Densitometric Measurements Research Articles

Incidental Pancreatic Lipomas Diagnosed by Computed Tomography

Fatty tumours of the pancreas are rarely reported. With the advent of the imaging techniques, diagnosis of such tumours based on radiologic imaging is increasing.Between June 2006 and June 2012, four patients with pancreatic lipomas that were diagnosed by computed tomography were reviewed retrospectively with regard to their imaging findings. There were 3 male and one female patient with a mean age of 60.8 years (from 53 to 67 years).A single well-bordered nodular fatty lesion with well-delineated thin homogeneous capsule was seen in all patients. The mean densitometric measurement of the lesions was -76 Hounsfield units (HU) (from -83 HU to -63 HU). The size of the lesions was from 7 mm to 12 mm with a mean of 8.75mm. They were located in the tail, body and neck of the pancreas in two, one and one patient, respectively. There was no associated pancreatobiliary pathology. Histopathologic evaluation was not planned because of their incidental diagnosis in these asymptomatic patients.Pancreatic lipomas are silent lesions, incidentally found during imaging procedures. They have specific computed tomography findings and do not require any additional diagnostic imaging.Pankreasın yağlı tümörleri nadiren bildirilmektedir. Görüntüleme yöntemlerinin yaygınlaşması ile bu tür tümörlerin radyolojik görüntüleme temelli tanısı giderek artmaktadır.Haziran 2006–2012 dönemi arasında bilgisayarlı tomografi ile tanı konulan pankreas lipomlu dört hasta, görüntüleme bulguları açısından retrospektif olarak değerlendirildi. Ortalama yaşı 60.8 yıl (değer aralığı 53–67 yıl) olan 3 erkek ve bir kadın hasta vardı.Hastaların tamamında, ince homojen kapsüllü ve düzenli sınırlı nodüler yağlı tek bir lezyon görüldü. Ortalama densitometrik ölçüm değeri −76 Hounsfield ünitesi (HU) (değer aralığı −83 ile −63 arası) idi. Lezyonların büyüklüğü 7 ile 12 mm arası (ortalama 8,75 mm) değişiyordu. İki hastada kuyrukta olmak üzere, diğerleri gövde ve boyun bölgesi yerleşimli idi. Eşlik eden pankreatobiliyer patoloji yoktu. Asemptomatik hastalarda rastlantısal tanı nedeniyle, histopatolojik inceleme planlanmadı.Pankreas lipomları görüntüleme yöntemleri esnasında rastlantısal olarak görülen sessiz lezyonlardır. Spesifik tanısal bulguları olması nedeniyle ilave girişimlere ihtiyaç yoktur.

Sensitive and Robust Methods for Simultaneous Determination of Beclomethasone Dipropionate and Formoterol Fumarate Dihydrate in Rotacaps

Fixed dose combination containing beclomethasone dipropionate (BDP) and formoterol fumarate dihydrate (FFD) is used in the treatment of asthma in form of dry powder inhaler. Two methods are described for the simultaneous determination of BDP and FFD in commercial rotacap formulation. The first method was based on HPTLC separation of the two drugs followed by densitometric measurements of their spots at 220 nm. The separation was carried out on Merck HPTLC aluminum sheets precoated with silica gel 60F254 using hexane:ethyl acetate:methanol:formic acid (2.0:2.5:2.0:0.2, v/v/v/v) as mobile phase. The linearity was found to be in the range of 2.4-8.4 µg/spot and 80-280 ng/spot for BDP and FFD, respectively. The second method was based on HPLC separation of the two drugs on the reversed phase Enable HPLC Analytical C18 G 120Å (250 × 4.6 mm, 5 µm) column at ambient temperature using a mobile phase consisting of methanol:acetonitrile:phosphate buffer adjusted to pH 3.6 using orthophosphoric acid (65:25:10, v/v/v). Quantitation was achieved with UV detection at 220 nm based on peak area with linear calibration curves at concentration ranges of 10-200 and 0.3-6.0 µg/mL for BDP and FFD, respectively. Both methods were validated in terms of precision, robustness, recovery and limits of detection and quantitation. The robustness of both methods was assessed using experimental design and results were analyzed by statistical and graphical approaches. Rotacaps formulation containing BDP (200/400 μg) and FFD (6 μg) were successfully quantified using the proposed methods. The proposed methods can be used as sensitive, precise, accurate and robust methods for quantification of BDP and FFD in Rotacaps.

Development and Validation of a High-Performance Thin-Layer Chromatographic Method for the Assay of Ternary Mixtures Containing Cetirizine Dihydrochloride in Pharmaceutical Dosage Forms

A highly validated and selective high-performance thin-layer chromatography (HPTLC) method was developed for the determination of cetirizine dihydrochloride (CET) with pseudoephedrine (PSE) and/or phenylpropanolamine (PPA) and paracetamol (PAR) in their pharmaceutical formulations. The proposed method was based on HPTLC separation of the drugs followed by densitometric measurements of their spots at 257 nm. Separation was carried out on Merck HPTLC aluminum sheets of silica gel 60 F254 using methanol-distilled water (9.95:0.05, v/v) as mobile phase. The linear regression analysis data were used for the regression line in the range of 1–4, 3–10, 4–8, and 5–100 µg band−1 for CET, PSE, PPA, and PAR, respectively. The proposed method was validated and successfully applied for the analysis of pharmaceutical formulations and laboratory-prepared mixtures containing the two multicomponent combinations. The method is validated and showed good performances in terms of linearity, sensitivity, precision, accuracy, and stability.

Incidental pancreatic lipomas diagnosed by computed tomography.

Fatty tumours of the pancreas are rarely reported. With the advent of the imaging techniques, diagnosis of such tumours based on radiologic imaging is increasing. Between June 2006 and June 2012, four patients with pancreatic lipomas that were diagnosed by computed tomography were reviewed retrospectively with regard to their imaging findings. There were 3 male and one female patient with a mean age of 60.8 years (from 53 to 67 years). A single well-bordered nodular fatty lesion with well-delineated thin homogeneous capsule was seen in all patients. The mean densitometric measurement of the lesions was -76 Hounsfield units (HU) (from -83 HU to -63 HU). The size of the lesions was from 7 mm to 12 mm with a mean of 8.75mm. They were located in the tail, body and neck of the pancreas in two, one and one patient, respectively. There was no associated pancreatobiliary pathology. Histopathologic evaluation was not planned because of their incidental diagnosis in these asymptomatic patients. Pancreatic lipomas are silent lesions, incidentally found during imaging procedures. They have specific computed tomography findings and do not require any additional diagnostic imaging.

Correlation between computerized tomography density measurements of urinary bladder and urinalysis results

Our aim was to investigate whether there is a correlation between computerized tomography (CT) density measurements of the urinary bladder and urinalysis results. Patients were subdivided into three groups with respect to urinalysis results: Group 1, no leukocytes or erythrocytes detected in urine (n=25); Group 2, erythrocytes detected in urine (n=50); and Group 3, leukocytes and erythrocytes detected in urine (n=98). In CT sections, densitometric measurements had been performed from three zones on each section and groups were compared in terms of densitometry results. Our results indicate that density measurements of CT views form the urinary bladder may provide valuable data on hematuria and leukocyturia.

Development and Validation of Densitometry TLC Stability Indicating Method for Quantitative Determination of Azelastine Hydrochloride and Emedastine Difumarate in Their Drug Products

Aims: Stability indicating densitometry-TLC assay was established and validated for determination of azelastine hydrochloride (AZT) and emedastine difumarate (ETD) in the presence of their acid and oxidative degradants. Methodology: Forced degradation was performed using 30% H2O2 and 5 M HCl. The method was based on thin-layer chromatographic separation of the two drugs from their degradants, using methanol- 10% ammonia (9.5:0.5, v/v) as developing system, followed by densitometric measurements of the intact drug spots at 292 and 283 nm, for azelastine hydrochloride and emedastine difumarate respectively. Results: The linear range was 0.5 - 10.0 μg/spot, with mean recoveries of 100.09 ± 0.53% and 100.36 ± 0.40% for azelastine hydrochloride and emedastine difumarate respectively. Conclusion: The proposed method was successfully applied for the routine quality control analysis of both drugs in laboratory prepared mixtures and commercially available preparations. The degradation products were identified by IR and MS and the pathways were illustrated. The method was validated according to ICH.

Morphometric, densitometric and mechanical properties of mandibular deciduous teeth in 5-month-old Polish Merino sheep

BackgroundCaries, enamel hypoplasia, molar incisor hipomineralization, amylogenesis imperfecta, dentine dysplasia, hypophosphatasia and other dental disorders lead to tooth mineralization disturbances and structural abnormalities, decreasing masticatory organ functions. Dental disorders in sheep can lead to premature slaughter before they have attained final stage of their reproductive life and induce economic loss due to high flock replacement costs. Growth rate, health status and meat quality of sheep depends on tooth properties and quality determining in large extent efficiency of the masticatory apparatus and initial food break up. Considering lack of basic anatomical and physiological data on teeth properties in sheep, the aim of the study was to evaluate morphometric, densitometric and mechanical traits of deciduous mandibular incisor, canine and the second premolar obtained at the slaughter age of 5 months of life.ResultsThe obtained results have shown the highest values of weight, total tooth volume, enamel volume and dentine volume in second premolar. Morphometric and mechanical parameters of incisors reached the highest values in first incisor and decreased gradually in second and third incisor, and in canine. Densitometric measurements have not revealed significant differences of the volumetric tooth mineral density in hard dental tissues between the investigated teeth.ConclusionsIn conclusion, proposed methodological approach is noninvasive since the deciduous teeth undergo physiological replacement with permanent teeth. Deciduous teeth can be easy collected for analyses from large animal population and may reflect mineral status and metabolism resulting from postnatal growth and development of the whole flock. In individual cases, evaluation of properties of deciduous teeth may serve for breeding selection and further reproduction of sheep possessing favorable traits of teeth and better masticatory system functions.

Development and Validation of HPTLC Method for Simultaneous Estimation of Metolazone and Spironolactone in Bulk Drug and Pharmaceutical Dosage Form

A simple, precise and accurate HPTLC method has been developed for the simultaneous analysis of Metolazone and Spironolactone in bulk drugs and tablet formulation. Chromatographic separation was carried out on Merck HPTLC aluminium plates of Silica gel 60 F254, using n-propanol : triethylamine (7:3 v/v) as the mobile phase. HPTLC separation of the two drugs followed by densitometric measurement was performed in the absorbance mode at 240 nm. The drugs were resolved with R f values of 0.60 and 0.69 for Metolazone and Spironolactone respectively. The linear regression analysis data for the calibration plots showed good linear relationship with r value 0.99886 and 0.99862 for Metolazone and Spironolactone, respectively in the concentration range of 300 -700 ng/spot for Metolazone and 300-700 ng/spot for Spironolactone. The method was validated following the ICH guidelines in terms of accuracy, precision, specificity and robustness. The limit of detection and quantitation were 200 and 600 ng/spot respectively for Metolazone and 200 and 600 ng/spot for Spironolactone. The proposed developed and validated HPTLC method can be utilised for identification and quantitative analysis of Metolazone and Spironolactone in bulk drugs and pharmaceutical dosage form.

Validated Stability-indicating HPLC and Thin Layer Densitometric Methods for the Determination of Pazufloxacin: Application to Pharmaceutical Formulation and Degradation Kinetics

Two stability indicating methods were developed for the determination of pazufloxacin in presence of its acidic and alkaline degradation products, in pure form and in IV injection. The first method was based on RP-HPLC on X-terra C18 column (25 cm×4.6 mm×5 μm) using methanol and 0.5% phosphoric acid (15:85 (v/v)) with the addition of 1% Triethylamine (TEA) as a mobile phase over a concentration range 2-40 μg ml-1 and a mean percentage recovery of 100.467 ± 0.595. Quantification was achieved with UV detection at 249 nm. The second method was based on TLC separation of pazufloxacin from its degradation products followed by Densitometric measurement of the intact drug spot at 249 nm. The separation was carried out on silica gel 60 F254 aluminum sheets using chloroform, methanol and ammonia (10: 8: 2 v/v/v), as the mobile phase over a concentration range 0.1-2 μg per spot and mean percentage recovery of 99.694 ± 0.539. The two methods were simple, precise, and sensitive that could be successfully applied for the determination of pure and intravenous (IV) injection. The proposed HPLC method was used for the determination of acidic and alkaline degradation kinetics of pazufloxacin. The apparent first-order rate constants, half-life times, and activation energies of the degradation processes were calculated.

Validated TLC-densitometry method for determination of cetirizine dihydrochloride in tablet dosage form

A rapid, reproducible and accurate TLC method was developed for the determination of Cetirizine Dihydrochloride in tablet. The analytes were dissolved with ethanol 70% and chromatographed on silica Gel GF 254 TLC plate using chloroform : methanol : ethyl acetate in the ratio of 2 : 7 : 3 (v/v) as mobile phase. Quantitative analysis was done through densitometric measurement at wavelength 234 nm. Method was found linear over the concentration range of 400 – 1600 ng/spot with the correlation coefficient of 0.996. Specificity showed calculation of purity and identity more than 0.99. The limit of detection (LOD) and the limit of quantification (LOQ) of the method were 75.54 and 226.64 ng/spot. The relative standard deviation of this method was 0.86% whereas the means of the recovery data was 100.54 ± 0.11%. The proposed method has been applied to the determination of Cetirizine Dihydrochloride in commercial tablet formulations and the result were 96.97 ± 0.86 % for brand A and 100.57 ± 1.17 % for brand B. The developed method was successfully used for the assay of Cetirizine Dihydrochloride. This method is simple, sensitive and precise; it can be used for the routine quality control testing of marketed formulations.DOI: http://dx.doi.org/10.3329/icpj.v3i1.17294 International Current Pharmaceutical Journal, December 2013, 3(1): 208-210

Avaliação dos fatores de risco de quedas em mulheres na pós-menopausa inicial

It was to evaluate the frequency and the risk factors of falls in early postmenopausal women. A cross-sectional study was conducted on 358 women (age: 45-65 years and amenorrhea >12 months) with time since menopause <10 years. Exclusion criteria were: neurological or musculoskeletal disorders, vestibulopathies, uncorrected visual deficit, uncontrolled hypertension and postural hypotension, or drug use (sedative and hypnotic agents). A fall was identified as an unexpected unintentional change in position which causes an individual to remain in a lower level in relation to the initial position. The history of self-reported falls during the previous 24 months, and clinical and anthropometric data (body mass index (BMI) and waist circumference (WC)) and bone densitometric measures were analyzed. For statistical analysis, c² trend test and the logistic regression method (odds ratio (OR)) were used for the comparison between groups of women with and without falls. Of the 358 women, 48.0% (172/358) had a history of falls and 17.4% (30/172) had fractures. The fall occurred indoors (at home) in 58.7% (101/172). The mean age was 53.7 ± 6.5 years, time since menopause 5.8 ± 3.5 years, BMI 28.3 ± 4.6 kg/m² and WC 89.0 ± 11.4 cm. There were differences as the occurrence of smoking and diabetes, with greater frequency among fallers vs. non-fallers, 25.6 versus 16.1% and 12.8 versus 5.9%, respectively (p<0.05). By evaluating the risk of falls in the presence of influential variables, it was observed that risk increased with current smoking status (OR 1.93; 95%CI 1.01-3.71), whereas other clinical and anthropometric variables did not influence this risk. In early postmenopausal women there was higher frequency of falls. Current smoking was clinical indicators of risk for falls. With the recognition of factors for falling, preventive measures become important, as the orientation of abolishing smoking.

Are computed tomography and densitometric measurements useful in otosclerosis with mixed hearing loss? A retrospective clinical study

The objective of the study was to investigate the relationship between extent of otosclerotic foci and audiological findings in otosclerotic patients with mixed hearing loss using high-resolution computed tomography (HRCT) and also to measure the density of bony labyrinth in otosclerotic patients and compared with control group. This was a retrospective study. Twenty-five patients with clinical otosclerosis and mixed hearing loss were included in the study. The average threshold of air-bone conductions (AC, BC) within the 0.5-4 kHz frequency range, and average air bone gap (ABG) were calculated. Eleven patients with normal HRCT who received cochlear implant were included in the study as the control group. The lesions in HRCT were staged according to their extension. Eight different points of the otic capsule in each patient were measured using HRCT. Fifty ears total, from 25 patients, had bilateral otosclerosis. The mean AC of all the ears was 63 dB, mean BC was 35.2 dB, and mean ABG was 27.8 dB. HRCT staging indicated 22 ears had Grade 1, 21 ears had Grade 2, and 7 ears had Grade 3 lesions. There was a statistically significant difference between the mean AC, BC of ears with Grade 1 and Grade 2 when compared with the mean AC, BC of ears with Grade 3. When comparing the densitometric measurements of fissula ante fenestram localizations, a statistically significant difference was observed. HRCT examination and densitometric measurements in otosclerotic patients with mixed hearing loss presented significant results. We were unable to show a significant relationship between early stage and hearing thresholds, but there was a significant relationship in advanced stage. Densitometric measurements may provide significant results for otosclerosis, particularly for the FAF region when comparing with control group.

Densitometric measurement for estimation of ciclesonide in bulk and its dosage form (rotacap) by high-performance thin-layer chromatography

A sensitive method based on high-performance thin-layer chromatography (HPTLC) by using principle of densitometry with UV detection at 7nmax 242 nm for quantitative estimation of major pharmaceutically active compound, ciclesonide, 2-[(1S,2S,4R,8S,9S,11S,12S,13R)-6-cyclohexyl-11-hydroxy-9,13-dimethyl-16-oxo-5,7-dioxapentacyclo[10.8.0.02,9.04,8.013,18]icosa-14,17-dien-8-yl]-2-oxoethyl-2-methylpropanoate, which persists as a newer antiasthmatic drug of glucocorticoid class, is described here. Chromatographic separation was performed by semiautomatic CAMAG HPTLC instrument. The method was validated according to the International Conference on Harmonization (ICH) guidelines, illustrating to be accurate (98.92–100.26%) and precise (CV = 0.43–0.67 for intra-day and CV = 0.58–1.45 for inter-day) within the corresponding linear range. Limit of detection (LOD) and limit of quantification (LOQ) of sample were found to be 100 ng/spot and 303 ng/spot, respectively.

Application of LC and HPTLC-densitometry for the simultaneous determination of two multicomponent mixtures containing pyridoxine hydrochloride and cyanocobalamine

Summary Two methods were presented for the simultaneous determination of two multicomponent mixtures containing pyridoxine hydrochloride (B6) and cyanocobalamine (B12) with benfotiamine (BN) [mix. 1], or thiamine nitrate (B1) and diclofenac sodium (DC) [mix. 2]. The first high-performance liquid chromatographic (HPLC) method depends on the use of a cyanopropyl column at a flow rate of 1.5 mL min−1 with a mobile phase consisting of acetonitrile-25 mM ammonium acetate, pH 3.7 (10:90, v/v), for mix. 1 or acetonitrile-25 mM ammonium acetate, pH 5.0 by gradient elution, changing the proportion of the system linearly with a time schedule program, for mix. 2. Quantitation was achieved by UV detection at 220 nm. The second method was based on HPTLC separation followed by densitometric measurement of the spots at 254 nm. The separation was achieved on HPTLC silica gel F254 plates using chloroform-ethanol-water-acetic acid (5:8:2:0.5, v/v/v/v) for mix. 1 and chloroform-ethanol-water-acetic acid (1.5:8:2:0.5, v/v/v/...

Restoration of Glutamatergic Transmission by Dopamine D4 Receptors in Stressed Animals

The prefrontal cortex (PFC), a key brain region for cognitive and emotional processes, is highly regulated by dopaminergic inputs. The dopamine D4 receptor, which is enriched in PFC, has been implicated in mental disorders, such as attention deficit-hyperactivity disorder and schizophrenia. Recently we have found homeostatic regulation of AMPA receptor-mediated synaptic transmission in PFC pyramidal neurons by the D4 receptor, providing a potential mechanism for D4 in stabilizing cortical excitability. Because stress is tightly linked to adaptive and maladaptive changes associated with mental health and disorders, we examined the synaptic actions of D4 in stressed rats. We found that neural excitability was elevated by acute stress and dampened by repeated stress. D4 activation produced a potent reduction of excitatory transmission in acutely stressed animals and a marked increase of excitatory transmission in repeatedly stressed animals. These effects of D4 targeted GluA2-lacking AMPA receptors and relied on the bi-directional regulation of calcium/calmodulin kinase II activity. The restoration of PFC glutamatergic transmission in stress conditions may enable D4 receptors to serve as a synaptic stabilizer in normal and pathological conditions.

A Comment on ‘Changes in Bone Mineral Density in Women Following 1-year Gastric Bypass Surgery’ Published by Casagrande DS et al.

Sirs,In a recent issue of Obesity Surgery, a study on longitudinalchanges in bone mineral density (BMD) after gastric bypasssurgery [1] was published. The authors presented severallaboratory data and BMD measurements at the spine andproximal femur at baseline and follow-up. Generally,both laboratory variables and BMD results have changedsignificantly. However, we have comments concerningmethodology of BMD measurements and the way of theirpresentation.Firstly, in a description of densitometry, the authors didnot provide a precision expressed as coefficient of variation(CV%). This information is especially important in a longi-tudinal observation. In each densitometry unit, serial mea-surements should be performed and CV% should beestablished. Moreover, in a prospective study, it is necessaryto calculate the value of the least significant change (LSC)using a common formula: RMS_CV×2×1.41. The use ofLSC allows to establish whether the BMD change in anindividual subject exceed the value of LSC.The authors presented changes in BMD only as meanexpressed in percent. Such way of presentation does notexpress real bone changes in a satisfactory manner. Onemay expect that due to precision error BMD change not ineach patient will exceed the value of LSC. In our recentstudy, we performed measurements in 29 women after lapa-roscopic sleeve gastrectomy, and after 6 months, BMD havedecreased for femoral neck, total hip and spine by 1.24, 6.99and 5.18 %, respectively [2]. We also performed an analysisof changes in individual patients using LSC, and such wayallowstoestablishthatchangeinBMDwasnotpresentinallpatients. For spine, BMD decreased only in 38 % of allwomen, andin three of them BMD even increased. In regardto femoral neck BMD, real decrease was noted in 72 %, andfor total hip BMD, a decrease exceeding the value of LSCwas observed in 82 % of all subjects studied. For hip densi-tometric measurements, an increase was not noted but insome women a decrease was not present.Our analysis confirms that we should not expect thepresence of significant bone changes in all subjects aftersurgical method of treatment of obesity. We recommend forauthorsofthecommentedstudytopresentsuchdatathatwillhelpinbetterunderstandingofbonechangesinsubjectsaftersurgical obesity management.References

SIMULTANEOUS DETERMINATION OF PRAMOCAINE HCL AND HYDROCORTISONE ACETATE IN PHARMACEUTICAL DOSAGE FORM

Two sensitive and selective methods were developed and validated for simultaneous determination of pramocaine HCl and hydrocortisone acetate in pharmaceutical dosage form. The first method is a spectrodensitometric method where pramocaine HCl and hydrocortisone acetate were separated using toluene:methanol:chloroform: 10% NH3 [(5:3:6:0.1, by volume) as the developing system followed by densitometric measurement at 290 nm] and 250 nm for pramocaine HCl and Hydrocortisone acetate, respectively. The second method is a high performance liquid chromatographic method for separation and determination of both drugs using reversed phase C18 column and mobile phase consisting of distilled water:acetonitrile:triethylamine (530:470:0.1, by volume); pH was adjusted to 3 by o-phosphoric acid. The proposed methods were successfully applied for the analysis of pramocaine HCl and hydrocortisone acetate in laboratory prepared mixtures and in pharmaceutical dosage form and the results obtained were assessed by applying the standard addition technique. Statistical comparison between the results obtained by applying the proposed methods and official method for the cited drugs was done and no significant difference was found at p = 0.05.

A new high-performance thin-layer chromatographic method for determination of diazepam in spiked blood samples

A high-performance thin-layer chromatographic method combined with densitometric measurement and UV scanning was used to optimize a new mobile phase consisting of hexane and ethyl acetate (7:3 v/v) for the estimation of diazepam in spiked human blood. Efficacy and ease of extraction with three solvents, acetonitrile, diethyl ether, and chloroform, each at three different pH conditions were studied. Validation parameters for diazepam were found to be linear in the range of 0.5–20 μg/spot with r = 0.998, limit of detection (LOD), 0.2 μg, limit of quantification (LOQ), 0.5 μg. Usefulness of the new mobile phase for the separation of six common benzodiazepines, namely, nitrazepam, clonazepam, lorazepam, chlordiazepoxide, alprazolam, and clozapine from diazepam, was proved through their retention factor and UV pattern.

Stability-Indicating HPLC and RP-TLC Determination of Cefpirome Sulfate with Kinetic Study

Two sensitive and selective stability-indicating methods were developed for the determination of the antibiotic cefpirome sulfate in bulk powder, pharmaceutical formulation and in presence of its acid, alkaline, photo- and oxidative degradation products. Method A was based on HPLC separation of cefpirome sulfate in the presence of its degradation products on a reversed phase column C18, 250 × 4.6 mm, 5-μm particle size and mobile phase consisting of 0.1 M disodium hydrogen phosphate dihydrate pH 3.9 adjusted with phosphoric acid–acetonitrile (85:15, v/v). Quantitation was achieved with UV detection at 270 nm. The linear calibration curve was in the range 5.0–50.0 μg mL−1. Method B was based on reversed phase TLC separation of the cited drug in the presence of its degradation products followed by densitometric measurement of the intact drug at 270 nm. The separation was carried out using disodium hydrogen phosphate dihydrate 2.0 g %w/v, at pH 3.5 adjusted with phosphoric acid–acetone (15:10, v/v) as a developing system. The calibration curve was in the range of 1.0–10.0 μg/spot. The HPLC method was used to study the kinetic of cefpirome sulfate acid degradation. The results obtained were statistically analyzed and compared with those obtained by applying the official Japanese method.

Previous exposure to simulated microgravity does not exacerbate bone loss during subsequent exposure in the proximal tibia of adult rats

Extended periods of inactivity cause severe bone loss and concomitant deterioration of the musculoskeletal system. Considerable research has been aimed at better understanding the mechanisms and consequences of bone loss due to unloading and the associated effects on strength and fracture risk. One factor that has not been studied extensively but is of great interest, particularly for human spaceflight, is how multiple or repeated exposures to unloading and reloading affect the skeleton. Space agencies worldwide anticipate increased usage of repeat-flier crewmembers, and major thrust of research has focused on better understanding of microgravity effects on loss of bone density at weightbearing skeletal sites; however there is limited data available on repeat microgravity exposure. The adult hindlimb unloaded (HU) rat model was used to determine how an initial unloading cycle will affect a subsequent exposure to disuse and recovery thereafter. Animals underwent 28days of HU starting at 6months of age followed by 56days of recovery, and then another 28days of HU with 56days of recovery. In vivo longitudinal pQCT was used to quantify bone morphological changes, and ex vivo μCT was used to quantify trabecular microarchitecture and cortical shell geometry at the proximal tibia metaphysis (PTM). The mechanical properties of trabecular bone were examined by the reduced platen compression mechanical test. The hypothesis that the initial HU exposure will mitigate decrements in bone mass and density for the second HU exposure was supported as pre- to post-HU declines in total BMC, total vBMD, and cortical area by in vivo pQCT at the proximal tibia metaphysis were milder for the second HU (and not significant) compared to an age-matched single HU (3% vs. 6%, 2% vs. 6%, and 2% vs. 6%, respectively). In contrast, the hypothesis was not supported at the microarchitectural level as losses in BV/TV and Tb.Th. were similar during 2nd HU exposure and age-matched single HU. Recovery with respect to post-HU values and compared to aging controls for total BMC, vBMD and cortical area were slower in older animals exposed to single or double HU cycles compared to recovery of younger animals exposed to a single HU bout. Despite milder recovery at the older age, there was no difference between unloaded animals and controls at the end of second recovery period. Therefore, the data did not support the hypothesis that two cycles of HU exposure with recovery would have a net negative effect. Mechanical properties of trabecular bone were affected more severely than densitometric measures (35% loss in trabecular bone ultimate stress vs. 9% loss in trabecular vBMD), which can be attributed most prominently to reductions in trabecular bone density and tissue mineral density. Together, our data demonstrate that initial exposure to mechanical unloading does not exacerbate bone loss during a subsequent unloading period and two cycles of unloading followed by recovery do not have a cumulative net negative effect on total bone mineral content and density as measured by pQCT at the proximal tibia metaphysis.