Recombinant human insulin.

Insulin is a well-characterized peptide that can be produced by recombinant DNA technology for human therapeutic use. A brief overview of insulin production from both traditional mammalian pancreatic extraction and recombinant bacterial and yeast systems is presented, and detection techniques, including electrophoresis, are reviewed. Analytical systems for insulin separation are principally based on reversed-phase chromatography, which resolves the deamidation product(s) (desamido insulin) of insulin, proinsulin, and insulin. Process-scale separation is a multistep process and includes ion exchange, reversed-phase, and size exclusion chromatography. Advantages and/or disadvantages of various separation approaches, as described by the numerous literature references on insulin purification, are presented.     

Androgens in human evolution. A new explanation of human evolution.

Human evolution consists of chronological changes in gene regulation of a continuous and relatively stable genome, activated by hormones, the production of which is intermittently affected by endogenous and exogenous forces. Periodic variations in the gonadal androgen, testosterone, and the adrenal androgen, dehydroepiandrosterone (DHEA), significantly participated in all hominid transformations. The hominid characteristics of early Australopithecines are primarily a result of increased testosterone. The first significant cold of the early Pleistocene resulted in an increase in DHEA that simultaneously produced Homo and the robust Australopithecines. Subsequent Pleistocene climatic changes and differential reproduction produced changes in DHEA and testosterone ratios that caused extinction of the robust Australopithecines and further changes and continuation of Homo. Changes in testosterone and DHEA produce allometric and behavioral changes that are identifiable and vigorous in modern populations.     

Rethingking human pigmentation.

Though pigmentation has been of interest to anthropologists for a long time, its inheritance, and particularly the reasons for the incomplete correlation of skin, hair and eye, is poorly understood. It is suggested that this is largely due to lack of genetically plausible hypotheses. Taking into account racial and individual variation in pigment traits, and knowledge of pigmentation in other mammals, a minimum set of genetic factors for pigmentation in man is suggested. These include: (1) a set of polygenes affecting skin color only; (2) one locus for depigmentation of the eye, not affecting skin or hair, (3) one pleiotropic gene for reduction of pigment at all sites, and (4) one or more loci with multiple alleles producing blondness or rufosity of the hair in symmetrical patterns over the body.     

Complement-induced histamine release from human basophils. I. Generation of activity in human serum.

The incubation of zymosan, endotoxin, or immune aggregates with normal human serum activates a factor which induces release of histamine from autologous basophils. The reaction can be divided into two steps: in the first, complement must be activated and in the second, the histamine-releasing factor interacts with basophils. The generation of histamine-releasing activity in serum occurs at 17 to 37 degrees C but not at 0 degrees C, is inhibited by heating the serum at 56 degrees C for 30 min, or by the addition of EDTA to the serum. Once generated, the histamine-liberating activity is stable to heating at 56 degrees C for 30 min. Gel filtration of the activated serum demonstrated that this factor eluted in the same region as a factor with chemotactic activity. Both factors have a molecular weight of about 16,000 daltons and their activities were inhibited by antibody to human C5. This is therefore a pathway for histamine release by C5a where the activation of the basophil is unrelated to the membrane bound IgE.     

IgD-receptor-positive human T lymphocytes. II. Identification and partial characterization of human IgD-binding factor.

Membrane receptors specific for IgD (IgD-R) have been identified on murine CD4+ and human CD4+ and CD8+ T lymphocytes. Up-regulation of these IgD-specific receptors can be achieved by exposure of such T cells to various stimuli, including oligomeric or Ag cross-linked IgD, IL-2, IL-4, and T cell mitogens, such as PHA. Previous studies with murine IgD-R+ splenic T cells and IgD-R+ T hybridoma cells have demonstrated the existence of soluble IgD-binding factors (IgD-BF) that are shed or released into the medium in which these cells are grown. In our study, human peripheral blood T cells and IgD-R+ T hybridoma cells were examined for their ability to produce human IgD-BF. PHA stimulation of peripheral blood T cells results in their release of an IgD-specific factor with an apparent Mr of 70 kDa. IgD- Sepharose-purified IgD-BF was able to competitively inhibit rosetting of IgD-R+ T cells with IgD-coated RBC. Immunoblot assays in which alkaline phosphatase-conjugated human IgD myeloma protein was used as a probe, confirmed the IgD specificity of IgD-BF. An IgD-BF-specific mAb (LTB9) that also reacts with membrane IgD-R was produced after immunization of BALB/c mice with this factor. LTB9 was able to detect IgD-BF in the supernatants derived from human IgD-R+, tetanus toxoid-specific T hybridoma cells, H9-CEM1, and to stain membrane IgD-R by indirect immunofluorescence. Stimulation of H9-CEM1 cells with immobilized IgD resulted in up-regulation of membrane IgD-R expression, as measured cytofluorometrically with LTB9-stained cells, and potentiated release of IgD-BF from these cells. Finally, LTB9 as well as IgD-Sepharose, immunoprecipitated a 70-kDa protein from the lysates of biosynthetically labeled H9-CEM1 cells. Similar immunoprecipitation results were obtained with H9-CEM1-derived supernatants containing IgD-BF. Taken together, these results support the hypothesis that human T cell membrane IgD-R are released as soluble IgD-BF.     

Inhibition of human factor IXa by human antithrombin.

A procedure is presented for the purification of Factor IX from human plasma. The final product is homogeneous as judged by disc gel electrophoresis and sodium dodecyl sulfate gel electrophoresis. Furthermore, it is completely free of other coagulation component activities. Factor IX is converted to its enzymatically active form by the addition of small quantities of Factor IXa in the presence of calcium ions. This activated species is added to purified antithrombin-heparin cofactor and the interaction is studied in the presence and absence of heparin. Antithrombin-heparin cofactor is found to be a progressive, time-dependent inhibitor of Factor IXa and neutralizes approximately 57% of this enzyme's proteolytic activity within 30 min. The addition of heparin dramatically accelerates the rate of this interaction with virtually complete inhibition of Factor IXa occurring within 15 s. Sodium dodecyl sulfate gel electrophoresis of reduced and nonreduced proteins indicates that antithrombin-heparin cofactor functions as a potent inhibitor of Factor IXa by forming an undissociable complex with the enzyme which is stable in the presence of denaturing or reducing agents (or both). This complex represents a 1:1 stoichiometric combination of enzyme and inhibitor. Heparin increases the rate of formation of this complex without affecting its dissociability or stoichiometry.     

Immunosuppression by human gangliosides. II. Carbohydrate structure and inhibition of human NK activity.

Gangliosides shed by tumors enhance tumor formation, possibly by suppressing host antitumor immune function, and gangliosides purified from animal tissues and cultured cells inhibit human cellular immune function in vitro. Determination of immunosuppressive activity of highly purified gangliosides, to uncover structure-activity relationships, is therefore important. Here we have studied a series of gangliosides obtained from human tissue and determined their effects on human natural killer (NK) activity. Total gangliosides from human brain tissue were moderately inhibitory; 100 nmol/ml reduced NK activity of human nonadherent PBMC by 43%. The influence of carbohydrate structure upon inhibitory activity was determined by study of eight highly (HPLC) purified individual gangliosides. Of these, we unexpectedly found that the two minor brain gangliosides with the simplest carbohydrate structures, GM2 and GM3, were very active inhibitors (75 and 47%, respectively, at 50 nmol/ml). In contrast, the structurally more complex major species, GM1, GD1a, GD1b, GT1b, and two other minor gangliosides, GD2 and GD3, were inactive. Reduced effector-target binding in a single-cell binding assay by GM2 but not GM3 suggests different mechanisms of inhibition by these two active gangliosides. Since GM2 and GM3 are present in high concentrations in, and are shed by, several common human tumors (e.g., neuroblastoma, melanoma, and glioma), their ability to inhibit NK cytotoxicity supports the hypothesis of a role of shed tumor gangliosides in the enhancement of tumor formation.     

JC human papovavirus replication in human amnion cells.

JC human papovavirus was found to replicate in primary human amnion cells. The virus has undergone eight passages in amnion cells and was identified by serological methods as JC virus. By restriction endonuclease analysis of the viral DNA, the fragments observed were identical to those previously reported for the prototype strain.     

The human loricrin gene.

Loricrin is the major protein component of the cornified cell envelope of terminally differentiated mammalian epidermal (stratum corneum) cells. Using a specific human cDNA clone, we have isolated and characterized the human loricrin gene. We show that it has a very simple structure of a single intron of 1188 base pairs (bp) in the 5'-untranslated region; there are no introns in coding sequences. By use of rodent-human somatic cell hybrids, followed by in situ hybridization with a biotin-labeled genomic DNA clone, the single-copy gene maps to chromosome location 1q21. Polymerase chain reaction analyses of genomic DNAs from different individuals show that human loricrin consists of two allelic size variants, due to sequence variations in its second glycine loop domain, and these variants segregate in the human population by normal Mendelian mechanisms. Furthermore, there are multiple sequence variants within these two size class alleles due to various deletions of 12 bp (4 amino acids) in the major loop of this glycine loop domain. By use of a specific loricrin antibody, we show by immunogold electron microscopy that loricrin initially appears in the granular layer of human epidermis and forms composite keratohyalin granules with profilaggrin, but localizes to the cell periphery (cell envelope) of fully differentiated stratum corneum cells.     

Tocopherol in human platelets.

A spectrophotometric method was used to determine the total tocopherol levels in platelets, plasma, and erythrocytes from human subjects. The platelets contained about three times as much total tocopherol per cell as erythrocytes. This difference was not related to the content of polyunsaturated fatty acids in platelets and erythrocytes. In vitro incubation resulted in significant uptake of tocopherol by plasma and RBC, whereas no uptake was observed into platelets. A 3-month period of tocopherol treatment increased the level of tocopherol in plasma and erythrocytes, whereas the platelet level was unchanged. Tocopherol treatment did not interfere with platelet function or platelet lipid metabolism. The tocopherol fractions of platelets, red cells, and plasma were similar, and alpha-tocopherol was the main fraction.