In-vitro evidence for carrier-mediated uptake of acidic drugs by isolated bovine brain capillaries

[3H]Acetic acid was taken up into the isolated brain capillaries in a temperature and concentration dependent manner. The initial uptake rates were pH dependent over the range 5.0-7.4. An increase of the uptake rate with decrease in medium pH was not seen in the presence of unlabelled acetic acid (10 mM). The uptake of [3H]acetic acid was significantly reduced in the presence of several drugs having a monocarboxylic group. The initial uptake of [14C]salicylic acid was also pH dependent and was inhibited by acetic acid and acidic drugs. A mutually competitive inhibition was observed for the uptake of acetic acid and salicylic acid. The present study demonstrates that acidic drugs having a monocarboxylic group are transported by a common carrier-mediated system into the brain capillaries.

Normal age-related patterns of cellular and fatty bone marrow distribution in the axial skeleton: MR imaging study

Knowledge of age-related distribution patterns of cellular and fatty marrow is critical to the interpretation of magnetic resonance (MR) imaging studies. To determine such patterns, the authors retrospectively evaluated 70 examinations each of the skull, cervical spine, thoracic spine, lumbar spine, pelvis, and proximal femur (420 examinations) in patients without known bone marrow abnormality who ranged in age from 6 months to older than 70 years. Two to four distinct patterns were identified in each anatomic area on spin-echo images obtained with a short repetition time and a short echo time. The relative frequency of the patterns for different age groups is consistent with the known physiologic conversion from cellular to fatty marrow with advancing age. Knowledge of these patterns should help in the interpretation of MR images of the axial skeleton.

In vivo and in vitro evidence for a common carrier mediated transport of choline and basic drugs through the blood-brain barrier

The blood-brain barrier (BBB) transport system for choline and basic drugs was characterized by the in vivo carotid artery injection technique (Oldendorf, Brain Res., 24, 372-376, 1970) and in vitro uptake into isolated bovine brain capillaries (Pardridge et al., J. Neurochem., 44, 1178-1184, 1985). Basic drugs such as eperisone, thiamine and scopolamine significantly inhibited choline uptake by the BBB with the half inhibitory concentration, IC50 value of 1.45, 2.06, and 0.47 mM, respectively. On the contrary, the uptake of choline was not inhibited by amino acids (L-phenylalanine and L-arginine) and acidic drugs (nicotinic acid, salicylic acid and valproic acid). Choline was taken up by the isolated brain capillaries in concentration and temperature dependent manners. The uptake of choline by the isolated bovine brain capillaries was significantly inhibited by eperisone, scopolamine and thiamine in consistent with the in vivo results. Furthermore, eperisone inhibited competitively the uptake of choline with the inhibition constant, Ki value of 455 microM. According to these results it was suggested that in the BBB choline and basic drugs would share a common carrier-mediated transport system.

Effects of expression of mammalian G alpha and hybrid mammalian-yeast G alpha proteins on the yeast pheromone response signal transduction pathway

Scg1, the product of the Saccharomyces cerevisiae SCG1 (also called GPA1) gene, is homologous to the alpha subunits of G proteins involved in signal transduction in mammalian cells. Scg1 negatively controls the pheromone response pathway in haploid cells. Either pheromonal activation or an scg1 null mutation relieves the negative control and leads to an arrest of cell growth in the G1 phase of the cell cycle. Expression of rat G alpha s was previously shown to complement the growth defect of scg1 null mutants while not allowing mating. We have extended this analysis to examine the effects of the short form of G alpha s (which lacks 15 amino acids present in the long form), G alpha i2, G alpha o, and Scg1-mammalian G alpha hybrids. In addition, we have found that constructs able to complement scg1 are also able to inhibit the response to pheromone and mating when expressed in a wild-type SCG1 strain. Overexpression of Scg1 has a similar inhibitory effect. These results are consistent with a model proposed for the action of Scg1 as the alpha component of a heterotrimeric G protein in which the beta gamma component (Ste4/Ste18) activates the pheromone response after dissociation from Scg1. They suggest that the G alpha constructs able to complement scg1 can interact with beta gamma to prevent activation of the pathway but are unable to interact with pheromone receptors to activate the pathway.

Application of HPLC in disposition study of A14-125I-labeled insulin in mice

To describe quantitatively the in vivo distribution and elimination of insulin, high-performance liquid chromatography (HPLC) separation was applied to the pharmacokinetic study of human insulin labeled with 125I at tyrosine A14 (A14-125I-insulin) as a tracer. Intact A14-125I-insulin levels were determined by HPLC and trichloroacetic acid (TCA) precipitation in plasma and various tissues after its intravenous bolus injection into mice. TCA precipitation consistently overestimated the intactness of A14-125I-insulin compared with HPLC, possibly due to the presence of both a TCA-precipitable intermediate degradation product of labeled insulin found in HPLC elution profiles and reported high-molecular-weight forms of labeled insulin in plasma. Thus, TCA precipitation gave a considerably lower total plasma clearance (Cltot) value than HPLC. The half-life of A14-125I-insulin was prolonged by a simultaneous injection of 8 U/kg unlabeled insulin, and labeled insulin behaved similarly to [14C]inulin (an extracellular fluid marker). The concentration time profiles of HPLC-separated labeled insulin in plasma were analyzed by a noncompartmental moment method, and both Cltot and steady-state apparent volume distribution (VDss) of A14-125I-insulin were considerably decreased by unlabeled insulin coadministration. In particular, VDss of labeled insulin decreased by 79%, similar to that of inulin (181 ml/kg), suggesting that the nonspecific binding of labeled insulin to tissues was so small that VDss of labeled insulin was reduced to the extracellular fluid volume (approximately 20% of the body weight) when its receptor binding was blocked effectively by unlabeled insulin.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidic drug transport in vivo through the blood-brain barrier. A role of the transport carrier for monocarboxylic acids

The relationship of the transports between acidic drugs and monocarboxylic acids through the blood-brain barrier (BBB) was examined using the carotid artery injection technique in rats. The BBB uptakes of [3H]acetic acid and [14C]salicylic acid were significantly reduced by the presence of the respective unlabeled compounds, valproic acid, lactic acid, benzoic acid, nicotinic acid or beta-lactam antibiotics (benzylpenicillin, propicillin and cefazolin), but was not reduced by choline, phenylalanine and a basic drug, eperisone. A remarkable pH dependency was observed for the BBB uptake of [14C]salicylic acid at the pH region of 4.0 to 7.4. Interestingly, 10 mM of salicylic acid diminished significantly the pH dependent BBB uptake of [14C]salicylic acid. Similar results were obtained in the BBB uptake of [14C]nicotinic acid. No significant difference was observed in the transport of monocarboxylic acids through the BBB between normotensive Wistar KY rats (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP). From these observations, acidic drugs could be transported by a carrier-mediated system for monocarboxylic acids at the BBB and the transport system was not changed by the disease state.

Dysfunction of choline transport system through blood-brain barrier in stroke-prone spontaneously hypertensive rats

The blood-brain barrier (BBB) transport of choline was compared between stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar KY rats (WKY). The permeability surface area product (PS) of [3H]choline through the BBB in SHRSP (3.03 X 10(-3) +/- 1.09 X 10(-3) ml/min/g brain) was significantly lower than that in WKY (7.23 X 10(-3) +/- 0.97 X 10(-3) ml/min/g brain) in the presence of respective rat sera. No significant difference in the brain vascular space was indicated from the apparent uptake of [3H]sucrose between SHRSP and SKY. There was no significant difference for the Michaelis constant of choline transport between SHRSP (262 +/- 97 microM) and WKY (180 +/- 32 microM). However, the maximum velocity in SHRSP (3.41 +/- 1.19 nmol/min/g brain) was 37% lower than in WKY (5.40 +/- 0.38 nmol/min/g brain). Brain microdialysis technique was employed to collect the brain interstitial fluid in the rat hippocampus. The concentration of free choline in the brain dialysate in SHRSP was about half of that in WKY, while no significant difference was observed for the plasma concentration of free choline between SHRSP and WKY. In contrast, no significant difference was observed for the transport of D-[3H]glucose, 3-methyl-[3H]D-glucose and [3H]-phenylalanine through the BBB between SHRSP and WKY. Accordingly, the decreased choline concentration in the brain interstitial fluid ascribed to the specific dysfunction of the BBB choline transport has been demonstrated in SHRSP.

Seminal vesicle abscesses: spectrum of computed tomographic findings

The computed tomographic (CT) findings in four cases of seminal vesicle abscess are presented. The predominant infectious organism in two cases was Escherichia coli, one case was probably caused by Mycobacterium tuberculosis, and another by atypical mycobacterium. The CT findings included unilateral (three cases) or bilateral involvement (one case), seminal vesicle enlargement with hypodense areas within the gland (three cases), adjacent perivesicle inflammation (three cases), and associated bladder wall thickening (three cases). Although the diagnosis of seminal vesicle abscess is often overlooked clinically, CT may help suggest the correct diagnosis early thereby helping to initiate therapy.

Absorptive-mediated endocytosis of a dynorphin-like analgesic peptide, E-2078 into the blood-brain barrier

The binding and internalization of a novel analog of dynorphin-like analgesic basic peptide, [125I]E-2078 (CH3-[125I] Tyr-Gly-Gly-Phe-Leu-Arg-CH3Arg-D-Leu-NHC2H5), by isolated bovine brain capillaries were investigated. High-performance liquid chromatographic analysis showed that no significant metabolism of [125I] E-2078 occurred during incubation with brain capillaries for 30 min at 37 degrees C. The binding of [125I]E-2078 to brain capillaries increased with time and the steady-state cell-to-medium concentration ratio was 58.5 +/- 2.6 microliters/mg of protein. Approximately one-fourth of the [125I]E-2078 binding was resistant to acid wash, and showed significant dependence on temperature and medium osmolarity. The acid sensitive binding of [125I]E-2078, which presumably represents surface binding, was saturable and the Scatchard plot gave a maximal binding capacity Bmax = 147 +/- 29 pmol/mg of protein, and a half-saturation constant (KD) = 4.62 +/- 0.59 microM. Pretreatment of brain capillaries with phenylarsine oxide, an endocytosis inhibitor, completely suppressed the acid resistant binding of [125I]E-2078, but did not influence the surface binding of [125I]E-2078. The acid resistant binding of [125I] E-2078 was inhibited by poly-L-lysine and protamine, but not inhibited by insulin, transferrin, dynorphin (1-8), beta-neoendorphin, naloxone or poly-L-glutamate. Moreover, in vivo brain extraction of [125I]E-2078 in rats was 368 +/- 55% higher than that of [3H] sucrose and was significantly inhibited by 1 mM of unlabeled E-2078. These results demonstrate that E-2078 is internalized by brain capillaries via absorptive-mediated endocytosis, which is a polycation-sensitive pathway.

Distribution of blood groups in Korea

Eight populations in the southern part of the Korean peninsula were studied to elucidate their genetic structure and to understand the genetic relationships between them. For this purpose, several blood groups and other genetic markers were analyzed. In total, over 9,000 blood specimens were collected. About 2,000 specimens were tested for 9 blood groups. The gene frequencies were estimated as A = 0.2555, B = 0.2244, O = 0.5201, M = 0.5263, S = 0.0560, d = 0.0472, C = 0.6542, E = 0.3126, Fya = 0.9210, Jka = 0.4386, Dia = 0.0539, P1 = 0.1939, K = 0.0010, Le = 0.6866 and Se = 0.6311 in the total sample. A continuous variation was observed for the frequency of gene B.

Measurement of radiation dose distributions by nuclear magnetic resonance (NMR) imaging

A method is described for determining the spatial distribution of radiation dose in a tissue-equivalent phantom using nuclear magnetic resonance imaging. The conversion of ferrous ions to ferric by ionising radiation alters the magnetic moment and electron spin relaxation times of the metal ion. The spin relaxation times (T1 and T2) of the hydrogen nuclei in an aqueous solution of a ferrous salt are consequently reduced substantially. These changes in T1 and T2 can be measured using standard NMR techniques. The same conversion is used in conventional Fricke dosimetry, which can be used to calibrate the technique.

Studies of tissue NMR relaxation enhancement by manganese. Dose and time dependences

Manganese is a powerful paramagnetic material and potential NMR contrast agent. It drastically affects the NMR properties of solutions and tissues and is less toxic than most other transition elements. It also possesses some unusual and advantageous features; it alters T1 and T2 to different degrees, and it can bind to macromolecules to become even more effective at reducing proton relaxation times. The dose dependence of tissue relaxation rate increases has been measured in mice, and proton relaxation enhancement ratios that describe binding effects have been evaluated. These ratios imply that a tenfold reduction in manganese dose is achievable when the ion binds to intracellular components, and it is demonstrated that such binding effects can be a major factor in the efficacy of contrast enhancement. The effect of manganese on the ratio T1/T2 is dose dependent so that lower doses may be more useful for some imaging techniques. The postmortem time course of relaxation times in organs containing manganese varies between organs and with manganese content, and demonstrates that the relationship between tissue relaxation enhancement and metal content is not a simple correlation with concentration since large variations in T1 and T2 can occur even when metal and water content are fixed.

Studies of factors affecting the design of NMR contrast agents: manganese in blood as a model system

Some factors affecting the performance of paramagnetic ions as contrast agents for proton NMR imaging have been studied. It is demonstrated that the relaxation rate of an aqueous solution of the ion is not reliably predicted by its magnetic moment, but that significant relaxation enhancement may result when the ion is complexed with large molecules, which increases the dominant correlation time. This enhancement in turn can be altered by factors such as pH and competition for binding. Chelation of the paramagnetic ion, which may be implemented to lower its toxicity, can considerably reduce its efficacy by not only limiting its access to water but also by preventing the enhancement from associations and macromolecules. For manganese the ratio T1/T2 is a useful parameter which is sensitive to the degree of metal binding. These features of paramagnetic relaxation enhancement in tissue are demonstrated in a series of experiments on systems consisting of blood components and manganese.

Inhibition of prostaglandin synthase activity of sheep seminal vesicular gland by human serum haptoglobin

Serum haptoglobin was added to the reaction mixture of prostaglandin synthase (EC 1.14.99.1) and its inhibitory effect was studied [1-14C]Arachidonic acid was used as substrate and the enzyme activity was estimated by monitoring the radioactivity of the products after thin layer chromatography. With or without addition of hemoglobin to the reaction mixture, both the purified haptoglobin 1-1 and 2-2 showed inhibitory activity. In the presence of 5 microM hematin, however, inhibitory activity haptoglobin was not observed. Inhibition of prostaglandin synthesis in the system depended on the molar ratio of haptoglobin to hemoglobin in the reaction mixture. These results demonstrate that haptoglobin inhibits prostaglandin synthase by restricting available heme group for the enzyme activity through complexing with hemoglobin. However, haptoglobin did not inhibit completely the stimulatory effect of free hemoglobin. Relevant significant of this effect was discussed.

Karyological confirmation of conspicuous ZW sex chromosomes in two species of Pacific anguilloid fishes (Anguilliformes: Teleostomi)

Leukocyte and kidney cell cultures were used to examine the sex chromosomes of Japanese freshwater eels (Anguilla japonica) and conger eels (Astroconger myriaster). The conspicuous presence of ZW sex chromosomes, due to a drastic reduction in size of the W, was confirmed in both species, where the Z was the largest metacentric and the W was the smallest metacentric in a diploid karyotype of 38 chromosomes in both species. These species are the first examples of the ZW type of heteromorphism in eels.

An abnormal human IgA1 half-molecule

An IgA1 half-molecule, which is composed of a deleted alpha1 chain linked with a disulfide bond to an intact kappa chain, was detected in a patient (Cha). The molecular weights of the paraprotein and the isolated alpha1 chain were estimated to be 75 000 and 53 000, respectively. Identification of tyrosine as the C-terminal amino acid and the presence of idiotypic determinants in the abnormal alpha1 chain indicated that the molecule would have an intact N-terminal variable region and a C-terminal region. Furthermore, no cleavage of the abnormal protein into Fab and Fc by proteolytic enzyme isolated from Neisseria gonorrhoeae suggested the absence of a "hinge" region in the abnormal alpha1 chain.

Karyotype conservation and difference in DNA amount in anguilloid fishes

The two Pacific anguilloid sishes Anguilla japonica and Astroconger myriaster, belonging to the different families, appear to have identical chromosome numbers (2n = 38) and karyotypes, including one pair of conspicuous heteromorphic chromosomes in females. Cytophotometric measurements, however, indicate a considerable difference in DNA content between the two species.

Studies on the effects of steroids on DNA synthesis of human chromosomes in vitro

Tritiated thymidine and autoradiographic techniques were used to investigate the sequence and pattern of DNA replication of sex chromosomes in cultured human cells treated with progesterone and testosterone.The average frequencies of progesterone- and testosterone-induced chromatid aberration were 19 and 26% respectively, whereas that of spontaneous aberration was 2.5%. No chromosome aberrations were found in sex chromosomes of either sex. Aberrations were distributed throughout cells in both S and G2stages. The general production of aberrations increased with increases in the time between isotopic labeling and fixation. The mean duration of G2was over 3 hours in the control, over 4.5 hours in the progesterone-treated group and 4.75 hours in the testosterone group. Thus, G2time for human kidney cells treated with steroids was delayed about 1 to 2 hours.Striking asynchrony of DNA duplication in homologous X chromosomes in steroids-treated female cells was also observed at the end of the period. However, even in metaphases that incorporated thymidine-H3at 6 hours before fixation the hot-X was detectable. The Y chromosome in male cells showed a high percentage of labeling intensity with particularly heavy grains, differing from that of G group. Metaphases of female cells labelled at 6 hours before fixation in progesterone had an unlabeled, chromosome in the complement of moderately labeled cells. This unlabeled chromosome was also found in testosterone-treated cells prepared 10 hours after labeling and is presumed to be heteropycnotic X chromosome.