BackgroundDecreased brain insulin levels exacerbate cognitive decline in AD. Insulin in the brain... more BackgroundDecreased brain insulin levels exacerbate cognitive decline in AD. Insulin in the brain is derived from systemic circulation via the blood‐brain barrier (BBB). We hypothesize that type II diabetes (T2D) sequelae and Aβ peptide exposure disrupt insulin signaling at the BBB and inhibit insulin delivery to brain. Further, we propose insulin signaling defects at the BBB contribute to Aβ accumulation in AD brain.MethodsThe following studies were performed in wild‐type (WT) mice on regular chow (RC) diet, WT mice on high fat (HF) diet (manifest insulin resistance), APP/PS1 transgenic mice on RC diet (overexpress Aβ), and APP/PS1 mice on HF diet (overexpress Aβ + insulin resistance). After femoral injection of 125I‐insulin or 125I‐Aβ42, the brain accumulation was monitored between 0‐40 min by dynamic SPECT/CT imaging. The brain influx clearance was estimated by the slope obtained from Gjedde‐Patlak graphical analysis. Cerebral microvessels were harvested, and reverse phase protei...
Journal of Pharmaceutical and Biomedical Analysis, 2019
HighlightsA bioanalytical method for accurate and precise quantification of scopolamine in human ... more HighlightsA bioanalytical method for accurate and precise quantification of scopolamine in human serum was developed and validated.This solid‐phase extraction and liquid chromatography – mass spectrometry based assay requires only 0.5 mL of serum.It can quantify a broad range of concentration between 5–5000 pg/mL. Lower limit of quantification was 5 pg/mL.The total assay precision and accuracy was 6.3% and 96%, respectively.The assay was applied in clinical studies to measure scopolamine in serum after administering it as IV bolus and TDS. Abstract Scopolamine is an anticholinergic alkaloid that is widely used in the form of a transdermal system to manage nausea associated with motion sickness. Currently available methods to quantify scopolamine require large sample volumes and involve cumbersome sample preparation. In this work, a simple method for the rapid separation and sensitive quantification of scopolamine in human serum was developed. Scopolamine was extracted from 0.5 mL of human serum using solid‐phase extraction. The extracted samples were injected onto Zorbax XDB‐C18 column (4.6 × 50 mm, 1.8 &mgr;m, and 600 bar) on an Agilent 1200 series HPLC. The chromatographic separation involved gradient elution with water and acetonitrile containing 0.1% v/v formic acid as a mobile phase. The samples were quantified in positive ion mode using a TSQ Quantum triple quadrupole mass spectrometer. The assay was validated and found to be linear over a concentration range of 5–5000 pg/mL. The total assay precision and accuracy was 6.3% and 96%, respectively. The lower limit of quantification (LLOQ) of the assay was 5 pg/mL. The assay was used in a human pharmacokinetic study to measure the concentration of scopolamine in serum after an administering scopolamine as transdermal delivery system or as an intravenous bolus dose.
Targeting therapeutic or diagnostic proteins to the nervous system is limited by the presence of ... more Targeting therapeutic or diagnostic proteins to the nervous system is limited by the presence of the blood–brain barrier. We report that a F(ab′)2 fragment of a monoclonal antibody against fibrillar human Aβ42 that is polyamine (p)‐modified has increased permeability at the blood–brain barrier, comparable binding to the antigen, and comparable in vitro binding to amyloid plaques in Alzheimer’s disease (AD) transgenic mouse brain sections. Intravenous injection of the pF(ab′)24.1 in the AD transgenic mouse demonstrated efficient targeting to amyloid plaques throughout the brain, whereas the unmodified fragment did not. Removal of the Fc portion of this antibody derivative will minimize the inflammatory response and cerebral hemorrhaging associated with passive immunization and provide increased therapeutic potential for treating AD. Coupling contrast agents/radioisotopes might facilitate the molecular imaging of amyloid plaques with magnetic resonance imaging/positron emission tomogr...
Background: Age is the most common risk factor for Alzheimer’s disease (AD), a neurodegenerative ... more Background: Age is the most common risk factor for Alzheimer’s disease (AD), a neurodegenerative disorder characterized by the hallmarks of toxic amyloid-β (Aβ) plaques and hyperphosphorylated tau tangles. Moreover, sub-physiological brain insulin levels have emerged as a pathological manifestation of AD. Objective: Identify age-related changes in the plasma disposition and blood-brain barrier (BBB) trafficking of Aβ peptides and insulin in mice. Methods: Upon systemic injection of 125I-Aβ40, 125I-Aβ42, or 125I-insulin, the plasma pharmacokinetics and brain influx were assessed in wild-type (WT) or AD transgenic (APP/PS1) mice at various ages. Additionally, publicly available single-cell RNA-Seq data [GSE129788] was employed to investigate pathways regulating BBB transport in WT mice at different ages. Results: The brain influx of 125I-Aβ40, estimated as the permeability-surface area product, decreased with age, accompanied by an increase in plasma AUC. In contrast, the brain influx...
Dense nanolipid fluid (DNLF) dispersions are highly concentrated aqueous dispersions of lipid nan... more Dense nanolipid fluid (DNLF) dispersions are highly concentrated aqueous dispersions of lipid nanocarriers (LNCs) with more than 1015 lipid particles per cubic centimeter. Descriptions of dense nanolipid fluid dispersions in the scientific literature are rare, and they have not been used to encapsulate drugs. In this paper we describe the synthesis of DNLF dispersions comprising ibuprofen using a recently described twin-screw extrusion process. We report that such dispersions are stable, bind ibuprofen tightly and yet provide high transdermal drug permeation. Ibuprofen DNLF dispersions prepared according to the present study provide up to five times greater flux of the pharmacologically active S-ibuprofen isomer through human skin than a commercially available racemic ibuprofen emulsion product. We demonstrate scaling up the twin-screw extrusion method to pilot production for a stable, highly permeating ibuprofen DNLF composition based on excipients approved by the US FDA for use in topical products as a key step towards development of a commercially viable, FDA approvable topical ibuprofen medicine to treat osteoarthritis, which has never before been accomplished.
Journal of Cerebral Blood Flow & Metabolism, 2017
Impaired brain clearance of amyloid-beta peptides (Aβ) 40 and 42 across the blood–brain barrier (... more Impaired brain clearance of amyloid-beta peptides (Aβ) 40 and 42 across the blood–brain barrier (BBB) is believed to be one of the pathways responsible for Alzheimer’s disease (AD) pathogenesis. Hyperinsulinemia prevalent in type II diabetes was shown to damage cerebral vasculature and increase Aβ accumulation in AD brain. However, there is no clarity on how aberrations in peripheral insulin levels affect Aβ accumulation in the brain. This study describes, for the first time, an intricate relation between plasma insulin and Aβ transport at the BBB. Upon peripheral insulin administration in wild-type mice: the plasma clearance of Aβ40 increased, but Aβ42 clearance reduced; the plasma-to-brain influx of Aβ40 increased, and that of Aβ42 reduced; and the clearance of intracerebrally injected Aβ40 decreased, whereas Aβ42 clearance increased. In hCMEC/D3 monolayers (in vitro BBB model) exposed to insulin, the luminal uptake and luminal-to-abluminal permeability of Aβ40 increased and that ...
BackgroundDecreased brain insulin levels exacerbate cognitive decline in AD. Insulin in the brain... more BackgroundDecreased brain insulin levels exacerbate cognitive decline in AD. Insulin in the brain is derived from systemic circulation via the blood‐brain barrier (BBB). We hypothesize that type II diabetes (T2D) sequelae and Aβ peptide exposure disrupt insulin signaling at the BBB and inhibit insulin delivery to brain. Further, we propose insulin signaling defects at the BBB contribute to Aβ accumulation in AD brain.MethodsThe following studies were performed in wild‐type (WT) mice on regular chow (RC) diet, WT mice on high fat (HF) diet (manifest insulin resistance), APP/PS1 transgenic mice on RC diet (overexpress Aβ), and APP/PS1 mice on HF diet (overexpress Aβ + insulin resistance). After femoral injection of 125I‐insulin or 125I‐Aβ42, the brain accumulation was monitored between 0‐40 min by dynamic SPECT/CT imaging. The brain influx clearance was estimated by the slope obtained from Gjedde‐Patlak graphical analysis. Cerebral microvessels were harvested, and reverse phase protei...
Journal of Pharmaceutical and Biomedical Analysis, 2019
HighlightsA bioanalytical method for accurate and precise quantification of scopolamine in human ... more HighlightsA bioanalytical method for accurate and precise quantification of scopolamine in human serum was developed and validated.This solid‐phase extraction and liquid chromatography – mass spectrometry based assay requires only 0.5 mL of serum.It can quantify a broad range of concentration between 5–5000 pg/mL. Lower limit of quantification was 5 pg/mL.The total assay precision and accuracy was 6.3% and 96%, respectively.The assay was applied in clinical studies to measure scopolamine in serum after administering it as IV bolus and TDS. Abstract Scopolamine is an anticholinergic alkaloid that is widely used in the form of a transdermal system to manage nausea associated with motion sickness. Currently available methods to quantify scopolamine require large sample volumes and involve cumbersome sample preparation. In this work, a simple method for the rapid separation and sensitive quantification of scopolamine in human serum was developed. Scopolamine was extracted from 0.5 mL of human serum using solid‐phase extraction. The extracted samples were injected onto Zorbax XDB‐C18 column (4.6 × 50 mm, 1.8 &mgr;m, and 600 bar) on an Agilent 1200 series HPLC. The chromatographic separation involved gradient elution with water and acetonitrile containing 0.1% v/v formic acid as a mobile phase. The samples were quantified in positive ion mode using a TSQ Quantum triple quadrupole mass spectrometer. The assay was validated and found to be linear over a concentration range of 5–5000 pg/mL. The total assay precision and accuracy was 6.3% and 96%, respectively. The lower limit of quantification (LLOQ) of the assay was 5 pg/mL. The assay was used in a human pharmacokinetic study to measure the concentration of scopolamine in serum after an administering scopolamine as transdermal delivery system or as an intravenous bolus dose.
Targeting therapeutic or diagnostic proteins to the nervous system is limited by the presence of ... more Targeting therapeutic or diagnostic proteins to the nervous system is limited by the presence of the blood–brain barrier. We report that a F(ab′)2 fragment of a monoclonal antibody against fibrillar human Aβ42 that is polyamine (p)‐modified has increased permeability at the blood–brain barrier, comparable binding to the antigen, and comparable in vitro binding to amyloid plaques in Alzheimer’s disease (AD) transgenic mouse brain sections. Intravenous injection of the pF(ab′)24.1 in the AD transgenic mouse demonstrated efficient targeting to amyloid plaques throughout the brain, whereas the unmodified fragment did not. Removal of the Fc portion of this antibody derivative will minimize the inflammatory response and cerebral hemorrhaging associated with passive immunization and provide increased therapeutic potential for treating AD. Coupling contrast agents/radioisotopes might facilitate the molecular imaging of amyloid plaques with magnetic resonance imaging/positron emission tomogr...
Background: Age is the most common risk factor for Alzheimer’s disease (AD), a neurodegenerative ... more Background: Age is the most common risk factor for Alzheimer’s disease (AD), a neurodegenerative disorder characterized by the hallmarks of toxic amyloid-β (Aβ) plaques and hyperphosphorylated tau tangles. Moreover, sub-physiological brain insulin levels have emerged as a pathological manifestation of AD. Objective: Identify age-related changes in the plasma disposition and blood-brain barrier (BBB) trafficking of Aβ peptides and insulin in mice. Methods: Upon systemic injection of 125I-Aβ40, 125I-Aβ42, or 125I-insulin, the plasma pharmacokinetics and brain influx were assessed in wild-type (WT) or AD transgenic (APP/PS1) mice at various ages. Additionally, publicly available single-cell RNA-Seq data [GSE129788] was employed to investigate pathways regulating BBB transport in WT mice at different ages. Results: The brain influx of 125I-Aβ40, estimated as the permeability-surface area product, decreased with age, accompanied by an increase in plasma AUC. In contrast, the brain influx...
Dense nanolipid fluid (DNLF) dispersions are highly concentrated aqueous dispersions of lipid nan... more Dense nanolipid fluid (DNLF) dispersions are highly concentrated aqueous dispersions of lipid nanocarriers (LNCs) with more than 1015 lipid particles per cubic centimeter. Descriptions of dense nanolipid fluid dispersions in the scientific literature are rare, and they have not been used to encapsulate drugs. In this paper we describe the synthesis of DNLF dispersions comprising ibuprofen using a recently described twin-screw extrusion process. We report that such dispersions are stable, bind ibuprofen tightly and yet provide high transdermal drug permeation. Ibuprofen DNLF dispersions prepared according to the present study provide up to five times greater flux of the pharmacologically active S-ibuprofen isomer through human skin than a commercially available racemic ibuprofen emulsion product. We demonstrate scaling up the twin-screw extrusion method to pilot production for a stable, highly permeating ibuprofen DNLF composition based on excipients approved by the US FDA for use in topical products as a key step towards development of a commercially viable, FDA approvable topical ibuprofen medicine to treat osteoarthritis, which has never before been accomplished.
Journal of Cerebral Blood Flow & Metabolism, 2017
Impaired brain clearance of amyloid-beta peptides (Aβ) 40 and 42 across the blood–brain barrier (... more Impaired brain clearance of amyloid-beta peptides (Aβ) 40 and 42 across the blood–brain barrier (BBB) is believed to be one of the pathways responsible for Alzheimer’s disease (AD) pathogenesis. Hyperinsulinemia prevalent in type II diabetes was shown to damage cerebral vasculature and increase Aβ accumulation in AD brain. However, there is no clarity on how aberrations in peripheral insulin levels affect Aβ accumulation in the brain. This study describes, for the first time, an intricate relation between plasma insulin and Aβ transport at the BBB. Upon peripheral insulin administration in wild-type mice: the plasma clearance of Aβ40 increased, but Aβ42 clearance reduced; the plasma-to-brain influx of Aβ40 increased, and that of Aβ42 reduced; and the clearance of intracerebrally injected Aβ40 decreased, whereas Aβ42 clearance increased. In hCMEC/D3 monolayers (in vitro BBB model) exposed to insulin, the luminal uptake and luminal-to-abluminal permeability of Aβ40 increased and that ...
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Papers by Karunya Kandimalla