Effects of methanol on styrene metabolism among workers occupationally exposed at low concentrations

A survey was conducted in the second half of a work week on 39 male workers who were occupationally exposed to styrene in combination with methanol and methyl acetate during the production of plastic buttons. Time-weighted average exposure during an 8-h shift to styrene (Sty-A) and methyl acetate was monitored by carbon cloth-equipped personal samplers and to methanol by water-equipped ones. Urine samples were collected near the end of the shift and analyzed for mandelic (MA-U) and phenylglyoxylic acids (PhGA-U) by HPLC. Geometric mean styrene concentration was 12.4 ppm (g/g) with the maximum of 46 ppm, whereas the values for methanol and methyl acetate in combination were 23.5 ppm and 229 ppm, respectively. The relationship of MA-U and PhGA-U with Sty-A was examined by linear regression analysis. The equations for the regression lines were compared with the results from a previous survey (Ikeda et al. 1983) in which workers were exposed only to styrene, and the methods employed were identical with that in the present study. The comparison showed no evidence to suggest that styrene metabolism is suppressed by coexposure to methanol and methyl acetate at low concentrations below the current occupational exposure limit of 200 ppm.     

Primary malignant fibrous histiocytoma of the ascending colon: Report of a case

We report herein an unusual case of primary malignant fibrous histiocytoma (MFH) of the ascending colon. A 47-year-old man was admitted to our hospital for further investigations following the discovery of a mass in the right lower quadrant of the abdomen during a medical checkup. Abdominal ultrasonography (US) and computed tomography (CT) demonstrated a mass extending to the right lateral side from the ascending colon. At laparotomy, a tumor was found originating in the ascending colon and infiltrating the right lateral peritoneum. A right hemicolectomy and partial peritoneal dissection were performed followed by an ileotransverse colostomy reconstruction. The resected specimen contained a tumor measuring 7×5×4 cm, the cut surface of which was yellowish white, and the mucosa of the colon was intact. Based on histological and immunohistochemical inspection, the tumor was diagnosed as MFH of the ascending colon. We reviewed the total 18 known cases of colorectal MFH documented in the literature including our case. After surgery, 4 of 17 patients died of local recurrence, all within 42 months, indicating that early and complete excision of tumor is essential to achieve cure.     

A double bifurcated graft for abdominal aorta and bilateral iliac artery reconstruction

Revascularization of the hypogastric artery often tends to be neglected in aortoiliac reconstructive surgery; however, its incomplete revascularization can result in unfavorable complications such as buttock claudication or necrosis, vascular impotence, and colonic ischemia. Multiple vascular lesions in the abdominal aorta and bilateral iliac arteries were reconstructed using a newly designed double bifurcated graft in five male patients. All five patients demonstrated excellent graft limb patency and postoperative improvement of the ankle-brachial pressure index without any clinical signs of ischemia in regions of the hypogastric artery. Thus, we conclude that an aggressive approach toward hypogastric circulation maintenance is essential in aortoiliac reconstructive surgery. By using this double bifurcated graft, rapid and safe revascularization of the bilateral hypogastric arteries concomitant with the external iliac or femoral arteries can be performed.     

Peak oxygen uptake, ventilatory threshold and leg extension power in apparently healthy Japanese]

Peak oxygen uptake, ventilatory threshold (VT) and leg extension power were measured in 832 apparently healthy subjects (421 males, 411 females) aged 30-60 decades who performed medical examination at 4 health check up facilities. 1) Peak oxygen uptake was greater in male than female, and decreased with age in both sexes. Single regression formula on age were Y (ml/kg/min) = 46.6 - 0.36 x AGE, (r = 0.447, p < 0.001) in male and Y (ml/kg/min) = 35.3 - 0.23 x AGE, (r = 0.407, p < 0.001) in female. 2) VT was greater in male than female, and less decreased with age compared to maximal aerobic power. Single regression formula on age were Y (ml/kg/min) = 22.6 - 0.13 x AGE, (r = 0.371, p < 0.001) in male, Y (ml/kg/min) = 20.0 - 0.10 x AGE, (r = 0.301, p < 0.001) in female. 3) Leg extension power was greater in male than female, and decreased with age in both sexes. Single regression formula on age were Y (W/kg) = 31.9 - 0.27 x AGE, (r = 0.539, p < 0.001) in male and Y (W/kg) = 20.9 - 0.18 x AGE, (r = 0.510, p < 0.001) in female. Subjects in the present study showed height, weight and walk steps per day similar to those in National Nutrition Survey. Comparison of Peak oxygen uptake, ventilatory threshold and leg extensor power to previous studies revealed that these parameters were quite similar to the counterparts in the previous studies with less selection bias. It was suggested that subjects in this study were quite similar to normal Japanese population, and that Peak oxygen uptake, VT and leg extension power in the present study were of value for the evaluation of health related fitness in community and workplace.     

Studies on iodinated compounds. X. Isolation and purification of iodoglycyltyrosines]

The methods for the isolation and purification of iodoglycyltyrosines [glycyl-3-iodotyrosine (Gly-MIT) and glycyl-3,5-diiodotyrosine (Gly-DIT)] from a reaction mixture were examined by the use of high-performance liquid chromatography (HPLC). Glycyltyrosine (Gly-Tyr) was iodinated with iodine monochloride (ICl) (the molar ratio of Gly-Tyr to ICl was 1:1.5) in 0.1 M NaOH. The synthesized Gly-MIT and Gly-DIT were separated on a mu Bondapak C18 column employing stepwise gradient systems of a 0.1% trifluoroacetic acid/acetonitrile mixture and a water/acetonitrile mixture. Chemically pure Gly-MIT and Gly-DIT were obtained in 30.2% and 28.2% yields, respectively.     

Minimal synaptic delay in the saccadic output pathway of the superior colliculus studied in awake monkey

The synaptic organization of the saccade-related neuronal circuit between the superior colliculus (SC) and the brainstem saccade generator was examined in an awake monkey using a saccadic, midflight electrical-stimulation method. When microstimulation (50–100 A, single pulse) was applied to the SC during a saccade, a small, conjugate contraversive eye movement was evoked with latencies much shorter than those obtained by conventional stimulation. Our results may be explained by the tonic inhibition of premotor burst neurons (BNs) by omnipause neurons that ceases during saccades to allow BNs to burst. Thus, during saccades, signals originating from the SC can be transmitted to motoneurons and seen in the saccade trajectory. Based on this hypothesis, we estimated the number of synapses intervening between the SC and motoneurons by applying midflight stimulation to the SC, the BN area, and the abducens nucleus. Eye position signals were electronically differentiated to produce eye velocity to aid in detecting small changes. The mean latencies of the stimulus-evoked eye movements were: 7.9±1.0 ms (SD; ipsilateral eye) and 7.8±0.9 ms (SD; contralateral eye) for SC stimulation; 4.8±0.5 ms (SD; ipsilateral eye) and 5.1±0.7 ms (SD; contralateral eye) for BN stimulation; and 3.6±0.4 ms (SD; ipsilateral eye) and 5.2±0.8 ms (SD; contralateral eye) for abducens nucleus stimulation. The time difference between SC- and BN-evoked eye movements (about 3 ms) was consistent with a disynaptic connection from the SC to the premotor BNs.     

Nucleosides and nucleotides. 107. 2-(cycloalkylalkynyl)adenosines: adenosine A2 receptor agonists with potent antihypertensive effects.

Adenosine receptor-binding profiles in rat brain tissues and antihypertensive effects in spontaneously hypertensive rats (SHR) of a series of 2-(cycloalkylalkynyl)adenosines (2-CAAs) and their congeners are described. The structure-activity relationship of this series of compounds is discussed, focusing on the length of the alkynyl side chain and bulkiness of the terminal cycloalkyl substituents in terms of binding activity and cardiovascular effects. All the 2-CAAs had a preferential affinity for A2 receptors. Of these derivatives, 2-(3-cyclopentyl-1-propyn-1-yl)adenosine (10b) exhibited the most selective affinity for A2 receptors (Ki ratio: A1/A2 = 70) on the basis of receptor binding. In the C-2 binding region of adenosine, compounds often have potent and/or selective A2 activity from introduction of an acetylenic group at the C-2 position followed by one methylene residue further followed by a hydrophobic substituent such as a cycloalkyl ring at the terminal position of the alkynyl side chain. Intravenous injection of 10b up to 100 micrograms/kg had a potent hypotensive effect without a marked decrease in heart rate in anesthetized SHR. Compounds 10j-s, with a hydroxyl group in the C-3" position of the alkynyl side chain, had a potent affinity for both A1 and A2 receptors, but they were not highly selective for A2 receptors. These compounds caused a marked bradycardia upon intravenous administration in anesthetized SHR. Oral administration of 10b (0.1-1 mg/kg) had a potent and long-lasting antihypertensive effect in conscious SHR.     

Micro-mainframe-link Personal Clinical Research System

We constructed a micro-mainframe-link clinical research system for personal use (Personal Clinical Research System). This system was developed with both a mainframe computer and a personal computer (PC). The prepared programs included a database manager (on the mainframe computer), a user interface program (on the PC), and a communication control program that connected the mainframe computer with the PC. The database on the mainframe computer was constructed by two methods. The first method was to transmit data from the PC to the mainframe computer. The second method was to extract data from the patient information database. Using this system, a physician is able to construct a personal research database that contains interesting data for the physician. In addition, the physician is able to accumulate data on a special field using this system. A discharge summary system is now in operation as an example of this system.     

Ostreopsis sp., a possible origin of palytoxin (PTX) in parrotfish Scarus ovifrons.

A clone of toxic dinoflagellate Ostreopsis sp. and six specimens of a parrotfish Scarus ovifrons were collected in October 1997 at Tokushima Prefecture, Japan. Ostreopsis sp. was cultured in ESM medium for 16 days, and after rearing the cell pellet (about 4.0x10(5) cells) was extracted with 50% methanol, partitioned between an aqueous layer and 1-butanol layer, and biochemically tested. Similarly, the crude toxin from S. ovifrons was extracted, and tested. The mice injected with each 1-butanol layer from Ostreopsis sp. and S. ovifrons showed the common symptoms of convulsion, drowsiness and collapse, and died within 48 h. The lethal potency of Ostreopsis sp. was calculated to be 1.0x10(-4) MU/cell. All specimens of S. ovifrons were found to be toxic, where the highest potency was determined as 2 MU/g in muscle of one specimen. After being injected with toxins, the serum creatine phosphokinase levels of mice were found to be elevated. Toxins from Ostreopsis sp. and S. ovifrons showed delayed haemolytic activity with mouse and human erythrocytes, which was inhibited by an anti-palytoxin (PTX) antibody antibody and ouabain. Toxins from Ostreopsis sp. and S. ovifrons thus resembled each other, and strongly suggested to be PTX or its akin substance. Additionally, a considerable number of adherent Ostreopsis sp. was found in the gut contents of S. ovifrons during the heavy occurrence of Ostreopsis sp. in October 1997 at Tokushima Prefecture. From the above results, it can be strongly postulated that the dinoflagellate Ostreopsis sp. is the origin of PTX which is sequestered by the parrotfish S. ovifrons through food chain.     

Suppressive effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the high-affinity antibody response in C57BL/6 mice.

In the humoral immune response to an invasion of foreign antigens, B cells differentiate into low-affinity antibody-forming cells (AFCs) that mainly secrete IgM or, through germinal center (GC) formation, into high-affinity AFCs that secrete IgG-class antibodies with a higher affinity for the antigen. Previous studies have established the suppressive effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on low-affinity antibody responses to antigens. However, whether and how TCDD affects the high-affinity antibody response to antigens has not yet been clarified. In this paper we investigate the effects of TCDD on GC formation, high-affinity AFC generation, and high-affinity antibody production in the primary humoral immune response. C57BL/6 mice were orally administered 0 or 20 microg/kg of TCDD and subsequently immunized with alum-precipitated ovalbumin (OVA) on day 0. Then the GC formation in the spleen and OVA-specific antibodies in the plasma, was evaluated until day 14 postimmunization. TCDD exposure reduced the production of OVA-specific IgG1 on days 10 and 14. GC formation in the spleen was also suppressed by TCDD exposure, and the suppression persisted from day 7 until day 14. In TCDD-administered mice, on day 7, cellular proliferation in the GCs was significantly suppressed, although apoptosis was not markedly affected. In order to measure high-affinity antibody and high-affinity AFCs, the mice were administered TCDD followed by immunization with alum-precipitated (4-hydroxy-3-nitrophenyl) acetyl linked to chicken gamma-globulin (NP-CG). The frequency of high-affinity NP-specific AFCs that bind to low-haptenated antigen was clearly shown to be reduced in the spleen on days 10 and 14. Furthermore, the high-affinity anti-NP IgG1 levels on days 10 and 14 postimmunization were significantly reduced by TCDD exposure. Taken together, the results of this paper demonstrate that TCDD exposure inhibits the generation of high-affinity AFCs and high-affinity antibody production during the primary humoral immune response and suggest that these alterations were caused by the suppression of antigen-responding B-cell proliferation induced by TCDD during GC formation.