Kazuhiro Masui

Prognostic value of increased plasma levels of brain natriuretic peptide in patients with septic shock.

ABSTRACT Our objective was to investigate the plasma levels of brain and atrial natriuretic peptides (BNP and ANP, respectively) in patients with septic shock/severe sepsis and to study the association of BNP and ANP levels with hemodynamic parameters, severity of the disease, and prognosis of those patients. This is a prospective case series study of 22 patients with septic shock, 11 patients with severe sepsis, and 20 healthy volunteers at the Department of Emergency and Critical Care Medicine, Nara Medical University Hospital, Japan. Blood collection was performed on admission and on days 1, 2, and 4. Plasma BNP and ANP levels were measured by radioimmunoassay. Right atrial pressure, mean pulmonary arterial pressure, pulmonary arterial wedge pressure, and left ventricular stroke work index were determined using a thermodilution catheter. Acute Physiological and Chronic Health Evaluation II scores were calculated. Plasma levels of BNP and ANP were markedly elevated in patients with septic shock/severe sepsis compared with controls (BNP, 7 ± 0.3 pg mL−1; ANP, 13 ± 1 pg mL−1). In patients with septic shock, both BNP and ANP peaked on day 2 (BNP, 987 ± 160 pg mL−1; ANP, 103 ± 17 pg mL−1). Plasma levels of BNP on day 2 in patients with septic shock significantly correlated with right atrial pressure (r = 0.744, P < 0.01), mean pulmonary arterial pressure (r = 0.670, P < 0.01), pulmonary arterial wedge pressure (r = 0.709, P < 0.01), left ventricular stroke work index (r = −0.552, P < 0.05), Acute Physiological and Chronic Health Evaluation II score (r = 0.581, P < 0.01), and poor prognosis (P < 0.05). The optimal cutoff point for predicting mortality in patients with septic shock was a BNP level of 650 pg mL−1 on day 2, in which sensitivity and specificity were 92% and 80%, respectively. Increased plasma levels of BNP may reflect not only the severity of myocardial depression but also the disease severity and could be of prognostic value in patients with septic shock.

Cytosine deaminase/5-fluorocytosine gene therapy can induce efficient anti-tumor effects and protective immunity in immunocompetent mice but not in athymic nude mice

Murine hepatocellular carcinoma cells were retrovirally transduced with the bacterial cytosine deaminase (CD) gene. CD‐transduced cells exhibited more than 120‐fold higher sensitivity to 5‐fluorocytosine (5‐FC) compared with parental cells. When syngeneic immunocompetent mice were inoculated s.c. with parental hepatocellular carcinoma cells containing as little as 5% CD‐transduced cells, significant inhibition of tumor formation was induced by 5‐FC treatment. Furthermore, established solid tumors in immunocompetent mice containing only 5% CD‐transduced cells were infiltrated markedly with CD4+ and CD8+ T lymphocytes and macrophages by 5‐FC treatment, such that significant reduction or even complete regression of tumors was observed. These tumor‐free mice resisted subsequent rechallenge with wild‐type tumor. Conversely, when athymic nude mice were inoculated with a cell mixture containing CD‐transduced cells and parental cells at a ratio of 40:60, all developed tumors despite 5‐FC treatment. Our results indicate that gene therapy using the CD/5‐FC system can induce efficient anti‐tumor effects and protective immunity in immunocompetent mice but not in athymic immunodeficient mice, suggesting that the hosts immunocompetence may be a critical factor for achieving successful gene therapy against cancer. Int. J. Cancer 81:592–597, 1999.

Complete cure of established murine hepatocellular carcinoma is achievable by repeated injections of retroviruses carrying the herpes simplex virus thymidine kinase gene

Although xenotransplantation of retrovirus-producing cells into a tumor has been shown to be effective for the treatment of cancer, injections of recombinant retroviruses are much more feasible for clinical applications. We established a clone producing retroviruses carrying the herpes simplex virus thymidine kinase (HSVtk) gene with titers of up to 4 × 107 colony-forming units/ml, and examined the effectiveness of in vivo gene therapy against cancer. Syngeneic mice were inoculated subcutaneously with murine hepatocellular carcinoma (HCC) cells, BNL1ME A.7R.1, and the treatment was initiated after tumors were established. When mice were given an intratumoral injection of HSVtk-carrying retroviruses or their producing cells followed by ganciclovir (GCV) treatment, significantly pro- longed survival periods were observed. When mice were treated with repeated intratumoral injections of HSVtk-carrying retrovirus-producing cells, significant antitumor responses and some cures were induced by GCV treatment. Furthermore, repeated intratumoral injections of HSVtk-carrying retroviruses and GCV treatment resulted in complete regression of established HCC tumors in all animals used in the experiment. Mice that completely eradicated tumors exhibited protective immunity against wild-type HCC tumors. These results suggest that repeated injections of HSVtk-carrying retroviruses followed by GCV treatment is a potent modality for the treatment of solid tumors.

Tissue-specific expression of HSV-tk gene can induce efficient antitumor effect and protective immunity to wild-type hepatocellular carcinoma.

The efficacy of expression of the herpes simplex virus thymidine kinase (HSV‐tk) gene under the transcriptional control of the liver‐specific albumin gene promoter, followed by ganciclovir treatment, was investigated both in vitro and in vivo. Murine and rat hepatocellular carcinoma (HCC) cells infected with retroviruses carrying the HSV‐tk gene under the control of the murine albumin gene promoter were selectively killed by ganciclovir treatment in vitro, whereas non‐HCC cells, such as murine mammary tumor cells and fibroblast cells, which were infected with the same retroviruses, were not. Susceptibility of the retroviral‐infected HCC cells to ganciclovir was more than 100‐fold higher than that of the retroviral‐infected non‐HCC cells. When mice bearing a bulky HCC mass consisting of the retroviral‐infected HCC cells were treated with systemic ganciclovir administration, complete regression of the tumors was observed without any signs of overt toxicity. Profound antitumor effects on preestablished murine HCCs were observed when wild‐type HCC cells were implanted into animals with a small percentage of the retroviral‐infected counterparts. When only 5% of the cells were infected with retroviruses carrying the HSV‐tk gene, significant inhibition of tumor development was observed with systemic ganciclovir treatment. Importantly, animals that were treated with implantation of mixtures of the retroviral‐infected and parental HCC cells, followed by ganciclovir administration, did not exhibit tumor formation and resisted subsequent rechallenge with wild‐type HCC cells. Our results indicate the feasibility of combination therapy with the HSV‐tk gene and ganciclovir for the treatment of HCC. Int. J. Cancer 71:470‐475, 1997.

Pancreatic pleural effusion with a pancreaticopleural fistula diagnosed by magnetic resonance cholangiopancreatography and cured by somatostatin analogue treatment.

AbstractA 69-year-old man with chronic alcoholic pancreatitis developed a left-sided massive pleural effusion. Magnetic resonance cholangiopancreatography clearly demonstrated the pancreatic cyst and the fistula connecting the cyst with the left pleural cavity, resulting in the diagnosis of pancreatic pleural effusion with a pancreaticopleural fistula. Conservative somatostatin analogue treatment completely eradicated the pancreatic pleural effusion and closed the pancreaticopleural fistula.

Construction of retroviral vectors to induce strong hepatoma cell-specific expression of cytokine genes

Continuing advances in molecular biology have provided tools for a promising approach to the treatment of cancer. Among the various strategies of gene therapy for cancer, many are aimed at killing tumour cells indirectly by the induction or reinforcement of a host immune response by gene transduction of various cytokines, major histocompatibility complex or immune accessory molecules. In the present study, we selected the tumour necrosis factor‐α, interleukin‐2 and interleukin‐3 genes as potential cytokine genes to induce antitumour effects. We constructed retroviral vectors carrying these cytokine genes under the control of the murine albumin enhancer and promoter and retrovirally transduced these genes into hepatoma and non‐hepatoma cell lines. Strong expression of the cytokine genes was induced in transduced hepatoma cells, while no evident expression was detected in transduced non‐hepatoma cells. These results demonstrate the hepatoma‐specific expression of cytokine genes and imply the feasibility of in vivo gene transfer into hepatomas without affecting any other tissues. Furthermore, these cytokine genes were expressed much more intensively when they were derived from the albumin enhancer and promoter than when derived from the simian virus 40 early region promoter. These results indicate that transcriptional regulatory sequences specific for the target tissues could be preferable to viral promoters for the gene therapy of cancer.

Bacterial cytosine deaminase suicide gene transduction renders hepatocellular carcinoma sensitive to the prodrug 5-fluorocytosine

Abstract One of the most promising approaches to the treatment of cancer is to render tumor cells susceptible to normally non-toxic chemotherapeutic agents utilizing so-called ‘suicide genes’. The herpes simplex virus thymidine kinase gene is a prototypic suicide gene and clinical trials of gene therapy using it have already been approved for the treatment of glioma and ovarian cancer. We previously demonstrated that transduction of the herpes simplex virus thymidine kinase gene into hepatocellular carcinoma (HCC) cells resulted in the selective killing of transduced cells by ganciclovir treatment. There is, however, another potential suicide gene. Bacterial cytosine deaminase (CD) converts the innocuous compound 5-fluorocytosine (5-FC) to the highly toxic compound 5-fluorouracil (5-FU). Attractively, both compounds have been clinically available so that much is known of their pharmacokinetics. We transferred the bacterial CD gene with a retroviral vector into HCC cells and determined the sensitivity to 5-FC. Transduced HCC cells were susceptible to 5-FC toxicity in a dose-dependent manner and exhibited 0% survival at a 5-FC concentration of 100 μg/ml, while untransduced cells exhibited nearly 100% survival at the same concentration. Sensitivity of the former cells to 5-FC was approximately 100-fold higher than the latter cells, indicating the feasibility of this strategy for the treatment of HCC. Furthermore, it was demonstrated that bacterial CD genetransduced HCC cells eliminated untransduced cells in the presence of 5-FC whose concentration was essentially non-toxic to untransduced cells. This phenomenon, the so-called ‘bystander effect’, provides therapeutic advantages for gene therapy for cancers, even if it is impossible to introduce a foreign gene into all target cells of a cancer. These results demonstrate that retroviral-mediated bacterial CD gene transfer has potential for the treatment of HCC.

A case of early gastric malignant lymphoma diagnosed and completely resected by strip biopsy

A case of early gastric malignant lymphoma definitively diagnosed by strip biopsy is reported. The subsequent operation revealed that the strip biopsy had resulted in radical resection. A 55-year-old woman visited our hospital for detailed examination of a small gastric lesion. Histologic findings of the specimens obtained by conventional forceps biopsy indicated reactive lymphoid hyperplasia, although the possibility of malignant lymphoma was not completely ruled out. Strip biopsy was, therefore, performed to establish a definitive diagnosis. Histopathological examinations of the strip biopsy specimen revealed definitive findings of malignant lymphoma, which was B-cell phenotype immunocytochemically. The margin of the resected specimen was free of invasion by malignant lymphoma and no lymph node involvement was suggested by endoscopic ultrasonography, computed tomography, and gallium scintigram. Subtotal gastrectomy was subsequently performed to rule out the possibility of remaining malignant lymphoma cells. It was proven that the strip biopsy removed the lesion completely and no perigastric lymph nodes were involved. While is still controversial as to whether strip biopsy should be adopted for the radical resection of early gastric lymphoma, this procedure can definitely provide excellent specimens for the accurate diagnosis of gastric malignant lymphoma and probably for group III lesions in the stomach.