Dietary titanium and infant growth.

Dietary titanium as TiO2+ improved animal growth during infancy while inhibiting the metabolism of intestinal bacteria. TiO2+ was also found capable of inhibiting human cytomegalovirus in tissue culture. These and other findings indicate TiO2+ improves infant growth by acting as an antibacterial and antiviral agent. The behavior of TiO2+ stands in contrast to that of TiO2, which is inert.

Biological roles of titanium.

Ti4+ in soil is a natural antibiotic mobilized by bacteria-generated H+. When added to the diet of young mice, Ti4+ enhanced their growth. These and observations of others indicate that Ti4+ has a variety of biological roles.

Transition metals as protease inhibitors.

An alternative approach to the development of clinically useful protease inhibitors was investigated. The approach utilized coordination chemistry of transition metal ions rather than substrate analogs to block active sites of these enzymes. In the case of serine proteases it was found that aqueous Ti(IV) is a potent inhibitor of the trypsin subclass, but not the chymotrypsin subclass. The direct binding of Ti(IV) to trypsin was made possible by the presence of a free carboxyl group at the bottom of the substrate binding pocket of the enzyme, and the five-coordinate geometry of TiO(SO4)(H2O). Although initial binding of Ti(IV) was reversible, it was followed in time by irreversible inhibition. Direct binding of octahedral or tetrahedral metal ion complexes was prevented by the inability of the enzyme active sites to promote formation of a five-coordinate transition state of the metal ion required for reaction. These studies demonstrate the ability of direct metal ion binding as a way to enhance blocking of enzyme active sites as compared with that of traditional organic inhibitors. Application of these findings was investigated by measuring the affect Ti(IV) had on growth of Escherichia coli, Salmonella typhimurium, and Pseudomonas aeruginosa. Five-coordinate titanyl sulfate completely inhibited the growth of these organisms. This suggests that five-coordinate titanyl sulfate, which is easier and less expensive to manufacture than conventional antibiotics, may be useful in controlling endemic infections of E. coli and S. typhimurium.

Changes induced in antibodies by isolation methods.

IgG was isolated from plasma at low temperatures using the Cohn fractionation method, and then processed to three different products in order to evaluate how chemical and physical manipulations affect antibodies. Evaluation of the antibodies was done by measuring their ability to bind human immunodeficiency virus, cytomegalovirus, Herpes simplex virus, and rubella virus. In addition, the IgG products were compared by crossed immunoelectrophoresis, and circular dichroism and ultra violet spectroscopy. It was found that exposure of purified IgG to physiological pH altered the molecular conformation of IgG and induced various degrees of irreversible loss in antibody binding to viruses. These observations indicate that more efficacious antibodies may be obtained for clinical use if isolation at their isoelectric point is avoided.

Three generations of immunoglobulin G preparations for clinical use.

The first purified human immunoglobulin G (IgG) preparation used clinically was immune serum globulin (ISG), which was prepared in the 1940s by E. J. Cohn's group. It was originally formulated in water with 0.3 M glycine at pH 6.8 and was 70%-80% monomeric. ISG was safe when given intramuscularly and efficacious for measles and hepatitis prophylaxis. The next generation of purified IgG began in the 1960s with chemically modified preparations suitable for intravenous administration. The first such IgG intravenous preparation (IGIV) in the United States was IGIV pH 6.8 (Gamimune, Cutter Biological), in which the anticomplement activity found in ISG was removed by reduction and alkylation of disulfide bridges. This product was originally formulated as a 5% IgG solution in water (pH 6.8) with 0.2 M glycine in 10% maltose for stabilization. It remained stable for at least 2.5 years at 5 degrees C, was 80%-90% monomeric, had virtually no anticomplement activity, was safe given intravenously, and was efficacious for prophylaxis in agammaglobulinemic patients. A third generation of purified IgG has since been developed; IGIV pH 4.25, (Gamimune N, Cutter Biological), which was isolated by the Cohn method from human plasma and is safe for intravenous use, is a 5% solution of IgG in water (pH 4.25) with 10% maltose. The product is greater than 99% IgG, greater than 95% monomeric, and has greater than 90% less anticomplement activity than ISG.

Principles & Practices Board remains a valuable resource to members. Interview by Karen Hackett.

In this interview, Joseph P. McCue, FHFMA, CPA, chairman of HFMA's Principles & Practices Board, discusses the history and activity of the Board since its start in 1975. According to McCue, the Board was originally formed to address the technical accounting and reporting questions unique to the healthcare industry, and nothing has changed HFMA's opinion that such a mission is still important--the necessity for a P&P Board is as acute now as it was in 1975. The interviewer is Karen Hackett, CMPA, an HFMA staff liaison with the Board.

Changes in red blood cell membrane phosphate concentration during blood bank storage.

The change in red blood cell membrane phosphate concentration of standard CPD whole blood stored in Fenwal blood bags at 4 C was measured daily for two weeks. Membrane phosphate concentrations increased rapidly when stored pH fell to 6.95. At the same time, the rate of K+ leakage from the cells increased, and transport of inorganic phosphate across the membrane decreased. It is concluded that gross uptake of phosphorus by the red blood cell membrane during blood bank storage may be in part responsible for physical changes in the membrane.

Platelet lesion of collection.

In the early stages of blood collection for transfusion, whole blood is subjected to trauma from the anticoagulant. The blood--anticoagulant mixture does not attain a pH at which platelets can remain functional (approximately pH 6.0) until about 25% of the unit has been collected. We have examined platelet ultrastructure and in vitro aggregation responses to adenosine diphosphate (ADP) and epinephrine (EPN), to assess the platelet trauma of collection into citrate-phosphate-dextrose. For comparison blood was collected by 2 methods: one was conventional (CC), the other metered anticoagulant into the blood as it was collected (MC). Platelets from CC blood showed disruption of organelles and depletion of the dense bodies, whereas platelets from MC blood showed no ultrastructural damage. In addition, biphasic aggregation in response to ADP or EPN was seen in MC platelets but not in CC platelets.

Changes in oxygen radical scavenging by human blood cell lysates concurrent with viral infections.

The higher superoxide dismutase (SOD) levels found in human blood cells when Nitro Blue Tetrazolium (NBT) rather than Cytochrome C was used as the colorimetric detector of superoxide (O-2) was investigated. the NBT was found to react with oxygen radicals other than O-2, thus providing measurement of total oxygen radical scavenging ability. Also investigated was the biomodal distribution of SOD activity in lymphocytes and granulocytes from a randomly selected human populace. Human lymphocytes rapidly increased their SOD activity by two- to four-fold during respiratory viral distress. The response to certain infections was probably responsible for the bimodal distribution of SOD activity in the general populace. It was concluded that the chemical events that prepare lymphocytes and granulocytes for their role in defense against infections begin long before these cells are sequestered from circulation by the infections.

Reversal of the storage lesion of CPD bank blood: a problem in clinical medicine.

The effect of phosphate buffer on the course of pH, ATP, and 2,3-PDG of CPD red blood cells stored at three temperatures was observed. Basic phosphate at an equilibrated level of 10 mM (as iP) maintained pH above 7.00 and ATP and 2,3-DPG above 70 per cent of initial value in cells stored at 37 C for 24 hours. In contrast however, at 25 and 4 C no buffering was obtained with basic phosphate concentrations up to 50 mM, but values for both ATP and 2,3-DPG were higher in phosphate treated aliquots than in controls throughout storage. When the pH of blood stored at 4 C was adjusted into the range 7.15 to 7.25 with tromethamine and the level of iP raised to 10 mM by addition of Na2HPO4 on day seven, it was found that ATP and 2,3-DPG levels were maintained at 90 and 120 per cent, while control levels fell to 60 and 12 per cent, respectively at 21 days. The process described parallels the normal repair of damaged red blood cells of bank blood that occurs in vivo following transfusion.

Oxidation of procarbazine in the presence of Ti(IV).

The air oxidation of procarbazine in the presence of Ti(IV) was examined as a model system for the effects titanium has on oxidative processes and intermediates involving molecular oxygen. It was found that Ti(IV) inhibited oxidation when the substrate, procarbazine, was coordinated to titanium. This inhibition was most prominent (reduction of overall rate constant by a factor of 10(2)) in its interference with Cu(II) catalyzed oxidation of the substrate whole oxidation by the neutral species O2 was only slightly inhibited (factor of 2). However, when Mn(II) was used to catalyze the oxidation of procarbazine by air, titanium enhanced the catalytic effect of Mn(II) by a factor of 10(2). This enhancement was found to be due to Ti(IV) catalysis of the air oxidation of Mn(II), and the effect was found to be inhibited by catalase but not superoxide dismutase or peroxidase. These results are discussed in terms of a Ti(IV) ability to activate molecular oxygen and its ability to form oxygen free-radical complexes.