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Biomedical subjects

J Lehmann

Publications and source records attributed to J Lehmann.

At least 181 records · Page 10Linked to original sources
PubMed1992

Differences in mental task performance and slow potential shifts in subjects differing in cortisol level.

Hormones of the pituitary-adrenocortical axis (e.g., cortisol) are involved in the regulation of brain function. This study was aimed to clarify whether individual differences in baselines of cortisol are related to differences in heart rate (HR), slow brain potential shifts (SPS), performance data and personality. 17 males were instructed to solve 120 arithmetical tasks under time stress conditions. They could obtain monetary bonuses according to the accuracy of their task performance. This test condition was compared to a control condition. To determine the plasma level of cortisol by radioimmunoassays four blood samples were collected during the session. Baselines were estimated twice. A clustering procedure with respect to all cortisol levels resulted in a group of high responders (HC, n = 9) and a group of low responders (LC, n = 8). The HR was significantly higher in the HC group. The SPS of the LC group were characterized by a larger P300 elicited by the task followed by a steep negative slow wave (NSW) as compared to the HC group. LC subjects also showed a higher NSW before feedback presentation. The LC group solved the tasks faster and obtained more than twice the reward than the other group. They scored higher in achievement motivation and also reported increased 'Social Acceptance' and decreased 'Tiredness'. In sum, the results suggest a more efficient regulation of the arousal level of the LC group in contrast to the HC group as far as reflected in the parameters analysed.

Adolescent↗
PubMed1992

[Malignant tumor of the autonomic nervous system of the stomach (GAN-tumor)--case report of a new entity].

Gastrointestinal autonomic nerve (GAN)-tumors are extremely rare. So far seven cases of intestinal and four of gastric GAN-tumors were reported. GAN-tumors, also termed plexosarcomas, arise from autonomic nervous system plexuses of the gastrointestinal tract such as those of Meissner or Auerbach. We report a case of a metastatic gastric GAN-tumor in a 40-year-old woman. A small, 1 cm in diameter, submucosal plexosarcoma located in the posterior gastric wall and a 1.5 kg, 23 x 15 x 11-cm metastasis located retroperitoneally behind the stomach between liver, spleen and pancreas without discernable invasion of any of these organs were found. En-bloc resection of the retroperitoneal mass, the spleen, the pancreatic tail, and a part of the posterior gastric wall adhering to the mass were performed. In addition, lymph node metastases in splenic hilum were noted, and resected. In CT scan liver metastases were detectable fourteen months after surgery. The diagnosis is based on light microscopical, ultrastructural, and immunhistochemical analyses. The prognosis of GAN-tumors is fatal. In spite of radical excision 8 of 11 reported patients died few month after surgery while local recurrences and/or metastases in regional lymph nodes and in the liver were found. The response to chemotherapy was poor.

Adult↗
PubMed1992

[An intermediate, generalized form of neuroaxonal dystrophy--light- and electron microscopic findings].

This report concerns a 11-year-old girl--at the time of death--who developed normally until the age of 2 years when further psychomotoric maturation stopped and then regressed. The disease was diagnosed as neuroaxonal dystrophy (NAD) by sural nerve biopsy at the age of 7. Further course was characterized by complete loss of all motoric and sensory functions and dementia as well. Finally there was decerebration. The autopsy revealed generalized NAD associated with pallidal deposition of iron pigment to classify as generalized intermediate NAD type II according to Gilman and Barrett (1973). The main histological findings were axonal swellings and spheroids consisting ultrastructurally of membrano-tubular profiles, lamellar structures, vacuoles, glycogen granules and mitochondrial aggregates. Immunohistologically there was partial positive expression of synaptophysin and neurofilament protein in the spheroids. Firstly described electron microscopical findings in the retina include the typical axonal lesions largely in interior layers. Photoreceptors and their synaptic contacts were preserved. The present blindness is of the neuronal type. The current etiopathogenetic opinions, aspects of bioptic diagnosis and problems of classification of primary NADs are discussed.

Axons↗
PubMed1991

The stepwise degradation of a glycosylated aldose. A potential method for sequencing branched oligosaccharides.

2,3,6,2',3',4',6'-Hepta-O-methylmaltose diethyl dithioacetal (2), obtained under mild conditions from N-methyl-hepta-O-methyl-N-p-nitrophenyl-beta-maltosylamine (1), was converted into the disulfone 4. Storage of a solution of 4 in aqueous tetrahydrofuran gave 1,2-dideoxy-1,1-bis(ethylsulfonyl)hepta-O-methylmalt-1-en itol (5). Fragmentation of 5 with aqueous ammonia released 2,3,4,6-tetra-O-methyl-D-glucose. The degradation procedure has potential for the sequencing of branched oligosaccharides.

Carbohydrate Sequence↗
PubMed1991

A bireactant, irreversible, active-site-directed inhibitor of beta-D-galactosidase (Escherichia coli). Synthesis and properties of (1/2,5,6)-2-(3-azibutylthio)-5,6-epoxy-3-cyclohexen-1-ol.

(1/2,5,6)-2-(3-Azibutylthio)-5,6-epoxy-3-cyclohexen-1-ol (1) was synthesized and was found to irreversibly inactivate beta-D-galactosidase (Escherichia coli). The inactivation was prevented by the presence of isopropyl 1-thio-beta-D-galactopyranoside (IPTG). The vinyloxirane group of 1 reacted with water and other nucleophiles, especially at higher pH values. Reaction of 1 with beta-D-galactosidase was slow enough so that a competitive-inhibition constant (Ki) of 29mM could be determined. The inhibition constant for (1,2/3,6)-6-(3-azibutylthio)-2-bromo-4-cyclohexene-1,3-diol (2), the precursor of the bireactant inhibitor 1, was 13 mM, while that of (1,3/2,4)-3-(3-azibutylthio)-5-cyclohexene-1,2,4-triol (3), the product formed when the reactant is allowed to react with water, was 23mM. After irradiation by light, beta-D-galactosidase that had initially been treated with the bireactant compound and then digested with trypsin, showed a new pattern of elution from h.p.l.c., indicating that there was reaction at two regions of the beta-D-galactosidase molecule.

Azo Compounds↗
PubMed1991

The medium cycle bioreactor (MCB): monoclonal antibody production in a new economic production system.

The perfusion mode of a continuous cell culture bioreactor was modified to establish a closed loop system. Eighty percent of the spent medium was re-used twice. The medium cycle bioreactor unit was operated sterile and uncomplicated without a technical retention system for the high molecular weight substances. Therefore, only 20% of the actual medium was necessary to run the recycling process. During seven days culture time in a two liter scale 5 grams of IgG1 type monoclonal antibody was produced. During that period the cell specific productivity was constant. Renewal of proteins was omitted because the protein content in the system persisted at a high level. Therefore, self-conditioning substances of the cells were retained in the system as well as the expensive medium components (proteins with catalytic or stimulating function). Seventy to 80% of medium costs and medium quantity were saved for each medium recycling step. Only cheap metabolites that are consumed by the cells had to be supplemented. Uptake rates of glucose and amino acids were calculated to establish a suitable supplementation mixture for the recirculated medium.

Animals↗
PubMed1991

Optimization of serum-free fermentation processes for antibody production.

Serum free fermentation procedures of cell cultures have got a wide application in production of biochemicals. But, cells cultured in serum free media in general are more sensitive to changes in culture condition, especially to nutrient limitation. There are no substances from serum which can support the cells when conditions are changing. In this study special attention is directed to amino acid utilization of mouse hybridoma in batch, chemostat and perfusion fermentations. Detailed data are presented which show the considerable difference of amino acid consumption rates in different fermentation modes. Already, in batch mode there are differences of the two investigated mouse hybridoma cell lines, although they are derived from the same myeloma line. In chemostat running at a dilution rate representing maximal growth rate most of the consumption rates are significant higher than in batch. On the other hand, in perfusion mode the rates are lower than in batch. This indicates clearly the different conditions of the fermentation modes. Therefore, it is necessary to develop serum free processes under the desired production conditions. An accurate analysis of the process is strongly recommended.

Amino Acids↗
PubMed1991

In vitro study on the impact of fish sera on the survival and fine structure of the eel-pathogenic acanthocephalan Paratenuisentis ambiguus.

The effects of fish sera on the growth and fine structure of infective larvae of the eel-pathogenic acanthocephalan Paratenuisentis ambiguus (Eoacanthocephala: Tenuisentidae) were studied under in vitro conditions using sera from the final host Anguilla anguilla and from two accidental fish hosts as well as fetal calf serum. As controls larvae were also kept in medium in the absence of serum and in experimentally infected eels. Sera from the accidental fish hosts carp and rainbow trout exerted toxic effects on the acanthocephalans. Worms maintained in medium containing sera from these two fish were contracted and displayed inverted probosces. Moreover, the tegument exhibited vacuolization and the formation of necrotic areas, including lysis of the mitochondria. Due to these effects, the parasites died at 21 (rainbow trout) or 21-50 days (carp) post-incubation. Eel sera had no toxic effect on the infective larvae. The growth of the larvae in medium depended on the composition of the latter, but was reduced as compared with that in the natural final host. Based on these results, we conclude that components of the hosts' blood sera play a role in the determination of the host specificity of P. ambiguus.

Acanthocephala↗
PubMed1991

Glutamate and glycine co-activate while polyamines merely modulate the NMDA receptor complex.

1. Agonists may act at any one of three sites on the N-methyl-D-aspartate (NMDA) receptor-effector complex to promote opening of the associated ion channel. The three sites are activated by i) NMDA, L-glutamate, aspartate, and other dicarboxylic amino acids; ii) glycine, D-serine, D-cycloserine, and others; iii) the polyamines spermine or spermidine, but not cadaverine or putrescine. 2. This opening by exogenous agonists is reflected by an enhanced binding of the phencyclidine-like dissociative anesthetic [3H]MK-801 to rat cortical membranes (well washed to remove endogenous agonists, e.g., L-glutamate, glycine). 3. The effects of adding combinations of agonists yielded stimulation approximately equal to the sum of each agonist's effect, suggesting that in the first approximation the three classes act at independent sites. 4. When the glutamate (E) site was antagonized with D-2-amino-5-phosphonopentanoate (D-AP5), no stimulation in binding could be elicited by agonists at the two other sites. Activation of the E site is therefore necessary but not sufficient for channel opening. 5. When the glycine (G) site was antagonized with 7-chlorokynurenate, no stimulation in binding could be elicited by agonists at the other two sites. Activation of the G site is therefore necessary but not sufficient for channel opening. 6. Of the two putative antagonists for the polyamine (PA) site, ifenprodil fails to completely inhibit the binding of [3H]MK-801, whereas arcaine inhibited [3H]MK-801 binding completely. We present data which question the selectivity of arcaine for the polyamine site, and propose that the polyamine site is merely modulatory, but neither necessary nor sufficient, for channel opening.

2-Amino-5-phosphonovalerate↗
PubMed1991

Antagonism between retinoic acid receptors.

In the developing mouse, retinoic acid receptors (RARs) beta and gamma 1 are expressed in characteristic spatiotemporal patterns which are correlated with different developmental fates of the respective tissues. Understanding the cues that regulate the expression of the various RARs may therefore provide insights into the process of tissue diversification. Transcription of RAR beta is rapidly upregulated through a retinoic acid-responsive element (here referred to as the beta RARE) in its promoter. Like RAR alpha and RAR beta, RAR gamma 1 has been implicated in the activation of the beta RARE. Therefore, it is puzzling that RAR beta and RAR gamma 1 appear to be expressed in reciprocal patterns. In the present report, we show that RAR gamma 1, one of the two predominant RAR gamma isoforms, can inhibit the activity of RAR gamma 2, RAR beta, and endogenous RAR on the beta RARE. In contrast, the three RAR gamma isoforms tested and RAR beta activated a palindromic thyroid hormone response element with similar levels of efficiency. The differential activity of RAR gamma 1 compared with that of RAR beta appears to reside in both the N-terminal and the C-terminal halves of RAR gamma 1. RAR gamma 1-mediated inhibition of other RARs may involve competition for the response element as well as direct interaction with other receptors and might be part of a regulatory system contributing to the characteristic tissue distribution of the various RARs.

Animals↗
PubMed1991

[Spongious glioneuronal dystrophy with diffuse fatty degeneration of the liver].

Reported in this paper are autopsy findings recorded from a boy who had died at the age of eight month. They included a spongy dystrophic tissue syndrome of the central nervous system associated with diffuse fatty degeneration of the liver. The case is considered to be in the category of glioneuronal dystrophy and is discussed under aspects of differential diagnosis.

Brain↗
PubMed1990

Photolabile, spacer-modified oligosaccharides for probing malto-oligosaccharide binding sites in proteins.

O-Deacylation and S-deacylation of the diastereomers of 2-azido-4-S-benzoyl-4-mercaptobutyl 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranoside (9) with methanolic sodium methoxide and coupling of the resulting thiol to methyl 3,4-anhydro-6-deoxy-beta-L-arabino-hex-5-enopyranoside (2) gave the corresponding diastereomers of the spacer-modified disaccharide methyl 4-S-(3-azido-4-alpha-D-glucopyranosyloxybutyl)-6-deoxy-4-thio-alph a-D-xylo-hex-5-enopyranoside (10). Glucosylation of the diastereomers of 10 with alpha-cyclo-dextrin-CGTase and treatment of the products with beta-amylase gave the diastereomers of the spacer-modified oligosaccharides methyl 4-S-(3-azido-4-alpha-maltosyloxybutyl)-6-deoxy-4-thio-alpha-D-xylo -hex-5-enopyranosides (11) and 4-S-(3-azido-4-alpha-maltotriosyloxybutyl)-6-deoxy-4-thio-alpha-D- hex-5-enopyranosides (12). The diastereomers of 10 each had a good affinity for pancreatic alpha-amylase and the maltose-binding protein from E. coli. The affinities of the diastereomers of 11 and 12 were higher by at least one order of magnitude.

ATP-Binding Cassette Transporters↗
PubMed1990

Metabolism and actions of 2-deoxy-2-fluoro-D-galactose in vivo.

The synthetic D-galactose analog 2-deoxy-2-fluoro-D-galactose (dGalF) offers unique advantages for studies of the D-galactose pathway by non-invasive techniques using 19F-NMR spectroscopy or positron emission from the 18F-labeled compound. The metabolism of 2-deoxy-2-fluoro-D-galactose was studied in rodents using the unlabeled, the 18F-labeled, and the 14C-labeled D-galactose analog. Analyses for the metabolites of 2-deoxy-2-fluoro-D-galactose were performed by HPLC, enzymatic methods, and 19F-NMR spectroscopy in vivo and in vitro. The metabolism of 2-deoxy-2-fluoro-D-galactose was most active in the liver which took up the major part of the administered dose of the 14C-labeled D-galactose analog, but renal excretion was also pronounced. This was confirmed by in vivo scanning of the rat using the 18F-labeled sugar (1.5 microCi/g; 25 nmol/g) and examination by positron-emission tomography and gamma camera. The dose dependence of the levels of the hepatic metabolites of 2-deoxy-2-fluoro-D-galactose was investigated for doses between 25 nmol/g body mass and 1 mumols/g body mass. After 1 h, the major part of the acid-soluble uracil nucleotides consisted of UDP-2-deoxy-2-fluoro-D-hexoses when the dose was at least 0.1 mumols/g. With higher doses, 2-deoxy-2-fluoro-D-galactose 1-phosphate became the predominant initial metabolite. After a dose of 1 mumols/g 2-deoxy-2-fluoro-D-galactose 1-phosphate accumulated rapidly (5.3 +/- 0.4 mumols/g liver after 30 min) followed by the formation of UDP-2-deoxy-2-fluoro-D-galactose and UDP-2-deoxy-2-fluoro-D-glucose (0.7 +/- 0.1 mumols/g and 1.8 +/- 0.1 mumols/g, respectively, after 5 h). The diversion of uridylate, due to the accumulation of UDP-2-deoxy-2-fluoro-D-hexoses, was associated with a rapid depletion of hepatic UTP, UDP-glucose, and UDP-galactose. The UTP content was decreased to 11 +/- 6% of normal within 15 min after administration of 2-deoxy-2-fluoro-D-galactose at a dose of 1 mumols/g. The UTP-depleting action was minimal, however, at a dose of 25 nmols/g or less, indicating that interference in uridylate metabolism would be negligible at the doses required for positron-emission tomography of the liver using the 18F-labeled compound. At higher doses, the UTP deficiency induced by 2-deoxy-2-fluoro-D-galactose could be useful in the chemotherapy of D-galactose-metabolizing tumors such as hepatocellular carcinoma.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[False aneurysm: a complication of carotid endarterectomy].

False aneurysm of the carotid artery is a rare complication of carotid endarterectomy. We present a 65-year-old woman and a 68-year-old man with this condition. In 1 the artery had been closed with a Dacron patch graft, and in the other by direct suture. In the first case the aneurysm was successfully repaired with an expanded GoreTex (PTFE) patch graft sutured with monofilament nylon. In neither case was an organism grown from cultures taken at operation. The incidence of false carotid aneurysm as a complication of endarterectomy is only 0.3%. Usually infection is the main cause. It is therefore surprising that closure with a synthetic patch-graft is not a predisposing factor in the development of false carotid aneurysms, neither according to the literature nor in our own very limited experience with this complication.

Aged↗