Crosslinked polyimide foams derived from poly(imidepropylene oxide) copolymers

A new route for the synthesis of high glass transition temperature, thermally stable polymer foams has been developed, using compositionally asymmetric microphase-separated block copolymers where the minor component (poly(propylene oxide)) is thermally labile and the major component (polyimide) is thermally stable. The minor component decomposes to low molecular weight species upon heating, and the decomposition products diffuse out of the film, leaving behind pores embedded in a matrix of the thermally stable component. In this study, the polyimide block was crosslinked with ethynyl functionalities to obtain a stable porous structure. The decomposition of the propylene oxide in the block copolymer was studied by thermogravimetric, dynamic mechanical and thermomechanical analyses. Mild conditions were required to avoid rapid depolymerization of the propylene oxide and plasticization of the polyimide matrix. The foams showed pore sizes with diameters up to a micrometer in size as well as the expected reduction in the mass density.     

Molecular typing of the etiologic agent of human granulocytic ehrlichiosis

The p44 gene of the agent of human granulocytic ehrlichiosis (aoHGE) encodes a 44-kDa major outer surface protein. A technique was developed for the typing of the aoHGE based on the PCR amplification of the p44 gene followed by a multiple restriction digest with HindIII, EcoRV, and AspI to generate restriction fragment length polymorphism patterns. Twenty-four samples of the aoHGE were collected from geographically dispersed sites in the United States and included isolates from humans, equines, canines, small mammals, and ticks. Six granulocytic ehrlichiosis (GE) types were identified. The GE typing method is relatively simple to perform, is reproducible, and is able to differentiate among the various isolates of granulocytic ehrlichiae in the United States. These characteristics suggest that this GE typing method may be an important epizootiological and epidemiological tool.     

Reliability and feasibility of a near patient test for C-reactive protein in primary care.

BACKGROUND: The applications of new diagnostic technologies such as near patient tests are relevant to the further development and potential of primary care. Through their use, doctors in the community may increase the accuracy of their diagnoses and improve their ability to monitor disease. A reliable indicator of disease activity in various clinical conditions is C-reactive protein (CRP) and a near patient test for this is now available, although there is little information on its use outside hospitals. AIM: A study was set up to evaluate the feasibility of using a novel near patient test for CRP in primary care to validate the results against the laboratory "gold standard' for CRP (Beckman Array) and to compare results with the usual inflammation test used in general practice. METHOD: Prospective recording of CRP as a near patient test on an "intention to investigate' basis, with validation of results against the Beckman Array system for CRP and hospital laboratory erythrocyte sedimentation rate results, in six general medical practices in Birmingham. Main outcome measures were change in local laboratory usage, characteristics of patients chosen for testing, use of quality control, and comparison of readings with results from the same sample sent to an independent laboratory. RESULTS: Tests of CRP levels were rarely requested before the study was undertaken. During the 3-month study period, 181 near patient tests were carried out, 146 (81%) to establish a diagnosis and the remainder for disease monitoring. Out of the tests, 67% were performed by general practitioners, mostly during the consultation itself. Using a cut-off level of 10 mg I-1, the near patient test and the Beckman Array gave results which agreed in 84% of cases. The sensitivity and specificity of the near patient test results were 97 and 79%, respectively. The predictive value of a positive result was 59% and that of a negative result was 99%. Cohen's Kappa was 62% and the overall mean bias for results in the range of the test was 6.11 mg I-1 (SE = 3.07 mg I-1). Each test took 6 min on average to perform, including all preparations, blood letting, performing the test and averaging the time for quality control estimations. The cost per test averaged pounds 1.72, rising to pounds 4.17 including labour, capital costs, quality controls and consumables (general practitioner performing the assay at average frequency found in this study). CONCLUSIONS: Measurement of CRP is rarely used in primary care and awareness of its value could be raised. This near patient test proved feasible for use by general practitioners and practice nurses. Its reliability compared with a laboratory result was satisfactory overall, and excellent with adequate operator technique.     

Methoxsalen stimulates electrogenic Cl- secretion in the mouse jejunum

We used the short-circuit current (I(sc)) and patch-clamp techniques to investigate the effects of methoxsalen (MTX) on the electrogenic Cl- secretion of the mouse jejunum. MTX stimulated a sustained increase in Isc that was dose dependent. Bumetanide inhibited MTX-stimulated Isc in a dose-dependent manner consistent with activation of Cl- secretion. MTX failed to stimulate I(sc) following maximal activation of the cAMP pathway by forskolin, but did increase Isc after a submaximal dose of forskolin. Glibenclamide, a blocker of the cystic fibrosis transmembrane conductance regulator (CFTR), reduced the MTX-stimulated increase of Isc by 59 +/- 6%. The cAMP-dependent K+ channel blocker 293B did not alter the MTX-activated I(sc); however, clotrimazole, an intermediate Ca2(+)-activated K+ channel (IK(Ca)) blocker, reduced the MTX-stimulated I(sc). MTX did not alter Na(+)-glucose cotransport across the mouse jejunum. In cell-attached membrane patches, MTX increased the open probability of the basolateral IK(Ca) channel of isolated crypts. These data suggest that the CFTR and IK(Ca) channels participate in the MTX-activated, sustained Cl- secretory response of the mouse jejunum.     

Translocation (14;19) in acute biphenotypic leukemia

Translocation (14;19)(q32;q13.1) is an acquired chromosomal rearrangement that has been associated with chronic lymphocytic leukemia of B-cell phenotype frequently progressing to lymphoma. Molecular analysis suggests that the translocation involves the immunoglobulin heavy chain gene on chromosome 14 and the BCL3 oncogene on chromosome 19. We present the first case of t(14;19) in a patient with acute leukemia. Correlation of detailed cytogenetic and molecular genetic studies, cell surface marker analysis, cytochemistry, and electron microscopy indicated that the leukemic cells were biophenotypic, with characteristics consistent with both myeloid and B-lineage lymphoid differentiation.     

Tandem insertion sequence-like elements define the expression site for variable antigen genes of Borrelia hermsii.

The spirochete Borrelia hermsii avoids the immune response of its mammalian host through multiphasic antigenic variation. Serotype specificity is determined by variable antigens, Vmp proteins, in the outer membrane. Through nonreciprocal recombination between linear plasmids, a formerly silent vmp gene replaces another vmp gene downstream from a common expression site. To further characterize this activating site, we determined the nucleotide sequence of 6.9 kb of the common upstream expression region of strain HS1 of B. hermsii. Preceding the vmp gene promoter and a poly(dT.dA) run were three imperfectly repeated segments of 2 kb. Each of the 2-kb segments contained 1-kb elements with inverted repeats of approximately 0.2 kb each at their termini. The potential of the 1-kb elements to form stem-and-loop structures was demonstrated by heteroduplex analysis. There was no evidence of the presence of the elements elsewhere in the genome of B. hermsii. One or more of these elements may confer the unidirectionality that characterizes vmp gene switches.     

A computer model for the study of breast cancer

A computer model was designed as a relational database to assess breast cancer screening in a cohort of women where the growth and development of breast cancer originates with the first malignant cell. The concepts of thresholds for growth, axillary spread, and distant sites are integrated. With tumor diagnosis, staging was performed that includes clinical and sub-clinical states. The model was parameterized to have staging characteristics similar to data published by the Surveillance, Epidemiology, and End-Results (SEER) Program. Validation was accomplished by comparing simulated staging results with non-SEER sources, and simulated survival with independent clinical survival data.