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Biomedical subjects

B Lauer

Publications and source records attributed to B Lauer.

At least 19 recordsLinked to original sources

[Stable tachycardia with wide QRS complex in pre-hospital emergency medicine].

BACKGROUND: Sustained, stable wide QRS-complex tachycardia (WCT) remains a diagnostic challenge, because the treatment of supra-ventricular tachycardia (SVT) with aberrant conduction differs considerably from that of a ventricular tachycardia (VT). A usual recommendation for treating a case of a stable WCT is to manage it as if it were VT, in accordance with the consideration of "first do no harm". The aim of this study was to determine whether Board-certified emergency-physicians are able to differentiate VT from SVT with aberrant conduction in a high percentage of cases (> 90%), thus to assure more precise prehospital treatment." METHODS: Eight electrocardiograms with WCT (four with electrophysiologically proven VT or SVT, respectively) were evaluated in a blinded fashion by 64 Board-certified emergency-physicians (23 female, 41 male, mean age: 37,8 + 5,1 years). Initially, the diagnosis had to be made without any further information. Afterwards the same electrocardiograms were presented again, providing important additional information. RESULTS: 55% of the study population were able to establish the correct diagnosis merely by evaluating the electrocardiogram. Providing the above mentioned additional information, the number of correct diagnoses increased to 61%. These results were roughly similar in all subgroups, only the subgroup of cardiologists showed a trend to better results with correct diagnoses in 68% without and 73 % with additional information. None of the subgroups reached the pre-specified cut-off of > or = 90% correct diagnoses. Specialist status as well as experience in emergency medicine had no significant influence on the results, only the subgroup of emergency physicians with an experience of more than five years showed a trend towards a higher rate of correct diagnosis, compared with the subgroup with less than one year experience in emergency medicine. CONCLUSION: In cases of stable WCT the evaluation of the electrocardiogram without further information in prehospital emergency-medicine leads to unsatisfactory results. The correct diagnosis in WCT can be improved by using additional data but the diagnostic accuracy is still low. Therefore, the differential diagnosis of stable WCT in preclinical emergency-medicine cannot be recommended. Until proven otherwise, any stable WCT should be managed as if it were VT.

Adult↗

[First diagnosis of Fallot tetralogy in a 74-year-old man].

Tetralogy of Fallot is the most common cyanotic cardiac malformation in late childhood and adult, occurring in approximately 0.25 of 1000 live births. Most patients undergo early surgical correction. Therefore, the natural history of this disease has been evaluated in only a few cases. We report a complex case of a tetralogy of Fallot, who reached the age of 74 years without surgical or medical treatment and who was transferred to our clinic after syncope due to ventricular tachycardia.

Aged↗

Allele-specific quantification of HLA-DQB1 gene expression by real-time reverse transcriptase-polymerase chain reaction.

In addition to coding region polymorphism, allele-specific variation in the upstream regulatory region of the HLA-DQB1 gene has been detected. Reporter gene assays and transfection studies have indicated that HLA-DQB1 promoter polymorphism may be of functional significance. The aim of this study was to utilize real-time reverse transcriptase-polymerase chain reaction (RT-PCR) for allele-specific quantification of HLA-DQB1 expression and to analyze cell-specific HLA-DQB1 expression in vivo. For the allele-specific quantification of DQB1 gene products, a real-time RT-PCR set of primer pairs (n=27) and probes (n=5) targeting exon 2 variability was established. The robustness and integrity of the assay system were confirmed by using recombinant DQB1 exon 2 plasmid clones as active exogenous controls. Sensitivity and reproducibility were assessed by serial dilution and allelic mixing analyses. In application to the study of allele-specific expression of DQB1 gene products during cytokine-driven maturation of monocyte-derived dendritic cells, differential patterns of allelic expression in heterozygous individuals were observed for DQB1*0301, compared to DQB1*0501 and DQB1*0602. At maximum, 1.9-fold (*0301/*0501) and 2.5-fold (*0301/*0602) higher induction was seen for DQB*0301. In conclusion, HLA-DQB1 expression can be analyzed by real-time RT-PCR suitable for cell- and allele-specific detection of HLA-DQB1 transcripts in homo- and heterozygous combinations.

Alleles↗

Alterations of myocardial presynaptic sympathetic innervation in patients with multi-vessel coronary artery disease but without history of myocardial infarction.

In patients with myocardial infarction, left ventricular sympathetic denervation exceeds the size of the scar tissue. However, little is known about the regional innervation in patients with coronary artery disease (CAD) but no myocardial infarction. Using positron emission tomography (PET) with N-ammonia and C-hydroxyephedrine (HED), resting perfusion and presynaptic sympathetic innervation were studied in eight patients (seven males, one female; 58+/-9 years) with multi-vessel CAD and no history of myocardial infarction. Using polar map analysis of the PET data, the results were regionally compared with normal databases. The mean HED retention was 8.0%+/-2.0% x min(-1). Myocardial resting perfusion was normal in 23 of 24 vascular territories. Despite normal resting perfusion, significantly reduced HED retention, indicating dysinnervation, was found in 14 of 23 (61%) vascular territories (six of eight patients). Of the dysinnervated territories, 11 (79%) showed angiographically severe stenosis (>or=90% of native vessel/coronary artery bypass graft), eight (57%) showed ischaemia (myocardial perfusion scintigraphy/stress-electrocardiogram) and 12 (86%) had been revascularized. Of the nine segments with normal innervation, two (22%) revealed severe stenosis, two (22%) showed ischaemia and seven (78%) had been revascularized. It can be concluded that, in patients with advanced CAD and normal left ventricular function, dysinnervation can occur in the absence of myocardial infarction. This is consistent with the hypothesis that sympathetic neurones are more susceptible than myocytes to ischaemic damage.

Aged↗

Reversal of cardiogenic shock by percutaneous left atrial-to-femoral arterial bypass assistance.

BACKGROUND: Recovery of myocardial function after revascularization of acutely occluded coronary arteries may require several days. During this critical time, patients in cardiogenic shock may have low output. A newly developed percutaneous left ventricular assist device (VAD) may offer effective treatment for these patients by providing active circulatory support. METHODS AND RESULTS: Between May 2000 and May 2001, VADs were implanted in 18 consecutive patients who had cardiogenic shock after myocardial infarction. The device was connected to the patient's circulation by insertion of a 21F venous cannula into the left atrium by transseptal puncture; blood was returned to the iliac artery through an arterial cannula. Mean duration of cardiac assistance was 4+/-3 days. Mean flow of the VAD was 3.2+/-0.6 L/min. Before support, cardiac index was 1.7+/-0.3 L/min per m(2) and improved to 2.4+/-0.6 L/min per m(2) (P<0.001). Mean blood pressure increased from 63+/-8 mm Hg to 80+/-9 mm Hg (P<0.001). Pulmonary capillary wedge pressure, central venous pressure, and pulmonary artery pressure were reduced from 21+/-4, 13+/-4, and 31+/-8 mm Hg to 14+/-4, 9+/-3, and 23+/-6 mm Hg (all P<0.001), respectively. Overall 30-day mortality rate was 44%. CONCLUSIONS: A newly developed VAD can be rapidly deployed in the catheterization laboratory setting. This device provides up to 4.0 L/min of assisted cardiac output, which may aid to revert cardiogenic shock. The left ventricle is unloaded by diverting blood from the left atrium to the systemic circulation, making recovery more likely after an ischemic event. The influence of this device on long-term prognosis warrants further investigation.

Adult↗

Molecular characterization of co-transcribed genes from Streptomyces tendae Tü901 involved in the biosynthesis of the peptidyl moiety and assembly of the peptidyl nucleoside antibiotic nikkomycin.

Six genes (nikP1, nikP2, nikS, nikT, nikU, and nikV) from Streptomyces tendae Tu901 were identified by analysis of the nucleotide sequence of the nikkomycin gene cluster. These genes, together with the previously described nikQ and nikR, span 9.39 kb and are transcribed as a polycistronic mRNA in a growth-phase-dependent manner. The nikP1 gene encodes a non-ribosomal peptide synthase consisting of an adenylation domain, a thiolation domain, and an N-terminal 70-residue segment of unknown function. The amino acid sequence encoded by the nikP2 gene displays similarity to the sequences of thioesterases, and the nikS product belongs to a superfamily of proteins characterized by a specific ATP-binding fold. The N-terminal 70 amino acids of the predicted nikT gene product show significant sequence similarity to acyl carrier proteins, and the C-terminal 330 amino acids to aminotransferases. The sequences of the deduced proteins NikU and NikV exhibit similarity to components S and E, respectively, of glutamate mutase from Clostridium. Disruption of the nikP1, nikS, nikT, or nikV gene by insertion of a kanamycin resistance cassette abolished formation of nikkomycins I, J, X, and Z, all of which contain hydroxypyridylhomothreonine as the peptidyl moiety. The nikP1 mutants, and the nikS and nikT mutants accumulated the nucleoside moieties nikkomycin Cz, and nikkomycins Cx and Cz, respectively. The nikV mutants formed nikkomycins Ox and Oz, which contain 2-amino-4-hydroxy-4-(3'-hydroxy-6'-pyridyl) butanoic acid as the peptidyl moiety. The nikP2 mutants synthesized nikkomycins I, J, X, and Z, but amounts of nikkomycins I and X, which contain formylimidazolone as the base, were lower. Feeding formylimidazolone to nikP2 mutants restored the ability to form nikkomycins I and X. Our results indicate that nikU and nikV are required for the synthesis of hydroxypyridylhomothreonine, the genes nikP1, nikP2 and nikS are required for the assembly of nikkomycins, and nikT is required for both pathways. The putative activities of each of their products are discussed.

Amino Acid Sequence↗

No more tours: how library tours of the past become today's celebrations.

In 1999, Northwestern University's Galter Health Sciences Library redesigned the library orientation program for first-year medical students. Surveys indicated tours were ineffective and students retained little of the information presented. Furthermore, the tour was not related to the student's curriculum and did not reinforce their learning objectives. As a replacement, the library staff developed a self-directed two-hour library open house. Stations throughout the library showcased the library staff, services, and resources, focusing on the first-year student curriculum. A follow-up survey found this redesign more useful and relevant to the students' course work, indicating libraries should be creating more interactive tours for students allowing them to learn actively.

Chicago↗

Diagnostic value of intraoperative swabs of heart valves in infective endocarditis.

BACKGROUND AND AIM OF THE STUDY: Intraoperative swabs of heart valves are obtained regularly from patients undergoing heart valve surgery for infective endocarditis (IE) in order to confirm the preoperative diagnosis and to adjust the antibiotic regimen. The study aim was to assess the diagnostic value of intraoperative swabs of heart valves in IE. METHODS: A total of 83 patients was referred for surgical treatment of active IE between October 1994 and May 1999. Preoperatively, microorganisms were isolated using a minimum of two positive blood cultures; results were compared with those obtained from intraoperative heart valve swab cultures. RESULTS: Preoperatively, 73 patients (88%) had a positive blood culture, and 10 (12%) had culture-negative endocarditis. The intraoperative swab confirmed the preoperative diagnosis in 31 cases (37%). Bacteria were isolated in three of the ten patients with preoperative culture-negative IE. Despite positive histopathological findings in seven patients, no microorganisms were cultured either pre- or intraoperatively. Among the remaining 42 patients (51%) with active IE, 25 valve cultures were sterile and 17 valve swabs were presumed to be contaminated. CONCLUSION: In patients with active IE in whom the causative agent could be isolated and identified before surgery, intraoperative valve swabs did not contribute further to patient management. In isolating contaminants, the risk of inappropriate modification of the antibiotic regimen is imminent. The diagnostic validity in culture-negative IE appears negligible.

Adolescent↗

[Percutaneous myocardial laser revascularization. A new therapy technique for patients with coronary disease and severe angina pectoris without conventional therapy options].

BACKGROUND AND OBJECTIVES: In patients with intractable angina because of end-stage coronary artery disease, transmyocardial laser revascularization (TMR) leads to improvement of angina pectoris and increased exercise capacity. However, surgical thoracotomy is required for TMR with considerable morbidity and mortality. Therefore, a catheter-based laser system has been developed which allows to create laser channels into the myocardium from the left ventricular cavity. PATIENTS AND METHODS: 46 patients (38 m, 8 f) with refractory angina pectoris due to severe coronary artery disease were treated with "percutaneous myocardial laser revascularisation" (PMR). Clinical parameters (severity of angina pectoris, use of additional nitroglycerin) and results of non-invasive tests (exercise-ECG, echocardiography, thallium-scintigraphy) were analysed at baseline and 3, 6 and 12 months after PMR. RESULTS: The PMR procedure was successfully completed in all patients. In 30 patients, one region (anterior, lateral, inferior) of the left ventricle was treated and in 16 patients, 2 or 3 regions were treated. Clinical follow-up demonstrated significant improvement of angina pectoris (CCS-class at baseline: 3.1 +/- 0.2, 3 months after PMR: 1.8 +/- 0.7, 12 months after PMR: 1.5 +/- 0.9) (p < 0.001) and increased exercise capacity (exercise time on standard bicycle ergometry at baseline: 383 +/- 151 s, 3 months after PMR: 494 +/- 140 s, 12 months after PMR: 480 +/- 151 s) (p < 0.05), but thallium scintigraphy failed to show improved perfusion of the laser treated regions. CONCLUSIONS: PMR is a new safe and feasible therapeutic option in patients with refractory angina pectoris due to end-stage coronary artery disease. Initial results show significant improvement of clinical symptoms and an increased exercise capacity but thallium scintigraphy failed to show improved perfusion after PMR.

Aged↗

[Percutaneous myocardial laser revascularization (PMR)].

In patients with severe angina pectoris due to coronary artery disease, who are not candidates for either percutaneous coronary angioplasty or coronary artery bypass surgery, transmyocardial laser revascularization (TMR) often leads to improvement of clinical symptoms and increased exercise capacity. One drawback of TMR is the need for surgical thoracotomy in order to gain access to the epicardial surface of the heart. Therefore, a catheter-based system has been developed, which allows creation of laser channels into the myocardium from the left ventricular cavity. Between January 1997 and November 1999, this "percutaneous myocardial laser revascularization" (PMR) has been performed in 101 patients at the Herzzentrum Leipzig. In 63 patients, only 1 region of the heart (anterior, lateral, inferior or septal) was treated with PMR, in 38 patients 2 or 3 regions were treated in 1 session. There were 12.3 +/- 4.5 (range 4 to 22) channels/region created into the myocardium. After 3 months, the majority of patients reported significant improvement of clinical symptoms (CCS class at baseline: 3.3 +/- 0.4, after 6 months: 1.6 +/- 0.8) (p < 0.001) and an increased exercise capacity (baseline: 397 +/- 125 s, after 6 months: 540 +/- 190 s) (p < 0.05). After 2 years, the majority of patients had experienced sustained clinical benefit after PMR, the CCS class after 2 years was 1.3 +/- 0.7, exercise capacity was 500 +/- 193 s. However, thallium scintigraphy failed to show increased perfusion in the PMR treated regions. The pathophysiologic mechanisms of myocardial laser revascularization is not yet understood. Most of the laser channels are found occluded after various time intervals after intervention. Other possible mechanisms include myocardial denervation or angioneogenesis after laser revascularization, however, unequivocal evidence for these theories is not yet available. In conclusion, PMR seems to be a safe and feasible new therapeutic option for patients with refractory angina pectoris due to end-stage coronary artery disease. The first results indicate improvement of clinical symptoms and increased exercise capacity, whereas evidence of increased perfusion after laser revascularization in the laser-treated regions is still lacking.

Adult↗

Changes in myocardial perfusion after catheter-based percutaneous laser revascularisation.

This study investigated the effect of percutaneous laser revascularisation (PMR) on regional myocardial blood flow. PMR is a new therapeutic modality for patients suffering from angina pectoris due to coronary artery disease (CAD) that is not amenable to revascularisation. Initial clinical studies discovered reduced angina pectoris and increased exercise capacity after PMR. There are no previous clinical studies reporting the impact of PMR on perfusion. Thirty-six patients with end-stage CAD underwent thallium-201 single-photon emission tomography studies on four different occasions: immediately before PMR and 3, 6 and 12 months following PMR. Each study consisted of pharmacological stress and rest scintigraphy. Semiquantitative evaluation was performed by use of 14 standardised wall segments which were classified (a) according to the localisation of the PMR target region into treated segments, segments adjacent to the treated area and non-treated segments and (b) according to the pre-therapeutic local perfusion into four groups: no (0), slight (I), moderate (II) or severe (III) perfusion deficit. At stress in treated segments of groups II and III local scintigraphic count densities increased from 60.1% and 34.7% at baseline to 65.3% and 48.3% after 12 months (P<0.05) while they decreased in segments of group 0 from 94.2% to 85.7% (P<0.05). In rest studies no changes occurred. Thus, the local rest-stress differences within the target areas become smaller after PMR. In the PMR target area but not in the nontreated area an improvement in regional myocardial flow reserve occurs in wall segments with initially severely or moderately reduced stress perfusion. This effect is consistent with the clinical improvement after PMR.

Aged↗

[Intravenous long-term thrombolysis of an occluded aortocoronary venous bypass graft].

A 41-year-old man presented with progressive unstable angina pectoris during the last three hours. At admission the electrocardiogram and cardiac specific enzymes showed no signs of ischemia. During the next 24 hours the electrocardiogram and cardiac enzymes developed signs of a non-Q-wave anterolateral infarction. The patient had known coronary artery disease and underwent aortocoronary bypass surgery seven years ago. Coronary angiography after admission revealed a chronically occluded vein graft to the right coronary artery (RCA) and a subtotal occlusion of the vein graft to the left anterior descending artery (LAD) with a TIMI flow 0-I. Because of unfavorable results of mechanical revascularization of occluded bypass grafts and high risk of catheter dislocation and bleeding complications of intracoronary local thrombolysis, the patient subsequently received intravenous long-term thrombolysis for 24 hours. After successful lysis of the thrombus the bypass graft to the LAD showed two severe stenoses but blood flow has returned to normal. Three days later percutaneous transluminal coronary angioplasty (PTCA) and stent implantation were carried out with a good primary angiographic result. After 6 months the patient was still asymptomatic and a treadmill exercise test showed no signs of ischemia.

Adult↗

[Myocardial laser revascularization in therapy-refractory angina pectoris].

In patients with coronary artery disease and intractable angina, who are not candidates for either coronary artery bypass grafting (CABG) or percutaneous transluminal coronary angioplasty (PTCA), transmyocardial laser revascularization (TMR) has been developed as a new treatment. Several recently published, randomized trials have consistently shown improvement of clinical symptoms and increased exercise capacity after TMR compared to medical therapy. However, surgical thoracotomy is required for TMR with considerable morbidity and mortality. Therefore, catheter-based systems have been developed, which allow creation of laser channels in the myocardium from within the left ventricular cavity. These systems for "percutaneous myocardial revascularization" (PMR) use laser energy generated by Holmium: YAG lasers, which can be transmitted to the myocardium via flexible optical fibers. PMR leads to significant improvement of clinical symptoms and increased exercise capacity similar to TMR. The CCS classification is improved about 1.5 classes, independent of the PMR system used. However, evidence of improved perfusion after PMR is still lacking. The pathophysiologic mechanisms of myocardial laser revascularization are still poorly understood. Experimental studies indicate myocardial neoangiogenesis and myocardial denervation after TMR; however, clinical studies have not yet found evidence of improved myocardial perfusion after myocardial laser revascularization.

Angina Pectoris↗

[Late diagnosis of Curschmann-Steinert myotonic dystrophy in a female patient with dilated cardiomyopathy and in her son].

A 41 year old woman presented with dyspnoea at rest and swollen legs in the emergency room of our centre. She reported a history of slowly progressing dyspnoea and oedema in the legs. Physical examination showed signs of biventricular congestive heart failure and dysmorphia of the face. Routine laboratory examination revealed elevated CK levels without significant elevations of the CK-MB isoform. ECG showed complete left bundle branch block and first degree atrioventricular block. Echocardiography and angiography showed markedly reduced left ventricular systolic function, the ejection fraction was 25%. Coronary angiography excluded CAD and there was no evidence for congenital or valvular heart disease. The patient also reported a history of a serious complication during emergency general anaesthesia and cataracts of both eyes. Because of the clinical and chemical findings, the history of cataracts and complications during general anaesthesia, a systemic congenital disease of the muscular tissue was suspected. Molecular studies revealed a trinucleotide amplification at the myotonic dystrophy locus 19q 13.3, so the diagnosis myotonic dystrophy Curschmann-Steinert was established. The sixteen year old son of the patient suffered from an at this time unknown disease with retardation, muscular weakness and myotonia of the face. The diagnosis myotonic dystrophy was evident because of the clinical signs and the family history.

Adolescent↗