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Biomedical subjects

G Koch

Publications and source records attributed to G Koch.

At least 145 records · Page 8Linked to original sources

Immunogenic and protective properties of chicken anaemia virus proteins expressed by baculovirus.

The coding information for three putative chicken anaemia virus proteins (VP1, VP2, VP3) was inserted into a baculovirus vector and expressed in insect cells. The immunogenic properties of the chicken anaemia virus (CAV) proteins produced separately or together in insect-cell cultures were analysed by inoculating them into chickens. Only lysates of insect cells which have synthesised equivalent amounts of all three recombinant CAV proteins or cells which synthesised mainly VP1 plus VP2 induced neutralising antibodies directed against CAV in inoculated chickens. Progeny of those chickens were protected against clinical disease after CAV challenge. Inoculation of a mixture of lysates of cells that were separately infected with VP1-, VP2- and VP3-recombinant baculovirus did not induce significant levels of neutralising antibody directed against CAV and their progeny were not protected against CAV challenge. Our results indicate that expression in the same cell of at least two CAV proteins, VP1 plus VP2, is required to obtain sufficient protection in chickens. Therefore, recombinant CAV proteins produced by baculovirus vectors can be used as a sub-unit vaccine against CAV infections.

Animals↗

Psychophysical responses to a speech stressor: correlation of plasma beta-endorphin levels at rest and after psychological stress with thermally measured pain threshold in patients with coronary artery disease.

OBJECTIVES: We tested the hypothesis that psychological stress alters plasma levels of opioid peptides and that these plasma levels are related to pain perception in patients with coronary artery disease. BACKGROUND: Public speaking psychological stress has previously been shown to be associated with silent ischemia. METHODS: After instrumentation and a 30-min rest period, venous blood samples for beta-endorphin were obtained before and immediately after psychological stress in 20 patients with coronary artery disease. Pain threshold was then assessed using a thermal probe technique at baseline and immediately after stress. Patients gave three brief speeches lasting a total of 15 min about real-life hassle situations. RESULTS: Psychological stress significantly increases plasma beta-endorphin levels (4.3 +/- 0.9 pmol/liter [mean +/- SE] at rest to 8.3 +/- 2 pmol/liter after stress, p < 0.05). There was a significant positive correlation between pain threshold and beta-endorphin levels after stress (r = 0.577, p = 0.008). This significant positive correlation was still present while rest blood pressure and change in blood pressure during stress were controlled for by analysis of covariance techniques. CONCLUSIONS: In patients with coronary artery disease and exercise-induced ischemia, public speaking produces psychological stress manifested by increased cardiovascular reactivity and causes an increase in plasma beta-endorphin levels that is significantly correlated with pain thresholds. These findings may explain the predominance of silent ischemia during psychological stress in patients with coronary artery disease.

Blood Pressure↗

Evaluating Alzheimer's special care units: reviewing the evidence and identifying potential sources of study bias.

Special Care Units (SCUs) for Alzheimer's disease have been proliferating in long-term care, but their effectiveness remains unproven. This review summarizes the published studies, presents and discusses the many potential sources of bias that pose special problems for SCU research, and proposes strategies for conducting and interpreting future outcome studies in this difficult research setting.

Aged↗

Dental caries and prolonged breast-feeding in 18-month-old Swedish children.

Three thousand children aged 18 months were screened for dental caries and ongoing breast-feeding at 46 child welfare centres in different parts of Sweden. Of these, 200 children were selected for a more comprehensive examination, involving investigation of dietary, toothbrushing and sucking habits, use of fluoride, and determination of salivary levels of mutans streptococci and lactobacilli. The children were divided into four groups: group 1: children with caries not being breast-fed; group 2: children with caries being breast-fed; group 3: caries-free children being breast-fed; group 4: caries-free gender- and age-matched reference children not being breast-fed. The results showed that 63 of the children (2.1%) had caries and 61 (2.0%) were still being breast-fed. Twelve (19.7%) of the 61 children still being breast-fed had caries compared with 51 (1.7%) of the 2939 children not being breast-fed; the difference was statistically significant. Children with caries and still being breast-fed had a mean defs of 5.3, and those with caries not being breast-fed 4.9; the difference was not statistically significant. Children with caries, irrespective of whether they were being breast-fed or not, had significantly higher numbers of cariogenic food intakes per day than caries-free children. Mutans streptococci were detected in 67% of the children and lactobacilli in 13%. Children with detectable mutans streptococci and lactobacilli had significantly more caries than those without. The results indicate that Swedish children with prolonged breast-feeding have a tendency to establish unsuitable dietary habits which constitutes a risk situation for developing caries at an early age.

Age of Onset↗

Assessment of risk for periodontal disease. II. Risk indicators for alveolar bone loss.

This study examined the risk indicators for alveolar bone loss associated with periodontal infection. A cross-section of 1,361 subjects aged 25 to 74 years, from Erie County, NY were evaluated for interproximal alveolar bone loss and potential explanatory variables including age, gender, history of systemic diseases, smoking, and presence of 8 subgingival bacteria. Interproximal alveolar bone loss was measured from the alveolar crest to the CEJ and a mean computed for each subject. The mean bone loss per subject (BL) ranged from 0.4 to 8.8 mm, and this outcome variable was grouped into 4 ordered categories. The degree of association between the explanatory variables and BL was examined utilizing an ordinal stepwise logistic regression model. Factors which were positively associated with more severe bone loss included subgingival colonization with B. forsythus (O.R. 2.52; 95% CI: 1.98 to 3.17) or P. gingivalis (O.R. 1.73; 95% CI: 1.27 to 2.37), race (Native American, Asian, or Pacific Islanders) with an O.R. 2.40 (95% CI: 1.21 to 4.79), and gender with males having higher odds than females. Smokers had greater odds for more severe bone loss compared to non-smokers ranging from 3.25 (95% CI: 2.33 to 4.54) to 7.28 (95% CI: 5.09 to 10.31) for light and heavy smokers, respectively. Individuals at older ages also showed more severe levels of bone loss. History of kidney disease (O.R. 0.55; 95% CI: 0.35 to 0.89) and history of allergies (O.R. 0.76; 95% CI: 0.59 to 0.98) were inversely associated with severity of bone loss.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

The effect of a low fluoride containing toothpaste on the development of dental caries and microbial composition using a caries generating model device in vivo.

The purpose of the study was to evaluate the effect of daily use of a low fluoride containing toothpaste (250 ppm F) on the uptake of fluoride and development of enamel lesions as well as the prevalence of lactobacilli and mutans streptococci in dental plaque compared to the use of placebo toothpaste. 16 children were selected with homologous premolar teeth. The teeth were cemented with orthodontic bands ad modum Ogaard for plaque accumulation and enamel lesion development. The plaque accumulated during 4 weeks was collected and analysed for lactobacilli and mutans streptococci. The teeth were further analysed by secondary ion mass spectrometry (SIMS), determining the concentration profiles of fluoride and other elements in the outermost enamel and in the lesion. The results show that although significant amounts of fluoride were taken up in the surface enamel from the fluoride toothpaste, the extent of the lesions was not influenced compared to teeth brushed with a non F-toothpaste. Neither were microbiological differences in the dental plaque found between the groups. An interesting observation was that early demineralization of enamel took place without detectable levels of mutans streptococci in the overlaying dental plaque. The conclusion is that fluoride taken up in enamel from F-toothpaste has no significant influence on enamel lesion development if a cariogenic dental plaque with high levels of acid producing microorganisms is continuously attached to the enamel surface.

Adolescent↗

Children's dental health in Europe. Clinical calibration of dental examiners in eight EU countries.

An epidemiological investigation has been initiated from Sweden with the aim to study and compare dental health, dental treatment needs and attitudes to dental care in two well-defined age-groups, children of 5 and 12 years of age, in eight EU countries. To ensure comparability of the clinical registrations, data collection was preceded by clinical calibrations of the examiners from the participating countries. All the examiners participated in a workshop with initial calibration exercises. Agreement, expressed as sensitivity, was measured between the Swedish examiner acting as the reference examiner and each of the other examiners in turn, and assessed separately for the two age-groups. For DMFS/dmfs, agreement ranged from 44.3% to 82.2%. These results were discussed and where necessary the criteria were modified and/or made more stringent, so that they were clearcut and could be adhered to consistently. In a second calibration between the Swedish and the national examiner undertaken in each of the seven countries, the inter-examiner agreement (sensitivity) varied between 85.4% and 100%. The mean sensitivity for DMFS/dmfs after the total calibration procedures was 89.5% for the 12-year olds and 91.7 for the 5-year olds. The mean sensitivity for both age-groups together was 90.6% and the corresponding value for specificity was 98.9%.

Age Factors↗

Oral health of individuals aged 3-80 years in Jönköping, Sweden in 1973, 1983, and 1993. I. Review of findings on dental care habits and knowledge of oral health.

The aim of the present study was to compare data on dental care habits and knowledge of oral health in three cross-sectional studies carried out in 1973, 1983, and 1993. The 1973 study constituted a random sample of 1000 individuals evenly distributed in the age groups 3, 5, 10, 15, 20, 30, 40, 50, 60, and 70 years. The same age groups with addition of a group of 80-year-olds were included in the 1983 and 1993 studies which comprised 1104 and 1078 individuals, respectively. A questionnaire (23-101 questions) about dental care habits and knowledge of oral health was used in connection with a clinical and radiographic examination. The same questions were used in all the three studies. An addition to the 1993 investigation was questions concerning ethnographic background. In 1993 approximately 95% of all individuals were visiting the dentist on a regular basis every or every second year. The 30-year-olds, however, did not visit a dentist as regularly in 1993 as in 1983. The 70- and 80-year-olds visited a dentist more regularly in 1993 than in 1983. An increased number of adults in all age groups, except for the 70-year-olds, received their dental care in the Public Dental Service in 1993 compared to 1983 and 1973. Most 40-year-olds and older, however, received their dental care by private practitioners. About 80% of all adults in 1993 were enrolled in a recall system on the dentist's initiative while in 1973 most appointments were based on the patient's own initiative. The number of individuals who felt discomfort at the prospect of an appointment with the dentist was more or less the same in 1973, 1983, and 1993. The knowledge of the etiology of dental diseases has not changed much between 1973 and 1993. The frequency of toothbrushing has increased since 1973 and in 1993 more than 95% of all individuals brushed their teeth daily. The use of dental floss and toothpicks as well as disclosing tablets decreased in 1993 compared to 1983. Almost all individuals in 1993 used fluoride toothpaste. The use of topical fluorides and fluoride tablets in children had decreased considerably in 1993 compared to 1983.

Adolescent↗

Oral health of individuals aged 3-80 years in Jönköping, Sweden in 1973, 1983, and 1993. II. Review of clinical and radiographic findings.

The aim of this epidemiological study was to analyse various clinical and radiographic data on oral health and compare the results to those of two cross-sectional studies carried out in 1973 and 1983. In 1973, 1983, and 1993 a random sample of 1000, 1104, and 1078 individuals, respectively were studied. The individuals were evenly distributed in the age groups 3, 5, 10, 15, 20, 30, 40, 50, 60, and 70 years. In 1983 and 1993 80-year-olds were also included. All subjects were inhabitants of the community of Jönköping, Sweden. The clinical and radiographic examination assessed edentulousness, removable dentures, implants, number of teeth, caries, restorations and overhangs, oral hygiene, calculus, periodontal status, endodontic treatment, and periapical status. The number of edentulous individuals was reduced by half from 1973 to 1993 and is now 8% in the age groups 40-70 years. The mean number of teeth has increased and up to the age of 50 years the individuals had more or less complete dentitions. During the 20-year period there was generally decreasing number of carious lesions and restorations. In the 15- and 20-year-olds, however, there was an increasing number of decayed/filled tooth surfaces in 1993 compared to 1983. Furthermore, after the age of 50 there was an increase in number of restored tooth surfaces. As regards secondary caries there was an increase for the 10- and 15-year-olds between 1983 and 1993. For all other age groups there were only minor differences. Generally restorations exhibited a high quality and 85-90% had no proximal overhangs. In 1973 this figure was about 60%. Concerning the frequency of tooth surfaces exhibiting plaque and gingival inflammation there was a considerable decrease from 1973 to 1983, but during the period from 1983 to 1993 there seems to be no improvement. In some age groups there was even a significant increase in plaque (15-year-olds) and gingivitis (3-, 5-, 15-, 20-, and 60-year-olds). The frequency of individuals with one or more periodontal pockets (> 4 mm) increased with age. In 1993 the bone level at the age of 40 years corresponded to the bone level at the age of 20 years in 1973. The percentage of endodontically treated teeth was lower in 1993 in all age groups than in 1973 and 1983. The percentage of endodontically treated teeth with periapical or juxtaradicular destructions was unchanged in all three studies. The comparison of the three studies from 1973, 1983, and 1993 shows that there has been a great improvement in oral health over this 20-year period. In 1993, however, the increasing number of decayed/filled tooth surfaces in the 15- and 20-year-olds and an increase in plaque and gingivitis in some younger age groups calls for special attention.

Adolescent↗

Identification of the promoter region of chicken anemia virus (CAV) containing a novel enhancer-like element.

The single promoter region in the cloned genome [Noteborn et al., J. Virol. 65 (1991) 3131-3139] of chicken anemia virus (CAV) in chicken T-cells was analysed via CAT assays. A unique region containing four or five near-perfect direct repeats (DR) of 21 bp with one 12-bp insert was proven to be the main transcription-activation element, with enhancer-like characteristics. PCR studies revealed that CAV isolates from across the world all contained this promoter sequence. Electrophoretic mobility-shift assays (EMSA) showed that individual DR units, as well as the 12-bp insert, can bind to nuclear factors of chicken T-cells. Competition assays revealed that the DR units bound to factors other than the 12-bp insert. A synthetic oligodeoxyribonucleotide containing an SP1-box (5'-GGGCGG) could compete with factors binding to the 12-bp insert. Purified human SP1 was shown to have very strong affinity for the 12-bp insert.

Animals↗

ADP-ribosylation of the GTP-binding protein Rho by Clostridium limosum exoenzyme affects basal, but not N-formyl-peptide-stimulated, actin polymerization in human myeloid leukaemic (HL60) cells.

Treatment of human myeloid leukaemic (HL60) cells with Clostridium limosum exoenzyme, which inactivates the small GTP-binding protein Rho by ADP-ribosylation, decreased the basal F-actin content. Inhibition of F-actin occurred after long-term treatment (24 h) of intact HL60 cells or after introduction of the toxin by electropermeabilization in a toxin-concentration-dependent manner. Concomitantly with the decrease in the basal F-actin content, the GTP-binding protein Rho was ADP-ribosylated in intact cells. However, Clostridium limosum toxin had no inhibitory effect on N-formyl-peptide-induced actin polymerization. Moreover, the relative N-formyl-peptide-stimulated polymerization was substantially enhanced in cells treated with Clostridium limosum transferase. In contrast with Clostridium limosum exoenzyme, component C21 of the Clostridium botulinum C2 toxin, which ADP-ribosylates G-actin, depolymerized basal F-actin and inhibited N-formyl-peptide-induced actin polymerization in electropermeabilized HL60 cells. These findings indicate that Rho proteins are involved in the basal, but not the ligand-evoked, actin polymerization in HL60 cells.

ADP Ribose Transferases↗

Differences in clot lysis among patients demonstrated in vitro with three thrombolytic agents (tissue-type plasminogen activator, streptokinase and urokinase).

This study compares the ability of 3 thrombolytic drugs to promote clot lysis using a new in vitro testing procedure. Whole blood samples from 132 patients were tested using 5 different concentrations of tissue-type plasminogen activator (t-PA), streptokinase (SK) and urokinase. A mixture of blood and thrombolytic drug was placed on a dry-reagent test card containing reptilase, buffers and paramagnetic particles where clot formation occurred. Analysis of the motion of the clot-embedded paramagnetic particles caused by an oscillating magnetic field was used to define the lysis onset time. The slope of the linear regression plot of lysis onset time versus 1/[drug concentration] defined the kinetic rate constant (k) for each drug in each patient. Higher values of k indicated greater resistance to in vitro clot lysis. In the patients studied, there was a large range of k values for t-PA and SK (coefficient of variation 143 and 137%, respectively) but a smaller range of k for urokinase (coefficient of variation 32%). The coefficients of variation for t-PA and SK observed in the study group were five- to 10-fold greater than the coefficients of variation determined for replicate test measurements. Resistance to all SK concentrations tested was found in 9% of the patients. In vitro sensitivity to thrombolysis was compared among the drugs by correlating the derived k values. These comparisons indicated no relation for any of the drugs; many patients had a relatively low k value for 1 drug, while having a relatively high k value for a different drug.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Coagulation Tests↗

Thrombolytic treatment and balloon angioplasty in chronic occlusion of the aortic bifurcation.

OBJECTIVE: To evaluate nonsurgical alternatives in reopening chronically occluded aortic bifurcation. DESIGN: Uncontrolled randomized study. SETTING: University-affiliated referral center for vascular diseases. PATIENTS: Twenty-five of 39 consecutive patients with chronic aortoiliac disease including a totally occluded aortic bifurcation were found to be acceptable candidates for an aortobifemoral prosthetic graft. INTERVENTION: Patients were randomly assigned to receive either streptokinase or urokinase or recombinant tissue-type plasminogen activator (rt-PA). In cases of successful thrombolysis and residual obstructions, subsequent balloon angioplasty was attempted. Prosthetic bypass grafting was done if thrombolytic treatment and balloon angioplasty failed. RESULTS: Complete lysis was achieved in 5 of 25 patients (20%). In 10 (40%) patients, lysis showed residual obstructions, which were reopened mechanically in 8 patients; 2 patients had extra-anatomical bypass grafts. Ten patients (40%) without thrombolysis had surgical aortobifemoral bypass grafts. Overall, recanalization and clinical improvement were achieved in 13 of 25 patients (52%) by thrombolytic therapy and subsequent balloon angioplasty. The recanalization rate did not differ among the different thrombolytic drugs. However, rt-PA therapy resulted in reopening after 4 days of treatment; streptokinase, after 6 days; and urokinase, after 9 days (P < 0.005). No major complications or deaths occurred. CONCLUSION: Thrombolytic treatment followed by balloon angioplasty may help avoid the need for aorto-bifemoral prosthetic bypass grafting in more than 50% of patients with chronic aortoiliac disease.

Adult↗

Completeness of prescription recording in outpatient medical records from a health maintenance organization.

Since validity of drug data is often characterized by the agreement between questionnaire and medical record data, medical record completeness for drug therapy was evaluated. Outpatient medical records of 501 randomly selected Group Health Cooperative Health Maintenance Organization (HMO) participants known to have been dispensed a non-steroidal anti-inflammatory drug (NSAID) were reviewed for completeness. Documentation was also evaluated for indication, age, gender, location of visit, and number of visits. The NSAID was recorded in 89% of the charts reviewed. Charts with a vague/missing diagnosis were more likely to lack documentation [RR (95% CI): 20.0 (13.2-30.3)]. The data suggested that poorer documentation was related to older age [1.5 (0.9-2.5)] but not to gender, indication, location of visit, or number of visits. Presence of an indication was positively correlated to the completeness of drug documentation. According to this staff/group HMO, there may be a higher concordance between self-reported medication use and medical record data than found in previous literature.

Age Factors↗

Oral hygiene in relation to caries development and immigrant status in infants and toddlers.

The purpose of this study was to describe oral hygiene factors in infants and toddlers living in Sweden with special reference to caries prevalence at 2 and 3 yr of age and to immigrant status. The study was designed as a prospective, longitudinal study starting with 671 children aged 1 yr. At 3 yr, all the children were invited to a further examination. A total of 298 children, randomly selected from the original group, were also examined at 2 yr. The accompanying parent was interviewed about the child's oral health habits. Children who were free of caries at 3 yr had had their teeth brushed more frequently at 1 and 2 yr of age, had used fluoride (F)-toothpaste more often at 2 yr of age, and had a lower prevalence of visible plaque at 1 and 2 yr of age than children with caries. Immigrant children had had their teeth brushed less frequently, had used less F-toothpaste, and had a higher prevalence of visible plaque at 1 yr of age than nonimmigrant children. Early establishment of good oral hygiene habits and regular use of F-toothpaste seem to be important for achieving good oral health in pre-schoolchildren.

Child, Preschool↗

A single chicken anemia virus protein induces apoptosis.

Chicken anemia virus (CAV) causes cytopathogenic effects in chicken thymocytes and cultured transformed mononuclear cells via apoptosis. Early after infection of chicken mononuclear cells, the CAV-encoded protein VP3 exhibits a finely granular distribution within the nucleus. At a later stage after infection, VP3 forms aggregates. At this point, the cell becomes apoptotic and the cellular DNA is fragmented and condensed. By immunogold electron microscopy VP3 was shown to be associated with apoptotic structures. In vitro, expression of VP3 induced apoptosis in chicken lymphoblastoid T cells and myeloid cells, which are susceptible to CAV infection, but not in chicken embryo fibroblasts, which are not susceptible to CAV. Expression of a C-terminally truncated VP3 induced much less pronounced apoptosis in the chicken lymphoblastoid T cells.

Amino Acid Sequence↗

Effect of acute magnesium administration on the frequency of ventricular arrhythmia in patients with heart failure.

BACKGROUND: There is a high incidence of ventricular arrhythmia and sudden death in patients with heart failure. Unfortunately, currently available antiarrhythmic agents have only limited efficacy and may result in proarrhythmia and hemodynamic deterioration in these patients. METHODS AND RESULTS: We studied the acute effect of intravenous magnesium chloride on the frequency and severity of ventricular arrhythmia in 30 patients with symptomatic heart failure using a double-blind, placebo-controlled crossover design. The left ventricular ejection fraction was 23.0 +/- 8.0% (mean +/- SD). No patient had a history of symptomatic ventricular arrhythmia or was receiving antiarrhythmic agents, calcium channel antagonists, or beta-blockers. Patients were randomized to receive placebo (5% dextrose [D5W] in water alone) or magnesium chloride in D5W given as a bolus of 0.3 mEq/kg over 10 minutes followed by a maintenance infusion of 0.08 mEq/kg per hour for 24 hours. The magnesium concentrations 30 minutes and 24 hours after the bolus were 3.6 +/- 0.1 and 4.2 +/- 0.1 mg/dL, respectively. There was no significant change in serum potassium concentration during magnesium administration. Blinded analysis revealed that administration of intravenous magnesium chloride, compared with placebo, significantly decreased total ventricular ectopy per hour (mean +/- SEM, 70 +/- 26 versus 149 +/- 64, P < .001), couplets per day (23 +/- 11 versus 94 +/- 59, P = .007), and episodes of ventricular tachycardia per day (0.8 +/- 0.2 versus 2.6 +/- 1.0, P = .051). CONCLUSIONS: Intravenous magnesium chloride administration reduces the frequency of ventricular arrhythmia in patients with symptomatic heart failure.

Adult↗

Assessment of risk for periodontal disease. I. Risk indicators for attachment loss.

Specific risk indicators associated with either susceptibility or resistance to severe forms of periodontal disease were evaluated in a cross-section of 1,426 subjects, 25 to 74 years of age, mostly metropolitan dwellers, residing in Erie County, New York, and surrounding areas. The study sample exhibited a wide range of periodontal disease experience defined by different levels of attachment loss. Therefore, it was possible to accurately assess associations between the extent of periodontal disease and patient characteristics including age, smoking, systemic diseases, exposure to occupational hazards, and subgingival microbial flora. Age was the factor most strongly associated with attachment loss, with odds ratios for subjects 35 to 44 years old ranging from 1.72 (95% CI: 1.18 to 2.49) to 9.01 (5.86 to 13.89) for subjects 65 to 74 years old. Diabetes mellitus was the only systemic disease positively associated with attachment loss with an odds ratio of 2.32 (95% CI: 1.17-4.60). Smoking had relative risks ranging from 2.05 (95% CI: 1.47-2.87) for light smokers increasing to 4.75 (95% CI: 3.28-6.91) for heavy smokers. The presence of two bacteria, Porphyromonas gingivalis and Bacteroides forsythus, in the subgingival flora represented risks of 1.59 (95% CI: 1.11-2.25) and 2.45 (95% CI: 1.87-3.24), respectively. Our results show that age, smoking, diabetes mellitus, and the presence of subgingival P. gingivalis and B. forsythus are risk indicators for attachment loss. These associations remain valid after controlling for gender, socioeconomic status, income, education, and oral hygiene status expressed in terms of supragingival plaque accumulation and subgingival calculus. Longitudinal, intervention, and etiology-focused studies will establish whether these indicators are true risk factors.

Adult↗