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Biomedical subjects

G Pearce

Publications and source records attributed to G Pearce.

At least 19 recordsLinked to original sources
PubMed1994

Overexpression of the prosystemin gene in transgenic tomato plants generates a systemic signal that constitutively induces proteinase inhibitor synthesis.

Tomato plants (Lycopersicon esculentum, var. Better Boy) were stably transformed with a gene consisting of the open reading frame of a prosystemin cDNA under the regulation of the cauliflower mosaic virus 35S promoter. The leaves of the transgenic plants constitutively produced proteinase inhibitor I and II proteins, which accumulated over time to levels exceeding 1 mg/g of dry leaf weight. This phenotype contrasts with that of untransformed plants, which produce proteinase inhibitor proteins in leaves only in response to wounding or chemical inducers. The transgenic plants were also stunted, although they appeared normal in all other respects. Grafting the upper half (scion) of an untransformed tomato plant onto the lower half (root stock) of a tomato plant expressing the prosystemin transgene resulted in the constitutive expression of proteinase inhibitor proteins in the leaves of both the transformed root stock and the untransformed scion, demonstrating that expression of the prosystemin transgene generates a mobile wound signal. These results show that systemic signal propagation in the transgenic plants does not require wounding, and they support the proposed role of systemin as the mobile wound signal.

Agrobacterium tumefaciens↗
PubMed1994

Polypeptide signalling for plant defence genes.

The synthesis of proteinase inhibitor proteins in response to wounding is a defensive response against pest and pathogen attacks. Wounding of leaves results in the release of a mobile wound signal which induces proteinase inhibitor synthesis throughout the plant. The signal transduction pathway regulating this response is not fully understood, but several compounds have been identified which are capable of inducing proteinase inhibitor synthesis in tomato and potato leaves. These compounds include cell wall fragments of both plant and pathogen origin [1-3], abscisic acid [4], jasmonic acid [5] and, most recently, an 18-amino-acid polypeptide, called systemin, isolated from tomato leaves [6]. In this chapter, we describe the properties of systemin and its precursor prosystemin, and we summarize the evidence supporting a role for systemin as an initial signal that regulates proteinase inhibitor synthesis in response to wounding.

Amino Acid Sequence↗
PubMed1992

Effects of mitral regurgitation on pulmonary venous flow and left atrial pressure: an intraoperative transesophageal echocardiographic study.

OBJECTIVES AND BACKGROUND: Pulmonary venous flows recorded by pulsed wave Doppler transesophageal echocardiography examination can be used to assess the severity of mitral regurgitation. Pulmonary venous flows are also related to left atrial pressures; however, the determinants of these flows have yet to be characterized in the presence of mitral regurgitation. METHODS: We simultaneously recorded intraoperative pulmonary venous flows by transesophageal echocardiography and left atrial pressures by direct left atrial puncture in 16 patients with different grades of mitral regurgitation: 2+ (n = 5), 3+ (n = 4) and 4+ (n = 7). Pulmonary venous peak systolic and diastolic flow velocities and peak reversed systolic flow velocities were compared with left atrial pressure a and v waves, a-x and v-y descent values and left atrial volumes. RESULTS: Pulmonary venous systolic to diastolic flow ratios correlated with decreases in left atrial pressure a/v ratios and with increases in the v waves of patients with higher grades of mitral regurgitation. Univariate analysis revealed that the best determinants of the pulmonary venous systolic to diastolic flow ratio were the left atrial pressure v wave (r = -0.76), the v-y descent value (r = -0.73) and the a/v ratio (r = 0.71). Lower correlations were found for left atrial end-systolic (r = -0.48) and end-diastolic (r = -0.42) volumes. Reversed systolic flow was present in patients with 4+ mitral regurgitation, despite left atrial enlargement. CONCLUSIONS: Pulmonary venous flow can be used to assess the severity of mitral regurgitation and reflects the effects of mitral regurgitation severity on the left atrial pressure a and v waves.

Adult↗
PubMed1992

Oligouronide signaling of proteinase inhibitor genes in plants: structure-activity relationships of Di- and trigalacturonic acids and their derivatives.

Polygalacturonic acid (DPave approximately 20), alpha-1,4-di- and trigalacturonic acids, delta 4,5-alpha-1,4-di- and delta 4,5-alpha-trigalacturonic acids, and several chemically modified derivatives of these oligomers were prepared. Their proteinase inhibitor-inducing activities were determined by supplying solutions of the compounds to young, excised tomato plants through their cut stems. Digalacturonic acid, on a molar basis, was the most active oligomer (ED50 approximately 1.5 micrograms/plant), being about three times more active than the parent oligogalacturonic acid (ED50 approximately 5.5 micrograms/plant). The specific inducing activity of trigalacturonic acid was about half that of digalacturonic acid. Both delta 4,5-di- and delta 4,5-trigalacturonic acids were about half as active as di- and trigalacturonic acids, respectively. Reduction of the hemiacetal (carbonyl) group of the di- and trigalacturonic acids with sodium borohydride completely destroyed proteinase inhibitor inducing activities, indicating that the inducing activity of both acids depends upon an intact hemiacetal at the reducing termini. Reduction of the double bonds of delta 4,5-di- and delta 4,5-trigalacturonic acids by catalytic hydrogenation with H2 (palladium catalyst) produced derivatives with specific inducing activities of approximately one-half that of the parent compounds. Thus, while the reducing termini of oligogalacturonides require an intact hemiacetal for proteinase inhibitor inducing activities, the nonreducing termini of the small oligouronides do not require a C4 hydroxyl nor a C5 proton to be active inducers.

Carbohydrate Conformation↗
PubMed1992

Structure, expression, and antisense inhibition of the systemin precursor gene.

A gene that encodes systemin, a mobile 18-amino acid polypeptide inducer of proteinase inhibitor synthesis in tomato and potato leaves, has been isolated from tomato, Lycopersicon esculentum. Induction of proteinase inhibitors in plants is a response to insect or pathogen attacks. The gene has 10 introns and 11 exons, ten of which are organized as five homologous pairs with an unrelated sequence in the eleventh, encoding systemin. Systemin is proteolytically processed from a 200-amino acid precursor protein, prosystemin. Prosystemin messenger RNA was found in all organs of the plant except the roots and was systemically wound-inducible in leaves. Tomato plants transformed with an antisense prosystemin complementary DNA exhibited greatly suppressed systemic wound induction of proteinase Inhibitor I and II synthesis in leaves.

Amino Acid Sequence↗
PubMed1992

Proton NMR assignments of systemin.

Complete proton NMR assignments have been made for a synthetic 18-amino acid peptide named systemin, which functions as a wound-induced polypeptide hormone in tomato plants, and three of its derivatives. The wild-type peptide and this synthetic homolog have equivalent activities in their functional roles as systemic inducing signals in tomato plants. Proton NMR studies were carried out to characterize the solution properties of systemin. A variety of homonuclear proton NMR experiments at both 500 and 600 MHz were utilized in making these assignments, which have resulted in additional structural information. Whereas these results provide no evidence for persistence of common secondary (helix, sheet) or tertiary structural elements in the systemin polypeptide, there is evidence for two distinct molecular conformations at the carboxy terminus.

Amino Acid Sequence↗
PubMed1992

Myocardial protection during cardiac operations. Decreased morbidity and lower cost with blood cardioplegia and coronary sinus perfusion.

The efficacy of myocardial protection with a single aortic crossclamp and blood cardioplegia was evaluated in 819 consecutive patients stratified for preoperative condition by means of a new clinical risk scoring system. A protocol using either antegrade or antegrade/retrograde blood cardioplegia was compared with antegrade crystalloid cardioplegia in 2582 similar, consecutive, and concurrent patients. In the blood cardioplegia cohort, 97 (11.8%) patients had 129 complications compared with 407 (15.8%) patients and 675 complications in the crystalloid cardioplegia group (p = 0.006). In high-risk patients, combined antegrade/retrograde cardioplegia significantly reduced myocardial infarction, stroke, and respiratory and wound complications. Despite the significantly longer aortic crossclamp time required for blood cardioplegia, patients undergoing crystalloid cardioplegia were 1.7 (95% confidence interval 1.3, 2.1) times more likely to have a morbid event. Time in the intensive care unit, length of hospitalization, and length-of-stay outlier status were significantly decreased in the blood cardioplegia compared with the crystalloid cardioplegia group. The net savings in hospital cost amounted to $2196 per case. When compared separately with crystalloid cardioplegia, combined antegrade/retrograde blood cardioplegia accounted for most of the morbidity reduction by significantly reducing perioperative myocardial infarction, wound complications, and length of stay in patients having reoperations. Antegrade/retrograde blood cardioplegia did not influence 1-year survival or event-free survival, even when risk was considered.

Aged↗
PubMed1991

Comparison of OKT3 with ALG for prophylaxis for patients with acute renal failure after cadaveric renal transplantation.

A randomized, prospective comparison of OKT3 vs. ALG (University of Minnesota) was performed in patients who had acute renal failure after a cadaver renal transplantation. Criteria for admission to the study were oliguria or increasing serum creatinine in the first 12 hr after renal transplantation. ALG or OKT3 was administered after randomization beginning 12-36 hours posttransplantation. There were no significant differences in age, sex, original disease, ischemia time, or HLA matching between groups. Graft survivals at 1 and 6 months were 84% and 84%, respectively for the ALG group. One- and 6-month graft survival for the OKT3 group was 88% and 84%, respectively. These differences were not statistically significant. The number of rejection episodes and the number of patients with rejection episodes were greater, and the time to first rejection was shorter in the OKT3 group compared with the ALG group, although none of these differences reached statistical significance. There were significantly less side effects in the ALG group compared with the OKT3 group (P less than .05). The greatest reductions in side effects were in fever and hypotension. Patients were monitored with flow cytometry analysis measuring the number of CD2 (T11) and CD3 (T3) cells to adjust the dose of both OKT3 and ALG. Starting doses were 10 mg/kg/day of ALG and 5 mg/day of OKT3. There were no significant differences in the incidence of infections (viral or bacterial) between the two groups. There were no rejection episodes during the prophylactic therapy with either ALG or OKT3. In summary, both ALG and OKT3 provided effective prophylaxis for patients with acute renal failure after renal transplantation. OKT3 was associated with a statistically significant increase in incidence of symptomatic side effects.

Acute Kidney Injury↗
PubMed1986

Molecular characterization and phylogenetic studies of a wound-inducible proteinase inhibitor I gene in Lycopersicon species.

A gene coding for proteinase inhibitor I, whose expression is induced in tomato leaves (Lycopersicon esculentum L. var. Bonny Best) in response to wounding or insect attacks, was isolated from a genomic library and characterized. The nucleotide sequence revealed that the gene is complete and encodes the sequence of an inhibitor I cDNA that was previously isolated from a cDNA library prepared from wound-induced mRNA from tomato leaves. This gene is located 13.1 kilobase pairs (kbp) upstream from an inhibitor II gene. The wound-inducible gene is interrupted by two intervening sequences of 445 and 404 bp, situated within the codons of amino acids 17 and 47, respectively, of the open reading frame. In addition to the presence of putative regulatory sequences, TATAAA and CCACT, two copies of an imperfect direct repeat approximately 100 bp long were identified in the 5'-flanking region. Phylogenetic comparisons of wound-inducible inhibitor I genes within the genomes of various Lycopersicon species revealed that the repeat is found in seven ancestral species of tomato.

Amino Acid Sequence↗
PubMed1985

Wound-induced proteinase inhibitors from tomato leaves. I. The cDNA-deduced primary structure of pre-inhibitor I and its post-translational processing.

A cDNA containing the coding region for the complete amino acid sequence of wound-induced proteinase Inhibitor I from tomato leaves was constructed in the plasmid pUC9 and characterized. The open reading frame codes for a protein of 111 amino acids. This deduced amino acid sequence revealed the presence of a 42-amino acid N-terminal sequence that is not found in the native protein. This sequence appears to contain a 23-amino acid segment typical of a signal sequence followed by a 19-amino acid sequence containing 9 charged amino acids. The 42-amino acid sequence is apparently lost during maturation to the native Inhibitor I and represents 38% of the translated protein. The Inhibitor I amino acid sequence contains 71% identity with potato tuber Inhibitor I sequence and 35% identity with an inhibitor from the leech.

Amino Acid Sequence↗
PubMed1985

Wound-induced proteinase inhibitors from tomato leaves. II. The cDNA-deduced primary structure of pre-inhibitor II.

A cDNA containing the complete amino acid-coding region of wound-induced tomato Inhibitor II was constructed in the plasmid pUC9. The open reading frame codes for 148 amino acids including a 25-amino acid signal sequence preceding the N-terminal lysine of the mature Inhibitor II. The Inhibitor II sequence exhibits two domains, one domain having a trypsin inhibitory site and the other a chymotrypsin inhibitory site, apparently evolved from a smaller gene by a process of gene duplication and elongation. The amino acid sequence of tomato leaf Inhibitor II exhibits homology with two small proteinase inhibitors isolated from potato tuber and an inhibitor from eggplant. The small potato tuber inhibitors are homologous with 33 amino acids of the N-terminal domain and 19 amino acids from the C-terminal domain. Two identical nucleotide sequences of Inhibitor II cDNA in the 3' noncoding region were present that were also found in an Inhibitor I cDNA. These include an atypical polyadenylation signal, AATAAG, and a 10-base palindromic sequence, CATTATAATG, for which no function is yet known.

Amino Acid Sequence↗
PubMed1984

Isolation and characterization of the proteinase inhibitor-inducing factor from tomato leaves. Identity and activity of poly- and oligogalacturonide fragments.

Mild acid hydrolysis of a small (Mr = 6 kDa) pectic polysaccharide isolated from tomato leaves, an inducer of the synthesis and accumulation of two proteinase inhibitors in excised tomato plants, yielded a alpha-D-polygalacturonic acid polymer with degree of polymerization = 20 that retained proteinase inhibitor-inducing activity. Enzymic and acid hydrolysis of this polygalacturonan yielded a series of alpha-1,4-D-galacturonic acid oligomers with degrees of polymerization from 2 to 6 which were purified to homogeneity and assayed for proteinase inhibitor-inducing activity in young excised tomato plants. All of the oligomers exhibited activity. The hexagalacturonide possessed the highest activity and the trimer the lowest. The evidence supports a possible role for plant cell wall fragments as systemic messengers that regulate the expression of proteinase inhibitor genes in plant leaves in response to pest attacks.

Carbohydrates↗
PubMed1984

Isolation and characterization of proteinase inhibitor I from etiolated tobacco leaves.

Proteinase Inhibitor I was induced to accumulate in tobacco (Nicotiana tabaccum) leaves by placing plants in darkness for 10 days at 27 degrees C. The inhibitor was isolated using ammonium sulfate precipitation, Sephadex G-75 chromatography, heating, and affinity chromatography with a chymotrypsin-Sepharose column. Inhibitor I was purified 232-fold with a yield of 34 mg from 2.5 kg of leaves. Affinity-purified tobacco Inhibitor I was shown to be homogeneous by gel electrophoresis in both nondissociating and dissociating buffers. The inhibitor has a molecular weight of 39,000 +/- 1000 determined by gel filtration and, like its potato and tomato counterparts, is composed of five subunits of molecular weight 8100. The tobacco Inhibitor I strongly inhibits chymotrypsin and weakly inhibits trypsin. The chemical, physical, and immunological properties of tobacco Inhibitor I indicate that it is structurally very similar to potato tuber Inhibitor I and tomato leaf Inhibitor I, although the synthesis and accumulation of the three inhibitors in their respective tissues are all under different developmental or environmental regulation.

Chemical Phenomena↗
PubMed1984

Nutritional studies of a carboxypeptidase inhibitor from potato tubers.

Carboxypeptidase inhibitor from potato tubers was fed to newly hatched chicks at a level equal to that present in diet containing 50% raw potato, which caused severe growth depression and 20% mortality. At this level the effects of the inhibitor on growth was small but the following effects were noted: (a) increased fecal protein (the increase mainly consisting of low molecular weight proteins); (b) poorer feed efficiency; and (c) a significant decrease in pancreatic digestive proenzyme levels, although no hypertrophy was noted. In addition, the inhibitor was not digested readily in the intestinal tract and it increased in concentration in intestinal contents as it progressed down the tract. Potato Inhibitor II, a potent trypsin inhibitor, when fed to chicks, also at the level found in a 50% raw potato diet, was severely growth depressing. It significantly increased fecal protein and caused pancreatic hypertrophy. The trypsin inhibitor may be a major growth depressing agent in raw potatoes whereas the carboxypeptidase inhibitor probably contributes little to the growth depression.

Animals↗
PubMed1983

A rapid, large-scale method for purification of the metallo-carboxypeptidase inhibitor from potato tubers.

A rapid, large-scale procedure has been developed for the preparation of metallo-carboxypeptidase inhibitor (CPI) from potatoes. The inhibitor is extracted with 80% ethanol from partially cooked potato tubers. After the ethanol is removed and the salts are dialyzed away, the inhibitor is isolated in pure form by chromatography on sulfopropyl Sephadex. Ten pounds of potatoes yields 250 mg pure inhibitor, representing over 40% recovery. Commercial mashed potato flakes contain about 0.02% carboxypeptidase inhibitor and can be utilized as a starting material in the procedure described to yield over 70 mg inhibitor from a pound of flakes.

Hot Temperature↗