Biomedical subjects
Publications and source records attributed to O Herrera.
Experimental kinetic data on soap froth cell growth in a random array of fixed pinning centers is reported. The scaling of our two-dimensional data is analyzed and compared with pinning-free growth. The obtained data agree fairly well with a proposed cell growth law. We also discuss the relationship between the pin concentration and the final cell size.
Histological changes in and around the arterial walls of rats were investigated following topical application of aneurysmal wrapping and coating materials, including a fibrin glue, a cyanoacrylate glue (Biobond), and cotton fibers (Bemsheet). Bilateral common carotid arteries were exposed using sterile techniques, and one of the test materials was applied to the right artery. The left artery was used as the control. Changes in arterial histology were evaluated at 2 weeks, 1 month, 2 months, and 3 months after surgery. The fibrin glue was surrounded by intense inflammation at 2 weeks after surgery. Both the fibrin glue and inflammation had disappeared at 2 months, but the glue had induced mild inflammation in the adventitia. Biobond caused chronic inflammation, necrosis of the media, and thickening of the arterial wall due to fibrosis in both the media and adventitia. Bemsheet produced chronic inflammation, progressive fibrosis, and granuloma. Connective tissue increased in the adventitia, but no major changes were observed in the media. The Bemsheet fibers remained unchanged, and adhered to the arterial wall. Although arterial stenoses were not observed in the present study, the results suggest that cyanoacrylate glue can cause the arterial occlusive lesions observed following aneurysm surgery.
Of the approximately 18,000 new cases of cancer in Venezuela each year, only half can be treated with surgery and radiation. The remainder must be treated systematically using chemotherapy or biological response modifiers. It has become evident that any drug resistant human tumors express the MDR1 gene, since MDR1 RNA levels are elevated in many cancers that do not respond to chemotherapy. Human mammary carcinomas have multiple oncogene alterations, the most frequently reported being overexpression of the oncogenes c-myc, int-2, neu and c-myb. Thirteen specimens of mammary cancer were obtained by biopsy of untreated patients in stage IIIB. All these patients received three cycles of FAC or CMF-L+GM-CSF after biopsy. In the slot blot analysis of RNA from invasive carcinomas, MDR1 and c-myc transcripts were detectable at a high level in 30% of tumors. Two patients with increased levels of MDR1 before chemotherapy did not respond to the treatment and distant metastasis and death occurred in these patients. Another patient, MDR1-negative before therapy, did not respond to CMF-1 + GM-CSF and showed high levels of MDR1 transcripts in a second biopsy which was obtained during surgery.
We studied the effects of indoprofen on urea and creatinine clearance and on protein loss in 6 patients submitted to intermittent peritoneal dialysis. The patients had no evidence of peritonitis. Dialysis fluid contained indoprofen (50 mg/l) or no drug. Mean protein loss into dialysis solution was 51.2 g without and 44.7 g with indoprofen (NS). Urea clearance was 33.3 and 33.6 ml/min and creatinine clearance 24.7 and 36.0 ml/min, respectively (NS). Levels of PGF2 alpha in the dialysate, measured in 2 subjects, were not affected by indoprofen. These results suggest that prostaglandins are not the main factors involved in control of urea and creatinine clearance and protein loss during intermittent peritoneal dialysis.
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PURPOSE: The purpose of this preliminary study has been to demonstrate and investigate the activation patterns of the primary auditory cortex (Heschl's gyrus = HG) using functional magnetic resonance imaging (fMRI). MATERIAL AND METHODS: A 2500 Hz tone stimulus was delivered monoaurally to the right and left ear of 15 normal-hearing right-handed volunteers in 20-second on-off cycles. FMRI data were obtained using a 1.5-Tesla scanner and processed with SPM2. RESULTS: Activated pixels were identified in the transverse temporal gyrus (Heschl's gyrus) of both hemispheres in response to pure tone stimuli using cross-correlation analysis (P < 0.001). Bilateral hemispheric activation was observed in all subjects and there was a trend towards contralateral HG activation to the stimulated ear. CONCLUSION: These results demonstrate directly that fMRI is a new and useful imaging technique to study the complex auditory cortex and it will have potential clinical applications in the next future.
INTRODUCTION AND OBJECTIVE: The endocranial hypertension syndrome is one of the commonest and most feared neurological complications in clinical practice. This encourages its continued study, and is the subject of this review. DEVELOPMENT: Endocranial hypertension is the common pathway for the presentation of many neurological and non neurological disorders. An increase in the volume of one or more intracranial structures causes secondary lesions of the brain and even the death of the patient, although this may frequently be avoided by prompt recognition and suitable action by the doctor involved. General, non specific therapeutic measures should be instituted to achieve a normal endocranial pressure. The clinical presentation and complementary investigations should be correctly interpreted to determine the aetiology of the condition so that specific treatment may be given. Continuous monitoring of the intracranial pressure and other neuromonitorization techniques are essential for correct decisions as to treatment. CONCLUSIONS: Understanding the physiopathology, diagnosis and treatment of the syndrome of endocranial hypertension are still essential in modern medicine. In recent years there have been advances in the use of well known treatments and new drugs have been introduced. Use of the different neuromonitoring techniques permits optimum use of the treatment available.