Biomedical subjects

W Schmidt

Publications and source records attributed to W Schmidt.

At least 235 records · Page 13Linked to original sources

PubMed1997

Glycerol and polylysine synergize in their ability to rupture vesicular membranes: a mechanism for increased transferrin-polylysine-mediated gene transfer.

The presence of about 1.2 M glycerol during transfection with DNA/transferrin-polylysine and DNA/polylysine complexes dramatically increases transgene expression in a variety of cell types, provided that the complexes have an excess of polylysine. We have characterized this phenomenon using a human melanoma cell line (H225). The addition of 1.2 M glycerol to the transfection medium has no influence on the internalization of DNA complexes or on the promoter activity used to direct reporter gene expression. Neither prenor postincubation of the cells with glycerol results in a notable increase in transgene expression. Bafilomycin A1 and chloroquine, two drugs affecting the endosomal pathway, both influenced transgene expression, indicating that glycerol acts on internal vesicles. Glycerol and polylysine synergized in their ability to lyse erythrocytes as well as internal vesicles (microsomes) isolated from H225 cells, indicating that the glycerol effect is due to a labilization of vesicular membranes, which facilitates membrane disruption by polylysine. Our current model suggests that the excess of polylysine in the DNA complexes disrupts vesicular membranes in the presence of glycerol, thus allowing the release of DNA complexes into the cytoplasm.

Anti-Bacterial Agents↗

PubMed1997

Transloading of tumor antigen-derived peptides into antigen-presenting cells.

The discovery of a steadily growing number of tumor antigens (TAs) has made generic, cell-free, peptide-based cancer vaccines a possible alternative to cytokine-transfected autologous cellular cancer vaccines. The major drawback of peptide vaccines, however, is the poor immunogenicity of peptides. It is commonly thought that for the induction of an effective anticancer immune response, antigen-presenting cells (APCs) have to display TA-derived peptides to T lymphocytes. Polycationic amino acids have been employed in the past to enhance transport of proteins into cells. In a systematic study, the ability of different cationic polymers to transfer fluorescence-tagged peptides to APCs was investigated. We were able to show that several compounds enhance uptake of fluorescence-labeled peptides by APCs to different degrees. The most efficient compound identified, polyarginine (pArg), enhanced peptide delivery by more than 2 logs as compared with cells treated with peptide alone, whereas polylysine (pLys) treatment resulted in approximately 10-fold increased levels of fluorescence. Augmentation of peptide uptake was concentration-dependent, and the molecular weight of pArg or pLys also influenced peptide delivery. Furthermore, highly negatively charged peptides appear to be delivered with higher efficiency, although neutral peptides were also taken up at enhanced rates. Whereas peptide uptake mediated by pLys appears to be due to an at least transient permeabilization of cell membranes, peptide delivery in the presence of pArg may rely on endocytic processes. TA-derived peptides applied as cancer vaccines in conjunction with polycations afforded antitumor protection in animal models.

Amino Acid Sequence↗

PubMed1997

Cell-free tumor antigen peptide-based cancer vaccines.

The central role that tumor antigen-derived peptides play in induction of antitumor immunity makes them ideal candidates for peptide-based cancer vaccines. We have demonstrated that "transloading" is an efficient strategy for importing short peptide ligands into antigen-presenting cells in vitro. Postulating that the transloading procedure might effect peptide uptake by antigen-presenting cells in vivo as well, we tested this approach for the generation of peptide-based cancer vaccines. In the P815 mastocytoma system, we vaccinated mice by s.c. injection of a single, known natural peptide derived from JAK-1 kinase. Whereas vaccination with peptide alone or mixed with incomplete Freund's adjuvant was ineffective, application of the peptide in conjunction with the polycation poly-L-lysine protected a significant number of animals against tumor challenge. Dependent upon the type of poly-L-lysine applied, protection against tumor take was comparable to that achieved with irradiated whole-cell vaccines, genetically modified to secrete granulocyte-macrophage colony-stimulating factor. In the murine melanoma M-3, a combination of four putative tumor antigen-derived peptides was tested as a cancer vaccine. Administered in combination with polycations, these peptides evoked potent antitumor immunity that could not be obtained with the peptides alone or peptides emulsified in incomplete Freund's adjuvant. However, peptide-polycation vaccines applied to the M-3 model were not as efficient as cellular control vaccines, consisting of irradiated interleukin 2 or granulocyte-macrophage colony-stimulating factor-secreting tumor cells.

Amino Acid Sequence↗

PubMed1997

Analysis of the requirement for beta 2-microglobulin for expression and formation of human CD1 antigens.

Human CD1 form a group of nonpolymorphic leukocyte surface molecules with homology to major histocompatibility complex (MHC) proteins. Recent findings in human and in mouse demonstrate the capacity of CD1 molecules to present nonpeptide components like lipids or lipoglycans as well as peptides. We studied the involvement of beta 2-microglobulin (beta 2m) in expression of the classic human CD1 proteins CD1a, CD1b, and CD1c. The beta 2m-deficient human melanoma cell line FO-1 was transiently transfected with either CD1a, CD1b, or CD1c DNA alone, or in combination with beta 2m using the adenovirus-enhanced receptor-mediated transfer infection system. Only co-transfection of FO-1 cells with CD1+ beta 2m resulted in the detection of CD1 Ag by monoclonal antibodies (mAb). This indicated that CD1 mAb recognized determinants are dependent on beta 2m and raised the question whether beta 2m-free forms of CD1 can be expressed. Therefore, to visualize CD1 molecule expression independently of beta 2m, we expressed tagged recombinant forms. A full-length CD1b construct tagged at the very C terminus with a small peptide was transported to the plasma membrane only when beta 2m was co-transfected. beta 2m involvement in the transport of CD1 was confirmed by expression of soluble forms of CD1a, CD1b, and CD1c in three different cell types. Analogous to tagged full-length CD1b, secretion of the soluble CD1 constructs was strictly dependent on beta 2m. The soluble CD1 chimeras were secreted as complexes with endogenous beta 2m. Thus, similar to its role for MHC class I expression, beta 2m is essential for processing and surface transport of the classic human CD1 molecules CD1a, CD1b, and CD1c.

Antibodies, Monoclonal↗

PubMed1997

Detection of p53 point mutations in primary human vulvar cancer by PCR and temperature gradient gel electrophoresis.

Clinical and experimental evidence is consistent with a key role of point mutations of the p53 tumor suppressor gene in the etiology of squamous cell carcinoma. To determine the relation of tumor behavior and patient survival in vulvar cancer in regard to p53 status, we retrospectively analyzed 38 paraffin-embedded specimens of primary vulvar cancer for genetic alterations of exons 5-8 of the p53 gene. For detection of p53 point mutations we used in vitro amplification by polymerase chain reaction (PCR) and temperature gradient gel electrophoresis (TGGE) and, as a detection method, direct sequencing for mutation verification. p53 point mutations were detected in 12/38 tumor specimens. Patients bearing p53 point mutations showed a significantly shorter relapse-free (log-rank test, P = 0.002) and overall survival time (log-rank test, P = 0.0006). We conclude that PCR-TGGE is an appropriate method for detection of p53 point mutations in paraffin-embedded material. We show that loss of wild-type p53 is an adverse prognostic factor in patients suffering from vulvar cancer.

Adult↗

PubMed1997

Considerations for toxicology studies of respiratory drug products.

The standard approaches for the preclinical development of chronically administered drugs also apply to most respiratory drugs. Modifications from the standard preclinical development plan, however, may be necessary if the drug is administered intranasally or by inhalation. Administration by these routes may result in airway toxicity and the intended patient population is often particularly susceptible. Current and former representatives of the Division of Pulmonary Drug Products (CDER, U.S. FDA) present this article to describe general principles of preclinical development for respiratory drug indications. The article addresses drugs intended for administration by the intranasal or inhalation routes. The article describes the types of studies recommended, considers the initial human dose, and discusses dose-escalation strategies in clinical trials. Other areas of special concern with intranasal or inhalation administration include immunotoxicity, reproductive toxicity, types of dosing apparatus, excipients and extractables, and formulation changes. The approaches described in this article are intended as general information and should be adapted to the scientific considerations and circumstances of a particular drug under development.

Humans↗

PubMed1997

A report on 158 cases of transcervical chorionic villus sampling.

Between 1989 and 1994 first trimester transcervical chorionic villus sampling was offered to 158 patients after proper counselling. The gestational age range was 9-12 weeks. The most important indication was advanced maternal age (75.4%). Adequate sampling after two, and a maximum of three attempts, was achieved in 98% and 99.3% of patients respectively. After the first year of the study karyotyping using the direct method alone was successful in 96% of cases. The success of karyotyping cultures was 98%. Excluding one false positive result the rate of fetal karyotypic abnormalities was 4.8%. 5 spontaneous abortions occurred (3.2%), all in patients of advanced maternal age. Moderate or severe vaginal bleeding occurred in 6.7% of the patients. There was no case of chorioamnionitis.

Abortion, Spontaneous↗

PubMed1997

Sperm count in ejaculates and after sperm selection with discontinuous percoll gradient centrifugation technique, as a prognostic index of IVF outcome.

Success of IVF with low sperm count will depend on the retrieval of the maximum number of normal motile sperms, and this makes the selection of an appropriate technique critical. Various in vitro methods have been developed for selecting human sperm cells. Sperm selection using percoll gradient has been reported to yield upto 60% motile and morphologically normal spermatozoa from a normal semen sample. In this study, we have attempted to determine a possible relationship between sperm count in ejaculates before and after selection with percoll gradient centrifugation on one hand, and fertilization, cleavage and pregnancy rates in an IVF program on the other. With increased sperm count at the time of IVF treatment using selected sperm, we observed higher fertilization, cleavage and gestational rates. In conclusion, sperm concentration before and after selection with percoll may be considered a prognostic parameter for the determination of fertilization potential and pregnancy rates in an IVF program.

Cell Division↗

PubMed1997

Effect of the 21-aminosteroid tirilazad mesylate on leukocyte adhesion and macromolecular leakage during endotoxemia.

BACKGROUND: Interstitial accumulation of leukocytes has been related to the development of multiple organ failure after sepsis. Oxygen radicals are involved in the process of leukocyte adherence to the microvascular wall. This study investigates the effects of the oxygen radical scavenger tirilazad mesylate on leukocyte-endothelial interactions, macromolecular leakage, and microhemodynamics in mesenteric venules during endotoxemia. METHODS: Male Wistar rats were randomly allocated to receive tirilazad mesylate (group A, n = 10), its vehicle (group B, n = 10), or saline 0.9% (group C, n = 10) before a 120-minute infusion of endotoxin (2 mg/kg/hr). Furthermore, a control group without receiving endotoxin (group D, n = 10) was investigated. Leukocyte adherence, emigration of leukocytes, and macromolecular leakage were determined in postcapillary venules of the mesentery by using intravital videomicroscopy. RESULTS: During the administration of endotoxin the number of adherent leukocytes per square millimeter of vessel surface progressively increased in group B (baseline, 431 +/- 35 cells/mm2; 120 minutes, 1121 +/- 71 cells/mm2) and group C (baseline, 398 +/- 44 cells/mm2; 120 minutes, 1290 +/- 116 cells/mm2). In group A no increase in leukocyte adherence was observed after 120 minutes (baseline, 415 +/- 81 cells/mm2; 120 minutes, 638 +/- 87 cells/mm2). In control animals the leukocyte adherence remained unchanged (baseline, 347 +/- 41 cells/mm2; 120 minutes, 507 +/- 75 cells/mm2). After 120 minutes, tirilazad mesylate prevented the increase in leukocyte emigration observed in group B and C. Increased macromolecular leakage during endotoxemia (groups B and C) was not influenced by pretreatment with tirilazad. Tirilazad did not affect the decrease in red cell velocity, volumetric blood flow, and venular shear rate observed during endotoxemia. CONCLUSIONS: This study demonstrates inhibitory effects of tirilazad on endotoxin-induced leukocyte adherence and emigration, suggesting a potential therapeutic role for this substance in the prevention of sepsis-induced multiple organ failure.

Animals↗

PubMed1997

After-effects of a high altitude expedition on blood.

The aim of the study was to investigate blood alterations caused by altitude acclimatization which last more than few days after return and might play a role for exercise performance at sea level. Measurements were performed in 12 mountaineers before, during and either 7/8 or 11/12 days after a Himalaya expedition (26-29 days at 4900 to 7600 m altitude). [Erythropoietin] rose only temporarily at altitude (max. +11 +/- 1 [SE] mu/ml serum). After return hemoglobin mass (initially 881 +/- 44 g, CO-Hb method) was increased by 14% (p < 0.01); aspartate aminotransferase activity in erythrocytes (initially 682 +/- 25 U/l) was augmented (day 7: +964 +/- 152 U/l, day 11: +533 +/- 107 U/l) indicating reduced mean cell age. Calculated blood volume (+14%) was influenced by red cell formation at altitude but also by plasma expansion at sea level. The half saturation pressure for Hb-O2 (pH 7.4, 37 degrees C) as well as the 2.3-diphosphoglycerate concentration were already initially high (32.1 +/- 0.5 mmHg, 20.5 +/- 0.7 mumol/g Hb) and showed only a nonsignificant tendency to increase after return. Also Hill's n was consistently high in the mountaineers, whereas the Bohr coefficients were slightly increased only after descent. Probably the preparatory physical training, partly in the Alps, and the stay in the Himalaya influenced O2-affinity for a prolonged time. The adaptations might reduce the loss of physical performance capacity at altitude and be part of altitude training effects.

Acid-Base Equilibrium↗

PubMed1997

Antenatally detectable markers for the diagnosis of autosomally trisomic fetuses in at-risk pregnancies.

Our aim was to investigate the contribution of certain antenatally detectable markers leading to the diagnosis of trisomic fetuses we observed over a period of 6 years. In our study, we specifically analyzed the role played by advanced maternal age and sonographically discovered abnormalities in the detection of autosomal trisomies. All together, 27 fetuses had this disorder, representing 28.7% (27 of 94) of all cytogenetic aberrations detected at our center over the same period. Down syndrome (12 cases) and Edward syndrome (11 cases) were the most common trisomies, while 4 cases of Patau syndrome were also diagnosed. The most common indication leading to diagnosis was abnormal ultrasound finding (48.2%), followed by advanced maternal age (44.4%). However, 63% of the trisomic fetuses belonged to mothers aged 35 years and above. Down syndrome fetuses (41.7%) had prenatally detected sonographic anomalies, 63.6% for Edward syndrome, and all fetuses with Patau syndrome (4 of 4) showed abnormal sonographic signs. Trisomy 21 presented with the following features: hydramnios, complex malformations, pyelectasis, and duodenal atresia. Trisomy 18 fetuses showed hydramnios, intrauterine growth retardation, microcephaly, spina bifida, and nonimmune hydrops fetalis. Signs observed in fetuses with trisomy 13 were: hydrocephalus, intrauterine growth retardation, oligoanhydramnios, complex malformations, severe fetal bradycardia and hydronephrosis.

Adult↗

PubMed1997

[Receptor mediated gene transfer in squamous epithelial carcinoma of the head-neck area].

BACKGROUND: The "Adeno-Virus-Enhanced-Receptor-Mediated" (AVET)-System uses the receptor-mediated endocytosis route to introduce DNA into mammalian cells. By the help of a replication defective adenovirus with endosomolytic activity the coentry of receptor-bound DNA particles is faciliated. The transport to the nucleus followed by gene expression is multifold enhanced. METHODS: Two different permanent cell lines from head and neck squamous cell cancer were transfected with the reportergene for luciferase with either AVET or different liposoms in vitro. RESULTS: In comparison it becomes obvious, that AVET shows a multifold higher transfection rate in vitro than the liposomal formulations applied. CONCLUSIONS: AVET could be used for efficient transfection of epithelial cells, that are fairly reluctant to DNA transfer. Further trials in the mouse model must prove a possible application in vivo.

Adenoviruses, Human↗

PubMed1997

Influence of lidocaine on endotoxin-induced leukocyte-endothelial cell adhesion and macromolecular leakage in vivo.

BACKGROUND: Endotoxin activates leukocyte-endothelial cell adhesion, vascular leakage, and changes in vascular micro-hemodynamics. The aim of this study was to determine whether lidocaine, which inhibits the activation of leukocytes, could attenuate microcirculatory disturbances during endotoxemia. METHODS: Thirty anesthetized male rats were randomly assigned to receive one of three treatments (n = 10 for each group): infusion of saline (control group), infusion of Escherichia coli endotoxin (LPS group: 2 mg x kg(-1) x h(-1) lipopolysaccharides) without lidocaine treatment, or infusion of endotoxin with lidocaine pretreatment 30 min before baseline measurements (lidocaine group: intravenous bolus of 2 mg/kg and continuous infusion of 2 mg x kg(-1) x h(-1)). Leukocyte adherence, erythrocyte velocity (V(RBC), and vessel diameters (Dv) were determined at baseline and at 60 and 120 min in mesenteric postcapillary venules using in vivo videomicroscopy. Macromolecular leakage was determined by measuring the extravasation of fluorescence-labeled albumin. Venular wall shear rate (tau) was calculated according to the equation tau = 8 x V(RBC) x Dv(-1). RESULTS: Lidocaine significantly attenuated the increase of leukocyte adherence during endotoxemia. There were no significant differences of tau within or between the groups. Macromolecular leakage exhibited the greatest increase in the LPS group. In the lidocaine group, it was significantly decreased but still increased compared with the control group. CONCLUSIONS: These results show that lidocaine attenuates endotoxin-induced alterations in leukocyte-endothelial cell adhesion and macromolecular leakage, which suggests that lidocaine may have a therapeutic role in preventing endothelial damage in sepsis.

Anesthetics, Local↗

PubMed1997

Mucosal abnormalities in microsporidiosis.

OBJECTIVE: To determine the prevalence of microsporidiosis in HIV-infected patients with and without diarrhoea and to characterize alterations in mucosal architecture and brush border enzyme activities in patients with microsporidiosis. PATIENTS: A total of 259 HIV-infected patients undergoing oesophago-gastroduodenoscopy because of diarrhoea (n = 123) or other symptoms (n = 136) were studied. METHODS: Patients were evaluated for the presence of microsporidia by electron microscopy of duodenal biopsies. Brush border enzyme activities were measured by histochemistry and mucosal architecture was determined by three-dimensional morphometry in biopsies from patients with microsporidiosis and compared with biopsies from a subgroup of HIV-infected patients with or without other enteropathogens. RESULTS: Enterocytozoon bieneusi was detected in 17 patients and Encephalitozoon intestinalis was detected in two patients. Microsporidiosis was significantly more frequent in patients with chronic diarrhoea (19.1%; P < 0.0001) or in patients with acute diarrhoea (7.2%; P = 0.04) than in patients without diarrhoea (1.5%). Microsporidiosis was associated with lactase deficiency (P = 0.03) and a reduced activity of alkaline phosphatase (P = 0.028) and alpha-glucosidase (P = 0.025) at the basal part of the villus compared with brush border enzymes in patients without enteropathogens. Patients with microsporidia had reduced villus height (P = 0.043) and a villus surface reduced by 40% (P = 0.004) compared with patients with enteropathogens other than microsporidia. CONCLUSIONS: Our study confirms the association between microsporidia and diarrhoea. The pathophysiologic mechanism by which microsporidia cause diarrhoea appears in part to be malabsorption, caused by a reduction of absorptive mucosal surface and impairment of enterocyte function.

AIDS-Related Opportunistic Infections↗

PubMed1997

N-acetylcysteine attenuates endotoxin-induced leukocyte-endothelial cell adhesion and macromolecular leakage in vivo.

OBJECTIVE: To determine the influence of N-acetylcysteine on endotoxin-induced leukocyte-endothelial cell adhesion, vascular leakage, and venular microhemodynamics. DESIGN: Randomized, blinded, controlled trial. SETTING: Experimental laboratory. SUBJECTS: Thirty male Wistar rats. INTERVENTIONS: After pretreatment with N-acetylcysteine (150 mg/kg; n = 40; group A) or 0.9% saline solution (n = 10; group B) animals were given an intravenous infusion of endotoxin (Escherichia coli lipopolysaccharide 026:B6; 2 mg/kg/hr) over 120 mins. Animals in the control group (n = 10; group C) received a volume-equivalent infusion of 0.9% saline solution. MEASUREMENTS AND MAIN RESULTS: Leukocyte adherence, red cell velocity (VRBC), vessel diameters, venular wall shear rate, and macromolecular leakage were determined in mesenteric postcapillary venules using in vivo videomicroscopy at baseline and at 30, 50, 90, and 120 mins after the start of the endotoxin challenge. Endotoxin exposure induced a marked increase in adherent leukocytes (group B: baseline, 391 +/- 24 cells/mm2; 120 mins, 1268 +/- 131 cells/mm2; p < .01). N-acetylcysteine pretreatment attenuated the adherence of leukocytes during endotoxemia (baseline, 366 +/- 28 cells/mm2; 120 mins, 636 +/- 49 cells/mm2; p < .01 vs. baseline; p < .01 vs. group B). Leukocyte adherence in control animals (group C) did not increase significantly. Administration of N-acetylcysteine did not influence the decrease in VRBC observed during endotoxemia. In group B1 VRBC decreased during the infusion of endotoxin from 2.0 +/- 0.2 mm/sec at baseline to 1.1 +/- 0.2 mm/ sec after 120 mins (p < .01 vs. baseline; p < .05 vs. group C), and in group A from 2.2 +/- 0.2 mm/sec to 1.1 +/- 0.1 mm/sec after 120 mins (p < .01 vs. baseline; p < .05 vs. group C). In group C, VRBC remained unchanged (baseline, 1.7 +/- 0.2 mm/sec; at 120 mins, 1.5 +/- 0.2 mm/sec). The venular diameters remained unchanged in all groups during the entire study period. After 120 mins, the venular wall shear rate decreased from 502 +/- 62 secs-1 at baseline to 272 +/- 46 sec-1 in group B (p < .01), and from 563 +/- 45 secs-1 at baseline to 283 +/- 31 secs-1 in group A (p < .01). No differences in venular wall shear rate were observed between these groups. In group C, the venular wall shear rate remained unchanged (baseline, 457 +/- 54 secs-1; at 120 mins, 409 +/- 51 secs-1). Macromolecular leakage, expressed as perivenular/intravenular fluorescence intensity after injection of fluorescence-labeled albumin, increased from 0.29 +/- 0.03 to 0.58 +/- 0.03 (p < .01) during the infusion of endotoxin in group B. In contrast, pretreatment with N-acetylcysteine diminished the extravasation of albumin (baseline, 0.27 +/- 0.01; at 120 mins, 0.37 +/- 0.02; p < .01 vs. baseline; p < .01 vs. group B). CONCLUSION: These results demonstrate that N-acetylcysteine attenuates endotoxin-induced alterations in leukocyte-endothelial cell adhesion and macromolecular leakage, suggesting N-acetylcysteine might be therapeutic in the prevention of endothelial damage in sepsis.

Acetylcysteine↗

PubMed1997

Life-threatening dysrhythmias in severe thioridazine poisoning treated with physostigmine and transient atrial pacing.

OBJECTIVES: To describe clinical, electrocardiographic, and blood chemistry findings in a case of high-dosage thioridazine self-poisoning, focusing on the cellular mechanisms of the cardiovascular toxicity. DESIGN: Case report and literature review. SETTING: Intensive care unit (ICU) of a district hospital in Germany. PATIENT: A 68-yr-old male patient admitted to the ICU for treatment of a severe thioridazine intoxication. INTERVENTIONS: Prevention of absorption (gastric lavage), mechanical ventilation, fluids, alkalinization, catecholamines, drugs (physostigmine, neostigmine), direct current cardioversion/defibrillation, and transient pacemaker (atrial stimulation). MEASUREMENTS AND MAIN RESULTS: Central nervous, cardiovascular, and gastrointestinal systems indicated the adverse side effects of thioridazine intoxication over a period of 9 days. During high toxic thioridazine plasma concentrations (6061 to 6480 ng/mL), a life-threatening crisis occurred due to malignant ventricular arrhythmias followed by bradycardia (e.g., sinus node arrest). The electrocardiogram showed delays in all parts of the conduction system of the heart, including prolonged repolarization for several days, which disappeared completely when thioridazine plasma concentrations were within the therapeutic range. CONCLUSIONS: An individual therapeutic approach is needed in cases of thioridazine overdose. The primary aim is to stabilize the cardiac rhythm and the circulation.

Aged↗

PubMed1997

Modelling of non-linear pharmacokinetics in sheep after short-term infusion of cardiotoxic doses of imipramine.

Imipramine was administered to sheep (n = 10) by intravenous infusion in high doses (450 mg-900 mg) to elicit cardiovascular shock. A cardiac assist device was then employed to manage the acute overdose situation. The concentration-time course of imipramine and its metabolite desmethylimipramine in plasma was measured by HPLC. As an indicator of imipramine's cardiotoxic effect, cardiac output was monitored. The aim of the study was to evaluate the pharmacokinetics under these conditions and to assess the efficiency of a cardiac assist device with (n = 5) and without (n = 5) an integrated haemoperfusion unit in removing drug from the circulation. The kinetics of imipramine could be described by a three compartment body model with concentration-dependent clearance resulting in non-linear kinetics. The changes in cardiac output with time could be linked to the pharmacokinetic model by a linear relationship. The cardiac assist device was found to contribute to the overall elimination of imipramine whereas the haemoperfusion unit had no clinically relevant impact.

Animals↗

PubMed1997

Comparative evaluation of modified trichrome and Uvitex 2B stains for detection of low numbers of microsporidial spores in stool specimens.

At present, the laboratory diagnosis of intestinal infections caused by microsporidia depends on the detection of the typical spores either with a modified trichrome stain (MTS) or by staining with fluorochromes. The purpose of the present study was (i) to compare staining with MTS (MTS method) and the staining with the fluorochrome Uvitex 2B (U2B method) with respect to their sensitivities and specificities, particularly in the presence of low numbers of spores, and (ii) to evaluate their reliabilities under routine laboratory conditions. First, 30 negative human stool specimens as well as 30 specimens enriched with a low concentration of microsporidial spores were examined. The U2B and MTS methods detected 27 and 30, of the positive samples, respectively (95% confidence intervals for sensitivity, 0.73 to 0.98 for the U2B method and 0.88 to 1.00 for the MTS method) without yielding false-positive results (95% confidence intervals for specificity, 0.88 to 1.00 for the MTS and U2B methods). In addition, analysis of serial dilutions of 17 stool specimens from AIDS patients containing microsporidia revealed comparable detection thresholds (P = 0.52) for both methods. Finally, 40 slides prepared from one stool specimen containing very few microsporidia and 40 negative slides were included in the routine diagnostic program during 1 month in order to monitor laboratory handling and run-to-run variations. Again, both methods exhibited comparable sensitivities (95% confidence intervals, 0.83 to 0.99 for the MTS method and 0.91 to 1.00 for the U2B method) and specificities (95% confidence intervals, 0.91 to 1.00 for the MTS and U2B methods). In conclusion, MTS and U2B methods are equally useful in the diagnosis of microsporidiosis. However, since detection thresholds for both methods differed considerably in all diluted stool specimens, performance of a combination of both methods may be more sensitive than the performance of only one procedure in the event of very low numbers of microsporidial spores.

AIDS-Related Opportunistic Infections↗