Evolution of weak discontinuities in a radiating magnetofluid

Summary The evolutionary behaviour of first and higher order weak discontinuities in a radiating magnetofluid is analysed using the singular surface theory. The fluid is assumed to be a neutral gas with infinite electrical conductivity and it is penetrated by a magnetic field normal to the propagation direction of the wave front. The effects of radiative heat transfer are treated by the use of a differential approximation for a grey gas including effects of radiative heat flux, pressure and energy density.     

Serial sectioning of sentinel nodes in patients with breast cancer: a pilot study

Bone morphogenetic protein (BMP) has the ability to induce ectopic bone, while the action of transforming growth factor beta (TGF beta) is to stimulate proliferation of osteoblasts and chondrocytes as well as the production of extracellular matrix. The aim of the present study was to study their synergistic actions in bone formation. Three kinds of complexes, recombinant human BMP2 (rhBMP2), TGF beta and rhBMP2/TGF beta in ceramic bovine bone (CBB), were made and then implanted into the thigh muscle pouches of mice. The histological reactions of the implanted areas were studied at intervals of 3, 5, 7, 14 and 21 days. The results showed that, except for the implants with TGF beta alone, both rhBMP2 and rhBMP2/TGF beta implants exhibited new ectopic bone formation. The morphometric study revealed that the quantity of newly formed bone induced by rhBMP2/TGF beta was obviously greater than by rhBMP2 alone. These results indicate that TGF beta in combination with BMP may enhance formation of ectopic bone.     

Cowpea cooking characteristics as affected by micronisation temperature: a study of the physicochemical and functional properties of starch

Bechuana white cowpeas were micronised to three temperatures (130, 153 and 170 °C). Cooking properties of the cowpea seeds and the role of starch‐related properties were studied. In all cases, micronisation significantly reduced the cooking time and thus the time required for the cowpea seeds to attain a suitably soft texture. This was attributed in part to the significant improvement in rate of water absorption during cooking and starch pre‐gelatinisation, as evidenced by loss of birefringence and increased susceptibility of the cowpea starch to α‐amylase digestion. However, micronisation to 170 °C resulted in a severe deterioration in pasting properties of the cowpea flour, possibly due to starch depolymerisation and/or amylose‐associated crosslinking. Owing to these changes, cowpea seeds micronised to 170 °C required a longer cooking time than the other two micronised samples. Flour prepared from cowpea seeds micronised to 170 °C may have limited starch functionality. Copyright © 2006 Society of Chemical Industry     

Histo-pathological evaluation of response to 6 and 12 months of interferon alpha therapy

BACKGROUND AND AIMS: Interferon-alfa (IFN-alfa) has recently been introduced for chronic C hepatitis treatment; however, the response rate is merely 25-50%. The aims of this follow-up study were to compare the efficacy of 6 and 12-month IFN-alfa treatment via liver biopsy scores and to evaluate the correlation with the biochemical response. PATIENTS AND METHODS: 20 chronic C hepatitis patients were studied. 10 patients received IFN-alfa therapy for 6 months, and 10 for 12 months (3 million units three times a week). Liver biopsy material was taken before and after therapy. RESULTS: There was a significant serum alanine aminotransferase (ALT) level improvement in both groups, but a significant histological improvement in necroinflammatory activity (grade) occurred only in the 12-month group. The Chevallier stage scores demonstrated a significant progression in both groups. CONCLUSIONS: 12-month IFN-alfa treatment affords a better response in the liver histology grade and serum ALT level, but not the stage; a normal ALT does not guarantee hepatitis inactivity. Liver biopsies appear indispensable for monitoring the fibrotic changes in chronic C hepatitis.     

The influence of gastrin and/or cholecystokinin antagonists on the proliferation of three human astrocytic tumor cell lines

We have investigated the potential role of gastrin in the regulation of cell growth in human astrocytic tumors. To this end we have used synthetic analogs of gastrin and cholecystokinin (CCK) which behave as gastrin and/or CCK antagonists, e.g. compounds JMV-97, JMV-209 and JMV-179. Their effects on astrocytic tumor cell proliferation was investigated by the use of the colorimetric MTT assay. The in vitro biological models used in the present study included the SW1088, U87 and U373 astrocytic tumor cell lines. The results demonstrated marked influence of gastrin and CCK antagonists in the regulation of astrocytic tumor growth. This suggests that gastrin and/or CCK antagonists might be tested in experimental glioblastoma.     

Nociceptive integration in the rat spinal cord: role of non-linear membrane properties of deep dorsal horn neurons

Deep dorsal horn neurons (DHNs) involved in nociception can relay long-lasting inputs and generate prolonged afterdischarges believed to enhance the transfer of nociceptive responses to the brain. We addressed the role of neuronal membrane properties in shaping these responses, by recording lamina V DHNs in a slice preparation of the rat cervical spinal cord. Of 256 neurons, 102 produced accelerating discharges in response to depolarizing current pulses, whereas the other neurons showed spike frequency adaptation. Two mechanisms mediated the firing acceleration: a slow inactivation of a K+ current expressed upon activation of the neuron from hyperpolarized holding potentials, and the expression of a regenerative plateau potential activating around resting membrane potential. The increase in firing frequency was much stronger when sustained by the plateau potential (71 DHNs, 28%). A few neurons produced adaptation and both types of acceleration, in different membrane potential domains, showing that the firing pattern of a deep DHN is not a rigid characteristic. Plateau potentials could be elicited by stimulation of nociceptive primary afferent fibres. The bistability associated with plateau potentials permitted afterdischarges. Because plateau potentials had slow activation kinetics and were voltage-dependent, the neurons had non-linear input-output relationships in both the amplitude and time domains. Nociceptive primary afferent stimulation elicited intense and prolonged responses in plateau-generating DHNs, while brief bursts of spikes were evoked otherwise. These results indicate that in a population of deep DHNs, intense firing and prolonged afterdischarges in response to nociceptive stimulation depend on non-linear intrinsic membrane properties.     

Cracking of concrete structures due to imposed strains with regard to design of reinforcement

The principles for control of cracking in concrete structures due to imposed strain are investigated in this paper. The effects of uniform and non-uniform cooling and shrinkage are studied in medium-thick walls with regard to the amount of reinforcement necessary to distribute cracks. The influence of reinforcement on the behavior after the first crack is investigated, in particular its ability to reduce crack widths. The restraint force is significantly reduced for non-uniformly distributed imposed strain due to softening and cracking in the concrete. The amount of minimum reinforcement needed to distribute cracks is therefore significantly smaller for imposed strain in the form of drying shrinkage than for thermal imposed strain. Crack reinforcement is most effective for structures with large dimensions in the direction of external restraint.     

Patients with absolutely immotile spermatozoa and intracytoplasmic sperm injection

The microinjection of completely immotile spermatozoa may impair the outcome of intracytoplasmic sperm injection (ICSI). Eleven couples underwent an initial ICSI cycle with 100% immotile freshly ejaculated spermatozoa. Two-pronuclear fertilization ensued in 18 of 145 (12.4%) successfully injected oocytes. None of these cycles resulted in a pregnancy. Nine couples underwent ICSI in subsequent cycles (n = 16). Ejaculated spermatozoa were injected in 15 cycles and testicular spermatozoa in one cycle. In 10 of the 15 cycles, motile spermatozoa were available at the time of injection. Motile testicular spermatozoa could also be injected. In the subsequent cycles, 91 of 176 (51.7%) successfully injected oocytes fertilized normally and four patients became pregnant. In the subsequent cycles where again immotile spermatozoa had to be injected no pregnancies occurred. In four subsequent cycles embryo cryopreservation was carried out. After replacement of two frozen-thawed embryos one additional pregnancy was obtained. In all, five healthy infants were born. It has been ascertained that motile spermatozoa can be detected either in repeated ejaculates or after testicular biopsy. The causes of total asthenozoospermia are variable and the problem is a sporadic rather than a permanent condition.     

Mechanical spectroscopy of thin layers of PPV polymer on Si substrates

The vibrating reed technique with electro“static” excitation and optical detection has been applied to investigate thin layers of poly-phenylene-vinylene, deposited by spin coating onto microfabricated Si cantilevers, during temperature cycling programs between 90 and 540 K at a rate of 1 K/min. From the vibration frequencies the Young’s modulus of the film can be estimated to be about 10 MPa at room temperature in the precursor phase (if prepared from a solution in toluene), which increases by conversion to the conjugate bonded polymer to about 50 MPa. The temperature dependence of internal friction reveals the processes of γ relaxations (crankshaft motion of side branches in the precursor) and β-relaxation (movements of a few monomer blocks in the polymer chain), as well as peaks indicating the structural transformations during conversion, and possibly a glass transition in the amorphous precursor phase. After conversion only the β-relaxation persists.