Dihydropyridine-sensitive skeletal muscle Ca channels in polarized planar bilayers. 1. Kinetics and voltage dependence of gating

Rabbit skeletal muscle transverse tubule (T) membranes were fused with planar bilayers. Ca channel activity was studied with a "cellular" approach, using solutions that were closer to physiological than in previous studies, including asymmetric extracellular divalent ions as current carriers. The bilayer was kept polarized at -80 mV and depolarizing pulses were applied under voltage clamp. Upon depolarization the channels opened in a steeply voltage-dependent manner, and closed rapidly at the end of the pulses. The activity was characterized at the single-channel level and on macroscopic ensemble averages of test-minus-control records, using as controls the null sweeps. The open channel events had one predominant current corresponding to a conductance of 9 pS (100 mM Ba2+). The open time histogram was fitted with two exponentials, with time constants of 5.8 and 30 ms (23 degrees C). Both types of events were virtually absent at -80 mV. The average open probability (fractional open time) increased sigmoidally from 0 to a saturation level of 0.08, following a Boltzmann function centered at -25 mV and with a steepness factor of 7 mV. Ensemble averages of test-minus-control currents showed a sigmoidal activation followed by inactivation during the pulse and deactivation (closing) after the pulse. The ON time course was well fitted with "m3h" kinetics, with tau m = 120 ms and tau h = 1.2 s. Deactivation was exponential with tau = 8 ms. This study demonstrates a technique for obtaining Ca channel events in lipid bilayers that are strictly voltage dependent and exhibit most of the features of the macroscopic ICa. The technique provides a useful approach for further characterization of channel properties, as exemplified in the accompanying paper, that describes the consequences on channel properties of phosphorylation by cAMP dependent protein kinase.

Intravenous recombinant tissue-type plasminogen activator in acute myocardial infarction

The efficacy and safety of intravenously administered recombinant tissue-type plasminogen activator (rt-PA, Boehringer Ingelheim Corp.) was investigated in 10 patients with acute myocardial infarction (AMI). rt-PA was given as a 10 mg bolus dose followed by infusions of 50 mg, 20 mg and 20 mg in three successive hours. All patients underwent baseline coronary angiography before thrombolytic therapy. Ninety minutes after the initiation of rt-PA infusion, recanalization of infarct-related coronary arteries as confirmed by angiography was achieved in 7 patients. The largest reduction in circulating fibrinogen was observed 4 to 6 h after the start of rt-PA infusion--14.3%. Moderate hemorrhage at the sites of arterial puncture occurred in 2 cases, probably as a result of heparin anticoagulation. No other side effects occurred. So rt-PA is an effective and safe thrombolytic agent.

[Chemical constituents of Swertia tetraptera Maxim. var. xinglongensis Ji Ma et R. N. Zhao]

Five natural products were isolated from S. tetraptera var. xinglongensis of which four were proved to be oleanolic acid, 1,3-dihydroxy-4,7-dimethoxyxanthone, 1-hydroxy-2,3,5-trimethoxyxanthone and beta-sitosterol. 1,3-dihydroxy-4,7-dimethoxyxanthone has been obtained for the first time from the genus Swertia.

Moving grating and dc external field in photorefractive GaP at 633 nm

We demonstrate that the photorefractive effect in GaP crystal at 633 nm can be enhanced using an externally applied dc field and a moving grating. A two-beam coupling gain coefficient of 2.5 cm(-1) and a steady-state phase-conjugate reflectivity of 1.9% were obtained.

Synthesis of (+/-)-N-2-methylpropyl-N-1'-methylacetonyl-nitrosamine

N-2-methylpropyl-N-1-methylacetonyl-nitrosamine (NMAMPA), first isolated from moldy and normal foods, was synthesized by chemical means. The structure and molecular weight of the synthetic NMAMPA were elucidated by spectrometry. A combination of spectral and chromatographic data indicated that the synthetic NMAMPA is identical to that obtained naturally. Synthetic NMAMPA is a racemic modification, and a carcinogen which can induce esophageal and forestomach cancer in rats.

Oncofetal expression of the human intestinal mucin glycoprotein antigens in gastrointestinal epithelium defined by monoclonal antibodies

A mucin preparation from a colonic adenocarcinoma was used to prepare monoclonal antibodies (MAbs) that reacted specifically either with normal adult small-intestine mucin antigen(s) (SIMA), or normal adult large-intestine mucin antigen(s) (LIMA). Both SIMA and LIMA show a unique oncofetal pattern of expression. Thus SIMA was expressed in early fetal stomach, large and small intestines but thereafter only in the normal small intestine. SIMA expression was detected immunohistochemically in cancers of the colorectum (82/112) and stomach (48/86). LIMA was detected in the stomach of the early fetus but thereafter only in the normal large intestine. LIMA expression was detected in 61/86 cancers of the stomach. Moreover, both SIMA and LIMA were expressed inappropriately in mucosa adjacent to tumors, indicative of the detection of possible pre-malignant epithelium. We used a sandwich ELISA and biochemical procedures to show that the SIMA and LIMA molecules were large extensively glycosylated multi-unit mucin glycoproteins that differed markedly from each other. SIMA, whether extracted from normal small-intestine or colonic cancers, had a molecular weight above 1.000 kDa, a mean buoyant density 1.33 g/ml and s value of 4.8. LIMA had a molecular weight above 10.000 kDa, a mean buoyant density 1.45 g/ml and an s value 9.5. The SIMA and LIMA epitopes were judged to be carbohydrate in nature by reason of their resistance to harsh physical chemical treatments or protease digestion, and sensitivity to periodate oxidation, neuraminidase or beta elimination. Only the SIMA epitope was sensitive to neuraminidase. In conclusion, MAbs to carbohydrate-dependent epitopes on SIMA and LIMA identify the oncofetal pattern of expression of these distinct intestinal mucin glycoproteins in colonic and gastric carcinoma. These MAbs will be useful in further studies of the significance of oncofetal mucin expression during carcinogenesis.

Antibody penetration of viable human cells. I. Increased penetration of human lymphocytes by anti-RNP IgG

Antibody penetration of viable cells and interaction with intracellular antigens may have major consequences for immunopathological processes in connective tissue diseases. We have reported previously that antibody can penetrate viable human lymphocytes. To assess further the role of antinuclear antibodies in this process, peripheral blood lymphocytes (PBMC) were incubated with FITC-conjugated IgG fractions from sera containing anti-RNP (anti-RNP IgG), Ro(SS-A), La(SS-B) and dsDNA antibodies and control sera for 24 h. Using crystal violet to quench cell surface staining, intracellular fluorescence of viable lymphocytes was quantified on the flow cytometer. It was noted that anti-RNP IgG entered 46.4 +/- 7.2% of lymphocytes which was significantly higher than anti-Ro(SS-A) (29.9 +/- 4.1%, P less than 0.05), La(SS-B) (22.0 +/- 7.5%, P less than 0.01) IgG and control IgG (28.8 +/- 2.1%, P less than 0.05) and not statistically different from anti-dsDNA IgG (32.6 +/- 14.3%). Inhibition experiments showed that the increased number of cells penetrated by anti-RNP IgG was a specific process. Time-course studies showed that anti-RNP IgG entry into cells was different from pooled control IgG. With anti-RNP IgG, positive-staining lymphocytes gradually increased in number from 12 to 24 h incubation, whilst with pooled control IgG, the peak was reached within 5 min. Dual staining experiments suggested that whereas both anti-RNP IgG and pooled control IgG entered B and NK cells, anti-RNP IgG also entered T cells. Using IgG F(ab')2 and Fc fragments from either anti-RNP IgG or pooled control IgG to compete with their FITC-conjugated counterparts indicated that the entry of anti-RNP IgG into-viable cells appeared to involve both F(ab')2 and Fc fragments, and pooled control IgG depended exclusively on the Fc portion of IgG. Further investigation by incubating anti-RNP IgG with 35S-methionine-labelled monocyte-depleted PBMC (MD-PBMC) suggested that anti-RNP IgG might react with the corresponding antigens either on the cell surface or within the cytoplasm.

Generating yeast transcriptional activators containing no yeast protein sequences

We previously reported that roughly 1% of the short peptides encoded by Escherichia coli genomic DNA fragments act as transcriptional activating regions in yeast when fused to GAL4(1-147), a DNA-binding portion of the yeast transcriptional activator GAL4 (ref. 1). Struhl questioned the conclusion that we had identified new transcriptional activating sequences that function in the absence of yeast transcriptional activating sequences. His criticism was based on two considerations: first, GAL4(1-147) contains an acidic segment (and subsequent experiments have shown that this region contains a weak activating region in vitro); second, attempts to isolate new activating regions failed when the DNA-binding domain of a bacterial repressor, LexA(1-87), was used as the DNA-binding unit. We report here a repeat of our original experiment using the complete LexA molecule LexA(1-202) as the DNA-binding region, instead of GAL4(1-147) or LexA(1-87). We find that, as in the original experiment, about 1% of the short peptides encoded by E. coli genomic fragments act as transcriptional activating regions when fused to intact LexA. All of the new activating regions whose sequences we determined bore an excess of acidic amino acids (see Table 1).

Strategy for developing a genetically-engineered whole-virus vaccine against HIV

The production of genetically-engineered, noninfectious virions of human immunodeficiency virus (HIV) represents a novel approach to the development of a safe and effective vaccine for the acquired immune deficiency syndromes (AIDS). Insofar as preparations of inactivated simian immunodeficiency virus (SIV) are now demonstrating protection in immunization-challenge studies in rhesus monkeys, a safe preparation of noninfectious HIV virions produced in a genetically-engineered cell line becomes a logical candidate vaccine for studies in humans. These particles, or pseudovirions, offer distinct advantages over the use of inactivated HIV for human AIDS vaccines. Guarantees of safety without the requirement for inactivation and their potential for structural modification for the modulation of immunogenicity are compelling reasons for the acceptance of HIV pseudovirions as a candidate vaccine in humans.

Moving grating for enhanced holographic recording in cerium-doped Sr(0.6)Ba(0.4)Nb(2)O(6)

We demonstrate that holographic recording in photorefractive materials can be improved by using a moving grating to reduce energy coupling. In cerium-doped Sr(0.6)Ba(0.4)Nb(2)O(6) under an applied dc electric field, experimental and theoretical results show that the proper grating velocity can maximize the modulus and the real part of the spacecharge field while reducing the imaginary component of the space-charge field (and energy coupling) to zero. Avoiding energy transfer between the recording beams allows us to maintain maximum contrast throughout the crystal, producing a uniform, high-index-modulation grating with enhanced diffraction efficiency and superposition properties.

[Chemical constituents of Osbeckia chinensis L]

Five constituents, 2-furoic acid, succinic acid, ursolic acid, quercetin and daucosterol were isolated and identified from Osbeckia chinensis. All of them are reported to have been found from this plant for the first time.

Opposing regulatory functions of positive and negative elements in UASG control transcription of the yeast GAL genes

The yeast GAL1 and GAL10 genes are transcribed at a remarkably low basal level when galactose is unavailable and are induced by over 4 orders of magnitude when it becomes available. Approximately six negative control elements (designated GAL operators GALO1 to GALO6) are located adjacent to or overlapping four binding sites for the transcription activator GAL4 in the GAL upstream activating sequence UASG. The negative control elements contribute to the broad range of inducibility of GAL1 and GAL10 by inhibiting two GAL4/galactose-independent activating elements (GAE1 and GAE2) in UASG. In turn, multiple GAL4-binding sites in UASG are necessary for GAL4 to overcome repression by the negative control elements under fully inducing conditions. When glucose in addition to galactose is available (repressing conditions), the ability of GAL4 to activate transcription is diminished as a result of its reduced affinity for DNA and the reduced availability of inducer. Under these conditions, the negative control elements inhibit transcriptional activation from the glucose-attenuated GAL4 sites, thus accounting at least in part for glucose repression acting in cis. A normal part of transcriptional regulation of the GAL1 and GAL10 genes, therefore, appears to involve a balance between the opposing functions of positive and negative control elements.

Direct binding of verapamil to the ryanodine receptor channel of sarcoplasmic reticulum

Radioligand binding experiments and single channel recordings demonstrate that verapamil interacts with the ryanodine receptor Ca2+ release channel of the sarcoplasmic reticulum of rabbit skeletal muscle. In isolated triads, verapamil decreased binding of [3H]Ryanodine with an IC50 of approximately 8 microM at an optimal pH 8.5 and pCa 4.3. Nitrendipine and d-cis-diltiazem did not interfere with binding of [3H]Ryanodine to triads, suggesting that the action of verapamil does not involve the dihydropyridine receptor. Single channel recordings showed that verapamil blocked Ca2+ release channels by decreasing open probability, duration of open events, and number of events per unit time. A direct interaction of verapamil with the ryanodine receptor peptide was demonstrated after purification of the approximately 400 kDa receptor protein from Chaps-solubilized triads. The purified receptor displayed high affinity for [3H]Ryanodine with a Kd of approximately 5 nM and a Bmax of approximately 400 pmol/mg. Verapamil and D600 decreased [3H]Ryanodine binding noncompetitively by reducing the Bmax. Thus the presence of binding sites for phenylalkylamines in the Ca2+ release channel was confirmed. Verapamil blockade of Ca2+ release channels may explain some of the paralyzing effects of phenylalkylamines observed during excitation-contraction coupling of skeletal muscle.

[Analysis of brain CT in 120 patients with human cysticercosis]

A study on brain CT was made in 120 patients of human cysticercosis, which is a rare disease in Japan and clinical symptoms and laboratory data for the diagnosis were also discussed. From the point of therapeutic view, we proposed a new differentiation on brain CT of human cysticercosis, which is divided into two groups according to the alive or dead parasite. Furthermore, we proposed a new type named multiple large and small cysts type on brain CT. The idea of diagnostic standard was made integrating brain CT image, clinical symptoms and laboratory data.

Association of transport-defective light chains with immunoglobulin heavy chain binding protein

Immunoglobulin light chains are usually secreted from cells when they are synthesized alone or in molar excess of heavy chains, but, there have been reports of nonsecreted light chains. We wished to determine whether immunoglobulin heavy chain binding protein (BiP), which blocks the transport of free heavy chains, might be responsible for the lack of secretion of some light chains. In two murine lymphoid cell lines that synthesize but do not secrete immunoglobulin light chains, the free light chain polymers were found bound to BiP. Examination of 20 other cell lines and hybridomas failed to disclose any cells synthesizing free or excess light chains that associated with BiP, in all cases the free light chains were secreted as dimers. Despite their association with BiP and their blocked secretion, the aberrant light chains could combine with heavy chains and could be secreted as intact Ig molecules. Thus, while light chains do not usually express signals which allow them to bind to BiP, it appears that such signals can be expressed on certain light chains, resulting in their combination with BiP and blocked secretion. When single chain mutant cell lines are isolated from parental lines producing both heavy and light chains, they are almost always light chain producers suggesting that free heavy chains are much more toxic than free light chains. In both PC700 and P3X63Ag cells, however, clones that have lost either heavy chains or transport-defective light chains are present at the same frequency. Our findings that the light chains in both of these lines are associated with BiP raise the possibility that BiP actually contributes to heavy chain toxicity instead of preventing it.

[Antitumor action of lignum sappan]

The aqueous extract of lignum sappan can kill cell lines of HL-60, K562, L929 and Yac-1 at the concentration of 2 microliters/ml. The survival time of mice bearing EAC is increased by 185% (P less than 0.01) by ip 0.2 ml/mouse x 7d. The three-stage sequential test standard can be passed smoothly.

Klinefelter's syndrome and primary central nervous system lymphoma

Klinefelter's syndrome is known to be associated with various malignancies including male breast cancer and germ cell tumour. We report a patient with Klinefelter's syndrome who developed a primary B-cell lymphoma of the central nervous system (CNS). To the best of our knowledge, this is the first case of primary CNS lymphoma in Klinefelter's syndrome.

Rescue of bicoid mutant Drosophila embryos by bicoid fusion proteins containing heterologous activating sequences

The maternal gene bicoid (bcd) determines pattern in the anterior half of the Drosophila embryo. It is reported here that the injection of bcd mutant embryos with messenger RNAs that encode proteins consisting of heterologous acidic transcriptional activating sequences fused to the DNA-binding portion of the bcd gene product, can completely restore the anterior pattern of the embryo.