Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 19 de 19
Filter
1.
J Am Heart Assoc ; 13(4): e031749, 2024 Feb 20.
Article in English | MEDLINE | ID: mdl-38348800

ABSTRACT

BACKGROUND: Asymptomatic intracerebral hemorrhage (aICH) occurs in approximately 35% of patients with acute ischemic stroke after endovascular thrombectomy. Unlike symptomatic ICH, studies evaluating the effect of aICH on outcomes have been inconclusive. We performed a systematic review and meta-analysis to evaluate the long-term effects of postendovascular thrombectomy aICH. METHODS AND RESULTS: The meta-analysis protocol was submitted to the International Prospective Register of Systematic Reviews a priori. PubMed, Scopus, and Web of Science were searched from inception through September 2023, yielding 312 studies. Two authors independently reviewed all abstracts. Included studies contained adult patients with ischemic stroke undergoing endovascular thrombectomy with follow-up imaging assessment of ICH reporting comparative outcomes according to aICH versus no ICH. After screening, 60 papers were fully reviewed, and 10 studies fulfilled inclusion criteria (n=5723 patients total, 1932 with aICH). Meta-analysis was performed using Cochrane RevMan v5.4. Effects were estimated by a random-effects model to estimate summary odds ratio (OR) of the effect of aICH versus no ICH on primary outcomes of 90-day modified Rankin Scale 3 to 6 and mortality. The presence of aICH was associated with a higher odds of 90-day mRS 3 to 6 (OR, 2.17 [95% CI, 1.81-2.60], P<0.0001, I2 46% Q 19.15) and mortality (OR, 1.72 [95% CI, 1.17-2.53], P:0.005, I2 79% Q 27.59) compared with no ICH. This difference was maintained following subgroup analysis according to hemorrhage classification and recanalization status. CONCLUSIONS: The presence of aICH is associated with worse 90-day functional outcomes and higher mortality. Further studies to evaluate the factors predicting aICH and treatments aimed at reducing its occurrence are warranted.


Subject(s)
Brain Ischemia , Endovascular Procedures , Ischemic Stroke , Stroke , Adult , Humans , Stroke/diagnosis , Brain Ischemia/diagnosis , Treatment Outcome , Cerebral Hemorrhage/diagnostic imaging , Cerebral Hemorrhage/therapy , Thrombectomy/methods , Endovascular Procedures/methods
2.
J Trauma Acute Care Surg ; 93(4): 427-438, 2022 10 01.
Article in English | MEDLINE | ID: mdl-35797620

ABSTRACT

INTRODUCTION: The pathophysiology of the inflammatory response after major trauma is complex, and the magnitude correlates with severity of tissue injury and outcomes. Study of infection-mediated immune pathways has demonstrated that cellular microRNAs may modulate the inflammatory response. The authors hypothesize that the expression of microRNAs would correlate to complicated recoveries in polytrauma patients (PtPs). METHODS: Polytrauma patients enrolled in the prospective observational Tissue and Data Acquisition Protocol with Injury Severity Score of >15 were selected for this study. Polytrauma patients were divided into complicated recoveries and uncomplicated recovery groups. Polytrauma patients' blood samples were obtained at the time of admission (T0). Established biomarkers of systemic inflammation, including cytokines and chemokines, were measured using multiplexed Luminex-based methods, and novel microRNAs were measured in plasma samples using multiplex RNA hybridization. RESULTS: Polytrauma patients (n = 180) had high Injury Severity Score (26 [20-34]) and complicated recovery rate of 33%. MicroRNAs were lower in PtPs at T0 compared with healthy controls, and bivariate analysis demonstrated that variations of microRNAs correlated with age, race, comorbidities, venous thromboembolism, pulmonary complications, complicated recovery, and mortality. Positive correlations were noted between microRNAs and interleukin 10, vascular endothelial growth factor, Acute Physiology and Chronic Health Evaluation, and Sequential Organ Failure Assessment scores. Multivariable Lasso regression analysis of predictors of complicated recovery based on microRNAs, cytokines, and chemokines revealed that miR-21-3p and monocyte chemoattractant protein-1 were predictive of complicated recovery with an area under the curve of 0.78. CONCLUSION: Systemic microRNAs were associated with poor outcomes in PtPs, and results are consistent with previously described trends in critically ill patients. These early biomarkers of inflammation might provide predictive utility in early complicated recovery diagnosis and prognosis. Because of their potential to regulate immune responses, microRNAs may provide therapeutic targets for immunomodulation. LEVEL OF EVIDENCE: Diagnostic Tests/Criteria; Level II.


Subject(s)
Convalescence , MicroRNAs , Multiple Trauma , Severity of Illness Index , Biomarkers/metabolism , Chemokine CCL2/metabolism , Humans , Inflammation/diagnosis , Interleukin-10/metabolism , MicroRNAs/metabolism , Multiple Trauma/complications , Multiple Trauma/diagnosis , Vascular Endothelial Growth Factor A/metabolism
3.
Crit Care Med ; 50(2): 296-306, 2022 02 01.
Article in English | MEDLINE | ID: mdl-34259445

ABSTRACT

OBJECTIVES: To evaluate early activation of latent viruses in polytrauma patients and consider prognostic value of viral micro-RNAs in these patients. DESIGN: This was a subset analysis from a prospectively collected multicenter trauma database. Blood samples were obtained upon admission to the trauma bay (T0), and trauma metrics and recovery data were collected. SETTING: Two civilian Level 1 Trauma Centers and one Military Treatment Facility. PATIENTS: Adult polytrauma patients with Injury Severity Scores greater than or equal to 16 and available T0 plasma samples were included in this study. Patients with ICU admission greater than 14 days, mechanical ventilation greater than 7 days, or mortality within 28 days were considered to have a complicated recovery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Polytrauma patients (n = 180) were identified, and complicated recovery was noted in 33%. Plasma samples from T0 underwent reverse transcriptase-quantitative polymerase chain reaction analysis for Kaposi's sarcoma-associated herpesvirus micro-RNAs (miR-K12_10b and miRK-12-12) and Epstein-Barr virus-associated micro-RNA (miR-BHRF-1), as well as Luminex multiplex array analysis for established mediators of inflammation. Ninety-eight percent of polytrauma patients were found to have detectable Kaposi's sarcoma-associated herpesvirus and Epstein-Barr virus micro-RNAs at T0, whereas healthy controls demonstrated 0% and 100% detection rate for Kaposi's sarcoma-associated herpesvirus and Epstein-Barr virus, respectively. Univariate analysis revealed associations between viral micro-RNAs and polytrauma patients' age, race, and postinjury complications. Multivariate least absolute shrinkage and selection operator analysis of clinical variables and systemic biomarkers at T0 revealed that interleukin-10 was the strongest predictor of all viral micro-RNAs. Multivariate least absolute shrinkage and selection operator analysis of systemic biomarkers as predictors of complicated recovery at T0 demonstrated that miR-BHRF-1, miR-K12-12, monocyte chemoattractant protein-1, and hepatocyte growth factor were independent predictors of complicated recovery with a model complicated recovery prediction area under the curve of 0.81. CONCLUSIONS: Viral micro-RNAs were detected within hours of injury and correlated with poor outcomes in polytrauma patients. Our findings suggest that transcription of viral micro-RNAs occurs early in the response to trauma and may be associated with the biological processes involved in polytrauma-induced complicated recovery.


Subject(s)
MicroRNAs/analysis , Multiple Trauma/immunology , Multiple Trauma/virology , RNA, Viral/analysis , Adult , Female , Herpesvirus 4, Human/genetics , Herpesvirus 4, Human/isolation & purification , Herpesvirus 8, Human/genetics , Herpesvirus 8, Human/isolation & purification , Humans , Male , MicroRNAs/blood , MicroRNAs/genetics , Middle Aged , RNA, Viral/blood , RNA, Viral/genetics , Reverse Transcriptase Polymerase Chain Reaction/methods , Reverse Transcriptase Polymerase Chain Reaction/statistics & numerical data
4.
Surgery ; 168(4): 662-670, 2020 10.
Article in English | MEDLINE | ID: mdl-32600883

ABSTRACT

BACKGROUND: Post-traumatic acute kidney injury has occurred in every major military conflict since its initial description during World War II. To ensure the proper treatment of combat casualties, early detection is critical. This study therefore aimed to investigate combat-related post-traumatic acute kidney injury in recent military conflicts, used machine learning algorithms to identify clinical and biomarker variables associated with the development of post-traumatic acute kidney injury, and evaluated the effects of post-traumatic acute kidney injury on wound healing and nosocomial infection. METHODS: We conducted a retrospective clinical cohort review of 73 critically injured US military service members who sustained major combat-related extremity wounds and had collected injury characteristics, assayed serum and tissue biopsy samples for the expression of protein and messenger ribonucleic acid biomarkers. Bivariate analyses and random forest recursive feature elimination classification algorithms were used to identify associated injury characteristics and biomarker variables. RESULTS: The incidence of post-traumatic acute kidney injury was 20.5%. Of that, 86% recovered baseline renal function and only 2 (15%) of the acute kidney injury group required renal replacement therapy. Random forest recursive feature elimination algorithms were able to estimate post-traumatic acute kidney injury with the area under the curve of 0.93, sensitivity of 0.91, and specificity of 0.91. Post-traumatic acute kidney injury was associated with injury severity score, serum epidermal growth factor, and tissue activin A type receptor 1, matrix metallopeptidase 10, and X-C motif chemokine ligand 1 expression. Patients with post-traumatic acute kidney injury exhibited poor wound healing and increased incidence of nosocomial infections. CONCLUSION: The occurrence of acute kidney injury in combat casualties may be estimated using injury characteristics and serum and tissue biomarkers. External validations of these models are necessary to generalize for all trauma patients.


Subject(s)
Acute Kidney Injury/diagnosis , Cytokines/blood , Inflammation/blood , War-Related Injuries/complications , Acute Kidney Injury/blood , Acute Kidney Injury/epidemiology , Acute Kidney Injury/etiology , Adult , Afghan Campaign 2001- , Algorithms , Biomarkers/blood , Cross Infection/complications , Early Diagnosis , Female , Humans , Incidence , Injury Severity Score , Iraq War, 2003-2011 , Machine Learning , Male , Military Personnel , Retrospective Studies , Risk Factors , Wound Healing , Young Adult
5.
World J Surg ; 44(7): 2263, 2020 07.
Article in English | MEDLINE | ID: mdl-32306080

ABSTRACT

In the original article, the units indicated on the y-axes of Fig. 3 are incorrectly labelled. The correct label is pg/mL. Following is the corrected Fig. 3.

6.
J Trauma Acute Care Surg ; 88(3): 379-389, 2020 03.
Article in English | MEDLINE | ID: mdl-32107353

ABSTRACT

BACKGROUND: The timing of coverage of an open wound is based on heavily on clinical gestalt. DoD's Surgical Critical Care Initiative created a clinical decision support tool that predicts wound closure success using clinical and biomarker data. The military uses a regimented protocol consisting of serial washouts and debridements. While decisions around wound closure in civilian centers are subject to the same clinical parameters, preclosure wound management is, generally, much more variable. We hypothesized that the variability in management would affect local biomarker expression within these patients. METHODS: We compared data from 116 wounds in 73 military patients (MP) to similar data from 88 wounds in 78 civilian patients (CP). We used Wilcoxon rank-sum tests to assess concentrations of 32 individual biomarkers taken from wound effluent. Along with differences in the debridement frequency, we focused on these local biomarkers in MP and CP at both the first washout and the washout performed just prior to attempted closure. RESULTS: On average, CP waited longer from the time of injury to closure (21.9 days, vs. 11.6 days, p < 0.0001) but had a similar number of washouts (3.86 vs. 3.44, p = 0.52). When comparing the wound effluent between the two populations, they had marked biochemical differences both when comparing the results at the first washout and at the time of closure. However, in a subset of civilian patients whose average number of days between washouts was never more than 72 hours, these differences ceased to be significant for most variables. CONCLUSION: There were significant differences in the baseline biochemical makeup of wounds in the CP and MP. These differences could be eliminated if both were treated under similar wound care paradigms. Variations in therapy affect not only outcomes but also the actual biochemical makeup of wounds. LEVEL OF EVIDENCE: Therapeutic, level IV.


Subject(s)
Biomarkers/metabolism , Clinical Decision-Making , Clinical Protocols , Soft Tissue Injuries/physiopathology , Soft Tissue Injuries/surgery , Wound Closure Techniques , Wound Healing/physiology , Adolescent , Adult , Debridement , Humans , Male , Military Personnel , Precision Medicine , Prospective Studies , Time-to-Treatment , Young Adult
7.
World J Surg ; 44(7): 2255-2262, 2020 07.
Article in English | MEDLINE | ID: mdl-31748888

ABSTRACT

BACKGROUND: Tools to assist clinicians in predicting pneumonia could lead to a significant decline in morbidity. Therefore, we sought to develop a model in combat trauma patients for identifying those at highest risk of pneumonia. METHODS: This was a retrospective study of 73 primarily blast-injured casualties with combat extremity wounds. Binary classification models for pneumonia prediction were developed with measurements of injury severity from the Abbreviated Injury Scale (AIS), transfusion blood products received before arrival at Walter Reed National Military Medical Center (WRNMMC), and serum protein levels. Predictive models were generated with leave-one-out-cross-validation using the variable selection method of backward elimination (BE) and the machine learning algorithms of random forests (RF) and logistic regression (LR). BE was attempted with two predictor sets: (1) all variables and (2) serum proteins alone. RESULTS: Incidence of pneumonia was 12% (n = 9). Different variable sets were produced by BE when considering all variables and just serum proteins alone. BE selected the variables ISS, AIS chest, and cryoprecipitate within the first 24 h following injury for the first predictor set 1 and FGF-basic, IL-2R, and IL-6 for predictor set 2. Using both variable sets, a RF was generated with AUCs of 0.95 and 0.87-both higher than LR algorithms. CONCLUSION: Advanced modeling allowed for the identification of clinical and biomarker data predictive of pneumonia in a cohort of predominantly blast-injured combat trauma patients. The generalizability of the models developed here will require an external validation dataset.


Subject(s)
Blast Injuries/complications , Clinical Decision Rules , Cross Infection/diagnosis , Military Personnel , Pneumonia/diagnosis , Adult , Algorithms , Cross Infection/epidemiology , Cross Infection/etiology , Extremities/injuries , Humans , Incidence , Logistic Models , Machine Learning , Male , Models, Statistical , Pneumonia/epidemiology , Pneumonia/etiology , Retrospective Studies , Risk Assessment , Risk Factors , Sensitivity and Specificity , United States , Young Adult
8.
J Trauma Acute Care Surg ; 87(5): 1125-1132, 2019 11.
Article in English | MEDLINE | ID: mdl-31425495

ABSTRACT

BACKGROUND: Identifying clinical and biomarker profiles of trauma patients may facilitate the creation of models that predict postoperative complications. We sought to determine the utility of modeling for predicting severe sepsis (SS) and organ space infections (OSI) following laparotomy for abdominal trauma. METHODS: Clinical and molecular biomarker data were collected prospectively from patients undergoing exploratory laparotomy for abdominal trauma at a Level I trauma center between 2014 and 2017. Machine learning algorithms were used to develop models predicting SS and OSI. Random forest (RF) was performed, and features were selected using backward elimination. The SS model was trained on 117 records and validated using the leave-one-out method on the remaining 15 records. The OSI model was trained on 113 records and validated on the remaining 19. Models were assessed using areas under the curve. RESULTS: One hundred thirty-two patients were included (median age, 30 years [23-42 years], 68.9% penetrating injury, median Injury Severity Score of 18 [10-27]). Of these, 10.6% (14 of 132) developed SS and 13.6% (18 of 132) developed OSI. The final RF model resulted in five variables for SS (Penetrating Abdominal Trauma Index, serum epidermal growth factor, monocyte chemoattractant protein-1, interleukin-6, and eotaxin) and four variables for OSI (Penetrating Abdominal Trauma Index, serum epidermal growth factor, monocyte chemoattractant protein-1, and interleukin-8). The RF models predicted SS and OSI with areas under the curve of 0.798 and 0.774, respectively. CONCLUSION: Random forests with RFE can help identify clinical and biomarker profiles predictive of SS and OSI after trauma laparotomy. Once validated, these models could be used as clinical decision support tools for earlier detection and treatment of infectious complications following injury. LEVEL OF EVIDENCE: Prognostic, level III.


Subject(s)
Abdominal Injuries/surgery , Decision Support Techniques , Models, Biological , Sepsis/epidemiology , Surgical Procedures, Operative/adverse effects , Surgical Wound Infection/epidemiology , Abdominal Injuries/diagnosis , Adult , Clinical Decision-Making , Female , Humans , Injury Severity Score , Logistic Models , Machine Learning , Male , Predictive Value of Tests , Prospective Studies , Risk Assessment/methods , Sepsis/etiology , Sepsis/prevention & control , Surgical Wound Infection/etiology , Surgical Wound Infection/prevention & control , Trauma Centers/statistics & numerical data , Young Adult
9.
Ann Surg ; 270(3): 535-543, 2019 09.
Article in English | MEDLINE | ID: mdl-31348045

ABSTRACT

BACKGROUND: Both the frequency and high complication rates associated with extremity wounds in recent military conflicts have highlighted the need for clinical decision support tools (CDST) to decrease time to wound closure and wound failure rates. METHODS: Machine learning was used to estimate both successful wound closure (based on penultimate debridement biomarker data) and the necessary number of surgical debridements (based on presentation biomarkers) in 73 service members treated according to military guidelines based on clinical data and the local/systemic level of 32 cytokines. Models were trained to estimate successful closure including an additional 8 of 80 civilian patients with similar injury patterns. Previous analysis has demonstrated the potential to reduce the number of operative debridements by 2, with resulting decreases in ICU and hospital LOS, while decreasing the rate of wound failure. RESULTS: Analysis showed similar cytokine responses when civilians followed a military-like treatment schedule with surgical debridements every 24 to 72 hours. A model estimating successful closure had AUC of 0.89. Model performance in civilians degraded when these had a debridement interval > 72 hours (73 of the 80 civilians). A separate model estimating the number of debridements required to achieve successful closure had a multiclass AUC of 0.81. CONCLUSION: CDSTs can be developed using biologically compatible civilian and military populations as cytokine response is highly influenced by surgical treatment. Our CDSTs may help identify who may require serial debridements versus early closure, and precisely when traumatic wounds should optimally be closed.


Subject(s)
Cytokines/analysis , Extremities/injuries , Precision Medicine/methods , Wound Closure Techniques , Wound Healing/physiology , Wounds and Injuries/surgery , Cohort Studies , Debridement/methods , Decision Support Techniques , Extremities/surgery , Female , Humans , Injury Severity Score , Kaplan-Meier Estimate , Male , Military Personnel/statistics & numerical data , Orthopedic Procedures/methods , Precision Medicine/mortality , Prognosis , Proportional Hazards Models , Retrospective Studies , Risk Assessment , Survival Analysis , Time Factors , Treatment Outcome , Wounds and Injuries/blood , Wounds and Injuries/diagnosis
11.
J Indian Soc Periodontol ; 21(5): 391-397, 2017.
Article in English | MEDLINE | ID: mdl-29491586

ABSTRACT

CONTEXT: Dentinal hypersensitivity (DH) is a chronic disorder in which patients report sharp and acute pain to a variety of stimuli. Till date, a standardized procedure to treat DH is missing, though several alternative treatment strategies have been designed, including laser therapies. AIM: The aim of the study was to treat DH with minimum chemical concentration and least laser energy level with longer follow-up period. MATERIALS AND METHODS: One hundred and twenty patients were randomly divided into four groups: (i) Group 1-5% potassium nitrate (KNO3); (ii) Group 2 - gallium-aluminum-arsenide diode laser (62.2 J/cm2, wavelength - 980 nm, noncontact pulse mode, and power wattage - 0.5 W); (iii) Group 3 - combined 5% KNO3 and the diode laser; and (iv) Group 4 - placebo (control). The visual analog scale (VAS) scores were recorded, analyzed, and compared to tactile stimuli, cold water, and air blast tests at different intervals for 6 weeks. RESULTS: Synergistic use of 5% KNO3 and diode laser (Group 3) significantly reduced the DH pain, which was almost negligible after 6th week (97%-99% of the pain was reported to be relieved) and showed promising results than any other studied groups. Further, the diode laser (Group 2) showed better results than 5% KNO3 (Group 1). One-way ANOVA and Bonferroni correction post hoc test revealed the combination of groups with significant differences in the mean VAS scores at the different interval of time (P < 0.01). CONCLUSIONS: Convincingly, the combined application of 5% KNO3 with the diode laser can be recommended for treating DH patients.

12.
J Neurosci ; 34(13): 4528-33, 2014 Mar 26.
Article in English | MEDLINE | ID: mdl-24671998

ABSTRACT

Handling (H) and cross-fostering (CF) rodent pups during postnatal development triggers changes in maternal behavior which in turn trigger long-term physiological changes in the offspring. However, less is known about the short-term effects of H and CF on infant development. In this study we hypothesized that manipulations of maternal care affect the onset of hearing in Wistar rats. To test this hypothesis we obtained auditory brainstem responses (ABRs) and micro-CT x-ray scans to measure changes in the development of the auditory periphery in H and CF pups manipulated at postnatal day (P)1, P5, or P9. We found evidence of changes in hearing development in H and CF pups compared with naive pups, including changes in the percentage of animals with ABRs during development, a decrease in ABR thresholds between P13 and P15, and anatomical results consistent with an accelerated formation of the middle ear cavity and opening of the ear canal. Biochemical measurements showed elevated levels of thyroid hormone in plasma from naive and CF pups. These results provide evidence that manipulations of maternal care accelerate hearing onset in Wistar rats. Understanding the mechanisms by which maternal care affects hearing onset opens new opportunities to study experience-dependent development of mammalian hearing.


Subject(s)
Auditory Pathways/growth & development , Ear/growth & development , Hearing/physiology , Maternal Behavior , Acoustic Stimulation , Age Factors , Analysis of Variance , Animals , Animals, Newborn , Auditory Pathways/physiology , Corticosterone/metabolism , Enzyme-Linked Immunosorbent Assay , Evoked Potentials, Auditory, Brain Stem/physiology , Female , Imaging, Three-Dimensional , Insulin-Like Growth Factor I/metabolism , Pregnancy , Rats , Rats, Wistar , Tomography Scanners, X-Ray Computed
13.
J Neurotrauma ; 30(7): 580-90, 2013 Apr 01.
Article in English | MEDLINE | ID: mdl-23234254

ABSTRACT

The similarities and differences between acute nonconvulsive seizures (NCS) and other epileptic events, for example, periodic epileptiform discharges (PED) and intermittent rhythmic delta activities (IRDA), were characterized in rat models of penetrating and ischemic brain injuries. The NCS were spontaneously induced by either unilateral frontal penetrating ballistic-like brain injury (PBBI) or permanent middle cerebral artery occlusion (pMCAO), and were detected by continuous electroencephalogram (EEG) monitoring begun immediately after the injury and continued for 72 h or 24 h, respectively. Analysis of NCS profiles (incidence, frequency, duration, and time distribution) revealed a high NCS incidence in both injury models. The EEG waveform expressions of NCS and PED exhibited intrinsic variations that resembled human electrographic manifestations of post-traumatic and post-ischemic ictal and inter-ictal events, but these waveform variations were not distinguishable between the two types of brain injury. However, the NCS after pMCAO occurred more acutely and intensely (latency=0.6 h, frequency=25 episodes/rat) compared with the PBBI-induced NCS (latency=24 h, frequency=10 episodes/rat), such that the most salient features differentiating post-traumatic and post-ischemic NCS were the intensity and time distribution of the NCS profiles. After pMCAO, nearly 50% of the seizures occurred within the first 2 h of injury, whereas after PBBI, NCS occurred sporadically (0-5%/h) throughout the 72 h recording period. The PED were episodically associated with NCS. By contrast, the IRDA appeared to be independent of other epileptic events. This study provided comprehensive comparisons of post-traumatic and post-ischemic epileptic profiles. The identification of the similarities and differences across a broad spectrum of epileptic events may lead to differential strategies for post-traumatic and post-stroke seizure interventions.


Subject(s)
Brain Ischemia/complications , Epilepsy/etiology , Head Injuries, Penetrating/complications , Seizures/etiology , Animals , Brain Ischemia/physiopathology , Disease Models, Animal , Electroencephalography , Epilepsy/physiopathology , Head Injuries, Penetrating/physiopathology , Male , Rats , Rats, Sprague-Dawley , Seizures/physiopathology
14.
PLoS Biol ; 8(6): e1000393, 2010 Jun 08.
Article in English | MEDLINE | ID: mdl-20543991

ABSTRACT

The mammalian target of rapamycin (mTOR) complex 2 (mTORC2) is a multimeric signaling unit that phosphorylates protein kinase B/Akt following hormonal and growth factor stimulation. Defective Akt phosphorylation at the mTORC2-catalyzed Ser473 site has been linked to schizophrenia. While human imaging and animal studies implicate a fundamental role for Akt signaling in prefrontal dopaminergic networks, the molecular mechanisms linking Akt phosphorylation to specific schizophrenia-related neurotransmission abnormalities have not yet been described. Importantly, current understanding of schizophrenia suggests that cortical decreases in DA neurotransmission and content, defined here as cortical hypodopaminergia, contribute to both the cognitive deficits and the negative symptoms characteristic of this disorder. We sought to identify a mechanism linking aberrant Akt signaling to these hallmarks of schizophrenia. We used conditional gene targeting in mice to eliminate the mTORC2 regulatory protein rictor in neurons, leading to impairments in neuronal Akt Ser473 phosphorylation. Rictor-null (KO) mice exhibit prepulse inhibition (PPI) deficits, a schizophrenia-associated behavior. In addition, they show reduced prefrontal dopamine (DA) content, elevated cortical norepinephrine (NE), unaltered cortical serotonin (5-HT), and enhanced expression of the NE transporter (NET). In the cortex, NET takes up both extracellular NE and DA. Thus, we propose that amplified NET function in rictor KO mice enhances accumulation of both NE and DA within the noradrenergic neuron. This phenomenon leads to conversion of DA to NE and ultimately supports both increased NE tissue content as well as a decrease in DA. In support of this hypothesis, NET blockade in rictor KO mice reversed cortical deficits in DA content and PPI, suggesting that dysregulation of DA homeostasis is driven by alteration in NET expression, which we show is ultimately influenced by Akt phosphorylation status. These data illuminate a molecular link, Akt regulation of NET, between the recognized association of Akt signaling deficits in schizophrenia with a specific mechanism for cortical hypodopaminergia and hypofunction. Additionally, our findings identify Akt as a novel modulator of monoamine homeostasis in the cortex.


Subject(s)
Carrier Proteins/physiology , Dopamine/metabolism , Norepinephrine Plasma Membrane Transport Proteins/physiology , Prefrontal Cortex/metabolism , Schizophrenia/physiopathology , Animals , Carrier Proteins/genetics , Mice , Mice, Knockout , Phosphorylation , Proto-Oncogene Proteins c-akt/chemistry , Proto-Oncogene Proteins c-akt/metabolism , Rapamycin-Insensitive Companion of mTOR Protein , Serine/metabolism , Signal Transduction , Trans-Activators/metabolism , Transcription Factors
15.
J Neurophysiol ; 101(5): 2328-38, 2009 May.
Article in English | MEDLINE | ID: mdl-19279146

ABSTRACT

The stimulus-evoked response of a cortical neuron depends on both details of the afferent signal and the momentary state of the larger network in which it is embedded. Consequently, identical sensory stimuli evoke highly variable responses. Using simultaneous recordings of thalamic barreloid and/or cortical barrel neurons in the rat whisker-to-barrel pathway, we determined the extent to which the responses of pairs of cells covary on a trial-by-trial basis. In the thalamus and cortical layer IV, a substantial component of trial-to-trial variability is independent of the specific parameters of the stimulus, probed here using deflection angle. These stimulus-nonspecific effects resulted in greater-than-chance similarities in trial-averaged angular tuning among simultaneously recorded pairs of barrel neurons. Such effects were not observed among simultaneously recorded thalamic and cortical barrel neurons, suggesting strong intracortical mechanisms of synchronization. Sensory adaptation produced by prior whisker deflections reduced response magnitudes and enhanced the joint angular tuning of simultaneously recorded neurons. Adaptation also decorrelated stimulus-evoked responses, rendering trial-by-trial responses of neuron pairs less similar to each other. Adaptation-induced decorrelation coupled with sharpened joint tuning could enhance the saliency of cells within thalamus or cortex that continue to fire synchronously during ongoing tactile stimulation associated with active touch.


Subject(s)
Action Potentials/physiology , Adaptation, Physiological/physiology , Sensory Receptor Cells/physiology , Somatosensory Cortex/cytology , Vibrissae/physiology , Afferent Pathways/cytology , Afferent Pathways/physiology , Animals , Biophysical Phenomena , Brain Mapping , Evoked Potentials, Somatosensory/physiology , Female , Physical Stimulation/methods , Rats , Rats, Sprague-Dawley , Reaction Time/physiology , Somatosensory Cortex/pathology , Thalamus/cytology , Thalamus/physiology
17.
Cereb Cortex ; 17(3): 599-609, 2007 Mar.
Article in English | MEDLINE | ID: mdl-16632642

ABSTRACT

Response modulation by prior sensory stimulation is a common property of cortical neurons. The degree to which effects are specific to the adapting stimulus provides insights into properties of the underlying circuitry. Here, we examined the effects of an adapting whisker deflection's angle on the angular tuning of layer IV barrel neurons and their major input source, thalamic barreloid neurons. In both barrel regular-spike units (RSUs) and fast-spike units (FSUs), presumed excitatory and inhibitory neurons, prior whisker deflections suppressed subsequent test deflections in a largely angularly nonspecific manner, that is, adaptation in one direction reduced responses for test deflections of all angles. FSUs were poorly tuned for deflection angle and remained so after adaptation. In adapted RSUs, responses to suboptimal directions were suppressed most and angular preferences remained constant; tuning therefore became sharper. Adaptation effects in RSUs and FSUs do not appear to reflect corresponding changes in thalamic neurons. The angularly nonspecific suppression of barrel neurons is likely mediated by local intrabarrel suppressive interactions, such as broadly tuned inhibition and/or short-term synaptic depression of excitatory connections. The dominance of angularly nonspecific suppression suggests that barrel neurons interact largely in an angularly nonspecific manner to reinforce stimulus preferences encoded by their synchronously firing thalamic inputs.


Subject(s)
Neural Inhibition/physiology , Somatosensory Cortex/physiology , Thalamus/physiology , Vibrissae/physiology , Adaptation, Physiological/physiology , Animals , Female , Neural Pathways , Physical Stimulation , Rats , Rats, Sprague-Dawley , Somatosensory Cortex/cytology , Synapses/physiology , Thalamus/cytology , Vibrissae/innervation
19.
J Neurosci ; 23(29): 9565-74, 2003 Oct 22.
Article in English | MEDLINE | ID: mdl-14573536

ABSTRACT

In the rodent somatosensory cortex, whisker-related barrels in layer IV are morphological counterparts of functional cortical columns that extend throughout the cortical depth. We used microelectrode recordings and spike-triggered averaging of field potentials evoked by single thalamic barreloid neurons to investigate functional thalamocortical microcircuits. The function of such circuits was probed by deflecting the principal whisker of a barrel in different angular directions. We found that individual barrels contain minicolumns of neurons preferring the same deflection angle. Angular tuning domains are established by convergent inputs from thalamocortical cells with corresponding angular preferences. Processing within such domains may depend on local connectivity among vertically aligned barrel neurons.


Subject(s)
Somatosensory Cortex/physiology , Thalamus/physiology , Action Potentials/physiology , Animals , Female , Microelectrodes , Nerve Net/physiology , Neurons/physiology , Physical Stimulation/methods , Rats , Rats, Sprague-Dawley , Somatosensory Cortex/anatomy & histology , Thalamus/cytology , Vibrissae/innervation , Vibrissae/physiology
SELECTION OF CITATIONS
SEARCH DETAIL
...