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Biomedical subjects

M Corso

Publications and source records attributed to M Corso.

18 recordsLinked to original sources
PubMed2005

Microlinguistic deficits in the narrative discourse of adults with traumatic brain injury.

BACKGROUND: Recent studies of microlinguistic impairments in the narrative discourse of adults with traumatic brain injury (TBI) have applied syntactic analyses, with some noting no deficits and others specific problems with sentence formulation. An alternative approach to examining the microlinguistic dysfunction in the discourse of individuals with TBI is through the use of propositional analysis. The advantage of propositional analysis is that it enables one to assess semantic complexity of utterances apart from sentence structure and grammaticality. AIMS: The present study applied propositional analysis to the story narratives of participants with TBI and participants with no brain injury (NBI). Specifically, the mean number of propositions within a sentence was tallied, in other words the participants' ability to insert multiple ideas into single surface sentences. It was hypothesized that the participants with TBI would produce fewer propositions per sentence because of organizational problems than the participants with NBI, regardless of level of education. METHODS AND PROCEDURES: Two story narratives (retelling and generation) previously elicited from the two participant groups (TBI (n = 53) and NBI (n = 42)) were analysed. For each language sample, the number of propositions was tallied and divided by the number of T-units. The resulting number, the propositional complexity index (PCI), was the average number of predicates per sentence. OUTCOMES AND RESULTS: Results indicated that the group with TBI produced significantly fewer propositions per T-unit. CONCLUSIONS: The present findings are in harmony with the notion that the participants with TBI studied presented with impairments of both micro- and macrolinguistic processes involved with the organization of semantic information in discourse. Clinical implications are discussed.

Adolescent↗
PubMed2004

Two-step reaction on a strained, nanoscale segmented surface.

By means of scanning tunneling microscopy and density functional theory calculations we demonstrate that on the Rh(110)-(10 x 2)-O surface, a prototypical multiphase surface of an oxidized transition metal model catalyst, water formation upon H2 exposure is a two-step reaction, with each step requiring special active sites. The 1st step initiates at (2 x 1)p2mg-O defect islands in the (10 x 2) structure and propagates across the surface as a reaction front, removing half of the adsorbed oxygen. The oxygen decorated Rh ridges of the (10 x 2) structure lose their tensile strain upon this reduction step, whereby nanoscale patches of clean Rh become exposed and act as special reaction sites in the 2nd reaction step, which therefore initiates homogeneously over the entire surface.

Journal Article↗
PubMed2001

Protein phosphorylation in mitochondria from human placenta.

The aim of this study was to investigate whether mitochondria from human placenta contain phosphorylated proteins and kinases. Interestingly, the placenta contains two types of mitochondria with different sizes. These are 'heavy' mitochondria which sediment at a much lower g force than 'light' mitochondria. Mitochondria were incubated with [gamma32]P-ATP and labelled proteins analysed by electrophoresis and autoradiography. A major protein band of 20 kDa was detected with minor bands at 22, 38 and 85 kDa. The 20 kDa band was attenuated by 83 per cent by the co-incubation of mitochondria with Herbimycin, a tyrosine kinase inhibitor. A 20 kDa protein was also identified using an anti-tyrosine phosphate antibody and detection of this protein was significantly higher in heavy mitochondria as opposed to light mitochondria. Protein kinase A enzyme activity was also detected in mitochondria at a level not significantly different than that found in whole non-fractionated cells. These data indicate that mitochondria from human placenta contains kinase activity and phosphoproteins. These molecules may have functions in signalling systems in this organelle. Phosphoprotein signalling systems may be differentially modulated in heavy mitochondria as compared with light mitochondria.

Adenosine Triphosphate↗
PubMed1999

Clinical and radiographic evaluation of early loaded free-standing dental implants with various coatings in beagle dogs.

STATEMENT OF PROBLEM: Immediate loading of implants may be a predictable treatment alternative when cross-arch stabilization with a fixed provisional is observed. PURPOSE: This study investigated the effect of immediate masticatory loading on the stability of single-standing dental implants with 4 different surfaces. MATERIAL AND METHODS: A total of 40 solid screw implants (diameter 3.3 mm, length 8 mm) were placed in the mandibles of 4 beagle dogs. Test groups included 3 hydroxyapatite (HA) coatings of titanium plasma-sprayed (TPS) implants. Implants with TPS alone served as control. Gold crowns were inserted 2 days after implant placement and the dogs were immediately put on a hard food diet. Implants were followed for 6 months after loading. Clinical and radiographic assessments of implants were performed at time of crown insertion (baseline) and after 1, 3, and 6 months of loading. The Periotest instrument was used for mobility measurements and radiographs were obtained for evaluation of peri-implant radiolucency and measurement of crestal bone changes. RESULTS: Of 40 implants, 39 displayed no discernible mobility, corresponding to successful clinical function. Peri-implant radiolucencies were absent for all but the 1 mobile implant. The reduction in crestal bone levels adjacent to the implants between baseline and 6 months was statistically significant (P <.0001). No statistically significant differences in crestal bone level changes over time were found between the various coatings demonstrating the absence of a treatment effect initiated by the surface coatings. CONCLUSION: In this study in beagle dogs, immediate masticatory loading of single-standing dental implants did not jeopardize tissue integration, provided the implants had excellent primary stability.

Analysis of Variance↗
PubMed1998

The effect of temperature changes on the dimensional stability of polyvinyl siloxane and polyether impression materials.

STATEMENT OF PROBLEM: Dental impressions are commonly mailed to remote dental laboratories and can be subjected to extreme temperature changes; however, the effects of these temperature changes on the accuracy of elastomeric impression materials are unknown. PURPOSE: This study evaluated the dimensional changes of polyether and polyvinyl siloxane impression materials as a function of storage temperature. MATERIAL AND METHODS: A total of 144 impressions were made of a stainless steel die similar to ADA Specification No. 19. Half of the impressions were made in perforated custom trays and the other half in solid trays. Measurements of the vertical and horizontal lines on the impressions were made at 10 minutes, 1 hour, 24 hours, and 26 hours, and storage temperatures ranged from 4 degrees C to 40 degrees C. RESULTS: Changes in storage temperature had a statistically significant effect on the dimensional stability of the horizontal and vertical lines. However, overall dimensional changes were extremely small. CONCLUSIONS: Storing both impression materials at 4 degrees C for 24 hours and then allowing the impressions to reach room temperature resulted in a slightly expanded impression that partially compensated for the contraction that occurred from polymerization shrinkage. Similar results occurred for polyether material only, when stored at 40 degrees C.

Analysis of Variance↗
PubMed1995

Bradykinin stimulates phospholipase D in PC12 cells by a mechanism which is independent of increases in intracellular Ca2+.

These experiments were designed to learn the role of bradykinin induced changes in intracellular Ca2+ in the activation of phospholipase D activity in PC12 cells. Ionomycin at a concentration of 0.1 microM caused an increase in intracellular Ca2+ comparable to bradykinin, but had no effect on phospholipase D activity. Carbachol, ATP, and thapsigargin also increased intracellular Ca2+ but had no effect on phospholipase D activity. Increases in intracellular Ca2+ may be a necessary but not a sufficient factor in the activation of phospholipase D. To investigate this issue, the bradykinin induced increase in intracellular Ca2+ was blocked by preincubating the cells in Ca(2+)-free media plus EGTA or in media containing the intracellular Ca2+ chelator BAPTA/AM. These preincubations completely blocked the bradykinin induced increase in intracellular Ca2+ but only attenuated the bradykinin mediated activation of phospholipase D. Physiological increases in intracellular Ca2+ apparently do not mediate the effect of bradykinin on phospholipase D.

Adenosine Triphosphate↗
PubMed1994

Reduced effectiveness of atrial natriuretic factor in pre-menopausal obese women.

It is well-known that the prevalence of hypertension progressively increases with body weight. Since the major physiological activities of atrial natriuretic factor (ANF) are its natriuretic, diuretic and vasodilatory effects, the aim of the present study was to investigate the ANF basal plasma levels and platelet receptor number in 15 young normotensive obese (O) and 12 age-matched normal weight healthy (C) women. ANF effectiveness was also studied in eight of the obese and seven of the control women, after an intravenous bolus of the hormone (human ANF (99-126): 0.5 mg/kg body weight). Results are expressed as means+s.d. Basal ANF plasma levels were similar between obese (18.2 +/- 9.7 pg/ml) and control women (12.3 +/- 7.7 pg/ml), whereas obese patients showed an increase density of platelet ANF-binding sites (clearance receptors) (C: 28.7 +/- 33.5 fmol/10(9) cells; O: 39.6 +/- 4.6 fmol/10(9) cells; P < 0.001), without apparent differences in receptor affinity (Kd) (C: 6.0 +/- 3.0 pM; O: 7.0 +/- 2.0 pM). The biological response to ANF, evaluated by changes of mean blood pressure levels (C: 5 +/- 1 mmHg; O: 1 +/- 1 mmHg; P < 0.001) and the percentage increase of diuresis (C: 159 +/- 52%; O: 81 +/- 62%; P < 0.01) and natriuresis (C: 205 +/- 129%; O: 99 +/- 41%; P < 0.05) was significantly reduced in obese patients. The percentage increase in sodium excretion was inversely related to the basal insulin concentrations in the obese group (r = 0.64, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

D-(-)-beta-hydroxybutyrate inhibits catecholamine-stimulated lipolysis and decreases beta-adrenoceptors' affinity in human fat cells but not in lymphomonocytes.

The effect of D-(-)-beta-hydroxybutyrate, at concentrations commonly achieved during ketoacidosis in humans (10 mmol/l), on human fat cell lipolysis in vitro was the aim of this study. The basal lipolysis was not modified and beta-hydroxybutyrate did not affect forskolin- or dibutyryl-cAMP-stimulated glycerol release, whereas it markedly inhibited isoproterenol-stimulated lipolysis. In membranes of intact adipocytes exposed to D-(-)-beta-hydroxybutyrate for 1 h, we found a decrease in beta-adrenoceptor affinity in saturation experiments and a shift to the right of the isoproterenol-mediated radioligand [( 125I]-cyanopindolol) displacement curve. These findings suggest that beta-hydroxybutyrate inhibits catecholamine-stimulated lipolysis by decreasing beta-adrenoceptor affinity. No effect of beta-hydroxybutyrate was found on beta-adrenoceptor binding of intact mononuclear cells of peripheral blood. In conclusion, the beta-adrenoceptor affinity lowering effect of beta-hydroxybutyrate is seemingly specific to human fat cells and might represent a feed-back mechanism that prevents an uncontrolled breakdown of triglycerides and indirectly regulates its own production rate.

3-Hydroxybutyric Acid↗
PubMed1990

Changes in overall plasma norepinephrine turnover and lymphomonocyte beta-adrenoceptor number during combined caloric and sodium restriction in normotensive obese subjects.

The aim of the study was to evaluate in eight normotensive obese patients the influence of low sodium intake (9 mEq/day) on the sympathetic activity modifications induced by caloric restriction (2511 kJ/day). As compared to the isocaloric salt balanced diet, 7 days of normosodic underfeeding induced a decrease in the overall norepinephrine turnover (clearance and appearance rate) and 24 hours urinary output, whereas the combined caloric and salt restriction significantly increased the norepinephrine appearance rate and even more the norepinephrine clearance but, on the other hand, decreased the beta-adrenergic receptor number on the lymphomonocyte surface, suggesting a reduced peripheral sensitivity to catecholamines. Therefore, the utility of the combined sodium and caloric restriction in the treatment of the normotensive obese patients remains still questionable.

Adolescent↗
PubMed1989

Influence of lactate on isoproterenol-induced lipolysis and beta-adrenoceptors distribution in human fat cells.

The influence of lactate on human adipocytes lipolysis and the possible relationship between lactate-induced metabolic effects and beta-adrenoceptor binding sites were investigated. beta-sites were identified in membranes with (125I)-cyanopindolol and in intact cells with (125I)-cyanopindolol and (3H)-CGP 12177. Lactate reduced isoproterenol-induced lipolysis in a dose-response fashion and such inhibition became significant only at 16 mmol/l lactate. Exposure of human fat cells to 16 mmol/l lactate significantly reduced beta-adrenoceptors density on crude membranes. When the binding assay was performed on intact cells using (125I)-cyanopindolol at 37 degrees C, the radioligand identified the same number of receptors, regardless of the presence of lactate in the preincubation medium. When (3H)-CGP 12177 was used, it bound to about 35% less receptors in lactate pre-treated cells than in control. Seemingly, at 37 degrees C, because of its lipophilicity, (125I)-cyanopindolol can cross the plasma membrane and bind to intracellular sites whereas, (3H)-CGP 1277, due to its hydrophilicity, identifies surface receptors only. Thus, the present in vitro study provides evidence that high levels of lactate, similar to the concentrations usually achieved in overt lactic acidosis, are able per se to inhibit human lipolysis and to redistribute beta-adrenoceptors from cell surface to a domain not accessible to hydrophilic ligands.

Adipose Tissue↗
PubMed1989

Biophysical and endocrine-metabolic changes during menopausal hot flashes: increase in plasma free fatty acid and norepinephrine levels.

Thermocutaneous, vascular, metabolic and hormonal changes were investigated during 11 hot flashes from 6 postmenopausal women. The first detectable change was an increase in finger blood flow with a concomitant enhancement of skin conductance. The increase in skin conductance was followed rapidly by a sharp rise in finger temperature. The main endocrine-metabolic changes associated with the above phenomena were a sharp increase in plasma free fatty acids (approximately 65%), norepinephrine (approximately 100%) and LH (approximately 20%) levels. Plasma glucose and cortisol tended to be increased but did not reach statistical significance; on the other hand, plasma insulin, glucagon, growth hormone, epinephrine and dopamine remained unchanged.

Adult↗
PubMed1986

Arginine-vasopressin response to supine-erect posture change: an index for evaluation of the integrity of the afferent component of baroregulatory system in diabetic neuropathy.

The arginine-vasopressin (AVP) response to supine-standing postural change was evaluated in eight healthy subjects and in fourteen diabetic patients. Plasma AVP levels were found to increase in the controls and in nine subjects from the diabetic group. In the controls the increase was 139% 5 min. after standing and 275% 120 min. after standing. In four of the diabetics affected by autonomic neuropathy AVP failed to increase in response to standing, thus suggesting lesions of the neurogenic pathways connecting baroreceptors to neurohypophysis. Consequently, a failure of the afferent limb in the baroregulatory system must be taken into account among other localizations of autonomic neuropathy. On this basis, AVP measurement both in supine and erect positions could represent an additional test for assessing the integrity of the autonomic nervous system.

Adolescent↗
PubMed1984

[Determination of glycemia with a new reflex photometer (glucometer)].

The introduction on the market of small sized (easy to use) reflectance photometers for determination of blood glucose levels offers a new possibility in the monitoring homeostasis of glucose in diabetic patients. An evaluation of the system has been performed comparing the results with those obtained by spectrophotometer methods. Results by the two methods are quite comparable. A wide use of this system for blood monitoring should be encouraged especially among the diabetic patients in order to allow them to achieve a higher autonomy, particularly in emergency situations.

Blood Glucose↗
PubMedDate not supplied

[The nucleolus organizer region in benign and malignant melanocyte lesions of the skin: a quantitative study].

By means of a silver staining method, Nucleolar Organizer Region-associated proteins (NORs) have been evaluated on paraffin sections of two series of benign and malignant melanocytic skin lesions (represented by 30 intradermal naevi and 30 malignant melanomas). A significant difference (P less than 0.001) was found between the numbers of Ag-NORs in the nuclei of benign lesions and those of malignant lesions. It is suggested that this method could be of value in assessing the biological potential of cutaneous melanocytic neoplasms.

Adult↗