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Biomedical subjects

R M Caprioli

Publications and source records attributed to R M Caprioli.

At least 55 records · Page 3Linked to original sources
PubMed1988

Microbore high-performance liquid chromatography-mass spectrometry for the analysis of proteolytic digests by continuous-flow fast-atom bombardment mass spectrometry.

Microbore high-performance liquid chromatographic (HPLC) techniques have been combined with fast atom bombardment mass spectrometry (FAB-MS) for the mass-specific detection of mixtures of peptides produced by proteolytic hydrolysis of proteins. The continuous-flow FAB interface has been utilized for direct coupling of the microbore HPLC system and the mass spectrometer. Conditions are reported for the effective separation of 100 pmol of peptides at flow-rates of 5 microliters/min with acetonitrile gradients and 1-mm I.D. C8 columns. A comparison is also made between columns of 5 and 25 cm lengths for the separation of peptide mixtures. Data are presented for the separation of peptides on a slurry-packed C18 fused-silica capillary column with the continuous-flow HPLC-FAB-MS interface at flow-rates of 3 microliters/min.

Chromatography, High Pressure Liquid↗
PubMed1988

On-line fast atom bombardment analysis of dynamic biological systems.

The continuous-flow fast atom bombardment probe interface has been used for the direct analysis of aqueous biochemical reactions. This device was used in two ways: in a constant flow mode and a flow injection mode. Each method has particular advantages which are illustrated with specific applications, including measurement of enzyme kinetics, comparative rates of hydrolysis of multi-substrate/single enzyme reactions, C-terminal peptide sequence analysis, and characterization of multi-enzyme/single substrate systems.

Chromatography, High Pressure Liquid↗
PubMed1988

Dose-related differential accumulation of morphine in specific regions of rat brain determined by mass fragmentography.

Regional morphine accumulation was examined in 8 brain areas (cerebral cortex, hippocampus, striatum, midbrain, hypothalamus, thalamus, medulla oblongata and cerebellum) following either a single dose or incremental doses administered by intraperitoneal injection. Morphine levels were determined by gas chromatography-mass spectrometry with chemical ionization detection. Prior to morphine assay, the vasculature was cleared of blood by saline perfusion to eliminate distortion of tissue-morphine by blood-morphine. Results indicate a dose-dependent, differential accumulation of morphine in different brain regions following incremental morphine administration. Three distinct uptake profiles were obtained, with the cerebellum, hippocampus, medulla and cortex showing roughly linear accumulation the midbrain, striatum and thalamus showing nonlinear accumulation, and the hypothalamus showing significantly higher absolute morphine levels than any other brain region.

Animals↗
PubMed1987

Microbore HPLC/mass spectrometry for the analysis of peptide mixtures using a continuous flow interface.

Microbore HPLC techniques have been combined with fast atom bombardment mass spectrometry to provide HPLC/MS capabilities for the analysis of mixtures of peptides and small proteins. The interface between the liquid chromatograph and mass spectrometer is a continuous flow direct insertion probe which contains a fused silica capillary that delivers the eluting solvent to the FAB source of the mass spectrometer at a rate of 5-10 microL/min. Data are presented for the analysis of several mixtures of peptides ranging in molecular weights from about 900 to 6000 daltons. In addition, the analysis of 100 pmol of a tryptic digest of whale myoglobin is shown where 16 of the possible 19 peptides were identified in the mass range m/z 2200-250. The advantages of this approach to HPLC/MS are a relatively high sensitivity because of the low flow rates and low background, and the ability to detect high molecular weight compounds.

Animals↗
PubMed1987

The regulation of glycan processing in glycoproteins. The effect of avidin on individual steps in the processing of biotinylated glycan derivatives.

The effect of the protein matrix on glycan processing by rat liver Golgi enzymes has been evaluated by a direct comparison of substrate----products conversion of a free glycan and of the same glycan linked to a protein. The glycan substrates had the general structure R-glycan where R represented either biotinyl-Asn-GlcNAc2- or 6-(biotinamido)hexanoyl-Asn-Glc-NAc2- and the protein used was avidin; the extension arm in one of the glycan substrates permitted the additional comparison of two avidin-biotin-glycan complexes. By the use of different glycans as substrates, by the presence or absence of donor substrates (UDP-GlcNAc, UDP-Gal, and CMP-sialic acid (Sia) and/or the inhibitor, swainsonine, it was possible to dissect the individual steps involved in the conversion of R-Man6 (or R-Man5) to a biantennary complex glycan, R-Man3-GlcNAc2-Gal2-Sia2 or to the hybrid glycan R-Man5-GlcNAc-Gal-Sia. Using fast atom bombardment-mass spectrometry to identify and quantify the substrates and products of each parallel incubation of free and avidin-bound substrates, the following observations were made. With the substrate without the extension arm, avidin-binding inhibited mannosidase I, GlcNAc transferase I, and the second step of the reaction catalyzed by mannosidase II (R-Man4-GlcNAc----R-Man3-GlcNAc); the second step of the reaction catalyzed by Gal-transferase was also inhibited to a lesser extent. This inhibition was greatly reduced or absent with the substrates with the extension arm and was consequently referred to as the short range effect. A long range effect of avidin binding expressed by both substrates with and without extension arm was observed for Gal-transferase acting in the hybrid glycan pathway (R-Man5-GlcNAc----R-Man5-GlcNAc-Gal) in the presence of swainsonine and also for Sia-transferase in the catalysis of the incorporation of the second Sia residue into the complex product (R-Man3-GlcNA2-Gal2-Sia----R-Man3-GlcNAc2- Gal2-Sia2) and to a lesser extent in the hybrid pathway (R-Man5-GlcNAc-Gal----R-Man5-GlcNAc-Gal-Sia). GlcNAc transferase II did not appear to be affected by avidin. Based on the information available on the biotin-binding site in avidin, it is proposed that the short range effect reflects the masking of the core chitobiose unit in the avidin-glycan complexes in the absence of the extension arm, but not in the presence of the arm, and that the early processing enzymes thus may require a fully exposed chitobiose for full activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Alkaloids↗
PubMed1986

High sensitivity mass spectrometric determination of peptides: direct analysis of aqueous solutions.

The high sensitivity analysis of peptides by fast atom bombardment mass spectrometry has been achieved using a continuous flow probe for the introduction of samples contained in aqueous solutions. Small aliquots of sample (0.5-1 microliter) are injected into a solvent flow containing water/glycerol (8:2). For several peptide samples tested whose molecular weights were between 1000 and 1500 daltons, molecular ions were selectively monitored at the 20 fmol level with a signal-to-chemical noise of about 4:1, and full scan data were obtained on about 5 pmol of sample. The increase in sensitivity observed using the continuous flow probe is shown to be a consequence of both the decrease in the chemical background noise and to the increase in ion yields obtained from the bombardment of aqueous sample solutions.

Mass Spectrometry↗
PubMed1986

Peptide sequence analysis using exopeptidases with molecular analysis of the truncated polypeptides by mass spectrometry.

Fast atom bombardment mass spectrometry is used for the analysis of the series of molecular products formed by the cleavage of polypeptide substrates with the exopeptidases carboxypeptidase Y and leucine aminopeptidase. By following the polypeptide molecular species rather than the released residues, sequence information is obtained regardless of the relative rates of cleavage of peptide bonds. In addition, unambiguous assignments of sequence can be made in the presence of multiple identical residues. The lower level of sensitivity for the analysis is in the picomole range. When carboxypeptidase Y is used, the method provides a specific and sensitive method for the sequencing of polypeptides from the C-terminus.

Amino Acid Sequence↗
PubMed1986

Relationship of human milk pH during course of lactation to concentrations of citrate and fatty acids.

Human milk pH was measured in 309 samples obtained from 52 women who had delivered at term and lactated for as long as 10 months thereafter. The mean pH decreased from 7.45 for colostrum to a nadir of 7.04 during the second week of lactation. Thereafter, the pH of milk remained between 7.0 and 7.1 until 3 months postpartum and then increased gradually to 7.4 by 10 months. The change in hydrogen ion concentration in milk was associated with corresponding changes throughout lactation in the concentration of citrate but not with the concentration of lactose. Lactose concentration increased gradually for 3 weeks; the concentration of saturated medium-chain fatty acids increased more rapidly. One interpretation of these findings is that the hydrogen ions and citrate generated by mammary secretory cell metabolism are used after the second week of lactation for de novo synthesis of fatty acids more rapidly than they are synthesized. Milk samples from ruminants were found to have concentrations of hydrogen ions and citrate that are greater than and pH that is less than the respective measurements in human milk. The significance for the recipient infant of the predictable changes in human milk pH during lactation and of the higher pH of human milk throughout lactation relative to bovine milk is unknown. However, drug excretion into milk, milk enzyme activity, milk leukocyte function, and neonatal gastrointestinal function are affected by ambient pH and may be influenced by the pH of milk.

Animals↗
PubMed1985

Verification of the DNA predicted amino acid sequence of bacteriophage P22 tail protein by mass spectrometry.

Mass spectrometry was used to verify portions of a proposed amino acid sequence of the bacteriophage P22 tail protein which had been inferred from the DNA base sequence. The exopeptidases dipeptidyl aminopeptidase I and IV and dipeptidyl carboxypeptidase were used to hydrolyse intact protein and fragments generated by cyanogen bromide treatment of the tail protein. After partial purification by high performance liquid chromatography, peptides were identified by gas chromatography/mass spectrometry and fast atom bombardment mass spectrometry. The results indicate that the initiation amino acid, N-formylmethionine, has been removed from the N-terminal of the protein and that the protein ends at the termination codon which is 667 amino acids from the N-terminal residue. Nine regions of the protein from 13 to 42 residues in length were verified. All of the sequences checked were in the same DNA reading frame and corresponded to the proposed sequence.

Amino Acid Sequence↗
PubMed1983

Protein N-terminal analysis using fast atom bombardment mass spectrometry.

Fast atom bombardment (FAB) mass spectrometry was employed to identify and quantitate dansyl amino acids obtained in the N-terminal analysis of proteins. FAB mass spectra of dansyl amino acids are characterized by intense quasimolecular ions formed by cationization of the molecular species and fragment ions produced by cleavage of the bonds on either side of the sulfanyl group. Investigation of the dansyl amino acid responses using dansyl aminobutyric acid as an internal standard showed that dansyl amino acids can be determined quantitatively at a level of 0.1 nmol. N-terminal residue analysis was performed on a number of proteins to substantiate the technique including bovine serum albumin, pepsinogen, trypsinogen, bromelain, ribonuclease A, and bacteriophage P-22 tail protein.

Amino Acids↗
PubMed1983

Energy-dispersive X-ray fluorescence determination of platinum in plasma, urine, and cerebrospinal fluid of patients administered cis-dichlorodiammineplatinum(II).

A method involving the use of an energy-dispersive X-ray fluorescence spectrometer was developed for assaying total platinum concentrations in body fluids of patients treated with the antitumor drug cis-dichlorodiammineplatinum(II). Sample preparation by this procedure is simple, consisting in adding an internal standard (Zr) to 1 ml of biological fluid or tissue homogenate, pipetting 20 microliter of the sample onto a Mylar sample holder, and drying. This produces a thin-film sample, which effectively eliminates absorption enhancement effects due to other elements in the specimen. Standard addition studies were found to be linear in the concentration range of interest (0.1-10.0 micrograms/ml), with correlation coefficients exceeding 0.99. Minimum detection limits range from 0.10 to 0.25 micrograms Pt per ml, depending on the body fluid, which is adequate for routine patient monitoring after normal chemotherapeutic doses of cis-dichlorodiammineplatinum(II). In preliminary studies with mammalian liver, standard addition experiments were found to be linear and the minimum detection limit was found to be 1.4 micrograms/g dry weight.

Body Fluids↗
PubMed1983

Synthesis and spectroscopic analysis of modified bile salts.

For the study of hepatic bile acid transport in vivo, a series of modified bile salts were synthesized. The N-cholyl derivatives of L-leucine, L-alanine, D-alanine, beta-alanine, L-proline, and gamma-amino-butyric acid were prepared from cholic acid, ethyl chloroformate and the corresponding amino acid. Structural analysis of products was carried out mainly by electron impact mass spectrometry (20 eV) of the methyl ester/acetate derivatives. In all EI spectra, fragments in the lower mass region included McLafferty rearrangement ions (beta-cleavage) and product ions of gamma-cleavage in the vicinity of the amide linkage. In the upper mass region, fragmentation was characterized by consecutive eliminations of ketene and/or acetic acid from low intensity molecular ions. The purity of the products and their molecular weights were checked by a novel ionization technique in mass spectrometry, fast atom bombardment (FAB) mass spectrometry. FAB spectra were obtained from underivatized bile salts. The spectra were characterized by ions formed by attachment of a proton or an alkali ion to the bile salt to give intense M+H, M+Na, or M+K ions, which then showed little fragmentation.

Amino Acids↗
PubMed1983

Inhibition of human polymorphonuclear leukocyte function by components of human colostrum and mature milk.

To compare the effect of human colostrum (days 1 to 3 postpartum) and mature milk (days 170 +/- 24 postpartum) on the function of polymorphonuclear leukocytes (PMNL), Ficoll-Hypaque-separated PMNL from the blood of 60 healthy volunteers were incubated with whole colostrum, colostral lipid, and colostral aqueous phase from 30 mothers, or with mature whole milk and its separated components from 30 mothers, and tested for resting and zymosan-stimulated oxidative metabolism, functional activity, and the presence of Fc receptors. Stimulated oxygen consumption, quantitative nitroblue tetrazolium dye reduction, [1-(14)C]glucose utilization, and Fc receptors were significantly (P < 0.05 to P < 0.001) less in PMNL exposed to whole human colostrum or colostral lipid than in non-lipid-exposed cells or cells exposed to the aqueous phase of colostrum. In contrast, PMNL exposed to whole mature milk or to its lipid or aqueous phase caused no significant decrease in any of these parameters when compared to nonexposed cells. In assays of phagocytosis, colostral PMNL or blood PMNL exposed to colostral lipid had a significant (P < 0.001) decrease in their ability to ingest [methyl-(3)H]thymidine-labeled Staphylococcus aureus when compared to non-lipid-exposed PMNL. Blood PMNL exposed to lipid from mature milk had no decrease in ability to ingest S. aureus. Analysis of total lipid and total and individual fatty acid content revealed a uniform increase in all components in mature milk when compared to colostrum. Lipid or lipid-soluble material present in human colostrum but not mature milk causes inhibition of phagocytosis and respiratory burst-related activities of PMNL.

Blood Bactericidal Activity↗
PubMed1983

Clinical pharmacology of intraarterial cis-diamminedichloroplatinum(II).

After intraarterial (30 patients) or i.v. (seven patients) administration of cis-diamminedichloroplatinum, X-ray fluorescence spectrometry was used to measure platinum concentrations in plasma and urine. Arteries infused included hepatic (seven patients), carotid (six patients), iliac (ten patients), brachial (three patients), and femoral (four patients). All patients received i.v. mannitol. Pharmacokinetic parameters after intraarterial administration were similar to those after i.v. administration, although differences existed for different intraarterial routes of administration. Mean for all patients combined were: Co, 2.67 +/- 0.97 (S.D.) microgram/ml; t1/2 beta, 71.1 +/- 26.6 hr; clearance, 0.72 +/- 0.25 liters/hr/sq m; total volume of distribution, 45.2 +/- 17.0 liters/sq m; C x t, 167 +/- 72 mg/hr/liter; and 24-hr urinary excretion, 20 +/- 10% of the administered dose. Intrahepatic infusion of the drug was associated with a significantly lower Co (1.88 +/- 0.50 g/ml) and C x t (140 +/- 25 mg hr/liter) and significantly higher clearance (0.91 +/- 0.24 liters/hr/sq m) and volume of distribution (67.6 +/- 4.6 liters/sq m) than administration by other routes, suggesting first pass extraction of drug by liver. In addition, an apparent minor late rise in serum platinum concentration may suggest enterohepatic recirculation of drug. High fluid intake was associated with a low Co and a high volume of distribution, consistent with expansion of the central compartment by fluids. Low serum albumin (less than 3.5 g/dl) was associated with significant shortening of the t1/2 beta (50.5 +/- 21.6 hr), suggesting that the amount of unbound filterable drug may possibly be higher in patients with low serum albumin concentrations. Plasma from veins draining an infused area has a higher Co and C x t during infusion than concurrent plasma from peripheral veins. Thus, intraarterial administration of cis-diamminedichloroplatinum results in increased drug exposure of tumor in the infused area without substantially decreasing exposure of systemic tumor.

Cisplatin↗
PubMed1983

X-ray fluorescence spectrometry in the analysis of trace elements in human milk.

XRF has broad applications in the quantitative analysis of trace elements in biological materials. Evaluation of its potential for the analysis of trace elements in human milk was performed. Precision of the method was demonstrated by the low (less than 3%) coefficient of variation in reproducibility of analyses performed within a given day, on different days, and by different operators. Standard curves were constructed for human milk and correlation was high (r greater than 0.98) for each of nine metals analyzed. The lower limits of determination and minimum detection limits were calculated for nine elements. Excellent correlation (r greater than 0.99) was achieved in comparison of XRF TO AA in analysis of zinc in human milk. Preliminary results of the analysis of milk zinc, copper, and iron throughout the initial 8 months of lactation disclose a decrease in trace metal concentration, most notable for zinc, during the first 60 days.

Copper↗
PubMed1982

Fast atom bombardment mass spectrometry of estrogen glucuronides and sulfates.

Fast atom bombardment (FAB) mass spectra of 13 intact, underivatized glucuronides and/or sulfate salts are reported. Spectra are characterized by abundant ions formed by attachment of a proton, [M+H]+, or of an alkali ion, [M+alkali]+, to the glucuronide or sulfate salt. Fragment ions were of low intensity. FAB spectra can be used to obtain the molecular weight of a sample, to assess its purity and to identify the nature of the alkali of the glucuronide or sulfate salt.

Estradiol↗