Genetic identification of Anisakis spp. (Nematoda: Anisakidae) from cetaceans of the Southwestern Atlantic Ocean: ecological and zoogeographical implications.

Adult Anisakis Dujardin, 1845 were found in two specimens of killer whale Orcinus orca and one specimen of franciscana Pontoporia blainvillei stranded from off the coast of Buenos Aires Province, Argentina. Genetic identification of the nematodes (N = 144) was performed by sequence analysis of the mitochondrial (mtDNA cox2) and the nuclear (nas 10 nDNA) gene loci. Anisakis pegreffii and Anisakis berlandi were detected in the two individuals of O. orca, while Anisakis typica and A. pegreffii were identified in P. blainvillei. Morphological and morphometric analysis also carried out on adult specimens of A. pegreffii and A. berlandi has allowed to underlining the usefulness of genetic/molecular markers in their recognition. This represents the first record of A. pegreffii in O. orca and P. blainvillei and of A. berlandi in O. orca. This is also the first sympatric and syntopic occurrence, as adults, of A. pegreffii and A. berlandi from the Austral Region of the Atlantic Ocean waters. These results provide insights into the knowledge of the host ranges and geographical distribution of these parasites in the basin waters of the region. Pontoporia blainvillei showed low abundance values of infection with Anisakis spp., which is the general pattern for coastal dolphins in the area, whereas O. orca harboured higher abundance of Anisakis spp. than those previously recorded among cetacean species in the Argentine Sea. Differences in the Anisakis spp. distribution and their parasitic loads, observed among the three host specimens, are discussed in relation to the oceanographic parameters, as well as to the host ecology. The usefulness of genetic/molecular markers in the recognition of adults of the sibling species A. pegreffii and A. berlandi with considerable overlapping in morphometric and morphological characters was underlined. The distribution of Anisakis species from Southwestern Atlantic waters is discussed in relation to their value as indicators for studies on the zoogeography of their hosts at a regional-scale level.

Are different parasite guilds of Pagrus pagrus equally suitable sources of information on host zoogeography?

Metazoan parasite assemblages of Pagrus pagrus inhabiting the southwestern Atlantic were analysed with the aim of identifying the existence of different stocks and to comparatively assess the value of different parasite guilds as indicators of zoogeographical regions. A total of 186 fish was examined. Samples were obtained from three Brazilian and one Argentine localities, distributed in three different biogeographic districts of the Argentine Zoogeographical Province. Pagrus pagrus harboured 26 metazoan parasite species distributed in three guilds, ectoparasites (10 species), long-lived larval endoparasites and short-lived gastrointestinal endoparasites (eight species each). Prevalence and abundance values of the former two guilds allowed analysing them comparatively to assess their value as biological indicators of both host population structure and zoogeography. Results of analyses on long-lived parasites evidenced the existence of three stocks, one in the regions of Rio de Janeiro and Sao Paulo, other in southern Brazil (Rio Grande do Sul) and a third in northern Argentina (Mar del Plata), responding to the differential environmental conditions characteristic of three zoogeographical ecoregions. Ectoparasite assemblages exhibited significant differences between all pairs of samples, including those considered as a single stock according to data on persistent parasites. Assemblages of long-lived larval parasites are considered as better indicators for stock assessment purposes than ectoparasites, whose population parameters were variable temporally and heterogeneous at small spatial scales. The distributional variability of persistent parasites of P. pagrus along large scales provides valuable information to help defining robust biogeographical patterns, applicable to stock identification and fishery management of this species.

Conversion of wine lees and waste activated sludge into caproate and heptanoate: Thermodynamic and microbiological insights.

In this study, wine lees and waste activated sludge (WAS) were co-fermented for the first time in a 4:1 ratio (COD basis) at 20, 40, 70 and 100 gCOD/L, in batch at 37 °C and pH 7.0. The substrates were successfully converted to caproate (C6) and heptanoate (C7) with a high selectivity (40.2 % at 40 gCOD/L). The rapidly-growing chain-elongating microbiome was enriched inClostridiaceaeandOscillospiraceae, representing together 3.4-8.8 % of the community. Substrate concentrations higher than 40 gCOD/L negatively affected C6 and C7 selectivities and yields, probably due to microbial inhibition by high ethanol concentrations (15.82-22.93 g/L). At 70 and 100 gCOD/L, chain elongation shifted from ethanol-based to lactate-based, with a microbiome enriched in the lactic acid bacteriaRoseburia intestinalis(27.3 %) andEnterococcus hirae(13.8 %). The partial pressure of H2(pH2) was identified by thermodynamic analysis as a fundamental parameter for controlling ethanol oxidation and improving C6 and C7 selectivities.

Ontogenetic changes in heterogeneity of parasite communities of fish: disentangling the relative role of compositional versus abundance variability.

In order to determine how much of the variability in parasite assemblages is driven by differences in composition or in abundance we used multivariate dispersions (average distance from infracommunities to their size class centroid in the multivariate space) as a measurement of ß-diversity in infracommunities of Conger orbignianus, applying a set of dissimilarity measures with different degrees of emphasis on composition versus relative abundance information. To evaluate comparatively the rate of such changes, we also analysed the effect of host size by regressing differences in ß-diversity among size classes against differences in mean fish size. Multivariate dispersions varied along an ontogenetic gradient, its significance depending on the measurement used. Larger fish showed higher richness and abundance; however, smaller fish displayed lower variations in abundance but higher in composition. This could be caused by stochastic encounters at low densities due to the overdispersion of parasites in previous hosts. As fish grow, the composition of their parasite assemblages becomes homogenized by repeated exposure, with abundance thus arising as the main source of variability. Both variables act at different rates, with the exponential decay in the compositional variability as differences in fish size increase being about twice as steep as the decay in abundance variability, indicating that compositional homogeneity is reached faster than abundance heterogeneity as fish grow. Discerning between both variables is crucial in order to understand how community structure is formed by size-dependent variability of host populations.

Hydrodynamic cavitation pre-treatment of urban waste: Integration with acidogenic fermentation, PHAs synthesis and anaerobic digestion processes.

Urban waste can be valorized within a biorefinery approach, producing platform chemicals, biopolymers and energy. In this framework, hydrodynamic cavitation (HC) is a promising pre-treatment for improving biodegradability due to its high effectiveness and low cost. This paper deals with the effect of HC pre-treatment on the acidogenic co-fermentation process of thickened sewage sludge from a WWTP and seasonal vegetable waste from a wholesale market. Specifically, HC was assessed by testing two sets of parameters (i.e., treatment time of 30 and 50 min; vacuum pressure 1.4 and 2.0 bar; applied power 8 and 17 kW) to determine its effectiveness as a pre-treatment of the mixture. The highest increase in sCOD (+83%) and VFAs (from 1.93 to 17.29 gCODVFA L-1) was gained after 50 min of cavitation. Fermentations were conducted with not cavitated and cavitated mixtures at 37 °C on 4 L reactors in batch mode, then switched to semi-continuous with OLR of 8 kgTVS m-3 d-1 and HRT of 5-6.6 d. Good VFAs concentrations (12.94-18.27 gCODVFA L-1) and yields (0.44-0.53 gCODVFA gVS(0)-1) were obtained, which could be enhanced by pre-treatment optimization and pH control. The organic acid rich broth obtained was then assessed as a substrate for PHAs storage by C. necator. It yielded 0.37 g g-1 of polyhydroxybutyrate, such biopolymer resulted to have analogous physicochemical characteristics of commercial equivalent. The only generated side-stream would be the solid-rich fraction of the fermented effluent, which valorization was assessed through BMP tests, showing a higher SGP of 0.42 Nm3 kgTVS-1 for the cavitated.

Congenital ptosis and blefarophimosis: retrospective analysis of the effectiveness of correction with levator resection and frontalis suspension.

BACKGROUND: treatment of congenital ptoses and blepharophimoses relies on levator resections and frontalis suspensions. Several techniques of levator resection have been described in literature, some of them include tarsal resections and resections of the Müller muscle. Nevertheless a gold treatment have not been detected yet. Frontalis suspension is performed when levator muscle is not functional or when ptosis is severe. The suspension could be carried out with several materials: ePTFE, silicon rods, poly-propylene, nylon, braided poliester, but the preferable material is considered the autologous fascia lata. AIMS: this study was designate to determine retrospectively if the indications of surgery are correct, considering age, severity of pathology, relapses and complications. An analysis of demographic data and outcomes for each technique is performed. METHODS: in this study we analyze case series of 33 pediatric patients affected by congenital ptosis and blepharophimosis congenital syndrome, surgically treated from 2000 to 2008 in the ophtalmic pediatric surgery department at the Niguarda Hospital of Milan. A literature review was also performed. RESULTS: the mean age at presentation was 4.13. The diagnosis was precocious in most cases and often helped by some recognizable clinical signs: compensatory head posture (48.5%), anisometropia (36.4%), astigmatism (48.5%), strabismus (36.4%) and amblyopia (15.2%). Most of patients was treated with frontalis suspension (57.6%) and their age was significatively lower than patients treated with levator resection. No difference about complications and recurrence was reported between the two techniques. Complications and recurrence amount to 39.4%. CONCLUSION: these results are in line with other studies in literature. A precociuos treatment is able to reduce the incidence of amblyopia from 34% to 8%. The choice of the treatment (resection Vs suspension) has to consider the age of the patient, the severity of ptosis and avaibility of fascia lata. Nevertheless no significative difference in outcomes have been demonstrated between the two techniques.

Consequences of microhabitat selection for reproductive success in the parasitic copepod Neobrachiella spinicephala (Lernaeopodidae).

SUMMARY: Narrow site specificity in parasites is assumed to be associated with fitness benefits, such as higher reproductive success, although this is never quantified. We linked the body mass and combined mass of egg sacs of female copepods, Neobrachiella spinicephala, parasitic on the sandperch, Pinguipes brasilianus, to attachment sites on the host. Adult females attach permanently either on the lips, the margins of the operculum, or the base of pectoral or pelvic fins. In addition to influences of sampling site, season and host body length, our analyses revealed important fitness effects. First, attachment site significantly influenced copepod body mass; independent of other factors, copepods at the base of fins were 32% larger than those on the lips or operculum. Second, the mass of egg sacs was almost always greater if the copepod was attached at the base of fins rather than to the lip or operculum. Thus, a female weighing 6 mg would, on average, produce 40% larger egg sacs if attached to the base of fins. However, copepods were much more likely to attach at the base of fins on small fish, and on either the lip or the operculum on large fish. We propose that constraints varying with fish size account for the shift from optimal to suboptimal attachment sites as a function of increasing host size. By measuring differences in fitness components between attachment sites, our approach allows hypothesis testing regarding microhabitat selection.

The metazoan parasite communities of the Argentinean sandperch Pseudopercis semifasciata (Pisces: Perciformes) and their use to elucidate the stock structure of the host.

The use of parasites as biological tags allowed the identification of 3 stocks of Argentinean sandperch, Pseudopercis semifasciata (Cuvier), in the Argentine Sea. A total of 100 specimens caught in 3 zones: Villa Gesell (37 degrees 15'S, 57 degrees 23'W; n=20), Miramar (38 degrees 03'S, 57 degrees 30'W-38 degrees 44'S, 58 degrees 44'W; n=30) and Península Valdes (42 degrees 00'-42 degrees 45'S; n=50), were examined and 28 parasite species were found, 15 of them being new host records. Both univariate and multivariate analyses identified discrete stocks in each zone. The observed differences were not related to the host size or sex. Each locality was characterized by its own indicator species. Villa Gesell was typified by unidentified cestode plerocercoids, Corynosoma cetaceum and Hysterothylacium sp., Miramar by Heterosentis sp. and Pseudoterranova sp. and Península Valdes by A. simplex s.l. Fishes from both northern localities shared gnathiid pranizae, Corynosoma australe and Grillotia sp. as indicators, whereas Miramar and Península Valdes shared only Trifur tortuosus. The most distant localities showed no indicator species in common. Discriminant analyses of parasite assemblages agreed with populational comparisons in identifying the same set of biological tags, whereas some differences in the identity of indicator species were obtained by similarity analysis. However, the 3 approaches were congruent in identifying Grillotia sp., C. australe and C. cetaceum as indicators of northern localities, and A. simplex s.l. as related to Patagonian waters. Differences among zones could be enhanced by the sedentary habits, limited dispersal and high site fidelity of P. semifasciata, and their spawning in rocky outcrops, which are isolated environments.

Seasonal stability and spatial variability of parasites in Brazilian sandperch Pinguipes brasilianus from the Northern Argentine Sea: evidence for stock discrimination.

The use of parasites as biological tags allowed the identification of two stocks of Brazilian sandperch Pinguipes brasilianus, in the Bonaerense region of the Argentine Sea. A total of 156 adult specimens of P. brasilianus were examined for parasites. Temporal variability in parasite burdens was assessed from fish caught seasonally in coastal waters of two zones, south Bonaerense (during autumn and winter) and north Bonaerense (during summer). Additional data from a previous study, comprising P. brasilianus caught during spring in these two zones, as well as in two populations from north Patagonian gulfs were used for comparative analyses of spatial variability. A total of 14 193 metazoan parasites belonging to 19 species were found. Comparisons of seasonal variability in pooled samples and within each locality showed that locality effects exceeded seasonal ones, suggesting the possible existence of two discrete stocks in the Bonaerense region. These findings were strongly supported by discriminant analyses and comparisons of prevalence and abundance between zones, after pooling seasonal samples within each zone. Further evidence of the discreteness of both stocks was assessed by inclusion of samples from Patagonian gulfs in the discriminant analysis, confirming that their differences were at a inter-population level. The parasite species that contributed most to the separation of the samples were generally those identified as biological markers in previous studies. Differing oceanographic conditions are discussed as potential causes of inter-population variation of parasite burdens.

Parasite infracommunities of a specialized marine fish species in a compound community dominated by generalist parasites.

The structure and composition of parasite communities of Mullus argentinae were analysed under two alternative hypotheses in a sample of 75 specimens caught off Mar del Plata, Argentina (38 degrees 27'S, 57 degrees 90'W). The first, based on the dominance of trophically transmitted larval parasites of low host-specificity among fish species in the region, predicts that infracommunities will be random subsets of regionally available species. The second, based on previous studies on other mullids, predicts that infracommunities will be dominated by adult digeneans. The parasite fauna of goatfishes was mainly composed of endoparasites, with metacercariae of Prosorhynchus australis accounting for most individual parasites and greatly affecting infracommunity descriptors. Its importance was reinforced by the low number of trophically transmitted larval parasites. Both hypotheses were refuted; parasite communities were not dominated either by trophically transmitted larval parasites of low host-specificity or by adult digeneans. Prosorhynchus australis was the only species displaying any degree of phylogenetic specificity. Therefore, the influence of phylogenetic factors seems to exceed that of ecological ones in determining the observed structure of infracommunities. However, it is precisely host ecology that allows P. australis to become the determinant of infracommunity structure by constraining the acquisition of other parasites. Studies aiming to determine the relative importance of evolutionary and ecological processes as structuring forces of parasite communities should take into account not only the identity and specificity of their component parasites, but also their availability in the compound community.

Stem cell transplantation for primary immunodeficiencies.

BMT is curative in almost 75% of children affected by severe primary immunodeficiencies (PIDs). Recently, the chance of cure has increased thanks to the availability of matched unrelated donors (MUDs). Nevertheless, besides the conventional indications to BMT (profound or absent T-cell function, profound or absent natural killer function, known syndromes with T-cell deficiencies), indications to BMT for PIDs affecting the quality of life or having an expectation of life that does not exceed the third-fourth decade remain unclear. Infact, if it is evident that the survival rate in an infant grafted for a PID with a MUD is expected to be more than 80%, alternative treatments such as gene therapy are now available.

Adult stem cells: perspectives for therapeutic applications.

The use of adult stem cells in tissue regeneration appears to be a powerful research tool, due to the intrinsic characteristics of these cells, i.e., self-renewal and unlimited capacity for proliferation. In particular, mesenchymal stem cells (MSCs) obtained from bone marrow or peripheral blood can be easily isolated, cultivated, propagated and can be differentiated into several specialized cell types thanks to their plasticity. Among these cells, MSCs can evolve into cardiac cell lineages. Since heart damage leads to the irreversible loss of cardiac function, cell transplantation could be a potential therapy for heart injury. Our laboratory has focused on the purification and expansion of rat and sheep MSCs, their differentiation into cardiomyocytes and their characterisation. Numerous results indicate that MSCs could be promising for therapy, however we need to better understand the biology of stem cells to improve methods for delivery and/or pharmacological activation. These techniques can indeed track engrafted cells and systems to guarantee their safe use.

Stem cell transplantation for the Wiskott-Aldrich syndrome: a single-center experience confirms efficacy of matched unrelated donor transplantation.

The treatment of Wiskott-Aldrich syndrome (WAS), a once uniformly fatal disorder, has evolved considerably as the use of hematopoietic stem cell transplant has become more widespread. For the majority of patients who lack an human leukocyte antigen-identical sibling, closely matched unrelated donor bone marrow transplant (MUD BMT) at an early age is an excellent option that nevertheless is not uniformly chosen. We retrospectively analyzed our experience with transplantation in 23 patients with WAS from 1990 to 2005 at the University of Brescia, Italy, of whom 16 received MUD BMT. Myeloablative chemotherapy was well tolerated with median neutrophil engraftment at day 18, and no cases of grade III or IV graft-vs-host disease. Overall survival was very good with 78.2% (18/23) of the whole cohort and 81.2% (13/16) of MUD BMT recipients surviving. Among 18 survivors, full donor engraftment was detected in 12 patients, and stable mixed chimerism in all blood lineages in four patients. Deaths were limited to patients who had received mismatched related BMT or who had severe clinical symptomatology at the time of transplantation, further emphasizing the safety and efficacy of MUD BMT when performed early in the clinical course of WAS.

Striped weakfish (Cynoscion guatucupa): a biomonitor of organochlorine pesticides in estuarine and near-coastal zones.

The general goal of this study was to investigate the role of Cynoscion guatucupa as a biomonitor of organochlorine pesticides (OCP) contamination in Bahía Blanca estuary. Thus, we evaluated whether or not OCP fish distribution pattern reflects the OCP land sources, and if size-related bioaccumulation and biomagnification of these contaminants does occur by comparing different tissues of juvenile and adults of C. guatucupa (Cuvier, 1830). Size-related bioaccumulation in C. guatucupa was observed and it was more important for the more lipophilic and biomagnifying OCP, being determined over time by diet influence. Endosulfan sulfate, chlordanes, HCH isomers and DDT compounds predominated in tissues and ingested food of C. guatucupa, being alpha-chlordane, heptachlor and p,p'-DDE highly bioaccumulated and biomagnificated. Our findings also showed that male adults of C. guatucupa are biomonitors of OCP pollution so we propose this species for further investigations in other coastal zones of South America.

Hematopoietic stem cell transplantation in Omenn syndrome: a single-center experience.

We retrospectively analyzed the outcome of hematopoietic stem cell transplantations (HSCT) performed at our Center between 1991 and 2002 in 11 unselected patients with Omenn syndrome, a variant of severe combined immunodeficiency. The patients' mean age at the time of the first HSCT was 8.4 months. Two patients received two, and one patient three, HSCT procedures. The resulting 15 HSCT derived in seven cases from HLA-haploidentical parents, in four patients from matched unrelated donors, in three cases from an HLA phenotypically identical related donor, and in one case from an HLA genotypically identical family donor. Nine out of 11 patients are alive and immunoreconstituted 30-146 months after transplantation. At the time of the most recent evaluation, all of the nine survivors had normal T-cell function, and eight of them had developed normal antibody production. This study demonstrates an overall mortality of 18.2%, which is substantially lower than previously reported. Early recognition of OS, rapid initiation of adequate supportive treatment and HSCT lead to improved outcome for this otherwise fatal disease, regardless of the origin and matching of hematopoietic stem cells.

Autologous bone marrow transplantation for acute myeloid leukaemia in children using total body irradiation and melphalan as conditioning regimen.

We conducted a phase II study on 19 children with AML in first (10 patients) or second (nine patients) complete remission (CR) treated with ABMT, evaluating the combination of total body irradiation (TBI, 12 Gy in six divided fractions) and high-dose melphalan (140 mg/m2 in single dose) in an attempt to improve antitumour efficacy of conditioning regimen. All patients received cryopreserved and in vitro purged (mafosfamide at a dose of 100 micrograms/ml) bone marrow. The median time from first CR to ABMT was 5 months compared with a median time of 3 months for patients in second remission. One of the 19 patients, transplanted in second CR, died of transplant-related complication 10 days after transplant and another second CR patient relapsed on day +28, before engraftment. Three further patients in second CR relapsed at 6, 6 and 18 months after marrow transplant, respectively, and this determined a relapse rate of 43% in children given ABMT in second CR and 0% for patients transplanted in first remission (P < 0.05). Seventy-two per cent of all patients are projected to be alive and disease-free at 6 years, whereas the event-free survival of patients in first and in second CR is 100 and 44%, respectively (P < 0.05). Although the number of patients does not allow us to draw any firm conclusion, our results are encouraging and suggest that the association of TBI and high-dose melphalan appears to be safe and valuable.

Baroreflex control of sympathetic nerve activity in essential and secondary hypertension.

Studies performed in experimental animals and in humans have documented that high blood pressure markedly impairs baroreceptor control of heart rate. Whether a similar impairment also characterizes baroreceptor control of sympathetic activity modulating peripheral vasomotor tone is still unknown. In 28 untreated essential hypertensive subjects [14 of moderate and 14 of more severe degree, age 51.6+/-2.4 and 52.6+/-2.1 years (mean+/-SEM)] and in 13 untreated secondary hypertensives (renovascular or pheochromocytoma, age 50.1+/-4.6 years), we measured beat-to-beat arterial blood pressure (finger photoplethysmographic device), heart rate (electrocardiogram), and efferent postganglionic muscle sympathetic nerve activity (microneurography) at rest and during baroreceptor stimulation and deactivation induced by stepwise intravenous infusions of phenylephrine and nitroprusside, respectively. Data were compared with those obtained in 15 age-matched normotensive control subjects. Muscle sympathetic nerve activity (bursts per 100 heart beats) showed a progressive and significant (P<.01) increase from normotension (40.3+/-3.3) to moderate (55.6+/-4.1) and more severe essential hypertension (68.2+/-4.1), paralleling the progressive increase in blood pressure values. In contrast, muscle sympathetic nerve activity was not increased in secondary hypertensives (40.5+/-6.7) despite blood pressure values similar to or even greater than those of severe essential hypertensives. In both essential and secondary hypertensives, baroreceptor-heart rate control was displaced toward elevated blood pressure values and markedly impaired compared with normotensive subjects (average reduction, 38.5%). In contrast, the sympathoinhibitory and sympathoexcitatory responses to baroreceptor stimulation and deactivation were displaced toward elevated blood pressure values but similar in all groups. Thus, sympathetic activation characterizes essential but not secondary hypertension. Regardless of its nature, however, hypertension is not accompanied by an impairment of baroreceptor modulation of sympathetic activity.

Baroreflex impairment by low sodium diet in mild or moderate essential hypertension.

Low sodium intake is the most widely used nonpharmacological approach to the treatment of hypertension. Although nonpharmacological treatment is by definition regarded as safe, the suggestion has been made that low sodium intake is not totally devoid of inconveniences, and animal data have shown it to be accompanied by an impairment of reflex blood pressure control and homeostasis. However, no data exist on this issue in humans. In mild essential hypertensive patients (age, 34.1+/-3.3 years [mean+/-SEM]), we measured beat-to-beat arterial blood pressure (finger photoplethysmographic device), heart rate (electrocardiogram), and efferent postganglionic muscle sympathetic nerve activity (microneurography) at rest and during baroreceptor stimulation and deactivation, induced by stepwise intravenous infusions of phenylephrine and nitroprusside, respectively. Measurements were performed at the end of three dietary periods, ie, after 8 days of regular sodium intake (210 mmol NaCl/d), low sodium intake (20 mmol NaCl/d) with unchanged potassium intake, and again regular sodium intake. Compared with the initial regular sodium diet, low sodium intake reduced urinary sodium excretion, whereas urinary potassium excretion was unchanged. Systolic blood pressure was significantly (P<.05), although slightly, reduced, whereas diastolic blood pressure was unaffected. Muscle sympathetic nerve activity was increased by 23.1+/-5.2% (P<.05). The increase was accompanied by a clear-cut impairment of the baroreceptor ability to modulate muscle sympathetic nerve activity, ie, by a 43.9+/-5.7% (P<.01) reduction in the sensitivity of the baroreceptor-muscle sympathetic nerve activity reflex compared with the control condition. Baroreceptor modulation of heart rate was also impaired, although to a smaller and less consistent extent. When regular sodium intake was restored, all the above-mentioned parameters and baroreflex responses returned to the values observed at the initial regular sodium diet. These data raise evidence that in humans sodium restriction may impair the arterial baroreflex. This may be responsible for the sympathetic activation occurring in this condition and for the impairment of blood pressure homeostasis.

Sympathetic activation in obese normotensive subjects.

Human obesity is characterized by profound alterations in the hemodynamic and metabolic states. Whether these alterations involve sympathetic drive is controversial. In 10 young obese subjects (body mass index, 40.5 +/- 1.2 kg/m2, mean +/- SEM) with normal blood pressure and 8 age-matched lean normotensive control subjects, we measured beat-to-beat arterial blood pressure (Finapres technique), heart rate (electrocardiogram), postganglionic muscle sympathetic nerve activity (microneurography at the peroneal nerve), and venous plasma norepinephrine (high-performance liquid chromatography). The measurements were performed in baseline conditions and, with the exception of plasma norepinephrine, during baroreceptor stimulation and deactivation caused by increases and reductions of blood pressure via intravenous infusions of phenylephrine and nitroprusside. Baseline blood pressure and heart rate were similar in obese and control subjects. Plasma norepinephrine was also similar in the two groups. Muscle sympathetic nerve activity, however, was 38.6 +/- 5.1 bursts per minute in obese subjects and less than half that level in control subjects (18.7 +/- 1.3 bursts per minute), the difference being highly statistically significant (P < .02). Muscle sympathetic nerve activity and heart rate were reduced during phenylephrine infusion and increased during nitroprusside infusion, but the changes were about half as great in obese subjects as in control subjects. Thus, even in the absence of any blood pressure alteration, human obesity is characterized by a marked sympathetic activation, possibly because of an impairment of reflex sympathetic restraint. This may be involved in the high rate of hypertension and cardiovascular complications seen in obesity.

Developing pigeon retina: light-evoked responses and ultrastructure of outer segments and synapses.

Morphological development of photoreceptor outer segments and synapses in the foveal region of the pigeon retina was studied by electron microscopy. In addition, the maturation of outer retina function was investigated by recording electroretinographic (ERG) responses to either flash or pattern stimuli. The first ERGs to unpatterned or patterned stimulation can be recorded at 4-6 days posthatching. These results are consistent with anatomical analysis of pigeon photoreceptor and synapse development. Indeed, photosensitive lamellae in the outer segments can be observed simultaneously with the appearance of the first retinal responses to light. A few synapses can already be seen in the outer plexiform layer at the time photoreceptor disks first appear. In contrast, numerous synapses are already present in the inner plexiform layer when photoreceptor lamellae have yet to appear. A comparable maturation pattern has been reported to occur in chicks toward the end of the incubation time.