A protein phosphotyrosine phosphatase distinct from alkaline phosphatase with activity against the insulin receptor.

Rat liver plasma membranes were found to have a relatively high ratio of acid to alkaline phosphatase activity when compared to rabbit liver and human placental membranes, respectively. The rat liver plasma membranes contained PPTl phosphatase activity against the soluble autophosphorylated insulin receptor beta-subunit. The PPT phosphatase activity of the membranes, using 32P-histone 2b as a substrate, was inhibited by 100 microM Zn+2, insensitive to 10 mM EDTA, and displayed maximal activity at neutral pH.

Functional multiplicity of atrial natriuretic peptide receptors on cultured rat Leydig tumor cells.

Native rat atrial natriuretic peptide (NANP) was shown to bind with high affinity and to increase intracellular levels of cGMP in cultured rat Leydig tumor cells. A linear analog of NANP which lacks the disulfide-linked bridge structure also bound with high affinity but did not increase levels of intracellular cGMP or antagonize the increase of this cyclic nucleotide by NANP. These data are consistent with the existence of two functional subpopulations of ANP receptors on cultured rat Leydig tumor cells; one which is capable of activating guanylate cyclase and one which is not linked to this enzyme.

Trematode transmission patterns.

The primitive transmission pattern in the Trematoda is a 1-host pattern in which an aspidocotylean matures in a mollusc. The progeny from the parent aspidocotylean typically disseminate from the mollusc to establish in others, but the possibility that some progeny remain in the same mollusc as did the parent and produce a sequential generation exists. It is this potential for sequential generations in the mollusc that may be the key to understanding the complex transmission and life cycle patterns in the Digenea.

Interleukin 1 beta is localized in the cytoplasmic ground substance but is largely absent from the Golgi apparatus and plasma membranes of stimulated human monocytes.

The subcellular location of IL-1 beta was determined using a postsectioning immunoelectron microscopic method on ultrathin frozen sections of human monocytes stimulated with LPS. This methodology permits access of antibody probes to all sectioned intracellular compartments, and their visualization at high resolution. Staining was performed with a rabbit antibody that specifically recognized amino acids 197-215 in the 33-kD IL-1 beta precursor molecule, followed by affinity-purified goat anti-rabbit IgG conjugated to 10 nm colloidal gold particles.

Development of a high capacity microassay for measurement of neutrophil adhesion.

A high capacity semiautomated assay for neutrophil adhesion was developed utilizing the 96 well microtiter plate format. Optimal adhesion occurred with about 150 microliters/well of neutrophils at 5 X 10(6) cells/ml in tissue culture plates that had been precoated with 5% serum. Optimal incubation times were 10 min for f-Met-Leu-Phe-treated cells and 20 min for A23187 or phorbol myristate acetate stimulation.

Rabbit apolipoprotein A-I mRNA and gene. Evidence that rabbit apolipoprotein A-I is synthesized in the intestine but not in the liver.

In order to study the tissue-specific expression of rabbit apolipoprotein (apo) A-I, a 923-base-pair clone, pRBA-502, complementary to rabbit apo A-I mRNA was identified from a rabbit intestinal cDNA library by hybrid-select translation and immunoprecipitation methods. Northern blot and dot-blot hybridization, utilizing 32P-labeled pRBA-502, revealed that the rabbit apo A-I gene is expressed in the intestine, not in the liver and that rabbit apo A-I mRNA is about 950 nucleotides in length. The entire nucleotide sequence of pRBA-502 has been determined and the complete amino acid sequence of the corresponding apo A-I has been deduced.

Difficidin and oxydifficidin: novel broad spectrum antibacterial antibiotics produced by Bacillus subtilis. III. Mode of action of difficidin.

The mode of action of difficidin (DIF) was investigated. Upon addition of DIF to log phase cultures of Escherichia coli, growth ceased immediately and small round cells accumulated after 30 minutes incubation. No cell lysis was observed.

High-performance liquid chromatography of phenylthiocarbamyl-amino acids. Application to carboxyl-terminal sequencing of proteins.

A carboxyl-terminus microsequencing method has been developed on the basis of carboxypeptidase A digestion and derivatization of released amino acids with phenylisocyanate followed by subsequent high-performance liquid chromatographic analysis of the resulting phenylthiocarbamyl amino acids. This technique has been used to confirm the carboxyl-terminal sequence of bovine brain-derived acidic fibroblast growth factor. The method is of general application for the microsequencing of the carboxyl-termini of proteins.

Assessment of gastric bleeding in rats: effects of cyclooxygenase inhibitors and 16,16-dimethyl prostaglandin E2 on gastric bleeding.

Gastric bleeding caused by cyclooxygenase inhibitors has been assessed by a novel method. Rats are adapted to a strict light-dark cycle with limited access to food to reduce the stress associated with starvation. Such animals are then labeled with 51Cr-red blood cells from donor animals and dosed with the compound under evaluation.

The actions of atrial natriuretic factor on the vascular wall.

The actions of atrial natriuretic factor (ANF) on the vascular wall are diverse and show a profound regional heterogeneity. ANF is a potent relaxant of aortic smooth muscle, a response which is associated with activation of particulate guanylate cyclase and elevation in tissue levels of cyclic GMP. However, many large and small muscular arteries and most veins are unresponsive to the peptide.

A comparison of bovine growth hormone expression directed by bGH genomic or intronless DNA in transiently transfected eukaryotic cells.

Two recombinant DNA plasmids were constructed with identical transcriptional and translational regulatory elements controlling expression of the bovine growth hormone (bGH) gene or the bGH gene lacking introns. Transient expression of these plasmids in cultured eukaryotic cells, monitored by assaying secretion of bGH into the culture medium, was employed to examine the relative importance of introns in the expression of this gene. The bGH gene lacking introns is expressed more efficiently than the bGH gene in avian and mammalian cells.

Ivermectin: an update.

Ivermecan was introduced as an antiparasitic agent in 1981. It is now registered for animal-health use in 35 countries and is being evaluated for possible use in man. This review summarises its antiparasitic efficacy and apparent mode of action.

DNA single-strand breaks, double-strand breaks, and crosslinks in rat testicular germ cells: measurements of their formation and repair by alkaline and neutral filter elution.

This work describes a neutral and alkaline elution method for measuring DNA single-strand breaks (SSBs), DNA double-strand breaks (DSBs), and DNA-DNA crosslinks in rat testicular germ cells after treatments in vivo or in vitro with both chemical mutagens and gamma-irradiation. The methods depend upon the isolation of testicular germ cells by collagenase and trypsin digestion, followed by filtration and centrifugation. 137Cs irradiation induced both DNA SSBs and DSBs in germ cells held on ice in vitro.

GELRITE as an Agar Substitute in Bacteriological Media.

GELRITE gellan gum (formerly known as PS-60 and S-60) is a new naturally derived, highly purified polysaccharide which displays several interesting properties, including selfgelling. The suitability of GELRITE as an agar substitute was tested by evaluating the performance of several media selected from among those most commonly used in the isolation, identification, and enumeration of microorganisms in clinical laboratories. Fifty different bacterial species previously implicated in human infections served as test strains.

Cleavage properties of site-specific restriction endonucleases.

Among the various restriction sites present on a DNA molecule, the restriction endonucleases prefer specific ones. This site preference may be an inherent property of the restriction endonucleases or may reflect the complexities inherent in the DNA molecule. The site preference of restriction endonucleases can be amplified by the use of intercalators that bind to DNA.

A latex test for canine rheumatoid factor.

Canine rheumatoid factor (RF) has been reported in several canine diseases, particularly in arthritis. Although RF can be assayed using IgG sensitized erythrocytes, the test has a number of disadvantages. As an alternative, latex sensitized with canine IgG was investigated as an assay of canine RF.

Cefoxitin and cephamycins: microbiological studies.

The cephamycins are a family of beta-lactam antibiotics that are produced by actinomycetes and are structurally similar to the cephalosporins. They are characterized by the presence of a 7-alpha-methoxyl group, which confers unusually high resistance to beta-lactamases. Cefoxitin, the first semisynthetic cephamycin, is resistant to almost all beta-lactamases.

Virulence of R-Factor-Bearing Salmonella typhimurium.

Antibiotic-resistant recombinants obtained from mating antibiotic-resistant Escherichia coli with virulent, antibiotic-sensitive Salmonella typhimurium are generally avirulent. After 32 consecutive transfers, two of four avirulent recombinants regained their virulence without loss of episome-mediated resistance.

Double-stranded polynucleotides as interferon inducers.

A discussion of factors considered influential in making a polynucleotide an efficient inducer of interferon was presented. These factors were double-strandedness of the polynucleotides, the sugar moiety of the polynucleotides, thermal stability, resistance to enzymatic degradation, and molecular size of the polynucloetides. Recent developments concerning interferon induction during virus infection were also discussed.