Biomedical subjects
Publications and source records attributed to E Schwarz.
CenA from Cellulomonas fimi is a beta-1,4-endoglucanase that binds tightly to cellulose. X-ray-scattering analyses show that the enzyme is tadpole-shaped: the previously identified catalytic and cellulose-binding domains comprise the head and tail respectively. It appears that this structural and functional organization is common to several cellulases from bacteria and fungi.
The citrate transport determinant of plasmid pES1 from Klebsiella pneumoniae [Schwarz E. and D. Oesterhelt (1985) EM BO J. 4, 1599-1603] has been subcloned in Escherichia coli DH1. The DNA sequence of a 1723-base fragment that codes for the citrate carrier has been determined and the gene product has been characterized with the T7 promoter system. The DNA fragment contains an open reading frame of 1332 base pairs and codes for a protein of 444 amino acids. The hydropathy profile suggests that the protein is very hydrophobic and contains 12 membrane-spanning segments centered around a hydrophilic core. The gene for the citrate carrier has 66% similarity with a citrate carrier determinant from a naturally occurring plasmid responsible for secondary transport of citrate across the cytoplasmic membrane of E. coli.
The purpose of the present report is to establish to what extent dental anxiety is expressed by young adults with a long history of regular dental care, to analyze whether expressions of dental anxiety vary during young adulthood in response to different dental care delivery programs, and to study which factors might account for existing expressions of dental anxiety. The study comprised 697 persons who participated in a longitudinal study on alternative dental care programs, running from the youngsters' 16th to their 19th yr. At the end, Corah Dental Anxiety Scale (DAS) was applied through self-completed questionnaires. Overall DAS-mean was 7.26; women expressed more anxiety than men (7.73; 6.78). Significant association between anxiety expressed at the end and at the start of the study indicated that dental anxiety was probably present at an early age. No association was found with utilization of dental services. A multiple regression analysis indicated early expressed dental anxiety and negative self assessment of dental health as important predictors for dental anxiety, while sex, negative assessment of gingival health, and dental program were of less importance, altogether explaining 22% of the DAS score variation. The risk group concept currently employed by the Public Child Dental Health Services might be extended to include expressions of dental anxiety.
The E6 and E7 genes of the cancer-associated human papillomavirus (HPV) types 16 (HPV16) and 18 (HPV18) can induce cell immortalization in vitro in normal human keratinocytes. This, however, is not associated with tumorigenicity in vivo. On the other hand, tumorigenicity of HPV18-positive HeLa cervical carcinoma cells can be suppressed by fusion of HeLa cells with normal human keratinocytes or fibroblasts. We have addressed the question of whether suppression of tumorigenicity in HeLa x fibroblast hybrid cells might be due to a reduced ability of these cells to express the HPV18 E6-E7 genes in vivo. Nontumorigenic hybrid cells and tumorigenic hybrid segregants were transplanted as organotypical cultures or injected subcutaneously into immunocompromised mice and were analyzed for HPV18 E6-E7 gene expression by RNA-RNA in situ hybridization. The tumorigenic hybrid cells showed a continuous and invasive growth that was associated with high levels of HPV18 E6-E7 mRNAs at all time points examined. In contrast, the nontumorigenic hybrid cells stopped cell proliferation approximately 3 days after transplantation. At this time they expressed the E6-E7 genes at low levels, whereas at day 2 high expression levels were observed. However, the mRNA levels of the cytoskeletal genes beta-actin and vimentin remained high for at least 14 days, demonstrating that inhibition of growth and of HPV18 E6-E7 gene expression was not due to cell death. These results suggest that growth inhibition of the nontumorigenic HeLa x fibroblast hybrid cells in vivo might be caused by suppression of HPV18 E6-E7 gene expression and are compatible with the idea of an intracellular surveillance mechanism for HPV gene expression existing in nontumorigenic cells.
The use of antibodies permits the study of oncogene product expression in cells and tissues. However, quantitation of the levels of expression in immunohistochemical preparations is beset by difficulties, and the available scoring system provide semiquantitative data at best. Here we describe the use of computer-assisted image analysis for determination of oncoprotein levels in a model system and compare the results with those generated by flow cytometric analysis. The oncogene products measured are located in the nucleus (c-myc p62 and c-fos p55), the inner surface of the membrane (c-ras p21), and both sides of the membrane (c-erbB-2 p185). In each instance, both analytic modalities yielded concordant results. Our data indicate that computer-assisted image analysis is a useful tool for quantitating cell components in immunohistochemical preparations.
The sequences upstream and downstream of the cloned gene for the alpha-subunit of the Na+ pump oxaloacetate decarboxylase of Klebsiella pneumonia were determined. An open reading frame in the upstream region was identified as the gene for the gamma-subunit, and an open reading frame in the downstream region represents the gene for the beta-subunit. The deduced primary structure of the gamma- and beta-subunit was confirmed by protein sequencing of about 37 and 22%, respectively, of each polypeptide chain. The gene for the gamma-subunit has a GC content of 64% and codes for 83 amino acids. The protein is not processed at its amino terminus or at its carboxyl terminus. The gene for the beta-subunit has a GC content of 66% and codes for 327 amino acids. The protein contains a blocked aminoterminal methionine residue. Whether processing occurs at the carboxyl terminus is unknown. Hydropathy calculations defined one transmembrane helix in the amino-terminal part of the gamma-subunit and a hydrophilic carboxyl-terminal part that is certainly not embedded within the lipid bilayer. A proline- and alanine-rich sequence in the carboxyl-terminal part may provide the protein with conformational flexibility. According to hydropathy and acrophilicity calculations, the secondary structure of the beta-subunit may be formed with 5 or 6 intramembrane helical segments.
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Mutants of adenovirus type 12 adapted to growth in Vero cells were studied by restriction enzyme and sequence analysis. Plaque-purified mutants were isolated either after long-term passage of the virus in Vero cells (CS-1, CL-1) or from Vero cells transfected with viral DNA (11-g, 12-k). The plaque-forming activity of these mutants was equal or even slightly higher in Vero cells than in HeLa cells, whereas the activity of wild-type virus in HeLa cells exceeded that in Vero cells by about one to two orders of magnitude. All mutants tested had an insertion of variable length consisting of adenoviral sequences at the right end of the viral genome. Sizes of the insertions were determined to be 294 bp (CS-1, 12-k), 560 (11-g), or 180 bp (CL-1). Additional insertions of multiple size and less than equimolar amount were detected and seem to exist in some of the viral particles. Furthermore, all four mutants tested showed an identical 69-bp deletion in the first exon of the E1a gene.
From 16 to 19 years of age three groups of young adults received alternative dental programs on termination of the Public Child Dental Health Service (PCDHS) in different municipalities: public group, n = 386; mixed group, n = 161; and private group, n = 261. Dental caries status at the start of the study was assessed from the standard PCDHS records, and caries, plaque, and gingivitis were examined in an epidemiologic survey at the end. Caries experience at 16 years was 11.6 DMFS, highest in the mixed group and increased in all groups during the study. Initial placement in caries severity zones did not change. Visible plaque index (VPI) and gingival bleeding index (GBI) showed that plaque and gingival bleeding were present in most subjects, but rather few surfaces were affected. Association between gingival bleeding and non-use of dental services was found. Overall, it is concluded that none of the alternative programs differed from each other in having measurable effects on the oral health status.
From age 16 to 19 years three groups of young adults received alternative dental programs on termination of the Public Child Dental Health Service (PCDHS) in different municipalities: public group, n = 386; mixed group, n = 161; and private group, n = 261. During the entire study information on dental service use by the participants was taken from the records and National Health Insurance files. All dental services were calculated relative to a standardized Dental Service Unit defined by the value of a dental examination. During the entire study a mean of 30.53 Dental Service Units were provided, corresponding to 10.18 per year. More than half were of a diagnostic preventive character, and well over one-fourth were fillings. Irrespective of dental program, differences in dental services were noted with regard to utilization of dental services and to initial caries status. Users with high caries experience also received more fillings, but fewer preventive services. No association was found between gingival status and dental services provided.
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The gene encoding the alpha-subunit of the Na+ pump oxalacetate decarboxylase of Klebsiella pneumoniae was cloned and sequenced. The deduced primary structure of the protein was confirmed by protein sequencing of about 30% of the polypeptide chain. The gene has a GC content of 67% and codes for 596 amino acids. The N-terminal methionine is removed in the mature protein which has a calculated molecular mass of 63,600 daltons. The protein consists of two different domains that are connected by a stretch of amino acid residues susceptible to proteolytic cleavage. Limited proteolysis of the native enzyme with trypsin produced fragments of about 51 kDa and 10.2 kDa, the latter of which started with valine 491 and contained the biotin prosthetic group. Peptide sequencing indicated binding of the biotin prosthetic group to lysine 561, 35 residues from the C terminus. The decarboxylase contains an extended alanine- and proline-rich region (positions 502-532) on the N-terminal side of the 10.2-kDa biotin domain. This sequence includes a total of 16 alanine and 9 proline residues.
In cervical carcinomas and cell lines derived from these tumors the DNA of specific types of human papilloma viruses (HPVs) is integrated into the host cell genome. The two viral open reading frames E6 and E7 are consistently transcribed in tumors and cell lines, and the respective proteins were detected in cells cultured in vitro. As shown here, modulation of HPV 18 E6 and E7 gene expression in C4-1 cervical carcinoma cells is accompanied by an altered cell growth. HPV 18 E6 and E7 expression can be enhanced by glucocorticoid treatment of C4-1 cells, and an increased cell proliferation is observed. In contrast, after introduction of complementary RNA to the HPV 18 E6 and E7 open reading frames, their expression is inhibited, and decreased cell growth is observed. These results support the hypothesis that expression of HPV E6 and E7 open reading frames is directly involved in growth regulation of cervical carcinoma cells.
We recently reported the transcription patterns of human papillomavirus (HPV) type 18 sequences in human cervical carcinoma cell lines. The open reading frames (ORFs) E6* and E6 represent the 5'-terminal cistrons in HPV18 mRNAs. ORF E6* was assumed to be specific for HPV types associated with genital carcinomas. To identify the predicted gene product, ORF E6* from a HeLa cDNA clone was expressed as an MS2 fusion protein in Escherichia coli. The C-terminal 23 amino acid residues were chemically synthesized. A panel of monoclonal antibodies was generated, recognizing E6* and E6* plus E6, respectively. In human cervical carcinoma cell lines grown in vitro these monoclonal antibodies specifically immunoprecipitate the putative Mr 17,000 and 18,000 HPV18 E6 proteins in nuclear protein fractions. In a HPV18 DNA containing human cervical carcinoma established in nude mice, these monoclonal antibodies specifically immunoprecipitate a polypeptide with a molecular weight of 6500 as predicted for the HPV18 ORF E6* gene product in a nuclear protein fraction.
We have examined the effects of mutations in the six allele-specific modifier genes su(Hw), e(we), su(f), su(s), su(wa), and su(pr) on the expression of 18 modifiable alleles, situated at 11 loci. Ten of the modifiable alleles are associated with insertions of the gypsy retrotransposon and the others include alleles associated with insertions of copia and 412. We tested or retested 90 of the 108 possible combinations and examined the expression of modifiable alleles in flies mutant for pairs of modifier genes in various heterozygous and homozygous configurations. Our principal findings are: (1) a screen of 40,000 mutagenized X chromosomes yielded three new mutations in known modifier genes, but revealed no new modifier genes; (2) the modification effects of different mutations in a given modifier gene were qualitatively similar; (3) each of the six modifiers suppressed some modifiable alleles, enhanced others, and had no noticeable effect on still others; (4) the modifier genes could be placed in four classes, according to their effects on the gypsy-insertion alleles; and (5) the effects of mutations in different modifier genes combined additively. Implications of these results for models of modifier gene action are discussed.
A system for handling complaints of dental malpractice was established in 1983 in an agreement between the Danish Dental Association and the National Health Insurance. Description is given of the system comprising county dental complaints boards and a national dental complaints board. Reports of all complaints directed to the boards during the first 3 1/2 years were analyzed: 533 complaints to the county boards and 111 appeals to the national board. The complaints corresponded to 5 complaints per 100 dentists per year with considerable regional variation. Most complaints were reported in fixed and removable prosthetics, and most claims were of an economic nature. Almost two-thirds of the complaints were supported by the boards. Themes for further study as well as certain problems concerning consumer satisfaction weighed against the responsibility to survey dentists' work are pointed out.
Three groups of young adults were offered three different dental programs from ages 16 to 19: one group of 386 persons continued preventive and curative dental care in the Public Child Dental Health Service (Public group), one group of 161 persons was offered dental care with private dental practitioners of own choice with care paid by the municipality and the health insurance (Mixed group), and one group of 261 persons entered the general young adult dental program under the National Health Insurance with free choice of private dental practitioner with reimbursement of about 75% from the insurance (Private group). Almost 100% of the Public group used the dental services continuously. Less than half of the Mixed group and about two thirds of the Private group went regularly to a dentist, women more than men. Discrepancies were found between the expected utilization and actual utilization, and a tendency was noted to overrate self-reported utilization in relation to actual utilization. It is concluded that continuity of dental care and unambiguous organizational affiliation is a prerequisite for a high utilization rate, but it also seems that the outreaching work done by the child dental health service is effective with regard to utilization.
Utilization of dental services among three groups of young adults was studied longitudinally. Each year from age 16 to age 19, participants were defined as users or non-users of alternative dental programs. Dental programs were taking place with public dental health service clinics (n = 386), with private dental practitioners, free of charge (n = 161), and with private dental practitioners, partially reimbursed by health insurance (n = 261). The paper analyzes whether the pattern of utilization of the last two groups might be described by a Markovian model defining use or non-use of dental care each of 3 years as two mutually exclusive Markovian states. Contingency table analysis of the relationships of the utilization status and sex, social group, and delivery program showed that the utilization pattern could not be described by a Markovian model. Conversely, strong relationships between 1-yr user status and 3-yr user status was found. Implications in relation to the prevailing dental health care policy emphasizing regular dental care and continuity between child dental health care and young adult dental programs are discussed.