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PubMed1956

Present status of serological tests for syphilis.

The authors first discuss the advantages and disadvantages of the various serological tests now in common use, or coming into use, for the detection and management of syphilis and also compare the different antigens used in those tests. They lay stress on the difficulties caused by the "unit" system of recording results, whereby identical findings with two or more tests may be given different numerical values for each test, and suggest that results should instead be given in dilution reactivity end-points (dils).False positive reactions to serological tests and discrepancies in the results of different tests are then considered; it is pointed out that these discrepancies may be due to causes in the patient himself, in transit, or in the testing laboratory.Finally, the authors consider that in view of the growing number of serological tests for syphilis, and of modifications to those tests, there is now a need for selecting, in different areas of the world, a certain number of procedures which can be standardized for routine testing. Regional serological evaluation studies can be used to this end. A brief outline is given of the United States Public Health Service programme to assist State laboratories to maintain a high level of efficiency in serological testing and thus to exert an influence on other laboratories within each State.

Humans↗

PubMed1992

Trigeminal ganglion cell processes are spatially ordered prior to the differentiation of the vibrissa pad.

The rodent trigeminal system is characterized by the punctate organization of its afferents and neurons that replicate the distribution of mystacial vibrissae and sinus hairs on the snout. We have examined the development of topographic equivalence between the sensory periphery on the snout and the brainstem trigeminal nuclei in rats. Lipophilic tracers Dil (1,1'-dioctodecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate) and DiA [4-(4-dihexadecylaminostyryl)-N-methylpyridinium iodide] were used to label trigeminal ganglion cells and their processes differentially from discrete regions of the presumptive vibrissa field in fixed embryos. Our results show that trigeminal ganglion cell processes are spatially ordered as they reach their peripheral and central targets on embryonic day 12 (E12). Peripheral processes of dorsomedially situated ganglion cells course dorsally toward the presumptive vibrissa field, and those of ventrolaterally situated ganglion cells project ventrally. On E13, the central processes of dorsomedially situated ganglion cells enter the brainstem medially whereas those of ventrolaterally situated ganglion cells enter laterally. This spatial order of trigeminal ganglion cell processes precedes the emergence of vibrissa rows in the periphery and the differentiation of brainstem trigeminal nuclei. Thus, the subsequent transfer of the vibrissa-related pattern to the brainstem trigeminal nuclei occurs along a preexisting, spatially aligned bridge formed by the trigeminal ganglion cells.

Animals↗

PubMed2003

[Transplantation of cord blood endothelial progenitor cells ameliorates limb ischemia].

OBJECTIVE: To investigate the feasibility of transplanting cord blood CD133+ cells derived endothelial progenitor cells (EPC) in therapeutic vasculogenesis. METHODS: CD133+ cells from the cord blood of 52 neonates were cultured in fibronectin-coated flask in M199 medium supplemented with 10% fetal bovine serum, 50 ng/ml vascular endothelial growth factor (VEGF), 20 ng/ml interleukin-3 (IL-3) and 50 ng/ml stem cell factor (SCF). The cell markers of spindle-shaped adherent cells were determined with flow cytometry. The left femoral artery, great saphenous artery, iliac circumflex artery, and vein, and muscular branch of 22 Balb/c nude mice were cut to cause limb ischemia. One day after the unilateral ischemic limb surgery half million adherent cells were transplanted into 12 nude mice via tail vein (EPC group) and M199 was injected into the tail veins of 10 nude mice (M199 group). Fluorescence Dil, laser Doppler perfusion imaging (LDPI) and immunohistochemistry were Laser Doppler perfusion imaging (LDPI) was used to trace the transplanted cells and monitor the blood perfusion and capillary density of ischemic limbs. The ratio between the blood perfusion of the operated limb and of the non-operated opposite limb was recorded. Two to four mice in each group were killed 4, 7, 14, and 21 days after the operation and the gastrocnemius muscles of bilateral hind limbs were taken to count the number of capillaries. The VEGF mRNA levels of the ischemic and nonischemic limbs were examined with semi-quantitative RT-PCR. Seven days after the operation, fluorescein isothiocyanate (FITC)-binded ulex europaeus agglutinin-1 (UEA-1) was injected via tail vein to 3 EPC group mice. Thirty minutes later, the mice were killed. The heart, lung, liver, spleen and limb muscles were taken and examined with fluorescence microscopy. EPC were added into the upper chamber of Coster Transwell and chemotactic fluids of M199 with or without VEGE were added into the lower chamber. Four hours later the number of EPC in the lower chamber was counted so as to examine the chemotactic effect of VEGE. RESULTS: Numerous cell clusters, spindle-shaped adherent cells and cord-like structures, developed from the culture of cord blood CD133+ cells. These adherent cells expressed vascular endothelial growth factor receptor 2 (VEGFR-2), VE-cadherin, CD31, von Willebrand factor (vWF) and combined with ulex europaeus agglutinin-1 (UEA-1). Transplanted EPC survived and were incorporated into the capillary networks in the ischemic limbs of nude mice. The ratio between the blood perfusion of the ischemic limb and non-ischemic limbs was 19.1% +/- 3.1%. Two weeks after the transplantation, the ratio between the blood perfusion of the ischemic limb and non-ischemic limbs of the EPC group was 77.3% +/- 5.6%, significantly higher than that of the M199 group (40.6% +/- 3.4%, P<0.001). CD31 histochemical staining showed that the density of capillaries in the gastrocnemius muscles of ischemic hind limb was significantly higher 7, 14, and 21 days after operation in the EPC group than in the M199 group (P<0.05) RT-PCR showed obvious VEGF bands in the ischemic hind limb muscles, but not in the non-ischemic muscles. The number of EPC immigrating into the lower chamber of the Coster Transwell was 817 +/- 32.5, significantly higher than that of the control group (473.5 +/- 61.5, P<0.05). CONCLUSION: Cord blood CD133+ cells derived EPC is a robust cell source for therapeutic neovascularization. Upregulated expression of VEGF may account for the homing of transplanted EPC to ischemic tissue.

AC133 Antigen↗

PubMed1992

Dynamics of terminal arbor formation and target approach of retinotectal axons in living zebrafish embryos: a time-lapse study of single axons.

In a variety of species, developing retinal axons branch initially more widely in their visual target centers and only gradually restrict their terminal arbors to smaller and defined territories. Retinotectal axons in fish, however, appeared to grow in a directed manner and to arborize only at their retinotopic target sites. To visualize the dynamics of retinal axon growth and arbor formation in fish, time-lapse recordings were made of individual retinal ganglion cell axons in the tectum in live zebrafish embryos. Axons were labeled with the fluorescent carbocyanine dyes Dil or DiO inserted as crystals into defined regions of the retina, viewed with 40x and 100x objectives with an SIT camera, and recorded, with exposure times of 200 msec at 30 or 60 sec intervals, over time periods of up to 13 hr. (1) Growth cones advanced rapidly, but the advance was punctuated by periods of rest. During the rest periods, the growth cones broadened and developed filopodia, but during extension they were more streamlined. (2) Growth cones traveled unerringly into the direction of their retinotopic targets without branching en route. At their target and only there, the axons began to form terminal arborizations, a process that involved the emission and retraction of numerous short side branches. The area that was permanently occupied or touched by transient branches of the terminal arbor--"the exploration field"--was small and almost circular and covered not more than 5.3% of the entire tectal surface area, but represented up to six times the size of the arbor at any one time. These findings are consistent with the idea that retinal axons are guided to their retinotopic target sites by sets of positional markers, with a graded distribution over the axes of the tectum.

Animals↗

PubMed2005

Neuropathology of HIV/AIDS with an overview of the Indian scene.

Neurological manifestations of HIV infection and AIDS are being recognized with a frequency that parallels the increasing number of AIDS cases. Next to sub-Saharan Africa, India has the second largest burden of HIV related pathology, essentially caused by HIV-1 clade C in both the geographic locales, in contrast to USA and Europe. But the true prevalence of HIV related neuroinfections and pathology is not available due to inadequate medical facilities, social stigma and ignorance that lead to underdiagnosis. Neurotuberculosis, followed by cryptococcosis and toxoplasmosis in various combinations are the major neuropathologies reflecting the endemicity and manifesting clinically by reactivation of latent infection. Discordance in the clinical prevalence of various infections, when compared to pathological studies highlight similarities in clinical, radiological modalities of diagnosis and inherent problems in establishing definitive diagnosis. Viral infections appear to be relatively rare. Inspite of heavy burden of HIV/AIDS, HIV associated neoplasia is infrequent, including primary CNS lymphomas. HIV encephalitis and HIV associated dementia are considered infrequent, though systematic studies have just been initiated in various centres. Peripheral neuropathy characteristically manifests with vasculitic neuropathy while diffuse infiltrative lymphocytosis syndrome (DILS) involving nerves has not been reported from India. Spinal cord pathology including vacuolar myelopathy is rare, even in asymptomatic cases. Till now the AIDS cases in India were drug naive but a new cohort of cases following initiation of HAART therapy as a national policy is soon emerging, altering the biology and evolution of HIV/AIDS in India. Lacunae in the epidemiology, diagnosis and study of biology of HIV/AIDS are outlined for future research.

Antiretroviral Therapy, Highly Active↗

PubMedDate not supplied

Evaluation of mesenchymal stem cells following implantation in alveolar sockets: a canine safety study.

PURPOSE: The overall goal of this project was to evaluate culture-expanded bone-marrow-derived mesenchymal stem cells (MSCs) for alveolar bone repair in terms of safety and potential efficacy. MATERIALS AND METHODS: MSCs isolated from bone marrow aspirations were culture-expanded and cryopreserved. Thawed cells were incubated with 3.2 x 5-mm hydroxyapatite/tricalcium phosphate (HA/TCP) cylinders in a closed system containing 5 x 10(7) cells/mL. Cells alone, cell-free constructs, or cell-loaded constructs were rinsed in saline and implanted in extraction sockets in the mandibular second and fourth premolar sites of 14 beagle dogs. Acute reactions were evaluated histologically after 7 or 21 days, and bone formation was examined after 49 days. RESULTS: Neither implanted MSC-related inflammation nor ectopic osteogenesis was observed. At 7 and 21 days, dil-labeled canine MSCs were found in more than 80% of the implant sites. Few canine MSCs were found in neighboring tissue. Mild inflammation present at 7 days diminished by 21 days. After 49 days, measured bone formation was 34%, 25%, and 35% for cell-loaded, cell-free, and untreated sockets, respectively (P < .05). At 21 days, bone formation was evident in all sites. Wound dehiscence was a complication associated with cell exclusionary membranes and resulted in local inflammation. DISCUSSION: The extraction model indicates the safety of MSCs implanted adherent to HA/TCP. Local bone repair occurred in the absence of nonspecific differentiation or migration with distant osteogenesis. CONCLUSIONS: An alveolar socket model may be an appropriate model for initial clinical investigation of MSC-mediated bone repair.

Animals↗

PubMed2003

High-throughput screening for isolation of enhanced green fluorescent protein expressing transformants of filamentous fungus using an image analyzer.

High-throughput screening of enhanced green fluorescent protein (EGFP) gene-trap transformants of filamentous fungus was achieved for the first time using an image analyzer to measure their fluorescent intensity. For quantitative analysis of EGFP fluorescent intensity per unit cell mass, we developed a method for measurement of cell mass using the fluorescent dye SP-Dil. This method offers an effective and convenient tool for screening transformants expressing fluorescent protein as a reporter, and for quantitative analysis of fungal cell mass at jig levels.

Journal Article↗

PubMed2005

[Therapeutic neovascularization with autologous bone marrow CD34+ cells transplantation in hindlimb ischemia].

OBJECTIVE: To explore whether transplantation of autologous bone marrow stem cells might augment angiogenesis and collateral vessel formation in a canine model of hindlimb ischemia. METHODS: CD34(+) stem cells were centrifugation through Ficoll and an immune magnetic cell sorting system from bone marrow (20 ml) of canine (n = 5) and induced into endothelial cells with VEGF in vitro, and expression of von Willebrand factor. Bilateral hindlimb ischemia was surgically induced in canines and Dil fluorescence labeled autologous stem cells were transplanted into the ischemic tissues. RESULTS: Four weeks after transplantation, fluorescence microscopy revealed that transplanted cells were incorporated into the capillary network among preserved skeletal myocytes. The stem cells transplanted group had more angiographically detectable collateral vessels, a higher capillary density (12.0 +/- 2.8 vs. 5.0 +/- 1.6 per field; t = 4.17 P < 0.05) and a higher ABI (0.58 +/- 0.14 vs. 0.32 +/- 0.11; t = 2.95, P < 0.05). CONCLUSIONS: Direct local transplantation of autologous bone marrow CD34(+) stem cells seems to be a useful strategy for therapeutic neovascularization in ischemic tissues in adults, consistent with "therapeutic vasculogenesis."

Animals↗

PubMed2006

Six novel mutations of the LDL receptor gene in FH kindred of Sicilian and Paraguayan descent.

Familial hypercholesterolemia (FH) is an autosomal dominant inherited disease caused by mutations in the gene coding for the low density lipoprotein receptor (LDL-R). It is characterized by a high concentration of low density lipoprotein (LDL), which frequently gives rise to premature coronary artery disease. We studied the probands of five FH Sicilian families with 'definite' FH and one proband of Paraguayan descent with homozygous FH who has been treated with an effective living-donor liver transplantation. In order to seek the molecular defect in these six families, we used direct sequencing to define the molecular defects of the LDL-R gene responsible for the disease. We described three novel missense mutations (C100Y, C183Y and G440C), two frameshift mutations (g.1162delC in exon 8 and g.2051delC in exon 14) and one mutation (g.2390-1Gright curved arrow A) at splicing acceptor consensus sequences located in intron 16 of the LDL-R gene; the analysis of cDNA of this splicing mutation showed the activation of a cryptic splice site in intron 16 and the binding studies showed a reduction in internalisation of LDL-DIL in the proband's cultured fibroblasts. Moreover, a g.2051delC in exon 14 was identified in the proband of Paraguayan ancestry with clinical features of homozygous FH. The mutation identified in the South American patient represents the first description of a variant in South American patients other than Brazilian FH patients. The 5 mutations identified in the Sicilian patients confirm the heterogeneity of LDL-R gene mutations in Sicily.

Adult↗

PubMed2006

[Establishment of animal model of chronic optic nerve injury and pathological changes thereof: experiment with cats].

OBJECTIVE: To establish an animal model of chronic optic nerve injury which is suitable for experimental research. METHODS: Dil, a tracer, was injected through the bone windows into the brain of 48 cats so as to mark the retinal ganglion cells (RGCs). Two weeks later the 48 cats were randomly divided into 6 equal groups. The normal group did not receive any other treatment. Other 8 cats underwent sham operation. Imitating the clinical pterional approach, a balloon was implanted into the place under the optic nerve and chiasm in the other 32 cats, then the volume of the balloons were increased by injecting contrast agent at different times to cause the optic nerve and chiasm compressed chronically for 1, 2, 4, or 6 weeks. Flash-visual evoked potential (F-VEP) was measured before operation and at the corresponding observation times in different groups. By the end of the experiment the cats were killed with the specimens of retina and optic nerve taken out to undergo light microscopy and electron microscopy to observe the pathological changes. Eight eyes were taken out from each group to calculate the number of RCGs 1, 2, 4, and 8 weeks after operation respectively. RESULTS: Microscopy showed retina showed profound morphological changes 8 weeks after compression; Demyelination of optic nerve began to occur 2 weeks after compression and progressed later. Axonal degeneration was found 4 week after compression and became more significant 8 weeks later. Under electron microscopy, pathological changes of retina was found 4 weeks and more prominent 8 weeks after compression; Slight demyelination and disorganized of cytoskeleton in the optic nerve were shown 2 weeks after compression, and became more profound later; Myelin regeneration was found 8 weeks after compression. The number of RGCs was reduced significantly by 37% (293/465) since 8 weeks after compression. F-VEP recording showed an extension of latency and depression of amplitude 4 weeks after compression, and the changes were more significant 8 weeks later. CONCLUSION: An animal model of chronic optic nerve injury by compression has been established which is stable and well repeatable. The pathological changes of compressed optic nerve are aggravated gradually as the compression lasts and the volume increases. Degeneration of RGCs occurs secondarily and obviously later than the axonal degeneration.

Animals↗

PubMed1991

Innervation and regulation of the pancreas by neurons in the gut.

Experiments were done in order to test the hypothesis that enteric neurons project to the pancreas and can modify pancreatic endocrine and exocrine activity. Injections of the retrograde tracer Fluoro-Gold (FG) into the rat pancreas labeled neurons in the myenteric plexus of the antrum of the stomach and in the first 6 cm of the duodenum. A subset of myenteric neurons were found in both the antrum and duodenum that were doubly labeled by retrograde transport of FG and anti-serotonin (5-HT) sera; therefore, some of the enteric neurons that innervate the pancreas are serotonergic. Within the pancreas, 5-HT-immunoreactivity was not found in any neuronal cell bodies; however, 5-HT-immunoreactive axons were observed. Varicose 5-HT-immunoreactive terminal axons were most commonly found in pancreatic ganglia. Anterograde tracers were microinjected into individual myenteric ganglia in order to determine the pancreatic targets of the enteric innervation. Following the microinjection of the B subunit of cholera toxin (B-CT) or 1,1", dioctadecyl-3,3,3',3'-tetramethylcarbocyanine (Dil) into myenteric ganglia in the duodenum, labeled fibers were found in the pancreatic parenchyma. B-CT-immunoreactive terminals were most commonly observed in pancreatic ganglia, suggesting that pancreatic ganglia are the major targets in the pancreas of the enteric innervation. Experiments were also performed physiologically to determine whether enteric stimuli can influence pancreatic exocrine or endocrine activity via a neural pathway. For this purpose enteric neurons were stimulated in vitro by luminal application of veratridine (Ver), and the metabolic activity of neurons, islet, and acinar cells was determined in attached segments of pancreas by measuring their cytochrome oxidase (CO) activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2002

[The anatomists who started anthropology in Turkey and their contributions].

The Turkish Institute of Antropology was estabilished in 1925 as a unit of the Medical School of Istanbul University (Darülfünun), named the Antropology Research Center (Antropoloji Tetkikat Merkezi). It was a part of the medical faculty until 1932. After the university reform it was connected to the School of Science and in late 1935 it was transfered to the School of Languages History and Geography (Dil Tarih Coğrafya Fakültesi) in Ankara. The center started to publish "The Journal of Turkish Anthropology" with Dr. Nuretttin Ali Berkols researches in 1925. It was published in two languages, Turkish and French. The faculty members of the institute, Dr. Mouchet, Dr. Süreyya Ali and Dr. Ismail Hakki formed the editorial board of the journal. We see that from the first issue of the journal in 1925 until the special issue prepared for the XVIII. Anthropology and Prehistorical Archealogy Congress in 1939, Dr. Nurettin Ali Berkol and Dr. Mouchet were members of the administrative committee of the journal. In this article; we studied the contributions of the anatomists to the development of anthropology in Turkey.

Anatomy↗

PubMed1992

Pathfinding and target selection by developing geniculocortical axons.

During development of the mammalian cerebral cortex, thalamic axons must grow into the telencephalon and select appropriate cortical targets. In order to begin to understand the cellular interactions that are important in cortical target selection by thalamic axons, we have examined the morphology of axons from the lateral geniculate nucleus (LGN) as they navigate their way to the primary visual cortex. The morphology of geniculocortical axons was revealed by placing the lipophilic tracer Dil into the LGN of paraformaldehyde-fixed brains from fetal and neonatal cats between embryonic day 26 (E26; gestation is 65 d) and postnatal day 7 (P7). This morphological approach has led to three major observations. (1) As LGN axons grow within the intermediate zone of the telencephalon toward future visual cortex (E30-40), many give off distinct interstitial axon collaterals that penetrate the subplate of nonvisual cortical areas. These collaterals are transient and are not seen postnatally. (2) There is a prolonged period during which LGN axons are restricted to the visual subplate prior to their ingrowth into the cortical plate; the first LGN axons arrive within visual subplate by E36 but are not detected in layer 6 of visual cortex until about E50. (3) Within the visual subplate, LGN axons extend widespread terminal branches. This represents a marked change in their morphology from the simple growth cones present earlier as LGN axons navigate en route to visual cortex. The presence of interstitial collaterals suggests that there may be ongoing interactions between LGN axons and subplate neurons along the entire intracortical route traversed by the axons. From the extensive branching of LGN axons within the visual subplate during the waiting period, it appears that they are not simply "waiting." Rather, LGN axons may participate in dynamic cellular interactions within the subplate long before they contact their ultimate target neurons in layer 4. These observations confirm the existence of a prolonged waiting period in the development of thalamocortical connections and provide important morphological evidence in support of the previous suggestion that interactions between thalamic axons and subplate neurons are necessary for cortical target selection.

Aging↗

PubMed1991

Characterization of Cobblestone mitral valve interstitial cells.

Mitral valve interstitial cells (MVICs) are important in the structure and function of the valve. In a cell culture system that used explants to harvest MVICs, we found that after several passages, some of the cultures at confluence formed a monolayer of cobblestone-shaped cells (CB type). The rest of the cultures were, however, different, consisting of elongated cells (EL type) that formed overlapping orthogonal patterns. When compared with the MVICs-EL, cells from cultures of MVICs-CB were less adherent to a plastic substratum initially than were MVICs-EL and were more sensitive to trypsinization following culture for 3 to 7 days. Ultrastructurally, the cultures of MVICs-CB showed prominent Golgi's complexes and endoplasmic reticulum and fewer microfilaments when compared with those of MVICs-EL. Most strikingly, the CB cells contained much less alpha-smooth-muscle cell actin compared with that of EL cells. The MVICs-CB were not endothelial cells as they did not show the characteristic dense peripheral band that was present in endothelial cells in a confluent monolayer and showed only trace amounts of fluorescence when incubated with 1,1-dioctadecyl 1-3,3,3,3 tetramethyl-indocarbocyanine-percholate (Dil-)--acetylated low-density lipoprotein compared with large amounts of fluorescence with endothelial cells. Cells that were morphologically similar to MVICs-CB were present in the in vivo valve as well and also formed small islands of cells even in the primary cultures that grew out of the explant. The findings supported the hypothesis that MVICs-CB represent a distinct phenotype of the MVICs that is different from that of the MVICs-EL and is not that of either endothelial or medial smooth-muscle cells.

Actin Cytoskeleton↗

PubMed1991

Transmission of intestinal schistosomiasis in Bahir Dar, northwest Ethiopia.

Parasitological, malacological and transmission studies were made for a period of one year in the town of Bahir Dar, northwest Ethiopia. The overall prevalence of schistosomiasis mansoni in residents of Kebeles 8, 9 and 10 was 12%. The prevalence in Sertse Dengel school children was 45% and that in Dil Chibo school children was 32%. The peak prevalence in both sexes in school and non-school populations occurred in the age group 10-14 years. Intensity of infection showed a similar pattern of age variation as prevalence. Biomphalaria pfeifferi snail density peaked towards the end of the rainy season (September) in Lake Tana and around the middle of the dry season (January) on the shore of the River Abay. In September, infected snails were recovered from all collection sites. Of mice immersed in four water contact sites in September, schistosome infections developed in those immersed in three sites. Parasitological findings suggested that schistosomiasis infection rates depended on age and sex of individuals and geographical location of the place from the potentially infective water bodies. Snail population density and associated schistosomal infection in a human population depended on rainfall and associated ecological changes such as fluctuation in water level and vegetation density. As malacological findings and sentinel mouse immersion results indicated, it appeared that the main transmission season in Lake Tana region is towards the end of the rainy season although low level intermittent transmission may take place throughout the year.

Adolescent↗

PubMed1991

Stages of growth of hamster retinofugal axons: implications for developing axonal pathways with multiple targets.

Neurons in many regions of the CNS (e.g., cortical areas, thalamic nuclei) are heterogeneous with regard to their afferent and efferent connections. Using the hamster retinofugal system as a model, we investigated the mechanisms by which such connectional heterogeneity arises during ontogeny. Retinal ganglion cell axons were labeled with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (Dil) in paraformaldehyde-fixed tissue. The fluorescent label was photoconverted to a diaminobenzidine reaction product. The morphology of the axons, including their trajectories, branching patterns, and growth cones, was studied at the level of the dorsal lateral geniculate nucleus (LGd) from embryonic day 14 to adulthood. In adult hamsters, axons of retinal ganglion cells (RGCs) are spatially segregated at the level of the lateral geniculate nucleus into a superficial optic tract, situated just beneath the pia, and an internal optic tract consisting of fascicles running parallel to the pia within the geniculate. All retinofugal axons project to the midbrain, but only superficial optic tract axons emit collaterals to the LGd. During development, axons in both divisions of the optic tract emit collaterals to the LGd, but by postnatal day 15, collaterals of internal optic tract axons are virtually entirely eliminated, whereas those of superficial optic tract axons have elaborated terminal arbors. Thus, the heterogeneity among different classes of RGCs with respect to their efferent connections emerges by the selective stabilization, by each class, of a unique subset of connections from an initially widespread set shared by all classes. Thalamic collaterals of RGC axons emerge along established axon trunks, not by bifurcation of the growing tip. This occurs after the axons have grown past the thalamus and, presumably, entered their targets in the midbrain. Growth cones at the tips of elongating axon trunks are larger in size and have a more "complex" morphology compared to the growth cones on collaterals. Axons of RGCs develop in 3 morphologically distinct growth states. First, they elongate to their most distant targets in the midbrain. Then, they simultaneously emit unbranched or poorly branched collaterals to multiple targets. Finally, they elaborate terminal arbors in their definitive targets and eliminate their other collaterals. This developmental strategy may be paradigmatic for the formation of long CNS pathways with multiple targets. Furthermore, these data document, at the single-axon level, the steps in the elaboration and withdrawal of transient neuronal projections.

Animals↗

PubMed1991

Neointimal formation in the porcine aortic organ culture. I. Cellular dynamics over 1 month.

Since intimal smooth muscle cells (SMC) are an important feature of atherosclerotic fibrofatty plaques, we tested the hypothesis that endothelial cells (EC) regulate SMC proliferation in the process of neointimal formation. Using a porcine thoracic aortic organ culture (OC) system, we previously showed in a preliminary study that short-term porcine aortic explants incubated in 5% fetal bovine serum for 7 days promote neointimal formation only in the presence of endothelium or in conditioned media collected from proliferating OC with endothelium present. We now report that these organ cultures can be maintained in culture for up to 4 weeks. The surface cells stained positively for dil-acetylated-low-density lipoprotein throughout the 4-week period indicating the continued presence of EC while the neointimal cells stained positively for the smooth muscle actin-specific monoclonal antibodies alpha-SM1 and HHF-35 indicating their smooth muscle nature. The number of EC did not change during the 4-week incubation period, however, EC turnover peaked at 5 days and remained elevated but constant throughout. The number of intimal SMC doubled between day 0 (18.4 +/- 0.2 cells/field) and day 7 (41.5 +/- 0.9) and between day 7 and day 14 (75.8 +/- 10.1). The intimal SMC number then stabilized thereafter (day 21: 79.5 +/- 7.8, day 28: 73.8 +/- 12.1). Cell proliferation played a large part since autoradiography studies using nondenuded OC showed that intimal SMC thymidine index on day 0 was 1.4% +/- 0.4, peaked at the end of day 5 (25.7% +/- 4.1) and gradually decreased thereafter. The peak in the intimal SMC thymidine index occurred during a period of high EC turnover (maximum EC thymidine index on day 5: 21.8% +/- 2.1), and the stabilization of intimal SMC number observed beyond 2 weeks of incubation occurred when EC replication was reduced (day 14: 6.7% +/- 0.21). Incubation of organ cultures denuded of their endothelium in 5% fetal bovine serum showed a marked decrease in neointimal formation. However, denuded OC when incubated in conditioned medium collected from 4-day-old nondenuded OC (4DCM) enhanced neointimal formation of denuded OC. In contrast, the neointima of denuded OC incubated in 24-day-old nondenuded OC conditioned medium was similar to that of controls. The thymidine index of intimal SMC of denuded OC treated with 4DCM was markedly higher than that found with the control treatment at all time points.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1990

Cell interactions regulate dendritic morphology and responses to neurotransmitters in embryonic chick sympathetic preganglionic neurons in vitro.

The influence of non-neuronal cells and interneurons on the morphological development of chick sympathetic preganglionic neurons (SPNs) and on the responsiveness of these neurons to the neurotransmitters GABA, glycine, and glutamate was studied. SPNs were retrogradely labeled with the fluorescent dyes dil and diO, then separated from spinal-cord non-neuronal cells and interneurons by fluorescence-activated cell sorting. SPNs were grown in culture, either alone or in coculture with non-neuronal cells alone, with interneurons alone, or with both of these cell types (control cultures). The responsiveness of SPNs to neurotransmitters was assessed by whole-cell recording, while cell morphology was assessed after intracellular staining with 6-carboxyfluorescein. Cell size and morphology were affected by non-neuronal cells. In the absence of non-neuronal cells, SPNs had smaller cell bodies and fewer major processes, whether or not interneurons were present. In contrast, responses to the 3 neurotransmitters were affected by both non-neuronal cells and interneurons, but in ways that differed slightly for each transmitter. In the absence of both non-neuronal cells and interneurons, responses to all 3 transmitters were much smaller than in control cultures, with responses to glutamate most profoundly affected. The addition of either non-neuronal cells or interneurons slightly increased the amplitude of SPN responses to glutamate, but the level of responsiveness with either cell type alone was much lower than for SPNs grown in the presence of both cell types. The addition of interneurons also slightly increased the responsiveness of SPNs to GABA, but non-neuronal cells alone had no significant effect on the responses of SPNs to GABA. Finally, the glycine responsiveness of SPNs was raised to control levels when either non-neuronal cells or interneurons were added. These experiments demonstrate that, though interneurons can have a significant inductive effect on the responses of SPNs to neurotransmitters, not all of the changes in neurotransmitter responsiveness can be related to the formation of functional synapses.

Animals↗