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Biomedical subjects

S Rossi

Publications and source records attributed to S Rossi.

At least 235 records · Page 13Linked to original sources
PubMed1996

A non-isothermal bioreactor utilizing immobilized baker's-yeast cells: a study of the effect on invertase activity.

The behaviour of the enzyme invertase, located on the cell wall of baker's-yeast cells and entrapped in a gelatin membrane, was studied under isothermal and non-isothermal conditions. The reaction rate linearly increased with the applied transmembrane temperature gradient, with reference either to the average temperature or to the temperature on the warm side of the catalytic membrane. These results were obtained both when the bioreactor was operated under conditions of closed volumes and when the substrate-containing solutions are recirculated. The mathematical relationships have been elaborated between the temperatures read in the working solutions and those on the two faces of the catalytic membrane. Since the temperature difference across the membrane is smaller than that indicated by the thermocouples, the observed effects are greater than expected. The potential advantages of the use of a non-isothermal bioreactor in processes of industrial interest are discussed.

Biotechnology↗
PubMed1996

Serial monitoring of soluble interleukin-2 receptor as a rapid marker of cytomegalovirus infection and response to antiviral therapy.

Serial sIL-2R serum levels were evaluated as an indicator of cytomegalovirus infection and response to antiviral therapy. All cases of post-transplant CMV infection or disease were studied over a 2.5-year period with serial sIL-2R serum levels monitored daily post-transplant until discharge, during each inpatient admission and with each outpatient laboratory analysis. Mean sIL-2 levels +/- S.E.M. rose from a baseline level of 3662 +/- 321 U/ml to 11657 +/- 3311 U/ml at the time of diagnosis. Serum sIL-2R concentrations were significantly elevated from baseline as early as 14 days prior to diagnosis of CMV. Mean peak sIL-2R levels occurred an average of 4 days after the initiation of ganciclovir therapy and remained significantly elevated for an average of 20 days of treatment. Serum sIL-2R levels in patients with resolved CMV returned to within 20% of baseline after 20 days of therapy. These data support the idea that serial monitoring of sIL-2R serum levels may be useful adjunctively in the diagnosis of CMV as well as determining the response to and duration of antiviral therapy.

Adult↗
PubMed1995

Neuromagnetic fields of the brain evoked by voluntary movement and electrical stimulation of the index finger.

Neuromagnetic fields from the left cerebral hemisphere of five healthy, right-handed subjects were investigated under two different experimental conditions: (1) electrical stimulation of the right index finger (task somatosensory evoked fields, task SEF's), and (2) voluntary movement of the same finger referred to as movement-related fields, (MRFs). The two conditions were, performed in random order every 5-8 s. In addition, the task SEF's were compared to control SEF's recorded at the beginning of the experiment in order to find the optimal dewar position for localizing the central sulcus. The magnetic signals of the sources corresponding to the main components of the somatosensory evoked fields (early ones at 24 ms and at 34 ms, and late ones after 50 ms) and movement-related fields (motor field, MF and movement-evoked field I-MEF I) were mapped and localized by means of a moving dipole model. In four out of five subjects the MEF I dipoles were found to be located deeper than the early task SEF dipoles. In addition, all of the task SEF's components were found to exhibit larger amplitudes than the control SEF's components. The results are discussed in respect to the ability to selectively analyze contributions of mainly proprioceptive (area 3a) and cutaneous (area 3b) areas in the primary somatosensory cortex using magnetoencephalography. An additional finding of the study was that all of the task SEF's components were found to exhibit larger amplitudes than the control SEF's components.

Adult↗
PubMed1995

Acute biochemical variations induced by two different calcium salts in healthy perimenopausal women.

Despite the potential utility of calcium supplementation and the availability of many calcium supplements in the market, there are few data concerning the absorbability of different calcium salts in different conditions. We have compared the acute metabolic responses following oral administration of calcium citrate (CC) or calcium gluconolactate and carbonate (CGC) given to 20 healthy perimenopausal women (aged 48-55 years). Ten women received two effervescent tablets of CC (each containing 500 mg of calcium) and 10 women received two effervescent tablets of CGC (each containing 500 mg of calcium). Before and on an hourly basis for 6 hours, serum total and ionized calcium, phosphate, and immunoreactive parathyroid hormone (iPTH) were measured. Urinary calcium and creatinine were also measured. Both calcium salts induced significant increase in serum total and ionized calcium and in urinary calcium excretion; they also significantly reduced circulating levels of iPTH. The analysis of ionized calcium and iPTH response curves to CC and CGC administration revealed a significantly greater bioavailability of CC compared with CGC. Our data suggest that CC could be prefered to CGC for its characteristics of absorbability and bioavailability.

Calcium↗
PubMed1995

Diagnostic value of ultrasound analysis and bone densitometry as predictors of vertebral deformity in postmenopausal women.

Bone fractures depend not only on bone density, but also on bone quality. Ultrasound (US) has been proposed as a technique for evaluating skeletal status. Speed of sound (SOS) and broadband ultrasound attenuation (BUA) are the US properties currently used to assess bone strength and fragility. In 304 postmenopausal women (age 58.8 +/- 5.5 years) we measured: bone mineral density (BMD) of the lumbar spine (by dual-energy X-ray absorptiometry), SOS, BUA and Stiffness in the os calcis (using an Achilles machine). In all subjects we performed lateral lumbar and thoracic radiographs. Morphometric parameters were derived by measuring the anterior, middle and posterior height of each vertebral body, to obtain a semiquantitative grading of vertebral fractures as follows: 0, no vertebral deformity; 1, any vertebral height reduced between 20% and 25%; 2, any vertebral height reduced between 25% and 40%; 3, any vertebral height reduced more than 40%. On the basis of the number and severity of vertebral deformities the women were divided into: group 1 (n = 79), normal; group 2 (n = 80), mild; group 3 (n = 85), moderate; and group 4 (n = 60), severe. Mean values of SOS, BUA, Stiffness and BMD were significantly lower (p < 0.001) in women with vertebral deformity than in normals. In the whole population SOS, BUA and Stiffness values were significantly correlated with BMD. SOS, BUA and Stiffness values were significantly decreased (p < 0.001) with vertebral deformity, as was BMD. Receiver operating characteristic (ROC) curve analysis showed BMD to be slightly better than Stiffness in discriminating among groups. Logistic regression analysis showed that BMD, BUA, SOS and Stiffness were independent predictors of vertebral fracture risk. Ultrasound parameters were still significant independent predictors of vertebral fracture even after adjusting for BMD.

Absorptiometry, Photon↗
PubMed1995

Influence of mucin type on polymer-mucin rheological interactions.

There are numerous in vitro methods with which to investigate the mucoadhesive properties of polymers. One recent method is based on the measurement of rheological interactions between polymer and mucin, which implies the use of mucins isolated from the mucous tissue. The extraction and purification of glycoprotein fraction, which is responsible for rheological interaction, can modify the native structure of mucin or spoil it with exogenous substances. Therefore the particulars of the mucin employed (origin, purification grade, the effect of further treatments such as freezing or freeze-drying) are likely to be critical for the interaction. The aim of this work was to compare some commercial mucins of differing origin and grade of purification for their rheological interaction with well-known mucoadhesive polymers (polyacrylic acid and sodium carboxymethylcellulose). For polyacrylic acid, which is sensitive to ions, we found rheological interaction to be strongly influenced by mucin type. The removal of ions, with dialysis, improved the interaction. For sodium carboxymethylcellulose, which is less sensitive to ions, rheological interaction proved to be less dependent on mucin type and improved upon glycoprotein solubilization.

Acrylic Resins↗
PubMed1995

Cervical and scalp recorded short latency somatosensory evoked potentials in response to epidural spinal cord stimulation in patients with peripheral vascular disease.

Somatosensory evoked potential (SEP) studies were performed in 14 patients with peripheral vascular disease who received epidural spinal cord stimulation (SCS) for chronic pain relief of the lower limbs. Signals were amplified and filtered between 20-2000 Hz and 200-2000 Hz to better identify activities in the high frequency range. In 7 patients bit-colour maps were also computed. In all the patients a homogeneous short-latency scalp evoked potential with a prevalent diphasic shape (P1-N1) was recorded. In all our scalp records, even with the wide bandpass, small short-latency positive deflections were observed on the descending front of the first major positive wave and they were better defined as a series of up to 6 wavelets, preceding the major negative scalp wave in the tracings filtered through the narrow bandpass. They appeared in an interval ranging from 5.5 to 15.6 msec. Bit-colour maps showed consistent positive fields, with a maximum at the vertex, starting mainly at about 5.5 msec; in 3 patients, a prominent positivity between 8.5 and 10.5 msec was recorded followed by smaller components preceding the major positive-negative (P1-N1) complex. More synchronous volleys during direct SCS produced clear short-latency SEPs. Although they were of larger amplitude, we regarded them as corresponding to those described by previous authors obtained by stimulation of nerves of the lower limbs, and probably arising from subcortical structures.

Adult↗
PubMed1995

Protective actions of L-carnitine and acetyl-L-carnitine on the neurotoxicity evoked by mitochondrial uncoupling or inhibitors.

The mechanism for the pathological increase in cell death in various disease states e.g. HIV immunodefficiency or even ageing or Alzheimer's disease, occurs by complex and as yet undefined mechanism(s) related to immunological, virological or biochemical disturbances (i.e. energy depletion, oxidative stress, increased protein degradation). We have studied mitochondrial uncoupling or inhibitor toxicity on neurones at the cellular level and at the mitochondrial level using rhodamine (Rh123) and 10-nonylacridine orange (NAO) fluorescence with confocal microscopy. Blockade of the mitochondrial chain complexes at various points was studied. The possible protective effects of the compound L-carnitine, which plays a central role in mitochondrial function, was tested in this form of neurotoxicity. It appears that L-carnitine and its acetylated form, acetyl-L-carnitine, can attenuate the cell damage, as assessed by lactate dehydrogenase (LDH) release, evoked by the uncoupler, p-(trifluoromethoxy)phenylhdyrazone (FCCP), or by the inhibitors, 3-nitropropionic acid (3-NPA) or rotenone. Further, the FCCP-induced inhibition of Rh123 uptake was antagonized by the preincubation of cells with L-carnitine. Since such neurotoxic mechanisms may be operating in the various pathological forms of myotoxicity and neurotoxicity, these observations suggest potential for a therapeutic approach.

Acetylcarnitine↗
PubMed1995

Differential distribution of hepatitis C virus genotypes in patients with and without liver function abnormalities.

Hepatitis C virus (HCV) infection persists for an indefinite length of time in a major proportion of patients, inducing chronic liver lesions that evolve to cirrhosis and hepatocellular carcinoma (HCC) in approximately 20% of cases. We studied HCV viremia and genotypes by reverse transcription-polymerase chain reaction (RT-PCR) in 341 consecutive anti-HCV-positive patients. Of these, 167 patients had persistently normal or near normal alanine aminotransferase (ALT) levels (fluctuations < or = 5 IU above the upper limit of normal); the remaining 174 patients presented with elevated ALT and histological evidence of chronic liver disease. Seventy percent of patients with normal ALT values had circulating HCV RNA despite the absence of biochemical indicators of liver damage and mild histological forms of chronic hepatitis were detected in most patients who underwent liver biopsy. Isolated genotype III infection was significantly more prevalent in this patient group with respect to control patients with abnormal ALT values (70% vs. 39%; P < .001). Conversely, isolated genotype II was more frequently found in patients with elevated ALT values and evidence of chronic liver disease (45% vs. 23%; P < .01) and it was progressively more represented in advanced liver disease, such as cirrhosis and HCC. Virological features of HCV infection might be associated with different clinical manifestations, suggesting a potential prognostic significance on disease outcome.

Adolescent↗
PubMed1995

[Bioadhesives: rationale, state of the art and therapeutic potential].

Pharmaceutical research is going on the way to formulate drugs in dosage forms and delivery systems able to improve their biopharmaceutical properties. For some routes of administration, among them the transmucosal ones, such improvements may be reached by increasing the time and the nature of the contact between mucosal tissues and drug dosage forms via chemical or physical bioadhesive links. Biopharmaceutical AFI Study Group efforts were oriented in analyzing the actual state of the art in the field of bioadhesive drug delivery. Rationals of use of drug dosage forms with bioadhesive properties, analytical method of control of bioadhesion (both in vitro and in vivo) and therapeutical potentialities are the matter of this review.

Animals↗
PubMed1994

Regulation of protein kinase A subunits during germination of Mucor rouxii sporangiospores.

Levels of protein kinase A (PKA) subunits and of cAMP have been measured during aerobic germination of the sporangiospores of the dimorphic fungus Mucor rouxii; further, the holoenzyme and its catalytic (C) and regulatory (R) subunits have been visualized through sucrose gradient centrifugation. Sporangiospores contain around 0.06 microM of a dimeric holoenzyme species of 5.5 S and a sixfold excess of a free R subunit of 2.7 S. Both these species are proposed to be derived by proteolysis from the native forms. Enzymic activity at this stage is highly inhibited, as demonstrated with permeabilized cells. Immediately upon germination, and after a transient increase in cAMP concentration from 10 microM to 90 microM, C-subunit levels fall to 30%. After the onset of germination, the specific activity and concentration of both the 5.5 S holoenzyme species and the 2.7 S species of free R subunit decrease in parallel to the increase in total protein and volume. Net synthesis of C and R subunits to form a native holoenzyme species of 8.8 S is apparent 4 h onwards after germination. A significant increase in cellular concentration is observed at 6 h. At 7 h of growth, when germ-tube emission is complete, the holoenzyme concentration is around 0.23 microM; there is almost no free R subunit and the intracellular concentration of cAMP is around 3 microM. A role for PKA during germination and morphogenesis is discussed.

Cell Membrane Permeability↗