Guidelines for laparoscopic treatment of ventral and incisional abdominal wall hernias (International Endohernia Society (IEHS)-part 1.

Guidelines are increasingly determining the decision process in day-to-day clinical work. Guidelines describe the current best possible standard in diagnostics and therapy. They should be developed by an international panel of experts, whereby alongside individual experience, above all, the results of comparative studies are decisive. According to the results of high-ranking scientific studies published in peer-reviewed journals, statements and recommendations are formulated, and these are graded strictly according to the criteria of evidence-based medicine. Guidelines can therefore be valuable in helping particularly the young surgeon in his or her day-to-day work to find the best decision for the patient when confronted with a wide and confusing range of options. However, even experienced surgeons benefit because by virtue of a heavy workload and commitment, they often find it difficult to keep up with the ever-increasing published literature. All guidelines require regular updating, usually every 3 years, in line with progress in the field. The current Guidelines focus on technique and perioperative management of laparoscopic ventral hernia repair and constitute the first comprehensive guidelines on this topic. In this issue of Surgical Endoscopy, the first part of the Guidelines is published including sections on basics, indication for surgery, perioperative management, and key points of technique. The next part (Part 2) of the Guidelines will address complications and comparisons between open and laparoscopic techniques. Part 3 will cover mesh technology, hernia prophylaxis, technique-related issues, new technologic developments, lumbar and other unusual hernias, and training/education.

Synthesis and anti-melanoma activity of analogues of N-acetyl-4-S-cysteaminylphenol substituted with two methyl groups alpha to the nitrogen.

N-Acetyl-4-S-cysteaminylphenol 1 is an analogue of a biosynthetic intermediate in the pathway to melanin. It is probably oxidized to an o-quinone which can alkylate cellular nucleophiles resulting in interference with cell growth and proliferation. It is reported to have useful anti-melanoma activity. We previously synthesized a range of analogues of 1 by varying the acyl portion of the amide. A modest increase in melanoma activity against six melanoma cell lines for these analogues could be correlated with increased lipophilicity. Thirteen new analogues of 1 containing two methyl groups at the alpha-position of the amino component and various acyl groups have now been prepared and assessed for anti-melanoma activity against six human melanoma cell lines. Most of the new compounds displayed greater cytotoxicity than the lead compound 1. The highest cytotoxicity against the cell lines was observed for the cyclohexylacetamide 11 followed by the cyclohexylcarboxamide 10 and the 2,2-dimethylpropanamide 6. The IC50 values of the most cytotoxic compound 11 against the cell lines were comparable with those of cisplatin. Small variations in the acyl components of these analogues, such as reducing the ring size, lengthening the carbon chain and reducing the amount of chain branching, resulted in a considerable loss of cytotoxicity. The moderate activity of 6, 10 and 11 against SK-Mel-24 cells (non-tyrosinase containing) and an ovarian cell line suggests that interference with the melanin pathway may not be their only mode of action.

Knowledge-based design of bimodular and trimodular polyketide synthases based on domain and module swaps: a route to simple statin analogues.

BACKGROUND: Polyketides are structurally diverse natural products that have a range of medically useful activities. Nonaromatic bacterial polyketides are synthesised on modular polyketide synthase (PKS) multienzymes, in which each cycle of chain extension requires a different 'module' of enzymatic activities. Attempts to design and construct modular PKSs that synthesise specified novel polyketides provide a particularly stringent test of our understanding of PKS structure and function. RESULTS: We have constructed bimodular and trimodular PKSs based on DEBS1-TE, a derivative of the erythromycin PKS that contains only modules 1 and 2 and a thioesterase (TE), by substituting multiple domains with appropriate counterparts derived from the rapamycin PKS. Hybrid PKSs were obtained that synthesised the predicted target triketide lactones, which are simple analogues of cholesterol-lowering statins. In constructing intermodular fusions, whether between modules in the same or in different proteins, it was found advantageous to preserve intact the acyl carrier protein-ketosynthase (ACP-KS) didomain that spans the junction between successive modules. CONCLUSIONS: Relatively simple considerations govern the construction of functional hybrid PKSs. Fusion sites should be chosen either in the surface-accessible linker regions between enzymatic domains, as previously revealed, or just inside the conserved margins of domains. The interaction of an ACP domain with the adjacent KS domain, whether on the same polyketide or not, is of particular importance, both through conservation of appropriate protein-protein interactions, and through optimising molecular recognition of the altered polyketide chain in the key transfer of the acyl chain from the ACP of one module to the KS of the downstream module.

Evaluating precursor-directed biosynthesis towards novel erythromycins through in vitro studies on a bimodular polyketide synthase.

BACKGROUND: Modular polyketide synthases (PKSs) catalyse the biosynthesis of complex polyketides using a different set of enzymes for each successive cycle of chain extension. Directed biosynthesis starting from synthetic diketides is a potentially valuable route to novel polyketides. We have used a purified bimodular derivative of the erythromycin-producing polyketide synthase (DEBS 1-TE) to study chain extension starting from a variety of diketide analogues and, in some cases, from the alternative acyl-CoA thioester substrates. RESULTS: Chain initiation in vitro by DEBS 1-TE module 2 using a synthetic diketide analogue as a substrate was tolerant of significant structural variation in the starter unit of the synthetic diketide, but other changes completely abolished activity. Interestingly, a racemic beta-keto diketide was found to be reduced in situ on the PKS and utilised in place of its more complex hydroxy analogue as a substrate for chain extension. The presence of a diketide analogue strongly inhibited chain initiation via the loading module. Significantly higher concentrations of diketide N-acetylcysteamine analogues than their corresponding acyl-CoA thioesters are required to achieve comparable yields of triketide lactones. CONCLUSIONS: Although a broad range of variation in the starter residue is acceptable, the substrate specificity of module 2 of a typical modular PKS in vitro is relatively intolerant of changes at C-2 and C-3. This will restrict the usefulness of approaches to synthesise novel erythromycins using synthetic diketides in vivo. The use of synthetic beta-keto diketides in vivo deserves to be explored.

The molecular basis of Celmer's rules: the stereochemistry of the condensation step in chain extension on the erythromycin polyketide synthase.

Modular polyketide synthases (PKSs), for example, the 6-deoxyerythronolide B synthase (DEBS) responsible for synthesis of the aglycone core of the macrolide antibiotic erythromycin, generate an impressive diversity of asymmetric centers in their polyketide products. However, as noted by Celmer, macrolides have the same absolute configuration at all comparable stereocenters. Understanding how the stereochemistry of chain extension in controlled is therefore crucial to determining the common mechanism of action of these enzymes. We aimed to elucidate the molecular basis of Celmer's rules through in vitro studies with DEBS 1-TE, a bimodular derivative of DEBS from Saccharopolyspora erythraea, which uses (2S)-methylmalonyl-coenzyme. A to produce both D- and L-methyl centers in its triketide lactone product. We show here that condensation of (2S)-methylmalonyl-CoA in module 2 proceeds with decarboxylative inversion without cleavage of the C-H bond adjacent to the methyl group; in contrast, in module 1 the chain extension process involves loss of the hydrogen attached to C-2 of the methylmalonyl-CoA precursor. The production of the D-methyl center in module 2 without loss of hydrogen from the asymmetric center of the (2S)-methylmalonyl-CoA establishes that condensation takes place with inversion of configuration as in fatty acid biosynthesis. The loss of the key hydrogen from the (2S)-methylmalonyl-CoA to produce the L-methyl center generated in module 1 implies that an additional obligatory epimerization step takes place in that module. The nature and timing of the epimerization remain to be established.

Low-frequency vibration emitted from unstable hip in human neonate.

Developmental dysplasia of the hip (DDH) continues to be an orthopedic enigma. Some authors still believe it is a purely birth phenomenon. Even with widespread birth screening, however, DDH continues to become evident later than three months of age, long after a satisfactory outcome can be guaranteed. In an effort to reduce the number of late manifestations, the authors have developed a noninvasive form of screening for DDH called vibration arthrometry. Five hundred neonates were examined in local maternity hospitals, according to the guidelines of Ortolani and Barlow. The new method involves the attachment of miniature accelerometers around the infant's pelvis. Using this method, it was possible to elicit vibration events from approximately one fourth (255 hips) of the hips tested; vibrations were recorded from normal hips (125), from "clicky" hips (128), and from unstable hips (two). Differences between "nil-felt" (clinically silent) and "click-felt" (palpable clicking on testing) were significant. Vibration testing can be seen as an aid in the manual palpation necessary to detect this crippling condition.