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Biomedical subjects

R A Pierce

Publications and source records attributed to R A Pierce.

At least 55 records · Page 3Linked to original sources
PubMed1991

Changes in aortic levels of tropoelastin mRNA following treatment of rats with the antihypertensive drugs captopril and hydralazine.

This manuscript describes changes in the steady state levels of aortic tropoelastin mRNA in spontaneously hypertensive rats (SHR) and normotensive controls (WKY) following treatment with two antihypertensive drugs. Three-week-old WKY and SHR rats were treated with hydralazine (15 mg/kg/day) or captopril (25 mg/kg/day). Tail artery blood pressure was monitored twice weekly. Both drugs prevented the development of hypertension in the SHR rat. At 6 weeks of age, total aortic RNA was extracted and the steady state levels of mRNAs coding for tropoelastin and pro alpha 1 (III) collagen were determined by slot blot hybridization analysis using radiolabeled tropoelastin and pro alpha 1 (III) collagen cDNA clones. Hydralazine treatment resulted in a threefold increase in tropoelastin mRNA levels in both the SHR and the WKY animals (P less than 0.01). Captopril-treated SHR animals demonstrated a similar significant increase. In contrast, no differences in pro alpha 1 (III) collagen mRNA levels were observed in the aorta of SHR or WKY rats following treatment with either captopril or hydralazine. These data suggest that antihypertensive agents can act specifically to directly induce tropoelastin mRNA levels in large arteries and thus may induce vascular remodeling independent of an increase in blood pressure.

Aging↗
PubMed1991

Alternative splicing of rat tropoelastin mRNA is tissue-specific and developmentally regulated.

Sequence analysis of cDNA clones coding for rat tropoelastin previously has identified two variants that potentially corresponded to alternatively spliced tropoelastin mRNAs (Pierce et al., 1990). We have now used S1 nuclease protection analysis of total RNA from aorta, skin and lungs of 10-day and 6-week old rats to localize all sites of alternative splicing in the tropoelastin mRNA and to examine tissue-specific and developmental regulation of the use of these sites. This analysis revealed multiple sites of alternative splicing involving rat tropoelastin coding sequences corresponding to exons 12 through 15 of the bovine tropoelastin gene and a single site of alternative splicing at sequences corresponding to exon 33. Messenger RNAs from all three tissues at both developmental stages were alternatively spliced at the same sites; there was no evidence for the use of an alternative splice site unique to a particular tissue or developmental stage. However, both tissue-specific and developmentally regulated differences were apparent in the proportion of rat tropoelastin mRNA alternatively spliced at exon 33. Tropoelastin mRNA from the aorta and lungs of neonatal rats was alternatively spliced at exon 33 ten time more frequently than tropoelastin mRNA from skin. Between 10 days and 6 weeks of development, the use of this site of alternative splicing decreased by twenty-fold in RNA from skin, ten-fold in RNA from lungs and two-fold in RNA from aorta. In contrast, alternative splicing at exons 12 through 15 occurred in a small percentage of the mRNA and use of these sites exhibited minimal tissue-specific differences or developmental regulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1991

Mammalian tropoelastin: multiple domains of the protein define an evolutionarily divergent amino acid sequence.

We have recently derived the complete amino acid sequence of rat tropoelastin from a series of overlapping cDNA clones. Comparison of this protein sequence to bovine and human tropoelastin has revealed significant differences in the rates of evolutionary divergence of the various domains of tropoelastin. The overall rate of divergence of the hydrophobic domains of tropoelastin was twice as fast as the cross-link domains of the protein. Certain hydrophobic domains, however, are as conserved as cross-link regions, particularly the hydrophobic sequence coded for by exon 33, the only exon subject to alternate usage in all three mammalian species and the most conserved domain in rat, bovine and human tropoelastin. This conservation of sequence strongly suggests a more complex function of the hydrophobic region encoded by exon 33, beyond the elastic recoil characteristic of all hydrophobic domains of tropoelastin. A comparison of average rates of divergence of hydrophobic and cross-link domains of tropoelastin to functionally-defined domains of other structural proteins, such as collagen, has also revealed that overall, tropoelastin is a highly divergent amino acid sequence, comparable to proteins such as globin and the fibrino-peptides.

Amino Acid Sequence↗
PubMed1991

Desmoplasia in benign and malignant breast disease is characterized by alterations in level of mRNAs coding for types I and III procollagen.

Desmoplasia, the formation of excessive connective tissue surrounding some neoplasms, is a well documented, but incompletely understood phenomenon. To characterize the fibrotic response in benign breast conditions and malignancy, we examined the steady state levels of mRNA coding for types I and III procollagen in mild fibrocystic changes, in fibroadenoma, and in infiltrating ductal carcinoma. The results indicate that in mild fibrocystic change there is a relative increase in type III procollagen mRNA. In contrast, fibroadenoma and carcinoma are characterized by increased levels of type I procollagen mRNA.

Adult↗
PubMed1990

Heterogeneity of rat tropoelastin mRNA revealed by cDNA cloning.

A lambda gt11 library constructed from poly(A+) RNA isolated from aortic tissue of neonatal rats was screened for rat tropoelastin cDNAs. The first screen, utilizing a human tropoelastin cDNA clone, provided rat tropoelastin cDNAs spanning 2.3 kb of carboxy-terminal coding sequence and extended into the 3'-untranslated region. A subsequent screen using a 5' rat tropoelastin cDNA clone yielded clones extending into the amino-terminal signal sequence coding region. Sequence analysis of these clones has provided the complete derived amino acid sequence of rat tropoelastin and allowed alignment and comparison with published bovine cDNA sequence. While the overall structure of rat tropoelastin is similar to bovine sequence, numerous substitutions, deletions, and insertions demonstrated considerable heterogeneity between species. In particular, the pentapeptide repeat VPGVG, characteristic of all tropoelastins analyzed to date, is replaced in rat tropoelastin by a repeating pentapeptide, IPGVG. The hexapeptide repeat VGVAPG, the bovine elastin receptor binding peptide, is not encoded by rat tropoelastin cDNAs. Variations in coding sequence between rat tropoelastin cDNA clones were also found which may represent mRNA heterogeneity produced by alternative splicing of the rat tropoelastin pre-mRNA.

Amino Acid Sequence↗
PubMed1990

Collagen and elastin metabolism in hypertensive pulmonary arteries of rats.

We evaluated the processes controlling the accumulation of collagen and elastin in main pulmonary arteries of rats during an episode of hypoxic pulmonary hypertension. Explant cultures of main pulmonary arteries were incubated with [3H]proline to measure collagen and protein synthesis and percent collagen synthesis. Elastin synthesis was measured by [14C]valine incorporation into insoluble elastin. Relative collagen synthesis increased twofold (from 1.1 +/- 0.2 x 10(3) to 2.0 +/- 1.0 x 10(3) disintegrations per minute [14C]hydroxyproline/vessel/hr/mg protein), relative collagen synthesis doubled (from 2% to 4-5% of total protein synthesis), and elastin synthesis increased ninefold (from 0.4 +/- 0.2 x 10(4) to 3.6 +/- 0.6 x 10(4) dpm [14C]valine/vessel/hr/mg protein) in early hypertension. The level of pro alpha l(I) collagen RNA paralleled the relative collagen synthetic rate during the study period. Within 7 days of recovery from hypoxia, collagen and elastin contents were normal. We conclude that collagen and elastin in main pulmonary arteries are synthesized rapidly during an episode of hypoxic pulmonary hypertension and that collagen and elastin are rapidly removed from the hypertensive vessel during normoxic recovery.

Actins↗
PubMed1990

Outpatient pharmacy redesign to improve work flow, waiting time, and patient satisfaction.

An outpatient pharmacy redesign in which a pharmacist located outside the dispensing area speaks with each patient before the prescription is processed is described, and the effect of patients' waiting time and satisfaction is reported. Adoption of an open pharmacy plan at a Veterans Administration outpatient pharmacy allows patients to present their prescriptions to pharmacists in consultation booths equipped with computer terminals. The pharmacist promptly identifies and resolves any problem associated with a prescription or medication profile. The prescription then enters the dispensing work area, which was also redesigned to improve efficiency; patients now pick up their medications at a window on the opposite end of the dispensing area from where the pharmacist initially receives the prescription. Workload data and waiting times before and after implementation of the open pharmacy showed that prescriptions could be processed more quickly under the new system; average waiting times decreased from more than one hour to 30 minutes. Interviews of randomly selected patients indicated that the reduced waiting times led to increased patient satisfaction. The open pharmacy design appeared to improve work flow and to improve patient satisfaction by decreasing waiting times.

Consumer Behavior↗
PubMed1989

The effect of viable omentum on early bile leakage and healing of liver lacerations.

In order to determine if omental tissue accelerates the healing of liver lacerations, simulated bile leakage and collagen biosynthesis were studied in 53 rabbits. After creating a standardized complex liver laceration, hemostasis was obtained by vessel ligation and electrocoagulation. The wound was either left open (OP) or viable omentum sutured to its base (OM). Simulated bile leakage was noted in all of eight animals (four OM, four OP) studied on day of injury. None of 18 OM and two of 17 OP animals demonstrated extravasation of dye from the wound on the second and third postinjury day (N.S.). The ratio of mRNA for alpha 1(I) procollagen/actin, used as an indicator of wound healing, was 56.3 +/- 7.8 for OM and 50.6 +/- 12.1 for OP at the wound edge, and 63.5 +/- 18.6 and 69.2 +/- 7.5, respectively, for RNA isolated from the scar (N.S.). For alpha 1(III) procollagen mRNA, the ratio was 23.9 +/- 3.5 for OM and 22.4 +/- 8.3 for OP at the wound edge, and 32.4 +/- 6.5 and 31.8 +/- 7.9, respectively, for RNA isolated from the scar (N.S.). There was no difference in the scar hydroxyproline content between the two repair methods. In this model of hepatic injury and repair, bile leakage was minimal by the second postinjury day with both repair methods. Placing the omentum in liver lacerations did not contribute to accelerated wound healing as measured by simulated bile leakage and collagen biosynthesis.

Animals↗
PubMed1988

Rat tropoelastin is synthesized from a 3.5-kilobase mRNA.

A lambda gt11 cDNA library was constructed from poly(A+) RNA isolated from aortic tissue of neonatal rats and screened with a human tropoelastin cDNA clone. DNA sequence analysis of several overlapping rat clones confirmed the presence of DNA sequences coding for murine tropoelastin and DNA sequences coding for the 3'-untranslated region of the rat tropoelastin mRNA. Northern blot analysis of total RNA from aortic tissue of neonatal rats using oligonucleotide probes derived from these rat tropoelastin cDNAs demonstrated the presence of a 3.5-kilobase tropoelastin mRNA. The size of this rat tropoelastin mRNA agrees with previous reports for the size of the mRNA coding for tropoelastin in tissue from several vertebrate species but contrasts with several reports suggesting the presence of a higher molecular weight mRNA species responsible for the synthesis of tropoelastin in rodent tissue.

Animals↗
PubMed1988

Increased elastin mRNA levels associated with surgically induced intimal injury.

Quantitative levels of mRNAs coding for elastin, types I and III procollagen and gamma-actin were measured in porcine vascular material following balloon catheterization. A balloon catheter was introduced into the thoracic aorta and jugular vein of 3-6 week old pigs; following distention and six days of postoperative recovery, tissue samples were obtained for histopathology, electron microscopy, RNA extraction and mRNA quantitation. Using a series of mammalian cDNA clones and the procedure of slot blot hybridization, we have shown that elastin and types I and III procollagen mRNA levels rose significantly during the postoperative period following vascular distention. The increase correlated with an increase in the cell mass present in both the venous and arterial intimal layers. Changes in gamma-actin mRNA levels were also associated with this rapid proliferative response but in arterial tissue only.

Actins↗
PubMed1987

Increased procollagen mRNA levels in carbon tetrachloride-induced liver fibrosis in rats.

Carbon tetrachloride-induced liver damage is a well-characterized experimental model for studying liver fibrosis. We used this model to examine alpha 1(I), alpha 1(III), and alpha 1(IV) procollagen mRNA levels during the development of liver fibrosis. Rats were given 0.5 ml of carbon tetrachloride/kg of body weight for 1-6 weeks. The liver tissue was assayed for collagen content by measuring total hydroxyproline content. Specific increases in procollagen mRNAs were assayed by slot blot hybridization. There was a significant increase in hydroxyproline content of liver tissue following 3 weeks of carbon tetrachloride treatment. The increase in tissue collagen content correlated with an increase in alpha 1(I) procollagen mRNA levels. At 5 and 6 weeks of treatment, there was an increase in alpha 1(III) procollagen mRNA levels. alpha 1(IV) procollagen levels increased slightly with five injections of carbon tetrachloride treatment. These results suggest that specific increases in procollagen mRNAs in liver fibrosis parallel, but do not precede, increases in tissue collagen content.

Animals↗
PubMed1981

The affinity of platelets for the subendothelium.

It is known that platelets adhere to subendothelial tissues, but it is not clear as to whether this results in thrombus formation. To study this question, 94 arterial specimens in dogs were randomly treated, either by balloon stripping which exposed the subendothelium (Group I) or by endarterectomy, which exposed the media (Group II). Platelets tagged with 51Cr were injected into some of the animals and the degree of adherence to the vessel wall measured. In the rest, the thrombosis rate was measured at 48 hours. It was shown that the platelets tend not to adhere to the subendothelium in great numbers. The thrombosis rates were 8.6 per cent in Group I compared to 47.8 per cent in Group II. The conclusion drawn from these results was that the subendothelium was antithrombogenic and that this layer should be preserved at vascular anastomoses to discourage platelet adherence and thrombosis.

Animals↗