Biomedical subjects

M Castillo

Publications and source records attributed to M Castillo.

At least 55 records · Page 3Linked to original sources

PubMed2000

An in vitro model of ischemic-like stress in retinal pigmented epithelium cells: protective effects of antioxidants.

We have developed a model of in vitro cell oxidative stress in bovine retinal pigment epithelium cells exposed to a ischemia-like condition obtained by interference with glucose utilization through both oxidative phosphorylation and glycolysis. This resulted in a statistically significant decrease of the intracellular ATP levels, which reflects a bioenergetic decline similar to that associated with mitochondrial damage or loss in normal post-mitotic cells aging in vivo. This new model of cellular oxygen stress seems adequate for investigation of the protective action of antioxidants, in agreement with our finding of a statistically significant increase in the ATP levels over the values of the non-treated samples in retinal pigment epithelium cells exposed to the above oxygen stress in medium supplemented with 300 microM vitamin C or 10 mM N-acetylcysteine.

Adenosine Triphosphate↗

PubMed2000

The ability of tumor volume to predict local control in surgically treated squamous cell carcinoma of the supraglottic larynx.

PURPOSE: Pretreatment CT volumetric measurement of the primary tumor has been shown to be a predictor of local control in patients with laryngeal carcinoma treated with radiation therapy (RT) alone. A direct association has been demonstrated between tumor volume of supraglottic squamous cell carcinoma (SGSCCA) and local control. However, the association between tumor volume of SGSCCA and local control has not been investigated in patients treated surgically. The purpose of this study was to determine the relationship between SGSCCA tumor volume and local control in patients treated surgically. MATERIALS AND METHODS: Primary site tumor volume was calculated from pretreatment CT studies in 37 laryngeal supraglottic carcinomas treated surgically. All patients had clinical follow-up for evidence of recurrent tumor along the surgical margins at the primary site for a minimum of 2 years after completion of treatment. Statistical analysis consisted of Mantel-Haenszel chi-square tests and Fisher's exact test. RESULTS: Overall local control rate was 92% (33 of 37). Tumor volume was significantly associated with local control (p <. 05). Local control rate for tumors with volumes <16 cc was 94% (32 of 34) (p <.05). CONCLUSIONS: Pretreatment CT volumetric analysis is useful for predicting local control in patients with SGSCCA carcinoma treated surgically.

Adult↗

PubMed2000

MRI in a patient with the Worster-Drought syndrome.

We describe a patient with the Worster-Drought syndrome (congenital suprabulbar paresis), thought to be a failure of development of the corticobulbar tracts. MRI showed bilateral perisylvian cortical dysplasia.

Bulbar Palsy, Progressive↗

PubMed2000

Radiographic findings in tuberculosis of the calvarium.

We reviewed the pattern of involvement of the calvarium by tuberculosis (TB) in five patients and the role of imaging in its management. Four patients presented with localised scalp swelling and one with generalized seizures. Radiographs revealed lucent lesions with minimal surrounding sclerosis in the frontal (2), parietal (2) and occipital (1) bones. CT showed lesions involving the entire thickness of the calvarium and accompanying contrast-enhancing soft tissue. The patient presenting with seizures had a ring-enhancing lesion in the parietal lobe in addition to the extra-axial lesions. Although radiographs in all cases demonstrated calvarial TB, CT showed the extent of the defect, involvement of adjacent soft tissues, and in one case an intra-axial lesion. Radiographs suffice for follow-up of these patients.

Adolescent↗

PubMed2000

Cerebral amobarbital sodium distribution during Wada testing: utility of digital subtraction angiography and single-photon emission tomography.

We aimed to determine if the cerebral distribution of anesthetic during Wada testing is reflected by findings on digital subtraction angiography (DSA) and single-photon emission computed tomography (SPECT) and if the findings on these studies are relevant to the outcome of the Wada test. We carried out selective internal carotid artery (ICA) DSA on 29 patients underwent studies prior to a Wada test. In patients without angiographic cross-filling, amobarbital and a radiotracer were injected into each ICA, beginning with the epileptogenic side. In patients with cross-filling, the ICA ipsilateral to the epileptogenic focus was injected with amobarbital and radiotracer while other was injected with amobarbital alone. We analyzed the DSA studies for cross-filling and filling of the posterior cerebral arteries (PCA). We reviewed the SPECT for activity in the territories of the anterior, middle cerebral, and posterior cerebral arteries. We compared the results of both studies with the success or failure of the neuropsychological portion of the Wada test. In 20 patients without cross-filling, the results of DSA and SPECT were comparable: symmetrical hemisphere activity was seen. In nine patients with cross-filling, SPECT showed bilateral, almost symmetrical activity. Filling or nonfilling of the PCA correlated with activity (or lack of it) in the medial temporal and occipital regions in all patients. The Wada test was considered successful in all patients. The findings on SPECT did not alter interpretation of the Wada test and we suggest that it may not be needed in all patients undergoing Wada testing.

Adolescent↗

PubMed2000

Imaging in isolated sacral tuberculosis: a review of 15 cases.

OBJECTIVE: To review imaging studies of isolated involvement of the sacrum due to tuberculosis and determine the role of imaging in the diagnosis and management of these patients. DESIGN AND PATIENTS: A retrospective analysis of 15 cases of isolated sacral tuberculosis imaged with MR imaging was performed. The CT images were also reviewed where available, and the various lesion characteristics were identified. We also reviewed the medical records in an attempt to determine the impact of the imaging studies on the management of these patients. RESULTS: Fifteen patients (5 male, 10 female) presented with symptoms of 3-15 months' duration. Chronic localized backache with muscle spasm was the commonest presenting symptom; discharging sinuses with abscess formation was found in six patients, five of whom were children. MR imaging of the sacrum revealed a hypointense marrow signal on T1-weighted images and hyperintense signal on T2-weighted images in 14 of 15 patients, the S2 vertebra being always involved. CT revealed osteolytic changes in the sacrum in all the five patients in whom CT was performed. All patients showed marked clinical improvement within 1 year of anti-tuberculous chemotherapy. CONCLUSION: Isolated tuberculosis of the sacrum is uncommon but should be suspected in patients presenting with chronic low backache or children with discharging sinuses/abscesses and showing sacral destruction on CT or MR imaging. MR imaging can identify cases and enables early institution of antituberculous chemotherapy.

Adolescent↗

PubMed2000

Thickness measurement in composite materials using lamb waves viscoelastic effects.

Pulse propagation in plates has been investigated with the identification of Lamb modes. The application of this technique to the measurement of thickness in composite and coarse materials was previously evaluated. As a sequel, results of the application of this technique taking into account the viscoelastic properties of PVC and ferrocement are presented.

Elasticity↗

PubMed2000

Perception of head orientation.

There are two visual components to gaze: head orientation and orientation of the eyes relative to the head. This study explores the accuracy with which subjects can discriminate head orientation when the eyes are centered in the head. Discrimination thresholds averaged 1.9 degrees of head rotation for base head orientations of 0 degree and 15 degrees, but discrimination was markedly poorer around a 30 degrees head orientation. Results were independent of spatial frequency and size over a 4-fold range. Neither negative contrast nor head inversion affected discrimination. Experiments dissociating the internal features from head outline revealed the presence of two main cues to discrimination: deviation of the head profile from bilateral symmetry, and deviation of nose orientation from vertical. Simulations show that model V4 units revealed in previous experiments with Glass patterns can extract the relevant head orientation information. The data are consistent with neurological data indicating a selective loss of face recognition in prosopagnosia with spared gaze discrimination.

Discrimination, Psychological↗

PubMed2000

Diffusion-weighted imaging in the evaluation of intracranial lesions.

Conventional magnetic resonance (MR) imaging is able to show pathology early on and to provide the radiologist with some degree of lesion characterization based on the relaxation time of different tissues. Many times, however, conventional MR imaging is not capable of depicting abnormalities at a time when early therapy may be successful, or of differentiating among different types of lesions before surgery. Diffusion-weighted imaging (DWI), a technique that is relatively new, is rapidly gaining popularity. Its increased use stems from the fact that many of the newer MR units are echo-planar capable. Although DWI may be obtained without echo-planar techniques, most DWI is now obtained by using gradients capable of very fast rising times. Echo-planar DWI may be obtained in a matter of seconds and, thus, is much less sensitive to bulk motion than other imaging techniques. Although DWI has been used extensively for the evaluation of acute cerebral infarctions, new uses for it are being explored constantly. In this article we address the nature of DWI and its use in the stroke patient as well as in other clinical situations where we believe it is useful.

Brain↗

PubMed2000

Clinical applications of FLAIR, HASTE, and magnetization transfer in neuroimaging.

We review the clinical utility of three commonly used and relatively new magnetic resonance techniques as it pertains to neuroimaging. These techniques include fluid-attenuated inversion-recovery (FLAIR) images, half-Fourier acquisition single-shot turbo spin echo (HASTE) images, and magnetization transfer (MT). These techniques may be used to improve image quality and, in some cases, increase the sensitivity and the specificity of magnetic resonance imaging of the brain and spine.

Central Nervous System↗

PubMed2000

Proton MR spectroscopy of the brain.

Magnetic resonance spectroscopy (MRS) has been shown to be an effective noninvasive diagnostic tool that can be used to monitor serially biochemical and metabolic changes in serial disease processes that affect the brain. MRS is now a clinical tool that is reimbursable. This article reviews MRS physics, techniques, pulse sequences, and the clinical applications of MRS.

Brain↗

PubMed2000

Fish oil reduces cholesterol and arachidonic acid levels in plasma and lipoproteins from hypercholesterolemic chicks.

The value of fish oil for prevention and/or treatment of human atherosclerosis has not been fully established. This study shows that replacement of saturated fat in young chick diet with menhaden oil produced a significant reversion of the hypercholesterolemia previously induced by coconut oil feeding. Fish oil also produced a clear decrease of plasma triacylglycerol levels. Coconut oil increased the percentages of 12:0 and 14:0 fatty acids, while menhaden oil increased those of 20:5 n-3 and 22:6 n-3. Percentages of 20:4 n-6, 18:2 n-6 and 18:1 n-9 significantly decreased by fish oil addition to the diet. Total cholesterol, phospholipid and protein contents of high and low density lipoproteins increased by coconut oil feeding. When coconut oil was replaced by menhaden oil, total cholesterol was significantly reduced in high, low and very low density lipoproteins. All chemical components of VLDL were decreased by menhaden oil feeding. Our results show a strong hypocholesterolemic effect of menhaden oil when this fat was supplemented to hypercholesterolemic chicks. The clear decrease found in arachidonic acid content of chick plasma and lipoproteins may contribute to the beneficial effects of fish oil consumption by lowering the production of its derived eicosanoids.

Animals↗

PubMed2000

Determination of non-ionic surfactants and polar degradation products in influent and effluent water samples and sludges of sewage treatment plants by a generic solid-phase extraction protocol.

Non-ionic polyethoxylated surfactants (nonylphenol polyethoxylates, alcohol polyethoxylates), their breakdown products (polyethylene glycol, polyethoxylated nonylphenol carboxylates and polyethoxylated alcohol carboxylates) and other compounds were identified and measured in various waste-water treatment samples (influent, effluent and sludge). A generic protocol involving the use of sequential solid-phase extraction (SSPE) with octadecylsilica and styrene-divinylbenzene cartridges in series and differential elution was used. Fractionated extracts were analyzed by liquid chromatography-mass spectrometry (LC-MS) using atmospheric pressure chemical ionization (APCI) in the positive and negative ionization modes. For sewage treatment plant (STP) sludge, the extraction protocol involved lyophilization of the sludge followed by sonication with MeOH-CH2Cl2 (7 + 3) and final clean-up using the SSPE protocol. Limits of detection for target analytes ranging from 1.1 to 4.1 micrograms L-1 for water samples and from 0.11 to 0.28 mg kg-1 for sludge were achieved. The results obtained demonstrated the inefficient removal of the target analytes in physico-chemical STPs whereas their elimination factors in STPs with biological treatment reached average values of 77, 92 and 98% for alcohol polyethoxylates, nonylphenol polyethoxylates (NPEOs) and polyethylene glycols (PEGs), respectively. Quantitative elimination of coconut fatty acid diethanolamide (CDEA) surfactants in the activated sludge process occurred. In contrast, total removal of NPEOs led to the formation of persistent and toxic metabolites such as nonylphenol which was present in treated effluent as well as in sludge samples with average concentrations ranging from 15.0 to 251.2 micrograms L-1 and from 13.5 to 74.2 mg kg-1, respectively. Polyethoxylated carboxylates and short chain NPEOs were also detected at similar levels in the effluents and sludges. In addition, a linear correlation between the total phenolic concentration (Total Ph) measured by the 4-aminoantipyrine method and the total concentration of nonylphenolic compounds (Total NP) measured by SSPE-LC-APCI-MS was observed.

Gas Chromatography-Mass Spectrometry↗

PubMed2000

Increased frequency of mutations in DNA from infertile men with meiotic arrest.

In diverse organisms from yeast to mice, mutations in numerous genes required for DNA repair may lead to defects in meiosis. Although it is likely that meiosis is conserved throughout evolution, little is known about the genetics of meiosis in humans even though meiotic arrest associated with azoospermia is common. In this work, we compared the sequence fidelity of a polymorphic marker amplified from DNA of two groups of patients: those with testis biopsy suggesting meiotic arrest and those with normal spermatogenesis who were obstructed. We demonstrated that mutations are more common in DNA from testicular tissue derived from men with meiotic arrest than in DNA from testicular tissue derived from men with normal spermatogenesis and physical obstruction (P < 0.05). No mutations were observed in blood tissue from either group of men. This suggests the possibility that defects in genes required in DNA repair could contribute to meiotic arrest in men just as has been observed in other organisms.

Base Sequence↗

PubMed2000

Hypoplasia of the bony canal for the cochlear nerve in patients with congenital sensorineural hearing loss: initial observations.

PURPOSE: To evaluate the length and width of the bony canal of the cochlear nerve in patients with congenital sensorineural hearing loss (SNHL) who have "normal" findings at thin-section computed tomography (CT) of the temporal bone. MATERIALS AND METHODS: The authors retrospectively evaluated the length and width of the bony canal for the cochlear nerve in two groups of patients. The first group was composed of 33 patients with profound SNHL and no demonstrable abnormality at thin-section CT. The control group was composed of 50 patients who underwent temporal bone CT for causes unrelated to SNHL. The mean value +/- SD was calculated for both cohorts. Statistical analysis consisted of the nonparametric Wilcoxon rank sum test with the NPAR1WAY program. RESULTS: The length and width of the bony canal for the cochlear nerve were significantly smaller in patients with SNHL than in the control group (P <.05) CONCLUSION: The hypoplastic bony canal for the cochlear nerve in patients with SNHL may be indicative of a previously unrecognized embryologic malformation of the cochlear nerve.

Adolescent↗

PubMed2000

Cerebral infarctions: evaluation with single-axis versus trace diffusion-weighted MR imaging.

OBJECTIVE: Our purpose was to determine the usefulness of single-axis diffusion-weighted imaging versus trace diffusion-weighted imaging in the evaluation of cerebral infarctions. SUBJECTS AND METHODS: Twenty-six patients harboring 34 infarctions were examined using single-axis and trace diffusion-weighted imaging within 48 hr of the onset of symptoms. Two neuroradiologists who were not aware of the clinical findings reviewed all images obtained with both techniques and noted the following: type of infarction (small [<15 mm] versus territorial), location of infarction, presence of infarction (seen only on single-axis images, seen only on trace images, seen on both), lesion conspicuity (better on single-axis images, better on trace images, or equal on both), and lesion size (larger on single-axis images, larger on trace images, or equal on both). Differences in opinion were resolved by consensus. RESULTS: Of the 18 small and 16 territorial infarctions, all were identified on both single-axis and trace imaging. Lesion conspicuity was judged to be slightly better on trace images for both types of infarctions. Lesion size was judged to be larger on single-axis images for territorial infarctions. CONCLUSION: Both single-axis and trace diffusion-weighted imaging showed all small and territorial cerebral infarctions. Both types of infarctions were slightly larger on single-axis images but this did not affect correct interpretation in any case. The single-axis technique provided sufficient information for the diagnosis of cerebral infarction in our clinical settings.

Acute Disease↗

PubMed2000

Imaging of congenital anomalies of the branchial apparatus.

One of the most challenging topics for radiologists is congenital anomalies arising from abnormal embryogenesis of the branchial apparatus. Defects of the branchial apparatus result in a spectrum of anomalies that includes fistulas, sinuses, cysts, temporal bone anomalies, craniofacial malformations, and systemic disorders. A better understanding of the various radiologic abnormalities is aided by an understanding of their embryonic origins. This article reviews the spectrum of abnormalities that are secondary to anomalous embryogenesis of the branchial arches.

Branchial Region↗

PubMed2000

Imaging of the pediatric orbit.

This article addresses the embryology of the eye, the imaging of common congenital malformations involving the globe, and imaging features of common retro-ocular masses. Clinical entities resulting in alterations in the size and contour, and those producing leukokoria, also are discussed.

Child↗