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Biomedical subjects

D J Roberts

Publications and source records attributed to D J Roberts.

At least 73 records · Page 4Linked to original sources
PubMed1997

Reducing pain after inguinal hernia repair in children: caudal anesthesia versus ketorolac tromethamine.

BACKGROUND: The optimal method to achieve analgesia after inguinal hernia repair in children is unknown. This study compared the analgesic efficacy, adverse events, and the costs associated with supplementation of local anesthesia (infiltration of the wound) with either intravenous ketorolac or caudal analgesia in children having inguinal hernia repair. METHODS: With parental consent and institutional review board approval, children aged 2-6 yr having elective, outpatient inguinal hernia repair were studied in this randomized, single-blinded investigation. Anesthesia was induced by inhalation with nitrous oxide and halothane or intravenously with propofol. Anesthesia was maintained with nitrous oxide and halothane. Patients were randomly assigned to receive caudal analgesia (1 ml/kg 0.20% bupivacaine with 1/200,000 epinephrine) or intravenous ketorolac (1 mg/kg) immediately after induction of anesthesia. Both groups received field blocks with 0.25% bupivacaine administered by the surgeon under direct vision during operation. Patients were assessed for 24 h. In-hospital pain was assessed using a behavior-based pain score. Parents assessed pain with a visual linear analog pain scale with anchors of 0 (no pain) and 100 (worst pain imaginable). RESULTS: The authors studied 164 children, with 84 patients in the ketorolac group. The groups had similar demographic data. In-hospital analgesic requirements and pain scores were almost identical in both groups. Pain at home was significantly less in the ketorolac group, with visual linear analog pain scale scores of 10 (0-80) compared with 20 (0-80) (median [range]) for ketorolac versus caudal (P = 0.002 by the Mann-Whitney U test). The ketorolac group also had a lower incidence of vomiting, ambulated more rapidly, and micturated earlier (P < 0.05). CONCLUSION: The use of intravenous ketorolac to supplement local anesthesia infiltrated by the surgeon during pediatric inguinal hernia repair is superior to supplementation with caudal analgesia.

Anesthesia, Caudal↗
PubMed1997

Failure to block adhesion of Plasmodium falciparum-infected erythrocytes to ICAM-1 with soluble ICAM-1.

The adhesion of Plasmodium falciparum-infected erythrocytes is thought to play a central role in the pathogenesis of severe malaria. ICAM-1 has been identified as one of the host receptors for parasitized erythrocytes and has been implicated as being involved in progression to cerebral malaria. Thus, intervention strategies based on the reversal of this interaction could potentially be used to reduce morbidity and mortality. We have investigated the inhibition of the interaction between ICAM-1 and infected erythrocytes by using recombinant soluble ICAM-1 as competitor and find that we are unable to reduce adhesion to ICAM-1 in vitro.

Animals↗
PubMed1997

Regulation of [Ca++]i in human neuroblastoma (SH-SY5Y) cells expressing recombinant rat angiotensin1A receptors by angiotensin II and carbachol.

The ability of angiotensin II (AII) to regulate [Ca++]i in human neuroblastoma (SH-SY5Y) cells stably expressing recombinant rat AT1A receptors was investigated using microfluorimetric methods, and compared to responses obtained by stimulation of native muscarinic receptors. Applications of AII or carbachol produced biphasic rises of [Ca++]i, but in Ca++-free solutions (containing 1 mM ethylene glycol-bis (beta-aminoethyl ether)N,N,N,'N'-tetraacetic acid), both agonists produced only transient monophasic rises of [Ca++]i, and second applications were without effect. Application of Ca++(o) (2.5 mM) to cells after exposure to either agonist produced a Ni2+-sensitive rise of [Ca++]i in the absence of agonist ("capacitative Ca++ influx"). After removal of Ca++(o), both AII and carbachol elicited a second rise of [Ca++]i. Thapsigargin (1 microM) prevented these second rises of [Ca++]i. During capacitative Ca++ influx, application of AII failed to produce a further rise of [Ca++]i. In contrast, carbachol produced a further rise of [Ca++]i, attributable to activation of both nicotinic and muscarinic receptors, because it was reduced (but not abolished) by mecamylamine (1 microM) and was observed when muscarine was used as the agonist. Thus, activation of recombinant AT1A and muscarinic receptors in SH-SY5Y cells leads to mobilization of Ca++ from a common intracellular pool, and stimulates capacitative Ca++ influx. Muscarinic (but not AII) receptor occupancy is capable of stimulating an additional Ca++ influx pathway.

Angiotensin II↗
PubMed1996

Eradication of high-grade dysplasia in columnar-lined (Barrett's) oesophagus by photodynamic therapy with endogenously generated protoporphyrin IX.

BACKGROUND: High-grade dysplasia in columnar-lined (Barrett's) oesophagus presents a difficult therapeutic dilemma. Choices for management are endoscopic surveillance to detect a cancer or oesophagectomy. One carries the risk of missing invasive cancer, the other carries worrying morbidity and mortality. We have used endoscopic photodynamic therapy to eradicate high-grade dysplasia. METHODS: After the oral administration of 5-aminolaevulinic acid, the accumulation of the endogenously generated photosensitiser protoporphyrin IX was measured with quantitative fluorescence microscopy. Five patients with histologically confirmed high-grade dysplasia were treated with endoscopic photodynamic therapy with 630 nm laser light to activate the photosensitiser. FINDINGS: Protoporphyrin IX accumulated in the dysplastic epithelium rather than the adjacent stroma. Selective necrosis of the dysplastic epithelium in columnar-lined oesophagus occurred after light activation. High-grade dysplasia was eradicated in all patients and squamous regeneration occurred after acid suppression with a protonpump inhibitor. There were no complications or recurrence of dysplasia after 26-44 months' endoscopic and histological follow-up. In two cases we saw non-dysplastic Barrett's epithelium underneath regenerative squamous mucosa. INTERPRETATION: High-grade dysplasia in columnar-lined oesophagus can be eradicated by endoscopic photodynamic therapy with endogenously generated PpIX. Remaining non-dysplastic Barrett's epithelium will require surveillance, but overall the technique has interrupted or delayed the worsening of the dysplasia through to carcinoma. This technique may prevent the need for surgical excision in these patients.

Aged↗
PubMed1996

Variant antigens and endothelial receptor adhesion in Plasmodium falciparum.

Parasite-derived proteins expressed on the surface of erythrocytes infected with Plasmodium falciparum are important virulence factors, since they mediate binding of infected cells to diverse receptors on vascular endothelium and are targets of a protective immune response. They are difficult to study because they undergo rapid clonal antigenic variation in vitro, which precludes the derivation of phenotypically homogeneous cultures. Here we have utilized sequence-specific proteases to dissect the role of defined antigenic variants in binding to particular receptors. By selection of protease-resistant subpopulations of parasites on defined receptors we (i) confirm the high rate of antigenic variation in vitro; (ii) demonstrate that a single infected erythrocyte can bind to intercellular adhesion molecule 1, CD36, and thrombospondin; (iii) show that binding to intercellular adhesion molecule 1 and CD36 are functions of the variant antigen; and (iv) suggest that binding to thrombospondin may be mediated by other components of the infected erythrocyte surface.

Animals↗
PubMed1996

Dexamethasone decreases vomiting by children after tonsillectomy.

We evaluated the effect of dexamethasone on vomiting after elective tonsillectomy in 133 healthy children aged 2-12 yr in a randomized, stratified, blocked, double-blind, placebo-controlled study. General anesthesia was induced by inhalation of N2O and halothane or intravenously (IV) with propofol. Anesthesia was maintained with N2O and halothane. Dexamethasone 150 micrograms/kg up to a maximum dose of 8 mg, or placebo, was administered IV before surgery. All patients received 1.5 mg/kg codeine intramuscularly (IM) intraoperatively. Perioperative IV fluids, management of emesis, postoperative pain and hospital discharge criteria were all standardized. The groups were similar with respect to number, age, weight, length of surgery, and estimated intraoperative blood loss. Dexamethasone reduced the overall incidence of vomiting from 72% (placebo) to 40% (P < 0.001). Vomiting, both in-hospital and postdischarge, was decreased by the prophylactic administration of dexamethasone. Each episode of in-hospital vomiting prolonged discharge by 13 +/- 2 min, mean +/- SD (P < 0.001). In conclusion, dexamethasone markedly decreased vomiting by healthy children after elective tonsillectomy in an ambulatory hospital setting.

Ambulatory Surgical Procedures↗
PubMed1996

The role of ketoconazole in the QTc interval prolonging effects of H1-antihistamines in a guinea-pig model of arrhythmogenicity.

We have carried out experiments to re-evaluate the influence of ketoconazole (400 mg kg-1,p.o.) on the effects of ebastine, terfenadine and loratadine on the QTc interval in conscious guinea-pigs. Following a previously described protocol of oral drug administration, but using telemetric recording of the ECG, we have found that the prolongation of the QTc interval attributed to ebastine and terfenadine is in fact entirely due to ketoconazole, and that neither terfenadine, ebastine nor loratadine produce any additional effects on subsequent administration.

Animals↗
PubMed1996

A preclinical overview of ebastine. Studies on the pharmacological properties of a novel histamine H1 receptor antagonist.

Ebastine is a novel histamine H1 receptor antagonist that combines potency with a rapid onset (fast absorption) and long duration (slow elimination) of action, at least partially mediated via the formation of an acid metabolite (carebastine) that is even more potent as an antihistamine. It shows clear selectivity for histamine H1 as opposed to H2 receptors, has moderate activity against other potential mediators of allergic phenomena such as leukotriene C4 and platelet-activating factor, and is clearly effective against anaphylactic reactions resulting from exposure of suitably sensitised tissues or animals to antigen. By contrast, ebastine has negligible activity against acetylcholine (no atropine-like adverse effects on secretions and visual accommodation) and only poorly penetrates the blood-brain barrier (no sedative adverse effects). Ebastine is without effects on the central nervous and cardiovascular systems, even after oral administration of high doses, and does not interact pharmacologically with a wide range of other drugs covering most areas of potential coadministration. Furthermore, ebastine showed no clinically relevant effects in a complete set of regulatory-required toxicity tests (including acute, chronic, reproductive, mutagenic and carcinogenic protocols) at doses giving blood concentrations representing high multiples of clinical exposure. In conclusion, ebastine has a preclinical profile indicative of an excellent therapeutic ratio of desired effects to undesired effects.

Animals↗
PubMed1995

Specific therapeutic group age-sex related prescribing units (STAR-PUs): weightings for analysing general practices' prescribing in England.

OBJECTIVES: To derive cost comparators for prescribing by English general practitioners in eight specific therapeutic groups, based on age-sex related weightings, and to confirm, from a new dataset, earlier age-sex weightings for overall prescribing (ASTRO-PUs). DESIGN: Calculations based on one year's prescribing data from selected practices using AAH Meditel software, held on MediPlus by Intercontinental Medical Statistics (IMS, UK and Ireland), and research practices using VAMP software, held on the General Practice Research Database. SETTING: 112 English practices with 739,672 patients and 510 British practices with 3,126,570 patients. MAIN OUTCOME MEASURES: Cost based weightings for 18 age-sex groups and for temporary residents for eight leading specific therapeutic groups and for prescribing overall. RESULTS: The two datasets were similar in age distribution and in the way that prescription numbers were distributed by age-sex band in each therapeutic group. The cost based weightings for specific therapeutic groups showed great variation in the use of these groups for patients in different age-sex groups. When these weightings were applied to the prescribing of practices in two family health services authorities they differed in their power to predict prescribing costs: for cardiovascular and gastrointestinal drugs predictive power was particularly high; for drugs for infections it was particularly low, since these are widely used at all ages and for both sexes. Cost based weightings for overall prescribing derived from the IMS data were similar to those of the ASTRO-PU system even though they were derived by different methods from different datasets. CONCLUSIONS: The weightings (STAR-PUs) offer a sound basis for cost comparisons at the therapeutic group level. Cost-based weightings for overall prescribing derived from the IMS data were reassuringly similar to those of the existing ASTRO-PU system.

Adolescent↗
PubMed1995

Switches in expression of Plasmodium falciparum var genes correlate with changes in antigenic and cytoadherent phenotypes of infected erythrocytes.

Plasmodium falciparum expresses on the host erythrocyte surface clonally variant antigens and ligands that mediate adherence to endothelial receptors. Both are central to pathogenesis, since they allow chronicity of infection and lead to concentration of infected erythrocytes in cerebral vessels. Here we show that expression of variant antigenic determinants is correlated with expression of individual members of a large, multigene family named var. Each var gene contains copies of a motif that has been previously shown to bind diverse host receptors; expression of a specific var gene correlated with binding to ICAM-1. Thus, our findings are consistent with the involvement of var genes in antigenic variation and binding to endothelium.

Amino Acid Sequence↗
PubMed1995

Cloning, expression, and chromosomal location of SHH and IHH: two human homologues of the Drosophila segment polarity gene hedgehog.

The hedgehog genes encode signaling molecules that play a role in regulating embryonic morphogenesis. We have cloned and sequenced human cDNA copies of two of these genes, SHH and IHH. The SHH clone includes the full coding sequence and encodes a protein 92.4% identical to its murine homologue. The IHH clone is 89% complete and encodes a protein 94.6% identical to its murine homologue. IHH is expressed in adult kidney and liver. SHH expression was not detected in adult tissues examined; however, it is expressed in fetal intestine, liver, lung, and kidney. SHH mapped to chromosome 7q and IHH to chromosome 2 by PCR with DNA from a panel of rodent-human somatic cell hybrids. To identify the chromosomal location of SHH more precisely, a P1 genomic clone of SHH was isolated. This phage contained a CA repeat sequence tagged site that was used to map SHH relative to a polysyndactyly disease locus, using DNA prepared from affected and unaffected members of a large pedigree. SHH is closely linked, but distinct from the polysyndactyly disease locus at 7q36 (maximum lod score = 4.82, theta = 0.05) tightly linked to the EN2 locus. The murine homologues Shh, Ihh, and Dhh were mapped using (C57BL/6J x Mus spretus)F1 x C57BL/6J interspecific backcross. Shh mapped to a position 0.6 cM distal to En2 and 1.9 cM proximal to Il6 on mouse chromosome 5. This location is closely linked but distinct from the murine limb mutation Hx and syntenic to human chromosome 7q36.

Amino Acid Sequence↗
PubMed1995

Use of narrow-bore high-performance liquid chromatography-diode array detection for the analysis of intermediates of the biological degradation of 2,4,6-trinitrotoluene.

A single method was developed for the separation and quantitation of hexahydro-1,3,5-trinitro-1,3,5-triazine, 2,4,6-trinitrotoluene (TNT), and most of the known and suspected biodegradation intermediates of TNT by RP-HPLC and diode array detection. The known biodegradation intermediates of TNT analyzed were 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, 2,6-diamino-4-nitrotoluene, 2,4-diamino-6-nitrotoluene, 2,4,6-triaminotoluene, 2,2',6,6'-tetranitro-4,4'-azoxytoluene, and 4,4',6,6'-tetranitro-2,2'-azoxytoluene. The suspected biodegradation intermediates of TNT included 1,2,3-benzenetriol (pyrogallol), 1,3,5-benzenetriol (phloroglucinol), 2-methyl-1,3,5-benzenetriol (methyl phloroglucinol) and 4-methylphenol (p-cresol). Mobile phases consisting of aqueous buffers adjusted to three different pH values in a gradient with acetonitrile were examined for their efficiency in separating the intermediate compounds and for the minimization of speciation of the ionizable intermediates (e.g. 2,4,6-triaminotoluene). A final aqueous buffer pH of 3.2 was selected to minimize the interference to the separation caused by 2,4,6-triaminotoluene speciation. Solvent consumption was minimized by the use of a narrow-bore column. All of the known reduction products as well as p-cresol and methyl phloroglucinol were identified in culture supernatants from TNT-degrading cultures while pyrogallol and phloroglucinol were not.

Biodegradation, Environmental↗
PubMed1995

Deletion of chromosome 2q24-q31 causes characteristic digital anomalies: case report and review.

We describe a newborn boy with multiple anomalies, including bilateral split foot and an interstitial deletion of chromosome 2 (q24.2-q31.1). Four additional cases in 2 families involving similar deletions have been reported. Bilateral digital anomalies of hands and feet were seen in all 5 cases, including a wide cleft between the first and second toes, wide halluces, brachysyndactyly of the toes, and camptodactyly of the fingers. Other common manifestations have included postnatal growth and mental retardation, microcephaly, down-slanting palpebral fissures, micrognathia, and apparently low-set ears. Bilateral digital anomalies were reported in 22 of 24 cases with deletions including at least part of region 2q24-q31. Digital anomalies were not prevalent in 18 patients with deletions of chromosome 2q not overlapping 2q24-q31. 2q31.1 appears to be the common deleted segment in all cases with significant digital anomalies, which implies the existence of one or more genes involved in distal limb morphogenesis in this region. HOXD13 and EVX2, located in the proximity of 2q31, were not deleted in our patient by Southern analysis. Bilateral digital malformations of the hands and feet associated with other anomalies should be evaluated by chromosome analysis focused at the 2q24-q31 region.

Abnormalities, Multiple↗
PubMed1995

Midazolam reduces vomiting after tonsillectomy in children.

The purpose of this study was to assess the effect of midazolam on vomiting after tonsillectomy in children. We compared 215 children aged 1.5-14 yr undergoing tonsillectomy or adenotonsillectomy under general anaesthesia with nitrous oxide and halothane. In a double-blind fashion the subjects were administered either placebo or midazolam 75 micrograms.kg-1 iv after induction of anaesthesia. After the operation, the number of emetic episodes and the length of stay in hospital were recorded. The groups were similar with respect to age, weight, sex, mode of induction, duration of anaesthesia, surgical procedure, opioid administration and length of stay in the PAR and the Day Care Surgical Unit. The 108 midazolam-treated children had a lower incidence (42% vs 57%) of vomiting than the placebo group, P < 0.02. The placebo group had a higher incidence (9% vs 2%) of unscheduled admissions to hospital due to nausea and vomiting, P < 0.05. It is concluded that midazolam administered intravenously to children intraoperatively reduces vomiting after tonsillectomy.

Adenoidectomy↗
PubMed1995

Nitrous oxide does not increase vomiting in children after myringotomy.

The aim of this study was to establish whether nitrous oxide has a clinically important effect on postoperative vomiting in children after myringotomy. We studied 320 healthy children of ages 0.5-13 yr undergoing elective myringotomy and tube insertion. Induction and maintenance of anaesthesia were randomized to inhalation with either 70% N2O/30% O2/halothane or 100%O2/halothane. Surgical technique and postoperative management were not influenced by this study. Vomiting in the recovery room (PAR) and Day Care Surgical Unit (DCSU) was recorded by nurses unaware of the anaesthetic technique. Parents were contacted 24-48 hr after surgery to ascertain the incidence of vomiting after discharge. The groups were similar with respect to demographic data, except that the anaesthesia time was greater among the 158 patients in the N2O-treated group (11 +/- 4 vs 12 +/- 4 min, mean +/- SD). The incidence of vomiting was 13% in both groups. Most of the 42 patients that had emesis only vomited once or twice. The incidence of vomiting was not altered by sex (13% vs 13%) or duration of anaesthesia. The incidence of vomiting increased with increasing age. The children aged less than 3 yr vomited 4% of the time, those aged 3-5 vomited 11% of the time, those aged 6-8 yr vomited 17% of the time, while the incidence of vomiting among those aged 9-13 yr was 31%. Vomiting prolonged the postoperative hospital stay from 75 to 92 min, P < 0.001, ANOVA. In summary, we have been unable to demonstrate that N2O induces vomiting by children after a brief general anaesthetic for myringotomy.

Adolescent↗
PubMed1995

Oral ondansetron decreases vomiting after tonsillectomy in children.

Vomiting is a common, unpleasant aftermath of tonsillectomy in children. Intraoperative intravenous ondansetron (OND) reduces vomiting after this operation. Our double-blind, placebo-controlled, randomized investigation studied the effect of the oral form of OND on vomiting after outpatient tonsillectomy in children. We studied 233 healthy children age 2-14 yr undergoing elective tonsillectomy. Subjects were given placebo (PLAC) or OND 0.1 mg.kg-1 rounded off to the nearest 2 mg one hr before surgery. Anaesthesia was induced with either propofol or halothane/N2O. Vecuronium 0.1 mg.kg-1 was administered at the discretion of the anaesthetist. Anaesthesia was maintained with halothane/N2O, 50 micrograms.kg-1 midazolam iv and 1-1.5 mg.kg-1 codeine im. At the end of surgery, residual neuromuscular blockade was reversed with neostigmine and atropine. All episodes of in-hospital emesis were recorded by nursing staff. Rescue antiemetics in the hospital were 1 mg.kg-1 dimenhydrinate iv for vomiting x 2 and 50 micrograms.kg-1 droperidol iv for vomiting x 4. Parents kept a diary of emesis after discharge. Postoperative pain was treated with morphine, codeine and/or acetaminophen. The two groups were similar with respect to demographic data, induction technique and anaesthesia time. Oral OND (n = 109) reduced postoperative emesis from 54% to 39%, P < 0.05. This effect was most dramatic in-hospital, where 10% of the OND-patients and 30% of the PLAC-group vomited, P < 0.05. The OND-subjects required fewer rescue antiemetics, 7% vs 17%, P < 0.05. In conclusion, oral ondansetron decreased the incidence of vomiting after outpatient tonsillectomy in children.

Administration, Oral↗