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Biomedical subjects

J Knobloch

Publications and source records attributed to J Knobloch.

At least 37 records · Page 2Linked to original sources
PubMed1997

Loss of in vitro cytotoxicity of cisplatin after storage as stock solution in cell culture medium at various temperatures.

BACKGROUND: Cisplatin (cis-dichlorodiammineplatinum [II]) is one of the most potent and widely used cytotoxic drugs in cancer therapy. However, in vitro cytotoxicity assays often yield diverging results. Therefore, it is believed by many investigators that cisplatin is not effective in vitro. The authors investigated whether the experimental conditions used could be responsible for the diverging results. METHODS: In vitro cytotoxicity assays were performed using the original cisplatin solution as distributed by the manufacturer or a 5-fold dilution of this in cell culture medium after storage for 2 weeks or 1 month at various temperatures (room temperature, 4 degrees C, and -20 degrees C). RESULTS: The original solution of cisplatin retained the full cytotoxic potency for at least 1 month under all storage conditions tested. The highest loss of cytotoxicity resulted from storage of cisplatin in cell culture medium in which a >7-fold increase in the concentration that inhibits 50% occurred after 2 weeks' storage at room temperature. Solutions stored in culture medium at -20 degrees C retained full cytotoxic potency. CONCLUSIONS: Cisplatin is a potent cytotoxic drug in vitro when stored under appropriate conditions. These findings are of relevance for in vitro studies with cisplatin.

Antineoplastic Agents↗
PubMed1997

A new method for isolation and differentiation of native Entamoeba histolytica and E. dispar cysts from fecal samples.

A new method for the purification of protozoan cysts from feces was established, allowing to isolation of native cysts. The procedure consists of two sucrose-density gradients and enzymatic digestion of cellulose particles by cellulase and can be accomplished in a few hours. The cyst fractions were differentiated into Entamoeba histolytica and E. dispar using the DNA probes P145 and B133 and a dot-blot test.

Animals↗
PubMed1997

Sensitivity of Entamoeba histolytica and Entamoeba dispar patient isolates to human complement.

Twenty-one Entamoeba histolytica and 56 Entamoeba dispar patient isolates were investigated for their sensitivity to the classical and alternative pathway of human complement, E. histolytica and E. dispar patient isolates were differentiated by polymerase chain reaction and hexokinase isoenzyme typing. It was found that 90.3% (+/- 12.0%) of the trophozoites of E. histolytica were lysed after 30 min by the alternative pathway of complement in the presence of 50% human serum (19 isolates showed lysis rates higher than 80%), whereas E. dispar cells were less susceptible to the alternative pathway as 68.8% (+/- 28.2%) of lysis occurred. However, 23 of the E. dispar isolates were lysed between 100 and 80% (90.9% +/- 9.1%), demonstrating that about half of the tested E. dispar isolates were highly sensitive to complement lysis. Only 11 of the E. dispar isolates were proven to be ¿resistant' to the alternative pathway of complement and were lysed less than 40%. These results are in conflict to earlier publications, describing resistance of E. dispar to complement lysis (Hamelmann et al. 1992, 1993).

Animals↗
PubMed1997

Accidental Leishmania mexicana infection in an immunosuppressed laboratory technician.

A 30 year-old female laboratory technician under immunosuppressive treatment because of systemic lupus erythematosus (SLE) developed cutaneous leishmaniasis 8 months after accidental percutaneous inoculation of amastigote culture forms of Leishmania mexicana. Leishmania-specific PCR and restriction analysis patterns were identical for both the laboratory strain and the clinical specimen. The lesion was resistant to local paromomycin and oral ketoconazole, but responded to local application of meglumine antimonate. No signs of dissemination or visceralization occurred during the 5-month period of observation. However, a future recurrence cannot be excluded since a persistent infection even after clinical cure has always to be considered in leishmaniasis. Patients under immunosuppressive therapy are possibly at risk of clinical relapse or disseminating infection although there is no experience with regard to leishmaniasis mexicana. Serious infection may require interferon gamma as part of the treatment which may contribute to deterioration of concomitant diseases like SLE. In any case, the exposure of immunodeficient laboratory workers to Leishmania spp. should be avoided.

Adult↗
PubMed1997

Isoenzyme patterns of Blastocystis hominis patient isolates derived from symptomatic and healthy carriers.

Isolates of Blastocystis hominis derived from patients with intestinal symptoms and from healthy carriers were cultured in vitro and isoenzyme patterns of hexokinase (E.C. 2.7.1.1), phosphoglucomutase (E.C. 2.7.5.1) and glucose phosphate isomerase (E.C. 5.3.1.9) were investigated to find evidence for pathogenic and non-pathogenic subspecies of B. hominis. For this purpose we examined 2000 patients of the out-patient department of the Institute for Tropical Medicine in Tübingen. From these, we obtained 232 B. hominis patient isolates; 119 isolates could be tested for the three isoenzymes. Blastocystis hominis possesses 5 patterns for hexokinase, 11 for phosphoglucomutase and 35 for glucose phosphate isomerase, showing that B. hominis is highly polymorphic. However, there was no correlation between isoenzyme patterns and disease of patients.

Animals↗
PubMed1997

Exchange blood transfusion in severe falciparum malaria: retrospective evaluation of 61 patients treated with, compared to 63 patients treated without, exchange transfusion.

The rationale for exchange blood transfusion (ET) in severe falciparum malaria is threefold: reduction of parasitaemia, reduction of presumptive 'toxic' factors, and improvement of the rheological quality of the blood. We evaluated the records of 61 patients treated with ET to describe the present status of malaria treatment in Germany, Austria and Switzerland and to assess the efficacy of ET. Clinical data of 61 patients treated with ET were compared to data of 63 patients treated in 2 hospitals where ETs were generally not performed. We found that exchange transfusion is applied according to the clinician's subjective impression rather than strict guidelines. Logistic regression analysis adjusting for the differences in clinical parameters between patients treated with or without ET did not identify treatment as a prognostic indicator (odds ratio for relative risk of death with ET: 1.3; 95% CI: 0.4-4.9). Exchange transfusion did not significantly improve the unfavourable prognosis in cases of severe falciparum malaria. However, failure to reach statistical significance may be due to the retrospective design of the study and therefore non-systematic approach.

Adult↗
PubMed1997

Five subgroups of Blastocystis hominis from symptomatic and asymptomatic patients revealed by restriction site analysis of PCR-amplified 16S-like rDNA.

DNA polymorphism of Blastocystis hominis isolates was examined by the amplification of a gene fragment coding for the 16S-like rDNA. Using identical primers, fragments of approximately 850 bp were amplified from 110 B. hominis isolates and fragments of 1.1 kbp were amplified from 48 isolates. Digestion of the amplification products with the restriction enzymes HinfI, RsaI, and AluI revealed different profiles for each fragment length. Subgroup I and II, resulting from digestion of the smaller 850 bp fragment, have identical HinfI and AluI restriction bands, subgroup III and IV have identical RsaI fragments after digestion of the 1.1 kbp DNA. Subgroup V resembles subgroup III in a few bands after the RsaI and AluI restriction, respectively. Ninety (54%) of the isolates studied were assigned to subgroup I, 20 (12%) to subgroup II, 35 (21%) to subgroup III, 12 (7%) to subgroup IV, and 1 (1%) to subgroup V. Five (3%) of the examined people were coinfected with B. hominis of the subgroup III, 3 (2%) carried B. hominis of the subgroup I and II. These results show that there are 5 B. hominis subgroups none of which was found to be significantly correlated with the reported disease.

Animals↗
PubMed1997

Impaired production of cytokines in a case of human leishmaniasis.

A patient presented with the unique clinical picture of diffuse cutaneous and mucosal leishmaniasis caused by Leishmania tropica. Elevated serum levels of several cytokines including interleukin (IL) 2, interferon gamma (IFN-gamma), and tumor necrosis factor alpha were found. All cytokine levels returned to normal during therapy. No IL-10 or IL-4 levels were detectable. In whole blood cultures, induction of IFN-gamma by lipopolysaccharide (LPS) was completely negative, even after therapy. Concanavalin A (Con A)-induced release of IFN-gamma, like Con A-induced release of the other cytokines, was only initially impaired but returned to normal during therapy. Induction of the other cytokines by LPS was never impaired. The low expression of human leukocyte antigen DR on monocytes increased during IFN-gamma therapy but dropped when IFN-gamma treatment was ceased. We conclude that in this patient one or more of the routes of IFN-gamma production was impaired, thus resulting in insufficient IFN-gamma production in the infected lesions (although IFN-gamma was systemically present).

Adolescent↗
PubMed1997

Bartonellosis in Ecuador: serosurvey and current status of cutaneous verrucous disease.

Human bartonellosis is a classically biphasic disease caused by infection with the alpha-2 Proteobacteria Bartonella bacilliformis, which is phylogenetically related to the etiologic agents of cat scratch disease, bacillary angiomatosis, and trench fever. In Ecuador, typical bartonellosis has remained endemic for the past century in highland provinces near the Peruvian border. During the past six years, public health officials have noted an increasing number of atypical cases in which monophasic verrucous cutaneous disease is the only clinical manifestation. Epidemiologic, immunologic, histopathologic, and molecular biological studies have confirmed the presence of sporadic, atypical bartonellosis in residents of the lowland province of Manabi, where archeologic evidence exists of bartonellosis in pre-Colombian times. Between 1987 and 1995, 11 cases of cutaneous bartonellosis were investigated and serologic studies were done on 224 persons from five villages, two lowland and three highland. In the lowland village of Pajan in the province of Manabi, there was a 21% seropositivity proportion in contacts of index cases. These combined data suggest that bartonellosis is significantly under-reported due to the existence of mild clinical disease, possibly associated with less virulent bacterial strains, which are now disseminating or re-emerging in previously disease-free areas.

Antibodies, Bacterial↗
PubMed1997

Differentiation of Entamoeba histolytica and Entamoeba dispar from German travelers and residents of endemic areas.

Entamoeba histolytica and E. dispar detected in fecal samples of German travelers and residents of tropical and subtropical countries were cultured and differentiated by the polymerase chain reaction (PCR) and hexokinase isoenzyme typing. Twenty-one of 60 isolates were identified as E. histolytica. It was shown that 13 of 18 German short-term travelers were infected with E. histolytica, whereas only three of 22 of the examined inhabitants of tropical countries and five of 20 German long-term travelers harbored E. histolytica. It appears that short-term travelers represent a high risk group for infection with the pathogen E. histolytica.

Animals↗
PubMed1996

Parasite-specific lactate dehydrogenase for the diagnosis of Plasmodium falciparum infection in an endemic area in west Uganda.

The measurement of parasite lactate dehydrogenase (pLDH) has been presented as an easy and rapid method for the diagnosis of malaria in humans. In order to evaluate the sensitivity and specificity of such a test we examined blood samples from 429 Ugandan patients. While pLDH activity was significantly linked to parasitaemia, sensitivity and specificity were found to be rather low at 58.8 and 62.2% respectively. The positive and negative predictive values failed to meet necessary standards. We conclude that the methods of measurement of pLDH activity in malaria infection, although potentially useful for the fast diagnosis of malaria, need to be improved to be of true value in endemic areas.

Humans↗
PubMed1995

Increased erythropoietin production in children with severe malarial anemia.

Plasma immunoreactive erythropoietin concentrations were determined in 84 children with Plasmodium falciparum malaria in Gabon. There was an inverse log/linear relationship between hemoglobin or hematocrit and plasma erythropoietin, indicating that erythropoietin levels increased exponentially as circulating hemoglobin decreased. These result show that P. falciparum malaria does not lead to decreased erythropoietin production, and in turn reduced erythropoietin production does not contribute to the pathogenesis of malarial anemia. There is an adequate response of erythropoietin to anemia in children with P. falciparum malaria.

Age Factors↗
PubMed1994

[Microbiological diagnosis of malaria and amoebiasis].

All stages of malaria and amebiasis may be sensitively and specifically diagnosed by means of microbiological methods. Microscopical parasitology holds a key position when supplemented by immunodiagnostic assays. Molecular biology techniques are currently still inferior to the above procedure. Tests for the differentiation between pathogenic and nonpathogenic Entamoeba histolytica (Entamoeba dispar) require further simplification before generally applicable.

Amebiasis↗