Qingquan Lian

Establishment of a Rat Model of Type II Diabetic Neuropathic Pain

OBJECTIVE To establish a rat model of type II diabetic neuropathic pain. METHODS Sixty Sprague Dawley rats were randomly divided into two groups: group A (N = 10) was fed a normal diet, and group B (N = 50) was fed a high-fat and high-sugar diet. After 8 weeks, the body weight of all rats was recorded, and rats in both groups had their fasting plasma glucose, insulin concentration, and insulin sensitivity index measured and calculated. Subsequently, the rats in group B were randomly divided into three subgroups that were each given different doses of streptozotocin (STZ) by a single intraperitoneal injection (subgroup B1 received 30 mg/kg, subgroup B2 received 35 mg/kg, and subgroup B3 40 mg/kg). Two weeks after the STZ injection, the four groups of rats had their insulin sensitivity index, mechanical withdrawal threshold, and thermal withdrawal latency assessed, allowing us to establish a rat model of type II diabetic neuropathic pain and to determine the optimum dose of STZ. Four weeks after STZ injection (2 weeks after the model was established), the pain threshold was measured in the rats in group A and the group treated with the most effective STZ dose. We also measured the expression of phosphorylated extracellular signal-regulated kinase (p-ERK), phosphorylated cyclic AMP response element-binding protein (p-CREB), and phosphorylated N-methyl d-aspartate receptor subtype B (p-NR2B) in the dorsal root ganglion (DRG) and spinal cord dorsal horn regions, which are closely related to neuropathic pain, and also recorded the TTX-R sodium currents in the acutely isolated DRG neurons. RESULTS After 8 weeks of a high-fat, high-sugar diet, the body weight of the rats in group B was significantly increased. Although the fasting blood glucose levels did not change significantly, the fasting insulin levels were slightly elevated, and the insulin sensitivity index was significantly reduced. Two weeks after STZ injection, the blood glucose levels of the rats in subgroup B1 were elevated but did not remain so for a prolonged period. In contrast, the rats in subgroup B3 had elevated blood glucose that was accompanied by a high mortality rate, while the blood glucose levels of the rats in subgroup B2 were moderately elevated and relatively stable. In addition, the pain threshold was significantly decreased (P < 0.05), and the mortality was low in this group. Because of this, the dose of STZ that was used in group B2 was considered the most effective dose of STZ for induction of diabetes. Four weeks after STZ injection, the pain threshold in the rats of group B2 was still significantly decreased, and the expression of p-ERK, p-CREB, and p-NR2B in the dorsal root ganglion (DRG) and spinal cord dorsal horn was significantly increased. The tetrodotoxin-resistant sodium current density in DRG neurons was also significantly elevated (P < 0.05). CONCLUSIONS A rat model of type II diabetic neuropathic pain can be established by feeding rats a high-fat, high-sugar diet for 8 weeks, in combination with intraperitoneal injection of 35 mg/kg STZ. This model can be stably maintained for at least 2 weeks.

The effect of propofol on intrathecal morphine-induced pruritus and its mechanism.

BACKGROUND:Previous studies have shown that a low dose of propofol IV bolus had a beneficial effect on intrathecal morphine-induced pruritus in humans. However, its exact mechanism has not been fully understood. In this study, we hypothesized that propofol relieved intrathecal morphine-induced pruritus in rats by upregulating the expression of cannabinoid-1 (CB[1]) receptors in anterior cingulate cortex (ACC). METHODS:Twenty-four Sprague-Dawley rats were divided into a control group and 20, 40, 80 &mgr;g/kg morphine groups to create an intrathecal morphine-induced scratching model. The effects of propofol on intrathecal 40 &mgr;g/kg morphine-induced scratching responses were then evaluated. Sixty rats were randomly assigned to control, normal saline, intralipid, and propofol groups, with pruritus behavior observation or killed 8 minutes after venous injection of normal saline, intralipid, or propofol, and brain tissues were then collected for assay. Immunohistochemistry was then performed to identify the expression of CB (1) receptor in ACC, and the concentration of CB(1) receptor in ACC was determined by Western blot analysis. RESULTS:Compared with the control group, rats in the 20, 40, 80 &mgr;g/kg morphine groups had higher mean scratching response rates after intrathecal morphine injection (P =0.020, 0.005, and 0.002, respectively). There was a statistical difference between 20 and 40 &mgr;g/kg morphine groups at 10 to 15 and 15 to 20 timepoints after intrathecal morphine injection (P = 0.049 and 0.017, respectively). Propofol almost abolished the scratching response that was induced by 40 &mgr;g/kg intrathecal morphine injection (F[2, 15] = 46.87, P < 0.001; F[22, 165] = 2.37, P = 0.001). Compared with the intralipid and normal saline groups, the scratching behavior was significantly attenuated in the propofol group (P < 0.001). Compared with control, normal saline, and intralipid groups, the protein expression of CB(1) receptor in ACC (Western blot) in the propofol group increased (0.86 ± 0.21, 0.94 ± 0.18, 0.86 ± 0.13, and 1.34 ± 0.32, respectively, P < 0.001). There was no significant difference among control, normal saline, and intralipid groups. Compared with the control, normal saline, and intralipid groups, the average number of neurons of CB(1) receptor in the ACC area were higher in the propofol group (21.0 ± 1.4, 19.3 ± 1.8, 24.8 ± 7.7, and 37.2 ± 3.3, respectively, P < 0.001). CONCLUSIONS:Morphine elicits dose-independent scratching responses after intrathecal injection in rats. Morphine 40 &mgr;g/kg intrathecal injection-induced scratching responses can be prevented by propofol. Increased protein expression of CB(1) receptors in ACC may contribute to the reversal of intrathecal morphine-induced scratching.

Analgesic efficacy of ultrasound-guided subcostal transversus abdominis plane block

Background: To evaluate the analgesic efficacy on defined areas of the abdomen and back after ultrasound-guided subcostal transversus abdominis plane (TAP) block using 0.25% levobupivacaine 0.5 mL/kg. Methods: Twenty patients undergoing elective laparoscopic cholecystectomy, between 20 and 60 years of age with operative time <1 hour, received subcostal TAP block using 0.25% levobupivacaine 0.5 mL/kg on the left side. Surgery started after 1 hour of observation. Sensory assessment was undertaken using pinprick and 75% ethyl alcohol at 10, 20, 30 minutes, 1, 3, and 12 hours after TAP block at 19 testing zones that were divided by anatomic landmark lines on the abdomen and the back. Efficacy of zone was defined as loss of cold temperature sensation or loss of pinprick pain sensation in more than 50% patients in that testing zone. Duration was determined by analgesia and loss of temperature sensation beginning within 30 minutes of TAP block placement lasting until time points of 1, 3, and 12 hours. All of the testing zones were divided as Group I effective at 20 minutes in less than 50% patients (0%–50%), Group II 50% to 70% patients, Group III 70% to 90% patients, and Group IV 90% to 100% patients. Results: Twenty patients meeting the study requirements were included. At each time point, the efficacies among 4 groups were significantly different. Subcostal TAP had good efficacy and stable duration in zones 1, 2, 3, 5, and 6. Conclusion: Subcostal TAP block with 0.25% levobupivacaine 0.5 mL/kg dose provided effective analgesia in the anterior abdominal wall between medioventral line to anterior axillary line except the lateral upper abdominal region.

Pediatric preoperative risk factors to predict postoperative ICU admission and death from a multicenter retrospective study.

Although some studies have investigated the potential predictors of perioperative mortality, there are few specifically for pediatrics.

Anatomic variations of neck vessels and the course of pediatric internal jugular veins.

Landmark‐guided internal jugular vein cannulation is difficult for pediatric patients but useful, especially when ultrasound equipment is unavailable. Therefore, it is important to define the adjacent anatomic characteristics of the pediatric internal jugular vein.

Bezold–jarisch reflex occurred in a pediatric patient with giant intra-abdominal teratoma during induction of anesthesia: A case report

Rationale: Bezold–Jarisch reflex (BJR) occurs when the cardioinhibitory receptors in the walls of ventricles are activated by various stimuli, with typical features of bradycardia, vasorelaxation, and hypotension. This reflex usually happens in parturient intrathecal anesthesia, as a result of decreased venous return by compression of inferior vena cava, but it is only rarely reported during general anesthesia. Patient concerns: Severe bradycardia and hypotension, indicating BJR, occurred during the induction of general anesthesia in a 3-month-old female child with giant intra-abdominal teratoma. Diagnoses: A giant intra-abdominal teratoma was detected by computed tomography scanning. The decreased left ventricular ejection faction along with increased troponin I and N-terminal pro-B-type natriuretic peptide indicated a preoperative mild cardiac dysfunction. BJR was diagnosed on the basis of the severe bradycardia and hypotension observed during the induction of general anesthesia, Interventions: Atropine failed to increase heart rate. Cardiopulmonary resuscitation was initiated immediately and epinephrine was injected intravenously because of sudden circulatory collapse. Soon after the return of spontaneous circulation, a central venous line was placed and invasive blood pressure was monitored. Vital signs and homeostasis were kept stable during teratoma resection. Outcomes: The child was extubated after emergence from anesthesia in the operating room. Eleven days later, she had recovered without complications and was discharged. Lessons: General anesthesia should be induced with great care in patients with giant intra-abdominal masses, and the patient should be kept in the left-lateral table tilt position before induction.