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Biomedical subjects

M Rossi

Publications and source records attributed to M Rossi.

At least 397 records · Page 22Linked to original sources
PubMed1994

Histamine and exercise-induced hypoxemia in highly trained athletes.

To determine whether exercise-induced hypoxemia in extreme athletes results from an increase in histamine level during maximal incremental exercise, seven young athletes [YA; age 22.2 +/- 1.23 (SE) yr] and seven master athletes (MA; age 66.2 +/- 2.94 yr), all of whom were known to develop exercise-induced hypoxemia, were compared with age-matched control groups (young controls and older controls, respectively). During maximal incremental exercise, blood samples for arterial blood gas analysis and for plasma and total histamine were drawn at rest and at 50, 75, and 100% of maximal O2 uptake. The percentage of histamine released (%H) was calculated from plasma and total histamine samples. In all athletes (MA and YA groups), exercise induced an increase in %H with a concomitant decrease in arterial PO2 (PaO2); in control groups there was no change in either histamine levels or PaO2. When the data for the YA and MA groups were combined, a correlation was observed between the increase in %H and the drop in PaO2. Nevertheless, further studies are required to establish whether histamine plays a causative role in hypoxemia or is a response to injury.

Adult↗
PubMed1994

Gene expression of a thermostable beta-galactosidase in mammalian cells and its application in assays of eukaryotic promoter activity.

The gene (lacS) encoding a thermostable beta-galactosidase enzyme (Ss beta-gal) from the archaebacterium Sulfolobus solfataricus has been cloned and expressed in simian CV1 and murine NIH3T3 cell lines. The recombinant protein is an active enzyme that shows the same properties of thermophilicity and thermostability as the wild-type Ss beta-gal and has no cytotoxic effect on the host cells. Its possible use as a reporter gene is also proposed, and a comparison with other reporter gene systems is made.

3T3 Cells↗
PubMed1994

[Effects of rehabilitation on cardiovascular autonomic function in ischemic cardiopathy].

METHODS: Twenty patients with uncomplicated myocardial infarction randomized in two groups (group 1 and 2) of ten patients were investigated. Only group 1 trained four months according to a protocol of rehabilitation, whereas patients of group 2 followed their usual activity (control group). The autonomic cardiovascular function was estimated by Ewing's tests, that evaluate the variations of heart rate and blood pressure during deep breathing. RESULTS: Our data showed an increase of parasympathetic tone in group 1 (Valsalva ratio 1.55 +/- 0.28 vs 1.36 +/- 0.28, p < 0.01; variation in heart rate during deep breathing 17.3 +/- 4.6 vs 13.3 +/- 4.2). The sympathetic activity tests showed no significant difference after training. On the other hand, group 2 showed no significant difference in sympathetic and parasympathetic activity. CONCLUSIONS: In patients with uncomplicated myocardial infarction physical training increases the parasympathetic activity; as shown in the literature, such an increase can have clinical and prognostic importance, since improves cardiac performance and reduces the risk of sudden death from arrhythmic events.

Aged↗
PubMed1994

[Carbon dioxide as an intra-arterial contrast agent in echography: a technic for its preparation and the preliminary results in assessing hepatocarcinoma vascularization].

This paper reports on an original method to prepare a contrast agent consisting of CO2 microbubbles to be injected i.a. during ultrasound examinations (ultrasound angiography-USA), whose value was investigated in the study of tumor neovascularity in HCC patients. Thirty-five HCC patients underwent USA. CO2 was drawn out from a gas container under pressure and, through a sublimation process, made available in predetermined quantities in test tubes. USA was performed during angiography in 9 cases and immediately before arterial chemoembolization in the other 26 cases. In 51 lesions vascularity was evaluated with conventional angiography, USA and lipiodol CT. USA demonstrated lesion hypervascularity in 91% of cases, as confirmed by lipiodol CT (88%), versus 72.4% of angiography. In 3 of 35 patients USA demonstrated 6 more lesions undetected by other modalities: two of them were proved to be HCC and adenomatous hyperplasia at percutaneous biopsy. USA is a cost-effective procedure, which is easy to perform during conventional angiography: it is more sensitive than conventional angiography in the study of lesion neovascularity and can help plan lesion management, anticipating the results of chemoembolization. The role of USA in the diagnosis and treatment of HCC is, however, still to be defined.

Aged↗
PubMed1994

[Late posttraumatic diaphragmatic hernia. A clinical case report].

On the basis of the observation of one case of delayed presentation of traumatic diaphragmatic rupture of the left side with a late diaphragmatic hernia, the authors examine the evolution of the occurrence of this pathology during the last 20 years. The clinical signs and the modality of presentation of the lesions of delayed diagnosis appear absolutely non specific. Incorrect interpretation of the X-ray or only intermittent hernial symptoms are frequent reasons for incorrect diagnosis. Also the initially non recognition of the possible manifestation of the diaphragmatic hernia following blunt or penetrating injuries is usually because the practitioner has not sought it. The diaphragmatic domes must be systematically explored during the laparotomy or thoracotomy performed for thoraco-abdominal trauma. Surgical treatment of long-standing post-traumatic diaphragmatic hernia is the same as that applicable in the recent hernias.

Accidents, Traffic↗
PubMed1994

[Limited surgery in cancer of the hypopharynx and cervical esophagus: role of autotransplants of the intestinal loop and skin flaps].

The cervical esophageal region can be involved by several cancer types as primary malignancies of the hypopharynx and cervical esophagus, locally advanced tumors of the larynx and thyroid, and neoplastic recurrence after laryngectomy for cancer. These situations often require complex surgical procedures, and the integrated use of multiple surgical techniques or multistage operations. It is often a limit-type surgery that requires free loop intestinal autotransplants, local and regional skin flaps, and peduncle myocutaneous flaps, and therefore requires specific skill not only in general and thoracic surgery but also in head and neck surgery, plastic surgery and microsurgery. This paper summarizes the experience in the field of cervical esophagus replacement with jejunal free loop autotransplant (23 cases) and cutaneous or myocutaneous flaps (23 cases) at the "Centro Regionale Veneto per le Malattie dell'Esofago" from 1980 to 1993.

Esophageal Neoplasms↗
PubMed1994

[Transjugular intrahepatic porto-systemic shunt (TIPS): indications and results].

This study was aimed at describing some technical features of the transjugular portosystemic shunt (TIPS). December 1991 to November 1993, fifty-five TIPS were performed in our department. The right internal jugular vein, which is the most direct path to the inferior vena cava, was punctured in 48 cases, the left one in seven cases. The right suprahepatic vein was catheterized in 43 cases, and the median suprahepatic vein in 12 cases. The puncture of the portal vein was performed in 21 cases in the right portal branch, in the left one in 23 cases, and in the portal bifurcation in 11 cases. In all cases in which the puncture site was questionable, an X-ray exam with lateral or oblique projection was performed, to be sure that the needle had entered the intrahepatic portion of the portal vein. A landmark to locate the portal system, such as a catheter in the hepatic artery, a skin landmark or a metallic coil near the porta, were positioned in 30 patients. Particularly, in 20 patients, a 0.018-inch guidewire with platinum tip was placed at the bifurcation; in seven cases a 3F catheter was advanced over the guidewire, to visualize the portal bifurcation directly with contrast medium injection. In our experience, a total number of 83 stents were positioned in 55 patients: 53 Wallstents, 13 Palmaz stents, and 17 Strecker-Nitinol stents. One single stent was placed in 31 patients, two stents in 21 patients, three stents in two patients, and, finally, four stents were positioned in one patient. In our series the technical success rate was 100%. The use of a metallic landmark significantly decreased procedures duration, ranging 40 minutes to 2 hours, and, above all, it allowed for significantly fewer puncture attempts, which varied from a minimum of 1-2 in 80% of cases, to a maximum of 20 especially in these patients with ascitis and with small and hard liver.

Procedural Sedation↗
PubMed1994

Flexistap BC: a new flexible circular stapler for endoscopic surgery.

This article presents a new stapler characterised by a flexible arm and interchangeable cartridges. The stapler's flexibility and availability in different lengths up to 60 cm permits the placing of sutures even at significant distances from the point of entry; furthermore it is possible to perform more sutures on the same patient by replacing the cartridges. The author discusses the technical features of the instrument in detail.

Anastomosis, Surgical↗
PubMed1993

Analysis of lactase processing in rabbit.

The proteolytic processing of rabbit intestinal lactase-phlorizin-hydrolase (LPH) was studied by pulse-chase and continuous labeling experiments in organ culture from 15-day-old rabbits in the presence of glycosylation and processing inhibitors. Monensin and brefeldin A inhibited the two proteolytic cleavages of the precursor indicating that they are post-Golgi events as previously reported for the unique cleavage of LPH in man. The inhibition was not related to a concomitant alteration glycosylation; in fact, if trimming was blocked by MDNM the abnormal glycosylated precursor was proteolytically processed normally. Finally the use of the anti-microtubular drug colchicine strongly inhibited both cleavages and caused accumulation of the complex-glycosylated precursor form the brush border fraction indicating that proteolytic events depend on intact microtubule (transport).

Animals↗
PubMed1993

Lactase-phlorizin hydrolase and aminopeptidase N are differentially regulated in the small intestine of the pig.

The longitudinal expression of two brush-border enzymes, lactase-phlorizin hydrolase (EC 3.2.1.23/62) and aminopeptidase N (EC 3.4.11.2), was studied in the small intestine of the post-weaned pig. Whereas the level of mRNA, encoding aminopeptidase N (relative to that of beta-actin), only varied moderately from the duodenum to the terminal ileum, the amount of lactase-phlorizin hydrolase mRNA exhibited a sharp maximum in the proximal jejunum. For both enzymes, the level of protein synthesis, studied in cultured mucosal explants, correlated well with the level of mRNA, and no major variation in post-translational processing or intracellular transport was observed along the intestine. The mRNA/specific-activity ratio for both enzymes was markedly (3-5-fold) higher in the duodenum and proximal jejunum, compared with the ileum. This indicates an increased proximal turnover rate, most likely caused by the presence in the gut lumen of pancreatic proteases. In neonatal animals, the level of mRNA for lactase-phlorizin hydrolase in both proximal and distal regions of the intestine was of the same magnitude as in the proximal jejunum of the post-weaned pigs. Our results point to two mechanisms that affect the expression of lactase-phlorizin hydrolase in the pig during development: (1) a primary regulation at the level of mRNA (predominantly in the ileum); (2) an increased rate of turnover of the enzyme, mainly in the duodenum and proximal jejunum, and most likely due to an increased secretion into the gut lumen of pancreatic proteases (a mechanism also affecting aminopeptidase N and probably other brush-border enzymes as well).

Aging↗
PubMed1993

In vitro biosynthesis of lactase in suckling and adult rabbits. Regulatory mechanisms involved in the decline of the lactase activity.

Steady state forms, levels and the in vitro biosynthesis of lactase-phlorizin hydrolase (LPH) proteins have been studied in proximal and middle intestine of suckling and adult rabbits. In most adult tissues the lactase activity and the LPH protein content were low and the synthesis rate of the 200 kDa lactase precursor was reduced in comparison to suckling tissues. In a few tissues with low enzymatic activity the LPH protein content was relatively high, and high lactase synthesis occurred. In addition, the ratio (labeled lactase)/(lactase protein) was lower in the middle jejunum of the adult rabbit than in the proximal region. Both decreased synthesis of LPH precursor and increased turnover or inactivation of the enzyme may cause the decline of the lactase activity.

Animals↗
PubMed1993

Crystallization and preliminary X-ray analysis of an NAD(+)-dependent alcohol dehydrogenase from the extreme thermophilic archaebacterium Sulfolobus solfataricus.

An NAD(+)-dependent alcohol dehydrogenase from the extreme thermophilic archaebacterium Sulfolobus solfataricus has been crystallized in the holo-enzyme and apo-enzyme forms. Crystals of the holo-enzyme grow from 2-methyl-2,4-pentanediol at pH 8.4 with the addition of NADH and at pH 7.0 with the addition of NADH and dimethyl sulphoxide. Crystals of the apo-enzyme grow at pH 6.3 from a mixture of polyethylene glycol 4000 and propan-2-ol. The holo-enzyme crystallizes in C2 with a dimer in the asymmetric unit, however the crystals are twinned and unsuitable for data collection. The apo-enzyme crystallizes in I4(1)22 (a = 126.82 A, b = 118.95 A) with a monomer in the asymmetric unit, and the single crystals diffract to 2.8 A.

Alcohol Dehydrogenase↗
PubMed1993

Crystallization and preliminary X-ray analysis of the beta-galactosidase from the extreme thermophilic archaebacterium Sulfolobus solfataricus.

The beta-galactosidase from the extreme thermophilic archaebacterium Sulfolobus solfataricus has been crystallized from polyethylene glycol 4000 in the presence of sodium acetate and acetate buffer at pH 4.6. The protein crystallizes in P3(1)21 or P3(2)21 (a = 169.4, c = 98.29) and the crystals diffract beyond 2.5 A. The measured crystal density (approximately 1.28 g/cm3) is consistent with the presence of a tetramer (molecular mass 240 kDa) in the asymmetric unit. The specific volume of the crystals is 1.7 A3/Da, indicating a solvent content by volume of only 27%, which is amongst the lowest values observed for protein crystals, and indicates virtual close-packing of the tetramers.

Crystallization↗
PubMed1993

Structural synaptic correlate of long-term potentiation: formation of axospinous synapses with multiple, completely partitioned transmission zones.

Synapses were analyzed in the middle molecular layer (MML) and inner molecular layer (IML) of the rat dentate gyrus following the induction of long-term potentiation (LTP) by high-frequency stimulation of the medial perforant path carried out on each of 4 consecutive days. Potentiated animals were sacrificed 1 hour after the fourth high frequency stimulation. Stimulated but not potentiated and implanted but not stimulated animals served as controls. Using the stereological disector technique, unbiased estimates of the number of synapses per postsynaptic neuron were differentially obtained for various subtypes of axospinous junctions: For atypical (giant) nonperforated synapses with a continuous postsynaptic density (PSD), and for perforated ones distinguished by (1) a fenestrated PSD and focal spine partition, (2) a horseshoe-shaped PSD and sectional spine partition, (3) a segmented PSD and complete spine partition(s), and (4) a fenestrated, (5) horseshoe-shaped, or (6) segmented PSD without a spine partition. The major finding of this study is that the induction of LTP in the rat dentate gyrus is followed by a significant and marked increase in the number of only those perforated axospinous synapses that have multiple, completely partitioned transmission zones. No other synaptic subtype exhibits such a change as a result of LTP induction. Moreover, this structural alteration is limited to the terminal synaptic field of activated axons (MML) and does not involve an immediately adjacent one (IML) that was not directly activated by potentiating stimulation. The observed highly selective modification of synaptic connectivity involving only one particular synaptic subtype in the potentiated synaptic field may represent a structural substrate of the long-lasting enhancement of synaptic responses that characterizes LTP.

Animals↗