A single amino acid in the RNA-dependent RNA polymerase of Plantago asiatica mosaic virus contributes to systemic necrosis

From a lily isolate of Plantago asiatica mosaic virus (PlAMV-Li), two sub-isolates (Li1 and Li6) were obtained. Although the nucleotide sequences of Li1 and Li6 were highly conserved, they showed different pathogenicity in Nicotiana benthamiana. Li1 caused necrosis, whereas Li6 infected the plant asymptomatically. Inoculation tests with chimeric and point-mutated viruses revealed that amino acid 1154 of the RNA-dependent RNA polymerase (RdRp) contributes to the necrotic symptoms. The accumulation of the mutant viruses, in which amino acid 1154 of the RdRp was exchanged to the wild-type codon in Li1 and Li6, was almost equal.

Promotion of axonal maturation and prevention of memory loss in mice by extracts of Astragalus mongholicus

BACKGROUND AND PURPOSE

Neurons with atrophic neurites may remain alive and therefore may have the potential to regenerate even when neuronal death has occurred in some parts of the brain. This study aimed to explore effects of drugs that can facilitate the regeneration of neurites and the reconstruction of synapses even in severely damaged neurons.

EXPERIMENTAL APPROACH

We investigated the effects of extracts of Astragalus mongholicus on the cognitive defect in mice caused by injection with the amyloid peptide Abeta(25-35). We also examined the effect of the extract on the regeneration of neurites and the reconstruction of synapses in cultured neurons damaged by Abeta(25-35).

KEY RESULTS

A. mongholicus extract (1 g kg(-1) day(-1) for 15 days, p.o.) reversed Abeta(25-35)-induced memory loss and prevented the loss of axons and synapses in the cerebral cortex and hippocampus in mice. Treatment with Abeta(25-35) (10 microM) induced axonal atrophy and synaptic loss in cultured rat cortical neurons. Subsequent treatment with A. mongholicus extract (100 microg/ml) resulted in significant axonal regeneration, reconstruction of neuronal synapses, and prevention of Abeta(25-35)-induced neuronal death. Similar extracts of A. membranaceus had no effect on axonal atrophy, synaptic loss, or neuronal death. The major known components of the extracts (astragalosides I, II, and IV) reduced neurodegeneration, but the activity of the extracts did not correlate with their content of these three astragalosides.

CONCLUSION AND IMPLICATIONS

A. mongholicus is an important candidate for the treatment of memory disorders and the main active constituents may not be the known astragalosides.

Stress-relaxation and microscopic dynamics of rabbit periodontal ligament

The aim of the present study was to examine the structural basis for the stress-relaxation behaviour of the periodontal ligament (PDL). Seventeen 4-month-old rabbits were used. A tooth-PDL-bone segment was cut in a rectangular prism from the incisor of a dissected mandible. The specimen was mounted in a testing machine built on a video stereomicroscope. Following preconditioning, each specimen was stretched to a deformation of 35 microm and then the deformation was kept constant for 300 s to obtain a stress-relaxation curve. Thereafter, stress-relaxation tests were repeated sequentially at deformations of 55, 75, and 95 microm. Polarised-light video-stereomicroscopic images of the specimens were simultaneously recorded and analysed with the stress-relaxation curves. The image analysis revealed that during stress-relaxation, the brightness of the birefringent fibres tended to initially increase rapidly and then do so gradually. There were negative correlations between the brightness and relaxation modulus at the four deformations. The decreases of normalised relaxation modulus for 300 s were less at greater deformation levels. The stress-relaxation process was well described by a function with three exponential decay terms and a constant. These findings suggest that during stress-relaxation of the PDL, the alignment of the collagen molecules and fibrils within the stretched fibres may occur, which could be driven by the strain energy imparted to the specimen on initial stretching.

An approach for substrate mapping between ASM and ADM1 for sludge digestion

Kinetic modelling of the hydrolysis stage of municipal activated sludge, which is presumed to be the rate-limiting step in the anaerobic sludge digestion process, was studied by measuring methane production rate (MPR) in anaerobic batch tests. The MPR curves revealed that the degradable organic components in municipal sludge could be classified into two fractions having different kinetics. The first fraction (XS1) constituted about 55% of the sludge COD and degraded with first-order kinetics. The second fraction (XS2), which degraded during the initial phase, accounted for about 21% of sludge COD. The degradation kinetics for XS2 was expressed by Contois-type equation with respect to concentration of substrate in the fed sludge and that of active biomass in the mixture. Simultaneous batch aerobic respirometric tests showed that the activated sludge was composed of 53% heterotrophic biomass (XH-Aerobe) COD and 20% of slowly biodegradable COD (XS), that had same kinetic expressions as observed in the batch anaerobic tests. The observed correlation between substrate fractions suggests XS1 and XS2 could be directly mapped to the aerobic state variables of XH-Aerobe and Xs respectively. The degradation of XS1 seems to be anaerobic decay of XH-Aerobe while XS2 is thought to be hydrolysis of XS by microcosm of the sludge.

Nijmegen breakage syndrome and functions of the responsible protein, NBS1

Nijmegen breakage syndrome (NBS) is a rare recessive genetic disorder, characterized by bird-like facial appearance, early growth retardation, congenital microcephaly, immunodeficiency and high frequency of malignancies. NBS belongs to the so-called chromosome instability syndromes; in fact, NBS cells display spontaneous chromosomal aberrations and are hypersensitive to DNA double-strand break-inducing agents, such as ionizing radiations. NBS1, the gene underlying the disease, is located on human chromosome 8q21. The disease appears to be prevalent in the Eastern and Central European population where more than 90% of patients are homozygous for the founder mutation 657del5 leading to a truncated variant of the protein. NBS1 forms a multimeric complex with MRE11/RAD50 nuclease at the C-terminus and retains or recruits them at the vicinity of sites of DNA damage by direct binding to histone H2AX, which is phosphorylated by PI3-kinase family, such as ATM, in response to DNA damage. Thereafter, the NBS1-complex proceeds to rejoin double-strand breaks predominantly by homologous recombination repair in vertebrates. NBS cells also show to be defective in the activation of intra-S phase checkpoint. We review here some cellular and molecular aspects of NBS, which might contribute to the clinical symptoms of the disease.

New strategy of therapy for functional dyspepsia using famotidine, mosapride and amitriptyline

BACKGROUND

In functional gastrointestinal (GI) disorders including functional dyspepsia (FD) and irritable bowel syndrome (IBS), there might be no small extent of contributions of psychosomatic factors. As a therapy for IBS patients, the effectiveness of antidepressants has been reported.

AIM

In this study, we evaluated the efficacy of H2-receptor antagonist (famotidine) and 5-HT4 receptor agonist (mosapride citrate). In addition, the effect of antidepressants was assessed as the second-step therapy.

METHODS

Patients complaining upper GI symptoms were diagnosed as FD excluding organic diseases. Randomized patients received 20 mg/day of famotidine or 15 mg/day of mosapride citrate for 4 weeks and the efficacy was compared between the two groups based on a 10-point visual analogue scale. When symptoms were not relieved (score improvement 0-2 points), patients received amitriptyline (30 mg/day) or no medication for 4 weeks randomly. Patients who had depression in psychological test (SDS) were omitted.

RESULTS

As the first-step therapy, both famotidine and mosapride showed beneficial effects regardless of FD subtypes, age and gender. The efficacy of these two drugs in relieving FD symptoms was not significantly different. In patients who failed in the first-step therapy, amitriptyline showed beneficial effects.

CONCLUSIONS

These findings might be clinically important in view of the efficient relief of symptoms in FD patients.

Full-scale application of anaerobic digestion process with partial ozonation of digested sludge

For improving sludge digestion and biogas recovery, a new anaerobic digestion process combined with ozonation was tested at a full-scale unit for 2 years and its performance was compared with a simultaneously operated conventional anaerobic digestion process. The new process requires two essential modifications, which includes ozonation for enhancing the biological degradability of sludge organics and concentrating of solids in the digester through a solid/liquid separation for extension of SRT. These modifications resulted in high VSS degradation efficiency of ca. 88%, as much as 1.3 times of methane production and more than 70% reduction in dewatered sludge cake production. Owing to accumulation of inorganic solids in the digested sludge, water content of the dewatered sludge cake also reduced from 80% to 68%. An energy analysis suggested that no supplemental fuel was necessary for the subsequent incineration of the cake from the new process scheme. The process is suitable to apply to a low-loaded anaerobic digestion tank, where power production is used.

Minimization of greenhouse gas emission by application of anaerobic digestion process with biogas utilization

To assess the impact on greenhouse gas emission, different process schemes for municipal sludge treatment were evaluated based on the data from pilot-scale experiments and review of annual operation reports. A modified anaerobic digestion process with partial ozonation of digested sludge to improve biological degradability and the conventional anaerobic digestion process were compared with respect to the energy demand in each process schemes. Options for beneficial use of biogas included (1) application of biogas for power production and (2) recovery as an alternative to natural gas utilization. The analysis indicated that the partial ozonation process with power production led to minimal greenhouse gas emission because the extra energy production from this scheme was expected to cover all of the energy demand for the plant operation. Moreover, the final amount of dewatered sludge cake was only 40% of that expected from the conventional process, this significantly minimizes the potential for greenhouse gas emission in the subsequent sludge incineration processes.

Effects of alendronate on restoration of biomechanical properties of periodontium in replanted rat molars

OBJECTIVE

We examined the effect of the pretreatment of roots with alendronate on the restoration of the support function of the healing periodontal ligament in replanted rat molars.

METHODS

The left maxillary first molars were extracted, placed in 0.9% NaCl containing 1 mm alendronate (alendronate group) or 0.9% NaCl (control group) for 5 min, and were replanted into their sockets. Groups of animals were killed at 7, 14, and 21 days after replantation. Normal control rats were also killed on the same days. The force required to extract the replanted or normal tooth from its socket was measured, and a load-deformation curve was developed and analyzed. Micro-computed tomography and histologic analyses were also made.

RESULTS

The mechanical properties of the healing periodontal ligament in the alendronate group were gradually restored from 7 to 21 days. However, fractures of the roots and bones during mechanical testing occurred in most of the replanted teeth in the control group at 21 days. The rates of restoration of the mechanical strength, extensibility, stiffness, and toughness for the alendronate group at 21 days were 67, 98, 74, and 68% of the normal controls, respectively. Micro-computed tomography and histologic observations revealed that bone-like structures within the pulp and ankylosis between the roots and socket bones occurred commonly in the control group, but were uncommon in the alendronate group.

CONCLUSIONS

Our findings suggest that the pretreatment with alendronate inhibits the formation of abnormal mineralized tissues and results in better restoration of the support function of the healing periodontal ligament in replanted teeth.

Effects of age on the stress–strain and stress–relaxation properties of the rat molar periodontal ligament

OBJECTIVE

We examined the stress-strain and stress-relaxation properties of the periodontal ligament (PDL) in the rat molar at 2, 6, 12, and 24 months of age to elucidate age-related changes in the tooth support function of the PDL.

DESIGN

From the dissected left and right mandibles in each rat, a pair of transverse sections (ca. 0.45 mm in thickness) of the first molar was cut at the middle part of the mesial root. We then obtained a load-deformation curve for the PDL, using one of the paired sections. The other section was loaded to as much as 50% of the maximum load as determined from the contralateral section, and keeping the deformation constant for 10 min, a load-relaxation curve was obtained and analysed.

RESULTS

The maximum shear stress and tangent modulus decreased between 2 and 24 months of age. As the maximum shear strain increased with age (P < 0.001), the failure strain energy density did not change between 2 and 24 months of age. The stress-relaxation during the 10 min period decreased from 2 to 24 months of age (P < 0.01). The relaxation process of the PDL in each age was well described by a sum of three exponential decay functions. The age-related decrease in the relaxation was found to be mainly due to the increase in the relaxation time for the long-term relaxation component.

CONCLUSION

These results indicate that the maximum shear stress and stiffness of the rat molar PDL decrease between 2 and 24 months of age; but its toughness remains unchanged due to an increase in the extensibility. Our findings further indicate that the fluid flow and movements of macromolecules within the stretched PDL fibres during the stress-relaxation decrease with advancing age.

Relationship between the tooth eruption and regional blood flow in angiotensin II-induced hypertensive rats

OBJECTIVE

The mechanism of action of vasoactive drugs on tooth movement is unknown. The purpose of the present study was to measure simultaneously the axial movement of the mandibular incisor, regional blood flow at the base of the incisor, and systemic arterial blood pressure in angiotensin II-induced hypertensive rats to determine the possible cause of tooth displacement.

DESIGN

The measurements were made under artificial respiration with halothane anaesthesia. In the experimental animals, 2.5 microg of angiotensin II in 1 ml of Ringer's solution was infused at 0.83 ml/h for 12 h from the femoral vein. In the control animals, only Ringer's solution was infused.

RESULTS

Angiotensin II caused an increase of the mean arterial blood pressure from 86 to 119 mm Hg, and decreases of the eruption rate from 667 to 494 microm/24 h and the regional blood flow from 262 to 214 mV. There was a positive correlation between the eruption rate and regional blood flow, and a negative correlation between the blood pressure and regional blood flow.

CONCLUSION

These results suggest that angiotensin II caused constriction of the peripheral vascular smooth muscle resulting in an increase of arterial blood pressure and a decrease of regional blood flow, followed by a decrease of fluid volume and then a reduction of either the pressure within the socket or of the eruptive force. We assume that the regional vascular pressure within the socket plays an important role in determining the position of the rat incisor.

Age-related and regional differences in the stress–strain and stress–relaxation behaviours of the rat incisor periodontal ligament

Groups of rats were killed at 2, 6, 12, and 24 months of age. From dissected left and right mandibles in each rat, three pairs of transverse sections were cut at the incisal, middle, and basal regions of the incisor. One section in each pair was loaded until failure and a stress-strain curve for the periodontal ligament (PDL) was obtained. The other section was loaded to up to 50% of the maximum shear stress as determined from the contralateral section and then kept at a constant strain for 10 min, to obtain the stress-relaxation curve at the same region of the PDL. The maximum shear stress and toughness increased with age at the incisal region and the maximum shear strain increased with age at the incisal and middle regions. The tangent modulus decreased with advancing age at the middle region. The stress-relaxation during 10 min decreased with advancing age at the incisal and basal regions, but not at the middle region. The relaxation process was well described by a sum of three exponential decay functions, reflecting the short-, medium-, and long-term relaxation components. The age-related decrease in the relaxation was mainly attributable to increases in the ratio and relaxation time of the long-term relaxation component. These results suggest that with advancing age the mechanical strength and toughness of the PDL are enhanced mostly at the incisal region and that the viscous fraction is relatively decreased at the incisal and basal regions along the long axis of the rat incisor.

Process performance and change in sludge characteristics during anaerobic digestion of sewage sludge with ozonation

A new process configuration combining anaerobic digestion with ozonation, and operated at long SRT, was studied with the objective of on-site reduction in sludge quantity and improving biogas recovery. The process performance with respect to solid reduction efficiency and other important process parameters like accumulation of inorganic solids, changes in sludge viscosity and dewatering characteristics were evaluated from the data of long term pilot scale continuous experiments conducted using a mixture of primary and secondary municipal sewage sludge. Due to sludge ozonation and long SRT, high VSS degradation efficiency of approximately 80% was achieved at a reactor solid concentration of 6.5%. A high fraction of inorganic solid (>50%) consisting mainly of acid insoluble and iron compounds was found to accumulate in the reactor. The high inorganic content accumulated in the digested sludge did not, however, contribute to the observed increase in sludge viscosity at high solid concentration. The sludge viscosity was largely found to depend on the organic solid concentration rather than the total solid content. Moreover, higher inorganic content in the digested sludge resulted in better sludge dewaterability. For a quick assessment of the economic feasibility of the new process, an economic index based on the unit cost of digested sludge disposal to unit electric cost is proposed.

Effects of hydrocortisone and beta-aminopropionitrile on stress-strain and stress-relaxation behaviors, and birefringent retardation of collagen fibers in the rat incisor periodontal ligament

Three groups of male Wistar rats received daily subcutaneous injections of 10 mg/kg of hydrocortisone (HC group), 300 mg/kg of beta-aminopropionitrile (BAPN group), or saline (control group), for 10 days. The shear stress-strain and stress-relaxation properties of the incisor periodontal ligament were examined in transverse sections from dissected mandibles. Both the maximum shear stress and failure strain energy density increased significantly following the administration of hydrocortisone. The maximum shear stress decreased following the administration of BAPN. However, the stress-relaxations in the initial 10 min did not show significant differences among the three groups. Polarized light microscopic analysis revealed that the retardation value of the collagen fibers was highest in the HC group and lowest in the BAPN group for the bone-related area, but not for the tooth-related and middle areas of the ligament. It is suggested that the changes induced by hydrocortisone or BAPN occurred mainly in the elastic components and to a minor extent in the viscous components although the physical and biomechanical properties are determined by the interaction of all the various components. We also suggest that the main response to the drugs occurred in the collagen fibers in the bone-related area of the ligament.

[Utility of the perfusion-assist for beating heart coronary artery bypass surgery]

During off-pump coronary artery bypass surgery, concern remains about the possible myocardial injury associated with the transient occlusion and stabilization of the target vessels. To try to minimize myocardial ischemia and achieve hemodynamic stability, we utilized a coronary perfusion catheter combined with the perfusion-assisted direct coronary artery bypass system that enables active and modified coronary perfusion of the target vessel throughout the duration of multiple grafting (modified PADCAB). In the series of 10 patients, perfusion of the target coronary systems averaged 2,072.8 +/- 649.7 ml over 92.9 +/- 26.1 minutes under a constant infusion pressure of 120 mmHg. Nitroglycerin (100 micrograms/l of flow) was delivered directly into the coronary arteries as an additive in all patients. Hemodynamic instability was notably absent in all cases, even in cases that required difficult anastomosis with a relatively long time for the anastomosis. There were no perioperative complications and no detectable myocardial damage (i.e., impairment of myocardial wall motion indicated by echocardiography findings or by > 0.25 ng/ml of troponin-T release compared to the preoperative level) in this series of patients.

The effects of intrusive loading on axial movements of impeded and unimpeded rat incisors: estimation of eruptive force

Axial movements of impeded and unimpeded rat mandibular incisors were measured following application and removal of intrusive loads of 1, 2, 5, 10 and 20 mN in a stepwise order at intervals of 1h on erupting teeth. The tooth movements were recorded by a displacement detector under artificial respiration with halothane anaesthesia. The loading and unloading procedures brought about the tooth movements in two steps: an initial rapid movement immediately after application or removal of the load and a subsequent slow and gradual movement. The initial rapid intrusive or extrusive tooth movements were significantly greater in the unimpeded than in the impeded teeth at the same load. The forces to stop extrusive tooth movements, estimated from the formula of regression lines showing correlations between the intrusive loads from 0 to 5 mN and tooth movements (microm/30 min), were 4.2 mN in the impeded and 2.9 mN in the unimpeded incisors. We suggest that repeated shortenings of the rat incisor did not cause an increase in the eruptive force and that changes in the resistance of the periodontal ligament predominantly regulate the axial movement of the rat incisor.

Detection of cerebral hypoperfusion with bispectral index during paediatric cardiac surgery

BACKGROUND

The bispectral index (BIS) may indicate changes in cerebral activity when the cerebral circulation is affected by acute hypotension.

METHODS

We measured BIS and cerebral haemoglobin saturation (Sr(O(2))) by near-infrared spectroscopy in 10 children undergoing cardiac surgery.

RESULTS

We noted 14 episodes of simultaneous decreases in Sr(O(2)) and BIS during acute hypotension in five children. An acute decrease in BIS, which coincided with a decrease in Sr(O(2)) suggesting a reduction in cerebral blood flow, was associated with acute slowing of the raw EEG waveforms.

CONCLUSIONS

Our findings suggest that an acute decrease in BIS during acute hypotension indicates cerebral hypoperfusion, and that cerebral hypoperfusion caused by hypotension may occur frequently during paediatric cardiac surgery.