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Biomedical subjects

O Rojas

Publications and source records attributed to O Rojas.

18 recordsLinked to original sources
PubMed2006

Anaerobic treatment of cassava starch extraction wastewater using a horizontal flow filter with bamboo as support.

Small-scale sour starch agroindustry in Colombia suffer from absence of water treatment. Although starch processing plants produce diluted wastewater, it is a source of pollution and cause environmental problems to the nearby rural population. A laboratory scale anaerobic horizontal flow filter packed with bamboo pieces was evaluated for the treatment of cassava starch extraction wastewater. The wastewater used in the experimentation was the draining water of the starch sedimentation basin. The reactor was operated for 6 months. It was inoculated with a semi-granular sludge from an anaerobic UASB reactor of a slaughterhouse. Maximum organic loading rate (OLR) applied was 11.8g COD/L d without dilution of the wastewater. At steady state and maximum OLR applied, 87% of the COD was removed and a gas productivity of 3.7L/L d was achieved. The average biogas yield was 0.36L/g COD removed. Methane content in the biogas was in the range of 69-81%. The total suspended solids (TSS) removed were 67%. The relative high lactic acid content did not negatively influence the performance of the reactor. No perturbation due to cyanide (3-5mg/L) was observed during the reactor operation. The results obtained indicated that the anaerobic horizontal flow filter could be used efficiently for the treatment of wastewater from Colombian starch processing small-scale agroindustry.

Bacteria, Anaerobic↗
PubMed2005

Active spleno-femoral shunt avoids splanchnic congestion during portal triad occlusion: an experimental study.

UNLABELLED: Portal triad occlusion (PTO) is often performed during hepatic resections for trauma or malignancies to minimize intraoperative blood loss. The pringle maneuver is also regularly required during liver transplantation. This maneuver leads to temporary hepatic ischemia and may be associated with splanchnic blood flow congestion, promoting undesirable hemodynamic disturbances in some patients. Veno-venous bypass is a useful, easily performed technique that may avoid those deleterious hemodynamic effects of PTO. We tested the hypothesis that an active spleno-femoral shunt maintains hemodynamic stability and promotes complete decompression of the mesenteric bed, avoiding intestinal mucosal blood congestion, during PTO. METHODS: Seven dogs (17.2 +/- 0.9 kg) were subjected to 45 minutes of hepatic ischemia during which there was an active spleno-femoral shunt. Systemic hemodynamics were evaluated through Swan-Ganz and arterial catheters. Splanchnic perfusion was assessed by portal vein blood flow and hepatic artery blood flow (PVBF and HABF, ultrasonic flowprobe), intestinal mucosal-arterial pCO(2) gradient (D(t-a)pCO(2), tonometry), and regional O(2)-derived variables. RESULTS: No significant changes in systemic and regional parameters were observed during the ischemia period. During reperfusion, a significant decrease in mean arterial pressure, PVBF, and arterial pH was observed. A significant increase in ALT and D(t-a)pCO(2) (4.8 +/- 2.5 to 18.9 +/- 3 mm Hg) was also observed following hepatic blood flow restoration. CONCLUSION: Spleno-femoral shunt maintains systemic hemodynamic stability, with an effective decompression of the splanchnic bed during portal triad occlusion. The deleterious hemodynamic and metabolic effects observed during reperfusion period, such as transitory hypotension, high D(t-a)pCO(2), and acidemia, were associated with an isolated hepatic ischemia-reperfusion injury, not with the blood congestion in the splanchnic bed.

Animals↗
PubMed2000

Ethyl-2-cyanoacrylate fixation of the cranial bone flap after craniotomy.

BACKGROUND: This procedure was done in order to evaluate the efficacy and safety of ethylcyanoacrylate as an adhesive for fixation of the bone flap. METHODS: One hundred consecutive craniotomies in patients older than 16 years in which the bone flap was fixed with ethyl-2-cyanoacrylate were studied. The osteosynthesis and any complications in all cases were followed clinically and radiologically for 3 months. RESULTS: Clinical and radiographic observation demonstrated that osteosynthesis was produced in 100% of the cases with no complications related to this procedure. CONCLUSION: This technique proved to be safe, fast, and easy to accomplish, with immediate stability of the bone flap and excellent cosmetic results.

Adhesives↗
PubMed1999

Laparoscopic repair of pleural laceration produced during truncal vagotomy: case report.

A partial pneumothorax developed in a patient undergoing laparoscopic truncal vagotomy when a small pleural laceration was accidentally produced. Changes in oxygen saturation and PETCO2 were immediately detected by the anesthesiologist and measures were taken to maintain the patient's ventilatory stability. The pleural laceration was repaired laparoscopically, and the pneumothorax was corrected by ventilatory manipulation, avoiding the placement of a chest tube. The procedure was completed uneventfully. Literature about the causes of pneumothorax during laparoscopic procedures as well as preventive and therapy viewed.

Aged↗
PubMed1998

[Malignant pleural mesotheliomas].

An increase in incidence of malignant pleural mesotheliomas has been noted recently. In order to assess our own experience, we reviewed all medical records and biopsies of patients who were seen with this diagnosis in Hospital Maria Ferrer between January 1986 and December 1997. Clinical data of 17 patients were analyzed. Mean age was 59 years, 76% were male. Industrial or environmental exposure to asbestos was established in 9 patients (53%). Most common symptoms at presentation were dyspnea (88%) and chest pain (65%). Pleural thickening with or without effusion was the usual finding in chest X rays and CAT scans. Biochemical analysis of pleural fluids was consistent with exudate. Diagnosis was performed by thoracotomy (47%), needle biopsy (23.5%) and videothoracoscopy (29.5%). Histological samples were available for review in 16 of the 17 patients: they were epithelial (10), sarcomatoid (2) and mixed tumors (4). Treatment reflected varying approaches. Palliative methods (pleurodesis, chemotherapy and radiotherapy) were preferred at the beginning while more aggressive interventions are performed nowadays. Pleuroneumonectomy alone or in combination with other therapies was carried out in 5 patients with no operative mortality although some complications occurred such as empyema, bronchopleural fistula and severe chest pain. Survival rate for all groups was 10.5 +/- 5.9 months. However, the mean survival of patients who underwent surgery was 17.5 +/- 2.1 months (p < 0.04) with an associated improvement in quality of life. Therefore, we consider that surgery associated with other therapies offers at present, the best therapeutic option for this bad prognosis condition.

Adult↗
PubMed1997

Implication of beta 1- and beta 2-adrenergic receptors in the antinociceptive effect of tricyclic antidepressants.

Tricyclic antidepressants have been shown to be useful for the treatment of pain of varying etiology. Monoaminergic systems seem to be implicated in this phenomenon. In this study, the influence of the selective beta 1- (CGP 20712A) and beta 2- (ICI 118551) adrenergic blockers on the antinociceptive effect of desipramine and nortriptyline was studied in mice using physical and chemical nociceptive tests that implicate different levels of sensory-motor integration in the central nervous system (CNS). An activity test was performed to detect "false positive" or "false negative" results. Results obtained show that both CGP 20712A and ICI 118551 are able to antagonize the antinociceptive effect of these antidepressants in physical tests (hot-plate and tail-flick). However, in chemical tests (acetic acid and formalin), the analgesic effect of the antidepressants used was only antagonized by CGP 20712A. These results suggest that the analgesic effect of desipramine and nortriptyline is mediated by beta-adrenoceptors. The beta-adrenoceptor involved depends on the type of nociceptive stimulus: beta 1 and beta 2 are both implicated when the stimulus is physical, but only beta 1 is involved when the stimulus is chemical.

Animals↗
PubMed1996

[Tuberculin reactivity in the elderly. Comparison of PPD-RT23 and PPD-CT68].

BACKGROUND: Tuberculin reactivity varies on the basis of the PPD lot and the population studied. AIMS: To compare tuberculin reactivity in the elderly following successive applications of PPD from 2 different lots. POPULATION: Elderly nursing-home residents, from the province of Guadalajara, Spain. METHODS: The elderly were randomly selected and administered with a first Mantoux intradermoreaction of 2 UT of PPD-RT23 or 2 UT of PPD-CT68. The study was performed in a scaled basis, eliminating the reactors (transversal induration > or = 5 mm at 72 h). The non reactors were restudied with a second and third test in alternative arms at a 7-day interval with the same lot and initial dosis of PPD. At one year the scaled study was repeated with 2 UT of PPD-CT68. RESULTS: Eight hundred and thirty elderly persons (79 +/- 9 years) were studied, with 410 receiving PPD-RT23 and 420 receiving PPD-CT68. No differences were observed in the percentage of initial reactors (31% vs 29%; p = 0.26) or in the booster reactors (23% vs 20%; p = 0.16). The PPD-RT23 was found to trigger more intensive reactions than the PPD-CT68 leading to a greater frequency of indurations > 14 mm. After one year, the percentage of stable reactions was similar in both groups (50.5% vs 49.5%; NS). CONCLUSIONS: 1) In elderly nursing-home residents 2 UT of PPD-RT23 and 2 UT of PPD-CT68 showed similar results in regard to the number of reactors and the frequency of booster reactions. 2) The proportion of intense reactions was greater with 2 UT of PPD-RT23 than with 2 UT of PPD-CT68. 3) The stability of the reactions at one year was independent of the lot used in the first phase.

Aged↗
PubMed1994

[Rounded atelectasis: another pulmonary pseudotumor].

Rounded atelectasis or Blesovsky's syndrome (also called pleuroma, folded lung or shrinking pleuritis with atelectasis) is the association of plaque-like pleural fibrosis with a folding visceral pleura and nodular atelectasis of the underlying lung. It can mimic a peripheral lung tumor or a mesothelioma. Radiography and computed tomography (CT) show a characteristic opacity with a comet-tail sign. The pathogenesis in some of the cases is considered to be secondary to pleural effusions and in others to a contraction of a focus of pleural fibrosis, not associated with effusion. In many cases, there was a history of asbestos exposure. We report the case of a 44-year-old, man who had smoked and worked with materials containing asbestos. He referred thoracic pain of 6 months duration and dyspnea. An X-ray of the chest (Fig. 1, 2) and a CT scan (Fig. 3) revealed a round peripheral mass in the left lower lobe. A fine needle aspiration biopsy of the lung was performed revealing clusters of large atypical cells with abundant cytoplasm. A thoracotomy was decided upon and no frozen section was requested. Gross examination of the resected lobe (Fig. 4) demonstrated a 2.5 cm white, irregular, firm and retracting pleural plaque. On sectioning, a peculiar folding of the visceral pleura delimited by anthracotic pigmentation was noted below the fibrotic plaque. The folding extended perpendicularly deep into the parenchyma. It was possible to separate the folding and liberate the underlying parenchyma, which was firm, fibrotic and atelectatic. No tumor was found anywhere within the lobe.(ABSTRACT TRUNCATED AT 250 WORDS)

Biopsy, Needle↗
PubMed1982

[Biomedical aspects of 4 cases of snake bites by Lachesis muta (Ophidia: Viperidae) in Costa Rica].

Three out of four cases of snake bite by Lachesis muta stenophrys (Bushmaster) in Costa Rica were fatal and one recovered after a long period of hospitalization. Initial symptoms were similar to those of bothropic envenomation: intense pain, nausea, vomiting, sweating, and excitability, but differing in the magnitude of a tremendous edema and in the absence of intensive bleeding and phlyctenae. We found important alterations in arterial blood pressure and in the activity and concentration of coagulation factors. All patients showed infections, and necrosis was found in at least three of them.

Antivenins↗
PubMed1977

Replacement of the trachea with dura mater. Experimental work.

Results in a series of 30 dogs subjected to tracheal resection and repair are described. The dogs were divided into three groups. Seven to ten rings of the trachea were resected and then were replaced by a prosthesis made of dura mater and stainless steel wire. Different aspects of the procedures for respiratory support in the three groups are evaluated, as are the different kinds of prostheses used. Our results with ventilatory studies showed taht the mose effective means of respiratory support was insertion of an endotracheal tube after thoracotomy. Among the prostheses, the one used in the third group of dogs, a stainless steel spring covered with only one layer of dura mater, allowed a longer survival period but eventually caused late scarring and stenosis.

Animals↗
PubMedDate not supplied

[Usefulness of the PCR technique (polymerase chain reaction) in the follow-up of patients infected with hepatitis C virus. Preliminary communication].

UNLABELLED: In the study we show the usefulness of PCR (polymerase chain reaction) to follow patients with chronic hepatitis, infected with hepatitis C virus (HCV) of Centro Médico de Caracas. The study included 14 patients: 12 anti-HCV positive, 1 with chronic autoimmune hepatitis and 1 classified as non B-non C hepatitis. The patients were divided in 3 groups: Group 1 (5 pretreatment patients, anti-HCV+), 4 with increase in ALT and PCR positive, 1 with normal ALT and PCR negative. Group 2 (7 treated with recombinant interferon alpha 2b), 4 without normalization of ALT and PCR positive, 3 with normalization of ALT and PCR negative. Group 3 (control) 2 patients anti-HCV negative and PCR negative. Two posttreatment patients could be genotyped: one patient was infected with 1a and showed an early relapse with treatment and the other was infected with genotype 1b, which is reported to be more refractory to antiviral treatment. CONCLUSIONS: the results show a 100% correlation between biochemical markers of HCV infected patients and the presence of viral RNA detected by PCR. the usefulness of determination of genotype to assess any prognostic value of this parameter in Venezuela is discussed.

Follow-Up Studies↗