Histaminergic drugs in the rat caudate nucleus: effects on learned helplessness.

The effect of pharmacological manipulation of histaminergic receptors in the caudate nucleus (CN) has been examined in rats previously submitted to inescapable electric shock to produce learned helplessness (LH). Histamine H1 agonist 2-tiazolylethyl amine (TEA) microinjection produced protective effects, preventing the activity and cognitive loss typical in LH. Injection of the H1 antagonist astemizole (AZ) produced effects symmetrical to those produced by TEA, further reducing activity and impairing cognitive functions. The histamine H2 agonist 4-methyl-histamine (4MH) produced a shift on the side preference for rotation that interfered in the learning tests and obscured the effects of this drug on LH. Injection of the H2 antagonist cymetidine (CYM) caused LH-like effects in control animals. Thus, brain histamine seems to play a relevant role in the control of motor and cognitive functions of the CN.

Thin-layer chromatographic determination of catecholamines, 5-hydroxytryptamine, and their metabolites in biological samples: a review.

A review of methodology for separation, detection, and quantitative determination of catecholamines, 5-hydroxytryptamine, and their acidic metabolites in biological tissue and fluids by thin-layer chromatography is presented. Selected procedures, including fluorometric scanning densitometry for catecholamine acetyl derivatives and color scanning densitometry for acids, are described.

Asian venous thromboembolism guidelines: prevention of venous thromboembolism.

Venous thromboembolism (VTE) prophylaxis is under-utilized in Asia because of the misconception that its incidence is lower in Asians as compared to the Caucasians. The available data on VTE in Asia is limited due to the lack of well-designed multicenter randomized controlled trials as well as non-standardized research designs, making data comparison difficult. Emerging data indicates that the VTE incidence is not low in Asia, and is comparable to that reported in the Western literature in some instances. There is also a trend towards increasing incidence of VTE, as demonstrated by a number of hospital-based studies in Asia. This could be attributed to lifestyle changes, ageing population, increasing awareness of VTE and wider availability of Duplex ultrasound. The risk of VTE in hospitalized patients remain the same in Asians and Caucasians, even though there may be factors that are inherent to patients in Asia that influence the slight variation in incidence. The utilization rate of VTE prophylaxis remains suboptimal in Asia. The Asian Venous Thrombosis Forum (AVTF) comprises participants from various countries such as China, Hong Kong, India, Indonesia, Korea, Malaysia, Philippines, Singapore, Taiwan, Thailand and experts from Australia and Europe. The forum evaluated the available data on VTE from the Asian region and formulated guidelines tailored to meet the needs of the region. We recommend that serious considerations are given to VTE prophylaxis especially in the at-risk group and a formal hospital policy be established to facilitate the implementation. On admission to the hospital, we recommend assessing the patients for both VTE and bleeding risk. We recommend mechanical prophylaxis for patients at increased risk of bleeding and utilizing it as an adjunctive measure in combination with pharmacological prophylaxis in patients with high risk of VTE. For patients undergoing general or gynecological surgery and with moderate risk for VTE, we recommend prophylaxis with one of the following: low dose unfractionated heparin (LDUH), low molecular weight heparin (LMWH), fondaparinux or intermittent pneumatic compression (IPC). For the same group of patients at high risk of VTE, we recommend pharmacological or combination of pharmacological and mechanical prophylaxis. For patients undergoing major orthopedic surgeries like total hip replacement, total knee replacement and proximal hip fracture surgery, we recommend using one of the following: LMWH, fondaparinux, rivaroxaban, apixaban, edoxaban, dabigatran, warfarin or aspirin with IPC. For patients admitted to the hospital with acute medical illness and has moderate risk of VTE, we recommend prophylaxis with LDUH, LMWH or Fondaparinux. For the same group at high risk of VTE, we recommend combination of pharmacological and mechanical prophylaxis.

Thin-layer chromatographic determination of catecholamines in rat plasma.

A TLC method for the quantitative determination of epinephrine, norepinephrine and dopamine in rat plasma is described. After deprotenization, catecholamines were adsorbed on acid-alumina and acetylated. The acetyl derivatives were extracted using a C18 minicolumn, resolved on HPTLC plates and quantitated by fluorescence densitometry at 415 nm, using isoprenaline as internal standard.

Thin-layer chromatographic determination of brain catecholamines and 5-hydroxytryptamine.

A simple and sensitive (up to nanogram level) method to determine norepinephrine, serotonin and dopamine in rat brain is described. The amines are acetylated and the derivatives are resolved by thin layer chromatography (TLC) on silica high performance thin layer chromatography (HPLC) plates. Quantification is achieved by fluorescence densitometry at 415 nm excitation wavelength.

Simultaneous determination of vanillylmandelic, homovanillic and 5-hydroxyindoleacetic acids in human urine by thin layer chromatography.

A TLC method for the simultaneous analysis of vanillylmandelic, homovanillic and 5-hydroxyindole-3-acetic acids in urine is described. The sample is cleaned up through a cyano minicolumn and extracted with diethyl ether. The acids are resolved by high-performance TLC, visualized by Folin Ciocalteau reagent and quantificated by densitometry at 600 nm with beta-(4-hydroxy-3-phenyl) acetic acid as the internal standard.

A simple thin-layer chromatographic method for the analysis of buprenorphine in urine.

A simple and sensitive (at the ng/mL level) method for buprenorphine assay in urine is described. Buprenorphine is extracted by a C18 cartridge, derivatized with dansyl chloride, resolved by a uni-dimensional, two developing mobile phase high-performance thin layer chromatography system and quantified by fluorescence densitometry at 340 nm.

A simple method for plasma cannabinoid separation and quantification.

A sensitive (up to nanogram level) method for resolving a cannabinoid mixture in plasma is described. Cannabinoids were extracted with a C-18 Sep Pak cartridge and derivatized with dansylchloride. Then the derivatives were resolved on thin layer HPTLC silica plates which were developed and quantified by fluorescence densitometry at 340 nm.