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Biomedical subjects

H Hoffmann

Publications and source records attributed to H Hoffmann.

At least 37 records · Page 2Linked to original sources
PubMed2004

Low-temperature investigation of the growth mechanism of alkylsiloxane self-assembled monolayers.

The growth behavior of self-assembled monolayer films strongly depends on parameters such as solvent, water concentration in the solvent, substrate type, and deposition method. A further parameter, the temperature, is of particular importance. It has been found that growth kinetics, size, and shape of the structures obtained strongly depend on the deposition temperature. Thus, exact adjustment and control of the solution temperature is of crucial importance for investigation of deposition mechanisms. The development of a temperature control unit has been the basis for a series of experiments on deposition of octadecyltrichlorosilane (OTS) on silicon wafers to study the influence of temperature on growth kinetics and film structure. Characterization of the films was performed with ellipsometry and atomic-force microscopy. It has been found that octadecylsiloxane (ODS) island sizes decrease with increasing temperature. Furthermore, a characteristic temperature exists above which increasingly disordered deposition occurs. At low temperatures (5-10 degrees C) smaller dot-like features are observed besides larger fractally shaped islands characteristic for self-assembly growth of ODS films. Our results indicate that these small dot-like features originate from ordered aggregates in the adsorption solution and that they are the precursors of the formation of larger islands. However, they can only be observed at low temperatures, because at room temperature they coalesce quickly to form larger units, due to the high surface mobility.

Cold Temperature↗
PubMed2004

[Surgery in non-small cell lung cancer of the superior sulcus: results of a combined preoperative and postoperative irradiation regime].

UNLABELLED: Due to local invasion of the chest wall, patients with non small cell carcinoma (NSCLC) of the superior sulcus have been treated mainly by the Paulson regime with radiotherapy followed by surgical resection. Recent published data on the use of concurrent irradiation and chemotherapy followed by surgical resection seemed very promising. The aim of the present study was to determine the value and benefit of a combined preoperative and postoperative radiotherapy regime (Sandwich irradiation), and which factors predict prognosis following resection. PATIENTS AND METHODS: Between 1986 and 2003, 64 patients with non-small cell carcinoma of the superior sulcus were managed in our department. 28 underwent surgical resection with combined preoperative 40 Gy and postoperative 20 Gy external beam radiotherapy. Time to death was calculated using the method of Kaplan and Meier. Survival after surgery was the end point of the study. The association of factors to end of life end points was analyzed using the log-rank test for univariate analysis. Median follow up was 13.1 months. RESULTS: The actuarial 5-year-survival for the overall population was 30.2 %. For surgically-rendered complete resection (CR) patients with no mediastinal lymph node metastases, the 5-year-survival-rate was 53.2 %. The 30-day-mortality-rate was 0 %. Most significant prognostic factors were the mediastinal lymph node involvement and the stage of the disease. CONCLUSIONS: Results of this retrospective study show that patients with non-small cell carcinoma of the superior sulcus can experience a long-term survival which is well comparative to other patients with NSCLC. Surgical resection with a combined preoperative and postoperative radiotherapy regime is well accepted. Special care should be taken in patient selection to identify patients with advanced stage of the disease and mediastinal lymph node metastases.

Adenocarcinoma↗
PubMed2004

Morgagni hernia in adults: results in 7 patients.

OBJECTIVE: Morgagni's hernia is a relatively uncommon diaphragmatic hernia with a potential for considerable morbidity, if the diagnosis is delayed or missed. This review of cases of Morgagni's hernia was undertaken in order to emphasize methods of diagnosis and treatment. METHODS: From 1992 through 2002, seven patients with Morgagni's hernia (5 right, 2 left) were surgically treated at our hospital. We investigated the patients preoperatively including chest roentgenogram, chest CT scan, and contrast studies of the upper gastrointestinal tract. Operative repair was accomplished with the transabdominal or transthoracic approach. Basic spirometric tests had been carried out on patients presented for elective surgery. RESULTS: The majority of patients experienced dyspnea and two patients presented with acute abdomen due to peritonitis. Diagnosis for Morgagni's hernia was made preoperatively in all but one patient. In cases with uncertain diagnosis or peritonitis, a transabdominal approach was preferred. One patient had died of septic multi-organ failure in the early postoperative course. Following elective repair of Morgagni's hernia, improvement in basic spirometric values was seen. CONCLUSIONS: We conclude that repair for Morgagni's hernia can be performed safely and effectively by using different surgical approaches. The risk of progression and incarceration makes clinical awareness, early diagnosis, and surgical treatment warranted. Improvement in lung function can be expected postoperatively.

Aged↗
PubMed2003

[Endoscopic thoracic surgery: indications, feasibility, and limitations].

Mediastinoscopy and mediastinotomy are used primarily in the staging of lung cancer; they are also of value in biopsying mediastinal masses and lymph nodes to establish diagnoses such as sarcoidosis,lymphoma, and mediastinal tumors. Video-assisted thoracic surgery (VATS) was introduced in 1990 and has now replaced open thoracotomy in the evaluation of many pleuropulmonary disorders. Specific advantages of VATS over open thoracotomy include the use of smaller incisions, reduced operative morbidity, and optimal visualization of the entire lung and pleural space. In many centers it has become the procedure of choice for the biopsy of interstitial disease, indeterminate lung nodules, or pleural lesions. The role of VATS for staging of lung cancer patients is still under debate. VATS procedures have also been adopted for the treatment of a wide range of thoracic disorders. With increasing experience surgeons have become more skilled with this limited access technique and meanwhile lobectomies can be performed safely. The role of VATS in the management of lung metastases or lung cancer is still being investigated. It is a concern that there is a temptation to do less when a minimal access operation is performed that does not allow for palpation of the lung. In addition, lymph node dissection cannot be performed adequately and there continue to be reports of local recurrences in port sites. If the VATS approach is to be used, surgeons should always respect the oncological principles that have been developed over the past decades.

Biopsy↗
PubMed2003

Non-small-cell superior sulcus tumor: results of en bloc resection in fifty-six patients - non-small-cell pancoast.

BACKGROUND: Various multidisciplinary approaches are taken in the treatment of superior sulcus tumors. The purpose of this study was to determine the outcome, long-term results, and factors associated with prolonged survival after administering different combined radiosurgical regimens in a single institution. METHODS: Between 1986 and 2000, 56 patients (43 men, 13 women) with superior sulcus tumor and histology of non-small-cell lung cancer underwent surgical resection. There were four treatment groups: I - preoperative radiation and operation (n = 15); II - preoperative radiation, operation and postoperative radiation (n = 22); III - operation and postoperative radiation (n = 10) and IV - no radiotherapy (n = 9). Survival was calculated by the Kaplan-Meier method and prognostic factors were assessed for significance by log-rank test and Cox regression analysis. RESULTS: The five-year survival rate after complete resection and N0/1 was 34 %. Of the prognostic factors analyzed, the histology, type of irradiation regimen and Horner's syndrome did not influence survival. Completeness of resection and mediastinal lymph node involvement clearly influences survival in univariate analysis. Age, sex and TNM classification were found to be independent significant prognostic factors for survival following resection. CONCLUSION: With superior sulcus tumors, every attempt should be made to resect the tumor completely by en bloc chest-wall resection with lobectomy and systematic hilar and mediastinal lymph node dissection. Mediastinal exploration by routine mediastinoscopy is recommended for identification of patients with advanced nodal involvement. Long-term survival may be relative to care taken in patient selection and extent of the resection performed. No significant difference in survival of patients with different irradiation regimens could be demonstrated in this study.

Aged↗
PubMed2003

Design and application of a new cell for in situ infrared reflection-absorption spectroscopy investigations of metal-atmosphere interfaces.

A new experimental setup for studying reactions occurring in the metal-atmosphere interface by applying in situ infrared reflection-absorption spectroscopy (IRRAS) is presented. It consists of a gas-mixing unit, where the moist air is generated with or without corrosive gases, the reaction cell for the in situ investigations, and an optical system coupled with a Fourier transform infrared (FT-IR) spectrometer. For testing the unit, a specimen of pure copper was used, where the growth of Cu2O on the polished surface could be observed during time-resolved measurements in synthetic air containing 80% RH (relative humidity). For comparison of the experimental results obtained, a computer simulation program was developed in order to calculate the peak position, the peak height, the peak width, and the thickness of the surface layer formed during the atmospheric corrosion. The simulation software is based on the four-phase model of covered surfaces.

Atmosphere↗
PubMed2002

Adsorption study of cationic dyes having a trimethylammonium anchor group on hectorite using electrooptic and spectroscopic methods.

Clay minerals are natural or synthetic material of colloidal dimensions. Due to the sheetlike structure clay minerals offer a huge specific surface area and hence optimal properties for modification through adsorption. The current work studies the adsorption of five cationic dyes on the synthetic clay mineral hectorite. All dyes have a trimethylammonium anchoring group in common. The adsorbed dye molecules are characterized by means of pulsed electric linear dichroism and UV-VIS spectroscopy. With increasing dye loading a continuous shift in the absorption spectra is observed. But there is no occurrence of a new absorption band. Therefore we conclude that the dyes preferentially adsorb as amorphous aggregates on the clay surface. At low dye loadings the dye molecules lie flat on the clay mineral surface. Increasing dye concentration leads to a continuous increase in average tilt angle. However the orientation of the dye molecules is very sensitive to functional groups. The introduction of a nitro group to a particular dye increases significantly the tendency to lie flat on the surface whereas the introduction of a methoxy group at the same position has the opposite effect.

Journal Article↗
PubMed2002

[Endobronchial ultrasound for local tumour and lymph node staging in patients with centrally growing lung cancer].

AIM: Lung cancer is a common disease and exact staging is of extreme importance in order to plan therapy. A frequent problem in assessing the extent of tumour spread is the question of infiltration versus compression of central airways by central tumours and a correct lymph node staging. Chest CT as the general imaging procedure of choice is often not helpful with these questions. Endobronchial ultrasound (EBUS) has been available for several years, and we were interested to find out if the addition of EBUS to regular bronchoscopy can help to differentiate between airway infiltration and external compression and improves the yield of transbronchial needle aspiration (TBNA). METHOD: Patients with central tumour growth and enlarged lymph nodes were examined with EBUS and CT, classified according to local tumour invasion, and a needle biopsy of the lymph nodes was performed after EBUS detection. RESULTS: 50 patients were examined and subsequently operated. Relative to the local T-staging EBUS resulted in a sensitivity of 89 % and a specificity of 100 %. The results were highly improved statistically compared to the CT results (sensitivity 25 %, specificity 80 %). With EBUS-guided TBNA the results of correct N-staging could be improved to 86 %. CONCLUSION: Our study suggests that EBUS, if performed by experienced endoscopists for the detection of airway wall infiltration or compression is highly accurate and superior to chest CT in assessing potential airway infiltration by a malignant tumour. Furthermore, the results of the lymph node staging could be improved through the additional use of EBUS. It is easily performed within the context of a standard bronchoscopy and may spare many patients unnecessary surgical biopsies.

Biopsy, Needle↗
PubMed2001

[Tracheobronchial injuries and fistulas].

In association with perforating or blunt trauma, isolated injuries of the trachea and the bronchi are rarely seen. More frequently, however, they occur when adjacent organs or structures are involved, thus creating very complex syndromes. Symptoms such as dyspnea, coughing attacks, hemoptysis, soft tissue emphysema, cyanosis, and pneumothorax should point to severe tracheobronchial injuries. Diagnosis is confirmed through an emergency tracheobronchoscopy; early surgical repair is mandatory. Iatrogenic injuries--most often due to intubation maneuvers--are infrequent but potentially life-threatening and demanding immediate repair except in cases with superficial tears. Leading symptoms of transmural lacerations are dyspnea, soft tissue emphysema, and pneumothorax. Tracheoesophageal fistulas result from decubital necrosis caused by long-term intubation. With spontaneous healing never occurring, surgical repair is carried out ideally by closing both openings in chronic fistulas, while simultaneous tracheal stenosis is treated by segmental resection. Tracheoarterial fistulas, mostly associated with tracheostomy, become fatal if not detected immediately. Definitive repair requires the resection of the vascular segment involved.

Aged↗
PubMed2001

Invasive staging of lung cancer by mediastinoscopy and video-assisted thoracoscopy.

Accurate evaluation of the outcomes of clinical trials using preoperative chemotherapy in a multimodality treatment protocol may require invasive pretreatment staging for pathologic confirmation of the clinical TNM. Mediastinoscopy and videothoracoscopy complement each other to provide appropriate staging of lung cancer. Invasive staging utilizing both methods may accurately determine the presence or absence of N2 and N3 disease, and identify T3 or T4 or thoracic M1 disease.

False Negative Reactions↗
PubMed2001

A role for complement C5 in organism containment and granulomatous response during murine tuberculosis.

The molecular mechanisms underlying protective granuloma formation and control of bacterial growth during infection with Mycobacterium tuberculosis (MTB) are not yet completely understood. MTB-infected mice with natural deficiency in complement component C5 are unable to develop productive granulomatous responses, and are impaired in limiting organism growth within the lung. To address the molecular basis for this histologic dysfunction, congenic complement C5-sufficient (B10.D2-H2d H2-T18c Hcl/nSnJ) and complement C5-deficient strains (B10.D2-H2d H2-T18c Hco/oSnJ) congenic mice were infected with Mycobacterium tuberculosis, and cytokine and chemokine responses were examined. Twelve and 28 days after infection, lungs showed elevated messages for multiple inflammatory cytokines in both congenic strains. Interleukin (IL)-12(p40) mRNA was also induced during infection in C5-deficient mice, although levels were significantly decreased compared to C5-sufficient congenics. C5-deficient mice also demonstrated reduced KC, MIP-2, IP-10, and MCP-1 mRNA. The defect may directly involve C5-mediated effects on macrophage responses; C5-deficient bone marrow derived macrophages had significantly reduced secretion of KC, MIP-1 alpha and MIP-2 compared to C5-sufficient macrophages following in vitro infection. These findings indicate a role for C5 in mediation of chemotactic and activation events that are the basis for granulomatous responses during murine tuberculosis.

Animals↗
PubMed2001

Distribution of the outer membrane haem receptor protein ChuA in environmental and human isolates of Escherichia coli.

ChuA, the haem receptor of Escherichia coli, is thought to contribute to the pathogenicity of E. coli strains causing extraintestinal infections. We investigated the prevalence and distribution of chuA in E. coli analysing 304 strains from different origins. 30% of E. coli strains isolated from the environment and about 70% of E. coli strains isolated from human sources carried chuA. No difference in chuA prevalence was found between commensals isolated from the intestine of healthy volunteers and isolates from extraintestinal infections. Our results indicate that ChuA might be involved in the colonization of human hosts.

Bacterial Outer Membrane Proteins↗
PubMed2001

Pleural posttransplantation lymphoproliferative disorder following liver transplantation.

A case of posttransplantation lymphoproliferative disorder (PTLD) involving the pleura is reported. The patient was a 57-year-old man who underwent liver transplantation 2 years prior to the development of PTLD. The PTLD was pleural-based and was first detected by radiologic studies as a pleural effusion. Transbronchial biopsy and cytologic examination of 2 pleural fluid specimens were nondiagnostic. Subsequent open-wedge biopsy revealed a monomorphic PTLD, composed of large immunoblasts with plasmacytoid differentiation. Immunohistochemical studies demonstrated B-cell lineage with expression of monotypic cytoplasmic immunoglobulin kappa light chain and CD79a, and absence of T-cell antigens. Immunohistochemical and in situ hybridization studies demonstrated Epstein-Barr virus protein and RNA, respectively. No evidence of human herpesvirus 8 DNA was detected by polymerase chain reaction. We report this case because pleural-based PTLD is rare. The diagnosis of this entity is made more difficult by the fact that PTLD is often underrepresented in pleural fluid cytology samples.

Epstein-Barr Virus Infections↗
PubMed2000

Lesion-induced changes in NMDA receptor subunit mRNA expression in rat visual cortex.

Focal lesions in the visual cortex are well known to induce pronounced perilesional reorganization of the neuronal circuitry. Since NMDA receptors crucially control synaptic plasticity and reorganization, we studied lesion-induced changes in their subunit expression and biophysical properties. Between 8 and 10 days after focal thermolesioning, pyramidal neurones in the near surround of the lesion were studied in acute brain slices. We found a significant decrease in the ratio of NR2A and NR2B subunit mRNA as compared to neurones from sham operated animals. Interestingly, no significant differences in the properties of NMDA receptor-mediated postsynaptic currents (NMDA PSCs) were observed between lesioned and sham operated animals. Thus, the observed perilesional changes in the NR2A/NR2B mRNA ratio appear to be subthreshold to result in significant changes in the functional properties of NMDA receptors.

Animals↗
PubMed2000

Expression screening of factors binding to the osteocalcin bone-specific promoter element OC box I: isolation of a novel osteoblast differentiation-specific factor.

Contributing to bone-specific expression of the osteocalcin gene is the promoter element OC Box I (-99 to -76), which binds both Hox proteins and another nonhomeodomain factor (designated OCBP for osteocalcin-box binding protein) (Hoffmann et al. [1996] J Cell Biochem 61:310-324). OCBP correlates with increased promoter activity and may, therefore, be important to development or maintenance of the osteoblast phenotype. To identify OCBP candidates, we used a multimerized OC Box I sequence to screen a gammagt11 cDNA expression library, constructed from the rat osteosarcoma osteoblastic ROS 17/2.8 cell line, for cDNA clones encoding factors that recognize this element. Mutant OC Box I sequences that do not bind OCBP and/or homeodomain proteins were used to counterscreen the cDNA isolates. Clones showing binding specificity were sequenced and further characterized for patterns of expression in different tissues and cell lines. Among the characterized nonhomeodomain-related isolates, we identified a nucleolin, a clone encoding rCAP2 that is related to myogenic differentiation and more importantly, a cDNA clone containing a previously uncharacterized gene that has been designated as a cell differentiation-related factor (DRF). DRF mRNA is highly expressed in ROS 17/2.8 cells and in a developmentally regulated pattern during osteoblast differentiation, being upregulated at the postproliferative maturation transition and coinciding with the induction of osteocalcin gene expression. The 7.7-kb transcript encoded by clone 44 is abundantly expressed in osteoblasts, but the mRNA was not present at detectable levels in bone and soft tissues by Northern blot analysis. However, related expressed sequence tags were recently reported in cDNA libraries of rat lung and mouse sympathetic ganglion. The identification of DRF represents a novel osteoblast differentiation-specific marker related to osteocalcin expression. The identification of DRF may further facilitate definition of gene regulatory mechanisms mediating the final stages of bone cell differentiation

Animals↗
PubMed2000

Hopelessness and its impact on rehabilitation outcome in schizophrenia -an exploratory study.

The primary focus in contemporary psychiatry on symptoms and their neurobiological basis, although fundamentally important, is nevertheless incomplete. The long-term course and outcome of schizophrenia are determined not only by the disorder, but also by the interaction between the person and the disorder. Not only psychopathological symptoms but also cognitive variables such as negative self-concepts, low expectations and external loci of control can influence the patient's coping strategies and may lead to hopelessness and chronicity. Hopelessness here refers to a cognitive-affective state in which the patient perceives the disorder and its consequences to be beyond his control, feels helpless and has given up expecting to influence its course positively, thereby abandoning responsibility and active coping strategies. In a prospective study, we examined these relationships by using logistic regression in data from 46 schizophrenic outpatients who were participating in a vocational rehabilitation program. Negative self-concepts, external loci of control, and depression correlated to a higher extent with depressive-resigned coping strategies than did schizophrenic symptoms. Thus, poor rehabilitation outcome may be predicted to a high degree by the presence of external loci of control, pessimistic outcome expectancies, negative symptoms, and depressive-resigned coping strategies. After having eliminated the influence of negative symptoms, external control beliefs still had significant predictive value for the outcome. Rehabilitation outcome in schizophrenic patients can be only partially predicted by negative symptoms; the other predictive factor is whether the patient has already given up or not.

Adaptation, Psychological↗