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Biomedical subjects

C Harper

Publications and source records attributed to C Harper.

123 records · Page 7Linked to original sources
PubMedDate not supplied

Intracranial cavity volumes: a new method and its potential applications.

Variations of brain weights and volumes often reflect pathological states. However, these parameters are more meaningful when related to intracranial volume. The most useful derived parameter is the difference between intracranial volume and brain volume expressed as a percentage (potential intracranial space). In patients with cerebral atrophy the potential intracranial space will be large, whereas in patients with space occupying lesions or brain swelling the potential intracranial space will shift towards 0%. Previously described techniques to determine intracranial volume have been unsatisfactory for routine application in the autopsy room. The technique described herein is based on the production of a permanent polyurethane cast of the cranial cavity. The casts can be formed in about 20 min with little modification of standard autopsy technique. Duplicate casts were made in twenty-seven unselected cases and in all cases there was less than 2% error in duplicate cast volumes. The cast provides a permanent record of the size and shape of the cranial cavity and can be used to determine intracranial volume or other intracranial dimension. The usefulness of the derived parameter, potential intracranial space, is evident in some of the cases studied.

Adult↗
PubMedDate not supplied

Provision of hormonal contraceptives without a mandatory pelvic examination: the first stop demonstration project.

CONTEXT: First Stop, an 18-month demonstration project that operated in 1996-1997, was designed to offer low-income adult women in California hormonal contraceptives without requiring a pelvic examination. METHODS: An evaluation was undertaken to assess the contraceptives adopted by First Stop clients, compare health risks of these women with risks among women using traditional family planning clinics and assess clients'satisfaction. Data on 2,065 First Stop clients and 1,507 women attending traditional clinics were collected through several self- and clinician-administered instruments, including questionnaires, a telephone survey and medical chart abstractions. RESULTS: After the initial First Stop visit, 38% of women adopted a more effective method than they had used at last sex, 4 7% remained with the same method, 12% switched to a less-effective method and 3% accepted no method. Of clients who were referred for additional medical care, 73% followed through on their referrals. Compared with clients at traditional clinics, First Stop clients were less likely to have a regular source of health care, but more likely to have made a health care visit in the past year. Most First Stop clients valued the project's services; 76% said it was important to be able to receive pills or injections without a pelvic examination. CONCLUSIONS: Programs that provide hormonal contraceptives without requiring a pelvic examination can expand low-income women's access to these methods and improve the chances that they will obtain other reproductive health services.

Adult↗
PubMedDate not supplied

"Rhabdoid meningioma" lacking malignant features. Report of two cases.

We report 2 cases of meningiomas with rhabdoid morphology but lacking histological features of malignancy. Both occurred in adult women, one arising from the superior surface of the tentorium and the other in the Sylvian fissure. The tumors showed light microscopic, immunohistochemical and ultrastructural evidence of meningothelial differentiation together with diffuse or focal areas exhibiting rhabdoid morphology. The rhabdoid areas were characterized by cells with large cytoplasmic eosinophilic inclusions and large eccentric nuclei. Both cases showed areas with sheet-like growth and one had macronucleoli and brain invasion. The same case showed areas of necrosis that most likely related to pre-operative arterial embolization. Unlike most cases reported in the literature, these "rhabdoid meningiomas" lacked significant mitotic activity or other atypical features. The diagnostic and prognostic significance of this tumor entity is discussed along with a review of the literature.

Adult↗
PubMedDate not supplied

Species differences in benzene hydroxylation to phenol by pulmonary and hepatic microsomes.

The metabolism of benzene to phenol by microsomal preparations from lung and liver has been compared in hamsters, rats, and rabbits. There were wide differences in the apparent Vmax of benzene hydroxylation among the various species and tissues and smaller differences in the apparent KM values for benzene hydroxylase. Benzene can inhibit its own metabolism in vitro when present in high concentrations. Phenol was the only metabolite of benzene identified, under the conditions of the assay, in incubation mixtures containing microsomes from lung or liver of any of the three animal species. When incubated with microsomes under the conditions used to measure benzene metabolism, phenol was further metabolized in liver but not in lung preparations. Phenol metabolism was almost completely inhibited when 11.2 mM benzene was included in the incubation mixture containing hepatic microsomes. The variation in rates of benzene hydroxylation by microsomal preparations from lungs or livers of the three animal species was similar to the variation in rates of benzypyrene hydroxylation in the same preparations.

Aniline Hydroxylase↗
PubMedDate not supplied

The biotransformation of p-xylene to a toxic aldehyde.

Rats given a single ip injection of p-xylene suffered 65% loss of pulmonary microsomal p-xylene hydroxylase activity. The activity was protected by pretreating the rats with phenobarbital, which increased hepatic p-xylene hydroxylase and cytosolic aldehyde dehydrogenase activities, but had no effect on alcohol dehydrogenase activity in hepatic cytosol. Pretreatment of rats with pyrazole caused a 60% inhibition of liver alcohol dehydrogenase but had no effect on liver aldehyde dehydrogenase activity. This treatment partially protected the pulmonary microsomal p-xylene hydroxylase from inactivation by p-xylene. Experiments in vitro showed that inactivation of cytochrome P-450 by p-xylene required the metabolic conversion of p-xylene to p-tolualdehyde. The reactive intermediate (p-tolualdehyde) required the presence of NADPH to carry out the inactivation. Inasmuch as lung tissues cannot form p-tolualdehyde (because of the low activity of p-methylbenzyl alcohol dehydrogenase), it is assumed that the inactivation of lung enzymes in vivo following exposure to p-xylene was due to the aldehyde intermediate which is formed in the liver and transported to the lung.

Aldehydes↗
PubMedDate not supplied

CT scanners: the industry behind the science.

The history of computerized tomography scanners is an interesting study. Probably no medical technology has made such a spectacular splash as has this one. Coming on the scene just as medical costs were skyrocketing, it has been the subject of much controversy over its medical value in terms of other diagnostic technologies and its high cost. This article details some of the behind-the-scenes activity in the development and production of computerized tomography units.

Cost Control↗
PubMedDate not supplied

Knowledge and perceptions of emergency contraceptive pills among a college-age population: a qualitative approach.

Results from focus-group discussions with a population of university students who have convenient access to emergency contraceptive pills show that basic awareness about this method is high, although specific knowledge on appropriate use, such as the time limit for use, the level of effectiveness and the possible side effects, is lacking. Approval of the method is widespread among both female and male students, although students did voice anxieties about irresponsible use and the lack of protection against the human immunodeficiency virus and other sexually transmitted diseases. Many of their concerns stem from incomplete information about how the regimen works. Students noted how rarely emergency contraceptive pills are discussed, and were curious to know more. They asked for routine education on the method, as well as more general discussion.

Alcohol Drinking↗