Biomedical subjects

P M Sullivan

Publications and source records attributed to P M Sullivan.

At least 55 records · Page 3Linked to original sources

PubMed1996

Corticosteroids inhibit expression of inducible nitric oxide synthase during acute cardiac allograft rejection.

We have recently demonstrated that (1) nitric oxide (NO) is produced during experimental cardiac allograft rejection by the expression of inducible nitric oxide synthase (iNOS) in the rejecting organ and that (2) inhibition of NO production by iNOS attenuated acute rejection. The present study examined the interaction of corticosteroids, iNOS gene expression, and iNOS enzyme activity in a rat cardiac transplant model. Increased NO production in rejecting allografts was demonstrated by elevated serum nitrite/nitrate levels (67 +/- 5 versus 18 +/- 2 microM for isografts; P < 0.001) that were significantly reduced by pulse therapy with dexamethasone for 2 days prior to animal sacrifice or continuous dexamethasone treatment (34 +/- 2 and 19 +/- 4 microM, respectively; P < 0.001 versus untreated allografts). Increased iNOS enzyme activity was demonstrated in the allograft heart (5.11 +/- 1.00 versus 0.3 +/- 0.05 pmol L-citrulline.mg protein-1.min-1 for isografts) and was significantly reduced with dexamethasone treatment (1.13 +/- 0.47 for 2-day pulse-treated allografts and 0.02 +/- 0.01 for continuously treated allografts). Increased allograft iNOS enzyme activity resulted from induction of iNOS mRNA expression, which was more than 99% inhibited by dexamethasone treatment. Dexamethasone pulse therapy reduced but did not eliminate the histological changes of acute rejection. Thus corticosteroid treatment results in inhibition of iNOS expression during allograft rejection. These results further demonstrate that iNOS expression during acute rejection is immune-mediated and suggest that the immunosuppressive actions of corticosteroids in the treatment of acute rejection may include inhibition of iNOS expression.

Adrenal Cortex Hormones↗

PubMed1996

Distribution of immunoreactive androgen-binding protein/sex hormone-binding globulin in tissues of the fetal rat.

Androgen-binding protein/sex hormone-binding globulin (ABP/SHBG) is an extracellular carrier protein that binds androgens and estrogens with high affinity. In the adult, ABP/SHBG is thought to function in the male reproductive system and the general circulation in both sexes to modulate the actions of sex steroids. The ABP/SHBG gene is also expressed in the embryonic rat liver, where SHBG is secreted into the fetal blood of male and female rats. The embryo also expresses an alternative SHBG with a unique N-terminal sequence. In this study, the distribution of immunoreactive SHBG in the 17-day-old male fetal rat was determined with six antisera. In general, all of the antisera reacted with the same structures. Specific tissue immunoreactivity was mostly cytoplasmic and/or extracellular. By far the most prominent immunoreactive structures were the mesoderm-derived tissues: connective tissue, striated and cardiac muscle, cartilage, and the liver hematopoietic system. In addition, all regions of the fetal brain contained immunoreactive neurons. In the developing male reproductive system, there was minor reactivity in the testicular cords, whereas the connective tissue in the differentiating Wolffian duct stained with all of the antisera. The Wolffian duct epithelium and epithelia in other developing organs contained small amounts of immunoreactive SHBG, except for the lung, which stained in the epithelial extracellular matrix. An antibody raised against a unique N-terminal peptide specific for the alternative SHBG protein revealed that it was also present in many tissues. These data suggest that SHBG is important for the differentiation of mesodermal tissues. SHBG may modulate the action of androgens in embryonic stroma, thereby regulating development of the epithelium in hormone-dependent tissues.

Amino Acid Sequence↗

PubMed1996

Tyrosine kinase inhibitors prevent cytokine-induced expression of iNOS and COX-2 by human islets.

Insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease that is characterized by selective destruction of insulin-secreting beta-cells. Cytokines have been implicated as effector molecules that participate in both islet inflammation and beta-cell destruction during the development of IDDM. In this study, the effects of cytokines on the expression of inducible nitric oxide synthase (iNOS) and inducible cyclooxygenase (COX-2) by human islets were examined. In combination, the cytokines, human recombinant interleukin-1 beta (IL-1 beta), human recombinant tumor necrosis factor-alpha (TNF-alpha), and human recombinant interferon-gamma (IFN-gamma), induce the time-dependent formation of nitrite and prostaglandin E2 (PGE2) by human islets. The nitric oxide synthase inhibitor NG-monomethyl-L-arginine (L-NMMA) completely inhibits cytokine-induced nitrite formation and attenuates PGE2 production by human islets. L-NMMA does not inhibit cytokine-induced expression of COX-2 by human islets, suggesting that nitric oxide may directly activate cyclooxygenase, an effect that has been previously demonstrated for isolated rat islets. This combination of cytokines (IL-1 beta, TNF-alpha, and IFN-gamma) also induces the expression of iNOS mRNA by human islets as demonstrated by both reverse transcriptase-polymerase chain reaction and Northern blot analysis. We further show that the tyrosine kinase inhibitors genistein and herbimycin A prevent IL-1 beta plus IFN-gamma-induced expression of COX-2 and iNOS and the production of PGE2 and nitric oxide by human islets. These results demonstrate that cytokines induce the expression of iNOS and COX-2 by human islets and that cytokine-induced expression of both COX-2 and iNOS by human islets appears to require the activation of a tyrosine kinase(s).

Arginine↗

PubMed1996

Inhibition of inducible nitric oxide synthase prevents myocardial and systemic vascular barrier dysfunction during early cardiac allograft rejection.

NO is produced during cardiac allograft rejection by expression of inducible NO synthase (iNOS) in the rejecting heart. Recent evidence indicates that NO modulates vascular permeability under both physiological and pathophysiological conditions. The present study explored the effects of early acute cardiac allograft rejection, and specifically the effects of NO, on myocardial and systemic vascular barrier function using a quantitative double-tracer permeation method in a rat cardiac transplant model. Early allograft rejection increased albumin permeation twofold to fivefold in the allograft heart and systemic vasculature (brain, lung, sciatic nerve, diaphragm, retina, muscle, kidney, and uvea) compared with isografts and controls. There were no detectable differences in regional blood flow or hemodynamics, suggesting that increased albumin permeation resulted from increased vascular permeability. iNOS mRNA was expressed in the allograft heart and native lung and was associated with increased serum nitrite/nitrate levels. iNOS inhibition with aminoguanidine prevented or attenuated allograft heart and systemic vascular barrier dysfunction and reduced allograft serum nitrite/nitrate levels to isograft values. Aminoguanidine did not affect the mild histological changes of rejection present in allografts. These data demonstrate the novel observations that (1) endothelial barrier function is compromised in the systemic vasculature, particularly in the brain, remote from the site of allograft rejection; (2) allograft vascular barrier dysfunction is associated with increased NO production and iNOS mRNA expression in the affected tissues (eg, native lung and grafted heart); and (3) inhibition of NO production by iNOS prevents vascular barrier dysfunction in the allograft heart and systemic vasculature.

Animals↗

PubMed1996

Inhibition of inducible nitric oxide synthase attenuates established acute cardiac allograft rejection.

BACKGROUND: We previously demonstrated that continuous treatment with aminoguanidine, a selective inhibitor of nitric oxide production by inducible nitric oxide synthase, attenuated acute cardiac allograft rejection. METHODS: A rat transplant model was used to determine (1) when inducible nitric oxide synthase was expressed in the allograft heart during unmodified acute rejection and (2) whether pulse therapy with aminoguanidine attenuated the histologic changes of established acute rejection, in comparison with the effects of pulse therapy with corticosteroids. RESULTS: Inducible nitric oxide synthase messenger RNA and protein were expressed during early and late acute rejection. Pulse therapy with aminoguanidine inhibited nitric oxide production and attenuated the histologic changes of acute rejection, but not as effectively as corticosteroid therapy (rejection scores of 4.1 +/- 0.4, 2.5 +/- 0.9, and 1.4 +/- 0.6 on postoperative day 8, for untreated, aminoguanidine-, and dexamethasone-treated allografts, respectively (scale, 0 to 5; p < 0.05). CONCLUSIONS: (1) Inducible nitric oxide synthase expression first occurs during early acute allograft rejection and persists throughout rejection and (2) nitric oxide is an important effector molecule in acute rejection. Inducible nitric oxide synthase inhibition may offer a therapeutic adjunct in the management of acute rejection.

Animals↗

PubMed1995

Lead, chromium, and cadmium emission factors during abrasive blasting operations by bridge painters.

Work space airborne concentrations of lead, chromium, and cadmium were measured during abrasive blasting by bridge painters for the determination of emission rates. The operation used compressed air to blast steel grit at steel or metal surfaces, removing lead-based paint. It was enclosed with plastic tarpaulins to prevent the release of lead- and chromium-laden dust. Consequently, workers were at increased risk from exposure by inhalation or ingestion. Area samples were collected in 13 contained work areas on a 4-leaf bridge and adjacent viaduct while blasting was performed. Enclosure volume and exhaust air flow rate were measured for each containment area. Work space airborne concentrations ranged from 196-31,410 micrograms/m3 for lead, 1-657 micrograms/m3 for chromium, and 1-19 micrograms/m3 for cadmium. Mass balance models were used to calculate emission rates and emission factors using the measured area concentrations. Average emission factors on the bridge were 20,400 mg/m2 for lead, 75 mg/m2 for chromium, and 16 mg/m2 for cadmium; and on the viaduct were 8790 mg/m2 for lead, 568 mg/m2 for chromium, and 2.0 mg/m2 for cadmium. These values were validated using estimates of total paint volume and composition on the structure and total waste generation. All estimates were within 50% of each other except chromium estimates for the bridge. The emission factors allow prediction of work space airborne concentrations during similar operations and are a first step in the design and implementation of control measures.

Air Pollutants, Occupational↗

PubMed1995

Results of cemented femoral revision total hip arthroplasty using improved cementing techniques.

Seventy-nine consecutive femoral component revision total hip arthroplasties done in 73 patients from 1977 to 1983 using a distal intramedullary cement plug and a cement gun delivery system were evaluated to determine if improved results were obtained with newer cementing techniques. At a minimum 10-year followup interval, only 1 patient was not available for followup and 47 hips had minimum 10-year followup radiographs. The incidence of femoral rerevision for aseptic loosening was 9.5% for those hips with minimum 10-year followup and 5.4% for the entire group. The incidence of radiographic femoral failure (defined as a revision or definite or probable loosening) was 26.1% for those hips followed for a minimum of 10 years and 16.3% for the entire group. Compared with historical controls, these results represent an improvement over those reported with the use of earlier cementing techniques.

Adult↗

PubMed1994

Hearing research career development for deaf students.

One goal of the Americans with Disabilities Act is to enhance access to career opportunities for individuals with hearing loss. Hearing-impaired professionals are woefully underrepresented among the cadre of scientists currently involved in hearing and deafness research. Information was obtained by questionnaire from 190 consecutive attendees (13 through 17 years of age) at a summer program for gifted hearing-impaired adolescents regarding career goals, attitudes toward academic and extracurricular activities, educational placement, primary communication modality, and parental hearing status. A follow-up questionnaire completed by 80 of these youth, presently attending college, provided comparison data regarding type of college attended and academic major. Males were significantly more likely to select majors in mathematics and science-related disciplines. The percentage of college attendees majoring in the sciences was much lower than the percentage of high school students who aspired to a scientific career. Strategies for attracting qualified hearing-impaired students into science majors should include educational efforts directed at students, parents, and academic advisors.

Adolescent↗

PubMed1994

Total hip arthroplasty with cement in patients who are less than fifty years old. A sixteen to twenty-two-year follow-up study.

Eighty-nine Charnley total hip arthroplasties were performed with cement, by a single surgeon, in sixty-seven patients who were less than fifty years old at the time of the procedure. The follow-up period ranged from sixteen to twenty-two years (average, eighteen years). The most recent evaluation consisted of a clinical and a radiographic examination for forty-six patients (fifty-eight hips), a telephone interview and a review of the most recent radiographs for eleven patients (sixteen hips), and a telephone interview only for six patients (ten hips). Four patients (five hips) were lost to follow-up. Eleven (13 per cent) of the eighty-four hips that were followed were revised because of aseptic loosening of the acetabular implant, and two hips (2 per cent) were revised because of aseptic failure (loosening or fracture) of the femoral component. When the number of hips that were revised was combined with the number of hips in which there was radiographic evidence of failure, the rate of loosening of the acetabular component was 50 per cent (forty-two hips) and the rate of failure of the femoral component was 8 per cent (seven hips). Three hips had recurrent dislocations after the operation; none of the three was revised. One patient (two hips) had Grade-III heterotopic ossification according to the system of Brooker et al.; no other patient had more than Grade-II heterotopic ossification. Nine hips had a trochanteric non-union without migration of the trochanter.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetabulum↗

PubMed1994

The results of improved cementing techniques for total hip arthroplasty in patients less than fifty years old. A ten-year follow-up study.

Thirty-six patients (forty-two hips) in whom so-called second-generation cementing techniques, such as medullary lavage, use of an intramedullary cement plug, hand-mixing of the cement, and use of a cement gun to deliver the cement in a doughy state in a retrograde fashion, had been used for a primary total hip arthroplasty were evaluated at an average of eleven years (range, ten to fifteen years) after the operation. All of the patients had been less than fifty years old at the time of the operation. Thirty-one patients were evaluated by clinical and radiographic examinations and five, by a telephone interview. Twelve components (ten acetabular components [24 per cent] and two femoral components [5 per cent]) in ten hips had been revised for aseptic loosening. An additional five acetabular components (12 per cent) and five femoral components were definitely loose according to radiographic criteria. Three of these femoral components were polished stems that were considered loose only because of the presence of a radiolucent line, 0.5, one, and two millimeters wide, at the prosthesis-cement interface in zone 1 of Gruen et al. The other two loose stems were in patients who were receiving renal dialysis. These findings demonstrate excellent fixation of the femoral component but continued problems with fixation of the acetabular component despite the use of improved cementing techniques.

Activities of Daily Living↗

PubMed1993

High-level expression and purification of human leukotriene A4 hydrolase from insect cells infected with a baculovirus vector.

Leukotrienes constitute a group of bioactive compounds derived from arachidonic acid which play important roles in immediate hypersensitivity and inflammation. Leukotriene A4 hydrolase (LTA4H) is an epoxide hydrolase, catalyzing the hydration of LTA4 to LTB4, and also acts an aminopeptidase, with the ability to cleave amides of p-nitroaniline. The cDNA for LTA4H was cloned using oligonucleotide-directed amplification of the cDNA sequence by polymerase chain reaction and by oligonucleotide-based screening of a bacteriophage lambda gt11 cDNA library derived from human placental tissue. High levels of biologically active LTA4H were expressed in cultured Spodoptera frugiperda insect cells infected with a baculovirus expression vector containing the LTA4H cDNA. Expression levels were approximately 100 mg per liter of cell-free culture media. LTA4H was recovered from the medium and purified to > 95% purity by ion-exchange and gel-filtration chromatography, with an overall yield of 76%. LTA4H produced by insect cells exhibits both hydrolase and aminopeptidase activities and has kinetic properties similar to those reported for enzyme isolated from human lung. Two major isoforms, with pI's of 5.3 and 5.1, were isolated by preparative chromatofocusing chromatography. NH2-terminal sequence analysis revealed that the two different by an NH2-terminal blocking group. Electrospray ionization mass spectrometry indicates that the two isoforms differ by a molecular mass of 42, indicating that the blocking group is an acetyl group.

Acetylation↗

PubMed1993

Tissue-specific expression of the rat androgen-binding protein/sex hormone-binding globulin gene in transgenic mice.

The testicular Sertoli cell produces an extracellular androgen-binding protein (ABP) that binds testosterone and dihydrotestosterone with high affinity. The ABP gene also encodes plasma sex hormone-binding globulin (SHBG), which is produced by the liver of most species. Unlike the human, adult rats and mice do not express SHBG. A 5.5-kb rat genomic DNA fragment was found to contain the entire coding regions of ABP and 1.5 kb upstream of the transcription start site. To aid in identification of the promoter and enhancer regions of the ABP/SHBG gene, we developed transgenic mice that express the rat gene. The 5.5-kb DNA was microinjected into the pronuclei of fertilized mice ova, which were transferred to the reproductive tract of pseudopregnant females. Three of the offspring were identified as carriers of the rat gene by Southern hybridization and these founders were bred with normal mice to establish heterozygous transgenic lines. Northern blot analysis, RNA-PCR and sequencing of the PCR products from the adult transgenic mice revealed extremely high levels of the rat ABP mRNA in the testis, but no detectable rat ABP mRNA in liver, kidney or brain. Primer extension experiments showed that the correct transcript ion start site is utilized in the transgenes. These data demonstrate that the 5.5-kb genomic DNA fragment contains an element(s) capable of directing ABP gene expression in the testis. This enhancer should prove useful for the targeting of specific gene products to the mature Sertoli cell in transgenic animals.

Androgen-Binding Protein↗

PubMed1993

Patient satisfaction following vitreoretinal surgery.

A postal questionnaire was used to study patient satisfaction in 149 consecutive patients undergoing vitreoretinal surgery in Southampton. Of the 123 patients who responded, 70 (60%) felt that their vision improved following surgery. Fifty-eight patients (47%) stated that their vision was not as good as they had hoped it would be, and multiple logistic regression analysis showed that this response reflected a poorer visual outcome in this group. Despite this, 116 (94%) of those replying stated that the operation had been worth while. All 5 patients who felt that their operations had not been worth while had undergone retinal detachment surgery. This high level of satisfaction may be attributable to realistic expectations, as 116 patients (94%) replied that the procedures had been adequately explained.

Adult↗

PubMed1993

Identification of an alternate promoter in the rat androgen-binding protein/sex hormone-binding globulin gene that regulates synthesis of a messenger RNA encoding a protein with altered function.

Extracellular androgen-binding proteins (ABP) are thought to modulate the regulatory functions of androgens. These proteins, which are secreted by the testis (ABP) and liver [sex hormone-binding globulin (SHBG)], are encoded by the same gene. In a previous study, the rat ABP/SHBG gene was sequenced, and a promoter (P1) was identified by primer extension. This promoter regulates synthesis of the mRNA that encodes secreted testicular ABP and fetal liver SHBG. In this study, the P1 transcriptional start site in testis and fetal liver was confirmed by RNase protection assays. We also identified an alternate promoter (PA) in the ABP/SHBG gene located 15 kilobases up-stream from the previously characterized testicular promoter (P1). The PA region has the characteristics of a GC-rich housekeeping-type promoter. RNAase protection and primer walking experiments with RNA polymerase chain reaction identified a region where the major sites of transcription initiation occur. Promoter PA directs the synthesis of alternate ABP RNAs, which contain an alternate exon 1 (exon A) sequence. One alternate ABP RNA, which contains exons A and 2-8 sequences, is expressed in testis, fetal liver, and brain. This alternate ABP RNA encodes an ABP-like protein (46,000 daltons) with an altered N-terminal sequence without a secretory signal peptide. Expression of the ABP-like protein in COS cells revealed that it is not secreted and does not appear to bind dihydrotestosterone. Another similar alternate ABP RNA is missing exon 6 sequence and encodes a nonsecretory truncated protein (28,000 daltons) that does not bind androgen. The functions of the ABP-like proteins are not obvious, but their functions are clearly different from secreted ABP and SHBG.

Amino Acid Sequence↗

PubMed1992

Retinal vessel measurement: comparison between observer and computer driven methods.

A method of semi-automated image analysis for the measurement of retinal vessel diameters is described. This was compared with an observer-driven method for reproducibility and accuracy. The coefficient of variation for the data from the semi-automated method was 1.5-7.5% (depending on the vessel diameter) compared to 6-34% with the observer-driven method. The mean vessel diameters using the observer-driven method tended to be higher; however, this did not reach significance. The speed and low inter- and intra-observer variability for the semi-automated method make it a useful technique for measuring retinal blood vessel diameters. A larger variability was found between photographs taken at different times. This may be due to changes in retinal vessel diameter with changes in retinal perfusion pressure during the cardiac cycle.

Diabetic Retinopathy↗

PubMed1992

The effects of psychotherapy on behavior problems of sexually abused deaf children.

This study assessed the effectiveness of a broad based psychotherapeutic intervention with a sample of 72 children sexually abused at a residential school for the deaf. An untreated comparison group emerged when about half of their parents refused the offer for psychotherapy provided by the school. Treated and untreated children were randomly assigned to two assessment groups: those who participated in a pretreatment assessment and those who did not. Houseparents at the residential school used the Child Behavior Checklist (CBC) to rate the pretreatment assessment children before treatment and all 72 children one year after the implementation of psychotherapy. Children receiving therapy had significantly fewer behavior problems than children not receiving therapy. There was a differential response to therapy on the basis of sex. Boys receiving therapy had significantly lower scores on the following CBC scales than the no treatment group: Total, Internal, External, Somatic, Uncommunicative, Immature, Hostile, Delinquent, Aggressive, and Hyperactive. There were no differences on the Schizoid and Obsessive scales. Girls receiving therapy had significantly lower scores than the no treatment group on the following CBC scales: Total, External, Depressed, Aggressive, and Cruel. There were no differences on the Internal, Anxious, Schizoid, Immature, Somatic, and Delinquent scales.

Adolescent↗

PubMed1992

Validation and reproducibility of bidirectional laser Doppler velocimetry for the measurement of retinal blood flow.

Bidirectional laser Doppler velocimetry (BLDV) for the measurement of retinal blood flow was validated in six anaesthetised minipigs, by comparing BLDV derived results with those obtained using radioactively labelled microspheres (RLM). The mean velocity of blood (Vmean) was calculated from the maximum red blood cell velocity measured by BLDV. Volumetric flow rate was determined from Vmean and vessel diameter, measure from monochromatic fundus photographs. Total retinal blood flow (TRBF) was calculated by summating flow values obtained for each retinal vein draining into the optic disc. A significant correlation was found between the TRBF results obtained by the two techniques (r = 0.99, p less than 0.001). The BLDV results were between 3-35 microliters/min lower than the corresponding RLM results (p = 0.05). Values of 57 +/- 24 microliters/min and 76 +/- 34 microliters/min were obtained for TRBF using the BLDV and RLM techniques respectively. Reproducibility studies with BLDV were also performed in six anaesthetised pigs over three hours and in six normal human volunteers over two hours and two weeks. No significant difference between measurements was found with time. Ninety five percent confidence limits of +/- 9.8% for the six pigs and +/- 8.9% for the six human volunteers were found for measurements on the same day and at two weeks. We conclude that with a sample size of six, changes in flow of approximately 20% can be detected using BLDV and monochromatic fundus photography.

Adult↗

PubMed1991

Alternative processing of androgen-binding protein RNA transcripts in fetal rat liver. Identification of a transcript formed by trans splicing.

Androgens and their nuclear receptor regulate genes necessary for development of the male phenotype, a process that is thought to be modulated by extracellular androgen carrier proteins. Two of these carrier proteins, testicular androgen-binding protein (ABP) and plasma sex hormone-binding globulin (SHBG), are encoded by the same gene, but differ in glycosylation and possibly amino acid sequence. To investigate ABP-SHBG gene expression in fetal rat liver, we analyzed RNA transcripts and expressed protein. These studies demonstrated a transient expression of ABP in hepatocytes during the time of testosterone-dependent differentiation of the Wolffian duct. Analysis of cDNA clones derived from fetal rat liver cDNA libraries identified two cDNAs encoded by the ABP-SHBG gene that represented alternatively spliced RNAs. One cDNA had an alternate exon 1, suggesting the function of another promoter in fetal liver. This cDNA also lacked testicular exon 6 DNA, an alteration that implicates the encoded protein in regulatory functions. The other cDNA represented a fused transcript of the ABP-SHBG gene (exons 1-5) and the histidine decarboxylase (HDC) gene, encoding a Mr 98,000 precursor protein. The two domains were joined at splice junctions of the ABP-SHBG and HDC genes, which were localized to rat chromosomes 10 and 3, respectively. Our results indicate that the joining of the two domains was by a trans (donor and acceptor)-splicing mechanism. Data from Northern hybridization experiments suggest the fusion transcript is present in fetal liver RNA. Polymerase chain reaction experiments with fetal liver cDNA further support the existence of an ABP-HDC fusion transcript, as well as the other alternate mRNA. Moreover, a Mr 93,000 immunoreactive protein was transiently expressed in fetal liver during the time of ABP and HDC gene expression. Expression of the fusion cDNA in COS cells yielded HDC activity and the predicted size protein (Mr = 93,000) on Western immunoblots.

Amino Acid Sequence↗