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Biomedical subjects

J Paulson

Publications and source records attributed to J Paulson.

At least 19 recordsLinked to original sources
PubMed2005

Tau suppression in a neurodegenerative mouse model improves memory function.

Neurofibrillary tangles (NFTs) are the most common intraneuronal inclusion in the brains of patients with neurodegenerative diseases and have been implicated in mediating neuronal death and cognitive deficits. Here, we found that mice expressing a repressible human tau variant developed progressive age-related NFTs, neuronal loss, and behavioral impairments. After the suppression of transgenic tau, memory function recovered, and neuron numbers stabilized, but to our surprise, NFTs continued to accumulate. Thus, NFTs are not sufficient to cause cognitive decline or neuronal death in this model of tauopathy.

Aging↗
PubMed2000

Evaluation of poly(acrylic acid-co-ethylhexyl acrylate) films for mucoadhesive transbuccal drug delivery: factors affecting the force of mucoadhesion.

Based on the premise that similar surface properties between the adhesive and the substrate would yield a strong adhesive bond, copolymers of acrylic acid (AA) and 2-ethylhexyl acrylate (EHA), P(AA-co-EHA), were designed and synthesized for buccal mucoadhesion. A series of linear copolymers with varying feed ratios of the two monomers (AA and EHA) were synthesized through free radical copolymerization at 69+/-0.5 degrees C using azobis(isobutyronitrile) (AIBN) as initiator. The reactions were carried out in THF under nitrogen for 24 h. The glass transition temperatures, T(g), of the copolymers were determined using DSC. The adhesion studies were conducted to determine the effects of copolymer composition, contact time between the substrate and the adhesive, and crosshead speed on mucoadhesive performance of the copolymer films using a computer interfaced Instron material testing system. The glass transition temperature of the copolymers decreased with increasing EHA content. Wet glass surface as substrate was shown not to be a good substrate model for adhesion determination studies. The copolymer composed of 46:54 mol.% AA:EHA (an almost 1:1 ratio in the repeat units) yielded the highest mucoadhesive force in contact with porcine buccal mucosa which was significantly greater (P<0.05) than that of poly(acrylic acid) (PAA) (used as positive control). The mucoadhesive force for all copolymers studied was significantly (P<0.05) greater than that of the negative control (backing material without copolymer film) except for the EHA homopolymer. Crosshead speed increased mucoadhesive force linearly and had a more pronounced effect on the mucoadhesive performance than time of contact between the adhesive and the substrate.

Acrylates↗
PubMed2000

Linear PADRE T helper epitope and carbohydrate B cell epitope conjugates induce specific high titer IgG antibody responses.

Linear carbohydrate-peptide constructs based on the 13 amino acid nonnatural pan DR epitope (PADRE) and carbohydrate B cell epitopes are demonstrated to be potent immunogens. These data support our belief that PADRE should be considered as an alternative to more complex carriers for use in prophylaxis and therapeutic vaccines. Two model carbohydrate-PADRE glycoconjugates were used to demonstrate that PADRE could effectively provide T cell help for carbohydrate-specific Ab responses. Conjugates of PADRE covalently linked to the human milk oligosaccharide, lacto-N-fucopentose II or a dodecasaccharide derived from Salmonella typhimurium O-Ag induced high titer IgG Ab responses in mice, which were comparable to glycoconjugates employing human serum albumin (HSA) as the carrier protein. Different adjuvants, in combination with PADRE conjugates, allowed for the modulation of the isotype profile with alum supporting an IgG1 profile; QS-21 an IgG2a, 2b profile, while an alum/QS-21 mixture generated a balanced IgG1/IgG2b isotype profile. As defined by binding to synthetic glycoconjugates, dodecasaccharide-specific Abs exhibited fine specificity similar to protective polyclonal Ab responses previously reported for dodecasaccharide-protein conjugates. The same Abs bound to intact S. typhimurium cells, suggesting that biologically relevant specificities were produced. The affinity of the dodecasaccharide-specific Abs was further shown to be comparable to that of a well-characterized, high affinity monoclonal anti-carbohydrate Ab recognizing the same epitope.

Adjuvants, Immunologic↗
PubMed2000

Phase II study of mifepristone (RU486) in refractory ovarian cancer.

OBJECTIVE: A phase II study of Mifepristone (RU486) was conducted in patients with ovarian cancer whose tumors were resistant to cisplatin and paclitaxel, alone or in combination. PATIENTS AND METHODS: Forty-four patients were accrued into this study. All had ovarian cancer that had become resistant to cisplatin and paclitaxel. Patients received Mifepristone 200 mg orally on a daily basis. Patients were followed by tumor size or CA-125 levels when there was no measurable disease. A dose reduction of Mifepristone was to occur in the event of grade 3/4 hematologic, GI, or liver toxicity, creatinine >2.5%, and grade 4 peripheral neuropathy. RESULTS: Thirty-four patients were evaluable for response. Nine (26.5%) of these patients had a response to Mifepristone. Three(9%) patients had a complete response, and six (17.5%), a partial response. The response of one patient in each group was measured by CA-125 levels while the remainder had measurable disease. The response lasted 1 to 4 months in all but one patient. One patient continues to respond after more than 3 years. The major toxic effect was a rash and this was the major reason patients were removed from the study. CONCLUSION: Mifepristone has activity against ovarian cancer resistant to cisplatin and paclitaxel. The drug is well tolerated. Further studies need to be performed when this drug becomes more widely available in the United States.

Adult↗
PubMed1999

Failure to diagnose hereditary colorectal cancer and its medicolegal implications: a hereditary nonpolyposis colorectal cancer case.

PURPOSE: We describe a patient who had precancerous colonic symptoms and a positive family history of multiple occurrences of early-onset colorectal cancer in her first-degree and second-degree relatives consistent with hereditary nonpolyposis colorectal cancer. Hereditary nonpolyposis colorectal cancer diagnosis had not been made before her diagnosis of carcinoma of the cecum with liver metastasis. She died at age 20, leading to litigation. Controversies about standards of care, their malpractice implications, and pertinent legal issues are discussed. METHODS: Review of the medical and family history was made by the expert witness (HTL) with appropriate documentation of the chronology of symptoms, as derived from depositions. These documents revealed that the patient's mother had repeatedly discussed with the caregivers her concern about the family history of colon cancer and the need for appropriate surveillance. RESULTS: The patient's colonic symptoms progressed for a period of three years. Flexible sigmoidoscopy was performed by a nonphysician. The physician who ordered the procedure considered this appropriate because isolated polyps were reported in the patient's father and paternal uncle, which apparently led him to believe that the diagnosis was familial adenomatous polyposis. During litigation procedures, a pedigree was constructed and found to be consistent with hereditary nonpolyposis colorectal cancer. The case was settled in favor of the plaintiff before trial. CONCLUSION: It is essential to understand the natural history of hereditary nonpolyposis colorectal cancer, inclusive of the need for surveillance colonoscopy in patients at increased risk by virtue of their position in their family pedigree.

Adenomatous Polyposis Coli↗
PubMed1997

Pharmacokinetics and systemic effects of inhaled fluticasone propionate in healthy subjects.

AIMS: The present study was undertaken to see whether the difference in plasma cortisol suppression between single and repeated dosing of fluticasone propionate (FP) can be explained by systemic accumulation. METHODS: Twelve healthy subjects (six women) were given, in a crossover fashion, a single dose inhalation (1000 micrograms) of FP via Diskhaler and repeated inhalations (1000 micrograms twice daily) every 12 h during 7 days. There was a washout period of 2 weeks between the treatments. An intravenous dose of 20 micrograms FP was given as a reference. Plasma concentrations of FP for each treatment were determined by liquid chromatography plus tandem mass spectrometry. Plasma cortisol after the inhaled doses was determined using an immunoassay and was compared with baseline values. RESULTS: The average plasma concentration of FP was about 1.7 times higher after multiple inhalations than after a single dose. Systemic availability, mainly attributable to pulmonary deposition, was 15.6 [13.6-18.0]% of the nominal dose. Daytime plasma cortisol suppression vs baseline was 47 [20-65]% and 95 [93-97]% for the single and repeated doses, respectivley. CONCLUSIONS: To conclude, a slow elimination of FP leads to accumulation during repeated dosing. This accumulation may explain the marked decrease in plasma cortisol seen during treatment with fluticasone propionate within the clinical dose range.

Administration, Inhalation↗
PubMed1996

Mortality pattern among biological research laboratory workers.

A cohort study was conducted to investigate the mortality of individuals employed by biological research institutes in the UK. The inclusion criteria were met by 12,703 individuals, of whom 95% were traced (11,502 alive, 395 deaths, 246 embarkations). All-cause mortality was significantly reduced in men (standardised) mortality ratio (SMR) 55 and women (SMR 52). Mortality was also significantly reduced for circulatory and respiratory diseases, and overall there was low mortality from malignant neoplasms. SMRs exceeded 100, but were not statistically significant, for infective and parasitic diseases. There were no statistically significant raised SMRs for any cancer site. Workers were categorised as ever worked in a laboratory (laboratory workers) and never worked in a laboratory (non-laboratory workers). The all-cause SMR was significantly reduced in both groups, as was mortality from circulatory and respiratory diseases. The SMR for malignant neoplams was also significantly reduced in laboratory workers. On the basis of follow-up to 31 December 1994, there is no evidence of any overall increased risk of mortality in biological research laboratory workers. However, the power of the analysis is limited by the young age of many cohort members and short duration of follow-up. Follow-up is continuing and the data will be reanalysed once more deaths have accumulated.

Agriculture↗
PubMed1995

Adolescent Injury Prevention in Primary Care.

Primary care providers, on the frontline of health care delivery, have an opportunity to see adolescents in the office or clinic and to provide counseling that can reduce injuries among adolescents. After an initial discussion on the barriers to such efforts, the authors offer a framework for the role of primary care clinicians in injury prevention, with practical guidelines for implementing counseling in practice. The authors also provide extensive information on resources available to improve skills in this area and for referring patients who need additional counseling or management, and they urge that providers participate in community activities related to injury prevention.

Journal Article↗
PubMed1994

Neuromelanin of the human substantia nigra: a mixed-type melanin.

Model melanins, synthesized with different cysteinyldopamine/dopamine ratios in the incubates, were oxidized with KMnO4 and the resulting compounds were analyzed by HPLC. The ratios between a phaeomelanin-derived compound, thiazole-4,5-dicarboxylic acid (TDCA), and a compound derived from eumelanin, pyrrole-2,3,5-tricarboxylic acid (PTCA), reflected the composition of the model melanins. The neuromelanin of the human substantia nigra was isolated, and the pigment, as well as intact brain tissue from human substantia nigra was oxidized with KMnO4 and the TDCA/PTCA ratios were determined. Analysis of the isolated neuromelanin showed it to contain 2.3% sulfur and 8.1% nitrogen. The sulfur content indicates the pigment is a mixed-type melanin, and the TDCA/PTCA ratio indicates that it consists of units derived from benzothiazines and from indoles in about equal amounts.

Autopsy↗
PubMed1994

Melanins in IGR 1 melanoma cells.

Information on the composition of melanins is obtained by analysis both of 4-amino-3-hydroxyphenylalanine (AHP) after hydriodic acid degradation and of pyrrole-2,3,5-tricarboxylic acid (PTCA) after potassium permanganate oxidation. Analysis of thiazole-4,5-dicarboxylic acid (TDCA) and pyrrole-2,3-dicarboxylic acid (PDCA) after permanganate oxidation, provides additional information on the composition, TDCA on pheomelanin residues, and PDCA on indolic residues without carboxy groups. Using model melanins formed from dopa and cysteinyldopa in different proportions, we found the TDCA/(PTCA+PDCA) ratio to yield a reliable estimate of the relative proportions of pheomelanin and eumelanin. The PDCA/PTCA ratio reflects the relationship between indole residues with and without carboxy groups. We have analyzed degradation products from cultures of IGR 1, an extensively studied melanoma cell line. Cell cultures were harvested after 2, 4, and 7 days. Culture media were changed after 2 days in all series, and also after 4 days in one series harvested at 7 days. Cells without medium change had seven times the amount of melanin found in cultures with medium change. The PDCA/PTCA ratio decreased with increasing amounts of melanin. With increased melanization, eumelanin is increased relatively more than pheomelanin. The cell content of 5-S-cysteinyldopa (5-S-CD) was similar in all cultures, while 6-hydroxy-5-methoxyindole-2-carboxylic acid (6H5MICA), a eumelanin precursor metabolite, was found in increased amounts of media of heavily pigmented cultures.

Chromatography, Liquid↗
PubMed1994

Sialyl Lewisx-containing oligosaccharide exerts beneficial effects in murine traumatic shock.

We investigated the effects of a soluble sialyl Lewisx-containing oligosaccharide (SLex-OS) in a rat model of traumatic shock. Pentobarbital-anesthetized rats subjected to Noble-Collip drum trauma developed a shock state characterized by marked hypotension, a survival time of 85 +/- 15 min, significant increases in ileal myeloperoxidase (P < 0.01), and plasma free amino-nitrogen activities (P < 0.01). Treatment with SLex-OS (10 mg/kg) 10 min posttrauma prolonged survival time to 198 +/- 29 min (P < 0.01), significantly attenuated ileal myeloperoxidase activity (P < 0.01), and diminished the accumulation of plasma free amino-nitrogen (P < 0.01), drug vs. vehicle, respectively. Furthermore, endothelium-dependent relaxation to acetylcholine in superior mesenteric artery rings isolated from SLex-OS-treated shock rats was significantly preserved (70 +/- 6 vs. 40 +/- 5% relaxation). No beneficial effects were observed using a nonfucosylated control oligosaccharide. Moreover, addition of SLex-OS significantly inhibited unstimulated human polymorphonuclear neutrophil (PMN) adherence in vitro to trauma-activated superior mesenteric artery endothelium ex vivo (P < 0.001). Our results indicate that SLex-OS exerts beneficial effects in traumatic shock states by blocking selectin-mediated leukocyte-endothelium interaction, thus improving survival, attenuating intestinal PMN accumulation, and diminishing shock-induced tissue injury.

Animals↗
PubMed1993

Protective effects of sialylated oligosaccharides in immune complex-induced acute lung injury.

Using sialyl Lewisx (SLX) oligosaccharides derived from fucosyl transferase-expressing cells or generated synthetically, the ability of these compounds to protect against acute lung damage after deposition of immunoglobulin (Ig)G or IgA immune complexes has been determined. The synthetic compounds were tetra- and pentasaccharide derivates of SLX as well as the nonfucosylated forms of SLX as controls. In the IgG immune complex model of lung injury, which is E-selectin dependent, SLX preparations provided dose-dependent protective effects, as assessed by changes in lung vascular permeability and hemorrhage. Protective effects were associated with diminished tissue accumulation of neutrophils in lungs (as assessed by myeloperoxidase). Morphological assessment revealed reduced physical contact of neutrophils with the pulmonary vascular endothelium and reduced tissue accumulation of neutrophils. In the model of IgA immune complex-induced lung injury, which does not involve participation of neutrophils and is independent of the requirement for E-selectin, SLX preparations were not protective. These data suggest that, in neutrophil-mediated and E-selectin-dependent lung injury, SLX preparations provide significant, protective effects against inflammatory vascular injury. The ability to achieve antiinflammatory outcomes in vivo with appropriate oligosaccharides suggests a new approach to the blocking of acute inflammatory responses.

Acute Disease↗
PubMed1993

Role of endothelial adhesion molecules in NSAID-induced gastric mucosal injury.

A number of recent studies have demonstrated that neutrophil adherence to the vascular endothelium is a critical early event in the pathogenesis of gastric mucosal injury induced by nonsteroidal anti-inflammatory drugs (NSAIDs). Although a role in this process for the leukocyte adhesion molecule, CD11/CD18, has been demonstrated, the involvement of endothelial adhesion molecules has not previously been examined. Therefore, using monoclonal antibodies directed against a number of endothelial adhesion molecules (ICAM-1, P-selectin, E-selectin), we studied the role of these molecules in the production of mucosal injury after indomethacin administration and in indomethacin-induced leukocyte adherence. As previously shown in the rabbit, anti-CD18 markedly reduced (by 75%) the severity of damage induced by indomethacin in the rat. Moreover, this antibody completely prevented indomethacin-induced leukocyte adherence. Similarly, anti-ICAM-1 significantly attenuated (by 74%) the severity of indomethacin-induced gastric injury while also markedly reducing leukocyte adherence (by 83%). Anti-P-selectin and anti-E-selectin produced only small (approximately 35%), but statistically significant, reductions of mucosal injury, but only anti-P-selectin significantly affected indomethacin-induced leukocyte adherence (by approximately 50%). These results demonstrate that indomethacin-induced leukocyte adherence and mucosal injury are dependent on the expression of CD18 and ICAM-1. P-selectin also appears to play a small, but important, role in these processes, whereas the role of E-selectin remains equivocal. These studies support the hypothesis that interactions at the leukocyte-endothelium interface are critical in the pathogenesis of NSAID-induced mucosal injury, and this interface may represent a rational target for therapies aimed at preventing this form of injury.

Animals↗
PubMed1993

Inhibition of nitric oxide production. Mechanisms of vascular albumin leakage.

The mechanisms by which nitric oxide modulates microvascular albumin exchange were investigated by monitoring leukocyte-endothelial cell adhesion and fluorescein isothiocyanate-albumin leakage in rat mesenteric venules exposed to NG-nitro-L-arginine methyl ester (L-NAME). L-NAME elicited an initial rapid increase followed by a slower rate of albumin accumulation in the interstitial space. The initial phase of albumin leakage preceded the L-NAME-induced leukocyte adherence and emigration, whereas the magnitude of the albumin leakage observed in the later phase of L-NAME exposure was highly correlated with the number of adherent and emigrated leukocytes in the same segment of venule. Monoclonal antibodies (MAbs) directed against adhesion molecules CD11/CD18, ICAM-1, or P-selectin, but not a nonbinding MAb, attenuated the albumin leakage induced by L-NAME. WEB2086, a platelet activating factor antagonist, and 8-bromoguanosine 3',5'-cyclic monophosphate (8-br-cGMP) reduced the leukocyte adherence and emigration as well as the increased albumin leakage. Only 8-br-cGMP and the P-selectin MAb attenuated the platelet-leukocyte aggregation elicited by L-NAME. Phalloidin, which promotes endothelial junctional integrity, inhibited both the early and late phases of albumin leakage. Overall, these findings suggest that the increased albumin leakage observed in postcapillary venules after inhibition of nitric oxide production involves a mechanism that includes a role for cGMP, platelet activating factor, leukocyte-endothelial cell adhesion, and the endothelial cell cytoskeleton.

Albumins↗
PubMed1992

Determination of (22R,S)budesonide in human plasma by automated liquid chromatography/thermospray mass spectrometry.

(22R,S)Budesonide was isolated from human plasma by solid-phase extraction. Switching from reversed-phase conditions during sample application and washing to normal-phase conditions during elution afforded a very clean extract. Budesonide was derivatized with acetic anhydride to form the 21-acetyl derivative before analysis by reversed-phase liquid chromatography combined with thermospray mass spectrometry. Deuterium-labelled budesonide was used as internal standard. Standard samples prepared in human albumin solution were used for the calibration curve. An automated liquid chromatography/mass spectrometry system, allowing unattended overnight operation, was used for routine analysis. The recovery of budesonide from plasma was 88.9 +/- 5.9% (mean +/- SD) and the method was linear over the range 0.30-30 pmol (amount analysed), corresponding to plasma concentrations of 0.10-10 nmol l-1. Budesonide could be measured down to 0.10 nmol l-1 with a within-day variation of 10-18% (CV). The error was less than +/- 15% at 0.10 nmol l-1 and less than +/- 7% at concentrations of 0.20 nmol l-1 or higher. The total imprecision between days was 9% (CV) at a concentration of 0.30 nmol l-1.

Administration, Topical↗
PubMed1991

Increasing thermospray response for cortisol by derivatization.

The 21-hydroxyl group of cortisol was selectively acetylated under mild conditions without affecting the more sterically hindered 11 beta- and 17 alpha-hydroxyl groups. The reaction was performed with a mixture of acetic anhydride and triethylamine in acetonitrile and was complete in less than 15 min at room temperature. The thermospray mass spectrum of cortisol 21-acetate showed minimal fragmentation with the [M + H]+ ion as the base peak. High sensitivity was achieved for acetylated cortisol during selected ion monitoring, the signal-to-noise ratio being increased by a factor of about 4, compared to underivatized cortisol. The limit of detection of cortisol 21-acetate was estimated at 0.24 pmol injected, making thermospray liquid chromatography-mass spectrometry competitive with gas chromatography-mass spectrometry for the determination of cortisol in biological fluids.

Acetylation↗
PubMed1991

Evaluation of an automated thermospray liquid chromatography-mass spectrometry system for quantitative use in bioanalytical chemistry.

An automated thermospray liquid chromatography-mass spectrometry system is described, including an autosampler and a gradient liquid chromatography system controlled from the mass spectrometer data system. The performance and reliability of the equipment during unattended operation were evaluated by repeated injections of standard solutions of some antiasthmatic drugs, using deuterium-labelled analogues as internal standards. High sensitivity and reproducibility were achieved during a 19-hour run, incorporating gradient elution and a total of 54 injections. The relative standard deviation of the peak area measurement of the internal standards was in the range of 6.5-8.2%. The corticosteroid budesonide can be routinely measured in plasma down to 0.1 nmol/l. Direct injection of a small plasma volume into the thermospray liquid chromatography-mass spectrometry system could be used to monitor drug plasma levels during a toxicity study in dogs.

Animals↗