1,25-Dihydroxyvitamin D3 and the regulation of the differentiation and function of macrophages and granulocytes

1,25-Dihydroxyvitamin D3 (1,25(OH)2D3) exerts a differential inhibitory effect on the formation of granulocyte, granulocyte/macrophage, and macrophage colonies grown from mouse bone marrow precursor cells; 50% inhibition was attained at 1.1, 2.3, and 23 nM 1,25(OH)2D3, respectively. The inhibition of colony formation, as well as phagocyte proliferation in liquid cultures, requires the presence of 1,25(OH)2D3 in the early stages of culture (up to 72 h after culture initiation). 1,25(OH)2D3 induces a dose- and time-dependent augmentation of the phagocytic capability of mononuclear phagocytes (up to 100%) towards both heat-killed yeast cells and IgG-coated sheep red blood cells. The augmentation of the phagocytic capability of the mononuclear phagocytes depends critically on when 1,25(OH)2D3 is added. It is effective when added up to 72 h after culture initiation, while at later stages (greater than or equal to 96 h) the cells are no longer induced to express enhanced phagocytic capability. We suggest that these phenomena may be relevant to hemopoietic processes.     

Fecundability and husband's age

The effect of husband's age on the probability of conception is evaluated from World Fertility Survey data in five developing countries: the Ivory Coast, Ghana Kenya, the Sudan, and Syria. Proportional hazards models, which include wife's age, husband's age, marriage duration, union type, and post-partum exposure as covariates, are used to describe the monthly conception rate for second and higher-order birth intervals in which no contraception was used. With the exception of Syria, the resulting models indicate that the effects of male age are generally small in relation to the influences of marital duration and the age of the woman.     

Dynamic properties of intermediate filaments: disassembly and reassembly during mitosis in baby hamster kidney cells

A morphological analysis of the organizational changes in the type III intermediate filament (IF) system in dividing baby hamster kidney (BHK-21) cells was carried out by immunofluorescence and immunoelectron microscopy. The most dramatic change occurred during prometaphase, when the typical network of long 10-nm-diameter IF characteristic of interphase cells disassembled into aggregates containing short 4-6 nm filaments. During anaphase-telophase, arrays of short IF reappeared throughout the cytoplasm, and, in cytokinesis, the majority of IF were longer and concentrated in a juxtanuclear cap. These results demonstrate that the relatively stable IF cytoskeletal system of interphase cells is partitioned into daughter cells during mitosis by a process of disassembly and reassembly. This latter process occurs in a series of morphologically distinct steps at different stages of the mitotic process.     

Rioarribasaurus,a new name for a Late Triassic dinosaur from New Mexico (USA)

The Late-Triassic-dinosaur generic nameCoelophysis Cope 1889 (type species C.bauri [Cope 1887]) is a nomen dubium because the lectotype of C.bauri, AMNH 2722, is four sacral vertebrae and a pubic process of the ilium that are not diagnostic. Dinosaur specimens from the famous Whitaker (“Coelophysis”) quarry in the Rock Point Member of the Chinle Formation at Ghost Ranch, New Mexico thus lack a valid name. We create a new genus and species name,Rioarribasaurus colberti, for these specimens.     

Isolation of brush-border membranes from rat and rabbit colonocytes: Is alkaline phosphatase a marker enzyme?

Summary A method for the isolation of brush-border membranes of large intestinal epithelial cells was developed, which is based on the purification of intact brush-border caps by Percoll^® density-gradient centrifugation followed by separation of the vesiculated brush-border membranes on sucrose gradients. The procedure has two major advantages in comparison to known methods: 1) its first step does not depend on the determination of marker enzymes and 2) the method is applicable to rats as well as rabbits without major modifications. Due to the lack of an accepted marker for the colonic brush-border membrane the validity of the isolation procedure was tested by its application to the small intestine. Rat small intestinal brush-border membranes were enriched 21-fold when compared to the homogenate. The method was used to evaluate alkaline phosphatase as a marker enzyme for the colonic brush-border membrane. The results suggest that alkaline phosphatase is not exclusively localized in the brush-border membrane since this enzyme was also associated with membranes having different physical properties.     

Growth Kinetics, Cell Shape, and the Cytoskeleton of Primary Astrocyte Cultures

Abstract: We examined correlations among growth kinetics, cell shape, and cytoskeletal protein content in rat astrocytes grown in primary culture. Cell suspensions from brains of newborn rats were seeded at densities from 0.2 to 3 × 10⁵/cm². At initial densities above 1 × 10⁵ the population increased to reach confluency by 10–12 days, after which cell number remained stable for many weeks. At low initial densities, 0.2–0.4 × 10⁵/cm², cells did not increase in number. Final density increased with increasing plating densities. High-density cells had small perikarya and several long cytoplasmic processes; low-density cells appeared flat and polygonal. All cultures were almost entirely astrocytic, as judged by immunofluorescent staining with antiserum against glial fibrillary acidic protein (GFAP). Cytoskeletal proteins were analyzed by gel electrophoresis after extraction from cells with nonionic detergent. Relative amounts of the proteins differed, in that low-density cells contained large amounts of cytoskeletal actin relative to the intermediate filament (IF) proteins vimentin and GFAP, whereas high-density cells contained relatively less actin and more IF proteins. Such differences in cytoskeletal proteins between the high- and low-density cultures were mirrored in the relative rates of synthesis of the cytoskeletal proteins. In the low-density cells amino acid incorporation into cytoskeletal-associated actin was more active than that into the IFs, whereas in the high-density cells higher rates of IF protein synthesis were observed.     

A quantitative analysis of C3 binding to O-antigen capsule, lipopolysaccharide, and outer membrane protein of E. coli 0111B4

The binding of serum C3 to the O-antigen capsule (OAg Cap), lipopolysaccharide (LPS), and outer membrane proteins (OMP) of Escherichia coli 0111B4 was examined. Bacteria were intrinsically labeled with [3H] or [14C]galactose (*gal) in the OAg Cap and LPS moieties or with [14C]leucine (*leu) to label proteins. Organisms were then incubated in serum containing differentially labeled C3, the above fractions were separated, and the proportion of each binding to a column containing anti-C3 was measured. The OAg Cap fraction bound 72 to 82% of the C3, which bound to E. coli 0111B4 during incubation in absorbed 10% pooled normal human serum (10% PNHS) or absorbed 40% C8-deficient serum (C8D). This distribution did not change when the organism was presensitized with immune IgG before serum incubation. A total of 2.93% +/- 0.48 of OAg Cap and 0.52% +/- 0.16 of LPS *gal bound specifically to Sepharose-containing antibodies to C3 (A:C3-Seph) after incubation in 10% PNHS; these values increased to 10.1% +/- 4.5 and 1.8% +/- 0.3, respectively, when C3 deposition was increased fourfold by incubation in 40% C8D. When encapsulated E. coli 0111B4 was incubated in 10% PNHS containing biotinylated C3, specific attachment of OAg Cap *gal to avidin-Sepharose was demonstrated in 1% sodium dodecyl sulfate (SDS), and complete release of bound *gal but not C3 occurred with 1 M NH2OH. When a mutant of E. coli 0111B4 lacking OAg Cap was incubated in 40% C8D, the outer membrane (OM) bound 85% of C3. Five percent of OM *gal from the unencapsulated organism bound to A:C3-Seph in 0.05% SDS, indicating that the fraction of LPS molecules with bound C3 increased threefold in the absence of OAg Cap. OAg Cap does not contain protein, and no net specific binding of *leu from OAg Cap fractions to A:C3 was detectable; 2.4 to 3.6% of OM *leu bound to A:C3-Seph. Immunoprecipitation of 82.9% of OAg Cap *gal with antisera that were directed to E. coli 0111B4 was associated with co-precipitation of 69.5% of C3 in the capsular fraction. Therefore, the majority of C3 bound to E. coli 0111B4 was covalently attached to OAg Cap and LPS. As corroboration of experiments with whole bacteria, purified OAg Cap and purified LPS consumed C3 when incubated in serum in the fluid phase. These results are the first to evaluate the acceptor site for C3 deposition on a Gram-negative organism incubated in serum, and show that LPS, OAg Cap, and OMP are all major acceptor sites for C3 in nonimmune serum.