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Biomedical subjects

M Heinemann

Publications and source records attributed to M Heinemann.

At least 19 recordsLinked to original sources
PubMed2003

The Fontan-operation: from intra- to extracardiac procedure.

PURPOSE: For treatment of univentricular heart, the Fontan operation has been established as the definitive palliation. The current controversy is mainly based on the high incidence of arrhythmias after an intra-atrial lateral tunnel Fontan operation. METHODS: From January 1995 until April 2002, 46 children underwent a Fontan-type operation with or without a small fenestration. In 33 patients (group I) an intracardiac tunnel and in 13 patients (group II) an extracardiac conduit procedure was performed. PRINCIPAL FINDINGS: There was no perioperative mortality. All patients showed postoperative a significant increase of arterial oxygen saturation, from 76 to 86% after surgery with fenestration, or to 90.5% without fenestration respectively. In patients with fenestration procedure, the saturation rose to 90% after closure of fenestrations 9 to 12 months after operation. CONCLUSIONS: Modified Fontan operations can be performed in normothermia on the beating heart with acceptable mortality. The extracardiac conduit Fontan procedure has the benefits of less surgical injury and a higher intraoperative flexibility.

Adolescent↗
PubMed2003

Experimental studies of applications of time-reversal acoustics to noncoherent underwater communications.

The most difficult problem in shallow underwater acoustic communications is considered to be the time-varying multipath propagation because it impacts negatively on data rates. At high data rates the intersymbol interference requires adaptive algorithms on the receiver side that lead to computationally intensive and complex signal processing. A novel technique called time-reversal acoustics (TRA) can environmentally adapt the acoustic propagation effects of a complex medium in order to focus energy at a particular target range and depth. Using TRA, the multipath structure is reduced because all the propagation paths add coherently at the intended target location. This property of time-reversal acoustics suggests a potential application in the field of noncoherent acoustic communications. This work presents results of a tank scale experiment using an algorithm for rapid transmission of binary data in a complex underwater environment with the TRA approach. A simple 15-symbol code provides an example of the simplicity and feasibility of the approach. Covert coding due to the inherent scrambling induced by the environment at points other than the intended receiver is also investigated. The experiments described suggest a high potential in data rate for the time-reversal approach in underwater acoustic communications while keeping the computational complexity low.

Journal Article↗
PubMed2002

Hydrophobic forces between protein molecules in aqueous solutions of concentrated electrolyte.

Protein-protein interactions have been measured for a mutant (D101F) lysozyme and for native lysozyme in concentrated solutions of ammonium sulfate at pH 7 and sodium chloride at pH 4.5. In the mutant lysozyme, a surface aspartate residue has been replaced with a hydrophobic phenylalanine residue. The protein-protein interactions of D101F lysozyme are more attractive than those of native lysozyme for all conditions studied. The salt-induced attraction is correlated with a solvation potential of mean force given by the work required to desolvate the part of the protein surfaces that is buried by the protein-protein interaction. This work is proportional to the aqueous surface-tension increment of the salt and the fractional non-polar surface coverage of the protein. Experimental measurements of osmotic second virial coefficients validate a proposed potential of mean force that ascribes the salt-induced attraction between protein molecules to an enhancement of the hydrophobic attraction. This model provides a first approximation for predicting the protein-protein potential of mean force in concentrated aqueous electrolyte solutions; this potential is useful for determining solution conditions favorable for protein crystallization.

Chemical Precipitation↗
PubMed2002

[Expert assessment of oropharyngeal dysphagia].

The number of patients with chronic dysphagia is increasing as more patients with neurologic diseases and carcinomas of the head and neck can be successfully treated and survive. The expert assessment of a dysphagia should be based not only on anamnestic data, as proposed by the German guidelines "Anhaltspunkte für die ärztliche Gutachtertätigkeit im sozialen Entschädigungsrecht und nach dem Schwerbehindertengesetz," but also on clinical, endoscopic, and radiologic examinations. Modern procedures of treatment enable us to prevent aspiration or insufficient nutrition; nevertheless, dysphagia causes severe limitations for the patients.

Chronic Disease↗
PubMed2001

Group A streptococcal growth phase-associated virulence factor regulation by a novel operon (Fas) with homologies to two-component-type regulators requires a small RNA molecule.

A novel growth phase-associated two-component-type regulator, Fas (fibronectin/fibrinogen binding/haemolytic activity/streptokinase regulator), of Streptococcus pyogenes was identified in the M1 genome sequence, based on homologies to the histidine protein kinase (HPK) and response regulator (RR) part of the Staphylococcus aureus Agr and Streptococcus pneumoniae Com quorum-sensing systems. The fas operon, present in all 12 tested M serotypes, was transcribed as polycystronic message (fasBCA) and contained genes encoding two potential HPKs (FasB and FasC) and one RR (FasA). Downstream of fasBCA, we identified a small 300 nucleotide monocistronic transcript, designated fasX, that did not appear to encode true peptide sequences. Measurements of luciferase promoter fusions revealed a growth phase-associated transcription of fasBCA and fasX, with peak activities during the late exponential phase. Insertional mutagenesis disrupting fasBCA and fasA led to a phenotype similar to agr-null mutations in S. aureus, with prolonged expression of extracellular matrix protein-binding adhesins and reduced expression of secreted virulence factors such as streptokinase and streptolysin S. In addition, fasX transcription was dependent on the RR FasA; however, deletion mutagenesis of fasX resulted in a similar phenotype to that of the fasBCA or fasA mutants. Complementation of the fasX deletion mutant, with the fasX gene expressed in trans from a plasmid, restored the wild-type fasBCA regulation pattern. This strongly suggested that fasX, a putative non-translated RNA, is the main effector molecule of the fas regulon. However, using spent culture supernatants from wild-type and fas mutant strains, we were not able to show an influence on the logarithmic growth phase expression of fas and dependent genes. Thus, despite structural and functional similarities between fas and agr, to date the fas operon appears not to be involved in group A streptococcal (GAS) quorum-sensing regulation.

Amino Acid Sequence↗
PubMed2001

Incidence and impact of systemic venous collateral development after Glenn and Fontan procedures.

BACKGROUND: Development of systemic venous collaterals after Glenn or Fontan procedures can lead to systemic desaturation and reduction in ventricular function, resulting in impaired everyday performance in patients with univentricular heart disease. METHODS: We analyzed 79 patients who had undergone a Glenn or Fontan procedure between 1995 and 1999 for the incidence and predilection sites of systemic venous collaterals as well as the therapeutic options. RESULTS: In 16/79 (= 20.2%) patients, 19 veno-venous connections were detected 310 days (1-966 days) postoperatively. Locations were: brachiocephalic angles/pericardial veins (7), azygos/hemiazygos system (5), Thebesian veins (2), epidiaphragmatic veins (5). Drainage was to the pulmonary veins in 5, to the "left" atrium in 9, and to the IVC system in 5 patients. An isolated intervention became necessary because of low saturations in 5/16 pts, with improvement in all of them (catheter embolization 4, surgical closure 1). CONCLUSIONS: After Glenn or Fontan operations, the increased central venous pressure may induce recanalization of embryologically preformed and obliterated vessels. Their predilection sites must be carefully evaluated pre- and postoperatively. During surgical procedures, potential venous channels should be ligated. Interventional or surgical closure of collaterals may become necessary.

Adolescent↗
PubMed2001

Aortic valve preservation in acute type A dissection: mid-term results.

BACKGROUND AND AIM OF THE STUDY: The study aim was to evaluate the long-term effectiveness of a strategy for managing the aortic valve, aortic root and ascending aorta according to the pathology in acute aortic type A dissection. Results after surgery for acute type A dissection with preservation of the aortic valve were reviewed. METHODS: The patient group included 57 hospital survivors operated on according to a surgical strategy of aortic valve resuspension and supracoronary ascending aortic graft implantation. Reinforcement of the aortic stumps with gelatin-resorcinol-formaldehyde glue was performed in all patients. Aortic valve function in all survivors was investigated by echocardiographic follow up at 30 days, 6 and 12 months after surgery, and yearly thereafter. RESULTS: During the follow up period, nine patients (16%) died without reoperation. Actuarial probability of freedom from reoperation for aortic valve failure in the complete series was estimated as 100% after both 30 days and 12 months. Postoperatively, one patient underwent reoperation 14 months for aortic regurgitation, and three patients for aortic regurgitation with sinus of Valsalva dilatation between 48 and 88 months. The hospital mortality rate at reoperation was 50% (n = 2). CONCLUSION: Valve-sparing surgery is possible and can be recommended for the majority of patients with acute type A aortic dissection.

Actuarial Analysis↗
PubMed2000

[Stroke unit at a medical clinic providing general medical care. Model and initial clinical results].

BACKGROUND AND OBJECTIVES: To achieve in Germany complete therapeutic cover for patients after a stroke, models will have to be formulated that incorporate such units within the confines of departments of general medicine, where most stroke patients are at present being treated. Preliminary experience of such a unit is reported here. PATIENTS AND METHODS: The stroke unit, conceived for "mixed assessment", has 6 beds within a normal ward but an increased number of specially trained personnel and specialized equipment. The aim was the rapid diagnosis, targeted treatment, monitoring, early mobilization and, if necessary, smooth and direct transfer to an installation for rehabilitation to which the patient can be taken during the entire stay in the acute stroke unit. RESULTS: During a period of 11 months 120 patients (68 men, 52 women; mean age 71 years) were treated in the stroke unit, 47% having been admitted within 3 hours of the acute episode. An acute ischaemic attack had occurred in 85%, cerebral haemorrhage in 15%. The median European stroke scale (ESS) was 76 on admission, 90.5 on discharge, the Barthel index 45 and 90, the ranking scale 3.2 and 2.3, respectively. The complication rate per patient during hospital stay was 0.5. There were 12 deaths (10%), 22.2% among those with cerebral bleeding, 7.7% of those with ischaemia. Mean hospital stay was 13.3 days. 57.4% patients were transferred to a rehabilitation unit, 34.2% discharged home, 2.8% directly to a nursing home. The remaining 6 had undergone immediate vascular (4) or neurological (2) procedures. CONCLUSION: A "mixed assessment" stroke unit within a general medical department is feasible. It improves working conditions and patient care as well as reducing the length of hospital stay.

Acute Disease↗
PubMed2000

Decontamination of a Mycoplasma-infected Chlamydia pneumoniae strain by pulmonary passage in SCID mice.

We describe a procedure to eliminate contaminating Mycoplasma from Chlamydia pneumoniae (C. pneumoniae) cultures by pulmonary passage in severe combined immunodeficiency mice (SCID). Four weeks after experimental infection only C. pneumoniae could be cultured from the lungs of the infected animals while Mycoplasma could not be detected any longer, as shown by PCR, culture and transmission electron microscopy (TEM).

Animals↗
PubMed2000

[Hearing screening in newborn infants. Comparative studies and cost analysis with different instruments].

BACKGROUND: The necessity of screening examinations in newborns today cannot be denied. Up to now, it has only been achieved in a few countries to introduce a general hearing screening for newborns. METHODS: We examined 100 newborns (200 ears) at their third day of life. All ears were evaluated with the TEOAE-screening-device ECHOSCREEN. In addition, we carried out BERA screening examinations with the ALGO PORTABLE or with the EVOFLASH on 100 of these 200 ears. As a reference method, we utilized TEOAE-examinations with the ILO-88 for all ears. RESULTS: 4.5% of the 200 ears examined with the ECHOSCREEN were conspicuous due to accumulation of earwax problems. With the ALGO-system, none of the ears was conspicuous. Among the 100 ears examined with the EVOFLASH we found negative results with seven ears (4 children). These findings will be discussed in detail. Furthermore, we analyzed the costs for one-step- and two-step-screenings. Costs for a one-step-screening of both ears would be DM 14.27 with Echoscreen, DM 44.69 with ALGO, DM 32.19 with Evoflash for one patient including material and personnel costs. Costs for a two-step-screening would be DM 16.28 with Echoscreen and ALGO, DM 15.72 with Echoscreen and Evoflash, calculated per child on the basis of 812,173 newborn children in the year 1997 in Germany. CONCLUSION: On the basis of all these results, we recommend a two-step-screening with TEOAE and BERA-devices.

Audiometry, Evoked Response↗
PubMed2000

Severe Chlamydia pneumoniae infection in patients with neutropenia: case reports and literature review.

Three cases of life-threatening C. pneumoniae infection in patients with acute leukemia and treatment-induced neutropenia are described. Diagnosis was made on the basis of the detection of C. pneumoniae-DNA, complemented by serology. The role of the widely distributed respiratory tract pathogen C. pneumoniae in febrile neutropenia is poorly understood, and studies are needed to estimate the frequency of severe pulmonary infection caused by this agent in patients with neutropenia.

Adolescent↗
PubMed1999

Bilateral optic neuropathy with IgGkappa multiple myeloma improved after myeloablative chemotherapy.

A 49-year-old woman with immunoglobulin GK multiple myeloma developed progressive visual loss with bilateral upper and lower central arcuate scotomas. Funduscopic and electrophysiologic studies indicated bilateral optic neuropathy. The immunoglobulin G fraction of the patient's serum reacted with retinal ganglionic cells in bovine retina. The visual abnormalities remitted after myeloablative chemotherapy and disappearance of the paraprotein.

Animals↗
PubMed1999

Endotoxin release due to ciprofloxacin measured by three different methods.

Antibiotics are known to induce the release of bioactive endotoxin (LPS) from gram-negative bacterial cells. Because varying data have been published on the influence of quinolone antibiotics on LPS liberation, we studied the effect of ciprofloxacin on a culture of Escherichia coli by determining bacterial killing and free LPS concentrations in comparison with imipenem and ceftazidime. LPS levels were measured by three different methods, namely (1) the Limulus amebocyte lysate test, (2) an ELISA method based on capture of LPS by monoclonal antibodies, and (3) indirect determination by measuring the ability of antibiotic-induced LPS to trigger TNFalpha release from a monocytic cell line. With both the Limulus and ELISA tests, a low endotoxin-releasing activity of ciprofloxacin was confirmed. In contrast to previous studies, this LPS also had low bioactivity in terms of TNFalpha induction. Limulus LPS determinations correlated more precisely with LPS bioactivity than did ELISA values, an observation which underlines the crucial role of LPS determination methods in studies of antibiotic-induced LPS release.

Anti-Infective Agents↗
PubMed1998

Effects of cardiopulmonary bypass and inhaled nitric oxide on platelets in children with congenital heart defects.

UNLABELLED: Nitric oxide (NO) reduces platelet aggregation in vitro. However, repeated measurements of platelet aggregation in infants and small children are impossible due to the large blood samples required. Instead, the expression of different platelet receptors mediating platelet adhesion (CD 36 and CD 42b), activation (CD 42b and CD 61) and aggregation (CD 41a) was measured repeatedly by flow cytometry. First, the expression of platelet receptors was quantified in platelet suspensions of 20 healthy volunteers after incubation with different concentrations of NO (0, 25, 100 and 640 ppm) and compared to changes in platelet aggregation and intrathrombocytic cGMP levels. It was then studied in 21 infants and children before, during and up to 3 days after cardiopulmonary bypass surgery. Seven of these patients required NO inhalation postoperatively. The in vitro experiments showed a reduced expression of the CD 41a, CD 42b and CD 61 receptors with increasing doses of NO, predominantly affecting the CD 41a receptor (-11% at 100 ppm and -20% at 640 ppm). This significant effect is in keeping with the observed NO-induced inhibition of platelet aggregation (-44% at 100 ppm) and the rise in platelet cGMP levels (+69% at 100 ppm). In patients without inhaled NO, the expression of CD 41a was slightly attenuated during cardiopulmonary bypass surgery (-15%) but increased significantly afterwards (2 h: +31%, 1st day: +129%, 2nd day: +120%, 3rd day: +111%). Comparable results were obtained regarding the other adhesion molecules CD 36, CD 42b and CD 61. In patients with inhaled NO the same pattern was observed and analysis of variance did not reveal any significant difference between both groups of patients. CONCLUSIONS: NO (> or = 100 ppm) decreases the expression of different platelet adhesion molecules and platelet aggregation, presumably via an increase in intracellular cGMP. However, due to the low dose range used in the clinical setting (1-40 ppm) this is clinically not relevant. Immediately after cardiopulmonary bypass surgery the expression of these adhesion molecules is reduced, but recovers on the 1st postoperative day.

Administration, Inhalation↗
PubMed1998

Antibacterial activity of meropenem against Pseudomonas aeruginosa, including antibiotic-induced morphological changes and endotoxin-liberating effects.

The in vitro effects of meropenem on Pseudomonas aeruginosa were examined by studying (i) the inhibitory and bactericidal concentrations of meropenem versus those of imipenem for clinical isolates; (ii) changes in bacterial morphology during in vitro culture; and (iii) release of endotoxin induced by meropenem compared with that induced by other antipseudomonal compounds. Meropenem MIC90 and MBC90 values for 108 clinical isolates were 2 and 4.8 mg/l compared to 4.5 and 9.6 mg/l for imipenem. Morphological studies using phase-contrast and scanning electron microscopy showed that meropenem induced the formation of indeterminate bacterial cell forms at drug concentrations of 1-2.5 mg/l (0.5- to 1.25-fold the MIC), while spheroplasts predominated at drug levels exceeding 5 mg/l (2.5-fold the MIC). Determination of free and EDTA-releasable endotoxin activity by means of the Limulus lysate test showed that both meropenem and imipenem liberated significantly less endotoxin than did ceftazidime. Therefore, although meropenem binds to penicillin-binding proteins (PBPs) 2 and 3 (in contrast to imipenem, which binds to PBP2 only), endotoxin release should not be a cause of concern when treating systemic gram-negative infections with this drug.

Anti-Infective Agents↗
PubMed1998

Surgical treatment of Marfan patients with aneurysms and dissection of the proximal aorta.

BACKGROUND: The authors retrospectively analyzed early and late results of surgical treatment for 79 Marfan patients with aneurysms and dissection of the proximal aorta. METHODS: From September 1979 to February 1996, 79 patients with Marfan syndrome underwent aortic root replacement using composite grafts (n=68, Bentall-technique 63, button-technique 5), and ascending aortic replacement with a valve-sparing procedure (n=11). There were 12 patients (15.2%) who simultaneously received partial or total arch replacement. 55 patients (69.6%) were male, and 24 female (30.4%). The average age was 33.8 years. Forty-one patient (51.9%) had non-dissecting aneurysms while the remaining 38 patients suffered from either acute (24.0%) or chronic aortic dissection (24.0%). The aortic valve was involved in 97.5% of all cases. RESULTS: The total early mortality (< or =30 days) was 3.8%, 10.5% for acute aortic dissection and 2.4% for non-dissecting aneurysms. There were no early postoperative deaths in patients after valve-sparing operation and in those with chronic aortic dissection. The follow-up rate was 98.7%. During a mean follow-up of 68+/-25 months 10 patients (13.3%) died and cardiac complications were a common cause of the late deaths. There was no late mortality in the valve-sparing operations during a mean follow-up period of 8+/-6 months, however, 1 required valve replacement. 19 (25.3%) of the 75 patients surviving late have undergone 25 secondary operations on the cardiovascular system. Reoperations at aortic sites distant from the original were much more frequent after primary repair for acute and chronic dissection when compared to non-dissecting aneurysms (p<0.005). Actuarial survival rate of all patients with composite graft replacement including early deaths was 91.2% at 1 year, 84.4% at 5 years and 75.2% at 10 years. CONCLUSIONS: Composite graft insertion has become the gold standard for treating Marfan-patients with non-dissecting and dissecting aneurysms of the aortic root. Our early experience in 11 patients with valve-sparing procedures indicated that this,variant may be the better choice in selected patients.

Adult↗