Large analysis of genetic manipulations reveals an inverse correlation between initial alcohol resistance and rapid tolerance phenotypes.

Tolerance occurs when, following an initial experience with a substance, more of the substance is required subsequently to induce identical behavioral effects. Tolerance is not well-understood, and numerous researchers have turned to model organisms, particularly Drosophila melanogaster, to unravel its mechanisms. Flies have high translational relevance for human alcohol responses, and there is substantial overlap in disease-causing genes between flies and humans, including those associated with Alcohol Use Disorder. Numerous Drosophila tolerance mutants have been described; however, approaches used to identify and characterize these mutants have varied across time and labs and have mostly disregarded any impact of initial resistance/sensitivity to ethanol on subsequent tolerance development. Here, we analyzed our own, as well as data published by other labs to uncover an inverse correlation between initial ethanol resistance and tolerance phenotypes. This inverse correlation suggests that initial resistance phenotypes can explain many 'perceived' tolerance phenotypes, thus classifying such mutants as 'secondary' tolerance mutants. Additionally, we show that tolerance should be measured as a relative increase in time to sedation between an initial and second exposure rather than an absolute change in time to sedation. Finally, based on our analysis, we provide a method for using a linear regression equation to assess the residuals of potential tolerance mutants. These residuals provide predictive insight into the likelihood of a mutant being a 'primary' tolerance mutant, where a tolerance phenotype is not solely a consequence of initial resistance, and we offer a framework for understanding the relationship between initial resistance and tolerance.

Miconazole induces aneuploidy-mediated tolerance in Candida albicans that is dependent on Hsp90 and calcineurin.

Antifungal resistance and antifungal tolerance are two distinct terms that describe different cellular responses to drugs. Antifungal resistance describes the ability of a fungus to grow above the minimal inhibitory concentration (MIC) of a drug. Antifungal tolerance describes the ability of drug susceptible strains to grow slowly at inhibitory drug concentrations. Recent studies indicate antifungal resistance and tolerance have distinct evolutionary trajectories. Superficial candidiasis bothers millions of people yearly. Miconazole has been used for topical treatment of yeast infections for over 40 years. Yet, fungal resistance to miconazole remains relatively low. Here we found different clinical isolates of Candida albicans had different profile of tolerance to miconazole, and the tolerance was modulated by physiological factors including temperature and medium composition. Exposure of non-tolerant strains with different genetic backgrounds to miconazole mainly induced development of tolerance, not resistance, and the tolerance was mainly due to whole chromosomal or segmental amplification of chromosome R. The efflux gene CDR1 was required for maintenance of tolerance in wild type strains but not required for gain of aneuploidy-mediated tolerance. Heat shock protein Hsp90 and calcineurin were essential for maintenance as well as gain of tolerance. Our study indicates development of aneuploidy-mediated tolerance, not resistance, is the predominant mechanism of rapid adaptation to miconazole in C. albicans, and the clinical relevance of tolerance deserves further investigations.

Synaptic Mechanisms of Ethanol Tolerance and Neuroplasticity: Insights from Invertebrate Models.

Alcohol tolerance is a neuroadaptive response that leads to a reduction in the effects of alcohol caused by previous exposure. Tolerance plays a critical role in the development of alcohol use disorder (AUD) because it leads to the escalation of drinking and dependence. Understanding the molecular mechanisms underlying alcohol tolerance is therefore important for the development of effective therapeutics and for understanding addiction in general. This review explores the molecular basis of alcohol tolerance in invertebrate models, Drosophila and C. elegans, focusing on synaptic transmission. Both organisms exhibit biphasic responses to ethanol and develop tolerance similar to that of mammals. Furthermore, the availability of several genetic tools makes them a great candidate to study the molecular basis of ethanol response. Studies in invertebrate models show that tolerance involves conserved changes in the neurotransmitter systems, ion channels, and synaptic proteins. These neuroadaptive changes lead to a change in neuronal excitability, most likely to compensate for the enhanced inhibition by ethanol.

Immunogenicity of Atezolizumab: Influence of Testing Method and Sampling Frequency on Reported Anti-drug Antibody Incidence Rates.

Measurement of anti-drug antibodies (ADA) to assess the incidence of ADA in a clinical trial is a critical step in immunogenicity assessment during the development of a protein therapeutic. We developed novel graphical approaches to illustrate clinical trial ADA data for the PD-L1 inhibitor atezolizumab (Tecentriq) that included a systematic analysis of the impact of the timing of ADA sampling and ADA assay drug tolerance on reported ADA incidence. We found that approaches used across the industry for ADA incidence analysis provide a limited view of immunogenicity in oncology studies, where ADA detection may be confounded by both drug dosage and patient attrition. Moreover, these approaches can miss important temporal information about the immune response. Our results demonstrated that the methodology of ADA assessment for the atezolizumab program was specifically designed to capture most ADA responses to ensure accurate reporting of ADA incidence. We further showed that the use of sparse sampling and/or ADA test methods with insufficient drug tolerance may result in a significant underreporting of ADA incidence. We conclude that the comparison of ADA incidence between different drugs can be highly misleading and that a test method with appropriate sensitivity in the presence of the drug and a clinical sampling scheme that is aligned with ADA responses to a drug is required to accurately report ADA incidence.

Inhibiting spinal cord-specific hsp90 isoforms reveals a novel strategy to improve the therapeutic index of opioid treatment.

Opioids are the gold standard for the treatment of chronic pain but are limited by adverse side effects. In our earlier work, we showed that Heat shock protein 90 (Hsp90) has a crucial role in regulating opioid signaling in spinal cord; Hsp90 inhibition in spinal cord enhances opioid anti-nociception. Building on these findings, we injected the non-selective Hsp90 inhibitor KU-32 by the intrathecal route into male and female CD-1 mice, showing that morphine anti-nociceptive potency was boosted by 1.9-3.5-fold in acute and chronic pain models. At the same time, tolerance was reduced from 21-fold to 2.9 fold and established tolerance was rescued, while the potency of constipation and reward was unchanged. These results demonstrate that spinal Hsp90 inhibition can improve the therapeutic index of morphine. However, we also found that systemic non-selective Hsp90 inhibition blocked opioid pain relief. To avoid this effect, we used selective small molecule inhibitors and CRISPR gene editing to identify 3 Hsp90 isoforms active in spinal cord (Hsp90α, Hsp90ß, and Grp94) while only Hsp90α was active in brain. We thus hypothesized that a systemically delivered selective inhibitor to Hsp90ß or Grp94 could selectively inhibit spinal cord Hsp90 activity, resulting in enhanced opioid therapy. We tested this hypothesis using intravenous delivery of KUNB106 (Hsp90ß) and KUNG65 (Grp94), showing that both drugs enhanced morphine anti-nociceptive potency while rescuing tolerance. Together, these results suggest that selective inhibition of spinal cord Hsp90 isoforms is a novel, translationally feasible strategy to improve the therapeutic index of opioids.

Tsc22d3 promotes morphine tolerance in mice through the GPX4 ferroptosis pathway.

BACKGROUND: Morphine tolerance refers to gradual reduction in response to drug with continuous or repeated use of morphine, requiring higher doses to achieve same effect. METHODS: The morphine tolerance dataset GSE7762 profiles, obtained from gene expression omnibus (GEO) database, were used to identify differentially expressed genes (DEGs). Weighted Gene Co-expression Network Analysis (WGCNA) was applied to explore core modules of DEGs related to morphine tolerance. Core genes were input into Comparative Toxicogenomics Database (CTD). Animal experiments were performed to validate role of Tsc22d3 in morphine tolerance and its relationship with ferroptosis-related pathway. RESULTS: 500 DEGs were identified. DEGs were primarily enriched in negative regulation of brain development, neuronal apoptosis processes, and neurosystem development. Core gene was identified as Tsc22d3. Tsc22d3 gene-associated miRNAs were mmu-miR-196b-5p and mmu-miR-196a-5p. Compared to Non-morphine tolerant group, Tsc22d3 expression was significantly upregulated in Morphine tolerant group. Tsc22d3 expression was upregulated in Morphine tolerant+Tsc22d3_OE, expression of HIF-1alpha, GSH, GPX4 in GPX4 ferroptosis-related pathway showed a more pronounced decrease. As Tsc22d3 expression was downregulated in Morphine tolerant+Tsc22d3_KO, expression of HIF-1alpha, GSH, GPX4 in GPX4 ferroptosis-related pathway exhibited a more pronounced increase. Upregulation of Tsc22d3 in Morphine tolerant+Tsc22d3_OE led to a more pronounced increase in expression of apoptosis proteins (P53, Caspase-3, Bax, SMAC, FAS). The expression of inflammatory factors (IL6, TNF-alpha, CXCL1, CXCL2) showed a more pronounced increase with upregulated Tsc22d3 expression in Morphine tolerant+Tsc22d3_OE. CONCLUSIONS: Tsc22d3 is highly expressed in brain tissue of morphine-tolerant mice, activating ferroptosis pathway, enhancing apoptosis, promoting inflammatory responses in brain cells.

Cannabinoid CB2 receptors in primary sensory neurons are implicated in CB2 agonist-mediated suppression of paclitaxel-induced neuropathic nociception and sexually-dimorphic sparing of morphine tolerance.

Cannabinoid CB2 agonists show therapeutic efficacy without unwanted CB1-mediated side effects. The G protein-biased CB2 receptor agonist LY2828360 attenuates the maintenance of chemotherapy-induced neuropathic nociception in male mice and blocks development of morphine tolerance in this model. However, the cell types involved in this phenomenon are unknown and whether this therapeutic profile is observed in female mice has never been investigated. We used conditional deletion of CB2 receptors to determine the cell population(s) mediating the anti-allodynic and morphine-sparing effects of CB2 agonists. Anti-allodynic effects of structurally distinct CB2 agonists (LY2828360 and AM1710) were present in paclitaxel-treated CB2f/f mice and in mice lacking CB2 receptors in CX3CR1 expressing microglia/macrophages (CX3CR1CRE/+; CB2f/f), but were absent in mice lacking CB2 receptors in peripheral sensory neurons (AdvillinCRE/+; CB2f/f). The morphine-sparing effect of LY28282360 occurred in a sexually-dimorphic manner, being present in male, but not female, mice. LY2828360 treatment (3 mg/kg per day i.p. x 12 days) blocked the development of morphine tolerance in male CB2f/f and CX3CR1CRE/+; CB2f/f mice with established paclitaxel-induced neuropathy but was absent in male (or female) AdvillinCRE/+; CB2f/f mice. Co-administration of morphine with a low dose of LY2828360 (0.1 mg/kg per day i.p. x 6 days) reversed morphine tolerance in paclitaxel-treated male CB2f/f mice, but not AdvillinCRE/+; CB2f/f mice of either sex. LY2828360 (3 mg/kg per day i.p. x 8 days) delayed, but did not prevent, the development of paclitaxel-induced mechanical or cold allodynia in either CB2f/f or CX3CR1CRE/+; CB2f/f mice of either sex. Our findings have potential clinical implications.

JNK Signaling Positively Regulates Acute Ethanol Tolerance in C. elegans.

Alcohol use disorder (AUD) is a chronic neurobehavioral condition characterized by a cycle of tolerance development, increased consumption, and reinstated craving and seeking behaviors during withdrawal. Understanding the intricate mechanisms of AUD necessitates reliable animal models reflecting its key features. Caenorhabditis elegans (C. elegans), with its conserved nervous system and genetic tractability, has emerged as a valuable model organism to study AUD. Here, we employ an ethanol vapor exposure model in Caenorhabditis elegans, recapitulating AUD features while maintaining high-throughput scalability. We demonstrate that ethanol vapor exposure induces intoxication-like behaviors, acute tolerance, and ethanol preference, akin to mammalian AUD traits. Leveraging this model, we elucidate the conserved role of c-jun N-terminal kinase (JNK) signaling in mediating acute ethanol tolerance. Mutants lacking JNK signaling components exhibit impaired tolerance development, highlighting JNK's positive regulation. Furthermore, we detect ethanol-induced JNK activation in C. elegans. Our findings underscore the utility of C. elegans with ethanol vapor exposure for studying AUD and offer novel insights into the molecular mechanisms underlying acute ethanol tolerance through JNK signaling.

Negative allosteric modulation of CB1 cannabinoid receptor signaling suppresses opioid-mediated tolerance and withdrawal without blocking opioid antinociception.

The direct blockade of CB1 cannabinoid receptors produces therapeutic effects as well as adverse side-effects that limit their clinical potential. CB1 negative allosteric modulators (NAMs) represent an indirect approach to decrease the affinity and/or efficacy of orthosteric cannabinoid ligands or endocannabinoids at CB1. We recently reported that GAT358, a CB1-NAM, blocked opioid-induced mesocorticolimbic dopamine release and reward via a CB1-allosteric mechanism of action. Whether a CB1-NAM dampens opioid-mediated therapeutic effects such as analgesia or alters other unwanted opioid side-effects remain unknown. Here, we characterized the effects of GAT358 on nociceptive behaviors in the presence and absence of morphine in male rats. We examined the impact of GAT358 on formalin-evoked pain behavior and Fos protein expression, a marker of neuronal activation, in the lumbar spinal cord. We also assessed the impact of GAT358 on morphine-induced slowing of colonic transit, tolerance, and withdrawal behaviors in male mice. GAT358 attenuated morphine antinociceptive tolerance without blocking acute antinociception and reduced morphine-induced slowing of colonic motility without impacting fecal boli production. GAT358 also produced antinociception in the presence and absence of morphine in the formalin model of inflammatory nociception and reduced the number of formalin-evoked Fos protein-like immunoreactive cells in the lumbar spinal cord. Finally, GAT358 mitigated the somatic signs of naloxone-precipitated, but not spontaneous, opioid withdrawal following chronic morphine dosing. Our results support the therapeutic potential of CB1-NAMs as novel drug candidates aimed at preserving opioid-mediated analgesia while preventing their unwanted side-effects. Our studies also uncover previously unrecognized antinociceptive properties associated with an arrestin-biased CB1-NAM.

Biasing Gßγ Downstream Signaling with Gallein Inhibits Development of Morphine Tolerance and Potentiates Morphine-Induced Nociception in a Tolerant State.

Opioid analgesics are widely used as a treatment option for pain management and relief. However, the misuse of opioid analgesics has contributed to the current opioid epidemic in the United States. Prescribed opioids such as morphine, codeine, oxycodone, and fentanyl are mu-opioid receptor (MOR) agonists primarily used in the clinic to treat pain or during medical procedures, but development of tolerance limits their utility for treatment of chronic pain. Here we explored the effects of biasing Gßγ signaling on tolerance development after chronic morphine treatment in vivo. We hypothesized that biasing Gßγ signaling with gallein could prevent activation of regulatory signaling pathways that result in tolerance to antinociceptive effects of MOR agonists. Gallein has been shown to bind to Gßγ and inhibit interactions of Gßγ with phospholipase-Cß3 (PLCß3) or G-protein-coupled receptor kinase 2 (GRK2) but not G-protein inwardly rectifying potassium (GIRK) channels. In mice, morphine-induced antinociception was evaluated in the 55°C warm water tail withdrawal assay. We used two paradigms for gallein treatment: administration during and after three times-daily morphine administration. Our results show that gallein cotreatment during repeated administration of morphine decreased opioid tolerance development and that gallein treatment in an opioid-tolerant state enhanced the potency of morphine. Mechanistically, our data suggest that PLCß3 is necessary for potentiating effects of gallein in an opioid-tolerant state but not in preventing the development of tolerance. These studies demonstrate that small molecules that target Gßγ signaling could reduce the need for large doses of opioid analgesics to treat pain by producing an opioid-sparing effect. SIGNIFICANCE STATEMENT: Biasing Gßγ signaling prevents tolerance to repeated morphine administration in vivo and potentiates the antinociceptive effects of morphine in an opioid-tolerant state. Mechanistically, phospholipase-Cß is necessary for potentiating effects of gallein in an opioid-tolerant state but not in preventing the development of tolerance. This study identifies a novel treatment strategy to decrease the development of tolerance to the analgesic effects of mu-opioid receptor agonists, which are necessary to improve pain treatment and decrease the incidence of opioid use disorder.

Naïve and induced tolerance of 15 amphibian populations to three commonly applied insecticides.

Human impacts on ecological communities are pervasive and species must either move or adapt to changing environmental conditions. For environments polluted by contaminants, researchers have found hundreds of target pest species evolving increased tolerance, but we have substantially fewer cases of evolved tolerance in non-target species. When species do evolve increased tolerance, inducible tolerance can provide immediate protection and favor the evolution of increased tolerance over generations via genetic assimilation. Using a model larval amphibian (wood frogs, Rana sylvatica), we examined the tolerance of 15 populations from western Pennsylvania and eastern New York (USA), when first exposed to no pesticide or sublethal concentrations and subsequently exposed to lethal concentrations of three common insecticides (carbaryl, chlorpyrifos, and diazinon). We found high variation in naïve tolerance among the populations for all three insecticides. We also discovered that nearly half of the populations exhibited inducible tolerance, though the degree of inducible tolerance (magnitude of tolerance plasticity; MoTP) varied. We observed a cross-tolerance pattern of the populations between chlorpyrifos and diazinon, but no pattern of similar MoTP among the pesticides. With populations combined from two regions, increased tolerance was not associated with proximity to agricultural fields, but there were correlations between proximity to agriculture and MoTP. Collectively, these results suggests that amphibian populations possess a wide range of naïve tolerance to common pesticides, with many also being able to rapidly induce increased tolerance. Future research should examine inducible tolerance in a wide variety of other taxa and contaminants to determine the ubiquity of these responses to anthropogenic factors.

Tiam1-mediated maladaptive plasticity underlying morphine tolerance and hyperalgesia.

Opioid pain medications, such as morphine, remain the mainstay for treating severe and chronic pain. Prolonged morphine use, however, triggers analgesic tolerance and hyperalgesia (OIH), which can last for a long period after morphine withdrawal. How morphine induces these detrimental side effects remains unclear. Here, we show that morphine tolerance and OIH are mediated by Tiam1-coordinated synaptic structural and functional plasticity in the spinal nociceptive network. Tiam1 is a Rac1 GTPase guanine nucleotide exchange factor that promotes excitatory synaptogenesis by modulating actin cytoskeletal dynamics. We found that prolonged morphine treatment activated Tiam1 in the spinal dorsal horn and Tiam1 ablation from spinal neurons eliminated morphine antinociceptive tolerance and OIH. At the same time, the pharmacological blockade of Tiam1-Rac1 signalling prevented the development and reserved the established tolerance and OIH. Prolonged morphine treatment increased dendritic spine density and synaptic NMDA receptor activity in spinal dorsal horn neurons, both of which required Tiam1. Furthermore, co-administration of the Tiam1 signalling inhibitor NSC23766 was sufficient to abrogate morphine tolerance in chronic pain management. These findings identify Tiam1-mediated maladaptive plasticity in the spinal nociceptive network as an underlying cause for the development and maintenance of morphine tolerance and OIH and provide a promising therapeutic target to reduce tolerance and prolong morphine use in chronic pain management.

Motivation and context of concurrent stimulant and opioid use among persons who use drugs in the rural United States: a multi-site qualitative inquiry.

BACKGROUND: In recent years, stimulant use has increased among persons who use opioids in the rural U.S., leading to high rates of overdose and death. We sought to understand motivations and contexts for stimulant use among persons who use opioids in a large, geographically diverse sample of persons who use drugs (PWUD) in the rural settings. METHODS: We conducted semi-structured individual interviews with PWUD at 8 U.S. sites spanning 10 states and 65 counties. Content areas included general substance use, injection drug use, changes in drug use, and harm reduction practices. We used an iterative open-coding process to comprehensively itemize and categorize content shared by participants related to concurrent use. RESULTS: We interviewed 349 PWUD (64% male, mean age 36). Of those discussing current use of stimulants in the context of opioid use (n = 137, 39%), the stimulant most used was methamphetamine (78%) followed by cocaine/crack (26%). Motivations for co-use included: 1) change in drug markets and cost considerations; 2) recreational goals, e.g., seeking stronger effects after heightened opioid tolerance; 3) practical goals, such as a desire to balance or alleviate the effects of the other drug, including the use of stimulants to avoid/reverse opioid overdose, and/or control symptoms of opioid withdrawal; and 4) functional goals, such as being simultaneously energized and pain-free in order to remain productive for employment. CONCLUSION: In a rural U.S. cohort of PWUD, use of both stimulants and opioids was highly prevalent. Reasons for dual use found in the rural context compared to urban studies included changes in drug availability, functional/productivity goals, and the use of methamphetamine to offset opioid overdose. Education efforts and harm reduction services and treatment, such as access to naloxone, fentanyl test strips, and accessible drug treatment for combined opioid and stimulant use, are urgently needed in the rural U.S. to reduce overdose and other adverse outcomes.

Mesenchymal Stem Cells Increase Drug Tolerance of A431 Cells Only in 3D Spheroids, Not in 2D Co-Cultures.

Mesenchymal stem cells (MSCs) are an integral part of the tumor microenvironment (TME); however, their role is somewhat controversial: conflicting reports suggest that, depending on the stage of tumor development, MSCs can either support or suppress tumor growth and spread. Additionally, the influence of MSCs on drug resistance is also ambiguous. Previously, we showed that, despite MSCs proliferating significantly more slowly than cancer cells, there are chemotherapeutic drugs which proved to be similarly toxic to both cell types. Here we established 2D co-cultures and 3D co-culture spheroids from different ratios of GFP-expressing, adipose tissue-derived MSCs and A431 epidermoid carcinoma cells tagged with mCherry to investigate the effect of MSCs on cancer cell growth, survival, and drug sensitivity. We examined the cytokine secretion profile of mono- and co-cultures, explored the inner structure of the spheroids, applied MSC-(nutlin-3) and cancer cell-targeting (cisplatin) treatments separately, monitored the response with live-cell imaging and identified a new, double-fluorescent cell type emerging from these cultures. In 2D co-cultures, no effect on proliferation or drug sensitivity was observed, regardless of the changes in cytokine secretion induced by the co-culture. Conversely, 3D spheroids developed a unique internal structure consisting of MSCs, which significantly improved cancer cell survival and resilience to treatment, suggesting that physical proximity and cell-cell connections are required for MSCs to considerably affect nearby cancer cells. Our results shed light on MSC-cancer cell interactions and could help design new, better treatment options for tumors.

Natural History of Opioid Use in Naive and Tolerant Patients in Revision Total Hip Arthroplasty.

BACKGROUND: Opioid use after revision total hip arthroplasty (rTHA) has not been well characterized. The purpose of this study was to characterize preoperative, perioperative, and postoperative opioid use during rTHA. METHODS: Patients undergoing revision THA from 2010 to 2018 were screened for opioid use 3 months before revision surgery and tracked 24 months postoperatively. Patients were categorized as naïve or tolerant. Opioid prescriptions and average morphine milligram equivalents (MME) were compared between the two groups. RESULTS: One hundred twenty-four of 247 patients (50%) in the tolerant group averaged a preoperative MME of 23.7 mg/day. Postoperatively, tolerant patients received significantly higher daily MME at all time points, including at 3 months 31.4 versus 18.1 mg/day (P < 0.001), 6 months 19.9 versus 2.95 mg/day (P < 0.001), 12 months 14.3 versus 3.5 mg/day (P < 0.001), and 24 months 10.7 versus 2.17 mg/day (P < 0.001). Tolerant patients were more likely to have a prescription at 6 months (44% versus 22%), 12 months (41.4% versus 24%), and 24 months (38% versus 19.3%) (P < 0.001, P = 0.002, P < 0.001, respectively). DISCUSSION: Opioid-tolerant patients had higher postoperative MME requirements for longer recovery duration. Both groups reduced opioid use at 3 months and plateaued at 6 months. These findings can help the revision surgeon counsel patients and expectations.

Snakebites in Cameroon: Tolerance of a Snake Antivenom (Inoserp™ PAN-AFRICA) in Africa in Real-Life Conditions.

Snakebite envenomation (SBE) is a public health issue in sub-Saharan countries. Antivenom is the only etiological treatment. Excellent tolerance is essential in managing SBE successfully. This study aimed to evaluate tolerance of InoserpTM PAN-AFRICA (IPA). It was conducted on fourteen sites across Cameroon. IPA was administered intravenously and repeated at the same dose every two hours if needed. Early and late tolerance was assessed by the onset of clinical signs within two hours and at a visit two weeks or more after the first IPA administration, respectively. Over 20 months, 447 patients presenting with a snakebite were included. One dose of IPA was administered to 361 patients and repeated at least once in 106 patients. No significant difference was shown between the proportion of adverse events in patients who received IPA (266/361, 73.7%) and those who did not (69/85, 81.2%) (p = 0.95). Adverse reactions, probably attributable to IPA, were identified in four (1.1%) patients, including one severe (angioedema) and three mild. All these reactions resolved favorably. None of the serious adverse events observed in twelve patients were attributed to IPA. No signs of late intolerance were observed in 302 patients. Tolerance appears to be satisfactory. The availability of effective and well-tolerated antivenoms would reduce the duration of treatment and prevent most disabilities and/or deaths.

Pharmacological agents targeting drug-tolerant persister cells in cancer.

Current cancer therapy can be effective, but the development of drug resistant disease is the usual outcome. These drugs can eliminate most of the tumor burden but often fail to eliminate the rare, "Drug Tolerant Persister" (DTP) cell subpopulations in residual tumors, which can be referred to as "Persister" cells. Therefore, novel therapeutic agents specifically targeting or preventing the development of drug-resistant tumors mediated by the remaining persister cells subpopulations are needed. Since approximately ninety percent of cancer-related deaths occur because of the eventual development of drug resistance, identifying, and dissecting the biology of the persister cells is essential for the creation of drugs to target them. While there remains uncertainty surrounding all the markers identifying DTP cells in the literature, this review summarizes the drugs and therapeutic approaches that are available to target the persister cell subpopulations expressing the cellular markers ATP-binding cassette sub-family B member 5 (ABCB5), CD133, CD271, Lysine-specific histone demethylase 5 (KDM5), and aldehyde dehydrogenase (ALDH). Persister cells expressing these markers were selected as the focus of this review because they have been found on cells surviving following drug treatments that promote recurrent drug resistant cancer and are associated with stem cell-like properties, including self-renewal, differentiation, and resistance to therapy. The limitations and obstacles facing the development of agents targeting these DTP cell subpopulations are detailed, with discussion of potential solutions and current research areas needing further exploration.

Intravenous administration of recombinant Phα1ß: Antinociceptive properties and morphine tolerance reversal in a cancer-associated pain model.

Cancer-related pain is considered one of the most prevalent symptoms for those affected by cancer, significantly influencing quality of life and treatment outcomes. Morphine is currently employed for analgesic treatment in this case, however, chronic use of this opioid is limited by the development of analgesic tolerance and adverse effects, such as digestive and neurological disorders. Alternative therapies, such as ion channel blockade, are explored. The toxin Phα1ß has demonstrated efficacy in blocking calcium channels, making it a potential candidate for alleviating cancer-related pain. This study aims to assess the antinociceptive effects resulting from intravenous administration of the recombinant form of Phα1ß (r-Phα1ß) in an experimental model of cancer-related pain in mice, tolerant or not to morphine. The model of cancer-induced pain was used to evaluate these effects, with the injection of B16F10 cells, followed by the administration of the r-Phα1ß, and evaluation of the mechanical threshold by the von Frey test. Also, adverse effects were assessed using a score scale, the rotarod, and open field tests. Results indicate that the administration of r-Phα1ß provoked antinociception in animals with cancer-induced mechanical hyperalgesia, with or without morphine tolerance. Previous administration of r-Phα1ß was able to recover the analgesic activity of morphine in animals tolerant to this opioid. r-Phα1ß was proved safe for these parameters, as no adverse effects related to motor and behavioral activity were observed following intravenous administration. This study suggests that the concomitant use of morphine and r-Phα1ß could be a viable strategy for pain modulation in cancer patients.

Ketamine intolerance in patients on enhanced recovery after surgery protocols undergoing colorectal operations.

BACKGROUND: Ketamine is used in enhanced recovery after surgery (ERAS) protocols because of its beneficial antihyperalgesic and antitolerance effects. However, adverse effects such as hallucinations, sedation, and diplopia could limit ketamine's utility. The main objective of this study was to identify rates of ketamine side effects in postoperative patients after colorectal surgery and, secondarily, to compare short-term outcomes between patients receiving ketamine analgesia and controls. METHODS: This was a retrospective observational cohort study. Subjects were adults who underwent ERAS protocol-guided colorectal surgery at a large, integrated health system. Patients were grouped into ketamine-receiving and preketamine cohorts. Patients receiving ketamine were divided into tolerant and intolerant groups. Propensity score-adjusted models tested multivariate associations of ketamine tolerance/intolerance vs control group. RESULTS: A total of 732 patients underwent colorectal surgery within the ERAS program before ketamine's introduction (control). After ketamine's introduction, 467 patients received the medication. Intolerance was seen in 29% of ketamine recipients, and the most common side effect was diplopia. Demographics and surgical variables did not differ between cohorts. Multivariate models revealed no significant differences in hospital stays. Pain scores in the first 24 hours after surgery were slightly higher in patients receiving ketamine. Opiate consumption after surgery was lower for both ketamine tolerant and ketamine intolerant cohorts than for controls. CONCLUSION: Rates of ketamine intolerance are high, which can limit its use and potential effectiveness. Ketamine analgesia significantly reduced opiate consumption without increasing hospital stays after colorectal surgery, regardless of whether it was tolerated.