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Biomedical subjects

C Maurer

Publications and source records attributed to C Maurer.

At least 37 records · Page 2Linked to original sources
PubMed2000

Vestibular, visual, and somatosensory contributions to human control of upright stance.

We investigated the changes of human posture control of upright stance which occur when vestibular cues (VEST) are absent and visual and somatosensory orientation cues (VIS, SOM) are removed. Postural responses to sinusoidal tilts of a motion platform in the sagittal plane (+/-2 degrees, f=0.05, 0.1, 0.2 and 0.4 Hz) were studied in normal subjects (Ns) and patients with bilateral vestibular loss (Ps). We found that absence of VEST (Ps, visual reference) and removal of VIS (Ns, no visual reference) had little effect on stabilization of upright body posture in space. In the absence of both VEST and VIS (Ps, no visual reference) somatosensory graviception still provided some information on body orientation in space at 0.05 and 0.1 Hz. However, at the higher frequencies Ps qualitatively changed their behavior; they then tended to actively align their bodies with respect to the motion platform. The findings confirm predictions of a novel postural control model.

Cues↗
PubMed2000

An integrated approach to structural genomics.

Structural genomics aims at determining a set of protein structures that will represent all domain folds present in the biosphere. These structures can be used as the basis for the homology modelling of the majority of all remaining protein domains or, indeed, proteins. Structural genomics therefore promises to provide a comprehensive structural description of the protein universe. To achieve this, a broad scientific effort is required. The Berlin-based "Protein Structure Factory" (PSF) plans to contribute to this effort by setting up a local infrastructure for the low-cost, high-throughput analysis of soluble human proteins. In close collaboration with the German Human Genome Project (DHGP) protein-coding genes will be expressed in Escherichia coli or yeast. Affinity-tagged proteins will be purified semi-automatically for biophysical characterization and structure analysis by X-ray diffraction methods and NMR spectroscopy. In all steps of the structure analysis process, possibilities for automation, parallelization and standardization will be explored. Major new facilities that are created for the PSF include a robotic station for large-scale protein crystallization, an NMR center and an experimental station for protein crystallography at the synchrotron storage ring BESSY II in Berlin.

Crystallography, X-Ray↗
PubMed2000

[Characteristics and specificities of cystic fibrosis in adults: evolutive disease of childhood or recently diagnosed disease?].

We have studied the characteristics of 202 cystic fibrosis adult patients, all with chronic respiratory symptoms, with a median age of 27 yrs (18 to 55 yrs) and a male predominance (56%). At genetic analysis, delta F508 homozygotes were 41%, delta F508 heterozygotes 42% and 17% had no delta F508. The respiratory disease was more severe and complications were more frequent in adults: hemoptysis in 14%, pneumothorax in 15%, lung transplantation in 25 patients. Chronic bronchial colonisation with Pseudomonas aeruginosa, in 76% of patients, contributed to making treatments more severe because of antibiotic i.v. courses and nebulised antibiotics. Respiratory function showed a mean FVC of 62 +/- 22% and a mean FEVI of 48 +/- 94%. External pancreatic insufficiency was found in 83%, diabetes in 14%. Intestinal occlusion syndromes were observed in 11% of patients and hepatic cirrhosis in 8%. In spite of the severity of the respiratory disease, theses patients succeeded in social and occupational insertion; 62% were independent, 18% had children and 77% were working or studying. Analysis of the patients according to age at diagnosis showed that, in 38 patients diagnosed after the age of 18 yrs, the respiratory disease was less severe, pancreatic insufficiency and non-respiratory complications were less frequent (34% had pancreatic insufficiency, 5% had diabetes and none had cirrhosis). This may partly be due to the presence of milder CFTR mutations. In conclusion, cystic fibrosis in adulthood frequently looks like an evolutive form of cystic fibrosis in childhood. Nevertheless, some late diagnosed forms in adults, with better prognosis, have been recently identified.

Adolescent↗
PubMed1999

[Hepatopulmonary syndrome].

ANAMNESIS: We report about a 60-year-old woman with hepatopulmonary syndrome. The patient suffered from progressive dyspnea and liver cirrhosis following viral hepatitis C, acquired through blood transfusion 30 years ago. EXAMINATION RESULTS: Remarkable were clinical signs of chronic liver disease (cutaneous spider naevi, palmar erythema) and signs of chronic respiratory failure (clubbing) with platypnea. Arterial pO2 was 33 mm Hg under 41 O2/min nasal oxygen supplement and improved to 74 mm Hg under 81 O2/min. Arterial pO2 deteriorated in upright position (orthodeoxia). Contrast enhanced two-dimensional transthoracic echocardiography showed a delayed microbubble opacification in the left heart chambers (without atrial or ventricular septal defect), suggesting pulmonary vascular dilatations. Perfusion scan with macroaggregated albumin labelled with technetium-99m showed uptake over thyroid, kidneys, liver, and spleen suggesting an abnormal passage through the pulmonary vascular bed. The radiological examination with chest radiography and high resolution computer tomography revealed no signs of interstitial lung disease. The pulmonary artery angiography showed neither anatomical shunts nor malformations. DIAGNOSIS: The final diagnosis was hepatopulmonary syndrome Type 1. TREATMENT/FOLLOW-UP: The patient underwent liver transplantation with following good function of the liver graft. After 6 months the patient presented in a much better general condition, but with persisting severe hypoxemia whereas the spider naevi disappeared completely. One year after the liver transplantation in the perfusion scan the uptake over thyroid, kidneys, liver, and spleen was absent. The orthodeoxia and hypoxemia improved evidently. From that we conclude that the pulmonary vascular dilatations diminished after liver transplantation.

Diagnosis, Differential↗
PubMed1999

Water pollution and human health in China.

China's extraordinary economic growth, industrialization, and urbanization, coupled with inadequate investment in basic water supply and treatment infrastructure, have resulted in widespread water pollution. In China today approximately 700 million people--over half the population--consume drinking water contaminated with levels of animal and human excreta that exceed maximum permissible levels by as much as 86% in rural areas and 28% in urban areas. By the year 2000, the volume of wastewater produced could double from 1990 levels to almost 78 billion tons. These are alarming trends with potentially serious consequences for human health. This paper reviews and analyzes recent Chinese reports on public health and water resources to shed light on what recent trends imply for China's environmental risk transition. This paper has two major conclusions. First, the critical deficits in basic water supply and sewage treatment infrastructure have increased the risk of exposure to infectious and parasitic disease and to a growing volume of industrial chemicals, heavy metals, and algal toxins. Second, the lack of coordination between environmental and public health objectives, a complex and fragmented system to manage water resources, and the general treatment of water as a common property resource mean that the water quality and quantity problems observed as well as the health threats identified are likely to become more acute.

Agriculture↗
PubMed1999

Sanglifehrins A, B, C and D, novel cyclophilin-binding compounds isolated from Streptomyces sp. A92-308110. I. Taxonomy, fermentation, isolation and biological activity.

A novel class of macrolides for which the name sanglifehrins is proposed, has been discovered from actinomycete strains based on their high affinity binding for cyclophilin A (CypA), an immunophilin originally identified as a cytosolic protein binding cyclosporin A (CsA). The sanglifehrins were produced by Streptomyces sp. A92-308110. They were isolated and purified by extraction and several chromatographic, activity-guided steps. Sanglifehrins A and B exhibit a 10 to approximately 20 fold higher affinity for CypA than CsA, whereas the affinity of sanglifehrins C and D for CypA is comparable to that of CsA. Sanglifehrins exhibit a lower immunosuppressive activity than CsA when tested in the mixed lymphocyte reaction. Their in vitro activity indicates that they belong to a novel class of immunosuppressants.

Animals↗
PubMed1998

Activation of the serine proteinase system in chronic kidney rejection.

BACKGROUND: Activation of the serine proteinase system is an important mechanism that contributes to tissue remodeling. In the present study, we analyzed the expression of urokinase plasminogen activator (uPA), urokinase plasminogen activator receptor (uPAR), and plasminogen activator inhibitor type 1 (PAI-1) in samples of chronically rejected human kidneys. METHODS: Using Northern blot analysis, immunohistochemistry, and a uPA activity assay, specimens from 10 chronically rejected kidneys and 10 normal kidney samples were analyzed. RESULTS: By Northern blot analysis, the expression of uPAR and PAI-1 mRNA was 2.9-fold (P<0.05) and 2.3-fold (P<0.05) increased in chronically rejected kidney samples, respectively, compared with normal controls. In contrast, uPA mRNA levels in chronically rejected kidneys were comparable to those in the normal controls. Immunohistochemical analysis in normal kidneys showed weak immunostaining of uPA, moderate to intense uPAR and PAI-1 immunostaining in proximal tubules, and moderate immunostaining in distal tubules, but no signal in the glomeruli or cortical vessels. A similar staining pattern was found in the distal and proximal tubules in rejected kidney tissue samples. However, in the rejected kidneys, the number of tubules was markedly reduced. In addition, within the glomeruli of rejected kidney samples, there was positive immunostaining for uPA, uPAR, and PAI-1 in the mesangial cells, but negative staining in most of the endothelial cells, whereas the normal kidneys revealed no immunoreactivity in these structures. CONCLUSION: The demonstrated up-regulation of uPA/uPAR/PAI-1 in chronic renal rejection is consistent with the plasminogen/plasmin system contributing to tissue remodeling in this disorder. These factors might activate latent transforming growth factor-betas, which have been reported to be enhanced in this disorder, contributing to the generation of the extracellular matrix.

Aged↗
PubMed1998

[Adjuvant therapy of colorectal carcinoma--1998 status].

Colorectal cancer is the second leading cause of cancer death in western countries. The prognosis is strongly correlated to the TNM-staging system and patients with stage T3-4 and/or node positive disease are at high risk for locoregional or distant relapse. It is now widely accepted that patients with node positive colon cancer should be offered postoperative adjuvant chemotherapy. Evidence is accumulating that six months' adjuvant fluorouracil plus leucovorin is equivalent to twelve months' fluorouracil and levamisole, which reduces cancer related deaths by more than 30%. Other adjuvant treatment approaches are perioperative regional chemotherapy or monoclonal antibody treatment, and the results of trials comparing these different treatment options alone or in combination are eagerly awaited. In rectal cancer, the risk of locoregional recurrence can be more than 50% and this event is associated with a deterimental effect on quality of life. The technique of mesorectal excision and the use of radiotherapy, alone or in combination with chemotherapy, have evolved as the most important measures for prevention of locoregional recurrence. In addition, chemotherapy has proven to be effective in reducing metastatic relapse and prolonging survival. The timing of radiotherapy (pre- versus postoperative) and the optimal combination of chemotherapy with radiation are presently important research issues in resected rectal cancer. In both colon and rectal cancer, a common theme emerging from the experience of the last few decades is that administration of dose-intensive fluorouracil is key for the success of adjuvant treatment.

Antineoplastic Agents↗
PubMed1998

KAI1 is unchanged in metastatic and nonmetastatic esophageal and gastric cancers.

Down-regulation of KAI1 mRNA expression has been shown to be associated with the formation of metastases or disease progression in pancreatic cancer. Whether KAI1 possesses similar characteristics in other malignancies of the gastrointestinal tract is not known. Here, we compared the patterns of KAI1 mRNA expression in 41 esophageal cancers and 35 stomach cancers to assess whether KAI1 might also be of biological relevance in the metastatic ability of these tumors. By Northern blot analysis, KAI1 mRNA levels ranged widely in both normal and cancerous esophageal and gastric tissue samples, with no statistical differences. No association between KAI1 mRNA expression and tumor stage or tumor differentiation was seen in these tumors. In addition, KAI1 mRNA expression was similar in primary esophageal and gastric cancer samples with or without metastases. By in situ hybridization, KAI1 mRNA expression was evident in the cytoplasm of most squamous epithelial cells in the normal esophagus and in nonmucosal epithelial cells of the normal stomach. The staining intensity in the esophageal and gastric cancer cells was similar to that in the normal controls. This differential pattern of KAI1 mRNA expression in esophageal and gastric cancers in comparison to pancreatic cancer indicates that KAI1 seems to influence the potential of gastrointestinal cancer cells to metastasize differently. In esophageal and gastric cancers, the formation of metastases is not dependent on the reduction of KAI1 in the cancer cells.

Adult↗
PubMed1998

Eye-head coordination in labyrinthine-defective humans.

Eye-head coordination during saccadic gaze shifts normally relies on vestibular information. A vestibulo-saccadic reflex (VSR) is thought to reduce the eye-in-head saccade to account for current head movement, and the vestibulo-ocular reflex (VOR) stabilizes postsaccadic gaze while the head movement is still going on. Acute bilateral loss of vestibular function is known to cause overshoot of gaze saccades and postsaccadic instability. We asked how patients suffering from chronic vestibular loss adapt to this situation. Eye and head movements were recorded from six patients and six normal control subjects. Subjects tracked a random sequence of horizontal target steps, with their heads (1) fixed in primary position, (2) free to move, or (3) preadjusted to different head-to-target offsets (to provoke head movements of different amplitudes). Patients made later and smaller head movements than normals and accepted correspondingly larger eye eccentricities. Targeting accuracy, in terms of the mean of the signed gaze error, was better in patients than in normals. However, unlike in normals, the errors of patients exhibited a large scatter and included many overshoots. These overshoots cannot be attributed to the loss of VSR because they also occurred when the head was not moving and were diminished when large head movements were provoked. Patients' postsaccadic stability was, on average, almost as good as that of normals, but the individual responses again showed a large scatter. Also, there were many cases of inappropriate postsaccadic slow eye movements, e.g., in the absence of concurrent head movements, and correction saccades, e.g., although gaze was already on target. Performance in patients was affected only marginally when large head movements were provoked. Except for the larger lag of the head upon the eye, the temporal coupling of eye and head movements in patients was similar to that in normals. Our findings show that patients with chronic vestibular loss regain the ability to make functionally appropriate gaze saccades. We assume, in line with previous work, three main compensatory mechanisms: a head movement efference copy, an active cervico-ocular reflex (COR), and a preprogrammed backsliding of the eyes. However, the large trial-to-trial variability of targeting accuracy and postsaccadic stability indicates that the saccadic gaze system of patients does not regain the high precision that is observed in normals and which appears to require a vestibular head-in-space signal. Moreover, this variability also permeates their gaze performance in the absence of head movements.

Adaptation, Physiological↗
PubMed1998

What is straight ahead to a patient with torticollis?

Vestibular and neck proprioceptive signals are known to be used in judging the locations of objects in space and relative to the body. Given that these signals are asymmetric in patients with spasmodic torticollis, one would expect such patients to have abnormal spatial perception. We tested this idea by measuring patients' perception of visual straight ahead (VSA) under various conditions: with the body in its primary position, i.e. with the head and trunk as closely aligned as possible, and after well defined passive rotations of the head and/or trunk. In the primary body position, patients' VSA direction showed considerable variations which were similar, however, to those of normal subjects; it was independent of torticollis direction, of the head torque it produced, and of the weak spontaneous nystagmus recorded in seven of the 10 patients. After whole-body rotations, i.e. where head and trunk underwent the same motion, the VSA was shifted in both patients and normal subjects, and in both groups the shift was symmetrical after rotations to the right or left. After motions where the trunk rotated under the stationary head (neck proprioceptive stimulation) or the head on the stationary trunk (combined vestibular and neck stimulus), the VSAs of normal subjects coincided rather well with their head midsagittal planes, whereas the VSAs of patients were shifted considerably towards the trunk, again in a symmetrical way. We suggest two mechanisms to explain the findings in patients: (i) a central compensation which restores symmetry of the afferent inflow in the patients (unlike the motor efference); (ii) shifting of the reference for the VSA from the head towards the trunk, because the trunk is a more reliable egocentric reference than the head in the patients. Our findings do not support the assumption that asymmetries in afferent inflow are responsible for the asymmetry of motor output in spasmodic torticollis.

Adult↗
PubMed1998

Risk factor assessment of endoscopically removed malignant colorectal polyps.

BACKGROUND: Malignant colorectal polyps are defined as endoscopically removed polyps with cancerous tissue which has invaded the submucosa. Various histological criteria exist for managing these patients. AIMS: To determine the significance of histological findings of patients with malignant polyps. METHODS: Five pathologists reviewed the specimens of 85 patients initially diagnosed with malignant polyps. High risk malignant polyps were defined as having one of the following: incomplete polypectomy, a margin not clearly cancer-free, lymphatic or venous invasion, or grade III carcinoma. Adverse outcome was defined as residual cancer in a resection specimen and local or metastatic recurrence in the follow up period (mean 67 months). RESULTS: Malignant polyps were confirmed in 70 cases. In the 32 low risk malignant polyps, no adverse outcomes occurred; 16 (42%) of the 38 patients with high risk polyps had adverse outcomes (p<0.001). Independent adverse risk factors were incomplete polypectomy and a resected margin not clearly cancer-free; all other risk factors were only associated with adverse outcome when in combination. CONCLUSION: As no patients with low risk malignant polyps had adverse outcomes, polypectomy alone seems sufficient for these cases. In the high risk group, surgery is recommended when either of the two independent risk factors, incomplete polypectomy or a resection margin not clearly cancer-free, is present or if there is a combination of other risk factors. As lymphatic or venous invasion or grade III cancer did not have an adverse outcome when the sole risk factor, operations in such cases should be individually assessed on the basis of surgical risk.

Adult↗
PubMed1998

A large duplication cyst of the stomach in an adult presenting as pancreatic pseudocyst.

Intestinal duplication is a rare congenital disease. It appears throughout the gastrointestinal tract, especially in the ileum. Here we describe the rare case of a gastric duplication cyst in a 59-year-old patient. Diagnostic findings and surgical therapy are discussed. Gastric duplications in adults are extremely rare, and diagnosis is often missed. Symptoms are unspecified pain in the upper abdomen, vomiting and fever, with some patients having weight loss. Complications are rare. Chronic infections and ruptures are described. For diagnosis, CT scan with oral contrast is preferred. Endoscopy is negative in most cases. Therapy is surgery. Local excision of a small wall of gastric mucosa is sufficient in most cases, but sometimes a subtotal gastrectomy is necessary.

Cysts↗
PubMed1997

[Study by the Professional Organization of German Transfusion Physicians on epidemiology of HIV- and hepatitis infections in blood donors].

The frequency of the seromarkers of HIV, HCV, and HBV in the donor population from all donor centers in Germany became available from the multicenter study of the transfusion services. From these data the risk of virus transmission by blood products can be estimated at 1:1 million for HIV and 1:50,000 for HBV. For HCV, preliminary data indicate the risk for Germany in less than 1:20,000. The risk is even lower, with less than 1:200,000 when calculated from seroconversion data of a rural donor population. The safety of blood products has been very much improved due to the continuous donor selection over the last years and by the epidemiologic situation in Germany.

Blood Donors↗
PubMed1996

[Febrile state and pleural effusion].

A 42 year old patient was admitted for evaluation of a febrile state and left thoracic pain. Chest-X-ray revealed a left-sided pleural effusion nonresponsive to a trial antibiotic treatment. The subsequent punction yielded sterile exudate without microorganisms or malignant cells. Tuberculostatic treatment for suspected tuberculosis lead to exacerbation and hospitalization. Antibodies against native DNA first became detectable during the further course. Together with anamnestic information about fatigue, hair loss and the family history revealing two sisters touched by the disease, the diagnosis of systemic lupus erythematodes was made. Corticosteroids led to rapid improvement with complete resolution of the pleural effusion.

Adult↗
PubMed1996

Gastric microcirculatory changes during gastric tube formation: assessment with laser Doppler flowmetry.

Poor perfusion of the gastric substitute in esophageal replacement frequently causes anastomotic break down. In this in vivo study we assessed gastric microperfusion before, during, and after gastric tube formation by means of laser Doppler flowmetry in 11 patients undergoing esophagectomy for esophageal cancer. Baseline blood flux along the greater curvature was 323 +/- 57, 167 +/- 28, and 190 +/- 44 perfusion units (PU) and along the lesser curvature 222 +/- 44 and 227 +/- 46 PU. Blood flux was significantly higher in close proximity to tumor-infiltrated areas (819 +/- 172 and 879 +/- 119 PU, P < 0.03 and P < 0.008 compared to normal stomach). Dissection of the gastrocolic ligament and the left gastric artery reduced gastric blood flux along the greater curvature to 69 +/- 21, 79 +/- 19, and 155 +/- 61 PU. Elongation and transformation of the stomach to a gastric tube further reduced blood flux in the stomach especially at the fundus. In this study laser Doppler flowmetry was a valuable tool to assess microcirculatory changes during gastric tube formation as well as pathological blood flow in tumor bearing areas of the stomach in vivo. Quantification of the perfusion of gastric tubes in esophageal replacement might help prevent ischemia-induced anastomotic breakdown.

Adenocarcinoma↗
PubMed1996

Correction or transfer of immunodeficiency due to TNF-LT alpha deletion by bone marrow transplantation.

BACKGROUND: Mice with inactivated tumor necrosis factor (TNF) and lymphotoxin alpha (LT alpha) genes have profound abnormalities of the immune system including lymphocytosis, lack of lymph nodes, undifferentiated spleen, hypoimmunoglobulinaemia, and defective Ig class switch. Here, we asked whether this phenotype is due to incompetent lymphohemopoietic progenitors or to a defective environment. MATERIALS AND METHODS: Lethally irradiated TNF-LT alpha-deficient and wild-type mice received bone marrow cells from either TNF-LT alpha-deficient or wild-type mice. The reconstitution and transfer of the phenotype was followed by morphological and functional analyses. RESULTS: Bone marrow cells from wild-type mice restored the synthesis of TNF and LT alpha, corrected the splenic microarchitecture, normalized the lymphocyte counts in the circulation, and repopulated the lamina propria with IgA-producing plasma cells of TNF-LT alpha-deficient mice. Furthermore, the formation of germinal centers in the spleen and the defective Ig class switch in response to a T-cell dependent antigen was corrected, while no lymph nodes were formed. Conversely, the TNF-LT alpha phenotype could be transferred to wild-type mice by bone marrow transplantation after lethal irradiation. CONCLUSIONS: These data demonstrate that most TNF- and LT alpha-producing cells are bone marrow derived and radiosensitive, and that the immunodeficiency due to TNF-LT alpha deletion can be corrected to a large extent by normal bone marrow cell transplantation. The genotype of the donor bone marrow cells determines the functional and structural phenotype of the TNF-LT alpha-deficient adult murine host, with the exception of lymph node formation. These findings may have therapeutic implications for the restoration of genetically defined immunodeficiencies in humans.

Animals↗