Effect of high hydrostatic pressure on four genotypes of F-specific RNA bacteriophages

AIMS

The pressure responses of four genotypes of F-specific RNA bacteriophages, f2, GA, Qbeta and SP, were evaluated with respect to pressure magnitude, treatment temperature and suspending medium.

METHOD AND RESULTS

The pressure responses were studied with respect to pressure magnitude (350 to 600 MPa), treatment temperature (-10 to 50 degrees C) and suspending media. Phages f2 and GA had much higher pressure resistances than Qbeta and SP. Pressure resistances of Qbeta and SP were enhanced with increase in salt concentrations in the range of 350 to 600 MPa from -10 to 50 degrees C in PBS. Qbeta and SP had greater pressure resistances when suspended in phosphate-buffered saline (PBS) with added glucose (5%, w/w), UHT whole milk and Dulbecco's Modified Eagle's Medium plus 10% fetal bovine sera than they did in PBS. Two surfactants, sucrose laurate and monolaurin, and one chelating agent, ethylenediamine tetraacetic acid (EDTA), increased the pressure resistance of Qbeta and SP, but had modest effect on either f2 or GA.

CONCLUSIONS

Four representative F-specific RNA bacteriophages, f2 (serotype I), GA (serotype II), Qbeta (serotype III) and SP (serotype IV) showed different resistances to hydrostatic pressure in the range of 350-600 MPa.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study screened for practical surrogates of HAV for validation of commercial high hydrostatic pressure processing.

Kv2 subunits underlie slowly inactivating potassium current in rat neocortical pyramidal neurons

We determined the expression of Kv2 channel subunits in rat somatosensory and motor cortex and tested for the contributions of Kv2 subunits to slowly inactivating K+ currents in supragranular pyramidal neurons. Single cell RT-PCR showed that virtually all pyramidal cells expressed Kv2.1 mRNA and approximately 80% expressed Kv2.2 mRNA. Immunocytochemistry revealed striking differences in the distribution of Kv2.1 and Kv2.2 subunits. Kv2.1 subunits were clustered and located on somata and proximal dendrites of all pyramidal cells. Kv2.2 subunits were primarily distributed on large apical dendrites of a subset of pyramidal cells from deep layers. We used two methods for isolating currents through Kv2 channels after excluding contributions from Kv1 subunits: intracellular diffusion of Kv2.1 antibodies through the recording pipette and extracellular application of rStromatoxin-1 (ScTx). The Kv2.1 antibody specifically blocked the slowly inactivating K+ current by 25-50% (at 8 min), demonstrating that Kv2.1 subunits underlie much of this current in neocortical pyramidal neurons. ScTx (300 nM) also inhibited approximately 40% of the slowly inactivating K+ current. We observed occlusion between the actions of Kv2.1 antibody and ScTx. In addition, Kv2.1 antibody- and ScTx-sensitive currents demonstrated similar recovery from inactivation and voltage dependence and kinetics of activation and inactivation. These data indicate that both agents targeted the same channels. Considering the localization of Kv2.1 and 2.2 subunits, currents from truncated dissociated cells are probably dominated by Kv2.1 subunits. Compared with Kv2.1 currents in expression systems, the Kv2.1 current in neocortical pyramidal cells activated and inactivated at relatively negative potentials and was very sensitive to holding potential.

Functional Roles of Kv1 Channels in Neocortical Pyramidal Neurons

Pyramidal neurons from layers II/III of somatosensory and motor cortex express multiple Kv1 α-subunits and a current sensitive to block by α-dendrotoxin (α-DTX). We examined functional roles of native Kv1 channels in these cells using current-clamp recordings in brain slices and current- and voltage-clamp recordings in dissociated cells. α-DTX caused a significant negative shift in voltage threshold for action potentials (APs) and reduced rheobase. Correspondingly, a ramp-voltage protocol revealed that the α-DTX–sensitive current activated at subthreshold voltages. AP width at threshold increased with successive APs during repetitive firing. The steady-state threshold width for a given firing rate was similar in control and α-DTX, despite an initially broader AP in α-DTX. AP voltage threshold increased similarly during a train of spikes under control conditions and in the presence of α-DTX. α-DTX had no effect on input resistance or resting membrane potential and modest effects on the amplitude or width of a single AP. Accordingly, experiments using AP waveforms (APWs) as voltage protocols revealed that α-DTX–sensitive current peaked late during the AP repolarization phase. Application of α-DTX increased the rate of firing to intracellular current injection and increased gain (multiplicative effects), but did not alter spike-frequency adaptation. Consistent with these findings, voltage-clamp experiments revealed that the proportion of outward current sensitive to α-DTX was highest during the interval between two APWs, reflecting slow deactivation kinetics at −50 mV. Finally, α-DTX did not alter the selectivity of pyramidal neurons for DC versus time-varying stimuli.

Expression and biophysical properties of Kv1 channels in supragranular neocortical pyramidal neurones

Potassium channels are extremely diverse regulators of neuronal excitability. As part of an investigation into how this molecular diversity is utilized by neurones, we examined the expression and biophysical properties of native Kv1 channels in layer II/III pyramidal neurones from somatosensory and motor cortex. Single-cell RT-PCR, immunocytochemistry, and whole cell recordings with specific peptide toxins revealed that individual pyramidal cells express multiple Kv1 alpha-subunits. The most abundant subunit mRNAs were Kv1.1 > 1.2 > 1.4 > 1.3. All of these subunits were localized to somatodendritic as well as axonal cell compartments. These data suggest variability in the subunit complexion of Kv1 channels in these cells. The alpha-dendrotoxin (alpha-DTX)-sensitive current activated more rapidly and at more negative potentials than the alpha-DTX-insensitive current, was first observed at voltages near action potential threshold, and was relatively insensitive to holding potential. The alpha-DTX-sensitive current comprised about 10% of outward current at steady-state, in response to steps from -70 mV. From -50 mV, this percentage increased to approximately 20%. All cells expressed an alpha-DTX-sensitive current with slow inactivation kinetics. In some cells a transient component was also present. Deactivation kinetics were voltage dependent, such that deactivation was slow at potentials traversed by interspike intervals during repetitive firing. Because of its kinetics and voltage dependence, the alpha-DTX-sensitive current should be most important at physiological resting potentials and in response to brief stimuli. Kv1 channels should also be important at voltages near threshold and corresponding to interspike intervals.

Genetic polymorphisms of CYP3A5 genes and concentration of the cyclosporine and tacrolimus

OBJECTIVE

CYP3A is the major enzyme responsible for metabolism of the calcineurin inhibitors cyclosporine (CsA) and tacrolimus. Our objective was to determine the relationship between genetic polymorphisms of CYP3A5 with respect to interindividual variability in CsA and tacrolimus pharmacokinetics.

METHODS

Kidney transplant recipients receiving CsA (n = 137) or tacrolimus (n = 30) were genotyped for CYP3A5*3 and *6 by a PCR/RFLP method. The patients were grouped according to the CYP3A5 genotype. Dose-adjusted trough levels were correlated with the corresponding genotype.

RESULTS

At 3, 6, and 12 months, the tacrolimus dose-adjusted trough levels (dose-adjusted C0) showed a statistically significant difference between the group of CYP3A5*3/*3 (n = 19) and the group of CYP3A5*1 allele carriers. The former was higher than the latter. The CsA dose-adjusted C0 and the actual C0 did not display a significant relation (P < .05) between the group of CYP3A5*3/*3 and the group of CYP3A5*1 allele carriers.

CONCLUSION

Patients with the CYP3A5*3/*3 genotype require less tacrolimus to reach target concentrations compared to those with the CYP3A5*1 allele.

Response of four types of coliphages to high hydrostatic pressure

Pressure inactivation of four types of coliphages, varphiX 174 (ssDNA virus), MS2 (ssRNA virus), lambda imm434 (dsDNA virus) and T4 (dsDNA virus), was studied to evaluate their potential as human enteric viral surrogates for use in validation of commercial pressure processing treatments. Phage varphiX 174 demonstrated an unexpected high resistance to pressure with no more than 1-log(10) reduction observed following exposures to 350-600 MPa. There was no greater than 1-log(10) reduction below 500 MPa for MS2 in modified phosphate-buffered saline, but a 3.3-log(10) reduction was observed for MS2 pressurized at 600 MPa. Coliphages lambda imm434 and T4 were relatively sensitive to pressure in demonstrating inactivation at 350 MPa. At 21 degrees C, lambda imm434 was inactivated in modified phosphate-buffered saline or Dulbecco's Modified Eagle's Medium plus 5% fetal bovine sera by at least 7.5-log(10) when exposed to 400 MPa for 5 min. Treatment at 450 MPa for 5 min was necessary to obtain a log(10) reduction of 6-7 for T4.

Expression of CD158b on Peripheral Blood Lymphocytic Cell After Kidney Transplantation

OBJECTIVE

To investigate the expression of CD158b on peripheral blood lymphocytes after kidney transplantation.

METHODS

Sixty two kidney transplant patients were divided into two groups (normal group and rejection group) according to pathologic results and clinical situation. Blood samples were assessed for percentage of CD3+; CD19+; CD3-CD16/56+; CD3+CD158b+; CD19+CD158b+, and CD3-CD16/56+CD158b+ subsets.

RESULTS

The percentages of CD3+ cells preop as well as at 1 and 7 postoperative and the day acute rejection happened were 60.06 +/- 4.67, 40.43 +/- 4.11, 31.67 +/- 4.04, and 39.21 +/- 5.20, respectively. The percentages of CD3-CD16/56+ were 21.65 +/- 1.79, 33.84 +/- 5.45, 38.10 +/- 4.86, and 39.53 +/- 4.80, respectively. The percentages of CD3+CD158b+ were 1.46 +/- 0.31, 1.88 +/- 0.70, 2.03 +/- 1.04, and 0.65 +/- 0.12, respectively. The percentages of CD3-CD16/56+CD158b+ were 5.87 +/- 1.24, 3.57 +/- 0.57, 2.82 +/- 0.45, and 1.60 +/- 0.33, respectively.

CONCLUSIONS

The percentage of CD3+ cells in the normal and the rejection groups decreased significantly. The percentages of CD158b+T cells decreased significantly after acute rejection. The percentage of CD158b+NK cells decreased significantly after kidney transplantation, decreasing gradually after acute rejection. The percentage of CD158b+ total T cells decreased significantly following acute rejection. The percentage of CD3-CD16/56+CD158b+ of total NK cells decreased significantly after kidney transplantation and after acute rejection. Because few factors interfere with the expression of CD158b on NK cells, monitoring of this marker may be accurate and sensitive.

Thermal inactivation of Listeria innocua in salmon (Oncorhynchus keta) caviar using conventional glass and novel aluminum thermal-death-time tubes

Differences in the come-up times and thermal inactivation parameters of Listeria innocua in salmon (Oncorhynchus keta) caviar containing 2.5% salt using conventional thermal-death-time (TDT) glass tubes and a novel aluminum tube were tested and compared. Generally, the come-up times and decimal reduction times (D-values) were shorter and the change in temperature required to change the D-value (z-value) was longer in the aluminum than in the glass tubes. The D-values at 60, 63, and 65 degrees C for the aluminum TDT tubes were 2.97, 0.77, and 0.40 min, respectively, and for the glass TDT tubes, these values were 3.55, 0.84, and 0.41 min. The z-values were 5.7 degrees C in the aluminum and 5.3 degrees C in the glass. Because of the shorter come-up time, the aluminum TDT tubes may provide a more precise measurement of microbial thermal inactivation than the glass TDT tubes, particularly for viscous materials, solid foods, and foods containing particulate matter.

Relationship between the expression levels of CD61, CD63, and PAC-1 on platelet surface in peripheral blood and the transplanted kidney function

OBJECTIVE

To analyze the relationships between the expression levels of CD61, CD63, and PAC-1 on the platelet surface and the incidences of acute rejection and tubular necrosis as well as the recovery of graft function after renal transplantation.

METHODS

The expression levels of CD61, CD63, and PAC-1 on platelet surfaces were assayed by flow cytometry in 86 patients with different stages of uremia before and after transplantation. Patients were divided into three groups: 29 patients with normal graft function, 30 with acute rejection, and 27 with acute tubular necrosis. Patients with acute rejection were randomly assigned into groups treated with or without anticoagulants.

RESULTS

The expression levels of CD61, CD63, and PAC-1 on platelet surfaces significantly increased (P <.05) among patients with acute rejection, as compared with those with normal graft function or acute tubular necrosis. Compared with controls, the expression levels of CD61, CD63, and PAC-1 were lower among acute rejection patients who, received anticoagulant therapy. The recovery time for graft function shorter and, the 1-year patients and graft survival rates higher.

CONCLUSIONS

The pretransplant expression levels of CD61, CD63, and PAC-1 on platelet surface were significantly higher among patients with acute rejection, suggesting that this complication rather than acute tubular necrosis may be related to platelet activation. Patients with acute rejection displayed benefit from anticoagulant therapy.

[Land degradation and landscape ecological construction in Liaoning Province]

The degradation degree, area and distribution of three types of degraded land caused by erosion, desertification and salinization were investigated in Liaoning Province by using landsat TM 1:250,000 and GIS Data. The area of eroded, desertificated and salinized land occupied 92.5%, 3.39% and 2.22% of the total provincial land area, respectively. Therefore, the land in this province was classified into three degradation regions: contemporary erosion degradation, geological erosion degradation, and desertification and salinization degradation region. The characteristics and the cause of degradation for each region were also analyzed. According to the local situation and the theory of landscape ecology, some landscape construction and restoration models were proposed.

[Determination of DNA binding domains in hepatitis C virus core protein]

OBJECTIVE

To determine the DNA binding domain in hepatitis C virus core protein and otelucidate the significance of binding.

METHODS

Segments of hepatitis C virus core protein were expressed in E.coli as fusion forms with glutathion S-transferase (GST). The core proteins were immobilized in SDS-PAGE gel after removing SDS from the gel by washing. (32)P-ATP labeled oligonucleotides were electrophoresed through the gel in TAE buffer. The binding of DNA with core protein was detected by autoradiography.

RESULTS

There were at least two DNA binding domains in the HCV core protein, the first locating at 10~16aa and the second at 46-70aa. The second region was divided into three adjacent parts, which could bind core protein independently. Core protein bound to single strand DNA as well as to double strand DNA without sequence specificity.

CONCLUSIONS

DNA binding regions of HCV core protein locate at its N-terminus. The binding regions of HCV core protein overlap its nucleus transfer signals and they bind to target DNA unselectively, suggesting a possible mechanism for its multifunction. The result provides basic data for understanding the biological function of HCV core protein.

[Energy production of plants in grass, Dicranopteris dichotoma and Rhodomyrtus tomentosa communities in Hong Kong]

With harvest method and caloric value analysis, this paper studied the caloric values, standing energy, net fixed energy and net standing energy increment of three plant communities i.e., grass, Dicranopteris dichotoma and Rhodomyrtus tomentosa, in Hong Kong. The results showed that the caloric value was higher in D. dichotoma community and lower in grass community. The standing energy of plants in grass, D. dichotoma and R. tomentosa community was 18,638, 38,436 and 65,632 kJ.m-2; net fixed energy was 13,286, 20,354 and 18,784 kJ.m-2.yr-1; and net standing energy increment was 3437, 9626 and 6695 kJ.m-2.yr-1, respectively. Compared with southern subtropical evergreen broad-leaved forest, the standing energy, net fixed energy and net standing energy increment were lower in grass, D. dichotoma and R. tomentosa communities, which resulted from deforestation and other human disturbance. This indicated that vegetation conversion due to human disturbance would reduce the utilization coefficient of solar energy. Net fixed energy was also found to be reduced significantly with increasing intensity of human disturbance.

[Geostrophic deviation analysis of regional effects of protective forest system in reducing windspeed in north Liaoning plain]

East Asian synoptic charts and ground wind data in April and May of four counties of north Liaoning plain were selected to calculate the regional effects of protective forest system in reducing windspeed by geostrophic deviation method. The results show that the protection effects increased with increasing forestration area. Different protection effects of protective forest appeared at different daytime, with the greatest at 14:00 and smallest at 2:00, and the average windspeed reduced 13.3%. The characteristics of the geostrophic deviation method was also discussed.

[MMF and CyA in the prevention of early acute rejection after renal transplantation]

OBJECTIVE

To investigate the effect of MMF and low dose CyA on the prevention of early acute rejection after renal transplantation.

METHODS

146 patients with kidney transplantation were analyzed retrospectively from December 1997 to January 1999. These patients were divided into two groups according to the immunosuppressive regimen: Aza group (78 patients) and MMF group (68 patients). All patients met the following criteria: HLA mismatch </= 3 loci, lymphocytes toxicity test < 10%, PRA < 20% for second or third transplantation, warm ischemia time 5-11 minutes, and cold ischemia time 3-24 hours.

RESULTS

There were 24 patients with acute rejection episodes (30.77%) in the Aza group; and 10 patients (14.71%) in the MMF group, (P < 0.05). The dosage of CyA and blood concentration of CyA were significantly different; 6.00 +/- 1.21 mg x kg(-1) x d(-1) and 286.00 +/- 20.02 microg/L in the Aza group; 4.00 +/- 1.14 mg x kg(-1) x d(-1) and 204.00 +/- 20.18 microg/L in the MMF group (P < 0.001).

CONCLUSIONS

MMF with low dose CyA based triple regimen could prevent the acute rejection episodes effectively at the early period of post transplantation. This triple regimen can reduce the acute rejection episodes by 50%. To some extent, low dose CyA may avoid nephrotoxicity. The long-term effect of this regimen on allograft is still needed to observe.

[Simultaneous pancreas-kidney transplantation for the treatment of type I diabetes with end-stage renal disease]

OBJECTIVE

To demonstrate whether simultaneous pancreas-kidney transplantation is practical for the treatment of Type I diabetes with end-stage renal disease.

METHODS

Eight cases of combined pancreas-kidney transplantation were performed in our institute. The age ranged from 35 years to 48 years (average 43.46 years). All cases were diagnosed as type I diabetes with end-stage nephropathy, two cases with blindness due to retinopathy. The case history ranged from 2 years to 22 years. Pancreas allograft was placed in the right iliac fossa with pancreas exocrine drainage to bladder, whereas renal allograft the in left iliac fossa. Initial immunosuppression regimen is quadruple.

RESULTS

Seven patient could be insulin free after transplantation, with normal fasting blood glucose. One patient received insulin treatment for 40 days after operation. One patient survived 1 year and 9 months after transplantation with normal functioning pancreas allograft and kidney allograft. Four patient survived 2 months with normal allograft function. Fasting blood glucose was between 4.5 and 6.2 mmol/L; Cr was between 53 and 106 micromol/L. Diet control was not necessary. Two patient died of encephalorrhagia, and 1 pancreatic vascular thrombosis and necrotic pancreatitis.

CONCLUSIONS

Combined pancreas-kidney transplantation is feasible to treat type I diabetes with end-stage nephropathy. Functional pancreas allograft could be procured in the present condition. Pancreatic exocrine is drained to bladder. The diagnosis of acute rejection could be made earlier by detecting urine amylase. Heparin should be added in order to prevent pancreatic thrombosis.

[Wind tunnel experiment on canopy structural parameters of isolated tree and wind velocity field characters nearby]

The canopy structural parameters(porosity beta and permeability alpha) of isolated tree, and the wind velocity field character nearby were analyzed by wind tunnel experiment. The results show that alpha and beta fitted the function of alpha = beta 0.6, and the wind velocity nearby decreased in ellipsoid contour. The contour increased with increasing tree height and canopy width, and decreased with increasing permeability (or porosity). The isotach became the shape of ellipses or elliptic segments in horizontal and vertical plans.

[Landscape heterogeneity of urban vegetation in Guangzhou]

Seven indexes were used to study the landscape heterogeneity of vegetation in Guangzhou City. The results show that the patch density was 11.8 patches.km-2 and the line corridor density was 1.87 km.km-2. In old urban area, the vegetation landscape was characterized by small patches, heavy fragmentation, high diversity and random distribution, showing a highly heterogeneous spatial pattern, while in new urban area, the vegetation landscape was characterized by big patches and even distribution. Therefore, when the size of vegetation area was the same, the even distribution of vegetation could improve the landscape heterogeneity and make the ecological function more effective.

[Spectral characteristics of solar radiation in broadleaved Korean pine forest in Changbai Mountain]

Based on the measurement above and below forest canopy and meteorological data, the spectral characteristics of solar radiation in broadleaved Korean pine forest in Changbai Mountain was analyzed. The results show that the photosynthetically active radiation(PAP) coefficients of total radiation, direct radiation and scatter radiation changed daily and yearly, with an annual averages of 0.46, 0.43 and 0.56 respectively. The average reflectivity, transmissitvity and absorptivity of single leaves of different tree species in Korean pine forest were 27.0%, 23.4%, 49.6% respectively. Single leaves nearly absorbed all of the ultraviolet radiation(UV) and 71.8% of photosynthetically active radiation, but transmitted 9.6% and reflected 18.6%. As for near-infrared radiation (NIR), the reflectivity and transmissitivity of leaves were a little less than the absorptivity. The forest canopy absorbed 93.9% PAR and 94.1% UV, but reflected and transmitted less. It absorbed 59.2%, reflected 26.3% and transmitted 14.4% NIR.

[Spectrophotometric assay of polyethyene glycol in urine using ammonium ferrothiocyanate aqueous-chloroform system]

A spectrophotometric method for the quantitative determination of polyethylene glycol-600 (PEG-600) in urine is based on partitioning a chromophore present in ammonium ferrothiocyanate reagent into an aqueous phase and a chloroform phase in the presence of PEG. The method is simple and reproducible, and can detect PEG in a concentration of 0.25 g/L. It gives a linear response over a range of 0.25-2.5 g/L. The recovery of PEG-600 in urine is 107% and relative standard deviation is less than 5%.

A study of multiple biomarkers in coke oven workers--a cross-sectional study in China

We conducted a cross-sectional molecular epidemiological study of coke oven workers exposed to the established carcinogen polycyclic aromatic hydrocarbons (PAHs) to evaluate the relationships between both traditional 'exposure markers' and a series of biomarkers, including urinary 1-hydroxypyrene as a marker of internal dose, leukocyte aromatic DNA adducts as markers of biologically effective dose, serum p53 protein as a response marker and genetic polymorphisms of cytochrome P4501A1 and glutathione S-transferase MI as susceptibility markers. Twenty-five male subjects each were randomly selected from the top, middle and bottom work areas of the oven, and the control plant. They were matched for age and smoking status. The mean levels of PAH exposure, monitored by stationary and personal samplers, and of worker urinary 1-hydroxypyrene differed significantly between the top, middle and bottom of the oven and control work areas. The highest stationary and personal PAH concentrations and 1-hydroxypyrene levels were demonstrated at the top work area. Good correlations were found between the stationary PAH levels, personal PAH levels and urinary 1-hydroxypyrene levels. No positive correlations were demonstrated between aromatic DNA adduct levels and current or cumulative PAH exposure dose. In the presence of genetic polymorphisms of cytochrome P4501A1, a positive correlation was demonstrated between aromatic DNA adducts and urinary 1-hydroxypyrene levels. There was also a significant correlation between serum p53 protein levels and the cumulated benzo[a]pyrene exposure dose. Although these biomarkers have certain limitations, they are applicable to cancer epidemiology, and may contribute to our understanding of the mechanisms of carcinogenesis.

An amino-terminal fragment of LCRF, LCRF-(1-35), has the same activity as the natural peptide

A cholecystokinin (CCK)-releasing peptide, luminal CCK-releasing factor (LCRF), has been purified from rat jejunal secretion. Amino acid analysis and mass spectral analysis showed that the purified peptide is composed of 70-75 amino acid residues and has a mass of 8,136 Da. Microsequence analysis of LCRF yielded an amino acid sequence for the amino-terminal 41 residues. To determine the biologically active region of the molecule, a peptide was synthesized consisting of the amino-terminal 35 amino acids of LCRF. In this study, intraduodenal infusion of LCRF-(1-35) significantly stimulated pancreatic secretion in conscious rats. The dose-response curves to LCRF-(1-35) and to monitor peptide were similar and biphasic, with higher doses producing submaximal pancreatic secretory responses. The CCK-A receptor antagonist MK-329 abolished the pancreatic secretory response to intraduodenally infused LCRF-(1-35). These results demonstrate that LCRF biological activity is contained within the amino-terminal 35-amino acid portion of LCRF, and this fragment may be useful for investigating the role of LCRF in gastrointestinal function.