Preoperative anemia is a risk factor for poor perioperative outcomes in ventral hernia repair.

PURPOSE: Ventral hernia repairs (VHR) are among the most commonly performed operations by general surgeons. Despite advances in technology there remains high complication and readmission rates. Preoperative anemia has been linked to poor outcomes and readmission across several surgical procedures, however the link to ventral hernia repair outcomes is limited. METHODS: Utilizing the American College of Surgeons National Safety and Quality Improvement Project (NSQIP) database for years 2016-2018, a total of 115,000 patients met inclusion criteria. Using propensity matching we matched two groups of patients who underwent VHR: (1) those with preoperative anemia and (2) those with normal hemoglobin levels. Anemia criteria was set forth by the World Health Organization (WHO). RESULTS: Univariate analysis did demonstrate statistical significance in post-operative outcomes percentage of serious surgical site infection, poor renal outcomes, transfusion, and unplanned remission in those with preoperative anemia who underwent VHR. In a multivariate analysis, patients who underwent ventral hernia repair with pre-operative anemia had significantly greater odds of unplanned readmission (odds ratio 1.35, 95% confidence interval 1.16-1.57) and serious surgical site infection (odds ratio 1.35, 95% confidence interval 1.04-1.74) independent of known risk factors such as smoking, diabetes and obesity. CONCLUSIONS: Preoperative anemia is a risk factor for poor postoperative outcomes in those undergoing ventral hernia repair and should be considered when evaluating a patient for repair.

Insights into alpha-K toxin specificity for K+ channels revealed through mutations in noxiustoxin.

Noxiustoxin (NxTX) displays an extraordinary ability to discriminate between large conductance, calcium-activated potassium (maxi-K) channels and voltage-gated potassium (Kv1.3) channels. To identify features that contribute to this specificity, we constructed several NxTX mutants and examined their effects on whole cell current through Kv1.3 channels and on current through single maxi-K channels. Recombinant NxTX and the site-specific mutants (P10S, S14W, A25R, A25Delta) all inhibited Kv1.3 channels with Kd values of 6, 30, 0.6, 112, and 166 nM, respectively. In contrast, these same NxTX mutants had no effect on maxi-K channel activity with estimated Kd values exceeding 1 mM. To examine the role of the alpha-carbon backbone in binding specificity, we constructed four NxTX chimeras, which altered the backbone length and the alpha/beta turn. For each of these chimeras, six amino acids comprising the alpha/beta turn in iberiotoxin (IbTX) replaced the corresponding seven amino acids in NxTX (NxTX-YGSSAGA21-27-FGVDRG21-26). The chimeras differed in length of N- and C-terminal residues and in critical contact residues. In contrast to NxTX and its site-directed mutants, all of these chimeras inhibited single maxi-K channels. Under low ionic strength conditions, Kd values ranged from 0.4 to 6 microM, association rate constant values from 3 x 10(7) to 3 x 10(8) M(-1) x s(-1), and time constants for block from 5 to 20 ms. The rapid blocked times suggest that key microscopic interactions at the toxin-maxi-K channel interface may be absent. Under physiologic external ionic strength conditions, these chimera inhibited Kv1.3 channels with Kd values from 30 to 10 000 nM. These results suggest that the extraordinary specificity of NxTX for Kv1.3 over maxi-K channels is controlled, in part, by the toxin alpha-carbon backbone. These differences in the alpha-carbon backbone are likely to reflect fundamental structural differences in the external vestibules of these two channels.

Properties of Ca(2+) release-activated Ca(2+) channel block by 5-nitro-2-(3-phenylpropylamino)-benzoic acid in Jurkat cells.

Ca(2+) release-activated Ca(2+) current (I(crac)) has been previously characterized biophysically in Jurkat lymphocytes and other non-excitable cells, but pharmacology remains poorly developed. The present objective was to delineate with whole cell recording details of the interaction of the chloride channel blocker, 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), with I(crac) in Jurkat cells. NPPB reversibly inhibited I(crac) in a concentration-dependent manner (IC(50)=5 microM). Kinetics for block and unblock of I(crac) by NPPB indicated a bimolecular interaction. Michaelis-Menten analysis indicated that NPPB interacts competitively with extracellular Ca(2+) permeating the I(crac) pathway. Finally, analysis of the pH dependence of I(crac) block by NPPB revealed a reduction in the apparent affinity during extracellular alkalinization that based on the pK(a) for NPPB, suggested that the neutral form of NPPB blocks the Ca(2+) release-activated Ca(2+) (CRAC) channel. Taken together, our results suggest a direct interaction between NPPB and the CRAC channel, and should help guide insights for developing novel and more selective analogues.

Extracellular site for econazole-mediated block of Ca2+ release-activated Ca2+ current (Icrac) in T lymphocytes.

1. Standard whole cell patch clamp recording techniques were used to study the pharmacological characteristics and site of econazole-mediated inhibition of calcium release-activated calcium current (Icrac) in the human leukaemic T cell line, Jurkat. 2. Extracellularly applied econazole blocked Icrac in a concentration-dependent manner (IC50 approximately 14 microM). Block developed over a relatively slow timecourse of 30-60 s (10 microM), and only partially reversed over minutes. 3. Econazole dialysed from the pipette into the cytosol at concentrations ranging from 0.1 to 30 microM did not reduce Icrac, or quantitatively affect Icrac block by extracellularly applied econazole. 4. A less lipophilic quaternary iodide derivative of econazole was synthesized to retard absorption through the cell membrane. When applied extracellularly, this compound blocked Icrac in a concentration-dependent manner with onset kinetics comparable to econazole. 5. Results with intracellularly dialysed econazole and the quaternary econazole derivative provide convergent evidence that econazole blocks Icrac via an extracellular interaction. 6. The inability of intracellularly applied econazole to inhibit Icrac argues against the notion that econazole inhibits capacitative Ca2+ entry pathways secondary to its known inhibitory effects on cytochrome P-450.

Calcium-dependent enhancement of depletion-activated calcium current in Jurkat T lymphocytes.

We have obtained evidence that the Ca(2+)-selective current activated by Ca2+ store depletion (Ca2+ release-activated Ca2+ current; Icrac) in Jurkat T lymphocytes is augmented in a time-dependent manner by Ca2+ itself. Whole cell patch clamp experiments employed high cytosolic Ca(2+)-buffering conditions to passively deplete Ca2+ stores. Rapidly switching to nominally Ca(2+)-free extracellular buffer instantaneously reduced Icrac measured at -100 mV to leak current level. Unexpectedly, readmission of 2 mM Ca2+ instantaneously restored only 38 +/- 5% (mean +/- SEM, n = 9) of the full Icrac amplitude. The remainder reappeared in a monotonic time-dependent manner over 10 to 20 sec. Rapid vs. slow intracellular Ca2+ chelators did not alter this process, and inorganic Icrac blockers did not regenerate it, arguing against an intracellular site of action. The effect was specific to Ca2+: introduction of the permeant ions, Ba2+ or Sr2+, failed to invoke time-dependent Icrac reappearance. Moreover, equimolar substitution of Ba2+ for Ca2+ initially produced Ba2+ current of similar magnitude to the full Ca2+ current, but the Ba2+ current decayed monotonically to < 50% of its initial amplitude in < 20 sec. Conversely, return to Ca2+ produced a time-dependent increase in Icrac to its larger Ca2+ permeation level. Thus Ca2+ appears to selectively promote a reversible transition of Icrac that results in larger current flux, and at least partially explains the selectivity of this current for Ca2+ over other divalent ions.

Residual Ca2+ channel current modulation by megestrol acetate via a G-protein alpha s-subunit in rat hypothalamic neurones.

1. The inhibition of voltage-activated Ca2+ channel currents by the orally active progesterone derivative, megestrol acetate (MA), was examined in freshly dissociated rat ventromedial hypothalamic nucleus (VMN) neurones using the whole-cell voltage-clamp technique with 10 mM Ba2+ as the charge carrier. 2. The steady-state inhibition of the peak high-threshold Ca2+ channel current evoked by depolarization from -80 to -10 mV by MA increased in a concentration-dependent fashion. MA inhibited a fraction of the whole-cell Ca2+ channel current while progesterone had no effect on the peak Ca2+ channel current (7% at 10 microM). The low-threshold Ca2+ (T-type) current, evoked from -100 to -30 mV, was unaffected by MA. 3. Intracellular dialysis with MA had no effect on the Ca2+ channel current. Concomitant extracellular perfusion of MA showed normal inhibitory activity, suggesting that the MA binding site can only be accessed extracellularly. 4. The high-threshold Ca2+ channel current in VMN neurones was found to consist of four pharmacologically distinguishable components: an N-type current, an L-type current, a P-type current, and a residual current. MA had no effect on the N-, L- and P-type Ca2+ channel currents, but inhibited the residual current. 5. In neurones isolated from cholera toxin-treated animals, the MA-induced inhibition of the Ca2+ channel current was significantly diminished, suggesting a G-protein alpha S-subunit involvement. 6. Treatment with antisense phosphothio-oligodeoxynucleotides to the G alpha S-subunit (antisense-G alpha S) significantly reduced the MA-induced inhibition of the Ca2+ channel current. Treatment with either sense-G alpha S or antisense-G alpha 11 had no effect, confirming a G alpha S-subunit involvement. 7. These results suggest that appetite enhancement induced by MA in cachectic patients may in part be due to a novel central nervous system action, that is, inhibition of a fraction of the whole-cell Ca2+ channel current to attenuate the firing of VMN neurones that may be involved in satiety mechanisms.

Withdrawal from the endogenous steroid progesterone results in GABAA currents insensitive to benzodiazepine modulation in rat CA1 hippocampus.

1. The withdrawal properties of the endogenous steroid progesterone (P) were tested in female rats as a function of benzodiazepine modulation of gamma-aminobutyric acid-A (GABAA)-gated current with the use of the whole cell patch-clamp technique on acutely dissociated CA1 hippocampal neurons. In a previous study, this steroid was shown to exhibit withdrawal properties, behaviorally. 2. One day withdrawal from in vivo administration of physiological doses of P (5 mg ip, 5 days/wk for 3 withdrawal cycles) or its metabolite, the GABAA modulator 3 alpha-hydroxy-5 alpha-pregnan-20-one (3 alpha,5 alpha-THP or allopregnanolone, 20 mg/kg ip) prevented the normally potentiating effect of lorazepam (LZM; 10(-7)-10(-4) M) on GABAA-gated current. Withdrawal from 500 micrograms P administered concomitantly with 2 micrograms 17 beta-estradiol also markedly diminished LZM potentiation of GABAA current. This effect was seen only after three withdrawal cycles. 3. P withdrawal produced no inhibitory effect on either basal levels of GABAA-evoked current, the GABAA EC50, or barbiturate (+/-Pentobarbital, 10(-7)-10(-4) M) modulation of this parameter. 4. The effect of steroid withdrawal on LZM modulation of GABAA-evoked current was blocked by picrotoxin as well as by indomethacin, a drug that prevents conversion of P to its metabolite, the GABAA modulator 3 alpha,5 alpha-THP. These results suggest that the withdrawal properties of P may be due to changes in GABAA receptor function produced by 3 alpha,5 alpha-THP.

Calcium current characterization in dissociated adult guinea-pig jugular ganglion neurons.

Voltage-dependent calcium (Ca2+) channel currents in freshly dissociated adult guinea-pig jugular ganglion neurons were examined and characterized using the whole-cell patch-clamp technique. Electrophysiological analysis demonstrated a high-threshold current, but no low-threshold or T-type current. A fraction of the total Ca2+ current was inhibited by omega (omega)-conotoxin GVIA (Cg (inTX; 10 microM); the dihydropyridine antagonist nifedipine (NIF; 10 microM), inhibited a large fraction of the CgTX-insensitive current. The remaining CgTX/NIF-insensitive current was completely inhibited by omega-agatoxin IVA (AgIVA; 100 nM). These results demonstrated that the whole-cell Ca2+ channel current consisted only of N-, L- P-type components. Of these currents, only the L-type was partially inhibited by both histamine and carbachol (0.01-100 microM).

Neurosteroids modulate calcium currents in hippocampal CA1 neurons via a pertussis toxin-sensitive G-protein-coupled mechanism.

The inhibition of Ca2+ channel currents by endogenous brain steroids was examined in freshly dissociated pyramidal neurons from the adult guinea pig hippocampal CA1 region. The steady-state inhibition of the peak Ca2+ channel current evoked by depolarizing steps from -80 to -10 mV occurred in a concentration-dependent manner with the following IC50 values: pregnenolone sulfate (PES), 11 nM; pregnenolone (PE), 130 nM; and allotetrahydrocorticosterone (THCC), 298 nM. THCC, PE, and PES depressed a fraction of the Ca2+ channel current with a maximal inhibition of 60% of the total current. However, substitution of an acetate group for the sulfate group on PES resulted in a complete loss of activity. Progesterone had no effect (4% inhibition at 100 microM). Intracellular dialysis of PES had no effect on the Ca2+ current; concomitant extracellular perfusion of PES showed normal inhibitory activity, suggesting that the steroid binding site can only be accessed extracellularly. Analysis of tail currents at -80 mV demonstrated that THCC and PES slowed the rate of Ca2+ current activation and deactivation with no change in the voltage dependence of activation. Inhibition of the Ca2+ channel current by THCC and PES was voltage dependent. THCC primarily inhibits the omega-conotoxin (CgTX)-sensitive or N-type Ca2+ channel current. PE was nonselective in inhibiting both the CgTX- and the nifedipine (NIF)-sensitive Ca2+ channel current. These neurosteroids had no effect on the CgTX/NIF-insensitive current. In neurons isolated from pertussis toxin (PTX)-treated animals by chronic intracerebroventricular infusion (1000 ng/24 hr for 48 hr), the Ca2+ channel current inhibition by PES, PE, and THCC was significantly diminished. Intracellular dialysis with GDP-beta-S (500 microM) also significantly diminished the neurosteroid inhibition of the Ca2+ channel current. Intracellular dialysis with the general kinase inhibitors H-7 (100 microM), staurosporine (400 nM), and a 20 amino acid protein kinase inhibitor (1 microM) also significantly prevented the THCC and PES inhibition of the Ca2+ channel current. Intracellular dialysis with the more specific inhibitors of protein kinase C (PKC), the pseudosubstrate inhibitor (PKCI 19-36) (1-2 microM) and bisindolylmaleimide (1 microM) significantly diminished the THCC and PE inhibition of the Ca2+ channel current. Rp- cAMP (100 microM), a specific inhibitor of cAMP-dependent protein kinase (PKA), had no effect on the THCC and PE inhibition of the Ca2+ current.(ABSTRACT TRUNCATED AT 400 WORDS)

Neurosteroids block Ca2+ channel current in freshly isolated hippocampal CA1 neurons.

Certain synthetic and endogenous steroids are known to modulate neuronal responses to gamma-aminobutyric acid (GABA) and also change the firing frequency of certain neurons. However, there is nothing known of the effect(s) of steroids on voltage-gated calcium currents in mammalian neurons. We show here that the steroids (0.1-100 microM) allotetrahydrocorticosterone (THCC), dehydroepiandrosterone sulfate (DHEAS) and pregnanolone can rapidly and reversibly depress voltage-gated calcium currents in freshly isolated adult hippocampal CA1 pyramidal neurons. This blocking action occurs in the presence of picrotoxin (10 microM). Tail current analysis shows that THCC appears to be a ligand that selectively and reversibly depresses the omega-conotoxin (fraction GVIA) sensitive portion of the calcium current. These results demonstrate that certain steroid metabolites have a direct membrane site of action which may influence brain excitability.

The neurosteroids pregnenolone and pregnenolone-sulfate but not progesterone, block Ca2+ currents in acutely isolated hippocampal CA1 neurons.

The neurosteroids pregnenolone (PE) and pregnenolone-sulfate (PS) have been shown to interact with the GABAA receptor in the central nervous system. In contrast, nothing is known of any possible modulation of voltage-gated calcium channels (VGCC). We have examined the interaction of PE, PS and progesterone on VGCC in acutely isolated adult guinea-pig hippocampal CA1 neurons using the whole-cell patch clamp technique. PE and PS depressed the calcium current at low micromolar concentrations (0.001-100 microM). The time to peak of the calcium current was slowed by PE and PS. The blocking action of PE and PS occurs in the presence of 10 microM picrotoxin. In contrast, progesterone had no effect on the Ca2+ current, indicating specificity for PE and PS. These results demonstrate a direct and novel membrane site of action for PE and PS, suggesting a possible role influencing brain excitability.