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Biomedical subjects

C Ma

Publications and source records attributed to C Ma.

214 records · Page 12Linked to original sources
PubMed1985

The chloroplast genome of Carthamus tinctorius.

A physical map of safflower (Carthamus tinctorius L.) chloroplast DNA has been generated using SalI, PstI, KpnI and HindIII restriction endonucleases. Southern blots to single and double digests by these enzymes were hybridized with 32P-dCTP nick-translated KpnI probes, which were individually isolated from agarose gels. The plastid genome was found to be circular (151 kbp), to contain a repeated sequence of about 25 kbp, and to have small and large single copy regions of approximately 20 and 81 kbp, respectively. Heterologous probes from spinach and Euglena containing psbA, rbcL, atpA or rrnA structural genes were also hybridized with such single and double restriction enzyme digests and mapped on this circular chloroplast genome. The genetic map was found to be co-linear with that of spinach and many other higher plants.

Autoradiography↗
PubMed1985

Isolation and characterization of safflower (Carthamus tinctorius L.) chloroplast DNA.

Safflower (Carthamus tinctorius L.) chloroplasts were isolated and purified with the aid of commercially available nylon mesh, differential centrifugation, and DNase I treatment. These chloroplasts were free of nuclei as determined by light microscopy of aceto orcein stained preparations, and similar to those observed by electron microscopy in spinach and many other higher plants, being bounded by a double membrane layer and characterized by the presence of a lamellar system surrounded by embedding matrix, and stacked membranes or grana lamallae. DNA was isolated and purified from such chloroplasts, and characterized with respect to cesium chloride density gradient isopycnic centrifugation, denaturation, renaturation kinetics and restriction enzyme analysis. These studies show that safflower chloroplast DNA is similar to many other higher plant DNAs having a density of 1.700 g/cm3 (G + C = 40.8%), a Tm of 86 degrees C (G + C = 40.7%) and a molecular complexity and genome size of about 10(8) daltons.

Chloroplasts↗
PubMed1985

Myocardial hemodynamics during induced hypotension: a comparison between sodium nitroprusside and adenosine triphosphate.

Adenosine triphosphate (ATP) has been reported to be a hypotensive agent similar in effect to sodium nitroprusside (SNP). The purpose of this study was to examine and compare the effects of both SNP and ATP on general coronary hemodynamics, myocardial O2 consumption, and circulating catecholamines. Twelve dogs were anesthetized with 1.0% halothane and given either SNP or ATP by controlled infusion to reduce their systemic blood pressure by 50% for a 2-h period followed by a (blood pressure) recovery period. The ATP-induced hypotension was rapid, easily controlled, not accompanied by tachyphylaxis over the 120 min studied, and resulted in an increase in coronary sinus blood flow (CSBF), which plateaued at 260% above control. The increase in CSBF was almost immediate and remained at this elevated level for the duration of the induced hypotension. During the ATP-induced hypotension, there was no change in heart rate or circulating catecholamines. A 60% reduction in myocardial O2 uptake was observed, presumably from the cardiac unloading. In contrast, SNP-induced hypotension required a marked increase in dose over time, did not significantly increase CSBF, did increase heart rate, and resulted in large increases in circulating plasma catecholamines. Neither agent affected cardiac output. ATP-induced hypotension resulted in no change in cardiac lactic acid uptake, while SNP caused lactic acid production, indicating possible cardiac ischemia or cyanide toxicity.

Adenosine Triphosphate↗
PubMed1985

Effects of verapamil on uterine blood flow and maternal cardiovascular function in the awake pregnant ewe.

Calcium entry blocking drugs may have a role in the treatment of maternal and fetal tachyarrhythmias, as well as for treatment of premature labor. This study was undertaken to assess the hemodynamic effects of verapamil in the awake pregnant ewe. Verapamil, 0.2 mg/kg administered intravenously over 3 min, resulted in the following maternal cardiovascular changes: transient (2 min) but significant decreases in systolic, diastolic, and mean blood pressures, and significant but equally transient increases in central venous pressure and mean pulmonary arterial pressure. Pulmonary capillary wedge pressure increased for 5 min. These results are consistent with the negative inotropic and peripheral vasodilating effects of verapamil. Cardiac output, systemic vascular resistance, and pulmonary vascular resistance were unaffected. Uterine blood flow decreased 25% at 2 min and remained significantly (7-18%) below control levels for 30 min after drug injection. The effects of verapamil on uterine blood flow suggest that it should be used with caution in cases where uteroplacental perfusion is compromised.

Animals↗
PubMed1984

Adverse behavioral effects of the anticholinesterase poisoning protector pralidoxime methanesulfonate.

Pralidoxime methanesulfonate (P2S) has anticholinesterase protective properties, but it also has an array of gastrointestinal (GI) symptoms. Because such a symptom would be disadvantageous to occupational workers who handled and used organophosphorus anticholinesterase continuously, and to soldiers who have had oral pretreatment in a situation where anticholinesterase agent poisoning is a possibility, this question was investigated in rats using three behavioral paradigms to evaluate the feasibility of the oral prophylactic regimen. These are: (1) conditioned taste aversion (CTA), (2) operant behavior and (3) spontaneous locomotor activity (SMA); these three behavioral parameters are analogous to toxicant-induced gastrointestinal (GI) disturbances, performance of learned tasks and behavioral arousal, respectively. Dose-response studies of P2S in dose levels of 0.2, 0.4, 0.8 and 1.6 gm/kg (P.O.) were evaluated. The results consistently demonstrated that only the highest dose significantly produced marked decreases in consumption of flavored solution associated with its ingestion, suppressed keypress response maintained under a 20-response fixed-ratio schedule of water presentation, and inhibited SMA. By inference, if CTA, operant behavior and SMA are appropriate paradigms, P2S, on an acute single oral high dose level, would cause GI disturbances, impair task performance and induce sedation in man.

Animals↗
PubMed1983

Clinical and histological observations on the application of intermingled auto- and porcine-skin heterografts in third degree burns.

Escharectomy and skin grafting with both homograft and porcine skin has become an effective method in treating massive third degree burns. Seventeen patients and 21 operations of intermingled transplantation of auto- and fresh porcine skin heterografts after escharectomy of the severe burn wounds have been carried out since March 1973. Clinical and histological data are summarized, among which we observed the 'fusing phenomena' of auto- and porcine skin heterografts in 6 patients. Vascularization, 'turning red', viability and rejection as well as ways to improve the results of the grafting method are discussed. No vascular communication between fresh porcine skin and the host wound has been observed during the early postoperative period. The cause of 'turning red' is a reddish transudation between the graft and the host wound seen through the thin porcine skin. Based on histological observations, porcine skin is viable after transplantation. With nutritional support apparently coming from the underlying plasma and tissue fluid. Eventually the process of rejection is similar to that of homograft Better results are found with porcine skin grafts 0.4-0.5 mm in thickness placed 0.5-0.75 cm apart. In order to avoid large sloughing wound surfaces less than 20 per cent area of porcine skin coverage is advisable.

Adolescent↗
PubMedDate not supplied

Relationship between radioprotective and neuromotor effects of S-2(3-aminopropyl-amino)ethylphosphorothioate (WR-2721) in mice.

The radioprotective and neuromotor effects of WR-2721 were studied in male albino ICR strain mice. The protective activity was evaluated by graded doses of WR-2721 (50-400 mg/kg, IP) against whole body 60Co gamma irradiation at a single maximal lethal threshold dose rad (i.e., 1250 rad). The neuromotor effects of the drug were assayed by its action, at the same dose range as used in the protection assay, on spontaneous motor activity (SMA) and wire hanging performance (WHP). Drug doses were administered 30 min before radiation exposure and neurobehavioral testings. The results showed a dose-dependent increase in radioprotection and an inhibition in the neuromotor tasks. The radioprotective efficacy was seen at doses at which intrinsic neuromotor deficits were detected (100-400 mg/kg). A dose-related parallelism of protective efficacy and neurobehavioral toxicity (i.e., SMA inhibition and WHP disruption) was also observed. The present findings suggest that WR-2721 induces neuromotor dysfunctions along with its radioprotectivity.

Amifostine↗
PubMedDate not supplied

Effect of the radioprotector WR-2721 on operant behavior in the rat.

The effect of WR-2721 on performance maintained by a fixed-ratio 20 (FR-20) schedule for water reinforcement was studied in male Sprague-Dawley rats. Graded doses of WR-2721 (range 25-100 mg/kg) were administered IP immediately prior to a 60 min test session. WR-2721 had a dose dependent monotonic disruptive effect on FR responding, with significant effects at doses of 50, 75 and 100 mg/kg. WR-2721 also decreased postsession water consumption, but only one significant effect at the highest dose (100 mg/kg). Both slopes of the dose-response regression line are parallel in effect. These data indicate that WR-2721 may affect drinking motivation, which could disrupt operant performance, and WR-2721 affects motor behavior at lower doses than those that depress "motivation" to drink. The log dose-probit analysis on the all-or-none disruptive pattern of pause of responding observed from cumulative records disclosed that the slope of this regression line (s = 1.11) was also almost identical to that of reinforcer decrement analyzed from graded dose-response relationship (s = 1.14) and shared the same estimated ED50's (58.5 and 55.6 mg/kg, respectively). A preliminary study using a variety of pharmacological interventions was also carried out to ascertain if the general functional gastrointestinal disorders produced by WR-2721 may subserve the behavioral deficits. Subcutaneous pretreatments with various selective, peripherally active, gastroprotective drugs [cimetidine (30 and 60 mg/kg), pirenzepine (5 and 10 mg/kg) and domperidone (1, 5 and 10 mg/kg)] 30 min prior to challenge with WR-2721 at dose of 100 mg/kg, demonstrated that these drugs did not yield any apparent significant attenuative effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Amifostine↗
PubMedDate not supplied

Quantitative structure-activity relationships and possible mechanisms of action of bispyridinium oximes as antidotes against pinacolyl methylphosphonofluoridate.

The antidotal efficacy of bispyridinium oximes against the poisoning by pinacolyl methylphosphonofluoridate can be correlated well with their physicochemical parameters. Good correlation was observed between the efficacy of antagonism against pinacolyl methylphosphonofluoridate and antinicotinic action of these oximes. X-ray structural analysis showed that these oximes possessed structural similarity to nicotine and acetylcholine of nicotinic conformation. A new model of antidotal action, other than reactivation, against the poisoning by pinacolyl methylphosphonofluoridate was proposed for these bispyridinium oximes through nicotinic receptor binding. The antagonistic efficacy of these antidotes against pinacolyl methylphosphonofluoridate may be attributed to their direct antagonism at nicotinic receptor as well as reactivation of inhibited acetylcholinesterase.

Animals↗
PubMedDate not supplied

Differential expression of transforming growth factor-beta 1 and transforming growth factor-beta receptors in myometrium of women with failed induction of labor, no labor, and preterm labor.

OBJECTIVE: Comparative analysis of transforming growth factor-beta 1 (TGF-beta 1) and TGF-beta receptor type I and type II messenger RNA (mRNA) and protein expression in myometrium of women who had unsuccessful labor induction, with those without labor or in preterm labor complicated by chorioamnionitis. METHODS: Small segments of myometrium were collected from women who were undergoing cesarean delivery for unsuccessful labor induction (n = 5), elective cesarean without labor (n = 5), or cesarean delivery for complications related to preterm labor and chorioamnionitis (n = 5). Total RNA was isolated from these tissues and subjected to competitive quantitative reverse-transcription-polymerase chain reaction (Q-RT-PCR) to determine the level of TGF-beta 1, and TGF-beta type I and type II receptor mRNA expression. Tissue sections were prepared from paraffin-embedded specimens and immunostained for TGF-beta 1 and receptor proteins using specific polycolonal antibodies. The data were analyzed by impaired Student t test and Kruskal-Wallis analysis of variance. RESULTS: Myometrium from women who had unsuccessful labor induction expressed higher levels of TGF-beta 1 mRNA (2.21 +/- 0.28 x 10(6) copies/microgram of total cellular RNA) than those with preterm labor (4.53 +/- 0.2 x 10(5) copies), or without labor [3.13 +/- 2.6 x 10(4) copies (P < .05)]. The level of TGF-beta type I receptor mRNA expression did not vary; however, type II receptor expression was significantly lower in myometrium from preterm labor (1.36 +/- 0.36 x 10(5) copies) compared with those from unsuccessful labor induction (3.42 +/- 0.42 x 10(6) copies) or without labor (9.65 +/- 3.2 x 10(5) copies). Immunoreactive TGF-beta 1 and TGF-beta receptor proteins were present in all myometrial tissues, and their intensity reflected that of the mRNA expression in these tissues. CONCLUSION: TGF-beta 1 and TGF-beta type II receptors are expressed differently in myometrium of women who had unsuccessful labor induction compared with those without labor or with preterm labor complicated by chorioamnionitis. Because TGF-beta is a key regulator of tissue remodeling which is central to initiation of normal labor, alterations in TGF-beta and/or TGF-beta receptor expression may lead to changes in the outcome of labor, at least at the myometrial level.

Cesarean Section↗
PubMedDate not supplied

Role of transforming growth factor beta-1 in peritonitis-induced adhesions.

Peritonitis is a major cause of intra-abdominal adhesion formation. The overexpression of transforming growth factor beta-1 (TGF-Beta1), a potent mitogen, chemoattractant, and stimulant for collagen synthesis by fibroblasts, has been linked to tissue fibrosis at various sites throughout the body including peritoneal adhesion formation. Hence we hypothesized that the mechanism(s) involved in peritonitis-induced adhesion formation may be mediated through the upregulation of TGF-Beta1 expression. Peritonitis was induced in rats by cecal ligation and puncture, while a control group underwent sham operation. Adhesions were scored and harvested from both groups at 0, 6 and 12 hours and at 1, 2, 4, 7, and 28 days. Tissue expression of TGF-Beta1 mRNA was determined by quantitative reverse transcription-polymerase chain reaction and TGF-Beta1 protein was localized by immunohistochemical analysis. Serum and peritoneal fluid TGF-Beta1 concentrations were quantified by enzyme-linked immunosorbent assay. Compared with sham operation, peritonitis was associated with a significantly greater incidence of abdominal adhesions and a significant increase in the levels of TGF-Beta1 mRNA expression at days 2, 4, and 7. Immunostaining intensity of TGF-Beta1 in adhesions from the peritonitis group also steadily rose through day 7. In peritoneal fluid, the ratio of active:total TGF-Beta1 was significantly increased in the peritonitis group on days 1, 2, and 4 compared with the sham group. These results suggest that peritonitis is associated with the upregulation of TGF-Beta1, a mechanism that may exacerbate adhesion formation.

Animals↗
PubMedDate not supplied

Expression of matrix metalloproteinases and tissue inhibitor of matrix metalloproteinases in mesothelial cells and their regulation by transforming growth factor-beta1.

Tissue injury and pelvic inflammation often results in peritoneal scar tissue formation. The objective of this study was to determine whether mesothelial cells which line the peritoneal cavity express matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs), and if their expression is regulated by transforming growth factor-beta1, a key regulator of tissue fibrosis. For this purpose we used Met-5A cells, a cell line derived from human normal mesothelial cells, and for comparative analysis we used U-937 cells, a human monocytic/macrophage cell line. The cells were treated with transforming growth factor-beta1 (1 ng/ml) for various time periods and the levels of MMP and TIMP mRNA and protein expression were determined using quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. The results indicate that the mesothelial cells and macrophages express MMP-1 (collagenase-1), MMP-3 (stromelysin-1), TIMP-1 and TIMP-2 mRNA and protein at various levels, with significantly higher TIMPs than MMPs, and higher MMP-1 than MMP-3 (p < 0.001). The mesothelial cells express significantly less MMP-1, higher MMP- 3 and similar levels of TIMP mRNA compared to macrophages. In a time-dependent manner, treatment of the mesothelial cells with transforming growth factor-beta1 resulted in a significant decrease in the expression of MMP-1, while increasing the expression of TIMP-1 mRNA (p = 0.05). In contrast, MMP-3 and TIMP-2 expression was unaffected in mesothelial cells and in macrophages, compared to untreated controls. There was a significant increase in secreted MMP-1 and TIMP-2 by mesothelial cells following transforming growth factor-beta1 treatments in a time-dependent manner (p = 0.05 and p = 0.01), without affecting the secretion of these proteins by macrophages. A major portion of MMP-1 in the culture conditioned media of both cell types was found in complex with TIMP-1. The ratios of MMP-1/TIMPs production were significantly higher than MMP-3/TIMPs in mesothelial cells and macrophages, and progressively decreased following transforming growth factor-beta1 treatments (p < 0.05). In conclusion, these results indicate that mesothelial cells express MMP and TIMP mRNA and protein, and their expression is differentially regulated by transforming growth factor-beta1, a mechanism that in part may influence the outcome of peritoneal tissue repair and adhesion formation.

Analysis of Variance↗
PubMedDate not supplied

Matrix-enabled gene transfer for cutaneous wound repair.

Several growth factor proteins have been evaluated as therapeutic agents for the treatment of chronic dermal wounds. Unfortunately, most have failed to produce significant improvements in wound healing, in part due to ineffective delivery and poor retention in the wound defect. It has been proposed that gene therapy might overcome the limitations of protein therapy via ongoing transcription and translation, thus prolonging the availability of the therapeutic protein. Reasoning that it would be of further benefit to ensure retention of the DNA vector as well as the therapeutic protein within the wound defect, we have evaluated matrix-enabled gene transfer for cutaneous wound repair (Gene Activated Matrix). Formulations consisting of bovine type I collagen mixed with adenoviral or plasmid gene vectors have been evaluated in 3 in vivo models. The therapeutic transgenes employed encode human platelet-derived growth factor-A or -B, proteins key to each phase of normal wound repair. Increased granulation tissue formation, vascularization, and reepithelialization have been shown compared to controls treated with collagen alone or collagen containing a reporter gene vector. Further enhancements of the tissue repair response have been achieved by combining matrix-enabled gene transfer with molecular targeting, in which the DNA vector is conjugated to a growth factor ligand (basic fibroblast growth factor). These promising results support the clinical evaluation of gene activated matrices for the treatment of chronic dermal wounds.

Animals↗