Post-natal bone physiology

Post-natal bone development is characterized by substantial longitudinal bone growth and changes in skeletal size and shape. Bone is in a dynamic process of continuous remodeling which helps to regulate calcium homeostasis, repair micro-damage to bones from everyday stress, and to shape the skeleton during growth. Bone growth is regulated by systemic hormones and locally generated factors. Understanding their mechanisms of action enables us to obtain a better appreciation of the cellular and molecular basis of bone remodeling and could therefore be valuable in approaches to new therapies. This article will review molecular and cellular control of skeletal growth in the post-natal period, the physiology of each bone cell with their systemic and local regulators, as well as the physiology of bone remodeling.     

血常规在感染判定的价值

感染性疾病是儿科最常见的疾病之一,是由病原体侵入机体引起的局部组织损伤或全身炎性反应。儿童免疫力低下,病情进展快,需早期诊断及时治疗。各种感染性疾病的临床症状无显著特异性,尤其在早期阶段,而作为诊断金标准的病原学检测,因对检验环境要求高、耗时长、阳性率低及易污染等缺点,不利于早期诊断。血常规是临床上最基本及廉价易行的检验项目,具有操作简单、用时短等优点,主要检测白细胞、红细胞、血小板等血液有形成分的质和量及形态变化,特别是白细胞检测对感染性疾病的早期诊断、鉴别诊断,评估严重程度及治疗效果均具有重要价值,是目前儿科临床诊断感染性疾病的首选辅助检查方法。     

A Study of Changes in Uterine Leucocytes During Early Pregnancy in the Mouse-vole Interspesific Pregnancies

Mouse and vole embryos were allogeneically and xenogeneically transferred into pseudopregnant CD.1 and immunodeficient (seid)female mice,and we investigated the distribution of uterine leucocytes cells in the implantation sites on days 5,6,and 7 of pregnancy. Maerophages were evenly distributed in the endometrium on days 5-7.Neutrophils were rarely seen on days 5-7,but lymphocytes were found throughout the endometrium,often in groups associated with glands or the luminal epithelium.The number of uNK cells increased markedly at the mesometrial uriangle and the outer decidual area in the CD-1 uteri containing vole embryos;by contrast,seid uteri having vole embryos showed almost the same number as those having mouse embryos.Mast cells were present in large numbers at the myometrium,but rarely in the decidua in all types of pregnant uteri.Cells at the myometrium were more numerous in xenogeneic than in allogeneic transfer.Maay mast cells appeared in the inner decidua where xenogeneically transferred vole embryos were dead and aborted.These results suggest the possibility that uterine leucocytes mediate various immunological events in the mouse-vole interspesific pregnancies.     

Glicentin-containing cells in intestinal metaplasia,adenoma and carcinoma of the stomach

Summary Glicentin-containing cells (Glic. cells) in intestinal metaplasia, adenoma and carcinoma of the stomach were examined using immunohistochemical techniques. Glic. cells first occurred in the gastric mucosa of the transitional area between metaplastic and intact gastric glands. They frequently showed hyperplasia or micronoduli in the budding area of the deeper metaplastic glands, but in completely intestinalized mucosa these endocrine cells decreased remarkably. Gastric adenomas with mild dysplasia had a good number of glicentin-immunoreactive cells which were located in the deeper adenoma glands. Gastrin- and somatostatin-positive cells were also detected in the adenomas. The incidence of glicentin-positive tumor cells was significantly higher in well differentiated adenocarcinoma than in poorly differentiated adenocarcinoma. Among the seven cases of scirrhous argyrophil cell carcinoma, three showed glicentin- and glucagon-immunoreactivity in the same area of the tumor. These findings suggest that the selective increase of Glic. cells in intestinal metaplasia may be closely related to the development of gastric adenoma. Glicentin positive tumor cells in gastric carcinomas can be regarded to be an expression of intestinal or fetal markers.     

Endocrine cells in the anal canal

Summary Endocrine cells are normal inhabitants of the anal canal. While numerous endocrine cells are distributed throughout anal ducts and crypts, few are dispersed in the anal transitional zone. All these cells were characterized as serotonin-storing cells, and this endocrine profile is quite distinctive from that of adjacent mucosae. Rectal epithelium contains serotonin, somatostatin, enteroglucagon, BPP and HPP immunoreactive cells; endocrine cells are lacking in the pectinal folds and perianal skin. It is suggested that this distinctive hormonal profile may be regarded as a specific marker of this anal territory. The same pattern is found in the fetal transitional lining of anal canal.Evidence of serotonin-storing cells in the transitional epithelium of anal glands and crypts and in the ATZ epithelium, reinforces the homology between these linings and urothelium. The presence of a similar fetal epithelium implies that ATZ epithelium in adults is not necessarily metaplastic. All derivatives of the cloaca may therefore share the same endocrine profile.     

Cell populations of the ganglion cell layer: displaced amacrine and matching amacrine cells in the pigeon retina

Summary The proportion and size distribution of ganglion and non-ganglion cells in the ganglion cell layer of different areas of the pigeon retina was examined in whole-mounts of the retina by retrograde axonal transport of horseradish peroxidase (HRP) from large brain injections. A maximum of 98% of cells were labelled in the red field and a maximum of 77% in the peripheral yellow field. Unlabelled cell bodies were 30% smaller than labelled ganglion cells and had a mean diameter of 6.2 m and a size range of 4 to 9 m. The morphology of cells in the ganglion cell layer was examined by Golgi staining of retinal whole-mounts. Small glia, displaced amacrine and ganglion cells were found. Displaced amacrine cell bodies were about 30% smaller than ganglion cells and their size distribution was similar to the unlabelled cells in HRP preparations. Displaced amacrine cells had small rounded cell bodies (mean diameter 6.2 m) increasing in size with eccentricity, and a unistratified dendritic tree of fine, nearly radial, varicose dendrites in sublamina 4 of the inner plexiform layer. They had elliptical dendritic fields (mean diameter 66 m) aligned parallel to the retina's horizontal meridian. A population of amacrine cells was found with somas at the inner margin of the inner nuclear layer and soma and dendritic morphology matching those of displaced amacrines. These amacrine cells had unistratified dendritic trees at the junction of sublaminae 1 and 2 of the inner plexiform layer. Pigeon displaced amacrine cells and their matching amacrines are similar to starburst cells of the rabbit retina. They may participate in on and off pathways to ganglion cells and their lamination suggests that they are cholinergic.     

Absence of reoxygenation damage in isolated heart cells after anoxic injury

Cultured adult cardiac myocytes were exposed to anoxia under substrate-free conditions and then reoxygenated. When comparing the oxygen deficient organ to the anoxic cell culture, we see that metabolic changes in the latter system proceed in a similar, yet prolonged manner, as in arrested hearts. Release of cytosolic enzymes starts with minor energetic disturbances and proceeds closely correlated to the actual ATP level. Below 2 mol ATP/g_ww, an increasing number of cells becomes irreversibly damaged, above this level, 30 min reoxygenation leads to extensive recovery of the whole preparation. The results indicate that leakage of cytosolic enzymes during the early stage of anoxia is due to a gradual protein release from the individual cells and is related to reversible membrane alterations. Reoxygenation does not induce changes considered typical of the oxygen paradox. Since mechanical cell-cell interactions are absent in this model, it is suggested that aggravation of tissue damage in heart tissue reoxygenated late is mainly caused by mechanical forces.     

Patch-clamp study of rubidium and potassium conductances in single cation channels from mammalian exocrine acini

Single-channel current recordings were carried out on excised inside-out patches of baso-lateral plasma membrane from exocrine acinar cells. The mouse pancreas and submandibular gland as well as the pig pancreas were investigated.In the mouse pancreas the voltage-insensitive Ca²⁺-activated cation channel was studied. Single-channel current-voltage (i/v) relationships were studied in symmetrical Rb⁺-rich solutions and in asymmetrical Rb⁺/Na⁺ and Na⁺/Rb⁺ solutions. In all cases the i/v relations were linear and had the same slope representing a single-channel conductance of about 33 pS which is identical to that previously obtained with symmetrical Na⁺ solutions or asymmetrical Na⁺/K⁺ solutions.In the mouse submandibular gland and the pig pancreas the voltage and Ca²⁺-activated K⁺ channel was studied. The outward currents observed after depolarization in the presence of quasi-physiological Na⁺/K⁺ gradients were immediately abolished when all the K⁺ in the bath fluid was replaced by Rb⁺ (bath fluid in contact with inside of plasma membrane). This effect was immediately and fully reversible upon return to the high K⁺ solution.The voltage and Ca²⁺-activated K⁺ channel was also studied in asymmetrical K⁺/Rb⁺ and Rb⁺/K⁺ solutions. In the first case inward (K⁺) currents could be observed but not outward (Rb⁺) currents, while in the other case inward (Rb⁺) currents could not be seen whereas outward (K⁺) currents were measured. The current-voltage relationships were approximately linear and the null potential was close to 0 mV in both situations. In contrast the null potential for current through the K⁺ channel in the presence of asymmetrical Na⁺/K⁺ or Li⁺/K⁺ solutions was about –70 mV and with reversed gradients about +60 mV.Outward K⁺ currents of reduced size (through the voltage and Ca²⁺-activated K⁺ channel) could be observed when the bath fluid contained 75 mM K⁺ and 75 mM Rb⁺, but not (in the same membrane patches) when 150 mM Rb⁺ and no K⁺ was present.It is concluded that the large voltage- and Ca²⁺-activated K⁺ channel has an extremely low Rb⁺ conductance. It is possible, however, that the permeability for Rb⁺ may be about the same as for K⁺. The voltage-insensitive Ca²⁺-activated cation channel does not discriminate between K⁺ and Rb⁺.     

Properties of visual cortical cells of the intact and the deafferented hemisphere of unilateral optic tract sectioned acute and chronic adult cats

Summary Single unit recording from visual cortex areas 17 and 18 and in the border region between them was performed on adult cats with unilateral optic tract section (OTX) either on the day of the operation (acute) or three to six months postoperatively (chronic). Visual activity from both hemispheres was analyzed with respect to the responsiveness level, the ocular dominance distribution and selectivity to orientation and direction. The results showed almost a complete absence of visual responsiveness in the deafferented hemisphere and a considerable reduction of responsiveness in the intact hemisphere. Following surgery an increase in visually responsive cells was found in the intact hemisphere as postoperative recovery continued. In addition, a reduction in the proportion of cells selective for orientation and direction was also found in the intact hemisphere of the OTX animals as compared to the control cats. Furthermore, cortical binocularity was not affected in the intact hemisphere of all OTX cats.We conclude that an almost total absence of interhemispheric callosal transfer of visual functions from the intact to the deafferented hemisphere is induced as a result of the unilateral OTX in adult cats. Moreover, the fact that the absence of cortical binocularity in the hemisphere receiving direct geniculate input was not disrupted, indicates the absence of callosal transfer from the deafferented to the intact hemisphere.     

A physiologically active kainic acid-preferring receptor in chicken retina

Neurotoxicity induced by intravitreal injections of kainic acid in the chicken retina was effectively antagonized by piperidine 2,3-dicarboxylic acid and to a lesser extent D-gamma-glutamylglycine. 2-Amino-5-phosphonovaleric acid and glutamic acid diethyl ester were much less effective antagonists. These effects probably result from interactions with a kainic acid-preferring receptor localized on the OFF-centre bipolar cells. Piperidine 2,3-dicarboxylic acid and D-gamma-glutamylglycine also blocked selectively the OFF-responses of ganglion cells while glutamic acid diethyl ester was without effect. 2-Amino-5-phosphonovaleric acid rapidly blocked ON and, much more slowly, OFF-responses. These results are consistent with a role for kainic acid-preferring receptors located on the OFF-centre bipolar cells in chicken retina in physiological transmission between photoreceptors and the OFF-centre bipolar cells.