Extensive chromosome translocation in a clinical isolate showing the distinctive carbohydrate assimilation profile from a candidiasis patient

Variation of the electrophoretic karyotype is common among clinical strains of Candida albicans and chromosome translocation is considered one of the causes of karyotypic variation. Such chromosome translocations may be a mechanism to confer phenotypic diversity on the imperfect fungus C. albicans. A clinical strain, TCH23, from a vaginal candidiasis patient shows distinct carbohydrate assimilation profile, serotype B, no chlamydospore formation and an atypical karyotype (Asakura et al., 1991). To examine the taxonomic relationship among C. albicans, Candida dubliniensis and this strain, we sequenced the internal transcribed spacer 1 (ITS1) of nuclear ribosomal DNA. The ITS1 sequence of TCH23 was identical with that of C. albicans but not of C. dubliniensis. Thus, strain TCH23 was classified as a variant of C. albicans with an atypical phenotype. The chromosomal DNAs of this strain were resolved into 13 bands on pulse-field gel electrophoresis (PFGE). Using DNA probes located at or near both ends of each chromosome of C. albicans, we investigated the chromosome organization of this strain. Referring to the SfiI map of C. albicans 1006 (Chu et al., 1993), we found that seven chromosomal DNA bands in strain TCH23 were reciprocal chromosome translocations. One homologue from chromosomes 1, 2 and 6 and both homologues from chromosomes 4 and 7 participated in these events. One translocation product was composed of three SfiI fragments, one each from chromosomes 2, 4 and 7. We deduced the breakpoints of chromosome translocation from the physical map of this strain; between 1J and 1J1, between 2A and 2U, both ends of 4F2, between 6C and 6O and both ends of 7F.     

Repeated administration of opioids alters characteristics of membrane-bound phorbol ester binding in rat brain

Scatchard analysis of saturation binding data indicated that dissociation constant (KD) of [3H]phorbol 12,13-dibutyrate (PDB) binding to the membrane-bound protein kinase C of rat cortex and midbrain was significantly decreased following systemic repeated administration of morphine (mu-opioid receptor agonist) and butorphanol (mu/delta/kappa-mixed opioid receptor agonist). No change in the receptor density (Bmax) of [3H]PDB binding was found following repeated treatment with morphine and butorphanol. On the other hand, neither the Bmax nor KD values in pons/medulla were altered in these rats. These results suggest that systemic repeated opioid treatment, such as morphine and butorphanol leads to an increased affinity for phorbol ester binding to the membrane-bound protein kinase C in rat cortex and midbrain.     

Successful polymerase chain reaction-based diagnosis of fungal meningitis in a patient with chronic granulomatous disease

The structural and electronic properties of seventeen alkylxanthine derivatives were calculated using the MO program PM3 to elucidate the key features related to their inhibitory activity on phosphodiesterase (PDE) IV isoenzyme. Except for 7-alkylxanthine derivatives, a good correlation could be established between the distance between the tops of the two alkyl groups at the N1 and N3 positions of the xanthine skeleton (molecular length) and the PDE IV inhibitory activity (r=0.973, n=13). The same inhibitory activity could also be significantly correlated with the following electronic parameters of alkylxanthines: HOMO energy (r=0.850), absolute hardness (r=-0.806), and absolute electronegativity (r=-0.825). These results suggest that the electronic properties are partly responsible for PDE IV inhibition as far as the effects of structural properties associated with molecular length are concerned. Alkylxanthines may also act as electron donors in the charge-transfer interaction with the active sites on PDE IV isoenzyme.     

Unbiased InP detectors in the submillimetre wave region

High sensitivity unbiased detectors employing Ni-nInP Schottky-barrier diodes have been developed in a submillimetre-wave region. The voltage sensitivities of 120 V/W at 300 GHz and 17 V/W at 450 GHz were obtained, which are about three times higher than those of the usually used unbiased Si point contact diode detectors.     

Pulsed source of ultra low energy positive muons for near-surface μSR studies

We have produced a pulsed beam of low energy (ultra slow) polarized positive muons (LE-μ⁺) and performed several demonstration muon spin rotation/relaxation (μSR) experiments at ISIS RIKEN-RAL muon facility in UK. The energy of the muons implanted into a sample is tuneable between 0.1 keV and 18 keV. This allows us to use muons as local magnetic microprobes on a nanometre scale. The control over the implantation depth is from several nanometres to hundreds of nanometres depending on the sample density and muon energy. The LE-μ⁺ are produced by two-photon resonant laser ionization of thermal muonium atoms. Currently ∼15 LE-μ⁺/s with 50% spin polarization are transported to the μSR sample position, where they are focused to a small spot with a diameter of only 4 mm. The overall LE-μ⁺ generation efficiency of 3 × 10⁻⁵ is comparable to that obtained when moderating the muon beam to epithermal energies in simple van der Waals bound solids. In contrast to other methods of LE-μ⁺ generation, the implantation of the muons into the sample can be externally triggered with the duration of the LE-μ⁺ pulse being only 7.5 ns. This allows us to measure spin rotation frequencies of up to 40 MHz.     

A mathematical model for computer simulation of the direct continuous esterification process between terephthalic acid and ethylene glycol. Part II: Reaction rate constants

It has been confirmed that the reaction model proposed previously, which can express simultaneously the oligomer properties and the distillate properties under low esterification pressure, is applicable to a continuous direct esterification process in a practical plant. The experimental data of the first esterification reactor (RA-1) was obtained under low reaction pressures (atomospheric or 1 kg/cm²G) with the pilot plant throughput based on poly(ethylene terephthalate) (PET) polymer production of about 50 kg/h. The Arrhenius' parameters, frequency factor, and apparent activation energy, were determined fitting the experimental data of the pilot plant by using the Simplex method as an optimization technique. The activation energy of diethylene glycol (DEG) formation, E₇, is about twice as much as those of the esterifications, E₁, E₂, E₃, and E₄. The activation energies are E₁, = 19640 cal/mol, E₂ = 18140, E₃ = 22310, E₄ = 18380, E₅ = 2810, E₆ = 14960, and E₇ = 42520 cal/mol. Good agreement was obtained between experimental data and calculated predictions for several oligomer and distillate properties. The vapor-liquid equilibrium can be expressed by Raoult's law with little problem of practical use.     

Development of a ligation-based impedimetric DNA sensor for single-nucleotide polymorphism associated with metabolic syndrome

Single-nucleotide polymorphism (SNP) detection is becoming important in molecular diagnostics, clinical assay, and novel drug development. Electrochemical methods are well suited for the DNA diagnostics system. Since electrochemical reactions directly emit an electronic signal, expensive signal transduction equipment is not required. We describe the development of a novel DNA sensor that utilizes impedance spectroscopy and DNA ligation reaction on a gold electrode. Impedance spectroscopy enables label-free detection and is nondestructive and useful in equivalent circuit models for interpretation on an electrode surface, whereas from the ligation reaction, the specificity is derived by the allele-specific oligonucleotide of the capture probe on immobilized gold electrode. In other words, DNA diagnostics system using the combination of impedance spectroscopy and ligation reaction is simple, rapid, and allele specific. In this report, we have described a ligation-based impedimetric DNA sensor and the analysis of Trp64Arg polymorphism in the beta3-adrenergic receptor gene (ADRβ3).     

80 GHz silicon diamond-heatsink Impatt diodes

80 GHz band silicon d.d.r. Impatt diodes with diamond heatsinks were fabricated. An output power of 1014 mW at 77.70 GHz was obtained by liquid-nitrogen-cooled operation, which gives the highest pf2 product, and 726 mW at 73.35 GHz by room temperature operation. Small-signal diode impedance was calculated considering operating temperature.     

A multifunctional 3.5 V iron-based phosphate cathode for rechargeable batteries

In the search for new positive-electrode materials for lithium-ion batteries, recent research has focused on nanostructured lithium transition-metal phosphates that exhibit desirable properties such as high energy storage capacity combined with electrochemical stability. Only one member of this class--the olivine LiFePO(4) (ref. 3)--has risen to prominence so far, owing to its other characteristics, which include low cost, low environmental impact and safety. These are critical for large-capacity systems such as plug-in hybrid electric vehicles. Nonetheless, olivine has some inherent shortcomings, including one-dimensional lithium-ion transport and a two-phase redox reaction that together limit the mobility of the phase boundary. Thus, nanocrystallites are key to enable fast rate behaviour. It has also been suggested that the long-term economic viability of large-scale Li-ion energy storage systems could be ultimately limited by global lithium reserves, although this remains speculative at present. (Current proven world reserves should be sufficient for the hybrid electric vehicle market, although plug-in hybrid electric vehicle and electric vehicle expansion would put considerable strain on resources and hence cost effectiveness.) Here, we report on a sodium/lithium iron phosphate, A(2)FePO(4)F (A=Na, Li), that could serve as a cathode in either Li-ion or Na-ion cells. Furthermore, it possesses facile two-dimensional pathways for Li+ transport, and the structural changes on reduction-oxidation are minimal. This results in a volume change of only 3.7% that--unlike the olivine--contributes to the absence of distinct two-phase behaviour during redox, and a reversible capacity that is 85% of theoretical.