bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of atypical symptoms of gastro-oesophageal reflux to antireflux surgery
Authors: Farrell T M , Richardson W S , Trus T L , Smith C D , Hunter J G
Published: March 2003

Background

Atypical manifestations of gastro-oesophageal reflux (GOR) include asthma, chest pain, cough and hoarseness. The effectiveness of antireflux surgery for these symptoms is uncertain. The present study compared symptomatic response rates for typical and atypical GOR symptoms after fundoplication.

Methods

Between October 1991 and January 1998, 324 patients underwent laparoscopic fundoplication at Emory University Hospital and returned postoperative questionnaires. Severity of typical (heartburn) and atypical (asthma, chest pain, cough and hoarseness) GOR symptoms was reported by patients on a 0–4 scale before surgery, and at 6 and 52 weeks after operation. Patients were stratified based on preoperative symptoms into three groups: group 1 (severe heartburn/minimal atypical symptoms), group 2 (severe heartburn/severe atypical symptoms) and group 3 (minimal heartburn/severe atypical symptoms).

Results

In group 1 (n = 173) heartburn improved in 99 per cent and resolved in 87 per cent. In group 2 (n = 95) heartburn improved in 95 per cent and resolved in 76 per cent, and atypical symptoms improved in 94 per cent and resolved in 42 per cent. In group 3 (n = 56) atypical symptoms improved in 93 per cent and resolved in 48 per cent. Although all symptoms were improved by fundoplication, resolution was more likely for heartburn than for atypical symptoms.

Conclusion

Atypical symptoms of GOR are improved by fundoplication, but symptom resolution occurs in fewer than 50 per cent of patients.
Restriction enzymes in the analysis of genetic alterations responsible for cancer progression
Authors: Jenkins G J S , Williams G L , Beynon J , Ye Z , Baxter J N , Parry J M
Published: March 2003

Background

Molecular approaches are increasingly being employed to dissect the genetic changes accompanying tumour formation. These methods can often be confusing to the non-specialist as they include complex molecular steps. This can reduce the usefulness of such molecular data to clinicians. The authors aim to aid interpretation of molecular studies in general by presenting a comprehensive review of one molecular approach, i.e. the use of restriction enzymes in molecular studies of tumour development.

Method

A review was made of the molecular studies that have employed restriction enzymes in gastrointestinal cancer research. These studies have used restriction enzymes to analyse point mutation induction, gene methylation status and the deletion of chromosomal loci. In addition, emphasis is placed on some of the important considerations for the molecular analysis of tumours that can affect the molecular data obtained.

Results

Restriction enzyme digestion has played, and continues to play, a major role in analysing the genetic changes in cancer. Many adaptations of basic restriction enzyme methodologies have enhanced the application of this approach in cancer genetics.

Conclusion

The availability of 200 different restriction enzymes, each recognizing different sequences in DNA, has been invaluable in studying cancer genetics. It is hoped that current advances in protein engineering will facilitate the creation of novel restriction enzymes with tailor-made sequence specificities. This will further improve the applicability of restriction enzymes in cancer genetics.
Treatment of advanced gastric cancer by palliative gastrectomy, cytoreductive therapy and postoperative intraperitoneal chemotherapy
Authors: Jeung H C , Rha S Y , Jang W I , Noh S H , Chung H C
Published: March 2003

Background

The treatment options for the 10–20 per cent of patients with gastric cancer who present with peritoneal dissemination are extremely limited and no standard approach exists.

Methods

The feasibility of using intraperitoneal chemotherapy to treat gastric cancer with intra-abdominal gross residual lesions after palliative gastrectomy with maximal cytoreduction was investigated. Early postoperative intraperitoneal chemotherapy started on the day of operation with 5-fluorouracil 500 mg/m2 and cisplatin 40 mg/m2 (days 1–3) over a 4-week interval.

Results

Of the 53 patients enrolled between July 1994 and December 1998, 49 were eligible. The progression-free survival (PFS) was 7 months and the overall survival was 12 months. In multivariate analysis, performance status was the only significant defining factor for PFS (P = 0·009). The predominant toxicity was neutropenia and nausea/vomiting. The relative dose intensity of 5-fluorouracil and cisplatin was 89 and 63 per cent respectively.

Conclusion

Performance status emerged as a major determining factor for prognosis and patient selection for early postoperative intraperitoneal chemotherapy in patients with advanced gastric cancer after maximally cytoreductive surgery.
Role of loops in the folding and stability of yeast phosphoglycerate kinase
Authors: Collinet Bruno , Garcia Pascal , Minard Philippe , Desmadril Michel
Published: March 2003

Yeast phosphoglycerate kinase (yPGK) is a monomeric two domain protein used as folding model representative of large proteins. We inserted short unstructured sequences (four Gly or four Thr) into the connections between secondary structure elements and studied the consequences of these insertions on the folding process and stability of yPGK. All the mutated proteins can refold efficiently. The effect per residue on stability is larger for the first inserted residue. Insertion in two long βα loops (at residue positions 71 and 129) is more destabilizing than an insertion in a short αβ loop (at residue position 89) located on the opposite side of the N‐terminal domain. The effect on stability is mainly due to a large increase of the unfolding rate rather than a decrease of the folding rate. This suggests that these connections between secondary structure elements do not play an active role in directing the folding process. Insertion into the short αβ loop (position 89) has limited effects on stability and results in the detection of a kinetic phase not previously seen with the wild‐type protein, suggesting that insertions in this particular loop do qualitatively affect the folding process without a large effect on folding efficiency. For the two long βα loops (positions 71 and 129) located in the inner surface of the N‐terminal domain, the effects on stability are possibly associated with decoupling of the two domains as observed by differential scanning calorimetry during thermal unfolding.
Identification of coenzyme M biosynthetic 2‐phosphosulfolactate phosphatase.
Authors: Graham David E. , Graupner Marion , Xu Huimin , White Robert H.
Published: March 2003

Coenzyme M (CoM; 2‐mercaptoethanesulfonic acid) is the terminal methyl carrier in methanogenesis. Methanogenic archaea begin the production of this essential cofactor by sulfonating phosphoenolpyruvate to form 2‐phospho‐3‐sulfolactate. After dephosphorylation, this precursor is oxidized, decarboxylated and then reductively thiolated to form CoM. A thermostable phosphosulfolactate phosphohydrolase (EC 3.1.3.–) catalyzing the second step in CoM biosynthesis, was identified in the hyperthermophilic euryarchaeon Methanococcus jannaschii. The predicted ORF MJ1140 in the genome of M. jannaschii encodes ComB, a Mg2+‐dependent acid phosphatase that is specific for 2‐hydroxycarboxylic acid phosphate esters. Recombinantly expressed purified ComB efficiently hydrolyzes rac‐2‐phosphosulfolactate, (S)‐2‐phospholactate, phosphoglycolate and both enantiomers of 2‐phosphomalate. In contrast to previously studied phosphoglycolate phosphatases, ComB has a low pH optimum for activity, a narrow substrate specificity and an amino acid sequence dissimilar to any biochemically characterized protein. Like other phosphatases that function via covalent phosphoenzyme intermediates, ComB can catalyze a transphosphorylation reaction. Homologs of comB are identified in all available cyanobacterial genome sequences and in genomes from phylogenetically diverse bacteria and archaea; most of these organisms lack homologs of other CoM biosynthetic genes. The broad and disparate distribution of comB homologs suggests that the gene has been recruited frequently into new metabolic pathways.
Kinetics of small molecule inhibitor binding to p38 kinase
Authors: Thurmond Robin L. , Wadsworth Scott A. , Schafer Peter H. , Zivin Robert A. , Siekierka John J.
Published: March 2003

p38 mitogen‐activated protein kinase (MAPK) (p38/p38‐α/CSBP2/RK) has been implicated in the regulation of many proinflammatory pathways. Because of this, it has received much attention as a potential drug target for controlling diseases such as rheumatoid arthritis, endotoxic shock, inflammatory bowel disease, osteoporosis, and many others. A number of small molecule inhibitors of this kinase have been described, and in this paper we have used surface plasmon resonance to directly measure and quantitate their binding to p38. Despite the relatively low molecular mass (≈ 400 Da) of these inhibitors, specific binding can be observed. For the two most potent inhibitors studied, SB 203580 and RWJ 67657, dissociation constants, Kd's, of 22 and 10 nm, respectively, were obtained. These values closely match the IC50 values observed in a cell‐based TNFα release assay implying that p38 plays a major role in TNFα release. The association and dissociation rates for the binding of these inhibitors to p38 have also been quantitated. SB 203580 and RWJ 67657 have very similar association rates of around 8 × 105m−1·s−1, and the differences in affinity are determined by different dissociation rates. The weaker binding compounds have dissociation rates similar to SB 203580, but the association rates vary by an order of magnitude or more. The direct measurement of compounds binding to p38 may help in understanding the difference between potency and efficacy for these inhibitors. This in turn may yield clues on how to develop better inhibitors.
Shifted positioning of the anticodon nucleotide residues of amber suppressor tRNA species by Escherichia coli arginyl‐tRNA synthetase
Authors: Kiga Daisuke , Sakamoto Kensaku , Sato Saori , Hirao Ichiro , Yokoyama Shigeyuki
Published: March 2003

Cytidine in the anticodon second position (position 35) and G or U in position 36 of tRNAArg are required for aminoacylation by arginyl‐tRNA synthetase (ArgRS) from Escherichia coli. Nevertheless, an arginine‐accepting amber suppressor tRNA with a CUA anticodon (FTOR1Δ26) exhibits suppression activity in vivo[McClain, W.H. & Foss, K. (1988) Science, 241, 1804–1807]. By an in vitro kinetic study with mutagenized tRNAs, we showed that the arginylation of FTOR1Δ26 involves C34 and U35, and that U35 can be replaced by G without affecting the activity. Thus, the positioning of the essential nucleotides for the arginylation is shifted to the 5′ side, by one residue, in the suppressor tRNAArg. We found that the shifted positioning does not depend on the tRNA sequence outside the anticodon. Furthermore, by a genetic method, we isolated a mutant ArgRS that aminoacylates FTOR1Δ26 more efficiently than the wild‐type ArgRS. The isolated mutant has mutations at two nonsurface amino‐acid residues that interact with each other near the anticodon‐binding site.
Isolation and characterization of a thioredoxin‐dependent peroxidase from Chlamydomonas reinhardtii
Authors: Goyer Aymeric , Haslekås Camilla , Miginiac‐Maslow Myroslawa , Klein Uwe , Le Marechal Pierre , Jacquot Jean‐Pierre , Decottignies Paulette
Published: March 2003

All living organisms contain redox systems involving thioredoxins (Trx), proteins featuring an extremely conserved and reactive active site that perform thiol‐disulfide interchanges with disulfide bridges of target proteins. In photosynthetic organisms, numerous isoforms of Trx coexist, as revealed by sequencing of Arabidopsis genome. The specific functions of many of them are still unknown. In an attempt to find new molecular targets of Trx in Chlamydomonas reinhardtii, an affinity column carrying a cytosolic Trx h mutated at the less reactive cysteine of its active site was used to trap Chlamydomonas proteins that form mixed disulfides with Trx. The major protein bound to the column was identified by amino‐acid sequencing and mass spectrometry as a thioredoxin‐dependent 2Cys peroxidase. Isolation and sequencing of its gene revealed that this peroxidase is most likely a chloroplast protein with a high homology to plant 2Cys peroxiredoxins. It is shown that the Chlamydomonas peroxiredoxin (Ch‐Prx1) is active with various thioredoxin isoforms, functions as an antioxidant toward reactive oxygen species (ROS), and protects DNA against ROS‐induced degradation. Expression of the peroxidase gene in Chlamydomonas was found to be regulated by light, oxygen concentration, and redox state. The data suggest a role for␣the Chlamydomonas Prx in ROS detoxification in the chloroplast.
Propionate CoA‐transferase from Clostridium propionicum
Authors: Selmer Thorsten , Willanzheimer Angela , Hetzel Marc
Published: March 2003

Propionate CoA‐transferase from Clostridium propionicum has been purified and the gene encoding the enzyme has been cloned and sequenced. The enzyme was rapidly and irreversibly inactivated by sodium borohydride or hydroxylamine in the presence of propionyl‐CoA. The reduction of the thiol ester between a catalytic site glutamate and CoA with borohydride and the cleavage by hydroxylamine were used to introduce a site‐specific label, which was followed by␣MALDI‐TOF‐MS. This allowed the identification of glutamate 324 at the active site. Propionate CoA‐transferase and similar proteins deduced from the genomes of Escherichia coli, Staphylococcus aureus, Bacillus halodurans and Aeropyrum pernix are proposed to form a novel subclass of CoA‐transferases. Secondary structure element predictions were generated and compared to known crystal structures in the databases. A high degree of structural similarity was observed between the arrangement of secondary structure elements in these proteins and glutaconate CoA‐transferase from Acidaminococcus fermentans.
Amidolytic activity of prostatic acid phosphatase on human semenogelins and semenogelin‐derived synthetic substrates
Authors: Brillard‐Bourdet Michèle , Réhault Sophie , Juliano Luiz , Ferrer Michèle , Moreau Thierry , Gauthier Francis
Published: March 2003

In addition to kallikrein hK3, a serine protease generally reported as PSA (prostate‐specific antigen), at least two other enzymes in human seminal plasma also cleave synthetic peptidyl substrates derived from the sequence of human semenogelins. We have identified one of these as prostatic acid phosphatase (PAP), a major component of prostatic fluid whose physiological function is unclear. The other is a high Mr basic protein present at low concentrations in seminal plasma and that remains to be characterized. PAP was purified to homogeneity from freshly ejaculated seminal plasma. Its N‐terminal sequence and its phosphatase properties (hydrolysis of para‐nitrophenylphosphate at low pH) were determined, and its inhibition by sodium fluoride measured. Both purified and commercial PAP also had amidolytic activity on peptide substrates derived from the semenogelin sequence at neutral and slightly basic pH. The kcat/Km values were in the 102−103m−1·s−1 range using fluorogenic semenogelin‐derived substrates whose peptidyl moiety included cleavage sites that had been identified ex␣vivo. PAP cleavage sites differed from those of hK3 and were mainly at P1 = Gln residues or between residues bearing hydroxyl groups. PAP amidolytic activity was poorly inhibited by all currently used wide spectrum proteinase inhibitors. Only 3–4 dichloroisocoumarin and benzamidine inhibited purified PAP. Purified human semenogelin was cleaved by purified and commercial PAP at neutral pH; the two main cleavage sites were at Tyr292 and Ser170 (semenogelin I sequence), only the former has been identified ex vivo by analysis of seminal plasma.
Leucine aminopeptidase during meiotic development
Authors: Ishizaki Takashi , Tosaka Aki , Nara Takayuki , Aoshima Narumichi , Namekawa Satoshi , Watanabe Kei , Hamada Fumika , Omori Akira , Sakaguchi Kengo
Published: March 2003

We found a leucine aminopeptidase (LAP; EC 3.4.11.1) to be abundant in meiotic prophase tissue of a basidiomycete, Coprinus cinereus. After direct purification of the aminopeptidase component from meiocytes, we cloned the gene by degenerate PCR using partial amino‐acid sequences of the purified enzyme and 5′ and 3′ RACE. It was homologous to the eukaryotic leucine aminopeptidase gene. The recombinant protein possesses the characteristic activities of a Coprinus leucine aminopeptidase (CoLAP) with a molecular mass of 52.4 kDa, and forms a homohexamer. Northern blot and spatial distribution analysis by immunohistochemical staining indicated CoLAP to be abundant in meiotic prophase cells and the supporting cells around meiocytes, but scarce in mycelium cells. Interestingly, from zygotene to pachytene, CoLAP was mostly present in supporting cells around meiocytes, but from diplotene onwards, it was plentiful in meiocytes themselves, suggesting that its expression is required to control some of the biochemical events at meiotic prophase. Moreover, the strong expression of CoLAP mRNA immediately after treatment with methyl methanesulfonate in mycelium implies that CoLAP has a role in somatic DNA repair.
Evolution of the enzymes of the citric acid cycle and the glyoxylate cycle of higher plants
Authors: Schnarrenberger Claus , Martin William
Published: March 2003

The citric acid or tricarboxylic acid cycle is a central element of higher‐plant carbon metabolism which provides, among other things, electrons for oxidative phosphorylation in the inner mitochondrial membrane, intermediates for amino‐acid biosynthesis, and oxaloacetate for gluconeogenesis from succinate derived from fatty acids via the glyoxylate cycle in glyoxysomes. The tricarboxylic acid cycle is a typical mitochondrial pathway and is widespread among α‐proteobacteria, the group of eubacteria as defined under rRNA systematics from which mitochondria arose. Most of the enzymes of the tricarboxylic acid cycle are encoded in the nucleus in higher eukaryotes, and several have been previously shown to branch with their homologues from α‐proteobacteria, indicating that the eukaryotic nuclear genes were acquired from the mitochondrial genome during the course of evolution. Here, we investigate the individual evolutionary histories of all of the enzymes of the tricarboxylic acid cycle and the glyoxylate cycle using protein maximum likelihood phylogenies, focusing on the evolutionary origin of the nuclear‐encoded proteins in higher plants. The results indicate that about half of the proteins involved in this eukaryotic pathway are most similar to their α‐proteobacterial homologues, whereas the remainder are most similar to eubacterial, but not specifically α‐proteobacterial, homologues. A consideration of (a) the process of lateral gene transfer among free‐living prokaryotes and (b) the mechanistics of endosymbiotic (symbiont‐to‐host) gene transfer reveals that it is unrealistic to expect all nuclear genes that were acquired from the α‐proteobacterial ancestor of mitochondria to branch specifically with their homologues encoded in the genomes of contemporary α‐proteobacteria. Rather, even if molecular phylogenetics were to work perfectly (which it does not), then some nuclear‐encoded proteins that were acquired from the α‐proteobacterial ancestor of mitochondria should, in phylogenetic trees, branch with homologues that are no longer found in most α‐proteobacterial genomes, and some should reside on long branches that reveal affinity to eubacterial rather than archaebacterial homologues, but no particular affinity for any specific eubacterial donor.
The presence of phosphate at a catalytic site suppresses the formation of the MgADP‐inhibited form of F1‐ATPase
Authors: Mitome Noriyo , Ono Sakurako , Suzuki Toshiharu , Shimabukuro Katsuya , Muneyuki Eiro , Yoshida Masasuke
Published: March 2003

F1‐ATPase is inactivated by entrapment of MgADP in catalytic sites and reactivated by MgATP or Pi. Here, using a mutant α3β3γ complex of thermophilic F1‐ATPase (αW463F/βY341W) and monitoring nucleotide binding by fluorescence quenching of an introduced tryptophan, we found that Pi interfered with the binding of MgATP to F1‐ATPase, but binding of MgADP was interfered with to a lesser extent. Hydrolysis of MgATP by F1‐ATPase during the experiments did not obscure the interpretation because another mutant, which was able to bind nucleotide but not hydrolyse ATP (αW463F/βE190Q/βY341W), also gave the same results. The half‐maximal concentrations of Pi that suppressed the MgADP‐inhibited form and interfered with MgATP binding were both ≈ 20 mm. It is likely that the presence of Pi at a catalytic site shifts the equilibrium from the MgADP‐inhibited form to the enzyme–MgADP–Pi complex, an active intermediate in the catalytic cycle.
Surgical approaches to the repair of cartilage defects
Authors: Shimmin A.
Published: March 2003

Traumatic defects in articular cartilage are common in the young athletic population. They may occur in association with other injuries to the knee, particularly anterior cruciate ligament disruption. We understand that both theoretically and clinically, these defects may lead to an increased incidence of ongoing painful symptoms in the short term and degenerative joint disease in the long term. The orthopedic surgeon has several options to deal with theses injuries. The choice is dependent on the size and position of the lesion in the knee and any associated pathology.

The most commonly practised methods aim to evoke a ‘repair’ response of fibrocartilage formation. This often helps in the short term, but the fibrocartilage degenerates over time, resulting in the return of symptoms.

These ‘repair’ methods can be classified as: 1. Marrow stimulation techniques– these include abrasion chondroplasty, subchondral drilling and microfracture techniques. 2. Scaffold induced repair techniques.

More recently, attempts to ‘re‐generate’ normal articular cartilage have been introduced to clinical practice. These are: 1. Mosaicplasty– autogenous osteochondral plug transplantation. 2. Autologous chondrocyte implantation (ACI)– this involves the harvest and culturing of autologous chondrocytes and then re‐implantation via injection under a periosteal or porcine collagen patch. The newest technology allow implantation of the collagen patch which has had chondrocytes cultured within its structure. The results of these autologous chondrocyte implantation show encouraging short to medium term results clinically. 3. Some orthopaedic centres have recently been advocating ‘articular cartilage paste grafting’– this is a simple technique based upon the theory that a paste of autogenous articular cartilage and subchondral bone should contain chondrocytes, stem cells and growth factors in its own scaffold.

Orthopedic surgeons await with interest the outcome of pre‐clinical work in examining the use of growth factors, scaffold technology and gene therapy in helping with the clinical problem of articular cartilage defects.
Salt spray limits the inland penetration of a coastally restricted invertebrate: a field experiment using landhoppers (Crustacea: Amphipoda: Talitridae)
Authors: Richardson A. M. M. , Swain R. , McCoull C. J.
Published: March 2003

Invertebrates from at least three major groups (crustaceans, gastropods and insects) have distributions that are restricted to within a few hundred metres of the coast, but unlike coastal plants there has been little discussion and no tests of the mechanisms that might control such distributions.

 Coastally restricted landhoppers, Austrotroides maritimus Friend, were transported inland of their natural distribution and established in enclosures at a site in far southern Tasmania. Salt (dry and in solution) was added to these enclosures to test the hypothesis that this species is confined to the coast by a requirement for salt.

 Over 5 months, A. maritimus persisted and reproduced in the dry salt treatment, but numbers remained low or declined in the other treatments.

 The addition of salt in solution did not produce the increase in numbers seen in the dry salt treatment. There was no evidence that non‐coastal species declined under the salt treatments.

 The restriction of A. maritimus to the coast is explained in terms of its dependence on a supply of ions from salt spray, rather than a resistance to conditions which other more competitive species cannot tolerate.

 This conclusion is qualified by the possibility that there may be occasional salt‐concentrating events in the coastal zone which raise the salt concentration above the tolerance levels of non‐coastal species.

 Coastal landhoppers, in Tasmania at least, are not plesiomorphic members of their genera, so their distributions appear to be secondary, rather than representing an early stage in land colonization.
Limited intersex mimicry of floral odour in Ficus carica
Authors: Grison‐Pigé L. , Bessière J.‐M. , Turlings T. C. J. , Kjellberg F. , Roy J. , Hossaert‐McKey M. M.
Published: March 2003

The mutualism between figs and pollinators is strict and pollination of female flowers occurs by deceit. Hence the chemical signal responsible for the encounter of the partners is expected to have limited variability. However, since male and female trees bloom at different times, sexual mimicry may not be necessary. The variability of floral odour blends of Ficus carica was studied between sexes, among trees and over time, as were the quantity and identity of the released compounds.

Male and female figs emitted the same compounds, but the quantities and proportions among the compounds differed.

The composition of the fig blend and the temporal pattern of emission were similar among trees of the same sex, and emission was synchronized with pollinator presence.

Composition of the blend and quantity released changed considerably over time, but at the time of maximal emission, all three compounds known to be essential to attract pollinators were released by male and female figs.

In a seasonal environment in which male and female flowers have different phenologies, selection for a strict sexual mimicry of the volatile attractants is weak. The identity of the compounds is the same for male and female figs, but their relative abundance in the blend differ.
A simple formulation of interaction between individuals competing for light in a monospecific stand
Authors: Hikosaka K. , Nagashima H. , Harada Y. , Hirose T.
Published: March 2003

A new method to evaluate the interaction between individuals competing for light in a monospecific stand is presented.

 Light intercepted by a leaf of a target individual is influenced by its own leaves and those of neighbours higher in the canopy. We assume that light intercepted by the leaf is the sum of the light that penetrates the foliage of the target and the foliage of neighbours. We define the degree of the interaction as the fraction of the intercepted light that penetrated the foliage of neighbours.

 To determine the degree of interaction, we established experimental stands of an annual, Xanthium canadense Mill., and measured light interception directly with light‐sensitive films attached to leaves. We calculated the interaction using light absorption of individuals within the stand and of those isolated from the stand. Light interception of an individual was influenced more by its neighbours’ leaves than by its own. The degree of interaction was greater in the stand of higher density.

 The method presented here may be useful in studying the role of architectural characteristics in light competition in relation to evolutionarily stable strategies of individuals in monospecific stands.
On the convertibility of different microsite light availability indices, relative illuminance and relative photon flux density
Authors: MURAOKA H. , HIROTA H. , MATSUMOTO J. , NISHIMURA S. , TANG Y. , KOIZUMI H. , WASHITANI I.
Published: March 2003

To reveal the convertibility between different indices of microsite light environment, relative photosynthetically active photon‐flux density (R‐PPFD) and relative illuminance (RI) were measured with the ratio of red light to far‐red light (R/FR) simultaneously below various types of vegetation: temperate riparian deciduous broadleaf forest, coniferous forest, mixed forest of evergreen broadleaf and coniferous trees and cool‐temperate deciduous broadleaf forest, and in rice paddy in summer.

 Within and throughout the vegetation, R‐PPFD and RI were strongly correlated, but the slopes of the regression equations significantly exceeded 1, and differed among the vegetation types and varied seasonally.

 R/FR decreased with decreasing R‐PPFD. The difference between RI and R‐PPFD increased with decreasing R/FR: the darker the microsite, the larger the ‘error’ of the evaluated light availability if RI was used.

 RI data can be converted to R‐PPFD. Conversion from RI to R‐PPFD would allow more reliable data comparisons among the different vegetation types and among studies that use different methods to measure the light environment.
The use of recombinant human TSH in the follow‐up of differentiated thyroid cancer: experience from a large patient cohort in a single centre
Authors: Giovanni Vitale , Arianna Lupoli Gelsy , Antonio Ciccarelli , Francesco Fonderico , Michele Klain , Giovanni Squame , Marco Salvatore , Giovanni Lupoli
Published: March 2003

background Periodic evaluation of serum thyroglobulin (Tg) and whole body 131I imaging (131I‐WBS) are essential in the follow‐up of differentiated thyroid carcinoma (DTC); both diagnostic modalities require stimulation by high levels of TSH. Administration of recombinant human TSH (rhTSH) is an alternative to the withdrawal of thyroid hormone therapy.

objective The aim of this study was to report our experience in the use of rhTSH for the management of patients with DTC.

patients One hundred and four patients were enrolled in the study. A dose of 10 U of rhTSH therapy was injected intramuscularly for 2 consecutive days; 24 h after the second dose of rhTSH the patients were administered 4–5 mCi of 131I and, 48 h later, WBS was performed.

results In all patients, baseline mean serum Tg and TSH levels were 2·4 ± 1·9 ng/ml and 0·0153 ± 0·0232 mIU/l, respectively. Basal Tg levels were detectable in 58 out of 104 patients. After rhTSH injection, mean serum TSH levels rose to 122·67 ± 47·36 mIU/l. Stimulated serum Tg levels increased to ≥ 5 ng/ml and the 131I‐WBS showed an uptake in 18 patients (17·4%). Among them there were three with bone metastases and one with brain metastases, who reported violent skeletal pain and a severe headache, respectively. These were caused by the growth of tumour mass of metastases induced by rhTSH administration.

conclusions The use of rhTSH avoids the debilitating effects of hypothyroidism and its use successfully promotes iodine uptake and increases the sensitivity of serum Tg testing. The risk of causing serious side‐effects recommends performing skull magnetic resonance and radionuclide bone scan in cases of suspected brain or skeletal metastases.
Allelic loss in clinically and screening‐detected primary hyperparathyroidism
Authors: Correa Pamela , Juhlin Christofer , Rastad Jonas , Åkerström Göran , Westin Gunnar , Carling Tobias
Published: March 2003

objective Parathyroid adenomas frequently harbour deletions of genomic DNA at chromosome regions 1p, 6q and 11q. In this study we related clinical characteristics in 56 patients with primary hyperparathyroidism (pHPT) to loss of heterozygosity (LOH) in these chromosome regions.

design LOH analysis was performed on 56 sporadic parathyroid tumours using a total of 18 microsatellite markers for chromosome regions 1p, 6q and 11q. LOH was identified, for either radioactive or fluorescent labelled markers, as total absence or reduction of ≥ 50% of the signal intensity of an allele in the tumour DNA vs. constitutional DNA.

patients Twenty‐one of the patients were recruited by a population‐based screening for pHPT and the remaining pHPT patients were gathered from routine clinical practice.

results In total, 27%, 23% and 23% of the tumours showed LOH at 1p, 6q and 11q, respectively. LOH at both 1p and 11q was more common in the screening‐detected pHPT patients compared to those recruited from clinical practice (38%vs. 20%; P= 0·02 and 43%vs. 11%; P= 0·001, respectively), while allelic loss at 6q was more prevalent in the latter group (11%vs. 31%; P= 0·001). No apparent relationships between LOH at 1p, 6q, and 11q and clinical characteristics, such as glandular weight, serum levels of PTH or calcium, were demonstrated. Moreover, additional LOH analysis of chromosome 1p suggested a putative parathyroid tumour suppressor gene(s) in the region between markers DS214 and D1S503, spanning approximately 6 cM.

conclusion A high frequency of LOH at 1p and 11q in tumours of screening‐detected pHPT patients is intriguing, and may suggest that inactivation of known (the MEN1 gene) and putative tumour suppressor genes at these chromosomal regions is associated with a more benign disease.
Physical activity or food intake prior to testing did not affect the reproducibility of GH secretion elicited by GH releasing hormone plus GH‐releasing hexapeptide in normal adult subjects
Authors: Popovic Vera , Pekic Sandra , Simic Mirjana , Damjanovic Svetozar , Micic Dragan , Dieguez Carlos , Casanueva Felipe F.
Published: March 2003

objective Growth hormone deficiency (GHD) in adults is a defined syndrome of which the adverse effects on different areas of body function are reversed under replacement therapy with GH. The diagnosis of GHD is controversial in adults, relying on the GH secretion elicited by the so‐called provocative tests of GH reserve. Most of the tests in use, including the widely employed insulin tolerance test, have been shown to be blunted after daily activities, such as mild exercise, heat or food intake, which makes stringent testing conditions mandatory in order to assure reproducibility. The combined administration of GH releasing hormone (GHRH) and GH‐releasing hexapeptide (GHRP‐6) is a very effective test for the diagnosis of GH deficiency in adults. In the present study, the perturbatory action of mild physical activity and food intake on the reproducibility of this combined test was assessed.

methods Seventeen healthy volunteers of both sexes were tested twice on separate occasions with the sequential administration of GHRH (90 µg i.v.) plus GHRP‐6 (90 µg i.v.) as bolus. Eleven subjects underwent the first combined test in the morning under basal conditions and the second test was performed in the afternoon of the same day after a morning of habitual working activity and after a standard lunch. Another group of six subjects underwent similar double testing in the morning and in the afternoon after morning activity followed by lunch; however, both tests were separated by a period of 6 months.

measurements GH levels were analysed by time‐resolved fluoroimmunoassay, with sampling every 15 minutes.

results The reproducibility of the GHRH + GHRP‐6 test performed on the same day was high, with the mean GH peak being 65·4 ± 8·0 µg/l in the basal state and 51·2 ± 9·6 µg/l after lunch, while the area under the curve (AUC) was 2287 ± 288 µg/l per 45 minutes in the morning and 1759 ± 350 after lunch. When a period of 6 months had elapsed between the first and the second test, the reproducibility was well maintained with a mean GH peak of 42·7 ± 6·2 µg/l in the basal state and 34·3 ± 3·6 µg/l in the after lunch test, with the AUC 1463 ± 209 and 1164 ± 106 µg/l per 45 minutes in the morning and after lunch, respectively. When analysed individually, physical activity, lunch or time elapsed between the two tests did not significantly change the GH peak in the subjects tested.

conclusions The GHRH + GHRP‐6 test of GH reserve is a highly reproducible test in adult subjects over time, and is not perturbed by common daily activities, such as mild physical exercise or food intake. Considering that stringent testing conditions are not required and the whole test may be performed in 30 minutes, it may be useful in the clinical setting for the diagnosis of GH deficiency in adults.
Dimeric inhibins in girls from birth to adulthood: relationship with age, pubertal stage, FSH and oestradiol
Authors: Crofton P. M. , Evans A. E. M. , Groome N. P. , Taylor M. R. H. , Holland C. V. , Kelnar C. J. H.
Published: March 2003

objective Inhibin B is produced by granulosa cells in small antral follicles under the influence of FSH, whilst inhibin A is produced by larger follicles and the corpus luteum. The aims of our study were to investigate how these inhibins change from birth to late adolescence in girls, to derive reference data and to explore their relation with pubertal stage, FSH, oestradiol and each other.

study design and subjects Blood samples were collected from: (a) 345 girls aged 0–18 years to obtain age‐related reference data, and (b) 80 pre‐menarcheal girls with full pubertal staging, of whom 40 were on GH treatment at the time of sampling.

measurements Dimeric inhibins A and B were measured by double antibody enzyme‐linked immunosorbent assay (ELISA), FSH by immunoradiometric assay (IRMA) and oestradiol by radioimmunoassay.

results

Median inhibin B was low until age 6 years, slightly higher from 6 to 10 years, then increased from 10 to 12 years to reach a plateau from 12 to 18 years. Inhibin A was usually detectable in girls younger than 3 months but thereafter became undetectable in most samples until after age 10 years, when median levels rose progressively to 14 years, then stabilized from 14 to 18 years. Both inhibins displayed considerable scatter about the median throughout infancy, childhood and adolescence. Girls aged 0–10 years showed a positive correlation between inhibins A and B (P < 0·0001), whereas those aged 14–18 years showed an inverse relationship (P < 0·001), indicating the onset of ovulatory cycles. Age‐related reference ranges and data for calculation of SD scores are presented. GH‐treated girls at pubertal stage B2 (but not at B1 or B3–5) had higher inhibin B and FSH levels than untreated girls and were excluded from further analysis. Both inhibins A and B increased during puberty (P < 0·0001) and were positively correlated with each other (P < 0·01). Both inhibins were also positively correlated with FSH in pre‐pubertal girls (P < 0·05) but not at pubertal stages B3–5.

conclusions Although median levels of inhibins A and B remained low until after age 10 years in girls, the increased levels of both inhibins in individual samples, together with their positive relationship with FSH, provide further evidence of sporadic follicular development throughout infancy and childhood under the influence of FSH. The increase in both inhibins during puberty and their changing relationship with FSH are in keeping with the concept of follicular growth being dependent on the duration of FSH elevation above a critical threshold rather than the degree of elevation per se.
Electrophysiological abnormalities of the atrial muscle in patients with paroxysmal atrial fibrillation associated with hyperthyroidism
Authors: Komiya Norihiro , Isomoto Shojiro , Nakao Kojiro , Hayano Motonobu , Yano Katsusuke
Published: March 2003

objective Atrial fibrillation (AF) is common in patients with hyperthyroidism. Although the choice of an antiarrhythmic agent should be based on its electrophysiological effects and the electrophysiological properties of the arrhythmia in question, the atrial electrophysiological features of AF associated with hyperthyroidism are unknown. The purposes of this study are to clarify the atrial electrophysiological abnormalities of AF with hyperthyroidism, and to propose effective therapies for AF in patients with hyperthyroidism.

subjects and design This study included 117 patients who underwent electrophysiological study and were evaluated for thyroid function: 29 patients without AF or hyperthyroidism (Group I), 78 patients with lone paroxysmal AF (Group II), and 10 patients with paroxysmal AF and hyperthyroidism (Group III). The following electrophysiological parameters were assessed and measured quantitatively: (1) the incidence of abnormal right atrial electrograms during sinus rhythm, indicating areas of altered anatomy and conduction where AF is likely to develop; (2) the atrial effective refractory period (ERP); and (3) the atrial conduction delay (CD), which is induced by early atrial premature beats close to the atrial ERP and is thought to facilitate the occurrence of AF.

results The incidence of abnormal right atrial electrograms during sinus rhythm was significantly higher in Group II (67·1%) than in Group I (20·0%, P < 0·001) and Group III (22·2%, P = 0·009). The atrial ERP was significantly shorter in Group III (187 ± 7 ms) than in Group I (215 ± 36 ms, P = 0·019) and Group II (208 ± 28 ms, P = 0·022). The atrial CD was observed in Group III as well as in Group II.

conclusions Our data indicate that the electrophysiological features of paroxysmal AF associated with hyperthyroidism are essentially different from those of lone paroxysmal AF. In patients with paroxysmal AF and hyperthyroidism, a shortening of the refractory period in association with a facilitation of the atrial CD could be expected to increase the propensity for AF, and a pre‐existent arrhythmogenic substrate might not be essential to the genesis of AF. These findings suggest that the agents that prolong the atrial ERP are effective against AF in patients with hyperthyroidism.
Influence of the CYP2D6*10 allele on the metabolism of mexiletine by human liver microsomes
Authors: Senda C. , Yamaura Y. , Kobayashi K. , Fujii H. , Minami H. , Sasaki Y. , Igarashi T. , Chiba K.
Published: March 2003

Aims  To study the influence of CYP2D6*10 on the formation of p‐hydroxymexiletine (PHM) and hydroxymethylmexiletine (HMM) using microsomes from human liver of known genotypes.

Methods
 Microsomes from human livers of genotype CYP2D6*1/*1 (n = 5), *1/*10 (n = 6) and *10/*10 (n = 6) were used in this study. The formation of PHM and HMM was determined by high‐performance liquid chromatography.

Results  The formation rates of PHM and HMM were decreased by more than 50% and 85% in CYP2D6*1/*10 and *10/*10 microsomes, respectively, compared with *1/*1 microsomes.

Conclusions  The metabolism of mexiletine to form PHM and HMM appears to be impaired to a significant extent in human liver microsomes from hetero‐ and homozygotes of CYP2D6*10.
Contribution of dihydrocodeine and dihydromorphine to analgesia following dihydrocodeine administration in man: a PK–PD modelling analysis
Authors: Webb James A. , Rostami‐Hodjegan, Amin , Abdul‐Manap Roslina , Hofmann Ute , Mikus Gerd , Kamali Farhad
Published: March 2003

Aims  It is not clear whether the analgesic effect following dihydrocodeine (DHC) administration is due to either DHC itself or its metabolite, dihydromorphine (DHM). We examined the relative contribution of DHC and DHM to analgesia following DHC administration in a group of healthy volunteers using a PK‐PD link modelling approach.

Methods  A single oral dose of DHC (90 mg) was administered to 10 healthy volunteers in a randomised, double‐blind, placebo‐controlled study. A computerized cold pressor test (CPT) was used to measure analgesia. On each study day, the volunteers performed the CPT before study medication and at 1.25, 2.75, 4.25 and 5.75 h postdose. Blood samples were taken at 0.25 h (predose) and then at half hourly intervals for 5.75 h postdose. PK‐PD link modelling was used to describe the relationships between DHC, DHM and analgesic effect.

Results  Mean pain AUCs following DHC administration were significantly different to those following placebo administration (P = 0.001). Mean pain AUC changes were 91 score. s−1 for DHC and −17 score. s−1 for placebo (95% CI = ± 36.5 for both treatments). The assumption of a simple linear relationship between DHC concentration and effect provided a significantly better fit than the model containing DHM as the active moiety (AIC = 4.431 vs 4.668, respectively). The more complex models did not improve the likelihood of model fits significantly.

Conclusions  The findings suggest that the analgesic effect following DHC ingestion is mainly attributed to the parent drug rather than its DHM metabolite. It can thus be inferred that polymorphic differences in DHC metabolism to DHM have little or no effect on the analgesic affect.
The relationship between metformin therapy and the fasting plasma lactate in type 2 diabetes: The Fremantle Diabetes Study
Authors: Davis Timothy M. E. , Jackson Denise , Davis Wendy A. , Bruce David G. , Chubb Paul
Published: March 2003

Aims  To determine (i) which factors, including metformin, are associated with the fasting plasma lactate concentration in type 2 diabetes, and (ii) whether plasma lactate is associated with haemodynamic and metabolic effects.

Methods  We measured fasting plasma lactate in 272 well‐characterized diabetic patients from a community‐based sample, 181 (67%) of whom were taking metformin with or without other therapies. Linear regression analysis was used to identify predictors, including metformin therapy, of the plasma lactate, and to investigate associations between plasma lactate and resting pulse rate and serum bicarbonate. Factor analysis assessed independent relationships between groups of cosegregating variables.

Results Metformin‐treated patients had higher plasma lactate concentrations than nonmetformin‐treated subjects (geometric mean [s.d. range] 1.86 [1.34–2.59]vs 1.58 [1.09–2.30] mmol l−1, respectively; P < 0.001). In a linear regression model, plasma glucose, BMI and metformin use (but not dose) were independently associated with plasma lactate (P ≤ 0.028); after adjustment for the former two variables, metformin‐treated patients had a mean plasma lactate 0.16 mmol l−1 greater than in subjects not taking the drug. Factor analysis revealed that plasma lactate, plasma glucose, BMI and pulse rate cosegregated but serum bicarbonate was not in this grouping.Conclusions The present results show that metformin therapy increases the fasting plasma lactate in ambulant patients with type 2 diabetes from a community‐based cohort. From associations in the data we hypothesize that this increase reflects (i) increased sympathetic activity in patients with the metabolic syndrome (ii) increased substrate (glucose) availability and (iii) a direct metformin effect.