Murine C4-binding protein: a rapid purification method by affinity chromatography

A simple, 3-step method was described for purification of murine C4 binding protein (C4-bp), a recently recognized serum protein that functions as one of the regulatory proteins of the complement system. The method consists of 1) affinity chromatography using TNBS-BGG-conjugated Sepharose beads, 2) gel filtration on a Sepharose 6B column, and 3) heparin-Sepharose chromatography. By this method, milligram quantities of C4-bp can be easily purified by more than 500-fold from EDTA-serum of various mouse strains, and the whole purification process can be completed within 1 wk. The overall yield of C4-bp is about 15%. The C4-bp thus prepared is homogeneous as judged by SDS-polyacrylamide gel electrophoresis and immunelectrophoresis. The purified mouse C4-bp showed physicochemical properties very similar to those described for human C4-bp. Like human C4-bp, mouse C4-bp is composed of several apparently identical subunits of the m.w. of 80,000. However unlike the human counterpart, the subunits of mouse C4-bp are not linked by disulfide bonds but are connected by non-covalent forces that can be disrupted by SDS. The purified mouse C4-bp retained binding affinity for C4 and showed unaltered antigenicity. Immunization of rabbits with the purified mouse C4-bp resulted in the production of potent and monospecific antisera.     

Production of tetanolysin preparations and characteristics of their properties

As the result of the study of tetanolysin-producing Clostridium tetani strains, their populations have been found to be markedly heterogeneous with respect to the hemolytic activity of clone cultures. On the basis of normal and dialyzed cultures of selected variants with maximum activity the preparations of tetanolysin have been obtained, and their hemolytic activity and antigenic properties have been studied. Antihemolytic rabbit sera have also been obtained and characterized. Partially purified preparations of tetanolysin with high hemolytic activity have been obtained by the fractionation of C. tetani dialyzed cultures with ammonium sulfate.     

Cloning and expression of the Erwinia chrysanthemi asparaginase gene in Escherichia coli and Erwinia carotovora

A genomic library of Erwinia chrysanthemi DNA was constructed in bacteriophage lambda 1059 and recombinants expressing Er. chrysanthemi asparaginase detected using purified anti-asparaginase IgG. The gene was subcloned on a 4.7 kb EcoRI DNA restriction fragment into pUC9 to generate the recombinant plasmid pASN30. The position and orientation of the asparaginase structural gene was determined by subcloning. The enzyme was produced at high levels in Escherichia coli (5% of soluble protein) and was shown to be exported to the periplasmic space. Purified asparaginase from E. coli cells carrying pASN30 was indistinguishable from the Erwinia enzyme on the basis of specific activity [660-700 units (mg protein)-1], pI value (8.5), and subunit molecular weight (32 X 10(3]. Expression of the cloned gene was subject to glucose repression in E. coli but was not significantly repressed by glycerol. Recombinant plasmids, containing the asparaginase gene, when introduced into Erwinia carotovora, caused increased synthesis of the enzyme (2-4 fold higher than the current production strain).     

Isolation of mutants of the obligate methanotroph Methylomonas albus defective in growth on methane

A strain of Methylomonas albus BG8WM, a type 1 obligate methanotroph, which had been maintained for 2 ycars by serial passage on solid medium containing methanol as a carbon source was found to mutate at a frequency of 10^-5-10^-6 to resistance to dichloromethane (DCM^R), the parental strain BG8 did not give rise to DCM^R colonies. DCM^R strains were no longer capable of growth on methane as a carbon cource and exhibited greatly reduced or undetectable methane mono-oxygenase activity. The mutants fell into three groups on the basis of SDS-PAGE analysis of the polypeptide profiles of the particulate fraction of cell extracts. One or more of four polypeptides of Mr 70,000, 50,000, 25,000 and 23,000 were implicated as being components of the methane mono-oxygenase. Spontaneous reversion to growth on methane and sensitivity to dichloromethane occurred at a frequency of about 10^-8. The loss of methane mono-oxygenase activity was not associated with loss of the resident 55 kb plasmid.Abbreviations DCM^R dichloromethane-resistant - SDS-PAGE sodium dodecyl sulphate polyacrylamide gel electrophoresis - NMS nitrate minimal salts medium     

Increased near-ultraviolet induced DNA fragmentation in xeroderma pigmentosum variants.

Immediate fragmentation of parental DNA by near-ultraviolet irradiation at 313 nm was measured in cultured skin fibroblasts from normal individuals, patients with Xeroderma pigmentosum of complementation group A (XPA) and Xeroderma pigmentosum variants (XPV) by the alkaline elution procedure. For a dose of 2.25 KJm^?2 given at O^o fragmentation was comparable in all cell strains. However, fragmentation was strongly increased relative to O^o in XPV but not in normal fibroblasts and the XPA strains when irradiation was carried out at 37^o. From our results it appears that a step in the repair of $\text{parental}$ DNA is abnormal in XPV.     

Different Risk of Tuberculosis and Efficacy of Isoniazid Prophylaxis in Rheumatoid Arthritis Patients with Biologic Therapy: A Nationwide Retrospective Cohort Study in Taiwan

Increasing evidence indicates an increased risk of tuberculosis (TB) for rheumatoid arthritis (RA) patients receiving biologic therapy, and the effectiveness of isoniazid prophylaxis (INHP) in TB prevention. We aimed to examine 1) the incidence rate (IR) and risk factors for TB among RA patients receiving different therapies; 2) INHP effectiveness for TB prevention; 3) mortality rates after TB diagnosis in patients receiving different therapies. This retrospective study was conducted using a nationwide database: 168,720 non-RA subjects and a total of 42,180 RA patients including 36,162 csDMARDs-exposed, 3,577 etanercept-exposed, 1,678 adalimumab-exposed and 763 rituximab-exposed patients. TB risk was 2.7-fold higher in RA cohort compared with non-RA group, with an adjusted hazard ratio (aHR) of 2.58. Advanced age, male, the use of corticosteroids≧5mg/day, and the presence of diabetes mellitus (DM), chronic obstructive pulmonary disease and chronic kidney disease were risk factors for developing TB. Using csDMARDs-exposed group as reference, aHR of TB was the highest with adalimumab treatment (1.52), followed by etanercept (1.16), and the lowest with rituximab (0.08). INHP could effectively reduce TB risk in biologics-exposed patients. Mortality rates after TB diagnosis were higher in RA patients, particularly the elderly and those with DM, with lower rates in adalimumab-exposed patients compared with csDMARDs-exposed patients. In conclusion, TB risk was increased in patients receiving TNF-α inhibitors, but the risk associated with rituximab therapy was relatively low. With the effectiveness of INHP shown in the prevention of biologics-associated TB, stricter implementation of INHP should be beneficial. The mortality from biologics–associated TB may be efficiently reduced through increased awareness.