Establishment and characterization of a human acute monocytic leukemia cell line (THP-1)

A human leukemic cell line (THP-1) cultured from the blood of a boy with acute monocytic leukemia is described. This cell line had Fc and C3b receptors, but no surface or cytoplasmic immunoglobulins. HLA haplotypes of THP-1 were HLA-A2, -A9, -B5, -DRW1 and -DRW2. The monocytic nature of the cell line was characterized by: (1) the presence of alpha-naphthyl butyrate esterase activities which could be inhibited by NaF; (2) lysozyme production; (3) the phagocytosis of latex particles and sensitized sheep erythrocytes; and (4) the ability to restore T-lymphocyte response to Con A. The cells did not possess Epstein-Barr virus-associated nuclear antigen. These results indicate that THP-1 is a leukemia cell line with distinct monocytic markers. During culture, THP-1 maintained these monocytic characteristics for over 14 months.

Mechanism of tumor-targeted delivery of macromolecular drugs, including the EPR effect in solid tumor and clinical overview of the prototype polymeric drug SMANCS

This review article describes three aspects of polymeric drugs. The general mechanism of the EPR (enhanced permeability and retention) effect and factors involved in the effect are discussed, in view of the advantages of macromolecular therapeutics for cancer treatment, which are based on the highly selective EPR-related delivery of drug to tumor. Also described are advantages of more general water-soluble polymeric drugs as primary anticancer agents, using SMANCS as an example. Last, SMANCS/Lipiodol is discussed with reference to the type of formulation for arterial injection with most pronounced tumor selective delivery, as well as its advantages, precautions, and side effects from the clinical standpoint.

Rings of negatively charged amino acids determine the acetylcholine receptor channel conductance

The structure-function relationship of the nicotinic acetylcholine receptor (AChR) has been effectively studied by the combination of complementary DNA manipulation and single-channel current analysis. Previous work with chimaeras between the Torpedo californica and bovine AChR delta-subunits has shown that the region comprising the hydrophobic segment M2 and its vicinity contains an important determinant of the rate of ion transport through the AChR channel. It has also been suggested that this region is responsible for the reduction in channel conductance caused by divalent cations and that segment M2 contributes to the binding site of noncompetitive antagonists. To identify those amino acid residues that interact with permeating ions, we have introduced various point mutations into the Torpedo AChR subunit cDNAs to alter the net charge of the charged or glutamine residues around the proposed transmembrane segments. The single-channel conductance properties of these AChR mutants expressed in Xenopus laevis oocytes indicate that three clusters of negatively charged and glutamine residues neighbouring segment M2 of the alpha-, beta-, gamma- and delta-subunits, probably forming three anionic rings, are major determinants of the rate of ion transport.

Effect of arterial administration of high-molecular-weight anticancer agent SMANCS with lipid lymphographic agent on hepatoma: a preliminary report

A clinical evaluation of arterial infusion of high-molecular-weight antitumor agent SMANCS dissolved in lipid lymphographic agent (thiodol) in 44 patients with mostly unresectable hepatoma is described. The treatment regimen demonstrated significant merits both therapeutically and diagnostically. Marked antitumor effects were shown in the decreased serum alpha-fetoprotein levels (86% of cases) and tumor size (95% of cases), and in survival period and histological findings. Furthermore, there was increased diagnostic sensitivity using CT scan, plain X-rays or ultrasound. The procedure of selective arterial administration of 3-4 mg of SMANCS in 3-4 ml of ethiodol per dose was simple to perform and was required only once every 3-4 weeks. Both ethiodol and the drug accumulated more selectively in tumor than in any other tissues and their activity remained for more than 3 weeks. Only minimal side-effects were associated with SMANCS and ethiodol during this study.

Location of a delta-subunit region determining ion transport through the acetylcholine receptor channel

The combination of complementary DNA expression and single-channel current analysis provides a powerful tool for studying the structure-function relationship of the nicotinic acetylcholine receptor (AChR) (refs 1-5). We have previously shown that AChR channels consisting of subunits from different species, expressed in the surface membrane of Xenopus oocytes, can be used to relate functional properties to individual subunits. Here we report that, in extracellular solution of low divalent cation concentration, the bovine AChR channel has a smaller conductance than the Torpedo AChR channel. Replacement of the delta-subunit of the Torpedo AChR by the bovine delta-subunit makes the channel conductance similar to that of the bovine AChR channel. To locate the region in the delta-subunit responsible for this difference, we have constructed chimaeric delta-subunit cDNAs with different combinations of the Torpedo and bovine counterparts. The conductances of AChR channels containing chimaeric delta-subunits suggest that a region comprising the putative transmembrane segment M2 and the adjacent bend portion between segments M2 and M3 is involved in determining the rate of ion transport through the open channel.

High incidence of silent aspiration in elderly patients with community-acquired pneumonia

Pneumonia is a major cause of death in the elderly. To investigate the role of silent aspiration in community-acquired pneumonia, we examined the occurrence of silent aspiration during sleep in 14 elderly patients with acute episode of pneumonia and 10 age-matched control subjects by a new technique using indium111 chloride. Scanning of the thorax demonstrated that 71% of patients aspirated, whereas aspiration was observed in only 10% of control subjects. The percentage of positive scans was significantly higher in patients with acute episode of pneumonia than in control subjects (p < 0.02). The results may indicate an important role of silent aspiration in the development of community-acquired pneumonia in the elderly.

Promotion of Intestinal Epithelial Cell Turnover by Commensal Bacteria: Role of Short-Chain Fatty Acids

The life span of intestinal epithelial cells (IECs) is short (3–5 days), and its regulation is thought to be important for homeostasis of the intestinal epithelium. We have now investigated the role of commensal bacteria in regulation of IEC turnover in the small intestine. The proliferative activity of IECs in intestinal crypts as well as the migration of these cells along the crypt-villus axis were markedly attenuated both in germ-free mice and in specific pathogen–free (SPF) mice treated with a mixture of antibiotics, with antibiotics selective for Gram-positive bacteria being most effective in this regard. Oral administration of chloroform-treated feces of SPF mice to germ-free mice resulted in a marked increase in IEC turnover, suggesting that spore-forming Gram-positive bacteria contribute to this effect. Oral administration of short-chain fatty acids (SCFAs) as bacterial fermentation products also restored the turnover of IECs in antibiotic-treated SPF mice as well as promoted the development of intestinal organoids in vitro. Antibiotic treatment reduced the phosphorylation levels of ERK, ribosomal protein S6, and STAT3 in IECs of SPF mice. Our results thus suggest that Gram-positive commensal bacteria are a major determinant of IEC turnover, and that their stimulatory effect is mediated by SCFAs.

Hepatocellular carcinoma detected by iodized oil

This study assesses the diagnostic value of Lipiodol (iodized oil) and computed tomography (CT) in detecting hepatocellular carcinoma (HCC). Twenty-four patients who were suspected of having HCC received injections of a small amount of Lipiodol, along with an antitumor agent, in the hepatic artery following routine celiac angiography. CT scans obtained 7-10 days after Lipiodol administration demonstrated HCC in distinct contrast to the surrounding noncancerous parenchyma. In particular, the CT-Lipiodol procedure disclosed many small HCC lesions that were not shown by celiac angiography, scintigraphy, CT with and without contrast medium enhancement, and ultrasonography. Although this procedure may miss very small or highly fibrotic lesions, it is recommended for patients suspected of having HCC and for patients for whom hepatic resection is being considered.

Selective targeting of anti-cancer drug and simultaneous image enhancement in solid tumors by arterially administered lipid contrast medium

Twenty-four patients with various solid tumors including metastatic liver cancer and cancer of the lung, gallbladder, and pancreas were treated with a lipophilic macromolecular drug, copoly(styrene-maleic acid) conjugated neocarzinostatin (SMANCS). The drug was dissolved in a lipid contrast medium Lipiodol and administered by catheterizing the respective feeding arteries under x-ray monitoring. The advantages of this therapy include: (1) selective deposition of Lipiodol with the anti-cancer drug in the target tumor, (2) a pronounced and long-lasting anti-cancer effect, (3) enhanced visualization of the tumor on x-ray examinations for a prolonged period which also facilitated the long-term follow-up, (4) semiquantitative evaluation of the dosage regimen by x-ray examination before further administration, (5) general applicability due to procedural simplicity, and (6) little side effect. Since the amount of Lipiodol and SMANCS used per administration for a patient (1.0-5.0 ml; 1.0-5.0 mg) was far less than the anticipated toxicity (LD50 of Lipiodol = 95 ml/60 kg, dog, intravenously; and that of SMANCS = 3.4 mg/kg, mouse, IV), no deleterious effects to such critical organs as the brain, heart, lung, liver, or kidneys were observed upon radiologic and general clinical examination.

Rat placentation: an experimental model for investigating the hemochorial maternal-fetal interface

The rat possesses hemochorial placentation with deep intrauterine trophoblast cell invasion and trophoblast-directed uterine spiral artery remodeling; features shared with human placentation. Recognition of these similarities spurred the establishment of in vitro and in vivo research methods using the rat as an animal model to address mechanistic questions regarding development of the hemochorial placenta. The purpose of this review is to provide the requisite background to help move the rat to the forefront in placentation research.

Studies on anticancer treatment with an oily anticancer drug injected into the ligated feeding hepatic artery for liver cancer

In six adult patients with nonresectable liver cancer, as well as in mature New Zealand white rabbits with implanted VX2 carcinoma in the liver, the artery feeding the hepatic lobe with the malignant lesion was ligated, and an oily contrast medium (Lipiodol Ultra-Fluid) was injected into the hepatoproximal lumen of the ligated artery of the liver with carcinoma. The oily contrast medium was detected in all the branches of the artery injected, and thereafter was found only in tumor tissue for 7 days experimentally and for 16 months clinically. Taking advantage of this phenomenon, the therapeutic effect of the injection of an oily anticancer drug (bleomycin oil suspension) into the hepatoproximal lumen of the ligated hepatic artery was investigated in rabbits with VX2 carcinoma of the liver. The mean concentration level of bleomycin in the tumor tissue was 2.4 +/- 0.4 microgram/g 1 week after the injection of bleomycin oil suspension (1.5 mg potency/kg) in three rabbits. However, its concentration level in nontumorous tissue of the liver was undetectably low in two rabbits, but 0.6 microgram/g in the third rabbit. The group of rabbits receiving an injection of bleomycin oil suspension into the ligated artery had a significantly longer mean survival time than those of the experimental group receiving an injection of saline solution of bleomycin into the ligated artery as well as the three other groups treated (P less than 0.02, N = 5 for each group). It may be concluded that an oily anticancer drug injected into the hepatoproximal lumen of the ligated hepatic artery can intensify the anticancer effects of a ligation of the hepatic artery for liver cancer.

The methanol-induced globular and expanded denatured states of cytochrome c: a study by CD fluorescence, NMR and small-angle X-ray scattering

Methanol-induced conformational transitions of cytochrome c(cyt c) at acidic pH values were investigated with a combined use of far and near-UV CD, fluorescence, NMR spectroscopy and small-angle X-ray scattering. At pH 3.0 and 25 degrees C, two methanol-induced non-native states were characterized. First, addition of methanol up to 25% (v/v) induced a compact denatured conformer (I(M)). Further addition of methanol transformed this I(M) state into the expanded and highly helical denatured state (H). The existence of the I(M) state was shown by the discrepancy in transition curves obtained from the ellipticity at 222 nm, the ellipticity at 282 nm, the tryptophan fluorescence monitored at 350 nm and the native peak intensity of the (1)H NMR spectrum. These CD, fluorescence and NMR results showed that the I(M) state has no specific tertiary structure but has a secondary structural content and tryptophan environment similar to those in the native state. The radius of gyration of the I(M) state, 17.7 angstroms, obtained from the Guinier plot of the small-angle X-ray scattering data was significantly smaller than that of the acid-denatured state (30.1 angstroms) and was closer to that of the native state (14.6 angstroms), showing that the I(M) state is compact. The Kratky plot for the I(M) state exhibited a bell-shaped profile, indicating a globular conformation. These structural features indicate that the structure of the I(M) state is quite similar to that of the anion-induced molten globule state of this protein. Furthermore the alcohol-denatured state (H) of cyt C in 60% (v/v) methanol was structurally characterized. Though the H state had a helical content much higher than the native state monitored by far-UV CD spectroscopy, the radius of gyration, 31.7 angstroms, was similar to that of the acid-denatured state, showing that this H state is an expanded denatured state. The Kratky plot for the H state did not show a clear peak, indicating a chain-like conformation. Thus we conclude that the H state has an expanded and chain-like conformation with a high helical content. Finally, we constructed a phase diagram of cyt c involving the native, I(M), acid-denatured and H states against pH and the methanol concentration. The result indicates that the I(M) state is found in the pH range from 2.5 to at least 4.5 with a pH-dependent optimum methanol concentration of 10 to 40%.

Localization in the II-III loop of the dihydropyridine receptor of a sequence critical for excitation-contraction coupling

Skeletal and cardiac muscles express distinct isoforms of the dihydropyridine receptor (DHPR), a type of voltage-gated Ca2+ channel that is important for excitation-contraction (EC) coupling. However, entry of Ca2+ through the channel is not required for skeletal muscle-type EC coupling. Previous work (Tanabe, T., Beam, K. G., Adams, B. A., Niidome, T., and Numa, S. (1990) Nature 346, 567-569) revealed that the loop between repeats II and III (II-III loop) is an important determinant of skeletal-type EC coupling. In the present study we have further dissected the regions of the II-III loop critical for skeletal-type EC coupling by expression of cDNA constructs in dysgenic myotubes. Because Ser687 of the skeletal II-III loop has been reported to be rapidly phosphorylated in vitro, we substituted this serine with alanine, the corresponding cardiac residue. This alanine-substituted skeletal DHPR retained the ability to mediate skeletal-type EC coupling. Weak skeletal-type EC coupling was produced by a chimeric DHPR, which was entirely cardiac except for a small amount of skeletal sequence (residues 725-742) in the II-III loop. Skeletal-type coupling was stronger when both residues 725-742 and adjacent residues were skeletal (e.g. a chimera containing skeletal residues 711-765). However, residues 725-742 appeared to be critical because skeletal-type coupling was not produced either by a chimera with skeletal residues 711-732 or by one with skeletal residues 734-765.

Grf40, A novel Grb2 family member, is involved in T cell signaling through interaction with SLP-76 and LAT

We molecularly cloned a new Grb2 family member, named Grf40, containing the common SH3-SH2-SH3 motif. Expression of Grf40 is predominant in hematopoietic cells, particularly T cells. Grf40 binds to the SH2 domain-containing leukocyte protein of 76 kD (SLP-76) via its SH3 domain more tightly than Grb2. Incidentally, Grf40 binds to linker for activation of T cells (LAT) possibly via its SH2 domain. Overexpression of wild-type Grf40 in Jurkat cells induced a significant increase of SLP-76-dependent interleukin (IL)-2 promoter and nuclear factor of activated T cell (NF-AT) activation upon T cell receptor (TCR) stimulation, whereas the COOH-terminal SH3-deleted Grf40 mutant lacked any recognizable increase in IL-2 promoter activity. Furthermore, the SH2-deleted Grf40 mutant led to a marked inhibition of these regulatory activities, the effect of which is apparently stronger than that of the SH2-deleted Grb2 mutant. Our data suggest that Grf40 is an adaptor molecule involved in TCR-mediated signaling through a more efficient interaction than Grb2 with SLP-76 and LAT.

Clinical and genetic characterization of adult-onset leukoencephalopathy with axonal spheroids and pigmented glia associated with CSF1R mutation

Background and purpose

The clinical characteristics of colony stimulating factor 1 receptor (CSF1R) related adult‐onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) have been only partially elucidated.

Methods

Clinical data from CSF1R mutation carriers who had been seen at our institutions or reported elsewhere were collected and analysed using a specific investigation sheet to standardize the data.

Results

In all, 122 cases from 90 families with CSF1R mutations were identified. The mean age of onset was 43 years (range 18–78 years), the mean age at death was 53 years (range 23–84 years) and the mean disease duration was 6.8 years (range 1–29 years). Women had a significantly younger age of onset than men (40 vs. 47 years, P = 0.0006, 95% confidence interval 3.158–11.177). There was an age‐dependent penetrance that was significantly different between the sexes (P = 0.0013). Motor dysfunctions were the most frequent initial symptom in women whose diseases began in their 20s. Thinning of the corpus callosum, abnormal signalling in pyramidal tracts, diffusion‐restricted lesions and calcifications in the white matter were characteristic imaging findings of ALSP. The calcifications were more frequently reported in our case series than in the literature (54% vs. 3%). Seventy‐nine per cent of the mutations were located in the distal part of the tyrosine kinase domain of CSF1R (102 cases). There were no apparent phenotype−genotype correlations.

Conclusions

The characteristics of ALSP were clarified. The phenotype of ALSP caused by CSF1R mutations is affected by sex.

Conjugation of Enzymes on Polymer Nanoparticles Covered with Phosphorylcholine Groups

We investigated the bioconjugation of enzymes on polymer nanoparticles covered with bioinert phosphorylcholine groups. A water-soluble amphiphilic phospholipid polymer (PMBN) was specially designed for preparation of nanoparticles and conjugation with enzymes on them. The PMBN was prepared by random copolymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC), n-butyl methacrylate, and p-nitrophenylester bearing methacrylate. The PMBN was used as an emulsifier and a surface modifier to prepare the poly(l-lactic acid) nanoparticles by a solvent evaporation technique in aqueous medium. The nanoparticles covered with phosphorylcholine groups were stably dispersed in an aqueous solution and a phosphate buffered saline. The diameter and surface zeta-potential of the nanoparticles were ca. 200 nm and -6 mV, respectively. The p-nitrophenyl ester groups, which are active ester units for the amino groups of the protein, were located at the surface of the nanoparticles. Both acetylcholine esterase and choline oxidase were co-immobilized (dual-mode conjugation) by the reaction between the p-nitrophenyl ester group and the amino group of these enzymes. The enzymatic reactions on the nanoparticles were followed using a microdialysis biosensor system with a microtype hydrogen peroxide electrode in the probe. The nanoparticles conjugated with these enzymes could detect the acetylcholine chloride as hydrogen peroxide, which is a product of the enzymatic reactions on the surface of the nanoparticles in the probe. Namely, continuous enzyme reactions could be occurring on the surface of the nanoparticles. It is concluded that the nanoparticles are a promising tool for a highly sensitive and microdiagnostic system.

Image enhancement in computerized tomography for sensitive diagnosis of liver cancer and semiquantitation of tumor selective drug targeting with oily contrast medium

A new type of anticancer agent with an amphiphilic nature, poly(styrene-co-maleic acid)-conjugated neocarzinostatin (Smancs), was dissolved in lipid contrast medium Lipiodol (Smancs/Lpd, Gelbet Co., Paris, France). This medium was injected arterially and found to be an invaluable tool for highly sensitive computerized tomography (CT) image analysis of tumors. After the administration, CT images revealed high-density areas which corresponded to the location and size of liver cancer, the smallest being 4 mm in diameter. The deposition pattern of Smancs/Lpd in liver cancers by CT was classified into three types. In type A, Lipiodol was distributed relatively even in the tumor lesion, whereas in type B it was accumulated predominantly around the tumor's periphery although the central portion remaining low in density. A few cases exhibited type C pattern, which was a mixture of types A and B. Type A was found essentially in primary liver cancer, and types B and C in secondary liver cancer. Thus, the CT pattern was found to be useful for differential diagnosis. For a sufficient therapeutic effect, 0.08 ml of Smancs/Lpd per cm2 of the maximal CT cross-section of the tumor area was found to be necessary. As a routine protocol after Smancs/Lpd administration, CT scanning was recommended for primary liver cancer initially at 1 week and then once every month. Secondary liver cancer required more frequent CT follow-ups after the administration (on the third day, after 1 and 2 weeks, and every month) due to relatively rapid disappearance of the stain than in the primary liver cancer.

Primary structure and functional expression of the alpha-, beta-, gamma-, delta- and epsilon-subunits of the acetylcholine receptor from rat muscle

The isolation and characterization of five clones carrying sequences of the alpha-, beta-, gamma-, delta- and epsilon-subunit precursors of the rat muscle acetylcholine receptor (AChR) are described. The deduced amino acid sequences indicate that these polypeptides contain 457-519 amino acids and reveal the structural characteristics common to subunits of ligand-gated ion channels. The pattern of subunit-specific mRNA levels in rat muscle shows characteristic changes during development and following denervation, suggesting that innervation of muscle reduces the expression of the alpha-, beta- and delta-subunit mRNAs, suppresses the expression of the gamma-subunit mRNA, and induces expression of epsilon-subunit mRNA. Subunit-specific cRNAs generated in vitro were injected into Xenopus laevis oocytes, resulting in the assembly of two functionally different AChR channel subtypes. The AChR gamma, composed of the alpha-, beta-, gamma- and delta-subunits, has functional properties similar to those of the native AChRs in fetal muscle. The AChR epsilon, composed of alpha-, beta-, delta- and epsilon-subunits, corresponds to the end-plate channel of the adult muscle. Thus in rat skeletal muscle the motor nerve regulates the expression of two functionally different AChR subtypes with different molecular composition by the differential expression of subunit-specific mRNAs.

Novel interaction of the voltage-dependent sodium channel (VDSC) with calmodulin: does VDSC acquire calmodulin-mediated Ca2+-sensitivity?

The voltage-dependent sodium channel (VDSC) interacts with intracellular molecules to modulate channel properties and localizations in neuronal cells. To study protein interactions, we applied yeast two-hybrid screening to the cytoplasmic C-terminal domain of the main pore-forming alpha-subunit. We found a novel interaction between the C-terminal domain and calmodulin (CaM). By two-hybrid interaction assays, we specified the interaction site of VDSC in a C-terminal region, which is composed of 38 amino acid residues and contains both IQ-like and Baa motifs. Using a fusion protein of the C-terminal domain, we showed that interaction with CaM occurred in the presence and absence of Ca(2+). Two synthetic peptides, each covering the IQ-like (NaIQ) or the Baa motifs (NaBaa), were used to examine the binding property by a gel mobility shift assay. Although the NaIQ and NaBaa sequences are overlapped, NaBaa binds only to Ca(2+)-bound Ca(2+)CaM, whereas NaIQ binds to both Ca(2+)CaM and Ca(2+)-free apoCaM. Fluorescence spectroscopy of dansylated CaM showed Ca(2+)-dependent spectral changes not only for NaBaa.CaM but also for NaIQ.CaM. The results, taken together with other results, indicate that whereas the NaBaa.CaM complex is formed in a Ca(2+)-dependent manner, the NaIQ.CaM complex has two conformational states, distinct with respect to the peptide binding site and the CaM conformation, depending on the Ca(2+) concentration. These observations suggest the possibility that VDSC is functionally modulated through the direct CaM interaction and the Ca(2+)-dependent conformational transition of the complex.

A ring of uncharged polar amino acids as a component of channel constriction in the nicotinic acetylcholine receptor

The channel pore of the nicotinic acetylcholine receptor (AChR) has been investigated by analysing single-channel conductances of systematically mutated Torpedo receptors expressed in Xenopus oocytes. The mutations mainly alter the size and polarity of uncharged polar amino acid residues of the acetylcholine receptor subunits positioned between the cytoplasmic ring and the extracellular ring. From the results obtained, we conclude that a ring of uncharged polar residues comprising threonine 244 of the alpha-subunit (alpha T244), beta S250, gamma T253 and delta S258 (referred to as the central ring) and the anionic intermediate ring, which are adjacent to each other in the assumed alpha-helical configuration of the M2-containing transmembrane segment, together form a narrow channel constriction of short length, located close to the cytoplasmic side of the membrane. Our results also suggest that individual subunits, particularly the gamma-subunit, are asymmetrically positioned at the channel constriction.

Preparation of nanoparticles composed with bioinspired 2-methacryloyloxyethyl phosphorylcholine polymer

The poly(L-lactic acid) nanoparticles immobilized with 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer, which has excellent blood compatibility, were prepared by a solvent evaporation technique using the water-soluble amphiphilic MPC polymer as an emulsifier and a surface modifier. The diameter and zeta-potential of the obtained nanoparticles strongly depended on the concentration of the MPC polymer. When the nanoparticles were prepared in 1.0 mg/ml of an MPC polymer aqueous solution, the diameter was 221 nm which was determined by atomic force microscopy and dynamic light scattering measurements. The X-ray photoelectron spectroscopic analysis indicated that the phosphorylcholine groups of the MPC unit were located at the surface of the nanoparticles, that is, the MPC polymer was immobilized on the PLA particles and the surface zeta-potential was -2.5 mV. Various hydrophobic fluorescence probes could permeate through the MPC polymer layer and adsorb on the PLA surface. The amount of bovine serum albumin adsorbed on the nanoparticles was significantly smaller compared with that on the conventional polystyrene nanoparticles. It is suggested that the nanoparticles immobilized with the MPC polymer have the potential for use as both a novel drug carrier and diagnostic reagent which can come in contact with blood components.

Effect of the recombinant vaccinia viruses that express HTLV-I envelope gene on HTLV-I infection

The human T-lymphotropic virus type I (HTLV-I) is etiologically linked to adult T-cell leukemia (ATL). To develop a vaccine against ATL, we constructed recombinant vaccinia viruses containing the envelope gene of HTLV-I in the vaccinia virus hemagglutinin (HA) gene, a new site where foreign genes can be inserted. A single inoculation of the recombinant virus induced antibodies to the env proteins of HTLV-I in rabbits and had a protective effect against HTLV-I infection.

Comparison of human, simian, and bovine rotaviruses for requirement of sialic acid in hemagglutination and cell adsorption

Human rotaviruses (Wa, KUN, MO) showed hemagglutination (HA) only with fixed 1-day-old chicken erythrocytes, and their HA activities were completely destroyed by trypsin activation of virions. Simian SA-11 and bovine NCDV had HA activities not only against fixed erythrocytes but also against fresh erythrocytes from various species. Their HA activities against fixed erythrocytes were also inhibited by trypsin activation, but those against fresh erythrocytes were not. Neuraminidase treatment of fixed erythrocytes did not inhibit HA by trypsin-untreated rotaviruses. In contrast, HA of fresh human erythrocytes by SA-11 and NCDV was completely inhibited by neuraminidase treatment of erythrocytes or glycophorin A, the major erythrocyte sialoglycoprotein. Adsorption and infection of SA-11 and NCDV to monkey kidney MA104 cells were also inhibited by neuraminidase treatment of cells. Adsorption and infection of human rotaviruses were not, however, affected by treatment of cells with neuraminidase from Vibrio cholerae or Arthrobacter ureafaciens or with potassium periodate. Therefore, HA of fixed chicken erythrocytes by trypsin-untreated human and animal rotaviruses may be independent of sialic acids, whereas that of fresh erythrocytes by SA-11 and NCDV is sialic acid dependent and probably mediated by glycophorin A. Sialic acids also constitute an essential part of the cellular receptors for SA-11 and NCDV, whereas those for human rotaviruses were quite resistant to treatments known to destroy major types of sialic acids.

Isolation of human rotavirus subgroups 1 and 2 in cell culture

One strain of human rotavirus subgroup 1 (KUN) and one strain of subgroup 2 (MO) were isolated with the MA104 cell line, a fetal rhesus monkey kidney cell line. Their subgroup specificities and RNA patterns were identical to those of rotaviruses present in stools before cultivation. Distinct cytopathic effects consisting of obscure cell boundaries, cell fusion, cell rounding, cell detachment, and lytic foci were recognized at passage 3 of MO and passage 6 of KUN. No differences in cytopathic changes were found between the two isolates.

Rings of anionic amino acids as structural determinants of ion selectivity in the acetylcholine receptor channel

To gain an insight into the molecular basis of the weak but significant selectivity among alkali metal cations of the nicotinic acetylcholine receptor (AChR) channel, we have determined single-channel conductance and permeability ratios for alkali metal cations on specifically mutated Torpedo californica AChR channels expressed in Xenopus oocytes. The mutations involved charged and polar side chains in the three anionic rings (extracellular, intermediate and cytoplasmic ring) which have previously been found to determine the rate of K+ transport through the AChR channel. The results obtained reveal that mutations in the intermediate ring exert much stronger effects on ion selectivity than do mutations in the extracellular and the cytoplasmic ring. The experimental results, together with simulations of the channel's energy profile, suggest that the amino acid residues forming the intermediate ring come into close contact with permeating cations and possibly represent part of the physical correlate of the postulated selectivity filter in the AChR channel.