Vascular rejection post heart transplantation is associated with positive flow cytometric cross-matching

28 isolates of canine parvovirus type-2 (CPV-2) were obtained from dogs with hemorrhagic gastroenteritis in Italy. The antigenic structure of CPV-2 isolates was characterized, using four discriminating monoclonal antibodies. In addition, four vaccinal strains were examined. Similar to reports from Australia and the United Kingdom, a much higher prevalence of CPV-2a (25/28 isolates) was observed than the other variant type, CPV-2b (3/28 isolates). DNA fragments (2.2 kbp) of representative strains of CPV-2, CPV-2a and CPV-2b were amplified by the polymerase chain reaction (PCR) and the products were digested by the restriction enzymes (RE) RsaI, HpaII, HindIII and PvuII. The RvaI enzyme allows the differentiation of CPV-2 from CPV-2a and CPV-2b.     

A comparison of gene organization in the zwf region of the genomes of the cyanobacteria Synechococcus sp. PCC 7942 and Anabaena sp. PCC 7120

The region of the genome encoding the glucose-6-phosphate dehydrogenase gene zwf was analysed in a unicellular cyanobacterium, Synechococcus sp. PCC 7942, and a filamentous, heterocystous cyanobacterium, Anabaena sp. PCC 7120. Comparison of cyanobacterial zwf sequences revealed the presence of two absolutely conserved cysteine residues which may be implicated in the light/dark control of enzyme activity. The presence in both strains of a gene fbp, encoding fructose-1,6-bisphosphatase, upstream from zwf strongly suggests that the oxidative pentose phosphate pathway in these organisms may function to completely oxidize glucose 6-phosphate to CO2. The amino acid sequence of fructose-1,6-bisphosphatase does not support the idea of its light activation by a thiol/disulfide exchange mechanism. In the case of Anabaena sp. PCC 7120, the tal gene, encoding transaldolase, lies between zwf and fbp.     

Scientific role of German ophthalmology in the European telecommunication project OPHTEL]

We examined 21 patients aged 5 months to 19 years, on a 1.5 T magnet. T1-weighted spin-echo images, proton density and T2-weighted images with spin-echo and turbo spin-echo sequences, and contrast-enhanced magnetization transfer (MT) T1-weighted images were obtained in all cases. MT T1-weighted images were performed before injection in 9 patients. Subependymal nodules were found in 14, and cortical and subcortical tubers in 20 of the 21 patients. MT T1-weighted images showed tubers and subependymal nodules as higher signal than normal gray matter and revealed more tubers than conventional sequences in 11 cases. High signal intensity lesions of the white matter were found in 19 patients but were seen only on MT images in 9 cases. When MT images both before and after injection were available, tubers and white matter lesions were more easily recognised on unenhanced MT images because of their higher contrast.     

Carbon monoxide and water vapor contamination of compressed breathing air for firefighters and divers

Compressed breathing air, used in self-contained breathing apparatus (SCBA) by firefighters and other categories of workers as well as by recreational and commercial divers, is prepared with the aid of high-pressure compressors operating in the range of 5000 psig. There have been reports of unexplained deaths of SCUBA divers and anecdotal accounts of decreased time to exhaustion in firefighters using SCBAs. Compressed breathing air has been found to contain elevated levels of carbon monoxide (CO) and water vapor that are consistent with carboxyhemoglobin (COHb) poisoning and freezing of the user's regulator on the breathing apparatus. The Coburn-Forster-Kane equation (CFK equation) was used to estimate COHb levels at rest and at maximum exercise when exposed to different levels of CO in contaminated breathing air. The results demonstrated that, at maximum exercise, the COHb ranged from 6.0 to 17% with the use of 1 to 4 SCBA cylinders contaminated by 250 ppm CO. Standard operating procedures have been developed at the Montreal Fire Department to minimize the risk of compressed breathing air contamination. Results of the quality analysis/quality control program indicate that implementation of these procedures has improved the quality of the compressed breathing air. Recommendations are made for improvement of the air testing procedures mandated by the Canadian CAN3 180.1-M85 Standard on Compressed Breathing Air and Systems.     

Optimization of a schottky barrier mixer diode in the submillimeter wave region

We have designed a mixer Schottky barrier diode (SBD) for use in the submillimeter wave region with a structure optimized for minimum noise temperature. The dependence of mixer noise temperature upon thickness and doping density of the epitaxial layer and diode diameter of SBDs was simulated within the framework of existing theories. Special care was taken to formulate the SBD current-voltage and capacitance-voltage relations in a way that correctly describes the behavior of real SBDs.     

Synaptically evoked glutamate transport currents may be used to detect the expression of long-term potentiation in cerebellar culture

Cerebellar long-term potentiation (LTP) is a use-dependent increase in the strength of the granule cell-Purkinje neuron synapse that occurs after brief stimulation of granule cell axons at 2-8 Hz. Previous work has shown that cerebellar LTP also may be seen when synaptic currents are evoked in granule cell-glial cell pairs in culture. This finding suggests a model in which cerebellar LTP is expressed presynaptically and therefore may be detected by either neuronal or glial postsynaptic cells. However, synaptic currents evoked in both granule cell-glial cell pairs and granule cell-Purkinje neuron pairs in culture are mediated primarily by alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptors, raising the possibility that cerebellar LTP might be expressed postsynaptically in both glial cells and Purkinje neurons in a similar manner. To address this question, glutamate transport currents were recorded in granule cell-glial cell pairs in culture by pharmacological isolation. These currents were increased by substitution of internal Cl with NO3 and were blocked by -pyrrolidine-2,4-dicarboxylate, both characteristics of the major cloned Bergmann glial cell glutamate transporter, EAAT1. After acquisition of baseline responses, LTP of isolated transport current was evoked by stimulation at 4 Hz (100 pulses) and could be blocked by removal of external Ca during this stimulation. The expression of LTP was associated with a decrease in the rate of synaptic failures and a decrease in the degree of paired-pulse facilitation. These findings, when taken together with the previous observation that both Purkinje neuron and glial AMPA/kainate responses can be used to detect cerebellar LTP, strongly suggest that the expression of cerebellar LTP is, at least in part, presynaptic. This strategy should also be useful in illuminating the locus of expression of other model systems of information storage such as hippocampal LTP/long-term depression.     

Structure of nitric oxide synthase oxygenase dimer with pterin and substrate

Crystal structures of the murine cytokine-inducible nitric oxide synthase oxygenase dimer with active-center water molecules, the substrate L-arginine (L-Arg), or product analog thiocitrulline reveal how dimerization, cofactor tetrahydrobiopterin, and L-Arg binding complete the catalytic center for synthesis of the essential biological signal and cytotoxin nitric oxide. Pterin binding refolds the central interface region, recruits new structural elements, creates a 30 angstrom deep active-center channel, and causes a 35 degrees helical tilt to expose a heme edge and the adjacent residue tryptophan-366 for likely reductase domain interactions and caveolin inhibition. Heme propionate interactions with pterin and L-Arg suggest that pterin has electronic influences on heme-bound oxygen. L-Arginine binds to glutamic acid-371 and stacks with heme in an otherwise hydrophobic pocket to aid activation of heme-bound oxygen by direct proton donation and thereby differentiate the two chemical steps of nitric oxide synthesis.     

HLA-B27-restricted antigen presentation in the absence of tapasin reveals polymorphism in mechanisms of HLA class I peptide loading

Tapasin is a resident ER protein believed to be critical for antigen presentation by HLA class I molecules. We demonstrate that allelic variation in MHC class I molecules influences their dependence on tapasin for peptide loading and antigen presentation. HLA-B*2705 molecules achieve high levels of surface expression and present specific viral peptides in the absence of tapasin. In contrast, HLA-B*4402 molecules are highly dependent upon human tapasin for these functions, while HLA-B8 molecules are intermediate in this regard. Significantly, HLA-B*2705 like HLA-B*4402, requires tapasin to associate efficiently with TAP (transporters associated with antigen processing). The unusual ability of HLA-B*2705 to form peptide complexes without associating with TAP or tapasin confers flexibility in the repertoire of peptides presented by this molecule. We speculate that these properties might contribute to the role of HLA-B27 in conferring susceptibility to inflammatory spondyloarthropathies.     

Stem cell factor enhances the adhesion of AML cells to fibronectin and augments fibronectin-mediated anti-apoptotic and proliferative signals

Acute myeloid leukaemia (AML) cells express the SCF receptor c-kit (CD117) on their cell surface and demonstrate enhanced adhesion to fibronectin (FN) following exposure to stem cell factor (SCF). Increased adhesion occurs within 5 min, is dose dependent, and persists beyond 2 h. Baseline and enhanced adhesion occur through the surface FN receptor very late antigen-5 (VLA-5, CD49e/CD29) which is expressed by AML cells. Unstimulated AML cells exposed to FN undergo less apoptosis than controls (inhibition 22.5 +/- 7.0%, P = 0.02, n = 8). Exposure to SCF alone without FN also inhibits AML cell apoptosis (by 19.0 +/- 7.7% compared to controls, P = 0.06, n = 8). Simultaneous exposure to SCF and FN increases the inhibition of AML cell apoptosis to 37.8 +/- 7.9% (P = 0.005 compared to control, P = 0.04 compared to FN alone, P = 0.06 compared to SCF alone) demonstrating that SCF not only enhances the propensity of AML cells to adhere to FN, but also results in an additive survival benefit following FN contact. Some but not all the reduction in apoptosis is mediated through VLA-5. The combination of SCF and FN also affects proliferation, resulting in a synergistic enhancement of AML cell proliferation in half the cases studied. When normal CD34+ human haemopoietic progenitors were studied, FN had little effect on their apoptosis and failed to enhance the anti-apoptotic effect of SCF. It did, however, synergise with SCF in promoting CD34+ cell proliferation. Exposure of AML cells to SCF and FN, both of which can be found in high concentration in the bone marrow stroma, inhibits apoptosis. Cytokines and extracellular matrix proteins augment each others' effects since SCF enhances adhesion to fibronectin, which in turn augments the survival signal delivered by the cytokine alone. Cytokine and adhesion receptors can combine to affect cell characteristics including proliferation and survival.     

Gallstones and isoflurane hepatitis

OBJECTIVES: To assess the level of satisfaction of physicians in provincial psychiatric hospitals with Review Boards (RBs) regarding Civil Commitment Certificates (CCCs), Certificates of Incompetence (COIs), and Treatment Orders (TOs). METHOD: A total of 200 survey questionnaires were distributed to physicians in provincial psychiatric hospitals. Ninety surveys (completed by 25 females, 45 males, and 20 unknown gender) were returned, representing a 45% return rate. Because of their assignments (for example, outpatient department), not all physicians were involved with RBs, and the return rate is likely to have been influenced by this factor. RESULTS: Physician satisfaction rates of 58.2% for CCCs, 66.7% for COIs, and 70.0% for TOs were obtained. Stepwise multiple regression analysis showed that the level of physician satisfaction with RBs for CCCs was predicted best (44.7% of variance) by physician level of comfort with certification and years of institutional affiliation. Qualitative physician responses revealed 3 major themes: patient-related issues, physician-related issues, and RB structure- and process-related issues. CONCLUSIONS: Strategies that increase physician comfort level with RBs and changes in the medicolegal structure and process are discussed. A similar survey of patients and RB members is recommended.