A new red-region substrate, tetra-substituted amino aluminium phthalocyanine, for the fluorimetric determination of H2O2 catalyzed by mimetic peroxidases

A new red-region fluorogenic substrate, tetra-substituted amino aluminium pthalocyanine, was developed for the selective determination of H2O2 based on the catalytic effect of mimetic peroxidases, viz., hemin or iron tetrasulfonatophthalocyanine (FeTSPc). Under the optimum conditions, the linearity of the calibration graph for the determination of H2O2 with hemin (or FeTSPc) as the catalyst was in the range from 0.0 to 3.0 x 10(-7) mol L-1 (or from 0.0 to 2.0 x 10(-6) mol L-1). The detection limits were 3.7 x 10(-9) and 4.9 x 10(-9) mol L-1 H2O2, respectively. The relative standard deviation (n = 7) was within 1.5% in the middle of the linear range. The peroxidase activity of the mimetic enzymes hemin and FeTSPc, the effects of some experimental conditions and the influence of foreign substances were investigated. With this substrate, 0.0-7.5 x 10(-8) mol L-1 hemin and 0.0-2.0 x 10(-6) mol L-1 FeTSPc can be determined with an accuracy and precision of about 1.3%. The potential application of the reagent was tested by the determination of H2O2 in rainwater.

Sensitive fluorimetric determination of formaldehyde by the co-quenching effect of formaldehyde and sulfite on the fluorescence of tetra-substituted amino aluminium phthalocyanine

A novel and sensitive fluorimetric method was developed for the determination of formaldehyde based on the co-quenching effect of formaldehyde and sulfite on the fluorescence of tetra-substituted amino aluminium phthalocyanine. Formaldehyde in the concentration range 0.040-1.19 micrograms ml-1 can be determined with a limit of detection of 7.5 ng ml-1. The relative standard deviation for nine replicate measurements of 80.0 ng ml-1 formaldehyde is 1.8%. The method was applied to the analysis of real samples with satisfactory results.

A novel mimetic enzymatic fluorescence immunoassay for hepatitis B surface antigen by using a thermal phase separating polymer

Iron tetrasulfonatophthalocyanine (FeTSPc), a peroxidase mimic, was used as a labeling reagent and poly(N-isopropylacrylamide) (PNIP) as the separation support of the immune complex for the mimetic-enzymatic immunoassay of hepatitis B surface antigen (HBsAg). PNIP was precipitated from aqueous solution when the ambient temperature was higher than its lower critical solution temperature of 31 degrees C. In a sandwich immunoassay, the antigen (HBsAg) first reacted with mouse anti-human HBsAg antibody immobilized on PNIP (PNIP-antibody) and then further reacted with FeTSPc-labeled mouse anti-HBsAg antibody (antibody-FeTSPc) at room temperature in a homogeneous format. After changing the temperature to separate the PNIP-antibody-HBsAg-antibody-FeTSPc conjugate moiety, it was re-dissolved and determined by coupling with the fluorogenic reaction of hydrogen peroxide and p-hydroxyphenylpropionic acid. The sensitivity of this method (3 ng mL-1) was close to that of the traditional ELISA using the same reactants. However, the assay was much faster (the assay time decreased from 100-120 to 45 min). This method was applied to determine HBsAg in human serum with satisfactory results.

A novel method for the determination of total protein in human serum by near infrared fluorescence recovery

A novel fluorometric method has been developed for the determination of total protein in human serum with a new near-IR reagent as a fluorescence probe, based on the fluorescence recovery of the cyanine-CTAB system in the presence of protein. Maximum fluorescence is produced with maximum excitation and emission wave-lengths at 765 and 812 nm, respectively. Under optimal conditions, the calibration graphs are linear over the range 0.4-12.0 microg/mL for protein. The detection limit is 70 ng/mL, and the relative standard deviation of six replicate measurements is 1.14% for 6.0 microg/mL protein. The results are satisfactory.

Chiropractic care for children

OBJECTIVE

To describe the practice characteristics and pediatric care of chiropractors.

STUDY DESIGN

Cross-sectional, descriptive survey.

SETTING

Chiropractic practices in the Boston, Mass, metropolitan area.

PARTICIPANTS

One hundred fifty licensed chiropractors.

MAIN OUTCOME MEASURES

Demographics, practice characteristics, and fee structure. Practitioners were also asked about their approach to childhood immunizations and a clinical scenario. Data were analyzed using simple descriptive statistics.

RESULTS

Ninety (60%) chiropractors responded. All were white and 65% were men. Respondents had on average 122 patient visits weekly, of which 13 (11%) were from children and adolescents. Typical visit frequency ranged from 1 to 3 times weekly. Average visit fees were $82 and $38 (initial and follow-up) and 49% of the fees were covered by insurance. Seventy percent of the respondents recommended herbs and dietary supplements. For pediatric care, 30% reported actively recommending childhood immunizations; presented with a hypothetical 2-week-old neonate with a fever, 17% would treat the patient themselves rather than immediately refer the patient to a doctor of medicine, doctor of osteopathy, or an emergency facility.

CONCLUSIONS

Children and adolescents constitute a substantial number of patients in chiropractics. An estimated 420000 pediatric chiropractic visits were made in the Boston metropolitan area in 1998, costing approximately $14 million. Pediatric chiropractic care is often inconsistent with recommended medical guidelines. National studies are needed to assess the safety, efficacy, and cost of chiropractic care for children.

Determination of proteins at nanogram levels by their quenching effect on large particle scattering of colloidal silver chloride

A novel quantitative method for the determination of proteins in aqueous solutions has been based on the quenching of the resonance scattering light of colloidal silver chloride in the presence of proteins. The detection limits for eight kinds of proteins (BSA, HSA, egg albumin, human gamma-IgG,alpha-chymotrypsin, E. Coli. alpsase, myoglobin, alpha-casein) were at about 8 ng/mL; the linear ranges of the calibration curves were 10-400 ng/mL under optimal conditions,except for human gamma-IgG (20-400 ng/mL), myoglobin (10-300 ng/mL), and alpha-casein (10-300 ng/mL). Three wavelengths (398 nm, 475 nm, 499 nm) were all suitable for the determination and any acidity from pH 3.0 to pH 9.0 could be chosen. A few non-protein substances at high concentration levels interfered with this method, but this problem could simply be overcome by diluting the samples before the assay. Mechanism studies showed that the quenching effect of proteins on the scattering light of colloidal silver chloride was mainly due to the coagulation of AgCl particles retarded by protein. The method was employed for the determination of total protein in human serum with satisfactory results.

Improvement of osseointegration of titanium dental implants by a modified sandblasting surface treatment: an in vivo interfacial biomechanics study

To study the effects of a modified sandblasting surface treatment on the osseointegration of dental implants at the level of interfacial biomechanics, an in vivo pullout test was conducted using bone-interfacial shear strength as a criterion. Titanium implants were inserted into the medialis condyli of dogs and harvested 2, 4, and 12 weeks after insertion. Shear strength was determined with an Instron pullout tester. Observation and analysis of the surface of modified sandblasted implants after pullout at 12 weeks were performed with scanning electron microscopy and x-ray spectroscopy. Results showed that the shear strength of implants with a modified sandblasted surface was about five times as high as that of implants with a smooth surface. We concluded that the rough surface of titanium dental implants created by the modified sandblasting treatment can greatly enhance the shear strength at the dental implant-bone interface and that, with this enhancement, the secondary micropores play a much more important role in implant-bone bonding.

Cationic cyanine as a near-infrared fluorescent probe for the determination of nucleic acids

A new method with a cationic near-IR cyanine as fluorescent probe was developed for the determination of nucleic acids. The near-IR cyanine shows maximum excitation and emission wavelengths at 765 and 790 nm, respectively, in aqueous solution. The method is based on the fluorescence decrease of near-IR cyanine in the presence of nucleic acids. Under optimal conditions, the ratio of fluorescence intensity in the absence and presence of nucleic acids was proportional to the concentration of nucleic acids over the range 0.10-1.2 microg/mL for CT (calf thymus) DNA or SM (salmon sperm) DNA, and 0.10-1.6 microg/mL for yeast RNA. The detection limits were 30 ng/mL for CT DNA, 25 ng/mL for SM DNA and 70 ng/mL for yeast RNA. The relative standard deviation (n = 6) was 2.1% for 500 ng/mL CT DNA, 2.4% for 500 ng/mL SM DNA and 2.7% for 500 ng/mL yeast RNA, respectively.

Application of magdala red as a fluorescence probe in the determination of nucleic acids

A fluorescence quenching method was developed for the rapid determination of DNA and RNA using magdala red as fluorescence probe. In weakly acidic medium, the fluorescence of magdala red (lambdaex/lambdaem = 540/555 nm) can be largely quenched by DNA or RNA. The calibration graphs are linear over the range 0.01-1.2 microg/mL for both calf thymus DNA (CT DNA) and salmon DNA (SM DNA), and 0.015-1.0 microg/mL for yeast RNA, respectively. The corresponding detection limits are 6.0 ng/mL for CT DNA, 7.0 ng/mL for SM DNA and 15.0 ng/mL for yeast RNA, respectively. CT DNA could be determined in the presence of 20% (w/w) yeast RNA, and the relative standard deviation of six replicate measurements is 3.18% for 400 ng/mL of CT DNA. Interference from coexisting substances in the determination of DNA was also examined. Real samples were determined with satisfactory results.

Woodchuck lymphotoxin-alpha, -beta and tumor necrosis factor genes: structure, characterization and biological activity

We cloned and characterized the woodchuck tumor necrosis factor (TNF) and lymphotoxin-alpha, -beta (LT-alpha, -beta) cDNAs, genes and proteins to facilitate study of the functions of these cytokines during the course of woodchuck hepatitis virus (WHV) infection. Woodchuck cDNA and genomic DNA libraries were screened with woodchuck-specific DNA probes to isolate the cDNA and gene clones for TNF, LT-alpha and LT-beta. The cDNAs for woodchuck TNF, LT-alpha and LT-beta code for proteins of 233, 205 and 310 amino acids respectively. The polypeptide encoded by each gene among woodchucks, humans and mice can differ: the human TNF, LT-alpha and LT-beta genes encode polypeptides of 233, 205 and 244 amino acids respectively, whereas the mouse TNF, LT-alpha and LT-beta genes encode polypeptides of 235, 202 and 306 amino acids respectively. In the woodchuck, there are four exons for TNF, four exons for LT-alpha and three exons for LT-beta. The RNA splicing patterns for TNF, LT-alpha and LT-beta genes are identical among woodchucks, humans and mice, except that the human LT-beta gene contains four exons. The woodchuck TNF gene promoter contains consensus sequences for binding of AP-1, AP-2, C/EBPbeta, CRE, Egr-1, Ets, NF-AT, NF-kappaB and SP-1 transcription factors. LT-alpha has AP-2, Ets, NF-kappaB, SP-1 and STAT binding sites, and LT-beta has Egr-1/SP-1, Ets and NF-kappaB binding sites. The bacterially expressed woodchuck TNF and LT-alpha proteins exhibited cytotoxic activities on both mouse L929B and woodchuck A2 cells in the presence of actinomycin D. The specific activities of TNF and LT-alpha were 2.62x10(8) units/mg and 2.22x10(3) units/mg respectively for L929B cells, and 1.05x10(9) units/mg and 3.56x10(4) units/mg respectively for A2 cells. However, only woodchuck TNF showed cytotoxic activity on human HepG2 cells, with a specific activity of 6.55x10(7) units/mg in the presence of actinomycin D. The data obtained from this study will be useful to future investigations of the TNF and LT antitumor and anti-viral activities, and their therapeutic potential in the woodchuck model for human hepatitis B virus (HBV).

Interaction of a novel red-region fluorescent probe, Nile blue, with DNA and its application to nucleic acids assay

A novel fluorimetric method was developed for the rapid determination of DNA and RNA based on their quenching effect on the cationic red-region fluorescent dye Nile Blue (NB). In the investigation of the interaction of NB with DNA by steady-state polarization measurements, thermal denaturing study, determination of absorption and fluorescence characteristics, salt effect study and electrophoresis experiments, the results supported the suggestion that NB served as an intercalator to the stack base pairs of nucleic acids. Further evidence showed that the quenching could be ascribed to the static quenching mode. A binding constant of about 10(6) M-1 and a binding site size of about three base pairs were obtained by spectral methods. Under optimum conditions, the calibration curves for the determination of calf thymus DNA (CT DNA) and yeast RNA were linear over the ranges 3.0 ng mL-1-2.0 micrograms mL-1 and 27 ng mL-1-10 micrograms mL-1, respectively. The detection limits were 3.0 ng mL-1 for CT DNA and 27 ng mL-1 for RNA. The relative standard deviation (n = 6) was within 2.1% in the middle of the linear range. Interferences from some interesting co-existing substances in the determination of DNA were also examined.

[The role of calcium in IAA-induced swelling of protoplasts isolated from hypocotyl of etiolated mung bean seedlings]

This paper studied on the role of calcium in IAA-induced swelling of protoplasts isolated from hypocotyl in etiolated mung bean (Phaseolus radiatus L.) seedlings. Protoplasts incubated in CaCl2-bearing medium without hormone maintained a constant volume and a consistent intensity of 45Ca2+ radioactivity. To treat with IAA, they began to swell and continually swelled to the maximum volume 30 minutes later (Fig. 2). However, the protoplasts could not swell when IAA was added into the medium without CaCl2 (Fig. 1). It was suggested that Ca2+ may be necessary for IAA to induce protoplast swelling. And also, IAA enabled the protoplasts to swell in less extent with K+, Zn2+, Ba2+ or Mg2+ instead of Ca2+ (Fig. 3). Radioisotope experiments showed that K+ influx increased when K+ replaced Ca2+ (Fig. 4), and water absorption plays a role in the swelling (Fig. 5). 45Ca2+ accumulation in protoplasts treated by IAA was much higher than that of control, and the time course of 45Ca2+ accumulation was similar to that of protoplasts swelling (Fig. 6). 45Ca2+ level and the swelling of protoplasts sharply declined when EGTA, verapamil or LaCl3 was added into the medium (Table 1, 2 and 3). These results indicated that Ca2+ may play an important role in IAA-induced swelling.

Evidence for the DNA binding and adduct formation of estrone and 17beta-estradiol after dimethyldioxirane activation

Estrogens, used widely from hormone replacement therapy to cancer treatment, are themselves carcinogenic, causing uterine and breast cancers. However, the mechanism of their carcinogenic action is still not known. Recently, we found that estrone (E1) and 17beta-estradiol (E2) could be activated by the versatile epoxide-forming oxidant dimethyldioxirane (DMDO), resulting in the inhibition of rat liver nuclear and nucleolar RNA synthesis in a dose-dependent manner in vitro. Since epoxidation is often required for the activation of chemical carcinogens, we proposed that estrogen epoxidation is the underlying mechanism for the initiation of estrogen carcinogenesis (Carcinogenesis 17 (1996) 1957-1961). It is known that initiation requires the binding of a carcinogen to DNA with the formation of DNA adducts. One of the critical tests of our hypothesis is therefore to determine whether E1 and E2 after activation are able to bind DNA. This paper reports that after DMDO activation, [3H]E1 and [3H]E2 were able to bind to both A-T and G-C containing DNAs. Furthermore. the formation of E1-DNA and E2-DNA adducts was detected by 32P-postlabeling analysis.

Design and fabrication of a diffractive phase element for wavelength demultiplexing and spatial focusing simultaneously

The design of a diffractive phase element (DPE) that simultaneously implements wavelength demultiplexing and focusing is carried out on the basis of the general theory of amplitude-phase retrieval. The designed DPE is fabricated with optical contact lithography. Three masks are needed to produce the surface-relief structure of the DPE with eight quantized levels in depths. Experiments demonstrate that the designed DPE can successfully implement both the functions of demultiplexing three different-wavelength beams and focusing each component at a predesignated position simultaneously. Experimental measurements are in good agreement with the results of numerical simulations.

Variations in cocaine self-administration by inbred rat strains under a progressive-ratio schedule

This study investigated the influence of genetics on extent of cocaine taking in rats that were self-administering cocaine under a progressive-ratio schedule. Fischer 344, ACI and Brown Norway rats were subjects because previous genetic studies on dopamine receptor loci have indicated that these are genetically divergent strains. All subjects were assessed for acquisition and stability of cocaine self-administration under a progressive ratio schedule. Subsequently, a dose-effect curve for cocaine self-administration was determined for each strain. Fischer 344 rats maintained a higher average breaking point than did the ACI or Brown Norway strains. In addition, dopamine receptor antagonists differentially reduced the ability of cocaine to serve as a reinforcer across the three strains. The D1-selective dopamine receptor antagonist, SCH 23390, and the D2/D3-selective dopamine receptor antagonist, eticlopride were significantly more effective in reducing the self-administration of cocaine in Brown Norway rats than for the other two strains. The results of this study demonstrate that genetic differences may play an important role in determining responding under progressive-ratio schedules for cocaine, possibly due to differences in the reinforcing efficacy of cocaine.

Natural populations of woodchuck hepatitis virus contain variant precore and core sequences including a premature stop codon in the epsilon motif

We have determined a consensus sequence and the type and the frequency of spontaneous sequence variations in the woodchuck hepatitis virus (WHV) precore gene and the 5' region of the core gene in 101 serum samples from 53 naturally WHV-infected woodchucks by polymerase chain reaction sequencing. Twenty of the 53 woodchucks were found to have variant sequences. Ten patterns of variant sequences were identified in these 20 animals. WHV sequences from 4 woodchucks had 1 nucleotide change, 3 had 2 nucleotide changes and 3 had 3 nucleotide changes. The nucleotide changes were not randomly distributed, but were limited to only 8 sites. Four sites were in the epsilon motif of the precore gene and four were in the 5' region of the core gene. Sixteen of the 53 (30%) woodchucks had precore sequence variants. All altered sites were analogous to previously described mutations in hepatitis B virus. There was a nucleotide change at nucleotide 2016 in codon 29 of the precore region that produced a stop codon in 4 animals. This site is analogous to a common hepatitis B virus e antigen mutation. The sequence from the initial blood samples from 3 of 4 animals with this stop codon producing variant appeared to be the consensus sequence; however, in later samples the variant occurred as a mixed infection with the consensus sequence. The mixed infections were chronic and the proportion of the variant sequence was maintained or increased in the course of infection. In the fourth animal only the variant was found and it persisted for over 14 months of infection. WHV appears to be a valuable model for the study of the structure and function of the hepadnavirus precore region.

Chronic d-amphetamine or methamphetamine produces cross-tolerance to the discriminative and reinforcing stimulus effects of cocaine

These experiments tested the hypothesis that chronic administration of d-amphetamine (d-A) or methamphetamine (METH) would produce cross-tolerance to the discriminative and/or reinforcing effects of cocaine. One group of rats (n = 20) was trained to detect cocaine (10.0 mg/kg; i.p.) from vehicle; cocaine (1.0-17.8 mg/kg) dose dependently substituted for the training dose. Chronic administration of d-A or METH (0.32, 1.0 and 3.2 mg/kg/12 hr for 7 days) resulted in cross-tolerance to the discriminative stimulus effects of cocaine. A second group of rats (n = 12) was implanted with indwelling jugular catheters and were trained to self-administer cocaine under a fixed-ratio 2 schedule of reinforcement. This group of rats also received chronic d-A or METH (0.32, 1.0 and 3.2 mg/kg/12 hr for 7 days. In this group, chronic administration of the highest dose of d-A and of METH (3.2 mg/kg) resulted in cross-tolerance to the self-administration of cocaine. A third group of rats (n = 15) was implanted with indwelling jugular catheters and were trained to self-administer cocaine under a progressive-ratio schedule of reinforcement. Chronic administration of d-A and METH (3.2 mg/kg/12 hr for 7 days) resulted in cross-tolerance to the self-administration of cocaine under this progressive-ratio schedule. The data obtained from these experiments demonstrate that chronic treatment with central nervous system stimulants of the amphetamine type (d-A or METH) produces cross-tolerance to both the discriminative and reinforcing effects of cocaine.

The 3'-5' exonuclease site of DNA polymerase III from gram-positive bacteria: definition of a novel motif structure

The primary structure of the 3'-5' exonuclease (Exo) site of the Gram+ bacterial DNA polymerase III (Pol III) was examined by site-directed mutagenesis of Bacillus subtilis Pol III (BsPol III). It was found to differ significantly from the conventional three-motif substructure established for the Exo site of DNA polymerase I of Escherichia coli (EcPol I) and the majority of other DNA polymerase-exonucleases. Motifs I and II were conventionally organized and anchored functionally by the predicted carboxylate residues. However, the conventional downstream motif, motif III, was replaced by motif III epsilon, a novel 55-amino-acid (aa) segment incorporating three essential aa (His565, Asp533 and Asp570) which are strictly conserved in three Gram+ Pol III and in the Ec Exo epsilon (epsilon). Despite its unique substructure, the Gram+ Pol III-specific Exo site was conventionally independent of Pol, the site of 2'-deoxyribonucleoside 5-triphosphate (dNTP) binding and polymerization. The entire Exo site, including motif III epsilon, could be deleted without profoundly affecting the enzyme's capacity to polymerize dNTPs. Conversely, Pol and all other sequences downstream of the Exo site could be deleted with little apparent effect on Exo activity. Whether the three essential aa within the unique motif III epsilon substructure participate in the conventional two-metal-ion mechanism elucidated for the model Exo site of EcPol I, remains to be established.

Characterization and overexpression of the gene encoding Staphylococcus aureus DNA polymerase III

The polC gene specifying DNA polymerase III (PolIII) of Staphylococcus aureus (Sa), was cloned with a novel strategy and found to contain a 4305-bp open reading frame (ORF) encoding a polypeptide of approx. 162 kDa. The 1435-codon ORF was engineered into an Escherichia coli (Ec) expression plasmid under the control of the lac promoter and its repressor. Derepression of Ec transformants carrying the recombinant (re-) vector generated high-level synthesis of active re-Sa PolIII. The re-PolIII was purified to > 98% homogeneity and was shown by N-terminal amino acid sequence analysis to be the bona fide product of the Sa polC ORF. The physical and catalytic properties of re-Sa PolIII and its responsiveness to inhibitors of the HPUra type were generally similar to those of Bacillus subtilis (Bs) PolIII. Comparative analysis of the primary structures of Sa PolIII, Bs PolIII and Mycoplasma pulmonis PolIII indicated strong conservation of essential catalytic domains and a novel zinc-finger motif. Comparison of the primary structures of Ec PolIII and these three Gram+ enzymes revealed a region of novel homology and reinforced the likelihood of a specific evolutionary relationship between PolIII of Gram+ and Gram- eubacteria. The polC gene mapped between omega 1074 [Tn551] and recA/ngr on the Sa NCTC 8325 genome.

Tolerance to the reinforcing effects of cocaine in a progressive ratio paradigm

This experiment used rats to test whether a regimen of chronic cocaine would produce tolerance to cocaine i.v. self-administration under a progressive ratio (PR) schedule of reinforcement. Under this PR schedule, an increasing number of responses was required to complete the ratio for each subsequent cocaine injection, and failure to complete the required ratio for the next injection within 1 h of the previous cocaine injection terminated the session. The number of injections taken in the session was termed the breaking point and used as the dependent variable. Rats were trained under this schedule until breaking point values were stable, after which cocaine dose-effect data were obtained: the breaking point increased as the dose of cocaine increased. Subsequently, rats were assigned to one of two groups for 7 days of chronic treatment: one group was infused with cocaine (18 mg/kg, given over 20 min once every 8 h) and the other group received 0.9% saline. Following termination of chronic treatment, cocaine dose-effect data were redetermined in both groups. Chronic cocaine treatment significantly decreased breaking point values across the entire dose-effect curve, although the effect was observed in only four of seven subjects. In contrast, chronic saline treatment produced no significant effect on the breaking point measures. Following a further 5 days of recovery from chronic treatment, cocaine dose-effect data were redetermined in both groups; these curves were essentially identical to those obtained before chronic treatments. These data support the hypothesis that tolerance occurs to the reinforcing effects of cocaine, as measured by a decrease in the breaking point, at least for a subset of animals.

Antitumor agents--CLI. Bis(helenalinyl)glutarate and bis(isoalantodiol-B)glutarate, potent inhibitors of human DNA topoisomerase II

Evaluation of a number of cytotoxic antitumor sesquiterpene lactones and their derivatives has led to the discovery of bis(helenalinyl)glutarate (4) and bis(isoalantodiol-B)glutarate (10) as potent inhibitors of human-derived topoisomerase II. Unlike etoposide, which inhibits by preventing the DNA rejoining process, compounds 4 and 10 inhibit topoisomerase II without causing DNA breakage. The structure-activity relationships of 4, 10, and related compounds are discussed.

Parameters of self-administration of cocaine in rats under a progressive-ratio schedule

Progressive-ratio (PR) schedules may provide a more direct measure of drug-reinforcing efficacy than the more traditionally used fixed-ratio schedules. Under a PR schedule, an increasing number of lever presses is required for the delivery of each successive reinforcer. However, there have been few studies of fundamental parameters of cocaine self-administration under a PR schedule. This study was undertaken to assess if PR responding using cocaine reinforcement in rats would: a) be acquired rapidly; b) be maintained on a stable baseline for long periods; and c) provide data on the effect of changing the dose of cocaine that are amenable to statistical analysis. In addition, the effects of pretreatments with SCH23390, a D1 receptor antagonist, or ondansetron, a 5-hydroxytryptamine3 (5-HT3) receptor antagonist, were tested against several doses of cocaine. Stable performance of PR cocaine self-administration (0.90 mg/kg) was acquired within 10 training sessions and was maintained for over 50 training sessions. Increasing the dose of cocaine from 0.10-2.70 mg/kg resulted in a directly related increase in a) the number of reinforcers obtained, b) the highest ratio completed, and c) the interreinforcer time (ISRT: time between each cocaine infusion). In terms of statistical analysis, the number of reinforcers obtained was found to be preferable to the highest ratio completed as a measure of breakpoint. Pretreatment with SCH23390 significantly reduced the breakpoint; this reduction was not due to a motor-incapacitating effect of SCH23390 because the ISRT showed a tendency to be shortened by SCH23390. Pretreatment with ondansetron failed to significantly affect either the number of reinforcers obtained or the ISRT. These results show that rats can readily acquire the task of self-administration of cocaine under a PR schedule and maintain a stable baseline for an extended period. Further, a PR schedule appears to be suitable for the study of pharmacological treatments that might affect cocaine self-administration. Simultaneous monitoring of the breakpoint and of the ISRT determines if a decrease in the breakpoint is the result of a motor-incapacitating side effect of the pretreatment.

[Experimental studies on the symptom-complex mechanism of pi man zao shi of dachengqi decoction]

Experiments have shown that Dachengqi Decoction can inhibit the activity of G-germs which commonly grow in the intestinal tract, inactivate the endotoxin directly in vitro, reduce the amplitude of fever caused by endotoxin injected intravenously, promote the gastric secretion and gastric retaining in rats, and increase the level of glycogen in liver. It also has some other effects. All these actions contribute to the explanation on the efficacy of Dachengqi Decoction to purge off the internal heat.

Effective hybrid processor to compute image moments for pattern recognition

A hybrid optical-digital processor is presented for computing the invariant moments of images in real time, which consists of a holographic mask, two lenses, a charge-coupled-device detector, and a microcomputer. The processor is tested by inputting some roman letters, and the produced results show that the invariant moments of a letter are approximately independent of shift and rotation and that the moments are distinct with different letters.

Modulation by dietary vitamin E of I-compounds (putative indigenous DNA modifications) in rat liver and kidney

I(indigenous)-compounds are age-related, carcinogen adduct-like, putative indigenous DNA modifications detectable by 32P-postlabeling assay in untreated animals. To investigate the origins of these DNA derivatives, we examined the effects of dietary vitamin E, a natural antioxidant, on I-compounds of rat liver and kidney DNA. Weanling female Sprague-Dawley rats were fed Draper's diets containing 0, 100, 1000, or 10,000 mg/kg alpha-tocopheryl acetate for 6 mo. The DNA from four individual rats of each group was analyzed by a nuclease P1-enhanced version of the 32P-postlabeling assay for DNA adducts. The amount of vitamin E in the liver was measured by high performance liquid chromatography. Rats fed vitamin E-deficient diet (0 mg/kg) showed identical profiles and similar levels of I-compounds as those fed the 100 mg/kg diet. Most I-spots were significantly intensified and one tissue-specific extra spot was found in both liver and kidney DNA of rats fed the 1000 or 10,000 mg/kg vitamin E diet. However, one of the five major I-spots detected in the kidney was weaker in the 1000 and 10,000 mg/kg groups than in the 0 and 100 mg/kg groups. These results show that formation of most I-compounds was not affected by vitamin E-deficient diet, and that long-term feeding of diet containing high levels of vitamin E may cause metabolic alterations leading to an increased formation of DNA-reactive (potentially mutagenic or carcinogenic) electrophiles.

Species and tissue specificities of I-compounds as contrasted with carcinogen adducts in liver, kidney and skin DNA of Sprague-Dawley rats, ICR mice and Syrian hamsters

I-compounds are age-related bulky DNA modifications that are detected in untreated animals by 32P-postlabeling. To characterize their properties, I-compounds were compared with carcinogen-DNA adducts in liver, kidney and skin of three rodent species. Weanling female Sprague-Dawley rats, ICR mice and Syrian hamsters were fed Teklad LM485 chow diet for 3 months and raised concurrently and strictly under the same environmental conditions. Animals of each species were treated topically with 24 mumol/kg dibenz[a,j]acridine per day for 3 days, then by gavage once with a mixture of safrole and 7,12-dimethylbenz[a]anthracene (60 and 80 mumol/kg respectively), or with one of the individual carcinogens. Liver, kidney and skin DNA from carcinogen-exposed (24 h after treatment) and unexposed animals was analyzed by the monophosphate version of the 32P-postlabeling assay. While each of the three carcinogens produced qualitatively identical major adduct patterns in all samples examined, I-compounds in untreated animals showed distinct species- and tissue-dependent profiles. Rats displayed the highest I-compound levels but the lowest adduct levels in both liver and kidney among the three species. These findings demonstrate fundamental differences between I-compounds and carcinogen-DNA adducts, and support the hypothesis that I-compound formation is primarily related to species-specific, i.e. genetically determined, normal metabolic activities rather than exposure to environmental genotoxic carcinogens.

Persistent reduction of indigenous DNA modification (I-compound) levels in liver DNA from male Fischer rats fed choline-devoid diet and in DNA of resulting neoplasms

Reduced levels of putative indigenous DNA modifications (I-compounds) in liver DNA of male Fischer 344 rats fed a hepatocarcinogenic choline-devoid (CD) diet for up to 7 mo have been previously reported. To investigate the persistence of this effect and possible relationships between I-compounds and hepatocarcinogenesis, liver DNA modifications of tumor-free male rats fed a CD diet for 3, 6, 9, or 12 mo, followed by a choline-supplemented (CS) diet to 16 mo, were compared with those in rats fed exclusively the CD or CS diet for 16 mo by a 32P-postlabeling assay. In addition, DNA from nontumorous and tumorous tissues of rats fed the CD diet similarly for 12 or 16 mo was analyzed. It was found that total I-compound levels in male rats consecutively fed CD and CS diets for various lengths of time were similar to those in rats fed the CD diet only and significantly lower than those in rats fed the CS diet only. I-compound levels of nontumorous regions from tumor-bearing livers were 73% of those in tumor-free livers from the same treatment group. I-compound levels were further reduced, some to undetectable levels, in tumor tissues and exhibited an inverse relationship with tumor incidence. The patterns and levels of I-compounds in liver DNA of CD diet-fed female rats, which were not susceptible to CD diet-induced hepatocarcinogenesis, on the other hand, were not significantly different from those of controls. Thus, reduction of I-compound levels by feeding a CD diet lasted for many months after changing from the CD to the CS diet. Whether this persistent DNA alteration contributes to carcinogenesis remains to be determined.

Association between diet and age-related DNA modifications (I-compounds) in rat liver and kidney

Mammalian tissue DNA has recently been found, by 32P-postlabeling, to contain complex profiles of age-dependent and tissue-specific bulky carcinogen adduct-like modifications, which have been termed I-compounds since they appeared to arise indigenously, in the absence of exposure to exogenous carcinogens. I-compounds are presumably formed by reaction of metabolically produced, as yet unidentified, electrophiles with DNA. In order to shed light on the origin of I-compounds, we have examined whether diet affects the levels and profiles of I-compounds. Weanling female Sprague-Dawley rats were provided with either one of three natural ingredient diets (rodent chows) or a purified diet (AIN-76A) for up to 6 months. Liver and kidney DNAs were analyzed after 0, 3, and 6 months of feeding, by a nuclease P1-enhanced 32P-postlabeling assay. Rats fed natural ingredient diets showed a greater complexity and 2.5-6.4-fold higher levels of I-compounds in the DNA of both tissues than rats fed purified diet. In addition, less marked qualitative and quantitative differences were noted among rats fed different chow diets. Three classes of I-compounds were identified: class A, I-spots common to both kinds of diet; class B, chow-specific spots; and class C, AIN-76A-specific spots. Liver and kidney shared some I-compounds, mostly belonging to class A, but there were also tissue-specific spots. These observations indicate a novel intimate link between diet and DNA modifications and are consistent with the hypothesis that the formation of I-compounds proceeds via normal metabolism of nutrients and other natural dietary components, leading to the production of small amounts of DNA-reactive electrophiles. Because of their DNA adduct-like character, I-compounds may play a critical role at the interface between nutrition and cancer.

Age-related DNA modifications (I-compounds): modulation by physiological and pathological processes

I-compounds are covalent DNA modifications that can be detected and measured by 32P-postlabeling assay because of their DNA-adduct like properties. They accumulate in an age-dependent, highly reproducible manner in tissue DNA of untreated animals in the absence of exogenous carcinogens and, therefore, appear to arise via the interaction of DNA with endogenous reactants formed in the course of normal metabolism. Chromatographically, they exhibit a wide range of polarities, indicative of structural diversity. In addition to age-dependent increases, I-compound profiles exhibit prominent species-, sex-, tissue- and diet-dependent qualitative and quantitative differences. Natural-ingredient (chow) diets produce qualitative differences as well as substantially higher I-compound levels in rat liver and kidney, when compared with purified diets. Modified purified diets containing high carbohydrate, protein, or fat concentrations further modulate I-compound profiles. During liver regeneration, I-compounds behave like DNA adducts rather than m5 C in that their levels are not quickly restored. Treatment of rats with the hepatocarcinogens 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), CCl4, and peroxisome proliferators as well as with a choline-devoid hepatocarcinogenic diet depressed the age-related increases of I-compound levels in liver, the target organ. Additional 32P-labeled derivatives were observed only with the peroxisome proliferators and presumably represent DNA adducts of exogenous origin. No I-compounds were detected in a series of Morris hepatomas with different degrees of differentiation. Thus, loss of I-compounds may be associated with altered gene expression/dedifferentiation. On the other hand, the age-dependent accumulation of I-compounds and their adduct-like character suggest potential relations to aging-associated dysdifferentiation and initiation of cancer. Structural complexity indicates different biological roles of I-compounds.

Strain differences of I-compounds in relation to organ sites of spontaneous tumorigenesis and non-neoplastic renal disease in mice

Possible associations between the patterns and levels of I-compounds (putative endogenous, age-dependent, adduct-like DNA derivatives) and the incidence of spontaneous tumors and renal diseases in mice were investigated by 32P-postlabeling assay. Liver, lung and kidney DNAs of 8-10 month old inbred male mice of strains C57BL, C3H, CBA, A and RFM were examined. It was found that liver DNA of the C3H mouse, known to develop a high incidence of spontaneous hepatomas, and lung DNA of the A mouse, known to have a high incidence of spontaneous lung tumors, contained smaller numbers and significantly lower total levels of I-compounds as compared with the resistant C57BL mouse. Kidney DNA of C57BL, C3H and A mice presented significantly higher levels of I-compounds compared with those of CBA and RFM mice, both of which are known for exceptionally high incidences of spontaneous renal diseases. Total kidney I-compound levels in CBA and RFM mice were only 30-40% of those found in C3H, A and C57BL. Reduced I-compound levels observed in the three organs thus tended to be associated with spontaneous tumorigenesis and degenerative disease in susceptible strains, suggesting that I-compounds may be important for normal gene transcription and DNA replication. On the other hand, some of these DNA derivatives may, as adduct-like premutagenic lesions, contribute to spontaneous tumorigenesis. This was suggested by the finding that CBA mice which exhibit moderate spontaneous hepatoma incidence, had higher levels of certain I-compounds in their liver DNA although the total levels were not significantly different compared with those in C57BL mice. The observations of the present study suggest that (i) the patterns and levels of I-compounds are genetically determined and (ii) lack or excess of these DNA modifications may result in adverse health effects; however, this may not always be the case, for example, if modulating factors exist which compensate for I-compound deficiency.

Acute and long-term effects of carbon tetrachloride on DNA modifications (I-compounds) in male mouse liver

I-compounds are recently discovered species and tissue dependent covalent DNA modifications which are detectable by the 32P-postlabeling assay for DNA adducts and tend to increase with the animal's age. The effects of the hepatocarcinogen carbon tetrachloride (CCl4) on hepatic I-compounds were studied in 10-12-month-old male ICR mice using the 32P-postlabeling assay. CCl4 was dissolved in corn oil (20%, v/v) and intraperitoneally (i.p.) injected in doses of 0.75 ml/kg (0.375 ml/100 g body weight, 20% CCl4 in corn oil) while control mice received corn oil only (0.375 ml/100 g body wt). Twenty-four h after a single injection of CCl4, the intensity of non-polar I-spots in liver DNA was significantly increased as compared with corn oil treated controls, while the level of one polar I-compound was reduced at 24 h. DNA synthesis (as indicated by [3H]thymidine incorporation) was not significantly affected at 24 h after a single dose of CCl4. To study the long-term effects of CCl4, five groups of mice were given two consecutive weekly injections of 0.75 ml/kg CCl4 (as above) and were sacrificed 1, 4, 8, 12 and 22 weeks after the second treatment. In these groups the total liver I-compound levels were reduced to 17.3-49.0% compared with corresponding controls. The maximum decline was observed at 4 weeks (17.3% of control). Comparison of thymidine incorporation showed no significant increase between control and treated liver DNAs at 1, 4 and 8 weeks after CCl4, suggesting that the decrease in I-compound levels was probably not a secondary effect of increased DNA synthesis during postnecrotic proliferation. Even though there was a trend of recovery between 8 and 22 weeks, I-compound levels still remained significantly lower at 22 weeks (49.0%). Since I-compounds appear to be normal DNA modifications, the results suggest that persistent reduction of I-compound levels contributes to the hepatocarcinogenic effect of CCl4.

Antitumor agents. 100. Inhibition of human DNA topoisomerase II by cytotoxic ether and ester derivatives of podophyllotoxin and alpha-peltatin

A principal mechanism of action of the clinical antitumor drugs etoposide (1) and teniposide (2) is the inhibition of catalytic activity of type II DNA topoisomerase and concurrent enzyme-mediated production of lethal DNA strand breaks. Substitution of the glycosidic moiety of 1 or 2 by ester and ethers, as well as the esterification and etherification of alpha-peltatin (4) including its glucosidic ethylidene and thenylidene cyclic acetals (25 and 26), has afforded compounds of much less activity than that of 1. The in vitro cytotoxicity (KB) appears to have no correlation with the inhibitory activity of the human DNA topoisomerase II.

Combined modalities of resistance in etoposide-resistant human KB cell lines

The alkaloid derivative 4'-demethylepipodophyllotoxin 9-(4,6-O-ethylidene)-beta-D-glucopyranoside (etoposide, VP-16) is believed to exert cytotoxicity by causing double-stranded DNA breaks through interruption of the breaking-resealing reaction of topoisomerase II (topo II). Thus it was conceivable that cells could become resistant to VP-16 by a decrease in topo II enzyme level, since this would lead to fewer DNA breaks. As well, given the structure of VP-16, it was also possible that a pleiotropic mechanism of resistance could decrease sensitivity to this drug. To study these possibilities, a series of VP-16-resistant human KB cell lines was established by stepwise selection. The concentrations of VP-16 required to inhibit cell proliferation by 50% in the parent line and KB/1c, KB/7d, KB/20a, and KB/40a lines were, respectively, 0.16, 4.7, 24, 31, and 47 microM. These cell lines expressed cross-resistance to 4'-(9-acridinylamino)methanesulfon-m-anisidide, doxorubicin, vincristine, and methotrexate, although the pattern of relative drug sensitivity was quite different from that of pleiotropic resistant cell lines reported elsewhere. The resistance to vincristine and methotrexate did not increase above the level of the KB/1c cells, and resistance to VP-16, doxorubicin, and especially vincristine was unstable in VP-16-resistant cells cultured in the absence of drug. Although the drug resistance marker Mr 180,000 glycoprotein could not be detected in any of our cell lines, cellular accumulation of [3H]VP-16 was reduced 50-75% in the resistant lines compared with parent KB. With increasing VP-16 resistance, the level of topo II protein, detected by antibody staining, decreased at each step of selection, concomitant with a general decrease in topo II unknotting activity. Sensitivity of the topo II unknotting assay to inhibition by VP-16 was the same for the parent and all resistant cell lines. The level of topo I activity and enzyme increased slightly in the resistant cells. Thus, these cell lines are resistant to VP-16 by virtue of at least two mechanisms: (a) reduced levels of topo II, which confers cross-resistance to other compounds which are topo II-dependent cytotoxic agents; and (b) reduced accumulation of drug, which is likely also responsible for vincristine and methotrexate resistance. However, the possible existence of other mechanisms of resistance cannot be ruled out.

Optical Walsh-Hadamard transform for orders 32 and 64

A coherent optical system composed of a holographic mask and two Fourier lenses is described for performing an arbitrary linear transform. A set of equations for determining the amplitude-phase distribution of the mask is given. As a specific transform, the Walsh-Hadamard transform for orders 32 and 64 is optically made in 1-D space.

Preliminary approach to the diagnosis of byssinosis

The prevalence of byssinosis was studied in two cotton mills by a standardized questionnaire and pulmonary function measurements (forced expiratory volume in 1 second; FEV1). In mill A, the dust level was high (57-159 mg/m3). Among 90 participants, 80 were interviewed twice at an interval of 4 months, and disagreement on actual presence or absence of byssinosis was 7.5 percent. Twenty out of ninety workers had complaints of Monday symptoms and the prevalence was 22.2 percent. In mill B, the dust control (6.8 mg/m3) was relatively good. Among 173 participants from the carding room, two had complaints of Monday symptoms and the prevalence was 1.2 percent. A significant correlation was found between duration of employment and prevalence of byssinosis in mill A. FEV1 was measured in 9 byssinotics, 29 nonbyssinotics, and 30 controls before and after work on Mondays and Wednesdays. A significant decrease of 177 ml on average (7.8%) was found in byssinotics after work on Monday, whereas in nonbyssinotics, the decrease of FEV1 was nonsignificant. In controls, a slight increase in FEV1 after work was observed.