Long term outcomes of abdominal wall reconstruction using open component separation and biologic mesh in the liver, kidney, and small bowel transplant population.

PURPOSE: The aim of this study is to critically examine the multidisciplinary approach to abdominal wall reconstruction (AWR) in the solid organ transplant (SOT) population at our institution, MedStar Georgetown University Hospital, using a modified component separation technique (CST). METHODS: A retrospective review of AWR utilizing modified open CST with biologic mesh in SOT patients was performed from January 2010 to June 2018. Patient demographics, comorbidities, operative details, complications, and outcomes were recorded. Descriptive statistics, logistic and linear regression analyses were performed to appraise outcomes. RESULTS: Thirty-five patients were included; mean age was 53 years. Patient demographics and comorbidities were: 82.9% male, 45.7% history of tobacco use, and 28.6% diabetes. Fifty-one percent had undergone prior hernia repair. Transplant types were: kidney (9), liver (16), liver/kidney (1), small bowel (7), multivisceral (2). All were on an immunosuppressive regimen at time of surgery; 22.9% included steroids. Average defect size was 361 cm2. Additional soft tissue procedures were performed in 65.7% (n = 23) of patients. Median time to healing was 29.0 days. Complication rate was 31.4% (n = 11); six patients required reoperation within 90 days. Recurrence rate was 5.7% (n = 2) at mean of follow up of 3.0 years. Additional soft tissue procedures were statistically significant for healing time (p = 0.037). Steroid use was statistically significant for reoperation within 90 days (OR = 12.500; 95% CI 1.694-92.250); however, steroid use was not significant after correction for confounders. CONCLUSION: Modified open CST with biologic mesh is a safe, efficacious approach to complex AWR in the SOT population with recurrence rates comparable to the general population.

The 5-HT2 receptor antagonist, MDL 28,133A, disrupts the serotonergic-dopaminergic interaction mediating the neurochemical effects of 3,4-methylenedioxymethamphetamine.

The selective 5-HT2 receptor antagonist MDL 28,133A dose dependently-blocked the long-term deficits in rat brain 5-HT concentrations produced by the substituted amphetamine analogue 3,4-methylenedioxymethamphetamine (MDMA). This protective effect of MDL 28,133A could be abolished by coadministration of the dopamine precursor, L-dihydroxyphenylalanine (L-DOPA). Electrophysiological experiments demonstrated that the ability of MDL 28,133A to block the MDMA-induced slowing of A9 dopaminergic neurons was also sensitive to L-DOPA administration. Both sets of experiments suggest an interaction of MDL 28,133A at the level of dopamine synthesis. Consistent with this explanation, MDL 28,133A antagonized the MDMA-induced stimulation of dopamine synthesis in vivo. MDMA-induced 5-HT release did not reduce the firing rate of dopaminergic neurons as assessed by dopamine depletion following synthesis inhibition with alpha-methyl-p-tyrosine (alpha-MPT). This indicates that the effect of 5-HT2 receptor antagonists on MDMA-induced dopamine synthesis is not due simply to the removal of an inhibitory serotonergic input followed by an increase in dopamine cell firing and autoreceptor activation. MDL 28,133A was also shown to be without effect on the sensitivity of terminal dopamine autoreceptors. The results are consistent with the hypothesis that 5-HT2 receptors are permissive for the stimulation of dopamine synthesis necessary to support MDMA-induced transmitter efflux.

Effects of the serotonin releasers 3,4-methylenedioxymethamphetamine (MDMA), 4-chloroamphetamine (PCA) and fenfluramine on acoustic and tactile startle reflexes in rats.

The substituted amphetamines 4-chloroamphetamine (PCA), 3,4-methylenedioxymethamphetamine (MDMA) and fenfluramine (FEN) share the common neurochemical action of acutely releasing central serotonin (5-HT), and yet their behavioral effects are quite different. The present study evaluated the effects of these compounds on acoustic and tactile startle reflexes. PCA and MDMA were qualitatively similar in producing dose-related increases in acoustic and tactile startle reflexes that were slow in onset, but sustained throughout the 3.5-hr test session. Changes in motor activity did not account for the observed excitation of startle. In marked contrast to MDMA and PCA, FEN did not alter tactile startle and tended to depress acoustic startle. The excitatory effect of 20 mg/kg of MDMA was prevented by the 5-HT uptake blockers MDL 27,777A and fluoxetine. MDMA excitation was not affected by a dose of the dopamine antagonist haloperidol that attenuated the startle-enhancing effect of d-amphetamine. MDMA excitation was greatly attenuated by a general depletion of central 5-HT produced by prior intraventricular injection of the 5-HT neurotoxin 5,7-dihydroxytryptamine. PCA and MDMA excitations of startle were attenuated in rats specifically depleted of spinal 5-HT or in rats with radio frequency lesions of the dorsal raphe nucleus. Thus, PCA and MDMA have similar prolonged excitatory effects on startle reflexes that are mediated by ascending (dorsal raphe) and descending (spinal) pathways, whereas FEN differs in its lack of excitation of startle. Differences in the neurochemical properties of these compounds or their patterns of 5-HT release may underlie their different behavioral profiles.

L-DOPA potentiation of the serotonergic deficits due to a single administration of 3,4-methylenedioxymethamphetamine, p-chloroamphetamine or methamphetamine to rats.

The role of dopamine in the serotonergic neurotoxicity of 3,4-methylenedioxymethamphetamine, p-chloroamphetamine, methamphetamine, N-ethyl-3,4-methylenedioxyamphetamine and fenfluramine was assessed by determining the long-term effect of their coadministration with the dopamine precursor, L-DOPA (L-2,4-dihydroxyphenylalanine). L-DOPA administration potentiated the regional deficits in brain concentrations of serotonin measured one week after a single high dose of 3,4-methylenedioxymethamphetamine, p-chloroamphetamine or methamphetamine but did not alter the neurochemical response to N-ethyl-3,4-methylenedioxyamphetamine nor to fenfluramine. Consistent with this, in vitro release studies found the latter two agents to be the weakest of the five at increasing [3H]dopamine efflux from preloaded rat striatal slices. As an estimate of in vivo release, the effect of each agent on striatal dopamine concentrations was determined. Only those agents showing a synergism with L-DOPA in the long-term studies also produced changes in striatal dopamine consistent with an increase in transmitter release and synthesis. These results provide additional support for the hypothesis that dopamine release plays a role in the neurotoxicity of methylenedioxymethamphetamine, p-chloroamphetamine and methamphetamine. The lack of effect of L-DOPA on the neurotoxicity of fenfluramine as well as the modest effects of fenfluramine on dopamine release indicate this drug may produce its long-term effects on the serotonergic system through a unique mechanism not involving dopamine.

MDL 27,032 [4-propyl-5-(4-pyridinyl)-2(3H)-oxazolone], an active site-directed inhibitor of protein kinase C and cyclic AMP-dependent protein kinase that relaxes vascular smooth muscle.

MDL 27,032 [4-propyl-5-(4-pyridinyl)-2(3H)-oxazolone] is a novel vasodilator whose mechanism of action has not been elucidated. We investigated whether smooth muscle relaxation by MDL 27,032, in vitro, may involve an alteration in the activity of protein kinase C, cyclic AMP (cAMP)-dependent protein kinase or myosin light chain kinase by investigating the effects of MDL 27,032 on cyclic nucleotide phosphodiesterases (PDEs) and protein kinase activities. Strips of dog femoral artery or saphenous vein contracted with phorbol 12-myristate 13-acetate (PMA) were relaxed by 100 microM concentrations of MDL 27,032, as well as by other known inhibitors of PDEs [3-isobutyl-1-methylxanthine and papaverine], myosin light chain kinase (W-7) and protein kinase C (H-7 and polymyxin B). In contrast to 3-isobutyl-1-methylxanthine and papaverine, MDL 27,032 was either inactive or weak as an inhibitor of purified PDE types I, II, IVa and IVb. Similarly, it was a weak inhibitor of myosin light chain kinase. However, MDL 27,032 was a significantly more potent inhibitor of protein kinase C and cAMP-dependent protein kinase in cytosolic extracts of dog vein. Kinetic experiments utilizing purified rat brain protein kinase C revealed that inhibition with MDL 27,032 was competitive with Mg(++)-ATP (Ki 24 microM) and noncompetitive with phospholipid, diacylglycerol, PMA, calcium or substrate proteins. Inhibition of the catalytic subunit of cAMP-dependent protein kinase was also competitive with Mg(++)-ATP (Ki 14.3 microM). Similar results were obtained with MDL 27,032 and H-7 on both enzymes.(ABSTRACT TRUNCATED AT 250 WORDS)

Selective 5-hydroxytryptamine2 receptor antagonists protect against the neurotoxicity of methylenedioxymethamphetamine in rats.

The serotonergic deficits resulting from methylenedioxymethamphetamine (MDMA)-induced neurotoxicity were prevented by the simultaneous administration of 5-hydroxytryptamine2 (5-HT2) receptor antagonists such as MDL 11,939 or ritanserin. This effect was not region specific as protection was observed in the cortex, hippocampus and striatum 1 week after the administration of a single dose of MDMA. MDL 11,939 also showed some efficacy at reducing the deficits in 5-HT concentrations and tryptophan hydroxylase activity produced by multiple administrations of MDMA. Protection against the neurotoxicity required the administration of MDL 11,939 within 1 hr of MDMA indicating 5-HT2 receptor activation was an early event in the process leading to terminal damage. Examination of the effect of the 5-HT2 receptor blockade on the early neurochemical alterations induced by MDMA revealed an inhibitory effect on MDMA-stimulated dopamine synthesis. Analysis of these data and the associated changes in dopamine metabolites indicates that 5-HT2 receptor antagonists block MDMA-induced neurotoxicity by interfering with the ability of the dopamine neuron to maintain its cytoplasmic pool of transmitter and thereby sustain carrier-mediated dopamine release.

Chloral hydrate anesthesia antagonizes the neurotoxicity of 3,4-methylenedioxymethamphetamine.

We report that maintaining rats under chloral hydrate anesthesia for the first 3 h following the administration of 3,4-methylenedioxymethamphetamine (MDMA) blocks the decrease in forebrain concentrations of 5-hydroxytryptamine (5-HT) measured 1 week later. In contrast, the acute effect of MDMA (3 h) on forebrain 5-HT was not altered by the anesthetic. This protective effect of chloral hydrate was not due to an anesthetic-induced hypothermia but may be related to the hypothesized role of dopamine in the neurotoxic effects of MDMA.

Methylenedioxymethamphetamine-induced hyperthermia and neurotoxicity are independently mediated by 5-HT2 receptors.

Methylenedioxymethamphetamine (MDMA) produced a significant hyperthermia in rats which was antagonized in a competitive manner by the selective 5-HT2 antagonist, MDL 11,939. The 5-HT antagonist also blocked MDMA-induced neurotoxicity as assessed by the decline in regional 5-HT concentrations observed 1 week later. These two effects of MDL 11,939 were dissociated at higher doses of MDMA where the antagonist still provided virtually complete protection against the neurochemical deficits but only partially attenuated the hyperthermic response. In contrast to the effect of the 5-HT2 antagonist, haloperidol did not alter MDMA-induced hyperthermia but did antagonize its long-term neurochemical effects. Similarly, coadministration of the selective 5-HT uptake inhibitor, MDL 27,777, did not affect the hyperthermia produced by a high dose of MDMA but completely prevented the depletion of 5-HT. When the MDMA-induced hyperthermia was prevented by temporarily maintaining animals at reduced ambient temperature, the neurochemical changes normally observed 1 week later were also blocked. Although these results demonstrate that the drugs tested do not antagonize MDMA-induced neurotoxicity by interfering with its effect on body temperature, they do indicate that MDMA-induced hyperthermia may contribute to the development of the drug's long-term neurochemical effects.

Antagonism of the neurotoxicity due to a single administration of methylenedioxymethamphetamine.

The role of transmitter release in the serotonergic neurotoxicity of methylenedioxymethamphetamine (MDMA) was examined using treatments altering MDMA-induced release or its consequences. The long-term decrease in 5-HT concentrations and tryptophan hydroxylase activity produced by MDMA was antagonized by depletion of vesicular monoamines with reserpine or interruption of monoamine synthesis with the decarboxylase inhibitor, monofluoromethyl DOPA (dihydroxyphenylalanine). Similar results were achieved by selectively inhibiting dopamine synthesis with alpha-methyl-p-tyrosine or through bilateral lesions of the substantia nigra with 6-hydroxydopamine. The dopamine receptor antagonist haloperidol was also effective in this regard. Although these results strongly implicate dopamine release in the long-term neurochemical effects of MDMA, protection was also provided by selective 5-HT2 antagonists indicating that the neurotoxicity is dependent upon the release of both dopamine and 5-HT.