Search PubMed⌕ Search

Biomedical subjects

L Daniels

Publications and source records attributed to L Daniels.

At least 37 records · Page 2Linked to original sources
PubMed1997

The Centre for Palliative Care Education and Research.

This article describes the role and function of the Centre for Palliative Care Education and Research at the University of Central England in Birmingham. The authors describe the development of the centre, which is a multidisciplinary venture in collaboration with Cancer Relief Macmillan Fund and palliative care providers throughout the west Midlands. Current educational and research initiatives are identified and some future challenges indicated.

Academies and Institutes↗
PubMed1997

Presence of F420-dependent glucose-6-phosphate dehydrogenase in Mycobacterium and Nocardia species, but absence from Streptomyces and Corynebacterium species and methanogenic Archaea.

A range of organisms known to contain F420 or to be relatives of mycobacteria were examined for F420-dependent glucose-6-phosphate dehydrogenase (FGD) and NADP-dependent glucose-6-phosphate dehydrogenase (NADP-G6PD) activities. All free-growing Mycobacterium species examined (including a virulent Mycobacterium tuberculosis strain) had FGD activities of 0.014-0.418 mumol min-1 mg protein-1, and NADP-G6PD activities of 0.013-0.636 mumol min-1 mg-1. Armadillo-grown Mycobacterium leprae had FGD activity of 0.008 mumol min-1 mg-1, but no detectable NADP-G6PD activity. Nocardia species also had FGD activity (0.088-0.154 mumol min-1 mg-1). Streptomyces and Corynebacterium species had no FGD, but had NADP-G6PD. Methanogenic Archaea had neither activity.

Corynebacterium↗
PubMed1997

The use of breastmilk in a neonatal unit and its relationship to protein and energy intake and growth.

OBJECTIVE: A nutritional audit was performed to determine whether current feeding regimes were achieving nutritional goals and to evaluate the use of breastmilk (BM) in a neonatal unit (NNU). METHODS: All fluid consumed or infused daily was documented with daily weight and weekly length and head circumference measurements in 90 preterm infants (gestational age 30.1 +/- 2.6 weeks) while in the NNU for 60 +/- 27 days. Daily protein and energy intakes were calculated using values for South Australian preterm BM. RESULTS: Parenteral nutrition provided 85% of the daily energy in week 1 falling to 11% by week 6. Ninety per cent of infants received some of their mother's BM and 62% were discharged at least partially breastfed. Protein and energy intakes were 1.03 +/- 0.35 g and 55 +/- 10 kcal/kg/day in week 1, increasing to 2.52 +/- 0.60 g and 109 +/- 15 kcal/kg per day by week 4. Protein intake correlated with weight gain (r2 = 0.39). Weight gain was 14.0 +/- 2.0 g/kg per day and z-scores for weight declined from -0.25 on admission to -1.22 on discharge, P < 0.0001. When infants were divided into two groups comprising those who received BM or formula as their predominant enteral feed, growth and protein intake (but not energy intake) were lower in the BM-fed infants. However, enteral feeds were tolerated earlier and more quickly in those infants receiving predominantly BM. CONCLUSION: Energy requirements were readily met using current feeding regimes for preterm infants but protein intakes were marginal. Mothers of preterm infants had similar breastfeeding rates to mothers of term infants in South Australia. The long-term effects of the lower growth rates of preterm infants fed predominantly BM compared with those fed predominantly formula are unknown and need be balanced against the benefits of BM.

Analysis of Variance↗
PubMed1997

Selenium status of preterm infants: the effect of postnatal age and method of feeding.

Indicators of selenium (Se) status were measured in a longitudinal study of 63 preterm and 46 term infants. Se levels in both groups were similar in the first few days of life. Preterm infants fed parenteral nutrition (PN) for several weeks developed very low plasma Se levels (< 10 micrograms/l). In those receiving either breast milk or formula in conjunction with PN, plasma Se also declined over the first 6 weeks. In the breastfed term infants plasma levels increased by 50%, but there was no increase in the term formula-fed group. In healthy preterm infants who received mainly breast milk, plasma Se concentrations remained constant at newborn levels and were below those of breastfed term infants at 6 weeks. Erythrocyte GSHPx activity did not reflect plasma Se or Se intake. In conclusion, the type of feeding, and hence Se intake, influenced plasma Se concentration in preterm infants. Provision of enteral feeding in conjunction with PN was unable to prevent a decline in plasma Se and at 6 weeks levels were well below those of the reference breastfed term infants.

Age Factors↗
PubMed1996

Si-face stereospecificity at C5 of coenzyme F420 for F420-dependent glucose-6-phosphate dehydrogenase from Mycobacterium smegmatis and F420-dependent alcohol dehydrogenase from Methanoculleus thermophilicus.

Coenzyme F420 is a 5-deazaflavin. Upon reduction, 1,5-dihydro-coenzyme F420 is formed with a prochiral center at C5. In this study we report that the F420-dependent glucose-6-phosphate dehydrogenase from Mycobacterium smegmatis and the F420-dependent alcohol dehydrogenase from Methanoculleus thermophilicus are Si-face stereospecific with respect to C5 of the 5-deazaflavin. These results were obtained by following the stereochemical course of the reversible incorporation of 3H into F420 from tritium-labeled substrates. Our findings bring to eight the number of coenzyme-F420-dependent enzymes shown to be Si-face stereospecific. No F420-dependent enzyme with Re-face stereospecificity is known. This is noteworthy since coenzyme F420 is functionally similar to pyridine nucleotides for which both Si-face and Re-face specific enzymes have been found.

Alcohol Dehydrogenase↗
PubMed1996

Isolation and characterization of a copper-resistant methanogen from a copper-mining soil sample.

A copper-resistant methanogen for which the CuSO4 MICs were approximately 2- to 36-fold higher than those for other methanogens tested was isolated from a copper-mining area in the upper peninsula of Michigan. The rod-shaped methanogen used H2-CO2 or formate, but not acetate or methanol, as a growth substrate. Standing incubation with H2-CO2 medium resulted in a mat-like surface growth, dependent on the presence of hydrogen. The presence of 1 mM cupric salt resulted in longer filamentous and intertwined cells. Antigenic fingerprinting, 16S rRNA gene analysis, morphology, and substrate use suggest that the new isolate is a novel strain of Methanobacterium bryantii that is able to use formate.

Antigens, Bacterial↗
PubMed1996

Purification of a novel coenzyme F420-dependent glucose-6-phosphate dehydrogenase from Mycobacterium smegmatis.

A variety of Mycobacterium species contained the 5-deazaflavin coenzyme known as F420. Mycobacterium smegmatis was found to have a glucose-6-phosphate dehydrogenase that was dependent on F420 as an electron acceptor and which did not utilize NAD or NADP. The enzyme was purified by ammonium sulfate fractionation, phenyl-Sepharose column chromatography, F420-ether-linked aminohexyl-Sepharose 4B affinity chromatography, and quaternary aminoethyl-Sephadex column chromatography, and the sequence of the first 26 N-terminal amino acids has been determined. The response of enzyme activity to a range of pHs revealed a two-peak pattern, with maxima at pH 5.5 and 8.0. The apparent Km values for F420 and glucose-6-phosphate were, respectively, 0.004 and 1.6 mM. The apparent native and subunit molecular masses were 78,000 and approximately 40,000 Da, respectively.

Glucosephosphate Dehydrogenase↗
PubMed1996

Randomised clinical trial of parenteral selenium supplementation in preterm infants.

AIM: To determine whether selenium supplementation of parenteral nutrition with 3 micrograms/kg/day of selenious acid is safe and effective in improving the selenium status of preterm infants. METHODS: Thirty eight preterm infants with mean (SEM) birthweight of 1171 (38) g and gestational age 29 (0.3) weeks were randomly allocated to a non-supplemented (PN-selenium, n = 19) or supplemented (PN+selenium, n = 19) group. The study began at 2.8 (0.2) (range 1-5) days of age. Term breastfed (n = 23) and formula fed (n = 8) infants were used as a reference group. RESULTS: Initially there was no difference between the preterm groups in plasma or erythrocyte selenium or glutathione peroxidase activity. Plasma selenium declined by a mean (SEM) of -13.3 (3.2) micrograms/l from 28 (4) to 16 (3) micrograms/l over the first three weeks in the PN-selenium group, but there was no fall in the supplemented infants and no net change in either group over six weeks. Over six weeks, there was a net decline in erythrocyte selenium of -106 (27) ng/g haemoglobin in the PN-selenium group, but no change in the PN+selenium group, such that at week 6 erythrocyte selenium was lower in the PN-selenium group (401 (17) ng/g haemoglobin) than the PN+selenium group (493 (25) ng/g haemoglobin). Urinary selenium was substantially higher in the PN+selenium group at each week. Initially term and preterm plasma selenium concentrations were similar, but they increased in term breastfed infants (+17 (2) micrograms/l), with both groups of preterm infants having lower plasma selenium concentrations at week 6 compared with term breastfed infants (PN-selenium 22 (3) micrograms/l; PN+selenium 23 (4) micrograms/l and term breastfed 49 (2) micrograms/l). CONCLUSIONS: Selenium supplementation of PN at 3 g/kg/day prevented depletion in newborns, but was inadequate to achieve selenium concentrations equivalent to those of breastfed term infants. Whether higher doses are more effective remains to be determined, particularly in light of the high urinary selenium secretion in supplemented infants. Selenium supplementation of both parenteral nutrition and formulas is recommended, but the optimal form and dose remain unclear.

Analysis of Variance↗
PubMed1995

Cloning, sequencing, and transcriptional analysis of the coenzyme F420-dependent methylene-5,6,7,8-tetrahydromethanopterin dehydrogenase gene from Methanobacterium thermoautotrophicum strain Marburg and functional expression in Escherichia coli.

Two methylenetetrahydromethanopterin dehydrogenases have been purified from Methanobacterium thermoautotrophicum strain Marburg: one (MTD) is coenzyme F420-dependent and oxygen-stable (Mukhopadhyay, B., and Daniels, L. (1989) Can. J. Microbiol. 35, 499-507), and the other (MTH) is coenzyme F420-independent (or hydrogenase-type) and oxygen-sensitive (Zirngibl, C., Hedderich, R., and Thauer, R. K. (1990) FEBS Lett. 261, 112-116). Based on the NH2-terminal sequence of MTD, a 36-mer oligonucleotide was designed and used to identify and clone a 6.1-kilobase pair EcoRI fragment of M. thermoautotrophicum DNA. Sequencing of this fragment revealed an 825-base pair (bp) MTD encoding gene (mtd), which was expressed in Escherichia coli yielding an enzyme that, like the native enzyme, was oxygen-stable, strictly dependent on coenzyme F420, thermostable, thermophilic, and exhibited maximum activity at an acidic pH. The amino acid sequence predicts that MTD is a hydrophobic and acidic protein with no identifiable homology to MTH (von Bunau, R., Zirngibl, C., Thauer, R. K., and Klein, A. (1991) Eur. J. Biochem. 202, 1205-1208), but comparisons with coenzyme F420 utilizing enzymes revealed a conserved region at the NH2 terminus of MTD that could correspond to the ability to interact with coenzyme F420. The mtd transcript was approximately 900 nucleotides long and initiated 8 bp upstream of the translation initiation codon and 22 bp downstream from an archaeal promoter sequence. The mtd coding sequence was followed by several poly(dT) sequences and an inverted repeat that could be transcription termination signals.

Amino Acid Sequence↗
PubMed1995

Rapid large-scale growth of Helicobacter pylori in flasks and fermentors.

We developed procedures for large-scale cultivation of Helicobacter pylori in flasks and fermentors. Flasks incubated closed under a microaerophilic gas phase with a cotton plug covered by a plastic bag, followed by removal of the bag after 8 h, gave excellent growth. Growth in a 10-liter fermentor led to excessive foaming if the medium was sparged with gas; silicone- or polyglycol-based antifoaming agents were severely inhibitory. Use of fermentor surface gassing, first with a microaerophilic 6% oxygen gas mixture, then with air, and then with 95% oxygen, allowed the culture to grow to an A600 of 2.5 in < 24 h. This method was modified for scale-up to a 100-liter fermentor.

Culture Media↗
PubMed1995

Purification of the copper response extracellular proteins secreted by the copper-resistant methanogen Methanobacterium bryantii BKYH and cloning, sequencing, and transcription of the gene encoding these proteins.

When the copper-resistant methanogen Methanobacterium bryantii BKYH was exposed to 1 mM Cu(II), it secreted approximately fourfold increased levels of three proteins, copper response extracellular (CRX) proteins. The members of the CRX protein trio had apparent molecular masses of 40.8, 42.3, and 42.9 kDa and were purified together from the culture supernatant and separated from each other by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The N-terminal amino acid sequences of the three proteins were essentially identical, and antibodies raised against one of the trio reacted with all three proteins and with three other intracellular proteins with slightly higher molecular weights. The N-terminal amino acid sequence of one of these larger proteins was different from that of the secreted CRX proteins. The gene crx, which encodes the CRX proteins, was cloned and sequenced, and crx transcription was characterized. The crx sequence predicts that the encoded polypeptide is synthesized as a precursor with an N-terminal leader peptide, containing 28 amino acid residues, that is removed during the extracellular secretion of the CRX proteins. Transcription was initiated 274 bp upstream from the crx gene, producing an approximately 1.4-kb monocistronic transcript that was present in M. bryantii BKYH cells under all growth conditions but that increased approximately fourfold in vivo in response to Cu addition. The CRX proteins appear to be glycosylated, since they react with concanavalin A and neuraminidase, and to be the products of one gene that have different levels of posttranslational glycosylation. This is supported by very similar chromatographic and electrophoretic properties, identical N-terminal amino acid sequences, immunological cross-reactivities, and the detection of only one crx-related sequence by Southern blotting. Western blots (immunoblots) showed no evidence for CRX proteins in cell lysates of several other Methanobacterium strains.

Amino Acid Sequence↗
PubMed1994

Synaptic targeting domains of synapsin I revealed by transgenic expression in photoreceptor cells.

Synapsins are abundant nerve terminal proteins present at all synapses except for ribbon synapses, e.g. photoreceptor cell synapses. Multiple functions have been proposed for synapsins, including clustering of synaptic vesicles and regulation of synaptic vesicle exocytosis. To investigate the physiological functions of synapsin and to ascertain which domains of synapsin are involved in synaptic targeting in vivo, we expressed synapsin Ib and its N- and C-terminal domains in the photoreceptor cells of transgenic mice. In these cells synapsin Ib is targeted efficiently to synaptic vesicles but has no significant effect on the development, structure or physiology of the synapses. This suggests that synapsin I does not have dominant physiological or morphoregulatory functions at these synapses. Full-length synapsin Ib and the N-terminal domains of synapsin Ib but not its C-terminal domains are transported to synapses, revealing that the molecular apparatus for synaptic targeting of synapsins is also present in cells which form ribbon synapses that normally lack synapsins. This apparatus appears to utilize the conserved N-terminal domains that are shared between all synapsins.

Animals↗
PubMed1994

Levels of psychopathology at hospital admission and discharge: the Million Clinical Multiaxial Inventory as a prognostic measure.

This study compares two pathological personality disorder scales and two severe clinical syndrome scales from the Millon Clinical Multiaxial Inventory in relation to clinical change from admission to discharge on the major dimensions of the Brief Psychiatric Rating Scale. For a sample of 52 inpatients, 17 with schizophrenia, 27 with major depression, and 8 with bipolar (manic) disorder, we investigated the prognostic utility of these Millon scales for identifying clinical improvement. Findings indicated that, while the Millon scales identified admission levels of psychopathology on three Brief Psychiatric Rating Scales, the Millon inventory predicted clinical improvement on only the brief rating of Thinking Disturbance. These findings are considered in light of prognosis as a clinical research question that is distinct from diagnostic discrimination and case identification.

Adult↗
PubMed1994

Localization of Rab5 to synaptic vesicles identifies endosomal intermediate in synaptic vesicle recycling pathway.

After exocytosis, synaptic vesicles rapidly endocytose and recycle but little is known about the molecular mechanisms involved. Rab5 is a ubiquitous low molecular weight GTP-binding protein required for endosomal fusion in fibroblasts. We have now raised polyclonal and monoclonal antibodies to rat Rab5 and show that in rat brain, Rab5 is a major synaptic vesicle protein. Immunoisolation of vesicular organelles from brain with antibodies to either Rab3A and Rab5 as small GTP-binding proteins or with synaptophysin as general synaptic vesicle marker demonstrates that there are overlapping populations of synaptic vesicles containing either Rab5 or Rab3A or both, suggesting a stage-specific association of these low-molecular weight GTP-binding proteins with synaptic vesicles. Our data provide the first biochemical evidence that synaptic vesicle recycling involves an endosomal intermediate similar to that of the receptor-mediated endocytosis pathway.

Amino Acid Sequence↗
PubMed1992

Effect of temperature on the spectral properties of coenzyme F420 and related compounds.

The uv-visible spectra of 7,8-didemethyl-8-hydroxy-5-deazaflavin-5'-phosphoryllactyl glutamate (coenzyme F420), a naturally occurring 5-deazaflavin derivative, in three different buffers changed with a rise in temperature; the effect on the extinction coefficient at 420 nm (epsilon 420) was as follows: In phosphate-buffered solutions at pH less than 7.5, the epsilon 420 increased (at pH 5.0 for a temperature shift from 15 to 60 degrees C, delta epsilon 420 was +87%), but between pH 7.5 and 8, epsilon 420 changed very little. At pH greater than 8.0 in phosphate- or borate-buffered solutions, epsilon 420 decreased slightly. In morpholineethanesulfonic acid (Mes)-buffered F420 solutions at pH 5 and 5.5, epsilon 420 changed very little, whereas at pH 6-8, the epsilon 420 decreased. Absorbance of F420 at 401 nm in phosphate buffer at pH 5 to 9 was not significantly affected by temperature. Changes in epsilon 420 due to temperature change corresponded to changes in the pKa of 8-OH of the deazaflavin molecule; studies with adenylated F420 showed that the 8-OH of F420 was responsible for these changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗