High-level expression of human insulin-like growth factor II in Escherichia coli

A gene encoding mature human insulin-like growth factor II (IGF-II) was constructed from the modified IGF-II cDNA sequence and two double-stranded synthetic oligodeoxynucleotide linkers. It was fused to a truncated lacZ gene such that IGF-II was expressed as part of C-terminus of beta-galactosidase. This fused lacZ'-IGF-II gene was under the control of tac promoter and we overproduced the beta-galactosidase-IGF-II fusion protein in the Escherichia coli. The fusion protein formed inclusion bodies inside the cells. The fusion protein was purified from the isolated inclusion bodies and IGF-II protein was obtained from their fusion protein by CNBr cleavage. The released IGF-II was confirmed by its molecular weight as determined by SDS-PAGE and by its ability to bind anti-IGF antibody.

Chronological changes in genetic variance and heritability of systolic and diastolic blood pressure among Chinese twin neonates

In order to examine the chronological changes in genetic variance and heritability of arterial systolic and diastolic blood pressure (SBP and DBP of Chinese infants in Taiwan, a total of 339 same-sexed twin neonates born in four major general teaching hospitals in Taipei City were studied. Based on placentation and 12 red blood cell antigens, 274 monozygotic (MZ) and 65 dizygotic (DZ) twin pairs were identified and followed up to the age of one year. Both SBP and DBP were measured by Doppler blood pressure monitor. Within-pair mean squares of SBP and DBP were consistently smaller in MZ than DZ twins at ages one month and over. The findings remained unchanged after the adjustment for the effects of age, sex, gestational age, placentation and physical state during blood pressure measurement. Falconer's heritability indices for adjusted SBP and DBP at ages two months and over ranged from 0.29 to 0.55 and from 0.27 to 0.45, respectively. The study indicates an important genetic influence on blood pressure during infancy.

Genetic variance and heritability of serum cholesterol and triglycerides among Chinese twin neonates

In order to examine the genetic variance and heritability of serum total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglycerides, a total of 349 pairs of same-sexed twin neonates born in four major general teaching hospitals in Taipei City were studied. Based on the placental pattern and 12 red blood cell antigens, 271 monozygotic (MZ) and 78 dizygotic (DZ) twin pairs were identified. There was a significant genetic variance for total cholesterol, HDL-C, LDL-C, and triglycerides both unadjusted and adjusted for sex, gestational age and placentation. The unadjusted heritability of total cholesterol, HDL-C, LDL-C, and triglycerides was 0.59, 0.30, 0.25 and 0.75, respectively; while the corresponding adjusted heritability was 0.74, 0.38, 0.31, and 0.49, respectively. Intrapair variance of serum lipids was not significantly different between monochorionic and dichorionic MZ twins.

Regulation of the hydrolytic and transfer activities of gamma-glutamyl transpeptidase

The activity of gamma-glutamyl transpeptidase was inhibited and stimulated by hippurate with and without acceptor molecules, respectively. Substrate activation was observed when acceptor molecules was not present but the activation was disappeared by the addition of hippurate. When glutamine was absent the inhibition degree of hippurate at pH 8.0 was greater than at pH 7.0, whereas in the presence of both hippurate and glutamine the results were opposed. These show a possibility that glutaminase is activated by hippurate under the condition of physiological pH. The activation of glutaminase by hippurate was also confirmed directly. The inhibition degree of transfer activity by glutamine was increased along the increase of acceptor concentration only in the presence of hippurate. Gamma-Glu-Phe-Gly satisfying prerequisites for donors doesn't act as a substrate, which shows that L-gamma-glutamyl-p-nitroanilide itself hardly acts as an acceptor. This contradicts to an idea that substrate activation caused by autotranspeptidation. The change of apparent Km and Vmax according to the change of pH in the presence of hippurate was different from that in the presence of acceptors. This shows a possibility that the active site on small subunit is inhibited and the latent active site in large subunit is exposed by the interaction of hippurate to the enzyme.

Renal abnormalities in schoolchildren

To establish prevalence of some renal abnormalities in schoolchildren, an epidemiologic study of 132,686 schoolchildren, including 69,903 boys and 62,783 girls, was conducted from March 1987 to May 1988 in the city of Taipei. At the health station of each school, the students were screened quickly by a physician with portable real-time ultrasound equipment. When a renal abnormality was detected or suspected, the examinee was referred to Taipei Municipal Women and Children's Hospital for further investigation. Radiologic and urologic procedures were then selectively performed to establish the correct diagnosis. Renal abnormalities were detected in 645 students (approximately 0.5% of total population screened). There were 256 cases of hydronephrosis, 103 cases of unilateral renal agenesis, 128 cases of unilateral small kidney, 90 cases of renal cystic disorders, 30 cases of ectopic kidney, and 38 cases of other abnormalities. Surgically correctable lesions were demonstrated in 50 of these students. Rapid renal ultrasonography was found to effectively detect some renal abnormalities initially, and prevalence could then be established after further investigations.

Postpartum subsidence of hepatitis B viral replication in HBeAg-positive carrier mothers

To elucidate the effects of pregnancy and delivery on hepatitis B e antigen (HBeAg)-positive carrier mothers, 31 HBeAg-positive carrier mothers were followed-up postpartum 1 year, with 30 HBeAg-positive nonpregnant female carriers as controls. Serum hepatitis B surface antigen (HBsAg), HBeAg titer, and hepatitis B virus (HBV)-DNA concentration were studied at defined intervals. The results revealed that in the control group HBeAg titers and HBV-DNA concentrations fluctuated, whereas the HBsAg titers showed little change, but HBeAg clearance or seroconversion to anti-HBe were not noted on follow-up. In contrast, one carrier mother seroconverted to anti-HBe during pregnancy and the antibody persisted thereafter. Five of the remaining 30 carrier mothers cleared HBeAg postpartum, and among these five cases, one also seroconverted to anti-HBe. In addition, in another five of the 30 cases, the HBV-DNA fell to undetectable level (less than 0.04 ng/ml). All these ten cases had a common tendency of showing a decrease in HBeAg titers and/or HBV-DNA concentrations 1-2 months after delivery. The HBeAg titers and HBV-DNA concentrations in the other 11 cases remained unchanged, whereas the remaining nine cases had increased levels. It is concluded that subsidence of HBV replication is precipitated by delivery in one-third of HBeAg-positive carrier mothers in Taiwan, and this occurs most frequently 1-2 months postpartum.

Immunosuppressive effects of 2-acetylaminofluorene and 2-aminofluorene on murine splenocytes culture

The immunosuppressive effects of 2-acetylaminofluorene (AAF) and 2-aminofluorene (AF) were studied in BALB/c mouse splenocyte culture. Direct addition of AAF and AF to the splenocyte culture produced a dose-related suppression of the in vitro antibody response to sheep erythrocytes(SRBC), DNP-Ficoll, and lipopolysaccharide(LPS). AAF and AF also produced suppression on lymphoproliferative responses to LPS and concanavalin A(Con A). The immunosuppressive effects of AAF and AF, however, were diminished when AAF and AF were incubated in the splenocyte-hepatocyte coculture system for 4 hr. When hepatocyte cultures were pretreated with SKF 525A, a cytochrome P-450 inhibitor, before coculture with spleen cell along with AAF and AF, the suppression of in vitro antibody response reappeared. Meanwhile, both AAF and AF produced a dose-related DNA single-strand breaks in spleen cells only if AAF and AF were treated to spleen cells cocultured with hepatocytes. These results indicate that the immunosuppression by AAF and AF is not mediated by the reactive metabolites implicated to DNA damage.

Production of DNA single-strand breaks in unstimulated splenocytes by dimethylnitrosamine

In an attempt to elucidate the mechanism whereby primary hepatocytes, but not liver S9 homogenates, generate immunosupprssive metabolites of dimethylnitrosamine (DMN), the production of DNA single-strand breaks (SSB) in unstimulated splenocytes was investigated with alkaline-elution analysis. Both hepatocytes and S9 homogenates induced SSB in cultured splenocytes by DMN - minimum detectable doses with the two metabolic activation systems (MAS) were 1 microM and 5 mM, respectively. DNA elution profiles were linear in splenocytes co-cultured with DMN and hepatocytes and convex in splenocytes incubated with DMN and S9 homogenates. Aminoacetonitrile (AAN; 10 mM), a DMN demethylase inhibitor, reversed SSB in splenocytes when incubated with either MAS. Addition of exogenous calf-thymus DNA to the hepatocyte co-culture medium did not affect the production of SSB. Rocking the hepatocyte-splenocyte cultures changed the elution profile from linear to convex. All of these treatments have been previously shown to block the immunosuppression by DMN in the hepatocyte co-culture system. These results indicate that the immunosuppression by DMN is not related to DNA damage, as measured by the production of SSB, and suggest that the metabolism of DMN to intermediates capable of producing genotoxicity and immunotoxicity may be qualitatively and/or quantitatively different.

The effects of altered strain environments on bone tissue kinetics

This study defines the alteration in bone tissue kinetics responsible for the "adaptive remodeling" response to altered strain environments. Adult beagle dogs were separated into three experimental groups: ulnar osteotomy, ulnar osteotomy with fracture fixation plate spanning the gap and sham surgery. Four sets of double fluorochrome labels were administered. Prior to sacrifice at 1, 3, and 6 months, strains were measured through rosette strain gages on the cranial and caudal surfaces of the intact radius. Histomorphometric analysis indicated that the increased bone mass in response to elevated strain results from increased activation frequency of modeling with more sites undergoing formation processes than resorption processes on periosteal and endocortical surfaces. Increased remodeling activation did not lead to increased bone mass. There was no evidence that elevated strain changes the individual vigor of osteoclasts or osteoblasts, or that the sigma period was altered by elevated strain.

Parental occupational lead exposure and lead concentration of newborn cord blood

The purpose of this study was to determine the influence of parental occupational lead exposure on the lead levels of newborn cord blood in the Taipei area. From September 1984 to June 1985, 5,000 pregnant women voluntarily participated in the study at the Taipei Municipal Maternal and Child Hospital. Each woman was interviewed regarding her and her husband's occupational exposures; 2,948 successfully delivered healthy newborns, and cord blood samples were obtained using Terumo Venoject, and 242 samples were analyzed by graphite furnace atomic absorption spectrometry using an Instrumentation Laboratory 251 instrument. Nine cord blood samples were from newborns with both parents exposed, 26 samples had maternal exposure only, 105 samples had paternal exposure only, and 102 were nonexposed. The results showed that the average lead level of cord blood with both parents exposed was 8.9 +/- 2.9 micrograms%, maternal exposure 9.0 +/- 3.8 micrograms%, paternal exposure 8.3 +/- 3.4 micrograms%, and 6.9 +/- 3.2 micrograms% in the nonexposed group. There were significant differences between the nonexposed and the maternal exposure groups, and also between the nonexposed and paternal exposure groups. All 26 maternal exposures were from lead soldering operations. Multivariate analysis revealed that, after control of father's exposure status, newborn cord blood lead level increased 0.27 micrograms% for each hour the mother spent on lead soldering during a normal working day, thus suggesting that soldering during pregnancy may be hazardous to newborns. Paternal contribution to the cord blood lead levels seemed to be through either working at home with the pregnant mother also at home or bringing work clothes home for laundering.

Clinical significance of the immunological tests in rheumatoid arthritis

Of the many theoretical causes of rheumatoid arthritis(RA), the most widely held theory is the autoimmune mechanism. In order to clarify the clinical significance of the immunological tests in RA, we studied immunoglobulin and complement levels in sera and synovial fluids of 118 RA patients and the following results were obtained. 1) The levels of immunoglobulins were elevated in both serum and synovial fluid and this was more prominent in the seropositive cases than the seronegative ones. 2) The levels of C3 component were decreased in both serum and synovial fluid, while those of C4 were decreased only in synovial fluid. Serum C3 and C4 component levels were more decreased in the seropositive cases than the seronegative ones. 3) The immunoglobulin levels in serum (IgG, IgM and IgA) and synovial fluid (IgG and IgA) and the levels of C3, C4 component in serum were well correlated with the clinical forms of rheumatoid arthritis. 4) The IgA level in serum and IgM level in synovial fluid were more increased in the exacerbated cases than the chronic ones. 5) Serum IgG level was decreased after steroid medication over one month.

Skeletal change in response to altered strain environments: is woven bone a response to elevated strain?

Studies demonstrate that geometric changes in bone architecture in response to altered mechanical strain occur through the formation of woven bone. The goal of this study was to test the hypothesis that these changes are partly the result of surgical manipulation rather than a true adaptive response to altered strain. Beagle dogs were subjected to either an ulnar osteotomy, an osteotomy with plate fixation, or sham operation. Strains on the radius were measured just prior to sacrifice 1, 3 or 6 months after surgery. Our results support the idea that woven bone can be a normal response to an abnormal strain environment if the mechanical challenge is intense enough; that elevated mechanical strains can cause the endocortical bone envelope to revert to a state of net formation; and that "adaptive remodeling" in adults in response to a change in mechanical strain may be a special case of modeling in which resorption is not required prior to formation at a particular skeletal site.

Experimental verification of facet load transmission by direct measurement of facet lamina contact pressure

This paper presents results of a new measuring technique by means of which facet tip contact pressure data were obtained. The aim of the paper is to demonstrate by direct measurement the existence of a load transmission mechanism through the facet joint. Six lumbar spine motion segments were used in 21 tests. Simulated extensor muscle action was provided to overcome moments due to eccentric loads which represented body weight and an external hand-held load acting 340 mm anterior to the center of the disc. Facet pressure was measured in all cases when muscle load was applied to counteract body weight. This pressure increased when more muscle force was applied to balance the externally applied flexion moment. When the anterior load was released suddenly, there was a large increase in facet pressure with a concomitant decrease in disc pressure.

Role of the transfer of metabolites from hepatocytes to splenocytes in the suppression of in vitro antibody response by dimethylnitrosamine

The metabolism and subsequent immunosuppressive effects of dimethylnitrosamine (DMN) were investigated in mixed cultures of mouse hepatocytes and mouse splenocytes. Hepatocytes were shown to activate DMN to an immunosuppressive form that caused the suppression of the in vitro antibody response to the T-dependent antigen, sheep erythrocytes (SRBC). A significant increase in the binding of DMN metabolites to trichloroacetic acid (TCA) precipitable material in splenocytes was induced when 94 microM [14C-methyl]DMN was added to the co-culture medium, indicating that reactive intermediates of DMN were transferred from hepatocytes to splenocytes and resulted in alkylation of macromolecules in splenocytes. The amount of [14C]DMN bound to TCA precipitable material in splenocytes increased in a time-dependent manner up to 4 hr of incubation. Aminoacetonitrile (AAN), a high-affinity DMN demethylase inhibitor, reversed the suppression by low concentrations of DMN (0.5 to 5 mM), but not by high concentrations of DMN (greater than 5 mM). AAN also inhibited the binding of [14C]DMN to both hepatocytes and splenocytes. These results suggest that reactive metabolites of DMN are released from hepatocytes and that the suppression of the antibody response by DMN is mediated via these reactive intermediates.

The subunit composition of Portunus trituberculatus hemocyanin polymers

The subunit composition of isolated polymeric forms of Portunus trituberculatus hemocyanin were analysed by immunological techniques. The dodecamers contain four monomeric subunits corresponding to subunits I, II, III and IV, whereas the hexamers are devoid of subunit IV. These results suggest that subunit IV is required as a joining piece for the assembly of dodecamers.

Presence of hexobarbital in primary cultures of rat hepatocytes maintains cytochrome P-450 levels and drug metabolizing enzyme activities

Addition of hexobarbital (1 mM) to the culture medium of rat hepatocytes protected against the rapid decline in the level of cytochrome P-450 and the activities of various drug metabolizing enzymes. While the hepatocytes cultured for 72 hr without hexobarbital had only 30% of their original level of cytochrome P-450, the cells maintained with hexobarbital had 75% of the initial level of the hemoprotein. After 72 hr in culture, the activities of aminopyrine N-demethylase and biphenyl 4-hydroxylase were 22-24% of the original rate for the nontreated cells and 73-78% for the hexobarbital treated cells. The activities of 7-ethoxycoumarin O-deethylase and aryl hydrocarbon hydroxylase in the cultures of treated cells were even higher than those of the freshly isolated hepatocytes. Additions of other substrates of hepatic mixed function oxidase to the culture medium did not protect against the loss of cytochrome P-450 and enzyme activities.

Clinical features of Crohn's disease in Korea

Crohn’s disease is a rare disease in Korea, and only 45 cases have been reported during a 34 year from 1952 to 1985. The male to female ratio was about 1.3 to 1 with a slight preponderance of males. The age at diagnosis ranged from 8 to 72 (mean 35.5) years, and the peak incidence occurred in the 3rd, 4th and 5th decades and declined thereafter. More than two thirds of the cases had a grossly demonstrable lesion involving the small bowel including the terminal ileum. The proportion of the patients with macroscopic disease confined to the large bowel alone was only 15 per cent. Abdominal pain was common presenting in 89 per cent of the patients, while such symptoms as fever, hematochezia and diarrhea were not common. Abdominal mass was palpable in more than half the cases, which made it difficult to differentiate Crohn’s disease from cancer of the colon, especially from the one with a predominant infiltration of the bowel wall and a secondary ulcer formation. That is one of the reasons why most cases in korea have been reported by surgeons. A wide variety of complications were present, of which small bowel obstruction was the most common. Other complications were free perforation, malnutrition, fistula formation, hemorrhage and abscess formation in decreasing order. The incidence of symptomatic perianal diseas was only 11 per cent, and this might be due to the small proportion of the disesase confined to large bowel. Extraintestinal manifestations were also rare, and only three patients presented the symptoms of arthritis. Other systemic features such as liver disease, skin lesions, eye complicaitons were absent.

Suppression of in vitro antibody production by dimethylnitrosamine in mixed cultures of mouse primary hepatocytes and mouse splenocytes

The suppression of in vitro antibody responses by dimethylnitrosamine (DMN) was produced in a mouse hepatocyte and splenocyte co-culture system. Mouse hepatocytes were isolated from female B6C3F1 mice and cultured for 20-24 hr to allow the formation of a monolayer on collagen-coated plastic petri dishes. Spleen cells were isolated from the same hybrid and were co-cultured with the hepatocytes along with DMN. Cyclophosphamide (CP), an immunosuppressive agent requiring metabolic activation that was included as an initial positive control, produced a marked suppression of the in vitro antibody responses to LPS, DNP-Ficoll, and SRBCs in 4 hr in the co-culture system. Under comparable conditions DMN markedly suppressed the response to SRBCs, marginally suppressed the response to DNP-Ficoll, and did not suppress the polyclonal response to LPS. The suppression by DMN was related to the rocking speed during the 4-hr co-culture period and was optimally produced when the cultures were not rocked. Addition of serum into the medium (10% fetal calf serum) during the co-culture period did not change the effects of DMN on the antibody response. However, the addition of extracellular DNA (1 mg calf thymus DNA/ml) prevented the suppression of the antibody response by DMN. These results suggest that DNA represents the primary macromolecular target for the reactive intermediate of DMN, and indicate that a syngeneic co-culture system can be used to characterize the in vitro immunosuppression

Immunosuppression induced by chemicals requiring metabolic activation in mixed cultures of rat hepatocytes and murine splenocytes

Primary cultures of adult rat hepatocytes (Fischer 344) were used as an in vitro metabolic activation system in immunotoxicological assays. Rat hepatocytes were isolated by a collagenase perfusion technique and cultured for 20 to 24 hr to allow the formation of a monolayer on collagen-coated plastic petri dishes. Spleen cells isolated from (C57BL/6 X C3H)F1 mice were cocultured with the hepatocytes along with the chemicals. Cyclophosphamide (CP) and Aflatoxin B1 (AFB1) were effectively activated in this coculture system and produced a dose-related suppression of the in vitro antibody responses to LPS, DNP-Ficoll, and SRBC in 3 hr. Neither CP (1 mM) nor AFB1 (10(-4) M) cultured with spleen cells alone produced any effects. Both CP and AFB1 also produced a dose-related suppression of the proliferative responses to LPS, Con A, and PHA. In contrast, up to 100 mM of N-nitrosodimethylamine (DMN) did not suppress any of these assays after a 3-hr incubation in the coculture system. These results indicate that a coculture system can be used to characterize the activity of immunosuppressive chemicals requiring metabolic activation.

Mechanism of facet load transmission as a hypothesis for low-back pain

Low-back pain has a complex and multi-faceted etiology. The articular facets have been shown to be load-bearing structures and may be a site for low-back pain. The aim of this paper is to establish the mechanism for the transmission of axial load across a facet joint and to propose a facet-related hypothesis for low-back pain. The mechanism of load transmission was studied by two methods. Lumbar segments were instrumented with an intervertebral load cell (IVLC) to measure disc load so that facet load could be deduced. The applied load was moved 10 mm anteriorly and 12.5 mm posteriorly from the center of the vertebral body. The facets then were separated from the body and loaded axially to determine their stiffness in tension and compression and to observe the failure mode of the joint. It was shown optically that compressive loading of the isolated facet joints was equivalent to spinal extension and tensile loading to spinal flexion. Lastly, a finite element model of a lumbar motion segment was developed to simulate the transmission of facet load and to study the effects of disc degeneration on facet loads. Results of the study on six lumbar segments revealed that the normal facets carried 3-25%. If the facet joint was arthritic, the load could be as high as 47%. Experiments on isolated facet joints revealed that they behaved as a stiffening spring in compression and were weak in tension.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of DNA single-strand breaks induced by procarcinogens in Chinese hamster ovary cells cocultured with rat hepatocytes

DNA single-strand breaks induced by procarcinogens were detected in Chinese hamster ovary (CHO) cells cocultured with adult rat hepatocytes. Freshly isolated adult rat hepatocytes were added to the CHO cell culture prelabeled with [3H]thymidine. After allowing the hepatocytes to attach on or near the CHO cells, aflatoxin B1 or benzo[a]pyrene was added to the culture and incubated for the desired time. DNA single-strand breaks in CHO cells were measured by the alkaline elution technique. Aflatoxin B1 induced some DNA single-strand breaks in CHO cells cultured alone, but in coculture system with hepatocytes the number of DNA single-strand breaks increased greatly. The magnitude of the increase was related to the dose and the time of exposure to aflatoxin B1. Addition of proteinase-K to the cell lysates increased the elution of DNA compared to that of samples without proteinase-K. Benzo[a]pyrene did not induce any DNA single-strand breaks in CHO cells in the absence of liver cells, but a significant number of single-strand breaks were detected in the coculture system.

Effects of butylated hydroxytoluene (BHT) on biliary excretion of xenobiotics and bile flow in rats

A significant enhancement in the biliary excretion of iv injected sulfobromophthalein (BSP), phenol- 3,6 -dibromphthalein disulfonate (DBSP), procaine amide ethobromide (PAEB) and ouabain was observed in rats maintained on diets containing 0.25% BHT for periods of 10 days. The enhanced biliary excretion of these drugs in BHT treated rats appears to be correlated with the increase in bile flow produced by BHT. The increased bile flow was due to an increase in canalicular bile production rather than a change in net ductular secretion or reabsorption of fluid since bile to plasma concentration ratios of erythritol were unchanged and no permeability change in the biliary tree was observed when mannitol was administered by retrograde intrabiliary injection. The increase in bile flow was not due to an enhanced excretion of bile salts into bile, because both the biliary bile acid concentration and total biliary excretion of bile acids were lower in BHT-treated rats than in control rats. It appears that the increase in bile flow produced by BHT is due to the osmotic choleresis related to the secretion of BHT and its metabolites into bile.

Effects of halogenated dibenzo-p-dioxins on plasma disappearance and biliary excretion of ouabain in rats

A single dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,7-tribromodibenzo-p-dioxin (2,3,7-TBDD), 1,2,3,7,8,9-hexachlorodibenzo-p-dioxin (1,2,3,7,8,9-HCDD), 1,2,4,6,7,9-hexachlorodibenzo-p-dioxin (1,2,4,6,7,9-HCDD), or 1,3,6,8-tetrachlorodibenzo-p-dioxin (1,3,6,8-TCDD) was given to male rats (25 micrograms/kg, p.o.) and plasma concentration and biliary excretion of ouabain assessed 10 days later. Treatment of TCDD, 2,3,7-TBDD and to a lesser extent 1,2,3,7,8,9-HCDD increased the plasma concentration of ouabain and decreased its excretion into ouabain. TCDD, 2,3,7-TBDD and to a lesser extent, 1,2,3,7,8,9-HCDD decreased the bile flow. Liver wet weight was increased in TCDD and 2,3,7-TBDD treated rats. The magnitude of depression in ouabain excretion by those compounds was closely related to the reported relative binding affinity of the compound to liver cytosol and their induction potency of aryl hydrocarbon hydroxylase activity.

Protective effect of Aucuba japonica against carbon tetrachloride-induced liver damage in rats

Pretreatment of rats with ethanol extract from leaves of Aucuba japonica (600 mg/kg/day, po) for two days protected against CCl4-induced depression in plasma disappearance and biliary excretion of injected sulfobromophthalein (BSP) determined 24 hr after the CCl4 challenge (0.5 ml/kg, ip). Percent recovery of BSP in bile in 60 min for control, CCl4, extract + CCl4 treated rats was 66.8 +/- 1.9, 56.2 +/- 1.4, and 68.9 +/- 2.2, respectively. Pretreatment of the extract also protected CCl4-induced increased serum glutamic-pyruvic transaminase activity and liver necrosis as demonstrated by histological evaluations. However, pretreatment of the extract did not modify the intensity of CCl4-induced lipid peroxidation process or cytochrome P-450 destruction. The results suggest that ethanol extract of Aucuba japonica protects CCl4 hepatotoxicity at a site in the chain events leading to necrosis but not the activation step of CCl4 to X CCl3 and X C1 free radicals.

Protective activities of aucubin against carbon tetrachloride-induced liver damage in mice

An iridoid glucoside, aucubin was isolated from Aucuba japonica leaves and its protective activities against CCl4-induced hepatotoxicity were evaluated by measuring the duration of hypnosis induced by hexobarbital after CCl4 challenge (0.2 ml/kg/day, po) and the levels of serum glutamic-oxalacetic (GOT) and serum glutamic-pyruvic transaminase (GPT). The duration of hypnosis for the saline control group, the CCl4 alone treated group and the aucubin plus CCl4 treated group was 24.8 +/- 8.5, 60.5 +/- 9.5 and 28.0 +/- 3.2 min, respectively. Treatment of mice with aucubin also effectively protected against CCl4-induced increased serum GOT and GPT activities. It was found that aucubin inhibited hepatic RNA and protein syntheses in vivo. Such inhibitory effects of aucubin might be responsible for protective activities against CCl4-induced liver damage.

Water vapor sorption and desorption by human callus I: Anomalous diffusion

The rates of sorption and desorption of water in membranes of varying thickness of excised human callus were determined for several relative vapor pressures and temperatures. Under the conditions studied, the diffusion of water in these membranes was interpreted as non-Fickian in nature. It was concluded that at low water concentration this type of membrane exists in the glassy state. The effect of the relative vapor pressure on the water sorption rates was examined in the context of the free volume theory.

Production of Botulinum Toxin in Inoculated Pack Studies of Foil-Wrapped Baked Potatoes

Idaho Russet Burbank potatoes were surface or stab inoculated with 10 to 10⁵ spores of Clostridium botulinum type A strain, overwrapped in aluminum foil, baked at 204 C for 50 min or 96 C for 3 h and then held at 22 or 30 C. The shortest incubations resulting in the first botulinogenic potatoes were inversely related to spore doses and ranged from 3 to 7 days; potatoes inoculated with 10 spores were toxic after 5 to 7 days. Total toxin in individual potatoes incubated 3 to 5 days were 5 × 10³ to 5 × 10⁵ mouse mean lethal doses. Toxin was not found at distances greater than 1.6 cm from the spore inoculation site. Results indicate that left-over, foil-wrapped, baked potatoes are a perishable food that must be refrigerated.

In vivo methotrexate transport in murine Lewis lung tumor

Methotrexate uptake by murine Lewis lung tumor was measured in vivo over a wide dose range. The data were analyzed according to a model previously developed for tissues in which methotrexate uptake is rate limited by transport across the cell membrane. Methotrexate transport in this tumor followed Michaelis-Menten kinetics with a rate constant for permeability (k/K) of 0.012 min-1. The methotrexate binding capacity of dihydrofolate reductase in the tumor was not exceeded at any dose studied. A low membrane permeability in conjunction with a high dihydrofolate reductase level explains the resistance of this tumor to methotrexate.

Relative biochemical aspects of low and high doses of methotrexate in mice

During low infusion rates of methotrexate (1.0 microng/hr/mouse; plateau plasma concentration, 2 X 10(-8) M), [3H]deoxyuridine incorporation into DNA was inhibited to a significant degree in small intestine and femur marrows. However, incorporation of [3H]thymidine into intestinal DNA was stimulated at this low infusion rate. During high infusion rates of methotrexate (10 microng/hr/mouse, plateau plasma concentration, 4 X 10(-7) M), inhibition of the incorporation of [3H]deoxyuridine at the steady state levels of plasma methotrexate in both the small intestine and femur marrow was significant. In contrast to stimulation at the low infusion rate, incorporation of [3H]thymidine into intestinal DNA at this high infusion rate was inhibited to a significant degree. Inhibition was not statistically significant in femur marrow DNA. The inhibition of [3H]thymidine into intestinal DNA could be reversed by the simultaneous infusion of inosine. Thus, in the in vivo system, an antipurine effect on DNA Synthesis at high methotrexate plasma concentration in the small intestine was observed. This antipurine effect was not apparent at the lower concentrations. The lower concentration, however, could still inhibit [3H]deoxyuridine incorporation into intestinal and femur marrow DNA to a significant enough degree that, if prolonged, it would resultin lethality to the mice. The thymineless state can be maintained for at most 60 hr in mice without lethal toxicity, whereas the antipurine state can be maintained for no longer than 18 hr in mice without some lethal toxicity. These data have important implications in rescue studies using thymidine or leucovorin.

Growth potential of Clostridium botulinum in fresh mushrooms packaged in semipermeable plastic film

Fresh mushrooms (Agaricus bisporus) were inoculated in the stem, gill, or cap with Clostridium botulinum spores. They were placed with uninoculated mushrooms in paper board trays, which were then covered and sealed in a polyvinyl chloride stretch film to simulate prepackaged mushrooms available at retail stores. When incubated at 20 C, botulinum toxin could be detected as early as day 3, or 4, when the mushrooms still appear edible. Mushrooms inoculated in the stem with 1,000 type A spores frequently became botulinogenic; higher spore levels were needed if gills or caps were inoculation sites. Type B spores were less apt to produce toxic mushrooms. Respiration of the fresh mushrooms used up O2 more rapidly than could enter through the semipermeable wrapping film, so that the equilibrium O2 concentration became low enough for growth of C. botulinum. Inoculated mushrooms did not become botulinogenic when held at 4 C.

Purification and properties of Clostridium botulinum type F toxin

Clostridium botulinum type F toxin of proteolytic Langeland strain was purified. Toxin in whole cultures was precipitated with (NH4)2SO4. Extract of the precipitate was successively chromatographed on diethylaminoethyl-cellulose at pH 6,0, O-(carboxymethyl) cellulose at pH 4.9, and finally diethylaminoethyl-cellulose at pH 8.1. The procedure recovered 14 percent of the toxin assayed in the starting culture. The toxin was homogeneous by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, double gel diffusion serology, and isoelectric focusing. Purified toxin had a molecular weight of 150,000 by gel filtration and 155,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Specific toxicity was 9.6 X 10-6 mean lethal doses per absorbancy (278 nm) unit. Sub-units of 105,000 and 56,000 molecular weight are found when purified toxin is treated with a disulfide reducing agent and electrophoresed on sodium dodecyl sulfate-polyacrylamide gels. Reciprocal cross neutralizations were demonstrated when purified type F and E toxins were reacted with antitoxins which were obtained with immunizing toxoids prepared with purified toxins.

Calculation of coupling losses between light emitting diodes and low-loss optical fibers

We have investigated the problem of coupling light emitting diodes to contemporary low-loss multimode optical fibers (NA ~ 0.14) for optical communications. We have calculated the maximum coupled light power and the coupling efficiencies for a disk geometry and a strip geometry with and without a lens. In our calculations, we assumed that the homostructure LED has a radiance of 30 W/sr cm(2) and requires an electrical power input JV or 2 x 10(4) W/cm(2). In the disk geometry without a lens, the maximum coupled light power of 36 microW can be achieved. With a lens the LED junction area can be reduced so that the coupled light power of 31 microW, which is 0.1% of the input electric power, is possible. In the strip geometry with a lens a coupled light power of 260 microW is achievable.