Kinetic analysis of vascular marker distribution in perfused rat livers after regeneration following partial hepatectomy

Background/Aims: Liver clearance models are based on information (or assumptions) on solute distribution kinetics within the microvasculatory system, The aim was to study albumin distribution kinetics in regenerated livers and in livers of normal adult rats, Methods: A novel mathematical model was used to evaluate the distribution space and the transit time dispersion of albumin in livers following regeneration after a two-thirds hepatectomy compared to livers of normal adult rats. Outflow curves of albumin measured after bolus injection in single-pass perfused rat livers were analyzed by correcting for the influence of catheters and fitting a long-tailed function to the data. Results: The curves were well described by the proposed model. The distribution volume and the transit time dispersion of albumin observed in the partial hepatectomy group were not significantly different from livers of normal adult rats. Conclusions: These findings suggest that the distribution space and the transit time dispersion of albumin (CV2) is relatively constant irrespective of the presence of rapid and extensive repair. This invariance of CV2 implies, as a first approximation, a similar degree of intrasinusoidal mixing, The finding that a sum of two (instead of one) inverse Gaussian densities is an appropriate empirical function to describe the outflow curve of vascular indicators has consequences for an improved prediction of hepatic solute extraction.

Efficient transformation and regeneration of diverse cultivars of peanut (Arachis hypogaea L.) by particle bombardment into embryogenic callus produced from mature seeds

Peanut, one of the world's most important oilseed crops, has a narrow germplasm base and lacks sources of resistance to several major diseases. The species is considered recalcitrant to transformation, with few confirmed transgenic plants upon particle bombardment or Agrobacterium treatment. Reported transformation methods are limited by low efficiency, cultivar specificity, chimeric or infertile transformants, or availability of explants. Here we present a method to efficiently transform cultivars in both botanical types of peanut, by (1) particle bombardment into embryogenic callus derived from mature seeds, (2) escape-free (not stepwise) selection for hygromycin B resistance, (3) brief osmotic desiccation followed by sequential incubation on charcoal and cytokinin-containing media; resulting in efficient conversion of transformed somatic embryos into fertile, non-chimeric, transgenic plants. The method produces three to six independent transformants per bombardment of 10 cm(2) embryogenic callus. Potted, transgenic plant lines can be regenerated within 9 months of callus initiation, or 6 months after bombardment. Transgene copy number ranged from one to 20 with multiple integration sites. There was ca. 50% coexpression of hph and luc or uidA genes coprecipitated on separate plasmids. Reporter gene (luc) expression was confirmed in T-1 progeny from each of six tested independent transformants. Insufficient seeds were produced under containment conditions to determine segregation ratios. The practicality of the technique for efficient cotransformation with selected and unselected genes is demonstrated using major commercial peanut varieties in Australia (cv. NC-7, a virginia market type) and Indonesia (cv. Gajah, a spanish market type).

Gold(III) template synthesis of a pendant-arm macrocycle

Gold(III)-directed condensation of ethane-1,2-diamine with nitroethane and formaldehyde yielded the gold-coloured macrocyclic complex (cis-6,13-dimethyl-6,13-dinitro-1,4,8,11-tetraazacyclotetradecan-1-ido)gold(III) and the orange acyclic complex (1,9-diamino-5-methyl-5-nitro-3,7-diazanoran-3-ido)gold(III) in good yields. Dissolution in strongly acidic solution gave the colourless fully protonated complexes. The pendant nitro groups are disposed on the same side of the macrocycle in a cis geometry, as confirmed by crystal structure analysis. In both complexes the gold ion lies in a square-planar environment of four nitrogen donors, and the co-ordinate bond to the deprotonated amine is shorter than the remaining Au-N distances.

Feedforward contraction of transversus abdominis is not influenced by the direction of arm movement

Because the structure of the spine is inherently unstable, muscle activation is essential for the maintenance of trunk posture and intervertebral control when the limbs are moved. To investigate how the central nervous system deals with this situation the temporal components of the response of the muscles of the trunk were evaluated during rapid limb movement performed in response to a visual stimulus. Fine-wire electromyography (EMG) electrodes were inserted into transversus abdominis (TrA), obliquus internus abdominis (OI) and obliquus externus abdominis (OE) of 15 subjects under the guidance of real-time ultrasound imaging. Surface electrodes were placed over rectus abdominis (RA), lumbar multifidus (MF) and the three parts of deltoid. In a standing position, ten repetitions of shoulder flexion, abduction and extension were performed by the subjects as fast as possible in response to a visual stimulus. The onset of TrA EMG occurred in advance of deltoid irrespective of the movement direction. The time to onset of EMC activity of OI, OE, RA and MF varied with the movement direction, being activated earliest when the prime action of the muscle opposed the reactive forces associated with the specific limb movement. It is postulated that the non-direction-specific contraction of TrA may be related to the control of trunk. stability independent of the requirement for direction-specific control of the centre of gravity in relation to the base of support.

Molybdenum carbonyl complexes of pendant-arm polyazamacrocycles

Molybdenum hexacarbonyl reacted with the pendant-arm macrocycles 10-methyl-1,4,8, 12-tetraazacyclopentadecane-10-amine (L-1) and trans-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane-6, 13-diamine (L-2) in the absence of air to form complexes fac-[MoL1(CO)(3)] and [Mo2L2(CO)(8)] respectively. The mononuclear complex has the macrocycle bound in a tridentate manner, including the pendant primary amine, whereas the dinuclear complex exhibits a bridging bis(didentate) co-ordination mode, again involving the pendant primary amines. Structures have been defined by crystal structure analyses. The preferential binding of the pendant primary amines rather than additional secondary amines parallels similar behaviour observed earlier with some mercury(II) and rhodium(III) complexes, and points to the important general role of this pendant, despite being fused directly to the macrocyclic ring, in metal-ion binding.

CDKN2A is not the principal target of deletions on the short arm of chromosome 9 in neuroendocrine (Merkel cell) carcinoma of the skin

The majority of small-cell lung cancers (SCLCs) express p16 but not pRb, Given our previous study showing loss of pRb in Merkel cell carcinoma (MCC)/neuroendocrine carcinoma of the skin and the clinicopathological similarities between SCLC acid MCC, we wished to determine if this was also the case in MCC, Twenty-nine MCC specimens from 23 patients were examined for deletions at 10 loci on 9p and I on 9p. No loss of heterozygosity (LO H) was peen in 9 patients including 2 for which tumour and cell line DNAs were examined. Four patients had LOH for all informative loci on 9p, Ten tumours showed more limited regions of loss on 9p, and from these 2 common regions of deletion were determined, Half of all informative cases had LOH at D95168, the most telomeric marker examined, and 3 specimens showed loss of only D9S168, A second region (InFNA-D9S126) showed L0H in 10(44%) cases, and case MCC26 showed LOH for only D9S126, implicating genes centromeric of the CDKN2A locus. No mutations in the coding regions of p16 were seen in 7 cell lines tested, and reactivity to anti-p16 antibody was seen in all Il tumour specimens examined and in 6 of 7 cell lines from 6 patients. Furthermore, all cell lines examined reacted with anti-p 14' antibody, These results suggest that neither transcript of the CDKN2A locus is the target of deletions on 9p in MCC and imply the existence of tumour-suppressor genes mapping both centromeric and telomeric of this locus. (C) 2001 Wiley-Liss, Inc.

Parametric signal regeneration

We present an ultra-high bandwidth all-optical digital signal regeneration device concept utilising non-degenerate parametric interaction in a one-dimensional waveguide. Performance is analysed in terms of re-amplification, re-timing, and re-shaping (including centre frequency correction) of time domain multiplexed signals. Bandwidths of 10-100 THz are achievable. (C) 2001 Published by Elsevier Science B.V.

Callus induction and plant regeneration from broccoli (Brassica oleracea var. italica) for transformation

We evaluated the efficiency of callus induction and plantlet regeneration from hypocotyl explants of broccoli (Brassica oleracea var. italica). The cultivars were ‘Marathon’, ‘Greenbelt’, and ‘Shogun’. Transformation success was not affected by the presence of tobacco feeder-cell layers on the culture media. The frequency of shoot regeneration was greater from 10-d-old hypocotyls than from 14-d-old hypocotyls. Both ‘Marathon’ and ‘Greenbelt’ had higher potentials for tissue regeneration than did ‘Shogun’. We found that for transformation selection, the optimum concentration was either 50 mg/L kanamycin or 100 mg/L genetkin.

Deep and superficial fibers of the lumbar multifidus muscle are differentially active during voluntary arm movements

AB Study Design. A cross-sectional study was conducted. Objective. To determine the activity of the deep and superficial fibers of the lumbar multifidus during voluntary movement of the arm. Summary of Background Data. The multifidus contributes to stability of the lumbar spine. Because the deep and superficial parts of the multifidus are near the center of lumbar joint rotation, the superficial fibers are well suited to control spine orientation, and the deep fibers to control intervertebral movement. However, there currently are limited in vivo data to support this distinction. Methods. Electromyographic activity was recorded in both the deep and superficial multifidus, transversus abdominis, erector spinae, and deltoid using selective intramuscular electrodes and surface electrodes during single and repetitive arm movements. The latency of electromyographic onset in each muscle during single movements and the pattern of electromyographic activity during repetitive movements were compared between muscles. Results. With single arm movements, the onset of electromyography in the erector spinae and superficial multifidus relative to the deltoid was dependent on the direction of movement, but the onset in the deep multifidus and transversus abdominis was not. With repetitive arm movements, peaks in superficial multifidus and erector spinae electromyography occurred only during flexion for most subjects, whereas peaks in deep multifidus electromyography occurred during movement in both directions. Conclusions. The deep and superficial fibers of the multifidus are differentially active during single and repetitive movements of the arm. The data from this study support the hypothesis that the superficial multifidus contributes to the control of spine orientation, and that the deep multifidus has a role in controlling intersegmental motion. (C) 2002 Lippincott Williams & Wilkins, Inc.

Current concepts in central nervous system regeneration

A dictum long-held has stated that the adult mammalian brain and spinal cord are not capable of regeneration after injury. Recent discoveries have, however, challenged this dogma. In particular, a more complete understanding of developmental neurobiology has provided an insight into possible ways in which neuronal regeneration in the central nervous system may be encouraged. Knowledge of the role of neurotrophic factors has provided one set of strategies which may be useful in enhancing CNS regeneration. These factors can now even be delivered to injury sites by transplantation of genetically modified cells. Another strategy showing great promise is the discovery and isolation of neural stem cells from adult CNS tissue. It may become possible to grow such cells in the laboratory and use these to replace injured or dead neurons. The biological and cellular basis of neural injury is of special importance to neurosurgery, particularly as therapeutic options to treat a variety of CNS diseases becomes greater. (C) 2002 Published by Elsevier Science Ltd.