[Aminoglycoside antibiotics neomycin and kanamycin inhibit the increase of of pyroglutamyl aminopeptidase activity by depolarizing synaptosomes of the frontal cortex of the rate]

INTRODUCTION

Thyrotrophin releasing hormone (TRH) has emerging in the last few years as a neuropeptide with important functions, not only as neurohormone into the hypothalamus-pituitary axis, but as neurotransmitter in several areas of the nervous system. Although little is known about its extra-endocrine functions, TRH has been related with several types of psychiatric disorders. Pyroglutamyl aminopeptidase (pGluAP) is the enzyme involved in the degradation of TRH.

OBJECTIVES

The present research studies the levels of pGluAP activity under basal (resting) and KCl-stimulated (depolarized) conditions. The role of intracellular free calcium homeostasis, by means of the aminoglycoside antibiotics neomycin and kanamycin as voltage-dependent calcium channels blockers, is also studied.

MATERIAL AND METHODS

Both pGluAP activity and intracellular free calcium concentration were analyzed in synaptosomes obtained from the frontal cortex of rats. Synaptosomes were incubated in artificial cerebrospinal fluid, under basal (resting) or KCl-stimulated (depolarized) conditions, with of without neomycin or kanamycin at different concentrations.

RESULTS

Depolarization increases significantly pGluAP activity, which is completely abolished by neomycin and kanamycin at the lower concentrations used. On the contrary, aminoglycoside antibiotics do not block completely the increase on intracellular free calcium concentration induced by depolarization. Under basal conditions, no changes were found on pGluAP activity nor intracellular free calcium.

CONCLUSIONS

pGluAP activity could regulate the neurotransmitter/neuromodulatory functions of TRH trough intracellular free calcium movements through aminoglycoside-sensitive voltage-dependent calcium channels. A role for inositol 4,5-bisphosphate breakdown products is also suggested.

Comparative distribution of glutamyl and aspartyl aminopeptidase activities in mouse organs

To evaluate the functional role of glutamyl and aspartyl aminopeptidases, their soluble and membrane-bound activities were measured simultaneously in several tissues of normal mice using arylamide derivatives as substrates. Although the soluble aspartyl aminopeptidase activity showed its highest levels in the testicle, the rest of the activities presented their highest levels in the kidney. Different patterns of distribution were observed for glutamyl and aspartyl aminopeptidase activities and also for soluble and membrane-bound aspartyl aminopeptidase activities. However no major differences were observed between soluble and membrane-bound glutamyl aminopeptidase activities. This unequal distribution suggests that the use of arylamide derivatives as substrates is a sensitive method that distinguishes between these enzymatic activities. The results also suggest different functions for soluble and membrane-bound aspartyl aminopeptidase activities, and for glutamyl and aspartyl aminopeptidase activities.

Influence of dietary supplementation with olive oil on pyroglutamyl-beta-naphthylamide hydrolysing activity in serum and different tissues of mice

Pyroglutamyl aminopeptidase is an omega peptidase which removes pyroglutamyl N-terminal residues from peptides and arylamide derivatives. To date, three distinct types of this enzyme have been described and called serum thyroliberinase, cytosolic pyroglutamyl aminopeptidase type I and membrane-bound pyroglutamyl aminopeptidase type II. The activity of all of them is thought to be involved in the regulation, more or less restricted in their substrate specificity, of various susceptible endogenous substrates such as TRH, GnRH, neurotensin, bombesin and anorexogenic peptide. It is well known that the type and amount of fat in the diet not only modify blood lipid concentrations, including cholesterol levels, but change the cell membrane lipid composition. Modifications in the composition and physical properties of the membrane lead to alterations in the activities of membrane-bound enzymes and carriers. The aim of this work was to compare the effect of a standard diet and a high fat diet (olive oil, 20% wt/wt) on pyroglutamyl-beta-naphthylamide hydrolysing activity, in serum and in soluble and membrane-bound fractions from different tissues of male mice. After ten weeks of feeding, pyroglutamyl-beta-naphthylamide hydrolysing activity was measured fluorometrically using pyroglutamyl-beta-naphthylamide as substrate. Mice fed the high fat diet had higher rates of body weight than controls starting from the second week of feeding. Serum total cholesterol concentrations were higher after feeding the high fat diet than after feeding the control diet. In serum, no changes were observed in the high fat group. In selected tissues, only pyroglutamyl-beta-naphthylamide hydrolysing activity was modified significantly in the soluble fraction, but not in the membrane-bound one, decreasing in the adrenal gland of high fat fed animals. The results may reflect functional modifications in susceptible endogenous substrates.

STAG3, a novel gene encoding a protein involved in meiotic chromosome pairing and location of STAG3-related genes flanking the Williams-Beuren syndrome deletion

Chromatin rearrangements in the meiotic prophase are characterized by the assembly and disassembly of synaptonemal complexes (SC), a protein structure that stabilizes the pairing of homologous chromosomes in prophase. We report the identification of human and mouse cDNA coding for stromalin 3 (STAG3), a new mammalian stromalin member of the synaptonemal complex. The stromalins are a group of highly conserved proteins, represented in several organisms from yeast to humans. Stromalins are characterized by the stromalin conservative domain (SCD), a specific motif found in all proteins of the family described to date. STAG3 is expressed specifically in testis, and immunolocalization experiments show that STAG3 is associated to the synaptonemal complex. As the protein encoded by the homologous gene (Scc3p) in Saccharomyces cerevisiae was found to be a subunit of a cohesin complex that binds chromosomes until the onset of anaphase, our data suggest that STAG3 is involved in chromosome pairing and maintenance of synaptonemal complex structure during the pachytene phase of meiosis in a cohesin-like manner. We have mapped the human STAG3 gene to the 7q22 region of chromosome 7; six human STAG3-related genes have also been mapped: two at 7q22 near the functional gene, one at 7q11.22, and three at 7q11.23, two of them flanking the breakpoints commonly associated with the Williams-Beuren syndrome (WBS) deletion. Since the WBS deletion occurs as a consequence of unequal meiotic crossing over, we suggest that STAG3 duplications predispose to germline chromosomal rearrangement within this region.

The cell cycle inhibitor p21 controls T-cell proliferation and sex-linked lupus development

Here we show that the cell-cycle regulator p21 is involved in immune system function. T lymphocytes from p21-/- mice exhibit significant proliferative advantage over wild-type cells following prolonged stimulation, but not after primary activation. Consistent with this, p21-deficient mice accumulate abnormal amounts of CD4+ memory cells, and develop loss of tolerance towards nuclear antigens. Similar to human lupus, female p21-deficient mice develop antibodies against dsDNA, lymphadenopathy, and glomerulonephritis, leading to decreased viability. These data demonstrate a specialized role for p21 in the control of T-cell proliferation, tolerance to nuclear antigens, and female-prone lupus. These findings could be the basis for new therapeutic approaches to lupus.

[In vitro study of the effect of ethanol on pyroglutamyl aminopeptidase activity in mouse synaptosomes under basal and stimulated conditions]

INTRODUCTION AND OBJECTIVE

Pyroglutamyl aminopeptidase (pGluAP) is an omega peptidase which removes pyroglutamyl N-terminals residues from peptides and arylamidase derivatives. This activity is thought to be involved in the regulation of several physiological mechanisms on the central nervous system. pGluAP can modulate various susceptible endogenous substrates such as thyrotrophin-releasing hormone (TRH). It is well known that TRH plays an important role in the modulation of the behavioral changes induced by ethanol and others drugs. The aim of this work was to study the in vitro effects of ethanol (25, 50 and 100 mM) on the pGluAP activity and its ability for modulating the TRH.

MATERIAL AND METHODS

pGluAP activity was measured in synaptosomes from cerebral cortex of mouse, using pyroglutamyl-beta-naphthylamide as substrate in basal and stimulated (K+ 25 mM) conditions, and in presence or absence of calcium on the buffer.

RESULTS

In basal conditions, ethanol produced an inhibition of the pGluAP activity in presence or absence of calcium, being this inhibition non dose-related. However, the stimulation with K+ 25 mM did not produce a modification of pGluAP activity in presence of calcium, but produced a light increase in absence of it. Depolarization in presence or absence of calcium and ethanol produced an inhibition of pGluAP activity, which changed in function of the ethanol concentration used.

CONCLUSIONS

Ethanol modifies pGluAP activity in basal conditions by a mechanism independent of calcium, but the changes observed after the stimulation with high K+ may be due to a calcium-dependent mechanism. These variations of pGluAP activity induced by ethanol, and their effects on their endogenous substrates, specially TRH, may be responsible for the behavioral changes associated to the alcoholism and mediated by TRH.

Aminopeptidase activities in breast cancer tissue

BACKGROUND

Endopeptidases such as cathepsins help determine the prognosis of breast cancer (BC). However, little information is available about the role in BC of aminopeptidases (APs), which have been implicated in the metabolism of several local hormonal factors.

METHODS

Using aminoacyl-beta-naphthylamides as substrates, we measured fluorometrically alanyl-AP, arginyl-AP, cystinyl-AP, glutamyl-AP, aspartyl-AP, and pyroglutamyl-AP activities in their soluble and membrane-bound forms in surgically removed BC tissue from which we separated samples of neoplastic, adjacent tumoral, and unaffected surrounding tissue.

RESULTS

Compared with unaffected tissue, neoplastic tissue had significantly higher activities of soluble alanyl-AP (553.9 +/- 82.8 vs 1615.2 +/- 183.0 pmol/mg protein; P <0.001), arginyl-AP (372.4 +/- 56.6 vs 1027.2 +/- 143.5 pmol/mg protein; P <0.001), and cystinyl-AP (74.8 +/- 10.0 vs 282.9 +/- 37.2 pmol/mg protein; P <0.001), and of membrane-bound arginyl-AP (457.7 +/- 97.9 vs 886.6 +/- 140.0 pmol/mg protein; P <0.01). However, membrane-bound aspartyl-AP activity was significantly lower in neoplastic tissue (17.3 +/- 1.4 vs 9.2 +/- 1.2 pmol/mg protein; P <0.05) and pyroglutamyl-AP activity was significantly lower in neoplastic and adjacent tissues (12.8 +/- 0.9 vs 7.0 +/- 1. 2 and 8.0 +/- 1.3 pmol/mg protein; P <0.001 for both comparisons).

CONCLUSIONS

The present results document changes in AP activities in BC tissue. These changes may reflect the functional status of the AP substrates, which can be selectively activated or inhibited locally in the affected tissue as a result of specific conditions brought about by the tumor.

[The influence of oleic acid on the aminopeptidase activity in astrocytes of the rat]

INTRODUCTION

Changes in fatty acid composition of membrane lipids induce modifications on the activity of several enzymes and membrane transporters. Glial cells possess aminopeptidases which are located in the plasma membranes. Aminopeptidases are generally zinc-metalloenzymes which hydrolyze peptide bonds near the N-terminal end of peptides and polypeptides. The importance of these enzymes is based on their major role in protein metabolism and in the regulation of circulating hormones and biologically active peptides.

OBJECTIVE

We study the effects of oleic acid on several aminopeptidase activities in primary cultures of rat astroglia, using aminoacyl-beta-naphthylamides as substrates.

RESULTS

Oleic acid inhibits Ala-, Cys-, Leu- and Tyr-aminopeptidase activities, but not modifies Arg- and pGlu-aminopeptidase activities.

CONCLUSIONS

Oleic acid modulates aminopeptidase activities in astrocytes. This could be related with intercellular communication and molecular transport processes, in which the astrocyte function has been involved. Furthermore, oleic acid might modulate the action of opioid peptides and steroid hormones on astroglial cells.

Changes in membrane-bound leucine aminopeptidase activity during maturation and ageing of brain

Aminopeptidases are believed to be enzymes that regulate the activity of various neuropeptides. However, their physiological role, as well as their mechanisms of regulation, are not well understood. To analyze a part of the regulatory mechanisms that control the activity of these enzymes, the subcellular distribution of membrane-bound leucyl aminopeptidase activity was studied in rat brain during development and ageing. Except in fetuses, the enzymic activity was greatest in the microsomal fraction in all ages tested. Except in microsomal and myelin fractions, compared with fetuses, leucyl aminopeptidase activity showed a decrease in 1-week-old rats and a subsequent increase to adult levels in 1-month-old rats. This profile differed in the microsomal fraction, where the activity increased steadily up to 1-month-old rats. After this age, the activity decreased progressively in 5-month and 24-month-old rats. These results may reflect changes in the functional status of the susceptible substrates during development and ageing.

Synthesis and anti-HIV-1 activities of new pyrimido[5,4-b]indoles

A set of new pyrimido[5,4-b]indole derivatives that are structurally related to some non-nucleside HIV-1 reverse transcriptase inhibitors were synthesized and biologically evaluated for their activity as inhibitors of wild and mutant HIV-1 RT types in an 'in vitro' recombinant HIV-1 RT screening assay, as well as anti-infectives in HLT4lacZ-1IIIB cells. Preliminary structure-activity relationships suggest that activity is promoted by simultaneous substitution in positions 2 and 4, especially when chains of alkyldiamine type are present, and by electron-releasing substituents (methoxy) in positions 7 and 8. The inactivity or the very low activity of title derivatives does not suggest interest in AIDS therapy.

Lateralization of aminopeptidase A activity in substantia nigra, striatum and frontal cortex of rats

Several brain aminopeptidase activities have been reported to be asymmetrical, but no direct correlation with lateralized functions has been proposed. Cholecystokinin (CCK) coexists with dopamine (DA) in the nigrostriatal system, which is involved in lateralized motor behaviors. Because aminopeptidase A activity is probably responsible for the hydrolysis of CCK, we studied the left-right distribution of glutamate- (GluAP) and aspartate-aminopeptidase (AspAP) activities in their soluble (Sol) and membrane-bound (M-B) forms in the substantia nigra, striatum and cortex of rats. Although there was a highly significant predominance of the left side in the substantia nigra and striatum for Sol GluAP and M-B AspAP respectively, in the frontal cortex predominance was on the right side for M-B AspAP. These results suggest a relationship between aminopeptidase A activity and lateralized nigro-striato-cortical functions involving CCK.

Eosinophil soluble protein levels, eosinophil peroxidase and eosinophil cationic protein in asthmatic patients

Eosinophil granular proteins are useful eosinophil activation markers in asthmatic patients. In this study, eosinophil peroxidase (EPO) and eosinophil cationic protein (ECP) levels were assessed in different stages of bronchial asthma in 123 patients suffering from intrinsic (n = 42) and extrinsic (n = 81) asthma, with the aim of evaluating the difference in the protein levels between both types of asthma and their importance as a severity marker of the disease. The geometric mean serum level of EPO was 12.3 +/- 2.17 ng/ml (mean +/- SD) in controls, and 38.6 +/- 3.4 ng/ml in the asthmatic patients. Mean ECP levels were 13.22 +/- 1.11 ng/ml in controls and 30.5 +/- 2.38 ng/ml in patients. Depending on the asthma severity, the EPO levels were 30.4 +/- 4.35, 38.7 +/- 5.29, and 54.46 +/- 9.46 ng/ml in mild, moderate and severe asthmatics, respectively, with the differences being significant between the groups of patients with mild and severe asthma (p < 0.001). ECP levels were 24.23 +/- 3.37 in mild, 31.69 +/- 4.21 in moderate, and 37.61 +/- 4.52 ng/ml in severe asthma. There were significant differences in ECP levels between mild and moderate asthma (p < 0.001) and between mild and severe asthma (p < 0.001). Peripheral eosinophil count was 157 +/- 20 eosinophils/mm3 in controls, 334 +/- 35 eosinophils/mm3 in mild asthmatics, 510 +/- 87 eosinophils/mm3 in moderate asthmatics and 658 +/- 72 eosinophil/mm3 in severe asthmatics, with significant differences between all groups (p < 0.05-p < 0.001). Serum EPO and ECP levels and peripheral eosinophil count were significantly greater in patients with active asthma than in patients with silent asthma (p < 0.001). Significant negative correlations (p < 0.001) were found between serum EPO levels and FEV1 (rs = -0.30), MEF25-75 (rs = -0.33), MEF50 (rs = -0.34). There was also a significant (p < 0.001) and negative correlation between ECP levels and FEV1 (rs = -0.31), MEF25-75 (rs = -0.31), MEF50 (rs = -0.32). A good positive correlation was found between peripheral eosinophil count and EPO levels (rs = 0.80, p < 0.001), and ECP levels (rs = 0.67, p < 0.001). We also found a significant positive correlation between clinical score and peripheral eosinophil count (rs = 0.54, p < 0.001), EPO levels (rs = 0.46, p < 0.001) and ECP levels (rs = 0.52, p < 0.001).

Effect of immunotherapy on allergen-specific production of sulphidoleukotriene and histamine

Numerous controlled trials have demonstrated the efficacy of specific immunotherapy, although its mechanism is not completely understood. Few studies have addressed the effects of immunotherapy on the release of mediators. We measured in vitro sulphidoleukotriene (sLT) and histamine release after specific stimulus (Dermatophagoides pteronyssinus or Lollium perenne) in a group of patients under immunotherapy (n = 35) and compared the results with those obtained in a group of allergic patients without immunotherapy (n = 57). SLT quantification was carried out by cellular stimulation allergen test (CAST)-ELISA and we measured the amount of histamine release using a fluorometric method. We found a significant (p < 0.05) reduction of allergen-specific mediator release on the group of patients under immunotherapy treatment. When we studied the group of patients sensitive to D. pteronyssinus we also observed a significant reduction in sLT release after the in vitro stimulus with anti-IgE. In vitro sLT production could be a good marker for follow-up immunotherapy. This study provides more evidence to support the immunological and cellular changes induced by immunotherapy.

Growth hormone reduces mortality and bacterial translocation in irradiated rats

Growth hormone stimulates the growth of intestinal mucosa and may reduce the severity of injury caused by radiation. Male Wistar rats underwent abdominal irradiation (12 Gy) and were treated with either human growth hormone (hGH) or saline, and sacrificed at day 4 or 7 post-irradiation. Bacterial translocation, and the ileal mucosal thickness, proliferation, and disaccharidase activity were assessed. Mortality was 65% in irradiated animals, whereas hGH caused a decrement (29%, p < 0.05). Bacterial translocation was also reduced by hGH (p < 0.05). Treating irradiated rats with hGH prevented body weight loss (p < 0.05). Mucosal thickness increased faster in irradiated hGH-treated animals. The proliferative index showed an increment in hGH-treated animals (p < 0.05). Giving hGH to irradiated rats prevented decrease in sucrose activity, and increment in lactase activity. In conclusion, giving hGH to irradiated rats promotes the adaptative process of the intestine and acute radiation-related negative effects, including mortality, bacterial translocation, and weight loss.

Sex differences and age-related changes in human serum aminopeptidase A activity

Given that aminopeptidase A is primarily responsible for cleaving aspartic acid and converting angiotensin II to angiotensin III, the purpose of the present study was to evaluate the activity of aminopeptidase A by determination of glutamate aminopeptidase activity (GluAP) and aspartate aminopeptidase activity (AspAP) (reported respectively as aminopeptidase A and angiotensinase A activities) in human serum during development and ageing, in an apparently healthy population of 139 male and 148 female subjects. To measure GluAP and AspAP we used glutamyl- and aspartyl-2-naphthylamide as substrates. Significant age-related increases were observed in GluAP activity in males and females and in AspAP activity in females. In males, there were no age-related differences in AspAP activity. A significant correlation was observed between age and GluAP activity in the population analysed as a whole or according to sex. No correlation was demonstrated between age and AspAP activity either in the whole population or according to sex. These results may reflect the evolution of the functional status of susceptible circulating substrates during development and ageing.

In vitro antigen-specific sulphidoleukotriene production in patients allergic to Dermatophagoides pteronyssinus

BACKGROUND

Sulphidoleukotrienes (slt) are important mediators in allergic diseases that are synthesized after allergen-specific stimulation.

OBJECTIVES

The aim of this study is to determine in vitro slt production after allergen-specific (Dermatophagoides pteronyssinus) stimulus of peripheral blood leucocytes and to observe whether histamine release in whole blood with the same allergen correlates with slt production. We also wanted to evaluate whether a correlation exists between the release of slt and histamine and other diagnostic procedures as well as various clinical situations.

METHODS

We studied 62 patients sensitive to Dermatophagoides pteronyssinus (Der p), 30 atopic controls and 12 healthy donors. We determined slt production using the CAST-ELISA technique and histamine release using two concentrations of Der p extract (20 and 2 ng/mL). We also carried out quantification of specific and total IgE levels, skin tests and pulmonary function test on each patient.

RESULTS

We observed a significantly increased slt release after in vitro stimulation with Der p. There was a significant difference in the slt release between controls and sensitive patients (P < 0.001) and between atopic controls and sensitive patients (P < 0.001). The data are similar to those obtained with histamine release. We noted a positive correlation (P < 0.001) between slt and histamine release (r = 0.71, at 2 ng/mL and r = 0.83 at 20 ng/mL). We also found a positive (P<0.001), although weak (r=0.4 with at 2ng/mL, and r = 0.34 with P = 0.003 at 20 ng/mL) correlation between slt release and specific IgE levels as well as between slt release and skin-test reactivity (r = 0.49 at 2 ng/mL and r = 0.45 at 20 ng/mL; P < 0.001). No significant correlation between slt release and asthma severity was observed, although a trend toward higher slt production in severe and moderate asthma was detected. We found a significant (P<0.001) but weak (r=-0.3) negative correlation between age and slt release. With respect to sex-related differences, we found significant differences (P < 0.05) in slt release between the sexes with a higher slt release in men than in women.

CONCLUSION

We conclude that CAST-ELISA for quantification of slt production is a useful in vitro method for diagnosing sensitization to Der p. There also exists a close correlation between slt release and other parameters of allergic sensitization in vitro as well as in vivo.

Growth hormone reduces bacterial translocation in radiation enteritis in the rat

BACKGROUND

Radiotherapy may be considered as one of the most effective treatments for digestive tumours. This procedure has major side effects, especially in fast growing tissues like intestinal mucosa. The administration of drugs that reduce or avoid radiation injury of the intestinal mucosa may be clinically advantageous. Growth hormone is a peptide suitable for this purpose by modifying cell proliferation within the intestinal crypt.

MATERIAL AND METHOD

Adult male Wistar rats were used in a model of abdominal irradiation. Each irradiated animal received 1200 cGy under anaesthesia and was sacrificed four and seven days later. The animals were treated with either saline or growth hormone (1 mg/kg/day) beginning immediately after the irradiation treatment. On the day of sacrifice, intestinal samples were taken for morphometric measurements and mesenteric lymph nodes for bacterial translocation.

RESULTS

Mortality was of 50% approximately and was not affected by growth hormone treatment in irradiated animals. Bacterial translocation increased (p < 0.05) in irradiated animals whereas no significant increase was observed in rats treated with growth hormone. Growth hormone promotes an earlier growth of intestinal villi in irradiated animals (p < 0.05).

CONCLUSIONS

Growth hormone promotes the morphologic adaptation of intestinal mucosa after abdominal irradiation, reducing bacterial translocation in rat.

Activities of aminopeptidases in a rat saline model of volume hypertension

Aminopeptidase activity plays a role in the metabolism of several peptides that could be involved in blood pressure control. This activity has been implicated in the pathogenesis of hypertension, essentially in spontaneously hypertensive rats. However, few studies have examined aminopeptidase activities in animal models other than genetic hypertension. To analyze the aminopeptidase response to the specific conditions of the reduced renal mass saline model of arterial hypertension, aminopeptidase A activity (glutamyl- and aspartyl-aminopeptidase), aminopeptidase M activity (alanyl-aminopeptidase), aminopeptidase B activity (arginyl-aminopeptidase), pyroglutamyl-aminopeptidase and cystinyl-aminopeptidase were measured in the neurohypophysis, in the adrenal gland and in serum of this model of hypertension. In the neurohypophysis, there was a significant increase of soluble cystinyl-, alanyl-, arginyl-, pyroglutamyl- and membrane-bound aspartyl-aminopeptidase activities in hypertensive animals. In the adrenal gland, soluble cystinyl-, alanyl-, arginyl- and pyroglutamyl-aminopeptidase activities were also higher in hypertensive rats than in normotensive controls. No differences were found in serum levels of aminopeptidase activities between both groups of animals. A highly significant positive correlation between the neurohypophysis and the adrenal gland was observed for soluble cystinyl- and alanyl-aminopeptidase activities in the model of hypertension, whereas no correlation was observed in normotensive rats. Our results suggest that aminopeptidase activities could be involved in the regulatory response to the reduced renal mass hypertension and also suggest a coordinate response between the adrenal gland and the neurohypophysis, to the specific metabolic conditions of this model of hypertension.

Morphometric and proliferative effects of growth hormone on radiation enteritis in the rat

Radiation enteritis is a common occurrence after radiotherapy in patients with abdominal tumors. Growth hormone may modify the response of the intestinal mucosa to radiation through its effects on the cell cycle or by increasing cell mass. The aim of this study is to determine the effects of growth hormone in the radiation-induced morphoproliferative changes in the intestinal mucosa.

MATERIAL AND METHODS

An intestinal mucosal lesion was induced in adult male Wistar rats by means of abdominal irradiation with a lethal dose (LD50) of 1200 cGy. All animals received treatment with either saline or growth hormone for 7 days after irradiation. The animals were sacrificed on day 7. Body weight was determined the morphoproliferative status of the intestinal mucosa was assessed and the disaccharidase activity was measured.

RESULTS

Growth hormone reduced body weight loss and increased mucosal length in irradiated rats. Mucosal proliferation was incremented in both irradiated and nonirradiated growth hormone-treated rats. Disaccharidase activity levels were similar to or higher than control values in all treated groups.

CONCLUSION

Administration of growth hormone to irradiated rats reduces intestinal injury, probably as a consequence of an earlier recovery of intestinal morphology and functional status.

Study of IgE-dependent sulphidoleukotriene cellular releasability

Cellular releasability of mediators, as termed by Lichtenstein and Conroy (1), can be triggered by interaction with allergens, anti-IgE antibodies or other agonists. Genetic factors can also influence the cell releasability. We studied 104 subjects, including 92 atopic patients (62 sensitive to D. pteronyssinus and 54 sensitive to Lolium perenne) and 12 healthy controls. Sulphidoleukotriene (sLT) production was measured after allergen and anti-IgE stimulus with CAST-ELISA, and histamine release using a fluorometric method. We found a significant sLT production after anti-IgE stimulation, higher than in basal conditions with medium alone. The sLT production was also significantly higher in sensitive patients than in healthy controls. We found 14.5% of healthy and atopic subjects to be non-responders to anti-IgE stimulus. We also found a positive and significant correlation between sLT production and histamine release. Moreover, we observed a significant positive correlation between IgE-dependent and antigen-specific sLT release. We also noticed a decrease in sLT production and a decrease in histamine release with aging. Male patients had a sLT production significantly higher than female patients. With respect to clinical diagnosis, the group of patients with rhinitis had the highest mediator production. Finally, pollinic patients studied during the spring had a higher sLT production to anti-IgE than those studied out of this season. We conclude that quantification of sLT production after anti-IgE stimulation is a useful method to study cell releasability of mediators and that such releasability is higher in atopic patients than in healthy donors. We must emphasize the usefulness in allergy diagnosis of relying not only on the use of methods demonstrating the existence of sensitization to an allergen, but also of techniques able to quantify the ability to respond to that allergen. In this way we would be able to evaluate the clinical and immunological evolution of patients and to follow up the efficacy of their treatment.

Sex differences and in vitro effects of steroids on serum aminopeptidase activities

We studied the possible existence of physiological sex differences in serum aminopeptidase activities in mice, by evaluating the effect of gonadectomy and the in vitro response to the presence in the medium of cholesterol or steroid hormones. Alanyl- and glutamyl-aminopeptidase activities were measured in sera from male, female, orchiectomized and ovariectomized mice, incubated with substrate solutions, and compared with the same groups of serum incubated with substrate solutions including cholesterol, 17-beta-estradiol, testosterone, progesterone or hydrocortisone. Our results demonstrated highly significant sex differences, and an influence of cholesterol and steroid hormones on aminopeptidase activity. Depending on the nature of the aminopeptidase, these enzymes responded in different ways to the presence of these substances and also responded differently to gonadectomy. For alanyl-aminopeptidase activity, but not for glutamyl-aminopeptidase activity, there was a clear difference in response between males and females to incubation of the serum with steroid hormones.

Renal aminopeptidase activities in animal models of hypertension

Aminopeptidase activity (AP) has been implicated in the metabolism of renal and circulating vasoactive peptides. This activity is involved in the pathogenia of hypertension, essentially in spontaneously hypertensive rats. However, no other animal models, which develop hypertension by other different ways, have been used to study the possible role of aminopeptidase activity. To investigate the role of this activity in the pathogenesis of hypertension, angiotensinase A activity (glutamyl-AP and aspartyl-AP), aminopeptidase M activity (alanyl-AP), aminopeptidase B activity (arginyl-AP), pyroglutamyl-AP, and cystinyl-AP were measured in the serum and kidney of two experimental animal models of renovascular hypertension: Goldblatt two-kidney one clip (G2K-1C) and low renal mass rats (LRM). No differences were found in serum levels of AP in LRM or G2K-1C in comparison with their respective controls. In LRM rats there was a significant decrease in membrane-bound angiotensinase A (glutamyl-AP), arginyl-AP and alanyl-AP activities. In G2K-1C rats there was a significant decrease in soluble and membrane-bound angiotensinase A activity (aspartyl-AP). Our results suggest that AP activities play a role in the regulation of renal vasoactive peptides, and respond differently depending on the cause of hypertension.

Catheter-assisted totally thoracoscopic coronary artery bypass grafting: a feasibility study

BACKGROUND

The purpose of this study is to examine the feasibility of performing totally thoracoscopic internal mammary-to-coronary artery bypass grafting with the assistance of radiologically guided catheter intervention.

METHODS

Fourteen dogs were subjected to mobilization of the internal mammary artery and anastomosis of it to the left anterior descending coronary artery over an angiographic catheter inserted into the internal mammary artery under fluoroscopy. The anastomosis was completed over the catheter using sutures and the application of fibrin glue. Eight animals underwent the anastomosis after their sacrifice. The other 6 animals were put on closed chest cardiopulmonary bypass and had their anastomosis done after intraaortic balloon occlusion and cardioplegic arrest of the heart. All animals had an angiographic and pathologic examination at the completion of the anastomosis.

RESULTS

Anastomosis was completed in all dogs. Three anastomoses leaked and two were noted to be stenosed at completion of the anastomosis. One leak was sealed by application of fibrin glue. Both stenotic anastomoses were caused by suturing of the back wall when a short angiographic catheter could not be positioned across the anastomosis.

CONCLUSIONS

Minimally invasive totally thoracoscopic mammary-to-coronary artery bypass grafting with catheter assistance is feasible. Technical improvement and appropriate instrumentation are required to minimize anastomotic failure.

SA-1, a nuclear protein encoded by one member of a novel gene family: molecular cloning and detection in hemopoietic organs

We report the molecular cloning of a novel gene family. The first member of this family was cloned from a mouse lambda gt11 cDNA library using the B92 monoclonal antibody (mAb) raised against stromal cell extracts. This was followed by RACE-PCR using mRNA from the stromal cell line. A 4 kb cDNA was obtained encoding a unique protein sequence of 1258 aa, that we designate stromal antigen (SA)-1. The human SA-1 gene was cloned by homology from a thymus cDNA library and the sequence of the predicted protein was found to be highly homologous to the murine SA-1 (>98.9%). Another cDNA was cloned and the deduced protein (SA-2) was 71% homologous to SA-1. Northern blot and PCR analysis indicated that on the mRNA level the SA-1 gene is expressed in all tissues analyzed and probably encodes a single transcript. The identification of SA-1 protein in tissues and cells required combined immunoprecipitation and Western blotting using a polyclonal antiserum raised against a predicted peptide of SA-1 and the B92 mAb. Using this assay we identified a protein of about 120 kDa in hemopoietic organs. Subcellular fractionation indicated that SA-1 is a nuclear protein. Thus, despite the ubiquitous expression on the mRNA level, the protein was predominantly detected in hemopoietic organs and may therefore be controlled on a post-transcriptional level. The SA-1 gene described in this study is highly conserved between mouse and man. This implies a crucial function for this protein.

Cross-reactivity of Olea europaea with other Oleaceae species in allergic rhinitis and bronchial asthma

Cross-reactivity between pollen extracts of four species of Oleaceae was studied: olive (Olea europaea), ash (Fraxinus excelsior), privet (Ligustrum vulgare), and lilac (Syringa vulgaris). Thus, 51 patients and 13 atopic controls were studied, by means of intracutaneous skin tests, histamine-release tests against the four extracts, and specific IgE to O. europaea. The proteic content of the four extracts was assessed by SDS-PAGE and immunoblotting, and similarity of all the extracts studied was observed after electrophoresis and immunodetection. Six common bands were found to be responsible for the cross-reactivity, with apparent molecular weights of 49.6, 40, 36.7, 19.7, 16.7, and 14 kDa, respectively. The cross-reactivity was also corroborated by immunoblotting inhibition and FEIA inhibition. The patients had a similar response to the four allergenic extracts used, although the response to Olea was greatest. When the patients were compared by their geographic origin (northern or southern Spain, according to the distribution of areas of olive pollen influence), there were no significant differences between the two groups in skin reactivity, but a higher histamine release was observed for the four extracts in the southern group, although it was significant only for Fraxinus and Ligustrum. This work corroborated the practicality of the diagnostic methods used and the cross-reactivity between the four species studied, as demonstrated by the different methods used. Therefore, we suggest that only O. europaea extract be used in diagnosis and immunotherapy in Oleaceae pollen allergy.

[Dorsal subdural spinal abscess after epidural anesthesia]

Spinal subdural empyema (SE) is a rare condition. We describe a young patient with a torathic SE after lumbar epidural anaesthesia. SE was distant from the region of manipulation. Spinal magnetic resonance was the most useful procedure for diagnosis and follow-up. Treatment with intravenous antibiotics and drainage was not enough, and she needed complete surgical excision of the lesion.

Serum eosinophil peroxidase (EPO) levels in asthmatic patients

Eosinophil granular proteins are a useful eosinophilic activation marker in asthmatic patients. In this study, the eosinophil peroxidase (EPO) levels were assessed in different stages of bronchial asthma, in 123 patients suffering from asthma, classified as mild (n =49), moderate (n = 49), and severe (n = 25), according to the International Consensus Report of Diagnosis and Treatment of Asthma, as well as in 27 healthy controls, with the aim of evaluating the importance of this protein as a severity marker in bronchial asthma, and its possible correlation with parameters such as anamnesis, respiratory function tests, and peripheral blood eosinophil count, and also with some allergologic diagnostic tests, both in vivo and in vitro. The geometric mean serum level of EPO was 9.3 +/- 11.3 ng/ml (median +/- SD) in controls, 28 +/- 37.8 ng/ml in the asthmatic patients. Depending on the asthma severity, the EPO levels were 25 +/- 30.5; 29 +/- 37.1, and 41 +/- 47.3 ng/ml in mild, moderate, and severe asthmatics, respectively, being the significant differences between the group of patients with mild and severe asthma (P < 0.001). The number of eosinophils (eos) in peripheral blood was 157 +/- 20 eos/mm3 in the controls, 334/35 eos/mm3 in mild asthmatics, 510 +/- 87 eos/mm3 in moderate asthmatics, and 658 +/- 72 eos/mm3 in severe asthmatics, with significant differences between all groups (from P < 0.05 to P < 0.001). Both the serum levels of EPO and the number of eosinophils were greater in patients with active asthma patients with inactive asthma (P < 0.001). Significant negative correlations (P < 0.001) were found between serum levels of EPO and FEV1 (rs = 0.30), MEF25-75 (rs = -0.33) and MEF50 (rs = -0.34), and a good positive correlation (rs = 0.80, P < 0.001) was found between EPO levels and the number of eosinophils in peripheral blood. We also found a significant positive correlation between eosinophil number and clinical score (rs = 0.54, P < 0.001) and between EPO levels and the mentioned score (rs = 0.46, P < 0.001).

Synthesis and evaluation of new Reissert analogs as HIV-1 RT inhibitors. 2. Benzo[f]quinoline and pyridine derivatives

The synthesis and preliminary evaluation of new benzo[f]quinoline and pyridine derivatives, obtained by application of the Reissert method and its modifications, as HIV-1 RT inhibitors and anti-infectives are presented. The most active products against HIV-1 RT wild type are the ethyl 2-cyano-1,2-dihydrobenzo[f]quinoline-1-carboxylate 2b, propyl 2-cyano-1,2-dihydrobenzo[f]quinoline-1-carboxylate 2c, and 2-cyano-1-(2'-furoyl)-1,2-dihydrobenzo[f]quinoline 2n, which maintain their activity against the mutant type P236L, resulting inactive against the Y181C type. Using the data previously obtained by our research team for analogous series derived from quinoline as reference, the compounds which have now been obtained present an increase in the cytotoxic character attributable to the introduction of a benzene ring fused with the quinoline base nucleus, as well as a decrease of the activity as HIV-1 RT inhibitors when the quinoline benzenic ring is eliminated.

Synthesis and evaluation of new Reissert analogs as HIV-1 reverse transcriptase inhibitors. 1. Quinoline and quinoxaline derivatives

The synthesis and preliminary evaluation of new quinoline and quinoxaline derivatives (obtained by applying the original Reissert method, conveniently modified) as HIV-1 Reverse Transcriptase (RT) inhibitors are presented in this paper; likewise, the first structure-activity relationships are also proposed. Propyl 2-cyano-1(2H)-quinolin-carboxylate 2e, isopropyl 2-cyano-1 (2H)-quinolincarboxylate 2f, butyl 2-cyano-1 (2H)-quinolincarboxylate 2g and isobutyl 2-cyano-1 (2H)-quinolincarboxylate 2h have been selected as lead compounds. These compounds are active against the HIV-1 RT mutant type P236L (2f, IC50 = 1.2 microM) and present activity as anti-infective agents in HLT41acZ-1IIIB cells, showing no cytotoxicity at the active concentrations.

[Subcellular distribution of leucine aminopeptidase during the development and aging of rat brains]

INTRODUCTION

The aminopeptidases are considered to be enzymes which can regulate the activity of various neuropeptides. However, their precise function has not yet been fully determined.

OBJECTIVE

With a view to studying the function of these enzymes at the cerebral level, the subcellular distribution of soluble leucine aminopeptidase from left and right cerebral hemisphere, in rats of different pre-natal and post-natal ages was determined as described in this paper.

MATERIALS AND METHODS

The activity of soluble leucine aminopeptidase was determined fluorimetrically in the sub-cellular fractions obtained from the left and right cerebral hemispheres of rats of different pre-natal and post-natal ages: fetuses (of 19-21 days gestation), 1 week, 1, 5 and 24 months of age.

RESULTS

No differences were observed between the cerebral hemispheres at any of the ages studied. However, significant differences were seen in the evolutionary behaviour of the two hemispheres. At all ages, except 24 months, there were significant differences between the fractions. In the fetuses, most activity was seen at the level of the synaptosomal raw fraction and least in the microsomal. At 1-week-old, the highest levels were seen at a microsomal level. In rats of 1 and 5 months of age, the highest levels were detected at synaptosomal level. With regard to the evolution with age, in the homogenate, nuclear fraction, cytosol and mitochondrial fraction a similar profile was observed, with a decrease after birth and an increase at one month, being stable at the other ages. At a synaptosomal level the profile is similar, although the differences are much more marked, with a drastic decrease in activity at two years of age. By contrast, the microsomal fraction showed a very different evolutionary profile with an increase after birth, becoming stable at later ages.

CONCLUSIONS

The activity of soluble leucine aminopeptidase shows a heterogeneous subcellular distribution together with significant differences during cerebral development and ageing. The behaviour of this enzyme may reflect the functional state of its neuropeptide substrates.

Antigen-specific sulphidoleukotriene production and histamine release in pollinic patients

We studied sulphidoleukotriene (sLT) production, by means of CAST-ELISA (Bühlmann) in 92 atopic (54 pollinic and 38 non-pollinic) patients, and in 9 control subjects, after antigenic stimulation of peripheral blood leukocytes with 20 ng/ml and 2 ng/ml of Lolium perenne pollen extract, in the presence of IL-3. Antigen-specific stimulation of leukocytes from pollinic patients studied during the pollen season led to a sLT production significantly higher (p = 0.03 at 2 ng allergen/ml) than in those studied out of the pollen season. Histamine release was also significantly higher in pollen season than out of the season (p = 0.04 at 20 ng allergen/ml and p < 0.001 at 2 ng allergen/ml). There was a significant positive correlation between sLT production and histamine release (r = 0.67 at 2 ng allergen/ml and r = 0.57 at 20 ng/ml, both p < 0.001), and between sLT production and skin test results (r = 0.5 at 2 ng allergen/ml and r = 0.46 at 20 ng allergen/ml, both p < 0.001). We found that sLT production was lower, although not significantly, in patients older than 40 years, and histamine release was significantly (p = 0.02) higher in women than in men at 2 ng allergen/ml. We conclude that sLT production in pollinic patients is higher when antigenic pressure is increased in the environment, and that sLT quantification by CAST-ELISA might be useful for evaluation of this sensitization, with analogous results to the histamine release test.

Developmental changes of soluble and membrane-bound aspartate aminopeptidase activities in rat brain

Specific soluble and membrane-bound aspartyl-naphthylamide hydrolyzing activities were assayed in brain subcellular fractions from rat fetuses (19-20 days of gestation), and from 1-week-old and 1-, 5- and 24-month-old rats. Both enzymatic activities showed a heterogeneous distribution, with highest concentrations mainly in the microsomal fraction. Membrane-bound activity was in most cases higher than soluble activity. With the exception of soluble activity in the nuclear and microsomal fractions, significant age-related changes were observed in all fractions for both enzymatic activities. Soluble activity showed a homogeneous developmental profile in most of the fractions, with the lowest levels in 1-month-old rats and the highest in 1-week and 5-month-old animals. However, changes in the microsomal fraction did not follow the pattern displayed by the rest of the fractions. No clear developmental profile in specific membrane-bound activity was observed, each fraction exhibiting a different sequence of changes. Whereas in 24-month-old-rats there was a significant increase in activity in homogenate, nuclear and microsomal fractions, a significant decrease was observed in the synaptosomal fraction. These results may reflect the functional status of the endogenous substrates of the enzymes.

Pyroglutamyl peptidase I levels and their left-right distribution in the rat retina and hypothalamus are influenced by light-dark conditions

To evaluate the effects of light and darkness on pyroglutamyl peptidase I activity (pGluPI) and its left-right distribution, pGluPI was measured bilaterally in the retina and hypothalamus under selected light-dark schedules. Rats under a 12 h light-dark cycle were divided into four experimental groups. After the end of the 12 h dark period, the animals were kept two additional hours in darkness (group 1), or light (group 2). After the end of the 12 h light period, the animals were kept two additional hours in darkness (group 3), or light (group 4). Experiments were done in light or darkness depending on the 2 h period. In the retina, a previous 12 h light period led to higher values of enzyme activity than dark periods. Left-right predominance, however, depended on the previous 2 h period: the light period led to left predominance, whereas right predominance was found after the 2 h dark period. In the hypothalamus, a left predominance was found only in group 3. These results demonstrate that environmental light conditions influence pGluPI activity in the rat retina and hypothalamus.

Further insights on the inhibition of HIV type 1 infection in vitro by CD4-modified synthetic peptides containing phenylalanine

Phenylalanine-containing peptides from CD4 were synthesized on the basis of chemical similarity with active CD4(81-92)-benzylated peptides. Systematic replacement of amino acids of these peptides bearing the benzyl group by phenylalanine, afforded several peptides that were able to block the binding of gp120 to CD4 and to inhibit HIV-induced syncytium formation. These experiments showed that substitution of residues 81 and 85 by phenylalanine was the most important for activity. Following optimization of the length of phenylalanine-substituted peptides it was found that FYICFVED and FYICFVEDE were the most active. Their IC50 for the inhibition of syncytium formation was around 1.2-1.6 microM. This activity is at least 30 times higher than that of the parent peptide FYIFFVEDQKEEDD previously reported (Lasarte et al., J Acquir Immune Defic Syndr 1994;7:129-134). Binding competition experiments with two different anti-peptide antisera recognizing the V3 region of gp120 and FYICFVEDE, show that the active peptides bind to V3 or to a sterically near region of V3. None of the active peptides was toxic to cells in vitro. The enhanced activity and simplicity of these new phenylalanine-substituted CD4 peptides might be a good starting point for the development of mimotopes of potential use for the treatment of AIDS.

Serum ECP levels in asthmatic patients: comparison with other follow-up parameters

In recent years, eosinophil cationic protein (ECP) has been considered as a useful eosinophilic activation marker in asthmatic patients. In this study, serum ECP levels in different stages of bronchial asthma were evaluated. We studied 123 patients suffering from asthma, which was classified as mild (n = 49), moderate (n = 49), severe asthma (n = 25), and also 31 healthy controls. Serum ECP levels were 13.22 +/- 1.11 ng/mL (mean +/- s.e.m.) in controls, and 30.15 +/- 2.38 ng/mL in asthmatic patients. By subgroups, ECP levels were 24.23 +/- 3.37 ng/mL, 31.69 +/- 4.21 ng/mL and 37.61 +/- 4.52 ng/mL, in mild, moderate and severe asthmatic patients, respectively, being the differences among the three groups statistically significant (P < 0.01-P < 0.001). Peripheral blood eosinophil numbers were 157 +/- 20 eos/mm3 in controls, and 334 +/- 35 eos/mm3, 510 +/- 87 eos/mm3, and 658 +/- 72 eos/mm3, in mild, moderate, and severe asthmatic patients, respectively, with significant differences among all groups (P < 0.05-P < 0.001). The serum ECP levels as well as the eosinophil numbers were higher in symptomatic patients than in the asymptomatic ones (P < 0.01). Moderate negative correlations, although highly significant (P < or = 0.001), were found between serum ECP levels and forced vital capacity (FVC) (rs = -0.27), FEV1, MEF25-75 (rs = -031), and MEF50 (rs = -0.32). There was also a good positive correlation between ECP levels and peripheral blood eosinophil numbers (rs = 0.67, P < 0.001).

Diagnostic reliability considerations of specific IgE determination

Total IgE determination constitutes a good method for the screening of atopic diseases, though its actual value is controversial because normal values of total IgE do not exclude the existence of atopic disease, and high values of total IgE are not pathognomonic of atopy by themselves. The first step in identifying an atopic individual as such, after doing his anamnesis, can be carried out by means of total IgE determination. Most atopic individuals have high IgE values, but a normal result must be carefully interpreted: age and season-related variations must be considered. In general, atopic patients with IgE values greater than 1000 Ul/ml, always have positive specific IgE against some allergen. Antigen-specific IgE will be the next step in the in vitro identification of the responsible allergen. Nowadays, there are more than 400 characterized allergens available for in vitro diagnostic tests and several useful methodologies for specific IgE determination. Specific IgE results obtained with the different methods vary significantly, with absolute agreement in 55-65% of the cases, differences in one IgE class in 20-30% of the cases and differences in more than two classes in 5-10%. The specificity of the anti-IgE antibody used in the assay is of critical importance because any contaminant antibody can render unspecific results. On the other hand, it must be pointed out that there is a compromise between specificity and sensitivity, such that an increase in the sensitivity of a technique leads to a decrease in its specificity. It cannot be said that there is one method which is better than the others; it is better to examine them individually, allergen by allergen. Thus, specific IgE determination varies depending on the type of allergen. In general terms, for inhalant allergens, specificity and sensitivity of the methods are within the range of 85-95%, but these values (especially the specificity) decrease in the case of food allergens, and they are still lower when the allergen is a beta-lactamic drug. There is a good correlation between clinical history and specific IgE against inhalant allergens, and a lower correlation in the case of food allergens. Due to the fact that most food allergens are not standardized, the definitive diagnosis of food hypersensitivity is achieved by means of provocation tests. Nevertheless, negative specific IgE (7-18% of the cases) does not rule out a sensitization against the tested allergen, and a positive specific IgE without symptoms must be carefully interpreted because it can be due to a low degree of sensitization, unable to express clinical symptoms at this moment, but useful in the future as a guide on the disease course. In the evolutive period of the disease, specific IgE levels can be modified in a natural way (in beta-lactam allergy, 50% of the cases with specific IgE become negative after a year), or as an effect of the treatment (e.g., after immunotherapy in the case of Hymenoptera venom allergy), or it can remain positive for a long time, as in the case of pollinosis. On the other hand, the cutoff of the method, and subsequently the range of values to be considered as positive, will depend on the allergen studied. While inhalant allergens (with the exception of some molds) offer relatively high mean values of specific IgE, food and drug allergens yield less significant values. In general, a class greater than 2 is interpreted as clinically significant, class 1 as dubious or negative (depending on the allergen) and class 0 as negative. In the interpretation of the results, the possible presence of IgG and anti-IgE antibodies, capable of modifying the results, will be taken into account. When comparing the diagnostic reliability of specific IgE with respect to other allergologic diagnostic methods, we find a significant and positive correlation of this technique with skin tests (but never greater than 90-95%) and with the histamine release test.

Specific IgE determination in the diagnosis of beta-lactam allergy

Allergic reactions to beta-lactams are the most frequent adverse reactions to drugs, but conventional methods of detection of beta-lactam specific IgE detect only a low number of positivities. In this study we evaluated the diagnostic reliability of one of these methods (CAP FEIA, Pharmacia) which has been proven very useful in inhalant and food specific IgE determinations. We studied specific IgE to penicillin G, penicillin V, amoxicillin and ampicillin in 1078 patients who had been diagnosed with an adverse reaction to beta-lactams, and out of this group, in a selected subgroup of 149 patients with a very suggestive clinical history of beta-lactam anaphylactic reaction. Also, positivity of specific IgE was studied in a group of 58 patients with a clinical history of immediate hypersensitivity to beta-lactams and with positive skin tests, and positivity of skin tests was studied in a subgroup of 13 patients with positive specific IgE. To increase the sensitivity of IgE determinations, we concentrated 5-fold the sera from six selected patients. In the first group we found that penicillin G specific IgE was positive in 28% of the cases when considering a cutoff > or = class 1, and 6% when considering a cutoff > or = class 2. For penicillin V, positivities were 9% (> or = class 1) and 4% (> or = class 2). In the second group, we found 31.81% sensitivity and 88.57% relative specificity of CAP FEIA with respect to the skin test. In the group of 58 patients with a clinical history of immediate hypersensitivity to beta-lactams, we found a disagreement between skin testing and specific IgE determination in 28.2%, and a positive agreement in 9.4% of the cases. After sera concentration, there was a significant increase (p < 0.001), from 0.58 to 1.61 kU/l, in beta-lactam specific IgE. Our results suggest that skin testing offers greater reliability and sensitivity than beta-lactam specific IgE determination by CAP FEIA.

Reliability of histamine release test in dust mite allergy: influence of the degree of sensitization

The histamine release test has been proven to be a very useful method for in vitro diagnosis of IgE-mediated allergy to inhalant and food allergens, as well as for the immunotherapy follow-up of the allergic patient. The aim of the present study was to assess the influence of the degree of sensitization in allergic patients sensitive to Dermatophagoides pteronyssinus on their dose-response curves in histamine release tests. To achieve this aim, we studied 109 D. pteronyssinus allergic patients and 25 healthy control subjects. Intracutaneous skin test, D. pteronyssinus-specific and total IgE quantitations, and histamine release tests were carried out in all the patients. In the case of the histamine release test, five D. pteronyssinus extract concentrations were used (2822.5, 282.25, 28.22, 2.82 and 0.28 UBE/ml), and two patterns of histamine release in sensitive patients were found: one with maximal histamine release at the highest antigen concentration (group I) and the other with maximal release attained at lower concentrations (group II). A sensitization score was designed, after the results from specific IgE and intracutaneous skin tests. There were significant differences (p < 0.05) in antigen-specific and total IgE levels, and in papule diameters and sensitization scores, between the control group and groups I and II. Both groups showed significantly higher (p < 0.05) histamine releases than the control group in response to anti-IgE antibodies. When stimulating the cells with anti-IgE antibodies, histamine release in group II was higher than in group I, although this difference was not significant. Finally, the best correlation between sensitization score and antigen-specific histamine release was found at the 2.82 UBE/ml concentration (r = 0.84, p < 0.001).

Prolonged half-life in the circulation of a chemical conjugate between a pro-urokinase derivative and human serum albumin

Pro-urokinase is a natural plasminogen activator that displays a clot-lysis activity through a fibrin-dependent mechanism. It seems to be a promising agent for the treatment of coronary thrombosis. Like tissue-type plasminogen activator and two-chain urokinase-type plasminogen activator, pro-urokinase has a very short half-life in circulation. It has been described that conjugation of serum albumin with pro-urokinase in plasma may occur that could protect this protein from degradation. In this study we describe the insertion of an extra cysteine residue in the N-terminal end of des-(C11-K135)-pro-urokinase (delta 125-proUK), a pro-urokinase deletion mutant lacking amino acids 11-135. We have expressed and purified the new mutein [H5K, S9C, N10T] des-(C11-K135)-pro-urokinase (Cys-delta 125-pro-urokinase) and chemically conjugated it with serum albumin via the extra cysteine of Cys-delta-pro-urokinase. The purified conjugate obtained has a lower specific amidolytic activity (72,000 U/mg) than unconjugated Cys-delta 125-pro-urikinase (240,000 U/mg) due to its higher molecular mass and has a similar fibrinolytic activity in a clot lysis test to that of delta 125-pro-urokinase. We established an ELISA to measure the concentration of the conjugate in plasma and to follow the pharmacokinetics of the conjugate in monkeys after bolus injection. The conjugate displays significant lysis of human plasma clots in vivo and a dramatic increase of the half-life in the circulation, with respect to pro-urokinase and delta 125-pro-urokinase. Therefore, preliminary biological characterisation of this conjugate indicates that it could be a good candidate to inject as a bolus, compared with the infusion regimen needed with pro-urokinase.

Simple strategy to induce antibodies of distinct specificity: application to the mapping of gp120 and inhibition of HIV-1 infectivity

In this study 96 15-mer peptides encompassing the entire sequence of HIV-1 gp120 were synthesized and used to immunize BALB/c mice (i) alone or (ii) in conjunction with the T helper cell determinant FISEAIIHVLHSR (FIS) from sperm whale myoglobin, which is well recognized by major histocompatibility complex (MHC) class II molecules of BALB/c. Of these peptides 39 were immunogenic per se and 57 were not. Out of the 57 non-immunogenic peptides 53 could be rendered immunogenic with the second immunization protocol. With the exception of 4 cases, the anti-peptide antibody titers induced in (ii) were equal (14 cases) or higher (78 cases) than those induced in (i). From the 96 anti-peptide antibodies tested, 12 were able to recognize recombinant gp120 with good antibody titers, a result in agreement with previously identified B cell epitopes from gp120 by anti-peptide antibodies induced with longer peptides conjugated to a carrier protein. Moreover, 4 of the 12 anti-peptide antisera that recognized gp120 were able to neutralize HIV-1 infectivity in vitro, showing that the strategy of co-immunization with FIS may afford functional antibodies.

Thallium-201-dipyridamole imaging: comparison between a standard dose and a high dose of dipyridamole in the detection of coronary artery disease

The purpose of this study was to compare two different doses of dipyridamole as a pharmacologic stress test for 201Tl imaging.

METHODS

Twenty-four patients with significant coronary artery disease (15 had undergone a coronary angiogram and 9 had undergone a previous 201Tl study with a significant lesion) were prospectively studied. Within 1 wk, all patients underwent two 201T-dipyridamole myocardial planar studies, one using a standard dose (STD) and the other, a high dose (HIGH) of dipyridamole. The protocol order was randomly assigned. The STD protocol used a dose of 0.14 mg/kg/min for a duration of 4 min (0.56 mg/kg), and the HIGH protocol used a dose of 0.14 mg/kg min for a duration of 6 min (0.84 mg/kg). The 201Tl was injected 3 min after the end of the dipyridamole infusion. Images, obtained 5 min and 4 hr later, were interpreted (divided into five segments each) by three blinded observers.

RESULTS

The STD protocol showed normal, ischemia and scar in 252, 91 and 17 segments, respectively. The HIGH protocol detected 232, 118 and 10 segments, respectively. A side-by-side evaluation was done to evaluate the defect extent subjectively, which was greater with HIGH in 14, equal in six and smaller in four patients. One or more side effects were seen in 14 patients with STD and in 19 with HIGH. Increased heart rate (8 bpm for STD and 19 bpm for HIGH, p < 0.001) was the only significant change seen in the hemodynamic parameters.

CONCLUSION

This preliminary study indicates that a high dose of dipyridamole seems to be safe and can be helpful to increase the sensitivity of 201Tl imaging.

Overcoming class II-linked non-responsiveness to hepatitis B vaccine

This work shows that class II-linked humoral lack of response to an antigen can be overcome by joint immunization with the antigen and a T-helper cell determinant (TDh) well recognized by class II molecules of a non-responder individual. Thus, SJL/J mice (H-2s), which are non-responders to the S region of hepatitis B virus surface antigen (HBsAg), were rendered responders by joint immunization with a recombinant surface antigen, only composed of the S region, and a short synthetic TDh peptide well recognized by the H-2s restriction. By contrast, when this peptide is not recognized as TDh, as in B10M mice (H-2f restricted and also non-responders to the S region), no humoral response could be induced against the S region. These results have important implications for therapy and vaccination against hepatitis B virus as well as in enhancing the immunogenicity of other antigens.