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D Potter

Publications and source records attributed to D Potter.

At least 37 records · Page 2Linked to original sources
PubMed1996

32P-post-labelling analysis of DNA adducts formed in the upper gastrointestinal tissue of mice fed bracken extract or bracken spores.

Bracken toxicity to both domestic and laboratory animals is well established and tumours are formed when rodents are treated with either bracken extracts or bracken spores. In this study we have administered bracken spores and extract to mice in order to investigate whether such exposure leads to the formation of DNA adducts. DNA, isolated from the upper gastrointestinal tract and liver, was digested to 3'-nucleotides. Adducts were extracted with butanol, 32P-post-labelled, separated by thin layer chromatography (TLC) and visualised and quantified using storage-phosphor technology. A cluster of adducts was clearly seen in the DNA of the upper gastrointestinal tract, but not liver, 5 and 24 h after treatment with bracken extract or bracken spores. These adducts were not observed in DNA extracted from vehicle-treated animals. Whereas, after 5 h adduct levels in extract and spore-treated animals were similar, after 24 h adduct levels in the extract-treated animals had diminished by > 75%, but levels in spore-treated animals remained similar to those found after 5 h. This suggests that the DNA-reactive compounds were being released slowly from the spores, even though the spores had been sonicated before administration. Adducts were also quantified after the addition of an internal standard (deoxyinosine 3'-monophosphate) by comparing the amount of label incorporated into the adducts with that found in a known amount of the internal standard. Adduct levels using this internal standard approach were similar to those found by direct measurement of radioactivity incorporated into the adduct, indicating that the labelling of adducts was quantitative. We have tried, unsuccessfully, to synthesise ptaquiloside, the principal carcinogenic component present within bracken. However, similar patterns of adducts were observed when two other compounds, (1-(4-chlorophenyl sulphonyl)-l-cyclopropane carbonitrile and 3-cyclopropylindeno [1,2-c] pyrazol-4-(O-methyl)oxime), which both contain a cyclopropyl ring, were administered to mice. The adducts detected in bracken-treated animals may, thus, have arisen from ptaquiloside but, whether these adducts arise directly from the compounds and bracken spores/extract themselves or via an indirect mechanism, remains to be determined. As bracken-induced DNA adducts are detectable in rodent tissues by a 32P-post-labelling procedure commonly employed to investigate DNA damage in human populations, it may prove possible to apply such approaches to determine human exposure.

Animals↗
PubMed1995

Changes in the contact system during orthotopic liver transplantation with and without aprotinin.

The main cause of nonsurgical bleeding during orthotopic liver transplantation has been attributed to be hyperfibrinolysis due to high plasma levels of tissue plasminogen activator. The aim of this study was to investigate contact activation and its possible contribution to fibrinolysis during OLT with and without aprotinin. Aprotinin or placebo was given to 20 patients undergoing OLT as part of a randomized double-blind trial. Plasma samples were collected before, during, and after OLT. There were decreased preoperative levels of prekallikrein and factor XIIa (P < 0.05), with a trend for kallikrein and factor XIIa activity to increase during OLT peaking on reperfusion (P < 0.05). Kallikrein inhibition, C1 esterase inhibitor, and alpha-2-macroglobulin levels were normal before surgery, with low normal levels of antithrombin III and alpha-2-antiplasmin; these levels decreased during OLT with no specific change on reperfusion. In the aprotinin-treated group, kallikrein inhibition levels increased (P < 0.05) from preoperative mean (+/- SD) values of 101 +/- 47% to 154 +/- 42% and antiplasmin levels increased (P < 0.05) from 72 +/- 28% to 243 +/- 53% during the anhepatic phase, reflecting the effect of aprotinin. The antifibrinolytic effect of aprotinin was demonstrated by decreased levels of D-dimer on reperfusion (P < 0.05) and at the end of OLT (P < 0.001) in the aprotinin-treated group. We have shown that contact activation during OLT is minimal and that aprotinin does not alter the pattern of contact activation, but provides an antikallikrein effect.

Adult↗
PubMed1995

Cladistic analyses of combined traditional and molecular data sets reveal an algal lineage.

The chromophyte algae are a large and biologically diverse assemblage of brown seaweeds, diatoms, and other golden algae classified in 13 taxonomic classes. One subgroup (diatoms, pedinellids, pelagophytes, silicoflagellates, and certain enigmatic genera) is characterized by a highly reduced flagellar apparatus. The flagellar apparatus lacks microtubular and fibrous roots, and the flagellum basal body is attached directly to the nucleus. We hypothesize that the flagellar reduction is the result of a single evolutionary series of events. Cladistic analysis of ultrastructural and biochemical data reveals a monophyletic group that unites all taxa with a reduced flagellar apparatus, supporting our hypothesis. Phylogenetic analyses of 18S rRNA gene sequence data provide strong resolution within most of the major groups of chromophytes but only weakly resolve relationships among those groups. Some of the molecularly based most parsimonious trees, however, also unite the taxa with a reduced flagellar apparatus, although the diatoms are not included in this lineage. This grouping is further supported by a posteriori character weighting of the molecular data, suggesting that flagellar reduction occurred at least twice in parallel evolutionary series of events. To further test our hypothesis of a single evolutionary reduction in the flagellar apparatus, we combine the two data sets and subject the hybrid data matrix to parsimony analysis. The resulting trees unite the diatoms with the other reduced flagellar apparatus algae in a monophyletic group. This result supports our hypothesis of a single evolutionary reduction and indicates the existence of a previously unrecognized lineage of algae characterized by a highly reduced flagellar apparatus. Further, this study suggests that the traditional classification of the diatoms with the chrysophytes and xanthophytes in the division (= phylum) Chrysophyta, as presented in most textbooks, is unsatisfactory and that a significantly different classification should be employed.

Base Sequence↗
PubMed1995

Acute post-streptococcal glomerulonephritis in a renal allograft.

We report a 12-year-old male with acute post-streptococcal glomerulonephritis (APSGN) occurring 1 year after a cadaveric renal transplant. Although recurrent and de novo renal transplant glomerulonephritides have been well described in large series of adult and pediatric renal transplant recipients, post-infectious glomerulonephritis has been rarely reported, and APSGN has never been reported in either adult or pediatric transplant series. We speculate on the reasons for the lack of occurrence of APSGN in renal transplant recipients.

Acute Disease↗
PubMed1995

Popliteal artery injury complicating arthroscopic meniscectomy.

We describe two patients who sustained serious vascular complications following arthroscopic lateral meniscectomy. Such injuries are rarely encountered or reported in the literature and, as such, the potential catastrophic sequelae of this particular complication of arthroscopy may be underestimated. Investigation of suspected popliteal artery injuries is outlined and the need for a high index of suspicion and early referral to a vascular surgeon is stressed.

Aneurysm, False↗
PubMed1994

Fibrinolytic activity during orthotopic liver transplantation with and without aprotinin.

Hyperfibrinolysis during orthotopic liver transplantation (OLT) has been attributed to high plasma levels of tissue plasminogen activator (t-PA). This study investigated the contribution of urokinase plasminogen activator (u-PA) to hyperfibrinolysis and the effects of high-dose perioperative aprotinin (Trasylol) on fibrinolytic activation. Plasma samples were collected before, during, and after OLT in fifty five patients receiving either high dose aprotinin or placebo in a randomized double-blind trial. t-PA antigen and u-PA antigen and activity levels were increased preoperatively compared with normal controls (P < 0.05). Hyperfibrinolysis was seen during the anhepatic phase as shown by shortened euglobulin clot lysis times (ECLT) and an increase in D-dimer titers. t-PA levels peaked on reperfusion and fell at the end of the operation, and u-PA levels did not increase during OLT, but showed a decrease at the end of the operation. With aprotinin treatment, t-PA levels were lower on graft reperfusion than the placebo group (P < 0.05), but there was no difference in u-PA antigen or activity levels between groups. Fibrinolytic inhibition during OLT by aprotinin was demonstrated by prolonged ECLT (P < 0.05), reduced D-dimer levels (P < 0.05), and an increase in antiplasmin activity (P < 0.05). This study showed that the main antifibrinolytic action of aprotinin is as an antiplasmin agent with some effect on t-PA-but not u-PA-mediated fibrinolysis.

Adult↗
PubMed1994

Orthotopic liver transplantation in patients over 60 years old.

A retrospective examination was performed, including a case control study, of 40 patients aged 60 years and over who underwent liver transplantation at King's College Hospital, London, UK, between 1988 and September 1993. There was no significant difference between elderly patients and younger patients in preoperative condition, intraoperative interventions, or outcome assessed by survival, complication rate, and duration of stay on the intensive care unit. The only significant difference between age groups was the median length of hospital stay, which was 24 days for the elderly versus 20 days for younger patients. We conclude that age up to 70 years should not be a barrier to liver transplantation.

Adolescent↗
PubMed1994

Comparison of enteral feeding and total parenteral nutrition after liver transplantation.

Total parenteral nutrition is used for nutritional support in patients undergoing orthotopic liver transplantation but is associated with complications. We compared the efficacy and tolerability of early enteral feeding with total parenteral nutrition after liver transplantation. 24 patients were studied: 14 received enteral feeding and 10 total parenteral nutrition. A double-lumen enteral tube was used to deliver the feed directly into the jejunum with the second lumen of the tube being used for gastric aspiration. Enteral feeding was started post-operatively within 18 h, was well-tolerated, and of comparable efficacy to total parenteral nutrition. The median number of days for patients to start eating (4) and to achieve 70% of estimated requirements orally (5) did not differ significantly between the two groups. Mid-arm circumference, triceps skinfold thickness, and biceps skinfold thickness were, by comparison with pre-operative values, maintained on the tenth postoperative day in both groups. Early postoperative absorptive capacity, as assessed by a combined carbohydrate test, was reduced significantly in both groups but insufficiently to be of nutritional concern. Intestinal mucosal integrity, as assessed by an intestinal permeability test, was maintained throughout. We conclude that the practical aspects of enteral feeding after liver transplantation are surmountable and that enteral feeding is as effective at maintaining nutritional status as total parenteral nutrition, and has potential benefits in terms of reduced complications and costs.

3-O-Methylglucose↗
PubMed1994

Bone marrow necrosis in two patients with acute promyelocytic leukemia during treatment with all-trans retinoic acid.

All-trans retinoic acid has been used for the treatment of acute promyelocytic leukemia (APL) with encouraging results. However, it has recently been associated with a number of potentially serious complications including the retinoic acid syndrome. We describe two patients with APL who were begun on all-trans retinoic acid therapy (45 mg/m2), but who developed leukocytosis which was treated with hydroxyurea. Both patients demonstrated clinical and laboratory findings of disseminated intravascular coagulation, massive cell lysis manifested by marked increases in serum lactic dehydrogenase, and rapid clinical deterioration. Both patients developed bone marrow necrosis within viable, noninfarcted bone trabeculae. We postulate that the development of bone marrow necrosis in these two patients was not a chance occurrence. Rather, the specific combination of cytotoxic and differentiating agents used in these patients (hydroxyurea with all-trans retinoic acid) caused massive cell lysis and death. The absence of bone marrow necrosis in the setting of induction therapy for APL both with and without all-trans retinoic acid therapy suggests that the addition of hydroxyurea was critical to the development of marrow necrosis. We, therefore, recommend caution in the use of hydroxyurea and all-trans retinoic acid in the treatment of APL.

Adult↗
PubMed1994

Molecular dosimetry of DNA adducts in rainbow trout (Oncorhynchus mykiss) exposed to benzo(a)pyrene by different routes.

Farm raised rainbow trout (Oncorhynchus mykiss) were exposed by various routes to benzo(a)pyrene (BP) as a representative carcinogenic polycyclic aromatic hydrocarbon (PAH). Following exposure of fish to the chemical by intraperitoneal (i.p.) injection, 32P-postlabelling studies indicated that non-feral trout were relatively resistant to the formation of BP-DNA adducts in liver. No adducts were detected in fish exposed to single doses (20 mg/kg) of BP. Multiple exposures (e.g. 2 x 25 mg/kg) were necessary in order for adducts to be detected, indicating that induction of the metabolising enzymes required for the bioactivation of BP is necessary. These studies provided reference information on DNA adducts for comparison with data from subsequent experiments at environmentally realistic low level exposures. Two types of low level aquatic exposure were carried out. The first procedure exposed fish for 30 days to a nominally constant low level (1.2 and 0.4 micrograms/l) of a homogeneous dispersion of BP in water, to simulate low level aquatic environmental exposures. Following 32P-postlabelling analysis of the liver DNA of exposed fish, BP-DNA adducts were not detected. In the second procedure, fish were exposed to a constant low level of BP (ca. 0.5 micrograms/l) for 15 days then to a pulse (60 micrograms/l) which was allowed to naturally decline (to ca. 2 micrograms/l) during a further 15 days. Following this exposure, significant levels of BP-DNA adducts were detected in livers of trout. The effect of dietary exposures was investigated by feeding trout a diet containing either 58 micrograms or 288 micrograms BP per day for 6 days, equivalent to total doses of 43 mg/kg and 216 mg/kg.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1994

Patterns of injuries to children on public playgrounds.

The incidence and pattern of injuries to children in public playgrounds presenting to the accident and emergency department were reviewed over two six month summer periods in Cardiff. A total of 178 children (mean age 7.5 years) attended with a playground injury representing 1.1% of all the children attending. One hundred and five children fell from equipment, of which the commonest was the climbing frame; 125 children had playground surface related injuries, 86 on bark and 30 on concrete. The pattern of injuries on the playground surfaces was different: fractures and sprains were more common on bark surfaces and lacerations and abrasions on concrete surfaces. Comparison of total injury rates showed there were fewer injuries on modernised playgrounds than expected but these differences were not significant. Modernised playgrounds are more popular, have new exciting equipment, and offer good play opportunities for children. However, the high fracture rate on modernised bark playgrounds is concerning and requires further research.

Accidents↗
PubMed1993

In vivo fate of hemopexin and heme-hemopexin complexes in the rat.

The disposition in the rat of the plasma heme-binding protein hemopexin (Hx), as the native apoprotein and as its heme complex (HHx), has been studied using the residualizing protein label dilactitol-125I-tyramine (*I-DLT). The aim of this work was to identify the tissue sites of Hx uptake and catabolism, independent of heme binding, and to evaluate how heme loading affects Hx catabolism at these sites. *I-DLT-Hx had a circulating half-life of approximately 1.2 days and was recovered in degraded form in comparable amounts in visceral (liver, kidney, spleen) and peripheral (skin, muscle) tissues, indicating a generalized diffuse catabolism of the protein throughout the body. The plasma half-life of *I-DLT-Hx injected as a preformed heme-Hx complex was the same as that of the apoprotein; however, injection of the complex resulted in about a twofold increase in hepatic degradation of Hx. The lack of an effect of heme on overall catabolism of the preformed HHx complex was consistent with the approximately 1-h half-life of heme, injected as 14C-heme-Hx, in the circulation; however, as much as 20-fold more 14C-heme than Hx protein was recovered in liver from 14C-heme-Hx. The absolute amount of *I-DLT-Hx degraded in liver was significantly increased when heme was injected in excess of the heme binding capacity of circulating Hx, while 131I-DLT-albumin catabolism in liver was unaffected. Thus, depending on the physiological conditions studied, the data are consistent with a model in which, following hepatic uptake of heme from HHx, varying proportions of the protein are either returned to the circulation or degraded in the liver.

Animals↗
PubMed1993

A multicenter, randomized, double-blind, placebo-controlled, dose-titration study of oral pilocarpine for treatment of radiation-induced xerostomia in head and neck cancer patients.

PURPOSE: To determine the efficacy and safety of pilocarpine hydrochloride for symptomatic relief of postradiation xerostomia symptoms and for saliva production in patients with head and neck cancer. PATIENTS AND METHODS: One hundred sixty-two head and neck cancer patients who had received at least 40 Gy of radiation (117 patients had received > 60 Gy) with clinically significant xerostomia were enrolled onto a randomized, double-blind, placebo-controlled, multi-center clinical investigation. Patients received 2.5-mg tablets for the first 4 weeks, 5.0-mg tablets for the second 4 weeks, and 10.0-mg tablets for the last 4 weeks of the 12-week study. Patients were allowed to titrate pilocarpine or placebo for improvement in symptoms or to reduce side effects. Patients were evaluated for symptomatic relief by questionnaires and visual analog scales (VAS), and for saliva production by sialometry. RESULTS: Pilocarpine produced a significant improvement (P = .035) in overall global assessments compared with placebo. There was a statistically significant (P = .020) decreased use of oral comfort agents such as artificial saliva, hard candy, and water. Values for symptomatic improvement in dryness approached significance (P = .057). There were statistically significant postdose improvements in whole and parotid salivary flow in pilocarpine treatment groups versus placebo. All pilocarpine dosages tested were judged to be safe. Adverse experiences were primarily sweating, rhinitis, headache, nausea, and urinary frequency, with the most common side effect being mild to moderate sweating. There were no serious drug-related adverse experiences in any of the pilocarpine treatment groups. CONCLUSION: It is concluded that pilocarpine produces clinically significant benefits for the symptomatic treatment of postradiation xerostomia. Best results were obtained with continuous treatment for 8 to 12 weeks with doses greater than 2.5 mg three times per day.

Administration, Oral↗