A retrospective study of pre-operative fasting times prior to elective or emergency cesarean birth in a large maternity hospital: Lessons to be learned to minimize the fasting time.

INTRODUCTION: When managing elective and emergency cesarean births in the same operating room, unpredictable variations in the start times of the cesareans can prolong fasting periods. METHODS: The fasting times were retrospectively analyzed on 279 consecutive cesarean births at Helsinki University Women's Hospital, Finland, during January-February 2023. The fasting times were compared between the urgency groups and for elective cesareans according to their scheduled order on the operation list. The primary outcome was the difference in the fasting times for food and drink, while the secondary outcome was fasting for both food >12 h and fluids >4 h. The fasting times were compared by one-way ANOVA and chi-squared test, respectively. Dichotomous data are presented as unadjusted odds ratios (OR with 95% CI). RESULTS: Increasing urgency was associated with shorter fasting times. Fasting times for elective cesareans increased with the scheduled order on the daily list. The mean fasting periods (SD) increased from 10.55 h (SD=1.57) to 14.75 h (SD=2.02) from the first to the third cesarean of the day (p<0.01). The unadjusted odds ratio (95% CI) for fasting of the scheduled cesareans to exceed 12 h for solid foods and 4 h for clear fluids was 6.53 (95% CI: 2.67-15.9, p<0.001), for the third and fourth cesareans compared to the first two cesareans of the day. CONCLUSIONS: When elective and emergency cesareans are performed by the same team, the woman undergoing the third elective surgery of the day should be advised to have breakfast before 5 a.m. at home. While waiting for the operation, a carbohydrate drink should be offered to limit the fast.

Intrathecal atipamezole augments the antinociceptive effect of morphine in rats.

BACKGROUND: Opioid analgesics are effective in the treatment of chronic pain, but they have serious adverse effects such as development of tolerance and dependence. Adrenergic α(2) agonists and µ-opioid receptor agonists show synergistic potentiation and cross-tolerance in spinal analgesia, whereas α(2)-adrenergic antagonists have shown pronociceptive effects. However, at ultralow doses, spinal α(2)-adrenergic antagonists have been reported to paradoxically enhance opioid antinociception. New data have suggested a functional µ-opioid-α(2)-adrenoceptor complex, which may help in interpreting the paradoxical effect of the α(2)-adrenergic antagonists. In the present study we assessed the effects of low doses of atipamezole, a nonselective α(2)-adrenergic antagonist, on both systemic and spinal morphine antinociception and tolerance. METHODS: Antinociception was assessed in male Sprague-Dawley rats using hotplate, tail-flick, and paw pressure tests. Spinal or systemic opioid tolerance was induced for 4 days. The effects of both intrathecal and subcutaneous atipamezole on acute morphine-induced antinociception and established morphine tolerance were studied. RESULTS: Systemic or spinal atipamezole itself did not produce antinociception at the doses studied (subcutaneous 0.03, 0.3, 3 µg/kg or intrathecal 0.1, 1, 10 ng). The combined administration of spinal morphine and 1 ng of atipamezole increased the antinociceptive effect of acute spinal morphine 30 minutes after the administration of test drugs in the tail-flick test. Furthermore, 10 ng of intrathecal atipamezole attenuated established morphine tolerance 30 minutes after the administration of test drugs in the tail-flick test. However, subcutaneous atipamezole had no significant effect on systemic morphine antinociception, and it did not attenuate morphine tolerance. CONCLUSIONS: Spinal coadministration of low doses of atipamezole augmented the antinociceptive effect of morphine in naïve and tolerant rats. Heterodimerization of µ-opioid- and α(2A)-adrenoceptors with consequent changes in function and interaction could explain these results. This also suggests an interesting explanation for the variability in opioid response and tolerance in patients experiencing stress or having an increased noradrenergic tone due to other causes, e.g., drugs.

Persistent susceptibility of cathepsin B to irreversible inhibition by nitroxyl (HNO) in the presence of endogenous nitric oxide.

Nitrosation of enzyme regulatory cysteines is one of the key posttranslational modification mechanisms of enzyme function. Frequently such modifications are readily reversible; however, cysteine proteases, such as cathepsin B, have been shown to be covalently and permanently inactivated by nitroxyl (HNO), the one-electron reduction product of NO. Owing to the high reactivity of HNO with NO, endogenous NO production could provide direct protection for the less reactive protein cysteines by scavenging HNO. Additionally, endogenous cellular production of NO could rescue enzyme function by protective nitrosation of cysteines prior to exposure to HNO. Thus, we studied the effect of endogenous NO production, induced by LPS or IFN-gamma, on inhibition of cysteine protease cathepsin B in RAW macrophages. Both LPS and IFN-gamma induce iNOS with generation of nitrate up to 9 muM in the media after a 24-h stimulation, while native RAW 264.7 macrophages neither express iNOS nor generate nitrate. After the 24-h stimulation, the HNO-releasing Angeli's salt (0-316 microM) caused dose-dependent and DTT-irreversible loss of cathepsin B activity, and induction of iNOS activity did not protect the enzyme. The lack of protection was also verified in an in vitro setup, where papain, a close structural analogue of cathepsin B, was inhibited by Angeli's salt (2.7 microM) in the presence of the NO donor DEA/NO (0-316 microM). This clearly showed that a high molar excess of DEA/NO (EC(50) 406 microM) is needed to protect papain from the DTT-irreversible covalent modification by HNO. Our results provide first evidence on a cellular level for the remarkably high sensitivity of active-site cysteines in cysteine proteases for modification by HNO.

Cathepsin B is a differentiation-resistant target for nitroxyl (HNO) in THP-1 monocyte/macrophages.

We previously showed that the one-electron reduction product of nitric oxide (NO), nitroxyl (HNO), irreversibly inhibits the proteolytic activity of the model cysteine protease papain. This result led us to investigate the differential effects of the nitrogen oxides, such as nitroxyl (HNO), NO, and in situ-generated peroxynitrite on cysteine modification-sensitive cellular proteolytic enzymes. We used Angeli's salt, diethylaminenonoate (DEA/NO), and 3-morpholinosydnoniminehydrochloride (SIN-1), as donors of HNO, NO, and peroxynitrite, respectively. In this study we evaluated their inhibitory activities on the lysosomal mammalian papain homologue cathepsin B and on the cytosolic 26S proteasome in THP-1 monocyte/macrophages after LPS activation or TPA differentiation. HNO-generating Angeli's salt caused a concentration-dependent (62 +/- 4% at 316 muM) inhibition of the 26S proteasome activity, resulting in accumulation of protein-bound polyubiquitinylated proteins in LPS-activated cells, whereas neither DEA/NO nor SIN-1 showed any effect. Angeli's salt, but not DEA/NO or SIN-1, also caused (94 +/- 2% at 316 muM) inhibition of lysosomal cathepsin B activity in LPS-activated cells. Induction of macrophage differentiation did not significantly alter the inhibitory effect of HNO on lysosomal cathepsin B activity, but protected the proteasome from HNO-induced inhibition. The protection awarded by macrophage differentiation was associated with induction of the GSH synthesis rate-limiting enzyme gamma-glutamylcysteine synthetase, as well as with increased intracellular GSH. In conclusion, HNO abrogates both lysosomal and cytosolic proteolysis in THP-1 cells. Macrophage differentiation, associated with upregulation of antioxidant defenses such as increased cellular GSH, does not protect the lysosomal cysteine protease cathepsin B from inhibition.

Nitric oxide-related species-induced protein oxidation: reversible, irreversible, and protective effects on enzyme function of papain.

Protein oxidation, irreversible modification, and inactivation may play key roles in various neurodegenerative disorders. Therefore, we studied the effects of the potentially in vivo occurring nitric oxide-related species on two different markers of protein oxidation: protein carbonyl generation on bovine serum albumine (BSA) and loss of activity of a cysteine-dependent protease, papain, in vitro by using Angeli's salt, papanonoate, SIN-1, and S-nitrosoglutathione (GSNO) as donors of nitroxyl, nitric oxide, peroxynitrite, and nitrosonium ions, respectively. Angeli's salt, SIN-1, and papanonoate (0-1000 microM) all generated a concentration-dependent increase in carbonyl formation on BSA (107, 60, and 45%, respectively). GSNO did not affect carbonyl formation. Papain was inhibited by Angeli's salt, SIN-1, papanonoate, and GSNO with IC50 values of 0.62, 2.3, 54, and 80 microM, respectively. Angeli's salt (3.16 microM)-induced papain inactivation was only partially reversible, while the effects of GSNO (316 microM) and papanonoate (316 microM) were reversible upon addition of excess DTT. The Angeli's salt-mediated DTT-irreversible inhibition of papain was prevented by GSNO or papanonoate pretreatment, hypothetically through mixed disulfide formation or S-nitrosylation of the catalytically critical thiol group of papain. These results, for the first time, compare the generation of carbonyls in proteins by Angeli's salt, papanonoate, and SIN-1. Furthermore, these results suggest that S-nitrosothiols may have a novel function in protecting critical thiols from irreversible oxidative damage.

Angeli's salt and spinal motor neuron injury.

UNLABELLED: Nitroxyl anion or its conjugate acid (NO-/HNO) and nitric oxide (NO) may both have pro-oxidative and cytotoxic properties. Superoxide dismutase (SOD) enzyme has been shown to convert reversibly HNO to NO. Mutations found in the SOD enzyme in some familial amyotrophic lateral sclerosis (ALS) patients affect redox properties of the SOD enzyme in a manner, which may affect the equilibrium between NO and HNO. Therefore, we studied the effects of HNO releasing compound, Angeli's salt (AS), on both motor and sensory functions after intrathecal administration in the lumbar spinal cord of a male rat. These functions were measured by rotarod, spontaneous activity, paw- and tail-flick tests. In addition, we compared the effect of AS to NO releasing papanonoate, old AS solution and sulphononoate in the motor performance test. The effect of intrathecal delivery of AS on the markers of the spinal cord injury and oxidative/nitrosative stress were further studied. RESULTS: Freshly prepared AS (5 or 10 micromol), but not papanonoate, caused a marked decrease in the rotarod performance 3-7 days after the intrathecal administration. The peak motor deficiency was noted 3 days after AS (5 micromol) delivery. Old, degraded, AS solution and nitrous oxide releasing sulphononoate did not decrease motor performance in the rotarod test. AS did not affect the sensory stimulus evoked responses as measured by the paw-flick and tail-flick tests. Immunohistological examination revealed that AS caused injury related changes in the expression of glial fibrillary acidic protein (GFAP), fibroblast growth factor (FGF-2) and laminins in the spinal cord. Moreover, AS increased nitrotyrosine immunoreactivity in the spinal motor neurons. Therefore, we conclude that AS, but not NO releasing papanonoate, causes motor neuron injury but does not affect the function of sensory nerves in behavioural tests.

KDI tripeptide of gamma1 laminin protects rat dopaminergic neurons from 6-OHDA induced toxicity.

Our previous studies indicate that the KDI (Lys-Asp-Ile) tripeptide of gamma1 laminin protects central neurons from mechanical trauma and excitotoxicity. At least part of the neuroprotective effect of the KDI tripeptide may be mediated by its inhibitory function on ionotropic glutamate receptors. We studied the protective effect of the KDI tripeptide against 6-hydroxy-dopamine (6-OHDA) induced neurotoxicity in a rat experimental model of Parkinson's disease (PD). We found that a single unilateral injection of the KDI tripeptide into the substantia nigra before an injection of 6-OHDA protected the dopaminergic neurons from the neurotoxicity of 6-OHDA. Compared to rats treated with 6-OHDA alone, the KDI + 6-OHDA-treated substantia nigra was relatively intact with large numbers of dopaminergic neurons present at the injection side. In the rats treated with 6-OHDA alone, no dopaminergic neurons were detected, and the substantia nigra-area at the injection side was filled with blood-containing cavities. Quantification of the rescue effect of the KDI tripeptide indicated that, in animals receiving KDI before 6-OHDA, 33% of tyrosine hydroxylase-positive dopaminergic neurons of the substantia nigra were present as compared to the contralateral non-injected side. In animals receiving 6-OHDA alone, only 1.4% of the tyrosine hydroxylase expressing dopaminergic neurons could be verified. If this much protection were achieved in humans, it would be sufficient to diminish or greatly alleviate the clinical symptoms of PD. We propose that the KDI tripeptide or its derivatives might offer a neuroprotective biological alternative for treatment of PD.

Regeneration of adult rat spinal cord is promoted by the soluble KDI domain of gamma1 laminin.

Regeneration in the central nervous system (CNS) of adult mammals is hampered by formation of a glial scar and by proteins released from the myelin sheaths of injured neuronal pathways. Our recent data indicate that the KDI (Lys-Asp-Ile) domain of gamma1 laminin neutralizes both glial- and myelin-derived inhibitory signals and promotes survival and neurite outgrowth of cultured human spinal cord neurons. We show that after complete transection of the adult rat spinal cord, animals receiving onsite infusion of the KDI domain via osmotic mini-pumps recover and are able to sustain their body weights and walk with their hindlimbs. Animals treated with placebo suffer from irreversible hindlimb paralysis. Microscopic and molecular analyses of the spinal cords indicate that the KDI domain reduces tissue damage at the lesion site and enables neurite outgrowth through the injured area to effect functional recovery of the initially paralyzed animals. That the KDI domain enhances regeneration of acute spinal cord injuries in the adult rat suggests that it may be used to promote regeneration of spinal cord injuries in humans.