Hippocampal Threat Reactivity Interacts with Physiological Arousal to Predict PTSD Symptoms

Hippo campal impairments are reliably associated with post-traumatic stress disorder (PTSD); however, little research has characterized how increased threat sensitivity may interact with arousal responses to alter hippocampal reactivity, and further how these interactions relate to the sequelae of trauma-related symptoms. In a sample of individuals recently exposed to trauma (N = 116, 76 female), we found that PTSD symptoms at 2 weeks were associated with decreased hippocampal responses to threat as assessed with fMRI. Further, the relationship between hippocampal threat sensitivity and PTSD symptomology only emerged in individuals who showed transient, high threat-related arousal, as assayed by an independently collected measure of fear potentiated startle. Collectively, our finding suggests that development of PTSD is associated with threat-related decreases in hippocampal function because of increases in fear-potentiated arousal.SIGNIFICANCE STATEMENT Alterations in hippocampal function linked to threat-related arousal are reliably associated with post-traumatic stress disorder (PTSD); however, how these alterations relate to the sequelae of trauma-related symptoms is unknown. Prior models based on nontrauma samples suggest that arousal may impact hippocampal neurophysiology leading to maladaptive behavior. Here we show that decreased hippocampal threat sensitivity interacts with fear-potentiated startle to predict PTSD symptoms. Specifically, individuals with high fear-potentiated startle and low, transient hippocampal threat sensitivity showed the greatest PTSD symptomology. These findings bridge literatures of threat-related arousal and hippocampal function to better understand PTSD risk.

Soluble interleukin-2 receptor and interleukin-8 plasma levels during and after cardiopulmonary bypass: correlations with creatine kinase and creatine kinase MB

In this study, soluble receptor of interleukin-2, interleukin-8, creatine kinase, and creatine kinase MB isoenzyme levels were determined serially before, during, and after cardiopulmonary bypass in blood samples of 24 patients. Interleukin-2 receptor levels were 683+/-80 U/ml in the preoperative period and 640+/-60 U/ml during hypothermia. Subsequently, these levels increased significantly at the end of the procedure (791+/-70 U/ml, P<0.01), remaining elevated 1 h after (882+/-92 U/ml, P<0.001) and reaching peak values 24 h postoperatively (1,752+/-200 U/ml, P<0.001). Preoperative plasma values of interleukin-8 were 230+/-43 pg/ml. Interleukin-8 concentrations were 185+/-25 pg/ml during hypothermia. The peak interleukin-8 levels were observed at the end of cardiopulmonary bypass (754+/-94 pg/ml, P<0.001) and tended to decrease 1 h after the procedure (643+/-76 pg/ml, P<0.001), declining to preoperative values, 24 h postoperatively (273+/-41 pg/ml). Interleukin-2 receptor levels correlated well with creatine kinase levels during the procedure. Furthermore, creatine kinase MB levels were correlated with interleukin-2 receptor values only at the end and 1 h after completion of cardiopulmonary bypass. We concluded that interleukin-8 and Interleukin-2 receptor levels are elevated after cardiopulmonary bypass and may contribute to myocardial injury as reflected by increased levels of creatine kinase and creatine kinase MB and correlations between interleukin-2 receptor and both creatine kinase and creatine kinase MB levels.

Clonidine pretreatment inhibits stress-induced gastric ulcer in rats

We studied the effects of clonidine (0.5 mg/kg) on hormonal stress response and antioxidant enzymes cold restraint-induced gastric lesions in rats. Rats in the study group were given 0.5 mg/kg intraperitoneal clonidine (n = 12), whereas the control group received 0.5 mL/kg intraperitoneal isotonic sodium chloride solution (n = 9). Animals were then subjected to immobilization at 4 degrees C in restraining devices for 4 h after a starvation period of 24 h. Gastric lesion index, gastric tissue malondialdehyde activity, and plasma cortisol concentrations were assayed. Histopathologic examination demonstrated a stress ulcer index of 3.17+/-0.92 mm in the clonidine group and 14.0+/-3.22 mm in the control group (P<0.05). The tissue malondialdehyde concentrations were slightly higher in the control group than in the clonidine group, but the differences were not statistically significant (P>0.05). Plasma cortisol levels were lower in the clonidine group (P<0.05). We concluded that clonidine attenuated the tissue damage and stress response in stress-induced gastric ulceration.

IMPLICATIONS

Stressful circumstances can cause stomach ulcers, which can bleed, exposing patients to potentially life-threatening complications. In the present animal study, we showed that clonidine, a routinely available medication, may be useful in preventing stress-induced stomach ulcers.

Comparison of caudal bupivacaine, bupivacaine-morphine and bupivacaine-midazolam mixtures for post-operative analgesia in children

Sixty children undergoing inguinal or urogenital surgery were allocated randomly to three groups to receive a caudal injection of either 0.125% bupivacaine 0.75 mL kg-1 with 0.5% midazolam 50 micrograms kg-1 (n = 20) or with 1% morphine chlorhydrate 0.05 mg kg-1 (n = 20), or bupivacaine alone (n = 20) after surgery under general anaesthesia. There were no significant changes in heart rate, blood pressure, respiratory rate or oxygen haemoglobin saturation values in all groups, and there were no significant differences in the incidence of vomiting and pruritus between the groups (P > 0.05). Sedation scores were higher in the bupivacaine-midazolam and the bupivacaine-morphine groups than in the bupivacaine group at 8-12 h post-operatively (P < 0.01). The durations of analgesia were 21.15 +/- 1.2 h in the bupivacaine-midazolam group, 14.50 +/- 1.6 h in the bupivacaine-morphine group and 8.15 +/- 1.3 h in the bupivacaine group. Differences between the bupivacaine-midazolam group and the bupivacaine group (P < 0.001), the bupivacaine-midazolam group and the bupivacaine-morphine group (P < 0.01), and the bupivacaine-morphine group and the bupivacaine group (P < 0.01) were significant. It is suggested that caudal administration of a bupivacaine-midazolam mixture produces a longer duration of post-operative analgesia than a bupivacaine-morphine mixture and bupivacaine alone with sedation for 8-12 h post-operatively.