A metal-chelating piezoelectric sensor chip for direct detection and oriented immobilization of polyHis-tagged proteins

A metal-chelating piezoelectric (PZ) chip for direct detection and controlled immobilization of polyHis-tagged proteins has been demonstrated. The chip was prepared by covalently binding a hydrogel matrix complex of oxidized dextran and nitrilotriacetic acid (NTA) ligand onto an activated alkanethiol-modified PZ crystal. The resulting chip effectively captured Ni2+ ions onto its NTA surface, as disclosed by the resonant frequency shift of the crystal and an X-ray photoelectron spectroscopy analysis. The real-time frequency analysis revealed that the bare NTA chip was nonfouling, regenerable, and highly reusable during continuous repetitive injections of ion solutions and binding proteins. In addition, the chip displayed good long-term reusability and storage stability. The individual binding studies of a polyHis-tagged glutathione-S-transferase and its native untagged form on various metal-charged chips revealed that Co2+, Cu2+, and Ni2+ ions each had different immobilization ability on the NTA surface, as well as their binding ability and selectivity with the tagged protein. As a result, the tagged protein immobilized on the Ni2+-charged chip can actively be bound with its antibody and substrate. Further, the quantitative analyses of the tagged protein in crude cell lysate with a single Ni2+-charged chip and of its substrate with a protein-coated chip were also successfully demonstrated. Therefore, this study initiates the possibilities of oriented, reversible, and universal immobilization of any polyHis-tagged protein and its functional study using a real-time PZ biosensor.

Metal ion reduction and resultant deposition on viologen-functionalized LDPE films and viologen-containing microporous membranes

Photo-induced reduction of gold and platinum metal salt solutions was carried out using viologen graft copolymerized on low-density polyethylene (LDPE) films and viologen-containing poly(vinylidene fluoride) (PVDF-PVBV) microporous membranes. The effects of the UV irradiation time and concentration of the metal salt solutions on the metal ion reduction process and the resultant metal deposition on the polymeric substrates were investigated. The metal-polymer composites were characterized using X-ray photoelectron spectroscopy (XPS), scanning and transmission electron microscopy (SEM and TEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and UV-visible absorption spectroscopy. The amount of metal uptake, the state of the metal, and the size of the metal particles were found to be strongly dependent on the UV irradiation time and the type and concentration of the metal salt solution. The microporous structure and the high viologen content of the PVDF-PVBV membrane constitute an effective matrix for metal ion reduction and preparation of metal nanoparticles.

Pleomorphic adenoma with extensive necrosis: report of two cases

Pleomorphic adenoma (PA) is the most common neoplasm for both the major and minor salivary glands. While PA is occasionally associated with cystic change or hemorrhage necrosis, spontaneous infarction appears to be very uncommon. We report two unusual cases of extensive necrosis of PA; one occurred in the palate with the necrotic tumor mass slipping into the oral cavity. This phenomenon, possibly associated with incision biopsy, has never been described previously. A second case, arising in the parotid with spontaneous tumor necrosis, poses some dilemma in differential diagnosis.

Reef-coral proteins as visual, non-destructive reporters for plant transformation

Recently, five novel fluorescent proteins have been isolated from non-bioluminescent species of reef-coral organisms and have been made available through ClonTech. They are AmCyan, AsRed, DsRed, ZsGreen and ZsYellow. These proteins are valuable as reporters for transformation because they do not require a substrate or external co-factor to emit fluorescence and can be tested in vivo without destruction of the tissue under study. We have evaluated them in a large range of plants, both monocots and dicots, and our results indicate that they are valuable reporting tools for transformation in a wide variety of crops. We report here their successful expression in wheat, maize, barley, rice, banana, onion, soybean, cotton, tobacco, potato and tomato. Transient expression could be observed as early as 24 h after DNA delivery in some cases, allowing for very clear visualization of individually transformed cells. Stable transgenic events were generated, using mannose, kanamycin or hygromycin selection. Transgenic plants were phenotypically normal, showing a wide range of fluorescence levels, and were fertile. Expression of AmCyan, ZsGreen and AsRed was visible in maize T1 seeds, allowing visual segregation to more than 99% accuracy. The excitation and emission wavelengths of some of these proteins are significantly different; the difference is enough for the simultaneous visualization of cells transformed with more than one of the fluorescent proteins. These proteins will become useful tools for transformation optimization and other studies. The wide variety of plants successfully tested demonstrates that these proteins will potentially find broad use in plant biology.

Development of a novel Agrobacterium-mediated transformation method to recover transgenic Brassica napus plants

We report here an in planta method to produce transgenic Brassica napus plants. The procedure included Agrobacterium-mediated inoculation of plants at various development stages along with a vacuum infiltration step. The flowering stage appeared to be the most receptive stage for transformation and production of transgenic plants. In some cases, the flowering stage was induced either by cold treatment or by high density planting. Molecular and genetic analysis revealed that single and multiple copy events were generated and that the transgenes were transmitted to the T1 and T2 progeny in a Mendelian fashion.

Motorcycle emissions and fuel consumption in urban and rural driving conditions

This work reports sampling of motorcycle on-road driving cycles in actual urban and rural environments and the development of representative driving cycles using the principle of least total variance in individual regions. Based on the representative driving cycles in individual regions, emission factors for carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NO(x)=NO+NO(2)) and carbon dioxide (CO(2)), as well as fuel consumption, were determined using a chassis dynamometer. The measurement results show that the representative driving cycles are almost identical in the three largest cities in Taiwan, but they differ significantly from the rural driving cycle. Irrespective of driving conditions, emission factors differ insignificantly between the urban and rural regions at a 95% confidence level. However, the fuel consumption in urban centers is approximately 30% higher than in the rural regions, with driving conditions in the former usually poor compared to the latter. Two-stroke motorcycles generally have considerably higher HC emissions and quite lower NO(x) emissions than those of four-stroke motorcycles. Comparisons with other studies suggest that factors such as road characteristics, traffic volume, vehicle type, driving conditions and driver behavior may affect motorcycle emission levels in real traffic situations.

Role of cytokines in photodynamic therapy-induced local and systemic inflammation

Photodynamic therapy (PDT) of tumour results in the rapid induction of an inflammatory response that is considered important for the activation of antitumour immunity, but may be detrimental if excessive. The response is characterised by the infiltration of leucocytes, predominantly neutrophils, into the treated tumour. Several preclinical studies have suggested that suppression of long-term tumour growth following PDT using Photofrin((R)) is dependent upon the presence of neutrophils. The inflammatory pathways leading to the PDT-induced neutrophil migration into the treated tumour are unknown. In the following study, we examined, in mice, the ability of PDT using the second-generation photosensitiser 2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a (HPPH) to induce proinflammatory cytokines and chemokines, as well as adhesion molecules, known to be involved in neutrophil migration. We also examined the role that these mediators play in PDT-induced neutrophil migration. Our studies show that HPPH-PDT induced neutrophil migration into the treated tumour, which was associated with a transient, local increase in the expression of the chemokines macrophage inflammatory protein (MIP)-2 and KC. A similar increase was detected in functional expression of adhesion molecules, that is, E-selectin and intracellular adhesion molecule (ICAM)-1, and both local and systemic expression of interleukin (IL)-6 was detected. The kinetics of neutrophil immigration mirrored those observed for the enhanced production of chemokines, IL-6 and adhesion molecules. Subsequent studies showed that PDT-induced neutrophil recruitment is dependent upon the presence of MIP-2 and E-selectin, but not on IL-6 or KC. These results demonstrate a PDT-induced inflammatory response similar to, but less severe than obtained with Photofrin((R)) PDT. They also lay the mechanistic groundwork for further ongoing studies that attempt to optimise PDT through the modulation of the critical inflammatory mediators.

Cytokine and adhesion molecule expression in primary human endothelial cells stimulated with fever-range hyperthermia

Migration of blood-borne lymphocytes into lymphoid tissues and sites of inflammation is initiated by vascular adhesion molecules and proinflammatory cytokines. Previous in vivo studies have shown that febrile temperatures dynamically stimulate adhesion in differentiated high endothelial venules (HEV), which are portals for lymphocyte extravasation. This report examines the direct effect of fever-range hyperthermia on the expression of adhesion molecules and cytokines by primary cultured endothelial cells. In both macrovascular (HUVEC) and microvascular (HMVEC) endothelial cells, fever-range hyperthermia (40 degrees C for 6-12 h) did not affect expression of adhesion molecules (ICAM-1, E-selectin, VCAM-1, P-selectin, PECAM-1, PNAd, MAdCAM-1), cytokine release (IL-1beta, TNF-alpha, IFN-gamma, IL-6, IL-11, IL-12, IL-13), or chemokine secretion (IL-8, RANTES, MCP-1, MIP-1beta, MIG). This is in contrast to the stimulatory effects of TNF-alpha or 43 degrees C heat shock. However, a novel role for fever-range hyperthermia was identified in augmenting actin polymerization in cultured endothelial cells and enhancing the ability of endothelial-derived factors to transactivate the alpha4beta7 integrin lymphocyte homing receptor. These findings provide insight into the tightly regulated effects of fever-range hyperthermia that exclude induction of adhesion in non-activated endothelium of normal blood vessels. Through these mechanisms, it is proposed that febrile temperatures associated with infection or clinical hyperthermia avoid the unproductive exodus of lymphocytes to non-involved extralymphoid tissues while simultaneously promoting lymphocyte delivery to sites of immune activation.

Modeling effects of differential item functioning in polytomous items

Conventional two-group DIF analysis for dichotomous items is extended to factorial DIF analysis for polytomous items where multiple grouping factors with multiple groups in each are jointly analyzed. By adopting the formulation of general linear models, item parameters across all possible groups are treated as a dependent variable and the grouping factors as independent variables. These item parameters are then reparameterized as a set of grand item parameters and sets of DIF parameters representing main and interaction effects of the factors on the items. Results of simulation studies show that the parameters of the proposed modeling could be satisfactorily recovered. A real data set of 10 polytomous items and 1924 subjects was analyzed. Applications and implications of the proposed modeling are addressed.

Measurement issues in screening outstanding teachers

Measurement issues that arise in a two-stage teacher evaluation for an outstanding faculty award are addressed. A teacher evaluation inventory with ten Likert-type items was developed. Thirty college teachers were rated by 293 students on the new inventory. The facet Rasch technique was applied to analyze the test data, and the items fit the Rasch models fairly well. The separation reliability for the teachers is.98, indicating that the items together with these students can differentiate the teachers extremely well. A cut score was set to.80 logits so that only those teachers with efficacy estimates above that level are eligible to apply for the award. A short version containing only half of the items was also developed.

Primary resistance to antibiotics and its clinical impact on the efficacy of Helicobacter pylori lansoprazole-based triple therapies

AIM

To evaluate Helicobacter pylori primary resistance and its clinical impact on the efficacy of two lansoprazole-based eradication triple therapies.

METHODS

H. pylori-positive patients (n=228) were randomized to receive one of the 1-week regimens: lansoprazole 30 mg, clarithromycin 500 mg and amoxicillin 1 g (LAC), or lansoprazole 30 mg, clarithromycin 500 mg and metronidazole 500 mg (LMC), each given twice daily. H. pylori status was assessed by 13C-urea breath test and culture at diagnosis and by 13C-urea breath test 6 weeks after therapy. Antibiotic susceptibility was determined by E-test (n=98).

RESULTS

The eradication rates with per protocol/ intention-to-treat analyses were: LAC (n=95/114) 83%/69% and LMC (n=96/114) 85%/72%. Primary resistance was 11% for clarithromycin, 41% for metronidazole and 0% for amoxicillin. Eradication in metronidazole-susceptible/-resistant strains was 85%/82% in LAC and 83%/63% in LMC. Significantly lower cure rates were observed in clarithromycin-resistant patients treated with LAC (95% vs. 0%, P < 0.001) and LMC (86% vs. 0%, P < 0.001).

CONCLUSIONS

One-week LAC and LMC are similarly effective therapies. Clarithromycin resistance significantly affected H. pylori eradication in both regimens.

[Experimental study of bovine bone morphogenetic protein combined with sintered bone in the treatment of bone defects]

OBJECTIVE

To confirm the capability of ectopic bone induction of the bovine bone morphogenetic protein (bBMP), and investigate the bBMP combined with sintered bone (SB) in the treatment of bone defects.

METHODS

bBMP was separated from the bovine cortical bone and implanted into the muscle pouches of the balb/c mouses. 4 mouses were killed at the 1st, 2nd, 3rd and 4th week, and their tissues were fixed in 4% formalin for histologic examination. The bBMP was combined with sintered bovine cancellons bone (SB), and segmental defects were made at raddi in 16 New Zealand rabbits. One side of the rabbits was implanted with bBMP-SB, and another side implanted with SB. The animals were killed in the 2nd, 4th, 6th and 8th week after operation for X-ray and histologic examination.

RESULTS

One week after bBMP implantation, the chondrocyte was induced in muscle pouches, the woven bone was seen in 2 weeks, and the trabecular bone was formed in 4 weeks. In bone defects models, the X-ray and histologic examination showed that all parameters (chondrocyte induction, the mount of the trabecular bone, defects heal) were better in the animals treated with bBMP-SB than that with SB.

CONCLUSION

1. bBMP can induce ectopic bone formation. 2. bBMP-SB can improve the healing of the bone defects.

A two-year pilot trial of hydroxyurea in very young children with sickle-cell anemia

OBJECTIVE

Hydroxyurea improves hematologic values and decreases vaso-occlusive complications in adults and children with sickle cell anemia (SCA), but has not been tested in infants before the onset of chronic organ dysfunction. We conducted a collaborative pilot trial of hydroxyurea in infants with SCA to assess its (1) feasibility of administration, (2) toxicity, (3) hematologic effects, and (4) effect on spleen function.

STUDY DESIGN

Patients with hemoglobin (Hb) SS or Sbeta(0) thalassemia (n = 28, median age 15 months) received hydroxyurea for 2 years at 20 mg/kg/day. Hydroxyurea was temporarily discontinued for predefined toxicity.

RESULTS

Seven patients exited the study early: five for noncompliance or refusal to continue, one for mild stroke, and one for fatal splenic sequestration. The predominant toxicity was transient neutropenia, which was usually associated with a viral-like illness. After 2 years of treatment, mean Hb level = 8.8 g/dL and Hb F = 20.3%, both higher than predicted age-specific levels. Radionuclide splenic uptake was absent in 47% of patients at study completion, compared with predicted functional asplenia in 80% of the patients.

CONCLUSIONS

Hydroxyurea therapy for infants with SCA is feasible and well tolerated, has hematologic efficacy, and may delay functional asplenia. The potential for hydroxyurea to preserve organ function in SCA should be further evaluated.

Two distinctive cell binding patterns by vacuolating toxin fused with glutathione S-transferase: one high-affinity m1-specific binding and the other lower-affinity binding for variant m forms

The Helicobacter pylori VacA causes large intracellular vacuoles in epithelial cells such as HeLa or RK13 cells. Two major VacA forms, m1 and m2, divergent in an approximately 300 amino acid segment within the cell binding domain P58, display distinct cell-type specificity. Sequence analysis of four vacA alleles showed that a m1-like allele (61) and two m2 alleles (62 and v226) mainly differed in the midregion and that v225, a m1m2 chimera, was a natural double crossover from v226 and another allele. Each of these alleles was expressed as a soluble GST-VacA fusion that did not form a large oligomer. The recombinant VacA portion nevertheless assembled into higher ordered structures and possessed biological binding activity similar to that of the native VacA. A direct comparison of fusion-cell binding activity showed that m1 > m1m2 > m2 in HeLa cells, whereas there were more similar activities in RK13 cells. Vacuolating analyses of three forms revealed a positive correlation between cell binding activity and vacuolating activity. Moreover, the m1-type N-terminal half portion of the midregion was crucial for HeLa cell cytotoxicity. Kinetic, Scatchard, and inhibition analyses suggested the presence of at least two receptors: a m1-type specific high-affinity receptor (K(d) = approximately 5 nM) and a common VacA receptor interacting similarly with m1, m1m2, and m2 via a lower affinity (K(d) = 45-67 nM). Expression of mainly the m1-type receptor on HeLa cells whereas both receptors on RK13 cells may account for distinct cell binding activity and therefore for cell-type specificity.

Silent infarction as a risk factor for overt stroke in children with sickle cell anemia: a report from the Cooperative Study of Sickle Cell Disease

OBJECTIVE

To determine whether children with homozygous sickle cell anemia (SCD) who have silent infarcts on magnetic resonance imaging (MRI) of the brain are at increased risk for overt stroke.

METHODS

We selected patients with homozygous SCD who (1) enrolled in the Cooperative Study of Sickle Cell Disease (CSSCD) before age 6 months, (2) had at least 1 study-mandated brain MRI at age 6 years or older, and (3) had no overt stroke before a first MRI. MRI results and clinical and laboratory parameters were tested as predictors of stroke.

RESULTS

Among 248 eligible patients, mean age at first MRI was 8.3 +/- 1.9 years, and mean follow-up after baseline MRI was 5.2 +/- 2.2 years. Five (8.1%) of 62 patients with silent infarct had strokes compared with 1 (0.5%) of 186 patients without prior silent infarct; incidence per 100 patient-years of follow-up was increased 14-fold (1.45 per 100 patient-years vs 0.11 per 100 patient-years, P =.006). Of several clinical and laboratory parameters examined, silent infarct was the strongest independent predictor of stroke (hazard ratio = 7.2, P =.027).

CONCLUSIONS

Silent infarct identified at age 6 years or older is associated with increased stroke risk.

Transthoracic and transesophageal echocardiographic diagnosis of aneurysm of the sinus of Valsalva: a review of five year experience

BACKGROUND

Aneurysms of the sinus of Valsalva (SVA) are uncommon congenital lesions. The clinical presentations vary from asymptomatic to progressive heart failure following rupture of the aneurysm into an adjacent cardiac chamber. Retrograde aortogram is the diagnostic tool of choice preoperatively. Recent studies have demonstrated that the SVA can be accurately diagnosed using transthoracic two-dimensional, and color Doppler flow mapping, even for surgical preparation without cardiac catheterization. We report our 5-year experience of transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) in the evaluation of SVA.

METHODS

Eleven adult patients with SVA with or without rupture were studied using both TTE and TEE. All of the diagnoses were subsequently comfirmed by either cardiac catheterization or surgical findings.

RESULTS

Aneurysms originated in the right coronary sinus (n = 9) and noncoronary sinus (n = 2); they ruptured into the right ventricle in 5 patients and the right atrium in 5 patients. An unruptured right SVA was noted in 1 patient. Both TTE and TEE could identify the site of the aneurysm, rupture sites, and the receiving chamber equally well. Co-existent cardiac lesions included 11 cases of valvular aortic regurgitation (mild in 7, moderate in 2 and severe in 2). Two cases of perimembranous type ventricular septal defect (VSD) and 6 cases of supracristal type VSD (including 1 case of tetraology of Fallot, 3 supracristal, 1 muscular and 1 subaortic) were noted. Three cases were complicated with valvular vegetations (1 aortic valve, 1 aortic and tricuspid valve and 1 aortic and pulmonic valve). One patient had patent ductus arteriosus and 2 patients had pulmonic valvular stenosis.

CONCLUSIONS

TEE provides clearer definition for the detailed anatomy of the ruptured sac and co-existent cardiac lesions than TTE through high resolution and closer approach. We conclude that TEE is a powerful complementary diagnostic tool in the evaluation of patients with SVA. TEE also provides additionally useful information for guiding the surgical approach and for assessing the operative results even without cardiac catheterization.

[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.