pK 9.59-->pK 9.39. These values refer to 10 degrees C in the gel phase, the first value in poly(acrylamide) and the second in poly(N-acryloylaminoethoxyethanol).

Acrylamides↗
PubMedDate not supplied

Linear models for the analysis of variability in factorial designs: an application to anthropometric indicators.

This paper has two aims. One is to evaluate, in a set of 9740 'reference' neonates born in five Italian centres (Trieste, Milan, Parma, Rome, Bari) during 1973-1976 the effects of gestational age and birthplace on the variability of crown-heel length and head circumference at birth; this is a preliminary step in the construction of 'Italian' intrauterine growth standards for such anthropometric measures. The other aim is to put the various techniques for the analysis of variability into a common framework of Linear Models, either Generalized or Classical, to compare their main features and provide some indications about their application.

Analysis of Variance↗
PubMedDate not supplied

Ano-rectal manometry as an evaluating test for impaired ano-rectal function in diabetes mellitus.

Diarrhea and/or rectal incontinence may represent a sign of autonomic neuropathy in diabetes. The present investigation was performed to study ano-rectal function and reactivity to appropriate stimuli in 20 diabetic patients with or without autonomic neuropathy (14 insulin-dependent diabetics; 6 non-insulin-dependent diabetics; mean age 39.2 years; mean duration of diabetes 12.6). Twenty-five healthy subjects (mean age 43.5 years) were studied as controls. All subjects underwent ano-rectal manometry by means of special open-ended-tip catheters connected with a 6-channel polygraph. A rectal latex balloon was inflated with 30 or 60 ml air to induce a stimulus which, under normal conditions, is apt to relax the internal sphincter and to contract the external one (ano-rectal inhibitory reflex). Eleven diabetics had symptoms and signs of autonomic neuropathy: 8 of these (73%) showed marked abnormalities of ano-rectal function (i.e. no response even to maximum stimulus or contraction of both sphincters). All non-neuropathic patients showed a normal pattern of ano-rectal manometry. A relationship between abnormal response to rectal stimulation and the presence of autonomic neuropathy involving the pelvic parasympathetic section or regional intramural plexuses may be suspected and demonstrated in diabetic neuropathic patients.

Adult↗
PubMedDate not supplied

Clinical and instrumental diagnosis of autonomic neuropathy in insulin-dependent diabetes.

The author report a study of the relationship between symptomatic autonomic neuropathy and the response to simple cardiovascular autonomic tests (Valsalva maneuver, handgrip-test, detection of postural hypotension), in a large series of insulin-dependent diabetics (IDD). Symptoms of autonomic neuropathy were referred by 28 out of 130 IDD, prevalence and severity showed a clear relationship with the duration of diabetes. Only 4 out of 36 patients examined showed a pathologic response to the handgrip-test, while an abnormal Valsalva maneuver was evident in 24 out of 113 IDD. The data show that while the recognition of symptoms indicating a widespread autonomic derangement is rather easy, the diagnosis of autonomic neuropathy may be more difficult in the presence of mild or unspecific symptoms. The Valsalva maneuver exhibited the higher frequency of abnormal responses suggesting that the parasympathetic cardiovascular regulation may be impaired earlier than the sympathetic one. This early subclinical autonomic neuropathy may be due to metabolic or functional factors. Even if clinical consequences of an autonomic derangement of cardiovascular regulation may be serious, in our opinion subclinical impairment, being detectable in a large proportion of patients within the first year of disease, is unlikely to have a short-term severe prognostic value.

Adolescent↗
PubMedDate not supplied

Hypoproteinemia in acromegaly.

Although it is well known that growth hormone may influence protein metabolism, few investigations have been undertaken on serum protein levels in acromegaly; recently hypoglobulinemia has been observed in this endocrine disorder. In 28 acromegalic patients and 56 control subjects sera have been analyzed for total protein determination and for electrophoretic protein separation. The results have shown that in acromegalic there is a slight but statistically highly significant decrease of serum total protein (mean +/- SE 6.66 +/- 0.07 g/100 ml vs 7.10 +/- 0.07 g/100 ml), albumin, alpha 1 and alpha 2-globulins. Since growth hormone stimulates protein synthesis, the pathophysiological significance of hypoproteinemia of acromegaly is at present obscure.

Acromegaly↗
PubMedDate not supplied

Continuous enzymatic hydrolysis of beta-casein and isoelectric collection of some of the biologically active peptides in an electric field.

Among the milk proteins, bovine beta-casein has the peculiarity of containing in its sequence some peptides liable to interfere in mineral nutrition and some peptides with opioid (casomorphines), antihypertensive, and immunomodulatory activities. In this work we propose a novel type of multicompartment enzyme reactor, operating under an electric field, for the continuous hydrolysis of milk proteins such as beta-casein. The enzyme trypsin is trapped, with zwitterionic buffering ions and its substrate beta-casein, in solution between two isoelectric membranes having pI values encompassing the isoelectric point of the enzyme. Additionally, beta-casein is captured inside the same reaction chamber with the aid of sieving membranes, since its pI is too far away from the pI of trypsin. This setup permits the continuous operation at the pH of optimum of activity. The peptides, arising from tryptic hydrolysis of beta-casein, are removed under the influence of the electric field and collected in different chambers in which they are isoelectric and isoionic as well. The purity of the peptides collected is ascertained by capillary zone electrophoresis and their identity confirmed by N-terminal sequencing and MALDI-TOF mass spectrometry. This setup allows continuous harvesting of some biologically-active peptides in a pure form. The major advantages of such a reactor system over conventional batch reactors are the great increase in enzyme utilization efficiency and the overall reactor productivity.

Amino Acid Sequence↗
PubMedDate not supplied

Neonatal morbidity risk: a study of the relationship to birthweight and gestational age in four Italian centres.

Data collected in four Italian centres, in the framework of a multicentre survey of perinatal preventive medicine sponsored by the Italian National Research Council from 1973, have been used to evaluate the relationship among neonatal morbidity (NM), birthweight (BW) and gestational age (GA). A linear logistic model, whose structure is the same in all the centres, appeared to be appropriate to fit the observed NM relative frequencies corresponding to each cell of the two-way (BW X GA) layout. Fitted models have been used to represent NM risk as a function of GA and BW, providing a chart of neonatal morbidity risk for each centre. Although such charts show recognizable similarities (among the centres) confirming the coherence in the results attained, some differences of expected morbidity risks occur in the classes with higher GA and BW. The characteristics of the women attending, especially socio-economical level and incidence of high-risk pregnancies, which are specific for each perinatal centre, may account for some of the differences in NM risk for given GA and BW classes.

Birth Weight↗
PubMedDate not supplied

Italian standards for crown-heel length and head circumference at birth.

Cross-sectional standards for crown-heel length and head circumference at birth are presented, based on 16336 reference neonates born in six towns in North, Central and South Italy, between 1973 and 1981, and included in a multicentre survey of perinatal preventive medicine. Single liveborn infants, with no congenital anomalies, of mothers with no risk factor for pregnancy, such as diabetes, hypertension, vaginal bleeding, previous stillbirths or abortions, were considered as the reference group. These were treated as a sample drawn from one reference population, regardless of birthplace. Large differences in social and environmental conditions typical of the six towns appeared to exert negligible effects on the reference neonates' dimensions. Unlike intrauterine growth charts published previously in Italy, these standards apply to any Italian neonate born between 32 and 43 weeks of gestation. Cross-sectional standards derived from anthropometric measurements of infants having different gestational ages should be regarded mainly as a tool for assessing size and proportion of neonates, rather than as growth charts for monitoring fetal development. This latter task should be fulfilled by longitudinal growth charts: to date, intrauterine ultrasonography has not provided data sufficient to replace cross-sectional standards.

Biometry↗
PubMedDate not supplied

Effect of phenobarbital on cyclophosphamide cytotoxic activity and pharmacokinetics in mice.

The interaction between cyclophosphamide (CPA) and phenobarbital (PB) was investigated in B6D2F1 mice, checking both the antileukemic and immunosuppressive activity together with the serum levels of CPA and its metabolites. A reduced cytotoxic activity of CPA has been observed when PB is given for 2 days before CPA and an interval of at least 6 hours elapses between the last treatment of PB and the administration of CPA. On the contrary, when PB is given simultaneously with CPA for 2 or 4 consecutive days, an increased antileukemic activity of CPA occurs. In the experimental condition where PB decreases the activity of CPA, serum levels of CPA, assayed by means of a new specific gas-chromatographic method, and of its NBP-alkylating metabolites, indicate that this effect may be explained on a pure pharmacokinetic basis. However, for the situation where an increased effect of CPA was observed under the influence of PB, pharmacokinetic data did not provide a clear explanation.

Animals↗
PubMedDate not supplied

The role of radiotherapy in the treatment of carcinoma of the prostate: a survey of clinical practices in Lombardy, Italy, by the AIRO-Lombardia Cooperative Group. Italian Association for Radiation Oncology.

AIMS AND BACKGROUND: We report the results of a survey performed in 1994 by the AIRO-Lombardia Cooperative Group, on the clinical patterns of radiation treatment for prostatic carcinoma in Lombardy, Italy, involving all radiotherapy centers serving an overall local population of about 8,800,000 people. METHODS: A questionnaire was sent to all 13 radiotherapy centers throughout Lombardy, asking for demographic and treatment details concerning the local population of patients with a localized (T1-4, N0-1, M0) carcinoma of the prostate treated with radiotherapy; 12 centers responded, making the basis for the present report. RESULTS: Analysis of collected data showed that in Lombardy: a) approximately 400 patients per year are irradiated for a localized carcinoma of the prostate, accounting for less than 30% of the total expected number of patients with this disease presentation; b) a complete staging (with PSA, transrectal ultrasonography, abdomino-pelvic CT or MRI scan and total-body bone scan) is performed in over 95% of patients before initiating radiotherapy; c) significant differences exist between radiotherapy centers as regards treatment planning and delivery. CONCLUSIONS: An urgent need exists for implementing procedures aimed at standardizing radiotherapy procedures within Lombardy.

Carcinoma↗