Biomedical subjects

H Bartels

Publications and source records attributed to H Bartels.

At least 37 records · Page 2Linked to original sources

PubMed2001

[Postoperative complications--what is often? What is rare?].

The postoperative course after major (elective) digestive surgical procedures was prospectively analysed in 5693 patients. Postoperative complications were documented in 553 patients (9.7%). There were general complications (not related to surgery) in 97 patients (17.5%) and surgical complications (related to surgery) in 456 patients (82.5%). The most frequent surgical complication was abdominal sepsis in 72.1% followed by postoperative bleeding (17.1%) and others (10.7%). The leading cause for abdominal sepsis was anastomotic leakage in 207 patients (70.2%). Bedside diagnostic procedures like sonography, analysis of fluid drainage and endoscopy could identify the underlying problem of abdominal sepsis in 60.9% of cases. The mortality rate of all studied patients was (113/5693 patients) 1.9%.

Critical Care↗

PubMed2000

Structure of functionally activated small ribosomal subunit at 3.3 angstroms resolution.

The small ribosomal subunit performs the decoding of genetic information during translation. The structure of that from Thermus thermophilus shows that the decoding center, which positions mRNA and three tRNAs, is constructed entirely of RNA. The entrance to the mRNA channel will encircle the message when a latch-like contact closes and contributes to processivity and fidelity. Extended RNA helical elements that run longitudinally through the body transmit structural changes, correlating events at the particle's far end with the cycle of mRNA translocation at the decoding region. 96% of the nucleotides were traced and the main fold of all proteins was determined. The latter are either peripheral or appear to serve as linkers. Some may assist the directionality of translocation.

Base Pairing↗

PubMed2000

Risk analysis in esophageal surgery.

The postoperative mortality after esophagectomy still remains a major factor influencing the prognosis of esophageal cancer and largely depends on the patient's preoperative physiological status. A composite scoring system was developed to predict the risk of esophagectomy, based on quantitative assessment of preoperatively available physiological parameters. The scoring system was reviewed retrospectively on operated patients and evaluated prospectively in two subsequent patient groups. An initial retrospective multivariate analysis of 432 esophagectomy patients identified a compromised general status (p = 0.001) and poor cardiac (p < 0.001), hepatic (p < 0.05), and respiratory (p < 0.05) functions as independent predictors of a fatal postoperative course. Based on the relative risks associated with individual impaired organ functions--general status 3.6, cardiac function 2.8, hepatic function 2.1, pulmonary function 1.7--a composite risk score was established. A prospective study in 121 patients confirmed that this composite scoring system provides better identification of high-risk patients than does any of the individual parameters alone. Including this composite score into the process of patient selection and choice of procedure resulted in a decrease of postoperative mortality from 9.4% (52/553) to 1.2% (4/323) (p = 0.001). The risk of death after esophagectomy for esophageal cancer can be objectively assessed prior to surgery and quantified by a composite risk score. This score provides a useful tool in refining the criteria of patient selection for resection and choice of procedure, and markedly reduces postoperative mortality when applied prospectively.

Esophageal Neoplasms↗

PubMed2000

[Immune paralysis of T-lymphocytes and monocytes in postoperative abdominal sepsis. Correlation of immune function with survival].

In vitro functions of stimulated peripheral T cells and monocytes were investigate in patients experiencing sepsis following major visceral surgery. Cell culture supernatants were analyzed by ELISA for IL-2, IFN-gamma, IL-4, IL-10, TNF-alpha, IL-1 beta, and IL-12p40. In addition, monocyte HLA class II expression was determined by flow cytometry. T cell secretion of IL-2, TNF-alpha, and in part IFN-gamma (but not IL-4) was significantly diminished in non-survivors throughout the entire course of sepsis, compared to controls and sepsis survivors. Production of IL-1 beta and IL-12 p40 by monocytes was strongly reduced in both survivors and non-survivors at the onset of sepsis. Persistence of depressed monocyte cytokine secretion correlated with lethality. Thus, overall suppression of cytokine production by T cells and monocytes was already observed at the beginning of postoperative sepsis. HLA class II expression by monocytes exhibited a strong and sustained down-regulation with no significant differences between sepsis survivors and non-survivors. In summary, suppression of both T cell and monocyte functions develops early during postoperative sepsis. Recovery of immune functions and severity of immune defects are associated with outcome.

Cytokines↗

PubMed2000

Adjuvant treatment of clinical stage I seminoma: is a single course of carboplatin sufficient?

OBJECTIVES: Adjuvant radiotherapy produces excellent disease-free rates in clinical Stage I seminoma. However, concern is growing about side effects and late hazards of this treatment. Carboplatin has been suggested to supplant radiotherapy. To date, there is little experience with this drug in the adjuvant treatment of seminoma. In particular, it is unclear whether one or two courses should be administered. METHODS: In a nonrandomized study, 125 patients with pure clinical Stage I seminoma were given adjuvant carboplatin treatment (400 mg/m2). Ninety-three patients received one course and 32 two courses. The median follow-up time was 48 months. To assess gonadal toxicity, serial measurements of follicle-stimulating hormone (FSH) levels were done. To assess myelotoxicity, platelet counts at 3 and 4 weeks after treatment were monitored. RESULTS: There were no relapses after two courses of carboplatin. After one course of carboplatin, eight relapses occurred (8.6%; 95% confidence interval [CI] 3.79% to 16.2%). All the relapses were located in the para-aortic region, and all the patients were rescued with cisplatin-based chemotherapy. The median time to recurrence was 16 months. The 5-year actuarial progression-free survival rate after one course was 91.1% (95% CI 85.25% to 97.01%). Younger patients (age groups: less than 30 years and 31 to 38 years) had relapses more frequently (P = 0.038) than those in the older age group (greater than 38 years). After 3 weeks, 32% of the patients had platelet counts below 150/nL. The median FSH level increased immediately after treatment, reaching a peak of 13.6 U/L. After 20 months, the median FSH level had returned to the normal range. CONCLUSIONS: One adjuvant course of carboplatin was associated with low myelotoxicity and low gonadal toxicity; however, the recurrence rate was almost 9% and thus unsatisfactory. After two courses of carboplatin, no relapse was observed. Thus, the two-course regimen of carboplatin appears to be equivalent to radiotherapy, and because of its favorable toxicity profile, this regimen should be investigated in randomized trials.

Adult↗

PubMed2000

Ischemic spinal cord syndrome after transthoracic esophagectomy: two cases of a rare neurologic complication.

Anterior spinal artery syndrome (ASAS) is a rare complication after surgery of the thoracic or abdominal aorta. The sulco commissuralis syndrome represents a partial or incomplete ASAS. We report two cases of ischemic spinal cord syndromes after transthoracic esophagectomy. This represents a prevalence of this syndrome of 0.2% in more than 1000 consecutive esophagectomies performed at our institution. Patient 1 developed an ASAS on the first day after esophagectomy. Patient 2 showed the pathognomonic clinical signs associated with sulco commissuralis syndrome after an asymptomatic window. In both patients, the extent of the neurologic symptoms initially improved but then remained unchanged for the rest of the follow-up of 9 and 12 months. Although the prognosis of neurologic syndromes resulting from spinal cord infarction is poor, preoperative tests to identify patients at risk appear not to be justified because of the very low incidence of these syndromes after esophagectomy and the poor sensitivity and specificity of currently available diagnostic modalities. However, the possibility of ischemic spinal cord syndrome should be kept in mind when patients present with neurologic symptoms after esophagectomy.

Aged↗

PubMed2000

Translocation of Yersinia entrocolitica across reconstituted intestinal epithelial monolayers is triggered by Yersinia invasin binding to beta1 integrins apically expressed on M-like cells.

Yersinia enterocolitica cross the intestinal epithelium via translocation through M cells, which are located in the follicle-associated epithelium (FAE) of Peyer's patches (PP). To investigate the molecular basis of this process, studies were performed using a recently developed in vitro model, in which the enterocyte-like cell line Caco-2 and PP lymphocytes are co-cultured in order to establish FAE-like structures including M cells. Here, we demonstrate that Y. enterocolitica does not adhere significantly to the apical membrane of differentiated enterocyte-like Caco-2 cells that express binding sites for Ulex europaeus agglutinin (UEA)-1. In contrast, Y. enterocolitica adhered to, and was internalized by, cells that lacked UEA-1 binding sites and displayed a disorganized brush border. These cells were considered to be converted to M-like cells. Further analysis revealed that part of these cells expressed beta1 integrins at their apical surface and, as revealed by comparison of wild-type and mutant strains, interacted with invasin of Y. enterocolitica. Consistently, anti-beta1 integrin antibodies significantly inhibited internalization of inv-expressing yersiniae. Experiments with Yersinia mutant strains deficient in YadA or Yop secretion revealed that these virulence factors play a minor role in this process. After internalization, yersiniae were transported within LAMP-1-negative vacuoles to, and released at, the basal surface. Internalization and transport of yersiniae was inhibited by cytochalasin D, suggesting that F-actin assembly is required for this process. These results provide direct evidence that expression of beta1 integrins at the apical surface of M cells enables interaction with the invasin of Y. enterocolitica, and thereby initiates internalization and translocation of bacteria.

Adhesins, Bacterial↗

PubMed2000

Sepsis after major visceral surgery is associated with sustained and interferon-gamma-resistant defects of monocyte cytokine production.

BACKGROUND: Recent clinical trials failed to demonstrate beneficial effects of anti-inflammatory sepsis therapy. The present study therefore asked the following questions: Is there evidence for immunosuppression during postoperative sepsis? When, during the septic course, may immunosuppression develop? Can defective cellular functions be restored by in vitro treatment with interferon-gamma (IFN-gamma)? METHODS: The study included 35 patients with sepsis after major visceral surgery and 85 control patients. Monocyte secretion of interleukin (IL)-1 beta, IL-12 p40 and p70, IL-18, tumor necrosing factor, and IL-10 with or without IFN-gamma treatment and its correlation with the course and outcome of postoperative sepsis were determined. RESULTS: Postoperative sepsis was associated with an immediate defect of endotoxin-stimulated monocyte production of IL-12 p40, IL-1 beta, and IL-10 in both surviving and nonsurviving patients. During the final phase of postoperative sepsis, a significant recovery of IL-12 p40 and IL-1 beta secretion, but not of IL-10 production, correlated with survival. Despite the exposure of monocytes in vitro to IFN-gamma for 16 hours, the production of the biologically active IL-12 p70 heterodimer was severely suppressed both in survivors and nonsurvivors, although the secretion of the p40 subunit was restored. In contrast, IFN-gamma treatment resulted in a significant suppression of monocyte IL-1 beta production in all patient subgroups. Alterations of monocyte tumor necrosing factor secretion were not observed. The production of IL-18 was below the limits of detection in all samples. CONCLUSIONS: Postoperative sepsis was associated with immediate monocyte defects that affected both pro- and anti-inflammatory cytokine secretion, which suggests that immunosuppression is a primary rather than a compensatory response to a septic challenge. Sepsis survival correlated with the recovery of the proinflammatory, but not the anti-inflammatory, response. The treatment of monocytes with IFN-gamma did not reconstitute defective proinflammatory cytokine production.

Cytokines↗

PubMed2000

Deciduoid pleural mesothelioma affecting a young female without prior asbestos exposure.

Pleural mesothelioma is commonly associated to asbestos exposure. A 40-year-old woman is described who presented with shortness of breath. She had a smoking history but no history of asbestos exposure. Chest radiography and computed tomography showed a large tumour on the right lower lung. An open pleural biopsy was performed. A metastatic adenocarcinoma of the pleura was primarily diagnosed. The tumour progressed and after surgical excision an accurate histological and immunohistochemical examination was performed. It revealed a pleural mesothelioma with a deciduoid differentiation that has not been described before.

Adenocarcinoma↗

PubMed2000

Targeting exposed RNA regions in crystals of the small ribosomal subunits at medium resolution.

Within the framework of ribosomal crystallography, the small subunits are being analyzed, using crystals diffracting to 3 A resolution. The medium resolution electron density map of this subunit, obtained by multiple isomorphous replacement, show recognizable morphologies, strikingly similar to the functional active conformer of the small ribosomal subunit. It contains elongated dense features, traceable as RNA chains as well as globular regions into which the structures determined for isolated ribosomal proteins, or other known structural motifs were fitted. To facilitate unbiased map interpretation, metal clusters are being covalently attached either to the surface of the subunits or to DNA oligomers complementary to exposed ribosomal RNA. Two surface cysteines and the 3' end of the 16S ribosomal RNA have been localized. Targeting several additional RNA regions shed light on their relative exposure and confirmed previous studies concerning their functional relevance.

Crystallography, X-Ray↗

PubMed1999

The small ribosomal subunit from Thermus thermophilus at 4.5 A resolution: pattern fittings and the identification of a functional site.

The electron density map of the small ribosomal subunit from Thermus thermophilus, constructed at 4.5 A resolution, shows the recognizable morphology of this particle, as well as structural features that were interpreted as ribosomal RNA and proteins. Unbiased assignments, carried out by quantitative covalent binding of heavy atom compounds at predetermined sites, led to the localization of the surface of the ribosomal protein S13 at a position compatible with previous assignments, whereas the surface of S11 was localized at a distance of about twice its diameter from the site suggested for its center by neutron scattering. Proteins S5 and S7, whose structures have been determined crystallographically, were visually placed in the map with no alterations in their conformations. Regions suitable to host the fold of protein S15 were detected in several positions, all at a significant distance from the location of this protein in the neutron scattering map. Targeting the 16S RNA region, where mRNA docks to allow the formation of the initiation complex by a mercurated mRNA analog, led to the characterization of its vicinity.

Base Sequence↗

PubMed1999

Clinicopathogenetic significance of chromosomal abnormalities in patients with blastic peripheral B-cell lymphoma. Kiel-Wien-Lymphoma Study Group.

So far, reproducible histomorphologic and immunological criteria to distinguish clinicopathologic subtypes of blastic peripheral B-cell non-Hodgkin's lymphoma (BBCL), especially centroblastic (cb) and immunoblastic (ib) lymphomas, for daily diagnostic use are still lacking. Therefore, we correlated the cytogenetic findings in 126 patients with BBCL with histopathologic diagnoses. Subclassification of cb and ib lymphomas relied on the criteria defined in the updated Kiel classification; these subtypes are also listed in the Revised European-American Lymphoma (REAL) classification and in a preliminary report on the newly established World Health Organization classification, to investigate their clinical significance. Moreover, we performed a multivariate analysis to compare the prognostic significance of cytogenetic findings with the International Index. There were significant differences in the frequency of chromosome aberrations between different BBCL subtypes: t(8;14) was predominantly present in Burkitt's lymphomas, t(14;18) in centroblastic lymphomas, deletions in 8q and 14q, changes of 4q and losses of chromosome 10 in immunoblastic lymphomas; t(11;14) was restricted to blastoid mantle cell lymphomas and associated with a poor prognosis. In cb lymphomas, deletions in 1q42-qter, duplications in 1q23-32, trisomy 5, and changes of 15q were identified as independent prognostic factors. In ib lymphomas, changes of 7q and 8q had stronger impact on survival than the International Index. These findings underline that Burkitt's, cb, ib, and blastoid mantle-cell lymphoma are biologically distinct and clinically relevant entities and that cytogenetic findings can be helpful to subtype BBCL.

Biomarkers, Tumor↗

PubMed1999

Metal compounds as tools for the construction and the interpretation of medium-resolution maps of ribosomal particles.

Procedures were developed exploiting organometallic clusters and coordination compounds in combination with heavy metal salts for derivatization of ribosomal crystals. These enabled the construction of multiple isomorphous replacement (MIR) and multiple isomorphous replacement combined with anomalous scattering medium-resolution electron density maps for the ribosomal particles that yield the crystals diffracting to the highest resolution, 3 A, of the large subunit from Haloarcula marismortui and the small subunit from Thermus thermophilus. The first steps in the interpretation of the 7. 3-A MIR map of the small subunit were made with the aid of a tetrairidium cluster that was covalently attached to exposed sulfhydryls on the particle's surface prior to crystallization. The positions of these sulfhydryls were localized in difference Fourier maps that were constructed with the MIR phases.

Animals↗

PubMed1998

Crystallographic studies on the ribosome, a large macromolecular assembly exhibiting severe nonisomorphism, extreme beam sensitivity and no internal symmetry.

Crystals, diffracting best to around 3 A, have been grown from intact large and small ribosomal subunits. The bright synchrotron radiation necessary for the collection of the higher-resolution X-ray diffraction data introduces significant decay even at cryo temperatures. Nevertheless, owing to the reasonable isomorphism of the recently improved crystals of the small ribosomal subunits, reliable phases have been extracted at medium resolution (5-6 A) and an interpretable five-derivative MIR map has been constructed. For the crystals of the large subunits, however, the situation is more complicated because at higher resolution (2.7-7 A) they suffer from substantial radiation sensitivity, a low level of isomorphism, instability of the longest unit-cell axis and nonisotropic mosaicity. The 8 A MIR map, constructed to gain insight into this unusual system, may provide feasible reasoning for the odd combination of the properties of these crystals as well as hints for future improvement. Parallel efforts, in which electron-microscopy-reconstructed images are being exploited for molecular-replacement studies, are also discussed.

Animals↗

PubMed1998

Increased susceptibility to postoperative sepsis in patients with impaired monocyte IL-12 production.

IL-12 is a potent immunoregulatory cytokine that is essential for the development of protective immunity, as demonstrated by numerous animal models of infection. Here, we provide evidence for a critical role of IL-12 in human sepsis. The results of a prospective study of 184 patients undergoing major elective surgery of the upper and lower gastrointestinal tract revealed that, in contrast to patients showing uneventful recovery, monocyte IL-12 production was severely and selectively impaired in patients developing postoperative sepsis. Moreover, the extent of monocyte IL-12 suppression correlated with the severity of postoperative sepsis. Monocyte IL-12 secretion was suppressed before surgery and remained low until the onset of sepsis. Therefore, the suppression of IL-12 secretion preceded the onset of postoperative sepsis but did not occur as a consequence of major surgery. In contrast, IL-1beta production was only reduced during the late postoperative course in patients developing postoperative sepsis, and TNF-alpha release was even increased at different time intervals before the onset of sepsis. Thus, reduced IL-12 release does not reflect a general defect in monocyte cytokine production. Consequently, these results establish a critical role for IL-12 in early resistance to postoperative infection and may allow for the development of novel therapeutic strategies designed to stimulate host defense mechanisms and to reduce the incidence and severity of septic complications.

Aged↗

PubMed1998

Simple, rapid and sensitive determination of protionamide in human serum by high-performance liquid chromatography.

A simple high-performance liquid chromatography method has been developed that allows the sensitive determination of protionamide (2-n-propyl-pyridine-4-carboxylic acid thioamide, PTH) in human serum. After pretreatment of the serum with trichloroacetic acid (TCA) and centrifugation the supernatants were neutralized using NaHCO3. PTH was separated on a Kromasil 100 C4 column (acetonitrile-sodium tetraborate buffer pH 8-dibutylamine) and determined photometrically at 291 nm. The lower limit of quantification for 300 microl serum precipitated with 60 microl TCA and injection of 50 microl was 27 microg/l and linearity was observed up to 15 mg/l.

Antitubercular Agents↗

PubMed1998

[Carbohydrate-deficient transferrin (CDT) as preoperative alcohol marker in surgical risk patients].

In a prospective study the preoperative risk of alcohol addiction was evaluated in 46 patients with squamous cell carcinoma of the esophagus. In all patients the alcohol marker carbohydrate-deficient transferrin (CDT) was measured prior to esophagectomy and correlated with the incidence of postoperative withdrawal symptoms (yes/no) and the postoperative course (good/moderate/poor/fatal). Withdrawal symptoms were more frequently observed in cases of elevated CDT values (median of CDT with withdrawal 17.0 U/l vs without withdrawal 10.7 U/l; P = 0.0006). CDT values were significantly increased in case of a complicated postoperative course (median of CDT for moderate/poor/fatal postoperative course 14.0 U/l vs good course 10.8 U/l; P = 0.02). The CDT value correlated (P = 0.04) with the patient's history of preoperative alcohol consumption (normal/increased/high). In a multivariate logistic regression analysis CDT and preoperative alcohol consumption were independent parameters to predict significantly the postoperative course and withdrawal. The sensitivity was 71.4% and the specificity 84.4% selecting the parameter "postoperative withdrawal" and a CDT cut-off point of < 15.3 U/l. CDT can effectively identify patients with high alcohol consumption prior to esophagectomy.

Alcohol Withdrawal Delirium↗

PubMed1998

Categorization of the mitochondria-rich cells in the gill epithelium of the freshwater phases in the life cycle of lampreys

The distribution and ultrastructure of the mitochondria-rich (MR) cells in the gills of larval (ammocoetes) and adult lampreys (Petromyzon marinus and Geotria australis) have been studied. One type of MR cell, which is found only in ammocoetes, occurs in groups on and between gill lamellae. Freeze-fracture replicas show that the apical membrane of this ammocoete MR cell contains globular particles. The second type of MR cell, which is present in both ammocoetes and adults in freshwater, is located between lamellae and at the base of the filament. This cell usually occurs singly and is typically intercalated between ammocoete MR cells in larval lampreys and between pavement cells and pavement and chloride cells in adult lampreys. It contains rod-shaped particles in either the apical membrane (subtype A) or, far less frequently, the lateral membrane (subtype B) and in membranes of cytoplasmic vesicles and tubules. These features characterize this intercalated MR cell as a member of a group of MR cells that are also found in urinary epithelia of tetrapods and the amphibian epidermis, where they are involved in H+ and HCO3- secretion. Because this type of MR cell disappears when the young adult lamprey enters the sea and reappears immediately after the fully grown adult re-enters freshwater on its spawning run, it is presumably essential for osmoregulation in freshwater. On the basis of electrophysiological studies on frog skin, it is proposed that the subtype A of the branchial intercalated MR cell of lampreys provides the driving force for the Na+ uptake by active H+ secretion. By analogy with urinary epithelia, the subtype B cells may exchange Cl- for HCO3-.

Journal Article↗