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Biomedical subjects

A Mosquera

Publications and source records attributed to A Mosquera.

13 recordsLinked to original sources
PubMed2001

Long-term effect of bilateral ovariectomy on endothelial function in aortic rings of spontaneously hypertensive rats: role of nitric oxide.

Endothelial dysfunction associated with both menopause and hypertension could be one of the possible explanations for increased cardiovascular morbidity and mortality in hypertensive postmenopausal women. The aim of the present study was to investigate the long-term effect of menopause (bilateral ovariectomy) on endothelial function in isolated aortic rings of spontaneously hypertensive rats (SHR). Aortic rings were suspended in organ chambers filled with physiological salt solution (95% O2, 5% CO2, 37 degrees C), and isometric tension was measured. In studies designed to assess the tone-related release of nitric oxide (NO) from phenylephrine-precontracted aortic rings, we found that vasoconstriction induced by L-NAME was greater in aortic rings from sham-ovariectomized SHR (SHAM SHR) than in those obtained from ovariectomized SHR (OVX SHR). Concentration-related relaxant responses to superoxide dismutase were significantly greater in the SHAM SHR than in the OVX SHR. In contrast, receptor-mediated release of NO was not altered by ovariectomy, as deduced from acetylcholine (ACh) concentration-responses curves. Responses to the exogenous NO donor sodium nitroprusside (SNP) were also identical in both ovariectomized and sham-ovariectomized groups, ruling out differences in smooth muscle reactivity to NO. These results show that NO release is impaired in OVX SHR, an animal model of simultaneous hypertension and menopause.

Acetylcholine↗
PubMed1999

Single-day praziquantel versus 1-week albendazole for neurocysticercosis.

The efficacy of albendazole (15 mg/kg/d for 1 week) was compared with praziquantel (100 mg/kg in three divided doses at 2-hour intervals) for therapy of parenchymal brain cysticercosis. Ten patients were treated with albendazole and 10 patients with praziquantel. Although the total number of cysts was significantly reduced from 64 to 7 in patients treated with albendazole and from 59 to 24 in those treated with praziquantel, the number of patients improving with albendazole was not significantly different from those treated with praziquantel.

Adult↗
PubMed1999

Automatic segmentation of lung fields on chest radiographic images.

In this work we have implemented a system for the automatic segmentation of lung fields in chest radiographic images. The image analysis process is carried out in three levels. In the first one we perform operations on the image that are independent from domain knowledge. This knowledge is implicitly and not very elaborately used in the intermediate level and used in an explicit manner in the high level block, globally corresponding to the idea of progressive segmentation. The representation of knowledge in the high level block is in the form of production rules. The control structure is in general bottom-up but there are certain hybrid control stages, in which the control is driven by the region model (main organs) we are seeking. We have applied the global system to a set of 45 posteroanterior (PA) chest radiographs, obtaining a mean degree of overlap with contours drawn by radiologists of 87%.

Algorithms↗
PubMed1998

Computer-aided diagnosis: a neural-network-based approach to lung nodule detection.

In this work, we have developed a computer-aided diagnosis system, based on a two-level artificial neural network (ANN) architecture. This was trained, tested, and evaluated specifically on the problem of detecting lung cancer nodules found on digitized chest radiographs. The first ANN performs the detection of suspicious regions in a low-resolution image. The input to the second ANN are the curvature peaks computed for all pixels in each suspicious region. This comes from the fact that small tumors possess and identifiable signature in curvature-peak feature space, where curvature is the local curvature of the image data when viewed as a relief map. The output of this network is thresholded at a chosen level of significance to give a positive detection. Tests are performed using 60 radiographs taken from routine clinic with 90 real nodules and 288 simulated nodules. We employed free-response receiver operating characteristics method with the mean number of false positives (FP's) and the sensitivity as performance indexes to evaluate all the simulation results. The combination of the two networks provide results of 89%-96% sensitivity and 5-7 FP's/image, depending on the size of the nodules.

Diagnosis, Computer-Assisted↗
PubMed1998

Computer-aided diagnoses: automatic detection of lung nodules.

This work describes a computational scheme for automatic detection of suspected lung nodules in a chest radiograph. A knowledge-based system extracts the lung masks over which we will apply the nodule detection process. First we obtain the normalized cross-correlation image. Next we detect suspicious regions by assuming a threshold. We examine the suspicious regions using a variable threshold which results in the growth of the suspicious areas and an increase in false positives. We reduce the large number of false positives by applying the facet model to the suspicious regions of the image. An algorithmic classification process gives a confidence factor that a suspicious region is a nodule. Five chest images containing 30 known nodules were used as a training set. We evaluated the system by analyzing 30 chest images with 40 confirmed nodules of varying contrast and size located in various parts of the lungs. The system detected 100% of the nodules with a mean of six false positives per image. The accuracy and specificity were 96%.

Algorithms↗
PubMed1998

[Bilateral medial bulbar infarct related to dolichoectasia of the vertebral artery].

INTRODUCTION AND CLINICAL CASE: A 58-year-old hypertensive man presented with the sudden onset of quadriplegia and inability to protrude the tongue. Magnetic resonance imaging showed a bilateral medial medullary infarction associated with an abnormally dilated and partially occluded vertebral artery. CONCLUSION: This is the first clinicoradiological report of a bilateral medial medullary infarction related to vertebral artery dolichoectasia.

Arterial Occlusive Diseases↗
PubMed1996

Effects of tamoxifen on serum lipid and apolipoprotein levels in postmenopausal patients with breast cancer.

Serum lipids and apolipoprotein levels were measured in twenty postmenopausal women with primary breast cancer, before and three months after tamoxifen therapy (10 mg twice a day). Tamoxifen caused a significant reduction in total serum cholesterol (10%; P < 0.02), and in low-density lipoprotein cholesterol (17%; P < 0.01), and a significant 47% increase in the subclass 2 of the high density lipoprotein cholesterol (P < 0.01). In addition, tamoxifen caused a 16% increase in apolipoprotein A-I, a 12% decrease in apolipoprotein B (P < 0.05), and a 37% reduction in the serum concentration of lipoprotein (a) (P < 0.01). These results show that tamoxifen brings about an important improvement in serum lipid profile.

Aged↗
PubMed1996

Immunoglobulin G subclass measurements in recurrent aphthous stomatitis.

We have measured serum levels of IgG subclasses and total IgG, IgA and IgM in a group of 34 recurrent aphthous stomatitis (RAS) patients. At the time of blood collection, 23 of the 34 patients had active oral lesions. The remaining 11 patients were at an inactive stage. All measurement were performed in the Beckmann 360 Array Protein System. Serum levels of IgG2 subclass were significantly lower (P < 0.05) in the whole group of patients (34) when compared to the control group. This relationship was still significant (P < 0.05) when only the 11 patients without active oral lesions were considered but disappeared in patients at an active stage. We conclude that low serum levels of IgG2 may play a role in the pathogenesis of RAS, just as in other recurrent infectious diseases, and that serum levels of this immunoglobulin subclass, as well as total IgA, may undergo transient changes, depending on the different periods of activity and quiescence of the disease.

Adolescent↗
PubMed1993

Stroke subtypes among Hispanics living in Guayaquil, Ecuador. Results from the Luis Vernaza Hospital Stroke Registry.

BACKGROUND AND PURPOSE: Racial differences in stroke subtypes have been documented. Asians have a higher rate of cerebral hemorrhage than whites; however, there is little information about stroke subtypes among Hispanics. The purpose of this study was to determine the patterns of stroke subtypes in a population of Hispanics. METHODS: Five hundred consecutive patients with a first stroke were included. Patients were collected from hospital wards, the emergency department, and the outpatient clinic to ensure inclusion of patients with a wide range of stroke severity. Computed tomography was available in all cases. Patients with pure subarachnoid hemorrhage were excluded. RESULTS: There were 313 (62.6%) patients with an infarct and 187 (37.4%) with a hemorrhage. Hypertensive arteriolopathy was the most common cause of both infarcts and hemorrhages. The carotid territory was involved in 70.6% of the 313 patients with infarcts, the vertebrobasilar territory in 17.9%, multiple territories in 6.7%, and a watershed area in 4.8%. Hemorrhages were most often lobar (36.4%), followed by putaminal (30.5%), brain stem (9.1%), cerebellar (8%), thalamic (8%), ventricular (5.3%), and caudate (2.7%). CONCLUSIONS: This hospital-based stroke registry suggests that stroke in Hispanics has a pattern different from that in whites but similar to that in Asians. Cerebral hemorrhages occur three times more frequently in Hispanics than in whites.

Adult↗
PubMedDate not supplied

Non-traumatic intracerebral hemorrhage in young adults living in Guayaquil, Ecuador (South America): analysis of 151 patients.

We studied 151 patients aged 15 to 44 years with non-traumatic intracerebral hemorrhage admitted to a large public hospital over a 10-year period. Patients were evaluated for an association of death or severe disability after the stroke with the following variables: sex, age, location of the hemorrhage, and possible etiology. Lobar hemorrhages were found in 63 (41.7%) patients, putaminal hemorrhages in 39 (25.8%), posterior fossa hemorrhages in 24 (15.9%), and hemorrhages in other locations in 25 (16.6%). A possible etiology was determined in 109 (72.2%) patients. Hypertensive arteriolopathy accounted for 60 (39.7%) cases, rupture of a saccular aneurysm or a vascular malformation for 33 (21.9%), and other etiologies for 16 (10.6%). Thirty-four (22.5%) patients died after the acute event. The age of the patient, the location, and the etiology of the hemorrhage had no prognostic significance for mortality. In contrast, these factors predicted the degree of functional recovery in survivors. The best prognosis was noted in patients younger than 35 years with lobar hemorrhages of undetermined etiology, and the worst prognosis was noted in patients aged 35-44 years with putaminal or posterior fossa hemorrhages related to hypertensive arteriolopathy.

Activities of Daily Living↗