Lipid messenger, diacylglycerol, and its regulator, diacylglycerol kinase, in cells, organs, and animals: history and perspective

Diacylglycerol kinase (DGK) metabolizes diacylglycerol (DG), a glycerolipid containing two acyl chains, to convert phosphatidic acid. DG is produced through phosphoinositide turnover within the membrane and is well known to act as a second messenger that modulates the activity of protein kinase C in the cellular signal transduction. Recent studies have revealed that DG also activates several proteins, including Ras guanine-nucleotide releasing protein and ion channels such as transient receptor potential proteins. Therefore, DGK is thought to participate in a number of signaling cascades by modulating levels of DG. Previous studies have disclosed that DGK is composed of a family of the isozymes, which differ in the structure, enzymological property, gene expression and localization, subcellular localization, and binding molecules. The present review focuses on the stories of phosphoinositide turnover and DG, including historical views, structural features, metabolism, and relevant cellular phenomena, together with the characteristics of DGK isozymes and the pathophysiological findings on animal studies using knockout mice and models for human diseases. Now it is being revealed that the structural and functional diversity and heterogeneity of and around DGK support the proper arrangement of the complex signal transduction machinery.     

Prognostic Significance of Immunohistochemically Detected Blood and Lymphatic Vessel Invasion in Colorectal Carcinoma: Its Impact on Prognosis

Background The prognostic significance of blood vessel invasion (BVI) and lymphatic vessel invasion (LVI) is unclear. Because of the absence of specific markers for venous and lymphatic vessels, earlier studies could not reliably distinguish between BVI and LVI. Methods By immunostaining for podoplanin and CD34 antigen, we retrospectively investigated LVI and BVI in 419 tissue specimens of colorectal carcinoma. We performed univariate and multivariate analysis of the clinicopathologic features, frequency of recurrence, and outcome of patients with or without LVI and BVI. Results The use of hematoxylin and eosin (H&E) staining to identify BVI and LVI yielded a false positive rate of 9.1% and false negative rate of 12.6%. The incidence of BVI was significantly higher among tumors with LVI than tumors without LVI (P <.001). In logistic multivariate analysis, only LVI (P < .001) was associated with lymph node metastasis and BVI (P = .015) was associated with distant recurrence. Calculating the prognostic relevance, both two invasion types correlated with decreased survival in univariate analysis (both P <.001). In multivariate analysis, BVI (P =.024), lymph node status (P =.003) and tumor stage (P <.001) remained statistically significant factors for survival. Conclusions Our results suggest that immunohistologic evaluation of BVI and LVI could be useful in colorectal carcinoma indicating the risk of lymph node metastasis and recurrence, thereby contributing to prognostic evaluation.     

Automated quantification of left ventricular function by the automated contour tracking method

The automated contour tracking (ACT) method has been developed for the automated measurement of area volume using the energy minimization method without tracing a region of interest. The purpose of this study was to compare the ACT method and left ventriculography (LVG) for the measurement of left ventricular (LV) function in the clinical setting. An apical four-chamber view was visualized by two-dimensional echocardiography and recorded for off-line analysis in 14 patients with high-quality images who underwent LVG. The ACT method automatically traces the endocardial border from the recorded images and calculates LV volumes (end-diastole and end-systole) and ejection fraction (EF). Both ACT and LVG were compared by linear regression analysis for the measurement of EF. EF determined by the ACT method agreed well with that by LVG (r = 0.96, y = 0.94x + 4.6, standard error of the estimate = 3.9%). The mean difference between the ACT and LVG was -1.4%+/- 7.3%.In conclusion, the ACT method is reliable for noninvasive estimation of EF in high-quality images. This suggests that this new technique may be useful in the automated quantification of LV function.     

Overt bone metastasis and bone marrow micrometastasis of early gastric cancer

Recently we encountered two cases of early gastric cancer (EGC) with bone metastasis after surgery. As they were not accompanied by overt liver, lung, or peritoneal metastasis, we examined the clinical significance of bone metastasis in EGC and its mechanisms by a review of the literature. We found only 10 cases of EGC complicated with overt bone metastasis in the English literature, so we also examined the Japanese reports of such cases. The main histologic type of cases of bone metastasis from EGC was the diffuse type, and there were long intervals between surgery and overt bone metastasis. One reason for such long intervals may have been the tumor dormancy. Two types of dormancy, dynamic and static, and two types of postoperative overt metastases, that of micrometastatic origin (normograde metastatic process) and that of bone marrow origin (retrograde metastatic process), were considered. We speculated that there may be specific routes by which the cancer cells infiltrate the bone marrow directly from EGC or lymph node metastasis. The procedures for diagnosing bone micrometastasis using monoclonal antibodies have recently been improved, but their accuracy rates are still not universally accepted. New, more reliable examinations are required to improve the survival rates of EGC.     

Brain trauma induces expression of diacylglycerol kinase ζ in microglia

Diacylglycerol kinase (DGK) is an enzyme which phosphorylates a second messenger diacylglycerol and consists of a family of isozymes that differ in terms of structural motifs, enzymological property, and cell and tissue distribution. One of the isozymes, DGKζ was originally shown to be expressed in various kinds of neurons under physiological conditions. However, we unexpectedly found that under pathological conditions, such as cerebral infarction, DGKζ-immunoreactivity is detected in non-neuronal cells, although it remained to be elucidated in detail which cell types are responsible for the induced expression of DGKζ in this setting. To further elucidate functional implications of DGKζ in non-neuronal cells we performed detailed immunohistochemical analysis of DGKζ using rat brain cryoinjury model. As early as 1 h after cryoinjury, DGKζ-immunoreactivity was greatly decreased in the afflicted cerebral cortex and almost disappeared in the necrotic core. On day 7 after cryoinjury, however, DGKζ-immunoreactivity reappeared in this area. DGKζ-immunoreactivity was clearly detected in Iba1-immunoreactive cells of an oval or ameboid shape in the scar region, which represent activated microglia and/or macrophages. On the other hand, DGKζ-immunoreactivity was not detected in Iba1-immunoreactive, resting microglia of ramified and dendritic configuration in the intact cortex. Furthermore, DGKζ-immunoreactive cells were also positive for a microglia marker GLUT5 in the scar region, but never for an astrocyte marker GFAP. Taken together, the present study reveals that DGKζ is induced in activated microglia in brain trauma, suggesting the functional significance of DGKζ in this process.     

In vitro study of the effect of raloxifene on lipid metabolism compared with tamoxifen

OBJECTIVE: Tamoxifen and raloxifene, selective estrogen receptor modulators, decrease serum concentrations of total cholesterol; however, the effect of these drugs on triglyceride metabolism is unclear. In the present study, we investigated the in vitro effect of raloxifene on lipid metabolism and compared it with that of tamoxifen. DESIGN AND METHODS: Intracellular concentrations of total cholesterol and triglyceride in HepG2 cells were measured by an enzymatic method after tamoxifen or raloxifene treatment with or without oleic acid and with or without very low density lipoprotein. RESULTS: Intracellular concentrations of total cholesterol and triglyceride without oleic acid or very low density lipoprotein were not significantly different after treatment with tamoxifen or raloxifene. In contrast, although raloxifene with oleic acid did not increase the intracellular concentrations of triglyceride, tamoxifen treatment in the presence of oleic acid or very low density lipoprotein significantly increased (P<0.05) the triglyceride concentrations. CONCLUSION: The present study suggests that raloxifene does not increase intracellular triglyceride in the presence of oleic acid or very low density lipoprotein, in contrast to tamoxifen. Therefore, raloxifene might be safer than tamoxifen for treating patients with unstable triglyceride levels or a history of hypertriglyceridemia.     

Immunological Abnormalities in Kawasaki Disease with Coronary Artery Lesions

A review of our previous immunological studies on Kawasaki disease (KD) was undertaken. The results showed that peripheral blood macrophages/monocytes, T-cells and B-cells become activated during acute KD in terms of numerical changes in immunocompetent cells, expression of activated antigens on the cell surfaces and cytokine production. Also, during acute KD with coronary artery lesions (CALs) the numbers of macrophages/monocytes are increased. In addition, both the increased levels of tumor necrosis factor-α and shed intercellular adhesion molecule-1 in serum are more evident in KD patients with CALs than in those without. Our results further suggest that the main characteristics of the pathogenesis of KD are increased numbers of peripheral blood macrophages/monocytes with the secretion of monokines by these activated cells, and the expression of adhesion molecules on immunocompetent cells. These immune responses develop more vigorously in KD patients with CALs.     

Single burr hole evacuation for traumatic acute subdural hematoma of the posterior fossa in the emergency room

A 57-year-old man and a 55-year-old man presented with acute subdural hematoma of the posterior cranial fossa due to trauma. Both were comatose preoperatively. Emergent single burr hole evacuation in the posterior cranial fossa was performed in the emergency room immediately after computed tomography. Neurological symptoms improved dramatically just after initiating the burr hole evacuation in both patients. A 57-year-old man became alert and could walk unassisted 1 month after surgery. The other could walk with assistance 4 months after surgery, although psychic disturbance resulting from cerebral contusion remained. Single burr hole evacuation in the emergency room is a useful treatment for acute subdural hematoma of the posterior cranial fossa because the procedure can be performed easily and rapidly, thus achieving reduction of intracranial pressure. Progressing neurological deterioration, reversibility of brainstem function by mannitol administration and the sign of brainstem compression and noncommunicating hydrocephalus are good indicators for this treatment.