bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seasonal variation in ovarian histology of the viviparous lizard Sceloporus torquatus torquatus
Authors: Uribe María Del Carmen A. , Omana María Elodia Mendez , Quintero JoséE. Gonzalez , Guillette Louis J. 
Published: February 2005

AbstractChanges in ovarian histology during the reproductive cycle of the viviparous lizard Sceloporus torquatus torquatus are described. In general, the variation in follicular histology observed during the seasonal cycle is similar to that of other lizards. Sceloporus t. torquatus exhibits a cycle in which small, previtellogenic follicles exist in the ovary from December to August. Vitellogenesis occurs between September and November, followed by ovulation from late November to early December. Parturition occurs the following spring. After ovulation, the remaining follicular cells form the corpus luteum and luteolysis did not occur until April‐May. Follicular atresia is commonly observed in previtellogenic follicles with polymorphic granulosa, but occurs less frequently in follicles during late vitellogenesis. There are two germinal beds in each ovary. The yolk nucleus is evident in young oocytes as is a vacuolated ooplasma prior to vitellogenesis. Extensive polymorphism is observed in yolk platelets. Mast cells and secretory cells are observed in the thecal layer of the follicular wall as are melanocytes in the ovarian stroma. © 1995 Wiley‐Liss, Inc.
Cytoplasmic bags: Containers for discarded paraflagellar membranes in spermiogenesis of graphosome lineatum (Pentatomidae, Hemiptera, Insecta)
Authors: Wolf Klaus Werner 
Published: February 2005

AbstractThe process of cytoplasmic sloughing is described in spermiogenesis of a stink bug, Graphosoma lineatum, using transmission electron microscopy of ultrathin sections. Tails of young spermatids possess a wide cytoplasmic layer lateral to the axoneme and the nenbenkern derivatives. Membranous sheets, comprised of cisternae of endoplasmic reticulum with very narrow lumina, are arranged parallel to these organelles. More advanced spermatids show only a thin cytoplasmic layer largely devoid of membranes. At this stage, large evaginations of the flagellar membrane, termed cytoplasmic bags, are found in association with the spermatid tails. The most prominent elements within these bags are concentric layers of endoplasmic reticulum of the type previously found in spermatid tails. This relationship suggests that the cells rid themselves of cytoplasmic membranes throughout spermiogenesis via inclusion into cytoplasmic bags. Upon release from the nucleate cytoplasm, the cytoplasmic bags become more and more electron‐dense and degenerate. © 1995 Wiley‐Liss, Inc.
Histological examination of flight muscle development and breakdown in Bemisia tabaci (Homoptera: Aleyrodidae): Relationship to age and flight behvior
Authors: Blackmer J. L. , Lindley V. A. , Byrne D. N. 
Published: February 2005

AbstractBemisia tabaci exhibited their longest flights between 3 and 5 days following adult eclosion. They rarely engaged in flight when they were < 4 hr old and were only capable of short‐duration flights after day 7. This difference in flight capacity appears to be associated with changes in the flight musculature and mitochondria. Myofibrils and mitochondria accounted for approximately 50% and 33% of the area within the flight muscles, respectively. These two elements, however, varied with the age and sex of the whitefly. The percentage of the total area occupied by myofibrils was lower in 9‐day‐old males relative to females and all other age categories. Sarcomere length decreased in older whiteflies, regardless of the sex. Myofibril diameter did not vary with the age of the whitefly, but the diameter of female whitefly myofibrils was greater than the diameter of male whitefly myofibrils. The number of myosin filaments within a myofibril unit increased with age, peaking at 5 days of age for females and 7 days of age for males. In all age groups, females had more myosin filaments than were found in males.Changes in mitochondria and levels of glycogen were related to the observed differences in flight activity. The area occupied by mitochondria was small in < 4‐h‐old and 9‐day‐old whiteflies, and mitochondrial cristae were undeveloped in newly emerged whiteflies. In 7‐ and 9‐day‐old whiteflies the cristae began to separate, leaving visible spaces within the mitochondria. Glycogen granules were abundant in the flight musculature of newly emerged (< 4‐hr‐old), 1‐day‐old and 3‐day‐old whiteflies, but by 5 days of age only 25% of whiteflies contained glycogen granules. Seven‐ and 9‐day‐old whiteflies contained no visible glycogen.An examination of the flight muscle of whiteflies after flights of varying duration (up to 60 min) revealed no relationships between flight duration and the number of mitochondria or the percentage of the total area occupied by mitochondria. There was, however, a positive relationship between flight duration and the percentage of total area occupied by myofibrils. © 1995 Wiley‐Liss, Inc.
Buccal glands of adults of the lamprey Mordacia mordax, including comparisons with other species
Authors: Potter I. C. , Thomson G. J. , Cook R. D. , Cox J. M. , Macey D. J. 
Published: February 2005

AbstractMordacia mordax is one of the two anadromous parasitic lamprey species of the southern hemisphere family Mordaciidae. Its adults possess two lateral buccal glands and one central buccal gland. When the tongue‐like piston is retracted, the buccal glands occupy much of the opening of the oral cavity at the rear of the buccal cavity. The glands contain numerous tube‐like, ductless secretory units, which discharge directly into the buccal cavity. Their secretory epithelial cells contain numerous granules, some of which are zymogen‐like, while others have a beaded, spiralled appearance. The similarity of the latter to mast cell granules suggests that they may likewise produce an anticoagulant, which would be valuable to a presumed blood feeder such as M. mordax. The mucus produced by these cells could act as a carrier for the secretions and as an adhesive for promoting retention of t he secretions on the host's surface. When the young adults is transferred to salt water, the buccal glands increase their production and discharge of secretions. Since the glands are not enclosed in musculature, their secretions are probably discharged by mechanical pressure applied by the forward movement of the head of the tooth‐bearing piston into the buccal cavity. An account is given of the way in which the location, number, glandular organization, secretory granules, and type of secretion of the buccal glands of M. mordax, and thus presumably also their mode of function, differ markedly from those of members of the other lamprey family found in the southern hemisphere, and of all holarrctic lampreys. © 1995 Wiley‐Liss, Inc.
Measurement of mechanical properties of ligament substance from a bone‐ligament‐bone preparation
Authors: Woo S. L‐Y. , Gomez M. A. , Seguchi Y. , Endo C. M. , Akeson W. H. 
Published: February 2005

AbstractThis investigation presents a new approach in the measurement of the mechanical properties of the ligament substance from tensile testing of a bone‐ligament‐bone complex. Such basic information should be one of the necessary prerequisites in the evaluation of ligament repair as well as reconstruction by autogenous tissue grafts or artificial ligament implants. The use of a video system permits the determination of tensile strains of the mid‐medial collateral ligaments from the canine, swine, and rabbit without mechanically interfering with the ligament deformation during testing. This methodology further eliminates the difficulties of measuring the initial length of the entire medial collateral ligament, as its insertions to bones are ambiguous and cover a large area. It was found that the strain of the ligament substance is consistently and considerably less than specific deformation of the bone‐ligament‐bone complex. These data suggest that the ligament‐bone structure stretches nonuniformly with the highest deformation occurring near or at the ligament insertion sites to bone. Other interesting findings include the variation of tensile strains along the ligament substance for all animal species studied.
The origin of stress‐generated potentials in fluid‐saturated bone
Authors: Pienkowski D. , Pollack S. R. 
Published: February 2005

AbstractThe objective of this study was to determine the origin of stressgenerated potentials (SGPs) in fluid‐saturated bone. Stress‐generated potentials were studied as a function of the conductivity, NaCl concentration, and viscosity of the fluid contained within cortical human and bovine bone. Bone samples were soaked in solutions in which NaCl and sucrose concentrations were systematically varied. Macroscopic SGPs and their relaxation times were measured as a function of these properties. Stress‐generated potentials were also measured as a function of conductivity and NaCl concentration by using a microelectrode. The results of this study confirmed that the properties of the fluid in bone have a great influence on the magnitude and time dependence of the SGP. Especially notable was the observation that solutions of high NaCl concentration consistently reversed the polarity of the SGP. These results are consistent with streaming potential theory. Although fluid‐saturated bone may retain some piezoelectric properties, SGPs are predominantly caused by streaming potentials.
Comparison of mechanical work and metabolic energy consumption during normal gait
Authors: Burdett Ray G. , Skrinar Gary S. , Simon Sheldon R. 
Published: February 2005

AbstractThe validity of using mechanical measures of work to indicate the metabolic energy consumption during normal gait was examined. These mechanical measures were (a) mechanical work done on the center of mass per kilogram body mass per second (\documentclass{article}\pagestyle{empty}\begin{document}$ \dot W_{{\rm cm}} $\end{document}), calculated by integration of ground reaction forces measured by force platforms; (b) total body segmental work per kilogram body mass per second (\documentclass{article}\pagestyle{empty}\begin{document}$ \dot W_{{\rm seg}} $\end{document}), calculated from individual body segment energies measured by motion analysis; and (c) the sum of the normalized absolute moment impulses per second acting on the joints of the lower extremities (\documentclass{article}\pagestyle{empty}\begin{document}$ \dot M $\end{document}), calculated from both force and motion data. The metabolic energy consumption, determined by analysis of expired air, and the three mechanical measures of work were calculated for six normal subjects walking at five speeds. Each measure of mechanical work per second walked was highly correlated with metabolic energy consumption/kg · s (r = 0.89 for Wcm, r = 0.79 for \documentclass{article}\pagestyle{empty}\begin{document}$ \dot W_{{\rm seg}} $\end{document}, and r = 0.85 for M), but a poorer correlation was found between each measure of mechanical work per meter walked and net metabolic energy consumption/kg. m (r = 0.54 for Wcm, r = 0.28 for Wseg, and r = 0.03 for M). These mechanical parameters, particularly when measured per time, may be useful in comparing metabolic energy consumption between individuals or between different walking conditions for the same individual.
Comparative cost of walking in young and old adults
Authors: Waters Robert L. , Hislop Helen J. , Perry Jacquelin , Thomas Lynn , Campbell Joyce 
Published: February 2005

AbstractNormative data that summarize the energy requirements and gait characteristics of level outdoor walking were determined in 111 normal subjects between the ages of 20 and 80 years. Subjects were divided into two age groups: young adults (20–59 years) and senior subjects (60–80 years). The mean rate of oxygen consumption for young adults and senior subjects did not significantly differ, averaging 11.9 ml/kg‐min for both groups. The data on heart rate paralleled the findings on oxygen consumption, averaging 100 and 103 beats/ min, respectively. The net oxygen cost per meter walked for senior subjects, 0.16 ml/kg‐m, was significantly greater (p < 0.0005) than the value for young adults, 0.15 ml/kg‐m, due to a decline in the average walking speed. The average gait velocity for senior subjects, 73 m/min, was statistically significantly less (p < 0.0005) than the values for the younger adults, 80 m/min.
Tissue response to carbon‐reinforced polyethylene
Authors: Groth Harry E. , Shilling Joel M. 
Published: February 2005

AbstractThere has been clinical concern about the gray discoloration in synovial tissue adjacent to carbon‐reinforced polyethylene total joint implants. To evaluate the pathologic response of the synovium to this material, synovial specimens from 11 total ankle cases with carbon‐reinforced tibial components and two synovial specimens from cases with standard polyethylene tibial components were studied by gross and histologic techniques. Polyethylene debris was found to produce a significant synovial reaction with histiocytes and foreign body giant cells. This was found in both the carbon‐reinforced cases and in those cases without carbon‐reinforced components. This reaction is also seen in revisions of total hips and total knees in which standard polyethylene components have been implanted. In contrast with this, carbon particles produced only a minimal reaction in the synovial tissue. Carbon appears to be an extremely benign implant material, and synovial discoloration from shed carbon fibrils does not appear to present a significant clinical problem.
An experimental polyarthritis associated with systemic antigen excess in immune rabbits
Authors: Kawai Kazuo , Scudamore R. Allan , Cooke T. Derek V. 
Published: February 2005

AbstractRabbits were immunized with bovine serum albumin and later challenged intraperitoneally with the same antigen. Polyarthritis, characterized by synovial lining layer hyperplasia and leukocyte infiltration, was conditional on animals having excess free serum antigen in the presence of circulating immune complexes (IC). Nonimmune controls did not develop polyarthritis following antigen challenge. Data are presented that strongly suggest that synovitis was triggered by deposition of IC in the synovia. During the chronic phase of polyarthritis the synovium was clear of antigen but there was marked retention within joint fibrocartilage, suggesting that antigen, immobilized locally, may maintain the chronic synovitis. Clinical relevance: There are several animal models in which experimental arthritis has been induced by antigenic challenge. The resemblance of the lesions to those of human rheumatoid arthritis has provided the rationale for studying the immune events associated with the onset of acute and maintenance of chronic phases of experimental arthritis.
Effects of increased systemic blood pressure on the tissue fluid pressure threshold of peripheral nerve
Authors: Szabo Robert M. , Gelberman Richard H. , Williamson Richard V. , Hargens Alan R. 
Published: February 2005

AbstractThis study was designed to evaluate the functional response of the median nerve at the wrist to various degrees of acute, local compression in hypertensive patients. After measuring resting tissue fluid pressure in the carpal tunnel of the nondominant hand of nine subjects (diastolic pressures of 90 mm Hg or greater), localized pressures of 50, 60, or 70 mm Hg were applied to the palmar aspect of the wrist. Motor and sensory latencies and amplitudes of the median nerve were evaluated before compression, during 30–240 min of compression, and during the postcompression recovery phase. Sensory responses were completely blocked at a threshold tissue fluid pressure of 60–70 mm Hg, measured by the wick catheter technique. This pressure threshold was greater than the 40–50 mm Hg previously found in normotensive subjects. The tissue pressure threshold of normotensive and hypertensive subjects was consistently 30 mm Hg below diastolic blood pressure (approximately 45 mm Hg below mean arterial blood pressure). These results support the concept that ischemia is the prime mechanism of conduction block in low pressure, nerve‐compression syndromes.
Blood flow and bone uptake of99mTc‐labeled methylene diphosphonate
Authors: Riggs Stanley A. , Wood Michael B. , Cooney William P. , Kelly Patrick J. 
Published: February 2005

AbstractIn mature dogs with comparable levels of bone remodeling, we produced either increased (with adenosine triphosphate) or decreased (with epinephrine) blood flow to one hindlimb. In 13 dogs (five control, four with increased flow, and four with decreased flow), we compared uptake, at 3 h after injection of radiolabeled diphosphonate in the mid‐tibia, with blood flow as determined by microspheres. Blood flow was determined with 85Sr‐labeled microspheres, and determination of uptake of 99mTc methylene diphosphonate (99mTc‐MDP) was by a gamma detector. There was a linear relationship between changes in diphosphonate uptake and changes in blood flow at decreased and normal flows; however, at high flows the relationship was nonproportional, indicating a disproportionately slower increase in 99mTc‐MDP uptake with increasing blood flow. In six dogs an initial 1‐h uptake curve of 99mTc‐MDP was determined in both control and experimental limbs under states of increased and decreased blood flow. The 30‐min uptake value, 60‐min uptake value, area under the curve, and the slope of the curve were related to flow as determined by microspheres. The data are consistent with the hypothesis that deposition of bone‐concentrating isotopes such as 99mTc‐MDP is partly controlled by blood flow; at subnormal and normal flows tracer uptake is closely related to blood flow, but at supranormal flow rates it is not and appears to be diffusion limited.
Fracture of long bones: Rate effects under singular and combined loading states
Authors: Peterson D. L. , Skraba J. S. , Moran J. M. , Greenwald A. S. 
Published: February 2005

AbstractThis study was undertaken to determine the effect of loading rate on bone failure under singular and combined loading states. Using the entire loading range of an Instron Materials Testing Machine, 190 pairs of canine radii were tested. One bone of each pair was subjected to either torsional or a combination of axial and torsional loads, and compared with a control specimen. Compressive loads of 4.6 and 11.5 N were utilized. Torque to failure and energy data versus loading rate were plotted. As loading rate increased, the torque and energy values were found to increase, reach a peak, and then decline at higher rates. Fractures produced under the combined state of loading are representative of those clinically found in human trauma situations.
A study of factors influencing muscle activity about the knee joint
Authors: Andriacchi T. P. , Andersson G. B. J. , Örtengren R. , Mikosz R. P. 
Published: February 2005

AbstractSeveral factors influencing the myoelectric activity of muscles surrounding the knee joint were studied using fine‐wire monopolar electrodes. The muscles studied included the vastus lateralis, vastus intermedius, rectus femoris, vastus medialis, gracilis, sartorius, biceps femoris, semimembranosus, semitendinosus, tensor fasciae latae, medial head of the gastrocnemius, and lateral head of the gastrocnemius. Muscle activity was measured in response to unidirectional loads tending to flex and extend the knee, and to combined loads of flexion‐adduction, flexion‐abduction, extension‐adduction, and extension‐abduction. Results indicate that the individual muscle responses are dependent upon the direction, magnitude, and combination of external moments, as well as on the flexion angle of the knee joint. Muscle response appeared to be influenced by certain intrinsic mechanical characteristics of the knee joint that tend to change the moment arms of the muscles as the knee moves. For example, the substantial changes in quadriceps myoelectric activity with knee flexion, with constant load applied, can be related to the movement of the tibial‐femoral contact changing the lever arm of the quadriceps mechanism. This study indicates that the mechanics of the knee joint must be taken into consideration while attempting to interpret or predict the load response of muscles crossing the knee joint.
Joint position sense in total knee arthroplasty
Authors: Skinner Harry B. , Barrack Robert L. , Cook Stephen D. , Haddad Ray J. 
Published: February 2005

AbstractSeventeen postoperative total knee arthroplasty (TKA) patients were evaluated using two tests of knee joint position sense. Young controls and age‐matched controls underwent identical tests. The TKA patients also underwent gait analysis, including foot switch stride analysis, and clinical evaluation using a standard scoring system. Results showed statistically significant decreases in joint position sense from young controls to old controls, and further significant decreases with joint disease; however, no further worsening was noted as a result of TKA. The abnormal gait parameters seen in TKA patients correlated as well with position sense as with clinical score. Strongest correlations were seen when a combined clinical and proprioceptive score was compared with gait parameters. In spite of alleviation of pain and correction of deformity, normal gait and function are not typically achieved after total knee replacement. Irreversible loss of joint proprioceptive function due to the disease process may be a major factor in the discrepancy between clinical and functional outcomes of total joint arthroplasty. Furthermore, loss of proprioception and the resulting abnormal gait patterns may place increased stress on components and contribute to loosening. In addition, an association between degenerative joint disease and decline in proprioception is suggested.
Allogenic transplants of bone revascularized by microvascular anastomoses: A preliminary study
Authors: Moore J. Russell , Phillips Thomas W. , Weiland Andrew J. , Randolph Mark A. 
Published: February 2005

AbstractAn area of experimental bone grafting that needs further study is the use of free vascularized allografts of bone. In 35 outbred mongrel dogs, the viability of vascularized bone allografts with and without azathioprine immunosuppression was compared to vascularized autogenous bone grafts. Viability was assessed by histologic techniques, fluorochrome bone labeling, and electron microscopy. Autogenous vascularized bone grafts remained viable, and it was concluded that microvascular technique was not the limiting factor in attaining survival of the grafts. The behavior of autogenous vascularized bone grafts with and without the influence of azathioprine was similar. Allogenic vascularized bone transplants uniformly failed at a period between 2 and 3 weeks. Immunosuppression with azathioprine did not appreciably affect survival of the osteocytes. However, the host response to the foreign tissue was slightly modified. The clinical ramifications of bone transplantations in humans are not analogous to the clinical situation of transplantation of other organs. If vascularized bone transplants are performed in humans, a relatively safe form of immunosuppression is necessary. This study suggests that azathioprine alone does not offer sufficient immunosuppression to insure viability of the vascularized transplant.