[Preventing and treating anterior commissure adhesion with mucosal flap: a study in canines and clinical cases].

Objective: To evaluate the effectiveness of mucosal flap combined with silicone keel for preventing and treating anterior commissure adhesion in canines and clinical cases. Methods: A prospective experiment was performed from November 2019 to June 2021. Twenty five canines were randomly divided into 5 groups(A, B, C, D, E). Group A, B, C, D received anterior commissure injury by CO2 laser, then separately treated with free mucosal flap-keel complex,intralaryngeal mucosal flap-keel complex, silicone keels and without treatment, group E didn't injure the vocal cord after intubation. The keel was removed after 2 weeks, the larynx was harvested after 4 weeks. The effectiveness of anterior commissure adhesion prevention was evaluated by manifestation under laryngoscope, standard vocal cord length and standard glottic area. A retrospective analysis was performed on sixteen patients with anterior commissure lesion, who underwent mucosal flap-keel technique in Huashan Hospital of Fudan University from January 2019 to January 2021 (10 cases with free mucosal flap-keel complex and 6 cases with intralaryngeal mucosal flap-keel complex). All the patients underwent evaluation of laryngeal function included manifestation under laryngoscope each month and voice analysis before and 3 month after surgery. SPSS 20.0 software was used for statistical analysis. Results: No surgery accident or complication happened in canines and patients. The standard vocal cord length and standard glottic area after 4 weeks in group B were significantly higher than those in group A, C, D (Hstandard vocal cord length=31.688, Hstandard glottic area=16.444, P<0.05). The standard vocal cord length and standard glottic area after 4 weeks in group A were also significantly higher than those in group C, D(Hstandard vocal cord length=20.936, Hstandard glottic area=11.786, P<0.05). The standard vocal cord length and standard glottic area after 4 weeks in group A, B, E were not significantly different to that before surgery(tA left standard vocal cord length=2.636, tA right standard vocal cord length=2.582, tB left standard vocal cord length=2.707, tB right standard vocal cord length=2.673, tE left standard vocal cord length=0.370, tE right standard vocal cord length=0.821, tA standard glottic area=2.731, tB standard glottic area=2.753, tE standard glottic area=-0.529, P>0.05). The standard vocal cord length and standard glottic area after 4 weeks in group C, D were significantly lower than those before surgery(tC left standard vocal cord length=16.137, tC right standard vocal cord length=13.984, tD left standard vocal cord length=11.903, tD right standard vocal cord length=14.587, tC standard glottic area=10.280, tD standard glottic area=22.974, P<0.05). During 6-18 months of follow-up in clinical patients, no one developed a glottic web. Three months after surgery, Jitter, Shimmer, noise to harmonic ratio(NHR), the maximum phonation time(MPT)in all patients were significantly different from preoperative(tintralaryngeal mucosal flap jitter=24.885, tintralaryngeal mucosal flap shimmer=22.643, tintralaryngeal mucosal flap NHR=6.202, tintralaryngeal mucosal flap MPT=-9.661, tfree mucosal flap jitter=25.459, tfree mucosal flap shimmer=18.683, tfree mucosal flap NHR=5.705, tfree mucosal flap MPT=-20.840, P<0.05). Conclusion: Mucosal flap combined with silicone keel is an effective technique for preventing and treating anterior commissure adhesion. The effect of pedicled intralaryngea lmucosal flap is better.

Oral Nutritional Supplement with ß-hydroxy-ß-methylbutyrate (HMB) Improves Nutrition, Physical Performance and Ameliorates Intramuscular Adiposity in Pre-Frail Older Adults: A Randomized Controlled Trial.

OBJECTIVES: Supplementation of high protein oral nutrition shakes supplemented with ß-hydroxy-ß-methylbutyrate (HP-HMB) has been shown to improve muscle mass, muscle strength, and physical performance in older adults, but the roles of HP-HMB supplementation on the intramuscular adiposity remained unknown. This 12-week randomized controlled trial evaluated the changes of muscle mass, muscle strength, physical performance and intramuscular adiposity among community-dwelling pre-frail older persons. METHODS: This was an open-label, parallel group, randomized controlled trail that enrolled 70 community-dwelling pre-frail older persons without active or uncontrolled conditions, disability or dementia. The intervention group was provided with two services of HP HMB (Ensure® Plus Advance containing 3g HMB) per day for 12 weeks, and the control group was provided with professional nutritional counselling for sufficient protein intake. All participants received functional assessments, laboratory tests and magnetic resonance imaging (MRI) of the dominant leg before and after study. Intramuscular adipose tissue (IMAT) and the mid-thigh cross-sectional area (CSA) of muscle were obtained by MRI, and the IMAT-to-CSA ratio was calculated to evaluate intramuscular adiposity. RESULTS: Overall, 62 participants (mean age: 71.1±3.8 years, 69.4% female) completed the study (HP-HMB group: 29, control group: 33) and comparisons of baseline characteristics between groups were not statistically different. For the primary outcome, HP-HMB group showed significant improvements in the CSA of mid-thigh muscle (mean increase of CSA: 149.1±272.3 for HMB group vs -22.9±309.1 mm2 for control group, P=0.045). The improvement of MNA-SF was borderline (0.28±0.75 vs. -0.15±0.94, P=0.064), but serum levels of Vit D were significantly increased in the HMB group (3.83±8.18 vs. -1.30±4.81 ng/mL, P=0.002). Moreover, the body weight and BMI were significantly increased in the HMB group (1.10±1.18 vs. 0.24±1.13 kg, P=0.005; 0.56±0.68 vs. 0.22±0.47 kg/m2, P=0.019). In particular, the IMAT-to-CSA ratio was reduced in the HMB group (-0.38±1.21 vs. -0.02±2.56 %, P=0.06). Using the generalized estimating equation, we found that SPPB score in chair rise test was significantly improved (ß=0.71, 95% C.I.0.09-1.33, P=0.026). CONCLUSIONS: The 12-week supplementation with high protein oral nutrition shake supplemented with 3g HMB per day significantly increased muscle mass, as well as nutritional status and physical performance, and ameliorated the intramuscular adiposity of pre-frail older persons. Further study is needed to explore the long-term benefits of HP-HMB supplementation on muscle and metabolic health for older adults.

Illuminating gravitational waves: A concordant picture of photons from a neutron star merger.

Merging neutron stars offer an excellent laboratory for simultaneously studying strong-field gravity and matter in extreme environments. We establish the physical association of an electromagnetic counterpart (EM170817) with gravitational waves (GW170817) detected from merging neutron stars. By synthesizing a panchromatic data set, we demonstrate that merging neutron stars are a long-sought production site forging heavy elements by r-process nucleosynthesis. The weak gamma rays seen in EM170817 are dissimilar to classical short gamma-ray bursts with ultrarelativistic jets. Instead, we suggest that breakout of a wide-angle, mildly relativistic cocoon engulfing the jet explains the low-luminosity gamma rays, the high-luminosity ultraviolet-optical-infrared, and the delayed radio and x-ray emission. We posit that all neutron star mergers may lead to a wide-angle cocoon breakout, sometimes accompanied by a successful jet and sometimes by a choked jet.

[Technical guideline for human rabies prevention and control (2016)].

In order to promote the prevention and control programs on rabies in our country, to regulate the prevention and disposition of rabies and to reduce the deaths caused by rabies, the Chinese Center for Disease Control and Prevention has organized a panel of experts, in the reference with Guidelines issued by WHO, American Advisory Committee on Immunization Practices, and the latest research progress from home and abroad, and compiled this document-"Technical Guidelines for Human Rabies Prevention and Control (2016)". The Guidelines conducted a systematic review on the etiology, clinical characteristics, laboratory diagnosis, epidemiology of rabies and provided evidence on varieties, mechanisms, effects, side-effects and security of rabies vaccine, as well as on other preparations on passive immunity of its kind, on methods related to prevention and disposition of exposure etc, finally to have come up with the recommendation on the above mentioned various techniques. The guidelines will be used by staff working on prevention and control of rabies from the Center for Disease Control and Prevention at all levels, from the departments of outpatient and divisions of infection and emergency control in all the medical institutions. The guideline will be updated and revised, following the research progress from home and abroad.

The Ankle-Brachial Index is Associated With Cardiovascular Complications After Noncardiac Surgery.

BACKGROUND: This study evaluated the association of the ankle-brachial index (ABI) and cardiovascular complications after noncardiac surgery. METHODS: We prospectively evaluated patients referred for noncardiac surgery. The ABI was performed before surgery. Patients with abnormal ABI (≤ 0.9) were included in the peripheral artery disease (PAD) group and the remaining constituted the control group. Cardiac troponin and electrocardiogram were obtained 72 hours after surgery. Patients were followed up to 30 days, and primary end point was the occurrence of any cardiovascular event: cardiovascular death, acute coronary syndrome, isolated troponin elevation (ITE), decompensated heart failure, cardiogenic shock, unstable arrhythmias, nonfatal cardiac arrest, pulmonary edema, stroke, or PAD symptoms increase. RESULTS: We evaluated 124 patients (61.3% male; mean age 65.4 years). During the study, 57.9% of patients in the PAD group had an event versus 25.7% in the control group (P = .011). The ITE was the most observed event (24.2%). After logistic regression, the odds ratio for ITE was 7.4 (95% confidence interval 2.2-25.0, P = .001). CONCLUSIONS: In patients submitted to noncardiac surgery, abnormal ABI is associated with a higher occurrence of a cardiovascular event.

Quantification of macrovesicular and microvesicular hepatic steatosis in rats using 3.0-T ¹H-magnetic resonance spectroscopy.

BACKGROUND AND OBJECTIVE: Hepatic steatosis (HE), which is common among the general population, is present in donor organs, potentially affecting their graft survival as well as the recovery of the donor. Our goal was to develop an experimentally and clinically reliable, noninvasive method to quantify macrovesicular and microvesicular hepatic steatosis using 3-T (1)H-magnetic resonance spectroscopy (MRS). MATERIALS AND METHODS: Macrovesicular and microvescular steatosis were induced in rats using methylcholine deficiency and choline deficiency diets. A MayoBC10 coil was used for radiofrequency transmission and signal recept. Measurements of hepatic fat content were performed using (1)H spectroscopy on a 3.0-T whole-body GE Signa system. The ratio of the areas under the curve of fat (0.8-1.3 ppm) and water (4.7 ppm) was used to determine hepatic fat content, which was compared with the degree of histopathologic and biochemical steatosis. RESULTS: Twenty rats were divided into two groups based on the percentage of microvesicular liver steatosis. Group A (n = 13) was the lower percentage group (microvesicular < 10%) while group B (n = 7), the higher group (microvesicular ≥ 10%). The mean total fatty change in the liver was 58.4% ± 47.2% and 67.6% ± 39.1% in groups A and B, respectively. A highly significant linear correlation between (1)H-MRS and total fatty change was observed in group A (r = .986, P < .001) while there was a relatively poor correlation in group B (r = .764, P = .05). The power to predict fatty change in the liver in groups A and B was significantly different (P = .004). CONCLUSIONS: The degree of hepatic steatosis with a small amount of microvesicular steatosis (<10%) can be precisely predicted using 3-T (1)H-MRS.

Delayed spontaneous hepatogastric fistula formation following transcatheter arterial embolisation and radiotherapy for hepatocellular carcinoma.

A 58-year-old male patient with an unresectable 10 cm liver lesion that was a histologically proven hepatocellular carcinoma (HCC) underwent transcatheter hepatic artery embolisation (TAE). 4 months later, the patient was referred for salvage radiotherapy owing to local recurrence. The HCC became an encapsulated tumour with central necrosis after radiotherapy. The patient enjoyed a normal lifestyle for 9 years, with local control achieved by radiotherapy, until a hepatogastric fistula developed. Although the hepatogastric fistula resolved with surgical drainage, the patient later died from septic shock. Hepatogastric fistula is a rare but serious complication after TAE and radiotherapy for HCC. Development of fever, abdominal pain and jaundice after an initial symptom-free interval should arouse suspicion of hepatogastric fistula formation from an encapsulated necrotic HCC or a ruptured liver abscess. Because the mortality is high, aspiration of a suspected necrotic lesion should be performed as soon as possible. Patients with risk factors, including liver cirrhosis and large lesions close to the adjacent gastrointestinal tract, are especially vulnerable. Gas formation within a necrotic liver tumour requires immediate drainage.

Microtubule affinity-regulating kinase 2 functions downstream of the PAR-3/PAR-6/atypical PKC complex in regulating hippocampal neuronal polarity.

The PAR-3/PAR-6/atypical PKC (aPKC) complex is required for axon-dendrite specification of hippocampal neurons. However, the downstream effectors of this complex are not well defined. In this article, we report a role for microtubule affinity-regulating kinase (MARK)/PAR-1 in axon-dendrite specification. Knocking down MARK2 expression with small interfering RNAs induced formation of multiple axon-like neurites and promoted axon outgrowth. Ectopic expression of MARK2 caused phosphorylation of tau (S262) and led to loss of axons, and this phenotype was rescued by expression of PAR-3, PAR-6, and aPKC. In contrast, the polarity defects caused by an MARK2 mutant (T595A), which is not responsive to aPKC, were not rescued by the PAR-3/PAR-6/aPKC complex. Moreover, polarity was abrogated in neurons overexpressing a mutant of MARK2 with a deleted kinase domain but an intact aPKC-binding domain. Finally, suppression of MARK2 rescued the polarity defects induced by a dominant-negative aPKC mutant. These results suggest that MARK2 is involved in neuronal polarization and functions downstream of the PAR-3/PAR-6/aPKC complex. We propose that aPKC in complex with PAR-3/PAR-6 negatively regulates MARK(s), which in turn causes dephosphorylation of microtubule-associated proteins, such as tau, leading to the assembly of microtubules and elongation of axons.

Small bowel obstruction due to incarcerated sciatic hernia: ultrasound diagnosis.

A 71-year-old woman presented with vomiting, abdominal pain and vague right gluteal discomfort. Abdominal ultrasound showed ascites and dilated small bowel loops with peristaltic movement, while transgluteal ultrasound revealed entrapped ascites beneath gluteal muscles and an oedematous, immobile bowel loop trapped between the sacrum and iliac bone with barely visible colour Doppler flow suggestive of an incarcerated sciatic hernia. CT demonstrated similar findings and subsequent surgery confirmed the diagnosis. To our knowledge, this is the first report of a pre-operative diagnosis of incarcerated sciatic hernia on ultrasound.

Superior rectal artery injury following lumbar disc surgery. Case report.

Traumatic injury of the aorta, inferior vena cava, and iliac vessels due to penetration of the anterior anulus fibrosus and anterior longitudinal ligament is a recognized complication of lumbar disc surgery. The authors report, to the best of their knowledge, the first case of discectomy-related superior rectal artery injury treated by endovascular intervention.

Malignant phyllodes tumor of the breast metastasizing to the pancreas: case report.

Phyllodes tumor of the breast, or cystosarcoma phyllodes, is an unusual breast tumor. It is usually considered a benign lesion but may have malignant potential. Only a small proportion of malignant phyllodes tumors will metastasize. A phyllodes tumor of the breast metastasizing to the pancreas is rare. This 39-year-old female patient initially presented to us with a 5 x 4 x 2 cm tumor of a right breast. After excision of the tumor, she received another wise excision for a local recurrence of the tumor. Three years had passed when she started having hematemesis and tarry stools intermittently over a period of about one month. Clinical evaluation disclosed a huge mass with an ulcerated and bloody base over the second portion of the duodenum. A pancreatoduodenectomy was then performed. During the postoperative recovery period, a rapidly enlarging tumor of the right breast was noted. She subsequently underwent a total mastectomy of the right breast. Both the duodenal tumor and the breast tumor were found to be malignant phyllodes tumors. The rarity of this kind of patient and presentation is discussed.

Overexpression of vascular endothelin-1 and endothelin-A receptors in a fructose-induced hypertensive rat model.

OBJECTIVE: To examine the temporal relationship between hyperinsulinemia and hypertension in the fructose-hypertensive rat model and to study the function of endothelin-1 (ET-1) in fructose-induced hypertension. DESIGN: Since ET-1 induces insulin resistance in conscious rats, we tested the hypothesis that both hyperinsulinemia and hypertension developed in the fructose-hypertensive rat model might be the sequelae of an elevated tissue content of ET-1 and ET(A) receptors. MATERIALS AND METHODS: Systolic hypertension was induced within 3 weeks in male Sprague-Dawley rats fed on a fructose-rich diet. After continual monitoring of blood pressure and plasma insulin concentrations, the animals were killed at the end of experiment to determine plasma levels of ET-1, the contractile response of aortic rings to ET-1, and ET-1 and ET(A) receptor gene expressions. In a separate experiment, BQ-610 was administered to lower the effect of ET-1 in rats with fructose-induced hypertension. RESULTS: Compared with control rats given normal chow, the fructose-fed rats developed systolic hypertension after 3 weeks of the diet (127+/-3.7 versus 110+/-5.5 mmHg, P < 0.01) and hyperinsulinemia both before (1 07.1+/-32.5 versus 48.5+/-14.3 pmol/l, P < 0.005) and after (96.6+/-63.7 versus 50.4+/-5.6 pmol/l, P< 0.05) they became hypertensive. Although plasma ET-1 levels did not differ between the rat groups, aortic ring contraction-concentration curves, indicating vessel contractility in response to ET-1, were significantly greater in these rats than in controls (F1,72 = 12.34, P< 0.00077). Messenger RNA extracted from the tail arteries and blotted with both ET-1 and ET(A) probes showed that fructose-fed rats had greater ET-1 and ET(A)-receptor gene expression than control rats. Concomitant administration of BQ-610 to rats fed on a fructose diet significantly reduced the hypertension. Conclusions These findings suggest that elevated vascular expression of ET-1 and ET(A) receptor genes may mediate the development of hypertension and hyperinsulinemia in rats fed a fructose-rich diet

The hemodynamic effects of AT-112, an analog of ketanserin, in portal hypertensive rats.

A serotonin mechanism has been reported to contribute to the hyperdynamic circulation of portal hypertension. Different studies have demonstrated that serotonin antagonists decrease portal pressure in portal hypertensive patients and animals. The present study was undertaken to investigate the effect of AT-112, an analog of ketanserin, on portal hypertension induced by partial portal vein ligation in rats. Since ketanserin is known to possess alpha 1-adrenergic antagonistic activity, the effect of AT-112 was compared to that of prazosin. A single dose (prazosin 4.2 micrograms/kg, AT-112 1 mg/kg) was chosen to produce a similar hypotensive effect (-20 +/- 4% for prazosin and -24 +/- 4% for AT-112). At this dose, prazosin significantly decreased total peripheral resistance whereas AT-112 significantly decreased cardiac index and heart rate. Both agents significantly decreased the portal tributary blood flow and portal pressure. In rats receiving AT-112, a significant correlation was found between the magnitudes of decrease in cardiac index and the decrease in portal tributary blood flow. We also found that the magnitude of reduction in portal pressure was greater following AT-112 administration. This study suggested that AT-112 may have more beneficial hemodynamic effects than prazosin in portal hypertensive rats. Our results provide further support for the serotonergic mechanism in the pathogenesis of hyperdynamic circulation in portal hypertension.

Effects of long-term administration of octreotide in portal vein-stenosed rats.

The hemodynamic effects of long-term administration of octreotide in portal hypertension has not been established. In addition, whether long-term octreotide treatment prevents the development of portosystemic shunts has not yet been evaluated. Hence, the current study was undertaken to evaluate the effects of long-term administration of octreotide in rats with portal vein stenosis. Immediately after portal vein stenosis or sham operation, rats were given either a long-term octreotide administration of 100 micrograms/kg or a placebo every 12 hours by subcutaneous injection for 14 consecutive days. Systemic hemodynamics and regional blood flows, degree of mesenteric-systemic shunts, and plasma glucagon concentrations were measured after the final dose of octreotide or placebo. A fifth group of portal vein-stenosed rats received hemodynamic and plasma glucagon measurements after 1-day octreotide treatment given at 14 days after surgery. Long-term octreotide treatment modified the hyperdynamic circulation without affecting the degree of mesenteric-systemic shunts, and 1-day octreotide treatment decreased portal tributary blood flow without affecting the portal pressure, systemic hemodynamics, and degree of mesenteric-systemic shunts. Plasma glucagon levels were decreased in portal vein-stenosed rats receiving either long-term or 1-day octreodtide compared with rats receiving placebo. In contrast, chronic octreotide treatment did not affect any of the hemodynamic values or plasma glucagon levels in sham-operated rats. In conclusion, long-term administration of octreotide modified in part the development of portal hypertension and hyperdynamic circulation in portal vein-stenosed rats without affecting the degree of mesenteric-systemic shunts.

Decreased vascular reactivity of portal vein in rats with portal hypertension.

BACKGROUND/AIMS: Vascular hyporesponsiveness in portal hypertension is well documented in the arterial tissue. The present study aimed to investigate the possible changes in the portal vein from portal hypertensive rats. METHODS: Portal hypertension was induced by partial portal vein ligation. Fourteen days after surgery, portal veins were removed for contractile study and measurement of cAMP, cGMP and [Ca2+]i. RESULTS: In vitro tension preparation showed a decreased maximum response to norepinephrine in portal vein of portal vein ligated rats (38.3 +/- 4.1 vs. 23.4 +/- 1.5 mN/mm2). The pA2 values of WB4101 and yohimbine (alpha1- and alpha2-adrenoceptor antagonist, respectively) were not different between the two groups. Tissue cAMP (14.4 +/- 0.9 vs. 12.2 +/- 0.7 pmol/mg protein), but not cGMP, content was increased and intracellular calcium [Ca2+]i levels (247 +/- 9 vs. 281 +/- 13 nM) were decreased in portal vein ligated rats. CONCLUSIONS: These results showed that in portal vein from portal vein ligated rats, vascular hyporesponsiveness and an increase in basal cAMP content and a decrease in basal [Ca2+]i were observed.

Decreased vascular contractile and inositol phosphate responses in portal hypertensive rats.

The purpose of this study was to investigate the vascular contractile and inositol phosphate responses in portal hypertensive rats. Portal hypertension was induced by partial portal vein ligation (PVL) in Sprague-Dawley rats. Sham-operated rats served as controls. Pressures, vasoconstrictor responses, and inositol phosphate responses were determined at 14 days after surgery. The portal venous pressure was significantly higher, while systemic arterial pressure and heart rate were lower, in PVL rats. Dose-dependent contractile responses were observed for both norepinephrine (1 x 10(-8) - 3 x 10(-6) M) and vasopressin (3 x 10(-10) - 3 x 10(-8) M) in the tail artery of both groups. The contractile response to norepinephrine was significantly decreased in PVL rats compared with controls at all doses. The contractile response to vasopressin was significantly decreased in PVL rats at higher doses. After myo-[3H]inositol incorporation in tail artery, the levels of 3H-labelled phosphatidylinositols (cpm/mg) were similar between the two groups. Norepinephrine (10(-7) - 10(-5) M) and vasopressin (10(-10) - 10(-8) M) dose dependently stimulated the 3H-labelled inositol phosphate production in the tail artery of both PVL and sham-operated rats. However, the response was significantly lower in PVL rats. The results suggested that the attenuation of vascular contractile responses in portal hypertension was reflected in the phosphoinositide messenger system.

Study on the vascular reactivity and alpha 1-adrenoceptors of portal hypertensive rats.

1. Vascular hyporesponsiveness in portal hypertension has been demonstrated to various vasoconstrictors including noradrenaline (NA). The present study aimed to determine whether the attenuated vascular responsiveness to NA is due to a change in the affinity or the number of alpha 1-adrenoceptors. 2. Partial portal vein ligation (PVL) was performed in Sprague-Dawley rats to produce portal hypertension. Vascular responsiveness to NA was assayed in portal vein, mesenteric artery or tail artery. The affinity and number of alpha 1-adrenoceptors were determined by specific binding of [125I]-HEAT (2-beta-4-hydroxy-3-iodophenyethyl-aminomethyltetralone). 3. In the presence of yohimbine (10(-7) M, an alpha 2-adrenoceptor antagonist), propranolol (10(-6) M, a beta-adrenoceptor antagonist), and two catecholamine uptake inhibitors, desipramine (10(-7) M) and normetanephrine (10(-6) M), the maximum responses to NA were decreased in all three blood vessels of PVL rats: 45% decrease in portal vein, 25% in mesenteric artery and 18% in tail artery. 4. The EC50 values of NA and the pA2 values of prazosin, an alpha 1-adrenoceptor antagonist, in all three blood vessels were not significantly different between sham-operated and PVL rats. 5. The KD and Bmax values for specific binding of [125I]-HEAT or the Ki values for NA in the crude membrane preparations of either mesenteric artery or tail artery were also not significantly different between the two groups. 6. It is concluded that the vascular hyporesponsiveness to NA in the mesenteric artery or tail artery of PVL rats is not due to changes in the affinity or number of alpha 1-adrenoceptors.

Rapid assay of the monoamine content in small volumes of rat plasma.

A method for the simultaneous measurement of serotonin catecholamines, and their metabolites in rat plasma by ultrafiltration and microbore liquid chromatography with electrochemical detection (LC-ED) in small volumes is established. Prior to the LC assay, sixteen plasma ultrafiltrates are readily prepared within 30 min in the present study. The present method, applying a dual-electrode detection technique, provides an additional reliable assignment or measurement of peaks by identifying the peaks on the basis of their redox ratios. In addition, the important early-eluting peaks and interfering peaks are eliminated in the cathodic chromatogram resulting in a reliable measurement of norepinephrine, epinephrine, and 3,4-dihydroxyphenylacetic acid. Isocratic separation of serotonin, catecholamines, and their metabolites by a microbore column is achieved within 15 min. Hence, theoretically, over 90 analyses can be performed in a working day. The limit of detection (signal-to-noise ratio = 3) of this method is ca. 0.2-0.5 pg per injection for all analytes. The required volume of the plasma samples can be less than 100 microliters. Hence, the remainder of the plasma sample can be analysed for other substances. This rapid, simple, and sensitive method can thus be used as a research tool in the simultaneous measurement of rat plasma serotonin, catecholamines, and their metabolites.