Novel point mutation in the uroporphyrinogen III synthase gene causes congenital erythropoietic porphyria of a Japanese family

The molecular basis of the uroporphyrinogen III synthase (UROIIIS) deficiency was investigated in a member of a Japanese family. This defect in heme biosynthesis is responsible for a rare autosomal recessive disease: congenital erythropoietic porphyria (CEP) or Günther's disease. The patient was homozygous for a novel missense mutation: a G to T transition of nucleotide 7 that predicted a valine to phenylalanine substitution at residue 3 (V3F). The parents were heterozygous for the same mutation. The loss of UROIIIS activity was verified by an in vitro assay system. The corresponding mutated protein was expressed in Escherichia coli and no residual activity was observed. Further studies are needed to determine whether the mutations of the UROIIIS gene (UROS) have a specific profile in Japan compared to European or American countries.

Construction of hairpin ribozymes with a three-way junction

Hairpin ribozymes with high cleavage activities were designed. An extra sequence was introduced at the 3'-end of the hairpin ribozyme to increase the binding to the substrate RNA, as compared to the wild-type hairpin ribozyme. A three-way junction (TWJ) was formed between the newly designed ribozyme and the substrate RNA. The complex with a solid TWJ showed less RNA cleavage activity than the wild-type hairpin ribozyme. However, the ribozyme with a TWJ with five unpaired bases or propandiol phosphate linkers had higher cleavage activity than the parent ribozyme without the TWJ. When a cis-cleavage system, in which the 5'-end of the substrate RNA was conjugated to the 3'-end of the ribozyme, was employed, the complex with the TWJ containing unpaired bases was also cleaved faster than the complex with the solid TWJ. This suggested that these differences in the cleavage activities were derived from the confirmation, and this was proven by nondenaturing gel electrophoresis. The TWJ hairpin ribozyme containing unpaired bases is able to bind strongly with substrate RNAs and to cleave them efficiently. Since the three-way ribozyme presented here is more active than the wild-type ribozyme, this type of ribozyme can serve as a more efficient tool to control RNA activities in vitro and in vivo.

Effects of various antiepileptic drugs on plasma levels of lamotrigine, a novel antiepileptic, in rats

The pharmacokinetics of lamotrigine (LTG) and effects of carbamazepine (CBZ), valproic acid (VPA) and zonisamide (ZNS) on LTG kinetics were investigated in rats. LTG plasma levels were measured by high-performance liquid chromatography (HPLC). A single oral administration of LTG at 2.5-10 mg/kg showed linear disposition kinetics. In the pharmacokinetic parameters of LTG when combined with CBZ, the maximal plasma concentration (Cmax) and the area under the plasma concentration curve (AUC0-36) values were significantly lower and the time to maximal plasma concentration (Tmax) value was significantly higher than those in LTG alone. Furthermore, the Cmax and AUC0-36 values of LTG when pretreated with CBZ for 7 days were significantly lower than those from simultaneous treatment with CBZ. The Cmax and AUC0-36 values of LTG when combined with VPA were significantly lower than those for LTG alone. There was no significant difference in the Tmax or time of elimination half-life (t1/2) values of LTG between simultaneous and pretreatment with VPA. Of the pharmacokinetic parameters of LTG with ZNS combination, the Cmax value of LTG after long-term dosings of ZNS decreased significantly, whereas no significant change in Cmax was observed after the combined single administration of LTG and ZNS. Single and chronic ZNS treatment did not significantly affect the Tmax, t1/2 and AUC0-36 values of LTG. The LTG trough level was significantly reduced by CBZ administration, reached the bottom level at 6 days after starting CBZ administration, and recovered gradually after withdrawal of CBZ. These results suggest that CBZ, VPA and ZNS causes changes in the plasma LTG level. They also suggest that in therapy combining LTG with one of these antiepileptics, especially CBZ, the LTG concentration in plasma should be monitored carefully.

Migration of hydroxyapatite onlays into the mandible and nasal bone and local bone turnover in growing rabbits

To determine the effects of local bone turnover on the migration of macroporous hydroxyapatite onlays in the nasal bone and mandibular ramus, we performed histomorphometric analyses of the underlying bone area in 41 New Zealand White rabbits from the age of 4 weeks. The hydroxyapatite implants were placed under the periosteum of the right nasal bone (a depository bone onto its periosteal surface and endosteal resorptive) and the mandibular ramus (resorptive onto its outer surface). The corresponding left sides were sham operated. Following fluorescence bone labeling, composite specimens of the hydroxyapatite block including both sides of the nasal bone and mandible were removed at 0 (n = 1), 3, 6, 9, 12, and 16 weeks postoperatively (n = 8, respectively) and processed to yield undecalcified sections. Bone-bone marrow interfaces in the entire area within 200 microns beneath the base of the hydroxyapatite and in the counter-area on the sham-operated side were measured under a light microscope. In all grafted specimens, the hydroxyapatite matrix was directly united with the underlying tissue by bone ingrowth. However, the sinking of the hydroxyapatite graft in the nasal bone was significant at 3 weeks postoperatively and gradually increased thereafter. In the mandible, the sinking became significant at 6 weeks. In the nasal bone, the bone area density beneath the graft showed a time-dependent decrease during the experimental period, but in the mandibular bone, the value was initially decreased at 3 weeks and then recovered to baseline level. In both bones, parameters of bone resorption, such as osteoclast number and osteoclast surface, were significantly increased from 3 weeks. While the parameters of bone formation, such as osteoblast surface and mineralizing surface, were significantly decreased from 3 weeks in the nasal bone, they were significantly increased in the mandible. Mineral apposition rate showed a significant decrease in both bones. Our data indicate that while the bone area density beneath the hydroxyapatite seemed to depend on bone formation, increased bone resorption would be more critical for the remodeling of underlying bony architecture in the migration of the hydroxyapatite graft.

Thyroid dysfunction in patients with amyloid goitre

OBJECTIVES

Widespread amyloid deposition in the thyroid gland causes diffuse, clinically apparent enlargement of the thyroid (amyloid goitre: AG). The aim of this study was to clarify the abnormalities of thyroid function in patients with AG.

DESIGN

Thirty patients with secondary amyloidosis were retrospectively analysed. Their thyroid status was evaluated using the results of routine thyroid function tests and measurement of thyroid autoantibodies. Thyroid needle biopsy was carried out to identify amyloid deposition in the thyroid gland.

RESULTS

Thyroid enlargement was observed in 19 (63%) of 30 patients with amyloidosis. Eleven of these 19 patients had a thyroid biopsy and/or autopsy and amyloid deposition was histologically revealed in 10 (defined as AG) of these 11 patients. Nine of 10 patients (90%) with AG had abnormalities of thyroid function, including five patients with hypothyroidism, one with hyperthyroidism, one with transient hypothyroidism, and two with low T3 syndrome. Five had thyroid autoantibodies. The patient with hyperthyroidism had positive thyroid stimulating antibody (TSAb) and high 131I thyroidal uptake, suggesting the coexistence of Graves' disease. Another patient suffered from thyroidal pain and showed transient hypothyroidism, high level of serum thyroglobulin and low thyroidal uptake of 123I, the clinical course being compatible with subacute thyroiditis.

CONCLUSIONS

The incidence of thyroid abnormalities accompanied by AG, although asymptomatic, is unexpectedly high. Thyroid function should therefore be regularly assessed during follow-up of patients with systemic amyloidosis.

Differential distribution of mRNAs encoding phosphatidylinositol transfer proteins alpha and beta in the central nervous system of the rat

The expression of the alpha and beta isoforms of phosphatidylinositol transfer protein (PI-TP alpha and PI-TP beta) in the adult rat brain was examined by in situ hybridization analysis with isoform-specific RNA probes. PI-TP alpha mRNA was detected in rather restricted regions of the brain whereas PI-TP beta mRNA was widely distributed in the brain. PI-TP alpha mRNA signals were remarkable in neocortex layers II/III and V/VI, Purkinje cell layer, deep cerebellar nuclei of the cerebellum, red nucleus and most part of brain stem. Low levels of PI-TP alpha transcript were present in CA3 of the hippocampus, ventral and dorsal thalamic nuclei, and motoneurons of spinal cord. No hybridization signals was obtained in the olfactory bulb, basal ganglia, amygdala, hypothalamus, and pituitary gland. In contrast, strong signals of PI-TP beta mRNA were detected in the dentate gyrus. The beta isoform mRNA was moderately expressed in olfactory bulb, layers II/III of the neocortex, striatum, CA1-CA4 regions of the hippocampus, medial habenula, cerebellum, amygdala, hypothalamus, spinal cord, and pituitary gland. Thalamus and brain stem contained relatively low, but significant levels of PI-TP beta transcript. The distinct distribution of PI-TP alpha and PI-TP beta mRNAs suggests different functional roles for each of the gene products in the mature nervous system.

Interferon alpha induces disorder of lipid metabolism by lowering postheparin lipases and cholesteryl ester transfer protein activities in patients with chronic hepatitis C

The effect of recombinant interferon alpha 2a (rIFN-alpha2a) on serum lipoprotein metabolism was assessed in 39 patients with chronic viral hepatitis C. rIFN-alpha2a was administered intramuscularly at a dose of 9 x 10(6) U/d for 2 weeks and then for 3 times a week over 6 months. The serum cholesterol concentration significantly decreased one week after rIFN-alpha2a administration. Approximately 67% of this decrease was attributed to the reduction of high-density lipoprotein (HDL)-cholesterol; a decrease in HDL2-cholesterol was more evident. By contrast, serum triglyceride levels, largely derived from very-low density lipoprotein (VLDL), significantly increased following rIFN-alpha2a treatment. Lipoprotein lipase (LPL) and hepatic triglyceride lipase (HTGL) activities in the postheparin plasma were reduced by 75.7% and by 79.4%, respectively, and decreases in plasma cholesteryl ester transfer protein (CETP) activity and its protein mass were also observed. However, prothrombin time was ameliorated by rIFN-alpha2a, suggesting that the decrease in LPL, HTGL, and CETP activities may not be due to a reduction in protein synthesis by the liver. Simple correlation analysis demonstrated that the changes in LPL activity before and after 2 weeks of treatment with rIFN-alpha2a showed a significant negative correlation with changes in serum triglyceride and VLDL-triglyceride and a positive correlation with changes in HDL-cholesterol and HDL2-cholesterol. These results suggest a major contribution of reduced LPL activity with regard to the lipoprotein disorders. In conclusion, rIFN-alpha2a treatment on patients with chronic hepatitis C causes marked changes in serum lipoprotein metabolism associated with decreases in LPL, HTGL, and CETP activities.

Genetic cholesteryl ester transfer protein deficiency is extremely frequent in the Omagari area of Japan. Marked hyperalphalipoproteinemia caused by CETP gene mutation is not associated with longevity

Low levels of HDL cholesterol have been clearly demonstrated to be associated with an increased incidence of coronary heart disease, strongly suggesting that HDL particles have an antiatherogenic function. However, little information has been available concerning the atherogenicity of a marked hyperalphalipoproteinemia (HALP). There is no agreement about whether plasma cholesteryl ester transfer protein (CETP) deficiency is associated with an antiatherogenic state or not, although this disorder was reported to be one of the major causes of marked HALP. In the current study, we have found a unique area (Omagari City, Akita Prefecture, Japan) where CETP deficiency caused by a G-to-A mutation at the 5' splice donor site of intron 14 in the CETP gene is extremely frequent. In Omagari City, the mutation was detected more than 20 times more frequently and the prevalence of a marked HALP with plasma HDL cholesterol > or = 2.58 mmol/L (100 mg/dL) was 5 to 10 times higher than in other areas of Japan. This discovery has made it possible to perform a large population-based study concerning the atherogenicity of a marked elevation of HDL cholesterol in a genetically more homogeneous population. There was a statistically significant U-shaped relationship between HDL cholesterol levels and the incidence of ischemic changes in electrocardiograms. In cases of HDL cholesterol < 1.81 mmol/L (70 mg/dL), the incidence increased in proportion to the levels of HDL cholesterol. The frequency of the CETP gene mutation was higher in patients with coronary heart disease than in healthy control subjects. In subjects aged > 80 years, the prevalence of both marked HALP and the intron 14 splicing defect was significantly lower than in the younger generation. The current study indicated for the first time that a marked HALP caused by CETP gene mutation may not represent a longevity syndrome, suggesting the importance of reevaluation of the clinical significance and pathophysiology of a marked HALP.

Gastric cancer associated with overexpression of parathyroid hormone-related peptide (PTHrP) and PTH/PTHrP receptor in relation to tumor progression

Parathyroid hormone-related peptide (PTHrP) is involved in cell proliferation in both neoplastic and non-neoplastic tissues. We describe an autopsy case of gastric cancer in a patient who showed serum hypercalcemia and overexpression of PTHrP and PTH/PTHrP receptor in the metastatic tumor cells. The primary gastric tumor was poorly differentiated adenocarcinoma, and multiple metastases were present in the bone, multiple visceral organs, peritoneum, and lymph nodes. PTHrP and its mRNA were detected only in the metastatic tumor cells, but not in primary gastric tumor. PTH/PTHrP receptor was also demonstrated immunohistologically in metastatic tumor cells. This case suggests that the expression of PTHrP is related to tumor progression and the poor prognosis in tumors associated with humoral hypercalcemia.

Expression of parathyroid hormone-related peptide (PTHrP) in gastric tumours

Parathyroid hormone-related peptide (PTHrP) is produced by various neoplasms. It has been suggested that it acts as a cytokine for cell proliferation and tumour progression. The purpose of this study was to evaluate PTHrP expression in gastric cancers by immunohistochemistry. PTHrP was expressed in 71 of 92 (77.2 per cent) gastric adenocarcinomas without humoral hypercalcaemia. In contrast, one case (5 per cent) out of 20 adenomas and none of the background non-neoplastic epithelium showed PTHrP immunoreactivity. In carcinomas, PTHrP immunoreactivity was higher in moderately differentiated adenocarcinomas (21/22; 95-5 per cent) and poorly differentiated adenocarcinomas (34/34; 100 per cent) than in well-differentiated adenocarcinomas (10/23; 43 per cent). Furthermore, PTHrP expression was more intense in the deeply invasive portions than in the mucosal carcinomas. High percentages of metastatic tumour cells in regional lymph nodes were immunopositive. PTHrP mRNA expression was confirmed by in situ hybridization in gastric adenocarcinomas. Reverse transcription-polymerase chain reaction (RT-PCR) studies of normal gastric mucosa and four human gastric cancer cell lines detected PTHrP transcription in NUGC-1 (poorly differentiated) and NUGC-3 (poorly differentiated) but not in normal gastric mucosa, MKN-1 (well differentiated), and KATO-III (signet ring cell). These findings suggest that overexpression of PTHrP may be involved in the malignant transformation and progression of gastric carcinomas.

Increased serum remnant lipoproteins in patients with apolipoprotein E7 (apo E Suita)

Apolipoprotein (apo) E7 was originally identified by Yamamura et al. in subjects with atherosclerotic cardiovascular diseases (J. Clin. Invest. 1984;74:1229). However, the lipoprotein abnormalities associated with apo E7 phenotype have not been elucidated. In the current study, to clarify the physiological roles of apo E7, lipoprotein abnormalities were studied in 12 apo E7 heterozygotes. A total of seven subjects were hyperlipidemic and five subjects were normolipidemic. The apo E phenotype was apo E7/3 in 11 subjects and apo E7/4 in one subject. Polymerase chain reaction revealed that all of the subjects with apo E7 phenotype had the same mutation as that of apo E(Suita) as reported previously (J. Biochem. 1989;105:249). All the hyperlipidemic subjects were over 40 years of age and two of them also had and severe coronary heart disease. Ultracentrifugal analysis revealed that the cholesterol level both in very low density lipoprotein and in intermediate density lipoprotein (IDL) was substantially higher in hyperlipidemic apo E7 heterozygotes, compared with control subjects and that the IDL cholesterol was also increased even in normolipidemic apo E7 heterozygotes. Polyacrylamide gel electrophoresis of lipoproteins showed a midband, which implies the increase of remnant lipoproteins, in 11 subjects out of 12, irrespective of the presence or absence of hyperlipoproteinemia. In two cases, a broad beta pattern was observed similar to that seen in type III hyperlipoproteinemia. Dietary therapy was dramatically effective for the treatment of hyperlipidemia in patients with apo E7. These findings confirm that apo E is crucial for remnant lipoprotein metabolism and that apo E7 is related to the increase in serum remnant lipoproteins, which leads to hyperlipoproteinemia in association with obesity, aging and impaired glucose metabolism.

Biphenotypic blast crisis of chronic myelogenous leukemia: abnormalities of p53 and retinoblastoma genes

The molecular mechanisms responsible for progression of chronic myelogenous leukemia (CML) to blast crisis have not been well defined. Blast crisis may be partially related to inactivation of tumor suppressor genes/such as p53 or retinoblastoma (Rb) gene. There is evidence for an association of blast cell phenotypes in CML with alterations of these genes: a strong association of myeloid phenotypes with abnormalities of the p53 gene and a weaker association of lymphoid phenotypes with abnormalities of the Rb system. We found a marked decrease in Rb gene product and rearrangements of the p53 gene simultaneously in two cases of biphenotypic blast crisis of CML (myeloid and B-lymphoid). These results support the association of blast cell phenotypes with alterations in tumor suppressor genes in CML blast crisis.

Cloning, expression, and characterization of a novel phospholipase D complementary DNA from rat brain

Phospholipase D (PLD) is implicated in important cellular processes such as signal transduction, membrane trafficking, and mitosis regulation. Recently, cDNA for human PLD1 (hPLD1) was cloned from HeLa cells (Hammond, S. M., Altshuller, Y. M., Sung, T-C., Rudge, S. A., Rose, K., Engebrecht, J., Morris, A. J., and Frohman, M. A. (1995) J. Biol. Chem. 270, 29640-29643). hPLD1 is stimulated by phosphatidylinositol 4,5-bisphosphate and the small GTP-binding protein known as ADP-ribosylation factor 1. Here we report the cloning and characterization of cDNA for a different type of PLD (rat PLD2 (rPLD2)) from rat brain. We synthesized highly degenerate amplimers corresponding to the conserved regions of eukaryote PLDs and performed polymerase chain reaction on a rat brain cDNA library. Using the amplified sequence as the probe, we cloned a rat brain cDNA clone that contained an open reading frame of 933 amino acids with an Mr of 105,992. The deduced amino acid sequence showed significant similarity to hPLD1 with a large deletion in the middle of the sequence. When the sequence was expressed in the fission yeast Schizosaccharomyces pombe, PLD activity was greatly increased. The activity was markedly stimulated by phosphatidylinositol 4, 5-bisphosphate, but not by ADP-ribosylation factor 1 and RhoA. Rat brain cytosol known to stimulate small GTP-binding protein-dependent PLD did not stimulate rPLD2 expressed in S. pombe. The transcript was detected at significant levels in brain, lung, heart, kidney, stomach, small intestine, colon, and testis, but at low levels in thymus, liver, and muscle. Only a negligible level was found in spleen and pancreas. Thus rPLD2 is a novel type of PLD dependent on phosphatidylinositol 4,5-bisphosphate, but not on the small GTP-binding proteins ADP-ribosylation factor 1 and RhoA.

Detergent effects on the light-harvesting chlorophyll A/B-protein complex crystallization revealed by fluorescence depolarization

Detergent effects on the pre-crystallization of light-harvesting chlorophyll a/b-protein complex (LHCII) were investigated through the fluorescence depolarization method. Stable LHCII crystals were formed in the media containing Triton X-100 (TX) or n-nonyl-beta-D-glucopyranoside (NG) and the crystallization efficients were dependent on their concentrations. The second virial coefficient of crystallizing system, estimated by the fluorescence depolarization analysis of LHCII, showed the most harmonious value under the condition yielding the most efficient crystallization of LHCII to suggest that some specific molecular interaction leading to the crystal growth would be induced according to the concentration of TX or NG.

Conformations and orientations of aromatic amino acid residues of tachyplesin I in phospholipid membranes

Tachyplesin I, an antibacterial and antiviral heptadecapeptide from the hemocyte debris of Tachypleus tridentatus, contains four aromatic amino acids (Trp2, Phe4, Tyr8, and Tyr13) which have been shown to be crucial for activity. In order to investigate conformations and orientations of the aromatic amino acid residues of tachyplesin I in lipid bilayers, its analogs, [Phe8]- and/or [Phe13]-tachyplesin(s) I in which Tyr8 and Tyr13 are replaced by Phe, were synthesized. Circular dichroism spectral studies showed that three peptides are considerably different in conformation in aqueous solution at pH 8.0 whereas they take similar conformations in the presence of neutral egg yolk phosphatidylcholine (EYPC) liposomes. Energy transfer kinetics showed that the distances of Trp2-Tyr8 and Trp2-Tyr13 are 16 A (max of 18.3 A, min of 15.1 A) and 18 A (max of 20.2 A, min of 16.6 A) in buffer but are 12 A (max of 15.2 A, min of 8.6 A) and 18 A (max of 22.9 A, min of 12.9 A), respectively, in the presence of acidic EYPC/EYPG (3:1) liposomes. Decay kinetics for Trp2 fluorescence indicated that Trp2 takes at least three conformations in buffer and in acidic liposomes where fractions of three Trp2 conformers vary by changing the medium from buffer to acidic liposomes. Although tachyplesin I is not in amphiphilic structure in buffer in spite of its rigid antiparallel beta-conformation, its interaction with lipid bilayers appears to induce amphiphilic structure via minor alteration of peptide backbone and side chain orientations, resulting in shortening the distance of Trp2-Tyr8.

p53 induced by ionizing radiation mediates DNA end-jointing activity, but not apoptosis of thyroid cells

To understand the effects of ionizing radiation on thyroid cells, we investigated the role of p53 in mediating apoptosis and in DNA repair following in vivo and in vitro irradiation of thyroid cells. In vitro exposure of human thyroid cells to ionizing radiation of up to 5-8 Gy failed to induce apoptosis in primary cells. The same results were obtained when the thyroid gland was irradiated in the intact rat. To explore the mechanism of failure of the wild-type p53 in inducing apoptosis in thyroid cells, we investigated the expression of apoptosis-related genes, bax, bcl-2 and fas/APO-1 following irradiation or induction of temperature-sensitive p53. The expression of Bax, Bcl-2 and Fas/APO-1 in human primary cultured thyroid cells did not change after irradiation. To further confirm the results, we established a clonal cell line (tsFRO) in which a temperature sensitive p53 (Val138) expression vector was stably transfected to a thyroid carcinoma cell line lacking endogenous p53. Incubation of tsFRO cells at the permissive temperature for three days, however, did not induce apoptosis although G1 arrest was noted. Although enhanced expression of the bax mRNA level was observed, the expression of Bax, Bcl-2 and Fas/APO-1 protein did not change by shifting tsFRO cells to permissive temperature as well as irradiated primary cells. Furthermore, DNA end-jointing ability was examined by transfection of linearized luciferase plasmid into tsFRO cells. Increased luciferase activity occurred when the cells were cultured at the permissive temperature, indicating that the wild-type p53 enhances DNA end-jointing activity. Our results indicate that the wild-type p53 does not lead to apoptosis but facilitates DNA end-jointing in thyroid cells. These results may reflect specific responses in thyroid cells following irradiation.

Indocyanine green angiography of retrobulbar vascular structures in severe myopia

PURPOSE

To evaluate angiographic findings of retrobulbar arteries and veins in severely myopic patients.

METHODS

We examined 416 severely myopic eyes (213 patients) with refractive errors greater than -8.25 diopters using indocyanine green videoangiography. A control group of 74 eyes (37 patients) had refractive errors within plano +/- 3 diopters. Four severely myopic patients underwent computed tomographic angiography to identify the entire intraorbital course of retrobulbar veins.

RESULTS

Of 416 severely myopic eyes, 231 (55.5%) exhibited retrobulbar arteries, which were tortuous and pulsatile behind the posterior pole of the globe. Retrobulbar arteries connected directly with choroidal arteries temporal to the macular area. In 17 of these 231 eyes, retrobulbar arteries were also observed nasal to the optic nerve head, continuous with the Zinn-Haller ring around the optic nerve head and directly connected with choroidal arteries. In 39 severely myopic eyes (31 patients), indocyanine green angiography disclosed retrobulbar veins, most of which coursed vertically just behind the posterior pole of the globe. These retrobulbar veins originated as an inferior vascular network of the inferior orbital vein and drained into the superior orbital vein in the upper orbit.

CONCLUSION

Retrobulbar arteries observed in this study were temporal and nasal short posterior ciliary arteries. Only the lateral collateral vein, which was one of the collateral channels between the superior and inferior orbital veins, was visible in severely myopic eyes. Indocyanine green angiography is useful in evaluating retrobulbar vascular structure in severely myopic eyes.

Molecular genetics of plasma cholesteryl ester transfer protein

Plasma cholesteryl ester transfer protein facilitates the transfer of cholesteryl ester from HDL to apolipoprotein B-containing lipoproteins, and is a key protein in the reverse cholesterol transport system. The importance of plasma cholesteryl ester transfer protein in lipoprotein metabolism was highlighted by the discovery of deficient individuals with a marked hyper-HDL-cholesterolemia. Cholesteryl ester transfer protein deficiency causes various abnormalities in the concentration, composition, and functions of both HDL and LDL. Its significance in atherosclerosis is still controversial. However, in-vitro evidence shows large cholesteryl ester-rich HDL particles in cholesteryl ester transfer protein deficiency are defective in cholesterol efflux. Recent epidemiological studies have demonstrated an increased incidence of coronary atherosclerosis in deficient patients. The current review will also focus on the molecular genetics of the protein.

De novo design, synthesis, and characterization of a pore-forming small globular protein and its insertion into lipid bilayers

The question of how to design a water-soluble globular protein remains. We report here the synthesis of a native-like and pore-forming small globular protein (SGP, 69 amino acid residues). The protein was designed to have four helices: a Trp-containing short hydrophobic helix in the middle surrounded by three Tyr-containing long basic amphiphilic helices. Size-exclusion chromatography and CD measurements indicated that in buffer solution SGP is monomeric with a 50% helical structure. SGP did not completely denature even at high temperature (90 degrees C) and at relatively high Gu x HCl concentration so that the denaturant concentration at the midpoint of the transition is 5 M. Dye binding studies and fluorescence energy transfer experiments showed that SGP possesses a hydrophobic binding site and its Trp of the central helix is present at a relatively hydrophobic region and accepts the energy from Tyr(s) in other amphiphilic helices, indicating that SGP takes a stable globular-like structure in aqueous solution. From the depth-dependent fluorescent studies using egg PC liposomes containing n-doxyl fatty acids and brominated phospholipid as quenchers, it was found that the hydrophobic central alpha-helix is able to enter spontaneously into the lipid bilayers and the Trp in the central alpha-helix is located at about the middle of the alkyl chain in the outer layer of the phospholipid bilayer. The peptide is also able to increase the membrane permeability with two modes of current (basal current and single ion channel) in planar phospholipid bilayers, indicating the spontaneous insertion of the protein into the lipid bilayer (basal current) and then the formation of a uniform size of channel pore (14 pS). SGP is useful as a basic and starting model to find good amino acid sequences that fold to a desired protein structure and to search translocation mechanisms from aqueous solution into lipid bilayers.

Analysis of drug permeation across Caco-2 monolayer: implication for predicting in vivo drug absorption

PURPOSE

The aim of the present work is to characterize in vitro drug permeation processes across Caco-2 monolayer and to identify the advantages of this cultured cell system in predicting in vivo drug absorption after oral administration.

METHODS

The passive permeability of various drugs through Caco-2 monolayer was measured using Ussing-type chambers and compared with that of the isolated rat jejunum and colon. The in vivo drug permeability to the intestinal membrane was estimated by means of an intestinal perfusion study using the rat jejunum.

RESULTS

In Caco-2 monolayer, drug permeability increased with increasing drug lipophilicity and showed a good linear relationship with the in vivo permeability. In contrast, in the isolated jejunum and colon, the permeability of high lipophilic drugs was almost constant and, propranolol, a drug with the highest lipophilicity, hardly passed through the jejunal membrane in vitro. As a result, there was no significant relationship between in vitro and in vivo drug permeability in rat jejunum. However, the amount of drugs accumulated in the jejunal mucosa increased with increasing drug lipophilicity even under the in vitro condition.

CONCLUSIONS

The permeation and the accumulation studies suggested that the rate-limiting process of in vitro permeation of lipophilic drugs through the intestinal membrane differs from that of in vivo drug absorption. On the other hand, drug permeation through Caco-2 monolayer, which consists of an epithelial cell layer and a supporting filter, is essentially the same process as that of in vivo drug absorption. We concluded that the simple monolayer structure of a cultured cell system provides a distinct advantage in predicting in vivo drug absorption.

High-density lipoproteins from probucol-treated patients have increased capacity to promote cholesterol efflux from mouse peritoneal macrophages loaded with acetylated low-density lipoproteins

To elucidate the anti-atherogenic effect of probucol, high-density lipoprotein (HDL) was isolated from probucol-treated patients (n = 14) and compared with that from control subjects (n = 12). The HDL obtained from probucol-treated patients was low in cholesteryl ester (CE) in comparison with that from control subjects (21.3 +/- 3.9 mol per cent vs. 27.6 +/- 3.2 mol% of total lipids. P < 0.001), and the peak diameters of patients' HDL were significantly smaller than those of control subjects on 4-30% non-denaturing polyacrylamide gradient gel electrophoresis (10.6 +/- 0.6 nm vs. 12.1 +/- 0.4 nm, P < 0.001). These data may be explained by the increased cholesteryl ester transfer protein (CETP) activities of probucol-treated patients (129 +/- 12% of control subjects, P < 0.001). The in vitro ability of HDL to remove CE from lipid-laden macrophages induced by incubation with acetylated low-density lipoprotein (Ac-LDL) was studied. The small and CE-poor HDL obtained from probucol-treated patients had a greater capacity to promote CE efflux from macrophages than did control HDL (59.8 +/- 6.9% vs. 44.2 +/- 5.4%, P < 0.01). Furthermore, the ability of HDL to promote cholesterol efflux correlated negatively with the CE content and particle diameter of HDL (r = -0.561 and r = -0.583 respectively; P < 0.01). When the inhibitory effect of HDL on the incorporation of [14C]-oleate into cellular cholesteryl ester was compared, the HDL from patients and control subjects inhibited CE formation to a similar extent. The enhanced ability of probucol-treated patients' HDL may, therefore, be involved in the acceleration of hydrolysis of the CE pool in macrophages. Taken together, we conclude that CETP plays a crucial role in making HDL more active in its anti-atherogenic function by reducing CE and making HDL smaller, and that probucol may enhance reverse cholesterol transport by activating CE transfer in vivo. The current study demonstrated, for the first time, that HDL modified by enhanced CETP activity in vivo is potentially anti-atherogenic.

A cDNA encoding fish fibroblast growth factor-2, which lacks alternative translation initiation

Here, we describe the isolation of a rainbow trout cDNA clone that contains the entire fibroblast growth factor-2 (FGF-2; basic FGF) coding region. Interestingly, the rainbow trout cDNA contains a translation stop codon just upstream of the primary initiating methionine codon and so cannot give rise to the longer forms of FGF-2 that are produced in mammals by alternative translation initiation at leucines farther upstream. Transfection of human FGF-2 cDNA into fish cells shows that fish cells can initiate protein synthesis at an upstream leucine CUG codon; surprisingly, however, synthesis is initiated only at the most 5' CUG and not at the two subsequent CUG codons or the methionine AUG codon also used in mammalian cells. Like other FGF-2 proteins, bacterially produced rainbow trout FGF-2 protein binds tightly to heparin-Sepharose and also promotes the proliferation of fibroblast cells. However, the protein differs from all others previously identified at amino acids 121-123, which are part of the proposed highly conserved receptor-binding domain. Comparisons of the efficacies of recombinant wild-type and mutant rainbow trout FGF-2 proteins demonstrate that these three amino acids are critical to the activity of FGF-2.

Oxidation of rat liver phospholipids: comparison of pathways in homogeneous solution, in liposomal suspension and in whole tissue homogenates

The oxidation of equivalent concentrations of phospholipids in homogeneous solution, in multilamellar liposomal suspension, and in rat liver homogenate was carried out under aerobic conditions at 37 degrees C in order to examine the biochemical fate of oxidized phospholipids. Rat liver phospholipids were extracted with chloroform and methanol, and oxidation in this homogeneous solution was initiated with a lipid-soluble radical initiator. The oxidation products were phosphatidylcholine hydroperoxide (PC-OOH) and phosphatidylethanolamine hydroperoxide (PE-OOH), which were quantified by HPLC separation using a hydroperoxide-specific chemiluminescence detector. Co-extracted alpha-tocopherol and ubiquinol-9 suppressed the formation of PC-OOH and PE-OOH until oxidatively exhausted. The oxidation of extracted rat liver phospholipids in multilamellar liposomal suspension initiated with the lipid-soluble initiator gave similar results, but with slower rates of antioxidant depletion and phospholipid hydroperoxide formation due to a lower efficiency of free radical production in liposomal membranes. In contrast, the oxidation of rat liver homogenate containing active tissue enzymes initiated by the addition of either free radical initiators or tert-butyl hydroperoxide gave phosphatidylcholine hydroxide, phosphatidylethanolamine hydroxide, and free fatty acid hydroxides as oxidation products. Exogenous PC-OOH added to the rat liver homogenate was reduced to phosphatidylcholine hydroxide with subsequent hydrolysis to its free fatty acid hydroxide. These results suggest that peroxidase and phospholipase enzymes play important roles in the repair of oxidatively damaged phospholipids in biomembranes.

[Anticancer drug-induced colitis--case report and review of the literature]

We encountered two chemotherapy cases related to anticancer drug-induced colitis. Case 1 was a 35-yo-female with a recurrence of ovarian cancer. She was treated with intraarterial infusion consisting of continuous 5-fluorouracil (250 mg/day 5 days/week x 4) following low-dose consecutive cisplatin (20 mg/day 5 days/ week x 1). The catheter was inserted into the abdominal aorta about 2 cm above the carina of the common iliac arteries. Six weeks after the start of chemotherapy, severe abdominal pain and melena occurred. Case 2 was a 68-yo-female with an endometrial cancer recurrence. The same intraarterial chemotherapy used in case 1 was was initiated. Four weeks after the start of chemotherapy, before intraarterial infusion of CDDP, she suffered from constipation and than diarrhea, abdominal pain and melena. Both cases were diagnosed as anticancer drug-induced colitis with the pathological findings from colon biopsy and the clinical course, and improved in about 1 month with the discontinuation of intraarterial infusion, fasting and TPN. Intraarterial infusion of only CDDP caused both patients no intestinal symptoms, so it is supposed that intraarterial infusion of 5-fluorouracil induced the colitis. Anticancer drug-induced colitis should be taken into consideration as a rare but possible course of chemotherapy-related complication with intraarterial infusion of 5-fluorouracil.

Influence of lactation on plasma phenobarbital concentrations in rats

The effect of lactation on the pharmacokinetics of phenobarbital (PB) after delivery was studied in female rats. Non-pregnant animals received PB 20 mg/kg/day twice for 6-7 days before mating, during pregnancy and after delivery. Chronic PB did not significantly influence changes in the body weight of rats after delivery. On the first post-delivery day, the plasma PB concentration in the PB-treated rats was significantly higher than that in PB-treated, non-pregnant rats (non-pregnant rats); and thereafter, it gradually decreased until ablactation on the 20th day. After ablactation, plasma PB concentrations gradually returned to the level before delivery. In PB-treated rats, pharmacokinetic parameters (Cmax, AUC0-12) of PB between 0 and 12 hr after a single oral administration were significantly decreased during lactation. These results suggest that PB administered during lactation is transferred in part to offspring through maternal milk.