Pharmacology, Biochemistry and Behavior, Jun 1, 2021
Cannabinoid (CB) receptor agonists show robust antinociceptive effects in various pain models. Ho... more Cannabinoid (CB) receptor agonists show robust antinociceptive effects in various pain models. However, most of the clinically potent CB1 receptor-active drugs derived from cannabis are considered concerning due to psychotomimetic side effects. Selective CB receptor ligands that do not induce CNS side effects are of clinical interest. The venoms of marine snail Conus are a natural source of various potent analgesic peptides, some of which are already FDA approved. In this study we evaluated the ability of several Conus venom extracts to interact with CB1 receptor. HEK293 cells expressing CB1 receptors were treated with venom extracts and CB1 receptor internalization was analyzed by immunofluorescence. Results showed C. textile (C. Tex) and C. miles (C. Mil) samples as the most potent. These were serially subfractionated by HPLC for subsequent analysis by internalization assays and for analgesic potency evaluated in the formalin test and after peripheral nerve injury. Intrathecal injection of C. Tex and C. Mil subfractions reduced flinching/licking behavior during the second phase of formalin test and attenuated thermal and mechanical allodynia in nerve injury model. Treatment with proteolytic enzymes reduced CB1 internalization of subfractions, indicating the peptidergic nature of CB1 active component. Further HPLC purification revealed two potent antinociceptive subfractions within C. Tex with CB1 and possible CB2 activity, with mild to no side effects in the CB tetrad assessment. CB conopeptides can be isolated from these active Conus venom-derived samples and further developed as novel analgesic agents for the treatment of chronic pain using cell based or gene therapy approaches.
Traumatic brain injury (TBI), an unmet need: TBI is an alteration in brain function caused by an ... more Traumatic brain injury (TBI), an unmet need: TBI is an alteration in brain function caused by an external force with evidence of brain pathology. It could be from a bump, blow, blast or jolt to the head including penetrating the cranium. TBI is a public health concern worldwide due to its economic impact. Most TBIs are survivable, do not need hospitalization but may influence productivity. A smaller percentage of TBI due to falls or penetrating TBI (PTBI) needs hospitalization and accounts for largest fraction of TBI care costs. PTBI especially that involving firearm injury is an increasingly serious issue. In the United States, PTBI is an issue both in the military and civilian context costing more than $70–75 billion annually. PTBI has become increasingly survivable including previously lethal midline crossing of projectile due to brain trauma foundation guidelines as well as timely neurosurgical intervention. The extent of recovery is proportional to initial damage; injuries limited to single hemisphere stabilize earlier than those crossing the midline do. However, currently the consequence of surviving a PTBI is most likely to be permanent disability. Rate of disability has not changed over the past 5 decades. Almost 3.2 million Americans live with neurobehavioral disability i.e., chronic cognitive and functional impairment requiring support from their families and the State, with lifetime costs of millions of dollars per patient. The TBI lesion is dynamic with continued brain atrophy, which correlates with persistent neurological deficit and overall social outcome. Observations of post-TBI tissue loss by pathologists were confirmed by longitudinal imaging studies in living TBI survivors. Progressive volume loss was coincident with persistent neuroinflammation thought to be due to chronic microglial activation (Smith, 2013; Lee et al., 2018). In a study of veterans living with TBI spanning 4 decades, loss of tissue following PTBI was approximately 56 mL. Magnification of the primary injury via secondary mechanism underlies such volume loss and consequent disability. The PTBI penumbra (tissue surrounding the PTBI injury core) is render vulnerable by pyroptosis of chronically activated microglia. Continued pyroptosis of microglia and adjacent cells facilitate the lesion expansion into otherwise intact remote regions (Figure 1A & B). Spontaneous recovery in TBI generally takes place within the first 3 months after injury and is mainly due to neural plasticity but not endogenous reparative neurogenesis. Success in restoring an injured brain with current therapies is limited by inability of central nervous system to regenerate spontaneously. Hence, current medical treatments albeit unsuccessfully, have sought to (i) prevent neuroinflammation driven deterioration and (ii) replace lost cells. The historical failure of acute neuroprotective trials has led to alternate approaches i.e., recruit endogenous neural stem cells (NSCs) or replace via transplantation of exogenous NSCs with a goal to rebuild circuitry. Both preclinical and clinical attempts to boost endogenous NSCs have failed to repair injured brains. In addition, the concept of recruiting endogenous NSCs to repair injured brain developed in rodents may have limited scope in humans given the differences in neurogenesis rate and recruitment distances (Kassi et al., 2018). Could precise stereotactic placement of NSCs help address the unmet need and repair an injured brain?
Neuromonitoring with microdialysis has the potential for early detection of metabolic derangement... more Neuromonitoring with microdialysis has the potential for early detection of metabolic derangements associated with TBI. 1,260 microdialysis samples from 12 TBI patients were analyzed for glucose, -lactate, pyruvate, lactate/pyruvate ratio (LPR), and lactate/glucose ratio (LGR). Analytes were correlated with the Glasgow Coma Scale (GCS) before surgery and with the Glasgow Outcome Scale (GOS) at the time of discharge. The patients were divided into two groups for GCS: 3-6 and 7-9, and for GOS 1-3 and 4-5. Chi-squared test was performed for correlations. Glucose, lactate levels, and LGR were high in TBI patients with GCS 3-6 (p…
Journal of the Royal Army Medical Corps, Sep 3, 2015
While the pace of traumatic brain injury (TBI) research has accelerated, the treatment options re... more While the pace of traumatic brain injury (TBI) research has accelerated, the treatment options remain limited. Clinical trials are yet to yield successful treatment options, leading to innovative strategies to overcome the severe debilitating consequences of TBI. Stem cells may act as a potential treatment option. They have two key characteristics, the ability of self-renewal and the ability to give rise to daughter cells, which in the case of neural stem cells (NSCs) includes neurons, astrocytes and oligodendrocytes. They respond to the injury environment providing trophic support and have been shown to differentiate and integrate into the host brain. In this review, we introduce the notion of an NSC and describe the two neurogenic niches in the mammalian brain. The literature supporting the activation of an NSC in rodent models of TBI, both in vivo and in vitro, is detailed. This endogenous activation of NSCs may be augmented by exogenous transplantation of NSCs. Delivery of NSCs to assist the host nervous system has become an attractive option, with either fetal or adult NSC. This has resulted in cognitive and functional improvement in rodents, and current animal studies are using human NSCs. While no NSC clinical trials are currently ongoing for TBI, this review touches upon other neurological diseases and discuss how this may move forward into TBI.
Pharmacology, Biochemistry and Behavior, Jun 1, 2021
Cannabinoid (CB) receptor agonists show robust antinociceptive effects in various pain models. Ho... more Cannabinoid (CB) receptor agonists show robust antinociceptive effects in various pain models. However, most of the clinically potent CB1 receptor-active drugs derived from cannabis are considered concerning due to psychotomimetic side effects. Selective CB receptor ligands that do not induce CNS side effects are of clinical interest. The venoms of marine snail Conus are a natural source of various potent analgesic peptides, some of which are already FDA approved. In this study we evaluated the ability of several Conus venom extracts to interact with CB1 receptor. HEK293 cells expressing CB1 receptors were treated with venom extracts and CB1 receptor internalization was analyzed by immunofluorescence. Results showed C. textile (C. Tex) and C. miles (C. Mil) samples as the most potent. These were serially subfractionated by HPLC for subsequent analysis by internalization assays and for analgesic potency evaluated in the formalin test and after peripheral nerve injury. Intrathecal injection of C. Tex and C. Mil subfractions reduced flinching/licking behavior during the second phase of formalin test and attenuated thermal and mechanical allodynia in nerve injury model. Treatment with proteolytic enzymes reduced CB1 internalization of subfractions, indicating the peptidergic nature of CB1 active component. Further HPLC purification revealed two potent antinociceptive subfractions within C. Tex with CB1 and possible CB2 activity, with mild to no side effects in the CB tetrad assessment. CB conopeptides can be isolated from these active Conus venom-derived samples and further developed as novel analgesic agents for the treatment of chronic pain using cell based or gene therapy approaches.
Traumatic brain injury (TBI), an unmet need: TBI is an alteration in brain function caused by an ... more Traumatic brain injury (TBI), an unmet need: TBI is an alteration in brain function caused by an external force with evidence of brain pathology. It could be from a bump, blow, blast or jolt to the head including penetrating the cranium. TBI is a public health concern worldwide due to its economic impact. Most TBIs are survivable, do not need hospitalization but may influence productivity. A smaller percentage of TBI due to falls or penetrating TBI (PTBI) needs hospitalization and accounts for largest fraction of TBI care costs. PTBI especially that involving firearm injury is an increasingly serious issue. In the United States, PTBI is an issue both in the military and civilian context costing more than $70–75 billion annually. PTBI has become increasingly survivable including previously lethal midline crossing of projectile due to brain trauma foundation guidelines as well as timely neurosurgical intervention. The extent of recovery is proportional to initial damage; injuries limited to single hemisphere stabilize earlier than those crossing the midline do. However, currently the consequence of surviving a PTBI is most likely to be permanent disability. Rate of disability has not changed over the past 5 decades. Almost 3.2 million Americans live with neurobehavioral disability i.e., chronic cognitive and functional impairment requiring support from their families and the State, with lifetime costs of millions of dollars per patient. The TBI lesion is dynamic with continued brain atrophy, which correlates with persistent neurological deficit and overall social outcome. Observations of post-TBI tissue loss by pathologists were confirmed by longitudinal imaging studies in living TBI survivors. Progressive volume loss was coincident with persistent neuroinflammation thought to be due to chronic microglial activation (Smith, 2013; Lee et al., 2018). In a study of veterans living with TBI spanning 4 decades, loss of tissue following PTBI was approximately 56 mL. Magnification of the primary injury via secondary mechanism underlies such volume loss and consequent disability. The PTBI penumbra (tissue surrounding the PTBI injury core) is render vulnerable by pyroptosis of chronically activated microglia. Continued pyroptosis of microglia and adjacent cells facilitate the lesion expansion into otherwise intact remote regions (Figure 1A & B). Spontaneous recovery in TBI generally takes place within the first 3 months after injury and is mainly due to neural plasticity but not endogenous reparative neurogenesis. Success in restoring an injured brain with current therapies is limited by inability of central nervous system to regenerate spontaneously. Hence, current medical treatments albeit unsuccessfully, have sought to (i) prevent neuroinflammation driven deterioration and (ii) replace lost cells. The historical failure of acute neuroprotective trials has led to alternate approaches i.e., recruit endogenous neural stem cells (NSCs) or replace via transplantation of exogenous NSCs with a goal to rebuild circuitry. Both preclinical and clinical attempts to boost endogenous NSCs have failed to repair injured brains. In addition, the concept of recruiting endogenous NSCs to repair injured brain developed in rodents may have limited scope in humans given the differences in neurogenesis rate and recruitment distances (Kassi et al., 2018). Could precise stereotactic placement of NSCs help address the unmet need and repair an injured brain?
Neuromonitoring with microdialysis has the potential for early detection of metabolic derangement... more Neuromonitoring with microdialysis has the potential for early detection of metabolic derangements associated with TBI. 1,260 microdialysis samples from 12 TBI patients were analyzed for glucose, -lactate, pyruvate, lactate/pyruvate ratio (LPR), and lactate/glucose ratio (LGR). Analytes were correlated with the Glasgow Coma Scale (GCS) before surgery and with the Glasgow Outcome Scale (GOS) at the time of discharge. The patients were divided into two groups for GCS: 3-6 and 7-9, and for GOS 1-3 and 4-5. Chi-squared test was performed for correlations. Glucose, lactate levels, and LGR were high in TBI patients with GCS 3-6 (p…
Journal of the Royal Army Medical Corps, Sep 3, 2015
While the pace of traumatic brain injury (TBI) research has accelerated, the treatment options re... more While the pace of traumatic brain injury (TBI) research has accelerated, the treatment options remain limited. Clinical trials are yet to yield successful treatment options, leading to innovative strategies to overcome the severe debilitating consequences of TBI. Stem cells may act as a potential treatment option. They have two key characteristics, the ability of self-renewal and the ability to give rise to daughter cells, which in the case of neural stem cells (NSCs) includes neurons, astrocytes and oligodendrocytes. They respond to the injury environment providing trophic support and have been shown to differentiate and integrate into the host brain. In this review, we introduce the notion of an NSC and describe the two neurogenic niches in the mammalian brain. The literature supporting the activation of an NSC in rodent models of TBI, both in vivo and in vitro, is detailed. This endogenous activation of NSCs may be augmented by exogenous transplantation of NSCs. Delivery of NSCs to assist the host nervous system has become an attractive option, with either fetal or adult NSC. This has resulted in cognitive and functional improvement in rodents, and current animal studies are using human NSCs. While no NSC clinical trials are currently ongoing for TBI, this review touches upon other neurological diseases and discuss how this may move forward into TBI.
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Papers by Shyam Gajavelli