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PubMed2005

Influenza virus assembly and budding in raft-derived microdomains: a quantitative analysis of the surface distribution of HA, NA and M2 proteins.

Influenza virus hemagglutinin (HA) and neuraminidase (NA) are known to associate with lipid rafts, membrane microdomains comprised of densely packed cholesterol and sphingolipids. These specialized membrane regions are believed to be involved in the budding of many enveloped viruses including influenza virus. Quantitative analysis of HA distribution on the surface of virus-infected cells by immunogold staining shows an organization into clusters that grow in size as the expression level of HA increases with time post-infection (p.i.) ( approximately 325-500 nm at 4 h p.i. and approximately 425-600 nm at 6 h p.i.). These HA-containing clusters are likely derived from lipid rafts as they contain a high density of the raft marker ganglioside GM1 and are dependent upon the presence of cholesterol. The clustering of HA is an intrinsic property of the HA protein and occurs in the absence of expression of other viral proteins. NA is also found sequestered within the same microdomains as HA, whereas the M2 ion channel protein does not concentrate within the raft-like microdomains. Quantification of the distribution of surface expressed HA by examining serial sections of virus-infected cells suggests that the HA-containing microdomains give rise to regions of influenza assembly and budding.

Animals↗
PubMed2003

Relationship between stability of folding intermediates and amyloid formation for the yeast prion Ure2p: a quantitative analysis of the effects of pH and buffer system.

The dimeric yeast protein Ure2 shows prion-like behaviour in vivo and forms amyloid fibrils in vitro. A dimeric intermediate is populated transiently during refolding and is apparently stabilized at lower pH, conditions suggested to favour Ure2 fibril formation. Here we present a quantitative analysis of the effect of pH on the thermodynamic stability of Ure2 in Tris and phosphate buffers over a 100-fold protein concentration range. We find that equilibrium denaturation is best described by a three-state model via a dimeric intermediate, even under conditions where the transition appears two-state by multiple structural probes. The free energy for complete unfolding and dissociation of Ure2 is up to 50 kcal mol(-1). Of this, at least 20 kcal mol(-1) is contributed by inter-subunit interactions. Hence the native dimer and dimeric intermediate are significantly more stable than either of their monomeric counterparts. The previously observed kinetic unfolding intermediate is suggested to represent the dissociated native-like monomer. The native state is stabilized with respect to the dimeric intermediate at higher pH and in Tris buffer, without significantly affecting the dissociation equilibrium. The effects of pH, buffer, protein concentration and temperature on the kinetics of amyloid formation were quantified by monitoring thioflavin T fluorescence. The lag time decreases with increasing protein concentration and fibril formation shows pseudo-first order kinetics, consistent with a nucleated assembly mechanism. In Tris buffer the lag time is increased, suggesting that stabilization of the native state disfavours amyloid nucleation.

Amyloid↗
PubMed2005

Automated quantitative analysis (AQUA) of in situ protein expression, antibody concentration, and prognosis.

BACKGROUND: Disparate results in the immunohistochemistry literature regarding the relationship between biomarker expression and patient outcome decrease the credibility of tissue biomarker studies. We investigated whether some of these disparities result from subjective optimization of antibody concentration. METHODS: We used the automated quantitative analysis (AQUA) system and various concentrations of antibodies against HER2 (1 : 500 to 1 : 8000 dilutions), p53 (1 : 50 to 1 : 800 dilutions), and estrogen receptor (ER; 1 : 100 and 1 : 1000 dilutions) to assess expression of HER2 and p53 in a tissue microarray containing specimens from 250 breast cancer patients with long-term survival data available. HER2 expression in the tissue microarray was also assessed by conventional immunohistochemistry. Relative risk (RR) of disease-specific mortality was assessed for every cutpoint with the X-tile program. Cumulative disease-specific survival was assessed by the Kaplan-Meier method. All statistical tests were two-sided. RESULTS: For HER2 and p53 and an optimal cutpoint, when a high antibody concentration (i.e., 1 : 500 dilution) was used with the AQUA system, low expression was associated with poorer survival than high expression; however, when a low antibody concentration (i.e., 1 : 8000 dilution) was used, high expression was associated with poorer survival. For example, for a 1 : 8000 dilution of HER2 antibody and high expression defined as the top 15% of HER2 expression, high HER2 expression was associated with increased disease-specific mortality (RR = 1.98, 95% confidence interval [CI] = 1.21 to 3.23; P = .007), compared with low expression. However, for a 1 : 500 dilution of HER2 antibody and high expression defined as the top 85% of HER2 expression, high HER2 expression was associated with decreased disease-specific mortality (RR = 0.47, 95% CI = 0.29 to 0.76; P = .002), compared with low HER2 expression. CONCLUSIONS: Biomarker antibody concentration appears to dramatically affect the apparent relationship between biomarker expression and outcome.

Adult↗
PubMed2003

[Continual and quantitative analysis of cellular apoptosis by electron and fluorescence microscope].

OBJECTIVE: To evaluate the usage of fluorescent microscope in analyzing cellular apoptosis. METHODS: VP16 (the inhibitor of Top-II) and Azard Sodium(NaN3, the chemical toxic agent) were used to induce cellular apoptosis and necrosis respectively. The cellular changes were analyzed continually and quantitatively by transmission electromicroscope and fluorescent microscope stained by Hoechst 33258. RESULTS: Under the observation of fluorescent microscope and electromicroscope, HL60 cells showed pyknosis, chromatin aggregation and karyorrhexis (the features of apoptosis) in the induction of VP16; whereas the cells in the induction of NaN3 presented necrotic changes of karyolysis and chromatin diffusion. This indicated that there were different features in cellular apoptosis and necrosis under fluorescent microscope. In a time course observation of fluorescent microscope, the pyknosis began at 4 h after induction and peaked at 8 h, whereas karyorrheix reached 80% at 24 h, suggesting that the pyknosis preceded the karyorrheix. CONCLUSION: The fluorescent microscopic observation is a technique in continual and quantitative analysis of apoptosis, which may be used to distinguish the cellular apoptosis and necrosis.

Apoptosis↗
PubMed1992

Quantitative analysis of the tracking of blood pressure and relative factors in childhood: Shimane Heart Study.

1. In order to clarify the predictive factors of cardiovascular diseases caused by hypertension and hypercholesterolaemia in adults, a longitudinal epidemiological study was started in 1978. 2. This paper reports the results of research carried out from a quantitative analysis of the tracking of blood pressure and anthropometric parameters in children and adolescents using a tracking index. The index was calculated according to the changes in blood pressure quintiles for the whole population during the observation period. 3. The study population consisted of 5148 Japanese children living in the city of Izumo, who were examined every 3 years between the ages of 6 and 15 years old. 4. Although systolic blood pressure tracked weakly during childhood and adolescence, there was no significant relation between the tracking of systolic blood pressure and a family history of hypertension. 5. The tracking indices of the anthropometric parameters were better than those of systolic blood pressure, but the index of the left ventricular mass was similar to that of systolic blood pressure. 6. In conclusion the tracking of blood pressure might be determined by the tracking of bodyweight and height.

Adolescent↗
PubMed2006

[Quantitative analysis of psychometric indicators among 40-55 years old accelerant Georgian men and women of normal physical development].

Determination of individual characteristics of a human being causes much interest. Furthermore, you can seldom come across the studies about determination of psychological categories of accelerants. The aim of the present work was to determine quantitative analysis of psychometric indicators among 40-55 years old accelerant Georgian men and women of normal physical development for given age scales as well as to determine personal characteristics of each person to be researched. On the basis of conducted research we may shape out, that older Georgian women are characterized with phlegmatic temperament and introversive character. They are observed to have average degree of logic and verbal intellect; constitutional types of mid exciting, conflicting and static mood. While elder Georgian men have sanguine temperament, they are characterized with extroversive character, average degree of logic intellect, plastic-dynamic and constitutional-stable mood; they are considered to be harmonic and dynamic constitutional types. We have also established that Georgian accelerant men are observed to have phlegmatic temperament, extroversion, average mathematical intellect and conflicting and static mood. Accelerant Georgian women displayed phlegmatic temperament, extroversion, average logic intellect, and conflicting and static mood. But still they were observed, though seldom, to have harmonic and dynamic character.

Adult↗
PubMed2004

Quantitative analysis of simvastatin and its beta-hydroxy acid in human plasma using automated liquid-liquid extraction based on 96-well plate format and liquid chromatography-tandem mass spectrometry.

An assay based on automated liquid-liquid extraction (LLE) and liquid chromatography-tandem mass spectrometry (LC/MS/MS) has been developed and validated for the quantitative analysis of simvastatin (SV) and its beta-hydroxy acid (SVA) in human plasma. A Packard MultiProbe II workstation was used to convert human plasma samples collected following administration of simvastatin and quality control (QC) samples from individual tubes into 96-well plate format. The workstation was also used to prepare calibration standards and spike internal standards. A Tomtec Quadra 96-channel liquid handling workstation was used to perform LLE based on 96-well plates including adding solvents, separating organic from aqueous layer and reconstitution. SV and SVA were separated through a Kromasil C18 column (50 mm x 2 mm i.d., 5 microm) and detected by tandem mass spectrometry with a TurboIonspray interface. Stable isotope-labeled SV and SVA, 13CD(3)-SV and 13 CD(3)-SVA, were used as the internal standards for SV and SVA, respectively. The automated procedures reduced the overall analytical time (96 samples) to 1/3 of that of manual LLE. Most importantly, an analyst spent only a fraction of time on the 96-well LLE. A limit of quantitation of 50 pg/ml was achieved for both SV and SVA. The interconversion between SV and SVA during the 96-well LLE was found to be negligible. The assay showed very good reproducibility, with intra- and inter-assay precision (%R.S.D.) of less than 7.5%, and accuracy of 98.7-102.3% of nominal values for both analytes. By using this method, sample throughput should be enhanced at least three-fold compared to that of the manual procedure.

Chromatography, Liquid↗
PubMed2004

Quantitative determination of expression of the prostate cancer protein alpha-methylacyl-CoA racemase using automated quantitative analysis (AQUA): a novel paradigm for automated and continuous biomarker measurements.

Despite years of discovery and attempts at validation, few molecular biomarkers achieve acceptance in the clinical setting. Tissue-based markers evaluated by immunohistochemistry suffer from a high degree of inter- and intraobserver variability. One recent advance in this field that promises to automate this process is the development of AQUA, a molecular-based method of quantitative assessment of protein expression. This system integrates a set of algorithms that allows for the rapid, automated, continuous, and quantitative analysis of tissue samples, including the separation of tumor from stromal elements and the subcellular localization of signals. This study uses the AQUA system to assess a recently described prostate cancer biomarker, alpha-methylacyl-CoA-racemase (AMACR), and to determine the effectiveness of the quantitative measurement of this marker as a means for making the diagnosis of prostate cancer. Using a prostate cancer progression tissue microarray containing a wide range of prostate tissues, AQUA was directly compared to standard immunohistochemical evaluation for AMACR protein expression using the p504s monoclonal antibody. Both methods produced similar results showing AMACR protein expression to be strongest in the clinically localized prostate cancer, followed by the metastatic tumor samples. Benign prostate tissue was categorized as negative for most tissue samples by immunohistochemistry. However, AMACR was detectable using the AQUA system at low levels using the standard 1:25 dilution but also at 1:250 dilution, which is not detectable by light microscopy. The AQUA system was also able to discriminate foamy gland prostate cancers, which are known to have a lower AMACR expression than typical acinar prostate cancers, from benign prostate tissue samples. Finally, a receiver-operating-characteristic curve was plotted to determine the specificity of the AMACR AQUA Z-score (normalized AQUA score) to predict that a given tissue microarray sample contains cancer. The area under the curve was calculated at 0.90 (P < 0.00001; 95% CI, 0.84 to 0.95). At an AMACR AQUA Z-score score of -0.3, 91% of the 70 samples classified as prostate cancer were correctly categorized without the intervention of a pathologist reviewing the tissue microarray slide. In conclusion, the AQUA system provides a continuous measurement of AMACR on a wide range of prostate tissue samples. In the future, the AMACR AQUA Z-score may be useful in the automated screening and evaluation of prostate tissue biomarkers.

Biomarkers, Tumor↗
PubMed2005

Quantitative analysis of 23-hydroxybetulinic acid in mouse plasma using electrospray liquid chromatography/mass spectrometry.

23-Hydroxybetulinic acid is a newly isolated derivative of betulinic acid. The agent exhibits potential anti-tumor activity and functions in this regard via apoptosis. In support of pharmacokinetic and toxicological evaluations, a new assay based on liquid chromatography/mass spectrometry (LC/MS) was developed for the quantitative analysis of 23-hydroxybetulinic acid. Sample preparation consisted of extraction of the plasma by the addition of methylene chloride followed by centrifugation. Aliquots of the supernatant were analyzed using an isocratic reversed-phase high-performance liquid chromatography (HPLC) system coupled to a negative ion electrospray mass spectrometer. Molecules of 23-hydroxybetulinic acid and the internal standard limonin were detected using selected ion monitoring at m/z 471 and 469, respectively. The limit of detection of 23-hydroxybetulinic acid was 0.05 pg (0.11 fmol) injected on-column (10 pg/mL, 5 microL injection volume), and the limit of quantitation was 10 pg (21.19 fmol, 2 ng/mL, 5 muL injection volume). 23-Hydroxybetulinic acid was stable in plasma samples at -20 degrees C for at least 3 weeks. The intra-day and inter-day coefficients of variation of the assay were 3.0 and 4.8%, respectively. The utility of the assay was demonstrated by measuring 23-hydroxybetulinicacid in mouse plasma following intragastric administration (IG) in vivo. Pharmacokinetic parameters were calculated using the 3P97 pharmacokinetic software package. A two-compartment, first-order model was selected for pharmacokinetic modeling. The result showed that after IG of 200 mg/kg 23-hydroxybetulinic acid, the plasma concentrations reached peaks at 2 h with C(max) of 3.1 microg/mL. The 200 mg/kg 23-hydroxybetulinic acid suspension IG doses were found to have long elimination half-lives of 25.6 h and low bioavailability of 2.3%. No interference was noted due to endogenous substances. These analytical methods should be of value in future studies related to the development and characterization of 23-hydroxybetulinic acid.

Animals↗
PubMed1999

Quantitative analysis of the composition of the native and scrambled ribonuclease A.

Reversible conversion between the native and scrambled proteins can be applied to analyze the denaturation curve of a disulfide-containing protein. In the case of RNase A, scrambled species could not be well separated from the native species by HPLC to permit precise quantitative analysis of the extent of denaturation. Methods are developed here to overcome this problem. The methods exploit the difference of conformational stability between the native and scrambled RNase A. When a sample of partially denatured RNase A was placed under mild reducing conditions (0.2-1 mM dithiothreitol for 10 min), the disulfide bonds of the native RNase A remain intact, whereas those of scrambled isomers become fully reduced. The native and fully reduced species of RNase A can be completely separated by HPLC. Alternatively, a mixture of partially denatured RNase A can be treated with mild concentration of proteolytic enzymes (trypsin or thermolysin). In this approach, scrambled isomers of RNase A were totally fragmented and readily separated from the native RNase A. These methods allow analysis and construction of the denaturation curves of RNase A in the presence of urea, GdmCl and GdmSCN.

Animals↗
PubMed2006

The relationship between nasopharyngeal carcinoma tumor volume and TNM T-classification: a quantitative analysis.

Recent findings show that tumor volume is a significant prognostic factor for the treatment of nasopharyngeal carcinoma (NPC). The inclusion of tumor volume as an additional prognostic factor in the UICC TNM classification system was suggested; however, how tumor volume could possibly be incorporated is still unexplored. In this paper, we report a quantitative analysis on the relationship between NPC tumor volume and T-classification, using the data from 206 NPC patients. By T-classification and semi-automatic tumor volume measurement, the difference in tumor volumes among the various TNM T-classification groups was examined. In addition, a statistics-based analysis scheme, which used the T-classification as the "gold standard", was proposed to classify NPC tumors into volume-based groups to explore the possible links. The results show that NPC tumor volume has positive correlation with advancing T-classification groups and significant difference existed in the distribution of T-classification among various volume-based groups (P < 0.001). By the proposed statistical scheme, tumor volume could be included as an additional prognostic factor in the TNM framework, following validation studies.

Adolescent↗
PubMed1993

Qualitative and quantitative analysis of the progressive cerebral damage after middle cerebral artery occlusion in mice.

The middle cerebral artery occlusion (MCAO) in mice induces a focal cerebral ischaemia at the level of the tempo-parietal cortex. Histological staining and immunohistochemical markers were used to characterize the temporal progression of the cerebral infarct: both qualitative and quantitative analyses were performed at different days after the MCAO. At 3 days after MCAO, an extensive necrosis of the cerebral parenchyma was accompanied by extravasation and by massive oedema. After 7 days, GFAP marker showed a gliotic reaction with alteration of the astrocytes membrane permeability (S100 marker). Positivity for acid phosphatase staining indicated the presence of macrophages. At Day 14 and 21 following MCAO, the histological profile was essentially similar. Interestingly, at Day 7, 14 and 21, a previously unreported gliosis was observed in the subthalamic area. Quantitative analysis showed a significantly large infarct volume at Day 3 (7.88 +/- 1.95 mm3 +/- S.E.M.) compared to Day 7 (4.28 +/- 0.47 mm3 +/- S.E.M.). At Day 14 and Day 21 the infarct volumes were further decreased to 2.00 +/- 0.52 and 1.43 +/- 0.39 mm3 +/- S.E.M., respectively. These results suggest that it is important to consider the time of evaluation of cerebral ischaemia-induced cerebral infarct, especially in studies which aim to evaluate the neuroprotective effect of putative therapeutic agents.

Animals↗
PubMed2006

Quantitative analysis along the pyramidal tract by length-normalized parameterization based on diffusion tensor tractography: application to patients with relapsing neuromyelitis optica.

In this study, we introduced a length-normalized parameterization method to establish anatomical correspondence of white matter fiber tracts across subjects and applied this method to investigate the presence of abnormal diffusion along the pyramidal tract (PYT) of relapsing neuromyelitis optica (RNMO) patients without visible brain lesions. In this approach, the part of the PYT between the lowest slice of the cerebral peduncle and the uppermost slice of the lateral ventricle was reconstructed to establish the anatomical correspondence across subjects using diffusion tensor tractography. Then it was parameterized by normalizing its length and dividing equally the normalized length into a certain number of segments, so that the comparability of each segment across subjects along the PYT was established. Tract-specific diffusion indices, including directionally averaged diffusivity (D(av)), fractional anisotropy (FA), primary diffusivity (lambda(1)) and transverse diffusivity (lambda(23)), were obtained from each segment. Thus, the distribution maps of these indices along the PYT were obtained. The distribution maps of D(av), FA, and lambda(23) of RNMO patients were significantly different from those of healthy controls, especially in the lower part of the PYT. The differences may be caused by secondary degeneration to lesions in the spinal cord. In conclusion, a length-normalized parameterization method is proposed to establish anatomical correspondence for the PYT. Compared with existed methods, a major merit of our method is to provide comparability across subjects along the PYT on the basis of diffusion tensor tractography and to make it possible for the quantitative analysis along the fiber tract. This method can also be used to quantitatively analyze other white matter fiber tracts between two definite anatomic landmarks in many neurological or psychiatric diseases.

Adult↗
PubMed1984

Electroretinographic responses and retrograde changes of retinal morphology after intracranial optic nerve section. A quantitative analysis in the cat.

Previous experiments have shown that the ERG response to alternating gratings vanishes gradually within 4 months after transection of the optic nerve, changes begin after 2-3 weeks. The response to gratings of low spatial frequencies deteriorates earlier than the response to gratings of high spatial frequencies (Maffei and Fiorentini 1981). Quantitative analysis of ganglion cell sizes in retinal wholemounts shows that ganglion cell shrinkage and ganglion cell loss begin at three weeks in the periphery of the retina, particularly in the temporal retina. The same morphological alteration subsequently becomes apparent also in the area centralis and the nasal retina, respectively. The main and early cell loss occurs among medium sized ganglion cells, supposedly the beta-cells. Among the alpha-cells only shrinkage is observed up to two months postoperatively. Light- and electron microscopic examination of cross sections through the retina show that pathological changes are restricted to the innermost layers.

Animals↗
PubMed1997

Quantitative analysis of the usage of human T cell receptor alpha and beta chain variable regions by reverse dot blot hybridization.

We previously developed an adaptor ligation-mediated PCR method to amplify the T cell receptor (TCR) cDNA pools. In the present study we applied reverse dot blot hybridization to PCR-amplified specimens for quantitative analysis of the usage of TCR alpha and beta chain variable (V) region. 44 VA sequence-specific oligonucleotide probes (SSOPs) and 38 VB SSOPs were synthesized corresponding to unique sequences of VA and VB subfamilies. Peripheral blood lymphocytes of ten healthy donors and five T cell clones established from bone marrow cells were examined for VA and VB usage using this method. The results were consistent with those obtained by a colony hybridization method and those by immunofluorescence staining using monoclonal antibodies to VA and VB. Thus, reverse dot blot hybridization for TCR V(alpha) and Vbeta is a new, easy and dependable technique useful for analysis of VA and VB usage by human T cells.

Base Sequence↗
PubMed2003

Differential features of metabolic abnormalities between medial and lateral temporal lobe epilepsy: quantitative analysis of (18)F-FDG PET using SPM.

UNLABELLED: Because limited resection could yield an equally good surgical outcome as standard anterior resection in temporal lobe epilepsy (TLE), the differentiation of medial from lateral TLE is important. We tried to find the differential features in metabolic abnormalities between medial and lateral TLE groups using quantitative analysis including statistical parametric mapping (SPM). METHODS: We examined 113 (18)F-FDG PET scans of TLE patients who had surgically and pathologically proven lesions and a good surgical outcome (78 medial TLE, 35 lateral TLE). Each scan was compared with those of 22 healthy control subjects to detect hypometabolic regions using a t test of the SPM method and interhemispheric asymmetry using 2-group, 2-condition analysis on SPM. Group analysis was performed between medial and lateral TLE using mirrored PET images. The sensitivity was defined as the detection rate of hypometabolism in the ipsilateral temporal lobes, and the specificity was defined as the nondetection rate in the contralateral lobes. The extent of the hypometabolism was calculated as the number of significant voxels, and the severity was calculated by the asymmetry index (ASI), in the medial or lateral temporal lobes on Statistical Probabilistic Anatomical Map template images. RESULTS: The hypometabolism in the temporal lobes was detected ipsilateral to the seizure focus in 76% of the TLE patients (76% in medial TLE, 77% in lateral TLE) but on the contralateral temporal lobes in 32% of the patients. After considering interhemispheric temporal asymmetry, the sensitivity was found to be 89%, and the specificity was 91% without differences between the medial and lateral TLE groups. In both medial and the lateral TLE, the hypometabolism was more prominent in the lateral cortical structures than in the medial structures. The hypometabolism in the medial temporal structures was found less frequently in the lateral TLE group, and the extent of the hypometabolism was significantly larger in the medial TLE group. ASIs of the medial temporal structure and superior temporal gyrus of lateral temporal structure were significantly higher in the medial TLE. CONCLUSION: SPM analysis of (18)F-FDG PET in TLE patients could localize accurately the seizure focus and helped in the discrimination of the medial TLE from the lateral TLE. We suggest the lateral TLE, rather than the medial TLE, should be considered when glucose metabolism is relatively preserved in the medial temporal structures.

Adult↗
PubMed1994

Chromatographic methods for quantitative analysis of native, denatured, and aggregated basic fibroblast growth factor in solution formulations.

High-performance liquid chromatography (HPLC) methods were developed for evaluating stability of human recombinant basic fibroblast growth factor (bFGF) against denaturation and aggregation in solution formulations. Reversed-phase chromatography (RP-HPLC)-insensitive to bFGF tertiary structure--was used to measure total soluble protein; heparin affinity chromatography (HepTSK) provided quantitative analysis of native bFGF species. The folding state of bFGF was determined by fluorescence spectroscopy: Tryptophan emission, which was quenched in native protein, increased upon unfolding. Slow unfolding/refolding kinetics of bFGF in 2 M guanidine hydrochloride made possible the separation of native from denatured species by size exclusion chromatography (SEC). Although the tertiary structure affected bFGF retention times, it did not change the sample recovery by SEC. These chromatographic techniques, which quantitatively measure physical and chemical changes taking place in solution formulations, can be used in future investigations of bFGF stability.

Chemical Phenomena↗
PubMed2001

Qualitative and quantitative analysis of proteins and peptides in milk products by capillary electrophoresis.

Milk protein is an important component of the human diet throughout much of the world. The ability to assess the relative composition and integrity of milk proteins or peptides in dairy foods or food ingredients is important because these molecules have a profound effect on product functionality and quality. This communication describes two capillary electrophoretic methods that are useful for the analysis of proteins and casein-derived peptides in cheese and milk products. One technique, which uses a buffer containing citrate/phosphate (pH 3.3), 4 M urea, and a polymeric additive in a coated capillary, is useful for qualitative and quantitative analysis of proteins and peptides in milk, cheese, and whey products. The second method employs a citrate/phosphate buffer (pH 2.8) and a bare silica capillary, and is well suited for the analysis of small, casein-derived peptides in aqueous cheese extracts.

Animals↗