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Biomedical subjects

J González-García

Publications and source records attributed to J González-García.

At least 19 recordsLinked to original sources
PubMed2006

Optimisation of 20 kHz sonoreactor geometry on the basis of numerical simulation of local ultrasonic intensity and qualitative comparison with experimental results.

The intensity distribution of the ultrasonic energy is, after the frequency, the most significant parameter to characterize ultrasonic fields in any sonochemical experiment. Whereas in the case of low intensity ultrasound the measurement of intensity and its distribution is well solved, in the case of high intensity (when cavitation takes place) the measurement is much more complicated. That is why the predicting the acoustic pressure distribution within the cell is desirable. A numerical solution of the wave equation gave the distribution of intensity within the cell. The calculations together with experimental verification have shown that the whole reactor behaves like a resonator and the energy distribution depends strongly on its shape. The agreement between computational simulations and experiments allowed optimisation of the shape of the sonochemical reactor. The optimal geometry resulted in a strong increase in intensity along a large part of the cell. The advantages of such optimised geometry are (i) the ultrasonic power necessary for obtaining cavitation is low; (ii) low power delivered to the system results in only weak heating, consequently, no cooling is necessary and (iii) the "active volume" is large, i.e. the fraction of the reactor volume with high intensity is large and is not limited to a vicinity close to the horn tip.

Computer Simulation↗
PubMed2005

Characterization of a 20 kHz sonoreactor. Part II: analysis of chemical effects by classical and electrochemical methods.

A new electrochemical redox probe has been investigated in order to characterize the local production of radicals during the cavitation events. The results have been compared with those obtained with Fe(CN)6(3-)/Fe(CN)6(4-) (electrochemical probe for local mechanical effects) and classical chemical methods such as iodide and Fricke dosimeters (chemical probes for global effects).

Aluminum↗
PubMed2005

Characterization of a 20 kHz sonoreactor. Part I: analysis of mechanical effects by classical and numerical methods.

Numerical simulations have been carried out in order to characterize the ultrasonic field propagation and to obtain the spatial distribution of the mechanical effect derived from it. The results have been compared with those obtained with different classical physical methods (calorimetry, aluminium foil erosion, thermal probes) and have given useful information about the influence of the presence of probes and auxiliary tools in the ultrasonic field. All these information have been used for the development of the Part II of this work: analysis of chemical effects, providing an accurate picture of the reaction environment in the sonoreactor used (20 kHz, 100 W supplied by Undatim) for further uses in sonoelectrochemical studies.

Aluminum↗
PubMed2005

[Anti-apoptotic potencial role of p38 in prostate cancer].

INTRODUCTION: TNF-alpha transduction pathway in prostate cancer seems to be diverted towards p38 activation. P38 may protect prostate tumoral cells from TNF-alpha apoptosis induced. The aim of this study was study the role of p38 in vivo (were evaluated some p38 downstream factors), as well as in vitro (in prostatic tumoral cell lines, LNCaP and PC3, pre-treated with TNF-alpha). MATERIAL AND METHODS: Two prostatic tumoral cell lines (LNCaP and PC3) were used in in vitro studies. Two different experiments were made: with TNF-alpha (several concentrations) and p38 specific inhibitor (SB203580). The apoptotic index were evaluated using DAPI staining and flow cytometry. P38 activation was measured by Western blot analysis. 15 normal samples (NP) and 27 prostate cancer samples (PC) were used in in vivo study, all of them were processed for immunohistochemistry and Western-blot. RESULTS: In vitro, TNF-alpha induced apoptosis in LnCap when we increased its concentration but not in PC3. TNF-alpha stimulation led to increase a time-dependent p38 phosphorylation in two intermediate doses whereas in PC3 not changes were found. In LNCaP after its preincubation with SB203580 and TNF-alpha treatment showed a significative increasing of apoptosis. In vivo, all NP samples were found positives to p-Elk-1 and p-ATF-2 (nuclei of epithelial cells). In PC the expression of p-Elk-1 or p-ATF-2 increased and was located in the nucleus and cytoplasm of epithelial cells. CONCLUSION: Our data in vitro and in vivo suggest that p38 plays a very important role in prostatic tumour progression. These data suggest that the control activation of p38 might be a possible target to cancer prostate treatment.

Apoptosis↗
PubMed2005

Comparison between sequence analysis and a line probe assay for testing genotypic resistance of human immunodeficiency virus type 1 to antiretroviral drugs.

The purpose of this study was to compare a line probe assay (LiPA) with sequence analysis for the detection of mutations conferring resistance to nucleoside and non-nucleoside inhibitors in human immunodeficiency reverse transcriptase and protease inhibitors. The limitations for interpreting LiPA make it unacceptable for routine clinical practice.

Anti-HIV Agents↗
PubMed2004

[Spinal epidural empyema. Analysis of 14 cases].

OBJECTIVE: The goal of this study was to review our series of spinal epidural empyema diagnosed in the last 20 years and review the literature regarding the pathogenesis, diagnosis and treatment of these lesions. PATIENTS AND METHODS: This is a retrospective study over 14 patients diagnosed of spinal epidural empyema. We review the epidemiological data, clinical symptoms, laboratory and imaging data, the treatment regimen and the results. RESULTS: Fourteen patients, 7 males and 7 females, with an age range from 8 to 76 years (mean 48.9) were identified. The first symptom was localized back/ neck pain in 12 patients and the mean duration of symptoms was 9.3 days. Erythrocyte sedimentation rate (ESR) was elevated in all patients; peripheral leukocyte count was elevated in 13 cases (92.9%). Site of spinal epidural empyemas was distributed along the axis but in 11 cases the location was thoracic. Thirteen patients had surgery for debridement and spinal decompression and one patient was treated successfully with antibiotics alone. CONCLUSIONS: Patients with localized back pain and fever who are at risk for developing such empyemas with elevation of white blood cells and increased ESR, should have an immediate magnetic resonance imaging sean. Urgent surgical drainage and antibiotic use are the treatment of choice in order to prevent irreversible neurological deficits. Nonsurgical treatment should be reserved for poor surgical candidates and patients without neurological deficits.

Adolescent↗
PubMed2004

[Acute spontaneous subdural haematoma of arterial origin].

INTRODUCTION: An acute subdural hematoma is often regarded as a complication of head trauma. Occasionally subdural bleeding from the rupture of a cerebral aneurysm or an arteriovenous malformations is described. Spontaneous subdural hematoma is, however, very rare and it commonly has an arterial origin and their aetiology is still a matter of controversy. OBJECTIVE: The purpose of this paper is to present eight cases of spontaneous subdural hematoma seen at our department during the last 19 years. The etiological possibilities of spontaneous subdural hematoma are discussed. PATIENTS AND METHODS: We analyzed 8 cases of acute spontaneous subdural hematoma among a total number of 321 patients with subdural hematoma is presented. RESULTS: There were six males and 2 females with a mean age of 52 years (range 20-66). All patients developed progressive neurological deficits, until become comatose. All eight patients were operated on and surgical mortality was 25%. CONCLUSIONS: Spontaneous subdural hematoma is a rare condition and the prognosis is mainly dependent on the pre-operative neurological state regardless of its origin or cause.

Adult↗
PubMed2002

[Epidermoid cyst of the third ventricle].

Intracranial epidermoid tumours are very rare lesions of ectodermal origin that account for 1% of all intracranial tumours. The favourite sites affected by these tumours are the cerebellopontine angle and the chiasmal region. They also appear in the cerebral hemisphere and the intraventricular cavities. We report a case of epidermoid tumour of the third ventricle. The patient was a 68 year-old woman admitted in our service with a 7-days history of headaches and intermittent nausea and vomiting. A CT scan of the brain revealed a large hypodense mass in the third ventricle associated with hydrocephalus. An MRI was performed and revealed, on T1-weighted image, an irregular nonhomogeneous lower signal in relation with CSF. This tumour showed a very bright signal intensity on T2-weighted images. A transcallosal approach of the tumour mass was performed via a right frontal craniotomy. Using an ultrasonic aspirator, the tumour was removed. In a review of the literature, we found only 8 reported cases.

Aged↗
PubMed2001

Influence of chloride ion on electrochemical degradation of phenol in alkaline medium using bismuth doped and pure PbO2 anodes.

Electrochemical method at laboratory scale for the treatment of biorefractory solutions with high phenol content--1000 ppm is described. Total degradation of phenol was obtained at alkaline pH when NaCl was present using Bi-doped and pure lead dioxide electrodes. A filter press cell of 63 cm2 geometric area was used for this purpose. Measurements of chemical oxygen demand (COD), phenol, carbon monoxide, carbon dioxide, and volatile organic compounds (VOCs) have been used to characterise the electrochemical process for phenol elimination. It is worth noting that in the absence of NaCl, the charge efficiency of COD removal was independent of the current density in the range studied (50-100 mA cm(-2)) Moreover, when NaCl was present, the current efficiency for COD and phenol removal increase as the chloride concentration increases. Chloroform was the only halocompound detected at the end of reaction. For both electrodes, Bi-doped and pure lead dioxide, the chloroform concentration at the end of the electrolysis decreases, working at low current densities and for low chloride concentrations.

Anions↗
PubMed2000

[Influence of a day care hospital on the incidence of hospital admission of AIDS patients].

BACKGROUND: Day care units have become an usual way of medical care for AIDS patients. However, their influence on the incidence of hospital admissions has not been evaluated. METHODS: Observational and longitudinal study of a cohort of 308 patients with aids diagnosed between 1990 and 1994 and followed-up to June 1996. The incidence of hospital admissions according to the hospital of follow-up (with or without day care unit) was analyzed. A multivariate analysis of the number of hospital admissions was performed using regression model adjusted to a distribution of Poisson. RESULTS: After AIDS diagnosis, the incidence of hospital admissions was 108 per 100 patient-years of follow up (21 days as inpatient per patient-year). Those patients controlled in the hospital with day care unit have less hospital admissions (relative risk after adjusting by CD4+ cells count and type of diagnostic disease: 0.64; CI95% 0.55-0.76), and less days as inpatient through their follow-up (11 to 31 days less). There was no difference in survival among patients followed in both hospitals. CONCLUSIONS: A day care unit decrease the incidence of hospital admissions in aids patients. This positive impact is more evident in patients with lesser CD4+ cell counts.

Acquired Immunodeficiency Syndrome↗
PubMed1998

[Pneumocystis carinii pneumonia and HIV infection: diagnosis and treatment].

Pneumocystis carinii pneumonia (PCP) is one of the leading complications among HIV-infected patients. Recent advances in PCP prophylaxis, diagnosis and treatment have caused a decrease in PCP-related morbidity and mortality. Despite these advances, PCP continues to be frequent in patients not known to be HIV-infected and in those patients with poor adherence to prophylactic regimens or severe immunosuppression. In typical cases diagnosis may be suspected by the patient's clinical presentation. Clinicians are frequently faced with the differential diagnosis between PCP, bacterial pneumonia, pulmonary tuberculosis, and other specific respiratory disorders HIV-associated. Definitive diagnosis of PCP requires demonstration of Pneumocystis carinii (PC) in respiratory secretions or lung tissue. Conventional techniques, immunofluorescence using monoclonal antibodies and molecular techniques are highly specific, but sensitivity varies depending on the PC load present in the sample. Best diagnostic yield is obtained analyzing samples obtained by bronchoalveolar lavage. PC diagnosis using highly sensitive PCR in sputum-induced samples might allow noninvasive diagnosis in most HIV-infected patients suffering from PCP but PCR techniques remain to be standardized. Like in PCP prophylaxis, trimethoprim-sulphametoxazole (TS) is the drug of choice for PCP treatment. In severe case, TS is given intravenously. If patient is intolerant to TS, i.v. pentamidine or i.v. trimetrexate with folinic acid can be used. TS has a dose-dependent toxicity. In cases of hypersensitivity to TS, drug-desensitization should be tried. In severe documented PCP adjunctive corticosteroid therapy is effective and safe. In mild to moderate PCP, TS can be given orally. Best alternatives to TS in this situation are dapsone-pyrimethamine or clindamycin-primaquine (CP). Other effective options are oral atovaquone, aerosolize pentamidine and i.v. pentamidine.

AIDS-Related Opportunistic Infections↗
PubMed1997

[Intraventricular arachnoid cyst in the adult].

INTRODUCTION: Intracranial arachnoid cysts are benign, congenial cystic lesions found in infancy. The commonest sites are the lateral fissure and the posterior fossa. Exceptionally they may be found in the ventricular system. CLINICAL CASE: We describe a 69 year old patient with a clinical history of headache and tingling of the face for 24 hours. Diagnosis of a lateral ventricle arachnoid cyst was made on computerized tomography and magnetic resonance. Treatment was surgical with excision of the wall of the cyst and the communication with the ventricle. CONCLUSION: We review 14 cases previously described (9 adults and 5 children), analyzing their clinical and radiological features, type of treatment given and the different theories proposed as to pathogenesis.

Adult↗
PubMed1994

Systemic polyarteritis nodosa as the initial manifestation of a gastric adenocarcinoma.

We report a case of systemic polyarteritis nodosa (PAN) leading to the discovery of an as yet asymptomatic, surgically curable gastric adenocarcinoma. PAN is rarely associated with malignancies and in such cases these are more often malignant haematological diseases than solid neoplasms. The immunopathological findings, the temporal relationship between both conditions, and the spontaneous resolution of vasculitis after tumour removal suggest a paraneoplastic origin of the systemic angitis.

Adenocarcinoma↗
PubMedDate not supplied

[Cervical epidural abscess as a cause of tetraparesis].

INTRODUCTION: An epidural spinal abscess is a rare clinical condition which may cause rapid, irreversible neurological deterioration. Usually, the patient presents with back pain in the affected spinal segment, but the condition is rarely considered in the differential diagnosis. CLINICAL CASE: A 57 year old man with no significant clinical history initially consulted complaining of cervicalgia. Some days later, this had worsened and he also had odinophagia, fever and general malaise. A diagnosis of retropharyngeal abscess was made. He was admitted to the Ear, Nose and Throat Department (ENT) and antibiotic treatment started with ceftazidime, vancomycin and clindamycin. Eight hours after admission he complained of paresthesia and subsequently of flaccid tetraparesia. CT and MR showed the presence of a paravertebral mass which extended to the epidural space between the fourth and seventh cervical vertebrae. On suspicion of a retropharyngeal abscess complicated by an epidural spinal abscess we proceeded to emergency operation and drained the prevertebral and epidural pus. On microbiological culture St. aureus was grown. The patient regained the mobility of his limbs. On discharge from hospital he still had paresia of the right leg, although this did not impede walking. CONCLUSIONS: It should not be forgotten that, although rare, one of the causes of spinal compression and neurological deterioration (particularly in a febrile patient) is an epidural spinal abscess. Prompt diagnosis and satisfactory surgical decompression are essential to avoid irreversible neurological sequelae.

Central Nervous System Bacterial Infections↗
PubMedDate not supplied

[Intracranial collections of pus. A review of 100 cases].

INTRODUCTION: In recent decades, important scientific advances have been made, leading to modification of the diagnosis and the treatment of intracranial collections of pus (ICP). OBJECTIVES: To analyze the changes in various clinicopathological aspects of ICP during the twenty years studied. PATIENTS AND METHODS: We present a retrospective analysis of 100 cases of ICP diagnosed between 1979 and 1998 in the Hospital General de Galicia. We divided the patients into two groups: A (1979-1988) and B (1989-1998), and analyzed the similarities and differences between them. RESULTS: In these two decades, there was a predominance of men over women (4/1) ENT infections (30/100) and surgical-trauma (25/100) were the commonest causes. The diagnosis was established during the week the symptoms started in 40% of group A and 58.1% of group B. The most frequent site for abscesses was in the frontal lobes (28.5%) and temporal lobes (26.1%) and was closely related to the origin of the infection. Culture was positive in 45% of group A and in 60.3% of group B. The commonest micro-organisms found were Streptococcus (38%) and Staphylococcus (26%). More anaerobes were observed in the second decade. The most usual surgical treatment was excision (86%). Mortality was 33.3% in the first decade and 5.4% in the second. CONCLUSION: Technological improvements permit earlier, more reliable radiological and micro-biological diagnosis as well as lower morbi-mortality figures for ICP.

Adolescent↗