Myofibril and sarcoplasmic reticulum changes during muscle development: Activity vs inactivity

• 1.1. The purpose of this study was to determine whether biochemical changes of skeletal muscle that occur as a result of exercise in young rats persist into adulthood.
• 2.2. Littermates (10 days old) were assigned to a 3, 6 and 12 week control or training group. In addition, a rest-exercise group (R-E) and exercise-rest (E-R) group were included.
• 3.3. The rest-exercise and exercise-rest rats were maintained for the 12 weeks with the first 6 weeks being either rest or exercise and the condition reversed during the last 6 weeks of the experiment.
• 4.4. Myofibril ATPase activity of rat plantaris increased from the 10d to 12 week animals (P < 0.05). As anticipated, training resulted in a lowered activity at 6 and 12 weeks compared to controls.
• 5.5. The Ca²⁺ uptake and Ca²⁺-ATPase activity of the sarcoplasmic reticulum followed a similar pattern.
• 6.6. With regard to the exercise-rest rats, the myofibril and SR ATPase activities at 12 weeks were comparable to the 12 weeks control rats.
• 7.7. The rest-exercise group approximated the 12 week training group with regard to myofibril and SR ATPase activities (P > 0.05).
• 8.8. The results suggest that the training adaptations that occur during development of skeletal muscle return to normal, when training ceases in the adult rat.
• 9.9. Furthermore, animals that started to train prior to puberty do not have a greater capacity to adapt than animals which initiated training during adulthood.

     

Melanocyte subpopulation turnover during the human hair cycle: an immunohistochemical study

The human hair cycle is characterized by successive phases of growth and involution that imply tissue regression and regeneration. As a consequence, the hair melanin unit has to be renewed in a cyclic manner. Actually, the behavior of human hair follicle melanocytes throughout the hair cycle has been poorly studied. Thus, the origin of melanocytes present in the bulb after human hair regeneration is still not clarified, and neither are the events that control the melanin biosynthesis activity in the human hair bulb. In this study, we showed at the cellular level that in human pigmented hair follicles, the expression of tyrosinase and tyrosinase-related protein-1 (TRP-1) was detectable during the anagen phases III/IV through VI, only in those melanocytes which were located in the bulb. During the catagen phase, the two evaluated melanogenic enzymes were detectable no more, although melanocytes were still present in the preceding bulbar area. The epithelial column of catagen follicles and the capsule of telogen follicles also contained inactive melanocytes as evidenced by pMel-17 labeling. At the induction of a new anagen hair follicle, some melanocytes were committed to cell division, but only when located in the nascent bulb close to the dermal papilla. Our results emphasize the close relationship between melanogenesis and the hair cycle and suggest that in humans, melanogenesis is restricted to anagen hair follicles not because of the regulation of tyrosinase activity, but because of melanogenic enzyme expression, e.g., tyrosinase and TRP-1. Furthermore, the fact that in the newly developing anagen hair follicles, cell-division commitment and tyrosinase and TRP-1 expression were observed in melanocytes only when located in the nascent bulb suggests a highly regio-specific melanocyte stimulation in early the anagen phase.     

Merosin deficient congenital muscular dystrophy: Clinical,neuroimaging and immunohistochemical study of 8 Egyptian pediatric patients

Congenital muscular dystrophies (CMD) are a group of heterogeneous inherited autosomal recessive disorders characterized by muscular weakness, hypotonia and contractures. The Merosin Negative CMD (MNCMD) is considered to be the most severe form and is usually associated with white matter abnormalities as seen with brain imaging. Merosin is also expressed in the nervous system and its deficiency could affect its development. This article describes the clinical picture, muscle biopsy findings and neuroimaging abnormalities of eight Egyptian Pediatric patients with the clinical presentation of merosin negative congenital muscular dystrophy. The leading clinical presentation in almost all patients was severe hypotonia, muscular weakness and failure to achieve motor developmental milestones, only Case 2 walked at 2 years of age. Mentality was normal in most patients with exception of Case 2 in whom scholastic achievement was poor and was associated with behavior abnormality. Serum Creatine kinase ranged from moderate to severe elevation, 536–3563 U/L, Electromyography demonstrated a myopathic pattern in all patients. Brain MRI showed extensive demyelination of the cerebral white matter in 6/8 patients with extension to cerebellar demyelination in Case 5. 5/8 patients underwent muscle biopsy for which immunofluorescence staining for merosin demonstrated complete deficiency of laminin α2 in Case 5 & partial deficiency of laminin α2 in Case 2.This report demonstrates the utility of Immunofluorescence staining as a guide to confirm the diagnosis of MDCMD especially when molecular diagnosis is not available.     

Fibronectin distribution during lymph node development in guinea pig: an immunohistochemical study

We carried out an immunohistochemical study on mesenteric guinea pig lymph nodes, from the 10th day prepartum till the 26th day postpartum, to assess the role of fibronectin in their organization during development. This glycoprotein is diffusely distributed in embryonic lymph nodes, suggesting a primer function during organogenesis. After birth, in fact, it is less widespread and is mainly localized around sinuses and vessels. Our data, supporting the important role of this glycoprotein during lymph node organization, are in agreement with the results obtained in other tissues and organs.     

Renal leiomyoma: an immunohistochemical, ultrastructural and comparative genomic hybridization study

Renal leiomyoma is a rare neoplasm. We report such a case in a 57-year-old Japanese woman who was found to have a mass in the left kidney. The histological examination disclosed the proliferation of spindle cells showing a benign appearance. Entrapped tubular cells were observed in the peripheral area of the tumor. The immunohistochemical examination of spindle neoplastic cells showed a positive reaction for alpha smooth muscle actin, h-caldesmon, l-caldesmon, calponin, muscle actin, myosin and desmin. Additionally, the ultrastructural examination of the tumor showed membrane caveolae and myofilaments in the cytoplasm. This tumor was considered to show a differentiation into smooth muscle cells. The comparative genomic hybridization of the tumor detected the combined losses of chromosomes 4, 6, 12 and 14 which has not been previously described in renal tumors. Finally, the immunohistochemical panel of smooth muscle markers and ultrastructural and genetic study may be useful in diagnosing renal leiomyoma.     

Integrins during evolution: Evolutionary trees and model organisms

The integrins form a large family of cell adhesion receptors. All multicellular animals express integrins, indicating that the family evolved relatively early in the history of metazoans, and homologous sequences of the component domains of integrin α and β subunits are seen in prokaryotes. Some integrins, however, seem to be much younger. For example, the αI domain containing integrins, including collagen receptors and leukocyte integrins, have been found in chordates only. Here, we will discuss what conclusions can be drawn about integrin function by studying the evolutionary conservation of integrins. We will also look at how studying integrins in organisms such as the fruit fly and mouse has helped our understanding of integrin evolution-function relationships. As an illustration of this, we will summarize the current understanding of integrin involvement in skeletal muscle formation.     

Substance P and hydra: an immunohistochemical and physiological study

1. The distribution of substance P-like immunoreactivity was studied in Hydra attenuata using the peroxidase-antiperoxidase technique. 2. Positive immunoreactivity was observed in ectodermal nerve cells and fibers as well as in nematoblasts at various stages of differentiation. 3. Administration of synthetic substance P to regenerating hydra did not affect regeneration rates. Exogenous substance P administration stimulated tentacle contraction and nematocyst displacement within battery cells. 4. It is suggested that substance P acts on the contractile apparatus of Hydra tissues.     

Calcifying epithelial odontogenic tumor: an immunohistochemical case study

Calcifying epithelial odontogenic tumor (CEOT) is a rare benign odontogenic tumor. A case of CEOT in a 25-year-old female is presented here. Histologically, the case showed sheets of polyhedral epithelial cells with deep eosinophilic cytoplasm and prominent nuclei. Nuclear pleomorphism and hyperchromatism were evident. Globules of amyloid-like material among the tumor cells were prominent. Also found was a small area demonstrating a cribriform pattern. Immunohistochemical studies with antibodies against basement membrane proteins (laminins 1 and 5, collagen type IV and fibronectin), pan-cytokeratins AE1/AE3, vimentin, S-100 protein and CD 1a were performed. Tumor cells expressed laminins 1 and 5, fibronectin, cytokeratins and vimentin. The amyloid-like material was not reactive to all antibodies examined. A number of dendritic cells among sheets of tumor cells were revealed with strong staining for S-100 protein and CD 1a. These dendritic cells are likely to be Langerhans cells. Hence, immunohistochemistry is a useful method to study the variant of CEOT.     

Vascular and cellular events in post-mastectomy seroma: an immunohistochemical study

This study aimed to describe the vascular and cellular histopathological changes that occurred in post-mastectomy seroma in an animal model. Unilateral mastectomies were conducted on 45 female albino rabbits. On day seven, the skin flap and the underlying tissues of the mastectomy regions were dissected and processed for histopathological examination using immunohistochemical staining of the T- and B-lymphocytes and macrophages (CD3, CD20, and CD68 respectively), and the vascular endothelia. The post-mastectomy regions in the seroma group showed a large number of inflammatory cells and newly formed blood vessels that lost the integrity of their endothelial cell linings, as revealed by the von Willebrand factor staining, as well the basement membrane, as revealed by the histochemical stain. The post-mastectomy seroma beds showed many CD3 and CD20+ve lymphocytes and CD68+ve macrophages. These macrophages were producing angiogenic factors, resulting in the persistent and continuous formation of new blood vessels. These new blood vessels were defective and represented an underlying cause of seroma formation.     

Intrinsic neurons in the rat ovary: an immunohistochemical study

Previous studies have shown the presence of neuronal perikarya in the primate ovary, but not in the ovary from Sprague-Dawley rats. We report here that while such intrinsic neurons are indeed absent in this strain of rats, they can be visualized in the ovary from Wistar rats. The neurons, identified by their morphology and by the expression of NeuN (a neuron-specific nuclear protein), were detected at all postnatal intervals examined, from 14 h after birth to 50 days of age. While they were present in the ovarian hilum and medulla at all ages studied, neurons first appeared in the ovarian cortex during the juvenile period (postnatal days 10-20). In all cases, the size of the neuronal soma increased significantly during prepubertal development, reaching maximal values before puberty. Some neurons were catecholaminergic, as indicated by their content of immunoreactive tyrosine hydroxylase (TH), the rate-limiting enzyme of catecholamine biosynthesis. Some showed neuropeptide Y (NPY) immunoreactivity. TH-positive neurons were seen either in isolation or clustered in ganglion-like structures in both the ovarian cortex and medulla. These results indicate that ovarian neurons are not present in all strains of rats, but when present, the chemical phenotype of some of them is of a sympathetic nature, similar to that described in primates.     

Morphologic and morphometrical study of the muscle spindle in muscular dystrophy

OBJECTIVE: To determine the morphologic and the morphometrical features of spindles in biopsies of patients with different types of muscular dystrophy and investigate the possible involvement of the spindle in the pathologic process of these diseases. STUDY DESIGN: The following variables were studied in biopsy specimens from 10 patients with Duchenne or Becker dystrophy, 9 with limb-girdle dystrophy, 3 with congenital dystrophy and 3 with facioscapulohumeral dystrophy: diameter and area of spindle; thickness of the capsule; number, diameter and area of intrafusal fibers; and number and area of nuclei. RESULTS: The statistical evaluation of the data showed significant differences regarding the thickness of the capsule, which was greater in patients than in controls, while the diameter and the area of the fibers were all smaller in patients than in controls. The area of nuclei of fibers was increased; this was a common feature for all types of muscular dystrophy. CONCLUSION: These findings indicate that the spindle possibly participates in the pathologic process of different types of muscular dystrophies.     

Innervation of the canine mammary gland: an immunohistochemical study

The distribution of peptidergic nerves in canine mammary tissues was studied by immunohistochemical techniques. In addition, the general and the noradrenergic innervations were demonstrated using protein gene product 9.5 and tyrosine hydroxylase immunoreactivities as markers, respectively. Tissue specimens from the caudal mammary glands were obtained from adult, non-lactating, female dogs. The overall innervation of the mammary gland tissue was sparse and primarily associated with the arterial vasculature. Nerve fibres positive for protein gene product 9.5 were rarely found in the secretory parenchyma. The nipple was not richly innervated, although it displayed a greater amount of nerve fibres than the mammary parenchyma. Nerve fibres supplying nonvascular structures of the nipple expressed immunoreactivity for the sensory neuropeptides calcitonin gene-related peptide, substance P and neuropeptide K, but not for vasoactive intestinal peptide, peptide histidine isoleucine and C-flanking peptide of neuropeptide Y. Somatostatin immunoreactivity was not detected in mammary gland tissue. Our results indicate that the innervation of the canine mammary gland is mainly affiliated with the vasculature and comprises peptidergic nerves which may be involved in the regulation of local blood flow. The presence of sensory neuropeptides in nerves supplying the mammary nipple suggest that these peptides may play a role in the afferent pathway of the milk ejection reflex.     

Collagenase-3 expression in periapical lesions: an immunohistochemical study

Collagenase-3 (matrix metalloproteinase-13) is a metalloproteinase (MMP) that is associated with bone lesions and exhibits variable expression patterns in odontogenic cysts; it may play a role in regulating focal proliferation and maturation of jaw cyst epithelium. We studied the localization, staining intensity and distribution of collagenase-3 in 13 periapical granulomas with epithelium, 16 periapical granulomas without epithelium and 10 radicular cysts using archived formalin fixed, paraffin embedded tissues. A monoclonal antibody against human collagenase-3 was used to evaluate its expression. Immunohistochemical staining intensities of collagenase-3 in all periapical lesions were (?), 4 (10%); (+), 1 (3%); (++), 22 (56%) and (+++), 12 (31%); differences were not statistically significant. Immunohistochemical distribution of collagenase-3 in epithelial cells was (?), 17 (44%); (+), 17 (44%); (++), 5 (13%); in fibroblasts it was (?), 8 (20%); (+), 23 (59%); (++), 8 (21%); in plasma cells it was (?), 7 (18%); (+), 22 (56%); (++), 10 (26%); in macrophages it was (?), 7 (18%); (+), and 15 (38%); and (++), 17 (44%). Statistically significant differences were found in epithelial cells (p = 0.00) and fibroblasts (p = 0.02), whereas differences were not statistically significant for plasma cells and macrophages. Collagenase-3 may play a role in the conversion of a periapical granuloma with epithelium to radicular cyst. MMP's influence not only epithelial rest cell migration, but also invasion of various stromal cells into granulomatous tissue.     

Regulated changes in chondroitin sulfation during embryogenesis: an immunohistochemical approach

Chondroitin sulfate proteoglycans, which represent the main class of nonfibrous macromolecules found in the extracellular matrix of connective tissues, have been implicated in the control of a variety of cell activities during ontogenesis. The respective contributions of the chondroitin sulfate chains and of the protein moiety of the proteoglycan in morphogenesis and cytodifferentiation are not known. In this context, monoclonal antibodies identifying specific chondroitin sulfate chains are interesting new tools. A panel of well characterized monoclonal antibodies recognizing distinct epitopes present only in chondroitin sulfate chains was used in conjunction with immunohistochemical techniques for the purpose of identifying and mapping chondroitin sulfate isoforms during development in the mouse and rat fetus. Expression of chondroitin sulfate isoforms occurred in the tissues according to specific spatio-temporal patterns, suggesting that chondroitin sulfates differing in sulfation position and degree perform distinct functions in development.     

Taurine in toad brain and blood under different conditions of osmolality: An immunohistochemical study

The concentrations of taurine in blood and brain regions of the toadBufo boreas have been measured. Most of these values are considerably lower than those found in mammals. Using an antibody prepared against conjugated taurine, the distribution of taurine in three brain regions of the toad has been visualized. The possible osmoregulatory functions of taurine have been investigated by making toads hyper- or hypo-osmotic in vivo. Induction of hypoosmolality is accompanied by a massive taurine tide in blood plasma, but has no immediate effects upon the taurine concentrations in the brain areas studied. However, histochemical visualization indicates a marked redistribution of taurine between cellular components and extracellular space of brain tissues. This may indicate that taurine has an osmoregulatory function in brain tissue under hypo-osmotic conditions. Hyperosmolality results in no elevation of the taurine concentration in blood plasma of toads, but rather in a very gradual decline of total plasma taurine content over a prolonged time period. Histochemical studies reveal little change in frontal cortex after 1 hour but deeper staining of many neurons in optic lobe accompanied by greater staining in the extracellular fluid. By 3 hours there is a depletion of taurine from all compartments of cerebral cortex tissues. No evidence of any prolonged direct osmoregulatory role for taurine is indicated under hyperosmotic conditions. A possible indirect osmoregulatory function of taurine is discussed.Special issue dedicated to Dr. Claude Baxter.