Determination of vitamin B6 in pharmaceutical formulations by flow injection-solid phase spectrophotometry

In this work, a new solid phase spectrophotometric method in association with flow injection analysis for Vitamin B6 (pyridoxine) determination has been developed with direct measurement of light-absorption in C18 material. In the developed method, successive passage of the complex, previously formed in the flowing stream, and eluent through the flow cell and continuous monitoring of the process provided the analytical information needed to determine pyridoxine. Pharmaceutical samples containing Vitamin B6 were previously dissolved in 0.1 mol l(-1) phosphate buffer solution (pH 7.5) and a sample volume of 235 microl was injected directly into carrier stream consisting of a mixture of methanol and 0.1 mol l(-1) phosphate buffer solution adjusted to pH 7.0 (1+1, v/v). The blue indophenol dye produced from the reaction between pyridoxine and N,N-diethyl-p-phenylenediamine after oxidation by potassium hexacyanoferrate(III) was quantitatively retained on C18 support and the spectrophotometric detection was performed simultaneously at 633 nm. The retained complex was quickly eluted from C18 material with the eluent stream consisting of a mixture of methanol and 0.01 mol l(-1) HCl (6+4, v/v). The results showed that the proposed method is simple, rapid and the analytical response is linear in the concentration range of 0.5-10 and 0.2-4 mg l(-1) using 235 and 860 microl of sample, respectively. The limits of detection are 0.15 and 0.060 mg l(-1) and the R.S.D. are 3.6% (at 2 mg l(-1) level) and 4.0% (at 1 mg l(-1) level) using sample volume of 235 and 860 microl, respectively. The system presented an analytical throughput of 15 determinations per hour when a sample volume of 235 microl was utilized. The procedure was successfully applied to the determination of Vitamin B6 in pharmaceutical formulations containing vitamins of B group and others active principles such as Vitamin C and minerals.     

Plasmodium falciparum histidine-rich protein II binds to actin,phosphatidylinositol 4,5-bisphosphate and erythrocyte ghosts in a pH-dependent manner and undergoes coil-to-helix transitions in anionic micelles

The recombinant histidine-rich protein II (HRPII) from Plasmodium falciparum was shown to bind actin and phosphatidylinositol 4,5-bisphosphate (PIP(2)) in vitro in a pH-dependent manner, very similar to hisactophilin, an actin-binding protein from ameba. Binding of HRPII to actin and PIP(2) occurred at pH 6.0 and 6.5, but not above pH 7.0. Circular dichroism (CD) spectroscopy confirmed that HRPII interacts with actin at pH below 7.0, as judged by the changes induced in the secondary structure of the HRPII/actin mixture. Further CD analysis demonstrated that HRPII adopts a predominantly alpha-helical conformation with anionic micelles of PIP(2) and SDS, but not with neutral micelles of phosphatidylcholine (PC), a feature that is common to many actin-binding proteins involved in cytoskeleton remodeling. Similarly to hisactophilin, a GFP-HRPII fusion protein shuttled from the cytoplasm to the nucleus of HeLa cells as the cellular pH was lowered from 8.0 to 6.0. HeLa cells transfected with the HRPII gene showed increased levels of histidine-rich proteins (HRPs) in the soluble cell fraction at pH 8.0. At pH 6.0, however, HRPs were detected mainly in the insoluble cell fraction. Interestingly, we found that HRPII binds to human erythrocyte membranes at pH 6.0 and 6.5 but not at pH above 7.0. Our results point to remarkable similarities between HRPII, hisactophilin, and actin-binding proteins. Possible roles of the HRPII during Plasmodium infection are discussed in the light of these findings.     

The transfer point is a novel measure of embryo placement

OBJECTIVE: To study the relationship between IVF-ET pregnancy outcomes and measures of embryo placement. DESIGN: Case-control study. SETTING: Tertiary care center. PATIENT(S): Twenty-three patients who underwent two ultrasonography-guided ETs, of which one resulted in a clinical pregnancy and the other did not. MAIN OUTCOME MEASURES: Point of embryo placement normalized to the endometrial cavity length (the transfer point), distance from the point of embryo placement to the uterine fundus, time required for ET, contact with the uterine fundus, and evidence of trauma. Videotaped ETs were quantitatively analyzed. RESULT(S): From February 1, 2000, to March 31, 2001, videotaped ETs from 23 pairs of pregnant and nonpregnant cycles were identified. Embryo placement was more shallow in pregnancy cycles than in nonpregnancy cycles. The groups did not differ in the absolute distance of embryo placement to the fundus, ovarian stimulation, or other features of the ET. CONCLUSION(S): The transfer point may serve as a better marker of embryo position than does the absolute distance to the uterine fundus.     

Blastomycosis of the vocal folds with life-threatening upper airway obstruction: a case report

Blastomycosis is a chronic fungal disease that primarily affects the lower respiratory tract. The acute inflammatory phase of the primary pulmonary infection is characterized by a lymphohematogenous spread to extrapulmonary sites, especially the skin. The presence of disseminated infection with Blastomyces dermatitidis in the larynx is unusual. In areas of the United States where this fungus is endemic, failure to consider laryngeal involvement might lead to inappropriate therapy and thus worsening inflammation and airway compromise.     

Dual-setting calcium phosphate cement modified with ammonium polyacrylate

alpha-Tricalcium phosphate bone cement, as formerly designed and developed by Driessens et al., consists of a powder composed by alpha-tricalcium phosphate (alpha-TCP) and hydroxyapatite (HA) seeds, and an aqueous solution of Na2HPO4 as mixing liquid. After mixing powder and liquid, alpha-TCP dissolves into the liquid and calcium deficient hydroxyapatite (CDHA), more insoluble than the former, precipitates as an entanglement of crystals, which causes the setting and hardening of the cement. alpha-TCP bone cement offers several advantages in comparison to calcium phosphate bioceramics and acrylic bone cements as bone graft and repairing material, like perfect adaptability to the defect size and shape, osteotransductibility, and absence of thermal effect during setting. The main handicap is its low mechanical strength. Therefore, approaching its mechanical strength to that of human bone could considerably extend its applications. In the present work, an in situ polymerization system based on acrylamide (AA) and ammonium polyacrylate (PA) as liquid reducer was added to alpha-TCP cement to increase its mechanical strength. The results showed that the addition of 20 wt% of acrylamide and 1 wt% AP to the liquid increased the compressive and tensile strength of alpha-TCP bone cement by 149 and 69% (55 and 21 MPa), respectively. The improvement in mechanical strength seems to be caused by a decrease of porosity and the reinforcing effect of a polyacrylamide network coexisting with the entanglement of CDHA crystals. The studied additives do not affect the nature of the final product of the setting reaction, CDHA, but promote the reduction of its crystal size.     

A model for ammonia poisoning in cattle

The intravenous infusion of ammonium chloride was used to induce ammonia (NH3) poisoning in cattle. A 1.5 M ammonium chloride solution, buffered to pH 7.0, was infused at 400 mL/h until a convulsive episode occurred and therapy was initiated. Convulsions occurred with 200 to 1200 mL of ammonium solution. The clinical picture and metabolic effects were similar to the natural poisoning; no side effected occurred. The hypermmoniemia caused hyperglycemia, hyperlactemia, hyperkalemia and Intense metabolic acidosis. After treatment there was a sharp decrease in plasma NH3. Within 110 min all steers stood and recovered appetites. The induction of NH3 poisoning in cattle with ammonium chloride offers many advantages over the administration of high po doses of urea.     

Microbiological quality of drinking water of urban and rural communities,Brazil

OBJECTIVE: To evaluate the microbiological quality of treated and untreated water samples came from urban and rural communities and to examine the relationship between coliforms occurrence and average water temperature, and a comparison of the rainfall levels. METHODS: A sample of 3,073 untreated and treated (chlorinated) water from taps (1,594), reservoir used to store treated water (1,033), spring water (96) and private well (350) collected for routine testing between 1996 and 1999 was analyzed by the multiple dilution tube methods used to detect the most probable number of total and fecal coliforms. These samples were obtained in the region of Maring , state of Paran , Brazil. RESULTS: The highest numbers water samples contaminated by TC (83%) and FC (48%) were found in the untreated water. TC and FC in samples taken from reservoirs used to store treated water was higher than that from taps midway along distribution lines. Among the treated water samples examined, coliform bacteria were found in 171 of the 1,033 sampling reservoirs. CONCLUSIONS: Insufficient treatment or regrowth is suggested by the observation that more than 17% of these treated potable water contained coliform. TC and FC positive samples appear to be similar and seasonally influenced in treated water. Two different periods must be considered for the occurrence of both TC and FC positive samples: (i) a warm-weather period (September-March) with high percentage of contaminated samples; and (ii) cold-weather period (April-August) were they are lower. Both TC and TF positive samples declined with the decreased of water temperature.     

c-Myc overexpression sensitises colon cancer cells to camptothecin-induced apoptosis

The proto-oncogene c-Myc is overexpressed in 70% of colorectal tumours and can modulate proliferation and apoptosis after cytotoxic insult. Using an isogenic cell system, we demonstrate that c-Myc overexpression in colon carcinoma LoVo cells resulted in sensitisation to camptothecin-induced apoptosis, thus identifying c-Myc as a potential marker predicting response of colorectal tumour cells to camptothecin. Both camptothecin exposure and c-Myc overexpression in LoVo cells resulted in elevation of p53 protein levels, suggesting a role of p53 in the c-Myc-imposed sensitisation to the apoptotic effects of camptothecin. This was confirmed by the ability of PFT-alpha, a specific inhibitor of p53, to attenuate camptothecin-induced apoptosis. p53 can induce the expression of p21(Waf1/Cip1), an antiproliferative protein that can facilitate DNA repair and drug resistance. Importantly, although camptothecin treatment markedly increased p21(Waf1/Cip1) levels in parental LoVo cells, this effect was abrogated in c-Myc-overexpressing derivatives. Targeted inactivation of p21(Waf1/Cip1) in HCT116 colon cancer cells resulted in significantly increased levels of apoptosis following treatment with camptothecin, demonstrating the importance of p21(Waf1/Cip1) in the response to this agent. Finally, cDNA microarray analysis was used to identify genes that are modulated in expression by c-Myc upregulation that could serve as additional markers predicting response to camptothecin. Thirty-four sequences were altered in expression over four-fold in two isogenic c-Myc-overexpressing clones compared to parental LoVo cells. Moreover, the expression of 10 of these genes was confirmed to be significantly correlated with response to camptothecin in a panel of 30 colorectal cancer cell lines.