Studies on Macaca mulatta infected with Rocky Mountain spotted fever

Acid-base alterations and changes in other selected serum constituents (free fatty acids, triglycerides, cholesterol, copper, cortisol, alpha1-acid glycoprotein, haptoglobin, and albumin) were measured during a study of Rocky Mountain spotted fever in 16 male rhesus macaques. Blood samples were taken from nonanesthetized macaques conditioned to repeated handling. Arterial pH increased and PCO2 decreased during the febrile period. Free fatty acids, triglycerides, copper, cortisol, alpha1-acid glycoprotein, and haptoglobin increased, whereas albumin decreased during the disease. Significant changes were not observed in arterial PO2. Cholesterol remained unchanged. The increase in arterial pH and decrease in PaCO2 indicated that respiratory alkalosis was present in macaques acutely affected with Rocky Mountain spotted fever.

A simple method for the separate measurement of transcobalamins I, II, and III: normal ranges in serum and plasma in men and women

A simple method for the separate measurement of the unsaturated binding capacity of the three main circulating vitamin B12 binders, transcobalamins (TCs) I, II, and III, is described. The method involves batch separation of TC I and III from TC II by means of Quso G32, followed by batch separation of TC I from TC II with the use of diethylaminoethyl. The present study provides the first complete comparison of unsaturated TC I, II, and III in serum versus fluoridinated plasma of a single group of normal men versus women. There are consistently higher values in serum, largely due to an in vitro increment of TC III, prevented by NaF. The results are compared with values for some of these parameters obtained by others with the use of different methods, providing a standard for evaluating significance of results by various methods.

The metabolism in man of intravenously injected iodine-labelled trascobalamin I not saturated with cobalamin

Transcobalamin I not saturated with cobalamin was purified. After iodine-labelling, a fraction of approximately 0.6 retained its cobalamin-binding capacity. Iodinated protein was used for turnover studies in three healthy subjects. The plasma curves obtained were identical to those of iodinated transcobalamin I saturated with cyanocobalamin. The cobalamin-binding capacity of the iodinated protein was determined on microcolumns containing insolubilized cobalamin. The binding capacity decreased rapidly, only 50% of the initial unsaturated cobalamin-binding capacity remaining after 0.2 to 0.3 days. It is concluded that the turnover of transcobalamin I not saturated with cobalamin does not differ from the turnover of transcobalamin I saturated with cyanocobalamin, and that transcobalamin I saturated with cobalamin in vivo is metabolized at the same rate as is transcobalamin I saturated with cyanocobalamin in vitro.

Pharmacokinetics and plasma binding of diazepam in man, dog, rabbit, guinea pig and rat

The pharmacokinetics and plasma binding of diazepam were compared in man, dog, rabbit, guinea pig and rat. Diazepam (D) and its major metabolite, desmethyl-diazepam, were measured in blood and plasma by a specific and sensitive gas-liquid chromatography assay with an electron capture detector. After an intravenous bolus injection plasma levels of D declined biexponentially in all species examined and the data were analyzed according to the two-compartment open model. The binding of D and desmethyldiazepam has been determined at therapeutic concentrations by equilibrium dialysis in man (96.8 and 96.6%, respectively), dog (96.0 and 95.9%), rabbit (89.9 and 94.7%), guinea pig (91.3 and 78.6%) and rat (86.3 and 90.5%). In man, the elimination half-life, T1/2(beta), increased significantly (P less than .01) with decreasing total plasma clearance (Cl). Plasma binding affected Vd and Cl, but only Cl increased significantly (P less than .05), if more free D was available. This indicates that unbound drug is rate-determining for clearance by the liver, and that D fits into the restrictive elimination class in man. In the four animal species tested, Cl was a direct linear function of the body surface area. T1/2(beta) and the rates of drug clearance were characteristic figures for each species: from 1.1 hours and 81.6 ml/min/kg in the rat to 32.9 hours and 0.35 ml/min/kg in man, whereas T1/2(alpha), the half-life of distribution, varied only approximately 3-fold (0.3-1.0 hours) in the different species. A considerably higher extraction ratio than the unbound fraction of diazepam exists in these animal species, and blood clearance exceeds liver blood flow, giving reason to assume a much higher ability of the liver to metabolize D, and a species-dependent extrahepatic metabolism. The large variations described suggest that pharmacokinetic data or plasma binding results cannot simply be extrapolated to man.

Interactions of actin, myosin, and an actin-binding protein of chronic myelogenous leukemia leukocytes

Actin, myosin, and a high molecular weight actin-binding protein were purified from chronic myelogenous leukemia (CML) leukocytes. CML leukocyte actin resembled skeletal muscle and other cytoplasmic actins by its subunit molecular weight, by its ability to polymerize in the presence of salts, and to activate the Mg2+-ATPase activity of rabbit skeletal muscle myosin. CML leukocyte myosin was similar to other vertebrate cytoplasmic myosins in having heavy chains and two light subunits. However, its apparent heavy-chain molecular weight and Stokes radius suggested that it was variably degraded during purification. Purified CML leukocyte myosin had average specific EDTA- AND Ca2+-activated ATPase activities of 125 and 151 nmol Pi released/mg protein per min, respectively and low specific Mg2+-ATPase activity. The Mg2+-ATPase activity of CML myosin was increased 200-fold by rabbit skeletal muscle F-actin, but the specific activity relative to that of actin-activated rabbit skeletal muscle myosin was low. CML leukocyte myosin, like other vertebrate cytoplasmic myosins, formed filaments in 0.1 M KCl solutions. Reduced and denatured CML leukocyte-actin-binding protein had a single high molecular weight subunit like a recently described actin-binding protein of rabbit pulmonary macrophages which promotes the polymerization and gelation of actin. Cytoplasmic extracts of CML leukocytes prepared with ice-cold 0.34-M sucrose solutions containing Mg2+-ATP, dithiothreitol, and EDTA at pH 7.0 underwent rapid gelation when warmed to 25 degrees C. Initially, the gel could be liquified by cooling to ice-bath temperature. With time, warmed cytoplasmic extract gels shrunk ("contracted") into aggregates. The following findings indicated that CML leukocyte actin-binding protein promoted the temperature-dependent gelation of actin in the cytoplasmic extracts and that CML leukocyte myosin was involved in the contraction of the actin gels: (a) Cytoplasmic extract gels initially contained actin as their major polypeptide component and consistent of tangled thin filaments; (b) Contracted aggregates of cytoplasmic extract gels contained by large quantities of myosin as well as actin; (c) Purified actin-binding protein underwent a temperature-dependent, reversible aggregation and caused low concentrations of purified muscle or CML leukocyte actins to gel in sucrose solutions; (d) The gels formed from purified actin plus purified actin-binding protein slowly contracted in the presence but not in the absence of purified CML leukocyte myosin; (e) Rabbit antiserum against purified CML leukocyte actin-binding protein but not against purified CML leukocyte myosin inhibited the gelation of warmed CML leukocyte extracts. Antiserum against CML leukocyte myosin had no effect on the gelation of CML leukocyte extracts but partially curtailed the contraction of the CML leukocyte extract gels and of gels formed from purified CML leukocyte actin-binding protein plus rabbit skeletal muscle actin.

[Transcobalamins in megaloblastic anemias]

Transcobalamins are proteins which carry vitamin B12 and which are normally partly unsaturated. This study of transcobalamins was carried out in 17 subjects with megaloblastic anemia (12 true cases of pernicious anemia and 5 cases of folate deficiency). Among the latter, the transcobalamins were studied in 4 cases of pernicious anemia, before and after treatment with vitamin B12. The distribution of endogenous B12 was determined in four normal controls and two cases of pernicious anemia. This vitamin is normally distributed roughly equally between the three transcobalamins, whereas in B12 deficiency, T.C.2 is very unsaturated together with T.C.1 to a lesser degree. The latent fixation capacity of the serum is increased together with the latent fixation capacity of T.C. I and, above all, T.C. II but that of T.C. III is reduced in patients with pernicious anemia. In folate deficiency, only the latent fixation capacity of T.C. II is increased. When vitamin B12 is administered in physiological dosage, T.C. I becomes gradually saturated. In pharmacological dosage, total fixation capacity together with that of T.C. I and T.C. II become gradually reduced, but in spite of high levels of circulating B12, these proteins remain partially unsaturated. Various theories are suggested to explain the variations of these three transcobalamins in megaloblastic anemia but the problem is still unclear.

Lipoprotein fractionation

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