PubMed Health⌕ Search

Biomedical subjects

M Specht

Publications and source records attributed to M Specht.

At least 19 recordsLinked to original sources
PubMed2002

Hand-assisted laparoscopic autoaugmentation gastrocystoplasty.

BACKGROUND: Autoaugmentation gastrocystoplasty has been previously performed successfully. This set of experiments was conducted to determine the feasibility of performing autoaugmentation gastrocystoplasty laparoscopically. METHODS: Hand-assisted laparoscopic autoaugmentation gastrocystoplasty was performed on 15 mongrel dogs. The surgery was carried out with two 10-mm trocars and a 6-cm Pfannenstiel incision. The gastric wedge, supplied by the right gastroepiploic artery, was resected with two applications of an endoscopic gastrointestinal anastomosis (GIA) stapler. The pedicle was demucosalized, and the anastomosis to the bladder was completed through the Pfannenstiel incision. RESULTS: All of the dogs were successfully treated laparoscopically and were eating at 48 h. There was no evidence of anastomotic leak dehiscence at the gastric resection staple line. CONCLUSION: Hand-assisted laparoscopic autoaugmentation gastrocystoplasty can be performed successfully in dogs. This operation may offer a superior alternative to standard bladder autoaugmentation procedures in children suffering from congenital bladder disorders.

Animals↗
PubMed2001

Hand-assisted demucosalized gastrocystoplasty comparing different tissue closure methods.

OBJECTIVES: To perform experiments to determine whether a new tissue sealant (SynthaSeal) could be an alternative for suture closure in minimally invasive bladder autoaugmentation gastrocystoplasty using demucosalized stomach. Alternative methods to suture closure for tissue approximation such as laser tissue welding and fibrin glue have been reported. METHODS: Minimally invasive autoaugmentation gastrocystoplasty with demucosalized stomach was performed on 14 female mongrel dogs. Two dogs were used to refine the technique. The remaining dogs were assigned to a suture group (n = 6) or a SynthaSeal group (n = 6). Anastomoses were performed using either SynthaSeal or suture. The in vivo bladder volumes and pressures of the groups were measured before and after gastrocystoplasty. The animals were studied on day 14. Samples of the anastomotic area were taken to measure the tensile strength and stress. Histologic analysis was conducted to assess tissue healing. The anastomotic time was recorded for each group. RESULTS: The tensile strength of the anastomoses in the SynthaSeal group was significantly increased (9.99 +/- 1.14 Newtons) compared with the suture group (5.66 +/- 0.97 Newtons) (P <0.05). The breaking stress comparisons and anastomosis times were equivalent between the two groups. The histologic evaluation revealed minor tissue devitalization and a normal inflammatory response in both groups. CONCLUSIONS: Minimally invasive gastrocystoplasty using demucosalized stomach can be successfully performed with SynthaSeal tissue sealant. This may provide a reliable alternative to suture closure.

Anastomosis, Surgical↗
PubMed2001

Time-variant non-linear phase-coupling analysis of EEG burst patterns in sedated patients during electroencephalic burst suppression period.

OBJECTIVES: The quadratic phase-coupling (QPC) within burst patterns during electroencephalic burst suppression has been quantified. METHODS: It can be shown that a QPC exists between the frequency ranges 0-2.5 and 3-7.5 Hz and between the frequency ranges 0-2.5 and 8-12 Hz. By means of time-variant bicoherence analysis, a strong phase-locking between the modulating and the modulated component can be identified. The phase-locking is demonstrable within the first 250 ms after the burst onset and comes up to the maximum between 750 and 1250 ms. RESULTS: The effect is maintained over the whole first part of the burst (2 s) with a decreasing tendency after 1250 ms. All these effects cannot be found in the EEG before entering the burst suppression period (BSP). The transient coupling phenomena in the EEG bursts during BSP can be regarded as indicators for short-term interrelations between the underlying electrophysiologic processes. CONCLUSIONS: It can be suggested that the method introduced for the quantification of the sedation depth should be used.

Cerebrospinal Fluid Pressure↗
PubMed2001

Biotransformation of biphenyl by Paecilomyces lilacinus and characterization of ring cleavage products.

We examined the pathway by which the fungicide biphenyl is metabolized in the imperfect fungus Paecilomyces lilacinus. The initial oxidation yielded the three monohydroxylated biphenyls. Further hydroxylation occurred on the first and the second aromatic ring systems, resulting in the formation of five di- and trihydroxylated metabolites. The fungus could cleave the aromatic structures, resulting in the transformation of biphenyl via ortho-substituted dihydroxybiphenyl to six-ring fission products. All compounds were characterized by gas chromatography-mass spectroscopy and proton nuclear magnetic resonance spectroscopy. These compounds include 2-hydroxy-4-phenylmuconic acid and 2-hydroxy-4-(4'-hydroxyphenyl)-muconic acid, which were produced from 3,4-dihydroxybiphenyl and further transformed to the corresponding lactones 4-phenyl-2-pyrone-6-carboxylic acid and 4-(4'-hydroxyphenyl)-2-pyrone-6-carboxylic acid, which accumulated in large amounts. Two additional ring cleavage products were identified as (5-oxo-3-phenyl-2,5-dihydrofuran-2-yl)-acetic acid and [5-oxo-3-(4'-hydroxyphenyl)-2,5-dihydrofuran-2-yl]-acetic acid. We found that P. lilacinus has a high transformation capacity for biphenyl, which could explain this organism's tolerance to this fungicide.

Biotransformation↗
PubMed2001

Novel ring cleavage products in the biotransformation of biphenyl by the yeast Trichosporon mucoides.

The yeast Trichosporon mucoides, grown on either glucose or phenol, was able to transform biphenyl into a variety of mono-, di-, and trihydroxylated derivatives hydroxylated on one or both aromatic rings. While some of these products accumulated in the supernatant as dead end products, the ortho-substituted dihydroxylated biphenyls were substrates for further oxidation and ring fission. These ring fission products were identified by high-performance liquid chromatography, gas chromatography-mass spectrometry, and nuclear magnetic resonance analyses as phenyl derivatives of hydroxymuconic acids and the corresponding pyrones. Seven novel products out of eight resulted from the oxidation and ring fission of 3,4-dihydroxybiphenyl. Using this compound as a substrate, 2-hydroxy-4-phenylmuconic acid, (5-oxo-3-phenyl-2,5-dihydrofuran-2-yl)acetic acid, and 3-phenyl-2-pyrone-6-carboxylic acid were identified. Ring cleavage of 3,4,4'-trihydroxybiphenyl resulted in the formation of [5-oxo-3-(4'-hydroxyphenyl)-2,5-dihydrofuran-2-yl]acetic acid, 4-(4'-hydroxyphenyl)-2-pyrone-6-carboxylic acid, and 3-(4'-hydroxyphenyl)-2-pyrone-6-carboxylic acid. 2,3,4-trihydroxybiphenyl was oxidized to 2-hydroxy-5-phenylmuconic acid, and 4-phenyl-2-pyrone-6-carboxylic acid was the transformation product of 3,4,5-trihydroxybiphenyl. All these ring fission products were considerably less toxic than the hydroxylated derivatives.

Biodegradation, Environmental↗
PubMed2000

Cometabolic degradation of dibenzofuran by biphenyl-cultivated Ralstonia sp. strain SBUG 290.

Cells of the gram-negative bacterium Ralstonia sp. strain SBUG 290 grown in the presence of biphenyl are able to cooxidize dibenzofuran which has been 1,2-hydroxylated. Meta cleavage of the 1, 2-dihydroxydibenzofuran between carbon atoms 1 and 9b produced 2-hydroxy-4-(3'-oxo-3'H-benzofuran-2'-yliden)but-2-enoic acid, which was degraded completely via salicylic acid. The presence of these intermediates indicates a degradation mechanism for dibenzofuran via lateral dioxygenation by Ralstonia sp. strain SBUG 290.

Benzofurans↗
PubMed1999

Interrelations between EEG frequency components in sedated intensive care patients during burst-suppression period.

The EEG during basic sedation and burst patterns during electroencephalic burst-suppression patterns (BSP) were analyzed. The aim of EEG analysis was the characterization and quantification of the interrelations between distinct frequency components in both states of sedation. The data for the investigations were derived from the routine EEG derivations of 12 patients with various neurosurgical diseases. It can be demonstrated that the degree of interrelation (amplitude modulation) between a low-frequency component (0-2.5 Hz) and oscillations with higher frequency (3-7.5 and 8-12 Hz) is increased in burst patterns during BSP compared with the EEG during basic sedation. It can be concluded that the degree of interrelations depends on the sedation depth induced by hypnotic drugs.

Adolescent↗
PubMed1999

New approaches for the detection and analysis of electroencephalographic burst-suppression patterns in patients under sedation.

An automatic EEG pattern detection unit was developed and tested for the recognition of burst-suppression periods and for the separation of burst from suppression patterns. The median, standard deviation and the 95% edge frequency were computed from single channels of the EEG within a moving window and completed by the continuous computation of frequency band power via an adapted Hilbert resonance filter. These parameters were given to the inputs of two hierarchically arranged artificial neural networks (NNs). The output signals of NNs indicate the suppression and burst phases. The burst recognition was focused on the precise recognition of the burst onset. In subsequent processing steps the time course of percentages of burst patterns within their corresponding burst-suppression-phases was calculated and the time locations of burst onsets can be used to trigger an averaging for a burst-related analysis. The data for our investigations were derived from the routine EEG derivations of 12 patients with various neurosurgical diseases. A group-related training of the NNs was realized. For the group-related trained NNs EEG data for 6 patients were used for training and the data of 6 other patients for testing the classification performance of the pattern recognition units. Additionally, the reliability of the detection algorithm was tested with data of two patients with convulsive state, resistant to treatment, and burst-suppression like pattern EEC.

Adolescent↗
PubMed1999

Dopexamine increases splanchnic blood flow but decreases gastric mucosal pH in severe septic patients treated with dobutamine.

OBJECTIVE: To assess the effects of dopexamine on splanchnic blood flow and splanchnic oxygen uptake in septic patients. DESIGN: A prospective, controlled trial. SETTING: A ten-bed intensive care unit (ICU) in a university hospital. PATIENTS: Twelve patients with severe sepsis (according to the criteria of the 1992 American College of Chest Physicians/Society of Critical Care Medicine consensus conference) being stabilized by volume loading and treated to an elevated oxygen delivery by dobutamine infusion. INTERVENTIONS: Infusion of increasing dosages of dopexamine (0.5, 1.0, 2.0, and 4.0 microg/kg/min). MEASUREMENTS AND MAIN RESULTS: Systemic and splanchnic hemodynamic and oxygen transport parameters as well as gastric mucosal pH (pHi) were measured. A hepatic venous catheter technique with indocyanine green dye dilution was used to determine splanchnic blood flow. Dopexamine increased global and splanchnic oxygen delivery without affecting oxygen consumption (VO2). Splanchnic blood flow increased proportionally to cardiac output, indicating that there was no selective effect of dopexamine on the splanchnic flow. Dopexamine decreased pHi in a dose-dependent fashion in all 12 patients. CONCLUSIONS: In hemodynamically stable, hyperdynamic septic patients being treated with dobutamine, dopexamine has no selective effect on splanchnic blood flow. In fact, a decreased pHi suggests a harmful effect on gastric mucosal perfusion.

Adult↗
PubMed1999

Adaptable preprocessing units and neural classification for the segmentation of EEG signals.

In this contribution, a methodology for the simultaneous adaptation of preprocessing units (PPUs) for feature extraction and of neural classifiers that can be used for time series classification is presented. The approach is based upon an extension of the backpropagation algorithm for the correction of the preprocessing parameters. In comparison with purely neural systems, the reduced input dimensionality improves the generalization capability and reduces the numerical effort. In comparison with PPUs with fixed parameters, the success of the adaptation is less sensitive to the choice of the parameters. The efficiency of the developed method is demonstrated via the use of quadratic filters with adaptable transmission bands as preprocessing units for the segmentation of two different types of discontinuous EEG: discontinuous neonatal EEG (burst-interburst segmentation) and EEG in deep stages of sedation (burst-suppression segmentation).

Coma↗
PubMed1998

Biodegradation of biphenyl by the ascomycetous yeast Debaryomyces vanrijiae.

Cells of the yeast strain Debaryomyces vanrijiae SBUG 770, grown with glucose, converted biphenyl to 4-hydroxybiphenyl as the major metabolite. In addition, 2-hydroxybiphenyl was formed in minor amounts. No further degradation of these substances was detected. However, these monohydroxylated derivatives were oxidised by alkane-grown cells in the presence of the co-metabolic substrate, tetradecane. Under these conditions 2-hydroxybiphenyl was oxidised to 2,5-dihydroxybiphenyl, and 4-hydroxybiphenyl was rapidly metabolised by formation of two major metabolites. One was identified as 3,4-dihydroxybiphenyl. Characterisation of the second product as 4-phenylmuconolactone points to a further metabolism of the initially formed dihydroxylated biphenyl via ortho-ring fission.

Ascomycota↗
PubMed1998

Isolation and characterization of a dibenzofuran-degrading yeast: identification of oxidation and ring cleavage products.

We characterized the ability of a yeast to cleave the aromatic structure of the dioxin-like compound dibenzofuran. The yeast strain was isolated from a dioxin-contaminated soil sample and identified as Trichosporon mucoides. During incubation of glucose-pregrown cells with dibenzofuran, six major metabolites were detected by high-performance liquid chromatography. The formation of four different monohydroxylated dibenzofurans was proven by comparison of analytical data (gas chromatography-mass spectrometry) with that for authentic standards. Further oxidation produced 2, 3-dihydroxydibenzofuran and its ring cleavage product 2-(1-carboxy methylidene)-2,3-dihydrobenzo[b]furanylidene glycolic acid, which were characterized by mass spectrometry and 1H nuclear magnetic resonance spectroscopy. These two metabolites are derived from 2-hydroxydibenzofuran and 3-hydroxydibenzofuran, as shown by incubation experiments using these monohydroxylated dibenzofurans as substrates.

Benzofurans↗
PubMed1997

The effects of low-dose dopamine on splanchnic blood flow and oxygen uptake in patients with septic shock.

OBJECTIVE: To assess the effects of low-dose dopamine on splanchnic blood flow and splanchnic oxygen uptake in patients with septic shock. DESIGN: Prospective, controlled trial. SETTING: University hospital intensive care unit. PATIENTS: 11 patients with septic shock, diagnosed according the criteria of the 1992 American College of Chest Physicians/Society of Critical Care Medicine consensus conference, who required treatment with norepinephrine. MEASUREMENTS AND MAIN RESULTS: Systemic and splanchnic hemodynamics and oxygen transport were measured before and during addition of low-dose dopamine (3 micrograms/kg per min). Low-dose dopamine and a marked effect on total body hemodynamics and oxygen transport. The fractional splanchnic flow at baseline ranged from 0.15 to 0.57. In 7 patients with a fractional splanchnic flow less than 0.30, low-dose dopamine increased splanchnic flow and splanchnic oxygen delivery and oxygen consumption. In 4 patients with a fractional splanchnic flow above 0.30, low-dose dopamine did not appear to change splanchnic blood flow. CONCLUSION: Low-dose dopamine has a potential beneficial effect on splanchnic blood flow and oxygen consumption in patients with septic shock, provided the fractional splanchnic flow is not already high before treatment.

Adult↗
PubMed1997

Epinephrine impairs splanchnic perfusion in septic shock.

OBJECTIVE: To assess the effects of epinephrine on splanchnic perfusion and splanchnic oxygen uptake in patients with septic shock. DESIGN: Prospective, controlled trial. SETTING: University hospital intensive care unit (ICU). PATIENTS: Eight patients with septic shock, according to the criteria of the 1992 American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference, requiring treatment with vasopressors. INTERVENTIONS: We compared in crossover design a 2-hr infusion of epinephrine with dobutamine plus norepinephrine in eight ICU patients with septic shock. Systemic and splanchnic hemodynamics and oxygen transport were measured before and during treatment with epinephrine. MEASUREMENTS AND MAIN RESULTS: There was essentially no effect of epinephrine on the global parameters, except for increased lactate concentrations. There were marked effects on the regional variables; epinephrine caused lower splanchnic flow and oxygen uptake, lower mucosal pH, and higher hepatic vein lactate. CONCLUSION: We conclude that undesirable splanchnic effects on patients in whom that region is particularly fragile should be considered when using epinephrine for septic shock treatment.

Adult↗
PubMed1996

Intercurrent complications in chronic alcoholic men admitted to the intensive care unit following trauma.

OBJECTIVE: A chronic alcoholic group following trauma was investigated to determine whether their ICU stay was longer than that of a non-alcoholic group and whether their intercurrent complication rate was increased. DESIGN: Prospective study. SETTING: An intensive care unit. PATIENTS: A total of 102 polytraumatized patients were transferred to the ICU after admission to the emergency room and after surgical treatment. Of these patients 69 were chronic alcoholics and 33 were allocated to the non-alcoholic group. The chronic-alcoholic group. met the DSM-III-R and ICD-10 criteria for alcohol dependence or chronic alcohol abuse/harmful use. The daily ethanol intake in these patients was > or = 60 g. Diagnostic indicators included an alcoholism-related questionnaire (CAGE), conventional laboratory markers and carbohydrate-deficient transferrin. MEASUREMENT AND RESULTS: Major intercurrent complications such as alcohol withdrawal syndrome (AWS), pneumonia, cardiac complications and bleeding disorders were documented and defined according to internationally accepted criteria. Patients did not differ significantly between groups regarding age, TRISS and APACHE score on admission. The rate of major intercurrent complications was 196% in the chronic alcoholic vs 70% in the non-alcoholic group (p = 0.0001). Because of the increased intercurrent complication rate, the ICU stay was significantly prolonged in the chronic-alcoholic group by a median period of 9 days. CONCLUSIONS: Chronic alcoholics are reported to have an increased risk of morbidity and mortality. However, to our knowledge, nothing is known about the morbidity and mortality of chronic alcoholics in intensive care units following trauma. Since chronic alcoholics in the ICU develop more major complications with a significantly prolonged ICU stay following trauma than non-alcoholics, it seems reasonable to intensify research to identify chronic alcoholics and to prevent alcohol-related complications.

Adolescent↗