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Biomedical subjects

R Waters

Publications and source records attributed to R Waters.

At least 55 records · Page 3Linked to original sources
PubMed1996

Effects of erythrocyte infusion on VO2max at high altitude.

This study investigated whether autologous erythrocyte infusion would ameliorate the decrement in maximal O2 uptake (VO2max) experienced by lowlanders when they ascend to high altitude. VO2max was measured in 16 men (treadmill running) at sea level (SL) and on the 1st (HA1) and 9th (HA9) days of high-altitude (4,300 m) residence. After VO2max was measured at SL, subjects were divided into two matched groups (n = 8). Twenty-four hours before ascent to high altitude, the experimental group received a 700-ml infusion of autologous erythrocytes and saline (42% hematocrit), whereas the control group received only saline. The VO2max of erythrocyte-infused [54 +/- 1 (SE) ml.kg-1.min-1] and control subjects (52 +/- 2 ml.kg-1.min-1) did not differ at SL before infusion. The decrement in VO2max on HA1 did not differ between groups, averaging 26% overall, despite higher (P < 0.01) arterial hematocrit, hemoglobin concentration, and arterial O2 content in the erythrocyte-infused subjects. By HA9, there were no longer any differences in hematocrit, hemoglobin concentration, or arterial O2 content between groups. No change in VO2max occurred between HA1 and HA9 for either group. Thus, despite increasing arterial O2-carrying capacity, autologous erythrocyte infusion did not ameliorate the decrement in VO2max at 4,300-m altitude.

Acclimatization↗
PubMed1995

Development of a human biomonitoring assay using buccal mucosa: comparison of smoking-related DNA adducts in mucosa versus biopsies.

The aim of this study was to determine whether buccal mucosa would provide an alternate source of tissue for human biomonitoring. Samples of clinically normal oral biopsies were excised, and buccal mucosa were scraped or brushed from patients while they were undergoing surgery for the excision of intra-oral squamous cell carcinoma. Extracted DNA was 32P-postlabeled using the butanol enhancement method, and DNA adduct levels were quantified to compare the accuracy of adduct detection in buccal mucosa versus oral biopsies. For both tissues, tobacco smokers were found to have statistically significant higher levels of DNA damage than samples obtained from nonsmokers (P < 0.001). Mean relative adduct labeling in smokers was very similar for oral biopsies (6.16 x 10(-7)) and buccal mucosa (6.73 x 10(-7)). Likewise, mean relative adduct labeling values for nonsmokers were comparable in the two tissues (1.66 x 10(-7) for biopsies and 2.1 x 10(-7) for mucosa). Overall, an excellent correlation (r = 0.79; n = 32) was obtained between adduct levels in biopsies and mucosa for all classes of patient. These data indicate that buccal mucosa provides an additional tissue for monitoring human exposure to environmental genotoxins. The tissue is obtained rapidly in a noninvasive fashion when harvested by brushing. It can clearly be used to study components in cigarette smoke which cause DNA damage, and it is on the major route of exposure to many environmental genotoxins.

Autoradiography↗
PubMed1994

DNA damage induced by the environmental carcinogen butadiene: identification of a diepoxybutane-adenine adduct and its detection by 32P-postlabelling.

To date only a few studies have been undertaken on DNA adducts formed by epoxybutene (EB) and diepoxybutane (DEB), the two active metabolites of 1,3-butadiene. Our interests have focused on further investigating DNA alkylation by the two epoxides, especially in relation to the development of a method for human biomonitoring. Here, following the reaction of deoxyadenosine monophosphate and poly(dA-dT)(dA-dT) with DEB and subsequent HPLC, we have identified an adenine adduct. MS analyses indicate the structure of an adenine adducted by DEB at the N6 position. A HPLC/32P-postlabelling method was developed for its measurement in DNA samples and the adduct was detected in calf thymus DNA and DNA from Chinese hamster ovary cells exposed to DEB. The 100% labelling efficiency during postlabelling, the amount of the adduct and its elution before the normal nucleotides during HPLC suggest it could be a suitable indicator of BUT exposure.

Adamantane↗
PubMed1994

Single-stage reconstruction of key pinch and extension of the elbow in tetraplegic patients.

The results in ten arms of nine patients who had post-traumatic tetraplegia at the fifth or sixth cervical level were reviewed after combined transfer of the brachioradialis to the flexor pollicis longus and of the posterior part of the deltoid to the triceps tendon to restore key pinch and extension of the elbow. The average age of the patients was twenty-nine years, the average time from the injury to the operation was five years, and the average duration of follow-up was thirty-one months. Key pinch improved from essentially none preoperatively to an average of 2.0 pounds (0.9 kilogram) postoperatively: an average of 3.0 pounds (1.4 kilograms) for the patients who had tetraplegia at the sixth cervical level and an average of 0.9 pound (0.4 kilogram) for those who had tetraplegia at the fifth cervical level. Key pinch was favorably influenced by extension of the wrist, while the position of the elbow had no effect. Maximum active extension of the elbow against gravity was within 20 degrees of full extension in eight of the ten arms. There was an improvement in the performance of activities of daily living, including wheelchair use, and most of the patients discontinued use of special equipment for the upper extremity. The results of this study, when compared with those of each procedure performed separately, suggest that a combination of the operations improves function of the upper extremity and shortens the duration of dependence postoperatively.

Activities of Daily Living↗
PubMed1993

Detection of DNA adducts in human oral tissue: correlation of adduct levels with tobacco smoking and differential enhancement of adducts using the butanol extraction and nuclease P1 versions of 32P postlabeling.

Samples of clinically normal oral tissue were obtained from patients undergoing surgery for intraoral squamous cell carcinoma. DNA was extracted from samples obtained from 20 tobacco smokers, four exsmokers, and nine nonsmokers and analyzed for the presence of aromatic DNA adducts using two distinct modifications of the 32P postlabeling assay. 32P postlabeling following butanol extraction enhancement revealed a much wider range and substantially higher levels of DNA adducts than obtained following nuclease P1 enrichment. Adduct levels in smokers, exsmokers, and nonsmokers were 1133 +/- 354, 785 +/- 251, and 660 +/- 317 amol/microgram of DNA (+/- SD), respectively. The elevation of adduct levels in smokers compared with either nonsmokers or non- and exsmokers combined is statistically significant (P < 0.005). These observations are consistent with epidemiological evidence linking tobacco smoking with oral cancer. The differential enhancement of DNA adducts with the two 32P postlabeling protocols indicate that aromatic amines and nitroaromatics may be important sources of the DNA adducts detected in human oral tissue.

Adolescent↗
PubMed1993

Inducible removal of UV-induced pyrimidine dimers from transcriptionally active and inactive genes of Saccharomyces cerevisiae.

The prior UV irradiation of alpha haploid Saccharomyces cerevisiae with a UV dose of 25 J/m2 substantially increases the repairability of damage subsequently induced by a UV dose of 70 J/m2 given 1 h after the first irradiation. This enhancement of repair is seen at both the MAT alpha and HML alpha loci, which are, respectively, transcriptionally active and inactive in alpha haploid cells. The presence in the medium of the protein synthesis inhibitor, cycloheximide in the period between the two irradiations eliminated this effect. Enhanced repair still occurred if cycloheximide was present only after the final UV irradiation. This indicated that the first result is not due to cycloheximide merely blocking the synthesis of repair enzymes associated with a hypothetical rapid turnover of such molecules. The enhanced repairability is not the result of changes in chromatin accessibility without protein synthesis, merely caused by the repair of the damage induced by the prior irradiation. The data clearly show that a UV-inducible removal of pyrimidine dimers has occurred which involves the synthesis of new proteins. The genes known to possess inducible promoters, and which are involved in excision are RAD2, RAD7, RAD16 and RAD23. Studies with the rad7 and rad16 mutants which are defective in the ability to repair HML alpha and proficient in the repair of MAT alpha showed that in rad7, preirradiation enhanced the repair at MAT alpha, whereas in rad16 this increased repair of MAT alpha was absent. The preirradiation did not modify the inability to repair HML alpha in either strain. Thus RAD16 has a role in this inducible repair.(ABSTRACT TRUNCATED AT 250 WORDS)

Blotting, Southern↗
PubMed1993

Cellular and chromosomal hypersensitivity to DNA crosslinking agents and topoisomerase inhibitors in the radiosensitive Chinese hamster irs mutants: phenotypic similarities to ataxia telangiectasia and Fanconi's anaemia cells.

The mutants irs1, irs2 and irs3 were previously isolated from the Chinese hamster line V79-4 on the basis of their hypersensitivity (2-3-fold) to cell inactivation by X-rays. Here the cross-sensitivities of the irs mutants to an array of chemical mutagens and topoisomerase inhibitors was determined in a differential cytotoxicity assay. Irs2 showed moderate hypersensitivity (2-3-fold) to simple alkylating agents and oxidative mutagens but was most sensitive (8-fold) to the topisomerase I inhibitor camptothecin. In contrast irs2 showed little or no increased sensitivity to four topoisomerase II inhibitors. Irs3 proved to be particularly hypersensitive to DNA crosslinking agents (5-15-fold) such as 1,3-butadiene diepoxide and mitomycin C. Irs1 was hypersensitive (3-fold or greater) to simple alkylating agents, oxidative mutagens and topoisomerase I and II inhibitors and exhibited extreme sensitivity (20-100-fold) to DNA crosslinking agents. The cellular hypersensitivities of irs2 and irs3 were reflected at the level of the chromosome. Camptothecin induced chromosomal aberrations in irs2 consisted almost exclusively of chromatid deletions and exchanges, whilst in irs3 1,3 butadiene diepoxide induced a 50-fold increase in chromatid exchanges compared with V79-4. The nature of irs2's camptothecin hypersensitivity was investigated. Analysis of the protein associated DNA single strand breaks produced by camptothecin indicated that there was no difference between V79-4 and irs2 in either the number of breaks induced or in the rate of their reversal following drug removal. In addition, levels of topoisomerase I activity in V79-4 and irs2 were indistinguishable. The data presented suggest that irs3 is likely to be defective in some aspect of DNA cross-link removal and irs2, whilst showing no gross defect in DNA strand break repair may fail to correctly respond to or repair certain types of strand breaks, possibly those associated with replicating DNA. The phenotypes of irs2 and irs3 respectively show similarities to those of cultured cells from the syndromes ataxia telangiectasia and Fanconi's anaemia.

4-Nitroquinoline-1-oxide↗
PubMed1993

Biomonitoring of exposure to 1,3-butadiene: detection by high-performance liquid chromatography and 32P-postlabelling of an adenine adduct formed by diepoxybutane.

1,2-Epoxy-3-butene and 1,2:3,4-diepoxybutane, the two oxidative metabolites of 1,3-butadiene, are considered to be involved in some of the carcinogenicity of the parent compound. Diepoxybutane is a bifunctional alkylating agent and reacts with DNA to form monoadducts and cross-links. We investigated DNA alkylation after exposure to diepoxybutane in order to develop a method for human biomonitoring. After reacting dAMP and then poly(dA-dT) (dA-dT) with diepoxybutane, we identified a major adenine adduct. Preliminary mass spectrometry indicated an adenine adducted by diepoxybutane at the N6 position. A high-performance liquid chromatography/32P-postlabelling method was developed, and the adduct was detected in calf thymus DNA and in DNA from Chinese hamster cells after exposure to diepoxybutane. The labelling efficiency, the amount of the adduct and its stability suggest that it could be a suitable indicator of exposure to butadiene.

Adenine↗
PubMed1993

Detection by HPLC-32P-postlabelling of DNA adducts formed after exposure to epoxybutene and diepoxybutane.

We have developed an HPLC-32P-postlabelling procedure to detect DNA adducts formed by epoxybutene and diepoxybutane. The method exploits the interaction of the two epoxides with deoxynucleotides and polydeoxynucleotides to optimize the HPLC enrichment of adducted nucleotides before 32P-postlabelling. Using this approach, a number of guanine adducts were identified after the exposure of dGMP, poly(dG-dC) or calf thymus DNA to epoxybutene and diepoxybutane, and a major adenine adduct was identified in poly(dA-dT) and calf thymus DNA exposed to diepoxybutane.

Animals↗
PubMed1993

32P-postlabelling analysis of human tissues and its potential use for biomonitoring.

Samples of clinically normal oral tissue were obtained from 17 tobacco smokers and 7 non- or ex-smokers undergoing surgery for intra-oral squamous cell carcinoma. Isolated DNA was analysed for the presence of aromatic DNA adducts using the 32P-postlabelling technique with adduct enhancement by either butanol extraction or nuclease P1 enrichment. DNA adduction detected following butanol extraction was more diverse and at a higher level than obtained with the P1 method. Adduct levels in the smokers and non- or ex-smokers were 1163 +/- 375 and 774 +/- 318 amol/micrograms, respectively. This difference is statistically significant (p < 0.05). The differential enhancement of adducts with the two protocols suggested that arylamines may be the source of at least a proportion of the DNA adduction detected. These data indicate that oral tissues are likely to be a suitable source of material for human biomonitoring and furthermore they highlight the importance of utilizing more than one enhancement procedure when examining DNA adduction induced by complex mixtures such as tobacco smoke or those encountered at industrial plants.

Butanols↗
PubMed1992

The repair of large DNA adducts in mammalian cells.

This paper describes experiments involving the measurement of DNA damage and repair after treatment with 4-nitroquinoline 1-oxide (4NQO) or aflatoxin B1 (AFB1) epoxide in a number of mammalian cell cultures primarily associated with defects in the excision repair of UV-induced DNA damage. The results with transformed derivatives of XP cells belonging to different complementation groups showed that the extent of repair of 4NQO adducts at the N2 or C8 of guanosine did not correlate to the extent of repair reported by others after UV-irradiation. An examination of 4NQO repair in rodent UV-sensitive cell lines from different ERCC groups indicated that again there was little correlation between the extent of 4NQO and UV repair. However, regardless of complementation group those mutants that were defective in the repair of pyrimidine dimers and 6,4-photoproducts did exhibit a reduced ability to repair the 4NQO N2 guanosine adduct, whereas those mutants defective in pyrimidine dimer repair alone were able to repair this lesion as normal. In all of these cell lines there was a normal capacity to repair the 4NQO C8 guanosine adduct. Less extensive experiments involving AFB1 epoxide showed an XPC-transformed cell line was able to repair 40% of lesions after 6 h, whereas only 20% of repair is seen after UV. The rodent mutant V-C4 which belongs to the same ionising radiation group as irs2, was partially defective in repairing AFB1-induced damage. These experiments highlight the fact that although there are many commonalities between the repair of UV damages and lesions classed as large DNA adducts differences clearly exist, the most striking example here being the repair of the C8 guanosine 4NQO adduct which rarely correlates with a defect in UV repair.

4-Nitroquinoline-1-oxide↗
PubMed1992

Sensitivity and single-strand DNA break repair in Chinese hamster mutants exposed to the carcinogen aflatoxin B1 epoxide and its dichloride model.

Aflatoxin B1 (AFB1) is a potent carcinogen and mutagen. It requires metabolic activation to be converted to the DNA-binding product aflatoxin B1 epoxide (AFB1-epoxide). A model of this epoxide is aflatoxin B1 dichloride (AFB1Cl2). Both react at the N7 position of guanine to form large adducts. The major adduct formed can either be rapidly removed to leave an apurinic site or can undergo ring opening of the imidazole ring to form a chemically stable adduct. A number of Chinese hamster DNA repair-deficient mutants have been screened for their sensitivity to AFB1-epoxide and AFB1Cl2. Some of the mutants screened belong to different UV complementation groups. Human genes involved in nucleotide excision-repair correct deficiencies found in these complementation groups. The mutants which were found to be most sensitive to AFB1 (V-C4 and V-H1) were further investigated. Alkaline elution was used to measure AFB1-induced DNA single-strand break repair in the mutants. V-H1 repaired completely in 24 h whereas V-C4 displayed only partial repair.

Aflatoxin B1↗
PubMed1992

Radical axillary dissection in the staging and treatment of breast cancer.

The results of 237 radical axillary dissections undertaken by one surgeon in patients with breast cancer were reviewed to evaluate the role of this procedure in staging and treatment. The accuracy of physical examination in detecting axillary metastases was 68%. With a policy of enforced shoulder immobilisation for 10 days postoperatively, the incidence of postoperative wound complications was 8%. There have been three axillary recurrences during a median follow-up period of 44 months (range 6-97 months). Late complications were assessed in 50 patients followed up for greater than 12 months. While eight patients complained of constant swelling of the arm, only three had a difference in arm circumference of greater than 3 cm and only one had persistent limitation of shoulder abduction. Radical axillary dissection ensures accurate clinical staging and provides excellent local control with few complications and without the need for axillary irradiation.

Axilla↗
PubMed1991

32P-postlabelling analysis and micronuclei induction in primary Chinese hamster lung cells exposed to tobacco particulate matter.

The genotoxicity of tobacco particulate matter (TPM) derived from a low-tar, low-nicotine cigarette has been examined by measuring micronucleus induction in a primary pulmonary cell line, both in the absence and presence of an exogenous source of metabolic activation. In an attempt to correlate the cytogenetic damage observed with DNA adduct formation, DNA extracted from TPM-treated cells has been analysed with two different modifications of the 32P-postlabelling assay. The results from the 32P-postlabelling analysis taken together with the pattern of micronucleus induction provide strong evidence that bioreactivated aromatic carcinogens, such as benzo[a]pyrene, are unlikely to be responsible for the TPM-induced cytogenetic damage observed in cultured mammalian cells.

Animals↗
PubMed1991

The repair of 4-nitroquinoline-1-oxide induced DNA adducts in hypersensitive Chinese hamster mutants: lack of repair of UV induced (6-4) photoproduct correlates with reduced repair of adducts at the N2 of guanosine.

UV sensitive Chinese hamster mutants belonging to ERCC groups 1, 2 and 6 together with one cross-link- and one X-ray-sensitive mutant have been examined for sensitivity to 4-nitroquinoline-1-oxide (4NQO) and the ability to repair 4NQO adducts at the N2 and C8 of guanosine. Despite the fact that all of the mutants examined were hyper-sensitive to 4NQO there was little difference between the mutants V-H1, V-H4, V-C4 and UV61 and the parental cell lines as regards the ability to remove these lesions from bulk DNA. The UV5 and UV20 mutants were both defective in the ability to remove N2 guanosine adducts yet repaired the C8 guanine adduct as normal. The fact that the mutants V-H1, V-H4, V-C4 and UV61 are 4NQO sensitive but repair the above adducts suggests that either some other lesion(s) is responsible for increased toxicity in these mutants, or that some regions of the genome may not be repaired as effectively as bulk DNA in these mutants, or that the quality of the repair is less than in the parental cells. Clearly the inability to remove UV induced pyrimidine dimers and the (6-4) photoproduct associated with the UV5 and UV20 mutants correlates with the inability to repair 4NQO-N2 guanosine adducts. However, mutants capable of (6-4) photoproduct repair but not dimer repair (VH-1 and UV61) can repair this lesion. Hence it is possible that the same domains in these repair proteins are required for the recognition of (6-4) photoproduct repair and 4NQO-N2 guanosine adducts.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Nitroquinoline-1-oxide↗
PubMed1991

Spinal cord injury from civilian gunshot wounds: the Rancho experience 1980-88.

We performed a retrospective review of the medical records of 316 patients with spinal cord injury (SCI) secondary to gunshot wounds (GSW) admitted to Rancho Los Amigos Medical Center for rehabilitation between 1980 and 1988. There were 289 male and 27 female patients whose mean age was 25.9 years (range, 11-56 years). Of these, 238 were paraplegic (103 incomplete, 135 complete), and 78 were quadriplegic (45 incomplete, 33 complete). Forty were shot by handguns of known caliber and four by shotguns; in 272 cases, the type of weapon was unknown. A total of 230 cases sustained a single bullet wound, and 86 had multiple bullet wounds. The length of acute hospitalization, but not rehabilitation hospital stay, increased with the number of associated injuries. Rehabilitation and, hence, total length of stay was significantly less (mean, 100 and 130 days, respectively) for SCI/GSW victims than for SCI victims of motor vehicle accidents, falls, or diving accidents. The methods of calculating costs for admission were based upon Rancho Los Amigos Medical Center financial statistics. This hospital has charged for a daily occupancy fee. The fee is based upon an average of all charges for all patients. No additional fees are charged for special tests or procedures. In 1980, the average daily admission hospitalization charge was $785. In 1990, the last quoted hospital charge was $1,125. This is for the basic spinal cord injury rehabilitative stay. In general, at Rancho Los Amigos, patients are admitted for rehabilitation when all acute medical and surgical problems have been cleared and the patient is ready to participate in rehabilitation evaluation and therapy programs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗