Role of ATP and related purines in inhibitory neurotransmission to the pig urinary bladder neck

Background and purpose:

As adenosine 5′-triphosphate (ATP) is one of the inhibitory mediators of the bladder outflow region, this study investigates the possible release of ATP or related purines in response to electrical field stimulation (EFS) and the purinoceptor(s) involved in nerve-mediated relaxations of the pig urinary bladder neck.

Experimental approach:

Urothelium-denuded and intact phenylephrine-precontracted strips were mounted in organ baths containing physiological saline solution at 37°C and gassed with 95% O₂ and 5% CO₂ for isometric force recordings.

Key results:

EFS, in the presence of atropine, guanethidine and N^G-nitro-L-arginine, and exogenous purines, produced frequency- and concentration-dependent relaxations respectively. Adenosine 5′-diphosphate (ADP) and adenosine were more potent than ATP in producing relaxation, while uridine 5′-triphosphate, uridine 5′-diphosphate and α,β-methylene ATP were less effective. The non-selective P2 antagonist suramin, and the P2Y₁ and P1 receptor blockers 2′-deoxy-N6-methyladenosine 3′,5′-bisphosphate tetrasodium and 8-(p-sulphophenyl)theophylline, respectively, inhibited the responses to EFS and ATP. The P1 agonist''s potency was: 5′-N-ethylcarboxamidoadenosine (NECA)>4-2[[6-amino-9-(N-ethyl-b-D-ribofuranuronamidosyl)-9H-purin-2-yl]amino]ethyl]benzene propanoic acid hydrochloride>2-chloro-N⁶-cyclopentyladenosine>-2-chloro-6-[[(3-iodophenyl)methyl]amino]-9H-purin-9-yl]-1-deoxy-N-methyl-b-D-ribofuranuronamide = adenosine. 4-(-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl) phenol, an A_2A antagonist, reduced the relaxations to EFS, adenosine and NECA. In urothelium-intact samples, relaxations to EFS and purines were smaller than in urothelium-denuded preparations. Neuronal voltage-gated Na⁺ channels blockade failed to modify ATP relaxations. At basal tension, EFS- and ATP-induced contractions were resistant to desensitization or blockade of P2X₁ and P2X₃ receptors.

Conclusions and implications:

ATP is involved in the non-adrenergic, non-cholinergic, non-nitrergic inhibitory neurotransmission in the pig bladder neck, producing relaxation largely through muscle A_2A receptors after breakdown to adenosine, and P2Y₁ receptors after breakdown to ADP. Antagonists of these receptors may be useful for urinary incontinence treatment produced by intrinsic sphincteric deficiency.     

Direct identification of Yersinia enterocolitica in blood by polymerase chain reaction amplification

Primers based on the nucleotide sequence of the virF gene in the pYV plasmid and the chromosomal ail gene were used in polymerase chain reaction (PCR) amplifications to directly identify Yersinia enterocolitica in blood. Approximately 500 bacteria seeded into 100 microL of blood can be extracted and amplified by PCR to yield positive results. PCR analyses of seven Y. enterocolitica isolates previously implicated in blood contaminations showed that only one isolate harbored the plasmid-borne virF gene; however, all seven isolates were identified effectively by the PCR product amplified from the chromosomal gene. The PCR assay has the potential for use in the identification of Y. enterocolitica contamination in stored units of blood or in the rapid diagnosis of transfusion-related bacteremia caused by Y.     

Retroperitoneal sarcomas: A review of disease spectrum,radiological features,characterisation and management

Retroperitoneal sarcomas are a rare disease. The overall 5‐year survival rate for these lesions remains low, and surgical management offers the only option for effective treatment and potential for cure. Radiotherapy is increasingly being employed in addition to standard surgical treatment. Improvements in cross‐sectional imaging have also facilitated better characterisation of lesions, preoperative planning and long‐term follow‐up. This article reviews the current literature and documents the various types of retroperitoneal sarcomas with a particular approach to their imaging features. We also highlight the pathology, diagnostic methods and most current management of these tumours.     

Joining the dots: a plea for precise estimates of the maternal mortality ratio in sub-Saharan Africa

Monitoring of maternal mortality levels in sub-Saharan Africa (SSA) to assess the achievements of safe motherhood programmes and for MDG-5 has been made difficult because of the lack of precise estimates of the maternal mortality ratio (MMR). Projections based on the slow rate of decline of the MMR indicate that MDG-5 may not be reached before the end of this century in this region. Measurements done using demographical and health surveys, statistical modelling and censuses are imprecise and do not allow trends in individual countries to be established. SSA countries should be encouraged to measure mortality levels from their own resources, using methods that produce precise estimates such as population-based surveys. Establishment of the trends will lead to country-specific program targets. The less frequent but more precise measurements can be afforded by SSA countries, as a case study from Zimbabwe shows.     

Development of hatching blastocysts from immature human oocytes following in-vitro maturation and fertilization using a co-culture system

Recently, in-vitro maturation (IVM) of immature human oocytes recovered from non-stimulated follicles has been applied in the treatment of infertility. However, in previous reports, very few embryos cultured in conventional medium have reached the expanded blastocyst stage following in-vitro maturation and fertilization (IVM/IVF). The objective of this study was to investigate whether the developmental competence of human embryos following IVM/IVF could be enhanced by the use of a human ampullary cell co-culture system. Immature human oocytes were aspirated from small follicles at Caesarean section and then cultured in medium containing human menopausal gonadotrophin for 36 to 48 h, followed by insemination. Zygotes were randomly cultured either in conventional culture medium alone or in the co-culture system. Of 48 embryos cultured in conventional medium alone, all arrested at the 2-16- cell stage on day 3 after insemination. Of 46 embryos cultured in the co-culture system, 26 embryos (56.5%) arrested at the 2-16-cell stage. Six embryos (13%) developed to the morula stage. Fourteen embryos (30.4%) developed to expanded blastocysts and two blastocysts were hatching on day 7 after insemination. We conclude that co-culture significantly enhances the development of blastocysts in embryos resulting from IVM/IVF.      

Treatment of Allergic Bronchopulmonary Aspergillosis with Fluconazole and Itraconazole

Treatment of allergic bronchopulmonary aspergillosis (ABPA) has remained both problematic as well as controversial. Although the sheet anchor in treatment of ABPA still remains steroids, various workers have tried oral antifungals (fluconazole and itraconazole) with encouraging results. This study evaluates the effect of fluconazole or itraconazole in the treatment of ABPA patients and compares them with the patients who had received palliative therapy other than antifungals. Case records of 44 proven cases of ABPA treated at our referral service hospital during February 1998 to April 2001 were analyzed. In addition to oral and inhaled bronchodilators, 16 patients received fluconazole 150 mg OD and 13 patients itraconazole 200 mg OD for six months. Response to therapy was assessed clinically, radiologically and by spirometry every 3 months. Patients who did not receive antifungals had chronic course characterized by airway obstruction, recurrent pulmonary consolidation and obstructive defect on pulmonary function test (PFT). Patients treated with itraconazole had better control of asthma symptoms, less requirement of reliever inhalers, steroids and lesser exacerbations of asthma during follow-up even after stopping antifungal. Fluconazole group had better control of symptoms but improvement in other parameters was not statistically significant. From this study it was evident that itraconazole improved the symptoms of airway obstruction, pulmonary functions, pulmonary opacities and decreased exacerbations during follow up.Key Words: Allergic bronchopulmonary aspergillosis, Fluconazole, Itraconazole     

The biochemical and clinical consequences of 2'-deoxycoformycin in refractory lymphoproliferative malignancy

A deficiency of adenosine deaminase, an enzyme important in purine nucleoside catabolism, is associated with a severe combined immunodeficiency disease in children. Inhibition of this enzyme in vitro and in vivo results in an impairment in lymphoblast proliferation. We have investigated the pharmacologic inhibition of this enzyme by 2'-deoxycoformycin in 15 patients with hematologic malignancies. Biochemical consequences of the administration of this agent were closely monitored in erythrocytes, nucleated peripheral blood and bone marrow cells, serum, and urine. A marked rise in erythrocyte dATP was accompanied by a depletion of ATP in those patients exhibiting toxicity. Most patients excreted large amounts of deoxyadenosine but not adenosine in the urine. Serum deoxyadenosine rose in patients demonstrating a marked decrease in cell mass. The biochemical disturbances and clinical toxicity, including hepatic, renal, and conjunctival abnormalities, were usually reversible. Central nervous system toxicity, which potentially was the most serious consequence, was associated with high erythrocyte dATP/ATP ratios and high levels of cerebrospinal fluid deoxyadenosine. In patients with lymphoma and leukemia, objective responses were observed but were short- lived. Patients with chronic lymphocytic leukemia receiving weekly low doses of the drug demonstrated minimal toxicity and some efficacy. The chemotherapeutic potential o 2'-deoxycoformycin, as either a single agent or in combination with Ara-A, merits further exploration.