Population growth of microcrustaceans in water from habitats with differing salinities

Inland salt marshes are a rare habitat in North America. Little is known about the invertebrates in these habitats and their ability to cope with the brackish conditions of the marsh. We studied the population growth of ostracods found in an inland salt marsh (Maple River salt marsh) and of copepods found in the wetland habitat immediately adjacent to the freshwater Kalamazoo River. By studying these species in water from both habitats, we aimed to find out if they performed differently in the two habitats. We also tested Daphnia pulex in water from the two habitats due to the history of Daphnia spp. as model organisms. We found that copepods performed better in water taken from the Maple River salt marsh, and the ostracods and D. pulex performed equally well in either water. This was unexpected, since ostracods are found in the salt marsh and copepods in the freshwater area. As a second experiment, we tested the invertebrates in pairwise interactions. In water from the Kalamazoo River, ostracods outperformed the other two species, but there was no difference between D. pulex and copepods. No species outperformed the other in salt marsh water. Our results show no local adaptation to salinity, suggesting that ostracods and copepods may be limited in their respective distributions by dispersal limitation or habitat suitability.

Diversity and composition of macroinvertebrate communities in a rare inland salt marsh

Inland salt marshes are rare habitats in the Great Lakes region of North America, formed on salt deposits from the Silurian period. These patchy habitats are abiotically stressful for the freshwater invertebrates that live there, and provide an opportunity to study the relationship between stress and diversity. We used morphological and COI metabarcoding data to assess changes in diversity and composition across both space (a transect from the salt seep to an adjacent freshwater area) and time (three sampling seasons). Richness was significantly lower at the seep site with both datatypes, while metabarcoding data additionally showed reduced richness at the freshwater transect end, consistent with a pattern where intermediate levels of stress show higher diversity. We found complementary, rather than redundant, patterns of community composition using the two datatypes: not all taxa were equally sequenced with the metabarcoding protocol. We identified taxa that are abundant at the salt seep of the marsh, including biting midges (Culicoides) and ostracods (Heterocypris). We conclude that (as found in other studies) molecular and morphological work should be used in tandem to identify the biodiversity in this rare habitat. Additionally, salinity may be a driver of community membership in this system, though further ecological research is needed to rule out alternate hypotheses.

ECG interpretation skill acquisition: A review of learning, teaching and assessment

The recording of 12 lead electrocardiograms (ECG) is one of the most useful and commonly performed medical procedures. ECGs are used in diagnosis, risk-stratification management decision-making, and assessment in response to therapy. The correct interpretation of 12 lead ECG recordings is complex and clinically challenging with misinterpretation having the potential to result in poor outcomes or even patient fatality. Despite its widespread use, several studies have highlighted deficiencies in ECG interpretation skills among health professionals. The literature suggests that up to 33% of ECG interpretations have some error when compared to the expert reference and up to 11% resulted in inappropriate management. The pedagogy of ECG interpretation lacks universal establishment; time allocation, faculty training and teaching format vary considerably within the literature. This review of the literature reports how a lack of established ECG reporting methods may contribute to the variation in reported ECG interpretation competence across many healthcare professionals. The ubiquity of the ECG in clinical practice and an over reliance on computer assisted ECG interpretation are additionally explored as factors affecting acquisition and retention of this clinical skill.

Genetic abnormalities in a pre and post-chemotherapy hepatoblastoma

Comparative genomic hybridization (CGH) analysis was performed on both a pre- and post-chemotherapy hepatoblastoma from a 24-month-old female patient. The diagnostic sample obtained from a tru-cut biopsy was a mixed epithelial-mesenchymal tumor with both fetal and embryonal patterns present. In contrast, the post-chemotherapy tumor exhibited a prominent anaplastic large cell population focally reminiscent of pleomorphic hepatocellular carcinoma (HCC). CGH analysis indicated that there were similarities as well as differences in the gains and losses of genetic material in each tumor. The diagnostic sample had gains of chromosome 1q, 2, 2(q31q33), 7, 8q, 12(q15q22), 17q and 20 material, while the post-chemotherapy tumor had gains of 1q, 2, 7, 8q, 10, 17q and 20 material. In addition, the pre- and post-chemotherapy samples may have incurred loss of chromosome 17p material. The main differences between the two samples involved localized gain of 2(q31q33) and 12(q15q22) in the pre-chemotherapy sample, and gain of chromosome 10 material in the post-chemotherapy tumor. The patient subsequently developed metastatic nodules in her lungs, the histology of which was identical in pattern to the diagnostic pattern, and appeared to have localized gain of 2(q31q33) and 12(q15q22). These results are consistent with published results that gain of chromosome 8q and 20 are associated with an unfavorable prognosis.

Coordinate deletion of chromosome 3p and 11q in neuroblastoma detected by comparative genomic hybridization

Neuroblastoma, the most common extracranial solid tumor of childhood, is associated with a number of genetic abnormalities that are prognostically significant. The most common abnormalities are associated with aggressive clinical behavior and include deletion of distal chromosome 1p, NMYC amplification, and unbalanced gain of the long arm of chromosome 17. There are also other recurrent, but less frequent abnormalities, the clinical significance of which is uncertain. These less common abnormalities include deletion 3p, 11q, and 14q. To gain further clinical insight into some of the less commonly observed abnormalities in neuroblastoma, we performed comparative genomic hybridization (CGH) analysis on 24 primary and metastatic neuroblastomas (6 stage 2, 5 stage 3, 11 stage 4, and 2 stage 4). Nineteen of these tumors were prechemotherapy. A total of 190 abnormalities were detected from these tumors. Four of the 24 tumors studied showed loss of 11q material, with 3 of these tumors also possessing distal chromosome 3p deletions. Our results provide confirmation that deletion of chromosome 3p is nonrandomly associated with deletion of chromosome 11q in neuroblastoma. However, analysis of our results, along with other results reported in the literature, indicate that there is no statistically significant association between 3p and 11q loss and more clinically aggressive tumors.

Comparative genomic hybridization in pediatric acute lymphoblastic leukemia

Comparative genomic hybridization (CGH) was used to clarify the chromosomal status of 15 patients diagnosed with childhood acute lymphoblastic leukemia (ALL). Bone marrow samples from 10 of the 15 patients were selected because no metaphases were obtained for cytogenetic analysis. Three patients with normal trypsin and giemsa banding (GTG) karyotypes were also studied by CGH to determine whether significant abnormalities might have been missed by banding analysis, and samples from an additional 2 patients with hyperdiploidy were also included. Seven of the 10 patients with failed GTG banding analysis were found to be chromosomally abnormal by CGH; 2 out of 3 patients with normal GTG band karyotypes were abnormal, indicating that the metaphases available for karyotyping were not malignant cells, and that CGH analysis of hyperdiploid samples provided more accurate resolution than karyotyping alone. The prognostic value of chromosomal aberrations detected by CGII and the efficiency of the technique suggest a central role for CGH in routine clinical cytogenetics.

Applications of comparative genomic hybridisation in constitutional chromosome studies

G band cytogenetic analysis often leads to the discovery of unbalanced karyotypes that require further characterisation by molecular cytogenetic studies. In particular, G band analysis usually does not show the chromosomal origin of small marker chromosomes or of a small amount of extra material detected on otherwise normal chromosomes. Comparative genomic hybridisation (CGH) is one of several molecular approaches that can be applied to ascertain the origin of extra chromosomal material. CGH is also capable of detecting loss of material and thus is also applicable to confirming or further characterising subtle deletions. We have used comparative genomic hybridisation to analyse 19 constitutional chromosome abnormalities detected by G band analysis, including seven deletions, five supernumerary marker chromosomes, two interstitial duplications, and five chromosomes presenting with abnormal terminal banding patterns. CGH was successful in elucidating the origin of extra chromosomal material in 10 out of 11 non-mosaic cases, and permitted further characterisation of all of the deletions that could be detected by GTG banding. CGH appears to be a useful adjunct tool for either confirming deletions or defining their breakpoints and for determining the origin of extra chromosomal material, even in cases where abnormalities are judged to be subtle. We discuss internal quality control measures, such as the mismatching of test and reference DNA in order to assess the quality of the competitive hybridisation effect on the X chromosome.

Electrodiagnostic testing and carpal tunnel release outcome

This study examined the correlation of electrodiagnostic test results and symptom outcome after carpal tunnel release. After meeting specific inclusion and exclusion criteria and failing conservative management, 167 patients (227 hands) underwent an open carpal tunnel release. Of 99 hands with a positive electromyographic/nerve conduction velocity study, 93 (93%) had resolved or improved symptoms. This finding compares with a 93% resolution or improvement rate in 27 hands with a negative electromyographic/nerve conduction velocity study and a 93% resolution or improvement in postoperative symptoms in 101 hands on which no electromyographic/nerve conduction velocity study had been performed. Statistical analysis demonstrated no significant differences in final symptom status after carpal tunnel release when comparing patients who had positive, negative, or no electrodiagnostic preoperative testing. Given specific clinical criteria for establishing the diagnosis of carpal tunnel syndrome, electrodiagnostic testing does not appear to correlate with improved final symptomatic outcome after carpal tunnel release.