Motor nerve terminal degeneration provides a potential mechanism for rapid recovery in acute motor axonal neuropathy after Campylobacter infection

We investigated the possible mechanisms of paralysis and recovery in a patient with the acute motor axonal neuropathy (AMAN) pattern of the Guillain-Barré syndrome. The AMAN pattern of GBS is characterized clinically by acute paralysis without sensory involvement and electrodiagnostically by low compound motor action potential amplitudes, suggesting axonal damage, without evidence of demyelination. Many AMAN patients have serologic or culture evidence of recent Campylobacter jejuni infection. Pathologically, the most severe cases are characterized by wallerian-like degeneration of motor axons affecting the ventral roots as well as peripheral nerves, but some fatal cases have only minor changes in the roots and peripheral nerves, and some paralyzed patients with the characteristic electrodiagnostic findings of AMAN recover rapidly. The mechanism of paralysis and recovery in such cases has been uncertain. A 64-year-old woman with culture-proven Campylobacter upsaliensis diarrhea developed typical features of AMAN. She improved quickly following plasmapheresis. Her serum contained IgG anti-GM1 antibodies. The lipopolysaccharide of the organism bound peanut agglutinin. This binding was blocked by cholera toxin, suggesting that the organism contained the Gal(beta1-3)GalNAc epitope of GM1 in its lipopolysaccharide. Motor-point biopsy showed denervated neuromuscular junctions and reduced fiber numbers in intramuscular nerves. In contrast, the sural nerve biopsy was normal and skin biopsy showed normal dermal and epidermal innervation. In AMAN the paralysis may reflect degeneration of motor nerve terminals and intramuscular axons. In addition, the anti-GM1 antibodies, which can bind at nodes of Ranvier, might produce failure of conduction. These processes are potentially reversible and likely to underlie the capacity for rapid recovery that characterizes some cases of AMAN.     

The murine Ext1 gene shows a high level of sequence similarity with its human homologue and is part of a conserved linkage group on chromosome 15

We have cloned and sequenced the murine homologue of the human EXT1 gene. At the protein level, these genes show almost complete identity as divergence is limited to only 5 amino acid positions that are scattered about the whole sequence. In addition, similarity searches identified a protein from chromosome III of C. elegans that shows significant similarity to the human and murine EXT/Ext genes. Using high resolution backcross mapping, the murine Ext1 was mapped at 26.55 cM between D15Mit143 and D15Mit153 on mouse chromosome 15. Therefore, Ext1 is part of an evolutionarily conserved linkage group including SDC2/Hspg1, TRHR/Trhr, EXT1/Ext1, MYC/Myc, and TG/Tgn.     

Long-term follow-up of cytostatic intravesical instillation in patients with superficial bladder carcinoma. Is short-term, intensive instillation better than maintenance therapy?

Change of road user attitudes is often advocated as a necessary condition for improvement of road safety. The relation between road user attitudes and accident risk is, however, not well known in road safety research. The objective of this study was to find out whether attitudes are of importance to road safety, i.e. the hypothesis is that drivers having attitudes considered correct according to the traffic code, have lower accident risk than other drivers. The attitudes of a representative sample of Norwegian driver's license holders as well as their accident involvement and driving distance were surveyed by mail questionnaires in two phases. When no other factor is taken into account, accident risk is found to be affected by driver attitudes. When, on the other hand, the age of drivers is taken into account, the relation between attitudes and accident risk disappears. It is concluded that age and annual mileage are more important to accident risk than are attitudes, and more knowledge of the relationship between attitudes and road accident risk is needed.     

Laser-induced photoacoustic effects in the dentin]

To study photoacoustic effects in dentin caused by UV-laser ablation, laser-induced shockwaves were measured using piezoelectric PVDF films. Above the tissue-specific energy threshold for photoablation the amplitude of the acoustic shock waves is proportional to the applied laser energy density. Laser energy densities of 2 J/cm2 cause pressure amplitudes of 50 bar, densities of 20 J/cm2 cause pressure amplitudes of 1000 bar. To avoid microcracks in dentine the maximum laser energy density to prepare dentin should be limited to approximately 20 J/cm2.     

Identification of novel drug resistance-associated proteins by a panel of rat monoclonal antibodies

It is well established that the rabbit corpus luteum (CL) function depends upon endogenous oestradiol, the major source of which in the rabbit ovary is considered to be the ovarian follicles. The absence of oestradiol formation by the rabbit CL has been previously reported. In a hyperstimulated pseudopregnant rabbit model used in our laboratory which developed a large number of corpora lutea in response to chorionic gonadotrophin (eCG)/hCG, we observed the survival of corpora lutea in vivo, and normal levels of plasma progesterone throughout pseudopregnancy (PP), despite the scarcity or the absence of follicles as a source of the luteotrophic hormone. Measurement of oestradiol in the plasma indicated that it was at high levels and correlated with the number of corpora lutea. This led us to investigate the luteal origin of oestradiol in this model. PP was induced in rabbits by i.m. injection of 200 IU eCG daily for 2 days followed on day 4 by i.m. injection of 200 IU hCG (day 0 of PP). Luteal tissue obtained at days 5, 9 and 12 of PP and cultured for 24 h synthesized oestradiol and testosterone in addition to progesterone. However, under the same conditions, follicles had limited capacity to secrete oestradiol. The presence of an aromatase activity in luteal tissue was confirmed when exogenous testosterone was added to the culture medium. P450aromatase (P450arom) mRNA was found in luteal tissue at days 5, 9 and 12 of PP. Small or large luteal cells, obtained by enzymatic digestion of the tissue followed by centrifugation in a Percoll density gradient, were cultured during several days with or without gonadotrophin or dibutyryl cAMP (dbcAMP). Both types of cells secreted oestradiol. In small cells and luteal tissue, aromatase activity was stimulated (1.5-2-fold) by hCG and dbcAMP. Large cells exhibited a greater capacity to aromatize testosterone than small cells, but aromatase activity was not modified by hCG or by dbcAMP. FSH had no effect on aromatase activity of either luteal cell type. This intrinsic luteal tissue aromatase capacity and the absence of premature regression of corpora lutea despite the limited support of follicular oestrogen, suggest an autocrine and luteotrophic role for this luteal oestrogen.     

Transplantation of hematopoietic stem cells. II: Indications for transplantation of hematopoietic stem cells after myeloablative therapy

The destruction of hematopoiesis and lymphopoiesis by total body irradiation or high dose chemotherapy for the treatment of malignancy can be reversed by the transplantation of allogeneic or autologous hematopoietic stem cells. In primary disorders of bone marrow or immune system, allogeneic stem cells replace deficient cells. Acute leukemias can be cured, with in 50 to 80% disease free survival after 5 to 8 years. The allogeneic graft versus leukemia effect by immunoreactive cells reduces the relapse rate in myeloid and lymphoid malignancies. 40 to 70% of patients with chronic myeloid leukemia remain disease free after more than 5 years. Patients with malignant lymphoma have a 40 to 70% chance of cure with autologous transplantation, which is not increased by allogeneic cells, because of a higher incidence of severe complications. An increasing number of patients without option for cure is treated with the aim of prolonging remission or retarding disease progression, such as in chronic myeloid leukemia, multiple myeloma and certain solid tumors. New studies suggest in breast cancer with axillary lymph node metastases, that adjuvant high dose chemotherapy with autologous stem cell support will significantly improve disease free survival from 30 to over 60% after 3 to 5 years. In congenital metabolic and storage diseases deficient enzymes are substituted by the allogeneic cells. Clinical trials explore the use of stem cell transplantation after myeloablative therapy in autoimmune disorders as well as in gene therapy with transfected hematopoietic stem cells.     

Pharmacokinetic-pharmacodynamic modelling of the anti-lipolytic and anti-ketotic effects of the adenosine A1-receptor agonist N6-(p-sulphophenyl)adenosine in rats

1. The purpose of this study was to develop and validate an integrated pharmacokinetic-pharmacodynamic model for the anti-lipolytic effects of the adenosine A1-receptor agonist N6-(p-sulphophenyl)adenosine (SPA). Tissue selectivity of SPA was investigated by quantification of haemodynamic and anti-lipolytic effects in individual animals. 2. After intravenous infusion of SPA to conscious normotensive Wistar rats, arterial blood samples were drawn for determination of blood SPA concentrations, plasma non-esterified fatty acid (NEFA) and beta-hydroxybutyrate levels. Blood pressure and heart rate were monitored continuously. 3. The relationship between the SPA concentrations and the NEFA lowering effect was described by the indirect suppression model. Administration of SPA at different rates and doses (60 microg kg[-1] in 5 min and 15 min, and 120 microg kg[-1] in 60 min) led to uniform pharmacodynamic parameter estimates. The averaged parameters (mean+/-s.e., n=19) were Emax: -80+/-2% (% change from baseline), EC50: 22+/-2 ng ml(-1), and Hill factor: 2.2+/-0.2. 4. In another group, given 400 microg kg(-1) SPA in 15 min, pharmacodynamic parameters for both heart rate and anti-lipolytic effect were derived within the same animal. The reduction in heart rate was directly related to blood concentration on the basis of the sigmoidal Emax model. SPA inhibited lipolysis at concentrations lower than those required for an effect on heart rate. The EC50 values (mean+/-s.e., n=6) were 131+/-31 ng ml(-1) and 20+/-3 ng ml(-1) for heart rate and NEFA lowering effect, respectively. 5. In conclusion, the relationship between blood SPA concentrations and anti-lipolytic effect was adequately described by the indirect suppression model. For SPA a 6 fold difference in potency was observed between the effects on heart rate and NEFAs, indicating some degree of tissue selectivity in vivo.     

Tolerance to diazepam and changes in GABA(A) receptor subunit expression in rat neocortical areas

Long-term treatment with diazepam, a full allosteric modulator of the GABA(A) receptor, results in tolerance to its anticonvulsant effects, whereas an equipotent treatment with the partial allosteric modulator imidazenil does not produce tolerance. Use of subunit-specific antibodies linked to gold particles allowed an immunocytochemical estimation of the expression density of the alpha1, alpha2, alpha3, alpha5, gamma(2L&S) and beta(2/3) subunits of the GABA(A) receptor in the frontoparietal motor and frontoparietal somatosensory cortices of rats that received long-term treatment with vehicle, diazepam (three times daily for 14 days, doses increasing from 17.6 to 70.4 micromol/kg), or imidazenil (three times daily for 14 days, doses increasing from 2.5 to 10.0 micromol/kg). In this study, tolerance to diazepam was associated with a selective decrease (37%) in the expression of the alpha1 subunit in layers III-IV of the frontoparietal motor cortex, and a concomitant increase in the expression of the alpha5 (150%), gamma(2L&S) and beta(2/3) subunits (48%); an increase in alpha5 subunits was measured in all cortical layers. In the frontoparietal somatosensory cortex, diazepam-tolerant rats had a 221% increase in the expression of alpha5 subunits in all cortical layers, as well as a 35% increase in the expression of alpha3 subunits restricted to layers V-VI. Western blot analysis substantiated that these diazepam-induced changes reflected the expression of full subunit molecules. Rats that received equipotent treatment with imidazenil did not become tolerant to its anticonvulsant properties, and did not show significant changes in the expression of any of the GABA(A) receptor subunits studied, with the exception of a small decrease in alpha2 subunits in cortical layers V-VI of the frontoparietal somatosensory cortex. The results of this study suggest that tolerance to benzodiazepines may be associated with select changes in subunit abundance, leading to the expression of different GABA(A) receptor subtypes in specific brain areas. These changes might be mediated by a unique homeostatic mechanism regulating the expression of GABA(A) receptor subtypes that maintain specific functional features of GABAergic function in cortical cell layers.     

Assembly of an abundant endogenous major histocompatibility complex class II/peptide complex in class II compartments

To identify the intracellular site(s) of formation of an endogenous class II/peptide complex in a human B cell line, we employed kinetic pulse-chase labeling experiments followed by subcellular fractionation by Percoll density gradient centrifugation and immunogold labeling on ultrathin cryosections. For direct demonstration of assembly of such complexes, we used the monoclonal antibody YAe, which detects an endogenous complex of the mouse class II molecule I-Ab with a 17-amino acid peptide derived from the alpha chain of HLA-DR (DR alpha52-68). We show that in human B lymphocytes, these class II/peptide complexes assemble and transiently accumulate in major histocompatibility complex class II-enriched compartments before reaching the cell surface.