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Biomedical subjects

R Coleman

Publications and source records attributed to R Coleman.

At least 109 records · Page 6Linked to original sources
PubMed1999

Assessment of bone response to systemic therapy in an EORTC trial: preliminary experience with the use of collagen cross-link excretion. European Organization for Research and Treatment of Cancer.

This study was designed to evaluate new bone resorption and tumour markers as possible alternatives to serial plain radiographs for the assessment of response to treatment. Thirty-seven patients with newly diagnosed bone metastases from breast cancer, randomized to receive oral pamidronate or placebo tablets in addition to anticancer treatment within the context of a multicentre EORTC trial, who were both assessable for radiographic response in bone and had serum and urine samples collected for more than 1 month were studied. The markers of bone metabolism measured included urinary calcium (uCa), hydroxyproline (hyp), the N-telopeptide cross-links of type I collagen (NTx) and total alkaline phosphatase. The tumour markers measured were CA15-3 and cancer-associated serum antigen (CASA). Before treatment, levels of Ntx, uCa and Hyp were elevated in 41%, 24% and 28% respectively, and CA15-3 and CASA increased in 69% and 50%. For assessment of response and identification of progression, Ntx was the most useful bone marker. All markers behaved similarly in no change (NC) and partial response (PR) patients. There was a significant difference (P < or = 0.05) in Ntx levels (compared to baseline) at 1 and 4 months and in CA15-3/CASA at 4 months between patients with PR or NC and those with progressive disease (PD), and at 4 months between those with time to progression (TP) > 7 and those with TP < or = 7 months. The diagnostic efficiency (DE) for prediction of PD following a > 50% increase in Ntx or CA15-3 was 78% and 62% respectively. An algorithm to predict response to therapy has been developed for future prospective evaluation.

Adult↗
PubMed1999

Carcase characteristics of emus (Dromaius novaehollandiae).

1. Six emus (Dromaius novaehollandiae) were slaughtered at 13 months of age in order to determine carcase, by-product and muscle yields. 2. Emus had a lower percentage of hot carcase weight (52%) and total fat (28%) to body weight but a higher lean meat to carcase weight (69%) than ostriches or rheas. 3. The amount of trimming of connective tissue from muscles of the lower leg (Gastrocnemius, Fibularis longus) has an influence (P<0.05) on the yields from these muscles.

Adipose Tissue↗
PubMed1999

Field investigations of an outbreak of Ebola hemorrhagic fever, Kikwit, Democratic Republic of the Congo, 1995: arthropod studies.

During the final weeks of a 6-month epidemic of Ebola hemorrhagic fever in Kikwit, Democratic Republic of the Congo, an extensive collection of arthropods was made in an attempt to learn more of the natural history of the disease. A reconstruction of the activities of the likely primary case, a 42-year-old man who lived in the city, indicated that he probably acquired his infection in a partly forested area 15 km from his home. Collections were made throughout this area, along the route he followed from the city, and at various sites in the city itself. No Ebola virus was isolated, but a description of the collections and the ecotopes involved is given for comparison with future studies of other outbreaks.

Adult↗
PubMed1999

ANIT-induced disruption of biliary function in rat hepatocyte couplets.

alpha-Naphthylisothiocyanate (ANIT) induces intrahepatic cholestasis in rats, involving damage to biliary epithelial cells; our study aims to investigate whether disruption of biliary function in hepatocytes can contribute to early stages of ANIT-induced intrahepatic cholestasis. Isolated rat hepatocyte couplets were used to investigate biliary function in vitro by canalicular vacuolar accumulation (cVA) of a fluorescent bile acid analogue, cholyl-lysyl-fluorescein (CLF), within the canalicular vacuole between the two cells. After a 2-h exposure to ANIT, there was a concentration-dependent inhibition of cVA (cVA-IC50; 25 microM), but no cytotoxicity (LDH leakage or [ATP] decline) within this ANIT concentration range. There was no loss of cellular [GSH] at low ANIT concentrations, but, at 50 microM ANIT, a small but significant loss of [GSH] had occurred. Diethylmaleate (DEM) partially depleted cellular [GSH], but addition of 10 microM ANIT had no further effect on GSH depletion. Reduction in cVA was seen in DEM-treated cells; addition of ANIT to these cells reduced cVA further, but the magnitude of this further reduction was no greater than that caused by ANIT alone, indicating that glutathione depletion does not enhance the effect of ANIT. F-actin distribution (by phalloidin-FITC staining) showed an increased frequency of morphological change in the canalicular vacuoles but only a small, non-significant (0.05 < p < 0.1) increase in proportion of the F-actin in the region of the pericanalicular web. The results are in accord with a disruption of hepatocyte canalicular secretion within two h in vitro, at low, non-cytotoxic concentrations of ANIT, and the possible involvement of a thiocabamoyl-GSH conjugate of ANIT (GS-ANIT) in this effect.

1-Naphthylisothiocyanate↗
PubMed1999

Phase II study of gemcitabine as first-line chemotherapy in patients with advanced or metastatic breast cancer.

In this phase II study, the efficacy and tolerability of gemcitabine were studied in 42 patients with locally advanced or metastatic breast cancer who had received up to one prior chemotherapy regimen in an adjuvant setting. Ten patients had received adjuvant chemotherapy. Twenty-eight patients (67%) had visceral disease spread at entry. Gemcitabine (1000 mg/m2) was administered weekly on days 1, 8 and 15 of a 28-day cycle. The mean number of completed cycles was 3.9 and the mean dose delivered was 942.2 mg/m2. Ninety-seven percent of injections were administered as assigned. No complete responses were observed, but there were six partial responses and 24 patients with stable disease lasting 2-9 months. The overall response rate was 14.3% (95% CI 5.4-28.5%). The median survival for all patients was 15.2 months. Maximum WHO grade 3 and 4 toxicities were observed in five patients for nausea and vomiting, one patient for diarrhea, one patient for pain, seven patients for alanine transaminase, and eight patients for segmented neutrophils. There were no grade 3 and 4 toxicities for alopecia. These data confirm modest single-agent gemcitabine activity in advanced or metastatic breast cancer. Gemcitabine's favorable toxicity profile makes it an ideal candidate for combination chemotherapy.

Adult↗
PubMed1999

Docetaxel and cisplatin in combination as first-line chemotherapy for advanced epithelial ovarian cancer. Scottish Gynaecological Cancer Trials Group.

PURPOSE: A prospective, nonrandomized, multicenter, open feasibility study of cisplatin and docetaxel as first-line chemotherapy in International Federation of Gynecology and Obstetrics (FIGO) stage IC-IV epithelial ovarian cancer was conducted. The primary end point was the incidence of severe fluid retention that necessitated treatment withdrawal. PATIENTS AND METHODS: Cisplatin and docetaxel were administered every 3 weeks for six planned cycles, with a 5-day prophylactic dexamethasone regimen (8 mg two times per day). One hundred patients (median age, 53 years; range, 24 to 71 years) received a total of 512 cycles of chemotherapy in two cohorts: cohort 1, 49 patients, 258 cycles (cisplatin 75 mg/m(2) and docetaxel 75 mg/m(2)); cohort 2, 51 patients, 254 cycles (cisplatin 75 mg/m(2) and docetaxel 85 mg/m(2)). RESULTS: No patients were taken off study because of fluid retention. Sixty-six patients completed six cycles of protocol therapy; 16 stopped early because of toxicity (neurotoxicity in six patients, nephrotoxicity in three, neutropenia in two, and hypersensitivity, diarrhea and vomiting, skin rash, clinical deterioration, and patient's wishes in one patient each). Grade 3/4 neutropenia was observed in more than 75% of patients and seemed to be cumulative. Patients in cohort 2 had significantly more severe neutropenia and lethargy than those in cohort 1. In addition, there were five treatment-related deaths in cohort 2 (three neutropenia and two upper gastrointestinal hemorrhage). Neurotoxicity (mainly sensory, > grade 1) was observed in 23 patients. The overall clinical response rate was 69% (complete response, 38%; partial response, 31%); CA-125 response rate was 73%. Median progression-free survival for the group was 12 months. CONCLUSION: Cisplatin and docetaxel can be administered at doses of 75 mg/m(2) and 75 mg/m(2), respectively, every 3 weeks, and the utility of this regimen is not limited by fluid retention. However, 33 of 100 patients were unable to complete the planned six cycles, which may explain, in part, the poor overall progression-free survival. Increasing the docetaxel dose to 85 mg/m(2) adds unacceptable hematologic toxicity and potential risks to the patient.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

Muscle recovery after immobilisation by external fixation.

We immobilised the right hindlimbs of six-month-old female Wistar rats for four weeks using a biplanar external fixation bridging the knee. The untreated left limbs served as a control group. An additional group of rats was allowed to recover for four weeks after removal of the frame. Immobilisation caused reduction in the wet weights of approximately 50% in the gastrocnemius, quadriceps, soleus and plantaris muscles; this was not restored completely after remobilisation. There was an increase in the activity of acid phosphatase of approximately 85% in the gastrocnemius and quadriceps muscles whereas that of creatine phosphokinase was reduced by about 40%. These values returned to nearly normal after remobilisation. Histological and ultrastructural examination showed a marked myopathy of the gastrocnemius muscle after immobilisation although the morphology was largely restored after remobilisation. We conclude that after four weeks of remobilisation, hind-limb muscles do not return to preimmobilisation weights, although biochemical activities and ultrastructural appearance are largely restored.

Acid Phosphatase↗
PubMed1999

Integrating a modern knowledge-based system architecture with a legacy VA database: the ATHENA and EON projects at Stanford.

We present a methodology and database mediator tool for integrating modern knowledge-based systems, such as the Stanford EON architecture for automated guideline-based decision-support, with legacy databases, such as the Veterans Health Information Systems & Technology Architecture (VISTA) systems, which are used nation-wide. Specifically, we discuss designs for database integration in ATHENA, a system for hypertension care based on EON, at the VA Palo Alto Health Care System. We describe a new database mediator that affords the EON system both physical and logical data independence from the legacy VA database. We found that to achieve our design goals, the mediator requires two separate mapping levels and must itself involve a knowledge-based component.

Artificial Intelligence↗
PubMed1998

The Medical Journal of Australia Internet peer-review study.

BACKGROUND: Peer review of medical papers is a confidential consultancy between the reviewer and the journal editor, and has been criticised for its potential bias and inadequacy. We explored the potential of the internet for open peer review to see whether this approach improved the quality and outcome of peer review. METHODS: Research and review articles that had been accepted for publication in The Medical Journal of Australia (MJA) were published together with the reviewers' reports on the worldwide web, with the consent of authors and referees. Selected readers' e-mailed comments were electronically published as additional commentary; authors could reply or revise their paper in response to readers' comments. Articles were edited and published in print after this open review. FINDINGS: 60 (81%) of 74 authors agreed to take part in the study, together with 150 (92%) of 162 reviewers. There was no significant difference in the performance of commissioned reviewers before and during the study. Four articles were not included because of insufficient time before print publication. Of the remaining 56 papers, 28 received 52 comments from 42 readers (2% of readers submitted comments). Most readers' comments were short and specific, and seven articles were changed by the authors in response. INTERPRETATION: Open peer review is acceptable to most authors and reviewers. Postpublication review by readers on the internet is no substitute for commissioned prepublication review, but can provide editors with valuable input from individuals who would not otherwise be consulted. Readers also gain insight into the processes of peer review and publication.

Attitude↗
PubMed1998

Involvement of nitric oxide system in experimental muscle crush injury.

Muscle crush injury is often complicated by hemodynamic shock, electrolyte disorders, and myoglobinuric renal failure. In this study, we examined the involvement of the nitric oxide (NO) system in the development of muscle damage in an experimental model of crush injury induced by exertion of standardized mechanical pressure on tibialis muscle of rat. The intact limb served as a control. Four days after injury, the crushed muscle was characterized by extreme capillary vasodilatation as demonstrated by histological morphometric analysis. These changes were accompanied by muscle hyperperfusion as evaluated by measurements of femoral blood flow (ultrasonic flowmetry) and capillary blood flow (laser-doppler flowmetry). Treatment with Nomega-nitro-L-arginine methyl ester, a NO synthase (NOS) inhibitor, largely decreased the hyperperfusion. Furthermore, the expression of the different NOS isoforms, assessed by reverse transcription-PCR and immunoreactive levels, determined by Western blot, revealed a remarkable induction of the inducible NOS in the crushed limb. Similarly, endothelial NOS mRNA increased gradually after the induction of muscle damage. In contrast, the major muscular NOS, i.e., neuronal isoform remained unchanged. In line with the alterations in the mRNA levels, Western blot analysis revealed parallel changes in the immunoreactive levels of the various NOS. These findings indicate that muscle crush is associated with activation of the NO system mainly due to enhancement of iNOS. This may contribute to NO-dependent extreme vasodilatation in the injured muscle and aggravate the hypovolemic shock after crush injury.

Animals↗
PubMed1998

Fas (CD95/Apo-1)-mediated damage to ventricular myocytes induced by cytotoxic T lymphocytes from perforin-deficient mice: a major role for inositol 1,4,5-trisphosphate.

Cytotoxic T lymphocytes (CTLs) that infiltrate the heart are important immune effectors implicated in heart transplant rejection, myocarditis, and other cardiomyopathies. To investigate the mechanism(s) underlying CTL damage to the myocardium through activation of the Fas receptor (Fas/CD95/Apo-1) by the Fas ligand, we explored the interaction between peritoneal exudate CTLs (PELs), derived from perforin gene-knockout (P-/-) mice, and murine ventricular myocytes. Fas expression on isolated ventricular myocytes was demonstrated immunohistochemically. Action potentials, [Ca2+]i transients, and contractions of myocytes conjugated to P-/- PELs or treated with the apoptosis-inducing anti-Fas monoclonal antibody Jo2 were recorded. Action potential characteristics of nonconjugated myocytes and myocytes conjugated with P-/- PELs were, respectively, as follows: Vm, -73.2+/-1.5 and -53.6+/-6.4 mV (mean+/-SEM); action potential amplitude, 117.9+/-3.9 and 74.3+/-21.2 mV; and action potential duration at 80% repolarization, 17+/-6 and 42+/-13 milliseconds (all P<.05). P-/- PELs also induced early and delayed afterdepolarizations as well as arrhythmogenic activity. Diastolic [Ca2+]i increased during the cytocidal interaction with P-/- PELs, from a fluorescence ratio of 0.82+/-0.05 (n=7) to 1.98+/-0.09 (n=13) (P<.05). All of the effects caused by P-/- PELs were reproduced by incubating the myocytes with Jo2. Heparin (50 microg/mL), an antagonist of inositol trisphosphate (IP3)-operated sarcoplasmic reticulum Ca2+ channels, or U-73122 (2 micromol/L), a phospholipase C inhibitor, but not the inactive agonist U-73343, prevented Fas-mediated myocyte dysfunction. Additionally, intracellular application (through the patch pipette) of the active IP3 analogue, inositol 1,4,5-trisphosphate, but not the inactive analogue, inositol 1,3,4-trisphosphate, caused electrophysiological changes resembling those resulting from P-/- PELs and Jo2, suggesting that CTL-induced Fas-based myocyte dysfunction is mediated by IP3. We conclude that a Fas-based perforin-independent mechanism of CTL action can account for the immunopathology seen in the allotransplanted heart, myocarditis, and dilated cardiomyopathy.

Action Potentials↗
PubMed1998

Vasopressin-induced disruption of actin cytoskeletal organization and canalicular function in isolated rat hepatocyte couplets: possible involvement of protein kinase C.

The effect of vasopressin (VP) on canalicular function and hepatocellular morphology, with particular regard to actin cytoskeletal organization and the concomitant plasma membrane bleb formation, was studied in isolated rat hepatocyte couplets. VP induced the concentration-dependent formation of multiple plasma membrane blebs as well as simultaneous impairment in both canalicular vacuolar accumulation (cVA) and retention (cVR) of the fluorescent bile acid, cholyl-lysyl-fluorescein (CLF), which evaluate couplet secretory function and tight-junction integrity, respectively. These effects were mimicked by the protein kinase C (PKC) activator, phorbol dibutyrate (PDB), but not by the protein kinase A (PKA) activator, dibutyryl-cAMP. VP-induced bleb formation and canalicular dysfunction were fully prevented by the protein kinase inhibitor, H-7, but not by the PKA inhibitor, KT5720, further suggesting a specific role of PKC. VP-induced alterations were also prevented by pretreatment with the Ca2+-buffering agent, BAPTA/AM, but not with the calmodulin-dependent protein kinase II antagonist, calmidazolium. Neither the Ca2+-activated neutral protease inhibitor, leupeptin, nor the antioxidants, alpha-tocopherol or deferoxamine, were able to prevent either VP-induced plasma membrane blebbing or canalicular dysfunction. The Ca2+-ionophore, A23187, mimicked the VP-induced alterations, but its harmful effects were completely prevented by H-7. Bleb formation induced by VP and PDB was accompanied by an extensive redistribution of filamentous actin from the pericanalicular area to the cell body, and this effect was fully prevented by H-7. These results suggest that VP-induced canalicular and cytoskeletal dysfunction is mediated by PKC and that classical (Ca2+-dependent) PKC appear to be involved because intracellular Ca2+ is required for VP to induce its harmful effects.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1998

Hepatobiliary effects of tertiary-butylhydroperoxide (tBOOH) in isolated rat hepatocyte couplets.

The organic hydroperoxide, tertiary-butylhydroperoxide (tBOOH), causes oxidative damage in a number of cell types. It is used here in an isolated rat hepatocyte couplet preparation to study adverse hepatobiliary effects of peroxidative damage in vitro. At subcytotoxic concentrations (as determined by lactate dehydrogenase release and maintenance of cytoplasmic ATP concentrations) tBOOH caused decreased accumulation of a fluorescent bile acid analogue, cholyl-lysyl-fluorescein (CLF), in the canalicular vacuole of couplets (a hepatobiliary effect; cholestasis). This was dose dependent in the range 100-200 microM. At the same concentrations it brought about release of preaccumulated CLF, suggesting that its effect was more likely to be on sealing properties of the vacuole than processes of uptake, transcytosis, and secretion. Pretreatment of tBOOH-treated couplets with the antioxidants deferoxamine mesylate (iron chelator) and dimethyl sulfoxide (free radical scavenger) resulted in the prevention of both canalicular vacuolar accumulation (cVA, which assesses canalicular function) and canalicular vacuolar retention (cVR, which assesses the retaining ability of couplets) depression at 100 microM tBOOH but not at higher concentrations. This indicates that the cholestatic effect of tBOOH has a preventable and nonpreventable phase and that free radicals are involved in these processes. By selectively generating the two types of tBOOH radical, peroxyl (tBOO.) and alkoxyl (tBO.), using suitable catalysts, we were able to determine that the peroxyl radical was most probably involved in tBOOH-induced cholestasis. This was further supported by experiments employing specific peroxyl and alkoxyl radical scavengers; only the peroxyl scavenger reduced the effect of tBOOH upon canalicular function under the conditions studied.

Adenosine Triphosphate↗
PubMed1998

Novel and recurrent tyrosine aminotransferase gene mutations in tyrosinemia type II.

Tyrosinemia type II (Richner-Hanhart syndrome, RHS) is a disorder of autosomal recessive inheritance characterized by keratitis, palmoplantar hyperkeratosis, mental retardation, and elevated blood tyrosine levels. The disease results from deficiency in hepatic tyrosine aminotransferase (TAT). We have previously described one deletion and six different point mutations in four RHS patients. We have now analyzed the TAT genes in a further seven unrelated RHS families from Italy, France, the United Kingdom, and the United States. We have established PCR conditions for the amplification of all twelve TAT exons and have screened the products for mutations by direct sequence analysis or by first performing single-strand conformation polymorphism analysis. We have thus identified the presumably pathological mutations in eight RHS alleles, including two nonsense mutations (R57X, E411X) and four amino acid substitutions (R119W, L201R, R433Q, R433W). Only the R57X mutation, which was found in one Scottish and two Italian families, has been previously reported in another Italian family. Haplotype analysis indicates that this mutation, which involves a CpG dinucleotide hot spot, has a common origin in the three Italian families but arose independently in the Scottish family. Two polymorphisms have also been detected, viz., a protein polymorphism, P15S, and a silent substitution S103S (TCG-->TCA). Expression of R433Q and R433W demonstrate reduced activity of the mutant proteins. In all, twelve different TAT gene mutations have now been identified in tyrosinemia type II.

Adult↗
PubMed1998

Association of atopic dermatitis to the beta subunit of the high affinity immunoglobulin E receptor.

IgE dysregulation is a major pathogenic feature of atopic dermatitis and other IgE-mediated allergic diseases such as asthma and rhinitis. Allergen complexed to IgE binds to the high affinity receptor for IgE (Fc epsilon RI) on the surface of epidermal Langerhans cells, mast cells and basophils, triggering the release of inflammatory mediators. The beta subunit of Fc epsilon RI has been localized to human chromosome 11q12-13, and variants within this gene have been shown to associate with asthma and measures of atopy. We have tested several polymorphisms within Fc epsilon RI-beta for association to atopic dermatitis in a panel of 60 families (panel A), recruited through a proband with atopic dermatitis. The findings were tested in a second panel of families (panel B). Significant sharing of maternal alleles was seen for atopic dermatitis and allele 2 of RsaI intron 2 (RsaIvin2*2) (P = 0.0022) and allele 1 of RsaI exon 7 (RsaIvex7*1) (P = 0.0036) Fc epsilon RI-beta gene polymorphisms. These findings were replicated in Panel B, confirming the association of Fc epsilon RI-beta RsaI polymorphisms with atopic dermatitis. The combined significance of the association of atopic dermatitis to RsaI polymorphisms was P = 0.0002 (RsaIvin2*2) and P = 0.00034 (RsaIvex7*1). The polymorphisms also showed association with asthma: P = 0.0068 (RsaIvin2*2) and P = 0.018 (RsaIvex7*1). Polymorphisms within the Fc epsilon RI-beta gene are strongly associated with atopic dermatitis.

Adolescent↗