[Evaluation of the determination of hydrogen sulfide in the air of workplace by the detection tube method].

Objective: To evaluate the accuracy and applicability of detection tube method for quantitative detection of hydrogen sulfide in workplace air. Methods: In September 2021, the lower limit of quantification, accuracy, precision, environmental factors, interfering gases and other performance indicators of the method for determining hydrogen sulfide in the air of workplace were verified by the detection tube, and the results were compared with those of GB 11742-89 "Standard method for hygienic examination of hydrogen sulfide in air of residential areas-methylene blue spectrophotometric method" to evaluate the application effect of the detection tube method for quantitative detection of hydrogen sulfide in workplace air. Results: There was no significant difference in the results of 2.83 mg/m(3), 4.25 mg/m(3) and 17.00 mg/m(3) hydrogen sulfide concentration between the two methods (P>0.05) , but there was significant difference in the results of 8.50 mg/m(3) concentration (P<0.05) . The lower limit of quantification of hydrogen sulfide in workplace air was 2.83 mg/m(3), the accuracy was 96.0%-111.0%, and the precision was 0.70%-6.64%. Under the condition of 4 ℃, the measured results decreased by 3.39%-13.10%. When the humidity was 50%-80%, the relative error of the average measured value was -1.67%-4.44%. Interference gases that may exist in the workplace (including carbon dioxide, carbon monoxide, mercaptans, nitrogen oxides, sulfur dioxide, etc.) did not interfere with the results of the test tube. Conclusion: The accuracy and precision of the detection tube method meet the detection requirements. The method is simple, rapid and easy to be popularized, and can be used for the rapid detection of hydrogen sulfide gas concentration in the workplace.

Cloning and characterization of the drought-resistance OsRCI2-5 gene in rice (Oryza sativa L.).

The genomic expression profile of the super-hybrid rice Liangyoupeijiu female parent Pei'ai 64S in different tissues at different developmental stages under low temperature, drought, and high temperature stresses were detected using an Affymetrix GeneChip Rice Genome Array to screen upregulated and downregulated genes. In this study, we screened the drought-resistant gene OsRCI2-5, after which a constitutive OsRCI2-5 construct was created and transferred into Nipponbare. After polyethylene glycol-6000 and drought treatment, we found that the OsRCI2-5 gene improved the drought resistance of Nipponbare. Gene expression profiling showed that the OsRCI2-5 gene was expressed in the rice leaves, stems, and flower organs. Subcellular localization revealed that the gene was located in the membranes, and hence, we can deduce that a membrane signal peptide was responsible for signal transduction.

The mammary gland iodide transporter is expressed during lactation and in breast cancer.

The sodium/iodide symporter mediates active iodide transport in both healthy and cancerous thyroid tissue. By exploiting this activity, radioiodide has been used for decades with considerable success in the detection and treatment of thyroid cancer. Here we show that a specialized form of the sodium/iodide symporter in the mammary gland mediates active iodide transport in healthy lactating (but not in nonlactating) mammary gland and in mammary tumors. In addition to characterizing the hormonal regulation of the mammary gland sodium/iodide symporter, we demonstrate by scintigraphy that mammary adenocarcinomas in transgenic mice bearing Ras or Neu oncogenes actively accumulate iodide by this symporter in vivo. Moreover, more than 80% of the human breast cancer samples we analyzed by immunohistochemistry expressed the symporter, compared with none of the normal (nonlactating) samples from reductive mammoplasties. These results indicate that the mammary gland sodium/iodide symporter may be an essential breast cancer marker and that radioiodide should be studied as a possible option in the diagnosis and treatment of breast cancer.

Influence of affinity and antigen density on antibody localization in a modifiable tumor targeting model.

A persistent question in the field of antibody imaging and therapy is whether increased affinity is advantageous for the targeting of tumors. We have addressed this issue by using a manipulatable model system to investigate the impact of affinity and antigen density on antibody localization. In vitro enzyme-linked immunosorbent assays and bead-binding assays were carried out using BSA conjugated with high and low densities (HD and LD, respectively) of the chemical hapten rho-azophenyl-arsonate as an antigen. Isotype-matched monoclonal antibodies (mAbs) 36-65 and 36-71, with identical epitope specificity but 200-fold differences in affinity, were chosen as targeting agents. The relative in vitro binding of 36-65 and 36-71 was compared with an artificial "tumor" model in vivo using antigen-substituted beads s.c. implanted into SCID mice. Nonsubstituted BSA beads were implanted in the contralateral groin as a nonspecific control. The efficacy of the targeting of [125I]-labeled antibodies was assessed by the imaging of animals on a gamma-scintillation camera using quantitative region-of-interest image analysis over the course of 2 weeks and by postmortem tissue counting. In vitro, both antibodies bound well to the HD antigen, whereas only the high-affinity mAb 36-71 bound effectively to the LD antigen. In vivo, high-affinity mAb 36-71 bound appreciably to both LD and HD beads. In contrast, there was no specific localization of low-affinity mAb 36-65 to LD antigen beads, although the antibody did bind to the beads with the HD antigen. Whereas the high-affinity mAb 36-71 increased its binding to HD beads throughout the 14 days of observation, binding of the high affinity antibody to LD beads and of the low affinity antibody to HD beads plateaued between 10-14 days. These in vitro and in vivo findings demonstrate that the need for a high-affinity antibody is dependent on the density of the target antigen. High-affinity antibodies bind effectively even with a single antigen-Fab interaction, irrespective of the antigen density. In contrast, low-affinity antibodies, because of weak individual antigen-Fab interactions, require the avidity conferred by divalent binding for effective attachment, which can only occur if antigen density is above a certain threshold. An understanding of the differential behavior of high- and low-affinity antibodies and the impact of avidity is useful in predicting the binding of monovalent antibody fragments and engineered antibody constructs and underlies the trend toward development of multivalent immunological moieties. Consideration of the relative density of the antigen on the tumor and the background tissues may enable and even favor targeting with low-affinity antibodies in selected situations.

In vitro and in vivo studies of adenovirus-mediated human norepinephrine transporter gene transduction to hepatocellular carcinoma.

The clinical value of (131)I-MIBG for targeted imaging and targeted radiotherapy is limited to neural crest-derived tumors expressing human norepinephrine transporters (hNET) protein. To extend (131)I-MIBG-targeted therapy to other nonexpressed hNET tumors, this study investigated the hNET expression in vitro and in vivo in HepG2 hepatoma mediated by recombinant adenovirus encoding the hNET gene (Ad-hNET). For this purpose, the HepG2 cells showed a 4.87-fold increase in (125)I-MIBG uptake after infection with Ad-hNET, and the uptake of (125)I-MIBG could be specifically inhibited by maprotiline. Immunohistological analysis, in vivo biological study and (131)I-MIBG scintigraphic imaging also revealed the high expression of hNET protein in hepatoma. This in vitro and in vivo studies demonstrate the feasibility of hNET gene transfer, meditated by adenovirus vector, could extend to tumors other than those derived from the neural crest, which provides a sound foundation for further investigation of hepatocellular carcinoma-targeted radiotherapy mediated by adenovirus transfection with hNET gene.