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At least 451 records · Page 25Linked to original sources
PubMed1982

Role of lymphatic vessels in bacterial clearance from early soft-tissue infection.

A popular concept regarding the pathophysiologic characteristics of infection is that early bacterial clearance from tissue is an important host defense mechanism. Staphylococcus aureus, S epidermidis, Escherichia coli, enterococcus, and Klebsiella pneumoniae were radiolabeled with tritiated thymidine and injected subcutaneously into rabbit ears. Negligible clearance occurred at five hours, and less than 30% of injected bacteria cleared in 24 hours. Lymphatic function measured by clearance with bovine serum albumin labeled with iodine 125 was normal at all times during the first 24 hours. Clearance of live S aureus, radiolabeled by tritiated thymidine, was not accelerated by preexisting 12- or 24-hour hold-old inflammatory lesions. Clearance of bacteria rendered nonviable in vitro by antibiotics and heat were cleared in proportion to the degree of bacterial cell lysis. Bacterial clearance of S aureus correlated with the rate of bacterial lysis by polymorphonuclear leukocytes in vitro. These data support the hypothesis that lymphatic clearance of bacteria from soft tissues is of negligible importance as a host defense mechanism in the decisive period of soft-tissue infection.

Animals↗
PubMed2002

A mass balance study to assess the extent of contaminant removal achieved in the operations for the primary recovery of plasmid DNA from Escherichia coli cells.

Mass balances were performed on an alkaline lysis operation for the primary recovery of supercoiled plasmid DNA as part of a process for plasmid gene preparation. Escherichia coli DH5alpha/pSVbeta was cultured in defined medium by fed-batch fermentation and harvested at the end of the exponential phase. Alkaline lysis of the recombinant cells was performed at fixed shear rates ranging between 46 and 461 s(-1), with neutralization 100 and 300 s after the initiation of the lysis. Mass balance calculations were used to optimize the operating conditions for carrying out the alkaline lysis operation. The results indicated that a plasmid yield of 75% and purity with respect to total DNA of 60% were achievable during the primary recovery operation. The influences of key contaminants, including the soluble proteins and the suspended solids, as they bear on the subsequent purification operations, were evaluated and discussed.

Bacteriolysis↗
PubMed2005

Immobilized N-alkylated polyethylenimine avidly kills bacteria by rupturing cell membranes with no resistance developed.

Several critical mechanistic and phenomenological aspects of the microbicidal surface coatings based on immobilized hydrophobic polycations, previously developed by us, are addressed. Using Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria, remarkable bactericidal action (up to a 10(9)-fold reduction in live bacteria count in the surface-exposed solution and a 100% inactivation of the surface-adhered bacteria) of an amino-glass slide covalently derivatized with N-hexyl,methyl-polyethylenimine (PEI) is found to be due to rupturing bacterial cell membranes by the polymeric chains. The bacteria fail to develop noticeable resistance to this lethal action over the course of many successive generations. Finally, the immobilized N-alkyl-PEI, while deadly to bacteria, is determined to be harmless to mammalian (monkey kidney) cells.

Animals↗
PubMed1983

The lysis function of RNA bacteriophage Qbeta is mediated by the maturation (A2) protein.

Complete or partial cDNA sequences of the RNA bacteriophage Qbeta were cloned in plasmids under the control of the lambdaP(L) promoter to allow regulated expression in Escherichia coli harbouring the gene for the temperature-sensitive lambdaCI857 repressor. Induction of the complete Qbeta sequence leads to a 100-fold increase in phage production, accompanied by cell lysis. Induction of the 5'-terminal sequence containing the intact maturation protein (A2) cistron also causes cell lysis. Alterations of the A2 cistron, leading to proteins either devoid of approximately 20% of the C-terminal region or of six internal amino acids, abolish the lysis function. Expression of other cistrons in addition to the A2 cistron does not enhance host lysis. Thus, in Qbeta, the A2 protein, in addition to its functions as maturation protein, appears to trigger cell lysis. This contrasts with the situation in the distantly related group I RNA phages such as f2 and MS2 where a small lysis polypeptide is coded for by a region overlapping the end of the coat gene and the beginning of the replicase gene.

Allolevivirus↗
PubMed1985

The amino terminal half of the MS2-coded lysis protein is dispensable for function: implications for our understanding of coding region overlaps.

We have asked whether genetic overlaps only evolve to provide extra coding capacity in genomes of restricted size. As a model system we have used the lysis gene of the RNA bacteriophage MS2. This gene overlaps with the distal part of the coat protein gene and with the proximal part of the replicase gene. Using recombinant DNA procedures we have determined whether either of the two overlaps codes for amino acids that are not essential for the function of the 75 amino acid long lysis protein. We find that the first 40 amino acids of the lysis protein are dispensable for function. Thus all of the genetic information essential to the synthesis of the active C-terminal peptide lies within the overlap with the replicase gene, whereas all dispensable residues are encoded in the overlap with the coat protein gene and in the intercistronic region. This suggests that the overlap with the coat protein gene is not required for extra coding capacity but serves to regulate the expression of the lysis gene. Comparative sequence analysis is consistent with this idea.

Amino Acid Sequence↗