Maintenance of locomotor abilities following Laufband (treadmill) therapy in para- and tetraplegic persons: follow-up studies

Recent reports indicate that walking capabilities in spinal cord damaged persons significantly improve--as compared to conventional rehabilitation therapy--after intensive training of aided (Laufband) treadmill-stepping. In the present report, follow up investigations on two collectives of spinal cord injured (sci) persons are described who had undergone (Laufband) treadmill therapy either during a period of renewed rehabilitation months or years after spinal cord injury (35 chronic patients) or during their first postacute rehabilitation period (41 acute patients). Among the initially chronic patients, 20 from 25 still wheelchair-bound before the onset of (Laufband) treadmill therapy, ie not capable of raising from the wheelchair and walking without help by other persons, became independent walkers after therapy. Assessment of voluntary muscle activity in resting position before and after the period of therapy had shown only small increases in most patients, indicating the involvement of motor automatisms and better utilisation of remaining muscle function during walking. Follow-up assessments performed 6 months to 6 1/2 years after discharge from the hospital revealed that the walking capabilities achieved by (Laufband) treadmill therapy in the 35 initially chronic patients were maintained in 31 persons, in three they had further improved, in only one it was reduced. These results indicate that the improvements achieved under clinical conditions can be maintained in every day life under domestic surroundings. From 41 initially acute patients, 15 had further improved and none had reduced his walking capability 6 months to 6 years after discharge from the hospital.     

A regulatory mutant of Hansenula polymorpha exhibiting methanol utilization metabolism and peroxisome proliferation in glucose

Mutant LGM-128 of Hansenula polymorpha harbors the recessive mutation glr2-1 which confers a complex pleiotropic phenotype, the major feature of which is the metabolically unnecessary induction of methanol utilization metabolism (C1 metabolism) during growth on glucose, whether or not methanol is in the medium. Therefore, in this mutant, peroxisomes are formed and proliferate upon cultivation in glucose-containing media. In these media, LGM-128 shows induction levels of C1 metabolism that are similar to those observed in methanol-containing media. This indicates that GLR2 controls the repression-derepression process stimulated by glucose and that the induction process triggered by methanol plays only a minor role in activating C1 metabolism. Cultivating LGM-128 in methanol and then transferring it to glucose media revealed that active degradative processes occur, leading to the disappearance of C1 metabolism. This observation suggests that, although stimulated by glucose, the two processes are controlled by elements which are, at least in part, distinct. Finally, glr2-1 does not affect ethanol repression, suggesting that in H. polymorpha the two repressing circuits are separated.     

A molecular mechanism for signaling between seven-transmembrane receptors: evidence for a redistribution of G proteins

Although activation of one seven-transmembrane receptor can influence the response of a separate seven-transmembrane receptor, e. g., the phenomenon of synergism, the underlying mechanism(s) for this signaling process is unclear. The present study investigated communication between two receptors that exhibit classical synergism, e.g., human platelet thrombin and thromboxane A2 receptors. Activation of thrombin receptors caused an increase in ligand affinity of thromboxane A2 receptors. This effect (i) was shown to be specific, since a similar increase in ligand affinity was not caused by ADP or A23187; (ii) did not require cytosolic components, e.g., kinases, proteases, phosphatases, etc., because it occurred in isolated platelet membranes; (iii) was G protein-mediated because it was blocked by an Galphaq C terminus antibody; and (iv) was associated with a net increase in Galphaq coupling to thromboxane A2 receptors. Collectively, these data provide evidence that seven-transmembrane receptors that share a common Galpha subunit can communicate with each other via a redistribution of their G proteins. Thus, activation of thrombin receptors increases Galphaq association with thromboxane A2 receptors thereby shifting them to a higher affinity state. This signaling phenomenon, which modulates receptor-ligand affinity, may serve as a molecular mechanism for cellular adaptive processes such as synergism.     

Psychological stress and glucose metabolism in obese and normal-weight subjects: A possible mechanism for differences in stress-induced eating.

Compared 10 obese Ss (mean age 51.7 yrs) and 10 age- and sex-matched normal-weight controls in 2 counterbalanced sessions (stress and nonstress). At each session, Ss were fed a carbohydrate load, and glucose was measured 0, 30, 60, 90, and 120 min after the load. On nonstress days, Ss relaxed after the drink; on stress days, Ss participated in 30 min of competitive tasks. The stressor significantly delayed glucose response in normal-weight Ss but did not affect glucose response in obese Ss. This finding may have implications for differences between obese and normal-weight individuals in stress-induced eating, possibly explaining the decreased consumption of normal-weight individuals during stress. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of troglitazone and metformin on glucose and lipid metabolism: alterations of two distinct molecular pathways

Using an experimental model of rat colon adenocarcinoma, we have recently shown that the presence of H blood-group antigen on variants of the CD44 adhesion molecule carrying amino acids encoded by exon v6 (CD44v6), increased the cells' tumorigenicity. In the present study, colon adenocarcinomas were induced by 1,2-dimethylhydrazine treatment in rats. Using immunohistochemistry, biopsies of normal, precancerous and carcinomatous colon mucosa were evaluated for expression A and H blood group antigens and CD44s and CD44v6 antigens. Normal rat colon showed strong and homogeneous expression of blood-group antigen A, but weak expression of H antigen. Several weeks before the appearance of tumours, dysplastic glands were strongly stained with anti-H reagents, while their A antigen was lost. Expression of CD44v6 was weak and restricted to some cells at the bottom of normal crypts. No obvious change was observed before appearance of severe dysplasia. In carcinomas, a strong but irregular expression of A, H and CD44v6 antigens was observed. In moderately differentiated carcinomas, A and H antigens were present at the apical surface of cells, whereas CD44v6 was found at the basolateral side. Only carcinomatous cells with loss of polarity, found in poorly differentiated cancers or infiltrated in the muscularis mucosae, were found to coexpress blood-group H or A and CD44v6 antigens at their surface.     

A protein involved in co-ordinated regulation of inorganic carbon and glucose metabolism in the facultative photoautotrophic cyanobacterium Synechocystis PCC6803

The involvement of a gene of Synechocystis PCC6803, icfG, in the co-ordinated regulation of inorganic carbon and glucose metabolism, was established. The icfG gene codes for a 72 kDa protein, which shows no homology with those registered in data libraries. Expression of icfG required glucose, the actual inducer probably being glucose-6-phosphate, and was independent of light and of the external inorganic carbon concentration. Mutants carrying an inactivated copy of icfG were constructed. Their growth characteristics were identical to those of the wild type under all regimes except in limiting inorganic carbon with glucose being present either before or after the transfer to the limiting conditions. These conditions completely prevented growth, both in the light and in the dark. The inhibition could be relieved by several intermediates of the tricarboxylic acid cycle. Assays of various enzymic activities related to inorganic carbon uptake and to its assimilation via either the Calvin cycle or phosphoenolpyruvate carboxylase did not reveal the level of action of IcfG. Possible models include a blockage of the assimilation of both carbon sources in the absence of IcfG, or the inhibition of Ci incorporation route(s) essential under limiting inorganic carbon conditions, even when glucose is present, and even in the dark.     

Intestinal uptake of uridine in suckling rats: mechanism and ontogeny

Nucleosides, essential substrates for a variety of intracellular metabolic reactions, are obtained from dietary and endogenous sources. Nucleotides (which dephosphorylate to nucleosides prior to intestinal absorption) are present in milk and have trophic effects on the developing gastrointestinal tract. The mechanism of transport of nucleosides in the developing intestine of suckling rats is unknown. To address this issue, we therefore examined uridine uptake in rat everted intestinal sacs. In suckling rats (15-17 days old), tissue uptake of low (5-microM) and high (60 microM) concentrations of [3H]-uridine was linear for up to 2 min of incubation. Initial rate of uptake of [3H]-uridine was (i) not significantly different in the jejunum and the ileum; (ii) greater in the presence of Na+, than other cations; (iii) saturable as a function of concentration with a Vmax of 21,044 +/- 2,302 pmol/g tissue wet wt/30 sec and an apparent Km of 33.8 +/- 10.1 microM; (iv) inhibited by high concentration (500 microM) of unlabeled uridine and other nucleosides; (v) temperature-dependent; (vi) energy-dependent; and (vii) pH-sensitive. Developmental maturation was associated with a progressive decrease in the Vmax of the uridine transport process (21,044 +/- 2,302, 14,651 +/- 1,679, and 8,461 +/- 1,369 pmol/g tissue wet wt/30 sec for suckling, weanling, and adult rats, respectively) and a progressive increase in the apparent Km of the uptake system (33.8 +/- 10.1, 55.6 +/- 13.1, and 61.7 +/- 14.5 microM for suckling, weanling, and adult rats, respectively). We concluded that uptake of uridine by the developing intestine of suckling rats involves a carrier-mediated system, which is energy- and temperature-dependent, and requires extracellular sodium. Furthermore, the uptake process was found to undergo clear ontogenic changes with maturation.     

Degradative activity of granzyme A on skeletal muscle proteins in vitro: a possible molecular mechanism for muscle fiber damage in polymyositis

The importance of cytotoxic T lymphocytes (CTLs) in the autoimmune inflammatory myopathies, especially polymyositis (PM), has been emphasized. We have studied the degradative activity of granzyme A, a cytotoxic molecule with trypsin-like specificity in CTL granules, on several muscle proteins in vitro. Our study reveals that granzyme A hydrolyzes dystrophin, myosin, and nebulin, but not laminin, alpha-actinin, vinculin, and connectin in vitro. Among these proteins, nebulin is more susceptible to proteolysis, followed by dystrophin, myosin heavy chain, and myosin light chains, in that order. This result implies an important role of granzyme A in CTL-mediated muscle fiber damage in PM.     

Heat shock proteins and molecular chaperones: implications for adaptive responses in the skin

Recent advances in the biology of heat-shock proteins (hsps) are reviewed. These abundant and evolutionarily highly conserved proteins (also called stress proteins) act as molecular escorts. Hsps bind to other cellular proteins, help them to fold into their correct secondary structures, and prevent misfolding and aggregation during stress. Cytoplasmic hsp70 and hsp60 participate in complicated protein-folding pathways during the synthesis of new polypeptides. Close relatives of hsp70 and hsp60 assist in the transport and assembly of proteins inside intracellular organelles. Hsp90 may have a unique role, binding to the glucocorticoid receptor in a manner essential for proper steroid hormone action. Hsps may also be essential for thermotolerance and for prevention and repair of damage caused by ultraviolet B light. A unique class of T lymphocytes, the gamma delta T cells, exhibits a restricted specificity against hsps. These T cells may constitute a general, nonspecific immune mechanism directed against the hsps within invading organisms or against very similar hsps within invading organisms or against very similar hsps expressed by infected (stressed) keratinocytes. Immunologic cross-reactivity between hsps of foreign organisms and of the host may play a role in some autoimmune diseases. Although hsps are expressed in the skin, many questions remain about their role during injury, infection, and other types of cutaneous pathophysiology.     

Normal glucose-induced suppression of glucose production but impaired stimulation of glucose disposal in type 2 diabetes: evidence for a concentration-dependent defect in uptake

The present studies were undertaken to determine whether people with type 2 diabetes are resistant to the effects of glucose as well as insulin. Diabetic and nondiabetic subjects were studied on three occasions. Hormone secretion was inhibited with somatostatin. Insulin concentrations were kept at "basal" levels (referred to as low insulin infusion) from 0 to 180 min then increased to approximately 200 pmol/l from 181 to 360 min (referred to as high insulin infusion). Glucose concentrations were clamped at either approximately 95, approximately 130, or approximately 165 mg/dl on each occasion. In the presence of basal insulin concentrations, a progressive increase in glucose from 95 to 130 to 165 mg/dl was accompanied by a comparable and progressive decrease (P = 0.001 to 0.003 by analysis of variance [ANOVA]) in endogenous glucose production (measured with [6-(3)H]glucose) and total glucose output (measured with [2-(3)H]glucose) and incorporation of 14CO2 into glucose (an index of gluconeogenesis) in both diabetic and nondiabetic subjects, indicating normal hepatic (and perhaps renal) response to glucose. In the nondiabetic subjects, an increase in glucose concentration from 95 to 130 to 165 mg/dl resulted in a progressive increase in glucose disappearance during both the low (19.9 +/- 1.8 to 23.6 +/- 1.8 to 25.4 +/- 1.6 micromol x kg(-1) x min(-1); P = 0.003 by ANOVA) and high (36.4 +/- 3.1 to 47.6 +/- 4.5 to 61.1 +/- 7.0 micromol x kg(-1) x min(-1); P = 0.001 by ANOVA) insulin infusions. In contrast, in the diabetic subjects, whereas an increase in glucose from 95 to 130 mg/dl resulted in an increase in glucose disappearance during both the low (P = 0.001) and high (P = 0.01) dose insulin infusions, a further increase in glucose concentration to 165 mg/dl had no further effect (P = 0.41 and 0.38) on disappearance at either insulin dose (low: 14.2 +/- 0.8 to 18.2 +/- 1.1 to 18.7 +/- 2.4 micromol x kg(-1) x min(-1); high: 21.0 +/- 3.2 to 33.9 +/- 6.4 to 32.5 +/- 8.0 micromol x kg(-1) x min(-1) for 95, 130, and 165 mg/dl, respectively). We conclude that whereas glucose-induced stimulation of its own uptake is abnormal in type 2 diabetes, glucose-induced suppression of endogenous glucose production and output is not. The abnormality in uptake occurs in the presence of both basal and high insulin concentrations and is evident at glucose concentrations above but not below 130 mg/dl, implying a defect in a glucose-responsive step.     

G-protein-coupled receptors: molecular mechanisms involved in receptor activation and selectivity of G-protein recognition

Asian students of seven Japanese language schools participated, and data of 292 Chinese, Taiwanese, and Korean students were analyzed in this study. They were asked about (1) attitudes toward their own and other cultures, (2) high regard for their country and culture, (3) self-efficacy and social skills at the moment and when they were in their country, (4) aspired level of social skills in this country, and (5) feeling of adjustment to life in Japan. Main findings were as follows: (1) psychological factors had stronger effects on the feeling than demographic factors. Self-efficacy in particular had a strong effect. (2) Attitudes to own and other cultures were related to self-efficacy and the feeling. (3) Structural analysis revealed a difference in the feeling between students from socialist and capitalist regions. Based on the analysis, a causal model was proposed of psychological and demographic factors leading to feeling of adjustment, and Asian students' adjustment to life in Japan was discussed in terms of adjustment to their inner, psychological environment.     

Decreased glucose metabolism causes separation of hoof lamellae in vitro: a trigger for laminitis?

Explants of horses' hooves remained intact for up to 8 days when incubated in Dulbecco's modified Eagle medium (D-MEM) containing 25 mmol/l glucose but separated within 36 h when incubated in saline. The separation occurred between the basal epidermal cells and their basement membrane which is characteristic of the hoof separation that occurs in laminitis. Separation of hoof explants was prevented by addition of glucose to saline and was induced by adding 2-deoxyglucose or aminophenylmercuric acetate to D-MEM. Glucose consumption by the hoof explants was inhibited by 2-deoxyglucose and aminophenylmercuric acetate. The explants consumed relatively large amounts of glucose during the first 2 days of incubation and then little over the next 6 days. Despite the reduced glucose consumption, the hoof explants did not separate over 8 days of incubation. The results indicated that the integrity of the hoof explants was initially dependent on consumption of glucose and provide a possible explanation for the development of laminitis caused by conditions such as carbohydrate overload, acute inflammatory conditions, corticosteroid therapy and hyperlipidaemia. It would be expected that these conditions would induce a major hormonally-mediated metabolic shift away from glucose consumption by many peripheral tissues. It is suggested, therefore, that if the metabolic change occurred faster than the hoof tissue could adapt to an alternative energy substrate, then hoof separation and laminitis would occur.     

Gonadotropin-releasing hormone receptor couples to multiple G proteins in rat gonadotrophs and in GGH3 cells: evidence from palmitoylation and overexpression of G proteins

Nicotinamide-adenine-dinucleotide-phosphate-diaphorase (NADPH-d) histochemistry has been applied in the present study to determine the distribution of putative nitric oxide (nitric oxide synthase)-producing cells during embryonic and early postembryonic development in the pond snail, Lymnaea stagnalis L., with special reference to the nervous system. The first NADPH-d-positive structures appear as early as 18% of development (E18, trochophore stage) and correspond to the pair of protonephridia. These structures later show disintegration, although after metamorphosis (E26=75%) staining of their individually spreading cells can be observed until hatching. Peripheral sensory neurons in the foot, mantle edge and lips, and their afferents projecting to the central nervous system reveal NADPH-d activity in the postmetamorphosis period (E25-E27=E60%-E80%) of embryogenesis. After hatching (P1-P3), a number of stained sensory cells appear in the pharynx and esophagus. Some NADPH-d positive neuronal perikarya occur in the pedal and pleural ganglia, and a few weakly stained cells in the cerebral and buccal ganglia of juvenile snails. At the same time, a continuous bundle of reactive fibers is formed in the neuropil both through and through around the circumesophageal ganglion ring. The localization of NADPH-d activity in the developing nervous system of Lymnaea suggests that nitric oxide participates mainly in sensory processes. However, its role in specific intraganglionic integrative events cannot be excluded following embryonic metamorphosis.     

Evolutionary relationship of uptake systems for biopolymers in Escherichia coli: cross-complementation between the TonB-ExbB-ExbD and the TolA-TolQ-TolR proteins

Escherichia coli possesses two energy-coupled import systems through which substances of low concentration and of a size too large to permit diffusion through the porins are translocated across the outer membrane. Group B colicins, ferric siderophores and vitamin B12 are taken up via the TonB-ExbB-ExbD, group A colicins via the TolA-TolQ-TolR system. Cross-complementation between the two systems was demonstrated in that tolQ tolR mutants transformed with plasmids carrying exbB exbD became sensitive to group A colicins, and exbB exbD mutants transformed with plasmid-encoded tolQ tolR became sensitive to group B colicins. TolQ-TolR interacted through TonB, and ExbB-ExbD interacted through TolA with the outer membrane receptors and colicins. Activity of ExbB ExbD via TolA was higher in cells lacking TonB, and activity of TolQ TolR via TonB was increased when TolA was missing. The very distinct TolA and TonB proteins mediate exclusive interaction with group A and group B receptors, respectively. ExbB-TolR and ExbD-TolQ mixtures showed little if any complementation of exbB exbD and tolQ tolR mutants indicating coevolution of ExbB with ExbD and TolQ with TolR. Sequence homology and mutual functional substitution of ExbB-ExbD and TolQ-TolR suggest the evolution of the two import systems from a single import system.     

O-GlcNAcylation of key nuclear and cytoskeletal proteins: reciprocity with O-phosphorylation and putative roles in protein multimerization

BACKGROUND: Registered mortality from cryptogenic fibrosing alveolitis (CFA) in England and Wales has increased substantially since the specific International Classification of Diseases code for CFA was introduced in 1979. However, since a significant proportion of deaths from CFA are misclassified as post inflammatory fibrosis (PIF), it is possible that the observed rise in CFA mortality is due to diagnostic transfer from this code. To investigate this, and to assess mortality trends in other countries, annual CFA and PIF mortality data from England and Wales, USA, Australia, Scotland, Canada, New Zealand, and Germany were analysed. METHODS: Crude annual mortality rates were calculated and rates standardised by Poisson regression to allow assessment of changes over time and comparison between countries, sexes, and age groups. The relative trends in mortality from CFA and PIF were assessed by calculating the annual ratio of CFA to PIF deaths. RESULTS: Men were more likely than women to die from both CFA and PIF in all countries. The highest standardised CFA mortality rate occurred in England and Wales, and the lowest in Germany. Since 1979 mortality from CFA has increased in England and Wales, Australia, Scotland and Canada, but there was no trend in CFA mortality in New Zealand or Germany. In the USA mortality from CFA was low and has fallen. Mortality from PIF increased in all countries except New Zealand and Germany, and the highest PIF mortality, together with the greatest increase over time, was seen in the USA. Changes over time in the annual ratio of CFA to PIF deaths in all countries were small, implying that diagnostic transfer is not a major cause of the increasing CFA mortality. CONCLUSIONS: Mortality from CFA continues to increase in England and Wales and in many other countries. Diagnostic transfer from PIF does not appear to be a major cause of this.     

Iron-dependent oxidation, ubiquitination, and degradation of iron regulatory protein 2: implications for degradation of oxidized proteins

The ability of iron to catalyze formation of reactive oxygen species significantly contributes to its toxicity in cells and animals. Iron uptake and distribution is regulated tightly in mammalian cells, in part by iron regulatory protein 2 (IRP2), a protein that is degraded efficiently by the proteasome in iron-replete cells. Here, we demonstrate that IRP2 is oxidized and ubiquitinated in cells before degradation. Moreover, iron-dependent oxidation converts IRP2 into a substrate for ubiquitination in vitro. A regulatory pathway is described in which excess iron is sensed by its ability to catalyze site-specific oxidations in IRP2, oxidized IRP2 is ubiquitinated, and ubiquitinated IRP2 subsequently is degraded by the proteasome. Selective targeting and removal of oxidatively modified proteins may contribute to the turnover of many proteins that are degraded by the proteasome.