bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Oestradiol, Progesterone and Heparin on Bovine Spermatozoa Function After Thawing
Authors: Lukoseviciute K , Zilinskas H , Januskauskas A
Published: March 2005

Contents

The present experiment was designed to determine the effects of various biologically active substances, such as oestradiol (OE), progesterone (P4) and heparin (Hep) alone or in combination on sperm plasma membrane scrambling, capacitation and acrosome reaction (AR) of post‐thaw bovine spermatozoa. Spermatozoa were incubated for 180 min in capacitation medium supplemented with (i) 1 μg/ml OE; (ii) 1 μg/ml P4; (iii) 1 μg/ml OE and 1 μg/ml P4; (iv) 1 μg/ml OE and 5 μg/ml Hep; (v) 1 μg/ml P4 and 5 μg/ml Hep; (vi) 1 μg/ml OE, 1 μg/ml P4 and 5 μg/ml Hep. At predetermined time intervals aliquots were taken to assess sperm plasma membrane scrambling, or capacitation (AR induced by lysophosphatidylcholine) in spermatozoa. The second experiment was aimed to study the effects of OE, P4 and OE/P4 as potential inducers of AR in Hep‐capacitated spermatozoa. Plasma membrane scrambling was assessed by a flow cytometer, using Merocyanine staining. Acrosomal status and viability of spermatozoa were evaluated under epifluorescence microscope with Ethidium homodimer‐1/peanut agglutinin fluorescein isothiocyanate staining method (EthD‐1/PNA‐FITC). The results show that OE, P4 and a combination of OE/P4 at concentrations used did not affect sperm viability. Heparin significantly (p < 0.001) increased sperm plasma membrane scrambling of OE and P4‐treated spermatozoa. P4 significantly affected the rate of sperm capacitation (p < 0.001) and AR (p < 0.05), but OE expressed membrane‐stabilizing properties (p < 0.05). It can be concluded that in frozen–thawed bovine spermatozoa OE presents plasma membrane stabilizing properties that can be abolished by Hep, but not by P4. Progesterone possesses capacitating and AR‐inducing properties in frozen–thawed bovine spermatozoa that can be alleviated by OE.
In vitroEvaluation ofin vivoFertilizing Ability of Frozen Rabbit Semen
Authors: Viudes‐de‐Castro MP , Mocé E , Vicente JS , Marco‐Jiménez F , Lavara R
Published: March 2005

Contents

The present work studied different spermatozoa parameters and the ability of frozen rabbit spermatozoa to fertilize,in vitro,in vivo‐matured oocytes, as a test to predict theirin vivofertility and prolificacy. Semen from rabbit bucks was frozen using two freezing protocols [in a freezer at −30°C or in liquid nitrogen vapour (LNV)]. For thein vivotrial, females were inseminated with frozen‐thawed spermatozoa. Oocytes used forin vitrotesting were recovered 14 h after ovulation induction from donors and co‐incubated with 2 × 106frozen‐thawed spermatozoa during 4 h at 37°C in Tyrode's medium under an atmosphere of 5% CO2in air with maximal humidity. After co‐incubation period, presumptive zygotes were cultured in TCM199 supplemented with 20% foetal bovine serum (FBS), under the same conditions described above. Although no statistical differences were observed between freezing protocols in seminal parameters [motility rate: 40 and 35%, VCL: 35 and 46 μm/s, amplitude of lateral head displacement (ALH): 1.7 and 2.4 μm, for semen frozen at −30°C and in LNV, respectively], significant differences were noted in the fertilizing abilityin vivoandin vitro. Semen frozen at −30°C showed the highest fertilizing abilityin vitro(26.7% vs 6.2 and 8.7% for semen frozen at −30°C, in LNV and fresh semen, respectively) and the lowest fertility ratein vivo(21.7% vs 64.2% and 70.6% for semen frozen at −30°C, in LNV and fresh semen, respectively). Sperm frozen at −30°C seemed to be more capacitated.
Free Oestrone in Adipose Tissue and its Relation to Androstenone and Skatole in Entire Male Pigs
Authors: Zamaratskaia G , Madej A , Babol J , Squires EJ , Lundström K
Published: March 2005

Contents

Relationship between free oestrone and boar taint compounds in adipose tissue were studied in two groups of entire male pigs of different breeds. Group A consisted of 33 entire crossbred male pigs (dam Yorkshire and sire backcross Yorkshire × Wild Boar, generation seven). Group B consisted of 194 entire male pigs of crossbreeds between Swedish Hampshire (H) and Finnish Landrace (L), LH × H, H × LH, LH × LH (dam × sire). The measurements of free oestrone in adipose tissue were performed with a new method developed and validated in our laboratories. The standard curve was linear for concentrations of free oestrone ranging from 0.13 to 5.10 ng/g. The method exhibited parallelism of results between serial dilutions and a mean recovery of 97 ± 13.7%. Intra‐assay variations for samples with concentrations of free oestrone from 0.67 to 2.08 ng/g were from 9.23 to 11.94%. Inter‐assay variations for the samples with concentrations of free oestrone from 0.89 to 2.96 ng/g were from 3.78 to 10.11%. The levels of free oestrone in fat from group A were well correlated with fat levels of androstenone (r = 0.66; p < 0.001) and levels of oestrone sulphate in peripheral plasma collected at the same time as the fat (r = 0.74, p < 0.001). The levels of free oestrone in fat from group B were significantly correlated to fat levels of androstenone (r = 0.68, p < 0.001) and skatole (r = 0.29, p < 0.001). In group B, age‐related differences in fat levels of free oestrone, androstenone and skatole were studied. Free oestrone and skatole levels increased simultaneously at the age of 22 week (p < 0.05 for both), and androstenone levels increased at the age of 26 week (p < 0.05). It was suggested that the levels of free oestrone in adipose tissue might be used for the evaluation of hormonal status of male pigs as an alternative to plasma levels of testicular hormones. The levels of free oestrone might be involved in the regulation of skatole levels in fat as indicated by both the simultaneous increases in skatole and free oestrone levels in fat and positive correlation between skatole and free oestrone.
Using the Milan approach in the inpatient management of anorexia nervosa (varying the‘invariant prescription’)
Authors: Vaz‐Leal Francisco J. , Salcedo‐Salcedo M. Soledad
Published: March 2005

This paper proposes a model of treatment for severe anorexia nervosa which integrates hospitalization, individual psychotherapy and family therapy. Family intervention is based on a method proposed by the Milan team (the‘invariant prescription’), which has been adapted by the authors to suit the characteristics of their working context (the psychiatric unit of a general hospital). Following a review of the work of Selvini Palazzoli and associates on anorexia nervosa and the‘invariant prescription’, the authors describe their treatment model and give a case example.
The real as illusion: deconstructing power in family therapy
Authors: Larner Glenn
Published: March 2005

This paper examines the current issue of power and intervention in family therapy from the perspective of Jacques Derrida's philosophy. In a deconstructive reading which presents power as both real and socially constructed, it negotiates the border between such dualities as knowing/ not‐knowing, intervention/non‐intervention, and power/non‐power. The paper tracks Goolishian and Anderson's approach to therapy as deconstructive in practice, but not in theory, and discusses a double view of power in relation to both Bateson and Foucault. It suggests that power is both endemic to the context of family therapy and an illusion of epistemology. The paper concludes with a discussion of the wider question of ethics in relation to technology.
Family work for schizophrenia: some issues for Chinese immigrant families
Authors: Lam Dominic H. , Chan Nancy , Leff Julian
Published: March 2005

This paper discusses some specific issues relevant to immigrant Chinese families in the context of family work for schizophrenia. The issues include shame and guilt, isolation and mistrust of officials, the importance of negotiation before details of problem‐solving are worked out, high academic ambitions for children, and apparent ‘overprotectiveness’ in the Chinese culture. It is argued that cognitive‐behavioural, goal‐orientated family work could be adapted well for immigrant Chinese families with a member suffering from schizophrenia. A case study is presented to illustrate how such a family was helped.
Theme‐focused family therapy: the inner emotional world of the family
Authors: McCluskey Una , Miller Liza Bingley
Published: March 2005

This paper is an account of a method of family work developed for social workers in social services departments which allows them to work with the emotional impact on children and adults of traumatic events in family life. Theme‐focused family therapy has been designed to meet the needs of the families and also to enable social workers and their supervisors to develop both psychodynamic and systemic perspectives m their work with families. It is a staged approach, moving from individual work to a structured family interview through to a series of theme‐focused family sessions. It is phased in this way both to facilitate the development of a therapeutic attachment between social worker and family and to take account of the crises that can interrupt planned work in social services departments. Theme‐focused family therapy is carried out in partnership with families, and gives children a voice and a leading role in the therapeutic process. The approach is illustrated with a case example.
Engaging with change: a process study of family therapy
Authors: Frosh Stephen , Burck Charlotte , Strickland—Clark Lisa , Morgan Kevin
Published: March 2005

It is argued that current attempts to investigate the process of family therapy might benefit from the application of discursive and narrative analytic techniques. An example of such an analysis is given, taking the work of an experienced family therapist with one family seeking help in dealing with the aftermath of a marital separation.‘ The theme of how to deal with change’as it materializes in the discussions during therapy is selected for detailed examination in this paper. It is argued that there are two main discourses on this theme evident in the family's discussions, one being that the separation has occurred and its consequences should now he left to arise naturally; the other being that the effects of the separation need to be actively managed. It is suggested that this analytic procedure can dramatize the subtle changes in family discourses during therapy; its limitations in terms of generalizability, and the difficulties of dealing with huge amounts of complex material, are also noted.
Family therapy for adolescents diagnosed as having borderline personality disorder
Authors: James Anthony C. , Vereker Margaret
Published: March 2005

The family therapy of twenty‐four cases of adolescents diagnosed as having borderline personality disorder is described. In comparison to matched psychiatric controls, the families of these adolescents were more angry and irritable and had higher rates of sexual abuse and sibling psychopathology. Relationship difficulties, in particular oscillating attachments, were frequently seen in therapy, which was more tumultuous with frequent impulsive acts of self‐harm.
ETERNITY, TIME, AND SPACE
Authors: Pannenberg Wolfhart
Published: March 2005

Abstract. The concepts of space and time are important in physics and geometry, but their definition is not the exclusive prerogative of those sciences. Space and time are important for ordinary human experience, as well as for philosophy and theology. Samuel Clarke, Gottfried Wilhelm Leibniz, Isaac Newton, Immanuel Kant, and Albert Einstein are important figures in shaping our understandings of space, time, and eternity. The author subjects their arguments to critical examination. Space is neither an infinite and empty receptacle (Newton) nor a system of relations in the mind (Leibniz). Infinite space and time can be interpreted as expressing God's eternity and omnipresence in relating to the creation (Clarke), but such an interpretation is enhanced by Kant's thinking, to clarify that even though time and space are differentiated in individual events, the whole is at the same time present. Even human experience recognizes this wholeness, and for God eternity is the simultaneous presence and possession of the wholeness. The temporal existence of finite entities is also related to a future participation in God's eternal life. Concepts of contingency are brought into the discussion as well.
Effects of baroreceptor stimulation and opioids on the auditory startle reflex
Authors: Nyklíc̆ek Ivan , Wijnen Viona , Rau Harald
Published: March 2005

We examined (a) whether carotid baroreceptor stimulation attenuates the auditory startle response and its modulation by preceding affective pictures, and (b) whether these effects are mediated by endogenous opioids. Seventy‐eight young normotensive adults with or without a parental history of hypertension received brief exposures to affective pictures and noise bursts during phasic manipulation of the carotid baroreceptors. In each participant, opioids were blocked by naltrexone in half of the sessions. Baroreceptor stimulation had a strong dampening effect on the startle response. This effect was not influenced by opioid blockade, sex, or parental history of hypertension. No baroreceptor effects were obtained regarding ratings of the affective pictures or startle modulation by the pictures. The baroreceptor stimulation effects seem to be mediated by the basal primary acoustic startle circuit rather than by higher affective circuits.
Paradoxal effect of salbutamol in an in vitro model of bronchoprotection
Authors: Girodet P.O. , Berger P. , Martinez B. , Marthan R. , Advenier C. , Molimard M.
Published: March 2005

Salbutamol‐induced hyperresponsiveness to acetylcholine was investigated in human and guinea‐pig isolated airways and cultured human airway smooth muscle cells. Salbutamol (10−7–10−5 m) inhibited contractions induced by low concentrations of acetylcholine (10−8–10−7 m) but potentiated contractions induced by higher concentrations of acetylcholine (10−5–10−3 m). Pretreatment with the calcium channel antagonist nicardipine suppressed salbutamol‐induced hyperresponse. Stimulation of cultured human airway smooth muscle cells with salbutamol (10−6 m) amplified intracellular calcium concentration rise induced by acetylcholine (10−5 m). Propranolol (10−7 m), a β1‐ and β2‐adrenoceptor antagonist, and ICI 118551 (10−7–10−6 m), a β2‐adrenoceptor antagonist, suppressed the inhibitory effect of salbutamol but did not inhibit the hyperresponse on high concentrations of acetylcholine. In contrast, higher concentration of propranolol (10−6 m) inhibited salbutamol‐induced hyperreactivity. Effects of salbutamol were not affected by atenolol, a β1‐adrenoceptor blocker. Salbutamol‐induced hyperresponsiveness is mediated through a mechanism involving calcium channel activation.
Taurine treatment protects against chronic nicotine‐induced oxidative changes
Authors: Şener Göksel , Özer Şehirli A. , İpçi Yeşim , Çetinel Şule , Cikler Esra , Gedik Nursal , Alican İnci
Published: March 2005

Experiments have shown that chronic nicotine administration caused oxidative damage in various organs by increasing lipid peroxidation products and decreasing the activity of endogenous antioxidants. The aim of this study was to investigate the effects of taurine treatment on nicotine‐induced oxidative changes in rat thoracic aorta and heart and to explore the possible mechanisms of action. Male Wistar albino rats (200–250 g) were injected with nicotine hydrogen bitartrate (0.6 mg/kg; i.p.) or saline for 21 days. Taurine was administered (50 mg/kg; i.p.) alone or along with nicotine injections. After decapitation, the thoracic aorta and heart tissues were excised. The aorta was used for in vitro contractility studies or stored along with the heart samples for the measurement of malondialdehyde (MDA) and glutathione (GSH) levels, myeloperoxidase (MPO) activity and collagen content. Tissue samples were also examined histologically. Serum samples were stored for the measurement of MDA, GSH and lactate dehydrogenase (LDH) activity. Chronic nicotine treatment impaired both the contraction and relaxation responses of the aortic rings to phenylephrine and acetylcholine, respectively. It increased lipid peroxidation, MPO levels and tissue collagen content of both aorta and heart samples. Taurine supplementation to nicotine‐treated animals reversed the contractile dysfunction and restored the endogenous GSH levels and decreased high lipid peroxidation and MPO activities in both tissues. These data suggest that taurine supplementation effectively attenuates the oxidative damage because of chronic nicotine administration possibly by its antioxidant effects.
Increased Infectious Disease Susceptibility Resulting from Outbreeding Depression
Authors: GOLDBERG TONY L. , GRANT EMILY C. , INENDINO KATE R. , KASSLER TODD W. , CLAUSSEN JULIE E. , PHILIPP DAVID P.
Published: March 2005

Abstract:  The mechanisms by which outbreeding depression leads to reduced fitness are poorly understood. We considered the hypothesis that outbreeding can depress fitness by increasing the susceptibility of hybrid individuals and populations to infectious disease. Competitive breeding trials in experimental ponds indicated that outbred largemouth bass ( Micropterus salmoides) crossed from two geographically and genetically distinct populations suffered a reduction in fitness of approximately 14% relative to parental stocks. We measured the comparative susceptibility of these same outbred stocks to a novel viral pathogen, largemouth bass virus. Following experimental inoculation, F2 generation hybrids suffered mortality at a rate 3.6 times higher than either F1 generation hybrids or wild‐type parental fish. Analysis of viral loads indicated that viral replication was more rapid in F2 fish than in F1 hybrids or wild‐type parental fish. We attribute these results to the disruption of coadapted gene complexes in the immune systems of outbred fish in the F2 generation. Increased susceptibility to infectious disease may be an important but underappreciated mechanism by which outbreeding reduces the fitness of individuals and populations and by which novel infectious diseases emerge in populations of hybrid organisms.
Physiological and Behavioral Differences in Magellanic Penguin Chicks in Undisturbed and Tourist‐Visited Locations of a Colony
Authors: WALKER BRIAN G. , BOERSMA P. DEE , WINGFIELD JOHN C.
Published: March 2005

Abstract:  Studies examining anthropogenic effects on wildlife typically focus on adults and on behavioral responses rather than the physiological consequences of human disturbances. Here we examined how Magellanic Penguin ( Spheniscus magellanicus) chicks living in either tourist‐visited or undisturbed areas of a breeding colony were affected by human visitation by comparing the baseline and stress‐induced levels of corticosterone during three periods of the breeding season. Newly hatched chicks in visited areas had higher corticosterone stress responses than newly hatched chicks in undisturbed areas (p =0.007), but baseline levels were similar (p =0.61). By 40–50 days of age and around fledging time, both visited and undisturbed chicks showed a robust corticosterone stress response to capture. Tourist‐visited chicks did not flee when approached by humans, however, whereas undisturbed chicks fled significantly sooner (i.e., when approached no closer than 9 m; p < 0.0001). Although it is unknown whether Magellanic Penguin chicks raised in visited areas suffer negative consequences from the elevation of the corticosterone stress response at hatching, they do exhibit behavioral habituation to human contact by the time they are ready to fledge. Unlike adults living in tourist areas, however, fledging chicks in visited areas do not have a decreased stress response to capture and restraint. Our results show that the coupling of behavioral and physiological habituation in Magellanic Penguins is complex and life‐history context may greatly affect the ability of wildlife to adapt to anthropogenic disturbances.
Predicting the Impact of Sea‐Level Rise on Caribbean Sea Turtle Nesting Habitat
Authors: FISH MARIANNE R. , CÔTÉ ISABELLE M. , GILL JENNIFER A. , JONES ANDREW P. , RENSHOFF SASKIA , WATKINSON ANDREW R.
Published: March 2005

Abstract:  The projected rise in sea level is likely to increase the vulnerability of coastal zones in the Caribbean, which are already under pressure from a combination of anthropogenic activities and natural processes. One of the major effects will be a loss of beach habitat, which provides nesting sites for endangered sea turtles. To assess the potential impacts of sea‐level rise on sea turtle nesting habitat, we used beach profile measurements of turtle nesting beaches on Bonaire, Netherlands Antilles, to develop elevation models of individual beaches in a geographic information system. These models were then used to quantify areas of beach vulnerable to three different scenarios of a rise in sea level. Physical characteristics of the beaches were also recorded and related to beach vulnerability, flooding, and nesting frequency. Beaches varied in physical characteristics and therefore in their vulnerability to flooding. Up to 32% of the total current beach area could be lost with a 0.5‐m rise in sea level, with lower, narrower beaches being the most vulnerable. Vulnerability varied with land use adjacent to the beach. These predictions about loss of nesting habitat have important implications for turtle populations in the region.
Relationship between Population Size and Fitness
Authors: REED DAVID H.
Published: March 2005

Abstract:  Long‐term effective population size, which determines rates of inbreeding, is correlated with population fitness. Fitness, in turn, influences population persistence. I synthesized data from the literature concerning the effects of population size on population fitness in natural populations of plants to determine how large populations must be to maintain levels of fitness that will provide adequate protection against environmental perturbations that can cause extinction. Integral to this comment on what has been done and what needs to be done, sThe evidence suggests that there is a linear relationship between log population size and population fitness over the range of population sizes examined. More importantly, populations will have to be maintained at sizes of >2000 individuals to maintain population fitness at levels compatible with the conservation goal of long‐term persistence. This approach to estimating minimum viable population size provides estimates that are in general agreement with those from numerous other studies and strengthens the argument that conservation efforts should ultimately aim at maintaining populations of several thousand individuals to ensure long‐term persistence.
Indigenous Uses, Population Density, and Conservation of Threatened Medicinal Plants in Protected Areas of the Indian Himalayas
Authors: KALA CHANDRA PRAKASH
Published: March 2005

Abstract:  For 10 years I monitored the population density of threatened medicinal plant species in seven protected areas in the Indian Himalayas. I also documented the indigenous uses of threatened medicinal plants through interviews with 138 herbal healers (83 Tibetan healers and 55 Ayurvedic healers) residing in the buffer zone villages of these protected areas. To assess the population status of threatened medicinal plant species, I sampled the 10 major habitat types in the protected areas. In all, I found 60 threatened medicinal plant species during the study period, of which 54 species occurred in the sampling plots. Twenty‐two percent of threatened medicinal plant species were critically endangered, 16% were endangered, and 27% were vulnerable. Thirty‐two threatened medicinal plant species were endemic to the Himalayan region. The density of threatened medicinal plant species varied with protected areas. The Valley of Flowers protected area had the highest number of threatened medicinal plant species. The “moist” habitat type was richest in these species among all 10 habitat types sampled. Arnebia euchroma (Royle ex Benth.) Johnston and Ephedra gerardiana Wall. ex Stapf. were the most common threatened medicinal plant species. The indigenous groups of healers used these threatened species in curing about 45 different ailments. Based on my findings, I believe that to ensure the long‐term sustainability of threatened medicinal plants, medicinal‐plant conservation areas should be established.
Characterization of depolarization and repolarization phases of mitochondrial membrane potential fluctuations induced by tetramethylrhodamine methyl ester photoactivation
Authors: Falchi Angela M. , Isola Raffaella , Diana Andrea , Putzolu Martina , Diaz Giacomo
Published: March 2005

Depolarization and repolarization phases (D and R phases, respectively) of mitochondrial potential fluctuations induced by photoactivation of the fluorescent probe tetramethylrhodamine methyl ester (TMRM) were analyzed separately and investigated using specific inhibitors and substrates. The frequency of R phases was significantly inhibited by oligomycin and aurovertin (mitochondrial ATP synthase inhibitors), rotenone (mitochondrial complex I inhibitor) and iodoacetic acid (inhibitor of the glycolytic enzyme glyceraldehyde‐3‐phosphate dehydrogenase). Succinic acid (mitochondrial complex II substrate, given in the permeable form of dimethyl ester) abolished the rotenone‐induced inhibition of R phases. Taken together, these findings indicate that the activity of both respiratory chain and ATP synthase were required for the recovery of the mitochondrial potential. The frequency of D phases prevailed over that of R phases in all experimental conditions, resulting in a progressive depolarization of mitochondria accompanied by NAD(P)H oxidation and Ca2+ influx. D phases were not blocked by cyclosporin A (inhibitor of the permeability transition pore) or o‐phenyl‐EGTA (a Ca2+ chelator), suggesting that the permeability transition pore was not involved in mitochondrial potential fluctuations.
Synthesis of β‐mannosides using the transglycosylation activity of endo‐β‐mannosidase from Lilium longiflorum
Authors: Sasaki Akiko , Ishimizu Takeshi , Geyer Rudolf , Hase Sumihiro
Published: March 2005

Endo‐β‐mannosidase is an endoglycosidase that hydrolyzes only the Manβ1‐4GlcNAc linkage of the core region of N‐linked sugar chains. Recently, endo‐β‐mannosidase was purified to homogeneity from Lilium longiflorum (Lily) flowers, its corresponding gene was cloned and important catalytic amino acid residues were identified [Ishimizu T., Sasaki A., Okutani S., Maeda M., Yamagishi M. & Hase S. (2004) J. Biol. Chem.279, 38555–38562]. In the presence of Manβ1‐4GlcNAcβ1‐4GlcNAc‐peptides as a donor substrate and p‐nitrophenyl β‐N‐acetylglucosaminide as an acceptor substrate, the enzyme transferred mannose to the acceptor substrate by a β1‐4‐linkage regio‐specifically and stereo‐specifically to give Manβ1‐4GlcNAcβ1‐pNP as a transfer product. Further studies indicated that not only p‐nitrophenyl β‐N‐acetylglucosaminide but also p‐nitrophenyl β‐glucoside and p‐nitrophenyl β‐mannoside worked as acceptor substrates, however, p‐nitrophenyl β‐N‐acetylgalactosaminide did not work, indicating that the configuration of the hydroxyl group at the C4 position of an acceptor is important. Besides mannose, oligomannoses were also transferred. In the presence of (Man)nManα1‐6Manβ1‐4GlcNAcβ1‐4GlcNAc‐peptides (n = 0–2) and pyridylamino GlcNAcβ1‐4GlcNAc, the enzyme transferred (Man)nManα1‐6Man en bloc to the acceptor substrate to produce pyridylamino (Man)nManα1‐6Manβ1‐4GlcNAcβ1‐4GlcNAc (n =0–2). Thus, the lily endo‐β‐mannosidase is useful for the enzymatic preparation of oligosaccharides containing the mannosyl β1,4‐structure, chemical preparations of which have been frequently reported to be difficult.
Oxidative folding of conotoxins sharing an identical disulfide bridging framework
Authors: Fuller Erika , Green Brad R. , Catlin Phil , Buczek Olga , Nielsen Jacob S. , Olivera Baldomero M. , Bulaj Grzegorz
Published: March 2005

Conotoxins are short, disulfide‐rich peptide neurotoxins produced in the venom of predatory marine cone snails. It is generally accepted that an estimated 100 000 unique conotoxins fall into only a handful of structural groups, based on their disulfide bridging frameworks. This unique molecular diversity poses a protein folding problem of relationships between hypervariability of amino acid sequences and mechanism(s) of oxidative folding. In this study, we present a comparative analysis of the folding properties of four conotoxins sharing an identical pattern of cysteine residues forming three disulfide bridges, but otherwise differing significantly in their primary amino acid sequence. Oxidative folding properties of M‐superfamily conotoxins GIIIA, PIIIA, SmIIIA and RIIIK varied with respect to kinetics and thermodynamics. Based on rates for establishing the steady‐state distribution of the folding species, two distinct folding mechanisms could be distinguished: first, rapid‐collapse folding characterized by very fast, but low‐yield accumulation of the correctly folded form; and second, slow‐rearrangement folding resulting in higher accumulation of the properly folded form via the reshuffling of disulfide bonds within folding intermediates. Effects of changing the folding conditions indicated that the rapid‐collapse and the slow‐rearrangement mechanisms were mainly determined by either repulsive electrostatic or productive noncovalent interactions, respectively. The differences in folding kinetics for these two mechanisms were minimized in the presence of protein disulfide isomerase. Taken together, folding properties of conotoxins from the M‐superfamily presented in this work and from the O‐superfamily published previously suggest that conotoxin sequence diversity is also reflected in their folding properties, and that sequence information rather than a cysteine pattern determines the in vitro folding mechanisms of conotoxins.
Characterization of HbpR binding by site‐directed mutagenesis of its DNA‐binding site and by deletion of the effector domain
Authors: Tropel David , van der Meer Jan R.
Published: March 2005

In the presence of 2‐hydroxybiphenyl, the enhancer binding protein, HbpR, activates the σ54‐dependent PhbpC promoter and controls the initial steps of 2‐hydroxybiphenyl degradation in Pseudomonas azelaica. In the activation process, an oligomeric HbpR complex of unknown subunit composition binds to an operator region containing two imperfect palindromic sequences. Here, the HbpR–DNA binding interactions were investigated by site‐directed mutagenesis of the operator region and by DNA‐binding assays using purified HbpR. Mutations that disrupted the twofold symmetry in the palindromes did not affect the binding affinity of HbpR, but various mutations along a 60 bp region, and also outside the direct palindromic sequences, decreased the binding affinity. Footprints of HbpR on mutant operator fragments showed that a partial loss of binding contacts occurs, suggesting that the binding of one HbpR ‘protomer’ in the oligomeric complex is impaired whilst leaving the other contacts intact. An HbpR variant, devoid of its N‐terminal sensing A‐domain, was unable to activate transcription from the hbpC promoter while maintaining protection of the operator DNA in footprints. Wild‐type HbpR was unable to activate transcription from the hbpC promoter when ΔA‐HbpR was expressed in the same cell, suggesting the formation of (repressing) hetero‐oligomers. This model implies that HbpR can self‐associate on its operator DNA without effector recognition or ATP binding. Furthermore, our findings suggest that the N‐terminal sensing domain of HbpR is needed to activate the central ATPase domain rather than to repress a constitutively active C domain, as is the case for the related regulatory protein XylR.
Glycolysis in Entamoeba histolytica
Authors: Saavedra Emma , Encalada Rusely , Pineda Erika , Jasso‐Chávez Ricardo , Moreno‐Sánchez Rafael
Published: March 2005

The synthesis of ATP in the human parasite Entamoeba histolytica is carried out solely by the glycolytic pathway. Little kinetic and structural information is available for most of the pathway enzymes. We report here the gene cloning, overexpression and purification of hexokinase, hexose‐6‐phosphate isomerase, inorganic pyrophosphate‐dependent phosphofructokinase, fructose‐1,6 bisphosphate aldolase (ALDO), triosephosphate isomerase, glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH), phosphoglycerate kinase, phosphoglycerate mutase (PGAM), enolase, and pyruvate phosphate dikinase (PPDK) enzymes from E. histolytica. Kinetic characterization of these 10 recombinant enzymes was made, establishing the kinetic constants at optimal and physiological pH values, analyzing the effect of activators and inhibitors, and investigating the storage stability and oligomeric state. Determination of the catalytic efficiencies at the pH optimum and at pH values that resemble those of the amoebal trophozoites was performed for each enzyme to identify possible controlling steps. This analysis suggested that PGAM, ALDO, GAPDH, and PPDK might be flux control steps, as they showed the lowest catalytic efficiencies. An in vitro reconstruction of the final stages of glycolysis was made to determine their flux control coefficients. Our results indicate that PGAM and PPDK exhibit high control coefficient values at physiological pH.
General Framework of Optimal Tool Trajectory Planning for Free-Form Surfaces in Surface Manufacturing
Authors: Chen Heping , Xi Ning , Sheng Weihua , Chen Yifan
Published: March 2005

Surface manufacturing is a process of adding material to or removing material from the surfaces of a part. Spray painting, spray forming, rapid tooling, spray coating, and polishing are some of the typical applications of surface manufacturing, where industrial robots are usually used. Tool planning for industrial robots in surface manufacturing is a challenging research topic. Typical teaching methods are not affordable any more because products are subject to a shorter product life, frequent design changes, small lot sizes, and small in-process inventory restrictions. An automatic tool trajectory planning process is hence desirable for tool trajectory planning of industrial robots. Based on the computer-aided design model of a part, the tool model, task constraints, and optimization criteria, a general framework of optimal tool trajectory planning in surface manufacturing is developed. Optimal tool trajectories are generated by approximately solving a multiobjective optimization problem. To test if the generated trajectory satisfies the given constraints, a trajectory verification model is developed. Simulations are performed to determine if the given constraints are satisfied. Simulation results show that the optimal tool trajectory planning framework can be applied to generate trajectories for a variety of applications in surface manufacturing. This general framework can also be extended to other applications such as dimensional inspection and demining.
Design Method of Die Geometry and Pass Schedule by Void Index in Multi-Pass Drawing
Authors: Kuboki Takashi , Abe Masaaki , Neishi Yutaka , Akiyama Masayoshi
Published: March 2005

The concept for die-geometry design is shown to suppress void growth in multi-pass drawing. First, the void index to evaluate the void fraction in multi-pass drawing was newly proposed based on the well-known equation to predict the fracture limit in cold working. Using finite element analysis, the influence of die geometries on the void index was investigated and it was clarified that the extra-low-angle die is effective whatever reduction in area is adopted. Moreover, dies were designed to have the effect of suppressing void with the minimum die length. A series of experiments was then carried out that successfully verified the numerical results.
On-the-Fly Substrate Eccentricity Recognition for Robotized Manufacturing Systems
Authors: Hosek Martin , Prochazka Jan
Published: March 2005

This paper describes a method for on-the-fly determination of eccentricity of a circular substrate, such as a silicon wafer in semiconductor manufacturing applications, carried by a robotic manipulator, where eccentricity refers to the difference between the actual location of the center of the substrate and its desired position on the end-effector of the robotic manipulator. The method utilizes a pair of external optical sensors located along the substrate transfer path. When moving a substrate along the transfer path, the robotic manipulator captures the positions and velocities of the end-effector at which the edges of the substrate are detected by the sensors. These data along with the expected radius of the substrate and the coordinates of the sensors are used to determine the eccentricity of the substrate. This information can be used by the robotic manipulator to compensate for eccentricity of the substrate when performing a place operation, resulting in the substrate being placed centered regardless of the amount and direction of the initial eccentricity. The method can also be employed to detect a defect, such as breakage, of a circular substrate and report an error condition which can abort or otherwise adjust operation of the robotic manipulator.
A Metric-Based Approach to Two-Dimensional (2D) Tool-Path Optimization for High-Speed Machining
Authors: Wang Hongcheng , Jang Peter , Stori James A.
Published: March 2005

Conventional tool-path generation strategies are readily available to generate geometrically feasible trajectories. Such approaches seldom take into consideration physical process concerns or dynamic system limitations. In the present work, an approach for improving a geometrically feasible tool-path trajectory based on quantifiable process metrics is developed. Two specific measures of toolpath quality are incorporated into the iterative improvement algorithm: instantaneous path curvature and instantaneous cutter engagement. These metrics are motivated by a desire to minimize acceleration requirements and maintain a stable steady-state cutting process during high-speed machining. The algorithm has been implemented for two-dimensional contiguous end-milling operations with flat end-mills, and case studies are presented to illustrate the approach.
Monitoring of Self-Tapping Screw Fastenings Using Artificial Neural Networks
Authors: Althoefer Kaspar , Lara Bruno , Seneviratne Lakmal D.
Published: March 2005

Screw fastenings account for a quarter of all assembly operations and automation of the process is highly desirable. This paper presents a novel strategy for monitoring this manufacturing process, focusing on the insertion of self-tapping screws. An artificial neural network (ANN), using “Torque-versus-Insertion-Depth” signature signals as input, is designed to distinguish between successful and failed insertions. The ANN is first tested using simulation data from an analytical model for screw insertions, and then validated using experimental torque signals obtained from an electric screwdriver. The results demonstrate that ANNs can effectively monitor the screw fastening process and cope with a wide range of insertion cases interpolating for unseen insertion signals.
Area-Selective Adhesive Bonding Using Photosensitive BCB for WL CSP Applications
Authors: Polyakov A. , Bartek M. , Burghartz J. N.
Published: March 2005

This paper reports on an area-selective adhesive wafer bonding, using photosensitive BCB from Dow Co. The strength of the fabricated bonds is characterized using the wedge-opening and tensile methods. The measured fracture toughness is 53.5±3.9J/m2 with tensile strength up to 71 MPa. The potential application of BCB bonding is demonstrated on a concept of wafer-level chip-scale package for RF applications and microfilter array for microfluidic applications.
Optical Fiber Shifts and Shear Stains in V-Groove Arrays for Optical MEMS Packaging
Authors: Zhong Z. W. , Lim S. C. , Asundi A.
Published: March 2005

The objective of this study is to investigate optical fiber shifts and shear stains in V-groove arrays for optical microelectromechanical system packaging, when the arrays are subjected to temperature cycling. Thermally induced optical fiber shifts in the joints consisting of an optical fiber, epoxy adhesive, and silicon substrate were simulated using a finite element analysis (FEA) package ANSYS. Experiments using real-time Moire´ interferometry were also performed at temperatures of 25, 40, 60, 85 and 100°C for confirmation of the analysis results. The study revealed that thermally induced fiber shifts increased with the number of V-groove channels. The shear strains at the fiber and silicon interface in the fiber joints increased as the V-groove channel was further away from the neutral point of the fiber array packages. The optical coupling loss is the greatest during thermal loading for the outer fiber in the four channel V-groove array. Optical loss of 0.334 and 0.346 dB was calculated using the fiber shift values obtained from the FEA and experimental results, respectively. The effect of fiber shifts, especially the shift of the fiber that is positioned at the outermost V-groove in the array, cannot be ignored.
Investigation of Conductive Adhesive Bonding Using UV Curable Anisotropic Conductive Adhesives at Different Curing Conditions
Authors: Lee K. K. , Tan S. C. , Chan Y. C.
Published: March 2005

Generally, adhesive materials can be cured in a short time under high curing temperature. High curing temperature usually leads to an increase in cross-link density and a homologous increase in heat resistance. Nevertheless, curing process under high temperature problems can occur such as the inclination for the adhesive materials to shrinkage, cracks, voids and it would probably lower the dielectric properties. UV curing of anisotropic conductive adhesives (ACAs) offers several advantages over the conventional epoxy resin, including rapid cure, little to no emission of volatile organic compounds and without affecting other components in the assembly [Pataki, W. S., 1997, “Optimization of Free-Radical Initiation Reactions in the Electrical Industry,” Electrical Insulation Conference and Electrical Manufacturing and Coil Winding Conference Proceedings, pp. 745–751]. Based on the aforementioned advantages, it is worth investigating the bonding properties at different curing conditions. In this work, a new type of UV curable ACA for chip-on-flex application is presented. The adhesive bonds of the chip-on-flex application are cured at different cure cycles within a range of UV frequencies. Cure cycles in this work were the different periods of time that were needed to cure the ACAs under different UV light intensities. Fourier transform infrared spectroscopy with attenuated total internal reflection was used to investigate the curing degree of the ACAs at different cure cycles. The result shows that the longer the curing time and the larger the UV intensity, the higher the curing degree can be obtained. Furthermore, the curing time in the UV curable ACA was much shorter than that of the conventional thermal curable ACAs. Shear test was done to find out the shear strength of the bonding. Finally, after shear test, scanning electron microscope was used to investigate the fracture mode of the chip-on-flex application at different curing cycles.
Numerical Analysis of High-Speed Bodies in Partially Cavitating Axisymmetric Flow
Authors: Varghese Abraham N. , Uhlman James S. , Kirschner Ivan N.
Published: March 2005

Partial cavitation of high-speed axisymmetric bodies is modeled using a steady potential-flow boundary-element technique. The effects of several key parameters defining the vehicle geometry are examined for configurations consisting of a disk cavitator followed by a conical section and ending in a cylindrical body. A single cavity is assumed to detach at the edge of the disk. A variety of conditions have been studied, including cavity closure on either the conical or cylindrical portions of the vehicle, variations in the cone angle, and variations in the radius of the cylindrical section. The results for the partially cavitating case are also compared with those for the supercavitating case.
Self-Excited Oscillations of Flow Past a Perforated Plate: Attenuation Via Three-Dimensional Surface Elements
Authors: Ozalp C. , Pinarbasi A. , Rockwell D.
Published: March 2005

It is known that flow past a perforated plate can give rise to purely hydrodynamic, self-sustained oscillations, which have a wavelength of the order of the plate length. The present investigation demonstrates that these oscillations can be effectively attenuated by three-dimensional surface elements in the form of vortex generators. A technique of high-image-density particle image velocimetry is employed to characterize the patterns immediately adjacent to the surface of the perforated plate. These patterns are interpreted in conjunction with pressure spectra at the trailing-end of the plate, as well as velocity spectra determined from cinema sequences of images. In the absence of the three-dimensional surface elements, a well-defined front of the unstable oscillation propagates along the surface of the plate. In the presence of an appropriate surface element, the front is no longer detectable, and instantaneous and averaged defects of the streamwise velocity and surface-normal vorticity exist along the span of the plate. The magnitudes and spanwise wavelengths of these defects are directly related to the extent of attenuation of the oscillation. Since the magnitudes of these defects decay significantly with distance along the plate, the most effective attenuation typically occurs for plate lengths less than or equal to a critical length. An appropriate measure of the degree of attenuation is a reduction in the magnitude of the coherent component of the fluctuating pressure. For all cases, even in the presence of effective attenuation, a low magnitude spectral peak at the frequency of the inherent oscillation is still discernible; it may be either sharp or broadband, and is indicative of the robust nature of the self-sustained oscillation.
Fundamental Analysis of the Secondary Flows and Jet-Wake in a Torque Converter Pump—Part I: Model and Flow in a Rotating Passage
Authors: Flack R. , Brun K.
Published: March 2005

Previously, experimental results for the velocity field in a torque converter pump showed strong jet/wake characteristics including backflows and circulatory secondary flows. To understand the fundamental flow behavior simplified analytical/numerical Navier-Stokes flow models were developed herein to independently analyze the pump pressure-to-suction side jet/wake flow, the core-to-shell side jet/wake flow, and the secondary flows. Parametric studies were undertaken to evaluate the effect that operating conditions and geometry had on the characteristics. Two relatively simple models were employed: (i) a rotating two-dimensional straight-walled duct to model the pressure-to-suction side jet/wake flow due to rotational Coriolis forces and (ii) a 180 deg flow bend to model the core-to-shell side jet/wake flow due to rapid radial/axial flow turning. The formation and development of the pump jet/wake flow was studied in detail. Results showed that the suction side wake, which was due to the counter-rotational tangential Coriolis force, was almost only a function of the modified Rossby number and independent of the Reynolds number. Increasing the modified Rossby number increased the pressure-to-suction side jet/wake flow. A geometric parameter that was seen to affect the pump flow was the backsweeping angle for the pressure-to-suction side jet/wake. Results showed that using backswept blades can completely eliminate the pressure-to-suction side jet/wake flow effect. Other geometrical parameters were tested but only a small to moderate influence on the jet/wake flow phenomena was found. Predicted trends compared favorably with experimental results.