bluuebunny/crossref_metadata_2025 huggingface dataset:
Examination of genetic linkage of chromosome 15 to schizophrenia in a large Veterans Affairs Cooperative Study sample*
Authors: Tsuang Debby W. , Skol Andrew D. , Faraone Stephen V. , Bingham Stephen , Young Keith A. , Prabhudesai Sarita , Haverstock Susan L. , Mena Felicitas , Menon A. Shrikumar , Bisset Darren , Pepple John , Sauter Fred , Baldwin Charlene , Weiss David , Collins Joseph , Boehnke Michael , Schellenberg Gerard D. , Tsuang Ming T.
Published: October 2004

Previous studies have reported genetic linkage evidence for a schizophrenia gene on chromosome 15q. Here, chromosome 15 was examined by genetic linkage analysis using 166 schizophrenia families, each with two or more affected subjects. The families, assembled from multiple centers by the Department of Veterans Affairs Cooperative Study Program, consisted of 392 sampled affected subjects and 216 affected sibling pairs. By DSM‐III‐R criteria, 360 subjects (91.8%) had a diagnosis of schizophrenia and 32 (8.2%) were classified as schizo‐affective disorder, depressed. Participating families had diverse ethnic backgrounds. The largest single group were northern European American families (n = 62, 37%), but a substantial proportion was African American kindreds (n = 60, 36%). The chromosome 15 markers tested were spaced at intervals of approximately 10 cM over the entire chromosome and 2–5 cM for the region surrounding the α‐7 nicotinic cholinergic receptor subunit gene (CHRNA7). These markers were genotyped and the data analyzed using semiparametric affecteds‐only linkage analysis. In the European American families, there was a maximum Z‐score of 1.65 between markers D15S165 and D15S1010. These markers are within 1 cM from CHRNA‐7, the site previously implicated in schizophrenia. However, there was no evidence for linkage to this region in the African America kindreds. © 2001 Wiley‐Liss, Inc.
Reactive processing and properties of styrene–maleic anhydride and poly(tetramethylene ether glycol)
Authors: Bayram G. , Yilmazer U.
Published: October 2004

The anhydride/hydroxyl‐functionalized blends of styrene–maleic anhydride (SMAH) with poly(tetramethylene ether glycol) (PTMEG) in the presence or absence of a hydrated zinc acetate catalyst were produced in a batch mixer and in a corotating twin‐screw extruder. In batch mixing, torque values increased with time as a result of chain‐extension/branching reactions. The reaction products were studied by thermal, mechanical, morphological, and spectroscopic characterization techniques. The glass transition temperature of SMAH was lowered by the addition of PTMEG into the system. Major morphological changes were observed at the initial stages of extrusion. The changes in the screw speed influenced the mechanical properties and morphology of the blends. SMAH/PTMEG blends were brittle due to the glassy nature of SMAH. FTIR analysis of the SMAH/PTMEG system showed carboxylic acid and ester formation in the extrusion experiments. Mechanical property data and FTIR spectra indicated that at 150 rpm chain‐extension/branching reactions were maximized due to ester formation. However, at 220 rpm, a lower extent of ester formation was observed due to the lower residence time in the extruder. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2148–2156, 2002
Thermosetting polyurethanes with water‐swollen and shape memory properties
Authors: Chen Wei , Zhu Chengye , Gu Xuerong
Published: October 2004

A series of shape memory polyurethanes (SPU) with different component ratio of PEG, MDI, BDO, and crosslinker DEA were synthesized by stepwise polymerization in DMF. WAXD, SAXS, DMTA, and DTA were used to study the microphase structure of SPU. No obvious phase‐separation and crystalline evidence of the PEG soft segment and hard segment were obtained in this work. The water‐swollen ratio increases with both the increasing molecular weight of PEG soft segment and the decreasing density of the chemical crossbonding. All the samples show good thermally stimulated shape memory properties. When the molar ratio of soft segment to hard segment is close, the shape recovery time reduces along with the increasing density of the chemical crossbonding. When the densities of the chemical crossbonding are similar, the shape recovery time reduces with the increasing molecular weight of the PEG soft segment. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1504–1512, 2002; DOI 10.1002/app.10357
Enhanced fracture toughness of epoxy resins with novel amine‐terminated poly(arylene ether sulfone)–carboxylic‐terminated butadiene‐acrylonitrile–poly(arylene ether sulfone) triblock copolymers
Authors: Kim H. R. , Myung B. Y. , Yoon T. H. , Song K. H.
Published: October 2004

Amine‐terminated poly(arylene ether sulfone)–carboxylic‐terminated butadiene‐acrylonitrile–poly(arylene ether sulfone) (PES‐CTBN‐PES) triblock copolymers with controlled molecular weights of 15,000 (15K) or 20,000 (20K) g/mol were synthesized from amine‐terminated PES oligomer and commercial CTBN rubber (CTBN 1300x13). The copolymers were utilized to modify a diglycidyl ether of bisphenol A epoxy resin by varying the loading from 5 to 40 wt %. The epoxy resins were cured with 4,4′‐diaminodiphenylsulfone and subjected to tests for thermal properties, plane strain fracture toughness (KIC), flexural properties, and solvent resistance measurements. The fracture surfaces were analyzed with SEM to elucidate the toughening mechanism. The properties of copolymer‐toughened epoxy resins were compared to those of samples modified by PES/CTBN blends, PES oligomer, or CTBN. The PES‐CTBN‐PES copolymer (20K) showed a KIC of 2.33 MPa m0.5 at 40 wt % loading while maintaining good flexural properties and chemical resistance. However, the epoxy resin modified with a CTBN/8K PES blend (2:1) exhibited lower KIC (1.82 MPa m0.5), lower flexural properties, and poorer thermal properties and solvent resistance compared to the 20K PES‐CTBN‐PES copolymer‐toughened samples. The high fracture toughness with the PES‐CTBN‐PES copolymer is believed to be due to the ductile fracture of the continuous PES‐rich phases, as well as the cavitation of the rubber‐rich phases. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1556–1565, 2002; DOI 10.1002/app.10390
Elaboration of ion‐exchange membranes with semi‐interpenetrating polymer networks containing poly(vinyl alcohol) as polymer matrix
Authors: Lebrun L. , Da Silva E. , Metayer M.
Published: October 2004

Ion‐exchange membranes were prepared with semi‐interpenetrating networks (s‐IPNs) by mixing a film‐forming polymer, poly(vinyl alcohol) (PVA), for the crosslinked matrix and a polyelectrolyte for the specific ion‐exchange property. Poly(sodium styrenesulfonate) (PSSNa), poly(styrenesulfonic acid) (PSSH), and poly(acrylic acid) (PAA) were used as anionic polyelectrolytes. Polyethyleneimine (PEI), poly(1,1‐dimethyl‐3,5‐dimethylenepiperidinium chloride) (PDDPCl), and poly(diallyldimethylammonium chloride) (PDDMACl) were used as cationic polyelectrolytes. Membranes with PVA 60% and polyelectrolyte 40% showed the best compromise among mechanical, homogeneous, and ion‐exchange properties. Gaseous dibromoethane was used as a crosslinking agent to form the PVA network and for efficient entrapment of the polyelectrolyte in the membrane. The crosslinking time (tc) was optimized for each type of membrane and its influence was studied by thermogravimetric analysis of the sample and scanning electron microscopy observations. The best results (large ion‐exchange capacity and small swelling ratio) were obtained for PVA/PAA and PVA/PSSNa/PSSH membranes. Among anion‐exchange membranes, PVA/PEI gave the best permselectivity (low co‐ion leakage) and the highest ion‐exchange capacity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1572–1580, 2002; DOI 10.1002/app.10420
Effect of hygrothermal aging history on sorption process, swelling, and glass transition temperature in a particle‐filled epoxy‐based adhesive
Authors: Fernández‐García M. , Chiang M. Y. M.
Published: October 2004

The effects of hygrothermal aging history and initial water content on sorption behavior and the physical properties of a commercial particle‐filled epoxy‐based adhesive were studied by the analysis of the water reabsorption process. ATR‐FTIR analysis was performed to characterize the hydrogen bond interactions among the water and either resin or fillers. Swelling behavior and the depression of the glass transition temperature (Tg) under different hygrothermal aging histories were related to the water in the apparent free volume of the adhesive. The results show that the water diffusion of the adhesive is a non‐Fickian process. It is also observed that swelling (which is reversible and consistent with hydrogen bond formation) and the rate of diffusion are not only dependent on the hygrothermal temperature but also the hygrothermal history. In addition, the swelling observed on the reabsorption process does not alter the apparent free volume of this adhesive system, and Tg depression is independent of the final equilibrium water content of the system. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1581–1591, 2002; DOI 10.1002/app.10447
Durable and regenerable antimicrobial textile materials prepared by a continuous grafting process
Authors: Sun Yuyu , Sun Gang
Published: October 2004

A cyclic‐amine monomer, 3‐allyl‐5,5‐dimethylhydantoin (ADMH), was grafted onto various textile materials in a continuous finishing process to prepare durable and regenerable antibacterial textiles. Highly efficient radical grafting polymerizations occurred inside or on the surfaces of fibers with the assistance of different initiators. In the finishing process, particular factors such as types and concentrations of radical initiators, drying, and curing conditions were rather important in effecting the final grafts of ADMH on fabrics and were studied carefully. After exposure to chlorine, the grafted hydantoin structures in the samples could be transformed into N‐halamines, which provided powerful, durable, and regenerable antibacterial activities. The influence of hydrophilic/hydrophobic properties of the fabrics on the antibacterial activities was discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1592–1599, 2002; DOI 10.1002/app.10456
Morphology and mechanical properties of unidirectional sisal– epoxy composites
Authors: Oksman Kristiina , Wallström Lennart , Berglund Lars. A. , Filho Romildo Dias Toledo
Published: October 2004

Plant fibers are of increasing interest for use in composite materials. They are renewable resources and waste management is easier than with glass fibers. In the present study, longitudinal stiffness and strength as well as morphology of unidirectional sisal–epoxy composites manufactured by resin transfer molding (RTM) were studied. Horseshoe‐shaped sisal fiber bundles (technical fibers) were nonuniformly distributed in the matrix. In contrast to many wood composites, lumen was not filled by polymer matrix. Technical sisal fibers showed higher effective modulus when included in the composite material than in the technical fiber test (40 GPa as compared with 24 GPa). In contrast, the effective technical fiber strength in the composites was estimated to be around 400 MPa in comparison with a measured technical fiber tensile strength of 550 MPa. Reasons for these phenomena are discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2358–2365, 2002
Kinetic study of hindered amine light stabilizer photografting in low density polyethylene films under natural weathering conditions
Authors: Kaci M. , Hebal G. , Benhamida A. , Boukerrou A. , Djidjelli H. , Sadoun T.
Published: October 2004

The photografting kinetic of a hindered amine light stabilizer (HALS) was studied in low density polyethylene (LDPE) films under natural weathering conditions. The HALS (PBH‐3) was added to the polymer at a concentration of 0.3% (w/w). The photografting kinetic of polymer bound HALS (PBH‐3) was determined by direct spectroscopic measurements through the absorption band area of the stabilizer centered at 308 nm in the UV spectra and 1605 cm−1 in Fourier transform IR (FTIR) spectra, which correspond to benzylidene malonate ester and benzylidene malonic groups, respectively. In parallel, measurements were carried out on the free PBH‐3 content after chloroform extraction of the photostabilizer from the polymer matrix by means of UV and gas chromatography methods. The results showed that in natural weathering the grafting of PBH‐3 occurred in the LDPE film after very short exposure times of 127 and 168 h as determined by UV and FTIR, respectively. Moreover, the curves describing both the photografting and the free HALS kinetics exhibited similar profiles. The mechanism of photografting implies a rapid photoreaction between the methylenic double bond of the stabilizer and the macroalkyl radicals of the polymer, resulting in formation of polymer‐bonded aminyl derivatives of the stabilizer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1524–1532, 2002; DOI 10.1002/app.10492
New soybean oil–styrene–divinylbenzene thermosetting copolymers. v. shape memory effect
Authors: Li Fengkui , Larock Richard C.
Published: October 2004

A series of new shape memory polymers are synthesized by the cationic copolymerization of regular soybean oil, low saturation soybean oil (LoSatSoy oil), and/or conjugated LoSatSoy oil with styrene and divinylbenzene, norbornadiene, or dicyclopentadiene initiated by boron trifluoride diethyl etherate or related modified initiators. The shape memory properties of the soybean oil polymers are characterized by the deformability (D) of the materials at temperatures higher than their glass‐transition temperatures (Tg), the degree to which the deformation is subsequently fixed at ambient temperature (FD), and the final shape recovery (R) upon being reheated. It is found that a Tg well above ambient temperature and a stable crosslinked network are two prerequisites for these soybean oil polymers to exhibit shape memory effects. Good shape memory materials with high D, FD, and R values are prepared by controlling the crosslink densities and the rigidity of the polymer backbones. The advantage of the soybean oil polymers lies in the high degree of chemical control over the shape memory characteristics. This makes these materials particularly promising in applications where shape memory properties are desirable. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1533–1543, 2002; DOI 10.1002/app.10493
Conversion of soybean oil into ion exchange resins: Removal of copper (II), nickel (II), and cobalt (II) ions from dilute aqueous solution using carboxylate‐containing resin
Authors: Liu Z. S. , Erhan S. Z.
Published: October 2004

An ion‐exchange resin containing carboxylic acid groups was prepared by reaction of epoxidized soybean oil with triethylene tetramine, followed by hydrolysis of glycerides by using sodium hydroxide solution. The cation exchange capacity of the resins was determined to be 3.50 mequiv/g. The adsorption capacity for Cu2+, Ni2+, and Co2+ on the obtained resin at pH 5.0 was found to be 192, 96, and 78 mg/g, respectively. Effect of pH on the adsorption capacity for copper (II), nickel (II), and cobalt (II) ions were also studied. Cu2+, Ni2+, and Co2+ were adsorbed at a pH above 3. These metal ions adsorbed on the resin are easily eluted by using 1N HCl solution. The selectivity of the resin for Cu2+ from mixtures containing Cu2+/Co2+/Ni2+ ions in the presence of sodium chloride was also investigated © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2386–2396, 2002
Studies on fly ash–filled epoxy‐cast slabs under compression
Authors: Kulkarni S. M. , Kishore
Published: October 2004

Filling a polymer with particulate material is generally attempted to improve the polymer properties and also realize some reduction in the cost. In the present work, we attempted to study the viability of using fly ash, an industrial waste with good mechanical properties, as a filler in epoxy. Initial low volumes of filler display an improvement in compressive strength and modulus. The experimental values of strength and modulus are also found to correlate well with those predicted by the rule of mixtures and modified Kerner's equation. At higher volume fractions, the decline in these properties is explained in the context of both percolation theory and Griffith's theory. The processes of failure initiation and propagation proposed are examined from the viewpoint of observations on the surfaces of compression‐failed samples in SEM. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2404–2410, 2002
Photo‐induced emulsion polymerization of vinyl acetate in the presence of poly(oxyethylene)10 nonyl phenyl ether ammonium sulfate, an anionic emulsifier (I)
Authors: Mah Soukil , Koo Donghun , Jeon Hyunjeong , Kwon Soonhong
Published: October 2004

Poly(vinyl alcohol) (PVA) having a number‐average degree of polymerization of 7000 was obtained from the poly(vinyl acetate) (PVAc) having a number‐average degree of polymerization 9000, a product of photo‐induced emulsion polymerization of vinyl acetate (VAc), carried out at 0°C, using poly(oxyethylene)10 nonyl phenyl ether ammonium sulfate as an anionic emulsifier. It was found that 100% conversion is always attained in the whole range of the investigation and the emulsifier plays an important role in the initiation process. The applicability of the photo‐induced emulsion polymerization system to a relatively large‐scale production was tested by using an apparatus equipped with an internal high‐pressure Hg lamp with a capacity of several hundred grams per batch under nitrogen atmosphere. It was found that both the rate of polymerization and the degree of polymerization of resulting polymers are slightly lower than those obtained from corresponding small‐scale polymerizations prepared on a high vacuum system because of the presence of oxygen. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2425–2431, 2002
Thermoreversible hydrogels. XV. Swelling behaviors and drug release for thermoreversible hydrogels containing silane monomers
Authors: Lee Wen‐Fu , Yuan Wen‐Yang
Published: October 2004

Three series of thermosensitive copolymeric hydrogels were prepared from [3‐(methacryloyloxy)propyl]trimethoxysilane (MPTMOS), [2‐(methacryloyloxy)ethoxy]trimethylsilane (METMS), and (methacryloyloxy)trimethylsilane (MTMS), referred to as the silane monomer, and N‐isopropylacrylamide (NIPAAm) by solution polymerization. The influence of the structures and amounts of silane monomers on the swelling and drug‐released behaviors were studied. The results showed that, because of the hydrophobicity of the silyl group, the more silane monomers in the copolymeric hydrogels the lower was the swelling ratio of the gels. The hydrophobicity of the silyl group affected the swelling mechanism, which resulted from the non‐Fickian diffusion for the gels. The copolymeric gels clearly exhibited gel transition temperatures. The copolymeric hydrogels could be applied to a drug‐release and drug‐delivery system. The delivery amount would approach a steady state after three cycle operations of delivery. The gels also showed an on–off switch behavior on drug release depending on the temperature, and the gels released more CV with the gels in a swollen state. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2523–2532, 2002
Effect of ultrasound on the physicochemical properties of organosolv lignins from wheat straw
Authors: Sun Runcang , Sun X. F. , Xu X. P.
Published: October 2004

The extractability and physicochemical properties of the wheat straw lignins were comparatively studied by using extraction methods with 0.5M NaOH in 60% aqueous methanol with and without application of ultrasonic irradiation. The results showed that applying sonication for 5, 10, 15, 20, 25, 30, and 35 min solubilized 67.4, 68.6, 74.4, 77.3, 77.3, 77.9, and 78.5% of the original lignin, whereas the treatment with 0.5M NaOH in 60% aqueous methanol at 60°C for 2.5 h without ultrasound assistance released 61.0% of the original lignin. The lignin preparations isolated by ultrasound‐assisted extractions showed slightly lower molecular weights, associated polysaccharides, and thermal stabilities during the initial stage of decomposition. More important, there were no significant differences in the primary structural features between the lignin preparations. Ultrasound‐assisted extractions under the alkaline organosolv extractions did not affect the overall structure of the lignin from wheat straw. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2512–2522, 2002
Bulk polymerization of styrene catalyzed by bi‐ and trifunctional cyclic initiators
Authors: Cerna J. R. , Morales G. , Eyler Gladys N. , Cañizo Adriana I.
Published: October 2004

A study of the bulk free‐radical polymerization of styrene in the presence of the cyclic bi‐ and trifunctional initiators cyclohexanone triperoxide, diethylketone triperoxide, acetone triperoxide, cyclohexanone diperoxide, and pinacolone diperoxide is reported. When these multifunctional initiators are used for styrene polymerization at high temperatures, it is possible to produce polymers with high molecular weights and narrow polydispersities at a high reaction rate. Additionally, the former initiators are used in a mixture that shows that the molecular parameters are influenced by the initiator concentration in the initiation system, in addition to the system employed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1–11, 2002
Synthesis of graft copolymers. III. Polystyrene‐g‐poly(butyl acrylate)
Authors: Morales Graciela , Guerrero Ramiro
Published: October 2004

Polystyrene (PS) chains functionalized with pendant 1,2‐bis(trimethylsilyloxy)tetraphenylethane (TPSE) groups are used as macroinitiators to initiate the polymerization of n‐butyl acrylate (BuA) to synthesize PS‐g‐poly(BuA) (PS‐g‐PBuA) copolymers at 130°C. The TPSE groups are known to function as initers in the polymerization of several vinyl monomers. The homolytic decomposition of TPSE results in a diphenylmethyl (DPM) radical attached to the main chain and a free DPM radical. The former is responsible for the polymerization initiation and the latter momentarily stops the growth of the growing grafts by the formation of a dormant species. Unfortunately, side reactions like the combination between growing grafts take place and the polymerization can only be controlled in a limited range of conversion. The most appropriate conditions for the synthesis of PS‐g‐PBuA are reported to present their potential use as thermoplastic elastomers with relatively controlled structures. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 19–26, 2002
The new face of gross anatomy
Authors: Reidenberg Joy S. , Laitman Jeffrey T.
Published: October 2004

The nature of anatomy education has changed substantially over the past decade due to both a new generation of students who learn differently from those of past years and the enormity of advances in anatomical imaging and viewing. At Mount Sinai School of Medicine, our anatomy courses have been designed to meld classic dissection with the tools physicians and surgeons will use tomorrow. We introduce students to the newest technologies available for viewing the body, such as minimally invasive approaches, ultrasonography, three‐dimensional visualizations, multi‐axial computerized image reconstructions, multi‐planar magnetic resonance imaging, and plastinated prosections. Students are given a hands‐on, team‐building experience operating laparoscopes in the laboratory. A great strength of our program is the important and active participation by faculty from 15 different basic and clinical departments, including several chairs and voluntary faculty. This interdisciplinary approach brings to our students direct, one‐on‐one encounters or presentations by our finest physicians and surgeons and our core anatomy faculty. In addition, the presence of many teaching assistants drawn from upper classmen and advanced graduate students adds an additional, vibrant dimension. Our anatomy programs for medical/graduate students and postgraduates are structured around three simple principles: (1) it is a privilege to teach, (2) we enlist only passionate teachers, and (3) it is our role to instill appreciation and respect for human form. Anat Rec (New Anat) 269:81–88, 2002. © 2002 Wiley‐Liss, Inc.
Hominid cranial bone structure: A histological study of Omo 1 specimens from Ethiopia using different microscopic techniques
Authors: Bartsiokas Antonis
Published: October 2004

The microstructure of a hominid cranial vault has not previously been studied to determine its tissue histology, and differences in comparison with that of modern humans. We selected the parietals of Omo‐Kibish 1, regarded as one of the oldest (about 130,000 years old) anatomically modern humans, and Omo 1 (Howell), which is a very recent human (about 2,000 years old)—both from the same area of Ethiopia. A combination of macrophotography, polarizing microscopy in the incident and transmission illumination mode, and confocal laser scanning microscopy (CLSM) was employed to examine thin sections, as well as polished and unpolished block faces of unembedded bone fragments, to minimize specimen destruction as much as possible. The methods enabled remarkably detailed information on bone microstructure and remodeling to be gleaned from tiny fragments of bone. The best method for examining fossilized human bones was shown to be that of incident light microscopy, which was the least destructive while producing the most amount of information. Unless the above methods are used, bone‐filling minerals, such as calcite, can cause erroneous estimations of bone thickness, as observations with the naked eye or even a magnifying glass cannot determine the limit between the cortex and the diploe. This is particularly important for sciences such as paleoanthropology, in which, for instance, a thick cranial bone of Homo erectus may be confused with a pathological one of H. sapiens and vice versa. Cross sections of parietal bones revealed differences between Omo‐Kibish 1 and Omo 1 (Howell) in diploic histology and in the relative thickness between the cortex and diploe, with the former specimen having an H. erectus ratio despite its H. sapiens gross anatomy. Omo‐Kibish 1 may still retain some affinities with H. erectus despite its being classified as H. sapiens. Newly described histological structures, such as the reverse type II osteons, the multicanalled osteons, and the osteocytomata are presented here. A modern human skeletal anatomy does not necessarily imply a modern human cranial bone histology. The outer circumferential lamellae of cranial bones are in essence growth lines. Cranial histology of hominids may provide useful information concerning their taxonomy and life history, including such factors as growth rate, developmental stress, and diet. Anat Rec 267:52–59, 2002. © 2002 Wiley‐Liss, Inc.
Abdominal situs inversus in a Holstein calf
Authors: Fisher K.R.S. , Wilson M.S. , Partlow G.D.
Published: October 2004

Situs inversus is a rare congenital anomaly wherein the normal, left–right organ location is inverted. The anatomical inversion (heterotaxy) is usually detected in routine radiography or other medical interventions. A 5‐month‐old Holstein heifer calf was identified as a suspected situs inversus totalis during abdominal surgery. Following surgery the calf did not gain weight. On admission to the Ontario Veterinary Hospital, it was given a routine clinical examination and a detailed cardiovascular, Doppler ultrasound examination, which appeared normal. Because of declining health and chronic bloating in the heifer, euthanasia was performed. A detailed post‐mortem dissection was carried out. No heart or lung anomalies were detected. Other thoracic organs were normal, except for a helical coil of the esophagus as it traversed the diaphragm. The rumen was located entirely on the right side of the abdomen and had a large area of adhesion to the parietal peritoneal wall. The left kidney was abnormally placed: retroperitoneal and cranial to the right. There were two spleens. The caudal vena cava was distended and twisted to the left. Thus the calf was situs inversus abdominalis. This suggests that the development of laterality in the early embryo may include both timing and positional regulation. Anat Rec 267:47–51, 2002. © 2002 Wiley‐Liss, Inc.
Comparative study of the innervation patterns of the hyobranchial musculature in three iguanian lizards: Sceloporus undulatus, Pseudotrapelus sinaitus, and Chamaeleo jacksonii
Authors: Meyers Jay J. , Herrel Anthony , Nishikawa Kiisa C.
Published: October 2004

The neuroanatomy and musculature of the hyobranchial system was studied in three species of iguanian lizards: Sceloporus undulatus, Pseudotrapelus sinaitus, and Chamaeleo jacksonii. The goal of this study was to describe and compare the innervation and arrangement of the hyobranchial musculature in the context of its function during tongue protrusion. A comparison of the hyobranchial innervation patterns revealed a relatively conserved innervation pattern in S. undulatus and P. sinaitus, and a modified version of this basic layout in C. jacksonii. All three species show anastomoses between sensory neurons of the trigeminal nerve and motor neurons of the hypoglossal nerve, suggesting that feedback may be important in coordinating tongue, jaw, and hyoid movements. The hyobranchial musculature of S. undulatus is very similar to that of P. sinaitus; however, there are minor differences, including the presence of an M. genioglossus internus (GGI) muscle in S. undulatus. Further differences are found mainly in functional aspects of the hyobranchial musculature, such as changes in the muscle lengths and the origins and insertions of the muscles. In C. jacksonii the hyobranchial system is comprised of largely the same components, but it has become highly modified compared to the other two species. Based on the innervation and morphological data gathered here, we propose a revision of the terminology for the hyobranchial musculature in iguanian lizards. Anat Rec 267:177–189, 2002. © 2002 Wiley‐Liss, Inc.
Spatial relation between major histocompatibility complex‐restricted antigen receptor‐bearing thymocytes and subtypes of thymic epithelial cells
Authors: Arudchelvan Yamini , Tokuda Nobuko , Sawada Tomoo , Shinozaki Fumihiko , Fukumoto Tetsuo
Published: October 2004

R73, a monoclonal antibody that recognizes a rat T cell surface antigen of TCRαβ, was used to identify thymocytes that express major histocompatibility complex‐restricted antigen receptors, and to define the spatial relation between these receptor‐bearing thymocytes and individual thymic cortical and medullary epithelial subtypes by ultrastructural immunohistochemistry. We show that in both the cortex and medulla 1) the thymocytes that reacted with R73 antibodies exhibited three staining patterns: cytoplasmic‐only staining, simultaneous cytoplasmic and surface membrane staining, and surface membrane‐only staining; 2) the subcapsular/perivascular epithelial cells (ECs) were usually associated with thymocytes expressing perinuclear staining only; and 3) the surface membrane areas of thymocytes that expressed antigen receptors made contact with pale and intermediate ECs, but not with dark cells. These results suggest that thymic selection of major histocompatibility complex restriction and/or tolerance may occur by interaction of the receptors on maturing thymocytes with major histocompatibility complex antigens on thymic ECs in general, and on pale and intermediate subtypes in particular. Anat Rec 267:131–136, 2002. © 2002 Wiley‐Liss, Inc.
Molecular genetics of sexual development in the mushroom Coprinus cinereus
Authors: Kamada Takashi
Published: October 2004

Sexual development in the mushroom Coprinus cinereus is under the control of two mating type loci, A and B. When two haploid homokaryons with compatible alleles at both A and B loci are mated, the coordinated activities of A‐ and B‐regulated pathways lead to formation of a mycelium termed the dikaryon, in which the two nuclei from the mating partners pair in each cell without fusing. The dikaryon is a prolonged mycelial stage that can be induced to develop a multicellular structure, the mushroom, under proper environmental conditions. The two nuclei fuse in specialized cells on the mushroom and immediately undergo meiosis to complete the sexual life cycle. It has been established recently that the A genes encode two classes of homeodomain proteins while the B genes encode pheromones and their receptors. More recently, molecular genetics has been used to reveal genes that work downstream of the mating type genes to regulate dikaryon formation, mushroom morphogenesis, and meiosis. BioEssays 24:449–459, 2002. © 2002 Wiley Periodicals, Inc.
Stabilizing the regionalisation of the developing vertebrate central nervous system
Authors: Pasini Andrea , Wilkinson David G.
Published: October 2004

During embryonic development, a number of tissues are patterned by their subdivision into domains with distinct regional identity. An important question is how sharp interfaces are established and maintained between adjacent domains despite the potential for scrambling due to cell intermingling during tissue growth. Two mechanisms have been found to underlie the maintenance of sharp interfaces: the specific restriction of cell mixing across boundaries, or the switching of identity of cells that cross between domains. We review the evidence for these mechanisms at distinct boundaries in the developing vertebrate central nervous system, and discuss what is known about their molecular mediators. BioEssays 24:427–438, 2002. © 2002 Wiley Periodicals, Inc.
Notching up another pathway
Authors: Brennan Keith , Gardner Philip
Published: October 2004

The Notch proteins play a vital role in cell fate decisions in both invertebrate and vertebrate development. Careful analysis of this role has led to a model of signalling downstream of these receptors, via the CSL (CBF1, Suppressor of Hairless, Lag‐1) family of transcription factors. There have been suggestions, however, that Notch can signal through other pathways. In the current paper, Ramain et al.1 provide compelling evidence for Notch signalling through a CSL‐independent pathway and they demonstrate that the cytoplasmic protein, Deltex, is required for this signal. In addition, they show that Wnt signalling may regulate this Deltex‐dependent signal. BioEssays 24:405–410, 2002. © 2002 Wiley Periodicals, Inc.
Unraveling the mechanisms of the vertebrate circadian clock: zebrafish may light the way
Authors: Pando Matthew P. , Sassone‐Corsi Paolo
Published: October 2004

Most organisms display oscillations of approximately 24 hours in their physiology. In higher organisms, these circadian oscillations in biochemical and physiological processes ultimately control complex behavioral rhythms that allow an organism to thrive in its natural habitat. Daily and seasonal light cycles are mainly responsible for keeping the circadian system properly aligned with the environment. The molecular mechanisms responsible for the control of the circadian clock have been explored in a number of systems. Interestingly, the circadian oscillations that are responsive to environmental stimuli are present very early during development. This review focuses on the advantages of using the zebrafish to study the development of the vertebrate circadian system and light‐dependent signaling to the clock. BioEssays 24:419–426, 2002. © 2002 Wiley Periodicals, Inc.
Binding modes of cyclic AMP and environments of tryptophan residues in 1:1 and 1:2 complexes of cyclic AMP receptor protein and cyclic AMP
Authors: Fujimoto Naoko , Toyama Akira , Takeuchi Hideo
Published: October 2004

Cyclic AMP (cAMP) receptor protein (CRP) forms 1:1 and 1:2 complexes with cAMP, and the former complex is considered to be the most active form of CRP in binding to specific DNA sequences and in modulating gene transcription by RNA polymerases. We examine the cAMP binding modes and structural changes of CRP upon cAMP binding by UV resonance Raman spectroscopy. The Raman spectra of CRP‐(cAMP)1 and CRP‐(cAMP)2 extracted from those of CRP–cAMP mixtures at varied mixing ratios clearly show that the hydrogen bonding state and the conformation of cAMP in both complexes in solution are very similar to those found in the X‐ray crystal structure of CRP‐(cAMP)2, which is evidence that the cAMP binding mode does not differ between the two complexes. The environmental hydrophobicity of Trp85 monitored by UV resonance Raman intensity shows a significant decrease upon binding of the first cAMP molecule, whereas no further change occurs in the second cAMP binding step. The environmental change of Trp85 suggests an opening of the cleft between the N‐terminal cAMP and C‐terminal DNA binding domains in the process of CRP activation by binding of a single cAMP molecule. © 2002 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 67: 186–196, 2002
Evidence for nonhydrogen bonded compound II in cyclic reaction of hemoglobin I from Lucina pectinata with hydrogen peroxide
Authors: De Jesús‐Bonilla Walleska , Ramírez‐Meléndez Eunice , Cerda José , López‐Garriga Juan
Published: October 2004

Studies that elucidate the behavior of the hemoglobins (Hbs) and myoglobins upon reaction with hydrogen peroxide are essential to the development of oxygen carrier substitutes. Stopped‐flow kinetics and resonance Raman data show that the reaction between hydrogen peroxide and oxygenated and deoxygenated ferric Hb I (oxy‐ and deoxy‐HbI) from Lucina pectinata produce compound I and compound II ferryl species. The rate constants ratio (k23/k41) between the formation of compound II from compound I (k23) and the oxidation of the ferrous HbI (k41, i.e., 25 M−1 s−1) of 12 × 10−4 M suggests that HbI has a peroxidative capacity for removing H2O2 from solution. Resonance Raman presents the formation of both, met‐aquo‐HbI and compound II ferryl species in the cyclic reaction of HbI with H2O2. The ferric HbI species is maintained by the presence of H2O2; it can produce HbI compound I, or it can be reduced to a deoxy‐HbI derivative to form HbI compound II upon reaction with H2O2. The compound II ferryl vibration frequency appears at 805 and 769 cm−1 for HbIFeIV16O and HbIFeIV18O species, respectively. This ferryl mode indicates the absence of hydrogen bonding between the carbonyl group of the distal Q64 and the HbIFeIVO ferryl moiety. The observation suggests that both the trans‐ligand effect and the polarizabilty of the HbI heme pocket are responsible for the observed ferryl oxo vibrational energy. The vibrational mode also suggests that the carbonyl group of the distal Q64 is oriented toward the iron of the heme group, increasing the distal pocket electron density. © 2002 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 67: 178–185, 2002
Excluded volume effects in gene stretching
Authors: Lam Pui‐Man
Published: October 2004

We investigate the effects excluded volume on the stretching of a single DNA in solution. We find that for small force F, the extension h is not linear in F but proportion to Fγ, with γ = (1 − ν)/ν, where ν is the well‐known universal correlation length exponent. A freely joint chain model with the segment length chosen to reproduce the small extension behavior gives excellent fit to the experimental data of λ‐phage DNA over the whole experimental range. We show that excluded volume effects are stronger in two dimensions and derive results in two dimensions that are different from the three‐dimensional results. This suggests experiments to be performed in these lower dimensions. © 2002 Wiley Periodicals, Inc. Biopolymers 64: 57–62, 2002
Surveying a local fitness landscape of a protein with epistatic sites for the study of directed evolution
Authors: Aita Takuyo , Hamamatsu Norio , Nomiya Yukiko , Uchiyama Hidefumi , Shibanaka Yasuhiko , Husimi Yuzuru
Published: October 2004

We present a method for analysis of a fitness landscape of a biopolymer with significantly epistatic sites. The analysis is based on a quasi‐additive fitness model. The fitness model is constructed with additive terms conducted by “site‐fitness” and epistatic terms conducted by “pair‐fitness,” where the site‐fitness is a fitness contribution from an independent residue and the pair‐fitness is a fitness contribution from a pair of epistatic residues. As a case study, we analyzed the sequence‐fitness data for 45 clones of thermostable prolyl endopeptidase mutants. They were generated by a mutation scrambling method, which can accumulate advantageous mutations. The fitness contributions from 14 single‐point mutations including E67Q and Q656R were identified by the analysis. As a result, we found that the fitness model with a significant epistatic term by a pair of the 67th site and 656th site was in good agreement with the experimental data and that the explored landscape in the binary 14‐dimensional sequence space is still a mountainous landscape with twin peaks. The validity was supported by the analysis of mutant fitness distributions derived from another mutation scrambling experiment and by (3D) structural data. © 2002 Wiley Periodicals, Inc. Biopolymers 64: 95–105, 2002
Monte Carlo study of cycloamylose: Chain conformation, radius of gyration, and diffusion coefficient
Authors: Nakata Yasushi , Norisuye Takashi , Kitamura Shinichi
Published: October 2004

Cyclic (1 → 4)‐α‐D‐glucan chains with or without excluded volume have been collected from a huge number (about 107) of linear amylosic chains generated by the Monte Carlo method with a conformational energy map for maltose, and their mean‐square radii of gyration 〈S2〉 and translational diffusion coefficients D (based on the Kirkwood formula) have been computed as functions of x (the number of glucose residues in a range from 7 to 300) and the excluded‐volume strength represented by the effective hard‐core radius. Both 〈S2〉/x and D in the unperturbed state weakly oscillate for x < 30 and the helical nature of amylose appears more pronouncedly in cyclic chains than in linear chains. As x increases, these properties approach the values expected for Gaussian rings. Though excluded‐volume effects on them are always larger in cycloamylose than in the corresponding linear amylose, the ratios of 〈S2〉 and the hydrodynamic radius of the former to the respective properties of the latter in good solvents can be slightly lower than or comparable to the (asymptotic) Gaussian‐chain values when x is not sufficiently large. An interpolation expression is constructed for the relation between the gyration‐radius expansion factors for linear and cyclic chains from the present Monte Carlo data and the early proposed asymptotic relation with the aid of the first‐order perturbation theories. © 2002 Wiley Periodicals, Inc. Biopolymers 64: 72–79, 2002
Strategies for manipulating the relative concentration of recombinant rotavirus structural proteins during simultaneous production by insect cells
Authors: Palomares Laura A. , López Susana , Ramírez Octavio T.
Published: October 2004

Adequate production strategies of virus‐like particles are among the challenges that must be addressed before such complex multimeric structures find practical applications as vaccines. Attainment of the correct stoichiometric relation between proteins that constitute virus‐like particles should result in an increased productivity by maximizing the concentration of assembled proteins and preventing the accumulation of waste monomers. In this work, strategies for manipulating the relative concentration between two of the structural proteins that constitute rotavirus‐like particles (VP2 and VP6) were explored using the insect cell baculovirus expression vector system. It was shown that multiplicity of infection is a useful tool for manipulating protein production rates and maximum concentrations in cultures expressing one or two recombinant proteins. Thus, multiplicity of infection can be employed for improving production of rotavirus‐like particles. VP2 and VP6 production rates obtained during individual infections remained unchanged when both were simultaneously produced, indicating that such rates can be utilized for estimating protein concentrations during coexpression. Manipulation of the time of infection between the two recombinant baculoviruses, proposed here for the first time, also proved to be effective for controling the relative protein concentrations. The use of such sequential infections constituted an effective production alternative that does not require high amounts of virus stocks and is easy to implement. In addition to VP2 and VP6, kinetic parameters for the individual production of the other two proteins (VP4 and VP7) that constitute rotavirus‐like particles were also obtained. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 635–644, 2002.
A kinetic model for surfactant inhibition of pentachlorophenol biodegradation
Authors: Cort Todd L. , Bielefeldt Angela R.
Published: October 2004

A kinetic model is used to describe the effect of the nonionic surfactant Tergitol NP‐10 (TNP10) on pentachlorophenol (PCP) biodegradation by Sphingomonas chlorophenolica sp. strain RA2. Different initial biomass to initial substrate ratios ranging from 13 to 418 were tested with 23 TNP10 concentrations ranging from 0 to 1500 mg/L. Tests were also conducted at 10°C and 20°C. No PCP biodegradation inhibition was observed at concentrations below the critical micelle concentration (CMC) of 50 mg/L. TNP10 concentrations above 100 to 200 mg/L were increasingly inhibitory to PCP biodegradation rates. This inhibition was best described by the Monod kinetic equation wherein the effect of TNP10 inhibition is reflected in the half‐saturation constant (Ks). The value of the Ks increased from between 1.5 and 13.5 mg/L with no surfactant present to 44 to 131 mg/L at 1000 mg/L TNP10. Using a standard competitive inhibition approach, the inhibition constant for TNP10 was approximately 100 mg/L at both 10°C and 20°C. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 606–616, 2002.
Measuring the pH environment of DNA delivered using nonviral vectors: Implications for lysosomal trafficking
Authors: Akinc Akin , Langer Robert
Published: October 2004

The degradation of DNA in lysosomes represents a major obstacle to efficient nonviral gene delivery. The rational design of vectors that overcome this obstacle requires a better understanding of the lysosomal barrier to gene delivery, which in turn requires a means to investigate this intermediate step. To this end, we developed a technique to measure the pH environment of delivered DNA, from which the degree to which vectors avoided trafficking to acidic Iysosomes could be determined. The measured average pH of DNA delivered using poly‐L‐lysine (PLL) polyplexes was 4.5, suggesting that PLL polyplexes were trafficked to acidic lysosomes. Other vectors could avoid or buffer the pH of Iysosomes as DNA delivered using Lipofectamine Plus, polyethylenimine (PEI), linear polyethylenimine (LPEI), and two degradable poly(β‐amino ester)s (poly‐1 and poly‐2) had average pH values of 7.1, 5.9, 5.0, 6.7, and 6.4, respectively. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 503–508, 2002.