Emergence and spread of community-associated methicillin-resistant Staphylococcus aureus in rural Wisconsin, 1989 to 1999

We investigated the emergence and spread of community-associated strains of methicillin-resistant Staphylococcus aureus (CA-MRSA) in central and northern Wisconsin by determining the temporal and clonal relationships and geographic expansion among 581 of 956 clinical isolates of MRSA collected between 1989 and 1999. Based on EcoRI plasmid profiles (PP), two types, PP-11 and PP-13, were highly stable over time and were consistently associated with multidrug-sensitive strains recovered from outpatients treated at Native American community clinics. Pulsed-field gel electrophoresis (PFGE) yielded six major clonal groups (MCGs) and 19 minor clonal groups. The six MCGs represented 82% of the isolates. All strains with either PP-11 or -13 were present in MCG-2. Eighty-nine percent of the isolates in MCG-2 originated from Native American clinics, and 90% belonged to two PFGE types (19 and 20), the types associated with an outbreak of MRSA in a Native American community in 1992. MCG-2 isolates were multidrug sensitive, harbored type IVa staphylococcal cassette chromosome mec, and were very closely related by PFGE to the Midwestern CA-MRSA strain MW2. MCG-2 strains were mostly obtained from skin infections and affected patients with a mean age of 24 (+/-18.0) years. MCG-2 strains spread to four additional Native American communities and 20 other communities. Our findings suggest that CA-MRSA in Wisconsin likely originated in Native American communities in the early 1990s and since has become widespread throughout the state. Two early CA-MRSA strains (WI-33 and WI-34) in Wisconsin represent progenitors of the MW2 strain, based on their almost indistinguishable genotypic characteristics.     

Burn‐McKeown syndrome with biallelic promoter type 2 deletion in TXNL4A in two siblings

Burn‐McKeown syndrome (BMKS) (MIM# 608572) is a rare condition caused by biallelic variants in TXNL4A. BMKS is characterized by craniofacial dysmorphism, choanal atresia, and normal intellect in affected individuals. BMKS has overlapping clinical features with Treacher Collins syndrome. Till date, 15 families have been described with BMKS. Homozygosity or compound heterozygosity of promoter deletions and null variants in TXNL4A are known to cause most cases of BMKS. We describe the first Indian family with two siblings with BMKS and promoter type 2 deletion in homozygous state.     

Evaluation of complete genome sequences and sequences of individual gene products for the classification of hepatitis C viruses

Summary Comparisons of genome and polyprotein sequences of hepatitis C virus (HCV) isolates world-wide has led to the identification of nine major genotypes and many subtypes. This classification is based on either complete genome/polyprotein sequences or sequence data from the 5 noncoding region, core, E1, NS3 or NS5B genes. The relative merit of different gene segments as taxonomic markers and the validity of the resulting assignments is not clear at this stage. To resolve the taxonomy of HCV genotypes and subtypes, we have compared the complete genome and polyprotein sequences of 19 HCV isolates available in the databases as well as sequences of individual genes and gene products of these isolates. Based on the correlation between sequence relationships and taxonomic assignments of other RNA viruses, we show that the nine major genotypes of HCV represent nine distinct virus species and their subtypes subspecies. Our sequence comparison of the 5 noncoding regions and the individual gene products suggests that E2, NS2, NS5B, E1, NS4A, NS4B and NS5A (in that order) are the most appropriate regions for the discrimination between species, subspecies and strains of HCV. The 5 noncoding, core and NS3 regions are less effective in distinguishing between species, subspecies and strains. Based on a comparison of the polymerase sequence identities of HCVs, pestiviruses and flaviviruses as well as the recent information on the size and morphology of HCV virions, we propose that HCVs, pestiviruses and flaviviruses should be classified into three separate families, namedHepciviridae, Pestiviridae andFlaviviridae, respectively rather than three genera of theFlaviviridae as currently classified. We also propose Hepcivirus as the genus name for HCVs.     

Immunology: Outcome of pregnancy in women with recurrent spontaneous abortion following immunotherapy with allogeneic lymphocytes

The efficacy of immunotherapy in the prevention of habitualabortion remains controversial. It has been suggested that thebenefits are predominantly due to psychological factors. Wehave evaluated the success of pregnancy outcome following immunotherapywith allogeneic lymphocytes, in relation to the subsequent developmentof anti-paternal cytotoxic antibodies (APCA). It was observedthat in women who developed an APCA titre of 1:16, live birthsoccurred in 16 out of 21 cases (76%), while only two out ofseven (28%) women who failed to achieve an APCA titre of 1:16had successful pregnancies (P <0.05). In eight women whohad an APCA titre of 1: 16 on initial screening, and were, therefore,excluded from the trial, successful pregnancy outcome was notedin 62.5% of cases. Although these results are based on a smallsample and on an open, non-randomized trial, they show thatthe efficacy of immunotherapy is related to immune responseto allogeneic lymphocytes, and is not simply a placebo effect.Measurement of APCA titre could serve as a marker for immunopotentiation.     

Differentiation of potyviruses and their strains by hybridization with the 3' non-coding region of the viral genome.

Nucleic acid hybridization with the 3' non-coding region of the potyvirus genome as the probe was shown to be a relatively simple means of distinguishing between distinct potyviruses and their strains. Comparisons of the nucleotide sequences of potyvirus genomes (ignoring gaps) showed that the degree of identity between equivalent genes of strains was greater than 96%, while between distinct potyviruses the identity ranged from 42% to 65%, suggesting that any extended sequence could be considered representative of the whole genome and be suitable as a diagnostic probe. The comparisons however, also revealed that some parts of the genome, but not the 3' non-coding region, had local regions of high sequence identity that could lead to cross-hybridization between distinct potyviruses. For this reason, and because its location immediately upstream of the poly(A) tail makes it the most accessible region for the purpose of cloning and sequencing, the 3' non-coding sequence should be most suitable for use as a diagnostic probe. Successful hybridizations (using radiolabeled, polymerase chain reaction-amplified 3' non-coding sequences) have been achieved by probing recombinant clones, purified potyviral RNA, partially purified total RNA from infected plants, and a crude extract of infected plant tissue. The method has been used to support the proposals that watermelon mosaic virus 2 and soybean mosaic virus-N are both strains of the same virus, and to discriminate between several isolates previously believed to be strains of sugarcane mosaic virus. The method should have wide application as a means of differentiating distinct potyviruses from strains.     

Aqueous polymerization of acrylamide initiated by acidic permanganate/thiourea redox system

The polymerization of acrylamide, initiated by acidic permanganate/thiourea redox system, was studied in aqueous media at 30 ± 0,2 °C in nitrogen. The rate of polymerization (R_p) was found to be proportional to nearly the first power of the catalyst (KMnO₄) concentration, within the range of 0,5 · 10^?2 to 1,4 · 10^?2 mol dm^?3, and independent of the thiourea concentration. However, the rate of polymerization varies with the first power of the hydrochloric acid concentration within the range of 2,85 · 10^?2 to 11,4 · 10^?2 mol dm^?3, and increases linearly up to certain extent by varying the monomer concentration from 2,5 · 10^?2 to 12,5 · 10^?2 mol dm^?3. A deviation from the linear behaviour is observed, however, above a concentration of 12,5 · 10^?2 mol dm^?3. The initial rate of polymerization (R_i) as well as the maximum conversion increases by increasing the temperature up to 35 °C, but the maximum conversion falls as the temperature rises above 35 °C. The overall energy of activation is found to be 47,70 kJ mol^?1 (11,48 kcal/mol^?1) within the temperature range of 25–45 °C. Addition of salts, except manganous salts, was found to be associated with a depression in the R_p and maximum conversion. The effect of cationic and anionic surfactants has been found to increase and decrease the R_p respectively; non-ionic detergents, however, have no effect on the R_p.     

Chest wall metastases from unknown primary hepatocellular carcinoma

Metastases of hepatocellular carcinoma (HCC) to the bones are common but bone metastases of hepatocellular carcinoma in the presence of a normal liver are an uncommon entity. A 50-year-old male patient presented with a rapidly growing tumour on the sternum. Biopsy of the lesion showed metastatic sternal tumour from a primary hepatocellular carcinoma. Radiological evaluation however, failed to detect a primary lesion in the liver. Bone metastases of hepatocellular carcinoma localized to the chest wall in the presence of a normal liver are scarcely reported as anecdotal case reports in the literature.