Acoustic emission analysis of human bones within the scope of clinical diagnosis

Fractures occurring in human bones produce an acoustic signal, analysis of which permits an evaluation of its source. In the industrial setting acoustic emission analysis (AEA) is used to non-invasively monitor the function of stressed technical systems or parts of systems. During servicing and monitoring of technical systems, acoustic signals emitted by cracks or material deformation are located with the aid of a few acoustic sensors and evaluated for risk-identification purposes. With appropriate technology, therefore, both cortical and trabecular bone can be monitored by acoustic emission analysis. A search is currently ongoing for suitable acoustic technology capable of assessing the extent and location of bone defects and predicting associated risks of fractures occurring. In the present study a system for the measurement and analysis of acoustic emission is described which permits the measurement and analysis of acoustic signals obtained from processed and fresh human and porcine femora. In slightly modified form this system was then used to assess the type and extent of acoustic emission obtained from explanted human femora exposed to cyclical torsional loading until fracture occurred.     

Ginzburg-Landau analysis of first-order transitions of elastically strained superconducting tin whiskers

A recently developed Ginzburg-Landau-type equation has been used to analyze measurements of the effect of stress on first-order superconducting transitions of tin whiskers. Assumptions were made as to the temperature dependence of the effective penetration depth and the validity of simple similarity. The analysis is in terms of three parameters of bulk tin. The critical temperature was measured directly at each stress. The other two parameters, namely the zero-temperature values of the critical field and the effective penetration depth, were computed at each stress by an optimization procedure. Combination of the three parameters gives a reasonable estimate of the average Fermi velocity but cannot reveal if this is stress-dependent. The critical temperature is known to increase linearly with stress along the tetragonal axis and quadratically at right angles to it, and the critical magnetic field is found to increase similarly at a slightly higher rate. The results are compared with those obtained for the same whiskers in the second-order region, and also with other measurements of related properties, such as the change in length of bulk single crystals at the superconducting transition.     

Cloning and structure of the gene encoding the human N-methyl-D-aspartate receptor (NMDAR1)

The complete gene encoding the human N-methyl-D-aspartate receptor subunit NR1 (NMDAR1) has been isolated on a single cosmid clone. The gene is composed of 21 exons distributed over a total length of about 31 kb. More than 24 kb were sequenced. Exons 4, 20 and 21 are identical in their amino-acid sequence to those exons that are subject to alternative splicing in rat, indicating that all eight NMDAR1 isoforms found in rat will also be expressed in the human brain. Computer analysis of the pre-mRNA sequence revealed no secondary structures stable enough to explain alternative splicing. We suggest that cell-specific factors control expression of different isoforms. The promoter region contains two perfect copies of the recognition sequence for the Drosophila even-skipped protein, indicating that the developmentally regulated expression of NMDAR1 is controlled by a homeobox protein. The complete cosmid clone covering NMDAR1 was mapped to chromosome 9q34.3-qter by fluorescent in situ hybridization (FISH). The telomeric location is supported by an imperfect (CA)n repeat homologous to a subtelomeric repeat on chromosome 16p.     

Antineoplastic activity of the thioether lysophospholipid derivative BM 41.440 in vitro

Thioether lysophospholipid derivatives (TLP) inhibited the in vitro uptake of [³H]thymidine into blasts of eight leukemias and cells of 12 different solid tumors of human origin. This effect correlated with trypan blue dye exclusion, which was used to assess cell damage. Cytostatic and cytotoxic effects of TLP were dependent on dosage and incubation time. Destruction of leukemic blasts was completed with >5 μg/ml after an incubation of >48 hr, but 10 to 20 μg/ml were necessary in solid tumors. Ester-linked 2-lysophosphatidylcholine was ineffective in the same dose range, which points to the requirement of the alkyl moiety insn-1 and a stablesn-2 substitution of the molecule for the antineoplastic effect. To assess putative antileukemic selectivity, the cytotoxicity (trypan blue dye exclusion) of TLP was compared in human cell samples of 19 non-neoplastic bone marrows and 9 leukemias. Results revealed a significantly higher activity of the TLP BM 41.440 in leukemic blasts.     

Magnetization of Materials Used in Cryostats

We measure the magnetic susceptibility of a group of materials commonly used in the construction of low temperature cryostats. These materials are considered non-magnetic at room temperature. We use a variable temperature susceptometer to measure samples at temperatures between 2.0 K and 12.0 K and at magnetic fields between 0.25 Tesla and 4 Tesla. The samples we use include Aluminum, Beryllium Copper, fused silica, Grafoil, stainless steel, filled and unfilled epoxy, Macor, polycarbonate, aerogel, silver powder, Teflon, and Vespel. We present plots of the magnetization vs. temperature and field, and a table of the parameters to a fitting function which can be used to interpolate the data.     

The effects of pre-exercise starch ingestion on endurance performance

This study compared the physiological responses and performance following the ingestion of a waxy starch (WS), resistant starch (RS), glucose (GL) and an artificially-sweetened placebo (PL) ingested prior to exercise. Ten college-age, male competitive cyclists completed four experimental protocols consisting of a 30 min isokinetic, self-paced performance ride preceded by 90 min of constant load cycling at 66% VO2max. Thirty min prior to exercise, they ingested 1 g.kg-1 body weight of GL, WS, RS, or PL At rest, GL elicited greater (p < 0.05) serum glucose and insulin responses than all other trials. During exercise, however, serum glucose, insulin, blood C-peptide and glucagon responses were similar among trials. The mean total carbohydrate oxidation rates (CHOox) were higher (p < 0.05) during the GL, WS, and RS trials (2.59 +/- 0.13, 2.49 +/- 0.10, and 2.71 +/- 0.15 g.min-1, respectively) compared to PL (2.35 +/- 0.12 g.min-1). Subjects were able to complete more work (p < 0.05) during the performance ride when they ingested GL (434 +/- 25.2 kj) or WS (428 +/- 22.5 kj) compared to PL (403 +/- 35.1 kj). They also tended to produce more work with RS ingestion (418 +/- 31.4 kj), although this did not reach statistical significance (p < 0.09). These results indicate that preexercise CHO ingestion in the form of starch or glucose maintained higher rates of total carbohydrate oxidation during exercise and provided an ergogenic benefit during self-paced cycling.     

Electronic properties of electron-doped Nd2−x Ce x CuO4−δ, Sr1−x Nd x CuO2−δ, and Hole-Doped Nd1.4Ce0.2Sr0.4CuO4−δ studied by photoelectron spectroscopy

We present investigations on the electronic structure of the recently discovered, electron-doped infinite-layer compound Sr_1?xNd_xCuO_2?δ (T _c≈40K) by means of photoelectron spectroscopy with synchrotron radiation. This system is compared with the two closely related cuprates Nd_2?xCe_xCuO_4?δ (electron doped) and Nd_1.4Ce_0.2Sr_0.4CuO_4?δ (hole doped). Valence band spectra in the Cu 3p→3d resonance are interpreted in terms of CuO₄ (n-doped compounds) and CuO₅ (p-doped system) cluster models. From our calculations we find a considerably higher Cu3d Coulomb correlation for the electron-doped compounds as well as a very low Cu-O hybridization for the infinite-layer system. Partial Nd spectra of Sr_0.85Nd_0.15CuO_2?δ show the Nd dopants to be trivalent, thus confirming the infinite-layer compound to be electron doped. Analysis of partial Nd valence bands and magnetic susceptibilities of Nd_2?xCe_xCuO_4?δ and Nd_1.4Ce_0.2Sr_0.4CuO_4?δ gives very similar electronic parameters and antiferromagnetic correlations between Nd spins for both cuprates.     

Coronary artery bypass surgery during pregnancy

A 32-year-old woman, in the 22nd week of pregnancy, underwent emergency coronary artery bypass grafting to the left anterior descending artery (LAD). She had suffered an acute myocardial infarction 10 days previously, and continued to suffer from intractable angina pectoris afterwards. Cardiac catheterization revealed spontaneous dissection of the LAD. The left internal mammary artery was used to bypass the LAD, and the operation was performed on a beating heart without the use of cardiopulmonary bypass. The patient's recovery was uneventful, and ultrasound examination and pulse monitoring of the fetus were both normal. She subsequently gave birth to a healthy term baby. To our knowledge this is the second report of coronary artery bypass surgery performed successfully in a pregnant woman. We believe the unique surgical approach avoided the risk of cardiopulmonary bypass to the fetus and placenta.     

Development of an HSV-based vector for the treatment of Parkinson's disease

The restricted pattern of neurodegeneration seen in Parkinson's disease, and the identification of trophic factors that prevent toxin-induced degeneration of dopaminergic neurons, has spurred research into potential gene therapy for this disease. Herpes simplex virus (HSV-1) is a neurotrophic virus which naturally establishes latency in neurons. HSV-based vectors have been demonstrated to transfer and transiently express transgenes in neurons in brain in vivo. Recent experiment have shown that deletion of multiple immediate-early HSV genes reduces the potential cytotoxicity of these vectors, and in addition results in altered patterns of transgene expression that may allow for long-term expression required for human gene therapy applications.