Contribution of toxicologic pathologists for the safety of human health in biomedical research-past, present, and future of the JSTP.

The research field of "Toxicologic Pathology" evaluates potentially toxic chemical exposures and chemically mediated illnesses in humans and experimental animals. Comparative studies of chemical exposures between model organisms and humans are essential for the risk assessment of chemicals and human health. Here we review the development and activities of the Japanese Society of Toxicologic Pathology (JSTP) during its 37-year history. Toxicological pathology studies provide many interesting and valuable findings. Rodent cancer bioassay data demonstrate the importance of dose levels, times, and duration of exposures to chemicals that possibly cause human cancers. Studies of toxic injuries in the nasal cavity demonstrate that specific chemical compounds affect different target cells and tissues. These observations are relevant for current air pollution studies in the preventive medicine field. Future toxicological pathology studies will be enhanced by applying molecular pathology with advanced observation techniques. In addition to the nasal cavity, another sense organ such as the tongue should be a potential next program of our mission for risk assessment of inhaled and ingested chemicals. As a message to the younger members of the JSTP, interdisciplinary and global cooperation should be emphasized. Elucidating the mechanisms of toxicologic pathology with a combination of advanced expertise in genetics and molecular biology offers promise for future advances by JSTP members.

[How to reduce unnecessary orders of laboratory tests].

The medical insurance system in Japan has been focusing on how to reduce the annual increases in medical expenses. In this context, the circumstances in the laboratory department in large hospitals have been growing more strict. Therefore, medical staff working in large hospitals need to know how to reduce the expenditure consumed in laboratory tests. In this paper we report economical loss resulted from physicians' excessive test-orders and suggest how to manage the problem.

Neuroimaging and histopathological evaluation of delayed neurological damage produced by artificial occlusion of the middle cerebral artery in Cynomolgus monkeys: establishment of a monkey model for delayed cerebral ischemia.

A monkey model (Cynomolgus) was established to evaluate the delayed neurological damage evident at areas distant from ischemic cerebral foci. In addition to proton magnetic resonance spectroscopy (MRS) monitoring in life, histological examinations of specimens of the brain was conducted on lesions produced 6h and 1, 2, 4 and 8 weeks after unilateral (left) permanent middle cerebral artery occlusion (pMCO) on five monkeys. In addition to the typical images evident at primary ischemic foci around the middle cerebral artery, MRS revealed and enhanced, clearer region, due to edema extending into the reticular and compact area of the left substantia nigra one week after pMCO, inducing right hemiparesis caused by focal cerebral ischemia. Similar histological lesions were also induced in the left thalamus 4 weeks after pMCO. Thereafter, a variety of histological findings including astrocytic activation, reduced number of nerve cells and gliosis were found in the above described areas far apart from the original ischemic cerebral foci. Our monkey model should be suitable for studies elucidating the pathological process in cerebral ischemia as well as for investigating therapeutic strategies involving ischemic stroke in humans.

Acute toxicity of pierisin-1, a cytotoxic protein from Pieris rapae, in mouse and rat.

To investigate the toxicity of pierisin-1, a cytotoxic protein present in the cabbage butterfly, Pieris rapae, pierisin-1 was administered via intraperitoneally in mice and rats and the effects examined. Common findings in these experiments were hypoactivity with a gradual decrease in body weight due to decreased food intake, relative polycythemia with low serum albumin concentration and atrophy of the thymus, spleen, seminal vesicles and adipose tissue. Characteristic findings were diarrhea, fusion and atrophy of the villi and dilatation of the crypts in the small intestine at 6-100 microg/kg in BALB/c mice as well as elevation of LDH activity and creatinine value, hemolysis and renal and hepatic injuries at 1,000 and 10,000 microg/kg in BALB/c mice. In the case of ICR mice, severer renal injury was observed. On the other hand, in Fischer 344/Du rats, sudden stop of food intake, elevation of both AST and ALT activities, interlobar adhesion of the right hepatic lobe, capsular thickening, septal fibrosis and single cell necroses of subcapsular hepatocytes in the liver and basophilic tubules in the kidneys were observed. Oral administration of pierisin-1 at a dose of 10,000 microg/kg in BALB/c mice did not exert any obvious effects. Thus, existence of species and strain differences in toxicity of pierisin-1 to animals was demonstrated.

Results of a phase I clinical study using autologous tumour lysate-pulsed monocyte-derived mature dendritic cell vaccinations for stage IV malignant melanoma patients combined with low dose interleukin-2.

We conducted a pilot study to assess the feasibility and efficacy of immunotherapy for stage IV malignant melanoma patients resistant to conventional therapies involving vaccination with mature dendritic cells (mDCs) combined with administration of low dose interleukin-2. Autologous monocytes were harvested from a single apheresis and cultured for 7 days with granulocyte-macrophage colony-stimulating factor and interleukin-4, yielding immature dendritic cells (iDCs), which were then cryopreserved until use. For 4 days prior to vaccination, iDCs were exposed to autologous tumour lysate combined with tumour necrosis factor-alpha to induce terminal differentiation into mDCs. Patients were then vaccinated weekly with 107 mDCs for 10 weeks and given 350-700 kIU of interleukin-2 three times per week. Of the 10 patients in the study, one showed stable disease, seven showed progressive disease, and two showed mixed responses, including partial tumour regression, and were therefore given 20 additional injections. Only minimal adverse events were noted, including localized skin reactions and mild fever (NIH-CTC grade 0-1). Median survival from the first vaccination was 240 days (range 31-735 days). In vitro, melanoma patient-derived dendritic cells (DCs) showed reduced cell surface expression of CD1a antigen on iDCs and reduced CD86 and HLA-DR expression on mDCs. In addition, antigen uptake, chemotaxis and antigen presentation were all attenuated in DCs from the patients. In summary, although improvement of clinical efficacy will require further research, autologous tumour lysate-pulsed monocyte-derived mDCs could be safely harvested, cryopreserved and administrated to patients without obvious complications.

Foundation and progress of Japanese society of toxicologic pathology*.

The Japanese Society of Toxicologic Pathology (JSTP) has a differing conceptual framework from the Japanese Society of Pathology (JSP) and Japanese Society of Toxicology (JST) and was founded in 1985 by the leadership of late Dr. Yasukazu Nishiyama with the cooperation of several founding members and the support of JSP. The aim of the JSTP is to improve the human and animal health using an interdisciplinary scientific approach based on pathology and toxicology. In its development as a professional society, the JSTP has established society rules and activities. The JSTP has grown in terms of membership and financial aspects and is now recognized not only domestically but also internationally as a well-organized scientific society. To maintain the high professional standard and visibility of JSTP, we here provide the historical background of the society as a basis for current members to contribute to the continued improvement of our scientific organization.

Risk of human health by particulate matter as a source of air pollution--comparison with tobacco smoking.

Increased air pollution, containing carcinogenic particulate matter smaller than 2.5 microm (PM(2.5)), has gained particular attention in recent years as a causative factor in the increased incidence of respiratory diseases, including lung cancer. Extensive carcinogenicity studies conducted recently under Good Laboratory Practice conditions by National Toxicology Program in the USA, Ramazzini Foundation in Italy or Contract Research Organizations on numerous chemical compounds have demonstrated the importance of considering dose levels, times and duration of exposure in the safety evaluation of carcinogenic as well as classical toxic agents. Data on exposure levels to chemical carcinogens that produce tumor development have contributed to the evaluation of human carcinogens from extrapolation of animal data. A popular held misconception is that the risk from smoking is the result of inhaling assorted particulate matter and by products from burning tobacco rather than the very low ng levels of carcinogens present in smoke. Consider the fact that a piece of toasted bread contains ng levels of the carcinogen urethane (ethyl carbamate). Yet, no one has considered toast to be a human carcinogen. Future human carcinogenic risk assessment should emphasize consideration of inhalation exposure to higher levels of benzo (a) pyrene and other possible carcinogens and particulate matter present in polluted air derived from automobile exhaust, pitch and coal tar on paved roads and asbestos, in addition to other environmental contaminant exposure via the food and drinking water.

Experimental study of polarity in reversing cable nerve grafts.

To evaluate the effect of cable nerve graft polarity, the bilateral common peroneal nerves in 12 rabbits were excised to create 20-mm nerve gaps. These gaps were repaired with cable grafts using three strands of 20-mm ipsilateral sural nerves. In the left leg, the sural nerves were grafted with the original orientation. In the right leg, the nerve graft polarity was reversed 180 degrees. Six months later, motor conduction velocities were evaluated, and the bilateral anterior tibial muscles and extensor digitorum longus muscles were measured. The nerves were harvested and analyzed histologically. Motor conduction velocity was 37.4+/-4.1 m/s in the reversed group, and 36.6+/-5.5 m/s in the control group. The weight of the muscles was 7.2+/-0.8 g in the reversed orientation, and 7.0+/-1.0 g in the original orientation. None of the differences was statistically significant. Histologically, the axon counts and the axonal density distal to the nerve graft also showed no differences between groups. The sural nerves used did not have a major branch and their diameter was almost the same throughout its length. Reversing nerve graft polarity of a cable graft did not affect nerve regeneration electrophysiologically or histologically.