Localization of 3′, 5′-cyclic nucleotide phosphodiesterase activity in isolated thyroid cells and intact thyroid tissue

Summary Cytochemical localization of 3,5-cyclic nucleotide phosphodiesterase (cPDEase) has been investigated by light and electron microscopy in dissociated bovine thyroid cells and in intact bovine thyroid tissue. By light microscopy in isolated thyroid cells reaction product deposition associated with cPDEase activity was localized at the level of the plasma membrane. In intact cryostat cut thyroid tissue, the activity was primarily observed in the cytoplasm and to a lesser extent at the level of the plasma membrane. By electron microscopy, cPDEase activity in isolated cells was found on the plasma membrane and was also encountered on the inner surface of membrane bound vacuoles, presumably pinocytic in origin. In intact tissue, cPDEase activity appeared mostly localized on the apical and lateral plasma membranes and was also present on the outer surface of the endoplasmic reticulum (ER).Even though cPDEase and 5-AMPase did share the same plasma membrane localization, the inhibitory response to theophylline and stimulation with Imidazole permitted the dissociation of their respective activities. 5-AMPase failed to respond to either theophylline or Imidazole suggesting absence of cross reactivity between 5-AMP and cyclic AMP. Thyrotropin (TSH) had no effect on cPDEase activity.We conclude that: (1) regardless of the nature of the material used, the cytomembranes of thyroid cells possess cPDEase activity; and that (2) the variability in distribution as well as in staining intensity recorded by light and electron microscopy between isolated thyroid cells and cryostat cut thyroid tissue is probably inherent to the methodology used.This paper was presented, in part, at the 60th Annual Meeting of the International Academy of Pathology, Montreal, Canada, March 1971 and was initiated in the Department of Pathology, Rhode Island Hospital, Providence, R.I., supported from a Grant-in-Aid of the American Cancer Society, Rhode Island Division, Inc. and the Brown-Hazen Fund.     

Carotid body of Camelus dromedarius.

The carotid body of the camel is located between a mass of loose connective tissue at the point of separation of the internal carotid artery from the carotid trunk. A capsule-like connective tissue sheath sends strands in between the parenchyme of this organ and separates lobes and lobules, making it disseminated in type, as in man and in the horse. Two distinct types of cells were found in the parenchyma. Type I cells with specific electton-dense, cored vesicles, and type II cells with protoplasmic extensions. Unlike the previously reported arrangement in the carotid body of some species, the type I cells have direct contact with the basement membrane of glomi and capillaries. Synaptic contacts were seen on both cell types.     

Assay of the possible organization of particle-bound enzymes with squalene synthetase and squalene oxidocyclase systems

Lanosterol was biosynthesized in pig liver homogenate from [4,8,12-(14)C(3)]farnesyl pyrophosphate and [4S-4-(3)H]NADPH through the intermediary formation of squalene labelled asymmetrically with (3)H. The biosynthetic lanosterol, freed from labelled 24,25-dihydrolanosterol, which was also synthesized, was converted into 24,25-dihydrolanosteryl acetate and subjected to chemical degradations to locate the position(s) of the (3)H label in the molecule. The ratio of (3)H at C-11 to that at C-12 was found to be 1.28. Although a certain inequality of labelling was thus indicated, experimental uncertainties did not permit the conclusion that the asymmetrically labelled squalene might have been cyclized preferentially from one end.     

Epstein–Barr virus and thyroid cancer: The role of viral expressed proteins

Background : Thyroid cancer is a common endocrine malignancy whose incidence has increased in recent years. Several internal and external risk factors are involved in the development of this cancer, such as infectious agents. Evidence supporting the role of viral infection as an etiology for the invasiveness of thyroid cancer is increasing. The aim of this study was to determine the presence of the Epstein–Barr virus (EBV) and the association between viral gene products and thyroid tumor development. Methods : Fifty-seven thyroid cancer specimens were collected from the same number of patients as well as 18 samples from healthy controls. The presence of the EBV genome and the genotyping was examined by polymerase chain reaction (PCR). Also, an enzyme-linked immunosorbent assay and real-time PCR were used to measure the expression levels of viral and cellular genes. Results : The EBV DNA was detected in 71.9% of the samples, and it was also found that the presence of the EBV was associated with increasing development of thyroid tumor. Conclusion : Our results demonstrated that EBV infection may play a role in the development of thyroid tumor.     

Calumenin knockdown,by intronic artificial microRNA,to improve expression efficiency of the recombinant human coagulation factor IX

Biotechnology Letters - To improve the expression efficiency of recombinant hFIX, by enhancing its γ-carboxylation, which is inhibited by Calumenin (CALU), we used intronic artificial...     

Eco-friendly nonconjugated polymer dots for chemiluminometric determination of 4-nitrophenol

Polymer dots (PDs) are a new family of quantum dots for which their behavior and potential applications have not yet been completely explored. In this study, nonconjugated PDs were synthesized using a simple pyrolysis method and used for the chemiluminescence (CL) assay of 4-nitrophenol (4-NP). PDs increased the CL signal of the Ce(IV)–Na₂SO₃ reaction 39-fold. Using the CL spectrum, it was concluded that the emission at 434 nm was generated by excited PDs (PDs*), which are produced by energy transfer from SO₂* to PDs. Our experiments showed that 4-NP enhanced the CL signal of the Ce(IV)–Na₂SO₃–PDs reaction. The mechanism of this effect was explored by obtaining CL, ultraviolet–visible, and Fourier transform infrared spectra. Due to the high sensitivity and selectivity of the CL system for 4-NP, a probe was designed to determine 4-NP in the linear range 1.0–500 nmol/L with a detection limit of 0.33 nmol/L. Different spiked real samples were successfully analyzed using this probe.     

Application of a Multi-Criteria Decision-Making Approach for Ranking Environmental Risks Caused by Petrochemical Industries: A Case Study of a Sodium Carbonate Production Unit

The occurrence of accidents in petrochemical industries that cause environmental catastrophes has persuaded experts to use risk-oriented approaches. The approach is to rank the key elements of risk assessment by which the priority of each risk is specified compared to the other ones. The present study was performed to test the applicability of a multi-criteria decision-making approach for prioritizing environmental risks of a petrochemical complex in southwestern Iran. Accordingly, all risky activities of the Sodium Carbonate Production Unit (SCPU) were identified initially. Afterward, the relevant environmental components affected by the risky activities were specified. According to the specification, the most significant risks were shortlisted using experts’ judgment based on three criteria: “impact intensity,” “occurrence probability,” and the “extent of contamination dispersion in the environment.” The shortlisted environmental risks were then prioritized by the Method “Elimination et Choice Translating Reality (Elimination and Choice Expressing Reality)” abbreviated as ELECTRE. Based on the obtained results, “decreased air quality” and “manpower health threatening” are the top-priority risks while “poor quality of groundwater” was identified as the least priority risk. In a general conclusion, a multi-criteria decision-making approach is quite useful for assessing environmental risks of petrochemical industries.     

Biotransformation of methyl tert-butyl ether by human cytochrome P450 2A6

Methyl tert-butyl ether (MTBE) is widely used as gasoline oxygenate and octane number enhancer for more complete combustion in order to reduce the air pollution caused by motor vehicle exhaust. The possible adverse effects of MTBE on human health are of major public concern. However, information on the metabolism of MTBE in human tissues is scarce. The present study demonstrates that human cytochrome P450 2A6 is able to metabolize MTBE to tert-butyl alcohol (TBA), a major circulating metabolite and marker for exposure to MTBE. As CYP2A6 is known to be constitutively expressed in human livers, we infer that it may play a significant role in metabolism of gasoline ethers in liver tissue.