Regularity in irregular echinoids

Using the mathematical concept of eutactic star, we prove that it is possible to define a morphospace for irregular echinoids by using a single parameter. In particular, we have found an extraordinary geometric property in the flower-like patterns of the five ambulacral petals of these animals. This property is fulfilled with great accuracy for a large collection of fossil specimens and provides new insights in the study of the viable skeletal designs of extinct and/or living organisms.

Analysis of BRCA1 and BRCA2 in breast and breast/ovarian cancer families shows population substructure in the Iberian peninsula

An estimated 5-10% of all breast and ovarian cancers are due to an inherited predisposition, representing a rather large number of patients. In Spain 1/13-1/14 women will be diagnosed with breast cancer during their lifetime. Two major breast cancer genes, BRCA1 and BRCA2, have been identified. To date, several hundred pathogenic mutations in these two genes have been published or reported to the Breast Cancer Information Core, BIC database (http://www.nhgri.nih.gov/Intramural_research_Lab transfer/Bic/index.html). In the present study, 30 Spanish breast and breast/ovarian cancer families (29 from Galicia, NW Spain, and 1 from Catalonia, NE Spain) were screened for mutations in the BRCA1 and BRCA2 genes. The analysis of these genes was carried out by SSCP for shorter exons and direct sequencing in the case of longer ones. Mutations were found in 8 of the 30 families studied (26.66%). It is important to note that all mutations were detected within the BRCA1 gene: 330 A>G, 910_913delGTTC, 2121 C>T, 3958_3962delCTCAGinsAGGC, and 5530 T>A. The BRCA1 330 A>G mutation was found in four unrelated families and accounted for 50% of all identified mutations.

Chromosome-12 mapping of late-onset Alzheimer disease among Caribbean Hispanics

Linkage to chromosome 12p for familial Alzheimer disease (AD) has been inconsistent. Using 35 markers near the centromere of chromosome 12, we investigated 79 Caribbean Hispanic families with AD. Two-point linkage analysis using affected sib pairs yielded LOD scores of 3.15 at D12S1623 and 1.43 at D12S1042. The LOD score at D12S1623 decreased to 1.62 in families with late-onset (age >65 years) AD (LOAD), but the LOD score at D12S1042 was unchanged. Among families negative for the apolipoprotein E (APOE-epsilon 4) allele, the LOD score for D12S1623 was lower (1.01), whereas that for D12S1042 increased to 1.73. Among families positive for the APOE-epsilon 4 allele, none of the LOD scores reached 1. Multipoint affected-relative-pair analysis showed peaks at D12S1623 (nonparametric linkage [NPL] score 1.52; P=.028) and near D12S1042, at D12S1057 (NPL score 1.57; P=.027). NPL scores for both D12S1623 and D12S1057 increased in families affected with LOAD, but, in APOE-epsilon 4-negative families, only scores for the region flanking D12S1623 remained elevated (NPL score 1.74; P=.013). This study of Caribbean Hispanics with familial AD extends and provides modest evidence of linkage to loci on chromosome 12p. Linkage varied by age at onset of AD and by the presence or absence of the APOE-epsilon 4 allele.

Prolonged exposure to YC-1 induces apoptosis in adrenomedullary endothelial and chromaffin cells through a cGMP-independent mechanism

YC-1, a benzyl indazole derivative, is an NO-independent direct activator of soluble guanylyl cyclase (sGC), which presents a synergistic action with NO in stimulating cGMP synthesis. These properties have served to suggest YC-1 as an attractive therapeutic agent by permitting the reduction of nitrovasodilator dosage and regulating endogenous cGMP metabolism. Here we studied the effect of prolonged exposure of adrenomedullary endothelial and chromaffin cells to YC-1. We found that YC-1 increased cGMP in the two types of cells and this action was blocked by the sGC inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ). Cells underwent apoptotic death in association with increased caspase-3-like activity, DNA fragmentation, cytoskeletal disorganization and changes in membrane permeability after prolonged incubation with YC-1. Caspase-3-like protease activity and DNA fragments in the cytoplasm were increased in a dose-dependent manner by 16 h YC-1 treatment. The specific and cell permeable caspase-3-like protease inhibitor DEVD-CHO effectively inhibited YC-1-mediated caspase-3-like activation and DNA fragmentation. Moreover, YC-1 also induced cell shape changes accompanied by actin filament disorganization and alterations in membrane permeability. Cells incubated for 24h with YC-1 showed damaged membranes by binding to nucleic acid of a dye excluded by the intact plasma membrane of live cells. YC-1 also induced a decrease in the intracellular non-specific esterase activity, another indication of cell toxicity. Apoptotic phenomena were not prevented by the presence of ODQ although it effectively inhibited the YC-1-elicited cGMP increases. These findings indicate that YC-1 induces apoptosis by activating caspase-3-like protease through a mechanism independent of sGC activation.

A founder mutation in presenilin 1 causing early-onset Alzheimer disease in unrelated Caribbean Hispanic families

CONTEXT

Genetic determinants of Alzheimer disease (AD) have not been comprehensively examined in Caribbean Hispanics, a population in the United States in whom the frequency of AD is higher compared with non-Hispanic whites.

OBJECTIVE

To identify variant alleles in genes related to familial early-onset AD among Caribbean Hispanics.

DESIGN AND SETTING

Family-based case series conducted in 1998-2001 at an AD research center in New York, NY, and clinics in the Dominican Republic.

PATIENTS

Among 206 Caribbean Hispanic families with 2 or more living members with AD who were identified, 19 (9.2%) had at least 1 individual with onset of AD before the age of 55 years.

MAIN OUTCOME MEASURE

The entire coding region of the presenilin 1 gene and exons 16 and 17 of the amyloid precursor protein gene were sequenced in probands from the 19 families and their living relatives.

RESULTS

A G-to-C nucleotide change resulting in a glycine-alanine amino acid substitution at codon 206 (Gly206Ala) in exon 7 of presenilin 1 was observed in 23 individuals from 8 (42%) of the 19 families. A Caribbean Hispanic individual with the Gly206Ala mutation and early-onset familial disease was also found by sequencing the corresponding genes of 319 unrelated individuals in New York City. The Gly206Ala mutation was not found in public genetic databases but was reported in 5 individuals from 4 Hispanic families with AD referred for genetic testing. None of the members of these families were related to one another, yet all carriers of the Gly206Ala mutation tested shared a variant allele at 2 nearby microsatellite polymorphisms, indicating a common ancestor. No mutations were found in the amyloid precursor protein gene.

CONCLUSIONS

The Gly206Ala mutation was found in 8 of 19 unrelated Caribbean Hispanic families with early-onset familial AD. This genetic change may be a prevalent cause of early-onset familial AD in the Caribbean Hispanic population.

Control of retinal ganglion cell axon growth: a new role for Sonic hedgehog

Retinal ganglion cell (RGC) axons grow towards the diencephalic ventral midline during embryogenesis guided by cues whose nature is largely unknown. We provide in vitro and in vivo evidence for a novel role of Sonic hedgehog (SHH) as a negative regulator of growth cone movement. SHH suppresses both the number and the length of neurites emerging from the chick retina but not from neural tube or dorsal root ganglia explants, without interfering with their rate of proliferation and differentiation. Similarly, retroviral-mediated ectopic expression of Shh along the chick visual pathway greatly interferes the growth of RGC axons. Upon SHH addition to grown neurites, the intracellular level of cAMP decreases, suggesting that the dampening of growth cone extension mediated by SHH may involve interaction with its receptor Patched which is expressed by RGC. Based on these findings, we propose that Shh expression at the chiasm border defines a constrained pathway within the ventral midline which serves to guide the progression of RGC axons.

ADP stimulates the respiratory burst without activation of ERK and AKT in rat alveolar macrophages

Alveolar macrophages (AM) are the first line of defense against infection in the lungs. We previously showed that the production of superoxide and hydrogen peroxide, i.e., the respiratory burst, is stimulated by adenine nucleotides (ADP >> ATP) in rat AM through signaling pathways involving calcium and protein kinase C. Here, we further show that ADP induces a rapid increase in the tyrosine phosphorylation of several proteins that was reduced by the tyrosine kinase inhibitor genistein, which also inhibited the respiratory burst. Interestingly, ADP did not trigger the activation of the mitogen-activated protein kinases ERK1 and ERK2, or that of protein kinase B/AKT, a downstream target of the phosphatidylinositol 3-kinase (PI3K) pathway. This is in contrast to another stimulus of the respiratory burst, zymosan-activated serum (ZAS), which activates both the ERK and PI3K pathways. Thus, this study demonstrates that the receptor for ADP in rat AM is not coupled to the ERK and AKT pathways and, that neither the ERK pathway nor AKT is essential to induce the activation of the NAPDH oxidase by ADP in rat AM while tyrosine kinases appeared to be required. The rate and amount of hydrogen peroxide released by the ADP-stimulated respiratory burst was similar to that produced by ZAS stimulation. The absence of ERK activation after ADP stimulation therefore suggests that hydrogen peroxide is not sufficient to activate the ERK pathway in rat AM. Nonetheless, as hydrogen peroxide was necessary for ERK activation by ZAS, this indicates that, in contrast to ADP, ZAS stimulates a pathway that is targeted by hydrogen peroxide and leads to ERK activation.

[Quantification of T CD4+ lymphocytes and viral RNA in patients with HIV/AIDS]

Quantification of CD4+ T lymphocytes and viral RNA in patients with HIV/AIDS. Levels of progression markers (viral load and CD4+ T lymphocytes) in 410 patients with HIV/AIDS that were in different clinical stages of the disease and under different therapeutic schemes were quantified. The objective was to determine the correlation between values of progression markers and clinical stage of the patients. Commercial methodologies for the quantification of lymphocytes, subpopulations and circulating viral RNA were used. Results indicate that there was a correlation between low CD4+ values and high viral load in patients with antiretroviral treatment but not in patients without treatment. Furthermore, analysis of 1,208 samples processed during 1999 showed that 46% of the patients had less than 200 CD4+ T lymphocytes/mL blood and more than 500 copies of circulating viral RNA. Implications of these results in public health in Mexico are discussed.

Electrophysiological and hemolytic activity elicited by the venom of the jellyfish Cassiopea xamachana

In this study, we determined hemolysis activity in human and sheep erythrocytes, and characterized the electrical responses in Xenopus oocyte membrane elicited by the venom of the jellyfish Cassiopea xamachana (Cx). The Cx venom produced hemolysis in both species, being more potent on human red cells. The electrophysiological study showed that the Cx venom elicited three different responses in the oocytes. One current was generated in all the oocytes tested and corresponded with a slow inward current (I(Cx)) associated with an increase in membrane conductance. I(Cx) was concentration-dependent and had a reversal potential of -10.3+/-0.4 mV. Ionic substitution studies indicated that the conductive pathway was mainly permeable to cations and non-selective. The oocyte membrane resistance was completely recovered after washout of the venom, this suggested that the effect was due to generation of a specific membrane conductance as opposed to a possible non-specific membrane breakdown. A comparative study with three distinct native cationic channels present in the oocyte membrane [i.e. (1) hemi-gap-junction channels, (2) mechanosensitive channels, and (3) the ouabain-sensitive channel activated by palytoxin], showed that I(Cx) might correspond to opening of mechanosensitive channels or to activation of an unknown cationic channel located in the oocyte membrane. The bioactive fraction eliciting I(Cx) were peptides and was separated from two other peptidic hemolytic fractions by chromatography.

Redox signaling in macrophages

Macrophages are phagocytic cells that produce and release reactive oxygen species (ROS) in response to phagocytosis or stimulation with various agents. The enzyme responsible for the production of superoxide and hydrogen peroxide is a multi-component NADPH oxidase that requires assembly at the plasma membrane to function as an oxidase. In addition to participating in bacterial killing, ROS, which have recently been shown to be produced enzymatically by non-phagocytic cells, have been implicated in inflammation and tissue injury. These toxic effects have been largely explored over the years and these studies have overshadowed initial observations supporting a role for ROS in modulating cellular function. In recent years, it has become increasingly evident that ROS can function as second messengers and, at low levels, can activate signaling pathways resulting in a broad array of physiological responses from cell proliferation to gene expression and apoptosis. Macrophages can also produce large amounts of nitric oxide (nitrogen monoxide, *NO). *NO was first identified as the endothelial-derived relaxing factor, EDRF and its role in the signaling pathway leading to its physiological effect was rapidly established. The ability of *NO to react with O(2)(*-) to produce peroxynitrite (ONOO(-)) was later recognized. As it is diffusion-limited, this reaction is more likely to occur in cells like macrophages that produce both ROS and RNS. In this review, we will summarize the current knowledge in redox signaling, and describe more specifically studies that are particular to macrophages.

Evaluation of three-dimensional microchannel glass biochips for multiplexed nucleic acid fluorescence hybridization assays

Three-dimensional, flow-through microchannel glass substrates have a potential for enhanced performance, including increased sensitivity and dynamic range, over traditional planar substrates used in medium-density microarray platforms. This paper presents a methodology for the implementation of multiplexed nucleic acid hybridization fluorescence assays on microchannel glass substrates. Fluorescence detection was achieved, in a first instance, using conventional low-magnification microscope objective lenses, as imaging optics whose depth-of-field characteristics match the thickness of the microchannel glass chip. The optical properties of microchannel glass were shown, through experimental results and simulations, to be compatible with the quantitative detection of heterogeneous hybridization events taking place along the microchannel sidewalls, with detection limits for oligonucleotide targets in the low-attomole range.

Signaling by the respiratory burst in macrophages

During phagocytosis or stimulation with a wide variety of agents, macrophages and other phagocytic cells produce reactive oxygen species (ROS) through activation of a multicomponent NADPH oxidase. ROS production through related NADPH oxidases has recently been demonstrated in several other cell types. Furthermore, the physiological generation of ROS production has now been clearly implicated in activating signaling pathways resulting in a broad array of physiological responses from cell proliferation to gene expression and apoptosis. This brief review suggests that: 1) hydrogen peroxide and superoxide, but not the hydroxyl radical, function as second messengers; 2) antioxidant enzymes function in the "turn-off" phase of signal transduction; 3) the chemistry of thiols is critical in redox signaling; and 4) the primary physiological role of the respiratory burst in macrophages may be in redox signaling rather than microbicidal activity.

Pituitary adenylyl cyclase-activating polypeptide stimulates DNA synthesis but delays maturation of oligodendrocyte progenitors

The neuropeptide pituitary adenylyl cyclase-activating peptide (PACAP) and one of its receptors (PAC(1)) are expressed in embryonic neural tube, where they appear to regulate neurogenesis and patterning. We now show that PAC(1) gene expression is also present in neonatal rats in the ventricular and subventricular zones and in the optic chiasm, areas that are rich in oligodendrocyte (OL) progenitors (OLP). Because actions of PACAP on OLP have not been reported, we examined the effects of PACAP on the proliferation of purified OLP in culture and on myelinogenesis in cerebellar slices. Northern analyses on total RNA from purified glial cell subtypes revealed an abundant 7 kb hybridizing transcript in OLP, which was confirmed to correspond to the PAC(1) receptor by reverse transcription-PCR. The presence of this receptor was also corroborated by radioligand binding and cAMP assay. In cultured OL, receptor density decreased during maturation but was partially counterbalanced by the appearance of sites that bound both PACAP and the related peptide vasoactive intestinal peptide. PACAP increased DNA synthesis in OLP cultures almost twofold and increased the bromodeoxyuridine-labeling index in O4-positive OLP. PACAP treatment also resulted in decreased sulfate incorporation into sulfatide in cultures of differentiating OL. The PACAP effect on sulfatide synthesis was fully reproduced in a cerebellar explant model. These findings indicate that PACAP may act at two stages during OL development to (1) stimulate proliferation and (2) delay maturation and/or myelinogenesis.

Mice deficient for spermatid perinuclear RNA-binding protein show neurologic, spermatogenic, and sperm morphological abnormalities

Spermatid perinuclear RNA-binding protein (SPNR) is a microtubule-associated RNA-binding protein that localizes to the manchette in developing spermatids. The Spnr mRNA is expressed at high levels in testis, ovary, and brain and is present in these tissues in multiple forms. We have generated a gene trap allele of the murine Spnr, named Spnr(+/GT). Spnr(GT/GT) mutants show a high rate of mortality, reduced weight, and an abnormal clutching reflex. In addition to minor anatomical abnormalities in the brain, males exhibit defects in spermatogenesis that include a thin seminiferous epithelium and disorganization of spermatogenesis. Most of the sperm from mutant males display defects in the flagellum and consequently show decreased motility and transport within the oviducts. Furthermore, sperm from mutant males achieve in vitro fertilization less frequently. Our findings suggest that SPNR plays an important role in normal spermatogenesis and sperm function. Thus, the Spnr(GT/GT) mutant male mouse provides a unique model for some human male infertility cases.

Assembly of vault-like particles in insect cells expressing only the major vault protein

Vaults are the largest (13 megadalton) cytoplasmic ribonucleoprotein particles known to exist in eukaryotic cells. They have a unique barrel-shaped structure with 8-fold symmetry. Although the precise function of vaults is unknown, their wide distribution and highly conserved morphology in eukaryotes suggests that their function is essential and that their structure must be important for their function. The 100-kDa major vault protein (MVP) constitutes approximately 75% of the particle mass and is predicted to form the central barrel portion of the vault. To gain insight into the mechanisms for vault assembly, we have expressed rat MVP in the Sf9 insect cell line using a baculovirus vector. Our results show that the expression of the rat MVP alone can direct the formation of particles that have biochemical characteristics similar to endogenous rat vaults and display the distinct vault-like morphology when negatively stained and examined by electron microscopy. These particles are the first example of a single protein polymerizing into a non-spherically, non-cylindrically symmetrical structure. Understanding vault assembly will enable us to design agents that disrupt vault formation and hence aid in elucidating vault function in vivo.

Ultrasonic wedges for elastic wave bending and splitting without requiring a full band gap

We present a novel twinned-square periodic structure for ultrasonic wave bending and splitting that does not require the existence of a complete band gap and plays the role of an ultrasonic wedge. The device allows 45 degrees bending of waves and by adequately switching the twinned structure to an ultrasonic crystal 90 degrees bending is achieved. An extreme refraction law at the grain boundaries is experimentally observed.

Similarity of the patterns of sensilla on the antennae of Triatoma melanosoma and Triatoma infestans

The patterns of sensilla on the antennae of sylvatic Triatoma melanosoma Lent, Jurberg, Galvao and Carcavallo 1994 were compared with those of three samples of Triatoma infestans (Klug 1834) - one of domestic populations in Paraguay, Bolivia, Argentina and Chile, one of the sylvatic 'dark morph' from the Bolivian Chaco, and one from sylvatic sites in the Cochabamba region of Bolivia. The results of multivariate analysis indicated that, in terms of their antennal sensilla, the T. melanosoma and the 'dark morph' of T. infestans were more similar to the domestic T. infestans than to the sylvatic T. infestans from Cochabamba. As in previous molecular and genetic studies, there was no evidence to indicate that the bugs identified as T. melanosoma and those identified as T. infestans belonged to different species. The taxonomic position of T. melanosoma should therefore be reconsidered.

Vanadyl sulfate improves hepatic and muscle insulin sensitivity in type 2 diabetes

Vanadyl sulfate (VOSO(4)) is an oxidative form of vanadium that in vitro and in animal models of diabetes has been shown to reduce hyperglycemia and insulin resistance. Small clinical studies of 2- to 4-week duration in type 2 diabetes (T2DM) have led to inconsistent results. To define its efficacy and mechanism of action, 11 type 2 diabetic patients were treated with VOSO(4) at a higher dose (150 mg/day) and for a longer period of time (6 weeks) than in previous studies. Before and after treatment we measured insulin secretion during an oral glucose tolerance test, and endogenous glucose production (EGP) and whole body insulin-mediated glucose disposal using the euglycemic insulin clamp technique combined [3-(3)H]glucose infusion. Treatment significantly improved glycemic control: fasting plasma glucose (FPG) decreased from 194 +/- 16 to 155 +/- 15 mg/dL, hemoglobin A(1c) decreased from 8.1 +/- 0.4 to 7.6 +/- 0.4%, and fructosamine decreased from 348 +/- 26 to 293 +/- 12 micromol/L (all P < 0.01) without any change in body weight. Diabetics had an increased rate of EGP compared with nondiabetic controls (4.1 +/- 0.2 vs. 2.7 +/- 0.2 mg/kg lean body mass.min; P< 0.001), which was closely correlated with FPG (r = 0.56; P< 0.006). Vanadyl sulfate reduced EGP by about 20% (P< 0.01), and the decline in EGP was correlated with the reduction in FPG (r = 0.60; P< 0.05). Vanadyl sulfate also caused a modest increase in insulin-mediated glucose disposal (from 4.3 +/- 0.4 to 5.1 +/- 0.6 mg/kg lean body mass x min; P< 0.03), although the improvement in insulin sensitivity did not correlate with the decline in FPG after treatment (r = -0.16; P = NS). Vanadyl sulfate treatment lowered the plasma total cholesterol (223 +/- 14 vs. 202 +/- 16 mg/dL; P < 0.01) and low density lipoprotein cholesterol (141 +/- 14 vs. 129 +/- 14 mg/dL; P < 0.05), whereas 24-h ambulatory blood pressure was unaltered. We conclude that VOSO(4) at maximal tolerated doses for 6 weeks improves hepatic and muscle insulin sensitivity in T2DM. The glucose-lowering effect of VOSO(4) correlated well with the reduction in EGP, but not with insulin-mediated glucose disposal, suggesting that liver, rather than muscle, is the primary target of VOSO(4) action at therapeutic doses in T2DM.