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Biomedical subjects

A Kramer

Publications and source records attributed to A Kramer.

At least 109 records · Page 6Linked to original sources
PubMed1998

Effects of an angiotensin II antagonist on ischemic and nonischemic isolated rat hearts.

BACKGROUND: Increasing evidence suggests that a locally integrated or intramyocardial renin-angiotensin system plays a significant role in ischemia-reperfusion injury. We evaluated the effects of losartan, an angiotensin II type 1 receptor blocking agent, on ischemic and nonischemic isolated rat hearts. METHODS: Using the modified Langendorff model, hearts were perfused with either low or high doses of losartan (18.2 mmol/L or 182.2 mmol/L, respectively) or with saline added to Krebs-Henseleit solution during phase I of the study. During phase II, hearts were exposed to a 60-minute period of global ischemia. Ischemic arrest was induced with warm cardioplegic solution (KCl, 16 mEq/L) containing either high-dose losartan (182.2 mmol/L) or Krebs-Henseleit solution only. RESULTS: During phase I of the study, no statistically significant differences were observed between the low-dose losartan group and the control group. However, hearts treated with high-dose losartan demonstrated an increase in peak systolic pressure, maximum first derivative of pressure, pressure-time integral, coronary flow, and oxygen consumption (p < 0.0001). During phase II, hearts treated with losartan showed a significantly better recovery on reperfusion, as reflected by better contractility (p < 0.001), higher oxygen consumption (p < 0.001), higher coronary flow (p < 0.0001), and lower creatine phosphokinase levels (41.1 +/- 1.7 versus 73.3 +/- 5.6 U/L; p < 0.001). CONCLUSIONS: High doses of losartan have a positive inotropic effect on normally perfused hearts. Given in cardioplegic solution, the drug has a significant protective effect on ischemic isolated rat hearts.

Angiotensin II↗
PubMed1998

Stepwise transformation of a cholera toxin and a p24 (HIV-1) epitope into D-peptide analogs.

We have transformed two peptide epitopes into D-peptide analogs: VPGSQHIDS derived from cholera toxin recognized by the antibody TE33, and GATPQDLNTML from the HIV-1 capsid protein p24 recognized by the antibody CB4-1. The transformation process was performed by stepwise substitution of each single epitope position by all 19 D-amino acids and glycine followed by antibody binding studies and selection of one D-analog for further transformation. Thus, each transformation step introduced one novel D-position into the peptide. For both epitopes complete D-analogs were obtained. The cholera toxin-derived variant dwGsqhydp binds to the antibody TE33 with higher affinity than its original epitope, whereas in the case of the p24-derived analog saGdwwGkssl lower affinity was detected. Both D-peptides are completely stable in serum for several days. Antibody interaction models for both D-molecules were generated by computer-assisted modelling based on the crystal structures of the starting complexes. Compared with the L-peptides, the binding conformation of dwGsqhydp is very similar, whereas saGdwwGkssl displays a completely different interaction mode.

Amino Acid Sequence↗
PubMed1998

Pediatric spinal deformity.

Pediatric spinal deformity is a common problem facing the pediatrician and orthopedic surgeon. Most commonly seen is idiopathic scoliosis. Early diagnosis and treatment are important. Although the etiology of idiopathic scoliosis remains unclear, there continues to be a search for genetic markers and studies for the modes of inheritance. Idiopathic scoliosis is more clearly understood recently and is recognized as a complex three-dimensional deformity. Prognostic indicators for juvenile scoliosis have been identified. Surgical management of idiopathic scoliosis continues to evolve, and now a thoracoscopic endoscopic technique is available. Long-term follow-up has demonstrated generally satisfactory results with spinal fusion surgery. Other syndromes such as Klippel-Feil, familial dysautonomia, and Marfan syndrome demonstrate high rates of scoliotic deformities. Most are unresponsive to bracing and most often require surgical intervention. Although primary spinal neoplasms are uncommon, most are benign, and outcomes are generally satisfactory.

Braces↗
PubMed1998

Asthma and allergies among children in West and East Germany: a comparison between Münster and Greifswald using the ISAAC phase I protocol. International Study of Asthma and Allergies in Childhood.

The study aim was to compare the prevalence of asthma, rhinitis and eczema in children living in Münster, western Germany, and Greifswald, eastern Germany, and to investigate associations of several characteristics and exposures with atopic disease symptoms. In 1994 and 1995, questionnaire information was gathered on 5-8 yr old children (n=3,741 in Münster and n=2,857 in Greifswald) and 12-15 yr olds (n=4,003 and n= 3,153, respectively) using the phase I protocol of the International Study of Asthma and Allergies in Childhood (ISAAC). The 12 month period prevalences of reported atopic disease symptoms in 5-8 yr olds were generally higher in Münster than in Greifswald, whereas only a few prevalence differences were observed in 12-15 yr olds. In both age groups the reported lifetime prevalences of asthma, hay fever and eczema were lower in Greifswald. Indoor exposures such as wood or coal heating and feather bedding were negatively associated with symptoms, whereas exposures such as truck traffic in a residential street or active smoking were positively associated with symptoms. Wood or coal heating could partly explain the prevalence difference of allergic rhinitis symptoms among 5-8 yr olds between Münster and Greifswald. The findings provide additional evidence for a role of several characteristics and exposures as potential determinants of asthma and allergies in children.

Adolescent↗
PubMed1998

[Antiseptic efficacy and acceptance of Octenisept computed with common antiseptic mouthwashes].

The efficacy of common antiseptic mouth rinses was evaluated in a study with healthy volunteers. Octenisept and Cetylpyridiniumchlorid had a significant stronger impact on the microbial burden of the oral cavity than Chlorhexidin (Corsodyl) immediately and 10 min after the application. Dobendan (contains Cetylpyridiniumchlorid) showed a better antimicrobial effect than Corsodyl immediately after application, after 10 min an increasing loss of efficacy was noted. The antiseptic efficacy of hexetidin-based Gurfix was very similar to the efficacy observed with Corsodyl from the start of the antiseptic treatment until 1 h later. Acriflavine-solution (0.2% m/v) was significantly less efficient after 10, 30 and 60 min compared to Corsodyl. The antimicrobial impact of Fluomint-Lysoform was very similar to the effect of rinsing with dest. sterile water. A subjective assessment of taste and smell of the mouth rinse solutions concludes the evaluation. Further methodological aspects for a common test guideline for antiseptic mouth rinse solutions are discussed.

Adult↗
PubMed1998

[Cardiac rhythm and systemic embolism in long-term follow up of patients with non-valvular paroxysmal atrial fibrillation].

BACKGROUND: Paroxysmal atrial fibrillation may predispose to systemic embolism. There is little information about the evolution of cardiac rhythm and the occurrence of new embolic events in these patients. AIM: To report the results of a long term follow up of patients with paroxysmal atrial fibrillation. PATIENTS AND METHODS: Patients consulting for non valvular paroxysmal atrial fibrillation were followed for a mean period of 5 years. An EKG, 2D echocardiogram and brain CT scans were performed on admission and at the end of the follow up period to all patients. RESULTS: Sixty eight patients aged 65 +/- 1.5 years were studied. Thirty two had an idiopathic atrial fibrillation, 28 had a history of mild hypertension and 8 had a history of coronary artery disease. Evidence of systemic emboli was found in 17 patients at entry (to the brain in 14 patients). During the follow up 87% of patients required antiarrhythmics, 27% were anticoagulated and 28% received aspirin. Five patients had new embolic episodes. Of these, four had a history of prior embolism. Forty one percent of patients continued in sinus rhythm and remained asymptomatic, 32% had at least one recurrence of paroxysmal atrial fibrillation and nine patients evolved to chronic atrial fibrillation. Five patients required a permanent pacemaker due to symptomatic bradycardia. CONCLUSIONS: Most patients with non valvular paroxysmal atrial fibrillation remain in sinus rhythm but one third have recurrences of the arrhythmia. A main risk factor for embolism is the history of previous embolic episodes.

Aged↗
PubMed1997

Molecular basis for the binding promiscuity of an anti-p24 (HIV-1) monoclonal antibody.

Multiple binding capabilities utilized by specific protein-to-protein interactions in molecular recognition events are being documented increasingly but remain poorly understood at the molecular level. We identified five unrelated peptides that compete with each other for binding to the paratope region of the monoclonal anti-p24 (HIV-1) antibody CB4-1 by using a synthetic positional scanning combinatorial library XXXX[B1,B2,B3,X1,X2,X3]XXXX (14 mers; 68,590 peptide mixtures in total) prepared by spot synthesis. Complete sets of substitution analogs of the five peptides revealed key interacting residues, information that led to the construction of binding supertopes derived from each peptide. These supertope sequences were identified in hundreds of heterologous proteins, and those proteins that could be obtained were shown to bind CB4-1. Implications of these findings for immune escape mechanisms and autoimmunity are discussed.

Amino Acid Sequence↗
PubMed1997

Crystallographic analysis of anti-p24 (HIV-1) monoclonal antibody cross-reactivity and polyspecificity.

The X-ray crystal structures of an anti-p24 (HIV-1) monoclonal antibody Fab fragment alone and in complexes with the epitope peptide GATPQDLNTnL (n = norleucine), an epitope-homologous peptide GATPEDLNQKLAGN, as well as two unrelated peptides GLYEWGGARITNTD and efslkGpllqwrsG (D-peptide), are presented to a maximum resolution of 2.6 A. The latter three peptides were identified from screening synthetic combinatorial peptide libraries. Although all peptides bind to the same antigen combining site, the nonhomologous peptides adopt different binding conformations and also form their critical contacts with different antibody residues. Only small readjustments are observed within the framework of the Fab fragment upon binding.

Amino Acid Sequence↗
PubMed1997

Anti-tumor necrosis factor-alpha improves myocardial recovery after ischemia and reperfusion.

OBJECTIVES: This study sought to assess the importance of locally released or paracrine myocardial tumor necrosis factor-alpha (TNF-alpha) in the evolution of postischemic myocardial dysfunction and to use immunohistochemical studies to localize TNF-alpha within the myocardium. BACKGROUND: TNF-alpha is implicated as a systemic mediator in the development of myocardial ischemia-reperfusion injury by promoting leukocyte myocardial infiltration, and it has been shown to originate from noncardiac peripheral mononuclear cells. We have recently documented in a blood-free environment the release of TNF-alpha from the ischemic-reperfused myocardium. METHODS: Isolated rat hearts undergoing 1 h of global cardioplegia-induced ischemia and 30 min of reperfusion were investigated with use of the modified Langendorff model. Hearts were randomly divided into three subgroups: group A, control group; and groups B and C, isolated hearts receiving cardioplegic solution containing monoclonal hamster antimurine TNF-alpha antibodies (group B) or hamster IgG (group C). RESULTS: Significant amounts of TNF-alpha were detected in group A and group C effluent on 1 min of reperfusion (752 +/- 212 and 958 +/- 409 pmol/ml, respectively). However, in group B, TNF-alpha was below detectable levels. In this group, postischemic left ventricular peak systolic pressures, first derivative of the rise in left ventricular pressure (dP/dtmax), pressure-time integral, coronary flow and O2 consumption improved (analysis of variance [ANOVA] p < 0.0001 for all variables) compared with values in groups A and C; creatine kinase levels decreased (p < 0.005); and myocardial structure was preserved. Immunohistochemical staining localized TNF-alpha to cardiac myocytes and to endothelial cells. CONCLUSIONS: Anti-TNF-alpha neutralizes local TNF-alpha release from cardiac myocytes after ischemia and improves myocardial recovery during reperfusion, indicating that postischemic paracrine TNF-alpha release plays an active role in myocardial dysfunction.

Animals↗
PubMed1997

High-dose isosorbide dinitrate for myocardial revascularization with composite arterial grafts.

BACKGROUND: Composite arterial grafting for myocardial revascularization is a surgical technique in which free arterial conduits are proximally attached to an in situ internal mammary artery. METHODS: Composite arterial grafting was performed in 78 patients with internal mammary artery (n = 24), inferior epigastric artery (n = 21), or radial artery (n = 33) connected to the internal mammary artery. Overall, 254 distal anastomoses were performed (average number, 3.3 per patient), 225 of which were arterial. All patients were treated postoperatively with high-dose isosorbide dinitrate (4 to 20 mg/h for 24 hours). RESULTS: The in-hospital mortality rate was 2.6% (2 patients). Early recatheterization studies performed 3 weeks (range, 1 to 20 weeks) after operation in 30 patients demonstrated patency rates of 100%, 93%, and 100% for the composite internal mammary artery, inferior epigastric artery, and radial artery groups, respectively. In addition, two inferior epigastric artery conduits had major intraluminal constriction. At a mean follow-up of 20 months (range, 1 to 42 months) all patients are alive, and all but 2 in the inferior epigastric group (97%) are angina free. CONCLUSIONS: This surgical technique can be safely used. On the basis of our experience, the right internal mammary artery and the radial artery are the most suitable conduits for this procedure. High-dose nitrates given perioperatively prevent spasm and ensure early patency rates.

Adult↗
PubMed1997

Is repression adaptive? Relationships to socioemotional adjustment, academic performance, and self-image.

Of 74 high school students rated on a repression-sensitization continuum, the 17 identified as "repressors" were found to have greater frustration tolerance, better social skills, higher educational performance, and less shy and withdrawn behavior when compared to the 40 identified as intermediates; they also had a greater sense of global self-worth and higher self-image in the scholastic and social content domains. The 17 students identified as "sensitizers" did not differ from intermediates on measures of classroom performance or self-image. Results are discussed in relation to earlier reports of repression as maladaptive.

Adaptation, Psychological↗
PubMed1997

Prophylactic use of topical anti-infectives in ophthalmology.

The prophylactic use of topical anti-infectives is indicated on the eye (1) prior to any surgery on the eye, by periorbital and conjunctival administration and, if required, intraoperatively as well; (2) in the form of the Credé prophylaxis against ophthalmia neonatorum; (3) with accidental pathogenic contamination of the eye; (4) to prevent conjunctivitis by intensive care surgical patients; (5) for the antiseptic irrigation of donor bulbi prior to keratoplasty, and (6) if required, to prevent ocular infection in a given epidemiological situation. The drug of first choice is polyvinylpyrrolidone-iodine at a concentration ranging from 1.5 to 5%. Another topical anti-infective is a 0.02 or 0.01% solution of polyhexanide, a promising medication, currently in the process of being approved.

Animals↗
PubMed1997

Respiratory syncytial virus immune globulin treatment of RSV lower respiratory tract infection in previously healthy children.

OBJECTIVE: To evaluate the efficacy of high titer respiratory syncytial virus (RSV) immune globulin (RSVIG) in the treatment of previously healthy children hospitalized with proven RSV lower tract infection (LRI). METHOD: Infants and young children </=2 years of age with RSV LRI of </=4 days duration, and respiratory scores >/=2. 5 were enrolled. RESULTS: One hundred and one previously healthy children hospitalized with RSV LRI received either 1500 mg/kg of RSVIG (RespiGam, MedImmune Inc, Gaithersburg, MD) or albumin placebo in a randomized, double-blind, placebo-controlled trial. Forty-six RSVIG and 52 recipients of placebo met all eligibility criteria. Demographic characteristics of the two groups were similar. More RSVIG recipients (46% vs 29%) had an SaO2 </=85% at entry than did placebo recipients, but a higher proportion of placebo recipients required intensive care unit (ICU) care and mechanical ventilation at study entry. The mean RSV hospital stay was 5.52 +/- 0.69 days (SE) for placebo and 4.58 +/- 0.40 days for RSVIG. Additionally, there was an interaction between treatment group and entry respiratory score, which led to subgroup analysis. Children with modest respiratory illness did not receive any benefit from RSVIG therapy. RSVIG recipients with more severe illness (entry respiratory scores >/=3.0) had 1.6 fewer hospital days and 2.7 days less ICU stays. CONCLUSION: RSVIG infusions seemed safe and generally well tolerated. Although some beneficial effect trends were seen for those with more severe disease who were treated there was no evidence that treatment with RSVIG resulted in reduced hospitalization and reduced ICU stays in all children with RSV disease.

Bronchiolitis↗
PubMed1996

[Systemic Nocardia asteroides infection with endocardial involvement in a patient undergoing immunosuppressive therapy].

HISTORY: A 62 year-old male patient developed malaise, unproductive cough and high temperature (39.5 degrees C) during immunosuppressive therapy with methylprednisolon and cyclosporin A six months after kidney transplantation for glomerulonephritis. INVESTIGATIONS: Clinical examination revealed an endophthalmitis and chest X ray a left-sided lobar pulmonic infiltration. Computed tomography and magnetic resonance imaging examination performed because of recurrent petit-mal-convulsions demonstrated multiple intracranial infiltrations. Transoesophageal echocardiography revealed floating vegetations up to 8 mm in diameter predominantly attached to the aortic valve. A total of 39 consecutive blood cultures drawn during several days remained sterile. However, Nocardia asteroides (Biovar A1) was isolated from a small cutaneous tumor excised from the right thigh. TREATMENT AND COURSE: After initiation of a specific antibiotic treatment with imipenem/cilastatin (each 1 g three times daily), and doxycyclin (100 mg twice daily), computed tomography and magnetic resonance imaging showed a reduction in size and number of the intracranial infiltrations. Neurological symptoms were progressive despite maximal anticonvulsant therapy. The patient died 83 days after hospital admission from an epileptic state resistant to therapy. CONCLUSION: Though nocardiosis is still rare, it should early be included in the differential diagnosis of infections in immunocompromised patients to allow timely diagnosis and therapy.

Anti-Bacterial Agents↗