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Biomedical subjects

K Schmidt

Publications and source records attributed to K Schmidt.

At least 199 records · Page 11Linked to original sources
PubMed1997

Release of nitric oxide from donors with known half-life: a mathematical model for calculating nitric oxide concentrations in aerobic solutions.

The NO concentrations released from donor compounds are difficult to predict as they are determined by formation and inactivation reactions. To calculate the concentrations of NO over time, we have developed a mathematical model which is based on a system of two differential equations describing the first order decomposition of the NO donor in association with the third order reaction of NO with oxygen. Although there is no closed formula for the solution, it can be easily computed by any standard numerical differential solver or simulation software with the following input parameters: initial concentration and decomposition rate constant of the NO donor, O2 concentration, and rate constant for NO autoxidation. The model was validated by monitoring NO release from 2,2-diethyl-1-nitroso-oxyhydrazine (DEA/NO) with a Clark-type NO-sensitive electrode at two different temperatures (25 and 37 degrees C) and DEA/NO concentrations ranging from 1 to 10 microM. Under all conditions, there was an excellent agreement between experimental and calculated data. In addition to the computer modeling, we present graphical plots which allow a rough but very easy estimation of the actual NO concentrations if appropriate computer software should not be available.

Kinetics↗
PubMed1997

[Modification of proprioceptive ability of knee joints with primary gonarthrosis].

In the study presented, knee joint proprioception of 17 patients with primary degenerative joint disease of the knee joint was evaluated. As a control group, the proprioception of 30 healthy volunteers with clinical and anamnestically inconspicuous knee joints was examined. We tested the proprioceptive capability of the subjects with an angle reproduction test. Additionally, all knee joints were measured with and without an elastic knee bandage. The study showed significantly more deterioration in knee joint proprioception in patients with gonarthrosis than in the control group. Even the proprioception of the contralateral, healthy knee joint was worse than the results of the control group. However, after using an elastic knee bandage, significant improvement in the proprioceptive abilities of the injured knee joint was documented.

Adult↗
PubMed1997

[Proprioceptive capacities of patients with retropatellar knee pain with special reference to effectiveness of an elastic knee bandage].

In the presented study, knee joint proprioception of 43 patients with a patellar pain syndrome of the knee joint was evaluated. In a control group, the proprioception of 30 healthy volunteers with clinical and an-amnestic inconspicous knee joints was examined. We tested the proprioceptive capability of the subjects with a passive angle reproduction test. Additionally, all knee joints were measured with and without an elastic knee bandage. The patient group showed significant deterioration of angle reproduction capability (13.2 degrees +/- 6.1 degrees) compared to the control group (7.8 degrees +/- 2.8 degrees). After applying an elastic knee bandage, the angle reproduction capability significantly improved to 9.2 degrees +/- 4.5 degrees. Proprioception of the contralateral, noninvolved knee joint in the patients (11.6 degrees +/- 6.3 degrees) was worse compared to the control group. Applying an elastic knee bandage did not significantly improve the proprioception of the uninjured knee joint.

Adult↗
PubMed1997

[Primary results and long-term outcome of an ambulatory, cardiac rehabilitation model (phase II) after myocardial infarct, dilatation treatment and heart operation].

From October 1994 to July 1996, 128 patients (30 women, 98 men) participated in an outpatient cardiac rehabilitation program (phase II). Our objectives were to demonstrate risk-factor modification and increased work-load capacity resulting directly from the rehabilitation in terms of primary results and long-term effects, 6 months (n = 59) and 12 months (n = 30) after termination of the program. We observed how many of the patients were able to be occupationally re-integrated after completion of phase II rehabilitation. During the 4-week program, the work-load capacity increased significantly from 1.2 W/kg to 1.5 W/kg (p < or = 0.05). After 6 months (1.4 W/kg) and 1 year (1.5 W/kg), consistently high workload capacities were noted. Total cholesterol decreased significantly from 247 mg/dl to 201 mg/dl (p < or = 0.05) during the 4-week program. After 6 months (219 mg/dl) and 1 year (210 mg/dl) significant reductions persisted (p < or = 0.05). Similar results with LDL-cholesterol were seen: 185 mg/dl before entering the program, 146 mg/dl after 4 weeks, 158 mg/dl after 6 months and 151 mg/dl after 1 year. Triglyceride levels showed a significant reduction (p < or = 0.05), 189 mg/dl before entering in the program, 148 mg/dl after 4 weeks, 143 mg/dl after 6 months, and 135 mg/dl after 1 year. The HDL-levels increased slightly as a long-term effect, i.e., from 51 mg/dl to 49 mg/dl during the 4 week program, and 57 mg/dl after 6 and 12 months. Of the patients questioned (n = 73), 73% found the program very good, 27% said it was good, and no patient was dissatisfied. Of the 63 patients who were actively employed before becoming ill and later entered our program, 51 (81%) were able to be immediately re-integrated into their previous occupation. In several cases this re-integration took 7 weeks. Seven (11%) patients applied for pension, and 5 (8%) patients remained unemployed on sick-leave.

Adult↗
PubMed1997

[Therapy of rheumatoid destruction of the middle finger metacarpophalangeal joint with a Swanson silastic implant stabilized resection arthroplasty: comparative study of long and intermediate term results with and without implantation of titanium grommets].

Resection arthroplasty of the metacarpophangeal joints stabilized by a Swanson-Silastic-spacer is the golden standard in MP-joint destruction in R.A. 57 (Gr. I), 91 (Gr. II), and 102 (Gr. III) arthroplasties of the metacarpophalangeal joint were assessed in three groups of patients 3.5 years (Gr. I), 4.3 years (Gr. II), and 10.1 years (Gr. III), respectively, postoperatively on the average. In patients of group I titanium protectors, called grommets, were used additionally. Nearly all patients reported a marked relief of pain. Ulnar drift was corrected from an average of 22 degrees (Gr. I), 23 degrees (Gr. II), and 34 degrees (Gr. III) preoperatively. to 8 degrees (Gr. I), 7 degrees (Gr. II), and 12 degrees (Gr. III), respectively, postoperatively. Active range of motion remains unchanged with an average of 33 degrees (Gr. I), 38 degrees (Gr. II), and 42 degrees (Gr. III) ROM preoperatively and 42 degrees (Gr. I), 37 degrees (Gr. II), and 36 degrees (Gr. III) ROM, respectively, postoperatively. The average extension deficit had improved from 45 degrees (Gr. I), 32 degrees (Gr. II), and 33 degrees (Gr. III) at surgery to 18 degrees (Gr. I), 11 degrees (Gr. II), and 11 degrees (Gr. III), respectively, at the time of follow-up. Functional improvement of the hand was found in the medium term in 82% and in the longterm in 75% of the patients. The radiographical findings showed surrounding osteolysis in 45.7% (Gr. I), 63.5% (Gr. II), and 89.4% (Gr. III) of the implants and 0% (Gr. I), 16.5% (Gr. II), and 26.9% (Gr. III) broken spacers. From the medium to the longterm run there is an increase in radiographical deterioration. The additional use of titanium grommets in MP-joint arthroplasty seems to reduce reactive osteolysis and protects Swanson Silastic-spacers from breakage without substantial influence on the clinical outcome.

Arthritis, Rheumatoid↗
PubMed1997

External stabilization of long-segment tracheobronchomalacia guided by intraoperative bronchoscopy.

BACKGROUND: Symptomatic obstruction of long-segment tracheal or bronchial portions either related to congenital instability or secondary to vascular compression are rare malformations, which remain difficult to manage. A method of external tracheal or bronchial stabilization is described. METHODS: From July 1992 to April 1995, 7 children (age range, 4 months to 4 years; mean age, 19 months) and 1 adult (age, 46 years) were operated on for severe respiratory insufficiency. In 4 cases of congenital tracheal instability, 2 children had associated type IIIb esophageal atresia. Both children with esophageal atresia had previous operations (two and three times, respectively): 1 child had aortopexy and division of a patent ductus arteriosus and another child had distal tracheal resection elsewhere, both without relief of malacia. All children were intubated and ventilated since birth for 11 to 15 months. Secondary tracheobronchomalacia due to vascular compression was seen in 4 patients caused by double aortic arch (n = 2) and persisting ligamentum arteriosum after previous ligation of a patent ductus arteriosus (n = 2), with 1 child ventilated thereafter for 5 months. Operation was performed with the aid of extracorporeal circulation in all patients but 1, and consisted of transection of vascular rings and persistent ligamentum Botalli (n = 5), closure of multiple ventricular septal defects (n = 1) and extensive mobilization of the tracheobronchial tree as well as the great arteries. External stabilization of the severely dysplastic distal trachea (n = 6) or left main bronchus (n = 2) was achieved by suspending the malacic segment within an oversized and longitudinally opened ring-reinforced polytetrafluoroethylene prosthesis. Multiple plegeted sutures were placed extramucosally to the dysplastic tracheal wall and the dyskinetic pars membranacea, as well as to the polytetrafluoroethylene prosthesis in a radial orientation. Guided by simultaneous video-assisted bronchoscopy, reexpansion of the collapsed segments was achieved by gentle traction on the sutures while tying. RESULTS: Stenosis-free tracheobronchial reexpansion was achieved in all patients, as seen on repeated bronchoscopies during hospitalization and thereafter. All patients were extubated within 1 to 12 days after the operation. There was one late death, unrelated to the procedure, in a 31-month-old child 20 months after the operation. All other patients are free of stridor and in excellent clinical condition 21 to 54 months (mean, 38 months) thereafter. CONCLUSIONS: The presented method of bronchoscopically guided external tracheobronchial suspension within a ring-reinforced polytetrafluoroethylene prosthesis immediately relieves severe malacia of the trachea or main bronchi in infants as well as adults without necessitating resection. Midterm preliminary data suggest that growth potential of the affected segment exists within the oversized polytetrafluoroethylene prosthesis.

Abnormalities, Multiple↗
PubMed1997

Quantification of replication of clinical cytomegalovirus isolates in cultured endothelial cells and fibroblasts by a focus expansion assay.

A method for quantitative analysis of the growth properties of human cytomegalovirus (HCMV) in various cell culture systems was developed. Recent HCMV isolates are, in most cases cell associated, causing only limited cytopathic effect. This renders comparative analysis of the biological properties of such isolates difficult. The focus expansion assay described in this study is based on cocultivation of infected fibroblasts with a cell type of choice, relying on cell mediated infectivity. The extent of replication of a given isolate in cell culture is quantified by determining the size of resulting infectious foci. Analysis of various clinical isolates and laboratory strains indicated that this assay is a reliable and valid method to define growth properties of HCMV in cell culture. Remarkable differences in the cytopathogenicity of these isolates in fibroblasts as well as in endothelial cells were found. The assay will be useful in studies regarding cell tropism and virulence of recent HCMV isolates and for the quick and easy phenotypic characterization of HCMV deletion mutants.

Antigens, Viral↗
PubMed1997

GABA(A) receptor activation triggers a Cl- conductance increase and a K+ channel blockade in cerebellar granule cells.

GABA(A) receptor activation in cerebellar granule cells induced a complex physiological response, namely the activation of a Cl- conductance in concert with a blockade of the resting K+ outward conductance (by 71% as compared to controls). Both responses were mediated by the activation of GABA(A) receptors, since they were both mimicked by the GABA(A) receptor agonist muscimol and antagonized by picrotoxin and bicuculline. A substantial decrease of the mean open time of single, outwardly rectifying K+ channels was triggered by GABA as revealed from cell-attached recordings; this finding implies that an intracellular pathway links GABA(A) receptors and K+ channels. Furthermore, this action of GABA is mediated through the cytoplasm, as experiments with the cell-attached patch-clamp technique show. GABA induced a prominent membrane depolarization ranging from 10 to 25 mV as revealed by current-clamp recordings of gramicidin (or nystatin) permeabilized patches, thus selecting conditions not to perturb the physiological Cl- gradient across the cell. Our findings imply that the GABA-activated Cl- current depolarized the membrane as described for immature neurons. The blockade of the resting K+ channel conductance acts in concert and both mechanisms lead to this substantial depolarizing event.

Animals↗
PubMed1997

Determining research priorities in pediatric nursing: a Delphi study.

A two-round Delphi study was performed in Pediatric Nursing at a large midwestern teaching hospital. The purpose of the study was to identify research priorities for the Pediatric Research committee for future projects. The initial survey was sent to all pediatric nursing staff. Sixty-two staff (19%) responded to the first round. Forty-five separate research topics/themes of interest were identified. The second round survey was sent to the 62 staff who responded to Round 1. Forty-eight staff (76%) responded. Participants were given a list of the 45 topics identified in Round 1, and asked to identify their top five priorities. Results were analyzed by unit and by Division. The identified priorities for the Division are described here.

Clinical Nursing Research↗
PubMed1997

Interference of carboxy-PTIO with nitric oxide- and peroxynitrite-mediated reactions.

Carboxy-PTIO reacts rapidly with NO to yield NO2 and has been used as a scavenger to test the importance of nitric oxide (NO) in various physiological conditions. This study investigated the effects of carboxy-PTIO on several NO- and peroxynitrite-mediated reactions. The scavenger potently inhibited NO-induced accumulation of cGMP in endothelial cells but potentiated the effect of the putative peroxynitrite donor SIN-1, Carboxy-PTIO completely inhibited peroxynitrite-induced formation of 3-nitrotyrosine from free tyrosine (EC50 = 36 +/- 5 microM) as well as nitration of bovine serum albumin. Peroxynitrite-mediated nitrosation of GSH was stimulated by the drug with an EC50 of 0.12 +/- 0.03 mM, whereas S-nitrosation induced by the NO donor DEA/NO (0.1 mM) was inhibited by the scavenger with an IC50 of 0.11 +/- 0.03 mM. Oxidation of NO with carboxy-PTIO resulted in formation of nitrite without concomitant production of nitrate. Our results demonstrate that the effects of carboxy-PTIO are diverse and question its claimed specificity as NO scavenger.

Animals↗
PubMed1997

Imbalance between the endothelial cell-derived contracting factors prostacyclin and angiotensin II and nitric oxide/cyclic GMP in human primary varicosis.

1. The role of the endothelium in the vasomotor control of human veins in the lower extremity is little understood. We tested the hypothesis that the production of relaxing and contracting factors is altered in endothelial cells from varicose saphenous veins which may predispose to the decreased vessel tone observed in primary varicosis. 2. We determined the intracellular accumulation of guanosine 3':5'-cyclic monophosphate cyclic GMP; a measure of nitric oxide production and the release of endothelin and prostacyclin (measured as its stable metabolite 6-keto-prostaglandin F1alpha) from cultured cells derived from the long saphenous veins of patients with primary varicosis (Varicose saphena group, n = 27) or from patients undergoing coronary artery bypass surgery (Healthy saphena group, n = 22). In addition, levels of endothelin, angiotensin II, bradykinin, cyclic GMP and cyclic AMP in plasma from patients with primary varicosis and healthy volunteers (n = 8-11 in each group) were determined. 3. Although basal cyclic GMP levels were similar, more cyclic GMP accumulated in response to histamine (1-100 micromol l[-1]) in cells from varicose saphenous veins (0.75 +/- 0.1 pmol per well) than in cells from veins without varicosis (0.27 +/- 0.05 pmol per well). Furthermore, the relaxant potency of nitroprusside (1 nmol l(-1) - 300 micromol l[-1]) in vitro was higher for varicose veins (mean EC50 = 5.9 micromol l(-1); n = 8) than healthy veins (mean EC50 = 20.0 micromol l(-1); n = 7). 4. The production of prostacyclin was significantly less in cells from varicose than healthy saphenous veins (66 +/- 8.7 and 121 +/- 20.1 nmol g(-1) protein), but the production of endothelin was similar in both groups. Prostacyclin (3 nmol l(-1) 30 micromol l[-1]) consistently contracted rings of varicose saphenous vein in vitro with a mean EC50 value of 10-20 micromol l(-1) (n = 7); the maximum tension generated was approximately 50% of that of a completely depolarizing solution of K+ (120 mmol l[-1]). 5. In plasma from patients with varicose veins, levels of cyclic GMP were higher than in healthy controls (9.2 +/- 0.03 and 7.2 +/- 0.02 nmol l[-1]), levels of angiotensin II were lower (81 +/- 11.5 and 147 +/- 21.7 pmol l[-1]), and levels of endothelin, cyclic AMP, and bradykinin were not different. 6. It is concluded that endothelial cells from diseased saphenous veins secrete less constrictor mediators than cells from healthy veins and that in diseased veins the nitric oxide/cyclic GMP system is up-regulated which may shift the balance of vasoactive factors towards vasodilatation and contribute to the development of primary varicosis.

Adult↗
PubMed1997

Superiority of carbohydrate-deficient transferrin to gamma-glutamyltransferase in detecting relapse in alcoholism.

OBJECTIVE: The usefulness of carbohydrate-deficient transferrin is widely accepted in screening (male) population samples for heavy alcohol consumption, but its role in relapse detection is not convincingly established. The authors therefore compared the diagnostic value of carbohydrate-deficient transferrin with the commonly used gamma-glutamyltransferase in identifying relapsed alcoholics during outpatient aftercare. METHOD: The patients were 101 male alcoholics who entered a 6-month rehabilitation program after hospital detoxification. Drinking status was assessed by means of self- and collateral reports obtained during regular contacts with the rehabilitation team; relapse was defined as consumption of any alcohol. Visits occurred weekly during month 1, biweekly during month 2, and every 4 weeks during months 3-6. At every visit a blood sample was taken for measurement of carbohydrate-deficient transferrin and gamma-glutamyltransferase. RESULTS: The proportion of men who reported relapse was 25.6% per scheduled contact on average. Positive predictive values indicated that relapse was identified with a 76.2% probability by carbohydrate-deficient transferrin values above the upper normal limit, in contrast to a 32.9% chance with gamma-glutamyltransferase. Carbohydrate-deficient transferrin was especially useful in detecting early relapses during the initial rehabilitation phase, when gamma-glutamyltransferase values had not normalized. Because of the longer half-life of gamma-glutamyltransferase, it had some value with a 4-week monitoring schedule in detecting new drinking episodes in alcoholics whose previous results had been normal. CONCLUSIONS: Carbohydrate-deficient transferrin proved to be superior to gamma-glutamyltransferase in relapse detection in an outpatient care setting for alcoholics.

Adult↗
PubMed1997

[Importance of nutritional aspects in attention deficit hyperactivity disorders].

The attention deficit hyperactivity disorder is a common childhood syndrome that is recognized as an important medical-social problem, being the object of an exhaustive investigation related to its etiology, diagnostic approach and prevention, and treatment forms. Among the factors that can alter the cerebral function, is the malnutrition. The authors discuss the association of the syndrome with the nutritional condition of students from elementary schools.

Analysis of Variance↗
PubMed1997

[Deterministic-chaotic and spectral-functional analysis of heart rate and respiratory movements].

After an introduction into the analysis of periodical-linear and deterministic- chaotic characteristics of heart rate fluctuations and respiratory movements their physiological background and clinical aspects are debated. Using the example of own results at the mature rabbit and new-born pig different relations of periodical-linear and deterministic-chaotic characteristics in dependence on the experimental status and neurovegetative blockades are demonstrated. From the data assignments of these characteristics are derived.

Animals↗
PubMed1997

[Prejudice and judgment: psychiatric consultation from the viewpoint of the patient].

187 general hospital patients were questioned in a prospective study with a semistructured interview about their subjective experience and assessment of the psychiatric consultation. Over 40% complained that they had been given insufficient information about the psychiatric consultation by their primary care physician. It was rarely (10%) found to be unpleasant, and 46% of the patients specifically stated that it had been valuable. In order to improve the efficiency of the psychiatric consultation more attention should be paid to the subjective judgement of the patients.

Adolescent↗
PubMed1997

Interaction of antioxidative micronutrients with host defense mechanisms. A critical review.

An adequate host defense activity critically depends upon the micronutrient status of an individual among which the cellular oxidant-antioxidant balance is an important determinant. Oxidative burst is part of the physiological function of phagocytes connected to a massive production and release of reactive oxygen intermediates. At the same time, maintenance of the functional capacity of the host defense system in fighting against microorganisms and foreign antigens is significantly affected by the various reactive oxygen species. In order to compensate for this critical condition phagocytes do show active uptake and physiologically high intracellular concentrations of antioxidants. Thus, optimal function of the host defense system depends upon an adequate supply of antioxidative micronutrients and, on the other hand, impaired host defense activity can act as a very early and sensitive marker of marginal deficiency of antioxidant micronutrients. Assessment of immune functions can serve as an important preventative diagnostic tool in the detection of marginal but functionally relevant micronutrient deficiencies. Intervention into the functionally deficient antioxidant micronutrient status can act as the appropriate preventative or therapeutic treatment with higher efficacy and less adverse effects than direct pharmacological modulation of single immune functions by specific mediators.

Antioxidants↗