Unusual presentation of choriocarcinoma

Background  

Choriocarcinoma is an aggressive neoplasm arising in the body of the uterus. The disease normally spreads to lung and brain.     

Differential expression level of cytokeratin 8 in cells of the bovine nucleus pulposus complicates the search for specific intervertebral disc cell markers

Introduction  

Development of cell therapies for repairing the intervertebral disc is limited by the lack of a source of healthy human disc cells. Stem cells, particularly mesenchymal stem cells, are seen as a potential source but differentiation strategies are limited by the lack of specific markers that can distinguish disc cells from articular chondrocytes.     

Saccharomyces cerevisiae MSH2-MSH3 and MSH2-MSH6 complexes display distinct requirements for DNA binding domain I in mismatch recognition

In eukaryotic mismatch repair (MMR) MSH2-MSH6 initiates the repair of base-base and small insertion/deletion mismatches while MSH2-MSH3 repairs larger insertion/deletion mismatches. Here, we show that the msh2Delta1 mutation, containing a complete deletion of the conserved mismatch recognition domain I of MSH2, conferred a separation of function phenotype with respect to MSH2-MSH3 and MSH2-MSH6 functions. Strains bearing the msh2Delta1 mutation were nearly wild-type in MSH2-MSH6-mediated MMR and in suppressing recombination between DNA sequences predicted to form mismatches recognized by MSH2-MSH6. However, these strains were completely defective in MSH2-MSH3-mediated MMR and recombination functions. This information encouraged us to analyze the contributions of domain I to the mismatch binding specificity of MSH2-MSH3 in genetic and biochemical assays. We found that domain I in MSH2 contributed a non-specific DNA binding activity while domain I of MSH3 appeared important for mismatch binding specificity and for suppressing non-specific DNA binding. These observations reveal distinct requirements for the MSH2 DNA binding domain I in the repair of DNA mismatches and suggest that the binding of MSH2-MSH3 to mismatch DNA involves protein-DNA contacts that appear very different from those required for MSH2-MSH6 mismatch binding.     

Mismatch repair factor MSH2-MSH3 binds and alters the conformation of branched DNA structures predicted to form during genetic recombination

Genetic studies in Saccharomyces cerevisiae predict that the mismatch repair (MMR) factor MSH2-MSH3 binds and stabilizes branched recombination intermediates that form during single strand annealing and gene conversion. To test this model, we constructed a series of DNA substrates that are predicted to form during these recombination events. We show in an electrophoretic mobility shift assay that S. cerevisiae MSH2-MSH3 specifically binds branched DNA substrates containing 3' single-stranded DNA and that ATP stimulates its release from these substrates. Chemical footprinting analyses indicate that MSH2-MSH3 specifically binds at the double-strand/single-strand junction of branched substrates, alters its conformation and opens up the junction. Therefore, MSH2-MSH3 binding to its substrates creates a unique nucleoprotein structure that may signal downstream steps in repair that include interactions with MMR and nucleotide excision repair factors.     

Msh2-Msh3 interferes with Okazaki fragment processing to promote trinucleotide repeat expansions

Trinucleotide repeat (TNR) expansions are the underlying cause of more than 40 neurodegenerative and neuromuscular diseases, including myotonic dystrophy and Huntington's disease. Although genetic evidence points to errors in DNA replication and/or repair as the cause of these diseases, clear molecular mechanisms have not been described. Here, we focused on the role of the mismatch repair complex Msh2-Msh3 in promoting TNR expansions. We demonstrate that Msh2-Msh3 promotes CTG and CAG repeat expansions in vivo in Saccharomyces cerevisiae. Furthermore, we provide biochemical evidence that Msh2-Msh3 directly interferes with normal Okazaki fragment processing by flap endonuclease1 (Rad27) and DNA ligase I (Cdc9) in the presence of TNR sequences, thereby producing small, incremental expansion events. We believe that this is the first mechanistic evidence showing the interplay of replication and repair proteins in the expansion of sequences during lagging-strand DNA replication.     

Frequent Seizures Are Associated with a Network of Gray Matter Atrophy in Temporal Lobe Epilepsy with or without Hippocampal Sclerosis

Objective

Patients with temporal lobe epilepsy (TLE) with hippocampal sclerosis (HS) have diffuse subtle gray matter (GM) atrophy detectable by MRI quantification analyses. However, it is not clear whether the etiology and seizure frequency are associated with this atrophy. We aimed to evaluate the occurrence of GM atrophy and the influence of seizure frequency in patients with TLE and either normal MRI (TLE-NL) or MRI signs of HS (TLE-HS).

Methods

We evaluated a group of 172 consecutive patients with unilateral TLE-HS or TLE-NL as defined by hippocampal volumetry and signal quantification (122 TLE-HS and 50 TLE-NL) plus a group of 82 healthy individuals. Voxel-based morphometry was performed with VBM8/SPM8 in 3T MRIs. Patients with up to three complex partial seizures and no generalized tonic-clonic seizures in the previous year were considered to have infrequent seizures. Those who did not fulfill these criteria were considered to have frequent seizures.

Results

Patients with TLE-HS had more pronounced GM atrophy, including the ipsilateral mesial temporal structures, temporal lobe, bilateral thalami and pre/post-central gyri. Patients with TLE-NL had more subtle GM atrophy, including the ipsilateral orbitofrontal cortex, bilateral thalami and pre/post-central gyri. Both TLE-HS and TLE-NL showed increased GM volume in the contralateral pons. TLE-HS patients with frequent seizures had more pronounced GM atrophy in extra-temporal regions than TLE-HS with infrequent seizures. Patients with TLE-NL and infrequent seizures had no detectable GM atrophy. In both TLE-HS and TLE-NL, the duration of epilepsy correlated with GM atrophy in extra-hippocampal regions.

Conclusion

Although a diffuse network GM atrophy occurs in both TLE-HS and TLE-NL, this is strikingly more evident in TLE-HS and in patients with frequent seizures. These findings suggest that neocortical atrophy in TLE is related to the ongoing seizures and epilepsy duration, while thalamic atrophy is more probably related to the original epileptogenic process.     

Allergy to penicillin: fable or fact?

OBJECTIVE--To assess whether, on the basis of one blood test, penicillin allergy might be excluded sufficiently for general practitioners to give oral penicillin to patients claiming a history of penicillin allergy. DESIGN--Prospective study of patients referred by general practitioners. SETTING--Outpatient allergy clinic in a district general hospital. PATIENTS--175 referred patients who gave a history of immediate type reaction to penicillin, of whom 144 attended as requested and 132 completed the investigations. MAIN OUTCOME MEASURES--History and examination, serum radioallergosorbent test to phenoxymethylpenicillin and benzylpenicillin, and oral challenge with penicillin. RESULTS--Of 132 patients, four were confirmed to have penicillin allergy by the radioallergosorbent test and 128 had an oral penicillin challenge without ill effect. CONCLUSIONS--Most patients who gave a history of penicillin allergy are not so allergic, and their actual allergic state should be substantiated whenever feasible. For patients reporting minor or vague reactions negative findings with a radioallergosorbent test to phenoxymethylpenicillin and benzylpenicillin provide sufficient evidence to give oral penicillin safely.     

Structure, Function, and Evolution of the Crimean-Congo Hemorrhagic Fever Virus Nucleocapsid Protein

Crimean-Congo hemorrhagic fever virus (CCHFV) is an emerging tick-borne virus of the Bunyaviridae family that is responsible for a fatal human disease for which preventative or therapeutic measures do not exist. We solved the crystal structure of the CCHFV strain Baghdad-12 nucleocapsid protein (N), a potential therapeutic target, at a resolution of 2.1 Å. N comprises a large globular domain composed of both N- and C-terminal sequences, likely involved in RNA binding, and a protruding arm domain with a conserved DEVD caspase-3 cleavage site at its apex. Alignment of our structure with that of the recently reported N protein from strain YL04057 shows a close correspondence of all folds but significant transposition of the arm through a rotation of 180 degrees and a translation of 40 Å. These observations suggest a structural flexibility that may provide the basis for switching between alternative N protein conformations during important functions such as RNA binding and oligomerization. Our structure reveals surfaces likely involved in RNA binding and oligomerization, and functionally critical residues within these domains were identified using a minigenome system able to recapitulate CCHFV-specific RNA synthesis in cells. Caspase-3 cleaves the polypeptide chain at the exposed DEVD motif; however, the cleaved N protein remains an intact unit, likely due to the intimate association of N- and C-terminal fragments in the globular domain. Structural alignment with existing N proteins reveals that the closest CCHFV relative is not another bunyavirus but the arenavirus Lassa virus instead, suggesting that current segmented negative-strand RNA virus taxonomy may need revision.