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At least 415 records · Page 23Linked to original sources
PubMed2001

An integrated system to study multiply substituted human immunodeficiency virus type 1 reverse transcriptase.

We describe a gene system allowing the facile production of multiply substituted reverse transcriptases (RTs), the enzymatic characterization of these purified RTs, and the study of these mutations in the defined genetic background of the macrophagetropic, non-laboratory-adapted human immunodeficiency virus type 1 (HIV-1) AD8 strain. Thirteen unique silent restriction sites were introduced in the pol gene encoding HIV-1 RT, allowing easy introduction of mutations. To simplify genetic manipulation and generate p66/p51 heterodimers in Escherichia coli, a gene construct of the viral protease alone was optimized for expression from a separate vector carrying a p15A origin of replication. Active-site titration experiments using pre-steady-state kinetics showed that our system yields a higher proportion of active enzyme than that obtained by alternate methods. To facilitate phenotype/genotype correlations, the modified RT gene was designed to be easily reintroduced into a recombinant proviral AD8 HIV-1 DNA. Infectious viruses made from this vector were undistinguishable from wild-type AD8 HIV-1, an isolate able to infect peripheral blood mononuclear cells and macrophages. Thus, the pol gene can tolerate many silent mutations in the polymerase domain without affecting the functionality of the HIV-1 genome. The system was validated biochemically and virologically using the V75T substitution associated with stavudine resistance.

Amino Acid Substitution↗
PubMed2005

A site-directed integration system for the nonuniversal CUG(Ser) codon usage species Pichia farinosa by electroporation.

Halotolerant yeast, Pichia farinosa, is a valuable yeast strain in fermentation industry because it produces high yield of glycerol and xylitol, and can tolerate both contamination and high-density growth during fermentation. However, the lack of genetic manipulation tools makes it less popular as a gene engineering strain. Expression systems commonly used in other yeast systems, such as Saccharomyces cerevisiae and Pichia pastoris cannot be used in P. farinosa because it translates universal Leu codon CUG as Ser. Here we reported a modified expression vector and a transformation system with enhanced efficiency in P. farinosa. The results showed that cells of OD(600 )0.8-1.0 with DTT treatment can obtain high transformation efficiency. The optimized electroporation condition was 900 V, 25 microF, and 200 Omega. The DNA concentration did not influence the transformation. Our system provides the potential not only for applying P. farinosa as an industrial strain of gene engineering, but also for studying gene function in its native host.

Amino Acid Sequence↗
PubMed1990

Integrating systemic cue exposure with standard treatment in recovering drug dependent patients.

Repeated drug administration readily produces classically conditioned responses in animal and human experimental studies. The majority of patients applying for treatment of drug dependence show both autonomic and subjective responses when exposed to drug-related stimuli. These responses are presumed to have been conditioned during a period of active drug use, persist after traditional treatment for drug dependence, and may constitute one of several factors which predispose to relapse. Preliminary data are presented from a novel treatment approach which is designed to test whether drug-conditioned responses can be reduced or extinguished by systematic exposure to drug-related cues and whether such extinction improves the overall results of treatment.

Adult↗
PubMed2004

Overview and fundamentals of urologic robot-integrated systems.

Advances in technology have revolutionized urology. Minimally invasive tools now form the core of the urologist's armamentarium. Laparoscopic surgery has become the favored approach for treating many complicated urologic ailments. Surgical robots represent the next evolutionary step in the fruitful man-machine partnership. The introduction of robotic technology in urology changes how urologists learn, teach, plan, and operate. As technology evolves, robots not only will improve performance in minimally invasive procedures, but also enhance other procedures or enable new kinds of operations.

Equipment Design↗
PubMed2002

A low-noise flexible integrated system for recording and analysis of multiple electrical signals during sleep-wake states in rats.

A low-noise flexible system for the simultaneous recording and analysis of several electrical signals (EEG, ECG, EMG, and diaphragm EMG) from the same rat was constructed for studying changes in physiological functions during the sleep-wake cycle. The hardware in the system includes a multichannel amplifier, a video camera, a timer code generator, and a PC. A miniature buffer headstage with high-input impedance connected to a 6-channel amplifier was developed. All electrical activities devoid of 60 Hz interference could be consistently recorded by our low-cost amplifier with no shielding treatment. The analytical software was established in the LabVIEW environment and consisted of three major frames: temporal, spectral, and nonlinear analyses. These analytical tools demonstrated several distinct utilities. For example, the sleep-wake states could be successfully distinguished by combining temporal and spectral analyses. An obvious theta rhythm during rapid-eye-movement sleep (REMS) was recorded from parietal to occipital cortical areas but not from the frontal area. In addition, two types of sleep apnea with/without cardiac arrhythmias were observed under REMS condition. Moreover, the evoked potentials of the primary somatosensory cortex elicited by innocuous electrical pulses were modulated by vigilant states, especially under a slow-wave sleep state. These results show that our system delivers high-quality signals and is suitable for sleep investigations. The system can be easily expanded by combining other recording devices, like a plethysmograph. This compact system can also be easily modified and applied to other related physiological or pharmacological studies.

Animals↗