Cellular catabolism of normal very low density lipoproteins via the low density lipoprotein receptor-related protein/alpha 2-macroglobulin receptor is induced by the C-terminal domain of lipoprotein lipase

Lipoprotein lipase (LPL) binds to the low density lipoprotein receptor-related protein (LRP)/alpha 2-macroglobulin receptor and induces catabolism of normal human very low density lipoproteins (VLDL) via LRP in vitro. Recent studies showed that the C-terminal domain of LPL can bind LRP in solid phase assays and inhibit cellular catabolism of two LRP ligands, activated alpha 2-macroglobulin and the 39-kDa receptor-associated protein (Williams, S.E., Inoue, I., Tran, H., Fry, G. L., Pladet, M.W., Iverius, P.-H., Lalouel, J.-M., Chappell, D.A., and Strickland, D.K. (1994) J. Biol. Chem. 269, 8653-8658). The current study investigated the potential for this region of LPL to promote cellular catabolism of VLDL via LRP. A fragment comprising the C-terminal domain of LPL (designated LPLC) was expressed in bacteria and found to promote cellular binding, uptake, and degradation of normal human VLDL in a dose-dependent manner. These effects were present whether LPLC was added simultaneously with 125I-VLDL or was prebound to cell surfaces prior to the assay. Mutations involving Lys407, Trp393, Trp394, or deletion of the C-terminal 14 residues reduced the effects of LPLC. Three LRP-binding proteins, the receptor-associated protein, lactoferrin, and a polyclonal antibody against LRP, competed for 125I-VLDL degradation induced by LPLC. Heparin or heparinase treatment of cells prevented LPLC-induced 125I-VLDL catabolism. Thus, cell-surface proteoglycans play an important role in this pathway. Interestingly, either LPLC or LPL when added in excess could block LPL-induced 125I-VLDL degradation presumably by interacting directly with LRP. However, unlabeled VLDL could not prevent catabolism of 125I-labeled LPLC or LPL. These data show that cellular fates for VLDL versus LPLC or LPL are divergent. This is probably due to independent catabolism of the latter via cell-surface proteoglycans. In summary, these in vitro studies indicate that a fragment of LPL corresponding to the C-terminal domain mimics the native enzyme with respect to induction of VLDL catabolism via LRP. Because LPLC lacks the catalytic site of native LPL, these studies establish that lipase activity is not required for LRP-mediated lipoprotein catabolism.

[Cytofluorometric DNA analysis in different histological patterns of thyroid papillary carcinoma]

Some papillary carcinomas of thyroid glands contain not only typical papillary structures but also various histological features in the same tumor. To investigate how areas with variable histological features differ in proliferative activity and how these differences influence the biological behavior of the whole tumor, we measured DNA contents by cytofluorometry in six papillary carcinomas with different histological features in the same tumor. DNA ploidy patterns were determined and the percentage of S plus G2M phase cells (S + G2M fraction) was calculated only in diploid tumors to assess the proliferative activity. The following conclusions were drawn. 1) It was demonstrated that there were differences in proliferative activity among areas with variable histological features in 4 of six tumors. 2) In the tumors which invaded adjacent tissues, the proliferative activity of the invasive area tended to be higher than that of the original area of the tumor. Therefore, the possibility exists that more precise evaluation of the biological behavior of the tumor can be obtained by measuring DNA contents of the tumor cells in invasive areas. 3) There was the gap in S + G2M fractions among some tumors with the same histological differentiation. Accordingly, DNA analysis of tumors would be of value in estimating proliferative activity.

Role of adenosine in dialysis-induced hypotension

First, this investigation showed that plasma levels of inosine, hypoxanthine, and xanthine, which are metabolites of adenosine, rose sharply when blood pressure dropped suddenly along with symptoms during a hemodialysis session (sudden hypotension), but not when it decreased gradually with eventual symptoms (gradual hypotension). Because adenosine has an action to dilate vessels, this result indicates the possibility that the increased release of adenosine would be a cause of sudden hypotension. Second, it was found that the frequency of sudden hypotension decreases with the administration of caffeine, which is an adenosine-receptor antagonist, whereas the frequency of gradual hypotension did not change. This result supports the above-mentioned hypothesis that adenosine may well be a mediator of sudden hypotension, but not of gradual hypotension. Third, our investigation demonstrated no significant differences in plasma norepinephrine level, in plasma renin activity, or in mean blood pressure between the hemodialysis session in which caffeine was administered and the session in which a placebo was given. These findings suggest that the effect of caffeine administration to prevent sudden hypotension is not mediated by the stimulation of the sympathetic nervous system or activation of the renin-angiotensin system, but by the adenosine-receptor antagonism.

Histopathology of the lungs of rabbits experimentally infected with Dirofilaria immitis

The lungs of rabbits experimentally infected with Dirofilaria immitis were examined histopathologically, to compare the changes with those seen in human pulmonary dirofilariasis. Eight rabbits were infected subcutaneously with two to eight immature worms to induce pulmonary dirofilariasis. Obstructive changes, similar to those reported in human pulmonary dirofilariasis, were observed in the blood vessels surrounding the worms. A form of arteritis, similar to occlusive arteritis, and periarteritis were also observed in the lungs of the rabbits. These results suggest that experimentally induced dirofilariasis in the rabbit is a useful animal model for human pulmonary dirofilariasis.

The carboxyl-terminal domain of lipoprotein lipase binds to the low density lipoprotein receptor-related protein/alpha 2-macroglobulin receptor (LRP) and mediates binding of normal very low density lipoproteins to LRP

Lipoprotein lipase (LPL) binds with high affinity to the low density lipoprotein receptor-related protein/alpha 2-macroglobulin receptor (LRP) and promotes binding, uptake, and degradation of normal triglyceride-rich lipoproteins in a process mediated by LRP (Chappell, D. A., Fry, G. L., Naknitx, M.A., Muhonen, L. E., Pladet, M. W., Iverius, P-H., and Strickland, D. K. (1993) J. Biol. Chem. 268, 14168-14175). To localize the portion of LPL that is responsible for interacting with LRP, fragments of LPL were expressed in bacteria. A fragment of human LPL containing the COOH-terminal domain (residues 313-448, designated LPLC) which lacks the catalytic site was able to bind to LRP. Purified LRP bound specifically to microtiter wells coated with LPL or LPLC with KD values of 2.8 and 5 nM, respectively. The effects of several mutations of LPLC were tested. Mutation of Lys407 to Ala reduced the affinity of LPLC for LRP by approximately 10-fold. Like native LPL, LPLC prevented the binding of activated alpha 2-macroglobulin and the 39-kDa receptor-associated protein to LRP and inhibited the internalization and degradation of activated alpha 2-macroglobulin and receptor-associated protein in cultured fibroblasts. LPLC also bound to 125I-labeled human normal triglyceride-rich lipoproteins and promoted their binding to purified LRP and to cultured cells. Mutation of Trp393 and Trp394 to Ala completely abolished the ability of LPLC to bind to lipoproteins, but had little effect on its interaction with LRP. These data indicate that the COOH-terminal domain of LPL may function both in binding lipoproteins and mediating their interaction with LRP.

Charge movement and Ca2+ release in normal and dysgenic foetal myotubes

Intramembrane charge movement and Ca2+ release from sarcoplasmic reticulum was studied in foetal skeletal muscle cells from normal and mutant mice with 'muscular dysgenesis' (mdg/mdg). It was shown that: 1) unlike normal myotubes, in dysgenic myotubes membrane depolarization did not evoke calcium release from the sarcoplasmic reticulum; 2) when all ionic currents are pharmacologically suppressed, membrane depolarization produced an asymmetric intramembrane charge movement in both normal and dysgenic myotubes. The relationship between the membrane potential and the amount of charge movement in these muscles could be expressed by a two-state Boltzmann equation; 3) the maximum amount of charge movement associated with depolarization (Qon max) in normal and in dysgenic myotubes was 6.3 +/- 1.4 nC/microF (n = 6) and 1.7 +/- 0.3 nC/microF (n = 6) respectively; 4) nifedipine (1-20 microM) applied to the bath reduced Qon max by about 40% in normal muscle cells. In contrast, the drug had no significant effect on the charge movement of dysgenic myotubes; and 5) the amount of nifedipine-resistant charge movement in normal and in dysgenic myotubes was 3.5 nC/microF (n = 3) and 1.7 nC/microF 1 maximum (n = 3), respectively.

Japanese family with Creutzfeldt-Jakob disease with codon 200 point mutation of the prion protein gene

We report the first Japanese case of familial Creutzfeldt-Jakob disease (CJD) with the heterozygous point mutation at codon 200 of the prion protein gene. This suggests that the mutation is not race-specific. The clinical and pathologic features of this case are not different from those of sporadic CJD without point mutations. Some healthy members of the family also carry the same mutation in the autosomal dominant inheritance expression.

Regulation of a non-selective cation channel of cultured porcine coronary artery smooth muscle cells by tyrosine kinase

A non-selective cation channel was found in primary cultured porcine coronary artery smooth muscle cells. In patch-clamp studies in the cell-attached mode, this channel was activated by bath application of genistein, a specific inhibitor of tyrosine kinase, but not by daidzein, which is similar in structure to genistein but has no inhibitory effect on tyrosine kinase. This channel discriminated poorly between Na+ and K+ (permeability ratio PNa/PK = 1.03), and also transported Ca2+. The single-channel conductance measured with a pipette solution containing 150 mM Na+ was 139 +/- 24 pS (mean +/- SD, n = 5), and that for the inward current measured with 100 mM Ca2+ solution was 25 +/- 9 pS (n = 3). This non-selective cation channel was also activated by staurosporine, a non-specific protein kinase inhibitor, but not by H-7, an inhibitor of protein serine/threonine kinase. These results suggest that the activity of the non-selective cation channel is negatively regulated by tyrosine kinase activity, and thus a decrease of the enzyme activity in porcine coronary artery smooth muscle cells may result in membrane depolarization and Ca2+ entry.

Chemoprevention of tongue carcinogenesis in rats

The inhibitory effects of vitamin A, selenium, butylated hydroxytoluene, and their combinations on tongue carcinogenesis induced by 4-nitroquinoline 1-oxide were examined in Sprague-Dawley rats. After 4 months of administration of 4-nitroquinoline 1-oxide, a wide range of lesions from hyperplasia to early invasive carcinoma was seen. The lesions were fewer and the carcinomas were less advanced in the rats given preventive treatment. The chemopreventive effect of vitamin A plus butylated hydroxytoluene was most effective. After 7 months of 4-nitroquinoline 1-oxide administration, the incidence, the macroscopic diameter, and the microscopic depth of invasion among carcinomas were smaller in the chemopreventive groups than in the nonchemopreventive group. We conclude that vitamin A, selenium, and butylated hydroxytoluene inhibit tongue carcinogenesis induced by 4-nitroquinoline 1-oxide in rats. The inhibitory effect of combined chemopreventives is not always superior to that of each chemopreventive agent used alone.

Copper disposition of the fetus and placenta in a patient with untreated Wilson's disease

A patient with untreated Wilson's disease showed the possibility of fetal liver damage and copper accumulation in the placenta by this disease. This is the first report of copper disposition on the fetus and placenta in a patient with untreated Wilson's disease.

Estimation of proliferative activity of experimental tongue carcinoma in rats. Immunohistochemical and DNA cytofluorometric analysis

Precancerous lesions and carcinomas were produced in rat tongues by oral administration of 0.001% 4-nitroquinoline 1-oxide (4NQO) in drinking water, and the biological characteristics and tumor kinetics were studied. Bromodeoxyuridine labeling index (BrdU L.I.) was determined immunohistochemically, and the nuclear DNA content was measured by DNA cytofluorometry. The BrdU L.I. was lowest in normal epithelium (3.49 +/- 0.49%), higher in papillomas (8.24 +/- 1.76%) and highest in squamous cell carcinomas (13.36 +/- 4.40%). Normal lingual epithelial cells, papillomas and 18 of the 25 squamous cell carcinomas showed a diploid pattern, while 7 squamous cell carcinomas showed a diploid plus tetraploid pattern. The correlation between polyploidization and tumor progression was significant, but the correlation between BrdU L.I. and tumor progression was not significant. The results suggest that while polyploidization of tumors increases with tumor progression the growth rate of tumors does not necessarily do so.

Hospice care in Japan

Hospice care was introduced in Japan in the 1970s. There are currently an estimated 21 programs, which are primarily hospital-based. This paper provides an overview of the history, current state, and future trends of hospice care in Japan. Four programs are described, including staffing information, length of stay, and prognoses of patients. Hospice care in Japan is compared to hospice care in the United States and major differences are described. Lastly, the concept of "truth telling" is explored within the context of the Japanese culture. The discussion is based on a review of the literature and a mailed survey completed by 16 Japanese hospice programs during July 1992. The paper is in four sections: An overview of Japan. The history, current state, and future trends of hospice care in Japan. The major differences between hospice care in Japan and the United States. An exploration of "truth telling" within the context of the Japanese culture.

Binding of lipoprotein lipase to heparin. Identification of five critical residues in two distinct segments of the amino-terminal domain

Binding to heparan sulfate governs many aspects of the physiological action and regulation of the lipolytic enzyme, lipoprotein lipase (LPL). In an attempt to identify the structural determinants which mediate this interaction, basic residues in three segments of the primary sequence of human LPL (residues 147-151, 279-282, and 292-304) were replaced with alanine, either singly or in various combinations, and variant proteins were subjected to affinity chromatography on heparin-Superose. Five basic residues in two distinct segments of the primary sequence were critical determinants of the high affinity for heparin manifested by the active enzyme (R279, K280, R282, K296, R297). By contrast, no such evidence could be detected for basic residues in the first cluster (K147, K148) or for other basic residues in the third cluster (K292, R294, K304), while the evidence for K300 was unresolved. The conformation of this heparin-binding domain can be inferred by reference to the three-dimensional structure of the homologous enzyme, pancreatic lipase (Winkler, F. K., D'Arcy, A., and Hunziker, W. (1990) Nature 343, 771-774). Affinity of the active enzyme for heparin could not be reduced below a threshold, suggesting that other heparin-binding determinants exist elsewhere in the molecule, as supported by recently published evidence (Davis, R. C., Wong, H., Nikazy, J., Wang, K., Han, Q., and Schotz, M. C. (1992) J. Biol. Chem. 267, 21499-21504).

A new wearable system for continuous monitoring of arteriovenous fistulae

A wearable system to constantly monitor the bruit generated by an AV fistula at times other than during dialysis was developed, and provided early detection of rapidly developing thrombi that cause occlusion of the fistular vessels. The system consists of a downsized microphone that continuously monitors the bruit generated, a warning device worn like a wristwatch, and a wire running down from the microphone to the emergency warning device. The microphone converts the bruit into an electrical signal and outputs it to the warning device. The emergency warning is then sounded whenever the input signal from the tiny microphone is weaker than a preset level. The warning device was set off in 4 of 21 long-term dialysis patients with arteriovenous fistulas, and within several hours all 4 developed an occlusion. One of the 14 patients with a graft had the device go off while sleeping, but it was a false alarm due to positioning that resulted in compression of the fistula arm.

Inhibitory effect of FUT-175 on complement activation and its application for glomerulonephritis with hypocomplementemia

FUT-175 (6-amidino-2-naphthyl p-guanidinobenzoate dimethane-sulphonate), a potent serine protease inhibitor, has been reported to inhibit complement activity in vitro, and especially the classical complement pathway effectively. In the present study, we examined the inhibitory effect of FUT-175 on the classical complement pathway components by hemolytic assay using purified human complement components. As a result, 50% inhibition of the C1 protease activity for classical C3 convertase formation and for C2 was obtained with 3.0 x 10(-8) M and 7.0 x 10(-8) M of FUT-175, respectively. FUT-175 did not inhibit the C2 protease activity at all. We then administered FUT-175 to 5 glomerulonephritic patients with hypocomplementemia and proteinuria in order to assess the clinical effectiveness of this drug. When FUT-175 was administered intravenously and continuously at a rate of 0.1 to 0.2 mg/kg/hr for 2 weeks, the urinary protein excretion decreased significantly from 2.9 +/- 0.8 to 1.4 +/- 0.5 g/day (P < 0.025). In these patients, some of the serum complement markers (serum C3, C4 level and the hemolytic activity via the classical complement pathway (CH50)) were increased after FUT-175 administration. The above findings suggests that FUT-175 can exert beneficial effects on glomerulonephritis with hypocomplementemia by inhibiting complement activation.

Mechanism of activation of the Ca(2+)-activated K+ channel by cyclic AMP in cultured porcine coronary artery smooth muscle cells

Activation of the Ca(2+)-activated K+ channel (KCa-channel) by adenosine 3', 5'-cyclic monophosphate (cAMP) and cAMP-dependent protein kinase (A-kinase) in cultured smooth muscle cells from porcine coronary artery was investigated using the patch-clamp technique. In cell-attached patches, the KCa-channel was activated when forskolin (10 microM) was applied to the bath. In excised inside-out patches, application of 50 microM cAMP to the bath activated the KCa-channel in the presence of A-kinase (10 units/ml) and ATP (1 mM). In addition, the KCa-channel was activated directly by application of cAMP to the cytoplasmic side of the membrane in the absence of A-kinase. The activation by cAMP or by A-kinase required intracellular Ca2+, and was enhanced by increase of intracellular Ca2+. At a low concentration (3 x 10(-7) M) of Ca2+, more than 2 mM cAMP was required for activation of the KCa-channel, but with 10(-6) M Ca2+, 100 microM cAMP was sufficient for activation. These results suggest that there are two mechanisms of activation of the KCa-channel by cAMP: direct activation, and indirect activation via phosphorylation of the channel by A-kinase.

Can high blood pressure alone increase erythrocytic intracellular sodium concentration?

In order to clarify the direct effects of high blood pressure on erythrocytic intracellular sodium concentration ([Na+]i) and sodium transport systems, a static pressure of 2.5 atm was applied to whole blood in plastic syringes at room temperature for 5 and 24 h. In the control samples, 5 h incubation under atmospheric pressure produced a significant decrease in ouabain-sensitive Na(+)-K+ pump activity and plasma pH, but no change in other parameters. After 24 h incubation, [Na+]i and mean corpuscular volume were significantly increased and intracellular potassium concentration, ouabain-sensitive Na(+)-K+ pump activity, and plasma pH were decreased. The change in [Na+]i during incubation under atmospheric pressure may be due to the increased permeability of the cell membrane and the decrease in ouabain-sensitive Na(+)-K+ pump activity. The pressure load did not increase erythrocytic [Na+]i but did decrease it relative to the control. The pressure load had no apparent effects on sodium transport systems, mean corpuscular volume and pH of plasma relative to the control. Although the mechanisms of the effect of pressure load on [Na+]i were not determined, we did find that high blood pressure alone was unable to increase erythrocytic [Na+]i.

Intramembrane charge movement in developing skeletal muscle cells from fetal mice

The development of intramembrane charge movement was studied in freshly isolated skeletal muscle cells from 13- to 19-day-old mouse fetuses. Charge movement was present in myotubes from 13-day-old fetuses. The relationship between charge movement and membrane potential could be described by a two-state Boltzmann equation. The amount of maximum charge movement (Qmax) increased substantially with the age of the fetuses from 2.84 +/- 0.39 nC/microF (n = 10) at day 13 to 10.01 +/- 0.97 nC/microF (n = 15) at day 19. Nifedipine (1 microM) consistently reduced Qmax by 33 +/- 2% (n = 37) of the control value at each age studied. Increasing the concentration of nifedipine to 20 microM had no further effect, suggesting that the charge movement in developing myotubes consists of at least two components: a nifedipine-sensitive charge movement (Qns) and a nifedipine-resistant one (Qnr). Both Qns and Qnr increased exponentially with a distinct enhancement of rate at day 16.

Vasopressin modulates K(+)-channel activities of cultured smooth muscle cells from porcine coronary artery

The ATP-sensitive K+ channel (KATP channel) and the Ca(2+)-activated K+ channel (KCa channel) were active in cell-attached and excised inside-out patch configurations in cultured smooth muscle cells of the porcine coronary artery. Vasopressin activated the KCa channel (240 pS) when it was applied in the bath in the cell-attached patch mode presumably because of an increase in intracellular Ca2+, but it had no direct effect on the KCa channel. However, vasopressin directly blocked the KATP channel from outside the cell membranes in a concentration-dependent manner in both outside-out and cell-attached patch configurations; the K(+)-channel opener, nicorandil, reversed this effect. The KATP channel (30 pS) was highly active in the intact cell-attached patch configuration when the pipette contained a physiological concentration of Ca2+, suggesting that this channel may control the resting membrane potential. (The block might produce depolarization of the cells and might result in the contraction of smooth muscle cells.) These observations suggest that the KATP channel may play a role, at least in part, in controlling the contraction of smooth muscle cells of the coronary artery and that the control of vascular tone by vasopressin may be related to its ability to block the KATP channel.

Analysis of IgA antibody to Pseudomonas aeruginosa in sera and sputa of patients with chronic airway diseases

The change of IgA system for Pseudomonas infection was examined by enzyme-linked immunosorbent assay of the system in sera and sputa of patients with chronic airway diseases. The anti-Pseudomonas total IgA antibody titers in both sera and sputa were not elevated in group I with no infection (mainly chronic bronchitis) and group II infected with bacteria other than Pseudomonas, but were elevated in group III colonized transiently with Pseudomonas [diffuse panbronchiolitis (DPB) and bronchiectasis] and group IV colonized persistently with Pseudomonas (mainly DPB). The elevation in the sera and sputa were mainly due to monomeric IgA and polymeric IgA (S-IgA), respectively, and values were significantly higher in group III than in group IV only in the sera. These results indicate that the IgA system is enhanced in advanced DPB and bronchiectasis complicated by Pseudomonas infection, and that the anti-Pseudomonas IgA antibody titer in serum is more useful than that in sputum for the diagnosis of respiratory Pseudomonas infection.