Validated spectrophotometric determination of maduramicin ammonium using three charge transfer complexation reactions.

Direct spectrophotometric determination of Maduramicin ammonium (MAD) represents an analytical challenge since it is a weak UV-absorbing and lacking a strong chromophore. This work represents the first spectrophotometric determination of MAD as no direct spectrophotometric or colorimetric determination methods for MAD are available in the literature. The present study illustrates the development of three simple, rapid and inexpensive colorimetric methods for the routine quality control analysis of MAD based on the formation of colored charge transfer complexes with three electron acceptors namely p-chloranilic acid (p-CA), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and picric acid (PA). The color products of MAD with p-CA, DDQ and PA were measured at 519, 588 and 405nm respectively. The proposed methods were validated in terms of linearity, ranges, precision, accuracy, robustness and limits of detection and quantification. MAD was effectively determined over concentration ranges of 100-1000, 25-250 and 30-150µg/mL using p-CA, DDQ and PA, respectively with good linearity as shown by the values of correlation coefficients not less than 0.9991. The developed methods were successfully implemented in the assay of MAD powder pharmaceutical formulation for veterinary use.

Geology of the InSight landing site on Mars.

The Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) spacecraft landed successfully on Mars and imaged the surface to characterize the surficial geology. Here we report on the geology and subsurface structure of the landing site to aid in situ geophysical investigations. InSight landed in a degraded impact crater in Elysium Planitia on a smooth sandy, granule- and pebble-rich surface with few rocks. Superposed impact craters are common and eolian bedforms are sparse. During landing, pulsed retrorockets modified the surface to reveal a near surface stratigraphy of surficial dust, over thin unconsolidated sand, underlain by a variable thickness duricrust, with poorly sorted, unconsolidated sand with rocks beneath. Impact, eolian, and mass wasting processes have dominantly modified the surface. Surface observations are consistent with expectations made from remote sensing data prior to landing indicating a surface composed of an impact-fragmented regolith overlying basaltic lava flows.

Validated spectrophotometric and chromatographic methods for analysis of the recently approved hepatitis C antiviral combination ledipasvir and sofosbuvir.

This work describes five simple and reliable spectrophotometric and chromatographic methods for analysis of hepatitis C antiviral binary mixture of ledipasvir (LPV) and sofosbuvir (SBV). Method I is based on the use of Amax and derivative spectrophotometry with the zero-crossing technique where LPV was determined using its Amax and 1D amplitudes at 324 and 338nm respectively, while SBV was determined by measuring the 1D amplitudes at 276nm. Method II involves the application of the ratio spectra derivative spectrophotometry. For LPV, 12µg/mL SBV was used as divisor and the 1DD amplitudes at 239.8nm were plotted against LPV concentrations; while by using 10µg/mL LPV, the amplitudes at 279.2nm were found proportional to SBV concentrations. Method III depends on ratio-difference measurement where the peak to trough amplitudes between 229.2 and 268.4nm were measured and correlated to LPV concentration. Similarly, the amplitudes between 268.6 and 229.2nm in the SBV ratio spectra were recorded. For method IV, the two compounds were separated using HPTLC sheets of silica gel and a mobile phase composed of chloroform-methanol (94:6) followed by densitometric measurement of LPV and SBV spots at 331 and 267nm respectively. Method V depends on HPLC-DAD. Effective chromatographic separation was achieved using Thermohypersil C8 column (4.6×250mm, 5µm) with a mobile phase consisting of 0.01M sodium dihydrogen phosphate (pH 2.5) and methanol (20:80) at a flow rate 1.2mL/min and detection at 332 and 262nm for LPV and SBV respectively. Analytical performance of the developed methods was validated according to the ICH guidelines with respect to linearity, ranges, precision, accuracy, detection and quantification limits. The validated methods were successfully applied to the simultaneous analysis of LPV and SBV in mixtures of different proportions and their combined tablet dosage form.

Validated stability-indicating HPLC-DAD method for determination of the recently approved hepatitis C antiviral agent daclatasvir.

A comprehensive stability indicating HPLC with diode array detection method was developed for the determination of the recently approved antiviral drug daclatasvir dihydrochloride (DCV) which is used for the treatment of chronic Hepatitis C Virus (HCV) genotype 3 infection. Effective chromatographic separation was achieved using Waters C8 column (4.6×250mm, 5µm particle size) with isocratic elution of the mobile phase composed of mixed phosphate buffer pH 2.5 and acetonitrile in the ratio of 75:25 (by volume). The mobile phase was pumped at a flow rate of 1.2mL/min, and quantification of DCV was based on measuring its peak areas at 306nm. DCV eluted at retention time 5.4min. Analytical performance of the proposed HPLC procedure was thoroughly validated with respect to system suitability, linearity, range, precision, accuracy, specificity, robustness, detection and quantification limits. The linearity range was 0.6-60µg/mL with correlation coefficient>0.99999. The drug was subjected to forced degradation conditions of neutral, acidic and alkaline hydrolysis, oxidation and thermal degradation. The proposed method proved to be stability-indicating by resolution of the drug from its forced-degradation products. The validated HPLC method was successfully applied to analysis of the cited drug in its tablets.

Investigation into the toxicological effects of Catha edulis leaves: a short term study in animals.

In this study the short term (3 months) toxicological effects of varying levels of Catha edulis leaves were examined on the plasma concentration of liver enzymes and the histopathology of tissue sections of various organs including the liver, kidneys, spleen and testis. Both the biochemical and histopathological data demonstrated, initial signs of Catha edulis toxicity. Our results show a significant increase in plasma levels of alkaline phosphatase (ALP) and alanine aminotransferase (ALT) with all levels of Catha edulis leaves tested and throughout the treatment period. The increase of ALP was more prominent than that of ALT. The plasma levels of aspartate aminotransferase (AST) were only moderately increased at the higher dose (30%) in the later stages of treatment. In addition, a time-dependent gradual increase in indirect bilirubin with a concomitant decrease in direct bilirubin levels was observed with the 30% Catha edulis with no signs of haemolysis. The histopathology of tissue sections of the liver displayed evidence of congestion of the central liver veins as well as acute hepatocellular degenerative and regenerative activities in the tissue sections obtained from animals treated with both 20% and 30% Catha edulis. Similarly, histopathological examination of the tissue sections of the kidneys showed some lesions, and the degree of the lesion increased as the dose of Catha edulis leaves increased including: the presence of fat droplets particularly seen in the upper cortical tubules; acute cellular swelling; hyaline tubules; and acute tubular nephrosis. In contrast, Catha edulis treatment did not affect the spleen and increased the rate of spermatogenesis in male rabbits with the spermatozoa being quite evident, the Leydig cells were in good condition and were not affected by the doses given.

Cell surface events during resealing visualized by scanning-electron microscopy.

The function of exocytosis during plasma membrane resealing might be to facilitate the flow of surface lipid over the disruption site and/or to add defect-spanning "patches" of internal membrane across it. Scanning-electron-microscopic visualization of large plasma membrane disruptions in sea urchin eggs is here used to distinguish between these two possibilities. Disruptions were induced by shear stress in the presence and absence of resealing-permissive levels of external Ca2+, and the eggs were fixed at various intervals thereafter for microscopic processing. In eggs fixed immediately (<1 s) after shearing in the absence of Ca2+, a condition which prevents resealing, disruption sites were filled with a uniform population of spherical vesicles (approximately 1 microm in diameter). In eggs fixed immediately after shearing at a resealing-permissive level of Ca2+, disruption sites were filled with a highly heterogeneous population of enlarged vesicles, some being more than 10 microm in diameter and many having irregular profiles and/or appearing to be joined to one another. In eggs fixed 2 s or 5 s post-shearing, the continuity of these large vesicles with one another and the surface membrane began to obscure individual vesicle identities. Single "apertures" of discontinuity over disruption sites, the predicted morphology of a flow-based resealing mechanism, were not observed at any time point (1-5 s) during the interval required for completion of resealing. These observations provide strong confirmation that "patching" of large disruptions mediates their resealing.

Blockade of delta opioid receptors in the ventrolateral periaqueductal gray region inhibits the fall in arterial pressure evoked by hemorrhage.

Severe hemorrhage lowers arterial pressure by suppressing sympathetic activity. The central mechanism that initially triggers the fall in arterial pressure evoked by hemorrhage is not well understood, although opioid neurons are thought to play a role. This study tested the hypothesis that hemorrhagic hypotension is mediated by delta opioid receptors in the ventrolateral periaqueductal gray (vlPAG), a region importantly involved in opioid analgesia. Depressor sites were first identified by microinjecting DL-homocysteic acid (20 nmol/0.1 microl) or beta-endorphin (0.5 nmol/0.1 microl) into the vlPAG of halothane-anesthetized rats. Consistent with earlier reports, DL-homocysteic acid injection into the caudal vlPAG lowered arterial pressure and heart rate; beta-endorphin evoked a comparable depressor response, but did not affect heart rate. Naloxone or selective opioid receptor antagonists were subsequently injected into the vlPAG 5 min before hemorrhage (1.9 or 2.5 ml/100 g of body weight over 20 min) was initiated using the same stereotaxic coordinates. Naloxone injection into the caudal vlPAG completely prevented the fall in arterial pressure evoked by hemorrhage. The response was dose-dependent and evident with both fixed volume and fixed pressure hemorrhage. The delta opioid receptor antagonist naltrindole inhibited hemorrhagic hypotension significantly in both conscious and anesthetized rats but mu and kappa receptor antagonists were ineffective. beta-Endorphin(1--27), an endogenous opioid receptor antagonist, was also significantly inhibitory. Naltrindole was ineffective when injected into the dorsolateral periaqueductal gray and did not influence cardiovascular function in nonhemorrhaged animals. These data support the hypothesis that hemorrhagic hypotension is mediated by delta opioid receptors in the vlPAG.

Randomized, controlled, bilateral (split-face) comparison trial of the tolerability and patient preference of adapalene gel 0.1% and tretinoin microsphere gel 0.1% for the treatment of acne vulgaris.

Poor patient compliance is one of the main reasons for treatment failure in acne. Our objective was to evaluate the tolerability and patient preference of adapalene gel 0.1% compared with tretinoin microsphere gel 0.1% using a randomized, controlled, investigator-masked, bilateral (split-face), 4-week comparative study of the 2 products when applied once daily in 40 patients. We found that adapalene produced less stinging/burning than tretinoin at weeks 1 and 4 and, overall, more patients felt more skin irritation on the side of the face treated with tretinoin than on the side treated with adapalene (P<.05). At week 4, a significantly greater number of patients preferred adapalene gel 0.1% to tretinoin microsphere gel 0.1% (72.5% vs 27.5%, respectively, P<.01).

Patellofemoral pain syndrome in the female athlete.

Although PFS will continue to be a therapeutic challenge, the prognosis for most female athletes is good, especially if they are motivated and compliant with their treatment program. Particularly in women, care should be taken to avoid placing too much emphasis on biomechanical variants that may not be clinically significant or correctable because such findings can reinforce a feeling that "nothing can be done." In many cases, muscle dysfunction and repetitive loading of the patellofemoral joint rather than fixed biomechanical factors contribute to the development of PFS. Nonetheless, the importance of a detailed biomechanical assessment on physical examination must not be neglected, particularly in athletes who are not improving with conservative treatment and who may become surgical candidates. A practical initial treatment program for most athletes with nontraumatic PFS begins with relative rest, quadriceps strengthening, and stretching of tight myotendinous units. The introduction of NSAIDs, orthoses, taping, knee sleeves, and more specific rehabilitative exercises should be an individualized decision based on physical findings, past treatment results, and athletic expectations. Surgical referral should be considered in cases of PFS or patellar instability refractory to prolonged maximal nonoperative treatment.

Anterior cruciate ligament injuries in the female athlete.

The normal anterior cruciate ligament (ACL) is critical to knee joint stability, especially for athletes in cutting sports. Rupture of the ACL can be a devastating, if not career-ending, injury for a young athlete because of the resultant instability and increased risk of meniscal and chondral damage. Considerably more girls and women than ever before now participate in athletics. Some epidemiologic data show that female athletes may sustain a higher incidence of ACL injuries than male athletes. Risk factors that may be responsible for these increased injury rates are reviewed. History and physical examination are most important in establishing the diagnosis of ACL injury, although ancillary diagnostic imaging is helpful if the extent of injury is in question. Treatment options, including various surgical reconstructions and rehabilitation, are discussed, with attention to the specific concerns of the female athlete. With appropriate diagnosis and treatment, the ACL-injured athlete may now anticipate full return to function and athletic competition.

Immunochemical properties of abnormal hemoglobins C-Harlem (beta 6 Glu replaced by Val, beta 73 Asp replaced by Asn), S (beta 6 Glu replaced by Val), Korle Bu (beta 73 Asp replaced by Asn), Vancouver (beta 73 Asp replaced by Tyr), and Mobile (beta 73 Asp replaced by Val).

Antibodies were made to three mutant hemoglobins, each containing different single amino acid substitutions at beta 73:Hb Korle Bu (Asp replaced by Asn), Hb Mobile (Asp leads to Val), Hb Vancouver (Asp replaced by Tyr); and to one mutant hemoglobin, Hb C-Harlem, containing two substitutions in the beta chain (beta 6 Glu replaced by Val, as in Hb S, and beta 73 Asp replaced by Asn, as in Hb Korle Bu). The antiserum to Hb C-Harlem contained two antibody populations, each specific for one mutant amino acid residue. The antiserum to Hb Vancouver was completely specific for this mutant and did not cross-react with Hb Mobile and Hb Korle Bu; however, antiserum to Hb Korle Bu partially cross-reacted with Hb Mobile and to a smaller degree with Hb Vancouver. Antiserum to Hb Mobile exhibited even less cross-reactivity with Hb Korle Bu and C-Harlem and none with Hb Vancouver. These and previous studies indicate the involvement of at least three independent areas in the beta chain as antigenic determinant sites. It appears that the three mutants at beta 73 elicit the formation of antibodies which have a gradation in their specificity due to the nature of the amino acid sidechain.

Radioimmunochemical characterization of hemoglobins Lepore and Kenya: unique antigenic determinants located on hybrid hemoglobins.

Antisera were produced in rabbits to the three known types of Lepore hemoglobins, which contain hybrid delta-beta non-alpha-chains, and to hemoglobin Kenya, which has a hybrid gamma-beta non-alpha-chain. By using a sensitive radioimmunoassay technique, the absorbed antisera were shown to contain an antibody population that was specific for the hybrid hemoglobin and did not cross-react with normal hemoglobins. However, with the absorbed Lepore-specific antisera, the three known types of Lepore hemoglobins were antigenically indistinguishable from each other, suggesting that antibodies are not produced to the primary structural differences which define the three non-alpha-chains of the Lepore hemoglobins. These studies demonstrate that the non-alpha-subunits of hemoglobins Lepore and Kenya possess unique antigenic determinant sites, evidently resulting from an altered polypeptide conformation.

Specific radioimmunochemical identification and quantitation of hemoglobins A2 and F.

Hyperimmune antisera to chromatographically purified hemoglobins F and A2 were produced in rabbits and made specific for the immunogen by adsorption with normal human hemoglobin A conjugated to cyanogen bromide-activated agarose. A radioimmunoassay was established that permitted identification and quantitation of each of these two minor hemoglobins in hemolysates containing other hemoglobin components. The quantities of hemoglobins A2 and/or F present in hemolysates of individuals with beta-thalassemia, sickle cell anemia, Hb-C disease, and other hematological disorders were determined immunochemically, and the results were commpared to values obtained by microcolumn chromatography for the measurement of Hb-A2 or with the alkali denaturation technique in quantitating Hb-F. The immunoassay procedure has a greater sensitivity than other commonly employed techniques and can detect as little as 0.05 mug of these hemoglobins.