Pharmacokinetics and metabolism of fosmidomycin, a new phosphonic acid, in rats and dogs

The absorption, distribution, metabolism, and excretion of 3-(N-formylhydroxylamino) propylphosphonic acid monosodium salt (fosmidomycin), a new antibiotic, were investigated in rats and dogs after i.v. and oral dosing. After i.v. administration of 10 mg/kg of body weight, [14C]-fosmidomycin was excreted mainly in the urine (about 90% of dose within 72 h); and only a little was excreted in the expired air (14CO2) and bile of rats (less than 1% of dose), which suggested the absence of enterohepatic circulation. After oral administration of 10 mg/kg of body weight to rats, 34% and 61% of dose were excreted in the urine and faeces, respectively, suggesting about 30% gastro-intestinal absorption. No metabolites were found by autoradiography of the urine after thin layer chromatography. Radioactivity levels in the serum essentially agreed with the unchanged fosmidomycin levels determined by reverse isotope dilution method. [14C]-fosmidomycin was rapidly distributed in the tissues of rats, and was maintained in high concentration in the liver, kidneys, and bone. The serum level data after i.v. administration closely fitted a 3-compartment open model with first order kinetics after nonlinear least squares regression by NONLIN. The half-lives of the serum level curves for the early, midway, and terminal phases were: 0.13, 0.51, and 17.3 h, respectively in rats; and 0.44, 0.75, and 2.0 h, respectively in dogs.

Quantitative histological findings in the sural nerves of neonates

The quantitative histological study was achieved on the sural nerves obtained at autopsy from three neonates without neurological disorders. The distributions of the myelinated fiber diameters were unimodal and the peaks of the size frequency distributions were at 2-3 microns. These findings coincide with those for children under two years of age, and the latter dose with those for children over 2 months old and adults reported up to now. There were many smaller myelinated fibers under 4 microns in the neonates in comparison with in the children over 2 years old or adults. The densities were higher than those for children over 2 months old, and the ratio of unmyelinated to myelinated fibers was approximately twice as large as that in the children over 2 years old.

Two-site immunoenzymometric assay for thyrotropin in dried blood samples on filter paper

We describe a sensitive, simple, and rapid two-site immunoenzymometric assay for thyrotropin in dried blood samples on filter paper, for use in screening for neonatal primary hypothyroidism. In this method, two dried-blood spots of 3 mm diameter (equivalent to about 5.4 microliter of blood) are incubated overnight with anti-thyrotropin-beta-D-galactosidase complex in an anti-thyrotropin coated tube. Then the enzyme activity in the washed tube is determined fluorophotometrically. The range of thyrotropin measurable is 10 to 160 milli-int. units/L blood. Values for thyrotropin in dried blood samples determined by this method and those determined by radioimmunoassay correlated highly (r = 0.96).

Two-site immunoenzymometric assay for thyrotropin in dried blood samples on filter paper

We describe a sensitive, simple, and rapid two-site immunoenzymometric assay for thyrotropin in dried blood samples on filter paper, for use in screening for neonatal primary hypothyroidism. In this method, two dried-blood spots of 3 mm diameter (equivalent to about 5.4 microliter of blood) are incubated overnight with anti-thyrotropin-beta-D-galactosidase complex in an anti-thyrotropin coated tube. Then the enzyme activity in the washed tube is determined fluorophotometrically. The range of thyrotropin measurable is 10 to 160 milli-int. units/L blood. Values for thyrotropin in dried blood samples determined by this method and those determined by radioimmunoassay correlated highly (r = 0.96).

Enzyme immunoassay of thyroxine in serum and dried blood samples on filter paper

A double antibody heterologous enzyme immunoassay was developed for measuring thyroxine (T4) in serum and in dried blood samples on filter paper for use in screening for neonatal hypothyroidism. In this method, ethanol extracts of 100 microliter of serum or dried blood spots of 9 mm in diameter were incubated with T4-alkaline phosphatase conjugate prepared with glutaraldehyde, and antiserum to T4-bovine serum albumin conjugate prepared with carbodiimide. The enzyme activity in the precipitates formed with second antibody was then determined photometrically at 500 nm. The measurable range of T4 was 1-32 micrograms/dl. A linear relation was obtained between the sample volume and the T4 value, and a high correlation was found between values for T4 determined by this method and those for T4 in serum determined by radioimmunoassay (coefficient of correlation: r=0.97 for serum and r=0.88 for dried blood samples).

Measuring thyroxine and thyrotropin simultaneously in a dried blood sample on filter paper, to screen for neonatal hypothyroidism

We have developed a highly sensitive radioimmunoassay of thyroxine and thyrotropin for mass screening for neonatal hypothyroidism. This assay involves a single disc (3 mm diameter) of dried blood on filter paper. The minimum detectable concentrations are 15 pg/tube (10 microgram/L) for thyroxine and 15 nano-int. units/tube (10 milli-int. units/L) for thyrotropin; intra- and interassay CV's are less than 15% in both assays. The high sensitivity of this method is due to use of labeled thyroxine with high specific activity (3 kCi/g) and of an anti-thyrotropin serum with high affinity (Keq = 7.8 x 10(11) L/mol). With this method, 11337 newborns were screened; a follow-up study revealed that only newborns with both high thyrotropin and low thyroxine concentrations had permanent hypothyroidism. We conclude that this method is sensitive, simple, and reliable and that the recall rate with this method is much lower than that of tests for measuring thyroxine or thyrotropin alone.

Measuring thyroxine and thyrotropin simultaneously in a dried blood sample on filter paper, to screen for neonatal hypothyroidism

We have developed a highly sensitive radioimmunoassay of thyroxine and thyrotropin for mass screening for neonatal hypothyroidism. This assay involves a single disc (3 mm diameter) of dried blood on filter paper. The minimum detectable concentrations are 15 pg/tube (10 microgram/L) for thyroxine and 15 nano-int. units/tube (10 milli-int. units/L) for thyrotropin; intra- and interassay CV’s are < 15% in both assays. The high sensitivity of this method is due to use of labeled thyroxine with high specific activity (3 kCi/g) and of an anti-thyrotropin serum with high affinity (Keq = 7.8 × 10(11) L/mol). With this method, 11337 newborns were screened; a follow-up study revealed that only newborns with both high thyrotropin and low thyroxine concentrations had permanent hypothyroidism. We conclude that this method is sensitive, simple, and reliable and that the recall rate with this method is much lower than that of tests for measuring thyroxine or thyrotropin alone.

Experimental anemia induced by excess iron excretion

The effect of desferrioxamine on several hematological parameters was studied in growing rats. Animals given desferrioxamine intramuscularly (150 mg/kg daily) had increased urinary iron after one week, and decreased hemoglobin after 2 weeks. The difference in hemoglobin concentration between the treated and control groups was significant after 4 weeks of treatment with desferrioxamine, but the difference in the numbers of erythrocytes was not significant. The anemia was of hypochromic type. Desferrioxamine at this dosage did not retard growth. These findings support our previously reported concept of "iron-losing anemia".

An enzyme-immunoassay for estriol

A practical method was developed for enzyme-immunoassay of serum estriol, with alkaline-phosphatase as a marker enzyme. Alkaline-phosphatase was conjugated with estriol-6-(O-carboxymethyl) oxime using water soluble carbodiimide. The estriol-alkaline-phosphatase complex, which has both enzyme activity and capacity to bind anti-estriol serum, was obtained by Sephadex G-200 gel filtration. This complex, which was stable for at least 3 months at 4 degrees C, was used as enzyme-labelled estriol. Anti-estriol serum raised against estriol-6-(O-carboxymethyl) oxime bovine serum albumin was employed. "Bound and free" estriol were separated by the double antibody method. A linear relation was obtained between estriol concentration and antibody-bound alkaline-phosphatase activity in the range of 0.2-100 ng estriol/ml. In this assay system, cross-reactivity with other steroids was negligible under physiological conditions, and endogenous alkaline-phosphatase, which increases during the late pregnancy, caused no interference. The coefficients of variation were 3.3-14.2% (within assays), and less than 22% (between assays), and the mean recovery rate was 77.5%. Serum estriol values determined by the present method correlated well with those determined by radioimmunoassay (r=0.90 for total estriol; r=0.98 for free estriol). The present method of enzyme-immunoassay is suitable for measurement of serum estriol during pregnancy.

Adenosine triphosphate content in Lactobacillus casei and the blender-resistant phage-cell complex-forming ability of cells on infection with PL-1 phage

The intracellular ATP content of Lactobacillus casei ATCC 27092 grown in a glucose-containing medium was almost constant (2 to 3 microgram/mg dry wt. cells) through the early to middle stage of logarithmic phase, but it was lowered to less than 0.1 microgram/mg after cessation of growth owing to the exhaustion of available glucose. All the cells in the early stage of stationary phase were still viable and thus considered to be in a starved state. When such starved cells were infected with PL-1 phages in a tris-maleate buffer of pH 6.0, the process of forming blender-resistant phage-cell complexes signifying the complete injection of phage genomes into the cells was much inhibited. There was a good correlation between the ATP content of cells and the extent of the formation of blender-resistant phage-cell complexes and the correlation coefficient between them was 0.89 + 0.09 at the 95% confidence limit. On the other hand, the process of forming both the phage-adsorbed cells and the anti-phage serum-resistant phage-cell complexes were not affected by the ATP content of cells. Feeding of glucose to such starved cell cultures caused the cells to restore both the ATP content and the ability to form blender-resistant phage-cell complexes. Such restoration was also observed when the starved cells collected by centrifugation were incubated in a glucose-containing medium. The significance of the intracellular level of high energy compounds such as ATP for the mechanism of the injection of phage genomes into the cells is discussed.