Biomedical subjects

R Orellana

Publications and source records attributed to R Orellana.

5 recordsLinked to original sources

PubMed2006

[Allopurinol-induced chronic granulomatous interstitial nephritis].

Although drug induced interstitial nephritis is a relatively common cause of renal failure,granulomatous forms remain a rare condition. The development of a chronic granulomatous interstitial nephritis due to allopurinol is exceptional, only three cases have been described previously. We report on a patient who presented a granulomatous interstitial nephritis after 10 years of allopurinol administration (300 mg/day). At diagnosis, he had end stage renal disease and dialysis treatment was needed. Two months after drug withdrawal and on corticoid treatment a slow recovery of renal function was observed, allowing the interruption of dialysis. Two years after, the creatinine clearance is 23 ml/min,being dialysis free. We discuss the differential diagnosis of granulomatous interstitial nephritis and its rare association with allopurinol treatment.

Adrenal Cortex Hormones↗

PubMed2005

Effects of chronic hypobaric hypoxia on testis histology and round spermatid oxidative metabolism.

In order to evaluate the effects of the exposition to continuous chronic hypobaric hypoxia (CCHH) and intermittent chronic hypobaric hypoxia (ICHH) on testis histology and on oxidative metabolism of spermatogenic cells (SC), male rats were exposed to a 4600-m simulated altitude (PO2: 89.6 mmHg). After 60 days, ICHH and CCHH groups presented a significant decrease in testicular mass, an increase in interstitial space, a decrease in height of the seminiferous epithelium, depletion of cellular elements, vacuolization in epithelial cells and folding of the basal membrane. Round spermatids from animals exposed to CCHH presented a significant decrease in energy-dependent cell shape changes. Round spermatid mitochondria of CCHH rats seem to be limited in their ability to handle reducing equivalents. These mitochondria also appear to be uncoupled under basal conditions. Round spermatids from CCHH rats evidence large oxygen consumption (QO2) insensitive to inhibition by cyanide, a process that could be partly related to lipoperoxidation. Thus, exposure of male rats to CCHH and ICHH induced evident changes in testicular morphology and loss of spermatogenic cells, in all stages of the spermatogenic cycle. This post-meiotic spermatogenic cell loss in the testis correlated well with metabolic changes in round spermatids that evidenced a strong metabolic stress in these cells.

Animals↗

PubMed2005

[Diagnosis and prognosis of atheroembolic disease].

Atheroembolic disease is recognized as an iatrogenic complication from an invasive vascular procedure, such as manipulation of the aorta during angiography or vascular surgery, and after anticoagulant and fibrinolytic therapy. Cholesterol crystal embolism is caused by showers of cholesterol crystals from an atherosclerotic aorta that occlude small arteries. The kidney is a frequent target organ for cholesterol emboli because of proximity of the renal arteries to abdominal aorta and it receive an enormous amount of blood flows. We describe the epidemiologic agents of 19 cases that were diagnosed by histologic sections of the affected tissues; the eosinophilia and the renal failure are the clinical features that guide to the diagnosis, in patients with ischemic nephropathy and general atherosclerosis. 53% among patients had a previous invasive procedure and 26% occurred spontaneously. We remark the importance of the kidney's biopsy in diagnosis of the atheroembolic disease and their bad prognosis with 63% of death rate in 18 months of average follow-up. We report patients with the multiple cholesterol emboli syndrome mimicking systemic vasculitis: they died by multivisceral acute failure. The subacute presentation of atheroembolic disease with progressive renal failure treated with hemodialysis is a sign of bad prognosis. The knowledge of the disease and their prevention are the better treatment.

Adult↗

PubMed2000

Short-term bioeffects of an infrared pulsed laser device on burned rat skin monitored by transverse relaxation times (NMR).

BACKGROUND AND OBJECTIVE: The aim of this study was to determine whether the application of an infrared pulsed laser device (IPLD) on the burned skin of rats induced significant changes in the water dynamics of the burned tissues as measured by nuclear magnetic resonance (NMR) at a proton frequency of 90 MHz by using transverse relaxation times (T2, I/T2). STUDY DESIGN/MATERIALS AND METHODS: Seven groups (GI-GVII), each consisting of four albino rats (Sprague-Dawley), of 12-14 weeks of age were used in the experiment. Rats in GI-GVI were anesthetized and burned with a hot tip. GI, GIII, GV were not irradiated. GII, GIV, GVI were irradiated at 0 hours; 0 and 24 hours; and 0, 24, and 48 hours, respectively. Rats in GVII served as controls and were neither burned nor irradiated. Samples from all groups were obtained and monitored by NMR by using transverse relaxation times (T2 and 1/T2). An unpaired Student's t-test and a one-way analysis of variance (ANOVA I) were preformed on the mean values obtained (T2, 1/T2). The statistical design was chosen to give a 95% power of contrast 1-beta (1/T2). The modulated beam of the IPLD used is composed of two superposed waves; a carrier wave (3 MHz), and a drive force wave in the near infrared (904 nm, f = 1014 Hz). A dose of 1.5 x 10(3) J/M2 per session was applied by placing the IPLD directly over the burned tissue by using a top-hat distribution. RESULTS: The results of a t-test on the T2 and 1/T2 values did not show statistically significant differences at 0 and 24 hours between the irradiated groups, the nonirradiated groups, and the nonburned nonirradiated (control) group. Nonetheless, at 48 hours after the burn, we found a statistically significant difference in the 1/T2 values for the irradiated specimens compared with the nonirradiated specimens and the control group. Furthermore, the variance of the 1/T2 values as a function of time showed a tendency to decrease significantly only for the irradiated specimens. CONCLUSION: These findings show possible effects on the water dynamics of burned rat tissue in a short term as a result of the IPLD's application.

Animals↗

PubMed1986

[Digital image processing: fundamental techniques and applications in biological research].

Digital image processing represents a relatively new but very dynamic domain. Its importance is still growing due to the rapid development in related computer equipment. In this paper basics concepts are introduced and a survey of problems and methods is presented. Starting with techniques used for the capture of data, it continues with techniques applied to coding new data, image enhancement and pattern recognition. Special attention is given to pattern recognition techniques which provide the basics for classification of data according to established criteria. Finally, two applications are presented; the reconstruction of 3-D volumes from serial cutting and a survey of chlorophyll concentration on Lake Aculeo using remote images obtained by the LANDSAT satellite.

Analog-Digital Conversion↗