bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of adriamycin on hamster molar tooth development in vitro: 1. Morphological changes
Authors: Karim A. C. , Woltgens J. H. M. , Bervoets Th. J. M. , Lyaruu D. M. , Bronckers A. L. J. J. 
Published: February 2005

AbstractThe effect of adriamycin (1 mg/liter) on the development of the golden hamster 3‐day‐old second maxillary molars (M2) was investigated in vitro. Exposure of the molars to 1 mg/liter adriamycin during the first 2 hours of culture produced smaller teeth 3–7 days later, as determined by measurements of dry weights and by histological observations. Higher doses caused severe necrosis. The more differentiated pulp fibroblasts showed osteodentin formation 3 days after treatment with adriamycin (1 mg/liter), while the more immature ones underwent necrosis. The phenotypic changes brought on by the drug were permanent, and osteodentin continued to be formed throughout the course of this study. In addition the cervical loop region was inhibited from growing, while the production of the matrices of enamel and dentin appeared to be increased at 3 and 5 days after treatment. Electron microscopy of the forming osteodentin matrix revealed a random arrangement of banded collagen fibers during the early stage of osteodentin formation. As more matrix was formed, the collagen became quite compact and appeared quite similar to dentin. Finally, matrix vesicles were found among the collagenous matrix that was not yet mineralized. With the exception of the increased production of enamel and dentin, these in vitro results confirmed those earlier in vivo studies on the effect of adriamycin on rat incisor tooth.
Ultrastructural and cytochemical study of elastic fibers in the ventral aorta of a teleost, Anguilla japonica
Authors: Isokawa Keitaro , Takagi Minoru , Toda Yoshihisa 
Published: February 2005

AbstractPrevious studies have revealed that amorphous elastin and microfibrils are structural entities of mammalian elastic fibers. Elastin shows a wide phylogenetic distribution, but the presence of elastin‐associated microfibrils has not been demonstrated in teleost aorta. Thus, we have ultrastructurally and cytochemically examined elastic fibers in the ventral aorta of eel, a teleost, by utilizing routine uranyl acetate and lead double staining, the tannic acid (pH 7.0)—uranyl acetate (TA‐UA) method, elastase en bloc digestion, Thiéry's periodic acid‐thiocarbohydrazide‐silver proteinate (PA‐TCH‐SP) method, and the horseradish‐peroxidase‐labeled concanavalin A (Con A) method. In the ventral aorta of eel, a little ultrastructural difference between elastic fibers in the intima and media and those in the adventitia was noticed, but in either tunic each elastic fiber was basically composed of a “fibrillar core” and surrounding microfibrils. The fibrillar core was a collection of fibrils which showed a tendency to coalesce with each other, and these constituent fibrils were TA‐UA positive and elastase‐sensitive, representing their nature of elastin. By contrast, microfibrils associated with the fibrillar core were TA‐UA negative and elastase‐resistant, and their glycoproteinaceous nature was demonstrated by PA‐TCH‐SP and Con A methods. Thus, this study provides evidence for the presence of elastin‐associated microfibrils in teleost aorta. These results are discussed in relation to the topographical difference of elastic fibers in eel aortic wall.
Intra‐articular synovial folds of thoracolumbar junction zygapophyseal joints
Authors: Singer Kevin P. , Giles Lynton G. F. , Day Robert E. 
Published: February 2005

AbstractTransverse histological sections from T10‐11, T11‐12, T12‐L1, and L1‐2 zygapophyseal joints were examined in 32 post‐mortem spines, using light microscopy, to record the presence of intra‐articular synovial fold inclusions. In addition, three mid‐joint sections from each joint were photographed using 35 mm colour film. From these slides, linear dimensions of the extent of intraarticular synovial fold projection between the zygapophyseal joints were measured using computer‐aided planimetry. Small, fibrous folds were commonly found at the joint margins extending from the ligamentum flavum and the fibrous joint capsule. Larger, fibro‐adipose synovial folds, projecting between the articular surfaces, were also noted, particularly at T12‐L1 and L1‐2.
Regression of ventricular hypertrophy abolishes cardiocyte vulnerability to acute hypoxia
Authors: Canby Craig A. , Tomanek Robert J. 
Published: February 2005

AbstractLeft ventricular hypertrophy (LVH) secondary to a pressure overload commonly leads to perfusion abnormalities that may limit oxygen delivery to the myocardium and, therefore, result in cardiocyte intracellular damage. We initiated this study to test the hypothesis that the increased vulnerability of the hypertrophied left ventricle to acute hypoxia is minimized when LVH regresses and maximal coronary flow returns to normal. Six‐month‐old spontaneously hypertensive (SHR) and normotensive Wistar‐Kyoto (WKY) rats were divided into control or one of two antihypertensive treatment groups. A 3‐month treatment consisted of captopril (75‐100 mg/kg) or hydralazine (80‐160 mg/L) with hydrochlorothiazide (500 mg/L) added to each therapy. At the conclusion of the treatment period, the rats were administered a 7% O2‐93% N2 gas mixture for 20 minutes to induce acute hypoxic stress during which time hemodynamics, blood gases, and pH were monitored. The heart was then rapidly fixed by vascular perfusion and prepared for electron microscopy. Captopril and hydralazine were equally effective in lowering arterial pressure in both strains, but only captopril was efficacious in reducing heart mass. Hypoxia‐induced changes in hemodynamics, blood gases, and pH were similar in all of the groups; PO2 was decreased by about 70%. The electron micrographs revealed that the hypertrophied left ventricle consistently showed morphologic evidence of hypoxic damage (as indicated by T‐tubular swelling, intracellular edema, and mitochondrial alterations); in contrast hypoxia had little effect on the non‐hypertrophied ventricle. Captopril treatment resulted in a disappearance of the lability to hypoxic damage while hydralazine caused a small reduction in the frequency of hypoxic damage. In conclusion, reversal of hypertension alone had little effect on cardiocyte vulnerability to acute hypoxia, but reversal of hypertension in conjunction with regression of LVH prevented the intracellular damage characteristic of hypoxia. Thus, LVH and its associated maximal perfusion decrement, rather than hypertension per se, underlie cardiocyte vulnerability to hypoxic stress.
Intercellular communication within the rat anterior pituitary Gland. I. Postnatal development and changes after injection of luteinizing hormone‐releasing hormone (LH‐RH) or testosterone
Authors: Soji Tsuyoshi , Yashiro Takashi , Herbert Damon C. 
Published: February 2005

AbstractThe postnatal development of gap junction formation and cell‐to‐cell communication were investigated in male rats from 10 through 40 days of age. These junctions initially appeared between adjacent folliculo‐stellate cells on day 20. Their numbers increased until the animals reached the age of 40 days, when their frequency reached a level that resembled that found in adults. The ontogeny of these junctions was examined in rats treated with luteinizing hormone releasing hormone (LH‐RH) or testosterone. The two hormones were injected for 1 week into rats aged 3, 13, 23, or 33 days. The appearance of gap junctions was accelerated in a similar fashion by LH‐RH and testosterone, with their formation and numbers being advanced by 10 days over that observed in the untreated controls. The results suggest a role for the gonadal steroid hormones in the formation of gap junctions in the rat hypophysis.
Modulation of basal and FSH‐dependent cyclic AMP production in rat seminiferous tubules staged by an improved transillumination technique
Authors: Kangasniemi Marko , Kaipia Antti , Mali Pekka , Toppari Jorma , Huhtaniemi Ilpo , Parvinen Martti 
Published: February 2005

AbstractThe stage‐dependent action of follicle‐stimulating hormone (FSH) in the rat seminiferous epithelium was investigated in microdissected 1 mm tubule segments, where the precise stage of the cycle was identified by a rapid screening method of live cell squash preparations. For distinction of stages I and II and the substages of VII, new criteria were used. The step 16 spermatids with rapid assembly of outer dense fibers leading to marked increase of flagellar thickness were used for distinction of stages I and II. The form and density of the cytoplasmic lobes of step 19 spermatids was used for recognition of substages of VII.Highest basal production of cyclic AMP (cAMP, measured by radioimmunoassay) was found in stage II of the cycle and stages XIV‐I‐VI had higher values than did stages VII‐XIII. A decline occurred during stage VII and an increase at stage XIV. When stimulated with FSH, highest cAMP secretion was found in stage IV of the cycle; again, stages XIV‐I‐VI had higher values than did other stages. A small but significant (P < .01) stimulation was found at substage VIId. FSH‐stimulated and basal cAMP productions of different stages were compared, highest values were found at stages IV and XIII, and lowest, at stages VIIa‐c and IX of the cycle.Since the FSH‐dependent cAMP production is confined to Sertoli cells, and the number of these cells is constent per unit length of seminiferous tubules, the Sertoli cells are obviously under a stage‐specific paracrine control by the surrounding spermatogenic cells. Specific steps in cell differentiation, such as spermatogonial proliferation, final maturation of the spermatids (stages I‐VII), onset of meiosis (substage VIId), and completion of meiotic divisons (stage XIV) may be involved in this interaction.
Cytoskeletal organization and synthesis in substrate‐independent and ‐dependent myogenesis in chick embryos
Authors: Daniels Karla J. , Sandra Alexander 
Published: February 2005

AbstractChick embryo myoblasts were fused in suspension culture to form myoballs by modification of previous procedures that excluded the use of divalent ion chelators and antimitotic drugs and included the continuous presence of serum in order to analyze the organized appearance and synthesis of major cytoskeletal proteins during cell attachment and spreading. The organization of the major cytoskeletal proteins actin, tubulin, and vimentin was assessed by fluorescence microscopy under these conditions as well as under conditions in which the myoballs were allowed to attach and spread on a collagen‐coated substrate. Actin, detected by fluorescence microscopy, stained myoballs diffusely and was reorganized to form stress fibers in the attached and spreading myoball. Nuclei were segregated to a centrally located lattice of microtubules. The microtubule‐specific drugs nocodazole and taxol prevented myoball spreading and the establishment of myotube polarity, respectively. Vimentin appeared as wavy ribbons in a perinuclear position around attached and spreading myoballs. In parallel studies, the synthesis of these cytoskeletal proteins was analyzed by radioisotopic labeling and polyacrylamide gel electrophoresis. These studies showed that myoballs possess altered ratios of actin and tubulin isoforms and of phosphorylated and nonphosphorylated vimentin compared to myotubes. These ratios rapidly change to the myotube pattern when myoballs are allowed to attach to solid substrata. Thus, although both myoballs and myotubes undergo muscle‐specific differentiation, their cytoskeletal proteins are morphologically and biochemically distinct.
Morphological analysis of contracting and quiescent adult rabbit cardiac myocytes in long‐term culture
Authors: Decker Marlene L. , Simpson David G. , Behnke Monica , Cook Melissa G. , Decker Robert S. 
Published: February 2005

AbstractIsolated rabbit ventricular cardiac myocytes adapt readily to primary culture. As the myocytes spread and flatten over the culture substratum, the myofibrillar apparatus retains a “rod‐like” orientation. Development of contractile activity is crucial in the maintenace of the integrity of the myofibrillar apparatus during prolonged culture. Myocytes that fail to beat display morphological indications of atrophy; conversely, myocytes that commence beating show no such morphological signs of myofibrillar disorganization. The subcellular organization of other elements of the contractile apparatus, including the transverse tubular system and the sarcoplasmic reticulum, retain their structural relationship with the myofibrils in beating myocytes but not in quiescent cells. Cultured adult myocytes represent an important model to investigate the influence of mechanical factors on the organization and maintenance of the adult cardiac phenotype.
Immunohistochemical localization of type X collagen in the proximal tibiotarsi of brolier chickens and turkeys
Authors: Haynes Joseph S. 
Published: February 2005

AbstractType X collagen is a prominent component of the extracellular matrix in cartilage destined to mineralize during endochondral ossification, yet its role is only now being determined. As a prelude to determining what, if any, alterations occur in the distribution of type X collagen in growth plates of poultry with rickets or tibial dyschondroplasia, our objective in the current study was to determine the distribution of type X collagen in the proximal tibiotarsi of broiler chickens and turkeys from 1 day of age through physeal closure. Proximal tibiotarsi from five male broiler chickens, five female broiler chickens and five male turkeys were collected at 1, 7, 14, 28, 56, and 98 days of age and processed for immunohistochemistry; a monoclonal antibody for type X collagen was used to demonstrate type X collagen distribution.Our findings indicate that type X collagen is produced in the prehypertrophic and early hypertrophic zones of the avian growth plate and is incorporated into the extracellular matrix in these zones. Furthermore, intracellular type X collagen is markedly decreased in more mature areas of the growth plate, although type X collagen is markedly decreased in more mature areas of the growth plate, although type X collagen remains a prominent component of the extracellular matrix unitl the matrix is completely resorbed. In addition, the distribution of type X collagen is similar in the proximal tibiotarsi of broiler chickens and turkeys at comparable stages of endochondral ossification and distribution of type X collagen in the secondary center of ossification parallels that in the physis.
Induction of stein‐leventhal‐like polycystic ovaries (PCO) in the rat: A new model for cystic ovarian disease
Authors: McCarthy Gerald F. , Brawer James R. 
Published: February 2005

AbstractAn injection of estradiol valerate (EV) in the rat produces an anovulatory polycystic ovarian (PCO) condition. Chronic estrogen exposure, produced by subcutaneously implanted, estradiol (E2)‐containing chronic release capsules, results in acyclicity and in hypothalamic changes similar to those seen in the EV‐injected rat. We, therefore, examined the ovarian histology and plasma gonadotropin patterns in the E2‐implanted rat and found that this model exhibits a poiycystic ovarian condition and a plasma gonadotropin pattern very different from those in the EV‐treated model. The plasma patterns of LH and FSH are bimodal consisting of small frequent pulses as well as less frequent large episodes of long duration. The ovaries contain multiple small cysts, characterized by an extensively hypertrophied theca interna, and vast chords of hypertrophied secondary interstitial cells. In contrast, cystic follicles in EV‐treated rats are fewer in number, but much larger than those in the E2‐implanted animals. The cystic theca and the secondary interstitial cell clusters are also far less extensive in the EV‐induced poiycystic ovary. These and other differences between the two types of PCO indicate that they are produced by fundamentally different morphogenic mechanisms. The cystic ovary produced by the E2 implants is similar in appearance to that seen in the human Stein‐Leventhal condition, and thus provides a new model for the study of cystic ovarian disease.
An HRP study of location of the rabbit palatopharyngeal motoneurons and peripheral course of their axons
Authors: Kitamura Seiichiro , Ogata Kimio 
Published: February 2005

AbstractThe location of the rabbit palatopharyngeal motoneurons and the peripheral course of their axons were investigated with intramuscular injection of HRP either in the normal animal or in conjunction with intracranial severing of the vagal rootlets. Labeled palatopharyngeal motoneurons were ipsilaterally located within a subdivision of the nucleus ambiguus which is formed by a compact arrangement of the smallest neurons of the nucleus and situated in the rostral half of the nucleus. We named that subdivision the compact cell group (CoG). The labeled motoneurons occupied the caudal half of the CoG at a level from about 500 to 1,900 μm rostral to the obex. Labeling was completely abolished by severing the vagal rootlets, indicating that the axons of the palatopharyngeal motoneurons traversed the vagal rootlets.
Araldite F as injection material for quantitative morphology of cerebral vascularization
Authors: Van Der Zwan Albert , Hillen Berend 
Published: February 2005

AbstractThis study deals with the applicability of Araldite F as injection medium for quantitative morphology of the cerebral vascularization. The physical properties of the plastic that are essential for obtaining optimal results have been determined and tested by injection into the cerebral vessels of ten dog brains and five human brains. The dynamic viscosity (at 20°C) of the plastic is 1.5 times that of blood. The polymerization time (±45 min) is long enough to fill the whole vascular tree in a large organ such as the human brain. The plastic shows minimal volume shrinkage (3.90% ± 0.05%), and the final cast is suitable for scanning electron microscopy (SEM) investigation after corrosion and histological morpho‐metrical examination after embedding in 2‐hydroxyethyl‐methacrylate (GMA). Special attention has been paid to the conditions under which injection of Araldite F into the cerebral arteries must take place to obtain the most accurate quantitative data on cerebral vascularization and vascular area distribution. Simultaneous injection of the major cerebral arteries of fresh autopsy material, after having removed blood clots by perfusing Kabikinase, is recommended.
Adaptation of diaphyseal structure to aging and decreased mechanical loading in the adult rat: A densitometric and histomorphometric study
Authors: Li Xiao Jian , Jee Webster S. S. 
Published: February 2005

AbstractNine‐month‐old female rats were subjected to right hindlimb immobilization or served as controls for 0, 2, 10, 18, and 26 weeks. They were double‐labeled with bone markers prior to sacrifice. Experimental unloading was produced by immobilizing the right limb against the abdomen with an elastic bandage. Single‐photon absorptiometry was performed on the intact femurs; static and dynamic histomorphometry were performed on 20‐μm thick toluidine blue‐stained, undecalcified cross sections of the tibial shafts. Changes in the continuously immobilized tibiae were compared to those in both tibiae of age‐matched controls.Unloading shut off nearly all periosteal bone formation and accelerates bone marrow expansion over that which occurs in age‐related controls. The effects of unloading appeared to be mediated by recruiting fewer osteoblasts which showed inhibited activity. Furthermore, unloading increased endocortical percentage eroded surface. These histological changes lowered cortical bone mass by inhibiting diaphyseal cross sectional expansion and enlarging the bone marrow cavity. The results support Frost's suggestion that decreased mechanical usage depresses bone modeling‐dependent bone gain by decreasing activation of modeling in the formation mode. It also stimulates bone remodeling‐dependent bone loss by increasing activation of remodeling in the resorption mode.
Expression of a fast myosin heavy chain mRNA in individual rabbit skeletal muscle fibers with intermediate oxidative capacity
Authors: Dix David J. , Eisenberg Brenda Russell 
Published: February 2005

AbstractIn situ hybridization (ISH) of myosin heavy chain (MHC) mRNA, immunofluorescent detection of MHC protein, and oxidative enzyme histochemistry were performed on the same fibers in serially sectioned rabbit skeletal muscle. By combining these three techniques quantitatively, on a fiber‐by‐fiber basis, fibers that expressed mRNA complementary to a fast MHC cDNA pMHC24–79 of unknown subtype (Maeda et al., 1987) were classified into fiber types with respect to slow myosin expression and oxidative capacity. As expected, slow fibers had low hybridization to pMHC24–79. Fast fibers were divided into three subtypes. mRNA from the low oxidative fibers (fast‐glycolytic, IIB) did not hybridize with pMHC24–79. Fast fibers whose mRNA hybridized best to pMHC24–79 were mainly in the intermediate range of oxidative capacity (probably IIX). The fast fibers with the highest oxidative capacity had low hybridization to this MHC mRNA (probably IIA). Thus, pMHC24–79 was identified as a clone of a fast isomyosin, tentatively designated as the fast IIX with intermediate oxidative capacity. The expression of more than a single species of fast and slow isomyosin mRNAs in classically defined fiber type was considered in interpreting these results.
Muscle spindle ultrastructure revealed by conventional and high‐resolution scanning electron microscopy
Authors: Patten Robert M. , Ovalle William K. 
Published: February 2005

AbstractMuscle spindles in the tenuissimus muscle of mature golden Syrian hamsters were examined by conventional and high‐resolution scanning electron microscopy (HRSEM). For conventional SEM, entire muscles were first fixed in 2.5% buffered glutaraldehyde. Spindles were then isolated with a dissecting microscope under darkfield illumination and postfixed in 1.0% OsO4. Some spindles were treated with 8 N HCl at 60°C to clearly expose intrafusal fiber surfaces once the outer capsular sheath was mechanically disrupted. Preparation for HRSEM included aldehyde/osmium fixation and freeze‐cleavage in liquid N2. The cytosol and certain cellular elements were also selectively extracted by immersion in 0.1% OsO4 for varying time intervals. In these preparations, the capsular sleeve showed a multilayered pattern of vesicle‐laden cells with variant surface topography in different regions, including filopodia and small bristle‐like surface‐projections. An interlacing three‐dimensional network of collagen fibrils intervened between the capsular lamellae. Within the spindles, sensory and fusimotor nerve endings closely adhered to the outer surfaces of intrafusal fibers. Sensory nerve terminals were enveloped by a prominent external lamina, and those that were cleaved open contained a plethora of elongated mitochondria that ran parallel with the longitudinal axis, along with vesicles, axoplasmic filaments, and lysosomes. Multiple adhesion sites between the sensory nerve membrane and the underlying sarcolemma of the intrafusal fiber were also observed in select regions. Fusimotor nerve endings were covered externally by processes of Schwann cells and their axoplasm was filled with a multitude of cellular organelles and synaptic vesicles. Dilated cisternae of the sarcoplasmic reticulum and numerous mitochondria were, in addition, observed below the postjunctional sarcolemma at the neuromuscular interface. The methodology used in this study provides a novel view of the exquisite three‐dimensional architecture of this complex neuromuscular receptor.