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Biomedical subjects

K Tanner

Publications and source records attributed to K Tanner.

At least 19 recordsLinked to original sources
PubMed2004

Predicting outcome in ex-premature infants supported with extracorporeal membrane oxygenation for acute hypoxic respiratory failure.

OBJECTIVE: To identify predictors of outcome in ex-premature infants supported with extracorporeal membrane oxygenation (ECMO) for acute hypoxic respiratory failure. METHODS: Retrospective review of ex-premature infants with acquired acute hypoxic respiratory failure requiring ECMO support in the United Kingdom from 1992 to 2001. Review of follow up questionnaires completed by general practitioners and local paediatricians. RESULTS: Sixty four ex-premature infants (5-10 each year) received ECMO support, despite increased use of advanced conventional treatments over the decade. The most common infective agent was respiratory syncytial virus (85% of cases). Median birth gestation was 29 weeks and median corrected age at the time of ECMO support was 42 weeks. Median ECMO support duration was relatively long, at 229 hours. Survival to hospital discharge and to 6 months was 80%, remaining similar throughout the period of review. At follow up, 60% had long term neurodisability and 79% had chronic pulmonary problems. Of pre-ECMO factors, baseline oxygen dependence, younger age, and inpatient status were associated with non-survival (p < or = 0.05). Of ECMO related factors, patient complications were independently associated with adverse neurodevelopmental outcome and death (p < 0.01). CONCLUSIONS: Survival rates for ex-premature infants after ECMO support are favourable, but patients suffer a high burden of morbidity during intensive care and over the long term. At the time of ECMO referral, baseline oxygen dependence is the most important predictor of death, but no combination of the factors considered was associated with a mortality that would preclude ECMO support.

Acute Disease↗
PubMed1999

Mechanical sensitization of cutaneous C-fiber nociceptors by prostaglandin E2 in the rat.

While it is generally assumed that nociceptor sensitization underlies peripheral hyperalgesia, there is disagreement regarding the ability of inflammatory mediators to sensitize nociceptors to mechanical stimuli. In this in vivo electrophysiological study, mechanical threshold and response to sustained threshold and sustained suprathreshold mechanical stimuli were measured before and after intradermal administration of prostaglandin E2 (PGE2) into the receptive field of cutaneous C-fiber nociceptors in the rat. PGE2 produced a decrease in mechanical threshold and an increase in response to sustained threshold but not sustained suprathreshold mechanical stimulation. These data suggest that while inflammatory mediators produce a decrease in mechanical threshold and/or an increase in number of action potentials to sustained threshold stimuli, they do not increase the maximal response to mechanical stimuli in C-fiber nociceptors.

Animals↗
PubMed1995

Competitive reverse-transcriptase polymerase chain reaction without an artificial internal standard.

Advances in our understanding of molecular and cellular physiology necessitate that mRNA levels for specific growth factors and other rare transcripts be measured quantitatively in small samples. Conventional methods such as Northern blot analysis and solution hybridization/ribonuclease protection are not sufficiently sensitive. We now report the theory, development, and validation of a rapid and highly sensitive assay, the RNA/DNA quantitative polymerase chain reaction (RD-PCR), which uses a competitive PCR approach to measure the number of copies of a specific mRNA per cell. Total nucleic acid (RNA and genomic DNA) is isolated from cells in culture. The mRNA of interest is first reverse-transcribed with an oligomer bearing a complementary sequence specific for the mRNA at its 3'-end, and a sequence complementary to an intron of the desired gene at the 5'-end. Competitive PCR is then performed in the presence of the cDNA product and endogenous genomic DNA, with an upstream primer complementary to the exon sequence of the gene of interest, and a downstream primer complementary to the intron sequence that was tagged to the cDNA. The cell's own genomic DNA is thereby used as the internal standard. To control for the efficiency of reverse transcription, a standard curve is used in each assay. The technique was validated by comparing the quantitation of insulin-like growth factor I (IGF-I) mRNA in two human cell lines by RD-PCR and by RNase protection analysis. Both methods gave similar numbers of copies of IGF-I mRNA per cell. For accurate analysis, RNase protection required at least 10(7) cells; RD-PCR required as little as 10(2) cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1994

The two nonallelic Xenopus insulin genes are expressed coordinately in the adult pancreas.

We have previously shown that the two nonallelic insulin genes in Xenopus laevis are expressed differentially during neurulation in prepancreatic embryos (Shuldiner et al., 1991, Proc. Natl. Acad. Sci. USA 88, 7679-7683). We now examine pancreatic expression with alterations in ambient temperature, glucose administration, fasting and feeding, somatostatin analog treatment, as well as during postmetamorphic growth. Insulin I and II mRNAs were quantitated by slot blot hybridization with specific probes and were expressed as the number of copies (x 10(8)) per 5 micrograms total RNA +/- SEM. Frogs maintained at 12 degrees showed no significant changes when compared to frogs maintained at 20 degrees. There was a coordinate decrease in insulin I and II mRNA levels in frogs maintained at 29 degrees (Ins I 20, 3.41 +/- 0.34 vs Ins I 29, 2.39 +/- 0.17; Ins II 20, 2.59 +/- 0.36 vs Ins II 29, 1.67 +/- 0.09; P < 0.05). When compared to fasting animals, both insulin I and II mRNA levels decreased slightly in frogs given repeated intraperitoneal injections of glucose and in those fed ad libitum; there were no changes after a single dose of glucose or in frogs given somatostatin. When compared to young frogs (6 to 24 months), older frogs (36 months) had higher insulin I and II mRNA levels (e.g., Ins I 6mo, 2.14 +/- 0.15 vs Ins I 36mo, 3.68 +/- 0.43; Ins II 6mo, 1.21 +/- 0.06 vs Ins II 36mo, 3.26 +/- 0.38; P < 0.05). Further, there was a modest reduction in the percentage of insulin I mRNA with aging (e.g., 6 months 63.6 +/- 3.1% vs 36 months 53.9 +/- 2.7%; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

[Knowledge about and attitude to HIV/AIDS among dentists and dental assistants in Budapest, November 1992].

118 Dentists and 115 Dental Nurses opinion was evaluated about their knowledges and attitudes to HIV/AIDS problem in Budapest (Hungary) 1992 November. The frequency of false knowledges about the transmission was 5-10%. More than 70% of the asked persons changed their habits in working place and 62% of dentists and 78% of nurses uses rubber gloves. 2.5% of the dentists and 7.8% of nurses thinks they will refuse the treatment of a HIV/AIDS patient. Most informations collected the doctors from professional literature and the nurses from mass medias, the mention of postgraduate trainings was low. Above data are valid for those persons who are working in the state health care system. Data of the private practice will be collected and analysed in the future.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Ligase-free subcloning: a versatile method to subclone polymerase chain reaction (PCR) products in a single day.

Often, it is convenient to subclone polymerase chain reaction (PCR) products into a plasmid vector for subsequent replication in bacteria, but conventional subcloning methods often fail. We report a rapid and versatile method to subclone PCR products directionally into a specific site of virtually any plasmid vector. The procedure requires only four primers, does not require DNA ligase, and may be accomplished in a single day. Ligase-free subcloning is performed by incorporating into the PCR primers sequences at the 5' ends that result in PCR products whose 3' ends are complementary to the 3' ends of the recipient linearized plasmid. The PCR product and the linearized plasmid are spliced together in a second PCR reaction in which Taq polymerase extends the complementary overlapping 3' ends (ligation by overlap extension). Denaturation followed by heterologous reannealing and cyclization results in a cyclic recombinant plasmid with two nicks that may be used directly to transform competent Escherichia coli. In our hands, ligase-free subcloning is rapid, and offers many advantages over existing strategies.

Bacteriophage lambda↗
PubMed1991

RNA template-specific PCR: an improved method that dramatically reduces false positives in RT-PCR.

We report a novel modification of the reverse transcription PCR method, designated RNA template-specific PCR. With this approach, the 5' end of the first strand is tagged with a unique nucleotide sequence during reverse transcription that may then be exploited to amplify preferentially RNA-derived sequences. In our hands, RNA template-specific PCR retains the sensitivity of the traditional method, but greatly reduces the frequency of false positives, and virtually eliminates carryover contamination from PCR products amplified in previous experiments.

Animals↗
PubMed1990

Insulin receptors in developing rat liver. Receptor autophosphorylation and phosphorylation of the endogenous substrate pp120/HA4 (ecto-ATPase) in fetal and neonatal liver.

The development of insulin receptors and insulin-stimulated receptor autophosphorylation were studied in livers of prenatal and neonatal rats. Insulin receptors were present in mid-gestation, as early as day 14 in fetal development (full term is 22 days in the rat), with ligand-activated receptor kinase present. In contrast, insulin-stimulated phosphorylation of a Mr 120 kd glycoprotein derived from rat liver membranes, known as pp120/HA4 and more recently identified as ecto-ATPase, was not observed in fetal liver until day 17 of gestation. Thereafter, phosphorylation of pp120/HA4 increased throughout late gestation. The data suggest that maturation of the insulin receptor kinase occurs soon after initial appearance of the receptor in mid-gestation, but insulin-stimulated phosphorylation of endogenous substrate(s) is dependent on the appearance of specific substrates, such as pp120/HA4.

Adenosine Triphosphatases↗
PubMed1990

Use of crossover trials to obtain antihypertensive dose-response curves and to study combination therapy during the development of benazepril.

When a new drug is developed, one of the first requirements is to establish the correct dose. Unfortunately, in dose-determination studies, not enough lessons have been learned from the past. Pilot studies are often planned without sufficient statistical power, due to an insufficient number of patients and highly variable blood pressure measurements. In the development of the new angiotensin converting enzyme (ACE) inhibitor benazepril, crossover trials were used to obtain useful information. At the end of phase II of the benazepril development, a double-blind crossover study was carried out with 25 patients, and the results made it possible to redefine the 12- and 24-h effects of benazepril in comparison with placebo. Moreover, the crossover trial allowed an investigation of the biological effects of the treatment. In further work, the efficacy of 10 mg benazepril, administered once a day, was confirmed in comparison with captopril and enalapril, with a beta-risk of less than 20%. Since this crossover study yielded reliable data, and there was no carryover effect, a similar crossover design was used to study the interaction between benazepril and nifedipine. In the past, mistakes were made and many antihypertensive drugs were administered in high doses, with no further beneficial effect on blood pressure and an increased risk of side effects. Work described in this paper shows that fewer but better designed and implemented studies can improve the efficiency and value of dose-finding studies for antihypertensive drugs.

Antihypertensive Agents↗
PubMed1988

[Campylobacter pylori, gastritis and ulcer disease. Microbiological, histological and serological studies].

In a prospective study of 70 patients with epigastric pain, gastroduodenoscopy revealed gastric and/or duodenal ulcers in a total of 41 and no ulceration in the remainder. Biopsies were taken to assess the severity of gastritis and the presence of Campylobacter pylori (CP) by histology and culture. Gastritis was found in 54 patients. CP was detected in 78% of the ulcer patients and 52% of the patients without ulcer (p less than 0.05). CP was demonstrated in 83% of the histologically diagnosed cases of gastritis (all grades) but no CP was detectable in patients with normal gastric mucosa. Among the ulcer patients, CP was more frequent in those with no history of medication with nonsteroidal antiinflammatory drugs (p less than 0.01). Sera from CP-positive ulcer and gastritis patients have significantly higher levels of IgG antibodies to CP than sera from those found to be free of ulcer or gastritis. In 200 blood donors an increasing percentage of elevated CP-antibody titres were found with advancing age (50% over 60 years of age). Quantification of circulating CP antibodies, would thus seem a valuable adjunct in the diagnosis of gastritis and probably also of peptic ulcer. The data presented furnish further evidence of the high rate of association of CP and the gastritis-peptic ulcer complex.

Adult↗
PubMed1986

Glycogen metabolism in neonatal liver of the rat.

Prior to birth the fetus of the rat accumulates large quantities of hepatic glycogen, with these stores mobilized as glucose in the early postnatal period to sustain the newborn until the onset of suckling and gluconeogenesis. The liver acts to mobilize glycogen in the early neonatal period and gradually adjusts to the alternating supply of nutrients that results from the onset of a feeding cycle. Early postnatal glycogen mobilization is reflected in the decreased active form of glycogen synthase (GS), the rate-limiting enzyme of glycogenesis, and increased activation of glycogen phosphorylase (GP), the rate-limiting enzyme of glycogenolysis. Levels of smooth endoplasmic reticulum (SER)-associated synthase phosphatase and phosphorylase phosphatase activities are diminished from high prenatal levels, contributing to these changes in activation of GS and GP. With the onset of suckling at 1-4 h after birth the liver again accumulates small quantities of glycogen. The period of 6 to 12 h after birth is characterized by large scale glycogenolysis. Glycogen levels are again increased at 24 h after birth, reflecting hepatic adaptation to the onset of meal feeding.

Animals↗