Biomedical subjects

I Chien

Publications and source records attributed to I Chien.

3 recordsLinked to original sources

PubMed2003

Spinal process landmark as a predicting factor for difficult epidural block: a prospective study in Taiwanese patients.

Although epidural anesthesia is a common practice in neuraxial blockade, difficult access to the epidural space is a frequent problem in operating theaters. We designed this study of epidural blocks to determine if the spinal landmark grading system is valuable in predicting a difficult epidural block. Before the epidural block, we collected the following data: demographics, body habitus (normal, thin, obese, pregnant), spinal anatomy (normal, deformed), spinal level (lumbar, thoracic), and spinal landmark grade (grade 1: spinous processes visible; grade 2: spinous processes not seen but easily palpated; grade 3: spinous processes not seen and not palpated but the interval between them is palpated as a low landmark under the thumb; grade 4: other). We performed all 848 epidural blocks initially using a midline approach and an 18-gauge Touhy needle. We evaluated the technical difficulty of the epidural block using three methods: whether the epidural block was accomplished at the spinal level (first-level success); the total number of attempts at skin puncture (attempts-S); and total number of attempts to change ligament puncture direction (attempts-L) required to complete the epidural block. Of all examined factors, spinal landmark grade correlated best with technical difficulty as measured by all three methods. Deformed spinal anatomy and body habitus both correlated with difficulty, merely from the total numbers of attempts (attempts-S and attempts-L). Thoracic epidurals were more difficult than lumbar epidurals by all three measures of difficulty. We concluded that this spinal landmark grading system is valuable in predicting a difficult epidural block and advocate its use as a predictor by anesthesiologists.

Adolescent↗

PubMed1982

The metabolic fate of independently initiated VSV mRNA transcripts.

The kinetics of synthesis and the metabolic stability of uncapped vesicular stomatitis virus (VSV) mRNA transcripts have been studied using techniques which clearly differentiate them from other RNA species. The triphosphate-initiating mRNA transcripts accumulate for at least 5 h during a typical in vitro transcription reaction. The great majority of these transcripts are smaller than a functional message and have been released from the template-transcriptase complex. Label that accumulates in them is stable and is not detectably diminished after a 1 h chase with unlabelled precursor. These kinetic properties are not these expected for active intermediates in mRNA synthesis and suggest that the uncapped transcripts are products of aborted transcription that accumulate during the transcriptive process. However, we cannot rule out that a small subset of these transcripts may be elongated into mature mRNA. Initiation of transcription at internal positions along the VSV genome is both frequent (one-half to one-sixth as frequent as initiations at the leader RNA gene) and site-specific (occurring only at the beginning of cistrons). The relevance of these results to the models for VSV transcription is discussed.

Kinetics↗

PubMed1980

Defective interfering particle generated by internal deletion of the vesicular stomatitis virus genome.

The genome structure of the long, truncated defective interfering particle derived from the heat-resistant strain of vesicular stomatitis virus has been examined. Stocks of this defective interfering particle are shown to contain several different species having information primarily from the 3' half of the vesicular stomatitis virus genome; the proportions of these components vary depending on the passage history of the stock. The two most abundant types have been identified and characterized. One has complementary 5' and 3' termini and consequently appears as a circular molecule when examined by electron microscopy. The other cannot circularize and remains linear. The circular forms are consistently 8 to 10% longer than the linear molecules. Rapid sequencing analyses reveal that both forms retain the 5' parental viral terminal sequence, but only the linear form retains the parental 3'-terminal sequence which is the complement of the 5' end. Hybridization experiments and electron microscopic analyses indicate that the linear form has retained 320 to 350 nucleotides of the 5' parental sequence and was probably generated by an internal deletion of the vesicular stomatitis virus genome.

Base Sequence↗