305 FIRST REPORT OF THE USE OF SEXED SEMEN BY FLOW CYTOMETRY IN BOS INDICUS

The only method of sexing sperm that works in any practical sense is measuring DNA content of individual sperm by flow cytometry, and sorting them based on that information (Schenk and Seidel 2002 J. Anim. Sci. 80 (Suppl. 1), 188). This is, also, the first reference of the use of sexed semen in Brazil. The objective of this experiment was to compare the fertility of sexed and non-sexed conventional semen in Bos indicus purebreeds. Ejaculates from eight Nelore bulls were collected by artificial vagina, diluted, and stained with Hoeschst 33342 (Schenk et al. 1999 Theriogenology 52, 1375–1391). A high-speed flow cytometer (SX-MOFLO®, DakoCytomation, Inc., Fort Collins, CO, USA) was used for sorting X sperm. Sexed semen was then packaged at 3 million total sperm in 0.25-mL straws and frozen. The average estimated purity obtained by resort analysis of one straw per batch was 91.5%. An aliquot of each ejaculate was frozen unsexed at a concentration of 50 × 106 sperm/mL in 0.5-mL straws (control). A total of 283 Nelore heifers were synchronized with two doses of PGF2α 12 days apart and inseminated in the body of the uterus 12 h after heat detection. Field trials were carried out in four different states in Brazil: Minas Gerais (MG), Mato Grosso (MT), Mato grosso do Sul (MS), Rondônia (RO). Pregnancy diagnosis and fetal sex determination were performed by ultrasound 30 and 60 days post-AI, respectively. Data were analyzed by chi-square and Monte Carlo methods. There was no significant difference (P < 0.05) in pregnancy rate between sexed and non-sexed semen (see Table 1). At the time of abstract submission, of 41 pregnant heifers from sexed semen confirmed by ultrasound, 40 had a female fetus (97%). These results indicate that sexing semen by flow cytometry could be a very important tool to accelerate the genetic gain in Bos indicus cattle. Brazil has the largest commercial herd in the world and, therefore, a great potential to incorporate this technology that is now available in the country. Table 1.

Striatal plasticity at the network level. Focus on adenosine A2A and D2 interactions in models of Parkinson's Disease

Behavioral and microdialysis studies have been performed on antagonistic A(2A)/D(2) interactions in animal models of Parkinson's Disease. The behavioral analysis involved studies on locomotor activity in reserpinized mice, haloperidol-induced catalepsy in rats and rotational behavior in rats with unilateral 6-OHDA lesions of the ascending DA pathways (Ungerstedt model). Dual probe microdialysis studies were indirectly performed on the striatopallidal GABA neurons by studying extracellular glutamate levels in the striatum and globus pallidus of the awake freely moving rat. The striatum was perfused with A(2A) and/or D(2) agonists via reverse microdialysis. The results show that the A(2A) antagonists SCH58261 and KF17837 can increase locomotor activity in reserpinized mice and produce contralateral rotational behavior only after administration of subthreshold doses of l-DOPA or the D(2) like agonist quinpirole. Furthermore, antagonizing the A(2A) receptor (R) reduced haloperidol induced catalepsy. The behavioral results underline the view that A(2A) antagonists act by blocking A(2A) R in A(2A)/D(2) heterodimers where A(2A) R inhibits the D(2) R transduction and D(2) inhibits the adenylate cyclase (AC) activated by A(2A) R. The microdialysis studies show that the A(2A) agonist CGS21680 striatally coperfused with the D(2) agonist quinpirole more potently counteract the D(2) agonist (quinpirole) induced reduction of pallidal glutamate levels in the DA denervated vs the control striatum indicating an enhancement of the inhibitory A(2A)/D(2) interaction. In the DA denervated but not in the control striatum the A(2A) agonist CGS21680 could strongly increase striatal glutamate levels, indicating an increased receptor signaling in the A(2A) R located on the striatal glutamate terminals, where also D(2) like R exist, here probably as D(4). Thus, the signaling of this A(2A) R may be set free by the loss of D(4) tone on the AC activated by A(2A) in this postulated A(2A)/D(4) heteromer on the glutamate terminals. Taken together, the results indicate that the antiparkinsonian actions of A(2A) antagonists probably are produced by blockade of A(2A) R in the A(2A)/D(2) heterodimers mainly located in the striatopallidal GABA neurons.

Studies on homocysteine plasma levels in Alzheimer?s patients. Relevance for neurodegeneration

Homocysteine (HC) may work inter alia as a Volume Transmission signal since HC is present in the brain and cerebrospinal fluid and binds to NMDA receptors. Furthermore, in cell cultures increased HC formation increases its export. In the present study we have shown that after intravenous injection in intact animals HC penetrates the blood-brain barrier. Hence, it works as a blood-born humoral signal. Furthermore, we have studied HC plasma levels in a group of Alzheimer's (AD) patients and compared with a group of age-matched patients. It has been confirmed that a positive correlation exists between age and HC plasma levels in the control group, but not in the AD patients. These results may depend on the fact that in AD patients high HC plasma levels (possibly associated with high glycine levels and/or excessive glutamate release) have favored neurodegeneration and, once this pathological process has been triggered off, the plasma HC levels become independent of the "physiological" aging-induced increase of HC plasma levels.

Receptor heteromerization in adenosine A2A receptor signaling: relevance for striatal function and Parkinson's disease

Recently evidence has been presented that adenosine A2A and dopamine D2 receptors form functional heteromeric receptor complexes as demonstrated in human neuroblastoma cells and mouse fibroblast Ltk- cells. These A2A/D2 heteromeric receptor complexes undergo coaggregation, cointernalization, and codesensitization on D2 or A2A receptor agonist treatments and especially after combined agonist treatment. It is hypothesized that the A2A/D2 receptor heteromer represents the molecular basis for the antagonistic A2A/D2 receptor interactions demonstrated at the biochemical and behavioral levels. Functional heteromeric complexes between A2A and metabotropic glutamate 5 receptors (mGluR5) have also recently been demonstrated in HEK-293 cells and rat striatal membrane preparations. The A2A/mGluR5 receptor heteromer may account for the synergism found after combined agonist treatments demonstrated in different in vitro and in vivo models. D2, A2A, and mGluR5 receptors are found together in the dendritic spines of the striatopallidal GABA neurons. Therefore, possible D2/A2A/mGluR5 multimeric receptor complexes and the receptor interactions within them may have a major role in controlling the dorsal and ventral striatopallidal GABA neurons involved in Parkinson's disease and in schizophrenia and drug addiction, respectively.

Volume changes and whole cell membrane currents activated during gradual osmolarity decrease in C6 glioma cells: contribution of two types of K+ channels

Volume changes and whole cell ionic currents activated by gradual osmolarity reductions (GOR) of 1.8 mosM/min were characterized in C6 glioma cells. Cells swell less in GOR than after sudden osmolarity reductions (SOR), the extent of swelling being partly Ca(2+) dependent. In nominally Ca(2+)-free conditions, GOR activated predominantly whole cell outward currents. Cells depolarized from the initial -79 mV to a steady state of -54 mV reached at 18% osmolarity reduction [hyposmolarity of -18% (H-18%)]. Recordings of Cl(-) and K(+) currents showed activation at H-3% of an outwardly rectifying Cl(-) current, with conductance of 1.6 nS, sensitive to niflumic acid and 5-nitro-2-(3-phenylpropylamino)benzoic acid, followed at H-18% by an outwardly rectifying K(+) current with conductance of 4.1 nS, inhibited by clofilium but insensitive to the typical K(+) channel blockers. With 200 nM Ca(2+) in the patch pipette, whole cell currents activated at H-3% and at H-13% cells depolarized from -77 to -63 mV. A K(+) current activated at H-1%, showing a rapid increase in conductance, suppressed by charybdotoxin and insensitive to clofilium. These results show the operation of two different K(+) channels in response to GOR in the same cell type, activated by Ca(2+) and osmolarity and with different osmolarity activation thresholds. Taurine and glutamate efflux, monitored by labeled tracers, showed delayed osmolarity thresholds of H-39 and H-33%, respectively. This observation clearly separates the Cl(-) and amino acid osmosensitive pathways. The delayed amino acid efflux may contribute to counteract swelling at more stringent osmolarity reductions.

Energy gradients for VT-signal migration in the CNS: studies on melanocortin receptors, mitochondrial uncoupling proteins and food intake

The present paper enlightens a new point of view on brain homeostasis and communication, namely how the brain takes advantage of different chemical-physical phenomena such as pressure waves, and temperature and concentration gradients to allow the homeostasis of the brain internal milieu as well as some forms of intercellular communications (volume transmission, VT) at an energy cost much lower than the classical synaptic transmission (the prototype of wiring transmission, WT). The possible melanocortin control of uncoupling protein 2 (UCP2) expression (hence of local brain temperature gradients) has been studied in relation to food intake in male Wistar rats. Osmotic minipumps were subcutaneously (sc) implanted in the midscapular region for intracerebroventricular (icv) infusion. The control rats received an icv infusion of 0.5 microl/h of artificial cerebrospinal fluid (ACSF), while experimental rats received either an icv infusion of 0.16 nmol/h of HS024 or of 0.16 nmol/h of adrenocorticotropin-(1-24) [ACTH-(1-24)]. The ACTH-treated group ate significantly less than the ACSF-treated group during the first three days of infusion, while, subsequently, food intake of the two groups was similar. On the other hand, the HS024-treated group ate significantly more (up to 153% of the control value) than ACSF- and ACTH-treated rats during the entire period. UCP2 mRNA analysis in arcuate nuclei of ACTH, HS024 and ACSF-treated animals showed a significant 75% decrease (p<0.05 vs saline) of the total specific mRNA level in the HS024-treated group vs ACSF-treated animals (control group), while no significant change was observed between ACTH- and ACSF-treated animals. Melanocortin antagonist HS024 via blockade of MCR4 increases food intake and via a reduction of UCP2 expression enhances the food consumption ratio. This result underlines the fact that UCP2 expression and food intake can be differentially regulated. In other words, via a peptidergic control the central nervous system (CNS) can modulate the energy stored from the amount of the food that the animal has eaten and also uncouple the thermal micro-gradients (dependent on UCP2 expression) and hence the VT-signal micro-migrations from the food intake. It should also be noticed that the control of the thermal gradients affects also the neuronal firing rate and hence the transmitter release (likely above all the release of peptides such as neuropeptide Y (NPY), melanin-concentrating hormone (MCH) and beta-endorphin, e.g., in the arcuate nucleus representing signals relevant to energy homeostasis). Thus, WT and VT are both modulated by peptidergic signals that affect thermal gradients.

Dipropylcyclopentylxanthine triggers apoptosis in cells from patients with myeloid leukaemia

1,3-Dipropyl-8-cyclopentylxanthine (DPCPX), a xanthine analogue used as a selective antagonist of adenosine receptors, caused apoptosis in a variety of leukaemia-derived cell lines as well as in cells from patients with myeloid leukaemia. Apoptosis was assessed by flow cytometry, by DNA fragmentation and by accumulation of histones, H2A, H2B, R3 and H4, in the nucleoplasm of cells. Cell cycle analysis indicated that apoptosis occurred irrespective of the cell cycle phase. DPCPX did not trigger apoptosis in resting human peripheral blood lymphocytes; neither did it potentiate the apoptotic effect of phytohemagglutinin (PHA), when these cells were activated by PHA. These results indicate that DPCPX may be useful in the therapy of proliferative disorders of the hematopoietic system.

Possible role of intramembrane receptor-receptor interactions in memory and learning via formation of long-lived heteromeric complexes: focus on motor learning in the basal ganglia

Learning in neuronal networks occurs by instructions to the neurons to change their synaptic weights (i.e., efficacies). According to the present model a molecular mechanism that can contribute to change synaptic weights may be represented by multiple interactions between membrane receptors forming aggregates (receptor mosaics) via oligomerization at both pre- and post-synaptic level. These assemblies of receptors together with inter alia single receptors, adapter proteins, G-proteins and ion channels form the membrane bound part of a complex three-dimensional (3D) molecular circuit, the cytoplasmic part of which consists especially of protein kinases, protein phosphatases and phosphoproteins. It is suggested that this molecular circuit has the capability to learn and store information. Thus, engram formation will depend on the resetting of 3D molecular circuits via the formation of new receptor mosaics capable of addressing the transduction of the chemical messages impinging on the cell membrane to certain sets of G-proteins. Short-term memory occurs by a transient stabilization of the receptor mosaics producing the appropriate change in the synaptic weight. Engram consolidation (long-term memory) may involve intracellular signals that translocate to the nucleus to cause the activation of immediate early genes and subsequent formation of postulated adapter proteins which stabilize the receptor mosaics with the formation of long-lived heteromeric receptor complexes. The receptor mosaic hypothesis of the engram formation has been formulated in agreement with the Hebbian rule and gives a novel molecular basis for it by postulating that the pre-synaptic activity change in transmitter and modulator release reorganizes the receptor mosaics at post-synaptic level and subsequently at pre-synaptic level with the formation of novel 3D molecular circuits leading to a different integration of chemical signals impinging on pre- and post-synaptic membranes hence leading to a new value of the synaptic weight. Engram retrieval is brought about by the scanning of the target networks by the highly divergent arousal systems. Hence, a continuous reverberating process occurs both at the level of the neural networks as well as at the level of the 3D molecular circuits within each neuron of the network until the appropriate tuning of the synaptic weights is obtained and, subsequently, the reappearance of the engram occurs. Learning and memory in the basal ganglia is discussed in the frame of the present hypothesis. It is proposed that formation of long-term memories (consolidated receptor mosaics) in the plasma membranes of the striosomal GABA neurons may play a major role in the motivational learning of motor skills of relevance for survival. In conclusion, long-lived heteromeric receptor complexes of high order may be crucial for learning, memory and retrieval processes, where extensive reciprocal feedback loops give rise to coherent synchronized neural activity (binding) essential for a sophisticated information handling by the central nervous system.

Dipropylcyclopentylxanthine triggers apoptosis in Jurkat T cells by a receptor-independent mechanism

1,3-Dipropyl-8-cyclopentylxanthine (DPCPX), a xanthine analog used as selective antagonist of adenosine receptors, caused apoptosis in a human leukemia T cell line. Jurkat cells treated with DPCPX underwent apoptosis as demonstrated by flow cytometry, by DNA fragmentation and by accumulation of histones, H2A, H2B, H3 and H4, in the nucleoplasm of cells. Cell cycle and cell sorting analyses indicated an arrest of cells in G(2)/M followed by the appearance of apoptotic cells in G(1) and G(2)/M phases. The mechanism of programmed cell death does not seem to be mediated by signal transduction events at the plasma membrane since it did not involve activation of cell membrane receptors and modification of the intracellular levels of Ca(2+) or cAMP. Apoptosis by incorporation into DNA of a derivative of DPCPX is suggested in basis of the presence of radioactivity label in the DNA obtained from cells preincubated with [(3)H]DPCPX.

Loss of oestrogen receptor beta, high PCNA and p53 expression and aneuploidy as markers of worse prognosis in ovarian granulosa cell tumours

AIMS

Ovarian granulosa cell tumour (OGCT) is a sex-cord stromal tumour with a general trend toward late relapse and/or metastasis. However, mortality rate corrected for long-term follow-up shows that about 50% of patients die within 20 years of diagnosis. Classical clinicopathological parameters are unable to predict the biological behaviour of OGCT. The involvement of a recently characterized subtype of oestrogen receptor, ERbeta, in ovarian carcinogenesis has been hypothesized.

METHODS AND RESULTS

We examined by immunohistochemistry the expression of ERbeta, proliferating cell nuclear antigen (PCNA) and p53 in a selected series of 30 OGCT, to evaluate their role in the prognostic evaluation of this tumour. Immunohistochemistry was performed on formalin-fixed paraffin-embedded sections. Results were compared with the DNA-ploidy of the tumours (evaluated by image analysis) and with the follow-up data of the patients.

CONCLUSIONS

Loss of ERbeta expression, high PCNA expression and aneuploidy, characterized a subgroup of OGCT with a worse outcome. The identification of a high-risk subclass of OGCT may be of primary importance in addressing appropriate therapeutic strategies, offering the chance to prevent relapses and metastases by using adjunctive, specifically targetted, more aggressive therapies.

Interactions among adenosine deaminase, adenosine A(1) receptors and dopamine D(1) receptors in stably cotransfected fibroblast cells and neurons

The role of adenosine deaminase in the interactions between adenosine A(1) and dopamine D(1) receptors was studied in a mouse fibroblast cell line stably cotransfected with human D(1) receptor and A(1) receptor cDNAs (A(1)D(1) cells). Confocal laser microscopy analysis showed a high degree of adenosine deaminase immunoreactivity on the membrane of the A(1)D(1) cells but not of the D(1) cells (only cotransfected with human D(1) receptor cDNAs). In double immunolabelling experiments in A(1)D(1) cells and cortical neurons a marked overlap in the distribution of the A(1) receptor and adenosine deaminase immunoreactivities and of the D(1) receptor and adenosine deaminase immunoreactivities was found. Quantitative analysis of A(1)D(1) cells showed that adenosine deaminase immunoreactivity to a large extent colocalizes with A(1) and D(1) receptor immunoreactivity, respectively. The A(1) receptor agonist caused in A(1)D(1) cells and in cortical neurons coaggregation of A(1) receptors and adenosine deaminase, and of D(1) receptors and adenosine deaminase. The A(1) receptor agonist-induced aggregation was blocked by R-deoxycoformycin, an irreversible adenosine deaminase inhibitor. The competitive binding experiments with the D(1) receptor antagonist [(3)H]SCH-23390 showed that the D(1) receptors had a better fit for two binding sites for dopamine, and treatment with the A(1) receptor agonist produced a disappearance of the high-affinity site for dopamine at the D(1) receptor. R-Deoxycoformycin treatment, which has previously been shown to block the interaction between adenosine deaminase and A(1) receptors, and which is crucial for the high-affinity state of the A(1) receptor, also blocked the A(1) receptor agonist-induced loss of high-affinity D(1) receptor binding. The conclusion of the present studies is that the high-affinity state of the A(1) receptor is essential for the A(1) receptor-mediated antagonistic modulation of D(1) receptors and for the A(1) receptor-induced coaggregates of A(1) and adenosine deaminase, and of D(1) and adenosine deaminase. Thus, the confocal experiments indicate that both A(1) and D(1) receptors form agonist-regulated clusters with adenosine deaminase, where the presence of a structurally intact adenosine deaminase bound to A(1) receptors is important for the A(1)-D(1) receptor-receptor interaction at the level of the D(1) receptor recognition.

Synchronous primary adenocarcinoma and adenosquamous carcinoma of the esophagus

Multiple malignant esophageal tumors of the same cell type are described. In the esophageal mucosa, widespread carcinomatous transformation may be observed and multicentric invasive squamous cell carcinomas may develop. The concomitance of two independent esophageal malignant neoplasms of different epithelial histogenesis is uncommon. Synchronous adenocarcinoma and squamous cell carcinoma of the esophagus is reported. Adenosquamous carcinoma of the esophagus is a rare tumor. Adenocarcinoma of the esophagus represents 10% of esophageal cancer. We report a case of a synchronous primary invasive adenosquamous carcinoma and adenocarcinoma of the esophagus. Both tumors were demonstrated radiographically. The peculiarity of this neoplastic association and the importance of complete radiographic esophageal evaluation in patients with one obvious obstructing tumor of the esophagus are emphasized.

Cytokines regulate membrane adenosine deaminase on human activated lymphocytes

CD26 is a lymphocyte marker that can anchor adenosine deaminase (ADA) on the T cell surface. We found that ADA is regulated by cytokines on the cell surface during T cell activation. By means of flow cytometry, immunofluorescence, and immunoblotting techniques, we found that interleukin (IL)-2 and IL-12 up-regulate ecto-ADA and CD26 expression. In clear contrast, IL-4 led to down-regulation of lymphocyte surface ADA without modifying the level of CD26. Moreover, neither circulating ADA transcription nor mRNA translation was regulated by cytokines. These results, along with absence of total-ADA modulation, the variable amount of ADA found in purified plasma membranes, and the different effect of Brefeldin A on the surface presence of ADA and CD26 indicated that cytokines regulate the translocation of ADA towards the cell surface through a mechanism not involving CD26. Ecto-ADA protected activated lymphocytes from the toxic effects of extracellular adenosine. Therefore, this cell surface ADA control might constitute part of the fine immunoregulatory mechanism of adenosine-mediated signaling through purinergic receptors in leukocytes.

Medullary thyroid cancer, papillary thyroid microcarcinoma and Graves' disease: an unusual clinical coexistence

We describe the unusual case of a Caucasian woman who had a diagnosis of medullary thyroid cancer and papillary microcarcinoma 5 years after a diagnosis of Graves' disease. The patient came to our observation for recurrence of hyperthyroidism. An ultrasound scan revealed diffuse thyroid enlargement with a nodule, recently increased in size. The serum CT and carcinoembrional antigen were elevated, and the fine-needle aspiration cytology with immunocytochemical analysis for CT was suggestive for medullary thyroid carcinoma. The nodular lesion showed intense 111In-pentetreotide uptake, whereas total body scintigraphy with the same tracer and with Thallium-201, 99mTc (V) dimercaptosuccinic acid was negative for lymph node and distant metastasis. The histological examination of thyroidectomy specimens confirmed the diagnosis of medullary thyroid cancer, showing a lymphocytic intratumoral infiltration. The histological analysis of the controlateral lobe showed an occult papillary microcarcinoma. Medullary thyroid carcinoma and papillary microcarcinoma showed intense staining with policlonal anti-RET antibodies, although genetic analysis was negative for RET mutations most frequently involved in familial and sporadic medullary thyroid carcinomas. Possible implications about the coexistence of the 3 thyroid diseases are discussed.

Expression of PCNA in the testis of the lizard, Podarcis s. sicula: an endogenous molecular marker of mitotic germinal epithelium proliferation

Proliferating cell nuclear antigen (PCNA) plays an essential role in nucleic acid metabolism as a component of the replication and repair machinery. This protein encircles DNA and can slide bidirectionally along the duplex binding to DNA polymerase delta and epsilon. It is well known that PCNA interacts with proteins involved in the cell cycle. The PCNA interactions with different cellular proteins and the importance of these interactions are discussed. To examine mitotic germinal epithelium proliferation during annual discontinuous spermatogenesis in the lizard Podarcis s. sicula, temporal and the spatial PCNA expression were investigated, and provide a useful endogenous molecular marker.

Valsartan alone and as part of combination therapy in general practice in Brazil

The objective of this study was to assess the efficacy and tolerability of valsartan (Diovan) when given alone or as part of a combination regimen in normal clinical practice, in general practice patients in Brazil. In an open, multicentre post-marketing surveillance (PMS) study, 7256 hypertensive patients were evaluated. Therapy with valsartan either as monotherapy or in combination with 12.5 mg chlorthalidone was observed for up to six months. Assessments at baseline and study endpoints included analysis of adverse events and measurement of systolic and diastolic blood pressure (BP). A total of 3855 patients (53%) received valsartan as monotherapy (mostly as 80 mg once daily), 1162 (16%) received 80 mg valsartan + 12.5 mg chlorthalidone, and 347 (4.8%) received valsartan together with other antihypertensive agents; 858 patients were not evaluable because of inadequate records. A control group of 1034 patients received other antihypertensives. Overall tolerability was high, with 98.5% of patients receiving valsartan alone, 97.7% of those receiving valsartan + chlorthalidone and 92.4% of those receiving other antihypertensives giving tolerability ratings of 'excellent' or 'good'. In this large PMS study, valsartan alone and in combination with chlorthalidone was associated with excellent safety and tolerability in general practice patients in Brazil with primary hypertension, irrespective of age, sex or concomitant diseases.

Cutaneous presentation of follicular lymphomas

The description of primary cutaneous follicular lymphoma has raised interest in the differential diagnosis of this versus disseminated follicular lymphoma involving the skin. We report here on four cases of Stage IV follicular lymphoma, diagnosed in skin biopsy, in which cutaneous lesion was the most noticeable feature of clinical presentation. In all cases, the morphological features were superimposed over typical nodal follicular lymphoma. Apart from classic B-cell markers, they were characterized by CD10 and bcl6 positivity, markers of follicle germinal center cells; and bcl2 expression, with a corresponding t(14;18) translocation in three of three cases examined. In all four cases, bone marrow study and clinical staging revealed disease that had disseminated since diagnosis. Follow-up showed relapsing cutaneous and nodal disease in two cases. The only difference observed with a control group of 10 cases of primary cutaneous follicular lymphoma was the absence in this group of t(14; 18). Disseminated classical follicular lymphoma has to be considered in the differential diagnosis of follicular lymphoma presenting in the skin. This series of cases suggests that the presence of t(14;18) could imply the existence of disease that has disseminated beyond the skin and that cases harboring this translocation could be candidates for systemic polychemotherapy.

P53 and hMSH2 expression in basal cell carcinomas and malignant melanomas from photoexposed areas of head and neck region

Ultraviolet (UV) radiation plays a pivotal role in skin damage and photocarcinogenesis. The basic mechanism of phototoxicity lies in DNA damage, and involves mutation of tumor suppressor genes, oncogenes and genes directly involved in the control of the stability of genome, such as the mismatch repair (MR) genes. The goal of this study was to evaluate the role of p53 and hMSH2 in the UV-related carcinogenetic process. An immunohistochemical study for p53 and hMSH2 was performed in a series of 43 basal cell carcinomas (BCC) and 60 melanomas (MM) from photoexposed areas of head and neck region, comparing the findings with follow-up. A deregulated p53 expression characterized less differentiated, more aggressive BCC (BCC2) but not the well-differentiated ones (BCC1). The hMSH2 protein was present, though expressed at varying levels, in 18 out of 21 BCC1 cases and in 4 out of 22 BCC2. In the remaining 3 cases of BCC1 and 18 cases of BCC2, a complete absence of hMSH2 expression was found, correlating directly with the presence of recurrence and/or death of the disease in case of melanoma (p<0.05). Overall, the expression of hMSH2 correlated inversely with the p53 overexpression (p<0.01). In MM, p53 was found overexpressed in 81.6% of the cases, and this correlated positively with the level of infiltration and with the presence of relapses (p<0.01) or metastasis (p<0.01) and inversely with the disease-free interval (p<0.05). These results are in agreement with the reported association between p53 deregulation and a more aggressive cancer phenotype. The evaluation of the expression of p53 and hMSH2 could improve the management of patients with BCC and MM, and could have a role also in the evaluation of the early cutaneous photo-inducted damage, contributing to the identification of presymptomatic patients predisposed to the development of UV-related new skin tumors, who could become candidates for chemoprevention trials.

Evidence for two mechanisms of amino acid osmolyte release from hippocampal slices

A 30% decrease in osmolarity stimulated 3H-taurine, 3H-GABA and glutamate (followed as 3H-D-aspartate) efflux from rat hippocampal slices. 3H-taurine efflux was activated rapidly but inactivated slowly. It was decreased markedly by 100 microM 5-nitro-(3-phenylpropylamino)benzoic acid (NPPB) and 600 microM niflumic acid and inhibited strongly by tyrphostins AG18, AG879 and AG112 (25-100 microM), suggesting a tyrosine kinase-mediated mechanism. Hyposmolarity activated the mitogen-activated protein kinases (MAPK) extracellular-signal-related kinase-1/2 (ERK1/ERK2) and p38, but blockade of this reaction did not affect 3H-taurine efflux. Hyposmosis also activated phosphatidylinositide 3-kinase (PI3K) and its prevention by wortmannin (100 nM) essentially abolished 3H-taurine efflux. 3H-taurine efflux was insensitive to the protein kinase C (PKC) blocker chelerythrine (2.5 microM) or to cytochalasin E (3 microM). The release of 3H-GABA and 3H-D-aspartate occurred by a different mechanism, characterized by rapid activation and inactivation, insensitivity to NPPB, niflumic acid, tyrphostins or wortmannin. 3H-GABA and 3H-D-aspartate efflux was not due to external [NaCl] decrease, cytosolic Ca2+ increase or depolarization, or to reverse operation of the carrier. This novel mechanism of amino acid release may be mediated by Ca2+-independent exocytosis and modulated by PKC and actin cytoskeleton disruption, as suggested by its inhibition by chelerythrine and potentiation by 100 nM phorbol-12-myristate-13 acetate (PMA) and cytochalasin E. GABA and glutamate osmosensitive efflux may explain the hyposmolarity-elicited increase in amplitude of inhibitory and excitatory postsynaptic potentials in hippocampal slices as well as the hyperexcitability associated with hyponatraemia.

Microvascular coagulopathy and disseminated intravascular coagulation

OBJECTIVE

To review the dual characteristics of disseminated intravascular coagulation (DIC), as both a contributor to multiple organ failure as well as a symptom of severe underlying disease associated with systemic vascular changes.

DATA SOURCES

Published literature data and unpublished results from the authors.

DATA SUMMARY

Clinical and experimental studies strongly suggest that DIC contributes to multiple organ failure and death in patients with severe systemic disorders such as sepsis. DIC is evoked by systemic cytokine activity, and the inflammatory response aggravates vascular permeability, inflammation, and cell damage in tissues. In addition to intravascular fibrin formation, thrombin and fibrin generation in tissues is also an important aspect of DIC. An example of DIC at the organ level is adult respiratory distress syndrome, where fibrin in the lung is a characteristic feature. Intravascular fibrin formation and occlusion may elicit a hypoxic response with induction of hypoxia related transcription factors. The resulting ischemic preconditioning may offer protective effects to the involved organ(s).

CONCLUSIONS

Overall, the beneficial or harmful effects of activated coagulation and fibrin formation for organ pathology and recovery from DIC remain to be explored. This may be a critical element in the assessment of ischemia-reperfusion effects of specific anticoagulant therapy.

Cutaneous follicular B-cell lymphoma: description of a series of 18 cases

The lack of precise and homogeneous criteria for the recognition of primary cutaneous follicular lymphoma has hindered gaining data on the frequency and clinical and molecular features of this entity. In the course of a review of a series of primary cutaneous lymphoma from different Spanish hospitals, we collected a series of 18 cases of primary cutaneous follicular lymphoma and analyzed its clinical, morphologic, and biologic characteristics. In this review only cases with a follicular pattern of growth, germinal center cytology, and restriction to the skin in a minimum follow-up of 6 months have been included. Cases of primary cutaneous follicular lymphoma were characterized by the expression of classic markers of the germinal center, such as bcl6, CD10, and the presence of aggregates of follicular dendritic cells. They frequently express bcl2 protein, although classical t(14;18) was not found in any of the cases analyzed. Analysis of the bcl6 noncoding first exon showed somatic mutations in two of four cases analyzed, as would be expected in lymphoma deriving from the germinal center. Clinically, most cases showed initial involvement of the head and neck, with relapses in eight cases (involving the skin in five cases, both skin and lymph node in two cases, and lymph node in one case). No death attributable to the tumor was recorded. These data seem to imply that follicular lymphoma may present initially in the skin, lacking the characteristic t(14;18) and having a relatively indolent course. Recognition of these tumors and elucidation of their molecular alterations could lead to properly adapted staging and treatment protocols for these patients.

Estrogen receptor beta expression in human prostate tissue

Estrogen receptor subtype beta (ERbeta) is highly expressed in rat prostate epithelium, but its presence in human prostate needs to be confirmed. Here we investigated the expression of ERbeta in five benign (normal and/or hyperplastic) and 10 malignant (Gleasons' score 2-7) prostate tissue specimens using immunohistochemistry. Immunohistochemistry was performed on formalin-fixed, paraffin-embedded tissue sections, using a commercially available ERbeta polyclonal antibody developed against the C-terminal amino acid residue. Nuclear ERbeta expression was found in the nuclei of glandular epithelium of benign prostate tissue specimens; faint nuclear ERbeta positivity was also present in a few stromal cells around normal epithelium. Nuclear ERbeta specific immunostaining was undetectable in all prostate cancer sections.

Comodulation of CXCR4 and CD26 in human lymphocytes

We provide convergent and multiple evidence for a CD26/CXCR4 interaction. Thus, CD26 codistributes with CXCR4, and both coimmunoprecipitate from membranes of T (CD4(+)) and B (CD4(-)) cell lines. Upon induction with stromal cell-derived factor 1alpha (SDF-1alpha), CD26 is cointernalized with CXCR4. CXCR4-mediated down-regulation of CD26 is not induced by antagonists or human immunodeficiency virus (HIV)-1 gp120. SDF-1alpha-mediated down-regulation of CD26 is not blocked by pertussis toxin but does not occur in cells expressing mutant CXCR4 receptors unable to internalize. Codistribution and cointernalization also occurs in peripheral blood lymphocytes. Since CD26 is a cell surface endopeptidase that has the capacity to cleave SDF-1alpha, the CXCR4.CD26 complex is likely a functional unit in which CD26 may directly modulate SDF-1alpha-induced chemotaxis and antiviral capacity. CD26 anchors adenosine deaminase (ADA) to the lymphocyte cell surface, and this interaction is blocked by HIV-1 gp120. Here we demonstrate that gp120 interacts with CD26 and that gp120-mediated disruption of ADA/CD26 interaction is a consequence of a first interaction of gp120 with a domain different from the ADA binding site. SDF-1alpha and gp120 induce the appearance of pseudopodia in which CD26 and CXCR4 colocalize and in which ADA is not present. The physical association of CXCR4 and CD26, direct or part of a supramolecular structure, suggests a role on the function of the immune system and the pathophysiology of HIV infection.

DNA ploidy and cyclin D1 expression in basal cell carcinoma of the head and neck

Basal cell carcinomas (BCCs) may be subdivided into primary with a favorable biologic course (BCC1) and recurrent and/or metastatic (BCC2). No clear association between primary tumor location, histologic subtype, or other clinicopathologic variables and predisposition for BCC2 has been found. Histopathologic criteria are limited for prognostication. To identify prognostic factors useful for planning therapy, we studied cyclin D1 immunohistochemical expression, DNA ploidy, and epiluminescence light microscopic (ELM) patterns in 60 cases of BCC (30 BCC1 and 30 BCC2) in the head and neck region, half of which were hyperpigmented. Cyclin D1 was absent in 27 cases, expressed at low level in 4 cases, and overexpressed in 30 cases. Seven BCCs were euploid, 28 exhibited a mixed cellular population, and 25 were aneuploid. Among aneuploid tumors, hypodiploidy was found in 12. Among the 30 pigmented carcinomas, only 15 showed a typical ELM pattern. No association between pigmentation and more aggressive biologic behavior of BCC was found. These results and follow-up data seem to indicate that an unfavorable outcome can be predicted by hyperexpression of cyclin D1, aneuploidy, and an atypical ELM pattern for pigmented cases. A definite hypodiploid peak was associated with worse prognosis. The analysis of cyclin D1 expression and DNA ploidy may help identify BCC with an aggressive phenotype and a poor clinical outcome.

Metabotropic glutamate 1alpha and adenosine A1 receptors assemble into functionally interacting complexes

Recently, evidence has emerged that seven transmembrane G protein-coupled receptors may be present as homo- and heteromers in the plasma membrane. Here we describe a new molecular and functional interaction between two functionally unrelated types of G protein-coupled receptors, namely the metabotropic glutamate type 1alpha (mGlu(1alpha) receptor) and the adenosine A1 receptors in cerebellum, primary cortical neurons, and heterologous transfected cells. Co-immunoprecipitation experiments showed a close and subtype-specific interaction between mGlu(1alpha) and A1 receptors in both rat cerebellar synaptosomes and co-transfected HEK-293 cells. By using transiently transfected HEK-293 cells a synergy between mGlu(1alpha) and A1 receptors in receptor-evoked [Ca(2+)](i) signaling has been shown. In primary cultures of cortical neurons we observed a high degree of co-localization of the two receptors, and excitotoxicity experiments in these cultures also indicate that mGlu(1alpha) and A1 receptors are functionally related. Our results provide a molecular basis for adenosine/glutamate receptors cross-talk and open new perspectives for the development of novel agents to treat neuropsychiatric disorders in which abnormal glutamatergic neurotransmission is involved.

Substitution of murine ferrochelatase glutamate-287 with glutamine or alanine leads to porphyrin substrate-bound variants

Ferrochelatase (EC 4.99.1.1) is the terminal enzyme of the haem biosynthetic pathway and catalyses iron chelation into the protoporphyrin IX ring. Glutamate-287 (E287) of murine mature ferrochelatase is a conserved residue in all known sequences of ferrochelatase, is present at the active site of the enzyme, as inferred from the Bacillus subtilis ferrochelatase three-dimensional structure, and is critical for enzyme activity. Substitution of E287 with either glutamine (Q) or alanine (A) yielded variants with lower enzymic activity than that of the wild-type ferrochelatase and with different absorption spectra from the wild-type enzyme. In contrast to the wild-type enzyme, the absorption spectra of the variants indicate that these enzymes, as purified, contain protoporphyrin IX. Identification and quantification of the porphyrin bound to the E287-directed variants indicate that approx. 80% of the total porphyrin corresponds to protoporphyrin IX. Significantly, rapid stopped-flow experiments of the E287A and E287Q variants demonstrate that reaction with Zn(2+) results in the formation of bound Zn-protoporphyrin IX, indicating that the endogenously bound protoporphyrin IX can be used as a substrate. Taken together, these findings suggest that the structural strain imposed by ferrochelatase on the porphyrin substrate as a critical step in the enzyme catalytic mechanism is also accomplished by the E287A and E287Q variants, but without the release of the product. Thus E287 in murine ferrochelatase appears to be critical for the catalytic process by controlling the release of the product.

Involvement of caveolin in ligand-induced recruitment and internalization of A(1) adenosine receptor and adenosine deaminase in an epithelial cell line

Chronic exposure of A(1) adenosine receptors (A(1)R) to A(1)R agonists leads to activation, phosphorylation, desensitization, and internalization to intracellular compartments of the receptor. Desensitization and internalization of A(1)R is modulated by adenosine deaminase (ADA), an enzyme that regulates the extracellular concentration of adenosine. ADA interacts with A(1)R on the cell surface of the smooth muscle cell line DDT1 MF-2, and both proteins are internalized following agonist stimulation of the receptor. The mechanism involved in A(1)R and ADA internalization upon agonist exposure is poorly understood in epithelial cells. In this report, we show that A(1)R and ADA interact in LLC-PK(1) epithelial cells. Exposure of LLC-PK(1) cells to A(1)R agonists induces aggregation of A(1)R and ADA on the cell surface and their translocation to intracellular compartments. Biochemical and cell biology assays were used to characterize the intracellular vesicles containing both proteins after agonist treatment. A(1)R and ADA colocalized together with the rafts marker protein caveolin. Filipin, a sterol-binding agent that disrupts rafts (small microdomains of the plasma membrane), was able to inhibit A(1)R internalization. In contrast, acid treatment of the cells, which disrupts internalization via clathrin-coated vesicles, did not inhibit agonist-stimulated A(1)R internalization. We demonstrated that A(1)R agonist N(6)-(R)-phenylisopropyl adenosine promotes the translocation of A(1)R into low-density gradient fractions containing caveolin. Furthermore, a direct interaction of the C-terminal domain of A(1)R with caveolin-1 was demonstrated by pull down experiments. These results indicate that A(1)R and ADA form a stable complex in the cell surface of LLC-PK(1) cells and that agonist-induced internalization of the A(1) adenosine receptor and ADA is mediated by clathrin-independent endocytosis.

Amino acid osmolytes in regulatory volume decrease and isovolumetric regulation in brain cells: contribution and mechanisms

Brain adaptation to hyposmolarity is accomplished by loss of both electrolytes and organic osmolytes, including amino acids, polyalcohols and methylamines. In brain in vivo, the organic osmolytes account for about 35% of the total solute loss. This review focus on the role of amino acids in cell volume regulation, in conditions of sudden hyposmosis, when cells respond by active regulatory volume decrease (RVD) or after gradual exposure to hyposmotic solutions, a condition where cell volume remains unchanged, named isovolumetric regulation (IVR). The amino acid efflux pathway during RVD is passive and is similar in many respects to the volume-activated anion pathway. The molecular identity of this pathway is still unknown, but the anion exchanger and the phospholemman are good candidates in certain cells. The activation trigger of the osmosensitive amino acid pathway is unclear, but intracellular ionic strength seems to be critically involved. Tyrosine protein kinases markedly influence amino acid efflux during RVD and may play an important role in the transduction signaling cascades for osmosensitive amino acid fluxes. During IVR, amino acids, particularly taurine are promptly released with an efflux threshold markedly lower than that of K(+), emphasizing their contribution (possibly as well as of other organic osmolytes) vs inorganic ions, in the osmolarity range corresponding to physiopathological conditions. Amino acid efflux also occurs in response to isosmotic swelling as that associated with ischemia or trauma. Characterization of the pathway involved in this type of swelling is hampered by the fact that most osmolyte amino acids are also neuroactive amino acids and may be released in response to stimuli concurrent with swelling, such as depolarization or intracellular Ca(++) elevation.

Variations of proline-rich kinase Pyk2 expression correlate with prostate cancer progression

Proline-rich kinase 2 (Pyk2), also known as CAKbeta (cell adhesion kinase beta), is a cytoplasmic tyrosine kinase that is structurally related to focal adhesion kinase. Pyk2 is expressed in different cell types including brain cells, fibroblasts, platelets, and other hemopoietic cells. Pyk2 is rapidly tyrosine phosphorylated in response to diverse extracellular signals acting via different post receptor pathways. We have investigated whether this protein kinase is functionally expressed in normal and neoplastic prostate tissues. In this study, we demonstrate that Pyk2 is expressed only in normal epithelial prostate tissue and in benign prostatic hyperplasia, whereas its expression progressively declines with an increasing grade of malignancy of prostate cancer.

Adenosine A2B receptors behave as an alternative anchoring protein for cell surface adenosine deaminase in lymphocytes and cultured cells

Adenosine deaminase (ADA) is an enzyme of the purine metabolism that has been largely considered to be cytosolic. Recently, it has been demonstrated that the enzyme appears on the surface of lymphocytes where it interacts with the T-cell activation antigen CD26. ADA also appears on the surface of nonlymphoid cells anchored to adenosine A1 receptors. Here it is demonstrated that cell surface ADA in ADA+/CD26- T lymphocytes anchors to adenosine receptors of the A2B subtype (A2BR). An interaction between A2BR and cell surface ADA has been demonstrated in transfected Chinese hamster ovary cells and Jurkat J32 T lymphocytes. This has been proved by coimmunoprecipitation, binding of exogenous ADA to A2BR+ cells, and coimmunolocalization. The specificity of the interaction has also been demonstrated by the lack of interaction with other members of the G protein-coupled receptor superfamily. Binding of ADA to A2BR increases the affinity of the agonist 5'-N-ethylcarboxamidoadenosine and cAMP production. This effect occurs even when ADA devoid of enzyme activity is used. Therefore, in lymphocytes, cell surface ADA, apart from degrading extracellular adenosine, regulates those actions of adenosine that are mediated via adenosine receptors of the A2B subtype.

Evidence for adenosine/dopamine receptor interactions: indications for heteromerization

Evidence has been obtained for adenosine/dopamine interactions in the central nervous system. There exists an anatomical basis for the existence of functional interactions between adenosine A(1)R and dopamine D(1)R and between adenosine A(2A) and dopamine D(2) receptors in the same neurons. Selective A(1)R agonists affect negatively the high affinity binding of D(1) receptors. Activation of A(2A) receptors leads to a decrease in receptor affinity for dopamine agonists acting on D(2) receptors, specially of the high-affinity state. These interactions have been reproduced in cell lines and found to be of functional significance. Adenosine/dopamine interactions at the behavioral level probably reflect those found at the level of dopamine receptor binding and transduction. All these findings suggest receptor subtype-specific interactions between adenosine and dopamine receptors that may be achieved by molecular interactions (e.g., receptor heterodimerization). At the molecular level adenosine receptors can serve as a model for homomeric and heteromeric protein-protein interactions. A1R forms homodimers in membranes and also form high-order molecular structures containing also heterotrimeric G-proteins and adenosine deaminase. The occurrence of clustering also clearly suggests that G-protein- coupled receptors form high-order molecular structures, in which multimers of the receptors and probably other interacting proteins form functional complexes. In view of the occurrence of homodimers of adenosine and of dopamine receptors it is speculated that heterodimers between these receptors belonging to two different families of G-protein-coupled receptors can be formed. Evidence that A1/D1 can form heterodimers in cotransfected cells and in primary cultures of neurons has in fact been obtained. In the central nervous system direct and indirect receptor-receptor interactions via adaptor proteins participate in neurotransmission and neuromodulation and, for example, in the establishment of high neural functions such as learning and memory.

Estradiol-induced mitogen-activated protein kinase (extracellular signal-regulated kinase 1 and 2) activity in the frog (Rana esculenta) testis

Several lines of evidence support a key role of estradiol-17beta (E(2)) in male fertility. We have used a non-mammalian vertebrate model, the frog Rana esculenta, to investigate the regulation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) activity in the testis during the annual sexual cycle and to study whether E(2 )exerts a role in spermatogenesis through the regulation of ERK1/2 activity. ERK1/2 proteins are present in the cytoplasm and nucleus of the primary and secondary spermatogonia (SPG), and in the nucleus of primary spermatocytes. The annual E(2) profile shows a progressive increase during active spermatogenesis with a peak in the month of June. In parallel, ERK1/2 are highly phosphorylated during the period of active spermatogenesis (from April to July) compared with the regressive period (September/October) and winter stasis (from November to March). E(2) treatment induces the proliferation of primary SPG, possibly via the activation of ERK1/2, and this effect is counteracted by the anti-estrogen ICI 182-780.

Efflux of osmolyte amino acids during isovolumic regulation in hippocampal slices

The efflux of potassium (K(+)) and amino acids from hippocampal slices was measured after sudden exposure to 10% (270 mOsm), 25% (225 mOsm) or 50% (150 mOsm) hyposmotic solutions or after gradual decrease (-2.5 mOsm/min) in external osmolarity. In slices suddenly exposed to 50% hyposmotic solutions, swelling was followed by partial (74%) cell volume recovery, suggesting regulatory volume decrease (RVD). With gradual hyposmotic changes, no increase in cell water content was observed even when the solution at the end of the experiment was 50% hyposmotic, showing the occurrence of isovolumic regulation (IVR). The gradual decrease in osmolarity elicited the efflux of (3)H-taurine with a threshold at -5 mOsm and D-[(3)H]aspartate (as marker for glutamate) and at -20 mOsm for [(3)H]GABA. The efflux rate of [(3)H]taurine was always notably higher than those of [(3)H]GABA and D-[(3)H]aspartate, with a maximal increase over the isosmotic efflux of about 7-fold for [(3)H]taurine and 3- and 2-fold for [(3)H]GABA and D-[(3)H]aspartate, respectively. The amino acid content in slices exposed to 50% hyposmotic solutions (abrupt change) during 20 min decreased by 50. 6% and 62.6% (gradual change). Taurine and glutamate showed the largest decrease. An enhancement in (86)Rb efflux and a corresponding decrease in K(+) tissue content was seen in association with RVD but not with IVR. These results demonstrate the contribution of amino acids to IVR and indicate their involvement in this mechanism of cell volume control.

Immunolocalization of A1 adenosine receptors in mammalian spermatozoa

The presence of A1 adenosine receptors (A1AR) in mammalian spermatozoa was previously demonstrated by radiochemical and immunochemical detection. This study was performed to investigate the cellular location of the A1AR to determine whether these receptors were somehow connected with ecto-adenosine deaminase and to evaluate their function in calcium uptake. By immunofluorescence staining we showed that in mammalian spermatozoa A1AR were constantly localized in the acrosomal region. This finding was confirmed by immunogold detection. Confocal analyses with anti-A1 and anti-ADA antibodies showed a high degree of co-localization. Calcium loading assay showed that this association was functional and affected calcium accumulation in mammalian spermatozoa. Therefore, we concluded that the acrosomal localization of A1AR was a constant feature in mammalian sperm. Moreover, these A1 receptors were functionally coupled to ecto-ADA and were able to modulate calcium uptake into an IP3-gated store.(J Histochem Cytochem 48:1163-1171, 2000)

Adenosine A(1) receptor in cultured neurons from rat cerebral cortex: colocalization with adenosine deaminase

Adenosine A(1) receptors (A(1)Rs) have been characterized in primary cultures of neurons from cerebral cortex. The specific adenosine A(1) antagonist 8-cyclopentyl-1,3-[(3)H]dipropylxanthine bound to both membranes and intact cells. When saturation experiments were performed in membranes, a K(D) value of 0.76 nM and a B(max) of 57 fmol/mg of protein were obtained. Competition assays revealed a pharmacological profile characteristic of A(1)Rs. The presence of this receptor was further confirmed by RT-PCR analysis. The expression of the receptor showed no significant changes during the period of culture studied, up to 12 days in vitro. A(1)R agonist inhibited forskolin-stimulated adenylyl cyclase, showing the functional coupling of these receptors with the effector. alphaG(i1, 2) protein level, detected by immunoblot, presented an increase during the period of culture. This increase correlated with an increase in the mRNA level of alphaG(i1) but not alphaG(i2). By immunochemical assays, it is shown that these receptors are expressed in both the neuronal cell body and the proximal dendrites. Colocalization of A(1)Rs with microtubule-associated protein 2 and cell surface adenosine deaminase was shown by confocal microscopy. The high degree of colocalization observed between A(1)Rs and ectoadenosine deaminase in neurons could suggest an important role of the enzyme in adenosine-mediated neuromodulation.

Dopamine D1 and adenosine A1 receptors form functionally interacting heteromeric complexes

The possible molecular basis for the previously described antagonistic interactions between adenosine A(1) receptors (A(1)R) and dopamine D(1) receptors (D(1)R) in the brain have been studied in mouse fibroblast Ltk(-) cells cotransfected with human A(1)R and D(1)R cDNAs or with human A(1)R and dopamine D(2) receptor (long-form) (D(2)R) cDNAs and in cortical neurons in culture. A(1)R and D(1)R, but not A(1)R and D(2)R, were found to coimmunoprecipitate in cotransfected fibroblasts. This selective A(1)R/D(1)R heteromerization disappeared after pretreatment with the D(1)R agonist, but not after combined pretreatment with D(1)R and A(1)R agonists. A high degree of A(1)R and D(1)R colocalization, demonstrated in double immunofluorescence experiments with confocal laser microscopy, was found in both cotransfected fibroblast cells and cortical neurons in culture. On the other hand, a low degree of A(1)R and D(2)R colocalization was observed in cotransfected fibroblasts. Pretreatment with the A(1)R agonist caused coclustering (coaggregation) of A(1)R and D(1)R, which was blocked by combined pretreatment with the D(1)R and A(1)R agonists in both fibroblast cells and in cortical neurons in culture. Combined pretreatment with D(1)R and A(1)R agonists, but not with either one alone, substantially reduced the D(1)R agonist-induced accumulation of cAMP. The A(1)R/D(1)R heteromerization may be one molecular basis for the demonstrated antagonistic modulation of A(1)R of D(1)R receptor signaling in the brain. The persistence of A(1)R/D(1)R heteromerization seems to be essential for the blockade of A(1)R agonist-induced A(1)R/D(1)R coclustering and for the desensitization of the D(1)R agonist-induced cAMP accumulation seen on combined pretreatment with D(1)R and A(1)R agonists, which indicates a potential role of A(1)R/D(1)R heteromers also in desensitization mechanisms and receptor trafficking.

The HIV-1 gp120 inhibits the binding of adenosine deaminase to CD26 by a mechanism modulated by CD4 and CXCR4 expression

HIV-1 external envelope glycoprotein gp120 inhibits adenosine deaminase (ADA) binding to its cell surface receptor in lymphocytes, CD26, by a mechanism that does not require the gp120-CD4 interaction. To further characterize this mechanism, we studied ADA binding to murine clones stably expressing human CD26 and/or human CD4, and transiently expressing human CXCR4. In this heterologous model, we show that both recombinant gp120 and viral particles from the X4 HIV-1 isolate IIIB inhibited the binding of ADA to wild-type or catalytically inactive forms of CD26. In cells lacking human CXCR4 expression, this gp120-mediated inhibition of ADA binding to human CD26 was completely dependent on the expression of human CD4. In contrast, when cells were transfected with human CXCR4 the inhibitory effect of gp120 was significantly enhanced and was not blocked by anti-CD4 antibodies. These data suggest that the interaction of gp120 with CD4 or CXCR4 is required for efficient inhibition of ADA binding to CD26, although in the presence of CXCR4 the interaction of gp120 with CD4 may be dispensable.

PCNA in the testis of the frog, Rana esculenta: a molecular marker of the mitotic testicular epithelium proliferation

Proliferating cell nuclear antigen (PCNA) plays an essential role in nucleic acid metabolism as a component of the replication and repair machinery. This toroidal-shaped protein encircles DNA and can slide bidirectionally along the duplex. One of the well-established functions for PCNA is its role as the processing factor for DNA polymerase delta and epsilon. It has become apparent that PCNA interacts with proteins involved in the cell cycle. The PCNA interactions with different cellular proteins and the importance of these interactions are also discussed. To examine the different mitotic testicular epithelium proliferation during the annual discontinuous frog (Rana esculenta) spermatogenesis, the temporal and the spatial PCNA expression are described and give a useful endogenous molecular marker.

The heat shock cognate protein hsc73 assembles with A(1) adenosine receptors to form functional modules in the cell membrane

A(1) adenosine receptors (A(1)Rs) are G protein-coupled heptaspanning receptors that interact at the outer face of the plasma membrane with cell surface ecto-adenosine deaminase (ecto-ADA). By affinity chromatography the heat shock cognate protein hsc73 was identified as a cytosolic component able to interact with the third intracellular loop of the receptor. As demonstrated by surface plasmon resonance, purified A(1)Rs interact specifically with hsc73 with a dissociation constant in the nanomolar range (0.5 +/- 0.1 nM). The interaction between hsc73 and A(1)R led to a marked reduction in the binding of the ligands and prevented activation of G proteins, as deduced from (35)S-labeled guanosine-5'-O-(3-thio)triphosphate binding assays. Interestingly this effect was stronger than that exerted by guanine nucleotide analogs, which uncouple receptors from G proteins, and was completely prevented by ADA. As assessed by immunoprecipitation a high percentage of A(1)Rs in cell lysates are coupled to hsc73. A relatively high level of colocalization between A(1)R and hsc73 was detected in DDT(1)MF-2 cells by means of confocal microscopy, and no similar results were obtained for other G protein-coupled receptors. Colocalization between hsc73 and A(1)R was detected in specific regions of rat cerebellum and in the body of cortical neurons but not in dendrites or synapses. Remarkably, agonist-induced receptor internalization leads to the endocytosis of A(1)Rs by two qualitatively different vesicle types, one in which A(1)R and hsc73 colocalize and another in which hsc73 is absent. These results open the interesting possibility that signaling via G protein-coupled receptors may be regulated by heat shock proteins.

Mechanisms of CD26/dipeptidyl peptidase IV cytokine-dependent regulation on human activated lymphocytes

Among the cellular pathways activated by IL-12, we had previously found that both the percentage and intensity of CD26(+)cells in the PHA-stimulated T cells increased when IL-12 was present (independently of its CD4 or CD8 phenotype). Now, we examined the molecular mechanisms of this IL-12-mediated effect. The IL-12 regulation pathway is dependent of de novo protein synthesis and independent of cytokine secretion. Our results show two transcripts for CD26 in PBMC for the first time and no regulation by ILs at this level. Furthermore, secretion of the serum forms of CD26/DPPIV were not affected by IL-12. Interestingly, assays with neutralizing mAbs against TNF-alpha suggest that this cytokine negatively modulates CD26 expression. The fact that translation and probably translocation of CD26 toward the cell surface can be regulated by IL-12 and TNF-alpha reveals new aspects about the control of this T(H1)marker.

Amyloid goiter: the first evidence in secondary amyloidosis. Report of five cases and review of literature

Amyloid deposition in secondary amyloidosis frequently involves thyroid gland, but rarely is responsible of a goiter. Amyloid goiter in secondary amyloidosis is characterized by deposition of amyloid A protein (AA) in the gland, associated to atrophic follicles. We identified cases of amyloid goiter in the files of our department in the period from 1985 to 1998. Five cases of amyloid goiter with ingravescent symptomatology, characterized by dyspnea, dysphagia and hoarseness were selected. In four cases of five we observed predisposing conditions as, for example, tuberculosis, Crohn's disease, or rheumatoid arthritis. In all cases the symptoms relative to thyroid enlargement preceded or, anyway, predominated over other clinical evidence of systemic amyloidosis. In one case a symptomatology of systemic amyloidosis was not evident. We would like to underline that in all cases the immunoreactivity for amyloid A in the amorphous material present in the gland permitted the diagnosis of secondary amyloidosis even in the absence of systemic symptoms.

Porphyrin interactions with wild-type and mutant mouse ferrochelatase

Ferrochelatase (EC 4.99.1.1), the terminal enzyme of the heme biosynthetic pathway, catalyzes Fe(2+) chelation into protoporphyrin IX. Resonance Raman and UV-vis absorption spectroscopies of wild-type and engineered variants of murine ferrochelatase were used to examine the proposed structural mechanism for iron insertion into porphyrin. The recombinant variants (i.e., H207N and E287Q) are enzymes in which the conserved amino acids histidine-207 and glutamate-287 of murine ferrochelatase were substituted with asparagine and glutamine, respectively. Both of these residues are at the active site of the enzyme as deduced from the Bacillus subtilis ferrochelatase three-dimensional structure. On the basis of changes in the UV-vis absorption spectrum, addition of free-base or metalated porphyrins to wild-type ferrochelatase and H207N variant yields a 1:1 complex, most likely a monomeric protein-bound species at the active site. In contrast, the addition of porphyrin (either free base or metalated) to E287Q is substoichiometric, as this variant retains bound porphyrin in the active site during isolation and purification. The specificity of porphyrin binding is confirmed by the narrowing of the structure-sensitive lines and the vinyl vibrational mode in the resonance Raman spectra. Shifts in the resonance Raman lines of free-base and metalated porphyrins bound to the wild-type ferrochelatase indicate a nonplanar distortion of the porphyrin macrocycle. However, the magnitude of the distortion cannot be determined without first defining the specific type of deformation. Significantly, the extent of the nonplanar distortion varies in the case of H207N- and E287Q-bound porphyrins. In fact, resonance Raman spectral decompositions indicate a homogeneous ruffled deformation for the nickel protoporphyrin bound to the wild-type ferrochelatase, whereas both planar and ruffled conformations are present for the H207N-bound porphyrin. Perhaps more revealing is the unusual resonance Raman spectrum of the endogenous E287Q-bound porphyrin, which has the structure-sensitive lines greatly upshifted relative to those of the free-base protoporphyrin in solution. This could be interpreted as an equilibrium between protein conformers, one of which favors a highly distorted porphyrin macrocycle. Taken together, these findings suggest that distortion occurs in murine ferrochelatase for some porphyrins, even without metal binding, which is apparently required for the yeast ferrochelatase.

Integrated control of acaricide-resistant Boophilus microplus populations on grazing cattle in Mexico using vaccination with Gavac and amidine treatments

Throughout most of the twentieth century, tick infestations on cattle have been controlled with chemical acaricides, typically administered by dipping or spraying. This approach can cause environmental and residue problems and has created a high incidence of acaricide resistance within tick populations in the field. Recently we developed a vaccine against Boophilus microplus employing a recombinant Bm86 antigen preparation (Gavac), (Heber Biotec S.A., Havana, Cuba) which has been shown to induce a protective response in vaccinated animals. Here we show for the first time under field conditions a near 100% control of B. microplus populations resistant to pyrethroids and organophosphates, by an integrated system employing vaccination with Gavac and amidine treatments. This method effectively controls tick infestations while reducing the number of chemical acaricide treatments and consequently the rise of B. microplus populations resistant to chemical acaricides.