Dem-Aging: autophagy-related pathologies and the "two faces of dementia".

Neuronal ceroid lipofuscinosis (NCL) is an umbrella term referring to the most frequent childhood-onset neurodegenerative diseases, which are also the main cause of childhood dementia. Although the molecular mechanisms underlying the NCLs remain elusive, evidence is increasingly pointing to shared disease pathways and common clinical features across the disease forms. The characterization of pathological mechanisms, disease modifiers, and biomarkers might facilitate the development of treatment strategies.The DEM-AGING project aims to define molecular signatures in NCL and expedite biomarker discovery with a view to identifying novel targets for monitoring disease status and progression and accelerating clinical trial readiness in this field. In this study, we fused multiomic assessments in established NCL models with similar data on the more common late-onset neurodegenerative conditions in order to test the hypothesis of shared molecular fingerprints critical to the underlying pathological mechanisms. Our aim, ultimately, is to combine data analysis, cell models, and omic strategies in an effort to trace new routes to therapies that might readily be applied in the most common forms of dementia.

The Minor's test in Frey syndrome treated with botulinum toxin: Methodology and efficacy.

In this paper, we aimed at methodologically presenting a video-case of Frey Syndrome occurred after parotidectomy, assessed by means of Minor's Test and treated with intradermic botulinum toxin A (BoNT-A) injection. Although largely described in the literature, a detailed explanation of both the procedures has not been previously elucidated. In a more original approach, we also highlighted the role of the Minor's test in identifying the most affected skin areas and new insight on the patient-tailored approach provided by multiple injections of botulinum toxin. Six months after the procedure, the patient's symptoms were resolved, and no evident signs of Frey syndrome were detectable through the Minor's test.

The prevalence of dysphonia and dysphagia in patients affected by immunomediated diseases and the role of psychometric tests.

This cross-sectional investigation examined the prevalence and severity of dysphonia, globus pharyngeus, and dysphagia in patients affected by immunomediated (IM) diseases. Seventy subjects were administered the Voice Handicap Index (VHI) (scale 0-4), Glasgow-Edinburgh Throat Scale (GETS) (scale from 0 to 7) for globus pharyngeus assessment, and modified Swallowing Outcomes After Revised Laryngectomy (SOAL) (scale 0, 1, 2) to test swallowing symptoms. VHI: the mean percentage of answers with a score greater than 1 (corresponding to a frequency of situation's occurrence "sometimes," "almost always," or "always") was 25.7, 26.7, and 44.1% for functional, emotional, and physical groups of sub-items respectively. GETS: the mean percentage of answers with a score ≥ 3 was 60.85%, significantly higher if compared with that of answers with a score < 3 (40.14%). The mean percentages of answers with a score 0-2, 3-4, and 5-7 were 40.1, 16.7, and 43.7% respectively. SOAL: a mean of 57.9% of answers gained a symptomatic score (1 ["a little"] or 2 ["a lot"]) and 41.9%, the score 0. The difference was statistically significant (p < 0.05). The first two most recurrent items with a score 2 ("a lot") were "Do you have a problem swallowing dry food?" (46%) and "Do you have a problem swallowing solid food?" (36%). The study represents the first to describe the globus pharyngeus symptoms in IM population. Moreover, it allows to confirm the recurrence of dysphonia and dysphagia in this type of patients. Particularly, it has been demonstrated that the alteration of swallowing function is related to solid and dry food. The self-assessment questionnaires proved as a useful tool to early detection of dysfunctions in order to avoid further deterioration of quality of life and to prevent serious life-threatening complications.

OnabotulinumtoxinA for adductor spasmodic dysphonia (ADSD): Functional results and the role of dosage.

OBJECTIVE: To report the results of functional outcome, dose trend and relationship between onabotulinumtoxinA (onabotA) dosage and the severity of disease or time between therapy sessions in patients affected by adductor spasmodic dysphonia (ADSD). PATIENTS AND METHODS: Thirty-two patients underwent 193 EMG-guided intracordal injections of a starting dose of 2 MU of onabotA. At enrollment, each subject was administered the VHI. The response was evaluated using a subjective rating scale (0-100% of normal phonation). RESULTS: The quality of voice improved significantly after 1 month and stabilized by 3 months. The percentage of normal voice improved 33.34 ±â€¯11.5% (min 26 - max 68). The functional gain was significantly worse in patients presenting with ADSD associated with dystonias in other body regions (31% vs 45% - p < 0.05). The mean dose employed was 3.64 MU (min 1 - max 6) with a trend of increasing dosages up to the 5th treatment after which the doses stabilized over time. The pre-treatment VHI showed a weakly positive correlation with the cumulative dose at the 5th and 10th injections. Benefit duration and the mean between treatment interval were 103 and 136 days respectively. The correlation between dose and inter-injection time is weakly negative (r = -0.22, p < 0.05), however, this is influenced predominantly by the first-to-second injection. After this initial treatment effect, the correlation becomes weakly positive (r = 0.12). CONCLUSIONS: Our data confirm the efficacy of onabotA to improve the quality of voice in cases of ADSD. The trial period for optimal dosage lasted up to a mean of five injections. The dosage of onabotA impacted the length of response and was influenced by the severity of ADSD. Finally the efficacy of onabotA did not change significantly after repeated administrations.

The role of masseter muscle EMG during DISE to predict the effectiveness of MAD: preliminary results.

The use of a mandibular advancement device (MAD) increases the activity of the temporo-mandibular (TM) complex and masseter (MM) muscles with the risk of reducing treatment compliance. Predictors of treatment outcome are of importance in selecting patients who might benefit from MAD without side effects. The role of mandibular advancement (MA) during drug-induced sleep endoscopy (DISE) is controversial. In three cases (BMI < 30) affected by non-severe OSAS (AHI < 30 e/h), we recorded the surface EMG signal of MM activity during DISE. At follow-up all cases improved the AHI, two cases that showed transient increase of MM activity did not suffer from changes of overjet and did not complain of discomfort with the use of MAD. The case that showed a continuing increase of MM activity reported TM discomfort without changes of dental occlusion. EMG of MM during DISE may contribute to ameliorate the selection of cases amenable to treatment with MAD.

Drug-induced sleep endoscopy as a selection tool for mandibular advancement therapy by oral device in patients with mild to moderate obstructive sleep apnoea.

Nowadays oral appliance therapy is recognised as an effective therapy for many patients with primary snoring and mild to moderate obstructive sleep apnoea (OSA), as well as those with more severe OSA who cannot tolerate positive airway pressure (PAP) therapies. For this reason, it is important to focus on objective criteria to indicate which subjects may benefit from treatment with a mandibular advancement device (MAD). Various anthropometric and polysomnographic predictors have been described in the literature, whereas there are still controversies about the role of drug-induced sleep endoscopy (DISE) and advancement bimanual manoeuvre as predictor factors of treatment outcome by oral device. Herein, we report our experience in treatment of mild moderate OSA by oral appliance selected by DISE. We performed a single institution, longitudinal prospective evaluation of a consecutive group of mild moderate patients with obstructive sleep apnoea syndrome who underwent DISE. During sleep endoscopy, gentle manoeuvre of mandibular advancement less than 5 mm was performed. In 30 of 65 patients (46.2%) we obtained an unsuccessful improvement of airway patency whereas in 35 of 65 patients (53.8%) the improvement was successful and patients were considered suitable for oral device application. Because 7 of 35 patients were excluded due to conditions interfering with oral appliance therapy, we finally treated 28 patients. After 3 months of treatment, we observed a significant improvement in the Epworth medium index [(7.35 ± 2.8 versus 4.1 ± 2.2 (p < 0.05)], in mean AHI [(21.4 ± 6 events per hour versus 8.85 ± 6.9 (p < 0.05)] and in mean ODI [(18.6 ± 8 events per hour to 7 ± 5.8 (p < 0.05)]. We observed that the apnoea/hypopnoea index (AHI) improved by up to 50% from baseline in 71.4% of patients selected after DISE for MAD therapy. In the current study, mandibular advancement splint therapy was successfully prescribed on the basis not only of severity of disease, as determined by the subject's initial AHI, but also by DISE findings combined with results of gentle mandibular advancement manoeuvre allowing direct view of the effects of mandibular protrusion on breathing spaces in obstruction sites, and showing good optimisation of selection of patients for oral device treatment.

Incidence and prevalence of lupus in Buenos Aires, Argentina: a 11-year health management organisation-based study.

OBJECTIVES: Studies regarding the epidemiology of systemic lupus erythematosus (SLE) are lacking in Argentina. Our purpose was to estimate the incidence and prevalence of SLE in a university hospital-based health management organisation in Buenos Aires (HIMCP). METHODS: For incidence calculation, the population at risk included all adult members of the HIMCP, with continuous affiliation for at least 1 year from January 1998 to January 2009. Each person was followed until he/she voluntarily left the HIMCP, death or finalisation of the study. Multiple methods for case finding were used to ensure complete ascertainment: (a) patients with problem SLE, undifferentiated autoimmune disease or mixed connective tissue disease in the Computer-based Patient Record System, (b) patients with positive antinuclear antibody test, anti-Sm antibodies and/or anti-dsDNA antibodies in the laboratory database and (c) patients who consumed hydroxichloroquine, chloroquine, azathioprine, cyclophosphamide, mycophenolate, cyclosporine or rituximab, from the administrative HIMCP drugs database. Medical records of all patients found were reviewed, and only patients fulfilling ACR criteria for SLE were included. Global and gender incidence rate (IR) was calculated. Prevalence was estimated on 1 January 2009, and the denominator population was the number of active members >18 years at that date (n=127 959). RESULTS: In the study period, 68 patients developed SLE. The observed IR (per 100 000 person-years, (CI 95%)) was 6.3 (4.9 to 7.7) for total population; 8.9 (CI 6.6 to 11.2) for women and 2.6 (1.2 to 3.9) for men. On 1 January 2009, 75 prevalent cases were identified. Prevalence rates (cases per 100 000 habitants, (CI 95%)) were 58.6 (46.1 to 73.5) for total population; 83.2 (63.9 to 106.4) for women and 23 (CI 11.9 to 40.1) for men. CONCLUSIONS: SLE incidence and prevalence rates in Argentina are in agreement with those of other studies from different parts of the world.

The speech range profile (SRP): an easy and useful tool to assess vocal limits.

This study was carried out to compare the vocal limits obtained by speech range profile (SRP) with those of voice range profile (VRP) in untrained healthy and dysphonic females. Forty-six healthy voice volunteers (control group) and 148 dysphonic patients (dysphonic group) were evaluated using videolaryngostroboscopic assessment and phonetography for voice measurements. For VRP, subjects were asked to sustain the vowel /a/ as soft and as loud possible from the lowest to the highest frequencies using an automated procedure. The SRP was obtained by recording the speaking voice (SV) and the shouting voice (ShV) asking subjects to read a list of sentences aloud and to shout / ehi/ as loud as they could, respectively. All subjects in the control and dysphonic groups were able to perform SRP. fourty of 46 (85%) and 102 of 148 (68.91%) cases, respectively in control and dysphonic groups, were able to perform VRP. Most frequently, the VRP was not recorded because of the inability to perform or, especially in the dysphonic group, for inadequacy of the vocal signal. In the control group, there were no significant differences between the mean values of Fmin, Fmax, Imin and number of semitones (st) of the VRP and those of the SRP (p > 0.05). In the dysphonic group, the mean values of Fmin, Fmax and st SV+ShV for SRP were significantly higher than those of VRP. Our preliminary results suggest that the SRP may be a useful, alternative tool to assess vocal limits in both euphonic and dysphonic females.

First record of Dero (Aulophorus) bimagnasetus Harman (Oligochaeta) from Brazil and habitat characteristics.

Annelid worms represent a significant part of freshwater benthic communities worldwide and Oligochaeta is a particularly species-rich group. Dero (A) bimagnasetus (Naididae) previously found and described from a small marsh in Surinam in 1974, has now been found for the first time in Barra Lake, MG, Brazil. Due to the scarce biological data and absence of ecological information in the literature regarding this species we are presenting morphological information on the specimens obtained and the physical and chemical characteristics of the habitat they were found. This species occurred only in the littoral zone of Barra Lake, in muddy, low oxygen, low conductivity and low organic matter sediment. The four individuals collected ranged 3.17-4.15 mm total length; 0.25 - 0.26 mm body width and 0.16-0.21 mm3 total volume. Considering the present anthropic pressures on freshwater biota and fast biodiversity losses worldwide it is now recognized that attention must be paid to low abundance species and the urgency for preservation of their habitats.

The role of drug-induced sleep endoscopy in the diagnosis and management of obstructive sleep apnoea syndrome: our personal experience.

Nowadays, drug-induced sleep endoscopy (DISE) is performed widely and its validity and reliability has been demonstrated by several studies; in fact, it provides clinical information not available by routine clinical inspection alone. Its safety and utility are promising, but still needs to be improved to reach the level of excellence expected of gold standard tests used in clinical practice. Our study compares the results of clinical and diagnostic evaluation with those of sleep endoscopy, evaluating the correlation between clinical indexes of routine clinical diagnosis and sites of obstruction in terms of number of sites involved, entity of obstruction and pattern of closure. This study consists in a longitudinal prospective evaluation of 138 patients who successfully underwent sleep endoscopy at our institution. Patients were induced to sleep with a low dose of midazolam followed by titration with propofol. Sedation level was monitored using bispectral index monitoring. Our results suggest that the multilevel complete collapse was statistically significantly associated with higher apnoea hypopnea index values. By including partial sites of obstruction greater than 50%, our results also suggest that multilevel collapse remains statistically and significantly associated with higher apnoea hypopnoea index values. Analyzing BMI distribution based on number of sites with complete and partial obstruction there was no significant difference. Finally, analyzing Epworth Sleepiness Score distribution based on number of sites with complete obstruction, there was a statistically significant difference between patients with 3-4 sites of obstruction compared to those with two sites or uni-level obstruction. In conclusion, our data suggest that DISE is safe, easy to perform, valid and reliable, as previously reported. Furthermore, we found a good correlation between DISE findings and clinical characteristics such as AHI and EPS. Consequently, adequate assessment by DISE of all sites of obstruction is very important, not only in patients with low-moderate AHI and EPS, but also in patients with a high AHI or/and high EPS, in particular to plan multilevel surgery that in these latter situations is more demanding since success may be harder to achieve.

Longitudinal distribution of Chironomidae (Diptera) downstream from a dam in a neotropical river.

The damming of a river causes dangerous consequences on structure of the environment downstream of the dam, modifying the sediment composition, which impose major adjustments in longitudinal distribution of benthic community. The construction of Engenheiro Sérgio Motta Dam in the Upper Paraná River has caused impacts on the aquatic communities, which are not yet fully known. This work aimed to provide more information about the effects of this impoundment on the structure of Chironomidae larvae assemblage. The analysis of data of physical and chemical variables in relation to biological data of 8 longitudinal sections in the Upper Paraná River showed that composition of Chironomidae larvae of stations near Engenheiro Sérgio Motta Dam differed of the other stations (farther of the Dam). The predominance of coarse sediments at stations upstream and finer sediments further downstream affected the choice of habitat by different morphotypes of Chironomidae and it caused a change in the structure of this assemblage in the longitudinal stretch.

Primary stabbing headache: a new dural sinus stenosis-associated primary headache?

Primary stabbing headache (PSH) is a primary syndrome of unknown aetiology, characterised by brief, jabbing stabs predominantly felt in the orbital, temporal and parietal areas, whose frequency may vary from one to many per day, usually responding to indomethacin. PSH frequency in the general population is not well defined, but recent evidence suggests it could be more frequent than previously thought. In clinical series, PSH incidence was 33/100,000 per year, while in a population study 35.2 % prevalence was found. PSH was previously described as isolated or associated to other headache syndromes, most frequently with migraine. There is evidence that an idiopathic intracranial hypertension without papilledema, a condition usually associated to significant stenosis of dural sinuses (93 % sensitivity and specificity), is much more prevalent than believed and may run asymptomatically in up to 11 % of otherwise healthy individuals. In migrainous prone people, a sinus stenosis-associated intracranial hypertension without papilledema (ss-IHWOP) comorbidity may represent a powerful risk factor for progression of pain. Besides migraine, significant sinus stenosis has been found overrepresented also in chronic tension type headache as well as in exertional, cough, sexual activity-associated headaches (all indomethacin responsive primary headaches) and in altitude headache (an acetazolamide responsive condition). To explore the possible association between venous outflow disturbances and PSH, we retrospectively investigated the co-occurrence of sinus venous stenosis in patients referring to our headache centre since 2004 diagnosed with PSH who completed the diagnostic protocol. Out of 50 consecutive patients reporting PSH as the main or as accessory complaint, 8 (6 females, 2 males) performed MR venography (MRV). All MRV revealed significant unilateral or bilateral sinus stenosis. Mean age at PSH onset was 35.3 ± 18.9 years (range 11-67 years). Duration of attacks ranged 1-3 s. Median daily frequency of attacks was 4 (range 2-20); median number of days per month with PSH presentation was 14 (range 4-30). Six patients described attacks in temporal or parietal areas, one at the top of the head, and one in the occipital area. Only one patient had isolated PSH; all the others were diagnosed also with migraine without aura. Seven out of eight patients responded to indomethacin 75 mg/die, and one to topiramate 100 mg/die. Interestingly, both drugs share with acetazolamide a CSF pressure lowering effect. Our findings indicate that PSH is associated with central sinus stenosis and suggest that an undiagnosed ss-IHWOP might be involved in PSH pathogenesis.

Complete transmural gastric migration of PTFE mesh after surgery for a recurrent hiatal hernia.

Complications directly associated with the use of prosthetic materials in large hiatal hernia repair are rarely cited events in the literature. We herein report a case of a 47 year-old woman who came to our attention for a subacute onset of severe dysphagia and weight loss. She previously underwent laparotomic Nissen fundoplication with PTFE dual-mesh cruroplasty for a large recurrent hiatal hernia. With the clinical suspicious of "Tight Nissen", an endoscopy was performed and revealed a circular stenosis in the lower esophagus, a rotation of the stomach and, surprisingly, the presence of PTFE mesh free-moving in the gastric lumen With the use of rattooth forceps, the foreign body was removed and, after few days, the patient underwent a surgical debridement of hiatal scar tissue and a gastropexy procedure. In conclusion, dysphagia may manifest during the early postoperative period after mesh repair antireflux surgery, but such dysphagia usually resolves; if it doesn't or if it worsens, mesh migration must be excluded.

Alternative treatment for otitis media with effusion: eustachian tube rehabilitation.

In this study, we evaluated the effectiveness of eustachian tube rehabilitation (ETR) as treatment for otitis media with effusion (OME). Thirty-five children with persistent OME were enrolled. Patients were divided into three groups: group I (isolated OME); group II (OME and atypical swallowing); group II (OME, habitual mouth breathing and atypical swallowing). All children underwent ETR. Otomicroscopy and tympanograms were performed before treatment, and at one and three months following ETR. Considering the overall patient population after ETR (one and three months later), the prevalence of type A tympanogram increased significantly compared to before therapy (p < 0.005), while the prevalence of type B tympanogram decreased significantly (p < 0.005). We found significant differences between pre- and both post-therapy control in groups I and II. However, children in group II experienced significant improvement of middle ear conditions only three months after the end of therapy (p < 0.005). On the basis of the physiopathologic knowledge of OME and the underlying principles of ETR, we conclude that ETR can be considered a useful therapy in management of OME.

The canalicular system and the osteoblast domain in human secondary osteons.

The lacunar-canalicular system in human secondary osteons was examined by two complementary techniques: light microscopy analysis of undecalcified thick sections and the SEM cortex-fractured surface technique. Unlike the earlier definitions of 'osteoblastic domain' presented as the matrix volume produced by osteoblasts in the process of osteon infilling, this study measured the domain by the length of osteoblast dendritic processes. The domain extension was defined along radial vectors advancing from the reversal line towards the central canal. According to their lengths, domains were divided into three classes: peripheral, intermediate and internal. The mean length of peripheral domains was significantly shorter than those of the intermediate and internal domains. This suggests that the infilling process is modulated by an initial preparatory phase characterised by osteoblast adhesion to the wall of the cutting cone, and a limited matrix synthesis, followed by a regular matrix volume apposition organised in concentric layers. In addition to the radial canaliculae arranged along converging vectors in planes perpendicular to the central canal, we distinguished a further class of canaliculae, the equatorial canaliculae originating from the major perimeter of the lacuna and spreading out radially in the plane of the same lacuna (therefore, perpendicularly to the radial canaliculae). The whole lacunar-canalicular network was structured as a closed system around the vascular axis of the central canal with very few canaliculae crossing the reversal line and connecting the neighbouring osteons. These anatomical observations contribute to our knowledge of lacunar-canalicular system development.

Growth and shape modelling of the rabbit tibia: study of the dynamics of developing skeleton.

The proliferative impulse of the growth plate cartilage and related structures and its effect on the dimensions of long bones are well documented. The modulation of shape, however, is less known, and in general, it is referred to the coupled resorption/apposition process of bone modelling. A morphometric study was carried out on rabbit tibiae comparing size increments and shape changes in relation to age. Utilizing measurements made using dried bones, radiography and computerized tomography, it was possible to perform a three-dimensional analysis of shape modulation occurring during a period of growth extending from 3 months to 1 year of age. The dynamics of the shape changes related to growth were studied with a fluorescent tetracycline labelling. This enabled correlation of shape modulation with the 3-D distribution of apposition and resorption. The current thinking behind the influences and mechanical forces affecting bone architecture was discussed in the light of these findings. Several factors play a role in the structural organization of the human and upper vertebrates' skeleton, whose shape is genetically determined in the complex process usually referred as 'modelling'. This does not conflict with the existing evidence of remodelling being influenced by mechanical stimuli, but the unsolved question remains how physical forces (strains) act on the biological substrate of cartilage and bone cells.

Environmental factors and benthic Oligochaeta (Annelida, Clitellata) assemblages in a stretch of the Upper São Francisco River (Minas Gerais State, Brazil).

The Oligochaeta forms an important part of the macroinvertebrates inhabiting sediments of lotic ecosystems. It has an important role in the cycling of matter and energy transfer in these environments. The aim of this study is to analyse limnological variables, their influence on the structure and diversity of benthic oligochaete taxocenosis in a stretch of the Upper São Francisco River and its tributary the Piumhi River. Samples were taken in two climatic periods, the dry season in October 2006 and 2007 and the rainy season in March 2007 and 2008 at three points along the Piumhi River and six points along the São Francisco River. The sediment of the São Francisco consisted predominantly of sand and clay, whereas the sediment of the Piumhi was mainly sandy. Six species of oligochaete occurred in the Piumhi River while seven were found in the São Francisco. Of these, Pristina synclites Stephenson, 1925, Pristina americana Cernosvitov, 1937, Bothrioneurum sp. Stolc, 1888 and Limnodrilus hoffmeisteri Claparede, 1862 occurred in the sediment of both rivers. L. hoffmeisteri showed the highest numerical abundance in the Piumhi River and Brinkhurstia americana (Brinkhurst, 1964) and L. neotropicus Cernosvitov, 1939 were the most abundant species in the São Francisco River. The highest oligochaete density was recorded in the Piumhi during the dry seasons. Canonical correspondence analyses (CCA) of sediment characteristics explained most of the data variability and the association of the presence of oligochaete species in the Piumhi and São Francisco Rivers with the limnological variables (grain size composition and total nitrogen and phosphorus concentrations in the sediment).

Feeding patterns of the aquatic grasshopper Cornops aquaticum (Bruner) (Orthoptera: Acrididae) in the middle Paraná river, Argentina.

The aquatic grasshopper Cornops aquaticum (Bruner) is native to South America and inhabits lowlands from southern Mexico to Central Argentina and Uruguay. This grasshopper is host-specific to aquatic plants of the genera Eichhornia and Pontederia. The objectives of this study were to analyze the feeding patterns of the aquatic grasshopper C. aquaticum in relationship to development stages and sex and to determine the food consumption rate in their host plant, Eichhornia crassipes. Samples were collected from April 2006 to May 2007 in different floodplain lakes of the Middle Parana River. The average consumption was greater in the females (0.127 g food/day ± 0.051) than in the males (0.060 g food/day ± 0.025). The feces of 361 nymphs and adults of this locust were examined and the most common tissue fragments found were of the water hyacinth (E. crassipes). In the initial nymphal stages (I, II and III), an exclusive consumption of E. crassipes was registered, while in the IV and V stages the choice included also other macrophytes. In summary, C. aquaticum presents polyphagy in the field, feeding on six macrophytes of different classes and families.

Environmental factors and benthic Oligochaeta (Annelida, Clitellata) assemblages in a stretch of the Upper São Francisco River (Minas Gerais State, Brazil) / Fatores ambientais e associações de Oligochaeta (Annelida, Clitellata) em um trecho do Alto Rio São Francisco (Minas Gerais, Brasil)

The Oligochaeta forms an important part of the macroinvertebrates inhabiting sediments of lotic ecosystems. It has an important role in the cycling of matter and energy transfer in these environments. The aim of this study is to analyse limnological variables, their influence on the structure and diversity of benthic oligochaete taxocenosis in a stretch of the Upper São Francisco River and its tributary the Piumhi River. Samples were taken in two climatic periods, the dry season in October 2006 and 2007 and the rainy season in March 2007 and 2008 at three points along the Piumhi River and six points along the São Francisco River. The sediment of the São Francisco consisted predominantly of sand and clay, whereas the sediment of the Piumhi was mainly sandy. Six species of oligochaete occurred in the Piumhi River while seven were found in the São Francisco. Of these, Pristina synclites Stephenson, 1925, Pristina americana Cernosvitov, 1937, Bothrioneurum sp. Stolc, 1888 and Limnodrilus hoffmeisteri Claparede, 1862 occurred in the sediment of both rivers. L. hoffmeisteri showed the highest numerical abundance in the Piumhi River and Brinkhurstia americana (Brinkhurst, 1964) and L. neotropicus Cernosvitov, 1939 were the most abundant species in the São Francisco River. The highest oligochaete density was recorded in the Piumhi during the dry seasons. Canonical correspondence analyses (CCA) of sediment characteristics explained most of the data variability and the association of the presence of oligochaete species in the Piumhi and São Francisco Rivers with the limnological variables (grain size composition and total nitrogen and phosphorus concentrations in the sediment).

Os Oligochaeta constituem uma parte importante dos macroinvertebrados bentônicos que habitam os sedimentos dos ecossistemas lóticos e tem papel relevante na ciclagem da matéria e transferência de energia nestes ambientes. O objetivo deste trabalho foi analisar as variáveis limnológicas e suas incidências sobre a estrutura e a diversidade da taxocenose de Oligochaeta presentes na comunidade bentônica de um trecho do alto rio São Francisco e de seu tributário, rio Piumhi. As coletas foram realizadas em dois períodos climáticos, o seco em outubro de 2006 e 2007 e o chuvoso em março de 2007 e 2008, amostrando-se três pontos no rio Piumhi e seis pontos no rio São Francisco. Os sedimentos do rio São Francisco foram predominantemente arenosos e argilosos, e no rio Piumhi ocorreram principalmente substratos arenosos. No rio Piumhi, ocorreram seis espécies de oligoquetos, enquanto que no rio São Francisco registrou-se a presença de sete espécies. Destas, Pristina synclites Stephenson, 1925, Pristina americana Cernosvitov, 1937, Bothrioneurum sp. Stolc, 1888 e Limnodrilus hoffmeisteri Claparede, 1862 ocorreram no sedimento de ambos os rios. L. hoffmeisteri foi registrada com maior abundância numérica no rio Piumhi e Brinkhurstia americana (Brinkhurst, 1964) e L. neotropicus Cernosvitov, 1939 foram as espécies mais abundantes no rio São Francisco. Os maiores valores de densidade foram registrados no rio Piumhi durante os períodos secos. As análises de correspondência canônica (CCA) para as características do sedimento permitiram explicar a variabilidade dos dados, associando a composição de espécies Oligochaeta, presentes nos rios Piumhi e São Francisco, com as variáveis limnológicas (composição granulométrica e concentrações de nitrogênio e fósforo total no sedimento).