Cross reactive antigens of Acholeplasma laidlawii and L-form of Staphylococcus aureus]

We demonstrated that the membrane of Acholeplasma laidlawii PG8 and L-form of Staphylococcus aureus, both of which induce cellular immunity in BALB/c mice, were antigenically related each other. Foodpad responses of the mice immunized with a mixture of either antigen and Freund's complete adjuvant showed clearly a cross reaction when challenged with the other antigen. Cross responses to incorporate 3H-thymidine to the spleen lymphocytes of the mice immunized with either antigen occurred in the presence of the other antigen. Furthermore, the purified T cells, but not B cells, of the spleen were activated in the presence of antigen-presenting cells. These antigens existing in the membrane fractions of both microorganisms were purified by Razin's method. Finally, these membrane components of A. laidlawii and L-form of S. aureus were subjected to gel electrophoresis and transferring to nitrocellulose membrane and used to stimulate the spleen lymphocytes of the mice immunized with A. laidlawii or of non-immunized mice. The fractions representing molecular weights of approximately 45 kD, 25 kD, and 13 kD of both microorganisms consistently stimulated the lymphocytes of the immunized mice but not those of non-immunized mice.     

Chemical communication of emigration behavior of Drosophila melanogaster. II. Identification of chemical substances

Two chemical substances isolated from adult flies of Drosophila melanogaster differently affected the emigration activity of genetically different strains. These substances were identified as palmitic acid and oleic acid, respectively. Chemical and biological comparisons of the natural and authentic compounds showed them to be identical. The behavior response was dependent on the concentration of these fatty acids. The two chemical substances are excreted by adult flies, both male and female, but the emigration activity of one strain was affected by only palmitic acid and that of the other strain, by only oleic acid.     

Isolation and characterization of the adenylate cyclase structural gene of Neurospora crassa.

A single gene (nac) encoding an adenylate cyclase was cloned from the genomic DNA library of Neurospora crassa, using the DNA fragment encoding the catalytic domain of adenylate cyclase of Saccharomyces cerevisiae as a probe. The open reading frame of this gene (6900 base pairs) was interrupted three time by introns. The protein encoded consists of 2300 amino acids and has adenylate cyclase activity. N. crassa adenylate cyclase has a high degree of homology with the catalytic domains of yeast and bovine brain adenylate cyclases.     

Characterization of anti-Leb antibody purified from serum of immunized rabbits.

An anti-Le(b) antibody was produced in sera of rabbits by immunization with human saliva from blood group O Le(a-b+) secretor and purified by sequential use of silica beads immobilized with H type 1, Le(a) and Le(b). The purified antibody agglutinated only Le(a-b+) red cells irrespective of their ABO blood type. Hemagglutination reaction with the antibody of blood group O Le(a-b+) red cells was inhibited not only by saliva samples from blood group Le(a-b+) secretors and Synsorb beads immobilized with Le(b) hapten, but also weakly by Synsorb immobilized with Y and H type 2 haptens.     

Prevalence of Chlamydia trachomatis infections in Karachi, Pakistan.

An epidemiological study was carried out to determine the prevalence of Chlamydia infections in adult females by enzyme immunoassay and microscopic examination of Giemsa-stained smears. Endocervical swabs were collected from 126 females attending OB/GYN ward at Abbasi Shaheed Hospital, Karachi. 13.5% of 126 females tested were positive by enzyme immunoassay and only 5.6% were positive by the Giemsa-staining method. The infection rate among pregnant and nonpregnant women with urinogenital problems were 11.8% and 14.7%, respectively. The majority of females complained of excessive cervical discharge and pain in the lower abdomen. A high prevalence of infection in normal pregnant women (18.2%) indicates the asymptomatic nature of this infection.     

A comparison of three muscle pennation assumptions and their effect on isometric and isotonic force

Three different pennation angle assumptions are compared to experimental data from Huijing and Woittiez (Neth. J. Zool. 34, 21-32, 1984) that relate fibre length to angle of pennation changes. The assumptions tested are: (1) neglecting pennation; (2) assuming a fixed pennation; and (3) assuming a constant muscle volume and thickness resulting in pennation angle being dependent on fibre length. Each assumption is compared by transforming fibre force/length and force/velocity characteristics to muscle properties. In general, the fixed pennation assumption provides the worst estimate of muscle force output with a peak error of 0.31 Fo during isometric contractions at small muscle lengths. A better estimate of muscle force output was provided by neglecting pennation entirely. The assumption that the pennation angle changed with fibre length maintained an error of less than 0.05 Fo for most lengths and velocities tested and provided the best estimate of muscle force output.     

Birth spacing and infant mortality in Brazil

The effects of birth spacing on neonatal and post-neonatal mortality in Brazil were found to be very consistent with models based on data from other South American countries. The model for neonatal mortality simplified to three significant variables, whereas the model for post-neonatal mortality included four significant interactions.     

Sheep amniotic fluid has a protein factor which stimulates human fibroblast populated collagen lattice contraction.

Sutured incisional wounds made in fetal sheep and rabbits heal without scarring. Fetal sheep excisional wounds can close by contraction, but those in fetal rabbits do not. In vivo and in vitro evidence suggests that rabbit amniotic fluid inhibits wound contraction. The question arises: does sheep amniotic fluid promote wound contraction because their fetal wounds close by contraction? Sheep amniotic fluid (SAF) from 100 and 125 days gestation was tested in fibroblast populated collagen lattice (FPCL) system, an in vitro model of wound contraction. SAF stimulated FPCL contraction in a dose responsive manner. SAF from a 100 day fetus was more stimulating than a 125 day SAF. SAF enhanced FPCL contraction in the presence or absence of serum. SAF was fractionated by size, using column chromatography. It yielded a fraction with an estimated molecular weigh near 40,000 daltons, which stimulated FPCL contraction. The factor was inactivated by proteolytic digestion and heat denaturation. This protein fraction which stimulates FPCL contraction is not related to (1) actin-myosin filaments enhanced contraction by ATP-induced cell contraction, (2) promotion of fibroblast elongation on glass surface or in collagen, or (3) increased cell number by enhanced fibroblast duplication in a collagen matrix. A mechanism for SAF promotion of FPCL contraction was investigated but not identified.     

Cell polarity regulates the release of secretory component, the epithelial receptor for polymeric immunoglobulins, from the surface of HT-29 colon carcinoma cells.

The HT-29 human colon carcinoma cell line differentiates in glucose-free medium to an enterocytic phenotype. We previously isolated a series of HT-29 subclones selected for high levels of expression of secretory component (SC), the epithelial receptor for polymeric immunoglobulins. To develop a model system for studying effects of cell polarity on SC expression and release from the cell surface, the HT-29.74 subclone was induced to differentiate in glucose-free medium. Expression of SC was induced by glucose deprivation in both the parental HT-29 cell line and, to an even greater extent, in the HT-29.74 subclone. Prolonged glucose deprivation of HT-29.74 cells resulted in morphological changes consistent with enterocytic differentiation. Metabolic radiolabeling of SC in differentiated HT-29.74 cells indicated that proteolytic cleavage of membrane-bound to free SC occurred both on the cell surface and intracellularly, possibly in a vacuolar apical compartment or intrapeithelial lumen. To study effects of cell polarity on SC release, differentiated HT-29.74 cells were depolarized by culturing in low calcium medium. Within 2 hours after transfer of the cells into low calcium medium, a burst of SC release was observed concomitant with cell depolarization. Subsequently, release of SC declined significantly and remained low as long as cells were maintained in a depolarized state. The extent of cell depolarization could be controlled by varying the extracellular calcium concentration or by substituting the divalent cation Sr++, which partially prevents depolarization, for Ca++. In either case, the magnitude of the initial burst and subsequent decline in release of SC was proportional to the extent of cell depolarization. We conclude that cell polarity plays an important role in controlling the release of SC in intestinal epithelial cells, most likely by regulating the distribution of membrane-bound SC and SC protease, which are on the basolateral and apical cell surfaces, respectively, in differentiated cells.