bluuebunny/crossref_metadata_2025 huggingface dataset:
The pathogenesis of the Lesch‐Nyhan syndrome: ATP use is positively related to hypoxanthine supply to hypoxanthine guanine phosphoribosyltransferase
Authors: Harkness R. A. , McCreanor G. M. , Greenwood R.
Published: June 2005

In order to explain features of severe hypoxanthine guanine phosphoribosyltransferase (HPRT) deficiency, the Lesch‐Nyhan syndrome, a continuous supply of substrate, hypoxanthine, for the enzyme must be generated. This supply must be increased in association with increased ATP turnover.

We have shown that ATP turnover continuously supplies hypoxanthine for recycling by the enzyme HPRT and that this supply increases curvilinearly with increasing ATP turnover. The effects of increasing exercise on ATP turnover were examined using a Latin square experimental design. The outputs of hypoxanthine, xanthine, urate and creatinine were measured. The data were then examined statistically.
2‐Deoxy‐d‐glucose uptake and fatty acid content in fibroblast cultures from children with syndromic paucity of interlobular bile ducts (alagille syndrome)
Authors: Couturier M. , Lemonnier F.
Published: June 2005

2‐Deoxy‐d‐glucose (2‐DOG) uptake was studied in skin fibroblast cultures from control children and children with Alagille syndrome or syndromic paucity of interlobular bile ducts (PILBD). No significant differences in uptake were observed between patients and controls. However, as the scatter of the results was larger in the fibroblasts from patients, we attempted to establish for these patients a relationship between 2‐DOG uptake and some biochemical parameters. We observed an inverse relationship between this uptake and the levels of plasma cholesterol and phospholipids (r=−0.85). Compared to controls, 2‐DOG uptake was significantly lower in cultures from patients who had very high levels of cholesterol (P2 group), but not in cultures from patients with moderately increased levels of cholesterol (P1 group). The level of total cellular cholesterol in cultured cells from the P1 and P2 groups was not significantly different from the control level, but we found marked differences between the concentrations of fatty acids. In the cultures from patients (especially the P2 group), we observed a significant increase in total fatty acids; among the saturated fatty acids, this increase chiefly concerned the 18:0 (14%) and among the polyunsaturated then −3 fatty acids (55%). The high concentrations of 20:5, 22:5 and 22:6, which enhance membrane fluidity, might explain the decrease in 2‐DOG uptake found in the cultures from patients (P2 group) with PILBD. The nature of these abnormalities might be connected with the genetic origin of Alagille syndrome
Normal vitamin requirements in neonates and infants
Authors: Bates C. J.
Published: June 2005

Information about vitamin requirements by neonates and infants has been derived from studies of the composition of breast milk, from feed‐response trials, from the occurrence of overt deficiency in infants fed damaged milk formulae, and by extrapolation from experimental deficiency studies on adult humans and on animals. Our knowledge is far from complete, however, and dietary recommendations have been formulated for only about half the known vitamins in the UK. In the near future, studies with stable isotope‐labelled vitamins should help to define pool sizes and turnover rates that are associated with particular intakes and thus give firmer evidence about requirements.
Intestinal transport of vitamins
Authors: Rose R. C.
Published: June 2005

Animals rely on acquiring through their diet, certain micronutrients required to support metabolism that we refer to as vitamins. The water‐soluble vitamins are absorbed in the intestine only slowly by simple diffusion; specific mechanisms of transport have evolved that normally insure complete availability of each substrate to the organism. Secondary genetic errors that result in the impairment of an intestinal transport mechanism may become debilitating.
Hyperphenylalaninaemia caused by defects in biopterin metabolism
Authors: Kaufman S.
Published: June 2005

The hepatic phenylalanine hydroxylating system consists of three essential components, phenylalanine hydroxylase, dihydropteridine reductase and the non‐protein coenzyme, tetrahydrobiopterin. The reductase and the pterin coenzyme are also essential components of the tyrosine and tryptophan hydroxylating systems. Recent studies have shown that there are three distinct forms of phenylketonuria or hyperphenylalaninaemia, each caused by the lack of one of these essential components. The variant forms of the disease that are caused by the lack of dihydropteridine reductase or tetrahydrobiopterin are characterized by severe neurological deterioration, impaired functioning of tyrosine and tryptophan hydroxylases and the resultant deficiency of tyrosine‐ and tryptophan‐derived monoamine neurotransmitters in brain.
Differential diagnosis of tetrahydrobiopterin deficiency
Authors: Niederwieser A. , Ponzone A. , Curtius H. ‐Ch.
Published: June 2005

Six hundred and seventy‐three children (483 newborns and 190 older selected children) were screened for tetrahydrobiopterin (BH4) deficiency by HPLC of urine pterins and BH4 load test. One patient with GTP cyclohydrolase I deficiency, 36 patients with dihydrobiopterin synthetase (DHBS) deficiency (of which six were in the newborn and 30 in the older children) and 14 with dihydropteridine reductase deficiency (DHPR) were found. All 37 patients with defective BH4 biosynthesis responded to a BH4 load by lowering of the elevated serum phenylalanine concentration but four of 14 patients with DHPR deficiency did not. Measurement of DHPR activity in blood spots on Guthrie cards is recommended. Since subvariants of patients with BH4 deficiency exist, homovanillic acid, 5‐hydroxyindole acetic acid, pterins, phenylalanine, and tyrosine in cerebrospinal fluid should be measured for diagnosis and the control of therapy. The activity of the phosphate‐eliminating enzyme (a key enzyme in BH4 biosynthesis and part of “DHBS”) was measured in human liver and activities of approx. 1 n U (mg protein)−1 were found. In the liver biopsy of a patient with DHBS deficiency no activity (less than 3% of controls) was demonstrated.
Enzyme studies in biotin‐responsive disorders
Authors: Bartlett K. , Ghneim H. K. , Stirk H. ‐J. , Wastell H.
Published: June 2005

There appear to be at least two underlying aetiologies for combined carboxylase deficiency; firstly, a failure of biotinylation of apocarboxylases due to a mutation of holocarboxylase synthetase (EC 6.3.4.10) which results in an enzyme with a highKm with respect to biotin and secondly, a failure of biotinylation due to a lowered availability of biotin due to biotinidase deficiency (EC 3.5.1.12). In both these disorders secondary defects of all four biotin‐dependent carboxylases result which in turn causes the excretion of the metabolites characteristic of the isolated carboxylase deficiencies. In addition, both disorders respond biochemically and clinically to the administration of large amounts of biotin.
Riboflavin‐responsive defects of β‐oxidation
Authors: Gregersen N.
Published: June 2005

The key reaction in the β‐oxidation of fatty acids is the acyl‐CoA dehydrogenation, catalyzed by short chain, medium chain, and long chain acyl‐CoA dehydrogenases. Acyl‐CoA dehydrogenation reactions are also involved in the metabolism of the branched chain amino acids, where isovaleryl‐CoA and 2‐methylbutyryl‐CoA dehydrogenases are involved and in the metabolism of lysine, 5‐hydroxylysine and tryptophan, where glutaryl‐CoA dehydrogenase functions. In all of these dehydrogenation systems reducing equivalents are transported to the main respiratory chain by electron transfer flavoprotein (ETF) and electron transfer flavoprotein dehydrogenase (ETFDH), which are common to all the dehydrogenation systems. The acyl‐CoA dehydrogenation enzymes are dependent on flavin adenine dinucleotide (FAD) as coenzyme, for which riboflavin is the precursor. Patients with multiple acyl‐CoA dehydrogenation deficiencies have been found in whom the defect has been located to ETF and/or ETFDH. A few patients with multiple acyl‐CoA dehydrogenation deficiencies have been described, in whom no defects in acyl‐CoA dehydrogenases, ETF or ETFDH have been found but who respond clinically and biochemically to pharmacological doses of riboflavin. This indicates a defect related to the metabolism of FAD. An uptake defect of riboflavin or a synthesis defect of FAD from riboflavin have been excluded byin vivo andin vitro studies. A mitochondrial transport defect of FAD or a defect in the binding FAD to ETF and/or ETFDH remains possible.
Recent advances in the mechanism of pyridoxine‐responsive disorders
Authors: Fowler B.
Published: June 2005

Pyridoxine metabolism is summarised and speculation on possible defects leading to disease is made. Inherited deficiencies of PLP enzymes, which are known to respondin vivo to pharmacologic doses of pyridoxine are listed. The mechanism of pyridoxine responsiveness in homocystinuria due to cystathionine β‐synthase deficiency is discussed. There is a correlation in most (but not all) cases between the presence of residual CS activity, which is often stimulated by pyridoxal phosphate much more than control enzyme, in cultured fibroblasts and pyridoxine responsivenessin vivo. Exceptional patients have been found and are discussed in the light of more detailed studies on their cell lines. Clearly defined abnormalities of pyridoxal phosphate binding to mutant enzyme have been demonstrated and evidence of reduced intracellular stability of mutant CS and possible modulation by pyridoxal phosphate is presented. Preliminary findings suggest that the tissue level of pyridoxal phosphate achieved following pyridoxine treatment could be one other factor in determining pyridoxine responsiveness.
Vitamin E and muscle diseases
Authors: Jackson M. J. , Jones D. A. , Edwards R. H. T.
Published: June 2005

Studies of the basic biochemical mechanisms underlying muscle damage aimed at finding agents which might reduce the amount of damage occurring in muscular dystrophy and other severe myopathies have been performed. These have suggested three types of agent which might be useful for this purpose, namely calcium antagonists, phospholipase inhibitors, and antioxidants or scavengers of reactive‐free radicals. Vitamin E falls into the latter of these three categories and has been shown to reduce the amount of damage which occurs in isolated skeletal muscles following a given stress. It is suggested that, in the absence of calcium antagonists having relatively specific and effective actions on skeletal muscle or suitable inhibitors of muscle phospholipases in man, therapy with vitamin E or other antioxidants may reduce the amount of muscle damage occurring in patients with severe myopathies.
Transport of carnitine into cells in hereditary carnitine deficiency
Authors: Eriksson B. O. , Gustafson B. , Lindstedt S. , Nordin I.
Published: June 2005

Carnitine uptake has been studied in fibroblasts from a case of hereditary carnitine deficiency and in relatives. There was no evidence for carrier‐dependent uptake in cells from the patient. The mother and probably the healthy sister had an impaired uptake. The results show that the defect in this form of carnitine deficiency is an inability to establish a concentration gradient over the cell membrane.
Medium‐chain acyl‐CoA dehydrogenase deficiency: Metabolic effects and therapeutic efficacy of long‐terml‐carnitine supplementation
Authors: Treem W. R. , Stanley C. A. , Goodman S. I.
Published: June 2005

Medium‐chain acyl‐CoA dehydrogenase deficiency is a recently described inborn error of metabolism characterized by episodes of coma and hypoketotic hypoglycaemia in response to prolonged fasting. Secondary carnitine deficiency has been documented in these patients as well as the excretion in the urine of medium‐chain‐length acyl carnitine esters, such as octanoylcarnitine. Based on the potential toxicity of medium‐chain fatty acid metabolites and the beneficial responses of patients with other inborn errors of metabolism and secondary carnitine deficiency, oral carnitine has been proposed as treatment for children with medium‐chain acyl‐CoA dehydrogenase deficiency. We report the results of carefully monitored fasting challenges of an infant with this deficiency both before and after 3 months of oral carnitine therapy. Carnitine supplementation failed to prevent lethargy, vomiting, hypoglycaemia and accumulation of free fatty acids in response to fasting despite normalization of plasma carnitine levels and a marked increase in urinary excretion of acyl‐carnitine esters. Potentially toxic medium‐chain fatty acids accumulated in the plasma in spite of therapy. Based on this study of one patient, we stress that avoidance of fasting and prompt institution of glucose supplementation in situations when oral intake is interrupted remain the mainstays of therapy for medium‐chain acyl‐CoA dehydrogenase deficient patients.
Evidence for inhibition of exodus of small neutral amino acids from non‐brain tissues in hyperphenylalaninaemic rats
Authors: de Cespedes C. , Thoene J. G. , Lowler K. , Christensen H. N.
Published: June 2005

The mechanism of the depletion of several plasma amino acids in PKU has remained unexplained. In the present study, a statistically significant decrease in the plasma concentration of several amino acids was observed 2 h after the intraperitoneal injection of Phe to weanling rats. The pattern was very similar to the one observed in PKU patients. Statistically significant increases in the distribution ratios liver/plasma and, mainly, muscle/plasma ratios accompanied in most of the cases the corresponding decreases in plasma concentrations. Equimolar injection under the same conditions of the non‐insulinogenic transport system L analogue, the a(±) isomer of the 2‐amino‐norbornane‐2‐carboxylic acid, produced, in a parallel effect to Phe, statistically significant increases in the distribution ratios of Ala and Gly, and probably of Pro in muscle, as well as of Ala in liver. These results seem to indicate that the high intracellular Phe attained inhibits the exodus of small neutral amino acids through system L, causing their depletion in plasma and ultimately in the brain. This effect may be additive to the inhibition by Phe of the entry of bulky neutral amino acids at the level of the blood‐brain barrier. Further study is needed to assess the relevance of these effects to PKU.
A case of pyruvate carboxylase deficiency with later prenatal diagnosis of an unaffected sibling
Authors: Tsuchiyama A. , Oyanagi K. , Hirano S. , Tachi N. , Sogawa H. , Wagatsuma K. , Nakao T. , Tsugawa S. , Kawamura Y.
Published: June 2005

A severely mentally retarded infant with congenital lactic acidosis due to pyruvate carboxylase deficiency is reported. The patient suffered from vomiting and convulsions soon after birth and developed severe mental and motor retardation at 3 months of age.

The persistent elevation of pyruvate and lactate in both blood and cerebrospinal fluid and hyperalanaemia suggested an impairment of pyruvate oxidation. The enzyme activities of pyruvate carboxylase in both liver tissues and cultured skin fibroblasts of the patient revealed values of about 5% of controls. However, pyruvate dehydrogenase and α‐ketoglutarate dehydrogenase activities in liver tissues were within normal limits.

The patient had no response to administration of large doses of thiamine, lipoic acid and biotin, clinically and biochemically.

A prenatal diagnosis was performed in the second pregnancy and the pyruvate carboxylase activities of the cultured amniotic fluid cells obtained by amniocentesis were within normal limits.
Introduction to recombinant DNA
Authors: Scott J.
Published: June 2005

This paper describes the current state of knowledge of methods for analysing gene structure and localization. Illustrations are given of the preparation of complementary DNA libraries and their screening by positive‐negative selection, the use of synthetic oligodeoxynucleotides and the use of antibodies. Analysis of the EGF precursor is used as an example to show its close relationship to plasma membrane receptor and its homology with the LDL receptor. Analysis of cloned genome DNA by use of bacteriophage lambda or cosmids gives useful information about gene regulation and evolution. Mutations by frame shift, point or missence mutations are discussed with reference to the LDL receptor and the apolipoproteins. The techniques of gene mapping by rat‐human cell hybridization and hybridizationin situ are illustrated, again with reference to genes coding for enzymes of cholesterol metabolism, the apolipoproteins and insulin‐like growth factors. Finally the potential ofin vitro mutagenesis and the injection of cloned DNA into the fertilized mouse ovum are discussed.
Human biochemical genetics of enzyme proteins in the new age of molecular genetics
Authors: Swallow D. M. , Hopkinson D. A.
Published: June 2005

Advances in protein biochemistry and immunology have had a major impact on the biochemical and genetical analysis of human proteins and have had applications in the analysis of the primary defects in metabolic disorders, as well as in cDNA cloning. The development and expansion of somatic cell genetic techniques has complemented conventional population and family study genetic methods. A large number of mammalian proteins undergo complex processing to achieve the synthesis of the biologically active protein. Much of this processing is under genetic control. Elucidation of these complexities requires a combination of biochemical, immunological and genetical approaches to determine the nature of the events involved.
Direct DNA analysis in family studies
Authors: Malcolm S.
Published: June 2005

Restriction fragment length polymorphisms can be followed through families to track the incidence of genetic disease. Either cloned genes or anonymous DNA fragments, closely linked to the disease locus, may be used. 10 mL of blood collected into EDTA provide an excellent source of DNA and the blood is suitable for up to 3 days. In addition to gene tracking, the gene mutation itself may be studied to determine whether there is a DNA deletion.
Applications and limitations of direct DNA analysis in genetic prediction
Authors: Pembrey M. E.
Published: June 2005

Direct analysis of DNA has enormous potential for improved carrier detection or exclusion and early prenatal diagnosis in monogenic diseases. The strategy adopted in practice is determined by the fact that in most diseases allelic genetic heterogeneity precludes elucidation of the mutation in all families. Gene tracking asks the question — has a relative or fetus inherited the same relevant chromosome region as a previously affected family member? — and requires a gene‐specific or closely linked DNA probe that reveals a restriction fragment length polymorphism (RFLP) in order to do a linkage study within the family. Gene tracking is independent of allelic heterogeneity in the disease, but is limited to those families in which key relatives are heterozygous for an RFLP.
Human DNA repair defects
Authors: Arlett C. F.
Published: June 2005

A number of human genetic diseases have come to be described as being defective in DNA repair. The minimum criterion on which this assignment is based is hypersensitivity to the clastogenic or lethal action of specific DNA damaging agents. In one disease, xeroderma pigmentosum, the molecular evidence for a defect in DNA repair is unequivocal. This condition then acts as a model for dissecting others. For the other diseases the formal evidence for defects in repair is less secure or even lacking. The evidence for repair in each disease is assembled together with any methods that have been used to support the differential diagnosis or for prenatal diagnosis. Attempts to clone human DNA repair genes are in hand and may provide the necessary evidence to decide if all the putative DNA repair defective diseases are genuine.

Neoplastic disease and neurological degeneration together with immune defects are frequent clinical features linking this set of diseases, suggesting that effective DNA repair may be important in many aspects of human health.
Molecular basis of α1‐antitrypsin deficiency and its potential therapy by gene transfer
Authors: Ledley F. D. , Woo S. L. C.
Published: June 2005

The gene for α1‐antitrypsin, a serum anti‐protease, has been cloned and sequenced. The underlying mutation in the PiZ allele has been identified as a G to A conversion giving rise to the substitution of glu by lys at position 342. Preparation of specific probes has allowed prenatal diagnosis. Recombinant retroviruses containing the normal human α1‐antitrypsin gene have been constructed and used to infect NIH3T3 cells. Analysis of DNA, RNA and protein indicate that successful incorporation of the α1‐antitrypsin was achieved and that the gene was capable of being expressed. The feasibility of genetic replacement therapy has been demonstrated and further experiments justified.
Diabetes mellitus, atherosclerosis, and the 5′ flanking polymorphism of the human insulin gene
Authors: Mandrup‐Poulsen T. , Owerbach D. , Nerup J. , Johansen K. , Hansen A. Tybjærg
Published: June 2005

On the 5′ side of the human insulin gene is a highly polymorphic locus containing 2 major size classes of DNA restriction fragments which segregate in families as stable genetic elements. Fragments with an average size of about 600 base‐pairs (bp) (the ‘L‐allele’) seem to be a weak genetic marker for type 1 (insulin‐dependent) diabetes mellitus, whereas fragments of an average size of about 2500 bp (the ‘U‐allele’) have hitherto been associated with type 2 (non‐insulin‐dependent) diabetes mellitus and diabetic hypertriglyceridaemia. Recent evidence does not confirm the association between the U‐allele and type 2 diabetes. Our own studies suggest that the U‐allele is a fairly strong marker for the development of atherosclerosis with a relative risk for U‐carriers of 3.36. The U‐allele has not been associated with conventional cardiovascular risk factors such as body weight, blood pressure, or levels of blood glucose, triglycerides or lipoproteins. The putative functions of the polymorphic region in the aetiology of type 1 diabetes and atherosclerosis, and the relation of this region to other genetic markers for these disorders are not known.
Clinical aspects of congenital adrenal hyperplasia: Early diagnosis and prognosis
Authors: Hughes I. A.
Published: June 2005

The neonatal presentation of congenital adrenal hyperplasia is either virilization of females or salt loss in both sexes. Early diagnosis is based on the rapid measurement of plasma 17α‐hydroxyprogesterone. Milder forms of congenital adrenal hyperplasia can present later in life with abnormalities of somatic or sexual development. The majority of cases of congenital adrenal hyperplasia are clinically diagnosable in the first 2–3 weeks of life: the need for screening for the remaining missed cases and the late onset types remains to be established.
Biochemical aspects of congenital adrenal hyperplasia
Authors: Honour J.
Published: June 2005

The assay of 17α‐hydroxyprogesterone in blood spots on filter paper forms the basis of neonatal screening programmes to detect congenital adrenal hyperplasia (CAH) due to 21‐hydroxylase deficiency. The blood concentrations of this hormone in the neonate varies with gestation age (termv preterm), age after birth, time of day and illness. Broad reference ranges for blood spot 17α‐hydroxyprogesterone concentrations are therefore quoted for healthy term infants and these ranges are not appropriate for the interpretation of values in preterm and sick newborns. There is a risk of a false‐negative or of a false‐positive diagnosis. Many of the above difficulties may result from variations in assay performance due to changes in the pattern of steroids produced by the adrenal gland which in turn relate to morphological changes in the adrenal cortex at this age. The purpose of this presentation is to define the complex steroid milieu of the newborn human and briefly to review the factors which determine the function of the adrenal gland, since these influence the extent to which an assay for this steroid needs to be evaluated before application to neonatal screening for CAH. The data to be presented derive from the capillary column gas chromatographic analysis (GC) of steroids in urine since this provides the best method to display the overall steroid production of the organism. The GC method has itself been refined so that CAH can now be reliably diagnosed using this method, but the information from this work will also be judged for its relevance to the problems encountered in the neonatal screening for CAH by blood spot analysis.
Responses of ground vegetation species to clear‐cutting in a boreal forest: aboveground biomass and nutrient contents during the first 7 years
Authors: Palviainen Marjo , Finér Leena , Mannerkoski Hannu , Piirainen Sirpa , Starr Michael
Published: June 2005

Rapid growth of ground vegetation following clear‐cutting is important to site productivity because vegetation retains nutrients in the ecosystem and can decrease nutrient leaching prior to stand re‐establishment. Aboveground biomass, nutrient contents (N, P, K and Ca) and species composition of ground vegetation were determined 1 year before and for 7 years after clear‐cutting of a mixed forest dominated by Norway spruce [Picea abies (L.) H. Karst.] in eastern Finland. The biomass of the feather mosses [Pleurozium schreberi Brid. and Hylocomium splendens (Hedw.) B. S.& G.] and the dwarf shrubs (Vaccinium myrtillus L. and V. vitis‐idaea L.), which had dominated the ground vegetation in the mature forest, significantly decreased after clear‐cutting. However, with the exception of H. splendens, these species had recovered within 3–5 years. The biomass of Deschampsia flexuosa (L.) Trin. considerably increased soon after clear‐cutting, and Epilobium angustifolium L. appeared 3–5 years after cutting. These species contributed to the retention of nutrients not simply because of their biomass but also because of higher nutrient concentrations in their tissues. Total biomass and nutrient contents of the ground vegetation exceeded those of the pre‐cutting levels. The proportion of ground vegetation biomass and nutrient contents represented by mosses decreased after cutting, while V. myrtillus, although reduced after cutting, remained a marked nutrient sink. The results suggest that H. splendens is the most sensitive species to cutting, but the biomass of P. schreberi, V. myrtillus and V. vitis‐idaea return to initial levels soon after clear‐cutting as do the nutrient contents of ground vegetation.
Microsites for seedling establishment of subalpine conifers in a forest with moss‐type undergrowth on Mt. Fuji, central Honshu, Japan
Authors: Sugita Hisashi , Nagaike Takuo
Published: June 2005

We examined microsites for the seedling establishment of Tsuga diversifolia, Abies veitchii and Abies mariesii in a subalpine coniferous forest with moss‐type undergrowth dominated by Hylocomium splendens and Pleurozium schreberi on Mt. Fuji, a less‐snowy mountain located on the Pacific Ocean side of the central part of Honshu Island, Japan, and compared these microsites with cases in other regions of Japan with different undergrowth vegetation (herb type, dwarf‐bamboo type) under snowier conditions. L‐shaped size structures with abundant seedlings and small trees were identified for all three species. Established seedlings of T. diversifolia showed remarkable preference for elevated microsites such as fallen logs and convex ground (i.e. ground raised around trunk bases), while A. veitchii and A. mariesii indicated no significant bias toward such elevated microsites in the large seedling stage. However, the relative frequency of T. diversifolia seedlings established on flat ground reached high values of 54–77%, since the relative occupation area of the flat ground was large (85–89%). Such a large share suggests that flat ground should be regarded as the most important microsite for the seedling establishment of T. diversifolia in forests with moss‐type undergrowth. This preference trait for T. diversifolia observed with moss‐type undergrowth has not been reported in previous studies examining forests with herb‐ and dwarf bamboo‐type undergrowth, where T. diversifolia seedlings are scarce on the ground and restricted to elevated microsites. We conclude that the major microsite for T. diversifolia seedling establishment changes according to the undergrowth vegetation type: a large ground share for moss‐type undergrowth and a small ground share for herb‐ and dwarf bamboo‐type undergrowth.
Comparison principle for second order elliptic operators and applications
Authors: Tahraoui Rabah
Published: June 2005

Given two elliptic operatorsA_{1}andA_{2}, let us consider the following problems:

\begin{cases} −A_{i}u_{i} = f_{i}, & f_{i}⩾0\text{ in }\Omega , \\ u_{i}|_{\partial _{\Omega }} = 0, & i = 1,2. \end{cases}

In this work, we give some sufficient conditions ensuring the following comparison principle:

u_{1}(x)⩾u_{2}(x)\:\forall x \in \Omega .

As application, we study the behaviour, as|x|\rightarrow + \infty, of the solutionuof the problem

\begin{cases} −Au = f\: &\text{in }\mathbb{R}^{N}, \\ \lim\limits_{|x|\rightarrow + \infty }u(x) = 0. & \end{cases}

Etant donnés deux opérateurs

\begin{cases} −A_{i}u_{i} = f_{i}, & f_{i}⩾0\text{ in }\Omega , \\ u_{i}|_{\partial _{\Omega }} = 0, & i = 1,2. \end{cases}

Dans ce travail, on se propose de donner des conditions suffisantes portant surA_{i},f_{i}permettant de comparer les deux solutionsu_{1}etu_{2}:

u_{1}(x)⩾u_{2}(x)\:\forall x \in \Omega .

Comme application, nous étudions le comportement asymptotique, quand|x|\rightarrow + \infty, de la solutionudu problème suivant :

\begin{cases} −Au = f\: &\text{in }\mathbb{R}^{N}, \\ \lim\limits_{|x|\rightarrow + \infty }u(x) = 0. & \end{cases}
Expression and functional characterization of LRRC4, a novel brain‐specific member of the LRR superfamily
Authors: Zhang Qiuhong , Wang Jieru , Fan Songqing , Wang Lili , Cao Li , Tang Ke , Peng Cong , Li Zheng , Li Weifang , Gan Kai , Liu Zhongqi , Li Xiaoling , Shen Shourong , Li Guiyuan
Published: June 2005

LRRC4, a novel member of LRR superfamily thought to be involved in development and tumorigenesis of the nervous tissue, has the potential to suppress tumorigenesis and cell proliferation of U251MG cells. This study aimed at revealing the correlation between expression of LRRC4 and the maintenance of normal function and tumorigenesis suppression within the central nervous system. We systematically analyzed the expression and tissue distributions of the gene in tissues. Results showed that LRRC4 expression was limited to normal adult brain, both in human and in mouse, and exhibited a development‐regulated pattern, but was down‐regulated in brain tumor tissues and U251MG cell line. Furthermore, dynamic alterations in gene expression associated with cell cycle progression were investigated by using Tet‐on system. Results showed that LRRC4 induced a cell cycle delay at the late G1 phase, probably through the alteration of the expression of different cell cycle regulating proteins responsible for mediating G1‐S progression, such as p21Waf1/Cip1 and p27Kip1, Cdk2 and PCNA, p‐ERK1/2. These findings suggest that LRRC4 may play an important role in maintaining normal function and suppressing tumorigenesis in the central nervous system.
The maize gene space is compositionally compartimentalized
Authors: Carels Nicolas
Published: June 2005

Previous investigations by Southern hybridization of cDNA with compositional DNA fractions showed that the majority of maize genes are located in a narrow GC range of DNA fragments and that the corresponding gene space was GC‐richer than the region of the genome where zein genes are found. Here, we revisited the maize gene space using new data from the maize genome sequencing initiative. We found that the maize gene space itself is formed of two compositional compartments, i.e., a GC‐poor and a GC‐rich, characterized by a different distribution of Opie and Huck retrotransposons. The GC‐rich compartment tends to be richer in GC‐rich genes than the GC‐poor compartment. However, the gene space compartimentalization of maize is much simpler than that of human.
Seabream antiquitin: Molecular cloning, tissue distribution, subcellular localization and functional expression
Authors: Tang Wai-Kwan , Chan Chi-Bun , Cheng Christopher H.K. , Fong Wing-Ping
Published: June 2005

Subsequent to our earlier report on the first purification of antiquitin protein from seabream liver and demonstration of its enzymatic activity [FEBS Letters 516 (2002) 183–186], we report herein the cloning of its full‐length cDNA sequence. The open reading frame encodes a protein of 511 amino acids. Results of RT‐PCR indicate that antiquitin is highly expressed in both the seabream liver and kidney. Transfection studies in cultured eukaryotic cells provided further evidence that it is a cytosolic protein. Bacterial expression of the enzyme was also performed. The purified recombinant protein was demonstrated to exhibit similar kinetic properties as the native enzyme.
Glycogen synthesis in the absence of glycogenin in the yeast Saccharomyces cerevisiae
Authors: Torija María-Jesús , Novo Maite , Lemassu Anne , Wilson Wayne , Roach Peter J. , François Jean , Parrou Jean-Luc
Published: June 2005

In eukaryotic cells, glycogenin is a self‐glucosylating protein that primes glycogen synthesis. In yeast, the loss of function of GLG1 and GLG2, which encode glycogenin, normally leads to the inability of cells to synthesize glycogen. In this report, we show that a small fraction of colonies from glg1glg2 mutants can switch on glycogen synthesis to levels comparable to wild‐type strain. The occurrence of glycogen positive glg1glg2 colonies is strongly enhanced by the presence of a hyperactive glycogen synthase and increased even more upon deletion of TPS1. In all cases, this phenotype is reversible, indicating the stochastic nature of this synthesis, which is furthermore illustrated by colour‐sectoring of colonies upon iodine‐staining. Altogether, these data suggest that glycogen synthesis in the absence of glycogenin relies on a combination of several factors, including an activated glycogen synthase and as yet unknown alternative primers whose synthesis and/or distribution may be controlled by TPS1 or under epigenetic silencing.
Transfer of β subunit regulation from high to low voltage‐gated Ca2+ channels
Authors: Arias Juan Manuel , Murbartián Janet , Vitko Iuliia , Lee Jung-Ha , Perez-Reyes Edward
Published: June 2005

High voltage‐activated Ca2+ channel expression and gating is controlled by their β subunits. Although the sites of interaction are known at the atomic level, how β modulates gating remains to be determined. Using a chimeric approach, β subunit regulation was conferred to a low voltage‐activated channel. Regulation was dependent on a rigid linker connecting the α1 interaction domain to IS6. Chimeric channels also revealed a role for IS6 in channel gating. Taken together, these results support a direct coupling model where β subunits alter movements in IS6 that occur as the channel transits between closed, open, and inactivated states.
Unfolding and breakdown of insulin in the presence of endogenous thiols
Authors: Jiang Chuantao , Chang Jui-Yoa
Published: June 2005

Native insulin denatures and unfolds in the presence of thiol catalyst via disulfide scrambling (isomerization). It undergoes two transient non‐native conformational isomers, followed by an irreversible breakdown of the protein to form oxidized A‐ and B‐chain. Denaturation and breakdown of native insulin may occur under physiological conditions. At 37 °C, pH 7.4, and in the presence of cysteine (0.2 mM), native insulin decomposes with a pseudo first order kinetic of 0.075 h−1. At 50 °C, the rate increases by 5‐fold. GdnCl and urea induced denaturation of insulin follows the same mechanism. These results demonstrate that stability and unfolding pathway of insulin in the presence of endogenous thiol differ fundamentally from its reversible denaturation observed in the absence of thiol, in which native disulfide bonds of insulin were kept intact during the process of denaturation.
Efficacy of tibolone and transdermal estrogen therapy on psychological symptoms in women following surgical menopause
Authors: Baksu A. , Ayas B. , Cıtak S. , Kalan A. , Baksu B. , Goker N.
Published: June 2005

Objective: This study investigated the efficacy of tibolone and transdermal estradiol therapy on menopausal and psychological symptoms in women following surgical menopause. Method: Seventy‐five women who had undergone surgical menopause were randomized to a 6‐month double‐blind interventional study treatment with oral 2.5 mg/day tibolone, transdermal 3.9 mg/week estradiol or oral placebo. The patients were assessed using Kupperman's Scale, Hamilton Depression Rating Scale (HDRS) and Hamilton Anxiety Rating Scale (HARS) before and at the end of the 6 months of treatment. Result: Sixty‐five subjects completed the study: 23 on tibolone, 21 on transdermal estradiol and 21 on placebo. At the end of the 6 months of therapy, highly significant improvements in menopausal symptoms, depression and anxiety scores were observed in both groups (tibolone and transdermal estradiol groups) as compared with baseline values (p<0.001). However, in the placebo group, there were no significant differences on changes from baseline to the end of treatment (p > 0.05). Conclusion: These results suggest that tibolone and transdermal estradiol therapy significantly improve menopausal and psychological symptoms in women following surgical menopause.
Could lean production job design be intrinsically motivating? Contextual, configurational, and levels‐of‐analysis issues
Authors: de Treville Suzanne , Antonakis John
Published: June 2005

Are lean production jobs intrinsically motivating? More than 20 years after the arrival of lean production, this question remains unresolved. Generally accepted models of job design such as the Job Characteristics Model (JCM, (Hackman, J.R., Oldham, G.R. 1976. Motivation through the design of work: test of a theory. Organizational Behavior and Human Performance 16, 250–279.)) cannot explain the occurrence of worker intrinsic motivation in the context of lean production. In this paper, we extend the JCM to the lean production context to explain the theoretical relationship between job characteristics and motivational outcomes in lean production. We suggest that a configuration of lean production practices is more important for worker intrinsic motivation than are independent main effects, and that motivation may be limited by excessive leanness. We conclude that lean production job design may engender worker intrinsic motivation; however, there are likely to be substantial differences in intrinsic motivation under differing lean production configurations.
Molecular analysis of Continuous Plankton Recorder samples, an examination of echinoderm larvae in the North Sea
Authors: Kirby Richard R , Lindley John A.
Published: June 2005

Analysis of the biological time series of plankton samples collected by the Continuous Plankton Recorder (CPR) in the North Atlantic and North Sea has shown a regime shift in the plankton in this region. Both the distributions of planktonic organisms and their timing of occurrence in the seasonal cycle have changed and these changes appear to reflect global warming. In the North Sea the planktonic larvae of echinoderms have shown a recent dramatic increase in both relative and absolute abundance and their seasonal peak of occurrence has advanced by 47 days. The identity of the echinoderm larvae involved in this change has, however, remained equivocal. The small size of many organisms like echinoderm larvae combined with incomplete taxonomic keys hinders their visual identification and their fragility often means that useful morphological features are damaged during sampling by the CPR. Here, using new molecular methods applied to CPR samples, we show that planktonic larvae of the benthic Echinocardium
cordatum dominate the North Sea plankton. We argue that since this species benefits from mild winters and warmer waters their numerical increase in the plankton is consistent with recent climatic changes that appear to be affecting the wider ecology of this region.
Changes in appendicularian Oikopleura dioica abundance caused by invasion of alien ctenophores in the Black Sea
Authors: Shiganova Tamara
Published: June 2005

Oikopleura dioica is the only recorded appendicularian in the Black Sea. During the last two decades major changes in the O. dioica population size as well as total zooplankton community structures were recorded when invasive ctenophore species appeared in the Black Sea ecosystem. The state of the O. dioica population, before the invasion of ctenophores Mnemiopsis leidyi and Beroe ovata, is reviewed. The effect of the invasion of these ctenophores on the total zooplankton and particularly on the O. dioica standing stock is summarized from our long-term data and published information. The abundance, biomass and species composition of zooplankton greatly decreased after the ctenophore Mnemiopsis leidyi invasion due to predation by M. leidyi. Specifically, the abundance of O. dioica declined at that period. But with increasing numbers of a new invader, the ctenophore Beroe ovata, a predator of M. leidyi, in 1999, the zooplankton community began to recover. The population density of Oikopleura dioica also gradually increased to a level that was within the range of its abundance before the M. leidyi outbreak and even higher due to increasing its prey bacteria, which was provoked by the mucus released by B. ovata.
Calycophorae (Siphonophora) in the open waters of the central and southern Adriatic Sea during spring 2002
Authors: Lučić Davor , Benović Adam , Batistić Mirna , Njire Jakica , Onofri Vladimir
Published: June 2005

Twenty species of calycophoran siphonophores were identified from the central and south Adriatic Sea in spring 2002. Highest abundance and species diversity were noted at the deepest stations in the south Adriatic. Highest total abundance was found in the upper 100 m. The dominant species above 100 m were Lensia subtilis, Eudoxoides spiralis and Sphaeronectes gracilis, none of which showed diel migration. The first two species correlated significantly with the vertical abundance of microzooplankton, and the last with that of copepods. The most abundant species in the 100-400 m layer was Lensia meteori, whereas Lensia conoidea and Chlausophyes ovata were most abundant below 400 m.
Summer ichthyoplankton, food supply of fish larvae and impact of invasive ctenophores on the nutrition of fish larvae in the Black Sea during 2000 and 2001
Authors: Gordina A.D. , Zagorodnyaya Ju.A. , Kideys A.E. , Bat L. , Satilmis H.H.
Published: June 2005

Qualitative composition and abundance of both ichthyoplankton and small forms of zooplankton were evaluated by field studies in the northern (the Crimea near Sevastopol) and southern (Sinop region and TEEZ) Black Sea during the summers 2000 and 2001. A tendency of increasing the species richness, abundance of fish eggs and larvae as well as zooplankton (which is the food for fish larvae) was observed over a period of Mnemiopsis leidyi and Beroe ovata co-existence. The eggs and larvae of the Mediterranean migrants—bonito and bluefish appeared again in the coastal waters near Sevastopol, which testified to favourable conditions for the spawning and nutrition of these fish species and their larvae. Aborigen copepod Oithona nana was found in the Crimean coastal waters although earlier in the 1990s it had completely vanished. Although rare in the 1990s copepods Centropages ponticus and Paracalanus parvus appeared in inshore waters as well as Pontellids species. Observed increases in species number and abundance of both ichthyoplankton and small zooplankton (≤500 μm), which promoted survival and development of fish larvae, were attributed to reduced predatory impact of Mnemiopsis on prey zooplankton after the arrival of Beroe in the late 1990s. However, the influence of Mnemiopsis continued to be significant during the short period of its peak occurrence in late summer. When this period coincided with the appearance of fish larvae, a negative impact on their survival could be predicted due to a low concentration of food items for larvae feeding.
Metabolic enzyme activities in swimming muscle of medusae: is the scaling of glycolytic activity related to oxygen availability?
Authors: Thuesen Erik V. , McCullough Kelly D. , Childress James J.
Published: June 2005

This study compared the scaling of the glycolytic enzyme lactate dehydrogenase (LDH) and the Krebs cycle enzyme citrate synthase (CS) in the swimming muscle and tentacle tissue of the mesopelagic coronate scyphomedusa Periphylla periphylla in two populations living under different oxygen minimum layer conditions. The LDH and CS activities in these tissues of two other coronate scyphomedusae (Paraphyllina ransoni and Periphyllopsis galatheae) and the bathypelagic narcomedusa Aegina citrea were also studied. The scaling of these two enzymes along with total protein was investigated in whole organism homogenates of the surface-living scyphomedusa Aurelia labiata. Mass-specific LDH activities in swimming muscle showed positive scaling in relation to body size in Periphylla periphylla collected off California and Hawaii. Mass-specific LDH activities in tentacle tissue increased with regards to increasing mass only in specimens of P. periphylla collected off California. The LDH values of the scaling coefficient, b, in swimming muscle and tentacle were significantly higher in P. periphylla collected in the low oxygen waters off California than from those collected off the Hawaiian Islands in a higher oxygen environment. The LDH showed a significant decrease with body size in Aegina citrea swimming muscle and in Aurelia labiata whole animal homogenates. The largest species in this study, Periphyllopsis galatheae, had LDH activities similar to the smallest specimens of Periphylla periphylla. The results of this study suggest that the scaling of glycolytic activity is related to oxygen availability for P. periphylla. In Aurelia labiata, which is only exposed to episodic hypoxia, and Aegina citrea, scaling of glycolytic activity is not affected by oxygen availability.