Vasoactive properties of dihomo-gamma-linolenic acid and series one prostaglandins in a freshwater teleost, Channa maculata

1. Prostaglandins A1, B1, E1 and F1 alpha (2-120 micrograms/kg), arachidonic acid and dihomo-gamma-linolenic acid (0.1-2 mg/kg) were injected intravenously into Channa maculata and changes in arterial blood pressure were recorded. 2. Injection of PGF1 alpha had no significant effect on arterial blood pressure. Injection of PGA1 and PGE1 was followed by dose-dependent hypotension whereas injection of PGB1 elicited significant dose-dependent increase in arterial blood pressure. 3. Both dihomo-gamma-linolenic acid and arachidonic acid were also depressor agents but dihomo-gamma-linolenic acid was more potent. 4. A single bolus intravenous injection of indomethacin (5 mg/kg) or 4 daily intraperitoneal injections (4 x 10 mg/kg) significantly lowered arterial blood pressure. One hour after pre-treatment of indomethacin, the vascular effects of both prostaglandin precursors were abolished. 5. It appears that the vascular effects of prostaglandins in Channa maculata are qualitatively different from those reported for mammals.     

Isolation and chromosomal localization of the human En-2 gene

By low stringency hybridization we have isolated from a human cosmid genomic library sequences homologous with a probe from the Drosophila engrailed gene. Partial nucleotide sequence analysis shows a consensus splice acceptor site followed by an open reading frame (ORF) that can encode 104 amino acids; the first 94 amino acids have 71% identity with the Drosophila engrailed protein. The shared region contains a homeo domain and is within the region of engrailed shared with the Drosophila invected gene and the mouse En-1 and En-2 genes. At the amino acid level, the human sequence is 85% identical with the mouse En-1 gene and 100% identical with the mouse En-2 gene. Hybridization against a panel of human-hamster somatic cell hybrids maps this human En-2 gene to chromosome 7, and regional mapping by in situ hybridization to human chromosomes localizes it to region 7q36 at the end of the long arm.     

Relationship between computerized morphonuclear image analysis and histopathologic grading of breast cancer

A pilot study analyzed the relationship between several morphonuclear parameters and the Bloom-Richardson score for 37 invasive, not-otherwise-specified (NOS) ductal breast carcinomas. The SAM-BA 200 cell image processor and its software were used to measure the nuclear features on Feulgen-stained imprint smears. Two parameters representing the numbers of large and dense chromatin clots and two parameters describing the heterogeneity of the chromatin among nuclei in a specimen evolved in a continuous manner parallel with the Bloom-Richardson score from stages NOS-4 to NOS-8. The systematic measurement of these four parameters on a large series of breast cancers may be able to define an objective and reproducible "scale" of differentiation that could be a helpful tool for pathologists and clinicians.     

Free gp70 from FeLV: enrichment from cell culture fluid by ferric oxide-agarose chromatography

A new chromatographic material based on beads of macroporous crosslinked agarose containing ferric oxide particles was used for enrichment of gp70--the envelope glycoprotein of feline leukemia virus (FeLV). Free gp70 was purified from cell culture fluid in one step with a recovery of 50 to 60% and a purification of about 60 times. The described procedure is a suitable first step for the purification of gp70 from large volumes of cell culture fluid.     

Regulation of urokinase- and tissue-type plasminogen activator gene expression in the rat seminiferous epithelium

The secretion of plasminogen activator by seminiferous tubules at defined stages of the epithelial cycle is influenced both by neighboring spermatogenic cells and by hormones. We have used cRNA probes for urokinase-type (uPA) and tissue-type (tPA) plasminogen activators to analyze their mRNA levels in different stages of the epithelial cycle. Urokinase-type PA mRNA was most abundant in stages VII-VIII, while tPA mRNA levels showed smaller variations between the different stages. Both FSH and (Bu)2cAMP increased the steady-state level of tPA mRNA and tPA production without affecting those of uPA in stages VII-IX in vitro, whereas retinoic acid treatment selectively increased the concentration uPA mRNA and uPA production in stages II-VI. The results show that the expression of the uPA and tPA genes is differentially regulated in specific stages of the rat seminiferous epithelium.     

Measurement of hydrogen peroxide in plasma and blood

Measurement of the oxygen metabolite hydrogen peroxide (H2O2) in biological fluids such as plasma could be of interest because it might indicate participation of toxic oxygen species in tissue injury. Recently several reports claimed to measure H2O2 using spectrophotometric and high pressure liquid chromatographic (HPLC) techniques that utilize oxidation of a substrate to a product by a peroxidase. In such a system it is crucial to perform two control experiments to verify whether the measured substance is H2O2. The specificity of the assay for H2O2 should be checked with catalase, and the degradation of H2O2 or inhibition of the assay system by the sample should be checked by determining the recovery of exogenously added H2O2. We performed both types of controls for HPLC and spectrophotometric determinations of H2O2 in plasma and blood. Our results indicate that contrary to previous reports in the literature the measured substance(s) in plasma or blood is not H2O2. Moreover, quantitative measurements of H2O2 in plasma or blood by HPLC was unreliable due to the irreversible binding of H2O2 to the column surface.     

Expression of phenolic and tyrosyl ring iodothyronine deiodinases in Xenopus laevis oocytes is dependent on the tissue source of injected poly(A)+ RNA

The phenolic (5' position) and tyrosyl (5 position) ring deiodinases which catalyze the peripheral metabolism of thyroid hormones have proven difficult to purify and characterize biochemically. The present studies used Xenopus laevis oocytes as an in vivo translational assay system for detecting and quantitating mRNA for these enzymes. The injection of poly(A)+ RNA prepared from a human term placenta induced 5-deiodinase activity in oocytes. The expressed activity increased for up to 96 h after injection, was proportional to the amount of RNA injected, and manifested a Michaelis-Menten constant (Km) for T3 of 1.6 nM. In oocytes injected with poly(A)+ RNA prepared from rat liver, anterior pituitary gland, or brown adipose tissue, 5-deiodinase activity could not be demonstrated. The injection of poly(A)+ RNA from 15-day-old chick embryonic liver induced both 5'- and 5-deiodinase activity, with the 5'-deiodinase activity being sensitive to inhibition by 6-n-propyl-2-thiouracil. X. laevis oocytes can thus be induced to express either phenolic or tyrosyl ring deiodinase activity, or both, by the microinjection of poly(A)+ RNA prepared from selected tissues. These findings demonstrate that the types of deiodinase activity present in different organs represent tissue specific patterns of mRNA expression and strongly suggest that the enzymes responsible for types I and III deiodinase activity are encoded by different mRNAs.