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Biomedical subjects

R J Schmidt

Publications and source records attributed to R J Schmidt.

At least 91 records · Page 5Linked to original sources
PubMed1986

Encapsulated follicular carcinoma of the thyroid: diagnosis, treatment, and results.

Nineteen cases of encapsulated follicular carcinoma of the thyroid treated at the Massachusetts General Hospital from 1962 to 1979 are reviewed. In all patients the encapsulated nodules had histologic evidence of capsular or vascular invasion. There were 13 women and six men with ages ranging from 14 to 74 years. Eight of the 19 patients underwent large-needle thyroid biopsies before surgery, and in each patient a hypercellular lesion was identified requiring surgery to exclude malignancy. The operative approach was ipsilateral lobectomy with removal of sufficient thyroid tissue to assure that resection margins were free of disease. The size of the tumors ranged from 2 to 6.5 cm in greatest diameter. The mean follow-up was 112 months. Three patients developed ipsilateral neck recurrences. Four patients developed metastases to the bone, brain, or lung. The time from initial operation to recurrence or metastasis ranged from 0 to 241 months (mean, 69 months). There was a 5-year survival rate of 88% and a 10-year survival rate of 78%. Only two of the six patients with complete follow-up died of thyroid malignancy. Of the 16 patients with recurrent or metastatic disease, two died of the disease. No patient whose lesion was 3 cm or smaller developed metastases or recurrences, and of the 10 patients with lesions 3.5 cm or larger, six developed metastatic or recurrent disease. Age was also a prognostic factor, since four of the six patients over 60 years old developed recurrent or metastatic disease.

Adenocarcinoma↗
PubMed1985

The structure and evolution of a 461 amino acid human protein C precursor and its messenger RNA, based upon the DNA sequence of cloned human liver cDNAs.

Human liver cDNA coding for protein C has been synthesized, cloned and sequenced. The abundance of protein C message is approximately 0.02% of total mRNA. Three overlapping clones contain 1,798 nucleotides of contiguous sequence, which approximates the size of the protein's mRNA, based upon Northern hybridization. The cDNA sequence consists of 73 5'-noncoding bases, coding sequence for a 461 amino acid nascent polypeptide precursor, a TAA termination codon, 296 3'-noncoding bases, and a 38 base polyadenylation segment. The nascent protein consists of a 33 amino acid "signal", a 9 amino acid propeptide, a 155 amino acid "light" chain, a Lys-Arg connecting dipeptide, and a 262 amino acid "heavy" chain. Human protein C and Factor IX and X precursors possess about one third identical amino acids (59% in the gamma-carboxyglutamate domain), including two forty-six amino acid segments homologous to epidermal growth factor. Human protein C also has similar homology with prothrombin in the "leader", gamma-carboxyglutamate and serine protease domains, but lacks the two "kringle" domains found in prothrombin.

Amino Acid Sequence↗
PubMed1985

When is a chrysanthemum dermatitis not a chrysanthemum dermatitis? The case for describing florists' chrysanthemums as Dendranthema cultivars.

In order to provide a new reference point in the dermatological literature from which the naming of florists' chrysanthemums may be regularised and standardised, the case is presented for the use of the generic name Dendranthema together with a cultivar name in place of a specific epithet. A review of cultivar specificity in chrysanthemum dermatitis is also presented.

Dermatitis, Contact↗
PubMed1985

Processing of the precursor to a chloroplast ribosomal protein made in the cytosol occurs in two steps, one of which depends on a protein made in the chloroplast.

In pulse-chase experiments in which log-phase cells of Chlamydomonas reinhardtii were labeled in vivo for 5 min with H2(35)SO4, fluorographs of immunoprecipitates from whole cell extracts revealed that chloroplast ribosomal proteins L-2, L-6, L-21, and L-29, which are made in the cytosol and imported, appeared in their mature forms. However, in the case of chloroplast ribosomal protein L-18, which is also made in the cytoplasm and imported, a prominent precursor with an apparent molecular weight of 17,000 was found at the end of a 5-min pulse. This precursor was processed to its mature size (apparent molecular weight of 15,500) within the first 5 min of the subsequent chase. As determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the precursor to L-18 formed in vivo was 1.5 kilodaltons smaller than the primary product detected in translations of Chlamydomonas polyadenylated RNA in vitro. Upon a 10-min incubation with a postribosomal supernatant from Chlamydomonas, the 18,500-dalton precursor detected in vitro could be partially converted into a polypeptide that comigrated with the 17,000-dalton precursor detected in extracts of cells labeled in vivo. Under conditions in which the total amounts of chloroplast proteins had been reduced and cells were made to synthesize ribosomes rapidly, the apparent half-life of the 17,000-dalton precursor was extended over that seen in log-phase cells. When chloroplast protein synthesis was inhibited with lincomycin for 3 h before labeling under these conditions, the 17,000-dalton L-18 precursor but not the mature form was found, and the precursor was slowly degraded during a 60-min chase. When cells were placed in the dark for 3 h before labeling, processing of this precursor to the mature form appeared unaffected, but the chloroplast-synthesized ribosomal protein L-26 was detected, indicating that chloroplast protein synthesis was still occurring. We interpret these results to indicate that the maturation of protein L-18 in vivo involves at least two processing steps, one of which depends on a protein made on chloroplast ribosomes.

Chlamydomonas↗
PubMed1984

Expression of prokaryotic genes for hygromycin B and G418 resistance as dominant-selection markers in mouse L cells.

Novel bacterial resistance genes were cloned and expressed as dominant selection markers in mammalian cells. Escherichia coli genes coding for resistance to the aminocyclitol antibiotics hygromycin B (Hm) and G418 were cloned into the eukaryotic expression plasmid pSV5GPT [Mulligan and Berg, Proc. Natl. Acad. Sci. USA 78 (1981) 2072-2076]. Mouse cells normally sensitive to 100 micrograms/ml Hm were transformed with these plasmids and selected in 200 micrograms/ml Hm. Transformants resistant to as much as 1 mg/ml Hm and 500 micrograms/ml G418 were isolated. Cell extracts contained an acetyltransferase activity capable of acetylating G418 and an Hm aminocyclitol phosphotransferase activity. Plasmid DNA sequences were identified by Southern blot analysis of high Mr DNA isolated from transformed cells.

Acetyltransferases↗
PubMed1984

Chloroplast ribosomal proteins of Chlamydomonas synthesized in the cytoplasm are made as precursors.

Polyadenylated RNA from Chlamydomonas was translated in a cell-free rabbit reticulocyte system that employed [35S]methionine. Antibodies made to four chloroplast ribosomal proteins synthesized in the cytoplasm and imported into the organelle were used for indirect immunoprecipitation of the labeled translation products, which were subsequently visualized on fluorographs of SDS gels. The cytoplasmically synthesized chloroplast ribosomal proteins were first seen as precursors with apparent molecular weights of 1,000 to 6,000 greater than their respective mature forms. Processing of the ribosomal protein precursors to mature proteins was affected by adding a postribosomal supernatant that had been extracted from cells of Chlamydomonas. In contrast to the chloroplast ribosomal proteins synthesized in the cytoplasm, two such proteins made within the chloroplast were found to be synthesized in mature form in cell-free wheat germ translation systems programmed with nonpolyadenylated RNA.

Animals↗
PubMed1984

Immunological similarities between specific chloroplast ribosomal proteins from Chlamydomonas reinhardtii and ribosomal proteins from Escherichia coli.

Polyclonal antibodies were elicited against seven of the 33 different proteins of the large subunit of the chloroplast ribosome from Chlamydomonas reinhardtii. Three of these proteins are synthesized in the chloroplast and four are made in the cytoplasm and imported. In western blots, six of the seven antisera are monospecific for their respective large subunit ribosomal proteins, and none of these antisera cross-reacted with any chloroplast small subunit proteins from C. reinhardtii. Antisera to the three chloroplast-synthesized ribosomal proteins cross-reacted with specific Escherichia coli large subunit proteins of comparable charge and molecular weight. Only one of the four antisera to the chloroplast ribosomal proteins synthesized in the cytoplasm cross-reacted with an E. coli large subunit protein. None of the antisera cross-reacted with any E. coli small subunit proteins. On the assumption of a procaryotic, endosymbiotic origin for the chloroplast, those chloroplast ribosomal proteins still synthesized within the organelle appear to have retained more antigenic sites in common with E. coli ribosomal proteins than have those which are now the products of cytoplasmic protein synthesis. Antisera to this cytoplasmically synthesized group of chloroplast ribosomal proteins did not recognize any antigenic sites among C. reinhardtii cytoplasmic ribosomal proteins, suggesting that the genes for the cytoplasmically synthesized chloroplast ribosomal proteins either are not derived from the cytoplasmic ribosomal protein genes or have evolved to a point where no antigenic similarities remain.

Biological Evolution↗
PubMed1984

Testing with musk ambrette and congeners in a case of photosensitivity dermatitis and actinic reticuloid syndrome (PD/AR).

The response of a patient with the PD/AR syndrome to patch and photopatch testing with musk ambrette, musk ketone, and musk xylol was investigated. In addition, solutions of these nitro-musks were allowed to photodecompose prior to patch and photopatch testing. Only the photopatch tests with musk ambrette and with the photodecomposed musk ambrette gave positive results. The results do not provide support for the hypothesis that photocontact allergy to musk ambrette is in fact a contact allergy to a photodecomposition product of musk ambrette.

Dinitrobenzenes↗
PubMed1983

Sites of synthesis of chloroplast ribosomal proteins in Chlamydomonas.

Cells of Chlamydomonas reinhardtii were pulse-labeled in vivo in the presence of inhibitors of cytoplasmic (anisomycin) or chloroplast (lincomycin) protein synthesis to ascertain the sites of synthesis of chloroplast ribosomal proteins. Fluorographs of the labeled proteins, resolved on two-dimensional (2-D) charge/SDS and one-dimensional (1-D) SDS-urea gradient gels, demonstrated that five to six of the large subunit proteins are products of chloroplast protein synthesis while 26 to 27 of the large subunit proteins are synthesized on cytoplasmic ribosomes. Similarly, 14 of 31 small subunit proteins are products of chloroplast protein synthesis, while the remainder are synthesized in the cytoplasm. The 20 ribosomal proteins shown to be made in the chloroplast of Chlamydomonas more than double the number of proteins known to be synthesized in the chloroplast of this alga.

Anisomycin↗
PubMed1983

The dermatitic properties of black bryony (Tamus communis L.).

The skin irritant properties of both the juice expressed from the ripe berries and the slimy mucilage present in the rhizomes of black bryony (Tamus communis L.) were investigated. The dermatitis produced on human skin after gently rubbing in either the berry juice or the rhizome mucilage was found in both cases to be a result of mechanical irritation, being produced by penetration of the skin by minute needle-like crystals of calcium oxalate. Scanning electron micrographs supporting this conclusion are presented. Chemical investigation of the rhizome mucilage confirmed the presence of histamine. The rôle of histamine in the production of skin irritation following contact with the rhizome mucilage is discussed.

Calcium Oxalate↗
PubMed1981

Insulin synthesis in a clonal cell line of simian virus 40-transformed hamster pancreatic beta cells.

A clonal hamster beta cell line (HIT) was established by simian virus 40 transformation of Syrian hamster pancreatic islet cells. Cytoplasmic insulin was detected in all cells by indirect fluorescent antibody staining, and membrane-bound secretory granules were observed ultrastructurally. Acidified-ethanol extracts of HIT cell cultures contained hamster insulin as determined by radioimmunoassay, radioreceptor assay, and bioassay. One subclone at passage 39 contained 2.6 micrograms of insulin per mg of cell protein. [3H]Leucine-labeled HIT insulin and proinsulin were identical to islet-derived proteins when compared by NaDodSO4/polyacrylamide gel electrophoresis of immunoprecipitates. HIT cell insulin secretion was stimulated by glucose, glucagon, and 3-isobutyl-1-methylxanthine. Insulin secretion at optimal glucose concentration (7.5 mM) was 2.4 milliunits per 10(6) cells per hr. Somatostatin and dexamethasone markedly inhibited HIT insulin secretion. The HIT cell line represents a unique in vitro system for studying beta cell metabolism and insulin biosynthesis.

Animals↗
PubMed1980

Skin irritant effects of esters of phorbol and related polyols.

The skin irritant potencies of several naturally occurring and semi-synthetic polyfunctional esters based on the tigliane hydrocarbon skeleton were studied using a mouse ear irritancy assay. The compounds used were esters of 12-deoxyphorbol, 12-deoxy-16-hydroxyphorbol, and phorbol. Observations were also made on the time interval between application of these compounds in acetone solution to the mouse ear, and the attainment of maximum response. Structure/activity relationships are discussed and compared with previous observations on the skin irritant potencies of esters based on the closely related daphnane hydrocarbon skeleton. The possible nature of the site of action in the target membrane is also discussed.

Alcohols↗
PubMed1980

Skin irritants of the sun spurge (Euphorbia helioscopia L.).

Euphorbia helioscopia is a common herbaceous week found in the British Isles and parts of Europe. It has been responsible for poisoning of livestock resulting in severe inflammation particularly of mucous membranes and the eyes. Four esters of 12-deoxyphorbol were isolated from the fresh aerial parts of the plant and their irritant doses 50% (I.D.50) ascertained using female L.A.C.A. mice, 12-Deoxyphorbol-13-phenylacetate-20-acetate was found to be the major component of the toxic fraction and occurred in yields of 0.0012% w/w. This compound was also the most irritant substance isolated and exhibited an I.D.50 of 0.038microgram, and is accordingly considered to be responsible for the major part of the toxicity of E. helioscopia. A high molecular weight aliphatic ester, 12-deoxyphorbol-13-dodecdienoate-20-acetate, was also obtained in low yields. This compound exhibited an I.D.50 of 0.12microgram. The final two esters obtained from the toxic fraction of the plant were the low molecular weight homologues, 12-deoxyphorbol-13-[2-methyl-cis-2-butenoate]-20-acetate and 12-deoxyphorbol-13-[2-methyl-cis-2-butenoate]. These compounds exhibited I.D.50 of 3.09 and 0.72 microgram, respectively and were the least irritant of the series of compounds isolated.

Animals↗
PubMed1979

An assay procedure for the comparative irritancy testing of esters in the tigliane and daphnane series.

A method is described for testing of diterpene esters for irritancy. The technique involves the application of acetone solutions of the toxins to the inside ears of female LACA mice. The number of mice responding per group and the log10 dose data were evaluated using probit analysis with the assistance of a computer program. This evaluation has the advantage that approximations inherent with an arithmetical evaluation were eliminated, and limits may be placed upon the standard deviation of the irritant dose 50% (ID50). In addition, the use of a chi2 test automatically eliminated results which were not attributed to random biological variation. Observations of the time to onset and the persistence of the inflammation have led to the suggestion that daphnane orthoester diterpenes may elicit their effect by means of a direct action at a receptor site in skin, whereas the tigliane O-acyl esters may in part act by causing more general tissue damage.

Animals↗