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Biomedical subjects

A Frick

Publications and source records attributed to A Frick.

At least 19 recordsLinked to original sources
PubMed2006

[Re-intervention after carpal tunnel release].

In the last eight years we performed 63 re-interventions because of recurrent carpal tunnel syndromes. Intact parts of the retinaculum were the reason for persistent symptoms in 38 patients. 21 patients suffered from scar tethering, two patients from circumferential fibrosis of the nerve. In one patient a ganglion and in another patient a direct injury to the median nerve was detected. In 21 patients short incisions were performed in the primary procedures. Since the introduction of endoscopic carpal tunnel release, an open decompression via a short incision is recommended as an alternative. Since then we encounter an increase of necessary operative revisions after short incisions. Optical tools may increase the survey especially in short incisions. In extended teno-synovialitis of the flexor tendons, a longer incision over the wrist enables adequate conditions for a safe teno-synovialectomy. The length of the incision has to be chosen according to the pathologic-anatomic situation, the disposable equipment and the experience of the surgeon.

Adult↗
PubMed2004

Plasma amisulpride levels in schizophrenia or schizoaffective disorder.

The atypical antipsychotic drug amisulpride is a benzamide with specific antagonistic properties, which target dopamine D(2) and D(3) receptors, preferentially in the limbic system. Amisulpride is readily absorbed from the gastrointestinal tract, distributed to all body systems with little binding to plasma proteins. Elimination occurs mainly through the kidneys as unchanged drug. In contrast, hepatic metabolism is of minor significance and primarily yields two inactive metabolites. Very little is known about the plasma concentrations of amisulpride in patients at varying oral doses or about clinically relevant interactions with co-medication. The aim of the present investigation was to elucidate the factors, which affect amisulpride levels in schizophrenic patients. The plasma amisulpride levels of 85 patients with schizophrenia or schizoaffective disorder (mean age: 34.0+/-11.4 years; 40 women, 45 men) were assessed by high-performance liquid chromatography (HPLC) with fluorometric detection. The average daily dose of amisulpride was 772.3 mg (S.D. 346.7 mg) and the mean amisulpride plasma concentration was 424.4 ng/ml (S.D. 292.8 ng/ml). The interindividual variance of the amisulpride plasma concentration was high; furthermore, the plasma concentration increased linearly with the daily oral dose (r=0.50, p<0.001). Age and gender showed a significant effect on the dose-corrected amisulpride plasma concentrations-older patients and women had higher dose-corrected amisulpride plasma concentrations than younger patients and men. However, cigarette consumption had no effect on the amisulpride plasma concentrations. Regarding co-medication with lithium and/or clozapine, significantly higher amisulpride plasma concentrations were found as compared to monotherapy, whereas other co-medications such as benzodiazepines and various conventional antipsychotics had no effect on the amisulpride plasma concentrations. The results, the possible pathomechanisms and the clinical relevance are discussed. The findings need to be confirmed in larger patient samples and with a wider range of co-medications.

Adolescent↗
PubMed2004

Dependency of the metabolic effect of sc-injected human regular insulin on intra-abdominal fat in patients with type 2 diabetes.

Ten patients with type 2 diabetes were enrolled in an isoglycemic glucose clamp study to determine the impact of intra-abdominal fat, subcutaneous abdominal fat and total abdominal fat on the metabolic effect of a single bolus (0.2 IU/kg) of sc-injected human regular insulin. The maximum metabolic effect associated highly and negatively with intra-abdominal fat (r = - 0.72, p < 0.02) and with the homeostasis model assessment insulin resistance score (HOMA, r = - 0.71, p < 0.03). Likewise, the total metabolic effect of sc-injected insulin correlated strongly and negatively with intra-abdominal fat (r = - 0.77, p < 0.01), HOMA (r = - 0.74, p < 0.02) and HbA (1c) (r = - 0.70, p < 0.03). Stepwise multiple regression analyses showed that the highest metabolic effect was only significantly predicted by intra-abdominal fat, indicating a high negative correlation with the maximum effect (beta = - 0.72) whereas time to maximum metabolic effect showed a strong (beta = 0.72) and positive correlation with HOMA. In combination with the HOMA, it is intra-abdominal fat, and not subcutaneous abdominal fat, which explains 50 - 75 % of the variability of the effect of sc human regular insulin in patients with type 2 diabetes.

Abdomen↗
PubMed2004

Olanzapine plasma concentration, average daily dose, and interaction with co-medication in schizophrenic patients.

BACKGROUND: Olanzapine, a thienobenzodiazepine, is one of the relatively new atypical antipsychotic drugs. The lowest threshold of effective olanzapine plasma levels in inpatient treatment is assumed to be 9 ng/ml. Very little is known about the plasma concentration in patients at various oral doses of olanzapine or about the clinically relevant interactions with co-medications. METHODS: In 71 schizophrenic patients (age 32.6 +/- 12.1, range 18-63 years; 31 women, 40 men), plasma olanzapine levels were assessed in 377 tests by high-performance liquid chromatography (HPLC) with electrochemical detection. Fifty-six of these plasma levels were assessed while patients were receiving olanzapine as monotherapy; otherwise, the plasma levels were assessed with the patients receiving various co-medications. RESULTS: The mean daily oral dose of olanzapine was 17.5 mg (SD = 7.0, range 5-40 mg), and the mean olanzapine plasma concentration was 54.2 ng/ml (SD 37.8 ng/ml, range 1.2-208 ng/ml). The plasma concentration of olanzapine increased linearly with the daily oral dose (r = 0.64, p < 0.001). A multiple variance analysis considering age and sex as covariables showed a significant difference in the dose-corrected plasma levels of olanzapine among 40 smokers and 31 non-smokers; age and sex did not affect the dose-corrected plasma levels. However, women received a significantly lower daily dose of olanzapine under routine clinical study conditions. No differences could be detected among the dose-corrected plasma concentration of those patients who were taken off olanzapine because they did not respond (n = 14) or because of side effects (n = 5) and those who were discharged while still on olanzapine. Under the co-medication with fluvoxamine, significantly higher dose-corrected olanzapine plasma concentrations were found than with olanzapine monotherapy, whereas significantly lower dose-corrected olanzapine plasma concentrations were detected under lithium and trimipramine co-medication. Under co-medication with amitriptyline, benperidol, carbamazepine, flupentixol, and lorazepam, the dose-corrected olanzapine plasma concentrations were no different than the plasma levels under olanzapine monotherapy. CONCLUSIONS: The relevance of therapeutic drug monitoring is emphasized with respect to the data presented and to the literature. Future studies should examine, in particular, the effects of a wider range of co-medications in a larger patient sample.

Adolescent↗
PubMed2003

Endoscopic-assisted microsurgery: microsurgery in the new millennium? A comparative experimental study.

Endoscopes are already present in almost all plastic surgery departments. The operating microscope is currently an essential piece of equipment for performing microsurgical anastomoses; however, microsurgery could be conducted using other equipment, including the endoscope. By performing 60 vessel and nerve repairs in rats under the operating microscope and the same number using the endoscope as a visual aid, we investigated the technical and clinical differences between the two instruments. We recorded significantly shorter operative, vascular preparation and anastomotic times in the endoscopically assisted group. Based on the data collected during this study, we conclude that microsurgery is possible with the aid of an endoscope. Using the endoscope may make prolonged microvascular procedures shorter and less physically demanding and may increase the comfort level of both the surgeon and the assistant.

Anastomosis, Surgical↗
PubMed2003

Omeprazole reduces clozapine plasma concentrations. A case report.

A number of interactions of the atypical antipsychotic clozapine with other drugs are well known, some of which can be attributed in part to the pharmacokinetic interactions associated with cytochrome P450 enzymes during drug metabolism. Clozapine is mainly metabolized by the cytochrome P450 isoenzyme 1A2. The proton pump inhibitor omeprazole can induce CYP1A2. We report on two patients with schizoaffective disorder who received omeprazole in addition to clozapine because of gastrointestinal complaints. Before the co-medication with omeprazole was started, the patients had been receiving clozapine for 78 and 41 days and for 40 and 8 days at a stable daily dose of 325 mg (patients 1 and 2, respectively). The co-medication with omeprazole was associated with a reduction in the plasma levels of clozapine of 41.9 % and 44.7 %, respectively, in these patients. The decrease in the plasma concentrations of clozapine in the presence of omeprazole might be due to the induction of the cytochrome P450 isoenzyme CYP1A2. If patients are receiving omeprazole as co-medication, close monitoring of plasma clozapine levels is recommended. If clozapine levels drop, the drug should be adjusted accordingly. If necessary, an alternative to omeprazole should be chosen.

Adult↗
PubMed2003

[The microsurgical lymph vessel transplantation].

Using advanced microsurgical techniques, single lymph vessels can be safely anastomosed and segments of lymphatics can bridge localized lymphatic blockades which are mostly due to lymphadenectomies. Lymphatic grafts are harvested from the patient's thigh with a length up to about 30 cm. In the case of an axillary blockade they are anastomosed with ascending lymph vessels at the upper arm and lymph vessels at the supraclavicular region. Unilateral oedemas of lower extremities are treated by transferring the grafts via the symphysis and anastomosing them with ascending lymphatics at the affected side. Lymphoedemas of the penis and the scrotum as well as lymphoedemas due to a localized peripheral lymphatic blockade can be treated by lymphatic grafts. In 127 arm oedemas the original difference in volume between the affected and the healthy arm was reduced at two third from 3368 cm (3) to 2567 cm(3) (p < 0.001). After a follow-up period of 2.6 years the volume was reduced to 2625 cm(3) (p < 0.001). The group of patients with a follow-up of at least ten years showed a volume of 2273 cm(3) (p < 0.001). The volume of unilateral lower extremity-lymphoedemas was reduced from 13 098 cm(3) to 10 578 cm(3) (p < 0.001) and showed a volume of 11 074 cm(3) after 1.7 years (p < 0.001) and 10 692 cm(3) after four years (p < 0.001). The original mean volume of the healthy contralateral leg was 9371 cm(3). Bridging localized gaps in the lymphatic system by autologous lymphatic grafts showed long lasting stable results. Starting the treatment of lymphoedemas by conservative procedures, one should not wait too long to ascertain the possibility of a microsurgical reconstruction in order to avoid increasing secondary tissue changes.

Adult↗
PubMed2002

[Vascularisation of a free jejunal graft at the neck in an insufficient vascular situation].

Free jejunal grafts are the method of choice for one-stage reconstruction of the hypopharynx and the upper esophagus. Prerequisites for a successful free transplantation are a sufficient arterial vascularisation and a corresponding venous drainage. In a 59-year old patient, an esophagectomy was performed because of a proximal esophageal cancer. The passage was primarily reconstructed by a pedicled colon interposition. Necrosis of the cranial graft occurred. After resection of the necrotic bowel, a free jejunal graft was introduced thoraco-cervically. The nutrient vessels of the graft were anastomosed to the upper thyroid artery and the vena thyroid ima. In an operative revision one day postoperatively due to lacking re-capillarisation, the arterial inflow stopped. The superior thyroid artery was cut at its cranial origin at the external carotid artery and microsurgically implanted into the common carotid artery. Hereafter, a venous outflow was re-established. But the critical time of ischaemia was exceeded. In another operative revision, the cephalic vein was exposed at the cranial upper arm, distally cut and anastomosed to the re-implanted superior thyroid artery. After the harvest of a second autogenous jejunal graft, the arterio-venous shunt was cut and the segments were anastomosed to the mesenterial artery and vein. Transpositions of arteries and veins with temporary formation of an arterio-venous shunt may be prerequisites for a sufficient vascularisation and can enable a successful free microsurgical transplantation even in critical vascular situations.

Anastomosis, Surgical↗
PubMed2001

Microembolic signal counts increase during hyperbaric exposure in patients with prosthetic heart valves.

BACKGROUND: Patients with prosthetic heart valves have an increased risk of thromboembolic events, and transcranial Doppler sonography reveals microembolic signals. Whereas microembolic signals were initially assumed to be of particulate matter, recent studies suggest that they are partially gaseous in origin. If this is true, alteration of environmental pressure should change microembolic signal counts. We undertook this study to evaluate the influence of hyperbaric exposure on microembolic signal counts in persons with prosthetic heart valves. METHODS AND RESULTS: Microembolic signal counts were monitored by transcranial Doppler sonography of both middle cerebral arteries under normobaria (normobaria 1), 2 subsequent periods of hyperbaria (2.5 and 1.75 bar), and a second period of normobaria (normobaria 2) in 15 patients with prosthetic heart valves. Each monitoring period lasted 30 minutes. Compression and decompression rates were 0.1 bar/min. Microembolic signal counts increased from 20 (12-78) at normobaria 1 to 79 (30-165) at 2.5 bar (P <.01 vs normobaria 1 and 2), decreased to 44 (18-128) at 1.75 bar (P <.01 vs normobaria 1 and 2.5 bar; P <.001 vs normobaria 2), and returned to 20 (8-96) at normobaria 2 (values are medians and 95% confidence intervals). CONCLUSIONS: Our results strongly suggest that gaseous bubbles are underlying material for part of the microembolic signals detected in patients with prosthetic heart valves.

Aortic Valve↗
PubMed2001

Glutamate receptors form hot spots on apical dendrites of neocortical pyramidal neurons.

Apical dendrites of layer V cortical pyramidal neurons are a major target for glutamatergic synaptic inputs from cortical and subcortical brain regions. Because innervation from these regions is somewhat laminar along the dendrites, knowing the distribution of glutamate receptors on the apical dendrites is of prime importance for understanding the function of neural circuits in the neocortex. To examine this issue, we used infrared-guided laser stimulation combined with whole cell recordings to quantify the spatial distribution of glutamate receptors along the apical dendrites of layer V pyramidal neurons. Focally applied (<10 microm) flash photolysis of caged glutamate on the soma and along the apical dendrite revealed a highly nonuniform distribution of glutamate responsivity. Up to four membrane areas (extent 22 microm) of enhanced glutamate responsivity (hot spots) were detected on the dendrites with the amplitude and integral of glutamate-evoked responses at hot spots being three times larger than responses evoked at neighboring sites. We found no association of these physiological hot spots with dendritic branch points. It appeared that the larger responses evoked at hot spots resulted from an increase in activation of both alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptors and not a recruitment of voltage-activated sodium or calcium conductances. Stimulation of hot spots did, however, facilitate the triggering of both Na+ spikes and Ca(2+) spikes, suggesting that hot spots may serve as dendritic initiation zones for regenerative spikes.

Action Potentials↗
PubMed2000

[Possible variations of free autogenous jejunum transplantation for differential reconstruction of the oropharynx].

INTRODUCTION: Resections of extensive tumours, recurrences and radiodermatitides at the neck cause complex defects. Free bowel transplantation enables one-stage reconstruction. PATIENTS AND METHODS: In 35 out of 57 interdisciplinarily treated patients, small-bowel transplantation was performed for reconstruction. Thirty patients received cylinder grafts, five jejunal patch plastics. In four patients neoglottis formations according to Ehrenberger were performed. To cover soft tissue defects, two patients received scapular free flaps, eight patients a jejunal segment, incised at the anti-mesenteric side, the mucosa stripped and covered by a split skin graft. RESULTS AND CONCLUSIONS: Thirty-four grafts were viable. One patient received a successful re-transplantation. One postoperative fistula at the hypo-pharyngojejunostomy was closed by a separated jejunal segment which was primarily used as monitor, two others by pectoral flaps. Separation of a jejunal graft into two or three segments enables restoration of swallowing, voice and covering soft tissue in a one-stage procedure. The whole reconstruction necessitates only one arterial and one venous microanastomosis at the neck.

Adult↗
PubMed2000

Effects of lamotrigine on field potentials and long-term potentiation in guinea pig hippocampal slices.

PURPOSE: To investigate the effects of lamotrigine (LTG), a new anticonvulsant, on neuronal excitability, synaptic transmission, and long-term potentiation (LTP) in guinea pig hippocampal slices. METHODS: Electrically evoked field excitatory postsynaptic potentials (fEPSPs) and population spikes (PSs) were investigated in the CA1 region of the hippocampus. RESULTS: The concentration-response curves showed different actions of LTG in concentrations near therapeutic plasma levels (10 microM) on fEPSPs and PSs. The initial slopes of fEPSPs were not affected, whereas the amplitudes of PSs were significantly decreased. Higher concentrations of LTG decreased both fEPSP slopes and PS amplitudes; however, the effects on PSs were much stronger. Also, there were no differences in fEPSP slopes or PS amplitudes compared with controls when LTP was induced in the presence of LTG (10 microM). CONCLUSIONS: Our data are in contrast to previous findings that suggest LTG acts primarily on presynaptic sites by blocking the release of excitatory amino acids. Further, LTP was not affected by LTG.

Animals↗
PubMed1999

Precisely localized LTD in the neocortex revealed by infrared-guided laser stimulation.

In a direct approach to elucidate the origin of long-term depression (LTD), glutamate was applied onto dendrites of neurons in rat neocortical slices. An infrared-guided laser stimulation was used to release glutamate from caged glutamate in the focal spot of an ultraviolet laser. A burst of light flashes caused an LTD-like depression of glutamate receptor responses, which was highly confined to the region of "tetanic" stimulation (<10 micrometers). A similar depression of glutamate receptor responses was observed during LTD of synaptic transmission. A spatially highly specific postsynaptic mechanism can account for the LTD induced by glutamate release.

Animals↗
PubMed1999

Pentachlorophenol exposure in women with gynecological and endocrine dysfunction.

Exposure to wood preservatives containing pentachlorophenol (PCP) was detected in 65 women who consulted the Endocrinological Department of the University Hospital of Obstetrics and Gynecology, Heidelberg, Germany, because of gynecological problems. Blood PCP levels ranged from 20.7 to 133 microg per liter of serum. One hundred and six women with similar clinical conditions, corresponding age and body weight, no PCP exposure in history, and PCP levels below 20 microg per liter of serum served as control group. Significant associations were found between serum PCP concentrations, age, and different parameters of the endocrine system. PCP may act centrally on a hypothalamic or suprahypothalamic level which may result in mild ovarian and adrenal insufficiency. PCP may, therefore, play a role in the increasing infertility problem.

Adrenal Cortex Hormones↗
PubMed1999

Secondary ischaemia in experimental free flaps--treatment by long acting prostacyclin analogues.

Secondary postoperative ischaemia due to venous occlusion is the most detrimental insult to free microvascular flaps. In an experimental rat free flap model the efficacy of long acting prostacyclin analogues iloprost (Ilomedin) and cicaprost in venous occlusion induced postoperative ischaemia was studied. Free, microvascular groin flaps were transplanted to the neck and the draining veins were temporarily occluded on the first postoperative day for a total of 20 min. In the untreated control group, haemorrhagic flap necrosis occurred. Intravital microscopy after secondary ischaemia revealed flap areas without reperfusion. The functional vessel density was significantly reduced. Reperfused capillaries were tortuous and significantly dilated. After reperfusion the interstitial leakage of macromolecular dextran increased, indicating loss of microvascular endothelial integrity. Intraarterial and intravenous applications of iloprost were able to diminish the ischaemic effects, giving a flap survival rate of 83%. Similar results were obtained by intravenous and enteral administration of cicaprost. Transcutaneous oxygen partial pressure measurements confirmed the viability of the surviving flaps. We conclude that both iloprost and cicaprost are effective in preventing venous occlusion induced failure of free microvascular groin flaps.

Animals↗
PubMed1999

Efficacy of silver-coating central venous catheters in reducing bacterial colonization.

OBJECTIVE: To compare silver-coated and uncoated central venous catheters regarding bacterial colonization. To assess the relative contribution of catheter hub and skin colonization to catheter tip colonization. DESIGN: Prospective, randomized clinical trial. SETTING: Intensive care unit in a university hospital. PATIENTS: Patients after cardiac surgery who required a central venous double-lumen catheter (DLC). INTERVENTIONS: Sixty-seven adult patients were prospectively randomized to receive either a silver-coated (S group, n = 34) or an uncoated control (C group, n = 33) DLC. Blood cultures were drawn at catheter removal, and removed catheters were analyzed with quantitative cultures. Typing of microorganisms included DNA fingerprinting. MEASUREMENTS AND MAIN RESULTS: Catheters were removed if no longer necessary and aseptically divided into three segments: segment A, the catheter tip; segment B, an intermediate section; and segment C, the subcutaneous portion. Bacterial catheter colonization was quantitatively measured using sonication to detach adherent bacteria from the catheter segments in the broth and subsequent culture of an aliquot. Selected isolates of coagulase-negative staphylococci and other bacteria from catheter segments were examined by means of pulsed-field gel electrophoresis (PFGE) after macrorestriction digestion of bacterial DNA to study colonization pathogenesis. Quantitatively lower bacterial colonization could be demonstrated on the silver-coated catheters (200 +/- 550 colony forming units [CFUs]/cm catheter segment; mean +/- SD). The difference in the control catheters (1120 +/- 5350 CFUs/cm catheter segment; mean +/- SD) was not, however, significant (p = .25). The frequency of colonization of at least one catheter segment was 52.9% for the silver-coated catheters and 57.6% for the control catheters (p= .44), without any significant differences in the colonization of corresponding catheter segments. The rate of significant catheter colonization (i.e., > or = 10(3) CFUs/cm catheter by quantitative catheter culture or > or = 10(3) CFUs/mL by luminal flush) was nine in the silver group and seven in the control group, a difference that failed to reach significance (p = .41). Two patients in both groups developed catheter-related bacteremia. Pattern analysis after PFGE demonstrated that about 70% of the isolates found on the catheter tip were identical with those on the skin at the insertion site, whereas about 75% were identical with those recovered from the hub. In 29% of colonized catheters, identical bacteria were found on the hub and the skin at the insertion site. CONCLUSIONS: Silver-coating of DLCs did not significantly reduce bacterial catheter colonization compared with the control catheters. PFGE analysis of coagulase-negative staphylococci and other bacteria demonstrated various pathogenic routes of catheter-related colonization, whereby the microorganisms of the skin flora around the insertion site must be regarded as the main source of catheter-related infections.

Adult↗
PubMed1999

Liposuction technique and lymphatic lesions in lower legs: anatomic study to reduce risks.

Liposuction is a standard procedure in plastic surgery. Especially, lipectomy with suction of the lower extremities has been of greater interest in recent years. Until now, however, there was no definite information about the integrity of epifascial lymph collectors during this procedure. To study the effect of liposuction devices on lymph vessel injury, postmortem lymphatic preparations were done in five human cadavers (10 lower extremities). Conventional liposuction with a blunt 4-mm cannula and a dry technique was used. Adiposuction was performed either in parallel to the extremity axis and, therefore, in parallel to the superfascial lymph vessels or transversally in an 80- to 90-degree angle to the extremity. Careful surgical preparation of the regions followed. A specific macroscopic lymph vessel injury score was applied to differentiate 3 degrees of lymph vessel lesions according to the extravasation of patent blue. In all lower extremities, postmortem lymph flow occurred as indicated by patent blue staining of the lymph vessels. Lymph vessel injury was more severe in areas where liposuction was performed transversally, vertical to the extremity's axis, than in those after a longitudinal procedure. The difference was statistically significant (p < 0.01). The volumes of adipoaspirate and of the compared regions were comparable between both groups, verified by circumference measurements. Longitudinal liposuction of the lower extremities is unlikely to cause major lesions of epifascial lymph vessels and, therefore, should be preferred in comparison to liposuction vertical to the extremity.

Aged↗