Sequence comparison of avian interferon regulatory factors and identification of the avian CEC-32 cell as a quail cell line

Interferon (IFN) regulatory factor-1 (IRF-1) is a well-characterized member of the IRF family. Previously, we have cloned cDNA of several members of the chicken IRF (ChIRF) family and studied the function of ChIRF-1 in the avian cell line CEC-32. The IRF-1 proteins from primary chicken embryo fibroblasts (CEF) and CEC-32 cells differed in their electrophoretic mobility. To characterize the different forms of IRF-1 in avian cells, we compared the sequences of IRF-1 cDNA from CEC-32 cells, primary CEF, and quail fibroblasts (QEF). The deduced amino acid sequences of IRF-1 cDNA from chicken and quail show high similarity. Comparison of genomic sequences of IRF-1 and IFN consensus sequence binding protein (ICSBP) also confirm the relatedness of the members of the IRF family in quail and chicken. Based on these data, it is concluded that the avian fibroblast cell line CEC-32 is derived from quail. This conclusion is further supported by deoxynucleotide sequence comparison of a DNA fragment in an avian MHC class II gene and by fluorescence in situ hybridization (FISH) using the vertebrate telomeric (TTAGGG) repeat. Chromosome morphology and the lack of interstitial hybridization signals in macrochromosomes suggest that the CEC-32 cell line has probably been derived from Japanese quail.

Chromosomal localization of the genes encoding ALDH, BMP-2, R-FABP, IFN-gamma, RXR-gamma, and VIM in chicken by fluorescence in situ hybridization

Six structural genes encoding ALDH, BMP-2, R-FABP, IFN-gamma, RXR-gamma and VIM were mapped in the chicken by fluorescence in situ hybridization (FISH) using genomic and cDNA clones as probes. The genes were found to be located on four different macrochromosomes: chromosome 1 (IFNG and FABP), chromosome 2 (VIM and ALDH), chromosome 3 (BMP2) and a smaller macrochromosome, most probably chromosome 7 (RXRG). With the exception of IFNG none of the newly mapped sites corresponds to known orthologous regions between chicken and human chromosomes.

Effects of nicotine on bone and calciotropic hormones in growing female rats

Limited research in young adults and immature animals suggests a detrimental effect of tobacco on bone during growth. This study investigated the effects of nicotine, the major alkaloid component of tobacco, on calciotropic hormone concentrations and bone status in growing female rats. One-month-old animals received either saline (n = 10), nicotine at 3.0 mg/kg/day (n = 10), or nicotine at 4.5 mg/kg/day (n = 10) administered subcutaneously via osmotic minipumps for either 2 or 3 months. Sera, femora, tibiae, and lumbar vertebrae (3-5) were collected at necropsy. The concentrations of serum calcium, phosphorus, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, parathyroid hormone, calcitonin, and insulin-like growth factor-I were determined. Bone variables evaluated included mineral content and density (vertebrae and femora), cancellous and cortical histomorphometry (tibiae), and bone strength (vertebrae and femora). Statistically significant differences in serum mineral and hormone concentrations were not associated with nicotine dose or exposure time. No significant nicotine treatment effects were detected for bone mineral content and density, bone histomorphometry, or bone strength. We conclude that nicotine treatment for 2 or 3 months at serum concentrations in the upper range of those found in smokers has no detrimental effect on bone mass, volume, or strength in the growing rat.

Spectral karyotyping of the human colon cancer cell lines SW480 and SW620

The cell lines SW480 and SW620, derived from different stages of colon carcinoma in the same patient, have been used for a number of biochemical, immunological, and genetic studies on colon cancer. A comparative analysis of their karyotypes may identify chromosomal aberrations that might represent markers for metastatic spread. In the present study spectral karyotyping (SKY) was applied to these two colon cancer cell lines. Compared to previously reported G-banded karyotypes, 9 (SW480) and 7 (SW620) markers were identical, 3 (SW480) and 3 (SW620) markers could be redefined, 5 (SW480) and 8 (SW620) markers were newly identified, and 4 (SW480) and 5 (SW620) of the previous described markers could not be confirmed. The redefined aberrations include very complex rearrangements, such as a der(16) t(3;16;1;16;8;16; 1;16;10) and a der(18)t(18;15;17)(q12; p11p13;??) in SW620 and a der(19)t(19;8;19;5) in SW480, that have not been identified by conventional banding techniques. The resulting chromosome gains (5q11-->5q15, 7pter-->q22, 11, 13q14-->qter, 20pter-->p12, X) and losses (8pter-->p2, 18q12-->qter, Y) found in both SW480 and SW620 were in good agreement with those frequently described in colorectal tumors as primary changes in the stem cell. Abnormalities found exclusively in SW620 cells only (gains of 5pter-->5q11, 12q12-->q23, 15p13-->p11, and 16q21-->q24 and losses of 2pter-->2p24, 4q28-->qter, and 6q25-->qter) can be viewed as changes that occurred in a putative metastatic founder cell.

Activation of nuclear factor-kB in the spinal cord of experimental allergic encephalomyelitis

The DNA-binding activity of nuclear factor (NF-kB) was found to be induced in the spinal cord of rats with experimental allergic encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), from the onset of the disease. This activation of NF-kB persisted throughout the disease period and decreased thereafter in the recovery phase. Supershift analysis of NF-kB DNA-binding activity in nuclear extracts of spinal cords showed that RelA/p65 and p50 subunits but not c-Rel/p75, RelB/p68 and p52 subunits were involved in DNA binding. Pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF-kB activation, markedly inhibited the in vivo activation of NF-kB in the spinal cord of EAE rats and attenuated the clinical symptoms of EAE. These studies suggest that activation of NF-kB plays an important role in the pathogenesis of EAE and inhibitors of NF-kB activation may have therapeutic importance in MS.

Linkage and family-based association study of schizophrenia and the synapsin III locus that maps to chromosome 22q13

The human synapsin III gene (synapsin III) is a member of a neuron-specific phosphoprotein gene family involved in short-term neurotransmitter release. We mapped synapsin III to chromosomal region 22q13 (13.1-13.31) by fluorescence in situ hybridization, a region that has been identified as a potential schizophrenia susceptibility locus. The dinucleotide repeat marker D22S280 located in intron 5 of synapsin III was genotyped in a linkage and family-based association study to assess the role of the synapsin III locus in the etiology of schizophrenia. In 12 pedigrees with periodic catatonia comprising 135 individuals, we found exclusion of linkage of marker D22S280 using lod score analysis with autosomal dominant/recessive models as well as affected only LOD score methods with dominant/recessive models. In a family-based association study of 61 unrelated parent-offspring trios with schizophrenia (according to the the Diagnostic and Statistical Manual of Mental Disorders, fourth edition [DSM-IV, American Psychiatric Association, 1994]), we found no association of individual D22S280 alleles to disease. Results of a multiallelic transmission/disequilibrium test (TDT(max) = 3.00; P = 0.55) challenged the possibility that D22S280 alleles appear with DSM-IV schizophrenia more frequently than expected. In addition, no evidence for gender differences or parent-of-origin effects were found. Thus, the synapsin III locus at chromosome 22q13 is not likely to contain a schizophrenia susceptibility gene.

Characterization of a new aberration of the human Y chromosome by banding methods and DNA restriction endonuclease analysis

Comparative cytogenetic analyses were performed with ten different banding methods on a previously undescribed, inherited structural aberration of a Y chromosome, and the results compared with those of normal Y chromosomes occurring in the same family. The value of the individual staining techniques in investigations of Y chromosomal aberrations is emphasized. The aberrant Y chromosome analyzed can be formally derived from an isodicentric Y chromosome for the short arm with a very terminal long-arm breakpoint, in which the centromere, an entire short arm, and the proximal region on one long arm was lost. This interpretation was confirmed by determining the amount of the two Y-specific DNA sequences (2.1 and 3.4 kb in length) by means of Hae III restriction endonuclease analysis. The karyotype-phenotype correlations in the men with this aberrant Y chromosome, especially the fertility dysfunctions (oligoasthenoteratozoospermia, cryptozoospermia), are discussed. The possibility of the existence of fertility factors involved in the control of spermatogenesis within the quinacrine-bright heterochromatic region of the Y long arm is presented.

Transthoracic echocardiography for perioperative haemodynamic monitoring

Transoesophageal echocardiography (TOE) is valuable for perioperative monitoring in patients at risk from haemodynamic disturbance. However, its use is not practicable in patients undergoing surgical procedures under regional anaesthesia. We describe two cases showing that transthoracic echocardiography (TTE) has the same advantages as TOE and thus may be valuable for monitoring awake patients. TTE should be considered when extended perioperative haemodynamic monitoring is needed but TOE is not possible.

Characterization of the human and mouse HEY1, HEY2, and HEYL genes: cloning, mapping, and mutation screening of a new bHLH gene family

Many basic helix-loop-helix (bHLH) transcription factors are known as key regulators of embryonic development or differentiation in various species. We have isolated and characterized three new hairy-related bHLH transcription factor genes from mouse and human (hairy and Enhancer-of-split related with YRPW motif; HEY1, HEY2, and HEYL). All three HEY genes have a similar genomic structure with five exons. Together with a highly related Drosophila homologue, they form a new bHLH gene subfamily that is different from both hairy and the known vertebrate Hes and Her genes. While the overall structure with the bHLH domain, Orange domain, and WRPW motif is similar, the last motif is changed to KPYRPWG in Hey1/2 and absent in HeyL. This and other sequence features suggest Hey proteins to have unique functional properties. The genes were mapped by fluorescence in situ hybridization and RH mapping to the following human chromosomes: (HEY1) 8q21, (HEY2) 6q21, and (HEYL) 1p34.3. Based on expression patterns and map location, HEY genes are candidates for several human or mouse disease loci. However, initial screening of DNA from affected individuals for two human disorders and four mouse mutants did not reveal any diagnostic alterations in the coding regions.

Amplification of a long terminal repeat-like element on the Y chromosome of the platyfish, Xiphophorus maculatus

The platyfish (Xiphophorus maculatus), in which sex chromosomes are evident from stable and predictable inheritance of sex, is one of the best-studied lower vertebrates with respect to sex determination. In order to identify the structural equivalent for this in the karyotype, which does not contain heteromorphic pairs of chromosomes, two sex-linked molecular probes were used for fluorescent in situ hybridization analysis. One probe, derived from the melanoma oncogene locus ONC-Xmrk, stained both the X and the Y chromosome. This cytogenetic analysis mapped the sex-determining locus to the subtelomeric region of a medium-sized telocentric chromosome. Another probe, a repetitive element (XIR), specifically labeled the Y chromosome in metaphase spreads and in interphase nuclei. The sex chromosomes of X. maculatus can be considered to be at an early stage of evolution of gonosomes. Expansion of the XIR repeat is obviously one of the earliest of the molecular events that lead to divergence of the Y chromosome and recombinational isolation of the sex-determining locus.

Radiation treatment for cervical esophagus: patterns of practice study in Canada, 1996

PURPOSE

To assess the patterns of practice among Canadian radiation oncologists who treat esophageal cancers, using a trans-Canada survey, completed at the end of 1996.

METHODS AND MATERIALS

One of 3 case presentations of different stages of cervical esophageal cancer was randomly assigned and sent to participating radiation oncologists by mail. Respondents were asked to fill in questionnaires regarding treatment techniques and to outline target volumes for the boost phase of radiotherapy. Radiation oncologists from 26 of 27 (96%) of all Canadian centers participated.

RESULTS

High-energy X-rays (>/= 10 MV) were employed by 68% of the respondents in part of the treatment course. The majority (83%) of the radiation oncologists used at least two phases of treatment. Very few, 10 of 59 (17%), responses started with multifield treatment. The most frequently used prescription dose was 60 Gy/30 fractions/6 weeks, given with concurrent chemotherapy. Dose prescriptions were to the isocenter in 39 of 48 (81%) or to a particular isodose line in 9 of 48 (19%) of respondents.

CONCLUSION

There was a variety of radiation treatment techniques in this trans-Canada survey. The majority of the patients had combined cisplatin-based chemoradiation. The isocenter was not used consistently as a dose prescription point.

Gross chromosomal rearrangements and genetic exchange between nonhomologous chromosomes following BRCA2 inactivation

Cancer-causing mutations often arise from gross chromosomal rearrangements (GCRs) such as translocations, which involve genetic exchange between nonhomologous chromosomes. Here we show that murine Brca2 has an essential function in suppressing GCR formation after chromosome breakage. Cells that harbor truncated Brca2 spontaneously incur GCRs and genomic DNA breaks during division. They exhibit hypersensitivity to DNA damage by interstrand cross-linkers, which even at low doses trigger aberrant genetic exchange between nonhomologous chromosomes. Therefore, genetic instability in Brca2-deficient cells results from the mutagenic processing of spontaneous or induced DNA damage into gross chromosomal rearrangements, providing a mechanistic basis for cancer predisposition.

Structure-function analysis of SUV39H1 reveals a dominant role in heterochromatin organization, chromosome segregation, and mitotic progression

SUV39H1, a human homologue of the Drosophila position effect variegation modifier Su(var)3-9 and of the Schizosaccharomyces pombe silencing factor clr4, encodes a novel heterochromatic protein that transiently accumulates at centromeric positions during mitosis. Using a detailed structure-function analysis of SUV39H1 mutant proteins in transfected cells, we now show that deregulated SUV39H1 interferes at multiple levels with mammalian higher-order chromatin organization. First, forced expression of full-length SUV39H1 (412 amino acids) redistributes endogenous M31 (HP1beta) and induces abundant associations with inter- and metaphase chromatin. These properties depend on the C-terminal SET domain, although the major portion of the SUV39H1 protein (amino acids 89 to 412) does not display affinity for nuclear chromatin. By contrast, the M31 interaction surface, which was mapped to the first 44 N-terminal amino acids, together with the immediately adjacent chromo domain, directs specific accumulation at heterochromatin. Second, cells overexpressing full-length SUV39H1 display severe defects in mitotic progression and chromosome segregation. Surprisingly, whereas localization of centromere proteins is unaltered, the focal, G(2)-specific distribution of phosphorylated histone H3 at serine 10 (phosH3) is dispersed in these cells. This phosH3 shift is not observed with C-terminally truncated mutant SUV39H1 proteins or with deregulated M31. Together, our data reveal a dominant role(s) for the SET domain of SUV39H1 in the distribution of prominent heterochromatic proteins and suggest a possible link between a chromosomal SU(VAR) protein and histone H3.

Essential role of tyrosine 229 of the oxaloacetate decarboxylase beta-subunit in the energy coupling mechanism of the Na(+) pump

The membrane-bound beta-subunit of oxaloacetate decarboxylase from Klebsiella pneumoniae catalyzes the decarboxylation of carboxybiotin, which is coupled to Na(+) translocation and consumes a periplasmically derived proton. Upon site-directed mutagenesis of 20 polar and/or conserved residues within putative membrane-integral regions, the specific oxaloacetate decarboxylase activities were reduced to various extents, but only the enzyme with a Y229F mutation was completely inactive. We propose that Y229 is part of the network by which the proton of S382 is delivered to carboxybiotin, where it is consumed upon catalyzing the immediate decarboxylation of this acid-labile compound. Unlike S382 or D203, Y229 appears to be not involved in Na(+) binding, because in the Y229F orY229A mutants, the beta-subunit was protected from tryptic digestion by 50 mM NaCl like in the wild-type enzyme. Oxaloacetate decarboxylase with a betaC291E mutation was unstable in the absence of Na(+) and dissociated into an alpha-gamma subcomplex and the beta-subunit. The enzyme could only be isolated in the presence of 0. 5 M NaCl. These results are consistent with the notion that the beta-subunit changes its conformation upon Na(+) binding.

Identification and chromosomal localization of murine ORC3, a new member of the mouse origin recognition complex

A new member of the murine origin recognition complex (ORC) related to Saccharomyces cerevisiae ORC3 has been cloned. Transcription of ORC3 is not suppressed in mouse NIH3T3 fibroblasts made quiescent by serum starvation. The transcription level of the ORC3 gene is constantly high in all phases of the cell cycle. Murine ORC3 protein contains a putative nuclear localization signal and a non-basic helix-loop-helix motif. Both motifs are conserved in eukaryotes. A potential dimerization partner of ORC3p in the murine ORC complex is ORC1p which also contains an HLH motif. This HLH motif is also highly conserved in all eukaryotic ORC1 proteins. Comparison of murine ORC3p with other ORC3-related proteins shows high amino acid homology and motif conservation leading to the conclusion that ORC3p is part of the initiation machinery conserved in eukaryotes. The mouse ORC3 gene Orc3 was assigned to mouse chromosome 4A3 by fluorescence in situ hybridization (FISH) analysis.

Molecular evidence for genus level diversity of bacteria capable of catalyzing anaerobic ammonium oxidation

Recently, a bacterium capable to oxidize ammonium anaerobically at a high rate was identified as novel member of the Planctomycetales (Strous, M., Fuersi, J. A., Kramer, E. H. M., Logemann, S., Muyzer, G., van de Pas-Schoonen, K. T., Webb, R. I., Kufnen, J. G., and Jetten, M. S. M.: Nature 400, 446-449, 1999). Here we investigated the microbial community structure of a trickling filter biofilm with a high anaerobic ammonium oxidation activity. Fluorescence in situ hybridization (FISH) with a set of nine probes designed for specific identification of the recently described anaerobic ammonium oxidizer demonstrated that only one probe hybridized to bacteria within the biofilm. For phylogenetic characterization of putative biofilm anaerobic ammonium oxidizers a full-cycle 16S rDNA approach was performed by using a Planctomycetales-specific forward primer for PCR amplification. Of the twenty-five 16S rDNA fragments (1364 bp in length) amplified from the biofilm, nine were affiliated to the Planctomycetales. Comparative analysis showed that these sequences were more than 98.9% similar to each other but only distantly related to the previously recognized anaerobic ammonium oxidizer (below 91% similarity) and all other organisms represented in public 16S rRNA databases (similarities of below 79%). The retrieved sequences and the previously recognized anaerobic ammonium oxidizer represent two well-separated groups of a deep-branching lineage within the Planctomycetales. Quantitative FISH analysis with a newly designed specific probe showed that the novel bacterium, provisionally classified as "Candidatus Kuenenia stuttgartiensis" constituted the dominant fraction of the biofilm bacteria. In situ probing revealed that ammonia-oxidizing bacteria of the beta-subclass of Proteobacteria were also present, albeit in significant smaller amounts, within the anoxic biofilm. Comparative sequence analysis of a stretch of the gene encoding ammonia-monooxygenase (amoA) demonstrated the occurrence of the DNA of at least three different populations of beta-subclass ammonia oxidizers within the biofilm.

p53 mutations in hairy cell leukemia

We have studied the frequency of p53 mutations in genomic DNA extracted from peripheral blood or the spleen of 61 patients with hairy cell leukemia using PCR-SSCP and automated cycle sequencing. We identified exon 5-8 mutations in 17 cases, corresponding to a frequency of 28%. In four cases, mutations were localized in exon 5; one patient with atypical HCL had a mutation in exon 6 at the 3' boundary; five cases showed mutations in exon 7, while exon 8 was found to be mutated in seven cases. The mutations found could be divided into three major categories: structural (n=9), inactivating (n= 6), and neutral (n= 2) mutations. None of the three transitions found occurred at CpG dinucleotides. The rate of p53 mutations found in this large cohort of HCL patients is unexpectedly high as in other non-Hodgkin lymphomas p53 mutations predict for poor treatment outcome. The character of the mutations we have found is entirely different from that described in other hematologic malignancies.

A molecular coupling mechanism for the oxaloacetate decarboxylase Na+ pump as inferred from mutational analysis

The oxaloacetate decarboxylase Na+ pump consists of subunits alpha, beta, and gamma, and contains biotin as the prosthetic group. Membrane-bound subunit beta catalyzes the decarboxylation of carboxybiotin coupled to Na+ translocation, and consumes a periplasmically derived proton. Site-directed mutagenesis of conserved amino acids of transmembrane helix VIII indicated that residues N373, G377, S382, and R389 are functionally important. The polar side groups of these amino acids may constitute together with D203 a network of ionizable groups which promotes the translocation of Na+ and the oppositely oriented H+ across the membrane. Evidence is presented that two Na+ ions are bound simultaneously to subunit beta during transport with D203 and S382 acting as binding sites. Sodium ion binding from the cytoplasm to both sites elicits decarboxylation of carboxybiotin, and a conformational switch exposes the bound Na+ ions toward the periplasm. After dissociation of Na+ and binding of H+, the cytoplasmically exposed conformation is regained.

Mitotic phosphorylation of SUV39H1, a novel component of active centromeres, coincides with transient accumulation at mammalian centromeres

Centromeres of eukaryotes are frequently associated with constitutive heterochromatin and their activity appears to be coregulated by epigenetic modification of higher order chromatin. Recently, we isolated murine (Suv39h1) and human (SUV39H1) homologues of the dominant Drosophila suppressor of position effect variegation Su(var)3-9, which is also related to the S. pombe silencing factor Clr4. We have shown that mammalian Su(var)3-9 homologues encode novel centromeric proteins on metaphase-arrested chromosomes. Here, we describe a detailed analysis of the chromatin distribution of human SUV39H1 during the cell cycle. Although there is significant heterochromatic overlap between SUV39H1 and M31 (HP1(beta)) during interphase, mitotic SUV39H1 displays a more restricted spatial and temporal association pattern with metaphase chromosomes than M31 (HP1(beta)), or the related HP1(α) gene product. SUV39H1 specifically accumulates at the centromere during prometaphase but dissociates from centromeric positions at the meta- to anaphase transition. In addition, SUV39H1 selectively associates with the active centromere of a dicentric chromosome and also with a neocentromere. Interestingly, SUV39H1 is shown to be a phosphoprotein with modifications at serine and, to a lesser degree, also at threonine residues. Whereas SUV39H1 steady-state protein levels appear constant during the cell cycle, two additional phosphorylated isoforms are detected in mitotic extracts. This intriguing localisation and modification pattern would be consistent with a regulatory role(s) for SUV39H1 in participating in higher order chromatin organisation at mammalian centromeres.

Fast and type-specific analysis of herpes simplex virus types 1 and 2 by rapid PCR and fluorescence melting-curve-analysis

Diagnosis of central nervous system (CNS) infection with herpes simplex virus (HSV) requires sensitive and rapid techniques. PCR therefore is considered to be the diagnostic gold standard in these cases. However, current PCR protocols are time-consuming and labor-intensive. In addition, the need for post-amplification manipulations increases the risk of laboratory contaminations with amplified products. In order to improve conventional PCR techniques we compared our current semiautomated HSV-PCR-ELISA assay with a new micro-volume rapid-cycle PCR system that combines real-time monitoring and fluorescence melting-curve analysis without the need for post-amplification sample manipulations. Spiking experiments with supernatants of tissue culture-grown HSV type 1 (HSV-1) and type 2 (HSV-2) in HSV-negative control cerebrospinal fluid (CSF) and sterile water revealed that the new rapid cycle PCR protocol is as sensitive and specific as the PCR-ELISA. Furthermore, a mismatch (G:T) within the probe-targeted region of the HSV-2 glycoprotein B gene decreases the probe/product melting temperature (Tm) from 69 degrees C for HSV-1 to 64 degrees C for HSV-2, enabling the simultaneous identification of the two HSV genotypes by melting-curve analysis within one run. This type specificity of the system was confirmed with 30 genital swabs previously analyzed for the presence of HSV-1/2 in cell culture. While our current PCR-ELISA method needs up to 1 day from sample preparation to result generation, the new procedure takes only 1 h. We consider this system as a promising new tool for the analysis of HSV DNA in CSF and in other human body fluids as well as for the diagnosis of other infectious agents where rapid diagnosis, high sensitivity and specificity are required.

Atomic-scale structure and catalytic reactivity of the RuO(2)(110) surface

The structure of RuO(2)(110) and the mechanism for catalytic carbon monoxide oxidation on this surface were studied by low-energy electron diffraction, scanning tunneling microscopy, and density-functional calculations. The RuO(2)(110) surface exposes bridging oxygen atoms and ruthenium atoms not capped by oxygen. The latter act as coordinatively unsaturated sites-a hypothesis introduced long ago to account for the catalytic activity of oxide surfaces-onto which carbon monoxide can chemisorb and from where it can react with neighboring lattice-oxygen to carbon dioxide. Under steady-state conditions, the consumed lattice-oxygen is continuously restored by oxygen uptake from the gas phase. The results provide atomic-scale verification of a general mechanism originally proposed by Mars and van Krevelen in 1954 and are likely to be of general relevance for the mechanism of catalytic reactions at oxide surfaces.

Intussusceptive angiogenesis: its role in embryonic vascular network formation

Intussusceptive angiogenesis is a novel mode of blood vessel formation and remodeling, which occurs by internal division of the preexisting capillary plexus without sprouting. In this study, the process is demonstrated in developing chicken eye vasculature and in the chorioallantoic membrane by methylmethacrylate (Mercox) casting, transmission electron microscopy, and in vivo observation. In a first step of intussusceptive angiogenesis, the capillary plexus expands by insertion of numerous transcapillary tissue pillars, ie, by intussusceptive microvascular growth. In a subsequent step, a vascular tree arises from the primitive capillary plexus as a result of intussusceptive pillar formation and pillar fusions, a process we termed "intussusceptive arborization." On the basis of the morphological observations, a 4-step model for intussusceptive arborization is proposed, as follows: phase I, numerous circular pillars are formed in rows, thus demarcating future vessels; phase II, formation of narrow tissue septa by pillar reshaping and pillar fusions; phase III, delineation, segregation, growth, and extraction of the new vascular entity by merging of septa; and phase IV, formation of new branching generations by successively repeating the process, complemented by growth and maturation of all components. In contrast to sprouting, intussusceptive angiogenesis does not require intense local endothelial cell proliferation; it is implemented primarily by rearrangement and attenuation of the endothelial cell plates. In summary, transcapillary pillar formation, ie, intussusception, is a central and probably widespread process, which plays a role not only in capillary network growth and expansion (intussusceptive microvascular growth), but also in vascular plexus remodeling and tree formation (intussusceptive arborization).

Critical factors in the radioimmunoassay of endothelin-1, endothelin-3, and big endothelin-1 in human plasma

The possible diagnostic or prognostic significance of changes in circulating level of endothelins in a variety of pathological conditions is currently of interest. Unfortunately, no consensus regarding optimization of sensitivity and extraction procedures for the reliable radioimmunoassay of endothelin-1 (ET-1), big endothelin-1 (BigET-1), and endothelin-3 (ET-3) currently exists. The object of the present study was to evaluate aspects of currently used extraction and assay procedures that limit accurate determination of ET in human plasma and define criteria to reduce variability. Critical parameters include the selectivity of commercial antibodies and the ability to remove interfering material after Sep-Pak absorption by selective washing with 24% ethanol in 4% acetic acid or methylene chloride in 0.1% trifluoroacetic acid. Assay sensitivity and specificity in the physiological range is improved by optimizing total binding parameters for the antibodies to give approximately 15-20% binding of radiolabeled peptide. With these modifications normal plasma values for ET-1, BigET-1, and ET-3 averaged 1.7 +/- 0.06, 2.5 +/- 0.3, and 5.8 +/- 0.2 pg/ml, respectively. These data suggest that such modifications may help to resolve many of the earlier difficulties concerning the role of ET under normal and pathological conditions.

Noninvasive determination of genome size and ploidy level in fishes by flow cytometry: detection of triploid Poecilia formosa

BACKGROUND

In order to understand the evolutionary significance of single triploids among the mostly diploid Poecilia formosa we have developed a simple, noninvasive technique for DNA content and ploidy determination.

METHODS

From dorsal fin clips of 14 different fish species single cell suspensions were obtained by chopping the material in 2.1% citric acid/0.5% Tween20, passing it through a 0. 6-gauge needle and incubating it for 20 min at room temperature (RT) with gentle agitation. After overnight fixation in 70% ethanol, the cells were treated with 1ml 0.5% pepsin/0.1 M HCl for 15 min at RT before adding DAPI to a final volume of 2 ml. The cells were stained for 1-3 h and then analyzed by flow cytometry.

RESULTS

We obtained good measurements with CVs ranging from 1.23% to 3.36%. The poeciliid species measured contain from 1.6 to 2.0 pg/nucleus, Oryzias latipes (Medaka) exhibits a nuclear DNA content of 2.2 pg, Danio rerio (zebrafish) 4.6 pg, Tetraodon fluviatilis (freshwater fugu) 0.70 pg. All values except zebrafish are in good agreement with the literature.

CONCLUSIONS

The identification of living specimens of different ploidy for breeding experiments, behavioral studies and tissue transplantations is now made possible. With slight modifications the method can be extended to a field technique, providing therefore a useful tool for a variety of researchers.