Alkali-Activated Fly Ash-Slag Cement Based Nuclear Waste Forms

This paper is based on the results of an in-progress research project on Alkali-Activated Cement System at MRL. The objective of this research is to establish the potential for large volume use of fly ash and slag as main components of the cement system. Alkali-activated Fly ash-slag Cement (AFC) was studied as a matrix for immobilization of nuclear waste. AFC is characterized by high early strength, high ultimate strength, low porosity, lower solubilities of the hydrates, and high resistance to chemical corrosion as well as to freezing and thawing. All these advanced properties are particularly favorable to the immobilization the nuclear wastes.

Collision-induced pulse shortening in a mode-locked linear-cavity NaCl color-center laser with an InGaAs/InP multiple-quantum-well saturable absorber

We report collision-induced reduction of pulse widths in a linear-cavity passively mode-locked NaCl color-center laser. Colliding-pulse operation reduced the pulse widths from 800 to 430 fs. Pulses collided in the InGaAs/InP multiple-quantum-well saturable absorber if the round-trip time from the absorber to the output coupler was less than 1.3 ns, which implies carrier recombination times of that order. Measurements of the gain experienced by two successive pulses indicated partial saturation of the NaCl gain medium.

DNA binding of CPF1 is required for optimal centromere function but not for maintaining methionine prototrophy in yeast

The centromere and promoter factor 1 (CPF1) binds specifically in vitro and in vivo to an octanucleotide (RTCACRTG). This sequence is found in the centromere DNA element I (CDEI) of yeast centromeres and upstream from a number of transcription units including MET25, GAL2 and TRP1. Inactivation of the CPF1 gene results in three phenotypes; slow growth, a partial loss of centromere function and methionine auxotrophy. These phenotypes correlate well with the known binding sites for CPF1 and have led to the suggestion that CPF1 functions as a kinetochore protein at centromeres and as a transcriptional activator at promoters such as MET25. By analysing transcription from the MET25, GAL2, and TRP1 genes in cpf1 strains, we demonstrate that CPF1 plays no direct role in their transcriptional regulation. Further evidence in support of this comes from the analysis of point mutations in the basic region of CPF1 that affect DNA binding. A strain expressing a non-DNA bound form of CPF1 is phenotypically Met+, shows normal growth rate but has sub-optimal centromere function. We conclude that a DNA-bound form of CPF1 is required for the kinetochore function but not for maintaining methionine prototrophy.

Rapid and sensitive nonradioactive detection of mutant K-ras genes via 'enriched' PCR amplification

We have developed a rapid and highly sensitive nonradioactive method for the detection of a mutant codon 12 human c-K-ras allele in the presence of as many as 10(4) copies of the wild type codon 12 allele. This sensitivity is achieved by selective polymerase chain reaction (PCR) amplification of mutant K-ras gene sequences employing a two stage procedure. The first stage entails the amplification of both K-ras mutant and wild type codon 12 sequences, followed by a selective restriction enzyme digestion of only wild type sequences. The second stage involves a subsequent amplification of undigested amplified fragments, enriched in mutant codon 12 sequences. These products are subject to restriction length polymorphism analysis for the detection of point mutations at codon 12. This technique is rapid, nonradioactive, and eliminates the need for either oligonucleotide hybridization or DNA sequencing. Variations of this selective amplification procedure may prove promising for the detection of specific point mutations in heterogenous cell populations.

Immunologic and structural characterization of the dominant 66- to 73-kDa antigens of Borrelia burgdorferi

The 66- to 73-kDa proteins of Borrelia burgdorferi are dominant immunogens and expressed in all strains of B. burgdorferi. The humoral response to these Ag occurs relatively early during the course of infection. Two-dimensional Western blot analysis of this group of Ag revealed them to consist of a tetrad of proteins with apparent molecular mass of 66, 68, 71, and 73 kDa. Furthermore, in this study we demonstrate the 66-kDa protein to be a potent inducer of lymphoproliferation in the patient immune to B. burgdorferi. Monospecific polyclonal antibodies and mAb demonstrate that each of these proteins was immunologically distinct. However, direct amino acid sequence of the 66- and 68-kDa Ag was almost identical and had a high level of sequence similarity to the GroEL heat-shock protein (Hsp60) of Escherichia coli and the 60-kDa immunodominant protein of Treponema pallidum. The amino terminal sequence of the 71- and 73-kDa proteins of B. burgdorferi was almost identical and these proteins had remarkable sequence similarity to the DnaK heat-shock protein of E. coli (Hsp70). It appears likely, therefore, that proteins related to the heat-shock family are potent immunogens of B. burgdorferi.

Immunologic and structural characterization of the dominant 66- to 73-kDa antigens of Borrelia burgdorferi

The 66- to 73-kDa proteins of Borrelia burgdorferi are dominant immunogens and expressed in all strains of B. burgdorferi. The humoral response to these Ag occurs relatively early during the course of infection. Two-dimensional Western blot analysis of this group of Ag revealed them to consist of a tetrad of proteins with apparent molecular mass of 66, 68, 71, and 73 kDa. Furthermore, in this study we demonstrate the 66-kDa protein to be a potent inducer of lymphoproliferation in the patient immune to B. burgdorferi. Monospecific polyclonal antibodies and mAb demonstrate that each of these proteins was immunologically distinct. However, direct amino acid sequence of the 66- and 68-kDa Ag was almost identical and had a high level of sequence similarity to the GroEL heat-shock protein (Hsp60) of Escherichia coli and the 60-kDa immunodominant protein of Treponema pallidum. The amino terminal sequence of the 71- and 73-kDa proteins of B. burgdorferi was almost identical and these proteins had remarkable sequence similarity to the DnaK heat-shock protein of E. coli (Hsp70). It appears likely, therefore, that proteins related to the heat-shock family are potent immunogens of B. burgdorferi.

Modulation of the cutaneous responsiveness of neurones in the primary somatosensory cortex during conditioned arm movements in the monkey

The present experiments were designed to investigate the neuronal mechanisms, at the level of the primary somatosensory cortex, which underlie the observation that somatosensory cortical potentials evoked by air puff stimuli directed at the forearm are decreased, in a nonspecific and widespread manner, during voluntary movements about the elbow. Unitary discharge was recorded from 131 cells receiving cutaneous input from the hairy skin of the forearm or hand (areas 3b and 1) of two monkeys trained to perform rapid movements of the contralateral arm (elbow flexion or extension). Evoked unitary responses to air puff stimuli applied to the centre of the cell's receptive field, at various delays before and after the onset of movement, were recorded. Movement produced a significant decrease in the short latency excitatory response to the air puff in 89% of the cells (117/131); the remaining 11% were not modulated by movement. This movement-related "gating" of cutaneous inputs occurred regardless of the response pattern of the cells to movement alone, being observed in 91% of the cells with no movement-related discharge, and 89% of those with movement-related discharge. The air puff responses of cells with inputs from the forearm and the dorsum of the hand were all similarly modulated by movement and the modulation was clearly present prior to the onset of movement (mean onset, -66 ms). Variation in the depth of modulation as a function of the direction of the movement, flexion or extension, was observed in only a very small proportion of the modulated units (16/117); most showed no relationship to direction. It is suggested that, in this experimental situation, much of the modulation appears to occur at a pre-cortical level since there was no relationship between the pattern of discharge of cells in relation to movement alone and the pattern of movement-related gating of their responses to the air puff. Effects which might be consistent with a cortical origin for the modulation were only infrequently observed. The present results are strikingly similar to those obtained using the evoked potential method, and thus support the hypothesis that in this task of rapid elbow movements, movement modulates the transmission of cutaneous signals from the hairy skin of the distal forelimb to primary somatosensory cortex in a nonspecific and widespread fashion.

Modulation of cutaneous cortical evoked potentials during isometric and isotonic contractions in the monkey

The effects of the direction of movement (flexion vs extension) and the nature of the motor task (isotonic vs isometric) on the modulation of sensory cortical evoked responses to cutaneous stimulation were investigated in one monkey. Sensory responses were assessed by measuring the magnitude of the short latency component of air puff-evoked potentials recorded intracortically in the arm representation of areas 3b and 1 in the primary somatosensory cortex. At most recording sites, it was found that the amplitude of the air puff-evoked potential was decreased in a non-specific manner by motor activity. Neither the timing nor the depth of the modulation were found to vary with either the direction or the type of contraction. The effects were widespread since inputs from practically the entire forelimb (hairy skin) were diminished during the motor tasks. These results thus show that the modulation was more closely linked to the central motor output than to the peripheral input generated by muscle force and/or limb displacement. It is suggested that signals originating from central motor structures, acting in a feedforward manner, play a major role in 'gating' cutaneous inputs during movement. It is further suggested that the centrally mediated effects are exerted via a final common pathway upon which the 'gating' signals converge.

[Comparative study of ventricular late potentials recorded on the body surface and epicardium in experimental myocardial infarction]

A noninvasive method for detecting ventricular late potentials (VLPs) was described. Signal averaging technique with high pass bidirectional digital filter was used to record signal-averaged electrocardiograms (SA-ECGs) on the body surface and epicardium. The SA-ECGs were performed with local ventricular electrograms (LVEs) simultaneously in order to compare the difference in records from the two methods. The LVEs have been recorded by epicardial composite electrodes. The signal averaging system was made in Fudan University (Shanghai) and Suzhou Medical College. Duration of filtered QRS (DQRS), duration of the under 40 microv low-amplitude signal (D40) and last 20 ms voltage of the filtered QRS (V20) were measured. VLPs were defined as the presence of two or more abnormal values. Experiments were performed on 20 anesthetized dogs with ligation of the left anterior descending artery. This study has demonstrated that: (1) DQRS greater than or equal to 60 ms, D40 greater than or equal to 20 ms, V20 less than or equal to 16 microv were considered as abnormal values. These values almost did not overlap with the values detected from normal epicardium and body surface; (2) VLPs were shown on the body surface in 12 of 18 dogs (66.6%) in 3 hours after coronary artery ligation, but decreasing to 42.8% (6/14) in 3-6 days later; (3) the fractionated ventricular electrograms were directly recorded on epicardium of the infarction region by composite electrodes and signal averaging system in late stage of myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

CPF1, a yeast protein which functions in centromeres and promoters

Centromeres and several promoters of Saccharomyces cerevisiae contain a highly conserved octanucleotide, RTCACRTG, called CDEI. Using biochemical, genetic and structural analyses, we show that the same protein binds in vivo to CDEI sites in centromeres and in promoters. This protein, called CPF1 for centromere promoter factor, binds DNA as a dimer. Inactivation of the gene is not lethal but leads to a partial loss of the centromere function and to a Met- phenotype. Changes of the chromatin structure due to inactivation of CPF1 are seen at centromeres and at several CDEI-carrying promoters (e.g. MET25, TRP1, GAL2). However promoter activities are affected in diverse ways making it presently difficult to describe a function for CPF1 in gene expression. The sequence of the cloned gene reveals in the carboxy-terminal part two potential amphipathic helices preceded by a positively charged stretch of amino acids very similar to the helix-loop-helix domains recently identified in factors controlling tissue specific transcription in higher eukaryotes. Carboxy-terminal truncations of CPF1 lacking this domain no longer bind to CDEI. The amino-terminal half of CPF1 carries two clusters of negatively charged amino acid residues. Surprisingly, deletions of these clusters still render cells Met+ and lead only to a marginal decrease in centromere activity.

Corrected sequence of the mannitol (mtl) operon in Escherichia coli

The previously published sequences of the operator-promoter region of the mannitol operon of Escherichia coli and of the mtlD gene have been found to contain a number of errors. The major conclusions reported previously were correct, but additionally it is now clear that a C-terminal portion of mannitol-1-phosphate dehydrogenase (the mtlD gene product) exhibits significant sequence identity with an amino-terminal region of human liver fructose-6-phosphate-2-kinase:fructose-2,6-bisphosphatase.

Direct detection and amplification of Helicobacter pylori ribosomal 16S gene segments from gastric endoscopic biopsies

Helicobacter pylori is an organism thought to play an important causative role in gastritis and peptic ulcer diseases. We have designed an RNA dot blot assay for the detection of H. pylori, using as probe a synthetic oligonucleotide complementary to its 16S rRNA. We have also used oligonucleotide primers, complementary to conserved sequences within bacterial ribosomal 16S genes, to amplify a H. pylori ribosomal 16S DNA fragment via the polymerase chain reaction (PCR). After determining the DNA sequence of this amplified H. pylori fragment, primers were designed for specific PCR amplification of H. pylori ribosomal 16S DNA sequences. Samples from clinical endoscopic biopsies were PCR amplified with universal 16S ribosomal primers to detect the presence of bacteria and with H. pylori-specific primers to uniquely detect H. pylori. Finally, by comparing the H. pylori-specific PCR assay to commonly used diagnostic tests, we demonstrate that the molecular technique of PCR amplification shows promising applications for the clinical detection of H. pylori.

[Effects of processing on volatile oil constituents in nutmeg and on the contents of myristicin]

This paper reports a GC analysis of the volatile oil contained in the nutmeg (Semen Myristicae) prepared by simmering wrapped in flour in hot purified talc, scalding in hot purified talc and stir-frying in smoking wheat bran. The experimental results showed that before and after processing the volatile oil compounds in nutmeg are the same and during processing no known compounds disappeared. The contents of the main volatile oil compounds in nutmeg changed, however, before and after processing, including the amounts of myristicin, one of the toxic compounds in nutmeg. It is suggested that the amounts of myristicin could be decreased notably under certain processing conditions.

Modulation of somatosensory evoked responses in the primary somatosensory cortex produced by intracortical microstimulation of the motor cortex in the monkey

Previous studies have shown that the amplitude of somatosensory evoked potentials is diminished prior to, and during, voluntary limb movement. The present study investigated the role of the motor cortex in mediating this movement-related modulation in three chronically prepared, awake monkeys by applying low intensity intracortical microstimulation (ICMS) to different sites within the area 4 representation of the arm. Air puff stimuli were applied to the contralateral arm or adjacent trunk at various delays following the ICMS. Somatosensory evoked potentials were recorded from the primary somatosensory cortex, areas 1 and 3b, with an intracortical microelectrode. The principal finding of this study was that very weak ICMS, itself producing at most a slight, localized, muscle twitch, produced a profound decrease in the magnitude of the short latency component of the somatosensory evoked potentials in the awake money. Higher intensities of ICMS (suprathreshold for eliciting electromyographic (EMG) activity in the "target" muscle, i.e. that muscle activated by area 4 stimulation) were more likely to decrease the evoked response and produced an even greater decrease. The modulation appeared to be, in part, central in origin since (i) it preceded the onset of EMG activity in 23% of experiments, (ii) direct stimulation of the muscle activated by ICMS, which mimicked the feedback associated with the small ICMS-induced twitch, was often ineffective and (iii) the modulation was observed in the absence of EMG activity. Peripheral feedback, however, may also make a contribution. The results also indicate that the efferent signals from the motor cortex can diminish responses in the somatosensory cortex evoked by cutaneous stimuli, in a manner related to the somatotopic order. The effects are organized so that the modulation is directed towards those neurones serving skin areas overlying, or distal to, the motor output.

Cross-antigenicity between the major surface proteins (ospA and ospB) and other proteins of Borrelia burgdorferi

Two of the major surface Ag of Borrelia burgdorferi, the 31-kDa OspA and 34-kDa OspB proteins, are encoded by a 49-kb plasmid. In this study, mAb and monospecific polyclonal antibodies were used to define cross-antigenicity of the OspA and OspB protein to each other and to other lower molecular mass proteins by Western blot analysis. Two mAb studied, 105.5 and 184.1, were directed predominantly against the 31-kDa OspA protein. However, each also reacted with other minor bands, though with different specificities. Using V8 protease digestion and cleavage by cyanogen bromide, we demonstrated that each mAb reacted to the 31-kDa protein differently. Monospecific polyclonal rabbit and human antibodies directed against the 34-, 31-, 22-, and 20-kDa proteins were eluted from blots and used to further corroborate the cross-reactivity among these Ag. Rabbit antibodies to the 31- and 22-kDa Ag gave remarkably similar peptide maps after V8 protease digestion of the 31-kDa OspA protein, as did mAb 184.1, suggesting that this mAb recognized an immunodominant epitope common to the 22- and 31-kDa proteins. It seems likely therefore that the humoral immune response to Borrelia surface Ag may be due to a limited number of cross-reactive epitopes on distinct, but related, gene products.

Cross-antigenicity between the major surface proteins (ospA and ospB) and other proteins of Borrelia burgdorferi

Two of the major surface Ag of Borrelia burgdorferi, the 31-kDa OspA and 34-kDa OspB proteins, are encoded by a 49-kb plasmid. In this study, mAb and monospecific polyclonal antibodies were used to define cross-antigenicity of the OspA and OspB protein to each other and to other lower molecular mass proteins by Western blot analysis. Two mAb studied, 105.5 and 184.1, were directed predominantly against the 31-kDa OspA protein. However, each also reacted with other minor bands, though with different specificities. Using V8 protease digestion and cleavage by cyanogen bromide, we demonstrated that each mAb reacted to the 31-kDa protein differently. Monospecific polyclonal rabbit and human antibodies directed against the 34-, 31-, 22-, and 20-kDa proteins were eluted from blots and used to further corroborate the cross-reactivity among these Ag. Rabbit antibodies to the 31- and 22-kDa Ag gave remarkably similar peptide maps after V8 protease digestion of the 31-kDa OspA protein, as did mAb 184.1, suggesting that this mAb recognized an immunodominant epitope common to the 22- and 31-kDa proteins. It seems likely therefore that the humoral immune response to Borrelia surface Ag may be due to a limited number of cross-reactive epitopes on distinct, but related, gene products.

Biochemical and immunological characterization of the surface proteins of Borrelia burgdorferi

The immunodominant proteins and glycoproteins of Borrelia burgdorferi were analyzed by one-dimensional (1D) and 2D gel electrophoresis. More than 100 polypeptide species could be detected on silver-stained 2D gels. Separation of sonic extracts of the organism by differential centrifugation (100,000 X g) revealed several of the major proteins to reside predominantly within the pellet fraction. The antigenicity of the individual polypeptides was determined by Western (immuno-) blot analysis with sera from humans with chronic Lyme disease and from rabbits immunized with B. burgdorferi. Surface proteins of viable B. burgdorferi labeled with 125I or long-arm hydroxysuccinimide biotin were identified by gel analyses. Thirteen major surface proteins were apparent, including the highly immunogenic 41-kilodalton (kDa) endoflagellar antigen. Two of these proteins, with molecular masses of 22 and 41 kDa, were further characterized by electroblotting and microsequencing their amino termini. Significant (35%) homology between the first 20 amino acids of the 22-kDa protein and the deduced amino acid sequence of the 31-kDa (outer surface protein A) protein of B. burgdorferi may indicate that these proteins are processed similarly or are part of a gene family expressed at the surface of the organism. In addition, highly significant (88%) homology was found between the first nine amino acids of the 41-kDa protein of B. burgdorferi and the 33-kDa endoflagellar protein of Treponema pallidum, after which the sequences diverge. This observation provides in part a structural basis for the observed cross-reactivity between the two organisms and suggests alternative approaches to the development of specific immunodiagnostics.

Rapid detection of ras oncogenes in human tumors: applications to colon, esophageal, and gastric cancer

We have developed a rapid, nonradioactive large scale method for the detection of ras oncogenes in human tumors. DNA is amplified by the polymerase chain reaction (PCR), and then digested with specific restriction enzymes to detect either endogenous or primer-mediated Restriction Fragment Length Polymorphisms (RFLPs). We report here that three of 15 colon tumors tested contain K-ras codon 12 aspartic acid mutations and one, along with the HCT 116 colon carcinoma cell line, contains a K-ras codon 13 aspartic acid mutation. On the other hand, we did not detect H- or K-ras codon 12 mutations or the K-ras codon 13 aspartic acid mutation in 25 esophageal and 27 gastric cardia tumors isolated from patients in Lin-xing County, China. By incorporating nucleotide substitutions in PCR primers, this method can be applied towards the rapid, non-radioactive screening of virtually any genetic disease caused by known point mutations.