Structure and evolution of the heavy chain from rat immunoglobulin E.

The nucleotide sequence of the rat epsilon-chain mRNA has been determined by sequencing cloned cDNA copies of the mRNA. The established sequence covers the coding region, the 3'-non coding region and most of the 5' non-coding region. A comparison with the nucleotide sequence of the human epsilon-chain constant region reveals that C3 and C4 are the most highly conserved domains. The rat epsilon-chain contains a C-terminal decapeptide which is not present in the human counterpart.     

Determination and Health-Risk Evaluation of Nitroxynil Residues in the Edible Tissue of Cattle

A specific Polarographic method with a sensitivity of ≥ 2 jig/kg (ppb) has been used to determine the plasma and tissue concentrations of nitroxynil (NTX), which is used against Parafilaria bovicola in cattle. After treatment with the therapeutic dose on NTX (2 × 20 mg/kg b.w., s,c), there was an initial rapid decrease in the plasma concentration followed by a slower elimination phase. The plasma levels of NTX were 8 mg/kg (ppm) and 3 mg/kg after 6 weeks and 2 months, respectively. The muscle and other edible tissue from treated cattle contained 0.1–0.3 mg/kg NTX after 2 months, and jxg/kg amounts were still detectable 3 months after the injection. Based on available pharmacological and toxicological data, a 3-months withdrawal time for NTX in cattle is proposed.     

Cosmid cloning and transposon mutagenesis in Salmonella typhimurium using phage lambda vehicles

Summary We have constructed a strain of Salmonella typhimurium which contains the malB region from Escherichia coli and carries the bacteriophage receptor protein in its outer membrane. Phage adsorbs to this strain but cannot grow, thus providing a very useful system for transposon mutagenesis of S. typhimurium using vehicles carrying transposons. This system can also be used for cosmid cloning.     

Leukotriene C5: a slow reacting substance derived from eicosapentaenoic acid

Mouse mastocytoma cells incubated with ionophore A23187 and eicosapentaenoic acid (n-3) produced a slow reacting substance with different properties compared with leukotriene C4 (previously designated leukotriene C). This product was characterized by spectroscopy and enzymatic and chemical degradations to be 5-hydroxy-6-S-glutathionyl-7,9,11,14,17-eicosapentaenoic acid (leukotriene C5). Leukotriene C5 has similar biological activity on the isolated guinea pig ileum but is less potent than is leukotriene C4.     

Perchlorate binding to cytochrome c: a magnetic and optical study

1. The effects of perchlorate on cytochrome c have been investigated by 1H and 35Cl NMR, electron paramagnetic resonance and optical spectroscopy. 2. The pK values for the formation and disappearance of the major alkaline conformation were found to be displaced from 9.3 to 8.3 and from 10.4 to 10.9, respectively. The displacement was dependent on the ClO4(-) concentration below 0.1 M. 3. Competition experiments between perchlorate and chloride show that ClO4(-) binds both to the neutral and alkaline forms but with a higher affinity for the latter. The appearance of a new binding site in the alkaline form accounts for the markedly enhanced relaxation rate of 35ClO4(-) in this pH range. Complex formation between cyanide and the alkaline species results in the loss of this binding site, which probably is located close to or within the heme crevice. 4. The neutral form of ferricytochrome c also binds perchlorate strongly as evidence by the unique appearance of a high-spin signal dependent on pH and perchlorate concentration. This signal disappears with the same pK value as the neutral form. The effects of perchlorate on cytochrome c are due to specific binding of this ion.     

Genetic control of effector cell characteristics: con A-induced suppressor cells carry H-2 I region encoded determinants.

Activation of splenic lymphocytes with Con A leads to the formation of suppressor cells capable of interfering with the activity of several polyclonal B-cell-activating substances. Thus, these suppressor cells, or their products, most probably act directly on B cells. Suppressor cells could be recovered from the effluent cell population of nylon wool columns, and they were absent from the spleens of athymic nude mice. Furthermore, they were absent from the thymus of normal as well as cortison-treated mice. Cortisone treatment did not abolish the formation of Con A-induced suppressor cells in the spleen. Treatment of activated suppressor cells with antisera specific for distinct products of the H-2 I region revealed that they carried I-J cell surface antigens. We conclude that the suppressor cells in our test system, which unlike other Con A-induced suppressor cell populations have a direct effect on B cells, had antigenic characteristics similar to those previously described for I-J carrying suppressor cells.     

Adenosine triphosphate hydrolysis in rat dental tissues. A histochemical study to differentiate the enzymes involved.

The purpose of this study was to try to differentiate histochemically between the various enzymes which may catalyze the hydrolysis of ATP in developing rat dental tissues. Freeze cut and freeze dried sections of molar and incisor teeth were incubated in lead capture-based media at pH 5.0, 7.2 or 9.4 with one of the following substrates: beta-glycerophosphate, AMP, ADP, ATP, AMP-PNP and tetrasodium pyrophosphate. To establish the enzymatic nature of the hydrolysis parallel sections were incubated after prior fixation in either formaldehyde or glutaraldehyde. By comparing the enzymatic stainings obtained with the various substrates and at the different pH:s, it was concluded that ATP can be visibly hydrolyzed in rat dental tissues by alkaline phosphatase (stratum intermedium, apical part of maturation ameloblasts, basal part of all ameloblasts, odontoblasts and subodontoblastic layer), specific ATPase (apical and basal parts of secretory ameloblasts) and ATP pyrophosphatase and/or adenylate cyclase (stratum intermedium, odontoblasts). Acid phosphatase, specific ADPase, 5'-nucleotidase, inorganic pyrophosphatase, 3':5'-cyclic-AMP-phosphodiesterase and adenylate kinase on the other hand, seem not to be engaged in the ATP hydrolysis to such a degree as to complicate the interpretation of the histochemical staining. The alkaline phosphatase part of the ATP hydrolysis appeared to be rather insensitive to aldehyde fixation, while the hydrolysis effected by specific ATPase and ATP pyrophosphatase and/or adenylate cyclase was extinguished after fixation with formaldehyde for 4 h or glutaraldehyde for 10 min.     

Prostaglandins,indomethacin and dysmenorrhea

Uterine contractility was recorded during the period of menstruation in six dysmenorrheic women. A variable high tonus was observed in each case. Uterine recordings were repeated during the subsequent menstruation following pre-treatment with indomethacin at an oral dose of 75 mg or 200 mg per day beginning one day before the expected onset of menstruation. A lower uterine tonus was found in all indomethacin-treated cycles. Complete alleviation of spasmodic pain was obtained in the six subjects. The endogenous concentration of 15-keto-13,14-dihydro PGF_2α was determined by the gas chromatography-mass spectrometry method and observed to be relatively high in women with dysmenorrhea.     

Tumor-associated blocking factors: isolation from sera of tumor-bearing mice.

An isolation and partial purifications of tumor-associated blocking factors from the sera of tumor-bearing mice is described. Columns for affinity chromatography were prepared by coupling syngeneic tumor-immune antibodies to Sepharose 4B. Passage of serum through such immunoadsorbent columns removed all blocking activity from tumor-bearers' sera; subsequent elution of the absorbent with 3 M NaSCN recovered the activity. The blocking material was further purified on Sephadex G-200. The data provide evidence for the presence of antigen in tumor-associated blocking factors and are compatible with the hypothesis that blocking factors often consist of antigen and antibodies in the form of immune complexes.