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Biomedical subjects

M Langer

Publications and source records attributed to M Langer.

At least 19 recordsLinked to original sources
PubMed1997

Treatment of ostial renal-artery stenoses with vascular endoprostheses after unsuccessful balloon angioplasty.

BACKGROUND: Percutaneous transluminal renal angioplasty is a safe and effective treatment for nonostial stenoses of the renal arteries, but it has proved to be disappointing for ostial stenoses. Therefore, we prospectively studied the use of intravascular stents for the treatment of critical ostial stenoses after unsuccessful balloon angioplasty. METHODS: Stainless-steel endoprostheses were placed across 74 renal-artery stenoses located within 5 mm of the aortic lumen in 68 patients with hypertension. Twenty patients had mild or severe renal dysfunction. The indications for stent placement were elastic recoil (63 arteries) or dissection (1 artery) of the vessel after angioplasty, or restenosis after initially successful balloon angioplasty (10 arteries). Patients were followed for a mean of 27 months with measurements of blood pressure and serum creatinine, duplex sonography, and intraarterial angiography. RESULTS: Initial technical success was achieved in all patients. Minor complications (local hematomas) occurred in only three patients; there were no major complications. Eighty-four percent of the patients were free of primary occlusion 60 months after the procedure. Restenosis of more than 50 percent of the vessel diameter occurred in 8 of 74 arteries (11 percent). Reintervention resulted in a secondary patency rate of 92 percent. Long-term normalization of blood pressure was achieved in 11 patients (16 percent). Serum creatinine levels did not change significantly after successful stent implantation in patients with previously impaired renal function. CONCLUSIONS: Accurate placement of renal-artery stents is technically feasible without major complications. The favorable early and long-term results suggest that primary stent placement is an effective treatment for renal-artery stenosis involving the ostium.

Adult↗
PubMed1996

A nonradioactive assay for ribosome-inactivating proteins.

A sensitive nonradioactive method to determine the activity of ribosome-inactivating proteins (RIPs) based on a combined transcription/translation in vitro assay was established. Using this assay we investigated the RIP activities of the heterodimeric toxic plant lectins ricin and mistletoe lectin I (ML-I). The enzymatic activities of the holoproteins were compared to that of the RIP-active chain of ML-I (ML-I A-chain) and recombinant ML-I A-chain expressed in Escherichia coli. The IC50 values determined for the plant toxins showed that the translation-inactivating activity of ML-I (39.8 pM) is about four times higher than that of ricin (176.0 pM). The plant-derived ML-I A-chain is more toxic (3.4 pM) in the cell-free translation system than the respective holoprotein. The recombinant ML-I A-chain was found to be about three times less active (IC50 10.6 pM) than the A-chain from plant. The in vitro assay described here is a convenient method for the fast determination of RIP activity with a 1000-fold lower detection limit than that of commonly used RIP assays.

Animals↗
PubMed1996

[Reflux esophagitis--diagnosis and differential diagnosis].

The combination of the two typical symptoms - heartburn and regurgitation - is almost proving gastrooesophageal reflux disease (GORD). Further - atypical - symptoms are dysphagia, odynophagia, pharyngitis, reflux-induced pulmonary symptoms or intermittent chest-pain. Endoscopic signs of GORD are patchy reddening of the mucosa, erosions, ulcers and stricture. Barretts oesophagus is characterized by columnar epithelial metaplasia. Consequence: Typical symptoms of GORD may be treated without further diagnostic procedure whereas in the case of atypical symptoms diagnosis of GORD has to be established by endoscopy.

Barrett Esophagus↗
PubMed1996

[Hemosuccus pancreaticus--a rare cause of upper gastrointestinal bleeding. Successful treatment in two cases by radiologic-interventional embolization of the splenic artery].

HISTORY AND CLINICAL FINDINGS: Two patients were admitted to hospital for diagnosis of recurrent upper gastrointestinal bleeding. Both had chronic pancreatitis with alcohol abuse. Their general condition was satisfactory. Physical examination showed no diagnostic abnormalities other than mild epigastric pain on pressure in one patient. INVESTIGATIONS: In case 1 angiography revealed pseudoaneurysm of the splenic artery as a complication of chronic pancreatitis to be the cause of the bleeding. In case 2 sonography demonstrated multiple pancreatic pseudocysts after recurrent pancreatitis. Duplex sonography revealed one of the cyst to be a partly thrombosed pseudoaneurysm of the splenic artery and the source of the bleeding. TREATMENT AND COURSE: In both cases a fistula between splenic artery and pancreatic duct having been shown to be the source of the bleeding, transcatheter embolisation of the splenic artery with platinum coils was successfully undertaken. Both patients remained symptom-free 4 and 10 months later. CONCLUSION: Although haemosuccus pancreaticus is a rare cause of upper gastrointestinal bleeding, given certain features in the patient's history and the clinical findings, it should be included in the differential diagnosis.

Aneurysm, False↗
PubMed1996

Patterns of disease failure after trimodality therapy of nonsmall cell lung carcinoma pathologic stage IIIA (N2). Analysis of Cancer and Leukemia Group B Protocol 8935.

BACKGROUND: The impact of sequential trimodality therapy on the pattern of first site disease failure in pathologic Stage IIIA (N2) nonsmall cell lung carcinoma (NSCLC) was analyzed. METHODS: Seventy-four eligible patients with histologically documented Stage IIIA (N2) NSCLC underwent sequential trimodality therapy on Cancer and Leukemia Group B (CALGB) Protocol 8935. Treatment consisted of 2 cycles of induction cisplatin at 100 mg/m2 intravenously (i.v.) (Days 1 and 29) and vinblastine at 5 mg/m2 i.v. weekly for 5 weeks followed by surgery. Surgery included a thoracotomy with resection of the primary tumor and hilar lymph nodes and a mediastinal lymph node dissection. Patients with resected disease then received an additional a cycles of cisplatin at 100 mg/m2 i.v. and vinblastine at 5 mg/m2 i.v. biweekly for 2 total of 4 doses followed by consolidative thoracic irradiation. Patients with completely resected disease received 54 Gray (Gy) whereas those with incompletely resected disease received 59.4 Gy at 1.8 Gy/fraction (fx) once a day. Patients with unresectable disease underwent thoracic radiation therapy (TRT) treatments only to 59.4 Gy at 1.8 Gy/fx without any additional chemotherapy. Disease recurrence was determined by clinical, radiographic, or histologic criteria. Pattern of disease failure was identified by site of involvement at first recurrence as indicated by the CALGB Respiratory Follow-Up Form. RESULTS: Sixty-three of the 74 patients completed the induction chemotherapy as planned. Forty-six of the 63 patients underwent resection of disease whereas the remaining 17 were unresectable. Thirty-three of the 46 resected patients completed the entire adjuvant postoperative chemoradiation treatment as planned. Ten of 17 patients with unresectable disease completed postsurgical TRT. At a median follow-up interval of 27 months (range, 4-43), the 3-year overall survival and failure-free survival were 23% and 18%, respectively, for all 74 eligible patients. Overall, disease failure has occurred in 52 (70%) of the 74 eligible patients: local only: 13 (25%); distant only: 16 (31%); and both local and distant: 23 (44%), (P = not significant [NS]). Ten patients progressed during induction chemotherapy: local only: six patients; and both local and distant failure: four patients. Twenty-eight of 46 resected patients recurred: local only: 1 (4%); both local and distant failure: 11 (39%); and distant only: 16 (57%); (P < 0.001). Disease progression occurred in 14 of 17 patients with unresectable disease: local only: 6; both local and distant sites: 8. Among the 52 total patients experiencing disease relapse, isolated or combined local failure occurred commonly among patients during induction chemotherapy (n = 10, [28%]), in those with unresectable disease (n = 14, [39%]), or in those with resected disease (n = 12, [33%]), (P = NS). However, isolated or combined distant failure was more likely to occur among patients with resected disease (n = 27, [69%]) than either during induction chemotherapy (n = 4, [10%]) or in those with unresected disease (n = 8, [21%]), (P < 0.05). Among patients who relapsed, brain metastases occurred in 13 of 52 (25%) patients overall and in 12 of 28 (43%) patients with resected disease. CONCLUSIONS: Overall, disease failure was just as likely to occur in local, distant, or combined sites on CALGB Protocol 8935 using sequential trimodality therapy in the treatment of pathologic Stage IIIA (N2) NSCLC: Isolated or combined local failure occurred commonly during sequential tri-modality therapy whereas isolated or combined distant relapse was prevalent among patients with resected disease. In addition, isolated local failure was rare among patients with resected disease. The pattern of disease failure on CALGB Protocol 8935 reflects the biology of locoregional NSCLC as much as the therapeutic impact of trimodality therapy.

Adenocarcinoma↗
PubMed1996

Central pontine myelinolysis: clinical presentation and radiologic findings.

Central pontine myelinolysis (CPM) is a neurologic disorder once thought to be uniformly fatal. With the introduction of CT and MRI there was an increasing number of reports on nonfatal cases of CPM. Nearly all reports on nonfatal cases describe severe clinical syndromes with tetraparesis, bulbar palsy, and coma. We reviewed nine patients with CPM and compared the size of the pontine lesion on MRI and CT with the severity of clinical presentation. Clinical presentation of CPM was highly variable: The symptoms ranged from severe neurologic disorders to mild neurologic disturbances only. Two of nine patients died from CPM. The size of the pontine lesion did not correlate with the severity of the neurologic illness or the final outcome. Mild forms of CPM might be difficult to diagnose clinically. This applies even more for patients with underlying diseases such as Wernicke's encephalopathy, which in itself might cause a clinical picture similar to that of CPM. Central Pontine Myelinolysis is a major differential diagnosis in acute neurologic deterioration indicating pontine damage. Magnetic resonance imaging is the decisive diagnostic tool for CPM.

Adult↗
PubMed1996

Short-term impact of the European Consensus Conference on the use of selective decontamination of the digestive tract with antibiotics in ICU patients.

Because it remained controversial, the use of selective digestive decontamination (SDD) in patients in the intensive care unit (ICU) was chosen as the topic of the first European Consensus Conference in Intensive Care Medicine (ECCICM) in December, 1991. The Consensus Bureau decided to assess the impact of this conference 2 years afterwards. For this purpose, a questionnaire was sent to the members of the European Society of Intensive Care Medicine, the Societé de Réanimation de Langue Française and the Societé Française d'Anesthesie et Réanimation before the conference. The recommendations following the conference discouraged the systematic use of SDD in ventilated patients and urged the monitoring of bacterial resistance and adapting antibiotics to epidemiology of the units. Two years after the conference, the same questionnaire was sent to those physicians who had responded to the first one. Eighteen percent used SDD for all ventilated patients and 17% remain users after 2 years. Among the occasional (32%) or continual (17%) users of SDD, the regimens used were mostly intravenous cefotaxime (60% of systemic antibiotics) and a topical combination of polymixin E, tobramycin, and amphotericin B (62% of overall topical combinations). The antibiotics used were unchanged after 2 years in almost all cases. In conclusion, the short-term impact of the Consensus Conference on SDD in ICU patients has been poor. This may be related to the continuing insufficiency of strong, definite data regarding the impact of this technique upon mortality and the theoretical risk of resistance to antibiotics, thus allowing physicians to stick to their policies until there is new evidence.

Anti-Bacterial Agents↗
PubMed1996

[Morphology of the carpal tunnel. Movement studies in patients with constriction symptoms and healthy probands using MR tomography].

The morphological correlation of the phenomenon of increased pressure in the carpal tunnel during wrist flexion and extension--as has been proved though measurements using wick-catheters--was studied in healthy subjects (n = 15) and symptomatic patients with carpal tunnel syndrome (n = 15). Our own measurements using magnetic resonance imaging (MRI) showed that there is a significant reproducible decrease in carpal tunnel diameter when the wrist is held in position of either flexion or extension. During flexion the diameter is decreased at the pisiformes and hamate level as well as it is lowered during extension at the pisiformes level. This might explain the rise in carpal tunnel pressure and thus the consecutive negative influence on the median nerve. Proximal swelling, distal flattening and increased signal intensity of the median nerve as well as the palmar bulging of the flexor retinaculum at the level of the hook of the hamate and at the level of the pisiformes were significantly higher in patients with carpal tunnel syndrome than in normal volunteers (from p < 0.05 to p < 0.001). In post-operative follow-up examinations of 13 patients with no clinic symptoms the distal flattening of the median nerve normalized in 94% within 3 months. The increased signal of the median nerve on T2-weighted images decreased postoperatively in 2/3 of the patients, whereas the motor latency of the median nerve recovered only in 39% of our patients who had 100% partial or complete clinical benefit. These findings imply that postoperative imaging may be helpful for evaluating the success or failure of surgical treatment.

Adult↗
PubMed1996

Metabolic response to radiation therapy in patients with cancer.

The effect of radiation therapy on substrate metabolism was evaluated in five patients with head and neck or lung cancer. Stable isotope tracer methodology was used to determine urea, amino acid, glucose, and lipid kinetics during postabsorptive conditions before initiation, near the midpoint (after receiving 2,672 +/- 36 rads), and at completion (after receiving 6,072 +/- 307 rad) of a 6- to 8-week course of radiation therapy. Nutritional status was maintained throughout the treatment period by providing supplemental enteral feedings as needed. Postabsorptive plasma insulin, catecholamine, and amino acid concentrations did not change during the course of treatment. Before radiation therapy was initiated, values for the plasma rate of appearance (Ra) of urea (3.35 +/- 0.33 micromol x kg(-1) x min(-1)), alpha-ketoisocaproate ([alpha-KIC] 2.16 +/- 0.19 micromol x kg(-1) x min(-1)), phenylalanine (0.59 +/- 0.052 micromol x kg(-1) x min(-1)), and glucose (10.56 +/- 1.31 micromol x kg(-1) x min(-1)) were in the normal range. However, glycerol and palmitate Ra values (3.11 +/- 0.30 and 2.01 +/- 0.33 micromol x kg(-1) x min(-1), respectively) were 25% higher than values observed previously in normal subjects. Substrate flux did not change during radiation therapy, and measurements obtained during the midpoint and at completion of treatment were similar to initial values. These results demonstrate that large doses of radiation therapy, administered over 6 to 8 weeks to the upper body, do not cause significant metabolic stress.

Amino Acids↗
PubMed1996

[Ultrasound and mammography follow-up of findings after breast saving operation and adjuvant irradiation].

AIM: The aim of our controlled retrospective study was to assess the diagnostic value of sonography for detection and characterisation of changes compared to mammography and palpation. METHOD: In 80 patients sonographic and clinical follow-up examinations were performed every 3 to 6 months, mammography examinations were performed every 6 to 12 months during the first 2 years after breast-preserving therapy (BPT) and irradiation. Extension, echogenicity, and configuration of lesions in sonography, and semiquantitiative description of diffuse or circumscribed changes in mammography were the basis of comparative follow-up observation. RESULTS: Postoperative seromas and haematomas, initially presenting echo-free or as hypoechoic lesions, showed an increase in echogenicity within 18 months after irradiation. Fat necrosis occurred in 9.5% of patients, lymph cysts developed in 4%, granuloma in 3%, recurrence of neoplasma in 1.6%. The diffuse loss of transparency in mammography that was associated with radiation therapy, showed a peak 6-12 months after irradiation. CONCLUSION: Sonography and sonographic guided puncture are mandatory tools to characterise circumscribed unclear lesions after breast-conserving therapy and irradiation in specialised centers. We recommend a 6-month interval for combined sonography, palpation, and mammography within the first 2 years after BPT and irradiation, because shorter control intervals did not result in relevant diagnostic advantages.

Adult↗
PubMed1996

[Endoluminal therapy of infrarenal abdominal aortic aneurysms: a new interventional technique].

PURPOSE: With a series of 31 transluminal stent-graft procedures, we assessed the feasibility and clinical effectiveness of a new stent-graft for the treatment of infrarenal abdominal aortic aneurysms (AAAs). METHODS: We treated the patients (male; mean age 71 years) with straight or bifurcated nitinol stents covered with woven dacron graft material for infrarenal eccentric saccular AAA (n = 4) or AAA involving the bifurcation and the common iliac arteries (n = 27). The 18-F delivery system was advanced via a surgical arteriotomy and the stent-graft was placed under fluoroscopic control. Follow-up period ranged from 8 days to 9 months. RESULTS: The implantation of the stent-grafts was technically successful in 30/31 cases. Procedure-related complications were acute hepatic failure due to gastric bleeding in a patient with liver cirrhosis, graft occlusion due to emboli originating from the left atrium (n = 1), macro-embolisation (n = 3), local haematoma (n = 1) and av-fistula (n = 1) requiring surgery. A post-implantation syndrome with leukocytosis and elevated C-reactive protein was observed in all patients. CONCLUSIONS: Endoluminal repair of infrarenal AAA with use of dacron covered nitinol stent-grafts is feasible, safe and clinically effective. However, careful long-term evaluation is necessary.

Aged↗
PubMed1996

Efficacy of intraoperative heat administration by ventilation with warm humidified gases and an oesophageal warming system.

We measured changes in body temperature in 12 hypothermic (mean aural temperature 34.4 (SD 1.0) degrees C) pigs during general anaesthesia with an open abdominal cavity and the effect of two warming systems: heating of inspired gases to 39 degrees C (intratracheal temperature) and oesophageal warming to 39 degrees C by a water perfused oesophageal heat exchanger. Each animal underwent both treatments and the control period in random sequence. Each condition was studied over 1 h. No additional protection against heat loss (drapes, blankets, i.v. fluids warming, etc.) was used. Anaesthesia, room temperature and relative humidity, amount and temperature of infusions and extension of exposed visceral surfaces were standardized. Mean decrease in body temperature was 1.0 (0.7) degree C (P < 0.005) without warming and 0.6 (0.2) degree C (P < 0.005) with heated inspired gases: this difference was not statistically significant. Oesophageal warming was very efficient as mean body temperature did not change significantly (-0.1 (0.2) degree C; ns).

Anesthesia, General↗
PubMed1996

A comparison of mixed integer programming and fast simulated annealing for optimizing beam weights in radiation therapy.

Two competing methods for assigning intensities to radiation treatment beams were tested. One method was derived from mixed integer programming and the other was based on simulated annealing. The methods faced a common objective and identical constraints. The goal was to maximize the minimum tumor dose while keeping the dose in required fractions of normal organ volumes below a threshold for damage. The minimum tumor doses of the two methods were compared when all the dose-volume constraints were satisfied. A mixed integer linear program gave a minimum tumor dose that was at least 1.8 Gy higher than that given by simulated annealing in 7 of 19 trials. The difference was > or = 5.4 Gy in 4 of 19 trials. In no case was the mixed integer solution one fraction size (1.8 Gy) worse than that of simulated annealing. The better solution provided by the mixed integer program allows tumor dose to increase without violating the dose-volume limits of normal tissues.

Abdominal Neoplasms↗
PubMed1996

A generic genetic algorithm for generating beam weights.

A genetic algorithm for generating beam weights is described. The algorithm improves an objective measure of the dose distribution while respecting dose volume constraints placed on critical structures. The algorithm was used to select beam weights for treatment of abdominal tumors. Weights were selected for up to 36 beams. Dose volume limits were placed on normal organs and a dose inhomogeneity limit was placed on tumor. Volumes were represented as sets of several hundred discrete points. The algorithm searched for the beam weights that would make the minimum tumor dose as high as the constraints would allow. The results were checked using dose volume histograms with standard sized grids. Nineteen trials were created using six patient cases by changing the required field margin or allowed beam position in each case. The sampling of points was sufficiently dense to yield solutions that strictly satisfied the constraints when the prescribed dose was renormalized by a factor of less than 6%. The genetic algorithm supplied solutions in 49 min on average, and in a maximum time of 87 min. The randomized search does not guarantee optimality, but high tumor doses were obtained. An example is shown for which the solution of the genetic algorithm gave a minimum tumor dose 7 Gy higher than the solution given by a simulated annealing algorithm under the same set of constraints. The genetic algorithm can be generalized to admit nonlinear functions of the beam intensities in the objective or in the constraints. These can include tumor control and normal tissue complication probabilities. The genetic algorithm is an attractive procedure for assigning beam weights in multifield plans. It improves the dose distribution while respecting specified rules for tissue tolerance.

Abdominal Neoplasms↗
PubMed1996

Abdominal aortic aneurysms: preliminary technical and clinical results with transfemoral placement of endovascular self-expanding stent-grafts.

PURPOSE: To evaluate treatment of infrarenal abdominal aortic aneurysm (AAA) with a new endoluminal stent-graft. MATERIALS AND METHODS: In 26 male patients, straight or bifurcated nitinol stents covered with woven Dacron graft material were implanted to treat eccentric saccular AAA (n = 3) or AAA involving the bifurcation and common iliac arteries (n = 23), with follow-up from 8 days to 8 1/2 months. RESULTS: Implantation was technically successful in all but one of the 26 (96%) patients (leak of the stent-graft for more than 3 months necessitated implantation of an additional covered stent). In seven of the 26 patients, minor residual perfusion persisted immediately after implantation, but complete thrombosis occurred within 7 days. Five procedure-related complications occurred: distal embolization (n = 2); local hematoma, which necessitated surgery (n = 1); acute hepatic failure due to gastric bleeding, in a patient with liver cirrhosis (n = 1); and stent-graft occlusion due to emboli originating from the left atrium (n = 1). CONCLUSION: Exclusion of AAA from circulation was feasible, safe, and clinically effective with the new stent-graft.

Aged↗