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Biomedical subjects

L Pastor

Publications and source records attributed to L Pastor.

At least 19 recordsLinked to original sources
PubMed2006

Application of a fuzzy algorithm for pH control in a struvite crystallisation reactor.

A struvite crystallisation process is highly dependent on pH. To achieve a high phosphorus recovery as struvite it is important to have an accurate control of pH in the reactor. The high non-linear response of pH value makes manual pH control difficult. Therefore, a software based on fuzzy logic control (FLC) has been developed to maintain the pH at a set value in a stirred reactor to crystallise struvite. The FLC developed has been based on Larsen's inference. In order to confirm the improvement of the pH stability using FLC software, different experiments have been carried out with manual control of the pH value, and with the FLC software. It has been demonstrated that using FLC software allows a precise control of pH with high stability, optimises the process, and minimises the operator intervention.

Algorithms↗
PubMed2005

Is magnetic resonance imaging safe in cardiac pacemaker recipients?

Magnetic resonance imaging (MRI) is currently contraindicated in cardiac pacemaker (PM) recipients. The objectives of this prospective study were to (1) reassess the risks of performing an MRI scan in patients with PM, (2) compared the pacing functions before and after the exposure to MRI, and (3) monitor the development of possible adverse effects. Thirteen patients implanted with an Affinity DR model 5330 PMs (St. Jude Medical) connected to a Tendril model 1388 leads (St. Jude Medical) underwent 2.0 T-MRI for a variety of indications. All patients displayed a stable spontaneous rhythm at the time of the MRI scan and were not considered to be PM-dependent. The sensing and pacing functions were analyzed and the impedance of both leads was measured before and after the scan. The MRI scan was performed with all PM programmed in DDD mode. The sensing configuration was bipolar. All patients were monitored utilizing a standard electrocardiographic monitor and direct verbal communication. PM Inhibition, asynchronous pacing, or inappropriately rapid pacing was not observed. No patient reported discomfort, heat, or motion sensation at the PM implant site. There were no significant differences in the sensing, stimulation, AutoCapture threshold, and lead impedance measurements before and after MRI. The results of this study suggest that performing 2.0 T-MRI scans in patients with Affinity DR model 5330 PM connected to a Tendril model 1388 lead is safe.

Aged↗
PubMed2005

Lercanidipine in patients with chronic renal failure: the ZAFRA study.

OBJECTIVE: The objective was primary to evaluate the safe use of a new calcium channel blocker, lercanidipine, in patients with chronic renal failure (CRF). The secondary objective was to study the protective effect of calcium channel blocker on renal function in CRF patients previously treated with ACE inhibitors or angiotensin receptor blockers. DESIGN AND METHODS: The study recruited 203 CRF patients (creatinine >1.4 mg/dL for males, creatinine > 1.2 mg/dL for females, or creatinine clearance <70 mL/min). All patients were receiving ACE inhibitors (63.4%) or angiotensin II antagonist (36.6%) therapy, but they had higher blood pressure than recommended for CRF (130/85 mmHg). No patients were under diuretic treatment. Patients were clinically evaluated 1, 3, and 6 months after starting treatment with lercanidipine. Samples for urine and blood examination were taken during the examination. When needed, a third drug was added to the treatment, excluding diuretics. Creatinine clearance was measured using 24 h urine collection. RESULTS: 175 patients rendered valuable for the study (age 63.9+/-11.9 years, 52.9% males and 47.1% females). Blood pressure (BP) significantly decreased from 162+/-17/93+/-8.3 mmHg to 132+/-12/78+/-6 mmHg. 89.2% of patients showed a significant BP reduction, and 58.1% achieved optimal BP control (<130/85 mmHg). Seven patients (3.4%) showed untoward effects. Not one case of edema was detected, and the prevalence of adverse effects related to vasodilatation was extremely low (three patients, 1.48%). Plasmatic creatinine did not change (1.9+/-0.5 baseline versus 1.9+/-0.6 mg/dL), but creatinine clearance increased at the end visit (41.8+/-16.0 baseline versus 45.8+/-18.0 mL/min, p=0.019). Plasmatic cholesterol also decreased from 221+/-46 to 211+/-35 mg/dL (p=0.001). CONCLUSIONS: Lercanidipine showed a high antihypertensive effect in CRF patients. It has a good tolerability profile and showed an interesting effect on plasmatic lipids. An improvement in renal function, measured through creatine clearance, was detected.

Aged↗
PubMed2004

[Lercanidipine in diabetic patients with renal failure].

OBJECTIVE: To evaluate the safe use of a new calcium channel blocker, lercanidipine, in diabetic chronic renal failure (CRF) patients. DESIGN AND METHODS: The study recruited 42 diabetic CRF patients (creatinine > 1.4 mg/dl for males, creatinine > 1.2 mg/dl for females, or creatinine clearance < 70 ml/min). Mean age was 68.2 +/- 9.1 years. 53.8% were males and 46.2% females. Three patients were type 1 diabetics and 39 ones were type II. All patients were receiving ACE inhibitors (67.4%) or angiotensin II antagonist (32.6%) therapy but they had higher blood pressure than recommended for CRF patients (130/85 mmHg). No patients were under diuretic treatment. Patients were clinically evaluated 1, 3 and 6 months after starting treatment with lercanidipine. Samples for urine and blood examination were taken during the examination. When needed, a third drug was added to treatment, excluding diuretics. Creatinine clearance was measured using 24 h urine collection. RESULTS: BP significantly decrease from 163 +/- 18/90 +/- 8 mmHg to 134 +/- 12/77 +/- 9 mmHg. One half of patients showed significant reduction of blood pressure, 26.7% reached the target blood pressure (< 130/85 mmHg) and 20.0% gets optimal BP control (< 130/85 mmHg). No one patient showed untoward effects. No edema was detected nor adverse effects related to vasodilatation were found. Plasmatic creatinine did not change (1.9 +/- 0.5 baseline vs 1.8 +/- 0.5 mg/dl) and creatinine clearance increased at the end visit (40.1 +/- 14.5 baseline vs 45.4 +/- 18.2 ml/min) but the difference was not significant. Proteinuria was unchanged. CONCLUSIONS: Lercanidipine showed a good antihypertensive effect in diabetics CRF patients. It has a good tolerability profile and showed neutral effect on plasmatic lipids. Neither impairment of renal function nor increment in proteinuria were detected.

Aged↗
PubMed2002

[Effects of oxytetracycline on rat liver].

OBJECTIVES: This experimental project was designed to evaluate: a) the capacity of oxytetracycline to induce microvesicle steatosis in rat liver when administered over long time periods; b) whether female rats are more susceptible to this substance, and c) the possible ultrastructural alterations and their relation to the mechanisms of steatosis. METHODS: Sixty-two Wistar rats (31 males and 31 females) were distributed into six groups, two control groups and four experimental groups. The experiment lasted three months. Blood and hepatic tissue samples were extracted under anesthesia for morphologic study (optical and electron microscopy). RESULTS: Steatosis was of the microvesicular type with mainly periportal distribution. Steatosis developed in the treated groups and the degree was significantly greater in the females (p = 0.004). No relationship was found with dose. Ultrastructural study revealed microsome dilation in all experimental groups, with no differences according to sex. Despite the steatosis, no proliferation of peroxisomes or mitochondrial alterations were observed. CONCLUSIONS: Oxytetracycline produced predominantly periportal microvesicular hepatic steatosis, appearing mostly in the females. As a possible mechanism for tetracycline-induced steatosis, we postulate a decrease in mitochondrial, peroxisome and microsome function as a result of protein synthesis inhibition in these cell compartments.

Animals↗
PubMed2000

Laboratory evaluation of the effect of prophylaxis for thromboembolism with fractionated heparin in patients undergoing laparoscopic cholecystectomy.

OBJECTIVE: We studied the effect of prophylaxis for thromboembolism with low-molecular-weight heparin (LMWH) during hospitalization on the biological hemostasis system in patients who had undergone laparoscopic cholecystectomy. METHODS: This was a prospective paired cohort study without a control group (i.e., a before-after study). The subjects were 20 patients operated on laparoscopically for uncomplicated cholelithiasis. All patients received LMWH 2 h before the operation and 24 h after the first dose. Mean duration of surgery was 70 min. Pneumoperitoneum was accomplished at 14 mmHg, and all patients were operated on in the inverted Trendelenberg position (30 degrees). Patients were mobilized within 24 h, and were discharged within 48 h after surgery. As parameters of hemostasis we studied anti-Xa factor activity (anti-Xa), antithrombin III (AT III), partial active thromboplastin time (PTT) and fibrinogen. Samples were taken for laboratory analyses under basal conditions the day before the operation (first determination), 1 h after the first preoperative dose of LMWH was given (second), at the end of the operation (third), 24 h after surgery (fourth), and on postoperative day 7 (fifth). RESULTS: Mean basal values of all parameters were within the normal range. Mean anti-Xa activity was significantly higher in the second and third determinations than in the first and fifth measurements (p < 0.05). Mean PTT was significantly elevated on the second determination and decreased thereafter; however, none of the results differed significantly from the normal value. Mean AT III was significantly lower in the third determination in comparison with the first and fifth measurements. Fibrinogen was significantly higher in the fourth and fifth determinations than in the second and third measurements. Among all parameters and sampling times, the only values outside the normal range were anti-Xa activity on the second, third and fourth determinations. CONCLUSIONS: Plasma anti-Xa factor activity was increased preoperatively, and remained elevated for 24 h after surgery, returning to basal values on postoperative day 7. Partial thromboplastin time was slightly prolonged after the first dose of LMWH, indicating good antithrombotic action.

Adult↗
PubMed1999

Changes in hemostasis after laparoscopic cholecystectomy.

BACKGROUND: The aim of this work was to study hemostasis in laparoscopic cholecystectomy in order to determine if there are any changes that indicate a greater risk of thrombosis. METHODS: The study was carried out in 20 patients who underwent laparoscopic surgery for noncomplicated cholelithiasis. The average age was 59.4 years (range, 34-77). A total of 75% were female. Mean operation time was 70 min (ranges 35-120). Pneumoperitoneum at 14 mmHg was performed on all patients, who were positioned in the 30 degrees reverse Trendelenburg position. Postoperative mobilization was acheived in 24 hs and patients were discharged 48 hs after the operation. The control group was composed of 12 patients, who were evenly distributed by age, sex, and length of surgery. These patients underwent Bassini herniorraphy for inguinal hernia without any complications or relapse. The following hemostatic parameters were studied: prothrombin activity (PA), activated partial thromboplastin time (APTT), fibrinogen (Fg), anti-thrombin III (ATIII), plasma fibrinolytic activity (PFA), euglobulin fibrinolytic activity (EFA), and D-dimer (D-D). Samples were obtained at the following times: (a) under basal conditions the day before surgery, (b) preoperatively, (c) at the end of the operation, (d) 24 hs after the operation, and (e) On the 7th day following the operation. RESULTS: No patient showed any clinical manifestations of thromboembolic disease immediately after surgery or during a medium follow-up period of 16 months (range, 15-18 months). All hemostatic parameters values were within normal range in the basal samples of both groups. In both groups, the mean value of PA showed a significant decrease (p < 0.05) in the second, third, and fourth basal samples, returning to normal levels by the fifth determination. The mean value of fibrinogen decreased slightly in the second and third samples, increasing significantly with respect to the fourth and fifth determinations in both groups (p < 0.05). The mean value of APTT in both groups was slightly enhanced in the second and third determinations in relation to the first and fifth. The global activity of fibrinolysis (PFA and EFA) increased significantly in the third sample with respect to the other determinations in the group who had laparoscopic surgery (p < 0.005). Only EFA increased in the control group (p < 0.05). D-D decreased in the preoperative second determination followed by a significant enhancement immediate postoperatively (third), and 24 hs (fourth) (p < 0.05); it returned to normal basal values on the seventh day. No significant differences were found between the two groups. CONCLUSIONS: These results indicate that laparoscopic cholecystectomy leads to no greater activation of plasma coagulation than low-risk surgery. On the contrary, the increase of fibrinolytic activity in plasma would extend a certain degree of hypocoagulability during surgery, maintaining it for 24 hs and thus possibly reducing thromboembolic risk in patients undergoing this type of surgery.

Adult↗
PubMed1999

Effects of oxytetracycline on the rat exocrine pancreas.

OBJECTIVES: Given the appearance of pancreatitis attributed to tetracycline, as described in the literature, we have investigated its effect on the enzymatic content of pancreas and duodenal fluid and on pancreatic ultrastructure. We have evaluated possible differences between sexes and the relation of our findings with those described in the initial phases of acute pancreatitis, in the context of the acinar hypothesis. METHODS: With 128 Wistar rats (63 male and 65 female), 3 groups were established: control (group I) experimental animals treated with oxytetracycline intramuscularly, 15 and 30 mg/kg/d (groups II and III, respectively). Before sacrifice, half of the rats in each group were stimulated with cholecystokinin. Blood, pancreatic tissue (for enzyme dosage and morphological study), and duodenal fluid were extracted following anesthesia. RESULTS: The stimulated males of group III presented lower amylase levels in pancreatic tissue and duodenal fluid (P < 0.003). Just the opposite occurred in female rats. A similar tendency was observed with other enzymes (lipase and trypsin). Zymogen granule counts, appearance of immature granules, and dilation of ergastoplasm were more frequent in the stimulated animals. CONCLUSIONS: Oxytetracycline seems to induce morphofunctional changes in rat pancreas, which differ according to sex. In the female, enzyme accumulation that could predispose intracellular activation seems to exist, as well as the ultrastructural findings described in initial phases of acute experimental pancreatitis. This agrees with the greater frequency of pancreatitis in women undergoing tetracycline treatment described in the literature. In contrast, for males the findings were more compatible with decrease of protein synthesis. This would make them less susceptible to crinophagy phenomena and, thus, to acute pancreatitis in the context of the acinar or lysosome hypothesis.

Amylases↗
PubMed1998

New antifungals selected by molecular topology.

Molecular topology has been applied to find the new lead antimycotic compounds. Among the selected compounds stands out 3,3'-(4,4'-Biphenylene)bis(2,5-diphenyl-2H-tetrazolium chloride), Benztropine mesylate and Dicyclopentamethylenethiuram disulphide, with minimum inhibitory concentrations between 1.6 and 2 micrograms/mL.

Antifungal Agents↗
PubMed1995

[Anatomopathologic changes in the distal esophagus following proximal gastric vagotomy. Experimental study].

In order to determine the causes of postvagotomy dysphagia, we examined microscopic changes in the lower esophagus after a proximal gastric vagotomy. Forty dogs were divided into 4 groups (n = 10). Group I was used as control. In group II, the effect of denervation was studied by means of transthoracic vagotomy. In group III, the effect of mechanical traction of the lower esophagus was studied, without denervation or surgical manoeuvres. In group IV, the effect of denervation, esophageal traction and the surgical manoeuvres, of proximal gastric vagotomy was examined. No periesophageal hematomas or fibrosis was found. Degenerative nerve phenomena were found with no significant differences in the three groups. In groups III and IV, lesions of the esophageal muscular layer were observed, without significant differences. Chronic inflammatory changes and fibrosis were also encountered being more intense and significantly more frequent in group IV. We conclude that the surgical manoeuvers necessary to obtain denervation of the cardioesophageal function during proximal gastric vagotomy, could be responsible for the appearance of post-vagotomy dysphagia.

Animals↗