Comparison of physicochemical and functional properties of duck feet and bovine gelatins

BACKGROUND

Previous studies have indicated that duck feet are a rich source of gelatin extractable from avian sources. In this study, the physicochemical and functional properties of avian gelatin extracted from duck feet (DFG) with acetic acid were compared with those of commercial bovine gelatin (BG).

RESULTS

The yield of DFG obtained in this study was 7.01 ± 0.31%. High-performance liquid chromatography analysis indicated that the imino acid content was slightly lower for DFG compared with BG (P < 0.05). Differences in molecular size and amino acids between DFG and BG were also observed. The isoelectric points of DFG and BG were at pH 8 and 5 respectively, and the overall protein solubility of BG was higher than that of DFG. Gels prepared from BG exhibited higher bloom strength, viscosity and clarity and were darker in colour compared with DFG gels (P < 0.05). The gelling and melting points of BG were 21.8 and 29.47 °C respectively, while those of DFG were 20.5 and 27.8 °C respectively. BG exhibited slightly better emulsifying and foaming properties compared with DFG.

CONCLUSION

Although some differences between DFG and BG were observed, the disparities were small, which indicates that DFG could be exploited commercially as an alternative source of gelatin. © 2016 Society of Chemical Industry.

Bone selective protective effect of a novel bone-seeking estrogen on trabecular bone in ovariectomized rats

The drawbacks of estrogen restrict the clinical use of hormone replacement therapy, and it would be most helpful to explore new estrogenic substances that could prevent bone loss and be free from any adverse effects. We synthesized a new compound named bone-seeking estrogen (SE2) by combining 17β-estradiol (E2) with iminodiacetic acid through the Mannich reaction. E2 and SE2 were labeled with isotope (3)H, and the tissue distribution tests of E2-(3)H and SE2-(3)H were analyzed by the radioactivity. The specific nuclear binding of E2 and SE2 in osteoblasts was measured. SE2 exhibited significantly greater affinity for bone but lower affinity for ovary and uterus than did E2, and SE2 maintained a high affinity for the estrogen receptor alpha similar to that of E2. SE2 administration did not induce uterine hypertrophy. Body weight increase was significantly suppressed by treatment with E2 but not by SE2 after ovariectomy (OVX). SE2 decreased bone turnover as E2 after OVX detected by serum biochemical markers. Bone histology and micro-CT analysis revealed that SE2 administration, similar to E2, could improve bone mass and trabecular architecture after OVX. Biomechanical analyses showed that SE2 treatment effectively increased mechanical properties after OVX. The results suggested that SE2 was effective in preventing OVX-induced bone loss and exhibited few side effects on body weight and uterine hypertrophy, which was beneficial in reducing the adverse effects caused by E2. SE2 may be a better choice than E2 for the prevention of postmenopausal osteoporosis.

State diagram of salmon (Salmo salar) gelatin films

BACKGROUND

A state diagram presents different physical states of a biomaterial as a function of solid content and temperature. Despite their technological interest, little information is available on protein systems such as gelatin/water mixtures. The objective of this work was to develop state diagrams of salmon gelatin (SG) and bovine gelatin (BG) in order to determine maximal freeze concentration parameters (T'(g) , T'(m) and X(s') ) and to relate possible differences to their biochemical characteristics.

RESULTS

Biochemical characterisation of SG showed lower molecular weight and iminoacid concentration compared with BG. Likewise, the glass transition temperature (T(g) ) was lower for SG at X(s) > 0.8, which was associated with its lower molecular weight. Unexpectedly, the depression of freezing temperature (T(f) ) was greater for SG at X(s) > 0.1, which was associated with its higher ash content. Isothermal annealing produced effective values of T'(g) ≈ - 52 °C, T'(m) ≈ - 46 °C and X'(s) ≈ 0.6 for both gelatins. Interestingly, the enthalpy change associated with T'(m) (ΔH T m) was significantly higher for SG than for BG after annealing, indicating a higher proportion of ice present at about - 50 °C.

CONCLUSION

Maximal freeze concentration parameters were similar between the two gelatins, though differences in biochemical properties were evident. The results show that there are likely different ways of interaction of SG and BG with water.

Extraction and characterisation of pepsin-solubilised collagens from the skin of bigeye snapper (Priacanthus tayenus and Priacanthus macracanthus)

BACKGROUND

Fish collagen has been paid increasing attention as an alternative to the mammalian counterpart owing to the abundance of fish skin as a processing by-product. Generally, the low yield of collagen extracted using the typical acid solubilisation process has led to the use of mammalian pepsin as an aid for increasing the yield. Alternatively, fish pepsin, especially from tuna stomach, can be used for the extraction of pepsin-solubilised collagen (PSC). Therefore the objective of this study was to extract and characterise PSC from the skin of bigeye snapper, a fish widely used for surimi production in Thailand.

RESULTS

PSCs from the skin of two species of bigeye snapper, Priacanthus tayenus and Priacanthus macracanthus, were extracted with the aid of tongol tuna (Thunnus tonggol) pepsin and porcine pepsin. PSCs from the skin of both species extracted using porcine pepsin had a higher content of beta-chain but a lower content of alpha-chains compared with those extracted using tuna pepsin. All PSCs contained glycine as the major amino acid and had an imino acid (proline and hydroxyproline) content of 189-193 residues per 1000 residues. Transition temperatures of PSCs were in the range 30.6-31.3 degrees C. Fourier transform infrared spectra revealed some differences in molecular order between PSCs extracted using porcine pepsin and tuna pepsin. Nevertheless, the triple-helical structure of PSCs was not affected by pepsin digestion. Zeta potential analysis indicated that PSCs from P. tayens and P. macracanthus possessed zero net charge at pH 7.15-7.46 and 5.97-6.44 respectively.

CONCLUSION

Tongol tuna pepsin could be used as a replacement for mammalian pepsin in PSC extraction. However, a slight difference in PSC properties was found.

Dinitrophenyl derivatization of imino acids, spectral characteristics and HPLC analysis: application in urinary peptide-derived hydroxyproline and proline assay

Background: Assay of urinary imino acids, in particular peptide derived, is of immense utility in diagnosis of collagen-related disorders. The often-used methods for hydrolysis of urinary peptides need a long time and are cumbersome, hence the need for relatively simpler, but effective methods.

Methods: The method described, based on alkaline hydrolysis by autoclaving for 60 min followed by pre-column dinitrophenyl (DNP) derivatization and high-performance liquid chromatography (HPLC) analysis, demonstrates the complete hydrolysis and stability of urinary peptide derived imino acids.

Results: DNP derivatives of both imino acids had identical λ max (380 nm) with molar &epsi; of 28.224 x 103 and 17.036 x 103, respectively, for hydroxyproline (Hyp) and proline (Pro). HPLC run, extending up to 18 min, resolved major components of collagen products, namely Hyp, Hyl, Gly, Pro and Lys, with retention times of 6.5, 9.8, 10.5, 11.2 and 12.55 min, respectively. The assay method conformed to linear response for individual amino acid concentrations of 0.5-4.0 nmol per injection, with goodness of fit ( r2 value) 0.99 for both Hyp and Pro, and detection limit of 0.05-4.0 nmol of DNP derivatives. The recovery of Pro and Hyp, when spiked with urine prior to hydrolysis, were found to be 95% and 92%, respectively.

Conclusion: Alkaline hydrolysis by autoclaving and DNP derivatization of imino acids followed by HPLC provides a method for the analysis of peptide-derived Hyp and Pro in urine. Hence, it is of utility to study collagen disorders.

Magnetic IDA-modified hydrophilic methacrylate-based polymer microspheres for IMAC protein separation

Preparation of a new type of magnetic non-porous poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate) microspheres with hydrophilic properties containing coupled iminodiacetic acid (IDA) is described. The prepared microspheres were used for the immobilization of Ni(II) or Fe(III) ions to show their application in protein binding studies. Human IgG was bound to magnetic Ni(II)-IDA-modified microspheres and conditions of its adsorption and elution were optimized. Non-specific binding of the protein to magnetic microspheres in the absence of Ni(II) ions was low. Fe(III) ions immobilized on magnetic IDA-modified microspheres were used for the specific binding of porcine pepsin, as a model phosphoprotein. The ability of phosphate buffer to release the adsorbed enzyme from the microspheres and a low adsorption of the dephosphorylated protein indicate the participation of phosphate groups in the pepsin interaction. The elaborated method represents a rapid technique that can be used not only for the separation of proteins but also for analytical purposes.

Investigation of mechanisms of oxidation of EDTA and NTA by permanganate at high pH

Permanganate has been used for oxidation of nuclear wastes containing chelating agents such as ethylenediaminetetraacetic and nitrilotriacetic acids (EDTA and NTA) to improve separation of radionuclides and heavy metals from the wastes, butthe mechanisms of degradation of these and related organic ligands at high pHs have not been studied. EDTA, NTA, and the model compound ethylenediamine (EN) were found to be readily oxidized by permanganate at pH 12-14. The reduction of permangante was accompanied by formation of unstable manganate and dispersed MnO2 particles, which constituted the final product of permanganate reduction. The yields and speciation of EDTA, NTA, and EN breakdown products were affected by the pH and permanganate dose. Iminodiacetic acid (IDA), oxalate, formate, and ammonia were the predominant EDTA and NTA oxidation products. Mineralization of EDTA, NTA, and EN to CO2 was more significant at pH 12. At pH 14 formation of oxalate and deamination to NH3 were the most important reactions. IDA was released upon the oxidation of both EDTA and NTA, but EDTA oxidation yielded no ethylenediaminediacetic acid (EDDA). The speciation of the reaction products indicated that the ethylene group in EDTA was the preferred attack site in oxidations by alkaline permanganate.

HPLC method for determination of the purity of a mebrofenin-ligand for 99mTc-complexes

A reversed-phase HPLC method has been developed for the estimation of purity and quantitative determination of mebrofenin UV detection at 205 nm was used. The stability of mebrofenin alone and in the presence of stannous chloride at 25 degrees C was studied. No decomposition product was found and there was no influence of SnCl2 on the stability of mebrofenin.

High-performance liquid chromatographic enantioseparation of unusual secondary amino acids on a D-penicillamine-based chiral ligand exchange column

The application of a chiral ligand-exchange column (CLEC) for the direct high-performance liquid chromatographic enantioseparation of unusual secondary amino acids using D-penicillamine-Cu(II) complex as chiral selector is reported. The amino acids investigated were pyrrolidine-2-carboxylic acid, piperidine-2-carboxylic acid, piperazine-2-carboxylic acid, morpholine-3-carboxylic acid, and thiomorpholine-3-carboxylic acid analogs. Chromatographic results are given as the retention, separation, and resolution factors. The chromatographic conditions were varied to achieve optimal separation. The elution sequence of the enantiomers was determined and in most cases the S isomer eluted before R.

SclC is a member of a novel family of collagen-like proteins in Streptococcus equi subspecies equi that are recognised by antibodies against SclC

Previously we have reported on a cell surface collagen-like protein, called SclC, from Streptococcus equi subspecies equi. In the present study we show that this protein is a member of a family of seven collagen-like proteins, called SclC-SclI in this subspecies. All proteins contain an N-terminal signal sequence, followed by a unique non-repetitive region called A, a highly repetitive collagen-like region (CL) consisting of Glycine-Xaa-Yaa-triplet repeats. Following the CL-region a C-terminal proline-rich putative wall spanning region (W) preceding an LPXTG-motif and a hydrophobic transmembrane region (M) are found, typical features of cell surface exposed proteins in Gram-positive bacteria. The nucleotide and amino acid sequences, were analysed to investigate the similarities between them, and recombinant proteins encoding different domains (A- and CL-regions) were expressed and purified. Although the novel collagen-like proteins display differences in amino acid sequences, affinity purified antibodies against SclC were found to cross react with the other members of the novel collagen-like proteins. Furthermore, in sera from horses previously diagnosed having strangles, antibodies against these proteins were detected suggesting that these proteins are expressed during the infection.

Alternative quality control for technetium-99m IDA complexes

A quality control procedure for 99mTc-IDA complexes based on the use of C18 Sep-pak cartridges is developed and the validation of the procedure presented. C18 Sep-pak cartridges are pretreated by washing with 95% ethanol followed by 10(-3) N hydrochloric acid. A small amount of the 99mTc-IDA complex is applied, washed with 10(-3) N hydrochloric acid and eluted with 95% ethanol. The radiochemical purity values obtained for 99mTc-mebrofenin and 99mTc-disofenin using this Sep-pak procedure are comparable to those obtained using the standard two strip (ITLC-SG/100% methanol, ITLC-SA/20% saline) procedure.

Quantification of duodenogastric reflux in patients with choledochoduodenostomy

BACKGROUND

Frequently, patients present with symptoms after cholecystectomy (pain or discomfort in the upper part of the abdomen, postprandial fullness, bile vomiting, among others). Duodenogastric reflux has been associated with these symptoms in some patients. Therefore, this study was done to investigate this relationship.

STUDY DESIGN

We evaluated duodenogastric reflux (DGR) in ten healthy patients, in ten patients who had asymptomatic simple cholecystectomy, in ten patients who had asymptomatic cholecystectomy with supraduodenal choledochoduodenostomy (CD), and in ten patients who had cholecystectomy plus CD followed by discomfort in the upper abdomen, postprandial fullness and bile vomiting, but no colicky pain or acute cholangitis. Duodenogastric reflux was quantified using continuous intravenous infusion of technetium-99m labeled hepatoiminodiacetic acid (99mTc-HIDA) and subsequently determining its concentration in gastric juice.

RESULTS

All of the patients who underwent operation, whatever the technique used, had higher reflux rates than those in the control group (p < 0.001). Moreover, reflux rates were comparable in the patients who underwent simple cholecystectomy compared with patients in the asymptomatic cholecystectomy plus CD group. Conversely, when patients with cholecystectomy plus CD presented with discomfort in the upper part of the abdomen as well as bile vomiting, they had higher reflux rates than patients who underwent simple cholecystectomy (p < 0.001) and asymptomatic patients with associated CD (p < 0.001).

CONCLUSIONS

Our results suggest that DGR must be involved in the genesis of these dyspeptic symptoms.

Duodenogastric reflux quantification in peptic ulcer surgery: comparison between different surgical techniques

BACKGROUND

We quantified duodenogastric reflux with 6-hour continuous intravenous infusion of technetium 99m-labeled hepatoiminodiacetic acid (99mTc-HIDA) and subsequent quantification in gastric juice.

METHODS

For this purpose, 50 patients were studied who had undergone surgery on the stomach with different surgical techniques: bilateral vagotomy plus Heineke-Mikulicz pyloroplasty, bilateral truncal vagotomy plus anterior pylorectomy, proximal gastric vagotomy, antrectomy and Billroth I reconstruction, and antrectomy and Billroth II reconstruction, comparing them with 10 healthy subjects used as a control group. We also studied the existing correlation between the rates of reflux determined by 99mTc-HIDA and those of total bile acids in gastric juice.

RESULTS AND CONCLUSIONS

Patients who underwent gastric surgery had significantly greater quantities of duodenogastric reflux (p < 0.001) than had the control group. When the groups undergoing gastric surgery were compared, the patients who underwent resection showed higher reflux rates (p < 0.001) than did the patients who did not undergo resection. We found no differences among the groups of patients who did or did not undergo resection. We also found a highly significant correlation (p < 0.001) between the concentrations of 99mTc-HIDA and bile acids in gastric juice.

Efficient enantioselective separation and determination of trace impurities in secondary amino acids (i.e., imino acids)

An R-(-)-1-(1-naphthyl)ethyl carbamoylated-beta-cyclodextrin bonded phase in conjunction with a nonaqueous polar mobile phase was used for the highly selective enantioseparation of a number of secondary amino acids after their pre-column derivatization with 9-fluorenylmethyl chloroformate (FMOC). Under the conditions employed, the FMOC reagent served to "lock" the imino acid into their existing conformation thereby preventing the possibility of racemization. Furthermore, it served to increase the sensitivity to the point that trace level enantiomeric impurities were easily detected. Compared with separations that use traditional reversed-phase solvents, this method showed several advantages: higher selectivity towards the imino acid enantiomers investigated, shorter analysis times, faster equilibration of the column, more stable baseline and more sensitive fluorescence detection. The detection limits for FMOC derivatives of proline, trans-4-hydroxyproline, cis-4-hydroxyproline, pyroglutamic acid, 3,4-dehydroproline, thiaproline, penicillamine acetone adduct and pipecolic acid are in the low femtomole range. The method was used for evaluation of enantioselectivity of a number of "optically pure" commercial imino acid standards. Enantiomeric impurities as low as 0.0001% (1 ppm) can be determined in some cases. High precision determination of trace levels of D-imino acids in the presence of large amounts of corresponding (opposite) L enantiomer at 1, 0.1, 0.01% and below are demonstrated.

Liquid chromatographic analysis of amino and imino acids in protein hydrolysates by post-column derivatization with o-phthalaldehyde and 3-mercaptopropionic acid

A method for the simultaneous determination of imino and amino acids is reported. The method, based on the derivatization of amino acids, separated by ion-exchange chromatography, by reaction with alkaline hypochlorite and o-phthalaldehyde-3-mercaptopropionic acid, increases the sensitivity towards imino acids to the picomole level. The use of 3-mercaptopropionic acid gives intensely fluorescent derivatives and improves the stability of primary and secondary amino acid fluorophores towards oxidation. The accuracy and reproducibility of the method are increased by using three internal standards. The determination of all amino and imino acids present in protein hydrolysates, including tryptophan, in a single run is demonstrated.

Indirect spectrophotometric determination of BIDA, DISIDA, DTPA and MDP in labelled compounds

N-(4-(n-butyl)-acetanilide)iminodiacetic acid (BIDA), N-(2,6-diisopropylacetanilide)iminodiacetic acid (DISIDA), diethylenetriaminepentaacetic acid (DTPA) and methylene diphosphonic acid (MDP) are used in labelling kits. The contents of BIDA, DISIDA or MDP of the 99mTc-labelled compounds can be determined (indirectly) spectrophotometrically with copper, eriochrome cyaanine R (ECC) and dodecylethyldimethylammonium bromide (DEDA) in a sodium barbital buffered system at pH 8.5. The calibration curves obey Beer's Law from 0 to 40 micrograms/25 mL for BIDA and DISIDA, 0 to 60 micrograms/25 mL for DTPA and 0 to 100 micrograms/10 mL for MDP.

[Isomerism of imino acids in collagen peptides]

Trans/cis ratio of X-Hyp bonds in collagen peptides was determined by chemical shifts of C gamma Hyp in 13C. n. m. r. spectra. 44% of bonds in the cis form was found in human aortic collagen of the patient with idiotia. Probably, it was the result of molecular pathology of collagen during this disease.

Postcolumn fluorometric detection system for liquid chromatographic analysis of amino and imino acids using o-phthalaldehyde/N-acetyl-L-cysteine reagent

A high-performance liquid chromatographic system for the determination of amino acid and imino acid was developed using a two-step reaction with sodium hypochlorite and o-phthalaldehyde/N-acetyl-L-cysteine (OPTA/AcCys) reagent. This reagent improved the sensitivity in the analysis of proline presumably because the fluorophore is more stable to hypochlorite which has been used for the oxidative cleavage of the imino linkage. The use of OPTA/AcCys facilitated the detection of imino acids at the same concentration level as that of amino acids. The detection limit for all the amino and imino acids was a few picomoles. This detection system, together with cation-exchange chromatographic separation, was applied to the determination of amino and imino acids in biological samples.

Determination of nitrogen and protein content of meat and meat products

Chemical and instrumental methods for determination of nitrogen and protein are reviewed for their mode of action and utility in analysis of meat proteins and products. Although the Kjeldahl digestion method is satisfactory for determining total nitrogen, it is imprecise for determining total protein content. Presence of variable amounts of nonprotein nitrogenous components and of connective tissue proteins such as collagen and elastin produces error if the formula (N X 6.25) is used to calculate crude protein. Such fibrous proteins have higher nitrogen levels (over 18%) than other muscle proteins (about 16%), and a higher than actual protein value will be determined unless a lower conversion factor is used to correct for their content. To determine meat protein content more accurately, a combination of Kjeldahl determination with one or more additional tests to correct for nonprotein and fibrous protein content is recommended. The choice of the additional method(s) is based on the user's requirement for protein characterization, available time, type of meat product, and sample size.

1,4-Thiomorpholine-3,5-dicarboxylic acid, a novel cyclic imino acid detected in bovine brain

Gas-liquid chromatography of enriched bovine brain extract revealed the occurrence of several sulfur-containing compounds. By co-chromatography with authentic product and by mass-spectrometric analysis, one of these compounds has been identified as 1,4-thiomorpholine-3,5-dicarboxylic acid (TMDA). The possible derivation of TMDA from lanthionine is discussed. This represents the second S-containing cyclic amino acid so far discovered in a mammalian brain whose physiological significance has not yet been explored.

Influences of metal ions on the reaction of amino and imino acids with fluorogenic reagents

When a twofold excess of metal ions (Cu2+, Ni2+, Zn2+, Mg2+, Ca2+, Fe3+, and Al3+) was added to a reaction medium of amino acids (1-50 microM each) with the fluorogenic reagents NBD-F (4-fluoro-7-nitrobenzo-2-oxa-1,3-diazole), DNS-Cl (5-N,N-dimethylaminonaphthalenesulfonyl chloride), OPA (o-phthalaldehyde), and fluorescamine (4-phenylspiro[furan-2(3H),1'-phthalan]-3,3'-dione), a reduction of derivatization was observed. The effect was especially marked on the reaction with NBD-F. The derivatization of His and Asp with DNS-Cl and fluorescamine and of His with OPA was suppressed by Cu2+ and/or Ni2+. The suppression by the metal ions can be overcome by the addition of EDTA to the reaction medium. For determination of a small amount of amino and imino acids (less than microM) the addition of a chelating reagent to biological samples is recommended before derivatization with these electrophilic reagents.

Imino acid and related alicyclic amine levels in biological fluids

Imino acid and related alicyclic amine concentrations in blood and urine of mammals including humans were concurrently determined by a selected ion monitoring technique. Nanomole levels of proline and pipecolic acid, and pyrrolidine and piperidine as well, were found in human urine. Proline levels but not pipecolic acid levels were higher in blood of humans than in urine. Pyrrolidine and piperidine levels in blood of humans were picomole levels and much lower than those in urine. Similar tendencies were also recognized when these 4 compounds were analyzed using animal blood and urine, although the levels were generally higher in animals than in humans. Significantly high concentrations of the imino acids and the amines were found also in animal semen.

Concentration of 99mTc-HIDA and iopanoic glucuronide by the gallbladder

To determine the ability of the gallbladder to concentrate Technetium 99mHIDA, both HIDA and iopanoic glucuronide were introduced directly into ligated gallbladders of anesthetized dogs. Serial bile samples were drawn to measure the concentration of each agent over a three hour period. Both biliary imaging agents were concentrated by the normal gallbladder. The results suggest that 99mTc-HIDA may be useful to study the gallbladder mucosal function of concentrating capacity in patients at risk for kidney damage by the standard cholecystographic agents like iopanoic acid.

The investigation of radiopharmaceutical components by fast atom bombardment mass spectrometry: the identification of Tc-HIDA and the epimers of Tc-CO2DADS

The nature of two technetium-labeled radiopharmaceutical components has been established by means of fast-atom-bombardment mass spectrometry (FABMS) in combination with carrier-added (CA) and no-carrier-added (NCA) reversed-phase high-pressure liquid chromatography (HPLC). Negative-ion FABMS was used to determine that the epimers of Tc-CO2DADS are the oxo[N,N'-(1-carboxyethylene)-bis-(2-mercaptoacetimido)]technetate(V) ions; positive-ion FABMS showed that Tc-HIDA is bis[N-(2,6-dimethylphenyl-carbamoylmethyliminodiaceto]technetate(III).

Rapid miniaturized chromatography for Tc-99m IDA agents: comparison with gel chromatography

Miniaturized chromatography systems for determining free pertechnetate and hydrolyzed reduced 99mTc levels in commercial 99mTc-labeled iminodiacetate (IDA) hepatobiliary radiopharmaceuticals were evaluated and the results compared with gel chromatography column scanning (GCS). Commercial IDA agents were evaluated including 2,6-dimethyl IDA, p-isopropyl IDA, p-butyl IDA, and 2,6-diisopropyl IDA. Of all the chromatography systems evaluated, only Gelman ITLC-SA with 20% NaCl and Gelman ITLC-SG with distilled water correlated with GCS in evaluating free pertechnetate and hydrolyzed reduced 99mTc levels for all IDA radiopharmaceuticals. The miniaturized chromatography procedure, as outlined, is rapid, taking less than 4 min, and can easily be incorporated into the daily quality control program in any nuclear medicine facility.

Quantitative temporal analysis of 99mTechnetium p-isopropyl-iminodiacetic acid (PIPIDA) as a measure of hepatic function in health and disease

Excretory liver function was analyzed in 10 healthy volunteers and 28 subjects with acute or chronic liver injury following intravenous administration of 99mtechnetium p-isopropyl iminodiacetic acid. Hepatobiliary transit of this agent was quantitated at 5-min intervals for a total of 60 min. Indices of total liver activity, liver cell uptake, liver parenchymal clearance, and bile duct clearance of 99mtechnetium p-isopropyl iminodiacetic acid were calculated from time--activity curves over heart, liver, extrahepatic bile ducts, and gallbladder. Seven subjects with acute viral hepatitis, 15 with extrahepatic biliary obstruction, and 6 with intrahepatic cholestasis were evaluated. Compared with healthy volunteers, a significant (p less than 0.0001) reduction in total liver activity and liver parenchymal clearance was demonstrated in all patient groups. Major resolution in all liver-derived indices, particularly total liver activity, occurred during convalescence from hepatitis and after biliary drainage. Nonmeasurable bile duct clearance always indicated a diagnosis of extrahepatic obstruction in cholestatic subjects, and this index normalized in subjects following biliary drainage. Whereas visual assessment of 99mtechnetium p-isopropyl iminodiacetic acid scans provided limited, useful information about the functional status of the liver, quantitative temporal analysis proved to be a much more effective technique.

HPLC analysis of Tc-99m iminodiacetate hepatobiliary agents and a question of multiple peaks: concise communication

The application of high-performance liquid chromatography (HPLC) to Tc-99m-labeled iminodiacetate hepatobiliary agents is described. The method is sensitive to variations of phenyl ring structure and give different retention times for the different agents. Technetium-99m-labeled N-(2, 6-diethylacetanilide)iminodiacetate from different sources had two components in differing amounts. It was determined that the second component, which is minor at pH above 6, is major when prepared at pH 4.5 or less. Raising the pH results in rapid conversion of the second component into the first. This observation was demonstrated also in plasma and would be expected to occur when the radiopharmaceutical is injected intravenously. The kinetics of appearance of the preparations in the bile when prepared at pH 4 and pH 6 were essentially the same.

The preparation and composition of HIDA

The compositions of four "brands" of Tc-HIDA-dimethyl HIDA (Sorin Biomedica), diethyl HIDA (Solco), diethyl HIDA (The Radiochemical Centre), and para-butyl HIDA (Sorin Biomedica)--were investigated at varying times after their preparation from "instant kits", by using Sephadex gel column chromatography. Up to three peaks of activity were seen in each chromatogram, representing free reduced technetium, the monocomplex, and the biscomplex of Tc-HIDA respectively. In all cases the free reduced technetium component diminished to reach a plateau at less than 4% of total activity, by 1 h. In both "brands" of diethyl HIDA there was a transformation from the monocomplex to the biscomplex which took about one hour. The rate of this transformation was increased by raising the temperature of incubation, or by agitation during incubation. In the para-butyl HIDA this transformation was again noted, but was incomplete. In the dimethyl HIDA the monocomplex form was not seen. There was no noticeable disintegration of any Tc-HIDA complex up to 6 h. It is suggested that HIDA should be incubated for 1 h after preparation, before use, to achieve a stable composition.

Investigation of Erythrina spp. VII. Chemical constituents of Erythrina variegata var. orientalis bark

The petroleum ether extractive of the bark of Erythrina variegata var. orientalis was fractionated and shown to be composed of wax alcohols and wax acids, alkyl ferulates, alkyl phenolates, stigmasterol, sitosterol, campesterol and possibly citrostadienol/24-methylenelophenol. The ethanol extractive yielded chloroform-soluble and water-soluble bases, identified as erysovine and stachydrine, respectively.