Light-chain amyloidosis (AL) is a plasma cell dyscrasia closely related to multiple myeloma. In multiple myeloma, the cancer-testis antigens (CTAs) CT7 (MAGE-C1), CT10 (MAGE-C2) and MAGE-A CTAs are expressed in up to 80% of cases. In this study, we investigated the expression and immunogenicity of several CTAs in patients with AL amyloidosis in a total of 38 bone marrow specimens by employing standard immunohistochemistry techniques on paraffin-embedded archival tissues. Plasma samples from 35 patients (27 with matched bone marrow samples) were also analyzed by ELISA for sero reactivity to a group of full-length CTA proteins. CT7 was present in 25/38 (66%) while CT10 was demonstrated in 3/38 and GAGE in 1/38 AL amyloid cases. The expression pattern was mostly focal. There were no significant differences with regard to organ involvement, response to treatment, or prognosis in CTA positive compared to negative cases. None of the specimens showed spontaneous humoral immunity to CT7, but sero reactivity was observed in individual patients to other CTAs. This study identifies CT7 as the prevalent CTA in plasma cells of patients with AL amyloidosis. Further analyses determining the biology of CTAs in AL amyloidosis and their value as potential targets for immunotherapy are warranted.

INTRODUCTION

The Lachman test is commonly performed as part of the routine assessment of patients with suspected anterior cruciate ligament (ACL) deficiency. A major drawback is its reliance on the clinician's subjective judgement of movement. The aim of this study was to quantify Lachman movement using a magnetic tracking device thereby providing a more accurate objective measure of movement.

PATIENTS AND METHODS

Ten patients aged 21–51 years were assessed as having unilateral ACL deficiency with conventional clinical tests. These patients were then re-assessed using a Polhemus Fastrak™ magnetic tracking device.

RESULTS

The mean anterior tibial displacement was 5.6 mm (SD = 2.5) for the normal knees and 10.2 mm (SD = 4.2) for the ACL-deficient knees. This gave an 82% increase in anterior tibial displacement for the ACL deficient knees. This was shown to be highly significant with P = 0.005.

CONCLUSIONS

The magnetic tracking system offers an objective quantification of displacements during the Lachman test. It is convenient, non-invasive and comfortable for the patient and is, therefore, ideally suited for use as an investigative tool.

A strain of an Enterobacter sp. with reduced susceptibility to imipenem, which produced a plasmid-mediated class A carbapenem-hydrolyzing enzyme, KPC-2 β-lactamase, was isolated from a patient with sepsis at a Boston hospital. This is the first report of the production of a plasmid-encoded KPC-2 β-lactamase by an Enterobacter sp.

Detection of extended-spectrum β-lactamases (ESBLs) in AmpC-producing Enterobacteriaceae is problematic. A modification of the double-disk test (MDDT) has been developed for successful detection of ESBLs in gram-negative bacilli producing well-characterized β-lactamases as well as 212 clinical isolates of Enterobacter cloacae, Enterobacter aerogenes, Serratia marcescens, and Citrobacter freundii. MDDT accurately differentiated between ESBL producers and derepressed chromosomal AmpC mutants. MDDT provides a cost-effective alternative approach for clinical microbiology laboratories for routine susceptibility testing with simultaneous detection of ESBLs in Enterobacteriaceae.

Although resistance to the expanded-spectrum cephalosporins among members of the family Enterobacteriaceae lacking inducible β-lactamases occurs virtually worldwide, little is known about this problem among isolates recovered in South Africa. Isolates of Klebsiella pneumoniae, Escherichia coli, and Proteus mirabilis resistant to expanded-spectrum cephalosporins recovered from patients in various parts of South Africa over a 3-month period were investigated for extended-spectrum β-lactamase production. Antibiotic susceptibility was determined by standard disk diffusion and agar dilution procedures. Production of extended-spectrum β-lactamases was evaluated by using the double-disk test, and the β-lactamases were characterized by spectrophotometric hydrolysis assays and an isoelectric focusing overlay technique which simultaneously determined isoelectric points and general substrate or inhibitor characteristics. DNA amplification and sequencing were performed to confirm the identities of these enzymes. The P. mirabilis and E. coli isolates were found to produce TEM-26-type, SHV-2, and SHV-5 extended-spectrum β-lactamases. An AmpC-related enzyme which had a pI of 8.0 and which conferred resistance to cefoxitin as well as the expanded-spectrum cephalosporins was found in a strain of K. pneumoniae. This is the first study which has identified organisms producing different extended-spectrum β-lactamases from South Africa and the first report describing strains of P. mirabilis producing a TEM-26-type enzyme. The variety of extended-spectrum β-lactamases found among members of the family Enterobacteriaceae isolated from major medical centers in South Africa is troubling and adds to the growing list of countries where these enzymes pose a serious problem for antimicrobial therapy.

Parvovirus protein NS1 is required for replication of viral DNA and plays a role in the regulation of viral gene expression. NS1 trans-activates the P38 promoter for capsid protein synthesis and has variable effects on other promoters. In this study, we examined the effects of NS1 on the regulation of its own promoter, P4. A number of plasmid constructions were made with the P4 promoter fused to reporter genes. The effects of NS1 on expression from the P4 promoter differed depending on the construction. Plasmids containing viral sequences which could not replicate showed a decrease in P4 expression on cotransfection with the NS1 gene. However, plasmids having replication-proficient viral sequences showed a three- to fivefold increase in P4 expression dependent on NS1. The effect on NS1 on P4 transcription was also evaluated at the steady-state RNA level. An infectious clone of the LuIII viral genome was modified to an NS1-NS2 null mutant (pLu272) that is competent for viral DNA replication by introducing a frameshift mutation at codon 5 of the NS1 open reading frame. The P4 transcripts of pLu272 are four nucleotides longer than the wild type and can therefore be resolved from the wild type by primer extension analysis. pLu272 allows comparison of the constitutive level of steady-state RNA produced by the pLu272 P4 promoter in the absence or presence of a template replication dependent on NS1 supplied in trans. NS1 increased P4 transcripts about six- to eightfold. Expression of P4 transcripts from clones that could not amplify depended on the presence of an intact inverted terminal repeat sequence at the left end. A clone with an intact viral left end and a defective viral right end gave an NS1-dependent threefold increase in P4 expression. Destruction of terminal hairpins at both ends resulted in no significant increase in P4 expression in the presence of NS1. Thus, the positive effect of NS1 on the steady-state levels of P4 transcripts depends on the amplification of gene copy number and the integrity of the terminal repeats.

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