Aristolochic acid I promoted clonal expansion but did not induce hepatocellular carcinoma in adult rats.

Aristolochic acid I (AAI) is a well-known nephrotoxic carcinogen, which is currently reported to be also associated with hepatocellular carcinoma (HCC). Whether AAI is a direct hepatocarcinogen remains controversial. In this study we investigated the association between AAI exposure and HCC in adult rats using a sensitive rat liver bioassay with several cofactors. Formation of glutathione S-transferase placental form-positive (GST-P+) foci was used as the marker for preneoplastic lesions/clonal expansion. We first conducted a medium-term (8 weeks) study to investigate whether AAI had any tumor-initiating or -promoting activity. Then a long-term (52 weeks) study was conducted to determine whether AAI can directly induce HCC. We showed that oral administration of single dose of AAI (20, 50, or 100 mg/kg) in combination with partial hepatectomy (PH) to stimulate liver proliferation did not induce typical GST-P+ foci in liver. In the 8-week study, only high dose of AAI (10 mg · kg-1 · d-1, 5 days a week for 6 weeks) in combination with PH significantly increased the number and area of GST-P+ foci initiated by diethylnitrosamine (DEN) in liver. Similarly, only high dose of AAI (10 mg· kg-1· d-1, 5 days a week for 52 weeks) in combination with PH significantly increased the number and area of hepatic GST-P+ foci in the 52-week study. No any nodules or HCC were observed in liver of any AAI-treated groups. In contrast, long-term administration of AAI (0.1, 1, 10 mg· kg-1· d-1) time- and dose-dependently caused death due to the occurrence of cancers in the forestomach, intestine, and/or kidney. Besides, AAI-DNA adducts accumulated in the forestomach, kidney, and liver in a time- and dose-dependent manner. Taken together, AAI promotes clonal expansion only in the high-dose group but did not induce any nodules or HCC in liver of adult rats till their deaths caused by cancers developed in the forestomach, intestine, and/or kidney. Findings from our animal studies will pave the way for further large-scale epidemiological investigation of the associations between AA and HCC.

[Sporadic cutaneous infections due to nontuberculous mycobacteria: a retrospective study of 37 cases].

OBJECTIVE: To study the clinical and pathological characteristics of sporadic cutaneous infections due to nontuberculous mycobacteria (NTM), and investigate the diagnostic criteria and therapeutic principal. METHODS: Totally 37 cases of sporadic cutaneous infections due to NTM were confirmed in the Department of Dermatology, Peking University People's Hospital from January 2000 to March 2014. The microbiologic and clinical data were reviewed, and their skin biopsy specimens were reassessed. RESULTS: Of all the 37 patients, 30 cases were Mycobacterium marinum infection, 6 were Mycobacterium abscessus infection, and one was Mycobacterium chelonea and Mycobacterium fortuitum infection. Identification of mycobacterial species by analysis of hsp65 gene in tissue DNA was more sensitive than traditional bacterial culture. The most common risk factors were traumatic injuries (21 of 37) and aquarium or fish-related job (21 of 37). One case of Mycobacterium abscessus infection occurred after autologous fat filling. Nodule and plaque were most common lesions in Mycobacterium marinum infection. Twenty-four of the 30 cases of Mycobacterium marinum infection presented with multiple lesions or sporotrichoid spread lesions. Ulceration, papules, abscess, and purulent discharge were observed in cases of Mycobacterium abscessus infection. Infective granuloma was most common histopathological appearance. For the treatment of Mycobacterium marinum infection, rifampin, ethambutol, and clarithromycin were commonly used (combination of two antibiotics, or three antibiotics), with the cure rate 90.00%. Four of the six Mycobacterium abscessus infections cases were cured, and one patient died. CONCLUSION: The most common species of sporadic cutaneous infections due to NTM is Mycobacterium marinum. Traumatic injuries, aquarium or fish-related job, and cosmetic surgeries are common risk factors. Mycobacterium marinum infection often presents with nodules, plaques, and sometimes sporotrichoid spread lesions. Lesions of Mycobacterium abscessus infection may vary. Pathological changes were not species specific, final diagnosis must be made depending on the identification of the microorganism. For the treatment of Mycobacterium marinum infection, excellent outcomes can be achieved by the combination of rifampin and ethambutol, and the combination of clarithromycin and rifampin or ethambutoland. Treatment regimens of Mycobacterium abscessus infection should be decided according to the results of antibiotic susceptibility testing.

Rare earth elements activate endocytosis in plant cells.

It has long been observed that rare earth elements (REEs) regulate multiple facets of plant growth and development. However, the underlying mechanisms remain largely unclear. Here, using electron microscopic autoradiography, we show the life cycle of a light REE (lanthanum) and a heavy REE (terbium) in horseradish leaf cells. Our data indicate that REEs were first anchored on the plasma membrane in the form of nanoscale particles, and then entered the cells by endocytosis. Consistently, REEs activated endocytosis in plant cells, which may be the cellular basis of REE actions in plants. Moreover, we discovered that a portion of REEs was successively released into the cytoplasm, self-assembled to form nanoscale clusters, and finally deposited in horseradish leaf cells. Taken together, our data reveal the life cycle of REEs and their cellular behaviors in plant cells, which shed light on the cellular mechanisms of REE actions in living organisms.

Differential Effects of Naja naja atra Venom on Immune Activity.

Previous studies reported that Naja naja atra venom (NNAV) inhibited inflammation and adjuvant arthritis. Here we investigated the role of NNAV in regulation of immune responses in mice. Oral administration of NNAV to normal mice showed significant increase in natural killer cell activity, B lymphocyte proliferation stimulated by lipopolysaccharides, and antibody production in response to sheep red blood cells. Meanwhile, NNAV markedly decreased T lymphocyte proliferation stimulated by concanavalin A, arrested the cell cycle at G0/G1 phase, and suppressed CD4 and CD8 T cell divisions. Furthermore, NNAV inhibited the dinitrofluorobenzene-induced delayed-type hypersensitivity reaction. This modulation of immune responses may be partly attributed to the selective increase in Th1 and Th2 cytokines (IFN-γ, IL-4) secretion and inhibition of Th17 cytokine (IL-17) production. In dexamethasone-induced immunosuppressed mice, NNAV restored the concentration of serum IgG and IgM, while decreasing the percentage of CD4 and CD8 T-cell subsets. These results indicate that NNAV enhances the innate and humoral immune responses while inhibiting CD4 Th17 and CD8 T cell actions, suggesting that NNAV could be a potential therapeutic agent for autoimmune diseases.

The Protective Effects of Cobra Venom from Naja naja atra on Acute and Chronic Nephropathy.

This study investigated the effects of Naja naja atra venom (NNAV) on acute and chronic nephropathy in rats. Rats received 6 mg/kg adriamycin (ADR) once to evoke the chronic nephropathy or 8 ml/kg 50% v/v glycerol to produce acute renal failure (ARF). The NNAV was given orally once a day starting five days prior to ADR or glycerol injection and continued to the end of experiments. The animals were placed in metabolic cages for 24 h for urine collection for urinary protein determination. The kidney function-related biochemical changes and index of oxidative stress were determined with automatic biochemistry analyzer or colorimetric enzyme assay kits. The pathomorphological changes were observed using light and transmission electron microcopies. The levels of inflammatory cytokines and NF- κ B activation were determined using ELISA kits, Western blot analysis, or immunofluorescence. The results showed that NNAV relieved ADR-induced chronic nephropathy and glycerol-triggered acute renal failure syndromes including proteinuria, hypoalbuminemia, hyperlipidemia, serum electrolyte unbalance, renal oxidative stress, and pathological damages. NNAV reduced kidney levels of TNF- α and IL-1 ß , but it increased the levels of I κ B- α and inhibited NF- κ B p65 nuclear localization. These findings suggest that NNAV may be a valuable therapeutic drug for acute and chronic kidney diseases.

Structural basis for the decrease in the outward potassium channel current induced by lanthanum.

The current of the outward K+ channel in the cell of horseradish treated with La3+ and the direct interaction between La3+ and the K+ channel protein were investigated using the whole-cell patch-clamp technique, molecular dynamics simulation, and quantum chemistry calculation methods. It was found for the first time that La3+ decreases the current of the K+ channel in the horseradish mesophyll cell. The decrease results from the formation of a coordination bond and hydrogen bond between La3+ and the K+ channel protein in the plasma membrane. The direct interaction destroys the native structure of the K+ channel protein, disturbing the function of the K+ channel protein in the cells. The results can provide the theoretical foundation for understanding the interaction between metal ions (especially high-valence metal ions) and the channel protein in organisms, including animal and plant cells.

Mutation of the conserved Asp122 in the linker impedes creatine kinase reactivation and refolding.

Creatine kinase (CK), a key enzyme in maintaining the intracellular energetic homeostasis, contains two domains connected by a long linker. In this research,we found that the mutations of the conserved Asp122 in the linker slightly affected CK activity, structure and stability. The hydrogen bonding and the ion pair contributed 2-5 kJ/mol to the conformational stability of CK. Interestingly, the ability of CK reactivation from the denatured state was completely removed by the mutations. These results suggested that the electrostatic interactions were crucial to the action of the linker in CK reactivation.

[Detection and identification of mycobacterial gene in skin lesions and lymph nodes in patients with sarcoidosis].

OBJECTIVE: To investigate the possible role of mycobacteria in the pathogenesis of sarcoidosis. METHODS: We used nested polymerase chain reaction-restriction fragment length polymorphism (nPCR-RFLP) and gene sequencing method to examine 31 formalin-fixed, paraffin-embedded specimens (including 19 skin lesions and 12 lymph nodes ) obtained from patients with sarcoidosis, 14 normal skin specimens, and 3 cutaneous tuberculosis specimens. RESULTS: The 65kD mycobacterial heat shock protein gene was found in 4 out of 19 (21.1%) skin specimens of sarcoidosis. The mycobacteria included M. tuberculosis (n = 1), M. chelonei (n = 2), and M. gordonae (n = 1). Mycobacterial DNA was negative in 12 lymph node specimens and 14 normal skin specimens. M. tuberculosis gene was detected in all 3 specimens of cutaneous tuberculosis. CONCLUSION: Mycobacteria may play a role in the pathogenesis of cutaneous sarcoidosis.

The conserved Cys254 plays a crucial role in creatine kinase refolding under non-reduced conditions but not in its activity or stability.

Oxidative stress is a common factor that may affect cell survival in extreme or disease-related conditions, and it is important for the cells to develop not only redox homeostatic mechanisms, but also adequate protein-protecting mechanisms to fight against oxidative stress. In this research, we investigated the role of the conserved C254 in the refolding of creatine kinase (CK), a key cytosolic enzyme involved in intracellular energetics. It was found that the conserved C254 did not contribute to the activity, structure, stability and unfolding of CK, but played a crucial role in CK refolding under non-reduced conditions by preventing off-pathway aggregation. This property of C254 might be a result of natural selection of CK to fight against oxidative stresses that are frequently encountered by vertebrate cells. The results herein not only confirmed that the reduced condition is important to the activity, structural stability and folding of cytosolic proteins, but also highlighted that it is also crucial for cytosolic proteins to maintain the ability to fold correctly under non-reduced conditions.