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Biomedical subjects

R Engelhardt

Publications and source records attributed to R Engelhardt.

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

[Optical coherence tomography of the cornea and the anterior eye segment].

TARGET: The method of optical coherence tomography (OCT) was investigated regarding its suitability and limits for measuring the cornea and the anterior segment of the eye. Furthermore, the stromal expansion of thermally induced lesions in the cornea directly after irradiation was determined within the scope of the laser thermokeratoplasty (LTK). MATERIAL AND METHODS: With the experimental scanning OCT system, x-z sections of the anterior eye segment were made with an optical resolution of about 20 microns axially and 25 microns laterally. Freshly enucleated, tonicized porcine eyes were used as model eyes. Thermal lesions were applied with a continuously emitting laser diode (lambda = 1.86 microns) and various radiation parameters. Before and after coagulation, the cornea was viewed from limbus to limbus in a central OCT scan and the individual coagulation source was measured. RESULTS: Global and local changes of the thickness of the cornea as well as the distance between cornea and lens were measured with high precision. Thermal lesions in their expansion can be dearly presented and matching well with the histologically stained sections, but are not as exactly defined at the edges due to the limited optical resolution, as known from histological preparations. CONCLUSION: With the OCT method quantitative measuring of the anterior eye segment can be performed in vitro and with reduced resolutions also in vivo. Due to the qualitatively good correspondence regarding the dimensions of thermal damage of the cornea with histologically obtained morphometric results, this method can be used for supervision of coagulation directly after LTK as well as for examination of the individual healing process.

Animals↗
PubMed1997

[Imaging of laser thermokeratoplasty lesions by optical low coherence tomography and polarization microscopy after Sirius Red staining].

BACKGROUND: Information on the extent and degree of the thermal effect produced is of great importance for control of the laser dosage in laser thermokeratoplasty (LTK) and for postoperative follow-up. We investigated on acute LTK effects which information images obtained by optical low coherence tomography (OCT) offer compared to those obtained by polarization microscopy. METHODS: Porcine eyes were irradiated through a 400 microns quartz fiber using light from a laser diode emitting up to 300 mW at a wavelength of 1.86 microns. Thermal lesions of varying strength were scanned using an experimental OCT device with about 25 microns lateral and 20 microns axial resolution. Histologic evaluation of the scanned areas was done by polarization microscopy after Sirlus-Red staining, and similar lesions were also analyzed by TEM. RESULTS: Both methods differentiated three damage zones a transition zone, a zone of moderate coagulation, and a central zone of strong coagulation. In the transition zone, increased birefringence was seen in polarization microscopy, which correlated with increased light scattering seen in the OCT images. In the moderately coagulated zone, a decrease in birefringence was associated with an even stronger increase of the OCT signal. In the central zone, a loss of the fibrillar tissue structure was observed, which led to a complete loss of birefringence and a strong reduction of the OCT signal. CONCLUSIONS: Although OCT does not provide the detailed information on thermal changes of tissue seen by the histologic method, it offers information on the extent and degree of tissue changes without preparation artifacts and provides a non-invasive method of immediate and follow-up control of LTK lesions. A quantitative analysis of changes in corneal thickness and curvature is much simpler than by a slit lamp. Time-resolved measurements of corneal light scattering may be used for on-line control of the laser-light dosage during LTK.

Animals↗
PubMed1997

Optical coherence tomography of the human skin.

BACKGROUND: Optical coherence tomography (OCT) is a new diagnostic method for tissue characterization. OBJECTIVE: We investigated normal and pathologic structures in human skin in several locations to evaluate the potential application of this technique to dermatology. METHODS: Based on the principle of low-coherence interferometry, cross-sectional images of the human skin can be obtained in vivo with a high spatial resolution of about 15 microns. Within a penetration depth of 0.5 to 1.5 mm, structures of the stratum corneum, the living epidermis, and the papillary dermis can be distinguished. RESULTS: Different layers could be detected that were differentiated by induction of experimental blisters and by comparison with corresponding histologic sections. Furthermore, OCT images of several skin diseases and tumors were obtained. CONCLUSION: OCT is a promising new imaging method for visualization of morphologic changes of superficial layers of the human skin. It may be useful for noninvasive diagnosis of bullous skin diseases, skin tumors, and in vivo investigation of pharmacologic effects.

Adult↗
PubMed1997

Dose-intense therapy with etoposide, ifosfamide, cisplatin, and epirubicin (VIP-E) in 107 consecutive patients with limited- and extensive-stage non-small-cell lung cancer.

BACKGROUND: We conducted a phase I/II trial to assess the feasibility and activity of combination chemotherapy with etoposide, ifosfamide, cisplatin, and epirubicin in limited-stage (LS, stage I-IIIB) and extensive-stage (ES, stage IV) non-small-cell lung cancer (NSCLC). End-points were treatment-related morbidity and mortality, response rate, duration of response, and survival. PATIENTS AND METHODS: Chemotherapy followed by granulocyte colony-stimulating factor was given at a dose of etoposide (500 mg/m2), ifosfamide (4000 mg/m2), cisplatin (50 mg/m2), and epirubicin (50 mg/m2) (VIP-E) to 107 patients with NSCLC. Twenty-five patients with qualifying responses proceeded to high-dose chemotherapy with autologous peripheral blood stem cell transplantation after etoposide (1500 mg/m2), ifosfamide (12,000 mg/m2), carboplatin (750 mg/m2) and epirubicin (150 mg/m2) (VIC-E) conditioning. RESULTS OF CONVENTIONAL-DOSE VIP-E: 35 of 102 (34%) evaluable patients responded (2 CR's, 33 PR's), 33/102 patients (33%) showed no change (NC); the remainder of patients progressed with therapy (PD). Objective response rate was 68% (4% CR, 64% PR) in LS-NSCLC and 23% (1.4% CR, 21.4% PR) in ES-NSCLC. Median duration of survival was 13 months in LS-NSCLC and 5.5 months in ES-NSCLC. Two-year survival was 26% in LS and 2% in ES-NSCLC. RESULTS OF HIGH-DOSE VIC-E: 23 of 24 evaluable patients improved or maintained prior responses (92%), I patient showed NC. Treatment mortality was 4%. Median duration of survival was 17 months in LS-NSCLC and 10 months in ES-NSCLC. Two-year survival was 30% in LS and 8% in ES-NSCLC. CONCLUSION: Response-rates and survival after conventional-dose VIP-E chemotherapy are comparable to other published trials of combination chemotherapy in NSCLC. Toxicity and mortality is acceptable in limited stage, but unacceptably high in extensive stage NSCLC. Although better response-rates were achieved in the high-dose arm, they did not translate into improved survival. Most stage IV NSCLC-patients will neither benefit from VIP-E conventional dose, nor from VIC-E high dose chemotherapy. Whether selected LS-patients with partial or complete responses to VIP-E induction chemotherapy could benefit from dose intensification in an adjuvant or neo-adjuvant setting remains to be determined.

Adult↗
PubMed1997

The transjugular stent implantation for the treatment of malignant portal and hepatic vein obstruction in cancer patients.

BACKGROUND: The increase in portal vascular resistance is a significant complication of metastatic disease to the liver or locally advanced cancer, e.g., biliary cancer. PATIENTS AND METHODS: This paper describes the successful palliative treatment of two cancer patients with portal hypertension presenting with the symptoms of tense ascites, mesenteric congestion, and severe variceal bleeding. By creating a stenttract between a hepatic vein and a main branch of the portal vein and/or by placing an extendable stent into the portal vein, the transjugular intrahepatic portosystemic stent-shunt (TIPS) technique was used to decompress the portovascular system. RESULTS: The TIPS-technique offers a new, safe and effective palliation for malignant portal hypertension. In both patients, the symptoms of the portal hypertension disappeared after the procedure. This was accompanied by a significant improvement of the patients performance status allowing an early ambulation. CONCLUSION: Our findings demonstrate the feasibility and effectiveness of the TIPS procedure as a minimal invasive treatment for portal vein decompression in selected tumor patients.

Biliary Tract Neoplasms↗
PubMed1997

Dose-intense therapy with etoposide, ifosfamide, cisplatin, and epirubicin (VIP-E) in 100 consecutive patients with limited- and extensive-disease small-cell lung cancer.

BACKGROUND: We conducted a phase I/II trial to assess the feasibility and activity of VIP-E chemotherapy in small-cell lung cancer. End-points were treatment-related morbidity and mortality, response to treatment. duration of response, and survival. PATIENTS AND METHODS: Two cycles of combination chemotherapy followed by granulocyte colony-stimulating factor (G-CSF) were given at a dose of etoposide (500 mg/m2), ifosfamide (4000 mg/m2), cisplatin (50 mg/m2), and epirubicin (50 mg/m2) to 100 consecutive patients with SCLC. Thirty patients (19 with LD, and 11 with ED SCLC) proceeded to VIC-E high-dose chemotherapy with autologous peripheral blood stem cell transplantation (PBSCT) at a cumulative dose of etoposide 1500 mg/m2, ifosfamide 12,000 mg/m2, carboplatin 750 mg/m2 and epirubicin 150 mg/m2 (VIC-E). Surgical resection of primary tumor was attempted at the earliest feasible point. Thoracic irradiation was given after completion of chemotherapy. RESULTS of conventional-dose VIP-E: 97 patients were evaluable for response. Objective response rate was 81% in LD-SCLC (33% CR, 48% PR; excluding patients in surgical CR) and 77% in ED-SCLC (18% CR, 58% PR). Treatment mortality was 2%. Median survival was 19 months in LD-SCLC and 6 months in ED-SCLC. Two-year survival was 36% in LD and 0% in ED SCLC. RESULTS OF HIGH-DOSE VIC-E: All 30 patients improved on or maintained prior responses. Four patients (13%) died of treatment-related complications. Median survival was 26 months in LD-SCLC and 8 months in ED-SCLC. Two-year survival was 53% in LD and 9% in ED SCLC. CONCLUSION: VIP-E chemotherapy is an effective induction therapy for SCLC. Compared with traditional protocols such as ACO or carboplatin/etoposide, response rates are slightly improved, while survival is not different. In the LD SCLC subgroup, high-dose chemotherapy improved response rates and survival, especially for patients in surgical CR prior to high-dose therapy. In ED SCLC, however, higher response-rates did not translate into improved survival. Selected LD-SCLC patients with good partial or complete remissions after prior therapy may benefit from HDC and PBSCT.

Adult↗
PubMed1996

Phase II trial of intravenous endotoxin in patients with colorectal and non-small cell lung cancer.

We report the immunological and clinical results of a phase II trial with intravenously administered highly purified endotoxin (Salmonella abortus equi) in patients with advanced cancer. 15 patients with non-small cell lung cancer and 27 with colorectal cancer were entered into the study. 37 evaluable patients received at least four injections of endotoxin (4 ng/kg body weight) and 1600 mg ibuprofen orally in 2-week intervals. Transient renal (WHO grade 0-1) and hepatic (WHO grade 0-4) toxicities occurred in several patients. Constitutional side-effects such as fever, chills and hypotension could not be prevented completely by pretreatment with ibuprofen. 3 patients in the colorectal cancer group demonstrated objective responses (1 complete remission (CR), 2 partial remission (PR)). The complete remission has been maintained for more than 3 years, while the partial remissions were stable for 7 and 8 months, respectively. Only marginal antitumour effects were seen in the lung cancer group. Tolerance of the macrophage system to the stimulatory effect of endotoxin, as measured by human necrosis factor alpha (TNF-alpha) release into serum, built up after the first administration and remained at a steady-state level after each subsequent injection. In constrast, rising CD4:CD8 ratio and release of tumour necrosis factor beta (TNF-beta) indicated the continuing activation of the lymphocyte system by repetitive injections of endotoxin.

Adult↗
PubMed1996

[In vitro studies on pulsed laser angioplasty in liquid and gaseous medium].

PURPOSE: In a vascular model the mechanisms of a pulsed dye laser working in a liquid and a gaseous environment was tested and documented by means of a high-speed camera. METHODS: The pulse application (630 nm wavelength) on a target of calcified arterial plaque material was detected at intervals of 20 microseconds up to 800 microseconds total time. RESULTS: In water the laser beam created a cavitation bubble which expanded from 0 to 450 microseconds from a radius 0 to 3 mm and collapsed afterwards. The average expansion velocity of the bubble was 80 m/s in the first 20 microseconds and the resulting velocity of the tube model wall was 10 m/s. Compared with gaseous atmosphere there was no bubble and consecutively no wall stress. CONCLUSION: It is obvious that laser angioplasty causes wall stress and destruction of different vascular layers. This might be the initial stimulation for restenosis. In gaseous atmosphere laser angioplasty should be more protective.

Angioplasty, Laser↗
PubMed1996

Iron deficiency in distance runners. A reinvestigation using Fe-labelling and non-invasive liver iron quantification.

In a group of male distance runners, 23 out of 45 athletes showed decreased serum ferritin values (< 35 micrograms). The high prevalence of a typical iron deficiency in runners was confirmed in a subgroup of eight athletes in which the iron metabolism was studied in detail using radio-iron labelling and liver iron quantification. Most of these athletes showed an up-regulated 59Fe absorption and a decreased liver iron concentration as compared to a control group. 59Fe activity in collected samples of stool, urine or sweat was measured sensitively using a shielded high-pure germanium spectrometer. In periods without running, a faecal excretion of 59Fe equivalent to 1.5 ml blood loss/d was observed, which represents the normal iron excretion. Under intensive training or racing conditions, a significant increase up to 4.9-6.6 ml blood loss/day was observed, whereas excretion of 59Fe in urine or sweat was negligible. Thus, gastrointestinal blood loss was the main reason for the slightly negative iron balance in the runners. This confirms earlier studies in the literature using qualitative blood stool testing. A treatment with 100 mg ferrous iron/day for 3 months significantly increased the values for serum ferritin (from 34 +/- 11 to 54 +/- 18 micrograms/l) and liver iron (from 105 +/- 42 to 227 +/- 67 micrograms/g liver).

Adult↗
PubMed1996

Evaluation of caffeine as a test drug for CYP1A2, NAT2 and CYP2E1 phenotyping in man by in vivo versus in vitro correlations.

Caffeine is used to phenotype subjects in vivo for the cytochrome P450 isoforms CYP1A2 and CYP2E1, and for N-acetyltransferase type 2 (NAT2). However, how much of the variation in phenotyping parameters may be attributed to variations in CYP1A2 and CYP2E1 activities has not been determined. Therefore, this study intraindividually compared enzyme activities and/or content in liver samples with pharmacokinetic parameters of caffeine in vivo after administration of a test dose in 25 patients undergoing hepatectomy. Parameters measured in vitro were the high affinity components of caffeine 3-demethylation and phenacetin 0-deethylation, microsomal CYP1A2 and CYP2E1 immunoreactivity, and cytosolic sulfamethazine N-acetylation. Caffeine parameters in vivo included caffeine clearance from plasma and/or saliva, paraxanthine/caffeine ratios in plasma and saliva, plasma theophylline/caffeine ratio, and several metabolite ratios from spot urine sampled 6 h postdose. Correlations between parameters were determined using weighted linear regression analyses. Caffeine clearance and paraxanthine/caffeine ratios correlated most highly to intrinsic clearance of caffeine 3-demethylation and to CYP1A2 immunoreactivity (r= 0.584-0.82), whereas urinary CYP1A2 ratios correlated less strongly with CYP1A2 parameters in vitro. Assignment of acetylator phenotype by urinary NAT2 ratios was concordant with sulfamethazine-N-acetylation in vitro. In contrast to CYP1A2 parameters in vitro, CYP2E1 immunoreactivity was not related to the theophylline/caffeine plasma ratio. CYP1A2 activity, thus, is the major determinant of caffeine clearance and the paraxanthine/caffeine ratios in vivo, of which the saliva ratio 6 h postdose appears as the most advantageous parameter. The results confirm that phenotyping using caffeine provides valid estimates of CYP1A2 and NAT2 activity.

Aged↗
PubMed1995

Complete response of metastatic renal cell carcinoma to low-dose interferon-gamma treatment.

The course of metastatic renal cell carcinoma may be positively influenced by immunotherapeutic agents. We report a case of renal cell carcinoma showing a complete response to once-weekly low-dose s. c. interferon-gamma (IFN gamma) treatment in multiple metastatic sites (lung, chest wall, abdomen, vertebral body), but concomitantly developing a solitary brain metastasis. High initial interleukin-6 (IL-6) levels returned to normal during IFN treatment suggesting that IFN gamma may have interrupted an autocrine IL-6/IL-6-receptor loop of the tumor cells. The duration of complete remission in the extracerebral sites is now 46+ months. IFN gamma may be less active beyond the blood/brain barrier.

C-Reactive Protein↗
PubMed1995

Liver iron stores in patients with secondary haemosiderosis under iron chelation therapy with deferoxamine or deferiprone.

Total body iron stores including liver and spleen iron were assessed by non-invasive SQUID biomagnetometry. The liver iron concentration was measured in groups of patients with beta-thalassaemia major or other posttransfusional siderosis under treatment with the oral iron chelator deferiprone (n = 19) and/or with parenteral deferoxamine (n = 33). An interquartile range for liver iron concentrations of 1680-4470 micrograms/g liver was found in these patients. In both groups a poor correlation between liver iron and serum ferritin values was observed. Repeated measurements of liver and spleen iron concentrations as well as determination of liver and spleen volume by sonography were performed in six patients under continuous deferiprone treatment for 3-15 months. In this group detailed information was obtained on the whole body iron store (5-36g) and the iron excretion rates (14-34 mg/d) for each patient. As indicated by decreasing liver iron concentrations, five out of six subjects showed a negative iron balance (2-13 mg/d). Conventional measurements of both serum ferritin and urine iron excretion gave fluctuating results, thus being only of limited use in the control of iron depletion therapy. The non-invasive biomagnetic liver iron quantification is a precise and clinically verified technique which offers more direct information on the long-term efficacy of an iron depletion therapy than the hitherto used methods. This technique may be of use in the clinical evaluation of new oral iron chelators.

Adult↗
PubMed1995

Endotoxin (Salmonella abortus equi) in cancer patients. Clinical and immunological findings.

1. LPS phase I trial revealed MTD I of 1.0 ng/kg body weight and MTD II of 5.0 ng/kg body weight, the latter given together with ibuprofen (1,600 mg). 2. LPS phase II trial, using 4,0 ng/kg body weight plus ibuprofen in a biweekly schedule didn't show any response in patients with non-small cell lung cancer but 1 CR and 2 PR (13% response rate) in colorectal cancer patients. 3. The LPS tolerance is specific for each cytokine and mediator in regard to the kinetic and degree of its development. INF-gamma prevents the tolerance development to several cytokines with the exception of IL-8. 4. No tolerance was found in cell adhesion, phospholipase A2, and soluble TNF receptor I and II. Priming of ex vivo cytokine production of cytokines was found in mononuclear cells. 5. Synthetic LPS partial structure SDZ-MRL 953 (I) induces a cytokine pattern, which is profoundedly different from that of LPS, (II) with an inverse TNF to G-CSF relation, (III) is (without any ibuprofen treatment) remarkably low toxic, (IV) and downregulates the TNF-response to LPS markedly.

Carcinoma, Non-Small-Cell Lung↗
PubMed1994

Discordant adaptation of human peritoneal macrophages to stimulation by lipopolysaccharide and the synthetic lipid A analogue SDZ MRL 953. Down-regulation of TNF-alpha and IL-6 is paralleled by an up-regulation of IL-1 beta and granulocyte colony-stimulating factor expression.

Human peritoneal macrophages were exposed to increasing doses of LPS or a synthetic lipid A analogue (SDZ MRL 953) and production of the cytokines IL-1 beta, IL-6, TNF-alpha, and G-CSF was assessed at the protein and mRNA level. Cells were also prestimulated with low doses of LPS and SDZ MRL 953 to study their adaptation to a secondary challenge with high doses of LPS. The ability of macrophages to produce high levels of TNF-alpha and IL-6 after stimulation with LPS could be relieved almost completely by preincubating cells with low doses of LPS. Decreases of TNF-alpha and IL-6 production resulted from inhibition of gene transcription and/or changes in mRNA stability, as transcript levels of these cytokines were down-modulated by the process of LPS adaptation. Surprisingly, however, adapted cells were able to synthesize even larger quantities of G-CSF and IL-1 beta when exposed to a secondary LPS challenge. mRNA levels of the adapted cells remained unaltered for IL-1 beta, but were slightly increased for G-CSF as assessed by Northern blot analysis. High doses of the synthetic lipid A analogue SDZ MRL 953 were also able to adapt macrophages to a secondary LPS challenge by down-regulating TNF-alpha and IL-6 production, whereas priming secretion of G-CSF and IL-1 beta as well. We describe here the discordant adaptation of human peritoneal macrophages to a secondary LPS stimulus in vitro. These findings appear to have ramifications for the in vivo endotoxin response during inflammation and also Gram-negative septicemia.

Dinoprostone↗
PubMed1994

Liver iron quantification: studies in aqueous iron solutions, iron overloaded rats, and patients with hereditary hemochromatosis.

For the noninvasive liver iron quantification by MRI in human iron overload diseases, fundamental proton relaxation mechanisms were studied in aqueous solutions with ferritin and other iron compounds, in experimentally iron overloaded rats, and in patients with iron overload diseases. MR-relaxation rates as a function of iron concentrations in the range of 0-7.5 mg Fe/g aqueous iron solutions, 0-5.4 mg Fe/g rat liver in vivo, and 0.16-4.9 mg Fe/g human liver in vivo were determined from multi- and sets of single-spin echo sequences (1.5 T imager). As predicted by theory, transverse relaxation rates (1/T2) in aqueous iron solutions, in liver tissue of rats, and in human liver tissue increased linearly with the iron concentration. A preliminary calibration for the liver iron quantification by MRI was performed from in vivo measurements of liver 1/T2-relaxation rates and liver iron quantification by atomic absorption spectroscopy in biopsies from 13 patients. With the single spin-echo method, precise in vivo liver iron quantification in humans also above 2.0 mg Fe/g liver tissue (T2 < 15 ms) should be accomplished on any imager with shortest spin-echo time available, at least TE < 20 ms.

Adult↗