A biological tool to assess flow connectivity in reference temporary streams from the Mediterranean Basin.

Many streams in the Mediterranean Basin have temporary flow regimes. While timing for seasonal drought is predictable, they undergo strong inter-annual variability in flow intensity. This high hydrological variability and associated ecological responses challenge the ecological status assessment of temporary streams, particularly when setting reference conditions. This study examined the effects of flow connectivity in aquatic macroinvertebrates from seven reference temporary streams across the Mediterranean Basin where hydrological variability and flow conditions are well studied. We tested for the effect of flow cessation on two streamflow indices and on community composition, and, by performing random forest and classification tree analyses we identified important biological predictors for classifying the aquatic state either as flowing or disconnected pools. Flow cessation was critical for one of the streamflow indices studied and for community composition. Macroinvertebrate families found to be important for classifying the aquatic state were Hydrophilidae, Simuliidae, Hydropsychidae, Planorbiidae, Heptageniidae and Gerridae. For biological traits, trait categories associated to feeding habits, food, locomotion and substrate relation were the most important and provided more accurate predictions compared to taxonomy. A combination of selected metrics and associated thresholds based on the most important biological predictors (i.e. Bio-AS Tool) were proposed in order to assess the aquatic state in reference temporary streams, especially in the absence of hydrological data. Although further development is needed, the tool can be of particular interest for monitoring, restoration, and conservation purposes, representing an important step towards an adequate management of temporary rivers not only in the Mediterranean Basin but also in other regions vulnerable to the effects of climate change.

A theoretical four-compartment model to evaluate separate kidney technetium-99m-MAG3 kinetics in humans.

BACKGROUND: Pharmacokinetic modeling based on compartmentalization has provided a valuable tool to assess the clearance patterns of various glomerular and tubular agents. However, no models have been proposed thus far that combine vascular data and imaging data in order to gain a deeper knowledge on renal pathophysiology, and to obtain more diagnostic information of clinical relevance. To this aim, we propose a four-pool model for the evaluation of separate renal function. METHODS: In a group of ten normal volunteers and twenty patients with various renal diseases, we tested the four-pool model based on the identification of the two kidneys as two distinct pools. This approach made it possible to integrate the separate kidney contributions deriving from in vivo imaging data, and allows the researcher to quantitate many parameters specific to each kidney. RESULTS: The parameters TERR, TERL, MRTR, MRTL, vR, vL, k3R-1, K3L-1 permit the normal from abnormal states of renal function to be differentiated, as well as monolateral from bilateral renal disease to be separated within the abnormal function group. CONCLUSIONS: The proposed approach combines the advantages of plasma clearance methods with those derived by gamma-camera imaging, and makes it possible to quantitate the differential renal function. This feature may be clinically relevant in renal transplant donors, where full knowledge of renal pathophysiology could guide the procedure.

The cognitive assessment of limited-English-proficient children: current problems and practical recommendations.

Children from limited-English-proficient backgrounds are frequently assessed for the purposes of classification, educational placement decisions, and intervention planning. Problems inherent in the process of identifying their intellectual strengths and weaknesses are discussed, including questionable special education referrals, the use of English as the language of testing, the use of interpreters, the administration of normed tools, and the use of translated tests. Among the practical recommendations explored are prereferral activities, assessment of language dominance and proficiency, training of bilingual personnel, the integration of multiple assessment tools, adaptation of available measures, and alternative assessment models.

Limitations of continuous 24-h intragastric pH monitoring in the diagnosis of duodenogastric reflux.

OBJECTIVE: Long term gastric pH monitoring has been proposed to diagnose abnormal duodenogastric reflux. This study analyses the in situ reproducibility of continuous intragastric pH measurements to assess the influence of artifactual factors in producing spontaneous variations of pH values that might be frequently misinterpreted as episodes of duodenogastric reflux. METHODS: The investigation was carried out in 301 endoscopically proven duodenal ulcer patients (87 female, 214 male, mean age 46 yr). Each patient underwent 24-h gastric pH monitoring with two closely adjacent pH electrodes whose tips were about 2 mm apart. The two simultaneous pH tracings obtained from each patient were analyzed with regard to the number, characteristics, and discrepancies of unexpected alkalinization waves over the entire circadian cycle. RESULTS: The simultaneous pH tracings of the two-channel datalogger we used ran almost superimposed for more than 23 h in 224 out of 301 (74%) duodenal ulcer patients. Major discrepancies between the two pH tracings of each recording were obtained in the remaining cases (77/301 = 26%). The most frequent event was represented by unexpected alkalinization waves that occurred mainly during nighttime and were recorded by only one of the two simultaneously measuring electrodes. As few as 16/244 (7%) patients showed synchronous, unexpected alkalinization waves that one might eventually consider to be duodenogastric refluxes. CONCLUSIONS: It is rather common that only one of two closely adjacent pH electrodes placed within the stomach measures longlasting pH elevations, particularly during the nocturnal period. This discrepancy is due to a poor in situ reproducibility of simultaneous pH recordings and indicates that pH readings might be influenced by interference and artifacts. Thus, the frequent differences between two simultaneous pH readings and the indirect measurement of the backflow of duodenal contents with long term gastric pH-metry do not allow us to rely on this technique to diagnose duodenogastric reflux.

Clinical assessment of corneal hydration control in Fuchs' dystrophy.

The diagnosis and monitoring of Fuchs' disease is typically based on information obtained from patient symptoms and a slitlamp examination. Although this clinical information provides a basis for diagnosis, it does not give a quantitative method for charting the progression of the disease systematically or a reliable basis for predicting the cornea's capacity to remain transparent after stress (e.g., cataract extraction). However, it is possible to quantify overall corneal hydration control by inducing corneal swelling and then monitoring the deswelling rate expressed as percent recovery per hour (PRPH). We have tested subjects with Fuchs' dystrophy and found that the PRPH provides a reasonable estimate of corneal hydration control. Unfortunately, the PRPH procedure involves considerable time and technical assistance and therefore is not convenient for clinical practice. In this report, we document the results of an initial effort to explore the relations between PRPH and six clinical measures consisting of five biomicroscopic indices and a subjective synthesis of clinical information called the probability of decompensation (POD) based on these indices. PRPH was significantly related to striae (p less than 0.001), stromal haze (p = 0.025), microcysts (p less than 0.001), and the POD (p less than 0.001) and not significantly related to guttae (p = 0.252) or Descemet's folds (p = 0.185). An empirically weighted predictor of PRPH was constructed from a statistical analysis of five slitlamp assessments and age. This approach for synthesizing clinical information produced a result at least as good as that obtained from the POD summary. These results show an important link between a quantitative laboratory assessment of corneal function and a clinical evaluation of corneal status and suggest that with continued refinement, clinical assessment may provide more quantitative information on Fuch's dystrophy and other diseases that affect corneal status.

Corneal hydration control in Fuchs' dystrophy.

Corneal hydration control was tested in 22 patients with Fuchs' dystrophy, and eight subjects of similar age without the disease, by measuring the corneal thickness recovery from swelling induced by hypoxia or following overnight sleep. Measurement precision was enhanced by using a modified optical pachometer and conducting two test procedures which were analyzed by a coupled exponential model. We have identified three parameters of the recovery from corneal swelling which may be used to describe hydration control: percent recovery per hour (PRPH) (mean 25.4% for Fuchs' and 34.2% for normals), time for 95% of corneal thickness recovery (mean 10.2 hr for Fuchs' and 7.1 hr for normals), and the open-eye steady-state thickness (mean 562 microns for Fuchs' and 537 microns for normals.) A PRPH of 17.1%/hr was identified as the minimum below which the cornea could not regain its open-eye steady state during the entire day and approaches decompensation. Our test procedure quantifies the corneal hydration control mechanism and may provide a test of endothelial function which can be used to monitor the progression of Fuchs' disease and guide decisions related to corneal surgery.

Age differences in corneal hydration control.

Dynamic changes in corneal thickness were measured in eight young and eight older normal subjects (mean ages 24.4 +/- 4.3 years and 71.9 +/- 7.3 years, respectively) to provide data for quantitative assessment of corneal hydration control and thereby provide information for studying age differences in this important aspect of corneal function. For each subject, pachometry data were obtained by (A) monitoring corneal recovery following hypoxic stress, and by either (B1) measuring recovery after sleep or (B2) by measuring corneal thickness in the late afternoon. The combined data from A and B1 or A and B2 were analyzed through an exponential model to provide information on the: (1) percent recovery per hour (PRPH) following induced corneal hydration; (2) open-eye steady-state (OESS) corneal thickness; (3) residual corneal swelling just before the hypoxic stress test; (4) amount of corneal edema induced by hypoxic stress; and (5) time to reach 95% recovery back to the OESS thickness level (T95%). The results show that between the two age groups, there are substantial differences in some characteristics of corneal hydration while other aspects are similar. For example, the mean PRPH values (58.9 +/- 7.8% and 34.2 +/- 6.4%/hr) were significantly higher in the younger subjects (P = 0.0002) and the mean time for 95% recovery to OESS thickness (207 +/- 42 min and 452 +/- 117 min) was significantly lower in the younger vs. the older group (P = 0.0002).(ABSTRACT TRUNCATED AT 250 WORDS)

Specular microscopy in aniridia.

Aniridia and the iridocorneal endothelial (ICE) syndromes both are conditions which include abnormalities of the cornea, iris, and progressive iridocorneal adhesions which may result in glaucoma. In order to investigate the similarities between aniridia and the ICE syndromes, we performed specular microscopy of the corneal endothelium in nine patients with aniridia. Morphology and density of the corneal endothelium appeared normal for age. We found no evidence of the beaten metal appearance classically seen on specular microscopy in patients with ICE symptoms. This study did not support either an anatomic or pathogenic relationship between aniridia and the ICE syndromes.

Chronic Propionibacterium endophthalmitis after extracapsular cataract extraction and intraocular lens implantation.

We studied six cases of chronic, indolent intraocular inflammation that occurred after extracapsular cataract extraction and posterior chamber intraocular lens implantation. The inflammation was characterized by a delayed onset, and in three cases had the clinical appearance of a granulomatous iridocyclitis. Cultures of intraocular specimens obtained from six eyes yielded Propionibacterium; five yielded P. acnes. Pleomorphic gram-positive bacilli consistent with Propionibacterium were identified in cytologic or histopathologic studies in four of the six culture-positive cases. After surgical and medical therapy, the inflammation resolved. Postoperative Propionibacterium endophthalmitis may masquerade as a chronic iridocyclitis.