Insulin binding and receptor tyrosine kinase activity in skeletal muscle of carnivorous and omnivorous fish

We characterized the insulin receptors in skeletal muscle from several fish species with different nutritional preferences: brown trout (Salmo trutta fario), gilthead sea bream (Sparus aurata), tilapia (Tilapia mossambica), and carp (Cyprinus carpio), semipurified by affinity chromatography (wheat germ agglutinin-agarose). Total specific binding and number of receptors per unit weight of piscine white skeletal muscle were lower than those values found in mammalian skeletal muscle. The same parameters in carp muscle receptor preparations were severalfold higher than in trout muscle (binding capacity 440 +/- 47 fmol/mg glycoprotein in carp and 82 +/- 23 fmol/mg glycoprotein in trout). Piscine insulin receptors phosphorylated exogenous substrate poly(Glu,Tyr) but less so than mammalian receptors. Tyrosine kinase activity of receptors, calculated as percent of 32P incorporated into substrate in the presence of insulin compared with basal incorporation, was also highest in carp (210 +/- 4%) and lowest in trout (150 +/- 2%). In both trout and carp deprived of food for 15 days, specific binding of insulin decreased. Nevertheless, differences between the two species were retained. Our results demonstrate that particular properties of insulin receptors in fish skeletal muscle may be related to nutritional preferences. This finding coincides with the phenomenon of differential glucose tolerance in fish: carnivorous fish, such as trout, are less tolerant, whereas omnivorous fish, such as carp, readily utilize a carbohydrate-rich diet.

Increasing the efficiency of protein export in Escherichia coli

Export of recombinant proteins to the periplasm of Escherichia coli is in many cases preferable to cytoplasmic production. However, when the protein is overexpressed, export efficiency decreases significantly and some advantages of the system are lost. This is what happens when attempting to produce recombinant human interleukin-6 (hIL-6) as a pre(OmpA) fusion in E. coli. Assuming that the host protein export machinery becomes overloaded, we have tested the effect of providing the host with additional copies of two key components of that machinery. Supplementation with a plasmid bearing prlA4 (secY allele) and secE genes increased the ratio of mature to precursor hIL-6 from 1.2 to 10.8. The increase in processing ratio was associated with the accumulation of a larger amount of total (mature plus precursor forms) hIL-6. Providing a plasmid-borne wild-type prlA was ineffective compared to prlA4 allele. This suggests that the PrlA protein, a component of the translocator, recognizes features at the mature portion of secretory substrates independently of those at the signal peptide portion.

[Comparison of the diagnostic usefulness of immunoglobulins A and M in acute toxoplasmosis]

We compared the levels of IgA and IgM antibodies in nonimmunosuppressed patients with active toxoplasmosis to evaluate their diagnostic value. In group I (nine patients with toxoplasmosis) we determined the presence of anti-toxoplasma antibodies at the onset of the disease; in four of them we also studied the levels three months later. In group II (control) we tested 50 serum samples from healthy subjects. In both groups we investigated the presence of IgG with indirect enzyme immunoassay (EIA) (Eti-Toxok G, Sorin Biomedica); capture EIA was used to study IgA (Platelia Toxo IgA, Pasteur), and this method (Eti-toxok M, Sorin Biomédica) and the capture agglutination technique were used to study IgM (Toxo-ISAGA, Biomerieux). The nine patients in group I were positive for IgM (Sorin test) but one was negative with the capture agglutination technique and for IGA. All nine were positive for IgG, and IgG titers were increased in the patients studied a second time. In group II, none of the subjects had IgM; the levels of IgG were > 15 IU/mL in 18 subjects, and < or = 15 IU/mL but not absent, in the 32 remaining subjects. IgA was detected in eight of the 18 individuals with IgG levels > 15 IU/mL and in 11 of the 32 with levels < or = 15 IU/mL. The sensitivity of IgA was 88.8% and its specificity 62%; positive and negative predictive values were 29.6% and 96.8%, respectively. The assay of IgA in the course of active toxoplasmosis does not appear to be a more useful marker than IgM detection; however, the study population should be enlarged to include patients with reactivations of toxoplasmosis, before we can be more conclusive.

[Clinical effectiveness of naloxone in acute ethanol intoxication]

The first articles trying to link the effects of ethyl alcohol with those of opiates appeared in 1970. The first case of reversion from ethylic coma due to naloxone was described in 1978. Since then, many authors have reported different results related to the effectiveness of opiate antagonists in this clinical situation, without any of the studies showing a beneficial effect from its use. The purpose of the present study is to perform a double-blinded clinical trial with placebo to evaluate naloxone's clinical effectiveness in severe ethylic intoxication, using the Glasgow test (GT) to measure the level of consciousness. Treatment was randomly assigned to 38 patients of whom 18 received 2 mg of naloxone and 20 a placebo. Among the results, it was found that the best approximation of the level of alcoholemia responsible for ethylic coma, without the involvement of other toxic psychotropes, was made using the Glasgow test, especially in patients who are occasional drinkers. It was shown that naloxone indeed lacks effectiveness in ethylic coma, raising the level of consciousness only one or two points in the Glasgow test for the 15 to 45 minutes after its administration and primarily in the group of patients with the lowest levels of consciousness.

Circulating Candida antigens and antibodies: useful markers of candidemia

To investigate the utility of the 48-kDa antigen from Candida albicans in its commercial form (Directigen; Becton Dickinson) and three other serodiagnostic methods (detection of one antigen by Pastorex Candida [Sanofi Diagnostics Pasteur] and detection of immunoglobulin G [IgG] and IgM antibodies to C. albicans blastoconidia [bioMerieux]) for diagnosis of invasive Candida infection, we conducted a prospective clinical trial among 10 patients with candidemia (group 1), 30 patients colonized by C. albicans (group 2), 20 patients with bacteremia (group 3), and 20 subjects without clinical or microbiological evidence of infection. The Directigen system was positive for at least one serum sample each from eight patients in group 1. In groups 2, 3, and 4, it was positive for only three patients. There was no reaction to the Pastorex system in any of the patients infected with or colonized by C. albicans or in the non-Candida-carrying controls. The IgG antibody concentration oscillated between 100 and 800 (mean, 510 +/- 268) IU/ml for the patients in group 1. In this group, eight patients had IgG antibody levels of > 400 IU/ml. The percentages of persons with IgG antibody levels of > 400 IU/ml in groups 2, 3, and 4 were 43.3, 0, and 0, respectively. Specific IgM antibody was present in all group 1 patients but not in those in groups 2, 3, and 4. The sensitivity and specificity of the Directigen test were 65 and 97.1%, respectively. For the Pastorex test, the sensitivity was 0%. The sensitivity of IgG antibodies was 80%, with a specificity of 81.4%, while the IgM antibodies were 100% specific and sensitive. Both the positive and negative predictive values of specific IgM antibodies appeared to be superior to those of the other three tests.

Insulin and IGF-I receptors and tyrosine kinase activity in carp ovaries: changes with reproductive cycle

Insulin and insulin-like growth factor I (IGF-I) receptors from carp ovaries were semipurified with wheat germ agglutinin at different moments of the reproductive cycle and their binding characteristics and tyrosine kinase activity were studied. Specific receptors for insulin and IGF-I were found. IGF-I receptors presented higher binding (23.8 ± 1.5%), number of receptors (965 ± 20fm/mg) and affinity (KD 0.24 ± 0.03nM) than those shown for insulin receptors (4.1 ± 1%, 530 ± 85fm/mg and 0.85 ± 0.1nM, respectively). Insulin and IGF-I receptors have a tyrosine kinase activity which is not different from that found in muscle of the same species. Seasonal changes were found in binding, with maximum values for insulin and IGF-I reached at the end of pre-spawning period (June). However, while IGF-I binding was observed in all stages, insulin binding decreased in autumn and disappeared in winter, which suggests a different role for the two peptides in ovarian physiology.

Insulin binding to isolated hepatocytes of Atlantic salmon and rainbow trout

The questions addressed in this study were: 1) whether insulin added to the incubation medium can down-regulate (125)I insulin binding to isolated hepatocytes of Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss); 2) whether quantitative assessment of insulin processing can be made on isolated fish liver cells; 3) how ambient temperatures can affect insulin binding, and down-regulation of insulin receptors.After isolation and a short (up to 4h) "metabolic recovery period", liver cells were used either directly in (125)I insulin binding assay or first preincubated for 18h at 4°C or for 3h at 15°C, with or without mammalian or salmon insulin in concentrations ranging from 1 to 1000 nM.Preincubation at 15°C, decreased binding capacity (number of binding sites per liver cell) in all five independent hepatocyte preparations treated with 1000 nM insulin and in four out of five preparations treated with 100 nM insulin. At 4°C insulin binding sites were down-regulated in less than 50% of all hepatocyte preparations and only in the presence of 1000 nM insulin.Differential quantitive assessment was made of a) intact free insulin; b) insulin degraded; c) intact insulin bound to the cell membrane; d) internalized but degraded insulin, and e) intact insulin internalized by liver cells. Hepatocytes preincubated with 100 - 1000 nM insulin at 15°C bound and internalized less (125)I insulin.We hypothesize that in vivo, at water temperatures of 15°C and higher, extreme physiological levels of plasma insulin may regulate the numbers of insulin receptors in the salmonid liver. In contrast, in fish inhabiting cold waters the regulation of insulin receptors by circulating plasma insulin seems to be of little physiological importance.

[Prevalence of anti-Leishmania antibodies in parenteral drug addicts. Yield value of 2 study techniques]

BACKGROUND

The prevalence of antibodies anti-Leishmania in intravenous drug addict (IVDA) patients suspect of visceral leishmaniasis (VL) and the diagnostic profitability of two tests for detecting anti-Leishmania antibodies were studied.

METHODS

Serum samples corresponding to 91 healthy non IVDA individuals (group 1), 143 IVDA individuals attended in consultation for febrile illness and lymph node enlargement (group 2) with only one serum determination, and 42 IVDA individuals in whom sequential serologic study (group 3) was performed were analyzed. IgG and IgM antibodies were studied by indirect immunofluorescence (IIF). The individuals of group 1 and 90 of those of group 2 (45 with anti-Leishmania IgG antibodies and 45 without by IIF) were simultaneously studied by ELISA to analyze IgG antibodies.

RESULTS

No antibodies were detected in subjects from group 1 with the two techniques used. In group 2 IgG were detected in 43.3% of the patients (titer distribution: 46.8% at 1/32, 32.3% at 1/64 and > 1/64 in 21%). In group 3 seroconversion of IgG was found in 18 cases. In 6 patients IgM was observed: 3 from group 2 (with low titers of IgG) and the remaining pertained to group 3 being accompanied by seroconversion of specific IgG. In the remaining 15 patients of group 3 seroconversion of IgG did not accompany positive IgM. No association was found in the results obtained by IIF and ELISA (p = 0.3; chi 2).

CONCLUSIONS

It was found that indirect immunofluorescence and ELISA techniques are complementary methods in the indirect diagnosis of visceral leishmaniasis overall in the population of intravenous drug addicts. In this population acute disease may be manifested by IgG seroconversion with or without positive IgM although IgG seroconversion seems to be a more useful criteria given the greater number of patients in whom it is presented in this form. The high frequency of antileishmania antibodies in intravenous drug addict patients in Spain is of note.

[The pattern of the sensitivity of Aeromonas spp. that produce extraintestinal infections]

We studied the sensibility to several antimicrobics of aeromonas strains isolated in extraintestinal infections during a period of five years, in order to establish which could be the best empirical therapy in these processes. Twenty-two strains of A. hydrophila were evaluated, was isolated (8 from hemocultures, 6 from wound exudate, 2 from abscess aspirate, 2 from peritoneal fluid and 1 from urine, pleural fluid, bile and catheter). The identification was made using the GNI card System (Vitek System) and other tests. The sensibility was assessed using the GNS-BH and GNS-BI card System (Vitek), which allows to know the clinical category and CMI value in microgram/ml. All the strains presented some resistance to antibiotics. 77.8% of the strains were resistant to more than one antibiotic and 64.9%, to more than two antibiotics. We detected 21.7% strains resistant to 4 drugs. The most frequent resistance association was ampicillin, cephoxitine, cephazoline, cephalotine, with or without amoxicillin and clavulanic acid. All the strains were sensible to cephamandol, cephuroxime, cephtriaxone, cephtazidime, cephotaxime, thicarciline, aztreonam, azlociline, mezlociline, piperaciline, gentamycin, amikacine, chloranphenicol and ciprofloxacine. All the strains were resistant to ampicillin; 60.9% of the strains were sensible to the association amoxicillin and clavulonic acid. In conclusion, the treatment of extraintestinal infections does not differs basically from the treatment of the infections caused by Gram-negative bacillus. There are a broad range of effective antibiotics: aminoglycosides (gentamycin, tobramycin, amikacine), piperacyline, cephalosporines (cephuroxime, cephotaxime, cephtazidime and cephtriaxone), chloranphenicol, penemas, monobactanes of fluorquinolone.

[The contribution of "La España Médica" (1856-1866) to the introduction of anesthesiology in Spain]

The aim of this study was to analyse the contribution of "La España Médica " (1856-1866) to the introduction of anesthesiology in Spain. Thirty-seven articles on anesthesiology were published, with 19 articles (51.35%) being originals from spanish authors and 18 (48.64%) from abroad. By means of this medical newspaper from Madrid, Spanish physicians received information concerning the latest changes in anesthesiology with special emphasis on the introduction of amylene.

[Clinical and diagnostic characteristics of Aeromonas strains]

We studied the taxonomic, clinic, microbiological diagnostic and therapeutic characteristics of Aeromonas strains. Eleven geno-species have been isolated in human. They can be enterotoxigenic or enteroinvasive. These bacteria can be easily confused with other Gram negative bacilli (the Aeromonas are oxidase positive). They produce diarrhea but can only colonizer. In others localizations they are always diagnostic. Their detection in stools can be realized with the blood agar plus ampicillin or cefsulodin-novobiocin-irgasan agar. The treatment of extraintestinal infection is similar to the Gram negative infections. The Aeromonas are resistant to erythromycin, streptomycin and first generation cephalosporin. The beta-lactamic antimicrobials aren't the election treatment because the are positive beta lactamase. The diarrhea in children and immunocompromised or chronic patients will be treated with cotrimoxazole or fluorquinole.

[Acute infections caused by Epstein-Barr virus. Comparative study of various diagnostic methods]

Comparative performance of four methods (IFI, IgM anti-VCA, Organon Teknika; ELISA, IgM anti VCA, Incstar Corp and Pharmacia Diagnostic Inc; ELISA IgM against a group of several antigens which principal component is EBNA, Behring Institute) to detect antibodies (Abs) against Epstein-Barr virus in 180 patients (group 1) with infectious mononucleosis with no heterophil Abs (Organon Teknika), 180 healthy subjects with no heterophil Abs (group 2) and 20 patients with infectious mononucleosis (group 3) and with positive heterophil Abs, were studied. In group 1, 10% of patients had IgM Abs, without differences IgM Abs. In group 3 all patients had IgM Abs with no differences in the methods studied. There were no differences in the performance of the evaluated methods to detect IgM against different antigens, but those which use a group of antigens from the virus could be more useful in patients immunologic disorders.

In vitro immune modulation of polymorphonuclear leukocyte adhesiveness by sodium fluoride

We investigated the influence of sodium fluoride on polymorphonuclear leukocyte (PMN) adhesiveness in a healthy subject with low serum levels of fluoride. The PMN were separated from venous blood, and the percentages of adhered and unadhered cells were determined in vitro in plastic culture plates. The cells were cultured with five different fluoride concentrations ranging from 6.25 10(-2) microM to 4.0 microM in the presence and absence of autologous serum. PMN adhesiveness in both the presence and in the absence of autologous serum was 98.5%; the addition of fluoride had no effect on the results in the absence of serum. However, in the presence of autologous serum, PMN adhesiveness decreased significantly with the addition of fluoride (P < 0.05) from 0.5 microM. The decrease was smaller (1.1%) at a concentration of 0.125 microM, and larger at 12 times this concentration of fluoride (52.7%). We conclude that sodium fluoride reduces PMN adhesiveness in a dose-dependent manner. The effect is not direct, but should be modulated by a seric factor.

Changes in plasma glucagon, insulin and tissue metabolites associated with prolonged fasting in brown trout (Salmo trutta fario) during two different seasons of the year

1. Pyrenean brown trout juveniles (Salmo trutta fario) were fasted for 50 days in late winter (experiment 1) and summer (experiment 2). Plasma insulin, glucagon and glucose and some metabolites in plasma and in tissues were analysed. 2. Glucagon increased significantly on the 3rd day of fasting in the winter experiment (controls 653.7 +/- 92.4 pg/ml, fasted 912.7 +/- 135.2 pg/ml), and the same tendency was observed on the 5th day in the summer experiment (controls 430.5 +/- 56.2 pg/ml, fasted 555.5 +/- 95.3 pg/ml). During this initial period of fasting, plasma glucose was maintained in both experiments (75.5 +/- 4.7-67.6 +/- 4.1 mg/100 ml), but from day 8, glucose and glucagon decreased simultaneously. 3. Insulin decreased from the beginning of fasting, reaching lowest values after 50 days of fasting (winter experiment: controls 6.4 +/- 0.3 ng/ml, fasted 1.6 +/- 0.1 ng/ml; summer experiment: controls 4.8 +/- 0.1 ng/ml, fasted 1.2 +/- 0.2 ng/ml). Glucagon/insulin molar ratio (G/I) increased after 3 days in the winter experiment (controls 0.21 +/- 0.02, fasted 0.39 +/- 0.05), while in the summer experiment, the ratio rose from day 5 and reached a peak at day 30 (controls 0.16 +/- 0.02, fasted 0.48 +/- 0.07). 4. Muscle proteins were significantly mobilized after 50 days of fasting. Visceral index decreased significantly after day 15 while liver glycogen was already significantly lower at day 8. However, in the summer experiment, a transitory increase of liver glycogen was observed at day 30, coinciding with the peak of G/I.