Crystallization of human α-lactalbumin

Crystals of human milk α-lactalbumin have been grown from ammonium sulfate solutions in the presence of calcium ions at 35 °C. They belong to space group P2₁2₁2, with unit cell dimensions: $\text{a = 33.6}\text{A}\text{?}\text{, b = 69.9}\text{A}\text{?}\text{, c = 47.3}\text{A}\text{?}$ and have a single molecule in the asymmetric unit. The crystals diffract X-rays strongly to Bragg spacings of 2 Å and appear suitable for X-ray structural analysis.     

Initiation of human parturition—VII partial characterization of progesterone metabolizing enzymes of human amnion and chorion laeve

The kinetics of the metabolism of progesterone by the reducing enzymes present in the human fetal membranes was evaluated utilizing tissue samples obtained from early and late pregnancies. The specific activities of 5α-reductase, 3β- and 20α-hydroxysteroid oxidoreductase were greater in amnion and chorion laeve tissue obtained from a 16 weeks pregnancy than in those obtained from a 36 1/2 week and from a term pregnancy. Amnion and chorion laeve tissue 20α-hydroxysteroid oxidoreductase enzymes utilized either NADH or NADPH as the source of reducing equivalents (K_m = 0.2–0.3 mM) while amnion tissue 5α-reductase activity required NADPH as the obligatory cofactor (K_m = 0.1mM). The apparent pH optima for the 20α-hydroxysteroid oxidoreductase present in amnion and chorion laeve tissues were similar, while the apparent pH optima for the 5α-reductase enzyme was slightly higher in chorion laeve than in amnion tissue. In 15 min incubations, the apparent maximal activity of amnion 5α-reductase was found at a temperature of 49°C. whereas chorion laeve tissue 3β- and 20α-hydroxysteroid oxidoreductase had maximal activity at 37°C. From progesterone saturation kinetics an apparent K_m of 0.20–0.25 mM for amnion and chorion laeve 20α-hydroxysteroid oxidoreductase, and an apparent K_m of 0.4–1.2 μM for amnion and chorion laeve tissue 5α-reductase activity was computed. Amnion 5α-reductase activity appeared to be particulate in nature.     

Influence of the human blood serum on contractility and β-adrenoreactivity of the isolated human myocardium

Influence of adrenaline (10⁻⁹ to 10⁻⁴ g/ml) on the contraction amplitude caused by electrostimuli (1Hz, 5 ms, 25–30 V) and inotropic and adrenomodulation activities of blood serum of nonpregnant women (at dilutions of 1 : 10 000, 1 : 1000, 1 : 500, 1 : 100, 1 : 50, 1 : 10, and 1 : 5) have been studied. The study has been carried out on isolated myocardium strips of the right atrial auricle that were taken from 43 patients with ischemic illness of the heart and 9 patients with valvular heart diseases of various etiologies upon venous cannula insertion during an aortocoronary bypass. Direct dependence of the contraction amplitude on the cardiac output according to Teicholz has been found. This meant that strips of the right atrial auricle reflected the contractility of the left ventricle myocardium. Adrenaline has been shown to dose-dependently increase the amplitude of evoked contractions in the concentration interval from 10⁻⁷ to 10⁻⁶ g/ml and had no influence from 10⁻⁹ to 10⁻⁸ g/ml (dissociation constant, 2 × 10⁻⁷ g/ml), which proved a decrease in the β-adrenoreceptor’s (β-AR) activation. Blood serum in a dilution range from 1 : 10 000 to 1 : 50 had no effect on the contraction amplitude, but an enhanced effect has been found in a dilution range from 1 : 10 and 1 : 5. The presence of the endogenous activator of myocytes contractility (EAMC) has explained this enhanced effect. The β-adrenomodulation activity of blood serum has been explained by the presence of the endogenous sensitizer of β-AR (ESBAR) and the endogenous blocker of β-AR (EBBAR). The ESBAR activity of blood serum (dilutions: 1 : 1000, 1 : 500, 1 : 100, and 1 : 50) has been found in experiments with a subthreshold adrenaline concentration (10⁻⁸ g/ml). ESBAR (dilutions: 1 : 50 and 1 : 10) and EBBAR (dilution 1 : 500) activities of blood serum have been found in experiments with the maximum effective concentration of adrenaline (10⁻⁶ g/ml). Therefore, blood serum endogenous modulators of β-adrenergic reactivity, ESBAR and EBBAR, can modulate the activation of β-AR of human cardiomyocytes. These prove the prospects of the ESBAR analogue application in cardiology.     

Effect of purified human interferon-α on the expression of differentiation antigens and mitogen reactivity of cultured human thymic cells

Human thymic cells were cultured in vitro either alone or with the addition of a highly purified preparation of human interferon-α. Immunofluorescence techniques using a series of monoclonal antibodies showed that 2-day cultured thymocytes express a more mature phenotype (low HTA 1, high T3 and HLA-A,B,C) than normal, uncultured thymocytes. Interferon addition to the cultures results in a strong increment in the number of HLA⁺ cells and in the total amount of HLA expressed by the cultured cells. Experiments with purified cell populations showed that the cortical, immature, thymocyte was the target cell for interferon action. Phytohemagglutinin responses—but not interleukin 2 responses—were diminished after pretreatment of thymic cells with interferon. We suggest that interferon may favor a pathway of intrathymic differentiation phenotypically characterized by a high content of Class I HLA antigens.     

Full-size form of human liver AMP-deaminase?

AMP-deaminase from human liver was purified by two-step phosphocellulose chromatography, and SDS-PAG electrophoresis of the most active enzyme fraction eluted has been performed. The largest of the protein fragments revealed had a size (92 kDa) of an apparent full-size enzyme subunit, and reacted positively with antibodies produced against specific human ampd2 gene product. Three-day storage at cold room temperature modified significantly the electrophoretical pattern of the enzyme, evidencing continuous and progressive degradation of its structure. This is a first report evidencing the presence of apparent full-size form of human liver AMP-deaminase in preparation obtained from endogenous source.     

Chromosome preparations of human blood lymphocytes—Evaluation of techniques

Several parameters of human lymphocyte culturing techniques and metaphase chromosome preparation procedures were studied and quantitatively evaluated in regard to their influence on the results of Q and G banding procedures. The culturing conditions were studied using³H thymidine incorporation as a parameter. A whole blood culturing technique using Ham's F12 medium was found to give optimal and consistent results. Colcemid concentration proved to be of no influence on chromosome contraction or on the number of metaphases obtained over the concentration range investigated. Prolonged exposure to colcemid was found to cause a decrease in the mean chromosome length but the absolute number of metaphases with a low degree of chromosomal contraction hardly decreased. Different spreading techniques were quantitatively analysed and factors important for the spreading of chromosomes were evaluated. Based on the results obtained, an optimal procedure is described which over a period of one year has given consistent results.     

Is vitellogenin an ancestor of apolipoprotein B-100 of human low-density lipoprotein and human lipoprotein lipase?

Vitellogenin, an ancient animal protein, is the major yolk protein of eggs, where it is used as a food source during embryogenesis. Here it is shown that vitellogenins, including those from the invertebrates Caenorhabditis elegans and Drosophila melanogaster, contain domains that are homologous with parts of apolipoprotein B-100 (apoB-100) of human low-density lipoprotein and human lipoprotein lipase. As vitellogenins are likely to have been used by invertebrates during embryogenesis well before the circulation of lipids appeared in vertebrates, it is suggested that copies of a precursor gene, serving a function similar to vitellogenin, were modified to code for part of apoB-100 and lipoprotein lipase in vertebrates. In addition to providing a link between invertebrates and vertebrates for proteins involved in lipid transport, these homologies suggest new functions for vitellogenin other than being a yolk food for the developing embryo.     

Effect of human endothelial cells on human bone marrow stromal cell phenotype: role of VEGF?

Angiogenesis is a tightly regulated process involved in growth, repair, and bone remodeling. Several studies have shown that there is a reciprocal regulation and functional relationship between endothelial cells and osteoblast-like cells during osteogenesis, where systemic hormones and paracrine growth factors play an active role. Angiogenesis is induced by a variety of growth factors; among them vascular endothelial growth factor (VEGF) may be an important mediator for the angiogenic process involved in bone physiology. We studied the VEGF effect on osteoblast progenitor cells (Human Bone Marrow Stromal Cells: HBMSE) cultured alone or associated with endothelial cells (Human Umbilical Vein Endothelial Cells: HUVEC) in different co-culture models (co-culture with or without direct contact, conditioned medium), to determine the influence of VEGF on these cells and on their relationship. In agreement with other studies, we show that HBMSC express and synthesize VEGF, HUVEC conditioned medium has a proliferative effect on them, and early osteoblastic marker (Alkaline phosphatase activity) levels increase when these cells are co-cultured with HUVEC only in direct contact. However, unlike previous studies, we did not find that VEGF increased these processes. These results suggest that the intercommunication between endothelial cells and osteoblastic-like cells requires not only diffusible factors, but also involving cell membrane proteins.     

Origin of the multiple components of human α1-antitrypsin

Multiple components of human ₁-antitrypsin were separated by preparative starch gel electrophoresis, and the sialic acid contents of these components were determined. The acidic components contained more sialic acid per molecule than the basic components. The molecular sizes of these components were identical, excluding the possibility of polymerization of the inhibitor in the formation of the multiple components. Consequently, the multiple components of the inhibitor are primarily due to differences in the sialic acid content of each component. Three major components contain eight, seven, and six sialic acid residues per molecule, respectively.This work was supported by Grant HL-17535 from the National Institutes of Health.     

Are human beings part of the rest of nature?

Unified explanations seek to situate the traits of human beings in a causal framework that also explains the trait values found in nonhuman species. Disunified explanations claim that the traits of human beings are due to causal processes not at work in the rest of nature. This paper outlines a methodology for testing hypotheses of these two types. Implications are drawn concerning evolutionary psychology, adaptationism, and anti-adaptationism. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genes for the ‘H’ subunit of human ferritin are present on a number of human chromosomes

Summary DNa has been extracted from hamster-human and mouse-human hybrid cell lines, restricted with EcoRI, and hybridised to a probe for the H subunit of human ferritin, pDBR2. Sequences highly homologous to this probe have been found on at least eight human chromosomes: 1, 2, 3, 6p216cen, 11, 14, 20, and Xq23–25Xqter. Only the gene on chromosome 11 appears to be expressed in these hybrids Southern blotting of DNA from somatic cell hybrids containing different subsets of human chromosomes. The study shows that H subunit sequences are found on at least nine different chromosomes.     

Role of A-chain in functioning of the active site of human α-thrombin

This review summarizes current data suggesting that A-chain of the human alpha-thrombin molecule plays a role of allosteric effector in catalytic reactions with various substrates. Special attention is paid to the relationship between A-chain structure and catalytic activity of thrombin. The existence of this relationship is based on studies of natural mutation of A-chain of the alpha-thrombin molecule. Use of molecular and essential dynamics confirmed the role of A-chain in changes of conformation and catalytic properties of this enzyme; these changes involve residues located in the specificity sites and some inserting loops. Current knowledge on structure and properties of thrombin can be used for the development of new antithrombin agents.     

Investigation of the early stages of human γD-crystallin aggregation process

Cataract, a major cause of visual impairment worldwide, is a common disease of the eye lens related to protein aggregation. Several factors including the exposure of ultraviolet irradiation and possibly acidic condition may induce the unfolding and subsequent aggregation of the crystallin proteins leading to crystalline lens opacification. Human γD-crystallin (HγDC), a 173 residue monomeric protein, abundant in the nucleus of the human eye lens, has been shown to aggregate and form amyloid fibrils under acidic conditions and that this aggregation route is thought to be a potential initiation pathway for the onset of age-related nuclear cataract. However, the underlying mechanism of fibril formation remains elusive. This report is aimed at examining the structural changes and possible amyloid fibril formation pathway of HγDC using molecular dynamics and molecular docking simulations. Our findings demonstrated that incubation of HγDC under the acidic condition redistributes the protein surface charges and affects the protein interaction with its surrounding solvent environment. This brings about a twist motion in the overall tertiary structure that gives rise to newly formed anti-parallel β-strands in the C-terminal flexible loop regions. The change in protein structural conformation also involves an alteration in specific salt-bridge interactions. Altogether, these findings revealed a plausible mechanism for amyloid fibril formation of HγDC that is important to the early stages of HγDC aggregation involved in cataractogenesis.     

Expression of human β-defensin-2 gene induced by CpG-DNA in human B cells

Defensins have a broad range of antimicrobial activity against bacteria, fungi, and viruses. The expression of human β-defensin-2 (hBD-2) is prevalently observed in epithelial cells and is induced by bacterial infection. Here, we have shown that the expression of the hBD-2 gene and release of hBD-2 protein into the medium is up-regulated in response to CpG-DNA in human B cell line RPMI 8226. The induction of hBD-2 was dependent on CG sequence and phosphorothioate backbone-modification. This was also confirmed in primary human lymphocytes. To shed light on the molecular mechanism involved in hBD-2 induction by CpG-DNA, we examined the contribution of the NF-κB signaling pathway in RPMI 8226 cells. Suppression of MyD88 function and inhibition of NF-κB nuclear localization blocked hBD-2 induction. The NF-κB pathway inhibitors also abolished hBD-2 induction. These results may contribute to a better understanding on the therapeutic effects of CpG-DNA against infectious diseases.     

Production of human platelet lysate by use of ultrasound for ex vivo expansion of human bone marrow–derived mesenchymal stromal cells

Background aimsA medium supplemented with fetal bovine serum (FBS) is of common use for the expansion of human mesenchymal stromal cells (MSCs). However, its use is discouraged by regulatory authorities because of the risk of zoonoses and immune reactions. Human platelet lysate (PL) obtained by freezing/thawing disruption of platelets has been proposed as a possible substitute of FBS. The process is time-consuming and not well standardized. A new method for obtaining PL that is based on the use of ultrasound is proposed.MethodsPlatelet sonication was performed by submerging platelet-containing plastic bags in an ultrasonic bath. To evaluate platelet lysis we measured platelet-derived growth factor-AB release. PL efficiency was tested by expanding bone marrow (BM)-MSCs, measuring population doubling time, differentiation capacity and immunogenic properties. Safety was evaluated by karyotyping expanded cells.ResultsAfter 30 minutes of sonication, 74% of platelet derived growth factor-AB was released. PL enhanced BM-MSC proliferation rate compared with FBS. The mean cumulative population doubling (cPD) of cells growth in PL at 10%, 7.5% and 5% was better compared with cPD obtained with 10% FBS. PD time (hours) of MSCs with PL obtained by sonication was shorter than for cPD with PL obtained by freezing/thawing (18.9 versus 17.4, P < 0.01). BM mononucleated cells expressed MSC markers and were able to differentiate into adipogenic, osteogenic and chondrogenic lineages. When BM-MSCs and T cells were co-cultured in close contact, immunosuppressive activity of BM-MSCs was maintained. Cell karyotype showed no genetic alterations.ConclusionsThe proposed method for the production of PL by sonication could be a safe, efficient and fast substitute of FBS, without the potential risks of FBS.     

Transport of poly-β-hydroxybutyrate in human plasma

Poly-β-hydroxybutyrate (PHB) is an amphiphilic lipid that has been found to be a ubiquitous component of the cellular membranes of bacteria, plants and animals. The distribution of PHB in human plasma was investigated using chemical and immunological methods. PHB concentrations proved highly variable; in a random group of 24 blood donors, total plasma PHB ranged from 0.60 to 18.2 mg/l, with a mean of 3.5 mg/l. In plasma separated by density gradient ultracentrifugation, lipoproteins carried 20–30% of total plasma PHB; 6–14% in the very low density lipoproteins (VLDL), 8–16% in the low density lipoproteins (LDL), and < 3% in the high density lipoproteins (HDL). The majority of plasma PHB (70–80%) was found in protein fractions of density > 1.22 g/ml. Western blot analysis of the high density fractions with anti-PHB F(ab')₂ identified albumin as the major PHB-binding protein. The affinity of albumin for PHB was confirmed by in vitro studies which demonstrated transfer of ¹⁴C-PHB from chloroform into aqueous solutions of human and bovine serum albumins. PHB was less tightly bound to LDL than to other plasma components; the polymer could be isolated from LDL by extraction with chloroform, or by digestion with alkaline hypochlorite, but it could not similarly be recovered from VLDL or albumin. PHB in the LDL correlated positively with total plasma cholesterol and LDL cholesterol, and negatively with HDL cholesterol. The wide concentration range of PHB in plasma, its presence in VLDL and LDL and absence in HDL, coupled with its physical properties, suggest it may have important physiological effects.     

Epigenetics of human melanoma： promises and challenges

Melanoma is the deadliest form of skin cancer with rising incidence and mortality rates. Although early-stage melanoma is highly curable, advanced-stage melanoma is refractory to treatment. This underscores the importance of prevention and early detection as well as the need to improve treatment and prognostication of human melanoma. Elucidating the underlying mechanisms of the initi- ation and progression of human melanoma can help identify potential targets of intervention for prevention, diagnosis, therapy, and prognosis of this disease. Aberrant DNA methylation and histone modifications are the best-established epigenetic mechanisms of carcinogenesis. The occurrence of epigenetic changes prior to clinical diagnosis of cancer and their reversibility through pharmaco-logic/genetic approaches offer a promising avenue for basic and translational research on human melanoma. Candidate gene（s） or genome-wide aberrant DNA methylation and histone modifications have been observed in human melanoma tumor tissues and cell lines, and correlated to cellular and functional characteristics and/or clinicopathologicai features of this malignancy. The present review summarizes the published researches on aberrant DNA methylation and histone modifications in connection with human melanoma. Representative studies are highlighted to set forth the current state of knowledge, gaps in the knowledgebase, and future directions in these epigenetic fields of research. Examples of epigenetic therapy applied for human melanoma in vitro, and the challenges of its in vivo application for clinical treatment of solid tumors are discussed.