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Biomedical subjects

T Heinrich

Publications and source records attributed to T Heinrich.

At least 19 recordsLinked to original sources
PubMed2001

Time-resolved spectroscopy of sulfur- and carboxy-substituted N-alkylphthalimides.

The photophysical and photochemical properties of N-phthaloyl-methionine (1), S-methyl-N-phthaloyl-cysteine methyl ester (2) and N-phthaloyltranexamic acid (3) were studied by time-resolved UV/Vis spectroscopy, using laser pulses at 248 or 308 nm. The quantum yield of fluorescence is low (phi(f)< 10(-2)) for 1-3 in fluid and glassy media, whereas that of phosphorescence is large (0.3-0.5) in ethanol at - 196 degrees C. The triplet properties were examined in several solvents, at room temperature and below. The spectra and decay kinetics are similar, but the population of the pi(pi*) triplet state, as measured by T-T absorption, is much lower for 1 and 2 than for 3 or N-methyltrimellitimide (5') at ambient temperatures. The quantum yield (phi(delta)) of singlet molecular oxygen O2(1deltag) formation is substantial for 3 and 5' in several air- or oxygen-saturated solvents at room temperature, but small for 2 and 1. The quantum yield of decomposition is substantial (0.2-0.5) for 3 and small (<0.05) for 2 and 1. It is postulated that photoinduced charge separation in the spectroscopically undetectable 3n,pi* state may account for the cyclization products of 1 and 2. In aqueous solution, this also applies for 3, whereas in organic solvents cyclization involves mainly the lower lying 3pi,(pi*) state. Triplet acetone, acetophenone and xanthone are quenched by 1-3 in acetonitrile; the rate constant is close to the diffusion-controlled limit, but smaller for benzophenone. While the energy transfer from the triplet ketone occurs for 3, a major contribution of electron transfer to the N-phthalimide derivative is suggested for 1 and 2, where the radical anion of benzophenone or 4-carboxybenzophenone is observed in alkaline aqueous solution.

Journal Article↗
PubMed2001

[Company approaches concerning workers with performance alterations or disablement: interview findings on the perspectives of the various parties involved].

This paper provides information about the research programme "In-plant interventions in the German car industry to increase job opportunities for employees with (severe) disabilities". The research was done in 2000 by the University of Trier and the International Research Unit for Work and Social Integration (IFASI). The purpose of the study was to capture, document, and analyse internal practices of occupational rehabilitation in five German car factories. Taking a qualitative approach, 23 persons of different company areas were interviewed, and numerous documents were analysed. The article reflects applied disability management strategies and points out success factors and barriers of inclusion.

Adult↗
PubMed2000

Treatment outcome for a maltreated population: benefits, procedural decisions, and challenges.

OBJECTIVE: To review the benefits, challenges, and procedural decisions to consider when implementing and managing a treatment outcome program for a maltreated population. METHOD: We reviewed the reasons to implement a treatment outcome program, decisions regarding procedures, and challenges likely to be encountered based on literature in the field and the authors' 6 years of experience in developing and maintaining an outcome program at a center specializing in the treatment of maltreated children. RESULTS: The development of an outcome programs requires careful measurement selection, early and ongoing staff-involvement, support from higher management, a well-developed data base and client tracking system, a coordinator and support staff, clinical utility, planning for fiscal impact, and flexibility to contend with challenges. CONCLUSIONS: Based on our experience, the plethora of clinically rich and administratively useful information derived from an outcome program far outweighs the challenges and costs of establishing and maintaining an outcome program.

Child↗
PubMed1999

Reduced oxidative stress during acellular reperfusion of the rat liver after hypothermic oscillating perfusion.

BACKGROUND: ATP resynthesis during reperfusion after liver preservation has been shown to be well correlated with the function of transplanted grafts. Nevertheless, the advantages of a cellular energy charge loading during the preservation period are yet not fully understood. This study evaluates the effects of different nucleotide levels at the end of preservation on metabolic changes and oxidative stress during reperfusion. METHODS: Two experimental groups were chosen reflecting different energy charge states after preservation: static cold storage for 10 hr and hypothermic oxygenated oscillating perfusion for 10 hr. In both experimental groups, normothermic ex vivo acellular reperfusion over 40 min was performed. A third group consisted of nonpreserved livers similarly reperfused for 40 min. Superoxide formation was detected by the superoxide dismutase inhibitable reduction of ferricytochrome c added to the normothermic perfusate. RESULTS: Superoxide formation and lipid peroxidation malondialdehyde were significantly lower during reperfusion after the energy charge loading before reperfusion by the hypothermic oscillating perfusion technique. However, oxygen radical formation, liver cell injury (lactate dehydrogenase [LDH] release), and TNFalpha release were significantly higher in energy charge-depleted groups (nonpreserved and cold stored livers). CONCLUSIONS: Hypothermic oscillating oxygenated perfusion led to the elevated energy charge during preservation and led to reduced oxygen radical formation as well as less lipid peroxidation during reperfusion, in contrast to cold stored livers and nonpreserved livers. This suggests a correlation between the energy charge before reperfusion and oxygen radical formation as well as liver injury at reperfusion.

Animals↗
PubMed1999

Hypervascular spinal tumors: influence of the embolization technique on perioperative hemorrhage.

BACKGROUND AND PURPOSE: Corporectomy is an effective treatment for vertebral metastases; however, massive perioperative hemorrhage is often associated with this procedure. We compared preoperative particle, particle-coil, and coil embolizations of hypervascular spinal tumors prior to vertebral body replacement to determine which prevented perioperative hemorrhage most effectively. METHODS: The vertebral tumors of 59 patients were embolized prior to corporectomy. In 26 cases, only coils were used for the proximal occlusion of feeding segmental arteries. Twenty-four patients received a combination of polyvinyl alcohol (PVA) particles and coils, and nine tumors were embolized with particles alone. We compared intraoperative blood loss between the three groups and 10 other patients who did not undergo embolization prior to corporectomy. RESULTS: Estimation of intraoperative hemorrhage showed a median value of 4350 mL in patients without embolization, 2650 mL in cases of coil embolization, 1850 mL in cases of particle-coil embolization, and 1800 mL in cases of particle embolization. The difference between unembolized patients and those who underwent coil embolization was not statistically significant. Particle and particle-coil embolizations showed very similar results, and reduced hemorrhage significantly as compared to unembolized and proximal coil occlusion cases. Residual bleeding came from the venous system and the neighborhood of the embolized region. CONCLUSION: Particle embolization prior to corporectomy can reduce perioperative hemorrhage. The additional benefit of proximal coil occlusion of arterial feeders is questionable.

Adolescent↗
PubMed1998

Rat liver preservation by hypothermic oscillating liver perfusion compared to simple cold storage.

Rat livers were preserved hypothermically for 10 or 24 h in vitro as if for transplantation. Two methods of preservation were compared using physiological and biochemical parameters: simple storage and oscillating perfusion. By measuring the nucleotides after preservation the calculated energy charge was significantly higher after 10 and 24 h of oscillating perfusion compared to the simple storage group. In addition, a significant energy charge loading was demonstrated by 10 h oscillating perfusion compared to the initial value prior to perfusion. The oscillating, computer-controlled perfusion permits continuous monitoring of perfusate temperature, O2 consumption, pCO2, portal vein pressure, and pH and also automatic sample collection and pH compensation. In addition, the perfusate can be easily exchanged by using two different pumps or be rewarmed by a heat exchanger. For measuring of short-lived metabolites (interleukins, oxygen radicals, prostaglandins) sampling can be performed directly out of the vena cava outflow. pH and temperature stability was maintained by a data acquisition and controlling system. Because of a special designed liver chamber a combination of storage and perfusion with or without substrates was possible. The demonstrated standardized perfusion technique was achieved by a combination of special equipment and computer-aided monitoring and allows further experiments to improve understanding of ischemic and reperfusion injury.

Adenine Nucleotides↗
PubMed1998

Hypothermic oscillating liver perfusion stimulates ATP synthesis prior to transplantation.

BACKGROUND: ATP and glycogen depletion often have been demonstrated during cold storage of the liver prior to transplantation. Suppression of events that lead to metabolic depression and to lipid peroxidation could contribute to improvement of liver preservation. A new method of liver preservation for transplantation is therefore suggested, an oscillating oxygenated hypothermic liver perfusion. METHODS: Biochemical analysis of liver tissue samples and perfusate after 10 h of perfusion by the presented oscillating perfusion model were compared with results after continuous liver perfusion for 10 h as well as with data derived from cold-stored livers over a period of 10 h. Particular reference was made to nucleotide metabolites, glycogen content, lipid peroxidation, glutathione content, glycolytic metabolites, and enzyme release before and after preservation. RESULTS: Glycogen depletion occurred to the same degree in hypothermic storage and machine perfusion (oscillating as well as continuous perfusion), but the energy charge was significantly increased after oxygenated perfusion, whereas cold storage resulted in a significant energy charge depletion. In addition, perfusion by an oscillating technique yielded superior energy charge loading compared to the continuous perfusion technique and diminished the other hand lipid peroxidation. CONCLUSIONS: Hypothermic oscillating oxygenated perfusion could be important for the improvement of the quality of energy-depleted organs prior to transplantation.

Adenosine↗
PubMed1997

Subtractive hybridization of cDNA from small amounts of plant tissue.

A subtractive hybridization method is described that allows the generation of a subtractive gene library from small amounts of plant or other eukaryotic tissues. The method uses paramagnetic oligo-dT beads to capture poly-adenylated mRNA and to synthesize the complementary cDNA on a solid support. The use of magnetic beads facilitates the change of reaction buffers and the removal of primers and minimizes yield losses. Subtracted material obtained from this method can either be cloned directly or used to screen a specific library.

DNA, Complementary↗
PubMed1995

Point mutations in the leader boxA of a plasmid-encoded Escherichia coli rrnB operon cause defective antitermination in vivo.

We have introduced point mutations into the leader boxA of a plasmid-encoded Escherichia coli rrnB operon to study the in vivo role of this regulatory element in the natural context of rRNA synthesis. The same mutations were previously shown to cause severe antitermination defects in vitro and in the context of a reporter gene assay. The plasmid-encoded rrnB mutant constructs studied here also contained point mutations in the 16S and 23S rRNA genes, which were used to distinguish rRNAs derived from plasmid and chromosomal rrn operons by primer extension analysis. Point mutations in boxA reduced the fraction of plasmid-derived rRNA in the cell from 75% to about 50%. The reduction was similar for both 30S and 50S subunits as well as 70S ribosomes, suggesting that no transcriptional polarity occurred between the expression of the 16S and 23S rRNA genes in plasmid rrnB operons carrying a mutant boxA. The boxA mutations do not affect the amount of transcription initiation, suggesting that a suboptimal leader boxA causes premature transcription termination at an early stage of transcription. Our results are consistent with a role for antitermination in the completion of full-length rrn transcripts but give no indications of posttranscriptional boxA functions.

Base Sequence↗
PubMed1994

A double-blind comparison of amitriptylinoxide versus doxepine in the treatment of severe depression.

In a double-blind parallel group study the efficacy and safety of amitriptylinoxide were evaluated vs. doxepine in the treatment of in-patients with severe depression. Two groups of 22 patients each received amitriptylinoxide and doxepine respectively at a daily dosage of 120-360 mg for a period of 4 weeks. The total score on the Hamilton Depression Scale (HAMD) was reduced with amitriptylinoxide on an average from 28 +/- 5 before treatment to 12 +/- 8 at the end of treatment, with doxepine from 29 +/- 8 to 13 +/- 11. Of the amitriptylinoxide-treated patients, 12 showed a more than 50% reduction in this score compared with 15 under doxepine. The difference was not statistically significant. Twenty patients in each group experienced adverse drug reactions, the percentage of anticholinergic side effects being equal in the two groups.

Adult↗
PubMed1994

[Astigmatism against the rule after small incision cataract surgery. A multifactorial, multivariate study].

BACKGROUND: Small-incision cataract surgery has been further developed by the introduction of the sutureless technique. This procedure has reduced operation time and the surgically induced astigmatism compared to closure technique. PATIENTS AND METHODS: We evaluated 426 patients operated by the same surgeon using the same intraoperative approach. Patients were monitored for postoperative induced astigmatism and postoperative complications. RESULTS: Our results demonstrated small induced astigmatism after one week and one month. The no-stitch technique showed the smallest postoperative astigmatism with the least variation. With multivariate methods we also analysed several factors influencing the axis of the induced astigmatism. CONCLUSION: The most important factor for a postoperative astigmatism against the rule is using the no-stitch-technique and the existence of a preoperative astigmatism against the rule.

Astigmatism↗
PubMed1993

Sequence of the gene encoding ribosomal protein L11 from Thermus thermophilus HB8.

The complete nucleotide sequence of the gene encoding ribosomal protein L11 from the extreme thermophilic eubacterium, Thermus thermophilus HB8, was determined. L11 amino acid (aa) sequences from mesophilic and halophilic organisms, as well as from another thermophiles, were compared with the T. thermophilus L11 aa sequence.

Amino Acid Sequence↗
PubMed1992

[Epiretinal membrane formation after pars plana vitrectomy in proliferative diabetic retinopathy].

Recurrent epiretinal membranes are a major contributing factor to functional and visual failures after pars plana vitrectomy for proliferative vitreoretinal disorders. In this study 222 consecutive eyes that have had pars plana vitrectomy for proliferative diabetic retinopathy (operated in 1986 und 1987) were evaluated retrospectively. The study focuses on a subgroup of 108 consecutive eyes all with preoperative tractional retinal detachment and all operated with primary silicone oil injection. A minimum follow up of six months was present in 90% of these cases. Permanent visual success was observed in 40% of the eyes, most of which had dense vitreous hemorrhage preoperatively. Multivariant analysis revealed that among several potential risk factors recurrent epiretinal membranes as well as silicone oil were significantly associated with visual failure. Because of the high incidence of recurrent epiretinal membranes associated with poor functional results silicone oil injection following pars plana vitrectomy should be employed restrictively in patients with proliferative diabetic retinopathy.

Cataract↗
PubMed1992

[Importance of standardized photos for planimetry].

In a series of 30 patients we compared the optic disc measurements. Disc photographs were either taken centric or excentric. Pictures with excentric discs showed significantly smaller measurements. However, the C/D-ratio demonstrated a good correlation (r = 0.95). For follow-up studies even not standardized photos can be useful, especially if the same examinator makes all the measurements.

Fluorescein Angiography↗
PubMed1992

[Results of conventional detachment surgery. I. Study planning, patients and vision results].

A consecutive series of patients with retinal detachment were examined. All patients were treated primarily with buckling procedure. Patients with redetachment, bilateral detachment, vitrectomy or history of strabismus or amblyopia were excluded. Of these 155 patients, 117 could be examined. 97% of patients without macula detachment are able to keep or improve their visual acuity. 85% of those patients with macula detachment showed an improvement of visual acuity. The most important prognostic factor for the visual outcome is the duration of macula detachment. In cases of more than four days duration a visual acuity of 20/40 or more could not be expected.

Adolescent↗