CFD-based pesticide selection for a nozzle used in a six-rotor UAV in hover mode for tea spraying

BACKGROUND

A key challenge for unmanned aerial vehicle (UAV) spraying sometimes used in tea plantations is the downwash flow structure there stronger than in crops. In addition, the UAV spray is affected by the relationship between the nozzle design and the pesticide. However, there is little current research on this aspect. As a preliminary step this study focuses on the most appropriate pesticide for a designated nozzle in a six-rotor UAV according to the nozzle-pesticide relationship using a three-dimensional computational fluid dynamics model. This model considers the downwash flow structure effect and nozzle spray performance in hover. Nozzle FVP110-02, widely used in six-rotor UAVs, is used as a representative nozzle and bifenthrin and tea saponin water, commonly used in tea plantations, are used as the pesticides.

RESULTS

The downwash flow structure of the six-rotor UAV in hover was conveniently controlled by the flight height and rotational speed, thereby causing the turbulence to be more stable. For nozzle FVP110-02, bifenthrin was more appropriate than tea saponin water at the same concentration, whilst bifenthrin and tea saponin water at a concentration of 1:1000 showed the best performance under identical working conditions.

CONCLUSION

The numerical model developed here was shown to be effective for investigating the relationship between nozzle and pesticide. Our findings will help to not only improve UAV spraying for tea cultivation but also provide guidelines for pesticide selection in crops. Further work will address the comparison of the rigorous qualification of the numerical simulations with the measurements by the field test. © 2023 Society of Chemical Industry.

[Analysis of typing conversion and perinatal outcomes in twins with selective intrauterine growth restriction of different subtypes]

Objective: To retrospectively analyze the clinical data of different types of selective intrauterine growth restriction (sIUGR) pregnant women under expectant management, including the natural evolution, typing conversion and perinatal outcomes. Methods: The clinical data of 153 pregnant women with sIUGR under expected treatment in Women's Hospital, Zhejiang University School of Medicine from January 2014 to December 2018 were collected. Maternal characteristics including maternal age, gravidity, parity, method of conception, pregnancy complication, gestational age at delivery, indication for delivery, birth weight, the rate of intrauterine and neonatal death and neonatal outcomes were recorded. Pregnant women with sIUGR were divided into three types according to end-diastolic umbilical artery flow Doppler ultrasonography, and the differences of typing conversion and perinatal outcomes of sIUGR pregnant women based on the first diagnosis were compared. Results: (1) Clinical characteristics and pregnancy outcomes: among 153 pregnant women with sIUGR, 100 cases (65.3%) were diagnosed with type Ⅰ, 35 cases (22.9%) with type Ⅱ, and 18 cases (11.8%) with type Ⅲ. There were no significant differences in age, conception mode, pregnancy complications, first diagnosis gestational age, characteristics of umbilical cord insertion, delivery indications, fetal intrauterine mortality and neonatal mortality among three types of sIUGR pregnant women (all P>0.05). The average gestational age at delivery of type Ⅰ sIUGR was (33.5±1.9) weeks, which was significantly later than those of type Ⅱ and Ⅲ [(31.3±1.8), (31.2±1.1) weeks, P<0.001]. The percentage disordance in estimated fetal weight (EFW) of type Ⅰ sIUGR was significantly lower than those of type Ⅱ and type Ⅲ (P<0.001). The incidence rate of neonatal intensive care unit (NICU) admission, cerebral leukomalacia and respiratory complications of both fetus and necrotizing enterocolitis of large fetus in type Ⅰ were significantly lower than those in type Ⅱ and type Ⅲ (all P<0.05). (2) Typing conversion: in 100 cases of type Ⅰ sIUGR, 18 cases progressed to type Ⅱ and 10 cases progressed to type Ⅲ. Compared with 72 stable type Ⅰ sIUGR, those with progressed type Ⅰ sIUGR had higher incidence of NICU admission and lung disease in both fetuses, and cerebral leukomalacia and necrotizing enterocolitis in large fetus (all P<0.05). The proportion of inconsistent cord insertion was significantly higher in those type Ⅰ progressed to type Ⅲ (6/10) than in those with stable type Ⅰ (19.4%, 14/72) and type Ⅰ progressed to type Ⅱ sIUGR [0 (0/18), P=0.001]. Four cases of type Ⅱ sIUGR reversed to type Ⅰ and 6 cases reversed to type Ⅲ. Compared with type Ⅱ reversed to type Ⅰ sIUGR, those stable type Ⅱ and type Ⅱ reversed to type Ⅲ sIUGR had a higher incidence of NICU admission in large fetus (P<0.05). Two cases of type Ⅲ sIUGR reversed to type Ⅰ and 6 cases progressed to type Ⅱ. There were no significant differences in fetal serious complications in type Ⅲ sIUGR with or without doppler changes (all P>0.05). Conclusions: The different types of sIUGR could convert to each other. The frequency of ultrasound examinations should be increased for patients with the type Ⅰ sIUGR, especially when the percentage discordance in EFW is substantial or with discordant cord insersion.

[Complicated lymphatic anomaly: a clinicopathological analysis of four cases]

Objective: To investigate the clinicopathological features, clinical manifestations and different diagnosis of patients with complicated lymphatic anomaly. Methods: The clinical and pathologic data of four patients with complicated lymphatic anomaly diagnosed and treated in Peking Union Medical College Hospital from January 2000 to December 2021 were collected and analyzed. Results: One Gorham-Stout disease case and three generalized lymphatic anomaly cases were included in this cohort. Patients' ages ranged from 7 to 32 years. There were three males and one female. The positions of biopsy included three bone biopsy and one bronchus biopsy. Microscopically, all cases showed diffuse enlarged lymphatic channels. At the same time, osteogenesis was obvious in Gorham-Stout disease case. Radiologically, cortical loss was seen in Gorham-Stout disease, and lytic bone confined to the medullary cavity presented in generalized lymphatic anomaly. The three generalized lymphatic anomaly cases also had coagulopathy, and two had effusion. Conclusions: The histologic feature of complicated lymphatic anomaly was diffuse lymphatic malformation, and the diagnosis depends on clinical and pathologic information. The treatment and prognosis of these diseases are different, and therefore it is necessary to understand their clinical and pathologic features and make the correct diagnosis.

The structural, mechanical and electronic properties of Ti-Al-based compounds by first-principles calculations

The first-principles calculations with density functional theory were performed to investigate the effects of transition metal elements (Mo, Cu, Fe, Ni and Nb) on the physical properties of the Ti-Al-based compounds. Our optimized crystal parameters are in good agreement with the previous theoretical and experimental values. The mechanical stability is verified by the independent elastic constants. The B/G and Poisson's ratio ν both show that Al₆TiMo is brittle, while other compounds exhibit ductility. The values of compression anisotropy of the compounds are small, but the shear anisotropy of AlCu₂Ti and AlNi₂Ti is much more intense than that of other compounds. The anisotropy in elastic properties of AlFe₂Ti and AlNbTi₂ is smaller than that of the others. It can be seen that the capacity to compress along c-axis is smaller than that along a-axis and b-axis for AlNbTi₂. For AlNbTi₂, the anisotropy of the bulk modulus along a-axis relative to b-axis is more insignificant than that along c-axis relative to b-axis. The hardness and Debye temperature verify that AlFe₂Ti has the greatest resistance to the plastic deformation and more intense inter-atomic bonding force, respectively. Band structures and DOS are used to investigate the electronic properties. The band structures without band gaps show that these ternary Ti-Al-based compounds are conductors. DOS shows the interactions between elements and gives the bond properties. Density of states and charge density both show the strong covalent properties of AlFe₂Ti by the hybridization between Fe-3d and Ti-3d states.

Gene expression and methylation profiles show the involvement of POMC in primary hyperparathyroidsm

Primary hyperparathyroidism (PHPT) is mainly caused by parathyroid adenoma, which produces excess parathyroid hormones. Its pathogenic mechanisms have not yet been fully understood. To investigate the mechanism in the pathogenesis of PHPT, the transcriptome and genome-wide DNA methylation profiles of parathyroid adenoma were analyzed. The candidate genes that may be involved in the PHPT were verified via qRT-PCR, immunohistochemistry, western blot, and methylation-specific PCR. A total of 1650 differentially expressed genes and 2373 differentially methylated regions were identified. After the integration of its transcriptome and DNA methylation data, IL6, SYP, GNA01, and pro-opiomelanocortin (POMC) were the candidate genes that demonstrated a similar pattern between their mRNA expression and DNA methylation status. Of the 4 candidate genes, POMC, a pro-peptide which is processed to a range of bioactive peptide products like ACTH, was further confirmed to be expressed at low levels at both the mRNA and protein levels, which may be due to POMC promoter hypermethylation. Hypermethylation of the POMC promoter may contribute to its low expression, which may be involved in the pathogenesis of PHPT.

[Consideration of diagnosing extremely well differentiated adenocarcinoma of gastrointestinal tract]

For gastrointestinal adenocarcinoma with excellent differentiation, some diagnostic names have emerged in recent years, which have overlapping and different meanings. Low-grade well differentiated adenocarcinoma and very well differentiated adenocarcinoma are terms for a group of adenocarcinomas with good differentiation and little cellular atypia, including a variety of histological types. It is suggested that specific histological types should be listed as far as possible in diagnosis, instead of using "low-grade well differentiated adenocarcinoma" or "very well differentiated adenocarcinoma" as a complete diagnosis. This kind of adenocarcinomas may lack cellular pleomorphism, so it is necessary to observe the structural atypia for diagnosis. At the same time, attention should be paid to the differentiation of reactive changes, low grade dysplasia, epithelial misplacement and other lesions.

[Prenatal diagnosis and prognostic factors analysis of fetal sacrococcygeal teratoma]

Objective: To investigate the prenatal diagnosis and prognostic factors of fetal sacrococcygeal teratoma (SCT). Methods: A retrospective analysis was performed on 41 pregnant women who were diagnosed with fetal SCT by prenatal ultrasound at the Women's Hospital, Zhejiang University School of Medicine from January 2014 to September 2021. The prenatal imaging features and pregnancy outcomes, including tumor volume to fetal weight ratio (TFR), proportion of solid tumor, tumor growth rate (TGR), fetal hydrops, placentomegaly and polyhydramnios were analyzed. Receiver operating characteristic (ROC) curve was used to determine the critical values of TFR and TGR for predicting adverse fetal outcomes. Results: (1) Among the 41 pregnant women with fetal SCT, the diagnostic gestational week of ultrasound was (24.2±2.9) weeks (range: 18-28 weeks). Among them, 1 case progressed to fetal hydrops and induced labor at 22 weeks of gestation, 1 case developed intrauterine death and induced labor at 29 weeks of gestation, and 39 pregnancies continued until delivery. Among the 39 cases of continued pregnancy, 1 case underwent cesarean section at 31 weeks of gestation due to malignant polyhydramnios and increased fetal cardiothoracic ratio in the third trimester, 1 case underwent cesarean section at 32 weeks of gestation due to fetal heart failure, and 1 case underwent cesarean section at 32 weeks of gestation due to fetal heart failure and hydrops. The other 36 cases underwent surgical resection of tumor within 3 weeks after birth with good prognosis. (2) TFR>0.12 before 28 weeks of gestation could predict poor fetal prognosis, with a sensitivity of 100.0%, a specificity of 86.1% and an area under curve (AUC) of 0.922 (P<0.01). Among the fetuses with TFR>0.12, 5/10 had poor prognosis, while the fetuses with TFR≤0.12 all had good prognosis (100%,31/31), and the difference between the two groups was statistically significant (P<0.001). (3) TGR>48 cm³/week could predict poor fetal prognosis with a sensitivity of 100.0%, a specificity of 78.3% and an AUC of 0.880 (P<0.05). (4) Among the 28 SCT fetuses delivered in our hospital, the incidence rate of poor fetal prognosis was 0 (0/20) in those with solid tumor component<50%, and 5/8 in those with solid tumor component ≥50%, and the difference between the two groups was statistically significant (P<0.01). The incidence rate of poor fetal prognosis was 2/2 in those with placentomegaly (all with fetal hydrops), and 12% (3/26) in those without placentomegaly. The risk of poor fetal prognosis was 8.67 times higher in those with placentomegaly than those without placentomegaly, and the difference between the two groups was statistically significant (P<0.05). The incidence rate of poor fetal prognosis in those with polyhydramnios was 3/7, and 10% (2/21) in those without polyhydramnios, but there was no statistically significant difference between the two groups (P>0.05). Conclusion: TFR combined with solid tumor morphology, TGR, and presence of placentomegaly could predict the adverse pregnancy outcomes of fetal SCT.

[Preliminary clinical experience of the novel transcatheter aortic valve system Prizvalve® for the treatment of severe aortic stenosis]

Objective: To evaluate the safety and efficacy of transcatheter aortic valve implantation (TAVI) with the novel Prizvalve^® system in treating severe aortic stenosis. Methods: This is a single-center, prospective, single-arm, observational study. A total of 11 patients with severe aortic stenosis with high risk or inappropriate for conventional surgical aortic valve replacement (SAVR) were included, and TAVI was achieved with the Prizvalve^® system between March 2021 and May 2021 in West China Hospital. Transthoracic echocardiography (TTE) was performed immediately after prosthesis implantation to evaluate mean transaortic gradient and maximal transaortic velocity. The device success rate was calculated, which was defined as (1) the device being delivered via the access, deployed, implanted and withdrawn, (2) mean transaortic gradient<20 mmHg (1 mmHg=0.133 kPa) or a maximal transaortic velocity<3 m/s post TAVI, and without severe aortic regurgitation or paravalvular leak post TAVI. TTE was performed at 30 days after the surgery, and all-cause mortality as well as the major cardiovascular adverse events (including acute myocardial infarction, disabling hemorrhagic or ischemic stroke) up to 30 days post TAVI were analyzed. Results: The age of 11 included patients were (78.1±6.3) years, with 8 males. A total of 10 patients were with NYHA functional class Ⅲ or Ⅳ. Devices were delivered via the access, deployed, implanted and withdrawn successfully in all patients. Post-implant mean transaortic gradient was (7.55±4.08) mmHg and maximal transaortic velocity was (1.78±0.44) m/s, and both decreased significantly as compared to baseline levels (both P<0.05). No severe aortic regurgitation or paravalvular leak was observed post TAVI. Device success was achieved in all the 11 patients. No patient died or experienced major cardiovascular adverse events up to 30 days post TAVI. Mean transaortic gradient was (9.45±5.07) mmHg and maximal transaortic velocity was (2.05±0.42) m/s at 30 days post TAVI, which were similar as the values measured immediately post TAVI (both P>0.05). Conclusions: TAVI with the Prizvalve^® system is a feasible and relatively safe procedure for patients with severe aortic stenosis and at high risk or inappropriate for SAVR. Further clinical studies could be launched to obtain more clinical experience with Prizvalve^® system.

[Analysis of molecular and clinical characteristics of carbapenem-resistant hypervirulent Klebsiella pneumoniae in the intensive care unit]

To investigate the carbapenemases distribution of carbapenem-resistant Klebsiella pneumoniae (CRKP) in the intensive care unit, and the clinical characteristics between carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) and carbapenem-resistant non-hypervirulent Klebsiella pneumoniae (CR-non-hvKP) were compared. A total of 53 non-repetitive CRKP strains isolated from 49 patients in the intensive care unit of the Second Affiliated Hospital of Xi'an Jiaotong University from May 2020 to March 2021 were retrospectively studied. The carbapenemase inhibitor enhancement test was used for screening carbapenemase-producing strains, and the string test was carried out to screen the hypermucoviscosity phenotype. Using PCR to detect five main carbapenemase genes (bla_KPC-2, bla_NDM, bla_IMP , bla_VIM and bla_OXA-48-like), common serotype (K1 and K2) and virulence gene (rmpA and iutA). Treated the strains with both rmpA and iutA genes as hypervirulent Klebsiella pneumonia (hvKP), and the whole genome sequencing of CR-hvKP was completed. At the same time, the clinical data of 49 patients were sorted out, and the differences in clinical characteristics of CR-hvKP and CR-non-hvKP infected patients were compared using the independent sample t test, Mann-Whitney U test, chi-square test or Fisher's exact probability test. CRKP isolated from the intensive care unit were extensively drug resistance and still had a good sensitivity to polymyxin B and tigecycline. Producing carbapenemases were the main resistance mechanism of CRKP (52/53, 98.1%). Of the 53 CRKP strains, except for 1strain that did not detect carbapenemase, at least one carbapenemase resistance gene was detected in the remaining 52 CRKP strains, of which 45 strains carried an enzyme, including 36 bla_KPC-2 (36/53, 67.9%), 8 bla_NDM (8/53, 15.1%), 1 bla_IMP (1/53, 1.9%), and 7 strains carried with both bla_KPC-2 and bla_NDM (7/53, 13.2%). String test and virulence gene showed that 7 CR-hvKP strains (13.2%) were detected in 53 CRKP strains, and two of which were hypermucoviscosity phenotype. Sequencing results revealed that CR-hvKP were mainly ST11 type. Almost all patients with CR-hvKP infection were over 60 years old (7/7), with invasive treatment (7/7), pulmonary infection with hypermucoviscosity phenotype (2/7) and high mortality (5/7); and the percentage of neutrophils in patients with CR-hvKP infection (86.44±4.70) % was higher than those patients with CR-non-hvKP infection (78.90±19.15) %, the difference was statistically significant (t=-2.225, P=0.032). The CR-hvKP strains in the intensive care unit mainly produced KPC-2 enzyme, with K2 capsular serotype and ST11 type. It is necessary to strengthen the monitoring and control of the CR-hvKP strain to prevent the co-evolution of drug-resistant and hypervirulent strains.

[Clinical features and perinatal outcomes of 48 cases of pregnancy complicated with placental cystic lesions]

Objective: To investigate the clinical characteristics and perinatal outcomes of pregnancy with placental cystic lesions. Methods: A retrospective study was carried out on 48 pregnant women diagnosed as pregnancy complicated with placental cystic lesions from January 2000 to January 2020 at the Women's Hospital, Zhejiang University School of Medicine. The clinical features, pathological diagnosis and perinatal outcome were analyzed. Results: The age of 48 cases was (30±5) years, and the diagnostic gestational week of ultrasound was (24±8) weeks. Twenty-five cases in which showed a cystic mass at the fetal surface were diagnosed as placental cyst. The live birth rate was 100% (25/25) and the premature birth rate was 20% (5/25). Twenty-three cases showed "honeycomb like" cystic echo. Cystic lesions of 10 cases were located in the uterine cavity connected with the margin of the normal placenta, and finally diagnosed as hydatidiform mole and coexisting fetus (HMCF). Six cases of HMCF terminated pregnancy, and the live birth rate was 4/10, the premature delivery rate was 2/4. Cystic lesions of 13 cases were located in the placenta substance, and finally diagnosed as 4 cases of placental mesenchymal dysplasia (PMD) and 9 cases of focal chorionic edema; the live birth rate was 6/13 and the premature delivery rate was 4/6. The median hCG was lower in focal chorionic edema group [80 kU/L (60-110 kU/L)] than in the groups of HMCF [240 kU/L (180-430 kU/L)] and PMD [360 kU/L (210-700 kU/L)], and the differences were statistically significant (all P<0.01). Conclusions: For pregnancy complicated with placental cystic lesions, prenatal ultrasound should be performed to evaluate the shape, location and blood flow of the lesions. Maternal serological examination and invasive prenatal diagnosis are helpful for prenatal diagnosis and treatment. Due to the difference of perinatal outcomes, maternal and fetal complications, individualized pregnancy management should be carried out.

Dysbiosis of intestinal microbiota in early life aggravates high-fat diet induced dysmetabolism in adult mice

BACKGROUND

Accumulating evidence have shown that the intestinal microbiota plays an important role in prevention of host obesity and metabolism disorders. Recent studies also demonstrate that early life is the key time for the colonization of intestinal microbes in host. However, there are few studies focusing on possible association between intestinal microbiota in the early life and metabolism in adulthood. Therefore the present study was conducted to examine whether the short term antibiotic and/or probiotic exposure in early life could affect intestinal microbes and their possible long term effects on host metabolism.

RESULTS

A high-fat diet resulted in glucose and lipid metabolism disorders with higher levels of visceral fat rate, insulin-resistance indices, and leptin. Exposure to ceftriaxone in early life aggravated the negative influences of a high-fat diet on mouse physiology. Orally fed TMC3115 protected mice, especially those who had received treatment throughout the whole study, from damage due to a high-fat diet, such as increases in levels of fasting blood glucose and serum levels of insulin, leptin, and IR indices. Exposure to ceftriaxone during the first 2 weeks of life was linked to dysbiosis of the fecal microbiota with a significant decrease in the species richness and diversity. However, the influence of orally fed ceftriaxone on the fecal microbiota was limited to 12 weeks after the termination of treatment. Of note, at week 12 there were still some differences in the composition of intestinal microbiota between mice provided with high fat diet and antibiotic exposure and those only fed a high fat diet.

CONCLUSIONS

These results indicated that exposure to antibiotics, such as ceftriaxone, in early life may aggravate the negative influences of a high-fat diet on the physiology of the host animal. These results also suggest that the crosstalk between the host and their intestinal microbiota in early life may be more important than that in adulthood, even though the same intestinal microbes are present in adulthood.

[Clinical and genetic characteristics of patients with chronic enteropathy associated with SLCO2A1 gene]

Objective: To determine the clinical features and genetic characters of patients with chronic enteropathy associated SLCO2A1 gene (CEAS). Methods: Five CEAS patients diagnosed at Peking Union Medical College Hospital from January 2012 to December 2019 were enrolled in this study. The clinical manifestations, laboratory test, radiological and endoscopic findings, gene detections, treatments and prognosis of these patients were reviewed and analyzed. Results: Five male patients presented gastrointestinal symptoms after puberty, including abdominal pain, diarrhea, intermittent melena or hematochezia, incomplete bowel obstruction, anemia, hypoalbuminemia and hypokalemia. The whole gastrointestinal tract except esophagus could be involved, especially the stomach and ileum. Intestinal lesions were characterized by multiple shallow ulcers with stenosis in the layers of mucosa and submucosa. Five patients were all accompanied with primary hypertrophic osteoarthropathy (PHO), and 1 with myelofibrosis and thoracic duct dysplasia. All patients were homozygous or compound heterozygous mutations of SLCO2A1 gene. Conventional treatment of inflammatory bowel disease and COX-2 inhibitors were ineffective. Conclusions: CEAS is an autosomal recessive genetic disease which widely involves the gastrointestinal tract, and can be associated with skin and bone involvement. There is no effective treatment for CEAS at present. CEAS is a different entity from other inflammatory gastrointestinal diseases.

[Clinical characteristics and microbiome analysis in patients with anti-programmed cell death protein 1 related colitis]

Objective: To analyze clinical characteristics and monitor microbiome changes in patients with anti-PD-1 associated colitis. Methods: Two patients with non-small cell lung cancer who developed colitis after treated with anti-PD-1 antibodies were retrospectively analyzed in Peking Union Medical College Hospital from January 2019 to January 2020. The clinical symptoms, endoscopic and pathological manifestations, as well microbiome changes were analyzed and compared during pre-treatment, post-treatment and relapse. Results: The main clinical manifestations included diarrhea, elevated inflammatory indicators, colonic mucosal diffuse hyperemic edema with erosion by endoscopy. Changes in the structure of crypts were common pathological characteristics. Glucocorticoids were effective agents, which achieved clinical remission and mucosal healing. The microbiome composition of OTUs was different. After glucocorticoid treatment, the alpha diversity Observed species, Shannon, Simpson, Chao1, ACE indexes all decreased. The Firmicutes decreased with Bacteroidetes increasing in phylum level; while the Bacteroides increased with Ruminococcaceae decreasing in genus level. Lactobacillus was the potentially beneficial genus. Conclusion: Patients developing anti-PD-1 associated colitis have characteristic clinical and pathological manifestations. Glucocorticoids are effective treatment. The fecal microbiome diversity, relative abundance of major phylum and genus have changed after treatment.

[Endoscopic features and clinical correlation analysis of 24 patients with Cronkhite-Canada syndrome]

Objective: To clarify the endoscopic changes prior to corticosteroid therapy in Cronkhite-Canada syndrome (CCS) patients and to explore the correlation between endoscopic features and clinical characteristics. Methods: A total of 24 CCS patients who were hospitalized in Peking Union Medical College Hospital from January 1999 to June 2019 and underwent gastroscopy and colonoscopy before corticosteroid therapy were retrospectively enrolled. The endoscopic images were re-interpreted. The demographic characteristics, clinical manifestations, laboratory tests and histopathological data were collected and analyzed. Results: Of all 24 patients, 15 (62.5%) were male and 9(37.5%) were female, with an average age of (59±10) years and disease course of 6 (1~36) months. Based on the endoscopic findings, the percentages of stomach, colon, duodenum, rectum and terminal ileum involvement were 100%, 100%, 95.7%, 66.7% and 50.0% respectively. Gastric involvement was more severe in the lower part of the body and the antrum of the stomach, while the cardia and the fundus were spared in 5 (20.8%) cases. Colonic involvement was more severe in the right colon. No patient showed remarkable esophageal involvement. The typical appearance under endoscopy were diffuse mucosal hyperemia and edema with polyps or nodular changes. The lesions may have mulberry-like or imbricate changes in severe cases. Lymphatic dilation in the duodenum was found in 47.8% patients. Most of the polyps were pedunculated or sub-pedunculated, with occasionally seen sessile polyps in the colon. The pit patterns of the 12 resected colon polyps in 11 patients could be classified as Kudo type Ⅲ(S), Ⅲ(L), Ⅳ and Ⅴ(I), among which 2 tubular adenomas had the Kudo type Ⅲ(L). Other resected polyps were hyperplastic polyps or CCS polyps. The disease duration prior to diagnosis was positively correlated with the maximum diameter of colon polyps (r=0.625, P=0.006). Serum albumin levels in patients with whole stomach involvement were significantly lower than those in patients with cardia spared [(29±8) g/L vs (37±5) g/L, P=0.034]. Conclusions: The typical initial endoscopic finding of CCS is multiple polyps or nodular changes on the background of diffuse hyperemia and edema lining the gastric, duodenal and colonic mucosa. Lymphatic dilatation in the duodenum could also be found. Some endoscopic features are correlated to clinical characteristics.

[Different viral doses of cytomegalovirus infection in the left and right colons]

Objective: To compare the differences in the detection rates of cytomegalovirus (CMV) infection between the left and right colons for guiding endoscopic biopsy-sites. Methods: The cases of colonic CMV infection confirmed by histology at the Peking Union Medical College Hospital from July 2015 to July 2018 were collected and analyzed. Splenic curvature was used as the dividing point between the left and right colons. The CMV inclusions were identified histologically, and the CMV infected cells were detected using immunohistochemistry (EnVision method). The numbers of infected cells in the left and right colons were compared by histological and immunohistochemical results. A total of 731 patients were identified. Ten of the 731 patients had histological specimens of both left and right colons and were confirmed with CMV EnVision immunohistochemical study. There were 25 biopsy or resection specimens. Seven patients were male and 3 were female, and their ages ranged from 29 to 66 years, with a median age of 55 years. All of the 10 patients were also diagnosed with ulcerative colitis. Results: The number of the cells infected with CMV in the left colon was 115 (1-41), while that in the right colon was 76 (0-51). In 8/10 cases, the number of CMV infected cells in the left colon was more than that in the right colon. Conclusions: The study on the biopsies and resection specimens suggests that CMV infection is mostly present in the left colon. The left colon thus might be an important endoscopic biopsy-site for the cases with suspicion of CMV infection.

[Analysis of influencing factors of endometrial disease of patients with breast cancer after operation]

Objective: To study influencing factors which cause the endometrial diseases in patients with breast cancer after operation. Methods: A retrospective study was performed on 212 breast cancer post-operation patients with endometrial diseases between June 2006 and January 2018 in Women's Hospital School of Medicine Zhejiang University to analyse the factors which influenced the endometrial diseases. Results: The abnormal uterine bleeding and endometrial thickness were related to the severity of endometrial disease in patients with breast cancer, and they were independent risk factors for breast cancer patients to have endometrial cancer (P<0.05) . When the diagnostic cut off value of endometrial thickness was ≥0.49 cm, the sensitivity and specificity to endometrial cancer were 78% and 25%, respectively. The average endometrial thickness was (0.56±0.39) cm in patients who were treated by selective estrogen receptor modulator (SERM) after gynecological surgery, which was significantly thicker than that of aromatase inhibitor (AI) group [ (0.33±0.23) cm] and no treatment group [ (0.44±0.28) cm, P<0.05]. The endometrial disease recurrent rate and reoperation rate in SERM group were (26.2%, 14.3%) slightly higher than that of AI group (9.5%, 4.8%) and no treatment group (21.6%, 4.9%), but there were not significant differences (all P>0.05). Conclusions: The clinical symptom of abnormal uterine bleeding and thickening endometrium are risk factors for breast cancer patients to have endometrial cancer. The endometrial thickness has high predictive value for breast cancer patients to diagnose endometrial cancer. The SERM treatment increases the endometrial thickness, recurrent rate and reoperation rate in post-operation patients.

[The 471st case: duodenal ulcer, mucor infection, and elevated IgG(4)]

Mucor infection is rarely reported in non-immunocompromised population, especially in isolated gastrointestinal tracts. IgG(4)-related diseases (IgG(4)-RD) have been recognized in recent years, but secondary causes of IgG(4) elevation should be differentiated. We reported a young man with duodenal mass and ulcer and high serum IgG(4) level. Histological biopsy of the mass revealed positive mucor mycelium and infiltration of IgG(4) positive plasma cells. Serum IgG(4) decreased to normal range after surgical resection and systemic antifungal treatment. This case suggests that isolated mucor mycosis infection can develop in the digestive tract and mimics as IgG(4)-related disease.

[The clinical characteristics of immunocompetent adults with chronic active Epstein-Barr virus associated enteritis]

Objective: To investigate the clinical and pathological characteristics of chronic active Epstein-Barr virus associated enteritis (CAEAE) . Methods: The clinical data of 6 CAEAE patients in Peking Union Medical College Hospital were retrospectively analyzed from January 2010 to November 2017, including clinical manifestations, endoscopic, pathological features, medications and clinical outcome. Results: The male∶female ratio was 4∶2 and the average age was 34 years old. All patients did not have personal and family history of immunodeficiency. The common symptoms consisted of fever (6/6), abdominal pain (6/6), hematochezia (6/6) and diarrhea (5/6). The most frequently affected sites were colorectum (5/6), followed by small intestine (3/6). Further serologic tests revealed a high load of serum Epstein-Barr virus(EBV) DNA. The main manifestations under endoscopy were multifocal or diffuse irregular ulcers. There was inflammation in the ulcer bases and surrounding areas, where EBV-encoded small RNA (EBER) was positive by in situ hybridization (6/6). The common complications were massive hemorrhage (3/6) and intestinal perforation (2/6). None of treatment agents including glucocorticoid, ganciclovir, foscarnet sodium and cytotoxic drugs was effective. All patients died within 0.5 to 13 months after diagnosis. Conclusions: CAEAE in immunocompetent individuals is a rare disorder with poor prognosis. It is difficult to differentiate CAEAE from inflammatory bowel disease due to similar clinical and endoscopic manifestations.

Oxygen Electromigration and Energy Band Reconstruction Induced by Electrolyte Field Effect at Oxide Interfaces

Electrolyte gating is a powerful means for tuning the carrier density and exploring the resultant modulation of novel properties on solid surfaces. However, the mechanism, especially its effect on the oxygen migration and electrostatic charging at the oxide heterostructures, is still unclear. Here we explore the electrolyte gating on oxygen-deficient interfaces between SrTiO_{3} (STO) crystals and LaAlO_{3} (LAO) overlayer through the measurements of electrical transport, x-ray absorption spectroscopy, and photoluminescence spectra. We found that oxygen vacancies (O_{vac}) were filled selectively and irreversibly after gating due to oxygen electromigration at the amorphous LAO/STO interface, resulting in a reconstruction of its interfacial band structure. Because of the filling of O_{vac}, the amorphous interface also showed an enhanced electron mobility and quantum oscillation of the conductance. Further, the filling effect could be controlled by the degree of the crystallinity of the LAO overlayer by varying the growth temperatures. Our results reveal the different effects induced by electrolyte gating, providing further clues to understand the mechanism of electrolyte gating on buried interfaces and also opening a new avenue for constructing high-mobility oxide interfaces.

[The 465th case: intestinal obstruction, gastrointestinal hemorrhage and duodenal fistula]

This is a complicated and difficult case. The onset symptom of a 62-year-old male was recurrent intestinal obstruction. Ileocecal and ileocolic operation was done twice. Massive gastrointestinal bleeding occurred due to giant fistula of descending duodenum, which connected to ileocolic anastomosis. After consultation by multidisciplinary team, jejunal-feeding tube was placed to provide enteral nutrition. With general condition improving, duodenal fistula repair and involved bowel resection were performed. Postoperative pathology confirmed Crohn's disease. The patient was treated with thalidomide and recovered well during follow-up.

[Clinicopathologic features of gastric adenocarcinoma based on the revised Lauren's classification]

Objective: To compare the clinicopathologic features and prognosis of the subtypes in a consecutive series of gastric cancers (GC) patients basing on the revised Lauren's classification so as to better understand the biological behavior of GC. Methods: The surgically resected GC from Peking Union Medical College Hospital during 2003-2005 were reviewed for patients' age, gender, tumor size, location, Borrman classification, depth of invasion, lymph node metastasis, vascular invasion, and tumor growth pattern (Ming classification). Results: One hundred and sixty-six GC cases were enrolled and classified into four groups: intestinal GC (30, 18.1%), diffuse GC (56, 33.7%), solid GC (9, 5.4%), and mixed GC (71, 42.8%). Intestinal GC patients were older[ (63.2±11.3) years], with a male predominance, and were more frequently found in the antrum. Intestinal GC was the most common subtype for early GC, and tend to develop liver metastases. Diffuse GC patients were youngest [(52.2±12.7) years], with no gender difference, and were usually found in the antrum. Microscopically, diffuse GC were more likely infiltrative (51/56, 91.1%), and tended to metastasize by lymphatic pathway. Solid GC were usually large[ (6.4±2.2) cm], with a male predominance, and the most frequent site was the body/fundus. Solid GC were more likely to show expansile growth pattern with greater depth of invasion (8 of 9 cases were T3/4), but lower rate of lymphatic metastasis. Mixed GC also showed a male predominance, usually found in the antrum, and showed an infiltrative growth pattern (49/71, 69.0%). Though there was fewer T3/4 than solid and diffuse GC, mixed GC were more likely to show lymph nodes, vascular metastases and liver metastases (13/71, 18.3%). TNM staging, lymph nodes metastasis, lymphovascular invasion and revised Lauren's classification were four independent prognostic factors on multivariate analysis(P<0.05). The survival of patients with mixed GC were significantly worse than patients with other histological types. Conclusion: Revised Lauren's classification for GC has four distinct subgroups and can be used as independent prognostic factors.

[Associations of sigmoid colon mucosal mast cells with bowel symptoms and psychological status in patients with irritable bowel syndrome with diarrhea]

OBJECTIVE

To investigate the bowel symptoms and psychological status of patients with irritable bowel syndrome (IBS) with diarrhea (IBS-D), and to verify whether sigmoid colon mucosal mast cells (MCs) and their activation have effect on the symptoms and psychological status of IBS-D patients.

METHODS

Patients meeting Rome Ⅲ diagnostic and subtyping criteria of IBS-D who visited the outpatient clinic of gastroenterology of Peking Union Medical College Hospital were consecutively enrolled between July 2009 and June 2012. IBS symptoms questionnaire was completed using face-to-face interview, and Hamilton Anxiety Scale (HAMA)/ Hamilton Depression Scale (HAMD) were administrated to evaluate psychological status, both by well-trained investigators. Mast cell tryptase monoclonal antibody was used for immunohistochemical staining to detect MCs and degranulated MCs in mucosal biopsy of sigmoid colon. MCs and degranulated MCs were blindly counted by a senior pathologist, and presented as number of cells in high power field (HPF) and percentage of activated MCs. Correlation analysis was performed using Spearman rank correlation analysis.

RESULTS

Ninety-seven patients with IBS-D were enrolled in this study, with mean age of (44±11) years. 70.10%(68 cases) of the IBS-D patients had comorbid anxiety and/or depression. The median total numbers of MCs, activated MCs, and percentage of activated MCs in sigmoid mucosa were 11.60 (7.09)/HPF, 2.00 (1.40) /HPF, and 17.50% (10.90%), respectively. Patients having abdominal pain/discomfort before bowel movement "every day with intermediate to high severity" had significantly larger numbers of total MCs in sigmoid colon compared with those with pain or discomfort "not every day and mild" [13.80(4.85)vs 7.60(5.90)/HPF, P=0.019]; the patient having "frequent" urge to have a bowel movement and mushy stools showed significantly higher percentage of activated MCs in sigmoid colon mucosa compared to those having the symptoms "some of the time" [18.75%(9.12%) vs 14.50%(13.14%), P=0.031; 21.33%(7.43%)vs 11.51%(10.65%)vs 18.42%(8.61%), P=0.030]. There was a positive correlation between the bowel movement during IBS-D onset and the percentage of activated MCs (r=0.221, P=0.030). There were no statistically significant differences in the total number of MCs and percentage of activated MCs between the patients with anxiety/depression and those without anxiety/depression (P=0.255, P=0.315). Scores of HAMA and HAMD were found not correlated with either total MCs number or percentage of activated MCs in sigmoid colon mucosa(all P>0.05).

CONCLUSIONS

The majority of IBS-D patients had comorbid anxiety and/or depression. The total number and activation status of MCs in sigmoid colon mucosa might be related with some intestinal symptoms in IBS-D patients. Psychological disorders might influence the pathogenesis and regression of IBS-D through brain-gut axis other than MCs in sigmoid colon mucosa.

[Rectal gastrointestinal stromal tumor: a clinical and pathologic analysis]

OBJECTIVE

To investigate the clinicopathologic characteristics and therapy of rectal gastrointestinal stromal tumors (GISTs).

METHODS

Clinical findings, morphologic features, immunophenotype and prognosis of 53 cases (58 samples) of rectal GISTs were investigated.

RESULTS

Thirty-three patients were male and 20 were female. The age of patients ranged from 19 to 81 years, with an average of 49.7 years. The main symptoms included rectal disorders in 29 patients and vaginal mass in 2 patients, while the tumors in 22 patients were found by routine physical examination. Thirty-five primary GISTs were resected completely without preoperative therapy, and thirteen tumors were resected after therapy of imatinib. Five tumors were recurrent. Imatinib therapy in 13 patients led to smaller and softer tumor mass grossly and decreased cellularity and marked degeneration histologically. Of the 35 primary rectal GISTs, there were 17 (48.6%), 6 (17.1%), 0(0), and 12 (34.3%) cases diagnosed as very low risk, low risk, medium risk, and high risk respectively. Eight cases had tumor of 1 cm or less in diameter. In the five recurrent cases, the tumors showed increased cellularity, mitotic figures, and Ki-67 index. Imatinib therapy led to smaller and softer tumor mass grossly and decreased cellularity and marked degeneration histologically. Immunohistochemical stains showed CD117, DOG1, and CD34 positivity, S-100 protein negativity and indefinite SMA stain.

CONCLUSIONS

Rectal GISTs are rare tumors with a male predominance.Patients without obvious sypmtoms are found by themselves and by routine physical examination. The tumor diameter less than 2 cm is common while larger than 5 cm is few. Diagnosis of rectal GISTs is easily made by biopsy and patients often acquire preoperative therapy for preserving anal sphincter function.

Proteomic data show an increase in autoantibodies and alpha-fetoprotein and a decrease in apolipoprotein A-II with time in sera from senescence-accelerated mice

We evaluated changes in levels by comparing serum proteins in senescence-accelerated mouse-prone 8 (SAMP8) mice at 2, 6, 12, and 15 months of age (SAMP8-2 m, -6 m, -12 m, -15 m) to age-matched SAM-resistant 1 (SAMR1) mice. Mice were sacrificed, and blood was analyzed by 2-dimensional electrophoresis combined with mass spectrometry. Five protein spots were present in all SAMP8 serum samples, but only appeared in SAMR1 samples at 15 months of age except for spot 3, which also showed a slight expression in SAMR1-12 m sera. Two proteins decreased in the sera from SAMP8-2 m, -6 m, and -12 m mice, and divided into 2 spots each in SAMP8-15 m sera. Thus, the total number of altered spots in SAMP8 sera was 7; of these, 4 were identified as Ig kappa chain V region (M-T413), chain A of an activity suppressing Fab fragment to cytochrome P450 aromatase (32C2_A), alpha-fetoprotein, and apolipoprotein A-II. M-T413 is a monoclonal CD4 antibody, which inhibits T cell proliferation. We found that M-T413 RNA level was significantly enhanced in splenocytes from SAMP8-2 m mice. This agreed with serum M-T413 protein alterations and a strikingly lower blood CD4⁺ T cell count in SAMP8 mice when compared to the age-matched SAMR1 mice, with the latter negatively correlating with serum M-T413 protein volume. Age-related changes in serum proteins favored an increase in autoantibodies and alpha-fetoprotein and a decrease of apolipoprotein A-II, which occurred in SAMP8 mice at 2 months of age and onwards. These proteins may serve as candidate biomarkers for early aging.

EGCG inhibits proliferation of cardiac fibroblasts in rats with cardiac hypertrophy

This study was carried out in order to investigate the effects of epigallocatechin gallate (EGCG) on myocardial fibrosis and cell proliferation in cardiac hypertrophy. Cardiac hypertrophy was established in rats by abdominal aortic constriction, and EGCG at doses of 25, 50 and 100 mg/kg was administered intragastrically for 6 weeks. The results showed that in the rats with cardiac hypertrophy, EGCG at 25 - 100 mg/kg dose-dependently reduced heart weight indices, decreased atrial natriuretic polypeptide and endothelin levels in plasma, but increased nitrite (the oxidative product of NO) levels in the serum and in the myocardium. EGCG also reduced the hydroxyproline concentration and decreased the proliferating cell nuclear antigen expression in the hypertrophic myocardium. EGCG remarkably inhibited pressure overload-induced c-myc increase in Western blot analysis. In cultured newborn rat cardiac fibroblasts, treatment with EGCG at 12.5 - 200 mg/L for 6 - 48 h decreased cell proliferation induced by serum. EGCG at 12.5 - 100 mg/L dose-dependently inhibited cell proliferation and DNA synthesis of fibroblasts induced by angiotensin II (Ang II) at 1 mumol/L. EGCG also significantly increased nitrite levels in culture medium, and up-regulated inducible nitric oxide synthase protein expression if compared with the Ang II group. The inhibitory effect of EGCG on cell proliferation induced by Ang II was partly blocked by pretreatment with N(omega)-nitro- L-arginine methyl ester hydrochloride. These results suggest that EGCG inhibits the proliferation of cardiac fibroblasts both in vivo and in vitro, thereby preventing myocardial fibrosis in cardiac hypertrophy. EGCG might exert its cardiac protective action through induction of NO production.

Effect of Astragalus complanatus flavonoid on anti-liver fibrosis in rats

AIM: To observe the anti-liver fibrosis effect of Astragalus complanatus flavonoids (ACF) in rats.

METHODS: The liver fibrosis model in rats was established by injecting interperitoneally 0.2 mL/100 g 0.5% dimethylnitrosamine, thrice a week. Meanwhile, the rats were administered ACF (30, 60, 120 mg/kg) or colchicine (0.1 mg/kg) once a day for 1 mo. Serum N-propeptide of type I procollagen (PINP) and type III procollagen (PIIINP) was measured using ELISA. Malondialdehyde (MDA) and superoxide dismutase (SOD) in hepatic tissue were evaluated. Matrix metal protease-1 (MMP-1) mRNA expression was assayed by RT-PCR and the protein expression of tissue inhibitor of metal protease-1 (TIMP-1) was analyzed by immunohistochemistry.

RESULTS: In the ACF groups, SOD activity increased and MDA content decreased in comparison to the liver fibrosis model group. The serum PINP and PIIINP contents in ACF-2 and -3 group decreased compared to those in model group. In ACF-2 and -3 group, the expression of MMP-1 mRNA increased significantly and the protein expression of TIMP-1 decreased compared to that in model group.

CONCLUSION: The antifibrotic mechanisms of ACF are associated with its influence on lipid peroxidation and collagen synthesis and degradation.

Large area UV casting using diverse polyacrylates of microchannels separated by high aspect ratio microwalls

Large area molding of long and deep microchannels separated by high aspect ratio microwalls is important for high sensitivity and high throughput microfluidic devices. Ultraviolet (UV) casting is a feasible, economical and convenient method of replication of such microstructures in plastics. It is shown that a wide variety of polyacrylates with diverse properties such as those made from epoxy (EP), polyurethane (UR), polyester (ES), poly (ethylene glycol) (EG) and poly(propylene glycol) (PG) can be used for the high aspect ratio (7-9) UV casting of such linear microstructures over a 100 mm diameter, enlarging the range of applications of the replicated microstructures. Some challenges arise. With the EG formulation, wavy microstructures were observed; this can be overcome by stress relaxation. With non-polar PG formulation, poor adhesion between the polyester substrate and resin can lead to delamination of the casting from the substrate during demolding; this can be overcome by pre-coating a partially cured same resin on the polyester substrate. An optimum UV irradiation time was important for cure at the deepest end of the microstructure without excessive crosslinking leading to much increased demolding forces. The viscosity and wetting capability of the formulations were found to affect replication fidelity.

Effects of xiaoyu tablet on endothelin-1, nitric oxide, and apoptotic cells of atherosclerotic vessel wall in rabbits

AIM

To investigate the mechanism of xiaoyu tablet on reduction of smooth muscle cells (SMC) in atherosclerotic vessel wall.

METHODS

The atherosclerotic model was performed in male New Zealand rabbits that were given high fat diet and abrasion of the abdominal aorta endothelial cells. The rabbits were then administered with xiaoyu tablet 0.16-0.32 g x kg(-1) x d(-1) for 16 weeks. Changes in morphology, endothelin (ET)-1, nitric oxide (NO), and apoptotic cells of atherosclerotic vessel wall were determined by the microscopy, radioimmunoassay, colorimetric method, the techniques of DNA in situ end labeling, and image pattern analysis, respectively.

RESULTS

After 16 weeks of xiaoyu tablet treatment, intimal thickness and SMC in atherosclerotic vessel wall were diminished, ET-1 was decreased by 8.2 %-42.6 %, NO was increased by 7.5 %-54.2 %, and labeled apoptotic nuclei were markedly decreased, the area and integral optical density of positive granule were (846+/-308) microm2 and 3425+/-1374 in atherosclerotic group and (225+/-60) microm2 and 1445+/-606 in xiaoyu tablet 0.32 g/kg group, respectively.

CONCLUSION

Xiaoyu tablet not only inhibited proliferation of SMC through reducing ET-1 in atherosclerotic vessel wall, but also induced apoptosis of SMC by increasing NO in vessel wall.

Multifractality of drop breakup in the air-blast nozzle atomization process

The multifractal nature of drop breakup in the air-blast nozzle atomization process has been studied. We apply the multiplier method to extract the negative and the positive parts of the f(alpha) curve with the data of drop-size distribution measured using dual particle dynamic analyzer. A random multifractal model with the multiplier triangularly distributed is proposed to characterize the breakup of drops. The agreement of the left part of the multifractal spectra between the experimental result and the model is remarkable. The cause of the distinction of the right part of the f(alpha) curve is argued. The fact that negative dimensions arise in the current system means that the spatial distribution of the drops yielded by the high-speed jet fluctuates from sample to sample. In other words, the spatial concentration distribution of the disperse phase in the spray zone fluctuates momentarily, showing intrinsic randomness.

Effect of lipanthyl on mRNA expression of endothelin-1 and nitric-oxide synthase in atherosclerotic vessel wall in rabbits

AIM

To study the mechanism of regression of atherosclerosis (AS) by lipanthyl.

METHODS

Experimental atherosclerotic rabbits created by damaging the abdominal aortic endothelium and feeding with high fat diet for 8 wk were then treated with lipanthyl 15 mg.kg-1.d-1 for 16 wk. Expression of endothelin (ET)-1 mRNA and nitric oxide synthase (NOS) mRNA in atherosclerotic vessel wall was measured by in situ hybridization and reverse transcription polymerase chain reaction (RT-PCR), respectively.

RESULTS

After lipanthyl administration for 16 wk, ET-1 mRNA expression was reduced, and integral optical density (IOD) and area of hybridization granule were observed to be (49,113 +/- 16,868) and (2448 +/- 621) micron 2 in lipanthyl group and (65,188 +/- 10,113) and (3028 +/- 352) micron 2 in atherosclerotic group, respectively. Regarding inducible NOS mRNA expression, IOD and area were decreased by 25.5% and 53.3%, respectively, whereas endothelial NOS mRNA expression was increased.

CONCLUSION

Restoration of the disturbed ET-1 mRNA/NOS mRNA balance by lipanthyl might be one of its mechanisms leading to regression of atherosclerosis.

Seven novel methylation guide small nucleolar RNAs are processed from a common polycistronic transcript by Rat1p and RNase III in yeast

Through a computer search of the genome of the yeast Saccharomyces cerevisiae, the coding sequences of seven different box C/D antisense small nucleolar RNAs (snoRNAs) with the structural hallmarks of guides for rRNA ribose methylation have been detected clustered over a 1.4-kb tract in an inter-open reading frame region of chromosome XIII. The corresponding snoRNAs have been positively identified in yeast cells. Disruption of the nonessential snoRNA gene cluster specifically suppressed the seven cognate rRNA ribose methylations but did not result in any growth delay under the conditions of yeast culture tested. The seven snoRNAs are processed from a common polycistronic transcript synthesized from an independent promoter, similar to some plant snoRNAs but in marked contrast with their vertebrate functional homologues processed from pre-mRNA introns containing a single snoRNA. Processing of the polycistronic precursor requires nucleases also involved in rRNA processing, i.e., Rnt1p and Rat1p. After disruption of the RNT1 gene, the yeast ortholog of bacterial RNase III, production of the seven mature snoRNAs was abolished, while the polycistronic snoRNA precursor accumulated. In cells lacking functional Rat1p, an exonuclease involved in the processing of both pre-rRNA and intron-encoded snoRNAs, several processing intermediates of the polycistronic precursor accumulated. This allowed for the mapping in the precursor of the presumptive Rnt1p endonucleolytic cuts which provide entry sites for subsequent exonucleolytic trimming of the pre-snoRNAs. In line with known properties of double-stranded RNA-specific RNase III, pairs of Rnt1p cuts map next to each other on opposite strands of long double-helical stems in the secondary structure predicted for the polycistronic snoRNA precursor.

Overexpression, purification, and stereochemical studies of the recombinant (S)-adenosyl-L-methionine: delta 24(25)- to delta 24(28)-sterol methyl transferase enzyme from Saccharomyces cerevisiae

The ERG6 gene that encodes (S)-adenosyl-L-methionine: delta 24(25)-to delta 24(28)-sterol methyl transferase (SMT) enzyme from Saccharomyces cerevisiae was introduced into plasmid pET23a(+) and the resulting native protein was overexpressed in BL21 (DE3) host cells under control of a T7 promoter. This enzyme was purified to apparent homogeneity by ammonium sulfate precipitation, anion exchange, and hydrophobic interaction chromatography. N-Terminal sequence analysis of the first 10 amino acids of the purified SMT protein confirmed the identity of the start triplet and expected primary structure. The enzyme exhibited a turnover number of 0.01/s and an isoelectric point of 5.95. A combination of Superose 6 chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the purified SMT enzyme possessed a native molecular weight of 172,000 and was tetrameric. The purified SMT enzyme generated kinetics in which velocity versus substrate curves relative to zymosterol (preferred sterol acceptor molecule) and AdoMet were sigmoidal rather than hyperbolic, indicating enzyme cooperativity among the subunits. Studies on product formation using [27-13C]zymosterol and [2H3-methyl]AdoMet incubated with the pure SMT enzyme confirmed the reaction mechanism of sterol methylation to involve a 1,2-hydride shift of H-24 to C-25 from the Re-face of the original 24,25- double bond. Deduced amino acid sequence comparisons of the SMT polypeptide from S. cerevisiae with related sterol methyl transferase enzymes of plant and fungal origin indicate that there is a significant degree of similarity between these enzymes. Specifically, there is a conserved sequence (in yeast from amino acids ca. 79 to 92 which contains an YEXGWG motif; referred to as Region I) that is not present in other AdoMet-dependent methyl transferase enzymes.