bluuebunny/crossref_metadata_2025 huggingface dataset:
Antiproliferative effect of nitric oxide on epidermal growth factor‐responsive human neuroblastoma cells
Authors: Murillo‐Carretero Maribel , Ruano María José , Matarredona Esperanza R. , Villalobo Antonio , Estrada Carmen
Published: March 2003

Addition of nitric oxide (NO) donors to NB69 neuroblastoma cells produced a cGMP‐independent decrease in cell proliferation, without affecting cell viability or apoptosis. The potency of short half‐life NO donors was higher when cell proliferation was stimulated by epidermal growth factor (EGF), as compared with cultures exposed to fetal calf serum (FCS). Immunoprecipitation and western blot analysis of the EGF receptor (EGFR) revealed a significant reduction of its EGF‐induced tyrosine phosphorylation in cells treated with the NO donor 2‐(N,N‐diethylamino)‐diazenolate‐2‐oxide (DEA‐NO). When total cell lysates were subjected to western blotting, we observed that DEA‐NO also reduced tyrosine phosphorylation in EGF‐activated phosphoproteins, but not in those proteins whose tyrosine phosphorylation was evident in the absence of EGF. The effect of NO on EGFR transphosphorylation was concentration‐dependent and transient, with a total recovery observed between 1.5 and 3 h after addition of DEA‐NO to the cells. When cells were incubated for 15 min with DEA‐NO and then washed, the EGFR transphosphorylation returned to control levels immediately, indicating that the interaction of NO with the receptor molecule was fully reversible. NB69 cells expressed both the neuronal and the inducible isoforms of NO synthase (NOS) when cultured in the presence of FCS; under this condition, the NOS inhibitor, Nω‐nitro‐l‐arginine methyl ester, produced a small but significant increase in cell proliferation. The results suggest that NO is an endogenous antimitotic agent and that its interaction with EGFR contributes to cytostasis in NB69 cells.
Antibodies to L‐periaxin in sera of patients with peripheral neuropathy produce experimental sensory nerve conduction deficits
Authors: Lawlor Mike W. , Richards Michael P. , De Vries George H. , Fisher Morris A. , Stubbs Evan B.
Published: March 2003

L‐Periaxin is a PDZ‐domain protein localized to the plasma membrane of myelinating Schwann cells and plays a key role in the stabilization of mature myelin in peripheral nerves. Mutations in L‐periaxin have recently been described in some patients with demyelinating peripheral neuropathy, suggesting that disruption of L‐periaxin function may result in nerve injury. In this study, we report the presence of autoantibodies to L‐periaxin in sera from two of 12 patients with diabetes mellitus (type 2)‐associated neuropathy and three of 17 patients with IgG monoclonal gammopathy of undetermined significance (MGUS) neuropathy, an autoimmune peripheral nerve disorder. By comparison, anti‐L‐periaxin antibodies were not present in sera from nine patients with IgM MGUS neuropathy or in sera from 10 healthy control subjects. The effect of anti‐L‐periaxin serum antibody on peripheral nerve function was tested in vivo by intraneural injection. Sera containing anti‐L‐periaxin antibody, but not sera from age‐matched control subjects, injected into the endoneurium of rat sciatic nerve significantly (p < 0.005, n = 3) attenuated sensory‐evoked compound muscle action potential (CMAP) amplitudes in the absence of temporal dispersion. In contrast, motor‐evoked CMAP amplitudes and latencies were not affected by intraneural injection of sera containing anti‐L‐periaxin antibody. Light and electron microscopy of anti‐L‐periaxin serum‐injected nerves showed morphologic evidence of demyelination and axon enlargement. Depleting sera of anti‐L‐periaxin antibodies neutralized the serum‐mediated effects on nerve function and nerve morphology. Together, these data support anti‐L‐periaxin antibody as the pathologic agent in these serum samples. We suggest that anti‐L‐periaxin antibodies, when present in sera of patients with IgG MGUS‐ or diabetes‐associated peripheral neuropathy, may elicit sensory nerve conduction deficits.
Altered processing of amyloid precursor protein in the human neuroblastoma SH‐SY5Y by chronic hypoxia
Authors: Webster Nicola J. , Green Kim N. , Peers Chris , Vaughan Peter F. T.
Published: March 2003

Alzheimer's disease (AD) is more prevalent following an ischemic or hypoxic episode, such as stroke. Indeed, brain levels of amyloid precursor protein (APP) and the cytotoxic amyloid β peptide (Aβ) fragment are enhanced in these patients and in animal models following experimental ischaemia. We have investigated the effect of chronic hypoxia (CH; 2.5% O2, 24 h) on processing of APP in the human neuroblastoma, SH‐SY5Y. We demonstrate that constitutive and muscarinic‐receptor‐enhanced secretion of the α‐secretase cleaved fragment of APP, sAPPα, was reduced by ∼60% in CH cells. The caspase inhibitor BOC‐D(Ome)FMK did not reverse this effect of CH, and CH cells were as viable as controls, based on MTT assays. Thus, loss of sAPPα is not related to cell death or caspase processing of APP. Pre‐incubation with antioxidants did not reverse the effect of CH, and the effect could not be mimicked by H2O2, discounting the involvement of reactive oxygen species in hypoxic loss of sAPPα. CH did not affect muscarinic activation of extracellular‐signal regulated kinase. However, expression of ADAM 10 (widely believed to be α‐secretase) was decreased approximately 50% following CH. Thus, CH selectively decreases processing of APP by the α‐secretase pathway, most likely by decreasing levels of ADAM 10.
Induction of COX‐2 and reactive gliosis by P2Y receptors in rat cortical astrocytes is dependent on ERK1/2 but independent of calcium signalling
Authors: Brambilla Roberta , Neary Joseph T. , Cattabeni Flaminio , Cottini Lorenzo , D'Ippolito Gianluca , Schiller Paul C. , Abbracchio Maria P.
Published: March 2003

The present study has been aimed at characterizing the ATP/P2 receptor (and transductional pathways) responsible for the morphological changes induced in vitro by αβmethyleneATP on rat astrocytes obtained from cerebral cortex, a brain area highly involved in neurodegenerative diseases. Exposure of cells to this purine analogue resulted in elongation of cellular processes, an event reproducing in vitro a major hallmark of in vivo reactive gliosis. αβmethyleneATP‐induced gliosis was prevented by the P2X/P2Y blocker pyridoxalphosphate‐6‐azophenyl‐2′‐4′‐disulfonic acid, but not by the selective P2X antagonist 2′,3′‐O‐(2,4,6‐trinitrophenyl)‐ATP, ruling out a role for ligand‐gated P2X receptors. Conversely, the Gi/Go protein inactivator pertussis toxin completely prevented αβmethyleneATP‐induced effects. No effects were induced by αβmethyleneATP on intracellular calcium concentrations. RT‐PCR and western blot analysis showed that αβmethyleneATP–induced gliosis involves up‐regulation of cyclooxygenase‐2 (but not lipooxygenase). Also this effect was fully prevented by pyridoxalphosphate‐6‐azophenyl‐2′‐4′‐disulfonic acid. Experiments with inhibitors of mitogen‐activated protein kinases (MAPK) suggest that extracellular signal regulated protein kinases (ERK)1/2 mediate both cyclooxygenase‐2 induction and the associated in vitro gliosis. These findings suggest that purine‐induced gliosis involves the activation of a calcium‐independent G‐protein‐coupled P2Y receptor linked to ERK1/2 and cyclooxygenase‐2. Based on the involvement of cyclooxygenase‐2 and inflammation in neurodegenerative diseases, these findings open up new avenues in the identification of novel biological targets for the pharmacological manipulation of neurodegeneration.
Regional differences in processing of locally translated prohormone in peptidergic neurons of Aplysia californica
Authors: Lee Wenjau , Jones Andrea M. , Ono Joyce K. , Wayne Nancy L.
Published: March 2003

Earlier work showed that cell bodies and neurites of the peptidergic bag cell neurons of Aplysia californica contain mRNA for egg‐laying hormone. The purpose of the present study was to determine if egg‐laying hormone synthesis and prohormone processing is similar in the pleurovisceral connective nerves (containing neurites of bag cell neurons) and the bag cell neuron clusters (containing both cell bodies and neurites of bag cell neurons). Initial experiments confirmed by RT‐PCR and sequencing that egg‐laying hormone mRNA was present in the pleurovisceral connective nerves. To investigate possible regional differences in translation of mRNA and prohormone processing, clusters were separated from connective nerves and newly synthesized egg‐laying hormone‐immunoreactive proteins were analyzed. Results showed that synthesis and processing of prohormone occurred in both the clusters and isolated connective nerves; however, the relative abundance of prohormone, processing intermediates, and egg‐laying hormone was different. Pulse‐chase experiments showed that prohormone was processed more slowly in the connective nerves than in the clusters. These results show that mRNA in isolated neural processes of neuroendocrine cells can be translated, and that the cellular machinery for protein synthesis is present, but processing of the ELH prohormone is significantly compromised.
Correlation of local changes in extracellular oxygen and pH that accompany dopaminergic terminal activity in the rat caudate–putamen
Authors: Venton B. Jill , Michael Darren J. , Wightman R. Mark
Published: March 2003

Terminal activity causes an increase in local cerebral blood flow that can be quantified by measuring the accompanying increase in tissue oxygen. Alkaline pH changes can also follow neuronal activation. The purpose of these studies was to determine whether these changes in extracellular oxygen and pH correlate. Fast‐scan cyclic voltammetry was used to detect changes in dopamine, pH and oxygen levels simultaneously in the caudate–putamen after electrical stimulation of the substantia nigra in anesthetized rats. The biphasic increases in oxygen and pH followed similar time courses, and were delayed a few seconds from the immediate release and uptake of dopamine. The changes following administration of neurotransmitter receptor antagonists as well as agents that modulate blood flow were identical for oxygen and pH. Two distinct mechanisms were identified that give rise to the oxygen and pH changes: blood vessel dilatation caused by nitric oxide synthesis after muscarinic receptor activation and adenosine receptor activation. We conclude that changes in blood flow accompanying terminal activity cause alkaline pH shifts by the rapid removal of carbon dioxide, a component of the extracellular brain buffering system.
Tethering the N‐terminus of the prion protein compromises the cellular response to oxidative stress
Authors: Zeng Fanning , Watt Nicole T. , Walmsley Adrian R. , Hooper Nigel M.
Published: March 2003

The role of the N‐terminal half of the prion protein (PrPC) in normal cellular function and pathology remains enigmatic. To investigate the biological role of the N‐terminus of PrP, we examined the cellular properties of a construct of murine PrP, PrP‐DA, in which the N‐terminus is tethered to the membrane by an uncleaved signal peptide and which retains the glycosyl‐phosphatidylinositol anchor. Human neuroblastoma SH‐SY5Y cells expressing PrP‐DA were more susceptible to hydrogen peroxide and copper induced toxicity than wtPrP expressing cells. The PrP‐DA expressing cells had an increased level of intracellular free radicals and reduced levels of superoxide dismutase and glutathione peroxidase as compared to the wtPrP expressing cells. The membrane topology, cell surface location, lipid raft localisation, intracellular trafficking and copper‐mediated endocytosis of PrP‐DA were not significantly different from wtPrP. However, cells expressing PrP‐DA accumulated an N‐terminal fragment that was resistant to proteinase K. The data presented here are consistent with the N‐terminal region of PrPC having a role in the cellular response to oxidative stress, and that tethering this region of the protein to the membrane compromises this function through the accumulation of a protease‐resistant N‐terminal fragment, similar to that seen in some forms of human prion disease.
The role of phosphatidylinositol 3‐kinase in neural cell adhesion molecule‐mediated neuronal differentiation and survival
Authors: Ditlevsen Dorte K. , Køhler Lene B. , Pedersen Martin V. , Risell Michael , Kolkova Kateryna , Meyer Morten , Berezin Vladimir , Bock Elisabeth
Published: March 2003

The neural cell adhesion molecule, NCAM, is known to stimulate neurite outgrowth from primary neurones and PC12 cells presumably through signalling pathways involving the fibroblast growth factor receptor (FGFR), protein kinase A (PKA), protein kinase C (PKC), the Ras‐mitogen activated protein kinase (MAPK) pathway and an increase in intracellular Ca2+ levels. Stimulation of neurones with the synthetic NCAM‐ligand, C3, induces neurite outgrowth through signalling pathways similar to the pathways activated through physiological, homophilic NCAM‐stimulation. We present here data indicating that phosphatidylinositol 3‐kinase (PI3K) is required for NCAM‐mediated neurite outgrowth from PC12‐E2 cells and from cerebellar and dopaminergic neurones in primary culture, and that the thr/ser kinase Akt/protein kinase B (PKB) is phosphorylated downstream of PI3K after stimulation with C3. Moreover, we present data indicating a survival‐promoting effect of NCAM‐stimulation by C3 on cerebellar and dopaminergic neurones induced to undergo apoptosis. This protective effect of C3 included an inhibition of both DNA‐fragmentation and caspase‐3 activation. The survival‐promoting effect of NCAM‐stimulation was also shown to be dependent on PI3K.
Cholesterol is necessary both for the toxic effect of Aβ peptides on vascular smooth muscle cells and for Aβ binding to vascular smooth muscle cell membranes
Authors: Subasinghe Supundi , Unabia Sharon , Barrow Colin J. , Mok Su San , Aguilar Marie‐Isabel , Small David H.
Published: March 2003

Accumulation of beta amyloid (Aβ) in the brain is central to the pathogenesis of Alzheimer's disease. Aβ can bind to membrane lipids and this binding may have detrimental effects on cell function. In this study, surface plasmon resonance technology was used to study Aβ binding to membranes. Aβ peptides bound to synthetic lipid mixtures and to an intact plasma membrane preparation isolated from vascular smooth muscle cells. Aβ peptides were also toxic to vascular smooth muscle cells. There was a good correlation between the toxic effect of Aβ peptides and their membrane binding. ‘Ageing’ the Aβ peptides by incubation for 5 days increased the proportion of oligomeric species, and also increased toxicity and the amount of binding to lipids. The toxicities of various Aβ analogs correlated with their lipid binding. Significantly, binding was influenced by the concentration of cholesterol in the lipid mixture. Reduction of cholesterol in vascular smooth muscle cells not only reduced the binding of Aβ to purified plasma membrane preparations but also reduced Aβ toxicity. The results support the view that Aβ toxicity is a direct consequence of binding to lipids in the membrane. Reduction of membrane cholesterol using cholesterol‐lowering drugs may be of therapeutic benefit because it reduces Aβ‐membrane binding.
Effects of phosphatidylserine on p38 mitogen activated protein kinase, cyclic AMP responding element binding protein and nuclear factor‐κB activation in resting and activated microglial cells
Authors: Ajmone‐Cat M. A. , De Simone R. , Nicolini A. , Minghetti L.
Published: March 2003

In the last few years, the interaction between phosphatidylserine (PS), a phospholipid that becomes permanently exposed on the external cell surface in the early phases of apoptosis, and its specific receptor (PtdSerR) has emerged as a crucial event for the engulfing of apoptotic cells and for preventing the acquisition of pro‐inflammatory functions by peripheral macrophages. Recently, we demonstrated that PtdSerR is expressed in microglial cultures purified from neonatal rat brain, and that PS‐liposomes, used to mimic apoptotic cells, strongly reduce the lipopolysaccharide (LPS)‐induced release of inflammatory mediators. Here, we show that in resting microglia, PS‐liposomes induce cyclic AMP responding element binding protein (CREB) phosphorylation but do not activate nuclear factor‐κB (NF‐κB) and p38 mitogen‐activated protein kinase (p38), in line with the non‐inflammatory consequences of the recognition and removal of apoptotic cells by macrophages. In LPS‐activated microglia, PS‐liposomes did not affect NF‐κB activation but inhibited the phosphorylation of p38 and delayed that of CREB. To our knowledge, this is the first biochemical evidence of the molecular signaling evoked by PS/PtdSerR interaction possibly related to repression of pro‐inflammatory activities in microglial cells.
Expanding the association between the APOE gene and the risk of Alzheimer's disease: possible roles for APOE promoter polymorphisms and alterations in APOE transcription
Authors: Laws Simon M. , Hone Eugene , Gandy Sam , Martins Ralph N.
Published: March 2003

Alzheimer's disease (AD) is the most commonly diagnosed form of dementia in the elderly. Predominantly this disease is sporadic in nature with only a small percentage of patients exhibiting a familial trait. Early‐onset AD may be explained by single gene defects; however, most AD cases are late onset (> 65 years) and, although there is no known definite cause for this form of the disease, there are several known risk factors. Of these, the ε4 allele of the apolipoprotein E (apoE) gene (APOE) is a major risk factor. The ε4 allele of APOE is one of three (ɛ2 ɛ3 and ɛ4) common alleles generated by cysteine/arginine substitutions at two polymorphic sites. The possession of the ɛ4 allele is recognized as the most common identifiable genetic risk factor for late‐onset AD across most populations. Unlike the pathogenic mutations in the amyloid precursor or those in the presenilins, APOEɛ4 alleles increase the risk for AD but do not guarantee disease, even when present in homozygosity. In addition to the cysteine/arginine polymorphisms at the ɛ2/ɛ3/ɛ4 locus, polymorphisms within the proximal promoter of the APOE gene may lead to increased apoE levels by altering transcription of the APOE gene. Here we review the genetic and biochemical evidence supporting the hypothesis that regulation of apoE protein levels may contribute to the risk of AD, distinct from the well known polymorphisms at the ɛ2/ɛ3/ɛ4 locus.
Activation of mitochondrial ATP‐sensitive potassium channels increases cell viability against rotenone‐induced cell death
Authors: Tai Kwok‐Keung , McCrossan Zoe A. , Abbott Geoffrey W.
Published: March 2003

We recently showed that activation of ATP‐sensitive potassium (KATP) channels in PC12 cells induces protection against the neurotoxic effect of rotenone, a mitochondrial complex I inhibitor. In this study, we sought to determine the locus of the KATP channels that mediate this protection in PC12 cells. We found that pretreatment of PC12 cells with diazoxide, a mitochondrial KATP channel selective opener, dose‐dependently increases cell viability against rotenone‐induced cell death as indicated in trypan blue exclusion assays. The protective effect of this preconditioning is attenuated by 5‐hydroxydecanoic acid (5‐HD), a selective mitochondrial KATP channel antagonist but not in the presence of HMR‐1098, a selective plasma membrane KATP potassium channel antagonist. In contrast, P‐1075, a selective plasma membrane KATP channel opener, does not induce protection. Using specific antibodies against SUR1 and Kir6.1, we detected immunoreactive proteins of apparent molecular masses 155 and 50 kDa, corresponding to those previously reported for SUR1 and Kir6.1, respectively, in the mitochondria‐enriched fraction of PC12 cells. In addition, whole cell patch‐clamp studies revealed that inward currents in PC12 cells are insensitive to P‐1075, HMR‐1098, glibenclamide and diazoxide, indicating that functional plasma membrane KATP channels are negligible. Taken together, our results demonstrate for the first time that activation of mitochondrial KATP channels elicits protection against rotenone‐induced cell death.
Swedish general practitioners’ awareness of elderly patients at risk of or actually suffering from elder abuse
Authors: Saveman Britt‐Inger , Sandvide Åsa
Published: March 2003

Swedish general practitioners’ awareness of elderly patients at risk of or actually suffering from elder abuse

The aim of this study was to describe the awareness among Swedish general practitioners (GPs) of elderly patients at risk of or suffering from abuse during a 12‐month period. A questionnaire was sent to 110 GPs working in one regional health care district in Sweden, and 59% answered and returned the questionnaire. Seventy‐seven per cent of the GPs reported having one patient at risk of abuse and or neglect, and 25% were aware of patients who were subjected to verified or suspected elder abuse. Risk situations commonly involved patients with dementia, carers with problems of their own or who felt angry about the burden of caring, or paid carers who were unable to meet the needs of the elderly person. There were GPs who had contact with colleagues, district nurses and others, as well as those who had few or no contacts at all. It is important to take seriously the large number of GPs who have elderly patients in situations where there is a risk of abuse or neglect. If elder abuse is not primarily a medical problem – it is essential that there should be a clearly identified authority to which GPs can refer cases.
Breast cancer and experiences of social support
Authors: Landmark B. T. , Strandmark M. , Wahl A.
Published: March 2003

Breast cancer and experiences of social support. In‐depth interviews of 10 women with newly diagnosed breast cancer

The present study aimed to describe how 10 Norwegian women with newly diagnosed breast cancer experienced living with the disease. A qualitative method based on principles in Grounded Theory was used. Data were collected through in‐depth interviews. This paper explores the experience of social support as it evolves in women's relationships with others. Social support contains emotional, practical and informative dimensions. Here relationships are called interactions. Interaction can be divided into two groups. Interactions with close relatives and others the women know and have contact with. Interactions with organizations and institution staff. These interactions consist of social support and lack of social support. Health professionals can assist women and their families in this life‐threatening situation, by increasing their awareness of social support issues.
A theoretical extension of the concept of energy through an empirical study
Authors: Lerdal Anners
Published: March 2003

A theoretical extension of the concept of energy through an empirical study

This paper extends the concept of energy as a multifaceted concept of the experience of energy and proposes a theoretical model regarding the understanding of the experience of energy. The hybrid model of concept development (Schwartz‐Barcott and Kim, 2000) was used in a qualitative empirical study with a sample of athletes and chronically ill individuals. The concept of energy presented is a global concept and can be placed within the much‐discussed concept of fatigue. Focusing on energy implicates a resource approach to individuals experiencing fatigue. A theoretical model for the experience of energy emerging from this study includes the subconcepts of the feeling of energy, perceived energy capacity, energy management, and performance of activities. Two sets of strategies within the concept of energy management are identified as energy economizing and energy generating. This article explores the potential of the concept of energy in describing fatigue as a health problem. Implications for clinical practice and further theoretical development are suggested.
Patient satisfaction with nursing care in the context of health care: a literature study
Authors: Johansson Peter , Oléni Magnus , Fridlund Bengt
Published: March 2003

To evaluate and improve the quality of care provided, it is of vital importance to investigate the quality of care in the context of health care. Patient satisfaction is a significant indicator of the quality of care. Consequently, quality work includes investigations that map out patient satisfaction with nursing care. To improve the quality of nursing care, the nurse needs to know what factors influence patient satisfaction. The aim of this literature study was to describe the influences on patient satisfaction with regard to nursing care in the context of health care. In the description of nursing care, we have used Henderson's nursing care model. The results describe eight domains that have an influence on patient satisfaction with nursing care: the socio‐demographic background of the patients, patients' expectations regarding nursing care, the physical environment, communication and information, participation and involvement, interpersonal relations between nurse and patient, nurses' medical–technical competence, and the influence of the health care organization on both patients and nurses. The bulk of the literature included in the study came from the UK, Sweden and the USA. This means that the results should be applicable to health care in the western world. An important implication for future research is to continue to elucidate the factors that influence satisfaction with nursing care, as seen from the patient's perspective.
Coping with illness‐related problems in persons with progressive muscular diseases: the Swedish version of the Ways of Coping Questionnaire
Authors: Ahlström Gerd , Wenneberg Stig
Published: March 2003

One of the most widely used self‐assessment inventories of coping is the Ways of Coping Questionnaire. The aims of the study were to describe coping with illness‐related problems in persons with muscular diseases and to investigate the influence of demographic variables. Also, the reliability of the Swedish version of the Ways of Coping Questionnaire was to be evaluated. Forty‐four persons with muscular dystrophy and 32 persons with postpolio syndrome, along with a comparison group of 214 students, completed the questionnaire. The findings of this study show that there are some different coping patterns in students as compared with persons with chronic disease. The coping strategy Distancing was used more and the strategy Accepting Responsibility used less frequently in the chronic disease groups and may be an expression of the inevitable physical limitations caused by the progressiveness of muscular dystrophy and postpolio syndrome. Furthermore, persons with muscular dystrophy also used less problem‐focused coping in the form of Confrontive Coping and Planful Problem Solving when compared with the postpolio and student groups. In addition, women in the three groups employed the strategy of Seeking Social Support more often than did men. Regarding the psychometric properties of the Swedish version of the Ways of Coping Questionnaire, internal consistency was acceptable for the total score, but lower and not acceptable for several of the subscales. In the student group, but not in the chronic disease groups, there were low correlations between subscales, which indicate discriminative ability. More research is necessary to further investigate the reliability and validity of the Swedish version of the Ways of Coping Questionnaire before this instrument can be used routinely to assess coping patterns in patients with chronic disease.
Characterization of microsatellite loci in chinook salmon (Oncorhynchus tshawytscha) and cross‐species amplification in other salmonids
Authors: Williamson Kevin S. , Cordes Jan F. , May Bernie
Published: March 2003

Previous studies of population genetic structure of fall‐run chinook salmon (Oncorhynchus tshawytscha) in California’s Central Valley have either not focused on or have been unable to resolve intertributary differences within the San Joaquin River basin. The authors describe the isolation, the polymerase chain reaction conditions, and characterize the cross‐species amplification of 17 microsatellite loci in six species of salmonids. Fourteen of these loci are polymorphic in fall‐run chinook from the San Joaquin River drainage. These results indicate the potential utility of microsatellite markers developed for one species, for both congenerics and species within a closely related genus.
Characterization of 22 microsatellites loci from the endangered Houbara bustard (Chlamydotis undulata undulata)
Authors: Chbel Faiza , Broderick Damien , Idaghdour Youssef , Korrida Amal , Mccormick Paul
Published: March 2003

Here we present a new set of 22 microsatellite loci isolated from Chlamydotis undulata undulata, an endangered Houbara bustard found across North Africa. The number of alleles per locus ranged from one to nine, and heterozygosities ranged from 0.167 to 0.944. Total exclusionary probabilities using these loci for the first and the second parent were 0.992932 and 0.999915, respectively. Successful cross‐amplification was observed in eight other Otididae species (12–22 of the 22 loci). These microsatellite markers are powerful tools for genetic identification, paternity assignment and population genetic studies.
Characterization of 16 microsatellite marker loci in the Maasai giraffe (Giraffa camelopardalis tippelskirchi)
Authors: Huebinger Ryan M. , Pierson Donna J. , De Maar Thomas W. , Brown David M. , Brenneman Rick A. , Louis Edward E.
Published: March 2003

Sixteen polymorphic microsatellite markers with an average allele size of k = 4.3 are identified from a genomic plasmid library constructed for giraffe (Giraffa camelopardalis ssp.). Primer sequences and marker data are reported in tabular form. The markers were screened in a population of 25 Maasai giraffe (G. c. tippelskirchi) collected near the Athi River, Kenya. The average observed heterozygosity for each marker was 0.36 with an average expected heterozygosity of 0.535. Hardy–Weinberg deviations are reported from this population, which is suspected to be inbred. The markers will be used to screen the captive giraffe population for subspecific or hybrid classification.
Isolation and characterization of microsatellite loci from a threatened rattlesnake (New Mexico Ridge‐nosed Rattlesnake, Crotalus willardi obscurus)
Authors: Holycross A. T. , Douglas M. E. , Higbee J. R. , Bogden R. H.
Published: March 2003

Six novel microsatellite loci are identified from genomic DNA of the threatened New Mexico Ridge‐nosed Rattlesnake (Crotalus willardi obscurus). Data from the Animas Mountains (New Mexico) population demonstrate these loci: (i) are highly variable with 5–24 alleles per locus, expected heterozygosities between 0.35 and 0.92, and observed heterozygosities between 0.32 and 0.91; (ii) are sufficiently variable for assigning parentage with total exclusionary power for the first parent of 0.96, and 0.99 for the second parent; and (iii) amplify similar size fragments in other rattlesnakes (C. atrox, C. lutosus, C. scutulatus, and C. tigris).
Isolation of microsatellite loci in the Florida Scrub‐Jay Aphelocoma coerulescens
Authors: Stenzler L. M. , Fitzpatrick J. W.
Published: March 2003

The Florida Scrub‐Jay (Aphelocoma coerulescens), a habitat specialist listed as Threatened by the U.S. Fish and Wildlife Service, exhibits extremely limited natal dispersal. We hypothesize that this behaviour results in a correlation of genetic and geographical distance. To test this, we are sampling intensively along the north–south orientated Lake Wales Ridge of central Florida. We describe the isolation and characterization of 31 microsatellite loci developed to determine the minimum distance at which genetic structure can be detected, and to test for isolation by distance. There are 3–15 alleles per locus, with expected heterozygosities from 0.16 to 0.86.
Isolation of polymorphic microsatellites in the stemless thistle (Cirsium acaule) and their utility in other Cirsium species
Authors: Jump Alistair S. , Dawson Deborah A. , James Celia M. , Woodward F. Ian. , Burke Terry
Published: March 2003

The genus Cirsium includes species with both widespread and restricted geographical distributions, several of which are serious weeds. Nine polymorphic microsatellite loci were isolated from the stemless thistle Cirsium acaule. Eight were polymorphic in C. acaule, six in C. arvense and seven in C. heterophyllum. One locus monomorphic in C. acaule showed polymorphism in C. heterophyllum. The mean number of alleles per locus was 4.1 in C. acaule, 6.2 in C. arvense and 2.9 in C. heterophyllum. These nine loci were also amplified in C. eriophorum and C. vulgare, suggesting that these markers may be of use throughout the genus.
Ecological differentiation in relation to bill size amongst sympatric, genetically undifferentiated crossbills Loxia spp.
Authors: Marquiss Mick , Rae Robert
Published: March 2003

Recent evidence of genetic homogeneity across morphologically diverse crossbill taxa Loxia spp. suggests that strong directional natural selection sustains morphological differences. If so, we would expect that, in sympatry, persistent crossbill morphs will be associated with the ecological circumstances that select for particular features. Here we report on a field study of niche differentiation in sympatric crossbills, showing correlation between bill size and habitat use, foraging and movements. In Deeside, north‐east Scotland, crossbills occupied three ecological niches. Small‐billed birds L. curvirostra were itinerant and migratory. They switched between conifer species in relation to the phenology of cone ripeness, feeding on spruce or larch from summer through winter and Scots Pine Pinus sylvestris in spring and early summer. Large‐billed birds L. pytyopsittacus were more sedentary, feeding on pine seed year round in semi‐natural pine forest. Birds with intermediate bills L. scotica were also sedentary but switched seasonally between conifer species. Deeside crossbills thus occupied three niches in line with the current designation of three species, but in the study years (1990–1997) there was no shortage of conifer seed and no evidence of strong selection for optimal bill size. Bill sizes did not fall precisely into three distinct modes so other factors were involved. These could have included the immigration of two sizes of L. curvirostra, and introgression (and possibly phenotypic plasticity) amongst the more sedentary larger‐billed birds. The origin of L. scotica is discussed within the context of novel habitat, introgression, niche shift and competition for pine seed.
The effect of nest ectoparasites on parental provisioning in a north‐African population of the Blue TitParus caeruleus
Authors: Bouslama Zihad , Lambrechts Marcel M. , Ziane Nadia , Djenidi Rédha , Chabi Yassine
Published: March 2003

Bird nests are often heavily infested with several haematophagous ectoparasite species that drain energy and other essential resources needed for the development of the rapidly growing chicks. The nutritional requirements of altricial chicks can only be satisfied by the parents frequently bringing prey to the nest. In a 3‐year study, we tested experimentally whether a parasite‐induced change in the nutritional budgets of the chicks in an Algerian population of the Blue Tit, could be compensated by a response in parental food provisioning behaviour. We found that nestling body mass and size did not differ between heat‐treated ‘parasite‐free’ nests and heavily infested control nests. However, after controlling for potential confounding variables (laydate, clutch size, chick age, year), we found that broods of heavily infested control nests were more frequently visited and fed than broods that received antiparasite treatment. The results are discussed in the framework of theory related to behavioural responses of hosts to parasites.
Brood parasitism and egg matching in the Red‐chested Cuckoo Cuculus solitarius in southern Africa
Authors: Kuiper S. M. , Cherry M. I.
Published: March 2003

Host usage and relative rates of egg matching were investigated in the Red‐chested Cuckoo Cuculus solitarius in southern Africa, using nest record cards and museum collections. Eighteen host species were found to be parasitized at varying degrees of intensity (0.14–12.5%). The most commonly recorded parasitized host, the Cape Robin Cossypha caffra, had a relatively low rate of parasitism (2.46%). The host species experiencing the most recorded pressure from parasitism was the Bearded Robin Erythropygia quadrivirgata, with 12.5% parasitism. Human perception of cuckoo/host egg matching was assessed for parasitized clutches of host species in museum egg collections. Eggs of three different cuckoo egg morphs were scored as matching those of the host species on a 1–5 scale. Perfect/good matching was recorded for eggs found in Chorister Cossypha dichroa, Heuglin's Cossypha heuglini and Natal Robins’Cossypha natalensis clutches. Poor and very poor matching was evident for cuckoo eggs found in four host species’ clutches: the Cape Robin, Stonechat Saxicola torquata, Cape Rockthrush Monticola rupestris and Black Flycatcher Melaenornis pammelaina. Available evidence suggests that the Red‐chested Cuckoo parasitizes hosts in a particular environment (low vegetation and trees). Good to intermediate matching was recorded with only 47% of host eggs, and with only 28.5% of Cape Robin clutches. A relatively high degree of host specificity, however, is suggested by the nest record card data, which indicate that species with large numbers of records are not those with the highest rates of parasitism.
The significance of ultraviolet radiation for eye diseases. A review with comments on the efficacy of UV‐blocking contact lenses
Authors: Bergmanson J. P. G. , Söderberg P. G.
Published: March 2003

Acute and cumulative ultraviolet radiation (UVR) exposure has been proposed as an important causative factor in the development of a whole spectrum of eye diseases. The present review examines the scientific evidence for and against such an association, with special emphasis on recent additions to the literature. The sun is the main UVR source on earth, and it is beyond scientific doubt that the cornea can be harmed by both acute and cumulative ambient exposures. There is also powerful epidemiological support for an association between chronic UVR exposure and the formation of cataracts and pterygia. The evidence in support of UVR linkage to pinguecula, ocular neoplasms and retinal changes is weaker‐in part because there are fewer studies reported in the literature. It is concluded that UVR‐blocking hydrogel contact lenses and spectacles are two equally effective preventive measures in minimizing unnecessary suffering and health costs, especially for people who spend a significant time outdoors and for those who live in more UV intense environments. UVR‐blocking contact lenses and spectacles must not, however, be substitutes in situations that require UVR‐blocking safety goggles.
Contrast sensitivity after wearing prisms to correct for heterophoria
Authors: Methling Dieter , Jaschinski Wolfgang
Published: March 2003

Contrast sensitivity to sinusoidal gratings was measured at spatial frequencies of 1.5–16 c/deg in 8 subjects before and after wearing prisms (for at least two weeks) to correct heterophoria, prescribed by the full correction method of H.‐J. Haase (Binocular testing and distance correction with the Berlin Polatest [trans. W. Baldwin]. J. Am. Optom. Assoc. 34, 115–125, 1962). At higher spatial frequencies of 12–16 c/deg, we found an average improvement in contrast sensitivity of 0.15 log unit. This effect is estimated to correspond to an increase in visual acuity of 15%.
Microfluctuations of steady‐state accommodation measured with ultrasonography
Authors: van der Heijde G. L. , Beers A. P. A. , Dubbelman M.
Published: March 2003

Over the past 30 years investigators have noted fluctuations in accommodation when the eye views a stationary target. These microfluctuations have been studied mainly with the use of infrared optometers. Two dominant components have been found: a low frequency component (LFC; 0.05–0.5 Hz) and a high frequency component (HFC; 1.0–2.2 Hz). The LFC probably has a neurological origin. The HFC is supposed to be related to the arterial pulse. The aim of this study was to investigate accommodative fluctuations and gain more information about their origin by using a non‐optical method. We used continuous ultrasonographic biometry to measure changes in anterior chamber (AC) depth, lens thickness and vitreous length during steady‐state accommodation. Simultaneously, the electrocardiogram (ECG) was recorded. Changes in axial length were calculated offline by taking the sum of the changes in the three intraocular distances. Results show that fluctuations with an LFC were present in all three intraocular distances but not in the axial length, proving that only the lens was involved. In contrast with the findings of investigators using optical methods, no HFC was present in fluctuations of AC depth and lens thickness. However, a small HFC was found in registrations of the vitreous and axial length, which appeared to correspond with the heart rate.
Visibility of motion in infant vernier displays, using adult subjects
Authors: Carkeet A. , Levi D. M. , Manny R. E.
Published: March 2003

Motion is frequently incorporated in stimuli used for psychophysical testing of vernier acuity in infants and young children. In such stimuli, detection of the vernier offset is necessary in order to perceive the motion. Research described in this report tested whether the perception of a vernier offset is sufficient to signal the stimulus motion in adults. We measured how motion detectability changed as a function of vernier offset for two adult subjects, using a stimulus similar to that employed by other authors to measure vernier acuity in infants and children. Motion visibility varied with offset size, achieving a detectability of motion (d′) of 0.95 (comparable to two‐alternative forced‐choice thresholds) at stimulus offsets of 16–19 s arc. In comparison to the motion, the stimulus offset itself was much easier to see, being detectable on 95–100% of trials with the smallest offset, 6.6 s arc. This distinction, between the visibility of motion and the visibility of the vernier offset itself, should be considered when interpreting vernier results using such displays, especially in infants and children for whom motion may be the attractive cue.
Calibration and validity of an eccentric photorefractor
Authors: Chan Osbert Y. C. , Edwards Marion , Brown Brian
Published: March 2003

A new graphical calibration method was developed to convert the photorefractive reflex into refractive error. With this graphical method, the refractive error can be obtained for pupil sizes and for photorefractive reflex sizes which have not been precalibrated. In the conventional method, the refractive error associated with non‐precalibrated pupil and reflex sizes is obtained by interpolating between neighbouring precalibrated points. This introduces error because the relationship between refractive error and pupil and reflex size is not linear. Three hundred and sixty‐one children aged between 36 and 65 months were clinically examined and photorefracted. The refractive error obtained using retinoscopy and the eccentric photorefractor agreed well with each other, although the photorefractor tended to under‐estimate refractive error. Using the referral criteria developed by Chan, O. Y. C. and Edwards, L. M. (Refraction referral criteria for Hong Kong Chinese Children. Ophthal. Physiol. Opt. 14, 259–256, 1994), the photorefractor had a sensitivity of 74.6% and a specificity of 96.4%. All the under‐referred cases were borderline, having just failed the referral criteria. All the cases with hyperopia of > + 2.0 D, astigmatism of > 1.25 D and visual acuity of worse than 6/18 were identified.
Weber's law for position is incidental rather than fundamental
Authors: Latham Keziah , Whitaker David
Published: March 2003

Purpose: Weber's law for position states that the minimum discriminable change in separation between two objects is proportional to the separation itself. This study aimed to disentangle the individual effects of separation, eccentricity and spatial scale in determining Weber's law for position.

Methods: Spatial interval discrimination thresholds were measured for two Gabor patches at twice contrast detection threshold. The patches varied in spatial scale (blur parameter of the patch), eccentricity (using isoeccentric arcs of different radii), and separation (varied by moving the patches around the isoeccentric arc). The effect of contrast on thresholds was also examined.

Results: Weber's law holds for geometrically similar stimuli, i.e. stimuli with a constant separation/eccentricity ratio, over a range of spatial scales and eccentricities. Thresholds are contrast dependent at small geometric ratios, and contrast‐independent at large ratios. The Weber fraction is optimum (4%) for fovea‐centred stimuli, and is contrast dependent at smaller geometric ratios, becoming smaller at higher contrasts.

Conclusions: Weber's law is observed at large geometric ratios because thresholds are proportional to eccentricity. At small geometric ratios, thresholds show a greater dependence on separation which increases with increasing contrast. Weber's law arises not from a single fundamental process, but from both increasing separation and increasing eccentricity, regardless of spatial scale.
The relative sensitivity of visual acuity and small letter contrast sensitivity in early cataract
Authors: Elliot David B. , Situ Ping
Published: March 2003

Purpose: To investigate the effects of early cataract on spatial frequency dependent contrast sensitivity (CS) measurement and log MAR visual acuity (VA) assessment.

Methods: The relative sensitivity of two computer‐generated letter CS tests, 1/9.5 letter CS (1/9.5 LCS) (assessing low to medium spatial frequency CS) and 6/9.5 letter CS (6/9.5 LCS) (measuring high spatial frequencies), and a log MAR VA test were evaluated in 19 subjects with early cataract and 21 age‐matched controls.

Results: Results indicate that these three tests decline with increasing cataract formation. The greatest visual reduction and the highest test discriminative ability were found with the 6/9.5 LCS test (Az score of 0.441 versus 0.408 for VA) and the lowest with the 1/9.5 LCS test (Az score of 0.383). However, measurement variability was greatest for 6/9.5 LCS. After correcting for this variability, the 6/9.5 LCS test still proved slightly more sensitive to early cataract and cataractous change than the other two measurements.

Conclusion: The study suggests that 6/9.5 LCS or other size small letter CS tests are able to detect more subtle vision loss in cataract than visual acuity.