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Biomedical subjects

D Horn

Publications and source records attributed to D Horn.

At least 145 records · Page 8Linked to original sources
PubMed1980

Xiphopagus conjoined twins: a 300-year review of the obstetric, morphopathologic, neonatal, and surgical parameters.

Obstetric, morphopathologic, neonatal, and surgical features of 36 reported cases of xiphopagus conjoined twins were correlated and reveal: (1) a 6% incidence of prenatal diagnosis; (2) a 36% rate of dystocia; (3) a 19% incidence of stillbirths; (4) variation in the extent of fusion; (5) a high rate of occurrence of concurrent congenital malformations, not limited to a conjoined area, especially of the heart (25%) and gastrointestinal tract (33%); (6) the importance of diagnostic tests to elucidate conjoined or abnormal structures because of the high rate of concurrent malformations; (7) opisthotonos as the body alignment position of choice; (8) a 69% female sex bias; (9) surgical separation usually in the first year of life; and (10) a 53% survival rate. This paper correlates the world literature for xiphopagus conjoined twins for the past 300 years.

Abnormalities, Multiple↗
PubMed1980

Steroid hormone receptor studies in melanoma model systems.

The transplantable B-16 melanotic melanoma carried in syngeneic C57Bl/6J female mice and the Syrian hamster melanoma cell line, RPMI 3460, were utilized to determine whether steroid-hormone receptors are present in animal melanomas. In the B-16 melanoma, a cytoplasmic-estrogen receptor is detectable, but there is no evidence for androgen or progestin receptors. Some tumors contain a glucocorticoid-binding macromolecule. Sucrose-density gradient centrifugation of cytosol after incubation with [3H]-estradiol revealed an 8S peak that was suppressed by excess radioinert diethylstilbesterol. Binding varied from 5-35 fmoles per mg cytosol protein. Scatchard analysis of [3H]-estradiol binding in cytosol yielded a single class of high-affinity binding sites; the dissociation constant is 6 x 10(-10) M. The receptor molecule is shown to be estrogen-specific by ligand competition assays. In contrast to B-16 melanoma, no estrogen, androgen, or progestin receptor can be found in the Syrian hamster melanoma cell line. However, a substantial level of specific binding is observed using [3H]-dexamethasone. Sucrose-gradient centrifugation of cytosol from this cell line after incubation with [3H]-dexamethasone revealed a 7S peak that was suppressed by excess radioinert dexamethasone. Scatchard analysis indicated a single class of high-affinity sites with a dissociation constant of 2 x 10(-9) M. Binding levels from 70-610 fmoles per mg cytosol protein were observed. The Syrian hamster melanoma cells also exhibit a biological response to glucocorticoids: Dexamethasone causes both an inhibition of growth and a decrease in final-cell density in these cells.

Animals↗
PubMed1980

Sequential scintiangiography of the hepato-splenic system of xiphopagus conjoined twins.

Scintiangiography of xiphopagus conjoined twins following sequential i.v. injection of Tc-99m sulfur colloid revealed the size, configuration, and anatomic point of fusion of the twins' common liver prior to surgery. Cross circulation was determined to be non-significant by this approach. The technique is presented, compared to other methods, and the benefit of sequential hepatic scintiangiography for xiphopagus conjoined twins is reviewed.

Cross Circulation↗
PubMed1980

Receptor for glucocorticoids in RPMI 3460 melanoma cells.

We are investigating the role of steroid hormones in the biological behavior of malignant melanoma. We have recently shown that the growth of RPMI 3460 Syrian hamster melanoma cells in monolayer culture is retarded by the synthetic glucocorticoid dexamethasone. This paper reports the identification of a macromolecule with properties of a glucocorticoid receptor in cytosis prepared from these cells. Sucrose density gradient analyses on six separate cell batches consistently demonstrated substantial levels of saturable [3H]dexamethasone binding [concentration = 195 +/- 47 (S.E.) fmol/mg cytosol protein] in the 7S region of the gradients. Similar analyses failed to detect saturable binding for other classes of steroid hormones. Scatchard plots of [3H]dexamethasone binding to the receptor were linear, indicating a single class of high-affinity sites (Kd = 2.3 +/- 0.78 x 10(-9) M for three cell batches). Steroid competition experiments confirmed the glucocorticoid specificity of the binding molecule; competitors in descending order of effectiveness were glucocorticoids, mineralocorticoid, progestins, estrogen, and androgen. Combined hormone receptor and growth studies with RPMI 3460 cells can help to define the mechanism of glucocorticoid action in malignant melanoma and may ultimately help establish the value of steroid hormones as therapeutic agents for this disease.

Androgens↗
PubMed1979

A survey of intraocular pressures with emphasis on patients under ten years of age.

This paper presents the results of a cross-sectional survey of intraocular pressures in patients of the University Optometric Center, the clinical facility of the State College of Optometry, SUNY. The study consisted of two parts: a pilot study conducted by one of the authors and a survey of patient records that were reviewed at random with particular emphasis on patients under 10. The results indicate that the intraocular pressure norms used to evaluate the general population are also appropriate for evaluation of patients under 10 years of age.

Adolescent↗
PubMed1979

An embedded contact lens in the upper lid masquerading as a mass.

A patient who "lost" his right contact lens three years prior to our examination was found to have a mass in the right upper lid which contained the hard contact lens. A careful search of the superior fornix and the upper lid, with double eversion of the lids, is indicated in instances where a patient presents reporting loss of a lens he was wearing or inserting.

Adult↗
PubMed1979

Effectiveness of measures against smoking.

The objective of a program to control cigarette smoking is to reduce illness and early mortality. This requires a) reducing the taking up of smoking, b) increasing the giving up of smoking, c) reducing the dosage of harmful substances received by the smoker, and d) protecting the non-smoker. Such a program requires both an educational effort and a management approach. The success of past educational efforts has changed the nature of current efforts from an emphasis on persuading people to stop smoking to an emphasis on encouraging those who have been unsuccessful to try again, to assist them, and to use dosage reduction as an alternative to quitting. Managerial efforts most promising are the gradual reduction of harmful substances in the smoke, economic disincentives, and limitations of smoking in public places, thereby protecting both the smoker and the non-smoker.

Adolescent↗
PubMed1977

DNA binding and uptake by nuclei isolated from plant protoplasts: factors affecting DNA binding and uptake.

DNA binding and uptake by nuclei isolated from soybean (Glycine max L. Merr.) protoplasts were investigated using radioactive homogeneous DNA prepared from soybean cells. DNA binding to nuclei was found to decrease drastically with increased incubation time. Total uptake and acid-precipitable uptake reached a maximum after 20 minutes of incubation. Optimum DNA binding and uptake occurred at pH 6 and the process was enhanced by increasing the incubation temperature to 40 C. Salmonella typhimurium DNA and poly ([dA-dT]-[dA-dT]) competitively inhibited DNA binding whereas calf thymus DNA was less competitive; however, Micrococcus lysodeikticus DNA stimulated DNA binding and tobacco mosaic virus RNA had no effect. DNA binding and uptake was enhanced by addition of Mg ions, Ca ions, poly-l-lysine, and ATP. Increasing amounts of EDTA appeared to decrease DNA binding. Pronase strongly inhibited DNA binding and uptake.

Journal Article↗
PubMed1977

A rapid, simple method for nuclei isolation from plant protoplasts.

A rapid, simple method for nuclei isolation and purification from soybean (Glycine max L. Merr.) protoplasts is described. The isolated nuclei exhibited active amino acid incorporation and RNA synthesis, but DNA synthesis was not detectable. Analysis by CsCl density gradient centrifugation showed that DNA isolated from nuclei had a single band, while DNA isolated from protoplasts consisted of three bands comprised of nuclear DNA, mitochondrial DNA, and chloroplast DNA.

Journal Article↗
PubMed1976

Inhibition of biological effects of bromodeoxyuridine by deoxycytidine: correlation with decreased incorporation of bromodeoxyuridine into DNA.

The effects of 5-bromodeoxyuridine (BrdU) on pigmentation, contact inhibition, cell morphology, and tumorogenicity of Syrian hamster melanoma cells are inhibited in the presence of deoxycytidine (dC). The inhibition of these biological effects of BrdU by dC is correlated with a decrease in the incorporation of BrdU into nuclear DNA. The results suggest that the intracellular changes resulting from the addition of dC to cells in the presence of BrdU are comparable to those resulting from a decrease in the concentration of BrdU in the medium.

Animals↗
PubMed1975

Requirement of bromodeoxyuridine for the maintenance of "transformed" characteristics in bromodeoxyuridine dependent cells.

A bromodeoxyuridine(BUdr) dependent cell line, called B4, Which requires BUdr not only for optimal growth but also for the maintenance of the non-contact inhibited state was described previously. We have now shown that contact inhibition in the B4 cells in the absence of BUdr is associated with a marked decrease in the percent of cells synthesizing DNA. The transition to the contact inhibited state in the absence of BUdr does not seem to be due to changes in cyclic AMP levels. It has also been shown that several but not all of the characteristics which distinguish transformed from untransformed cells also distinguish B4 cells grown in the presence of BUdr from B4 cells grown in the absence of BUdr. In addition to being contact inhibited, B4 cells grown in the absence of BUdr have a higher serum requirement, grow less well in soft agar, and are less agglutinable by wheat germ agglutinin than B4 cells grown in the presence of BUdr. Agglutinability by concanavalin A, however, is the same for B4 cells grown in the presence and absence of BUdr. Dependent cells maintained in the presence of BUdr do not form tumors and it is not yet clear how the transformed characteristics of the dependent cells are related to malignancy.

Agglutination Tests↗
PubMed1974

Reversible "transformation" of bromodeoxyuridine-dependent cells by bromodeoxyuridine.

The growth characteristics of a bromodeoxyuridine-dependent cell line that was derived from a non-contact-inhibited Syrian hamster melanoma line were studied. The dependent cells require high concentrations of bromodeoxyuridine not only for optimal growth but also for the maintenance of the non-contact-inhibited state. When grown in the absence of bromodeoxyuridine, the dependent cells become contact-inhibited. The transition to the contact-inhibited state is reversed when bromodeoxyuridine is added back to the medium, if the bromodeoxyuridine is incorporated into dividing cells. The effects of bromodeoxyuridine on growth rate and on contact inhibition are separable.

Animals↗
PubMed1973

Development of a quantitative immunological assay for the study of spore coat synthesis and morphogenesis.

A quantitative assay employing (125)I-labeled antibody has been developed for Bacillus cereus T spore coat protein. Populations of antibody molecules with various affinities for inner or outer coat can be prepared by selective adsorption to and elution from different coat preparations. Adsorption to and elution from intact spores results in an antibody preparation at least 15 times more reactive to outer coat. This antibody is useful for measuring the time and extent of spore coat maturation, i.e., outer spore coat formation. Rifampin inhibits the increase in content of this coat antigen.

Adsorption↗