Dynamic matrices with DNA-encoded viscoelasticity for cell and organoid culture

Three-dimensional cell and organoid cultures rely on the mechanical support of viscoelastic matrices. However, commonly used matrix materials lack control over key cell-instructive properties. Here we report on fully synthetic hydrogels based on DNA libraries that self-assemble with ultrahigh-molecular-weight polymers, forming a dynamic DNA-crosslinked matrix (DyNAtrix). DyNAtrix enables computationally predictable and systematic control over its viscoelasticity, thermodynamic and kinetic parameters by changing DNA sequence information. Adjustable heat activation allows homogeneous embedding of mammalian cells. Intriguingly, stress-relaxation times can be tuned over four orders of magnitude, recapitulating mechanical characteristics of living tissues. DyNAtrix is self-healing, printable, exhibits high stability, cyto- and haemocompatibility, and controllable degradation. DyNAtrix-based cultures of human mesenchymal stromal cells, pluripotent stem cells, canine kidney cysts and human trophoblast organoids show high viability, proliferation and morphogenesis. DyNAtrix thus represents a programmable and versatile precision matrix for advanced approaches to biomechanics, biophysics and tissue engineering.

[Analysis of the clinical predictive value of lactate on the prognosis of patients with acute-on-chronic liver failure combined with infection]

Objective: To explore the predictive value of lactic acid for the adverse prognostic outcomes in patients with acute-on-chronic liver failure combined with infection. Methods: A retrospective analysis was conducted on the clinical data of 208 cases of ACLF combined with infection who were hospitalized from January 2014 to March 2016. Patients were divided into a survival group (n = 83) and a mortality group (n = 125) according to the results of a 90-day follow-up. The clinical data were statistically analyzed between the two groups. Multivariate logistic regression with two categorical variables was used to analyze the independent risk factors for 90-day disease mortality and establish a new prediction model. The receiver operating characteristic curve (ROC curve) was used to evaluate the predictive value of lactic acid, the MELD score, the MELD-Na score, lactic acid combined with the MELD score, lactic acid combined with the MELD-Na score, and the new model. Results: The 90-day mortality rate of 208 cases of ACLF combined with infection was 60.1%. There were statistically significant differences in white blood cell count, neutrophil count, total bilirubin (TBil), serum creatinine (Cr), blood urea nitrogen (BUN), blood ammonia, the international normalized ratio (INR), lactic acid (LAC), procalcitonin, the MELD score, the MELD-Na score, hepatic encephalopathy (HE), acute kidney injury (AKI), and bleeding between the two groups. Multivariate logistic regression analysis showed that TBil, INR, LAC, HE, and bleeding were independent risk factors for 90-day mortality in patients with ACLF combined with infection. After the establishment of MELD-LAC, MELD-Na-LAC, and a new prediction model, the ROC curve revealed that the AUC (95% confidence interval) of MELD-LAC and MELD-Na LAC were 0.819 (0.759 ~ 0.870) and 0.838 (0.780 ~ 0.886), respectively, and was superior than the MELD score [0.766 (0.702 ~ 0.823)] and MELD-Na score [0.788 (0.726 ~ 0.843)], with P < 0.05, while the new model had an AUC of 0.924, the sensitivity of 83.9%, specificity of 89.9%, and accuracy of 87.8%, which was higher than LAC, MELD score, MELD-Na score, MELD-LAC, and MELD-Na-LAC (P < 0.01). Conclusion: Lactic acid is an independent risk factor for mortality in patients with ACLF combined with infection, and it improves the clinical predictive value of MELD and MELD-Na for the prognosis of mortality.

[Relationship between etiology and morphological classification of benign central airway stenosis and its prognosis]

Objectives: To analyze the relationship between etiology and morphological classification of benign central airway stenosis and its prognosis. Methods: We performed a retrospective study of the medical records of 453 patients initially diagnosed with benign airway stenosis at Department of Respiratory Diseases in Beijing Tiantan Hospital affiliated to Capital Medical University from January 2003 to October 2019. Of 453 patients, 260 were male. The age of the study population was 12-86(44.0±24.5) years. Results: Among the 453 patients diagnosed with benign central airway stenosis, 161 case (35.5%, including 113 post-tracheostomy tracheal stenosis and 48 post-intubation tracheal stenosis) were iatrogenic; 88 cases were from benign tumors (19.4%), 77 cases from tracheal or bronchial tuberculosis (17.0%), 71 case from tracheal foreign bodies (15.7%). Disease causes varied among different gender or age groups. The main type of stenosis was structural stenosis, of which 241 cases (53.2%) were intra-luminal and 183 cases (40.4%) were scar contracture type. The site of stenosis showed a certain relationship with the causes of stenosis. The stenosis degree was mainly from grade 2 to grade 4 (76.4%), and the length was mainly within 3 cm (84.8%). Single factor analysis on the relationship between disease cause, morphological classification and prognosis of benign central airway stenosis showed statistically better prognosis in groups that were caused by benign tumor, intraductal stenosis or stenosis that were 3-4 in degree and 1-2 degree in length. Conclusion: The common causes of central airway stenosis included iatrogenic stenosis, benign tumor, tracheal or bronchial tuberculosis and tracheal foreign bodies. Benign airway stenosis with different disease causes and morphological classification had different prognosis after bronchoscopic interventional treatment. Clinicians should know the disease causes, morphological characterization and risk factors for benign airway stenosis for earlier diagnosis, treatment or prevention.

[Clinical features and imaging analysis of primary bone lymphoma of the jaw]

Objective: To investigate the clinical characteristics and imaging manifestations of primary bone lymphoma (PBL) located in the jaw. Methods: Clinical data of 14 PBL patients admitted to The First Affiliated Hospital of Zhengzhou University from January 2014 to April 2019 were retrospectively analyzed, which including age, gender, location, chief complaint, laboratory test, imaging manifestations and so on. Results: Among the 14 PBL patients, 10 were male and 4 were female. Age range from 4 to 79 years, median age was 56 years old. There were 6 cases involved maxillary, 7 cases involved mandible and 1 case involved mandible and maxillary simultaneously. Twelve patients were admitted with local mass as the chief complaint, 3 had a history of toothache, 4 had loosen tooth and 2 had numbness of lips and cheeks. Two cases of oral mass with mucosal surface ulcer or abscess formation. One case complained of fever, night sweats and other systemic symptoms. The imaging findings showed 8 cases of osteolytic lesions, 1 case of sclerosis, 4 cases of mixed lesions and 1 case of cystic lesions. One case had periosteum reaction. In 12 cases, there was an obvious mass, which was characterized by the large soft-tissue mass and marrow changes were associated with surprisingly little cortical destruction. Conclusions: PBL is more common in middle aged male. The upper and lower jaw bones can be involved. Clinical and imaging manifestations lack characteristics, and common dental or periodontal symptoms such as toothache, tooth loosening, and paresthesia may occur. However, the imaging characteristics of large soft tissue masses with small degree of bone destruction can be used as an important basis for the differential diagnosis of osteomyelitis, squamous cell carcinoma, osteosarcoma and other diseases.

Triple-Junction Optoelectronic Sensor with Nanophotonic Layer Integration for Single-Molecule Level Decoding

Interest in developing a rapid and robust DNA sequencing platform has surged over the past decade. Various next-/third-generation sequencing mechanisms have been employed to replace the traditional Sanger sequencing method. In sequencing by synthesis, a signal is monitored by a scanning charge-coupled device (CCD) to identify thousands to millions of incorporated dNTPs with distinctive fluorophores on a chip. Because one reaction site usually occupies dozens of pixels on a CCD detector, a bottleneck related to the bandwidth of CCD imaging limits the throughputs of the sequencing performance and causes trade-offs among speed, accuracy, read length, and the numbers of reaction sites in parallel. Thus, current research aims to align one reaction site to a few pixels by directly stacking nanophotonic layers onto a CMOS detector to minimize the size of the sequencing platforms and accelerate the processing procedures. This article reports a custom integrated optoelectronic device based on a triple-junction photodiode (TPD) CMOS sensor in conjunction with NPL integration for real-time illumination and detection of fluorescent molecules.

[A study of bacterial distribution and drug resistance in skin and soft tissue infection]

Objective: To investigate pathogenic bacteria and drug resistance in the patients with skin and soft tissue infection in order to provide the scientific evidences for clinical reasonable use of antibiotics. Methods: A retrospective analysis was performed on patients with skin and soft tissue infections in Department of Dermatology, Peking University Third Hospital from January 2012 to December 2017. Pus, secretions, skin lesions, urine, throat swabs, and alveolar lavage fluid were collected for bacterial culture, bacterial species were identified by VITEK2 Compact system and BD-Bruker MALDI Biotyper system. Drug resistance was detected by K-B agar diffusion method recommended by CLSI. Results: A total of 392 strains of bacteria were isolated from 327 patients distributed in 21 genus and 56 species, of which 225 were gram-positive cocci (57.40%), 114 were gram-negative rods (29.08%), 46 were gram-positive rods (11.73%), and 7 were gram-negative cocci (1.79%). The top 3 bacteria were Staphylococcus aureus 91(23.21%), Staphylococcus epidermidis 42 (10.71%), and Pseudomonas aeruginosa 24 (6.12%). Staphylococcus had a high rate of resistance to penicillin and erythromycin (>50%). Gram-negative rods were resistant to ampicillin (86.1%), and also had certain resistance to most second-generation and some third-generation cephalosporin (about 50%). There was no significant change in the drug resistance rate of MRSA compared to MSSA. Only the resistance rate to tetracycline was statistically different (P<0.05). Conclusion: The emergence of drug-resistant strains is an important factor leading to refractory infections. There are a wide range of pathogenic bacteria species among the skin and soft tissue infection patients, and antimicrobial drugs should be chosen wisely according to drug sensitivity.

[Mechanism research progress of miRNA in laryngeal carcinoma]

MiRNA(miR) is a non-coding small RNA of 18 to 24 nucleotides in length.By pairing with 3'UTR of its target mRNA molecule, miRNA regulateS the target mRNA molecule in the translation level or directly lead to its degradation. Each miRNA may target several to several hundred mRNAs, of which 30% of the mRNA is regulated by miRNAs. Some studies have shown that miRNA expression disorders play an important role in the development and progression of various tumors and may be the ideal target for tumor therapy. It has been shown that abnormal expression of RNA (miRNA) plays an important role in the occurrence and development of laryngeal cancer. Wang Ping found 47 kinds of miRNA expression abnormalities in laryngeal cancer tissue with microarray chip detection, that of which high expression were 23 kinds and low expression were 24 kinds. MiRNAs that are abnormally expressed in laryngeal squamous cell carcinoma are expected to be a new marker for early diagnosis of laryngeal cancer. In this review, we summarized the progress in recent three years on the association of miRNA and the biological behaviors of laryngeal cancer.

[Clinical characteristics of allergic rhinitis allergen spectrum in Gannan area]

Objective:To study the clinical features of common allergens in patients with allergic rhinitis in Gannan area and provide reference for the prevention，diagnosis and treatment of allergic rhinitis with regional character.MethodThe clinical data of 363 patients who were newly diagnosed with allergic rhinitis and given allergen skin prick test（skin prick test，SPT）at our department from August 2012 to May 2016 were analyzed retrospectively.SPSS 180 was used to ananlyze the data.Result:Two hundred and fifty-two cases of allergen skin prick test were positive.The positive rates of allergens were 86.90% of house dust mites，86.11% of dust mites，51.19% of cockroach，14.29% of hair fungus，4.76% of crab meat and 3.17% of shrimp.The positive rate of various allergens in the children group was 93.24% for dust mites，91.89% for house dust mites，44.59% for cockroach，8.11% for crab meat，6.76% for shrimp，and 1.35% for hair fungus.The difference in positive rate of allergens among different age groups was statistically significant（P<0.01），among which the highest was 2 to 14 years old，which was 90.24%；the lowest was ＞44 to 74 years old，which was 31.70%.The difference in positive rates of allergens among different occupations was statistically significant（P<0.01），among which the highest was 86.45% for students，and the lowest was 45.24% for those without employment.There was no significant difference in the positive rate of allergens between different seasons.ConclusionThe most common allergens in Gangnan area are house dust mites，dust mites cockroache and scrab meat.Patients with allergic rhinitis are more common with multiple allergens.Age and occupation are also factors affecting the positive rate of allergens.

Effects of nonsteroidal anti-inflammatory drugs on the renal excretion of indoxyl sulfate, a nephro-cardiovascular toxin, in rats

Chronic kidney disease (CKD) is a health problem worldwide. Indoxyl sulfate (IS) is a nephro-cardiovascular toxin accumulated in CKD patients and cannot be removed through hemodialysis. The renal excretion of IS was mediated by organic anion transporters (OATs) OAT 1 and OAT 3. Because a number of nonsteroidal anti-inflammatory drugs (NSAIDs) have been reported to inhibit OATs, we hypothesize that NSAIDs might inhibit the renal excretion of IS. Rats were intravenously injected IS with and without diclofenac, ketoprofen or salicylic acid, individually. Blood samples were collected at predetermined time points and the concentrations of IS were determined by HPLC method. The results showed that diclofenac and ketoprofen at 10.0mg/kg significantly decreased the systemic clearance of IS by 71% and 82%, and increased the MRT of IS by 106% and 105%, respectively, whereas salicylic acid did not exhibit significant effects. Cell studies indicated that diclofenac and ketoprofen inhibited the uptake of IS mediated by OAT 1 and OAT 3. In conclusion, diclofenac and ketoprofen inhibited the excretion of IS through inhibition on OAT 1 and OAT 3.

Development and characterization of microsatellite loci in Excentrodendron hsienmu (Chun & How) H.T. Chang& R.H. Miau

Microsatellite markers were isolated using dual-suppression-PCR for the endangered species Excentrodendron hsienmu (Tiliaceae) to evaluate the genetic diversity and population structure of this species. A total of 11 polymorphic microsatellite loci were characterized in E. hsienmu. The number of alleles per locus ranged from 2 to 9, with an average of 5.27. The expected heterozygosity value ranged from 0.053 to 0.780, with an average of 0.568 and the observed heterozygosity value ranged from 0 to 0.595, with an average of 0.268. The polymorphic information content value ranged from 0.051 to 0.740, with an average of 0.521. These newly designed markers will be of great potential significance and profound influence in future research related to the genetic diversity, population structure, and patterns of gene flow of this species, which will contribute to the implementation of conservation and management strategies for this species.

Characterization and identification of streptococci from golden pompano in China

Streptococcal infections cause significant mortality and high economic losses in the fish farm industry worldwide, including in the culture of golden pompano Trachinotus ovatus L., a species gaining popularity in China. A total of 9 streptococcal strains were isolated from cage-cultured diseased golden pompano in Beihai, Zhanjing, and Shenzhen, China, between 2012 and 2014. Conventional and rapid identification systems were used to determine that the isolates were Streptococcus agalactiae, S. iniae, and S. dysgalactiae subsp. dysgalactiae. All isolates were gram-positive cocci cells in pairs or short-chain, non-motile, catalase negative, α or β hemolytic cocci. The results of multiplex PCR assays and 16S rRNA BLAST analysis also showed that the β hemolytic strains were S. agalactiae and S. iniae and the α hemolytic strain was S. dysgalactiae subsp. dysgalactiae, respectively. Pathogenicity assays revealed that S. agalactiae (lethal dose [LD50]: 6.38 × 10(4) CFU ml(-1)) was more virulent for golden pompano than S. iniae (LD50: 1.47 × 10(7) CFU ml(-1)) and S. dysgalactiae subsp. dysgalactiae (LD50: 2.57 × 10(6) CFU ml(-1)) when they were challenged by intraperiotoneal (i.p.) injection. The results of antibiotic susceptibility showed that all strains were extremely susceptible to cefradine, erythromycin, and cefotaxime but resistant to gentamicin, penicillin G, novobiocin, neomycin, ciprofloxacin, roxithromycin, furazolidone, enrofloxacin, norfloxacin, kanamycin, ampicillin, tetracycline, and vancomycin This is the first report of a phenomenon of golden pompano coinfection with S. agalactiae and S. iniae, which will contribute to the diagnosis and prevention of streptococcicosis.

Green tea inhibited the elimination of nephro-cardiovascular toxins and deteriorated the renal function in rats with renal failure

Chronic kidney disease (CKD) is a major health problem worldwide. Indoxyl sulfate (IS) and p-cresyl sulfate (PCS) are highly protein-bound nephro-cardiovascular toxins, which are not efficiently removed through hemodialysis. The renal excretions of IS and PCS were mediated by organic anion transporters (OATs) such as OAT1 and OAT3. Green tea (GT) is a popular beverage containing plenty of catechins. Previous pharmacokinetic studies of teas have shown that the major molecules present in the bloodstream are the glucuronides/sulfates of tea catechins, which are putative substrates of OATs. Here we demonstrated that GT ingestion significantly elevated the systemic exposures of endogenous IS and PCS in rats with chronic renal failure (CRF). More importantly, GT also significantly increased the levels of serum creatinine (Cr) and blood urea nitrogen (BUN) in CRF rats. Mechanism studies indicated that the serum metabolites of GT (GTM) inhibited the uptake transporting functions of OAT1 and OAT3. In conclusion, GT inhibited the elimination of nephro-cardiovascular toxins such as IS and PCS, and deteriorated the renal function in CRF rats.

Wnt signaling and tbx16 form a bistable switch to commit bipotential progenitors to mesoderm

Anterior to posterior growth of the vertebrate body is fueled by a posteriorly located population of bipotential neuro-mesodermal progenitor cells. These progenitors have a limited rate of proliferation and their maintenance is crucial for completion of the anterior-posterior axis. How they leave the progenitor state and commit to differentiation is largely unknown, in part because widespread modulation of factors essential for this process causes organism-wide effects. Using a novel assay, we show that zebrafish Tbx16 (Spadetail) is capable of advancing mesodermal differentiation cell-autonomously. Tbx16 locks cells into the mesodermal state by not only activating downstream mesodermal genes, but also by repressing bipotential progenitor genes, in part through a direct repression of sox2. We demonstrate that tbx16 is activated as cells move from an intermediate Wnt environment to a high Wnt environment, and show that Wnt signaling activates the tbx16 promoter. Importantly, high-level Wnt signaling is able to accelerate mesodermal differentiation cell-autonomously, just as we observe with Tbx16. Finally, because our assay for mesodermal commitment is quantitative we are able to show that the acceleration of mesodermal differentiation is surprisingly incomplete, implicating a potential separation of cell movement and differentiation during this process. Together, our data suggest a model in which high levels of Wnt signaling induce a transition to mesoderm by directly activating tbx16, which in turn acts to irreversibly flip a bistable switch, leading to maintenance of the mesodermal fate and repression of the bipotential progenitor state, even as cells leave the initial high-Wnt environment.

A facile approach to prepare silicon-based Pt-Ag tubular dendritic nano-forests (tDNFs) for solar-light-enhanced methanol oxidation reaction

In this paper, a facile two-step Galvanic replacement reaction (GRR) is proposed to prepare Pt-Ag tubular dendritic nano-forests (tDNFs) in ambient condition for enhancing methanol oxidation reaction (MOR) under solar illumination. In the first GRR, a homogeneous layer of silver dendritic nano-forests (DNFs) with 10 μm in thickness was grown on Si wafer in 5 min in silver nitride (AgNO3) and buffer oxide etchant (BOE) solution. In the second GRR, we utilized chloroplatinic acid (H2PtCl6) as the precursor for platinum (Pt) deposition to further transform the prepared Ag DNFs into Pt-Ag tDNFs. The catalytic performance and solar response of the Pt-Ag tDNFs toward methanol electro-oxidation are also studied by cyclic voltammetry (CV) and chronoamperometry (CA). The methanol oxidation current was boosted by 6.4% under solar illumination on the Pt-Ag tDNFs due to the induced localized surface plasmon resonance (LSPR) on the dendritic structure. Current results provide a cost-effective and facile approach to prepare solar-driven metallic electrodes potentially applicable to photo-electro-chemical fuel cells.

Oral intake of curcumin markedly activated CYP 3A4: in vivo and ex-vivo studies

Curcumin, a specific secondary metabolite of Curcuma species, has potentials for a variety of beneficial health effects. It is nowadays used as a dietary supplement. Everolimus (EVL) is an immunosuppressant indicated for allograft rejection and cancer therapy, but with narrow therapeutic window. EVL is a substrate of P-glycoprotein (P-gp) and cytochrome P450 3A4 (CYP3A4). This study investigated the effect of coadministration of curcumin on the pharmacokinetics of EVL in rats and the underlying mechanisms. EVL (0.5 mg/kg) was orally administered without and with 50 and 100 mg/kg of curcumin, respectively, in rats. Blood samples were collected at specific time points and EVL concentrations in blood were determined by QMS® immunoassay. The underlying mechanisms were evaluated using cell model and recombinant CYP 3A4 isozyme. The results indicated that 50 and 100 mg/kg of curcumin significantly decreased the AUC_0-540 of EVL by 70.6% and 71.5%, respectively, and both dosages reduced the C_max of EVL by 76.7%. Mechanism studies revealed that CYP3A4 was markedly activated by curcumin metabolites, which apparently overrode the inhibition effects of curcumin on P-gp. In conclusion, oral intake of curcumin significantly decreased the bioavailability of EVL, a probe substrate of P-gp/CYP 3A4, mainly through marked activation on CYP 3A4.

Serum concentrations of anthraquinones after intake of Folium Sennae and potential modulation on P-glycoprotein

Folium Sennae (leaves of Cassia angustifolia or senna) is a laxative and a component in diets for weight control. It contains a variety of anthranoids such as sennosides, aloe-emodin, and rhein. In order to measure the serum concentrations of senna anthranoids, Sprague-Dawley rats were orally administered with single dose and multiple doses of Folium Sennae. The concentrations of anthranoids in serum were determined by HPLC method before and after hydrolysis with sulfatase and β-glucuronidase. The results showed that in the serum, aloe-emodin glucuronides and rhein glucuronides were the major metabolites. Traces of rhein free form were present transiently during the early phase, whereas the free form of aloe-emodin was not detected. We also evaluated the modulation effect of Folium Sennae on P-glycoprotein by using the LS 180 cell model which showed that it significantly inhibited P-glycoprotein by 16-46 %. In conclusion, senna anthranoids were rapidly and extensively metabolized to rhein glucuronides and aloe-emodin glucuronides in rats. Folium Sennae ingestion inhibited the efflux function of P-glycoprotein in the intestine.

Development and characterization of microsatellite loci in a threatened marine fish, Cheilinus undulatus (humphead wrasse)

Cheilinus undulatus (humphead wrasse) is a marine fish distributed widely throughout the tropical Indo-Pacific. It has been listed as vulnerable in the IUCN Red Data Book and in CITES Appendix II four times. Fifteen microsatellite loci were isolated and characterized for this species. The number of alleles ranged from 3 to 15 per locus, and the observed and expected heterozygosity ranged between 0.0323-0.7742 and 0.2597-0.8773, respectively. The polymorphism information content ranged from 0.2353-0.8520. Four microsatellite loci deviated significantly from Hardy-Weinberg expectations. No significant linkage disequilibrium was found among any of the loci. These microsatellite loci will be useful for future investigations of genetic variation in the wrasse population.

Isolation and characterization of 16 microsatellite loci in marble goby (Oxyeleotris marmoratus)

A microsatellite-enriched genomic library for marble goby (Oxyeleotris marmoratus), a freshwater fish of considerable economic value, was obtained. A total of 16 microsatellite markers were successfully isolated and characterized in a population from the Mekong River in Vietnam. These markers had 2-20 alleles with expected heterozygosity ranging from 0.0370 to 0.8927. Linkage equilibrium was observed in most loci, and only 1 locus revealed a significant deviation from Hardy-Weinberg equilibrium. These microsatellite markers will be useful for genetic diversity and molecular marker-assisted selection studies of wild and farmed O. marmoratus.

Electroluminescence enhancement of SiGe/Si multiple quantum wells through nanowall structures

The enhancement of light extraction from Si(0.5)Ge(0.5)/Si multiple quantum wells (MQWs) with nanowall structures fabricated by electron cyclotron resonance (ECR) plasma etching is presented. It is shown that the ECR plasma treatment does not damage the crystalline quality. At a driving current of 5.5 × 10(6) A m(-2), the light output intensity of the MQWs with nanowall structures shows an enhancement of about 50% compared with that of the original MQWs. In addition to the enhanced light extraction, the improved optoelectronic properties are also attributed to the strain relaxation in nanowall structures.

Analysis of the entire genomes of thirteen TT virus variants classifiable into the fourth and fifth genetic groups, isolated from viremic infants

TT virus (TTV) DNA in serum samples obtained from 24 TTV-infected infants was amplified by polymerase chain reaction (PCR) with inverse primers derived from the untranslated region. The amplified PCR products were molecularly cloned; six clones each were analyzed. Seventy-six (53%) of the 144 TTV clones were classified into group 4 (YONBAN isolates), and 22 (15%) into a novel genetic group (group 5). The TTV clones in group 4 were classified into 9 types, and those in group 5 into 4 types. The entire nucleotide sequence of one representative clone each from the 13 types were determined; they comprised 3570-3770 nucleotides, and had poor homology to TTVs of groups 1-3 (TA278, PMV and SANBAN isolates). A phylogenetic tree based on the entire nucleotide sequence of open reading frame 1 confirmed the presence of five distinct clusters separated by a bootstrap value of 100%. Analysis of 13 TTV variants demonstrated preservation of the genomic organization and transcription profile in all TTV groups. TTV group 4 was detected in 54% or 72% of 7-to-12-month-old infants in Japan and China, respectively, which is comparable with that among adults in the respective country, indicating early and frequent acquisition of this TTV group in infancy.

Fish allergy in atopic children

The prevalence of fish allergy among 11 atopic children with elevated levels of specific immunoglobulin (Ig) E for cod was determined. None of the children had a history of fish allergy. All of the children had asthma and allergic rhinitis and 5 of them had also atopic dermatitis. The children underwent allergy skin tests (codfish, tuna, catfish, salmon, flounder, and bass), specific IgE tests (salmon, trout, tuna, eel, and mackerel), and food challenge tests. Skin tests in cod-specific IgE-positive children were positive for codfish in 4 children, tuna in 2, catfish in 2, salmon in 6, flounder in one, and bass in 2. Three children had elevated specific IgE for salmon, 5 for trout, 8 for tuna, 4 for eel, and 4 for mackerel. Oral fish challenge with 10 g of fish did not result in positive reaction in any of the children. In conclusion, a positive food challenge test provided the only definitive confirmation of fish allergy, whereas positive allergy skin tests or positive specific IgE tests were less reliable. Skin tests and in vitro specific IgE assays were not correlated with clinical symptoms of fish allergy, and the results of these 2 tests did not correlate with each other in this study.

Essential role of Drosophila Hdac1 in homeotic gene silencing

Deacetylation of the N-terminal tails of core histones plays a crucial role in gene silencing. Rpd3 and Hda1 represent two major types of genes encoding trichostatin A-sensitive histone deacetylases. Although they have been widely found, their cellular and developmental roles remain to be elucidated in metazoa. We show that Drosophila Hdac1, an Rpd3-type gene, interacts cooperatively with Polycomb group repressors in silencing the homeotic genes that are essential for axial patterning of body segments. The biochemical copurification and cytological colocalization of HDAC1 and Polycomb group repressors strongly suggest that HDAC1 is a component of the silencing complex for chromatin modification on specific regulatory regions of homeotic genes.

Response of pollen germination and tube growth to cadmium with special reference to low concentration exposure

Cadmium is one of the most important heavy metal pollutants highly hazardous to plants. Pollen is considered to be more sensitive to pollutants than are vegetative parts of the plants. Five herb species were tested for responses in pollen germination and tube growth to Cd exposure in vitro. Pollen germination of all the species was inhibited at Cd concentrations of 2.51 microg/mL and higher, and tube growth was inhibited at concentrations of 1.58 microg/ml and higher. Cadmium, at low concentrations, stimulated pollen tube growth. The pollen response to Cd stress exhibited interspecies differences. Vicia angustifolia and V. tetrasperma were sensitive to Cd, and were inhibited in either pollen germination or tube growth by Cd at 0.01 microg/mL. Plantago depressa was less sensitive; pollen germination and tube growth were not inhibited until the Cd concentration reached 2.51 and 1.58 microg/mL, respectively, and its tube growth displayed two stimulatory peaks; the one that appeared at 1.00 microg/mL showed the highest tube length in all species tested. These results suggest that Cd, even at low concentrations, may adversely affect plant reproduction by inhibiting pollen germination and tube growth.

Mutations in the HC-Pro gene of zucchini yellow mosaic potyvirus: effects on aphid transmission and binding to purified virions

Transmission of zucchini yellow mosaic virus (ZYMV) by aphids was examined by introducing mutations within the highly conserved proline-threonine-lysine (PTK) motif of the helper component proteinase (HC-Pro) using a cDNA full-length clone. Replacement of proline by alanine (ATK) in the PTK motif abolished transmission almost completely both from plants and from membranes. Substitution of the basic lysine by glutamic acid (PTE) did not reduce the rate of transmission compared with the wild-type. Replacement of threonine by valine (PVK) or serine (PSK) resulted in a rate of transmission that was lower than that of the wild-type. The rate was lower for PSK than for PVK. Western blot comparison did not permit attribution of HC-Pro functionality in transmission to its level in the host. The HC-Pro of strains that effected transmission (with the wild-type PTK motif, and with the mutated PTE and PVK motifs) could also bind in vitro to virions of ZYMV. HC-Pro with a PSK motif, which was less effective in assisting transmission, could bind only weakly to virions, while HC-Pro of the almost non-transmissible strains (with PAK and ATK motifs) did not bind at all. Interestingly, positive binding was recorded for transmission-defective ZYMV-Ct, which has a PTK motif but has glutamic acid instead of lysine in the lysine-leucine-serine-cysteine (KLSC) motif. These findings support the 'bridge hypothesis', and confirm the binding of the HC-Pro to the virion. The possible role of the PTK and KLSC motifs in binding to the virus and to the mouthparts of the aphid is discussed.

Protein synthesis in rat intestine in vitro: the acute effect of ethanol

We studied the rate of 3H-leucine incorporation and the acute effect of ethanol on rat jejunum employing a newly-developed method originally for determining rapid solute uptake in vitro. 3H-leucine incorporation was linear up to 12 min and significantly inhibited by 10 microM of cycloheximide, a specific inhibitor for protein synthesis. The inhibition was 86% at 100 microM indicating that the rate of 3H-leucine incorporation was a good index for protein synthetic activity in the intestinal cells. Incorporation was not changed significantly by 8% dilution (with water) but was inhibited by 8% ethanol to less than 1/4 of the control level. Lower concentrations of ethanol had no consistent effects. The action of ethanol was rapid, independent of the precursor level, and was not readily reversible. Although the nature of ethanol's action was not clear, sucrose, in a dose-dependent manner, also significantly inhibited incorporation rapidly, indicated that the action of media hyperosmolality could not be eliminated as part of the cause of inhibition induced by ethanol.