Effects of Russell's viper venom fractions on systemic and renal hemodynamics.

Changes in systemic and renal hemodynamics induced by Russell's viper venom are well established. The component of the venom responsible for hemodynamic alteration has not been identified. By Sephadex column chromatography five fractions of Russell's viper (Daboia russellii siamensis) venom were isolated. Each venom fraction consisted of phospholipase A2, proteolytic enzyme, phosphomonoesterase, phosphodiesterase, arginine ester hydrolase and hyaluronidase of varying activities. Hemodynamic effects of each venom fraction including mean arterial pressure, cardiac output, systemic and renal vascular resistance, renal blood flow and glomerular filtration rate were studied in five groups of dogs; each group had four dogs. Minimal hemodynamic changes were observed in dogs receiving venom fraction I. Increased renal vascular resistance with diminution of renal blood flow and glomerular filtration rate was observed in dogs receiving venom fractions II, III, IV and V. A markedly increased renal vascular resistance with maximal decrease in renal blood flow and glomerular filtration rate was caused by fraction III of the venom with highest PLA2 and proteolytic enzyme activities. However, renal hemodynamic changes appeared to correlate better with proteolytic enzyme activity than PLA2 activity. The findings suggested the proteolytic enzyme as an important determinant of hemodynamic alteration. Fractional excretion of Na was increased in dogs injected with venom fraction IV, and is presumed to be due to the inhibition of tubular reabsorption of Na by a natriuretic factor in this venom fraction.     

A pilot experiment for production of Malayan krait antivenom: immunization of rabbits with Bungarus candidus venom

Immunization with Bungarus candidus venom was performed in four rabbits at high dose (initial dose, 75 microg/kg) and low dose (initial dose, 50 microg/kg). Each dose group consisted of two rabbits; one rabbit received the venom subcutaneously (s.c.) and the other intradermally (i.d.). The venom was injected as emulsified solutions with the same volume of Freund's complete adjuvant until the 4th immunization, thereafter as plain solutions. By stepwise increments of the immunizing dose, the higher dose group received a dose of 200 microg/kg and the lower dose group 150 microg/kg after the 5th immunization, respectively. Thereafter, seven additional immunizations were performed within six months. All rabbits were sacrificed two weeks after the last immunization (12th). Antilethal activity of the immunized antisera thus obtained was determined not only with the homologous venom but also with two heterologous venoms from Bungarus fasciatus and Bungarus flaviceps. Immunodiffusion analysis was also performed with these venoms. The results obtained in this pilot trial provided useful information for production of Malayan krait antivenom at Queen Saovabha Memorial Institute.     

Diabetes and cardiovascular risk factor controls in Thai type 2 diabetes with no history of cardiovascular complications; situation and compliance to diabetes management guideline in Thailand

BackgroundCardiovascular complication is one of the most important issues causing morbidity and death in diabetic patients. Primary prevention is a key to prevent this complication.AimsThe objective was to study the situations of diabetes and cardiovascular risk factor controls in Thai type 2 diabetic patients who had no history of cardiovascular complication at a university hospital in Thailand after the Thai diabetes management guideline was recently launched.MethodsThe study was a cross-sectional survey in type 2 diabetes patients with no history of cardiovascular disease. Seven hundred and fourteen patients were enrolled in the study and 54.3% were females. The data were collected retrospectively from out-patient medical records and an electronic data base for the patients who were followed up at the hospital during January–December 2010. The most recent laboratory values were utilized in the analysis.Results70%–90% of all patients were checked for HbA1c and lipid profiles (LDL-C, total cholesterol, triglycerides) at least once a year. It was observed that only 28% of the patients had HbA1c < 6.5%. Furthermore, the percentages of the patients who had blood pressure < 130/80 mmHg, and who had LDL-C < 100 mg/dL were 28% and 41%, respectively.ConclusionEven though the practice guideline has been launched since 2008, diabetes, hypertension and dyslipidemia were still poorly controlled. Further study is recommended to identify factors influencing these outcomes as well as the policy of diabetic care in Thailand is needed to be seriously implemented.     

The effect of tooth-preparation cleansing protocol on the bond strength of self-adhesive resin cement to dentin contaminated with a hemostatic agent

This study evaluated the effect of tooth-preparation cleansing protocols on the bond strength of a self-adhesive resin cement to dentin contaminated with two different types of hemostatic agents. The occlusal surface of extracted third molars was flattened to expose the dentin surface and prepared for a full crown. Acrylic temporary crowns were fabricated and placed using temporary cement. The specimens were stored at 100% relative humidity for seven days. Following removal of the temporary crowns, the specimens were surface debrided using aluminum oxide abrasion with a particle size of 27 μm at 40 psi. The specimens were randomly assigned to three groups, according to the hemostatic agents: Group I–an agent containing aluminum chloride was applied to the tooth surface; Group II–an agent containing ferric sulfate was applied to the tooth surface and Group III–uncontaminated (control). The contaminated specimens were then further subdivided into three subgroups (A–C; n=12): Group A–tooth surface cleansing with water spray; Group B–tooth surface cleansing with phosphoric acid etch and Group C–tooth surface cleansing with aluminum oxide abrasion with a particle size of 27 μm at 40 psi. Ceramic blocks were treated with a 9.5% hydrofluoric acid-etch and silanized prior to being cemented with self-adhesive resin luting agent (RelyX Unicem) to the prepared dentin. The shear bond strength was determined at a crosshead speed of 0.5 mm/minute. The data were analyzed with two-way ANOVA, followed by the Duncan multiple range test, to determine any significant differences between the testing groups. The microstructure morphology of the tooth surface was evaluated using SEM analysis. The results revealed that there was a significant difference between the bond strength of the control and the contaminated testing groups (p<0.05). A tooth preparation cleansing protocol using particle abrasion with low-pressure aluminum oxide particles provided a significant improvement in bond strength to contaminated dentin, while rinsing with water spray resulted in the lowest mean bond strength of the self-adhesive resin cement to dentin (p<0.05).     

A Biochemical and Pharmacological Characterization of Phospholipase A2 and Metalloproteinase Fractions from Eastern Russell’s Viper (Daboia siamensis) Venom: Two Major Components Associated with Acute Kidney Injury

Acute kidney injury (AKI) following Eastern Russell’s viper (Daboia siamensis) envenoming is a significant symptom in systemically envenomed victims. A number of venom components have been identified as causing the nephrotoxicity which leads to AKI. However, the precise mechanism of nephrotoxicity caused by these toxins is still unclear. In the present study, we purified two proteins from D. siamensis venom, namely RvPLA₂ and RvMP. Protein identification using LCMS/MS confirmed the identity of RvPLA₂ to be snake venom phospholipase A₂ (SVPLA₂) from Thai D. siamensis venom, whereas RvMP exhibited the presence of a factor X activator with two subunits. In vitro and in vivo pharmacological studies demonstrated myotoxicity and histopathological changes of kidney, heart, and spleen. RvPLA₂ (3–10 µg/mL) caused inhibition of direct twitches of the chick biventer cervicis muscle preparation. After administration of RvPLA₂ or RvMP (300 µg/kg, i.p.) for 24 h, diffuse glomerular congestion and tubular injury with minor loss of brush border were detected in envenomed mice. RvPLA₂ and RvMP (300 µg/kg; i.p.) also induced congestion and tissue inflammation of heart muscle as well as diffuse congestion of mouse spleen. This study showed the significant roles of PLA₂ and SVMP in snake bite envenoming caused by Thai D. siamensis and their similarities with observed clinical manifestations in envenomed victims. This study also indicated that there is a need to reevaluate the current treatment strategies for Thai D. siamensis envenoming, given the potential for irreversible nephrotoxicity.     

Prevalence and characteristics of metabolic syndrome in South‐East Asian psoriatic patients: A case–control study

The prevalence of metabolic syndrome in Asian psoriatic patients compared with that of the general population shows variable results. This study aimed to examine the association between psoriasis and metabolic syndrome in a Thai population. This case–control study included 199 psoriatic patients and 199 controls matched for sex and age from the general Thai population. There were 111 men (55.8%) and 88 women (44.2%) in both the psoriatic and control groups. The mean age (± standard deviation) of both groups was 50.04 ± 13.81 and 49.96 ± 14.39 years (P = 0.91), respectively. The majority of psoriatic cases (82.9%) were of plaque type. The prevalence of metabolic syndrome was significantly higher in psoriatic patients than in the general population at 49.25% versus 30.65%. After controlling for age, sex, smoking and alcohol drinking the odds ratio was 2.25 (P < 0.0001). The metabolic components which were significantly higher in the cases than controls included hyperglycemia, high blood pressure (HBP) and abdominal obesity. No statistically significant difference was found between the cases and controls regarding prevalence of obesity, hypertriglyceridemia and low high‐density lipoprotein cholesterol. Thai psoriatic patients had a higher prevalence of metabolic syndrome than the general population. In conclusion, the prevalence of HBP, hyperglycemia and abdominal obesity was significantly higher in cases than in controls.     

Insecticide resistance in bedbugs in Thailand and laboratory evaluation of insecticides for the control of Cimex hemipterus and Cimex lectularius (Hemiptera: Cimicidae)

Bedbugs are found in many countries around the world, and in some regions they are resistant to numerous insecticides. This study surveyed bedbugs in Thailand and determined their resistance to insecticides. The surveys were carried out in six provinces that attract large numbers of foreign tourists: Bangkok, Chonburi, Chiang Mai, Ubon Ratchathani, Phuket, and Krabi. Bedbugs were collected from hotels and colonized in the laboratory to evaluate their resistance to insecticides. Cimex hemipterus (F.) was found in some hotels in Bangkok, Chonburi, Phuket, and Krabi, whereas Cimex lectularius L. was found only in hotels in Chiang Mai. No bedbugs were found in Ubon Ratchathani. The colonized bedbugs showed resistance to groups of insecticides, including organochlorines (dichlorodiphenyl trichloroethane, dieldrin), carbamates (bendiocarb, propoxur), organophosphates (malathion, fenitrothion), and pyrethroids (cyfluthrin, deltamethrin, permethrin, lambda-cyhalothrin, etofenprox) in tests using World Health Organization insecticide-impregnated papers. The new insecticides imidacloprid (neonicotinoid group), chlorfenapyr (pyrrole group), and fipronil (phenylpyrazole group) were effective against the bedbugs; however, organophosphate (diazinon), carbamates (fenobucarb, propoxur), and pyrethroids (bifenthrin, cypermethrin, esfenvalerate, etofenprox) were ineffective. Aerosols containing various pyrethroid insecticides with two to four different active ingredients were effective against the bedbugs. The results obtained from this study suggested that both species of bedbugs in Thailand have developed marked resistance to various groups of insecticides, especially those in the pyrethroid group, which are the most common insecticides used for pest control. Therefore, an integrated pest management should be implemented for managing bedbugs in Thailand.     

The effects of tooth preparation cleansing protocols on the bond strength of self-adhesive resin luting cement to contaminated dentin

This in vitro study evaluated the bond strength of a self-adhesive luting cement after using four different techniques to remove surface contamination on dentin. Extracted human molars were flattened to expose the dentin surface and prepared for full crown preparation. Acrylic temporary crowns were fabricated and placed using temporary cement. The specimens were stored at room temperature with 100% relative humidity for seven days. Following removal of the temporary crowns, the specimens were randomly divided into four groups, and excess provisional cement was removed with (1) a hand instrument (excavator), (2) prophy with a mixture of flour pumice and water (3) aluminous oxide abrasion with a particle size of 27 microm at 40 psi and (4) aluminous oxide abrasion with a particle size of 50 microm at 40 psi. The microstructure morphology of the tooth surface was evaluated and residual materials were detected using SEM and EDS analysis of randomly selected specimens. The ceramics were treated with 9.5% hydrofluoric acid-etch and silanized to the prepared dentin prior to cementing with self-adhesive resin cement (RelyX Unicem, 3M ESPE). The shear bond strength was determined at a crosshead speed of 0.5 mm/minute. The results were analyzed with one-way ANOVA, followed by Tukey's test. Particle abrasion treatment of dentin with an aluminous oxide particle provided the highest values of bond strength, while hand instrument excavation was the lowest (p < 0.05). Aluminous oxide particle size did not significantly influence the bond strength at 40 psi. The use of low pressure and small particle abrasion treated dentin as a mechanical cleansing protocol prior to definitive cementation increased the bond strength of self-adhesive resin-luting cement to dentin following eugenol-containing temporary cement.