Changes of electrocardiogram and hemodynamics in response to dipyridamole: In vivo comparative analyses using anesthetized beagle dogs and microminipigs

Microminipigs are expected as a novel animal model for cardiovascular pharmacological experiments. Since inherent vulnerability of coronary circulation of microminipigs has not been characterized, we performed dipyridamole-stress test to both microminipigs and beagle dogs, and compared the results. Dipyridamole in doses of 0.056 and 0.56 mg/kg were intravenously infused over 10 min (n = 4 for each animal). Dipyridamole decreased the systolic/diastolic blood pressures and double product in dogs as well as in microminipigs; but it did not significantly alter the heart rate or the global balance between the myocardial oxygen demand and supply in either animal. While organic coronary arterial stenosis was not detected in either animal, dogs have well-developed epicardial intracoronary networks unlike microminipigs. Like in humans, dipyridamole did not affect the ST segment of microminipigs, whereas it substantially depressed that in dogs. The results indicate the onset of subendocardial ischemia by dipyridamole in dogs may be partly associated with their well-developed native coronary collateral channels. Microminipigs would be more useful to evaluate the drugs which may affect the coronary circulation in the pre-clinical study than dogs.     

Overexpression of p53 protein and histologic grades of dysplasia in colorectal adenomas

PURPOSE: To clarify the relation between tumor-suppressor gene p53 expression and histologic grades of dysplasia in colorectal adenomas, we performed immunohistochemical analysis in a series of 59 colorectal polyps and 40 advanced carcinomas. METHODS: Adenomatous polyps were stained by hematoxylin and eosin and classified into mild, moderate, and severe dysplasia (intramucosal carcinoma), according to the World Health Organization's classification. RESULTS: p53 was positive in 7.1 percent (2/28) of mild, 29.4 percent (5/17) of moderate, and 62.5 percent (5/8) of severe dysplasia. In submucosal and advanced carcinomas, positivity rates were 75 percent (3/4) and 47.5 percent (19/40), respectively. Different staining patterns were found, according to grades of dysplasia. In the adenomas with mild or moderate dysplasia, a few focal crypts showed localized p53-positive staining. Adenomas with severe dysplasia had two different staining types. One was a focal staining type as shown in mild or moderate dysplasia; the other was a diffuse staining type, in which glands with mild or moderate dysplasia, surrounding severe dysplasia area, were also stained. Submucosal and advanced carcinomas showed a strong positive staining in cancer cells only. CONCLUSIONS: Overexpression of p53 protein in adenomas with mild or moderate dysplasia and existence of two types of expression in adenomas with severe dysplasia were observed. These facts suggested the possible existence of different pathways in the adenoma to carcinoma progression.     

Cell proliferation at 122 degrees C and isotopically heavy CH4 production by a hyperthermophilic methanogen under high-pressure cultivation

We have developed a technique for cultivation of chemolithoautotrophs under high hydrostatic pressures that is successfully applicable to various types of deep-sea chemolithoautotrophs, including methanogens. It is based on a glass-syringe-sealing liquid medium and gas mixture used in conjunction with a butyl rubber piston and a metallic needle stuck into butyl rubber. By using this technique, growth, survival, and methane production of a newly isolated, hyperthermophilic methanogen Methanopyrus kandleri strain 116 are characterized under high temperatures and hydrostatic pressures. Elevated hydrostatic pressures extend the temperature maximum for possible cell proliferation from 116°C at 0.4 MPa to 122°C at 20 MPa, providing the potential for growth even at 122°C under an in situ high pressure. In addition, piezophilic growth significantly affected stable carbon isotope fractionation of methanogenesis from CO₂. Under conventional growth conditions, the isotope fractionation of methanogenesis by M. kandleri strain 116 was similar to values (−34‰ to−27‰) previously reported for other hydrogenotrophic methanogens. However, under high hydrostatic pressures, the isotope fractionation effect became much smaller (<−12‰), and the kinetic isotope effect at 122°C and 40 MPa was −9.4‰, which is one of the smallest effects ever reported. This observation will shed light on the sources and production mechanisms of deep-sea methane.     

Immunolocalization of murine type VI 3β-hydroxysteroid dehydrogenase in the adrenal gland,testis, skin,and placenta

The enzyme 3β-hydroxysteroid dehydrogenase/isomerase (3β-HSD) is essential for the biosynthesis of all active steroid hormones, such as those secreted from the adrenal gland, testis, ovary, skin and placenta. The 3β-HSD enzymes exist in multiple isoforms in humans and rodents. To date, six different isoforms have been identified in the mouse, and these isoforms are speculated to play different roles in different tissues. We previously showed that the murine type VI 3β-HSD isoform (Hsd3b6) is expressed specifically in the aldosterone-producing zona glomerulosa cells within the adrenal gland and that its overexpression causes abnormally increased aldosterone synthesis, revealing a crucial (or rate-limiting) role of this enzyme in steroidogenesis. However, potential contributions of this enzyme to the steroid hormone synthesis outside the adrenal glands are poorly understood. This paucity of knowledge is partly because of the lack of isoform-specific antibody that can be used for immunohistochemistry. Here, we report the development and characterization of specific antibody to Hsd3b6 and show the results of immunohistochemistry for the adrenal gland, testis, ovary, skin and placenta. As expected, Hsd3b6 immunoreactivities within the adrenal gland were essentially confined to the zona glomerulosa cells, where aldosterone is produced. By contrast, no immunopositive cells were observed in the zona fasciculata, which is where corticosterone is produced. In the gonads, while the ovaries did not show any detectable immunoreactivity to Hsd3b6, the testes displayed intense immunoreactivities within the interstitial Leydig cells, where testosterone is produced. In the skin, positive immunoreactivities to Hsd3b6 were only seen in the sebaceous glands, suggesting a specific role of this enzyme in sebaceous function. Moreover, in the placenta, Hsd3b6 was specifically found in the giant trophoblast cells surrounding the embryonic cavity, which suggests a role for this enzyme in local progesterone production that is required for proper embryonic implantation and/or maintenance of pregnancy. Taken together, our data revealed that Hsd3b6 is localized in multiple specific tissues and cell types, perhaps thereby involved in biosynthesis of a number of tissue-specific steroid hormones with different physiological roles.     

Persistent epicardial adipose tissue accumulation is associated with coronary plaque vulnerability and future acute coronary syndrome in non-obese subjects with coronary artery disease

Objective. Epicardial adipose tissue (EAT) is recognized as a novel risk factor for coronary artery disease (CAD), and its contribution is thought to be stronger in non-obese patients than in obese patients. However, the prognostic impact of the progression of EAT accumulation after comprehensive management for atherosclerotic risk factors remains unclear. This study aimed to investigate whether an increase of the EAT volume during follow-up predicts future acute coronary syndrome (ACS) events in non-obese CAD patients. Methods. This study consisted of 517 non-obese CAD patients (368 men; age, 66 ± 10 years) who underwent serial multidetector computed tomography (MDCT) examinations to evaluate coronary atherosclerosis progression. The MDCT examination was used to assess the severity of stenosis, plaque characteristics, and EAT volume. All patients received comprehensive management to reduce CAD risk factors after the first MDCT examination. The MDCT examination was repeated at 6–24 months, and patients were followed-up for more than 1 year or until the occurrence of ACS events. Results. Of 517 patients, 159 (31%) patients were classified into increase of EAT volume during follow-up, 91 (18%) into decrease of EAT volume during follow-up, and 267 (51%) patients into constant of EAT volume during follow-up. The prevalence of obstructive plaques and MDCT-derived vulnerable features of coronary plaques were significantly elevated in patients with increase of EAT volume during follow-up. In contrast, no significant changes were observed in the other 2 groups. During the follow-up period of 4.1 ± 1.8 years (median 4.4 years) after the second MDCT examination, ACS occurred in 43 (8.3%) patients. Multivariate Cox regression analysis showed that the presence of low-attenuation plaque (hazard ratio [HR]; 1.78, p = 0.04) and napkin-ring sign (HR; 3.74, p < 0.001) at second MDCT examination, and changes of EAT volume per 10 ml (HR; 1.34, p = 0.004) were associated with future ACS events. Conclusion. Patients with increase of EAT volume during follow-up despite comprehensive management for CAD risks had an increased prevalence of obstructive plaques and plaques with high-risk features, which could be associated with unfavorable ACS outcomes in non-obese CAD patients.     

Infliximab Was Found to Be Effective for Treating Immunosuppressive Drug-resistant Hepatitis due to Durvalumab

A 69-year-old man with stage III lung squamous cell carcinoma developed immune-related hepatitis following treatment with durvalumab, and was given high-dose corticosteroids and immunosuppressive drugs (mycophenolate mofetil, azathioprine, tacrolimus) but without demonstrating any improvement. Two cycles of infliximab (5 mg/kg) were then administered and thereafter the hepatitis improved. At the time of writing (9 months after the initiation of first course of durvalumab), the patient is alive without either any hepatitis symptoms nor any lung cancer progression. Infliximab may be effective for treating non-small cell lung cancer (NSCLC) patients who develop immunosuppressive drug-resistant immune-related hepatitis caused by durvalumab.