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Biomedical subjects

G Koch

Publications and source records attributed to G Koch.

At least 163 records · Page 9Linked to original sources
PubMed1994

Craniomandibular disorders in children--a critical review of the literature.

Reports of prevalences of craniomandibular disorders (CMD) in children and adolescents differ markedly from one study to another. Therefore it is almost impossible to get a clear picture of the magnitude of the disorder in a child population. The aim of this study was to critically compare and analyse the results presented in recent publications in order to get a comprehensive view of the prevalence of CMD in children and adolescents. Fourty epidemiological studies on CMD symptomatology and headache in the age group three to 25 years were included. Eight symptoms and eight signs were chosen for further comparisons and analyses. The prevalences of these signs and symptoms were evaluated and classified according to a set of criteria, in either frequency of "greater clinical relevance" or frequency of "lesser clinical relevance". The evaluation was based on the presented examination methods, definitions and symptom criteria used in the studies. The reported frequencies for the sixteen signs and symptoms are presented graphically. The diagram clearly show great variation in the reported frequencies for most signs and symptoms. If only reported frequencies of "greater clinical relevance" are considered, these variations are less pronounced but still considerable. One major reason for this is inter- and intraindividual variation among the examiners. Another plausible and often overlooked reason is the fact that examination methods designed for adults uncritically have been applied on children without consideration of age and cognitive development of the child.

Adolescent↗
PubMed1993

Enhancement of Clostridium botulinum C3-catalysed ADP-ribosylation of recombinant rhoA by sodium dodecyl sulfate.

The influence of sodium dodecyl sulfate (SDS) on ADP-ribosylation by Clostridium botulinum C3 exoenzyme (C3) was studied. SDS increased the ADP-ribosylation of recombinant rhoA and human platelet cytosolic proteins maximally at 0.01% whereas higher concentrations of the detergent (> 0.01%) inhibited the ADP-ribosylation. In contrast, ADP-ribosylation of human platelet membranes and of recombinant rhoB was inhibited by the detergent. The Km for NAD of the ADP-ribosylation of rhoA was decreased by SDS from about 10 to 0.6 microM. Whereas in the absence of SDS, the C3-induced ADP-ribosylation of recombinant rhoA is not affected by the amphiphilic wasp venom mastoparan, in the presence of SDS (0.01%) mastoparan (100 microM) inhibited the ADP-ribosylation. C3-associated NAD-glycohydrolase activity was maximally and half-maximally inhibited by 0.1 and 0.013% SDS, respectively. Inhibition of NAD-glycohydrolase activity was reversed by diluting out SDS indicating that C3 was not irreversibly denatured by SDS treatment. SDS (0.01%) completely inhibited the [3H]GTP binding of rhoA whereas the release of previously bound nucleotide was not affected. The data indicate that changes in the lipophilicity of rhoA protein largely affect its ability to serve as a substrate for C3-like ADP-ribosyltransferases.

ADP Ribose Transferases↗
PubMed1993

A stochastic model for cell debris in flow cytometry.

An important problem in analyzing flow cytometry DNA measurements, especially for tumor samples, is the presence of background noise, mainly resulting from cellular debris. Several models have been proposed for subtracting this contribution from DNA content histograms. In the present paper we propose a model for background debris distribution based on a specific mechanism for the DNA fragmentation process of the cell nucleus. In particular, we suggest that the fragmentation is more likely to occur in the sites which are closer to the end points of the DNA chain. This accounts for the observed higher frequency of small-sized fragments in experimental DNA distribution. The proposed model depends on two parameters describing the intensity and the shape of the background. It has been successfully validated against four series of experimental data of DNA distribution with increasing level of background.

Cell Fractionation↗
PubMed1993

Local antibody forming cell responses to the Hitchner B1 and Ulster strains of Newcastle disease virus.

The Hitchner B1 and Ulster strains of Newcastle disease virus (NDV) replicated to high titre in the Harderian gland (HG) after eye-drop infection. The Harderian gland then became the major site of antiviral IgA-antibody-forming cells (AFC) in the body and their number correlated to the level of antiviral IgA antibody in the tears. The spleen, HG and femoral bone marrow all contained comparable levels of antiviral IgG-AFC and IgM-AFC after two intra-ocular inoculations of virus, whereas the caecal tonsil and bursa contained few AFC despite the local replication of the Ulster strain of NDV leading to high titres of virus in the faeces. Vaccines of the Hitchner B1 strain of NDV were much less effective at inducing antibody by the intranasal compared with intra-ocular route and no virus was re-isolated after intranasal vaccination. The intravenous inoculation of inactivated Iscoms of NDV could stimulate the spleen, but not the Harderian gland to the same extent as a live virus.

Animals↗
PubMed1993

The actions of RFamide neuroactive peptides on the isolated heart of the giant African snail, Achatina fulica.

1. The effects of a range of RFamide peptides were examined on the frequency, amplitude and tone of the isolated heart of Achatina fulica. 2. FMRFamide, FLRFamide and SDPNFLRFamide were potent excitants while LPLRFamide, KHEYLRFamide and GSFFRFamide were weak excitants. 3. DNFLRFamide and SSLFRFamide were potent inhibitory peptides while LFRFamide, GSLFRFamide and KNEFIRFamide were weak inhibitory peptides. 4. MRFamide, LRFamide and RFamide were inactive. 5. It is concluded that a tetrapeptide sequence is the minimal requirement for activity on the Achatina heart. With the exceptions of DNFLRFamide and in most preparations GSFFRFamide, LRFamide peptides are excitatory while FRFamide peptides are inhibitory. 6. Due to its inhibitory effect and high potency, the sequence DNFLRFamide warrants further investigation.

Amino Acid Sequence↗
PubMed1993

Diagnosis and treatment of carotid body tumors.

Carotid body tumors are rare although they must always remain part of the differential diagnosis of a neck mass. Sonography as the screening method of choice followed by angiography determines the diagnosis. In 11 patients 12 carotid body tumors were extirpated. The reconstruction of the internal carotid artery with an interposition of the greater saphenous vein was necessary in two cases after resection of the tumor. One patient underwent preoperative embolisation because of a huge tumor. Two postoperative radiotherapies were undertaken because of malignancy in one case and a partially extirpated tumor in the other. After a 9 year follow-up period all patients are alive. One patient suffers from a persistent palsy of the hypoglossal nerve and another complains of permanent headache supposedly caused by the reocclusion of the venous interposition of the carotid artery. In conclusion, our data support the diagnostic strategies in patients with suspected carotid body tumors. Regarding the exact therapeutic regimen, we suggest the surgical resection, followed by radiotherapy in cases of confirmed malignancy or partially resectable lesions.

Adult↗
PubMed1993

Inactivation of chicken anaemia virus in chickens by heating and fermentation.

The transmission of pathogenic microorganisms such as viruses by the use of animal products in animal feed constitutes a potential risk to the health of livestock. To reduce the risk, it is necessary to understand the survival of viruses during the processing of animal products to feed-stuffs. Since chicken anaemia virus (CAV) is very resistant to inactivation, we used it as a model for the inactivation of pathogenic viruses during treatment of animal products. It is concluded that fermentation of CAV viraemic tissue did not affect the inactivation of CAV, however, heating at a core temperature of 95 degrees C for 30 min or 100 degrees C for 10 min is sufficient to inactivate CAV. Compared with the conditions for inactivation reported in the literature for other pathogenic viruses, our treatment is more stringent. CAV viraemic chickens are thus suitable as a model to test the heat inactivation of pathogenic viruses.

Animal Feed↗
PubMed1993

Short report: ramipril and hydrochlorothiazide combination therapy in hypertension: a clinical trial of factorial design. The East Germany Collaborative Trial Group.

OBJECTIVE: To identify appropriate dosages of ramipril and hydrochlorothiazide (HCT) when given in combination once a day for the treatment of essential hypertension. DESIGN: A 2- or 4-week placebo run-in followed by 6-week, double-blind, parallel-group phase: 4 x 3 factorial (2.5, 5 and 10 mg ramipril; 12.5 and 25 mg HCT; all six combinations; placebo). SETTING: Office practice (21 centres). PATIENTS AND PARTICIPANTS: Patients with mild-to-moderate essential hypertension (World Health Organization stage I-II; supine diastolic blood pressure 100-115 mmHg in last 2 weeks of run-in): 581 enrolled, 534 randomly assigned to double-blind therapy and 517 completed. MAIN OUTCOME MEASURES: Reduction in supine and standing blood pressure. RESULTS: In pairwise comparisons, the combinations of 5 mg ramipril with 12.5 and 25 mg HCT and 10 mg ramipril with 12.5 mg HCT consistently produced significantly greater blood pressure reductions than their respective components. Response surface analyses were performed, and a stairstep model was constructed to characterize the shape of the dose-response surface. The combinations involving 5 and 10 mg ramipril with 12.5 and 25 mg HCT were again more effective than their components. Withdrawals and adverse effects were minimal for all treatments. A large drop in serum potassium was observed on 25 mg HCT, but not on combination therapy. Addition of ramipril appeared to reduce the hyperuricaemic effect of HCT. CONCLUSIONS: Several dosage combinations of ramipril plus HCT produced significantly greater blood pressure reductions than the monotherapies at the same dosages. Overall, the combination of 5 mg ramipril and 25 mg HCT gave the best mean reduction. Combination therapy with ramipril plus HCT was safe and effective for patients with mild-to-moderate essential hypertension.

Double-Blind Method↗
PubMed1993

The rate of periodontal attachment loss in subjects with established periodontitis.

A stepwise approach to determine attachment level changes was utilized to assess the nature of progression of periodontal disease. Following initial screening, 51 subjects with established periodontitis were monitored quarterly for 9 more months. Probing depth (PD) and relative attachment level (RAL) were recorded using an automated, pressure sensitive probe system. To establish intra-examiner error, repeated measurements were performed for all sites at the final visit. An overall standard deviation (SD) for RAL repeated measurements was initially calculated (0.76 mm) using all 6,935 double measurements. Sites were sorted by factors which contribute to the error of attachment level measurements; i.e., pocket depth (shallow, moderate, deep), tooth type (molar, non-molar) and location (buccal, lingual). Data were sorted by the above 12 groups, and SD for repeated measurements was calculated separately for them. The ratio between these SD and the overall SD served as the corrective factor. Each patient's initial threshold (2 SD) was multiplied by these corrective factors thus resulting in 12 thresholds for each subject. Next, linear, exponential and logarithmic regression models were tested for each site, and the regression model showing the highest R value was chosen for that site. AL changes were tested against the patient's threshold for that site. Sites with attachment loss exceeding the threshold were deemed active. Five hundred eighty-one sites (8.3%) exhibited attachment loss exceeding the various thresholds. Of these, linear progression occurred in 195, logarithmic in 224, and exponential in 162 sites. Individual patient's attachment loss ranged from 0.6 to 19.4% of all sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Guidelines for drug treatment of multiple sclerosis].

Strategies proposed for the treatment of multiple sclerosis are numerous and sometimes contradictory. This review summarizes the most recent studies on the treatment of multiple sclerosis. Possibilities of influencing progression of the disease and the degree of disability suffered by patients are discussed. The treatment of acute relapses with high-dose intravenous glucocorticoids is now widely accepted because it has been shown that the duration of the relapse is reduced. Interval therapy between relapses and treatment of the chronic progressive variant of multiple sclerosis are still under debate. Immunosuppression, in particular with azathioprine, appears to have a positive effect on the long-term outcome. Whether other regimens, e.g., treatment with recombinant lymphokines, have a therapeutic effect, is difficult to assess at present since these substances have either never been tested in controlled double blind studies or the results of these studies are not yet available.

Antineoplastic Agents↗
PubMed1992

Transcription of the chicken anemia virus (CAV) genome and synthesis of its 52-kDa protein.

This paper describes the expression of the chicken anemia virus (CAV) genome, a recently characterized single-stranded circular-DNA virus of a new type [Noteborn et al., J. Virol. 65 (1991) 3131-3139]. The major transcript from the CAV genome is an unspliced mRNA of about 2100 nucleotides (nt). Its transcription start point and poly(A)-addition site are located at nt 354 and 2317 of the CAV sequence, respectively. In vitro translation experiments provide evidence that the major CAV open reading frame encodes a 52-kDa protein by using the fifth AUG as a start codon of the unspliced CAV mRNA.

Blotting, Northern↗
PubMed1992

Posttranslational isoprenylation of rho protein is a prerequisite for its interaction with mastoparan and other amphiphilic agents.

The amphiphilic agents melittin, compound 48/80 and mastoparan inhibit ADP-ribosylation of porcine brain rho protein by Clostridium botulinum exoenzyme C3. However, ADP-ribosylation of recombinant rhoA expressed in E.coli was not inhibited by these agents. Accordingly, steady state GTP hydrolysis by recombinant rhoA was not stimulated by mastoparan, whereas GTP hydrolysis by porcine brain rho was stimulated 2.5-fold in the presence of this wasp venom. After microinjection of recombinant rhoA into Xenopus laevis oocytes the inhibitory effect of mastoparan on C3 ADP-ribosylation was restored. The data suggest that the amphiphilic agents tested are only active at the posttranslationally processed form of rho and that they exert their effects via the C-terminal end.

Adenosine Diphosphate Ribose↗
PubMed1992

Putative invasion-specific proteins in mouse T-cell hybridomas that differ in invasive and metastatic potential.

Fusion of invasive, activated T-lymphocytes with non-invasive BW5147 T-lymphoma cells mainly yields highly invasive (HI), highly metastatic T-cell hybridomas. In addition, several non-invasive (NI), non-metastatic hybrids have been obtained, probably due to loss of involved gene(s) by chromosome segregation. Here we have compared a panel of HI and NI hybrids in a search for proteins specifically expressed by either cell type. MAbs were raised against HI hybrids, but out of more than 1,000 none bound exclusively to HI cells. Furthermore, polyclonal rat, rabbit and chicken antisera did not immunoprecipitate specific proteins from total lysates, and the expression of 18 (T-cell) surface markers did not correlate with invasiveness. These results indicated that the number of differences between HI and NI hybridomas was surprisingly small. This notion was confirmed by 2-dimensional gel electrophoresis. Among 1,000 detectable spots, we found only 2 clear-cut differences between HI and NI T-cell hybridomas, whereas multiple differences were found between individual hybrids. One protein (p130) was expressed at much higher levels by HI than by NI hybrids in this panel, whereas the other (p15) was only seen in NI hybrids. These proteins are primary candidates for a role in invasion.

Animals↗
PubMed1992

ADP-ribosylation of rho proteins is inhibited by melittin, mast cell degranulating peptide and compound 48/80.

The amphiphilic agents melittin, mast cell degranulating peptide and compound 48/80 inhibit the ADP-ribosylation of the small GTP-binding proteins rho by Clostridium botulinum exoenzyme C3. Half-maximal and maximal inhibition (greater than 90%) of ADP-ribosylation occurred at about 8 and 25 micrograms/ml for compound 48/80, at 10 and 45 microM for mast cell degranulating peptide and at 15 and 50 microM for melittin, respectively. In addition, these compounds increase the steady state GTP hydrolysis and the association and dissociation rate of GTP-binding of rho proteins through an increase of GDP/GTP exchange. The data suggest that the amphiphilic agents tested interact with small GTP-binding proteins of the rho protein family.

ADP Ribose Transferases↗
PubMed1992

ADP-ribosylation by Clostridium botulinum C3 exoenzyme increases steady-state GTPase activities of recombinant rhoA and rhoB proteins.

ADP-ribosylation of recombinant rhoA and rhoB proteins by Clostridium botulinum C3 exoenzyme increased steady-state GTP hydrolysis by 50 to 80%. ADP-ribosylation and increase in GTP hydrolysis occurred at similar concentrations of C3, depended on the presence of NAD and were prevented by anti-C3 antibody or heat inactivation of C3. In contrast, GTP hydrolysis by Ile-41 rhoA or Ha-ras, which are no substrates for the transferase, were not affected by C3. ADP-ribosylation facilitated the [3H]GDP release and subsequently, the binding of [3H]GTP to rhoA. The data indicate that the increase in the steady-state GTPase activity by ADP-ribosylation is caused by increasing the rate of GDP release which is suggested to be the rate limiting step of the GTPase cycle of the small GTP-binding proteins.

ADP Ribose Transferases↗
PubMed1992

Clostridium botulinum C3 ADP-ribosyltransferase.

C3 and C3-like ADP-ribosyltransferases modify the low-molecular-mass GTP-binding proteins Rho and Rac. ADP-ribosylation occurs in asparagine-41, which is located in the putative effector region of these highly conserved regulatory proteins. First studies indicate that the Rho proteins are somehow involved in the regulation of cytoskeletal proteins, e.g., microfilament proteins. Although the precise mechanism of the interaction of the C3 substrate with cytoskeletal elements is unclear, it appears that the ADP-ribosylation by C3 renders the GTP-binding protein biologically inactive. Thus C3 and/or C3-like ADP-ribosyltransferases may be useful instruments with which to study the physiological functions of its eukaryotic substrates. Moreover, those studies may help to elucidate whether these exoenzymes are of pathophysiological and pathogenetic relevance in diseases caused by clostridia producing these agents.

ADP Ribose Transferases↗
PubMed1992

Cure profiles of visible-light-cured Class II composite restorations in vivo and in vitro.

The degrees of conversion of posterior composite material in Class II restorations performed in vivo and in vitro were studied by means of the Raman spectroscopy method. Class II restorations in 13 contralateral pairs of premolars were analyzed. The average difference of the ratio I 1610 cm-1/I 1640 cm-1 between the in vivo- and in vitro-performed restorations was 0.42. This indicates a higher grade of conversion in the in vivo situation.

Bicuspid↗