[Expression of urokinase-type plasminogen activator and its receptor protein in synovial tissues from osteoarthritis]

OBJECTIVE

To study the expression of urokinase-type plasminogen activator (uPA) and its receptor (uPAR) in the synovial tissures, and the significance of uPA and uPAR in degradation of extracellular matrices in osteoarthritis (OA), then analyse the possible relationship between uPA and uPAR.

METHODS

Immunohistochemical analysis technique was used to detect uPA and uPAR protein expression and distribution in synovial tissues in 26 OA patients and 10 mormal individuals.

RESULTS

Positive staining of uPA and uPAR protein were detected in 19 cases in the 26 OA samples (73%), while only 2 positive cases were seen in the 10 mormal tissues (20%). The expression rate of uPA protein was markedly higher in OA than in the normal (P < 0.01). The expression of uPAR was seen in 14 cases in all 26 OA samples (54.6%), while there was only one case in 10 normal samples (10%), the positive rate was significantly higher in OA than in normal samples (P < 0.05). Positive expression of uPA and uPAR proteins were found in synovial lining cells, mononuclear cells, macrophage-like cells and endothelial cells. Using the correction analysis, we found a positive correlation between uPA and uPAR reactivity in the synovial tissues in OA (r = 0.920, P < 0.01).

CONCLUSIONS

The high expression of uPA and uPAR protein in OA synovial tissues indicate that the uPA system may play an important role in the process of synovitis and degradation of OA cartilage extracellular matrices. In the pathologic process of OA, uPA and uPAR coordinate each other, lead to the genesis and development of OA cartilage degradation.

Fever-range hyperthermia dynamically regulates lymphocyte delivery to high endothelial venules

Fever is associated with increased survival during acute infection, although its mechanism of action is largely unknown. This study found evidence of an unexpectedly integrated mechanism by which fever-range temperatures stimulate lymphocyte homing to secondary lymphoid tissues by increasing L-selectin and alpha4beta7 integrin-dependent adhesive interactions between circulating lymphocytes and specialized high endothelial venules (HEV). Exposure of splenic lymphocytes in vivo to fever-like whole-body hyperthermia (WBH; 39.8 +/- 0.2 degrees C for 6 hours) stimulated both L-selectin and alpha4beta7 integrin-dependent adhesion of lymphocytes to HEV under shear conditions in lymph nodes and Peyer patches. The adhesiveness of HEV ligands for L-selectin and alpha4beta7 integrin (ie, peripheral lymph node addressin and mucosal addressin cell adhesion molecule-1) also increased during WBH or febrile responses associated with lipopolysaccharide-induced or turpentine-induced inflammation. Similar increases in HEV adhesion occurred during hyperthermia treatment of lymph node and Peyer patch organ cultures in vitro, indicating that the local lymphoid tissue microenvironment is sufficient for the hyperthermia response. In contrast, WBH did not augment adhesion in squamous endothelium of nonlymphoid tissues. Analysis of homing of alpha4beta7(hi) L-selectin(lo) murine TK1 cells and L-selectin(hi) alpha4beta7 integrin-negative 300.19/L-selectin transfectant cells showed that fever-range temperatures caused a 3- to 4-fold increase in L-selectin and alpha4beta7 integrin-dependent trafficking to secondary lymphoid tissues. Thus, enhanced lymphocyte delivery to HEV by febrile temperatures through bimodal regulation of lymphocyte and endothelial adhesion provides a novel mechanism to promote immune surveillance.

[Clinical use of interlocking intramedullary nail treating in complex and nonunion fracture of femur and tibia]

Fifty-one complex and nonunion fractures of femur and tibia in forty eight patients were treated with interlocking intramedullary nail. All patients were followed-up for 6 to 29 months to evaluate the curative effect. Forty-nine fractures in forty-six patients were healed(95.8%). The time of healing was 16 weeks(10-24 weeks) in femur and 18 weeks (12-28 week) in tibia in fresh fracture, and 20 weeks(14-46 weeks) in femur nonunion and 18 weeks (12-28 weeks) in tibia nonunion. In femur, the efficacy of 28 cases was excellent or good (93.3%), and 2 cases mediate (6.7%); in tibia, 18 cases were all assessed as excellent or good. The complications were observed in 8 patients (16.67%), including distal screw misinserting, extremity shortening, screw loosening, distal shaft fracture and fracture nonunion. The results suggest that interlocking intramedullary nail can be used in many kinds of femur and tibia fracture with satisfactory result, especially in the complex fracture and nonunion after fixation failure.

Therapeutic effect of gypenoside on chronic liver injury and fibrosis induced by CCl4 in rats

Gypenoside is a saponins extract derived from the Gynostemma pentaphyllum. The purpose of this study was to evaluate the hepatoprotective and antifibrotic potential of Gypenoside on chronic liver injury induced by CCl4 for 8 wks. The results indicated that the increase of SGOT, SGPT activities in CCl4 liver injury were significantly reduced by treatment with Gypenoside. It also elevated the A/G ratio. For the study of anti-fibrotic potential, Gypenoside reduced the collagen content by 33%. These phenomena were confirmed by pathologic observation; thinner bands of liver collagen were found. The results suggest that Gypenoside has hepatoprotective and anti-fibrotic activities.

Crystal structure and site-directed mutagenesis studies of N-carbamoyl-D-amino-acid amidohydrolase from Agrobacterium radiobacter reveals a homotetramer and insight into a catalytic cleft

The N-carbamoyl-D-amino-acid amidohydrolase (D-NCAase) is used on an industrial scale for the production of D-amino acids. The crystal structure of D-NCAase was solved by multiple isomorphous replacement with anomalous scattering using xenon and gold derivatives, and refined to 1.95 A resolution, to an R-factor of 18.6 %. The crystal structure shows a four-layer alpha/beta fold with two six-stranded beta sheets packed on either side by two alpha helices. One exterior layer faces the solvent, whereas the other one is buried and involved in the tight intersubunit contacts. A long C-terminal fragment extends from a monomer to a site near a dyad axis, and associates with another monomer to form a small and hydrophobic cavity, where a xenon atom can bind. Site-directed mutagenesis of His129, His144 and His215 revealed strict geometric requirements of these conserved residues to maintain a stable conformation of a putative catalytic cleft. A region located within this cleft involving Cys172, Glu47, and Lys127 is proposed for D-NCAase catalysis and is similar to the Cys-Asp-Lys site of N-carbamoylsarcosine amidohydrolase. The homologous active-site framework of these enzymes with distinct structures suggests convergent evolution of a common catalytic mechanism.

Hypogammaglobulinemia and reduced numbers of B-cells in children with myelodysplastic syndrome

BACKGROUND

Immunodeficiency in pediatric patients with myelodysplastic syndrome (MDS) has not been described. We report the clinical course of three children with MDS, hypogammaglobulinemia, and reduced numbers of B-cells and B-cell precursors.

OBSERVATIONS

Three patients with recurrent infection who were younger than 1-year-old had MDS of the refractory anemia (RA) subtype diagnosed. All had reduced numbers of circulating B-cells and hypogammaglobulinemia. In two patients, cytogenetic studies revealed a monosomy 7 karyotype and bone marrow studies showed decreased numbers of CD34+ progenitor cells and CD 19+ B-cells. Both patients had prolonged courses (7 yrs 10 mos and 6 yrs 9 mos) characterized by recurrent infection and slowly progressive pancytopenia. Both received allogeneic bone marrow transplantation (BMT). The third patient had normal cytogenetic studies and a normal number of CD34+ progenitors but decreased CD19+ B-cells in the bone marrow. She had a stable course with refractory anemia over the course of 7 years.

CONCLUSIONS

Pediatric patients with MDS may have hypogammaglobulinemia and reduced numbers of B-cells. These findings do not preclude a relatively stable and prolonged clinical course. Children with newly diagnosed MDS should have an immunologic evaluation in addition to their hematologic assessment.

Improved cerebrovascular patency following therapy in patients with sickle cell disease: initial results in 4 patients who received HLA-identical hematopoietic stem cell allografts

To test whether magnetic resonance angiography can document the evolution of vasculopathy in patients with sickle cell disease, we reviewed records to identify all patients who underwent magnetic resonance angiography from 1993 to 1999. Of 512 angiographies performed, 105 were of sickle cell disease patients, and 24 sickle cell disease patients 7 years of age or older underwent baseline and follow-up examinations. Films were paired by patient, blinded as to examination date and treatment, and quantitatively compared. Four patients who received allogeneic bone marrow transplantation were compared to 7 patients who received other therapy and to 13 untreated patients. Quantitative analysis revealed a 10% increase in the measured diameter of 64 vessels (p = 0.001) following any treatment. Patients who had undergone allogeneic bone marrow transplantation exhibited a 12% increase in the lumen of 22 vessels (p = 0.041), whereas patients treated with chronic transfusion or hydroxyurea exhibited an 8% increase in 42 vessels (p = 0.016). In 2 patients with severe stenosis, the artery normalized after transplantation, and the blood flow rate was reduced in all patients who underwent transplantation. In untreated patients, there was a trend for the size of the arterial lumen to decrease, which is consistent with disease progression. Results suggest that treatment can reverse progression of vasculopathy. Bone marrow transplantation may enable stenoses to heal and can substantially reduce cranial blood velocity, suggesting that allogeneic bone marrow transplantation may prevent infarction or brain damage.

Expression and binding analysis of GST-VacA fusions reveals that the C-terminal approximately 100-residue segment of exotoxin is crucial for binding in HeLa cells

The Helicobacter pylori toxin VacA induces intracellular vacuolation and plays an essential role in H. pylori-related diseases. The mature exotoxin is divided into two domains, P37 and P58. A soluble form of VacA fused with GST was expressed in Escherichia coli. Although the soluble fusion lacked vacuolating activity after cleavage by thrombin, it had a binding affinity similar to that of the native VacA. Moreover, it blocked the vacuolating activity induced by the native toxin. Different C-terminal truncated fusions were generated (GST-P72, GST-P53, and GST-P37) and were also produced in a soluble form. A significantly reduced binding activity was seen for GST-P72 and nearly no specific association was detected for GST-P37. Our results suggested that the whole P58 fragment contributed to the cell binding activity in HeLa cells, particularly in the C-terminal approximately 100-residue region.

Reversal of optic canal stenosis in osteopetrosis after bone marrow transplant

PURPOSE

To describe a patient with infantile osteopetrosis and optic atrophy secondary to optic canal stenosis who demonstrated optic canal enlargement after bone marrow transplant.

METHODS

Case report. A 3-month-old infant with infantile "malignant" osteopetrosis underwent ophthalmic examination, including visual evoked potentials, electroretinogram, and computed tomography (CT). Bone marrow transplant was performed at 8 months of age.

RESULTS

Examination revealed visual loss and optic atrophy, left eye greater than right eye, secondary to optic canal stenosis. Flash visual evoked potentials revealed a normal waveform in both eyes with increased latency in the left eye. Electroretinogram was normal in both eyes. CT after bone marrow transplant showed enlargement of the optic canals. Vision remains stable 43 months after bone marrow transplant.

CONCLUSIONS

Bone marrow transplant in infantile osteopetrosis may be followed by reversal of optic canal stenosis and preservation of vision.

Granulocyte-macrophage colony-stimulating factor in the treatment of neonates with neutropenia and sepsis

To evaluate the efficacy of granulocyte-macrophage colony-stimulating factor (GM-CSF) in improving neutrophil counts and survival of neutropenic septic neonates, the authors studied 8 neonates with gestational or postconceptional age at least 30 weeks; weight at least 1000 g; serious infection with concomitant neutropenia (absolute neutrophil count [ANC] < 3.0 x 10(9)/L) or leukopenia (white blood cell count < 5.0 x 10(9)/L) and anticipated survival at least 48 h. Patients received 5 micrograms/kg of GM-CSF intravenously for 5 consecutive days or until the ANC reached 20 x 10(9)/L. Clinical parameters and complete blood counts were monitored. Prestudy ANCs ranged from 0.05 to 2.7 x 10(9)/L. Four patients had positive blood cultures, 4 had necrotizing enterocolitis, and 1 was in septic shock. All patients had elevated C-reactive protein. All patients had resolution of neutropenia and survived the septic episodes. The use of GM-CSF in these patients merits further exploration.

Multicenter comparison of magnetic resonance imaging and transcranial Doppler ultrasonography in the evaluation of the central nervous system in children with sickle cell disease

PURPOSE

To compare the results of standardized magnetic resonance imaging (MRI) of the brain and transcranial Doppler (TCD) ultrasonography of cerebral arteries in school-aged children with sickle cell disease to determine the correlation between these two different neurodiagnostic tests.

PATIENTS AND METHODS

Data were analyzed from 78 children with sickle cell disease (mean age 11 yrs) who participated in both the Cooperative Study of Sickle Cell Disease (CSSCD) and the Stroke Prevention Trial in Sickle Cell Anemia (STOP). Patients who had experienced an overt stroke were excluded. MRI findings were classified as normal or "silent infarct." Results of TCD were classified as normal, conditional, or abnormal, based on the time-averaged maximum mean flow velocity in the proximal middle cerebral and distal internal carotid arteries.

RESULTS

Of 61 patients who had a normal MRI examination, 11 (18%) had either conditional (5 patients) or abnormal (6 patients) TCD results. Among 17 patients in whom silent infarction was seen on MRI, only 5 (29%) had a conditional (1 patient) or abnormal (4 patients) TCD velocity. Thus, discordant results were seen in 23 patients: 12 in which the TCD result was normal and the MRI abnormal; 11 in which the TCD velocity was elevated and the MRI normal.

CONCLUSIONS

Abnormal TCD and MRI examinations reveal different aspects of the pathophysiology of central nervous system (CNS) injury in sickle cell disease and are often discordant. Although TCD abnormality is predictive of overt stroke, the lack of concordance between TCD and MRI findings suggests a need to develop more sensitive and specific indicators of early CNS pathology, such as neuropsychometric testing and positron-emission tomography (PET) scans, and to obtain more information about microvascular pathologic processes that may affect CNS function.

Agkistin, a snake venom-derived glycoprotein Ib antagonist, disrupts von Willebrand factor-endothelial cell interaction and inhibits angiogenesis

Glycoprotein (GP) Ib, an adhesion receptor expressed on both platelets and endothelial cells, mediates the binding of von Willebrand factor (vWF). Platelet GPIb plays an important role in platelet adhesion and activation, whereas the interaction of vWF and endothelial GPIb is not fully understood. We report here that agkistin, a snake venom protein, selectively blocks the interaction of vWF with human endothelial GPIb and inhibits angiogenesis in vivo. Agkistin specifically blocked human umbilical vein endothelial cell (HUVEC) adhesion to immobilized vWF in a concentration-dependent manner. Fluorescein isothiocyanate (FITC)-conjugated agkistin bound to HUVECs in a saturable manner. AP1, a monoclonal antibody (mAb) raised against GPIb, specifically inhibited the binding of FITC-conjugated agkistin to HUVECs in a dose-dependent manner, but other anti-integrin mAbs raised against alpha(v)beta(3), alpha(2)beta(1), and alpha(5)beta(1) did not affect this binding reaction. However, neither agkistin (2 microgram/ml) nor AP1 (40 microgram/ml) apparently reduced HUVEC viability. Both agkistin and AP1 exhibited a profound anti-angiogenic effect in vivo when assayed by using the 10-day-old embryo chick chorioallantoic membrane model. These results suggest endothelial GPIb plays a role in spontaneous angiogenesis in vivo, and the anti-angiogenic effect of agkistin may be because of disruption of the interaction of endogenous vWF with endothelial GPIb.

Hydroxyurea therapy decreases the in vitro adhesion of sickle erythrocytes to thrombospondin and laminin

The adhesion of sickle erythrocytes to the vascular endothelium and subendothelial matrix probably contributes to the pathogenesis of vaso-occlusive disease. The chemotherapeutic agent hydroxyurea (HU) decreases the frequency of vaso-occlusive crises in patients with sickle cell disease. However, the exact mechanism(s) of HU's effect on vaso-occlusive crises is not fully understood. The goal of this study was to determine the effect of HU therapy on the adhesion of sickle erythrocytes to the subendothelial matrix proteins thrombospondin (TSP) and laminin under conditions of flow in vitro. Erythrocytes from patients with severe sickle cell disease on HU therapy (n = 14) had significantly less adhesion to TSP (687 +/- 92 erythrocytes/mm2, mean +/- SE) than untreated patients with severe disease (n = 18, 1176 +/- 117 erythrocytes/mm2, P = 0.003). In addition, there was significantly less adhesion of erythrocytes to immobilized laminin in patients treated with HU (1695 +/- 293 erythrocytes/mm2) than in the untreated patients (2590 +/- 296 erythrocytes/mm2, P = 0.02). Erythrocytes from an additional nine patients with severe sickle cell disease were studied both before and after initiation of HU therapy. Erythrocytes from these patients became less adhesive to both TSP (P = 0.001) and laminin (P = 0.01), a change that was sustained in most patients throughout the duration of the study (2 months to > 12 months). This study suggests that HU modulates the adhesive phenotype of sickle erythrocytes, an effect that may be in addition to, or independent of, other known effects of HU, such as an increase in fetal haemoglobin level.

An approach for enhancing heterologous production of Providencia rettgeri penicillin acylase in Escherichia coli

Heterologous production of Providencia rettgeri penicillin acylase (PAC) was optimized in Escherichia coli. Several factors, including carbon, temperature, and host effects, were identified to be critical for the enzyme overproduction. The optimum culture conditions for the enzyme production vary for different host/vector systems. With the optimization, both volumetric and specific PAC activities could be significantly improved by more than 50-fold compared to the native expression in P. rettgeri. The heterologous production could be possibly limited by translation or posttranslational steps, depending on the culture temperature and host/vector system. To our knowledge, this is the first evidence demonstrating the limiting step for the production of P. rettgeri PAC and the existence of the P. rettgeri PAC precursor.

Long-term survival of infants with idiopathic myelofibrosis

Idiopathic myelofibrosis can develop in children as well as adults. However, the disease appears to be much more aggressive in adults, being characterized by poor survival rates and a high frequency of malignant transformation. Here, we describe three cases of idiopathic myelofibrosis in infants, two of whom were followed for 16 and 22 years after diagnosis. Neither of these patients required more than minimal supportive care, and both have had spontaneous erythropoietic recovery as early as 2-3 years after diagnosis. There have been no indications of malignant transformation or clinical deterioration. Thus, idiopathic myelofibrosis may have a different pathogenesis and clinical course in infants from adults, requiring a more conservative approach to management.

Association of CTLA4 gene A-G polymorphism with type 1 diabetes in Chinese children

OBJECTIVE

The CTLA4 (cytotoxic T lymphocyte associated antigen-4) gene encodes the T cell receptor involved in the control of T cell proliferation and mediates T cell apoptosis. Thus it is a strong candidate gene for T cell-mediated autoimmune disease. There is polymorphism at position 49 in exon 1 of the CTLA4 gene, providing a A-G exchange. This polymorphism is reportedly associated with type 1 diabetes in Caucasians but not in a small data set of Chinese. We wished to test this polymorphism in a larger and more homogeneous data set of Chinese children with type 1 diabetes and normal adult controls.

DESIGN

A population-based case-control study of a CTLA4 gene 49 A-G polymorphism was performed to look for an association with type 1 diabetes in Chinese children.

PATIENTS

We analysed this polymorphism in 253 unrelated children (128 boys) with type 1 diabetes (age at diagnosis 7.1 +/- 3.7 years) and 91 randomly selected normal adults. All individuals were Han Chinese.

RESULTS

The genotype and gene frequencies of children with type 1 diabetes differed significantly from those of adult controls (P = 0.0091 and P = 0.0051, respectively). Genotype CTLA4 49 G/G and G allele conferred a risk of type 1 diabetes (RR = 2.13, 95% CI = 1.31-3.46, P = 0.0022; RR = 1.68, 95% CI = 1.17-2.43, P = 0.0051, respectively).

CONCLUSIONS

This study demonstrates that CTLA4 49 A-G polymorphism is associated with type 1 diabetes in Han Chinese children. The CTLA4 49 G allele confers an increased risk of type 1 diabetes.

Prediction of adverse outcomes in children with sickle cell disease

BACKGROUND

The ability to identify infants with sickle cell anemia who are likely to have severe complications later in life would permit accurate prognostication and tailoring of therapy to match disease-related risks and facilitate planning of clinical trials. We attempted to define the features of such babies by following the clinical course of 392 children with sickle cell disease from infancy to about the age of 10 years.

METHODS

We analyzed the records of 392 infants who received the diagnosis of homozygous sickle cell anemia or sickle cell-Beta(0)-thalassemia before the age of six months and for whom comprehensive clinical and laboratory data were recorded prospectively; data were available for a mean (+/-SD) of 10.0+/-4.8 years. Results obtained before the age of two years were evaluated to determine whether they predicted the outcome later in life.

RESULTS

Of the 392 infants in the cohort, 70 (18 percent) subsequently had an adverse outcome, defined as death (18 patients [26 percent]), stroke (25 [36 percent]) frequent pain (17 [24 percent]), or recurrent acute chest syndrome (10 [14 percent]). Using multivariate analysis, we found three statistically significant predictors of an adverse outcome: an episode of dactylitis before the age of one year (relative risk of an adverse outcome, 2.55; 95 percent confidence interval, 1.39 to 4.67), a hemoglobin level of less than 7 g per deciliter (relative risk, 2.47; 95 percent confidence interval, 1.14 to 5.33), and leukocytosis in the absence of infection (relative risk, 1.80; 95 percent confidence interval, 1.05 to 3.09).

CONCLUSIONS

Three easily identifiable manifestations of sickle cell disease that may appear in the first two years of life (dactylitis, severe anemia, and leukocytosis) can help to predict the possibility of severe sickle cell disease later in life.

Factorial modeling of differential distractor functioning in multiple-choice items

A factorial procedure for investigating differential distractor functioning in multiple-choice items is proposed. The procedure adopts the formulation of general linear models and treats grouping factors as independent variables and item parameters across the grouping factors as a dependent variable. Specifically, each distractor in a multiple-choice item is modeled with a distinct distractibility parameter. The distractibility parameters across groups are partitioned into a grand mean distractibility and sets of parameters representing main effects of the individual grouping factors, and interaction effects among them. Results of a simulation study show that the parameters of the proposed modeling were recovered very well. Ten four-choice items in the English test of the 1997 Taiwan Joint College Entrance Examination with seven thousands of examinees in two grouping factors were analyzed.

Fever-range hyperthermia stimulates alpha4beta7 integrin-dependent lymphocyte-endothelial adhesion

Migration of blood-borne lymphocytes into lymphoid tissues is initiated by the L-selectin and alpha4beta7 integrin adhesion molecules. Previous studies have shown that L-selectin adhesion is dynamically regulated by febrile temperatures. It is now reported that fever-range hyperthermia also acts directly on lymphocytes to enhance selected adhesive functions of alpha4beta7 integrin. Fever-range hyperthermia treatment in vitro (40 degrees C, 12 h) of murine TK1 lymphoma cells and human peripheral blood lymphocytes (PBL) stimulates alpha4beta7 integrin-dependent adhesion to high endothelial venules (HEV) in Peyer's patch and mesenteric lymph node frozen sections. TK1 cells are alpha4beta7hi L-selectin(lo), allowing for the analysis of alpha4beta7 integrin without contributions from L-selectin. Adhesion was further shown to involve alpha4beta7 integrin and its endothelial counter-receptor, mucosal addressin cell adhesion molecule-1 (MAdCAM-1) using function-blocking antibodies (i.e. DATK32, HP2/1, MECA-367). Fever-range hyperthermia also promotes alpha4beta7 integrin-mediated aggregation of TK1 cells. In sharp contrast, hyperthermia fails to increase alpha4beta7 integrin adhesion to fibronectin by TK1 cells. Expression of the alpha4beta7 heterodimer on TK1 cells or human PBL is not altered by hyperthermia, suggesting that hyperthermia stimulates adhesion by enhancing alpha4beta7 integrin avidity rather than its cell surface density. These results provide a mechanism whereby febrile temperatures during infection or clinical hyperthermia potentially amplify the immune response by stimulating L-selectin and alpha4beta7 integrin-dependent homing of immune effector cells to lymphoid tissues.

Heterogeneous Helicobacter pylori isolates from H. pylori-infected couples in Taiwan

Helicobacter pylori strain diversity was investigated in 55 H. pylori seropositive couples in Taiwan in biopsy samples from the antrum and corpus. Two DNA typing methods were used to characterize 90 isolates from 25 couples. In only 1 of the 25 couples was the same strain colonized from both partners. Comparison of isolates from 2 sites in each of 40 patients showed that 9 pairs were distinct but might be related. Peptic ulcer occurred in 77.8% of these 9 patients compared with 29% of 31 patients with the same predominant strain in 2 biopsies (P=.025). Random amplified polymorphic DNA and sequence analyses of 2 closely related isolates from 1 patient support the hypothesis that development of genetic diversity of H. pylori results from horizontal genetic exchange during long-term colonization of mixed bacterial populations.

Plastic microchip electrophoresis for analysis of PCR products of hepatitis C virus

BACKGROUND

Electrophoresis on polymeric rather than glass microstructures is a promising separation method for analytical chemistry. Assays on such devices need to be explored to allow assessment of their utility for the clinical laboratory.

METHODS

We compared capillary and plastic microchip electrophoresis for clinical post-PCR analysis of hepatitis C virus (HCV). For capillary electrophoresis (CE), we used a separation medium composed of 10 g/L hydroxypropyl methyl cellulose in Tris-borate-EDTA buffer and 10 micromol/L intercalating dye. For microchip electrophoresis, the HCV assay established on the fused silica tubing was transferred to the untreated polymethylmethacrylate microchip with minimum modifications.

RESULTS

CE resolved the 145-bp amplicon of HCV in 15 min. The confidence interval of the migration time was <3.2%. The same HCV amplicon was resolved by microchip electrophoresis in <1.5 min with the confidence interval of the migration time <1.3%.

CONCLUSION

The polymer microchip, with advantages that include fast processing time, simple operation, and disposable use, holds great potential for clinical analysis.

Novel strategy for efficient screening and construction of host/vector systems to overproduce penicillin acylase in Escherichia coli

A novel and simple method of using penicillin for screening of mutant strains with a high penicillin acylase (PAC) activity was developed. Random mutagenesis was conducted using a PAC-producing strain resistant to 6-aminopenicillanic acid (6-APA) as the parent strain and mutants were screened with penicillin at a high concentration. Results suggest that mutants with a high minimum inhibitory concentration for penicillin (MIC(penG)) usually overproduce PAC. Both volumetric and specific PAC activities of a mutant, MD7, were significantly higher than those of the parent strain, HBPAC101 harboring pCLL2902. The mutation(s) resulting in the enhanced expression was mapped on the host chromosome rather than the plasmid. In addition, the mutant strain of MDDeltaP7, derived by elimination of the harbored plasmid in MD7, was demonstrated to be efficient in production of PAC by using the expression plasmids for which expression of the pac gene is limited by translation. An extremely high specific PAC activity of more than 350 U/L/OD(600) was reached upon cultivation of MDDeltaP7 harboring pTrcKnPAC2902 in a bioreactor. As such, the strategy is effective in terms of constructing PAC overproducers and improving the process yield for production of PAC.

Refractory anemia with ringed sideroblasts in children: two diseases with a similar phenotype?

Three pediatric patients with refractory anemia with ringed sideroblasts (RARS) are presented. Bone marrow aspirates were examined using Romanowsky and Prussian blue iron stains in all three patients, and electron microscopic analysis was performed in one patient. All three patients had cytogenetic analysis of the bone marrow. Other studies included analysis of serum iron, total iron-binding capacity, ferritin, copper, vitamins B6 and B12, and folate levels. Antibody titers to Parvovirus, HIV, and other viruses were measured. The patients had contrasting clinical courses. Patients 1 and 2 had dysplastic hematopoietic features and cytogenetic findings (with either partial or one allele loss of chromosome 7), suggestive of myelodysplastic syndrome. Patient 1 experienced acute myeloid leukemia (AML) and had a good response to AML-directed therapy. Patient 2 had prolonged cytopenias and underwent bone marrow transplantation (BMT). Patient 3 had features suggestive of refractory anemia associated with mitochondrial cytopathy, including normal cytogenetics with pronounced vacuolization of marrow precursors. His anemia regressed spontaneously a few months after diagnosis. These patients represent two subgroups of pediatric RARS. Patients with the myelodysplastic syndrome (MDS) type may progress to cytopenias or leukemia and may require aggressive therapy; the type is characterized by clonal cytogenetic findings. The non-MDS type, which may relate to mitochondrial cytopathy, often shows spontaneous regression and requires only supportive treatment; it has normal cytogenetic findings.

The role of a conserved histidine residue, His324, in Trigonopsis variabilis D-amino acid oxidase

To investigate the functional role of an invariant histidine residue in Trigonopsis variabilis D-amino acid oxidase (DAAO), a set of mutant enzymes with replacement of the histidine residue at position 324 was constructed and their enzymatic properties were examined. Wild-type and mutant enzymes have been purified to homogeneity using the His-bound column and the molecular masses were determined to be 39.2 kDa. Western blot analysis revealed that the in vivo synthesized mutant enzymes are immuno-identical with that of the wild-type DAAO. The His324Asn and His324Gln mutants displayed comparable enzymatic activity to that of the wild-type enzyme, while the other mutant DAAOs showed markedly decreased or no detectable activity. The mutants, His324/Asn/Gln/Ala/Tyr/Glu, exhibited 38-181% increase in Km and a 2-10-fold reduction in kcat/Km. Based on the crystal structure of a homologous protein, pig kidney DAAO, it is suggested that His324 might play a structural role for proper catalytic function of T. variabilis DAAO.