Late-onset and long-lasting neutropenias in the young: A new entity anticipating immune-dysregulation disorders.

This study identifies a new chronic form of immune neutropenia in the young with or without detectable indirect anti-neutrophil antibodies, characterized by mild/moderate neutropenia low risk of severe infection (14%), tendency to develop autoimmune phenomena over the course of the disease (cumulative incidence of 58.6% after 20 years of disease duration), leukopenia, progressive reduction of absolute lymphocyte count and a T- and B-cell profile similar to autoimmune disorders like Sjogren syndrome, rheumatoid arthritis, and systemic lupus erythematosus (increased HLADR+ and CD3 + TCRγδ cells, reduced T regulatory cells, increased double-negative B and a tendency to reduced B memory cells). In a minority of patients, P/LP variants related to primary immuno-regulatory disorders were found. This new form may fit the group of "Likely acquired neutropenia," a provisional category included in the recent International Guidelines on Diagnosis and Management of Neutropenia of EHA and EUNET INNOCHRON ACTION 18233. The early recognition of this form of neutropenia would help clinicians to delineate better specific monitoring plans, genetic counseling, and potentially targeted therapies.

From modeling to remodeling of upper airways: Centrality of hyaluronan (hyaluronic acid).

After traumatic events (accidental or surgical), the respiratory tract activates specific and prolix repairing mechanisms which tend to claw back the primitive differentiated state. The attempt of reactivation of the normal tissue functions is called 'remodeling' and its aim is to reinstate the modeling mechanisms that existed before the damaging event or the pathology's establishment. Endoscopic sinus surgery represents the gold standard treatment for inflammatory, malformative, benign, and, in selected cases, malignant diseases. The surgical technique is commonly described as minimally invasive as the nostrils are used as an access route and therefore does not leave any external scars. Currently, the surgical procedures, even though minimally invasive regarding the way in, are in fact widely destructive towards the surgical target. The healing process and re-epithelialization will depend on the amount of bony tissue that has been exposed and it will be important to stratify the different surgical typologies in order to foresee the increasing difficulty of mucosal healing process. As far as upper inflammatory diseases are concerned, recent studies demonstrated how intranasal hyaluronic acid can positively regulate mucosal glands secretion and modulate inflammatory response, being a useful tool for the improvement of remodeling after endoscopic sinus surgery. Acid has shown to be able to regulate mucosal glands secretion and modulate the inflammatory response.

Effects of sodium hyaluronate in children with recurrent upper respiratory tract infections: results of a randomised controlled study.

Hyaluronic acid is a major component of many extracellular matrices that plays a role in the regulation of vasomotor tone and mucous gland secretion, and in the modulation of the inflammatory process in upper and lower airways. This pilot study was aimed at evaluating the effects of nasal washes with 9 mg nebulised sodium hyaluronate given for 15 days per month over 3 months in 75 paediatric patients with recurrent upper respiratory tract infections (URTI). Eligible patients were randomized to treatment with nasal washes containing 9 mg sodium hyaluronate plus saline solution or saline alone, according to an open-label, parallel group design, with blind observer assessment. Ciliary motility, which was assessed based on a 0-3 point rating scale (0 = absent, 1 = less than 5 minutes, 2 = greater than or equal to 5 and ≤ 10 minutes, 3 = greater than 10 minutes) was the primary study endpoint. The secondary efficacy variables included cytological (presence of neutrophils, eosinophils and mast cells), microbiological (presence of bacteria and mycetes), endoscopical (presence of adenoid hypertrophy and biofilm) and clinical (presence of rhinitis, post-nasal drip, nasal dyspnoea) parameters. The two treatment groups (mean age 7.5 years, 53percent of males) were comparable for baseline data, except a higher mean age in the control group than in the treated group. Treatment with 9 mg sodium hyaluronate was associated with significantly greater improvements (p less than 0.001 between groups) in primary outcome ciliary motility [odds ratio (OR) 13.61; 95 percent CI 4.51-41.00 in the univariate regression analysis that examined the probability of improvement]. Treatment with 9 mg sodium hyaluronate was also significantly superior to saline alone in adenoid hypertrophy (p less than 0.001; OR 14.72; 95 percent CI 4.74-45.68), presence of bacteria (p = 0.026; OR 2.95; 95 percent CI 1.15-7.55), neutrophils (p = 0.002; OR 4.51; 95 percent CI 1.75-11.62), rhinitis (p = 0.040; OR 10.47; 95 percent CI 3.10-35.31), nasal dyspnoea (p = 0.047; OR 3.80; 95 percent CI 1.09-13.19) and biofilm (p = 0.049; OR 9.90; 95 percent CI 2.61-37.47). Advantages of 9 mg of sodium hyaluronate over control on post-nasal drip and presence of mycetes (although evident) did not reach the level of statistical significance. The superiority of the treated group over saline alone was confirmed in a multivariate logistic regression analysis that took into account age as confounding factor. The number of days of absence from school was significantly lower in the 9 mg sodium hyaluronate group compared to controls (p less than 0.001 between groups). A 3-month intermittent treatment with 9 mg sodium hyaluronate with nasal washes plus saline solution was associated with significant improvements in ciliary motility and in cytological, microbiological, endoscopic and clinical outcomes compared to saline, in children with recurrent URTI.

Hyaluronan plus saline nasal washes in the treatment of rhino-sinusal symptoms in patients undergoing functional endoscopic sinus surgery for rhino-sinusal remodeling.

Hyaluronic acid is a major component of many extracellular matrices and plays a central role in the homeostasis of physiology in upper and lower airways. When topically administered following endoscopic sinus surgery, hyaluronic acid may be effective in functional recovery and in the prevention of recurrence of chronic rhinosinusistis. This pilot study was aimed at evaluating the effects of nebulised 9 mg of sodium hyaluronate given for 15 days per months over 3 months in 46 patients aged greater than 4 years who underwent functional endoscopic sinus surgery (FESS) for rhino-sinusal remodelling. Eligible patients were randomized to receive nebulised 9 mg sodium hyaluronate nasal washes plus saline solution or 5 ml saline alone (23 patients in each group), according to an open-label, parallel group design, with blind observer assessment. Treatment was administered by means of a nasal ampoule that allows nebulisation of particles with a median aerodynamic diameter greater than 10 micron, i.e. suitable for upper respiratory airways deposition. The efficacy variables included clinical (presence of nasal dyspnoea), endoscopical (ostium of paranasal sinuses, oedema, respiratory patency, synechiae, and appearance of nasal mucosa) and cytological (ciliary motility and presence of neutrophils, eosinophils, mast cells, bacteria, mycetes and bio film) measures. At the end of the study, patients expressed an opinion on the overall tolerability of treatment. The two treatment groups were comparable at baseline. Treatment with 9 mg of sodium hyaluronate was associated with significantly greater improvements compared to controls in nasal dyspnoea (p less than 0.001), presence of mycetes (p = 0.044), ciliary motility (p less than 0.001) and abnormalities in nasal secretions. A univariate logistic model, in which the odd ratio (OR) indicates the probability of success in the 9 mg sodium hyaluronate group compared to the control group, showed that the highest OR was observed for presence of nasal dyspnoea (OR = 21.36; 95 percent CI: 1.07 to 426.56), normal mucosa at endoscopy (OR: 9.62; 95 percent CI: 1.82 to 50.89), ciliary motility (OR: 7.27; 95 percent CI: 1.68 to 31.42) and presence of bio film (OR: 4.41; 95 percent CI: 1.26 to 15.40). Treatment with 9 mg sodium hyaluronate plus saline was well tolerated. A 3-month intermittent treatment with 9 mg sodium hyaluronate plus saline solution nasal washes following FESS for rhino-sinusal remodelling was associated with significant improvements in nasal dyspnoea, appearance of nasal mucosa at endoscopy and ciliary motility compared to saline alone.

Recurrent acute rhinosinusitis: a single blind clinical study of N-acetylcysteine vs ambroxol associated to corticosteroid therapy.

The aim of rhinosinusitis treatment is to restore sinusal eutrophism and to normalize ventilation and mucociliary transport. Frequently the improvement of sinusal physiological conditions is associated with a reduction of infections and pulmonary symptoms. The treatment of these diseases often requires the combination of medical and surgical strategies. In particular, the aim of the medical therapy is multiple: to treat the infection (with antibiotics), to reduce the mucosal swelling (with corticosteroids) and to improve mucus drainage (with mucolytics or muco-regulators). The use of atomized nasal douche, as a washing of the nasal fossas, is chosen because of its local action minimizing systemic adverse effects. The surgical treatment is secondary to medical failure, and it is focused on clearing the sinusal ostia in the sphenoethmoidal recess and the osteomeatal complex. In case of recurrent sinonasal diseases the importance of the surgical operation is represented by the fact that the medical treatment better reaches the target in the sinusal space. This study is focused on the primary medical treatment of acute recurrent rhinosinusitis. The patients who immediately needed surgical treatment were excluded from the study (because of the presence of an anatomical obstruction of the osteomeatal complex and/or the sphenoethmoidal recess, hence non-susceptible to improvement by medical therapy alone), and these patients were immediately addressed to undergo a CT scan examination in order to be involved in a future surgical programme. The medical treatment for those forms which do not require antibiotics (i.e. when infections are not involved), is based on the use of topical corticosteroids. While there are controversies on the real efficacy of adding mucolytic agents to the steroids, they are commonly prescribed in clinical practice, with the rationale of reducing viscosity and improving clearance of mucus in order to help the restoration of the physiological sinus conditions. The primary aim of the medical treatment is to reduce the number of acute episodes and thus to increase the time between the exacerbations, allowing a good quality of life without necessitating surgical procedure.

Aerosol therapy with thiamphenicol glycinate: a retrospective study on efficacy and safety in a group of sixty-six oncological patients.

The purpose of this paper is to present the effectiveness of aerosol administration of TG in a group of oncological patients. Thiamphenicol is an antimicrobial agent active in the treatment of infection of different etiology and localisation due to its broad spectrum of antimicrobial activity as well as its pharmacokinetic properties. The data of the retrospective study analysis of the activity of TG, administered to oncological patients affected by infections of the respiratory tract, showed that TG administered alone or in association with other antibiotics was globally effective in more than 95% of patients. These positive results were obtained in immunologically compromised patients. The therapeutic advantages of using TG are: ease of use - aerosol therapy permits good local action; tolerability - no adverse reaction or intolerance; the possibility of using it in an ideal association with other antibiotics to combat the infectious pathology.

Dreaming experience as a useful diagnostic clue for syncopal episodes.

BACKGROUND: The differential diagnosis between epileptic seizures and syncopes is a common occurrence in clinical practice. The manifestations of seizure and syncope sometimes overlap, and available diagnostic testing often not provides a conclusive answer. Syncope is often preceded by a symptom complex characterized by lightheadedness, generalized muscle weakness, giddiness, visual blurring, tinnitus, and gastrointestinal symptoms. These subjective symptoms are very important in guiding the diagnosis. In our experience, the impression of coming out of a dream after the syncopal episode is a subjective symptom commonly reported by patients, if questioned. METHODS: To verify the occurrence of dreaming experience after syncope and after generalized tonic-clonic seizures (GTCS) and its diagnostic value in differential diagnosis, we asked 100 patients with GTCS and diagnosis of idiopathic generalized epilepsy (Group 1) and 100 patients with a certain diagnosis of syncope (Group 2) whether they have never felt the impression of coming out of a dream after the loss of consciousness (GTCS or syncope, respectively). RESULTS: In Group 1, nobody referred the dreaming experience, whereas in the syncope group, 19% of patients referred this subjective symptom. CONCLUSIONS: Dreaming experience seems to be an additional useful diagnostic clue for syncopal episodes, helping the clinician to differentiate them from seizures.

Heart rate and systolic blood pressure in patients with persistent atrial fibrillation. A linguistic analysis.

BACKGROUND: During atrial fibrillation (AF), ventricular response is highly irregular and thus the beat-to-beat variation of blood pressure is increased because of variations in filling time and in contractility. OBJECTIVES: Aim of the present study is to investigate the short-term dynamics of RR and SAP series in patients with AF, during rest and tilt, and after restoration of sinus rhythm. METHODS: We computed symbolic sequences of the three phases, as they retain important features of the dynamics generated by the underlying control system. Then we applied a method based on rank order statistics of symbolic sequences to investigate the profile of different types of dynamics. The linguistic distance (range 0-1) between sequences represents a measure of similarity to assess whether the different physiological states are reflected on the dynamics of RR and SAP series. RESULTS: The distance between rest and tilt phases is 0.06 ± 0.02 for RR series, meaning they are very similar, while it is 0.21 ± 0.13 for SAP series, showing a difference in the short-term dynamics. RR mean decreases during tilt (738 ± 164 vs. 692 ± 152 ms, p <0.05, rest vs. tilt), while mean SAP is not significantly different (101 ± 20 vs. 104 ± 14 mmHg, rest vs. tilt). Comparing AF and sinus rhythm, both RR and SAP series result different in terms of the computed distance. CONCLUSIONS: SAP short-term dynamics seem to significantly change when comparing rest and tilt phases, while RR series remain unchanged. Moreover, RR mean but not SAP series significantly decreases during tilt.

Viral-load and B-lymphocyte monitoring of EBV reactivation after allogeneic hemopoietic SCT in children.

EBV-associated post transplant lymphoproliferative disease (EBV-PTLD) is a life-threatening complication that may occur after hemopoietic SCT. We prospectively screened 80 children on a weekly basis using nested quantitative PCR to evaluate EBV genome copies. EBV viral load <1000 copies per 10(5) PBMC was observed in 63% of transplants, whereas it was between 1000 and 9999 copies per 10(5) PBMC in 13%, and between 10 000 and 19 999 in 10%, with no significant increase in percentage of CD20+ lymphocytes. Viral load reached > or = 20 000 copies per 10(5) PBMC in 14% of patients, and rituximab was administered to 75% of them. None of the patients except one developed a lymphoproliferative disease. Our study found that only 13% of unrelated donor HSCT recipients had a very high risk of EBV-PTLD defined as > or = 20 000 geq per 10(5) PBMC associated with an increase in CD20+ lymphocyte. We suggest that rituximab could be administered in the presence of very high levels of EBV-DNA viral load or in the presence of mid levels of EBV-DNA viral load associated with an increase in the percentage of CD20+ lymphocytes. Through this approach, we significantly reduced the number of patients treated with rituximab, and consequently the acute and chronic adverse events related to this treatment.

Daclizumab as useful treatment in refractory acute GVHD: a paediatric experience.

GVHD remains a serious complication after allogeneic SCT. We describe 13 paediatric patients treated with daclizumab for refractory acute GVHD (aGVHD). After 30 days of daclizumab administration, all patients with cutaneous aGVHD reached complete response. Among patients with gastrointestinal disease, 50 and 30% had complete and partial response, respectively, whereas 11 and 55% of patients with hepatic aGVHD achieved CR and PR, respectively. Overall, complete (46%) and partial (46%) responses were demonstrated in 92% of our patients, whereas the remaining patients (8%) were nonresponders. No life-threatening infectious episodes were recorded within 100 days from transplant in this selected group of paediatric patients. Overall 46% of patients were alive at a median of 461 days from SCT, but 50% of them developed chronic GVHD. In our experience, daclizumab proved to be a useful and safe treatment for refractory and steroid-resistant/dependent aGVHD, in particular for cutaneous and low-moderate intestinal involvement.

Phosphoinositide 3-OH kinase p85alpha and p110beta are essential for androgen receptor transactivation and tumor progression in prostate cancers.

Phosphoinositide 3-OH kinases (PI3Ks) are a group of major intracellular signaling molecules. In our previous study, we found that inhibition of PI3K activity suppressed the androgen receptor (AR)-mediated gene expression in prostate cancer cells. The AR has been considered as a critical determinant for the development and progression of human prostate cancers. In this study, we sought to identify the PI3K isoforms involved in AR transactivation. Using a gene-specific small interference RNA (siRNA) approach, we determined that the regulatory isoform p85alpha and the catalytic isoform p110beta, but not p110alpha, were required for androgen-stimulated AR transactivation and cell proliferation in prostate cancer cells. Consistently, overexpression of wild-type p110beta but not p110alpha gene led to androgen-independent AR transactivation. Silencing p110beta gene in prostate cancer cells abolished tumor growth in nude mice. Of the dual (lipid and protein) kinase activities, p110beta's lipid kinase activity was required for AR transactivation. Further analysis by a chromatin immunoprecipitation assay showed that p110beta is indispensable for androgen-induced AR-DNA interaction. Finally, gene expression analysis of clinical specimens showed that both p85alpha and p110beta were highly expressed in malignant prostate tissues compared to the nonmalignant compartments, and their expression levels correlated significantly with disease progression. Taken together, our data demonstrated that p85alpha and p110beta are essential for androgen-stimulated AR transactivation, and their aberrant expression or activation might play an important role in prostate cancer progression.

Serum/glucocorticoid-induced protein kinase-1 facilitates androgen receptor-dependent cell survival.

Androgen receptor (AR) is a critical factor in the development and progression of prostate cancer. We and others recently demonstrated that eliminating AR expression leads to apoptotic cell death in AR-positive prostate cancer cells. To understand the mechanisms of AR-dependent survival, we performed a genome-wide search for AR-regulated survival genes. We found that serum/glucocorticoid-induced protein kinase-1 (SGK-1) mRNA levels were significantly upregulated after androgen stimulation, which was confirmed to be AR dependent. Promoter analysis revealed that the AR interacted with the proximal and distal regions of the sgk1 promoter, leading to sgk-1 promoter activation after androgen stimulation. Functional assays demonstrated that SGK-1 was indispensable for the protective effect of androgens on cell death induced by serum starvation. SGK-1 overexpression not only rescued cells from AR small-interfering RNA (siRNA)-induced apoptosis, but also enhanced AR transactivation, even in the absence of androgen. Additionally, SGK-1 siRNA reduced AR transactivation, indicating a positive feedback effect of SGK-1 expression on AR-mediated gene expression and cellular survival. Taken together, our data suggest that SGK-1 is an androgen-regulated gene that plays a pivotal role in AR-dependent survival and gene expression.

Preservation of clonal heterogeneity of the Pneumocystis carinii-specific CD4 T cell repertoire in HIV infected, asymptomatic individuals.

The loss of CD4 lymphocytes in HIV disease associates with opportunistic infections. Since diverse CD4 T cell clones respond to an opportunistic pathogen, we asked whether CD4 depletion deletes selected clones in the repertoire (vertical depletion) or it affects all clones by reducing the cell number in each progeny without affecting the overall number of clones (horizontal depletion). Understanding this point may help explain the mode of CD4 depletion and the mode of immunoreconstitution after therapy. Therefore we examined the CD4 T cell repertoire specific for Pneumocystis carinii, a relevant opportunistic pathogen in AIDS, in HIV-infected, asymptomatic individuals. We identified two patients of 36 asymptomatics for lack of proliferation to P. carinii, suggesting selective depletion of specific CD4 cells. To investigate clonal heterogeneity of P. carinii-responsive CD4 lymphocytes, specific CD4 T cell lines were generated and studied by TCR BV gene family usage and CDR3 length analysis (spectratyping). Clonal heterogeneity was similar in antigen-specific CD4 lines generated from P. carinii non-responding HIV seropositives and from controls. Thus, despite undetectable response to the pathogen, residual specific cells probably prevent overt infection and, when expanded in vitro, exhibit a clonal diversity similar to normal controls. These findings suggest a horizontal, rather than vertical, depletion in these asymptomatic patients.

Potential role of activin A in follicular development during the second half of pregnancy in the golden hamster: utero-placental source of activin A.

Numerous antral follicles develop during the second half of pregnancy in the golden hamster. However, mechanisms regulating follicular development during this period are unknown. Because inhibin and activin are related to follicular development, these hormones were studied to gain insight into any potential roles in follicular development. Plasma inhibin A and B suddenly increased from day 8 of pregnancy, reached peak levels on day 10 and gradually declined to term. Plasma activin A gradually increased from day 8 to day 15 of pregnancy, and this was followed by an abrupt decrease at day one of lactation. Ovariectomy on day 12 of pregnancy rapidly reduced plasma inhibin A and B, but not activin A levels. Hysterectomy or placentectomy on day 12 of pregnancy caused an abrupt decrease in the levels of plasma activin A and FSH, but not inhibin A and B at 6 h after surgery. Hysterectomy also induced atresia of large antral follicles at 24 h after surgery. These results indicate that antral follicles are the main source of circulating inhibin A and B, whereas uteri and placentae are the main source of circulating activin A. These results suggest that increased levels of activin A may be involved in folliculogenesis in the ovary during the second half of pregnancy in the golden hamster.

Analysis of the antigen specific T cell repertoires in HIV infection.

In addition to HIV infection, several acquired immunodeficiencies lead to depletion of CD4 lymphocytes. These include immunosuppression resulting from high dose cancer chemotherapy or induced to control graft rejection, as well as in autoimmune diseases. The consequence of this depletion is an increased susceptibility to opportunistic infections or the inability to control primary infection in the case of HIV infection. In all instances a full or partial immunoreconstitution is desirable. In order to monitor the cellular immune state of a patient, rational information cannot be simply derived from phenotypic quantification of T lymphocytes. Instead loss or recovery of CD4 cells should be monitored by defining the specificity, the function and the clonality of the relevant cell population. Several methods are now available for this type of investigation. Here we describe an approach for the definition of clonal heterogeneity of antigen specific CD4 lymphocytes, a parameter that may help monitor loss or reconstitution in acquired immunodeficiencies. As examples of antigen specific CD4 T cell responses we focused on Pneumocystis carinii and on cytomegalovirus, as prototypic opportunistic pathogens which are responsible for severe infections in AIDS and in other immunosuppressive conditions which arise for instance following transplantation. Specific CD4 T cell lines were generated from normal controls and from seropositives in order to select antigen specific lymphocytes. The cells were subsequently analyzed for clonal diversity according to TCR BV gene family usage and according to TCR CDR3 size heterogeneity (spectratyping).

The effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on weight gain and hepatic ethoxyresorufin-o-deethylase (EROD) induction vary with ovarian hormonal status in the immature gonadotropin-primed rat model.

Immature female rats received 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) during an induced proestrus or diestrus. The inhibitory effect of TCDD on acute weight gain and the induction of hepatic ethoxyresorufin-o-deethylase (EROD) activity by TCDD were greatest during proestrus. In a second experiment, ovariectomized rats received estradiol cypionate (ECP) or progesterone followed by TCDD. TCDD and estradiol each alone significantly inhibited weight gain. Progesterone potentiated the effects of TCDD on weight gain. The highest dose of ECP was associated with greater induction of hepatic EROD activity by TCDD than seen with TCDD alone. Estradiol modulates the induction of hepatic EROD activity by TCDD. Differential effects of TCDD on acute weight gain during proestrus vs. diestrus in this model do not mimic changes induced by estrogen alone. Hepatic responses to TCDD may vary according to phase of the female reproductive cycle.

Impaired ovulation by 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD) in immature rats treated with equine chorionic gonadotropin.

Several studies have established that 2,3,7,8 tetrachloro-p-dioxin (TCDD) blocks ovulation. The main purpose of this study was to determine if induced ovulation was delayed temporarily by TCDD. The ovulation model used was that of the gonadotropin-primed intact or hypophysectomized rat. Immature intact female Sprague-Dawley rats (IIR) were given 32 microg TCDD/kg by gavage on day 24 of age. The next day equine chorionic gonadotropin (eCG) (5 IU) was injected sc to stimulate follicular development. The number of ova in the oviducts, the ovulation rate, and steroid concentrations were determined at 72, 96, 120, and 144 h after eCG. Immature female Sprague-Dawley rats (IHR) were hypophysectomized on day 23 of age. On day 26, the IHR were given 20 microg TCDD/kg by gavage. The next day eCG (10 IU) was injected sc to stimulate follicle development and at 52 h after eCG, 10 IU human chorionic gonadotropin (hCG) was given to induce ovulation. The same parameters as in IIR were determined in IHR at 72, 96, and 120 h after eCG. TCDD decreased body and ovarian weight gains in both IIR and IHR. In IIR, TCDD delayed ovulation by 24 to 48 h reducing the number of ova shed as well as the number of animals ovulating at 72 and 96 h after eCG. In IHR, however, TCDD reduced only the number of ova shed but caused no delay in ovulation. The IIR treated with TCDD had low levels of progesterone (P4) at 72 and 96 h after eCG but high levels of estradiol (E2) at the same time points. This sustained high level of E2 production coincided with a transient decrease in serum concentrations of androstenedione (A4). The alteration of steroid hormones by TCDD was restored to normal by 48 h after ovulation in IIR. Serum P4 concentration was not altered by TCDD in IHR at 72 h after eCG but was decreased thereafter. The delay in ovulation induced by TCDD in IIR indicates the disruption of the hypothalamus-pituitary-ovary axis during proestrus. The decrease in number of ova shed in IHR induced by exogenous gonadotropins indicates an additional direct ovarian effect of TCDD in blocking ovulation.

A review of mechanisms controlling ovulation with implications for the anovulatory effects of polychlorinated dibenzo-p-dioxins in rodents.

Polychlorinated dibenzo-p-dioxins (PCDDs) can impinge on female fertility by preventing ovulation. In this review, the aspects of normal ovulatory physiology most relevant to our current understanding of PCDD action on the ovary are briefly reviewed. This is followed by a comprehensive assessment of data relevant to the effects of PCDDs during ovulation in the rat. PCDDs interrupt ovulation through direct effects on the ovary in combination with dysfunction of the hypothalamo-hypophyseal axis.

2,3,7,8-tetrachlorodibenzo-p-dioxin decreases responsiveness of the hypothalamus to estradiol as a feedback inducer of preovulatory gonadotropin secretion in the immature gonadotropin-primed rat.

Sprague-Dawley rats (23-day-old) were dosed with TCDD (32 microg/kg) in corn oil or vehicle alone. Equine chorionic gonadotropin (eCG) was injected (5 IU, sc) 24 h later to induce follicular development. Another 24 h later, half of TCDD- or corn oil-treated rats were injected (sc) with 17 beta-estradiol-cypionate (ECP, at 0.004 to 0.5 mg/kg). Blood and ovaries were collected on expected proestrous (preovulatory period) at 51, 54, and 58 h after eCG injection as well as in the morning after ovulation (72 h after eCG). Serum concentrations of 17 beta-estradiol (E), progesterone (P), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were determined by radioimmunoassay. The number of ova shed was measured at 72 h after injection of eCG by irrigating ova from oviducts. During the preovulatory period (approximately 58 h after eCG injection), a circulating level of 70-100 pg E/ml coincided with LH and FSH surges and later normal ovulation of 10 to 12 ova/rat was observed in controls. However, the same concentration of E was not associated with LH and FSH surges in rats treated with TCDD (32 microg/kg), resulting in reduced ovarian weight gain and reduction of ovulation by 70 to 80% (2-3 ova/rat). Blockage of the gonadotropin surge, reduced ovarian weight gain, and ovulation were all reversed completely by the lowest effective dose of ECP (0.1 mg/kg). At 72 h after eCG, serum P secretion was reduced and serum E levels were significantly increased compared to those of corn oil-treated controls. ECP alone had no effect on serum P levels at any time point, but in rats treated with TCDD and ECP, both the reduction of P (at 58 and 72 h) and the increase in E secretion (72 h) were completely reversed. Further studies confirmed that restoration by ECP of gonadotropin surges and associated ovulation could not be attained until circulating levels of E rose sufficiently high to trigger the LH and FSH surges. The new action threshold of E for inducing gonadotropin surges in rats treated with TCDD (32 microg/kg) was determined to be eight- to 10-fold higher than that in controls. Thus, it is apparent that TCDD decreased the responsiveness of the hypothalamus to E as a feedback inducer of preovulatory gonadotropin secretion.