Biomedical subjects

M Shaver

Publications and source records attributed to M Shaver.

5 recordsLinked to original sources

PubMed2005

Neutron detection via bubble chambers.

Research investigating the application of pressure-cycled bubble chambers to fast neutron detection is described. Experiments with a Halon-filled chamber showed clear sensitivity to an AmBe neutron source and insensitivity to a (137)Cs gamma source. Bubble formation was documented using high-speed photography, and a ceramic piezo-electric transducer element registered the acoustic signature of bubble formation. In a second set of experiments, the bubble nucleation response of a Freon-134a chamber to an AmBe neutron source was documented with high-speed photography.

Journal Article↗

PubMed1994

Significance of a first-time atypical Papanicolaou smear in a young, high-risk African-American and Latino-American population.

The first atypical Papanicolaou smear in young, sexually active Latino and African-American women of low socioeconomic status may be predictive of underlying cervical neoplasia and human papillomavirus infection of significant quantity. The optimal management of first-time atypia on routine Pap smear has not been established. In many clinics, colposcopically directed sampling of the cervix is recommended only if atypia persists following specific or nonspecific treatment of cervicitis or after an arbitrarily determined time interval. Others recommend immediate colposcopic evaluation. To determine the best approach to the first-time atypical Pap smear in young minority women at high risk for the development of cervical cancer, 250 such patients were evaluated with colposcopically directed biopsy of the cervix prior to any form of therapy. Pap smears were repeated at the time of colposcopy. Histologically, there was evidence of cervical intraepithelial neoplasia in 41% of patients and human papillomavirus infection in 86%. Repeat Pap smears predicted the presence of cervical intraepithelial neoplasia in only 24% of patients. Immediate colposcopic evaluation represents the most prudent approach to the first-time atypical Pap smear in young, high-risk minority women.

Adolescent↗

PubMed1994

Extracorporeal membrane oxygenation support as a bridge to pediatric heart transplantation.

BACKGROUND: Mechanical circulatory support for intractable heart failure as a bridge to transplantation has been used infrequently in children. The lack of clinically available ventricular assist devices has resulted in the use of conventional extracorporeal circuits with oxygenator as the main modality for circulatory support. In this study we reviewed our experience with extracorporeal membrane oxygenation (ECMO) support in children with irreversible heart failure who were awaiting heart transplantation. METHODS AND RESULTS: Since 1985, 14 children were placed on ECMO support for circulatory failure and were considered candidates for heart transplantation: 8 children had postcardiotomy contractile failure, 3 had dilated cardiomyopathy, and 3 had viral myocarditis. Five of these children had cardiac arrest and were placed on support during cardiopulmonary resuscitation. Mean duration of ECMO support was 109 +/- 20 hours. Eight patients developed pulmonary edema requiring decompression of the left ventricle, 3 by blade atrial septostomy and 5 by left atrial vent cannula. Nine of 14 received a heart transplant, 1 child recovered spontaneously (myocarditis), and 4 died of sepsis on ECMO. Of the children who received transplants, 6 were early survivors with 1 late death (lymphoproliferative disease), for a total of 7 of 14 (50%) early and 6 of 14 (43%) late survivors. CONCLUSIONS: Our experience suggests that ECMO is an effective means of circulatory support as a bridge to transplantation in children. Decompression of the left ventricle is often required to prevent pulmonary edema. Sepsis and bleeding remain a limitation to prolonged mechanical support with ECMO in children.

Adolescent↗

PubMed1991

Magnetic resonance imaging of chest wall lesions.

Magnetic resonance imaging (MRI) demonstrates surface anatomy, nerves, and soft tissue pathology. Selective placement of the cursor lines in MRI displays specific anatomy. The MR images can then be used as adjunct in teaching surface anatomy to medical students and to other health professionals. Because the normal surface anatomy could be imaged at UCLA's radiology department, it was decided to image soft tissue abnormalities with MR to assist in patient care. Patients imaged were scheduled for special procedures of the chest or staging lymphangiograms. Patients were placed into categories depending on known diagnosis or interesting clinical presentation. The diagnostic categories included Hodgkin's disease, melanoma, carcinomas (eg, lung or breast), lymphedema, sarcomas, dermatological disorders, and neurological disorders. All images were orchestrated by the radiologist. This article discusses both the teaching and clinical impact on patient care.

Adult↗

PubMed1986

Neighborhood analysis of low magnification structures (glands) in healthy, adenomatous, and carcinomatous colon mucosa.

A new algorithm analyzing neighborhood conditions of adenomatous tissue is is introduced. Using O'Callaghan's definition of neighborhoods, a graph theory approach for measuring histomorphological structures can be created as follows: glands are defined as vertices and the coherence of neighboring glands as edges. The procedure leads to an unoriented, well-defined graph which contains information usually not measurable by conventional morphometric analysis. Measurements on healthy mucosa, tubulo-villous adenoma and highly to moderately differentiated adenocarcinoma of colon revealed statistically significant differences (p less than or equal to 0.05) for the following parameters: number of vertices, number of edges, frequency distribution of n-stars and of n-closed paths. Correct separation and reclassification of 83% of cases could be carried out using discriminant analysis. 11/15 cases (73%) could be classified correctly in a prospective group based upon the learning set. The significance of these findings for automatic pattern recognition in histopathology is discussed.

Adenocarcinoma↗