Mammalian Cry1 and Cry2 are essential for maintenance of circadian rhythms

Many biochemical, physiological and behavioural processes show circadian rhythms which are generated by an internal time-keeping mechanism referred to as the biological clock. According to rapidly developing models, the core oscillator driving this clock is composed of an autoregulatory transcription-(post) translation-based feedback loop involving a set of 'dock' genes. Molecular clocks do not oscillate with an exact 24-hour rhythmicity but are entrained to solar day/night rhythms by light. The mammalian proteins Cryl and Cry2, which are members of the family of plant blue-light receptors (cryptochromes) and photolyases, have been proposed as candidate light receptors for photoentrainment of the biological clock. Here we show that mice lacking the Cryl or Cry2 protein display accelerated and delayed free-running periodicity of locomotor activity, respectively. Strikingly, in the absence of both proteins, an instantaneous and complete loss of free-running rhythmicity is observed. This suggests that, in addition to a possible photoreceptor and antagonistic clock-adjusting function, both proteins are essential for the maintenance of circadian rhythmicity.

[Adhesive and sealing effects of TO-193 on tissues and organs in various experimental models]

We studied the adhesive and sealing effects of sheet style fibrin adhesive, TO-193 (TachoComb), on some tissues and organs, comparing them with those of sheet style collagen agent, collagen sponge, Novacol, and Avitene and liquid fibrin adhesive agent, Beriplast P. TO-193 showed more a potent adhesive effect on liver than the sheet style collagen agents and was more potent on bone and skin than the liquid fibrin adhesive agent. Furthermore, TO-193 had a potent sealing effect at the site of incomplete suture immediately after application on a motile organ such as lung and stomach. These effects may be partly attributable to rapid expression of the effect due to the presence of a high concentration of fibrinogen on coverage. Enhancement of fibrin penetrability to the tissues by compression and inhibition of cleavage of coverage by the collagen sponge also may be participating in the effects of TO-193. These results suggest that TO-193 will be a valuable adhesive and sealing agent.

A putative blue-light receptor from Drosophila melanogaster

A gene encoding a 62.5 kDa homolog of Drosophila melanogaster photolyase was isolated. Purified recombinant protein contained a flavin adenine dinucleotide chromophore. The recombinant protein did not show photolyase activity for either cyclobutane pyrimidine dimers or 6-4 photoproducts in vitro as well as in vivo in Escherichia coli host cells, suggesting that the protein is not a DNA repair enzyme but a blue-light photoreceptor. Reverse transcription polymerase chain reaction analysis showed that the gene is more expressed in head than in body and that it is more expressed in antennae than in legs, wings and mouth appendages. In a phylogenetic tree of the photolyase family, the Drosophila photolyase homolog is located in a cluster containing 6-4 photolyases and mammalian photolyase homologs, which is only distantly related to the clade of higher plant blue-light photoreceptors. The mammalian photolyase homologs are more closely related to Drosophila 6-4 photolyase than to the Drosophila photolyase homolog, suggesting different roles of the photolyase homologs.

Characterization of photolyase/blue-light receptor homologs in mouse and human cells

We isolated and characterized mouse photolyase-like genes, mCRY1 (mPHLL1) and mCRY2 (mPHLL2), which belong to the photolyase family including plant blue-light receptors. The mCRY1 and mCRY2 genes are located on chromosome 10C and 2E, respectively, and are expressed in all mouse organs examined. We raised antibodies specific against each gene product using its C-terminal sequence, which differs completely between the genes. Immunofluorescent staining of cultured mouse cells revealed that mCRY1 is localized in mitochondria whereas mCRY2 was found mainly in the nucleus. The subcellular distribution of CRY proteins was confirmed by immunoblot analysis of fractionated mouse liver cell extracts. Using green fluorescent protein fused peptides we showed that the C-terminal region of the mouse CRY2 protein contains a unique nuclear localization signal, which is absent in the CRY1 protein. The N-terminal region of CRY1 was shown to contain the mitochondrial transport signal. Recombinant as well as native CRY1 proteins from mouse and human cells showed a tight binding activity to DNA Sepharose, while CRY2 protein did not bind to DNA Sepharose at all under the same condition as CRY1. The different cellular localization and DNA binding properties of the mammalian photolyase homologs suggest that despite the similarity in the sequence the two proteins have distinct function(s).

Potentiation of acetaminophen hepatotoxicity and mortality by doxapram in mice

Whether a single dose of doxapram (DOP) can modulate the acute toxicity and the hepatotoxicity induced by acetaminophen (AA) was examined. Pretreatment with DOP (40 mg/kg, i.p.) 30 min prior to the administration of AA dose-dependently potentiated the lethality of AA in both native mice and mice fasted for 18 h, and the potentiating activity was greater in fasted mice than in native mice. The hepatotoxicity of AA was assessed by plasma transaminases activity (glutamyl oxaloacetic transaminase, GOT; glutamyl pyruvic transaminase, GPT) and the amount of plasma lipid peroxides at 6, 12, 18, 24, 36 and 48h after the administration of AA and histopathological examination of liver sections at 24 h after the administration of AA. DOP (40 mg/kg, i.p.) did not increase the plasma transaminase activity or the lipid peroxides level significantly, whereas AA administration to DOP-treated animals produced earlier maximal elevation of transaminase and lipid peroxide values compared to AA alone. These findings indicate that mortality and hepatotoxicity of AA is potentiated by DOP in mice.

Thalidomide promotes the release of tumor necrosis factor-alpha (TNF-alpha) and lethality by lipopolysaccharide in mice

We investigated the in vivo effects of thalidomide on the production of tumor necrosis factor-alpha (TNF-alpha). An in vivo systemic release of TNF-alpha occurred after the injection of lipopolysaccharide (LPS) in male ddY mice, and the TNF-alpha serum levels reached 652.2 +/- 75.7 pg/ml 90 min after the injection of LPS (0.3 mg/kg, i. p.). When thalidomide (1, 3, or 6 mg/kg) was administered intraperitoneally 3 h before the injection of LPS (0.3 mg/kg, i. p.), thalidomide markedly enhanced LPS-induced TNF-alpha release in a dose-dependent manner. The TNF-alpha serum levels at 90 min were 640 +/- 58.6, 1985 +/- 132.6, and 2795 +/- 203.5 pg/ml, respectively, compared to 628.6 +/- 64.4 pg/ml in mice treated with LPS-alone. Pretreatment with a single injection of thalidomide (1, 3, or 6 mg/kg, i. p.) dose-dependently increased the subsequent mortality caused by a challenge with LPS (15 mg/kg, i. p.), a dose that caused death in 10% of the control mice. We conclude that thalidomide enhances in vivo TNF-alpha secretion and the lethality of LPS in mice.

Assessment of the expression of p53, MIB-1 (Ki-67 antigen), and argyrophilic nucleolar organizer regions in carcinoma of the extrahepatic bile duct

BACKGROUND

The authors retrospectively examined the predictive value of p53, MIB-1, and the argyrophilic nucleolar organizer regions (AgNOR) and examined the relationships among them in carcinoma of the extrahepatic bile duct (EHBD).

METHODS

Formalin fixed, paraffin embedded specimens from 54 patients with EHBD carcinoma were immunostained with MIB-1 against the Ki-67 nuclear antigen and p53 by the avidin-biotin peroxidase complex method, using the antigen retrieval technique of heating tissue sections in a microwave oven. The AgNOR proteins were localized at the optical level, as shown by a one-step silver staining technique.

RESULTS

MIB-1 and AgNOR were closely associated with lymph node metastasis (P < 0.01). The cumulative survival rate for patients with a low MIB-1 labeling index (LI) (< 29%) was significantly better than that for patients with a high MIB-1 LI (> or = 29%) in cases of EHBD carcinoma (P < 0.05), but MIB-1 was not an independent prognostic factor in multivariate analysis. The results indicated that AgNOR and p53 overexpression had no prognostic value. The authors detected p53 in 24 of the 54 EHBD carcinomas (44.4%). There was a significant correlation between MIB-1 and AgNOR (P < 0.01). The authors found that neither MIB-1 nor AgNOR correlated with p53 overexpression.

CONCLUSIONS

MIB-1 and AgNOR proved to be useful predictors of lymph node metastasis. The results of this study indicated that MIB-1 and AgNOR might be markers of the progression of EHBD carcinoma.

Immunohistochemical detection of proliferating cell nuclear antigen and p53 expression in carcinoma of the extrahepatic bile duct

We used an immunohistochemical method to determine the concentrations of p53 and proliferating cell nuclear antigen (PCNA) to evaluate their usefulness as a predictor of malignancy and examined the relationship between PCNA and p53 in carcinomas of the extrahepatic bile duct (EHBD). Paraffin-embedded specimens from 46 patients were immunostained for PCNA and p53 using PC10 and DO7 monoclonal antibodies, respectively. The PCNA labeling index (LI) was closely associated with the stages of the tumor and depth of invasion (p < 0.05). The cumulative survival rate of patients with a low PCNA LI (LI < 47%) was found to be significantly better than that of patients with a high PCNA LI (LI > or = 47%) in all cases and patients with advanced cancer by univariate analysis (p < 0.05), but PCNA LI was not an independent prognostic factor in multivariate analysis. We detected p53 in 37% of the EHBD cancers. We also found that p53 positivity was not related to the percentage of PCNA-labelled cells or survival. The results suggest that PCNA immunoreactivity may be a useful predictor of malignancy in patients with EHBD carcinomas.

[Open heart surgery without homologous blood transfusion in elderly patients]

Preoperative autologous blood donation has been widely accepted to perform surgery in orthopedics, gynecology and cardiac surgery. In elderly patients, however, it has been supposed that most of these patients have anemic tendency before predonation as well as poor response to erythropoietic stimuli, so that preoperative blood deposit is limited to apply them. In order to reduce homologous blood transfusion in open-heart surgery, preoperative blood deposit, combined with erythropoietin administration and intraoperative blood salvage, have been routinely used even for the elderly patients in our hospital since 1989. In present study, we verified above concepts and obtained the results that demonstrated little differences in the blood reproducing ability, the rate of predonation, and the recovery after the operation, between the elderly and the younger. We concluded that autologous blood transfusion combining preoperative deposit with intraoperative blood salvage was the efficient and safe method even in the elderly patients.

Analysis of wool fiber by alkali-catalyzed pyrolysis gas chromatography

Alkali-catalyzed pyrolysis gas chromatography (PyGC) has been used to identify minute samples of wool fiber. The wool sample to which aqueous sodium hydroxide was added was pyrolyzed in a Curie-point pyrolyzer attached to a gas chromatograph or a gas chromatograph-mass spectrometer. The addition of an aqueous solution of sodium hydroxide increased the production of specific volatile pyrolysis products from the constitutive amino acid residues of wool protein, i.e. acetaldehyde from alanine or proline, isobutyronitrile from valine, 2-methylbutyronitrile from isoleucine, isovaleronitrile from leucine and toluene from phenylalanine. Compared with conventional non-catalyzed PyGC, the alkali-catalyzed PyGC was found to greatly improve the detection limit of wool fiber and make it possible to analyze very minute samples. The alkali-catalyzed PyGC presented here has been shown to be applicable to minute thermally-denatured samples of wool fiber which cannot be identified successfully by morphological inspection using a microscope or by using Fourier-transform infrared microspectroscopy. Furthermore, the present PyGC method was successfully used for several protein samples and was shown to be useful for analysis of proteins other than wool fibers by using different special pyrograms reflecting different amino acid compositions.

Determination of N-(trans-4-isopropylcyclohexanecarbonyl)-D-phenylalanine and its metabolites in human plasma and urine by column-switching high-performance liquid chromatography with ultraviolet detection

A simple, rapid and sensitive two column-switching high-performance liquid chromatographic (HPLC) method with ultraviolet detection at 210 nm has been developed for the determination of N-(trans-4-isopropylcyclohexanecarbonyl)-D-phenylalanine (AY4166, I) and its seven metabolites in human plasma and urine. Measurements of I and its metabolites were carried out by two column-switching HPLC, because metabolites were classified into two groups according to their retention times. After purification of plasma samples using solid-phase extraction and direct dilution of urinary samples, I and each metabolite were injected into HPLC. The calibration graphs for plasma and urinary samples were linear in the ranges 0.1 to 10 microg ml(-1) and 0.5 to 50 microg ml(-1), respectively. Recoveries of I and its seven metabolites were over 88% by the standard addition method and the relative standard deviations of I and its metabolites were 1-6%.

Small intestinal absorption during endotoxemia in swine

We studied the effects of systemic endotoxemia on small intestinal absorption in an in vivo animal model. Seven adolescent Yorkshire swine underwent creation of 25 cm distal ileal Thiry-Vella fistulae. After 1 week recovery, the fistulae were perfused with a solution of glucose and electrolytes labeled with 14C-PEG, and net absorption of water, Na+, Cl-, and glucose was calculated. Animals were studied under three different conditions: (1) Basal fasting state, (2) immediately after intravenous injection of E. coli lipopolysaccharide (LPS; 250 micrograms/kg), and (3) 24 hours after LPS. Water, Na+, and Cl- absorption was significantly reduced 2 hours after LPS, but recovered to baseline values by the third hour after LPS. Twenty-four hours after LPS water, Na+, and Cl- absorption was significantly decreased below baseline values. Glucose absorption after LPS paralleled that of water and electrolytes, except that the transient early recovery was not observed. Histological studies of the ileum after LPS showed marked epithelial inflammation at 6 hours, villous atrophy at 24 hours, and signs of recovery at 7 days. Intestinal absorption of water, electrolytes, and glucose is adversely affected in the immediate and early periods after an endotoxemic episode, but the histological epithelial injury secondary to endotoxemia is reversible.

Determination of N-(trans-4-isopropylcyclohexylcarbonyl)-D-phenylalanine in human plasma by solid-phase extraction and column-switching high-performance liquid chromatography with ultraviolet detection

A column-switching high-performance liquid chromatography method with ultraviolet detection at 210 nm has been developed for the determination of N-(trans-4-isopropylcyclohexylcarbonyl)-D-phenylalanine (AY4166, I) in human plasma. Plasma samples were prepared by solid-phase extraction with Sep-Pak Light tC18, followed by HPLC. The calibration graph for I was linear in the range 0.1-20 micrograms/ml. The limit of quantitation of I, in plasma, was 0.05 microgram/ml. The recovery of spiked I (0.5 microgram/ml) to drug-free plasma was over 92% and the relative standard deviation of spiked I (0.5 microgram/ml) compared to drug-free plasma was 4.3% (n = 8).

Sustained pulmonary vasodilation after inhaled nitric oxide for hypoxic pulmonary hypertension in swine

It has been shown that pulmonary vasodilation is sustained after discontinuation of inhaled nitric oxide (INO) during moderate hypoxic pulmonary hypertension (HPH) in swine. The present investigations demonstrated how INO dose, hypoxia duration, and endogenous NO production influence this important phenomenon. Fifteen adolescent Yorkshire swine were randomly assigned to three groups (n = 5 each) and underwent the following phasic experimental protocol: (I) Baseline ventilation (FIO2 = .3); (II) Initiating HPH (FIO2 = .16 to .18, PaO2 = 45 to 55 mm Hg); (III) INO at 10 ppm; (IV) Posttreatment observation; (V) INO of 80 ppm; and (VI) Posttreatment observation. Phase II (pretreatment hypoxia) lasted 30 minutes in group A (short hypoxia) and 120 minutes in group B (long hypoxia). N-nitro-L-arginine methyl ester (NAME) was used to inhibit nitric oxide synthase (NOS) throughout the experiment in group C (short hypoxia + NAME). Hemodynamics and blood gases were monitored by systemic and pulmonary artery catheters placed by femoral cutdown. Analysis of variance with post-hoc adjustment was used to compare groups at each phase, and the paired t test was used for comparisons within a group. With respect to baseline mean pulmonary artery pressure (MPAP) and pulmonary vascular resistance (PVR), there were no significant differences among the three groups. MPAP and PVR were significantly higher in group C than in group A during phase II, (MPAP, 76% +/- 8% v 33% +/- 2%; PVR, 197% +/- 19% v 78% +/- 10%; P < .05). There were no significant differences in MPAP or PVR during phases III through VI. When MPAP was expressed as percent dilation, 80 ppm caused significantly more dilation than did 10 ppm in all three groups. Groups A and C had significantly higher sustained pulmonary artery dilation after 80 ppm than after 10 ppm (A, 82% +/- 31% v 17% +/- 11%; C, 68% +/- 10% v 42% +/- 12%; both P < .05), but group B did not (43% +/- 15% v 30% +/- 9%; P = .25). High dose results in stronger vasodilation than low dose during and after INO for moderate HPH of short duration. Long hypoxia blunts this high-dose advantage. Endogenous NO inhibition augments HPH but does not decrease pulmonary vasodilation during or after INO.

Water transport in native and transplanted porcine jejunum

Adequate absorptive function of transplanted small intestine is essential for success of this procedure. This study compared water transport under basal and meal stimulated conditions in the transplanted swine jejunum to native jejunum. Six female adolescent Yorkshire swine were randomized to undergo construction of either a 25-cm native proximal jejunal Thiry-Vella Fistula (TVF), n=3, or a 25-cm proximal jejunal allograft TVF, n=3. Immunosuppression in the transplanted animals was accomplished with intravenous methylprednisolone, azathioprine, and cyclosporin. Jejunal absorption studies, each 4 hr long, were performed utilizing 14C-polyethylene glycol to calculate net water flux. Each animal underwent at least three fasting and three postprandial studies. New water flux was negative, i.e., secretory, in both the native and transplanted proximal swine jejunum. In the basal state, integrated hourly water transport was more secretory in the native bowel vs the transplanted bowel during the 2nd, 3rd, and 4th experimental hr (-4.6 +/- .8 vs -2.1 +/- .7 cc, P = 0.034; -4.4 +/- .7 vs -1.8 +/- .6 cc, P = 0.012; and -4.7 vs 1.3 +/- .5 cc, P < 0.005), respectively. In native jejunum, integrated hourly water transport was less secretory 2 and 3 hr postprandially compared to basal (-1.9 +/- .5 vs -4.4 +/- .7 cc, P = 0.016; and -2.0 +/- .5 vs -4.7 +/- .7 cc, P = 0.021), respectively. This postprandial proabsorptive response did not occur in the transplanted jejunum. Native and transplanted jejunal water flux in the postprandial state did not differ significantly. We conclude that there is higher secretion in native vs transplanted jejunum during fasting. The postprandial proabsorptive response of the proximal porcine jejunum is abolished by transplantation.

[Gas chromatographic analysis of reduction products of paraquat, diquat and the related compounds: reductive cleavage in the pyridine ring on N-alkylpyridinium derivatives with NaBH4-NiCl2 reduction system, and inhibition of the cleavage]

When N-alkylpyridinium derivatives were reduced with sodium borohydride-nickel (II) chloride reduction system, reductive cleavage occurred at the C-N bond in the pyridine ring of N-alkylpyridinium derivatives to give a small amount of reductive cleavage product along with the major perhydrogenated product. It was presumed in the previous report that this reductive cleavage in the pyridine ring proceeded through a complex of nickel ion and 1,2,3,6-tetrahydropyridine derivatives produced with NaBH4 alone reduction. The abundances of these reductive cleavage products arising from N-alkylpyridinium derivatives, i.e., paraquat, diquat and so on, are capable of giving a bad effect on the accuracy of gas chromatographic analysis. For the purpose of inhibition of the reductive cleavage in this reduction system, a suitable catalyst was examined. In addition, we pursued whether borane-1,2,3,6-tetrahydropyridine derivative complexes arose from N-alkylpyridinium derivatives by NaBH4 alone reduction or not, and whether these borane-amine complexes were the precursors of reductive cleavage products or not. N-Alkyl-1,2,3,6-tetrahydropyridine derivatives (III-I, IV-I, VI-I, VII-I and VIII-I) and the corresponding borane-amine complexes (III-II, IV-II, VI-II, VII-II and VIII-II) were synthesized by NaBH4 reduction in aqueous solution of N-alkylpyridinium salts, i.e. I, II, 1,4-dimethylpyridinium iodide (III), 1-dodecylpyridinium chloride (IV), 1,1'-diethyl-4,4'-dipyridinium dichloride (V), 1-methyl-4-phenylpyridinium iodide (VI), 1-n-propylpyridinium iodide (VII) and 1-n-butylpyridinium iodide (VIII). The structure of the borane-amine complexes were proved by the Mass spectrometry and 1H- and 13C-NMR analysis. The NiCl2-NaBH4 reduction of the borane-amine complexes gave the perhydrogenated products alone, but not reductive cleavage products. In conclusion, it was recognized that the precursors of reductive cleavage products were not borane-amine complexes, but 1,2,3,6-tetrahydropyridine. Furthermore, it was found the reductive cleavage at the C-N bond in the pyridine ring of these 1,2,3,6-tetrahydropyridine derivatives was hindered by applying Amberlite-Ni2B, NaBH4 reduction system.

Severity of hypoxia predicts response to nitric oxide in a porcine pulmonary hypertension model

Although inhaled nitric oxide (NO) has been variably successful in resolving pulmonary hypertension in neonates, children, and adults, no parameters predictive of response to this therapy have been elucidated. We conducted an animal study to determine if severity of hypoxia can predict magnitude and sustenance of response to inhaled NO therapy. Seven Yorkshire swine weighing 11 to 20 kg underwent 16 experiments, each consisting of four phases: Phase 1: Control period of ventilation on FIO2 .3; phase 2: Hypoxic period on FIO2 .10 to .15, establishing pulmonary hypertension; phase 3: Treatment period with NO starting at five parts per million (ppm), doubling dose every 10 min to 80 ppm; phase 4: Posttreatment observation period after discontinuation of NO while maintaining hypoxia for 1 hour or until circulatory failure or pulmonary hypertension of pre-NO magnitude developed. Each animal underwent a maximum of three experiments in random order of hypoxia severity before sacrifice with pentobarbital overdose. Continuous hemodynamic parameters, intermittent cardiac output and pulmonary capillary wedge pressure, and intermittent arterial blood gas analyses were obtained through pulmonary and systemic artery catheters placed by femoral cutdown. Pulmonary and systemic vascular resistances (PVR and SVR) were calculated by standard formulas. Experiments were divided into two groups (n = 8 in each): group 1 with severe hypoxia (PaO2, 25 to 35) and group 2 with moderate hypoxia (PaO2, 36 to 65). Data for all hemodynamic parameters were expressed as mean percentage change from baseline (phase 1) +/- SEM under each set of conditions, and the two groups were compared by two-way analysis of variance and covariance adjusted for order of experimentation.(ABSTRACT TRUNCATED AT 250 WORDS)

Copper metabolism leading to and following acute hepatitis in LEC rats

The accumulation process of copper (Cu) in the liver and the following metabolic disorder of Cu were examined in LEC rats, a mutant strain which accumulates Cu with age and shows spontaneous acute hepatitis and/or hepatoma. Cu concentration in the liver of female rats was approximately 220 micrograms/g liver at 2 weeks of age, decreased to 100 micrograms/g liver at 4-6 weeks, and then started to increase with age linearly to the highest concentration of 250 micrograms/g liver at 16 weeks. Although the Cu level expressed by concentration (microgram/g liver) decreased during weaning, it increased linearly with age when it was expressed by content (mg/liver), indicating a constant and preferential accumulation of Cu in the liver. Cu concentration stopped increasing at 16 weeks in the liver, followed by a sudden decrease to 1/2 the highest level. Biological markers (serum lactate dehydrogenase and glutamic-oxaloacetic transaminase activities) for liver damage started to increase, together with the appearance of signs of jaundice, when Cu attained the highest concentration. Distributions of Cu and zinc (Zn) in the supernatant fraction of the liver indicated that both metals were mostly distributed to metallothionein (MT) and, to a small extent, to superoxide dismutase on a gel filtration column throughout the course of the experiments. Serum Cu concentration started to increase in a form of ceruloplasmin, together with serum marker enzyme activities for liver damage. Cu concentration in the kidneys also started to increase after the increase of serum Cu. The results indicate that Cu accumulates in the form of MT in the liver of LEC rats to a maximum level of approximately 250 micrograms/g liver, and then decreases suddenly with the onset of acute hepatitis. The maximum level seems to be related to the capacity of MT synthesis, and acute hepatitis is assumed to occur when Cu accumulates beyond the capacity. Serum Cu started to increase, from the abnormally low level, when the metal accumulated beyond the capacity of MT synthesis in the liver, and it was partly reabsorbed by the kidneys and the rest was excreted into urine. Changes in iron and zinc levels were determined and discussed in relation to those of Cu.

A small-volume constant-flow air sampling device for thermal desorption GC analysis

A glass syringe with disposable membrane filters was tested as a constant-flow air sampling device. The principle of this sampling device is straightforward: when the syringe is inverted vertically, the syringe plunger falls at a constant speed if an appropriate flow restrictor is connected at the syringe inlet. In case of a 100 ml syringe with two Teflon membrane filters of 0.50 microns in pore size and 3 mm in diameter, the flow rate was 3 ml/min. The flow rate was constant for a 15-minute sampling period when two to eight filters were used as a flow restrictor. A sample volume of less than 50 ml is sufficient for the determination of organic solvent vapor at the ppm level, when gas chromatography with thermal desorption method is employed. Therefore, this sampling device is useful for determining the time-weighted average concentrations of organic solvent vapor in a working environment.

Enhanced synthesis of metallothionein as a possible cause of abnormal copper accumulation in LEC rats

Long-Evans rats with a cinnamon-like coat color (LEC) is an inbred strain accumulating copper (Cu) in the liver abnormally and showing spontaneous hepatitis and hepatoma. The present study was intended to clarify how Cu accumulates in the LEC rat liver. For this purpose, the distribution profiles of Cu and zinc (Zn) and the inducibility of metallothionein (MT) synthesis were examined in the liver between Cu-loaded Long Evans agouti (LEA, the original strain of LEC) rats and were compared with those in control LEC rats. LEA rats (female, five weeks old) were injected subcutaneously with CuCl2 daily at a dose of 3 mg Cu/kg body weight for 2, 4, 6, and 9 days. The concentration of Cu (124 micrograms/g) accumulated in the LEA rat liver after four injections was comparable to that in control LEC rats. Only 20% of Cu in the liver of LEA rats was recovered in the supernatant fraction in the form of MT, while Cu in the LEC rat liver (113 micrograms/g) was recovered mostly in the supernatant fraction, and was bound to MT. Although the increased concentration of Cu in the LEA rat liver was further elevated after additional injections of Cu, the amount of MT did not increase further. The MT mRNA content in the LEA rat liver remained lower than that of LEC rats even after further injections of Cu. Therefore, the present results suggest that LEC rats can accumulate Cu at a high concentration in the liver because of their extremely high inducibility of MT.

[Clinical efficacy of arbekacin on MRSA pneumonia]

Arbekacin sulfate (ABK) was administered by intravenous drip to pneumonia patients infected with methicillin-resistant Staphylococcus aureus (MRSA), and the efficacy and the safety were objectively evaluated by the executive committee. The daily dose was determined in principle as 150-200 mg, two times a day, 30-90 minutes drip infusion, and the dose was to be changed at each special occasion. Combined therapy with other antibiotics was scheduled in severe cases at a decision of the physician in charge. Data of 18 cases were accumulated. The efficacy could be evaluated for 12 cases (4 cases with ABK alone, and 8 cases with combined therapy), and the safety was evaluated for 18 cases. The clinical efficacy was: excellent, 1; good, 4; fair, 5; and poor, 2. The efficacy rate was 41.7%. The bacteriological effect was: eradicated, 2 (16.7%); decreased, 2; and no change, 8. There found no side effects except 3 cases of abnormal laboratory data, two abnormal renal functions(11.1%) and one abnormal hepatic function (5.5%). In one of the renal disorders, decreased dose of ABK improved the function. In the other case, the impaired renal function lasted until death by heart failure. In the case of abnormal function, discontinuing the ABK therapy improved the hepatic function. In the 4 out of 5 cases that showed excellent or good clinical efficacy, patients recovered within relatively early days of ABK therapy. The average days for recovery was 7.8.

Mechanisms for removal of copper from metallothionein by tetrathiomolybdate

Mechanisms for removal of copper (Cu) from metallothionein (MT) by tetrathiomolybdate (TTM) were examined in vivo and in vitro using the LEC rat, which accumulates Cu as MT owing to the hereditary disorder of this strain. In our previous experiment, repeated intraperitoneal injections of TTM were shown to remove approximately two-thirds of the Cu from the liver, and the Cu remaining in the liver changed from soluble MT-bound forms to nonsoluble unidentified forms. The present single intravenous injection of TTM changed only part of the distribution in the soluble fraction, and dimeric MT was assumed to be formed. The liver supernatant was treated in vitro with high and low doses of TTM. The former treatment removed all Cu bound to MT and the Cu distributed to high molecular weight proteins, while the latter treatment produced dimeric MT. The results indicate that Cu accumulated as MT can be removed differently by TTM according to its relative dose both in vivo and in vitro. Excess TTM removes Cu completely from MT, leaving apothionein, while lesser TTM than Cu removes Cu incompletely, leaving MT with unoccupied sulfhydryl groups which coordinate with Cu intermolecularly to form dimeric and polymeric MT through the -S-Cu-S- bridge.

Selective enhancement of metallothionein mRNA expression by copper in primary cultured liver parenchymal cells of LEC rats

Mechanisms for the abnormal copper (Cu) accumulation in the liver of LEC rats were examined using primary cultured liver parenchymal cells prepared from mutant LEC rats and those from control LEA rats (original strain). The Cu and metallothionein (MT) mRNA levels in the liver of LEC rats were caused to decrease to the same levels as those of LEA rats by removing Cu in vivo selectively with tetrathiomolybdate. Cu was taken up by LEC rat cells to the same extent as LEA rat cells by exposure to low medium Cu and to a higher extent by exposure to high medium Cu, while the MT mRNA level in LEC rat cells increased dose-dependently at a much higher rate than that in LEA rats. MT mRNA levels in both cells were comparable by exposure to cadmium, zinc and dexamethasone. The results indicate that expression of MT mRNA is selectively enhanced by Cu in LEC cells despite the fact that uptake of Cu is comparable with normal cells.