[Research progress of optical coherence tomography in the airway]

Optical coherence tomography (OCT) is a specialized optical imaging technique with a history of more than 30 years, known as'optical biopsy' because of its high resolution and high sensitivity. OCT has been used in the airway for more than 20 years, and researchers have explored and improved the imaging methods of OCT in the airway, focusing mainly on expanding the imaging site and enriching the imaging content. In terms of broadening the imaging site, it covers the airway from generation 0 to 9. In terms of enriching imaging content, additional assessment of airway wall blood vessels, airway smooth muscle, fibrous tissue, and airway compliance can be performed. It plays an important role in the study of various respiratory diseases. Therefore, this paper mainly summarized the exploration of the imaging site and content of airway OCT as follows.

Dietary pattern interfered with the impacts of pesticide exposure by regulating the bioavailability and gut microbiota

Dietary intake is an essential way for pesticides to enter the human body. The effects of dietary pattern on the risks of pesticides and what diet can reduce the damage are largely unknown. Here, it is found that Mediterranean diet and Vegetarian diet could alleviate insulin resistance and obesity induced by chlorpyrifos, while Western diet could aggravate that. Gut microbiota and chlorpyrifos bioavailability mediated by the diets were involved in these effects. Both the dietary pattern and chlorpyrifos could change the composition of gut microbiota. Chlorpyrifos caused gut dysbacteriosis which was an important reason for the induced metabolic syndrome. Mediterranean diet and Vegetarian diet could maintain gut microbiota homeostasis and increase intestinal bacteria producing short-chain fatty acids, repair the gut microbiota and intestinal barrier damaged by chlorpyrifos. High dietary fat intake increased the bioavailability of chlorpyrifos, which aggravated the gut dysbacteriosis and destruction of intestinal integrity. Thus, the amount of endotoxin entering the blood increased and caused low-grade inflammation, which was also an important pathway of metabolic syndrome. The results suggested that although it was almost impossible to avoid the exposure to pesticides in modern life, healthy diets could regulate beneficial gut microbiota and alleviate the risk of pesticide exposure.

[Effectiveness and safety of robotic assisted-bronchoscopy system in locating and removing spring coils placed in the peripheral lung of beagle dogs: a pilot study]

Objective: To evaluate the effectiveness and safety of the robotic assisted bronchoscope system for localizing and removing the spring coils that placed in the peripheral lung of beagle dogs. Methods: The study was conducted from June 18th to June 20th, 2021. Metallic lung coils were placed as the simulated lesions to the periphery of the lungs of two adult male beagle dogs using a bronchoscope under general anesthesia. The navigation path was planned by the navigation function that built in the robotic bronchoscope system. After training, the doctors operated the robotic bronchoscope system to locate and remove the coils from the lung. The navigation success rate, sampling success rate, position of the coil, navigation time, sampling time, and operation time were evaluated. The damage to the airway mucosa during the operation and the vital signs of the beagles during and post-operation were accessed. Chest computerized tomography (CT) was performed post-operation to detect if there were complications such as pneumothorax and bleeding. Results: A total of 12 spring coils were successfully inserted into the two beagles. All the navigation paths of the simulated lesions were successfully planned. The navigation success rate was 12/12. The navigation time was (43.9±19.8) seconds. The distance between the tip of the flexible endoscope arm and the target point measured by the navigation system was (6.93±2.15) mm. The locations of the simulated lesions were distributed in the 6th-8th generation of bronchi. The sampling success rate was 12/12. The sampling time was (42.4±11.3) seconds. There was no pneumothorax or mediastinal emphysema after the placement of the coil. The vital signs of the beagle dogs were stable throughout the operation, and no operation-related or postoperative complications occurred. Conclusions: The robotic bronchoscope system can be used to locate and remove the spring coils from the peripheral lung of beagle dogs, and the procedure is simple and safe. It suggests that the robotic bronchoscopy system has great clinical significance in the sampling and diagnosis of peripheral lung lesions.

Malnutrition affects cholesterol paradox in coronary artery disease: a 41,229 Chinese cohort study

Background

Several studies found that baseline low LDL-C concentration was associated with poor prognosis in patients with acute coronary syndrome (ACS), which was called “cholesterol paradox”. Low LDL-C concentration may reflect underlying malnutrition, which was strongly associated with increased mortality. We objected to investigate the cholesterol paradox in patients with CAD and the effects of malnutrition.

Method

A total of 41,229 CAD patients admitted to Guangdong Provincial People's Hospital in China were included in this study from January 2007 to December 2018, and divided into two groups (LDL-C <1.8 mmol/L, n=4,863; LDL-C ≥1.8 mmol/L, n=36,366). We used Kaplan-Meier method and Cox regression analyses to assess the association between LDL-C levels and long-term all-cause mortality and the effect of malnutrition.

Result

In this real-world cohort (mean age 62.94 years; 74.94% male), there were 5257 incidents of all-cause death during a median follow-up of 5.20 years [Inter-quartile range (IQR): 3.05–7.78 years]. Kaplan–Meier analysis showed that low LDL-C levels were associated with worse prognosis. After adjusting for baseline confounders (e.g., age, sex and comorbidities, etc.), multivariate Cox regression analysis revealed that low LDL-C level (<1.8mmol/L) was not significantly associated with all-cause mortality (adjusted HR, 1.04; 95% CI, 0.96–1.24). After adjustment of nutritional status, risk of all-cause mortality of patients with low LDL-C level decreased (adjusted HR, 0.90; 95% CI, 0.83–0.98). In the final multivariate Cox model, low LDL-C level was related to better prognosis (adjusted HR, 0.91; 95% CI, 0.84–0.99).

Conclusion

Our results demonstrate that the cholesterol paradox persisted in CAD patients, but disappeared after accounting for the effects of malnutrition.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): the National Natural Science Foundation of China (Grant No. 81670339 and Grant No. 81970311), Cardiovascular Research Foundation Project of the Chinese Medical Doctor Association (SCRFCMDA201216)

Primary vs myocutaneous flap closure of perineal defects following abdominoperineal resection for colorectal disease: a systematic review and meta-analysis

AIM

Perineal wound complications after abdominoperineal resection (APR) have become a major clinical challenge. Myocutaneous flap closure has been proposed in place of primary closure to improve wound healing. We conducted this comprehensive meta-analysis to evaluate the current scientific evidence of primary closure vs myocutaneous flap closure of perineal defects following APR for colorectal disease.

METHODS

We systematically searched the MEDLINE, Embase, PubMed, Web of Science and Cochrane Library databases to identify all relevant studies. After data extraction from the included studies, meta-analysis was performed to compare perioperative outcomes of primary closure and myocutaneous flap closure.

RESULTS

Eighteen studies with a total of 17 913 patients (16 346 primary closure vs 1567 myocutaneous flap closure) were included. We found that primary closure was significantly associated with higher total perineal wound complications (P = 0.007), major perineal wound complications (P < 0.001) and perineal wound infection (P = 0.001). On the other hand, myocutaneous flap closure takes more operation time (P < 0.001) and increases the risk of perineal wound dehiscence (P = 0.01), deep surgical site infection (P < 0.001), enterocutaneous fistulas (P = 0.03) and return to the operating room (P = 0.0005). There were no significant differences between the two groups for other outcomes.

CONCLUSIONS

This is the first systematic review with meta-analysis comparing primary closure with myocutaneous flap closure of perineal defects after APR for colorectal disease. Although taking more operation time and an increased risk of specific complications, the pooled results have validated the use of myocutaneous flaps for reducing total/major perineal wound complications. More investigations are needed to draw definitive conclusions on this dilemma.

Supplemented Organic and Inorganic Selenium Affects Milk Performance and Selenium Concentration in Milk and Tissues in the Guanzhong Dairy Goat

Trace amounts of selenium (Se) are essential for several organisms, and deficiencies therein have adverse effects on growth, development, and reproduction; this is particularly significant in animals raised for milk and livestock production. To study the effect of Se on Guanzhong dairy goats, their diets were supplemented with different sources (inorganic or organic) and Se concentrations (0.2 or 0.4 mg Se/kg). A non-Se-fortified basal diet served as a negative control, and a sixth treatment group received both inorganic and organic Se sources (0.2 mg Se/kg diet each). Dietary Se supplementation increased milk production, with organic Se being more effective than inorganic Se. Selenium supplementation also increased Se concentration and glutathione peroxidase activity in whole blood, with organic Se more effective than inorganic Se at the same Se concentration. With increasing Se in diets, the Se content in milk increased markedly, reaching a plateau value at day 30 in all groups, and organic Se (0.4 mg/kg diet) had the best effect. In addition, dietary Se sources and concentrations markedly affected Se concentrations in different tissues and organs. Thus, organic Se supplementation of a basal diet at 0.4 mg/kg is practically applicable for Se-enriched milk and meat production in Guanzhong dairy goats.

Hepcidin is an endogenous protective factor for osteoporosis by reducing iron levels

Postmenopausal osteoporosis is a global health issue. Although a lack of estrogen is considered the major reason for postmenopausal osteoporosis, other factors might also contribute the etiology of the disease. In previous reports, we and others proposed that iron accumulation after menopause accelerates osteoporosis, and here, we genetically modified the expression of an endogenous hormone, hepcidin, to modulate iron status in a mouse model. Our results show that hepcidin levels negatively correlate with bone loss in both knockout and overexpression (with ovariectomy) murine models. In addition, iron overload enhances reactive oxygen species (ROS) activity and attenuates the functions of primary osteoblasts, while iron depletion could reverse this phenomenon through inhibiting the functions of primary osteoclasts. Therefore, our results provide more evidence of the 'iron accumulation' hypothesis, which suggests that high iron levels are risk factors for osteoporosis, and the 'Huang's hypothesis' that hepcidin is a potential drug target for the prevention of postmenopausal osteoporosis.

Mechanisms of vasorelaxation induced by total flavonoids of Euphorbia humifusa in rat aorta

Euphorbia humifusa Willd. (EH), rich in flavonoids, has long been used for the treatment of bacillary dysentery and enteritis in China, and is known to have antioxidant, hypotensive and hypolipidemic properties. However, the vasorelaxant effect of total flavonoids of EH (TFEH) and action mechanisms are not clearly defined yet. The aim of the present study was to investigate the effects of TFEH on the vascular tension and its underlying mechanisms. Experiments were performed in rat thoracic aorta using the organ bath system. TFEH (0.01 - 100 μg/ml) caused a concentration-dependent vasorelaxation, which was dependent on a functional endothelium, and were significantly attenuated by inhibitors of endothelial NO synthase, its upstream signaling pathway, PI3K/Akt, and soluble guanylate cyclase, but not by blockade of K_Ca channel, K_ATP channel, cyclooxygenase, muscarinic and β-adrenergic receptors. Extracellular Ca²⁺ depletion, and pre-treatment with modulators of the store-operated Ca²⁺ entry channels, Gd³⁺ and 2-aminoethyl diphenylborinate, significantly attenuated the TFEH-induced vasorelaxation. Our findings suggest that TFEH elicit vasorelaxation via endothelium-dependent NO-cGMP pathway through activation of PI3K/Akt- and Ca²⁺-eNOS-NO signaling. Further, it is suggested that TFEH-induced activation of the NO-soluble guanylate cyclase-cGMP-protein kinase G signaling relaxes vascular smooth muscle cells through an inhibition of the L-type Ca²⁺ channel activity.

Mesenchymal Stem Cell Modulates T Follicular Helper Cell to Induce Immunotolerance of Islet Allograft

OBJECTIVE

To verify whether mesenchymal stem cells protected the islet allograft via modulating follicular B helper T cells (Tfh) cells.

METHODS

The recipient mice were divided into 5 groups. Group A: the diabetic group (n = 12); Group B: islets alone group (n = 12); Group C: MSCs and islets co-transplanted group (n = 12, MSCs = 0.5 × 10(6)); Group D: MSCs and islets co-transplanted group (n = 12, MSCs = 1 × 10(6)); Group E: MSCs and islets co-transplanted group (n = 12, MSCs = 2 × 10(6)); One control group of normal NOD mice was set as well. ELISA was used to examine the autoantibody level of GAD65 Ab, insulin autoantibodies, and insulin. The Tfh count was determined by fluorescence-activated cell sorting. The insulin expression of islet grafts, the infiltration of lymphocytes, and the Tfh cells were observed via hematoxylin and eosin staining and immunohistochemical staining.

RESULTS

There was significant prolonged graft survival and more insulin expression of islet grafts observed in the co-transplant group. A lower level of the Tfh cells and autoantibody GAD65 Ab, insulin autoantibodies were also presented in the co-transplant group (P < .01). The infiltration of lymphocytes in the co-transplant group was notably less than in the islet-alone group (P < .01).

CONCLUSIONS

Mesenchymal stem cells were able to protect the islet allograft by regulating the follicular helper T cells.

Rumex acetosa L. induces vasorelaxation in rat aorta via activation of PI3-kinase/Akt- AND Ca(2+)-eNOS-NO signaling in endothelial cells

Rumex acetosa L. (RA) (Polygonaceae) is an important traditional Chinese medicine (TCM) commonly used in clinic for a long history in China and the aerial parts of RA has a wide variety of pharmacological actions such as diuretic, anti-hypertensive, anti-oxidative, and anti-cancer effects. However, the mechanisms involved are to be defined. The purpose of the present study was to evaluate the vasorelaxant effect and define the mechanism of action of the ethanol extract of Rumex acetosa L. (ERA) in rat aorta. ERA was examined for its vascular relaxant effect in isolated phenylephrine-precontracted rat thoracic aorta and its acute effects on arterial blood pressure. In addition, the roles of the nitric oxide synthase (NOS)-nitric oxide (NO) signaling in the ERA-induced effects were tested in human umbilical vein endothelial cells (HUVECs). The phosphorylation levels of Akt and eNOS were assessed by Western blot analysis in the cultured HUVECs. ERA induced endothelium-dependent vasorelaxation. The ERA-induced vasorelaxation was abolished by L-NAME (an NOS inhibitor) or ODQ (a sGC inhibitor), but not by indomethacin. Inhibition of PI3-kinase/Akt signaling pathway markedly reduced the ERA-induced vasorelaxation. In HUVECs, ERA increased NO formation in a dose-dependent manner, which was inhibited by L-NAME and by removing extracellular Ca(2+). In addition, ERA promoted phosphorylation of Akt and eNOS, which was prevented by wortmannin and LY294002, indicating that ERA induces eNOS phosphorylation through the PI3-kinase/Akt pathway. Further, in anesthetized rats, intravenously administered ERA decreased arterial blood pressure in a dose-dependent manner through an activation of the NOS-NO system. In summary, the ERA- induced vasorelaxation was dependent on endothelial integrity and NO production, and was mediated by activation of both the endothelial PI3-kinase/Akt- and Ca(2+)-eNOS-NO signaling and muscular NO-sGC-cGMP signaling.

Process of aerenchyma formation and reactive oxygen species induced by waterlogging in wheat seminal roots

The development and regulation of aerenchyma in waterlogged conditions were studied in the seminal roots of wheat. Evans blue staining and the first cell death position indicated that the cortical cell death began at the root mid-cortex cells in flooding conditions. Continuous waterlogging treatment caused the spread of cell death from the mid-cortex to the neighboring cells and well-developed aerenchyma was formed after 72 h. Meanwhile, the formation of radial oxygen loss barrier was observed in the exodermis owing to the induction of Casparian bands and lignin deposition. Analysis of aerenchyma along the wheat root revealed that aerenchyma formed at 10 mm from the root tip, significantly increased toward the center of the roots, and decreased toward the basal region of the root. In situ detection of radial oxygen species (ROS) showed that ROS accumulation started in the mid-cortex cells, where cell death began indicating that cell death was probably accompanied by ROS production. Further waterlogging treatments resulted in the accumulation of ROS in the cortical cells, which were the zone for aerenchyma development. Accumulation and distribution of H₂O₂ at the subcellular level were revealed by ultracytochemical localization, which further verified the involvement of ROS in the cortical cell death process (i.e., aerenchyma formation). Furthermore, gene expression analysis indicated that ROS production might be the result of up-regulation of genes encoding for ROS-producing enzymes and the down-regulation of genes encoding for ROS-detoxifying enzymes. These results suggest that aerenchyma development in wheat roots starts in the mid-cortex cells and its formation is regulated by ROS.

Cell wall degradation and the dynamic changes of Ca2+ and related enzymes in the developing aerenchyma of wheat (Triticum aestivum L.) under waterlogging

This research was aimed to study the cell wall degradation and the dynamic changes of Ca2+ and related enzymes in developing aerenchyma of wheat root under waterlogging. An examination of morphological development by light and electron microscope revealed that the structure of cell wall in middle cortical cells remained intact after 12 h of waterlogging and turned thinner after waterlogging for 24 h. At 48 h, the aerenchyma has been formed. The cellulase activity gradually increased in middle cortical cells within 24 h of waterlogging, and decreased with the formation of aerenchyma. Fluorescence detection and subcellular localization of Ca2+ showed the dynamic changing of Ca2+ at the cellular and subcellular levels during the development of aerenchyma. The activity of Ca2+-ATPase enhanced markedly in intercellular space, plasma membrane and tonoplast of some middle cortical cells after 8 h of waterlogging and remained high after 24 h, but it decreased after 48 h of waterlogging. All these suggests that cellulase, Ca2+ and Ca2+-ATPase show a dynamic distribution during the aerenchyma development which associated with the cell wall degradation of middle cortical cells. Moreover, there is a feedback regulation between Ca2+ and Ca2+-ATPase.

Phylogenetic and Pathogenic Analyses Show That the Causal Agent of Apple Ring Rot in China Is Botryosphaeria dothidea

Apple ring rot and Botryosphaeria canker are severe diseases affecting apple production in China, but there is confusion regarding which pathogens cause these diseases and their similarity to other diseases, such as white rot of apple, and ring rot and Botryosphaeria canker of pear. In this study, the pathogen of apple ring rot in China was compared with the pathogen of apple ring rot in Japan and Korea, the pathogen of Botryosphaeria canker of apple and pear in China, the pathogen of pear ring rot in China, and the pathogen of white rot of apple in the United States. Comparisons were based on morphology, pathogenicity on branches and fruit, and sequences of rDNA in the internal transcribed spacer region and of the β-tubulin and actin genes. Results showed that the causal agent of apple ring rot and Botryosphaeria canker of apple in China was Botryosphaeria dothidea, which has also been reported to be the pathogen of apple ring rot in Korea and Japan. Pathogenicity tests showed that B. dothidea infection on apple and pear branches may induce wart or canker symptoms depending on the conditions. These results are consistent with the hypothesis that the same pathogen causes the wart symptom of apple ring rot and the Botryosphaeria canker symptom on apple branches in China. The results also suggest that apple ring rot and white rot are the same disease and are caused by B. dothidea. Finally, B. dothidea isolates from pear and other fruit or forest trees may serve as inoculum for apple ring rot.

Ketamine inhibits polymorphonuclear leucocyte CD11b expression and respiratory burst activity in endotoxemic rats

OBJECTIVE AND DESIGN

To observe the effect of ketamine on polymorphonuclear leucocytes (PMN) adhesion and respiratory burst activity in endotoxemia rats.

MATERIALS

30 rats were randomly allocated to five groups: rats challenged with intraperitoneal injection of saline (saline group); challenged with intraperitoneal injection of LPS 10 mg/kg (LPS group); challenged with intraperitoneal injection of LPS 10 mg/kg and treated by intraperitoneal injection of ketamine 5, 25, 50 mg/kg at 0, 1, 2, 3, 4, 5 h after the injection of LPS, respectively (three ketamine treatment groups).

METHODS

PMN respiratory burst and CD11b expression were measured with flow cytometry at the end of 1 h, 4 h, and 6 h.

RESULTS

LPS challenge significantly increased PMN respiratory burst activity and CD11b expression when compared with the saline group (p < 0.01). There was a significant decrease in LPS-induced PMN respiratory burst activity and CD11b expression in three ketamine treatment groups when compared with LPS group (p < 0.01).

CONCLUSIONS

Ketamine significantly inhibits PMN CD11b expression and respiratory burst activity in endotoxemic rats.

Stereoselective kinetic study of hexaconazole enantiomers in the rabbit

Hexaconazole [(RS)-2-(2,4-dichlorophenyl)-1-(1H-1,2,4-triazol-1-yl)hexan-2-ol] is a potent triazole fungicide. The (-) isomer accounts for most of the fungicidal activity. The stereo- and/or enantioselective kinetics of hexaconazole were investigated in rabbits by intravenous injection. The concentrations of (-)- and (+)-hexaconazole in plasma, liver, and kidney tissue were determined by HPLC with a cellulose tris(3,5-dimethylphenylcarbamate)-based chiral stationary phase and by gas chromatography-mass spectrometry. After intravenous administration of racemic hexaconazole (rac-hexaconazole) at 30 mg/kg, plasma, liver, and kidney levels of the (+)-enantiomer decreased more rapidly than those of the (-)-enantiomer. The (-)-/(+)-enantiomer ratio of the area under the concentration-time curve (AUC(0-infinity)) was 1.35. The total plasma clearance value (CL) of (+)-enantiomer was more than 1.3-fold higher than that of the (-)-hexaconazole. The enantiomeric ratio (ER) increased with time in plasma, liver, and kidney. Other pharmacokinetic parameters of the enantiomers were also different. These results indicate substantial stereoselectivity in the kinetics of hexaconazole enantiomers in rabbits.

Ketamine inhibits LPS-induced calcium elevation and NF-kappa B activation in monocytes

OBJECTIVE

To investigate whether ketamine could inhibit lipopolysaccharide (LPS)-induced intracellular calcium elevation and NF-kappa B activation in monocytes.

MATERIALS AND METHODS

Isolated rat monocytes were challenged with 10 microg/ml LPS with or without the presence of various concentrations of ketamine (10, 100, 1000 microM). Intracellular calcium was monitored by laser confocal microscopy. NF-kappa B activity of the nuclear extracts of monocytes was analyzed by electrophoretic mobility shift assay (EMSA).

RESULTS

LPS provoked a significant calcium elevation and enhanced NF-kappa B activity in monocytes. Ketamine above concentration of 100 microM inhibited endotoxin-induced intracellular calcium elevation and NF-kappa B activity. Ketamine itself had no effect on either of them.

CONCLUSIONS

These findings suggest that ketamine could suppress NF-kappa B in monocytes exposed to endotoxin, and this anti-inflammatory effect might act through attenuating intracellular calcium elevation.

The interplay between Mad and Myc in proliferation and differentiation

Members of the Myc family of transcription factors are key regulators of cell proliferation, and excessive levels of Myc lead to tumor formation. Mad family proteins are related to Myc, but they antagonize the oncogenic activity of Myc in cell-culture assays. Here, we examine current models of Mad function and the relationship between Mad and Myc in cell proliferation, differentiation and tumorigenesis.

[Determination of optical purity of SR-bioallethrin enantiomers by chiral high performance liquid chromatography]

A chiral stationary phase(CSP) was prepared by coating cellulose-tris (3,5-dimethylphenylcarbamate) onto aminopropylated spherical silica gel. On the CSP, the chiral separation of the bioallethrin enantiomers has been investigated and under the optimum conditions the optical purity of three samples of SR-bioallethrin enantiomers was determined by peak area. The results show that the method established is very ideal for determining the optical purity and evaluating the quality of the samples.

Spontaneous hepatocellular carcinoma is reduced in transgenic mice overexpressing human O6- methylguanine-DNA methyltransferase

O(6)-methylguanine (O(6)mG) is a potent mutagenic and procarcinogenic DNA lesion. Organisms have evolved with a DNA repair mechanism that largely ameliorates the deleterious effects of O(6)mG through a direct reversal mechanism by a protein termed O(6)-methylguanine-DNA methyltransferase (MGMT). However, the contribution of O(6)mG to carcinogenesis, in the absence of known exposure to agents that produce it, has not been defined. Nontransgenic C3HeB male mice have a high frequency of spontaneous liver tumors. Transgenic CeHeB/FeJ mice expressing human MGMT (hMGMT) were generated that had elevated hepatic MGMT activity. The spontaneous development of hepatocellular carcinoma was significantly reduced in those mice expressing hMGMT compared with nontransgenic C3HeB/FeJ male mice. No differences were detected in spontaneous mutant frequencies in lacI transgenes in mice carrying hMGMT compared with that without hMGMT but the proportion of GC to AT transition mutations was lower in the transgenic mice carrying hMGMT as well as lacI. Tumors that arose in C3HeB/FeJ transgenic mice were largely deficient in hMGMT protein as determined by immunohistochemistry with a monoclonal antibody directed against hMGMT. Together these data indicate that spontaneous O(6)mG lesions induced hepatocellular carcinogenesis in C3HeB/FeJ male mice. These transgenic mice represent a rare example of reduced spontaneous carcinogenesis.

[The cloning of apple ferritin gene (Apfl) from Malus xiaojinensis Cheng et Jiang and its structure analysis]

The special primers were designed based on the sequence information of plant ferritin genes reported in the literature and used for polymerase chain reaction (PCR) with the genomic DNA of Malus xiaojinensis Cheng et Jiang in an attempt to clone apple ferritin gene. A single fragment of 771 bp was successfully obtained from the PCRs and cloned in this study. The sequence and homology analysis results of the fragment showed that the deduced amino acids of the fragment had a ninety-nine percent homology to that of the soybean ferritin gene reported by Lescure et al. (1991). A comparison in details of the nucleotide sequence of the clone and that of the soybean ferritin gene showed that they consisted of the same open reading frame (ORF, 753 bp) and that the cloned fragment had complete initial and stop codes. Within the ORF no introns were found and there were no nucleotide difference in the transit peptide region (TP) of the gene, but five nucleotide mutations were found in the mature peptide region (MP), among which four were synonymous mutations.

Health span and life span in transgenic mice with modulated DNA repair

One way to better understand the contribution of DNA repair, DNA damage, and mutagenesis in aging would be to enhance DNA repair activity, lower DNA damage, and lower mutagenesis. Because the repair protein O6-methylguanine-DNA methyltransferase (MGMT) acts alone and stoichiometrically, the human MGMT (hMGMT) cDNA was selected to test the feasibility of enhancing DNA repair activity in transgenic mice. MGMT activity is largely responsible for ameliorating the deleterious effects of O6-methylguanine (O6mG) lesions in DNA in a direct reversal mechanism. A transgene was constructed consisting of a portion of the human transferrin (TF) promoter and hMGMT cDNA such that hMGMT is expressed in transgenic mouse brain and liver. Expression of hMGMT was associated with a significant reduction in the occurrence of an age-related hepatocellular carcinoma in male mice at 15 months of age. Longitudinal and cross-sectional studies were initiated to determine whether the reduced incidence of hepatocellular carcinoma would impact median or maximum life span. The cross-sectional study performed on 15-month-old male animals confirmed the reduced occurrence of spontaneous hepatocellular carcinoma. At 30 months of age, however, the occurrence of hepatocellular carcinoma in at least one transgenic line was similar to that for nontransgenic animals. The longitudinal study is ongoing; however, at present no significant differences in life span have been detected. Tissues expressing the MGMT transgene also displayed greater resistance to alkylation-induced tumor formation. These results suggest that transgenes can be used to direct enhanced DNA repair gene expression and that enhanced expression can protect animals from certain spontaneous and induced tumors.

Medical significance of cardiovascular function in hibernating mammals

1. The hibernating mammals inherited a stable cardiovascular function as a result of adaptation to extreme external and internal environments during hibernation. 2. The cardiovascular function of a hibernator is characterized by three distinct features: (i) tolerance of hypothermia; (ii) resistance to dysrhythmia; and (iii) endurance of hypoxia. All these have clinical relevance in cardiovascular disorders in humans. 3. We suggest that the hibernating mammal can serve as a useful animal model for research into the cardiovascular system.

Alpha-stat calibration of indo-1 fluorescence and measurement of intracellular free calcium in rat ventricular cells at different temperatures

To explore how to manage pH when calibrating Ca2+ probes at different temperatures, the dissociation constant (Kd) of indo-1 was determined both in pH-stat (pH is fixed despite the temperature) and in alpha-stat (pH changes with temperature as in cells). The results showed that the Kd was much more sensitive to temperature in pH-stat than in alpha-stat, demonstrating that alpha-stat calibration should be preferred when using a Ca2+ probe to measure intracellular free calcium ([Ca2+]i) at different temperatures. Based on the calibration in situ and in alpha-stat, we showed a striking increase of [Ca2+]i from 141+/-8 nM at 30 degrees C to 218+/-22 nM at 10 degrees C in indo-1 loaded rat ventricular cells, which supports that intracellular calcium overload takes place in cardiac myocytes of non-hibernating mammals during hypothermia.

XRCC2 and XRCC3, new human Rad51-family members, promote chromosome stability and protect against DNA cross-links and other damages

The phenotypically similar hamster mutants irs1 and irs1SF exhibit high spontaneous chromosome instability and broad-spectrum mutagen sensitivity, including extreme sensitivity to DNA cross-linking agents. The human XRCC2 and XRCC3 genes, which functionally complement irs1 and irs1SF, respectively, were previously mapped in somatic cell hybrids. Characterization of these genes and sequence alignments reveal that XRCC2 and XRCC3 are members of an emerging family of Rad51-related proteins that likely participate in homologous recombination to maintain chromosome stability and repair DNA damage. XRCC3 is shown to interact directly with HsRad51, and like Rad55 and Rad57 in yeast, may cooperate with HsRad51 during recombinational repair. Analysis of the XRCC2 mutation in irs1 implies that XRCC2's function is not essential for viability in cultured hamster cells.

[Extracellular ATP: effects, sources and fate]

The change of extracellular adenosine triphosphate (ATP) concentration affects many important physiological functions significantly. As a transmitter, ATP acts on neuro-effector junction directly and/or modulates the release of other neurotransmitters. By acting on the various P2-purinoceptors or ionic channels on the membrane, ATP also has some striking effects on cell activities. This review focused on the latest advances on the research of extracellular ATP in the respects of discovering and confirming ATP as a transmitter, the source, subtypes of P2-purinoceptors, the receptor-mediated reactions, and the degradation of extracellular ATP.

Cloning and characterization of the promoter of baboon XRCC1, a gene involved in DNA strand-break repair

The DNA repair gene XRCC1 was the first cloned human DNA repair gene involved in resistance to ionizing radiation. Previous studies have shown that rodent and baboon homologs of XRCC1 are expressed in all tested tissues with significantly higher levels in testis. Furthermore, expression of murine XRCC1 is most abundant in pachytene spermatocytes and round spermatids. To begin to study regulation of XRCC1 expression, the 5' region of baboon XRCC1 was cloned and characterized. 400 bp of 5'-flanking region showed the greatest promoter activity, while -194 to -8 bp of the 5'-flanking region displayed core promoter activity in transient transfection assays. A comparison between baboon and human 5'-flanking sequences in the core promoter region revealed a potential CAAT-box, an imperfect CREB-binding site and two putative Sp1-binding sites. Results from transient transfection assays in which each putative binding site was individually mutated, indicated that the distal Sp1-binding site has a functional role in transcription. In comparison, both putative Sp1-binding sites bound protein(s) from HeLa cell nuclear extracts in vitro. In vitro binding was lost when mutated Sp1 sites were used in gel mobility shift assays. Finally, anti-Sp1 antibodies produced mobility supershifts, thereby indicating Sp1 or an Sp1-like protein bound to the DNA fragment in vitro.

Dependence of myocardial hypothermia tolerance on sources of activator calcium

To determine the relationship between cardiac hypothermia tolerance and the sources of activator calcium, we selectively modified either the sarcolemmal calcium permeability by nifedipine or the sarcoplasmic reticulum function by caffeine in papillary muscles from both the rat, as a cold sensitive model, and the ground squirrel, Citellus dauricus, a deep hibernator. Both force-interval relationship and cooling performance were investigated. At 25 degrees C, the slope of the force-interval curve of the ground squirrel was nearly double that of the rat. At shorter test intervals 0.5 muM nifedipine moved the curve down with little effect at longer intervals, and the curve slope increased. Caffeine (1 mM) decreased the peak force and eliminated its dependence upon test interval. When the temperature was lowered, rat preparations showed a marked increase of resting tension and aftercontraction between 7 and 12 degrees C and became inexcitable. In contrast, they maintained contractility down to a few degrees above 0 degrees C without aftercontraction and increased resting tension in the ground squirrel. In the rat nifedipine shortened the contractions, prevented the increase of resting tension, and minimized aftercontractions, with little improvement of contractility. Caffeine prolonged the contractions, caused a striking increase of resting tension and aftercontractions, and finally disabled the contractility at about 5-10 degrees C, even in the ground squirrel. We conclude that depressed calcium influx helps to prevent hypothermic calcium overload of the cardiac cells. Good function of the sarcoplasmic reticulum is essential for tolerance of hypothermia by cardiac cells. A suggestion that may improve the hypothermic tolerance of the myocardium from nonhibernators is postulated.

The human XRCC9 gene corrects chromosomal instability and mutagen sensitivities in CHO UV40 cells

The Chinese hamster ovary (CHO) mutant UV40 cell line is hypersensitive to UV and ionizing radiation, simple alkylating agents, and DNA cross-linking agents. The mutant cells also have a high level of spontaneous chromosomal aberrations and 3-fold elevated sister chromatid exchange. We cloned and sequenced a human cDNA, designated XRCC9, that partially corrected the hypersensitivity of UV40 to mitomycin C, cisplatin, ethyl methanesulfonate, UV, and gamma-radiation. The spontaneous chromosomal aberrations in XRCC9 cDNA transformants were almost fully corrected whereas sister chromatid exchanges were unchanged. The XRCC9 genomic sequence was cloned and mapped to chromosome 9p13. The translated XRCC9 sequence of 622 amino acids has no similarity with known proteins. The 2.5-kb XRCC9 mRNA seen in the parental cells was undetectable in UV40 cells. The mRNA levels in testis were up to 10-fold higher compared with other human tissues and up to 100-fold higher compared with other baboon tissues. XRCC9 is a candidate tumor suppressor gene that might operate in a postreplication repair or a cell cycle checkpoint function.

Molecular marker heterozygosity and hybrid performance in indica and japonica rice

An essential assumption underlying markerbased prediction of hybrid performance is a strong linear correlation between molecular marker heterozygosity and hybrid performance or heterosis. This study was intended to investigate the extent of the correlations between molecular marker heterozygosity and hybrid performance in crosses involving two sets of rice materials, 9 indica and 11 japonica varieties. These materials represent a broad spectrum of the cultivated rice gene pool including landraces, primitive cultivars, historically important cultivars, modern elite cultivars and parents of superior hybrids. Varieties within each set were intermated in all possible nonreciprocal pairs resulting in 36 crosses in the indica set and 55 in the japonica set. The F1s and their parents, 111 entries in total, were examined for performance of seven traits in a replicated field trial. The parents were surveyed for polymorphisms using 96 RFLP and ten SSR markers selected at regular intervals from a published molecular marker linkage map. Molecular marker genotypes of the F1 hybrids were deduced from the parental genotypes. The analysis showed that, with very few exceptions, correlations in the indica dataset were higher than in that of their japonica counterparts. Among the seven traits analyzed, plant height showed the highest correlation between heterozygosity and hybrid performance and heteorsis in both indica and japonica datasets. Correlations were low to intermediate between hybrid performance and heterozygosity (both general and specific) in yield and yield component traits in both indica and japonica sets, and also low to intermediate between specific heterozygosity and heterosis in the indica set, whereas very little correlation was detected between heterosis and heterozygosity (either general or specific) in the japonica set. In comparison to the results from our previous studies, we concluded that the relationship between molecular marker heterozygosity and heterosis is variable, depending on the genetic materials used in the study, the diversity of rice germplasms and the complexity of the genetic basis of heterosis.

ERCC4 (XPF) encodes a human nucleotide excision repair protein with eukaryotic recombination homologs

ERCC4 is an essential human gene in the nucleotide excision repair (NER) pathway, which is responsible for removing UV-C photoproducts and bulky adducts from DNA. Among the NER genes, ERCC4 and ERCC1 are also uniquely involved in removing DNA interstrand cross-linking damage. The ERCC1-ERCC4 heterodimer, like the homologous Rad10-Rad1 complex, was recently found to possess an endonucleolytic activity that incises on the 5' side of damage. The ERCC4 gene, assigned to chromosome 16p13.1-p13.2, was previously isolated by using a chromosome 16 cosmid library. It corrects the defect in Chinese hamster ovary (CHO) mutants of NER complementation group 4 and is implicated in complementation group F of the human disorder xeroderma pigmentosum. We describe the ERCC4 gene structure and functional cDNA sequence encoding a 916-amino-acid protein (104 kDa), which has substantial homology with the eukaryotic DNA repair and recombination proteins MEI-9 (Drosophila melanogaster), Rad16 (Schizosaccharomyces pombe), and Rad1 (Saccharomyces cerevisiae). ERCC4 cDNA efficiently corrected mutants in rodent NER complementation groups 4 and 11, showing the equivalence of these groups, and ERCC4 protein levels were reduced in mutants of both groups. In cells of an XP-F patient, the ERCC4 protein level was reduced to less than 5%, consistent with XPF being the ERCC4 gene. The considerable identity (40%) between ERCC4 and MEI-9 suggests a possible involvement of ERCC4 in meiosis. In baboon tissues, ERCC4 was expressed weakly and was not significantly higher in testis than in nonmeiotic tissues.

[Experimental analysis of the calcium source for cardiac excitation-contraction coupling in hibernator Citellus dauricus]

The force-interval and force-frequency relationships and the effects of Cd2+ and ryanodine on the myocardial action potential and contraction were compared between hibernating (HGS) and active (AGS) ground squirrels Citellus dauricus. (1) Raising the driving frequency caused a negative inotropic effect in the AGS group, but a biphasic change with an increase of the peak force followed by a decrease in the HGS group. The contraction in HGS group exhibited a more pronounced post-interval potentiation, and was more significantly modulated by the driving frequency. (2) HGS animals displaged action potentials of shorter early-stage duration and stronger contractions of shorter time course in comparison with the AGS animals. Both the action potential and the contraction of HGS group were less affected by Cd2+, but the contraction was more significantly inhibited by ryanodine than that of the AGS group. Our results suggested that dependence of cardiac excitation-contraction coupling on calcium influx was weakened, while the function of sarcoplasmic reticulum as a source of activator Ca2+ was enhanced during hibernation, which might take an important part in the cold-tolerant adaptation of hibernating hearts.

Expression of the DNA repair gene XRCC1 in baboon tissues

XRCC1 is a DNA repair gene involved in rejoining DNA strand-breaks. We used baboon as an animal model to determine the levels of XRCC1 gene expression in different tissues. Baboons were selected because they are evolutionarily closely related to humans. A single 2.2 kb transcript was detected in all tissues tested by northern blot analysis, with variations in levels of expression among tissues. The expression levels of XRCC1 were measured by quantitative RNase protection assays. XRCC1 mRNA levels were significantly higher in testis than those in other tissues. A mean value of 24.6 x 10(5) XRCC1 transcripts per micrograms DNA was found in testis, while 10.5 x 10(5) in ovary, 9.8 x 10(5) in brain, 8.5 x 10(5) in liver, 6.8 x 10(5) in kidney, 6.5 x 10(5) in heart, 6.4 x 10(5) in lymph nodes, 6.0 x 10(5) in lung and 4.9 x 10(5) in spleen were found.

[Seasonal variation in the ultrastructure and calcium uptake rate of cardiac sarcoplasmic reticulum in ground sqirrel]

The ultrastructure and calcium uptake rate of the cardiac sarcoplasmic reticulum (SR) was quantatively compared between the ground squirrels (Citellus dauricus) in hibernating and non-hibernating season. (1) In our ultrastructural investigation, OsFeCN post-fixation method was used to enhance the staining of SR, which made the SR structure more recognizable. (2) The results of morphometrical analysis demonstrated that the volume density of SR and lipid droplet in the cardio-myocyte was significantly higher (P < 0.01) in the hibernating animal than in the summer active one, and the subcompartment of SR with this difference was non-junctional SR. (3) The cardiac SR from hibernating ground squirrels had a higher (P < 0.01) calcium uptake rate as measured by the absorbence of arsenazo-III Ca2+ indicator, than that from autumn active ones. Altogether, our results suggested that the function of SR in the uptake of cytosolic calcium was enhanced in hibernating season, which may play an important role in the cold tolerance of myocardium of a hibernator.

Testis and somatic Xrcc-1 DNA repair gene expression

The human XRCC1 gene has been shown to be involved in DNA strand-break repair using the Chinese hamster ovary cell mutant EM9. The purpose of this study was to characterize the expression of Xrcc-1 to determine if there is tissue-specific expression and to provide a baseline of information for future studies that may involve altering Xrcc-1 expression in mice. Normal young adult male testis and enriched populations of pachytene spermatocytes and round spermatids displayed significantly higher levels of Xrcc-1 expression than other mouse tissues, although Xrcc-1 transcripts were found in low abundance in all tested tissues. Cultured mouse cell lines displayed levels of expression similar to male germ cells, which is a striking contrast to the levels of expression obtained in somatic tissues from the mouse. The relatively high levels of expression identified in male germ cells indicate Xrcc-1 may have an important role in male germ cell physiology.

Cardiac mechanical restitution in active and hibernating Richardson's ground squirrel

The cardiac mechanical restitution was compared in papillary muscles between the active and the hibernating Richardson's ground squirrels at 0.1, 2.8, and 5 mM external Ca2+ concentration [( Ca2+]o). The amplitude of the restitution was significantly higher in hibernating animals between 37 and 7 degrees C at all [Ca2+]o. The first postrest contraction (F1) was highest at 20 degrees C and lower at 37 and 7 degrees C in both groups. The pause duration for maximum F1 was 30 s in active but 10 s in hibernating animals at 37 degrees C and increased to 100 s in both groups at 7 degrees C. The postrest potentiation was eliminated by 10(-6) M ryanodine at 20 degrees C in both groups, and this inhibitory effect was more pronounced in the hibernating group. Together, our results suggest that the activator Ca2+ for excitation-contraction coupling is mainly derived from the sarcoplasmic reticulum (SR) pool in both active and hibernating ground squirrel, and the dependence on SR Ca2+ release via ryanodine-sensitive Ca2+ channels is more marked in the hibernating state. Furthermore, there is no significant difference in sensitivity of the cardiac mechanical restitution to [Ca2+]o between the active and the hibernating condition.

A simple and easy-to-assemble device for polymerase chain reaction

In this paper we describe an efficient polymerase chain reaction device which is easy to assemble and requires minimal investment in dedicated equipment. The polymerase chain reaction device consists of three waterbaths, three dual-head peristaltic pumps, an electronic timer and a fabricated water jacket capable of holding microcentrifuge tubes. This device has been successfully used to amplify human factor X genomic DNA in our laboratory.

Molecular characterization of human factor XSan Antonio

Enzymatic amplification technique was used to isolate all eight exons and sequences around the splice junctions, putative promoter, and polyadenylation sites of human factor X DNA from a patient with factor X deficiency. Two genetic changes in factor X have been observed in this patient. The patient is most likely a compound heterozygote since there is only 14% activity associated with factor X. A point mutation that resulted in the substitution of cysteine (TGC) for arginine (CGC) at amino acid 366 was found in exon VIII of one allele of the factor X gene. This mutation, which occurs in the catalytic domain, can affect the formation of a disulfide bridge and thus could result in a reduction in factor X activity. Sequencing all the regions revealed a second mutation: a deletion of one nucleotide (TCCT to TCT) in exon VII that would cause a frame shift at amino acid 272 followed by termination. We have also shown that the point mutation in exon VIII creates an ApaL1 restriction site and destroys the HinP1 site. Enzymatic DNA amplification followed by restriction digestion provides a quick, reliable, and sensitive method for carrier detection and antenatal diagnosis in affected kindreds. This is the first characterization of factor X deficiency at the molecular level. We propose to name this mutation Factor XSan Antonio.

Differential effects of cooling in hibernator and nonhibernator cells: Na permeation

Unidirectional Na influx is less inhibited by cooling in guinea pig red blood cells than in ground squirrel cells. To isolate the source of this difference, component pathways of 24Na entry were estimated by use of selective inhibitors (ouabain, bumetanide, amiloride). Amiloride slightly inhibited influx in ground squirrel cells at every temperature between 37 and 5 degrees C. Amiloride did not consistently inhibit Na influx at 37 degrees C in guinea pig cells but caused a 44% inhibition at 25 degrees C and a 35% inhibition at 5 degrees C. Cytoplasmic acidification caused an increase in amiloride-sensitive influx in guinea pig cells, which was greater at 20 degrees C than at 37 degrees C; cytoplasmic acidification decreased amiloride-sensitive Na influx in ground squirrel cells at 37 degrees C and had no effect at 20 degrees C.