[Advances in the diagnosis and treatment strategy of polymyxin resistant Klebsiella pneumoniae]

In recent years, the detection rate of multidrug-resistant and pandrug-resistant Klebsiella pneumoniae has increased year on year, so polymyxin has received increasing attention as an antibiotic that is still sensitive to most of the multidrug-resistant strains. However, widespread use of polymyxin is likely to lead to the emergence of polymyxin-resistant Klebsiella pneumoniae. At the same time, the polymyxin hetero-resistance has made clinical prevention and treatment difficult. In addition to relying on the combination of polymyxins with other antibiotics, the search for new antibacterial drugs has also become a research hotspot. Research into early detection methods for polymyxin resistance can also help to optimize and improve the diagnosis and treatment strategies. This article reviewed the epidemic status, mechanism, detection methods and prevention measures of polymyxin-resistant Klebsiella pneumoniae.

[Management strategy of femoral artery pseudoaneurysm combined with infectious wounds]

Objective: To investigate the surgical treatment methods of femoral artery pseudoaneurysm combined with infectious wounds and to evaluate the clinical effects. Methods: The retrospective observational research method was used. Twelve patients with femoral artery pseudoaneurysm combined with infectious wounds who met the inclusion criteria were admitted to Nanjing University of Chinese Medicine Wuxi Integrated Traditional Chinese and Western Medicine Hospital (Affiliated Hospital of Jiangnan University) from October 2014 to September 2022, including 6 males and 6 females, aged from 46 to 78 years. In the primary operation, debridement, tumor resection, and artery suture/venous grafting to repair the artery/artery ligation were performed, and the wound area after tumor resection ranged from 4.0 cm×1.5 cm to 12.0 cm×6.5 cm. Wounds that could be sutured were treated with tension reduction suture and extracutaneous continuous vacuum sealing drainage (VSD), while large wounds that could not be sutured were treated with VSD to control infection. In the secondary operation, tension reduction suture was performed to repair the wounds that could be sutured; large wounds were repaired with adjacent translocated flaps with area of 9.0 cm×5.0 cm to 15.0 cm×7.0 cm. Additionally, when the length of the exposed femoral artery was equal to or over 3.0 cm, the wounds were repaired with additional rectus femoris muscle flap with length of 15.0 to 18.0 cm. The donor areas of the flaps were directly sutured. The wound with artery ligation was treated with stamp skin grafting and continuous VSD. The bacterial culture results of the wound exudate samples on admission were recorded. The intraoperative blood loss, the location of femoral artery rupture, the artery treatment method, and the wound repair method in the primary operation were recorded, and the durations of catheter lavage, catheter drainage, and VSD treatment, and the drainage volume after the operation were recorded. The repair method of wounds in the secondary operation, the durations of catheter drainage and VSD treatment, and the total drainage volume after the operation were recorded. The survivals of flap/muscle flap/stamp skin grafts were observed, and the wound healing time was recorded. Follow-up after discharge was performed to evaluate the quality of wound healing and the walking function and to check whether the pulsatile mass disappeared. B-ultrasound or computed tomography angiography (CTA) was performed again to observe potential pseudoaneurysm recurrence and evaluate the patency of blood flow of the femoral artery. Results: The bacterial culture results of wound exudate samples of all the patients were positive on admission. The blood loss was 150 to 750 mL in the primary operation. The arterial ruptures were located in the femoral artery in 8 cases, in the external iliac artery in 2 cases, and in the femoral arteriovenous fistula in 2 cases. Six cases received direct artery suture, 4 cases received autologous great saphenous vein grafting to repair the artery, 1 case received autologous great saphenous vein bypass surgery, and 1 case received artery ligation. The primary wound suture was performed in 4 cases, along with catheter lavage for 3 to 5 days, catheter drainage for 4 to 6 days, VSD treatment for 5 to 7 days, and a total drainage volume of 80 to 450 mL after the surgery. In the secondary operation, the wounds were sutured directly in 3 cases along with catheter drainage for 2 to 3 days, the wound was repaired with scalp stamp skin graft and VSD treatment for 5 days in 1 case, the wounds were repaired with adjacent translocated flaps in 2 cases with catheter drainage for 2 to 3 days, and the wounds were repaired with rectus femoris muscle flaps+adjacent translocated flaps in 2 cases with catheter drainage for 3 to 5 days . The total drainage volume after the secondary operation ranged from 150 to 400 mL. All the skin flaps/muscle flaps/skin grafts survived after operation. The wound healing time ranged from 15 to 36 days after the primary operation. Follow-up of 2 to 8 months after discharge showed that the wounds of all patients healed well. One patient who underwent femoral artery ligation had calf amputation due to foot ischemic necrosis, and the rest of the patients regained normal walking ability. The pulsatile mass disappeared in inguinal region of all patients. B-ultrasound or CTA re-examination in 6 patients showed that the blood flow of femoral artery had good patency, and there was no pseudoaneurysm recurrence. Conclusions: Early debridement, tumor resection, and individualized artery treatment should be performed in patients with femoral artery pseudoaneurysm combined with infected wounds. Besides, proper drainage and personalized repair strategy should be conducted according to the wound condition to achieve a good outcome.

[The effect of maternal HBV DNA levels on HBV intrauterine transmission and fetal distress]

Aim: To identify the key risk factors of intrauterine hepatitis B virus transmission (HBV) and its effect on the placenta and fetus. Methods: 425 infants born to hepatitis B surface antigen (HBsAg)-positive pregnant women who received combined immunization with hepatitis B immunoglobulin and hepatitis B vaccine between 2009 to 2015 were prospectively enrolled in this study. The intrauterine transmission situation was assessed by dynamic monitoring of infants HBV DNA load and quantitative HBsAg. Univariate and multivariate regression analysis was used to determine the high risk factors for intrauterine transmission. Stratified analysis was used to determine the relationship between maternal HBV DNA load and fetal distress. Transmission electron microscopy was used to observe HBV Effects on placental tissue. Results: HBV intrauterine infection rate was 2.6% (11/425). Multivariate analysis result showed that the maternal HBV DNA load was an independent risk factor for intrauterine infection among infants (P=0.011). Intrauterine infection and distress rate was significantly higher in infants with with maternal HBV DNA>10⁶ IU/ml than those with HBV DNA <10⁶ IU/ml (12.2% vs. 1.8%; χ²=11.275, P=0.006), and (24.4% vs. 16.0%, χ²=3.993, P=0.046). Transmission electron microscopy showed that mitochondrial edema, endoplasmic reticulum expansion and thicker basement membrane were apparent when the maternal HBV DNA>10⁶ IU/ml than that of maternal HBV DNA<10⁶ IU/ml (960 nm vs. 214 nm, Z=-2.782, P=0.005) in the placental tissue. Conclusion: Maternal HBV DNA>10⁶ IU/ml is associated not only with intrauterine infection, but also with increased incidence of intrauterine distress and placental sub-microstructural changes, providing strong clinical and histological evidence for pregnancy avoidance and treatment in this population.

[Effects of application of citrate anticoagulation in bedside continuous blood purification of severe burn patients with sepsis]

Objective: To investigate the effects of application of citrate anticoagulation in bedside continuous blood purification (CBP) of severe burn patients with sepsis, so as to provide reference for choosing anticoagulants in CBP of these patients. Methods: Thirty severe burn patients with sepsis, conforming to the study criteria, were admitted to our burn intensive care unit from January 2014 to July 2017. Patients were divided into heparin group and citrate group according to computer randomization method, with 15 cases in each group. Patients in two groups all received bedside CBP treatment. Patients in heparin group used local heparin anticoagulation, while patients in citrate group used local citrate anticoagulation. Time of predicted single-time CBP treatment, time of single-time CBP treatment, time of accumulative CBP treatment, and rate of reaching the standard of CBP treatment time were counted. Changes of prothrombin time (PT), activated partial thromboplastin time (APTT), international normalized ratio (INR), fibrinogen, serum procalcitonin, and C-reactive protein (CRP) of patients before and after treatment were monitored. Hemorrhage in wounds, incision on trachea, and arteriovenous intubation point, and other complications during and after CBP treatment were observed. Data were processed with independent sample t test and chi-square test. Results: (1) Time of predicted single-time CBP treatment of patients in the two groups was equal. Time of single-time CBP treatment and time of accumulative CBP treatment of patients in citrate group were longer than those in heparin group. Rate of reaching the standard of CBP treatment time of patients in citrate group was significantly higher than that in heparin group (χ(2)=16.655, P<0.01). (2) There was no statistically significant difference in PT, APTT, INR, fibrinogen, serum procalcitonin, and CRP of patients in the two groups before CBP treatment (t=0.203, -1.006, 0.203, 0.039, -1.591, -0.824, P>0.05). PT and APTT of patients in citrate group after CBP treatment were (14.2±1.6) and (45±7) s, respectively, significantly shorter than (15.5±1.4) and (53±6) s in heparin group (t=2.395, 3.321, P<0.05 or P<0.01). INR of patients in citrate group after CBP treatment was 1.13±0.12, significantly lower than 1.24±0.12 in heparin group (t=2.395, P<0.05). Fibrinogen of patients in citrate group after CBP treatment was (3.5±0.6) g/L, significantly higher than (3.0±0.6) g/L in heparin group (t=-2.427, P<0.05). Serum procalcitonin and CRP of patients in citrate group after CBP treatment were significantly lower than those in heparin group (t=2.520, 2.710, P<0.05). Decreased degree of serum procalcitonin and CRP of patients in citrate group after CBP treatment were (1.8±0.6) ng/mL and (143±69) mg/L, respectively, significantly higher than (0.9±0.6) ng/mL and (95±50) mg/L in heparin group (t=-4.033, -2.170, P<0.05 or P<0.01). (3) During CBP treatment, patients in heparin group experienced 21 times of exacerbation of wound hemorrhage and 10 times of new hemorrhage, including 2 times of hemorrhage at incision on trachea and 8 times of hemorrhage at arteriovenous intubation point. No exacerbation of hemorrhage or new hemorrhage happened in patients of citrate group. After CBP treatment, no electrolyte disturbance happened in patients of heparin group, but 1 patient in citrate group experienced hypocalcemia. Conclusions: Application of citrate anticoagulation in bedside CBP of severe burn patients with sepsis shows light impact on systematic coagulation status, and can effectively decrease inflammation reaction of burn sepsis with low rate of hemorrhage.

Modelling of organic matter dynamics during the composting process

Composting urban organic wastes enables the recycling of their organic fraction in agriculture. The objective of this new composting model was to gain a clearer understanding of the dynamics of organic fractions during composting and to predict the final quality of composts. Organic matter was split into different compartments according to its degradability. The nature and size of these compartments were studied using a biochemical fractionation method. The evolution of each compartment and the microbial biomass were simulated, as was the total organic carbon loss corresponding to organic carbon mineralisation into CO(2). Twelve composting experiments from different feedstocks were used to calibrate and validate our model. We obtained a unique set of estimated parameters. Good agreement was achieved between the simulated and experimental results that described the evolution of different organic fractions, with the exception of some compost because of a poor simulation of the cellulosic and soluble pools. The degradation rate of the cellulosic fraction appeared to be highly variable and dependent on the origin of the feedstocks. The initial soluble fraction could contain some degradable and recalcitrant elements that are not easily accessible experimentally.

Differential characteristics of the early stage of lung inflammation induced by SARS-CoV Nucleocapsid protein related to age in the mouse

Objective:

Severe acute respiratory syndrome (SARS) is an acute infectious disease of the respiratory system which has newly emerged. Interestingly, it appears to be a disease that predominantly affects adults while the mortality in children is extremely low. However, the pathogenesis of SARS in relation to different characteristics relevant to age remains unclear.

Material and Methods:

To better understand the role of cytokines in the immunopathological processes of SARS, weanling (4 weeks old), young (6 weeks old) and adult (10 weeks old) male BALB/C mice were inoculated intranasally with N-protein of SARS-CoV in this study. Serum or lung homogenate levels of some cytokines such as tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) along with acute injury lung index and histology were also analyzed.

Results:

Histopathological analysis of adult male BALB/C mice after N-protein infection showed progressive inflammatory reactions, especially pulmonary edema, in accordance with a moderately (~13%) elevated level of W/D ratio at 24 h. Although adult groups underwent a progressive lung inflammation in the acute phase accompanied by raised levels of TNF-α in serum, no significant changes in lung TNF-α level were reported simultaneously. Moreover, adult SARS infected BALB/c mice showed elevated levels of IFN-γ while IFN-γ levels in weanling and young groups had no obvious association with lung inflammation.

Conclusion:

Our study supports the observation that adult mice do have progressively greater immune reactions than weanling and adolescent ones over time. The relative immaturity of the immune system in weanlings may confer benefit leading to less impairment of lung function. However, the measurement of TNF-α and IFN-γ levels was not indicative of the severity of lung injury at the early stage of disease.

Speciation and distribution of arsenic and localization of nutrients in rice grains

Arsenic (As) contamination of rice grains and the generally low concentration of micronutrients in rice have been recognized as a major concern for human health. Here, we investigated the speciation and localization of As and the distribution of (micro)nutrients in rice grains because these are key factors controlling bioavailability of nutrients and contaminants. Bulk total and speciation analyses using high-pressure liquid chromatography (HPLC)-inductively coupled plasma mass spectrometry (ICP-MS) and X-ray absorption near-edge spectroscopy (XANES) was complemented by spatially resolved microspectroscopic techniques (micro-XANES, micro-X-ray fluorescence (micro-XRF) and particle induced X-ray emission (PIXE)) to investigate both speciation and distribution of As and localization of nutrients in situ. The distribution of As and micronutrients varied between the various parts of the grains (husk, bran and endosperm) and was characterized by element-specific distribution patterns. The speciation of As in bran and endosperm was dominated by As(III)-thiol complexes. The results indicate that the translocation from the maternal to filial tissues may be a bottleneck for As accumulation in the grain. Strong similarities between the distribution of iron (Fe), manganese (Mn) and phosphorus (P) and between zinc (Zn) and sulphur (S) may be indicative of complexation mechanisms in rice grains.

Speciation and distribution of arsenic and localization of nutrients in rice grains

Arsenic (As) contamination of rice grains and the generally low concentration of micronutrients in rice have been recognized as a major concern for human health. Here, we investigated the speciation and localization of As and the distribution of (micro)nutrients in rice grains because these are key factors controlling bioavailability of nutrients and contaminants. Bulk total and speciation analyses using high-pressure liquid chromatography (HPLC)-inductively coupled plasma mass spectrometry (ICP-MS) and X-ray absorption near-edge spectroscopy (XANES) was complemented by spatially resolved microspectroscopic techniques (micro-XANES, micro-X-ray fluorescence (micro-XRF) and particle induced X-ray emission (PIXE)) to investigate both speciation and distribution of As and localization of nutrients in situ. The distribution of As and micronutrients varied between the various parts of the grains (husk, bran and endosperm) and was characterized by element-specific distribution patterns. The speciation of As in bran and endosperm was dominated by As(III)-thiol complexes. The results indicate that the translocation from the maternal to filial tissues may be a bottleneck for As accumulation in the grain. Strong similarities between the distribution of iron (Fe), manganese (Mn) and phosphorus (P) and between zinc (Zn) and sulphur (S) may be indicative of complexation mechanisms in rice grains.

High percentage inorganic arsenic content of mining impacted and nonimpacted Chinese rice

Two approaches were undertaken to characterize the arsenic (As) content of Chinese rice. First, a national market basket survey (n = 240) was conducted in provincial capitals, sourcing grain from China's premier rice production areas. Second, to reflect rural diets, paddy rice (n = 195) directly from farmers fields were collected from three regions in Hunan, a key rice producing province located in southern China. Two of the sites were within mining and smeltery districts, and the third was devoid of large-scale metal processing industries. Arsenic levels were determined in all the samples while a subset (n = 33) were characterized for As species, using a new simple and rapid extraction method suitable for use with Hamilton PRP-X100 anion exchange columns and HPLC-ICP-MS. The vast majority (85%) of the market rice grains possessed total As levels < 150 ng g(-1). The rice collected from mine-impacted regions, however, were found to be highly enriched in As, reaching concentrations of up to 624 ng g(-1). Inorganic As (As(i)) was the predominant species detected in all of the speciated grain, with As(i) levels in some samples exceeding 300 ng g(-1). The As(i) concentration in polished and unpolished Chinese rice was successfully predicted from total As levels. The mean baseline concentrations for As(i) in Chinese market rice based on this survey were estimated to be 96 ng g(-1) while levels in mine-impacted areas were higher with ca. 50% of the rice in one region predicted to fail the national standard.

Health risks of heavy metals in contaminated soils and food crops irrigated with wastewater in Beijing, China

Consumption of food crops contaminated with heavy metals is a major food chain route for human exposure. We studied the health risks of heavy metals in contaminated food crops irrigated with wastewater. Results indicate that there is a substantial buildup of heavy metals in wastewater-irrigated soils, collected from Beijing, China. Heavy metal concentrations in plants grown in wastewater-irrigated soils were significantly higher (P<or=0.001) than in plants grown in the reference soil, and exceeded the permissible limits set by the State Environmental Protection Administration (SEPA) in China and the World Health Organization (WHO). Furthermore, this study highlights that both adults and children consuming food crops grown in wastewater-irrigated soils ingest significant amount of the metals studied. However, health risk index values of less than 1 indicate a relative absence of health risks associated with the ingestion of contaminated vegetables.

Highly efficient xylem transport of arsenite in the arsenic hyperaccumulator Pteris vittata

The hyperaccumulator Pteris vittata translocates arsenic (As) from roots to fronds efficiently, but the form of As translocated in xylem and the main location of arsenate reduction have not been resolved. Here, P. vittata was exposed to 5 microM arsenate or arsenite for 1-24 h, with or without 100 microM phosphate. Arsenic speciation was determined in xylem sap, roots, fronds and nutrient solutions by high-performance liquid chromatography (HPLC) linked to inductively coupled plasma mass spectrometry (ICP-MS). The xylem sap As concentration was 18-73 times that in the nutrient solution. In both arsenate- and arsenite-treated plants, arsenite was the predominant species in the xylem sap, accounting for 93-98% of the total As. A portion of arsenate taken up by roots (30-40% of root As) was reduced to arsenite rapidly. The majority (c. 80%) of As in fronds was arsenite. Phosphate inhibited arsenate uptake, but not As translocation. More As was translocated to fronds in the arsenite-treated than in the arsenate-treated plants. There was little arsenite efflux from roots to the external solution. Roots are the main location of arsenate reduction in P. vittata. Arsenite is highly mobile in xylem transport, possibly because of efficient xylem loading, little complexation with thiols in roots, and little efflux to the external medium.

Role of salicylic acid in alleviating oxidative damage in rice roots (Oryza sativa) subjected to cadmium stress

Time-dependent changes in enzymatic and non-enzymatic antioxidants, and lipid peroxidation were investigated in roots of rice (Oryza sativa) grown hydroponically with Cd, with or without pretreatment of salicylic acid (SA). Exposure to 50 microM Cd significantly decreased root growth, and activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), but increased the concentrations of H(2)O(2), malondialdehyde (MDA), ascorbic acid (AsA), glutathione (GSH) and non-protein thiols (NPT). However, pretreatment with 10 microM SA enhanced the activities of antioxidant enzymes and the concentrations of non-enzymatic antioxidants, but lowered the concentrations of H(2)O(2) and MDA in the Cd-stressed rice compared with the Cd treatment alone. Pretreatment with SA alleviated the Cd-induced inhibition of root growth. The results showed that pretreatment with SA enhanced the antioxidant defense activities in Cd-stressed rice, thus alleviating Cd-induced oxidative damage and enhancing Cd tolerance. The possible mechanism of SA-induced H(2)O(2) signaling in mediating Cd tolerance was discussed.

Uptake of oxytetracycline and its phytotoxicity to alfalfa (Medicago sativa L.)

A series of experiments were conducted in a hydroponic system to investigate the uptake of oxytetracycline (OTC) and its toxicity to alfalfa (Medicago sativa L.). OTC inhibited alfalfa shoot and root growth by up to 61% and 85%, respectively. The kinetics of OTC uptake could be well described by Michaelis-Menten equation with Vmax of 2.25 micromol g-1 fresh weight h-1, and Km of 0.036 mM. The uptake of OTC by alfalfa was strongly inhibited by the metabolic inhibitor, 2,4-DNP (2,4-dinitrophenol), at pH 3.5 and 6.0, but not by the aquaporin competitors, glycerol and Ag+. OTC uptake, however, was significantly inhibited by Hg2+, suggesting that the inhibition of influx was due to general cellular stress rather than the specific action of Hg2+ on aquaporins. Results from the present study suggested that OTC uptake into alfalfa is an energy-dependent process.

Arsenic sequestration in iron plaque, its accumulation and speciation in mature rice plants (Oryza sativa L.)

A compartmented soil-glass bead culture system was used to investigate characteristics of iron plaque and arsenic accumulation and speciation in mature rice plants with different capacities of forming iron plaque on their roots. X-ray absorption near-edge structure spectra and extended X-ray absorption fine structure were utilized to identify the mineralogical characteristics of iron plaque and arsenic sequestration in plaque on the rice roots. Iron plaque was dominated by (oxyhydr)oxides, which were composed of ferrihydrite (81-100%), with a minor amount of goethite (19%) fitted in one of the samples. Sequential extraction and XANES data showed that arsenic in iron plaque was sequestered mainly with amorphous and crystalline iron (oxyhydr)oxides, and that arsenate was the predominant species. There was significant variation in iron plaque formation between genotypes, and the distribution of arsenic in different components of mature rice plants followed the following order: iron plaque > root > straw > husk > grain for all genotypes. Arsenic accumulation in grain differed significantly among genotypes. Inorganic arsenic and dimethylarsinic acid (DMA) were the main arsenic species in rice grain for six genotypes, and there were large genotypic differences in levels of DMA and inorganic arsenic in grain.

Arsenic sequestration in iron plaque, its accumulation and speciation in mature rice plants (Oryza sativa L.)

A compartmented soil-glass bead culture system was used to investigate characteristics of iron plaque and arsenic accumulation and speciation in mature rice plants with different capacities of forming iron plaque on their roots. X-ray absorption near-edge structure spectra and extended X-ray absorption fine structure were utilized to identify the mineralogical characteristics of iron plaque and arsenic sequestration in plaque on the rice roots. Iron plaque was dominated by (oxyhydr)oxides, which were composed of ferrihydrite (81-100%), with a minor amount of goethite (19%) fitted in one of the samples. Sequential extraction and XANES data showed that arsenic in iron plaque was sequestered mainly with amorphous and crystalline iron (oxyhydr)oxides, and that arsenate was the predominant species. There was significant variation in iron plaque formation between genotypes, and the distribution of arsenic in different components of mature rice plants followed the following order: iron plaque > root > straw > husk > grain for all genotypes. Arsenic accumulation in grain differed significantly among genotypes. Inorganic arsenic and dimethylarsinic acid (DMA) were the main arsenic species in rice grain for six genotypes, and there were large genotypic differences in levels of DMA and inorganic arsenic in grain.

Increase in rice grain arsenic for regions of Bangladesh irrigating paddies with elevated arsenic in groundwaters

Concern has been raised by Bangladeshi and international scientists about elevated levels of arsenic in Bengali food, particularly in rice grain. This is the first inclusive food market-basket survey from Bangladesh, which addresses the speciation and concentration of arsenic in rice, vegetables, pulses, and spices. Three hundred thirty aman and boro rice, 94 vegetables, and 50 pulse and spice samples were analyzed for total arsenic, using inductivity coupled plasma mass spectrometry (ICP-MS). The districts with the highest mean arsenic rice grain levels were all from southwestern Bangladesh: Faridpur (boro) 0.51 > Satkhira (boro) 0.38 > Satkhira (aman) 0.36 > Chuadanga (boro) 0.32 > Meherpur (boro) 0.29 microg As g(-1). The vast majority of food ingested arsenic in Bangladesh diets was found to be inorganic; with the predominant species detected in Bangladesh rice being arsenite (AsIII) or arsenate (AsV) with dimethyl arsinic acid (DMAV) being a minor component. Vegetables, pulses, and spices are less important to total arsenic intake than water and rice. Predicted inorganic arsenic intake from rice is modeled with the equivalent intake from drinking water for a typical Bangladesh diet. Daily consumption of rice with a total arsenic level of 0.08 microg As g(-1) would be equivalent to a drinking water arsenic level of 10 microg L(-1).

The effect of grain size of rock phosphate amendment on metal immobilization in contaminated soils

When rock phosphates (RP) are used to remediate Pb-contaminated soils, their effectiveness is likely affected by their grain size. In this study, the effect of grain size of rock phosphate on the effectiveness of heavy metal immobilization in two contaminated soils was measured in pot experiment. Rock phosphate was used with four different grain sizes: <35, 35-72, 72-133 and 133-266microm. The application rate of rock phosphate in two soils was determined based on P/metals (Pb, Zn, Cu and Cd) molar ratio of 5.0 in the soils. The results showed that rock phosphate of the smallest grain size (<35microm) was superior to all of other grain sizes more than 35microm for reducing uptake in plant (Brassica oleracea L.) shoots for Cd (19.6-50.0%), Pb (21.9-51.4%) and Zn (22.4-34.6%), respectively, as compared with the soil without application of rock phosphate. Sequential extraction analysis indicated that rock phosphate was most effective for soil Pb to induced transformation from non-residual fractions to a residual fraction than that for Zn and Cd. Such transformation was probably through dissolution of Pb associated with exchangeable (EX), organic fraction (OC), acidic fraction (AC) and amorphous Fe and Al oxides-bound (OX) fraction and precipitation of pyromorphite-like minerals. Results suggested that the rock phosphate with small grain size was superior to that with large grain size for in situ remediation technology.

6-Hydroxydopamine-induced alterations in blood-brain barrier permeability

Vascular inflammation is well known for its ability to compromise the function of the blood--brain barrier (BBB). Whether inflammation on the parenchymal side of the barrier, such as that associated with Parkinson's-like dopamine (DA) neuron lesions, similarly disrupts BBB function, is unknown. We assessed BBB integrity by examining the leakage of FITC-labeled albumin or horseradish peroxidase from the vasculature into parenchyma in animals exposed to the DA neurotoxin 6-hydroxydopamine (6OHDA). Unilateral injections of 6OHDA into the striatum or the medial forebrain bundle produced increased leakage in the ipsilateral substantia nigra and striatum 10 and 34 days following 6OHDA. Microglia were markedly activated and DA neurons were reduced by the lesions. The areas of BBB leakage were associated with increased expression of P-glycoprotein and beta 3-integrin expression suggesting, respectively, a compensatory response to inflammation and possible angiogenesis. Behavioural studies revealed that domperidone, a DA antagonist that normally does not cross the BBB, attenuated apomorphine-induced stereotypic behaviour in animals with 6OHDA lesions. This suggests that drugs which normally have no effect in brain can enter following Parkinson-like lesions. These data suggest that the events associated with DA neuron loss compromise BBB function.

Yield and arsenate uptake of arbuscular mycorrhizal tomato colonized by Glomus mosseae BEG167 in As spiked soil under glasshouse conditions

A glasshouse pot experiment was conducted to study the effect of arbuscular mycorrhizal (AM) colonization by Glomus mosseae BEG167 on the yield and arsenate uptake of tomato plants in soil experimentally contaminated with five As levels (0, 25, 50, 75 and 150 mg kg(-1)). Mycorrhizal colonization (50-70% of root length) was little affected by As application and declined only in soil amended with 150 mg As kg(-1). Mycorrhizal colonization increased plant biomass at As application rates of 25, 50 and 75 mg kg(-1). Shoot As concentration increased with increasing As addition up to 50 mg kg(-1) but decreased with mycorrhizal colonization at As addition rates of 75 and 150 mg kg(-1). Shoot As uptake increased with mycorrhizal colonization at most As addition levels studied, but tended to decrease with addition of 150 mg As kg(-1). Total P uptake by mycorrhizal plants was elevated at As rates of 25, 50 and 75 mg kg(-1), and more P was allocated to the roots of mycorrhizal plants. Mycorrhizal plants had higher shoot and root P/As ratios at higher As application rates than did non-mycorrhizal controls. The soil of inoculated treatments had higher available As than uninoculated controls, and higher pH values at As addition levels of 25, 50 and 75 mg kg(-1). Mycorrhizal colonization may have increased plant resistance to potential As toxicity at the highest level of As contamination studied. Mycorrhizal tomato plants may have potential for phytoextraction of As from moderately contaminated soils or phytostabilization of more highly polluted sites.

Influence of the arbuscular mycorrhizal fungus Glomus mosseae on uptake of arsenate by the As hyperaccumulator fern Pteris vittata L

We report for the first time some effects of colonization by an arbuscular mycorrhizal (AM) fungus (Glomus mosseae) on the biomass and arsenate uptake of an As hyperaccumulator, Pteris vittata. Two arsenic levels (0 and 300 mg As kg(-1)) were applied to an already contaminated soil in pots with two compartments for plant and hyphal growth in a glasshouse experiment. Arsenic application had little or no effect on mycorrhizal colonization, which was about 50% of root length. Mycorrhizal colonization increased frond dry matter yield, lowered the root/frond weight ratio, and decreased frond As concentration by 33-38%. Nevertheless, transfer of As to fronds showed a 43% increase with mycorrhizal colonization at the higher soil As level. Frond As concentrations reached about 1.6 g kg(-1) (dry matter basis) in non-mycorrhizal plants in the As-amended soil. Mycorrhizal colonization elevated root P concentration at both soil As levels and mycorrhizal plants had higher P/As ratios in both fronds and roots than did non-mycorrhizal controls.

Soil to plant transfer of 238U, 226Ra and 232Th on a uranium mining-impacted soil from southeastern China

Both soil and plant samples of nine different plant species grown in soils from southeastern China contaminated with uranium mine tailings were analyzed for the plant uptake and translocation of 238U, 226Ra and 232Th. Substantial differences were observed in the soil-plant transfer factor (TF) among these radionuclides and plant species. Lupine (Lupinus albus) exhibited the highest uptake of 238U (TF value of 3.7x10(-2)), while Chinese mustard (Brassica chinensis) had the least (0.5x10(-2)). However, in the case of 226Ra and 232Th, the highest TFs were observed for white clover (Trifolium pratense) (3.4x10(-2)) and ryegrass (Lolium perenne) (2.1x10(-3)), respectively. 232Th in the tailings/soil mixture was less available for plant uptake than 226Ra or 238U, and this was especially evident for Chinese mustard and corn (Zea mays). The root/shoot (R/S) ratios obtained for different plants and radionuclides shown that Indian mustard had the smallest R/S ratios for both 226Ra (5.3+/-1.2) and 232Th (5.3+/-1.7), while the smallest R/S ratio for 238U was observed in clover (2.8+/-0.9).

[Ultrastructural localization of ATPase activity in fertile and sterile anther of rice (Oryza sativa L. cv. Marxie)]

Pb3 (po4)2-precipitation was used to study the ATPase activities both in fertile and sterile anthers of rice (Oryza sativa L. cv. Marxie). At big-vacuole pollen stage, tapetum of the fertile anthers showed high ATPase activity in their nuclei. In fertile pollen, ATPase was localized on the outside surface of the exine and in the nucleus both at big-vacuole and at bi-nucleate pollen stage. At late bi-nucleate pollen stage, a large amount of Pb3 (PO4)2 precipitated in endintine of the fertile pollen. In sterile anthers, tapetum was fully degenerated at big-vacuole pollen stage. In sterile pollen, ATPase was localized both on the plasmamembrane and in intine. These phenomena lasted to the bi-nucleate pollen stage. In addition, most of the sterile pollen did not show well-developed endintine. Based on the above results, we suggested that abortive tapetum could not provide enough nutrition for pollen development, and the high ATPase activity both on plasma membrane and in intine would likely result in ATP shortage in sterile anthers.

Cationic lipids enhanced cellular uptake and activity of bcl-2 antisense oligodeoxynucleotide G3139 in HL-60 cells

AIM

To explore the effect of cationic lipid 1,3-di-oleoyloxy-2-(6-carboxy-spermyl)-propylamid (DOSPER) on cellular uptake and activity of bcl-2 antisense oligodeoxynucleotide G3139 in HL-60 cells.

METHODS

The cell-associated mean fluorescence intensity and the percentage of cells with positive staining for Bcl-2 were measured by flow cytometry. The subcellular distribution of fluorescein isothiocyanate (FITC)-labeled G3139 was observed by fluorescence microscope and the bcl-2 mRNA level was detected by reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

(1) DOSPER increased cellular uptake of G3139 into HL-60 cells greatly. When DOSPER/G3139 (microg : microg) was 2 : 1, the uptake of G3139 reached top after treatment for 2 h and increased about 20 times compared with application of G3139 alone. In the presence of DOSPER, G3139 was localized in nucleus and cytosol with a bright spotted fluorescence staining. However, G3139 was localized in cytoplasm with faint fluorescence in the absence of DOSPER. (2) Cell-associated G3139 could be effluxed out of cells. After treated with G3139 in the presence of DOSPER for 4 h, the cell-associated G3139 could be fitted by C(t)=68.2e(-0.60) t+31.8e(-0.02) t (% of initial value), with a half-life of approximately 1.1 h. In the absence of DOSPER, the cell-associated G3139 could be fitted by C(t)=64.8e(-2.27) t+35.2e(-0.04) t, with a half-life of about 18 min. (3) In the presence of DOSPER, G3139 1.0 micromol/L specially reduced bcl-2 mRNA level, and Bcl-2 protein decreased from 97 % +/- 4 % to 70.6 % +/- 2.1 %.

CONCLUSION

DOSPER enhanced the activity of G3139 and it might be attributed to increase of the cellular uptake and change of the subcellular distribution of G3139.

Protective effect of ginsenoside Rg1 on dopamine-induced apoptosis in PC12 cells

AIM

To explore the possible molecular mechanism of exogenous dopamine-induced apoptosis in PC12 cells and the protective effect of ginsenoside Rg1.

METHODS

Flow cytometric assay was used to quantify the apoptotic cells and measure the percentage of cells with positive Bcl-2 and Bax proteins. The morphology of apoptotic cells was evaluated by transmission electron microscope. DNA fragmentation was observed by gel electrophoresis. Caspase-3 activity was determined by fluorescent spectrofluorometer and the expressive bcl-2 and bax mRNA by semiquantitative reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

Dopamine 0.15, 0.30, 0.45, and 0.60 mmol/L induced PC12 cell apoptosis from 1.1 % +/- 0.4 % (control) to 41 % +/- 3 %, 46.4 % +/ -2.7 %, 53 % +/ -3 %, and 64.5 % +/- 2.7 %, respectively. After treatment with dopamine 0.45 mmol/L following pretreatment with Rg1 10 micromol/L for 24 h, the percentage of apoptotic cells and caspase-3 activity decreased from 53 % +/- 3 % and 683 +/- 8 (mean fluorescence intensity, MFI) to 1.9 % +/- 0.6 % and 325 +/- 5, and the percentage of cells with positive Bcl-2 protein increased from 14.3 % +/- 1.1 % to 25.9 % +/- 1.6 %, however, the percentage of cells with positive Bax protein decreased from 48 % +/- 3 % to 35 % +/- 3 %, compared with group treated with DA 0.45 mmol/L alone.

CONCLUSION

Ginsenoside Rg1 protected PC12 cells against apoptosis by inhibiting the activation of caspase-3 and regulating the ratio of Bcl-2 to Bax protein.

Plant growth and cation composition of two cultivars of spring wheat (Triticum aestivum L.) differing in P uptake efficiency

Phosphorus (P)-zinc (Zn) interactions were investigated in two wheat cultivars (Brookton versus Krichauff) differing in P uptake efficiency. The experiment was done in a growth chamber. Rock phosphate (RP) or CaHPO4 (CaP) were used as P sources, and ammonium nitrate (AN) or nitrate only (NO) were used as nitrogen sources. Two Zn levels were used, 0.22 mg x kg(-1) (LZ) and 2.2 mg ZnSO4.7H2O x kg(-1) (HZ), respectively. P availability significantly affected plant biomass production, but Zn supply had little effect. Plants fed ammonium nitrate had significantly lower concentrations of cations than those fed nitrate only. Cultivar Brookton (with higher P uptake efficiency) consistently had lower concentrations of cations than cv. Krichauff (with low P uptake efficiency) under limited P supply. The differences in concentrations of cations increased with the decrease in P availability, but were not affected by Zn supply. The ratio of potassium in roots to shoots of cultivar Brookton was always higher than in cultivar Krichauff. Based on these findings, it is postulated that the lower concentrations of cations in cultivar Brookton are related to root exudation of organic anions, and a conceptual model is established to describe the regulation of root exudation of organic anions and concentrations of cations.

[Possible mechanism of the protective effects of ginsenoside Rg1 on apoptosis in PC12 cells]

AIM

To explore the possible mechanism of the protective effect of ginsenoside Rg1 on dopamine-induced apoptosis in PC12 cells.

METHODS

Flow cytometric assay was performed to quantify the apoptotic cells and detect the positive percentage of Bcl-2 and Bax proteins in PC12 cells. The expression of bcl-2 and bax mRNA was identified by reverse transcription polymerase chain reaction (RT-PCR). The CPP32 activity was measured by fluorescent spectrofluorometer.

RESULTS

Dopamine-induced apoptosis in PC12 cells was inhibited by pretreatment with 10 mumol.L-1 Rg1. Simultaneously, the expression of Bcl-2 protein and mRNA were increased, and the Bax protein and mRNA were decreased. The activation of CPP32 was inhibited after pretreatment with Rg1.

CONCLUSION

Rg1 protects against dopamine-induced apoptosis in PC12 cells and this effect might be attributed to its regulation of the ratio of Bcl-2 to Bax and its inhibition of the activation of CPP32.

Plant growth and cation composition of two cultivars of spring wheat (Triticum aestivum L.) differing in P uptake efficiency

Phosphorus (P)-zinc (Zn) interactions were investigated in two wheat cultivars (Brookton versus Krichauff) differing in P uptake efficiency. The experiment was done in a growth chamber. Rock phosphate (RP) or CaHPO4 (CaP) were used as P sources, and ammonium nitrate (AN) or nitrate only (NO) were used as nitrogen sources. Two Zn levels were used, 0.22 mg x kg(-1) (LZ) and 2.2 mg ZnSO4.7H2O x kg(-1) (HZ), respectively. P availability significantly affected plant biomass production, but Zn supply had little effect. Plants fed ammonium nitrate had significantly lower concentrations of cations than those fed nitrate only. Cultivar Brookton (with higher P uptake efficiency) consistently had lower concentrations of cations than cv. Krichauff (with low P uptake efficiency) under limited P supply. The differences in concentrations of cations increased with the decrease in P availability, but were not affected by Zn supply. The ratio of potassium in roots to shoots of cultivar Brookton was always higher than in cultivar Krichauff. Based on these findings, it is postulated that the lower concentrations of cations in cultivar Brookton are related to root exudation of organic anions, and a conceptual model is established to describe the regulation of root exudation of organic anions and concentrations of cations.

Plant growth and cation composition of two cultivars of spring wheat (Triticum aestivum L.) differing in P uptake efficiency

Phosphorus (P)-zinc (Zn) interactions were investigated in two wheat cultivars (Brookton versus Krichauff) differing in P uptake efficiency. The experiment was done in a growth chamber. Rock phosphate (RP) or CaHPO4 (CaP) were used as P sources, and ammonium nitrate (AN) or nitrate only (NO) were used as nitrogen sources. Two Zn levels were used, 0.22 mg x kg(-1) (LZ) and 2.2 mg ZnSO4.7H2O x kg(-1) (HZ), respectively. P availability significantly affected plant biomass production, but Zn supply had little effect. Plants fed ammonium nitrate had significantly lower concentrations of cations than those fed nitrate only. Cultivar Brookton (with higher P uptake efficiency) consistently had lower concentrations of cations than cv. Krichauff (with low P uptake efficiency) under limited P supply. The differences in concentrations of cations increased with the decrease in P availability, but were not affected by Zn supply. The ratio of potassium in roots to shoots of cultivar Brookton was always higher than in cultivar Krichauff. Based on these findings, it is postulated that the lower concentrations of cations in cultivar Brookton are related to root exudation of organic anions, and a conceptual model is established to describe the regulation of root exudation of organic anions and concentrations of cations.

Studies on the energy release of rice mitochondria under different conditions by means of microcalorimetry

The thermodynamic and kinetic behaviors of energy release of mitochondria isolated from rice (Oryza sative L.) were studied by using a LKB 2277 Bioactivity Monitor under different conditions. The thermogenesis curves of energy release of the rice mitochondria (which had been kept at 0-3 degrees C for 15 h and 40 day before the determination) were determined respectively at 25 and 30 degrees C, and the difference in shape of the thermogenesis curves and thermodynamic and kinetic characteristics were compared. The thermodynamic and kinetic parameters of energy release of the mitochondria in the thermogenesis increasing stage have been calculated, and the experimental thermokinetic equations of the thermogenesis have been established. The results indicated that the lower the temperature, the slower the energy release of the rice mitochondria. Both the thermogenesis and the energy release rate of the rice mitochondria increased after the mitochondria was kept at lower temperature for 40 days. One can use the methods to characterize the ability of the rice mitochondria to release energy under different conditions.

[RAPD analysis of the genome evolution in allopolyploid species in Aegilops]

RAPD analysis was performed by applying a set of 24 arbitrary primers to all the allopolyploids and their diploid progenitors in Aegilops L. The analysis based on 313 RAPD fragments revealed that the allopolyploids carrying D genome grouped with Ae. squarrosa (DD) in one cluster. The allopolyploids carrying U genome grouped with Ae. umbellulata (UU) in another cluster except Ae. juvenalis (DDMMUU), which grouped with Ae. squarrosa (DD). The allopolyploids did not cluster with the other diploids. The results indicated that the allopolyploids shared close relationship with Ae. squarrosa (DD) and Ae. umbellulata (UU), respectively. It proved that the D and U genomes altered relatively little from the diploid progenitors after the allopolyploids came into being, but the other genomes changed greatly.

[Construction of the physical map of Pi-2(t), a blast resistance gene in rice]

In an effort to clone a rice blast resistance gene, Pi-2(t), a BAC contig consisting of 22 BAC clones covering the whole Pi-2(t) region, was constructed using marker-based chromosome landing and chromosome walking. The genetic span of this physical map is 8 cM, but the physical size is 925 kb. The physical map forms the base of further isolation and cloning of Pi-2(t) gene, it will provide new markers for molecular marker-aided selection of new blast resistance materials in rice.

Effect of external potassium (K) supply on the uptake of 137Cs by spring wheat (Triticum aestivum cv. Tonic): a large-scale hydroponic study

A large-scale hydroponic experiment was carried out in a non-controlled greenhouse. Spring wheat plants were grown to maturity at four levels of external K concentration (2, 4, 20 and 40 mgl(-1)) and one concentration of radiocaesium (8 Bqml(-1)). Concentrations of K and radiocaesium in the growth solution were closely monitored, and replenishments were made upon depletion. K effectively competed with radiocaesium in terms of root uptake. Activity concentrations of radiocaesium in plants differed significantly between the four K treatments; the activity concentration at the lowest external K concentration being 100 times higher than that at the highest K level. The relationship between radiocaesium uptake and external K level could be described by a negative power function; this showed that when the K level reached around 12 mgl(-1), further increases in the external K level resulted only in slight changes in its inhibitory effect. As a result of this inhibitory effect of potassium supply, concentrations of radiocaesium in plant tissues, grains in particular, were greatly reduced at high external K concentration. Mechanisms involved in Cs-K interaction in root uptake are also discussed.

Oxidative stress before and after operation in patients with chronic cholecystitis containing gallstone

To study the relationship of oxidative, antioxidative constituents and antioxidases in blood with chronic cholecystitis containing gallstone, levels of lipoperoxides (LPO), nitric oxide (NO), vitamin C(VC), vitamin E (VE) and beta-carotene (beta-CAR) in plasma as well as level of LPO, activities of superoxide dismulase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in erythrocytes were investigated by spectrophotometric assay in 107 patients with this condition (PCg) and 100 healthy volunteers (HVs). Compared with HVs group, the average value of LPO and NO in plasma and that of LPO in erythrocytes of PCg group were significantly increased (P < 0.0001), while that of VC, VE and beta-CAR in plasma and the average activities of SOD, CAT and GSH-Px in erythrocytes were significantly decreased (P < 0.0001). Linear regression and correlation analysis for 107 preoperative PCg showed that the value of LPO and NO in plasma and that of LPO in erythrocytes of PCg gradually increased (P < 0.0001), representing a significant linear positive correlation. The value of VC, VE and beta-CAR in plasma and that of SOD, CAT and GSH-Px in erythrocytes of PCg gradually decreased (P < 0.0001), representing a significant linear negative correlation. Stepwise regression and correlation analysis for 107 preoperative PCg suggested that the closest correlation was observed between the course of disease and the value of NO and VC in plasma and that of SOD, GSH-Px and LPO in erythrocytes, r = 0.7306, F = 32.1408, P < 0.0001. Compared with the preoperative PCg group, the average value of LPO and NO in plasma and that of LPO in erythrocytes of the postoperative PCg group were significantly decreased (P < 0.0001). Furthermore, the average value of VC in plasma and that of SOD, CAT and GSH-Px in erythrocytes of the postoperative PCg group were significantly increased (P < 0.0001), whereas no significant difference was found between their average value of VE and beta-CAR in plasma. These findings suggested that oxidative stress was an aggravating pathological condition in PCg group. Therefore, we recommend that in treating PCg, antioxidants such as VC, VE, beta-CAR should be given in order to alleviate their potential oxidative damages.

Effect of potassium (K) supply on the uptake of 137Cs by spring wheat (Triticum aestivum cv. Tonic): a lysimeter study

A lysimeter experiment was carried out on a relatively infertile soil to examine the effect of potassium fertiliser application on the uptake of radiocaesium by spring wheat. Porous ceramic cups were used to obtain samples of soil solution. Results showed that the uptake of radiocaesium by spring wheat was reduced by the addition of potassium. However this inhibitory effect was less marked at later stages of plant growth due to factors such as the spatial variability of potassium within the soil, differences in root distribution down the soil profile and age-related demand for potassium by the plant. There was some evidence that a negative power function could be used to describe the relationship between the concentration of 137Cs in the plant and concentrations of potassium or 137Cs:K quotients in soil solution over the whole experimental period. Practical implications of potassium fertilisation in terms of reducing uptake of radiocaesium by crops are discussed.

Plant uptake of radiocaesium: a review of mechanisms, regulation and application

Soil contamination with radiocaesium (Cs) has a long-term radiological impact because it is readily transferred through food chains to human beings. Plant uptake is the major pathway for the migration of radiocaesium from soil to human diet. The plant-related factors that control the uptake of radiocaesium are reviewed. Of these, K supply exerts the greatest influence on Cs uptake from solution. It appears that the uptake of radiocaesium is operated mainly by two transport pathways on plant root cell membranes, namely the K(+) transporter and the K(+) channel pathway. Cationic interactions between K and Cs on isolated K-channels or K transporters are in agreement with studies using intact plants. The K(+) transporter functioning at low external potassium concentration (often <0.3 mM) shows little discrimination against Cs(+), while the K(+) channel is dominant at high external potassium concentration with high discrimination against Cs(+). Caesium has a high mobility within plants. Although radiocaesium is most likely taken up by the K transport systems within the plant, the Cs:K ratio is not uniform within the plant. Difference in internal Cs concentration (when expressed on a dry mass basis) may vary by a factor of 20 between different plant species grown under similar conditions. Phytoremediation may be a possible option to decontaminate radiocaesium-contaminated soils, but its major limitation is that it takes an excessively long time (tens of years) and produces large volumes of waste.

Soil contamination with radionuclides and potential remediation

Soils contaminated with radionuclides, particularly 137Cs and 90Sr, pose a long-term radiation hazard to human health through exposure via the foodchain and other pathways. Remediation of radionuclide-contaminated soils has become increasingly important. Removal of the contaminated surface soil (often up to 40 cm) or immobilization of radionuclides in soils by applying mineral and chemical amendments are physically difficult and not likely cost-effective in practicality. Reducing plant uptake of radionuclides, especially 137CS and 90Sr by competitive cations contained in chemical fertilizers has the general advantage in large scale, low-level contamination incidents on arable land, and has been widely practiced in central and Western Europe after the Chernobyl accident. Phytoextraction of radionuclides by specific plant species from contaminated sites has rapidly stimulated interest among industrialists as well as academics, and is considered to be a promising bio-remediation method. This paper examines the existing remediation approaches and discusses phytoextraction of radionuclides from contaminated soils in detail.

[Isolation and sequence analysis of a mitochondrial DNA fragment associated with CMS in Hong Lian type rice]

A CMS line specific mtDNA band TA1 was isolated by comparing the mtDNAs of CMS line and maintainer line using AFLP technique. The Northern blot analysis of the TA1 mtDNA fragment show that it transcripts only one RNA molecular each in CMS line, maintain line and the first filial generation, but the RNA moleculars are different among each other. By sequencing, the fragment is found to be 202 base pairs in length. It contains code ATG, ATT, AGA and AGG, two small repeated sequences 5'TGTAC3' and 5'ATTATTTT3' and one small inverted-repeated sequence 5'GGGAAACA3'. The results imply that the mtDNA fragment may be a coding region and may be relative to CMS of Hong Lian type rice.

Cytoplasmic amino and carboxyl domains form a wide intracellular vestibule in an inwardly rectifying potassium channel

We have studied the structural components and architecture of the intracellular vestibule of a strongly rectifying channel (Kir2.1) expressed in Xenopus oocytes. Putative vestibule-lining residues were identified by systematically examining covalent modification by sulfhydryl-specific reagents of cysteine residues engineered into two cytoplasmic regions. In a stretch of 33 amino acids in the amino terminus (from C54 to V86) and 22 amino acids in the carboxyl terminus (from R213 to S234), 15 and 11 residues, respectively, were found to be accessible to methanethiosulfonate ethylammonium (MTSEA) or methanethiosulfonate ethyltrimethylammonium (MTSET) and presumably project into the aqueous intracellular vestibule. The pattern of accessibility suggests that both stretches may adopt an extended loop structure. To explore the physical dimension of the intracellular vestibule, we covalently linked a constrained number (one to four) of positively charged moieties of different sizes to the E224 position and found that this vestibule region is sufficiently wide to accommodate four modifying groups with dimensions of 12 A x 10 A x 6 A. These results suggest that regions in both the amino and carboxyl domains of Kir2.1 channel form a long and wide intracellular vestibule that protrudes beyond the membrane into the cytoplasm.

Determination of the thermogenesis curves and studies of the thermodynamics and thermokinetics of seed germination

The thermogenesis curves of the germination of different rice and tree seeds were determined and studied by using a newly constructed microcalorimeter. The thermogenesis curves of the germination of the seeds demonstrate the existence of physiological triphasic patterns, which include imbibition, activation and growth stages in the germination process. The thermodynamics and thermokinetics of the main growth phase of the growth stage in the germination process have been studied. The growth heat effect (deltaH), the growth rate constant (k), the growth inhibitory factor (s) and deceleration rate constant (beta) have been determined and calculated, In addition, the experimental thermokinetic equations of the growth stage in the seed germination process have been established.

Nationwide survey of human parasite in China

A nationwide survey of human parasites in China was conducted during 1988-1992, with a coverage of 30 provinces/autonomous regions/municipalities (P/A/M). A total of 2,848 pilot sites in 726 counties were selected by random sampling, and 1,477,742 individuals residing on were surveyed by fecal examination. The status of paragonimiasis, hydatid diseases, cysticercosis and trichinellosis were summarized through data review. The overall infection rate of intestinal parasites was 62.6% whereas at provincial level, the highest infection rate (94.7%) was recovered in Hainan, and the lowest (17.5%) in Heilong-jiang. A high proportion (43.3%) of polyparasitism among the infected population (882,080) was revealed. Altogether 56 species of parasites comprising protozoa (19), trematode (16), cestodes (8), nematodes (12) and thorny-headed worm (1) were discovered. During the survey a new species and several new records were documented. The number of the population infected with common intestinal parasites was estimated. The diversities of parasite distribution were noted in different nationalities as well as in varied occupations.