A pictorial visual analog scale for rating severity of childhood asthma episodes

The purpose of this study was to determine whether the use of pictorial anchors improved a visual analog scale (VAS) designed to assess asthma episodes. The sample consisted of 77 children with moderate to severe asthma attending a summer camp. They rated one of two VASs, either nonpictorial (39 subjects in year 1) or pictorial (38 subjects in year 2), three times a day for 2 weeks to report the severity of their asthma symptoms. Immediately after the subjects rated the VAS, pulmonary function testing was obtained. The mean VAS scores increased 64% using the pictorial VAS while the mean PEFRs in the 2 years were almost identical, suggesting that changes on the VAS were not due to differences in pulmonary functioning. For boys, the increase in individual mean VAS score in year 2 using the pictorial VAS was 44%; for girls, the increase in individual mean VAS scores was 112%. Use of a pictorial VAS increases the range of severity of symptoms reported by children with asthma. The instrument may be a useful tool in the systematic quantifiable assessment of subjective symptomatology in pediatric asthma.

Molecular and cellular characterization of Mex-/methylation-resistant phenotype. Gene and cDNA cloning, serum dependence, and tumor suppression of transfectant strains

Methylating agents are widely distributed environmental mutagens. To identify mechanisms that protect cells against the toxic effects of methylating compounds Chinese hamster ovary (CHO) cells were transfected with human DNA and selected for resistance to methylating agents. From methylation-resistant transfectants, human DNA was cloned that conferred methylation resistance to CHO cells. A human cDNA was isolated (designated c81) encoding a protein of 410 amino acids which is partially identical to human lamp-2 encoding a lysosomal membrane glycoprotein. Transfection of c81, but not of the neo gene or a c81 antisense construct, into CHO cells gave rise to significant increases of survivors after methylating treatments. c81 mRNA is expressed both in human, CHO parental, and transfected cells, albeit in different amounts. The methylation-resistant transfectants lacked alkyltransferase activity (Mex- phenotype), did not repair O6-methylguanine in vivo, and neither showed reduced initial DNA methylation level nor increase of removal of 3-methyladenine and 7-methylguanine from DNA. They are therefore representatives of the "tolerance" phenotype. The transfectants also showed a higher serum requirement, flat growth, and a reduced tumor forming ability. The data suggest a link between altered regulation of cell proliferation and acquired resistance to methylating DNA damaging agents.

Contribution of O6-alkylguanine and N-alkylpurines to the formation of sister chromatid exchanges, chromosomal aberrations, and gene mutations: new insights gained from studies of genetically engineered mammalian cell lines

O6-methyl- and O6-ethylguanine are the major premutagenic and precarcinogenic lesions induced in DNA by monofunctional alkylating agents, albeit formed in minor amounts. The involvement of these lesions in SCE and aberration formation is less clear. We have analyzed the contribution of O6-alkylguanine to SCE and aberration formation, as well as its toxic and point mutation inducing effect in transgenic Chinese hamster ovary (CHO) cell lines that express variable amounts of human O6-methylguanine-DNA methyltransferase (MGMT). Cells that overexpress MGMT (or the bacterial Ada protein) gained resistance to the formation of alkylation-induced SCEs and aberrations, as compared to MGMT deficient cells. A correlation was apparent between the level of protection for SCEs and cell killing, indicating that both phenomena are interrelated. The protective effects were dependent on the level of MGMT expression, the agent used for alkylation, and cell cycle progression. Our data suggest that at least 2 kinds of lesions are responsible for SCE and aberration formation, namely, O6-alkylguanine and one or various N-alkylation products. The probability that O6-methylguanine is converted into cytogenetic effects has been estimated to be about 1:30 for SCEs, and 1:147,000 and 1:22,000 for chromosomal aberrations in the first and second post-treatment mitosis, respectively. The induction of SCEs and likely also of aberrations by O6-methylguanine requires two replication cycles and is supposed to involve the formation of secondary DNA lesions. Increased repair of 3-methyladenine and 7-methylguanine in CHO cells that overexpress the N-methylpurine-DNA glycosylase (MPG) after transfection with the human MPG-cDNA did not give rise to protection against methylation-induced SCEs and aberrations, probably because of incomplete excision repair. MPG overexpressing cells reacted even more sensitively to methylating agents, suggesting apurinic sites formed as a result of MPG action to be SCE and aberration-inducing lesions.

Stress factors affecting expression of O6-methylguanine-DNA methyltransferase mRNA in rat hepatoma cells

O6-Methylguanine-DNA methyltransferase (MGMT) is decisively involved in protecting mammalian cells against genotoxic effects of alkylating carcinogens. We analysed regulation of MGMT expression after exposing rat hepatoma H4IIE cells to various 'stress' factors. Treatments that damage DNA such as alkylation, hydrogen peroxide, ultraviolet or X-ray exposure, as well as restriction enzymes introduced into cells by electroporation or arrest of replication by hydroxyurea significantly induced MGMT mRNA (2.5 to 5-fold). Slight induction (up to 2.5-fold) was observed after heat shock or cadmium/zinc treatment. No or only a very weak induction (less than 1.5-fold) was observed after treatment with 6-thioguanine, 5-azacytidine, transfection of methylated DNA, depletion of MGMT by feeding with O6-methylguanine or O6-benzylguanine, serum starvation and feeding of starved cells, cAMP, TPA and dexamethasone treatment. Inhibitors of protein kinases, H8 and H9, induced MGMT mRNA. On the other hand, an inhibitor of phosphatases (sodium vanadate) prevented induction of MGMT by N-methyl-N'-nitro-N-nitrosoguanidine. The data indicate that DNA breaks are an ultimate signal for MGMT mRNA induction and that protein phosphorylation is involved in regulating MGMT expression.

Genomic differences between O6-methylguanine-DNA methyltransferase proficient (Mex+) and deficient (Mex−) cell lines: Possible role of genetic and epigenetic changes in conversion of Mex+ into Mex−

Cell lines that possess O6-methylguanine-DNA methyltransferase (MGMT) repair activity (Mex+ phenotype) or are deficient for MGMT (Mex-) are compared at genomic level. It is shown that 1) 208F rat cells do not contain the MGMT gene, as detected by Southern blot hybridization. 2) Mex- HeLa MR and CHO-9 cells express very low amounts of MGMT mRNA, as detected by PCR. The size of the MGMT specific PCR product was slightly smaller than that generated from Mex+ HeLa S3 cells. 3) HeLa MR, compared to various human Mex+ cell lines, shows a restriction fragment length polymorphism indicating mutational alteration of MGMT gene sequences. 4) Mex- cells (HeLa MR) and cells that express very low MGMT activity (GM637) exhibit hypomethylation of the MGMT gene as revealed by MspI/HpaII restriction digests. 5) Exposure of Mex- cells to 5-azacytidine and selection with N-hydroxyethyl-N-chloroethylnitrosourea (HeCNU) did not yield Mex+ revertants. With V79 cells treated with 5-azacytidine clones resistant to HeCNU were isolated. These cells were MGMT deficient and not cross-resistant to N-methyl-N'-nitro-N-nitrosoguanidine indicating the existance of a defence mechanism other than MGMT against chloroethylating agents. The data suggest down-regulation of MGMT transcription accompanied by decreasing CpG methylation, but in some cell lines also mutational alterations to be involved in extinction of the Mex+ phenotype.

Transfection and expression of human O6-methylguanine-DNA methyltransferase (MGMT) cDNA in Chinese hamster cells: the role of MGMT in protection against the genotoxic effects of alkylating agents

O6-Methylguanine-DNA methyltransferase (MGMT) is responsible for removal of O6-alkylguanine from DNA induced by alkylating mutagens/carcinogens. To analyze the involvement of O6-alkylguanine in the generation and MGMT in avoidance of various genotoxic effects of alkylating agents, we transfected Chinese hamster ovary (CHO) cells that lack MGMT activity with human MGMT cDNA cloned into a mammalian expression vector (pSV2MGMT). A high proportion (60-80%) of transfectants selected for a cotransfected neo gene survived treatment with high doses of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and N-hydroxyethyl-N-chloroethylnitrosourea (HeCNU). Parallel transfections with an expression vector containing the bacterial ada gene (pSV2ada) showed the human MGMT to be more effective than the ada expression vector in mediating alkylation resistance. Various clonal CHO cell lines have been established stably transfected with the human MGMT cDNA. The transfectants expressed human MGMT at levels ranging from 8600 to 210,000 molecules per cell. The high MGMT expressors became strongly resistant to the killing effects of MNNG, HeCNU, N-methyl-N-nitrosourea (MNU) and, to a significant lesser degree, methyl methanesulfonate (MMS) and ethyl methanesulfonate (EMS). No killing resistance was observed to N-ethyl-N-nitrosourea (ENU), though the MGMT and ada transfectants showed reduction in mutation frequency induced by this agent. Protection from mutation induction by MGMT (and ada) expression was also demonstrated for MNNG. The transfectants were also protected from the sister chromatid exchange (SCE) inducing and, to a lesser degree, clastogenic effect of MNNG and MNU, and slightly to EMS and MMS. Again no protection was observed towards ENU. Correlations between MGMT activity and resistance to a given end point suggest that, for MNNG, O6-methylguanine is the preponderant toxic, mutagenic and SCE inducing lesion. About 90% of MNNG (and MNU) induced SCEs and nearly all of the MNNG-induced gene mutations seem to be due to this adduct. For alkylation-induced chromosomal aberrations, however, and for cell killing and SCEs induced by MMS, EMS and ENU, other lesions than O6-alkylguanine appear to be of major importance. The data strongly support the view that O6-methylguanine is a genotoxic lesion and MGMT a function decisively involved in avoidance of genotoxic effects in cells exposed to MNNG and related compounds. They indicate also that it is important to take into account the property and mode of action of any given alkylating agent in assessing the protective role of MGMT against alkylation-induced genotoxicity.

Inducibility of the DNA repair gene encoding O6-methylguanine-DNA methyltransferase in mammalian cells by DNA-damaging treatments

The inducibility of the mammalian O6-methylguanine-DNA methyltransferase (MGMT) gene encoding the MGMT protein (EC 2.1.1.63) responsible for removal of the procarcinogenic and promutagenic lesion O6-alkylguanine from DNA was examined by an analysis of transcription of the MGMT gene following exposure of repair-competent (Mex+) and repair-deficient (Mex-) cells to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). While human and rodent Mex- cells (CHO-9, V79, HeLa MR) showed no detectable MGMT mRNA despite the presence of the gene in their genome, the amount of it in several Mex+ lines (NIH 3T3, HeLa S3, HepG2) paralleled their MGMT activity. However, none of these cell lines showed an increase in the MGMT mRNA level after treatment with various concentrations of MNNG. In contrast, MNNG-treated rat hepatoma cells, H4IIE and FTO-2B, both Mex+, had three- to fivefold more MGMT mRNA than the corresponding untreated controls as measured 12 to 72 h after alkylation. N-Methyl-N-nitrosourea, methyl methanesulfonate, N-hydroxyethyl-N-chloroethylnitrosourea, UV light, and X rays caused a similar accumulation of MGMT mRNA in rat hepatoma cells. Studies with inhibitors of RNA and protein synthesis indicate that the induced increase in the amount of MGMT mRNA was due to enhanced transcription of the gene. Furthermore, they revealed the turnover of the MGMT mRNA to be relatively low (half-life, greater than 7 h). Mutagen-induced increase of transcription of MGMT mRNA in H4IIE cells was accompanied by elevation of MGMT repair activity and resulted in reduction of mutation frequency after a challenge dose of MNNG. Although induction of MGMT mRNA transcription has been observed in two rodent hepatoma cell lines so far, this appears to be the first demonstration of inducibility of a mammalian gene encoding a clearly define DNA repair function. The transcription activation of the MGMT gene protects cells from the mutagenic effects of methylating agents.

Accuracy of blood glucose estimates in adolescents with diabetes mellitus

Although self-monitoring of blood glucose (SMBG) is an integral part of the daily self-care regimen for the effective management of insulin-dependent diabetes mellitus (IDDM), compliance with this task remains a significant problem, particularly for adolescents. Research should be focused on identifying other management approaches which may supplement SMBG. One potential approach involves placing greater reliance on the patient's own ability to estimate glucose levels. Although some research has examined blood glucose self-estimation in adults, little is known about this construct in children and adolescents. The purpose of the current study was to examine the accuracy of blood glucose self-estimates in adolescents with IDDM and examine the relation between child characteristics and accuracy. The results for 70 adolescents with IDDM indicated that as a group they were moderately accurate in estimating their glucose levels; however, much variability in accuracy was found among subjects. Subject characteristics were not found to be significantly related to accuracy.

[Validity of clinico-chemical and hematologic findings in the elderly--results of a randomized study]

The distinction between age-related and pathological laboratory findings in elderly is most important to diagnosis and treatment of disease. 111 pensioners (77 females, 34 men) are investigated. Pathological laboratory findings are more frequently than expected. In each case there are hints to pathological events (disease or due to treatment).

Complementation of N-hydroxyethyl-N-chloroethylnitrosourea hypersensitivity of Mex- cells by microinjection of mRNA from Mex+ cells

Chinese hamster ovary (CHO-9) and HeLa MR cells lack detectable amounts of O6-alkylguanine DNA alkyltransferase (phenotypically Mex-) and are hypersensitive to the toxic effect of N-hydroxyethyl-N-chloroethylnitrosourea (HeCNU), as compared to Mex+ derivatives. Microinjection of size-fractionated polyA+ mRNA extracted from HeLa S3 (Mex+) into CHO-9 and HeLa MR cells, or from ataxia telangiectasia (Mex+) into HeLa MR cells, gave rise to an increase in survival following treatment with toxic doses of HeCNU. Transient complementation of the Mex- phenotype was achieved with an RNA population 0.8-1 kb in size.

Casein kinase II is elevated in solid human tumours and rapidly proliferating non-neoplastic tissue

Protein kinase CKII (i.e. casein kinase II, CKII, NII) is expressed at a higher level in rapidly proliferating tissues and in solid human tumours (e.g. colorectal carcinomas) when compared to the corresponding non-neoplastic colorectal mucosa. This could be shown by (a) Western blotting of cellular extracts from solid tumours followed by immunostaining with an anti-CKII polyclonal antibody, (b) immunohistochemical staining of cells from tissue sections and (c) by activity measurements using the CKII-specific synthetic peptide (RRRDDDSDDD). The maximum observed activity in the colorectal carcinomas investigated was up to eightfold higher in the tumour specimens than in the non-neoplastic tissue (i.e. colorectal mucosa). The activity range was between 33-350 U/mg protein and in the case of colorectal mucosa 13-106 U/mg protein. The amount of CKII determined in the individual tumours was in the range 0.4-1.6 nmol/g tissue.