A tale of time and depth: intralacustrine radiation in endemic Gammarus species flock from the ancient Lake Ohrid

Tentatively dated, the Plio‐/Pleistocene origin of the ancient Lake Ohrid on the Balkan Peninsula makes it the oldest ancient lake in Europe. Given the surface area of the lake and the adjusted endemicity rate, it may be also defined as the most diverse of all the ancient lakes in the world. From all the animal groups endemic to this lake, gammarids are amongst the most scarcely known in terms of their diversity and phylogenetic relationships. Partial DNA sequences of two mitochondrial genes, cytochrome oxidase subunit I (cox1) and 16S ribosomal RNA (16S rRNA) of eight known endemic Gammarus species from the Lake Ohrid valley were analysed. Phylogenetic analyses showed that endemic Gammarus species comprise an ancient species flock, with Gammarus sketi from the feeder springs being their sister taxon outside the lake. Amongst the species inhabiting the lake, Gammarus solidus and Gammarus salemaai are morphologically and molecularly well defined. By contrast, Gammarus ochridensis, Gammarus parechiniformis, Gammarus lychnidensis, and Gammarus stankokaramani revealed high discrepancy between morphological and genetic data. None of these morphospecies form a monophyletic clade and a significant degree of apparent gene flow occurs between them. This could be caused by incomplete lineage sorting and/or hybridization events. Two novel mtDNA lineages were found within the lake, possibly constituting two new species (Gammarus sp. 1 and Gammarus sp. 2). Molecular clock analysis showed that the split between G. sketi and the Gammarus species flock from the lake occurred approximately 5–7 Mya, whereas within the flock there were at least two intralacustrine radiations: one estimated at 2–3 Mya and the second at less than 1 Mya. The first one could be associated with the origin of the lake and the second with the lake water‐level fluctuations during Pleistocene. © 2013 The Linnean Society of London     

Bone biopsy in the diagnosis of renal osteodystrophy

When renal disease develops, mineral and vitamin D homeostasis is disrupted, resulting in diverse manifestations in bone cells and structure as well as the rate of bone turnover. In ESRF when patients require chronic maintenance dialysis, nearly all of them have abnormal bone histology named renal osteodystrophy (ROD). On the other hand, survival rates of patients on dialysis have increased with improved dialytic therapy and the resultant increased duration of dialysis has led to a rise in renal osteodystrophy. Because this metabolic bone disease can produce fractures, bone pain, and deformities late in the course of the disease, prevention and early treatment are essential. Serum PTH levels are commonly used to assess bone turnover in dialyzed patients. However, it is found that serum PTH levels between 65 and 450 pg/ml seen in the majority of dialysis patients are not predictive of the underlying bone disease. To date, bone biopsy is the most powerful and informative diagnostic tool to provide important information on precisely the type of renal osteodystrophy affecting patients, the degree of severity of the lesions, and the presence and amount of aluminum and strontium deposition in bone. Bone biopsy is not only useful in clinical settings but also in research to assess the effects of therapies on bone. Although considered as an invasive procedure, bone biopsy has been proven as safe and free from major complications besides pain, haematoma or wound infections, but the operator's experience and skill is important in minimizing morbidity. Alternatives to bone biopsy continue to be pursued, but the non-invasive bone markers have not been proven to hold sufficient diagnostic performance related to the bone turnover, mineralization process and bone cell abnormality. At present however, the transiliac bone biopsy remains the golden standard in the diagnosis of renal osteodystrophy.     

Patterns of genetic differentiation and population history of endemic isopods (Asellidae) from ancient Lake Ohrid: combining allozyme and mtDNA data

Ancient lakes as places of extensive speciation processes have been characterized by a high degree of endemicity and biodiversity. The most outstanding European ancient lake is the oligotrophic and karstic Balkan Lake Ohrid. The lake is inhabited by a number of endemic species, but their evolutionary history is largely unresolved. in the present study, the genetic structure, gene genealogy and demographic history of the representatives of the Ohridian endemic Proasellus species were studied using both biparentally (allozyme loci) and maternally (partial mitochondrial cytochrome oxidase subunit I gene) inherited markers. Both data sets gave similar results and supported discrepancies among genetic differentiation, the current morphology-based taxonomy and bathymetric segregation. Horizontal distribution of endemic Proasellus species (Lake Ohrid vs adjacent feeder springs) within the lake presumably promote parapatric speciation whereas the main role of vertical barriers into diversification processes was not fully supported. The analyses of demographic history suggested the decline of endemic isopod populations. The radiation of endemic Proasellus populations within the lake could have started from the sublittoral/profundal zone towards the littoral or in the opposite direction — from the littoral to the profundal. Our analyses did not exclude both possibilities.     

Zooplankton dynamic of Lake Prespa (Macedonia)

The composition and temporal abundance patterns of zooplankton community in Lake Prespa pelagic zone were studied throughout an annual cycle (October 2008–September 2009). Eighteen species (10 Rotifera, 5 Cladocera, 2 Copepoda, 1 Mollusca) were evidenced. It includes Arctodiaptomus steindachneri, an endemic calanoid of the Western Balkans. The zooplankton density varied during the investigated period and certain seasonal successions in temporal transpositions of their maximal development were noticed. The total zooplankton density was much higher in spring and summer period. The representatives of subclass Copepoda were dominant during the whole year. The dominant species was A. steindachneri. At the second place (with exception of the winter period) were the Cladocera representatives. The dominant species was Daphnia cucullata. At the third and fourth place were rotifers and larval form of Dreissena polymorpha, respectively. The quantitative presence of the Copepoda representatives was significantly lower in terms of the previous investigations. The Cladocera quantity reached high values during this period, particularly in summer. Such altering in the quantitative ratio between Copepoda and Cladocera in favor of the Cladocera, especially high quantitative presence of D. cucullata, typical for eutrophic lakes, imply of significant changes in zooplankton community and changes of the water quality in Lake Prespa pelagial.     

NT-ProBNP Levels in Saliva and Its Clinical Relevance to Heart Failure

Background

Current blood based diagnostic assays to detect heart failure (HF) have large intra-individual and inter-individual variations which have made it difficult to determine whether the changes in the analyte levels reflect an actual change in disease activity. Human saliva mirrors the body’s health and well being and ∼20% of proteins that are present in blood are also found in saliva. Saliva has numerous advantages over blood as a diagnostic fluid which allows for a non-invasive, simple, and safe sample collection. The aim of our study was to develop an immunoassay to detect NT-proBNP in saliva and to determine if there is a correlation with blood levels.

Methods

Saliva samples were collected from healthy volunteers (n = 40) who had no underlying heart conditions and HF patients (n = 45) at rest. Samples were stored at −80°C until analysis. A customised homogeneous sandwich AlphaLISA^(R) immunoassay was used to quantify NT-proBNP levels in saliva.

Results

Our NT-proBNP immunoassay was validated against a commercial Roche assay on plasma samples collected from HF patients (n = 37) and the correlation was r² = 0.78 (p<0.01, y = 1.705× +1910.8). The median salivary NT-proBNP levels in the healthy and HF participants were <16 pg/mL and 76.8 pg/mL, respectively. The salivary NT-proBNP immunoassay showed a clinical sensitivity of 82.2% and specificity of 100%, positive predictive value of 100% and negative predictive value of 83.3%, with an overall diagnostic accuracy of 90.6%.

Conclusion

We have firstly demonstrated that NT-proBNP can be detected in saliva and that the levels were higher in heart failure patients compared with healthy control subjects. Further studies will be needed to demonstrate the clinical relevance of salivary NT-proBNP in unselected, previously undiagnosed populations.     

Interference testing

* Interference occurs when a substance or process falsely alters an assay result. * Interferences are classified as endogenous or exogenous. Endogenous interference originates from substances present in the patient's own specimen. Exogenous interferences are substances introduced into the patient's specimen. * To perform interference studies, proper planning is required. * Interference from haemolysis, icterus and lipaemia are most frequently studied. Haemolysis affects more analytes than does any other type of interference. * Protein interferences are most often associated with paraproteins and predominantly with IgM or IgG and rarely with IgA. * Drug interference may be due to the parent drug, metabolite(s) or additives in the drug preparation. * Collection tube components can affect determination of analytes. * Carryover interference typically occurs when analyte from a high concentration sample (or reagent) is incompletely removed by the analytical system's washing process, whether probe, mixer or cuvette washing. * Immunoassay interferences are most commonly due to antibodies (generally polyclonal). They may be autoantibodies (e.g. in thyroid disease) or heterophile antibodies that predominantly interfere in two-site immunometric (sandwich) assays, forming a bridge between capture and detection antibodies. * Determining if interference is significant requires deviation limits from the original result. * Once interferences are identified during method evaluation or in general use, there is a need to establish procedures for handling affected results as part of the quality system.     

Investigation and management of moderate to severe inpatient hyponatraemia in an Australian tertiary hospital

Background

Hyponatraemia is the most common electrolyte disturbance amongst hospitalised patients. Both American and European guidelines recommend fluid restriction as first line treatment for SIADH, however differ on second line recommendations. The objective of this study was to examine investigation and management of hyponatraemia in hospitalised patients in an Australian tertiary hospital.

Methods

A retrospective audit was conducted of electronic medical records and laboratory data of inpatients with serum sodium (Na) ≤125?mmol/L, admitted over a 3?month period to the Princess Alexandra Hospital, Brisbane, Australia. The main outcomes measured included: demographic characteristics, investigations, accuracy of diagnosis, management strategy, change in Na and patient outcomes.

Results

The working clinical diagnosis was considered accurate in only 37.5% of cases. Urine Na and osmolality were requested in 72 of 152 patients (47.4%) and in 43 of 70 euvolaemic patients (61.4%). Thyroid function tests (67.1%) and morning cortisol (45.7%) were underutilized in the euvolaemic group. In the SIADH cohort, fluid restriction resulted in a median (IQR) 7.5?mmol/L (4–10.5) increase in Na after 3?days; no treatment resulted in a median 0?mmol/L (??0.5–1.5) change. Oral urea was utilized in 5 SIADH patients where Na failed to increase with fluid restriction alone. This resulted in a median 10.5?mmol/L (3.5–13) increase in Na from baseline to day 3. There were no cases of osmotic demyelination. The median length of stay was 8?days (4–18.5). Mortality was 11.2% (17 patients). There was a weak but significant correlation between nadir serum Na and mortality (R?=?0.18, P?=?0.031).

Conclusion

Inpatient hyponatraemia is often inadequately investigated, causing errors in diagnosis. Treatment is heterogeneous and often incorrect. In cases with hyponatraemia refractory to fluid restriction, oral urea presents an effective alternative treatment.

     

Differences in rotifer communities in two freshwater bodies of different trophic degree (Lake Ohrid and Lake Dojran,Macedonia)

We investigated monogonont rotifers in two natural Macedonian lakes that greatly differ in age, size and trophic state: Lake Ohrid and Lake Dojran. A main characteristic of Lake Ohrid is the scarcity of nutrients and consequently a low level of primary production. Lake Dojran represents a typical eutrophic lake. Results clearly indicate that species numbers are negatively correlated with trophic degree. Qualitative analyses of rotifer compositions in Lakes Ohrid and Dojran showed the presence of 70 and 55 taxa, respectively. Rotifer assemblages differed in their community structure, population densities, and the occurrence pattern of dominant species. The density of rotifers increased with increasing nutrient concentration, varying from min. 0.67 ind. L⁻¹ in June, 2006 to max. 8.2 ind. L⁻¹ in July, 2004 in Lake Ohrid, whereas min. 28.8 ind. L⁻¹ (in December, 2005) and max. 442.5 ind. L⁻¹ (in September, 2005) were recorded in Lake Dojran. Gastropus stylifer and Keratella cochlearis were the most abundant species in the pelagic zone of Lake Ohrid, averaging monthly densities of 1.2 ind. L⁻¹ and 0.6 ind. L⁻¹, respectively, thereby contributing 29% and 15% to rotifer abundance. In contrast, Lake Dojran rotifers were dominated by Brachionus spp. Brachionus diversicornis and Brachionus calyciflorus f. amphiceros were most abundant, comprising 40% and 25% of the total rotifer density. These results corroborate our idea, that the trophic state is an important factor in determining the composition of rotifer communities.     

Anatomical evidence of close affinity between endemic species of Pisidium (Bivalvia, Sphaeriidae) from some ancient lakes, and the widely distributed taxa

Anatomical characters of three endemic taxa from the Balkan lakes Ohrid and Prespa and one species from Lake Baikal were studied and compared with those of the widely distributed species of Pisidium . A close affinity of Pisidium edlaueri Kuiper 1960 from Ohrid and Pisidium maasseni Kuiper 1987 from Prespa to the Holarctic Pisidium nitidum Jenyns 1832 was confirmed; Pisidium raddei Dybowski 1902 from Baikal is anatomically identical to the Boreo-alpine Pisidium conventus Clessin 1877. Similarity in anatomical characters between the Ohridan subspecies Pisidium subtruncatum recalvum Kuiper 1960 and the nominal subspecies was also shown. These findings are compared with the situation in other ancient lakes. The similarity in some shell characters between the nonrelated taxa inhabiting these lakes is interpreted as being the result of convergent evolution.