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Biomedical subjects

C A Ryan

Publications and source records attributed to C A Ryan.

At least 199 records · Page 11Linked to original sources
PubMed1987

The use of povidone iodine in neonatal bowel surgery.

The ostomy sites of four premature infants undergoing bowel reanastomosis were lavaged with a 10% solution of povidone iodine to reduce local bacterial contamination and the risk of anastomosis dehiscence. There was a significant decrease in serum thyroxin from 112 (+/- 11) mumol/L to 90 (+/- 33) mumol/L 24 hours following surgery (P less than .05), but no change in serum thyroid stimulating hormone (TSH). The total serum iodine rose from 1.5 (+/- 0.05) mumol/L before surgery to 61.6 (+/- 46.4) mumol/L 24 hours later and urinary iodine excretion was 60 times the preoperative value in the second 24 hours following surgery. Both the hormonal and biochemical indices returned to normal 2 weeks following surgery except for total serum iodine, which remained slightly elevated. Povidone iodine is a safe and effective antiseptic agent. However, as it may cause transient suppression of thyroid function in neonates, thyroid status should be tested in all such infants at approximately 2 weeks following repeated or widespread use.

Humans↗
PubMed1987

Wound-inducible expression of a potato inhibitor II-chloramphenicol acetyltransferase gene fusion in transgenic tobacco plants.

A potato inhibitor II gene (IIK) was isolated from a library of potato genes in lambda bacteriophage. An 8-kilobase-pair (kbp) insert was identified using a tomato inhibitor II cDNA as a hybridization probe, and a 2.6-kbp fragment containing the gene was subcloned into the plasmid pUC13 and characterized. The nucleotide sequence of the isolated gene exhibited 87% identity with the wound-inducible tomato inhibitor II cDNA sequence. The amino acid sequence of inhibitor IIK, deduced from the potato gene, exhibited 84% identity with the tomato inhibitor II protein. A 1000-bp restriction fragment from the 5' flanking region of the gene was fused to the open reading frame of the chloramphenicol acetyltransferase (CAT) gene. This fusion was terminated in two ways: (i) with a terminator sequence from the potato inhibitor II gene and (ii) with a terminator from the 6b gene of Ti plasmid pTiA6. These chimeric genes were transferred into tobacco cells via a binary Ti vector system, and transgenic plants were regenerated. The CAT gene was expressed in leaves of transformed plants in response to wounding when fused with the inhibitor IIK promoter and terminator regions. The chimeric gene containing the 6b terminator did not express CAT in response to wounding. The wound-inducible expression of CAT activity was systemic and was induced in tissues distal to the wounded tissues. The time course of wound induction of CAT activity in transgenic tobacco leaves is similar to that found for wound-inducible inhibitor I and II mRNAs in tomato leaves. These results demonstrate that sequences necessary and sufficient for wound inducibility are present within approximately 1000 bp of the control regions of the inhibitor IIK genes and that wound-inducible components of tobacco leaf cells can regulate these sequences.

Journal Article↗
PubMed1987

Inhibition of radiation-induced transformation of C3H/10T1/2 cells by chymotrypsin inhibitor 1 from potatoes.

In this report, we have investigated whether a protease inhibitor obtained from potatoes (chymotrypsin inhibitor 1; CI-1) will inhibit carcinogen-induced transformation of C3H/10T1/2 cells. CI-1 was as effective as the soybean-derived Bowman Birk inhibitor at suppressing radiation-induced transformation of C3H/10T1/2 cells, at a concentration of 10 micrograms/ml. The inhibitor was not toxic to the cells at concentrations of 0.1-10 micrograms/ml, the concentrations of CI-1 employed in the transformation experiments. To investigate the interaction of this inhibitor with the target cells, binding studies were carried out. 125I-labelled CI-1 could not be displaced from C3H/10T1/2 cells by co-incubation of the cells with a 5000-fold excess of unlabelled inhibitor. These results suggest that this inhibitor does not reversibly bind to specific receptor proteins on the surface of these cells.

Animals↗
PubMed1987

Chymotrypsin-specific protease inhibitors decrease H2O2 formation by activated human polymorphonuclear leukocytes.

Stimulated phagocytic cells generate active oxygen species which are known to contribute to inflammatory diseases, necrosis of surrounding tissues, mutagenicity and carcinogenicity. Until now, it was not certain whether protease inhibitors are capable of decreasing the production of those oxygen species, and if they are, what type of protease inhibitor is the most active. In this work we monitored formation of H2O2 by 12-O-tetradecanoylphorbol-13-acetate (TPA)-activated polymorphonuclear leukocytes (PMNs) because H2O2 is the immediate precursor of the actual damaging species. These determinations were carried out in the absence or presence of protease inhibitors and/or superoxide dismutase (SOD). The protease inhibitors tested were: potato inhibitors 1 (PtI-1) and 2 (PtI-2), a chymotrypsin-inhibitory fragment of PtI-2 (PCI-2), chicken ovoinhibitor (COI), turkey ovomucoid ovoinhibitor (TOOI), Bowman-Birk inhibitor (BBI), lima bean inhibitor (LBI) and soybean (Kunitz) trypsin inhibitor (SBTI). The order of activity, as measured by inhibition of H2O2 formation by TPA-activated PMNs during incubation at 37 degrees C for 30 min, was (in descending order): PtI-1 greater than or equal to PCI-2 greater than PtI-2 greater than COI greater than BBI greater than or equal to TOOI greater than LBI greater than SBTI. Thus, the most effective were the chymotrypsin-specific inhibitors PtI-1 and PCI-2, followed by the bifunctional inhibitors recognizing both chymotrypsin and trypsin, and the least active was SBTI, a predominantly trypsin inhibitor. At the higher concentrations of protease inhibitors tested, the inhibitory activity was similar in both the absence and presence of SOD. These results show that protease inhibitors specific for chymotrypsin but not those that are trypsin-specific are capable of inhibiting formation of active oxygen species during the oxidative burst of stimulated human PMNs.

Chymotrypsin↗
PubMed1987

Comparison of high-frequency chest wall compression with conventional mechanical ventilation in cats.

Six anesthetized paralyzed cats with normal lungs were ventilated by high-frequency chest wall compression (HFCWC) at 5 Hz using a single-chamber circumferential cuff enclosing the thorax from the axillae to the xiphisternum. PaCO2 during HFCWC + PEEP (3 cm H2O) was significantly (p less than .0005) lower compared with conventional mechanical ventilation (CMV). End-expiratory lung volume (VL) during HFCWC + PEEP was significantly (p less than .001) lower than VL during CMV + PEEP but was higher than VL during CMV without PEEP. After the cats' lungs were stiffened by repeated saline lavage, CMV + PEEP at a mean airway pressure (Paw) of 10 cm H2O was compared with HFCWC + continuous positive airway pressure (CPAP) at an equal or lower Paw. A significant decrease in PaCO2 (p less than .02) during HFCWC occurred but no significant differences were observed in PaO2, VL, or compliance. Arterial BP and cardiac output were similar between CMV + PEEP and HFCWC + CPAP. In cats with normal lungs, VL can be maintained by applying CPAP during HFCWC, and in those with injured lungs, HFCWC + CPAP produces comparable gas exchange at a Paw equal to or lower than that used during CMV + PEEP.

Animals↗
PubMed1987

The effects of negative pressure external high frequency oscillation on cerebral blood flow and cardiac output of the monkey.

The cerebral and systemic hemodynamic effects of negative pressure ventilation by external high frequency oscillation, utilizing a thoracoabdominal chamber, were investigated in six healthy adult monkeys. Cardiac output and cerebral blood flow were compared on external high frequency oscillation and conventional, positive pressure, mechanical ventilation in each animal. Cardiac output was measured by thermodilution and cerebral blood flow was measured by the intraarterial Xenon133 clearance technique. Oxygen delivery and consumption and systemic and pulmonary vascular resistances were calculated. There was no significant difference between the two ventilatory modes for any of these variables. Cardiac index on conventional mechanical ventilation was 2.87 +/- 0.39 1 X min-1 X m-2 (mean +/- SD) and on external high frequency oscillation was 2.96 +/- 0.87 1 X min-1 X min-2. Cerebral blood flow was 43.9 +/- 9.1 ml X 100 g-1 X min-1 on conventional and 39.0 +/- 9.0 ml X 100 g-1 X min-1 on external high frequency ventilation. External high frequency oscillation is not associated with any adverse cardiovascular or cerebrovascular effects and could be introduced for short-term human trials.

Animals↗
PubMed1987

Contralateral pneumothoraces in the newborn: incidence and predisposing factors.

A prospective study was performed to ascertain the incidence of, and risk factors for, the development of a contralateral pneumothorax in 32 neonates with respiratory distress, without evidence of pulmonary hypoplasia, who had an initial unilateral air leak requiring pleural drainage. The mean postnatal age of occurrence of the first pneumothorax was 31.04 hours (range 0.1 to 92 hours); a subsequent contralateral pneumothorax developed in 14 infants (44%) at a mean postnatal age of 61.5 hours (range 8 to 106 hours). Thirteen of the 14 infants with a subsequent contralateral pneumothorax had pulmonary interstitial emphysema visible on the chest radiograph taken immediately after drainage of the first pneumothorax, compared with eight of the 18 infants without a contralateral pneumothorax (P less than .005). Other factors significantly associated with a contralateral pneumothorax were alveolar-arterial oxygen gradient (P less than .01) and FiO2 (P less than .005), both measured one hour after the pneumothorax, and gestational age (P less than .05). Multivariate discriminant function analysis did not usefully add to the predictive power of pulmonary interstitial emphysema alone. Infants with pulmonary interstitial emphysema at the time of an initial unilateral pneumothorax are at significant risk for the development of a contralateral pneumothorax.

Bronchopulmonary Dysplasia↗
PubMed1986

Regulation of proteinase inhibitor genes in food plants.

Proteinase inhibitor proteins in the families Solanaceae, Leguminosae and Graminae are stored in seeds and tubers and are also found to accumulate in leaves in response to pest attacks. The isolation of the proteinase Inhibitor I cDNA and its gene from tomato has provided information concerning proteinase inhibitor synthesis, processing and compartmentation in leaves under pest attacks. Strategies are now being developed using proteinase inhibitor genes, to genetically engineer the quantity and quality of these potentially defensive and highly nutritional proteins of important crop plants.

Amino Acid Sequence↗
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↗
PubMed1986

Escherichia coli O157:H7 diarrhea in a nursing home: clinical, epidemiological, and pathological findings.

In September 1984, an outbreak of Escherichia coli O157:H7 infection occurred in a nursing home. It was the first recognized outbreak of this organism in the United States since 1982, when two outbreaks led to its recognition as a pathogen. Thirty-four of 101 residents developed a diarrheal illness; 14 were hospitalized with a severe illness characterized by crampy abdominal pain, marked abdominal distention, and grossly bloody diarrhea, and four died. The spectrum of illness associated with the infection was broad and included the following: asymptomatic infection, nonbloody diarrhea, hemorrhagic colitis, hemolytic uremic syndrome, and death. Clinical, radiographic, and postmortem pathological findings suggested involvement of the cecum and right colon. No evidence of response to antimicrobial agents could be documented, and antidiarrheal agents may have aggravated the disease. This investigation implicated hamburger as the vehicle transmission. Seventeen of 19 residents with hemorrhagic colitis, but only 28 of 67 healthy residents, had eaten hamburger on 13 September (P less than .001, Fisher's two-tailed exact test; relative risk [RR] = 7.7). Infection with E. coli O157:H7 can cause a wide range of manifestations. In the elderly these can be particularly severe and may resemble ischemic colitis.

Adult↗
PubMed1986

Proteinase inhibitor I accumulation in tomato suspension cultures : induction by plant and fungal cell wall fragments and an extracellular polysaccharide secreted into the medium.

Suspension-cultured cells of tomato accumulate proteinase Inhibitor I as the sucrose is depleted from 1% to less than 0.1% in the culture medium. Inhibitor I can be prematurely induced to accumulate in the cells by the addition to the medium of the proteinase inhibitor inducing factor, trigalacturonic acid, ethylene glycol chitin, or chitosan. In cultures grown in 0.6% initial sucrose with no inducers added, a uronic acid-rich extracellular polysaccharide appears in the medium during growth of the cells. This extracellular polysaccharide apparently contains an ;endogenous inducer' of Inhibitor I synthesis. When the partially purified polysaccharide is added to the culture medium, Inhibitor I accumulation is induced. Proteinase inhibitors also accumulate in tobacco and alfalfa suspension-cultured cells as the cell cultures age. As with the tomato cultures, a uronic acid-rich component(s) appears in the media prior to inhibitor accumulation. These data suggest that an endogenous inducer may be activating proteinase inhibitor genes through a similar mechanism in all three types of cells.

Journal Article↗
PubMed1986

External high frequency oscillation in cats. Experience in the normal lung and after saline lung lavage.

In an effort to develop a method of assisted ventilation that would avoid endotracheal intubation, 11 anesthetized, paralyzed, nonintubated adult mongrel cats with normal lungs were externally oscillated by means of a thoracoabdominal chamber connected to a vacuum source and a high frequency oscillator. Chamber pressure was adjusted to the desired negative pressure using the vacuum source, and the animal was then oscillated above and below this pressure. The lowest PaCO2 and AaPO2 were observed at 3 Hz. Tidal volume (VT) fell (p less than 0.001) with increases in frequency, and lung volume (VL) rose with increased negative chamber pressure (p less than 0.001). In 11 additional tracheostomized cats, a stiff lung was created by repeated saline lung lavage. External high frequency oscillation (EHFO), using pressures comparable to those used for conventional mechanical ventilation (CMV), was associated with a significant increase in PaO2 (p less than 0.001), and a significant fall in AaPO2 (p less than 0.01) compared with that during CMV. Lung volume was significantly higher during EHFO (p less than 0.001) and, as in the normal lung, VT fell with increasing frequencies to 15 Hz (p less than 0.001). There were no significant frequency-dependent variations in gas exchange or VL. An increasingly negative mean chamber pressure was associated with a significant increase in PaO2 (p less than 0.05) and VL(p less than 0.005) and a significant decrease in PaCO2 (p less than 0.025).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Prostacyclin production by isolated rat adipocytes: evidence for cyclic adenosine 3',5'-monophosphate-dependent and independent mechanisms and for a selective effect of insulin.

The rat adipocyte contains two separate mechanisms for prostaglandin (PG) production. Norepinephrine stimulates prostacyclin (PGI2) and PGE2 production and triglyceride lipolysis in isolated rat adipocytes. In contrast, the vasoactive peptides angiotensin II, vasopressin, and bradykinin stimulate PGI2 production, but not PGE2 production or triglyceride lipolysis, in these cells. In this study, we characterized the two separate mechanisms of PG production with respect to the time course, the role of cAMP, the identity of the adrenergic receptor, and the effects of insulin and glucocorticoids. Angiotensin II stimulated PGI2 production rapidly (at 5 min) and independently of cAMP. beta-Adrenergic stimulation with isoproterenol produced a rapid 11-fold increase in the cAMP concentration and stimulated PGI2 production more slowly (at 120 min). The phosphodiesterase inhibitor 1-methyl-3-isobutylxanthine (0.2 and 0.5 mM) and the adenylate cyclase activator forskolin (10 microM) also stimulated cAMP production rapidly and PGI2 production more slowly. 1-Methyl-3-isobutylxanthine (5.0 mM) further stimulated cAMP levels, but prevented the increase in PGI2 production and blunted the increase in glycerol release seen at lower concentrations. beta-Adrenergic blockade with propranolol or timolol completely inhibited the norepinephrine- or isoproterenol-stimulated production of PGI2 and triglyceride lipolysis, respectively. Insulin selectively inhibited isoproterenol-stimulated PGI2 production and triglyceride lipolysis at physiological concentrations, but had no effect on angiotensin II-stimulated PGI2 production. In contrast, dexamethasone inhibited PGI2 production induced by both isoproterenol and angiotensin II. We conclude that: angiotensin II stimulates PGI2 production rapidly and independently of cAMP, but isoproterenol stimulates PGI2 production more slowly, an effect that is cAMP dependent; insulin inhibits the cAMP-dependent beta-adrenergic stimulation of PGI2 production (and triglyceride lipolysis), but not the cAMP-independent angiotensin II-induced stimulation of PGI2 production (this suggests that the former effect is mediated by a decrease in cAMP levels in the adipocyte); and dexamethasone inhibits both mechanisms of PGI2 production. Both mechanisms of PGI2 production by rat adipocytes are exquisitely sensitive to hormonal regulation.

1-Methyl-3-isobutylxanthine↗
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↗