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Biomedical subjects

J A González

Publications and source records attributed to J A González.

At least 19 recordsLinked to original sources
PubMed2006

Cadmium induces changes in sucrose partitioning, invertase activities, and membrane functionality in roots of Rangpur lime (Citrus limonia L. Osbeck).

Cadmium (Cd) uptake effects on sucrose content, invertase activities, and plasma membrane functionality were investigated in Rangpur lime roots ( CITRUS LIMONIA L. Osbeck). Cadmium accumulation was significant in roots but not in shoots and leaves. Cadmium produced significant reduction in roots DW and increment in WC. Leaves and shoots did not show significant differences on both parameters. Sucrose content was higher in control roots than in Cd-exposed ones. Apoplastic sucrose content was much higher in Cd-exposed roots than in control ones. Cd-exposed roots showed a significant decrease in both cell wall-bound and cytoplasmic (neutral) invertase activities; while the vacuolar isoform did not show any change. Alterations in lipid composition and membrane fluidity of Cd-exposed roots were also observed. In Cd-exposed roots phospholipid and glycolipid contents decreased about 50 %, while sterols content was reduced about 22 %. Proton extrusion was inhibited by Cd. Lipid peroxidation and proton extrusion inhibition were also detected by histochemical analysis. This work's findings demonstrate that Cd affects sucrose partitioning and invertase activities in apoplastic and symplastic regions in Rangpur lime roots as well as the plasma membrane functionality and H (+)-ATPase activity.

Cadmium Chloride↗
PubMed2006

Pinealectomy reduces optic nerve but not intergeniculate leaflet input to the suprachiasmatic nucleus at night.

The suprachiasmatic nucleus (SCN) of the hypothalamus regulates circadian rhythms in mammals. It receives, among others, direct inputs from the retina and from the thalamic intergeniculate leaflet (IGL). The former sends photic signals to the SCN, whereas the latter probably integrates photic and nonphotic information. To characterise these inputs in vivo, extracellular single-unit recordings were made from the SCN of rats under urethane anaesthesia during electrical stimulation of the optic nerve (OptN) or the IGL region. Cell responses were evaluated by creating peri-stimulus time histograms. Because humoral signals such as melatonin might modulate the activity of the SCN in addition to neural inputs, recordings were also made using pinealectomised (Px) rats to test for a possible role of this hormone in regulating inputs to the SCN. A significantly greater number of cells responded to IGL (60 of 90, 67%) than to OptN (35 of 75, 47%) stimulation in intact animals (chi(2) = 5.905, P = 0.015). The same was true when Px animals were tested (IGL, 82 of 131, 63%; OptN, 31 of 111, 28%; chi(2) = 27.637, P < 0.001). In intact animals, the proportion of cells responsive to IGL stimulation during the day and during the night was not significantly different from the proportion responsive in Px animals. The same was true for OptN stimulation during the day. However, during the night, the proportion of cells responsive to OptN stimulation in intact animals was significantly greater than the proportion responsive in Px animals (chi(2) = 7.127, P = 0.008). Our findings suggest that a lack of melatonin modulates OptN but not IGL inputs to the SCN.

Animals↗
PubMed2002

Internal modes of sine-Gordon solitons in the presence of spatiotemporal perturbations.

We investigate the dynamics of the sine-Gordon solitons perturbed by spatiotemporal external forces. We prove the existence of internal (shape) modes of sine-Gordon solitons when they are in the presence of inhomogeneous space-dependent external forces, provided some conditions (for these forces) hold. Additional periodic time-dependent forces can sustain oscillations of the soliton width. We show that, in some cases, the internal mode even can become unstable, causing the soliton to decay into an antisoliton and two solitons. In general, in the presence of spatiotemporal forces the soliton behaves as a deformable (nonrigid) object. A soliton moving in an array of inhomogeneities can also present sustained oscillations of its width. There are very important phenomena (like the soliton-antisoliton collisions) where the existence of internal modes plays a crucial role.

Journal Article↗
PubMed1999

Hemodynamic response to tracheal intubation after vital capacity rapid inhalation induction (VCRII) with different concentrations of sevoflurane.

STUDY OBJECTIVE: To evaluate the blood pressure (BP) and heart rate (HR) response to tracheal intubation after vital capacity rapid inhalation induction (VCRII) with four concentrations of sevoflurane followed by nitrous oxide (N2O) 50% and sevoflurane in concentrations administered by clinical judgment. DESIGN: Prospective, randomized study. SETTING: University teaching hospital. PATIENTS: 60 unpremedicated, ASA physical status I and II adult patients undergoing surgery with general anesthesia. INTERVENTIONS: After fentanyl 3 micrograms/kg, VCRII was accomplished with four concentrations of sevoflurane in O2: Group 1 (n = 15): sevoflurane 3%; Group 2 (n = 15): sevoflurane 4%; Group 3 (n = 15): sevoflurane 5%; and Group 4 (n = 15): sevoflurane 6%. At loss of consciousness, rocuronium 0.6 mg/kg was given, and intubation was performed 90 seconds later. Thereafter, anesthesia continued with N2O 50% and sevoflurane. MEASUREMENTS AND MAIN RESULTS: BP and HR measurements were made at the ward (baseline), at loss of consciousness, and just prior to, and each minute after, tracheal intubation during a 5-minute period. The hemodynamic profile among groups was similar, with a slight hypertensive and tachycardic response to intubation. CONCLUSION: VCRII with sevoflurane 3% to 6% following fentanyl 3 micrograms/kg can be considered for blunting the hemodynamic response to tracheal intubation in healthy patients.

Adult↗
PubMed1999

Soliton tunneling with sub-barrier kinetic energies.

We investigate (theoretically and numerically) the dynamics of a soliton moving in an asymmetrical potential well with a finite barrier. For large values of the width of the well, the width of the barrier, and/or the height of the barrier, the soliton behaves classically. On the other hand, we obtain the conditions for the existence of soliton tunneling with sub-barrier kinetic energies. We apply these results to the study of soliton propagation in disordered systems.

Journal Article↗
PubMed1999

[Use of dual-chamber pacemaker. Short and long-term results].

BACKGROUND: Continuous improvement of dual chamber DDD pacemakers, electrode stability and programmed sequential stimulation changed the prognosis of patients implanted with these devices. AIM: To report our experience with the use of dual chamber pacemakers. MATERIAL AND METHODS: One hundred seventy six patients (116 male), aged 13 to 91 years old, who received a dual chamber pacemaker implant, are reported. Patients were followed for a mean of 2.6 years. RESULTS: Indications for DDD pacemaker were complete atrioventricular block in 43%, sick sinus syndrome in 32%, paroxysmal A-V block in 24%. All pacemakers were Siemens-Pacesetter and were provided with an automatic sensing and threshold device. J shaped atrium electrodes were used in 78% of patients and screw-in electrodes in 22%. Post operative complications were displacement of atrial electrode in 8 patients, of ventricular electrode in 6 patients, infection in two patients and a hematoma in one. Chronic parameters, measured after six months, were within expected ranges and allowed a good reprogramming of pacemakers. Long term programming aimed to reduce battery depletion, enhance device performance and improve hemodynamic conditions. Normal sequential stimulation was achieved in 154 patients (87%), 14 (85) patients died of cardiovascular disease not related to pacemaker function. Eight patients were in atrial fibrillation and were reprogrammed to VVI and DDI modes. CONCLUSIONS: DDD pacemakers are reliable and afford symptomatic relief in a broad spectrum of patients.

Adolescent↗
PubMed1998

[Occult rupture of the aortic arch caused by a traffic accident].

A patient presented to our emergency department from another hospital diagnosed with pelvic fracture after a motor vehicle accident. In the ensuing 12 hours, chest pain developed, and a widened mediastinum on chest radiography was found. Posterior aortography showed aortic arch rupture. During surgery, we found a complete circumferential disruption of the arch between the brachiocephalic trunk and the carotid artery. Even though thoracic aortic injuries rarely occur in motor vehicle accidents, thoracic arch ruptures are extremely uncommon. This injury should be suspected after high-speed motor vehicle accidents, when accompanied with chest pain or widened mediastinum.

Accidents, Traffic↗
PubMed1998

[Patent foramen ovale as a cause of recurrent cerebral embolism. Closure with minimally invasive surgery].

We report a clinical case of a 63-year-old patient, referred with a history of repeated strokes, whose only cause was a patent foramen ovale with shunt right to left diagnosed by transesophageal echocardiography. He underwent minimally invasive surgery, through right parasternal minithoracotomy, practising defect closure. We comment on the value of echocardiography for diagnosing this pathology and the utility of this surgical technique for repairing these defects.

Cardiac Surgical Procedures↗
PubMed1998

[Is crystalloid cardioplegia still a valid technique for myocardial myocardial protection?].

OBJECTIVES: The routine use of a cardioplegic solution for myocardial protection during the ischemic phase of cardiac surgery represents a great therapeutic advance. Two cardioplegic solutions are currently in use: crystalloid and blood solutions. As blood cardioplegia has been shown to offer superior myocardial protection, its use at present is widespread. We did a retrospective study to assess whether crystalloid cardioplegia might nevertheless continue to be useful. PATIENTS AND METHODS: Forty patients with heart disease underwent surgery between March 1994 and March 1995, with the use of crystalloid cardioplegia (group A). Blood cardioplegia was used in 72 patients during the same period (group B). RESULTS: There were no significant differences in clinical (age, arterial hypertension, diabetes, chronic bronchial disease, severity of angina, severity of heart disease) or surgical (emergency, percent use of the internal thoracic artery, duration of extracorporeal circulation) variables. The percentage of patients with low ejection fraction was higher in group B as a result of preoperative selection. The mean number of grafts was higher in group B than in group A (3.5% and 2.5, respectively) (p < 0.01). Postoperative results (use of inotropics, counterpulsation balloon, creatine phosphokinase, perioperative myocardial infarction or hospital mortality) were not significantly different. The percent of supraventricular arrhythmias after surgery was higher in group A than in group B (20% and 5%, respectively) (p < 0.05) and lactic dehydrogenase level was lower in group A than in group B (472 and 572 mu/l, respectively) (p < 0.05). CONCLUSIONS: We believe that crystalloid cardioplegia continues to be a valid and effective myocardial protection technique in heart patients with preserved left ventricular systolic function.

Cardiomyopathies↗
PubMed1995

Molecular stereochemistry of [FeIII(TPP)(OCOCF3)].

(meso-Tetraphenylporphinato)(trifluoroacetato)iron(III), [Fe(C2F3O2)(C44H28N4)], consists of a central Fe atom equatorially coordinated to four pyrrole N atoms and axially coordinated th an O atom of the trifluoroacetate group. The average Fe--N bond distance is 2.054(5)A and the Fe atom is displaced 0.483 (1) A from the porphinato plane. The Fe--O distance is 1.921 (4) A. The out-of-plane displacement and the Fe--N bond lengths indicate that the Fe atom is in a high-spin state.

Crystallography, X-Ray↗
PubMed1995

[Tumor necrosis factor-alpha in human immunodeficiency virus infection].

BACKGROUND: The aim of the present was to determine the levels of the tumor necrosis factor (TNF)-alpha in patients with HIV infection to study the relationship with the concentration of triglycerides (TG), CD4 lymphocyte count and clinical diagnosis. METHODS: Seventy-eight HIV-infected patients (58 males, 20 females); mean age 32 years presenting different clinical situations were studied. TNF, TG, CD4 lymphocyte count, and clinical diagnosis at the time of the study were analyzed. RESULTS: The mean TNF values in the sample was 25.5 x 10(-3) pg/l with a confidence interval of 95% (Cl 95%), 16.6 x 10(-3) pg/l to 34.4 x 10(-3) pg/l with a trend to being higher in the group with less than 200 x 10(6) CD4/l (Cl 95%: 18.6 x 10(-3) pg/l-44.3 x 10(-3) pg/l). Mean TG values in the sample were 2.02 milligrams (Cl 95%: 1.72 milligrams-2.31 milligrams) being significantly higher in the group with less than 200 x 10(6) CD4/l (X = 2.35 +/- 1.32 milligrams; p < 0.005). TNF concentrations were found to be significantly higher in the group with acute infection (Cl 95%: 27 x 10(-3) pg/l-69 x 10(-3) pg/l) with respect to the group without infection at the time of the study (Cl 95% 7 x 10(-3) pg/l-19 x 10(-3) pg/l). The correlation coefficient between TNF and TG was r = 0.34 (p = 0.01). CONCLUSIONS: Both the tumor necrosis factor and triglycerides are high in patients with HIV infection and CD4 lower than 200 x 10(6)/l. The correlation between tumor necrosis factor and triglyceride concentrations is positive and significant. The increase in the former is more important when there is concomitant infection and could be considered as a marker of opportunistic infection.

AIDS-Related Opportunistic Infections↗
PubMed1995

Biological activity of secondary metabolites from Bupleurum salicifolium (Umbelliferae).

Secondary metabolites from Bupleurum salicifolium were tested against viruses, Gram-positive and Gram-negative bacteria, the yeast Candida albicans, the nematodes Globodera pallida and G. rostochiensis, the insect Spodoptera littoralis and the crustacean Artemia salina. These compounds were also tested against tumoral and non-tumoral cell lines. The polyacetylene 8S-heptadeca-2(Z)-9(Z)-diene-4,6-diyne-1,8-diol exhibited toxicity for A. salina and specific antibiotic activity against Gram-positive bacteria. Nine of the lignans and one coumarin showed toxicity for A. salina, and the lignans bursehernin and matairesinol inhibited the hatching of the two nematode species. These are the first lignans that have been reported as affecting phytoparasitic nematodes, and the first natural products known to have an effect on the hatching of G. pallida. Lignans may play a role in the defence mechanisms of potato plants, as allelopathic substances acting against cyst-forming nematodes.

Animals↗
PubMed1992

Therapeutic effects of hidrosmin on chronic venous insufficiency of the lower limbs.

A double-blind, placebo-controlled trial was carried out to assess the effectiveness of a new synthetic bioflavonoid, hidrosmin, in patients with chronic venous insufficiency of the lower limbs. Fifty-seven patients, showing varicose veins and ankle swelling and suffering from local pain and heaviness of the legs, were allocated at random to receive treatment for 45 days with 1 capsule 3-times daily of either 200 mg hidrosmin (30 patients) or placebo (27 patients). Pain and heavy legs were assessed using rating scales; swelling was assessed by a photographic method. The results showed that hidrosmin produced a significant clinical improvement in all of the parameters evaluated; compared with placebo, there was a marked reduction in the main subjective symptoms accompanied by a 10% reduction in swelling. Apart from 1 patient who complained of epigastric pain, there were no reports of adverse events during the study period.

Adult↗