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Biomedical subjects

M Zevallos

Publications and source records attributed to M Zevallos.

10 recordsLinked to original sources
PubMed2006

Computer-controlled optical scanning tile microscope.

A new type of computer-controlled optical scanning, high-magnification imaging system with a large field of view is described that overcomes the commonly believed incompatibility of achieving both high magnification and a large field of view. The new system incorporates galvanometer scanners, a CCD camera, and a high-brightness LED source for the fast acquisition of a large number of a high-resolution segmented tile images with a magnification of 800x for each tile. The captured segmented tile images are combined to create an effective enlarged view of a target totaling 1.6 mm x 1.2 mm in area. The speed and sensitivity of the system make it suitable for high-resolution imaging and monitoring of a small segmented area of 320 microm x 240 microm with 4 microm resolution. Each tile segment of the target can be zoomed up without loss of the high resolution. This new microscope imaging system gives both high magnification and a large field of view. This microscope can be utilized in medicine, biology, semiconductor inspection, device analysis, and quality control.

Equipment Design↗
PubMed2005

Wireless spectroscopic compact photonic explorer for diagnostic optical imaging.

A remote, small-size spectroscopic-based device called Compact Photonics Explorer (CPE) was designed, assembled, and tested for medical and non-medical spectroscopic and imaging applications. Spatial images acquired using the spectroscopic CPE are presented. Operational principles are demonstrated for various biomedical and non-medical applications.

Colorimetry↗
PubMed2004

Near infrared spectroscopy and imaging to probe differences in water content in normal and cancer human prostate tissues.

The content of water in cancerous and normal human prostate in vitro tissues was shown to be different using near infrared (NIR) spectroscopy. The water absorption peaks at 1444 nm and 1944 nm are observed in both types of prostate tissues. The measurements show that less water is contained in cancerous tissues than in normal tissues. The OH stretching vibrational overtone mode at 1444 nm and other water overtone modes provide key spectroscopic fingerprints to detect cancer in prostate tissue. Transmission and backscattered spectral imaging were measured in cancer and normal prostate tissues. The degree of polarization for 700 nm, 800 nm, 1200 nm, and 1450 nm is larger for normal than for cancer tissues. The knowledge about water content offers a potential as a diagnostic tool to better determine and image cancer in prostate and in other tissues types such as breast and cervix using the absorption from vibrational overtones of H(2)O molecules in the NIR.

Body Water↗
PubMed1996

Time-resolved optical diffusion tomographic image reconstruction in highly scattering turbid media.

The image of an object hidden in highly scattering media was reconstructed using a fast, noise-resistant algorithm newly applied to diffusion tomography. A pulsed light source producing scattered and transmitted light is examined at multiple times. Multiple source detector pairs around the medium are used to obtain data in many different directions. An inverse scattering algorithm with nonuniform regularization achieves rapid inversion convergence.

Journal Article↗
PubMed1994

Relationship between body mass index, age, and serum adrenal androgen levels in Peruvian children living at high altitude and at sea level.

We have determined the relationship between body mass index (BMI) and serum adrenal androgen levels when age is controlled for in children, aged 7-12 years, living in Lima (150 m above sea level) and in Cusco (3400 m above sea level). The purpose of the study was to determine whether the relationship of serum adrenal androgen levels with both BMI and age differs between low and high altitude. The ratio weight/height2 is not an adequate marker of BMI because it correlates with height in children from Lima and Cusco. The ratio weight/height2.3 correlates with body weight but not with height and was used in the present study as the BMI. From age 7 to 12 years, the BMI increased significantly with age only in boys from sea level and in girls from high altitude. The study demonstrates that serum adrenal androgen levels are not related to BMI in either sea-level or high-altitude children when the effect of age is removed statistically. These data suggest that BMI in children is not related to serum levels of adrenal androgens and that delayed age of adrenarche observed in children at high altitude may be due to factors other than nutritional status.

Age Factors↗
PubMed1986

Histologic conversion of an unfavorable primary brain lymphoma to a favorable type.

Histologic conversion of a less aggressive non-Hodgkin's lymphoma to a more aggressive type has been established in several studies. Neither this trend nor vice versa has been reported in primary brain lymphoma, because of the poor median survival in the clinical setting which precludes further invasive procedures. The authors report a case of transformation of a primary brain lymphoma, histiocytic type, to poorly differentiated lymphocytic lymphoma 2 1/2 years after treatment with radiation and intrathecal methotrexate.

Aged↗
PubMedDate not supplied

[Peutz-Jeghers syndrome. Apropos a familial case at Hospital Arzobispo Loayza].

The Peutz-Jeghers syndrome is a rare dominant autosomic, entity characterized by hyperpigmented lesions on the lips, hands and feet; with presence of gastrointestinal polyps producing acute or chronic anemia, intestinal obstruction, and/or abdominal pain. This polyps histologically are hamartomas; recent studies indicate a real risk for transformations in the malignant neoplasia. The high and low endoscopies and the intraoperative enteroscopy with polypectomy are the election treatment, improving prognosis quality on these patients. We describe a familiar case of a female patient 24 years old showing a repeated picture of intestinal subocclusion; her brother presented a similar clinical picture, and her mother presented the same syndrome, dying of carcinoma in the colon; also her child, at one and a half year old presented hyperpigmented lesions on the lips.

Adult↗