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Biomedical subjects

E Nilsson

Publications and source records attributed to E Nilsson.

At least 109 records · Page 6Linked to original sources

Characterization of the flavin reductase gene (fre) of Escherichia coli and construction of a plasmid for overproduction of the enzyme.

The enzyme NAD(P)H:flavin oxidoreductase (flavin reductase) catalyzes the reduction of soluble flavins by reduced pyridine nucleotides. In Escherichia coli it is part of a multienzyme system that reduces the Fe(III) center of ribonucleotide reductase to Fe(II) and thereby sets the stage for the generation by dioxygen of a free tyrosyl radical required for enzyme activity. Similar enzymes are known in other organisms and may more generally be involved in iron metabolism. We have now isolated the gene for the E. coli flavin reductase from a lambda gt11 library. After DNA sequencing we found an open reading frame coding for a polypeptide of 233 amino acids, with a molecular weight of 26,212 and with an N-terminal segment identical to that determined by direct Edman degradation. The coding sequence is preceded by a weak ribosome binding site centered 8 nucleotides from the start codon and by a promoterlike sequence centered at a distance of 83 nucleotides. In a Kohara library the gene hybridized to position 3680 on the physical map of E. coli. A bacterial strain that overproduced the enzyme approximately 100-fold was constructed. The translated amino acid sequence contained a potential pyridine nucleotide-binding site and showed 25% identity with the C-terminal part of one subunit (protein C) of methane monooxygenase from methanotropic bacteria that reduces the iron center of a second subunit (protein A) of the oxygenase by pyridine nucleotides.

Amino Acid Sequence↗

On the binding of tumor necrosis factor (TNF) to heparin and the release in vivo of the TNF-binding protein I by heparin.

Tumor necrosis factor (TNF), a protein released by activated macrophages, is a central mediator of the host response to infection and inflammation. The TNF-binding protein I (TNF-BP-I) is a soluble fragment of the p60 transmembrane TNF receptor and an antagonist to TNF. The level of serum TNF-BP-I was found to be increased in patients with renal insufficiency as a result of a decrease in the glomerular filtration rate. During hemodialysis of patients with renal failure there was a rapid but transient increase in serum TNF-BP-I. This increase was found to be caused by heparin given before dialysis and a similar dose-dependent response to heparin was observed also in healthy individuals. The finding of a repeated release of TNF-BP-I into the circulation with intermittent injections of heparin indicates that TNF-BP-I is present both in a storage pool and in a circulating pool. The mechanism for the heparin-mediated release of TNF-BP-I was not explained; TNF-BP did not show affinity for heparin. On the other hand, TNF was found to have affinity for heparin and it could also be dissociated from heparin by TNF-BP-I. It is suggested that heparin-like molecules of the extracellular matrix can retain TNF in physical proximity with target cells and restrict the actions of TNF and protect against systemic harmful manifestations.

Carrier Proteins↗

Urinary excretion of CGS 5,649 and its conjugated glucuronide and sulfate in man.

Experiments in animals have indicated that CGS 5,649 B [6-(2-isopropylaminopropyl)-3-pyridinol fumarate] might enhance memory and learning processes and might be a valuable drug for treatment of impairment of vigilance and mental performance in the elderly. CGS 5,649 (I) is extensively metabolized. Therefore, we investigated the excretion of the drug and its conjugates (I-SULF,I-GLUC) into urine after oral administration of 1200 mg of the fumarate salt of I to one healthy male volunteer. Three HPLC methods were developed to analyze the three compounds in urine: a. Solid-phase extraction and UV-measurement at 280 nm; b. Dansylation followed by fluorometric detection (lambda ex 340, lambda em 525 nm); c. Direct injection of diluted urine, gradient system with ion-pair reagent and UV-detection at 280 nm. The conjugates were measured after enzymatic hydrolysis with glucuronidase/sulfatase and sulfatase. I-GLUC was also measured directly since a synthetic sample had become available. Results from the different analytical methods showed agreement: about 100% of the administered dose was excreted within 24 h; the relative amounts of I, I-SULF and I-GLUC were about 1:2:2; after oral administration, CGS 5,649 B is rapidly and completely absorbed; it is eliminated from plasma by conjugation and direct excretion into urine.

Chromatography, High Pressure Liquid↗

Effect of the new selective COMT inhibitor CGP 28014 A on the formation of 3-O-methyldopa (3OMD) in plasma of healthy subjects.

CGP 28014 A is a specific inhibitor of catechol-O-methyl transferase (COMT). The effect on COMT was assessed with the levodopa test in 5 unmedicated subjects and after pretreatment with 200-600 mg CGP 28014 p.o. Plasma concentrations of DOPA, 3-O-methyldopa (3OMD), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid were measured. CGP 28014 A decreased 3OMD not dose-related by 67% (p less than 0.05). This, and an increase of DOPAC shows COMT inhibition by this compound in humans.

3,4-Dihydroxyphenylacetic Acid↗

Vecuronium dose-response and maintenance requirements in patients with myasthenia gravis.

Eleven myasthenia gravis and seven control patients were studied during N2O/O2-fentanyl anesthesia to determine the ED50, ED95, and maintenance requirement of vecuronium using both mechanomyography and electromyography. The ED95 of vecuronium was 17 (range 8-34) micrograms/kg in patients with myasthenia gravis, and this was significantly related to patient's acetylcholine receptor antibody titer (r = -0.75, P less than 0.01). The average ED95 value was 250% greater in control than in myasthenic patients (P less than 0.01). The hourly requirement of vecuronium to maintain an 80-90% neuromuscular blockade was 38 +/- 10 micrograms/kg in myasthenic and 120 +/- 27 micrograms/kg in control patients (P less than 0.001). When these requirements were related to individual ED95 doses, they were comparable indicating similar time durations of effect of vecuronium following an equipotent dose in myasthenic and in control patients.

Adult↗

Synovial cells responding to a 65-kDa mycobacterial heat shock protein have a high proportion of a TcR gamma delta subtype uncommon in peripheral blood.

We have analysed the ability of T cells from synovial fluid mononuclear cells (SFMC) and from peripheral blood mononuclear cells (PBMC) of inflammatory arthritic diseases to proliferate in response to mycobacterial antigens (65-kDa heat shock protein [hsp] of BCG, whole BCG) and to rat collagen type II. The SFMC demonstrated a significantly greater ability to respond to 65-kDa hsp of BCG, and to whole BCG, compared with PBMC from the same patients. With collagen type II, only a small proportion of the patients showed a proliferative response, although with this antigen also SFMC responded better than PBMC. There was no difference between SFMC and PBMC in the response to control antigen (tetanus toxoid), phytohaemagglutinin (PHA), or interleukin 2 (IL-2). A high proportion of cells in SFMC-derived short-term T-cell lines were of TcR gamma delta type, often exceeding the number of TcR gamma beta type. There was a significantly higher proportion of TcR gamma delta cells in the SFMC lines compared with the PBMC lines, and a large part of the TcR gamma delta cells in the SFMC cultures was CD8+. The SFMC lines had a high proportion of delta-TCS-1+ cells (V delta 1) among their TcR gamma delta cells, always exceeding the percentages of Ti gamma A+(V gamma 9) and BB3+ (V delta 2). In the PBMC lines, the distribution of TcR gamma delta subtypes was markedly different, with a Ti gamma A+/BB3+ population in the majority. These data argue for a different subpopulation distribution of TcR gamma delta cells in synovial fluid compared with peripheral blood of patients with inflammatory arthritic diseases.

Antigens, Bacterial↗

Neuromuscular effects of isoflurane in patients with myasthenia gravis.

Seventeen myasthenia gravis and seven control patients were studied mechano (MMG)- and electromyographically (EMG) during isoflurane/oxygen/air anaesthesia. In myasthenic patients the mean train-of-four ratio and neuromuscular block (by MMG) during 1.9 MAC isoflurane anaesthesia were 55 +/- 9% and 46 +/- 12%, respectively. The correlation between simultaneous MMG and EMG measurements was excellent (r2 = 0.933, P less than 0.001). The occurrence of HLA-B8 together with acetylcholine receptor antibodies seems to predispose myasthenic patients to a neuromuscular depression produced by isoflurane. Our current and prior results show that isoflurane possesses approximately twice as strong a neuromuscular blocking effect as halothane in myasthenic patients.

Adult↗

Rapid clearance of xanthines from airway and pulmonary tissues.

The airway and pulmonary fate of two antiasthma xanthines was examined in a guinea pig perfused lung preparation where the airway mechanics and airway microvascular perfusion are maintained at near normal values. 14C-theophylline or 14C-enprofylline was infused for 10, 30, and 300 s into the pulmonary artery of the guinea pig isolated lung. The radioactivity increased rapidly (within 10 s) in tracheobronchial as well as in lung tissue, confirming that the large airway microcirculation was well supplied also by the perfusion. The effluent concentrations of total 3H and 14C radioactivity at the onset, during, and after intrapulmonary infusion of 14C-labeled xanthines and 3H-sucrose were closely associated, suggesting that the xanthines, like sucrose, largely distributed in extracellular fluid and were not taken up by the tissues. No metabolites of enprofylline or theophylline could be detected in the lung tissue or lung effluent, suggesting that xanthines are not biotransformed by the guinea pig lung. After intratracheal instillation of 14C-theophylline, the peak radioactivity in the lung effluent appeared in the second 15-s fraction after instillation, and after 10 and 60 min, 68.1 +/- 4.7% and 86.9 +/- 8.4%, respectively, of the given dose had appeared in the lung effluent. The present data suggest a mainly extracellular distribution and a rapid clearance of xanthines from the lung and airway tissues. The rapid disappearance of topical theophylline may explain the lack of success of inhalation therapy with this drug.

Animals↗

Characterization in vitro of a human tumor necrosis factor-binding protein. A soluble form of a tumor necrosis factor receptor.

Tumor necrosis factor (TNF) is a pleiotropic mediator of inflammatory responses. A cysteine-rich, highly glycosylated 30-kD TNF-binding protein (TNF-BP) purified from urine may have a role in regulation because it protects in vitro against the biological effects of TNF. The cytotoxic effect of TNF on the fibrosarcoma cell line WEHI 164 was inhibited by 50% at a 10-fold excess of TNF-BP. The binding of TNF to the receptor was partially reversed after the addition of TNF-BP. Results from biosynthetic labeling of cells with 35S-cysteine followed by immunoprecipitation with anti-TNF-BP indicated that TNF-BP is formed and released at the cell surface by cleavage because no corresponding cellular polypeptide was observed. A cellular 60-kD polypeptide, which was immunoprecipitated with anti-TNF-BP, may correspond to the transmembrane TNF-receptor molecule and be the precursor of TNF-BP. Thus, TNF-BP appears to be a soluble form of a transmembrane TNF-receptor. Moreover our results demonstrate that the production of TNF-BP is increased when the TNF receptor is downregulated in cells by treatment with TNF or by activation of protein kinase C with phorbol esters. TNF-BP may be an important agent that blocks harmful effects of TNF, and, therefore, useful in clinical applications.

Cell Survival↗

The influence of musculo-skeletal load, and other factors, on staff turn-over in fishery: a post employment questionnaire study.

Five hundred and seventy five out of 1642 fishermen from the Swedish west coast left the trade during the period 1982-1987 for reasons other than age retirement or death. A questionnaire study directed to all these fishermen showed that the majority of the fishermen leaving the trade were young and most of them left fishing within the first few years. The major reasons for leaving the job were low or uncertain earnings, long absence from home or musculo-skeletal symptoms. The major advantages with the work given by the ex-fishermen were working outdoors, good fellowship, personal influence on and excitement of the work. The frequency of subjective musculo-skeletal symptoms was lower among the ex-fishermen than among active fishermen in a previous investigation. However, the active fishermen had to a lower extent been unable to perform daily work due to their symptoms. Seasickness had been a problem for a portion of the ex-fishermen.

Adult↗

Metabolism of N-acetyl-L-cysteine. Some structural requirements for the deacetylation and consequences for the oral bioavailability.

Rat liver, lung and intestine homogenates deacetylated N-acetyl-L-cysteine. Nearly stoichiometric amounts of L-cysteine were recovered. In rat liver, the enzyme activity was associated with the cytosolic fraction. Liver cytosol was much less active. N-Acetyl-D-cysteine or the disulphide of N-acetyl-L-cysteine were not deacetylated or in other ways consumed in vitro. Isolated, perfused rat liver did not retain or metabolize N-acetyl-L-cysteine to any measurable extent during single-pass experiments. N-Acetyl-L-cysteine or N-acetyl-D-cysteine were injected into a ligated segment of rat intestine in situ. After 1 hr 2% of the L-isomer and 35% of the D-isomer remained in the intestinal lumen. Systemic plasma levels were less than 3 microM of the L-form and congruent to 40 microM of the D-form. We conclude that deacetylation in the intestinal mucosa and possibly in the intestinal lumen is the major factor determining the low oral bioavailability of N-acetyl-L-cysteine. The deacetylation is discussed on the basis of the subcellular localization and the structural requirement of the reaction.

Acetylation↗

Pulmonary disposition of the potent glucocorticoid budesonide, evaluated in an isolated perfused rat lung model.

Budesonide is a potent glucocorticoid developed for the local treatment of respiratory disorders such as bronchial asthma and allergic rhinitis. We now report the lung disposition of 3H-budesonide administered either via the air passages or via the pulmonary circulation using isolated perfused and ventilated rat lungs. A rapid initial absorption was found after intratracheal administration of a clinically relevant dose of the drug. However, about half of the given dose was slowly released into the lung perfusate. The lung uptake of budesonide from the pulmonary circulation was relatively high (lung extraction ratio about 0.12). These data points to a high lung affinity for budesonide. The drug was not biotransformed in the lung. The high lung affinity and absence of lung metabolism can be important factors to explain the good therapeutic effects seen with budesonide in the clinic.

Animals↗

Major amputation in a defined population: incidence, mortality and results of treatment.

Medical records of all patients, from a defined population of 88,000 inhabitants, who underwent major lower limb amputation during 1980-82 were retrospectively scrutinized. The records showed 131 amputations were performed in 106 patients at the district hospital and 22 amputations on 17 patients at the local university hospital, referral centre, altogether 57 men and 66 women. This gave an amputation incidence of 46 per 10(5) inhabitants per year. Of the amputees 47 per cent were older than 80 years. Only two patients underwent reconstructive vascular surgery (at the university hospital) before surgery. Final amputation level was above-knee in 61 per cent of the patients treated at the district hospital. Mortality rates at 30 days and 2 years after the amputation were 23 and 56 per cent, respectively, and the age-corrected survival after 2 years was 55 per cent. For patients who came from and eventually returned to their own homes the mean hospital stay amounted to 184 days (postoperative deaths excluded). After amputation 26 patients were trained to wear a prosthesis and 16 of these used the prosthesis 2 years after amputation. The present study underlines the need for prospective and parallel studies of vascular surgery and amputation as well as analyses of the risk factors involved in lower limb ischaemia in defined populations.

Adult↗

Recombinant lymphotoxin enhances the growth of normal, but not of chronic myeloid leukemic, human hematopoietic progenitor cells in vitro.

The effects of recombinant lymphotoxin (rLT) and tumor necrosis factor (rTNF) on the growth of clonogenic normal and leukemic hematopoietic cells were investigated. Two opposite and dose-dependent effects of rLT on normal CFU-GM were found. Low concentrations (5pM) did stimulate the growth, while higher amounts of rLT showed an antiproliferative effect. In contrast, the effect of rTNF was only an inhibition of growth in a dose-dependent fashion. In chronic myeloid leukemia (CML), the CFU-GM was resistant to the growth stimulatory effect of rLT. Furthermore, CML-cells were found to be more susceptible than normal CFU-GM to the antiproliferative effect of both rLT and rTNF. These results show that LT and TNF exhibit qualitative differences in the effects on hematopoietic cells and that CML-cells display an increased susceptibility for the cytostatic effects on LT and TNF.

Bone Marrow Cells↗