Platelet-derived growth factor (PDGF) and PDGF receptors in rat corpus cavernosum: changes in expression after transient in vivo hypoxia

Platelet-derived growth factor (PDGF) overactivity has been implicated in atherosclerosis and several fibrotic conditions including lung and kidney fibrosis, liver cirrhosis and myelofibrosis. Low oxygen tension (hypoxia) is a known stimulus for transcriptional induction of PDGF ligand and receptor genes in different tissues. We studied the expression and localization of PDGF-A, PDGF-B, and PDGF receptor (PDGFR)-alpha and -beta subunits in adult rat isolated corpus cavernosum (CC) under generalized transient hypoxia (pO(2) 10%) in comparison with normoxic conditions. Semi-quantitative RT-PCR analysis of mRNA extracted from rat penis showed higher amounts of PDGF-A, PDGF-B and PDGFR-beta mRNA transcripts in hypoxic versus normoxic animals. The immunohistochemical analysis showed that the localization of PDGF subunits and PDGFR-beta was confined to the cytoplasm of the perivascular smooth muscle cells, endothelium and trabecular fibroblasts. Our findings indicate that transient low oxygen tension induces PDGF overexpression in rat CC, which in the long term may lead to an increase of connective tissue production. We suggest that a local impairment of the PDGF/PDGFR system may contribute to CC fibrosis, which is an established cause of erectile dysfunction in man.

Activation of rho GTPases by cytotoxic necrotizing factor 1 induces macropinocytosis and scavenging activity in epithelial cells

Macropinocytosis, a ruffling-driven process that allows the capture of large material, is an essential aspect of normal cell function. It can be either constitutive, as in professional phagocytes where it ends with the digestion of captured material, or induced, as in epithelial cells stimulated by growth factors. In this case, the internalized material recycles back to the cell surface. We herein show that activation of Rho GTPases by a bacterial protein toxin, the Escherichia coli cytotoxic necrotizing factor 1 (CNF1), allowed epithelial cells to engulf and digest apoptotic cells in a manner similar to that of professional phagocytes. In particular, we have demonstrated that 1) the activation of all Rho, Rac, and Cdc42 by CNF1 was essential for the capture and internalization of apoptotic cells; and 2) such activation allowed the discharge of macropinosomal content into Rab7 and lysosomal associated membrane protein-1 acidic lysosomal vesicles where the ingested particles underwent degradation. Taken together, these findings indicate that CNF1-induced "switching on" of Rho GTPases may induce in epithelial cells a scavenging activity, comparable to that exerted by professional phagocytes. The activation of such activity in epithelial cells may be relevant, in mucosal tissues, in supporting or integrating the scavenging activity of resident macrophages.

An Escherichia coli cytotoxin increases superoxide anion generation via rac in epithelial cells

Cytotoxic Necrotizing Factor 1 (CNF1) is a protein toxin from Escherichia coli that induces the activation of Rho, Rac, and Cdc42 GTPases, all involved in actin reorganization. Rac plays a further role in oxidase function. In epithelial cells, CNF1 has been reported to induce a phagocytic-like behavior in terms of a ruffle-driven ingestion of large material. We herein show that CNF1-activated epithelial cells may exert additional cell responses typical of professional phagocytes following stimulation, i.e., an increase in oxygen consumption and the generation of superoxide anions. Such effects were triggered by the contact of latex beads with epithelial cells and were significantly augmented by CNF1-induced Rac activation. Altogether our data indicate that Rac, one of the targets of CNF1, plays a pivotal role in these phenomena, suggesting the involvement in epithelial cells of a Rac-dependent NADPH-oxidase complex similar to that employed by professional phagocytes.

The release of leptin and its effect on hormone release from human pituitary adenomas

BACKGROUND

Leptin is the protein product of the obese gene, known to play an important role in body energy balance. The leptin receptor exists in numerous isoforms, the long isoform being the major form involved in signal transduction. Leptin expression has recently been demonstrated in the human pituitary, both in normal tissue and in pituitary adenomas. The long isoform of the leptin receptor has also been shown to be present in pituitary adenomas; however, contrasting results have been obtained regarding its expression in the normal human pituitary.

AIM

The aim of this study was (i) to investigate the presence and pattern of distribution of leptin mRNA and the long isoform of its receptor mRNA in the normal pituitary and in different types of pituitary adenomas with RT-PCR; (ii) to study leptin secretion from human pituitary tumours in culture and (iii) to assess in vitro pituitary hormone release following stimulation with human leptin.

RESULTS

Leptin receptor long isoform expression was detected in 2/4 GH-secreting adenomas, 12/17 non-functioning adenomas, 5/9 ACTH-secreting adenomas, 1/2 prolactinomas, 2/2 FSH-secreting adenomas and 5/5 normal pituitaries. The receptor long isoform did not segregate with any particular tumour type, and varying levels of expression were detected between the tissues studied. Leptin mRNA was detected at a low level of expression in 2/7 GH-secreting adenomas, 9/14 non-functioning adenomas, 2/3 ACTH-secreting adenomas, 1/3 prolactinomas and 1/3 FSH-secreting adenomas. We were unable to detect leptin mRNA in any of the five normal pituitaries removed at autopsy; however, immunostaining of a non-tumorous pituitary adjacent to an adenoma removed at transsphenoidal surgery showed scattered leptin positive cells. Culture of pituitary adenomas showed that 16/47 released leptin into the incubation media. Leptin release did not correlate with tumour type or with any of the other pituitary hormones released. In vitro leptin stimulation of pituitary tumours caused stimulation of FSH and alpha-subunit secretion from a non-functioning adenoma and TSH secretion from a somatotroph adenoma.

CONCLUSION

We conclude that not only is leptin stored within the pituitary, but it may also be released from pituitary cells and modulate other pituitary hormone secretion. Pituitary leptin may therefore be a novel paracrine regulator of pituitary function.

Subjective visual halos after sildenafil (Viagra) administration: Electroretinographic evaluation

PURPOSE

The ophthalmologic and electroretinographic (ERG) findings in one subject with subjective visual disturbances after sildenafil administration are described.

DESIGN

Interventional case report.

METHODS

A complete ophthalmologic examination was performed, including best-corrected visual acuity and ERG, repeated 1 and 2 hours after administration of 100 mg of sildenafil.

MAIN OUTCOME MEASURES

Rod responses were obtained over a range of retinal illuminances from those producing a minimum detectable response to those producing rod saturation. Intensity amplitude function was determined.

RESULTS

At 2 hours after 100 mg of oral sildenafil, we observed significant variations from baseline in parameters of best-fit Naka-Rushton function; V(max) was notably higher, and K was 0.14 log units lower than baseline.

CONCLUSIONS

Sildenafil administration resulted in a higher rod response to light stimuli and in a higher rod sensitivity. These findings are consistent with the weak PDE-6 inhibition induced by sildenafil.

Blood alcohol concentration and management of road trauma patients in the emergency department

BACKGROUND

The effects of blood alcohol on injury after crash are controversial, and safe limits are not settled. We examined if a positive blood alcohol concentration, even in a nontoxic range, affects management and outcome of injured patients after road crashes.

METHODS

In this prospective cohort study, we recruited all adult subjects admitted to an emergency department within 4 hours after a road crash. Outcomes were mortality or expected permanent disability, and data related to patients' management.

RESULTS

Alcohol-positive trauma patients were more frequently critical at admission (odds ratio [OR], 1.89; 95% confidence interval [CI], 1.18-3.02), and had an increased risk of combined mortality or expected permanent disability (OR, 1.67; 95% CI, 1.08-2.58), need for intensive care (OR, 1.87; 95% CI, 1.01-3.46), surgery (OR, 1.91; 95% CI, 1.37-2.66) and blood transfusions (OR, 2.09; 95% CI, 1.20-3.64), and acute medical complications (OR, 1.94; 95% CI, 1.33-2.85). All these events were explained by higher trauma severity. Only the risk of unsuspected injuries, diagnosed only at final evaluation, was independently associated with a positive blood alcohol concentration (OR, 4.98; 95% CI, 3.62-6.87), in addition to trauma severity and preexisting chronic conditions. Blood alcohol measurement significantly improved the accuracy in predicting unsuspected injuries, from 81.3% to 86.2%.

CONCLUSION

In injured patients after a road crash, a positive blood alcohol concentration increases the chance that the final diagnosis will include more injuries than initially documented. More careful monitoring is needed in alcohol-positive trauma patients, independent of clinical status, injury severity, and overt symptoms of alcohol intoxication.

Leptin in reproduction

In mammals, the function of the reproductive system is dependent on the availability of energy in the environment. It is well established that acute modifications of energy balance modulate the hypothalamic-pituitary-gonadal axis. In several species, fasting and caloric restriction have been shown to cause the suppression of pulsatile luteinizing hormone secretion, via an inhibition of the gonadotropin-releasing hormone pulse generator. Such a mechanism probably prevents energy being wasted for reproduction. By contrast, excessive energy storage and obesity interfere with the correct regulation of the reproductive axis. The identification of leptin and leptin receptors, along with studies performed in animal models of leptin deficiency and resistance, has focused attention on the role of this molecule in reproduction, and disclosed new aspects of the relationship between energy stores, adipose tissue and reproductive function. Here, we discuss the central and peripheral effects of leptin on reproductive tissues, and try to fit a complex reality into a simplified model. In particular, the roles of leptin in reproduction at different anatomical levels and in various clinical and experimental settings are discussed.

Systemic leukocyte filtration during cardiopulmonary bypass

Cardiopulmonary bypass (CPB) induces a whole body inflammatory response leading to postoperative lung dysfunction. Activated leukocytes may play a role in the pathogenesis of pulmonary dysfunction. We evaluated postoperative lung function after the use of leukocyte-depleting filters incorporated in the extracorporeal circuit during CPB. From November 1997 to March 2000, 40 patients underwent isolated coronary artery bypass grafting. Patients were randomly allocated to the leukocyte-depletion group (group F, 20 patients) or to the control group (group C, 20 patients). There was no significant difference between the two groups with respect to age, sex, weight, height, body surface area, haemoglobin and haematocrit levels, preoperative left ventricular ejection fraction, cooling temperature, aortic crossclamping and CBP duration. Blood samples were drawn preoperatively, at aortic declamping, 60 min after CPB, after arriving at the intensive care unit (ICU) and 24 h after the operation. We analysed blood cell count, elastase, interleukin-8 (IL-8) and tumour necrosis factor (TNF-alpha) levels and continuous monitoring of arterial blood gases in the intensive care unit (ICU). The analysis of total circulating white blood cells (WBCs) showed a significant reduction of WBCs in both groups soon after aortic declamping [from the right atrium: 6.4 x 10(9)/l +/- 1.4 x 10(9)/l in group F vs 10.3 +/- 1.8 x 10(9)/l in group C (p<0.05); from the left atrium: 5.8 +/- 1.3 x 10(9)/l in group F vs 8.4 +/- 1.9 x 10(9)/l in group C (p<0.05)] and after 60 min of CPB [7.1 +/- 2.2 x 10(9)/l in group F vs 10.4 +/- 1.8 x 10(9)/l in group C (p<0.05)]. The analysis of circulating neutrophils showed similar findings in both groups. Elastase levels increased during CPB in both groups with a peak at the end of CPB without significant difference between the two groups (group C: 260 +/- 148 microg/l vs group F: 371 +/- 68 microg/l). The decrease of plasmatic elestase levels was observed, for both groups, in the 24 h after CPB. There was no difference in intubation time between the two groups (16.4 h for group C vs 11.2 h for group F). Pulmonary function tested by pulmonary respiratory index [RI = partial pressure of oxygen/fraction of inspired oxygen (PaO2/FiO2 x 100)] did not show significant difference between the two groups, either arriving in the ICU (group C RI 265 vs group F RI 322), or after 3 h (group RI 304 vs group F RI 305) or after 6 h (group C RI 292 vs group F RI 319). Leukocyte-depleting filters reduce with blood cells count during CPB, but, in this study, WBC depletion did not significantly improve clinical conditions or laboratory finding.

Androgens and penile erection: evidence for a direct relationship between free testosterone and cavernous vasodilation in men with erectile dysfunction

OBJECTIVE

Androgens are essential in the maintenance of nitric oxide-mediated erectile activity in the rat. The objective of the present study was to investigate the role of androgens in regulating trabecular smooth muscle relaxation in the corpus cavernosum in response to vasoactive challenge in men with erectile dysfunction (ED).

DESIGN

Retrospective, double-blind correlation analyses.

PATIENTS

Fifty-two impotent patients without confounding risk factors for ED were obtained from a total of 250 undergoing diagnostic evaluation.

MEASUREMENTS

All patients had dynamic colour duplex ultrasound (D-CDU) and hormonal evaluation for LH, total and free testosterone, SHBG and oestradiol.

RESULTS

Based upon D-CDU results patients were diagnosed as having arteriogenic (AR, n = 18; mean age 51) or corporeal venocclusive (CVO, n = 13; mean age 49) ED; in other patients (n = 21, mean age 43) a diagnosis of psychogenic (P)-ED was made by comprehensive psychogenic testing and confirmed by normal D-CDU results. AR and CVO patients had altered compliance of cavernous arteries recorded by D-CDU [20-25% lower resistive index (RI) than patients with psychogenic ED], and lower free testosterone (FT) levels than psychogenic patients [42.3 +/-3.5 SE and 49.3+/-5.2 vs. 75.2+/-7.6 pmol/l, respectively; P<0.01]. More important, in all patients there was a strong direct correlation between resistive index values and FT levels (r = 0.47, P = 0.002); the relationship was maintained also when adjusted for age, SHBG and oestradiol (r = 0.37, P = 0.02).

CONCLUSIONS

These results indicate that in men with erectile dysfunction low free testosterone may correlate independently of age with the impaired relaxation of cavernous endothelial and corporeal smooth muscle cells to a vasoactive challenge. These findings give clinical support to the experimental knowledge of the importance of androgens in regulating smooth muscle function in the penis.

Evaporation of near-extremal Reissner-Nordström black holes

The formation of near-extremal Reissner-Nordström black holes in the S-wave approximation can be described, near the event horizon, by an effective solvable model. The corresponding one-loop quantum theory remains solvable and allows one to follow analytically the evaporation process, which is shown to require an infinite amount of time.

Responses of the skin microcirculation to acetylcholine in patients with essential hypertension and in normotensive patients with chronic renal failure

AIMS

To assess the endothelial function of the skin microcirculation in chronic renal failure (CRF) independent of hypertension, we investigated the changes of the cutaneous blood flow induced by iontophoretic delivery of acetylcholine (ACh) and of sodium nitroprusside (SNP) in CRF patients free from arterial hypertension and in patients with essential hypertension.

METHODS

The study included 20 patients affected by CRF (mean creatinine clearance 12+/-2 ml/min) without arterial hypertension (mean blood pressure 96+/-1 mm Hg), 15 patients affected by essential hypertension (mean blood pressure 124 +/-1 mm Hg), and 20 normal controls. The changes of skin blood flow following iontophoretic delivery of ACh and of SNP were measured by laser Doppler flowmetry.

RESULTS

Following maximal ACh or SNP delivery, the change of blood flow from the baseline was similar both in normals (683+/-92 vs. 684 +/- 87%) and in CRF patients (778+/-108 vs. 803+/-124%), whereas in the hypertensives the response to ACh was lower than to SNP (434+/-48 vs. 702 +/- 98%, p<0.01). Since the third ACh delivery dose, the skin blood flow increments were significantly lower in the hypertensive than in the CRF or in the normal control groups, whereas no difference was observed between uremics and controls.

CONCLUSIONS

The endothelium-dependent hyperemia following ACh iontophoretic delivery is impaired in the skin microcirculation of essential hypertensive patients, but this is not the case in CRF patients with no history of arterial hypertension. This suggests that CRF per se, independent of arterial hypertension, is not associated with endothelial dysfunction of skin microcirculation.

Management of fever in neutropenic patients with acute leukemia: current role of ceftazidime plus amikacin as empiric therapy

To evaluate the current role of ceftazidime plus amikacin as empiric therapy in the management of fever in neutropenic patients with acute leukemia, we examined 172 febrile episodes in 106 patients enrolled during 1996-98. The overall success rate (survival of neutropenia, both with and without protocol modification) was 90%: 39% without modification and 51% with modification. We documented a significant difference in documented infections (DI) and fever of undetermined origin (FUO): success without modification was lower in DI and higher in FUO. Failure (death due to documented or presumed infection) was recorded in 10% of all episodes. Episodes with severe neutropenia were treated in 48% of cases without modification and in 41% with modification. No significant difference was observed in the status of underlying disease. 33% of gram-negative bacteria responsible for bloodstream infections were resistant to ceftazidime, of which 21% were multiresistant strains. We conclude that initial chemotherapy with ceftazidime plus amikacin remains a reasonable option for treating febrile and prolonged neutropenia, although patients with DI are likely to require additional or modified treatment. The emergence of resistant strains is an increasingly important issue.

Analysis of SYT-SSX fusion transcripts and bcl-2 expression and phosphorylation status in synovial sarcoma

Synovial sarcomas (SS) are characterized by a chromosomal translocation t(X;18)(p11.2;q11.2) which usually fuses the SYT gene from chromosome 18 to SSX1 or SSX2 genes on chromosome X. Also, a variant SYT-SSX4 fusion gene has recently been shown in a single SS case. In addition to these cytogenetic changes, bcl-2 expression, as assessed by immunohistochemistry, has been reported to be an almost general constitutive alteration of SS. In the present work, we analyze a series of 36 SS surgical samples (from 34 patients) by RT-PCR for the presence of the SYT-SSX1 or the SYT-SSX2 fusion transcript. The analysis was extended to SYT-SSX4 on SYT-SSX1-negative and SYT-SSX2-negative cases only. Our results showed a significant correlation between the SYT-SSX2 fusion and the monophasic SS histologic subtype. SYT-SSX1 fusion transcripts were present in both monophasic and biphasic tumors. The SYT-SSX4 fusion type was detected in a single monophasic SS. In the same series of SS cases, we also confirmed and extended the previously reported constitutive expression of bcl-2 protein, by using both immunohistochemical and western blot analysis. Moreover, we demonstrated that the BCL-2 gene is not rearranged or amplified at genomic level, indicating that the high levels of bcl-2 expression observed in SS might result from transcriptional activation of the gene and/or protein stabilization. Finally, we show that bcl-2 is not phosphorylated in tumors from patients who had been preoperatively treated with radio/chemotherapy, in tumors from untreated patients, or in an SS cell line (CME-1) after in vitro treatment with cytotoxic concentrations of DNA-damaging agents or taxanes. These data indicate that SS cells are unable to activate an apoptosis pathway involving bcl-2 phosphorylation/inactivation and may provide a possible explanation for the limited effectiveness of conventional pharmacological treatments of this tumor type.

Enterotoxicity and cytotoxicity of Vibrio parahaemolyticus thermostable direct hemolysin in in vitro systems

Vibrio parahaemolyticus is a marine bacterium known to be a common cause of seafood gastroenteritis worldwide. The thermostable direct hemolysin (TDH) has been proposed to be a major virulence factor of V. parahaemolyticus. TDH causes intestinal fluid secretion as well as cytotoxicity in a variety of cell types. In this study, we investigated the interplay between the hemolysin's enterotoxic and cytotoxic effects by using both human and rat cell monolayers. As revealed by microspectrofluorimetry, the toxin causes a dose-dependent increase in intracellular free calcium in both Caco-2 and IEC-6 cells. This effect was reversible only when low toxin concentrations were tested. The TDH-activated ion influx pathway is not selective for calcium but admits ions such sodium and manganese as well. Furthermore, in the same range of concentration, the hemolysin triggers a calcium-dependent chloride secretion. At high concentrations, TDH induces a dose-dependent but calcium-independent cell death as assessed by functional, biochemical, and morphological assays.

Basal metabolic rate in anorexia nervosa: relation to body composition and leptin concentrations

BACKGROUND

Leptin is thought to represent a peripheral signal involved in the regulation of energy balance. Its action has been studied in animals and obese subjects. Little is known about leptin's role during negative energy balance.

OBJECTIVE

The objective was to evaluate the relation between energy turnover, body composition, and plasma leptin concentrations in anorexia nervosa (AN).

DESIGN

Sixteen weight-stable women with AN were compared with 22 control subjects and 14 rehabilitated AN patients (R-AN). Basal metabolic rate (BMR) was measured by indirect calorimetry; fat-free mass (FFM) and fat mass (FM) were calculated according to a 4-compartment model. Plasma leptin was determined by radioimmunoassay.

RESULTS

The BMR of AN patients (2.73 +/- 0.37 kJ/min) was significantly lower than that of control subjects (3.45 +/- 0.34 kJ/min) (P < 0.001), even after adjustment for FFM (2.92 +/- 0.33 kJ/min in AN patients and 3.30 +/- 0.26 kJ/min in control subjects; P < 0.004). Plasma leptin concentrations in AN patients were 76% lower than in control subjects, even after body fat was controlled for. In R-AN patients, BMR was not significantly different from that of control subjects and leptin concentrations were generally close to normal. Plasma leptin concentrations correlated significantly with FM (r(2) = 0.53, P < 0.0000) and BMR, even after adjustment for FFM (r(2) = 0.21, P < 0.0003).

CONCLUSIONS

BMR and plasma leptin concentrations are depressed in patients with AN; this is not explained by body-composition changes. The relation between leptin and BMR suggests that leptin plays a role in the energy sparing response to exposure to chronic energy deficiency. The return of BMR to normal and the significant increase in leptin concentrations in R-AN patients suggests a full reversibility of this adaptation mechanism.

Leptin and aging: correlation with endocrine changes in male and female healthy adult populations of different body weights

Aging is associated with changes in plasma levels of several hormones. There are conflicting reports on whether circulating leptin levels change during aging, the possible explanation for which is that alterations in adiposity and body mass index (BMI) also occur. In this study we measured plasma leptin and other hormonal parameters known to influence leptin in 150 men and 320 women of a wide age (18-77 yr) and BMI (18.5-61.1 kg/m2) range. Subjects of each gender were separated into 2 groups of similar BMI, i.e. nonobese (BMI, <30) and obese (BMI, >30), and treated separately. Statistical analysis was performed, treating each group of subjects as a whole population or divided into age groups (<30, 30-50, and >50 yr). BMI-adjusted leptin levels were progressively lower with increasing age in women, with a consistent fall after menopause (-21%; P < 0.001); in men, leptin levels also tended to be lower in subjects more than 50 yr of age, but the reduction was not significant. Multiple linear regression analysis, performed on subjects treated either as a whole population or divided into obese and nonobese, showed that in both genders BMI and age were independent contributors of leptin levels, and there was an inverse relationship between leptin and age in both obese (standardized coefficient beta = -0.25 in women and -0.23 in men; P < 0.01) and nonobese (-0.22 in women and -0.20 in men; P < 0.05) subjects. The correlation of leptin and age with plasma levels of sex and thyroid hormones, GH, insulin-like growth factor I, PRL, and insulin was also evaluated. The variables that correlated with leptin were included in a multiple regression model that included BMI and age. Testosterone in men (-0.43 in nonobese and -0.19 in obese; P < 0.05) and estradiol in women (0.22 in nonobese and 0.24 in obese; P < 0.05) were important contributors to leptin levels; also, dehydroepiandrosterone sulfate in obese women (-0.16) and sex hormone-binding globulin in obese subjects of both genders (0.15 in women and 0.19 in men) were significant determinants in the model. However, none of the hormonal parameters abolished the negative correlation between leptin and age or the gender difference in leptin levels. In conclusion, our data show that in adult humans of different body weight, serum leptin gradually declines during aging; leptin reduction is higher in women than in men, but it is independent from BMI and other age-related endocrine changes.

Amifostine in the treatment of low-risk myelodysplastic syndromes

BACKGROUND AND OBJECTIVE

The phosphorylated aminothiol agent amifostine (Ethyol) protects bone marrow and other tissues from toxicity due to ionizing radiation and antineoplastic drugs, and stimulates progenitors from normal and myelodysplastic bone marrow. Contrasting results have been published so far on the effectiveness of amifostine in correcting cytopenia in patients with myelodysplastic syndromes (MDS).

DESIGN AND METHODS

In a pilot phase II study we treated 26 patients with low risk MDS (13 RA, 2 RARS, 2 CMML, 9 RAEB with blasts < 10%) with amifostine (200 mg/m(2 )x 3/week for 4 weeks).

RESULTS

Hemoglobin concentration, reticulocyte, neutrophil and platelet counts increased respectively in 6 (23%), 11 (42%), 13 (50%) and 9 (34%) of patients. Red cell transfusions were reduced (> 50%) in 4/26 patients and abolished in 1/26. Unexpectedly a significant decrease in soluble transferrin receptor level at week 4 of therapy, compared to the basal level (p<0.04), was observed in the whole population of patients.

INTERPRETATION AND CONCLUSIONS

Amifostine can ameliorate cytopenia in some patients with MDS, with few and mild side effects. Neutropenia is more likely to be corrected than anemia or thrombocytopenia. Mechanisms underlying this biological effect remain to be clarified.

Pituitary adenylate cyclase-activating polypeptide (PACAP) and PACAP-receptor type 1 expression in rat and human placenta

Pituitary adenylate cyclase-activating polypeptide (PACAP), the new hypophysiotropic factor member of the vasoactive intestinal peptide (VIP)/secretin/glucagon/GHRH family of neuropeptides, exerts its biological action by interacting with both PACAP-selective type I receptors (PAC1) and type II receptors (VPAC1), which bind both PACAP and VIP. The placenta is a site of production of hypophysiotropic factors that participate in the control of local hormone production, as well as the respective hypothalamic-pituitary neurohormones. In the present study, we show the expression of PACAP gene and irPACAP distribution within rat and human placental tissues, by means of RT-PCR and immunohystochemical experiments. In both rat and human placenta, we evaluated the expression of PAC1 gene by Northern hybridization analysis performed with a 32P-labeled 706 nt complementary DNA probe, derived from the full-length coding region of the rPAC1 complementary DNA. The results of these experiments demonstrate the presence, in both human and rat placenta, of a 7.5-kb transcript similar in size to those detected in the ovary, brain, and hypothalamus. Alternative splicing of two exons occurs in human and rat PAC1 gene generating splice variants with variable tissue-specific expression. To ascertain which of the splice variants were expressed in placental tissue we performed RT-nested PCR using primers flanking the insertion sequence termed hip/hop cassette in rat or SV1/SV2 box in human gene. Electrophoretic analysis of the PCR products showed a different pattern of expression of messenger RNA splicing variants in human and rat placenta. In particular, the rat placenta expresses the short PAC1 receptor (PAC1short), the rPAC1-hip or hop (which are indistinguishable with the primers used), and the rPAC1-hip-hop, whereas the human placenta expresses only the PAC1SV1 (or SV2) variant, structurally homologous to the rat PAC1 hip (or hop). Sequence analysis of the human PCR-amplified PAC1 variant was therefore carried out and revealed that human placenta only expresses the PAC1SV2 isoform. The presence and characterization of PACAP binding sites was then investigated in human placenta by radioligand binding studies performed on crude membrane preparation using [125I]PACAP27 as tracer. Scatchard analysis of the binding results revealed the presence of two binding sites, one with high affinity and low capacity (Kd 0.33+/-0.04 nM; Bmax 36.9+/-12.1 fmol/mg protein) and one with low affinity and high capacity (Kd 24+/-6.9 nM, Bmax 9.3+/-0.19 pmol/mg protein). The relative potencies of PACAP-related peptides for inhibition ofradioligand binding were: PACAP27 > or = PACAP38 > VIP, whereas GHRH and other unrelated peptides, such as CRH and beta-endorphin, did not inhibit [125I]PACAP27 binding. In conclusion, in this study, we provide evidence for the expression of PACAP within rat and human placenta. We also demonstrate that both human and rat placenta express the PAC1 gene and that the human tissue has binding sites for PACAP. These findings may suggest a role for PACAP in the regulation of placental physiology through autocrine and/or paracrine mechanisms.

Re-dosing of prostaglandin-E1 versus prostaglandin-E1 plus phentolamine in male erectile dysfunction: a dynamic color power Doppler study

During penile pharmacotesting, anxiety may overcome complete smooth muscle relaxation and lead to false positive diagnosis of organic male erectile dysfunction (ED). We tested the efficacy and safety of re-dosing of PGE1 alone versus combination of PGE, and the alpha1,2-blocker phentolamine (PHE) to improve an incomplete pharmaco-induced erection during color-power-Doppler (CPD) sonography. 116 consecutive impotent patients were submitted to CPD and injected with 10 microg PGE, plus audiovisual sexual stimulation. Clinical evaluation of rigidity and CPD parameters were normal in 26 patients while in the remaining they were upgraded in 15% and 35% after redosing of 10 microg PGE1 alone and 10 microg PGE1 plus 1 mg PHE, respectively (P < 0.05); furthermore, in these latter patients CPD studies showed increased visualisation of distal ramifications of helicine arterioles. The final diagnosis was changed in those patients who responded to re-dosing with no differences in the occurrence of prolonged erections between the two treatments. We conclude that re-dosing of PGE1/PHE mixture is a safe and effective procedure to maximize erectile response during dynamic CPD sonography and has a better diagnostic sensitivity than re-dosing of PGE1 alone.

Cryopreservation of white poplar (Populus alba L.) by vitrification of in vitro-grown shoot tips

 Shoot tips from in vitro-grown, cold-hardened stock plants of white poplar (Populus alba L.) were successfully cryopreserved at -196  °C by one-step vitrification. After preculturing at 5  °C for 2 days on hormone-free MS medium containing different sucrose concentrations, and loading for 20 min with 2 M glycerol and 0.4 M sucrose, shoot tips were treated with the PVS2 vitrification solution and plunged directly into liquid nitrogen. Best survival rate (90%) was obtained when shoot tips were precultured on 0.09 M sucrose, hormone-free MS medium, vitrified by exposure to PVS2 solution for 60 min at 0  °C and, following cryopreservation, rewarmed at 40  °C and washed in 1.2 M sucrose solution for 20 min. Regrowth was improved by plating shoot tips on a gelled MS medium containing 1.5 μM N⁶-benzyladenine plus 0.5 μM gibberellic acid, while shoot rooting was achieved on MS medium containing 3 μM indole-3-butyric acid. Following this procedure, almost 60% rooted shoots were obtained from cryopreserved shoot tips.

Effects of sildenafil (Viagra) administration on seminal parameters and post-ejaculatory refractory time in normal males

Sildenafil is a specific inhibitor of phosphodiesterase (PDE) type 5 and represents a powerful therapy for male erectile dysfunction (ED) of different aetiology. Recently, sildenafil has been shown to restore erections in temporary ED related to the need of semen collection for assisted reproductive techniques. In this study, we investigated whether sildenafil administration modifies seminal parameters and/or erectile function in normal healthy volunteers. In a double-blind, randomized, placebo-controlled, cross-over two period investigation we enrolled 20 healthy male volunteers (mean +/- SE age 32 +/- 0.5 years). Subjects were not using any medication for the 3 month period prior to the study and were engaged in a stable relationship with proven fertility. The effects of sildenafil (100 mg) on seminal parameters and erectile function after audiovisual sexual stimulation were evaluated by semen analysis and by colour-Duplex ultrasound (the Resistive Index) respectively. In all subjects, sildenafil caused no changes in seminal and erection parameters when compared to placebo. Interestingly, sildenafil administration led to a marked reduction of the post-ejaculatory refractory time (10.8 +/- 0.9 min versus 2.6 +/- 0.7 min for placebo and sildenafil respectively; P < 0.0001). These results indicate that in normal subjects acute sildenafil treatment does not modify semen characteristics and has a positive influence over the resumption of erections following ejaculation in the presence of a continuous erotic stimulus.