Nitric oxide in damage, disease and repair of the peripheral nervous system

Peripheral nerves provide essential connections between the central nervous system and muscles, autonomic structures and sensory organs. Nitric oxide (NO) participates in critical actions involving several aspects of peripheral nerve function and disease. It offers important roles in "normal" afferent signaling of pain through the dorsal horn of the spinal cord and in autonomic control through nitrergic innervation. NO is generated during the fundamental processes of Wallerian degeneration of peripheral nerves following injury that bear on subsequent regenerative events. Through its actions on vasa nervorum, the blood supply to nerves, NO participates in microvascular changes following injury but also has direct roles in axon and myelin breakdown and "clearance" prior to regeneration. During such processes, NO contributes to the development of neuropathic pain. Excessive local levels of NO during inflammation may damage axons and growth cones. Low-grade chronic rises in NO may also contribute toward peripheral nerve damage, or neuropathy in diabetes. In this review, we consider the evidence for these roles and their potential importance in disease and repair of peripheral nerves.

Penetrating grease gun injury in the face

We present the case of a sailor who sustained a penetrating grease gun injury to his face, and the challenging subsequent series of events.

Effects of sensitization of trigeminovascular neurons to triptan therapy during migraine

Migraine is a neurological disorder which leads to recurring, unilateral, throbbing headache, associated with variable incidence of aura (i.e., visual, sensory and motor function disturbances), nausea and vomiting, photophobia and phonophobia, fatigue, and enhanced irritability. We have recently shown that migraine headache is also associated with high incidence of ipsilateral cutaneous allodynia, particularly in periorbital and temporal skin areas. Patients who experience cutaneous allodynia during migraine feel that their skin hurts in response to otherwise innocuous activities such as combing, shaving, taking a shower, or wearing glasses or earrings. Here, we present evidence to support the view that the development of throbbing in the initial phase of migraine is mediated by sensitization of peripheral trigeminovascular neurons that innervate the meninges, and that the development and maintenance of cutaneous allodynia later in the attack is propelled by sensitization of central trigeminovascular neurons which receive converging sensory input from the meninges as well as from the scalp and facial skin. We also present evidence that the development of cutaneous allodynia during migraine is detrimental to termination of acute migraine attacks using triptans (5HT1B/1D receptor agonist).

Quantitation of thea prioridosimetric capabilities of spatial points in inverse planning and its significant implication in defining IMRT solution space

In inverse planning, the likelihood for the points in a target or sensitive structure to meet their dosimetric goals is generally heterogeneous and represents the a priori knowledge of the system once the patient and beam configuration are chosen. Because of this intrinsic heterogeneity, in some extreme cases, a region in a target may never meet the prescribed dose without seriously deteriorating the doses in other areas. Conversely, the prescription in a region may be easily met without violating the tolerance of any sensitive structure. In this work, we introduce the concept of dosimetric capability to quantify the a priori information and develop a strategy to integrate the data into the inverse planning process. An iterative algorithm is implemented to numerically compute the capability distribution on a case specific basis. A method of incorporating the capability data into inverse planning is developed by heuristically modulating the importance of the individual voxels according to the a priori capability distribution. The formalism is applied to a few specific examples to illustrate the technical details of the new inverse planning technique. Our study indicates that the dosimetric capability is a useful concept to better understand the complex inverse planning problem and an effective use of the information allows us to construct a clinically more meaningful objective function to improve IMRT dose optimization techniques.

Influence of Localized Excited States on the Transition Moment Directions of Charge Transfer Complex Absorptions

The influence of localized excited (LE) states on the spectroscopy of charge transfer (CT) complexes has been examined for a series of complexes formed between methyl-substituted benzene donors and 1,2,4,5-tetracyanobenzene as acceptor in 1,2-dichloroethane and octanenitrile solvents. A molecular orbital model was used to describe the appearance of multiple CT absorption bands that occur in the spectra of these complexes. The influence of LE states in these CT absorptions was explored using time-resolved linear dichroism spectroscopy where the direction of the CT transition moment vector (TMV) was used to probe the magnitude of intensity borrowing. The TMV directions for each of the observed CT transitions within the absorption spectra were determined for several complexes. In some cases, the observed CT transitions were interpreted as being pure CT transitions; in others the observed transitions are influenced significantly by a LE transition. The correlation between the TMV directions and the transition energy suggests that the magnitude of intensity borrowing is influenced not only by the energy difference between the CT and LE transitions but also by the specific character of the transitions under consideration.

DNA replication licensing and cell cycle kinetics of oligodendroglial tumours

The convergence point of growth-signalling pathways that control cell proliferation is the initiation of genome replication, the core of which is the assembly of pre-replicative complexes (pre-RCs), resulting in chromatin being ‘licensed’ for DNA replication in the subsequent S phase. The Mcm2–7 complex is a core constituent of the pre-RC, whose recruitment to replication origins is dependent on the Cdt1 loading factor. Geminin is a potent inhibitor of the initiation of DNA replication by preventing Mcm2–7 assembly at origins via its interaction with Cdt1, ensuring genomic integrity through suppression of re-initiation events in S phase. Here we investigate the regulation of Ki67, Mcm2, p21, caspase 3 and Geminin in a series of 55 oligodendrogliomas to provide an integrated picture of how cellular proliferation and programmed cell death are dysregulated in these tumours. Geminin does not behave as an inhibitor of cell proliferation, its labelling index rising with increasing growth fraction as defined by Ki67 or Mcm2 expression. Geminin is expressed in a higher proportion of cells in higher grade tumours (P<0.001) and shows a strong correlation to proliferation and replication licensing (P<0.01), but not apoptosis. Increasing tumour anaplasia is not associated with loss of Geminin. Importantly, the G1 phase of the proliferative cell cycle, as assessed by the Geminin/Ki67 ratio, shortens with increasing anaplasia, providing new potential algorithms for prognostic assessment. Origin licensing proteins thus provide powerful novel tools for assessment of tumour cell cycle kinetics in routinely processed surgical biopsy material.

The Nature of the Rapid Relaxation of Excited Charge-Transfer Complexes

Examples of contact radical-ion-pair (CRIP) formation from excited charge-transfer (CT) complexes are described. The reduced absorption and emission spectra of the CT complexes formed between hexamethylbenzene, pentamethylbenzene, and durene donors and 1,2,4,5-tetracyanobenzene (TCNB) in 1,2-dichloroethane (DCLE) exhibit a mirror image relationship, suggesting that each set of spectra describes transitions between the same two states. It was concluded that a CRIP is produced immediately upon excitation of the CT complex and that relaxation of the CRIP includes only minor geometry changes and changes in solvent polarization. In contrast to these results, the reduced absorption and emission spectra of the mesitylene (MES)/TCNB CT complex in DCLE are distinctly different and do not display a mirror image relationship. Time-resolved emission decay traces reveal the presence of an initial intermediate species that contributes approximately 10% of the total steady-state emission. The emission spectrum of this initial species mirrors the absorption spectrum of the MES/TCNB complex. In the MES/TCNB complex, excitation does not lead directly to the CRIP, and the relaxation of the excited complex must include an electronic component in addition to changes in geometry and solvation. The implications of these results on the applicability of golden-rule expressions of electron transfer are discussed.

Quantitative analysis of radiation-induced chromosome aberrations

We review chromosome aberration modeling and its applications, especially to biodosimetry and to characterizing chromosome geometry. Standard results on aberration formation pathways, randomness, dose-response, proximity effects, transmissibility, kinetics, and relations to other radiobiological endpoints are summarized. We also outline recent work on graph-theoretical descriptions of aberrations, Monte-Carlo computer simulations of aberration spectra, software for quantifying aberration complexity, and systematic links of apparently incomplete with complete or truly incomplete aberrations.

Did a severe flood in the Midwest cause an increase in the incidence of gastrointestinal symptoms?

Severe flooding occurred in the midwestern United States in 2001. Since November 2000, coincidentally, data on gastrointestinal symptoms had been collected for a drinking water intervention study in a community along the Mississippi River that was affected by the flood. After the flood had subsided, the authors asked these subjects (n = 1,110) about their contact with floodwater. The objectives of this investigation were to determine whether rates of gastrointestinal illness were elevated during the flood and whether contact with floodwater was associated with increased risk of gastrointestinal illness. An increase in the incidence of gastrointestinal symptoms during the flood was observed (incidence rate ratio = 1.29, 95% confidence interval: 1.06, 1.58), and this effect was pronounced among persons with potential sensitivity to infectious gastrointestinal illness. Tap water consumption was not related to gastrointestinal symptoms before, during, or after the flood. An association between gastrointestinal symptoms and contact with floodwater was also observed, and this effect was pronounced in children. This appears to be the first report of an increase in endemic gastrointestinal symptoms in a longitudinal cohort prospectively observed during a flood. These findings suggest that severe climatic events can result in an increase in the endemic incidence of gastrointestinal symptoms in the United States.

Neuro-oncology Practice in the UK

The aim of the study was to determine current U.K. neuro-oncology practice. A questionnaire was sent to all U.K. clinical oncologists who treat primary brain tumours. Results were distributed to these doctors with an invitation to attend a workshop in September 2000 to debate areas of differing practice and to review the existing related evidence. A further workshop was held in May 2002. The questionnaire responses and discussion of controversial areas, including the management of high-grade gliomas, low-grade gliomas, meningiomas, pituitary adenomas and multiple-brain metastases are included in this paper.

Frailty and the biochemical effects of recombinant human growth hormone in women after surgery for hip fracture

We report a randomised double blind controlled trial investigating the short-term biochemical and adverse clinical responses to recombinant human growth hormone (r-hGH) after surgery for hip fracture. Hip fractures are common, dangerous and expensive, typically affecting frail women with osteoporosis and reduced muscle mass and strength, factors also associated with poor clinical outcomes. Growth hormone therapy increases IGF-I levels, promotes anabolism and increases muscle strength in well older people and selected patient groups and therefore has therapeutic potential to assist recovery of frail patients.Thirty-one women, mean age 86 years, received 14 nightly subcutaneous injections of r-hGH 0.05 mg/kg/day (high dose) or 0.025 mg/kg/day (low dose), or placebo from the 4th post-operative day. There were several serious adverse clinical events but no excess number of adverse events in the r-hGH treatment groups. The r-hGH treatment groups had similar serum IGF-I and IGFBP-3 responses, both significantly different from placebo. The large inter-individual variation of IGF-I responses were inversely correlated with pre-treatment indicators of frailty (body composition and functional abilities).

Processing of global, but not local, motion direction is deficient in schizophrenia

Visual motion processing is compromised in a substantial proportion of schizophrenic patients, but precise neural mechanisms underlying the motion-processing deficit have not yet been elaborated. The visual motion pathway includes a local and a global processing stage, each of which has distinct neural substrates. Here, we attempt to identify the stage(s) that are implicated in impaired motion processing of schizophrenia-local, global, or both. For schizophrenia patients (n=23) and normal controls (n=26), we measured (1) the thresholds for detecting the motion direction of a random dot pattern, a task that requires global motion processing, and (2) the thresholds for detecting the motion direction of a grating, a task that requires only local motion processing, using psychophysical methods. Schizophrenia patients showed elevated thresholds for detecting the direction of coherent motion, particularly for the high dot-density target. In contrast, schizophrenia patients showed normal thresholds for detecting the direction of motion of a grating. The results indicate that the global, but not the local, processing stage of the visual motion system is compromised in schizophrenia patients, thus implicating motion-sensitive brain areas that possess large receptive fields for spatial and temporal integration, such as Middle Temporal Area/Medial Superior Temporal Area.

Alternative lengthening of telomeres and survival in patients with glioblastoma multiforme

Despite advances in the molecular pathogenesis of glioblastoma multiforme, no reliable prognostic markers have been identified. We analysed telomerase activity and telomere lengths in glioblastoma multiformes from 77 patients. 19 patients (25%) had tumours with the alternative-lengthening-of-telomere (ALT) phenotype. Median survival for patients with this phenotype was 542 days (95% CI 114-970) compared with 247 days (224-270) for glioblastoma multiformes with normal telomeres (p=0.0003). Cox's regression analysis showed that this association is independent of age. In patients with non-ALT tumours, telomerase activity did not affect survival (median 287 [199-375] vs 236 [230-242] days, p=0.275). We conclude that ALT is a prognostic indicator for patients with glioblastoma multiforme.

Commentary: eye movement research with clinical populations

The preceding set of chapters span the disciplines of neurology and psychiatry, and provide a diverse introduction to clinical eye movement research. They illustrate how oculomotor paradigms can be used to learn about acute and chronic perturbations in brain function, disturbances in brain development, disturbances in sensorimotor as well as cognitive systems, and the effects of therapeutic and illicit drugs on brain function. This commentary discusses these contributions, provides an overview of broad methodological issues involved in applying eye movement studies to psychiatric populations using the antisaccade task as an exemplar, and considers the potential of collaborations between eye movement and brain imaging researchers to advance understanding of clinical eye movement abnormalities and of what they reveal about the organization of the oculomotor system.

Identification of molecular markers associated with leptine in reciprocal backcross families of diploid potato

Solanum phureja clone 1-3 and S. chacoense clone 80-1 have a zero and high leptine content in their foliage, respectively. An F(1) hybrid (CP2) was intermediate for the trait, but self-incompatible. Two reciprocal backcross families, PBCp ( phu 1-3 x CP2) and PBCc (CP2 x phu 1-3), and a family of monoploids derived by anther culture of CP2, were characterized for leptine as the aglycon, acetylleptinidine (ALD), content in leaves by gas chromatography. ALD was present in 43 of 87 genotypes in the PBCp backcross, implying simple genetic control by a dominant gene. However, the ALD levels were low compared to CP2. In the PBCc backcross, only 7 of 42 genotypes expressed ALD at a level generally higher than in PBCp. This ratio was significantly different from the 1:1 segregation observed in the reciprocal backcross and suggests a cytoplasmic influence. ALD levels in the CP2 monoploids ranged from 0 to 8,968 &mgr;g.g(-1) of dry weight (dw) with 18 individuals expressing ALD and five with 0 ALD content. Ten high (mean ALD = 546 &mgr;g.g(-1) of dw) and ten low (mean ALD = 0) individual plants within PBCp and seven high (mean ALD = 3,037 &mgr;g.g(-1) of dw) and eight low (mean ALD = 0) individual plants within PBCc were used for bulk segregant analysis (BSA) using 214 RAPD (randomly amplified polymorphic DNA) primers. Three RAPD primers (OPQ-2, OPT-16 and OPT-20) amplified bands exclusively in bulks containing DNA mixes of high ALD producers in both PBCp and PBCc populations. These results suggest that these markers were associated in coupling to ALD content. ANOVAs for ALD content verified association between the markers and the trait. A CAPS (cleaved amplified polymorphic sequence) marker, GP82A, was also significantly associated with ALD production in both the monoploid and the PBCp populations. None of the RAPD markers was associated to ALD in the monoploids but one was associated in repulsion. The monoploid data indicate the likelihood of a recessive gene(s) that controls leptine production, but the backcross data indicate the action of modifying loci.