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PubMed2003

Effect of drugs on cholesterol crystallization in an artificial bile model and relation of this effect to drug binding to albumin.

Substances that can affect the crystallization of cholesterol from human bile and consequently the gallstone formation have been given considerable attention. We improved the model system for testing cholesterol crystallization-affecting activity (promoting or inhibiting) of substances and used it for some drugs that are excreted into bile. Besides other factors natural lipid-protein complexes isolated from the native human bile have been shown to be responsible for nucleation and fast crystal growth in cholesterol supersaturated model bile. Artificial lipid-protein complex of taurolithocholate, human serum albumin and Ca2+ (TLTC-HSA-Ca2+) exhibited a lower crystallization activity than both the artificial lipid-protein complexes of taurodeoxycholate, human serum albumin and Ca2+ and the lipid-protein complex isolated from native human bile. The model bile supplemented with this artificial lipid-protein complex (TLTC-HSA-Ca2+) formed a convenient system for testing of various substances (drugs) for their crystallization-affecting activity. From the 20 tested drugs, which could occur at least in small amounts in human bile, the highest crystallization-promoting activity was found for complexes with ampicillin, butorphanol and colchicine. Complexes with tetracycline, thioridazine and doxycycline were the strongest inhibitors. The drugs, which had some effect on cholesterol crystallization, affected somehow the artificial lipid-albumin complex by displacing its components. Interactions of different drugs with HSA and its artificial complexes with the conjugated bile salt and Ca2+ ions were followed by absorption spectroscopy to observe displacement interactions. On the basis of these experiments we could classify drugs into four groups which differ by their effects on spectral characteristics of complexes.

Bile↗
PubMed1998

Direct nucleation of calcium oxalate dihydrate crystals onto the surface of living renal epithelial cells in culture.

BACKGROUND: The interaction of the most common crystal in human urine, calcium oxalate dihydrate (COD), with the surface of monkey renal epithelial cells (BSC-1 line) was studied to identify initiating events in kidney stone formation. METHODS: To determine if COD crystals could nucleate directly onto the apical cell surface, a novel technique utilizing vapor diffusion of oxalic acid was employed. Cells were grown to confluence in the inner four wells of 24-well plates. At the start of each experiment, diethyloxalate in water was placed into eight adjacent wells, and the plates were sealed tightly with tape so that oxalic acid vapor diffused into a calcium-containing buffer overlying the cells. RESULTS: Small crystals were visualized on the cell surface after two hours, and by six hours the unambiguous habitus of COD was confirmed. Nucleation onto cells occurred almost exclusively via the (001) face, one that is only rarely observed when COD crystals nucleate onto inanimate surfaces. Similar results were obtained when canine renal epithelial cells (MDCK line) were used as a substrate for nucleation. Initially, COD crystals were internalized almost as quickly as they formed on the apical cell surface. CONCLUSIONS: Face-specific COD crystal nucleation onto the apical surface of living renal epithelial cells followed by internalization is a heretofore unrecognized physiological event, suggesting a new mechanism to explain crystal retention within the nephron, and perhaps kidney stone formation when this process is dysregulated or overwhelmed.

Animals↗
PubMed2001

Expression of proteins that inhibit calcium oxalate crystallization in vitro in the urine of normal and stone-forming individuals.

The factors precipitating clinically active calcium oxalate (CaOx) urolithiasis are not known. This study examined the relationships between urinary proteins that inhibit CaOx crystallization in vitro and the incidence of CaOx urolithiasis. The first hypothesis is that levels of urinary CaOx crystallization inhibitors differ between clinically active stone formers (SFs) and normal individuals. The second hypothesis is that lower levels of urinary CaOx crystallization inhibitors contribute to the two- to threefold greater incidence of CaOx urolithiasis in males compared with females. These hypotheses were derived from previous observations on the expression of urinary inter-alpha-trypsin inhibitor trimer (IalphaTI-trimer) in normal and stone-forming individuals. The proteins of void urine samples from normal volunteers (24 males, 19 females) and CaOx-SFs (26 males, 16 females) were resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Immunoreactive IalphaTI-trimer, osteopontin, and prothrombin were detected by immunoblot plus enhanced chemiluminescence; the relative densities of the bands were then determined. With the exception of IalphaTI-trimer (P: </= 0.026, approximately twofold), there was no difference in the relative densities of CaOx crystallization inhibitors in the urine of normal and CaOx stone-forming individuals. Thus, there does not appear to be a generalized increase or decrease in levels of CaOx crystallization inhibitory proteins between normal and CaOx stone-forming individuals. The relative density of IalphaTI-trimer was approximately threefold greater in females than in males (P: </= 0.001). Differences in the relative densities of the other CaOx crystallization inhibitors were small and of questionable physiological importance. These data do not support the hypothesis that males have a greater incidence of CaOx urolithiasis because of a generalized decrease in urinary CaOx crystallization inhibitory protein levels.

Adult↗
PubMed2002

Intracytoplasmic immunoglobulin crystals in follicular lymphoma.

We report a case of follicular lymphoma with crystal inclusions. Swollen lymph nodes taken from the left neck of a 53- year-old Japanese woman were replaced by follicular proliferation of atypical centroblastic and centrocytic cells with intracytoplasmic crystal inclusions. The crystals were confined to lymphoma cells and were not found in histiocytes. Lymphoma cells were positively immunostained with lambda light chain and mu heavy chain, but the crystals were only weakly so. In situ hybridization of light chains disclosed a monoclonal expression of lambda light chain mRNA in lymphoma cells. The crystals had a periodic linear substructure with about 5-nm intervals. The worldwide literature reports 8 cases, including the current case of non-Hodgkin's lymphoma with crystals confined to the neoplastic cells. The cases did not accompany paraproteinemia and crystal-storing histiocytosis and appear to follow a favorable clinical outcome.

Crystallization↗
PubMed2002

Bile duct crystals do not contribute to sphincter of Oddi dysfunction.

BACKGROUND: Microlithiasis has been proposed as a cause of both occult gallbladder disease and of idiopathic pancreatitis. Theoretically, microlithiasis could also cause postcholecystectomy pain by causing temporary biliary obstruction and may be more common in patients with sphincter of Oddi dysfunction. The frequency of crystals in bile duct aspirates was assessed from patients with symptoms after cholecystectomy with and without elevated baseline sphincter of Oddi pressures. METHODS: A prospective analysis was performed on all patients with recurrent biliary pain after cholecystectomy who presented for ERCP and manometry between January 1998 and June 2000. All patients had aspirates obtained from the common bile duct for crystal analysis by using the aspirating port of the manometry catheter before the injection of contrast. Four to 20 mL of bile was examined by microscopy for both cholesterol and bilirubinate crystals. RESULTS: Sixty patients (83% women, mean age 44 years) were studied. Thirty-five had normal baseline biliary sphincter pressures and 25 elevated biliary baseline sphincter pressures (>40 mm Hg). Two patients in the normal pressure group and 1 in the elevated pressure group had cholesterol crystals present in their aspirate. No patient had bilirubinate crystals present. A 5% frequency of microlithiasis was identified overall. CONCLUSIONS: Bile duct crystals occur infrequently in patients with symptoms after cholecystectomy and are found in patients with normal and abnormal biliary sphincter manometry. This study suggests that the presence of bile duct crystals, or microlithiasis, does not play a role in sphincter of Oddi dysfunction.

Adult↗
PubMed2006

Manipulating phospholipids for crystallization of a membrane transport protein.

Crystallization is a major bottleneck to obtaining x-ray structures of membrane proteins. By applying an established crystallization protocol for the lactose permease (LacY) of Escherichia coli, a systematic study of the effect of phospholipids (PL) on crystallization of LacY was undertaken. We observe three different crystal forms that diffract to increasingly better resolution in a manner that correlates with the concentration of copurified PL. Consistently, progressive addition of E. coli PL to delipidated LacY leads to different crystal forms. Tetragonal crystals are obtained with improved diffraction quality for a stable mutant by carefully adjusting PL content. Furthermore, crystals of good quality from wild-type LacY, a particularly difficult protein, were also obtained by using same approach. Thus, it is likely that manipulation of PL is a good strategy for predominantly hydrophobic membrane proteins like LacY.

Chromatography, Gel↗
PubMed2006

An approach to crystallizing proteins by synthetic symmetrization.

Previous studies of symmetry preferences in protein crystals suggest that symmetric proteins, such as homodimers, might crystallize more readily on average than asymmetric, monomeric proteins. Proteins that are naturally monomeric can be made homodimeric artificially by forming disulfide bonds between individual cysteine residues introduced by mutagenesis. Furthermore, by creating a variety of single-cysteine mutants, a series of distinct synthetic dimers can be generated for a given protein of interest, with each expected to gain advantage from its added symmetry and to exhibit a crystallization behavior distinct from the other constructs. This strategy was tested on phage T4 lysozyme, a protein whose crystallization as a monomer has been studied exhaustively. Experiments on three single-cysteine mutants, each prepared in dimeric form, yielded numerous novel crystal forms that cannot be realized by monomeric lysozyme. Six new crystal forms have been characterized. The results suggest that synthetic symmetrization may be a useful approach for enlarging the search space for crystallizing proteins.

Crystallization↗
PubMed2003

A defined protein-detergent-lipid complex for crystallization of integral membrane proteins: The cytochrome b6f complex of oxygenic photosynthesis.

The paucity of integral membrane protein structures creates a major bioinformatics gap, whose origin is the difficulty of crystallizing these detergent-solubilized proteins. The problem is particularly formidable for hetero-oligomeric integral membrane proteins, where crystallization is impeded by the heterogeneity and instability of the protein subunits and the small lateral pressure imposed by the detergent micelle envelope that surrounds the hydrophobic domain. In studies of the hetero (eight subunit)-dimeric 220,000 molecular weight cytochrome b(6)f complex, derived from the thermophilic cyanobacterium, Mastigocladus laminosus, crystals of the complex in an intact state could not be obtained from highly purified delipidated complex despite exhaustive screening. Crystals of proteolyzed complex could be obtained that grew very slowly and diffracted poorly. Addition to the purified lipid-depleted complex of a small amount of synthetic nonnative lipid, dioleolyl-phosphatidylcholine, resulted in a dramatic improvement in crystallization efficiency. Large crystals of the intact complex grew overnight, whose diffraction parameters are as follows: 94% complete at 3.40 A spacing; R(merge) = 8.8% (38.5%), space group, P6(1)22; and unit cell parameters, a = b = 156.3 A, c = 364.0 A, alpha = beta = 90 degrees, gamma = 120 degrees. It is proposed that the methodology of augmentation of a well-defined lipid-depleted integral membrane protein complex with synthetic nonnative lipid, which can provide conformational stability to the protein complex, may be of general use in the crystallization of integral membrane proteins.

Crystallization↗
PubMed1984

Crystallization of reaction center from Rhodopseudomonas sphaeroides: preliminary characterization.

Reaction centers (RCs), integral membrane proteins that mediate the conversion of light into chemical energy, were crystallized by two different vapor diffusion techniques. In one method, small amphipathic molecules (1,2,3-heptanetriol and triethylammonium phosphate) were added to the RCs that had been solubilized in detergent. In the second method, crystallization occurred near the phase boundaries of a two-phase system created by the addition of polyethylene glycol and NaCl to RCs in octyl beta-D-glucoside. Several different crystal forms were obtained; two were analyzed by x-ray diffraction. One was monoclinic (space group P2) with beta = 105 degrees, and a = 70 A, b = 105 A, and c = 85 A, two RCs per unit cell, and one RC per asymmetric unit; the crystal diffracted to 3.5 A at 17 degrees C. The other crystal form was orthorhombic (space group C222) with a = 185 A, b = 170 A, and c = 105 A, with eight RCs per unit cell and one RC per asymmetric unit. Reversible light-induced EPR signals of the primary donor (bacteriochlorophyll dimer) showed that the RCs in the crystal were fully active. From the angular dependence of the EPR signal the molecular g anisotropy of the bacteriochlorophyll dimer was deduced to be g perpendicular - g parallel = (64 +/- 3) X 10(-5). Linear dichroism measurements were performed on the monoclinic crystal. The two bands at 535 and 544 nm assigned to the Qx transitions of the bacteriopheophytins were resolved and preliminary orientations of some of the pigments were obtained.

Bacterial Proteins↗
PubMed1991

Monomeric and trimeric forms of photosystem I reaction center of Mastigocladus laminosus: crystallization and preliminary characterization.

Photosystem I (PSI) reaction centers (RCs) of the thermophilic cyanobacterium Mastigocladus laminosus were purified and characterized. The PSI RC was obtained in two forms, monomeric and trimeric. The two forms contained the same number of pigments per P700 and displayed similar photochemical activities. The two forms had nearly identical polypeptide subunit compositions; the only observed difference was an additional subunit of about 12 kDa observed in the trimeric form. The purified preparations of both the monomeric and the trimeric forms were used for crystallization and preliminary crystallographic analysis. The trimeric PSI RC preparations produced several three-dimensional crystal forms, one of which, the "hexagonal needle" form (THN), had a hexagonal unit cell with dimensions of 300 x 300 x 160 A, containing four PSI RC trimers. The monomeric preparations also produced single crystals of several forms under various crystallization conditions. One of these crystal forms, the "hexagonal plate" (MHP), diffracted to a resolution of about 5.5 A. It had a hexagonal unit cell with dimensions of 192 x 192 x 163 A, containing six PSI RC monomers. Comparison of the PSI RCs in the crystals with those in the precrystallization preparations demonstrated that neither the monomeric nor the trimeric form of PSI RC was altered by the crystallization process. Both forms retained their original polypeptide subunit composition and their pigment content.

Blotting, Western↗
PubMed1997

Phosphocitrate inhibits a basic calcium phosphate and calcium pyrophosphate dihydrate crystal-induced mitogen-activated protein kinase cascade signal transduction pathway.

Calcium deposition diseases caused by calcium pyrophosphate dihydrate (CPPD) and basic calcium phosphate (BCP) crystals are a significant source of morbidity in the elderly. We have shown previously that both types of crystals can induce mitogenesis, as well as metalloproteinase synthesis and secretion by fibroblasts and chondrocytes. These responses may promote degradation of articular tissues. We have also shown previously that both CPPD and BCP crystals activate expression of the c-fos and c-jun proto-oncogenes. Phosphocitrate (PC) can specifically block mitogenesis and proto-oncogene expression induced by either BCP or CPPD crystals in 3T3 cells and human fibroblasts, suggesting that PC may be an effective therapy for calcium deposition diseases. To understand how PC inhibits BCP and CPPD-mediated cellular effects, we have investigated the mechanism by which BCP and CPPD transduce signals to the nucleus. Here we demonstrate that BCP and CPPD crystals activate a protein kinase signal transduction pathway involving p42 and p44 mitogen-activated protein (MAP) kinases (ERK 2 and ERK 1). BCP and CPPD also cause phosphorylation of a nuclear transcription factor, cyclic AMP response element-binding protein (CREB), on serine 133, a residue essential for CREB's ability to transactivate. Treatment of cells with PC at concentrations of 10(-3) to 10(-5) M blocked both the activation of p42/p44 MAP kinases, and CREB serine 133 phosphorylation, in a dose-dependent fashion. At 10(-3) M, a PC analogue, n-sulfo-2-aminotricarballylate and citrate also modulate this signal transduction pathway. Inhibition by PC is specific for BCP- and CPPD-mediated signaling, since all three compounds had no effect on serum-induced p42/P44 or interleukin-1beta induced p38 MAP kinase activities. Treatment of cells with an inhibitor of MEK1, an upstream activator of MAPKs, significantly inhibited crystal-induced cell proliferation, suggesting that the MAPK pathway is a significant mediator of crystal-induced signals.

Calcium Phosphates↗
PubMed2000

Preparation and crystallization of dynamic NF-kappa B.Ikappa B complexes.

The formation of single, well-diffracting crystals is a requirement for any molecular structure determination by x-ray crystallography. Crystallization of biological macromolecules can represent a significant obstacle when the subject exhibits internal flexibility or indiscriminate self-association. In such cases, the removal of inherently flexible regions and the addition of stabilizing ligands can improve the probability of crystal formation and ordered growth. We have applied these principles in order to form crystals of the Rel homology region of transcription factor NF-kappaB in complex with its inhibitors IkappaBalpha and IkappaBbeta. None of these molecules crystallizes in the absence of a binding partner. Recombinant overexpression of truncated IkappaBalpha required selection of the correct start site. NF-kappaB.IkappaBalpha complex crystals formed under relatively stringent conditions. NF-kappaB. IkappaBbeta complex crystals were formed by analogy to NF-kappaB. IkappaBalpha, although some modifications in purification and complex formation were necessary due to differences between the inhibitors.

Animals↗
PubMed2002

Crystals of tryptophan indole-lyase and tyrosine phenol-lyase form stable quinonoid complexes.

The binding of substrates and inhibitors to wild-type Proteus vulgaris tryptophan indole-lyase and to wild type and Y71F Citrobacter freundii tyrosine phenol-lyase was investigated in the crystalline state by polarized absorption microspectrophotometry. Oxindolyl-lalanine binds to tryptophan indole-lyase crystals to accumulate predominantly a stable quinonoid intermediate absorbing at 502 nm with a dissociation constant of 35 microm, approximately 10-fold higher than that in solution. l-Trp or l-Ser react with tryptophan indole-lyase crystals to give, as in solution, a mixture of external aldimine and quinonoid intermediates and gem-diamine and external aldimine intermediates, respectively. Different from previous solution studies (Phillips, R. S., Sundararju, B., & Faleev, N. G. (2000) J. Am. Chem. Soc. 122, 1008-1114), the reaction of benzimidazole and l-Trp or l-Ser with tryptophan indole-lyase crystals does not result in the formation of an alpha-aminoacrylate intermediate, suggesting that the crystal lattice might prevent a ligand-induced conformational change associated with this catalytic step. Wild-type tyrosine phenol-lyase crystals bind l-Met and l-Phe to form mixtures of external aldimine and quinonoid intermediates as in solution. A stable quinonoid intermediate with lambda(max) at 502 nm is accumulated in the reaction of crystals of Y71F tyrosine phenol-lyase, an inactive mutant, with 3-F-l-Tyr with a dissociation constant of 1 mm, approximately 10-fold higher than that in solution. The stability exhibited by the quinonoid intermediates formed both by wild-type tryptophan indole-lyase and by wild type and Y71F tyrosine phenol-lyase crystals demonstrates that they are suitable for structural determination by x-ray crystallography, thus allowing the elucidation of a key species of pyridoxal 5'-phosphate-dependent enzyme catalysis.

Catalysis↗
PubMed2005

Crystal structures of the RNA-dependent RNA polymerase genotype 2a of hepatitis C virus reveal two conformations and suggest mechanisms of inhibition by non-nucleoside inhibitors.

Crystal structures of the RNA-dependent RNA polymerase genotype 2a of hepatitis C virus (HCV) from two crystal forms have been determined. Similar to the three-dimensional structures of HCV polymerase genotype 1b and other known polymerases, the structures of the HCV polymerase genotype 2a in both crystal forms can be depicted in the classical right-hand arrangement with fingers, palm, and thumb domains. The main structural differences between the molecules in the two crystal forms lie at the interface of the fingers and thumb domains. The relative orientation of the thumb domain with respect to the fingers and palm domains and the beta-flap region is altered. Structural analysis reveals that the NS5B polymerase in crystal form I adopts a "closed" conformation that is believed to be the active form, whereas NS5B in crystal form II adopts an "open" conformation and is thus in the inactive form. In addition, we have determined the structures of two NS5B polymerase/non-nucleoside inhibitor complexes. Both inhibitors bind at a common binding site, which is nearly 35 A away from the polymerase active site and is located in the thumb domain. The binding pocket is predominantly hydrophobic in nature, and the enzyme inhibitor complexes are stabilized by hydrogen bonding and van der Waals interactions. Inhibitors can only be soaked in crystal form I and not in form II; examination of the enzyme-inhibitor complex reveals that the enzyme has undergone a dramatic conformational change from the form I (active) complex to the form II (inactive).

Amino Acid Sequence↗
PubMed1999

Improved dissolution behavior of fenbufen by spherical crystallization.

Fenbufen is an analgesic, antipyretic and anti-inflammatory drug that is characterized by poor water solubility, a defect increased by very low wettability. Poor water solubility, particularly at low pH, could decrease absorption in the upper part of the gastrointestinal tract, which would be inconvenient for good bioavailability. Different spherical crystallization processes have been considered as methods to improve fenbufen dissolution behavior. A two-solvent system, in the presence of a bridging liquid, is the only method capable of producing spherical fenbufen crystals. In a first step, fenbufen solubility was considered in different solvents. The drug crystals formed were typically needle shaped. This characteristic was considered as a favorable parameter to obtain spherical crystals. After the selection of the best fenbufen solvent, several ratios of solvent (S)-nonsolvent (NS) (tetrahydrofuran [THF]-demineralized water) were studied. The addition of a bridging liquid (isopropyl acetate) improved spherical crystallization. The results from this method were reproducible batch to batch. The spherical crystals obtained showed a clear improvement in dissolution capacity, probably due to better wettability. Dissolution studies were then carried out on these spherical crystals stored for 1 month at different relative humidities (RHs). The dissolution profiles remained unchanged.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2001

Crystal habit modifications of ibuprofen and their physicomechanical characteristics.

Ibuprofen was crystallized from methanol, ethanol, isopropanol, and hexane at similar conditions. Marked differences in crystal habit of the samples obtained from these solvents were observed. The samples crystallized from methanol and ethanol had a polyhedral crystal habit, while those from hexane were needlelike. Those from isopropanol were elongated crystals. X-ray powder diffraction (XPD) and diferential scanning calorimetry (DSC) studies confirmed that these samples were structurally similar, therefore, polymorphic modifications were ruled out. The results showed that crystal habit modification had a great influence on the mechanical properties (compressibility, flow rate, and bulk density) of ibuprofen crystals. Samples obtained from methanol and ethanol exhibited the highest bulk density and the best flow rate, while those from hexane showed the lowest bulk density and the worst flow rate. The samples obtained from ethanol exhibited the best compression force/hardness profiles, and those obtained from hexane produced the softest tablets.

Calorimetry, Differential Scanning↗
PubMed1996

Crystallization of amorphous water ice in the solar system.

Electron diffraction studies of vapor-deposited water ice have characterized the dynamical structural changes during crystallization that affect volatile retention in cometary materials. Crystallization is found to occur by nucleation of small domains, while leaving a significant part of the amorphous material in a slightly more relaxed amorphous state that coexists metastably with cubic crystalline ice. The onset of the amorphous relaxation is prior to crystallization and coincides with the glass transition. Above the glass transition temperature, the crystallization kinetics are consistent with the amorphous solid becoming a "strong" viscous liquid. The amorphous component can effectively retain volatiles during crystallization if the volatile concentration is approximately 10% or less. For higher initial impurity concentrations, a significant amount of impurities is released during crystallization, probably because the impurities are trapped on the surfaces of micropores. A model for crystallization over long timescales is described that can be applied to a wide range of impure water ices under typical astrophysical conditions if the fragility factor D, which describes the viscosity behavior, can be estimated.

Astronomical Phenomena↗
PubMed2001

Effects of Tamm-Horsfall protein and albumin on calcium oxalate crystallization and importance of sialic acids.

BACKGROUND: Tamm-Horsfall protein and human serum albumin are common urinary proteins that show uncertain inhibitory action on the crystallization of calcium oxalate monohydrate. MATERIALS AND METHODS: Batch experiments on crystal nucleation, growth, and aggregation were performed using purified Tamm-Horsfall protein and albumin before and after enzymatic removal of sialic acids from the proteins. RESULTS: At a concentration of 100 nM, both Tamm-Horsfall protein and albumin promoted the time of crystal nucleation by 18.4% and 8.9%, respectively, relative to the control. However, both of the proteins exerted an inhibitory effect on crystal growth, with the IC(50) being 7.27 nM for Tamm-Horsfall protein and 37.5 nM for albumin. The inhibition of crystal aggregation was 81.82% by Tamm-Horsfall protein 100 nM but only 54.55% at 50 nM after enzymatic removal of the sialic acid. Instead of increasing the inhibition, the effect was changed to promotion after an increase in the concentration of Tamm-Horsfall protein to more than 500 nM for native protein and to more than 100 nM for the enzymatic digest. Albumin showed little change after enzymatic treatment and maintained a maximal inhibitory effect of 72.73% on crystal aggregation when the concentration reached to 100 nM. CONCLUSION: Because the promotion of nucleation could lessen the subsequent saturation of a calcium oxalate solution, it is concluded that Tamm-Horsfall protein and albumin show an overall effect of inhibition on crystallization in vitro. The inhibitory effect of Tamm-Horsfall protein is partly related to sialic acid.

Albumins↗