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Biomedical subjects

E Roth

Publications and source records attributed to E Roth.

At least 145 records · Page 8Linked to original sources
PubMed1989

Phenylalanine and tyrosine metabolism in renal failure: dipeptides as tyrosine source.

Several lines of evidence suggest that tyrosine formation is impaired in renal failure. The concentration of tyrosine is decreased and the phenylalanine/tyrosine ratio is increased in plasma and in skeletal muscle cells. After an oral or intravenous load, the rise of plasma phenylalanine is augmented, the clearance is decreased, oxidation is diminished and the corresponding rise of plasma tyrosine level is blunted. Tyrosine elimination and oxidation are not altered in uremia. The defect in tyrosine formation may be especially important in uremic patients on a low protein diet supplemented with tyrosine-free essential amino acid preparations and in subjects on artificial nutritional support. Thus, tyrosine should be regarded as a conditionally essential amino acid in renal failure and should be supplied exogenously, at least in these patient groups. Oral tyrosine supplementation was shown to replete plasma and intracellular pools and improve nitrogen balance in chronic renal failure patients on a low protein diet. However, because of poor solubility in aqueous solutions, tyrosine cannot be included in the free form in amino acid solutions for parenteral nutrition. To circumvent stability or solubility problems, tyrosine containing dipeptides and/or N-acetyl-tyrosine may serve as tyrosine sources for parenteral supply. Renal failure does not affect alanyl-tyrosine hydrolysis, and there is an immediate increase of plasma tyrosine concentration after peptide infusion. Elimination and hydrolysis of glycine-tyrosine is retarded in renal failure, but the clearance exceeds clinically relevant infusion rates. After infusion of N-acetyl-tyrosine, no increase in plasma tyrosine is seen, and the half-life N-acetyl-tyrosine is grossly prolonged in uremia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Selective effect of personality markers and psychosocial stress on T lymphocyte subpopulations].

Measurements were made of cellular immune system parameters in a group of healthy medical students. On the basis of psychosocial stress encountered during a five-day topic-centered self-awareness course, we investigated modulation in immunity in relation to personality characteristics. 6 days before the beginning of the seminar personality profiles were drawn and blood samples taken. Further immunological measurements were made on day four of the seminar and three weeks after its conclusion. On the fourth day of the seminar we observed throughout the group higher lymphocyte and suppressor/cytotoxic T lymphocyte counts in comparison with counts one week earlier, and likewise a heightened responsiveness to PHA- and IL-2 stimulation. The T lymphocyte counts had dropped. In subjects with a higher need for succorance/nurturance, the depression of the immune system was manifested in a drop in the helper/inducer T lymphocyte counts, and in the more achievement- and order-oriented subjects in a downregulation as observed by higher suppressor/cytotoxic T lymphocyte counts. Our results show that under psychosocial stress, healthy people experience on the one hand an activation of the immune system, and on the other hand an immunodepression bearing a specific relation to personality characteristics.

Adult↗
PubMed1988

Natural killer cell activities of patients with breast cancer against different target cells.

Natural killer (NK) cell activity against K 562 erythroleukemic- and MCF-7 breast carcinoma-derived cells was monitored in short-term (3 h/K 562) and long-term (18 h/MCF-7) chromium release tests for 60 patients with untreated primary breast disease. Target cell lysis was the same for patient groups with benign (n = 13) and malignant (n = 47) breast disease (27% versus 36% mean chromium release; target:effector ratio 40:1 for K 562 and 28% versus 40% for MCF-7 cells). NK activity as defined by short-term lysis of K 562 cells did not correlate with MCF-7 cell lysis in long-term assays for the carcinoma patients. This functional heterogeneity of natural cytotoxic activities of breast cancer patients was confirmed by a different age distribution for K 562 and MCF-7 cell lysis and high levels of MCF-7-directed NK activity in the grade I tumor group (56.2%). Our results indicate that measurement of peripheral blood NK activity against a breast carcinoma-derived cell line (MCF-7) defines a disease-related natural cytotoxic activity which correlates better with prognostic tumor parameters (tumor grading) than NK activity as defined by the lysis of K 562 erythroleukemic cells. NK activity testing against breast carcinoma cell lines should be used to monitor natural cytotoxic activities in breast cancer patients and its modulation by different routes of treatment.

Adult↗
PubMed1988

Influence of two glutamine-containing dipeptides on growth of mammalian cells.

The instability of the amino acid glutamine prompted us to investigate substitute compounds appropriate for culture conditions. The effect of two glutamine-containing dipeptides, alanylglutamine (Ala-Gln) and glycylglutamine (Gly-Gln), on the growth behavior of a hematopoietic cell line in culture (K562) was investigated. Growth rates and [3H]thymidine incorporation rates of cells cultivated in sterile-filtrated media, containing glutamine (Gln) or Ala-Gln or Gly-Gln, were not statistically different. Although heart-sterilization of media containing Gln caused approximately 95% decomposition of the Gln, both dipeptides remained unaltered. Consequently, cell growth was drastically decreased when autoclaved free Gln-containing media were used, but growth was unaffected in the presence of autoclaved dipeptides. Both Ala-Gln and Gly-Gln have an advantage over free Gln as growth factors for cell culture due to the stability of the dipeptides during both autoclaving and storage; the biological activity, however, is comparable.

Cell Division↗
PubMed1988

Impaired cell-mediated immunity in the first week after burn injury: investigation of spontaneous blastogenic transformation, PHA, IL-2 response and plasma suppressive activity.

This study investigated alterations of cell-mediated immunity induced by trauma, operative treatment and infections in a group of 19 burned patients with a mean burn size of 42 +/- 22 per cent of the body surface area. We tested peripheral mononuclear blood cells (PMBC) for spontaneous blastogenic transformation (SBT), phytohaemagglutinin (PHA) and interleukin-2 (IL-2) responsiveness. Plasma samples were also assayed for inhibition of mitogen stimulation of control PMBCs. Mean values were calculated for the acute postburn period (days 0-3) and the following 4 days, before the development of septic complications. SBT was significantly increased in all patients during the second period of investigation (days 4-7) in comparison to normal controls and during the acute phase. The response to mitogen stimulation (PHA) was significantly suppressed during days 0-7 and the plasma samples showed high suppressive activities following PHA stimulation of control lymphocytes during the course of the study. No significant differences in rates of SBT, PHA responsiveness and plasma suppressive activity were found between those patients who developed bacteraemia and those with negative blood cultures. The latter group showed higher reactivity to added IL-2 in comparison to normal controls. Surgical treatment immediately after trauma (fasciotomy; day 0 or 1) resulted in further increased immunosuppression (PHA and IL-2 response), whereas after necrectomy (days 4-7) the immunological parameters showed no significant differences. It can be concluded that neither rates of SBT nor response to PHA can be used to identify patients at high risk for infection during the first week postburn.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Mass spectroscopic analysis of excimer laser ablated material from human corneal tissue.

The clinical feasibility of photorefractive keratectomy depends on the surface structure of the ablated cornea. Two factors that influence the remodeled surface are the homogeneity of the energy distribution and the properties of the laser source (energy and wavelength). Currently, the homogeneity of the beam is difficult to control. The second factor, laser source properties, was the focus of this study. We investigated the effect of laser wavelength and energy by analyzing the reaction products of photoablation. We monitored the fragments produced by UV-laser ablation of human corneas using mass spectroscopy in the range of 0 to 100 atomic mass units. At 248 nm (KrF), average photon energy was 5 mJ/cm2, increased to 90 mJ/cm2 by intervals of 5 mJ/cm2. At 193 nm (ArF), photon energy was increased by the same interval from 5 mJ/cm2 to 80 mJ/cm2. Our experiments showed that there was a fluence threshold of approximately 40 mJ/cm2 at 193 nm (ArF) and 50 mJ/cm2 at 248 nm (KrF). Exceeding this threshold led to sudden increases in the number and relative intensity of fragment peaks in mass spectroscopy. This indicates the onset of multiple-photon processes and effective photochemical breakdown. There was a significant difference between both wavelengths in the distribution of mass peaks, indicating higher ionization power at 193 nm.

Adult↗
PubMed1988

Alanylglutamine reduces muscle loss of alanine and glutamine in post-operative anaesthetized dogs.

1. The present study examined the effect of an infusion of the dipeptide alanylglutamine or of the corresponding amino acids alanine and glutamine in equimolar amounts (10 mumol min-1 kg-1) on the canine hindlimb exchange of alanine and glutamine in the post-operative anaesthetized dog. In contrast to glutamine, the dipeptide alanylglutamine is stable in aqueous solution and therefore would be a suitable substrate for parenteral nutrition. 2. The infusion of alanylglutamine increased (a) the arterial concentration of alanylglutamine to a plateau level (120 +/- 9.5 mumol/l, mean +/- SEM) 20 min after start of the infusion, (b) the mean arterial alanine concentration from 761 +/- 42 to a plateau of 1500-1700 mumol/l (P greater than 0.01) and (c) the arterial glutamine concentration from 407 +/- 51 to a plateau of 1050-1500 mumol/l (P greater than 0.01). Alanine and glutamine levels were slightly higher (14% and 26%, respectively, NS) in the group receiving the equimolar amount of alanine and glutamine. 3. Infusion of alanylglutamine for 1 h abolished the net efflux of glutamine (from -0.80 +/- 0.1 to -0.03 +/- 0.2 mumol min-1 kg-1; P greater than 0.05) and invoked a net influx of alanine (from -0.50 +/- 0.19 to +0.27 +/- 0.14 mumol min-1 kg-1; P greater than 0.01). These changes were similar to those achieved when the two amino acids were infused. 4. This study demonstrates that during short-term administration of alanylglutamine or of the corresponding amino acids the nitrogen release from the hindlimb of the anaesthetized post-operative dog via alanine and glutamine is reduced.

Alanine↗
PubMed1988

Rehabilitation outcomes in complete C5 quadriplegia.

Establishment of rehabilitation goals for spinal cord injury patients generally has been based on the degree of residual motor function. Despite extensive clinical experience with spinal cord injury rehabilitation, there have been no reports of the ability of C5 quadriplegic patients to perform self-care and mobility skills before and after rehabilitation. This study was designed to examine the rehabilitation outcomes of 63 patients with C5 complete quadriplegia, who completed an interdisciplinary inpatient rehabilitation program, using the 100-point modified Barthel Index as a means of rating functional status. There were statistically significant increases in the mean modified Barthel index scores from 7.1 on admission to 28.9 on discharge for the entire group of patients. The self-care subscore increased significantly from 6.5 on admission to 20.0 on discharge and the mobility subscore increased significantly from 0.5 on admission to 8.9 on discharge. Ability to perform self-care and mobility subscore tasks is described. This study documented significant improvements in function during comprehensive rehabilitation among patients with C5 spinal cord injury.

Activities of Daily Living↗
PubMed1988

The adaptation of Plasmodium falciparum to oxidative stress in G6PD deficient human erythrocytes.

It has recently been found that growth of P. falciparum in human G6PD deficient red cells is impaired in vitro; however, the inhibition is overcome after two or three growth cycles. There is evidence to suggest that the parasite can produce its own G6PD enzyme which may compensate for the lack of host enzyme and could account for the resumption of normal growth in G6PD deficient host cells. It is unclear whether the parasite enzyme can enable the host cell to resist oxidative stress as normal cells do. To answer this question, P. falciparum was grown in vitro in: (a) normal red cells, (b) G6PD deficient red cells for one growth cycle only, (c) G6PD deficient cells for a minimum of five cycles. All groups were then challenged with acetylphenylhydrazine (APH) which served as an oxidative stress. Both G6PD (A-) and Mediterranean deficient types were studied. The results show a two-fold increase in resistance to oxidative stress by parasites adapted to G6PD-Mediterranean deficient host cells as compared to unadapted ones, but the parasite-red cell system remains 4 times more sensitive to APH than normal infected cells. In parasitized G6PD (A-) red cells, evidence of adaptation could be seen in the growth curves, but no detectable increase in resistance to APH was found in adapted parasites. It is concluded that the role of the parasite G6PD is not likely to be mainly related to oxidative stress resistance and therefore other functions of this enzyme should be investigated.

Adaptation, Biological↗
PubMed1988

Asparaginase-induced derangements of glutamine metabolism: the pathogenetic basis for some drug-related side-effects.

Several side-effects of asparaginase therapy have been said to be a consequence of the glutaminase activity of Escherichia coli asparaginase, especially the deleterious influence on the liver function. We report here the drug-induced impairments of asparagine and glutamine metabolism in correlation to concentrations changes of plasma proteins, synthesized in the liver, in patients with acute lymphatic leukaemia. One hour after asparaginase application, plasma glutamine decreased to 5% (0-39%: median, range) of the initial values, with a subsequent rise to concentrations slightly lower than those prior to therapy. During the 14 days of drug application the fasting plasma concentrations of glutamine fell to a median of 63% of the pre-therapeutic levels, indicating a depletion of the glutamine pools. Two days after the end of asparaginase application, in one patient the glutamine concentrations increased to the pre-therapeutic range. Plasma concentrations of fibrinogen and antithrombin III decreased to 46% and 56%, respectively, of the initial values, with a slight increase 2 days after the end of therapy. The changes of plasma protein concentrations followed the course of plasma glutamine and asparagine. From that we deduce that the hepatic synthesis of the plasma proteins might be influenced by asparagine and glutamine depletion as a consequence of the therapy with E. coli asparaginase.

Amino Acids↗
PubMed1988

The use of enzymopathic human red cells in the study of malarial parasite glucose metabolism.

The in vitro growth of Plasmodium falciparum malaria parasites was assayed in mutant red cells deficient in either diphosphoglycerate mutase (DPGM) or phosphoglycerate kinase (PGK). In addition, cDNA probes developed for human DNA sequences coding for these enzymes were used to examine the parasite genome by means of restriction endonuclease digestion and Southern blot analysis of parasite DNA. In both types of enzymopathic red cells, parasite growth was normal. In infected DPGM deficient red cells, no DPGM activity could be detected, and in normal red cells, DPGM activity declined slightly in a manner suggestive of parasite catabolism of host protein. However, in infected PGK deficient red cells, there was a 100-fold increase in PGK activity, and in normal red cells, a threefold increase in PGK activity was observed. Parasite PGK could be recovered from isolated parasites, and a marked increase in heat instability of parasite PGK as compared with the host cell enzyme was noted. Neither cDNA probe was found to cross-react with DNA sequences in the parasite genome. It is concluded that the parasite has no requirement for DPGM, and probably has no gene for this enzyme. On the other hand, the parasite does require PGK, (an adenosine triphosphate [ATP] generating enzyme) and synthesizes its own enzyme, which must have been encoded in the parasite genome. The parasite PGK gene most likely lacks sufficient homology to be detected by a human cDNA probe. Enzymopathic red cells are useful tools for elucidating the glycolytic enzymology of parasites and their co-evolution with their human hosts.

Animals↗
PubMed1988

Plasma amino acid pattern of patients with HIV infection.

We measured the free amino acids in plasma of 58 patients with HIV infection and in six persons in the risk group. The HIV+ patients had significantly increased concentrations of arginine, phenylalanine, and glutamate in comparison with both age- and sex-matched controls and the members of the risk group. Glutamate concentrations increased only in an advanced stage of the disease (WR 5 and 6 of the Walter Reed staging classification), whereas arginine and phenylalanine increased independently of the stage. There was no correlation between the amino acid concentrations and the number of T4 and T8 lymphocytes, the sedimentation rate, and the existence or absence of Kaposi's sarcoma. The amino acid pattern of HIV-infected persons is similar to that of cancer patients or those with other immune deficiencies.

Acquired Immunodeficiency Syndrome↗