Spatial Atlas for Mapping Vascular Microcalcification Using 18F-NaF PET/CT: Application in Hyperphosphatemic Familial Tumoral Calcinosis

BACKGROUND

Vascular calcification causes significant morbidity and occurs frequently in diseases of calcium/phosphate imbalance. Radiolabeled sodium fluoride positron emission tomography/computed tomography has emerged as a sensitive and specific method for detecting and quantifying active microcalcifications. We developed a novel technique to quantify and map total vasculature microcalcification to a common space, allowing simultaneous assessment of global disease burden and precise tracking of site-specific microcalcifications across time and individuals.

METHODS

To develop this technique, 4 patients with hyperphosphatemic familial tumoral calcinosis, a monogenic disorder of FGF23 (fibroblast growth factor-23) deficiency with a high prevalence of vascular calcification, underwent radiolabeled sodium fluoride positron emission tomography/computed tomography imaging. One patient received serial imaging 1 year after treatment with an IL-1 (interleukin-1) antagonist. A radiolabeled sodium fluoride-based microcalcification score, as well as calcification volume, was computed at all perpendicular slices, which were then mapped onto a standardized vascular atlas. Segment-wise mCSmean and mCSmax were computed to compare microcalcification score levels at predefined vascular segments within subjects.

RESULTS

Patients with hyperphosphatemic familial tumoral calcinosis had notable peaks in microcalcification score near the aortic bifurcation and distal femoral arteries, compared with a control subject who had uniform distribution of vascular radiolabeled sodium fluoride uptake. This technique also identified microcalcification in a 17-year-old patient, who had no computed tomography-defined calcification. This technique could not only detect a decrease in microcalcification score throughout the patient treated with an IL-1 antagonist but it also identified anatomic areas that had increased responsiveness while there was no change in computed tomography-defined macrocalcification after treatment.

CONCLUSIONS

This technique affords the ability to visualize spatial patterns of the active microcalcification process in the peripheral vasculature. Further, this technique affords the ability to track microcalcifications at precise locations not only across time but also across subjects. This technique is readily adaptable to other diseases of vascular calcification and may represent a significant advance in the field of vascular biology.

Rapamycin Inhibits Senescence and Improves Immunomodulatory Function of Mesenchymal Stem Cells Through IL-8 and TGF-β Signaling

Mesenchymal stromal cells (MSCs) grown in high-density monolayers (sheets) are promising vehicles for numerous bioengineering applications. When MSC sheets are maintained in prolonged cultures, they undergo rapid senescence, limiting their downstream efficacy. Although rapamycin is a potential agent that can inhibit senescence in cell cultures, no study has investigated rapamycin's effect on MSCs grown in high-density culture and its effect on downstream target gene expression. In this study, placental-derived MSCs (PMSCs) were seeded at high density to generate PMSC sheets in 24 hours and were then treated with rapamycin or vehicle for up to 7 days. Autophagy activity, cell senescence and apoptosis, cell size and granularity, and senescence-associated cytokines (IL-6 and IL-8) were analyzed. Differential response in gene expression were assessed via microarray analysis. Rapamycin significantly increased PMSC sheet autophagy activity, inhibited cellular senescence, decreased cell size and granularity at all timepoints. Rapamycin also significantly decreased the number of cells in late apoptosis at day 7 of sheet culture, as well as caspase 3/7 activity at all timepoints. Notably, while rapamycin decreased IL-6 secretion, increased IL-8 levels were observed at all timepoints. Microarray analysis further confirmed the upregulation of IL-8 transcription, as well as provided a list of 396 genes with 2-fold differential expression, where transforming growth factor-β (TGF-β) signaling were identified as important upregulated pathways. Rapamycin both decreased senescence and has an immunomodulatory action of PMSCs grown in sheet culture, which will likely improve the chemotaxis of pro-healing cells to sites of tissue repair in future bioengineering applications.

Emerging Role of 18F-NaF PET/Computed Tomographic Imaging in Osteoporosis: A Potential Upgrade to the Osteoporosis Toolbox

Osteoporosis is a metabolic bone disorder that leads to a decline in bone microarchitecture, predisposing individuals to catastrophic fractures. The current standard of care relies on detecting bone structural change; however, these methods largely miss the complex biologic forces that drive these structural changes and response to treatment. This review introduces sodium fluoride (18F-NaF) positron emission tomography/computed tomography (PET/CT) as a powerful tool to quantify bone metabolism. Here, we discuss the methods of 18F-NaF PET/CT, with a special focus on dynamic scans to quantify parameters relevant to bone health, and how these markers are relevant to osteoporosis.

The Influence of Analgesic Modalities on Postoperative Cancer Recurrence

The potential for cancer cells to grow and to metastasize depends on complex interactions between inflammatory signals and pathways, immune cells, and elements of the stromal tissue in which they invade. Related to the nature of many cancers, the probability of recurrence can potentially be quite high for some patients. Immunology, lifestyle modifications, timing of disease, genetics, age, gender, and race are only a handful of ways the likelihood of cancer recurrence can be influenced. The quantity, or density, of certain immunological cells or factors, plays a role in the propagation of cancer cells. Opioids are often used in cancer patients for acute postoperative and chronic pain management. While they can produce significant pain relief, the type of analgesic utilized is important, as it may influence cancer propagation. In this regard, certain opioids have been found to increase T regulatory cells while suppressing NK cell function. Morphine may promote tumor neovascularization and expansion. Fentanyl administration significantly diminishes NK-cells and CD8+ cytotoxic T-cells. In a recent meta-analysis, propofol-based anesthesia improved both cancer-free survival and overall survival. COX inhibitors have also shown promise in persevering cancer immune function, as in literature involving ketorolac and celecoxib. In summary, inhaled anesthesia and opioids may contribute to a pro-tumor metastasis environment also known as cancer propagation; whereas propofol and COX inhibitors may provide a better alternative to reduce cancer recurrence and propagation.

Understanding Reactive Oxygen Species in Bone Regeneration: A Glance at Potential Therapeutics and Bioengineering Applications

Although the complex mechanism by which skeletal tissue heals has been well described, the role of reactive oxygen species (ROS) in skeletal tissue regeneration is less understood. It has been widely recognized that a high level of ROS is cytotoxic and inhibits normal cellular processes. However, with more recent discoveries, it is evident that ROS also play an important, positive role in skeletal tissue repair, specifically fracture healing. Thus, dampening ROS levels can potentially inhibit normal healing. On the same note, pathologically high levels of ROS cause a sharp decline in osteogenesis and promote nonunion in fracture repair. This delicate balance complicates the efforts of therapeutic and engineering approaches that aim to modulate ROS for improved tissue healing. The physiologic role of ROS is dependent on a multitude of factors, and it is important for future efforts to consider these complexities. This review first discusses how ROS influences vital signaling pathways involved in the fracture healing response, including how they affect angiogenesis and osteogenic differentiation. The latter half glances at the current approaches to control ROS for improved skeletal tissue healing, including medicinal approaches, cellular engineering, and enhanced tissue scaffolds. This review aims to provide a nuanced view of the effects of ROS on bone fracture healing which will inspire novel techniques to optimize the redox environment for skeletal tissue regeneration.

Association between known risk factors and colorectal cancer risk in Indigenous people participating in the Ontario Familial Colon Cancer Registry

Introduction

Colorectal cancer is one of the most common cancers in Ontario and imposes a high burden on many Indigenous populations. There are two aims for this short communication: ■ Highlight colorectal risk factor findings from a population-based case-control study■ Highlight trends and challenges of colorectal cancer research in Indigenous populations in Ontario.

Methods

Prevalences of cigarette smoking, obesity, fruit and vegetable consumption, and family history of colorectal cancer were estimated using the Indigenous identifier in the Ontario Familial Colon Cancer Registry for 1999-2007 and then compared for cases and controls using age-adjusted odds ratios (ors) with 95% confidence intervals (cis).

Results

The registry search identified 66 Indigenous cases and 23 Indigenous controls. Cigarette smoking (or: 1.88; 95% ci: 0.63 to 5.60) and obesity (or: 2.16; 95% ci: 0.72 to 6.46) were higher in cases, but not statistically significantly so.

Conclusions

Findings were consistent with previous literature describing Indigenous populations. A small sample size and poor Indigenous identification questions make it challenging to comprehensively understand cancer risk factors and burden in Indigenous populations.

Collaborative Study Comparing Gas-Liquid Chromatographic and Chemical Methods for Quantitatively Determining Vitamin E Content of Pharmaceutical Products

A collaborative study was conducted to compare the USP XVII (Emmerie-Engel) method and three GLC methods for quantitatively determining a-tocopherol, a-tocopheryl acetate, and a-tocopheryl succinate in pharmaceutical products. Nine collaborating laboratories analyzed seven pharmaceuticals encompassing tablets, capsules, and liquids. The mean coefficients of variation were: USP method, 28.6%; GLC method A, 10.2%; GLC method B, 10.8%; GLC method C, 18.0%. GLC method A was the method of choice of those evaluated. The vitamin E analogs are extracted with n-hexane from ground tablets and capsules; liquid preparations are diluted with n-hexane or injected directly onto the GLC column. The compounds are chromatographed on an 8′ × 4 mm id glass column paeked with 5% SE-30 on 100-120 mesh silanized Gas Chrom P, operated between 270-285°C, and the carrier gas flow rate adjusted so that ∝-tocopheryl acetate appears within 23-27 min. Acetic anhydride-pyridine reaction is utilized to determine whether ∝-tocopherol or ∝-tocopheryl succinate is present in a sample, since these two analogs have similar retention times. It is recommended that GLC method A be adopted as official first action.

An integrated knowledge translation approach to develop a shared decision-making strategy for use by Inuit in cancer care: a qualitative study

Background

In relation to the general Canadian population, Inuit face increased cancer risks and barriers to health services use. In shared decision-making (sdm), health care providers and patients make health care decisions together. Enhanced participation in cancer care decisions is a need for Inuit. Integrated knowledge translation (kt) supports the development of research evidence that is likely to be patient-centred and applied in practice.

Objective

Using an integrated kt approach, we set out to promote the use of sdm by Inuit in cancer care.

Methods

An integrated kt study involving researchers with a Steering Committee of cancer care system partners who support Inuit in cancer care ("the team") consisted of 2 theory-driven phases:■ using consensus-building methods to tailor a previously developed sdm strategy and developing training in the sdm strategy; and■ training community support workers (csws) in the sdm strategy and testing the sdm strategy with community members.

Results

The team developed a sdm strategy that included a workshop and a booklet with 6 questions for use by csws with patients. The sdm strategy (training and booklet) was finalized based on feedback from 5 urban-based Inuit csws who were recruited and trained in using the strategy. Trained csws were matched with 8 community members, and use of the sdm strategy was assessed during interviews, reported as 6 themes. Participants found the sdm strategy to be useful and feasible for use.

Conclusions

An integrated kt approach of structured research processes with partners developed a sdm strategy for use by Inuit in cancer care. Further work is needed to test the sdm strategy.

Polyvinyl alcohol-coated perfluorocarbon supports for metal chelating affinity separation of a monoclonal antibody

The preparation, characterisation and testing of stable non-porous coated perfluorocarbon supports functionalised with the metal chelate, iminodiacetic acid (IDA) is described. Polyvinyl alcohol (PVA), a neutral hydrophilic polymer was esterified with perfluorooctanoyl chloride and anchored to the surface of solid perfluorocarbon particles through multiple fluorophilic interactions. The PVA-coated particles were then activated by epoxidation and coupled with IDA. The presence of surface-attached chelates was clearly demonstrated by the binding and selective desorption of Zn2+ ions. Three particulate perfluorocarbons were selected as potential starting materials and the conditions for preparation of metal chelating adsorbents optimised with respect to ease of manufacture, ligand density and binding capacity towards a monoclonal antibody known to bind to commercial Zn(2+)-IDA supports. The choice of base particle strongly influenced the ligand densities and specific binding capacities towards the monoclonal antibody that could be achieved under optimal preparative conditions. Possible ways in which these metal chelating adsorbents may be employed to recover the monoclonal antibody directly from culture vessels are discussed.

The transmural progression of the no-reflow phenomenon in globally ischemic hearts

A no-reflow phenomenon (NRP) develops in hearts subjected to global ischemia and prevents reperfusion of the subendocardial myocardium upon restoration of arterial supply. In the present study the transmural progression of the NRP across the left ventricular wall in globally ischemic rat hearts was quantitatively defined by using autoradiographic nuclear track emulsion (NTE) as an indicator of microvascular competence. Rat hearts were isolated and perfused for 10 min with oxygenated Krebs-Henseleit buffer, then were made completely globally ischemic for from 0 to 60 min and were maintained at 37 degrees C. They were then fixed by perfusion with glutaraldehyde after which NTE was injected into the coronary arteries. Transverse sections through the left ventricles were examined by scanning electron microscopy using back-scattered electron imaging and the vessels in a standard transmural contiguous series of photomicrographs were classified according to whether they did or did not permit the flow of NTE. Non-ischemic control myocardium showed a mean proportion of filled vessels of 99.4 +/- 0.5% SD, and those subjected to 15 min of ischemia showed only a slight overall reduction. After 30 min of ischemia 96 +/- 3% of vessels in the subepicardial third could be reperfused, but the proportion progressively diminished across the myocardium to total no-reflow near the endocardium. From 45-60 min of ischemia the totally non-reperfusible region remained confined to the subendocardial third but there was a significant reduction in the proportion of reperfusible vessels in the subepicardial third to 40% +/- 27%. Ischemia thus progressively reduces the capacity of myocardium to be reperfused.(ABSTRACT TRUNCATED AT 250 WORDS)

Digestion, absorption and effects on cholesterol absorption of menhaden oil, fish oil concentrate and corn oil by rats

Adult male rats were surgically provided with a drainage catheter in the left thoracic lymphatic channel and an indwelling duodenal catheter for constant infusion of physiological saline-5% glucose. After an overnight fast, animals were given a single duodenal dose of an aqueous emulsion containing one of the following: oleic acid, corn oil, menhaden oil or a fish oil concentrate (FOC) and [1,2-3H]cholesterol. Digestion and absorption were estimated by recovering the total fatty acids in the thoracic duct lymph over a 24-h collection period (after subtraction of the "baseline" endogenous fatty acids in the lymph). Cholesterol absorption in the thoracic duct lymph was significantly reduced (P less than 0.05) in the presence of menhaden oil or FOC compared to that in the presence of corn oil. With various fat feedings, the major increases in lymph fatty acids were directly related to the dietary fatty acid content. The relative amounts of eicosapentaenoic acid (EPA) and arachidonic acid (AA) in the thoracic lymph were influenced by the lipid content of the emulsion. The EPA/AA ratio in control, oleic acid and corn oil feedings ranged from 0.12 to 0.25. When marine oil was administered, the EPA/AA ratio was 0.78-0.98. The total amount of fatty acids found in the lymph after marine oil feeding was significantly less (P less than 0.01) than that found after corn oil feeding. The results suggested that the digestion and absorption of menhaden oil and FOC were decreased as compared with corn oil. The EPA/AA ratio was increased in the thoracic lymph after dietary fish oil feeding.

In vitro clearance of chylomicron triglycerides containing (omega-3) eicosapentaenoate

Rat mesenteric lymph chylomicrons, containing triglycerides enriched with either [14C]oleic acid or [14C]eicosapentaenoic acid, were prepared by ultracentrifugation of lymph samples collected for 6 h after a single duodenal infusion of an emulsion containing 0.3 mmol of either fatty acid. After determination of protein and of total fatty acid content and composition, enriched chylomicrons were suspended in Krebs-bicarbonate buffer. Non-working hearts were perfused in a recirculating system for 45 min using the enriched chylomicron preparations. At 15 min intervals during perfusion, the media were assayed for total radioactivity, 14CO2 and 14C-labeled fatty acids associated with triglycerides, unesterified fatty acids, phospholipids, mono- and diglycerides. After perfusion, the hearts were extracted and assayed for total lipid radioactivity and isotope distribution among heart lipid fractions. With this membrane-supported lipoprotein lipase system, clearances of chylomicron triglycerides containing either fatty acid were identical, as were the myocardial uptakes of the fatty acids and oxidations to 14CO2. Furthermore, except for a significantly greater incorporation of eicosapentaenoate into myocardial phospholipids, tissue isotope distributions of the two labeled fatty acids were also the same. These studies suggest that at least the initial phases of peripheral clearance of chylomicrons enriched in omega-3 fatty acids is as efficient as with those containing oleate.

Comparison of the clearances of serum chylomicron triglycerides enriched with eicosapentaenoic acid or oleic acid

Rat mesenteric lymph chylomicrons containing triglycerides enriched with either [14C]oleic acid (OA) or [14C]-eicosapentaenoic acid (EPA) were prepared by ultracentrifugation of lymph samples collected for 6 hr after a single duodenal infusion of an emulsion containing either fatty acid. These chylomicrons were injected into the jugular vein of recipient rats and, at various time intervals, blood was drawn and serum was assayed for radioactivity. In separate animals, serum lipoprotein fractions were separated by ultracentrifugation, and the redistribution of labeled fatty acid among circulating lipoproteins was determined by liquid scintillation spectrometry. When the early disappearance rates (10 min) of either total serum radioactivity or specifically the chylomicron fraction were compared, there were no differences between the groups receiving OA- or EPA-enriched chylomicrons. However, disappearance rates of EPA-enriched chylomicrons were slower than those of OA-enriched chylomicrons from 25 to 90 min. The small but significant differences in the disappearance rates for the longer time periods cannot be ascertained without further studies. At 5 min after injection of either type of chylomicron, the d less than 1.006 g/ml lipoprotein fraction of serum chylomicrons and very low density lipoproteins contained almost 90% of the original radioactivity. By 240 min, when less than 2% of the radioactivity remained, this radioactivity in the d less than 1.006 g/ml fraction was 43-46%, with concomitant increases in the low and high density lipoprotein fractions and in the lipoprotein-free serum.

Affinity purification of tetanus toxin using polyclonal and monoclonal antibody immunoadsorbents

Tetanus toxin has been immunopurified on immunoadsorbent columns derived from equine polyclonal antitoxin coupled to cyanogen bromide-activated Sepharose CL4B. Desorption of bound toxin in active form was achieved only when the immunoadsorbent was mixed with Sephadex G15 and this mixture overlaid on a further volume of Sephadex G15. With equine antibody, 64% of adsorbed toxin was recovered with a specific activity of 2400 limiting flocculation units (Lf)/mg protein N (1.2 X 10(8) minimum lethal doses (MLD)/mg protein N). Similarly prepared immunoadsorbent derived from murine monoclonal antitoxin of low affinity had improved desorption with less acidic desorbents, without the requirement for Sephadex G15; greater than 80% of adsorbed toxin was recovered with a specific activity of 3000 Lf/mg protein N (1.6 X 10(8) MLD/mg protein N).

Mass spectrometry and identification of sterols in vegetable oils as butyryl esters and relative quantitation by gas chromatography with flame ionization detection

Electron ionization mass spectrometry (MS) of sterol butyrates is described. Fragmentation of common sterol butyrates is related to structure and is discussed in relation to the fragmentation of free sterols and of commonly used sterol derivatives. Derivatized samples of vegetable oils are introduced using a 10 m capillary gas chromatographic (GC) column for complete separation of the sterol butyrates. Quantitation of sterol butyrates in vegetable oils by packed column GC/flame ionization detection is based on percent relative area of peaks identified by MS. Results of analyses of sunflower, castor, rapeseed, and virgin olive oils, and other oils are presented. These techniques have been applied to the rapid screening of marketed olive oils for possible adulteration.

Detection of vegetable oil adulteration in ice cream

This study was to demonstrate the application of various analytical methods to the detection, identification, and quantitation of vegetable oil adulteration of ice cream. Total fat content, sterols, long- and short-chain fatty acids, vitamin E, Reichert-Meissl values, and Polenske values were measured in ice cream. All methods except total fat determination were capable of detecting vegetable oil adulteration. Sterol determination was the most effective and versatile measurement because it provided information not only on the detection and extent of adulteration but also on the possible identity of the adulterant.

Intestinal absorption and lipoprotein transport of (omega-3) eicosapentaenoic acid

Adult male rats were surgically provided with a drainage catheter in the left thoracic lymphatic channel and an indwelling gastric catheter for constant infusion of saline-glucose. After an overnight fast, animals were given a single gastric dose of an aqueous emulsion containing one of the following 1-14C-labeled fatty acids: oleic, arachidonic or eicosapentaenoic acid, and [1,2-3H]cholesterol. Absorption was estimated by the appearance of radioactivity in lymph over a 24-h collection period, and the lymph lipoprotein distributions and lipoprotein lipid distribution were determined in the 24-h samples. Although there were apparent differences in the rates of eicosapentaenoic and arachidonic acid absorption, the overall appearance (after 24 h) of these acids in lymph was quantitatively equivalent to that of oleate. Furthermore, cholesterol absorption from each fatty acid medium was quantitatively similar. The distributions of each fatty acid among major lymph lipoproteins were similar with 93-95% recovered in chylomicrons and very low density lipoprotein (VLDL) fractions. Furthermore in these lipoproteins, 85-91% of each of the three fatty acids was recovered as triglycerides. With both polyunsaturated fatty acids, there was greater incorporation into phospholipids and their precursor partial glycerides than with oleate. These studies suggest that unesterified eicosapentaenoic acid is absorbed efficiently into the lymphatic system, and has lymph lipoprotein and lipid distribution comparable to those of the more typical mono- and polyunsaturated fatty acids.

Production and characterization of monoclonal antibodies to tetanus toxin

Monoclonal antibodies against tetanus toxin were produced to obtain highly specific antisera. Ten hybridoma cell lines producing monoclonal antibodies were derived from the fusion of rat myeloma cells and spleen cells from rats immunized with tetanus toxoid. Eight produced monoclonal antibodies specific for determinants on toxin and toxoid, whereas two were specific only for determinants on the toxoid. The antibodies produced by hybridomas were characterized by determination of the class of light and heavy chain components, epitope specificity, toxin neutralization, and subunit specificity. All of the antibodies contained kappa light chain, eight contained the gamma 1 heavy chain, and the remaining two contained the gamma 2a heavy chain. Five distinct epitopes were indicated by competition assay of paired monoclonal antibodies, and 4 of the 10 monoclonal antibodies neutralized the in vivo activity of tetanus toxin. The four neutralizing monoclonal antibodies and one other were specific for the C fragment of the heavy chain of the toxin molecule.

Enzymatic determination of cholesterol in egg yolk

The quantitative determination of cholesterol in egg yolk by using an enzymatic test kit is described. Cholesterol in the egg yolk is extracted with other lipid components by methylene chloride-methanol (2 + 1) and is enzymatically determined after saponification of the lipid extract. The method is relatively rapid, simple, and accurate and gives results which agree with those obtained by using a gas-liquid chromatographic (GLC) method. The mean cholesterol content of egg yolk determined by the enzymatic and GLC methods was 1237 and 1240 mg/100 g, respectively.

High pressure liquid chromatographic determination of cholesterol in foods

A high pressure liquid chromatographic method that uses the benzoate ester of cholesterol has been developed for the measurement of cholesterol in foods. A 300 x 3.9 mm id muBondapak C18 column and a variable wavelength ultraviolet detector are used with a 100% methanol mobile phase. Amounts as low as 10 ng cholesterol benzoate can be detected. The results from the analyses of a variety of foods are given and compared with results from gas-liquid chromatographic analyses. The comparison of the 2 chromatographic techniques is favorable.

Effect of dietary Lunaria oil on chick growth and organ lipid content

An experiment was conducted to determine the effects of feeding Lunaria oil to chicks. A deit containing Lunaria oil produced poorer growth and lower feed conversion than one containing corn oil. White Plymouth Rock chicks had apparent digestibility values of 89.9% and 55.8% for corn and Lunaria oil, respectively. Gas-liquid chromatographic analysis of heart, liver, and body cavity lipids (fat) showed that more erucic and nervonic acids accumulated in the fat of the birds fed Lunaria oil than in the fat of those fed corn oil.

Evidence for an immunological relationship between Streptococcus mutans and human cardiac tissue

Two-dimensional immunoelectrophoresis, indirect immunofluorescence, and radioimmunoassay were used to demonstrate that antisera from rabbits immunized with some strains of Streptococcus mutans contain antibodies that cross-react with human cardiac tissue. These rabbits were sensitized to a shocking dose of human heart antigen, and anaphylactic deaths were sometimes produced. Myocarditis was also a result of the immunization procedure. Data obtained with all five techniques were comparable. Cross-reactivity could be associated with three antigens designated ID, IF, and HL. Antigens ID and IF were major immunogens of S. mutans Ingbritt, but HL antibodies were produced only after hyperimmunization. Corss-reactivity was of an immunological nature and not the result of nonspecific factors such as bacterial Fc reactive components or antibody elicited to growth medium constituents. These findings support the hypothesis that immunization with S. mutans can induce autoimmune reactions and indicate that antigens must be selected with caution before formulating any dental caries vaccine.

Collaborative study of a GLC method for vitamin E

The official GLC method of the Association of Official Analytical Chemists (AOAC) for determining vitamin E was modified and collaboratively studied for the National Formulary (NF). The internal standard hexadecyl hexadecanoate (cetyl palmitate) was substituted for the dotriacontane used in the AOAC method, and some other minor changes were made. Eleven samples, representing all types of NF formulations and NF bulk materials, were analyzed by 11 laboratories. The coefficients of variation of the reproducibility and repeatability were 4.5 and 2.4%, respectively, for all laboratories and samples. The values were 3.4 and 1.6%, respectively, when the one laboratory statistically determined to be an outlier was excluded. The coefficients of variation of reproducibility and repeatability for alpha-tocopheryl acid succinate were 2.1 and 1.5%, respectively. All of these values lie within the 5% limit required by the NF.

Gas-liquid chromatographic determination of cholesterol and other sterols in foods

A gas-liquid chromatographic (GLC) method, using the butyryl esters of sterols, has been developed for the measurement of cholesterol, stigmasterol, sitosterol, and campesterol in foods. An immobile phase of 1% SE-30 coated on 100-120 mesh Gas-Chrom Q packed in a 6 inch X 4 mm id glass column operated at 255 degrees C was the most satisfactory of 7 column packings evaluated. Extraction with chloroform-methanol gave 98.7% recovery with a coefficient of variation of 1.8% for cholesterol added to a variety of foods. When cholesteryl palmitate was added to vegetable oil and the butyryl derivative was prepared, followed by GLC analysis, the recovery was 99.3% with a coefficient of variation of 0.9%. Amounts as low as 1 mg/100 g food can be detected with a precision of 2.5%. The results of the analysis of a variety of foods for cholesterol, campesterol, sitosterol, and stigmasterol are given.

Butyl ester preparation for gas-liquid chromatographic determination of fatty acids in butter

Butter oil is extracted from butter with hexane, using a rolling boil technique. The resulting 10% butter oil in hexane is converted to butyl esters, using butanol in place of methanol as specified in the official final action method, 28.063-28.067. A water wash and centrifuge technique is used to remove butanol from the n-hexane-butyl ester solution. Conversions to butyl esters are quantitative by the boron trifluoride, sulfuric acid, and sodium butoxide procedures. When methyl ester methods are used, there are serious losses of the short chain volatile and water-soluble acids, making the methyl ester procedures questionable for determining the authenticity of milk fat.

Collaborative Study of the Gas-Liquid Chromatographic Assay for Vitamin E

A collaborative study for the analysis of vitamin E in multivitamin tablets was conducted and the method was subsequently approved as official first action by the AOAC. Additional data were obtained by an extensive collaborative study sponsored by the Pharmaceutical Manufacturers Association, which verified the usefulness of GLC for the assay of α-tocopherol, α-tocopheryl acetate, and α-tocopheryI acid succinate. The mean coefficient of variation obtained from the 8 participating laboratories for duplicate samples, duplicate injections, was ±2.04, 1.75, and 2.71%, respectively. Further collaborative studies were conducted on samples of mixed tocopherol concentrate, multivitamin tablets, and multivitamin soft gelatin capsules. The mean coefficient of variation obtained from 13 collaborators was in the range of ±5%. The accumulated data demonstrate the utility of this technique for improved specificity and reliability of the analysis of vitamin E.

Comparison of Gas-Liquid Chromatographic and Chemical Methods For Quantitative Determination of the Menadione and Menadione Sodium Bisulfite Content of Pharmaceutical Products

A collaborative study was conducted to compare the NF XII method and a GLC method for quantitatively determining menadione in pharmaceutical products. Ten collaborating laboratories analyzed 6 Pharmaceuticals encompassing tablets, capsules, and a liquid. Menadione is extracted with diethyl ether from ground tablets; slip capsules are opened and the contents are emptied into the ether along with the capsule parts. After filtration and removal of the ether, the residue is redissolved in n-hexane. The menadione sodium bisulfite injectable is transferred to a separatory funnel and extracted with chloroform and sodium hydroxide, evaporated to dryness, and redissolved in n-hexane. Menadione is chromatographed on a 6’ × 3mm id glass column packed with 1% neopentyl glycol succinate on 100–120 mesh Gas Chrom Q and operated at 135°C. The carrier gas flow is adjusted so that menadione appears within 5.5–6.5 mhi. Because of the coefficients of variation, additional study is recommended.

Collaborative Study of a Chemical Method for Calcium Pantothenate

A chemical method for determining calcium pantothenate in pharmaceutical preparations has been studied collaboratively. The pantothenate molecule is cleaved with acid, and the resulting β-alanine is treated with a chlorinating solution and then with potassium iodide. The free iodine is measured spectrophotometrically at 358 mμ. The average coefficient of variation for all samples studied collaboratively is 8.9%. The method is recommended for adoption as official first action.

Separation of Vitamins D2 and D3 as Isotachysterols D2 and D3 by Gas-Liquid Chromatography

A method for the quantitative determination of 0.5—20 μg vitamins D2 and D3 by gas-liquid chromatography is described. Vitamins D2 and D3 are completely isomerized to their respective isotachysterol isomers by acetyl chloride as demonstrated by ultraviolet and infrared absorption data. Dihydrotachysterol D2, isotachysterol D2, and isotachysterol D3 are completely resolved with a 3% JXR on 100-120 mesh Gas Chrom Q column packing. Calibration studies show that each compound exhibited a characteristic dose-response plot. Therefore, one isomer cannot be used as a direct internal standard for the quantitative measurement of the other isomer.

Gas-Liquid Chromatographic Method for the Determination of Fat-Soluble Vitamins. VI. Application to Pharmaceuticals Containing Menadione

Gas-liquid chromatography has been used to quantitatively determine menadione (vitamin K3) in pharmaceuticals, using a 1% neopentyl glycol succinate column and a hydrogen flame detector. The gas chromatographic measurements compare favorably with results by the National Formulary methods on the same samples.

Determination of Saturated and Unsaturated Fatty Acids: Comparison of Gas-Liquid Chromatographic, Thiocyanogen Number, and Lead Salt-Ether Methods

The weight per cent composition of the C16—Cis series of fatty acids in edible vegetable oils was determined by GLC, lead salt-ether, and thiocyanogen number methods. Total saturated and unsaturated fatty acid percentages obtained by GLC and the lead salt-ether methods were in poor agreement; the lead salt-ether unsaturated fatty acid percentages tended to be higher than the GLC values. The thiocyanogen number values for unsaturation were higher than GLC values lor every fat and oil analyzed except one. The polyunsaturated fatty acid percentages obtained by the thiocyanogen number method were not similar to the GLC values for about half of the fats and oils examined.

Gas-Liquid Chromatography of Vitamin B6 (Pyridoxal, Pyridoxol, and Pyridoxamine) and Its Application to Pharmaceuticals Containing Pyridoxol

A gas chromatographic procedure has been developed for the determination of pyridoxal, pyridoxol, and pyridoxamine. These compounds are first converted to their acetyl derivatives and then injected into the gas chromatograph. The acetyl derivatives are formed by the interaction of the vitamin B6 analogs with acetic anhydride in the presence of a catalyst, extracted with a suitable organic solvent, and separated by gas chromatographic techniques. Results were confirmed by infrared, ultraviolet, nuclear magnetic resonance, and mass spectrometry. This technique has been successfully used to quantitatively measure the pyridoxol content of pharmaceutical products

Gas-Liquid Chromatographic Method for Determination of Fat-Soluble Vitamins. III. Evaluation of a Vacuum Distillation Procedure for Vitamin E Isolation, Using C-14 Labelled Alpha-Tocopheryl Acetate

Alpha-tocopheryl acetate, carbon-14 labelled in the methyl group at the two position, was used to determine the stability and recovery of the vitamin during vacuum distillation (140–160°C, and 0.020 mm Hg pressure, 60 minutes). Evaluation was based on measurements of radioactivity with a liquid scintillation spectrometer and a lowbackground Geiger counter. Recoveries of 20 mg of the pure compound were nearly quantitative (97%). Recoveries of the tocopheryl ester added to lard, “stripped” of vitamin E, at 0.5 mg/g or less and to butter at 0.1 mg/g were 98 and 82%, respectively. Results of the differential counting technique suggest that the ester is increasingly unstable at temperatures exceeding 160° and that a molecular rearrangement probably takes place.

Evaluation of Four Stock Diets for Liver Lipid Research on Rats. II. Fatty Acid Patterns of Total Lipid Extracts

Fatty acid patterns of total liver lipid extracts were determined for groups of young rats fed ad libitum on four different diets. The diets were both of natural and semisynthetic composition in which fat content was 3.6–5.5%. Animals were supplied with diet at weaning and sacrificed after 3 weeks. The results indicate that the liver fatty acid patterns were independent of the dietary fatty acid patterns. However, significant differences in liver fatty acid patterns resulting from the feeding of the different diets were observed for hexadecanoate, 9-octadecenoate, 9,12-octadecadienoate, 9,12, 15-octadecatrienoate, eicosanoate, and decosanoate. No significant differences were observed for 5,8,11,14-eicosatetraenoate regardless of the diet fed.

Evaluation of Four Stock Diets for Liver Lipid Research on Rats. I. Influence of Diet on Body Weight and Liver Composition

Four rations have been fed to weanling male albino rats for 14 and 21 days. The rations contained from 3.6 to 5.5% crude fat and ranged in fiber content from 0.1 to 6.0%. The rations were evaluated in terms of liver lipids, liver weight, feed efficiency, and average daily gains. The experiment was litter-mated across treatments. Significant ration effects on total lipids, phospholipids, free cholesterol, and average daily gain were observed after 21 days of feeding a low fiber, 19.1% crude protein, 5.1% crude fat, semisynthetic ration.

Evaluation of an Improved Sublimation Apparatus Utilizing Carbon-14 Labeled Methyl Esters of Fatty Acids

An improved sublimation appparatus has been designed and tested. The unit was tested with carbon-14 labeled methyl esters of fatty acids up through 22 carbon chain length. Samples of 40 mg or less of mixed fatty acid methyl esters can be sublimed routinely with recoveries of approximately 100%.