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Biomedical subjects

J Lotz

Publications and source records attributed to J Lotz.

At least 55 records · Page 3Linked to original sources
PubMed1997

Vitamin metabolism in patients with a Mainz pouch I: long-term followup.

PURPOSE: We assessed whether creation of the Mainz pouch I, which requires 24 to 36 cm. of terminal ileum and 12 cm. of ascending colon including the ileocecal valve, leads to metabolic disturbances. MATERIALS AND METHODS: In 137 patients the levels of vitamins A, B1, B2, B6, B12, D and E, folic and bile acids, ammonia, and intracorpuscular vitamin B12 and folic acid were evaluated and a red blood count was performed. Patients were divided into children and adults, and into 3 groups according to number of years after surgery (2 or less, more than 2 to 4 and more than 4). RESULTS: In all patients the levels of vitamins A, B1, B2, B6, D and E, folic and bile acids, and ammonia as well as red blood count were within normal ranges. In the 51 children there was no significant decrease in vitamin B12 postoperatively. In the 86 adults mean serum vitamin B12 plus or minus standard deviation decreased significantly from 402 +/- 182 ng./l. during the first 2 years postoperatively to 292 +/- 204 ng./l. after year 4 (normal 240 to 1,100). There was no significant decrease in intracorpuscular vitamin B12 during this period. CONCLUSIONS: In addition to regular examinations, the determination of vitamin B12 levels 4 years after Mainz pouch diversion is mandatory. It remains unclear whether substitution is necessary. However, substitution is easy to achieve and even less expensive than the regular determination of vitamin B12.

Adult↗
PubMed1997

[Aspects relevant for abdominal surgery of attempted suicide].

In this retrospective study of 24 patients who were treated at our clinic during the last 22 years after having attempted suicide, we evaluated aspects concerning abdominal- and transplantation surgery. There was a predominance of "hard" (70%) versus "soft" (30%) methods for suicide attempt. Intra-abdominal injuries resulting from attempted suicide by stabbing or shooting should lead to laparotomy-the prognosis is then good. Surgical treatment after intoxication, especially caustic ingestion, depends on endoscopic and clinical findings. The highly increased rates of suicide in patients with end-stage renal disease can be reduced significantly by kidney transplantation. The risk of suicide after transplantation is further diminished with improved immunosuppressive treatment. Only in a few cases there is an indication for liver transplantation-in some cases of fulminant hepatic failure caused by self-administered paracetamol overdose. Auxiliary liver transplantation may then be considered.

Abdominal Injuries↗
PubMed1996

Magnetic resonance imaging of trabecular bone structure in the distal radius: relationship with X-ray tomographic microscopy and biomechanics.

The contribution of trabecular bone structure to bone strength is of considerable interest in the study of osteoporosis and other disorders characterized by changes in the skeletal system. Magnetic resonance (MR) imaging of trabecular bone has emerged as a promising technique for assessing trabecular bone structure. In this in vitro study we compare the measures of trabecular structure obtained using MR imaging and higher-resolution X-ray tomographic microscopy (XTM) imaging of cubes from human distal radii. The XTM image resolution is similar to that obtained from histomorphometric sections (18 microns isotropic), while the MR images are obtained at a resolution comparable to that achievable in vivo (156 x 156 x 300 microns). Standard histomorphometric measures, such as trabecular bone area fraction (synonymous with BV/TV), trabecular width, trabecular spacing and trabecular number, texture-related measures and three-dimensional connectivity (first Betti number/volume) of the trabecular network have been derived from these images. The variation in these parameters as a function of resolution, and the relationship between the structural parameters, bone mineral density and the elastic modulus are also examined. In MR images, because the resolution is comparable to the trabecular dimensions, partial volume effects occur, which complicate the segmentation of the image into bone and marrow phases. Using a standardized thresholding criterion for all images we find that there is an overestimation of trabecular bone area fraction (approximately 3 times), trabecular width (approximately 3 times), fractal dimension (approximately 1.4 times) and first Betti number/ volume (approximately 10 times), and an underestimation of trabecular spacing (approximately 1.6 times) in the MR images compared with the 18-microns XTM images. However, even for a factor of 9 difference in spatial resolution, the differences in the morphological trabecular structure measures ranged from a factor of 1.4 to 3.0. We have found that trabecular width, area fraction, number, fractal dimension and Betti number/volume measured from the XTM and MR images increases, while trabecular spacing decreases, as the bone mineral density and elastic modulus increase. A preliminary bivariate analysis showed that in addition to bone mineral density alone, the Betti number, trabecular number and spacing contributed to the prediction of the elastic modulus. This preliminary study indicates that measures of trabecular bone structure using MR imaging may play a role in the study of osteoporosis.

Absorptiometry, Photon↗
PubMed1996

Growth hormone substitution in growth hormone-deficient adults: effects on collagen type I synthesis and skin thickness.

Growth hormone stimulates collagen type I synthesis. Collagen type I is a common matrix compound in a large number of connective tissues. The aim of our study was to prove whether a stimulation of collagen type I synthesis might be accompanied by a deposition of collagen type I in the skin (cutis). Twenty growth hormone-deficient hypopituitary patients were included in a randomised, double-blind, placebo controlled, prospective, twelve-month study (eighteen patients assessable at the end of the study). The patients were treated with recombinant human growth hormone 0.25 U/kg/week subdivided in daily subcutaneous injections beginning with half the dosage during the first four weeks. During the first six months half of the patients were treated with placebo. PICP, the indicator of collagen type I synthesis, was increased after six months of therapy when compared to placebo. Skin thickness measured by ultrasound at the forearm and mechanically at the dorsum of the hand with strong compression of the skin both increased significantly following growth hormone substitution. Our data indicate that the stimulation of collagen type I synthesis by growth hormone substitution is followed by a deposition of collagen type I in the skin.

Adult↗
PubMed1996

Endothelin-1 modulates the expression of adhesion molecules on fibroblast-like synovial cells (FLS).

Endothelin-1 is known to possess various biological properties. In the present study we have investigated the effects of Endothelin-1 (Et-1) on the expression of adhesion molecules ICAM-1, VCAM-1 and CD-44 by fibroblast-like synoviocytes. Cultured fibroblast-like synoviocytes were treated with Et-1 in the absence or presence of C1306, a specific endothelin-A-receptor antagonist. Cell surface expression of ICAM-1, VCAM-1 and CD-44 was determined by immunofluorescence studies, Cyto-ELISA and FACS-analysis. ICAM-1, VCAM-1 and CD-44 were constitutively expressed on cultured FLS. After incubation with Et-1 the expression of ICAM-1, VCAM-1 and CD-44 increased. The level of expression of adhesion molecules after Et-1 stimulation was similar to cytokine mediated effects (IL-1 beta, TNF-alpha). IL-1 beta showed the strongest stimulatory effect on the expression of ICAM-1, TNF-alpha preferentially induced the expression of VCAM-1 and CD-44, and Et-1 strongly stimulated the upregulation of CD-44 expression. In addition, Et-1 enhanced significantly the IL-1 beta mediated upregulation of VCAM-1 expression, whereas TNF-alpha mediated expression of VCAM-1 was downregulated by Et-1. Furthermore, the Et-1 induced expression of adhesion molecules on FLS was mediated via the endothelin-A-receptor (EtA-receptor), since C-1306, a selective endothelin-A-receptor antagonist, could block this effect. These results indicate that Et-1 has stimulating effects on FLS in vitro. The expression of adhesion molecules can be upregulated by Et-1 similar to proinflammatory cytokines. The modulating effect of Et-1 can be inhibited by the pretreatment with a selective EtA-receptor antagonist. Thus, Et-1 may have immunoregulatory functions in the recruitment of cells infiltrating the inflamed tissue.

Cell Adhesion Molecules↗
PubMed1995

Evaluation of an automated chromogenic substrate assay for the rapid determination of hirudin in plasma.

A fully mechanized chromogenic substrate assay method for the rapid and specific determination of recombinant hirudin (r-hirudin) in citrated plasma on clinical chemistry analyzers (Hitachi 911 and Cobas Mira) is described. In a first step, 12 microliters sample volume is mixed with the chromogenic substrate. Due to the almost immediate action of hirudin the inhibitory reaction and the cleavage of the substrate is started simultaneously when bovine thrombin is added in excess. This excludes interferences by antithrombin III or heparin cofactor II. The change in absorbance/min is recorded at 405 nm. The measuring range is about 0.2-4.0 mg/l r-hirudin on both analyzers. Precision is characterized by intraassay coefficients of variation between 0.63% and 2.78% on the Hitachi 911 and 1.51% and 7.84% on the Cobas Mira, respectively and interassay coefficients of variation of 3.57% to 9.15% (Hitachi 911) and 3.72% to 12.99% (Cobas Mira) for the same r-hirudin plasma concentrations. The described determination of r-hirudin correlates well with an enzyme linked immunosorbent assay method for r-hirudin (Hitachi 911: r = 0.964, y = 0.978x + 0.038, n = 323; Cobas Mira: r = 0.964, y = 0.959x-0.003, n = 323).

Animals↗
PubMed1995

Biochemical bone markers compared with bone density measurement by dual energy X-ray absorptiometry.

In contrast to medical imaging, the biochemical markers allow a more frequent determination and are not as invasive as histomorphometric methods. We investigated biochemical markers of type I collagen compared with bone density measurements in 85 females between 41 and 89 years of age (median: 57 years). The bone density measurements were performed by dual energy X-ray absorptiometry (DXA) on the lumbar spine (L1-4). The bone density measurements were stated as a percentage of the norm. All patients were divided into three groups: I = <80%; II = 80-130%; III = >120%. Based on this classification the median concentration of the I-carboxyterminal propeptide of type I collagen in serum (S-PICP) as an anabolic marker of type-I collagen increased significantly with rising bone density: I 65.0 micrograms/liter (interquartile range: 52.1-78.0 micrograms/liter); II 85.9 micrograms/liter (52.1-115.5 micrograms/liter); III 81.4 micrograms/liter (62.0-101.0 micrograms/liter);P < 0.05. The concentration of urinary pyridinolines (U-PYR) as a marker for degradation of type I collagen decreased. The I-carboxyterminal telopeptide (S-ICTP) and osteocalcin (S-BGP) did not change. The multivariate regression analysis showed no relationship between between bone density and biochemical bone markers. Only the age significantly correlated negatively with bone density measurement. For a better assessment of type I collagen metabolism we created a "b-quotient" by dividing the sum of S-PICP and S-BGP by U-PYR. The median b-quotient increased significantly: I 1.55 (0.97-2.04); II 2.09 (1.57-2.86): III 2.46 (1.58-3.22); P < 0.05. Changes in bone metabolism cannot be identified by the determination of a single marker. However, the improved biochemical diagnostic measurement using the b-quotient may provide early information about the progression of a metabolic disorder within the interval of imaging.

Absorptiometry, Photon↗
PubMed1994

Laboratory control of minimal heparinization during haemodialysis in patients with a risk of haemorrhage.

For patients undergoing dialysis with a high risk of haemorrhage there is no standardized procedure for anticoagulation during extracorporeal circulation. Minimal heparinization with a dose equivalent to half that used for chronic haemodialysis was employed in 49 patients (125 haemodialyses) performed after operative interventions (83.3%), after haemorrhagic events (5.2%) and after invasive investigations (11.5%). Using a biocompatible membrane and a low molecular weight heparin (bolus dose 500-1300 U; continuous infusion 100-400 U) it was possible to complete haemodialysis in 74 cases (Group 0) without clots appearing in the venous bubble trap of the tubing system. In 30 cases (Group 1) only small clots were detected at the end of haemodialysis, and in 13 cases (Group 2) larger clots (exceeding a diameter of 1 cm) were found. In eight cases (Group 3) partial or complete clot formation occurred in the tubing. No haemorrhagic complications were observed. Anti-Xa activity, thrombin-antithrombin III complex (TAT) and D-dimer were determined before haemodialysis, 2 h after the start of haemodialysis and on completion of the procedure. The anti-Xa activities ranged between < 0.2 and 0.56 U/ml. In contrast, at 2 h there were significant differences (P < 0.05) in the TAT concentrations between Group 0 and the other groups, as well as between Group 1 and Group 2 and 3. Significant differences (P < 0.05) in D-dimer levels occurred only at the end of haemodialysis. Minimal heparinization in haemodialysis is a practicable alternative in patients with a high risk of haemorrhage and extended coagulation monitoring is helpful in adjusting heparin dosage.

Adult↗
PubMed1993

Immunonephelometric determination of the C4b-binding protein.

A fully mechanised immunonephelometric method for the rapid and specific determination of C4b-binding protein (C4b-BP) in citrated plasma is described. The method utilizes commercially available rabbit antiserum against human C4b-BP and a nephelometer analyser. A single determination can be performed within 6 min, requiring 80 microliters sample volume. The measuring range is about 10 to 200% of normal C4b-BP. Precision is characterized by intraassay coefficients of variation between 1.5% and 2.8%, and interassay coefficients of variation between 4.0% and 4.6% for the same C4b-BP concentrations. The nephelometry of C4b-BP was correlated with electroimmunodiffusion (Laurell technique; r = 0.863, y = 0.909x+7.091, n = 79). C4b-BP concentrations (143%, 96-223%; median and 2.5th-97.5th percentile) from 83 subjects with increased inflammation markers C-reactive protein (> 10 mg/l), and fibrinogen (> 4.5 g/l) showing significantly higher C4b-BP concentrations compared to 151 obviously healthy subjects (97%, 68-141%; p < 0.001). In contrast to 81 patients with therapeutic heparinisation (90%, 60-131%) significant decreased concentrations were found in 90 subjects under oral anticoagulant therapy (OAT) in the stable state (78%, 44-125%; p < 0.001). Depending on different INR levels (< 2.5, n = 40: 71%, 63-85%; > 2.5, n = 50: 81%, 68-92%; median and 25th-75th percentile) no significant differences of C4b-BP concentrations could be measured.

Administration, Oral↗
PubMed1993

Influence of blood sampling from venipunctures and catheter systems on serial determinations of prothrombin activation fragment 1 + 2 and thrombin-antithrombin III complex.

To evaluate the influence of different blood sampling techniques on test results of thrombin-antithrombin III complex (TAT) and prothrombin fragment 1 + 2 (F1 + 2) serial determinations were performed. In six groups of nonrandomized patients (ten patients each) the concentrations of the coagulation markers of blood samples from central catheters (internal jugular, caval, Shaldon, pulmonary artery) and peripheral cannulas (17G and 18G) were compared with those of blood samples obtained simultaneously from direct venipunctures of the contralateral arm. Medians and 25th-75th percentiles of TAT and F1 + 2 concentrations of plasmas obtained from central catheters were not different from those taken from venipunctures. When delta mean values (catheter - venipuncture) were calculated negative results were obtained, indicating lower concentrations measured from blood sampled through central catheters with the exception of blood that taken from Shaldon catheters. Only for TAT concentrations significantly were lower values measured in blood samples taken from internal jugular catheters when compared with blood samples obtained from direct venipunctures. Significantly higher TAT concentrations were determined in blood samples obtained from Shaldon catheters. For both coagulation markers correlations were found between concentrations in blood samples from central catheters and venipunctures. In blood samples taken from peripheral venous cannulas only F1 + 2 concentrations correlated with the concentrations found in samples from direct venipuncture. In contrast to F1 + 2, TAT concentrations measured from blood samples via peripheral cannulas were determined significantly higher than those taken from direct venipunctures.(ABSTRACT TRUNCATED AT 250 WORDS)

Antithrombin III↗
PubMed1992

Monitoring prothrombin fragment 1 + 2 during initiation of oral anticoagulant therapy after intracoronary stenting.

Patients with intracoronary stent implantation are treated with aggressive anticoagulant and antiplatelet therapy consisting of high-dose heparin, phenprocoumon, acetylsalicylic acid, dipyridamole, and the infusion of dextran to prevent a subacute thrombotic occlusion of the stented segment. In an effort to optimize this treatment by reducing both imminent bleeding complications and subacute thrombotic occlusion, the concentrations of prothrombin fragment 1 + 2 (F 1 + 2) were determined after intracoronary Palmaz-Schatz stent implantation in 19 consecutive patients. The F 1 + 2 concentrations after stent implantation and before the initiation of oral anticoagulant therapy (OAT) were 0.35 nm/l and 0.25-0.53 nm/l (median and 25th-75th percentile), versus 0.74 nm/l and 0.52-0.78 nm/l, in healthy subjects and 0.61 nm/l and 0.30-1.02 nm/l in 15 patients with ongoing proximal DVT. Nine days after initiation of OAT, F 1 + 2 concentrations in both patient groups had not yet reached levels observed in patients with OAT in the stable state (0.16 nm/l, 0.12-0.26 nm/l; n = 76; P less than 0.0001 compared with healthy subjects; INR 2.0-4.5). Despite an INR greater than 2.0, accompanying heparinization was terminated on day 9. In two stented patients a minor bleeding complication arose after the removal of the arterial catheter. Subacute thrombotic occlusions were not observed. Since F 1 + 2 concentrations did not exceed the upper limit of normal range (1.11 nm/l) in any of the 19 patients, the therapeutic regimen was not changed. Monitoring F 1 + 2 may thus be helpful in introducing a more individual treatment if aggressive anticoagulation has to be performed.

Administration, Oral↗
PubMed1991

[Infrared casting temperature control of the induction centrifuge casting exemplary in the non-precious dental alloy Wiron 88].

A temperature-dependent, IR-controlled casting technology for the non-precious dental alloy Wiron 88 (Bego) is presented and compared with a traditional procedure. The new casting allows the production of cast objects with favourable and reproducible material properties. Compared with the commonly used technology hardness, grain size and susceptibility to corrosion could be reduced. Texture after casting was found to be homogeneous. The procedure presented meets the requirements for a modern casting technology and be adapted to older automatic casating devices.

Aluminum↗
PubMed1990

[The microstructure and corrosive properties of the nonferrous casting alloys Gisadent NCA, NCS 1 and KCM 83 before and after casting].

Nonprecious alloys (NEM) applied in dental practice often show widely differing material properties after casting. This is caused by subjective and objective differences in manufacturing of these alloys with a given technology as well as by varying composition and structure of the alloys within and in between different lots. For homogeneous composition of crude specimens technologically caused variance of casting condition itself leads to considerable differentiation of casting results. If the original state of crude alloy forms is very different then there will be a levelling out and/or increase of scattering of material parameters after casting. Optimized computed-controlled casting technology in combination with defined muffle ring size could result in reproducible casting results.

Chromium Alloys↗
PubMed1988

IFN-mediated induction of MHC antigen expression on human keratinocytes and its influence on in vitro alloimmune responses.

The MHC Ag expression on the surface of keratinocytes is altered after treatment with IFN. IFN-gamma induces, as expected, a strong increase in class I MHC Ag expression as well as de novo expression of class II MHC Ag, whereas IFN-alpha 2 only slightly increases class I MHC Ag and does not induce keratinocytes to express class II MHC Ag. We used untreated and IFN-pretreated keratinocytes as stimulators and also as targets to study whether IFN-induced MHC Ag changes would alter the immunogenicity of keratinocytes in alloimmune responses. It was found that class II MHC Ag-carrying keratinocytes were unable to induce the proliferation of resting lymphocytes, but did stimulate T blasts. Untreated keratinocytes were virtually resistant to the lysis by classical CTL but became susceptible after exposure to IFN-gamma, but not IFN-alpha 2 at physiologic doses. These data demonstrate mechanisms by which the release of IFN-gamma might contribute to the development of disease such as the graft vs host disease.

Cell Division↗
PubMed1988

Neurocysticercosis: correlative pathomorphology and MR imaging.

CT and MR images of 32 patients with neurocysticercosis were correlated with pathomorphology. Gross morphological features of cystic larvae, complex arachnoid cysts, granulomatous abscesses, basal meningitis and mineralised nodules correlated closely with the images obtained, especially on MR, where resolution permitted visualisation of larval protoscolices. Our material indicates three forms of the natural history of neurocysticercosis related chiefly to anatomic location, and provides details of the evolution of large, complex arachnoid cysts.

Brain↗