Extremely early onset of ranitidine action on human histamine H2 receptors expressed in HEK293 cells

BACKGROUND/AIMS: Histamine H2 receptor antagonists are considered to exert their effects on gastric acid secretion more rapidly than proton pump antagonists. However, there are no reports concerning the direct interaction of a histamine H2 receptor antagonist with the human H2 receptor in terms of onset of action. This study aims to characterize how rapidly famotidine and ranitidine, the most widely used histamine H2 receptor antagonists, interact with the human histamine H2 receptor. METHODS: HEK293 cell lines, stably expressing human histamine H2 receptors, were obtained. The dose- and time-dependent effects of famotidine and ranitidine on [3H]-tiotidine binding and histamine-stimulated cAMP production were analyzed. RESULTS: Ranitidine inhibited both [3H]-tiotidine binding and histamine-stimulated cAMP production more promptly than did famotidine. Inhibition of histamine-stimulated cAMP production by Cmax doses of famotidine (20 mg p.o.) and ranitidine (150 mg p.o.) peaked by 15 and 2 min, respectively. [3H]-tiotidine binding was not saturated by 60 min at the famotidine Cmax, while the ranitidine Cmax had produced saturation by 15 min. CONCLUSION: Ranitidine inhibits the human histamine H2 receptor very rapidly.     

Analysis of K-<Emphasis Type="Italic">ras</Emphasis> Codon 12 Mutation in Flat and Nodular Variants of Serrated Adenoma in the Colon

PURPOSE: The developmental process of serrated adenomas is obscure, and the importance of genetic alterations has not been elucidated clearly. The possibility that the developmental process and genetic alterations of serrated adenomas could differ from those of ordinary tubular adenomas was explored in this work. METHODS: Serrated adenomas were obtained by endoscopic resection (n = 57) and divided into two groups: flat (n = 10) and nodular (n = 47). Mutation of the K-ras gene was analyzed by enriched polymerase chain reaction–enzyme-linked mini-sequence assay, which can detect not only the presence of a mutation but also the mutation type of K-ras codon 12 with high sensitivity. Methylation-specific polymerase chain reaction was performed with specific primers for the DNA repair gene O6-methylguanine-DNA methyltransferase. RESULTS: Serrated adenomas located in the rectum were more likely to have a K-ras mutation (9/12, 75 percent), whereas serrated adenomas of the flat type were less likely to have one (1/10, 10 percent). Furthermore, nodular serrated adenomas that occurred in the rectum possessed a high frequency of K-ras gene codon 12 point mutation (8/10, 80 percent) despite an overall frequency of 46.8 percent (22/47). A mutation of the K-ras codon 12 gene was detected in 23 (40.4 percent) of 57 serrated adenomas. Three types of point mutations of codon 12 were detected, with the mutation of GAT being observed most frequently. CONCLUSIONS: This study shows that development of nodular serrated adenomas may depend on the mutation of the K-ras codon 12 gene, whereas development of flat serrated adenomas may not. Additionally, serrated adenomas that occur in the rectum are closely related to the mutation of the K-ras codon 12 gene. K-ras mutations in serrated adenomas may be unaffected by the epigenetic silencing of O6-methylguanine-DNA methyltransferase by promoter hypermethylation.     

Role of case presentation for teaching and learning activities

In most clinical teaching settings, case presentation is the most frequently used teaching and learning activity. From an educational viewpoint, the two important roles of case presentations are the presenter's reflective opportunity and the clinician educator's clues to diagnose the presenter. When a presenter prepares for a case presentation, he/she has to organize all the information collected from a patient. The presenter sometimes does not recall what to ask or to examine with relation to pertinent differential diagnoses while seeing a patient, and afterward he/she might note that more information should have been collected. He/she is able to note the processes by reflection-on-action and improve the processes the next time. Such a reflective process is the most important role of case conference for a presenter. When a clinician has a consultation with a patient, early problem representation determines the quality of differential diagnoses. Clinicians make a "big picture" while listening to the patient (sometimes only a glance is enough to diagnose a patient) as problem representation to narrow down clinical areas to ask questions. If the early problem representation is far from the optimal direction, the possibility of misdiagnosis will be higher. To correct the cognitive processes that lead to misdiagnosis, disclosure of uncertainty will be the key. If the teaching environment among residents or young clinicians is too competitive, some might feel reluctant to disclose incorrect reasoning processes to their peers. Or, if a clinician educator is too authoritative, students may hide key information from the educator. The educator should construct the best environment for students to be able to disclose such uncertainty. The main role of clinician educators is to facilitate and evaluate case presentations and to suggest points for improvement. Neher et al's "five microskills" are a typical example of these processes, after a short presentation of an outpatient case. Yet, for an inpatient or for formal discussion, a longer version presentation is used. To improve the clinical reasoning processes of the presenter, the short presentation has several advantages: (1) shortening the presentation requires abstraction of information, possibly leading to better problem representation; (2) it is time-efficient; and (3) it stimulates more informal interactions with the facilitator and the audience. In clinical settings, a presenter uses his/her time for the preparation of case presentations to reflect on the information he/she has collected. The facilitator should know how to improve case presentations to diagnose and improve the presenter. The advantages of the short presentation should be emphasized.     

Unusual left ventricular dilatation without functional or biochemical impairment in normotensive extremely overweight Japanese professional sumo wrestlers

To explore the physiologic limit of left ventricular (LV) enlargement, we performed echocardiography and air displacement plethysmography to respectively assess LV dimension and function and the body composition of Japanese professional sumo wrestlers. After excluding subjects with cardiovascular disease, hypertension, plasma brain natriuretic peptide (BNP) > or =17.9 pg/ml, diabetes mellitus, or asthma, 331 subjects (mean +/- SD age, 21.6 +/- 3.7 years; height 179.2 +/- 5.3 cm; weight 1,17.9 +/- 21.5 kg; percent fat, 29.6 +/- 6.6%) were analyzed. LV end-diastolic dimension averaged 58.4 +/- 3.7 mm and was within the generally regarded normal limit (< or =54 mm) in 14.5% of subjects, but was > or =60 mm in 41.1% of subjects. LV septal and posterior wall thicknesses were 10.3 +/- 0.9 and 10.2 +/- 0.9 mm, respectively. Peak E- and A-wave velocities, E/A ratio, LV fractional shortening, and BNP were 96 +/- 16 and 51 +/- 13 cm/s, 2.0 +/- 0.7, 33.5 +/- 4.5%, and 3.1 +/- 3.7 pg/ml, respectively. LV end-diastolic dimension was not correlated with these indexes of LV function or with plasma BNP levels, but was significantly correlated with height, weight, body surface area, fat-free mass, and fat mass. These results show that among very large, highly trained, professional athletes, LV end-diastolic dimension frequently exceeds the traditionally accepted upper limit of normal for the general population. This increase in LV end-diastolic dimension may thus represent an extreme example of the physiologic adaptation of the athlete's heart.     

Pressure dye-spray: a simple and reliable method for differentiating adenomas from hyperplastic polyps in the colon

BACKGROUND: Based on 10 years of experience with chromoendoscopy, our hypothesis was that colonic adenomas can be differentiated from hyperplastic polyps by use of a high-pressure spray-jet of dye (pressure dye-spray). To test the accuracy of pressure dye-spray, classification of colonic polyps as adenomas and hyperplastic polyps by pressure dye-spray and ordinary colonoscopic findings (shape, size, and color surface appearance) were compared. METHODS: Pressure dye-spray chromoendoscopy was performed by using 0.035% indigo carmine, a spray-type cannula, and a water pump. Polyps were first classified as adenomas or hyperplastic polyps by ordinary colonoscopic findings. One or more pressure dye-spray bursts were then focused on the polyp from a distance of 1 to 2 cm. Polyps were classified as adenomas only if oozing of blood was evident; otherwise, they were classified as hyperplastic polyps. A histologic diagnosis was obtained for all polyps, and the results of ordinary colonoscopic findings and pressure dye-spray were compared. RESULTS: This study examined 1468 polyps (1201 adenomas, 267 hyperplastic polyps; mean diameter 4 mm). The sensitivities for polyp differentiation with pressure dye-spray and ordinary colonoscopic findings were, respectively, 97.9% and 73.4% (p < 0.0001); specificities were, respectively, 96.6% and 92.1% (p = 0.077). CONCLUSIONS: Pressure dye-spray was found to be a reliable technique for differentiation between adenomas and hyperplastic polyps.     

Clinical features of Japanese type 1 autoimmune hepatitis patients with zone III necrosis

Aim: In Caucasians in northern Europe and North America, type 1 autoimmune hepatitis is characterized by susceptibility to human leukocyte antigens DR3 and DR4, and patients with zone III necrosis more frequently have an acute onset of the disease and a lower frequency of cirrhosis than those without. In Japanese patients, however, type 1 autoimmune hepatitis is primarily associated with DR4, and there are almost no DR3-positive patients. Thus, the clinical features of Japanese patients with type 1 autoimmune hepatitis and zone III necrosis may be different from those reported previously for Caucasians. Methods: We investigated 160 consecutive patients with type 1 autoimmune hepatitis (20 males and 140 females; median age, 55 years; range, 16-79 years). Results: Forty-seven patients (29%) had zone III necrosis, and these patients had lower serum levels of albumin and higher serum levels of total bilirubin, aspartate aminotransferaseand alanine aminotransferase. Histologically, zone III necrosis was found more frequently in patients with acute hepatitis than in those with chronic hepatitis. However, there was no difference in the frequency of cirrhosis between patients with and without zone III necrosis. In addition, normalization of serum alanine aminotransferase levels within six months after the introduction of corticosteroid treatment was slightly more frequent in patients with zone III necrosis (95% vs. 88%). Conclusion: In Japanese patients, zone III necrosis may reflect not only acute autoimmune hepatitis, but also acute exacerbation of pre-existing chronic disease. Furthermore, patients with zone III necrosis may respond better to corticosteroid treatment than those without.     

Changes in calcium homeostasis in acromegaly treated by pituitary adenomectomy

Patients with acromegaly have alterations in mineral metabolism. To determine the effect of correction of excess GH secretion on calcium metabolism, we studied 12 acromegalic patients before and 3-4 weeks after pituitary adenomectomy. Treatment of acromegaly resulted in significant decreases in both serum calcium [from 9.3 +/- 0.2 to 8.7 +/- 0.1 mg/dl (mean +/- SEM); P less than 0.01] and urinary calcium excretion (from 200 +/- 24 to 88 +/- 12 mg/24 h; P less than 0.0002). Serum phosphate also decreased significantly (P less than 0.01) from 4.8 +/- 0.2 to 4.3 +/- 0.2 mg/dl. Both serum immunoreactive PTH and calcitonin levels were normal initially and did not change after surgery. The mean serum 25-hydroxyvitamin D (25OHD) level was significantly (P less than 0.01) lower and the 1,25-dihydroxyvitamin D [1,25-(OH)2D] level was significantly (P less than 0.0001) higher in acromegaly compared with measurements in 25 normal subjects. After surgery, the serum 25OHD level did not change; however, the serum 1,25-(OH)2D concentration fell significantly (P less than 0.0001) from 60 +/- 4 to 43 +/- 2 pg/ml. A positive correlation was found between the decrements in urinary calcium excretion and the serum 1,25-(OH)2D level when the comparison was made between the decrements as percentages of pretreatment values (r = 0.64; P less than 0.05). The accumulated data suggest that the hypercalciuria in acromegaly might be due to intestinal calcium hyperabsorption, which could be attributed to the elevated circulating 1,25-(OH)2D level. Excessive GH secretion might stimulate the production of 1,25-(OH)2D and might also directly stimulate calcium absorption.     

Communication Disparity Between the Bereaved and Others: What Hurts Them and What Is Unhelpful? A Nationwide Study of the Cancer Bereaved

Context

The importance of communication between the cancer bereaved and others has been emphasized, but little is known about the more problematic aspects of this communication such as “unhelpful communication.”

Effect of radioactivity outside the field of view on image quality of dedicated breast positron emission tomography: preliminary phantom and clinical studies

Annals of Nuclear Medicine - Semi-quantitative positron emission tomography (PET) values, such as the maximum standardized uptake value (SUVmax), are widely used to identify malignant lesions and...     

Identification of an oncogenic form of the thrombopoietin receptor MPL using retrovirus-mediated gene transfer

Thrombopoietin and its receptor (MPL) are important regulators of megakaryopoiesis. We have identified an activating mutation of MPL using a combination of a retrovirus-mediated gene transfer and polymerase chain reaction-driven random mutagenesis. This point mutation causes a single amino acid substitution from Ser498 to Asn498 in the transmembrane region and abrogates factor-dependency of all interleukin-3-dependent cell lines tested. Murine interleukin-3- dependent Ba/F3 cells expressing the mutated but not the normal form of MPL were tumorigenic when transduced into syngeneic mice. Analysis of intracellular signaling pathways indicated that the mutant MPL protein constitutively activated two distinct signaling pathways, SHC-Raf-MAPK and JAK2-STAT3/STAT5.