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T Becker

Publications and source records attributed to T Becker.

At least 37 records · Page 2Linked to original sources
PubMed1993

An automatic dehydrogenase-based flow-injection system: application for the continuous determination of glucose and lactate in mammalian cell-cultures.

A concept for the development of an automatic flow-injection analyzer with integrated dehydrogenase columns and its application in the control of industrial processes is presented. The system is based upon a kernel consisting of a nested-loop injection unit, pumps for the filling of the injection loops and the transport of buffer and values for switching on the one hand between sample and standard solutions and on the other hand between different enzyme columns. A Microsoft Windows 3.x application 'WIN-FIA' controls interactively the whole system and can be easily adapted to a specific solution of an analytical problem. As an example, the flow-injection system was used for the continuous determination of glucose and lactate, using glucose dehydrogenase (GDH) and lactate dehydrogenase (LDH) as indicator enzymes, in a mammalian cell-culture fermentation process. The resulting concentration values are in good agreement with those obtained by discontinuously taken standard spectrophotometric enzyme assays.

Animals↗
PubMed1992

S100P, a novel Ca(2+)-binding protein from human placenta. cDNA cloning, recombinant protein expression and Ca2+ binding properties.

A novel member of the S100 protein family, present in human placenta, has been characterized by protein sequencing, cDNA cloning, and analysis of Ca(2+)-binding properties. Since the placenta protein of 95 amino acid residues shares about 50% sequence identity with the brain S100 proteins alpha and beta, we proposed the name S100P. The cDNA was expressed in Escherichia coli and recombinant S100P was purified in high yield. S100P is a homodimer and has two functional EF hands/polypeptide chain. The low-affinity site (Kd = 800 microM), which, in analogy to S100 beta, seems to involve the N-terminal EF hand, can be followed by the Ca(2+)-dependent decrease in tyrosine fluorescence. The high-affinity site, provided by the C-terminal EF hand, influences the reactivity of the sole cysteine which is located in the C-terminal extension (Cys85). Binding to the high-affinity site (Kd = 1.6 microM) can be monitored by fluorescence spectroscopy of S100P labelled at Cys85 with 6-proprionyl-2-dimethylaminonaphthalene (Prodan). The Prodan fluorescence shows a Ca(2+)-dependent red shift of the maximum emission wavelength from 485 nm to 502 nm, which is accompanied by an approximately twofold loss in integrated fluorescence intensity. This indicates that Cys85 becomes more exposed to the solvent in Ca(2+)-bound S100P, making this region of the molecule, the so-called C-terminal extension, an ideal candidate for a putative Ca(2+)-dependent interaction with a cellular target. In p11, a different member of the S100 family, the C-terminal extension which contains a corresponding cysteine (Cys82 in p11), is involved in a Ca(2+)-independent complex formation with the protein ligand annexin II. The combined results support the hypothesis that S100 proteins interact in general with their targets after a Ca(2+)-dependent conformational change which involves hydrophobic residues of the C-terminal extension.

Amino Acid Sequence↗
PubMed1992

Protein-protein interaction studied by site-directed mutagenesis. Characterization of the annexin II-binding site on p11, a member of the S100 protein family.

p11, a member of the S100 protein family, forms a stable heterotetrameric complex with annexin II. The p11-binding site of annexin II resides in the N-terminal 14 residues, which form an amphiphatic alpha-helix with the hydrophobic face representing the contact site for p11 (Johnsson, N., Marriott, G., and Weber, K. (1988) EMBO J. 7, 2435-2442). We show that a corresponding peptide can be used to purify recombinant p11 by affinity chromatography. To map the annexin II-binding site on p11, we have produced progressively truncated p11 derivatives by site-directed mutagenesis. Our analysis reveals that a highly hydrophobic region between residues 85 and 91 is indispensable for annexin II-binding. It is located in the C-terminal extension, following the second distorted EF-hand. Using a series of single amino acid replacements, we have identified individual hydrophobic residues, which seem to represent contact points for annexin II. Most notably, substitution of tyrosine 85 or phenylalanine 86 by alanine drastically reduces the affinity of p11 for annexin II, whereas replacement of these residues by tryptophan has no or only a marginal effect. Thus, hydrophobic side chains on both annexin II and p11 are involved in complex formation.

Amino Acid Sequence↗
PubMed1992

Neurological long-term follow-up in left atrial myxoma: are late complications frequent or rare?

Neurological manifestations were analysed in 13 patients with left atrial myxoma confirmed by histological study. In this group, 6 patients had neurological complaints at initial presentation, 5 had cardiac symptoms, and 4 patients presented with signs of systemic disease. CT was performed in 10 and MRI in 7 patients. There were signs of ischaemic or haemorrhagic infarction (6 of 12) and one lesion suggestive of myxoma metastasis; other findings mainly comprised non-specific white matter lesions revealed by MRI. Neurological follow-up 0.5-8 years after tumour resection revealed no delayed neurological complications, follow-up CT and MRI findings were not suggestive of lesions acquired after operation. It is suggested that this rare condition of cardiac myxoma should be suspected in young patients with CNS symptoms or signs lacking cerebrovascular or cardiovascular risk factors and should be included in the differential diagnosis of vasculitis. With timely diagnosis and resection of the cardiac tumour the long-term prognosis can be considered improved.

Adult↗
PubMed1992

MRI white matter hyperintensity in neuroleptic malignant syndrome (NMS)--a clue to pathogenesis?

The case of a young female patient with neuroleptic malignant syndrome (NMS) and extended MRI white matter hyperintensity in the left parietal and both occipital lobes is reported. MRI lesions resembled findings in hypertensive encephalopathy, they were not readily compatible with CNS vasculitis. Venous sinus thrombosis could be ruled out. Vascular encephalopathy with transient white matter edema and a small residual left parietal lesion is suggested. Neurochemical implications are discussed with particular reference to a possible involvement of excitatory amino acids in NMS pathogenesis.

Adult↗
PubMed1992

Post partum blues: depressive disease or pseudoneurasthenic syndrome.

Depressive mood disorders following childbirth can be quantified with self-rating and observer-rating scales. During two months, in the period from November 1989 to March 1990, women admitted to the obstetric unit of the University of Würzburg were examined on days 3 and 5 post-partum with the Hamilton Psychiatric Rating Scale for Depression, the Montgomery-Asberg-Depression-Rating-Scale and the Befindlichkeits-Scale by von Zerssen. Results reveal that during the early puerperium, scores on these scales rarely reach the same severity as in major depressive disorder. The clinical picture is no different from emotional-hyperaesthetic hyposthenia following other kinds of physical illness such as endocrine disorders.

Adult↗
PubMed1992

[Remission of schizophreniform psychosis after brain tumor surgery].

A 19-year-old female was admitted to hospital due to a schizophrenia-like psychosis of the paranoid type including delusions and various hallucinations. Neurologically she only showed tics of the eyebrows with increased eye blinking. 30 months before an astrocytoma located on the left basal temporal lobe had been resected after the patient suffered from several psychomotor and two grand mal seizures. Following post-operative anticonvulsant therapy seizures had completely disappeared and the patient had been free of symptoms of any kind. After the acute onset of the psychosis another follow-up MRI of the brain using coronary sections revealed a small relapse-tumor. Symptoms disappeared after high-dose neuroleptic therapy. Finally another surgical intervention led to a lasting remission of the psychotic symptomatology (so far 18 months). Postoperatively neuroleptics could be discontinued. Clinical picture and MRI findings will be discussed with a focus on possible etiological factors in schizophrenia.

Adult↗
PubMed1991

Cell migration along glial fibers in dissociated cell culture of the frog optic tectum.

Migration of neurons along radial glial fibers is associated with the development of laminated regions in the mammalian brain. We examined cell interactions in dissociated cell cultures of the frog optic tectum, which is well laminated. Using time-lapse photography, we observed active migration of neuron-like cells along strands of radial glia-like cells, which were identified by indirect immunocytochemical staining of the glial fibrillary acidic protein. The migration patterns we observed in our cultures are strikingly similar to those found in mammalian cultures. We hypothesize that this type of neuron-glia interaction is involved in the constitution of laminae in the frog optic tectum.

Animals↗
PubMed1991

Do arachnoid cysts grow? A retrospective CT volumetric study.

The volumes of intracranial arachnoid cysts were measured in 136 CT scans of 86 patients. Absolute and relative cyst size was calculated. Left hemisphere and middle cranial fossa location prevailed. A slight negative correlation of relative cyst size with age (r = -0.21, NS) disappeared when analysis was restricted to the adult age group (greater than or equal to 20 years). After the sample was divided into two groups according to relative cyst size (cysts less than mean volume vs cysts greater than mean volume), small AC showed no correlation with age, while large AC correlated positively with age (r = 0.79, P less than 0.05). A subgroup of large AC appears to expand with time, while the majority of small AC remain unchanged.

Adolescent↗
PubMed1991

Interaction of gut and liver in nitrogen metabolism during exercise.

The role of the gut and liver in nitrogen metabolism was studied during rest, 150 minutes of moderate-intensity treadmill exercise, and 90 minutes of recovery in 18 hour-fasted dogs (n = 6). Dogs underwent surgery 16 days before an experiment for implantation of catheters in a carotid artery and in the portal and hepatic veins, and Doppler flow cuffs on the hepatic artery and portal vein. Arterial glutamine, alanine, and alpha-amino nitrogen (AAN) levels decreased gradually with exercise (P less than .05), while arterial glutamate, NH3, and urea were unchanged. Net gut glutamine uptake was 1.3 +/- 0.5 mumol/kg.min at rest, and increased transiently to 2.5 +/- 0.3 mumol/kg.min at 60 minutes of exercise (P less than .05) as gut extraction increased. Net hepatic glutamine uptake was 0.6 +/- 0.4 mumol/kg.min at rest, and increased to 3.4 +/- 0.6 and 2.6 +/- 0.5 mumol/kg.min after 60 and 150 minutes of exercise (P less than .05) as hepatic extraction increased. Net gut glutamate and NH3 output both increased transiently with exercise (P less than .05). These increases were matched by parallel increments in the net hepatic uptakes of these compounds. Alanine output by the gut and uptake by the liver were unchanged with exercise. Net gut AAN output was -2.1 +/- 1.8 mumol/kg.min at rest (uptake occurred), and increased transiently to 11.2 +/- 3.5 mumol/kg.min after 30 minutes of exercise (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Alanine↗
PubMed1991

Distribution of substance P, GnRH, Met-enkephalin in the central nervous system of the pig.

The distribution of substance P (SP), gonadotropin releasing hormone (GnRH) and Met-enkephalin in the brain and spinal cord of the domestic pig is described for the first time. The levels of SP, GnRH and Met-enkephalin were measured by specific radioimmunoassays in various regions of the brain and spinal cord of the pig. Substance P and Met-enkephalin are widely distributed within the central nervous system of the pig. High levels of SP were found in the preoptic area (POA), suprachiasmatic area (SCA), medial basal hypothalamus (MBH) and brain stem while moderate amounts of SP were found in olfactory bulb (OB). High levels of Met-enkephalin were found in POA, SCA and MBH, and moderate levels of Met-enkephalin in OB and brain stem. Both SP and Met-enkephalin levels were higher in the dorsal spinal cord in comparison with the levels of these peptides in the ventral spinal cord. This finding is in agreement with the predominant role played by these neural systems in primary afferent mediation of nociceptive impulses. The POA and SCA contained only low levels of GnRH while the MBH contained high levels of GnRH. Finally, some differences in the quantitative distribution of these peptides in the pig and rat are discussed.

Animals↗
PubMed1991

Moving targets: bicycle-related injuries and helmet use among university students.

We conducted a cross-sectional study to evaluate bicycling habits and helmet use in a sample of university students in a southwestern state university. Thirty-one of 100 students in our sample owned bicycle helmets; of these, 17 (54.8%) wore helmets during most (more than three fourths) of their bicycle trips. Almost half of the students reported that more than 25% of their bicycling was done in heavy traffic but they rarely used bicycle trails. Sixty-five students in the sample had sustained at least one minor injury during the previous 5 years, and 18 had been hospitalized as a result of bicycle-related injuries. We found no substantial differences between male and female subjects in bicycle-related hospitalizations, although male subjects were more likely to sustain minor injuries than were females. Helmet ownership was most strongly associated with previous injury experience, especially hospitalization resulting from bicycling injuries (OR = 3.6; 95% CI = 1.3, 10.1). We also observed an association between helmet ownership and possession of insurance coverage for bicycling injuries (OR = 3.0; 95% CI = 1.2, 7.6). Ethnicity was a factor in helmet ownership--helmets were owned by 26 of 69 (37.7%) of non-Hispanic whites, in contrast to 1 of 24 (4.2%) of all other ethnic groups combined. Our survey data suggest that perceived risk is an important factor in bicyclists' use of safety helmets.

Adolescent↗
PubMed1991

Thyroid and ovarian function in infertile women.

The aim of this study was to examine more closely the interaction between thyroid function and pituitary--ovarian axis in infertile women. In 185 infertile women without clinical signs of thyroid dysfunction, TRH-tests (TSH basal and 30 min after 200 micrograms TRH i.v.) were performed in the early follicular phase in addition to routine hormonal checks (gonadotrophins, oestradiol, DHEAS, testosterone, prolactin). The women were classified as euthyroid (n = 74; TSH stim 5-20 mU/l), latent hyperthyroid (n = 31; TSH stim less than 5 mU/l), and preclinical hypothyroid (n = 80; TSH stim greater than 20 mU/l). From frozen serum, the following determinations were performed: TSH IRMA, laevothyroxine (T4), thyroxine binding globulin (TBG), microsomal (Mab) and thyroglobulin (Tab) antibodies. Various correlations between the thyroid parameters and the pituitary--ovarian axis were demonstrated. With increasing TBG concentrations, the interval between menses decreased. Overall and spontaneous pregnancy rates were highest in women with normal (less than 75th perc.) basal and stimulated TSH, high (greater than 75th perc.) T4 and low (less than 25th perc.) Mab. Women with normal Tab or high TBG experienced the highest delivery rate (77 versus 30%), while in women with low Tab or high Mab abortion and tubal pregnancies were most frequent. As only 25 women exhibited elevated Mab (greater than 500 U/ml) or Tab (greater than 200 U/ml) which correlated with elevated TSH and normal T4, the routine determination of thyroid antibodies was not necessary. The TRH-test, however, should be included in infertility work-up.

Female↗
PubMed1991

[Study of traffic aptitude in relation to dental interventions].

Applying a video game the traffic aptitude of patients was investigated before and after dental surgical treatment and local anesthesia. Local anesthesia or operative removal of impacted third molars does not reduce the psychophysical performance important for driving a car if there is no influence of other factors. The consequences of the obtained results are discussed even under forensic aspects.

Anesthesia, Dental↗
PubMed1990

Effect of early exposure to delta-9-tetrahydrocannabinol on the levels of opioid peptides, gonadotropin-releasing hormone and substance P in the adult male rat brain.

The effects of neonatal exposure to delta-9-tetrahydrocannabinol (THC) on the adult animal brain neurochemistry and pain perception were evaluated. Newborn rat pups were culled to a litter size of 8 (males and females) and treated either with THC (2 mg/kg) or oil (control) daily, during days 1-4 after birth. After weaning, the THC-treated males were housed 4 per cage. During the juvenile period (day 50), the THC-treated animals exhibited significantly lower baseline tail-flick values (a measure of pain perception) than the control. However, as adults, the THC-treated animals exhibited significantly higher sensitivity to pain following 5 mg/kg morphine challenge. Furthermore, the THC-treated animals had significantly elevated beta-endorphin and methionine-enkephalin levels in almost all the brain areas sampled for the study. In addition, the neonatally THC-treated rats exhibited significantly higher levels of substance P (SP) and significantly lower levels of gonadotropin releasing hormone (GnRH) in the anterior hypothalamus-preoptic area. The SP and GnRH levels did not differ among the THC-treated and control animals in the medial basal hypothalamus. The results of this study indicate that even a very low dose of THC administered during the neonatal period has a long-lasting effect on the brain neurochemistry. In particular, neonatal administration of THC appears to alter functioning of the endogenous opioid system.

Animals↗