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Biomedical subjects

J Speck

Publications and source records attributed to J Speck.

14 recordsLinked to original sources
PubMed1992

9-cis retinoic acid stereoisomer binds and activates the nuclear receptor RXR alpha.

Vitamin A (retinol) and its natural derivatives are required for many physiological processes. The activity of retinoids is thought to be mediated by interactions with two subfamilies of nuclear retinoic acid receptors, RAR and RXR. The RARs bind all-trans retinoic acid (t-RA) with high affinity and alter gene expression as a consequence of this direct ligand interaction. RXR alpha is activated by t-RA, yet has little binding affinity for this ligand. t-RA may be converted to a more proximate ligand that directly binds and activates RXR alpha, and we have developed a method of nuclear receptor-dependent ligand trapping to test this hypothesis. Here we report the identification of a stereoisomer of retinoic acid, 9-cis retinoic acid, which directly binds and activates RXR alpha. These results suggest a new role for isomerization in the physiology of natural retinoids.

Animals↗
PubMed1992

The M RNA of impatiens necrotic spot Tospovirus (Bunyaviridae) has an ambisense genomic organization.

The nucleotide sequence of Impatiens necrotic spot virus (INSV) M RNA was determined from cDNA clones. The INSV M RNA was 4972 nucleotides in length with two open reading frames (ORFs) in an ambisense genomic organization. The larger ORF near the 3' end of the viral RNA, coding for a protein with a predicted molecular weight of 124.9 kDa, was in the viral complementary sense and produced the G2 and G1 proteins. A smaller ORF in the viral sense was capable of coding for a 34.1-kDa polypeptide, designated the NSm protein. Two subgenomic RNA species were detected in INSV-infected tissue that corresponded to the predicted sizes (3.3 and 1.0 kb) of the G2-G1 and NSm mRNAs. The ORFs were separated by a 478 nucleotide A-U-rich intergenic region similar to the regions found in other viral RNAs with ambisense ORFs. The intergenic region was predicted to form a stable stem-loop structure (-81.2 kcal/mole). The ambisense genomic organization is characteristic of the S RNA for members of the Phlebovirus, Uukuvirus, and Tospovirus genera in the Bunyaviridae family. This is the first report of an ambisense Bunyaviridae M RNA.

Amino Acid Sequence↗
PubMed1991

Nucleotide sequence of the 3' non-coding region and N gene of the S RNA of a serologically distinct tospovirus.

A tomato spotted wilt-like virus (TSWV-I) is a distinct member of the Tospovirus genus of the Bunyaviridae and is distinguished from the typical TSWV by having a serologically distinct nucleoprotein (N). A cDNA clone extending from the 3' terminus of the viral RNA through the entire N open reading frame (ORF) was sequenced. The TSWV-I N ORF is capable of encoding a polypeptide of 262 amino acids with a predicted Mr of 28.8K. In vitro transcription and translation of the clone produced a protein which comigrated with TSWV-I N and was immunoprecipitated by TSWV-I antibodies. Hybridization analysis of lithium chloride-precipitated RNA from healthy and TSWV-I-infected tissue detected a virus-specific 1.2 kb subgenomic RNA. The TSWV-I S RNA terminal consensus sequence (8 nucleotides) was identical to that of TSWV; the remaining TSWV-I untranslated region showed only 51% identity with that of TSWV. Comparison of the TSWV-I and TSWV N proteins showed 67% identity at the amino acid level. The degree of similarity in the terminal sequence, untranslated region and N ORF is similar to that expected between distinct serogroups within certain genera of the Bunyaviridae.

Amino Acid Sequence↗
PubMed1989

[In vitro parameters for understanding the immunocompetence of chickens of different lineage. 1. The cytotoxicity of avian whole blood against Saccharomyces cells].

A cytotoxicity test was performed as a parameter for the nonspecific defense capacity in chickens using blood and saccharomyces cells (SCT). The test has the special merit of frequent repetitions of the results by two parallel test arrangements. The results of individual animals were not altered during a period of 14 days, as well as relatively not being affected by actual day fluctuation as long as environmental changes or antigenic changes do not appear. The cytotoxic activity is due to cellular defense mechanisms, especially concerning the activity of granulocytes, thrombocytes and monocytes but not lymphocytes and erythrocytes. The lysozyme contents of plasma show a very space cytotoxic activity against saccharomyces cells.

Animals↗
PubMed1989

[In vitro parameters for the comprehension of the immunocompetence of chickens of different lines. 2. Testing an immunocompetent parameter as a selection criterion in the chicken].

A cytotoxicity test using blood and saccharomyces cells (SCT) was experimentally applied in a sample of pedigreed commercial chickens from different lines over 3 generations to test its usefulness as a parameter for the nonspecific defense capacity. The results clearly show a significant difference between the SC rates in the different lines. Positive heritabilities exist between the SC rates of the 3 generations. The correlations between SC rates of males in the first generation and parameters of layer productivity of their daughters are nonsignificant. The possibility to integrate the parameter SC into the selection index is critically discussed.

Animals↗
PubMed1985

Ursodeoxycholic acid treatment of bile reflux gastritis.

Intractable epigastric pain associated with nausea and bilious vomiting often follows gastric surgery and has been attributed to reflux of bile and the irritating effects of endogenous bile acids on the gastric remnant. To test the effect of changing bile acid composition of the refluxed material on the symptoms and gastric mucosal histology, 12 patients with symptomatic alkaline reflux gastritis were treated for 1 mo with placebo and for 1 mo with ursodeoxycholic acid, 1000 mg/day. Before treatment, all patients were symptomatic and manifested epigastric pain, nausea, and bilious vomiting. The gastric mucosa was erythematous, friable, and bile stained, and the histology revealed chronic inflammation. No significant change in symptoms was noted during administration of placebo. In contrast, ursodeoxycholic acid treatment resulted in a profound decrease in the intensity and frequency of pain and almost abolished nausea and vomiting. During bile acid therapy the proportion of ursodeoxycholic acid in gastric bile rose to 50% of total bile acids, whereas cholic and deoxycholic acids decreased and chenodeoxycholic acid remained unchanged. The macroscopic and microscopic appearance of the gastric mucosa, however, did not change after 1 mo of ursodeoxycholic acid treatment. These results suggest that increasing the proportion of ursodeoxycholic acid in refluxed gastric bile reduces the pain and frequency of symptoms associated with bile reflux.

Adult↗
PubMed1985

Lethal atherosclerosis associated with abnormal plasma and tissue sterol composition in sitosterolemia with xanthomatosis.

Tissue sterol composition was determined in an 18-year-old male with sitosterolemia with xanthomatosis who died suddenly and whose coronary and aortic vessels showed extensive atherosclerosis and, for comparison, in an 18-year-old male with minimal atherosclerosis who died accidently. Sterols in the control tissues (plasma, erythrocytes, cardiac muscle, lung, liver, aorta, and brain) contained cholesterol with only trace amounts of cholestanol. In contrast, sterols in corresponding tissues of the sitosterolemic subject (except brain) were composed of cholesterol, increased amounts of plant sterols, campesterol and sitosterol, and 5 alpha-saturated stanols, cholestanol, 5 alpha-campestanol, and 5 alpha-sitostanol, that were deposited in approximately the same ratio as present in plasma. However, sitosterolemic brain sterol composition resembled that of the control brain with cholesterol and only trace amounts (less than 1%) of cholestanol and phytosterols. The sitosterolemic aorta was extensively atherosclerotic and contained more than twice the quantity of sterols as the control aorta (5.6 mg/g versus 2.6 mg/g) with increased amounts of cholesterol, plant sterols, and 5 alpha-saturated stanols. These results indicate that cholesterol, plant sterols, and 5 alpha-stanols are deposited prematurely and are associated with accelerated atherosclerosis in subjects with sitosterolemia with xanthomatosis.

Adolescent↗