Essential metal ions alter the lactoferrin binding to the erythrocyte plasma membrane receptors.

The effect of metal ions at a concentration of 10(-8) to 10(-5) M [using their salts: ZnCl2, CdCl2, LiCl, CuSO4, NiSO4, Al2(SO4)3, (NH4)2MoO4 on the lactoferrin (Lf) binding to the erythrocyte membrane receptors was studied. In the absence of metal ions, Scatchard's analysis showed the existence of two kinds of binding site: one with high affinity and low capacity, and the another with low affinity and high capacity. All these metals, excluding Zn2+ and Cd2+, at a concentration 10(-5) M decreased the affinity of Lf binding (Ka1) to the high-affinity receptors.

Effect of lactoferrin on the phagocytic activity of polymorphonuclear leucocytes isolated from blood of patients with autoimmune diseases and Staphylococcus aureus allergy.

Phagocytic number (PN) and phagocytic index (PI) of neutrophils isolated from blood of patients with autoimmune diseases, allergy to Staphylococcus aureus and from blood of healthy individuals were examined. Our results concerning the influence of lactoferrin (Lf); (6.7 mg/l) on the PI of PMN showed that: 1) Lf enhances reliable PI of PMN at the 30-th minute starting the phagocytic reaction in patients with autoimmune disease in an active stage, in blood donors treated as healthy with the presence of autoantibodies, in patients with autoimmune diseases and proved autoantibodies against tissue, cell antigens and collagen, 2) Lf influences non-significantly PI of PMN in patients with autoimmune collagen diseases in remission, 3) Lf increases PI of PMN with 19% only in 58% from the assessed patients with Staphylococcus aureus, and 4) Lf decreases non-significantly PI of PMN in the healthy controls.

Influence of ascorbic acid, sodium citrate, and sodium bicarbonate on the uptake of 59Fe-transferrin, 54Mn-transferrin, and 65Zn-transferrin from lactating mouse mammary gland cells.

The effects of ascorbic acid, sodium citrate, and sodium bicarbonate on 59Fe-transferrin, 54Mn-transferrin, and 65Zn-transferrin uptake by the receptors disposed of plasma membrane isolated from lactating mouse mammary gland cells have been investigated. The effect of 10(-2) mol/L ascorbic acid alone and in combination with NaHCO3 on the 59Fe-transferrin uptake is significant and positive. 54Mn-transferrin and 65Zn-transferrin binding to the cell receptors are influenced optimally by 0.

The competition between transferrins labeled with 59Fe, 65Zn, and 54Mn for the binding sites on lactating mouse mammary gland cells.

Using a homologous competition of 54Mn-transferrin with Mn-transferrin and 65Zn-transferrin with Zn-transferrin, it was found that on the plasma membrane of lactating mouse mammary gland cells there are receptor binding Mn-transferrin and Zn-transferrin. The heterologous competition between labeled and nonlabeled Fe-transferrin, Mn-transferrin and Zn-transferrin, as well as almost equal affinity constants of cellular receptors toward the three metals by competition of Fe-transferrin suggests that one and the same receptor accepts all three metals from the transferrin molecule. The cell receptors therefore possess a polymetal binding function.

[The determination of the somatostatin content in insulin substances].

30 different lots (batches) of insulin substances ("Pharmachim" Ltd.) are analysed and the contents of somatostatin is established. The middle quantitative values and the standard deviations are specific.

[Radioimmunological determination of glucagon in Bulgarian insulin substances].

The contents of glucagon in insulin substances ("Pharmachim" Ltd.) is determined in accordance to the needs of pharmaceutical production. The middle quantitative values and standart deviation are specified.

Effect of bovine milk antigens and egg lysozyme on the binding of 59Fe-lactoferrin to platelet plasma membranes.

1. Platelets bind specifically to lactoferrin. A significant similarity between human lactoferrin and some bovine milk proteins has been established.

Lactoferrin binding to human platelets.

1. Platelets bind specifically lactoferrin. 2.

[Problem solving of the clinical case-method type for the development of clinical thinking. The illustrative problem of galactosemia].

Problem-solving case approach is an effective method for teaching clinical concepts. This method makes medical students be aware of the significance of Biochemistry for the clinical practice. The students are stimulated to study basic biochemical principles.

[Vasopressin as a neurotransmitter and neuromodulator].

Recent data about the antidiuretic hormone arginine vasopressin (AVP) are reviewed which show that except its well known peripheral endocrine functions, it has another not less important function as a neurotransmitter and neuromodulator in the central nervous system. AVP facilitates learning and memory consolidation. Data are also presented about the primary structure of AVP precursor and the sites of its synthesis, as well as about the AVP receptors and the mechanism of its action in different brain areas.

[The radioimmunological determination of porcine pancreatic polypeptide in Bulgarian insulin substances].

The contents of pancreatic polypeptide in insulin substances ("Pharmachim" Ltd) is determined in accordance to the needs of pharmaceutical production. The analysed insulin substances pertain to groups of different purity. The results, showing distribution of middle value of pancreatic polypeptide are discussed.

[The determination of the biological activity of insulin by a radioreceptor method].

A new in vitro radioreceptor assay method for determining the biological activity of insulin substances is put forward. This method is designed mainly to serve the purposes of practice. It perfectly substitutes the biological, expensive labour-taking and slow pharmacopoeial method.

[The preparation of materials and the isolation of human genomic DNA for analysis].

The work reviews the usual and most convenient human samples (blood cells, fibroblasts, etc.) for extraction of DNA, storage conditions, DNA extraction approaches, and the criteria for assessment of quality and suitability of the extracted DNA for subsequent analysis. The aim of this work is to make professionals from different laboratory disciplines aware of the basic approaches to DNA sampling and storage in order to promote their further involvement in diagnostics and research based on DNA technology.

Competition of Mn2+ and Zn2+ with 59Fe2+ and 59Fe3+ for the plasma membrane receptors from lactating mouse mammary gland.

Nonlabeled MnCl2 and ZnSO4 compete with 59Fe(2+)-ascorbate and 59Fe2(3+)O3 for transport binding sites situated on the plasma membranes of lactating mouse mammary gland cells. The binding was found to be a process reaching saturation. The heterologous competition used here ruled out the participation of transferrin and to propose that Fe, Mn, and Zn are transported from blood to milk by a mechanism involving one receptor during lactation.

Effect of insulin and adrenaline on the 59Fe transferrin uptake of lactating mouse mammary gland cells.

The results of insulin action (0.4 IU per mouse) are demonstrated in intact animals only. This action leads to a higher uptake of 59Fe.

Binding of mouse and rabbit iron-59 transferrins to lactating mouse mammary epithelial cells.

The binding of mouse and rabbit transferrins to lactating mouse mammary epithelial cells was tested in a 59Fe-protein-binding assay. The homologous and heterologous binding was slow during the first 30 min, after which the uptake steadily increased. In ligand concentration-dependent saturation studies, the heterologous rabbit protein showed a high degree of binding and required approximately 9.

Effect of ascorbic acid, sodium citrate, sodium bicarbonate, and their combination effect on the binding of 59Fe2+ and 59Fe3+ to plasma membrane of lactating mouse mammary gland.

Isolated plasma membranes of lactating mouse mammary gland were treated with different concentrations of ascorbate, sodium citrate, sodium bicarbonate, and combinations of them (from 16 x 10(-10) to 4 x 10(-6) moles/L) and studied for the binding of 59Fe2+ and 59Fe3+ at pH 7.4. The results show that the Fe3+ form of iron is under a greater influence of anions used in these experiments.

Lactating mouse mammary cell uptake of 59Fe-transferrin. The effect of KCN, 2,4-dinitrophenol, ethanol and ATP.

1. Amounts of KCN of 0.2, 1.

The difference between cytosol and membrane growth-related protein kinase activities in lactating mouse mammary gland.

1. A protein kinase activity which is cAMP-independent, inhibited by the bioflavonoid quercetin and probably connected to the growth of mammary gland cells was isolated and partially purified from cytosol. 2.

A program package for self-assessment and examination in biochemistry.

A BASIC program has been developed for self-evaluation and testing of an individual's knowledge of main categories in biochemistry. The computer tests permit sequential or random distribution of items, random distribution of answers in each item at each new run, effective feedback control with the student, use of a program clock to determine different time allowance, precise and quick analysis and grading of student's answer thus saving the time and labour of examiners. Editing, deleting and appending of new items is easily achieved.

Opiate receptor binding in the brain of rat during stress.

Two types of opioid receptors were studied in the brain of rats: Delta (for endogenous opiate) and mu (for exogenous opiates). 3H derivates: D-Ala2-enkephalin and Naloxone were used as labeled ligands. The results obtained were calculated by computer program for automatic estimation of the data using approximation equations.