The use of yeast to understand TRP-channel mechanosensitivity

Mechanosensitive (MS) ion channels likely underlie myriad force-sensing processes, from basic osmotic regulation to specified sensations of animal hearing and touch. Albeit important, the molecular identities of many eukaryotic MS channels remain elusive, let alone their working mechanisms. This is in stark contrast to our advanced knowledge on voltage- or ligand-sensitive channels. Several members of transient receptor potential (TRP) ion channel family have been implicated to function in mechanosensation and are recognized as promising candidate MS channels. The yeast TRP homolog, TRPY1, is clearly a first-line force transducer. It can be activated by hypertonic shock in vivo and by membrane stretch force in excised patches under patch clamp, making it a useful model for understanding TRP channel mechanosensitivity in general. TRPY1 offers two additional research advantages: (1) It has a large (∼300 pS) unitary conductance and therefore a favorable S/N ratio. (2) Budding yeast allows convenient and efficient genetic and molecular manipulations. In this review, we focus on the current research of TRPY1 and discuss its prospect. We also describe the use of yeast as a system to express and characterize animal TRP channels.     

Differential cell-specific location of Cav-1 and Ca2+-ATPase in terminal Schwann cells and mechanoreceptive Ruffini endings in the periodontal ligament of the rat incisor

Caveolae are involved in clathrin-independent endocytosis, transcytosis, signal transduction, and tumor suppression – all of which depend on their main constituent protein caveolin families. The periodontal Ruffini ending has been reported to develop a caveola-like structure on the cell membrane of both the axon terminals and Schwann sheaths, suggesting the existence of an axon–Schwann cell interaction in the periodontal Ruffini endings. However, little information is available concerning the functional significance of these caveolae. The present study was undertaken to examine the immunolocalization of caveolin-1, -3 (Cav-1, Cav-3) and Ca²⁺-ATPase in the periodontal Ruffini endings of the rat incisor. Decalcified sections of the upper jaws were processed for immunocytochemistry at the levels of light and electron microscopy. Some immunostained sections were treated with histochemistry for nonspecific cholinesterase (nChE) activity. Observations showed the periodontal Ruffini endings were immunopositive for Cav-1, but not Cav-3. Immunoreactive products for Cav-1 were confined to caveola-like structures in the cell membranes of the cytoplasmic extensions and cell bodies of the terminal Schwann cells associated with the periodontal Ruffini endings. However, the axonal membranes of the terminals did not express any Cav-1 immunoreaction. Double staining with Ca²⁺-ATPase and either protein gene product 9.5 (PGP 9.5) or S-100 protein disclosed the co-localization of immunoreactions in the axonal branches of the periodontal Ruffini endings, but not in the terminal Schwann cells. As Ca²⁺ plays an important role in mechanotransduction, these characteristic immunolocalizations show Cav-1/Ca²⁺-ATPase might be involved in the quick elimination of intracellular Ca²⁺ in mechanotransduction.     

Soluble E-selectin, leptin, triglycerides, and insulin resistance in nonobese Japanese type 2 diabetic patients

The aim of the present study was to investigate the relationships between insulin resistance and soluble E-selectin, body mass index (BMI), leptin, and serum lipid profile including triglycerides in nonobese Japanese type 2 diabetic patients. A total of 97 nonobese Japanese type 2 diabetic patients aged 43 to 84 years were examined. The duration of diabetes was 11.2 +/- 0.8 years. In conjunction with BMI and fasting concentrations of plasma glucose, serum lipids (triglycerides, total cholesterol, and high-density lipoprotein cholesterol) and serum insulin, soluble E-selectin, and leptin were also measured. The low-density lipoprotein (LDL) cholesterol level was calculated using the Friedewald formula. Insulin resistance was estimated by the homeostasis model assessment. The subjects were divided into 2 groups according to the value of insulin resistance estimated by the homeostasis model assessment. Values greater than 2.5 were indicative of the insulin-resistant state, and values less than 2.5 were indicative of the insulin-sensitive state. The insulin-resistant group had significantly higher levels of E-selectin, leptin, triglycerides, total and LDL cholesterol, and diastolic blood pressure as compared with the insulin-sensitive group. There was, however, no significant difference in age, sex, diabetes duration, BMI, systolic blood pressure, HbA1c, and high-density lipoprotein cholesterol between the 2 groups. Univariate regression analysis showed that insulin resistance was positively correlated to E-selectin (r = 0.305, P = .003), BMI (r = 0.283, P = .006), leptin (r = 0.296, P = .004), HbA1c (r = 0.241, P = .018), serum triglycerides (r = 0.385, P < .001), serum total (r = 0.240, P = .019) and LDL cholesterol (r = 0.254, P = .013) levels, and systolic (r = 0.247, P = .024) and diastolic (r = 0.305, P = .006) blood pressure. Multiple regression analyses showed that insulin resistance was independently predicted by serum E-selectin (F = 18.4), serum leptin (F = 14.0) and serum triglycerides (F = 20.0) levels, which explained 45.0% of the variability of insulin resistance. From these results, it can be concluded that in conjunction with serum triglycerides and serum leptin, serum E-selectin is another important independent factor associated with insulin resistance in nonobese Japanese type 2 diabetic patients.     

Endoscopic submucosal dissection for cancers of the remnant stomach after distal gastrectomy

BACKGROUND: Endoscopic submucosal dissection (ESD) of early gastric cancer is less invasive than surgical resection, and if technically feasible, it may result in less long-term morbidity than does incisional surgery. However, ESD is technically difficult in patients who have had a previous distal gastrectomy. OBJECTIVE: Our purpose was to retrospectively assess the results of ESD of early gastric cancer in the remnant stomach. DESIGN: Case series. SETTING AND PATIENTS: A total of 31 lesions in 30 patients with early remnant gastric cancer were treated with ESD at Okayama University Hospital, Tsuyama Central Hospital, Hiroshima City Hospital, Kagawa Prefectural Central Hospital, and Mitoyo General Hospital from March 2001 to January 2007. INTERVENTION: ESD. MAIN OUTCOME MEASUREMENTS: En bloc resection rate, complete resection rate, operation time, and complications. RESULTS: En bloc resection and complete resection were achieved in 30 (97%) and in 23 (74%) lesions, respectively. The median operation time required for ESD in the remnant stomach was 113 minutes (range 45-450 minutes). Perforation occurred in 4 (13%). The incidence of delayed bleeding requiring blood transfusion was 0%. LIMITATION: Short duration of follow-up. CONCLUSIONS: ESD is feasible in the remnant stomach but has a relatively high complication rate and should only be performed by experienced endoscopists.     

Protein-losing gastropathy associated with autoimmune disease: successful treatment with prednisolone

99m Tc-labeled human serum albumin scintigram showing abnormal radioactivity in the stomach. Endoscopic gastric biopsies revealed nonspecific inflammation, but marked intramural edema. Based on a slight elevation of antinuclear antibody level, autoimmune disease was suspected to be involved in this patient. Administration of prednisolone, as a diagnostic therapy, alleviated the hypoproteinemia, hypoalbuminemia, and hypercholesteremia. These findings suggest that an autoimmune mechanism could have been involved in this case of protein-losing gastropathy. Received: September 4, 2000 / Accepted: February 23, 2001     

Substance P containing nerve fibers in rectal mucosa of ulcerative colitis

BACKGROUND AND PURPOSE: The intestine is rich in peptidergic innervation, which modulates mucosal immune responses. Among neuropeptides, substance P (SubP) has received considerable attention for stimulatory effects on various immunocytes in inflammatory diseases. In our prior study, we demonstrated increased innervation of SubP containing nerve fibers (SubP fibers) in ulcerative colitis (UC) surgically resected colonic specimens. In the present study, we examined the alterations of SubP fibers among various subgroups of UC, divided according to clinicopathologic features. METHODS: Distribution of SubP fibers were examined immunohistochemically in the rectal biopsy specimens of UC. The UC group was further divided into subgroups according to six clinicopathologic parameters. The linear density of SubP fibers was measured by digitalized morphometry for quantitative analysis. RESULTS: Multivariate analysis revealed significant correlations between linear density of SubP fibers vs.activity of diseases and total dose of prednisolone. Linear density was significantly increased in active cases of UC (active UC, 22.6±1.6 μm/1,000 μm ²;vs.inactive UC, 12.2±0.8 μm/1,000 μm ²;P<0.01). Furthermore, the increase was pronounced in cases that showed persistent inflammation and, accordingly, needed a high dose or continuous administration of prednisolone. CONCLUSION: Alterations in SubP fibers appear to play an important role in the pathogenesis of UC.     

A successful case of varix of the left gastroepiploic vein preoperatively diagnosed by 3D-CT angiography and resected by laparoscopy: A case report

Introduction:Gastric varices can be present in up to 20% of patients with portal hypertension. However, a varix of the left gastroepiploic vein (LGV) is extremely rare. Surgery is required if bleeding occurs; thus, precise diagnosis is crucial. We present a successful case of preoperative diagnosis intraabdominal varix of the LGV using three-dimensional-computed tomography angiography (3D-CTA) followed by laparoscopic resection. This is the first report of a case with variant LGV. Our study demonstrates the efficacies of 3D-CTA and laparoscopic surgery for the diagnosis and safe resection of the intraabdominal varix, respectively.Patient concerns:A 74-year-old woman was referred to our department with a tumor in the abdominal cavity. On physical examination, no lumps were palpable in the upper abdomen.Diagnosis:The enhanced CT was revealed that the tumor was not enhanced in the early phase, but in the equilibrium phase. Moreover, 3D-CTA clearly revealed that the tumor was being supplied by the LGV. Thus, it was diagnosed as a variant of the LGV.Interventions:Surgical resection was performed laparoscopically as per the guidance of preoperative 3D-CTA findings. During surgery, a dark tumor was found along the gastroepiploic vessels, supplied by the LGV. The tumor was resected safely based on the preoperative information.Outcomes:Histopathological examination of the tumor showed accumulation of various vessels, but no malignant cells. Therefore, we made a final diagnosis of the tumor as an LGV varix. For follow-up, an annual CT examination was performed and after 3 years postoperation, no recurrence was observed.Conclusions:In the present case, we have achieved a successful preoperative diagnosis using 3D-CTA, and resection was safely accomplished using laparoscopy guided by preoperative anatomical information. This is the first report of an LGV variant. Appropriate management is crucial because bleeding is a catastrophic event. Therefore, imaging procedures such as 3D-CTA for diagnosis, followed by safe resection by laparoscopic surgery, are effective tools for the treatment of epiploic vein varices.     

Pediatric myositis ossificans mimicking osteosarcoma

Myositis ossificans (MO) is a rare benign cause of heterotopic bone formation in soft tissue that most commonly affects young adults, typically following trauma. We report the case of an 11‐year‐old girl who developed MO mimicking osteosarcoma in her right shoulder. Plain radiography and computed tomography showed poorly defined flocculated densities in the soft tissue and a periosteal reaction along the proximal humerus. On magnetic resonance imaging, the mass displayed an ill‐defined margin and inhomogeneous signal change. Histologically, the mass had a pseudosarcomatous appearance. Based on these findings, the patient was initially misdiagnosed with osteosarcoma at another hospital. The diagnosis was difficult because the patient was 11 years old and had no trauma history, with atypical radiographic changes and a predilection for the site of origin for osteosarcomas. We finally made the correct diagnosis of MO by carefully reviewing and reflecting on the pathological differences between stages.     

Suppressive effect of ethanol on the expression of hepatic asialoglycoprotein receptors augmented by interleukin-1β, interleukin-6, and tumor necrosis factor-α

Blood levels of inflammatory-related cytokines, including interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α, are elevated in patients with alcoholic liver diseases. We investigated the effects of these cytokines and ethanol on the expression of hepatic asialoglycoprotein receptors (AGPRs) in a human hepatoblastoma cell line, HepG2. An [¹²⁵I]-asialo-orosomucoid binding assay showed significant increases in surface AGPR numbers in HepG2 cells by treatment with IL-1β, IL-6, and TNF-α, to levels which were approximately 130% of the values in untreated control cells. However, the enhanced AGPR numbers induced by treatment with these cytokines were markedly suppressed, to 70%–80% of the number in the untreated cells, by treatment with ethanol. Immunological detection of AGPR with a specific antibody demonstrated that the modulation of surface AGPR numbers was correlated with the cellular expression levels of AGPR. These results suggest that, although IL-1β, IL-6, and TNF-α stimulate the synthesis of hepatic AGPR, ethanol suppresses the expression of AGPR augmented by these cytokines. This leads to an increase in serum asialo-orosomucoid levels caused by the disordered catabolism mediated by AGPR in patients with alcoholic liver disease. (Received Dec. 5, 1997; accepted May 22, 1998)