Identification, localization and functional in vitro and in vivo activity of oxytocin receptor in the rat penis

We recently found that the oxytocin receptor (OTR) is expressed in the human and rabbit corpus cavernosum and mediates contractility in vitro. The present study extended our investigations to the rat, and explored whether OTR regulates penile detumescence in vivo. Real-time RT-PCR quantitatively characterized the distribution of OTR mRNA in the male genital tract. Specific transcripts for OTR were expressed in all the tissues investigated. Penile expression of OTR was comparable to that observed in testis and prostate. Western blot analysis detected a single band of the expected molecular mass for OTR in all tissues examined, including rat penis. Expression of OTR protein in rat penile extracts was further confirmed by binding studies, using the OTR selective radiolabeled ligand 125I-OTA (K(d) = 17 +/- 6.5 pM, B(max)=15.7 +/- 5 fmoles/mg protein). OTR was immunolocalized to the endothelial and smooth muscle compartments of cavernous spaces and blood vessels. In rat corpus cavernosum strips, oxytocin (OT) and an OTR selective agonist ([Thr4,Gly7]OT) induced identical increases in tension, while different vasopressin agonists were less active. In vivo, OT intra-cavernous injection (ICI) dose-dependently inhibited intracavernous pressure (ICP) increase elicited by either electrical stimulation of the cavernous nerve or ICI of papaverine with similar IC(50)s (117.7 +/- 37 mU). The OTR antagonist, atosiban, counteracted the contractile effect of OT both in vitro and in vivo. Atosiban alone significantly increased ICP at lower stimulation frequencies (2 Hz = P<0.001 and 4 Hz = P<0.05 vs control), but not at the maximal frequency (16 Hz). Our data showed that OTR is present in the rat penis and mediates contractility both in vitro and in vivo, therefore suggesting a role for OT in maintaining penile detumescence.

Expression and functional activity of phosphodiesterase type 5 in human and rabbit vas deferens

The molecular mechanisms underlying the regulation of vas deferens (VD) motility and semen emission are still poorly understood. We now report evidence on VD expression of phosphodiesterase type 5 (PDE5), which regulates nitric oxide (NO)-induced relaxation and cGMP breakdown in smooth muscle cells. In human VD, the PDE5 abundance was relatively high (>3 x 10(6) molecules/microg total RNA), although 10-fold lower than in corpora cavernosa (CC). Also cGMP metabolising activity was higher in CC than in VD. However, both tissues share the same sensitivity to a broad panel of cGMP-related PDE inhibitors: sildenafil, tadalafil, dipyridamole, zaprinast, vinpocetine, EHNA and cilostamide. Based on the rank order of potency of these PDE inhibitors, we found that the cGMP metabolizing activity in human VD mostly corresponds to PDE5. PDE5 was immunolocalized in all the muscular layers of human and rabbit VD and was found to be negatively involved in regulating NO-induced relaxation. In addition, by using a rabbit model of hypogonadotropic hypogonadism, we found that PDE5 gene expression and activity are androgen-dependent in VD, as previously demonstrated in CC. In fact, the sensitivity to a NO-donor (NCX4040), its enhancement by PDE5 inhibitors and the PDE5-related cGMP breakdown were all affected by androgen manipulation. Our results provide a hypothesis explaining the beneficial effects of PDE inhibitors in patients with rapid ejaculation.

Effects of extremely low frequency electromagnetic fields on the adenylate kinase activity of rod outer segment of bovine retina

Extremely low frequency electromagnetic fields (ELF-EMFs) of 75 Hz with amplitudes above a threshold of about 125 microT have a dramatic effect on the adenylate kinase (AK) activity of the rod outer segment (ROS) membranes. In fact, the ATP production by ROS membranes or by purified disk membranes placed in the field decreased by approximately 54%. The decrease in enzymatic activity was independent of the time of exposure to the field and was completely reversible. When disk membranes were solubilized with Triton or a soluble isoform of AK was used, negligible effects of the field were obtained on the enzymatic activity, suggesting that the membrane has an important role in determining the conditions for the enzyme inactivation.

Case report: colonic manometry reveals abnormal propulsive behaviour after anterior resection of the rectum

Anterior resection of the rectum is a frequent surgical procedure. However, abnormal bowel habits following this procedure are frequently reported. The functional evaluation of these patients is usually limited to the anorectal area. By means of colonic manometry, we have evaluated a patient with frequent urge for defecation and increased bowel frequency following anterior resection of the rectum with straight coloanal anastomosis and almost normal anorectal function. Analysis of the tracing revealed a reduction of contractile segmental activity and much more high-amplitude propagated contractions than which occur in healthy subjects. These high-amplitude propagated contractions, representing the manometric equivalent of mass movements, were always in association with urge for defecation and, sometimes, with loose stools. High-amplitude simultaneous contractions were also observed. We feel that the surgical resection of a potential physiological brake may be responsible for these observations.

Electromagnetic field of extremely low frequency decreased adenylate kinase activity in retinal rod outer segment membranes

Adenylate kinase activity in rod outer segment membranes of bovine retina decreased of about 55% when exposed to an extremely low frequency electromagnetic field of 75 Hz and 250 microT. The effect was independent of the time of permanence in the field. Negligible effects of the field were found on the enzymatic activity of a soluble isoform of adenylate kinase or of rod outer segment membranes solubilized with Triton, suggesting the importance of the membrane in determining the conditions of the enzyme inactivation.

Biofeedback for pelvic floor dysfunction in constipation

Pelvic floor dyssynergia is one of the commonest subtypes of constipation, and the conventional treatment (dietary fibre and laxatives) is often unsatisfactory. Recently biofeedback training has been introduced as an alternative treatment. The authors review the evidence for this approach and conclude that, although controlled studies are few and open to criticism, about two thirds of patients with pelvic floor dyssynergia should benefit from biofeedback training

Laparoscopic transduodenal papillosphincteroplasty

In the past 20 years, the approach to biliary lithiasis has changed tremendously as a result of advances in endoscopic and laparoscopic techniques. The two most important open surgical techniques involve extraction of the stones from the common bile duct combined with choledochoenterostomy and papillotomy followed by transduodenal papillosphinteroplasty. Ideally, the choledochotomy is followed by the insertion of a T-tube in the common bile duct. The transcystic approach has never been considered. The first endoscopic papillotomy was performed in 1973. Subsequently, it became the most widely used method for removal of common bile duct stones. In this report we explore the possibility of performing a laparoscopic transduodenal papillosphincteroplasty, following the strict rules commonly used in surgery. After cholecystectomy, a Fogarty catheter, is introduced through the cystic duct. This is followed by a minimal duodenotomy, then incision of the papillar sphincter. In this surgical proposal, we do not intend to substitute technique, but this method should be considered the ultimate solution in the laparoscopic approach to cholecystic choledocholithiasis.

Symptomatic reversible duodenal compression due to iatrogenic retroperitoneal hematoma

Selective serotonin reuptake inhibitors are frequently employed to treat depression. However, although rarely, coagulation abnormalities have been described following the use of these compounds, and these effects appear to be enhanced by simultaneous use of nonsteroidal anti-inflammatory drugs. We describe a case of reversible symptomatic duodenal compression caused by a retroperitoneal hematoma after ingestion of sertraline and nimesulide.

[Posterior mediastinum neoplasms: a case of schwannoma]

The Authors report the case of a 33-year-old male affected with an asymptomatic schwannoma of the posterior mediastinum, and review the relevant Literature, discussing the difficulties in making the differential diagnosis of the posterior mediastinum lesions, particularly in the pre-clinical phase. Neurogenic tumors represent about 75 percent of all tumors of mediastinum and about one third of all tumors of the mediastinum. They can originate from the peripheral nervous system group, from the sympathetic nervous system group or, in rare cases, from the vagus nerve. In adult patients, they are usually found by chance during radiographic examination of the thorax, and they are usually asymptomatic and benign. During preoperative evaluation, a magnetic resonance examination of rachis should be done to exclude the possibility of intraspinal involvement. If there are no contraindications, the treatment of choice should be surgical resection by means of thoracoscopy or thoracotomy, when size and location of the tumors allow it in order to prevent malignant evolution.

Effects of hypoxia on endothelin-1 sensitivity in the corpus cavernosum

The penis remains in a hypo-oxygenated, flaccid state for a large majority of the time. In this study, we investigated the effect of changing oxygen tension on the expression and functional activity of endothelin-1 (ET-1) receptors in the penis. Experiments were performed in rabbit and human corpora cavernosa (CC) as well as in human fetal penile tissue and cell cultures [human fetal penile endothelial cells (hfPECs) and human fetal smooth muscle cells (hfPSMCs)]. Endothelin A (ETA) receptors are expressed by both endothelial and muscular cells in all tissues investigated. Only penile endothelial cells express endothelin B (ETB) receptors, which are further turned on during experimental hypoxia. In addition, hypoxia also allows ETB expression in the muscular compartment without affecting ETA expression. This hypoxia-induced over-expression of ETB decreased the contractile activity of ET-1 and increased ETB-mediated relaxation. The latter was essentially related to increased ETB-mediated nitric oxide formation in hfPEC and even in hfPSMC. Hypoxia also induced a time-dependent down-regulation of RhoA and Rho kinase (ROK) expression which, in turn, participated in the decreased contractile activity of ET-1 in the hypoxic penile tissue. Accordingly, during hypoxia, an ROK inhibitor, Y27632, was less effective in relaxing ET-1-precontracted strips. In conclusion, prolonged (24 h) hypoxia stimulated several counter-regulatory mechanisms in penile tissue, including up-regulation of ETB and down-regulation of RhoA/ROK pathways, which may help to preserve CC hypo-oxygenation, allowing smooth muscle relaxation and, most probably, penile erection.

Parasitological and immunological effects induced by immunization of Mandrillus sphinx against the human filarial Loa loa using infective stage larvae irradiated at 40 Krad

Six mandrills were immunized with 150 Loa loa infective stage larvae (L3) irradiated with 40 Krad, and challenged with 100 L3, 60 days after initial vaccination. The parasitological outcome of this immunization was compared to results from six mandrills infected with normal L3. No clear association was seen between vaccination and microfilaremia until day 245 when a significant drop in the level of microfilaria occurred in vaccinated compared to infected animals (5 vs 10 mf/ml; p = 0.012). A one-year follow-up of the humoral immune response showed a strong adult, microfilariae (Mf) and L3 specific IgG response, with distinct profiles for each extract. In immunized animal a significant decrease in antibody level was systematically observed between days 90-145 for the anti-L3 and anti-adult IgG. However, in the same group anti-Mf antibody levels that peaked around 160-175 days post-challenge, were inversely correlated with the decrease in Mf density between day 200 and day 386. These results suggest that immunization with irradiated L3 using these specific conditions may affect the appearance of Mf.

Are colonic regular contractile frequency patterns in slow transit constipation a relevant pathophysiological phenomenon?

BACKGROUND

Pathogenesis of slow transit constipation still remains elusive. Some studies have shown several colonic motor abnormalities; however, it is not easy to understand the relative importance of the single ones.

AIMS

Since it has been hypothesized that an excess of periodic distal motor activity may be of pathophysiological importance in patients with slow transit constipation, we evaluated regular colonic contractile frequencies in a homogeneous cohort of these patients.

PATIENTS

A total of 26 female patients (age range 34 to 67 years) fulfilling the Rome II criteria for constipation entered the study. No patient had evidence of secondary forms of constipation and distal obstruction.

METHODS

Twenty-four hour colonic manometric studies were obtained for each patient. Regular contractile patterns (with frequencies ranging from 2 to 8 cycles/min) were calculated for the entire recording period and in single colonic segments.

RESULTS

Overall, regular patterns accounted for about 3% of the total colonic motor activity (average 30 min/day per subject), with the 3 cycles/min being the predominant contractile rhythm. Most of this activity was present in the sigmoid colon, accounting for >50% of the total amount of motility, and it was more prevalent than in the descending and transverse colon; no differences were revealed in the descending with respect to the transverse colon. No daily fluctuations of regular contractile activity, nor a cyclic pattern, nor migration between recording points were observed.

CONCLUSIONS

Regular colonic frequency patterns are probably of minor pathophysiological importance in slow transit constipation, even in the light of the scant amount of such phenomena previously documented in healthy subjects.

Nitric oxide and portal hypertension: a nitric oxide-releasing derivative of ursodeoxycholic acid that selectively releases nitric oxide in the liver

Portal hypertension, a common consequence of chronic liver diseases, is directly responsible for most complications of cirrhosis. In liver microcirculation, nitric oxide is considered a major fine tuner of vascular tone by counterbalancing vasoconstrictors (sympathetic nervous activity, the renin-angiotensin system, and endothelin-1) in normal and cirrhotic livers. The deficiency of endothelial nitric oxide release is a key factor in the hemodynamic abnormalities associated with the dynamic component of portal hypertension. Conventional nitric oxide donors release nitric oxide into the blood stream, causing systemic hypotension and progression of vasodilatory syndrome in cirrhotic patients. NCX1000 is a nitric oxide-releasing derivative of ursodeoxycholic acid-derived compounds, being capable of selectively releasing nitric oxide into the liver circulation. Administration of NCX1000 to portal hypertensive rats decreases intrahepatic resistance providing a novel therapy for the treatment of portal hypertension.

[Atrial fibrillation and hyperthyroidism: results after thyroidectomy]

Hyperthyroidism patients can develop atrial fibrillation (AF) with a frequency range between 10 and 25%. The Authors consider 256 hyperthyroid patients operated in their Department, from 1985 to 2001. Before and after surgery, thyroid examination, routine blood tests and common diagnostic evaluations were performed. The follow-up has been 12 months and during this period a L-Thyroxine (50-200 mg/die) therapy has been arranged. Before surgery 59 patients (23%) showed an AF associated with palpitations (76%), asthenia (66%), tremors (54%) and dyspnea (43%). The onset of AF was less than 1 months in 18% of cases, less than 3 months in 30% and chronic in remaining 52%. The 87% of patients was already pharmacologically treated. All the patients were treated with anticoagulants, with a INR value between 2 and 3. After the surgery, 47% of patients presented a restoration of the sinusal rhythm, while the 53% showed a stronger therapeutic responsiveness to specific antiarrhythmic therapy. Treatment of FA hyperthyroid patients with FA tends to normalize the function of the thyroid gland (euthyroidism). In our experience the restoring of sinusal rhythm usually develops in patients with 50 years of age (45 +/- 5 years), while in older patients AF tends to be resistant to treatment.

Equation of state data for iron at pressures beyond 10 Mbar

We present equation of state points for iron, in the pressure range 10-45 Mbar, the first obtained with laser-driven shock waves. The experiment has been performed with the high energy laser Phebus, optically smoothed with Kinoform phase plates. Our results double the set of existing experimental data at very high pressures showing good agreement with the predictions of the quotidian equation of state model and with previous results.

[Neurinoma of the brachial plexus: 2 case reports]

Neurinomas, also referred to as neurilemmomas and schwannomas, are rare benign tumours of the peripheral nerves. A small percentage of these lesions arise from the brachial plexus. The Authors report two cases of schwannoma arising from the brachial plexus. Such lesions, usually asymptomatic, may cause sensitivity alterations or, less frequently, motor deficits in the involved arm. Tumour enucleation, avoiding damage to any of the nervous fascicles, is the treatment of choice.

Castleman's disease: an unusual cause of mediastinal mass and anemia

We reported a case of thoracic localized, mixed variant, Castleman's Disease (angiofollicular lymph node hyperplasia) with a favourable clinical course presenting with mediastinal mass, microcytic anemia, mild thrombocytosis, polyclonal hyper-gammaglobulinaemia and without symptoms. Castleman's Disease must be always considered in the differential diagnosis of solitary mediastinal masses. Transthoracic fine needle aspiration cytology is usually nondiagnostic; in fact, cytologically, Castleman's Disease can be confused with other mediastinal lymphoproliferative disorders (such as thymomas or lymphomas). The optimal therapeutic approach is unknown but a complete surgical resection is treatment of choice for localized disease.

Nitric oxide-releasing NSAIDs: a review of their current status

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most widely prescribed drugs worldwide owing to their anti-inflammatory, antipyretic and analgesic properties. However, their use is hampered by gastrointestinal (GI) toxicity, the most common drug-related serious adverse event in industrialised nations. Nitric oxide (NO)-releasing NSAIDs, a recently described class of drugs, are generated by adding a nitroxybutyl or a nitrosothiol moiety to the parent NSAID via a short-chain ester linkage. While efficacy of nitrosothiol-NO-NSAIDs still awaits investigation, nitroxybutyl-NO-NSAIDs have been extensively studied in animals, thus the abbreviation NO-NSAIDs used here refers to the latter group of NSAID derivatives. NO-NSAIDs retain the anti-inflammatory and antipyretic activity of original NSAIDs, although they exhibit markedly reduced gastrointestinal toxicity. NO-NSAIDs are nonselective cyclo-oxygenase (COX) inhibitors, and they also exert COX-independent activities that are NO-dependent. Indeed, NO-NSAIDs suppress production of the cytokines interleukin (IL)-1beta, IL-18 and interferon-gamma by causing the S-nitrosilation/inhibition of caspase-1. In acute and chronic animal models of inflammation, it has been demonstrated that NO-NSAIDs abrogated prostaglandin E2 as well as thromboxane B2 generation. In a murine model, NO-naproxen was approximately 10-fold more potent than naproxen in reducing animal writhing after intraperitoneal injection of acetic acid. Similar data have been obtained in chronic models of pain such as rat adjuvant arthritis. In vivo and in vitro studies suggest that NO-aspirin (acetylsalicylic acid) exerts more potent antithrombotic action than aspirin, probably by coupling the ability to inhibit COX-1 with the anti-adhesive effect of NO. Moreover, in a model of renal injury NO-flurbiprofen not only has been demonstrated to be devoid of nephrotoxicity but also to ameliorate renal function. Finally, in an animal model of chronic neurodegenerative disease, NO-flurbiprofen and NO-aspirin attenuated the brain inflammatory response. The GI toxicity of NO-flurbiprofen and NO-naproxen is currently being investigated in healthy individuals.

Effect of acute and chronic levosulpiride administration on gastric tone and perception in functional dyspepsia

BACKGROUND

Altered visceral perception is common in functional dyspepsia (FD). Dopaminergic pathways control gastrointestinal motility, but whether they modulate visceral sensitivity is unknown.

AIM

To investigate whether levosulpiride, a D2 antagonist, modulates gastric sensitivity and compliance in dyspeptic patients.

METHODS

Eight healthy subjects and 16 dyspeptic patients underwent graded gastric distensions using a tensostat. In dyspeptic patients the same isotonic distensions were repeated during either levosulpiride or saline administration. Eight FD patients were evaluated after 4-week treatment with oral levosulpiride. Gastrointestinal symptoms were evaluated using a 100 mm visual analogue score. Perception was scored on a scale of 0 to 6.

RESULTS

Although healthy subjects and FD patients had similar gastric compliance, FD patients tolerated lower tension levels. At the same distending tension levels, levosulpiride decreased gastric compliance and perception score (14 +/- 6% and 38 +/- 10% change, respectively; P < 0.05 vs. saline) only in FD patients. Isotonic distensions exhibited very reproducible perception. Chronic levosulpiride administration significantly reduced dyspeptic symptoms and increased discomfort threshold.

CONCLUSIONS

Compared with healthy subjects, FD patients show marked gastric hypersensitivity. In FD patients levosulpiride decreased the perception of gastric distension with an action unrelated to change of gastric tone. Chronic levosulpiride administration significantly ameliorates gastrointestinal symptoms and increases the discomfort threshold.

ATP synthesis in the disk membranes of rod outer segments of bovine retina

ATP is synthesized on the disk membrane isolated from rod outer segments of the bovine retina. Together with a slow component which accounted for a constant rate of about 22 nmol ATP/min/mg of protein and which was due to the adenylate kinase activity, a fast component with a maximal activity of about 58 nmol ATP/min/mg of protein was measured at physiological calcium concentrations. This fast activity disappeared in the presence of the Ca(2+) ionophore A23187, was inhibited by vanadate or thapsigargin but not by oligomycin, suggesting that this ATP synthesis is due to the reversal functioning of the Ca(2+)-ATPase previously found on the disk membranes.