PubMed Health⌕ Search

Biomedical subjects

M Vaiman

Publications and source records attributed to M Vaiman.

At least 19 recordsLinked to original sources
PubMed2006

The endoscopic Draf II frontal sinusotomy: non-navigated approach.

OBJECTIVE: Endoscopic endonasal Draf II frontal sinusotomy is indicated for a variety of pathologies such as mucocele and non-responsive chronic frontal sinusitis. However, this approach is challenged and controversial. The objectives were to evaluate the advantages, disadvantages, indications, and rate of complications of this approach, without the use of a navigation system. METHODS: The files and computed tomography (CT) scans of 25 patients who underwent endoscopic endonasal Draf II sinusotomy at Assaf Harofeh Medical Center between 1999 and 2002 were reviewed. RESULTS: Thirty-one frontal sinuses were operated on and follow-up was between 18 and 62 months (average 30.3). Twenty-two sinuses (71%) had previous surgery. The Draf II procedure was used in 3.7% of all cases during the survey period. The most frequent indication for surgery was inflammation (48%) followed by mucocele (28%). In all but 2 sinuses (93%), the frontal floor between the lamina papyracea and the middle concha was drilled out. Twenty-four patients (96%) were successfully ventilated. No major complications were noted. CONCLUSIONS: The Draf II approach can be used safely and successfully without a navigation system, including cases of revision endoscopic sinus surgery. Correct interpretation of the surgical field and a CT scan are crucial for success. Careful patient selection is essential for this procedure.

Adolescent↗
PubMed2001

Sequence of the pig major histocompatibility region containing the classical class I genes.

A segment comprising 307,078 nucleotides of the pig major histocompatibility complex (SLA) was completely sequenced. The segment corresponded to the entire SLA classical class I-containing region of the serologically defined SLA H01 haplotype. In all, 11 genes were characterized, comprising 7 class I genes located on the centromeric part of the sequence (SLA-1, 2, 3, 4, 5, 9, and 11) and 4 ring finger-related family genes located on its telomeric part. No member of one family was intermingled with a member of the other or with any third-party gene. All class I genes except SLA-11 were similarly orientated. The SLA-1, 2, and 3 genes displayed both promoter and overall coding regions compatible with normal functions. The SLA-4, 11, and 9 genes were considered pseudogenes because they exhibited marked anomalies. Although the SLA-5 gene had a complete coding region, it displayed mutations in promoter elements which could modify its expression. The great molecular similarity observed among the class I genes extended far outside them, and resulted from segmental duplications. The ring finger genes exhibited great homology with their human counterparts. In pig, one of these genes appeared to correspond to a complete gene which in humans is probably a pseudogene. In all, the 11 genes characterized span about 20% of the total sequence. The remaining 80% consists of interspersed repeat elements. The present results, together with the sequence previously reported involving the SLA class I-related genes, open the way for a better understanding of pig MHC organization.

Alleles↗
PubMed2001

Sequence of the swine major histocompatibility complex region containing all non-classical class I genes.

A segment of 158,063 nucleotides of the pig major histocompatibility complex (SLA) and corresponding to the junction of the class I and class III regions was sequenced entirely. The centromeric part of the segment contained six class III genes including the three tumor necrosis factor genes, while the telomeric part contained three genes belonging to the class I region. The order and the molecular organization of these genes were exactly conserved in the SLA and HLA complexes, except for the SC1 gene which displayed a shift of the reading frame in swine. The cluster of the three SLA class I-related genes (Ib) and the MIC1 and MIC2 genes were located in the middle of the segment, in the following order from the centromeric side onwards, SLA-6, SLA-7, SLA-8, MIC-1 and MIC-2. All three SLA Ib genes displayed an overall molecular structure compatible with the expression of membrane-anchored glycoproteins. The SLA-7 and SLA-8 genes bear greater resemblance than to the SLA-6 gene. Six SLA-6 alleles have been previously defined differing each from the other by unique point mutations. One of them, appeared to have arisen through the occurrence of a gene conversion event in which the SLA-7 gene served as template. Only MIC-2 gene might be functional, the second MIC-1 gene being truncated. In all, the 14 genes characterized spans 37% of the total sequence. The remaining 63% nucleotides comprised a number of repeat DNA motives, including LINE fragments, SINEs, microsatellites, and also numerous nucleotide stretches not yet defined in swine.

Alleles↗
PubMed1999

Spatial arrangement of pig MHC class I sequences.

Bacterial artificial chromosome (BAC) clones were assigned within the pig major histocompatibility complex (Mhc) by polymerase chain reaction-screening and Southern blot hybridization using sequence-tagged site (STS) markers and BAC end-rescued sequences. In all, 35 BAC clones were discovered containing 12 anchor genes of the SLA class I region and two genes of the SLA class III region. Twenty of these 35 clones comprised two distinct class I gene clusters, each spanning about 100 kilobases. One cluster enclosed three class I related genes (SLA-6 to -8) and two genes (MIC-1 and MIC-2) more distantly related to class I. The other cluster enclosed typical class I genes, of which three (SLA-1, -2, and -3) were transcribed by fibroblasts homozygous for the H01 haplotype which we used to construct a pig BAC library. Ordered clones are certainly helpful in isolating agronomically, biologically, and medically important genes. They would also be useful for inducing genetic modifications in pig cell lines.

Animals↗
PubMed1999

The major histocompatibility complex in swine.

In swine, the major histocompatibility complex (Mhc) or swine leukocyte antigen (SLA) is located on chromosome 7 and divided by the centromere. Thus, the telomeric class I and more centromeric class III regions are located on the p arm and the class II region is located on the q arm. The SLA region spans about 2 Mb, in which more than 70 genes have so far been characterized. Despite its division by the centromere, the spatial relationships between the genes in the class II and class III regions, and between the well-conserved non-class I genes of the class I region, are similar to those found in the human HLA complex. On the other hand, no orthologous relationships have been found between the Mhc class I genes in man and swine. In swine, the 12 SLA class I sequences constitute two distinct clusters. One cluster comprises six classical class I-related sequences, while the other comprises five class I-distantly related sequences including two swine homologous genes of the HLA Mhc class I chain-related gene (MIC) sequence family. The number of functional SLA classical class I genes, as defined by serology, probably varies from one to four, depending on the haplotype. Some of the SLA class I-distantly related sequences are clearly transcribed. As regards the SLA class II genes, some of them clearly code for at least one functional SLA-DR and one SLA-DQ heterodimer product, but none code for any DP product. The amino acid alignment of the variable domains of 33 SLA classical class I chains, and 62 DR beta and 20 DQ beta chains confirmed the exceptionally polymorphic pattern of these polypeptides. Among the class II genes, the genes are either monomorphic, like the DRA gene, or oligomorphic, like the DQA genes. In contrast, the DRB and DQB genes display considerable polymorphism, which seems more marked in DRB than DQB genes.

Amino Acid Sequence↗
PubMed1999

Construction of a swine BAC library: application to the characterization and mapping of porcine type C endoviral elements.

A porcine bacterial artificial chromosome (BAC) library was constructed using the pBeloBAC11 vector. It comprised 107,520 clones with an average insert size of 135 kb, representing an almost fivefold coverage of the swine haploid genome. Screening of the library allowed recovery of one to eight clones for 142 unique markers located all over the genome, while it failed for only one marker. About 4% chimeric clones were found. The library was also screened for the protease gene of type C porcine endoviral sequences (PERVs), and 62 clones were recovered, all but two of which contained one protease gene. We found 20 protease sequences (PERV-1 to PERV-20) which, despite differing by point mutations, were all coding sequences. The most frequent sequence, PERV-2, was 100% similar to a protease sequence expressed in the porcine PK-15 cell line. Most of the clones harbored envelope genes. Thirty-three BAC clones were mapped by fluorescence in situ hybridization to 22 distinct locations on 14 chromosomes, including the X and Y chromosomes. These overall results indicate that there is generally one PERV copy per integration site. Although PERV sequences were not tandemly arranged, clusters of integration sites were observed at positions 3p1.5 and 7p1.1. Southern blot experiments revealed 20-30 PERV copies in the Large White pig genome studied here, and variations in PERV content among pigs of different breeds were observed. In conclusion, this BAC collection represents a significant contribution to the swine large genomic DNA cloned insert resources and provides the first detailed map of PERV sequences in the swine genome. This work is the first step toward identification of potential active sites of PERV elements.

Amino Acid Sequence↗
PubMed1999

In vivo regulation of von willebrand factor synthesis: von Willebrand factor production in endothelial cells after lung transplantation between normal pigs and von Willebrand factor-deficient pigs.

To evaluate the regulation of plasma von Willebrand factor (vWF) and its in situ production by endothelial cells (ECs), 12 swine leukocyte antigen (SLA)-compatible left lung transplantations were performed. Normal lungs were transplanted into 10 pigs homozygous for von Willebrand disease and into 2 normal pigs. Additionally, 1 normal pig underwent pneumonectomy, and 1 SLA-incompatible lung transplantation between normal pigs was performed. None of the transplanted animals received immunosuppressive therapy. Plasma vWF level was evaluated by ELISA and multimeric pattern. EC vWF content was assessed by immunohistochemistry. Global hemostasis was assessed by standardized ear bleeding time. Six of 12 SLA-compatible lung transplantations and the incompatible transplantation were successful and were used for the study. The functions and the viability of ECs, reflected by their ability to produce vWF and normal multimeric plasma vWF pattern, were preserved in SLA-compatible and -incompatible lung transplantations. vWF production was preserved in ECs that initially synthesized it. EC constitutive and storage pathways are modulated differently according to transplantation compatibility and severity of rejection. In SLA-compatible lung transplantations without histological evidence of rejection, the production of vWF was preserved, whereas constitutive vWF secretion appeared to be altered in cases with minor histological signs of rejection. In pigs with von Willebrand disease that were transplanted with normal lungs without sign of rejection, plasma vWF was significantly increased in an amount expected from the estimated production of a normal lung. In the transplanted normal lung, there was no vWF overexpression by the ECs and no recruitment of ECs that initially did not express vWF. In SLA-incompatible transplantation, ECs were morphologically normal with increased and blurred vWF labeling, whereas plasma vWF levels remained normal, reflecting that EC activation is associated with an increased vWF production with probable diversion to storage pathway. This model depicts the changes of EC regulation of vWF secretion in pig lung transplants. However, this model cannot be directly extrapolated to human organ transplantation because animals did not receive any immunosuppressive therapy, which may be toxic to ECs.

Acute Disease↗
PubMed1998

A first map of the porcine major histocompatibility complex class I region.

A map of the SLA complex, or swine major histocompatibility complex (MHC), class I region was constructed by alignment of yeast artificial chromosomes (YACs) harboring MHC class I genes as well as anchor genes already mapped within the human MHC complex (HLA). Five YACs containing 9 anchor genes built a contig of about 1.0-1.2 Mb between the SLA class III BAT1 locus and the olfactory receptor-like genes OLF42. Ten different SLA class I sequences, including putative allelic forms of published classical and non-classical SLA class I genes, were assigned to the 400-kb enclosing centromeric part of the contig. Three additional YACs comprising the OLF89 genes and two YACs containing the butyrophilin gene were located telomeric to the contig. Comparison between the human and porcine MHC complexes showed a perfect conserved order of anchor genes, whereas no orthologous relationships were found for the class I loci.

Animals↗
PubMed1998

Porcine major histocompatibility complex.

The major histocompatibility complex in swine (swine leucocyte antigen: SLA) is located on chromosome 7 with the class I and class III regions separated by the centromere from the class II region. The overall molecular organisation of the class I and III regions is well known, but further research is needed to establish that of the class II region. Approximately sixty genes have been characterised to date, including ten tightly packed SLA class I sequences. The exact number of functional polymorphic class I genes, as defined by serology, probably varies from one to four, depending on the haplotype. At least two other distantly class I-related gene families exist. The numerous and significant associations reported between SLA haplotypes and physiological traits are described. These traits include immune responsiveness to a variety of microbes and metazoan parasites, and male and female production and reproduction performance. The results obtained suggest that selection for specific SLA haplotypes may assist in the improvement of porcine production.

Animals↗
PubMed1998

Unlike tenascin-X, tenascin-C is highly up-regulated in pig cutaneous and underlying muscle tissue developing fibrosis after necrosis induced by very high-dose gamma radiation.

Fibrosis is characterized by proliferation of fibroblasts and deposition of extracellular matrix (ECM). As alterations in the composition of ECM may account for its chronic extension, we studied the expression of the tenascin-C (TN-C) and tenascin-X (TN-X) ECM glycoproteins in our pig model of the effects of accidental exposures to radiation, in which cutaneous and muscle fibrosis developed after the induction of necrosis after a high single dose (160 Gy at the skin surface) of gamma rays. We found that, in the healed fibrotic dermis and underlying muscle fibrosis, the amount of TN-C mRNA was increased up to 18- and 39-fold, respectively, compared to normal dermis, whereas the level of TN-X mRNA remained almost unchanged. In analyses by Western blotting, the two main TN-C isoforms of 235-240 and 190-200 kDa increased up to 45- and 105-fold in fibrotic tissues, respectively. The large isoform was expressed more strongly than the smaller, although in healed fibrotic scar tissues their ratio was lower in protein than in RNA. Compared to unirradiated skin, an immunohistological study revealed stronger TN-C staining at the dermo-epidermal junction and in areas of remodeling in healed skin. An intense extracellular staining was observed around myofibroblasts in muscle fibrosis. Therefore, the gene encoding TN-C is highly up-regulated in fibrotic tissues, and mechanisms regulating the levels of TN-C variants occur at both the RNA and protein levels. Each isoform might play a distinct role in the chronic activation of fibrosis by differentially regulating mechanisms like cell adhesion, migration or proliferation.

Alternative Splicing↗
PubMed1998

Role of plasma and platelet von Willebrand factor in arterial thrombogenesis and hemostasis in the pig.

To evaluate the relative role of plasma and platelet von Willebrand factor (vWF) pools in hemostasis and arterial thrombogenesis, pigs with vW disease (vWD) were injected with vWF concentrate and/or grafted with bone marrow from a normal pig. Hemostasis was assessed by measurement of ear immersion bleeding time, factor VIII (FVIII) activity, and plasma and platelet vWF antigen levels. The thrombotic process was explored at 650 s(-1) and 1600 s(-1) in an ex vivo cylindrical perfusion chamber. Pigs with vWD exhibited a prolonged bleeding time (>30 minutes) compared with normal pigs (<5 minutes); in addition, they showed normal platelet adhesion and thrombus formation at 650 s(-1) but profoundly reduced platelet adhesion and thrombus formation at 1600 s(-1). Each experiment was performed before and 3 and 24 hours after injection of vWF concentrate. In our bleeding time study, only plasma vWF restoration induced a partial but delayed correction (24 hours postinjection), which was correlated with the highest measured level of FVIII activity. In the perfusion chamber model, restoration of plasma or platelet vWF pools resulted in similar partial correction of platelet adhesion and average thrombus size. In the perfused pigs, the maximum correction occurred 3 hours postinjection. Platelet deposition reached normal values after vWF concentrate was injected into a grafted pig. The present results suggest that when both plasma and platelet vWF levels are restored in vWD pigs, bleeding time and the thrombotic process are normalized according to different kinetics and with differing degrees of effectiveness.

Animals↗
PubMed1997

Construction of a swine YAC library allowing an efficient recovery of unique and centromeric repeated sequences.

A swine DNA genomic library was constructed in yeast artificial chromosome (YAC) using the pYAC4 vector and the AB1380 strain. The DNA prepared from two Large White males was partially digested with EcoRI and size selected after both digestion and ligation. The YAC library contained 33792 arrayed clones with an average size of 280 kb as estimated by analysis of 2% of the clones, thus representing a threefold coverage of the swine haploid genome. The library was organized in pools to facilitate the PCR screening. The complexity of the library was tested both for unique and centromeric repeated sequences. In all, 20 out of 22 primer sets allowed the characterization of one to six clones containing specific unique sequences. These sequences are known to be on Chromosomes (Chrs) 1, 2, 5, 6, 7, 8, 13, 14, 15, 17, and X. Eight additional clones carrying centromeric repeat units were also isolated with a single primer set. The sequencing of 37 distinct repeat units of about 340 bp subcloned from these eight YACs revealed high sequence diversity indicating the existence of numerous centromeric repeat unit subfamilies in swine. Furthermore, the analysis of the restriction patterns with selected enzymes suggested a higher order organization of the repeat units. According to preliminary FISH experiments on a small number of randomly chosen YACs and YACs carrying specific sequences, the chimerism appeared to be low. In addition, primed in situ labeling experiments favored the idea that the YACs with centromeric repeat sequences were derived from a subset of metacentric and submetacentric chromosomes.

Animals↗
PubMed1997

Swine centromeric DNA repeats revealed by primed in situ (PRINS) labeling.

In swine, distinct centromeric satellite DNA families have been described that correspond to either all the metacentric chromosomes except the Y (Mc1) or all the acrocentric chromosomes (Ac2). Using primed in situ (PRINS) labeling, we show here that primers derived from various sequences specifically label the centromeres of different subgroups of chromosomes. Among five primers derived from centromeric sequences of acrocentric chromosomes reported to be very homogeneous, four recognize all the acrocentric chromosomes, whereas one labels prominently chromosome 17. For the metacentric chromosomes, six primers have been derived from several divergent sequences. Among these primers, two recognize all the metacentric chromosomes except 5, 10, and 12. Three other primers label small subsets of metacentric chromosomes, including the X and one or two additional chromosomes. The last primer is specific to chromosome 1. These preliminary results suggest that it should be possible to define specific primers for almost every swine chromosome. Already, some of the primers reported here permit a distinction between swine chromosomes difficult to differentiate without banding, such as the X chromosome and chromosome 9. Therefore, the PRINS technique using centromeric motifs constitutes an additional tool for cytogenetic studies in swine.

Animals↗
PubMed1996

A detailed physical map of the porcine major histocompatibility complex (MHC) class III region: comparison with human and mouse MHC class III regions.

A detailed physical map of the porcine MHC class III region on Chr 7 was constructed with a panel of probes in a series of hybridizations on genomic pulsed field gel electrophoresis (PFGE) Southern blots. A precise organization of the 700-kb segment of DNA between G18 and BAT1 can now be proposed, with more than 30 genes mapped to it. Comparison of this region with homologous regions in human and mouse showed only minor differences. The biggest difference was observed in the CYP21/C4 locus with only one CYP21 gene and one C4 gene found, whereas in human and mouse these genes are duplicated. These results show the class III region is very well conserved between pig, human, and mouse, in contrast with the class I and class II regions, which seem more prone to rearrangements.

Animals↗
PubMed1996

Swine cytosolic malic enzyme: cDNA cloning, sequencing, and localization.

A highly significant genetic association has been found between some alleles of the swine Major Histocompatibility Complex SLA (Swine Leukocyte Antigen genetic complex) and the cytosolic malic enzymatic activity level in muscles. The aim of this study was to find out whether this genetic association was due to a close linkage of the SLA region and the gene coding for the enzyme. Since no swine cytosolic malic enzyme sequence (ME1) was available, we isolated several overlapping fragments that spanned the almost entire malic enzyme transcript both by screening of a swine cDNA library and by RT-PCR. The results indicated the existence of two transcripts of 2. 0 and 3.1 kb, which probably correspond to two alternative forms of one gene. The sequence of the transcript was highly similar to the other published mammalian cytosolic NADP+-dependent malic enzyme cDNA, especially within the four functional domains. Two major bands at 3.7 and 2.4 kb were detected on Northern blots containing the RNA from 25 tissues from fetuses and adult pigs. A high expression level was found in the adrenal gland, muscle, liver, and peripheral nerves. The analysis of malic enzyme RFLPs in five SLA informative families revealed an independent segregation of the ME1 gene from the SLA region. In situ hybridization results localized the cytosolic malic enzyme on the swine Chromosome (Chr) 1p1.2, except that the association between SLA and the malic enzyme activity level was due to a physical genetic linkage. Thus, the mechanisms underlying this association remain to be elucidated.

Amino Acid Sequence↗
PubMed1996

An experimental model for testing von Willebrand factor function: successful SLA-matched crossed bone marrow transplantations between normal and von Willebrand pigs.

To assess the relative in vivo roles of von Willebrand factor (vWF) of different origins, we performed crossed bone marrow transplantations (BMTs) among normal pigs and pigs with the von Willebrand disease(vWF). The two groups were fully compatible immunologically according to typing by swine leukocyte antigen (SLA). After total-body irradiation (8-10 Gy), all pigs received 0.5X10(9) to 10(10)/kg mononuclear bone marrow cells without any immunosuppression. The nadir of aplasia occurred between days 5 and 7 after irradiation (white blood cell [WBC] count 0.6X10(9)/L, platelet [Plt] count 76X10(9)/L. Three weeks after the graft, WBC and Plt counts had returned to normal levels. Animals were followed for at lease 50 days, during which no bone marrow rejection occurred; no evidence of graft-vs-host disease (GVHD) was observed. Each BMT was confirmed by karyotype analysis. In the six homozygous pigs with vWD grafted with normal marrow, platelet vWF antigen (vWFAg) and platelet vWF activity rose from <3 to 450 U/dl with a normal multimeric pattern; plasma vF increases slightly. No correction of bleeding time was observed. In the five normal pigs grafted with bone marrow form pigs with vWD, platelet vWFAg and platelet vWF activity decreased from >100 U/dl to undetectable levels; bleeding time and plasma vWFAg remained unchanged. A derivative of normal porcine plasma, a concentrate containing factor VIII and vWF, was infused into a homozygous vWD pig before and after BMT from a normal pig. Co correction of bleeding time was obtained, even though plasma nd platelet vWFAg levels were normal. W concluded that crossed BMT among SLA-identical pigs is a feasible model of studying the synthesis and the roles of vWF in hemostasis and thrombosis.

Animals↗