De novo epileptic confusional status in a patient with cobalamin deficiency

A 80-year-old man with cobalamin deficiency and no history of epilepsy developed a partial complex epileptic confusional status (ECS) unresponsive to acute i.v. diazepam. Brain CT scan and MRI investigation ruled out a focal cerebral lesion. Therapy with high doses (10,000 micrograms i.m. daily) of cobalamin alone was started, and the patient fully recovered in the following 72-hour. Control EEGs repeatedly performed days and weeks later showed progressive disappearance of the frontal interictal spiking, while the patient was on monotherapy with cobalamin (5,000 micrograms i.m. weekly). A month later the patient unfortunately discontinued replacement therapy and 13 weeks later he developed a fatal convulsive epileptic status. To our knowledge the association of ECS and cobalamin deficiency has not been previously reported.     

COMMENTS ON THE DETERMINATION OF FRIABILITY AND UNMODIFIED GRAINS

The Analysis Committee of the European Brewery Convention is aware that the Friabilimeter sometimes is used on samples that do not comply with the field of application. The precision of the method is also overlooked by some users. The field of application, precision of the method as well as the need for frequent testing of the instrument is therefore stressed in more detail than in the earlier published method by the EBC Analysis Committee.     

Multiterminal light-emitting logic device electricallyreprogrammable between OR and NAND functions

A monolithic multiterminal logic device that functions both optically and electrically as an ORNAND gate, is demonstrated for the first time. The device, based on the real-space transfer of hot electrons into a complementary collector layer, has been implemented in an InGaAs/InAlAs/InGaAs heterostructure grown by molecular beam epitaxy. Excellent performance is obtained at room temperature. The collector current and the optical output power both exhibit the OR and the NAND functions of any two of the three input terminals, these functions being interchangeable by the voltage on the third terminal     

Crystal structure of tRNA-guanine transglycosylase: RNA modification by base exchange

tRNA-guanine transglycosylases (TGT) are enzymes involved in the modification of the anticodon of tRNAs specific for Asn, Asp, His and Tyr, leading to the replacement of guanine-34 at the wobble position by the hypermodified base queuine. In prokaryotes TGT catalyzes the exchange of guanine-34 with the queuine (.)precursor 7-aminomethyl-7-deazaguanine (preQ1). The crystal structure of TGT from Zymomonas mobilis was solved by multiple isomorphous replacement and refined to a crystallographic R-factor of 19% at 1.85 angstrom resolution. The structure consists of an irregular (beta/alpha)8-barrel with a tightly attached C-terminal zinc-containing subdomain. The packing of the subdomain against the barrel is mediated by an alpha-helix, located close to the C-terminus, which displaces the eighth helix of the barrel. The structure of TGT in complex with preQ1 suggests a binding mode for tRNA where the phosphate backbone interacts with the zinc subdomain and the U33G34U35 sequence is recognized by the barrel. This model for tRNA binding is consistent with a base exchange mechanism involving a covalent tRNA-enzyme intermediate. This structure is the first example of a (beta/alpha)-barrel protein interacting specifically with a nucleic acid.     

Application of the integral definition of the curl operator tonumerical solutions in electromagnetics

The definition of the curl operator in terms of an integral is shown to lead to a method for numerical solutions that facilitates the use of mixtures of cells having different shapes and different dielectric properties. The derivation is followed by examples for, waveguides, mixtures of different cells, and a method for increasing the accuracy when an equation is known for the field on the outer boundary. Thus, these results suggest that the formal definition of the curl operator has more than pedagogical value. This definition is taught in an undergraduate class at Florida International University     

Enhanced electron emission from phosphorus-doped diamond-cladsilicon field emitter arrays

Undoped and phosphorus (P)-doped diamond-clad Si field emitter arrays have been successfully fabricated using microwave plasma chemical vapor deposition (MPCVD) technology. The electron emission from the blunt diamond-clad microtips are much higher than those for the pure Si tips with sharp curvature due to a lower work function. Furthermore, the characteristics of emission current against applied voltage for the P-doped diamond-clad tips show superior emission at lower field to the undoped ones. After the examination of Auger electron spectroscopy (AES) and electrical characteristics of as-grown diamond, such a significant enhancement of the electron emission from the P-doped diamond-clad tips is attributed to a higher electron conductivity and defect densities     

The natural killer cell receptor specific for HLA-A allotypes: a novel member of the p58/p70 family of inhibitory receptors that is characterized by three immunoglobulin-like domains and is expressed as a 140-kD disulphide-linked dimer

Human natural killer (NK) cells express inhibitory receptors that are specific for different groups of HLA-C or HLA-B alleles. The majority of these receptors belong to the immunoglobulin (Ig) superfamily and are characterized by two or three extracellular Ig-like domains. Here we describe a novel inhibitory NK receptor that is specific for a group of HLA-A alleles. The HLA-A3-specific NK cell clone DP7 has been used for mice immunization. Two mAbs, termed Q66 and Q241, bound to the immunizing clone and stained only a subset of NK cell populations or clones. Among Q66 mAb-reactive clones, we further selected those that did not express any of the previously identified HLA-class I-specific NK receptors. These clones did not lyse HLA-A3+ (or -A11+) target cells, but lysis of these targets could be detected in the presence of Q66 or Q241 mAbs. On the other hand, target cells expressing other HLA-A alleles, including -A1, -A2, and -A24, were efficiently lysed. Moreover, none of the HLA-C or HLA-B alleles that were tested exerted a protective effect. Q66+, but not Q66- NK cell clones, expressed messenger RNA coding for a novel 3 Ig domain protein homologous to the HLA-C (p58) and HLA-B (p70) receptors. The corresponding cDNA (cl.1.1) was used to generate transient and stable transfectants in COS7 and NIH3T3 cell lines, respectively. Both types of transfectants were specifically stained by Q66 and Q241 mAbs. Since the cytoplasmic tail of Q66-reactive molecules was at least 11 amino acid longer than the other known p58/p70 molecules, we could generate an antiserum specific for the COOH-terminus of Q66-reactive molecules, termed PGP-3. PGP-3 immunoprecipitated, only from Q66+ NK cells, molecules displaying a molecular mass of 140 kD, under nonreducing conditions, which resolved, under reducing conditions, in a 70-kD band. Thus, differently from the other p58/p70 receptors, Q66-reactive molecules appear to be expressed as disulphide-linked dimers and were thus termed p140. The comparative analysis of the amino acid sequences of p58, p70, and p140 molecules revealed the existence of two cysteins proximal to the transmembrane region, only in the amino acid sequence of p140 molecules.     

Central sleep apnea

A central sleep apnea is the absence of respiratory effect, and, thus, the absence of airflow during sleep. Central hypopnea, a related disorder, is also discussed. The sensory component of central sleep apnea; defects involving the integrative and executive neurons; non-neurologic causes of central sleep apneas, including chronic obstructive pulmonary disease and congestive heart failure; diagnosis; treatment; and other topics are reviewed in detail.     

Novel diterpenoid diacylglycerols from marine molluscs: potent morphogens and protein kinase C activators

Five novel 1,2-sn-diacylglycerols with diterpenoid acyl moieties in the sn-1 position were isolated and characterized, together with the corresponding 1,3-sn-diacylglycerols, from three species of dorid nudibranchs molluscs. Their potent activity as morphogens in vivo in the Hydra tentacle regeneration assay and their parallel activity as activators of rat brain protein kinase C (PKC) in vitro are reported here. Our findings promote the use of these compounds as useful molecular probes for both in vivo and in vitro studies on the participation of PKC in cell development.