GPI-anchored glutathione S-transferase as marker allows affinity sorting of transfection-positive cells

Cell transfection efficiency is still a limiting factor in gene function research. A method that allows isolation and enrichment of the transfection-positive cells is an effective solution. Here, we report a transfection-positive cell sorting system that utilizes GPI-anchored GST (Glutathione S-transferase) as a plasmid marker. The Glutathione S-transferase fusion protein will be expressed and displayed on the cell surface through GPI anchor, and hence permits the positive cells to be isolated using Glutathione (GSH) Magnetic Beads. We prove that the system works efficiently in both the adherent Lenti-X 293T cells and the suspension K-562 cells. The affinity cell sorting procedure efficiently enriched positive cells from 20% to 98% in K-562 cells. The applications in gene knockdown and overexpression experiments in K-562 cells dramatically enhanced the extent of gene alteration, with the gene knockdown efficiency increasing from 7% to 60% and the gene overexpression level rising from 47 to 253 times. This Glutathione S-transferase affinity transfection-positive cell sorting method is simple and fast to operate, large-instrument free, low cost, and hence possesses great potential in gene function study in vitro.

A nomogram integrating ferroptosis-and immune-related biomarker for prediction of prognosis and diagnosis in kidney renal clear cell carcinoma

OBJECTIVE

Approximately 60% of patients with kidney renal clear cell carcinoma (KIRC) die within the first 2-3 years. The prognosis for patients with KIRC and its metastases is poor. Ferroptosis and providing immunity are novel treatment targets for several cancers, including KIRC. Therefore, it is important to identify suitable ferroptosis- and immune-related signatures to predict the prognosis and diagnosis of patients with KIRC.

MATERIALS AND METHODS

The corresponding data of patients with KIRC were obtained from the Cancer Genome Atlas. Univariate and multivariate Cox regression analyses were used to screen candidate biomarkers in patients with KIRC.

RESULTS

We found that four FI-DEGs (BID, MET, LTB4R, and HMOX1) were independently associated with the overall survival of patients with KIRC. The prognosis and diagnosis model constructed using these four biomarkers could predict the outcome of KIRC, as measured by the receiver operating characteristic analyses.

CONCLUSIONS

We identified 4 FI-DEGs that could be used as biomarkers in patients with KIRC. The present study not only contributes to understanding the roles of ferroptosis and immunity in the development of KIRC, but also to the diagnosis and prognosis of KIRC, although it remains to be further studied.

A Gene Transfer-Positive Cell Sorting System Utilizing Membrane-Anchoring Affinity Tag

Gene delivery efficiency is an essential limit factor in gene study and gene therapy, especially for cells that are hard for gene transfer. Here we develop an affinity cell sorting system that allows efficient enrichment of gene transfer-positive cells. The system expresses an enhanced green fluorescent protein (EGFP) fused with an N-terminal high-affinity Twin-Strep-Tag (TST) that will be anchored to the cell membrane at the out-surface through a glycosylphosphatidylinositol (GPI) membrane-anchoring structure. The EGFP permits microscopy and flow cytometry analysis of the gene transfer-positive cells, and the TST tag at the N terminal of EGFP allows efficient affinity sorting of the positive cells using Strep-Tactin magnetic beads. The cell sorting system enables efficient isolation of gene transfer-positive cells in a simple, convenient, and fast manner. Cell sorting on transfected K-562 cells resulted in a final positive cell percentage of up to 95.0% with a positive cell enrichment fold of 5.8 times. The applications in gene overexpression experiments could dramatically increase the gene overexpression fold from 10 times to 58 times, and in shRNA gene knockdown experiments, cell sorting increased the gene knockdown efficiency from 12% to 53%. In addition, cell sorting in CRISPR/Cas9 genome editing experiments allowed more significant gene modification, with an editing percentage increasing from 20% to 79%. The gene transfer-positive cell sorting system holds great potential for all gene transfer studies, especially on those hard-to-transfect cells.

[Clinicopathologic analysis of extranodal non-hodgkin lymphoma of the sinonasal cavities: a 15-case report]

Objective:To investigate the clinical manifestation, imaging and histological features of different histological subtypes of non-Hodgkin's lymphoma of nasal cavity and paranasal sinuses.Method:Fifteen NHL patients of the sinonasal region were collected from the Department of Otolaryngology of Peking University Third Hospital from 2010 to 2016. HE staining and immunohistochemical staining were performed. The clinical characteristics and imaging features of different subtypes were described and analyzed.Result::We analyzed a total of 6 patients with localized sinonasal diffuse large B cell lymphoma and 9 patients with localized sinonasal extranodal NK/T cell lymphoma. The age distribution for these two subtypes is very distinct. The median age of the patients with localized sinonasal extranodal NK/T cell lymphoma was 39 years. There were 5 males and 4 females. Nine sinonasal NHLs were NK/T-cell lymphoma, nasal type, all of which were infected with EBV. The median age of the patients with localized sinonasal diffuse large B cell lymphoma was 64 years. There were 3males and 3 females. Symptoms for patients with SN-DLBCL and SN-ENKTL were significantly different in epiphora, proptosis, diplopia and nasal congestion (P=0.18, 0.004, 0.18, 0.18). Imaging features for patients with SN-DLBCL and SN-ENKTL were significantly different in tumor extended to orbit and inferior turbinate (P>0.05). Positive staining for CD 56 was detected in 9 patients, for CD 3 in 9 patients, for EBER in 9 patients. The Hans algorithm identified 1 patient with the germinal center B-cell (GCB) subtype and 5 with the non-GCB subtype.Compared with the control group, the observation group was significantly better than the control group (P < 0.01).Conclusion:Early symptoms of epiphora, proptosis, diplopia, and images finding with orbital invasion should be highly suspected of diffuse large B cell lymphoma. Positive staining for CD 56 and EBER were detected in all patients with extranodal NK/T cell lymphoma, and positive staining for CD20 was detected in all patients with SN-DLBCL.

Effects of Bacillus subtilis and nanohydroxyapatite on the metal accumulation and microbial diversity of rapeseed (Brassica campestris L.) for the remediation of cadmium-contaminated soil

This study investigated the effects of the co-application of Bacillus subtilis and nanohydroxyapatite (NHAP) on plant growth, soil cadmium (Cd) dynamics, and the microbiological characteristics (such as enzyme activity and bacterial species richness) of the rhizosphere soil. Rapeseed was used as a model plant in pot experiments. Different concentrations of B. subtilis and 0.5% NHAP were applied alone and in combination to Cd-contaminated soil. The Cd contents in soils and plants as well as the rhizospheric microorganism diversity were assessed. The addition of B. subtilis or NHAP alone increased the soil Cd content and decreased the plant Cd content, while their co-application more effectively increased the soil and plant Cd contents than either treatment alone. B. subtilis and NHAP reduced the plant Cd content by 43.15-57.04% compared with that in the control. Rhizosphere community richness and bacterial diversity were significantly increased after co-application of B. subtilis and NHAP. Co-application of B. subtilis and NHAP effectively promoted rapeseed growth and improved Cd-contaminated soil remediation.

Effect of nanohydroxyapatite on cadmium leaching and environmental risks under simulated acid rain

Cadmium (Cd) contamination in soil is a global environmental pollution issue. Nanohydroxyapatite (NHAP) has been used in soil remediation to immobilize cadmium in contaminated soils. However, the effect of acid rain on the export of cadmium from topsoil and its behavior in deep soil and leachate is unclear. In this study, column experiments and development of parsimonious model were performed to estimate Cd leaching behavior from topsoil and environmental risk of groundwater after 0.5% NHAP remediation. Four leaching events were performed and total Cd, different fractions of Cd determined by sequential extraction procedure and pH were determined for each leaching. The results show that with the export of Cd in topsoil, the total Cd concentration in soil at different depths had the following vertical distributions: 0-5 cm > 5-10 cm > 10-15 cm > 15-20 cm. NHAP treatment increased the soil pH and decreased Cd leaching loss by 56.45% compared to the control, and the results fit the parabolic diffusion model. With sequential extraction it was observed that NHAP application increased the residual fraction of cadmium in soil. After leaching, there was a positive correlation between soil pH and Cd concentration with regards to the exchangeable, reducible, oxidizable and residual Cd fractions. The parabolic diffusion model showed that Cd-contaminated soil with NHAP remediation is harmless to humans after sufficient remediation duration, whereas the resultant concentrations from the CK treatment could be toxic. The results indicate that nanohydroxyapatite could significantly reduce the bioavailability of cadmium and the environmental risk. However, the release of Ca and P from the dissolution of NHAP should be carefully studied as this will impact the mobilization of Cd or colloid Cd, and high leaching of P may result in P-induced eutrophication risk.

Influence of Nano-Hydroxyapatite on the Metal Bioavailability, Plant Metal Accumulation and Root Exudates of Ryegrass for Phytoremediation in Lead-Polluted Soil

Lead is recognized as one of the most widespread toxic metal contaminants and pervasive environmental health concerns in the environment. In this paper, the effects of nano-hydroxyapatite (NHAP) on remediation in artificially Pb-contaminated soils and ryegrass were studied in a pot experiment. The addition of NHAP decreased the water- and acid-soluble, exchangeable, and reducible fractions of Pb, extracted using the Community Bureau of Reference (BCR) method, whilst greatly increasing the residual fraction of Pb. Oxidizable Pb was increased slightly. No significant increase in soil pH was caused by the application of NHAP. Compared to conditions without NHAP, the addition of NHAP decreased the Pb content in ryegrass shoots and roots by 13.19-20.3% and 2.86-21.1%, respectively. Therefore, the application of NHAP reduced the mobility and bioavailability of Pb in the soil. In addition, the application of NHAP improved the fresh weight of shoots and roots, and promoted the growth of ryegrass. NHAP played a positive role in stimulating ryegrass to secrete tartaric acid.

[Clinically predictive factors of Gleason score upgrading in patients after radical prostatectomy]

OBJECTIVE

To assess the discrepancy between preoperative needle biopsy (NB) Gleason score and pathological specimen Gleason score (GS) after radical prostatectomy, and to explore the risk factors of postoperative upgrading of GS.

METHODS

We retrospectively evaluated 160 patients who suffered from biopsy proved prostatic carcinoma and performed radical prostatectomy. Age of the patients was 57-82 years, with the average age of 71.6; prebiopsy prostate specific antigen (PSA) was 0.31-40.32 μg/L,with the average PSA of 11.29 μg/L; body mass index (BMI) was 16.41-32.04 kg/m², with the average BMI of 23.63 kg/m²; prostate volume (PV) was 9.52-148.46 mL, with the average PV of 40.19 mL. All the patients included in the study had complete information for clinical variables, including age, BMI, prebiopsy PSA level, PV, number of biopsy cores obtained, percentage, clinical stage, and biopsy GS. Grading of NB Gleason score was compared with their corresponding radical prostatectomy specimens, and the discrepancy between the NB and prostatectomy specimens GS assessed. Upgrading was defined as any increase in the pathological GS over that of the biopsy GS as a total sum of primary and secondary grades or a change in the order of primary and secondary grades towards higher ones. Univariable and multivariable Logistic regression analyses were used to identify predictors of pathological grading changes.

RESULTS

Of the 160 patients, the specimen GS was upgraded in 49 (30.6%) patients and remained with no change in 82 (51.3%) patients. Univariate and multivariate regression analysis showed that prostate volume and biopsy GS were independent predictors with postoperative upgrading of GS. Age, BMI, PSA before needle biopsy, clinical stage and needle number showed no statistical significance (P>0.05).

CONCLUSION

Lower biopsy GS and smaller prostate volume are increased risks for clinically upgrading of GS after radical prostatectomy. This fact should be kept in mind when deciding on therapy decisions for patients with prostate cancer.

Nano-hydroxyapatite alleviates the detrimental effects of heavy metals on plant growth and soil microbes in e-waste-contaminated soil

The crude recycling activities of e-waste have led to the severe and complex contamination of e-waste workshop topsoil (0-10 cm) by heavy metals. After nano-hydroxyapatite (NHAp) application in June 2013, plant and soil samples were obtained in November 2013, December 2013, March 2014 and June 2014. The results showed that NHAp effectively reduced the concentration of CaCl2-extractable Pb, Cu, Cd, and Zn in the topsoil and significantly reduced the metal content in ryegrass and also increased the plant biomass compared with that of the control. Moreover, the concentrations of CaCl2-extractable metals in the soil decreased with increasing NHAp. NHAp application also increased the activities of soil urease, phosphatase and dehydrogenase. Moreover, the soil bacterial diversity and community structure were also altered after NHAp application. Particularly, Stenotrophomonas sp. and Bacteroides percentages were increased. Our work proves that NHAp application can alleviate the detrimental effects of heavy metals on plants grown in e-waste-contaminated soil and soil enzyme activities, as well as soil microbial diversity.

[Clinically predictive factors of Gleason score upgrading in patients after radical prostatectomy]

OBJECTIVE

To assess the discrepancy between preoperative needle biopsy (NB) Gleason score and pathological specimen Gleason score (GS) after radical prostatectomy, and to explore the risk factors of postoperative upgrading of GS.

METHODS

We retrospectively evaluated 160 patients who suffered from biopsy proved prostatic carcinoma and performed radical prostatectomy. Age of the patients was 57-82 years, with the average age of 71.6; prebiopsy prostate specific antigen (PSA) was 0.31-40.32 μg/L,with the average PSA of 11.29 μg/L; body mass index (BMI) was 16.41-32.04 kg/m(2), with the average BMI of 23.63 kg/m(2); prostate volume (PV) was 9.52-148.46 mL, with the average PV of 40.19 mL. All the patients included in the study had complete information for clinical variables, including age, BMI, prebiopsy PSA level, PV, number of biopsy cores obtained, percentage, clinical stage, and biopsy GS. Grading of NB Gleason score was compared with their corresponding radical prostatectomy specimens, and the discrepancy between the NB and prostatectomy specimens GS assessed. Upgrading was defined as any increase in the pathological GS over that of the biopsy GS as a total sum of primary and secondary grades or a change in the order of primary and secondary grades towards higher ones. Univariable and multivariable Logistic regression analyses were used to identify predictors of pathological grading changes.

RESULTS

Of the 160 patients, the specimen GS was upgraded in 49 (30.6%) patients and remained with no change in 82 (51.3%) patients. Univariate and multivariate regression analysis showed that prostate volume and biopsy GS were independent predictors with postoperative upgrading of GS. Age, BMI, PSA before needle biopsy, clinical stage and needle number showed no statistical significance (P>0.05).

CONCLUSION

Lower biopsy GS and smaller prostate volume are increased risks for clinically upgrading of GS after radical prostatectomy. This fact should be kept in mind when deciding on therapy decisions for patients with prostate cancer.

Impact of nanometer hydroxyapatite on seed germination and root border cell characteristics

Nanometer hydroxyapatite is beneficial to cucumber seeds and seedlings at concentrations less than 2000 mg L⁻¹.

Instrument development and validation of the stroke pre-hospital delay behavior intention scale in a Chinese urban population

Background

Several stroke impairment scales are currently available for stroke patients but none of them provide information regarding the pre-stroke behavioral intentions of high-risk stroke patients and their relatives. This study’s objective was to generate and validate a new written tool, the Stroke Pre-hospital Delay Behavior Intention (SPDBI) scale. It is suitable for use with high-risk stroke patients and their relatives to predict the likelihood of pre-hospital delay.

Methods

From a review of related studies, we formulated a prototype scale. We interviewed ten stroke patients in a semi-structured iterative process that included interviews with experts, high-risk patients, and their family members. Then, we pretested and filtered items. We next used a large sample size and factor analysis to determine the scale’s structure. Finally, we checked the reliability and validity of the scale.

Results

We identified five sub-domains (stroke warning signs, non-treatment justification, symptom attributions, habitual response style, and emergency system use). The SPDBI demonstrated good internal consistency and test-retest reliability (Cronbach’s α =0.808; Intraclass Correlation Coefficient [ICC] =0.797).

Conclusions

This SPDBI scale is a reliable, and valid measure of the likeliness of pre-hospital delay in high-risk stroke patients and their family members. It may provide scientific assessment for targeted health education intervention.

Electronic supplementary material

The online version of this article (doi:10.1186/s12955-014-0170-8) contains supplementary material, which is available to authorized users.

Development and validation of the Pre-hospital Stroke Symptoms Coping Test

Background and Purpose

Measures of specific knowledge of coping with pre-hospital stroke symptoms can help educate high-risk patients and family caregivers. This study aimed to develop and validate the Pre-hospital Stroke Symptoms Coping Test (PSSCT).

Materials and Methods

Reliability and validity were analyzed using multiple data sources. The Delphi expert consultation method was applied to assess the test’s surface validity and content validity index. The final edition of the 19-item PSSCT contained 3 sections assessing coping with typical symptoms and symptoms associated with vomiting and twitching. Its psychometric properties were investigated in a community sample of 300 high-risk patients and family members.

Results

The PSSCT was readily accepted by participants. It demonstrated adequate surface validity and content validity, and good internal consistency (KR₂₀ = 0.822) and test-retest reliability (0.769), with difficulty (P) and degree of differentiation (D) ranges of 0.28–0.83 and 0.15–0.66, respectively. It was also able to distinguish between individuals who had/had not experienced a stroke. Experienced individuals scored significantly higher overall and on coping with typical symptoms and twitching (P<0.01).

Conclusions

The PSSCT can practically and directly assess critical knowledge regarding coping with pre-hospital stroke symptoms and has good reliability and validity.

The Changes of Muscle FGF-6 Expression at Different Time Points after Exercise-induced Muscle Damage

OBJECTIVE

To investigate the changes of fibroblast growth factor (FGF)-6 expression in the regeneration and repair process after exercise-induced muscle damage (EIMD) and the relationship with skeletal muscle regeneration and repair.

METHODS

The expression of FGF-6 at different time points was examined by reverse transcription-polymerase chain reaction (PCR) and immunohistochemistry staining after a downhill treadmill exercise. Skeletal muscle injury and regeneration at different times after EIMD was assessed by haematoxylin and eosin (H and E) staining.

RESULTS

The FGF-6 protein expression was initially elevated and followed by a gradual reduction, while the changes of FGF-6 mRNA were almost all raised after the treadmill exercise.

CONCLUSION

The results point out that FGF-6 is closely related to skeletal muscle regeneration and repair, probably implying a dual function in muscle regeneration.

Uptake of polycyclic aromatic hydrocarbons by maize plants

Roots and above-ground parts (tops) of maize plants, comprising cuticles, leaves and stems, have been exposed separately to polycyclic aromatic hydrocarbons (PAHs) by means of air-tight bicameral exposure devices. Maize roots and tops of plants directly accumulate PAHs from aqueous solutions and from air in proportion to exposure levels. Root and leaf concentration factors (log RCF and log LCF) are log-linear functions of log-based octanol-water partition coefficient (log Kow) and log-based octanol-air partition coefficient (log Koa). The PAHs' concentrations among cuticles, leaves and stems display good correlations with each other. PAH concentrations in each part of the plant tested correlated positively with atmospheric PAHs' concentrations. Comparisons between PAHs' concentrations of root epidermis and root tissue showed similar correlations. Bulk concentrations of contaminants in various plant tissues differed greatly, but these differences disappeared after normalization to lipid contents suggesting lipid-based partitioning of PAHs among maize tissues.

Source apportionment of polycyclic aromatic hydrocarbons in surface soil in Tianjin, China

Principal component analysis and multiple linear regression were applied to apportion sources of polycyclic aromatic hydrocarbons (PAHs) in surface soils of Tianjin, China based on the measured PAH concentrations of 188 surface soil samples. Four principal components were identified representing coal combustion, petroleum, coke oven plus biomass burning, and chemical industry discharge, respectively. The contributions of major sources were quantified as 41% from coal, 20% from petroleum, and 39% from coking and biomass, which are compatible with PAH emissions estimated based on fuel consumption and emission factors. When the study area was divided into three zones with distinctive differences in soil PAH concentration and profile, different source features were unveiled. For the industrialized Tanggu-Hangu zone, the major contributors were cooking (43%), coal (37%) and vehicle exhaust (20%). In rural area, however, in addition to the three main sources, biomass burning was also important (13%). In urban-suburban zone, incineration accounted for one fourth of the total.

A two-compartment exposure device for foliar uptake study

An airtight two-chamber exposure devise was designed for investigating foliar uptake of polycyclic aromatic hydrocarbons (PAHs) by plants. The upper and the bottom chambers of the device were air-tightly separated by an aluminum foil and the plant aerial tissues and roots were exposed in the two chambers, respectively. The device was tested using maize exposed to several PAH species. Positive correlations between air and aerial tissue concentrations of the exposed PAH species were revealed. PAHs spiking in the culture solution had no influence on the leaf concentrations.

Source diagnostics of polycyclic aromatic hydrocarbons based on species ratios: a multimedia approach

Often, the sources of polycyclic aromatic hydrocarbons (PAHs) in environmental media can be identified by comparing the ratios of concentrations of selected pairs of PAH congeners in the source emissions to the ratios in the contaminated environmental media. However, these ratios can be altered significantly due to differences in the transport of the PAH compounds in a multimedia environment. To examine such changes, a fugacity model was applied to PAH ratios in a model environment. A linear relationship between the rate of emission and the bulk media concentration was identified for each PAH compound in an environmental medium at steady state and was quantified by a receptor-to-source ratio (RRS). It was demonstrated that the RRS values of the two congeners usually differ significantly. Consequentially, PAH ratios changed remarkably from the source emissions to various environmental media. A site-specific rectification factor (RF) was defined as the ratio of the two RRS values of the paired congeners for a specific PAH ratio in a given medium, which can be applied to account for the ratio changes in a multimedia environment. The PAH ratio changes were further verified with the surface soil data collected from Tianjin, China, and the observed changes of PAH ratios were compared favorably with the model predictions. The sensitivity analysis revealed that PAH ratios of the low molecular weight compounds were less stable. The most influential parameters controlling PAH ratios were those pertaining to dry precipitation, surface-to-air diffusion, degradation in air and water, and exchange between water and sediment.

Human exposure and health risk of alpha-, beta-, gamma- and delta-hexachlorocyclohexane (HCHs) in Tianjin, China

The dynamic exposures to HCHs of individuals born between the years 1913 and 1993 in Tianjin have been simulated by connecting a fugacity model (IV) with a multimedia exposure model. Ingestion is the most important pathway for human beings to take up HCHs, and concentrations in the human body correlate with body weight changes. Accumulations of HCHs were derived assuming that the degradation in human body behaved linearly. The health risk of exposure to HCHs was measured using cancer risk and loss of life expectancy (LLE), and LLE was modified from its original definition to incorporate a dynamic calculation that takes variances in exposure into account. Monte-Carlo simulations were run to analyze the uncertainties of the model.

Contamination of rivers in Tianjin, China by polycyclic aromatic hydrocarbons

Tianjin urban/industrial complex is highly polluted by some persistent organic pollutants. In this study, the levels of 16 priority polycyclic aromatic hydrocarbons (PAHs) were tested in sediment, water, and suspended particulate matter (SPM) samples in 10 rivers in Tianjin. The total concentration of 16 PAHs varied from 0.787 to 1943 microg/g dry weight in sediment, from 45.81 to 1272 ng/L in water, and from 0.938 to 64.2 microg/g dry weight in SPM. The levels of PAHs in these media are high in comparison with values reported from other river and marine systems. Variability of total concentrations of PAHs in sediment, water, and SPM from nine different rivers is consistent with each other. No obvious trends of total PAHs concentration variations were found between upstream and downstream sediment, water, and SPM samples for most rivers, which indicate local inputs and disturbances along these rivers. The spatial distributions of three-phase PAHs are very similar to each other, and they are also similar to those found in topsoil. However, their chemical profiles are significantly different from that of topsoil. The change of profiles is consistent with the different aqueous transport capability of 16 PAHs. Low molecular weight PAHs predomination suggests a relatively recent local source and coal combustion source of PAHs in the study area.

Inhibition of myogenesis by depletion of the glycogen-associated regulatory subunit of protein phosphatase-1 in rat skeletal muscle cells

In this study, we examined the role of the glycogen-associated regulatory subunit of protein phosphatase-1 (PP-1(G)) in L6 rat skeletal muscle cell myogenesis. The level of PP-1(G) was depleted by transfection with an inducible antisense-oriented PP-1(G) gene. Western blot analysis of the PP-1(G)-depleted cell line revealed a >90% depletion of PP-1(G) protein and a 45% reduction in cellular PP-1 activity and abolished the ability of L6 myoblasts to differentiate into multinucleated myotubes. PP-1(G)-depleted cells also exhibited a marked reduction in the expression of the differentiation marker myogenin as well as creatine kinase. After 7 days in culture, PP-1(G)-depleted cells sustained myoblast levels of inhibitor of differentiation-2, whereas control L6 cells had a severely lower inhibitor of differentiation-2 level and progressed into myotubes. Myoblasts were unable to exit the cell cycle, as measured by the impaired induction of p27 cyclin-dependent kinase inhibitor, a >2-fold increase in DNA synthesis, and elevated levels of phosphorylated retinoblastoma protein (pRb). Replacement of the PP-1(G) gene restored PP-1(G) protein expression, PP-1 enzymatic activity, and the ability to differentiate into myotubes. We conclude that PP-1(G) plays a definite role in L6 myogenesis via its regulation of PP-1 catalytic activity.

[A case-control study on Guillain-Barre syndrome in children of North China]

OBJECTIVE

This study aimed at exploring the risk factors for Guillain-Barre syndrome (GBS).

METHODS

A case-control study design was used with 51 cases of GBS, diagnosed based on their symptoms, signs and electrophysiological examinations and exclusion of poliomyelitis and other acute flaccid paralysis, and 51 controls matched on age, sex and resident village. Serum IgG antibodies specific for Campylobacter jejuni were determined for all the subjects by enzyme-linked immunosorbent assay (ELISA) with a preparation of surface antigen of C. jejuni C(1) strain isolated from the patients and prevalent in north China. Each case and control were interviewed with his/her parents or guardians by a trained interviewer using an ad hoc questionnaire, including his/her demographic information, socioeconomic status, onset of the illness, and potential risk factors in their environment and personal hygiene. Data were analyzed with SAS software release 6.04 in a microcomputer.

RESULTS

GBS was associated with a few factors, such as residential areas (45 of the 51 cases living in the rural areas, accounting for 88.2% of the total), polio and hepatitis B vaccine immunization before onset of the illness (with ORs of 7.27 and 3.14, respectively), no hand washing after defecation and before meals (with an OR of 6.15) and getting cold and going to the river or lake site before onset of the illness (with ORs of 13.75 and 12.20, respectively). Infection with Campylobacter jejuni associated strongly with the illness (with an OR of 9.5, P < 0.001). Thirty-five of the 51 cases had precursor symptoms before onset of the illness (68.6%).

CONCLUSION

It suggests that occurrence of GBS may correlate to infection with Campylobacter jejuni and poor personal hygiene in children.

Effect of calcitonin on calcium transport by the luminal and basolateral membranes of the rabbit nephron

In the rabbit, calcitonin has been shown to enhance calcium (Ca2+) reabsorption in the early distal tubule. The aim of the present study was to investigate the mechanism of this action, using isolated luminal and basolateral membranes of distal tubules. The tubule suspensions were preincubated in the presence or absence of 10(-7) M calcitonin. The luminal or basolateral membranes were subsequently purified and 45Ca transport through the vesicles was measured using the rapid filtration technique. Results were compared with those obtained from proximal tubule membranes. In the proximal tubules, calcitonin had no effect on Ca2+ uptake by luminal membranes. In the distal tubules, the presence of Na+ in the incubation medium strongly decreased the uptake of Ca2+ by luminal membranes. Preincubation of distal tubules with calcitonin partially restored this uptake. We previously reported a dual kinetics of Ca2+ uptake by the distal luminal membranes. Calcitonin enhanced Ca2+ transport by the low affinity component, increasing the Vmax and leaving the K(m) unchanged. Renal calcitonin receptors usually couple to both adenylate cyclase and phospholipase C. To determine through which messenger(s) calcitonin enhances Ca2+ transport by the distal tubules, we first confirmed that the hormone stimulates cAMP and IP3 release. Incubation of the distal tubules with 10(-7) M calcitonin significantly increased both messengers. In contrast, calcitonin did not influence the IP3 nor the cAMP content of proximal tubules. Therefore, we studied the actions of cAMP and phorbol 12-myristate 13 acetate (PMA) on Ca2+ transport by the distal luminal membranes. Incubation of distal tubule suspensions with dibutyryl cAMP significantly increased Ca2+ uptake by the luminal membranes. However, incubation of these tubules with various concentrations of PMA (10 nM, 100 nM and 1 microM) had no effect on this uptake. Calcitonin also influenced Ca2+ transport by the distal basolateral membrane. Incubation of distal tubule suspensions with 10(-7) M calcitonin activated the Na+/Ca2+ exchanger activity, almost doubling the Na+ dependent Ca2+ uptake. Here again this action was mimicked by cAMP. We conclude that calcitonin increases Ca2+ transport by the distal tubule through two mechanisms: the opening of low affinity Ca2+ channels in the luminal membrane and the stimulation of the Na+/Ca2+ exchanger in the basolateral membrane, both actions depending on the activation of adenylate cyclase.

[Chemical constituents of seeds of Camellia sinensis var. assamica]

Five compounds were isolated from the acid-hydrolytic products of n-butanol extract and ethanol extract of the seeds of Camellia sinensis var. assamica. Their structures were elucidated by chemical and spectroscopic analyses as octacosane, three new acyl-sapogenins: 22-O-angeloyl theasapogenol B, 22-O-angeloyl theasapogenol E and 22-O-angeloyl theasapogenol A, and naringenin respectively.