Comparison of the pharmacological profile of S-nitrosothiols, nitric oxide and the nitrergic neurotransmitter in the canine ileocolonic junction

1. In organ bath experiments, hydroquinone (30-100 microM) and hydroxocobalamin (30-100 microM) concentration-dependently inhibited the relaxations induced by NO (0.3-30 microM) but not those by nitroglycerin (GTN, 1 microM) in the canine ileocolonic junction (ICJ). Hydroxocobalamin reduced the relaxation to low frequency (2 Hz) stimulation of the non-adrenergic, non-cholinergic (NANC) nerves, whereas hydroquinone only reduced the NANC nerve-mediated relaxations to electrical stimulation at 16 Hz, 0.5 ms. 2. Relaxations to S-nitroso-L-cysteine (CysNO, 1-30 microM), or S-nitroso-N-acetyl-D,L-penicillamine (SNAP, 1-30 microM) were not inhibited by hydroquinone (30-100 microM), hydroxocobalamin (30-100 microM), pyrogallol (30-100 microM) or L-cysteine (1-3 microM). Hydroquinone (100 microM) only reduced the relaxation to 10 microM CysNO. Hydroxocobalamin, but not hydroquinone, pyrogallol or L-cysteine, potentiated the relaxations to the lowest concentration (1 microM) of S-nitrosoglutathione (GSNO, 1-30 microM). 3. In the superfusion bioassay, hydroquinone (100 microM) and hydroxocobalamin (1 microM) concentration-dependently inhibited the biological activity of authentic NO (1-4 pmol) to the same extent as that of the transferable nitrergic factor, released from the canine ICJ in response to NANC nerve stimulation (8-16 Hz, 2 ms). Responses to GTN (10 pmol) or adenosine 5'-triphosphate (10 nmol) were not affected. 4. In conclusion, the nitrosothiols CysNO, SNAP and GSNO relax the canine ileocolonic junction, but these relaxations, pharmacologically, behave differently from the NANC nerve-mediated relaxations. From the bioassay experiments, we conclude that the nitrergic factor, released in response to NANCnerve stimulation of the canine ICJ, behaves pharmacologically like NO but not like a nitrosothiol.Therefore, we suggest NO, and not CysNO, SNAP or GSNO as the inhibitory NANC neurotransmitter in the canine ICJ.     

Genetic basis for diabetes resistance in NOD/Wehi mice

The basis for diabetes resistance in low diabetes incidence NOD/Wehi mice was examined in a breeding study. NOD/Wehi mice were crossed with high diabetes incidence NOD/Lt mice producing F1 hybrid mice which expressed a low incidence of diabetes. To distinguish between genetic and environmental causes for diabetes resistance, these F1 mice were backcrossed to NOD/Lt mice resulting in BC1 hybrid mice which expressed an intermediate incidence of diabetes. Similar results were obtained by examining the severity of insulitis in the hybrid mice. As both the incidence of diabetes and severity of insulitis in the hybrid mice were consistent with a single dominant gene mediating diabetes resistance, an attempt to localize this gene was made. Although over 140 loci which display polymorphism amongst inbred strains were typed in both parental lines, only a single locus, D8Mit9, was found to differ. As heterozygotes at D8Mit9 were not over represented amongst 45 diabetic BC1 hybrid mice examined, it was concluded that a resistance gene was not linked to this locus.     

Cancer genetics, cytogenetics--defining the enemy within

BACKGROUND/AIMS: International comparisons of clinical practice may help in assessing the magnitude and possible causes of variation in cross national healthcare utilisation. With this aim, the indications for cataract surgery in the United States, Denmark, the province of Manitoba (Canada), and the city of Barcelona (Spain) were compared. METHODS: In a prospective multicentre study, patients scheduled for first eye cataract surgery and aged 50 years or older were enrolled consecutively. From the United States 766 patients were enrolled; from Denmark 291; from Manitoba 152; and from Barcelona 200. Indication for surgery was measured as preoperative visual status of patients enlisted for cataract surgery. Main variables were preoperative visual acuity in operative eye, the VF-14 score (an index of functional impairment in patients with cataract) and ocular comorbidity. RESULTS: Mean visual acuity were 0.23 (USA), 0.17 (Denmark), 0.15 (Manitoba), and 0.07 (Barcelona) (p < 0.001). When restricting the sample to eyes with normal retina and macula, no significant difference between United States and Denmark was observed (p > 0.05). Mean VF-14 scores were 76 (USA), 76 (Denmark), 71 (Manitoba), and 64 (Barcelona) (p < 0.001). CONCLUSION: Similar indications for cataract surgery were found in the United States and Denmark. Significantly more restricted indications were observed in Manitoba and Barcelona. Possible explanations for the results are discussed, including differences in sociodemographic characteristics, access to care, surgeons' willingness to operate, and patient demand.     

Immune homeostasis in the permanent inhabitants of mountain regions

Based on the study of 66 miners in the subclinical stage of manganotoxicosis the principle functional changes have been ascertained in the given condition. Revealed in the above series were an increased content of manganese in the hair of more than 3 mg% (95.5%-100.0%), the presence of neurosis-like condition presenting with elements of somatized depression, anxiety, asthenization, slight decline in the mnestic functions (69.6%-93.5%), mild impairment of the power of voluntary movement, parasympathetic type vegetative dystonia (42%-73.7%), slight changes in cerebral and peripheral hemodynamics (36.6%-68.6%), disordered bioelectrical activity of muscles of the extrapyramidal type (53.7%-83.2%), breakdown of mechanisms of adaptation of the sympathoadrenal (19.1%-49.3%) and cholinergic (26.3%-57.9%) systems.     

Von Willebrand disease: characteristics and response to desmopressin. Study of 103 cases

BACKGROUND: To describe the main characteristics and response to desmopressin infusion in 103 patients suffering from von Willebrand disease (vWD). PATIENTS AND METHODS: The criteria for diagnosis were (except for type 2N) the coexistence of von Willebrand factor ristocetin cofactor (vWF:RCo) activity < 50 U/dl with bleeding disease or one of the following data: von Willebrand factor antigen (vWF:Ag) activity < 50 U/dl, factor VIII (FVIII) activity < 50 U/dl or the existence of a increased bleeding time (BT). Multimeric studies of vWF were performed in 51 cases and ristocetin induced platelet aggregation (RIPA) was also performed. RESULTS: Spontaneous bleeding was found in 36 patients, while in 18 cases the diagnosis was done after surgical bleeding. Thirteen patients (6 presenting with mild bleeding) were studied for abnormalities in the routine preanestesic tests. Other 22 patients were diagnosed with vWD by familial studies. There were 3 patients with type 2B, 1 case with type 2N and other patient with type 3. BT was found increased in 26 out of 58 patients. The activities of vWF:CoR and vWF:Ag were 38.4 (9.4) U/dl and 45.8 (23.2) U/dl, respectively, while the activity of FVIII was 49.9 (20.8) U/dl. Prophylactic DDAVP (desmopressin) was infused in 32 patients. After 1 h, basal activities of vWF:CoR and vWF:Ag were increased by 3.1 (3.2) and 3.4 (3.1) times, respectively, and maintained for 3 h. FVIII activity increased 3.6 (2.3) times the basal levels decreasing after 3 h (2.9 [2.1]; p < 0.01). The BT was corrected in 8 out of ten patients. CONCLUSIONS: vWD is a major cause of surgical bleeding. Preanestesic anamnesis and coagulation tests can be useful to identify vWD. Many patients with vWD have normal BT. A failure in the response to desmopressin infusion is unusual.     

Computational learning reveals coiled coil-like motifs in histidine kinase linker domains

The recent rapid growth of protein sequence databases is outpacing the capacity of researchers to biochemically and structurally characterize new proteins. Accordingly, new methods for recognition of motifs and homologies in protein primary sequences may be useful in determining how these proteins might function. We have applied such a method, an iterative learning algorithm, to analyze possible coiled coil domains in histidine kinase receptors. The potential coiled coils have not yet been structurally characterized in any histidine kinase, and they appear outside previously noted kinase homology regions. The learning algorithm uses a combination of established sequence patterns in known coiled coil proteins and histidine kinase sequence data to learn to recognize efficiently this coiled coil-like motif in the histidine kinases. The common appearance of the structural motif in a functionally important part of the receptors suggests hypotheses for kinase regulation and signal transduction.     

Technical report: Initial experiences with an experimental solid-state universal digital X-ray image detector

This paper presents a brief technical evaluation and first review of clinical experiences with an experimental direct digital X-ray image detector designed to support both dynamic and snap-shot imaging. Derivatives of this type of image detector can potentially fulfil the majority of the fluoroscopic and radiographic imaging requirements of clinical radiology departments, and initial results suggest that imaging systems using the new technology will provide a high quality dose-efficient solution to the search for a universal digital X-ray image detector.     

Synergy between simulation and experiment in describing the energy landscape of protein folding

Experimental data from protein engineering studies and NMR spectroscopy have been used by theoreticians to develop algorithms for helix propensity and to benchmark computer simulations of folding pathways and energy landscapes. Molecular dynamic simulations of the unfolding of chymotrypsin inhibitor 2 (CI2) have provided detailed structural models of the transition state ensemble for unfolding/folding of the protein. We now have used the simulated transition state structures to design faster folding mutants of CI2. The models pinpoint a number of unfavorable local interactions at the carboxyl terminus of the single alpha-helix and in the protease-binding loop region of CI2. By removing these interactions or replacing them with stabilizing ones, we have increased the rate of folding of the protein up to 40-fold (tau = 0.4 ms). This correspondence, and other examples of agreement between experiment and theory in general, Phi-values and molecular dynamics simulations, in particular, suggest that significant progress has been made toward describing complete folding pathways at atomic resolution by combining experiment and simulation.     

Expression of the third component of complement, C3, in regenerating limb blastema cells of urodeles

In this study we have shown that complement component C3 is expressed in the regenerating tissue during urodele limb regeneration. C3 was expressed in the dedifferentiated regeneration blastema and in the redifferentiated limb tissues in the axolotl, Amblystoma mexicanum, and in Notophthalmus viridescens. This expression was verified by immunofluorescent staining using an Ab against axolotl C3 and by in situ hybridization with an axolotl C3 cDNA probe. In the early stages of regeneration C3 appeared to be equally present in all mesenchymal cells and in the wound epithelium, whereas in the later stages it was mainly expressed in the differentiating muscle cells. Since no expression was seen in the developing limb, it appears that the C3 expression was specific to the regeneration process. We then demonstrated by hybridization experiments that a blastema cell line of myogenic origin expresses C3. All these findings implicate C3 in the dedifferentiation process and may indicate a new role for this molecule in muscle differentiation.