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Biomedical subjects

R Klett

Publications and source records attributed to R Klett.

35 records · Page 2Linked to original sources
PubMed1983

Drug interactions I: detection of inorganic nitrite in organic nitrate esters under acidic conditions simulating the human stomach.

Both unformulated (bulk) and formulated (drugs) organic nitrate esters (isosorbide dinitrate, nitroglycerin, and pentaerythritol tetranitrate) were studied in the presence and absence of hydrochloric acid to determine if they could be sources of nitrite (and therefore lead to nitrosamine formation) under acidic conditions similar to those found in the stomach. The presence and generation of nitrite ion was detected by a modification of the Griess reaction. Bulk isosorbide dinitrate and nitroglycerin were found to be contaminated with 13.8-121.4 mumoles of inorganic nitrite per mole of nitrate ester. In addition, in the presence of hydrochloric acid, these preparations generated 0.52-1.18 mumoles of inorganic nitrite/mole of nitrate ester/min. Unformulated nitroglycerin generated nitrite at a rate roughly twice that of isosorbide dinitrate. In contrast, no evidence for nitrite contamination or generation by pentaerythritol tetranitrate was found. Tablets and capsules of isosorbide dinitrate contained approximately 27-216 mumoles of nitrite/mole of nitrate ester and, in the presence of hydrochloric acid, generated an average of 0.55 mumole nitrite/min. For isosorbide dinitrate, this rate was similar for bulk and formulated drug. In comparison to isosorbide dinitrate, the amount of nitrite initially present in tablets and capsules of nitroglycerin varied more widely (approximately 25-2290 mumoles nitrite/mole of nitrate ester), and in this case nitrite was generated at higher rates than unformulated drug averaging approximately 4.7 mumoles nitrite/mole of nitrate ester/min. Contrary to a literature report, we found that nitrate ion is not reduced to nitrite by hydrochloric acid (pH 1-3).(ABSTRACT TRUNCATED AT 250 WORDS)

Chemistry, Pharmaceutical↗
PubMed1979

[Correction of the inclination of the condylar guidance by changing the Bennett angle on the Dentatus articulator].

Since there is an interrelationship between construction-related inclination of condylar guidance and the Bennett angle with the Dentatus articulator, Lauritzen suggested that the inclination of condylar guidance be adjusted 1 degree in the opposing direction for every 5 degrees alteration in the Bennett angle. This method was rejected because calculations of the interdependence of condylar guidance and Bennett angle showed the results, in some cases, to be worse than when the angle was not adjusted. An exact correction procedure was described.

Dental Articulators↗
PubMedDate not supplied

[Staged diagnosis of septic hip endoprosthesis loosening with laboratory parameters and antigranulocyte scintigraphy].

AIM: The value of serial diagnosis of septic loosening of hip endoprosthesis using laboratory parameters and antigranulocytes scintigraphy was investigated and compared to joint aspiration. METHOD: In 35 patients with intraoperative verification of infection, we calculated sensitivity, specify and prevalence dependent positive and negative predictive values for antigranulocyte scintigraphy, laboratory tests and the most suitable combination of both. We also calculated predictive values of joint aspiration using sensitivity and specify values given in the literature. RESULTS: From negative and positive predictive values, of the sedimetation rate and leukocyte count provided no increase of information. We found the same result for positive predictive values of C-reactive protein. For antigranulocyte scintigraphy alone, we found a distinct but still unsatisfying increase of information. Nevertheless, in both cases infection could be excluded definitely. Therefore, the combination of C-reactive protein and antigranulocyte scintigraphy was suitable and the positive predictive values of this combination were only about 5% lower than those of joint aspiration. But with joint aspiration, infection could not be excluded. CONCLUSION: A positive result in serial diagnosis using C-reactive protein and antigranulocyte scintigraphy leads to an distinct increase in the probability of infection which is comparable to that of joint aspiration. The additional advantages of this procedure are the certain exclusion of infection and the absence of invasiveness.

Aged↗
PubMedDate not supplied

[Stage diagnostics for postinfection revision of hip and knee replacement: value of laboratory parameters and antigranulocyte scintigraphy].

AIM: In the case of two-stage infect revision arthroplasties of hip and knee joint, of primary resection arthroplasties and before implantation of arthroplasties after septic arthritis the accuracy of preoperative laboratory parameters and antigranulocyte scintigraphy was analysed. Furthermore, we stained the intraoperatively taken joint synovial samples with hematoxylin-eosin and also with antibodies against human neutrophil elastase in order to investigate if immunohistological examination provides further or different information. METHOD: In 24 patients with intraoperative verification of infection we calculated sensitivity, specificity, positive and negative predictive values for laboratory tests, antigranulocyte scintigraphy and the most suitable combination of both. The joint synovial samples stained with antibodies against human neutrophil elastase were compared to those stained with hematoxylin-eosin according to the criteria of Mirra. RESULTS: We observed the best results for the combination of C-reactive protein and antigranulocyte scintigraphy with a sensitivity of 1, a specificity of 0.92, a positive predictive value of 0.75 and a negative predictive value of 1. No additional or different information was observed by the immunohistological stained samples. CONCLUSION: Stage diagnostic using C-reactive protein and antigranulocyte scintigraphy provides accurate information to assess the status of infection before hip and knee replacement after infect revision. Additional immunohistological staining besides the routinely taken hematoxylin-eosin staining of joint synovial samples is not recommended.

Aged↗
PubMedDate not supplied

[Infection diagnosis after knee-TEP-implantation].

AIM: In this study, the accuracy of antigranulocyte scintigraphy as a diagnostic means prior to revision in infected total knee replacement was compared to that of preoperative joint aspiration and laboratory parameters. The most efficient combination of all diagnostic methods was calculated and thus a diagnostic algorithm recommended. The value of PCR was compared to commonly used techniques of microbiological culturing. METHODS: Preoperative diagnostic means for infection of 50 total knee replacements in 45 patients requiring revision surgery, were retrospectively analyzed. Inclusion criteria were the intraoperative microbiological and histological verification of infection. Sensitivity, specificity, negative and positive prediction value of C-reactive protein (CRP) and leukocytes, antigranulocyte scintigraphy with (99m)Tc-labeled antibodies, and preoperative joint aspiration were calculated. Furthermore, the accuracy of the different techniques of culturing was compared to that of the polymerase chain reaction (PCR) based on the intraoperative histological findings. Two blinded examiners evaluated specimens taken intraoperatively according to the criteria of Mirra. RESULTS: We observed a sensitivity of 1.0, a specificity of 0.82, a positive prediction value of 0.83 and a negative prediction value of 1.0 for the antigranulocyte scintigraphy. The sensitivity of preoperative joint aspiration was 0.5, the specificity 1.0, and the positive and negative prediction values were 1.0 and 0.5. Correlated to the intraoperative histological findings the accuracy of PCR and culturing was comparable. The highest accuracy was obtained for blood culture samples. CONCLUSION: Compared to preoperative joint aspiration the antigranulocyte scintigraphy proved to be more sensitive in the diagnosis an infected knee replacement while having a high specificity. An advantage of PCR compared to the common microbiological culturing techniques was not observed.

Aged↗