Valley polarization assisted spin polarization in two dimensions

Valleytronics is rapidly emerging as an exciting area of basic and applied research. In two-dimensional systems, valley polarization can dramatically modify physical properties through electron-electron interactions as demonstrated by such phenomena as the fractional quantum Hall effect and the metal-insulator transition. Here, we address the electrons' spin alignment in a magnetic field in silicon-on-insulator quantum wells under valley polarization. In stark contrast to expectations from a non-interacting model, we show experimentally that less magnetic field can be required to fully spin polarize a valley-polarized system than a valley-degenerate one. Furthermore, we show that these observations are quantitatively described by parameter-free ab initio quantum Monte Carlo simulations. We interpret the results as a manifestation of the greater stability of the spin- and valley-degenerate system against ferromagnetic instability and Wigner crystalization, which in turn suggests the existence of a new strongly correlated electron liquid at low electron densities.

Metallic behaviour in SOI quantum wells with strong intervalley scattering

The fundamental properties of valleys are recently attracting growing attention due to electrons in new and topical materials possessing this degree-of-freedom and recent proposals for valleytronics devices. In silicon MOSFETs, the interest has a longer history since the valley degree of freedom had been identified as a key parameter in the observation of the controversial "metallic behaviour" in two dimensions. However, while it has been recently demonstrated that lifting valley degeneracy can destroy the metallic behaviour, little is known about the role of intervalley scattering. Here, we show that the metallic behaviour can be observed in the presence of strong intervalley scattering in silicon on insulator (SOI) quantum wells. Analysis of the conductivity in terms of quantum corrections reveals that interactions are much stronger in SOI than in conventional MOSFETs, leading to the metallic behaviour despite the strong intervalley scattering.

[Does the bilateral internal thoracic artery harvesting increase wound infection?]

The aim of this study is to compare the frequency of wound infection between bilateral and single internal thoracic artery (ITA) harvesting in coronary artery bypass grafting (CABG) cases. Two hundreds and thirty-four consecutive CABG cases performed harvesting either bilateral ITA (BITA) or single ITA (SITA) from January 2004 to December 2008, with or without concomitant surgery were studied. Harmonic Scalpel was used for the harvesting with skeletonization technique. The cases were divided into 2 groups: BITA group (n = 180) and SITA group (n = 54). The frequencies of wound infection were 3.7% in SITA group and 6.1% in BITA group. As to deep sternal infection, they were 1.9% in SITA group and 1.1% in BITA group. There was no significant difference between the 2 groups. Multivariate analysis of all patients showed that emergency cases, hypertension, congestive heart failure, and reopening for bleeding were identified as independent risk factors for wound infection. There were 113 diabetes mellitus (DM) patients out of all patients ; SITA group (n = 22) and BITA group (n = 91). Their wound infection rates were 4.5% and 6.6%, and those of deep sternal infection were 0% and 2.2%, respectively. There was no significant difference between them. In conclusion, BITA harvesting with skeletonized technique may be used as safely as SITA harvesting even in DM patients.

Impact of valley polarization on the resistivity in two dimensions

We examine the temperature dependence of resistivity in a two-dimensional electron system formed in a silicon-on-insulator quantum well. The device allows us to tune the valley splitting continuously in addition to the electron density. Our data provide a global picture of how the resistivity and its temperature dependence change with valley polarization. At the boundary between valley-polarized and partially polarized regions, we demonstrate that there is an insulating contribution from spin-degenerate electrons occupying the upper valley-subband edge.

Changes in cerebral oxygenation in children undergoing surgical repair of ventricular septal defects

There have been few published studies on changes in cerebral oxygenation during paediatric cardiac surgery as measured by conventional near-infrared spectroscopy. We studied changes in cerebral oxygenation in 16 children undergoing surgical repair of ventricular septal defects. Fifteen of the patients showed similar patterns of changes: brain tissue concentrations of oxyhaemoglobin decreased significantly during cardiopulmonary bypass, whereas there was no significant change in brain tissue concentrations of deoxyhaemoglobin. In the remaining patient, who suffered decreased blood flow to the lower body during surgery, the pattern of changes was different to that of the other subjects. This patient suffered postoperative respiratory and renal failure. This study suggests that conventional near-infrared spectroscopy may be useful for clinical monitoring during ventricular septal defect repair.

Age-related changes in the cerebral distribution of 99mTc-ECD from infancy to adulthood

Although cerebral blood flow in infants differs from that in older individuals, the distribution of 99mTc-ethyl cysteinate dimer (ECD) in infants has not been well studied. This study compared 99mTc-ECD distribution in infants and children with that in young adults.

METHODS

99mTc-ECD SPECT was performed on 37 patients suspected of having epilepsy, ranging in age from 3 mo to 26 y. The patients were divided into two age-matched groups, a drug-free group (n = 19) and a drug-taking group (n = 18), according to their anticonvulsant medication status at the time of examination. 99mTc-ECD (100-740 MBq) was injected interictally, and SPECT data were acquired using a triple-head gamma camera. Mean whole-brain counts were obtained from 10 sequential SPECT images. Regions of interest were set bilaterally on five areas of the cerebral cortex and on the basal ganglia, thalamus and cerebellum. The brain perfusion index (BPI) was obtained as a ratio of the mean counts in each region of interest to the mean whole-brain counts. The relationship between BPI and age in each region in the drug-free and drug-taking groups was analyzed separately and together using linear regression. The relationship between five patient age groups (<1 y, n = 4; 1-4 y, n = 9; 5-9 y, n = 8; 10-15 y, n = 7; >15 y, n = 9) and BPI in each region was also examined using multiple comparison analyses.

RESULTS

Significant positive correlations between BPI and age in the frontal cortex and cerebellum were confirmed in the drug-free group. Anticonvulsant drugs did not affect the regression lines of BPI in the frontal cortex and cerebellum. Significant differences in BPI between age groups were seen in the parietal cortex, frontal cortex, occipital cortex, basal ganglia, thalamus and cerebellum in all patients.

CONCLUSION

Age-related changes in cerebral 99mTc-ECD distribution were confirmed and found to be unaffected by the administration of anticonvulsant drugs. 99mTc-ECD uptake in children and infants is different from cerebral blood flow glucose metabolism as previously reported, especially in the cerebellum.

Analysis of both TSC1 and TSC2 for germline mutations in 126 unrelated patients with tuberous sclerosis

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by the development of multiple hamartomas involving many organs. About two-thirds of the cases are sporadic and appear to represent new mutations. With the cloning of two causative genes, TSC1 and TSC2 it is now possible to analyze both genes in TSC patients and identify germline mutations. Here we report the mutational analysis of the entire coding region of both TSC1 and TSC2 genes in 126 unrelated TSC patients, including 40 familial and 86 sporadic cases, by single-stranded conformational polymorphism (SSCP) analysis followed by direct sequencing. Mutations were identified in a total of 74 (59%) cases, including 16 TSC1 mutations (5 sporadic and 11 familial cases) and 58 TSC2 mutations (42 sporadic and 16 familial cases). Overall, significantly more TSC2 mutations were found in our population, with a relatively equal distribution of mutations between TSC1 and TSC2 among the familial cases, but a marked underrepresentation of TSC1 mutations among the sporadic cases (P = 0.0035, Fisher's exact test). All TSC1 mutations were predicted to be protein truncating. However, in TSC2 13 missense mutations were found, five clustering in the GAP-related domain and three others occurring in exon 16. Upon comparison of clinical manifestations, including the incidence of intellectual disability, we could not find any observable differences between TSC1 and TSC2 patients. Our data help define the distribution and spectrum of mutations associated with the TSC loci and will be useful for both understanding the function of these genes as well as genetic counseling in patients with the disease.

Superiority of denaturing high performance liquid chromatography over single-stranded conformation and conformation-sensitive gel electrophoresis for mutation detection in TSC2

We evaluated denaturing high pressure liquid chromatography (DHPLC) as a scanning method for mutation detection in TSC2, and compared it to conformation-sensitive gel electrophoresis (CSGE) and single-stranded conformation polymorphism analysis (SSCP). The first 20 exons of TSC2 were amplified from 84 TSC patients and screened initially by CSGE and then by DHPLC. Optimization of DHPLC analysis of each exon was carried out by design of primers with minimum variation in the melting temperature of the amplicon, and titration of both elution gradient and temperature. CSGE analysis identified 40 shifts (21 unique) in the 84 patients and 20 exons. All of these variants were detected by DHPLC, and an additional 27 changes (14 unique) were identified. Overall 15 of 28 (54%) unique single base substitutions were detected by CSGE; all were detected by DHPLC. 25 definite or probable mutations were found in these 84 patients (30%) in exons 1-20 of TSC2. In a subsequent blinded analysis of 15 samples with 18 distinct TSC2 sequence variants originally detected by SSCP in another centre, all variants were detected by DHPLC except one where the variation occurred within the primer. Ten other (7 unique) sequence variants were detected in these samples which had not been detected by SSCP. Overall, 11 of 16 (69%) unique single base substitutions were detected by SSCP; all were detected by DHPLC. We conclude that DHPLC is superior to both CSGE and SSCP for detection of DNA sequence variation in TSC2, particularly for single base substitution mutations.

Microsatellite analysis of childhood leukemia: correlation of 9p and 12p chromosome abnormalities with expression of related genes

BACKGROUND

Loss of heterozygosity (LOH) and DNA replication error (RER) have been thought to be involved in carcinogenesis, but have not been investigated in childhood leukemia and lymphoma.

METHODS

Eighty samples from 65 patients with childhood leukemia and lymphoma were examined using seven different microsatellite markers for RER analysis. Additionally, LOH in two chromosome regions (9p and 12p) was investigated. Furthermore, expression of the TEL, TEL/AML1 and p27(KIP1) genes on 12p and the p16 gene on 9p were detected by reverse transcriptase polymerase chain reaction.

RESULTS

Replication errors were detected in 5/65 patients (7.7%). Most (4/5 patients) RER were preferentially located in the 9p and 12p regions. There were two patients who had DNA abnormalities in both 9p and 12p, one with common acute lymphoblastic leukemia (ALL) showed 9p LOH and the TEL/AML1 fusion gene on 12p and the other with common ALL and 12p RER had diminished expression of both the p27(KIP1) gene on 12p and the p16 gene on 9p.

CONCLUSIONS

Combined DNA alterations on 9p and 12p, involving LOH, RER and/or gene mutation and chromosomal translocation, were found in childhood acute leukemia, especially in common ALL.

Selectively induced high MRP gene expression in multidrug-resistant human HL60 leukemia cells

A subclone HL60/DOX was selected from a human leukemic HL60 cell line for resistance to doxorubicin (DOX) by exposure to stepwise increasing concentrations of the drug and coexposure to a potential P-glycoprotein (P-gp) inhibitor, cepharanthine (a biscoclaurine alkaloid). Compared with the parent HL60 cells, the HL60/DOX cells were 13.0-fold more resistant to DOX and showed multidrug-resistant (MDR) phenotype characterized by 4.6-fold, 2.3-fold, and 5.7-fold cross-resistance to vincristine, pirarubicin, and etoposide, respectively, but no cross-resistance to alkylating agent, cisplatin. Immunocytochemical analyses using the specific monoclonal antibody, MRPr1, and quantitative analyses using a competitive reverse transcription-polymerase chain reaction (CRT-PCR) confirmed overexpression of MRP gene products (about 8-fold determined by CRT-PCR) in this resistant clone. The P-gp expression was not detectable by the monoclonal antibody, C219, in the HL60/DOX cells, and that was consistent with extremely low levels of mdr1 mRNA expression determined by CRT-PCR in this clone. Drug accumulation and efflux studies demonstrated the significantly increased efflux rate of DOX compared to the parent HL60 cells. This enhancement of DOX efflux was reversed by the addition of 10 microM verapamil. To investigate the additional underlying mechanisms contributing to MDR phenotype in the HL60/DOX cells, the levels of DNA topoisomerases (Topo) including Topo I, Topo IIalpha, and Topo IIbeta, and gamma-glutamylcystein synthetase (y-GCS) expression were determined using CRT-PCR techniques. Normal expression of each enzyme at the transcriptional level was demonstrated in this resistant clone. Southern blot analysis of the gene organization in the HL60/DOX cells revealed the amplification of MRP gene. These results indicate that alteration of the drug accumulation from enhanced efflux appears to be a major mechanism(s) of MDR phenotype and attributable to high levels of MRP expression in the HL60/DOX cells. Overexpression of MRP in this clone is regulated by the genomic amplification of DNA and increased levels of the MRP mRNA, independently with the normal expression of Topo I, Topo IIalpha, Topo IIbeta, or gamma-GCS.

Oxidative stress causes enhanced endothelial cell injury in human heme oxygenase-1 deficiency

The first known human case of heme oxygenase-1 (HO-1) deficiency is presented in this report. The patient is a six-year-old boy with severe growth retardation. He has been suffering from persistent hemolytic anemia characterized by marked erythrocyte fragmentation and intravascular hemolysis, with paradoxical increase of serum haptoglobin and low bilirubin. An abnormal coagulation/fibrinolysis system, associated with elevated thrombomodulin and von Willebrand factor, indicated the presence of severe, persistent endothelial damage. Electron microscopy of renal glomeruli revealed detachment of endothelium, with subendothelial deposition of an unidentified material. Iron deposition was noted in renal and hepatic tissue. Immunohistochemistry of hepatic tissue and immunoblotting of a cadmium-stimulated Epstein-Barr virus-transformed lymphoblastoid cell line (LCL) revealed complete absence of HO-1 production. An LCL derived from the patient was extremely sensitive to hemin-induced cell injury. Sequence analysis of the patient's HO-1 gene revealed complete loss of exon-2 of the maternal allele and a two-nucleotide deletion within exon3 of the paternal allele. Growth retardation, anemia, iron deposition, and vulnerability to stressful injury are all characteristics observed in recently described HO-1 targeted mice. This study presents not only the first human case of HO-1 deficiency but may also provide clues to the key roles played by this important enzyme in vivo.

Diffuse brain damage caused by acute twin-twin transfusion during late pregnancy

BACKGROUND

Monoamniotic twinning is a relatively rare event with increased antenatal and perinatal mortality. We describe a brain damage detected in a surviving monoamniotic twin after intrauterine death of the co-twin at 37 weeks of gestation.

RESULTS

Severe entanglement and knotting of the umbilical cords was apparent at the time of delivery and a portion of the cord to the dead twin was narrowed significantly. It was suggested that transfer of blood occurred across placental anastomoses from the survivor to the dead fetus, resulting in transient but severe hypovolemia in the survivor. It is difficult to prevent this type of brain damage because the course of acute twin-twin transfusion is very rapid and the damage has already occurred by the time the death of the twin is diagnosed.

CONCLUSIONS

We suggest that elective delivery should be considered in cases of monoamniotic twin pregnancies with additional risk factors.

Pharmacokinetics and safety of a new parenteral carbapenem antibiotic, biapenem (L-627), in elderly subjects

The pharmacokinetics and tolerability of a new parenteral carbapenem antibiotic, biapenem (L-627), were studied in healthy elderly volunteers aged 65 to 74 years (71.6 +/- 2.7 years [mean +/- standard deviation], n = 5; group B) and > or = 75 years (77.8 +/- 1.9 years, n = 5; group C), following single intravenous doses (300 and 600 mg), and compared with those of healthy young male volunteers aged 20 to 29 years (23.0 +/- 3.5 years, n = 5; group A). The agent was well tolerated in all three age groups. Serial blood and urine samples were analyzed for biapenem to obtain key pharmacokinetic parameters by both two-compartment model-dependent and -independent methods. The maximum plasma concentration and area under plasma concentration-versus-time curve (AUC) increased in proportion to the dose in all three groups. Statistically significant age-related effects for AUC, total body clearance, and renal clearance (CLR) were found, while elimination half-life (t1/2 beta) and percent cumulative recovery from urine of unchanged drug (% UR) remained unaltered (t1/2 beta, 1.51 +/- 0.42 [300 mg] and 2.19 +/- 0.64 [600 mg] h [group A], 1.82 +/- 1.14 and 1.45 +/- 0.36 h [group B], and 1.75 +/- 0.23 and 1.59 +/- 0.18 h [group C]; % UR, 52.6% +/- 3.0% [300 mg] and 53.1% +/- 5.1% [600 mg] [group A], 46.7% +/- 7.4% and 53.0% +/- 4.8% [group B], and 50.1% +/- 5.2% and 47.1% +/- 7.6% [group C]). A significant linear correlation was observed between the CLR of biapenem and creatinine clearance at the dose of 300 mg but not at 600 mg. The steady-state volume of distribution tended to be decreased with age, although not significantly. Therefore, the age-related changes in parameters of biapenem described above were attributable to the combination of decreased lean body mass and lowered renal function of the elderly subjects. However, the magnitude of those changes does not necessitate dosage adjustment in elderly patients with normal renal function for their age.

[Activation of bradykinin formation cascade on receiving autologous blood transfusion through a white cell-reduction filter in a patient treated with an ACE inhibitor]

We have experienced a case of anaphylactoid reaction on receiving autologous blood transfusion through a WBC filter for packed red blood cell (PRBC). The patient was a 71-year-old man with a history of hypertension treated with oral antihypertensive drug; enalapril, an angiotensin converting enzyme (ACE) inhibitor, who received anesthesia for Y-graft replacement. Autologous blood was obtained after the induction of general anesthesia in the operating room. Upon starting to return the stored blood with an unintentional use of a WBC filter, arterial blood pressure (ABP) fell within the first minute of the transfusion. We obtained three blood samples; pre-filtered blood (PRE), postfiltered blood (POST) and arterial blood (CIRC) after the event, and analyzed concentrations of bradykinin (BK), high molecular weight kininogen (HMWK) and high molecular weight kininogen-light chain (HMWK-LC). BK was higher in POST than in PRE. HMWK was lower in POST than in PRE, while HMWK-LC was higher in POST than in PRE. HMWK in CIRC was lower than in PRE, and HMWK-LC was higher in CIRC than in PRE. HMWK and HMWK-LC changes after the event suggest that BK formation cascade in the patient was activated on receiving the transfusion. ACE inhibitors were reported to augment such activation. The WBC filter has the negatively charged surface on filteration material and may activate the cascade. While WBC filters can avoid transfusion related reactions, hemodynamic responses should be watched closely in patients treated with ACE inhibitors.

Novel Fas (CD95/APO-1) mutations in infants with a lymphoproliferative disorder

Fas is an apoptosis-signaling receptor important for homeostasis of the immune system. In this study, Fas-mediated apoptosis and Fas mutations were analyzed in three Japanese children from two families with a lymphoproliferative disorder characterized by lymphadenopathy, hepatosplenomegaly, pancytopenia, hypergammaglobulinemia and an increase in TCR alphabeta+ CD4- CD8- T cells. Apoptosis induced by anti-Fas mAb was defective in both activated T cells and B cells, and granulocytes from these patients. Truncated Fas receptor lacking the cytoplasmic death domain caused by a point mutation in the splice region of intron 7 were demonstrated in two siblings. A homozygous point mutation in the splice acceptor of intron 3 was found in the Fas gene of the third patient, which resulted in the skipping of exon 4 and complete loss of Fas expression. Corresponding to these mutations, soluble Fas concentrations were decreased and reciprocally soluble Fas ligands were increased in patients' sera. Interestingly, co-stimulation by immobilized anti-Fas mAb in T cells from the two siblings was comparable to that seen in normal T cells. These results suggest that Fas-mediated apoptosis plays a pivotal role in immunological homeostasis in vivo, especially regarding clonal deletion of immune cells in humans.

Deficient expression of Bruton's tyrosine kinase in monocytes from X-linked agammaglobulinemia as evaluated by a flow cytometric analysis and its clinical application to carrier detection

The B-cell defect in X-linked agammaglobulinemia (XLA) is caused by mutations in the gene for Bruton's tyrosine kinase (BTK). Using the anti-BTK monoclonal antibody (48-2H), a flow cytometric analysis of intracytoplasmic BTK protein expressed in monocytes was successfully performed. To examine the possible identification of XLA patients and female carriers by this assay, we studied 41 unrelated XLA families with (35) or without (6) known BTK mutations. A flow cytometric assay showed deficient expression of the BTK protein in 40 of 41 patients, complete BTK deficiency in 35, and partial BTK deficiency in 5. One patient exhibited a normal level of BTK expression. All 6 patients with partial BTK deficiency or normal BTK expression had missense BTK mutations. The cellular mosaicism of BTK expression in monocytes from obligate carriers was clearly shown in 35 of 41 families. The results suggested that most BTK mutations in XLA might result in deficient expression of the BTK protein. We conclude that deficient expression of BTK protein can be evaluated by a flow cytometric assay, and the clinical usefulness and limitations in diagnosis of XLA patients and carriers are discussed.

[A psychological burden on patients with clinical trials during anesthesia]

We investigated with questionnaires, psychological outline of 30 patients, who were requested to participate in clinical trials of anti-tachycardia drugs during anesthesia. Although 14 patients consented to the trial, the consent was not based on adequate understanding or volunteerism in 3 patients. Nine patients of the consented group were anxious about the possible use of the trial drug. Eight patients of the rejected group felt anxiety on surgery and anesthesia, which was the most common reason for rejection. Forty % of refused patients felt a guilty conscience or embarrassed. Although we tried to obtain patients' consent following governmental and institutional regulations and guidelines, not only the consented but also the refused patients suffer from psychological burden with the clinical trial. It is of concern that recruitment to the trial enhances anxiety of the patients as they already feel uneasiness, unrest, and insecurity facing anesthesia and surgery. To avoid entry of less informed or unwilling patients to the clinical trial, we must secure patients' veto, and recruitment should be performed by clinicians who are not involved in anesthesia practice.

Simple, rapid and sensitive method for the determination of indomethacin in plasma by high-performance liquid chromatography with ultraviolet detection

A micro method for determination of indomethacin in plasma was developed. Following deproteinization of plasma with acetonitrile containing internal standard (mefenamic acid), the separation of indomethacin and internal standard was achieved by high-performance liquid chromatography using a 7 microm LiChrosorb-RP18 column (250x4 mm I.D.) at 50 degrees C. The mobile phase was 6 mM phosphoric acid-acetonitrile (50:50). The flow-rate was kept at 2.0 ml/min and the column effluent was monitored at 205 nm. The coefficients of variation of the method estimated at 0.2 and 1.0 microg/ml were 4.2 and 2.3%, and the detection limit of the drug was about 0.05 microg/ml (S/N=5). The method requires minimum pretreatment of the plasma with a small sample volume (25 microl), and is very suitable for therapeutic drug monitoring of indomethacin in premature infants with symptomatic patent ductus arteriosus.

Urinary excretion of mefenamic acid and its metabolites including their esterglucuronides in preterm infants undergoing mefenamic acid therapy

Urinary excretion of mefenamic acid (MA) and its two oxidative metabolites, M-I (3'-hydroxymethyl derivative) and M-II (3'-carboxyl derivative), and their glucuronides was investigated in preterm infants undergoing MA therapy. MA was given orally at a dose of 2 mg/kg and the dose was repeated every 24 h a maximum of three times. Urine was collected for up to 5 d after the last dose, and MA and the metabolites were determined by a newly developed HPLC. The cumulative amounts of MA and the metabolites excreted in the urine varied from 7 to 46% of the total dose administered, and were less than those reported in adults and children. Significant correlation was observed between the plasma half-life of MA and the cumulative amount of MA and the metabolites excreted in the urine. These results suggest that long plasma half-lives of MA observed in preterm infants are due mainly to low activity of drug metabolizing enzyme(s). In an infant who received the two regimens of MA therapy about 2 weeks apart, the plasma half-life of MA was shortened and the urinary excretion of the MA metabolites including their glucuronides was greatly increased during this period. It is suggested that the activities of both cytochrome P-450(s) and glucuronyltransferase(s) related to MA metabolism rapidly increased during the first month of the infant's life.

Identification of Bruton's tyrosine kinase (Btk) gene mutations and characterization of the derived proteins in 35 X-linked agammaglobulinemia families: a nationwide study of Btk deficiency in Japan

Deficiencies of Bruton's tyrosine kinase (Btk) have been implicated in the pathogenesis of human X-linked agammaglobulinemia (XLA). The distinctive phenotype observed in B-cell deficiency indicates the crucial role of Btk in B-cell development. This report describes a nationwide study of Btk deficiency in Japan, covering 51 XLA patients (35 independent families). Along with the identification of mutations, the resulting protein products were characterized by an in vitro kinase assay and a Western blot analysis. Thirty-one of the families were found to have mutations in the coding region of Btk. Although mutations were not found in the cDNA of 4 families, the Btk transcripts of these patients were greatly reduced. The identification of several novel missense mutations, in combination with the result of other studies, clarified the presence of two (missense) mutation hot spots, one in the SH1 and the other in the PH domain. The absence of kinase activity seen in 32 of the families underscored the importance of Btk protein analysis as a diagnostic indicator of XLA. The protein analysis also clarified the different effects of missense mutations on kinase activity and protein stability.

Expression of L-selectin (CD62L) discriminates Th1- and Th2-like cytokine-producing memory CD4+ T cells

Human memory (CD45RO+) CD4+ T cells can be distinguished into two subpopulations on the basis of expression of the lymph node homing receptor, L-selectin (CD62L). In a prior study we showed that human L-selectin-positive memory T-helper (Th) cells promote the maturation of IgG- and IgA-producing cells by naive B cells. To further elucidate the contribution of memory CD4+ T cells to B-cell differentiation, human memory CD4+ T cells with or without L-selectin expression were evaluated for production of cytokines that participate in regulation of immunoglobulin production. It was found that L-selectin-positive human memory CD4+ T cells produce mainly interleukin (IL)-4 and IL-5, whereas L-selectin-negative CD4+ T cells produce mainly interferon-gamma (IFN-gamma). This profile of cytokine expression coincides with the profile that distinguishes Th1 and Th2 subsets. In contrast to the murine system, IL-10 production was similarly contributed by human L-selectin-positive and -negative memory CD4+ T-cell subpopulations. These results suggest that the human L-selectin-negative and -positive subpopulations of human memory CD4+ T cells contain Th1-like and Th2-like cytokine-producing cells, respectively.

Pharmacokinetics of mefenamic acid in preterm infants with patent ductus arteriosus

The pharmacokinetics of mefenamic acid (MA), 2 mg/kg, were studied in 17 preterm infants with symptomatic patent ductus arteriosus. They were given this dosage orally at 24 h intervals. There were marked inter-individual differences in some of the pharmacokinetic parameters after the first dose; peak plasma concentration (Cmax) varied from 1.2 to 6.1 micrograms/mL with a mean of 3.8 micrograms/mL, time to reach Cmax (tmax) varied from 2 to 18 h with a mean of 7.7 h and plasma half-life (t1/2) varied from 3.8 to 43.6 h with a mean of 18.7 h. The group of infants (10/17) who had ductus closure after the first dose had significantly lower clearance (P < 0.01), longer t1/2 (P < 0.01) and higher 24 h plasma concentration (P < 0.001) compared to the group of infants (7/17) who had no ductus closure after the first dose. It appeared that the plasma concentration of MA had to be above 2.0 micrograms/mL and maintained at this concentration for at least 12 h for MA associated with ductus closure in preterm infants to take effect. In view of the inter-individual variation of plasma MA concentration and the effective plasma concentration, we suggest that measurement of the plasma concentration should be done 24 h after the first dose. This might be useful for safe and effective therapy for infants with ductus closure failure after the first dose.

An acrosomal protein, sp32, in mammalian sperm is a binding protein specific for two proacrosins and an acrosin intermediate

An acrosomal protein, sp32, was completely purified from acid extracts of ejaculated porcine sperm. Purified sp32 gave a single 32-kDa protein band on SDS-polyacrylamide gel electrophoresis and was characterized as a binding protein specific for 55-, 53-, and 49-kDa forms of (pro)acrosin. This protein was not capable of binding a 43-kDa acrosin intermediate and 35-kDa mature acrosin. sp32 significantly accelerated autoactivation of proacrosin at a basic pH in vitro and affected the maturation pathway of proacrosin. In the presence of sp32, the 49-kDa acrosin intermediate from the 55- and 53-kDa proacrosins was accumulated, instead of the 43-kDa acrosin intermediate. These results suggest that sp32 interacts with both the amino- and carboxyl-terminal sequences of the 53-kDa proacrosin. The cDNA clones coding for porcine and guinea pig sp32 have been identified from testis cDNA libraries in lambda gt11. The deduced amino acid sequence indicates that sp32 is initially synthesized as a 61-kDa precursor protein with a putative signal peptide at the amino terminus. The carboxyl-terminal half of the precursor molecule corresponds to the mature sp32. Thus, sp32 is produced by post-translational modification of the precursor. The binding of sp32 to proacrosin may be involved in packaging the acrosin zymogen into the acrosomal matrix.

Mature helper T cell requirement for immunoglobulin production by neonatal native B cells injected intraperitoneally into severe combined immunodeficient (SCID) mice

It is accepted that human neonatal naive B cells produce mainly IgM in vivo as well as in vitro. Our previous work has demonstrated that i.p. injection of neonatal B cells together with adult mature T cells induces substantial levels of human IgG in the serum of SCID recipient mice. The present study was further attempted to determine the cellular components required for immunoglobulin production by neonatal B cells in SCID mice. When neonatal B and adult T cells were transferred into the SCID mice, human immunoglobulins, largely of IgG, were maximally detected in the serum around 6 weeks after a cell transfer. Depletion of CD4+ T cells from adult T cells resulted in undetectable levels of human immunoglobulin in the serum. By contrast, CD4+ T cell-enriched populations exhibited an enhancing effect on immunoglobulin production by neonatal B cells. Higher levels of immunoglobulin, including IgA and IgM, were detected in the peritoneal fluid than in the serum as early as 2 weeks after the cell transfer. Human T cells expressing activation antigens such as CD45RO and HLA-DR antigens were identified in the peritoneal lavages. These results suggest that neonatal naive B cells are able to differentiate into cells producing all classes of immunoglobulin in the presence of mature CD4+ T cells in a SCID mouse environment. The peritoneal cavity of SCID mice appears to provide a suitable place for immune responses by human cells, possibly in association with a certain xenogeneic reaction.

Resetting of regional preload due to ventricular shape change alters diastolic and systolic performance

The diastolic and systolic pressure of one ventricle is increased by an increase in volume and/or pressure of the opposite ventricle; however, a mechanism for the ventricular interaction remains unclear. We hypothesized that the shape change of one ventricle elicited by the opposite ventricle would lead to resetting of the regional length, which may explain the ventricular interaction. We used 15 cross-circulated isovolumically contracting canine hearts in which both ventricular volumes were independently controlled. Diastolic regional segment area was calculated by multiplying circumferential and longitudinal lengths on right ventricular free wall (RVFW; n = 6), interventricular septum (IVS; n = 11), and left ventricular (LV) FW (n = 12). The regional area at relatively small volumes of both ventricles were expressed as 100%. With constant RV volume, increasing LV from 7 to 19 ml increased RV diastolic and systolic pressures by 2.7 and 5.5 mmHg, respectively. Conversely, increasing RV volume increased LV diastolic and systolic pressures by 2.3 and 7.5 mmHg, respectively. Increasing LV volume increased RVFW regional area from 121.0 to 124.6% (P < 0.01) and increased IVS regional area from 103.3 to 108.7% (P < 0.01), whereas the RV volume was held constant. Increasing RV volume also increased LVFW and IVS regional areas from 109.9 to 111.6% (P < 0.01) and from 106.8 to 108.9% (P < 0.05), respectively. Ventricular shape change elicited by ventricular interaction will increase the regional wall area, even though the volume of the chamber is unchanged. The increase in the regional area alters the position of the tissue on its resting and active length-tension relations and, thus, leads to enhancement of the chamber pressure.

Evaluation of diagnostic assays for neonatal and infantile chlamydial infections

Several diagnostic assays for neonatal and infantile chlamydial infections, isolation with tissue culture, antigen detection by enzyme immunoassay (EIA) (IDEIA Chlamydia test), a nonisotopic DNA probe (Gen-Probe PACE 2 assay), serum IgM antibody detection by EIA (SeroELISA Chlamydia TRUE IgM), and polymerase chain reaction (PCR), were evaluated. Of 210 clinical specimens (170 nasopharyngeal and 40 conjunctival swabs) from 53 neonates and 102 infants with respiratory insufficiency and respiratory tract infections which were suspected to be associated chlamydial infection, chlamydial antigens were detected in 30 by IDEIA Chlamydia. Of these 30 samples, C. trachomatis was isolated from 27 specimens. Samples from 15 neonates and 6 infants were culture-positive and IDEIA Chlamydia-positive. Of 30 samples, 27 were tested with PCR and 8 with DNA probe. Twenty-three of 27 specimens were positive with PCR, while only one specimen was positive with DNA probe. EIA can be used for the diagnosis and screening of neonatal and infantile chlamydial infections.

[Evaluation of chlamydial IgM antibodies for clinical diagnosis]

Chlamydia trachomatis (C. trachomatis), C. psittaci, and C. pneumoniae are now well established as pathogens of respiratory infections including pneumonia. Serum samples from 223 infants and children with pneumonia, 31 patients with adult inclusion conjunctivitis, 16 parents of babies with neonatal inclusion conjunctivitis and others were tested for IgM antibodies to Chlamydiae. Diagnostic kits for chlamydial IgM antibodies (SeroELISA and IPAzyme) have been also evaluated for their diagnostic value. It was found that detection of specific IgM antibodies with SeroELISA has a diagnostic value in chlamydial pneumonias.

Remarkable changes in the plasma levels of pituitary protein "7B2" during childhood

We measured plasma immunoreactive (IR)-7B2 concentrations in 96 children (57 males and 39 females) from the newborn period to 20 yr of age. Plasma IR-7B2 concentrations in infants less than 2 yr of age (range 175-580 pg/ml, n = 19) were much higher than those in adults (range 20-138 pg/ml). Plasma levels of IR-7B2 decreased with age during childhood to reach the adult level at 15-20 yr. Significant negative correlations were found between plasma levels of IR-7B2 and dehydroepiandrosterone sulfate (r = -0.4154, p less than 0.05, n = 27), luteinizing hormone (r = -0.4948, p less than 0.05, n = 20) and follicle-stimulating hormone (r = -0.4682, p less than 0.05, n = 20). The possibility of a relationship between the reduction of plasma IR-7B2 levels and pubertal development warrants attention.

Lactoferrin in middle ear effusion

Lactoferrin (LF) level in the middle ear effusion of patients with otitis media with effusion (OME) was determined by using an Enzyme-linked immunosorbent assay (ELISA) to find the information on non-specific immunity in the middle ear cavity. Lactate dehydrogenase (LDH), an intracellular enzyme, was also measured by spectrophotometer. We investigated cytological findings of middle ear effusion and classified cellular findings into five classes; Neutrophil dominant type, Lymphocytic-monocytic type, Mixed type, Cellular remnants type, and Too few cells type. LF and LDH levels in average: Serum, LF 1.14 microgram/ml, LDH 330.4 IU/l; Few cells type, LF 45.25 micrograms/ml, LDH 2,727.5 IU/l; Lymphocytic-monocytic type, LF 107.11 micrograms/ml, LDH 10,197.8 IU/l; Neutrophil dominant type, LF 99.73 micrograms/ml, LDH 10,580 IU/l; Mixed type, LF 163.71 micrograms/ml, LDH 19,342.9 IU/l; Cellular remnants type, LF 127.6 micrograms/ml, LDH 9,122 IU/l. LF level is high when cellular factors are rich in middle ear effusion.