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Biomedical subjects

L Monti

Publications and source records attributed to L Monti.

At least 37 records · Page 2Linked to original sources
PubMed1999

Delayed recognition memory in Parkinson's disease: a role for working memory?

Immediate and delayed recognition memory for words was examined in a sample of 16 non-demented patients with Parkinson's disease and 16 normal control participants of equivalent age and educational attainment. The patients, relative to control participants, had intact immediate but impaired delayed recognition memory performance. Patients were also impaired on tests of free and cued recall, working memory and a measure of psychomotor processing speed. Processing speed was a significant covariate for delayed recognition, free and cued recall and working memory performance, but not for immediate recognition performance. These results suggest that the same cognitive processes which support performance on tests of recall and working memory also support performance on tests of delayed recognition.

Aged↗
PubMed1999

Methods for quantitative analysis of the primary stability in uncemented hip prostheses.

Torsional loads of daily activities contribute to the failure of the primary fixation of hip prostheses. Implant torsional stability must be evaluated prior to in vivo clinical trials. Whereas previous work has investigated this phenomenon, descriptions of physiologically accurate and reproducible in vitro methodologies are rare. The present study aimed to detect and control the sources of error and variability that influence in vitro methods. A typical set-up for the analysis of primary stability of hip stems was studied. Load cycles included proximal-to-distal axial force, torque, and bending moment. The effects of loading frequency and strain distribution across the cortical bone were investigated in order to optimize testing conditions and measurement set-up. The relative shear motion at the bone-stem interface was measured transcortically using linear variable displacement transducers. The procedures developed for mounting specimens on the testing machine and for positioning sensors on the specimen were standardized and tested for reproducibility. The protocol was finally tested for repeatability and accuracy. Measurement errors were 2.3 microm between load cycles and 4.9 microm for repeated set-ups, comparing favorably with the literature.

Activities of Daily Living↗
PubMed1999

Human immunodeficiency virus infection, inducible nitric oxide synthase expression, and microglial activation: pathogenetic relationship to the acquired immunodeficiency syndrome dementia complex.

The regional expression of immune-mediated and neurotoxic events in the human immunodeficiency virus (HIV)-infected brain in relationship to the acquired immunodeficiency syndrome (AIDS) dementia complex (ADC) and brain pathology remains uncertain. The extent of gp41, inducible nitric oxide synthase (iNOS), and HLA-DR expression was examined in the frontal lobe and basal ganglia of 25 patients at varying stages of ADC. The expression of gp41 and iNOS was present predominantly in perivascular cells and most often in the basal ganglia. Staining for gp41 correlated significantly with iNOS in the basal ganglia, whereas the severity of staining for gp41 and iNOS in the basal ganglia and white matter was significantly greater in subjects with moderate to severe dementia compared with those with milder impairment. The degree of macrophage staining in the white matter and basal ganglia also correlated significantly with ADC severity and was more abundant than gp41 or iNOS staining, particularly in the white matter. Logistic regression analysis revealed that staining for iNOS and gp41 increased linearly with ADC severity and was significantly more abundant in the basal ganglia compared with the white matter. Double-immunolabeling studies colocalized iNOS predominantly to macrophage/microglia and to gp41-positive cells. The expression of iNOS and gp41 in the basal ganglia combined with immune activation contributes to the development and progression of the clinical syndrome.

AIDS Dementia Complex↗
PubMed1998

Recent advances in antihypertensive therapy.

There are multiple different approaches that have been adopted in the past to cure hypertension. Hypertension is a multifactorial disease frequently associated with other cardiovascular problems. None of the antihypertensive drugs available can cure all cases of hypertension. This situation causes a unique scenario in this area of therapeutic research: less recent approaches, which make use of drugs acting on the adrenergic system, diuretics, calcium antagonists, nitro-vasodilators and so on, have not yet been abandoned, while new compounds are still being developed today. Newly acquired and more detailed knowledge of the renin-angiotensin system, of the role of the endothelium and ionic channels in the homeostasis of blood pressure has opened up new lines of study. There are also a number of experimental compounds targeted for other action mechanisms (phosphodiesterase inhibitors, neuropeptide Y antagonists, ouabain-like factor antagonists), that could also represent innovative approaches to hypertension therapy. Some hints regarding the current developments in the well established and innovative categories of antihypertensives will be given in this review.

Animals↗
PubMed1997

Migration of metallic clips used during laparoscopic cholecystectomy and formation of gallstones around them: surgical implications from a prospective study.

Two groups of patients, with laparoscopic cholecystectomy (LC) were prospectively studied. All patients had serial plain abdominal X-ray examinations at various intervals after operation, to record the position of clips placed during LC. Seventy-one patients had less cystic duct (CD) dissection and > or =4 clips placed during the procedure. One hundred and fifteen patients had a larger CD dissection and only 4 clips placed (2 on the cystic artery and 2 on the CD, without additional clips on smaller vessels). In the former group, 7 patients had clip migration within 1 month and 11 within 1 year vs 1 either at 1 month or 1 year in the latter group (p = 0.01 and <0.001, respectively). During the follow-up, a 72-year-old man belonging to the former group had a recurrent common duct brown pigment stone containing a metallic clip 26 months after operation. He was treated successfully by endoscopic sphincterotomy. Factors predisposing to clip migration were short cystic stump, inadvertent clip dislodgment or incorrect placement, cystic duct ischemic necrosis, and local suppurative complications. Data from 29 patients with GS formed around suture material or phytobezoars observed during a prospective study and from the physicochemical and structural analysis of a cumulative series of 64 GS containing foreign bodies are also presented and discussed. It is suggested that metallic clips can migrate from their initial sites at various intervals within the peritoneal cavity or into the common duct and serve as a nidus for GS formation. Metallic clip migration in most cases is due to technical factors and can usually be prevented. However, it is not possible to prevent either clip migration or GS formation in every case, since even well-placed clips can migrate due to suppurative complications or local ischemic damage, and, once that penetration within the bile tract has occurred, GS are usually going to form, irrespective of the nature and the shape of the foreign body.

Adolescent↗
PubMed1996

Case report: sequential bilateral carotid dissection leading to Raeder's syndrome.

A 39-year-old man complained of unilateral headache, diplopia and marked anterior neck oppression "like a necklace". MRA was used to study this case of subsequent bilateral internal artery dissection (ICAD) which initially appeared as Raeder's syndrome. MRA proved to be a non-invasive alternative for studying stenosis, occlusions and dissections of the intracranial and extracranial vessels.

Adult↗
PubMed1994

Iomeprol versus iopamidol in contrast-enhanced computed tomography of thoracic and abdominal organs.

The aim of this double-blind, parallel-group study was to compare the safety, tolerance, and efficacy of iomeprol-350 (350 mgI/ml), iomeprol-400 (400 mgI/ml) and iopamidol-370 (370 mgI/ml) for use in contrast-enhanced body computed tomography (CT). Following written informed consent, 120 adult inpatients of either sex requiring CT of thoracic or abdominal organs were randomly assigned to receive iomeprol-350, iomeprol-400 or iopamidol-370. Pre- and post-contrast, all patients underwent clinical, instrumental and laboratory investigation to assess the safety of the test agents. Tolerance was assessed in terms of discomfort associated with contrast injection. Two experienced radiologists independently and blindly graded the quality of contrast enhancement obtained with the different contrast solutions by means of a five-point ordinal scale as follows: 1, insufficient; 2, sufficient; 3, good; 4, excellent; or E, excessive. Patients in the iomeprol groups needed fewer injections and a smaller volume of contrast medium to obtain examinations of adequate diagnostic quality. Contrast enhancement was judged as excellent or good in about 90% of the study examinations, without significant differences between the three study groups. During contrast injection, heat and pain sensations were minimal or absent in most cases. No serious adverse events occurred throughout the study. No significant changes in clinical, instrumental or laboratory safety parameters were observed. In conclusion, iomeprol-400 and iomeprol-350 appear to be contrast solutions at least as safe, well tolerated and effective as iopamidol-370 when used as contrast agents for body CT.

Adult↗
PubMed1993

Assessment of proinsulin's effects on intermediary metabolism using the forearm technique in normal man.

We have compared the effects of human proinsulin and insulin on forearm metabolism. Seven normal, non-obese subjects were infused with 386 pmol/kg per hour of proinsulin and 180 pmol/kg per hour of insulin using the euglycaemic clamp technique. Glucose appearance and utilization rates were quantified using a primed continuous infusion of [6',6'-2H2]glucose. Mean blood glucose was 4.1 +/- 0.1 and 4.1 +/- 0.2 mmol/l during proinsulin and insulin infusions respectively. Basal insulin concentrations increased from 0.02 +/- 0.01 to 0.25 +/- 0.03 nmol/l. The proinsulin infusion was chosen to give steady-state levels approximately 20-fold higher on a molar basis than those of insulin, based on previous findings that proinsulin has only 5% the biological potency of insulin. Basal proinsulin concentrations increased from 0.003 to 5.4 +/- 0.3 nmol/l. Hepatic glucose production was suppressed similarly during the last hour of each hormone infusion: 0.07 +/- 0.16 (proinsulin, P), and 0.01 +/- 0.13 (insulin, I) mg/kg per minute. Glucose disposal, however, was significantly increased during the final hour of the insulin infusion: 4.7 +/- 0.4 (I) and 3.4 +/- 0.2 (P) mg/kg per minute (P = 0.025). Net forearm glucose uptake (FGU) increased by a greater amount during insulin compared with proinsulin infusion: 1.44 +/- 0.02 (I) and 0.71 +/- 0.01 (P) mumol/100 ml forearm per minute (P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Proinsulin and insulin concentrations following intravenous glucose challenges in normal, obese, and non-insulin-dependent diabetic subjects.

We investigated the effects of different intravenous (IV) glucose challenges on insulin and proinsulin secretion. On separate occasions, seven normal controls and five obese and five non-insulin-dependent diabetic (NIDDM) subjects each received an IV glucose tolerance test (IVGTT), a hyperglycemic clamp (HY), and a 60-minute, standardized, low-dose, continuous infusion of glucose (CIG) in a randomized fashion. Basal proinsulin concentrations in NIDDM subjects (8.4 +/- 5.0 pmol/L) were significantly higher compared with those of normal (1.1 +/- 0.2) and obese subjects (1.5 +/- 0.4; both P < .05). Basal molar proinsulin:insulin ratio (P:I) was also significantly higher in NIDDM subjects (22% +/- 12%) compared with normal (1.0%) and obese subjects (1.6% +/- 0.8%; both P < .01). Proinsulin concentrations did not increase significantly in any group during the first 10 minutes of the IV glucose challenges. However, during HY, significant increases in proinsulin concentration occurred after 60 minutes in each group. In normal and obese subjects, IV glucose administration resulted in significant acute increases in insulin concentrations compared with the characteristic blunted response in NIDDM subjects. The P:I ratio in normal and obese subjects did not change in the first 10 minutes after IV glucose administration. However, by the end of HY, the P:I ratio had increased significantly in normal subjects by 1% to 5% +/- 2% (P < .05), and in obese subjects by 1% to 5% +/- 1% (P < .02). In NIDDM subjects, both HY (19% +/- 10% to 27% +/- 12%) and IVGTT (18% +/- 9% to 43% +/- 16%) resulted in a transient increase in the basal P:I ratio by 5 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

The effects of subcutaneous human proinsulin on the production of 64/65 split proinsulin, glucose turnover and intermediary metabolism in non-insulin-dependent diabetic man.

We have compared the effects of subcutaneously injected human proinsulin, insulin zinc suspension and inactive diluent (control) on glucose turnover, intermediary carbohydrate and lipid metabolism in non-insulin-dependent diabetic man. Six weight-matched (24.8 +/- 1.6 kg M-2) non-insulin-dependent diabetic subjects underwent 3 separate, randomized, 10 h isoglycemic clamps. Glucose turnover was measured using a primed continuous infusion of [6'6'2H2] glucose. Each subject received 0.35 U/kg of hormone or control made up to isovolumetric amounts. The mean blood glucose level of 7.3 +/- 0.8 mmol/l was similar at the start of each isoglycemic clamp. Incremental area under the curve proinsulin levels (1195 +/- 146 nmol/l) were about 21-fold higher, on a molar basis, than insulin (62.4 +/- 10 nmol/l). Des 64/65 split proinsulin increased in a parallel manner to intact proinsulin (r = 0.99, P < 0.0001) and comprised approximately 13% of the intact proinsulin concentration. Hepatic glucose production was suppressed similarly following proinsulin and insulin zinc injection. However, both proinsulin and insulin zinc had a significantly greater effect on suppression of hepatic glucose production compared to control (P = 0.01, P = 0.009, respectively). Metabolic clearance rate of glucose fell significantly during the control studies compared to insulin zinc or proinsulin injections (P < 0.05). Blood lactate, pyruvate and alanine concentrations were similar following control or hormone injections. However blood glycerol, 3-hydroxybutyrate and plasma-non-esterified fatty acids were suppressed significantly by proinsulin and insulin zinc compared to control injections. The conclusions were: (1) In overnight fasted hyperglycemic non-insulin-dependent subjects s.c. injections of proinsulin and insulin zinc can produce similar effects on glucose turnover, intermediary lipid and carbohydrate metabolism. (2) Similar carbohydrate intermediary metabolism profiles can be obtained following insulin zinc, proinsulin or control injections. (3) However lipolysis and ketogenesis were significantly suppressed by both hormones compared to control. (4) Subcutaneous proinsulin injection resulted in approximately 13% conversion to des 64/65 split proinsulin.

Alanine↗
PubMed1993

Estimates of insulin action in normal, obese and NIDDM man: comparison of insulin and glucose infusion test, CIGMA, minimal model and glucose clamp techniques.

Many methods of varying complexity are available for the measurement of insulin resistance (action) in man. No study has previously compared several of these in the same subjects to establish which is the most appropriate for routine use. We have, therefore, compared six methods: the hyperinsulinemic eu(iso)-glycaemic clamp (Eu), insulin glucose infusion test (IGI), hyperglycaemic clamp (Hy), continuous infusion of glucose with model assessment (CIGMA), minimal model (Min) and modified minimal model (Mod). Nineteen subjects with varying degrees of glucose tolerance were studied. Eight normal (BMI 22.5 +/- 1.5 kg/m2), six obese (BMI 38 +/- 5 kg/m2) and five NIDDM subjects (BMI 27 +/- 3 kg/m2) were investigated, in a randomized fashion, on separate days. The ratio of metabolic clearance rate of glucose (MCRG) and Insulin (I) was used as the measure of insulin action during Eu, Hy and IGI. Si was calculated as the index of insulin sensitivity from (Min) and (Mod) and CIGMA was obtained as previously described. MCRG was converted to Si to allow for direct comparison with (Min). Methods requiring incremental endogenous insulin secretion (which was highly variable) to calculate an index of insulin action (Si Min, Si Hy and CIGMA) failed to find an overall difference between groups. Only Si Eu (p = 0.007) and Si IGI (p = 0.001) demonstrated a significant overall group difference when Si was used. When MCRG/I was used, Eu, IGI and Hy were able to distinguish a significant overall group difference. With the exception of CIGMA and SiHy all other methods found a significant difference in insulin action between normals and NIDDM subjects. Only Eu and IGI could distinguish obese from normal, while only Si Min, could distinguish obese from NIDDM subjects. Eu and IGI were the only methods to be significantly correlated: normals Rs = 0.75, p < 0.05, obese Rs = 0.9, p < 0.05, and NIDDM Rs = 1.0, p < 0.05. In conclusion we have demonstrated that: 1) The insulin-glucose infusion test and the eu(iso)glycaemic clamp were significantly correlated in normals, obese and NIDDM subjects. 2) Only the eu(iso)glycaemic clamp and insulin glucose infusion test could significantly separate obese from normal subjects. 3) the IGI appears to be a practical, simple and precise method for measuring in vivo insulin action in man and gives results closely similar to those found with the hyperinsulinemic eu(iso)glycaemic clamp.

Adult↗
PubMed1992

Determination of plasma [6,6-2H2]glucose enrichment by a simple and accurate gas chromatographic-mass spectrometric method.

An improved method for the evaluation of glucose turnover rate in humans, using a prime-continuous infusion of [6,6-2H2]glucose, was developed. Deproteinization of plasma and conversion of glucose into the aldononitrile pentaacetate derivative are the only sample manipulations required prior to the gas chromatographic-mass spectrometric analysis. In six normal adults (prime = 5 mg kg-1; continuous infusion = 0.05 mg kg-1 min-1) the hepatic glucose output calculated at steady state by the procedure described here was 2.1 +/- 0.2 mg kg-1 min-1, the isotopic enrichment being determined with a coefficient of variation of ca. 2%. In six additional subjects, with half of the above-mentioned doses of labelled glucose, the mean hepatic glucose output was exactly the same (3.2% coefficient of variation for the isotopic enrichment measurement). The method described allows the hepatic glucose output to be precisely determined with savings both of time and of labelled glucose.

Blood Glucose↗
PubMed1992

Dose-response characteristics of human proinsulin and insulin in non-insulin-dependent diabetic humans.

We compared the actions of human proinsulin and insulin on glucose turnover and on intermediary carbohydrate and lipid metabolism in non-insulin-dependent diabetes mellitus (NIDDM). Six diet-controlled weight-matched (25.4 +/- 1.0 kg/m2) NIDDM subjects underwent six separate isoglycemic clamps. Glucose turnover was measured using a primed continuous infusion of [6',6'-2H2]glucose. Each subject received three low-dose intravenous infusions of both insulin and proinsulin. Blood glucose was maintained at 6.7 +/- 0.3 mM during proinsulin and insulin infusion. Insulin (I) infusions gave steady-state levels of 0.12 +/- 0.001 (I1), 0.18 +/- 0.01 (I2), and 0.33 +/- 0.01 nM (I3). Steady-state proinsulin (P) levels were 2.5 +/- 0.1 (P1), 4.3 +/- 0.2 (P2), and 8.8 +/- 0.9 nM (P3). Hepatic glucose production was suppressed equally by proinsulin and insulin at all doses. The metabolic clearance rate of glucose was significantly increased during the insulin infusion compared with proinsulin. The use of [6',6'-2H2]glucose resulted in a mean underestimation of the glucose infusion rate of 10.0 +/- 4.0 and 6.0 +/- 2.5% during the two highest insulin and proinsulin doses, respectively. Proinsulin had a significantly weaker effect than insulin, at the lowest infusion dose, in percent suppression of plasma nonesterified fatty acids, blood glycerol, and beta-hydroxybutyrate levels (all P less than 0.05). Blood lactate levels were lower during the P1 (628 +/- 43 microM) and P2 (657 +/- 93 microM) infusions compared with I1 (776 +/- 60 microM) and I2 (878 +/- 44 microM; P less than 0.05, P less than 0.02), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Diabetes Mellitus, Type 2↗
PubMed1992

A comparison of four methods for assessing in vivo beta-cell function in normal, obese and non-insulin-dependent diabetic man.

Several methods of varying complexity are available for the measurement of in vivo insulin secretion in man. No study has previously compared these in the same subjects to establish which is the most appropriate for routine use. We have, therefore, compared four methods for measuring insulin secretion in man: Hyperglycaemic clamp (Hy), Minimal model (MIN), shortened intravenous glucose tolerance test (IVGTT) and continuous infusion of glucose with model assessment (C.I.G.M.A.). Seventeen subjects with varying degrees of insulin sensitivity were studied. Seven normal (BMI 22.5 +/- 1.5 kg/m2), five obese (BMI 38 +/- 5 kg/m2) and five NIDDM subjects (BMI 27 +/- 3 kg/m2) were investigated, in a randomised fashion, on separate days. First (PSI) and second phase (PSII) rate constants (MIN); incremental insulin secretion 0-10 mins (Hy delta I) and steady state insulin levels from the last 30 minutes (Hy120-150) from the hyperglycaemic clamp; 3 minute insulin concentration and incremental area under insulin secretion curve 0-10 min (IVGTT) and beta-cell function (%) from C.I.G.M.A. were used as indicators of insulin secretion. Each index of insulin secretion could detect an overall difference between the groups. Insulin secretion in normals and obese was similar but significantly increased compared to NIDDM. In normals PSI correlated with C.I.G.M.A. (Rs = 0.92, p < 0.02) and Hy120-150 (Rs = 0.82, p < 0.05). IVGTT0-10 correlated with PSII (Rs = 0.83, p < 0.05), HY delta I (Rs = 0.84, p < 0.05) and IVGTT3 min (Rs = 1.0, p < 0.001). In obese PSII correlated with C.I.G.M.A. (Rs = 0.91, p < 0.05), Hy delta I (Rs = 1.0, p < 0.02) Hy120-150 (Rs = 0.92, p < 0.05) and IVGTT3 min Rs = 1.0, p < 0.02). In addition Hy delta I also correlated with C.I.G.M.A. (Rs = 0.92, p < 0.05) and IVGTT3 min (Rs = 1.0, p < 0.02). In NIDDM Hy delta I correlated with C.I.G.M.A. (Rs = 0.91, p < 0.005). When all subjects from the three groups were combined, significant positive correlations were obtained between each index of insulin secretion. In conclusion we have demonstrated that: (a) C.I.G.M.A., IVGTT, Minimal model and hyperglycaemic clamp can provide similar overall results for, in vivo, beta-cell function in man. (b) Significant positive correlations were obtained between each index of insulin secretion when all subjects were combined. (c) Using the above methodologies insulin secretion in normal and obese appears similar but significantly increased compared to NIDDM subjects.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1992

[Significance of the combination of small intestine enema and ultrasonography in the follow-up of Crohn's disease. Clinical correlations].

High-resolution US yields important information for the study of Crohn's disease. A more accurate follow-up is possible by the integration of US with radiological and clinical findings. Sixty-two patients with suspected or known Crohn's disease were examined with double-contrast small bowel enema and high-resolution US. The latter allowed the demonstration of such pathologic findings as mesenteric thickness greater than 15 mm, submucosal thickness (third hyperechoic layer greater than 50% of total bowel wall thickness), lymphadenopathies, and fluid collections. The authors suggest that US grading be performed, and radiological correlations made. The combined use of the two techniques yields better results and allows a better assessment of the patients, which is very useful for both prognosis and therapy.

Adolescent↗
PubMed1991

[Integrated imaging of hepatocarcinoma. Personal experience].

Hepatocellular carcinoma (HCC) is the commonest primary tumor of the liver; of late, its incidence has increased in the Western world. The authors report their experience with 42 patients affected with HCC; 36 cases were confirmed by fine-needle biopsy (FNAB), and 2 by surgery. All patients were studied with US and CT; 25 of them underwent color-Doppler US, and 30 angiography. In 9 patients, Lipiodol-CT was performed after hepatic arterial chemo-embolization. Thirty-six expansive and expansive-infiltrative lesions were observed, 4 infiltrative ones, and 1 neoplastic thrombosis of the portal vein with no evidence of parenchymal mass; 28 cases were multinodular in nature. US showed the primary lesion in all cases, while CT missed 2 lesions of 15 mm in diameter. In 19 of 25 cases studied with color-Doppler US, arterial pathologic signals were observed. Angiography confirmed all the primary lesions diagnosed by US in 30 patients and was found to be the most sensitive method to reveal multinodular lesions 8-15 mm phi, whereas Lipiodol-CT had higher resolution in detecting nodules up to 3 mm phi. The retrospective review of our results pointed out the capabilities of diagnostic imaging techniques in characterizing and staging HCCs--which is the reason why the role of biopsy has not been emphasized. The whole of the morphofunctional data obtained with the different techniques allowed lesion tissue characterization.

Adolescent↗