bluuebunny/crossref_metadata_2025 huggingface dataset:
Establishment of Perennial Shrub and Tree Species in Degraded Eucalyptus salmonophloia (Salmon Gum) Remnant Woodlands: Effects of Restoration Treatments
Authors: Yates C. J. , Hobbs R. J. , Atkins L.
Published: March 2003

Woodlands dominated by Eucalyptus salmonophloia (salmon gum) occur throughout the fragmented landscape of the southwestern Australian wheatbelt. These remnants are often degraded by livestock grazing and weed invasion and in many cases there is little or no understorey remaining and little or no regeneration of the dominant tree E. salmonophloia. There is a growing interest in developing techniques for restoring remnant woodlands. This study describes techniques for establishing seedlings of the dominant tree and perennial understorey species in E. salmonophloia (salmon gum) woodlands degraded by livestock grazing. The study tests the hypothesis that, in addition to the exclusion of livestock, management of weeds and reintroduction of plant species, restoration of plant species diversity will require techniques which mimic large‐scale disturbances, reduce soil compaction, and restore soil water infiltration to suitable rates. Five‐month‐old seedlings of the dominant tree E. salmonophloia and four commonly associated woody shrubs (Acacia hemiteles, Atriplex semibaccata, Maireana brevifolia, and Melaleuca pauperiflora) were planted into areas that differed with respect to grazing (–rabbit/ −livestock and +rabbit/–livestock), tree canopy disturbance (+/–competition with tree canopy) and amelioration of soil compaction (+/–deep ripping). Following three growing seasons and two summers, the exclusion of rabbits had no significant effect on the survival and growth of planted species. As a consequence grazing treatments are pooled for the purposes of presenting the impacts of removing competition with adult trees and soil deep ripping. The removal of competition with adult E. salmonophloia trees significantly improved the survival of E. salmonophloia seedlings but did not improve survival of understorey species. Deep ripping the soil significantly improved the survival of both E. salmonophloia and the shrub A. hemiteles but did not improve the survival of other understorey species. In contrast to seedling survival, the removal of adult E. salmonophloia trees and deep ripping soil significantly increased the growth of all species. The results indicate that increasing levels of intervention will increase the chances of successfully restoring tree and understorey species diversity in degraded E. salmonophloia woodlands.
Does Coastal Foredune Stabilization with Ammophila arenaria Restore Plant and Arthropod Communities in Southeastern Australia?
Authors: Webb Cameron E. , Oliver Ian , Pik Anthony J.
Published: March 2003

In this study we examine whether stabilization of denuded coastal foredunes in southeastern Australia with the exotic grass species Ammophila arenaria (marram grass) restores plant and ground‐active arthropod assemblages characteristic of undisturbed foredunes. Vascular plants and arthropods were sampled from foredunes that had been stabilized with marram grass in 1982, and from foredunes with no obvious anthropogenic disturbance (control dunes). All arthropods collected were sorted to Order, and ants (81.5% of all specimens) were further sorted to morphospecies. Abundance within arthropod Orders, as well as richness, composition, and structure of the plant and ant assemblages from control and stabilized dunes, were compared. The abundance of Diptera was significantly greater on stabilized dunes, while the abundance of Isopoda was significantly greater on control dunes. There were no significant differences in morphospecies richness or composition of ant assemblages on the two dunes types, although some differences in the abundances of individual morphospecies were observed. By contrast, stabilized dunes exhibited lower plant species richness and highly significant differences in plant species composition, due mainly to the large projected foliage cover of marram grass. The study revealed that after 12 years, the vegetation composition and structure of stabilized dunes was still dominated by marram grass and, as a result, invertebrate assemblages had not been restored to those characteristic of undisturbed foredunes.
Rosette Recruitment of a Rare Endemic Forb (Gaura neomexicanaSubsp.coloradensis) with Canopy Removal of Associated Species
Authors: Munk Linda M. , Hild Ann L. , Whitson Thomas D.
Published: March 2003

Gaura neomexicanasubsp.coloradensisMunz (Onagraceae), (Colorado butterfly plant), a short‐lived perennial forb, became listed as a threatened species by the U.S. Fish and Wildlife Service in October 2000 because of its small global range and population size. This endemic subspecies consists of only 18 extant populations within southeastern Wyoming, southwestern Nebraska, and northeastern Colorado. Wyoming occurrences are on private land with the exception of three occurrences on F. E. Warren Air Force Base, near Cheyenne.Gaura neomexicanasubsp.coloradensismay be displaced by many competitors, includingCirsium arvense(L.) Scop. (Canada thistle), an invasive, noxious weed. In June 1998, threeG. neomexicanasubsp.coloradensispopulations were examined for rosette establishment in the presence of and after removal of associated species. The four study treatments removed: (1)Cirsium arvense, (2) grass and forb canopy and associated litter, (3) grass and forb canopy, litter, andC. arvense, and (4) no removal of associated plant species (control). MatureG. neomexicanasubsp.coloradensisplants were evaluated for height, number of leaves, and capsule production. The mature plant characteristics monitored in 1998 were not good indicators of subsequentG. neomexicanasubsp.coloradensisrosette densities in the following spring. Recruitment was assessed by counting new rosettes in the fall 1999. Although bothG. neomexicanasubsp.coloradensisand the exoticC. arvensehave comparable habitat, removal ofC. arvensedid not increaseG. neomexicanasubsp. coloradensis vegetative growth, seed capsule production, or rosette density. Removal of other forbs, grass, and litter, however, increasedG. neomexicanasubsp.coloradensisrosette density in the following two years, indicating that canopy removal of associated species can enhance rosette establishment of this rare native. The accumulation of dense vegetative cover and litter associated with the absence of herbivory and fire may contribute to the decline of rare species in rich riparian habitats. Return of herbivory and fire in mesic sites to reduce standing biomass accumulations should be considered in restoring recruitment potential to rare monocarpic species.
Atrophy Of Foot Muscles In Type 1 Diabetic Patients In Relation To Presence And Severity Of Neuropathy
Authors: Andersen H , Gjerstad Md , Jakobsen J.
Published: March 2003

Diabetic patients with neuropathy may develop motor dysfunction. In a previous study we found atrophy of the ankle extensors and flexors in neuropathic patients being more pronounced distally. This indicates that evaluation of the morphology of the foot muscles may be more sensitive for the detection of muscular atrophy in neuropathic patients. In this study we included 23 type 1 diabetic patients with a diabetes duration of 29 years (16–38) (median, range). For comparison, 23 age‐, sex‐, weight‐, and height‐matched control subjects were included. Using magnetic resonance imaging, the muscular morphology of the non‐dominant foot was evaluated in all subjects. Applying stereological techniques on consecutive cross‐sectional magnetic resonance images, the total volume of the foot muscles was determined. In addition, the diabetic patients were assessed clinically with a neuropathy symptom score and a neurological impairment score. Patients were also evaluated with motor nerve conduction studies and quantitative sensory examination. As compared with the healthy controls, the volume of the foot muscles was reduced in the diabetic patients being 117 cm3 (23–209) (median, range) and 166 cm3 (94‐263) (p < 0.005), respectively. In the 8 non‐neuropathic patients, the muscle volume was 106% (70–130) of the matched controls, whereas the 15 neuropathic patients had a muscle volume of only 49% (11–95) of the controls (p < 0.001). Furthermore, there was a close inverse relationship between the neurological impairment score and the total muscle volume (r = −0.81, p < 1*10−5). In conclusion, the volume of the foot muscles is reduced in long‐term type 1 diabetic patients with neuropathy. The muscular atrophy is closely related to the severity of neuropathy. We suggest assessment of the volume of the foot muscles to be a sensitive method for the detection of motor dysfunction in diabetic neuropathy.
Painful Diabetic Neuropathy ‐ A Therapeutic Challenge For The New Millennium
Authors: Boulton Ajm
Published: March 2003

Although less than 20% of patients with diabetic neuropathy experience severe symptoms, the management of painful diabetic neuropathy presents a major therapeutic challenge. Pain may occur as a feature not only of chronic or acute sensory neuropathy, but also the focal neuropathies, however, this lecture will focus on pain in symmetrical distal polyneuropathy. A number of theories exist to explain the mechanisms of pain in diabetic neuropathy: these include ectopic impulse formation by regenerating sprouting axons, various neuro structural theories and, more recently, ischaemia of peripheral nerve due to active epineurial arterio venous shunting. A number of scoring systems exist to assess neuropathic pain: which ever is used, it must rely upon the patient's description of the painful symptoms they are experiencing. A therapeutic approach to neuropathic pain should firstly exclude non‐diabetic causes of neuropathy, and then aim to obtain optimal stable glycaemic control. A number of therapeutic agents exist that have been shown in controlled trials to alleviate painful neuropathic symptoms; these include the tricyclic drugs, newer anti convulsant agents such as Gabapentin and Topiramate, and also the centrally‐acting drug Tramadol. Some evidence exists for the efficacy of the topical agent Capsaicin. Other promising new agents include alpha lipoic acid. A number of therapies may well be helpful although unproven in controlled trials, and these include acupuncture and electrical spinal cord stimulation.
Possible Role Of Uncoupling Proteins As Protectors From Hyperglycemia‐Induced Neuropathy
Authors: Gustafsson H , Söderdahl T , Forsby A.
Published: March 2003

Diabetic neuropathy may be induced by oxidative stress, possibly as a consequence of the hyperglycemic situation. Uncoupling proteins (UCPs) have been reported to function as anti‐oxidants by decreasing the production of reactive oxygen species (ROS). These mitochondrial carrier proteins are located in the inner membrane of mitochondria and upon activation, they dissipate proton gradients, which generates heat instead of ATP. In humans, UCP2 and UCP3 are believed to play a role as energy dissipaters and aberrant function could underlie metabolic defects seen in both obesity and non‐insulin dependent diabetes (NIDDM). In this study we have shown that human neuroblastoma SH‐SY5Y cells expressed UCP2 and UCP3 natively and that the expression was upregulated by insulin and IGF‐I via the IGF‐I receptor. In highly differentiated SH‐SY5Y cells, which were cultured in hyperglycemic N2‐medium (30 mM and 60 mM glucose) containing 8.6 nM insulin, the number of neurites per cell and total cellular protein levels/dish were significantly decreased, as compared to cells grown in N2‐medium containing 17 mM glucose. This effect was abolished when the cells were grown with 10 nM IGF‐I at 30 mM glucose and decreased at 60 mM glucose. Furthermore, in hyperglycemic cells, the IGF‐I‐induced increase in UCP3 protein levels was inhibited. Non‐differentiated cells responded to hyperglycemic situations by increased rate of proliferation, leaving cell morphology intact. We conclude that differentiated SH‐SY5Y cells can serve as an in vitro model for hyperglycemic neurons and that IGF‐I protects the cells from hyperglycemia‐induced neuropathy, suggestively by the involvement of UCP3.
Immunopathogenetic Role Of The M‐Protein In Neuropathy Associated With IgA Monoclonal Gammopathy
Authors: Casellato C , Allaria S , Scarlato G , Nobile‐Orazio E.
Published: March 2003

Neuropathy has been reported in some patients with IgA monoclonal gammopathy of undetermined significance (MGUS) but the clinical and pathogenetic relevance of this association remains unclear. This is because the clinical and electrophysiological features of the neuropathy in reported patients were quite heterogeneous and only occasionally endoneurial deposits or anti‐neural reactivity of IgA M‐proteins were found. In order to clarify the possible role of IgA M‐proteins in the neuropathy we studied their reactivity with nerve antigens in 12 patients with neuropathy associated with IgA MGUS and in 15 patients with IgA MGUS without clinical or electrophysiological evidence of neuropathy. Patients' sera were tested for IgA reactivity with the glycolipids GM1, GM2, GD1a, GD1b, GQ1b and sulfatides by ELISA and with central (CNS) and peripheral nervous system (PNS) myelin and whole nerve homogenates by Western Blot. No IgA reactivity with any of the gangliosides tested or sulfatide was detected by ELISA in patients with neuropathy and IgA MGUS. By Western blot only one neuropathy patient had an intense IgA reactivity with several protein bands of the molecular weight (MW) of 80 to 200 kD, including high MW neurofilaments. A similar though less intense IgA reactivity with the same bands was detected in one patient without neuropathy. No other reactivity with neural proteins was detected in patients' sera more frequently or more intensely than in controls. The clinical features of the neuropathy in the four patients whose clinical reports were available showed an usually mild, predominantly motor (2) or sensory (1) or mixed (1) impairment, while electrophysiological studies showed a predominant axonal (2), demyelinating (1) or mixed (1) neuropathy. In the only patient in whom sural nerve biopsy was performed no endoneurial deposits of IgA were found. The heterogeneity of the clinical and electrophysiological findings in these patients together with the lack of a consistent pattern of IgA reactivity with neural antigens in the 12 patients examined fail to support, at least in these patients, a possible immunopathogenetic role of the IgA M‐proteins in the neuropathy.
The Opioid Receptor‐4 (OP4) Is Involved In The Spinal Plasticity During The Development Of Neuropathic Pain In The Rat
Authors: Corradini L , Briscini L , Ongini E , Bertorelli R.
Published: March 2003

Nociceptin (N/OFQ), possibly acting through its receptor (OP4), shows anti‐nociceptive properties when administered in the spinal cord of neuropathic rats (Yamamoto et al., 1998; Hao et al., 1999). OP4 has also been described as a mediator of spinal facilitation occurring in the chronic constriction injury (CCI) rat model (Yamamoto et al., 2000). Thus, we studied the spinal effect of N/OFQ in this model and the molecular changes that occurred in both lumbar enlargement and dorsal root ganglia (DRG) of neuropathic rats. The sciatic nerve of rodents was unilaterally ligated following the Bennett & Xie (1988) procedure and their mechanical pain threshold was recorded by von Frey hairs. Rats responding to non‐noxious stimuli (<3.6 g) displayed allodynic‐like behaviour and were selected for pharmacological studies. N/OFQ (0.2–20 nmol) injected intrathecally (i.t.) in rats induced a dose‐dependent anti‐allodynic activity. Five min post drug administration, a rise in the pain threshold was observed with 2 nmol [(23.9 g (18.3–31.5) vs 2.9 g (1.9–4.4) of the control group; p < 0.01]. This effect was OP4‐mediated as the receptor antagonist, [Nphe1]N/OFQ(1–13)NH2 (60–120 nmol; Guerrini et al., 2000), prevented the activity of N/OFQ [9.8 g (4.3–22.1) and 6.17 g (2.2–17.3) vs 34.7 g (14.5–82.7) in the N/OFQ treated group, 5 min post injection; p < 0.05 and p < 0.01, respectively]. The two described OP4 splice variants (Xie et al., 1999) were up‐regulated in the ipsilateral spinal tissues of allodynic rats. The short form increased by 100% while the long form increased by 50%vs control values in the spinal cord. In the DRG, both isoforms of OP4 were increased by 60 and 50%, respectively. This up‐regulation is time‐dependent and it is closely related to the allodynic‐like behaviour. On the contrary, the mRNA expression of either the OP4 receptor or the preproN/OFQ was not modified in either side of the lumbar spinal cord or DRG. Moreover, OP4 knockout mice showed a marked decrease in thermal pain threshold after CCI as measured by the plantar test. These results demonstrate a modulation of OP4 expression in the development of mechano‐allodynia in the CCI rat model. Further studies are necessary to clarify the function of OP4 receptor reorganization in the spinal plasticity occurring in persistent pain.
Neurophysiological Studies In Metachromatic Leukodistrophy
Authors: Galardi G , Amadio S , Maderna L , Medaglini S , Wrabetz L , Comi G.
Published: March 2003

Metachromatic Leukodystrophy (MLD) is a lysosomal storage disease caused by deficiency of Arylsulfatase A (ASA) with accumulation of cerebroside sulfate in the white matter of central and peripheral nervous system. Late infantile, juvenile and adult forms have been described according to the age of onset and severity. Several studies demonstrated the diagnostic usefulness of neurophysiological tests in leukodystrophies, but their role in the progression of the disease and/or on the therapeutic monitoring is still to be established. Four patients with late juvenile MLD were studied by means of visual, auditory, somatosensory and motor evoked potentials to monitor central nervous system involvement and by means of motor and sensory conduction velocity to monitor peripheral nerve function. All neurophysiological tests demonstrated their ability in detecting abnormalities of the related neurological system. Abnormal findings of multimodal Evoked Potentials and sensory nerve conduction study consisted of disappearance of responses while motor nerve conduction study showed quantitative data which consisted of slowing of conduction velocity. As motor nerve fibers are relatively spared in MLD patients, motor nerve conduction studies would provide a simple method for evaluating the course of the disease and therapeutical efficacy. Unfortunately no neurophysiological tests are presently available for long‐term follow‐up of CNS damage in MLD.
Involvement of IGF‐1 and IGFBP‐1 and ‐3 in Axon‐Schwann Cell Interactions
Authors: Nobbio L , Garrone S , Barreca A , Grandis M , Mancardi GL , Minuto F , Schenone A.
Published: March 2003

Insulin‐like growth factor‐I (IGF‐I) promotes proliferation, differentiation and survival of Schwann cells (SC). Moreover, an effect of IGF‐I on axon regeneration has been proposed. However, although IGF‐I expression has been shown in postnatal SC and in SC precursors thus suggesting an autocrine regulation of SC survival, release of the trophic factor by SC has not been clearly demonstrated. To investigate the role of the IGF system, we studied the supernatant of primary SC cultures, purified sensory neuron cultures, and co‐cultures of SC and sensory neurons. Moreover, since in its free form IGF‐I interacts with specific binding proteins (IGFBPs) whose active role in modulating the effects of IGF‐I is increasingly recognized, in the same culture systems we also evaluated levels of IGFBP‐1 and ‐3. We established SC, sensory neuron and SC/sensory neuron cultures according to classical procedures. Purified SC (87,500 cells/dish) were grown in presence of serum, forskolin, cholera toxin and bovine pituitary extract. Purified sensory neurons were grown in the presence of serum and NGF; part of it was maintained alone and the rest was added with SC (87,500 cells/dish) and grown in a co‐culture system. After 1 month all cultures were washed with PBS and grown for at least 4 days in a serum‐free medium before collecting their conditioned media (CM) for chromatography assays. Similar IGF‐I levels were found into the CM of SC and of sensory neurons when grown as purified cultures (94.40 vs 73.80 ng/5×106 cell). Instead, higher amounts of IGF‐I were detected into the medium of SC/sensory neurons co‐cultures (277.70 ng/5×106 cell). IGFBP‐1 and ‐3 production was also found in both SC and sensory neuron purified cultures, but their expression was clearly higher in neurons compared to SC (0.74 vs 0.28 ng/5×106 cell for IGFBP‐1 and 4.48 vs 1.77 ng/5×106 cell for IGFBP‐3). Furthermore, SC/sensory neuron co‐cultures maintained high levels of IGFBP‐3 (3.93 ng/5×106) but not of IGFBP‐1 (0.28 ng/5×106). In conclusion, IGF‐1 is produced by both SC and pure sensory neurons, but co‐culturing the two cell populations results in a possible reciprocal stimulation to synthesize this growth factor. Moreover, the decrease of IGFBP‐1 in the medium of co‐cultures could be due to the production of IGFBP proteases by SC. This action could be a mechanism to increase IGF‐1 availability to the specific receptor.
Evaluation Of Alpha 1‐Adrenoceptor Antagonist On Diabetes‐Induced Changes In Peripheral Nerve Function, Metabolism, And Antioxidative Defense
Authors: Obrosova IG , Van Huysen C , Fathallah L , Cao XH , Stevens MJ , Greene DA
Published: March 2003

The role for nerve blood flow (NBF) vs. other factors in motor nerve conduction (MNC) slowing in short‐term diabetes was assessed by evaluating alpha(1)‐adrenoceptor antagonist prazosin on NBF, MNC, as well as metabolic imbalances and oxidative stress in the neural tissue. Control and diabetic rats were treated with or without prazosin (5 mg.kg (−1).d(−1) for 3 wk). NBF was measured by hydrogen clearance. Both endoneurial vascular conductance and MNC velocity were decreased in diabetic rats vs. controls, and this decrease was prevented by prazosin. Free NAD(+):NADH ratios in mitochondrial cristae, matrix, and cytosol assessed by metabolite indicator method, as well as phosphocreatine levels and phosphocreatine/creatine ratios, were decreased in diabetic rats, and this reduction was ameliorated by prazosin. Neither diabetes‐induced accumulation of two major glycation agents, glucose and fructose, as well as sorbitol and total malondialdehyde plus 4‐hydroxyalkenals nor depletion of myo‐inositol, GSH, and taurine or decrease in (Na/K)‐ATP‐ase activity were affected by prazosin. In conclusion, decreased NBF, but not metabolic imbalances or oxidative stress in the neural tissue, is a key mechanism of MNC slowing in short‐term diabetes. Further experiments are needed to estimate whether preservation of NBF is sufficient for prevention of nerve dysfunction and morphological abnormalities in long‐standing diabetes or whether the aforementioned metabolic imbalances closely associated with impaired neurotropism are of greater importance in advanced than in early diabetic neuropathy.
Intracellular Transport, Assembly, And Degradation Of Wild‐Type And Disease‐Linked Mutant Gap Junction Proteins
Authors: Vanslyke JK , Deschenes SM , Musil LS
Published: March 2003

More than 130 different mutations in the gap junction integral plasma membrane protein connexin32 (Cx32) have been linked to the human peripheral neuropathy X‐linked Charcot‐Marie‐Tooth disease (CMTX). How these various mutants are processed by the cell and the mechanism(s) by which they cause CMTX are unknown. To address these issues, we have studied the intracellular transport, assembly, and degradation of three CMTX‐linked Cx32 mutants stably expressed in PC12 cells. Each mutant had a distinct fate: E208K Cx32 appeared to be retained in the endoplasmic reticulum (ER), whereas both the E186K and R142W mutants were transported to perinuclear compartments from which they trafficked either to lysosomes (R142W Cx32) or back to the ER (E186K Cx32). Despite these differences, each mutant was soluble in nonionic detergent but unable to assemble into homomeric connexons. Degradation of both mutant and wild‐type connexins was rapid (t(1/2) < 3 h) and took place at least in part in the ER by a process sensitive to proteasome inhibitors. The mutants studied are therefore unlikely to cause disease by accumulating in degradation‐resistant aggregates but instead are efficiently cleared from the cell by quality control processes that prevent abnormal connexin molecules from traversing the secretory pathway.
Evaluation of three screening tests and a risk assessment model for diagnosing peripheral neuropathy in the diabetes clinic
Authors: Olaleye D , Perkins BA , Bril V
Published: March 2003

OBJECTIVE: With the aim of evaluating predictive power, three simple screening tests as alternates to nerve conduction tests for diagnosing diabetic peripheral neuropathy (DPN) were investigated. Results of the screening tests, along with the subjects' demographic and clinical characteristics, were planned as the variables for the development of a risk assessment tool for predicting DPN. DESIGN: This is a cross‐sectional multi‐group comparison study. The study utilized a predictive model derived from one subset of the study population, and prospectively tested in the other subset to predict the presence of neuropathy. SETTING: Diabetic Neuropathy Research Clinic of the Toronto General Hospital and University Health Network in Toronto, Ontario, Canada from June 1998 to August 1999. Sample population: data come from 478 subjects consisting of non‐diabetic reference subjects, and patients with type I and type 2 diabetes mellitus. OUTCOME MEASURES: Nerve conduction studies (NCS) comprised the primary defined outcome. The three screening sensory tests examined in the study were the Semmes‐Weinstein 10 g monofilament examination (SWME), superficial pain sensation, and vibration by the on‐off method. RESULTS: The three screening tests are significantly and positively correlated with NCS. An increase in the number of insensate responses in the screening test is associated with an increase in the abnormal NCS score. The strength of the association between NCS and each sensory test was greater when the neuropathy severity stage of the subject was added to the model. Both the SWME and vibration by the on‐off method tests demonstrated sufficient statistical power to differentiate non‐diabetic control subjects from subjects with diabetes, as well as to differentiate subjects with diabetes with and without neuropathy. These two tests, when compared with NCS, also demonstrated acceptable diagnostic performance characteristics in terms of high sensitivity and specificity, total number of correctly predicted cases, and receiver‐operating characteristic curves. CONCLUSION: This data, through the development of a model involving training and validation sets, demonstrates that the knowledge of clinical risk factors alters the interpretation of sensory tests for DPN. This finding lends further support to the validity of simple sensory testing maneuvers in the conditional diagnosis of DPN. We recommend annual screening with either the SWME or vibration by the on‐off method in the primary care and diabetes clinics.
Mutation analysis of 12 candidate genes for distal hereditary motor neuropathy type II (distal HMN II) linked to 12q24.3
Authors: Irobi Joy , Nelis Eva , Verhoeven Kristien , De Vriendt Els , Dierick Ines , De Jonghe Peter , Van Broeckhoven Christine , Timmerman Vincent
Published: March 2003

Abstract  Distal hereditary motor neuropathies (distal HMNs) are characterized by degeneration of anterior horn cells of the spinal cord resulting in muscle weakness and atrophy. Distal HMN type II is genetically linked to chromosome 12q24.3 and located within a 13 cM region flanked by D12S86 and D12S340. We previously excluded 5 positional and functional candidate genes for distal HMN II. Here, we report the exclusion of 12 additional candidate genes localized within the distal HMN II region; the genes include musashi (Drosophila) homolog 1 (MSI1), protein inhibitor of neuronal nitric oxide synthase (PIN), peripherin (PRPH), tubulin alpha ubiquitous (K‐ALPHA‐1), tubulin alpha 3 (TUBA3), tubulin alpha 6 (TUBA6), splicing factor arginine/serine‐rich 9 (SFRS9), U5 snRNP 100 kd (U5‐100K), putative chemokine receptor, GTP‐binding protein (HM74), MondoA, cut (Drosophila)‐like homeobox 2 (CUX2) and ADP‐ribosylation factor 3 (ARF3).
Orally‐Effective, Long‐Acting Sorbitol Dehydrogenase Inhibitors: Synthesis, Structure‐Activity Relationships, And In Vivo Evaluations Of Novel Heterocycle‐Substituted Piperazino‐Pyrimidines
Authors: Chu‐Moyer MY , Ballinger WE , Beebe DA , Berger R , Coutcher JB , Day WW , Li JC , Mylari BL , Oates PJ , Weekly RM.
Published: March 2003

Optimization of a previously disclosed sorbitol dehydrogenase inhibitor (SDI, II) for potency and duration of action was achieved by replacing the metabolically labile N,N‐dimethylsulfamoyl group with a variety of heterocycles. Specifically, this effort led to a series of novel, in vitro potent SDIs with longer serum half‐lives and acceptable in vivo activity in acutely diabetic rats (e.g., 62, 67, and 69). However, the desired in vivo potency in chronically diabetic rats, ED90 less than or equal to 5 mg/kg/day, was achieved only through further modification of the piperazine linker. Several members of this family, including 86, showed better than the targeted potency with ED90 values of 1‐2 mg/kg/day. Compound 86 was further profiled and found to be a selective inhibitor of sorbitol dehydrogenase, with excellent pharmacodynamic/pharmacokinetic properties, demonstrating normalization of sciatic nerve fructose in a chronically diabetic rat model for approximately 17 h, when administered orally at a single dose of 2 mg/kg/day.
Distinct Pattern Of Age‐Specific Incidence Of Guillain‐Barre Syndrome In Harbin, China
Authors: Cheng Q , Wang DS , Jiang GX , Han H , Zhang Y , Wang WZ , Fredrikson S.
Published: March 2003

We describe the age‐ and sex‐specific incidence of Guillain‐Barré syndrome (GBS) in Harbin, China, based on the information from a prospective survey among a well‐defined large population during one year. A network of physicians reported incident patients with a GBS diagnosis from a general population of 5.4 million inhabitants in Harbin, China, during the period from 1 October 1997 to 30 September 1998. Each reported patient was examined by senior neurologists and the GBS diagnosis was validated according to standard diagnostic criteria. All GBS patients were followed‐up for six months after onset. Admission registers at all hospitals in Harbin were also checked afterwards for screening patients with a GBS diagnosis who might have been missed. During the study period, 79 patients with a GBS diagnosis were reported. After validation, the GBS diagnosis was confirmed in 70 patients. Another GBS patient was found through the screening of admission registers at hospitals. Among them, 36 GBS patients were residents in Harbin and the other 35 patients were from geographical areas out of Harbin. The GBS incidence, age‐adjusted to the European standard population, was 0.66 (95% CI 0.46‐0.91) per 100,000 person‐years, with a male to female ratio of 1.4. The highest GBS incidence was found in the youngest age‐group and the incidence among the elderly was remarkably lower than those reported from other populations in Western countries. Possible explanations for the distinct pattern of age‐specific incidence of GBS are discussed. Further studies are needed.
Voltage Opens Unopposed Gap Junction Hemichannels Formed By A Connexin 32 Mutant Associated With X‐Linked Charcot‐Marie‐Tooth Disease
Authors: Abrams CK , Bennett MVL , Verselis VK , Bargiello TA.
Published: March 2003

The X‐linked form of Charcot‐Marie‐Tooth disease (CMTX) is an inherited peripheral neuropathy that arises in patients with mutations in the gene encoding the gap junction protein connexin 32 (Cx32), which is expressed by Schwann cells. We recently showed that Cx32 containing the CMTX‐associated mutation, Ser‐85‐Cys (S85C), forms functional cell‐cell channels in paired Xenopus oocytes. Here, we describe that this mutant connexin also shows increased opening of hemichannels in nonjunctional surface membrane. Open hemichannels may damage the cells through loss of ionic gradients and small metabolites and increased influx of Ca2+, and provide a mechanism by which this and other mutant forms of Cx32 may damage cells in which they are expressed. Evidence for open hemichannels includes: (i) oocytes expressing the Cx32(S35C) mutant show greatly increased conductance at inside positive potentials, significantly larger than in oocytes expressing wild‐type Cx32 (Cx32WT); and (ii) the induced currents are similar to those previously described for several other connexin hemichannels, and exhibit slowly developing increases with increasing levels of positivity and reversible reduction when intracellular pH is decreased or extracellular Ca2+ concentration is increased. Although increased currents are seen, oocytes expressing Cx32(S35C) have lower levels of the protein in the surface and in total homogenates than do oocytes expressing Cx32WT; thus, under the conditions examined here, hemichannels in the surface membrane formed of the Cx32(S85C) mutant have a higher open probability than hemichannels formed of Cx32WT. This increase in functional hemichannels may damage Schwann cells and ultimately lead to loss of function in peripheral nerves of patients harboring this mutation.
HERPES SIMPLEX‐MEDIATED GENE TRANSFER OF NERVE GROWTH FACTOR PROTECTS AGAINST PERIPHERAL NEUROPATHY IN STREPTOZOTOCIN‐INDUCED DIABETES IN THE MOUSE
Authors: Goss JR , Goins WF , Lacomis D , Mata M , Glorioso JC , Fink DJ
Published: March 2003

Peripheral neuropathy is a common and debilitating complication of diabetes. In animal models, neurotrophic factors can prevent progression of the neuropathy, but adverse effects prevent systemic administration in adequate doses to treat human disease. We examined whether gene transfer with replication‐defective genomic herpes simplex virus (HSV) vectors modified to express nerve growth factor (NGF) could be used to prevent progression of neuropathy in mice. Diabetes induced by streptozotocin (STZ) resulted in a sensory neuropathy manifest by a decrease in the foot sensory nerve amplitude (FSA; control = 20 +/− 0.1 muV, treated = 14 +/− 0.1 muV). Transduction of dorsal root ganglia in vivo with an HSV‐based vector expressing NGF under the control of the human cytomegalovirus immediate early promoter (vector SHN) or the HSV latency active promoter 2 (vector SLN) by footpad inoculation 2 weeks after STZ administration protected against the decrease in FSA (22 +/− 1.4 muV and 21 +/− 1.7 muV, respectively) measured 4 weeks later. Injection of SHN into inguinal adipose tissue 2 weeks after onset of diabetes also prevented the decrease in FSA (20 +/− 3.3 muV). These results suggest that gene transfer with an NGF‐producing herpes‐based vector may prove useful in the treatment of diabetic neuropathy.
A MOUSE MODEL FOR PERIPHERAL NEUROPATHY PRODUCED BY A PARTIAL INJURY OF THE NERVE SUPPLYING THE TAIL
Authors: Back SK , Sung B , Hong SK , Na HS
Published: March 2003

We attempted to develop a mouse model for peripheral neuropathy by a partial injury of the nerve supplying the tail. Under enflurane anesthesia, the unilateral superior caudal trunk was resected between the S3 and S4 spinal nerves. Tests for thermal allodynia were conducted by immersing the tail into 4 or 38°C water. The mechanical allodynia was assessed by stimulating the tail with a von Frey hair (1.96 mN, 0.2 g). After the nerve injury, the experimental animals had shorter tail withdrawal latencies to cold and warm water immersion than the presurgical latency, and exhibited an increase in tail response to von Frey stimulation. We interpret these abnormal sensitivities as the signs of mechanical, cold and warm allodynia following the superior caudal trunk injury in the mouse.
GROWTH AND PHOTOSYNTHESIS OF MARINE SYNECHOCOCCUS (CYANOPHYCEAE) UNDER IRON STRESS
Authors: Henley William J. , Yin Yi
Published: March 2003

Prokaryotic picoplankton such as Synechococcus are relatively abundant in putatively Fe‐limited high‐nutrient, low‐chlorophyll (HNLC) regions of the oceans. The physiology of Synechococcus under Fe stress has been studied less than eukaryotic algae. Recent evidence suggests that although biomass and growth rates of Synechococcus are not typically Fe limited in situ, cells may still exhibit symptoms of Fe stress. We grew Synechococcus A2169 and WH7803 in laboratory batch cultures in the artificial medium Aquil and enriched natural seawater, at a series of Fe concentrations and Fe:macronutrient ratios, and with either nitrate or ammonium as the sole nitrogen source. Cell yields, and in some experiments exponential specific growth rate (μ), were more readily Fe limited in the Atlantic isolate WH7803 than in the equatorial Pacific isolate A2169. In both strains, final cell yields spanned about an order of magnitude and decreased continuously with Fe concentration from 900 to 3.6 nM (150 μM N, 10 μM P), whereas μ decreased much less and only at Fe concentrations below 90 nM. Synechococcus yield was controlled by both absolute Fe concentration and Fe:macronutrient ratio, but μ was determined primarily by absolute Fe concentration. Contrary to theoretical predictions, neither yield nor μ was higher in Fe‐limited cells grown in ammonium compared to nitrate. Under severe Fe stress, cellular chlorophyll (Chl) content and light‐saturated gross photosynthetic capacity (Pcellm) decreased proportionately, and dark respiration (Rcelld) increased, such that net Pcellm was extremely low but gross PChlm was unchanged. This is the first report of an absolute increase in Rcelld under Fe stress in phytoplankton.
MEASURING RATES OF AMMONIUM ASSIMILATION IN MARINE ALGAE: USE OF THE PROTONOPHORE CARBONYL CYANIDE m‐CHLOROPHENYLHYDRAZONE TO DISTINGUISH BETWEEN UPTAKE AND ASSIMILATION
Authors: Rees T. Alwyn V. , Grant Coral M. , Harmens Hendrik E. , Taylor Richard B.
Published: March 2003

A method for determining rates of ammonium assimilation in marine algae is described. Ammonium assimilation is defined as the decrease in total (medium + cellular) ammonium. The protonophore carbonyl cyanide m‐chlorophenylhydrazone (CCCP) was used to distinguish between uptake and assimilation of ammonium. Ammonium uptake by nitrogen‐replete and nitrogen‐starved cells of the diatom Phaeodactylum tricornutum Bohlin and the green macroalga Enteromorpha sp. was completely (98%–99%) inhibited in the presence of 100 μM CCCP. In addition to inhibiting further uptake of ammonium, CCCP promoted the release of unassimilated ammonium by nitrogen‐replete and nitrogen‐starved P. tricornutum and Enteromorpha that had been allowed to take up ammonium for a period. Most (97.5%) of preaccumulated 14C‐methylammonium was released by nitrogen‐starved P. tricornutum in the presence of CCCP. Specific rates of ammonium assimilation in nitrogen‐replete cultures of P. tricornutum were identical to the maximum growth rate, but specific rates in nitrogen‐starved cultures were fourfold greater. Rates of ammonium assimilation in Enteromorpha during both the surge and the internally controlled uptake phases were the same as the internally controlled rate of uptake, suggesting that the latter is a reliable measure of the maximum rate of assimilation.
CLADISTICS OF THE BRYOPSIDALES: A PRELIMINARY ANALYSIS
Authors: Vroom Peter S. , Smith Celia M. , Keeley Sterling C.
Published: March 2003

The Bryopsidales contains some of the most species rich and ecologically dominant algae in tropical ecosystems. However, the evolutionary relationships among the 29 genera and several hundred species of this order remain poorly resolved. Because of a lack of known reproductive characters for many taxa, evolutionary hypotheses grouped genera by similarities in morphological characters. To apply standard cladistical analyses to further our understanding of this group, this study presents the first comprehensive compilation of reported morphological, reproductive, and subcellular characteristics for genera in the Bryopsidales. Computer‐assisted cladistical analyses ultimately identified phylogenetically informative and uninformative characters. Although the topology of the trees generated in this study is expected to change as additional data are added to this matrix, many traditional groupings and recent groupings based on molecular data were supported.
THE DNA POLYMERASE GENE OF A BROWN ALGAL VIRUS: STRUCTURE AND PHYLOGENY
Authors: Lee Amy M. , Ivey Richard G. , Meints Russel H.
Published: March 2003

We have reported the complete sequence of the DNA polymerase gene from the virus that infected a filamentous brown alga, Feldmannia sp. (FsV). The DNA polymerase gene from FsV encoded 986 amino acids and contained all the conserved motifs of 3′‐5′ exonuclease domains and catalytic domains found in B‐family (α‐like) DNA polymerases. The codons for the FsV DNA polymerase appeared to have some bias toward guanine/cytosine (G/C) in the third position. The phylogenetic analysis of the FsV DNA polymerase gene and other viral DNA polymerase genes indicated that FsV belongs to a family of algal viruses recently defined as Phycodnaviridae.
DIEL PERIODICITY OF NITRATE REDUCTASE ACTIVITY AND PROTEIN LEVELS IN THE MARINE DIATOM THALASSIOSIRA WEISSFLOGII (BACILLARIOPHYCEAE)
Authors: Vergara Juan J. , Berges John A. , Falkowski Paul G.
Published: March 2003

The diel variation and regulation of the enzyme nitrate reductase (NR) were examined in the diatom Thalassiosira weissflogii (Gru.) Fryxell et Hasle. NR was purified, and polyclonal antibodies were raised to a 98‐kD polypeptide. The antibodies cross‐reacted only with proteins from closely related diatom species, suggesting significant epitopic variation of this enzyme within algal divisions. Neither NR enzymatic activity nor protein was detected in cells grown with ammonium as the sole nitrogen source; the addition of ammonium to cells growing on nitrate decreased both protein levels and enzyme activity by 40% within 2 h. In cells grown on a 12:12 h LD cycle, NR activity and NR protein levels were highly correlated, with a peak at midday, a decrease toward the end of the photoperiod, and an increase in activity beginning near the end of the dark period. The addition of actinomycin D (an inhibitor of RNA synthesis) and cycloheximide (an inhibitor of protein synthesis) affected NR activity and NR protein levels identically, strongly suggesting that this nuclear‐encoded protein is regulated primarily at a transcriptional level. The diel pattern of NR protein and activity ceased immediately following transfer to continuous light, indicating that the periodicity is not directly controlled by a circadian rhythm. Time‐lagged cross‐correlation analysis revealed a 6‐h phased difference between the minimum enzyme activity or protein levels and the maximum cellular carbon pool. On the basis of the experimental results, we develop a model proposing that (1) NR activity is regulated primarily by transcriptional regulation of NR synthesis and that (2) the level of expression of the enzyme during a given day is correlated with the integrated pool of organic carbon accumulated during the preceding photoperiod.
STUDIES ON POLYSACCHARIDES FROM THREE EDIBLE SPECIES OF NOSTOC (CYANOBACTERIA) WITH DIFFERENT COLONY MORPHOLOGIES: COMPARISON OF MONOSACCHARIDE COMPOSITIONS AND VISCOSITIES OF POLYSACCHARIDES FROM FIELD COLONIES AND SUSPENSION CULTURES
Authors: Huang Zebo , Liu Yongding , Paulsen Berit Smestad , Klaveness Dag
Published: March 2003

Hot water‐soluble polysaccharides were extracted from field colonies and suspension cultures of Nostoc commune Vaucher, Nostoc flagelliforme Berkeley et Curtis, and Nostoc sphaeroides Kützing. Excreted extracellular polymeric substances (EPS) were isolated from the media in which the suspension cultures were grown. The main monosaccharides of the field colony polysaccharides from the three species were glucose, xylose, and galactose, with an approximate ratio of 2:1:1. Mannose was also present, but the levels varied among the species, and arabinose appeared only in N. flagelliforme. The compositions of the cellular polysaccharides and EPS from suspension cultures were more complicated than those of the field samples and varied among the different species. The polysaccharides from the cultures of N. flagelliforme had a relatively simple composition consisting of mannose, galactose, glucose, and glucuronic acid, but no xylose, as was found in the field colony polysaccharides. The polysaccharides from cultures of N. sphaeroides contained glucose (the major component), rhamnose, fucose, xylose, mannose, and galactose. These same sugars were present in the polysaccharides from cultures of N. commune, with xylose as the major component. Combined nitrogen in the media had no qualitative influence on the compositions of the cellular polysaccharides but affected those of the EPS of N. commune and N. flagelliforme. The EPS of N. sphaeroides had a very low total carbohydrate content and thus was not considered to be polysaccharide in nature. The field colony polysaccharides could be separated by anion exchange chromatography into neutral and acidic fractions having similar sugar compositions. Preliminary linkage analysis showed that 1) xylose, glucose, and galactose were 1→4 linked, 2) mannose, galactose, and xylose occurred as terminal residues, and 3) branch points occurred in glucose as 1→3,4 and 1→3,6 linkages and in xylose as a 1→3,4 linkage. The polymer preparations from field colonies had higher kinematic viscosities than those from correspondingsuspension cultures. The high viscosities of the polymers suggested that they might be suitable for industrial uses.
PHYLOGENY OF THE BASAL LINEAGES OF STREPTOPHYTA BASED ON RBCL AND ATPB GENE SEQUENCE DATA
Authors: Karol K.G. , Delwiche C.F. , McCourt R.M.
Published: March 2003

The streptophytes comprise the Charophyceae sensu Mattox and Stewart (a morphologically diverse group of fresh‐water green algae) and the embryophytes (land plants). Several charophycean groups are currently recognized. These include the Charales, Coleochaetales, Chlorokybales, Klebsormidiales and Zygnemophyceae (Desmidiales and Zygnematales). Recently, SSU rRNA gene sequence data allied Mesostigma viride (Prasinophyceae) with the Streptophyta. Complete chloroplast sequence data, however, placed Mesostigma sister to all green algae, not with the streptophytes. Several morphological, ultrastructural and biochemical features unite these lineages into a monophyletic group including embryophytes, but evolutionary relationships among the basal streptophytes remain ambiguous. To date, numerous studies using SSU rRNA gene sequences have yielded differing phylogenies with varying degrees of support dependent upon taxon sampling and choice of phylogenetic method. Like SSU data, chloroplast DNA sequence data have been used to examine relationships within the Charales, Coleochaetales, Zygnemophyceae and embryophytes. Representatives of all basal streptophyte lineages have not been examined using chloroplast data in a single analysis. Phylogenetic analyses were performed using DNA sequences of rbcL (the genes encoding the large subunit of rubisco) and atpB (the beta‐subunit of ATPase) to examine relationships of basal streptophyte lineages. Preliminary analyses placed the branch leading to Mesostigma as the basal lineage in the Streptophyta with Chlorokybus, the sole representative of the Chlorokybales, branching next. Klebsormidiales and the enigmatic genus Entransia were sister taxa. Sister to these, the Charales, Coleochaetales, embryophytes and Zygnemophyceae formed a monophyletic group with Charales and Coleochaetales sister to each other and this clade sister to the embryophytes.