A comparison of matrix resolution method, ratio spectra derivative spectrophotometry and HPLC method for the determination of thiamine HCl and pyridoxine HCl in pharmaceutical preparation

A comparison of two spectrophotometric methods and a HPLC method were described in this work for the analysis of pyridoxine hydrochloride and thiamine hydrochloride in a vitamin combination. In the first method, A₁¹ (1%, 1 cm) values of these two compounds were calculated using absorbances measured at 246.8 and 290.5 nm in zero-order spectra. The matrix was written for A₁¹ (1%, l cm) values and the concentration of both compounds were determined using ‘Matlab’ software. In the second method, the measurements in the derivative of the ratio spectra were made at 297.8 and 309.5 nm for pyridoxine hydrochloride and at 245.6 and 257.7 nm for thiamine hydrochloride. The calibration graphs were established in the range 8–40 μg/ml of both vitamins. In the HPLC method, the separation of these compounds was realized on a Nucleosil 100-5 C₁₈ column with 0.1 M (NH₄)₂C0₃–water–methanol (5:15:80 v/v) as the mobile phase. Results of spectrophotometric and HPLC procedures were compared.     

Tramadol encapsulated into polyhydroxybutyrate microspheres: in vitro release and epidural analgesic effect in rats

BACKGROUND: Controlled release techniques are used to increase the duration of action and decrease the toxicity of drugs. Any controlled release form of tramadol in spinal or epidural blocks has not been studied previously. Tramadol was encapsulated into polyhydroxybutyrate (PHB) microspheres and release kinetics was studied. The epidural analgesic effect of this solution in rats was also compared with free tramadol. METHODS: Controlled release of tramadol from PHB microspheres into 10 ml of phosphate buffer solution at pH 7.4 and 37 degrees C was studied in vitro. In vivo studies were performed in 40 rats. Epidural catheters were placed during general anaesthesia. Rats were randomly allocated into one of the four study groups to receive normal saline, 4 mg of tramadol, PHB microspheres without tramadol, or 4 mg of tramadol encapsulated into PHB microspheres. Analgesia was evaluated with tail flick tests performed at 52.5 +/- 0.5 degrees C before injection and at intervals up to 30 h after injection. Catalepsy and loss of corneal reflexes were considered as signs of supraspinal toxicity. RESULTS: In vitro drug release was observed for more than 6 days. Epidural analgesic effects of tramadol released from PHB microspheres were observed for 21 h, whereas an equal dose of free tramadol was effective for less than 5 h. No signs of toxicity were observed. CONCLUSION: Controlled release of tramadol from PHB microspheres is possible, and pain relief during epidural analgesia is prolonged by this drug formulation compared with free tramadol.     

Mediation of nitric oxide from photosensitive stores in the photorelaxation of the rabbit corpus cavernosum

Isolated rabbit corpus cavernosum relaxed in response to ultraviolet (UV) light (365 nm). The UV light-induced relaxation (photorelaxation) was diminished on repeated UV irradiation from 30.5+/-4.0% (the first photorelaxation) to 15.5+/-2.7% (the last photorelaxation). Hydroxocobolamine of 100 microM and hemoglobin (Hb) of 10 microM, which are nitric oxide (NO) scavengers, and 10 microM 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), a soluble guanylyl cyclase inhibitor, markedly reduced photorelaxation. However, 300 microM 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (carboxy-PTIO) failed to inhibit photorelaxation. NaNO(2) and N(G)-nitro-L-arginine (L-NA) but not 3-nitro-L-tyrosine (3-NT) were found to be photosensitive in that these compounds are photolysed to release NO, as demonstrated by use of an amperometric NO probe; NO signals produced by 500 microM NaNO(2), and 500 microM L-NA were 133.3+/-28.9 and 54.4+/-10.4 pA, respectively. Not 3-NT but the other compounds (all 200 microM) also enhanced photorelaxation of the cavernosal tissue. Based on these findings, the substance, which mediates photorelaxation, could be NO released from putative stores in the rabbit corpus cavernosum, and L-NA as well as NaNO(2) but not 3-NT produce NO under the influence of UV light.     

Atherogenic profile in preeclampsia

Atherosis is accepted to underlie the pathogenesis of preeclampsia, therefore we aimed to determine malonyldialdehyde (MDA) levels as a marker of lipid peroxidation, and lipoprotein(a) (Lp(a)), apolipoprotein A-1 (Apo A-1) and apolipoprotein B (Apo B) levels as a marker of atherogenic profile in preeclamptic and normal pregnant women. Twenty preeclamptic and 20 gestational-age matched normal pregnant patients were enrolled in the study, mean gestational ages for the preeclamptic and the control group were 33.9+/-1.4 and 35.5+/-0.7 weeks, respectively. Blood was withdrawn from the patients soon after diagnosis, and from the controls at their routine prenatal visits. MDA levels was significantly higher in preeclamptic patients (P=0.0003), but no difference was observed in Apo A-1 and Apo B and Lp(a) levels between the 2 groups. We consider that higher MDA was due to oxidative stress seen in preeclampsia, and similar Apo A-1 and Apo B and Lp(a) levels were due to lack of systemic atherosis.     

Slow Coronary Flow: Correlations with Myocardial Perfusion Tomography and Coronary Arteriography

A reduction in velocity in coronary artery contrast filling during coronary arteriography that is called slow coronary flow is one of the reasons of myocardial ischemia. Ischemia mechanism hasn't been understood. We evaluated coronary arteriographic and scintigraphic properties in patients with a slow flow pattern (SFP). The study included 60 patients who revealed SFP in their coronary arteriograms. The control group consisted of 50 patients with normal myocardial perfusion and normal coronary arteries in their coronary arteriograms. The Thrombolysis in Myocardial Infarction (TIMI) flow count method was used for the assessment of slow coronary flow. Single day rest-stress Technetium-99m hexakis-2-methoxy-isobutyl isonitrile (Tc-99m MIBI) myocardial perfusion tomography was performed to all study patients. Patients with SFP revealed both higher frame counts in native coronary arteries and higher average frame counts. In control patients, the average frame count was 26.4 ± 3.5 (LAD: 35.4 ± 3.3, LCx: 22.5 ± 4.5, RCA: 21.5 ± 2.8). In patients with SFP the average frame count was 64.40 ± 16.64 (LAD: 85.75 ± 24.39, LCx: 57.21 ± 15.25, RCA: 53 75 ± 17.81) (p < 0.001). Myocardial perfusion tomography showed ischemia in 17 patients (Group 1), while 43 patients in Group 2 revealed no perfusion defect. There were no statistically significant differences between Groups 1 and 2 in frame counts. In conclusion, no correlation was observed between the time needed to fill a native coronary artery and ischemia even if there is SFP.     

A Rare Asymptomatic Arteriovenous Fistula Between Right Renal Artery and Inferior Vena Cava Following Penetrating Trauma: A Case Report

A 20-year-old male patient was admitted to our outpatients clinics due to penetrating injury in the right lumbosacral region, occurred four months ago. In his routine examination, a continuous murmur was heard on the right lumbar region and angiographic examination was done. The angiography showed an arteriovenous (A-V) fistula between the right renal artery (RRA) and inferior vena cava (IVC). After this diagnosis, primer closure of the fistula was done surgically. After surgical repair, the murmur was lost and closure of the fistula was shown by postoperative angiography.     

Visual lateralization in the bottlenose dolphin (Tursiops truncatus): evidence for a population asymmetry?

A previous behavioural study with a single bottlenose dolphin had reported a right eye superiority in visual discrimination tasks, indicating a left hemisphere dominance for visual object processing. The presence of a functional asymmetry demonstrated with one individual shows that this function can be lateralized in this single animal, but cannot reveal if this represents a population asymmetry. Therefore, we conducted a series of visual discrimination experiments with three individuals of Tursiops truncatus under monocular conditions. The tested animals had to distinguish between simultaneously presented stimulus pairs of different patterns, whereby one stimulus was always defined to be correct. Additionally, the animals were observed for their free eye use during training and introduction of new items. The present data set revealed a right eye advantage (left hemisphere dominance) for all tested animals and a predominance of right eye use during daily activities. These results make it possible that bottlenose dolphins are lateralized for visual pattern discrimination at the level of a population asymmetry. Against the background of similar data in other vertebrates, a left hemisphere dominance for pattern discrimination points to the possibility that dolphins exploit local visual details instead of global configurational features to recognize and memorize visual stimuli.     

The architecture of an inhibitory sidepath within the avian tectofugal system

The tectofugal system dominates vision in most avian species. A key component of this pathway is the projection from the optic tectum onto the nucleus rotundus and the nucleus subpretectalis. Since subpretectalis has inhibitory projections onto rotundus, it constitutes a modulatory tectofugal sidepath to the tectorotundal system. We analyzed the connections and the immunocytochemical pattern of the subpretectalis in pigeons and show that it receives afferents from some tectal celltypes and from the nucleus pretectalis. Subpretectalis-neurons project non-topographically onto pretectalis and the rostrolateral rotundus. In addition, our immunocytochemical data make it likely that the cells of the subpretectalis receive glutamatergic and GABAergic input. These data provide evidence that the tectofugal sidepath over the subpretectalis could be involved in two major functions: The first is a modulation of attentional shifts from one eye to the other, while the second is a temporal fine-tuning of rotundal units.     

Age-related changes in hemispheric asymmetry depend on sex

A total of 92 participants, 50 younger (mean age 26.3 years) and 42 older (mean age 63.8 years), were tested for visual-field asymmetries. On a word-matching task, a right-visual-field (RVF) advantage increased with age, consistent with the theory that right-hemispheric function shows relatively greater decline with age than left-hemispheric function. On a figural-comparison task, a left-visual-field (LVF) advantage was marginally decreased with age in the men, but significantly increased in the women, probably because age-related changes in hormonal levels are more pronounced in women. This increase in LVF advantage is contrary to both the HAROLD theory that hemispheric asymmetry declines with age, and the theory of relative right-hemispheric decline.