PubMed Health⌕ Search

Biomedical subjects

L A Sechi

Publications and source records attributed to L A Sechi.

At least 37 records · Page 2Linked to original sources
PubMed2001

Molecular basis of rifampin and isoniazid resistance in Mycobacterium bovis strains isolated in Sardinia, Italy.

Fourteen of 22 (68%) Mycobacterium bovis strains isolated from cattle in Sardinia were found to be resistant to rifampin and isoniazid. Analysis of the rpoB and the katG, oxyR-ahpC, and inhA gene regions of these strains was performed in order to investigate the molecular basis of rifampin and isoniazid resistance, respectively. The most frequent mutation, encountered in 6 of 10 strains (60%), was in the rpoB gene; it occurred, at codon position 521 and resulted in leucine changed to proline. This suggests that codon 521 may be important for the development of rifampin resistance in M. bovis. Resistance to isoniazid is associated in Mycobacterium tuberculosis with a variety of mutations affecting one or more genes. Our results confirm the difficulty of interpreting the sequence variations observed in clinical strains of M. bovis. M. bovis strains isolated from the same geographic area showed similar mutations within the genes responsible for rifampin and isoniazid resistance. Our results represent the first study to elucidate the molecular genetic basis of drug resistance in M. bovis isolated from cattle.

Animals↗
PubMed2001

Relationship of lipoprotein(a) to variables of coagulation in hypertensive subjects.

BACKGROUND: Coagulation factors are independent predictors of cardiovascular damage in the general population. The purpose of this study was to investigate the relationships between general cardiovascular risk factors, lipoprotein(a) (Lp(a)), and some hemostatic variables, and to characterize the isoforms of apolipoprotein(a) (apo(a)) in hypertensive subjects. METHODS: Plasma lipids, apolipoproteins, Lp(a), apo(a) isoforms, fibrinogen, and parameters that directly reflect the coagulation activation were measured in 389 untreated essential hypertensive patients recruited at a hypertension clinic. Hypertensive patients were compared with 323 normotensive controls. RESULTS: In normotensive subjects, Lp(a) concentrations were significantly correlated with fibrinogen (r = 0.138; P < 0.02) but not D-dimer (r = 0.074; not significant). In hypertensive subjects, log Lp(a) concentrations were significantly correlated with age (r = 0.127; P < 0.02), apo-B (r = 0.128; P < 0.02), plasma fibrinogen (r = 0.193; P < 0.001), and fibrin D-dimer (r = 0.200; P < 0.001) levels, but not with body mass index, blood pressure, cholesterol, triglycerides, apo-AI, prothrombin fragment 1 + 2, and antithrombin III. The relationship of Lp(a) with fibrinogen (male: r = 0.198, P < 0.002; female: r = 0.177, P < 0.01) and D-dimer (male: r = 0.211, P < 0.002; female: r = 0.188, P < 0.01) was significant in both sexes, whereas the relationship of Lp(a) with age and apo-B was found only in males. Multivariate analysis showed that both fibrinogen and D-dimer were independently related with Lp(a). Elevated fibrinogen, D-dimer, and Lp(a) levels were significantly and independently associated with clinical evidence of atherosclerotic disease. Apo(a) phenotypes were analyzed to investigate the genetic background of the relationships between Lp(a) and coagulation parameters. In both hypertensive and normotensive subjects, Lp(a) levels were inversely correlated with apo(a) isoform protein size, whereas fibrinogen and D-dimer concentrations were comparable in patients with apo(a) isoforms of different size. CONCLUSIONS: The relationship between Lp(a) and clotting variables is significantly stronger in hypertensive than in normotensive subjects, providing a compelling argument for accelerated progression of atherothrombosis in these patients.

Adult↗
PubMed2001

Molecular analysis of Klebsiella pneumoniae strains isolated in pediatric wards by ribotyping, pulsed field gel electrophoresis and antimicrobial susceptibilities.

The purpose of this study was to investigate the usefulness of different molecular typing techniques in the surveillance and control of the spread of extended-spectrum-beta-lactamase-(ESBL) producing Klebsiella pneumoniae in the pediatric department of the "Agostino Gemelli" hospital of the Catholic University in Rome, over a period of nine months. The strains were characterized by ribotyping using HindIII as restriction enzyme and pulsed field gel electrophoresis (PFGE) using XbaI as endonuclease. Sixty six K. pneumoniae clinical strains were isolated during this period, the first 32 were isolated in the summer of 1998. Among these first isolates, ribotyping generated 26 different patterns whereas PFGE produced 16 patterns. The remaining 34 strains were isolated during January and April 1999 and all of them were ESBL producers. Ribotyping clustered the strains into 6 patterns whereas PFGE generated only 3 patterns. PCR revealed the presence in 10 isolates of both bla(TEM) and bla(SHV) genes and 24 strains carried only the bla(SHV) gene. In our experience ribotyping revealed a higher power of differentiation with respect to PFGE and was of great help in the surveillance of the infection.

Cross Infection↗
PubMed2000

Abnormalities of coagulation in hypertensive patients with reduced creatinine clearance.

PURPOSE: The prothrombotic state that occurs in uremic patients may increase their cardiovascular risk. We studied hypertensive patients with mild-to-moderate impairment of renal function to determine if they had evidence of abnormalities in the coagulation system. SUBJECTS AND METHODS: Renal function was assessed in 382 patients with essential hypertension, in whom 24-hour creatinine clearance, urinary protein excretion, and microalbuminuria were measured. We evaluated the function of the coagulation system by measurement of platelet counts, prothrombin time, partial thromboplastin time, and plasma antithrombin III, fibrinogen, D-dimer, and prothrombin fragment 1 + 2 levels. RESULTS: Impaired renal function, defined as a creatinine clearance of 30 to 89 mL per minute per 1.73 m(2) of body surface area, was found in 168 (44%) of the patients. Age, blood pressure, duration of hypertension, and plasma levels of fibrinogen, D-dimer, prothrombin fragment 1 + 2, and lipoprotein(a) were significantly greater in these patients than in those with normal renal function; these differences persisted after adjustment for potential confounders. Creatinine clearance was significantly and inversely correlated with levels of plasma fibrinogen (Spearman's rho = -0.26, P <0.001), D-dimer (rho = -0.33, P <0.001), and prothrombin fragment 1 + 2 (rho = -0.20, P <0.001). Levels of plasma fibrinogen (P = 0.009) and D-dimer (P = 0.003) were correlated with renal function independent of age, blood pressure, duration of hypertension, triglyceride level, urinary protein excretion, and erythrocyte sedimentation rate. Lipoprotein(a) levels were correlated with fibrinogen (rho = 0.16, P = 0.003) and D-dimer (rho = 0.26, P <0.001) levels. CONCLUSIONS: Increased plasma levels of fibrinogen, D-dimer, and prothrombin fragment 1 + 2 are present in hypertensive patients with mildly decreased creatinine clearance, suggesting that the coagulation system is activated in these patients.

Adult↗
PubMed2000

In vitro adherence of Staphylococcus epidermidis to polymethyl methacrylate and acrysof intraocular lenses.

PURPOSE: To investigate the adherence of one clinically relevant ocular isolate of Staphylococcus epidermidis to polymethyl methacrylate (PMMA) and Acrysof (Alcon Surgical, Fort Worth, TX) intraocular lenses (IOLs). DESIGN: Experimental study. PARTICIPANTS: The authors examined the in vitro adherence of one clinically relevant ocular isolate of S. epidermidis. Adherence was tested on 12 PMMA IOLs and 12 Acrysof IOLs. METHODS: Six IOLs (three of each type) were placed in different test tubes containing bacterial suspension (10(8) cfu/ml) and incubated at 37 degrees C. At different times (3 minutes, 30 minutes, and 90 minutes), each IOL type was removed from the test tube, rinsed in sterile phosphate-buffered saline, and transferred into sterile brain-heart infusion broth. The broth with the IOL was sonicated on low power for 3 minutes to remove adhered bacteria. Two serial 10-fold dilutions of the broth containing the dislodged bacteria were plated on mannitol agar plates. The plates were incubated overnight at 37 degrees C and then bacterial colonies were counted. All assays were performed in triplicate. Additional lenses (three of each type) were incubated with S. epidermidis for different times (3 minutes, 30 minutes, and 90 minutes) and then examined with scanning electron microscopy. MAIN OUTCOME MEASURES: The number of adhered bacteria per area (mm ) of IOL optic was calculated. Statistical analysis included calculation of arithmetic means and 95% confidence intervals (t test). RESULTS: Direct counting of viable adherent bacteria released by sonication showed that the amount of adhered bacteria per area of IOL optic after 3, 30, and 90 minutes' incubation in S. epidermidis suspension was 0.1 x 10(2)/mm2, 3.6 x 10(2)/mm2, and 11 x 10(2)/mm2 (PMMA IOLs), and 4.4 x 10(2)/mm2, 3.1 x 10(2)/mm2, and 2.3 x 10(2)/mm2 (Acrysof IOLs). Direct counting of adherent bacteria in scanning electron microscopy photographs revealed that the total amount of adhered bacteria per area of IOL optic after 3, 30, and 90 minutes' incubation in S. epidermidis suspension was 1.1 x 10(2)/mm2, 4.4 x 10(2)/mm2, and 5.5 x 10(2)/mm2 (PMMA IOLs) and 13 x 10(2)/mm2, 33.9 x 10(2)/mm2, and 72 x 10(2)/mm2 (Acrysof IOLs). CONCLUSIONS: Results suggest that in vitro adherence of S. epidermidis to IOLs is influenced by IOL materials. After 3 minutes' incubation, Acrysof IOLs appeared to be more permissive to S. epidermidis adherence than PMMA IOLs. The difference was statistically significant (P < 0.05). However, at 90 minutes, Acrysof IOLs had a lower viable bacterial count than did the PMMA IOLs. Bacterial adherence appeared to be greater in areas with surface irregularities. Adherence of S. epidermidis to IOLs may play a role in the pathogenesis of some forms of endophthalmitis after cataract surgery.

Acrylic Resins↗
PubMed2000

Adherence of ocular isolates of staphylococcus epidermidis to ACRYSOF intraocular lenses. A scanning electron microscopy and molecular biology study.

PURPOSE: To investigate the adherence of two clinically relevant ocular isolates of Staphylococcus epidermidis to ACRYSOF intraocular lenses (IOLs) (Alcon Surgical, Fort Worth, Texas) and to determine whether the strains under study carried the intercellular adhesion (ica) locus, which encodes production of S. epidermidis antigens mediating adherence to biomaterials. DESIGN: Experimental study. PARTICIPANTS: The authors examined the in vitro adherence of two clinically relevant ocular isolates of S. epidermidis (S. epidermidis 1 and S. epidermidis 2). Adherence was tested on six ACRYSOF IOLs. METHODS: Three IOLs were placed in three separate test tubes containing 5 ml of S. epidermidis 1 suspension, and three other IOLs were placed in three test tubes containing 5 ml of S. epidermidis 2 suspension. At different times (3, 30, and 90 minutes), the IOLs were removed from the test tubes and rinsed in sterile phosphate buffered solution. The lenses were then fixed in glutaraldehyde, postfixed in osmium tetroxide, and serially dehydrated in ethyl alcohol. After critical point drying, they were sputter-coated with gold and then examined with a scanning electron microscope. In addition, polymerase chain reaction amplification was used to investigate whether the isolates under study carried the ica locus. MAIN OUTCOME MEASURES: The number of adhered bacteria per area (square millimeters) of IOL optic was calculated. Statistical analysis included calculation of arithmetic means and 95% confidence intervals (t test). Polymerase chain reaction amplification products were visualized in ethidium bromide-stained agarose gel. RESULTS: Direct counting of adherent bacteria in scanning electron microscopy photographs revealed that the total amount of adhered bacteria per area of IOL optic after 3, 30, and 90 minutes of incubation in bacterial suspension was 1306/mm(2), 3389/mm(2), and 7195/mm(2) (S. epidermidis 1) and 778/mm(2), 1056/mm(2), and 3861/mm(2) (S. epidermidis 2). Differences at 30 and 90 minutes were statistically significant (P: = 0.01 and 0.02, respectively). Polymerase chain reaction amplification revealed that S. epidermidis 1 contained the ica locus, whereas S. epidermidis 2 was ica negative. CONCLUSIONS: Different ocular isolates of S. epidermidis may differ significantly with regard to adherence to ACRYSOF IOLs. Adherence appeared to be greater when the bacterial DNA contained the ica locus. Strains of S. epidermidis carrying the ica locus may play an important role in the pathogenesis of some forms of endophthalmitis occurring after cataract surgery.

Acrylates↗
PubMed2000

Distribution of Vibrio cholerae virulence genes among different Vibrio species isolated in Sardinia, Italy.

The members of the genus Vibrio include harmless aquatic strains as well as strains capable of causing epidemics of cholera. Diarrhoea caused by Vibrio cholerae is attributed to cholerae enterotoxin (CT) codified by the ctx operon and regulated by a number of virulence genes such as toxT, toxR and toxS. Fifty-two Vibrio strains were isolated from different aquatic environments in and around Sardinia and searched by PCR for the presence of ctxA, zot, ace, toxR, toxS, toxT, tcpA and vpi virulence genes in the genomes of the isolates. The toxR operon was found in 27 Vibrio alginolyticus strains out of 42 analysed, in three out of four V. cholerae non-O1 strains and in three Vibrio parahaemolyticus isolates. A positive amplification for the virulence pathogenic island (vpi) was produced by five V. alginolyticus strains. Finally, the ace expected amplification fragment was found in two V. alginolyticus isolates whereas the amplification with zot primers produced the expected fragment in one V. alginolyticus isolate. Differentiation of these strains with a PCR fingerprinting technique revealed no association between the presence of virulence genes and a particular fingerprinting pattern. Although most Vibrio species are considered non-pathogenic or only potentially harmful to humans, the finding of V. cholerae virulence genes in other members of the genus Vibrio, and the recent reports of the creation and evolution of pandemic strains of V. cholerae, may give a new perspective to the significance of these results.

DNA Fingerprinting↗
PubMed2000

The tissue renin-angiotensin system in rats with fructose-induced hypertension: overexpression of type 1 angiotensin II receptor in adipose tissue.

OBJECTIVE: Fructose feeding induces hypertension, insulin-resistance and hypertriglyceridemia in Sprague-Dawley rats. The mechanisms of fructose-induced hypertension are as yet unknown. Here we investigate the effects of fructose feeding and of varying salt intake on blood pressure, glucose tolerance, plasma renin activity, and tissue angiotensinogen, renin, and AT1 receptor mRNA levels in this model of hypertension. DESIGN AND METHODS: To investigate the role of the renin-angiotensin system in fructose-induced hypertension we measured angiotensinogen, renin and angiotensin II type 1 (AT1) receptor mRNA levels in tissues of Sprague-Dawley rats that were fed either standard rat chow or a diet containing 66% fructose. RESULTS: Blood pressure (P < 0.05) and triglyceride (P < 0.01) levels were significantly greater in the fructose-fed animals. Plasma glucose and insulin responses to an oral glucose load were significantly greater (P< 0.05) in fructose-fed than control rats. Angiotensinogen mRNA levels in liver and fat, and renin mRNA levels in kidney did not differ between fructose-fed and control animals. Levels of AT1 receptor mRNA were significantly greater in the fat obtained from fructose-fed rats than in that from control rats (P< 0.05), but this was not so in the kidney. To determine whether fructose-induced hypertension is dependent on dietary salt content, rats were fed standard rat chow and a fructose-enriched diet with low and high sodium chloride concentrations. Blood pressure increased significantly (P< 0.05) only in the fructose-fed rats receiving the high-salt diet Similarly, increased AT1 receptor mRNA levels were observed only in the fructose-fed rats that were maintained on the high-salt diet CONCLUSIONS: Fructose feeding induces hypertension in normal- or high-salt fed animals and it is associated with an increased expression of the AT1 receptor in adipose tissue. These findings suggest that AT1 receptors might play a role in the pathophysiology of metabolic and hemodynamic abnormalities induced by fructose feeding.

Adipose Tissue↗
PubMed2000

Lipoprotein (a), haemostatic variables and cardiovascular damage in hypertensive patients.

OBJECTIVE: Lipoproteins and coagulation factors are independent predictors of atherothrombotic events in the general population and their interaction may contribute to the development of cardiovascular damage. This study was designed to assess relationships between lipoproteins, haemostatic variables, and atherosclerotic complications in hypertensive patients. METHODS: In 389 untreated essential hypertensive patients recruited at a hypertension clinic, we measured plasma lipids, apolipoproteins, lipoprotein (a), apolipoprotein (a) isoforms, fibrinogen, and parameters that directly reflect the coagulation activation. Hypertensive patients were compared to 92 normotensive controls. RESULTS: Univariate analysis showed log lipoprotein (a) concentrations to be significantly correlated with age (P< 0.02), apolipoprotein B (P< 0.02), plasma fibrinogen (P< 0.001), and fibrin D-dimer (P< 0.001) levels, but not with body mass index, blood pressure, dietary fat intake, cholesterol, triglycerides, apolipoprotein Al, prothrombin fragment 1 + 2, and antithrombin III. The relationship of lipoprotein (a) with fibrinogen and D-dimer was present in both sexes, whereas the relationship of lipoprotein (a) with age and apolipoprotein B was found only in males. Multiple regression analysis showed that both fibrinogen and D-dimer were independently related with lipoprotein (a). Elevated fibrinogen, D-dimer, and lipoprotein (a) levels were significantly and independently associated with clinical evidence of atherosclerotic disease. To investigate whether the relationships of lipoprotein (a) with coagulation parameters are genetically determined, we analysed apolipoprotein (a) phenotypes in a subset of 188 hypertensive patients. While lipoprotein (a) levels were inversely correlated with apolipoprotein (a) isoform protein size, both fibrinogen and D-dimer concentrations were comparable in patients with apolipoprotein (a) isoforms of different size. CONCLUSIONS: This study demonstrates a relationship between lipoprotein (a) and clotting variables in hypertensive patients that may contribute to atherosclerotic damage in these patients. There is no evidence of a genetic background for this relationship.

Adult↗
PubMed2000

Distribution of a specific 500-base-pair fragment in mycobacterium bovis isolates from Sardinian cattle.

Amplification of a specific, 500-bp fragment from Mycobacterium bovis isolates and use of the fragment to differentiate between Mycobacterium tuberculosis and M. bovis was previously reported (J. G. Rodriguez, G. A. Meja, P. Del Portillo, M. E. Patarroyo, and L. A. Murillo, Microbiology 141:2131-2138, 1995). In the present study, 30 M. bovis isolates from Sardinian cattle were examined for the presence of this 500-bp fragment; 4 of the 30 isolates lacked the fragment. This result indicates that identification of M. bovis strains by amplification of the 500-bp sequence may lead to false-negative results.

Animals↗
PubMed2000

Relationship of fibrinogen levels and hemostatic abnormalities with organ damage in hypertension.

Elevated plasma levels of fibrinogen and activated coagulation pathways are risk factors of cardiovascular disease in the general population. In a cross-sectional study of a case series, we investigated the relationship between fibrinogen and hemostatic markers with target-organ damage (TOD) in patients with arterial hypertension. Prothrombin time, partial thromboplastin time, fibrinogen, fibrin D-dimer, prothrombin fragment 1+2 (F1+2), and antithrombin III were measured in 352 untreated patients with mild to moderate essential hypertension and 92 normotensive controls. Staging of TOD was assessed according to W.H.O. guidelines by clinical evaluation and laboratory tests including measurements of creatinine clearance, proteinuria, ophthalmoscopy, electrocardiography, echocardiography, and ultrasound examination of major arteries. F1+2 concentrations were significantly greater in hypertensive patients than normotensive controls and were positively correlated with blood pressure. Age, blood pressure levels, duration of hypertension, smoking, HDL-cholesterol, triglycerides, and plasma fibrinogen, fibrin D-dimer, and F1+2 levels were significantly related to the presence and severity of TOD in univariate analysis. Plasma fibrinogen and D-dimer levels were related to organ damage independent of age, blood pressure, duration of hypertension, and smoking status. Separate analysis indicated significant association of fibrinogen and D-dimer levels with cardiac, cerebrovascular, peripheral vascular, and renal damage. In conclusion, elevated plasma levels of fibrinogen and a prothrombotic state are associated with the presence and severity of TOD in patients with essential hypertension and may contribute to the development of atherosclerotic disease in these patients.

Aged↗
PubMed2000

Increased fibrinogen levels and hemostatic abnormalities in patients with arteriolar nephrosclerosis: association with cardiovascular events.

Increased plasma fibrinogen levels and hemostatic abnormalities suggestive of a prothrombotic state are present in patients with end-stage renal failure and could contribute to increased cardiovascular morbidity in these patients. We investigated the relationship between abnormalities of the hemostatic system and the degree of renal failure and whether these abnormalities are associated with increased prevalence of cardiovascular events in patients with arteriolar nephrosclerosis. In 425 patients recruited at a hypertension clinic we assessed the renal function by creatinine clearance, urinary protein excretion, and microalbuminuria, the prevalence of atherosclerotic disease, and measured prothrombin time, activated partial thromboplastin time. fibrinogen, prothrombin fragment 1+2 (F1+2), D-dimer, and antithrombin. Early impairment of renal function (creatinine clearance, 30 to 89 ml/min per 1.73 m2 of body surface area) caused by arteriolar nephrosclerosis was found in 172 patients. Patients with early renal failure were significantly older and had significantly greater values of blood pressure, plasma fibrinogen, F1+2, and D-dimer than patients with normal renal function. Elevated D-dimer and fibrinogen levels were independently associated with the presence of decreased creatinine clearance. Log fibrinogen, log F1+2, and log D-dimer were inversely correlated with creatinine clearance. The prevalence of coronary artery, cerebrovascular, and peripheral vascular disease was significantly greater in patients with mild renal failure than in those with normal renal function. Elevated levels of fibrinogen and D-dimer were associated with the presence of atherosclerotic disease independent of renal function and other risk factors. In conclusion, changes in hemostatic parameters occur early in the course of renal failure in patients with arteriolar nephrosclerosis, suggesting a prothrombotic state that may contribute to the risk for atherosclerotic disease at all levels of renal function.

Adult↗