Biomedical subjects

J Puryear

Publications and source records attributed to J Puryear.

5 recordsLinked to original sources

PubMed1996

Cloning of a cDNA for a chitinase homologue which lacks chitin-binding sites and is down-regulated by water stress and wounding.

A cDNA clone (pLP6) of a gene which is repressed under water deficit was isolated from a loblolly pine (Pinus taeda L.) cDNA library and characterized. The predicted polypeptide encoded by pLP6 bears strong resemblance to a number of Class I chitinases. However, LP6 lacks most of the amino-terminal and, consequently the signal peptide, cysteine-rich chitin-binding domain and glycine/proline-rich "hinge' region, diagnostic of Class I chitinases, are absent. Although the cDNA is similar in size to its mRNA, the long open reading frame encoding the LP6 protein commences halfway through the mRNA, implying a 5'-untranslated region of over 700 nucleotides. Subfragments from the 5' end of pLP6 hybridize to the same mRNA as do probes consisting of the entire cDNA. Reverse transcription(RT)-PCR experiments confirm that the cDNA derives from a single mRNA molecule. Analysis of the 5'-UTR revealed six upstream open reading frames and four inverted repeat structures. Expression of the pLP6 gene is repressed by water deficit stress and wounding. Possible functions and origin of this gene are discussed.

Amino Acid Sequence↗

PubMed1994

How to structure clinical practice guidelines for continuous quality improvement?

The purpose of this study was to evaluate the relevance of available practice guidelines to clinical quality improvement programs. A sample of 19 guidelines was evaluated in four prominent primary care areas. Two research assistants independently coded the clinical conditions and recommended/not recommended procedures abstracted from the guidelines (Cohen's kappa .67 and .50, respectively). An average of 35.1 (+/- 25.8) medical conditions and 48.4 (+/- 41.5) clinical procedures were defined by the guidelines. Most conditions were defined by using ICD-9-CM, age/sex group, or therapy, but 29% of definitions included symptoms which are not coded routinely. CPT codes alone were unable to identify most procedures. AHCPR guidelines mentioned significantly more procedures (p < .001) and fewer symptoms (p < .001) per clinical condition than other guidelines. The difficulty of finding codes for conditions and procedures, the high rate of non-codable items, and the lack of recommended measures limit the applicability of published clinical practice guidelines to continuous quality improvement programs.

Age Factors↗

PubMed1991

Abnormal right heart filling after cardiac surgery: time course and mechanisms.

OBJECTIVE: To study the time course and underlying mechanisms of right heart filling after cardiac surgery. DESIGN: A prospective observational study of adult patients undergoing cardiac surgery. SETTING: Echocardiography laboratory of the Stanford University Medical Center. PATIENTS: Twenty six patients (mean age 54.9) undergoing cardiac surgery were studied before and two days, one week, six weeks, and six months after cardiac surgery. MAIN OUTCOME MEASURES: Flow in the hepatic veins and superior vena cava, tricuspid and mitral annulus motion, signs of tricuspid regurgitation, and right ventricular size were assessed by echocardiography. RESULTS: Right heart filling, expressed as the ratio of systolic to diastolic forward flow Doppler velocity integrals in the superior vena cava and by tricuspid annulus motion, decreased in parallel from before surgery baseline values of 3.5 (SD 3.1) and 21.9 (3.4) mm, respectively to 0.2 (0.1) and 8.1 (2.3) mm two days after operation. A gradual increase towards baseline values was noted after six months, to 1.4 (1.3) and 15.1 (2.3) mm respectively; however, these values were still significantly less than those before operation. Similar changes were seen in the hepatic venous flow pattern. The decrease in total tricuspid annulus motion was most pronounced in its lateral segment and the atrial component of the tricuspid annulus motion showed similar changes. CONCLUSIONS: The pronounced decrease in tricuspid annulus motion during the early postoperative period suggests right atrial and right ventricular dysfunction as mechanisms responsible for the early changes seen. The progressive return to a normal venous filling pattern and the partial recovery of annular motion six months after operation further support the influence of the above mechanisms, as well as their resolution with time. The persistent flow abnormalities and compromised motion of the free aspects of the tricuspid annulus, however, suggest long term tethering of the right heart wall.

Adult↗

PubMedDate not supplied

Tricuspid annular motion.

Triscupid annular motion is related to right ventricular systolic function in the same way mitral annulus motion is related to left ventricular function. Tricuspid annular excursion reflects the longitudinal motion of the right ventricle, and the systolic descent of the anulus correlates with systolic venous inflow to the right atrium. However, it has not been shown clearly how to reproducibly quantify this motion. Therefore we describe a method to measure triscuspid annular motion using two-dimensional oriented M-mode echocardiography from the apical view. We studied a group of 10 normal subjects (mean age, 28.7 years; range, 25 to 38 years) and a group of 29 patients (mean age, 57.2 years; range, 20 to 84 years) with disease of the left side of the heart but no evidence of involvement of the right side of the heart. In each subject, tricuspid and mitral annular motion were measured respectively at their lateral, septal or medial, anterior, and posterior margin points. The total tricuspid annular motion for normal subjects was, as follows: lateral, 24.9 +/- 3.5 mm; medial, 20.1 +/- 2.5 mm; anterior, 21.6 +/- 3.8 mm; and posterior, 22.3 +/- 2.3 mm. Interobserver and intraobserver variability was low, with a coefficient of variance for the different annular points ranging from 6.19% to 11.56% between observers and from 4.10% to 7.26% within observer. We conclude that it is possible to measure tricuspid annular motion with this method in a reproducible way and to use it as a diagnostic tool in evaluating function of the right side of the heart.

Adult↗

PubMedDate not supplied

Echocardiographic contrast increases the yield for right ventricular pressure measurement by Doppler echocardiography.

Doppler ultrasound has become accepted as a measurement of right ventricular systolic pressure in patients who have a quantifiable signal from tricuspid regurgitation. This study evaluated the use of intravenous injection of saline solution for echo contrast to increase the percentage of quantifiable tricuspid regurgitant signals in patients who have any detectable tricuspid regurgitation at baseline. Patients underwent a standard Doppler evaluation, followed by a contrast study with the injection of 4 to 6 ml of agitated saline solution into a brachial vein. Baseline and contrast tricuspid regurgitant signals were assessed for quality, quantifiability, and reproducibility of the derived pressures by three observers on two occasions. The average absolute pairwise deviation among the three observers was low: 1.6 mm Hg (standard deviation, 1.4 mm Hg). The intraobserver mean discrepancy was low: 0.03 mm Hg (standard deviation, 2.33 mm Hg). Patients who did not have tricuspid regurgitation (n = 10) failed to develop such regurgitation during contrast injection. Only eight of 40 patients (20%) who had trace or mild tricuspid regurgitation had quantifiable baseline signals, but 34 patients (85%) had quantifiable signals with contrast injection. All patients who had mild to moderate, moderate, or severe tricuspid regurgitation (n = 10) had quantifiable signals before contrast injection. Of all patients who had any tricuspid regurgitation, 88% had quantifiable signals with contrast injection. Echo contrast was shown to improve the yield of quantifiable signals in patients who had trace and mild tricuspid.

Adult↗