Differential effects of intravenous magnesium on atrioventricular node conduction in supraventricular tachycardia

Evidence from noninvasive studies suggests magnesium has a differential effect on atrioventricular nodal (AVN) pathways. To further explore the electrophysiologic effects of intravenous magnesium sulfate (MgSO(4)) on supraventricular tachycardia, with particular reference to AVN conduction pathways, we studied 23 patients with supraventricular tachycardia at the time of electrophysiologic study. Tachycardia cycle length; AH, HV, and VA intervals; anterograde and retrograde Wenckebach thresholds; slow and fast pathway effective refractory periods (ERPs); accessory pathway ERP; right atrial and ventricular ERPs; blood pressure; and serum magnesium were evaluated before and after administration of MgSO(4) during sustained tachycardia. AVN reentry was induced in 14 patients and atrioventricular reentry was induced in 9; 1 of the latter had dual AVN physiology with tachycardia using the slow pathway. Serum magnesium level increased from 0.88 +/- 0.11 to 1.79 +/- 0.14 mmol/L (p <0.0001). Magnesium increased tachycardia cycle length to a greater extent in those with dual AVN physiology than those without: 340 +/- 54 to 370 +/- 57 ms versus 347 +/- 29 to 350 +/- 30 ms (p = 0.01). This was associated with greater increase in AH interval in those with dual AVN physiology than in those without: 241 +/- 59 to 270 +/- 60 ms versus 144 +/- 16 to 140 +/- 20 ms (p = 0.003). Presence of dual AVN physiology was more frequently associated with reversion to sinus rhythm: 5 of 15 versus 0 of 8 (p = 0.06). MgSO(4) did not alter other measured parameters. In conclusion, magnesium increases tachycardia cycle length and AH interval in patients with dual AVN physiology through a dominant effect on the slow AVN pathway.     

Chronic mesenteric ischemia and therapeutic paradigm of mesenteric revascularization

Chronic mesenteric ischemia is a life-threatening clinical problem resulting in death from inanition and/or bowel infarction, if left untreated, albeit low disease prevalence. Typical presentation is postprandial abdominal pain, severe weight loss, and altered bowel habit. Surgical revascularization of the superior mesenteric artery provides effective long-term treatment for chronic intestinal ischemia. Eleven patients underwent superior mesenteric artery revascularization, nine of them with open retrograde superior mesenteric artery bypass and two with angioplasty and stenting. All patients except one made a satisfactory recovery in this cohort. Major complication included one graft thrombosis leading to bowel ischemia and death. The rest all recovered weight in 3–6 months with a follow up period of 6 to 28 months. Two patients had recurrence of symptoms due to failing bypass requiring stenting for assisted primary patency. Superior mesenteric artery revascularization can be performed with minimal morbidity and mortality, providing excellent symptom relief and quality of life.     

Clinical evaluation of the fiber post and direct composite resin restoration for fixed single crowns on endodontically treated teeth

Background

The restoration of an endodontically treated fractured tooth has been a challenge for restorative dentists for decades. The performance of fiber posts when used in conjunction with direct composite resin restorations have been largely unreported. This study was conducted with the aim of evaluating the survival rate of endodontically treated teeth restored with adhesive bonded fiber reinforced resin posts and direct composite core with additional crown coverage.

Methods

Sixty patients who required endodontic treatment with post core crown were selected from outpatient department of Air Force Institute of Dental Sciences, Bangalore. Sixty-four teeth were endodontically treated and restored with fiber post and direct resin composite core restoration. Patients were evaluated immediately after restoration and reevaluated at the end of first, second and third months. After 3 months of clinical evaluation, if teeth were asymptomatic they were restored with complete coverage porcelain fused to metal restorations and evaluated immediately, and again reevaluated at the end of first, third, and sixth months.

Results

After 3 months of clinical evaluation, only two teeth exhibited periapical lesion with clinical symptoms and three teeth without any clinical symptoms. Five teeth exhibited slight marginal staining, three teeth showed partial loss of restoration, and two teeth exhibited complete loss of restoration with the fracture of the post. At the end of sixth month after restoration with full coverage crown, two teeth had dislodged restoration due to fracture of post and two teeth exhibited displacement of the post.

Conclusion

Fiber posts are the best alternative for restoration of fractured endodontically treated teeth. Fiber posts and direct composite resin core materials are strongly recommended for restoration of endodontically treated mutilated teeth among the dental establishments of Armed Forces.     

Nanocharacterization of liposomes for the encapsulation of water soluble compounds from Cordyceps sinensis CS1197 by a supercritical gas anti-solvent technique

Nano-liposomes were designed for the sustained release of water soluble compounds from C. sinensis CS1197 using a supercritical gas anti-solvent (SC-GAS) method at various pressures, temperatures and Tween 80 concentrations. The SC-GAS method was compared to the Bangham method of liposome production in terms of mean diameter, coefficient of uniformity (C_u), encapsulation efficiency, morphology, viscosity and actual energy required for liposome formation. Liposome production via the SC-GAS method under optimized formulation conditions, i.e., 180 bar; 50 °C; 0.75% Tween 80; and a depressurization rate of 25 bar min⁻¹, yielded nano-liposomes exhibiting the lowest C_u value (1.10 ± 0.012) with a mean diameter of 0.072 ± 0.002 μm and better encapsulation efficiencies of 75.48 ± 2.5, 74.9 ± 2.1 and 70.23 ± 2.9% for adenosine, cordycepin and polysaccharides, respectively. Nano-liposomes were characterized using FTIR, XRD, DSC and TGA techniques. The stability indices and viscosities of the prepared liposome suspensions indicated good stability of up to 2 months and near-Newtonian behavior. The in vitro release of CS1197 water soluble compounds exhibited biphasic and sustained release patterns.

Nano-liposomes were designed for the sustained release of water soluble compounds from C. sinensis CS1197 using a supercritical gas anti-solvent (SC-GAS) method at various pressures, temperatures and Tween 80 concentrations.     

The Relationship Between Life Course Factors,Parental Demographics,Dental Coping Beliefs and Its Influence on Adolescents Dental Visit: a Cross Sectional Study

Background

Oral Disease is a multifactorial one that includes behavioral and cultural components, and the severity of the disease depends on regularity of dental visits. The purpose of the study was to evaluate the relationship between parental demographics, life course factors, dental coping beliefs with therecent dental attendance among adolescents in Udupi Taluk.

Methods

Three hundred and fifty adolescents aged 16–19 years from four randomly selected schools in Udupi Taluk participated in this cross sectional study. Information was obtained regarding their parental demographics, their early life course, dental coping beliefs and recent dental attendance. Bivariate followed by multiple logistic regression analysis was performed to elicit variables which predict recent dental attendance.

Results

Out of the 324 adolescents who completed the questionnaire, 25.3% reported visiting a dentist within a period of one year. Childhood dental visit, childhood dental experience, housing, internal and external locus of control and self-efficacy were significantly associated with recent dental visit (p<0.05). Participants who lived in cement/brick houses were 4.3 times more likely to visit a dentist within one year compared to those living in hut/mud/combined houses (p<0.05). Adolescents with lower external (OR= 0.11, P<0.003) and low internal (OR=0.05, P<0.001) locus of control had lower odds of visiting a dentist within a year when compared with those having higher locus of control.

Conclusion

Childhood financial hardships, childhood dental visits and experiences and dental coping beliefs affect dental attendance pattern during adolescence. These factors should be considered while tailoring interventions to promote the oral health and dental attendance behaviors of adolescents.     

Enhanced photocatalytic and antibacterial activity of plasma-reduced silver nanoparticles

A non-thermal atmospheric pressure plasma jet has been used for the green synthesis of highly dispersed colloidal silver nanoparticles. The reducing species such as hydrogen radicals and hydrated electrons are identified, and the change in the solution pH is studied during AgNP formation. The structural properties and size of the plasma-reduced silver nanoparticles are characterized via X-ray diffraction, ultraviolet-visible spectroscopy, fluorescence spectroscopy and transmission electron microscopy. The size of the colloidal AgNPs is tuned by adjusting the initial concentration of AgNO₃. The effect of terephthalic acid, a hydroxyl radical scavenger, on the reduction of Ag⁺ ion is studied. The typical catalytic activity data indicate the better performance of the plasma-reduced colloidal Ag nanoparticles than that obtained from the chemical reduction method. The antibacterial activity of the plasma-reduced Ag nanoparticles also shows a better performance than that of the chemically reduced AgNPs, highlighting the potential of the plasma reduction approach for the synthesis of metal nanoparticles, which are stable even after 30 days without a stabilizing agent. Additionally, the effects of hydroxyl scavengers (isopropyl alcohol) and Fenton''s reagent (Fe²⁺ salt) on CV degradation are studied.

A non-thermal atmospheric pressure plasma jet has been used for the green synthesis of highly dispersed colloidal silver nanoparticles.     

Prevalence of migraine and response to sumatriptan in patients self-reporting tension/stress headache

OBJECTIVE: This study was conducted to evaluate the prevalence of migraine and its responsiveness to migraine-specific therapy in patients with self-reported tension-type headache. METHODS: Patients were adults (n = 423) consulting one of 54 North American study sites including primary care clinics, neurology clinics, and headache clinics. The study comprised an initial diagnosis phase to determine the headache diagnosis of patients entering the study with self-reported tension/stress headache, including that previously diagnosed by a health care provider. Patients reporting tension/stress headache were evaluated and diagnosed as having migraine with or without aura, probable migraine, tension-type headache, or another headache type. Exclusion criteria included prior diagnosis of migraine or probable migraine and the presence of headache for at least 15 days monthly during either of the 2 months before screening. The initial phase was followed by a randomized, double-blind treatment phase to evaluate the efficacy of sumatriptan 100 mg tablets for the treatment of a single migraine attack in those meeting International Headache Society (IHS) criteria for migraine during the diagnosis phase. RESULTS: Of 423 patients reporting tension/stress headache at study entry, 84% (n = 357) were diagnosed at the clinic visit as fulfilling IHS criteria for migraine without aura or migraine with aura, and 65% (n = 276) were diagnosed with migraine only (i.e., with no other concurrent headache diagnosis). Three hundred thirty-two (332) patients entered the double-blind treatment phase. Headache relief rates 2h post-dose, the primary efficacy endpoint, did not significantly differ between sumatriptan and placebo (p = 0.099). However, improvements were significantly (p < 0.05) greater with sumatriptan than placebo on several other headache-related efficacy measures. CONCLUSIONS: Migraine headache may go unrecognized in patients with self-reported tension headache. Among patients having self-reported tension headache and diagnosed with migraine during the study, response to acute treatment with sumatriptan was inconclusive. Improvement with sumatriptan versus placebo was observed for some measures and not for others. The results should be interpreted in the context of study limitations including use of patient self-reports to assess headache diagnosis and possible lack of representativeness arising from the predominantly white sample.     

Studies on protein and taurine in normal, senile and diabetic cataractous human lenses

An attempt has been made to explore the possible role of Taurine in cataractogenesis. Normal lenses were obtained from eye bank donors and cataractous lenses from patients who had undergone surgery for cataract extraction. Lenses were weighed and homogenised. Extraction, isolation and estimation of protein and taurine were carried out. It has been found that the lens wet weight increased progressively with the stage of maturation of cataract, i.e., from mature to hypermature which was significant and also with increase in age. Diabetic cataract group also showed an increase similar to that of senile cataract. Taurine and total protein decreases with different stages of maturation of cataract but not with age. It may be suggested that in the process of development of human senile cataract, there is (a) alteration in the structural integrity and permeability of lens membrane to protein and amino acids including taurine, (b) changes in the lens function including possible inhibition of proteins and amino acids (taurine) synthesis and transport across the cell membrane.