Inhibition of cyclobutane pyrimidine dimer formation in epidermal p53 gene of UV-irradiated mice by alpha-tocopherol

Mutations or alterations in the p53 gene have been observed in 50-100% of ultraviolet light (UV)-induced squamous cell carcinoma in humans and animals. Most of the mutations occurred at dipyrimidine sequences, suggesting that pyrimidine dimers in the p53 gene play a role in the pathogenesis of cutaneous squamous cell carcinoma. We previously showed that topical alpha-tocopherol prevents UV-induced skin carcinogenesis in the mouse. In the present study we asked whether topical alpha-tocopherol reduces the level of UV-induced cyclobutane pyrimidine dimers in the murine epidermal p53 gene. Mice received six dorsal applications of 25 mg each of alpha-tocopherol, on alternate days, before exposure to 500 J/m2 of UV-B irradiation. Mice were killed at selected times after irradiation. The level of dimers in the epidermal p53 gene was measured using the T4 endonuclease V assay with quantitative Southern hybridization. Topical alpha-tocopherol caused a 55% reduction in the formation of cyclobutane pyrimidine dimers in the epidermal p53 gene. The rate of reduction of pyrimidine dimers between 1 and 10 hours after irradiation was similar in UV-irradiated mice, regardless of alpha-tocopherol treatment. Therefore, the lower level of cyclobutane pyrimidine dimers in UV-irradiated mice treated with alpha-tocopherol than in control UV-irradiated mice resulted from the prevention of formation of the dimers, and not from enhanced repair of these lesions. Our results indicate that alpha-tocopherol acts as an effective sunscreen in vivo, preventing the formation of premutagenic DNA lesions in a gene known to be important in skin carcinogenesis.

VE-Cadherin mediates endothelial cell capillary tube formation in fibrin and collagen gels

Various cell adhesion molecules mediate the diverse functions of the vascular endothelium, such as cell adhesion, neutrophil migration, and angiogenesis. In order to identify cell adhesion molecules important for angiogenesis, we used an in vitro model (Chalupowicz, Chowdhury, Bach, Barsigian, and Martinez, J. Cell Biol. 130, 207-215, 1995) in which human umbilical vein endothelial cell monolayers are induced to form capillary-like tubes when a second gel, composed of either fibrin or collagen, is formed overlying the apical surface. In the present investigation, we observed that a monoclonal antibody directed against the first extracellular domain of human vascular endothelial cadherin (VE-cadherin, cadherin 5) inhibited the formation of capillary tubes formed between either fibrin or collagen gels. Moreover, when added to preformed capillary tubes, this antibody disrupted the capillary network. In contrast, monoclonal antibodies directed against the extracellular domain of N-cadherin, the alphavbeta3 integrin, and PECAM-1 failed to inhibit capillary tube formation. During capillary tube formation, Western blot and RT-PCR analysis revealed no marked change in VE-cadherin expression. Immunocytochemical studies demonstrated that VE-cadherin was concentrated at intercellular junctions in multicellular capillary tubes. Thus, VE-cadherin plays a specific role in fibrin-induced or collagen-induced capillary tube formation and is localized at areas of intercellular contact where it functions to maintain the tubular architecture. Moreover, its function at tubular intercellular junctions is distinct from that at intercellular junctions present in confluent monolayers, since only the former was inhibited by monoclonal antibodies.

Synthesis and biological activity of glutamic acid derivatives

In order to develop new specific glutamate analogues at metabotropic glutamate receptors, Diels-Alder, 1-4 ionic and radical reactions were performed starting from (2S)-4-methyleneglutamic acid. Preliminary pharmacological evaluation by measuring IP accumulation using rat forebrain synaptoneurosomes has shown that (2S)-4-(2-phthalimidoethyl)glutamic acid (3a), (2S)-4-(4-phthalimidobutyl)glutamic acid (3b) and 1-[(S)-2-amino-2-carboxyethyl]-3,4-dimethylcyclohex-3-ene-1-carbox ylic acid (8) presented moderate antagonist activities.

Cytokine responses in Trypanosoma cruzi-infected children in Paraguay

Both parasite and host immune factors may contribute to the development and progression of chronic chagasic cardiomyopathy during Trypanosoma cruzi infections. The present study targeted infected children (5-14 years of age) from an endemic area of Paraguay in an analysis of T. cruzi-specific cytokine profiles. This age group is characteristically the most affected by the early phases of infection. Trypanosoma cruzi-induced cytokine gene expression (interleukin-2 [IL-2], and interferon-gamma [IFN-gamma], IL-4, and IL-10) was studied in 25 seropositive children categorized as being either acute, symptomatic, with Romana's sign (n = 2), or early, indeterminate (postacute, n = 23). Acutely infected children showed a distinct T helper cell-1 (Th1)-type (IFN-gamma) cytokine response to infection. The cytokine pattern that was observed in the seropositive, asymptomatic (early, indeterminate) group was of the Th0 type (expression of both IFN-gamma and IL-4). We hypothesize that selective induction of a Th0-type cytokine pattern is important for development of cell-mediated and humoral immune responses that suppress parasite burden, thereby prolonging the onset or limiting the severity of chronic Chagas' disease later in life.

Comparative study of in vitro and in vivo activities of bombesin pseudopeptide analogs modified on the C-terminal dipeptide fragment

Analogs of bombesin in which the peptide bond between the two last amino acid residues were replaced by a pseudopeptide bond mimicking the transition state analog were evaluated. These compounds were able to recognize the bombesin receptor on isolated rat pancreatic acini with high potency (Ki from 0.60 +/- 0.27 nM to 4.3 +/- 2.3 nM). Although they were devoid of agonist activity, they were able to antagonize bombesin-induced amylase secretion in this model, with potencies in accordance with their affinities (IC50 from 1.6 +/- 0.3 nM to 10.0 +/- 1.7 nM). When tested in vivo in the anesthetized rat, these bombesin receptor antagonists exhibited high potency in inhibiting bombesin-induced pancreatic secretion (H-DPhe-Gln-Trp-Ala-Val-Gly-His-NH-CH[CH2-CH(CH3)2]-CHOH-(CH 2)3-CH3, JMV845, was among the most potent compounds with ED50 of 7.82 +/- 2.89 nM in inhibiting bombesin-induced protein secretion). The results of this study showed that replacing the peptide bond between the two last amino acid residues in bombesin by mimicking the transition state analog resulted in in vitro and in vivo potent bombesin receptor antagonists.

Biological activity and three-dimensional structure of an agonist analog of bombesin

JMV635, a nonapeptide analog of the active terminal nonapeptide segment of bombesin, was tested for its ability to stimulate in vitro amylase release from rat pancreatic acinar cells and to inhibit the binding of gastrin-releasing peptide to rat pancreatic acini. It was found to be a full agonist of bombesin and to recognize the bombesin receptor with moderate potency. The NMR proton assignments of JMV635 were achieved, and the conformations of JMV635 in aqueous solution and in trifluoroethanol at 297 K were determined using two-dimensional COSY, HOHAHA, NOESY and ROESY experiments. In trifluoroethanol, JMV635, like the active part of bombesin, showed a partial alpha-helical structure. These results were confirmed by circular dichroism and refined by restrained molecular dynamic methods. Structure calculations, using the distance and angle restraints obtained from NMR data on JMV635, gave a total of 75 structures which could be aligned to a root mean square deviation of the bond length of 0.007 A and of the valence angle of 1.55 degrees for the backbone atoms of the amino acid residues. The conformation is a well-defined right-handed alpha-helix in the C-terminal Q2-G6 segment and is less structured in the three C-terminal residues.

Melanin-concentrating hormone binding sites in human SVK14 keratinocytes

Melanin concentrating hormone (MCH) is a cyclic peptide which regulates a broad array of functions in the mammalian brain and it may act as a paracrine factor in peripheral organs. In these studies a radiolabeled MCH derivative, the [125I]-[Phe13, Tyr19]-MCH, was synthesized and used as a tracer to perform binding experiments. A number of human or rodent cell lines displayed specific binding with [125I]-[Phe13, Tyr19]-MCH, the highest binding capacity being observed with human SVK14 keratinocytes. Saturation binding analysis with SVK14 cells indicated about 10,000 MCH binding sites per cell and a Kd of 0.7 nM for [125I]-[Phe13, Tyr19]-MCH. Surprisingly, the iodinated [Phe13, Tyr19]-MCH displayed about 10-fold higher affinity (Ki approximately 3.0 nM) for the putative MCH receptor than the noniodinated form (Ki approximately 25-30 nM). Competition binding analyses comparing various MCH-related peptides revealed a similar low binding potency for all these peptides (Ki approximately 65-160 nM). Strikingly, rat ANP and rat/human CNP but not rat BNP displaced [125I]-[Phe13, Tyr15]-MCH with Ki approximately 210-365 nM and may be due to topological similarities instead of partial sequence identities between MCH and some of the natriuretic peptides. However, other peptides such as CRF, alpha MSH, Arg-vasopressin, and MGOP-peptide I did not compete with the radioligand. Finally, the molecular mass of the MCH binding sites on SVK14 cells was estimated to be 47 kDa by crosslinking and SDS-PAGE experiments. Taken together, our data revealed the widespread expression of MCH binding sites on mammalian cells, particularly on skin carcinoma cells. However, the low affinity of these sites for the native MCH and MCH-related peptides as well as competitivity with ANP and CNP indicates that further biochemical and functional characterizations are needed to validate them as genuine physiological MCH receptors.

A new biological contribution of cyclo(His-Pro) to the peripheral inhibition of pancreatic secretion

The tripeptide pyro-Glu-His-Pro-NH2[thyrotropin-releasing hormone (TRH)] was isolated from the hypothalamus as a thyrotropin-releasing factor. It has a broad spectrum of central nervous system-mediated actions, including the stimulation of exocrine pancreatic secretion. TRH is also synthesized in the endocrine pancreas and found in the systemic circulation. Enzymatic degradation of TRH in vivo produces other bioactive peptides such as cyclo(His-Pro). Because of the short half-life of TRH and the stability of cyclo(His-Pro) in vivo, we postulated that at least part of the peripheral TRH effects on the exocrine pancreatic secretion may be attributed to cyclo(His-Pro), which has been shown to have other biological activities. This study determines in parallel the peripheral effects of TRH and cyclo(His-Pro) as well as the putative contribution of other TRH-related peptides on exocrine pancreatic secretion in rats. TRH and its metabolite cyclo(His-Pro) dose dependently inhibited 2-deoxy-D-glucose (2-DG)-stimulated pancreatic secretion. TRH and all the related peptides tested had no effect on the basal and cholecystokinin-stimulated amylase release from pancreatic acinar cells in vitro. These data indicate that cyclo(His-Pro) mimics the peripheral inhibitory effect of TRH on 2-DG-stimulated exocrine pancreatic secretion. This effect is not detected on isolated pancreatic acini. Our findings provide a new biological contribution for cyclo(His-Pro) with potential experimental and clinical applications.

Social work at the emergency department

We have evaluated the level of satisfaction of patients assigned to a social worker whose role was to give information, support, advice, grief and shock counselling; and develop resource strategies for marginal peoples. Six hundred patients were admitted to the study; 300 of them were supervised by a social worker (group A) and the other 300 were not (group B). After the completion of the study, a questionnaire was sent to be filled in by group A and group B for later evaluation. We collected 200 completed questionnaires (33.3%). The most important areas were: 105 patients (94.5%) in group A vs. 73 patients (82%) (p < 0.005) consider the medical care good or very good. The waiting time was assessed as short or acceptable in 91 patients (81.9%) in group A vs. 55 patients (61.8%) in group B (p < 0.001). The psychosocial care was assessed as very good or good in 101 patients group A (90.9%) vs. 73 patients in group B (82%) (p < 0.5).

[Intraneural synovial cyst of the peroneal nerve. Case report]

The authors report the case of an intraneural synovial cyst of the peroneal nerve. The initial symptom was pain and weakness of dorsiflexion and eversion of the right foot. The patient was operated on and the cyst was totally resected. The authors discuss the pathogenesis, clinical diagnosis as well as the treatment of that uncommon lesion.

Effect of antipanic treatment on response to carbon dioxide

BACKGROUND

Disordered breathing among patients with panic disorder, including hyperventilation during attacks and increased anxiogenic response to carbon dioxide (CO2) inhalation, is well established. We wished to assess whether there is a change in the physiological response to CO2 after patients have undergone antipanic therapy with either tricyclic antidepressants or cognitive behavioral therapy (CBT).

METHODS

Twenty-nine patients with panic disorder underwent baseline CO2 sensitivity testing using the traditional Read rebreathing method and then received either antidepressant treatment (n = 21) or CBT (n = 8). After completing treatment, CO2 testing was repeated. A comparison sample of 14 normal volunteers also had two CO2 sensitivity tests, separated by an average of 21.6 (SD = 8.8) weeks.

RESULTS

Using a liberal standard, in which all CO2 sensitivity tests whose correlations between minute ventilation and end-tidal CO2 were at least .75 were used, patients, but not controls, demonstrated a significant reduction in CO2 sensitivity between the first and second test. Using a more conservative .90 correlation standard reduced the sample size available and resulted in trend reduction in patients but no significant change in controls. There was a suggestion that the change was most pronounced in treatment responders, although the number of patient nonresponders is extremely small in this sample.

CONCLUSIONS

These data indicate that treatment reduces CO2 sensitivity in patients with panic disorder. We speculate that manipulation of the serotonergic and noradrenergic neurotransmission systems, both known to play a role in the control of respiration, may have a specific effect in reducing respiratory hyperactivity in panic disorder.

Cloning and high level expression of Cynodon dactylon (Bermuda grass) pollen profilin (Cyn d 12) in Escherichia coli: purification and characterization of the allergen

BACKGROUND

Profilin, an actin-binding protein, was previously described as a panallergen which is involved in about 20% of the crossreactivity found among pollen and food allergic patients. This allergen is usually under-represented in natural extracts used for allergy diagnosis.

OBJECTIVES

To obtain an immunologically active and soluble recombinant profilin from Cynodon dactylon pollen which could be used for diagnostic and therapy.

METHODS

Isolation of cDNA clones was performed by polymerase chain reaction amplification using degenerate primers. Expression in Escherichia coli BL21 (DE3) was carried out using vector pKN172, and the expressed product was isolated by affinity chromatography on poly L-proline-Sepharose.

RESULTS

Four cDNA inserts coding for Cynodon dactylon (Bermuda grass) pollen profilin (Cyn d 12) were cloned and sequenced. Full-length C. dactylon profilin gene was expressed in Escherichia coli as non fusion protein. Induced cells could produce high amounts of recombinant Cyn d 12, and after a single purification step on poly (L-proline)-Sepharose, up to 45 mg of pure allergen per litre culture could be obtained. The reactivity of recombinant Cyn d 12 with IgE antibodies present in sera from Bermuda grass-allergic patients is comparable to that of the natural Bermuda grass allergen. Recombinant Bermuda grass pollen profilin was shown to share B-epitopes with sunflower profilin.

CONCLUSIONS

Our results showed that this heterologous expression system and purification procedure are suitable for the production of large amounts of pure allergen which can be used for the characterization of allergenic epitopes recognized by T and B cells and finally for diagnostic and therapeutic purposes.

Role of prostaglandin H synthase-2-mediated conversion of arachidonic acid in controlling 3T6 fibroblast growth

The specific role(s) of arachidonic acid (AA) and its metabolites in the signaling pathways that regulated fibroblast growth was studied. A Western blot analysis demonstrated that prostaglandin H synthase-2 (PGHS-2) was expressed by 3T6 fibroblast cultures in RPMI 1640 supplemented with fetal calf serum (10%). Dexamethasone, which inhibits AA release and PGHS-2 expression, significantly reduced cell proliferation. Ketoprofen, a dual cyclooxygenase inhibitor, and CGP-28238, a specific PGHS-2 inhibitor, reduced fibroblast proliferation in a dose-dependent manner. These drugs also reduced [3H]thymidine incorporation into the DNA of fibroblasts. These effects were correlated with a decrease in prostaglandin (PG) E2 levels in the cell medium. However, piroxicam at doses that selectively inhibit PGHS-1 did not have a significant effect on fibroblast proliferation. Finally, we showed that the antiproliferative effect of dexamethasone and PGHS-2 inhibitors was significantly antagonized when PGE2 was added to the culture medium. Our results suggest that PGHS-2 and prostaglandins such as PGE2 might play an important role in the regulation of 3T6 fibroblast growth stimulated by growth factors of serum.

Effect of glicentin, oxyntomodulin and related peptides on isolated gastric smooth muscle cells

Glicentin (proglucagon 1-69 GLIC) and oxyntomodulin (proglucagon 33-69 or OXM) are two peptide hormones that are co-released from ileum and large intestine during digestion. They modulate in vivo gastric acid secretion and the gastro-pyloro-duodenal activity. The specificity of their effects is linked to the presence of their C-terminal octapepide. As yet, no isolated target cell that responds specifically to this family of peptides has been described. The present report describes the in vitro effect of human synthetic GLIC, OXM and octapeptide-bearing fragments on smooth muscle cells isolated from the rabbit antrum. GLIC or OXM decreased the mean length of the cells by: 13.9 +/- 0.8% and 15.5 +/- 0.9%, respectively - GLIC being 16 times more potent than OXM (respective EC50 values: 5 and 83 pM). The C-terminal fragments OXM(19-37) and OXM(30-37) were as efficient as GLIC or OXM. Their potencies were OXM = OXM(19-37)>>OXM(30-37). Glucagon, which corresponds to OXM without the C-terminal octapeptide, or glucagon-like peptide-1 (7-36 amide) did not have any effect. The response to OXM was not influenced by antagonists to muscarinic, cholecystokinin or substance P receptors. In conclusion, our studies demonstrate for the first time an isolated target cell that responds specifically to GLIC, OXM and other octapeptide-bearing peptides.

Characterization of new polyclonal antibodies specific for 40 and 42 amino acid-long amyloid beta peptides: their use to examine the cell biology of presenilins and the immunohistochemistry of sporadic Alzheimer's disease and cerebral amyloid angiopathy cases

BACKGROUND

In Alzheimer's disease (AD), the main histological lesion is a proteinaceous deposit, the senile plaque, which is mainly composed of a peptide called A beta. The aggregation process is thought to occur through enhanced concentration of A beta 40 or increased production of the more readily aggregating 42 amino acid-long A beta 42 species.

MATERIALS AND METHODS

Specificity of the antibodies was assessed by dot blot, Western blot, ELISA, and immunoprecipitation procedures on synthetic and endogenous A beta produced by secreted HK293 cells. A beta and p3 production by wild-type and mutated presenilin 1-expressing cells transiently transfected with beta APP751 was monitored after metabolic labeling and immunoprecipitation procedures. Immunohistochemical analysis was performed on brains of sporadic and typical cerebrovascular amyloid angiopathy (CAA) cases.

RESULTS

Dot and Western blot analyses indicate that IgG-purified fractions of antisera recognize native and denaturated A beta s. FCA3340 and FCA 3542 display full specificity for A beta 40 and A beta 42, respectively. Antibodies immunoprecipitate their respective synthetic A beta species but also A beta s and their related p3 counterparts endogenously secreted by transfected human kidney 293 cells. This allowed us to show that mutations on presenilin 1 triggered similar increased ratios of A beta 42 and its p 342 counterpart over total A beta and p3. ELISA assays allow detection of about 25-50 pg/ml of A beta s and remain linear up to 750 to 1500 pg/ml without any cross-reactivity. FCA18 and FCA3542 label diffuse and mature plaques of a sporadic AD case whereas FCA3340 only reveals the mature lesions and particularly labels their central dense core. In a CAA case, FCA18 and FCA3340 reveal leptomeningeal and cortical arterioles whereas FCA3542 only faintly labels such structures.

CONCLUSIONS

Polyclonal antibodies exclusively recognizing A beta 40 (FCA 3340) or A beta 42 (FCA3542) were obtained. These demonstrated that FAD-linked presenilins similarly affect both p342 and A beta 42, suggesting that these mutations misroute the beta APP to a compartment where gamma-secretase, but not alpha-secretase, cleavages are modified. Overall, these antibodies should prove useful for fundamental and diagnostic approaches, as suggested by their usefulness for biochemical, cell biological, and immunohistochemical techniques.

Differential targeting of nicotinic acetylcholine receptors by novel alphaA-conotoxins

We describe the isolation and characterization of two peptide toxins from Conus ermineus venom targeted to nicotinic acetylcholine receptors (nAChRs). The peptide structures have been confirmed by mass spectrometry and chemical synthesis. In contrast to the 12-18 residue, 4 Cys-containing alpha-conotoxins, the new toxins have 30 residues and 6 Cys residues. The toxins, named alphaA-conotoxins EIVA and EIVB, block both Torpedo and mouse alpha1-containing muscle subtype nAChRs expressed in Xenopus oocytes at low nanomolar concentrations. In contrast to alpha-bungarotoxin, alphaA-EIVA is inactive at alpha7-containing nAChRs even at micromolar concentrations. In this regard, alphaA-EIVA is similar to the previously described alpha-conotoxins (e.g. alpha-MI and alpha-GI) which also selectively target alpha1- versus alpha7-containing nAChRs. However, alpha-MI and alpha-GI discriminate between the alpha/delta versus alpha/gamma subunit interfaces of the mouse muscle nAChR with 10,000-fold selectivity. In contrast, alphaA-conotoxin EIVA blocks both the alpha/gamma site and alpha/delta site with equally high affinity but with distinct kinetics. The alphaA-conotoxins thus represent novel probes for the alpha/gamma as well as the alpha/delta binding sites of the nAChR.

Congenital dysfibrinogenemia

Fibrinogen abnormalities can be classified as congenital or acquired. Each class manifests quantitative or qualitative alterations; the latter are known as dysfibrinogenemias. In dysfibrinogenemias, structural defects cause alterations in the conversion of fibrinogen to fibrin. Approximately 300 abnormal fibrinogens have been reported, and about 83 structural defects have been identified. The most common structural defect involve the fibrinopeptides and their cleavage sites, and the second most common involves the gamma-chain polymerization region. Approximately half of the mutants are clinically silent, whereas hemorrhage and thrombosis occur in almost equal numbers of cases. Study of the abnormal fibrinogens has provided insight into fibrinogen structure and fibrin formation and dissolution. Some of the structural abnormalities exhibit defective assembly and activation of components of the fibrinolytic system on the abnormal fibrin, resulting in impaired dissolution of fibrin, clinically associated with thrombosis.

CholecystokininB receptor from human Jurkat lymphoblastic T cells is involved in activator protein-1-responsive gene activation

The aim of this study was to analyze the role of cholecystokinin (CCK(B)) receptor in human lymphoblastic Jurkat T cells. We investigated the trophic effect resulting from activation of such a receptor by using the reporter gene strategy. For this purpose, we transiently transfected Jurkat T cells with the reporter plasmid p[(TRE)3-tk-Luc] and found that CCK-8 was able to dose-dependently induce luciferase expression related to activator protein-1 (AP-1) activation with a maximal response identical to that obtained with compounds known to activate AP-1 complex (quantitatively, the same level of induction was obtained with 1 nM 12-O-tetradecanoylphorbol-13-acetate, 100 microM diacylglycerol, or 4 nM epidermal growth factor). The involvement of the CCK(B) receptor in such a stimulation was demonstrated by the inhibiting effect of the selective CCK(B) receptor antagonist PD-135,158. This effect was confirmed in COS-7 cells transfected with the cDNA of CCK(B) receptor cloned from Jurkat T cells. To better understand the AP-1-dependent luciferase expression in Jurkat T cells, we tested two specific inhibitors of serine/threonine phosphatases-1 and -2A: okadaic acid and calyculin A. These compounds strongly increased the phorbol-12-myristate-13-acetate response, whereas we have not observed a contribution of phosphatase inhibitors on a CCK-8-induced luciferase activity. To confirm that CCK(B) receptors are involved in AP-1 response, we investigated the CCK-8 effect on interleukin-2 expression, a natural endogenous gene regulated by several factors, including AP-1. In Jurkat T cells activated by phorbol-12-myristate-13-acetate and phytohemagglutinin, CCK-8 induced IL-2 expression. This induction was abolished by PD-135,158. Our results indicate that CCK-8 exerts a trophic effect in Jurkat T cells through stimulation of CCK(B) receptors by modulation of expression of AP-1-regulated genes.