Biomedical subjects

D Townsend

Publications and source records attributed to D Townsend.

At least 73 records · Page 4Linked to original sources

PubMed1980

Description of an afterloading 192Ir interstitial-intracavitary technique in the treatment of carcinoma of the vagina.

This is a preliminary report of an afterloading 192Ir interstitial-intracavitary technique used in the treatment of carcinoma of the vagina. Thirteen cases of carcinoma of the vagina, stages I through III, were treated at the Southern California Cancer Center and University of Southern California Radiation Medicine Unit between November 1976 and February 1978. The Syed-Neblett perineal template is described in detail, as are the precise clinical application techniques. The hallmarks of the method are: 1) ease of use by the physician, 2) homogeneous radiation dose distribution, and 3) differential radiation dose delivery capabilities. The technique is believed to be an improvement over previous modalities of therapy reported in the literature.

Adult↗

PubMed1979

Actions not words.

The deep-rooted respect of the value of each individual in Sweden is shown in its community-based care of the mentally handicapped. Author looks at the lessons Britain can learn in this field.

Education of Persons with Intellectual Disabilitie↗

PubMed1978

Object reconstruction from focused positron tomograms.

A major problem with the reconstruction of three-dimensional object distributions from focused tomographic images using Fourier transforms is the amplification of statistical noise in certain frequency components. This paper describes the use of a generalised matrix inversion technique to limit noise amplification to a level related to the spatial resolution of the imaging system. The reconstruction method is applied to a simulated positron camera, and results are presented on the imaging of an extended, three-dimensional object distribution. A significant improvement in the elimination of the background is achieved.

Fourier Analysis↗

PubMed1978

Design and preliminary observations of National Cooperative Diethylstilbestrol Adenosis (DESAD) Project.

The National Cooperative Diethylstilbestrol Adenosis (DESAD) Project has completed the major portion of its enrollment phase with the examination of more than 3000 daughters of women taking synthetic nonsteroidal estrogens (denoted DES) during pregnancies occurring from the early 1940s to the mid-1960s. The aims of the Project are to fill urgent needs for information on the prevalence and incidence of structural and epithelial abnormalities or neoplastic changes and their complications in these young women. Participants are grouped by mode of entry as identified by prenatal record review (40.1%), documented as DES-exposed but walking in (25.1%), or referred (22.8%) to the DESAD Project for examination, and not documented as exposed but having gynecologic abnormalities typical of those associated with DES exposure (12.0%). This study cohort, in part having paired controls, will be examined annually for at least 5 years. Details of the design and selected preliminary findings are reported.

Adolescent↗

PubMed1977

Clear cell carcinoma of cervix and vagina in progeny of women who received diethylstilbestrol: three cases with scanning and transmission electron microscopy.

Three cases of clear cell carcinoma of the cervix and vagina in progeny of women administered diethylstilbestrol (DES) were studied ultrastructurally. The patients were young and had a positive history of maternal ingestion of DES during pregnancy. Similar ultrastructural features were observed in all cases. The neoplastic cells were arranged in solid nests or glands. Ultrastructural findings in these cases were similar to those of previously reported clear cell carcinomas of the ovary and endometrium, which seems to indicate a common Müllerian origin11, 16 as opposed to a mesonephric origin. 10 A transition between vaginal adenosis and the neoplasm was not observed.

Adenocarcinoma↗

PubMed1977

Effect of fluoride on the serum lipids of guinea pigs.

The effects of fluoride intake on the serum lipids of guinea pigs were determined in animals provided with either high or low levels of fat in their diet and fluoride in their drinking water. Evidence of the difference in fluoride intake were reflected by serum fluoride contents. The results suggest that, in guinea pigs receiving excess dietary cholesterol, an inadequate fluoride intake is reflected in increased serum cholesterol. Fluoride intake also influence the serum triglyceride levels, but the direction of the response was dependent on the amount of dietary fat. Serum free fatty acids and phospholipids were not influenced by fluoride intake.

Animals↗

PubMed1977

The influence of prostaglandin G2 on platelet ultrastructure and platelet secretion.

Prostaglandin G2 (PGG2) is a labile endoperoxide produced physiologically following exposure of platelets to aggregating agents. We report here studies using isolated PGG2. This agent stimulates a concentration-dependent internal platelet contraction very similar to that produced by the calcium ionophore A23187. EDTA prevented platelet aggregation but did not prevent PGG2-stimulated internal contraction or secretion. In contrast, prostaglandin E1 and dibutyryl cyclic AMP inhich selectively labilizes platelet granules, was added to platelets together with PGG2 there was a superadditive effect on platelet secretion. Thus, granule labilization induced by PMA is a separable phenomenon and complementary to the effect of PGG2 on contraction. The ultimate degree of secretion is dependent on both processes. Studies using additional inhibitors supported the hypothesis that PGG2 activates platelets (either directly or following conversion to thromboxane A2) by transporting calcium from an intracellular store to the cytoplasmic site of the platelet contractile proteins.

Adenosine↗

PubMed1977

The involvement of prostaglandin endoperoxide formation in the elevation of cyclic GMP levels during platelet aggregation.

Arachidonic acid- or collagen-induced aggregation was accompanied by a progressive elevation in the level of cyclic GMP in washed human platelets with no significant alteration in the concentration of cyclic AMP. The extent of the increase in cyclic GMP was proportional to the concentration of arachidonic acid added. Enhanced accumulation of cyclic GMP produced by arachidonic or collagen was prevented by prior exposure of platelets to aspirin or indomethacin. Prostaglandin endoperoxide G2 caused platelet aggregation and an increase in cyclic GMP concentration; neither event was blocked by prostaglandin synthesis inhibitors. These results indicate that the generation of prostaglandin endoperoxides is a step in the sequence of events in platelet aggregation leading to the enhanced accumulation of cyclic GMP.

Arachidonic Acids↗

PubMed1976

Scanning and transmission electron microscopic studies of vaginal adenosis and the cervical transformation zone in progeny exposed in utero to diethylstilbestrol.

Much attention has recently been focused on vaginal adenosis and other cervical and vaginal alterations occurring in female offspring exposed to diethylstilbestrol (DES) in utero. These alterations consist of heterotopic glandular epithelium in the vagina, a characteristic cervical transformation zone, and the frequent presence of a cervical collar, or hood. It is believed that these changes occur during embryonic differentiation of the lower genital tract following failure of squamous epithelium to migrate in a cephalad direction to replace columnar epithelium which normally lines the vagina and ectocervix. A number of cases clear-cell carcinoma have occurred in DES-exposed girls who also had adenosis. In an attempt to characterize the cellular populations of these areas of adenosis, we have made an ultrastructural study which is herein reported.

Cervix Uteri↗

PubMed1976

Localization of platelet prostaglandin production in the platelet dense tubular system.

Platelet production of 12L-hydroxy-5,8,10-heptadecatrienoic acid (HHT) and 8-(1-hydroxy-3-oxopropyl)-9, 12L-dihydroxy-5,10-heptadecadienoic acid (PHD), two metabolites of the prostaglandin cyclic endoperoxides PGG2 and PGH2, was found in this investigation to occur primarily in a platelet microsomal fraction consisting almost exclusively of membranes. To further localize the membrane site of platelet prostaglandin biosynthesis, the present study has used a cytochemical technique employing 3,3'-diaminobenzidine as an oxidizable substrate. The reaction product was found to localize in the platelet dense tubular system. Formation of the reaction product was inhibited by aminotriazole. In similar concentrations, aminotriazole inhibited collagen and arachidonic acid aggregation, the second wave of ADP and epinephrine aggregation, but failed to inhibit aggregation by PGG2 and A23187. A study of the mechanism of action of aminotriazole revealed inhibition of formation of HHT and PHD. The results localize platelet prostaglandin biosynthesis to the membranes of the dense tubular system.

Amitrole↗

PubMed1976

Urogenital tract abnormalities in sons of women treated with diethylstilbestrol.

Since in utero exposure to diethylstilbestrol (DES) is known to cause abnormalities of the female genital tract later in life, exposed male offspring were located, surveyed by mail, and compared with unexposed male offspring from the same period and medical practices. The exposed and unexposed respondents appeared comparable and did not differ in their response to most medical questions. However, a larger proportion of exposed than of unexposed boys had experienced problems in passing urine (12.9% vs. 1.8%, P = .0003) and abnormalities of the penile urethra (4.4% vs. 0%; P = .017).

Abnormalities, Drug-Induced↗

PubMed1975

Nuclear scattering applied to radiography.

The possibility of using the nuclear scattering of 500-1000 MeV protons was investigated, in order to obtain direct, three-dimensional reconstruction of an object with only one exposure. The resolution should be about 1 mm3. Preliminary measurements with an incomplete set-up give a resolution of 10 mm3. Additional independent information on the relative concentration of hydrogen compared to other elements should also be obtainable by nuclear scattering radiography. The radiation doses involved are comparable to those of other techniques. The first experimental results are given.

Dose-Response Relationship, Radiation↗

PubMed1974