The long-term effects of COVID-19 on pulmonary status and quality of life

Background

Few studies have looked at how SARS-CoV-2 affects pulmonary function, exercise capacity, and health-related quality of life over time. The purpose of this study was to evaluate these characteristics in post COVID-19 subjects 1 year after recovery.

Methods

The study included two groups. The case group included post COVID-19 subjects who had recovered after a year, and the control group included healthy participants who had never tested positive for COVID-19.

Results

The study screened 90 participants, 42 of whom met the eligibility criteria. The findings revealed that the majority of post COVID-19 subjects had relatively normal lung function 1-year post-recovery. A significant reduction in DLCO (B/P%) was observed in the case group vs. control. The exercise capacity test revealed a clinically significant difference in distance walked and a significant difference in the dyspnea post-walk test in the case group compared to the control group. The case group's health-related quality of life domain scores were significantly affected in terms of energy/fatigue, general health, and physical function.

Conclusions

The post COVID-19 subjects were shown to have well-preserved lung function after 1 year. However, some degree of impairment in diffusion capacity, exercise capacity, and health-related quality of life remained.

Effects of isoflurane and urethane anesthetics on glutamate neurotransmission in rat brain using in vivo amperometry

BACKGROUND

Aspects of glutamate neurotransmission implicated in normal and pathological conditions are predominantly evaluated using in vivo recording paradigms in rats anesthetized with isoflurane or urethane. Urethane and isoflurane anesthesia influence glutamate neurotransmission through different mechanisms; however, real-time outcome measures of potassium chloride (KCl)-evoked glutamate overflow and glutamate clearance kinetics have not been compared within and between regions of the brain. In order to maintain rigor and reproducibility within the literature between the two most common methods of anesthetized in vivo recording of glutamate, we compared glutamate signaling as a function of anesthesia and brain region in the rat strain most used in neuroscience.

METHODS

In the following experiments, in vivo amperometric recordings of KCl-evoked glutamate overflow and glutamate clearance kinetics (uptake rate and T80) in the cortex, hippocampus, and thalamus were performed using glutamate-selective microelectrode arrays (MEAs) in young adult male, Sprague-Dawley rats anesthetized with either isoflurane or urethane.

RESULTS

Potassium chloride (KCl)-evoked glutamate overflow was similar under urethane and isoflurane anesthesia in all brain regions studied. Analysis of glutamate clearance determined that the uptake rate was significantly faster (53.2%, p < 0.05) within the thalamus under urethane compared to isoflurane, but no differences were measured in the cortex or hippocampus. Under urethane, glutamate clearance parameters were region-dependent, with significantly faster glutamate clearance in the thalamus compared to the cortex but not the hippocampus (p < 0.05). No region-dependent differences were measured for glutamate overflow using isoflurane.

CONCLUSIONS

These data support that amperometric recordings of KCl-evoked glutamate under isoflurane and urethane anesthesia result in similar and comparable data. However, certain parameters of glutamate clearance can vary based on choice of anesthesia and brain region. In these circumstances, special considerations are needed when comparing previous literature and planning future experiments.

Liver acts as a metabolic gate for the traumatic brain injury pathology: Protective action of thyroid hormone

Clinical evidence indicates that injury to the brain elicits systemic metabolic disturbances that contributes to the brain pathology. Since dietary fructose is metabolized in the liver, we explored mechanisms by which traumatic brain injury (TBI) and dietary fructose influence liver function and their possible repercussions to brain. Consumption of fructose contributed to the detrimental effects of TBI on liver operation, in terms of glucose and lipid metabolism, de novo lipogenesis, lipid peroxidation. Thyroid hormone (T4) is metabolized in the liver and found that T4 supply improved lipid metabolism by reducing de novo lipogenesis, lipid accumulation, lipogenic enzymes (ACC, AceCS1, FAS), lipid peroxidation in liver in response to fructose and fructose-TBI. T4 supply also helped to normalize glucose metabolism and improve insulin sensitivity. Furthermore, T4 counteracted elevations of the pro-inflammatory cytokines, Tnfα and Mcp-1 after TBI and/or fructose intake in liver and circulation. T4 also exerted an effect on isolated primary hepatocytes by potentiating phosphorylation of AMPKα and AKT substrate, AS160, leading to increased glucose uptake. In addition, T4 restored the metabolism of DHA in the liver disrupted by TBI and fructose, adding important information to optimize the action of DHA in therapeutics. The overall evidence seems to indicate that the liver works as a gate for the regulation of the effects of brain injury and foods on brain pathologies.

Effects of isoflurane and urethane anesthetics on glutamate neurotransmission in rat brain using in vivo amperometry

Aspects of glutamate neurotransmission implicated in normal and pathological conditions are often evaluated using in vivo recording paradigms in rats anesthetized with isoflurane or urethane. Urethane and isoflurane anesthesia influence glutamate neurotransmission through different mechanisms; however real-time outcome measures of potassium chloride (KCl)-evoked glutamate overflow and glutamate clearance kinetics have not been compared within and between regions of the brain. In the following experiments, in vivo amperometric recordings of KCl-evoked glutamate overflow and glutamate clearance kinetics (uptake rate and T80) in the cortex, hippocampus and thalamus were performed using glutamate-selective microelectrode arrays (MEAs) in young adult male, Sprague-Dawley rats anesthetized with isoflurane or urethane. Potassium chloride (KCl)-evoked glutamate overflow was similar under urethane and isoflurane anesthesia in all brain regions studied. Analysis of glutamate clearance determined that the uptake rate was significantly faster (53.2%, p<0.05) within the thalamus under urethane compared to isoflurane, but no differences were measured in the cortex or hippocampus. Under urethane, glutamate clearance parameters were region dependent, with significantly faster glutamate clearance in the thalamus compared to the cortex but not the hippocampus (p<0.05). No region dependent differences were measured for glutamate overflow using isoflurane. These data support that amperometric recordings of glutamate under isoflurane and urethane anesthesia result in mostly similar and comparable data. However, certain parameters of glutamate uptake vary based on choice of anesthesia and brain region. Special considerations must be given to these areas when considering comparison to previous literature and when planning future experiments.

Aging with TBI vs. Aging: 6-month temporal profiles for neuropathology and astrocyte activation converge in behaviorally relevant thalamocortical circuitry of male and female rats

Traumatic brain injury (TBI) manifests late-onset and persisting clinical symptoms with implications for sex differences and increased risk for the development of age-related neurodegenerative diseases. Few studies have evaluated chronic temporal profiles of neuronal and glial pathology that include sex as a biological variable. After experimental diffuse TBI, late-onset and persisting somatosensory hypersensitivity to whisker stimulation develops at one-month post-injury and persists to at least two months post-injury in male rats, providing an in vivo model to evaluate the temporal profile of pathology responsible for morbidity. Whisker somatosensation is dependent on signaling through the thalamocortical relays of the whisker barrel circuit made up of glutamatergic projections between the ventral posteromedial nucleus of the thalamus (VPM) and primary somatosensory barrel cortex (S1BF) with inhibitory (GABA) innervation from the thalamic reticular nucleus (TRN) to the VPM. To evaluate the temporal profiles of pathology, male and female Sprague Dawley rats ( n = 5-6/group) were subjected to sham surgery or midline fluid percussion injury (FPI). At 7-, 56-, and 168-days post-injury (DPI), brains were processed for amino-cupric silver stain and glial fibrillary acidic protein (GFAP) immunoreactivity, where pixel density of staining was quantified to determine the temporal profile of neuropathology and astrocyte activation in the VPM, S1BF, and TRN. FPI induced significant neuropathology in all brain regions at 7 DPI. At 168 DPI, neuropathology remained significantly elevated in the VPM and TRN, but returned to sham levels in the S1BF. GFAP immunoreactivity was increased as a function of FPI and DPI, with an FPI × DPI interaction in all regions and an FPI × Sex interaction in the S1BF. The interactions were driven by increased GFAP immunoreactivity in shams over time in the VPM and TRN. In the S1BF, GFAP immunoreactivity increased at 7 DPI and declined to age-matched sham levels by 168 DPI, while GFAP immunoreactivity in shams significantly increased between 7 and 168 days. The FPI × Sex interaction was driven by an overall greater level of GFAP immunoreactivity in FPI males compared to FPI females. Increased GFAP immunoreactivity was associated with an increased number of GFAP-positive soma, predominantly at 7 DPI. Overall, these findings indicate that FPI, time post-injury, sex, region, and aging with injury differentially contribute to chronic changes in neuronal pathology and astrocyte activation after diffuse brain injury. Thus, our results highlight distinct patterns of pathological alterations associated with the development and persistence of morbidity that supports chronic neuropathology, especially within the thalamus. Further, data indicate a convergence between TBI-induced and age-related pathology where further investigation may reveal a role for divergent astrocytic phenotypes associated with increased risk for neurodegenerative diseases.

Drosophila as a model to explore secondary injury cascades after traumatic brain injury

Drosophilae are emerging as a valuable model to study traumatic brain injury (TBI)-induced secondary injury cascades that drive persisting neuroinflammation and neurodegenerative pathology that imposes significant risk for long-term neurological deficits. As in mammals, TBI in Drosophila triggers axonal injury, metabolic crisis, oxidative stress, and a robust innate immune response. Subsequent neurodegeneration stresses quality control systems and perpetuates an environment for neuroprotection, regeneration, and delayed cell death via highly conserved cell signaling pathways. Fly injury models continue to be developed and validated for both whole-body and head-specific injury to isolate, evaluate, and modulate these parallel pathways. In conjunction with powerful genetic tools, the ability for longitudinal evaluation, and associated neurological deficits that can be tested with established behavioral tasks, Drosophilae are an attractive model to explore secondary injury cascades and therapeutic intervention after TBI. Here, we review similarities and differences between mammalian and fly pathophysiology and highlight strategies for their use in translational neurotrauma research.

Sex-Dependent Pathology in the HPA Axis at a Sub-acute Period After Experimental Traumatic Brain Injury

Over 2.8 million traumatic brain injuries (TBIs) are reported in the United States annually, of which, over 75% are mild TBIs with diffuse axonal injury (DAI) as the primary pathology. TBI instigates a stress response that stimulates the hypothalamic-pituitary-adrenal (HPA) axis concurrently with DAI in brain regions responsible for feedback regulation. While the incidence of affective symptoms is high in both men and women, presentation is more prevalent and severe in women. Few studies have longitudinally evaluated the etiology underlying late-onset affective symptoms after mild TBI and even fewer have included females in the experimental design. In the experimental TBI model employed in this study, evidence of chronic HPA dysregulation has been reported at 2 months post-injury in male rats, with peak neuropathology in other regions of the brain at 7 days post-injury (DPI). We predicted that mechanisms leading to dysregulation of the HPA axis in male and female rats would be most evident at 7 DPI, the sub-acute time point. Young adult age-matched male and naturally cycling female Sprague Dawley rats were subjected to midline fluid percussion injury (mFPI) or sham surgery. Corticotropin releasing hormone, gliosis, and glucocorticoid receptor (GR) levels were evaluated in the hypothalamus and hippocampus, along with baseline plasma adrenocorticotropic hormone (ACTH) and adrenal gland weights. Microglial response in the paraventricular nucleus of the hypothalamus indicated mild neuroinflammation in males compared to sex-matched shams, but not females. Evidence of microglia activation in the dentate gyrus of the hippocampus was robust in both sexes compared with uninjured shams and there was evidence of a significant interaction between sex and injury regarding microglial cell count. GFAP intensity and astrocyte numbers increased as a function of injury, indicative of astrocytosis. GR protein levels were elevated 30% in the hippocampus of females in comparison to sex-matched shams. These data indicate sex-differences in sub-acute pathophysiology following DAI that precede late-onset HPA axis dysregulation. Further understanding of the etiology leading up to late-onset HPA axis dysregulation following DAI could identify targets to stabilize feedback, attenuate symptoms, and improve efficacy of rehabilitation and overall recovery.

Traumatic Brain Injury-Induced Sex-Dependent Changes in Late-Onset Sensory Hypersensitivity and Glutamate Neurotransmission

Women approximate one-third of the annual 2.8 million people in the United States who sustain traumatic brain injury (TBI). Several clinical reports support or refute that menstrual cycle-dependent fluctuations in sex hormones are associated with severity of persisting post-TBI symptoms. Previously, we reported late-onset sensory hypersensitivity to whisker stimulation that corresponded with changes in glutamate neurotransmission at 1-month following diffuse TBI in male rats. Here, we incorporated intact age-matched naturally cycling females into the experimental design while monitoring daily estrous cycle. We hypothesized that sex would not influence late-onset sensory hypersensitivity and associated in vivo amperometric extracellular recordings of glutamate neurotransmission within the behaviorally relevant thalamocortical circuit. At 28 days following midline fluid percussion injury (FPI) or sham surgery, young adult Sprague-Dawley rats were tested for hypersensitivity to whisker stimulation using the whisker nuisance task (WNT). As predicted, both male and female rats showed significantly increased sensory hypersensitivity to whisker stimulation after FPI, with females having an overall decrease in whisker nuisance scores (sex effect), but no injury and sex interaction. In males, FPI increased potassium chloride (KCl)-evoked glutamate overflow in primary somatosensory barrel cortex (S1BF) and ventral posteromedial nucleus of the thalamus (VPM), while in females the FPI effect was discernible only within the VPM. Similar to our previous report, we found the glutamate clearance parameters were not influenced by FPI, while a sex-specific effect was evident with female rats showing a lower uptake rate constant both in S1BF and VPM and longer clearance time (in S1BF) in comparison to male rats. Fluctuations in estrous cycle were evident among brain-injured females with longer diestrus (low circulating hormone) phase of the cycle over 28 days post-TBI. Together, these findings add to growing evidence indicating both similarities and differences between sexes in a chronic response to TBI. A better understanding of the influence of gonadal hormones on behavior, neurotransmission, secondary injury and repair processes after TBI is needed both clinically and translationally, with potential impact on acute treatment, rehabilitation, and symptom management.

Approaches to Monitor Circuit Disruption after Traumatic Brain Injury: Frontiers in Preclinical Research

Mild traumatic brain injury (TBI) often results in pathophysiological damage that can manifest as both acute and chronic neurological deficits. In an attempt to repair and reconnect disrupted circuits to compensate for loss of afferent and efferent connections, maladaptive circuitry is created and contributes to neurological deficits, including post-concussive symptoms. The TBI-induced pathology physically and metabolically changes the structure and function of neurons associated with behaviorally relevant circuit function. Complex neurological processing is governed, in part, by circuitry mediated by primary and modulatory neurotransmitter systems, where signaling is disrupted acutely and chronically after injury, and therefore serves as a primary target for treatment. Monitoring of neurotransmitter signaling in experimental models with technology empowered with improved temporal and spatial resolution is capable of recording in vivo extracellular neurotransmitter signaling in behaviorally relevant circuits. Here, we review preclinical evidence in TBI literature that implicates the role of neurotransmitter changes mediating circuit function that contributes to neurological deficits in the post-acute and chronic phases and methods developed for in vivo neurochemical monitoring. Coupling TBI models demonstrating chronic behavioral deficits with in vivo technologies capable of real-time monitoring of neurotransmitters provides an innovative approach to directly quantify and characterize neurotransmitter signaling as a universal consequence of TBI and the direct influence of pharmacological approaches on both behavior and signaling.

Bacopa monnieri Supplements Offset Paraquat-Induced Behavioral Phenotype and Brain Oxidative Pathways in Mice

BACKGROUND

Parkinson's Disease (PD) is characterized by alterations in cerebellum and basal ganglia functioning with corresponding motor deficits and neuropsychiatric symptoms. Involvement of oxidative dysfunction has been implicated for the progression of PD, and environmental neurotoxin exposure could influence such behavior and psychiatric pathology. Assessing dietary supplementation strategies with naturally occurring phytochemicals to reduce behavioral anomalies associated with neurotoxin exposure would have major clinical importance. The present investigation assessed the influence of Bacopa monneri (BM) on behaviors considered to reflect anxiety-like state and motor function as well as selected biochemical changes in brain regions of mice chronically exposed to ecologically relevant herbicide, paraquat (PQ).

MATERIALS & METHODS

Male mice (4-week old, Swiss) were daily provided with oral supplements of standardized BM extract (200 mg/kg body weight/day; 3 weeks) and PQ (10 mg/kg, i.p. three times a week; 3 weeks).

RESULTS

We found that BM supplementation significantly reversed the PQ-induced reduction of exploratory behavior, gait abnormalities (stride length and mismatch of paw placement) and motor impairment (rotarod performance). In a separate study, BM administration prevented the reduction in dopamine levels and reversed cholinergic activity in brain regions important for motor (striatum) pathology. Further, in mitochondria, PQ-induced decrease in succinate dehydrogenase (SDH) activity and energy charge (MTT reduction), was restored with BM supplementation.

CONCLUSION

These findings suggest that BM supplementation mitigates paraquat-induced behavioral deficits and brain oxidative stress in mice. However, further investigations would enable us to identify specific molecular mechanism by which BM influences behavioural pathology.

Blueberry Supplementation Mitigates Altered Brain Plasticity and Behavior after Traumatic Brain Injury in Rats

SCOPE

Traumatic brain injury (TBI) compromises neuronal function required for hippocampal synaptic plasticity and cognitive function. Despite the high consumption of blueberries, information about its effects on brain plasticity and function under conditions of brain trauma is limited. The efficacy of dietary blueberry (BB) supplementation to mitigate the effects of TBI on plasticity markers and associated behavioral function in a rodent model of concussive injury are assessed.

METHODS AND RESULTS

Rats were maintained on a diet supplemented with blueberry (BB, 5% w/w) for 2 weeks after TBI. It is found that BB supplementation mitigated a loss of spatial learning and memory performance after TBI, and reduced the effects of TBI on anxiety-like behavior. BB supplementation prevents a reduction of molecules associated with the brain-derived neurotrophic factor (BDNF) system action on learning and memory such as cyclic-AMP response element binding factor (CREB), calcium/calmodulin-dependent protein kinase II (CaMKII). In addition, BB supplementation reverses an increase of the lipid peroxidation byproduct 4-hydroxy-nonenal (4-HNE) after TBI. Importantly, synaptic and neuronal signaling regulators change in proportion with the memory performance, suggesting an association between plasticity markers and behavior.

CONCLUSION

Data herein indicate that BB supplementation has a beneficial effect in mitigating the acute aspects of the TBI pathology.

Oral supplements of combined fructo- and xylo-oligosaccharides during perinatal period significantly offsets acrylamide-induced oxidative impairments and neurotoxicity in rats

Fetal and early childhood exposure to low levels of chemicals formed in foods during heating, especially acrylamide (ACR) is of increased concern due to developmental neurotoxicity. The neurodevelopment during perinatal period is critical and evidence suggests that the gut microbiota plays a major role in shaping brain development and behavior. Pregnant Wistar rats provided with oral supplements a combination of fructo- and xylo-oligosaccharides (FOS + XOS, 3 g/kg/day) from gestation day 0 (GD 0) to postnatal day 21 (PND 21) were exposed to ACR (100 ppm, GD 6 to PND 21) in drinking water. While ACR exposure caused a significant reduction in the maternal gestational/ lactational body weight, preweaning body weights and behavioral alterations among male offspring, combination supplement of FOS + XOS had no significant effect. However, significantly diminished antioxidant enzyme (SOD and CAT) activities in the maternal and offspring brain were restored among rats given FOS + XOS supplementation. The prebiotic supplementation normalized elevated nitric oxide levels in the cerebellum of the offspring born to ACR exposed rats. Furthermore, prebiotics restored the activity of acetylcholinesterase (AChE) and improved the levels of dopamine (DA) in the maternal cortex. The protective effect of prebiotic supplementation was also discernible in the mitochondrial fraction of maternal brain regions. These findings suggest that prebiotic supplementation during pregnancy may be useful in attenuating the perinatal toxic effects associated with neurotoxin exposure.

7,8-Dihydroxyflavone facilitates the action exercise to restore plasticity and functionality: Implications for early brain trauma recovery

Metabolic dysfunction accompanying traumatic brain injury (TBI) severely impairs the ability of injured neurons to comply with functional demands. This limits the success of rehabilitative strategies by compromising brain plasticity and function, and highlights the need for early interventions to promote energy homeostasis. We sought to examine whether the TrkB agonist, 7,8-dihydroxyflavone (7,8-DHF) normalizes brain energy deficits and reestablishes more normal patterns of functional connectivity, while enhancing the effects of exercise during post-TBI period. Moderate fluid percussion injury (FPI) was performed and 7,8-DHF (5mg/kg, i.p.) was administered in animals subjected to FPI that either had access to voluntary wheel running for 7days after injury or were sedentary. Compared to sham-injured controls, TBI resulted in reduced hippocampal activation of the BDNF receptor TrkB and associated CREB, reduced levels of plasticity markers GAP-43 and Syn I, as well as impaired memory as indicated by the Barnes maze task. While 7,8-DHF treatment and exercise individually mitigated TBI-induced effects, administration of 7,8-DHF concurrently with exercise facilitated memory performance and augmented levels of markers of cell energy metabolism viz., PGC-1α, COII and AMPK. In parallel to these findings, resting-state functional MRI (fMRI) acquired at 2weeks after injury showed that 7,8-DHF with exercise enhanced hippocampal functional connectivity, and suggests 7,8-DHF and exercise to promote increases in functional connectivity. Together, these findings indicate that post-injury 7,8-DHF treatment promotes enhanced levels of cell metabolism, synaptic plasticity in combination with exercise increases in brain circuit function that facilitates greater physical rehabilitation after TBI.

Aqueous extract of tomato seeds attenuates rotenone-induced oxidative stress and neurotoxicity in Drosophila melanogaster

BACKGROUND

Tomato seeds, a major by-product from the food processing industry, constitute a rich source of bioactives and a large population consumes tomato (either in raw or cooked form). In the present study, initially we assessed the antioxidant activity of aqueous extract of tomato seeds (TSE) in selected chemical systems and further explored the neuroprotective effects of TSE utilising the rotenone (ROT) model of neurotoxicity in Drosophila.

RESULTS

Adult male flies (Oregon K) were fed TSE-enriched medium (0.1-0.2%) with or without ROT (500 µmol L(-1)) for 7 days. The propensity of TSE to protect flies against ROT-induced lethality, locomotor phenotype, oxidative stress and neurotoxicity was investigated. TSE offered marked protection against ROT-induced mortality, while survivors exhibited improved locomotor phenotype. TSE significantly attenuated ROT-induced oxidative stress, mitochondrial dysfunctions, protein carbonyls content, restored the cholinergic function and dopamine levels.

CONCLUSION

We hypothesise that the efficacy of tomato seed extract to attenuate ROT-mediated neurotoxicity may be largely related to the combined antioxidant activity of bioactives resulting in abrogation of oxidative stress and mitochondrial dysfunction. More importantly, our approach provides an experimental paradigm to rapidly assess the potential neuroprotective effects of common dietary components employing Drosophila, since it corroborates previous evidence in a mouse model.

Standardized Bacopa monnieri extract ameliorates acute paraquat-induced oxidative stress, and neurotoxicity in prepubertal mice brain

OBJECTIVES

Bacopa monnieri (BM), an ayurvedic medicinal plant, has attracted considerable interest owing to its diverse neuropharmacological properties. Epidemiological studies have shown significant correlation between paraquat (PQ) exposure and increased risk for Parkinson's disease in humans. In this study, we examined the propensity of standardized extract of BM to attenuate acute PQ-induced oxidative stress, mitochondrial dysfunctions, and neurotoxicity in the different brain regions of prepubertal mice.

METHODS

To test this hypothesis, prepubertal mice provided orally with standardized BM extract (200 mg/kg body weight/day for 4 weeks) were challenged with an acute dose (15 mg/kg body weight, intraperitoneally) of PQ after 3 hours of last dose of extract. Mice were sacrificed after 48 hours of PQ injection, and different brain regions were isolated and subjected to biochemical determinations/quantification of central monoamine (dopamine, DA) levels (by high-performance liquid chromatography).

RESULTS

Oral supplementation of BM for 4 weeks resulted in significant reduction in the basal levels of oxidative markers such as reactive oxygen species (ROS), malondialdehyde (MDA), and hydroperoxides (HP) in various brain regions. PQ at the administered dose elicited marked oxidative stress within 48 hours in various brain regions of mice. However, BM prophylaxis significantly improved oxidative homeostasis by restoring PQ-induced ROS, MDA, and HP levels and also by attenuating mitochondrial dysfunction. Interestingly, BM supplementation restored the activities of cholinergic enzymes along with the restoration of striatal DA levels among the PQ-treated mice.

DISCUSSION

Based on these findings, we infer that BM prophylaxis renders the brain resistant to PQ-mediated oxidative perturbations and thus may be better exploited as a preventive approach to protect against oxidative-mediated neuronal dysfunctions.

Probiotic attributes, antioxidant, anti-inflammatory and neuromodulatory effects of Enterococcus faecium CFR 3003: in vitro and in vivo evidence

Accumulating evidence suggests that probiotic bacteria play a vital role in modulating various aspects integral to the health and well-being of humans. In the present study, probiotic attributes and the antioxidant, anti-inflammatory and neuromodulatory potential of Enterococcus faecium CFR 3003 were investigated by employing suitable model systems. E. faecium exhibited robust resistance to gastrointestinal stress conditions as it could withstand acid stress at pH 1.5, 2 and 3. The bacterium also survived at a bile salt concentration of 0.45 %, and better tolerance was observed towards pepsin and trypsin. E. faecium produced lactic acid as a major metabolic product, followed by butyric acid. Lyophilized cell-free supernatant (LCS) of E. faecium exhibited significant antioxidant capacity evaluated against 1,1-diphenyl-2-picryl-hydrazyl, ascorbate auto-oxidation, oxygen radical absorbance and reducing power. Interestingly, E. faecium, Lactobacillus rhamnosus GG MTCC 1408 and LCS showed a significant anti-inflammatory effect by negatively modulating TNF-α production and upregulating IL-10 levels in LPS-stimulated macrophage cell lines. In an in vivo mice model, the propensity of probiotic supplements to modulate endogenous oxidative markers and redox status in brain regions was assessed. Young mice provided with oral supplements (daily for 28 days) of E. faecium and L. rhamnosus exhibited diminished oxidative markers in the brain and enhanced activities of antioxidant enzymes with a concomitant increase in γ-aminobutyric acid and dopamine levels. Collectively, our findings clearly suggest the propensity of these bacteria to protect against tissue damage mediated through free radicals and inflammatory cytokines. Although the underlying molecular mechanisms need further studies, it is tempting to speculate that probiotics confer a neuroprotective advantage in vivo against oxidative damage-mediated neurodegenerative conditions.

Inulin supplementation during gestation mitigates acrylamide-induced maternal and fetal brain oxidative dysfunctions and neurotoxicity in rats

Accumulating evidence suggests that the developing brain is more susceptible to a variety of chemicals. Recent studies have shown a link between the enteric microbiota and brain function. While supplementation of non-digestible oligosaccharides during pregnancy has been demonstrated to positively influence human health mediated through stimulation of beneficial microbiota, our understanding on their neuromodulatory propensity is limited. In the present study, our primary focus was to examine whether supplementation of inulin (a well known fructan) during gestation can abrogate acrylamide (ACR)-induced oxidative impairments and neurotoxicity in maternal and fetal brain of rats. Initially, in a dose-determinative study, we recapitulated the impact of ACR exposure during gestation days (GD 6-19) on gestational parameters, extent of oxidative impairments in brain (maternal/fetal), cholinergic function and neurotoxicity. Subsequently, pregnant rats orally (gavage) administered with inulin (IN, 2 g/kg/day in two equal installments) supplements during gestation days (GD 0-19) were exposed to ACR (200 ppm) in drinking water. IN supplements significantly attenuated ACR-induced changes in exploratory activity (reduced open field exploration) measured on GD 14. Further, IN restored the placental weights among ACR exposed dams. Analysis of biochemical markers revealed that IN supplements effectively offset ACR associated oxidative stress not only in the maternal brain, but in the fetal brain as well. Elevated levels of protein carbonyls in maternal brain regions were completely normalized with IN supplements. More importantly, IN supplements significantly augmented the number of Bifidobacteria in the cecum of ACR rats which correlated well with the neurorestorative effect as evidenced by restored dopamine levels in the maternal cortex and fetal brain acetylcholinesterase activity among ACR-exposed dams. Further, IN supplements also conferred significant protection against mitochondrial dysfunction induced by ACR in both milieus. Although the precise mechanism/s by which IN supplements during pregnancy attenuate ACR induced neurotoxic impact merits further investigations, we hypothesize that it may mediate through enhanced enteric microbiota and abrogation of oxidative stress. Further, our study provides an experimental approach to explore the neuroprotective role of prebiotic oligosaccharides during pregnancy in reducing the adverse impact of developmental neurotoxicants.

Design and optimization of clotrimazole–hydroxypropyl-β-cyclodextrin bioadhesive vaginal tablets using Anacardium occidentale gum by 32 factorial design

Clotrimazole (CTZ), a BCS class II drug, is widely employed in the treatment of vaginal candidiasis.

Role of imprint cytology in intra operative diagnosis of thyroid lesions

Intra-operative imprint cytology is an important diagnostic modality in the diagnosis of thyroid lesions. A correct intra-operative diagnosis helps eliminate the need for second surgery.

AIM

To study diagnostic accuracy of imprint cytology and to compare the imprint cytology results with that of the corresponding paraffin section diagnosis in thyroidectomy cases.

MATERIALS AND METHODS

This is a prospective study of 84 patients who have undergone thyroidectomies over a period of one year at the Department of Surgery, Thiruvananthapuram, Kerala, India. The intraoperative imprint cytology smears were stained by Papanicolaou method. The imprint cytology interpretation was later compared with the paraffin section diagnosis.

RESULTS

Of the 84 patients using haematoxylin and eosin stained histopathology sections as the gold standard, the diagnostic sensitivity of imprint cytology was 75% and specificity was 100%. Positive predictive value was 100%. Negative predictive value was 98.74%.

CONCLUSIONS

Imprint cytology has high sensitivity and specificity in diagnosing lesions of the thyroid. The problems faced were in diagnosing follicular carcinomas and differentiating low grade lymphoma from lymphocytic thyroiditis. Imprint cytology is a simple, reliable diagnostic technique. It has high sensitivity and specificity in intra-operative diagnosis of lesions of thyroid. In spite of the advent of newer diagnostic modalities like frozen sections, imprint cytology still holds its unique position in the current perspective.

A new solid oral tablet formulation of posaconazole: a randomized clinical trial to investigate rising single- and multiple-dose pharmacokinetics and safety in healthy volunteers

Objectives

Posaconazole is an extended-spectrum triazole with proven efficacy as antifungal treatment and prophylaxis. The marketed oral suspension should be taken with food to maximize systemic absorption. A new solid oral tablet has been developed with improved bioavailability that can be administered without regard to food. The aim of this study was to evaluate rising single- and multiple-dose pharmacokinetics, safety and tolerability of the new tablet.

Methods

This was a single-centre, randomized, placebo-controlled, Phase I, rising single- and multiple-dose study of healthy subjects aged 18–65 years who received a posaconazole tablet as 200 mg once daily, 200 mg twice daily or 400 mg once daily. The 24 subjects were studied in two cohorts of 12 subjects each (9 active and 3 placebo).

Results

After single or multiple oral dose administration of posaconazole tablets (200 and 400 mg), exposure increased in a dose-related manner. Peak posaconazole concentrations were attained at a median T_max of 4–5 h. Mean half-life was similar for 200 and 400 mg posaconazole doses (25 and 26 h). The accumulation ratio upon multiple doses over 8 days was ∼3 for 200 and 400 mg once daily and ∼5 for 200 mg twice daily. C_avg values exceeded 1300 ng/mL. The posaconazole oral tablet was safe and well tolerated, although mild, transient elevations in liver function were reported in some patients.

Conclusions

Posaconazole exposure increased in a dose-related manner. The pharmacokinetics of this new solid oral tablet of posaconazole supports the clinical evaluation of once-daily dosing regimens for fungal infections.

Population pharmacokinetics of posaconazole in neutropenic patients receiving chemotherapy for acute myelogenous leukemia or myelodysplastic syndrome

OBJECTIVE

The relationship between patient characteristics and posaconazole exposures was evaluated in a population pharmacokinetic (PK) model using trial data from neutropenic patients administered oral posaconazole suspension as antifungal prophylaxis.

METHODS

Data were analyzed using nonlinear mixed-effects modeling. Covariates were tested using the forward addition, Objective Function (OF) cut-off of 3.84, followed by the backward elimination (OF cut-off 10.88) steps in NONMEM. These covariates included demographics, mucositis, neutropenia, vomiting, diarrhea, proton pump inhibitor (PPI) or H(2)-receptor antagonist usage and baseline bilirubin or baseline gamma-glutamyl transferase (GGT) levels > or =2 x upper limit of normal (ULN). A correlation between posaconazole PK and the occurrence of invasive fungal infection (IFI) was also examined.

RESULTS

Statistically significant associations were demonstrated between posaconazole PK and diarrhea, PPI intake, race, and baseline GGT and bilirubin levels. These covariates did not predominate in patients who developed IFI.

CONCLUSION

This analysis provides information regarding the correlation of patient covariates with posaconazole exposures estimated in a clinical setting. The results of this analysis agree with previously reported analyses. However, because of the successful prophylaxis and the low number of posaconazole-treated patients with IFI proven or probable (IFIPP), the absence of a statistically significant relationship between IFIPP and exposure may not mean this relationship does not exist. A meta-analysis of several efficacy trials or exploring alternate composite endpoints for efficacy may be needed to answer this question.

Evaluation of the pharmacokinetics of posaconazole and rifabutin following co-administration to healthy men

OBJECTIVE

Posaconazole is a triazole antifungal agent for the treatment and prophylaxis of invasive fungal infections. This non-randomized, open-label, parallel-group, multiple-dose, drug-interaction study was conducted to evaluate the pharmacokinetics of posaconazole and rifabutin following co-administration to healthy subjects.

METHODS

Subjects were assigned to treatment groups: Group 1 (posaconazole, 200-mg tablet once daily for 10 days) or Group 2 (rifabutin, 300-mg capsule once daily for 17 days [Days -7 to 10] co-administered with posaconazole, 200 mg tablet once daily for 10 days [Days 1-10]). Posaconazole was administered after rifabutin steady-state was reached. Individual plasma concentration-time data for posaconazole (Day 10, Groups 1 and 2) and rifabutin (Days -1 and 10, Group 2) were analyzed using model-independent methods.

RESULTS

Twenty-four men were enrolled in the study. All subjects in Group 1 completed the study; however, four subjects in Group 2 discontinued because of adverse events. When co-administered with rifabutin, posaconazole maximum plasma concentration (C(max)) and area under the plasma concentration-time curve over the dosing interval (AUC([tau])) were reduced 43% (p = 0.005) and 49% (p = 0.008), respectively. Conversely, rifabutin C(max) and AUC([tau]) increased 31% (p = 0.016) and 72% (p < 0.001), respectively, when co-administered with posaconazole.

CONCLUSION

Based on the reduced exposure to posaconazole observed in the limited number of subjects in this study and the increased risk for adverse events associated with elevated rifabutin concentrations, concomitant use of rifabutin and posaconazole should be avoided unless the benefit outweighs the risk.

A profile of HIV infection / AIDS related knowledge among female students of Kanpur district, India

INTRODUCTION

HIV/AIDS, a social disease took pandemic form within a short span of time affecting 40 million people through the globe. Adults of the developing countries are the main victim of the disease contributing to 95% of the total world's HIV infection and 90% death. In the absence of effective cure to this disease, it can be very easily prevented by IEC activities regarding behavioural changes.

OBJECTIVES

To assess the level of correct knowledge about HIV/AIDS and the misconceptions associated with it among girl students of Kanpur district.

MATERIALS AND METHODOLOGY

This is a baseline cross-sectional, questionnaire based study conducted among female students of technical and non-technical institutions of Kanpur district UP in 2001.

RESULTS

Though the causative agent and correct mode of acquiring infection was not known to most of the students yet significant proportion had adequate knowledge about the vulnerable age group that is youth as stated by (72.90%) of the respondents. Knowledge regarding correct modes of transmission of infections (82.78%), high risk groups (82.88%) and common symptoms of disease (80.11%) was satisfactory.

DISCUSSION

The finding of the present study was satisfactory and consistent with previous research findings. In paradox to their knowledge, deeply rooted misconception related to transmission of infection also surfaced and was more prevalent in technical than non technical students. These misconceptions need to be corrected to prevent the spread of the infection.

CONCLUSION

The knowledge of the study group was quite satisfactory for most of the variables like vulnerable age, modes of transmission, sexual and behavioural practices and common symptoms of the disease. However, misconceptions were also very high and almost equally present in technical and non-technical students. Though, as already stated, the technical students had better knowledge than non-technical ones.

Pharmacokinetics, safety, and efficacy of posaconazole in patients with persistent febrile neutropenia or refractory invasive fungal infection

The pharmacokinetic profiles, safety, and efficacies of different dosing schedules of posaconazole oral suspension in patients with possible, probable, and proven refractory invasive fungal infection (rIFI) or febrile neutropenia (FN) were evaluated in a multicenter, open-label, parallel-group study. Sixty-six patients with FN and 32 patients with rIFI were randomly assigned to one of three posaconazole regimens: 200 mg four times a day (q.i.d.) for nine doses, followed by 400 mg twice a day (b.i.d.); 400 mg q.i.d. for nine doses, followed by 600 mg b.i.d.; or 800 mg b.i.d. for five doses, followed by 800 mg once a day (q.d.). Therapy was continued for up to 6 months in patients with rIFI or until neutrophil recovery occurred in patients with FN. The 400-mg-b.i.d. dose provided the highest overall mean exposure, with 135% (P = 0.0004) and 182% (P < 0.0001) greater exposure than the 600-mg-b.i.d. and 800-mg-q.d. doses, respectively. However, exposure in allogeneic bone marrow transplant (BMT) recipients (n = 12) was 52% lower than in non-BMT patients. Treatment-related adverse events (occurring in 24% of patients) were mostly gastrointestinal in nature. Twenty-four percent of patients had adverse events leading to premature discontinuation (none were treatment related). In efficacy-evaluable patients, successful clinical response was observed in 43% with rIFI (56% of patients receiving 400 mg b.i.d., 17% receiving 600 mg b.i.d., and 50% receiving 800 mg q.d.) and 77% with FN (74% receiving 400 mg b.i.d., 78% receiving 600 mg b.i.d., and 81% receiving 800 mg q.d.). Posaconazole is well tolerated and absorbed. Divided doses of 800 mg (400 mg b.i.d.) provide the greatest posaconazole exposure.

Validation of a flow cytometric acridine orange micronuclei methodology in rats

Our laboratory has previously reported a flow cytometric acridine orange method for detection of micronucleus (MN) in the rat using cyclophosphamide as a test compound. To replace the manual method of scoring and satisfy Good Laboratory Practice (GLP) requirements, an extensive validation of the flow method was required. Therefore, manual scoring and flow cytometric determination of MN were compared using vincristine, chlorambucil, methotrexate, and doxorubicin compounds known to induce MN formation with various mechanisms of action. 1,2-Dimethylhydrazine (1,2-DH), a compound with negative or equivocal MN findings also was evaluated. The flow method consistently demonstrated dose- and time-dependent responses for MN production at all concentrations of vincristine, methotrexate, clorambucil, and doxorubicin. In contrast, manual scoring of slides failed to detect an increase in MN at the lowest doses of doxorubicin (1mg/kg) at 24 or 48 h, and methotrexate at 48 h, or any dose of methotrexate (50, 100, or 250 mg/kg) at 24h. Additionally, a dose-response for methotrexate at 48 h, and chlorambucil at 24 h were missed using manual scoring. For 1,2-DH, the flow method showed a low level (< 1.4-fold) increase in MN at all doses and times. In contrast, the manual method showed five-seven-fold increases at 24 h, but a < two-fold increase at 48 h in the highest dose only. These data may suggest that the flow method has a greater sensitivity and possibly accuracy than manual scoring. Significant decreases in polychromatic erythrocytes (PCE) were seen using both methods at approximately the same dose for all compounds. However, absolute flow cytometric PCE values were consistently higher than manual. Additional cytotoxicity parameters obtained by the flow method allowed a more complete assessment of cytotoxicity than PCE alone. Furthermore, data reported here combined with improved throughput, shortened data turnaround and reporting times, and possibly better precision due to evaluation of much larger numbers of cells clearly demonstrate the usefulness of flow cytometry method in the routine micronucleus evaluation.

Nodular invasive tracheobronchitis due to Aspergillus in a patient with systemic lupus erythematosus

Nodular or pseudomembranous tracheobronchitis due to infection by Aspergillus species is an uncommon presentation of invasive aspergillosis. Most cases have been described in severely immunocompromised hosts. We describe the case of a 23-year-old woman, with recently diagnosed systemic lupus erythematosus, who developed worsening respiratory function. Bronchoscopy revealed rapid development and progression of multiple nodular plaques in her trachea and bronchi. Endobronchial biopsy demonstrated invasive fungal infection with tissue necrosis and the presence of hyphal elements consistent with aspergillosis. To the best of our knowledge, this is only the second report of fulminant invasive tracheobronchitis due to Aspergillus in a patient with an autoimmune disease.

Adult atretic parietal cephalocele

Atretic parietal cephalocele is a congenital anomaly of childhood with poor prognostic value. The authors report an adult with associated brain malformations (interhemispheric cyst, partial corpus callosum agenesis) - but, interestingly, without any clinical symptoms related to the entity.

Isolated splenic metastasis from carcinoma of the breast

A case of isolated splenic metastasis from carcinoma of the breast in a 54 year old woman, two years after treatment for breast carcinoma, is presented. There was no involvement of other organs like liver, bone, lungs, etc. The patient underwent splenectomy and recovered without any complications. This case is being reported because of the rarity of the lesion.

Pharmaceutical development and manufacturing of a parenteral formulation of a novel antitumor agent, VNP40101M

The objective of this study was to develop and manufacture a stable parenteral formulation for Phase I clinical trials of VNP40101M (1,2-Bis(methylsulfonyl)-1-(2-chloroethyl)-2-[(2-methylamino)carbonyl] hydrazine), a novel antitumor agent. The solubility and stability of the drug was determined. Solubility studies suggested that VNP40101M exhibited poor aqueous solubility but showed appreciable solubility in nonaqueous solvents. The aqueous solubility of the drug could not be increased by adjusting the pH. At a pH above 7, base-catalyzed decomposition of VNP40101M occurred. The low octanol-water partition coefficient of 0.75 suggested poor solubility in lipophilic solvents. Based on these preformulation observations, a parenteral formulation containing 10 mg/mL of VNP40101M was prepared in a solvent system consisting of 30% ethyl alcohol and 70% polyethylene glycol-300 (PEG-300). To minimize base-catalyzed hydrolytic degradation, citric acid at 0.6% concentration was included to acidify the formulation. Rubber closures, filter membranes, and liquid transfer tubing were selected on the basis of compatibility studies and absence of loss of drug due to adsorption of these components. The formulation was subjected to accelerated stability studies and dilution studies with large volume parenteral (LVP) solutions, normal saline, and 5% dextrose injection (D5W). The results of the dilution study indicated that the formulation could be diluted in these solutions up to 2 mg/mL for 8 hours without drug precipitation and degradation. Accelerated stability studies suggested that the product should be kept at 2 degrees C to 8 degrees C for long-term storage. The developed formulation was successfully scaled up and manufactured for use in clinical trials.

Tethered-bilayer lipid membranes as a support for membrane-active peptides

An immunosensing device, comprising a lipid membrane incorporating ion channels tethered to the surface of a gold electrode, has been reported [Cornell, Braach-Maksvytis, King, Osman, Raguse, Wieczorek and Pace (1997) Nature (London) 387, 580-583]. The present article describes key steps in the assembly of the device and provides further evidence for its proposed sensing mechanism.

Permeability of lipophilic compounds in drug discovery using in-vitro human absorption model, Caco-2

Highly lipophilic compounds are often encountered in the early stages of drug discovery. The apparent permeability (Papp) of these compounds in Caco-2 cell could be underestimated because of considerable retention by the Caco-2 monolayer and non-specific binding to transwell surface. We have utilized a general approach for the determination of permeability of these compounds, which includes the addition of 1-5% DMSO in the apical (AP) and 4% bovine serum albumin (BSA) in the basolateral (BA) side. Two highly lipophilic and highly protein bound Schering compounds, SCH-A and SCH-B, exhibited poor recovery and low Papp in the conventional Caco-2 system that included 1% DMSO in the AP and BA sides. In contrast, both compounds were well absorbed in cynomolgus monkeys. Inclusion of BSA (up to 4%) in the BA side provided necessary absorptive driving force similar to in vivo sink conditions improving both recovery and Papp of these compounds as well as progesterone, a model highly lipophilic and highly protein bound compound. Whereas, the recovery and Papp of mannitol (high recovery, low permeability) and propranolol (high recovery, high permeability) remained unaffected. The presence of 4% BSA increased Papp of SCH-A, SCH-B, and progesterone by five-, four-, and three-fold, respectively. We also compared this approach with a second, based on the disappearance of the compound from the AP side, which resulted in a reasonable estimate of the permeability (23.3x10(-6) cm/s) for SCH-A. The results demonstrated that the reliable estimates of permeability of highly lipophilic compounds that are subjected to considerable retention by the cell monolayer and exhibit non-specific binding are obtained by the addition of BSA to the BA side.

A population pharmacokinetic model that describes multiple peaks due to enterohepatic recirculation of ezetimibe

BACKGROUND

Ezetimibe, a selective inhibitor of intestinal cholesterol absorption, is in clinical development for the treatment of hypercholesterolemia. It is rapidly absorbed and glucuronidated in the intestine. The parent compound and its conjugated metabolite undergo enterohepatic recirculation, resulting in multiple peaks in the plasma concentration-time profile.

OBJECTIVE

The purpose of this study was to develop a population pharmacokinetic (PPK) model for ezetimibe that incorporates enterohepatic recirculation.

METHODS

A population compartment model incorporating input from the gallbladder, consistent with food intake, was developed to account for enterohepatic recirculation. The amount recycled was allowed to vary within a subject and between subjects, accommodating variability in bile secretion. The data used consisted of 90 profiles from healthy subjects who received single or multiple doses of ezetimibe 10 or 20 mg. Modeling was carried out using a nonlinear mixed-effect function in the S-PLUS statistical program.

RESULTS

The amount of ezetimibe recycled into the central compartment was estimated to be approximately 17% to 20% of the total amount absorbed, independent of the volume of distribution. The intersubject coefficient of variation was 46% to 80% in the absorption rate constant, 27% in the distribution phase, and approximately 50% in the volume of distribution.

CONCLUSIONS

PPK models adapted for enterohepatic recirculation allowed a formal assessment of the magnitude and frequency of the enterohepatic recirculation process, and the associated intersubject and intrasubject variability in healthy subjects. The PPK approach also helped to assess the correlation between the observed maximum or minimum (24 hours postdose) concentration with the model-based area under the curve, confirming the appropriateness of the former measures as a surrogate of drug exposure for a possible correlation with pharmacodynamics.

In vitro uptake of SCH 27899 (evernimicin) by rat alveolar macrophages

The in vitro uptake of [(14)C]evernimicin ([(14)C]SCH 27899) by primary cultures of rat alveolar macrophages and hepatocytes was determined. Both cell populations exhibited linear rates of uptake. However, the initial rate of drug uptake by alveolar macrophages was about threefold higher than that by hepatocytes. These findings demonstrate that [(14)C]evernimicin is taken up by rat alveolar macrophages, supporting the likelihood that the drug is able to reach sites of infection.

PG490-88, a derivative of triptolide, blocks bleomycin-induced lung fibrosis

In this study we evaluate the antifibrotic properties of PG-490-88, a water-soluble derivative of triptolide. Triptolide is an oxygenated diterpene that is derived from a traditional Chinese herb that has potent immunosuppressive and antitumor activity. We used the intratracheal bleomycin mouse model and found that PG490-88 inhibits fibrosis in the bleomycin group when given the same day or 5 days after bleomycin. PG490-88 also markedly reduced the number of myofibroblasts in the bleomycin treatment group. An enzyme-linked immunosorbent assay of transforming growth factor (TGF)-beta in the bronchoalveolar lavage fluid showed a significant decrease in TGF-beta in the PG490-88-treated groups compared to the bleomycin-treated group. Additionally, triptolide blocked bleomycin-induced increase in TGF-beta mRNA in cultured normal human lung fibroblasts. The efficacy of PG490-88 when administered late after bleomycin installation suggests a potential role in the treatment of idiopathic pulmonary fibrosis.

Practical aspects of mutagenicity testing strategy: an industrial perspective

Genetic toxicology studies play a central role in the development and marketing of new chemicals for pharmaceutical, agricultural, industrial, and consumer use. During the discovery phase of product development, rapid screening tests that require minimal amounts of test materials are used to assist in the design and prioritization of new molecules. At this stage, a modified Salmonella reverse mutation assay and an in vitro micronucleus test with mammalian cell culture are frequently used for screening. Regulatory genetic toxicology studies are conducted with a short list of compounds using protocols that conform to various international guidelines. A set of four assays usually constitutes the minimum test battery that satisfies global requirements. This set includes a bacterial reverse mutation assay, an in vitro cytogenetic test with mammalian cell culture, an in vitro gene mutation assay in mammalian cell cultures, and an in vivo rodent bone marrow micronucleus test. Supplementary studies are conducted in certain instances either as a follow-up to the findings from this initial testing battery and/or to satisfy a regulatory requirement. Currently available genetic toxicology assays have helped the scientific and industrial community over the past several decades in evaluating the mutagenic potential of chemical agents. The emerging field of toxicogenomics has the potential to redefine our ability to study the response of cells to genetic damage and hence our ability to study threshold phenomenon.

In vivo rodent micronucleus assay: protocol, conduct and data interpretation

In vivo rodent micronucleus assay has been widely used to detect genotoxicity. Evaluation of micronucleus induction is the primary in vivo test in a battery of genotoxicity tests and is recommended by the regulatory agencies around the globe to be conducted as part of product safety assessment. The assay, when performed appropriately, detects both clastogenicity and aneugenicity. Methods for performing micronucleus evaluation have evolved since its initial description in the 1970s. In recent years, the focus has been directed toward improving micronucleus detection with high efficiency by proposing data-based recommendations to the standard initial protocol design. Such improvements include, e.g., the use of appropriate harvest time(s), inclusion of one or both sexes, number of doses tested, limit dose, integrating micronucleus assessment into the routine toxicology studies, use of fluorescent staining, automation of micronucleus detection and assessment of micronuclei in multiple tissues. This protocol paper describes: the mechanism of micronucleus formation, a generalized protocol for manual detection, enumeration of micronuclei, and data interpretation in light of published information thus far, on the regulatory aspects of this assay. Certain recent protocol issues that are practical in nature are equally valid in relation to standard manual method and provide robust database, which are also included for consideration. It is expected that such improvements of the protocol will continue to drive the utility of this assay in the product safety assessment.