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At least 19 recordsLinked to original sources

PubMed1978

Correlation of albumin production rates and albumin mRNA levels in livers of normal, diabetic, and insulin-treated diabetic rats.

We have studied the effects of alloxan-induced diabetes and subsequent insulin replacement on albumin and total hepatic protein synthesis. Diabetes resulted in a reduction to approximately 20% of normal in albumin synthesis relative to the rate of total protein synthesis in vivo and a reduction to 10% in the absolute rate of albumin secretion by perfused livers. In contrast, the synthesis of total secretory protein and retained hepatic protein was affected to a lesser extent by diabetes. Treatment of diabetic rats with insulin restored rates of albumin and total hepatic protein synthesis to normal levels. The molecular basis of these alterations in albumin synthesis was investigated by examining albumin mRNA levels in livers of normal, diabetic, and insulin-treated diabetic animals. The level of albumin mRNA, whether assayed by cell-free translation or by hybridization to a specific complementary DNA probe, was markedly decreased in livers of diabetic animals and was restored to normal by insulin treatment. These changes occurred in parallel with changes in the rates of albumin secretion observed in perfused liver, suggesting that albumin mRNA content is the primary factor responsible for altering rates of albumin synthesis under these conditions.

Albumins↗

PubMed1979

Immunochemistry of serum albumin. VI. A dynamic approach to the immunochemical cross reactions of proteins using serum albumins from various species as models.

Antisera against bovine serum albumin were raised in two rabbits. Serial bleedings were obtained at different times after the first immunization, and antisera from these serial bleedings were not mixed but were kept and studied separately. The immunochemical cross-reactions of these antisera with serum albumins from bovine, goat, sheep, porcine, horse, human and chicken were determined by immunoadsorbent studies. These were done by titration so that the values of maximum (plateau) binding by each albumin of radioiodinated antibodies were determined. In each rabbit, the immunochemical cross-reactivity was not static but increased progressievly with time after the first immunization. In the interval 7 days to 398 days the increases in cross-reaction were extremely large. pH dissociation studies revealed that, together with the increase in cross-reactivity of a given albumin with time after immunization, there was a restriction in the antibody heterogeneity towards populations possessing higher affinity. These results provide a rational explanation for the different values of cross-reactivities for a given albumin from different laboratories. The findings are analyzed in relation to the antigenic structure of albumin and their significance in evolutionary studies discussed.

Animals↗

PubMed1975

Brdicka currents observed with bovine serum albumin and completely reduced bovine serum albumin in the presence of urea.

In ammonia buffers of varying composition and pH, native bovine serum albumin and completely reduced bovine serum albumin, denoted by p(SH)35, yield quite different Brdicka current-voltage (i-E) curves, but they are identical in the presence of 5 mM calcium chloride. This means that in the presence of calcium, bovine serum albumin becomes completely reduced to p(SH)35. In 8 M urea and ammonia buffers the Brdicka i-E patterns of serum albumin and p(SH)35 are identical even in the absence of calcium, the effect of calcium on the first wave being negligible while calcium slightly increases the second wave. The maximum polarographic effect is attained at urea concentrations of about 5-6 M. Quite generally, the appearance of a second Brdicka wave is attributed to complexation of Co(II) with S- and a group of ligands that is different on the second than on the first wave. The effect of calcium on Brdicka currents of bovine serum albumin in the absence of urea is attributed to an orientation of the protein on the surface of the electrode such that all disulfide groups are reduced and with other ligands can complex with Co(ii). Denaturation of bovine serum albumin in buffers with a pH less than 10.5, and which are 8 M in area, is (polarographically) completely reversible if dilution is made within 15 minutes after preparation. Changes in Brdlcka I-E patterns upon longer aging at varying pH are attributed-in part at least-to dimerization of the denatured protein by interaction of pS- in one molecule with -S-S-in another.

Ammonia↗

PubMed1979

Evaluation of 99mTc-albumin dilution curve with simultaneous injection of 99mTc- and 131I-albumins.

A critical comparison of radiocardiograms with 99mTc- and 131I-albumins was made to determine whether or not 99mTc-albumin can be used as a tracer for measuring blood volume (BV) and cardiac output (CO). Simultaneous injection of both isotopes was given to twenty-two patients to obtain radiocardiograms for each by means of a single scintillation counter with two pulse height analyzers. Such method allows for the determination of the energy levels for both 99mTc and 131I. The radiocardiographic pattern was somewhat different between 99mTc- and 131I-radiocardiograms: The ratio of left to right peak height was 16% on the average lower in the 99mTc-radiocardiogram in the 131I-one. The reason for the lower ratio is explained by greater absorption of 99mTc-radioactivity within the soft tissue interposing between the scintillation probe and heart. The values for 99mtc-derived blood volume were 7.4% on the average larger than those for 131I-derived blood volume (p less than 0.01), although the correlation was excellent (r = 0.98, p less than 0.01). There was no systemic difference between cardiac output determined by 99mTc- and 131I-albumins since the overstimation of blood volume can compensate for the understimation of CO/BV by 99mTc-study. In view of its rapid extravasation, 99mTc-albumin is not so appropriate tracer for accurate measurements of BV and CO/BV, although it may be used for measurement of cardiac output.

Adolescent↗

PubMed1978

The modification of the lone tryptophan residue in human serum albumin by 2-hydroxy-5-nitrobenzyl bromide. Characterization of the modified protein and the binding of L-tryptophan and benzodiazepines to the tryptophan-modified albumin.

The possible function of the lone tryptophan residue of human serum albumin in the stereospecific binding site for indole and benzodiazepine compounds was investigated by chemical modification. This residue can be selectively modified with 2-hydroxy-5-nitrobenzyl bromide. The modification alters the conformation of the albumin only slightly, as revealed by circular dichroism, fluorescence, and ultraviolet absorption measurements. A decrease in the association constants of L-tryptophan and diazepam of about 30 - 50% and a decrease in the extrinsic Cotton effects of four benzodiazepine derivatives of about 10 - 15% were found as specific effects of the tryptophan modification. The tryptophan modification itself did not change the number of binding sites of diazepam and L-tryptophan. It is suggested that the lone tryptophan residue of human serum albumin is not directly involved in the specific binding site for indole and benzodiazepine compounds. However, the modification alters the properties of the binding site either by an incomplete refolding of the albumin after urea treatment, or a more selective allosteric effect of the modified tryptophan residue.

2-Hydroxy-5-nitrobenzyl Bromide↗

PubMed1979

Gallium-68 labeling of albumin and albumin microspheres.

Because of the high stability constant of gallium transferrin, the formation of a protein that will be stable in vivo and labeled with gallium-68 (a positron emitter) requires preliminary coupling of a strong chelating group to the protein. In the present study, we have used a reaction developed by Krejcarek and Tucker, in which DTPA is coupled to proteins by the formation of an amide bond. Using human serum albumin (HSA) as a model, we have studied the efficiency of the reaction of HSA with the mixed acid anhydride of the quarternary triethyl ammonium salt of DTPA and butyl formate, as a function of the ratio of albumin to DTPA. After purification of the DTPA-labeled HSA, it is possible to prepare Ga-68-labeled albumin in high yield by chelation of the Ga-68 with the DTPA-labeled protein. In vitro and in vivo stability studies showed that the labeled protein was stable over a period of several hours. The same type of bifunctional chelate has been used to attach Ga-68 to HSA microspheres.

Animals↗

PubMed1979

Antitumor drug-protein interactions. Binding of 1-beta-D-arabinofuranosyl cytosine to albumin and chemically modified albumin.

Equilibrium dialysis measurements were carried out to study the binding of 1-beta-D-arabinofuranosyl cytosine (ara-C) to human and bovine serum albumin (HSA, BSA) and to chemically modified albumin. The binding of 4-phenylbutyric acid to HSA was studied, too. Binding data were presented as Scatchard plots. There are two types of binding sites of different affinity for ara-C both on HSA and BSA. The relatively small value of affinity constant indicates that the pharmacological properties of ara-C might not be influenced very strongly by the HSA interaction or by competitive binding of other drugs. Selective chemical modifications of HSA with diethylpyrocarbonate (DEP) or o-nitrophenylsulfenyl chloride (NPS-Cl) reduce significantly the affinity of the strong binding area. On the other hand, the attachment of poly-alpha-L-glutamyl or poly-DL-alanyl side-chains to BSA increase the number of the strong and secondary binding sites and also the affinity at the first group of sites. Experimental results suggest a correlation between the binding affinity and therapeutic efficacy of various cytotoxic drug-protein complexes.

Animals↗

PubMed1978

Clinical renal preservation by cryoperfusion with an albumin perfusate: renal perfusion with albumin.

Eighty-six human kidneys have been preserved by cryoperfusion with an albumin-based perfusate for five to 50 hours prior to transplantation. Sixty-three of the kidneys were transplanted. The overall immediate function rate was 72% and was 100% (34/34) for kidneys with no warm ischemic damage transplanted into recipients without hypotension or prior sensitivity. The overall actuarial one-month kidney survival rate was 87%, the three-month survival was 73%, and the one-year survival rate was 65%. No kidney was discarded because of poor perfusion. Perfusion data, including flow, dastolic pressure, perfusion time, and lactate concentration were not predictive of immediate renal function. Light, electron, and immunofluorescence microscopic study of biopsy specimens showed no evidence of perfusion or immunologic damage to the kidneys. Perfusion of transplantable kidneys with albumin provides reliable preservation for up to 50 hours without producing either structural or immunologic damage to the organ.

Albumins↗

PubMed1979

Equilibrium saturation chromatographic method for studying the binding of ligands to human serum albumin by high-performance liquid chromatography. Influence of fatty acids and sodium dodecyl sulphate on warfarin-human serum albumin binding.

A size exclusion chromatographic method for studying ligand-macromolecule binding parameters is described. This equilibrium saturation method allows the determination of the concentrations of constituents in equilibrium and is specially useful for characterizing ligand--protein binding under conditions that can be compared with physiological conditions. The method has been used for measuring warfarin--human serum albumin (HSA) binding and for studying the influence of free fatty acids (FFA) and sodium dodecyl sulphate on warfarin--HSA binding. Some comparisons with the Hummel and Dreyer method are given. The influence of the FFA is strongly dependent on their chain length, with an inversion of the effect for a 10-carbon chain.

Chromatography, High Pressure Liquid↗

PubMed1979

Delayed type hypersensitivity to bovine serum albumin and to lipid-conjugated bovine serum albumin in mice.

Delayed type hypersensitivity (DTH) to bovine serum albumin (BSA) and to lipid-conjugated BSA were studied comparatively. Unlike the case of BSA with which no DTH can be detected with native antigen, injection of butyric-conjugated BSA (Bu-BSA) in sensitized mice provokes a typical DTH for an early and limited period. Alum-precipitated Bu-BSA (Al-Bu-BSA) provokes from the beginning a stronger DTH which persists a much longer period.

Alum Compounds↗

PubMed1978

The effects of passive antibodies to egg albumin on active immunity in lambs to Brucella abortus and egg albumin.

The long-term effects of colostrum on active immunity to two unrelated antigens are described. Lambs were fed with pooled colostrum--to equalise passive immunity--with or without added antibodies to egg albumin (Ea). There were significant breed differences in the response both to Brucella abortus measured at one month of age, and to Ea, measured at three months of age, although there was no significant correlation between the responses to the two antigens, either within or between breeds. Surprisingly, whereas antibodies to Ea caused a four-fold reduction in antibody production to B abortus, they did not affect the overall mean response to Ea. But the timing of the response to Ea was significantly affected, suggesting that the low persisting concentrations of antibody had caused qualitative changes in the response.

Animals↗

PubMed1975