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Biomedical subjects

G Martini

Publications and source records attributed to G Martini.

At least 55 records · Page 3Linked to original sources
PubMed1998

Stability of water-soluble and lipid-soluble paramagnetic probes in Bacillus subtilis.

Batch cultures of the Gram-positive bacterium Bacillus subtilis PB19 have been investigated for their metabolic action to electron spin resonance (ESR) probes. Five- and six-membered water-soluble and lipid-soluble nitroxides have been used, which were reduced most probably to the corresponding hydroxylamine derivatives. The reduction was followed by the ESR signal intensity and found to be dependent on chemical structure and stability, lipophilic/hydrophilic character, charge, concentration, and temperature. Water-soluble nitroxides did not show apparent toxicity towards B. subtilis, in contrast with n-DXSA (n=5, 12, 16) which were found to be strongly cytotoxic. The cytotoxicity depended on the position of the doxyl unit along the hydrocarbon chain. The hydrophilic nitroxides were reduced at a much slower rate relative to the lipophilic ones. Membrane diffusion was suggested to be a slower process relative to chemical reduction for water-soluble nitroxides. The lipophilic nitroxides were solubilized into the membrane where they were rapidly reduced with a reduction maximum at 303-310 K, which is the optimal growth temperature of B. subtilis, while an inactivation at higher temperatures was observed. Both toxicity and reduction rates of nitroxides strongly indicated that the reduction was an enzyme-mediated process taking place near the outer surface of the periplasmic membrane.

Bacillus subtilis↗
PubMed1998

Modified "T" stenting: a technique for kissing stents in bifurcational coronary lesion.

The kissing stenting using a new technique in two patients is reported. A stent was positioned at the ostium of the side branch. Another stent was advanced into the main vessel until the center of the stent was positioned near the origin of the side branch. The stent at the ostium of the side branch was deployed and the balloon and the guidewire were removed from the side branch. Thereafter, the stent in the main vessel was deployed. The follow-up angiogram of those patients showed no restenosis in both the vessels.

Aged↗
PubMed1998

Secondary osteoporosis.

Generalized osteoporosis currently represents a heterogeneous group of conditions with many different causes and pathogenetic mechanisms, that often are variably associated. The term "secondary" is applied to all patients with osteoporosis in whom the identifiable causal factors are other than menopause and aging. In this heterogeneous group of conditions, produced by many different pathogenetic mechanisms, a negative bone balance may be variably associated with low, normal or increased bone remodeling states. A consistent group of secondary osteoporosis is related to endocrinological or iatrogenic causes. Exogenous hypercortisolism may be considered an important risk factor for secondary osteoporosis in the community, and probably glucocorticoid-induced osteoporosis is the most common type of secondary osteoporosis. Supraphysiological doses of corticosteroids cause two abnormalities in bone metabolism: a relative increase in bone resorption, and a relative reduction in bone formation. Bone loss, mostly of trabecular bone, with its resultant fractures is the most incapacitating consequence of osteoporosis. The estimated incidence of fractures in patients prescribed corticosteroid is 30% to 50%. Osteoporosis is considered one of the potentially serious side effects of heparin therapy. The occurrence of heparin-induced osteoporosis appeared to be strictly related to the length of treatment (over 4-5 months), and the dosage (15,000 U or more daily), but the pathogenesis is poorly understood. It has been suggested that heparin could cause an increase in bone resorption by increasing the number of differentiated osteoclasts, and by enhancing the activity of individual osteoclasts. Hyperthyroidism is frequently associated with loss of trabecular and cortical bone; the enhanced bone turnover that develops in thyrotoxicosis is characterized by an increase in the number of osteoclasts and resorption sites, and an increase in the ratio of resorptive to formative bone surfaces, with the net result of bone loss. Despite these findings, the occurrence of pathological fractures in patients with hyperthyroidism is relatively low, and probably due to the fact that deficiencies in bone mass may be reversed by treatment of the thyroid disease. Most, but not all, studies on insulin-dependent diabetes mellitus (IDDM) report an association with osteopenia. In IDDM, the extent of bone loss is usually slight, which helps explain the discrepancy between the frequency of decreased bone mineral density, and the frequency of osteoporotic fractures in long-standing diabetes. Contradictory results have been obtained in non-insulin-dependent diabetes mellitus (NIDDM) patients. Increased rates of bone loss at the radius and lumbar spine were demonstrated either in patients with two-thirds gastric resection and Billroth II reconstruction, or in those with one-third resection and Billroth I anastomosis, and the metabolic bone disease following gastrectomy may consist also of osteomalacia or mixed pattern of osteoporosis-osteomalacia, with secondary hyperparathyroidism. Miscellaneous causes of secondary osteoporosis are also immobilization, pregnancy and lactation, and alcohol abuse.

Adult↗
PubMed1998

Blood pressure and heart rate in young thalassemia major patients.

The analysis of blood pressure (BP) and heart rate (HR) variability is currently used to investigate the mechanisms responsible for cardiovascular control; therefore, we assessed whether an impairment of 24-h BP and HR profiles and sympathovagal interaction modulating cardiovascular function was present in patients with thalassemia major (TM) in preclinical phase of heart disease. Nine beta-thalassemic patients 18 years old without clinical signs of cardiac failure and 9 age- and sex-matched controls were studied. Twenty-four-hour-ambulatory BP and HR were measured using the SpaceLabs 90207 device. A truncated Fourier series with four harmonics was used to describe the diurnal blood pressure profile. Mean 24-h ambulatory systolic BP, diastolic BP, and mean arterial pressure were significantly lower in TM patients than in normal subjects (P < .05). A significantly higher nighttime HR value was found in TM patients (P < .05). More than 40% of the TM patients did not show a significant diurnal BP and HR rhythm. In TM patients, the overall amplitude of systolic BP, diastolic BP, and HR was significantly lower than in controls (P < .01). The night/day differences of systolic BP, diastolic BP, and HR were significantly lower in TM patients than in normals (P < .01). Furthermore, we performed power spectral analysis on short-term continuous finger BP and HR data in supine position and during passive head-up tilt. Total spectral power of systolic BP was significantly lower in patients than controls (P < .05). Low-frequency (LF) power of systolic BP and diastolic BP and LF/high-frequency (HF) ratio of HR were significantly lower during tilt in TM patients compared to controls (P < .05). High-frequency power of HR was significantly higher in patients than controls (P < .05). The baroreflex gain assessed by alpha-index was the same in supine position but was higher in TM patients during passive tilt (P < .05). An inverse relationship between LF/HF ratio of HR and hemoglobin levels in TM patients was found. Finally, plasma norepinephrine levels were significantly lower in thalassemics (P < .005). In young TM patients in a preclinical stage of heart disease, these findings demonstrated abnormal 24-h BP and HR rhythms and a decreased short-term variability of BP and HR, in particular in the LF range, showing a diminished sympathetic activity.

Adolescent↗
PubMed1998

Noninvasive assessment of spontaneous baroreflex sensitivity in patients with liver cirrhosis.

AIMS/BACKGROUND: An impairment of baroreceptor sensitivity has been found in liver cirrhosis. Noninvasive and spontaneous estimates of baroreflex sensitivity are obtained from beat-to-beat blood pressure and heart rate recordings by means of cross-spectrum analysis and calculation of alpha-index (as a measure of baroreflex gain). The aim of the present study was to investigate the function of the spontaneous baroreflex sensitivity related to clinical Child score in liver cirrhosis. METHODS: The alpha-index was evaluated in 40 cirrhotic patients (18 with and 22 without ascites) and 17 healthy subjects by analysing finger arterial pressure recorded noninvasively with the Portapres device. RESULTS: Baroreflex sensitivity was significantly lower in cirrhotic patients with and without ascites compared with healthy subjects (p<0.01). Furthermore, in patients with ascites the baroreflex gain was significantly related to plasma sodium (p<0.01). A significant inverse relationship was present between baroreflex gain and grade of Child score and the severity of ascites (p<0.01). There were no significant relationships between hormonal parameters (catecholamines, renin, aldosterone, arginine-vasopressin, atrial natriuretic peptide and nitric oxide) and baroreflex gain. No significant differences were found between healthy subjects and cirrhotic patients with respect to systolic and diastolic blood pressure total variability in a supine position, whilst it was lower in cirrhotic patients with ascites in a tilted position (p<0.05). CONCLUSION: Our findings showed that baroreflex sensitivity was significantly impaired in cirrhotic patients when compared with healthy subjects. In addition, there was a significant trend toward lower baroreflex sensitivity values with the grade score of Child class (p<0.01). Spectral analysis of the alpha-index provides viable alternatives to the pharmacological approach for estimation of baroreflex sensitivity and may represent a prognostic tool to identify cirrhotic patients at increased risk of adverse events.

Aldosterone↗
PubMed1998

Central diabetes insipidus with spontaneous remission. A case report.

We report a case of central diabetes insipidus with spontaneous remission 8 months after clinical beginning of the disease. A 20 years-old man developed polydipsia and polyuria in October 1994. A water deprivation study showed a defect in the urine concentrating function, which was corrected by vasopressine. A Magnetic Resonance imaging of the skull revealed a thickening of the pituitary stalk. His condition was well controlled by nasal DDAVP administration and 6 months later patient reduced spontaneously medication dose without clinical worsening. 8 months after clinical beginning, patient has become completely free from the need for medication to control clinical symptoms and urine concentrating function, as demonstrated by a re-evaluation study with water deprivation. A control Magnetic Resonance showed the regression of stalk enlargement. The clinical and radiological features of this case are discussed.

Adult↗
PubMed1998

[IgE levels in cord blood in an area of the Veneto region].

BACKGROUND: Cord blood IgE levels have been studied as a possible marker of allergy in infants but few studies are available in our Region. The aim of this paper was to test IgE levels in cord blood of 60 consecutive newborns in a restricted area of Veneto, to correlate cord blood IgE levels with family history of allergy and to verify the risk of contamination from mother's blood. METHODS: Cord blood was obtained from 60 consecutive newborns. Immunoglobulin levels (IgG, IgA, IgM, and IgE) were measured in cord blood of newborns and in serum of all mothers. Family history for allergy was previously investigated from the mothers. RESULTS: IgE were detectable in cord blood of 5 newborns but only 2 of them had positive family history for allergy which was pointed out in 11/60. In one of these cases the contamination of sample from mother's blood was postulated. IgG levels in newborn cord blood were higher than in mothers' blood and it was not related with IgE levels or other investigated factors. CONCLUSIONS: Only 6.6% of newborns in a restricted area of Veneto region have detectable IgE in cord blood whereas 18.3% of them have positive family history for allergy. Measurable levels of IgE in cord blood are not related with positive family history of allergy and are rarely influenced by mothers' blood contamination.

Adult↗
PubMed1997

Coronary stenting after rotational atherectomy in calcified and complex lesions. Angiographic and clinical follow-up results.

BACKGROUND: Treatment of calcified (in contrast to simple) lesions with PTCA has been associated with a lower success rate and more procedural complications. Rotablation can improve acute results, but the high restenosis rate remains a problem. The purpose of this study was to evaluate the clinical and angiographic outcome of patients with complex and calcified lesions treated with a combination of rotablation and stenting. METHODS AND RESULTS: Seventy-five consecutive patients with 106 lesions had rotablation prior to coronary stenting. Intravascular ultrasound-guided stenting was used without subsequent anticoagulation in 93% of patients. Procedural success was achieved in 93.4% of lesions. Acute stent thrombosis occurred in two lesions (1.9%), and subacute stent thrombosis in one lesion (0.9%). Angiographic follow-up was performed in 82.5% of lesions at 4.6 +/- 1.9 months with an angiographic restenosis rate of 22.5%. Clinical follow-up was performed in all patients at 6.4 +/- 3 months; target lesion revascularization was needed in 18% of lesions; Q-wave myocardial infarction occurred in 1.3%, coronary bypass surgery in 4.0%, and death in 1.3%. CONCLUSIONS: Optimal coronary stenting after rotablation in calcified and complex lesions can be performed with a high success rate, an acceptable rate of procedural complications, and a low rate of stent thrombosis. This approach was associated with a low incidence of angiographic restenosis compared with results usually obtained with other interventional strategies in calcified and complex lesion subsets.

Aged↗
PubMed1997

Enhanced expression of glucose-6-phosphate dehydrogenase in human cells sustaining oxidative stress.

Recent reports have demonstrated that glucose-6-phosphate dehydrogenase (G6PD) activity in mammalian cells is necessary in order to ensure cell survival when damage is produced by reactive oxygen intermediates. In this paper we demonstrate that oxidative stress, caused by agents acting at different steps in the biochemical pathway controlling the intracellular redox status, determines the increase in G6PD-specific activity in human cell lines of different tissue origins. The intracellular level of G6PD-specific mRNA also increases, with kinetics compatible with the induction of new enzyme synthesis. We carried out experiments in which cells were exposed to oxidative stress in the presence of inhibitors of protein or RNA synthesis. These demonstrated that increased G6PD expression is mainly due to an increased rate of transcription, with a minor but significant contribution of regulatory mechanisms acting at post-transcriptional levels. These results provide new information on the defence systems that eukaryotic cells possess in order to prevent damage caused by potentially harmful oxygen derivatives.

Carcinoma, Hepatocellular↗
PubMed1997

Results of a consecutive series of patients receiving only antiplatelet therapy after optimized stent implantation. Comparison of aspirin alone versus combined ticlopidine and aspirin therapy.

BACKGROUND: Previous studies have shown that stents can be inserted in coronary arteries of patients who are subsequently treated safely with antiplatelet therapy only (ticlopidine and/or aspirin) with a low incidence of stent thrombosis, provided that stent expansion is adequate and there are no other flow-limiting lesions present. However, it is unknown whether ticlopidine combined with aspirin is superior to aspirin alone in preventing stent thrombosis. METHODS AND RESULTS: From March 1993 through July 1995, 801 consecutive patients assigned to receive either aspirin therapy alone (ASA, 264 patients, 348 lesions) or a combination of ticlopidine and aspirin (TIC-ASA, 537 patients, 737 lesions) after a successful stent insertion, in most accomplished with intravascular ultrasound guidance, were evaluated retrospectively. At 1 month, there was no difference in the ASA group compared with the TIC-ASA group in the rate of any stent thrombosis (1.9% versus 1.9%; P = 1), subacute stent thrombosis (1.9% versus 1.3%; P = .5), cumulative major adverse clinical events (1.9% versus 2.0%; P = 1), and peripheral vascular complications (0.5% versus 0.2%; P = .3). Medication side effects that required termination of antiplatelet therapy occurred only in 1.9% of patients in the TIC-ASA group (P = .04). CONCLUSIONS: At 1-month clinical follow-up, stent thrombosis and other adverse clinical outcomes were not significantly different between the ASA and TIC-ASA groups. Medication side effects occurred only in patients treated with ticlopidine. These results provide further evidence of the safety of treatment with antiplatelet therapy only after optimal stent implantation and support the efficacy of aspirin alone in preventing stent thrombosis.

Angioplasty, Balloon↗
PubMed1997

New approach to quantitative angiographic assessment after stent implantation.

The new generation quantitative angiographic systems apply the interpolated technique to calculate the reference diameter at the site of the stenosis by integrating measurements of the segments proximal and distal to the stenosis. After stent implantation these measurements can be misleading as the treated segment, which is frequently larger than the adjacent not stented segments, is included in the measurements. The consequence is an overestimation of the reference diameter and the residual diameter stenosis. The present study was performed to compare this conventional technique of measurement with a new method which excludes the stented segment for the calculation of the reference diameter. Fifty-two lesions treated with poorly radiopaque stents (56% Palmaz-Schatz, 28% NIR, 10% Gianturco-Roubin, 6% Wallstent) expanded at high pressure (> = or 16 atm) were analyzed according to the conventional and stent excluded method. After stent implantation the reference diameter was 3.39 +/- 0.48 mm with conventional measurements and 3.02 +/- 0.45 mm with the stent excluded method (P < 0.05). The corresponding % diameter stenosis was 13 +/- 9 for the conventional technique and 1 +/- 13 for the stent excluded analysis (P < 0.05). The new approach to quantitative coronary analysis after stenting provides higher accuracy in reference diameter calculations and allows a more appropriate matching of stented segments with adjacent normal segments.

Angioplasty, Balloon, Coronary↗
PubMed1997

Age-related changes in body composition of healthy and osteoporotic women.

OBJECTIVES: The study was carried out to assess age-related changes of body composition and to evaluate the influence of lean and fat mass in bone mineral density of healthy and osteoporotic women. METHODS: 166 healthy women in premenopause (43.2 +/- 6.7 years), 591 healthy postmenopausal women (59.9 +/- 8.1 years) and 373 women with established involutive osteoporosis (66.2 +/- 7.8 years) were evaluated: bone mineral density (BMD) and soft tissue composition (fat mass, lean mass) were measured by a total body Lunar DPX device. RESULTS: no difference in lean mass was appreciated between the groups. Fat mass was significantly lower in premenopausal women (19.5 +/- 6.5 kg) and osteoporotic patients (18.8 +/- 5.2 kg) than in postmenopausal healthy women (21.8 +/- 5.7 kg). In premenopause weight, soft tissue mass and fat mass increased with age (P < 0.05). In postmenopause, lean mass decreased significantly in healthy women (P < 0.05). Fat mass was lower in the osteoporotics than in normals. Total BMD correlated significantly with fat and lean mass in all groups (P < 0.01). BMD/height ratio correlated significantly with fat mass (P < 0.01), not with lean mass. CONCLUSIONS: BMD is closely related to fat mass in healthy premenopausal and postmenopausal women, and in osteoporotic patients; osteoporotic patients and healthy premenopausal women are characterized by a lower fat mass than healthy postmenopausal women; fat mass may be considered one of the determinants of bone mass also in involutive osteoporosis.

Adipose Tissue↗
PubMed1997

High pressure assisted coronary stent implantation accomplished without intravascular ultrasound guidance and subsequent anticoagulation.

OBJECTIVES: The purpose of this study was to determine the efficacy of treatment with antiplatelet therapy and no anticoagulation after high pressure assisted coronary stent implantation performed without intravascular ultrasound (IVUS) guidance. BACKGROUND: Previous studies have shown that during IVUS-guided Palmaz-Schatz coronary stenting, it is safe to withhold anticoagulation when stent expansion has been optimized by high pressure balloon dilation. METHODS: Patients that had successful coronary stenting without IVUS guidance were treated with ticlopidine, 500 mg/day, and aspirin, 325 mg/day, for 1 month and then received only aspirin, 325 mg/day, indefinitely. Patients were not treated with warfarin (Coumadin) or heparin after successful stenting. Clinical and angiographic events were assessed at 1 month. RESULTS: A total of 201 intracoronary stents were implanted in 127 patients with 137 lesions. The average number of stents per lesion was 1.4 +/- 0.8, and the average number of stents per patient was 1.6 +/- 1.1. Stent deployment was performed for elective indications in 79% of procedures and for emergency indications in 21%. There were four stent thrombosis events for a per patient event rate of 3.1% and a per lesion event rate of 2.9%. CONCLUSIONS: After high pressure assisted stenting performed without IVUS guidance, there was an acceptable incidence of 3.1% of stent thrombosis with the combination of short-term ticlopidine and aspirin therapy and no anticoagulation. Although the study involved only 127 patients, the results support the relative safety of stenting without IVUS guidance and with antiplatelet therapy only in comparison to historical trials on stenting performed with postprocedure anticoagulation.

Anticoagulants↗
PubMed1997

Long-term clinical follow-up after successful repeat percutaneous intervention for stent restenosis.

OBJECTIVES: This study evaluated the long-term clinical outcome of successful repeat percutaneous intervention after in-stent restenosis. BACKGROUND: Recurrence of symptoms and angiographic restenosis after stent implantation are observed in 15% to 35% of cases. Repeat percutaneous treatment for in-stent restenosis has been shown to be safe, with high immediate success, but little is known about the long-term clinical outcome. METHODS: Clinical follow-up (minimum 9 months) was obtained in a consecutive series of 124 patients (127 vessels) presenting with stent restenosis who were successfully treated with repeat percutaneous intervention. RESULTS: Clinical follow-up was obtained in all 124 patients at a mean [+/-SD] of 27.4 +/- 14.7 months (range 9 to 66); a stress test was available in 88 patients (71%). Recurrence of clinical events occurred in 25 patients (20%) and included death from any cause in 2 patients (2%), target vessel revascularization in 14 (11%), myocardial infarction in 1 (1%) and positive stress test results or recurrence of symptoms (Canadian Cardiovascular Society class I to IV) treated medically in 8 (6%). Cumulative event-free survival at 12 and 24 months was 86.2% and 80.7%, respectively. Significant predictive factors of recurrence of clinical events were repeat intervention in saphenous vein grafts, multivessel disease, low ejection fraction and a < or = 3-month interval between stent implantation and repeat intervention. CONCLUSIONS: In-stent balloon angioplasty for stent restenosis in native vessels seems to be an effective method in terms of a low long-term clinical event rate.

Aged↗
PubMed1997

Fourier analysis of circadian blood pressure profile in secondary hypertension.

Different types of statistical methods have been used for circadian blood pressure (BP) rhythm analysis in secondary forms of hypertension. In the present study, we used the two-step statistical approach by Fourier analysis with four harmonics for the parametrization of the diurnal BP pattern in secondary hypertension. In 43 essential hypertensives (EH), eight patients with aldosterone producing adenoma (APA), 25 with idiopathic hyperaldosteronism (IHA), four with glucocorticoid remediable hyperaldosteronism (GRH) and seven with renovascular hypertension (RVH), 24-h ambulatory BP was measured. The diurnal BP and heart rate (HR) rhythm was present in more than 70% of patients with secondary hypertension, without significant differences with EH and despite the attenuation in the degree of the nocturnal BP fall. In conclusion, the statement that secondary hypertension is characterized by an abnormal diurnal rhythm of BP is a gross over-simplification. Our findings suggest that the two-step method with four harmonics Fourier analysis may represent a useful method and a more complete statistical approach to providing circadian parametrization of the 24-h profile in secondary hypertension.

Blood Pressure↗
PubMed1997

Molecular characterization of G6PD deficiency in Southern Italy: heterogeneity, correlation genotype-phenotype and description of a new variant (G6PD Neapolis).

We report on the molecular basis of glucose-6-phosphate dehydrogenase (G6PD) deficiency in Southern Italy (Campania region). Thirty-one unrelated G6PD-deficient males were analysed at DNA level for the presence of G6PD gene mutations. Nine different G6PD variants were identified, eight of which have already been described (Mediterranean, Seattle, two different A-, Santamaria, Cassano, Union and Cosenza). G6PD Mediterranean, Santamaria, A- and Union were associated with haemolytic episodes. G6PD Seattle, which is polymorphic in several populations, Cassano and Cosenza appeared to be asymptomatic. A new variant (G6PD Neapolis) is reported here. The 467(Pro-->Arg) substitution responsible for G6PD Neapolis is discussed in the light of the current 3D model of human G6PD and in comparison with other natural mutations which occur in the proximity of residue 467.

Genetic Heterogeneity↗
PubMed1997

Intracoronary stent implantation in native coronary arteries and saphenous vein grafts: a consecutive experience with six types of stents without prolonged anticoagulation.

OBJECTIVE: To analyze the results of implantation of six different intracoronary stents without the use of prolonged anticoagulation. MATERIAL AND METHODS: Between Mar. 30, 1993, and Jun. 30, 1995, 889 patients with 1,194 coronary or vein graft lesions underwent implantation of one of six types of stents-Palmaz-Schatz, Gianturco-Roubin, Wiktor, Micro, Cordis, or Wallstent. The patients were classified into seven groups on the basis of the type of stent that was implanted, including one group with combined use of two or more types of stents. Among the 851 patients with successful stent delivery and without major complications, 801 received only antiplatelet therapy, and 50 received a standard anticoagulation regimen. One-month clinical followup data were obtained in all patients, and clinical events were investigated. RESULTS: The mean number of stents was 1.8 per lesion and 2.4 per patient. Procedural success was achieved in 93% of the lesions. The clinical success rate at 1 month was 90%. Intravascular ultrasound assessment was performed in 90% of the lesions. The final minimal luminal cross-sectional area of the stent increased from 6.8 to 7.8 mm2 after intravascular ultrasound-guided optimization. Within 1 month, 16 stent thrombosis events (1.9%) occurred. No significant differences were noted in stent thrombosis rates among the various stent cohorts. Multivariate logistic regression analysis revealed that the final stent minimal luminal diameter measured by intravascular ultrasonography was the only variable associated with stent thrombosis. CONCLUSION: This study showed that six different stents could possibly be inserted without subsequent anticoagulation if optimal stent expansion and total lesion coverage were achieved.

Anticoagulants↗