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Biomedical subjects

B Kamm

Publications and source records attributed to B Kamm.

At least 19 recordsLinked to original sources
PubMed2006

Chemical and biochemical generation of carbohydrates from lignocellulose-feedstock (Lupinus nootkatensis)--quantification of glucose.

Different chemical and enzymatic methods were applied for the hydrolysis of main stems from Lupinus nootkatensis (harvest November 2002). The whole process (all steps) is based on the lignocellulose-feedstock biorefinery regime. The acid hydrolysis of L. was performed with concentrated hydrochloric acid; advantages in this process are exothermic hydrolysis and the possibility of acid recovery. Enzymatic hydrolysis achieved high yields of fermentable carbohydrates (regarding to input cellulose) with high selectivity. However, this way requires the generation of cellulose from L. by chemical pulping. Monosaccharide derivatives thus obtained were identified by their GC retention times and the corresponding MS fragmentation. Hexamethyldisilazane was used as derivatization reagent to prepare the trimethylsilyl derivatives of the carbohydrates and of the degradations products of cellulose from the different fractions. The glucose content was quantified by GC peak integration with respect to an internal standard.

Biomass↗
PubMed2004

Polycarnitine--a new biomaterial.

The natural product L-carnitine is--due to its biotechnological accessibility and specific properties--on the way to becoming an attractive biobased bulk product. L-carnitine is a natural betaine with vitamin properties. Carnitine is an essential part of the fatty acid metabolism of human beings and animals. Carnitine was first isolated in 1905 from meat extract and important recent developments include the biosyntheses of L-carnitine from L-lysine or gamma-butyrobetaine. Our synthesis routes are designed to maintain the primary structure and specific properties of carnitine, such as hydrophilicity and "stiffening" effects for polymeric structures and applications. L-carnitine is converted via lactonization or olefinization into polymerizable basic molecules. The properties and the applications of carnitine polymers are described.

Biotechnology↗
PubMed2004

Principles of biorefineries.

Sustainable economic growth requires safe, sustainable resources for industrial production. For the future re-arrangement of a substantial economy to biological raw materials, completely new approaches in research and development, production and economy are necessary. Biorefineries combine the necessary technologies between biological raw materials and industrial intermediates and final products. The principal goal in the development of biorefineries is defined by the following: (biomass) feedstock-mix + process-mix --> product-mix. Here, particularly the combination between biotechnological and chemical conversion of substances will play an important role. Currently the "whole-crop biorefinery", "green biorefinery" and "lignocellulose-feedstock biorefinery" systems are favored in research and development.

Bioelectric Energy Sources↗
PubMed2001

Separation, identification, and quantification of amino acids in L-lysine fermentation potato juices by gas chromatography-mass spectrometry.

The amino acid composition of L-lysine fermentation juices from potatoes and cane molasses from a green biorefinery has been determined by gas chromatography-mass spectrometry. N-Methyl-N-tert(butyldimethylsilyl)tri-fluoroacetamide (MTBSTFA) was used as derivatization reagent to prepare the t-butyldimethylsilyl derivatives of the amino acids present in the juices. The amino acids in these derivatives were identified from both their EI and CI mass spectra and their retention times in the gas chromatogram, and they were quantified employing the GC response signals relative to cycloleucine as internal standard.

Acetamides↗
PubMed2000

Qualitative and quantitative analysis of carbohydrates in green juices (wild mix grass and alfalfa) from a green biorefinery by gas chromatography/mass spectrometry.

Green juices from biorefinery original raw material (wild mix grass and alfalfa after wet fractionation and protein separation) have been investigated by gas chromatography/mass spectrometry. The carbohydrates, involved in the green juices, were derivatized and identified by both their retention times in the gas chromatogram and EI mass spectra compared to those of pure reference compounds. Additionally, chemical ionization mass spectra were recorded for better characterizing the carbohydrates present. The carbohydrates which could thus be identified, were quantified by response signals with respect to that of the internal standard beta-phenyl-D-glucopyranoside.

Biomass↗
PubMed1996

Pharmacokinetics of oral mycophenolate mofetil in volunteer subjects with varying degrees of hepatic oxidative impairment.

Eighteen patients with compensated alcoholic cirrhosis participated in a single-dose pharmacokinetic study of oral mycophenolate mofetil (MMF). Participants were divided into groups of 6 patients each with mild, moderate, or severe hepatic oxidative impairment as defined by the aminopyrine breath test (APBT). Clinically, hepatic disease was of mild or moderate severity. Six healthy volunteers were included as control subjects. Plasma and urine samples were collected over 96 hours and assayed for the active metabolite mycophenolic aced (MPA) and the glucuronide conjugate, MPAG. Plasma protein binding of MPA also was determined in 6 unrelated patients with cirrhosis. Cirrhosis did not grossly affect plasma pharmacokinetics or plasma binding of MPA. Maximum plasma concentrations (C(max)) and area under the curve (AUC) of MPA and MPAG consistently decreased, increased, and then decreased as oxidative impairment declined from normal to severe. Patients with cirrhosis had comparable or greater recovery of administered drug substance in urine than controls, showing that cirrhosis did not affect the extent of MMF absorption. Urine clearance of MPAG was two times higher in the group with severe impairment than in the other groups. Creatinine clearance was similar in all groups. These results suggest progressive impairment of hepatic glucuronidation of MPA and induction of renal glucuronidation in patients with severe hepatic oxidative impairment.

Administration, Oral↗
PubMed1992

Prevention of stroke with ticlopidine: who benefits most? TASS Baseline and Angiographic Data Subgroup.

We examined the baseline characteristics of patients in the Ticlopidine Aspirin Stroke Study (TASS) to determine if the effects of the two treatments in preventing stroke differed in various subgroups. Patients with the following characteristics did less well on aspirin: elevated creatinine, hypertension or diabetes requiring treatment, or treatment with anticoagulant or antiplatelet drugs prior to their qualifying TIA or stroke. Women and patients with vertebrobasilar symptoms did particularly well on ticlopidine. We performed arteriography in 1,188 patients with carotid qualifying events. The frequency of stroke in patients with abnormal arteriograms ipsilateral to their symptoms was slightly higher than in those with normal carotid arteries. Ticlopidine was more effective in patients without carotid stenosis. Ticlopidine is more effective than aspirin in preventing strokes in patients having warning TIAs. The patients who benefit most from ticlopidine may be women, those who have vertebrobasilar symptoms, those with cerebral ischemic symptoms while on aspirin or anticoagulant therapy, and patients with diffuse atherosclerotic disease rather than high-grade carotid stenosis.

Aspirin↗
PubMed1989

A randomized trial comparing ticlopidine hydrochloride with aspirin for the prevention of stroke in high-risk patients. Ticlopidine Aspirin Stroke Study Group.

We report the results of the Ticlopidine Aspirin Stroke Study, a blinded trial at 56 North American centers that compared the effects of ticlopidine hydrochloride (500 mg daily) with those of aspirin (1300 mg daily) on the risk of stroke or death. The medications were randomly assigned to 3069 patients with recent transient or mild persistent focal cerebral or retinal ischemia. Follow-up lasted for two to six years. The three-year event rate for nonfatal stroke or death from any cause was 17 percent for ticlopidine and 19 percent for aspirin--a 12 percent risk reduction (95 percent confidence interval, -2 to 26 percent) with ticlopidine (P = 0.048 for cumulative Kaplan-Meier estimates). The rates of fatal and nonfatal stroke at three years were 10 percent for ticlopidine and 13 percent for aspirin--a 21 percent risk reduction (95 percent confidence interval, 4 to 38 percent) with ticlopidine (P = 0.024 for cumulative Kaplan-Meier estimates). Ticlopidine was more effective than aspirin in both sexes. The adverse effects of aspirin included diarrhea (10 percent), rash (5.5 percent), peptic ulceration (3 percent), gastritis (2 percent), and gastrointestinal bleeding (1 percent). With ticlopidine, diarrhea (20 percent), skin rash (14 percent), and severe but reversible neutropenia (less than 1 percent) were noted. The mean increase in total cholesterol level was 9 percent with ticlopidine and 2 percent with aspirin (P less than 0.01). The ratios of high-density lipoprotein and low-density lipoprotein to total cholesterol were similar in both treatment groups. We conclude that ticlopidine was somewhat more effective than aspirin in preventing strokes in this population, although the risks of side effects were greater.

Aspirin↗
PubMed1987

Design features of a controlled clinical trial to assess the effect of a calcium entry blocker upon the progression of coronary artery disease.

This report presents the design and methodological features of a double-blind, randomized, placebo-controlled, trial in 383 patients with coronary artery disease. The study's principal objective is to determine whether chronic treatment with a calcium entry blocker can retard the progression of coronary artery disease. The study population consists of patients with coronary artery disease and a baseline coronary arteriogram that qualifies them as being at high risk for disease progression. After satisfying all entry criteria, patients were randomized to receive either the calcium entry blocker nicardipine or placebo. All indicated concomitant medications except calcium entry blockers are permitted. Patients are being followed clinically for 24 months before undergoing a second coronary arteriogram. The effect of the treatments on a variety of clinical and angiographic parameters will be determined.

Adult↗
PubMed1982

Relationship of serum naproxen concentration to efficacy in rheumatoid arthritis.

Twenty-four patients with rheumatoid arthritis were tested in a randomized, double-blind. Latin-square comparison of 250, 750 and 1500 mg of naproxen daily. Each received each dose for 2 wk and baseline disease activity was established during withdrawal of medication before and after the study. Nine standard measures of efficacy were tested at each evaluation. No order effect or change in baseline was found. Total and unbound naproxen concentrations were measured by high-pressure liquid chromatography and equilibrium dialysis, respectively. A linear dose-response relationship (P less than 0.05) was demonstrated between naproxen and joint count, patient's pain assessment, activities of daily living index, physician's global assessment, and grip strength. The relationship to patients' global assessment was of uncertain significance (P less than 0.07). A positive dose to serum level correlation (1, 2, and 12 hr after dose) was apparent (r greater than 0.78). When patients were defined as responders or nonresponders by a summed efficacy score, there was a serum concentration-response relationship; the percentage of responding patients increased with each serum level quartile: 25%, 31%, 59%, and 75%. Patients with a trough total serum naproxen concentration under 18 micrograms/ml did not respond, while 76% of patients with trough total serum concentrations above 50 micrograms/ml responded. No serum naproxen toxicity level relationship was established.

Adult↗
PubMed1979

Spirometry in amyotrophic lateral sclerosis.

Clinical evaluation and pulmonary function tests were performed in 218 patients with motor neuron disease, mainly amyotrophic lateral sclerosis (ALS). Serial studies were obtained in 103 patients, in 31 until death from ALS. Most patients, regardless of the pattern of motor neuron involvement, had characteristic abnormalities in pulmonary function, including reduced forced vital capacity (FVC) and maximum voluntary ventilation (MVV). Reductions in the FVC and MVV to as low as 50% were commonly missed by clinical evaluators. Spirometry is therefore of value in detecting early involvement of respiratory neurons. Progressively greater reductions in the FVC and MVV in all the fatal cases indicate that serial spirometry has prognostic value in ALS.

Adult↗
PubMed1979

Use of treadmill score to quantify ischemic response and predict extent of coronary disease.

In this study we assessed whether various responses to exercise testing could be quantified in order to derive the probabilities of presence of coronary disease, and if present, to assess its severity. A treadmill score based on the exercise response was determined in 405 patients who had both treadmill tests and coronary angiograms. The score was derived using discriminant function analysis, by weighting and combining depth and configuration of ST depression (downsloping, horizontal or slowly upsloping), timing onset and duration of ischemia, grading ventricular arrhythmias, heart rate and blood pressure change, coexistence of exercise-induced chest pain and sex. The treadmill score was effective in detecting coronary disease (lesions with an greater than or equal to 50% narrowing), with a predictive accuracy (PA) (probability that a subject manifesting a positive test has disease) of 87%, a true negative rate (TNR) (probability of a subject with a negative test having no disease) of 80%, and sensitivity of 94%. The treadmill score also detected severe disease (triple-vessel, main left and/or greater than 90% proximal occlusion of the left anterior descending artery), with a PA of 73%, TNR of 79% and sensitivity of 82%. We conclude that the exercise response, expressed numerically as a treadmill score, permits analysis of most of the relevant data from exercise testing, increases test accuracy by 10-15% compared with standard criteria for treatmill test interpretation, and enables the derivation of probability statements for presence and severity of coronary disease. The validity of any prediction on the basis of exercise performance may thus be quantitatively judged.

Analysis of Variance↗
PubMed1978

Thromboembolic complications after mitral valve replacement with Hancock xenograft.

Case histories of 140 patients who had mitral valve replacement with the Hancock xenograft were reviewed according to the incidence of thromboembolic complications. There were 16 patients with preoperative and/or postoperative low-output syndrome (Group A.) Eight of these patients died, and six had autopsies which showed major thrombi on the heterograft valve. In 126 long-term survivors (followed 1 to 33 months) nine thromboembolic events occurred (thromboembolic incidence 5.3 percent per patient-year). All patients with emboli were in atrial fibrillation. Additional predisposing factors included a history of systemic emboli and the presence of atrial clots at the time of surgery. The majority (7/9) of emboli occurred during the first 3 postoperative months. Two emboli occurred immediately following the operation (before oral anticoagulation therapy could have been begun). Five occurred in patients who were not on anticoagulation (Group B) and two occurred under warfarin treatment (Group C). There was no thromboembolic event in patients taking aspirin (Group D). It is concluded that hemodynamically stable patients have a decreased risk of thromboembolism and do not require anticoagulation. Patients with atrial fibrillation have an increased thromboembolic risk and should be on a regimen of warfarin for 3 months postoperatively and then on aspirin therapy.

Adolescent↗