Distortion product otoacoustic emissions in diabetics with normal hearing

In 18 diabetic patients with normal hearing, distortion product otoacoustic emissions (DPOAEs) were measured. DPOAEs' amplitude and latency were analysed and compared with the data obtained from non-diabetic controls. The mean amplitude and latency were lower in diabetics than in controls. These results suggested that diabetes mellitus may induce the functional alteration of outer hair cells even in the normal hearing group. Further studies should be performed to evaluate the predictability of DPOAEs in hearing loss of the diabetic patient.

Recurrent pyogenic cholangitis: comparison between MR cholangiography and direct cholangiography

PURPOSE

To compare the accuracy of magnetic resonance (MR) cholangiography with that of direct cholangiography for the evaluation of recurrent pyogenic cholangitis.

MATERIALS AND METHODS

Twenty-four patients with recurrent pyogenic cholangitis underwent MR cholangiography before surgery, and 18 of these 24 also underwent direct cholangiography. Two reviewers evaluated MR cholangiograms and direct cholangiograms and focused on identifying intrahepatic ductal dilatation, stricture, and calculi, as well as coexistent parenchymal abnormalities, on the basis of the classification of the internal lobes and segments of the liver. These observations were compared with surgical findings.

RESULTS

According to examination results in the surgical specimens, 24 patients had 46 segmental abnormalities. MR cholangiography depicted all 46 (100%) segments with ductal dilatation, 22 (96%) of 23 segments with focal ductal stricture, and 43 (98%) of 44 segments with ductal calculi. Eighteen patients who underwent direct cholangiography had 32 segmental abnormalities according to examination results in the surgical specimens. Direct cholangiography depicted 15 (47%) of 32 segments with ductal dilatation, eight (44%) of 18 segments with focal ductal stricture, and 14 (45%) of 31 segments with ductal calculi.

CONCLUSION

MR cholangiography is superior to direct cholangiography for accurate topographic evaluation of recurrent pyogenic cholangitis because it is able to depict all of the biliary tree, despite obstruction or stenosis.

Generation of protein lineages with new sequence spaces by functional salvage screen

A variety of different methods to generate diverse proteins, including random mutagenesis and recombination, are currently available and most of them accumulate the mutations on the target gene of a protein, whose sequence space remains unchanged. On the other hand, a pool of diverse genes, which is generated by random insertions, deletions and exchange of the homologous domains with different lengths in the target gene, would present the protein lineages resulting in new fitness landscapes. Here we report a method to generate a pool of protein variants with different sequence spaces by employing green fluorescent protein (GFP) as a model protein. This process, designated functional salvage screen (FSS), comprises the following procedures: a defective GFP template expressing no fluorescence is first constructed by genetically disrupting a predetermined region(s) of the protein and a library of GFP variants is generated from the defective template by incorporating the randomly fragmented genomic DNA from Escherichia coli into the defined region(s) of the target gene, followed by screening of the functionally salvaged, fluorescence-emitting GFPs. Two approaches, sequence-directed and PCR-coupled methods, were attempted to generate the library of GFP variants with new sequences derived from the genomic segments of E.coli. The functionally salvaged GFPs were selected and analyzed in terms of the sequence space and functional properties. The results demonstrate that the functional salvage process not only can be a simple and effective method to create protein lineages with new sequence spaces, but also can be useful in elucidating the involvement of a specific region(s) or domain(s) in the structure and function of protein.

Resistance to xenobiotic-induced autoimmunity maps to chromosome 1

Although evidence indicates that environmental factors play a major role in precipitating systemic autoimmunity in genetically susceptible individuals, little is known about the mechanisms involved. Certain heavy metals, such as mercury, are potent environmental immunostimulants that produce a number of immunopathologic sequelae, including lymphoproliferation, hypergammaglobulinemia, and overt systemic autoimmunity. Predisposition to such metal-induced immunopathology has been shown to be influenced by both MHC and non-MHC genes, as well as susceptibility to spontaneous lupus, in mice and other experimental animals. Among the various mouse strains examined to date, the DBA/2 appears to uniquely lack susceptibility to mercury-induced autoimmunity (HgIA), despite expressing a susceptible H-2 haplotype (H-2d). To define the genetic basis for this trait, two genome-wide scans were conducted using F2 intercrosses of the DBA/2 strain with either the SJL or NZB strains, both of which are highly susceptible to HgIA. A single major quantitative trait locus on chromosome 1, designated Hmr1, was shown to be common to both crosses and encompassed a region containing several lupus susceptibility loci. Hmr1 was linked to glomerular immune complex deposits and not autoantibody production, suggesting that DBA/2 resistance to HgIA may primarily involve the later stages of disease pathogenesis. Identification and characterization of susceptibility/resistance genes and mechanisms relevant to the immunopathogenesis of mercury-induced autoimmunity should provide important insights into the pathogenesis of autoimmunity and may reveal novel targets for intervention.

A conditional replication-competent adenoviral vector, Ad-OC-E1a, to cotarget prostate cancer and bone stroma in an experimental model of androgen-independent prostate cancer bone metastasis

Prostate cancer has a high propensity to metastasize to bone, which often resists hormone, radiation, and chemotherapies. Because of the reciprocal nature of the prostate cancer and bone stroma interaction, we designed a cotargeting strategy using a conditional replication-competent adenovirus to target the growth of tumor cells and their associated osteoblasts. The recombinant Ad-OC-E1a was constructed using a noncollagenous bone matrix protein osteocalcin (OC) promoter to drive the viral early E1a gene with restricted replication in cells that express OC transcriptional activity. Unlike Ad-PSE-E1a, Ad-OC-E1a was highly efficient in inhibiting the growth of PSA-producing (LNCaP, C4-2, and ARCaP) and nonproducing (PC-3 and DU145) human prostate cancer cell lines. This virus was also found to effectively inhibit the growth of human osteoblasts and human prostate stromal cells in vitro. Athymic mice bearing s.c. androgen receptor-negative and PSA-negative PC-3 xenografts responded to a single intratumoral administration of 2 x 10(9) plaque-forming unit(s) of Ad-OC-E1a. In SCID/bg mice, intraosseous growth of androgen receptor-positive and PSA-producing C4-2 xenografts responded markedly to i.v. administrations of a single dose of Ad-OC-E1a. One hundred percent of the treated mice responded to this systemic Ad-OC-E1a therapy with a decline of serum PSA to an undetectable level, and 80% of the mice with PSA rebound responded to the second dose of systemic Ad-OC-E1a. Forty percent of the mice were found to be cured by systemic Ad-OC-E1a without subsequent PSA rebound or tumor cells found in the skeleton. This cotargeting strategy shows a broader spectrum and appears to be more effective than systemic Ad-PSE-E1a in preclinical models of human prostate cancer skeletal metastasis.

DNA ligase I and proliferating cell nuclear antigen form a functional complex

DNA ligase I is responsible for joining Okazaki fragments during DNA replication. An additional proposed role for DNA ligase I is sealing nicks generated during excision repair. Previous studies have shown that there is a physical interaction between DNA ligase I and proliferating cell nuclear antigen (PCNA), another important component of DNA replication and repair. The results shown here indicate that human PCNA enhances the reaction rate of human DNA ligase I up to 5-fold. The stimulation is specific to DNA ligase I because T4 DNA ligase is not affected. Electrophoretic mobility shift assays indicate that PCNA improves the binding of DNA ligase I to the ligation site. Increasing the DNA ligase I concentration leads to a reduction in PCNA stimulation, consistent with PCNA-directed improvement of DNA ligase I binding to its DNA substrate. Two experiments show that PCNA is required to encircle duplex DNA to enhance DNA ligase I activity. Biotin-streptavidin conjugations at the ends of a linear substrate inhibit PCNA stimulation. PCNA cannot enhance ligation on a circular substrate without the addition of replication factor C, which is the protein responsible for loading PCNA onto duplex DNA. These results show that PCNA is responsible for the stable association of DNA ligase I to nicked duplex DNA.

The factors of child physical abuse in Korean immigrant families

OBJECTIVE

This study explores Korean immigrant mothers' attitudes toward child physical abuse based on an ecological perspective.

METHOD

One hundred and forty-four Korean immigrant mothers who came to the US after age 16 and have at least one child under 18 years old participated in this study. Data were collected using instruments translated in Korean that measure mothers' attitudes toward child physical abuse in four areas: degree of agreement with physical abuse, conflict tactics, belief in the use of physical punishment, and perceptions regarding physical abuse.

RESULTS

This study found that the following variables affect Korean immigrant mothers' attitudes toward child physical abuse at ecological levels of the environment: amount of time spent with children, experience of corporal punishment as a child, children's gender and age, family acculturation conflicts, mothers' age, and length of time in US at the micro level; involvement in their children's school and involvement in social organizations at the meso level; level of education and reported stress of immigrant life at the exo level; value of children in Korean culture, familiarity with Child Protective Services (CPS), perceived discrimination, and value of corporal punishment at the macro level.

CONCLUSIONS

This study suggests the importance of cultural sensitivity in social work practice when working with Korean immigrants. It also implies that intervention and prevention efforts of child abuse should be targeted at more than one level of the environment.

Effects of bicarbonate/lactate solution on peritoneal advanced glycosylation end-product accumulation

Advanced glycosylation end-products (AGEs) are associated with diabetic complications and peritoneal damage after long-term peritoneal dialysis (PD) with high glucose dialysis solutions. Glucose degradation products (GDPs) derived during heat sterilization of high glucose dialysis solutions are thought to accelerate AGE formation. A new technique of separating glucose from electrolytes has yielded markedly lower GDP levels and permitted the use of dialysis solutions containing the physiologic buffer bicarbonate. Formation of AGEs in vitro with this new solution is significantly lower compared with formation of AGEs with conventional solutions. The purpose of the present study was to investigate the effect of long-term intraperitoneal use of new, neutral dialysis solution (B/L) containing bicarbonate (25 mmol/L) and lactate (15 mmol/L) on peritoneal AGE accumulation and permeability. Normal male Sprague-Dawley rats were used. Twice daily for 12 weeks, 30 mL of new solution (B/L) or conventional solution [Lac (lactate 40 mmol/L)] was injected into the peritoneal cavity of the test rats. As a control, rats that were not injected were kept for 12 weeks in the same manner as the test rats. After 12 weeks, a 2-hour peritoneal equilibration test (PET) was performed in the test rats. After the PET, the parietal peritoneum and liver were obtained for evaluation of peritoneal morphology and for immunohistochemistry for AGE. Intensity of AGE staining was semi-quantitatively graded from 0 to 3. The omentum was also obtained and immediately frozen for analysis of pentosidine content by high-performance liquid chromatography. Compared with findings in the control group, hematoxylin and eosin staining of the parietal peritoneum and liver samples revealed partial denudation of mesothelial cells in the Lac group; denudation was not remarkable in the B/L group. The B/L solution showed significantly less AGE staining in the peritoneal cavity compared to conventional solution. However, B/L solution failed to lower pentosidine levels. Intraperitoneal volume and the ratio of dialysate glucose at 2 hours to dialysate glucose at instillation (D2/D0 glucose) were significantly lower and the ratio of dialysate urea to plasma urea at 2 hours (D2/P2 urea) was significantly higher in the Lac and B/L groups than in the control group. Intraperitoneal volume was significantly higher in the B/L group than in the Lac group; D2/D glucose and D2P2 urea did not differ between the two groups. In conclusion, peritoneal ultrafiltration decreased after long-term PD. The B/L solution showed a small but statistically significant protective effect against decreasing ultrafiltration as compared with Lac solution. The B/L solution attenuated peritoneal AGE accumulation compared with conventional solution, but did not affect peritoneal pentosidine levels. These findings indicate that biochemical kinetics of various AGE peptides are not unique, but multivalent.

Comparison between posterolateral fusion with pedicle screw fixation and anterior interbody fusion with pedicle screw fixation in adult spondylolytic spondylolisthesis

There have been many reports regarding various operative methods for spondylolytic spondylolisthesis. However, there have been no reports regarding the comparison between posterolateral fusion (PLF) with pedicle screw fixation (PSF) and anterior lumbar interbody fusion (ALIF) with PSF. The purpose of the current study was to compare the clinical outcomes of PLF with PSF and ALIF with PSF, and to help in the selection of treatment options. Fifty-six patients with spondylolytic spondylolisthesis who underwent PLF with PSF (group 1, 35 patients) or who underwent ALIF with PSF (group 2, 21 patients) were studied. Minimum follow-up was 2 years. Demographic variables and disease state were similar for the two groups. We studied operating time, amount of blood loss, duration of hospital stay, clinical outcomes, complications, time at which fusion was complete, fusion rate, and radiological measurements. There were no significant differences between the two groups in terms of the amount of blood loss, duration of hospital stay, back pain, radiating pain, fusion rate, or complication rate. However, in group 2, the operation time and the time at which fusion became complete was longer, and in group 1 there was significant radiological reduction loss. In conclusion, PLF with PSF was just as effective as ALIF with PSF in terms of clinical outcomes, but ALIF with PSF was superior to PLF with PSF in terms of the prevention of reduction loss. Anterior support would be helpful for preventing reduction loss in cases of spondylolytic spondylolisthesis of the lumbar spine.

Primary humoral immune responses to formalin inactivated hemorrhagic fever with renal syndrome vaccine (Hantavax): consideration of active immunization in South Korea

The efficacy of a formalin-inactivated hemorrhagic fever with renal syndrome (HFRS) vaccine and the effectiveness of a related vaccination program have not been previously evaluated. We measured the primary immune responses to Hantavax by plaque reduction neutralizing antibody test (PRNT), hemagglutination inhibition test (HAI), ELISA and high density particle agglutination test (HDPA) in order to confirm a possible biological efficacy through independent substantiation of experimental results and to compare the results with previous studies. Following two doses of primary vaccination, the seroconversion rate of PRNT and HAI antibody was 33.3% (10/30) [95% C.I. 17.3-52.5%] and 26.7% (8/30) [95% C.I. 12.3-45.9%], respectively. The correlation between PRNT and HAI antibody showed a statistical significance (r=0.58, p<0.01). The seroconversion rate of HDPA and ELISA were both 76.7% (23/30) [95% C.I. 57.7-90.1%], which correlated well with each other (r=0.58, p<0.01). In our study, Hantavax elicited low neutralizing antibody responses, at least in the volunteers samples that we tested. The vaccination program, including the vaccine itself, that has been adopted by the national immunization program to protect against HFRS in Korea should be re-evaluated and re-formulated to produce a higher protective immune response rate.

Structural and functional alterations of the peritoneum after prolonged exposure to dialysis solutions: role of aminoguanidine

OBJECTIVE

The effect of long-term use of high glucose dialysate on peritoneal structure and function, and its relation with accumulation of advanced glycosylation end-product (AGE) in the peritoneum was investigated in this study.

METHODS

Dialysates with 4.25% glucose were injected into the peritoneal cavity of normal rats for 12 weeks without (PD, n = 7) and with (1 g/L, PD+AG, n = 7) aminoguanidine in their drinking water. Rats not having intraperitoneal (IP) injection served as control (n = 9). After 12 weeks of IP injection, a 2-hour peritoneal equilibration test (PET) was performed using 30 mL 4.25% glucose dialysate. Intraperitoneal volume (IPV), dialysate-to-plasma urea ratio at 2 hours (D/P2), the ratio of dialysate glucose at 2 hours to initial dialysate glucose (D2/D0), and the peritoneal fluid absorption rate (Qa) were evaluated. After the PET, samples of the parietal peritoneum were taken for hematoxylin and eosin (H&E) staining and immunohistochemical staining for AGE.

RESULTS

The IPV and D2/D0 glucose were significantly lower and Qa and D2/P2 urea significantly higher in the PD group than in the control group. Aminoguanidine reversed in part the changes in IPV and D2/P2 urea in the PD group; it had no effect on Qa and D2/D0 glucose. The H&E staining showed a linear mesothelial lining with negligible cells and capillaries in the narrow submesothelial space in the control group. Mesothelial denudation and submesothelial infiltration of monocytes and capillary formation were observed in the PD group. Mesothelial denudation was relatively intact in the PD+AG group compared with the PD group. Submesothelial monocyte infiltration and capillary formation in the PD+AG group were not as prominent as in the PD group. Positive AGE staining was found in the submesothelial space, vascular walls, and endomysium in the PD group, while it was markedly attenuated in PD+AG group and negligible in the control group.

CONCLUSION

Long-term use of high glucose solutions induced peritoneal AGE accumulation and mesothelial denudation, and increased peritoneal permeability and peritoneal fluid absorption rate. Inhibition of peritoneal AGE accumulation prevented those functional and structural damages to the peritoneum.

Hypoxia inhibits G1/S transition through regulation of p27 expression

Mammalian cellular responses to hypoxia include adaptive metabolic changes and a G1 cell cycle arrest. Although transcriptional regulation of metabolic genes by the hypoxia-induced transcription factor (HIF-1) has been established, the mechanism for the hypoxia-induced G1 arrest is not known. By using genetically defined primary wild-type murine embryo fibroblasts and those nullizygous for regulators of the G1/S checkpoint, we observed that the retinoblastoma protein is essential for the G1/S hypoxia-induced checkpoint, whereas p53 and p21 are not required. In addition, we found that the cyclin-dependent kinase inhibitor p27 is induced by hypoxia, thereby inhibiting CDK2 activity and forestalling S phase entry through retinoblastoma protein hypophosphorylation. Reduction or absence of p27 abrogated the hypoxia-induced G1 checkpoint, suggesting that it is a key regulator of G1/S transition in hypoxic cells. Intriguingly, hypoxic induction of p27 appears to be transcriptional and through an HIF-1-independent region of its proximal promoter. This demonstration of the molecular mechanism of hypoxia-induced G1/S regulation provides insight into a fundamental response of mammalian cells to low oxygen tension.

Human flap endonuclease-1: conformational change upon binding to the flap DNA substrate and location of the Mg2+ binding site

Human flap endonuclease-1 (FEN-1) is a member of the structure-specific endonuclease family and is a key enzyme in DNA replication and repair. FEN-1 recognizes the 5'-flap DNA structure and cleaves it, a specialized endonuclease function essential for the processing of Okazaki fragments during DNA replication and for the repair of 5'-end single-stranded tails from nicked double-stranded DNA substrates. Magnesium is a cofactor required for nuclease activity. We have used Fourier transform infrared (FTIR) spectroscopy to better understand how Mg2+ and flap DNA interact with human FEN-1. FTIR spectroscopy provides three fundamentally new insights into the structural changes induced by the interaction of FEN-1 with substrate DNA and Mg2+. First, FTIR difference spectra in the amide I vibrational band (1600-1700 cm(-1)) reveal a change in the secondary structure of FEN-1 induced by substrate DNA binding. Quantitative analysis of the FTIR spectra indicates a 4% increase in helicity upon DNA binding or about 14 residues converted from disordered to helical conformations. The observation that the residues are disordered without DNA strongly implicates the flexible loop region. The conversion to helix also suggests a mechanism for locking the flexible loop region around the bound DNA. This is the first direct experimental evidence for a binding mechanism that involves a secondary structural change of the protein. Second, in contrast with DNA binding, no change is observed in the secondary structure of FEN-1 upon Mg2+ binding to the wild type or to the noncleaving D181A mutant. Third, the FTIR results provide direct evidence (via the carboxylate ligand band at 1535 cm(-1)) that not only is D181 a ligand to Mg2+ in the human enzyme but Mg2+ binding does not occur in the D181A mutant which lacks this ligand.

Studies on the possible mechanisms of protective activity against alpha-amanitin poisoning by aucubin

Aucubin, an iridoid glucoside, was investigated to determine whether it has a stimulating effect on alpha-amanitin excretion in alpha-amanitin intoxicated rats, and whether there is binding activity to calf thymus DNA. High-performance liquid chromatography (HPLC) analysis of alpha-amanitin in rat urine allowed quantitative measurement of the alpha-amanitin concentration with a detection limit of 50 ng/ml. In this system, a group treated with both alpha-amanitin and aucubin showed that alpha-amanitin was excreted about 1.4 times faster than in the alpha-amanitin only treated group. Our previous results showed that the toxicity of alpha-amanitin is due to specific inhibition of RNA polymerase activity and the resultant blockage of the synthesis of certain RNA species in the nucleus. However, no significant activity change on RNA polymerase from Hep G2 cells was observed when aucubin was treated with alpha-amanitin at any concentration tested. Nevertheless, aucubigenin inhibited both DNA polymerase (IC50, 80.5 microg/ml) and RNA polymerase (IC50, 135.0 microg/ml) from the Hep G2 cells. The potential of both alpha-amanitin and aucubin to interact with DNA were examined by spectrophotometric analysis. Alpha-Amanitin showed no significant binding capacity to calf thymus DNA, but aucubin was found to interact with DNA, and the apparent binding constant (Kapp) and apparent number of binding sites per DNA phosphate (Bapp) were 0.45 x 10(4) M(-1) and 1.25, respectively.

Treatment of internal carotid artery dissections with endovascular stent placement: report of two cases

Extracranial carotid artery dissection may manifest as arterial stenosis or occlusion, or as dissecting aneurysm formation. Anticoagulation and/or antiplatelet therapy is the first-line treatment, but because it is effective and less invasive than other procedures, endovascular treatment of carotid artery dissection has recently attracted interest. We encountered two consecutive cases of trauma-related extracranial internal carotid artery dissection, one in the suprabulbar portion and one in the subpetrosal portion. We managed the patient with suprabulbar dissection using a self-expandable metallic stent and managed the patient with subpetrosal dissection using a balloon-expandable metallic stent. In both patients the dissecting aneurysm disappeared, and at follow-up improved luminal patency was observed.

Ethnic differences in the age-related distribution of serum prostate-specific antigen values: a study in a healthy Korean male population

OBJECTIVES

To further improve the use of prostate-specific antigen (PSA) as a screening test for prostate cancer in Asian countries, we sought to establish the normal distribution of serum PSA values in Korean men, because, until recently, studies conducted to establish normal serum PSA values have involved few Asian populations.

METHODS

Between May 1995 and June 1997, 5805 healthy Korean men 30 to 79 years old who visited our hospital for a routine health checkup were entered into a prospective study of early screening for prostate cancer. All men underwent detailed clinical examinations, including a digital rectal examination and serum PSA determination. All men who were more than 50 years old with abnormal digital rectal examination findings and/or an elevated serum PSA level (greater than 4.0 ng/mL) also underwent transrectal ultrasound-guided sextant biopsy. Four were found to have cancer and were excluded from the analysis.

RESULTS

The median serum PSA concentration (5th to 95th percentile range) was 0.8 ng/mL (0.2 to 1.8) for patients 30 to 39 years old (n = 1382); 0.8 ng/mL (0.2 to 2.0) for patients 40 to 49 years old (n = 1776); 0.9 ng/mL (0.2 to 2.4) for those 50 to 59 years old (n = 1775); 1.0 ng/mL (0.2 to 3.9) for men 60 to 69 years old (n = 746); and 1.3 ng/mL (0.5 to 6.3) for patients 70 to 79 years old (n = 122). The serum PSA concentration correlated with age (P <0.001), with an increase by approximately 1.2% annually, although the statistical correlation was weak (r = 0.16). Almost no change occurred in the median serum PSA value in patients 50 years old or younger; a gradual increase was observed in patients older than 50. In those 50 years old or older, the median and 95th percentile serum PSA values for Korean men were lower than those for white men.

CONCLUSIONS

Contrary to earlier observations that the serum PSA level strongly correlates with age, the influence of age on serum PSA was found to be weaker in this study. Moreover, the results also demonstrated that the distribution of the serum PSA level differs along ethnic lines. The cutoff value for serum PSA in mass screening for prostate cancer should be adjusted in nonwhite races.

The application of an anti-angiogenic gene (thrombospondin-1) in the treatment of human prostate cancer xenografts

Angiogenesis is a critical event for solid tumor growth and metastasis. Within a given microenvironment, the angiogenic response is determined in part by the balance between angiogenesis inducers and inhibitors. The aim of this study was to establish a thrombospondin-1 (TSP-1) ( an antiangiogenic gene) expression vector, and to determine the feasibility for use of TSP-1 in prostate cancer gene therapy. The results of this study showed that pCR-TSP-1, the cloned TSP-1 expression plasmid vector, expressed the TSP-1 gene efficiently in DU145, a human prostate cancer cell line. pCR -TSP-1 did not exert any significant growth inhibitory activity on the tested cell line in vitro. However, TSP-1 overexpression inhibited the growth of DU-145 xenografts in Balb/c nude mice when directly transfected with pCR-TSP-1 in combination with a liposomal agent (DOSPER). Histological analysis showed that there were extensive areas of necrosis in the TSP-1 overexpressing tumors, whereas no necrotic foci were observed in the control tumors. Furthermore, the microvessel density was lower in the TSP-1 overexpressing tumors compared to the control tumors. These results suggest that TSP-1 may be a potentially useful gene for prostate cancer gene therapy.

Rad22 protein, a rad52 homologue in Schizosaccharomyces pombe, binds to DNA double-strand breaks

DNA double-strand breaks can be introduced by exogenous agents or during normal cellular processes. Genes belonging to the RAD52 epistasis group are known to repair these breaks in budding yeast. Among these genes, RAD52 plays a central role in homologous recombination and DNA double-strand break repair. Despite its importance, its mechanism of action is not yet clear. It is known, however, that the human homologue of Rad52 is capable of binding to DNA ends in vitro. Herein, we show that Rad22 protein, a Rad52 homologue in the fission yeast Schizosaccharomyces pombe, can similarly bind to DNA ends at double-strand breaks. This end-binding ability was demonstrated in vitro by electron microscopy and by protection from exonuclease attack. We also showed that Rad22 specifically binds near double-strand break associated with mating type switching in vivo by chromatin immunoprecipitation analysis. This is the first evidence that a recombinational protein directly binds to DNA double-strand breaks in vivo.

Effect of prolonged subcutaneous implantation of peritoneal catheter on peritonitis rate during CAPD: a prospective randomized study

We conducted a prospective randomized controlled study to confirm our earlier observation that prolonged subcutaneous implantation of peritoneal catheter reduced peritonitis rate when compared to retrospective data from patients with catheters placed by conventional access technique. A total of 60 patients were randomized into two groups: 30 patients had catheters left implanted subcutaneously for 6 weeks (I) and the other 30 patients had catheters inserted by conventional technique and had 6 weeks of break-in period (C). Subgroups of 15 patients each with new and conventional techniques used Y-connector (IY, CY) and remaining patients used standard spikes (IS, CS). Mean age was 47.7 years (range 16-71); 61.0% were male and 44.1% diabetics. Peritonitis, exit site infection, simultaneous peritonitis and exit site infection, and complication related to Staphylococcus or Pseudomonas infections were observed for up to 2 years in each patient after initiation of bag exchange or until termination of CAPD by transfer to hemodialysis or by death. Total duration of observation was 493.2 patient-months for new access technique and 409.6 patient-months for conventional technique. Patients in IY group had the lowest incidence of peritonitis (1/14.9 patient-months) and exit site infection (1/16.8 patient-months) among four subgroups. Peritonitis rate in IY was significantly lower compared to CY or CS. The total peritonitis-free period in those patients who did not experience peritonitis during the observation period was also significantly longer in IY (120 patient-months) than in CY (26 patient-months), IS (10.6 patient-months), or CS (10.4 patient-months). Simultaneous peritonitis and exit site infection was observed in none of IY group but 3 episodes in CY, 4 episodes in IS, and 3 episodes in CS. The rates of complications related to Staphylococcus aureus and Pseudomonas infections were also significantly lower in IY than in CY, IS, or CS. Technique survival did not differ between the two groups. The present results confirm our previous observation that the new access technique reduces the incidence of peritonitis probably by reducing infection via periluminal route. The Y-connector system further reduces peritonitis rate by reducing infection via intraluminal route.

Identification of expressed sequence tags of watermelon (Citrullus lanatus) leaf at the vegetative stage

A cDNA library was constructed using mRNA prepared from leaves of watermelon [Citrullus lanatus (Thunb.) Matsum&Nakai] at the vegetative stage. Randomly selected cDNA clones were sequenced in order to identify potentially informative genes. Database comparisons indicated that out of the 704 watermelon cDNA clones, 399 clones (56.7 %) revealed a high degree of sequence similarity to genes from other organisms. These expressed sequence tag clones were divided into ten categories depending upon gene function. Since this kind of experiment has not previously been carried out in this genome, random nucleotide sequencing of these cDNAs could contribute considerable information concerning the novel genes in this organism.

Requirement for human AP endonuclease 1 for repair of 3'-blocking damage at DNA single-strand breaks induced by reactive oxygen species

The major mammalian apurinic/apyrimidinic (AP) endonuclease (APE1) plays a central role in the DNA base excision repair pathway (BER) in two distinct ways. As an AP endonuclease, it initiates repair of AP sites in DNA produced either spontaneously or after removal of uracil and alkylated bases in DNA by monofunctional DNA glycosylases. Alternatively, by acting as a 3'-phosphoesterase, it initiates repair of DNA strand breaks with 3'-blocking damage, which are produced either directly by reactive oxygen species (ROS) or indirectly through the AP lyase reaction of damage-specific DNA glycosylases. The endonuclease activity of APE1, however, is much more efficient than its DNA 3'-phosphoesterase activity. Using whole extracts from human HeLa and lymphoblastoid TK6 cells, we have investigated whether these two activities differentially affect BER efficiency. The repair of ROS-induced DNA strand breaks was significantly stimulated by supplementing the reaction with purified APE1. This enhancement was linearly dependent on the amount of APE1 added, while addition of other BER enzymes, such as DNA ligase I and FEN1, had no effect. Moreover, depletion of endogenous APE1 from the extract significantly reduced the repair activity, suggesting that APE1 is essential for repairing such DNA damage and is limiting in extracts of human cells. In contrast, when uracil-containing DNA was used as the substrate, the efficiency of repair was not affected by exogenous APE1, presumably because the AP endonuclease activity was not limiting. These results indicate that the cellular level of APE1 may differentially affect repair efficiency for DNA strand breaks but not for uracil and AP sites in DNA.

Diarylheptanoids with in vitro inducible nitric oxide synthesis inhibitory activity from Alnus hirsuta

Four diarylheptanoids were isolated from the leaf of Alnus hirsuta (Betulaceae) and have been assessed for nitric oxide (NO) production inhibitory effects in vitro. Oregonin (1) and hirsutanonol (2) were found to be potent inducible nitric oxide synthase (iNOS) inhibitors. Compounds 1 and 2 showed inhibition of NO synthesis in dose-dependent manners by murine macrophage-like RAW 264.7 cells stimulated with interferon-gamma (IFN-gamma) plus lipopolysaccharide (LPS). Their 50% inhibitory concentrations (IC50) were 3.8 and 14.3 microM, respectively. The inhibitory effects of these compounds on NO synthesis were due to suppression of iNOS mRNA expression as determined by Northern blotting.

Peritoneal accumulation of AGE and peritoneal membrane permeability

BACKGROUND

In continuous ambulatory peritoneal dialysis (CAPD), the peritoneal membrane is continuously exposed to high-glucose-containing dialysis solutions. Abnormally high glucose concentration in the peritoneal cavity may enhance advanced glycosylation end-product (AGE) formation and accumulation in the peritoneum. Increased AGE accumulation in the peritoneum, decreased ultrafiltration volume, and increased peritoneal permeability in long-term dialysis patients have been reported.

AIM

The purpose of the study was to evaluate the relation between peritoneal membrane permeability and peritoneal accumulation of AGE.

METHODS

Peritoneal membrane permeability was evaluated by peritoneal equilibration test (PET) using dialysis solutions containing 4.25% glucose. Serum, dialysate, and peritoneal tissue levels of AGE were measured by ELISA method using polyclonal anti-AGE antibody. Peritoneal biopsy was performed during peritoneal catheter insertion [new group (group N), n = 18] and removal [long-term group (group LT), n = 10]. Peritoneal catheters were removed due to exit-site infection not extended into the internal cuff (n = 6) and ultrafiltration failure (n = 4) after 51.6+/-31.5 months (13 - 101 months) of dialysis. PET data obtained within 3 months after the initiation of CAPD or before catheter removal were included in this study. Ten patients in group N and 4 patients in group LT were diabetic. Patients in group LT were significantly younger (46.5+/-11.1 years vs 57.5+/-1.3 years) and experienced more episodes of peritonitis (3.5+/-2.1 vs 0.2+/-0.7) than group N.

RESULTS

Peritoneal tissue AGE level in group LT was significantly higher than in group N, in both nondiabetic (0.187+/-0.108 U/mg vs 0.093+/-0.08 U/mg of hydroxyproline, p < 0.03) and diabetic patients (0.384+/-0.035 U/mg vs 0.152+/-0.082 U/mg of hydroxyproline, p < 0.03), while serum and dialysate levels did not differ between the groups in both nondiabetic and diabetic patients. Drain volume (2600+/-237 mL vs 2766+/-222 mL, p = 0.07) and D4/D0 glucose (0.229+/-0.066 vs 0.298+/-0.081, p < 0.009) were lower, and D4/P4 creatinine (0.807+/-0.100 vs 0.653+/-0.144, p< 0.0001) and D1/P1 sodium (0.886+/-0.040 vs 0.822+/-0.032, p < 0.0003) were significantly higher in group LT than in group N. On linear regression analysis, AGE level in the peritoneum was directly correlated with duration of CAPD (r = 0.476, p = 0.012), number of peritonitis episodes (r = 0.433, p = 0.0215), D4/P4 creatinine (r = 0.546, p < 0.027), and D1/P1 sodium (r = 0.422, p = 0.0254), and inversely correlated with drain volume (r = 0.432, p = 0.022) and D4/D0 glucose (r = 0.552, p < 0.0023). AGE level in the peritoneal tissue and dialysate were significantly higher in diabetics than in nondiabetics in group LT, while these differences were not found in group N. Serum AGE level did not differ between nondiabetics and diabetics in either group N or group LT. Drain volume and D4/D0 glucose were lower and D4/P4 creatinine and D1/P1 sodium higher in diabetics than in nondiabetics in both groups.

CONCLUSION

Peritoneal accumulation of AGE increased with time on CAPD and number of peritonitis episodes, and was directly related with peritoneal permeability. Peritoneal AGE accumulation and peritoneal permeability in diabetic patients were higher than in nondiabetic patients from the beginning of CAPD.

Laser soldering and welding for ossicular reconstruction: an in vitro test

To evaluate the possibility of laser application in ossicular reconstruction, soldering and welding of bony tissue with proteineous materials was performed by using a CO (2) laser, and the bonding strength of these materials was measured with a gradual weighing system. The soldered and welded surface of bone was observed with a scanning electron microscope. Additionally, welding of human ossicles and synthetic materials was experimentally tried with lasers, and morphologic changes were observed and recorded. A scanning electron microscopic examination was also done. A 40% albumin solution and commercial fibrin glue showed the best bonding strength. Bridging of denatured protein solder may be a mechanism of bonding. Polycel was melted by using a laser beam, and melted Polycel covered the surface of the ossicle. However, the bonding strength was not enough to use, and exact measurement of bonding strength was not possible. These results suggested the possibility of laser soldering and welding in ossicular reconstruction, especially with ossicle or cortical bone.

Laser Soldering and Welding for Ossicular Reconstruction: An in Vitro Test

To evaluate the possibility of laser application in ossicular reconstruction, soldering and welding of bony tissue with proteineous materials was performed by using a Co2 laser, and the bonding strength of these materials was measured with a gradual weighing system. The soldered and welded surface of bone was observed with a scanning electron microscope. Additionally, welding of human ossicles and synthetic materials was experimentally tried with lasers, and morphologic changes were observed and recorded. A scanning electron microscopic examination was also done. A 40% albumin solution and commercial fibrin glue showed the best bonding strength. Bridging of denatured protein solder may be a mechanism of bonding. Polycel was melted by using a laser beam, and melted Polycel covered the surface of the ossicle. However, the bonding strength was not enough to use, and exact measurement of bonding strength was not possible. These results suggested the possibility of laser soldering and welding in ossicular reconstruction, especially with ossicle or cortical bone.

Measurement of surface area in human mastoid air cell system

The total surface areas of human mastoid air cells were measured using digital CT scans. Using 24 normal ears, the lining of the mastoid air cells was digitally scanned, traced and analysed. The mean surface area of the mastoid air cell system was 167.0 cm2 and ranged from 74.78 to 330.01 cm2. The volume was also measured, the mean being 10.43 cm3 ranging from 6.25 to 20.52 cm3. The correlation coefficient between surface area and volume was 0.95. These results indicate that well pneumatized mastoid air cells serve to provide an extremely large surface area in the temporal bone which in normal mastoid air cells is proportional to the volume.

Diarylheptanoids from the leaves of Alnus hirsuta Turcz

Diarylheptanoids, (5S)-1,7-bis-(3,4-dihydroxyphenyl)-5-hydroxyheptane-3-one (1, hirsutanonol), (5S)-1,7-bis-(3,4-dihydroxyphenyl)-heptane-3-one-5-O-beta-D-xylopyranosi de (2, oregonin), (5R)-1,7-bis-(3,4-dihydroxyphenyl)-heptane-5-O-beta-D-xylopyranoside (3), and (5R)-1,7-bis-(3,4-dihydroxyphenyl)-heptane-5-O-beta-D-glucopyranoside (4) were isolated from the leaves of Alnus hirsuta Turcz. The structures of these compounds were identified based on the spectral and physicochemical data.

The changing epidemiology of hepatitis A in children and the consideration of active immunization in Korea

Currently, Korea is a low endemicity country for HAV, especially in children. However, recent reports of hepatitis A outbreaks show that there has been a shift of disease incidence to adolescents and young adults, with 2 cases of acute liver failure in one reported outbreak. We need to study the immune status for HAV in order to provide information for the establishment of preventive measures and possible consequences of HAV in Korea. A total of 334 infants, children and adolescents less than 20 years of age living in rural areas of Kyonggi Province, Korea were evaluated for anti-HAV immune status in 1996. Five hundred and eighty-four primary school children living in the same area were separately evaluated for the natural seroconversion rate between 1993 and follow-up samples taken in 1996. Anti-HAV IgG antibody was measured by enzyme immunoassay (HAVAB EIA kit, Abbott Laboratories, Chicago, Illinois, USA). In comparison with previous reports of seroprevalence rates, our data confirmed a dramatic drop in seroprevalence rates among children and adolescents under 20 years of age living in rural areas, from over 63.8% two decades ago to 4.6% in 1996. Natural acquisition of HAV antibody in primary school children rarely occurs, registering only 0.5% during three years. Several outbreaks in young adults during 1996-1998 suggested that immunity against HAV in this population is so low that massive outbreaks are unavoidable. Teenagers and young adults, especially soldiers, who are likely to be exposed to contaminated food or water, would also have a greater risk of hepatitis A. Immunizing children with HAV vaccine as a routine schedule should also be considered in Korea in the future, particularly if the disease burden could be estimated and the cost-effectiveness of the vaccine could be proved.

Development of a new plasmid vector with PSA-promoter and enhancer expressing tissue-specificity in prostate carcinoma cell lines

Differential expression of the desired gene product in the target tissue is central to the concept of gene therapy. One approach is to use a tissue-specific promoter to drive therapeutic genes, such as the p53 tumor suppressor gene. To determine the feasibility of tissue-specific gene therapy for prostate cancer using prostate specific antigen (PSA) promoter and/or enhancer, in this study, we developed a tissue specific expression vector using a PSA promoter and enhancer. Our results showed that the cloned PSA promoter actively drives gene expression in the PSA-producing prostate cancer cell line (LNCaP). However, barely any promoter activity was detected in the non-PSA producing prostate cancer cell lines (DU145, PC-3) or the non-prostate cell lines (HEK-293, SAOS-2). The wild-type p53 gene driven by this PSA-promoter efficiently suppressed the growth of LNCaP. Moreover, p53 driven by the PSA enhancer-promoter cassette more efficiently suppressed the growth of the PSA-producing prostate cancer cell line (LNCaP) in vitro. This suggest that we were able to manage the tissue specificity by PSA enhancer and promoter. Additionally, the juxtaposed enhancer-promoter cassette showed great enhancement of p53 expression and apoptosis in vitro. Taken together, these results show that PSA enhancer-promoter may be a potential tool for gene therapy for prostate cancer.

Hepatic cavernous hemangioma in cirrhotic liver: imaging findings

OBJECTIVE

To document the imaging findings of hepatic cavernous hemangioma detected in cirrhotic liver.

MATERIALS AND METHODS

The imaging findings of 14 hepatic cavernous hemangiomas in ten patients with liver cirrhosis were retrospectively analyzed. A diagnosis of hepatic cavernous hemangioma was based on the findings of two or more of the following imaging studies: MR, including contrast-enhanced dynamic imaging (n = 10), dynamic CT (n = 4), hepatic arteriography (n = 9), and US (n = 10).

RESULTS

The mean size of the 14 hepatic hemangiomas was 0.9 (range, 0.5-1.5) cm in the longest dimension. In 11 of these (79%), contrast-enhanced dynamic CT and MR imaging showed rapid contrast enhancement of the entire lesion during the early phase, and hepatic arteriography revealed globular enhancement and rapid filling-in. On contrast-enhanced MR images, three lesions (21%) showed partial enhancement until the 5-min delayed phases. US indicated that while three slowly enhancing lesions were homogeneously hyperechoic, 9 (82%) of 11 showing rapid enhancement were not delineated.

CONCLUSION

The majority of hepatic cavernous hemangiomas detected in cirrhotic liver are small in size, and in many, hepatic arteriography and/or contrast-enhanced dynamic CT and MR imaging demonstrates rapid enhancement. US, however, fails to distinguish a lesion of this kind from its cirrhotic background.

Development of lupus in BXSB mice is independent of IL-4

Although systemic lupus erythematosus appears to be a humorally mediated disease, both Th1 and Th2 type responses have been implicated in its pathogenesis. The Th1 response, as exemplified by IFN-gamma production, has been uniformly shown in mouse lupus models to be critical for disease induction. The role of Th2 type responses, however, is more complicated, with some studies showing detrimental and others beneficial effects of IL-4 in these models. To further address this issue, we generated and analyzed IL-4 gene-deficient BXSB mice. Mice homozygous for this deletion had significantly lower serum levels of total IgG1 compared with wild-type BXSB, consistent with the lack of IL-4. However, no significant differences were observed in mortality, spleen weight, severity of glomerulonephritis, levels of anti-chromatin and anti-ssDNA Abs, or frequency of activated (CD44high) CD4+ T cells. The anti-chromatin Ab isotype response was virtually all Th1 type in both the knockout and wild-type BXSB. These findings directly demonstrate that IL-4 and, by inference, Th2 cells are not obligatory participants in the induction and maintenance of lupus in this strain.

Inhibition of FEN-1 processing by DNA secondary structure at trinucleotide repeats

The mechanism by which trinucleotide expansion occurs in human genes is not understood. However, it has been hypothesized that DNA secondary structure may actively participate by preventing FEN-1 cleavage of displaced Okazaki fragments. We show here that secondary structure can, indeed, play a role in expansion by a FEN-1-dependent mechanism. Secondary structure inhibits flap processing at CAG, CGG, or CTG repeats in a length-dependent manner by concealing the 5' end of the flap that is necessary for both binding and cleavage by FEN-1. Thus, secondary structure can defeat the protective function of FEN-1, leading to site-specific expansions. However, when FEN-1 is absent from the cell, alternative pathways to simple inhibition of flap processing contribute to expansion.

Reconstitution of proliferating cell nuclear antigen-dependent repair of apurinic/apyrimidinic sites with purified human proteins

An apurinic/apyrimidinic (AP) site is one of the most abundant lesions spontaneously generated in living cells and is also a reaction intermediate in base excision repair. In higher eukaryotes, there are two alternative pathways for base excision repair: a DNA polymerase beta-dependent pathway and a proliferating cell nuclear antigen (PCNA)-dependent pathway. Here we have reconstituted PCNA-dependent repair of AP sites with six purified human proteins: AP endonuclease, replication factor C, PCNA, flap endonuclease 1 (FEN1), DNA polymerase delta, and DNA ligase I. The length of nucleotides replaced during the repair reaction (patch size) was predominantly two nucleotides, although longer patches of up to seven nucleotides could be detected. Neither replication protein A nor Ku70/80 enhanced the repair activity in this system. Disruption of the PCNA-binding site of either FEN1 or DNA ligase I significantly reduced efficiency of AP site repair but did not affect repair patch size.

Peritoneal transport of glucose in rat

OBJECTIVE

To evaluate the convective transport characteristics of glucose and the effect of high glucose and insulin during experimental peritoneal dialysis in rat.

METHODS

Male Sprague-Dawley rats weighing 300-400 g were used in this study. Mannitol (5%) was used as osmotic agent. Glucose was added to dialysis solution to yield a concentration of 100 mg/dL (group 1) or 300 mg/dL (group 2). Mannitol solution (5%) containing the same concentration of electrolytes and lactate but without glucose was used as control (group 3). In group 2, blood sugar was maintained at approximately 300 mg/dL by continuous intravenous infusion of 25% glucose solution and 0.9% NaCl solution. A 2-hour dwell study was performed with 30 mL of test solutions. Intraperitoneal volume was calculated by volume marker (18.5 kBq of 131I-human radioiodinated serum albumin, RISA) dilution with corrections made for the elimination of RISA from the peritoneal cavity (K(E)) and sample volume. The diffusive mass transport coefficient (K(BD)) and sieving coefficient (S(BRF)) were calculated by using the Babb-Randerson-Farrell model. S was also calculated directly by using isocratic methods (S(I)). The peritoneal fluid absorption rate (K(E)) was taken into account for the calculation of S(I).

RESULTS

Intraperitoneal volume was significantly higher in group 2 compared with groups 1 and 3. Peritoneal fluid absorption rate, K(E), was similar in all three groups. S(BRF) and S(I) for glucose were significantly lower in group 2 compared with groups 1 and 3. S(BRF) for glucose in group 2 was below zero and S(I) near zero. K(BD) for glucose was significantly higher in group 2 than in groups 1 and 3. Plasma and dialysate concentrations of insulin increased during the initial hour and then decreased to the baseline value in groups 1 and 3, while in group 2 it continuously increased.

CONCLUSION

Significantly lower sieving coefficients for glucose in the high glucose and high insulin group suggest that transport mechanisms other than simple passive transport are involved in peritoneal glucose transport, and that high glucose per se and/or high insulin may be important factors that determine glucose transport characteristics.

A novel role in DNA metabolism for the binding of Fen1/Rad27 to PCNA and implications for genetic risk

Fen1/Rad27 nuclease activity, which is important in DNA metabolism, is stimulated by proliferating cell nuclear antigen (PCNA) in vitro. The in vivo role of the PCNA interaction was investigated in the yeast Rad27. A nuclease-defective rad27 mutation had a dominant-negative effect that was suppressed by a mutation in the PCNA binding site, thereby demonstrating the importance of the Rad27-PCNA interaction. The PCNA-binding defect alone had little effect on mutation, recombination, and the methyl methanesulfonate (MMS) response in repair-competent cells, but it greatly amplified the MMS sensitivity of a rad51 mutant. Furthermore, the PCNA binding mutation resulted in lethality when combined with a homozygous or even a heterozygous pol3-01 mutation in the 3'-->5' exonuclease domain of DNA polymerase delta. These results suggest that phenotypically mild polymorphisms in DNA metabolic proteins can have dramatic consequences when combined.

Prospective evaluation of perinatal risk factors for cerebral palsy and delayed development in high risk infants

Prematurity, intrauterine infection and perinatal brain injury have been reported to be significant risk factors of cerebral palsy (CP). We examined the perinatal predictors of cerebral palsy and delayed development (DD) in 184 high risk infants. Thirty-five infants were diagnosed as cerebral palsy and delayed development at 12 months corrected age. Antenatal, intrapartum, and neonatal factors were prospectively evaluated in 2 groups of high risk infants compared with controls; Group A (n = 79), infants weighing less than 2,000 g; Group B (n = 43), infants weighing 2,000 g or more. In univariate analysis, there were no significant antenatal and intrapartum factors associated with cerebral palsy and delayed development in either group. We found that significant postnatal risk factors of CP in group A included sepsis (p = 0.008), BPD (bronchopulmonary dysplasia) (p = 0.028), IVH (intraventricular hemorrhage) (p = 0.042), ventriculomegaly (VM) (p = 0.001) and a longer duration of mechanical ventilation (p = 0.001); while in group B, sepsis (p = 0.047) and neonatal seizure (p = 0.027) were significant risk factors. In multivariate analysis, sepsis in group B was a moderate risk factor of CP (OR (odds ratio) 1.47; 95% CI (confidence interval) 1.02-2.13). In conclusion, neonatal sepsis may contribute to the development of cerebral palsy and delayed development. We suggest that high risk infants who have sepsis should be carefully followed for cerebral palsy and delayed development. The prevention of cerebral palsy may be feasible by decreasing neonatal risk factors such as sepsis during the neonatal period.

Standardization of the nationwide health examination in Korea

The Korea Medical Insurance Corporation has held the periodic Health Examination for the public servants and teachers from 1977 as a nationwide health preventive task. But the Health Examination result is not computerized rather than paperwork, so the use of the Health Examination is limited and the results of Health Examination can not be stored or interchangeable between hospitals or health examination centers in this system. So we planed the Standardization of the Nationwide Health Examination project and developed the Health Examination computer program in 1996. The object of standardized program is to contribute to cost-effective analysis of each item or other studies about the factors influences development of diseases. And now, an Exhibition work for the standardization is being held with the Health Examination computer program. At the ending of the Exhibition work, we will evaluation and revision the computerized program for standardization process.

p27 and Rb are on overlapping pathways suppressing tumorigenesis in mice

The commitment of cells to replicate and divide correlates with the activation of cyclin-dependent kinases and the inactivation of Rb, the product of the retinoblastoma tumor suppressor gene. Rb is a target of the cyclin-dependent kinases and, when phosphorylated, is inactivated. Biochemical studies exploring the nature of the relationship between cyclin-dependent kinase inhibitors and Rb have supported the hypothesis that these proteins are on a linear pathway regulating commitment. We have been able to study this relationship by genetic means by examining the phenotype of Rb+/-p27-/- mice. Tumors arise from the intermediate lobe cells of the pituitary gland in p27-/- mice, as well as in Rb+/- mice after loss of the remaining wild-type allele of Rb. Using these mouse models, we examined the genetic interaction between Rb and p27. We found that the development of pituitary tumors in Rb+/- mice correlated with a reduction in p27 mRNA and protein expression. To determine whether the loss of p27 was an indirect consequence of tumor formation or a contributing factor to the development of this tumor, we analyzed the phenotype of Rb+/-p27-/- mice. We found that these mice developed pituitary adenocarcinoma with loss of the remaining wild-type allele of Rb and a high-grade thyroid C cell carcinoma that was more aggressive than the disease in either Rb+/- or p27-/- mice. Importantly, we detected both pituitary and thyroid tumors earlier in the Rb+/-p27-/- mice. We therefore propose that Rb and p27 cooperate to suppress tumor development by integrating different regulatory signals.

Primary and booster immune responses to SA14-14-2 Japanese encephalitis vaccine in Korean infants

Attenuated SA14-14-2 Japanese encephalitis (JE) vaccine has been administered safely and effectively to more than 100 million children in China since 1988 and recently, licensure of the vaccine in Korea has been sought. In the first clinical evaluation of the vaccine outside of China, we monitored side effects in 84 children and evaluated antibody responses to a single dose given as primary JE vaccination in 68 children, 1-3 years old (mean age 27 months). No significant adverse events were noted. Neutralizing antibodies (geometric mean titer [GMT] of 188) were produced in 96% of the 68 subjects. In 10 other children who previously had been immunized with two or three doses of inactivated JE vaccine, the booster administration of SA14-14-2 vaccine produced an anamnestic response in all, with a GMT of 3378. In a comparison group of 25 children previously immunized with two doses of inactivated vaccine, neutralizing antibody titers were detected in 16 (64%). Viral specific IgM was detected in nine primary vaccinees (13%) but in others, IgM may have declined to undetectable levels in the four week postimmunization sample. Live attenuated SA14-14-2 JE vaccine is a promising alternative to the only commercially available JE vaccine for national childhood immunization programs in Asia.

Radiation-induced assembly of Rad51 and Rad52 recombination complex requires ATM and c-Abl

Cells from individuals with the recessive cancer-prone disorder ataxia telangiectasia (A-T) are hypersensitive to ionizing radiation (I-R). ATM (mutated in A-T) is a protein kinase whose activity is stimulated by I-R. c-Abl, a nonreceptor tyrosine kinase, interacts with ATM and is activated by ATM following I-R. Rad51 is a homologue of bacterial RecA protein required for DNA recombination and repair. Here we demonstrate that there is an I-R-induced Rad51 tyrosine phosphorylation, and this induction is dependent on both ATM and c-Abl. ATM, c-Abl, and Rad51 can be co-immunoprecipitated from cell extracts. Consistent with the physical interaction, c-Abl phosphorylates Rad51 in vitro and in vivo. In assays using purified components, phosphorylation of Rad51 by c-Abl enhances complex formation between Rad51 and Rad52, which cooperates with Rad51 in recombination and repair. After I-R, an increase in association between Rad51 and Rad52 occurs in wild-type cells but not in cells with mutations that compromise ATM or c-Abl. Our data suggest signaling mediated through ATM, and c-Abl is required for the correct post-translational modification of Rad51, which is critical for the assembly of Rad51 repair protein complex following I-R.

Multifocal meningioangiomatosis: a report of two cases

We report the CT and MR findings in two patients with multifocal meningioangiomatosis, neither of whom had a family history or stigmata of neurofibromatosis. All lesions were located in the cortical and subcortical areas and had round dense calcifications with eccentric cysts. The masses were associated with surrounding edema and gliosis.

Proliferating cell nuclear antigen facilitates excision in long-patch base excision repair

There are two distinct pathways for the removal of modified DNA bases through base excision repair (BER) in vertebrates. Following 5' incision by AP endonuclease, the pathways diverge as two different excision mechanisms are possible. In short-patch repair, DNA polymerase beta accounts for both excision activity and single nucleotide repair synthesis. In long-patch repair, the damage-containing strand is excised by the structure-specific endonuclease FEN-1 and approximately 2-8 nucleotides are incorporated by proliferating cell nuclear antigen (PCNA)-dependent synthesis. PCNA is an accessory factor of DNA polymerases delta and epsilon that is required for DNA replication and repair. PCNA binds to FEN-1 and stimulates its nuclease activity, but the physiological significance of this interaction is unknown. The importance of the PCNA-FEN-1 interaction in BER was investigated. In a reconstituted BER assay system containing FEN-1, omission of PCNA caused the accumulation of pre-excision reaction intermediates which could be converted to completely repaired product by addition of PCNA. When dNTPs were omitted from the reaction to suppress repair synthesis, PCNA was required for the formation of excised reaction intermediates. In contrast, a PCNA mutant that could not bind to FEN-1 was unable to stimulate excision. To further study this effect, a mutant of FEN-1 was identified that retained full nuclease activity but was specifically defective in binding to PCNA. The mutant FEN-1 exhibited one-tenth the specific activity of wild type FEN-1 in the reconstituted BER assay, and this repair defect was due to a kinetic block at the excision step as evidenced by the accumulation of pre-excision intermediates when dNTPs were omitted. These results indicate that PCNA facilitates excision during long-patch BER through its interaction with FEN-1.

Structural changes measured by X-ray scattering from human flap endonuclease-1 complexed with Mg2+ and flap DNA substrate

Human flap endonuclease-1 (FEN-1) is a member of the structure-specific endonuclease family and is essential in DNA replication and repair. FEN-1 has specific endonuclease activity for repairing nicked double-stranded DNA substrates that have the 5'-end of the nick expanded into a single-stranded tail, and it is involved in processing Okazaki fragments during DNA replication. Magnesium is a cofactor required for nuclease activity. We used small-angle x-ray scattering to obtain global structural information pertinent to nuclease activity from FEN-1, the D181A mutant, the wild-type FEN-1. 34-mer DNA flap complex, and the D181A.34-mer DNA flap complex. The D181A mutant, which has Asp-181 replaced by Ala, selectively binds to the flap structure, but has lost its cleaving activity. Asp-181 is thought to be involved in Mg2+ binding at the active site (Shen, B., Nolan, J. P., Sklar, L. A., and Park, M. S. (1996) J. Biol. Chem. 271, 9173-9176). Our data indicate that FEN-1 and the D181A mutant each have a radius of gyration of approximately 26 A, and the effect of Mg2+ on the scattering from the proteins alone is insignificant. The 34-mer DNA fragment was constructed such that it readily forms a 5'-flap structure. The formation of the flap conformation of the DNA substrate was evident by both the extrapolated Io scattering and radius of gyration and was supported by NMR spectrum and nuclease assays. In the absence of magnesium, the FEN-1.34-mer DNA flap complex has an Rg value of approximately 34 A, whereas the D181A.34-mer DNA flap complex self-associates, suggesting that a significant protein conformational change occurs by addition of the flap DNA substrate and that Asp-181 is crucial for proper binding of the protein to the DNA substrate. A time course change in the scattering profiles arising from magnesium activation of the FEN-1.34-mer DNA flap complex is consistent with the protein completely releasing the DNA substrate after cleavage.

Antibiotic use at a pediatric age

For infections in infants and children, the successful antibiotic treatment depends primarily on rapid diagnosis of the disease, identification of pathogenic microorganisms, and appropriate application of specialized pharmacokinetic and pharmacodynamic knowledge of antibiotics in children. In infants and children, the absorption, distribution, metabolism, and excretion of drugs may differ considerably in comparison with adults. Because of known toxicity, certain drugs such as chloramphenicol in high doses, the sulfonamides, and tetracycline should not be used in neonates. In this article, we describe these peculiarities of children and discuss the proper use of antibiotics in children.