Random changes of amino acid residues with expected frequency by saturated point mutagenesis

The yeast transcriptional activator protein, Gcn4p from Saccharomyces cerevisiae binds to the specific sequence in the promoters of many amino acid biosynthetic genes for general control. A new random saturation mutagenesis method was developed to isolate Gcn4p derivatives with only one or two mutations in the DNA binding domain without using radioactive isotope. This will be used to identify the amino acids of Gcn4p involved in protein-protein interactions. Saturation mutagenesis in the DNA binding domain of Gcn4p was performed using spiked degenerate oligonucleotides containing randomized codon bases designed specifically for only one or two base changes in the mutagenized area. These oligonucleotides were synthesized to have two flanking restriction enzyme sites for cloning to the appropriate vector. The 3' ends were mutually primed after hybridization via the palindromic sequences of the restriction enzyme sites. These molecules were then converted to double stranded DNA upon treatment with DNA polymerase. Here, a library collection of 100,680 in an altered Gcn4p pool was generated by cloning a mixed-base oligonucleotide in the place of the sequence coding for the DNA binding domains. The quality of the library was examined by DNA sequencing and found to be in good agreement with the expected statistical values. Calculated mutation frequency was 66% of mutant nucleotide rate and actual sequencing data revealed 68% mutant nucleotide rates from the sequenced library. Thus, among 21 mutants, 16 had one point mutations and 5 had two point mutations. This approach appears to be an effective and general tool for creating proteins with one or two amino acid change(s) in their molecules.

Improved development of DNA-injected bovine embryos co-cultured with mouse embryonic fibroblast cells

The in vitro development of DNA-injected bovine zygotes, produced in vitro, was compared when cultured with or without mouse embryonic fibroblasts (MEF). The in vivo viability of the embryos produced in these in vitro culture systems was assessed by single or double transfer to recipients taken to term. For these experiments, in vitro fertilized oocytes were not injected (Experiment 1) or were injected with pBL1 gene (Experiment 2) and then cultured for 2 days in CR1aa medium supplemented with 3 mg/ml BSA at 38.5 degrees C in a humidified atmosphere of 5% CO(2) in air. Embryos that developed to the 4- to 8-cell stage at the end of this period were randomly assigned to the two cultured systems and cultured for a further 5 days in groups of 10 to 15 embryos in 0.75 ml medium. These two culture systems were CR1aa medium alone or co-culture with MEF in CR1aa medium supplemented with 10% fetal bovine serum (FBS). Every 48 h, 0.5 ml of the medium was replaced with fresh CR1aa medium and at Day 5 of culture, both media were supplemented by the addition of 5.56 mM glucose and 1x GMS-X supplement solutions. Results were assessed as morphological development of the embryos and data were analyzed by Chi-square test or Student's t-test. The development rate of in vitro fertilization (IVF)-derived embryos co-cultured with MEF (24.4%, 49/201) was significantly higher than those cultured alone (14.4%, 28/194; P<0.05) in Experiment 1. There was a similar difference between the treatments in the proportions of embryos which reached the hatching stage or hatched (10.9%, 22/201 vs. 4.1%, 8/194, respectively; P<0.05). DNA-injected embryos co-cultured with MEF (13.7%, 28/205) showed a higher developmental rate than that of the embryos cultured without MEF (6.7%, 13/193; P<0.05) in Experiment 2. Following the transfer to recipients of one or two DNA-injected blastocysts, the pregnancy rates for two culture systems were similar (MEF co-culture 27.4%, 23/84; CR1aa culture 24. 2%, 16/66). However, the numbers of calves born alive from these pregnancies were higher on the MEF co-culture group (82.6%, 19/23) than the CR1aa culture group (56.2%, 9/16). It was concluded that in vitro embryo development to the blastocyst stage and subsequent in vivo development to term of DNA-injected bovine embryos was improved in comparison to culture in CR1aa alone when the last 5 days of in vitro culture were in a MEF co-culture system.

Loss of TGF-beta signaling contributes to autoimmune pancreatitis

Recent observations suggest that immune response is involved in the development of pancreatitis. However, the exact pathogenesis underlying this immune-mediated response is still under debate. TGF-beta has been known to be an important regulating factor in maintaining immune homeostasis. To determine the role of TGF-beta in the initiation or progression of pancreatitis, TGF-beta signaling was inactivated in mouse pancreata by overexpressing a dominant-negative mutant form of TGF-beta type II receptor in the pancreas, under control of the pS2 mouse trefoil peptide promoter. Transgenic mice showed marked increases in MHC class II molecules and matrix metalloproteinase expression in pancreatic acinar cells. These mice also showed increased susceptibility to cerulein-induced pancreatitis. This pancreatitis was characterized by severe pancreatic edema, inflammatory cell infiltration, T- and B-cell hyperactivation, IgG-type autoantibodies against pancreatic acinar cells, and IgM-type autoantibodies against pancreatic ductal epithelial cells. Therefore, TGF-beta signaling seems to be essential either in maintaining the normal immune homeostasis and suppressing autoimmunity or in preserving the integrity of pancreatic acinar cells.

A disposable amperometric sensor screen printed on a nitrocellulose strip: a glucose biosensor employing lead oxide as an interference-removing agent

A new type of disposable amperometric sensor is devised by screen printing thick-film electrodes directly on a porous nitrocellulose (NC) strip. The chromatographic NC strip is then utilized to introduce various sample pretreatment layers. As a preliminary application, a glucose biosensor based on hydrogen peroxide detection is constructed by immobilizing glucose oxidase (GOx) on the NC electrode strip and by formulating a strong oxidation layer (i.e., PbO2) at the sample loading area, placed below the GOx reaction band. The screen-printed PbO2 paste serves as a sample pretreatment layer that removes interference by its strong oxidizing ability. Samples applied are carried chromatographically, via the PbO2 paste, to the GOx layer, and glucose is catalyzed to liberate hydrogen peroxide, which is then detected at the electrode surface. The proposed NC/PbO2 strip sensor is shown to be virtually insusceptible to interfering species such as acetaminophen and ascorbic and uric acids and to exhibit good performance, in terms of the sensor-to-sensor reproducibility (standard deviation, +/-0.026 - +/-0.086 microA), the sensitivity (slope, -0.183 microA/mM), and the linearity (correlation coefficient, 0.994 in the range of 0-10 mM).

Interleukin 8 expression regulates tumorigenicity and metastasis in human bladder cancer

Interleukin 8 (IL-8) is mitogenic and chemotactic for endothelial cells. Within a neoplasm, IL-8 is secreted by inflammatory and neoplastic cells. The highly tumorigenic and highly metastatic human transitional cell carcinoma (TCC) cell line 253J B-V overexpresses IL-8 relative to the nontumorigenic and nometastatic 253J-P cell line. To determine whether IL-8 expression regulates tumorigenicity and metastasis in human TCC, 253J B-V cells were transfected with the full-sequence antisense (AS) cDNA for IL-8, whereas 253J-P cells were transfected with the full-length IL-8 cDNA, and control cells for each were transfected with the neomycin resistance (Neo) gene. In vitro, sense-transfected 253J-P cells overexpressed IL-8-specific mRNA and protein, whereas both of these were markedly reduced in AS-IL-8-transfected 253J B-V cells relative to controls. Moreover, sense-transfected cells showed up-regulation in matrix metalloproteinase type 9 mRNA, collagenase activity, and increased invasiveness through Matrigel-coated filters, whereas these measures were lower in AS-transfected cells relative to controls. After implantation into the bladders of athymic nude mice, the sense-transfected 253J-P cells acquired increased tumorigenicity and metastasis, whereas the AS-transfected cells significantly inhibited tumorigenicity and metastases in the 253J B-V cell lines. This effect was accompanied by reduced IL-8 expression and microvessel density. These studies demonstrate that IL-8 expression enhances angiogenic activity through the induction of matrix metalloproteinase type 9 and subsequently regulates the tumorigenesis and production of spontaneous metastases of human TCC.

Molecular cloning and characterization of the mouse peroxiredoxin V gene

We have cloned two cDNA isoforms as well as genomic sequences of the mouse Prx V gene and characterized their molecular genetic features. Two isoforms of the mouse Prx V cDNA were identified from liver and testis. The testis-originated long transcripts had extra 1164-bp 5'-UTR sequences compared to the liver-originated short transcripts. Primer extension and sequence analyses revealed that the two isoforms were presumably transcribed at the same gene locus. The gene was composed of six exons spanning 3.2 kb. The short transcript was abundantly expressed in the kidney, liver, and heart of the adult mouse tissues and in the extra-membrane of the 10.5 dpc embryos. The long transcript of 1985 bp was abundantly detected in testis with trace amounts in other tissues. Interestingly, in testis and fetus, only mRNA expression of the long form was identified. However, the protein expression was not found in testis, implying that the long form could not properly direct the protein expression. The long Prx V cDNA has eight uORFs in the extra 5'-UTR, which proceed the major ORF. The inability of protein expression for the long-form cDNA in testis suggests that the uORFs might inhibit translation of the major ORF and thereby confer the tissue-specific regulation of the mouse Prx V gene.

Haploid loss of the tumor suppressor Smad4/Dpc4 initiates gastric polyposis and cancer in mice

The tumor suppressor SMAD4, also known as DPC4, deleted in pancreatic cancer, is a central mediator of TGF-beta signaling. It was previously shown that mice homozygous for a null mutation of Smad4 (Smad4-/-) died prior to gastrulation displaying impaired extraembryonic membrane formation and endoderm differentiation. Here we show that Smad4+/- mice began to develop polyposis in the fundus and antrum when they were over 6 - 12 months old, and in the duodenum and cecum in older animals at a lower frequency. With increasing age, polyps in the antrum show sequential changes from hyperplasia, to dysplasia, in-situ carcinoma, and finally invasion. These alterations are initiated by a dramatic expansion of the gastric epithelium where Smad4 is expressed. However, loss of the remaining Smad4 wild-type allele was detected only in later stages of tumor progression, suggesting that haploinsufficiency of Smad4 is sufficient for tumor initiation. Our data also showed that overexpression of TGF-beta1 and Cyclin D1 was associated with increased proliferation of gastric polyps and tumors. These studies demonstrate that Smad4 functions as a tumor suppressor in the gastrointestinal tract and also provide a valuable model for screening factors that promote or prevent gastric tumorigenesis.

Activation of NF-kappaB determines the sensitivity of human colon cancer cells to TNFalpha-induced apoptosis

Tumor necrosis factor alpha (TNFalpha) generates a potent cytotoxic effect, however many cancer cells are resistant to TNFalpha-mediated killing and the cause of the differential sensitivity remains to be elucidated. In this study, we demonstrated that TNFalpha induced cell death in four different human colon cancer cell lines. The degree of cytotoxic effect was different in each cell line, in that HCT-15 was relatively sensitive, while DLD-1, HT-29 and WiDr were relatively resistant. TNFalpha induced apoptotic changes such as morphological changes, DNA fragmentation and activation of caspase-3 in HCT-15, but to a lesser degree in the others. Transcriptional expression of TNFR1(p55), as well as that of FLICE, Fas, FADD, DR3, FAF, TRADD, and RIP was similar in these cell lines, indicating that the susceptibility to TNFalpha-induced apoptosis may not be determined by the constitutive expression level of these factors. Interestingly, the cytotoxic effect of TNFalpha was well correlated with the DNA binding activity of NF-kappaB in the colon cancer cell lines. Further, the overexpression of a non-phosphorylated mutant form of IkappaBalpha enhanced the cytotoxicity of TNFalpha in the resistant cell line, DLD-1, indicating that NF-kappaB activity may determine the sensitivity of colon cancer cells to TNFalpha-induced apoptosis. Thus, our results indicate that modulation of NF-kappaB activity may provide a useful tool to sensitize colon cancer cells to TNFalpha treatment.

Comparison of 1- and 2-incision posterior cruciate ligament reconstructions

This study compared the results of the 1-incision technique and the conventional 2- incision technique for the arthroscopic treatment of the posterior cruciate ligament (PCL) injury. The 2-incision technique was performed in 10 patients (group I) and the 1-incision technique in 45 patients (group II). The average duration of follow-up was 45 months in group I and 36 months in group II. Bone-patellar tendon-bone (BTB) autografts were used for all patients in group I. In group II, 34 BTB autografts and 11 BTB allografts were used. Postoperative Lysholm mean values were 90.0 in group I and 90.6 in group II. HSS mean values were 87.7 in group I and 92.6 in group II (P = .037). The Tegner activity level scales were 6.4 in group I and 6.5 in group II. The average side-to-side difference of the corrected posterior translation measured by the KT-2000 arthrometer were 2.10 mm in group I and 2.38 mm in group II. There were no statistically significant differences between the 2 groups in postoperative mean values except HSS scores. The arthroscopic PCL reconstruction using the 1-incision technique showed good results comparable with the conventional 2-incision technique. This technique needs no another incision or dissection over the medial femoral condyle.

Osseous metaplasia with functioning bone marrow in hydroxyapatite orbital implants

BACKGROUND

Bone formation within the hydroxyapatite implant has been reported in explanted spheres in humans. Bone-specific differentiation was observed to occur earlier in the pores of spherical hydroxyapatite implants enhanced with osteogenin within the rabbit socket. We observed previously unreported bone marrow formation in a coralline hydroxyapatite implant placed into the rabbit orbit after evisceration.

METHODS

One eye of each of 10 New Zealand white rabbits weighing between 2 and 3 kg was eviscerated and implanted with hydroxyapatite spheres. The explanted hydroxyapatite spheres 20 weeks after surgery were examined under the microscope.

RESULTS

Histopathologic examination of the excised implants showed the presence of trabeculae of mature bone with fatty marrow and hematopoietic elements. Scattered throughout the fatty tissue were bone marrow elements consisting of precursors of the granulocytic and erythroid series and also megakaryocytes.

CONCLUSION

The osseous metaplasia with functioning bone marrow was incidentally observed in the coralline hydroxyapatite implant without the addition of any osteogenesis-inducing agents.

Novel de novo nonsense mutation of MECP2 in a patient with Rett syndrome

Because of the recent identification of several mutations of methyl-CpG-binding protein 2 (MECP2) in patients with Rett syndrome (RTT), a patient with suspected RTT from an autism clinic was screened for mutations. She was found to have a novel heterozygous nonsense mutation, 129C>T (Q19X), which leads to the most severely truncated MECP2 protein reported to date. Sequencing of parental DNA revealed the mutation was de novo. The patient was not affected with microcephaly or hyperventilation, but had other features of Rett syndrome including severe mental retardation and symptoms of autistic disorder. Moderately skewed X-chromosome inactivation (XCI) may have contributed to her relatively mild phenotype.

Inhibition of apamin-sensitive K+ current by hypoxia in adult rat adrenal chromaffin cells

The effect of hypoxia on small-conductance Ca(2+)-activated K+ current was investigated in a study of adult rat adrenomedullary chromaffin cells (AMCs), which were maintained in short-term culture. The nystatin-perforated, whole-cell patchclamp technique was used to study the effect of hypoxia with minimum perturbation of the intracellular milieu. Under voltage-clamp conditions, acute hypoxia (P(O2) approximately equal to 25 mmHg) suppressed the whole-cell outward currents of more than half the AMCs (24/46). This suppression was eliminated after application of apamin (400 nM), a selective inhibitor of small-conductance Ca(2+)-activated K+ current (I(SK)(Ca)) (n=5), suggesting that an apamin-sensitive component of whole-cell currents is suppressed during hypoxia. In contrast to I(SK)(Ca), Ca2+ current (I(Ca)) (n=10) was not affected by hypoxia. Finally, under current-clamp conditions, hypoxia reversibly depolarized the resting membrane potential of adult AMCs (34/40). Apamin, however, eliminated the hypoxia-induced depolarization (400 nM) (7/8), suggesting that hypoxic depolarization is related to the suppression of I(SK(Ca). From the above results, we conclude that adult AMCs are sensitive to hypoxia, and that I(SK)(Ca) contributes to the hypoxia-induced suppression of whole-cell outward current and depolarization of the resting membrane potential in adult AMCs.

EWS-FLI1, EWS-ERG, and EWS-ETV1 oncoproteins of Ewing tumor family all suppress transcription of transforming growth factor beta type II receptor gene

Ewing sarcoma-specific chromosomal translocations fuse the EWS gene to a subset of ets transcription factor family members, most commonly the FLI1 gene and less frequently ERG, ETV1, E1A-F, or FEV. These fusion proteins are thought to act as aberrant transcription factors that bind DNA through their ets DNA binding domain. Recently, we have shown (K-B. Hahm et al., Nat. Genet., 23: 222-227, 1999) that the transforming growth factor beta (TGF-beta) type II receptor (TGF-beta RII), a putative tumor suppressor gene, is a target of the EWS-FLI1 fusion protein. Here, we also examined effects of EWS-ETV1 and EWS-ERG on expression of the TGF-beta RII gene. We show that relative to the control, NIH-3T3 cell lines stably transfected with the EWS-FLI1, EWS-ERG, or EWS-ETV1 gene fusion express reduced levels of TGF-beta RII mRNA and protein, and that these cell lines have reduced TGF-beta sensitivity. Cotransfection of these fusion genes and the TGF-beta RII promoter suppresses TGF-beta RII promoter activity and also FLI1-, ERG-, or ETV1-induced promoter activity. These results indicate that transcriptional repression of TGF-beta RII is an important target of the EWS-FLI1, EWS-ERG, or EWS-ETV1 oncogene, and that EWS-ets fusion proteins may function as dominant negative forms of ets transcription factors.

Antiproliferative effects of retinoic acid/interferon in cervical carcinoma cell lines: cooperative growth suppression of IRF-1 and p53

Retinoids and interferons have been implicated in the growth regulation of cervical cancer cells. However, the molecular mechanisms are not fully defined. To analyze detailed mechanisms, HPV-positive (HeLa, CaSki), HPV-negative (C33A, HT-3) and non-cervical Cos-1 cell lines were treated with I microM all-trans-retinoic acid (RA) and/or 10 ng/ml interferon-gamma (IFN-gamma). The growth of RA-treated HeLa cells was less effectively suppressed than that of IFN-gamma-treated ones. A combination of RA and IFN-gamma leads to an additive antiproliferative effect on the cell growth. CaSki cell growth was also inhibited by IFN-gamma but was little stimulated by RA treatment, and the IFN effect was attenuated when IFN-gamma was combined with RA. HPV-negative C33A and HT-3 cells, which are defective in p53 and Rb, and Cos- 1 cells were weakly or not responsive to all combined treatments. The molecular mechanism underlying the differential effects of RA/IFN on HeLa and C33A cells was investigated. Combined RA/IFN-gamma treatment caused a marked increase in the level of IFN regulatory factor-1 (IRF-1) in HeLa, whereas no induction of IRF-1 was observed in C33A, consistent with the findings that IFN signaling is functional in HeLa but is defective in C33A cells. The increase of p53 in HeLa cells might account for the down-regulation of HPV-18 E6 gene expression by RA/IFN-gamma. Furthermore, RA/IFN-gamma treatment resulted in the concurrent induction of p21WAF1 CDK inhibitor and dephosphorylation of Rb protein. Transient co-expression of IRF-1 and p53 led to the cooperative activation of the p21WAF1 promoter. Our results indicate that 2 transcription factors, increased in response to RA/IFN-gamma, cooperate functionally to regulate the cell cycle through the activation of a common p21WAF1 gene in HeLa cells.

Differentiation of Salmonella enterica serotype gallinarum biotype pullorum from biotype gallinarum by analysis of phase 1 flagellin C gene (fliC)

Salmonella enterica serotype gallinarum biotype gallinarum and biotype pullorum are non-motile and pathogenic avian strains. Biotype gallinarum causes fowl typhoid and biotype pullorum is the cause of pullorum disease in chickens. The two biotypes could be differentiated based on biochemical characteristics. However, conventional culture and biochemical assays are time-consuming, laborious and need sterile laboratory practices. Although the two biotypes, gallinarum and pullorum are non-motile, they possess the phase 1 flagellin C gene. The variable regions of the flagellin C gene from 41 biotype pullorum and 52 biotype gallinarum were amplified by colony-PCR and analyzed by single strand conformational polymorphism (SSCP) method. Differences in SSCP electrophoretic patterns were confirmed by nucleotide sequencing. In addition, PCR-RFLP with Hinp1I was also successfully applied to differentiate the two biotypes. These results suggested that the variable regions of fliC could be used as a genetic marker to differentiate biotype gallinarum from biotype pullorum.

Semiinvasive pulmonary aspergillosis: CT and pathologic findings in six patients

OBJECTIVE

We describe the chest CT and pathologic findings of semiinvasive pulmonary aspergillosis in six patients.

CONCLUSION

Semiinvasive pulmonary aspergillosis should be considered in the mildly immunocompromised patient with CT findings that reveal persistent parenchymal abnormalities. Patterns include consolidation and mass.

Differential effects of retinoic acid on growth and apoptosis in human colon cancer cell lines associated with the induction of retinoic acid receptor beta

Retinoids are well known as potential chemopreventive and chemotherapeutic agents against a variety of human cancers. Here, we report that retinoic acid (RA) induced differential growth inhibition in human colon cancer cell lines: while DLD-1, HT-29, and WiDr were relatively resistant, HCT-15 and Colo201 were relatively sensitive. All-trans-retinoic acid caused morphological and biochemical changes such as membrane shrinkage, chromatin condensation, and DNA cleavage, which are typical features of cells undergoing apoptosis in sensitive cell lines. Although retinoic acid receptor (RAR)alpha, beta, gamma and retinoid X receptor alpha were expressed in all cell lines examined, a significant induction of RARbeta by all-trans-RA was observed only in sensitive cell lines, suggesting important roles of RARbeta in RA sensitivity. When a vector containing the RARbeta gene was introduced into a relatively resistant cell line, DLD-1, the cells acquired RA sensitivity. Further, we found that the RARbeta transfectants of DLD-1 expressed an enhanced level of c-Myc and Bax proteins, which may result in the increased susceptibility of the cells to all-trans-RA-induced apoptosis. In summary, our data demonstrated that RA induced growth inhibition and apoptosis in human colon cancer cells and that the induction of RAR3 may mediate the retinoid action.

Increase in bacterial community diversity in subsurface aquifers receiving livestock wastewater input

Despite intensive studies of microbial-community diversity, the questions of which kinds of microbial populations are associated with changes in community diversity have not yet been fully solved by molecular approaches. In this study, to investigate the impact of livestock wastewater on changes in the bacterial communities in groundwater, bacterial communities in subsurface aquifers were analyzed by characterizing their 16S rDNA sequences. The similarity coefficients of restriction fragment length polymorphism (RFLP) patterns of the cloned 16S ribosomal DNAs showed that the bacterial communities in livestock wastewater samples were more closely related to those in contaminated aquifer samples. In addition, calculations of community diversity clearly showed that bacterial communities in the livestock wastewater and the contaminated aquifer were much more diverse than those in the uncontaminated aquifer. Thus, the increase in bacterial-community diversity in the contaminated aquifer was assumed to be due to the infiltration of livestock wastewater, containing high concentrations of diverse microbial flora, into the aquifer. Phylogenetic analysis of the sequences from a subset of the RFLP patterns showed that the Cytophaga-Flexibacter-Bacteroides and low-G+C gram-positive groups originating from livestock wastewater were responsible for the change in the bacterial community in groundwater. This was evidenced by the occurrence of rumen-related sequences not only in the livestock wastewater samples but also in the contaminated-groundwater samples. Rumen-related sequences, therefore, can be used as indicator sequences for fecal contamination of groundwater, particularly from livestock.

Molecular mechanisms of inactivation of TGF-beta receptors during carcinogenesis

Signals from the TGF-betas are mediated by the TGF-beta receptors and their substrates, the Smad proteins. Inactivation of either of the two transmembrane serine/threonine kinases called the TGF-beta type I and type II receptors is now known to underlie a wide variety of human pathologies including, especially carcinogenesis. Numerous studies have now demonstrated that the TGF-beta receptor complex and its downstream signaling intermediates constitute a tumor suppressor pathway. We review here a specific pathway of mutational inactivation of the TGF-beta type II receptor resulting from microsatellite instability and demonstrate that, by contrast, the most common mechanism of loss of expression of the TGF-beta type II receptor involves transcriptional repression. This provides a new target for therapeutic intervention.

Characterization of Borrelia burgdorferi strains isolated from Korea by 16S rDNA sequence analysis and PCR-RFLP analysis of rrf (5S)-rrl (23S) intergenic spacer amplicons

Haenam strains of Borrelia burgdorferi, which had been isolated from Ixodes granulatus and Apodemus agrarius in Haenam, Korea, were characterized by PCR-RFLP analysis of rrf (5S)-rrl (23S) intergenic spacer amplicons and by sequence analysis of the 16S rRNA gene (rDNA). The Msel and Dral restriction patterns of the 5S-23S intergenic spacer amplicons of Haenam strains differed from those of other B. burgdorferi sensu lato strains. Furthermore, in the phylogenetic tree based on the 16S rDNA sequences, Haenam strains formed a distinctive cluster, clearly separated from the other members of B. burgdorferi sensu lato. These results suggest that, apart from Borrelia garinii and Borrelia afzelii, other genotypes of B. burgdorferi sensu lato exist in Korea and the Haenam strain is a newly identified one.

Mechanism of reduced GFR in rabbits with ischemic acute renal failure

A reduction in glomerular filtration rate (GFR) is a primary characteristic of ischemic acute renal failure. The present study was undertaken to examine the roles of angiotensin II, tubuloglomerular-feedback (TGF) mechanism, and tubular obstruction for the GFR reduction in the post-ischemic kidney. Renal ischemia was induced by occlusion of the bilateral renal arteries for 60 min, and renal function was examined at 2 and 24 h after the onset of reflow. After the end of 2-h reflow, the GFR was not significantly changed, but the urine flow increased significantly. On the other hand, at the end of 24-h reflow, the GFR and urine flow decreased markedly along with increased filtration fraction. The renal blood flow significantly decreased at 24 h, but not 2 h, after reflow, which was accompanied by increased total renal vascular resistance. Furosemide infusion (1 mg/min/kg) after 24 h of reflow prevented the reduction in GFR and filtration fraction without no changes in renal blood flow and total renal vascular resistance. Pretreatment of enalapril and losartan did not prevent the reduction in GFR, indicating that angiotensin II was not involved. In morphological examinations, tubular obstruction was seen in the proximal and distal tubules of kidneys both at 2 and 24 h after the onset of reflow. In two rabbits subjected to 48 h of reflow, the tubular obstruction was not observed, despite GFR remained depressed. These results suggest that the late reduction in GFR in postischemic kidneys is not mediated by angiotensin II, but is mediated, at least in part, by the TGF mechanism. The tubular obstruction may be not prerequisite for the GFR reduction in rabbits.

Diversity of the p70 killer cell inhibitory receptor (KIR3DL) family members in a single individual

NK cells and some T cells express members of a multigenic family of killer cell inhibitory receptors (KIRs) including p70 KIR (KIR3DL) and p58 KIR (KIR2DL) family that recognize polymorphic class I MHC molecules on target cells and transmit an inhibitory signal to prevent killer cell-mediated cytoxicity. The cDNA sequences of p70 KIR family members reported so far suggest that the p70 KIR gene consists of a multigene complex and that each gene may exhibit certain degrees of polymorphism. However, it is not clear how diverse the repertoire of the p70 KIR family is, particularly in a single individual. To address this question in more detail and to determine some indication as to the origin of the diversity, we cloned p70 KIR cDNAs from a single individual. We identified nine new KIRs that are different from the previously reported ones. A comparison of the amino acid sequences with published sequences of p70 KIRs showed that two clones belonged to the KIR3DL1 family, five clones belonged to the KIR3DL2 family, one clone belonged to the KIR2DL4 family, and one clone appeared to be an alternatively spliced form of p70 KIR. These results suggested that the repertoire of p70 KIR family members in a single individual is highly diverse. It is not clear how the diverse receptors are generated in a single individual, but a comparison of amino acid sequences of p70 KIR family members suggested that some of them may be encoded by distinct genes or their alleles, while others may be generated by a recombination mechanism and/or an alternative splicing mechanism at the maturation of the mRNA transcripts.

Cu(II) Sorption Mechanism on Montmorillonite: An Electron Paramagnetic Resonance Study

The mechanism of Cu(II) sorption on montmorillonite was studied with electron paramagnetic resonance (EPR) spectroscopy. The major sorbed species were successfully identified by EPR spectroscopy as they showed distinct signals due to their strength of binding and local structure. The EPR results together with macroscopic sorption data show that the sorption involves at least three different mechanisms. The dominant sorption mechanism changed with pH and Na(+) content in solution. In the acidic pH range, the sorption is independent of pH but is dependent on Na(+) concentration. Like free copper ions, the sorbed Cu(II) shows an isotropic absorption line. It is thought that the Cu(II) is ion-exchanged in the interlayer site and is capable of free tumbling motion despite electrostatic binding force. In the near neutral pH range, the sorption is strongly pH dependent and the sorbed Cu(II) shows no EPR signal. It is interpreted that the Cu(II) is sorbed by a surface complexation mechanism to form an inner-sphere surface complex. The EPR spectrum with a dipolar splitting pattern means that the dimeric Cu(II) surface species is the dominant sorbed species in the basic pH region where the Cu-Cu internuclear distance of the dimer is estimated to be approximately 3.3 Å. Copyright 2000 Academic Press.

Morphologic change of the internal elastic lamina in Buerger's disease

Morphologic features and pathogenesis of arterial changes occurring in Buerger's disease (thromboangiitis obliterans) are still controversial. This study describes histopathologic features of medium sized arteries from patients with Buerger's disease, particularly of the internal elastic lamina in relation to the immunologic mechanism of the injury. Seventeen segments of occluded arteries (femoral or popliteal arteries) from 17 patients with Buerger's disease were analyzed by histopathological and immunohistochemical methods. The most characteristic features were total luminal obliteration, together with a varying degree of recanalization and deposition of hemosiderin pigments. Detailed analysis, however, showed marked undulation and multiplication of the internal elastic lamina (100%) associated with basophilic degeneration and delicate linear calcification (47%). Lymphocytic infiltration along the internal elastic lamina was seen in 71% and was associated with localized edema. Lymphocytes along the lamina were consistently positive for T cell marker. Mild to moderate fibrosis was present at the media in 24%. Adventitial changes included mild, nonspecific and irregular fibrosis seen in 53%. Immunologic injury to the internal elastic lamina associated with T-lymphocytic infiltration might be the initial morphogenetic mechanism of the thrombotic occlusion and organization of medium-sized arteries in Buerger's disease.