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Biomedical subjects

E C Schmidt

Publications and source records attributed to E C Schmidt.

14 recordsLinked to original sources
PubMed1984

Circumsporozoite gene of plasmodium cynomolgi (Gombak):cDNA cloning and expression of the repetitive circumsporozoite epitope.

We report the identification, sequence, and expression in Escherichia coli of the immunodominant epitope of the circumsporozoite (CS) gene of Plasmodium cynomolgi (Gombak), a simian malaria parasite. This epitope is encoded by a DNA sequence that is tandemly repeated 10 times in the cDNA clone. Subclones that contain and express only repeats and in variable number have been constructed. We show that the binding of a specific anti-CS protein monoclonal antibody correlates positively with the number of repeats in each subclone. The CS gene of another strain of P. cynomolgi (NIH) encodes an immunodominant epitope that is immunologically distinct from that of the Gombak strain. We present evidence that these two CS genes share extensive overall homology, although the nucleotide sequences that encode the epitopes appear to be unrelated.

Animals↗
PubMed1984

Mechanisms of resistance to the intracellular protozoan Encephalitozoon cuniculi in mice.

Mechanisms of resistance to the obligate intracellular protozoan Encephalitozoon cuniculi were studied in BALB/c mice. Resistance to lethal disease was T cell-dependent because transfer of T-enriched, but not T-depleted, spleen cells from sensitized BALB/c donors would protect infected BALB/c-nu mice. A modified focus-forming assay was utilized to measure effects on E. cuniculi infectivity in vitro. The results show that antibodies exert an opsonization effect and may block parasite entry into nonphagocytic cells. No cytotoxic T cells were demonstrated. Supernatants from E. cuniculi-sensitized spleen cells incubated with E. cuniculi in vitro could induce adherent PEC to kill E. cuniculi.

Animals↗
PubMed1983

Status of the major epicardial coronary arteries 80 to 150 days after percutaneous transluminal coronary angioplasty. Analysis of 3 necropsy patients.

Certain clinical and necropsy cardiac findings are described in 3 men who had percutaneous transluminal coronary angioplasty (PTCA) of the left anterior descending (LAD) coronary artery 80, 90, and 150 days before sudden death. Each patient had a decrease in the mean transstenotic coronary gradient (17, 38, and 43 mm Hg) and an angiographic increase in the LAD luminal diameter (55, 60, and 65%). At necropsy, the LAD coronary artery in the area of the PTCA in each patient was narrowed 76 to 95% in cross-sectional area by atherosclerotic plaques. No cracks in plaques or other lesions which may have resulted from the PTCA procedure were identified histologically in the LAD coronary artery of any patient.

Adult↗
PubMed1983

Murine encephalitozoonosis model for studying the host-parasite relationship of a chronic infection.

Encephalitozoon cuniculi caused chronic nonlethal infections in euthymic BALB/cAnN mice, whereas athymic BALB/cAnN-nu mice died from infection. Specific, anamnestic, transferable, and acquired responses against E. cuniculi were expressed by infected euthymic mice. Resistance to lethal disease appears to be T-cell dependent. Immune serum failed to protect infected athymic mice, whereas the transfer of T-enriched spleen cells from E. cuniculi-sensitized euthymic donors prevented lethal E. cuniculi infections in athymic mice. These findings indicate that murine encephalitozoonosis may be an excellent system for studies of a chronic infection in an immunologically well-characterized host.

Animals↗
PubMed1976

Hormone-induced alterations in nonhistone protein. Methylation and phosphorylation in Sciara coprophila.

Methylation and phosphorylation of chromosomal nonhistone protein (NHP) has been demonstrated in the salivary gland cells of diptera [5, 7] and implicated in the control of gene expression [35, 36]. Furthermore, hormones can stimulate methyl and phosphoryl side chain metabolism and thus enhance template activity. Salivary glands from late fourth instar female larvae of Sciara coprophila (cortisone-supplemented and normal diet) were incubated in 3H-uridine (10 muCi/ml), 3H-thymidine (10 muCi/ml), 3H-methyl-methionine (20 muCi/ml), 35S-methionine (10 muCi/ml) and 32P-orthophosphate (1 mc/ml), for varying time periods, to measure RNA synthesis, DNA synthesis, methylation, protein synthesis and phosphorylation, respectively. Following selective extraction of lipid, histone and nucleic acids, glands were prepared for light microscope autoradiography. A more specific labelling pattern, as well as increased grain number on particular bands, interbands and bulbs, was noted on chromosomes from cortisone-fed larvae incubated in 3H-methyl-methionine for 1 min when compared with larvae on the standard diet. Cortisone also increased RNA synthesis and nucleoprotein phosphorylation, but not DNA or protein synthesis. In summary, cortisone enhances the specificity and degree of NHP methylation and phosphorylation at discrete chromosomal loci, i.e. alterations in side chain metabolism which may be responsible for increased RNA synthesis.

Animals↗
PubMed1976

The effect of ecdysterone on nonhistone proteins in salivary gland chromosomes of Sciara coprophila.

Synthesis and transport of proteins to the cell nucleus during puff induction was studied in S. coprophila. Changes in grain distribution along chromosomes (L-methionine [35S] incorporation into protein) were correlated with puffs induced by ecdysterone in vitro; A pattern of specific labelling at the sites of incipient puffs was noted within 2 h after the addition of the hormone, i.e. grains on the chromosomes were in clusters, characteristic for this time point and not seen in the controls (where only non-specific labeling was noted 0-4 h). Characteristic chromosomal puffs appeared between 3-4 h after the addition of ecdysterone. It was concluded that during ecdysterone-induced puff formation in salivary gland chromosomes, proteins which had been previously synthesized were selectively transported from the cytoplasm to specific sites on the chromosomes.

Animals↗