Nondestructive evaluation of blood flow in a dialyzer using X-ray computed tomography

It is very important to observe the concentrations and flow patterns of blood through a dialyzer to evaluate its function and to obtain the most appropriate design. We established a visualization method for the blood flow pattern in a dialyzer using X-ray computed tomography, and investigated the so-called internal filtration phenomenon. The results obtained were as follows: (1) The influence of 5% BaSO₄, which was added to the blood as a contrast medium, on the filtration rate of the dialyzer was minimal. (2) The relationship between the concentration of BaSO₄ and the Hounsfield unit value was expressed by linear regression. (3) Hounsfield unit values increased massively just after blood entered the dialyzer and peak values increased with dialysate perfusion under the following conditions: the dialyzer (BS-1.6UL, polysulfone hollow fibers) was used, and bovine blood with 5% BaSO₄ added was used at a blood flow rate of 200ml/min. The dialysate flow rate was 500ml/min and the slice thickness of X-ray computed tomography was 1–10mm. (4) It was observed that blood flowed slightly faster in the center than the peripheral portion of the dialyzer, when the flow pattern was followed after pulse injection of blood containing 20% BaSO₄ into the dialyzer. It was concluded that this method could possibly be utilized not only qualitatively but also quantitatively for observation of the real state of blood flow and in designing dialyzers.     

Production and release of infectious hepatitis C virus from human liver cell cultures in the three-dimensional radial-flow bioreactor

Lack of efficient culture systems for hepatitis C virus (HCV) has been a major obstacle in HCV research. Human liver cells grown in a three-dimensional radial-flow bioreactor were successfully infected following inoculation with plasma from an HCV carrier. Subsequent detection of increased HCV RNA suggested viral replication. Furthermore, transfection of HCV RNA transcribed from full-length cDNA also resulted in the production and release of HCV virions into supernatant. Infectivity was shown by successful secondary passage to a new culture. Introduction of mutations in RNA helicase and polymerase regions of HCV cDNA abolished virus replication, indicating that reverse genetics of this system is possible. The ability to replicate and detect the extracellular release of HCV might provide clues with regard to the persistent nature of HCV infection. It will also accelerate research into the pathogenicity of HCV, as well as the development of prophylactic agents and new therapy.     

Further Survey of Aflatoxin M1 in Milk Powders by ELISA

A survey of AFM₁ residues in 58 commercial milk powder samples was carried out using an enzyme‐linked immunosorbent assay (ELISA) based on a monoclonal antibody against aflatoxin M₁ (AFM₁). The samples were collected from the USA (10), China (28), Italy (14), New Zealand (3) and Poland (3). The ELISA was performed without the need for clean‐up procedures. The data revealed that 4 (US), 21 (Chinese) and 1 (Polish) samples were positive for AFM₁, with an average of 95.5, 102.8 and 85.0 pg g^‐1 of the AFM₁respectively.     

The three-dimensional microvascular arrangement around rat dorsal hairs as revealed by scanning electron microscopy

The three-dimensional microvascular arrangement around the dorsal hairs in vascular corrosion casts of adult Wistar rats was studied by scanning electron microscopy. Each anagen dorsal hair was surrounded by a basket-like capillary network, which was supplied by the branches of the subcutaneous artery and drained into the veins continuous with the subcutaneous vein. The capillary network surrounding the anagen dorsal hair was denser at its lower part, and became more sparse at its upper part. Transmission electron microscopy showed that the capillaries around the hair bulb possessed fenestrations. Our findings indicate that the microvascular arrangement around the anagen dorsal hair is so organized as to supply the hair bulb, which is the most important area for hair growth, with abundant blood. This study was presented at the 24th Annual Meeting of the Clinical Electron Microscopy Society of Japan, Okayama, September 17–19, 1992.     

Proposed criteria for mixed-dust pneumoconiosis: definition, descriptions, and guidelines for pathologic diagnosis and clinical correlation

We defined mixed-dust pneumoconiosis (MDP) pathologically as a pneumoconiosis showing dust macules or mixed-dust fibrotic nodules (MDF), with or without silicotic nodules (SN), in an individual with a history of exposure to mixed dust. We defined the latter arbitrarily as a mixture of crystalline silica and nonfibrous silicates. According to our definition of MDP, therefore, MDF should outnumber SN in the lung to make a pathologic diagnosis of MDP. In the absence of confirmation of exposure, mineralogic analyses can be used to support the pathologic diagnosis. The clinical diagnosis of MDP requires the exclusion of other well-defined pneumoconioses, including asbestosis, coal workers’ pneumoconiosis, silicosis, hematite miners’ pneumoconiosis, welders’ pneumoconiosis, berylliosis, hard metal disease, silicate pneumoconiosis, diatomaceous earth pneumoconiosis, carborundum pneumoconiosis, and corundum pneumoconiosis. Typical occupations associated with the diagnosis of MDP include metal miners, quarry workers, foundry workers, pottery and ceramics workers, and stonemasons. Irregular opacities are the major radiographic findings in MDP (ILO 1980), in contrast to silicosis, in which small rounded opacities predominate. Clinical symptoms of MDP are nonspecific. MDP must be distinguished from a variety of nonoccupational interstitial pulmonary disorders.     

Neurotoxicity of Clostridium perfringens Epsilon-Toxin for the Rat Hippocampus via the Glutamatergic System

The neurotoxicity of epsilon-toxin, one of the major lethal toxins produced by Clostridium perfringens type B, was studied by histological examination of the rat brain. When the toxin was injected intravenously at a lethal dose (100 ng/kg), neuronal damage was observed in many areas of the brain. Injection of the toxin at a sublethal dose (50 ng/kg) caused neuronal damage predominantly in the hippocampus: pyramidal cells in the hippocampus showed marked shrinkage and karyopyknosis, or so-called dark cells. The dark cells lost the immunoreactivity to microtubule-associated protein-2, a postsynaptic somal and dendric marker, while acetylcholinesterase-positive fibers were not affected. Timm’s zinc staining revealed that zinc ions were depleted in the mossy layers of the CA3 subfield containing glutamate as a synaptic transmitter. The cerebral blood flow in the hippocampus was not altered significantly before or after administration of the toxin, as measured by laser-Doppler flowmetry, excluding the possibility that the observed histological change was due to a secondary effect of ischemia in the hippocampus. Prior injection of either a glutamate release inhibitor or a glutamate receptor antagonist protected the hippocampus from the neuronal damage caused by epsilon-toxin. These results suggest that epsilon-toxin acts on the glutamatergic system and evokes excessive release of glutamate, leading to neuronal damage.     

Camostat mesilate attenuates pancreatic fibrosis via inhibition of monocytes and pancreatic stellate cells activity

Camostat mesilate (CM), an oral protease inhibitor, has been used clinically for the treatment of chronic pancreatitis in Japan. However, the mechanism by which it operates has not been fully understood. Our aim was to evaluate the therapeutic efficacy of CM in the experimental pancreatic fibrosis model induced by dibutyltin dichloride (DBTC), and we also determined the effect of CM on isolated monocytes and panceatic stellate cells (PSCs). In vivo, chronic pancreatitis was induced in male Lewis rats by single administration of 7 mg/kg DBTC and a special diet containing 1 mg/g CM was fed to the DBTC+CM-treated group from day 7, while the DBTC-treated group rats were fed a standard diet. At days 0, 7, 14 and 28, the severity of pancreatitis and fibrosis was examined histologically and enzymologically in both groups. In vitro, monocytes were isolated from the spleen of a Lewis rat, and activated with lipopolysaccharide stimulation. Thereafter, the effect of CM on monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-alpha (TNF-alpha) production from monocytes was examined. Subsequently, cultured rat PSCs were exposed to CM and tested to see whether their proliferation, MCP-1 production and procollagen alpha1 messenger RNA expression was influenced by CM. In vivo, the oral administration of CM inhibited inflammation, cytokines expression and fibrosis in the pancreas. The in vitro study revealed that CM inhibited both MCP-1 and TNF-alpha production from monocytes, and proliferation and MCP-1 production from PSCs. However, procollagen alpha1 expression in PSCs was not influenced by CM. These results suggest that CM attenuated DBTC-induced rat pancreatic fibrosis via inhibition of monocytes and PSCs activity.     

Origins and pathways of fluid entering sublobular lymphatic vessels in cat livers

The liver, which produces a large volume of lymph, has a lymphatic system which can be classified into three categories: portal, sublobular, and superficial lymphatic vessels. As little is known about the origin and pathways of sublobular lymph, this study demonstrates pathways of interstitial fluid flowing into sublobular lymphatic vessels. Livers from cats whose thoracic ducts were either ligated or non-ligated were examined by light-, transmission electron- and scanning electron-microscopy (SEM). Complete ligation of the thoracic duct caused significant dilation of the hepatic sinusoids, the space of Disse, and channels passing through the limiting plate. Sublobular interstitial space and sublobular lymphatic vessels were also expanded. The channels between hepatocytes forming the limiting plate contained collagen fibers, and connected the space of Disse with a sublobular interstitial space. The alkali-water maceration/SEM confirmed that collagen fibers traversing the layer of the limiting plate independently of blood vessels connected collagen fibers in the space of Disse with those in the sublobular space. Complete ligation of the thoracic duct also showed an accumulation of mast cells and plasma cells in the sublobular interstitial space. Our data suggest that fluid in the space of Disse flows along collagen fibers in channels traversing the limiting plate as well as those along the sinusoids and central veins that drain into sublobular veins, and enters the sublobular interstitial space to finally lead into sublobular lymphatic vessels. Our study has also shown that hepatic lymphostasis causes the accumulation of mast cells and plasma cells in the sublobular interstitial space, which may be involved in lymphangiogenesis and fibrogenesis.     

Clinical heterogeneity of neonatal intrahepatic cholestasis caused by citrin deficiency: case reports from 16 patients

A deficiency of citrin, which is encoded by the SLC25A13 gene, causes both adult-onset type II citrullinemia (CTLN2) and neonatal intrahepatic cholestasis (NICCD). We analyzed 16 patients with NICCD to clarify the clinical features of the disease. Severe intrahepatic cholestasis with fatty liver was the most common symptom, but the accompanying clinical features were variable, namely; suspected cases of neonatal hepatitis or biliary atresia, positive results from newborn screening, tyrosinemia, failure to thrive, hemolytic anemia, bleeding tendencies and ketotic hypoglycemia. Laboratory data showed elevated serum bile acid levels, hypoproteinemia, low levels of vitamin K-dependent coagulation factors, and hypergalactosemia. Hypercitrullinemia was detected in 11 out of 15 patients examined. Most of the patients were given a lactose-free and/or medium chain triglycerides-enriched formula and lipid-soluble vitamins. The prognosis of the 16 patients is going fairy well at present, but we should observe these patients carefully to see if they manifest any symptom of CTLN2 in the future.