bluuebunny/crossref_metadata_2025 huggingface dataset:
Option pricing with a non‐zero lower bound on stock price
Authors: Dong Ming
Published: June 2005

Black, F. and Scholes, M. (1973) assume a geometric Brownian motion for stock prices and therefore a normal distribution for stock returns. In this article a simple alternative model to Black and Scholes (1973) is presented by assuming a non‐zero lower bound on stock prices. The proposed stock price dynamics simultaneously accommodate skewness and excess kurtosis in stock returns. The feasibility of the proposed model is assessed by simulation and maximum likelihood estimation of the return probability density. The proposed model is easily applicable to existing option pricing models and may provide improved precision in option pricing. © 2005 Wiley Periodicals, Inc. Jrl Fut Mark 25:775–794, 2005
Survival of commodity trading advisors: 1990–2003
Authors: Gregoriou Greg N. , Hübner Georges , Papageorgiou Nicolas , Rouah Fabrice
Published: June 2005

This article investigates the mortality of Commodity Trading Advisors (CTAs) over the 1990–2003 period, a longer horizon than any encompassed in the literature. A detailed survival analysis over the full range of CTA classifications is provided, and it is found that the median lifetime of CTAs in this sample is different than previously documented. Through the implementation of nonparametric, parametric, and semiparametric statistical techniques, it is emphasized that CTA survivorship is heavily contingent on the strategy followed by the fund. Furthermore, a significant positive size effect on survival is shown, whereas poor returns, and to a lesser extent, high‐risk exposure, appear to hasten mortality. © 2005 Wiley Periodicals, Inc. Jrl Fut Mark 25:795–815, 2005
Is investor misreaction economically significant? Evidence from short‐ and long‐term S&P 500 index options
Authors: Cao Charles , Li Haitao , Yu Fan
Published: June 2005

Several recent studies present evidence of investor misreaction in the options market. Although the interpretation of their results is still controversial, the important question of economic significance has not been fully addressed. Here this gap is addressed by formulating regression‐based tests to identify misreaction and its duration and constructing trading strategies to exploit the empirical patterns of misreaction. Regular S&P 500 index options and long‐dated S&P 500 LEAPS are used to find an underreaction that on average dissipates over the course of 3 trading days and an increasing misreaction that peaks after four consecutive daily variance shocks of the same sign. Option trading strategies based on these findings produce economically significant abnormal returns in the range of 1–3% per day. However, they are not profitable in the presence of transaction costs. © 2005 Wiley Periodicals, Inc. Jrl Fut Mark 25:717–752, 2005
Chromosome 22 tiling‐path array–CGH analysis identifies germ‐line‐ and tumor‐specific aberrations in patients with glioblastoma multiforme
Authors: de Ståhl Teresita Díaz , Hartmann Christian , de Bustos Cecilia , Piotrowski Arkadiusz , Benetkiewicz Magdalena , Mantripragada Kiran K. , Tykwinski Tomasz , von Deimling Andreas , Dumanski Jan P.
Published: June 2005

Gliomas are common and frequently malignant tumors of the central nervous system. Recurrent allelic losses of chromosome 22 have been reported in gliomas, indicating tumor‐suppressor genes at this location. However, the target genes are still unknown. We applied a high resolution tiling‐path chromosome 22 array to a series of 50 glioblastoma samples, with the aim of investigating the underlying abnormalities in both constitutional and tumor‐derived DNA. We detected hemizygous deletions in 28% of the tumors (14 of 50), with monosomy 22 (10 of 50) being the predominant pattern. The distribution of overlapping hemizygous deletions delineated two putative tumor‐suppressor loci (11.1 and 3.08 Mb in size) across 22q. Most strikingly, we identified two distinct loci affected by regional gains. Both alterations were of germ‐line origin and were unique to samples from patients affected with tumors. Analysis of these two amplified regions revealed the presence of two interesting candidate genes: TOP3B and TAFA5. The TOP3B gene encodes a protein that seems to function in the unlinking of parental strands at the final stage of DNA replication and/or in the dissociation of structures in mitotic cells that could lead to recombination. The TAFA5 gene belongs to a novel family of proteins with similarity to chemokines and brain‐specific expression. The role of the identified candidate loci should be studied further. Our results demonstrated the power of array‐CGH to determine DNA copy number alterations in the context of germ‐line‐ and tumor‐specific aberrations. © 2005 Wiley‐Liss, Inc.
Nonrandom cell‐cycle timing of a somatic chromosomal translocation: The t(X;17) of alveolar soft‐part sarcoma occurs in G2
Authors: Huang Hsuan‐Ying , Lui Man Yee , Ladanyi Marc
Published: June 2005

The cell‐cycle timing of somatic chromosomal translocations in cancer remains poorly understood but may be relevant to their etiology and the mechanism of their formation. Alveolar soft‐part sarcoma (ASPS) is a rare malignant soft‐tissue tumor of uncertain lineage that provides an opportunity to address this question. The great majority of ASPSs have relatively simple near‐diploid karyotypes characterized by an unbalanced der(17)t(X;17)(p11.2;q25), resulting in nonreciprocal fusion of TFE3 with ASPSCR1 (a.k.a. ASPL), with consequent net gain of Xp11.2→pter and loss of 17q25→qter. The presence of a normal X along with the der(17)t(X;17) in ASPSs that occur in men has been well described in previous cytogenetic reports and is most readily explained by a translocation in the G2 phase of the cell cycle. To establish whether formation in G2 is a general feature of the t(X;17), we examined polymorphic loci in Xp11.2→qter in ASPS from 9 women, including 7 with an unbalanced t(X;17). Our analysis showed that all 7 displayed retention of heterozygosity at all informative markers on Xp11.2→qter, supporting preferential formation of the t(X;17) in the G2 phase of the cell cycle. Given that the two derivative chromosomes of a translocation in G2 would be expected to segregate together half the time, the predominance of an unbalanced der(17)t(X;17) also raises the possibility of a selective advantage in ASPS cells for gain of Xp11.2→pter or loss of 17q25.3→qter or retention of an active copy of TFE3. © 2005 Wiley‐Liss, Inc.
Auctions vs negotiations: a study of price differentials
Authors: Kjerstad Egil
Published: June 2005

Recent contributions in auction and bargaining theory suggest that a procurer should place more faith in the power of competition among alternative suppliers than in his or her own negotiating skill. Based on data from 216 contracts between procurers and suppliers of medical and surgical articles, we test whether auctions and bargaining result in significantly different prices. The main results are that auctions give ‘thicker’ markets compared with negotiations, as expected, but that auctions do not result in significantly lower prices compared with negotiations. Copyright © 2005 John Wiley & Sons, Ltd.
Methods for incorporating covariate adjustment, subgroup analysis and between‐centre differences into cost‐effectiveness evaluations
Authors: Nixon Richard M. , Thompson Simon G.
Published: June 2005

Background: Overall assessments of cost–effectiveness are now commonplace in informing medical policy decision making. It is often important, however, also to investigate how cost–effectiveness varies between patient subgroups. Yet such analyses are rarely undertaken, because appropriate methods have not been sufficiently developed.

Methods: We propose a coherent set of Bayesian methods to extend cost–effectiveness analyses to adjust for baseline covariates, to investigate differences between subgroups, and to allow for differences between centres in a multicentre study using a hierarchical model. These methods consider costs and effects jointly, and allow for the typically skewed distribution of cost data. The results are presented as inferences on the cost–effectiveness plane, and as cost–effectiveness acceptability curves.

Results: In applying these methods to a randomised trial of case management of psychotic patients, we show that overall cost–effectiveness can be affected by ignoring the skewness of cost data, but that it may be difficult to gain substantial precision by adjusting for baseline covariates. While analyses of overall cost–effectiveness can mask important subgroup differences, crude differences between centres may provide an unrealistic indication of the true differences between them.

Conclusions: The methods developed allow a flexible choice for the distributions used for cost data, and have a wide range of applicability – to both randomised trials and observational studies. Experience needs to be gained in applying these methods in practice, and using their results in decision making. Copyright © 2005 John Wiley & Sons, Ltd.
Regulation versus practice ‐ the impact of accessibility on the use of specialist health care in Norway
Authors: Iversen Tor , Kopperud Gry Stine
Published: June 2005

In Norway specialized health services are provided both by public hospitals and by privately practicing specialists who have a contract with the public sector. A patient's co‐payment is the same irrespective of the type of provider he visits. The ambition of equity in the allocation of medical care is high among all political parties. The instruments for auditing whether these goals are fulfilled are not equally ambitious. The objective of the present study is to explore whether laws and regulations that govern the allocation of specialist health care resources in fact are fulfilled. Panel data from the Survey of Living Conditions are merged with data on capacity and spatial access to primary and specialist care. We find that accessibility and socio‐economic variables play a considerable role in determining both the probability of at least one visit and the number of visits to a private specialist. A person with a higher university degree living in a municipality with the highest value of the geographical accessibility index has a 46%‐points higher probability of at least one visit to a private specialist compared with a person with junior high living in a municipality with the lowest value of the accessibility index. With regard to visits to a hospital outpatient department these variables are not found to have significant effects.

We conclude that public ambitions and regulations are fulfilled for specialist services provided by public hospitals. With regard to the provision of services provided by publicly financed private specialists we find a discrepancy between public goals and surveyed practice. Copyright © 2005 John Wiley & Sons, Ltd.
Socioeconomic status, depression disparities, and financial strain: what lies behind the income‐depression relationship?
Authors: Zimmerman Frederick J. , Katon Wayne
Published: June 2005

Prior studies have consistently found the incidence and persistence of depression to be higher among persons with low incomes, but causal mechanisms for this relationship are not well understood. This study uses the National Longitudinal Survey of Youth 1979 cohort to test several hypotheses about the robustness of the depression–income relationship among adults. In regressions of depression symptoms on income and sociodemographic variables, income is significantly associated with depression. However, when controls for other economic variables are included, the effect of income is considerably reduced, and generally not significant. Employment status and the ratio of debts‐to‐assets are both highly significant for men and for women both above and below the median income. Fixed‐effects estimates suggest that employment status and financial strain are causally related to depression, but income is not. Instrumental variable estimates suggest that financial strain may not lead to depression. Copyright © 2005 John Wiley & Sons, Ltd.
Towards protein folding with evolutionary techniques
Authors: Koskowski Florian , Hartke Bernd
Published: June 2005

We present design details and first tests of a new evolutionary algorithm approach to ab initio protein folding. It does not focus on dihedral angles exclusively, but mainly operates on introduction, extension, break‐up, and destruction of secondary structure elements, given as correlated dihedral angle values. In first test applications to polyalanines (up to 60 residues) and random primary sequences (up to 40 residues), we demonstrate that this use of prior knowledge is well balanced: On the one hand, it ensures quick introduction of secondary structure elements if they are favorable for a given primary sequence, but still allows for efficient location of pure random coil solutions without enforcing any secondary structure elements, if folds of this type are preferred by the given primary sequence. Furthermore, the algorithm is clearly able to pack several secondary structure elements into favorable tertiary structure arrangements, although no part of the algorithm is explicitly designed to do this. In first test examples on real‐life peptides between 21 and 44 residues from the Protein Data Bank, the quality of the results depends on the force field used (as expected); nevertheless, we can show that the algorithm is able to find structures in good agreement with the targets easily and consistently, if the force field allows for that. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 1169–1179, 2005
Why I (really) became a therapist
Authors: Ellis Albert
Published: June 2005

This article describes how the author really became a therapist and worked on his own social and performance anxiety. He was at first a follower of liberal psychoanalysis, but, in successfully using in vivo desensitization on himself, he overcame his anxiety and became highly constructivist. He finally created rational emotive behavior therapy, the pioneering cognitive‐behavior therapy; integrated it with emotional‐evocative and experiential methods; and used it to cope with much criticism he received about his active‐directive techniques. © 2005 Wiley Periodicals, Inc. J Clin Psychol/In Session 61: 945–948, 2005.
Don't be a sheep: How this eldest daughter became a feminist therapist
Authors: Brown Laura S.
Published: June 2005

This article describes what I consider to be important influences on the development of my career as a psychotherapist. I explore familial effects, the influences of culture and of individual role models, and the impact of the women's movement on my career. I also examine the role that a contrarian, “outside” stance has played in the selection of my career and theoretical orientation. © 2005 Wiley Periodicals, Inc. J Clin Psychol/In Session 61: 949–956, 2005.
What inspired me to become a psychotherapist?
Authors: Mahrer Alvin R.
Published: June 2005

Six answers are given to the question of why I really became a psychotherapist. Of the six answers, three involve what may be considered inspirational influences: the inspirational benefits of what psychotherapy can offer, inspirational teachers, and inspirational practitioners. © 2005 Wiley Periodicals, Inc. J Clin Psychol/In Session 61: 957–964, 2005.
Becoming a multicultural psychotherapist: The confluence of culture, ethnicity, and gender
Authors: Comas‐Díaz Lillian
Published: June 2005

A Latina psychotherapist relates the influences of culture, ethnicity, gender, and class in her process of becoming a psychotherapist. Struggling with physical impediment, cultural translocation, racism, sexism, and their interaction, she has grounded her identity as a wounded healer. The pervasive role of history and sociopolitics in her life has contributed to her articulation of psychotherapy's role in liberation. © 2005 Wiley Periodicals, Inc. J Clin Psychol/In Session 61: 973–981, 2005.
Why I became a (brief) psychotherapist
Authors: Hoyt Michael F.
Published: June 2005

The author describes his development as a psychotherapist. He emphasizes both nurture and nature; he indicates that in addition to factors such as family and professional teachers and the zeitgeist, his choice was prefigured by the calling of character. He also discusses some of the influences that led to and confirmed his interest in approaches that fall under the general theoretical rubrics of brief and narrative constructive forms of therapy. © 2005 Wiley Periodicals, Inc. J Clin Psychol/In Session 61: 983–989, 2005.
Doing something
Authors: McCullough Leigh
Published: June 2005

The author relates her circuitous journey of becoming a psychotherapist, partially from the family ethic of helping others in need, but even more fundamentally from learning, on her grandfather's knee, to study character in the human face. She links those experiences to her love of studying and doing research with videotapes of therapy patients. © 2005 Wiley Periodicals, Inc. J Clin Psychol/In Session 61: 991–997, 2005.
In vitro contraction of lobster (Homarus) ovarian muscle: Methods for assaying contraction and effects of biogenic amines
Authors: Howard David R. , Talbot P.
Published: June 2005

The ovary of the lobster, Homarus americanus, is encased by a nonstriated muscular wall that is thought to contract and extrude the oocytes at spawning. The cells of this lobster ovarian muscle (LOM) are unconventional in that their contractile apparati contain extensive arrays of microtubules in addition to actin and myosin. In this study, we introduce two assays to measure LOM contraction in vitro. One assay ranks the distinct morphological changes that a contracting LOM muscle strip progresses through to quantify the extent of contraction. In the other assay, the distances that the edges of LOM strips travel during contraction are measured from a video monitor to calculate a rate of contraction. Using these assays, we found that compounds that elevate intracellular cAMP (IBMX, forskolin, and dbcAMP) inhibit LOM contraction. The biogenic amines octopamine (OCT), 5‐hydroxytryptamine (5‐HT), and dopamine (DA) were tested for their ability to stimulate LOM contraction in vitro. Octopamine (10−6–10−4 M) significantly stimulates contraction in a dose‐dependent manner, and 5‐HT (10−5–10−3 M) mildly stimulates contraction. Dopamine has no effect on contraction. The opposing effects of forskolin and OCT on LOM contraction indicate that OCT stimulation is not mediated through class two OCT receptors. Therefore, LOM appears to be controlled by either class one OCT receptors or a novel class of OCT receptors. © 1992 Wiley‐Liss, Inc.
Leg development in a frog without a tadpole (Eleutherodactylus coqui)
Authors: Elinson Richard P.
Published: June 2005

Direct developing frogs, like Eleutherodactylus coqui, have deleted the tadpole from their life history. Limb buds appear early and develop continuously through embryonic life. The capacity for autonomous development of E. coqui limb buds was tested by explantation and transplantation. When limb buds were explanted to in vitro culture, they progressed for a few stages and then arrested. When limb buds were transplanted to embryos of a typical tadpole species (Rana pipiens), the buds formed legs with knees, digits, and some cartilage, but they did not elongate. Since limb buds transplanted to various sites on E. coqui embryos tended to develop completely, the limited development of the explants in vitro and the transplants to R. pipiens suggests the presence of a systemic factor in the embryo involved in the normal continuous growth of E. coqui legs. Attempts to demonstrate a role for thyroid hormone have thus far been unsuccessful. © 1994 Wiley‐Liss, Inc.
Enhancement of mouse egg activation by the kinase inhibitor, 6‐dimethylaminopurine (6‐DMAP)
Authors: Moses Ruth M. , Masui Yoshio
Published: June 2005

Metaphase arrest in vertebrate eggs is maintained by the action of cytostatic factor (CSF) on maturation promoting factor (MPF). In amphibian eggs, the kinase inhibitor, 6‐dimethylaminopurine (6‐DMAP) inactivates both CSF and MPF, resulting in the release from metaphase and entry into interphase. In the mouse, 6‐DMAP induces nuclear formation in maturing oocytes, but not in eggs at metaphase II. We found that 6‐DMAP accelerated the transition to interphase in mouse eggs treated with the parthenogenetic agents A23187, cycloheximide, or phorbol 12‐myristate 13‐acetate (PMA). Newly ovulated eggs, refractory to full activation by A23187, entered interphase when treated with A23187 and 6‐DMAP in combination. Occasional batches of eggs formed nuclei in response to 6‐DMAP alone. These results are discussed with regard to the possible effects of 6‐DMAP on MPF and CSF. © 1994 Wiley‐Liss, Inc.
Distal‐less and other homeobox genes in the development of the dentition
Authors: Weiss K. M. , Bollekens J. , Ruddle F. H. , Takashita K.
Published: June 2005

The mammalian tooth develops through an interaction between two tissue layers of different embryologic origin. A number of transcription factors and as well as two members of the Msx class of homeobox genes have been shown to be involved in the histogenesis of the mammalian tooth. This raised the possibility that other homeobox genes might be involved in dental morphogenesis. We have amplified mouse tooth germ cDNA from three different gestational ages by the polymerase chain reaction with degenerate primers for 18 classes of homeobox genes. Members of several classes have been isolated, including the Msx genes, two Dlx genes, and the Dbx, MHox, Mox2A genes. One of the Dlx genes, Dlx‐7, had not previously been reported in mammals, and some details are presented of its cDNA sequence. This work plus that of other investigators has shown that at least six Dlx genes are expressed in developing teeth or in first branchial arches, suggesting the possibility that these genes are involved in specifying complexity within or between teeth. The screening approach with degenerate primers is a successful way to identify new as well as previously known regulatory genes expressed in developing tooth embryos. © Wiley‐Liss, Inc.
Effects of 5‐fluorouracil on macromolecular synthesis during secondary palate development in quail
Authors: Shah Ravindra M. , Cheng Kimberly M. , Feeley Elizabeth J. E.
Published: June 2005

A study was undertaken to examine the growth of normal and 5‐fluorouraciltreated quail secondary palate during embryogenesis. The rates of DNA, RNA, and protein synthesis were measured in the developing quail palate by liquid scintillation counting of radiolabelled thymidine, uridine, or leucine. In addition, shelf volume was determined morphometrically. The results showed that in control palates the shelf volume increased rapidly between days 5 and 7 of incubation. Drug treatment on day 4 did not alter the shelf volume until day 9 of incubation, at which time the treated shelves were smaller than controls. In control palates, the rate of DNA synthesis decreased steadily between days 5 and 9 of incubation. A burst in RNA synthesis on day 7 of incubation was followed by an increase in protein synthesis. Administration of FU seems to exert its effect via disturbing the synthesis of RNA and protein, instead of disruption of DNA synthesis, to ultimately affect the shelf area, and thus palate morphogenesis in quail. Comparison of avian and mammalian data indicated that differences in their palate morphogenesis are also reflected in the different temporal patterns of various macromolecular synthesis. © 1994 Wiley‐Liss, Inc.
Mechanism of cytotoxic activity by hemocytes of the solitary ascidian, Ciona intestinalis
Authors: Peddie Clare M. , Smith Valerie J.
Published: June 2005

The mechanism of cytotoxicity by the hemocytes from the solitary ascidian, Ciona intestinalis, against the target cell WEHI, a mouse myelomonocytic leukemic cell (strain 3B), was investigated in vitro. Experiments using chelators of Mg2+ and Ca2+ show that the cytotoxic activity by these hemocytes involves at least two stages distinguishable by their divalent cation requirements. In particular removal of both Ca2+ and Mg2+ by EDTA inhibits effector to target cell conjugate formation and target cell lysis, whereas selective removal of Ca2+ by EGTA inhibits target cell lysis but does not reduce the formation of effector to target cell conjugates. Evidence that cytotoxic activity is reduced by sodium azide, cytochalasin B, colchicine, vinblastine sulfate, and monensin, indicates that the response involves energy metabolism, requires an intact cyto‐skeleton, and entails active secretory processes in the effector cells. In addition, cytotoxic activity is probably not mediated by superoxide anions or hydrogen peroxide, because the antioxidant enzymes, superoxide dismutase, and catalase did not affect target cell lysis. It is therefore likely that cytotoxic activity by the hemocytes from C. intestinalis is mediated by mechanisms similar to those of vertebrate cytotoxic cells. © Wiley‐Liss, Inc.
Localization of ecdysteroid receptor immunoreactivity in eyestalk and muscle tissue of the American lobster, Homarus americanus
Authors: El Haj A. J. , Harrison P. , Chang E. S.
Published: June 2005

Ecdysteroid receptor immunoreactivity (EcR) has been identified in walking leg extensor muscle and eyestalk neural tissue of the American lobster, Homarus americanus, using a monoclonal antibody to the EcR of Drosophila melanogaster. Western blots using the EcR antibody, hybridized with a 95–110 kDa protein from the lobster tissues examined. Premoult muscle and hypodermis, and eyestalk neural tissue cross‐reacted with the antibody as evidenced with immunocytochemistry. Sections of eyestalk neural tissue showed cytoplasmic localization of the EcR in the neural cells associated with the X‐organ/sinus gland complex. © Wiley‐Liss, Inc.
Water relations in nocturnal and diurnal foragers of the desert honeypot ant Myrmecocystus: Implications for colony‐level selection
Authors: Duncan Frances D. , Lighton John R. B.
Published: June 2005

The desert honeypot ant genus Myrmecocystus contains both diurnal and nocturnal species, which are subject to very different desiccation challenges when foraging. We measured water loss rates (WLRss) of live and dead M. mexicanus and M. mendax workers (nocturnal and diurnal foragers, respectively) in still and moving air at 30°C. In M. mendax, air flow and vital state significantly affected WLR; death increased WLR, as did air flow (but only in live ants). The WLR of M. mexicanus was unaffected by flow or vital state and was generally equivalent to that of M. mendax. Cuticular permeabilities of both species 10–20 μg H2 cm−2 h−1 Torr−1) are similar to values for other xeric insects. The mean body water content of both species was very high at 84% of live body mass. Coordination failed after losing 71% (M. mexicanus), and 51% (M. mendax), of total original body water reserves. Paradoxically, therefore, the diurnal M. mendex workers are operationally more sensitive to desiccation; accordingly, in a desiccating environment they lost coordination more rapidly than M. mexicanus workers (mean 27 vs. 59 hr). We therefore found no evidence that WLRs or dehydration sensitivities of these worker ants reflected the differing dehydration challenges imposed by diurnal vs. nocturnal foraging strategies and suggest that this may reflect similar selective pressures not on workers, but on female reproductives during colony foundation. © Wiley‐Liss, Inc.
Effects of season and photoperiod on the plasma and intratesticular testosterone levels in Indian weaver birds inhabiting the subtropical zone
Authors: Tsutsui Kazuyoshi , Saxena Tanushri , Saxena Rajendra N.
Published: June 2005

Previous studies showed marked changes in the plasma gonadotropin concentration in response to fluctuations in natural and artificial environmental conditions in Indian weaver birds. Therefore, we studied the effects of season and photoperiod on the plasma and intratesticular testosterone levels in this subtropical bird. Although the plasma testosterone concentration changed markedly during the annual breeding cycle, the level did not show a parallel change with testicular weight. The testicular weight was maximal in the breeding phase (June) and minimal in the nonbreeding phase (December), while the plasma testosterone concentration showed two large peaks, one in the breeding and the other in nonbreeding phases. No significant difference in the plasma testosterone level was detected between these two phases. A similar change in plasma testosterone levels was evident in female birds. The intratesticular testosterone content per unit weight was unexpectedly higher in the nonbreeding phase than in the breeding phase. Therefore, calculated total testosterone content per testis showed no statistically significant difference between the two phases despite the small testicular mass in the nonbreeding phase. On the other hand, exposure to short‐day (SD) photoperiods for 10 weeks during the breeding phase, which caused a marked decrease in the testicular weight, tended to decrease the plasma testosterone concentration. Similarly, exposure to long‐day (LD) photoperiods for 10 weeks during the nonbreeding phase tended to induce an increase in the circulating testosterone level in addition to a marked increase in the testicular weight. However, such an effect of artificial photoperiod on testosterone levels was statistically not significant due to a large variance. These results suggest that in Indian weaver birds testosterone actively circulates not only in the breeding phase but also in the nonbreeding phase. Not only photoperiod but also other environmental factors may be involved in the regulation of circulating testosterone in male birds. © Wiley‐Liss, Inc.
Oocyte nuclear maturation at the time of oocyte aspiration is independent of in vitro fertilization potential in the domestic cat
Authors: Byers A. P. , Donoghue A. M. , Roth T. L. , Wildt D. E.
Published: June 2005

This study determined (1)the temporal kinetics of nuclear maturation at and after follicular oocyte aspiration and (2) the significance of variations in nuclear maturation and sperm‐oocyte co‐incubation interval on in vitro fertilization (IVF) in the domestic cat. Female cats were treated with pregnant mares' serum gonadotropin followed 84 h later with human chorionic gonadotropin (hCG). Twenty‐five hours after hCG, ovarian follicular oocytes were aspirated laparoscopically and classified according to morphological criteria. Oocytes classified as mature were cultured for 0,2,4,6, or 8 h in Ham's F10 medium and then stained for nuclear maturation. The proportion of oocytes at metaphase II was similar (P > 0.05) at 0 (38.2%) and 2 (48.5%) h of culture, but was higher (P < 0.05) at 4 (76.5%), 6 (82.8%), and 8 (92.3%) h. Oocytes also were collected and cultured as described above and then co‐incubated for 2 or 18 h with 5 × 105 motile cat sperm cells/ml. The incidence of IVF (cleavage to 2‐cells by 30 h post‐insemination) was consistently 2‐fold higher (P > 0.05) for the 18 h compared to the 2 h gamete co‐incubation groups. However, despite differences in nuclear maturation at the time of oocyte recovery, IVF success was unaffected (P > 0.05) by pre‐insemination culture interval (0 h, 72.7%; 2 h, 73.3%; 4 h, 70.7%; 6 h, 57.8%; 8 h, 62.5%; 18 h group). Thus, the majority of oocytes recovered from cats treated with this gonadotropin regimen has not achieved metaphase II by follicular aspiration. These oocytes appear grossly mature, but nuclear maturation often is incomplete until 4–8 h in culture. Ability of these oocytes to fertilize in vitro is independent of stage of nuclear maturation at recovery, but IVF success is influenced by sperm‐oocyte co‐incubation interval. © Wiley‐Liss, Inc.
Midgut metabolism in different instars of the tobacco hornworm (Manduca sexta)
Authors: Gibellato C. M. , Chamberlin M. E.
Published: June 2005

Enzyme activities and mitochondrial substrate oxidation were measured in the posterior midguts of tobacco hornworms at different larval stages. A comparison of third, fourth, and fifth instars demonstrated no differences in citrate synthase activity (per gram of midgut), indicating that maximal aerobic capacity is unchanged during larval growth. The midguts of fifth instars had the highest activity of 3‐hydroxyacyl‐CoA dehydrogenase and carnitine acetyltransferase. Furthermore, mitochondria isolated from the midguts of fifth instar larvae had higher rates of palmitoyl carnitine oxidation when compared to mitochondria isolated from the fourth instar larvae. These results indicate that there is an increased preference for fatty acid oxidation in the midguts of fifth instar larvae. The presence of succinyl‐CoA ketotransferase and acetoacetyl‐CoA thiolase as well as the mitochondrial oxidation of acetoacetate and β‐hydroxybutyrate indicate that ketone bodies can serve as substrates for the midgut. The activities of malic enzyme and glucose‐6‐phosphate dehydrogenase were significantly higher in fifth instars than in fourth instars, indicating an increased capacity for lipid synthesis. © Wiley‐Liss, Inc.
Characterization of partially purified betaine aldehyde dehydrogenase from horseshoe crab (Limulus polyphemus) cardiac mitochondria
Authors: Dragolovich Julia , Pierce Sidney K.
Published: June 2005

Glycine betaine is an organic osmolyte which is often accumulated in response to hyperosmotic stress in euryhaline species. In mitochondria isolated from horseshoe crab (Limulus polyphemus) heart tissue, the synthetic pathway, which is a two step oxidation of choline (choline→betaine aldehyde→glycine betaine), appears to be associated with the matrix. The majority of the betaine aldehyde dehydrogenase (BADH) activity, the terminal synthetic enzyme, is found in this subcellular fraction. Partially purified Limulus BADH is highly specific for the substrate betaine aldehyde (Km of 133 μM). Two alternative substrates, glyceraldehyde and glycoaldehyde, do not stimulate NAD+ reduction in the presence of BADH. NAD+ is an essential co‐factor in the oxidation of betaine aldehyde to glycine betaine. Limulus BADH can utilize NADP+, although a higher Km indicates a much lower affinity than that for NAD+, 267 μM and 22 μM, respectively. The end‐product, glycine betaine, competitively inhibits BADH activity. Cations have a profound effect on Limulus BADH activity. At physiological concentrations, enzyme activity is stimulated by increases in both [K+] but decreased by elevated [Na+]. Although inorganic ions modulate this enzyme, it does not appear that BADH is the rate limiting step in osmotically stimulated glycine betaine synthesis. © Wiley‐Liss, Inc.
Elevated ornithine decarboxylase activity and polyamine levels during early development in the brine shrimp Artemia franciscana
Authors: Watts Stephen A. , Lee Kara J. , Cline George B.
Published: June 2005

Rehydrated Artemia cysts were assayed for ornithine decarboxylase (ODC) activity and levels of putrescine, spermidine, and spermine during pre‐emergent development, emergence and hatching. Low but detectable ODC activity levels increased significantly within 2 hr, suggesting de novo synthesis of ODC protein and representing one of the earliest enzymatic biochemical markers in post dormancy development. ODC activity increased 100‐fold during preemergent development (occurring in the absence of an increase in tissue polyamine content). This increase in enzyme activity occurs in the relative absence of DNA synthesis but may be related to an enhanced polyamine synthetic capacity necessary for other physiological processes such as early transcriptional and translational activity. A second, higher ODC activity peak (correlated with a significant increase in polyamines) prior to hatching may be related to DNA synthesis and other biochemical processes associated with hatching of stage 1 nauplii and is correlated with increasing ecdysteroid titres reported previously. Putrescine and spermidine levels were significantly higher than spermine levels (2.5, 2.65, and 0.13 μmoles/g dry weight) at the onset of rehydration. High endogenous polyamines levels in encysted embryos are most likely available for use in metabolic processes associated with early differentiation. Polyamine levels increased significantly just prior to emergence and continued increasing throughout hatching. Spermidine to spermine ratios (>18) should reflect high rates of overall biosynthetic processes throughout preemergence, emergence, and hatching. © Wiley‐Liss, Inc.
Heat and oxygen flux as a function of environmental po2 in juvenile Australian crayfish, Cherax quadricarinatus
Authors: Meade Mark E. , Doeller Jeannette E. , Kraus David W. , Watts Stephen A.
Published: June 2005

Oxygen and heat flux of the juvenile Australian red claw crayfish, Cherax quadricarinatus, were measured in parallel respirometry and calorimetry systems at 28°C at varying levels of environmental po2. Juvenile crayfish maintained an average oxygen flux of 5.0 ± 0.4 (SEM) pmol O2/(s*mg fresh weight) over the po2 range from 20.7 to 5 kPa. At approximately 4 kPa po2, oxygen flux decreased, conforming to decreasing oxygen tensions. Juvenile crayfish maintained an average heat flux of −2.2 ± 0.2 μW/mg fresh weight when exposed to 100 and 50% air saturated conditions (18.1 to 20.7 and 7.8 to 10.4kPa po2, respectively). The ratio of the amount of heat dissipated per oxygen consumed, called the calorimetric/respirometric (CR) ratio, at 100 and 50% air saturated conditions averaged −440 kJ/mol O2. When crayfish were exposed to 25% air saturated conditions (2.5 to 5.2 kPa po2), heat flux decreased initially to −1.1 ± 0.4 μW/mg fresh weight. Within 4 hr, however, heat flux returned to normoxic values. When crayfish were exposed to anoxic conditions, heat flux decreased to zero. Most juvenile crayfish did not survive short‐term (1–2 hr) anoxic stress. These data suggest that juvenile C. quadricarinatus are excellent oxygen regulators over a wide range of environmental po2. These data indicate also that juvenile C. quadricarinatus can compensate metabolically, possibly via aerobic and/or anaerobic adjustments, in order to maintain metabolic rate at critically low po2. Last, this crayfish appears limited in its ability to utilize anaerobic pathways to maintain metabolic rate in anoxic environments. © Wiley‐Liss, Inc.
Study of the regenerating newt retina by electrophysiology and immunohistochemistry (bipolar‐ and cone‐specific antigen localization)
Authors: Saito T. , Kaneko Y. , Maruo F. , Niino M. , Sakaki Y.
Published: June 2005

Immunohistochemical and electrophysiological examinations were carried out to investigate the sequence of appearance of the retinal neurons during regeneration after a complete surgical removal of the original retina of the newt. We produced a monoclonal antibody, RB‐1, specific for cone photoreceptors and a subtype of bipolar cells in adult newt retina. This antibody was used as a major tool for this analysis. Appearance of spiking activity as a possible marker of ganglion cell differentiation was examined with whole‐cell patch‐clamp techniques. Spiking cells, which possessed voltage‐dependent Na+, K+, and Ca2+ channels similar to those of mature ganglion cells, appeared in the regenerating retina by 24 days before cone photoreceptors had been labeled by the RB‐1 antibody. Cones and ganglion cells differentiated before the retina had been segregated into distinct synaptic layers. The RB‐1‐labeled bipolar cells as well as PKC‐immunoreactive bipolar cells appeared in the regenerating retina after the segregation of the synaptic layers. Their appearance seemed to coincide with the appearance of immunoreactive amacrine cells described previously (Negishi et al. [1992] Dev. Brain Res. 68:255–264). During embryonic development of the newt retina, cone photoreceptors appeared prior to bipolar cells. Thus the process of reformation of a functional retina seems to follow the same steps as differentiation of retina during development. © Wiley‐Liss, Inc.
Calcium‐binding properties of fetuin in fetal bovine serum
Authors: Suzuki Michiko , Shimokawa Hitoyata , Takagi Yuzo , Sasaki Satoshi
Published: June 2005

Fetuin, an abundant protein in fetal bovine plasma, is the bovine homolog of human α2HS glycoprotein (α2HS). In spite of numerous studies, the biological functions of both proteins remain elusive. We now report the remarkable 45Ca‐binding activity of fetuin in fetal bovine serum that has been blotted on a membrane after electrophoresis. The Ca‐binding ability of the purified protein was analyzed by equilibrium dialysis, which revealed that bovine fetuin had multiple Ca‐binding sites, one of which had a Kd of 0.95 × 10−4 M. It was also shown that the Ca‐binding activity of fetuin was greater than that of albumin in serum of the bovine fetus at the late gestational stage. Since fetal bovine serum contains not only a high concentration of fetuin but also a high concentration of Ca, it is possible that fetuin functions to maintain high levels of Ca in fetal serum via normalization of the concentration of Ca2+ ions. © Wiley‐Liss, Inc.
Localization of proline receptors involved in regulating nematocyst discharge
Authors: Watson Glen M. , Roberts Julia
Published: June 2005

At least two distinct classes of chemoreceptor are known to regulate nematocyst discharge in sea anemones. One class of receptor binds N‐acetylated sugars and the other class binds certain amino compounds including the imino acid, proline. Previously, receptors for N‐acetylated sugars were localized using colloidal gold conjugates of bovine submaxillary mucin. The sugar receptors are known to cycle by receptor‐mediated endocytosis from the apical surface of supporting cells. In this study, colloidal gold conjugates of polyproline were used to determine the distribution of proline receptors. We find that polyproline‐gold, like mucin‐gold, localizes to the apical surface of supporting cells. Binding of polyproline‐gold to supporting cells is blocked by excess free polyproline or free proline. After appearing at the cell surface, polyproline‐gold enters endosomes, followed by multivesicular bodies. To test for possible artifact due to colloidal gold, trafficking of cationized ferritin (CF) was monitored in the presence of proline. CF appears at the cell surface, followed by endosomes, multivesicular bodies, and lysosomes. Some evidence is presented that proline receptors are sorted from N‐acetylated sugar receptors in endosomes. We propose that receptor‐mediated endocytosis functions in anemone tentacles to enhance the temporal resolution of chemosensing. © Wiley‐Liss, Inc.
Snake yolk sac as a site for in vivo organ incubation: A new method in the research of snake embryo development
Authors: Reshef Ram , Ovadia Michael , Wollberg Miriam , Kochva Elazar
Published: June 2005

The snake embryo yolk sac served as a culture medium for the development of isolated reptilian organs. Isolated upper jaws of Natrix tessellata and Vipera palaestinae embryos at the early stages of jaw organogenesis were implanted into the yolk, close to the yolk sac blood vessels of Natrix tessellata embryos in order to determine natural conditions for long‐term incubation of organ culture. Tissues were incubated in the yolk for approximately 1 month until 1 day before host embryo hatching. Histological inspection showed full morphological differentiation of all tissues including scales, bones, teeth, glands, and connective tissue. The biochemical marker phosphodiesterase showed the typical developmental pattern in the main oral gland, Duvernoy's gland, and was comparable to the same gland in the host embryo. Vipera implants developed almost normally, except for differentiation of the skin which remained in the stage of one to two cell undifferentiated layers. Natrix was chosen for these experiments owing to the special chemical composition of its yolk that allows the penetration of blood vessels. This characteristic is probably crucial for the success of angiogenesis, which in turn is an essential condition for tissue survival. The ability of the yolk to support normal differentiation of isolated organs provides a valuable tool for the long‐term incubation experiments that are indispensable in order to achieve maximal tissue differentiation. © Wiley‐Liss, Inc.
Fiber types and myosin heavy chain composition in muscles of common shrew (Sorex araneus)
Authors: Savolainen Jukka , Vornanen Matti
Published: June 2005

Red‐toothed shrews of subfamily Soricinae are small mammals with very high mass‐specific metabolic rate. Owing to their high aerobic power they are interesting objects for studies concerning the limits and constraints of skeletal muscle adaptation. In order to clarify the correlation between metabolic rate and muscle properties, we have analyzed fiber types, fiber size, and myosin heavy chain composition of the common shrew(Sorex draneus)and compared them to those of rat (Rattus norvegicus).

Three distinct differences between shrew and rat muscles were noted. 1) The fibers of shrew muscles are exceptionally small in comparison to rat myofibers. 2) Electrophoretic and histochemical analysis showed that shrew muscles are composed of only fast fibers (fiber types IIB and IID), the slow type I fibers being totally absent. 3) The shrew muscles are much more homogenous than rat muscles in regard to myosin heavy chain and fiber type composition. The shrew diaphragm consists exclusively myosin heavy chain type IId (MHCIId), while masseter and soleus are composed 95% and 87% of MHCIId, respectively. Other four studied muscles contain MHCIIb and MHCIId approximately in equal proportions.

The present findings show that shrew muscles are composed of small, highly aerobic, fast type II fibers, which may be sufficiently fatigue‐resistant to function both as postural muscles and to power fast and high frequency movements of limbs and diaphragm. © 1995 Wiley‐Liss, Inc.
External and internal influences on indices of physiological stress. I. Seasonal and population variation in adrenocortical secretion of free‐living lizards, Sceloporus occidentalis
Authors: Dunlap Kent D. , Wingfield J. C.
Published: June 2005

The plasma levels of glucocorticoid hormones (e. g., corticosterone and cortisol) are often used as an index of physiological stress. However, under natural conditions, glucocorticoid secretion can respond to both environmental influences (e. g., extreme climatic conditions) and internal influences (populational differences and annual seasonal cycles). To distinguish between these kinds of influences, we examined seasonal variation in basal levels of corticosterone and the adrenocortical response to acute stress in six populations of western fence lizards Sceloporus occidentalis. Three populations (Mojave CA, Lone Pine CA, and Tulalip WA) were near the periphery of the species distribution, and three were in the central part of the range (Ojai CA, Hopland CA, and Bend OR). Basal corticosterone showed no consistent pattern of variation, but the adrenocortical response to acute stress was consistently highest 1) in populations living at the margin of the species range, 2) during the hottest and driest seasons, and 3) in individuals with the largest decrements in physiological condition (length‐adjusted mass). Thus, basal adrenal secretion and adrenal responsiveness to acute stress were dissociated, and the latter more likely reflected the physiological condition of an individual and the severity of its environment. However, further analysis showed that physiological condition only partially explains the variation in adrenocortical responsiveness and that intrinsic seasonal and population differences may be as important as the external influences of the physical environment. After factoring out seasonal changes in physiological condition, adrenocortical response of two populations under identical controlled laboratory conditions also showed that a peripheral population (Mojave, CA) maintained a higher response than a central population (Bend, OR) that was not attributable to population differences in physiological condition. © 1995 Wiley‐Liss, Inc.