Improved processing of the steady-state evoked potential

Two related procedures for estimating the parameters of steady-state evoked potentials (SSEPs) are introduced. The first procedure involves an initial stage of digital bandpass filtering followed by a Discrete Fourier Transform analysis. In the second method, a high resolution method based on parametric modelling is applied to the filtered data. The digital pre-filter consists of a non-phase shifting Chebychev bandpass filter. The parametric modelling method considers the evoked-response-plus-noise distribution to consist of a set of exponentially damped sinusoids. The frequency, amplitude, phase and damping factors of these components are estimated by calculating the mean of the forward and backward prediction filters and linear regression. We compared the signal-to-noise ratio (SNR) of the new procedures to the conventional Discrete Fourier Transform method for Monte Carlo simulations utilizing known sinusoids buried in white noise, known sinusoids buried in human EEG noise and for a sample of visual evoked potential data. Both of the new methods produce substantially more accurate and less variable estimates of test sinusoid amplitude. For VEP recording, the EEG background noise level is reduced by 5-6 dB over that obtained with the DFT. The new methods also provide approximately 5 dB better SNR than the DFT for detection of sinusoids based on the Rayleigh statistic. The parametric modelling approach is particularly suited for the analysis of very short data records including cycle-by-cycle analysis of the SSEP.

Defining topological equivalences in protein structures by means of a dynamic programming algorithm

An automatic algorithm for defining topological equivalences in protein structures is presented. The algorithm is based on a dynamic programming technique and self-consistent scoring method. We have used it to align pairs of similar protein structures of several protein families and to identify recurrent structural domains in aspartic proteinase 2APR. Its ability to find suboptimal paths permits a thorough comparison of proteins at each level in the hierarchy of the protein structure: secondary structure, super-secondary structure, domain and entire globular structure. The algorithm has been extended to the structure alignment of ribonucleic acid and can be extended to the structure alignment of any linear polymer.

Molecular epidemiologic study of an outbreak of Salmonella typhimurium infection at a newborn nursery

Plasmid analysis, restriction endonuclease analysis, antimicrobial susceptibility testing, biotyping, phage typing and outer membrane protein electrophoresis were used to study an outbreak of Salmonella typhimurium infection at a newborn nursery. Seven out of the 12 neonates had positive blood cultures for S. typhimurium, and 2 of them died of severe sepsis. Thirty epidemic strains of S. typhimurium belonging to phage type 12 had the same plasmid profiles (98.0, 6.7 and 3.8 Kb) and identical restriction digest patterns (23.0, 20.4, 15.0, 9.6, 8.2, 7.4, 5.8, 4.3, 3.8, 2.0 and 1.8 Kb) which were different from those of the 2 non-epidemic strains. Laboratory data suggested that the source of the infection was the index patient's mother who had a slight diarrhea; the mode of transmission was most likely due to the transfer of organisms from infant to infant by the contaminated hands of nurses during milk feeding.

[The applicability of a new stable fluorescence reagent CGE (N) for TLC measurements and spectrofluorimetry]

A new stable fluorescent reagent, CGE (N), was designed and synthesized in our laboratory. This paper presents the results of using it to detect a compound having aminogroup. Glycine as an example was derived by using CGE (N), the best condition of derivatisation reaction was pH8, T 50 +/- 1 degree C, and time 3-5 h. Spread agent was CHCl3: CH3OH:CH3COOC2H5: iceHAc (1:3:5:1). Rf of glycine-CGE (N) was 0.45, of which fluorescent spectrum Em was 356nm (at Ex = 277nm). The correlation coefficient between the fluorescent scanning area and quantity was over 0.99, the linear relation retained for 24 h, the detection limit 0.24 microgram, and the linear range 0.24-19.2 micrograms. The data revealed that stability, sensitivity and reproducibility were good. These indicate that CGE(N) is a fine fluorescent reagent for compounds having primary amino-group and this method is reliable.

The Cdk-associated protein Cks1 functions both in G1 and G2 in Saccharomyces cerevisiae

The CKS1 gene of Saccharomyces cerevisiae encodes a small essential protein shown to interact genetically and physically with the Cdc28 protein kinase. To investigate the specific functions of the CKS1 gene product, conditional temperature-sensitive mutant alleles were generated. The mutations were found to impair the ability of cells to undergo both the G1/S-phase and G2/M-phase transitions of the cell cycle, as well as the ability to bud. Mutants were not defective, however, in their ability to activate Cdc28 kinase as assayed in vitro on the substrate histone H1. It is likely, therefore, that Cks1 mediates a more specialized function of the Cdc28 kinase such as its ability to form specific multimeric complexes or to localize properly in cellular compartments.

Phlebotomine sandflies of Kenya (Diptera: Psychodidae). I. The validity of Phlebotomus (Larroussius) elgonensis Ngoka, Madel and Mutinga

Sandflies collected in Kitum cave on the Kenyan side of Mount Elgon were identified as Phlebotomus (Larroussius) elgonensis Ngoka, Madel and Mutinga, a species synonymized with P. (L.) aculeatus Lewis, Minter and Ashford, by D. J. Lewis. A comparison of the flies from Kitum cave with P. aculeatus from Lake Elmentaita, Kenya, shows marked differences in the lengths of: (a) the spermathecal ducts of the female; (b) the style, coxite, genital pump and aedeagus of the male; and (c) the palpal segments of both sexes. Other notable differences are in the shape of the base of the spermathecal ducts; the position of spines on, and the shape of, the tip of the aedeagus; and the appearance of the pharyngeal armatures of both sexes. Phlebotomus elgonensis is redescribed and it is concluded that it is sufficiently different from P. aculeatus to deserve recognition as a valid species.

Effects of immunization with the p12 proteins of LP-BM5 defective and ecotropic viruses on development of MAIDS

Among murine leukemia viruses (MuLV) present in the LP-BM5 virus mixture, the agent etiologic for an acquired immunodeficiency syndrome (MAIDS) is replication defective, containing only a single open reading frame which includes all of gag. The Gag polyprotein encoded by the defective virus, termed BM5def, differs most in p12 from that of nonpathogenic ecotropic virus (BM5eco). As one approach to examining the role of p12 in disease, the ecotropic and defective virus forms of the protein, synthesized in bacteria, were used to immunize three strains of mice differing in their sensitivity to MAIDS. In each strain, both proteins elicited substantial antibody responses that were cross-reactive with either p12 and recognized the proteins as part of intact viral Gag polyproteins. Immunization with either p12 before infection with LP-BM5 viruses had no effect on the sensitivity or resistance of mice to MAIDS or on the extent of helper virus spread. The variant p12 of BM5def, when presented on its own, is thus not a crucial antigenic determinant of disease. Alternative mechanisms by which BM5def may contribute to MAIDS are discussed.

Retrovirus-induced lymphoproliferation as a model for developing diagnostic criteria for malignant lymphoma in mice

Several methods for evaluating lymphoproliferative lesions in mice were compared. The model systems included spontaneous lymphomas arising in CWD mice and NFS mice congenic for ecotropic murine leukemia virus (MuLV) induction loci and a series of transplants in mice with severe combined immunodeficiency disease mutation of cells derived from mice infected with LP-BM5 MuLV. Primary lymphomas and donor tissues and transplants were examined using histopathology, flow cytometry, and Southern blot analysis of DNA for rearrangements of immunoglobulin and T-cell receptor genes and for viral integrations. The use of flow cytometric analysis, to establish cell lineage and define population size, and DNA analysis, for cell lineage and clonality determination, allowed the identification of malignant lymphoproliferations. Histologic evaluation did not define clonal populations of particular lineage but did provide other indications of malignancy such as invasiveness and presence of a dominant morphologic cell type. Thus, the precision of diagnosis of mouse lymphomas can be considerably enhanced by augmenting histopathologic examination with antigenic and molecular characterizations that can define malignant populations.

Syncope in nasopharyngeal carcinoma: report of three cases and review of the literature

Syncope is an uncommon symptom in patients with nasopharyngeal carcinoma (NPC). Here we report three cases of NPC with syncope. One had bilateral neck masses, invasion of the skull base, and lower cranial nerve palsies. The other two presented with neck mass only. Repeated episodes of syncope were initially controlled by intravenous atropine followed by radiotherapy and/or chemotherapy. The large primary tumor with parapharyngeal space extension and neck lymph node involvement, the invasion of the skull base and the presence of lower cranial nerve palsies are the three important risk factors for developing syncope. This is probably mainly due to the mass compression of the carotid sinus or the glossopharyngeal nerve invasion. We therefore classified these 3 cases into carotid sinus syncope type, glossopharyngeal neuralgia type and parapharyngeal space lesions type. The prognosis is poor for cases of NPC with syncope because most patients have advanced or recurrent disease, however, atropine and radiotherapy with or without chemotherapy are effective for the symptomatic treatment of syncope from locally advanced NPC.

[Induction of micronucleus by organophosphorus pesticides both in vivo and in vitro]

A total of 22 organophosphorus pesticides (OPPs), including 8 ethyl-, 9 methyl-, and 5 other OPPs, were tested for mutagenicity in micronucleus assay system both in 615 mouse marrow cells in vivo with multi-intraperitoneal administrations and in cultured Chinese hamster lung (CHL) cells in vitro; and structure-mutagenicity relationship of OPPs was analyzed. Among the OPPs tested in vivo, 5 ethyl-(diazinon, chlorpyrifos, disulfoton, ethion, and parathion), and only 1 methyl-(dimethoate) were found mutagenic, while the other OPPs were negative. Six ethyl- (azinphos ethyl, chlorpyrifos, ethion, parathion, phosaione, and quinaphos), 8 methyl- (azinophos methyl, chlorpyrifos methyl, dichlorvos, dimethoate, fenitrothion, malathion, parathion methyl, and trimethyl phosphate), and 2 other OPPs (EII and MIA), however, induced micronucleus in CHL cells in vitro. The results indicated that most of the ethyl-OPPs tested showed the ability to induce micronucleus both in vivo and in vitro, and that most of the methyl-OPPs were positive only in vitro. The mechanism for the adversity of mutagenic activity in micronucleus assay in vivo and in vitro produced by different kinds of OPPs was also discussed.

Refined 1.6 A resolution crystal structure of the complex formed between porcine beta-trypsin and MCTI-A, a trypsin inhibitor of the squash family. Detailed comparison with bovine beta-trypsin and its complex

The crystal structure of the complex formed by porcine beta-trypsin with the MCTI-A inhibitor (Momordica charantia, Linn. Cucurbitaceae) has been determined at 1.6 A resolution using the molecular replacement method. The sequence of MCTI-A was determined by recognizing the electron density, and shows that MCTI-A is a member of the squash family of trypsin inhibitors. We report the first high-resolution structure of porcine beta-trypsin. Detailed comparisons have been made on the overall structure, solvent structure and active-site geometries between this complex and bovine beta-trypsin and its complexes. On the basis of our results, we discuss the interaction patterns between inhibitor and trypsin. Unlike other complex structures formed by bovine trypsin with inhibitors, no out-of-plane distortion around the inhibitor's scissible peptide was observed. The role of the trypsin catalytic triad is also discussed on the basis of this structure.

Widely tunable all-solid-state optical parametric oscillator for the visible and near infrared

An all-solid-state optical parametric oscillator (OPO) has been developed in which the signal and idler waves can be tuned over the ranges 455-665 and 760-1620 nm, respectively, with the potential for covering the entire range 420-2300 nm. The OPO uses a critical type I phase-matching geometry in lithium triborate and is pumped at 355 nm by frequency-tripled radiation from a diode-laser-pumped Nd:YAG laser. Oscillation thresholds (minimum 0.3 mJ), pump depletions (>35%), and linewidths of the OPO are reported.

[Experimental and clinical study on cryptosporidiasis. III. Ultrastructural observation on Cryptosporidium in immunosuppressed mice]

The ultrastructure of Cryptosporidium parvum, which parasitized on the surface of the intestine of the immunosuppressed mice, was studied by transmission electron microscopy. The parasite was enveloped by the parasitophorous vacuole developed from the host epithelial cell. An electron dense band was found at the attachment site between the Cryptosporidium and the host cell. At the attachment site, the cytoplasma membrane of Cryptosporidium appeared in the form of many membranous folds, and contacted closely with the plasma membrane of the epithelial cell. Rhoptry-like structure and small electron dense granules were found in the merozoite, but their effects on the development of Cryptosporidium are still unknown (Figs. 1-5).

No alpha-lactalbumin-like activity detected in a low molecular mass protein fraction of rat epididymal extract

The same low M(r) protein fraction of epididymal luminal fluid as that studied previously by Hamilton in 1981 was assayed for alpha-lactalbumin (alpha-lac) activity with bovine milk galactosyltransferase (GalTase) as the enzyme source and bovine serum albumin (BSA) to make the total protein concentrations of all the samples in each assay constant. No alpha-lac activity could be detected in this fraction. When glucose was used as an acceptor, radioactivity passing through the ion exchange column used to retain the remaining UDP-galactose did increase with the amount of the proteins of the low M(r) fraction, but this increase was observed not only for samples with an acceptor but also for samples without. The increased radioactive product co-migrated in high-voltage electrophoresis with galactose, not lactose. When GlcNAc was used as an acceptor, the situation was the same, and the increased radioactive product co-migrated with galactose, not LacNAc. No inhibition of bovine milk GalTase activity by the low M(r) proteins was observed. Addition of protein, either BSA or the low M(r) fraction of epididymal luminal fluid, to assay medium that contained no proteins other than GalTase enhanced the GalTase activity both in forming lactose in the presence of glucose and also LacNAc in the presence of GlcNAc. It appears that the earlier reports of alpha-lac-like activity in epididymal fluids and extracts may have been due to the presence of enzymes liberating free galactose from UDP-galactose and/or a stimulatory non-specific effect of the protein in the solutions on the lactose synthesis activity of the GalTase.

Protective effect of anisodamine on cultured bovine pulmonary endothelial cell injury induced by oxygen-free radicals

Anisodamine, a Chinese traditional medicine herb, has been used for treatment of adult respiratory distress syndrome effectively, but little is known about its mechanism. We attempted to investigate if anisodamine could protect bovine pulmonary endothelial cell injury induced by exogenous oxygen-free radicals that were generated by xanthine/xanthine oxidase or opsonized zymosan-stimulated polymorphonuclear leukocytes. Results showed that with the addition of xanthine/xanthine oxidase into cultured bovine pulmonary endothelial cells, production of malondialdehyde and release of lactate dehydrogenase in supernatant increased, and synthesis of prostacyclin decreased. Damaged cellular membranes were revealed by scanning electron microscopy. The same was true for the addition of opsonized zymosan-stimulated polymorphonuclear leukocytes. While treatment with anisodamine greatly attenuated all of the above-mentioned parameters, results showed that (1) cultured bovine pulmonary endothelial cells could be damaged by oxygen-free radicals, (2) anisodamine had a protective effect on this injury as effective as that of superoxide dismutase and catalase, and (3) the membrane-stable action might contribute to the mechanism of protective effect against this injury.

Chiral separation of nipecotic acid amides

1-Decyl-3-(N,N-diethylcarbamoyl)piperidine (1) and alpha,alpha'-bis[3-(N-benzyl-N-methylcarbamoyl)piperidinol]-p-xyle ne (2) represent mono-N-substituted and bis-N-substituted carbamoylpiperidines, or nipecotic acid amides, respectively. Initially, several attempts were made to resolve these compounds using beta-cyclodextrin, cellulose carbamate and Pirkle-type columns. However, the interactions of the stereoisomers of the two compounds with these stationary phases did not differ enough to permit satisfactory separations. Baseline resolution was achieved using an alpha 1-acid glycoprotein (AGP) chiral column. The mobile phase was phosphate buffer (pH 7.0). Tetrabutylammonium (TBA) was used as the cationic modifier and ethanol as the uncharged modifier. Circular dichroism was used to identify the enantiomers. Compound 1 was resolved into positive and negative enantiomers and 2 into positive and negative enantiomers and a meso diastereomer. The influence of pH, buffer ionic strength, cationic and uncharged modifier concentrations on retention, chiral selectivity and resolution were evaluated. Based on the results, it is suggested that both ionic and hydrophobic interactions may be responsible for retention and resolution.

Synthesis and cholinergic properties of N-aryl-2-[[[5-[(dimethylamino)methyl]-2-furanyl]methyl]thio]ethylamino analogs of ranitidine

A series of N-aryl-2-[[[5-[(dimethylamino)methyl]-2- furanyl]methyl]thio]ethylamino analogs of the H2-antagonist, ranitidine, was synthesized and the abilities of the compounds to alleviate the cholinergic deficit characteristic of Alzheimer's disease evaluated. The compounds were initially tested for their ability to inhibit human erythrocyte acetylcholinesterase activity in vitro. Selected compounds were further evaluated for butyrylcholinesterase inhibition, M1 and M2 cholinergic receptor binding, potentiation of ileal contractions, and the ability to elevate brain acetylcholine levels in mice. The analogs were compared to tetrahydroaminoacridine and to a recently reported series of bis-[[(dimethylamino)methyl]furans]. The N-aryl-2-[[[5-[(dimethylamino)methyl]-2- furanyl]methyl]thio]ethylamine derivatives were generally comparable to tetrahydroaminoacridine and the bis[[(dimethylamino)methyl]furans] in acetylcholinesterase inhibition, M1/M2 receptor binding, and the potentiation of ileal contractions, while being more potent inhibitors of acetylcholinesterase than butyrylcholinesterase. The 4-nitro-3-pyridazinyl analog, 26, was notable in demonstrating a potent and selective binding to the M2 receptor, with an M2 IC50/M1 IC50 of 0.060. Compounds in which the substituents on the dinitro-N-aryl moiety were relatively small were the best at inhibiting acetylcholinesterase in vitro. The N-aryl-2-[[[5-[(dimethylamino)methyl]-2- furanyl]methyl]thio]ethylamines in general, and those with small N-aryl substituents in particular, were superior to the bis[[(dimethylamino)methyl]furans] in elevating brain ACh levels in mice, probably due to enhanced distribution into the CNS. The 1,5-difluoro-2,4-dinitrophenyl analog, 8, resulted in the largest elevation in brain acetylcholine levels, affording a 53% increase at 88 mg/kg.

[Primary observation on antidotal effect of the Chinese drug mutong against fuzi]

Mutong can reduce Fuzi's toxicity markedly. This reducing effect is directly proportional to the dosage of Mutong within a certain range and the content of alkaloid in Fuzi drops clearly after Fuzi and Mutong are used in the same prescription.

All-solid-state optical parametric oscillator for the visible

An all-solid-state optical parametric oscillator (OPO) with signal and idler waves tunable over the ranges 481-457 and 1355-1590 nm, respectively, has been developed. Radiation at 1064 nm from a diode-laser-pumped Nd:AG laser (delivering 10-mJ Q-switched pulses of 18-ns duration at rates of 10-100 Hz) is frequency tripled at efficiencies near 30% and then used to pump the lithium triborate OPO, thus an all-solid-state configuration is realized. Oscillation thresholds (0.4 mJ), pump depletions (50%), external efficiencies (27%), and temperature-tuning rates (signal -0.11 nm/ degrees C, idler +0.87 nm/ degrees C) for the OPO are reported.

Synthesis and cholinergic properties of bis[[(dimethylamino)methyl]furanyl] analogues of ranitidine

The histaminergic H2 antagonist, ranitidine, has also been found to significantly inhibit acetylcholinesterase (AChE) in vitro. In an effort to develop novel, nonquaternary AChE inhibitors capable of penetrating into the CNS and alleviating the cholinergic deficit characteristic of Alzheimer's disease, a series of bis[[(dimethylamino)methyl]furanyl] analogues of ranitidine has been synthesized. All compounds were evaluated for human erythrocyte AChE inhibitory activity and compared to ranitidine, physostigmine, and tetrahydro-9-aminoacridine (THA). The most active AChE inhibitors were N,N'-disubstituted derivatives of 2-nitro-1,1-ethenediamine and 4,6-dinitro-1,3-benzenediamine, with compound 8 demonstrating activity greater than physostigmine. Deletion of the diaminonitroethene group in a series of alkyl and aryl bis-thioethers, yielded a number of slightly less active compounds, comparable in potency to THA. The 13 most active AChE inhibitors all demonstrated a more selective inhibition of AChE, as opposed to butyrylcholinesterase inhibition, than did THA. Compounds 3 and 22 were equally active to THA in potentiating rat ileal contractions. Binding studies demonstrated M1 and M2 cholinergic receptor affinities slightly greater than or equal to THA. Differential receptor binding studies showed compound 12 resembled THA in agonist/antagonist activity. Compounds 11-13 significantly elevated mouse brain acetylcholine levels, when administered at 80% of their approximate lethal doses, but were less active than THA or physostigmine.

Building protein backbones from C alpha coordinates

An automatic procedure for building polyalanine backbones from guiding alpha-carbon positions is presented. Polyalanine backbones are built based on the geometric restraints of angle N-C alpha-C and the knowledge of main-chain dihedral angle distributions. A building module constructs a list of polyalanine backbones that follow exactly the C alpha trace. Then a selection module selects one backbone with the largest portion of phi-psi pairs in favoured regions. Several test cases on C alpha coordinates from X-ray refined structures give acceptable results. Less than 10% of the peptide planes are incorrectly built, and the result is not sensitive to random shift up to 0.5 A of C alpha coordinates.

Amino acid sequencing of a trypsin inhibitor by refined 1.6 A X-ray crystal structure of its complex with porcine beta-trypsin

The stoichiometric complex formed between porcine beta-trypsin and the Momordica charantia, Linn. Cucurbitaceae trypsin inhibitor-A (MCTI-A) was crystallized and its X-ray crystal structure determined using molecular replacement method. The primary sequence and topology of the inhibitor was determined by recognizing the electron density and refined to a final R value of 0.167 (7.0-1.6 A) with RMS deviation of bond lengths from standard values 0.012 A. The sequence was compared with those obtained by other groups and was found to be similar to the squash proteinase inhibitor. Its spatial structure and the conformation of its primary binding segment from Cys-3I (P3) to Glu-7I (P3') which contains the reactive scissile bond Arg-5I C-Ile-6I N were also very similar with other squash family proteinase inhibitors.