Biomedical subjects
Publications and source records attributed to R Busch.
Accessory molecules, such as HLA-DM and invariant chain, modulate the ligands bound to MHC class II molecules in antigen-presenting cells. Recent investigations, including gene targeting experiments, have shed light on the functions of these molecules, their mechanisms of action, interactions with class II molecules, and the relationships with associated molecules such as tetraspanins and HLA-DO.
HLA-DM removes CLIP and other loosely bound peptides from MHC class II molecules. The crystal structures of class II molecules and of HLA-DM have not permitted identification of their interaction sites. Here, we describe mutations in class II that impair interactions with DM. Libraries of randomly mutagenized DR3 alpha and beta chains were screened for their ability to cause cell surface accumulation of CLIP/DR3 complexes in EBV-B cells. Seven mutations were associated with impaired peptide loading in vivo, as detected by SDS stability assays. In vitro, these mutant DR3 molecules were resistant to DM-catalyzed CLIP release and showed reduced binding to DM. All mutations localize to a single lateral face of HLA-DR, which we propose interacts with DM during peptide exchange.
The detection of epithelial cells in bone marrow, blood or lymph nodes indicates a disseminatory potential of solid tumours. 225 patients with squamous cell carcinoma of the oesophagus were prospectively studied. Prior to any therapy, cytokeratin-positive (CK) cells in bone marrow were immunocytochemically detected in 75 patients with the monoclonal anti-epithelial-cell antibody A45-B/B3 and correlated with established histopathologic and patient-specific prognosis factors. The prognosis factors were assessed by multivariate analysis. Twenty-nine of 75 (38.7%) patients with oesophageal cancer showed CK-positive cells in bone marrow. The analyses of the mean and median overall survival time showed a significant difference between patients with and without epithelial cells in bone marrow (P < 0.001). Multivariate analysis in the total patient population and in patients with curative resection of the primary tumour confirmed the curative resection rate and the bone marrow status as the strongest independent prognostic factors, besides the T-category. The detection of epithelial cells in bone marrow of oesophageal cancer patients is a substantial prognostic factor proved by multivariate analysis and is helpful for exact preoperative staging, as well as monitoring of neoadjuvant therapy.
OBJECTIVE: To compare prognostic results in patients with gastric stump cancer (GSC) versus those with primary gastric cancer (PGC). SUMMARY BACKGROUND DATA: Gastric stump carcinomas have often been described as having low resectability rates and a poor prognosis. METHODS: Results of surgical treatment of 50 patients with GSC were compared with that of 516 patients with PGC. RESULTS: The resectability rate was 94% for GSC patients and 96.5% for PGC patients, without significant differences in terms of postoperative complications, death rate, and median survival time (31.6 vs. 32.9 months). The multivariate analysis showed an independent prognostic effect for R0 resection, pT1 and pT2 category, and age older than 65 years. CONCLUSION: The prognosis after resection and adequate lymphadenectomy does not differ between patients with GSC and PGC.
BACKGROUND: Factors possibly predicting airway invasion of oesophageal cancer in the absence of frank oesophagotracheal fistulas have not been studied. OBJECTIVES: To identify possible predictors of airway invasion by oesophageal cancer that are readily accessible in the preoperative setting. METHODS: We prospectively investigated 148 patients with newly diagnosed oesophageal cancer located at or above the level of the tracheal bifurcation and without any evidence of oesophago-respiratory fistulas or distant metastases. Demographic variables, respiratory parameters, results of bronchoscopy and other staging procedures (oesophagoscopy, swallow oesophagography, endosonography, CT and histology) and findings at surgery were compared between the patients with (n = 30) and without (n = 118) proven airway invasion and entered into a stepwise logistic regression model to evaluate their independent predictive roles. RESULTS: Univariate analysis indicated that the incidence of airway invasion increased with the presence of suspect CT findings, the presence of respiratory symptoms, tumour length, T stage on endoscopic ultrasonography, and histopathologic grading of the primary cancer. A multivariate logistic regression model indicated that suspect CT findings (odds ratio, 4.4; 95% confidence interval 1.7-11.1, p = 0.002) and maximal tumour length >8 cm (odds ratio, 3.7; 95% confidence interval 1.4-9.6, p = 0.007) were associated independently with airway invasion. The accuracy of predicting airway invasion was 82.5% with both variables combined. CONCLUSIONS: The high incidence of airway involvement by oesophageal cancer and the difficulty to predict it accurately with clinical data or other staging procedures justifies the routine use of bronchoscopy in all patients with the tumour located at or above the level of the tracheal bifurcation. A particular effort to objectively prove or exclude airway invasion should be made in patients with tumours longer than 8 cm and/or with CT findings suggesting airway invasion.
Allograft rejection and its differentiation from other causes of organ dysfunction remains a diagnostic problem in liver transplant patients. Currently, acute rejection can be prevented only by a combination of diagnostic and therapeutic modalities. The diagnostic potential of a novel implantable telemetric rejection monitoring device has been assessed on the basis of the noninvasive impedance analysis in normal and liver transplanted pigs. The electric impedance data were correlated with biochemical and histological parameters. Acute rejection was correctly predicted in n = 4, and correctly excluded in n = 32, biopsy-related impedance recordings (p = 0.004). A correlation between impedance measurements and severity of histological findings r = 0.84; p = 0.0001) was confirmed. Only the biochemical parameters SGLDH and serum bilirubin revealed a comparable correlation. Impedance gradient analysis revealed evidence of a physiological relationship between liver function and the electrical properties of the organ. Telemetric impedance analysis would appear a promising means of assessing acute rejection noninvasively.
BACKGROUND: Despite ongoing controversy, hyperbaric oxygen (HBO) therapy is frequently administered in various clinical situations. Probably because of the unique atmospheric conditions to which the patient is exposed, there are concerns about the safety aspects of this therapy. Possible complications during HBO therapy include barotraumatic lesions (middle ear, nasal sinuses, inner ear, lung, teeth), oxygen toxicity (central nervous system, lung), confinement anxiety, and ocular effects (myopia, cataract growth). METHODS: To analyze the medical safety of HBO therapy, this report reviewed complications and side effects of 782 patients treated for various indications with a total of 11,376 HBO therapy sessions within a multiplace chamber. The absolute treatment pressure was 240 or 250 kPa 114 or 15 msw). The compression was performed in a linear manner with 14 to 15 kPa (1.4 to 1.5 msw) x min(-1). All data were gathered prospectively within a special database. RESULTS: More than 17% of all patients experienced ear pain or discomfort as an expression of problems in equalizing the middle ear pressure. Most episodes were not related to a persistent eustachian tube dysfunction since they only occurred once. Barotraumatic lesions on visual otological examinations (ear microscopy) were verified in 3.8% of all patients. Patients with sensory deficits involving the ear region need special attention, because they seem to be at risk for rupture of the tympanic membrane (three cases documented). A barotrauma of the nasal sinuses occurred rarely and no barotraumatic lesions of the inner ear, lung, or teeth were noted. Oxygen toxicity of the CNS manifested by generalized seizures affected four patients without any recognizable risk factors or prodromes. None of the patients suffered recurrences or sequelae. Regular checks of the blood glucose in diabetics failed to reveal episodes of hypoglycemia as a cause for seizures. Lung function tests of patients undergoing prolonged treatment (average 52.8 sessions) did not deteriorate. CONCLUSION: Patients scheduled for HBO therapy need a careful pre-examination and monitoring. If safety guidelines are strictly followed, HBO therapy is a modality with an acceptable rate of complications. The predominant complication is represented by pressure equalization problems within the middle ear. Serious complications rarely occur.
A primary goal of the histopathologic evaluation of the gastric resection specimen is the determination of prognostically relevant factors, but it is not known whether, following neoadjuvant therapy, these factors have the same influence on prognosis. The goal of this study was to investigate prognostically relevant macroscopic and microscopic findings after neoadjuvant chemotherapy. The resection specimens of 36 patients with locally advanced gastric carcinoma who had been treated with Etoposide, Adriamycin and Cisplatin were investigated with respect to tumor size, Lauren type, ypTNM, UICC R-status, lymphangiosis, and degree of regression. On the basis of these factors, a prognosis score was developed that included both the degree of regression (grade 1-3), staging parameters (UICC T-category, R-status), tumor size and lymphatic vessel invasion. All of the parameters were weighted according to a score (1 point--best, 3 points--worst). The points were added for each individual case and the cases were divided into three prognosis groups, Group A: 5-7 points (n = 5), Group B: 8-10 points (n = 15), and Group C: > or = 11 points (n = 16). When compared with survival by the Kaplan-Meier method, these three prognosis groups showed highly significant differences (p < 0.0001). These results demonstrate that it is possible to accurately predict survival using resection specimens following neoadjuvant chemotherapy, which could lead to the identification of subgroups for which additional, further adjuvant therapy might be useful.
Chronic lymphocytic leukemia (CLL) shows a remarkably heterogeneous clinical outcome; survival ranges from several months in advanced stages to more than 10 years in early stages. The Binet and Rai staging systems distinguish three major prognostic subgroups, but do not accurately predict the individual risk of disease progression in early CLL (Binet stage A or Rai stage 0 to II). Because most newly diagnosed CLL patients present with early disease, it seems desirable to search for additional prognostic factors to identify early CLL patients at high risk of rapid progression. It has been shown that elevated serum thymidine kinase (s-TK) levels predict disease progression in CLL. Therefore, this study aimed to assess the prognostic value of s-TK in 122 previously untreated patients with Binet stage A CLL (mean age +/- SD, 58.7 +/- 8.5 years). In univariate analyses, 18 of the 22 parameters investigated predicted progression-free survival (PFS). In a stepwise multiple regression analysis, only three parameters provided independent prognostic information on PFS: s-TK greater than 7.1 U/L; presence of lymphadenopathy; and white blood cell (WBC) count greater than 75, 000/microL. When added to the classification of smoldering versus nonsmoldering CLL, s-TK levels separated two groups within the group of nonsmoldering stage A patients: patients with s-TK values greater than 7.1 U/L had a median PFS of 8 months, whereas patients with s-TK values </= 7.1 U/L expected a much longer PFS (49 months; P <. 001), similar to smoldering CLL (42 months). The results demonstrate that s-TK is a prognostic parameter that adds independent prognostic information to the definitions of smoldering and nonsmoldering CLL in Binet stage A.
In patients with cleft lip and palate (CLP), the assessment of velopharyngeal morphology and function and the quantitative analysis of perceptual consequences of velopharyngeal insufficiency are of major importance regarding the effective planning of velopharyngoplasties for speech improvement. The NasalView, a new instrument for the objective assessment of rhinophonia, is presented. The NasalView measures nasalance, the relative sound pressure level of the nasal signal in speech, expressed as a percentage. In order to evaluate the effectiveness of the computerised measurement of nasalance, 156 patients with surgically treated CLP were examined. The NasalView differentiated with high sensitivity and specificity between patients with normal nasal resonance and patients with varying degrees of hypernasality. To illustrate the importance of the NasalView for making the decision for a velopharyngoplasty, a single case is presented.
OBJECTIVE: To compare morbidity and mortality rates of stented versus nonstented pancreaticojejunostomy after partial pancreatoduodenectomy. BACKGROUND DATA: Despite a marked reduction in the mortality rate after partial pancreatoduodenectomy in recent years, leakage of the pancreaticojejunostomy still occurs in 5% to 25% of patients and remains the major source of complications. METHODS: The authors compared the morbidity and mortality rates of 85 consecutive patients who had a partial pancreatoduodenectomy with (n = 44) or without (n = 41) temporary stented external drainage of the pancreatic duct between 1994 and 1997. RESULTS: A pancreatic fistula was diagnosed in 3 of the 44 patients (6.8%) with stents versus 12 of the 41 patients (29.3%) without stents. Surgical reintervention was necessary in 1 of the 3 patients with a pancreatic fistula in the stented group and 3 of the 12 patients with a pancreatic fistula in the nonstented group. There were two deaths after surgery, both in the nonstented group. The median hospital stay after surgery was 13 days in patients with stents and 29 days in patients without stents. CONCLUSION: In this nonrandomized prospective observational study, temporary external drainage of the pancreatic duct with a PVC tube significantly reduced the leakage rate of the pancreaticojejunostomy as well as the duration of hospital stay after partial pancreatoduodenectomy. Although promising, these observations require confirmation by further studies.
Infolge eines primären Defizits der velopharyngealen Funktion liegen bei vielen Patienten mit Lippen-Kiefer-Gaumenspalten sekundäre kompensatorische Lautbildungen vor. Mit zwei neuen Computerprogrammen werden die Auswirkungen der kompensatorischen Artikulation auf die durchschnittliche Sprechgeschwindigkeit von 146 Patienten mit Lippen-Kiefer-Gaumen-spalten untersucht. Die Patienten wurden dabei nach dem Schweregrad der artikulatorischen Auffälligkeit gruppiert. Bei der schnellen Silbenwiederholung zeigte sich, dass die durchschnittliche Silbenrate pro Sekunde bei Patienten mit deutlich auffälliger Artikulation signifikant reduziert war. Beim Nachsprechen von Sätzen war die zum Nachsprechen benötigte Gesamtzeit bei dieser Patientengruppe signifikant erhöht, und das Zielwort des Satzes wurde signifikant später begonnen. Die Ergebnisse zeigen, dass die mittlere Sprechgeschwindigkeit von Patienten mit Lippen-Kiefer-Gaumenspalten mit kompensatorischer palatolalischer Artikulation niedriger ist.
HLA-DM catalyzes the release of invariant chain fragments from newly synthesized major histocompatibility complex (MHC) class II molecules, stabilizes empty class II molecules, and edits class II-associated peptides by preferentially releasing those that are loosely bound. The ability of HLA-DM to carry out these functions in vitro is pH dependent, with an optimum at pH 4.5-5.5 and poor activity at pH 7. The structural basis for these properties of HLA-DM is unknown. Sequence homology suggests that HLA-DM resembles classical, peptide-binding MHC class II molecules. In this study, we examined whether HLA-DM has a secondary structure composition consistent with an MHC fold and whether HLA-DM changes conformation between pH 5 and pH 7. Far-UV circular dichroism (CD) spectra of recombinant soluble HLA-DM (sDM) indicate that HLA-DM belongs to the alpha/beta class of proteins and structurally resembles both MHC class I and class II molecules. The CD peak around 198 nm increases upon going from neutral to endosomal pH and drops sharply upon denaturation below pH 3.5, distinguishing at least three states of sDM: the denatured state and two highly similar folded states. Fluorescence emission spectra show a slight blue-shift and a approximately 20% drop in intensity at pH 5 compared with pH 7. Unfolding experiments using guanidinium chloride show that the stability of sDM is somewhat reduced but not lost at pH 5. These results indicate that sDM undergoes a pH-dependent conformational change between neutral and endosomal pH. The change seems to involve both hydrogen bonding patterns and the hydrophobic core of sDM and may contribute to the pH dependence of DM activity.
The HLA-DR hemizygous B lymphoblastoid cell line, 10.24.6, has a DRA mutation (Pro96-->Ser) that creates a novel glycosylation site at Asn94. The mutant DR molecules are primarily associated with nested fragments of invariant chain (class II-associated invariant chain peptides), and their interaction with HLA-DM is impaired. Here we further analyzed the defect in 10.24.6 cells. Expressing Ser96 mutant DRA cDNA in DRA-null cells recapitulated the 10.24.6 phenotype, indicating that the mutation causes the Ag presentation defect. A mutation to Ala96alpha, which does not introduce an extra glycan, generated a normal phenotype; the critical role of the glycan was further supported by experiments in which N-glycosylation was blocked by tunicamycin. We also evaluated whether the 10.24.6 mutation affected DR3 maturation or trafficking. Metabolic labeling and subcellular fractionation showed that assembly, endosomal transport, and invariant chain proteolysis of mutant DR3 molecules were similar to wild-type. A slight delay in export from the endoplasmic reticulum to the Golgi apparatus in 10.24.6 cells probably did not contribute significantly to the Ag presentation defect, because the abundance of DM and mutant DR in peptide-loading compartments was normal at steady state. Our results indicate that proper localization of these molecules does not depend on their interaction.
BACKGROUND: Classification of lymph node metastasis from gastric carcinoma was based on the localization (International Union Against Cancer/American Joint Committee on Cancer [UICC/AJCC] 1992). The authors analyzed the data of the German Gastric Cancer Study (GGCS) to determine whether the number of involved lymph nodes related to the prognosis independent of their anatomic localization (UICC/AJCC 1997). METHODS: For 477 patients of the GGCS resected for cure (UICC/AJCC R0 resection) who had involved regional lymph nodes and no evidence of distant metastases, the 1992 UICC/AJCC classification was compared with the new UICC/AJCC classification (1997) based on the number of involved lymph nodes (ILN). RESULTS: Two hundred fifty-eight patients (54.1%) had 1-6 ILN, 137 patients (28.7%) had 7-15, and 82 patients (17.2%) had more than 15. When the 1992 and 1997 UICC/AJCC classifications were compared, the prognosis of patients classified as pN1 (n = 187) in the 1992 pN classification was homogeneous, whereas there was a marked lack of homogeneity among the patients classified as pN2 (n = 290). For 103 of 290 patients with 1-6 ILN, the prognosis appeared to be more favorable (5-year survival rate, 45.5%), whereas 137 of 290 patients with 7-15 ILN had an intermediate prognosis (5-year survival rate, 29.7%). Eighty-two of 290 patients had a dismal prognosis, with a 5-year survival rate of 10.4%. There was a highly significant difference in survival (P < 0.0001). Within the groups with 1-6, 7-15, and more than 15 ILN, the localization of ILN did not significantly alter the prognosis. CONCLUSIONS: The UICC/AJCC classification based on the number of involved regional lymph nodes allows for an estimation of prognosis superior to the 1992 classification. In addition, the new classification can now be applied without methodologic problems and seems more reproducible.
HLA-DM (abbreviated DM) is an MHC-encoded glycoprotein that catalyzes the selective release of peptides, including class II-associated invariant chain peptides, from MHC class II molecules. To perform its function, DM must assemble in the endoplasmic reticulum (ER), travel to endosomes, and interact productively with class II molecules. We have described previously an EBV-transformed B cell line, 7.12.6, which displays a partial Ag presentation defect and expresses a mutated DM beta-chain with Cys79 replaced by Tyr. In this study, we show that HLA-DR molecules in 7.12.6 have a defect in peptide loading and accumulate class II-associated invariant chain peptides (CLIP). Peptide loading is restored by transfection of wild-type DMB. The mutant DM molecules exit the ER slowly and are degraded rapidly, resulting in greatly reduced levels of mutant DM in post-Golgi compartments. Whereas wild-type DM forms noncovalent alphabeta dimers, such dimers form inefficiently in 7.12.6; many mutant DM beta-chains instead form a disulfide-bonded dimer with DM alpha. Homodimers of DM beta are also detected in 7.12.6 and in the alpha-chain defective mutant, 2.2.93. We conclude that during folding of wild-type DM, the native conformation is stabilized by a conserved disulfide bond involving Cys79beta and by noncovalent contacts with DM alpha. Without these interactions, DM beta can form malfolded structures containing interchain disulfide bonds; malfolding is correlated with ER retention and accelerated degradation.
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.
We compared the parental age at birth of patients with Alzheimer disease (AD) with that of cognitively healthy control subjects. Within 206 carefully diagnosed AD patients, two groups were distinguished according to the likelihood of carrying a major gene for AD (MGAD). This likelihood was calculated by applying a Bayesian approach which incorporates data on aggregation of the disease, age at onset, and "censoring" ages within the family. All AD patients were ranked by MGAD probability. According to the sample's quartiles, two subgroups were defined representing the 52 individuals with the lowest and the 52 with the highest MGAD probability. Age at onset of dementia, education, and apolipoprotein E epsilon4 allele frequencies were not statistically different between the two groups. Fathers of patients with a low MGAD probability were significantly older (35.7+/-8.1 years) than fathers of both other groups (high MGAD probability 31.3+/-6.9 years, P=0.004; controls 32.6+/-6.8 years, P=0.04, n=50). The differences for mothers were less pronounced and not statistically significant. These findings suggest that increased paternal age is a risk factor for AD in the absence of a major gene, whereas increased maternal age and AD are associated only weakly and independently of genetic disposition.