Role of leukotrienes in the genesis and healing of water immersion stress-induced gastric ulcers in rats

We investigated the role of leukotrienes (LTs) in the genesis of water immersion stress-induced gastric ulcers. Peptide LTs were detected after 4 h stress (3.7 +/- 0.5 ng/g tissue), although they were not detected after 2 h stress, and considerable amounts (20.3 +/- 2.3 ng/g tissue) were detected after 6 h stress. In contrast, AA-861 (100 mg/kg, p.o.), a 5-lipoxygenase inhibitor, reduced ulcer indices significantly after 6 h stress, although no significant changes were observed after 2 or 4 h stress compared with the control group. Peptide LTs were not detected after 4 h and those detected after 6 h stress were remarkably reduced by AA-861 treatment. The role of LTs in the healing of water immersion stress-induced gastric ulcers was also investigated. Significant ulcer healing was not observed within 24 h after stress but was significantly recovered after 48 h. Peptide LTs decreased time-dependently and 48 h after treatment they were not detected. In the rats treated with AA-861, ulcer indices and peptide LTs levels were remarkably reduced after 12 h, concomitantly. These results suggest that the increase in mucosal peptide LTs might be an inhibitory factor to ulcer healing.     

Mitochondrial DNA mutations in mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS)

The total sequences of mitochondrial DNA were determined in two patients with juvenile-onset mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) due to Complex I deficiency. Patients 1 and 2 had three and two unique point mutations, respectively, causing replacement of phylogenically conserved amino acids. A transition from G to A was found at nucleotide position 5601 in the alanine tRNA gene of Patient 2, and a transition from A to G was found at 3243 in the leucine (UUR) tRNA gene of both patients. The latter mutation located at the phylogenically conserved 5' end of the dihydrouridine loop of the tRNA molecule, and was present in two patients with adult-onset MELAS and absent in controls. These results indicate that a mass of mtDNA mutations including the A-to-G transition in the tRNA(Leu) gene is a genetic cause of MELAS.     

H+ uptake increases GTP-induced connection of inositol 1,4,5-trisphosphate- and caffeine-sensitive calcium pools in pancreatic microsomal vesicles.

Evidence suggests that GTP but not GTP gamma S activates Ca2+ movement between myo-inositol 1,4,5-trisphosphate (IP3)-sensitive and -insensitive Ca2+ pools (1). Measuring 45Ca2+ uptake into pancreatic microsomal vesicles we have determined the sizes of three different Ca2+ pools which release Ca2+ in response 1) to IP3, 2) to caffeine, and 3) to both IP3 and caffeine ("common" Ca2+ pool). In the presence of GTP the size of the IP3-sensitive Ca2+ pool is decreased whereas the "common" Ca2+ pool is increased as compared to control Ca2+ pool sizes in the presence of GTP gamma S. This effect of GTP is inhibited by bafilomycin B1, a specific inhibitor of vacuolar type H+ ATPases (2). We conclude that GTP induced connection between IP3- and caffeine-sensitive Ca2+ pools is triggered by intravesicular acidification and involves function of small GTP-binding proteins, known to mediate interorganelle transfer.     

Isolation of a hagfish gene that encodes a complement component.

It has been widely accepted that cyclostomes are the most primitive vertebrates extant with the ability to produce antibodies. We isolated cDNA clones that encode a putative 'antibody' from one of the cyclostomes, Eptatretus burgeri. The amino acid sequence predicted from the nucleotide sequences of the cDNA clones indicated that this gene does actually encode the proteins isolated as hagfish 'antibodies' by various investigators. However, these proteins are not similar to mammalian immunoglobulins but have some characteristics common to complements C3, C4 and C5 in higher vertebrates. We discuss the relationships of the isolated gene for hagfish complement with the mammalian genes for complements C3, C4 and C5. We also discuss the possibility of the presence of antibodies in cyclostomes.     

cDNA cloning of the hydroxysteroid sulfotransferase STa sharing a strong homology in amino acid sequence with the senescence marker protein SMP-2 in rat livers

A cDNA encoding hydroxysteroid sulfotransferase a (STa), which catalyzes activation of carcinogenic polycyclic hydroxymethyl-arenes, was isolated from a lambda gtll cDNA expression library constructed from poly(A)+RNA of a female Sprague-Dawley (SD) rat liver. The cDNA, designated as ST-40, consisted of 1,015 base pairs which had an open reading frame of 852 base pairs encoding the entire rat STa subunit of 284 amino acids. The nucleotide base sequence of the ST-40 cDNA shared a strong homology of 94.4% with that of ST-20 cDNA encoding a hydroxysteroid ST which had been reported by us. The deduced amino acid sequence of STa had a homology of 73.7% with that of an SD rat liver senescence marker protein (SMP-2) consisting of 282 amino acid residues. However, STa was found to share a much stronger homology of 92% on the average with SMP-2 in their four specific regions corresponding to about 60% of the total sequences, indicating SMP-2 to be an isozyme of hydroxysteroid ST.     

Plasma growth hormone, insulin-like growth factor-I, and milk production responses to exogenous human growth hormone-releasing factor analogs in dairy cows

Responses of plasma growth hormone (GH) and insulin-like growth factor-I (IGF-I), and milk production to subcutaneous (sc) injection(s) of two synthetic human growth hormone-releasing factor (hGRF) analogs were studied in dairy cows. Two mg of each hGRF analog dissolved in 5 ml saline per cow were injected into the shoulder area of each experimental animal, and jugular venous blood samples were collected via an indwelling catheter or by venipuncture. Plasma GH and IGF-I concentrations were measured by radioimmunoassay methods. In dry cows, the mean concentration of plasma GH after a single sc injection of hGRF analogs rose to 22.0-28.3 ng/ml at about 5 h from 1.4-1.7 ng/ml at 0 h (just before injection), and returned to the level before injection after 10-12 h. On the other hand, the plasma IGF-I began to increase after a lag of 4-6 h following a single injection of hGRF analogs, and reached maximum values of 71.1-89.4 ng/ml at 20 h from 43.7-46.4 ng/ml at 0 h. The IGF-I concentration at 24 h after a single injection of hGRF analogs was still higher than the value for the dry cows given saline. In lactating cows, the plasma concentration of GH at 2 h after daily sc injections of hGRF analogs during 14 consecutive days (an injection period) was higher than those for the lactating cows which received saline. Also, during the injection period, the concentration of IGF-I was higher in the lactating cows which received hGRF analog injections than in the cows which received saline injections. During the last 7 days of the injection period, the administration of hGRF analogs increased the mean milk yield by 11-19% in comparison with those for the saline injected cows. A positive correlation was observed between the mean plasma IGF-I concentration and the mean milk yield in the lactating cows treated with hGRF analogs throughout the injection and a postinjection (11 consecutive days after cessation of hGRF analog injection) periods. The results demonstrate that a single sc injection of hGRF analogs stimulates both GH release and the circulating level of IGF-I in dry cows, and that daily sc injections of hGRF analogs over 14 days enhance milk production, and plasma GH and IGF-I levels in lactating cows.     

Hyperparathyroidism associated with Cushing's syndrome due to an adrenal cortical adenoma

Two patients with the rare association of Cushing's syndrome and primary hyperparathyroidism are reported. Initially, both patients suffered from Cushing's syndrome due to adrenal cortical adenomas with typical features and laboratory findings. Five years after treatment of the Cushing's syndrome by removal of the tumor, asymptomatic mild hypercalcemia was incidentally noticed in both patients, which suggested the occurrence of primary hyperparathyroidism. An enlarged parathyroid gland was removed surgically in both cases and was histologically shown to be a parathyroid adenoma. The levels of serum calcium returned to normal after parathyroidectomy. Papillary adenocarcinoma of the thyroid in one patient and adenomatous goiter in the other were also incidentally detected at operation. These findings suggest that Cushing's syndrome resulting from an adrenal cortical adenoma may be another presentation of multiple endocrine neoplasia type I.     

Basigin, a new, broadly distributed member of the immunoglobulin superfamily, has strong homology with both the immunoglobulin V domain and the beta-chain of major histocompatibility complex class II antigen

Lotus tetragonolobus agglutinin (LTA) binds preferentially to early embryonic cells in the mouse. The affinity-purified antibody raised against LTA receptors from embryonal carcinoma cells were used to screen a lambda gt11 expression library of F9 embryonal carcinoma cells, resulting in detection of a cDNA clone specifying a new glycoprotein termed "basigin." The glycoprotein has been suggested to be a transmembrane one, and was found to be a new member of the immunoglobulin (Ig) superfamily. The molecular weight of basigin was largely in the range between 43,000 and 66,000, while that of the peptide portion with a putative signal sequence was inferred to be about 30,000. Significant levels of basigin mRNA were detected not only in embryonal carcinoma cells, but also in mouse embryos at 9-15 days of gestation and in various organs of the adult mouse. The Ig-like domain of basigin is unique, since it has strong homology to both the beta-chain of major histocompatibility class II antigen and the Ig V domain. The number of amino acids between the two conserved cysteine residues is intermediate between those of the Ig V and C domains. Therefore, basigin is an interesting protein in connection with the molecular evolution of the superfamily.     

A microcytofluorometric method for quantitative and qualitative evaluation of CFU-E and BFU-E colonies

Summary A new method has been developed for the precise identification of human bone marrow colony forming unit erythroid (CFU-E) and burst forming unit erythroid (BFU-E) colonies, and for determination of the hemoglobin contents using microcytofluorometry. The method relies on a photochemical reaction in which intracellular hemoglobin is converted into fluorescent porphyrin under violet light (=405 nm) in the presence of an SH-donor (mercaptoethylamine hydrochloride). The CFU-E and BFU-E colonies showed red fluorescence with two spectrum peaks at 600 and 650 nm when illuminated by violet light. These two peaks are consistent with those of porphyrin fluorescence. The porphyrin fluorescence was not inducible in colony forming unit granulocyte-macrophage (CFU-GM) colonies, while 20% of the CFU-GM colonies were false positive with respect to the conventional benzidine reaction. The photochemically inducible fluorescence began to appear in BFU-E colonies on the 4th day of culture, while the same colonies started to be positive for the benzidine reaction on the 9th day. Therefore, the photochemical reaction was more specific and sensitive than the benzidine reaction for the identification of CFU-E and BFU-E colonies. In addition, this method enabled us to measure the hemoglobin level in the cells forming the colonies because the intensity of the fluorescence was proportional to the amount of hemoglobin when the photochemical reaction was carried out for 50 min. As a result of qualitative and quantitative analysis of CFU-E colonies by this method, it was possible to detect the hemoglobin levels in the colonies from 1 of 4 cases of untreated acute nonlymphocytic leukemia and from 2 of 4 cases of myelodysplastic syndrome in which the hemoglobin levels were too low to be detected by the benzidine reaction. These cases, where the CFU-E colonies showed very low levels of hemoglobin, were associated with poor prognosis. Thus, our method is useful for identifying CFU-E colonies, determining their hemoglobin synthesis, and as a cue to predict the clinical course of the patients.     

Spin-trapping studies on the reactions of Cr(III) with hydrogen peroxide in the presence of biological reductants: is Cr(III) non-toxic?

Cr(III), which is thought to be relatively non-toxic, was reduced to Cr(II) ion by biological reductants such as L-cysteine and NADH and Cr(II) thus formed could easily react with hydrogen peroxide (H2O2) to yield very reactive active oxygen species, hydroxyl radical (.OH). The formation of hydroxyl radical was detected by water-soluble spin-traps, alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN) and 5,5-dimethyl-1-pyrroline N-oxide (DMPO). This result indicates that non-toxic Cr(III) compounds have the possibility of causing dangerous effects to living organism in the presence of biological reductants.