Retinal disease in the C3 glomerulopathies and the risk of impaired vision

Background: Dense deposit disease and atypical hemolytic uremic syndrome are often caused by Complement Factor H (CFH) mutations. This study describes the retinal abnormalities in dense deposit disease and, for the first time, atypical haemolytic uremic syndrome. It also reviews our understanding of drusen pathogenesis and their relevance for glomerular disease. Methods: Six individuals with dense deposit disease and one with atypical haemolytic uremic syndrome were studied from 2 to 40 years after presentation. Five had renal transplants. All four who had genetic testing had CFH mutations. Individuals underwent ophthalmological review and retinal photography, and in some cases, optical coherence tomography, and further tests of retinal function. Results: All subjects with dense deposit disease had impaired night vision and retinal drusen or whitish-yellow deposits. Retinal atrophy, pigmentation, and hemorrhage were common. In late disease, peripheral vision was restricted, central vision was distorted, and there were scotoma from sub-retinal choroidal neovascular membranes and atypical serous retinopathy. Drusen were present but less prominent in the young person with atypical uremic syndrome due to a heterozygous CFH mutation. Conclusions: Drusen are common in forms of C3 glomerulopathy caused by compound heterozygous or heterozygous CFH mutations. They are useful diagnostically but also impair vision. Drusen have an identical composition to glomerular deposits. They are also identical to the drusen of age-related macular degeneration, and may respond to the same treatments. Individuals with a C3 glomerulopathy should be assessed ophthalmologically at diagnosis, and monitored regularly for vision-threatening complications.     

大颗粒小泡非突触部位的胞吐——论神经肽释放的另一种形式

本文在以前的工作基础上,进一步用电镜及免疫细胞化学方法,研究了大颗粒小泡非突触部位胞吐作用。实验结果表明,切除大鼠刚髭部皮肤1—24小时之后,术侧延髓后角浅层大颗粒小泡胞吐比对照侧明显增多(P<0.01),术后3—9天复又下降(近似对照动物),术后14—15天又急剧上升(P<0.01)。这些胞吐大部分出现于延髓后角浅层四种轴突终末的非突触部位,少最也发生于树突及轴突中。从术后第6天开始,术侧P物质明显减弱,而甲硫-脑腓肽略有增强。研究结果提示;1)后角浅层胞吐增多,P物质下降及脑腓肽增高,反映了中枢内不同神经元对去传入神经的功能调整作用;2)大颗粒小泡在非突触部位释放神经肽,弥散地作用于远距离的受体,可能起着神经调制物的作用。     

The nature of breast dense core granules: uranaffin reactivity

In this study breast tissue that contained ultrastructural dense core granules has been examined from 24 patients. The possible neuroendocrine characteristics of the granules were studied using the uranaffin reaction and an ultrastructural argyrophil stain. The tissue included 15 breast carcinomas and nine benign samples. Two types of breast dense core granules can be distinguished on the basis of intracellular distribution patterns and histochemical reactivity. Type I dense core granules are the most common and they were found subluminally distributed in non-pathological tissues and benign lesions as well as carcinomas. They were uranaffin-negative and are unlikely to be of endocrine nature. Type II dense core granules were found only in four carcinomas, where they occurred abundantly throughout the cytoplasm. These granules were uranaffin-positive and argyrophilic and thus exhibited characteristics consistent with neuroendocrine structure.     

Demonstration of adherence properties of Porphyromonas gingivalis outer membrane vesicles using a new microassay

Vesicles made by Porphyromonas gingivalis possess several biological activities, including the ability to adhere to oral surfaces and to bacteria. In this study, a new and simple method was developed to measure the adherence capability of outer membrane vesicles from P. gingivalis . Vesicles were conjugated to fluorescent microspheres (0.7 μ) and added to wells of a Teflon-coated microscope slide previously covered with a variety of soluble ligands. After incubation and washes, the number of fluorescent microspheres per microscopic field were counted. Vesicle-coated microspheres attached best to gelatin (<200 per field), whereas other compounds (such as fibronectin, fibrinogen, collagen and laminin) provided moderate attachment, and no attachment was observed to bovine serum albumin. Adherence to any of the tested ligands was not observed when fluorescent micro-spheres were conjugated to bovine serum albumin or lipopolysaccharides from P. gingivalis. The adherence of vesicle-coated microspheres to ligands was not significantly affected when the pH of the reaction mixture was between 4 and 10. None of the tested carbohydrates lowered the attachment capability of vesicle-coated microspheres to substrates. When vesicle-coated microspheres were treated with trypsin and chymotrypsin or heated, this resulted in a significant loss of attachment, suggesting a possible involvement of proteinaceous molecules in the process. The present study confirms that vesicles of P. gingivalis are capable of attachment to various molecules and indicate their potential role in colonization.     

Outer dense fibres of human spermatozoa: partial characterization and possible physiological functions

The outer dense fibres are accessory fibres in the spermatozoon. They represent up to 30% of the protein portion in human spermatozoa and are involved in sperm progressive motility. If outer dense fibres are missing or developed poorly, spermatozoa are only locally motile. For isolation of the outer dense fibres, human spermatozoa were sonicated at 25 kHz and the flagella were separated by density gradient centrifugation in Percoll. Thereafter, membranes and fibrous sheath were dissolved under reducing conditions in the cationic detergent cetyltrimethylammonium bromide for 30, 60 and 90 min, respectively. The isolation steps were monitored by phase contrast microscopy and electron microscopy. After SDS-polyacrylamide gel electrophoresis and silver staining of isolated outer dense fibres, two protein bands at 55 and 67 kDa could be detected. By means of rhodamine B staining, no phosphorus could be detected in the outer dense fibre proteins.     

Ventrally emigrating neural tube cells migrate into the developing vestibulocochlear nerve and otic vesicle

Virtually all cell types in the inner ear develop from the cells of the otic vesicle. The otic vesicle is formed by the invagination of non-neural ectodermal cells known as the otic placode. We investigated whether a recently described cell population, originating from the ventral part of the hindbrain neural tube known as the ventrally emigrating neural tube (VENT) cells, also contributes cells to the otic vesicle. The ventral hindbrain neural tube cells were labeled with the fluorescent vital dye DiI or replication-deficient retroviruses containing the LacZ gene in chick embryos on embryonic day 2, after the emigration of neural crest from this region. One day later, the labeled cells were detected only in the hindbrain neural tube. Shortly thereafter, the labeled cells began to appear in the eighth (vestibulocochlear) cranial nerve and otic vesicle. From embryonic day 3.5-5, the labeled cells were detected in the major derivatives of the otic vesicle, i.e. the endolymphatic duct, semicircular canals, utricle, saccule, cochlea, and vestibulocochlear ganglion. That the emigrated cells originated from the ventral part of the hindbrain neural tube was confirmed by focal application of DiI impregnated filter paper and with quail chimeras. It is concluded that, in addition to the otic placode cells, the otic vesicle also contains the ventrally emigrating neural tube cells, and that both cell populations contribute to the structures and cell types in the inner ear. It is well known that inductive signals from the hindbrain are required for the morphogenesis of the inner ear. The migration of the hindbrain neural tube cells into the otic vesicle raises the possibility that the inductive effect of the hindbrain might be mediated, at least in part, by the ventrally emigrating neural tube cells and that, therefore, a mechanism exists that involves cells rather than diffusible molecules only.     

Scintigraphic visualization of intrathecal liposome biodistribution

Background: Liposomes containing local anaesthetics have been administered intrathecally and in the epidural space. Poor attention has been given to the pharmacokinetics of liposomes as drug carriers. Therefore, we observed the biodistribution of liposomes after intrathecal injection in rats by scintigraphic imaging during 24 h.
Methods: We administered ⁹⁹Tc-labeled multilamellar (MLV) and small unilamellar vesicles (SUV) of defined size and volume dispersities into the cerebrospinal fluid at the lumbar level. Those vesicles were free of contamination by radiolabeled colloids as visualized by light and electron microscopy and of neurotoxic products from phosphatidylcholine hydrolysis and peroxidation, both during the preparation process and after 24 h incubation in cerebrospinal fluid at 37°C in vitro.
Results: SUV immediately diffused from the lumbar site of injection to the head and were cleared between 1 and 24 h after injection. MLV were cleared more slowly from the spinal space and appeared in the head region 1 h after injection where they accumulated up to 24 h. These differences were explained in terms of vesicle sizes and volumes. SUV with 0.05 μm diameters were rapidly absorbed into the blood through the arachnoid granulations. In contrast, particles larger than the upper size limit of the arachnoid granulations permeability (±8 μm) could accumulate in the head with a slow elimination rate.
Conclusion: This difference in clearance from the intrathecal space outlines the importance of defining the size of the liposomes, the distribution of a tracer or a drug inside the liposomal preparation, the chemical stability and the absence of toxic degradation products of liposome formulations before clinical use.     

Direct effect of cadmium on citrate uptake by isolated rat renal brush border membrane vesicles

High incidence of multiple kidney stone formation has been observed among workers exposed to cadmium (Cd). Citrate is known to be a protective factor against renal stone formation. To study the direct effect of cadmium on citrate uptake by the renal brush border membrane, we exposed isolated rat renal brush border membrane vesicles (BBMV) to cadmium and determined their citrate uptake characteristics. BBMV were prepared by the divalent cation precipitation method. Citrate uptake was measured by the Millipore rapid membrane filtration technique. Preincubation of BBMV with 2 and 10 mM CdCl₂ for 1 min significantly inhibited citrate uptake compared with that of BBMV without Cd. Analysis of the time course of citrate uptake during 30-min preincubation of BBMV with 0.5 mM Cd also revealed significant reduction of the uptake compared with that of the control BBMV without preincubation. These findings indicate that preincubation of BBMV with cadmium results in time-dependent and concentration-dependent inhibition of citrate uptake.     

Distribution and structure of identified tonic and phasic synapses between L-neurones in the locust ocellar tract.

The ultrastructures and distributions of the discrete anatomical synapses which constitute two distinct types of output connections made by individual ocellar L-neurons, L1-3, are described. Outputs to neurones L4-5 are excitatory and transmit tonically, whereas reciprocal connections among the three L1-3 neurones are inhibitory and incapable of transmission for longer than a few milliseconds. The tonically transmitting synapses are located in the lateral ocellar tract and are made between the axons of L1-3, which do not receive inputs, and short branches of L4-5, which make no outputs. Each excitatory connection is composed of a few hundred discrete anatomical synapses, each characterised by a bar-shaped presynaptic density which is 0.15-1.5 microns in length and associated with a large number of round synaptic vesicles. Two postsynaptic profiles are apposed to each presynaptic density. Associated with tonic synapses are abundant invaginations of the presynaptic membrane. Synapses of the reciprocal, inhibitory, phasic connections occur in the protocerebral arbors of L1-3, among numerous output synapses of these neurones. Each phasic connection is composed of a few tens of discrete anatomical synapses. Each bar-shaped presynaptic density is associated with two postsynaptic profiles, and is 0.1-1.0 microns long. Compared with the tonic, excitatory connection, there are fewer vesicles and fewer invaginations of the presynaptic membrane associated with each synapse.