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Biomedical subjects

A Kramer

Publications and source records attributed to A Kramer.

At least 55 records · Page 3Linked to original sources
PubMed2000

Bilateral skeletonized internal thoracic artery grafting in 303 patients seventy years and older.

OBJECTIVES: Higher patency rates of the internal thoracic artery have led myocardial revascularization with bilateral internal thoracic arteries to be a procedure designated primarily for young patients. Fewer leg wound complications and sternal collateral flow preservation with the skeletonizing dissection technique can make bilateral internal thoracic artery grafting attractive also for elderly patients. METHODS: Between May 1996 and May 1998, 303 consecutive patients aged 70 years or older (mean age 75.5 years; range 70-92 years) underwent coronary artery bypass grafting with double skeletonized internal thoracic arteries. Forty-four (14.5%) patients were 80 years or older, and 89 (28%) had diabetes. The mean number of grafts was 3.1 per patient (2-6). RESULTS: Operative mortality was 2.6% (n = 8): it was higher for octogenarians (6.8%) than for younger patients (1.9%) (P =.06). The only significant preoperative predictors of early mortality were complicated percutaneous transluminal coronary angioplasty (P =.03) and preoperative use of intra-aortic balloon pumping (P =.03). Six patients (2%) had sternal wound infections for which chronic lung disease (P =.02) and emergency operation (P =.006) were the only significant predictors. Twenty-two (7.2%) late deaths occurred, and 1- and 3-year survivals were 93% and 90%, respectively. The 3-year survival of patients 80 years old or older was 92%. CONCLUSIONS: Bilateral grafting of the skeletonized internal thoracic artery carries relatively low morbidity and mortality in elderly patients and can be recommended for selected patients including octogenarians.

Aged↗
PubMed2000

An innovative topical drug formulation for wound healing and infection treatment: in vitro and in vivo investigations of a povidone-iodine liposome hydrogel.

BACKGROUND: In topical wound treatment, the combination of anti-infectious therapy and a healing-promoting moisturization has not been accomplished yet. OBJECTIVE: Evaluation of a new topical drug consisting of a povidone-iodine (PVP-I) liposome hydrogel allowing for both antiseptic and moist treatment. METHODS: Pharmaceutical formulation of a complex of PVP-I (3%) and phosphatidylcholine in a hydrogel. In vitro, interaction of the complex with relevant micro-organisms was analysed by electron microscopy. Antimicrobial activity was investigated using Staphylococcus aureus in a suspension test. Tissue toxicity was examined by an explantation test in a rodent model. A randomized clinical study on efficacy and tolerability in wound healing was carried out on 35 patients with mesh grafts in parallel groups (PVP-I liposome hydrogel vs. Bactigras) for proof of concept in humans. RESULTS: A direct interaction of the PVP-I liposomes with micro-organisms by attachment to the cell surface was documented. A significantly better microbicidal activity and tissue tolerability of the PVP-I liposome hydrogel compared to conventional PVP-I formulations was shown. The results of the clinical study, especially measurements of neo-epithelization per time and transplant loss, demonstrate significant differences in favour of the PVP-I liposome hydrogel. CONCLUSION: The novel PVP-I liposome hydrogel combines microbicidal and wound healing activities resulting in enhanced epithelization.

Anti-Infective Agents, Local↗
PubMed2000

Prophylactic and therapeutic application of antimicrobial agents in the oral cavity.

Antimicrobial substances are used for many prophylactic and therapeutic reasons in the oral cavity. They are used as mouthrinses, for the irrigation of specific oral locations, in form of gels, or varnishes. Different antimicrobial agents are available and some preparations are complex compositions of these compounds. Although it has been proven that several agents are suited to achieve a considerable reduction of oral microorganisms many questions concerning the clinical benefit are yet to be answered. This report summarises the evidence of the efficacy of oral antiseptics (especially chlorhexidine, pvp-iodine, and Listerine) depending on different indications, which is the basis for clinical and practical recommendations.

Anti-Infective Agents↗
PubMed1999

Cross-reactivity of myelin basic protein-specific T cells with multiple microbial peptides: experimental autoimmune encephalomyelitis induction in TCR transgenic mice.

Activation of autoreactive T cells is a crucial event in the pathogenesis of autoimmune diseases. Cross-reactivity between microbial and self Ags (molecular mimicry) is one hypothesis that could explain the activation of autoreactive T cells. We have systematically examined this hypothesis in experimental autoimmune encephalomyelitis using mice bearing exclusively myelin basic protein (MBP)-specific T cells (designated T+ alpha-). A peptide substitution analysis was performed in which each residue of the MBPAc1-11 peptide was exchanged by all 20 naturally occurring amino acids. This allowed the definition of the motif (supertope) that is recognized by the MBPAc1-11-specific T cells. The supertope was used to screen protein databases (SwissProt and TREMBL). By the search, 832 peptides of microbial origin were identified and synthesized. Of these, 61 peptides induced proliferation of the MBPAc1-11-specific transgenic T cells in vitro. Thus, the definition of a supertope by global amino acid substitution can identify multiple microbial mimic peptides that activate an encephalitogenic TCR. Peptides with only two native MBP-residues were sufficient to activate MBPAc1-11-specific T cells in vitro, and experimental autoimmune encephalomyelitis could be induced by immunizing mice with a mimic peptide with only four native MBP residues.

Amino Acid Substitution↗
PubMed1999

Effect of pacing chamber and atrioventricular delay on acute systolic function of paced patients with congestive heart failure. The Pacing Therapies for Congestive Heart Failure Study Group. The Guidant Congestive Heart Failure Research Group.

BACKGROUND: Previous studies of pacing therapy for dilated congestive heart failure (CHF) have not established the relative importance of pacing site, AV delay, and patient heterogeneity on outcome. These variables were compared by a novel technique that evaluated immediate changes in hemodynamic function during brief periods of atrial-synchronous ventricular pacing. METHODS AND RESULTS: Twenty-seven CHF patients with severe left ventricular (LV) systolic dysfunction and LV conduction disorder were implanted with endocardial pacing leads in the right atrium and right ventricle (RV) and an epicardial lead on the LV and instrumented with micromanometer catheters in the LV, aorta, and RV. Patients in normal sinus rhythm were stimulated in the RV, LV, or both ventricles simultaneously (BV) at preselected AV delays in a repeating 5-paced/15-nonpaced beat sequence. Maximum LV pressure derivative (LV+dP/dt) and aortic pulse pressure (PP) changed immediately at pacing onset, increasing at a patient-specific optimal AV delay in 20 patients with wide surface QRS (180+/-22 ms) and decreasing at short AV delays in 5 patients with narrower QRS (128+/-12 ms) (P<0.0001). Overall, BV and LV pacing increased LV+dP/dt and PP more than RV pacing (P<0.01), whereas LV pacing increased LV+dP/dt more than BV pacing (P<0.01). CONCLUSIONS: In this population, CHF patients with sufficiently wide surface QRS benefit from atrial-synchronous ventricular pacing, LV stimulation is required for maximum acute benefit, and the maximum benefit at any site occurs with a patient-specific AV delay.

Aged↗
PubMed1999

Transvenous biventricular pacing for heart failure: can the obstacles be overcome?

Despite increasing evidence of hemodynamic benefit and long-term improvement in clinical status of congestive heart failure (CHF) patients with left ventricular and biventricular pacing, the risks and technical limitations of placing a permanent left ventricular pacing lead have prevented widespread clinical adoption of this therapy. Results of this and other recent investigations suggest it is necessary to target specific sites on the left ventricle to maximize hemodynamic benefit. However, limitations and variations of coronary vein anatomy, as well as patient safety, lead dislodgement, pacing thresholds, lead handling, and ease-of-use issues, present technical challenges for current transvenous permanent pacing lead designs. However, a new transvenous lead system based on an over-the-wire design appears to solve many of these problems and has proved feasible in acute clinical studies.

Animals↗
PubMed1999

Risk assessment of a former military base contaminated with organoarsenic-based warfare agents: uptake of arsenic by terrestrial plants.

Organoarsenic-based chemical warfare agents (CWAs) such as the sternutators diphenylchloroarsine (CLARK I), diphenylcyanoarsine (CLARK II) or phenyldichloroarsine (PFIFFIKUS) still pose a notable risk in countries where former military bases that have stored these weapons have not yet been reclaimed. In fact, this is the case for many countries of Eastern Europe and the CIS. One of the most important military bases of the former Third Reich, the Heeresmunitionsanstalt I and II, is situated close to the German-Polish border at Loecknitz (Fig. 1). The German army stored and decanted different compounds of CWAs at this military base until 1945. When the Soviet Army destroyed the base in 1946, large amounts of CWAs and other organoarsenic compounds polluted the soil. Today up to 250 g (!) of arsenic may be found in 1 kg of soil at some places in this area. Since 1991, a Government Working Group has been working on the risk assessment in order to define the scope of reclamation measures. This study investigates the contamination and the uptake of arsenic by plants because little is known about the bioavailability and metabolism of sternutators and their constituents. The total arsenic concentration of nine different species of terrestrial plants with at least six samples per species is presented. In spite of the considerable arsenic contamination of the soil (mean value 923 mg arsenic/kg soil) the plant contamination remained comparably low. The median value of arsenic contamination of the above-ground organs of velvet grass, Holcus lanatus, was 0.7 mg/kg dry wt. and the mean value was 4.3 mg/kg dry wt. due to some highly contaminated samples. The highest arsenic concentration registered was 26 mg/kg dry wt. in a sample of H. lanatus, which was most probably caused by soil particles adhering to the plant. The chemical structure of the arsenic compounds carried by the above-ground plant organs has been determined by gas chromatographic investigations and showed an uptake of triphenyl arsine by the plants.

Arsenic↗
PubMed1999

[Diagnosis and surgical treatment of atrial septal defects in adults].

BACKGROUND AND OBJECTIVE: The value of surgical closure of an atrial septal defect (ASD) in adults is currently under discussion, because the operative risk is thought to be high and there are no reliable data about postoperative change in quality of life. PATIENTS AND METHODS: The case notes of 205 patients (149 women, 56 men, mean age 41.4 years) in whom an ASD had been surgically closed were analysed retrospectively. Preoperative symptoms, complications, arrhythmias, pulmonary artery pressure and the influence of the operative closure on quality of life (criteria of the New York Heart Association [NYHA]) were noted. RESULTS: At the time of diagnosis 138 (66%) of patients had complained of dyspnoea or palpitations, four had sustained a stroke and two had had endocarditis. Atrial fibrillation or flutter was present in 55 (27%). 47 (23%) were in class III or IV (NYHA). Mean age at operation was 42.2 (18-74.9) years. One patient, a woman with pulmonary hypertension, died and one patient suffered a stroke. The number of patients with atrial fibrillation or flutter fell to 31 (15%) postoperatively and 176 patients (86%) moved to a better NYHA class, especially those who had been in class IV. CONCLUSIONS: These data show that surgical closure of ASD in adults is reasonable, because the operative mortality is low, the quality of life is improved postoperatively and there is a reduced incidence of arrhythmias.

Adolescent↗
PubMed1999

[Acute hantavirus infection caused by a genetically newly identified viral strain. Severe and complicated course of hemorrhagic fever with renal syndrome (nephropathia epidemica)].

HISTORY AND CLINICAL FINDINGS: A 49-year-old patient, a hobby hunter, fell ill acutely with joint and limb pain, abdominal pain, nausea and subfebrile temperatures. At hospitalization, the patient was in bad general condition, showing ascites and lid edema, and acute renal failure was diagnosed. INVESTIGATIONS: Laboratory tests revealed marked thrombocytopenia (15,000/ml), leucocytosis, elevated levels of creatinine, blood urea nitrogen and liver enzymes, respectively. Blood gas analysis showed metabolic acidosis. Chest X-ray showed an interstitial fluid accumulation, abdominal ultrasound disclosed ascites and enlarged kidneys as in acute renal failure. Immunologic tests verified the diagnosis of an acute hantavirus infection, by use of specific molecular biology techniques a previously unknown virus strain was identified. TREATMENT AND COURSE: Hantavirus infections in western Europe usually show a benign course. However, in the present case, acute progressive pulmonary failure developed despite effective dialysis so that mechanical ventilation was necessary for several weeks. Dialysis had to be carried out for 17 days. As a complication a severe ulcero-destructive tracheobronchitis developed, caused by Aspergillus fumigatus. After several weeks, both renal and pulmonary function had returned to normal. CONCLUSION: Hantavirus infections may lead to severe and complicated courses also in western Europe. By use of new immunologic and molecular biology techniques a specific diagnosis is possible.

Diagnosis, Differential↗
PubMed1999

Testing for multiple species in fossil samples: an evaluation and comparison of tests for equal relative variation.

Tests for equal relative variation are valuable and frequently used tools for evaluating hypotheses about taxonomic heterogeneity in fossil hominids. In this study, Monte Carlo methods and simulated data are used to evaluate and compare 11 tests for equal relative variation. The tests evaluated include CV-based parametric bootstrap tests, modifications of Levene's test, and modified weighted scores tests. The results of these simulations show that a modified version of the weighted scores test developed by Fligner and Killeen ([1976] J. Am. Stat. Assoc. 71:210-213) is the only test that maintains an acceptable balance of type I and type II errors, even under conditions where all other tests have extraordinarily high type I error rates or little power.

Animals↗
PubMed1999

Recognizing species diversity among large-bodied hominoids: a simulation test using missing data finite mixture analysis.

A persistent problem in paleoanthropology is the recognition of intra- vs. inter-specific differences within fossil samples. Exacerbating this situation is the often fragmentary nature of the fossils themselves, thus precluding rote applications of many multivariate approaches designed for complete case analyses. In this paper we apply finite mixture analysis to samples of large-bodied hominoids to test this procedure's efficacy in clustering individuals by species without a priori knowledge of group membership. In addition, we stochastically remove individual specimens and measurements, simulating small, incomplete fossil samples, and re-apply the finite mixture procedure to test how often it correctly assigns these "fragmentary" specimens. Finite mixture analysis can be highly accurate, even when confronted with small sample sizes and missing data. For example, a combination of 124 chimpanzees and humans are correctly identified in one analysis, and the accuracy drops only 2% to become 98% when the total sample size is reduced to 16 and missing data patterns are applied. In comparisons to better known methods that have been used to recognize groups in the fossil record, such as k-means, the benefits of finite mixture analysis are readily apparent. First, k-means is unable to accommodate missing data, an obvious deficiency when investigating the fossil record. Second, in direct comparisons of their ability to accurately assign "unknowns" to taxa, finite mixture performed at least as well as, and often better than, k-means in our analyses. A potential test that can be used to identify species in the fossil record, derived from comparisons of results generated from a general vs. a restricted (isometry-corrected) finite mixture analysis, is presented.

Animals↗
PubMed1999

Antigen sequence- and library-based mapping of linear and discontinuous protein-protein-interaction sites by spot synthesis.

The knowledge (antigen-derived peptide scans)- and library (de novo)-based mapping of linear and discontinuous antibody epitopes as well as protein-protein contact sites in general by spot synthesis now is a well established technique. Due to its automation, this technique also promises great potential for applications in functional genomics. It should help to elucidate the complex network of interacting protein molecules involved in signal transduction events (Adam-klages et al. 1996; Hoffmüller et al. 1999). Although little chemistry is involved in the preparation of peptide scans or libraries and the synthesis procedure is relatively simple, the laboratories of immunologists or molecular biologists are often not equipped to perform spot synthesis. In this case scans or libraries can be purchased from commercial suppliers.

Antigen-Antibody Reactions↗
PubMed1999

Antimicrobial efficacy of antiseptic mouthrinse solutions.

OBJECTIVE: To assess the activity of different mouthrinse solutions compared to sterile water and sage tea against aerobe bacteria in the oral cavity. METHODS: The extent and the duration of the salivary bacterial count reduction were determined using a uniform model that allows a direct comparison of the different products. In contrast to previous investigations the antimicrobial activity of the tested products was stopped by specific neutralizers immediately after sampling. RESULTS: The obtained results allowed us to classify four categories of mouthrinse solutions according to their antimicrobial properties: Products without any active antimicrobial effect (sterile water, sage tea, Fluomint-Lysoform), products with a weak and temporary effect that does not exceed a salivary bacterial count reduction of 1.5 log of colony forming units (cfu) immediately and 1.0 log cfu 1 h after application (hydrogen peroxide, Meridol, Listerine, Lavasept), products with a strong immediate effect (> or =1.5 log cfu) but no prolonged activity (Betaisodona solution, acriflavine) and finally products that exert a sustained effect of at least 1.0 log cfu 1 h after application (Chloramine T, Gurfix, Skinsept mucosa, Corsodyl, Dobendan, Octenisept). CONCLUSION: The method used in this investigation allows an easy and reproducible evaluation of antimicrobial efficacy and may be part of a future test guideline for efficacy testing of antiseptics.

Adult↗
PubMed1999

Activities of lysozyme and salivary peroxidase in unstimulated whole saliva in relation to plaque and gingivitis scores in healthy young males.

The purpose of the present investigation was to study the suitability of the salivary activity of lysozyme and salivary peroxidase for monitoring the inflammatory state of the gingiva. Salivary peroxidase and lysozyme activities in resting whole saliva were measured in a group of 140 male subjects (aged 18-30 years). A full mouth, clinical assessment of the plaque index (PI) and the sulcus bleeding index (SBI) was made and gingival crevicular fluid (GCF) flow was measured at teeth 16, 12, 24, 36, 32 and 44 with the Periotron 6000. There were no significant differences in the mean values of lysozyme and salivary peroxidase activities between groups with different PI, SBI and GCF flow values. Statistically significant correlations were found among the clinical parameters, with SBI and PI showing the strongest relation (r = 0.47). The correlation between GCF flow and PI was higher (r = 0.43) than the correlation between GCF flow and SBI (r = 0.20). However, there were no statistically significant correlations between the activities of salivary peroxide and lysozyme and the clinical measures of gingival health.

Adolescent↗
PubMed1999

Routine use of bilateral skeletonized internal mammary arteries for myocardial revascularization.

BACKGROUND: Complete arterial myocardial revascularization without the use of saphenous veins grafts was primarily performed on selected patient populations such as the young and nondiabetic. In a recently developed surgical technique, the internal mammary artery is dissected gently as a longer skeletonized artery, providing greater versatility for complete arterial revascularization, without saphenous veins grafts. METHODS: We prospectively evaluated the impact of the routine use of double skeletonized internal mammary artery in 472 patients who underwent coronary artery bypass grafting between April 1996 and June 1997. Their average age was 65 years (30 to 87 years), 383 (83%) were men, and 89 (17%) women. One hundred sixty-nine (36%) of the patients were older than 70 years, and 145 (31%) were diabetic. The average number of grafts was 3.2 per patient (two to six grafts). RESULTS: Operative mortality was 1.7% (n = 8). The mortality of urgent and elective patients was 0.7% (3 of 410 patients), and that of emergency operations was 8.1% (5 of 62 patients; p < 0.01). There were three (0.6%) perioperative infarcts, and 6 patients (1.3%) sustained strokes. Sternal wound infection occurred in 8 patients (1.7%). Postoperative follow-up (1 to 25 months) was available in 462 patients (99%). Two-year actuarial survival was 96.8%, and 92% of the surviving patients are well and free of angina. Neither diabetes mellitus nor old age (>70 years) were significant independent predictors of any early or late untoward events. None of the 70 diabetic patients more than 65 years of age developed sternal wound infection. Chronic lung disease was found to be the only independent predictor for sternal infections. CONCLUSIONS: Routine use of bilateral skeletonized internal mammary artery is a safe replacement for the current myocardial revascularization technique even in the old and diabetic patients.

Adult↗