Adenosine increases human platelet levels of cGMP through nitric oxide: possible role in its antiaggregating effect

Adenosine is an endogenous antiaggregating substance that influences the platelet responses through specific A-type receptors that activate adenylate cyclase increasing the levels of 3',5'-cyclic adenosine monophosphate (cAMP). In this study, we investigated whether adenosine can also influence the levels of 3',5'-cyclic guanosine monophosphate (cGMP) and decrease the aggregating response of human platelets to adenosine-5-diphosphate (ADP) through this nucleotide. In platelet samples from healthy volunteers, we evaluated the effect of adenosine on ADP-induced aggregation and cyclic nucleotide synthesis. Some experiments were repeated in the presence of dipyridamole (inhibitor of adenosine uptake and phosphodiesterase activity), N(G)-monomethyl-L-arginine (L-NMMA, nitric synthase inhibitor), ionomycin (calcium ionophore), and ambroxol (2-amino-3,5-dibromo-N-[trans-4-hydroxycyclohexyl]benzylamine, inhibitor of nitric oxide (NO)-dependent activation of guanylate cyclase). Adenosine decreased the response to ADP in a concentration-dependent way (analysis of variance, ANOVA: P<.0001): cAMP levels increased from 30.0 +/- 2.0 (control) to 46.0 +/- 3.0 pmol/10(9) platelets (in the presence of 15 mumol/l adenosine) and cGMP levels increased from 5.6 +/- 1.0 (control) to 10.9 +/- 2.0 pmol/10(9) platelets (in the presence of 15 mumol/l adenosine). Also, nucleotide levels measured at the end of aggregation were higher in platelet samples exposed to adenosine than in controls. Dipyridamole at 40 mumol/l slightly increased adenosine's effects on both nucleotides. L-NMMA blunted the effect of adenosine on cGMP both in unstimulated samples and in aggregated platelets without any effect on cAMP synthesis. Platelet exposure to L-NMMA and ambroxol partially prevented adenosine's effect on ADP-induced aggregation. In conclusion, adenosine, which enhances intraplatelet cAMP levels, was determined to also cause an increase in cGMP concentrations through a mechanism that involves NO synthesis. This effect plays a direct role in the adenosine-induced antiaggregation.     

Reversible cerebral perfusion alterations in children with transient mutism after posterior fossa surgery

Mutism is an infrequent and transitory complication observed following posterior fossa surgery. Patients become mute in the immediate postoperative period, with restoration of speech within a few weeks in the absence of additional neurological alterations. The anatomical structures thought to be involved are the connections between the cerebellar dentate nucleus, the ventrolateral nucleus of the contralateral thalamus and the supplementary motor area. In an attempt to understand the pathophysiology of this syndrome, and to depict the perfusion of different brain areas semiquantitatively, in two children who had become mute after posterior fossa surgery we performed a Tc99M-HM-PAO SPECT study during the period of mutism and again when normal speech had returned. In one patient, who had a left cerebellar astrocytoma, the SPECT study showed a marked reduction of cerebral perfusion in the right fronto-parietal region, and in the other, who had a medulloblastoma, a left fronto-temporo-parietal perfusion alteration was observed. When the patients regained normal speech, the follow-up SPECT studies revealed normalization of the cerebral perfusion. This study demonstrates the occurrence of a focal dysfunction of cerebral perfusion in children with cerebellar mutism after posterior fossa surgery. These observations are useful in extending our understanding of the pathophysiology of this postoperative clinical syndrome. Received: 12 September 1997 Revised: 17 November 1997     

Psychopathologic patterns in obesity

The problem of relationship between obesity and psychological distress is debated in the literature wherein a lot of studies exists with controversial results. The phenomenon of obesity is actually considered with criteria aimed to evaluate almost exclusively the weight excess. Even if such criteria have the advantage to permit a scientific communicability, in the clinical settings the focus of obesity involves medical as well psychiatric aspects. The psychological aspects that may have a relevant role in the development of obesity must be recognized and distinguished from those that may be a direct consequence of obesity itself. In fact, certain obese subjects (no-binge obese) may not experience any psychological distress during lifetime whereas other obese subjects (binge obese) may have a significant and highly distressing psychological suffering. Therefore, obese persons seem to represent a heterogeneous population with different adaptive characteristics who may show several and complex psychological mechanisms and distresses. A psychotherapeutic approach seems to be essential to treat such psychological distress that may heavily concur to the development and the maintenance of obesity.     

Guidelines for health surveillance of health care workers exposed to biological risks set up by the Italian Society for Occupational Health and Industrial Hygiene: application in health facilities of the Regional Health Administration--District No. 7, Ancona

BACKGROUND: Evidence Based Medicine and the need to achieve better management of health budgets call for verification and, if necessary, revision of the criteria used in Occupational Health, in order to ensure appropriate measures as regards protection of health at the workplace. In December 2003, the Marche Region initiated a process of reform of the regional health service, which will be completed in two years, and will provide a new regional health organization that will improve the quality and appropriateness of health services available to the population. The reform also involves the Occupational Health Services responsible for prevention activities for 20,000 health care workers employed in regional public health facilities. The need was strongly felt to set up a network that would meet the health needs of health care workers, by adopting a common language among occupational health physicians, by eliminating reported criticism, which is due not only to lack of communication between different structures and profiles, but also to the different methods of approach, evaluation and management of occupational risks. OBJECTIVES AND METHODS: From a historical point of view, the health sector has the biggest as regards prevention of biological risk. Therefore, with a view to harmonizing actions and approach among occupational health physicians in the evaluation of this risk, the publication by the Italian Society for Occupational of Health and Industrial Hygiene of Guidelines for health surveillance of health care workers exposed to biological risks, produced by the working group under the leadership of Prof. Lorenzo Alessio, was considered to offer an interesting opportunity to verify the reproducibility of methods and the quality of results, as applied to health facilities under the Regional Health Administration in Ancona (District No. 7). RESULTS AND CONCLUSION: The Guidelines fully confirmed the need to plan activities, starting from analysis of epidemiological and occupational data, thus assuring good results both in terms of efficacy and efficiency of the health surveillance programme used. This method also assures a high level of appropriateness of medical measures as regards the "safety" target, at the same time avoiding waste and poor management of human and economic resources, which were till now caused by differences in methods used in assessment of biological risk.     

Testicular microlithiasis: an unreported feature of McCune-Albright syndrome in males

OBJECTIVE: To ascertain the incidence of testicular microlithiasis (TM) in boys with McCune-Albright syndrome (MAS). STUDY DESIGN: Study population consisted of 8 boys with MAS whose medical records were reviewed with emphasis on their past genitourinary histories. All of the boys underwent a clinical and ultrasonographic (US) scanning of the scrotal and inguinal regions. US results in boys with MAS were compared with those obtained in two control populations consisting of 20 healthy subjects and 12 boys with idiopathic and untreated central precocious puberty (CPP). RESULTS: Clinical examination revealed urological abnormalities in no patients, whereas US showed a typical picture of TM in 5 of 8 boys. TM was observed in none of the subjects belonging to control populations (v=15.2 and 11.3, respectively; P <.001). CONCLUSIONS: In a series of 8 boys with MAS we demonstrated a high prevalence (62%) of TM that was associated with neither malignant nor nonmalignant conditions. This finding is unlikely to be only occasional, considering the very low prevalence of TM reported until now in healthy children and young adults and in our results in control populations. TM may be another marker for MAS.     

Outcome of low-dose ganciclovir for cytomegalovirus disease prophylaxis in renal-transplant recipients

To assess the outcome of low-dose-ganciclovir prophylaxis (500 mg twice a day for 3 months) in renal-transplant recipients, a retrospective analysis of 185 patients transplanted between 1998 and 2001 was performed. There were 29 (15.6%) patients who belonged to the highest risk group, donor cytomegalovirus (CMV) positive, recipient negative (D + R-), and 37 (20%) patients in the lowest risk group, D-R-. Induction immunosuppression consisted of polyclonal antibody or OKT3 (n = 62, 33.5%), interleukin-2 receptor antibody (n = 61, 33%), and no induction (n = 62, 33.5%). CMV disease occurred in 13 (7%) patients. Highest incidence was in D + R- group (17.2%), with no cases in D-R- group (P = 0.03). Tissue-invasive CMV occurred in 4 of these 13 patients. In patients developing CMV disease, there was no evidence of ganciclovir resistance and no mortality over a mean follow-up of 42 months. Low-dose ganciclovir was found to be as effective in decreasing the incidence of clinical CMV disease as high-dose ganciclovir (1 gm three times a day for 3-6 months) in previous studies.     

Cucurbitane triterpenoids from Leucopaxillus gentianeus

In addition to the known bioactive triterpene cucurbitacin B (1), two new cucurbitane triterpenoids, namely, leucopaxillones A (3) and B (4), exhibiting a new oxygenation pattern among cucurbitacins, have been isolated from the mushroom Leucopaxillus gentianeus (syn. L. amarus). Cucurbitacin B (1) imparts a bitter taste to the flesh of the fungus; however, it occurs in the fruiting bodies mainly esterified as tasteless fatty acid esters 2a-c. In vitro growth inhibitory effects of compounds 1-4 on proliferation of four different human tumor cell lines (A549, CAKI-1, HepG2, MCF-7) were evaluated by using a 1-day MTT assay. Only cucurbitacin B was highly active on all lines. Free cucurbitacin B is presumed to be formed in vivo by an enzyme-mediated scission of esters 2a-c, thus constituting a chemical weapon that protects the mushrooms against parasites and predators. Compounds 1-4 are structurally different from the other few cucurbitacins isolated from Basidiomycetes, being, instead, more similar to those occurring in plants. In particular, cucurbitacin B (1) seems to represent an interesting example of secondary metabolite convergence between distant taxa such as fungi and vascular plants, where they likely exert a similar role of protection. The structures of the compounds were established by means of spectroscopic methods and X-ray diffraction on a single crystal. The absolute configuration of leucopaxillone A has been assigned on the basis of CD chirality rules.     

Enhanced efficacy of tumor cell vaccines transfected with secretable hsp70

Tumor immunotherapy has exploited the ability of heat shock proteins to chaperone precursors of antigenic peptides to antigen-presenting cells and to activate efficiently an immune response against tumor-associated antigens. The most common strategy is based on the purification of heat shock protein-peptide complexes from tumor cell lines or from tumor surgical samples for in vivo administration. In this article, we have modified the murine-inducible hsp70 into a secreted protein and engineered tumor cells to secrete constitutively their antigenic repertoire associated with the hsp70 protein. In vitro studies showed that the relocalization of hsp70 from the cytoplasm to the secretory pathway did not modify the ability of hsp70 to interact with peptides derived either from natural tumor-associated antigens or model antigens, and that antigen-presenting cells specifically took up the secreted hsp70 and presented the chaperoned epitopes to T cells. In vivo studies showed that tumors secreting hsp70 displayed increased immunogenicity, with induction of a strong and specific CTL response. Mice injected with hsp70-secreting tumors showed increased survival and impaired tumor take compared with mice bearing parental tumors. More than 70% of mice rejected tumor cells secreting hsp70 through mechanisms that involve T lymphocytes and natural killer cells, with the induction of a memory response in the case of T lymphocytes. Moreover, hsp70 secretion increased the immunogenic potential of tumor cell vaccines.     

Advantages and limits of percutaneous breast core biopsy with Mammotome and stereotactic equipment in upright seated patient

PURPOSE: To confirm the diagnostic accuracy of percutaneous core breast biopsy with Mammotome and stereotactic equipment in upright seated patients, and to compare results from this method with those obtained using the dedicated unit with prone table. MATERIALS AND METHODS: We analysed 72 microbioptic samples from 69 upright seated patients. These samples were obtained in the course of mammographies assisted by digital stereotactic equipment (Diamond Delta32 General Electric Medical System/Instrumen-tarium), and further equipped with a lateral arm to support the Mammotone probe. We studied the following lesions: 57 cases of isolated microcalcification clusters, 12 masses with microcalcification and three cases of plain masses. We describe in detail the various phases of our 30-minute long microbiopsy procedure. All 72 samples were extracted without problems. Only in one case a large haematoma emerged, but quickly disappeared. RESULTS: We were able to characterise the histology of the lesions in all our samples: in 39/72 cases they were identified as benign, 28 were classified as malignant, and the remaining 5 as atypia. In the 39 lesions identified as benign, the microbiopsy procedure could be carried out without surgical biopsy - consequently, these patients were available for routine follow-up exams, which confirmed the benign nature of their lesions. Our identification of the 28 malignant lesions was confirmed by surgical biopsy. The microbiopsy finding and the histological result did not agree in only two cases. The 5 cases with atypical ductal hyperplasia showed no neoplastic alteration following surgical biopsy. In our personal experience, core biopsy with Mammotome achieved a high diagnostic accuracy. CONCLUSIONS: After careful analysis of the results obtained using Mammotome in upright seated patients with stereotactic equipment, we can confirm the diagnostic accuracy of this procedure in mammography alterations not visible in sonography. In agreement with previous studies, we also confirm that the diagnostic accuracy of this approach, as well as possible complications deriving from it, do not depend on the position of the patient.