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PubMed1980

Preservation of red blood cells with purines and nucleosides. III. Synthesis of adenine, guanine, and hypoxanthine nucleotides.

Purine nucleotides of fresh human red cells and of red cells during storage at 4 degrees and 25 degrees C with additions of adenine, guanine, guanosine and inosine were estimated by HPLC. Six nucleotides were found in red cells: ATP, ADP, AMP, GTP, GDP, and IMP. The adenine nucleotides represented 92 per cent of the total purine nucleotides, guanine nucleotides 7 per cent and IMP less than 1 per cent. In red cells stored with adenine the total concentration of purine nucleotides increased to 125 per cent of the normal value. An adenine-free but guanine and guanine + inosine containing medium caused a decrease of the concentration of purine nucleotides by 10 to 20 per cent. When red cells were stored without adding guanine or guanosine the content of the guanine nucleotides decreased from 0.32 to 0.17 mumol/g Hb due to the decrease in the GTP content, but the GDP concentration increased slightly. In CPD-AG blood, however, the concentration of guanine nucleotides increased considerably up to 0.6 mumol/g Hb. IMP was estimated in all investigated stored red cells. In CPD-A and in CPD-AG blood 0.4 mumol/g Hb were produced during 3 weeks of storage, but twice of that in CPD-AI blood. The principles of the synthesis and the degradation of purine nucleotides in stored red cells are discussed in detail.

Adenine Nucleotides↗

PubMed1981

ABO(H) cell surface antigens in parathyroid adenoma and hyperplasia.

Forty-three cases of primary hyperparathyroidism were studied with the specific red cell adherence test (SRCA) to determine the presence or absence of ABO(H) cell surface antigens on abnormal parathyroid tissue. Of the 27 patients with the clinicopathologic diagnosis (CPD) of adenoma, 24 (89%) had lost the ABO(H) cell surface antigen of the abnormal gland. Among the 15 patients with the CPD of hyperplasia, the parathyroid tissue from three (20%) had lost its red cell antigen. In one patient, a metastasis from a parathyroid carcinoma had lost the ABO surface antigen. Several patients in whom conflicting SRCA and CPD were obtained had factors that raised doubts as to the validity of their CPD. The SRCA is a simple test that may aid in the difficult differentiation between parathyroid adenoma and hyperplasia.

ABO Blood-Group System↗

PubMed1981

Kinetic investigations on a flavoprotein oxygenase, 2-methyl-3-hydroxypyridine-5-carboxylic acid oxygenase.

In the presence of NADH and O2, 2-methyl-3-hydroxypyridine-5-carboxylate oxygenase (EC 1.14.12.4) from Pseudomonas sp. MA-1 catalyzes reductive oxygenation of 2-methyl-3-hydroxypyridine-5-carboxylate (Cpd I) to yield alpha-N-(acetylaminomethylene)succinic acid (Cpd A). Steady state kinetic data and studies with alternate substrates are consistent only with an ordered mechanism in which Cpd I binds first, followed by NADH; the first product, NAD+, is then released. This event is followed by oxygen binding, and finally release of the oxygenated and reduced cleavage product, Cpd A. This kinetic mechanism was confirmed by studying inhibition by NAD+, which binds competitively with oxygen, but not with NADH. The kinetic mechanism of this reaction resembles that proposed for bacterial flavin monooxygenases that catalyze hydroxylation of aromatic homocyclic compounds.

Flavoproteins↗

PubMed1981

Corticosterone binding in myocardial tissue of rats after chronic stress and adrenalectomy.

Male rats were trained to swim for 9-10 days to assess the effect of chronic stress on the capacity and affinity of specific glucocorticoid binding in the cytosol fraction of myocardial tissue. A significant decrease in the binding capacity for corticosterone (Cpd B) was found 24 hours after the last swimming test, while the affinity constant remained unchanged. Contrary to Cpd B binding, there was no change in the capacity of dexamethasone binding, and there was no decrease in the Cpd B binding capacity in rats which had been adrenalectomized 2 days prior to the training period. We conclude that daily swimming for 9-10 days alters the numbers of cytoplasmic Cpd B binding sites in the face of increased adrenocortical activity, while not affecting dexamethasone binding in the cytosol fraction of myocardial tissue.

Adrenalectomy↗

PubMed1981

[Changes in the pump function of the right ventricle during "pressure-autotransfusion" with citrate and heparin (author's transl)].

Nine anaesthetized, splenectomized dogs, heparinized with 300 IU/kg bodyweight heparin i.v. had one tenth of their total blood volume returned to them by autotransfusion under maximum pressure with the Bentley-system. For the "Heparin"-autotransfusion (n = 49) 1:5 0,9% NaCl was added to the blood; whilst for the "Citrate"-autotransfusion 1:5 ACD-B(n = 28) or CPD (n = 30) stabilisor was added. Autotransfusion was performed as follows: Heparin-ACD-B- Heparin-DPD- Heparin-ACD-B etc. The pump function of the right ventricular myocardium was measured by the force of contraction (PRV, IP, SV, T1) as well as by criteria of contractility (dp/dtmax, VCEmax, KI1, KI2). Immediately after acute bleeding a reduction of the force of contraction to 50% was seen, but the contractility remained unchanged. During the maximum pressure autotransfusion of the blood the force of contraction consistently increased irrespective of the anticoagulant used. The contractility remained unchanged. In the following phase the force of contraction and the contractility normalised when heparin was employed, whilst when citrate was used there was a reduction of the force of contraction and of the contractility corresponding with the different dose of citrate of ACD-B and CPD. This short phase was followed by spontaneous stabilisation of the circulation. The force of contraction and the contractility returned to normal when heparin and ACD-B were employed, whilst a reduction of these criteria occurred when CPD was used. From these findings, the scheme of anticoagulation for citrate under clinical conditions should be modified by a prior injection of 2,000-3,000 IE of heparin i.v. and the addition of citrate in the ratio of 1:7 for ACD-B or 1:8 for CPD.

Animals↗

PubMed1994

Effect of dietary protein restriction on the progression of renal failure: a prospective randomized trial.

One hundred twenty-eight patients with different renal diseases and chronic renal failure, stratified according to the underlying disease, were enrolled in a randomized controlled trial to investigate the effects on the rate of decline of renal function of two diets, a controlled protein diet (CPD) of 1 g protein/kg ideal body-weight (i.b.w.)/day, and a low-protein diet (LPD) of 0.6 g protein/kg i.b.w./day, given for 27.1 +/- 21.8 months. Dietary compliance was assessed by a dietary questionnaire, dietary interviews and measurement of 24-h urinary urea excretion. At the end of 6 months, actual mean protein intake was higher than expected (1.06 +/- 0.25 g/kg i.b.w./day) in CPD patients, and (0.80 +/- 0.21 g/kg i.b.w./day) in LPD patients: values were similar at 12 and 18 months after the time of enrollment. The end-point, defined as halving of creatinine clearance, was reached in 40% of patients on CPD, and in 28.6% of those on LPD (P = 0.038 by comparative life-table analysis). Multivariate regression analysis confirmed that CPD was associated with a higher risk of progression than LPD, and that two additional parameters (creatinine clearance at the time of randomization and average proteinuria during the follow-up) were significant independent risk factors, even more important than protein intake.

Diet, Protein-Restricted↗

PubMed1995

Immunizations in children on PD: current guidelines and recommendations.

Antibody responses to currently recommended immunizations in pediatric patients on chronic peritoneal dialysis (CPD) have been measured and the results have been variable. Although the incidence of vaccine-preventable disease in pediatric CPD patients is not known, it appears that protection from these diseases may be reduced. The explanation for the abnormal response to vaccines might include lower seroconversion rates in these patients, with lower antibody titers or levels. Also a rapid decline of antibody levels or titers may occur as a consequence of continuous peritoneal dialysis. Specific vaccines that may result in a less than optimal response in pediatric CPD patients include hepatitis B virus, hemophilus influenza type b, measles, mumps, rubella and pneumococcal vaccine. Patients who receive these immunizations should be monitored closely. Increased vaccine dosage, reinforced vaccination schedules, as well as concomitantly administered adjuvant immuno-modulators may play an important role in more effective vaccination of pediatric CPD patients. It is important that vaccine response be monitored in these patients by measuring specific antibody titers or levels to ensure adequate protection from vaccine-preventable illness.

Adolescent↗

PubMed1996

Hepatitis C antibodies in patients on peritoneal dialysis: prevalence and risk factors.

Our objective was to determine the prevalence of the antibody to hepatitis C (anti-HCV) in a population of end-stage renal failure patients on continuous peritoneal dialysis (CPD) and study the possible risk factors associated with anti-HCV seropositivity and seroconversion. A cross-sectional study included 155 adult patients enrolled in the CPD program in a single renal unit of a teaching hospital who were screened for anti-HCV by second-generation enzyme immunoassay, which was confirmed by recombinant immunoblot assay. Serum was also assayed for hepatitis B surface antigen (HBsAg). History of renal transplantation, blood transfusions, and exposure to hemodialysis was obtained from medical records. Ten of 155 patients (6.5%) in this study population were anti-HCV positive [anti-HCV(+)] and 11/155 (7.1%) were HBsAg positive; no patient was positive for both. All the anti-HCV(+) patients were on continuous ambulatory peritoneal dialysis (CAPD); no continuous cycling peritoneal dialysis (CCPD) patient was anti-HCV(+). Exposure to hemodialysis was a risk factor for anti-HCV seropositivity, with 7 out of 10 (70%) anti-HCV(+) patients having been on hemodialysis compared to 55/134 (41%) anti-HCV(-) (p < 0.05, Fisher's exact test). No difference was noted between anti-HCV(+) and anti-HCV(-) groups in relation to age, gender, duration on CPD, renal transplantation, or exposure to blood transfusions. Seroconversion occurred in only one patient after a mean observation period of 20 +/- 0.6 months. The prevalence of anti-HCV seropositivity in this population of CPD patients is 6.5%, and HBsAG 7.1%. Exposure to hemodialysis is a significant risk factor for development of anti-HCV seropositivity. Seroconversion rate appears to be low.

Adolescent↗

PubMed1996

Nicotine patch therapy in adolescent smokers.

OBJECTIVE: To evaluate the safety, tolerance, and efficacy of 24-hour nicotine patch therapy in adolescent smokers who were trying to stop smoking. DESIGN: Nonrandomized, open-label, 6-month clinical trial. SETTING: Five public high schools in the Rochester, MN, area. SUBJECTS: Twenty-two adolescent smokers, aged 13 through 17 years, with current smoking rate of 20 or more cigarettes per day (cpd). INTERVENTION: Daily nicotine patch therapy for 8 weeks (22 mg/d for 6 weeks followed by 11 mg/d for 2 weeks). Weekly individual behavioral counseling and group support continued for 8 weeks with follow up visits at 3 and 6 months and a mailed survey at 1 year. MAIN OUTCOME MEASURES: Self-reported smoking abstinence verified by expired air carbon monoxide of 8 ppm or less, nicotine withdrawal symptoms, adverse experiences, and blood cotinine levels. RESULTS: Subjects had a mean +/- SD smoking rate of 23.3 +/- 5.0 (range, 20 to 35) cpd at study entry and 2.6 +/- 1.6 years of smoking; the mean age was 15.9 +/- 1.2 (range 13 through 17) years, and 68% were girls. Of the 22 participants, 19 (86%) completed patch therapy, 3 (14%) had biochemically validated smoking cessation at week 8, and 1 continued to be smoke free at 3 and 6 months after patch initiation. There was a significant decrease from baseline in the mean nicotine withdrawal scores for days 4 and 7 of week 1 and the mean for weeks 2 through 8. Skin reactions were the most common adverse event. As the worst skin reactions, 55% had erythema only, 5% had erythema and edema, and 9% had erythema and vesicles, whereas 32% had no skin reactions. Other reported adverse events were headaches (41%), nausea and vomiting (41%), tiredness (41%), dizziness (27%), and arm pain (23%). None of these were considered serious, life threatening, or led to the discontinuation of patch therapy. In adults with comparable smoking rates, we found that the adolescents had lower blood cotinine levels. Those smoking 20 to 25 cpd had cotinine levels of 146 +/- 84 (adolescents) vs 260 +/- 98 (adults) ng/ml, and those smoking 26 to 35 cpd had levels of 169 +/- 73 vs 276 +/- 110 ng/ml, respectively. CONCLUSION: Nicotine patch therapy seems safe in adolescent smokers. Placebo-controlled trials are needed to establish the efficacy of nicotine patch therapy in adolescents.

Administration, Cutaneous↗

PubMedDate not supplied

Fractional urea clearance estimates using two anthropometric formulas in continuous peritoneal dialysis: sex, height, and body composition differences.

OBJECTIVE: To compare estimates of urea volume (V) and KT/V obtained by the Watson and Hume anthropometric formulas, and to identify the similarities and differences between these estimates. DESIGN: Theoretical analysis applying wide variations in the determinants of anthropometric V (age, height, weight) in hypothetical women and men. Analysis of urea kinetic studies performed in patients on continuous peritoneal dialysis (CPD). SETTING: Four dialysis units in Albuquerque, two in Athens, and two in Thessaloniki. PARTICIPANTS: Three hundred and two CPD patients who had 440 urea kinetic studies. INTERVENTION: Standard urea clearance was performed by 24-hour collections of urine and drained dialysate followed by blood sampling. V was estimated by both the Watson and Hume formulas. MAIN OUTCOME MEASURES: Estimates of V and KT/V were compared separately in women and men by Student's t-test, linear regression, and limits of agreement (mean difference +/- 2 SD). The agreement of the KT/V estimates was also tested by the kappa ratio using a value of 1.70 weekly as the lowest acceptable K/TV. RESULTS: The theoretical analysis indicated important disagreement only in extreme variations from the ordinary in height and, to a lesser extent, weight. Differences due to height variation were pronounced only in hypothetical women. CPD patient findings were as follows: in women, Watson V and weekly KT/V were 30.4 +/- 4.4 L and 2.10 +/- 0.61, respectively. Corresponding Hume estimates were 30.3 +/- 5.4 Land 2.1 2 +/- 0.66, respectively. Corresponding estimates for men were 40.5 +/- 5.7 L and 1 .92 +/- 0.57 (Watson) plus 41.4 +/- 5.6 L and 1.88 +/- 0.57 (Hume), respectively. By linear regression, KT/V(Hume) = -0.083 + 1.052 (KT/V(Watson)), r = 0.961 (women); and KT/V(Hume) = -0.026 +/- 0.992 (KT/V(Watson)), r = 0.985 (men). Limits of agreement were -1.41 L and 2.10 L for V, and -0.15 and 0.14 weekly for KT/V. In 94.3% of the cases, KT/V(Watson) and KT/V(Hume) agreed (both > 1 .70 or both < 1 .70 weekly). Kappa ratio was 0.875 (excellent agreement). The concordant and discordant groups differed in height and degree of obesity, in agreement with the theoretical analysis. CONCLUSION: The Watson and Hume formulas provide similar estimates of V and KT/V in CPD patients. Differences may be noted only if women's height or, to a lesser extent, both sexes' weight is at a great variance with the ordinary values.

Adult↗

PubMed1998

Contribution of tubular anion and cation secretion to residual renal function in chronic dialysis patients.

The clearance of organic ions by the tubules may contribute to the removal of uremic waste products in dialysis patients. The renal excretion of an exogenous anion p-aminohippurate (PAH) was investigated in 10 peritoneal dialysis patients and 10 hemodialysis patients during one clearance period and compared with the clearance of creatinine (Ccr) and inulin (CIn). The clearance period was 24 hours in the peritoneal dialysis patients and one interdialytic interval of 3 days divided in 4 parts [CPA-D] in hemodialysis patients. In peritoneal dialysis patients the renal clearance of total PAH (median 14.3 ml/min, range 3.8-33.0) exceeded the CIN (median 3.2 ml/min, range 1.6-11.2, p < 0.005) and Ccr (median 4.0 ml/min, range 1.7-15.0, p < 0.005). A positive correlation was found between the tubular clearances of creatinine (cationic pathway) and of total PAH (anionic pathway, r: 0.72, p <0.02). In hemodialysis patients the clearance of total PAH (CPA: median 2.0, range 0.8-9.6; CPD: median 3.8, range 1.7-15.4) also exceeded the clearance of inulin (CPA: median 1.5, range 0.2-3.4; CPD: median 2.7, range 0.9-4.4) in the beginning and the end of the interdialytic interval (p < 0.005). The CIN and the clearance of total PAH increased during the interdialytic interval, but the Ccr (CPA: median 2.2, range 0.4-8.9, CPD: median 2.9, range 1.2-4.6) remained stable. Thus, the change in tubular clearance of creatinine and PAH was opposite during the interdialytic interval: it increased for total PAH and decreased for creatinine. The CTPAH/CIN ratio in hemodialysis patients was lower than in peritoneal dialysis patients. In CPA it was median 1.6 (range 1.1-5.6, p < 0.05) and in CPD it was median 1.7 (range 1.1-5.0, p < 0.02) and in the peritoneal dialysis patients it was median 3.6 (range 1.5-9.1). We conclude that tubular clearances contribute to the residual renal function in dialysis patients, but the tubular handling of anions and cations in relation to the residual GFR is different between peritoneal and hemodialysis patients. A difference in clearance of organic acids caused by the dialysis techniques may be an explanation for the differences in clinical outcome between the two dialysis modalities.

Adult↗

PubMedDate not supplied

[Factors predicting survival in patients on peritoneal dialysis].

OBJECTIVE: To determine the factors associated with survival in a cohort of 74 patients with end-stage renal disease (ESRD) undergoing chronic peritoneal dialysis (CPD). SETTING: The study was carried out at a general hospital of the Instituto Mexicano del Seguro Social. DESIGN: Analysis of a retrolective cohort under a nested case control design. PATIENTS AND METHODS: The variables studied included age, gender, cause of ESRD (diabetic or non-diabetic), socioeconomic status, modality of CPD (intermittent vs continuous ambulatory peritoneal dialysis), catheters per patient, rate of peritonitis, levels of serum creatinine and albumin at the beginning of the CPD. RESULTS: During a 75.1 years-patient follow up, there were 41 deaths (cases). The main cause of death was peritonitis. The cumulated survival of the 74 patients was 64%, 29% and 13% at 12, 24 and 33 months, respectively. Intermittent peritoneal dialysis, the rate of peritonitis and the level of basal serum albumin were associated with a decreased survival in a univariate analysis. Only a high rate of peritonitis was associated with an increase in mortality rate independent from other variables (p = 0.002). CONCLUSIONS: The probability of survival in ESRD in our hospital was low in relation to other nephrology departments of Mexico and other countries. A high rate of peritonitis proved to be an important independent predictor of a lesser survival rate in patients under CPD in our institution.

Adult↗

PubMed2001

A single (6-4) photoproduct inhibits plasmid DNA replication in xeroderma pigmentosum variant cell extracts.

The human skin cancer-prone disease xeroderma pigmentosum variant (XPV) results from a mutation in the human RAD30 gene, which encodes the lesion bypass DNA polymerase eta. XPV cells are characterized by delayed completion of DNA replication and increased mutagenesis following UV-irradiation. Using extracts of an XPV lymphoblast cell line (GM2449C) that has a truncating mutation in the RAD30 gene, we investigated the effect of a (6-4) photoproduct and a cyclobutane pyrimidine dimer (CPD), at a unique -TT- site on either the leading or lagging strand, on plasmid DNA replication. Compared to normal cell extracts, XPV cell extracts have a reduced capacity to carry out complete replication of DNA containing either a (6-4) photoproduct or a CPD on the leading strand, whereas there is little difference between the two cell extracts in replication of DNA containing a lesion on the lagging strand. Inhibition of replication in the presence of a (6-4) photoproduct is attributed to arrest of nascent DNA strand synthesis at the lesion site; in XPV cell extracts, the proportion of arrested products is increased compared to that of normal cell extracts. These results are consistent with a requirement for functional DNA polymerase eta in the replication of a double-stranded plasmid containing either a (6-4) photoproduct or a CPD, on the leading but not the lagging strand.

Base Sequence↗

PubMed1995

Field emission SEM comparison of four postfixation drying techniques for human dentin.

Critical-point drying (CPD) is generally considered essential for the preparation of biologic specimens for electron microscopy. Several attempts have been made to introduce alternative techniques. More recently, this problem has arisen in dentistry, because of the new developments in dentin bonding. The present study focuses on three alternative techniques to CPD: hexamethyldisilazane (HMDS) drying, Peldri II drying, and air drying. Twenty-four dentin disks were obtained from noncarious extracted human molars by microtome sectioning parallel to the occlusal surface. The dentin surfaces were etched with polymer-thickened, silica-free, 10% phosphoric acid semigel, fixed, dehydrated, and dried with one of the four techniques. The specimens were observed in two perpendicular planes, showing dentinal tubules in longitudinal view and cross-section, using a field emission scanning electron microscope. The intertubular demineralized dentin zone was composed of three different successive layers, which did not substantially differ between CPD and Peldri II drying, but were more evident in HMDS-dried specimens: first, an upper layer of denatured collagen and residual smear layer particles, with sectioned collagen fibrils and few open intertubular pores; second, an intermediate layer of closely packed cross-sectioned collagen fibers; and third, a deeper layer with unfilled spaces, scattered hydroxyapatite crystals, and few collagen fibers. HMDS drying seemed to preserve better the collagen network and the microporosity of the demineralized dentin surface. Moreover, HMDS drying is easy to perform. The air-drying method caused some artefacts, such as surface collapsing and thickening of the denatured collagen layer.

Air↗

PubMed1990

Use of Peldri II as a sublimation dehydrant in place of critical-point drying in fracture-label cytochemistry and in backscattered electron imaging fracture-label.

Peldri II, a fluorocarbon compound solid at room temperature, was used as a sublimation dehydrant in place of critical-point drying (CPD) in freeze-fracture cytochemistry. Its applicability to the fracture-label replica method was demonstrated using freeze-fractured rat pancreas labeled with Helix pomatia lectin-gold complex and phospholipase A2-gold complex for the detection of glycoconjugates and phospholipids, respectively. No difference in morphology and labeling pattern was detected in CPD-treated and Peldri II-treated tissue samples. The use of Peldri II was further extended to freeze-fractured rat duodenum labeled with wheat germ agglutinin-ovomucoid-gold complex. Again comparable results were obtained when duodenal samples were prepared according either to the conventional CPD method or to the Peldri II sublimation method. Freeze-fractured replicas of hamster ovaries labeled with Ricinus communis I-gold complex revealed that Peldri II could also be used as a sublimation dehydrant for preparing tissue samples for examination in the scanning electron microscope by the backscattered electron imaging mode.

Animals↗

PubMed1995

Profile of immunoglobulin heavy chain variable gene repertoires and highly selective detection of malignant clonotypes in acute lymphoblastic leukemia.

The predominant B cell immunoglobulin heavy chain variable gene (IgH-V) usage and the uniquely rearranged, clonotype-specific variable-diversity-joining region gene (VDJ) sequences were identified in patients with B cell acute lymphoblastic leukemia (B-ALL) using a novel DNA-based gene amplification strategy. The approach allows a thorough and sensitive determination of the number of clonal leukemic IgH rearrangements and their precise V gene usage. This strategy may be applied in the detection of minimal residual disease, in surveillance after induction of disease-free states, and in analyzing the effectiveness of purging autologous bone marrow of malignant clones. An initial primary polymerase chain reaction (PCR), directed by an IgH-J generic primer and a complement of family-specific IgH-V primers, defined the major B cell IgH-V gene usage. Use of an IgH-J generic primer supplanted the use of a constant region primer anchor and thus eliminated the need to target mRNA by the traditional RNA reverse transcription-PCR amplification method. Monoclonality of rearranged VDJ bands was further substantiated by high-resolution denaturant gel electrophoretic analysis. The predominant amplified bands were subcloned and sequenced. By sequencing through VDJ juxtaposed regions, that is, the third complementarity-determining region, clonotype-specific primers were developed and used in a secondary clonotype primer-directed PCR (CPD-PCR) to detect, with extreme sensitivity and specificity, a unique B cell clone. Analysis of the products of the CPD-PCR permitted the detection of a single malignant cell among 1 million polyclonal cells and superseded the constraints of prior studies that have provided a limited evaluation of family variable gene repertoire usage. Leukemic clonal rearrangements were detected in 100% of the eight cases of pediatric and two cases of adult B-ALL studied. Two or more clonal IgH-VDJ amplified sequences were observed in 50% of the B-ALL bone marrows analyzed. In two cases, clonotype-specific oligodeoxynucleotide primers, derived from B-ALL VDJ sequences, directed the secondary CPD-PCR, and disease activity was monitored after chemotherapy and allogeneic bone marrow transplantation.

Adult↗

PubMed1994

Preferential repair of ultraviolet light-induced DNA damage in the transcribed strand of the human p53 gene.

Mutations in the p53 tumor suppressor gene have been found in most human tumors. Analyses of the spectrum of p53 mutations in certain tumor types have shown a bias for mutations originating from lesions presumed to be in the untranscribed strand of the gene. This implies strand specificity for the formation or repair of DNA damage. We measured the induction and repair of ultraviolet light-induced cyclobutane pyrimidine dimers (CPD) in each strand of the human p53 gene in a normal human lung fibroblast cell line using quantitative Southern hybridization. We found that the removal of CPD from the transcribed strand was more rapid than that from the untranscribed strand of this gene, although the frequency of CPD induction was similar in both strands. Preferential repair of the transcribed strand of the p53 gene may account for the mutational spectra of this gene in human tumors.

Cells, Cultured↗

PubMed2001

Tumor cell growth inhibition and extracellular signal-regulated kinase (ERK) phosphorylation by novel K vitamins.

2-(2-hydroxy-ethylsulfanyl)-3-methyl-1,4-naphthoquinone or CPD-5, a K vitamin analog, was previously indicated to be a potent growth inhibitor for Hep 3B hepatoma cells in vitro. Here, we show that CPD-5 and two newly synthesized analogs, 2-(2-hydroxy-ethylsulfanyl)-3-methyl-5- nitro-1,4-naphthoquinone (PD-37) and 2-(2-hydroxy-ethylsulfanyl)-3- methyl-5-acetylamino-1,4-naphthoquinone (PD-42), are potent growth inhibitors of 13 different human cancer cell lines, with IC50 values in the range of 3-54 microM. Phospho-ERK was induced by each of three K vitamin analogs in every cell line in a dose-dependent manner, at growth inhibitory doses. ERK phosphorylation and growth inhibitory effects were strongly correlated, with p=0.0080 for CPD-5, p=0.0076 for PD-37 and p=0.0251 for PD-42. The induction of phospho-ERK and growth inhibition were antagonized by thiol-containing anti-oxidants, but not by catalase, consistent with a possible arylating mechanism. The data show a novel class of growth inhibitors with a wide spectrum of action that induces ERK hyper-phosphorylation, as a possible new growth inhibitory feature.

Antioxidants↗