Biomedical subjects

G Koch

Publications and source records attributed to G Koch.

At least 91 records · Page 5Linked to original sources

PubMed1999

Application of generalized estimating equations to a dental randomized clinical trial.

Longitudinal data present statistical problems of interest in clinical trials and epidemiologic studies. In this article, we consider a dental clinical trial in which the outcome measurements are taken on each subject at two follow-up times, and the primary interest is in the dependence of the outcome variable on covariates. The common data structure of these studies is the presence of an intraclass or serial correlation within primary sampling units or subjects. Recently generalized linear models have had extensions to methods for generalized estimating equations that take correlations within primary sampling units into account. We review and apply the Liang-Zeger methodology to a dental clinical trial. In this study, 109 adult male and female volunteers with pre-existing dental plaque were randomized to two mouth rinses (A and B) or a control mouth rinse with double blinding. The major research question in this analysis was: Are the two experimental mouth rinses more effective than the control mouth rinse in inhibiting the development of dental plaque? And if so, what is the effect of baseline plaque measurement?

Adult↗

PubMed1999

Rescue of Newcastle disease virus from cloned cDNA: evidence that cleavability of the fusion protein is a major determinant for virulence.

A full-length cDNA clone of Newcastle disease virus (NDV) vaccine strain LaSota was assembled from subgenomic overlapping cDNA fragments and cloned in a transcription plasmid between the T7 RNA polymerase promoter and the autocatalytic hepatitis delta virus ribozyme. Transfection of this plasmid into cells that were infected with a recombinant fowlpoxvirus that expressed T7 RNA polymerase, resulted in the synthesis of antigenomic NDV RNA. This RNA was replicated and transcribed by the viral NP, P, and L proteins, which were expressed from cotransfected plasmids. After inoculation of the transfection supernatant into embryonated specific-pathogen-free eggs, infectious virus derived from the cloned cDNA was recovered. By introducing three nucleotide changes in the cDNA, we generated a genetically tagged derivative of the LaSota strain in which the amino acid sequence of the protease cleavage site (GGRQGR downward arrowL) of the fusion protein F0 was changed to the consensus cleavage site of virulent NDV strains (GRRQRR downward arrowF). Pathogenicity tests in day-old chickens showed that the strain derived from the unmodified cDNA was completely nonvirulent (intracerebral pathogenicity index [ICPI] = 0.00). However, the strain derived from the cDNA in which the protease cleavage site was modified showed a dramatic increase in virulence (ICPI = 1.28 out of a possible maximum of 2.0). Pulse-chase labeling of cells infected with the different strains followed by radioimmunoprecipitation of the F protein showed that the efficiency of cleavage of the F0 protein was greatly enhanced by the amino acid replacements. These results demonstrate that genetically modified NDV can be recovered from cloned cDNA and confirm the supposition that cleavage of the F0 protein is a key determinant in virulence of NDV.

Amino Acid Sequence↗

PubMed1999

Oral health in pre-school children living in Sweden. Part III--A longitudinal study. Risk analyses based on caries prevalence at 3 years of age and immigrant status.

A decreasing proportion of children require operative treatment each year and an increasing proportion of children will at recall require no operative care. This would provide resources to give individualised prevention to children at risk for developing new carious lesions. From 3 years of age, however, the prevalence of caries increases up to the age when the primary dentition exfoliates, even though the children attend regular dental service programmes yearly, and for some children dental caries remains a significant problem. The purpose of the present study was to describe the dental health of a group of 6-year-old children living in Sweden, with special reference to caries prevalence at 3 years of age and to immigrant status. At 6 years of age, 45% of the children were free of initial and manifest carious lesions in the primary cuspids and molars. The mean caries increment between 3 and 6 years was 0.9 tooth surfaces for children who were caries free at 3 years of age compared to 4.5 tooth surfaces for children with manifest carious lesions at the same age. The mean caries increment from 3 to 6 years was 1.3 in the non-immigrant group and 3.6 in the immigrant group. For the majority of the children in this study, current preventive dental care seems sufficient. However, for about one-third of the children (children with carious lesions at 3 years of age and/or immigrant status), current caries preventive programme used in the Public Dental Service are inadequate.

Child↗

PubMed1999

Effect of a mouth rinse containing amyloglucosidase and glucose oxidase on recurrent aphthous ulcers in children and adolescents.

Recurrent aphthous ulcers are one of the most common painful diseases affecting the oral mucosa in children and adults. The aetiology is poorly understood and the treatment thus has for years mostly been symptomatic. However, there has been some promising methods in decreasing the frequency of aphthous ulcer episodes. One of these is the use of a dentifrice containing the combination of the enzymes amyloglucosidase and glucose oxidase (Zendium). The aim of this investigation was, in a pre-study and a double-blind, crossover study, to report if a mouth rinse containing the same enzymes was effective against aphthous ulcers. Thirty-six children and adolescents 7 to 19 years of age took part in the pre-study and thirty-three children and adolescents 7 to 19 years of age took part in the double-blind, crossover study. In both tests the mouth rinses with enzymes resulted in a significant reduction in the number of new aphthous ulcers and pain. In the double-blind, crossover test the 33 children experienced 60 episodes of new ulcers during a 6-month period, including a 3-month period with enzyme rinsings, compared to 221 episodes when rinsing with placebo solution. 55% of the children were completely free from ulcers during the enzyme solution rinsing period followed by a 3-month recovery period compared to 0% when rinsing with placebo. The study confirms earlier studies. Daily rinsing with the enzyme solution can be a recommended treatment to children and adolescents with recurrent aphthous ulcers.

Adolescent↗

PubMed1999

Class I and II posterior composite resin restorations after 5 and 10 years.

The aim of the present study was to compare and evaluate Class I- and Class II-restorations performed in two different composite posterior materials after 5 and 10 years. Both materials were introduced in 1983 and adapted to stress-bearing restorations. The only difference between the two materials was that one contained barium-aluminium silicate, which made the material radiopaque. All 137 restorations were performed according to standardized clinical procedures by two experienced clinicians and placed in premolars (59) or molars (78). Forty-five of the restorations were Class I and 92 Class II. The restorations were followed for the first 5 years according to the U. S. Public Health Service (USPHS) evaluation criteria. After 10 years an evaluation based on the documentation sent in by the patient's present dentist was made. Of the original 137 restorations, 127 could be examined after 5 years and 117 after 10 years. The evaluation showed that after 5 years, 114 of the examined restorations were in clinical function and after 10 years 92, which means 90 and 79 per cent respectively, of the restorations evaluated.

Adolescent↗

PubMed1998

Detection of Newcastle disease virus-specific antibodies in ostrich sera by three serological methods.

Sera from 211 ostriches were tested for the presence of Newcastle disease virus (NDV)-specific antibodies by the virus neutralisation test, the haemagglutination inhibition (HI) test and a recently developed avian paramyxovirus serotype 1 (PMV-1) specific monoclonal antibody blocking ELISA (b-ELISA). The virus neutralisation test was used as the reference for the estimation of the sensitivity and specificity of the b-ELISA and HI tests. Of the 211 sera, 140 contained NDV-specific neutralising antibodies, 130 were positive by the HI test and 122 by the b-ELISA. The sensitivity, specificity and predictive accuracy of the HI and b-ELISA tests relative to the virus neutralisation test were similar. The good agreement between the HI and b-ELISA test (kappa = 0.85) suggested that the two methods are interchangeable.

Animals↗

PubMed1998

[The status of perioperative pain therapy in Germany. Results of a representative, anonymous survey of 1,000 surgical clinic. Pain Study Group].

To evaluate the status of perioperative pain management we mailed a anonymous postal survey to all 2,254 surgical departments in Germany. We received answers from 1,000 clinics (44.4%) which were representative related to their regional distribution. We asked the responsible surgeons to report their organizational structure and responsibilities for treating pain patients, the significance of the problem, their methods of measuring pain, and the usage of different analgesic drugs and methods. In 47% the surgeon and the anesthesist together had responsibility for adequate postoperative pain treatment; in 33% and 14%, respectively, it was the surgeon and anesthesist alone. Only 41% knew the interdisciplinary statement on pain therapy of the Professional Societies of German Surgeons and Anaesthesists from 1992. Although the importance of postoperative pain is globally acknowledged, only 19.1% of all departments had a written concept for pain treatment. Pain was measured in only 11% of the clinics mainly by using the visual analogue scale. Most surgeons relieve pain solely with systemic drugs. Regional analgesia was used by 18% only 51% of the surgeons decide on the choice and dosage of analgesic therapy on the ward; 33% admit that pain therapy often starts after complaints of the patient. 70% of all surgeons never participated in a congress on pain. We conclude that postoperative pain management in most German surgical departments still lacks effectiveness, adequacy, and organizational and scientific background.

Analgesics↗

PubMed1998

[Endoluminal therapy of infrarenal aortic aneurysms with the Talent system--initial experiences with a new endoprosthesis].

PURPOSE: To report the early clinical experience with the Talent stent-graft system in the treatment of infrarenal aortic aneurysms. MATERIALS AND METHODS: The study group comprised 15 males aged from 51-79 years. A bifurcated Talent stent-graft was implanted in 9 patients with type B or C aneurysms, a tube graft in 6 patients with a type A aneurysm. The stent-grafts were introduced via a surgical femoral cut-down, for a bifurcated graft a bilateral surgical access was needed. All procedures were performed as teamwork by radiologists and vascular surgeons under general anaesthesia in the angiography suite. RESULTS: Primary and secondary technical successes were 80 and 86%, respectively. Technical failures were due to access site problems (n = 1; elective open repair), malpositioning of the prosthesis (n = 1; immediate conversion to open surgery), and primary distal leakage (n = 1; elective occlusion by means of distal stent-graft extension). One patient died 15 days after an uneventful stent-graft insertion (30-day mortality 6%). No complications were observed during a mean follow-up period of 7.8 months. The aneurysmal diameter decreased in 6 patients and remained unchanged in the others. CONCLUSIONS: The Talent system revealed satisfactory early results which are comparable to competitive stent-graft systems. An advantage of this stent-graft device is the availability in a wide range of dimensions. A major disadvantage is the large introducer system (french size 22-27).

Aged↗

PubMed1998

Simultaneous expression of recombinant baculovirus-encoded chicken anaemia virus (CAV) proteins VP1 and VP2 is required for formation of the CAV-specific neutralizing epitope.

Chicken anaemia virus (CAV) expresses three proteins, VP1, VP2 and VP3, but its capsid contains only the VP1 protein. In this paper, we report that for production of the neutralizing epitope, co-synthesis of (recombinant) VP1 and VP2 has to take place. We show via immunofluorescence that recombinant-baculovirus-infected Sf9 cells synthesizing VP1 (or VP2) alone react very poorly with CAV-specific neutralizing antibodies. In contrast, Sf9 cells co-infected with VP1- and VP2-recombinant baculoviruses, or infected with a single recombinant baculovirus co-expressing both VP1 and VP2, react strongly with the neutralizing antibodies. Furthermore, immunoprecipitation assays show that VP1 and VP2 interact directly with each other, which indicates that the non-structural protein VP2 might act as a scaffold protein in virion assembly. Recombinant baculovirus expressing VP1 and VP2 is, therefore, a potential production system for a subunit vaccine against CAV infection.

Animals↗

PubMed1998

Open reading frame L1 of Marek's disease herpesvirus is not essential for in vitro and in vivo virus replication and establishment of latency.

Two mutant CV1988 Marek's disease virus (MDV) strains were developed in which a part of ORF L1 was replaced by lacZ with the SV40 early promoter. These mutant strains, CVIL1LacZ-A and -B, were inoculated into chickens to test the hypothesis that ORF L1 is involved in the induction and/or maintenance of latency. Mutant virus could be reisolated from lymphocytes obtained from chickens during both the lytic and latent phase of infection, indicating that ORF L1 is not essential for the induction and/or maintenance of latency or the reactivation from latency. Beta-galactosidase-positive lymphocytes were detected during the latent infection demonstrating that the SV40 early promoter can be active in recombinant MDV strains during latent infection. Although the insertion of lacZ was stable in cell culture, recombination within lacZ and the BamHI-L fragment was observed during in vivo infection.

Animals↗

PubMed1998

Nociceptive mechanisms modulate ozone-induced human lung function decrements.

We have previously suggested that ozone (O3)-induced pain-related symptoms and inhibition of maximal inspiration are due to stimulation of airway C fibers (M. J. Hazucha, D. V. Bates, and P. A. Bromberg. J. Appl. Physiol. 67: 1535-1541, 1989). If this were so, pain suppression or inhibition by opioid-receptor agonists should partially or fully reverse O3-induced symptomatic and lung functional responses. The objectives of this study were to determine whether O3-induced pain limits maximal inspiration and whether endogenous opioids contribute to modulation of the effects of inhaled O3 on lung function. The participants in this double-blind crossover study were healthy volunteers (18-59 yr) known to be "weak" (WR; n = 20) and "strong" O3 responders (SR; n = 42). They underwent either two 2-h exposures to air or two 2-h exposures to 0. 42 parts/million O3 with moderate intermittent exercise. Immediately after post-O3 spirometry, the WR were randomly given either naloxone (0.15 mg/kg iv) or saline, whereas SR randomly received either sufentanil (0.2 microgram/kg iv) or saline. O3 exposure significantly (P < 0.001) impaired lung function. In SR, sufentanil rapidly, although not completely, reversed both the chest pain and spirometric effects (forced expiratory volume in 1 s; P < 0.0001) compared with saline. Immediate postexposure administration of saline or naloxone had no significant effect on WR. Plasma beta-endorphin levels were not related to an individual's O3 responsiveness. Cutaneous pain variables showed a nonsignificant weak association with O3 responsiveness. These observations demonstrate that nociceptive mechanisms play a key role in modulating O3-induced inhibition of inspiration but not in causing lack of spirometric response to O3 exposure in WR.

Adolescent↗

PubMed1998

Replacements of restorations in the primary and young permanent dentition.

The present study focused on the type of restorative material used and the reasons for replacements of restorations in the primary and the young permanent dentition. All patients with restorations and who were 8 and 19 years of age in 1995 and were regularly treated at 11 Public Dental Health clinics in Jönköping County, Sweden, participated in the study. Data were extracted from the records for all types of restorations in canines and molars for the preceeding of 5 years for the 8-year-olds (i.e. from 3 to 8 years of age; n = 546) and for approximal restorations in premolars and molars for the preceeding 13 years for the 19-year-olds (i.e. from 6 to 19 years of age; n = 606). In all, 6012 restorations were evaluated. The two most common restorative materials used in the primary dentition were compomer and glass ionomer cement and in the young permanent dentition composite and amalgam. In the primary dentition, 29% of the restorations had been replaced and 4% of the teeth with restorations had been extracted. Thus, 33% of the restorations in the primary dentition failed. The corresponding figure for the young permanent dentition was 13%. The most common reason for replacements in the permanent dentition was secondary caries. That restorations often fail because of caries and that the development of secondary caries is not prevented by replacement of an old restoration indicate that more attention should be paid to preventive dental care for patients with restorations in the primary as well as in the young permanent dentition.

Adolescent↗

PubMed1998

[Efficacy of an Acute Pain Service--a controlled comparative study of hospitals].

The efficacy of an acute pain service was prospectively evaluated on elective abdominal operations by comparing two surgical departments including a total of 498 patients. The patients of the clinic with an acute pain service reported less pain (at rest and in movement) pre- and postoperatively and received more analgetics. They had more appetite, lower sleep requirements and more independence. The patients' overall satisfaction was greater in the clinic with an acute pain service.

Abdomen↗

PubMed1997

Analysis of ectopic pregnancy data using marginal and conditional models.

This work is motivated by a longitudinal study of women and their ectopic pregnancy outcomes in Lund, Sweden. In this article, we review and apply the Liang-Zeger methodology to the Lund ectopic pregnancy data set. We further analyse the ectopic pregnancy data using conditional modelling approaches suggested by Rosner and Bonney. From the Lund ectopic pregnancy data, we learned that PID is the strongest predictor of subsequent development of ectopic pregnancy and that there is a monotone relationship between PID severity and ectopic pregnancy. We also learned that the presence of mycoplasma from lower or upper genital tract sites at index laparoscopy is also a strong predictor of ectopic pregnancy. Other correlates of ectopic pregnancy include age at pregnancy and history of gynaecologic surgery.

Adolescent↗

PubMed1997

Assessment of platelet activation by coronary sinus blood sampling during balloon angioplasty and directional coronary atherectomy.

Three markers of platelet activation (platelet-derived microparticles, fibrinogen binding and expression of P-selectin) were assessed by flow cytometry during diagnostic coronary angiography and therapeutic coronary interventions. In 24 patients undergoing diagnostic angiography, blood was collected to determine if our sampling techniques or coronary angiography caused platelet activation. Changes during diagnostic angiography were used to establish baseline values and interpret changes during coronary interventions. In 21 patients, blood samples were obtained at 5 time points during percutaneous transluminal coronary angioplasty (PTCA) (n = 17) or directional coronary atherectomy (DCA) (n = 4). During coronary interventions, mean values for the percentage of platelets expressing P-selectin or binding fibrinogen increased, but with considerable variation among patients. Individual responses for platelet activation markers in each patient were characterized using a twofold increase to indicate elevation related to the intervention. Patients were classified as having complicated or uncomplicated procedures based on the presence of acute closure, dissection, or thrombus observed by angiography. There were no differences in the percentage of elevated markers between patients with uncomplicated (12.5%) and complicated (19%) PTCA procedures. However, patients treated with DCA had more elevated markers (38%) than those treated with PTCA (15%) (p = 0.04). Our data suggest that the extent of platelet activation in individual patients cannot be predicted by common angiographic findings or complications. More markers of platelet activation were present after DCA and may reflect a greater degree of vascular trauma associated with this procedure.

Angioplasty, Balloon, Coronary↗

PubMed1997

Association of the Rho family small GTP-binding proteins with Rho GDP dissociation inhibitor (Rho GDI) in Saccharomyces cerevisiae.

The small GTP-binding proteins of the Rho family, consisting of the Rho, Rac, and Cdc42 subfamilies, are implicated in various cell functions, such as cell shape change, cell motility and cytokinesis, through reorganization of actin cytoskeleton. Rho GDI is a general regulator which forms a complex with the GDP-bound inactive form of the Rho family members and inhibits their activation. We have purified Rho GDI from the yeast Saccharomyces cerevisiae, cloned its gene, and named it RDII (Rho GD). In this study, we have further characterized yeast Rho GDI. Rho GDI was found in the cytosol by immunoblot and immunofluorescence microscopic analyses. Rho1p and Cdc42p were co-immunoprecipitated with Rho GDI from the cytosol. This immunoprecipitated Rho1p was mainly bound to GDP. In the disruption mutant of Rho GDI, which did not show any apparent phenotype, both Rho1p and Cdc42p were also present in the cytosol. These results indicate that yeast Rho GDI possesses properties similar to those of mammalian Rho GDI, and that there is a cytosolic factor which functionally substitutes for Rho GDI in yeast.

Fungal Proteins↗

PubMed1997

Acceptance of home and clinic-based cystic fibrosis carrier education and testing by first, second, and third degree relatives of cystic fibrosis patients.

We contacted and offered free cystic fibrosis (CF) carrier education and testing to the first, second, and third degree relatives of individuals with CF followed at a large Southeastern US CF Clinic. Relatives were offered CF carrier education and testing either in their homes or in a genetic counseling clinic. Overall, of 514 relatives offered free CF carrier education and testing, 299 (58%) accepted. Significantly more (67%) of those offered education and testing in their homes accepted than those offered education and testing in a genetic counseling clinic (45%). Regression analyses identified several factors, including education, income, gender, perceived chance of being a carrier, and perceived chance of having a child who is a CF carrier, as predictors of acceptance of education and testing in both home and clinic sites. A smaller set of factors was identified that predicted acceptance of education and testing unique to each site. Within the limits of this study and its design, even when CF carrier testing is offered free of charge, including education and testing in the home, acceptance of education and testing, while higher than in general population samples, is not universal among at-risk relatives. Several factors which may have contributed to the observations reported in this study are discussed.

Adolescent↗

PubMed1997

Alterations in receptor activation and divalent cation activation of agonist binding by deletion of intracellular domains of the glucagon receptor.

Deletion of residues 252-259 within the putative second intracellular loop of the human glucagon receptor results in a protein with high affinity for glucagon but with attenuated agonist activation of adenylyl cyclase. The Delta252-259 mutant has 4-fold higher affinity for glucagon than does the wild type receptor. The nonhydrolyzable GTP analog, guanosine 5'-(beta, gamma-imido)triphosphate (Gpp(NH)p), inhibits binding of 125I-glucagon to the wild type receptor but not to the Delta252-259 mutant. Divalent cations such as MgCl2 and CaCl2 stimulate the binding of 125I-glucagon to the wild type receptor by increasing glucagon affinity. The rate of dissociation of 125I-glucagon is decreased 4-fold by MgCl2 and increased 6-fold by Gpp(NH)p. However, divalent cations do not affect the binding of 125I-glucagon to the Delta252-259 mutant. The rate of dissociation of 125I-glucagon from the Delta252-259 mutant protein is equivalent to the rate of dissociation from the wild type receptor in the presence of MgCl2. These data suggest that at least three conformations of the glucagon receptor can exist in the membrane based on their differing affinities for 125I-glucagon. Deletion of residues 252-259 appears to lock the protein in the conformation promoted by divalent cations and prevents the protein from normal coupling to Gs.

Amino Acid Sequence↗