PubMed Health⌕ Search

Biomedical subjects

S Callahan

Publications and source records attributed to S Callahan.

At least 37 records · Page 2Linked to original sources
PubMed1991

Timely arguments.

Explore the source record for details and available documents.

Abortion, Induced↗
PubMed1991

The viability of abstinence in an inner city adolescent population.

The purpose of our study was to investigate the different variables that lead teenagers to have sex, the psychological consequences they face as a result of having sex, and the viability of abstinence as an alternative. We used an anonymous self-administered questionnaire to address such issues as age of first intercourse and influence of family, peers, and physical consequences (ie, pregnancy, sexually transmitted diseases, and AIDS). Our research concluded that not only are teens having sexual intercourse at early ages, but that this early experience may be having detrimental consequences on their levels of self-esteem. We propose that the adolescent's search for identity is a strong motivational factor in engaging in sexual intercourse at an early age, and that delaying first coitus or choosing abstinence as a birth control method can be both empowering and ego-enhancing for the teenage client.

Adolescent↗
PubMed1990

Incubation periods and histopathological changes in mice injected stereotaxically in different brain areas with the 87V scrapie strain.

After stereotaxic injection into five different brain areas (cortex, caudate nucleus, substantia nigra, thalamus and cerebellum) of IM mice with the 87V scrapie strain, the cerebellum had the shortest incubation period. The vacuolation pattern was similar regardless of the area injected with extensive vacuolation in the thalamus, mesencephalon and hypothalamus. The pattern of amyloid plaques differed markedly depending on the area injected. In particular, no plaques were seen anywhere in the brain after injection into intact cerebellum, whereas injection into the four cerebral areas yielded plaques in the forebrain but not in the cerebellum. The incubation period after injection into bisected cerebella was much longer than after injection into intact cerebella. Mice injected on one side of bisected cerebellum had amyloid plaques in the forebrain but not in the cerebellum. There is a discussion of the finding that, although no plaques and virtually no vacuolation were seen in the cerebellum, the shortest incubation period occurred after injection into intact cerebellum.

Amyloid↗
PubMed1988

The examination of illicit cocaine.

A laboratory system of examination of illicit cocaine exhibits is described. Separation and identification of many of the components in exhibits are achieved by the use of capillary column gas chromatography and a Finnigan ion trap detector. Further examination and quantitation of the components of exhibits is achieved using two high performance liquid chromatographic (HPLC) systems. Both of these systems use identical reverse phase C8 columns. System 1 employs a solvent composed of 40% acetonitrile, 10% tetrahydrofuran and 50% 0.1% v/v aqueous triethylamine. The eluant is monitored at 280 nm. This system is preferred for routine quantitative analysis of cocaine and related alkaloids in exhibits. System 2 employs a solvent composed of 30% acetonitrile and 70% 0.05M phosphate buffer (pH = 5.0). The eluant from this system is monitored at both 220 and 280 nm. This system offers advantages in sensitivity. The relative retention times of a number of relevant substances as determined with gas chromatography and the two HPLC systems are given. The utility of the methodology for the identification and comparison of exhibits is demonstrated.

Chromatography, High Pressure Liquid↗
PubMed1987

Bayesian statistical theory in the preoperative diagnosis of pulmonary lesions.

We used a computerized Bayesian algorithm to assist in the preoperative diagnosis of pulmonary lesions. One hundred consecutive patients who were undergoing exploratory thoracotomy for newly discovered pulmonary lesions were prospectively evaluated. The Bayesian model used a total of 44 preoperative clinical and roentgenographic factors to categorize the lesions as benign or malignant. The Bayesian algorithm correctly categorized 96 of the 100 lesions, thereby providing an accuracy of 96 percent. The sensitivity of the model was 98 percent and the specificity was 87 percent. All but two of the 85 malignant lesions were correctly categorized and 13 of the 15 benign lesions were correctly analyzed by the model. These results indicate that computer-assisted diagnosis using the Theorem of Bayes may provide valuable preoperative information for the management of selected patients.

Adolescent↗