[Efficacy of adjuvant programmed cell death 1 (PD-1) monoclonal antibody immunotherapy in Chinese patients with resected stage Ⅱ-Ⅲ melanoma]

Objective: To explore the efficacy of adjuvant programmed cell death 1 (PD-1) monoclonal antibody immunotherapy in Chinese patients with resected stage Ⅱ-Ⅲ melanoma. Methods: A total of 296 patients who underwent radical surgery for stage Ⅱ-Ⅲ cutaneous orlimb melanoma at Fudan University Shanghai Cancer Center and Shanghai Electric Power Hospital between 2017 and 2021 and received adjuvant PD-1 monoclonal antibody immunotherapy, low-dose interferon (IFN), or observational follow-up were enrolled in this study. Patients were divided into the PD-1 monoclonal antibody group (164 cases) and the IFN or observation group (IFN/OBS group, 132 cases) based on postoperative adjuvant treatment methods. Patients' disease recurrence and survival were observed. Results: Among the 296 patients, 77 had cutaneous melanoma and 219 had limb melanoma; 110 were stage Ⅱ and 186 were stage Ⅲ. Among stage Ⅱ patients, the median recurrence-free survival (RFS) in the PD-1 monoclonal antibody group (46 cases) did not reach, while the median RFS in the IFN/OBS group (64 cases) was 36 months. The 1-year RFS rates were 85.3% and 92.1% and the 2-year RFS rates were 71.9% and 63.7% in the PD-1 monoclonal antibody group and the IFN/OBS group, respectively, with no statistically significant difference (P=0.394). Among stage Ⅲ patients, the median RFS rates in the PD-1 monoclonal antibody group (118 cases) and the IFN/OBS group (68 cases) were 23 and 13 months, respectively. The 1-year RFS rates were 70.0% and 51.8% and the 2-year RFS rates were 51.8% and 35.1%in the PD-1 monoclonal antibody group and the IFN/OBS group, respectively, with a statistically significant difference (P=0.010). Stratified analysis showed that the advantage of PD-1 monoclonal antibody adjuvant therapy in improving RFS persisted in the subgroups of primary ulceration (HR=0.558, 95% CI: 0.348-0.893), lymph node macroscopic metastasis (HR=0.486, 95% CI: 0.285-0.828), stage ⅢC (HR=0.389, 95% CI: 0.24-0.63), and the subgroup without BRAF/c-Kit/NRAS gene mutations (HR=0.347, 95% CI: 0.171-0.706). In terms of recurrence patterns, in stage Ⅱ patients, the recurrence and metastasis rate was 15.2% (7/46) in the PD-1 monoclonal antibody group, significantly lower than the IFN/OBS group [43.8% (28/64), P=0.002]. In stage Ⅲ melanoma patients, the recurrence and metastasis rate was 42.4% (50/118) in the PD-1 monoclonal antibody group, also lower than the IFN/OBS group [63.2% (43/68), P=0.006]. Conclusions: In real-world settings, compared with patients receiving low-dose IFN adjuvant therapy or observational follow-up, PD-1 monoclonal antibody immunotherapy can reduce the recurrence and metastasis rate of cutaneous and limb melanoma, and prolong the postoperative RFS of stage Ⅲ cutaneous and limb melanoma patients. Patients with a heavier tumor burden benefit more from immunotherapy.

Complement C3-Deficiency-Induced Constipation in FVB/N-C3em1Hlee/Korl Knockout Mice Was Significantly Relieved by Uridine and Liriope platyphylla L. Extracts

Complement component 3 (C3) deficiency has recently been known as a cause of constipation, without studies on the therapeutic efficacy. To evaluate the therapeutic agents against C3-deficiency-induced constipation, improvements in the constipation-related parameters and the associated molecular mechanisms were examined in FVB/N-C3em1Hlee/Korl knockout (C3 KO) mice treated with uridine (Urd) and the aqueous extract of Liriope platyphylla L. (AEtLP) with laxative activity. The stool parameters and gastrointestinal (GI) transit were increased in Urd- and AEtLP-treated C3 KO mice compared with the vehicle (Veh)-treated C3 KO mice. Urd and AEtLP treatment improved the histological structure, junctional complexes of the intestinal epithelial barrier (IEB), mucin secretion ability, and water retention capacity. Also, an improvement in the composition of neuronal cells, the regulation of excitatory function mediated via the 5-hydroxytryptamine (5-HT) receptors and muscarinic acetylcholine receptors (mAChRs), and the regulation of the inhibitory function mediated via the neuronal nitric oxide synthase (nNOS) and inducible NOS (iNOS) were detected in the enteric nervous system (ENS) of Urd- and AEtLP-treated C3 KO mice. Therefore, the results of the present study suggest that C3-deficiency-induced constipation can improve with treatment with Urd and AEtLP via the regulation of the mucin secretion ability, water retention capacity, and ENS function.

Dysbiosis of Fecal Microbiota in Tg2576 Mice for Alzheimer's Disease during Pathological Constipation

Tg2576 transgenic mice for Alzheimer's disease (AD) exhibited significant phenotypes for neuropathological constipation, but no research has been conducted on the association of the fecal microbiota with dysbiosis. The correlation between fecal microbiota composition and neuropathological constipation in Tg2576 mice was investigated by examining the profile of fecal microbiota and fecal microbiota transplantation (FMT) in 9-10-month-old Tg2576 mice with the AD phenotypes and constipation. Several constipation phenotypes, including stool parameters, colon length, and histopathological structures, were observed prominently in Tg2576 mice compared to the wild-type (WT) mice. The fecal microbiota of Tg2576 mice showed decreases in Bacteroidetes and increases in the Firmicutes and Proteobacteria populations at the phylum level. The FMT study showed that stool parameters, including weight, water content, and morphology, decreased remarkably in the FMT group transplanted with a fecal suspension of Tg2576 mice (TgFMT) compared to the FMT group transplanted with a fecal suspension of WT mice (WFMT). The distribution of myenteric neurons and the interstitial cells of Cajal (ICC), as well as the enteric nervous system (ENS) function, remained lower in the TgFMT group. These results suggest that the neuropathological constipation phenotypes of Tg2576 mice may be tightly linked to the dysbiosis of the fecal microbiota.

[Prevalence and risk factors of coronary artery calcification on lung cancer screening with low-dose CT]

Objective: To investigate the prevalence and risk factors of coronary artery calcification (CAC) on lung cancer screening with low-dose computed tomography (LDCT). Methods: A total of 4 989 asymptomatic subjects (2 542 males and 2 447 females) who underwent LDCT lung cancer screening were recruited at Cancer Hospital, Chinese Academy of Medical Sciences from 2014 to 2017. The visual scoring method was used to assess coronary artery calcification score. χ(2) test or independent t-test was used to compare the difference of CAC positive rate among different groups. Multivariate logistic regression was used to analyze risk factors associated with CAC in the study. Results: Of the 4 989 asymptomatic subjects, CAC occurred in 1 018 cases. The positive rate was 20.4%, of which mild, moderate and severe calcification accounted for 86.3%, 11.4% and 2.3%, respectively. Gender, age, BMI, education level, occupation, smoking history, diabetes, hypertension and hyperlipidemia had statistically significant differences in CAC positive rates among groups. Multivariate logistic regression analysis showed that gender, age, diabetes, hypertension, hyperlipidemia and smoking history were risk factors for CAC. Age, diabetes, hypertension and smoking history were statistically significant risk factors between the mild and moderate CAC group. A total of 1 730 coronary arteries in 1 018 CAC positive cases had calcification, CAC positive rate of left anterior descending was the highest(51.3%); 568 cases (55.8%) were single vessel calcification, 450 cases (44.2%) were multiple vessel calcification. Conclusions: LDCT can be used for the 'one-stop' early detection of lung cancer and coronary atherosclerosis. Gender, age, diabetes, hypertension, hyperlipidemia and smoking are related risk factors for coronary atherosclerosis.

[Prediction of trends for fine-scale spread of Oncomelania hupensis in Shanghai Municipality based on supervised machine learning models]

OBJECTIVE

To predict the trends for fine-scale spread of Oncomelania hupensis based on supervised machine learning models in Shanghai Municipality, so as to provide insights into precision O. hupensis snail control.

METHODS

Based on 2016 O. hupensis snail survey data in Shanghai Municipality and climatic, geographical, vegetation and socioeconomic data relating to O. hupensis snail distribution, seven supervised machine learning models were created to predict the risk of snail spread in Shanghai, including decision tree, random forest, generalized boosted model, support vector machine, naive Bayes, k-nearest neighbor and C5.0. The performance of seven models for predicting snail spread was evaluated with the area under the receiver operating characteristic curve (AUC), F1-score and accuracy, and optimal models were selected to identify the environmental variables affecting snail spread and predict the areas at risk of snail spread in Shanghai Municipality.

RESULTS

Seven supervised machine learning models were successfully created to predict the risk of snail spread in Shanghai Municipality, and random forest (AUC = 0.901, F1-score = 0.840, ACC = 0.797) and generalized boosted model (AUC= 0.889, F1-score = 0.869, ACC = 0.835) showed higher predictive performance than other models. Random forest analysis showed that the three most important climatic variables contributing to snail spread in Shanghai included aridity (11.87%), ≥ 0 °C annual accumulated temperature (10.19%), moisture index (10.18%) and average annual precipitation (9.86%), the two most important vegetation variables included the vegetation index of the first quarter (8.30%) and vegetation index of the second quarter (7.69%). Snails were more likely to spread at aridity of < 0.87, ≥ 0 °C annual accumulated temperature of 5 550 to 5 675 °C, moisture index of > 39% and average annual precipitation of > 1 180 mm, and with the vegetation index of the first quarter of > 0.4 and the vegetation index of the first quarter of > 0.6. According to the water resource developments and township administrative maps, the areas at risk of snail spread were mainly predicted in 10 townships/subdistricts, covering the Xipian, Dongpian and Tainan sections of southern Shanghai.

CONCLUSIONS

Supervised machine learning models are effective to predict the risk of fine-scale O. hupensis snail spread and identify the environmental determinants relating to snail spread. The areas at risk of O. hupensis snail spread are mainly located in southwestern Songjiang District, northwestern Jinshan District and southeastern Qingpu District of Shanghai Municipality.

[Potential transmission risk of key parasitic diseases and responses to the risk during the construction of an ecological city in Shanghai Municipality]

A blueprint on Shanghai's ecological space design between 2021 and 2035 was released in 2021, aiming to build an ecological city and improve the development of ecological civilization. The transmission of parasitic diseases is strongly associated with climate and ecological environments. Currently, the prevalence of parasitic diseases has been maintained at extremely low-transmission levels, and there are almost no local cases; however, the alteration of ecological environments may results in a potential transmission risk of parasitic diseases. Hereby, the current status of key parasitic diseases in Shanghai Municipality was described, and the potential transmission risk of parasitic diseases and responses to this risk were analyzed during the construction of an ecological city in Shanghai Municipality. In addition, the suggestions pertaining to surveillance and management of parasitic diseases were proposed during the mid- and long-term construction of an ecological city in Shanghai Municipality.

[Prevalence of Clonorchis sinensis infections in freshwater fish in mainland China: A meta-analysis]

OBJECTIVE

To understand the real prevalence of Clonorchis sinensis infections in the freshwater fish in mainland China, so as to provide insights into clonorchiasis control and detection of freshwater fish.

METHODS

All literatures reporting the prevalence of C. sinensis infections in the freshwater fish, the second intermediate host of the parasite, were jointly retrieved in Chinese and English electronic databases from January 1, 2010 to December 31, 2020, including Wanfang Data, CNKI, PubMed, Web of Science, Embase and Cochrane Library. All studies were screened based on inclusion and exclusion criteria, and the quality of all enrolled literatures was evaluated. The pooled prevalence of C. sinensis infections in freshwater fish and its 95% confidence interval (CI) were estimated using the software Stata version 15.0, and subgroup analyses were performed to investigate the region-, season- and sample source-specific pooled prevalence of C. sinensis infections in freshwater fish. In addition, the sensitivity and publication bias of all included studies were analyzed.

RESULTS

A total of 40 eligible literatures were included in this study, including 37 Chinese literatures and 3 English literatures, and there were 10 high-quality literatures, 27 moderate-quality literatures and 3 low-quality literatures. A total of 53 species containing 37 959 freshwater fish were reported in these 40 studies, and 73.58% (39/53) of freshwater fish species were identified with C. sinensis infections. Meta-analysis showed 23.5% [95% CI: (0.19, 0.28)] pooled prevalence of C. sinensis infections in freshwater fish in mainland China, and subgroup analyses higher prevalence of C. sinensis infections in freshwater fish in northeastern China [35.7%, 95% CI: (0.22, 0.50)] than in central [25.9%, 95% CI: (0.04, 0.48)] and southern China [20.6%, 95% CI: (0.09, 0.32)], higher prevalence of C. sinensis infections in freshwater fish sampled in spring [44.1%, 95% CI: (0.35, 0.53)] than in autumn [6.7%, 95% CI: (0.05, 0.08)] and summer [3.3%, 95% CI: (-0.01, 0.07)], and higher prevalence of C. sinensis infections in freshwater fish sampled from natural water [25.2%, 95% CI: (0.17, 0.33)] than from retail trades [22.2%, 95% CI: (0.17, 0.28)] and breeding chain [12.3%, 95% CI: (0.03, 0.22)]. However, all included studies had a publication bias with a low sensitivity.

CONCLUSIONS

The prevalence of C. sinensis infections is high in freshwater fish in mainland China, and there are still challenges for clonorchiasis control. Reinforcement of health education, diagnostics development and food safety supervision is recommended in future clonorchiasis control programs.

Three-Dimensional Dirac Phonons with Inversion Symmetry

Dirac semimetals associated with bulk Dirac fermions are well known in topological electronic systems. In sharp contrast, three-dimensional (3D) Dirac phonons in crystalline solids are still unavailable. Here we perform symmetry arguments and first-principles calculations to systematically investigate 3D Dirac phonons in all space groups with inversion symmetry. The results show that there are two categories of 3D Dirac phonons depending on their protection mechanisms and positions in momentum space. The first category originates from the four-dimensional irreducible representations at the high symmetry points. The second category arises from the phonon branch inversion, and the symmetry guarantees Dirac points to be located along the high symmetry lines. Furthermore, we reveal that nonsymmorphic symmetries and the combination of inversion and time-reversal symmetries play essential roles in the emergence of 3D Dirac phonons. Our work not only offers a comprehensive understanding of 3D Dirac phonons but also provides significant guidance for exploring Dirac bosons in both phononic and photonic systems.

[Expert consensus on the strategy and measures to interrupt the transmission of schistosomiasis in China]

Since 2015 when the transmission of schistosomiasis was controlled in China, the country has been moving towards elimination of schistosomiasis, with the surveillance-response as the main interventions for schistosomiasis control. During the period of the 13th Five-Year Plan, the transmission of schistosomiasis had been interrupted in four provinces of Sichuan, Jiangsu, Yunnan and Hubei and the prevalence of schistosomiasis has been at the historically lowest level in China. As a consequence, the goal set in The 13th Five-Year National Schistosomiasis Control Program in China is almost achieved. However, there are multiple challenges during the stage moving towards elimination of schistosomiasis in China, including the widespread distribution of intermediate host snails and complicated snail habitats, many types of sources of Schistosoma japonicum infections and difficulty in management of bovines and sheep, unmet requirements for the current schistosomiasis control program with the currently available tools, and vulnerable control achievements. During the 14th Five-Year period, it is crucial to consolidate the schistosomiasis control achievements and gradually solve the above difficulties, and critical to provide the basis for achieving the ultimate goal of elimination of schistosomiasis in China. Based on the past experiences from the national schistosomiasis control program and the challenges for schistosomiasis elimination in China, an expert consensus has been reached pertaining to the objectives, control strategy and measures for The 14th Five-Year National Schistosomiasis Control Program in China, so as to provide insights in to the development of The 14th Five-Year National Schistosomiasis Control Program in China.

Two-Dimensional Dirac Semimetals without Inversion Symmetry

Realizing stable two-dimensional (2D) Dirac points against spin-orbit coupling (SOC) has attracted much attention because it provides a platform to study the unique transport properties. In previous work, Young and Kane [Phys. Rev. Lett. 115, 126803 (2015)PRLTAO0031-900710.1103/PhysRevLett.115.126803 proposed stable 2D Dirac points with SOC, in which the Berry curvature and edge states vanish due to the coexistence of inversion and time-reversal symmetries. Herein, using the tight-binding model and k·p effective Hamiltonian, we present that 2D Dirac points can survive in the presence of SOC without inversion symmetry. Such 2D Dirac semimetals possess nonzero Berry curvature near the crossing nodes, and two edge states are terminated at one pair of Dirac points. In addition, according to symmetry arguments and high-throughput first-principles calculations, we identify a family of ideal 2D Dirac semimetals, which has nonzero Berry curvature in the vicinity of Dirac points and visible edge states, thus facilitating the experimental observations. Our work shows that 2D Dirac points can emerge without inversion symmetry, which not only enriches the classification of 2D topological semimetals but also provides a promising avenue to observe exotic transport phenomena beyond graphene, e.g., nonlinear Hall effect.

Robust Twin Pairs of Weyl Fermions in Ferromagnetic Oxides

The ferromagnetic Weyl semimetals with inversion symmetry usually possess odd pairs of Weyl fermions. Here, we present an inversion eigenvalue argument to dictate the existence of even pairs of ferromagnetic Weyl fermions. We show, by a combination of first-principles calculations and symmetry analyses, that this exotic topological feature can be verified in ferromagnetic oxides in different space groups. In particular, a realistic candidate, i.e., hollandite RbCr_{4}O_{8} with a high Curie temperature (∼295  K), hosts intriguing twin pairs of Weyl fermions, which are robustly stable against perturbations. Moreover, our effective model and symmetry analysis show that the twin pairs of Weyl fermions originate from a mirrored nodal ring pair. The nontrivial surface states and Fermi arcs of RbCr_{4}O_{8} are clearly visible, further revealing the topological features. This work strengthens the understanding of the parity analysis in exploring ferromagnetic topological materials with unconventional fermionic excitations.

[The volume and mass growth of persisted pulmonary nodules detected in low-dose CT screening and its influence factors]

Objective: To evaluate the changes of volume and mass of pulmonary nodules which were detected in low-dose computed tomography (LDCT) screening, and to analyze the influencing factors. Methods: This retrospective study analyzed the CT images of the participants who underwent at least two chest LDCT scanning from March 2009 to December 2015 in National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College. The inclusion criteria was the nodule diameter ≥6 mm; the volume growth was defined as ≥20%. Fifty-one pulmonary nodules (PNs) were selected among 51 enrolled participants (26 men and 25 women). According to characteristic of nodule and risk stratification of participant, the nodules were classified into different groups (10 non-solid nodules, 17 part-solid nodules and 24 solid nodules; 14 PNs in high-risk group, 12 PNs in moderate-risk group and 25 PNs in low-risk group). The Lung-VCAR software was used to measure the diameter and volume of the PNs, and all nodules were calculated for the volume doubling time (VDT) and mass doubling time (MDT). Results: Among the 51 PNs, the diameter of 33 nodules increased more than 1.5 mm while 18 nodules increased less than 1.5 mm. The median VDT of part-solid nodules was 364 days, which was shorter than that of non-solid nodules and solid nodules (761 and 819 days, respectively), the differences were statistically significant (both P<0.05). The median MDT of part-solid nodules was 351 days, which was lower than that of non-solid nodules and solid nodules (772 days and 840 days, respectively). The difference was statistically significant (P<0.05). The median VDT and MDT of the pulmonary nodules in the high-risk group were 181 days and 256 days, respectively, which were lower than those in the low risk group (1 037 days and 1 035 days, respectively). VDT has good correlation with MDT (r=0.909, P<0.001). Conclusions: Both the characteristic of PNs and the risk status of the participants could affect the growth of nodules in LDCT screening. The part-solid nodules and high-risk group nodules grew relatively faster, which should be closely focused on. Compared with the two-dimensional diameter, the three-dimensional quantitative indicators (VDT and MDT) were more sensitive for nodule growth. The mass changes of part-solid nodules were earlier than that of volume.

Polymorphisms of TGFB1, TLE4 and MUC22 are associated with childhood asthma in Chinese population

OBJECTIVE

To investigate whether the genetic variants of TGFB1, TLE4, MUC22 and IKZF3 are associated with the development of asthma in Chinese children.

METHODS

572 adolescent asthma patients and 590 age-matched healthy controls were included in this study. A total of four SNPs were genotyped, including rs2241715 of TGFB1, rs2378383 of TLE4, rs2523924 of MUC22, and rs907092 of IKZF3. Allele frequencies of the patients and the control group were compared by the Chi-square test. The Student t test was used to analyse the relationship between genotypes and clinical feature of the patients.

RESULTS

Patients were found to have significantly different frequencies of allele A of rs2241715, allele G of rs2378383 and allele A of rs2523924 as compared with the controls (40.4% vs. 45.9%, p=0.01 for rs2241715; 17.2% vs. 13.4%, p=0.01 for rs2378383; 15.3% vs. 11.9%, p=0.02 for rs2523924). For patients with severe asthma, those with genotype AA/AG of rs2241715 had remarkably higher FEV1% as compared with those with genotype GG (59.1±4.3% vs. 55.4±3.7%, p<0.001). Moreover, those with genotype GG/GA of rs2378383 had remarkably lower FEV1% as compared with those with genotype AA (54.6±2.9% vs. 58.6±4.1%, p<0.001).

CONCLUSIONS

Genes TGFB1, TLE4 and MUC22 are associated with the risk of childhood asthma in Chinese population. Our results associating TGFB1 and TLE4 with clinical features of asthma suggest potential application of these parameters in the management of asthma children.

Development and evaluation of the automated risk assessment system for multidrug-resistant organisms (autoRAS-MDRO)

BACKGROUND

A high proportion of infections acquired in hospitals are caused by multidrug-resistant organisms (MDROs). The priority in MDRO prevention is to detect high-risk patients and implement preventive intervention as soon as possible.

AIM

To develop an automated risk assessment system for MDROs (autoRAS-MDRO) to screen for patients at MDRO infection risk and evaluate the predictive validity of the autoRAS-MDRO.

METHODS

Data for 4200 variables were extracted from the electronic health records (EHRs) for constructing the MDRO risk-scoring algorithm, which was based on a logistic regression model. The autoRAS-MDRO was designed such that the MDRO risk classification (high, moderate, low risk) could be automatically displayed on the nursing Kardex screen in the EHRs system. For the development of the MDRO risk-scoring algorithm, 1000 patients with MDROs and 4000 patients without MDROs were selected; similarly, for the evaluation, 2173 and 8692 patients with and without MDROs, respectively, were selected.

FINDINGS

The predictive validity of the autoRAS-MDRO was as follows: (i) at the 6-month evaluation: sensitivity, 81%; specificity, 79%; positive predictive value (PPV), 49%; negative predictive value (NPV), 94%; and Youden index, 0.60; (ii) at the 12-month evaluation: sensitivity 79%, specificity 78%, PPV 47%, NPV 94%, and Youden index, 0.57.

CONCLUSION

The autoRAS-MDRO had moderate predictive validity. It could be useful in redirecting nurses' time and efforts required for MDRO risk assessment and implementation of infection control measures, and in reducing the incidence of MDRO infection in hospitals, thereby contributing to patient safety.

[Significance of v-raf murine sarcoma viral oncogene homologue B1 in rheumatoid arthritis]

OBJECTIVE

To detect serum v-raf murine sarcoma viral oncogene homologue B1 (BRAF) protein levels and to investigate their clinical significance in rheumatoid arthritis (RA) patients.

METHODS

Serum samples were obtained from 78 RA patients, 32 osteoarthritis (OA) patients, 16 systemic lupus erythematosus (SLE) patients, 16 gout patients, 16 ankylosing spondylitis (AS) patients, 16 Sjogren syndrome (SS) patients and 30 healthy controls. BRAF protein in the sera was examined by enzyme-linked immunosorbent assay (ELISA). The associations between BRAF levels and the clinical features including age, sex, disease duration, swelling joints, tenderness joints, duration of moning stiffness, joint deformity, visual assessment scale (VAS) and extra articular manifestations and laboratory parameters including erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF), disease activity score in 28 joints (DAS28), anti-cyclic citrullinated peptide (CCP) antibody, antikeratin antibody, antnuclear antibody (ANA), immunoglobulin and cytokines, such as TNF-α, IL-1β, IL-6 and IL-17A in RA patients were evaluated. Data analyses were performed by using SPSS 19.0 program.

RESULTS

The serum BRAF protein levels in the RA patients were significantly higher than those of other rheumatic diseases groups including OA, SLE, AS, SS, gout patients and healthy controls, the P value was 0.002, <0.001, <0.001, <0.001, 0.001 and <0.001 respectively. The level of serum BRAF protein in the RA patients showed a positive correlation with the rheumatoid factor (P=0.009) and IgA levels (P=0.006), but no correlation with clinical features, such as age and duration or other laboratory parameters, including CRP, ESR, anti-CCP antibody, IgM, IgG, TNF-α, IL-1β, IL-6 and IL-17A. The RA patients were further divided into normal levels of BRAF protein group and elevated levels of BRAF protein group. Compared with the clinical features and laboratory indexes of normal and elevated levels of BRAF protein groups in the RA patients, there was no significant difference between the two groups in age, duration, DAS28, CRP, ESR, RF, anti-CCP, IgA, IgG, IgM, TNF-α or IL-6.

CONCLUSION

The elevated level of BRAF protein in the RA patients showed that BRAF might play a role in the pathogenesis of RA. Further researches on BRAF gene expression may help to clarify the role of BRAF in RA.

Spinal intraosseous arteriovenous fistula in the fractured vertebral body

A 68-year-old woman presenting with progressive paraparesis was diagnosed with an AVF involving a previously fractured L1 vertebral body on which feeders from multiple segmental arteries converged. The most distinctive feature in our patient was that the fistula was located in the vertebral body. Transarterial embolization of the segmental arteries with coils and glue resulted in total obliteration of the fistula, which in turn resulted in symptom improvement.

PAC1 is a direct transcription target of E2F-1 in apoptotic signaling

E2F-1 controls multiple cellular activities through transcriptional regulation of its target genes. As a mediator of cell death, E2F-1 can eliminate latent neoplastic cells through apoptosis. However, the mechanism by which E2F-1 mediates cancer cell killing is largely unknown. In this paper, we report that phosphatase of activated cells 1 (PAC1) phosphatase is a direct transcription target of E2F-1 in signaling apoptosis. We show that ectopic E2F-1 increases expression of PAC1 at both transcriptional and translational levels in breast cancer cells. E2F-1 physically interacts with the promoter of PAC1, binds to its consensus sequence in the promoter and transactivates the PAC1 promoter. E2F-1 suppresses extracellular signal-regulated kinase (ERK) phosphorylation through PAC1 and causes cancer cell death by apoptosis following treatment with a chemotherapeutic agent N-4-hydroxyphenylretinamide (4-HPR). Furthermore, ectopic PAC1 inhibits ERK phosphorylation and mediates cell killing. Moreover, endogenous E2F-1 upregulates PAC1 and suppresses ERK activity, leading to cell death in response to 4-HPR. These results reveal a crucial role of PAC1 in E2F-1-directed apoptosis. Our study demonstrates that E2F-1 mediates apoptosis through transcriptional regulation of PAC1 and subsequent suppression of the ERK signaling. Our findings establish a functional link between E2F-1 and mitogen-activated protein kinases. The E2F-1-PAC1 cascade in cancer cell killing may provide a molecular basis for cancer therapeutic intervention.

pp60c-src activation in lung adenocarcinoma

Nine src family members are known including c-Src, c-Yes, c-Lck, c-Fyn, c-Hck, c-Lyn, c-Blk, c-Fgr and c-Yrk. They encode proteins with molecular weights of 55-62 kilodaltons (kDa), which are either cytoplasmic or membrane-associated protein tyrosine kinases. A close correlation exists between an elevated pp60c-src tyrosine kinase activity and cell transformation. However, the level of activation of pp60c-src in non-small cell lung cancers (NSCLC) remains obscure. The aim of this study was to examine the level of activity of pp60c-src in NSCLC. pp60c-src expression and in vitro protein tyrosine kinase activity in lung cancer tissue samples were measured by western blotting and in vitro kinase assays and compared with those in the surrounding non-tumour lung tissue from the same patient. pp60c-src phosphorylation was assessed by two-dimensional tryptic phosphopeptide mapping. The kinase activity of pp60c-src was significantly activated in NSCLC, especially in adenocarcinomas. In addition, the pp60c-src kinase activity increased with the size of the adenocarcinoma. Two-dimensional tryptic phosphopeptide mapping showed dephosphorylation of pp60c-src at Tyr 530 in adenocarcinomas. The proto-oncogene product, pp60c-src, was activated in NSCLC, especially in adenocarcinomas, in part through the dephosphorylation of Tyr 530. Our results suggest that activation of pp60c-src might play an important role in the progression of lung adenocarcinomas.

Reconstruction of basement membrane in skin equivalent; role of laminin-1

To reconstruct the basement membrane in a skin equivalent, the epidermodermal interface was coated with porcine type IV collagen and mouse laminin-1 at various ratios before keratinocyte seeding. Laminin-1, a component of the basement membrane, induced massive infiltration of keratinocytes into the dermal equivalent, while type IV collagen induced discrete demarcation between dermal and epidermal compartments without any infiltrating cells. Immunohistochemical staining indicated that the laminin-induced infiltrating cells expressed endogenous type IV collagens at the cell periphery, which were not incorporated into the basement membrane structure. The infiltrating cells did not express fibronectin receptor alpha5beta1 integrin but showed MMP-9 secretion and cell surface associated MMP-2. However, when laminin-1 was preincubated with type IV collagen, laminin-1-induced keratinocyte infiltration as well as MMP-9 induction were almost completely suppressed to basal levels. Therefore, replenishment of the type IV collagen lattice seemed to cause laminin-stimulated cells to anchor to the lattice, in a similar manner to the basal cells on the basement membrane of normal skin. Our study suggests that the molar ratio of basement membrane components may determine the behavior of basal cells within the wound healing microenvironment, which is probably regulated either by extracellular matrix deposition or degradation.

[Effect of sodium ferulate on leucocyte spontaneous activation and surface adhesion molecule expression in arteriosclerosis obliterans patients]

OBJECTIVE

To explore the effect of sodium ferulate (SF) on leucocyte spontaneous activation rate (LSAR) and the surface expression of adhesion molecule (SEAM) in patients with arteriosclerosis obliterans (ASO).

METHODS

Forty-two patients with ASO were treated by SF, LSAR and SEAM in them were determined qualitatively before and after SF treatment, as well as in 36 healthy subjects for control.

RESULTS

Therapeutic effect of SF in the treated 42 patients was short-term cured in 17 cases (40.5%), markedly effective in 21 (50%), effective in 2 (4.8%), ineffective in 2(4.8%), and the total effective rate being 95.2%. LSAR and SEAM in ASO patients before treatment was 14.84 +/- 7.54% and 47.94 +/- 13.48% respectively, which was obviously higher than 4.96 +/- 2.04% and 24.12 +/- 9.35% in healthy subjects (P < 0.01) respectively, but markedly reduced to 8.19 +/- 4.09% and 28.63 +/- 7.91% after SF treatment (P < 0.01).

CONCLUSION

SF could not only obviously lower both LSAR and SEAM but also exert a good therapeutic effect on patients with ASO.

Calcipotriol inhibits autocrine phosphorylation of EGF receptor in a calcium-dependent manner, a possible mechanism for its inhibition of cell proliferation and stimulation of cell differentiation

We report in this study that proliferation inhibition of SCC13 cells by calcipotriol was possibly mediated by its inhibitory effect on autocrine activation of EGF receptor. Based on MTT assay, PCNA staining, DAPI staining, and involucrin immunocytochemical staining, we showed that calcipotriol inhibited cell growth and stimulated differentiation but did not induce apoptosis. Western blot analysis of concanavalin-A-bound fraction demonstrated that calcipotriol specifically dephosphorylated 170- and 66-kDa polypeptides from 8 h posttreatment and complete dephosphorylation was observed at 12 h posttreatment. The 170- and 66-kDa polypeptides were confirmed as EGF receptor and Shc, respectively. Calcipotriol-mediated EGF receptor dephosphorylation required the presence of extracellular calcium. Similar kinetics of the dephosphorylation was also observed in HaCaT cells cultured in medium of high calcium concentration. By BrdU labeling, we also showed calcium dependency of calcipotriol for the inhibition of cell proliferation. Therefore, EGF receptor deactivation by calcipotriol might be a mechanism of action for the inhibition of cell proliferation and the stimulation of differentiation in SCC13 cell and HaCaT cells.

Targeting Src homology 2 domain-containing tyrosine phosphatase (SHP-1) into lipid rafts inhibits CD3-induced T cell activation

To study the mechanism by which protein tyrosine phosphatases (PTPs) regulate CD3-induced tyrosine phosphorylation, we investigated the distribution of PTPs in subdomains of plasma membrane. We report here that the bulk PTP activity associated with T cell membrane is present outside the lipid rafts, as determined by sucrose density gradient sedimentation. In Jurkat T cells, approximately 5--10% of Src homology 2 domain-containing tyrosine phosphatase (SHP-1) is constitutively associated with plasma membrane, and nearly 50% of SHP-2 is translocated to plasma membrane after vanadate treatment. Similar to transmembrane PTP, CD45, the membrane-associated populations of SHP-1 and SHP-2 are essentially excluded from lipid rafts, where other signaling molecules such as Lck, linker for activation of T cells, and CD3 zeta are enriched. We further demonstrated that CD3-induced tyrosine phosphorylation of these substrates is largely restricted to lipid rafts, unless PTPs are inhibited. It suggests that a restricted partition of PTPs among membrane subdomains may regulate protein tyrosine phosphorylation in T cell membrane. To test this hypothesis, we targeted SHP-1 into lipid rafts by using the N-terminal region of Lck (residues 1--14). The results indicate that the expression of Lck/SHP-1 chimera inside lipid rafts profoundly inhibits CD3-induced tyrosine phosphorylation of CD3 zeta/epsilon, IL-2 generation, and nuclear mobilization of NF-AT. Collectively, these results suggest that the exclusion of PTPs from lipid rafts may be a mechanism that potentiates TCR/CD3 activation.

[The inhibitory effect of asODNs on the invasion of colorectal cancer cell line CCL229]

To study the inhibitory effect of antisense oligodeoxynucleotide (asODNs) on colrectal cancer cell line CCL229 invasion in vitro. A 15-mer asODNs targeted against the translation start site of UPAR (urokinase-type plasminogen activator receptor) mRNA were introduced into CCL229 cells by lipid-mediated DNA-transfection and the variation of the levels of uPAR mRNA, uPAR antigen expression of the levels of uPAR mRNA, uPAR antigen expression on the cell sruface and invasion properties were observed by reverse transcription-polymerase chain reaction (RT-PCR), flowcytometry(FCM) and aminion invasion assay, the morphological feature of the cell after asODNs treatment was observed by scanning electron microscope(SEM). The results indicate (1) the uPAR/beta-actin ratio was 0.44 +/- 0.02 for the asODNs treated cells, which is significantly lower compared with the control and rONDs treated cells (0.81 +/- 0.01 and 0.750 +/- 0.13 respectively, P < 0.01), (2) the mean fluorescence index of uPAR combined with uPA and the whole uPAR on surface were 0.20 +/- 0.07 and 0.59 +/- 0.09 respectively for asODNs treated cells, which is significantly lower compared with control cells (0.72 +/- 0.12 and 2.21 +/- 0.36 respectively, P < 0.05, P < 0.01); (3) the number of cells migrated the aminion (25 +/- 4, 44 +/- 5 for the control cells) obviously decreased after a-sODNs treatment, (12 +/- 2, 20 +/- 3, P < 0.05); (4) the filopodia and microspikes on the CCL 229 cell surface were decreased after asODNs treatment. The conclusion is that the expression of uPAR on the surface of CCL229 cell surface is responsible for invasity; the inhibitory effect of uPAR as ODNs were highly significant and this method may be of potential clinical interest in gene therapy of cancer.

Argatroban, a thrombin inhibitor, decreased mortality after 10 min of forebrain ischemia in the gerbil

We investigated whether anticoagulant therapy with heparin or a selective thrombin inhibitor, argatroban, may ameliorate the postischemic cerebral circulation and attenuate mortality after 10 min of forebrain ischemia. Postischemic subcutaneous injection of argatroban (5 mg/kg) significantly attenuated mortality (9.1%) compared with non-treatment (45.5%) during 14 days' observation period. This effect coincided with: (1) increased cortical CBF after reperfusion; (2) attenuation of brain edema; and (3) less severe cell damages in the cerebral cortex. In contrast, nine of the 22 gerbils treated with heparin (830 IU/kg) were found dead on the next day due to massive bleeding in the surgical wound and 13 bleeding-avoided gerbils did not show significant amelioration in mortality (30.8%). These findings suggest that argatroban is an effective anticoagulant for prevention of cell damage after a relatively long forebrain ischemia.

Cytosolic tyrosine dephosphorylation of STAT5. Potential role of SHP-2 in STAT5 regulation

STAT5, a member of the signal transducers and activators of transcription (STATs), is important in modulating T cell functions through interleukin-2 (IL-2) receptors. Like other STAT proteins, STAT5 undergoes a rapid activation and inactivation cycle upon cytokine stimulation. Tyrosine phosphorylation and dephosphorylation are critical in regulating STAT5 activity. A number of protein tyrosine kinases have been shown to phosphorylate STAT5; however, the phosphatases responsible for STAT5 dephosphorylation remain unidentified. Using CTLL-20 as a model system, we provide evidence that tyrosine dephosphorylation of STAT5 subsequent to IL-2-induced phosphorylation occurs in the absence of STAT5 nuclear translocation and new protein synthesis. Nevertheless, down-regulation of the upstream Janus kinase activity during the deactivation cycle of IL-2-induced signaling does involve new protein synthesis. These findings point to the constitutive presence of STAT5 tyrosine phosphatase activity in the cytosolic compartment. We further demonstrate that SHP-2, but not SHP-1, directly dephosphorylates STAT5 in an in vitro tyrosine phosphatase assay with purified proteins. Furthermore, tyrosine-phosphorylated STAT5 associates with the substrate-trapping mutant (Cys --> Ser) of SHP-2 but not SHP-1. These results suggest a potential role for cytoplasmic protein-tyrosine phosphatases in directly dephosphorylating STAT proteins and in maintaining a basal steady state level of STAT activity.

Human 70-kDa SHP-1L differs from 68-kDa SHP-1 in its C-terminal structure and catalytic activity

The tyrosine phosphatase SHP-1 functions as a negative regulator in hematopoietic cell development, proliferation, and receptor-mediated cellular activation. In Jurkat T cells, a major 68-kDa band and a minor 70-kDa band were immunoprecipitated by a monoclonal antibody against the SHP-1 protein-tyrosine phosphatase domain, while an antibody against the SHP-1 C-terminal 19 amino acids recognized only the 68-kDa SHP-1. The SDS-gel-purified 70-kDa protein was subjected to tryptic mapping and microsequencing, which was followed by molecular cloning. It revealed that the 70-kDa protein, termed SHP-1L, is a C-terminal alternatively spliced form of SHP-1. SHP-1L is 29 amino acids longer than SHP-1, and its 66 C-terminal amino acids are different from SHP-1. The C terminus of SHP-1L contains a proline-rich motif PVPGPPVLSP, a potential Src homology 3 domain-binding site. In contrast to SHP-1, tyrosine phosphorylation of SHP-1L is not detected upon stimulation in Jurkat T cells. This is apparently due to the lack of a single in vivo tyrosine phosphorylation site, which only exists in the C terminus of SHP-1 (Y564). COS cell-expressed glutathione S-transferase-SHP-1L can dephosphorylate tyrosine-phosphorylated ZAP70. At pH 7.4, SHP-1L was shown to be more active than SHP-1 in the dephosphorylation of ZAP70. At pH 5.4, SHP-1L and SHP-1 exhibited similar catalytic activity. It is likely that these two isoforms play different roles in the regulation of hematopoietic cell signal transduction.

Diagnostic p53 expression in gastric endoscopic mucosal resection

Endoscopic mucosal resection (EMR) has been standardized for the treatment of intestinal type of intramucosal gastric carcinomas, and careful histological examination of the resected specimen is important for further treatment. To evaluate the diagnostic utility of p53 expression in gastric EMR samples, using immunohistochemical staining, we examined 24 gastric carcinomas (22 intestinal types and two diffuse types) and 20 adenomas removed by EMR. Intestinal type of adenocarcinomas revealed strong p53 expression in 13 cases (59%), weak in four cases (18%), and negative in five cases (23%). Resection margins of 11 carcinomas were involved in the carcinoma cells, which showed the same p53 expression pattern with main carcinoma cells. Squeezed carcinoma cells, remaining in resection margins, were definitely identified by strong p53 expression in seven cases of which the main tumor strongly expressed p53. Microscopic in situ carcinoma could be easily detected in p53 immunostaining. Multifocal involvement and submucosal invasion of carcinomas could be demarcated easily and definitely by strong p53 expression of carcinoma cells. All adenomas showed diffuse weak p53 expression. The difference of p53 expression (p< 0.001) could be used as a differential diagnosis between adenomas and carcinomas. According to these results, we propose that for careful histological examination in hospital diagnosis, both histological evaluation and p53 immunostaining are important diagnostic parameters in EMR samples of the intestinal type of gastric carcinomas.

Regulation of tyrosine phosphorylation in isolated T cell membrane by inhibition of protein tyrosine phosphatases

Jurkat T cells activated by the phosphotyrosine phosphatase inhibitors H2O2 or vanadate were found to have a similar pattern of tyrosine phosphorylation when compared with T cells stimulated by anti-CD3 Ab cross-linking, suggesting that protein tyrosine phosphatase (PTP) inhibitors affect the early steps of TCR signaling. To study the role of PTPs in the most proximal membrane events of tyrosine phosphorylation, subcellular fractions of T cells were treated with the PTP inhibitors in the presence of ATP. In the membrane fraction, tyrosine phosphorylation of Lck, Fyn, and CD3 zeta can be induced by PTP inhibitors, but not by anti-CD3. Detailed characterization of this cell-free system showed that the pattern and the order of induced tyrosine phosphorylation is similar to that induced in intact cells. Upon removal of the PTP inhibitor, the tyrosine-phosphorylated proteins, including Lck, Fyn, Syk, Zap70, and CD35 zeta are rapidly dephosphorylated. Preliminary characterizations indicate that a PTP distinct from CD45, SHP1, and SHP2 is present in T cell membranes and the inhibition of this yet unidentified PTP is most likely responsible for the Lck-dependent tyrosine phosphorylation triggered by PTP inhibitors.

Structural organization of the genes encoding human and murine FK506-binding protein (FKBP) 13 and comparison to FKBP1

FK506-binding protein (FKBP)12 and FKBP13 are members of a family of proteins which bind the immunosuppressant drugs, FK506 and rapamycin. FKBP12 and FKBP13 are encoded by distinct genes, designated FKBP1 and FKBP2, respectively. The structure of human FKBP1 was previously characterized. We now report the genomic structure of the human and murine FKBP2 genes. Comparison of FKBP1 and FKBP2 reveals significant homology and correlation of intron positions in the C-terminal region, suggesting that these genes may have evolved from a common ancestral gene.

Localization of the FK506-binding protein, FKBP 13, to the lumen of the endoplasmic reticulum

The function of the immunophilins, FKBP 12 and FKBP 13, which are binding proteins for the immunosuppressant drug FK506 and rapamycin, remains poorly defined, although it has been suggested that immunophilins and immunophilin-like proteins may play a role in protein sorting/folding and intracellular calcium ion regulation. As a first step towards understanding the function of FKBP 13, we studied its subcellular localization by immunoblotting of well-defined subcellular fractions from a canine pancreatic homogenate and immunocytochemical analysis of an overexpressed cloned cDNA for FKBP 13. Whereas FKBP 12 fractionated entirely into the cytosol, virtually all FKBP 13 was found in the rough microsomal fraction which consisted of highly purified rough endoplasmic reticulum (ER), along with several well-characterized ER markers [the immunoglobulin heavy-chain binding protein (BiP), grp 94 and ribophorin I]. Moreover, FKBP 13 co-banded with the ER markers on isopycnic sucrose gradients. By immunofluorescence, the overexpressed cDNA for FKBP 13 in Hela cells gave an ER-staining pattern highly similar to that of known ER proteins. Addition of the ligand FK506 did not appear to alter the distribution of FKBP 13. Separation of the ER luminal contents and membrane revealed FKBP 13 to be a luminal ER protein. Since the lumen of the ER is where the folding of membrane and secreted proteins occurs, as well as a major site of intracellular calcium storage, it seems possible that FKBP 13 may be involved in one of these functions.

The 25-kDa FK506-binding protein is localized in the nucleus and associates with casein kinase II and nucleolin

FK506-binding proteins (FKBPs) have been identified as the cellular receptors of the immunosuppressive drugs FK506 and rapamycin. Recently, we cloned a 25-kDa FKBP family member (FKBP25) and found that FKBP25 contains a nuclear localization sequence and several potential casein kinase II phosphorylation sites. It has been previously shown that phosphorylation of proteins by casein kinase II can enhance their nuclear localization. Here we demonstrate that FKBP25 is localized to the nucleus and that a glutathione S-transferase fusion protein of FKBP25 (GST-FKBP25) can be phosphorylated by casein kinase II. Also a stable FKBP25/casein kinase II complex was formed when the GST-FKBP25 fusion protein was incubated either with purified casein kinase II or with cell lysates. Furthermore, when GST-FKBP25 was incubated with nuclear lysates, nucleolin, a major nuclear substrate of casein kinase II, was found associated with the GST-FKBP25/casein kinase II complex. Casein kinase II phosphorylation of several cytosolic and nuclear substrates, including nucleolin, appears to be important for the regulation of cell growth. The interaction of FKBP25 with casein kinase II may regulate these functions.

Effects of cyclosporin A and FK506 on Fc epsilon receptor type I-initiated increases in cytokine mRNA in mouse bone marrow-derived progenitor mast cells: resistance to FK506 is associated with a deficiency in FK506-binding protein FKBP12

The inhibitory effects of cyclosporin A (CsA) and FK506 on Fc epsilon receptor type I-initiated increases in cytokine mRNA and the expression of their intracellular binding proteins were studied in interleukin 3 (IL-3)-dependent, mouse bone marrow-derived mast cells (BMMCs). In BMMCs sensitized with IgE anti-trinitrophenyl, CsA inhibited trinitrophenylated bovine serum albumin-induced increases in mRNA for IL-1 beta, tumor necrosis factor alpha (TNF-alpha), and IL-6 in a dose-related manner (IC50 values of 4, 65, and 130 nM, respectively). FK506 did not inhibit hapten-specific increases of mRNA for TNF-alpha or IL-6, and for IL-1 beta the IC50 was greater than 50-fold higher than that of CsA. Neither agent inhibited exocytosis of the endogenous secretory granule mediators beta-hexosaminidase and histamine at the IC50 values for inhibition of increases in cytokine mRNA. BMMCs expressed cyclophilin, and CsA inhibited the phosphatase activity of cellular calcineurin with an IC50 of approximately 8 nM. That CsA inhibited IL-1 beta mRNA accumulation in IgE-activated BMMCs with an IC50 similar to that for inhibition of calcineurin activity, whereas the IC50 values were approximately 20-fold higher for the inhibition of TNF-alpha and IL-6 mRNA, suggests that the induction of TNF-alpha and IL-6 is less dependent upon calcineurin activity than is the induction of IL-1 beta. BMMCs were deficient in the 12-kDa FK506-binding protein FKBP12, but not FKBP13, as assessed by RNA and protein blot analyses. FK506 did not inhibit calcineurin phosphatase activity in BMMCs, even at drug concentrations of 1000 nM. The resistance of BMMCs to inhibition of Fc epsilon receptor type I-mediated increases in cytokine mRNA by FK506 is most likely due to their deficiency of FKBP12 and the related inability to inhibit the activity of calcineurin.

Molecular cloning of a 25-kDa high affinity rapamycin binding protein, FKBP25

Two FK506 binding proteins of molecular mass 12 kDa (FKBP12) and 13 kDa (FKBP13) have been identified as common cellular receptors of the immunosuppressants FK506 and rapamycin. Here we report the molecular cloning and overexpression of a 25-kDa rapamycin and FK506 binding protein (termed FKBP25) with peptidylprolyl cis-trans-isomerase (PPIase) activity. The amino acid sequence, predicted from the FKBP25 cDNA, shares identity with FKBP12 (44%) and FKBP13 (47%) in the C-terminal 97 amino acids. Unlike either FKBP12 or FKBP13, the nucleotide sequence of FKBP25 contains a number of putative nuclear localization sequences. The PPIase activity of recombinant FKBP25 was comparable with that of FKBP12. The PPIase activity of FKBP25 was far more sensitive to inhibition by rapamycin (IC50 = 50 nM) than FK506 (IC50 = 400 nM). PPIase activity of 100 nM FKBP25 was almost completely inhibited by 150 nM rapamycin while only 90% inhibition was achieved by 4 microM FK506. These data demonstrate that FKBP25 has a higher affinity for rapamycin than for FK506 and suggest that this cellular receptor may be an important target molecule for immunosuppression by rapamycin.

Molecular cloning of a membrane-associated human FK506- and rapamycin-binding protein, FKBP-13

The 12-kDa FK506-binding protein (FKBP-12) is a cytosolic receptor for the immunosuppressants FK506 and rapamycin. Here we report the molecular cloning and subcellular localization of a 13-kDa FKBP (FKBP-13), which has a 21-amino acid signal peptide and appears to be membrane-associated. Although no internal hydrophobic region, and thus no transmembrane domain, is apparent within the 120 amino acids of mature FKBP-13, a potential endoplasmic reticulum retention sequence (Arg-Thr-Glu-Leu) is found at its C terminus. FKBP-13 has 51% nucleotide sequence identity and 43% amino acid sequence identity to FKBP-12; the N-terminal sequences are divergent, but the 92-amino acid C-terminal sequence of FKBP-13 has 46 identical and 20 related residues when compared with FKBP-12. The conserved residues that comprise the drug binding site and rotamase active site of FKBP-12 are completely conserved in FKBP-13. Therefore, the three-dimensional structures of FKBP-12 and the FKBP-12/FK506 complex are likely to be excellent models of the corresponding FKBP-13 structure.

Tb(III) as a fluorescent probe for the structure of bovine serum albumin

Tb(III) was used as a fluorescent probe in the study of the calcium-binding sites on Bovine Serum Albumin (BSA). The fluorescence of Tb(III) is enhanced markedly when bound to BSA and nonradiative energy transfer between two fluorescent tryptophan(Trp) residues and Tb(III) bound to calcium-binding sites on BSA occurred. Experimental results show that the major groups in BSA bound to metal ion are the carboxyl side groups of glutamic acid (Glu) and aspartic acid (Asp). The average distance between the bound Tb(III) and the two tryptophan residues in BSA calculated by a Föster dipole-dipole nonradiative energy transfer mechanism is 1.48 nm.

Characterization of thymus-derived lymphocytes expressing Ti alpha-beta CD3 gamma delta epsilon zeta-zeta, Ti alpha-beta CD3 gamma delta epsilon eta-eta or Ti alpha-beta CD3 gamma delta epsilon zeta-zeta/zeta-eta antigen receptor isoforms: analysis by gene transfection

To characterize the function of the CD3 eta subunit of the T cell receptor (TCR), we have used cDNAs encoding CD3 zeta, CD3 eta, or both to reconstitute a variant of a cytochrome c-specific, I-Ek-restricted murine T cell hybridoma, termed MA5.8, which lacks CD3 zeta and CD3 eta proteins. We provide direct evidence that assembly and surface expression of TCRs can be mediated by either of these subunits separately or together. However, the level of TCR expression on zeta transfectants is up to one order of magnitude greater than that on eta transfectants, implying that CD3 eta is weakly associated with the pentameric Ti alpha-beta CD3 gamma delta epsilon complex and/or inefficient at salvaging the incomplete TCR from lysosomal degradation. As a component of the TCR, the CD3 eta subunit preferentially forms a heterodimer with CD3 zeta, but is also able to form a CD3 eta-eta homodimer. Crosslinking of Ti alpha-beta CD3 gamma delta epsilon zeta-zeta, Ti alpha-beta CD3 gamma delta epsilon eta-eta, or Ti alpha-beta CD3 gamma delta epsilon zeta-zeta/zeta-eta TCR isotypes with anti-CD3 epsilon monoclonal antibody or a cytochrome c peptide epitope on I-Ek antigen-presenting cells mediates signal transduction resulting in reversible cell-cycle arrest of transfected clones. Given the potential for diversity of signals generated by these functional TCR isotypes and the expression of the CD3 eta gene product in the thymus, CD3 eta is likely to play a role in selection and/or activation of thymocytes during development.

A fraction of CD3 epsilon subunits exists as disulfide-linked dimers in both human and murine T lymphocytes

In a T cell antigen receptor complex (TCR), the clonotypic disulfide-linked Ti heterodimer is noncovalently associated with the invariant CD3 polypeptides. The latter are composed of three monomeric subunits (gamma, delta, epsilon) and either a disulfide-linked homodimer (zeta zeta) or a disulfide-linked heterodimer (zeta eta). The exact stoichiometry of the Ti-CD3 subunits in a given complex is still largely unknown. Here, we report the presence of a CD3 epsilon dimer in a fraction of the TCR. When TCRs from both human and murine T lymphocytes were immunoprecipitated with monoclonal antibodies against either CD3 epsilon or Ti, a 40-kDa disulfide-linked dimer was coprecipitated with the other TCR subunits from digitonin lysates. Amino acid sequence analysis of peptides obtained by in situ CNBr cleavage of the 20-kDa product blotted to polyvinyl difluoride membranes from reducing/nonreducing two-dimensional gels identified human CD3 epsilon. Assuming this CD3 epsilon to derive from a homodimer, then either some TCRs contain more than one CD3 epsilon chain or several TCRs are covalently associated with one another via their CD3 epsilon subunits. Although it has been suggested that a putative TCR association with CD2 exists under similar conditions to those utilized to detect CD3 epsilon dimers, the CD2 molecule was not coimmunoprecipitated with the TCR by any of a series of anti-CD3 epsilon monoclonal antibodies. In conjunction with the fact that CD2 and the TCR do not colocalize during conjugate formation between T cells and antigen-presenting cells (Koyasu, S., Lawton, T., Novick, D., Recny, M. A., Siliciano, R. F., Wallner, B. P., and Reinherz, E. L. (1990) Proc. Natl. Acad. Sci. U. S. A. 87, 2603-2607), we conclude that CD2 and the TCR are not physically associated on the T cell surface.

[Effects of harmaline and fluorouracil (5-FU) on human retinoblastoma cell line SO-Rb 50]

Harmaline and 5-FU were incubated with human retinoblastoma (Rb) cell line SO-Rb50 for 72 hours separately before subjected to sampling, viable cell counting and inhibition rate (IR) calculation. With concentration of 12 micrograms/ml, the IR of harmaline to SO-Rb50 cells was 96.6 +/- 1.98%, and that of 5-FU was 93.5 +/- 0.90%; the 50% inhibition concentration (IC50) was 1.437 micrograms/ml for harmaline and 0.321 micrograms/ml for 5-FU. The fact that Rb cells were sensitive to chemical therapy in vitro, but not in vivo, could be due to the blood-retinal barrier. For effective treatment of Rb, besides attempts at early diagnosis and the search for sensitive drugs, studies of the mode of drug delivery are also important.

Characterization of functional GTP binding proteins in Jurkat T cell mutants lacking either CD3-Ti or CD2 surface receptors

G proteins are membrane-bound molecules involved in coupling of surface receptors with signal transduction effector systems in multiple cell types including T lymphocytes. Given that mature T cells which lack antigen receptors (CDl-Ti) are refractory to stimulation through CD2 or other accessory molecules, T cell receptor components likely play a critical role in coupling surface receptors with signal transduction effectors. It has recently been proposed that modulation of T cell receptor components with MAbs results in a physical loss or functional inactivation of G protein(s). In view of the importance of the T cell activation process, we herein examined G proteins in untreated or antibody-modulated Jurkat T cells as well as in genetic variants lacking either CD3-Ti or CD2 surface receptors. 43- and 41-kDa G protein alpha chains are ADP ribosylated with cholera (CTX) and pertussis (PTX) toxins, respectively, in wild type and receptor minus cell populations. In the wild type Jurkat cell line as well as in CD3- and CD2- variants, AlF4- can activate the G protein(s) presumably associated with phospholipase C to generate polyphosphoinositide turnover as well as an increase in cytoplasmic free calcium ions. Furthermore, G protein(s) linked to adenylylcyclase, a pathway which inhibits T lymphocyte activation, can be directly activated with CTX in the absence of CD3-Ti or CD2 on the membrane. Importantly, AlF4- can also induce polyphosphoinositide turnover in Jurkat cells whose T cell receptor proteins have been modulated with anti-CD3 MAb. These data provide functional and biochemical evidence that at least certain G proteins are intact in the absence of surface expression of CD3-Ti or CD2 molecules and imply that CD3-Ti desensitization is not singularly due to G protein loss.

Molecular cloning of the CD3 eta subunit identifies a CD3 zeta-related product in thymus-derived cells

The CD3 eta subunit of the T-cell antigen receptor forms a heterodimeric structure with the CD3 zeta subunit in thymus-derived lymphoid cells and is apparently involved in signal transduction through the receptor. Here we report the primary structure of murine CD3 eta as deduced from protein microsequencing and cDNA cloning. The mature protein is divided into three domains: a 9-amino acid extracellular segment, a 21-amino acid transmembrane segment including a negatively charged residue characteristic of CD3 subunits, and a 155-amino acid cytoplasmic tail. The NH2-terminal sequences of CD3 eta and CD3 zeta are identical through amino acid 122 of each mature protein but then diverge in the remainder of their respective COOH-terminal regions, consistent with alternatively spliced products of a common gene. The cytoplasmic domain of CD3 eta is 42 amino acids larger than that of CD3 zeta but lacks one of six potential tyrosine phosphorylation sites as well as a putative nucleotide binding site previously identified in CD3 zeta. These structural features presumably account for the difference between CD3 eta and CD3 zeta function and are consistent with the notion that CD3 eta may be an important component of a T-cell receptor isoform(s) during thymic development.

Stimulation via CD3-Ti but not CD2 induces rapid tyrosine phosphorylation of a 68-kDa protein in the human Jurkat T cell line

Tyrosine phosphorylation is an early biochemical event associated with surface receptor triggering in many cellular systems. In T lymphocytes, Ag receptor (CD3-Ti) stimulation results in tyrosine phosphorylation of the CD3 zeta subunit. The tyrosine kinase responsible for this modification after CD3-Ti triggering has not been identified. Here we reported that a 68-kDa T cell membrane-associated protein (pp68) in human Jurkat T cells is phosphorylated on tyrosine residues within 1 min after anti-CD3 mAb addition. This induced tyrosine phosphorylation is detected either by in vivo [32P]orthophosphate labeling of the Jurkat T cells or by in vitro [32P]ATP labeling after immunoprecipitation by antiphosphotyrosine antibody. In contrast, mAb stimulation via CD2 and CD4 structures does not induce phosphorylation of pp68. These data are among the first to provide evidence that CD3-Ti and CD2 activation pathways are distinct. Furthermore, they imply that pp68 is itself a tyrosine kinase and/or is a rapidly phosphorylated substrate of a tyrosine kinase.

Stimulation via CD3-Ti but not CD2 induces rapid tyrosine phosphorylation of a 68-kDa protein in the human Jurkat T cell line

Tyrosine phosphorylation is an early biochemical event associated with surface receptor triggering in many cellular systems. In T lymphocytes, Ag receptor (CD3-Ti) stimulation results in tyrosine phosphorylation of the CD3 zeta subunit. The tyrosine kinase responsible for this modification after CD3-Ti triggering has not been identified. Here we reported that a 68-kDa T cell membrane-associated protein (pp68) in human Jurkat T cells is phosphorylated on tyrosine residues within 1 min after anti-CD3 mAb addition. This induced tyrosine phosphorylation is detected either by in vivo [32P]orthophosphate labeling of the Jurkat T cells or by in vitro [32P]ATP labeling after immunoprecipitation by antiphosphotyrosine antibody. In contrast, mAb stimulation via CD2 and CD4 structures does not induce phosphorylation of pp68. These data are among the first to provide evidence that CD3-Ti and CD2 activation pathways are distinct. Furthermore, they imply that pp68 is itself a tyrosine kinase and/or is a rapidly phosphorylated substrate of a tyrosine kinase.

Exchange of H1 histone depends on aggregation of chromatin, not simply on ionic strength

Chromatin solubility was observed at several concentrations of various cations. Spermine and spermidine precipitated (50%) chromatin at about 0.2 mM, Ca2+ and Mg2+ at about 1-2 mM, and Na+ at about 100 mM. Further increases in cation concentration induced more aggregation, but eventually excess cation increased chromatin solubility so that 50% solubility was observed again at 60 mM Mg2+ and 180 mM Na+. H1 histone was 50% released by 80 mM MgCl2 or 425 mM NaCl. Combinations of MgCl2 and NaCl showed that Mg2+ and Na+ are synergistic in the induction of aggregation in lower concentrations (less than 2 mM) of Mg2+ but antagonistic at higher concentrations, and a similar effect of NaCl on spermidine-induced precipitation was shown below and above about 0.2 mM spermidine. At 5 mM, MgCl2 proved capable of precipitating chromatin depleted of H1 histone, but no concentration of NaCl was capable of doing so. These phenomena can be rationalized by supposing that neutralization of chromatin by any cation (including H1 histone) favors aggregation and also that cross-linking of chromatin fibers by multivalent cations (including H1 histone) is also critically important. The exchange of H1 histone between chromatin fragments was tested in various concentrations of different salts. H1 exchange was correlated with chromatin aggregation rather than with ionic strength and thus appears to depend on fiber to fiber contact. Under conditions where H1 exchanges between chromatin fibers that are permitted to make contact with each other, no H1 exchange occurred between chromatin inside the nucleus and chromatin outside, even though H1 histone is capable of passage through the nuclear membrane.

H1 histone exchange is limited to particular regions of chromatin that differ in aggregation properties

Chromatin fragments produced by mild nuclease digestion were chromatographed on Bio-Gel A-50m to give fractions ranging in size from 0.4 to 30 kilobase pair-DNA. The fragments that were larger than about 8-10 nucleosomes accounted for 80% of the chromatin, and the H1/core histone ratio was constant throughout these fractions. When adjusted to 150 mM NaCl, aggregates precipitated in each fraction, the largest fragments yielding 60% and the smallest 25%. In all of these fractions, after aggregation was induced by NaCl, the H1/core histone ratio in the aggregation-resistant chromatin (S) was 0.7 that in the aggregated chromatin (P). To show that the H1 deficiency and aggregation resistance were not produced by transfer of H1 from little fragments to bigger one, big aggregation-resistant fragments were incubated with little aggregation-prone fragments in 75 mM NaCl for 2 h, and readjusted to 150 mM. The little aggregation-prone fragments retained their aggregatibility after exposure to big aggregation-resistant fragments. By mixing [3H]P with [14C]S and vice versa, incubating at 75 mM NaCl for 2 h, and separating P from S with 150 mM NaCl, it was demonstrated that H1 histone did not equilibrate between S and P. Similarly, mixing combinations of radioactive and unlabeled, big and little, S and P fractions, and fractionating by size after 2 h or more incubation at 75 mM NaCl, it was shown that H1 equilibrates between different S fragments, and between different P fragments, but not between S and P. The distribution of H1 variants between S and P fractions was not correlated with the affinity of the variants for DNA. The order of binding affinities was H10 greater than H1ab = H1c, but the deficits of H1's in the aggregation-resistant S fractions were ranked H1ab greater than H1c greater than H10. It is suggested that chromatin is a mosaic of aggregation-resistant and aggregation-prone regions which differ in H1 content quantitatively and qualitatively.