bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functional morphology of venous structures associated with the male and female reproductive systems in Florida manatees (Trichechus manatus latirostris)†
Authors: Rommel Sentiel A. , Pabst D. Ann , McLellan William A. 
Published: August 2002

AbstractThe reproductive organs of Florida manatees (Trichechus manatus latirostris) are surrounded by thermogenic locomotory muscles and insulating fat. Manatees are reported to maintain core body temperatures of 35.6°–36.4° C, temperatures known to interfere with production and maturation of viable sperm in terrestrial mammals. We describe two novel venous plexuses associated with the manatee epididymis. Each epididymis is located in a hypogastric fossa at the caudolateral extremity of the abdominal cavity. Each hypogastric fossa is lined by an inguinal venous plexus that receives cooled blood from a superficial thoracocaudal plexus. We conclude that male manatees may prevent hyperthermic insult to their reproductive tissues by feeding cooled superficial blood to venous plexuses deep within their bodies. Female manatees also possess hypogastric fossae and venous structures similar to those found in male manatees. The ovaries, uterine tubes, and distal tips of the uterine horns are located in the hypogastric fossae. We suggest that the thermovascular structures we describe also prevent hypothermic insult to female manatee reproductive tissues. The venous structures in manatees are functionally similar to structures associated with reproductive thermoregulation in cetaceans and phocid seals. Thus, these thermovascular structures appear to be convergent morphological adaptations that occur in three clades of diving mammals with independent evolutionary histories. Anat Rec 264:339–347, 2001. Published 2001 Wiley‐Liss, Inc.
Bone density of the human talus does not increase with the cartilage degeneration score
Authors: Muehleman C. , Berzins A. , Koepp H. , Eger W. , Cole A.A. , Kuettner K.E. , Sumner D.R. 
Published: August 2002

AbstractOsteoarthritis (OA) is a common, disabling condition of synovial joints that can eventually lead to reduced, or lost, mobility. It is characterized by both articular cartilage degeneration and subchondral bone changes. However, a cause‐and‐effect relationship between the two tissues remains controversial. Increased subchondral bone density has been associated with early degenerative changes in the cartilage of knee, hip, and finger joints—joints in which progressive changes to OA are common. In contrast, the ankle joint is known to exhibit early cartilage changes, but is not prone to the development of OA. In the present study, it was found that cartilage degeneration on the talus is not associated with an increase in bone density, as assessed through peripheral quantitative computed tomography (pQCT). Anat Rec 266:81–86, 2002. © 2002 Wiley‐Liss, Inc.
Immunolocalization of vacuolar‐type H+‐ATPase, cathepsin K, matrix metalloproteinase‐9, and receptor activator of NFkB ligand in odontoclasts during physiological root resorption of human deciduous teeth
Authors: Oshiro Takahiro , Shibasaki Yoshinobu , Martin T. John , Sasaki Takahisa 
Published: August 2002

AbstractTo investigate the cellular mechanisms of physiological root resorption in human deciduous teeth, the authors examined the immunocytochemical localization of vacuolar‐type H+‐ATPase, a lysosomal cysteine proteinase, cathepsin K, matrix metalloproteinase‐9 (MMP‐9), and receptor activator of NFKB ligand (RANKL) in odontoclasts. H+‐ATPase, cathepsin K, and MMP‐9 are the most important enzymes for decalcification of apatite crystals and degradation of type‐I collagen. In addition, RANKL is one of the key regulatory molecules in osteoclast formation and functions. Odontoclasts developed extensive ruffled borders and clear zones apposed to the resorbing root dentine surfaces. On immunoelectron microscopy, the expression of vacuolar‐type H+‐ATPase was detected along the limiting membranes of pale vacuoles and the ruffled border membranes of odontoclasts. Cathepsin K in odontoclasts was localized within pale vacuoles, lysosomes, the extracellular canals of ruffled borders, and the underlying resorbing dentine surfaces. MMP‐9 localization in odontoclasts was similar to those of cathepsin K. RANKL was detected in both mononuclear stromal cells and odontoclasts located on resorbing dentine surfaces. These results suggest that (1) odontoclasts are directly involved in decalcification of apatite crystals by active extrusion of proton ions mediated by H+‐ATPase and (2) extracellular degradation of dentine type‐I collagen by both cathepsin K and MMP‐9, and (3) odontoclast differentiation and activity are regulated, at least in part, by RANKL, possibly produced by mononuclear stromal cells and odontoclasts themselves in the resorbing tissues. Thus, the cellular mechanisms of physiological root resorption appear to be quite similar to those of osteoclastic bone resorption. Anat Rec 264:305–311, 2001. © 2001 Wiley‐Liss, Inc.
The X—a sexy chromosome
Authors: Graves Jennifer A. Marshall , Delbridge Margaret L. 
Published: August 2002

AbstractThere is new and convincing evidence(1) that the mammalian X chromosome, as well as the Y chromosome, contains an atypically high proportion of genes involved in sex and reproduction (SRR genes). Here we consider alternative explanations for this concentration. One possibility is that a particularly well‐endowed autosome was “chosen” for a career as a sex chromosome. Alternatively, the high concentration of SRR genes may have resulted from the accumulation of these genes on the X after the degradation of the Y, either by transposition of autosomal SRR genes to a “selfish X”, or by acquisition of SRR functions by widely expressed genes on the X. We suggest experiments to distinguish these possibilities, and speculate on the implications of gathering evidence that genes with other functions, too, are not distributed uniformly over the genome. BioEssays 23:1091–1094, 2001. © 2001 John Wiley & Sons, Inc.
Gleanings of a chemiosmotic eye
Authors: Harold Franklin M. 
Published: August 2002

AbstractIn 1961, an inventive Englishman, named Peter Mitchell, proposed a radically novel hypothesis to explain how energy is conserved during respiration and photosynthesis, and applied to the generation of ATP and other kinds of functional work. The chemiosmotic hypothesis sparked an intense controversy that lasted for 15 years. Today, Mitchell's conception of proton currents and their role in phosphorylation and active transport is generally accepted, and has ramified into many corners of cellular physiology. His most profound contribution may have been to introduce spatial direction into biochemistry, and thereby transform our perception of the relationship between molecules and cells. BioEssays 23:848–855, 2001. © 2001 John Wiley & Sons, Inc.
The association between a negatively charged ligand and the electronegative binding pocket of its receptor
Authors: Huang Hung‐Chung , Briggs James M. 
Published: August 2002

AbstractMany examples exist of charged amino acids that play a role in attracting or holding a charged ligand toward or inside an oppositely charged binding pocket of the protein. For example, the enzymes superoxide dismutase, triose‐phosphate isomerase, and acetylcholinesterase can steer ligands toward their oppositely charged binding pockets or gorges. Interestingly, in our Brownian dynamics simulations of a phosphate‐binding protein, we discovered that negatively charged phosphate (HPO) could make its way into the negatively charged binding pocket. In fact, the phosphate‐binding protein exhibits counterintuitive kinetics of association. That is, one would expect that the rate of association would increase on increases to the ionic strength since the interaction between the ligand, with a charge of −2, and the electronegative binding pocket would be repulsive and greater screening should reduce this repulsion and increase the rate of association. However, the opposite is seen—i.e., the rate of association decreases on increases in the ionic strength. We used Brownian dynamics techniques to compute the diffusion limited association rate constants between the negatively charged phosphate ligand and several open forms of PBP (wild‐type and several mutants based on an x‐ray structure of open‐form PBP, mutant T141D). With the appropriate choices of reaction criteria and molecular parameters, the ligand was able to diffuse into the binding pocket. A number of residues influence binding of the ligand within the pocket via hydrogen bonds or salt bridges. Arg135 partially neutralizes the charges on the HPO ligand in the binding pocket, allowing it to enter. It is also found that the positive electrostatic patches above and below the binding entrance of PBP contribute the major attractive forces that direct the ligand toward the surface of the protein near the binding site. © 2002 Wiley Periodicals, Inc. Biopolymers 63: 247–260, 2002; DOI 10.1002/bip.10050
High resolution NMR analysis of the seven transmembrane domains of a heptahelical receptor in organic‐aqueous medium
Authors: Arshava Boris , Taran Irina , Xie Haibo , Becker Jeffrey M. , Naider Fred 
Published: August 2002

AbstractThe NMR properties of seven peptides representing the transmembrane domains of the α‐factor receptor from Saccharomyces cerevisiae were examined in trifluoroethanol/water (4:1) at 10 to 55°C. The parameters extracted indicated all peptides were helical in this membrane mimetic solvent. Using chemical shift indices as the criterion, helicity varied from 64 to 83%. The helical residues in the peptides corresponded to the region predicted to cross the hydrocarbon interior of the bilayer. A study of a truncated 25‐residue peptide corresponding to domain 2 gave evidence that the helix extended all the way to the N‐terminus of this peptide, indicating that sequence and not chain end effects are very important in helix termination for our model peptides. Both nuclear Overhauser effect spectroscopy (NOESY) connectivities and chemical shift indices revealed significant perturbations around prolyl residues in the helices formed by transmembrane domains 6 and 7. Molecular models of the transmembrane domains indicate that helices for domains 6 and 7 are severely kinked at these prolyl residues. The helix perturbation around proline 258 in transmembrane domain 6 correlates with mutations that cause phenotypic changes in this receptor. © 2002 Wiley Periodicals, Inc. Biopolymers 64: 161–176, 2002
Enzymatic coupling of phenol vapors onto chitosan
Authors: Wu Li‐Qun , Chen Tianhong , Wallace Kimberlee K. , Vazquez‐Duhalt Rafael , Payne Gregory F. 
Published: August 2002

AbstractPhenols are important industrial chemicals, and because they can be volatile, also appear as air pollutants. We examined the potential of tyrosinase to react with the volatile phenol p‐cresol. Three lines of evidence support the conclusion that volatile phenols react with tyrosinase and are coupled (i.e., chemisorbed) onto chitosan films. First, phenol‐trapping studies indicated that p‐cresol can be removed from vapors if the vapors are contacted with tyrosinase‐coated chitosan films. Second, the ultraviolet absorbance of tyrosinase‐coated chitosan films changes dramatically when they are contacted with cresol‐containing vapors, whereas control films are unaffected by contacting with cresol vapors. Third, pressure measurements indicate that tyrosinase‐coated chitosan films only react with cresol vapors if the oxygen cosubstrate is present. Additional studies demonstrate the potential of tyrosinase‐coated chitosan films/membranes for the detection and removal of phenol vapors. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 76: 325–332, 2001.
Transformation of phosphorus and relevant intracellular compounds by a phosphorus‐accumulating enrichment culture in the presence of both the electron acceptor and electron donor
Authors: Ahn Johwan , Daidou Tomotaka , Tsuneda Satoshi , Hirata Akira 
Published: August 2002

AbstractThis study was conducted to obtain a better insight into the metabolic behavior of denitrifying phosphate‐accumulating organisms relative to the transformations of relevant intracellular compounds as well as phosphorus and nitrate for enhanced biological phosphorus removal under different combinations of electron acceptor (oxygen or nitrate) and electron donor (acetate). Under anoxic conditions, the amount of polyhydroxybutyrate (PHB) produced per acetate taken up considerably increased with the increasing amount of nitrate reduced whereas the amounts of nitrate reduced and phosphorus released per acetate taken up remained almost constant. However, glycogen utilization occurred during PHB production and then was again observed in response to the initial supplementation of acetate after glycogen accumulation was transiently observed during anoxic phosphorus uptake using nitrate as an electron acceptor. On the other hand, under subsequent aerobic conditions, the additional supplementation of acetate again caused aerobic phosphorus release and PHB production, which showed that PHB production was associated with polyphosphate cleavage regardless of electron acceptor conditions. In contrast to anoxic conditions, glycogen accumulation was observed during PHB production. Based on these observations, the preliminary model for the metabolic behavior of denitrifying phosphate‐accumulating organisms was proposed and could well account for the complex transformations of PHB and glycogen together with phosphorus release in the presence of acetate under different electron acceptors. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 79: 83–93, 2002.
On‐column deracemization of an atropisomeric biphenyl by quinine‐based stationary phase and determination of rotational energy barrier by enantioselective stopped‐flow HPLC and CEC
Authors: Tobler Ernst , Lämmerhofer Michael , Mancini Giovanna , Lindner Wolfgang 
Published: August 2002

AbstractThe reversible enantiomerization of axially chiral 2′‐dodecyloxy‐6‐nitrobiphenyl‐2‐carboxylic acid was studied in the presence of a brush type chiral stationary phase based on O‐(tert‐butylcarbamoyl) quinine as chiral selector unit by stopped‐flow high‐performance liquid chromatography (sfHPLC) and capillary electrochromatography (sfCEC). After initial separation of the enantiomers in the first section of the column, the flow was stopped and the resolved species allowed to enantiomerize on‐column. From this conversion, which could be determined from the enantiomeric ratios at different enantiomerization times, kinetic rate constants were calculated. By sfHPLC at a constant temperature of 15°C, kinetic rate constants in the presence of the CSP were found to be 4.1 × 10−5s−1and 2.2 × 10−5s−1for the (−) and (+)‐enantiomers, respectively, corresponding to half‐lives of 279 and 530 min. Thus, apparent activation energies of enantiomerization were calculated to be 93.0 and 94.6 kJ mol−1for the (−) and (+)‐enantiomers. On the macroscopic level, the apparent difference of rotational energy barriers and kinetic rate constants for both enantiomers is reflected as deracemization. For example, starting from a racemic mixture, an enantiomeric excess (ee) of 14% was seen in the stopped‐flow HPLC experiment described after an enantiomerization time of 220 min at 15°C, and a maximal ee of 17% can be approximated after infinite enantiomerization time. There is good agreement between HPLC and CEC results as well as their experimental errors, confirming that the new sfCEC technique may be a valuable and convenient tool to study interconversion processes. Chirality 13:641–647, 2001. © 2001 Wiley‐Liss, Inc.
Enantiodiscrimination of chiral α‐aminophosphonic acids by mass spectrometry
Authors: Paladini A. , Calcagni C. , Di Palma T. , Speranza M. , Laganà A. , Fago G. , Filippi A. , Satta M. , Giardini Guidoni A. 
Published: August 2002

AbstractDiastereomeric clusters between first‐group metal ions (M+) and chiral α‐aminophosphonic acids (A and B) have been readily generated in the gas phase by electrospray ionization (ESI) and their fragmentation investigated by mass spectrometry. The complexes studied had the general formula [MASB2]+ and [MARB2]+, where M = H, Li, Na, or K, AS and AR are the two enantiomers of a given acid A, and B is a reference α‐aminophosphonic acid of defined configuration. Collision‐induced decomposition (CID) of [MASB2]+ and [MARB2]+ leads to fragmentation patterns characterized by [MAB]+/[MB2] abundance ratios which depend on the configuration of ligand A. These different spectral features were correlated to the different stability of the diastereomeric [MASB2]+ and [MARB2]+ complexes in the gas phase. The results have been discussed in the light of MM2 Molecular Mechanics Force Field calculations. Chirality 13:707–711, 2001. © 2001 Wiley‐Liss, Inc.
Enantioseparation properties of (1→6)‐α‐D‐glucopyranan and (1→6)‐α‐D‐mannopyranan tris(phenylcarbamate)s as chiral stationary phases in HPLC
Authors: Kusuno Atsushi , Mori Manami , Satoh Toshifumi , Miura Masakatsu , Kaga Harumi , Kakuchi Toyoji 
Published: August 2002

AbstractSynthetic polysaccharides, (1→6)‐α‐D‐glucopyranan (3a) and (1→6)‐α‐D‐mannopyranan (3b), were prepared by the cationic ring‐opening polymerization of 1,6‐anhydro‐2,3,4‐tri‐O‐allyl‐β‐D‐glucopyranose (1a) and 1,6‐anhydro‐2,3,4‐O‐6‐allyl‐β‐D‐mannopyranose (1b), followed by the cleavage of the allyl ether linkage of 2,3,4‐tri‐O‐allyl‐(1→6)‐α‐D‐glucopyranan (2a) and 2,3,4‐tri‐O‐allyl‐(1→6)‐α‐D‐mannopyranan (2b), respectively. 2,3,4‐Tris‐O‐(3,5‐dimethylphenylcarbamoyl)‐ and 2,3,4‐tris‐O‐(3,5‐dichlorophenylcarbamoyl)‐(1→6)‐α‐D‐glucopyranan (CSP‐1 and CSP‐2, respectively) and 2,3,4‐tris‐O‐(3,5‐dimethylphenylcarbamoyl)‐ and 2,3,4‐tris‐O‐(3,5‐dichlorophenylcarbamoyl)‐(1→6)‐α‐D‐mannopyranan (CSP‐3 and CSP‐4, respectively) were prepared by the reaction of 3 with the corresponding 3,5‐disubstituted phenylisocyanates and the chiral recognition abilities of CSP‐1–4 as chiral stationary phases (CSPs) in high‐performance liquid chromatography (HPLC) were evaluated. Racemic compounds such as trans‐cyclopropanedicarboxylic acid dianilide (9), 1,2,2,2‐tetraphenylethanol (10), flavanone (11), Tröger's base (12), benzoin (13), and cobalt(III) tris(acetylacetonate) (14) were efficiently resolved using CSP‐1–4. For comparison among CSPs, the chiral recognition properties of the (1→6)‐α‐D‐glucopyranan CSPs were different from that of the (1→6)‐α‐D‐mannopyranan CSPs, and CSP‐4 exhibited the highest chiral recognition ability among the CSPs. The resolution factors of 12 and 14 were 0.42 and 0.56 for CSP‐1, 0.32 and 2.16 for CSP‐2, 1.80 and 0.84 for CSP‐3, and 2.31 and 8.26 for CSP‐4, respectively. Chirality 14:498–502, 2002. © 2002 Wiley‐Liss, Inc.
Post‐karyokinesis centrosome movement leaves a trail of unanswered questions
Authors: Ou Young Y. , Rattner Jerome B. 
Published: August 2002

AbstractThe centrosome is a complex structure composed of a large number of proteins (pericentriolar material, PCM) usually organized around a pair of centrioles (or a centriole duplex). This structure is capable of nucleating and organizing microtubules, duplication, and motility. In general, episodes of dramatic centrosome movement correlate with periods of cellular reorganization and nowhere is cellular reorganization more apparent, or more important, than in the periods before and after cell division. It is now clear that centrosome movement occurs not only prior to cell division but also at its completion, in concert with cytokinesis. The focus of this review is the newly emerging picture of centrosome activity during the post‐karyokinesis period and the role that this activity might play in the transition of cells from mitosis to interphase. Cell Motil. Cytoskeleton 51:123–132, 2002. © 2002 Wiley‐Liss, Inc.
Simultaneous quantification of cell motility and protein‐membrane‐association using active contours
Authors: Dormann Dirk , Libotte Thorsten , Weijer Cornelis J. , Bretschneider Till 
Published: August 2002

AbstractWe present a new method for the quantification of dynamic changes in fluorescence intensities at the cell membrane of moving cells. It is based on an active contour method for cell‐edge detection, which allows tracking of changes in cell shape and position. Fluorescence intensities at specific cortical subregions can be followed in space and time and correlated with cell motility. The translocation of two GFP tagged proteins (CRAC and GRP1) from the cytosol to the membrane in response to stimulation with the chemoattractant cAMP during chemotaxis of Dictyostelium cells and studies of the spatio‐temporal dynamics of this process exemplify the method: We show that the translocation can be correlated with motility parameters and that quantitative differences in the rate of association and dissociation from the membrane can be observed for the two PH domain containing proteins. The analysis of periodic CRAC translocation to the leading edge of a cell responding to natural cAMP waves in a mound demonstrates the power of this approach. It is not only capable of tracking the outline of cells within aggregates in front of a noisy background, but furthermore allows the construction of spatio‐temporal polar plots, capturing the dynamics of the protein distribution at the cell membrane within the cells' moving co‐ordinate system. Compilation of data by means of normalised polar plots is suggested as a future tool, which promises the so‐far impossible practicability of extensive statistical studies and automated comparison of complex spatio‐temporal protein distribution patterns. Cell Motil. Cytoskeleton 52:221–230, 2002. © 2002 Wiley‐Liss, Inc.
Thermal activation of single kinesin molecules with temperature pulse microscopy
Authors: Kawaguchi Kenji , Ishiwata Shin'ichi 
Published: August 2002

AbstractConventional kinesin is a processive motor protein that keeps “walking” along a microtubule using chemical energy released by ATP hydrolysis. We previously studied the effects of temperature between 15° and 35°C on the moving velocity, force, and processivity of single kinesin molecules using a bead assay [Kawaguchi and Ishiwata, 2000b: Biochem Biophys Res Commun 272:895–899]. However, we could not examine the effects of temperature higher than 35°C because of the thermal damage to proteins. Here, using temperature pulse microscopy (TPM) [Kato et al., 1999: Proc Natl Acad Sci USA 96:9602–9606], we could examine the temperature dependence of the gliding velocity of single kinesin molecules interacting with a microtubule above 35°C up to 50°C (instantaneously, ∼60°C), where the velocity reached 3.68 μm/s, the highest ever reported. The Arrhenius plot showed no breaks between 15° and 50°C with a unique activation energy of about 50 kJ/mol, suggesting that the molecular mechanism of kinesin motility is common over a broad temperature range including physiological temperature. Cell Motil. Cytoskeleton 49:41–47, 2001. © 2001 Wiley‐Liss, Inc.