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Biomedical subjects

J A Guerrero

Publications and source records attributed to J A Guerrero.

At least 19 recordsLinked to original sources
PubMed2005

Adaptive monogenic filtering and normalization of ESPI fringe patterns.

A technique is presented for filtering and normalizing noisy fringe patterns, which may include closed fringes, so that single-frame demodulation schemes may be successfully applied. It is based on the construction of an adaptive filter as a linear combination of the responses of a set of isotropic bandpass filters. The space-varying coefficients are proportional to the envelope of the response of each filter, which in turn is computed by using the corresponding monogenic image [Felsberg and Sommer, IEEE Trans. Signal Process. 49, 3136 (2001)]. Some examples of demodulation of real Electronic Speckle Pattern Interferometry (ESPI) images patterns are presented.

Algorithms↗
PubMed2005

Flavonoids inhibit platelet function through binding to the thromboxane A2 receptor.

BACKGROUND: Dietary flavonoids are known for their antiplatelet activity resulting in cardiovascular protection, although the specific mechanisms by which this inhibition occurs has not been fully established. OBJECTIVE: The aim of this study was to investigate the interaction of nine flavonoids representative of various chemical classes, with platelet responses dependent on thromboxane A(2) (TxA(2)) generation and on receptor antagonism, and to analyze the structural requirements for such effects. METHODS: The effect of several types of flavonoids on platelet aggregation, serotonin release, and TxA(2) generation was investigated. Competitive radioligand binding assays were used to screen for affinity of these compounds to TxA(2) receptors. RESULTS: Flavones (apigenin and luteolin) and isoflavones (genistein) abrogated arachidonic acid and collagen-induced platelet responses, such as aggregation and secretion, with a less substantial effect on TxA(2) synthesis. These compounds were identified as specific ligands of the TxA(2) receptor in the micromol L(-1) range, this effect accounting for antiplatelet effects related to stimulation with those agonists. Tight binding of flavonoids to the human TxA(2) receptor relies on structural features such as the presence of the double bond in C2-C3, and a keto group in C4. CONCLUSIONS: The inhibition by specific flavonoids of in vitro platelet responses induced by collagen or arachidonic acid seems to be related, to a great extent, to their ability to compete for binding to the TxA(2) receptor. Therefore, antagonism of this TxA(2) receptor may represent an additional mechanism for the inhibitory effect of these compounds in platelet function.

Apigenin↗
PubMed2004

Genetic variants of the extra-large stimulatory Gs protein alpha-subunit and risk of thrombotic and haemorrhagic disorders.

A polymorphism of the gene encoding the extra-large stimulatory G-protein alpha-subunit (XLalphas), originally identified in three patients with a bleeding tendency, involved a 36-bp insertion and two missense changes. A paternally-inherited insertion displayed a moderate platelet Gsalpha over-expression, which lead to platelet hypo-reactivity. These data prompted us to investigate the genetic, functional and clinical relevance of this polymorphism in the Mediterranean population. We included 414 healthy subjects and three case/control studies: 263 consecutive patients with a first episode of primary intracerebral haemorrhage, 195 patients with deep venous thrombosis, and 104 patients with cerebrovascular disease. Controls were selected by approximating criteria to match selected risk factors to patients. Moreover, we performed studies of platelet function. We developed a simple method to determine the methylated allele, by digestion of genomic DNA with Sma I before polymerase chain reaction amplification. We identified two new rare variants, resulting from the loss of repeat units 7 and 5. The AB genotype was present in 3.6% of healthy population and the prevalence of the B allele was similar among cases and controls. Accordingly, the non-methylated B allele did not modify either the expression of platelet Gsalpha or the platelet response to Gs-agonists. Thus, our study suggests a minor functional role of XLalphas polymorphism in thrombotic or in haemorrhagic disorders.

Aged↗
PubMed2004

Evaluation of refrigerated platelet concentrates supplemented with low doses of second messenger effectors.

With the goal of producing haemostatically effective platelet concentrates (PCs) with a longer shelf-life, we aimed to identify a simple combination of platelet inhibitors, with a low pharmacological load, which could avoid the unacceptable loss of platelets stored under refrigerated conditions. PCs stored with different combinations of second messenger effectors were analysed at days 5, 10 and 15 of storage and compared with those supplemented with ThromboSol--a combination of six platelet inhibitors that protects cells from cold damage. The following parameters were analysed: platelet counts, biochemical parameters (glucose, pH, bicarbonate, lactate), cell lysis (lactic dehydrogenase, LDH), membrane glycoproteins (GPs), platelet aggregation, fibrinogen binding and hypotonic shock response. We characterized the combination of amiloride and sodium nitroprusside (at 1/2 the dose included in ThromboSol). This was found to be similar to ThromboSol and superior to nontreated units in the prevention of cold-induced platelet aggregation at day 15 of storage (maintenance of 78% and 80% of initial platelet counts, respectively), preservation of GPIbalpha (11% and 12% better maintenance of mean fluorescence intensity compared with control units, respectively), and reduced cell lysis (13% and 11% decrease in supernatant LDH, respectively). The reduced pharmacological load with the identified solution compared with ThromboSol is an argument in favour of the potential use of these agents when designing strategies to improve PC storage.

Blood Platelets↗
PubMed2000

Determination of linear alkylbenzenesulfonates in wastewater treatment plants and coastal waters by automated solid-phase extraction followed by capillary electrophoresis-UV detection and confirmation by capillary electrophoresis-mass spectrometry.

Linear alkylbenzenesulfonates (LASs) were determined in wastewaters and coastal waters by solid-phase extraction, using two different sample preparation protocols depending on the sample treated, followed by capillary electrophoresis and ultraviolet detection (CE-UV). The linear range of the proposed method varied from 3 to 53 and from 25 to 495 microg/l, depending on the compound, with a limit of detection of 1 microg/l when 250 ml of coastal water was preconcentrated. [M-H]- ions were used for CE-MS confirmation after quantification by CE-UV. CE-MS diagnostic ions were the same ones used in LC-electrospray (ESI) MS and corresponded to m/z 297, 311, 325 and 339 for C10, C11, C12 and C13 LASs, respectively. LASs were determined in wastewater samples of the influent and effluent of three wastewater treatment plants (WWTPs), two of them using biological treatment with secondary settlement and receiving mainly domestic wastewaters whereas one of the plants was operated with physicochemical treatment and received mainly industrial wastewaters. LASs were also analyzed in two samples from coastal waters of the bay of Cadiz (Spain) receiving untreated domestic effluents. All samples were also analyzed by LC-ESI-MS and the results are compared with the CE-UV method developed in this work. The concentration levels of total LASs varied from 988 to 1309 microg/l in the influents of WWTPs, whereas in the effluents the concentrations varied from 136 to 197 microg/l. The levels of LASs in coastal wastewaters of the bay of Cadiz varied from 739 to 911 microg/l, indicating that the wastewaters discharged into the bay did not undergo any treatment at all.

Alkanesulfonic Acids↗
PubMed2000

Reproducibility of time-domain and three different frequency-domain techniques for the analysis of the signal-averaged electrocardiogram.

Because time-domain (TD) analysis of the signal-averaged ECG (SAECG) has some limitations that limit its use, several frequency-domain analysis techniques were developed in an attempt to improve the diagnostic ability of the SAECG. However, it is not known how reliable these techniques are at detecting late potentials. This prospective study compares the short-term reproducibility of 4 analysis techniques: TD analysis, spectral temporal mapping (STM), spectral turbulence analysis (STA), and acceleration spectrum analysis (ASA), in a large series of normal patients and post-myocardial infarction (MI) patients. Two consecutive SAECGs were recorded in 634 patients that were divided into 3 groups: 117 remote MI patients undergoing programmed electrical stimulation for the inducibility of ventricular tachycardia (Group 1), 407 consecutive acute MI survivors (Group 2), and in 110 healthy volunteers (Group 3). The diagnostic reproducibility of the 4 techniques was evaluated by comparing rates of inconsistent results (1 normal and the other abnormal). The numeric reproducibility for each technique was assessed by comparing the normalized differences of each single SAECG parameter between the 2 recordings. Inconsistent results of diagnostic reproducibility were observed in 4.1%, 6.9%, 9.8%, and 18.0%, with TD, STA, ASA, and STM, respectively. Comparisons of these rates were significantly different (P < .05) except between STA and ASA (P = .07). The numeric reproducibility was highest for TD parameters, lowest for STM factors of normality, and intermediate for STA and ASA indices. TD analysis remains the most reproducible SAECG analysis technique, whereas STM showed the worst reproducibility, which limits its clinical applicability. STA and ASA provide an acceptable intermediate reproducibility, the former being slightly, although not significantly, more reproducible than the latter.

Electrocardiography↗
PubMed1998

Comparison of the new acceleration spectrum analysis with other time- and frequency-domain analyses of the signal-averaged electrocardiogram.

AIM: To compare four analysis techniques of the signal-averaged-electrocardiogram, including time-domain, spectral temporal mapping, spectral turbulence analysis and the new acceleration spectrum analysis. METHODS AND RESULTS: We studied 634 subjects (77 with bundle branch block) divided into three groups. Group 1 comprised 117 post-myocardial infarction patients tested for inducibility of sustained ventricular tachycardia, and which was induced in 54 of them. Group 2 comprised 407 consecutive acute myocardial infarction survivors, followed for 1 year; 29 of them had suffered major arrhythmic events: 15 were cases of sustained ventricular tachycardia, three resuscitated ventricular fibrillation and 11 sudden cardiac death. Group 3 comprised 110 control subjects. The different analysis techniques were compared by their likelihood ratio for the prediction of ventricular tachycardia inducibility (Group 1) or major arrhythmic events (Group 2). The likelihood ratios of spectral-turbulence-analysis, acceleration spectrum analysis, spectral temporal mapping and time-domain were 8.0, 3.3, 1.7, 1.3 in Group 1, and 3.8, 2.1, 1.5, 2.6, in Group 2, while the corresponding false-positive rates in Group 3 (control) were 0.9%, 10.0%, 4.5%, and 3.6%, respectively. CONCLUSION: Spectral turbulence analysis was the most accurate technique for the prediction of either ventricular tachycardia inducibility or major arrhythmic events after myocardial infarction. It also showed the highest specificity among control subjects.

Aged↗
PubMed1996

Can the use of growth hormone reduce the postoperative fatigue syndrome?

Convalescence after surgery is characterized by a period of fatigue (POF). If we assume that the POF syndrome has a multifactorial etiology, it is clear that the aim of therapeutic measures should be to reduce the response to surgical stress. The purpose of the present study was to determine if administering exogenous human growth hormone (hGH) can prevent the development or reduce the duration of the POF. We carried out a placebo-controlled randomized double-blind trial with 48 patients after elective cholecystectomy (placebo, or control group, n = 26; hGH-treated group, n = 22). Eligibility criteria were strict so as to introduce as few variables as possible. The results obtained in the study show that for moderate surgical injury (cholecystectomy in metabolically healthy subjects) the administering of low doses of hGH (8 IU/day) minimized the POF syndrome (Christensen score). Furthermore, a positive nitrogen balance was achieved in the hGH-treated group during the postoperative period from the first 24 hours onward. This finding correlates with the significant increase in serum levels of hGH (p < 0.05) and insulin-like growth factor 1 (IGF-1) (p < 0.001). On the other hand, anthropometric measurements in the hGH-treated group revealed a slight but continuous decrease in body weight and thickness of the triceps skinfold; however, arm muscle circumference did not significantly change during the postoperative period. These findings are related to the effects of the application of exogenous growth hormone, which preserves or increases lean body mass and reduces adipose tissue mass. The serum transferrin level proved to be a reliable biochemical indicator of POF.

Adult↗
PubMed1996

[Effects of 3 insecticide formulations in the removal and hatching of oothecae of Blatella germanica (Dictyoptera: Blattellidae)].

Different insecticide formulations used for the control of German Cockroach, Blatella germanica (L.) were studied to know their effects on the gravid females of this species. The insecticides assayed were baygon 20% EC, diazinon 60 EC, and licon 2.5% EC. Exposure to each insecticide showed an effect on the oothecal drop (p < 0.001). Gravid females treated with baygon had the highest percent of oothecae detached (71%); whereas diazinon caused the lowest percent (33.5%). Doses of baygon, diazinon, and icon used showed that among the oothecas detached hatching occurred only in 19.01%; 34.2% and 39.11%, respectively. Of the oothecas retained by treated females, the lowest hatching percent was produced by baygon (13.79%) compared with diazinon and icon insecticides, which presented the highest hatching percentages with 39.84 and 47.82, respectively. Therefore, the effects of insecticides on females bearing oothecas may be considered at the time of selecting an insecticide to control the German cockroach.

Animals↗
PubMed1992

Effects of growth hormone in patients receiving total parenteral nutrition following major gastrointestinal surgery.

The purpose of the present study was to determine whether the administration of a biosynthetic human growth hormone was capable of enhancing the efficacy of total parenteral nutrition. Patients (n = 38) who had undergone major gastrointestinal surgery were randomly divided into two groups. Group I (n = 20) treated only with PN, and Group II (n = 18) treated as in Group I plus human growth hormone (4 IU daily). Our study shows that the administration of human growth hormone produces a statistically significant increase in serum levels of growth hormone, somatomedin-C, transferrin, albumin and total proteins. It also causes a positive nitrogen balance from the first 24 hours onward. These findings suggest that the administration of human growth hormone produces an increase in protein synthesis, perhaps through somatomedin-C as mediator.

Adult↗
PubMed1992

[Effect of growth hormone and parenteral nutrition on the catabolic phase following major digestive surgery].

The purpose of the present study was to determine if the administration of a biosynthetic human growth hormone (bGH) was able to enhance the efficacy of total parenteral nutrition (PN). Patients (n = 38) who had undergone major gastrointestinal surgery were randomly divided in two groups. Group I (n = 20) treated only with PN and Group II (n = 18) treated as in Group I plus bGH (4 UI/daily). Our study shows that the administration of bGH produces a significant increase in serum levels of growth hormone and Somatomedin-C. It also caused a positive nitrogen balance from the first 24 hours on (p less than 0.01). In Group II on day 12 after operation a statistically significant increase in transferrin (p less than 0.05), albumin (p less than 0.01) and total proteins (p less than 0.02) was observed. Our study suggest that the administration of bGH produces, perhaps through Somatomedin-C as mediator, an increase in protein synthesis.

Adult↗
PubMed1991

Efficacy of oral streptokinase-streptodornase in the treatment of ankle sprains.

To evaluate the analgesic and antiinflammatory properties of oral streptokinase-streptodornase (SS) in cases of minor trauma, 190 patients with ankle sprains were studied. Subjects were randomly given an active drug or a placebo in doses of two tablets three times a day for eight days. A scoring system was used to rate the following symptoms: spontaneous pain, mobilization pain, wearing pain, articular disability, flaccidity, muscular spasm, edema, and hematoma. Each symptom was categorized as none (0), mild (1), moderate (3), or severe (4). Patients were evaluated at the beginning of the study and on the fourth and eighth days of treatment. At the end of the trial, the decrease in each symptom score was significantly greater in patients receiving SS than in patients receiving a placebo. Analgesic intake during the study was also noticeably lower in the SS group. The incidence of drug-induced side effects (mainly abdominal discomfort) was minimal. Oral SS ameliorates the inflammatory symptoms associated with ankle sprains and therefore may be used as an alternative to nonsteroidal antiinflammatory drugs.

Adolescent↗
PubMed1990

[Intraoperative autotransfusion in massive hemorrhage following thoracic-abdominal trauma].

In the University Hospital of Granada (Spain), 359 surgical trauma patients underwent intraoperative autotransfusion. The patients were divided into 2 groups, according to their blood loss: group I (blood loss less than or equal to 2000 ml) and group II (blood loss greater than 2000 ml). Patients from group I did not require homologous blood transfusion. So the high risk involved in this type of transfusion was avoided. Macroscopic haemoglobinuria was only found in those patients where the Solcotrans, Viavae type of autotransfusion system was used; with the Bentley ATS system, no macroscopic haemoglobinuria was registered. With patients from group II, however, that is, those with a blood loss of more than 2000 ml, we had to fall back on homologous transfusion in addition to retransfusing autologous blood. When the transfusion exceeds 4000 ml there is increasing bleeding, which requires treatment with fresh frozen plasma, platelets and/or fibrinogen. The mortality rate of patients in group II was very high but the patients died from the severity of their injuries or from postoperative complications which were not due to autotransfusion in itself with the exception of 3 patients who underwent massive autotransfusion (12,000 to 25,000 ml) and died from acute renal failure. The main indication for intraoperative autotransfusion is without doubt abdominal and thoracic trauma which lead to high blood loss.

Abdominal Injuries↗
PubMed1990

[Intraoperative autotransfusion in massive hemorrhage after thoracic-abdominal trauma].

In the University Hospital of Granada (Spain), 359 trauma surgical patients underwent intraoperative autotransfusion. Patients from group I (blood loss less than 2000 ml) did not requiere homologous blood transfusion. So the high risk involved in the type of transfusion was avoided. With patients from group II, however, that is, those with a blood loss of more than 2000 ml, we had to fall back on homologous transfusion in addition to retransfusing autologous blood. The main indication for intraoperative autotransfusion is without doubt abdominal and thoracic trauma which lead to high blood loss.

Abdominal Injuries↗
PubMed1990

[Cross-stimulation in endocardiac AV sequential demand DVI pacemaker associated with great dilatation of the right atrial appendage].

We report on a case of ventricular stimulation by an atrial electrode in endocardiac DVI sequential pacemaker implanted in a patient with cardiomegaly and great atrial appendage. The appropriately placement of the electrode was confirmed by open-heart surgery in the valve replacement. This rare malfunction could be exceptionally studied anatomically.

Aged↗
PubMed1989

Evaluation of toupet antireflux operation, by means of gastroesophageal scintiscan.

The Toupet operation (270 degrees posterior fundoplication) has been performed in 99 patients suffering from symptoms of gastro-oesophageal reflux secondary to a hiatal hernia. To assess the effects of the Toupet antireflux procedure, we performed in 20 cases oesophageal manometry, intraoperatively and gastro-oesophageal scintiscan in the early postoperative period (3 months: 98 cases) and also later (5 years). For us gastro-oesophageal scintiscan is the ideal method of detecting reflux because it is a noninvasive technique as sensitive as the intra-oesophageal pH, is easy to perform and well-tolerated by the patient. Our long-term follow-up, with only 6% of poor results show that the Toupet operation like the Nissen fundoplication is the most effective surgical technique that can be used to correct gastro-oesophageal reflux and has an added advantage: the side effects, particularly the postfundoplication or gas-bloat syndrome are minimal. Additional follow-up after 10 years will be needed to establish the final outcome of the operation.

Adult↗