Biomedical subjects

M Rossi

Publications and source records attributed to M Rossi.

At least 19 recordsLinked to original sources

PubMed1995

Prevention of in vitro protein thermal aggregation by the Sulfolobus solfataricus chaperonin. Evidence for nonequivalent binding surfaces on the chaperonin molecule.

We have studied the effects of the Sulfolobus solfataricus chaperonin on the aggregation and inactivation upon heating of four model enzymes: chicken egg white lysozyme (one 14.4-kDa chain), yeast alpha-glucosidase (one 68.5-kDa chain), chicken liver malic enzyme (four 65-kDa subunits), and yeast alcohol dehydrogenase (four 37.5-kDa subunits). When the proteins were heated in the presence of an equimolar amount of chaperonin, 1) the aggregation was prevented in all solutions; 2) the inactivation profiles of the single-chain enzymes were comparable with those detected in the absence of the chaperonin, and enzyme activities were regained in the solutions heated in the presence of the chaperonin upon ATP hydrolysis (78 and 55% activity regains for lysozyme and alpha-glucosidase, respectively); 3) the inactivation of the tetrameric enzymes was completely prevented, whereas the activities decreased in the absence of the chaperonin. We demonstrate by gel filtration chromatography that the chaperonin interacted with the structures occurring during thermal denaturation of the model proteins and that the interaction with the single-chain proteins (but not that with the tetrameric proteins) was reversed upon ATP hydrolysis. The chaperonin had nonequivalent surfaces for the binding of the model proteins upon heating: the thermal denaturation intermediates of the single-chain proteins share Surfaces I, while the thermal denaturation intermediates of the tetrameric proteins share Surfaces II. ATP binding to the chaperonin induced a conformation that lacked Surfaces I and carried Surfaces II. These data support the concept that chaperonins protect native proteins against thermal aggregation by two mechanistically distinct strategies (an ATP-dependent strategy and an ATP-independent strategy), and provide the first evidence that a chaperonin molecule bears functionally specialized surfaces for the binding of the protein substrates.

Alcohol Dehydrogenase↗

PubMed1995

Anisotropy decay measurement of segmental dynamics of the anion binding domain in erythrocyte band 3.

Time-resolved anisotropy was utilized to detect nanosecond segmental motions of the band 3 intramembrane domain. Band 3 at lysine 430 was fluorescently labeled in ghost membranes by fluorescein or eosin maleimide treatment of intact human erythrocytes followed by hypotonic lysis. Single lifetimes for fluorescein (3.8-4.1 ns) and eosin (3.2-3.4 ns) were observed. Phase-modulation measurement of anisotropy decay indicated a segmental motion model, r(t) = exp(-t/tau 1c)[r infinity + (ro-r infinity) exp(-t/tau 2c)], defined by rotational correlation times corresponding to band 3 segmental motion (tau 1c, 30-70 ns) and rapid fluorescein motion in its binding pocket (tau 2c, 200-400 ps), and a residual anisotropy (r infinity, 0.23-0.28) describing hindered fluorescein motion. In PBS at pH 7.4, tau 1c, tau 2c, and r infinity were 44 ns, 307 ps, and 0.24, respectively, predicting a steady-state anisotropy of 0.24, in agreement with the measured value of 0.23. Factors that might influence band 3 structure/dynamics were examined. Whereas pH (range 5-10) had little effect on r(t), [NaCl] addition (0-150 mM) remarkably decreased tau 1c from 68 to 44 ns. The decrease in tau 1c correlated with solution ionic strength, and did not depend on osmolality (studied by mannitol addition), or specific anion interactions (comparing Cl, Br, F, SO4, citrate). The ionic strength effect was not observed in fluorescein-labeled carbonic anhydrase and trypsin-cleaved band 3, suggesting a specific effect on intact band 3. Anisotropy decay was relatively insensitive to external lectin or internal 2,3-DPG binding, but was sensitive to temperature, membrane fluidity, urea denaturation, fluid-phase viscosity, and aldehyde fixation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

The purification, cloning, and high level expression of a glutaredoxin-like protein from the hyperthermophilic archaeon Pyrococcus furiosus.

A protein has been purified to homogeneity from crude extracts of the hyperthermophilic archaeon Pyrococcus furiosus based on its ability to catalyze the reduction of insulin disulfides in the presence of dithiothreitol; the protein has a molecular mass of 24.8 kDa and a pI of 4.9, and it is highly heat-stable. The first 29 amino acid residues at the N terminus of the P. furiosus protein were determined by Edman degradation, and its gene was cloned in Escherichia coli. The amino acid sequence derived from the DNA sequence contains the CPYC sequence, which is typical of the active site of glutaredoxin (also called thioltransferase). The C-terminal portion of the P. furiosus protein, containing the conserved sequence, shows sequence similarity with glutaredoxins from different sources. The P. furiosus protein can reduce disulfide bonds in L-cystine in the presence of GSH (the thioltransferase activity) with an optimum pH of 8.0. The expression of the P. furiosus protein, with full activity, in E. coli at a very high level (21% of total soluble protein) is described; the recombinant protein was purified to homogeneity by merely two successive heat treatments and gel filtration chromatography. The features of the P. furiosus protein here described are discussed in light of the current knowledge about the ubiquitous family of protein disulfide oxidoreductases.

Amino Acid Sequence↗

PubMed1995

Laparoscopic versus conventional surgery for suspected appendicitis in women.

The diagnosis of appendicitis remains uncertain in female patients and laparoscopy has been suggested as a valid diagnostic tool. The laparoscopic approach has recently also been proposed for the treatment of acute appendicitis, though its real value is still under debate. A clinical and economic prospective evaluation of laparoscopic surgery over a 1-year period in female patients is reported. The study involved 38 patients presenting with signs of appendicitis and assigned to open (18) or laparoscopic surgery (20). The two groups were comparable as regards age and clinical presentation of the disease. The duration of the procedures was similar (60 min). Morbidity was comparable (3 vs 2). The ratio of negative appendectomy (50% vs 44%) was also similar, but the laparoscopic approach enabled a higher number of certain diagnoses (9/10 vs 3/8 p > 0.05). No significant differences were observed in the median postoperative stay (3 days for laparoscopy and 4 for surgery) or in the days needed to return to normal activity (15 vs 18). The cosmetic satisfaction was higher for the laparoscopic patients. The cost of the laparoscopic approach, however, was much higher than for conventional surgery. Our results suggest that laparoscopy is a useful diagnostic tool in female patients, but that laparoscopic appendectomy should be considered with some caution in times of restricted financial resources.

Acute Disease↗

PubMed1995

Optimum tomographic reconstruction parameters for HMPAO brain SPET imaging: a practical approach based on subjective and objective indexes.

The purpose of this study was to define an optimal strategy for the tomographic reconstruction procedure in routine brain single-photon emission tomography (SPET) studies, including the number of projections, filter function and matrix size. A set of projection data with different count densities was obtained from a technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) brain SPET acquisition from one volunteer. The projections were reconstructed with different filters and the quality of the reconstructed images was determined using both a subjective observer rating score and the Gilbert index. For each count density, the observers' choice corresponded to images with the lowest Gilbert index. The noise level in brain SPET sections was estimated and correlated with the fractal dimension. The results of this study indicate that although noise represents a fundamental component of brain SPET imaging, image quality also depends on the reconstructed spatial resolution. Image quality is satisfactorily described by fractal dimension. In addition the optimal filter function depends on the available count density. For high count levels, optimal reconstruction may be obtained by using a high-resolution matrix and a slightly smoother reconstruction filter. When count densities are low, best results are obtained by using a low-resolution matrix and a sharper filter. Finally, this study suggests that image quality is not influenced by the number of projections for equivalent count densities. These results were confirmed by 30 HMPAO brain SPET studies acquired in a routine clinical setting.

Brain↗

PubMed1995

Left ventricular diastolic filling in diabetes mellitus with and without hypertension.

Left ventricular diastolic filling by Doppler echocardiography was investigated in 84 diabetic patients without evidence of heart disease and in 84 normotensive nondiabetic age- and sex-matched control subjects. Diabetic patients were subdivided into two groups on the basis of the presence of arterial hypertension. Group 1 comprised 41 normotensive diabetic patients (19 men, 22 women, mean age 63.7 +/- 9.1 years); Group 2 comprised 43 hypertensive diabetics (15 men, 28 women, mean age 65.6 +/- 9.6 years). Doppler measures of diastolic filling were significantly altered in the two groups as compared with control subjects. Peak atrial flow velocity, velocity integral for the atrial filling period, and atrial filling fraction were increased, whereas the ratio of peak early to peak atrial flow velocity and the ratio of flow velocity integrals were decreased, especially in Group 2 patients. Thirteen patients in Group 1 (32%) and 17 in Group 2 (40%) had evidence of diastolic dysfunction, as assessed by the presence of at least two independent abnormal indices (outside age-corrected 95% confidence interval). In each group, patients with altered diastolic filling differed slightly from diabetic patients with normal Doppler indices, tending to increased wall thickness and left ventricular mass. In conclusion, diastolic filling of the left ventricle is frequently altered in diabetic patients and is adversely affected by arterial hypertension whose coexistence further impairs left ventricular relaxation.

Aged↗

PubMed1995

Esophageal achalasia: laparoscopic versus conventional open Heller-Dor operation.

BACKGROUND: The laparoscopic treatment of esophageal achalasia has recently been introduced, and the occasional reports in the literature seem to indicate considerable advantages for patients in terms of surgical trauma, postoperative discomfort, and appearance. As yet, however, no studies have directly analyzed the benefits and shortcomings of the new surgical technique by comparison with the conventional open procedure. The objective of our study was to review recent experience with the laparoscopic Heller-Dor operation (LAP-HD) at the Department of Surgery of Padua University and compare it with the traditional open Heller-Dor procedure (OPEN-HD) to assess early effectiveness in patients with primary esophageal achalasia. PATIENTS AND METHODS: The records of 17 patients who had LAP-HD and a matched group of 17 patients who had OPEN-HD were retrospectively reviewed. The duration of procedures, morbidity, several aspects of the postoperative course, and hospital costs were recorded and compared. Results of clinical follow-up and of manometric and pH-monitoring studies performed 6 months postoperatively were also evaluated in both patient groups. RESULTS: LAP-HD took longer than OPEN-HD (mean 178 versus 125 minutes). There was no mortality or major morbidity in either group. Postoperative pain and ileus and need for IV nutrition lasted a shorter time for LAP-HD patients (P < 0.0001). Consequently, the median postoperative hospital stay and the median interval before returning to normal activity were also shorter (4 and 14 days for the LAP-HD group versus 10 and 30 days for the OPEN-HD group, P < 0.0001). During follow-up, dysphagia recurred in 1 patient of the LAP-HD group and gastroesophageal reflux was registered in 1 patient of the OPEN-HD group. Lower esophageal sphincter pressure decreased significantly after both procedures. CONCLUSIONS: Laparoscopic management of achalasia leads to short-term results comparable to those of the well-established open technique. In view of the less severe surgical trauma and lower hospital cost, the laparoscopic approach is preferable, but long-term studies are needed.

Adult↗

PubMed1995

The lactase persistence/non-persistence polymorphism is controlled by a cis-acting element.

Lactase activity is present at high levels in the small intestine of some human adults and not others. This is due to a genetically determined polymorphism which affects the developmental regulation of the expression of the lactase gene. This polymorphism is of considerable interest in relation to cultural differences in nutrition but despite exhaustive studies, the molecular basis has not yet been found. It has not even been shown whether the sequence differences reside within or adjacent to the lactase gene itself or in a trans-acting factor. We have therefore exploited known DNA 'marker' polymorphisms within the exons of the lactase gene to examine the expression of the individual lactase mRNA transcripts from persistent and non-persistent individuals in order to determine whether the regulation is in cis or trans. Our results show that in certain lactase persistent individuals one allele of the lactase gene is expressed at much lower levels than the other and these individuals tend to have intermediate lactase activities. It is proposed that these people are heterozygous for the lactase persistence and non-persistence alleles and that this means that the nucleotide substitutions responsible for the lactase persistence/non-persistence polymorphism are cis-acting. This narrows down considerably the area of the genome that needs to be searched for the relevant sequence differences.

Adult↗

PubMed1995

A gene encoding a putative membrane protein homologous to the major facilitator superfamily of transporters maps upstream of the beta-glycosidase gene in the archaeon Sulfolobus solfataricus.

We have identified a gene encoding a putative membrane protein homologous to the major facilitator superfamily, mapping upstream of the lacS gene in Sulfolobus solfataricus. Permeases from this family mediate secondary transport and are widely distributed among eubacteria and eukaryotes; the finding of an archaeal member suggests that this mechanism of transport evolved before the divergence of the three living domains. We also report a transcriptional mapping of the gene cluster.

Amino Acid Sequence↗

PubMed1995

Radiolabelled lymphocyte migration in rheumatoid synovitis.

OBJECTIVES: To study the ability of technetium-99m hexamethyl propylene amineoxime (HMPAO) labelled lymphocyte scintigraphy to quantify synovial inflammation, and to analyse the kinetics of lymphocyte retention in the joints of patients with rheumatoid arthritis (RA). METHODS: After isolation of the lymphocytes, the cells were radiolabelled in vitro with 250 MBq 99mTc-HMPAO. The scans were performed 30 minutes, three hours and 20 hours after injection. RESULTS: An increase of the scintigram signal obtained at 20 hours was associated with a high joint swelling and joint pain score (F test = 3.07, p < 0.002), but not with the radiological score. A positive joint scintigram was predictive of active synovitis. Although the scintigram variation over time did not reach statistical significance, the kinetics of the scintigram signal tended to differ according to the disease duration: in early RA, active arthritis could be clearly imaged as early as 30 minutes, increased at three hours and the signal intensity persisted at 20 hours. In contrast, in long standing disease, the affected joints were imaged at 30 minutes, persisted unchanged at three hours, and the scintigram score decreased significantly at 20 hours. CONCLUSIONS: The study shows that 99mTc-HMPAO joint scintigraphy may be used to detect and to localise active rheumatoid arthritis.

Aged↗

PubMed1995

Secondary alcohol metabolites mediate iron delocalization in cytosolic fractions of myocardial biopsies exposed to anticancer anthracyclines. Novel linkage between anthracycline metabolism and iron-induced cardiotoxicity.

The cardiotoxicity of doxorubicin (DOX) and other quinone-containing antitumor anthracyclines has been tentatively attributed to the formation of drug semiquinones which generate superoxide anion and reduce ferritin-bound Fe(III), favoring the release of Fe(II) and its subsequent involvement in free radical reactions. In the present study NADPH- and DOX-supplemented cytosolic fractions from human myocardial biopsies are shown to support a two-step reaction favoring an alternative mechanism of Fe(II) mobilization. The first step is an enzymatic two-electron reduction of the C-13 carbonyl group in the side chain of DOX, yielding a secondary alcohol metabolite which is called doxorubicinol (3.9 +/- 0.4 nmoles/mg protein per 4 h, mean +/- SEM). The second step is a nonenzymatic and superoxide anion-independent redox coupling of a large fraction of doxorubicinol (3.2 +/- 0.4 nmol/mg protein per 4 h) with Fe(III)-binding proteins distinct from ferritin, regenerating stoichiometric amounts of DOX, and mobilizing a twofold excess of Fe(II) ions (6.1 +/- 0.7 nmol/mg protein per 4 h). The formation of secondary alcohol metabolites decreases significantly (Pi < 0.01) when DOX is replaced by less cardiotoxic anthracyclines such as daunorubicin, 4'-epi DOX, and 4-demethoxy daunorubicin (2.1 +/- 0.1, 1.2 +/- 0.2, and 0.6 +/- 0.2 nmol/mg protein per 4 h, respectively). Therefore, daunorubicin, 4'-epi DOX, and 4-demethoxy daunorubicin are significantly (P < 0.01) less effective than DOX in mobilizing Fe(II) (3.5 +/- 0.1, 1.8 +/- 0.2, and 0.9 +/- 0.3 nmol/mg protein per 4 h, respectively). These results highlight the formation of secondary alcohol metabolites and the availability of nonferritin sources of Fe(III) as novel and critical determinants of Fe(II) delocalization and cardiac damage by structurally distinct anthracyclines, thus providing alternative routes to the design of cardioprotectants for anthracycline-treated patients.

Alcohols↗

PubMed1995

Growth hormone response to growth hormone-releasing hormone (GHRH), insulin, clonidine and arginine after GHRH pretreatment in obese children: evidence of somatostatin increase?

To clarify the possible neuroendocrine mechanisms underlying the impairment in growth hormone (GH) secretion present in obesity, the GH response to GH-releasing hormone (GHRH, N = 6), insulin hypoglycemia (N = 6), clonidine (N = 7) and arginine (N = 8) after GHRH pretreatment (1 microgram/kg iv 2 h before the tests) was evaluated in 27 obese peripubertal children and in a group of normal-weight short-normal children (N = 26). Growth hormone-releasing hormone pretreatment and all further stimuli elicited a statistically significant GH response in both obese and short-normal children; in the latter group arginine did not induce a significant GH response. No differences were found among the GH responses after the second stimuli in obese children, while in short-normal children the arginine peak and area values were lower than after GHRH and clonidine. Comparison between the two groups showed similar baseline but higher stimulated GH levels in normal-weight children after all tests except arginine, after which no difference was present. In conclusion, the neuroregulation of GH release seems to be similar qualitatively in normal-weight and obese youngsters; the different behavior observed after arginine, which is supposed to act through somatostatin inhibition, might be due to a chronic increase in somatostatinergic tone responsible for the lower stimulated GH levels in obesity.

Adolescent↗

PubMed1995

Sequence of Asr2, a member of a gene family from Lycopersicon esculentum encoding chromosomal proteins: homology to an intron of the polygalacturonase gene.

Asr is a family of genes regulated by abscisic acid, stress and ripening in tomato. Asr2, a recently reported member of this family, has been further characterized through sequencing of a genomic clone. We report the sequencing of 2029 bp of Asr2, spanning its AT-rich (62%) upstream region with probable regulatory functions. This region displays several candidate TATA and CAAT boxes that might be involved in transcription initiation, as well as a motif similar to one previously reported to be responsible for induction by ABA. Apart from that, we found a 108-bp stretch from the 3' non-coding region which displays a high homology (92%) to a region within intron 6 of the polygalacturonase gene, which, like Asr2, is expressed in ripening tomato fruit. This striking similarity suggests the presence of either a conserved regulatory motif or an abundant mobile element.

Base Sequence↗

PubMed1995

Changes in some egg components and analytical values due to hen age.

The influence of hen age on some egg characteristics was studied. Two commercial breeds of brown hens, namely Warren and Hy-Line, were considered at seven different ages. The variables analyzed were the weights of yolk and thick and thin albumen, pH, and the concentration of glucose, uridine, and uric and pyroglutamic acids of separated yolk and albumen. Albumen and yolk average weights and the proportion of yolk in the edible part of egg increased with hen age, whereas the average ratio of thick to thin albumen was not influenced by the progress of the laying cycle. Glucose, uridine, and uric acid were also not influenced by hen age. Pyroglutamic acid, which is detectable in yolk and not in the albumen of a fresh egg, showed a characteristic trend in yolk. Its concentration dramatically increased in the middle of the laying cycle and then decreased to values close to those observed in eggs of the young layers.

Aging↗

PubMed1995

[Nonvascular interventional radiology in the treatment of post-liver transplant complications. The clinico-radiological correlations and technical considerations].

Eleven patients, included in a series of 105 orthotopic liver transplant recipients, underwent interventional radiologic procedures for post-operative complications. Seven patients had obstructive jaundice, three patients had sepsis, and one patient was bleeding from the T-tube. Cholangiography, performed in 9/11 patients, demonstrated stenosis of the anastomosis in six cases, stenosis of the intrahepatic biliary tree in one case, and stenosis of both tracts in the remaining two cases. Four patients were treated with bilioplasty (from 1 to 5 sessions), using balloon catheters (8-10 mm) followed by stones removal in one case, and by the placement of a metallic stent in another case. The follow-up ranged from one to three years: no biliary stasis occurred, during that period, in these patients. Another patient with recurrent cholangiocarcinoma of the biliary anastomosis, treated with Carey-Coons endoprosthesis and brachytherapy, died four months later without jaundice. In the three patients with sepsis and in the patient with bleeding from the T-tube, intra- or extra-hepatic (in one case) multiple abscesses were demonstrated. The conservative treatment with the placement of percutaneous drainage catheters, associated with internal biliary drainage in two cases, allowed complete symptoms resolution. The technical success obtained in all patients confirmed the effectiveness of interventional radiology in the treatment of biliary complications after liver transplant, thus avoiding the need of surgical reintervention.

Cholangiography↗

PubMed1995

Multimedia presentation of lung sounds as a learning aid for medical students.

New educational technologies might help to compensate for the decrease in time and emphasis dedicated to physical examination in medical training. This may, in particular, be applicable for improving the skills in auscultation of the chest. We investigated whether a multimedia presentation of acoustic and graphic characteristics of lung sounds could improve the learning of pulmonary auscultation by medical students, in comparison with conventional teaching methods. We studied 48 medical students without clinical experience, who had received conventional formal teaching on chest examination. Chest auscultation skills were evaluated using an inaccuracy score for the student's auscultation report on three patients, selected according to a standardized procedure. After a baseline evaluation, 27 students in groups of 5-10, participated in a multimedia seminar on lung sounds during which digitized lung sounds were played and the corresponding time-expanded waveform and frequency spectrum were commented on and displayed on a computer. The remaining 21 students received conventional bedside training, acting as control group. The following week, all the students underwent a second evaluation of chest auscultation skills. No differences in the inaccuracy score were observed between the two groups in the preliminary test. However, in the second postintervention assessment, the inaccuracy score of the students who had followed the seminar (11.2 +/- 1.3 points) was significantly lower than that of the controls (16.6 +/- 1.6 points). The answers to a feedback questionnaire confirmed that the great majority of the students found the association of the acoustic signals with their visual image to be useful for learning and understanding lung sounds.(ABSTRACT TRUNCATED AT 250 WORDS)

Attitude of Health Personnel↗

PubMed1995

[Laparoscopic treatment of hepatic cysts].

Laparoscopic treatment of simple hepatic cysts is reported. Recent indications to conservative surgical treatment for this benign disease are considered and different therapeutic options are analyzed. Surgical technique adopted in two cases observed is illustrated. In conclusion, the Authors consider laparoscopic treatment as an effective method for a mini-invasive surgical approach.

Aged↗

PubMed1995

The efficacy and safety of moguisteine in comparison with codeine phosphate in patients with chronic cough.

We conducted a multicentre, double-blind, parallel group study to compare the clinical efficacy of a new antitussive drug, moguisteine (100 mg t.i.d.), to that of a reference standard, codeine (15 and 30 mg, t.i.d.). Both drugs were given orally for a period of two days. A group of 119 patients (mean age 54 yrs; 61 females and 58 males) with chronic, dry or slightly productive cough, associated with various respiratory disorders (including chronic obstructive pulmonary disease, respiratory malignancies and pulmonary fibrosis) were enrolled at six participating centres. The percentage reduction in the number of morning coughs over a period of 6 h after the first administered dose compared to baseline assessment, was 21% with moguisteine (n = 39), 28% with codeine 15 mg (n = 38), and 29% with codeine 30 mg (n = 36). Differences between treatments were not significant. The percentage reduction in the number of nocturnal coughs per hour, after the last evening dose compared to baseline assessment, was 33, 46 and 52%, respectively. Subjective assessments (patients' visual analogue scale scores of cough frequency, cough intensity and sleep disturbance, and investigators' ranking of cough severity) indicated that there was a similar improvement in cough symptoms in all treatment groups. Adverse events were observed in two patients on moguisteine, three on codeine 15 mg, and five on codeine 30 mg. No event was serious, but discontinuation of treatment was required in two patients on codeine 30 mg. The results of our study suggest that moguisteine 100 mg t.i.d. is safe, and seems to have an antitussive activity similar to that of codeine 15-30 mg t.i.d.

Administration, Oral↗