Modal damping for monitoring bone integrity and osteoporosis

We applied a noninvasive method to assess bone structural integrity. The method is based on the measurement of the dynamic characteristics of the bone (quality factor and modal damping factor) by applying vibration excitation in the range of acoustic frequencies, in the form of an acoustic sweep signal. Excised sheep femora were tested to detect changes in modal damping, density (kg/m3), bone mineral density (kg/m2) and bone mineral (hydroxyapatite) percentage. The changes were recorded after each time of chemical treatment of the bones performed to gradually cause mineral removal, thus simulating osteoporosis. It was shown that the change in quality factor and damping was in all cases on average equal or greater to the change in all other measured characteristics, thus strengthening the potential of the proposed method to become a valuable assessment tool for monitoring bone integrity and osteoporosis.     

CC chemokine receptor 9 expression defines a subset of peripheral blood lymphocytes with mucosal T cell phenotype and Th1 or T-regulatory 1 cytokine profile

The chemokine receptor CCR9 is expressed on most small intestinal lamina propria and intraepithelial lymphocytes and on a small subset of peripheral blood lymphocytes. CCR9-expressing lymphocytes may play an important role in small bowel immunity and inflammation. We studied the phenotype and functional characteristics of CCR9(+) lymphocytes in blood from normal donors. A subset of CCR9(+) T cells have a phenotype of activated cells and constitutively express the costimulatory molecules CD40L and OX-40. In contrast to CCR9(-), CCR9(+)CD4(+) peripheral blood T cells proliferate to anti-CD3 or anti-CD2 stimulation and produce high levels of IFN-gamma and IL-10. IL-10-producing cells were exclusively detected within the CCR9(+) subset of CD4(+) T cells by intracellular staining and were distinct from IL-2- and IFN-gamma-producing cells. Moreover, memory CCR9(+)CD4(+) lymphocytes respond to CD2 stimulation with proliferation and IFN-gamma/IL-10 production, whereas memory CCR9(-)CD4(+) cells were unresponsive. In addition, memory CCR9(+)CD4(+) T cells support Ig production by cocultured CD19(+) B cells in the absence of prior T cell activation or addition of exogenous cytokines. Our data show that the memory subset of circulating CCR9(+)CD4(+) T cells has characteristics of mucosal T lymphocytes and contains cells with either Th1 or T-regulatory 1 cytokine profiles. Studies on the cytokine profile and Ag specificity of this cell subset could provide important insight into small intestinal immune-mediated diseases and oral tolerance in humans.     

Binding of zona binding inhibitory factor-1 (ZIF-1) from human follicular fluid on spermatozoa

Previous studies showed that zona binding inhibitory factor-1 (ZIF-1) was the glycoprotein mainly responsible for the spermatozoa zona binding inhibitory activity of human follicular fluid. ZIF-1 has a number of properties similar to glycodelin-A. A binding kinetics experiment in the present study demonstrated the presence of two binding sites of ZIF-1 on human spermatozoa. These binding sites were saturable, reversible, and bound to (125)I-ZIF-1 in a time-, concentration-, and temperature-dependent manner. Glycodelin-A shared one common binding site with ZIF-1 on spermatozoa, and it could displace only 70% of the (125)I-ZIF-1 bound on human spermatozoa. ZIF-1 and glycodelin-A formed complexes with the soluble extract of human spermatozoa. Coincubation of solubilized zona pellucida proteins reduced the binding of ZIF-1 to two complexes of the extract, suggesting that the ZIF-1 binding sites and zona pellucida protein receptors on human spermatozoa were closely related. ZIF-1, but not glycodelin-A, significantly suppressed progesterone-induced acrosome reaction of human spermatozoa. The carbohydrate moieties derived from ZIF-1 reduced the binding of native ZIF-1 on human spermatozoa as well as the zona binding inhibitory activity of the glycoprotein, although the intensity of the effects are lower when compared with the native protein. These effects are not due to the action of the molecules on the motility, viability, and acrosomal status of the treated spermatozoa. Deglycosylated ZIF-1 had no inhibitory effect on both ZIF-1 binding and zona binding capacity of spermatozoa. We concluded that the carbohydrate part of ZIF-1 was critical for the functioning of the glycoprotein.     

The spatial organization of centromeric heterochromatin during normal human lymphopoiesis: evidence for ontogenically determined spatial patterns

It is believed that pericentromeric heterochromatin may play a major role in the epigenetic regulation of gene expression. We have previously shown that centromeres in human peripheral blood cells aggregate into distinct "myeloid" and "lymphoid" spatial patterns, suggesting that the three-dimensional organization of centromeric heterochromatin in interphase may be ontogenically determined during hematopoietic differentiation. To investigate this possibility, the spatial patterns of association of different centromeres were analyzed in hematopoietic progenitors and compared with those in early-B and early-T cells, mature B and T lymphocytes, and, additionally, mature granulocytes and monocytes. We show that those patterns change during lymphoid differentiation, with major spatial arrangements taking place at different stages during T and B cell differentiation. Heritable patterns of centromere association are observed, which can occur either at the level of the common lymphoid progenitor, or in early-T or early-B committed cells. A correlation of the observed patterns of centromere association with the gene content of the respective chromosomes further suggests that the variation in the composition of these heterochromatic structures may contribute to the dynamic relocation of genes in different nuclear compartments during cell differentiation, which might have functional implications for cell-stage-specific gene expression.     

Low-temperature sensors in bacteria

Bacteria are ubiquitous colonizers of various environments and host organisms, and they are therefore often subjected to drastic temperature alterations. Temperature alterations set demands on these colonizers, in that the bacteria need to readjust their biochemical constitution and physiology in order to survive and resume growth at the new temperature. Furthermore, temperature alteration is also a main factor determining the expression or repression of bacterial virulence functions. To cope with temperature variation, bacteria have devices for sensing temperature alterations and a means of translating this sensory event into a pragmatic gene response. While such regulatory cascades may ultimately be complicated, it appears that they contain primary sensor machinery at the top of the cascade. The functional core of such machinery is usually that of a temperature-induced conformational or physico-chemical change in the central constituents of the cell. In a sense, a bacterium can use structural alterations in its biomolecules as the primary thermometers or thermostats.     

Malnutrition and its association with intestinal parasitism among children from a village in the Colombian Amazonian region

Intestinal parasites and malnutrition cause high morbidity among children in developing countries. A study to establish the associations between intestinal parasitism and undernourishment was undertaken in a village in the Colombian Amazon region. Two hundred thirty seven children each provided four stool samples for parasitic analysis. Anthropometric indices were calculated based on height and weight (HAZ), weight and age (WAZ) and height and weight (WHZ) using the international growth standards recommended by the World Health Organization. Of the 237 children, 86.1% were carrying parasites, 54% had 2 or more parasites, 30% were stunted, 10% were underweight, and 2.5% were wasting. HAZ and WAZ indices were inversely related to age and number of parasites. Socioeconomic status was positively correlated with the number of parasites and inversely related to the HAZ index (p < 0.05). In conclusion, frequencies of undernourishment and intestinal parasites among the sample population were higher than the national average for Colombia. As previous studies have indicated, age, intestinal parasitism and socio-economic level are variables significantly related to nutritional state.     

Pharmacological characterization of cloned chicken neuropeptide Y receptors Y1 and Y5

The neuropeptide Y (NPY) receptor subtypes Y1 and Y5 are involved in the regulation of feeding and several other physiological functions in mammals. To increase our understanding of the origin and mechanisms of the complex NPY system, we report here the cloning and pharmacological characterization of receptors Y1 and Y5 in the first non-mammal, chicken (Gallus gallus). The receptors display 80-83% and 64-72% amino acid sequence identity, respectively, with their mammalian orthologues. The three endogenous ligands NPY, peptide YY (PYY) and pancreatic polypeptide (PP) have similar affinities as in mammals, i.e. NPY and PYY have subnanomolar affinity for both receptors whereas chicken PP bound with nanomolar affinity to Y5 but not to Y1. A notable difference to mammalian receptor subtypes is that the Y1 antagonist SR120819A does not bind chicken Y1, whereas BIBP3226 does. The Y5 antagonist CGP71863A binds to the chicken Y5 receptor. Anatomically, both Y1 and Y5 have high mRNA expression levels in the infundibular nucleus which is the homologous structure of the hypothalamic arcuate nucleus in mammals. These results suggest that some of the selective Y1 and Y5 antagonists developed in mammals can be used to study appetite regulation in chicken.     

Tobacco-smoke exposure indicators and urinary mutagenicity

The protective effect of calcium given orally by gavage with two doses (40 and 80mg/kg body weight) was evaluated against clastogenecity induced by lead acetate with two concentrations (200 and 400mg/kg diet) on bone marrow and spermatocyte cells of mice in vivo. The parameter screened was percentage of chromosomal aberrations with and without gaps and sperm abnormalities. Statistical analyses indicated the protection efficacy of calcium with the high dose rather than the other in both types of mouse cells.The observation from the laboratory tests, dealing that lead acetate can be considered as an environmental genotoxic material. We recommended that it must be administered of calcium (as calcium chloride) as a protective agent to reduce the genotoxic effect of lead in the somatic and germ cells.     

The selective regulation of alpha Vbeta 1 integrin expression is based on the hierarchical formation of alpha V-containing heterodimers

The integrin beta1 subunit can form a heterodimer with 12 different alpha subunits. According to the present model, the expression level of any alphabeta complex is regulated by the availability of the specific alpha subunit, whereas beta1 subunit is constantly present in a large excess. The expression of several heterodimers containing the alphaV subunit seems to be regulated by an identical mechanism. The fact that many cells express alphaVbeta1 heterodimer, and that this fibronectin/vitronectin receptor may be selectively regulated, compromises the present model of the regulation of beta1 and alphaV integrins. We have tried to solve this problem by assuming that distinct alphabeta heterodimers are formed with different tendency. To test the hypothesis, we analyzed WM-266-4 melanoma cells transfected with a cDNA construct coding for an intracellular single-chain anti-alphaV integrin antibody. We could see 70-80% reduction in the cell surface expression of alphaV subunit. However, the only one of the alphaV integrins reduced on the cell surface was alphaVbeta1. This suggests that the cell surface expression level of alphaVbeta1 is dependent on the number of alphaV subunits available after the formation of other alphaV-containing heterodimers. Thus, there seems to be a hierarchy in the complex formation between alphaV and its different beta-partners. These observations explain how alphaVbeta1 can be specifically regulated without concomitant changes in the expression of other alphaV or beta1 integrins.