Hepatic breast cancer dissemination after an iatrogenic hepatic laceration during talc pleurodesis: a case report

<p>Abstract</p> <p>Background</p> <p>Talc pleurodesis is an effective treatment for malignant pleural effusion. We present a case of an asymptomatic hepatic laceration that occurred during pleurodesis in a breast cancer patient and led to hepatic tumor dissemination.</p> <p>Discussion</p> <p>Pleurodesis is a relatively safe procedure, although previous studies have described malignant invasion of scar tissue.</p> <p>Conclusion</p> <p>To our knowledge, this is the first case report of tumor spread due to a liver puncture during talc pleurodesis in a breast cancer patient.</p

Isolation of the membrane-bound 26 000-Mr penicillin-binding protein of Streptomyces strain K15 in the form of a penicillin-sensitive D-alanyl-D-alanine-cleaving transpeptidase.

The membrane-bound, 26 000-Mr penicillin-binding protein of Streptomyces K15 has been isolated in the form of an effective, penicillin-sensitive D-alanyl-D-alanine-cleaving peptidase exhibiting high transpeptidase activity (greater than 95%) and very low carboxy-peptidase activity (less than 5%). The penicillin-binding protein/transpeptidase can be extracted directly from the mycelium with N-cetyl-NNN-trimethylammonium bromide (Cetavlon) and subsequently obtained at 90% purity and with an 8000-fold specific enrichment (when compared with the activity of the isolated membranes) by a two-step procedure involving Sephadex filtration and affinity chromatography on ampicillin-linked CH Sepharose 4B in the presence of detergent. At saturating concentrations of the co-substrates diacetyl-L-Lys-D-Ala-D-Ala and Gly-Gly, the catalytic-centre activity is about 0.3 s-1

Effects of thiol reagents on Streptomyces K15 DD-peptidase-catalysed reactions.

The 26,000-Mr DD-peptidase of Streptomyces K15 binds one equivalent of thiol reagents as 5,5'-dithiobis-(2-nitrobenzoate) or p-chloromercuribenzoate (pCMB). Derivatization of the DD-peptidase by pCMB decreases the efficacy of the initial binding of the ester carbonyl donor Ac2-L-Lys-D-Ala-D-lactate to the enzyme (K), the rate of enzyme acylation by the donor (K+2) and the rate of enzyme deacylation (k+3). However, the value of the k+2/k+3 ratio, and therefore the percentage of total enzyme which, at saturating concentrations of the donor, is present as acyl-enzyme at the steady state of the reaction, are not modified. The enzyme's binding sites for pCMB and benzylpenicillin are not mutually exclusive. But, when compared with the native enzyme, the pCMB-derivatized enzyme undergoes acylation by benzylpenicillin with a decreased second-order-rate constant (k+2/K) value and gives rise to a penicilloyl adduct of increased stability. Since the acyl-enzyme mechanism is not annihilated by pCMB derivatization, it is proposed that basically, and like all the other DD-peptidases/penicillin-binding proteins so far characterized, the Streptomyces K15 DD-peptidase is an active-site-serine enzyme

Streptomyces K15 active-site serine DD-transpeptidase: specificity profile for peptide, thiol ester and ester carbonyl donors and pathways of the transfer reactions.

The Streptomyces K15 transferase is a penicillin-binding protein presumed to be involved in bacterial wall peptidoglycan crosslinking. It catalyses cleavage of the peptide, thiol ester or ester bond of carbonyl donors Z-R1-CONH-CHR2-COX-CHR3-COO- (where X is NH, S or O) and transfers the electrophilic group Z-R1-CONH-CHR2-CO to amino acceptors via an acyl-enzyme intermediate. Kinetic data suggest that the amino acceptor behaves as a simple alternative nucleophile at the level of the acyl-enzyme in the case of thiol ester and ester donors, and that it binds to the enzyme.carbonyl donor Michaelis complex and influences the rate of enzyme acylation by the carbonyl donor in the case of amide donors. Depending on the nature of the scissile bond, the enzyme has different requirements for substituents at positions R1, R2 and R3

Streptomyces K15 DD-peptidase-catalysed reactions with ester and amide carbonyl donors.

In water, the purified 26 000-Mr membrane-bound DD-peptidase of Streptomyces K15 hydrolyses the ester carbonyl donor Ac2-L-Lys-D-Ala-D-lactate (release of D-lactate) and the amide carbonyl donor Ac2-L-Lys-D-Ala-D-Ala (release of D-alanine) with accumulation of acyl- (Ac2-L-Lys-D-alanyl-)enzyme. Whereas hydrolysis of the ester substrate proceeds to completion, hydrolysis of the amide substrate is negligible because of the capacity of the K15 DD-peptidase for utilizing the released D-alanine in a transfer reaction (Ac2-L-Lys-D-Ala-D-Ala + D-Ala----Ac2-L-Lys-D-Ala-D-Ala + D-Ala) that maintains the concentration of the amide substrate at a constant level. In the presence of an amino acceptor X-NH2 (Gly-Gly or Gly-L-Ala) related to the Streptomyces peptidoglycan, both amide and ester carbonyl donors are processed without detectable accumulation of acyl-enzyme. Under proper conditions, the acceptor activity of water and, in the case of the amide substrate, the acceptor activity of the released D-alanine can be totally overcome so that the two substrates are quantitatively converted into transpeptidated product Ac2-L-Lys-D-Ala-NH-X (and hydrolysis is prevented). Experimental evidence suggests that the amino acceptor modifies both the binding of the carbonyl donor to the enzyme and the ensuing rate of enzyme acylation

The non-penicillin-binding module of the tripartite penicillin-binding protein 3 of Escherichia coli is required for folding and/or stability of the penicillin-binding module and the membrane-anchoring module confers cell septation activity on the folded structure.

The ftsI-encoded multimodular class B penicillin-binding protein 3 (PBP3) is a key element of the cell septation machinery of Escherichia coli. Altered ftsI genes were overexpressed, and the gene products were analyzed with respect to the level of production, stability, penicillin affinity, and cell septation activity. In contrast to the serine beta-lactamases and low-molecular-mass PBPs which are autonomous folding entities, the S-259-to-V-577 penicillin-binding module of M-1-to-V-577 PBP3 lacks the amino acid sequence information for correct folding. The missing piece of information is provided by the associated G-57-to-E-258 non-penicillin-binding module which functions as a noncleaved, pseudointramolecular chaperone. Key elements of the folding information reside within the motif 1-containing R-60-to-W-110 polypeptide segment and within G-188-to-D-197 motif 3 of the n-PB module. The intermodule interaction is discussed in the light of the known three-dimensional structure (at 3.5-A [0.35-nm] resolution) of the analogous class B PBP2x of Streptococcus pneumoniae (S. Pares, N. Mouz, Y. Pétillot, R. Hakenbeck, and O. Dideberg, Nature Struct. Biol. 3:284-289, 1996). Correct folding and adoption of a stable penicillin-binding conformation are necessary but not sufficient to confer cell septation activity to PBP3 in exponentially growing cells. The in vivo activity of PBP3 also depends on the M-1-to-E-56 amino-terminal module which encompasses the cytosol, the membrane, and the periplasm and which functions as a noncleaved pseudo-signal peptide