Biomechanics applied to incisional hernia repair - Considering the critical and the gained resistance towards impacts related to pressure.

BACKGROUND: Incisional hernia repair is burdened with recurrence, pain and disability. The repair is usually carried out with a textile mesh fixed between the layers of the abdominal wall. METHODS: We developed a bench test with low cyclic loading. The test uses dynamic intermittent strain resembling coughs. We applied preoperative computed tomography of the abdomen at rest and during Valsalva's maneuver to the individual patient to analyze tissue elasticity. FINDINGS: The mesh, its placements and overlap, the type and distribution of fixation elements, the elasticity of the tissue of the individual and the closure of the abdominal defect-all aspects influence the reconstruction necessary. Each influence can be attributed to a relative numerical quantity which can be summed up into a characterizing value. The elasticity of the tissues within the abdominal wall of the individual patient can be assessed with low-dose computed tomography of the abdomen with Valsalva's maneuver. We established a procedure to integrate the results into a surgical concept. We demonstrate potential computer algorithms using non-rigid b-spline registration and artificial intelligence to further improve the evaluation process. INTERPRETATION: The bench test yields relative values for the characterization of hernia, mesh and fixation. It can be applied to patient care using established procedures. The clinical application in the first ninety-six patients shows no recurrences and reduced pain levels after one year. The concept has been spread to other surgical groups with the same results in another fifty patients. Future efforts will make the abdominal wall reconstruction more predictable.

Pharmacological characterisation of 5-hydroxytryptamine-induced contractile effects in the isolated gut of the lepidopteran caterpillar Spodoptera frugiperda.

The indolealkylamine 5-hydroxytryptamine (5-HT, 0.1nM-1&mgr;M) caused dose-dependent increases in the number of contractions observed in guts isolated from the caterpillar Spodoptera frugiperda. Of the 5-HT analogues tested for agonist action, 2-methyl-5-HT (0.1-10&mgr;M) was a full agonist with reduced potency while alpha-methyl-5-HT (0.1-100&mgr;M), 5-carboxamidotryptamine (0.1-100&mgr;M), 5-methoxytryptamine (5-MeOT) (10nM-10&mgr;M), and tryptamine (1-100&mgr;M) were partial agonists. Incubation of isolated guts with proven mammalian 5-HT receptor antagonists showed that cyproheptadine (10nM-1&mgr;M), MDL 72222 (1-10&mgr;M), tropisetron (1-10&mgr;M) and 5-benzoyloxygramine (1-10&mgr;M) were potent non-competitive antagonists of 5-HT-induced tissue contraction. In comparison, ketanserin (0.1-1&mgr;M) was a competitive antagonist. The mammalian selective serotonin reuptake inhibitors, clomipramine (10nM-10&mgr;M) and fluoxetine (10nM-10&mgr;M) also caused non-competitive inhibition of 5-HT-induced contraction while fluvoxamine (10nM-10&mgr;M) was a weak competitive antagonist. Low doses of clomipramine (0.1&mgr;M) caused potentiation of 5-HT-induced gut contraction thereby suggesting the presence of 5-HT reuptake systems in this tissue. The contractile effects of 5-HT were inhibited by verapamil, Li(+) and H7 and potentiated by theophylline thereby indicating that L-type Ca(2+) channels, phosphatidylinositol second messengers and cAMP, respectively, are involved in 5-HT-induced tissue contraction. The 5-HT receptors mediating contractility in the gut of S. frugiperda have properties in common with mammalian 5-HT(2) and Drosophila 5-HT(dro2A/2B) receptors. In addition, these data suggest that the tissue also contains receptors that are similar to mammalian 5-ht(6) and 5-HT(7) as well as Drosophila(dro1) receptors. However, the primary amino acid sequence of these lepidopteran 5-HT receptors will have to be elucidated before full comparisons can be made.

Structure-activity relationship of contractile effects induced by helicokinins in the isolated gut of the lepidopteran caterpillar Spodoptera frugiperda.

The diuretic helicokinins YFSPWG-amide (Hez KI), VRFSPWG-amide (Hez KII) and KVKFSAWG-amide (Hez KIII) are potent contractants of the isolated gut of the caterpillar Spodoptera frugiperda at doses ranging from 0.1 to 10nM. In comparison, the pentapeptide FSPWG-amide was a full agonist with greatly reduced potency while SPWG-amide and PWG-amide were weak partial agonists. Substitution of individual amino acids in Hez KI with alanine revealed that replacement of the [phenylalanine(2)] residue caused a large fall in potency while replacement of [tryptophan(5)] residue caused complete loss of myogenic activity. The striking fall in potency of YASPWG-amide and the lack of activity of YFSPAG-amide confirm the requirement for aromatic groups in positions 2 and 3 of the core pentapeptide as well as supporting the ideas that the active core of these peptides adopts a beta-turn when interacting with receptors, bringing together the [Phe] and [Trp] residues that are critical for activity. Neither the pentapeptide proctolin nor the potent mammalian gut contractant Substance P were able to cause contraction when applied to caterpillar gut tissue. Incubation of isolated gut tissue in the phosphodiesterase inhibitor theophylline (10-100&mgr;M) caused significant potentiation of the response to applied Hez KI. Conversely, in the presence of the L-type Ca(2+) channel blocker verapamil (10&mgr;M-1mM) or Co(2+) (1-50mM) the contractile effects of Hez KI were attentuated significantly. These data suggest that the gut of S. frugiperda contains G-protein-linked kinin receptors that utilise cyclic AMP as their second messenger system and cause contraction by promoting the entry of extracellular Ca(2+).

Syntheses of analogues of the insect neuropeptide proctolin containing an oxazole ring as an amide bond replacement.

[structure: see text]. Three oxazole analogues of the insect neuropeptide proctolin (H-Arg-Tyr-Leu-Pro-Thr-OH) have been prepared, containing a single oxazole between Tyr and Pro and between Pro and Thr, respectively. A compound containing an oxazole moiety between Tyr and Pro and between Pro and Thr has also been prepared. All compounds have been tested for myotropic activity.

Effect of helicokinins and ACE inhibitors on water balance and development of Heliothis virescens larvae.

The diuretic activity of the helicokinins I (YFSPWG-amide), II (VRFSPWG-amide) and III (KVKFSAWG-amide) was tested on Heliothis virescens larvae. All three kinins increased fluid secretion in isolated Malpighian tubules in a dose-dependent manner. Injections into the haemolymph caused a significant reduction in weight gain after 24 h and, in the case of helicokinin I, led to an increased mortality of 43% within 6 days. When truncated analogues of helicokinin I were tested in vitro, only the pentapeptide (FSPWG-amide) stimulated fluid secretion. Tested in vivo the pentapeptide did not influence normal development of the larvae. An alanine scan of helicokinin I showed that the substitution of phenylalanine, tryptophan and glycine led to a massive decrease or even loss of diuretic activity. The substitution of the other amino acids had no effect in vitro. The ACE inhibitors captopril, enalapril-maleate and lisinopril were tested for their influence on the development of the larvae. In combination with one of the helicokinins the in vivo injection of the ACE inhibitors led to increased rates of mortality and/or reductions in pupal weight.

Interaction between Manduca sexta allatotropin and manduca sexta allatostatin in the fall armyworm Spodoptera frugiperda.

A peptide that strongly stimulates juvenile hormone (JH) biosynthesis in vitro by the corpora allata (CA) was purified from methanolic brain extracts of adult Spodoptera frugiperda. Using HPLC separation followed by Edman degradation and mass spectrometry, the peptide was identified as Manduca sexta allatotropin (Mas-AT). Treating the CA from adult S. frugiperda with synthetic Mas-AT (at 10(-6) M) caused an up to sevenfold increase in JH biosynthesis. The stimulation of JH synthesis was dose-dependent and reversible. Synthetic M. sexta allatostatin (Mas-AS) (10(-6) M) did not affect the spontaneous rate of JH secretion from CA of adult S. frugiperda, nor did any of the allatostatins of the Phe-Gly-Leu-amide peptide family tested. However, when CA had been activated by Mas-AT (10(-6) M), addition of synthetic Mas-AS (10(-6) M) reduced JH synthesis by about 70%. This allatostatic effect of Mas-AS on allatotropin-activated glands was also reversible. When CA were incubated in the presence of both Mas-AT (10(-6) M) and various concentrations of Mas-AS (from 10(-8) to 10(-5) M), the stimulation of JH-biosynthesis observed was inhibited in a dose-dependent manner. The experiments demonstrate a novel mechanism of allatostatin action. In S. frugiperda JH synthesis was inhibited only in those glands which had previously been activated by an allatotropin.

Detection of major and minor sex pheromone components by the male codling moth Cydia pomonella (Lepidoptera: Tortricidae).

Electroantennograms (EAGs) recorded from the antennae of male Cydia pomonella L. in response to stimulation with doses of the main sex pheromone component E8,E10-dodecadienol (Codlemone) ranging from 5ng to 500&mgr;g did not differ in their amplitudes from responses obtained to a synthetic 7-component pheromone blend containing the same absolute quantities of Codlemone. Based on differences in spike amplitudes obtained in Single Cell recordings (SCR), Sensilla trichodea on the antenna of males were found to contain at least three receptor neurone types. Two olfactory receptor neurones were tuned to Codlemone, while the third failed to be stimulated by Codlemone or by the minor components of the pheromone blend. As spike activity of the neurones in the S. trichodea stimulated by the 7-component blend did not differ from that of stimulation by Codlemone alone it appears that none of the receptor neurones is sensitive to any of the minor components tested. Scanning-electron-microscopical (SEM) examination of Sensilla auricillica on the antennae of Cydia males revealed two morphologically distinct types: rabbit eared shoehorn and regular shoehorn. SCR from these sensilla showed that only olfactory receptor neurones located in the rabbit-eared shoehorn type were tuned to the minor components. Differences in spike amplitudes (large, intermediate, small) allowed three types of neurones to be distinguished. Only the spike frequency of the intermediate receptor neurone was increased by application of the minor components E8-dodecenol, E9-dodecenol, dodecanol, tetradecanol, hexadecanol and E8,E10-dodecadienal. None were stimulated by Codlemone. These results are discussed in relation to the behavioural role of the minor pheromone components of C. pomonella.

Contrasting effects of sera from rabbits and cattle infested with ticks on the in vitro feeding performance of the tick Rhipicephalus appendiculatus.

The in vitro feeding activity of partially engorged Rhipicephalus appendiculatus (Neumann) (Acari: Ixodidae) females fed on sera from uninfested hosts was compared to that of ticks fed serum of hosts which had previously been infested with ticks. Although ticks fed best on sera from bovid hosts which had no prior exposure to this ectoparasite, two infestations of a bovid had no significant effect on the acceptability of its serum. In contrast, ticks fed sera from rabbits which had twice been infested with ticks gained significantly less weight than those fed serum obtained from the same animals before the infestations. Clearly there is a difference between natural host resistance and that of laboratory animals.