Plasma of patients with Upshaw-Schulman syndrome, a congenital deficiency of von Willebrand factor-cleaving protease activity, enhances the aggregation of normal platelets under high shear stress

Upshaw-Schulman syndrome (USS) is an autosomal recessive disorder characterized by repeated episodes of chronic thrombocytopenia and microangiopathic haemolytic anaemia (MAHA) that responds dramatically to infusions of fresh frozen plasma (FFP). Recent studies have provided consistent evidence that USS is a congenital deficiency of plasma von Willebrand factor-cleaving protease (VWF-CPase) activity and, therefore, unusually large VWF multimers (UL-VWFMs) are present in the plasma. However, the molecular mechanism of the clinical symptoms of USS is not well understood. We studied the relationship between UL-VWFMs and thrombocytopenia in two USS patients by analysing platelet aggregation using a mixture of the patient's plasma and normal washed platelets under high shear stress. Our results clearly showed a remarkably enhanced high shear stress-induced platelet aggregation (H-SIPA) by the patient's plasma. At 24 h after FFP infusion (approximately equal to 10 ml/kg body weight), the enhanced H-SIPA became almost completely normalized but, 2 d later, it began to return to the preinfusion level. These results were in accordance with the change in VWFM patterns. The specific effects of enhanced H-SIPA on VWF, platelet glycoprotein Ib and endogenous ADP released from platelets upon stimulation were confirmed using reagents that specifically inhibit their respective functions. Our present results clearly indicate that thrombocytopenia in USS patients is caused by a combination of the presence of UL-VWFMs, platelets and high shear stress generated in the microcirculation.

[Three-dimensional computed tomography angiography of coronary artery bypass graft with electron beam tomography]

OBJECTIVES

Assessment of coronary artery bypass graft patency by three-dimensional reconstructed computed tomography angiography (3D-CTA) derived from electrocardiography-gated contrast-enhanced electron beam tomography (EBT) was evaluated.

METHODS

Thirty-nine patients with 99 grafts (45 arterial grafts and 54 venous grafts) underwent 3D-CTA and selective coronary angiography within a 3-week interval. 3D-CTA images of the coronary bypass grafts were compared with the coronary angiography images used as the control.

RESULTS

3D-CTA defined 42 of 44 arterial grafts as patent (sensitivity: 95%), all 47 venous grafts as patent (sensitivity: 100%) and all 7 venous grafts as occlusive (specificity: 100%). The overall sensitivity and specificity were 98% and 88%, respectively.

CONCLUSIONS

3D-CTA is an useful noninvasive technique with adequate sensitivity and specificity to assess coronary artery bypass graft patency.

Association of amino acid substitutions in penicillin-binding protein 3 with beta-lactam resistance in beta-lactamase-negative ampicillin-resistant Haemophilus influenzae

The affinity of [(3)H]benzylpenicillin for penicillin-binding protein (PBP) 3A was reduced in 25 clinical isolates of beta-lactamase-negative ampicillin (AMP)-resistant (BLNAR) Haemophilus influenzae for which the AMP MIC was > or =1.0 microg/ml. The affinities of PBP 3B and PBP 4 were also reduced in some strains. The sequences of the ftsI gene encoding the transpeptidase domain of PBP 3A and/or PBP 3B and of the dacB gene encoding PBP 4 were determined for these strains and compared to those of AMP-susceptible Rd strains. The BLNAR strains were classified into three groups on the basis of deduced amino acid substitutions in the ftsI gene, which is thought to be involved in septal peptidoglycan synthesis. His-517, near the conserved Lys-Thr-Gly (KTG) motif, was substituted for Arg-517 in group I strains (n = 9), and Lys-526 was substituted for Asn-526 in group II strains (n = 12). In group III strains (n = 4), three residues (Met-377, Ser-385, and Leu-389), positioned near the conserved Ser-Ser-Asn (SSN) motif, were replaced with Ile, Thr, and Phe, respectively, in addition to the replacement with Lys-526. The MICs of cephem antibiotics with relatively high affinities for PBP 3A and PBP 3B were higher than those of AMP and meropenem for group III strains. The MICs of beta-lactams for H. influenzae transformants into which the ftsI gene from BLNAR strains was introduced were as high as those for the donors, and PBP 3A and PBP 3B showed decreased affinities for beta-lactams. There was no clear relationship between 7-bp deletions in the dacB gene and AMP susceptibility. Even though mutations in another gene(s) may be involved in beta-lactam resistance, these data indicate that mutations in the ftsI gene are the most important for development of resistance to beta-lactams in BLNAR strains.

A 13C-urea breath test in children with helicobacter pylori infection: assessment of eradication therapy and follow-up after treatment

PURPOSE

Our aim was to evaluate the usefulness of the 13C-urea breath test (UBT) for the diagnosis of Helicobacter pylori infection, for assessment of the efficacy of eradication therapy, and for post-treatment follow-up in children.

METHODS

Seventy-two patients who underwent endoscopy for symptoms related to the upper gastrointestinal tract were examined by rapid urease test, histology, and culture. The patients were also studied with serology and UBT.

RESULTS

Forty-seven of the 72 patients were diagnosed with H. pylori infection, based on the results of biopsy-based tests and serology. As an initial diagnostic test to detect H. pylori infection, the sensitivity of the UBT was 95%, which was comparable with that of histology (94%), rapid urease test (96%), and serology (91%) and was greater than that of culture (79%). The specificity of the UBT was 100%, which was comparable with that of the other four tests. The efficacy of eradication therapy was assessed by biopsy-based tests and the UBT in 24 H. pylori-positive patients. For this purpose, the sensitivities of UBT and histology were 100%, while the sensitivities of culture and the rapid urease test were 88%. The specificity was 100% for all of these tests. Eleven patients were assessed by biopsy-based tests and UBT after more than 6 months of post-treatment follow-up. There were no discordances between the results of the UBT and those of the biopsy-based tests in any of the patients.

CONCLUSIONS

The UBT may be useful for detecting H. pylori infection in children with upper gastrointestinal tract symptoms, for assessment of the efficacy of eradication therapy, and for the follow-up evaluation of patients after the therapy.

In situ high resolution electron microscopy/electron energy loss spectroscopy observation of wetting of a Si surface by molten Al

Electron energy loss spectroscopy was used to observe the segregation of Al on a Si surface above the melting point of Al. A mixture of Al and Si particles was heated above the melting point of Al in a vacuum of 1 x 10(-5) Pa. The Si surface, which initially had been covered with an amorphous oxide layer before heating, became clean and atomically facetted when the Al melted. It was shown that the Si surface was segregated with Al.

Upshaw-Schulman syndrome revisited: a concept of congenital thrombotic thrombocytopenic purpura

Upshaw-Schulman syndrome (USS) is a congenital bleeding disorder characterized by repeated episodes of thrombocytopenia and microangiopathic hemolytic anemia that respond to infusions of fresh frozen plasma. Inheritance of USS has been thought to be autosomal recessive, because 2 siblings in the same family are often affected but their parents are asymptomatic. Recently, chronic relapsing thrombotic thrombocytopenic purpura (CR-TTP), reported almost exclusively in adults, was shown to be caused by inherited or acquired deficiency in the activity of a plasma von Willebrand factor-cleaving protease (vWF-CPase). The pathogenesis of USS is unknown, and a relationship between CR-YEP and USS has not been reported. We studied 3 unrelated USS patients (ST, SY, and KI) who presented with severe indirect neonatal hyperbilirubinemia. All 3 patients had undetectable vWF-CPase activity, and the inhibitors to vWF-CPase were all negative. In their parents with no clinical symptoms, vWF-CPase activities as a percentage of control samples (mother/father) were 17/20 for ST, 60/45 for SY, and 36/5.6 for KI. Thus, USS and vWF-CPase activity appear to be coinherited as autosomal recessive traits. Transfusion of fresh frozen plasma in 2 patients (ST and SY) resulted in the expected maximal increment of approximately 7% to 8% in vWF-CPase activity at 1 to 4 hours, but the levels became less than 3% within 2 days. After this decrease, platelet counts increased, plateaued in the normal range at 10 to 12 days, and declined thereafter. Thus, the 2 to 3 weeks of therapeutic benefit from plasma infusions will be discussed in relation to the intravascular lifetime of vWF-CPase.

Dynamic chemical mapping near a Si/SiO2 interface at elevated temperatures using plasmon-loss images

Plasmon-loss imaging was applied to chemical mapping during an in-situ heating experiment. The technique was applied to observation of vibration of a Si/SiO2 interface which took place during reduction of SiO2 at high temperature. The chemical maps of Si and SiO2 were recorded dynamically using a conventional TV-VTR system at a time resolution of 1/30 s.

Urine-based enzyme-linked immunosorbent assay for the detection of Helicobacter pylori infection in children

OBJECTIVE

Serology and (13)C-urea breath test have been widely used as noninvasive tests to detect Helicobacter pylori infection. However, easier collection of samples and lower costs are desirable for diagnosis of the individual patient or for use in epidemiologic studies. Our aim was to study the diagnostic accuracy of a recently developed urine-based enzyme-linked immunosorbent assay (ELISA) kit for the detection of H pylori-specific immunoglobulin G (IgG) antibodies in children.

STUDY DESIGN

Specimens of serum and randomly voided urine were collected from 816 children (0-15 years old) and were analyzed using 2 serum-based ELISA kits and a urine-based ELISA kit, respectively. Based on results of serology, the sensitivity, specificity, and accuracy of the urine-based ELISA kit were evaluated. With regard to false-positive and false-negative results, urinary IgG concentrations and IgG/creatinine levels were studied.

RESULTS

Both serum-based ELISAs were positive in 41 children and were negative in 666, who were enrolled in this study. The remaining 109 children were excluded because of disagreement between the results of the 2 serum-based ELISAs, including indeterminate values. Overall sensitivity, specificity, and accuracy of urine-based ELISA test compared with serology were 85.4%, 95.5%, and 94.9%, respectively. On positivity rates, the urine-based ELISA was closely coincident with the serum-based ELISA in each age group. There was no correlation between antibody levels detected by urine-based ELISA and each serum-based ELISA. Urinary IgG concentrations and IgG/creatinine levels were significantly higher in false-positives and were lower in false-negatives than in true-positives plus true-negatives for serology. Most of those with false-positive results had trace to moderate proteinuria.

CONCLUSIONS

The urine-based ELISA is an alternative to serum-based ELISA for diagnosis of H pylori infection in children and should be suitable for large-scale epidemiologic studies concerning the organism. In children with proteinuria, results of the test should be interpreted with caution. It is possible that the urine-based ELISA method would be applicable to diagnosis of other infectious diseases.

Allelotype analysis of gallbladder carcinoma associated with anomalous junction of pancreaticobiliary duct

Anomalous junction of pancreaticobiliary duct (AJPBD) patients has an increased risk of gallbladder and bile duct carcinomas. However, the relevance of carcinoma with AJPBD is not fully clarified. We performed analysis of loss of heterozygosity (LOH) at p53 locus and immunohistochemistry of p53 and K-ras gene mutation in five cases of gallbladder carcinoma associated with AJPBD. LOH of p53 locus and overexpression of p53 were detected in two out of five (40%) and five out of five (100%), respectively, in the present study. K-ras gene mutation at codon 12 and 13 was not detected (0%, 0/5). These results suggest that aberrations of p53 are involved in carcinogenesis of gallbladder carcinoma associated with AJPBD. Next, in order to find the genetic events besides K-ras mutation and overexpression of mutant p53 in this disease, LOH analysis was performed using 72 microsatellite markers. High frequency of allelic loss (> 50%) was found on 2p (81.8%), 4p (50%), 4q (50%), 8q (60%), 9q (50%), 10p (50%), 14p (60%), 14q (50%), 16p (60%), 19p (50%), 21p (50%) and Xp (66.6%). The highest deletion regions on chromosome 2p24 (3/3, 100%), 14q22 (3/4, 75%) and 21q22 (3/4, 75%) were found. The present study suggests that gallbladder carcinoma associated with AJPBD has high frequent allelic loss and has two new regions which may harbor putative tumor suppressor genes.

Quantitative analysis of regional wall motion and thickening by quantitative gated SPECT: comparison with visual analysis

PURPOSE

Electrocardiograph-gated myocardial SPECT permits a quantitative assessment of global and regional functions by quantitative gated SPECT software. To validate quantitative indexes of wall motion and wall thickening, the authors compared these indexes with visual scores.

MATERIALS AND METHODS

Gated myocardial SPECT was performed 60 minutes after the administration of Tc-99m sestamibi at rest in 42 patients with coronary artery disease. Regional wall motion (measured in millimeters and wall thickening (expressed as a percentage) were calculated by quantitative gated SPECT software in nine left ventricular myocardial segments and the results were compared with the five-point visual score interpretations of cinematic display.

RESULTS

A high correlation of wall motion was observed between the quantitative and visual analyses (r = 0.810; P < 0.001). In addition, a high but somewhat less significant correlation of wall thickening was observed between the quantitative and visual analyses (r = 0.606; P < 0.001).

CONCLUSIONS

In conclusion, regional wall motion and wall thickening can be evaluated quantitatively by electrocardiograph-gated myocardial SPECT and quantitative gated SPECT software. This will be useful for functional assessments made with various interventions.

A Generalized Model for Describing Particle Formation in the Synthesis of Monodisperse Oxide Particles Based on the Hydrolysis and Condensation of Tetraethyl Orthosilicate

A generalized model considering reaction and diffusion processes as rate determining steps is proposed for the formation of particles from hydrolysis and condensation of tetraethyl orthosilicate (TEOS). Reaction rate constant is assumed to be proportional to contact-surface area of two particles. Diffusion rate constant is given by Fuchs' stability theory with interparticle potential containing van der Waals attraction and electrostatic repulsion. To examine the validity of the model, ammonia-catalyzed reactions of TEOS were carried out in an ethanol-water solution at a water concentration of 11 mol/dm(3), an ammonia concentration of 1.0 mol/dm(3), and TEOS concentrations of 0.2 and 0.4 mol/dm(3) in the presence and in the absence of electrolytes. The experiments included competitive particle growth and seeded and nonseeded reactions. The model quantitatively expressed the results of the competitive growth experiments in which particles with different sizes grew at the same rate. The model gave the expected trend for the effect of ionic strength on particle sizes in the nonseeded reaction and the suppression of secondary particles in the seeded reaction by the addition of an electrolyte KCl. Good estimation was also obtained for transient particle size distributions in the nonseeded reaction and the seeded reaction in which secondary particles were generated. Copyright 2000 Academic Press.

A new dynamic myocardial phantom for the assessment of left ventricular function by gated single-photon emission tomography

Gated myocardial perfusion single-photon emission tomography (SPET) has been used for the measurement of left ventricular (LV) function and validated by means of comparison with other imaging modalities. We have designed a new dynamic myocardial phantom in order to validate the LV function as assessed by the use of gated myocardial perfusion SPET. The phantom consists of two half-ellipsoids (an endocardial surface and an epicardial surface) and a thorax. The myocardial space is filled with a radioactive solution. The endocardial surface moves continuously towards and away from the epicardial surface in the longitudinal axis to vary the LV volume [143 ml at end-diastole (ED), 107 ml at end-systole (ES)] and thickness (apex 8 mm at ED and 26 mm at ES, midplane 8 mm). The mean values of wall motion (WM) for the apical midplane region and the basal midplane region were 5 mm and 2 mm, respectively. Gated myocardial SPET was performed during 8 and 16 intervals. These projection data sets were processed using a Butterworth filter with an order of 5 and a critical frequency of 0.34 cycles/cm. LV function was calculated using the quantitative gated SPET (QGS) algorithm. The LV function values estimated by gated SPET during 16 intervals [22% for ejection fraction (EF), 3.7 mm for WM of the apical midplane, 1.7 mm for WM of the basal midplane] closely resembled actual LV functions [25% for EF, 5 mm for WM of the apical midplane, 2 mm for WM of the basal midplane]. However, the estimated values during 8 intervals were smaller than those during 16 intervals (19% for EF, 3.3 mm for WM of the apical-midplane, 1.1 mm for WM of the basal-midplane). The estimated LV volumes closely correlated with the actual volumes (r=0.99 for 16 intervals, r=0.95 for 8 intervals). Utilizing this phantom, LV function estimated using gated myocardial SPET can be compared with actual values.

A Simple Method for Producing Micrometer-Sized Monodisperse Polystyrene Particles in Aqueous Media

A method was developed for producing micrometer-sized, highly monodisperse polystyrene particles in single stage polymerization in aqueous media. The method employs an amphoteric surfactant, dimethyldodecylbetaine, that is added to the reaction system of styrene/K(2)S(2)O(8)/water in early stage of reaction. Polymerizations were carried out over a range of initiator concentrations (4-8 mmol/dm(3) H(2)O). The polymerization procedure could produce particles with an average diameter of 3.4 µm with a coefficient of variation of particle size distribution of 4.0%. Copyright 2000 Academic Press.

Prevalence and clinical characteristics of patients with atrial fibrillation: analysis of 20,000 cases in Japan

In Japan, data on the epidemiological and clinical features of atrial fibrillation (AF) are rather sparse; even less data are available on the risk of thromboembolism in nonvalvular AF. The present study enrolled 19,825 patients who visited the cardiovascular clinics of the 13 hospitals in Hokkaido, Japan, between March and July 1995. The prevalence of AF, the clinical characteristics of AF patients, and the occurrence of ischemic events were examined during the 2 year follow-up period. The prevalence of AF increased with age, and the overall prevalence was 14%. Antithrombotic therapy was used in 57% of AF patients and the incidence of ischemic events during the follow-up period was 4.6% in all AF patients. Warfarin reduced the risk of ischemic events in both the valvular and nonvalvular AF groups. A history of cerebrovascular accidents, advanced age, and the presence of underlying heart disease were each associated with a significantly increased risk of ischemic events in the nonvalvular AF group. These results show a lower incidence of ischemic events and more frequent use of antiplatelet drugs in the nonvalvular AF group. Further prospective studies are needed to determine the best preventive methods for thromboembolic complications in Japanese patients with nonvalvular AF.

[Comparison between leucyl aminopeptidase and pseudo leucine aminopeptidase activities in sera]

The highest activities of leucyl aminopeptidase(LAP, cytosol aminopeptidase, EC 3.4.11.1) in sera have been found in patients with acute hepatitis(Kanno et al., Am J Clin Path, 82: 700-705, 1984). I observed inpatients with very high activities of LAP and alcohol dehydrogenase(AD) in sera. However, only slight elevations of serum pseudo leucine aminopeptidase(PLA), that is, membrane alanyl aminopeptidase(MAA, microsomal aminopeptidase, EC 3.4.11.2) activities for hydrolysis of leucyl-4-nitroanilide were observed in these patients. They were patients in critical care unit with ischemia caused by a cardiopulmonary arrest, multiple trauma, acute myocardial infarction or operation. Therefore, we should measure LAP activities in sera rather than PLA(MAA) activities in these patients.

Comparison between segmental wall motion and wall thickening in patients with coronary artery disease using quantitative gated SPECT software

This study was performed to evaluate regional wall motion (WM) and wall thickening (WT) using gated myocardial perfusion single photon emission computed tomography (SPECT) and to determine their similarity and disparity in patients with coronary artery disease (CAD). A total of 44 patients underwent 1 day stress/rest (MIBI) gated SPECT. Commercially available quantitative analysis of gated SPECT (QGS) software was used to generate 3D surface display and cine-mode SPECT display. Left ventricle was divided into nine segments to score WM and WT from 0 (no abnormality) to 4 (severe abnormality) by six independent observers. Finally a mean score was calculated for each segment from the scores of six observers. There was fairly good correlation between WM and WT of individual segments (r = 0.62, p < 0.0001). Concordance rate (IWM - WTI < 1) was 85%. A large difference between WM and WT (WM - WT > or = 2) was observed in 15 segments, including 12 segments with greater WM abnormalities and 3 segments with greater WT abnormalities (lateral and inferior walls). Greater WM abnormalities were most commonly observed in anteroseptal segments especially in post coronary artery bypass grafting (CABG) patients. In conclusion, WM and WT showed similarity on QGS studies. However, these two parameters may be determined separately in gated SPECT studies for comprehensive and robust evaluation of the functional status of myocardium. Analyses based on WM assessment alone may lead to erroneous results especially in septal regions.

Iron-deficiency anemia associated with Helicobacter pylori gastritis

BACKGROUND

Recent studies have suggested an association of Helicobacter pylori and iron-deficiency anemia (IDA). This is a report of six cases of IDA associated with H. pylori gastritis.

METHODS

Six patients with IDA were studied (5 boys and 1 girl; mean age 13.6 years; range 13-15 years). Five had a medical history of long-standing IDA and of oral iron supplementation at outpatient clinics. The anemia recurred after the iron therapy had been discontinued. The sixth patient was admitted to the hospital with severe IDA. An extensive work-up was ordered that included technetium-99m (99mTc) scans for Meckel's diverticulum, total colonoscopy, and gastrointestinal endoscopy. After biopsy-based H. pylori test results were confirmed to be positive, anti-H. pylori therapy consisting of lansoprazole, clarithromycin, and metronidazole was administered for 2 weeks with no iron supplementation. The hematologic profile and iron status were assessed periodically after the end of the eradication regimen.

RESULTS

Upper gastrointestinal endoscopy revealed a marked antral nodularity but no evidence of bleeding lesions in all the patients. Given the histology and the fact that rapid urease test results were positive, chronic active gastritis with H. pylori was diagnosed in all these cases. H. pylori was successfully eradicated in all the patients. There was no evidence of IDA in any of the follow-up examinations between 27 and 50 months after anti-H. pylori therapy.

CONCLUSIONS

H. pylori infection may be involved in cases of IDA of unknown origin, and the eradication of H. pylori can be associated with the resolution of anemia.

Heterogeneity of myocardial wall motion and thickening in the left ventricle evaluated with quantitative gated SPECT

BACKGROUND

Global and regional ventricular function may be evaluated by using gated myocardial perfusion single photon emission computed tomography (SPECT). This study investigated two parameters of regional contraction of the left ventricle, segmental wall motion (WM) and wall thickening (WT), to determine their similarity and disparity in each myocardial segment in patients with normal myocardial perfusion.

METHODS AND RESULTS

Thirty-five patients with normal myocardial perfusion and cardiac function (mean left ventricular ejection fraction, 62.6%+/-8.8%) were included in this study. A 1-day stress/rest protocol was used as a means of acquiring technetium 99m (Tc-99m) sestamibi gated SPECT protocol for each patient. A commercially available software package for quantitative gated SPECT (QGS) was used to generate cine loop three-dimensional surface display and SPECT images. The left ventricle was divided into 9 segments to score WM and WT (on a scale of 0 to 4, with 0 being normal and 4 being severely reduced) by 6 independent observers. The WM score was significantly higher than the WT score in the septum, whereas the WM score was lower than the WT score in the inferior segment. Similar WM and WT scores were observed in the remaining segments.

CONCLUSIONS

Heterogeneous myocardial WM and WT were observed by using QGS software. These findings suggest that different criteria are required in each segment to evaluate segmental WM and WT by means of gated myocardial perfusion SPECT.

The 2.0 A crystal structure of Thermus thermophilus methionyl-tRNA synthetase reveals two RNA-binding modules

BACKGROUND

The 20 aminoacyl-tRNA synthetases are divided into two classes, I and II. The 10 class I synthetases are considered to have in common the catalytic domain structure based on the Rossmann fold, which is totally different from the class II catalytic domain structure. The class I synthetases are further divided into three subclasses, a, b and c, according to sequence homology. No conserved structural features for tRNA recognition by class I synthetases have been established.

RESULTS

We determined the crystal structure of the class Ia methionyl-tRNA synthetase (MetRS) at 2.0 A resolution, using MetRS from an extreme thermophile, Thermus thermophilus HB8. The T. thermophilus MetRS structure is in full agreement with the biochemical and genetic data from Escherichia coli MetRS. The conserved 'anticodon-binding' residues are spatially clustered on an alpha-helix-bundle domain. The Rossmann-fold and anticodon-binding domains are connected by a beta-alpha-alpha-beta-alpha topology ('SC fold') domain that contains the class I specific KMSKS motif.

CONCLUSIONS

The alpha-helix-bundle domain identified in the MetRS structure is the signature of the class Ia enzymes, as it was also identified in the class Ia structures of the isoleucyl- and arginyl-tRNA synthetases. The beta-alpha-alpha-beta-alpha topology domain, which can now be identified in all known structures of the class Ia and Ib synthetases, is likely to dock with the inner side of the L-shaped tRNA, thereby positioning the anticodon stem.

Management of severe neutropenia with cyclosporin during initial treatment of Epstein-Barr virus-related hemophagocytic lymphohistiocytosis

Severe neutropenia (absolute neutrophil count <500/gl) is probably due to the combined effects of dysregulated cytokine production and chemotherapeutic agents, and is one of the risk factors in the initial treatment of patients with Epstein-Barr virus-related hemophagocytic lymphohistiocytosis (EBV-HLH). We report here 9 cases of neutropenic HLH, of which 8 were treated with cyclosporin (CSA, 2-6 mg/kg/day; continuous infusion, or 6 mg/kg/day; per os, for periods ranging from 9 days to >8 weeks) in the initial neutropenic phase during induction treatment using corticosteroids and etoposide. Five of the 6 cases, in which CSA treatment was started early (before the second week of induction), survived the critical period with recovery of neutrophil counts within a week. The remaining 3 cases, in which CSA was introduced later or not at all, died of infection. Based on these results, we recommend a prompt short-term CSA infusion during neutropenic episodes in the most common treatment regimen of etoposide and corticosteroids in patients with HLH. Improved neutrophil recovery as a result of CSA treatment makes it possible to continue immunochemotherapy safely and obtain improved patient outcomes.

Crystal structure of Escherichia coli methionyl-tRNA synthetase highlights species-specific features

The 3D structure of monomeric C-truncated Escherichia coli methionyl-tRNA synthetase, a class 1 aminoacyl-tRNA synthetase, has been solved at 2.0 A resolution. Remarkably, the polypeptide connecting the two halves of the Rossmann fold exposes two identical knuckles related by a 2-fold axis but with zinc in the distal knuckle only. Examination of available MetRS orthologs reveals four classes according to the number and zinc content of the putative knuckles. Extreme cases are exemplified by the MetRS of eucaryotic or archaeal origin, where two knuckles and two metal ions are expected, and by the mitochondrial enzymes, which are predicted to have one knuckle without metal ion.