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Biomedical subjects

T Schubert

Publications and source records attributed to T Schubert.

At least 37 records · Page 2Linked to original sources
PubMed1996

[Analysis of interference effects in simultaneous processing of 2 problems].

The aim of this investigation was to analyze dual-task interference in the so called Psychological Refractory Period (PRP) paradigm. In this paradigm subjects have to carry out two choice reaction tasks that overlap in time. A well known result is that reaction time on task 2 (Rt2) increases with decreasing overlap of the two tasks. Thereby reaction time on task 1 is described to be independent of the size of overlap (Rt 1). Usually, this result is explained by the assumption of a PRP which arises in processing of task 2, when serial processing is ongoing in both tasks. It was asked, 1.) whether the PRP is located before or after response selection in the first task and 2.) how the second task influences first task processing. In the experiment subjects had to carry out two choice reaction tasks together. In different conditions the difficulty of response selection in task 2 was systematically increased by varying the number of response alternatives (0, 1, 2, 3). Difficulty of response selection in task 1 was held constant. Overlap between both tasks was varied. This experimental design allows different hypotheses about the sources of interference in both tasks to be examined by use of Schweickert's Critical Path Technique (Schweickert, 1983). Contrary to the results of Karlin and Kestenbaum (1968) the effects of number of response alternatives and size of overlap on Rt2 indicate a localization of the PRP before response selection. The results support models which assume a serial processing in response selection (Welford, 1952). They are contrary to models of parallel processing in this stage (Keele, 1973). The influence of the number of alternatives in task 2 on Rt 1 can be explained by a mechanism of grouping both motor responses.

Adolescent↗
PubMed1995

[13C]urea breath test to confirm eradication of Helicobacter pylori.

OBJECTIVE: To determine the utility of the [13C]urea breath test in confirming the eradication of Helicobacter pylori. METHODS: We reviewed our H. pylori database for patients who underwent [13C]urea breath test at baseline and 6 wk after triple therapy with tetracycline, metronidazole, and bismuth subsalicylate. Baseline infection was defined by the identification of the organism on antral biopsies or a reactive CLO test. Eradication was defined as a negative Warthin-Starry stain and a non-reactive CLO test at 24 h. All patients had a positive baseline [13C]urea breath test defined as [13C] enrichment > 6% at 60 min. RESULTS: One hundred eighteen H. pylori-infected patients (mean age 58.3 +/- 13.9 yr) met the review criteria (61 duodenal ulcers, 24 gastric ulcers, 33 non-ulcer dyspepsia). In 101/118 patients (86%), H. pylori was successfully eradicated (mean baseline breath test value 25.8 +/- 1.6). Of 101 patients, 95 had a negative 6-wk follow-up breath test (mean 2.2 +/- 0.2, p < 0.001). Of the 6/101 patients in whom treatment was successful, and who remained breath test positive at 6 wk, 4/6 were breath test negative when retested at 3 months. The remaining two patients were lost to follow-up. In 17/118 (14%) patients, H. pylori failed to be eradicated (mean baseline breath test 22.4 +/- 3.6). Fifteen of 17 patients had a positive breath test at 6 wk (mean 19.9 +/- 3.7). Two of 17 with a negative breath test at 6 wk tested positive when the breath test was repeated at 3 months. The sensitivity and specificity of [13C]urea breath test at 6 wk posttreatment are 97% and 71%, respectively. The positive and negative predictive values are 94% and 88%, respectively. CONCLUSIONS: [13C]urea breath test is a sensitive indicator of H. pylori eradication 6 wk after treatment. Antral biopsies are unnecessary to confirm eradication of H. pylori after completion of treatment.

Adult↗
PubMed1993

Pigmented villonodular synovitis in children. A case report.

Pigmented villonodular synovitis (PVS) is a rare disease of the synovial layer in joints, seen particularly in children. Early diagnosis allows treatment with resection of the affected synovial tissue, avoiding secondary osteoarthritic lesions of the normally unaffected joint structures. In this article, symptoms, clinical findings, and the diagnosis procedure are reported in a rare case of diffuse PVS in an 11-year-old girl. Diagnostic procedures are of differing value, and it seems that the most important factor is suspicion of this disease even in children. Since preoperative verification of the histological diagnosis is impossible, early invasive investigation such as arthroscopy are recommended to confirm the histological character of the lesion. Arthrotomy or arthroscopy followed by total synovectomy is recommended as the surgical treatment of first choice. Our patient was treated by total synovectomy via an arthrotomy of the affected knee joint after histological diagnosis has been confirmed by arthroscopic excision and histological analysis. Follow-up examinations 4 and 6 months postoperatively revealed no signs of recurrence.

Child↗
PubMed1993

Role of Helicobacter pylori serology in evaluating treatment success.

Duodenal ulcer recurrence and gastritis are reduced with successful Helicobacter pylori treatment. Serology is accurate in the diagnosis of H. pylori, but its value in determining eradication is unproved. To evaluate the usefulness of serology in monitoring treatment, we measured serial serum antibodies in three patient groups: eradication success (N = 57), eradication failure (N = 19), and untreated patients (N = 24). Eradication was determined by Warthin Starry staining of antral biopsies and repeat 13C breath tests at six weeks. Subsequent 13C breath tests were then performed at three-month intervals to monitor eradication. IgG antibody concentrations to H. pylori were determined by a commercially available ELISA kit. Serology concentrations remained constant throughout the study period in the untreated patients. IgG concentrations decreased slightly in the treatment failure group at six weeks but thereafter remained at baseline values. In the eradicated group, serum IgG concentrations decreased 26% by three months, 43% by six months and 55% at nine and 12 months (P < 0.001). A 20% reduction in IgG concentrations by six months was associated with successful treatment (sensitivity 86% and specificity 88%). We conclude that serology is a potentially useful way to monitor H. pylori treatment success.

Adult↗
PubMed1993

[Results of surgical therapy of bacterial sacroiliitis with primary arthrodesis].

Surgical treatment of pyogenic infections of the sacroiliac joint is indicated in cases of ineffective conservative treatment, abscess formation, septicemia, and neurological deficits. Between 1983 and 1990 in nine patients surgical treatment was performed for pyogenic sacroiliitis under this criteria. The surgical procedure included joint debridement, primary arthrodesis of the sacroiliac joint using a autologous bone graft, antibiotic therapy and postoperative immobilisation. Follow-up examination of 8 patients in average 47 months postoperatively revealed excellent functional and roentgenological results in 6 patients. Two patients suffered only from mild low-back pain, none of the eight patients demonstrated signs of a recurrent infection, one patient died due to complications of a long-lasting preoperative septicemia. Regarding these postoperative follow-up results surgical therapy including primary sacroiliac arthrodesis should be early considered, because this treatment has a low complication rate and the surgical technique is easy to perform and results are excellent or good in most of the patients.

Abscess↗
PubMed1993

Effects of single and repeated clonidine administration on the properties of central and peripheral alpha 2-adrenoceptors in man.

The centrally acting alpha 2-adrenoceptor agonist clonidine was used to assess the sensitivity of alpha 2-adrenergic neurotransmission in man, using receptor-binding studies and clonidine-induced growth hormone response. Neither acute (2 micrograms/kg body weight) nor subchronic (3 days, 2 x 150 micrograms/kg body weight) administration of clonidine affected platelet alpha 2-adrenoceptor number in humans as judged by 3H-yohimbine and 3H-UK-14,304 binding. The same treatment also did not modify central postsynaptic alpha 2-adrenoceptor function in the same individuals as assessed by clonidine-induced growth hormone responses. Similarly, subchronic (3 days, 500 micrograms/kg body weight, i.p.) or chronic (14 days, 500 micrograms/kg, i.p.) administration of clonidine to mice failed to change 3H-yohimbine or 3H-UK-14,304 binding sites in membranes prepared from frontal cortex. On the other hand, in vitro experiments using mouse frontal cortex or human platelet membranes showed pronounced reduction of 3H-UK-14,304 but not of 3H-yohimbine binding sites after incubation with several adrenoceptor agonists. The data indicate that acute and subchronic clonidine treatment may not change alpha 2-adrenoceptor sensitivity in humans or mice as assessed both at the functional and receptor level.

Adaptation, Physiological↗
PubMed1991

Levoprotiline ((-)-oxaprotiline) effects on inositol phosphate generation in human peripheral lymphocytes.

The effects of the atypical antidepressant levoprotiline (LPT) on inositol phosphate metabolism were investigated in N-formyl-methionyl-leucylphenylalanine (fMLP) activated human lymphocytes. In the presence of LPT, stimulation of phosphoinositide hydrolysis by fMLP lead to an increased accumulation of inositol bisphosphates, an effect which could be detected within the range of therapuetic plasma concentrations and which is exerted by lithium in a similar way. Furthermore, incubation of lymphocytes with LPT and subsequent stimulation with fMLP lead to a pronounced decrease in the level of free intracellular [3H]inositol. Both LPT effects, the increased accumulation of inositol bisphosphates and the reduction of free intracellular [3H]inositol, were found to be more pronounced for LPT than for its enantiomer (+)-oxaprotiline. The results are discussed in view of a possible biochemical mechanism which may contribute to the antidepressive activity of LPT.

Antidepressive Agents↗
PubMed1991

Therapeutic concentrations of lithium and carbamazepine inhibit cGMP accumulation in human lymphocytes. A clinical model for a possible common mechanism of action?

Although a large variety of biochemical effects have been reported for lithium (Li) and carbamazepine (Cbm), the final molecular mechanism underlying their therapeutic efficacy for recurrent affective disorders is still unknown. The data presented here clearly indicate that therapeutic concentrations of both drugs inhibit sodium nitroprusside-induced accumulation of cGMP in human lymphocytes to about the same extent. The effect is not seen for other antidepressants, and shows pronounced interindividual variations in healthy volunteers. A similar effect of lithium and carbamazepine can also be demonstrated for the cGMP accumulation of central neurons using the model of dissociated cells of the mouse brain. The results are discussed in view of a common mechanism of action of both drugs. Furthermore, it is speculated that the individual sensitivity of the cGMP generating system of human lymphocytes to both drugs might be used to predict therapeutic response or nonresponse of the individual patient.

Animals↗
PubMed1991

[Modification of tear film break-up time by beta blocker eyedrops without preservatives].

Traditional beta-blocking eye drops preserved with benzalkonium chloride show an adverse effect on the precorneal tear film, which can be measured by checking the break-up-time (BUT). To decide, whether this adverse effect is caused more by the beta-blocking drug or the preservative, we tested the influence of timolol eye drops without preservative in single dose units Timosine) on the BUT in a prospective, open study. These eyedrops caused no significant shortening of the BUT in persons, which where untreated before. Patients using preserved beta-blocking eye drops and having irritations of their eyes showed significant prolongation of the BUT after changing the therapy to Timosine. Preservative-free beta-blocking eye drops are a real improvement in the therapy of glaucoma patients with irritated eyes.

Glaucoma↗
PubMed1991

Central cholinergic functioning and aging.

Normal aging in experimental animals and humans has been demonstrated to affect various aspects of central cholinergic functions. Although deficits at the levels of the number of cholinergic neurons, the acetylcholine synthesis, and the number of muscarinic cholinergic receptors are probably less relevant, deficits at the levels of acetylcholine release, muscarinic cholinergic receptor plasticity, as well as muscarinic cholinergic receptor function are fairly pronounced and seem to justify the assumption that the functioning of the central cholinergic system is impaired by aging. However, whether these cholinergic deficits of normal aging are the sole neurochemical basis to explain age-associated memory impairment or whether other transmitter systems also play a role is still a matter of controversy.

Aging↗
PubMed1990

Lithium but not cholinergic ligands influence guanylate cyclase activity in intact human lymphocytes.

The presence of guanylate cyclase in intact circulating human lymphocytes and the sensitivity of this enzyme to stimulation by sodium nitroprusside could be confirmed. However, in contrast to other observations all attempts failed to stimulate the enzyme by cholinergic agonists, despite the use of M1 as well as M2 selective agonists. These findings do not support the assumption that cholinergic recognition sites on human lymphocytes described by many groups are part of a functioning muscarinic transducing mechanism. While several other neuroreceptor agonists were also unable to affect lymphocyte guanylate cyclase activity, lithium was found to potently inhibit the stimulation of guanylate cyclase by sodium nitroprusside at an intracellular concentration close to the therapeutic plasma levels. It is suggested that the effects of lithium on guanylate cyclase activity in human lymphocytes could be related to a possible mechanism of action of lithium in affective disorders.

Adult↗
PubMed1990

[Plate osteosynthesis of the femur in patients with multiple and mono-trauma].

In multiple trauma patients successful treatment of femur shaft fractures depends more on timing of osteosynthesis than on choosing a specific type of fracture stabilization. Because of theoretical and practical reasons early osteosynthesis within 24 to 48 hours seems to be advantageous. In our experience it led to a significant decrease in complications. However, concomitant thorax trauma mandates special consideration. The two fatalities in our study belonged to this subgroup. With adequate indication for therapeutic intervention, correct operative technique and consideration of the patient's general status good results can be expected with every type of fracture treatment available (external fixation, plate fixation, intramedullary nailing).

Adult↗
PubMed1990

[Use of UV radiation for the disinfection of water. V. Microbiological studies of the behavior of bacterial cells from the logarithmic and from the stationary phase in cold and warm drinking water].

The u.v.-susceptibility of E. cloacae, E. coli and E. faecium was tested with a flow-through u.v. light treatment apparatus. Drinking water of three ranges of temperature (ca. 13 degrees C, ca. 33 degrees C, and ca. 48 degrees C) was used. The u.v.-susceptibility was tested with bacteria harvested in the exponential phase of growth as well as with bacteria harvested in the stationary phase. In all ranges of temperature and both phases of growth reductions of at least 99.9999% of E. cloacae and E. coli were obtained by a dosage of less than or equal to 25 mWs/cm2. For E. faecium harvested in the exponential phase of growth this could be confirmed in cold water of 13 degrees C, while in warm water of 48 degrees C a dosage of ca. 47 mWs/cm2 for a reduction of 99.9999% was necessary. To kill E. faecium-cells, which were harvested in the stationary phase, dosage between 39 and 45 mWs/cm2 were necessary in water of the three ranges of temperature.

Bacteria↗
PubMed1990

[Hypothermia and polytrauma. A case report (28 degrees C)].

In a 29-year-old polytraumatised motorbike driver, massive blood transfusion led to a decrease of the body temperature to 28.1 degrees C rectal on the second day after admission. We could rewarm the patient using only a Clinitron bed, although he had persisting blood loss due to an intravasal coagulopathy. This method has proven to be noninvasive, effective and without any side effects.

Adult↗
PubMed1990

Endoscopic therapy and early elective operation as a therapeutic regimen in ulcer bleeding.

In a prospective protocol we treated 63 consecutive patients admitted to our surgical department with bleeding gastroduodenal ulcers between January 1986 and December 1987. The therapeutic regimen included emergency endoscopy in all cases. Active Forrest Ia or II hemorrhage was treated endoscopically with submucosal injection. Endoscopic control of hemorrhage was achieved in all but one case. Low-risk ulcers, e.g. Forrest II without visible vessel and III or ulcers caused by antirheumatic drug medication were treated definitively by therapeutic endoscopy (31 patients). Ulcers with high risk of rebleeding even after endoscopic therapy underwent additional early elective operation. Thirty patients were treated surgically by this means. Two patients required emergency operation because of failure to control the bleeding (Ia and second rebleeding) endoscopically. The overall mortality of the surgically treated patients was 6% (2/32). The mortality of the therapeutic endoscopy was 0%. Thus, the mortality of the overall group was 3%. The major advantages of this concept were: low mortality rates, elimination of rebleeding in the follow-up period, optimal conditions for the surgical therapy resulting in low death-rates and a reduced need for transfusions.

Adult↗
PubMed1989

N-formyl-methionyl-leucyl-phenylalanine induced accumulation of inositol phosphates indicates the presence of oligopeptide chemoattractant receptors on circulating human lymphocytes.

Using [3H]-inositol-labeled human lymphocytes, formation of inositolphosphates was found as a specific response to the chemotactic formylpeptide, N-formyl-methionyl-leucyl-phenylalanine (fMLP), in a fashion similar to the effects of fMLP in human granulocytes. Inositol phosphate formation could be significantly augmented by lithium ions. The results suggest that fMLP-mediated hydrolysis of phosphoinositides is involved in its chemotactic effects on human lymphocytes.

Adult↗
PubMed1989

Twice-daily sucralfate dosing to heal acute duodenal ulcer. Multicenter Study Group.

Twice-daily dosing with sucralfate was evaluated by two multicenter trials, trial 1 (eight weeks) and trial 2 (four weeks). Both trials demonstrated significantly better ulcer healing at study completion for the 2-g twice daily (B.I.D.) regimen compared with placebo. Both trials were double-blind, randomized, and placebo-controlled, with parallel groups. Patients received two doses daily consisting of sucralfate 2 g B.I.D., placebo/sucralfate 2 g at bedtime (H.S.), or placebo/placebo. Ulcer healing was assessed by scheduled endoscopy and symptom assessment. Healing was defined as complete absence of erosion or ulceration. Trial 1 evaluations were conducted at four and eight weeks, trial 2 evaluations at two and four weeks. Interim examinations were performed at investigator discretion. Treatment groups were comparable with regard to number of patients, age, sex, smoking status, ulcer size, and presence/absence of baseline symptoms. Sucralfate 2 g B.I.D. was significantly better than H.S. or placebo dosing at the completion of each trial. H.S. dosing was better than placebo only at the four-week analysis of trial 1. At Week 4 of trial 1, 14 of 54 patients (26 percent) were healed with the B.I.D. sucralfate regimen, whereas at Week 8, 41 of 54 (76 percent) were healed (p less than 0.001). For the placebo/sucralfate H.S. group, 17 of 57 patients (30 percent) were healed at Week 4 (p less than 0.05), and 32 of 56 patients (57 percent) were healed at Week 8. For the placebo group, six of 52 (12 percent) and 20 of 51 patients (39 percent) were healed at Weeks 4 and 8, respectively. In trial 2, the B.I.D. group had a 21 percent healing rate at Week 2 (13 of 61 patients) and 62 percent were healed at Week 4 (38 of 61 patients; p less than 0.05). The H.S. group had an 8 percent healing rate (five of 66 patients) at Week 2 and 50 percent (33 of 66 patients) at Week 4. For the placebo group, 10 of 62 patients (16 percent) and 26 of 62 patients (42 percent) were healed at Weeks 2 and 4, respectively. Trial 1 demonstrated significant symptom improvement for active treatment groups at both four and eight weeks, whereas no differences were found in trial 2. Sucralfate 2 g B.I.D. was found to be safe and effective for the treatment of acute duodenal ulcer.

Acute Disease↗