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1.
Clin Pharmacol Ther ; 99(4): 370-80, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26765077

ABSTRACT

γ-Secretase mediates amyloid production in Alzheimer's disease (AD) and oncogenic activity of Notch. γ-Secretase inhibitors (GSIs) are thus of interest for AD and oncology. A peripheral biomarker of Notch activity would aid determination of the therapeutic window and dosing regimen for GSIs, given toxicities associated with chronic Notch inhibition. This study examined the effects of GSI MK-0752 on blood and hair follicle transcriptomes in healthy volunteers. The effects of a structurally diverse GSI on rhesus blood and hair follicles were also compared. Significant dose-related effects of MK-0752 on transcription were observed in hair follicles, but not blood. The GSI biomarker identified in follicles exhibited 100% accuracy in a clinical test cohort, and was regulated in rhesus by a structurally diverse GSI. This study identified a translatable, accessible pharmacodynamic biomarker of GSI target engagement and provides proof of concept of hair follicle RNA as a translatable biomarker source.


Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Benzene Derivatives/pharmacology , Drug Monitoring , Hair Follicle/drug effects , Propionates/pharmacology , Protease Inhibitors/pharmacology , Receptors, Notch/antagonists & inhibitors , Sulfones/pharmacology , Transcription, Genetic/drug effects , Adolescent , Adult , Amyloid Precursor Protein Secretases/metabolism , Animals , Baltimore , Benzene Derivatives/administration & dosage , Benzene Derivatives/blood , Benzene Derivatives/pharmacokinetics , Biomarkers, Pharmacological/blood , Cross-Over Studies , Dose-Response Relationship, Drug , Double-Blind Method , Drug Monitoring/methods , Gene Expression Profiling/methods , Hair Follicle/metabolism , Healthy Volunteers , Humans , Macaca mulatta , Male , Models, Animal , Molecular Targeted Therapy , Oligonucleotide Array Sequence Analysis , Propionates/administration & dosage , Propionates/blood , Propionates/pharmacokinetics , Protease Inhibitors/administration & dosage , Protease Inhibitors/blood , Protease Inhibitors/pharmacokinetics , RNA, Messenger/biosynthesis , RNA, Messenger/blood , Receptors, Notch/metabolism , Sulfones/administration & dosage , Sulfones/blood , Sulfones/pharmacokinetics , Young Adult
3.
Eur Rev Med Pharmacol Sci ; 19(15): 2804-11, 2015 Aug.
Article in English | MEDLINE | ID: mdl-26241533

ABSTRACT

OBJECTIVE: The sacroiliac joint (SIJ) is one of the major sources of low back pain that can lead to severe morbidity. Possible SIJ pain requires a thorough evaluation and treatment option. The purpose of this study was to analyze the possible relationships between computed tomography (CT) grading of SIJ arthritis and the effectiveness of intraarticular steroid injection treatment under CT guidance. PATIENTS AND METHODS: A total of 61 patients with SIJ pain who were treated with CT guided intraarticular steroid injection were retrospectively reviewed. Visual analog scale (VAS) scores for pain control were recorded for short-term (day after injection, first week, third week) and long-term (sixth months and final control) follow-up times. SIJ arthritis was graded using CT images according to the New York criteria. Patients were assigned into low-grade (0, 1 and 2) and high-grade (3 and 4) groups. The relationship between arthritis grades and VAS scores in short and long-term follow-ups were statistically analyzed. RESULTS: Mean age and follow-up was 54.8 years (range: 41-68 years) and 27.8 months (range: 24-36 months), respectively. In 40 patients there was low-grade arthritis, while 21 patients were characterized on having high-grade sacroiliac arthritis detected during the radiological evaluation. There was no statistically significant difference between low and high-grade arthritis in regard to short-term VAS scores. On contrary, for long-term VAS scores, there was significant difference between low- and high-grade arthritis. CONCLUSIONS: Steroid injection treatment for SIJ pain is not effective on a long-term basis for patients with high-grade arthritis, and although they have had decreased VAS scores in the short-term, after 2 years of follow-up, their VAS scores significantly increased leading to symptomatic sacroiliac joint pain.


Subject(s)
Arthralgia/drug therapy , Arthritis/drug therapy , Injections, Intra-Articular/methods , Sacroiliac Joint/pathology , Tomography, X-Ray Computed/methods , Adult , Aged , Female , Follow-Up Studies , Humans , Male , Middle Aged , Retrospective Studies , Treatment Outcome
5.
Cardiovasc J Afr ; 22(6): e4-6, 2011 Dec 12.
Article in English | MEDLINE | ID: mdl-22159353

ABSTRACT

Behçet's disease is a multisystem inflammatory disorder that is classified among the vasculitides and can affect all types and sizes of blood vessels. Vascular manifestations of Behçet's disease are venous and arterial occlusion, and arterial aneurysms. As vasculitis of the vasa vasorum is the main pathological hallmark of Behçet's disease, it is generally seen as superficial thrombo-phlebitis or occlusion of the major veins; however arterial obstruction and aneurysms may also be seen to a lesser extent. Iliac artery stenosis is highly uncommon. Here, a case of common iliac stenosis in a 48-year-old patient with Behçet's disease is reported. As the risk of aneurysm during an operation was high in this patient, he was treated with vascular stent implantation. Due to stent occlusion two months after the operation, percutaneous transluminal angioplasty was performed with an 8-mm balloon. During the three-year follow up, no obstruction was observed.


Subject(s)
Arterial Occlusive Diseases/therapy , Behcet Syndrome/complications , Iliac Artery/diagnostic imaging , Angioplasty, Balloon , Arterial Occlusive Diseases/diagnostic imaging , Arterial Occlusive Diseases/etiology , Behcet Syndrome/pathology , Catheterization , Humans , Iliac Artery/pathology , Male , Middle Aged , Radiography , Stents
6.
Dentomaxillofac Radiol ; 39(6): 349-55, 2010 Sep.
Article in English | MEDLINE | ID: mdl-20729184

ABSTRACT

OBJECTIVES: the purpose of this study was to evaluate the accuracy of MRI combined with diffusion-weighted imaging (DWI) vs fine-needle aspiration cytology (FNAC) in diagnosing common parotid masses. METHODS: 25 consecutive patients (mean age 61 years) with parotid masses were included in this study. Informed consent and ethical approval was obtained. 22 patients underwent both MRI combined with DWI and FNAC. From DWI data, apparent diffusion coefficient maps were generated. The MRI study protocol consisted of T(1) weighted spin echo; T(2) weighted and T(2) weighted fat-suppressed turbo spin echo; DWI; and T(1) weighted fat-suppressed post-contrast images. MRI and FNAC diagnoses were compared with histopathology. Youden's index was used to compare the two methods. RESULTS: masses comprised eight Warthin tumours, eight adenomas (six pleomorphic adenomas, two basal cell adenomas), five carcinomas, two lipomas, one haemagioma and one benign lymphadenopathy. Technically, MRI was successful in 24 of the 25 patients (96%), FNAC was successful in 20 of the 23 patients (87.0%). The accuracy, sensitivity and specificity of MRI without DWI were 96%, 80% and 100%, respectively. Diagnostic accuracy did not increase by adding DWI to conventional MRI; however, DWI was helpful for diagnosing benign tumour histology. MRI combined with DWI was successful for determining accurate tumour typing in all benign masses except one lymphadenopathy. When FNAC had adequate material the accuracy, sensitivity and specificity were 95%, 75% and 100%, respectively. Youden's index was 0.80 for MRI and 0.75 for FNAC. CONCLUSIONS: MRI combined with DWI seems to have similar diagnostic potential as FNAC in differentiation of benign vs malignant parotid masses.


Subject(s)
Adenolymphoma/pathology , Adenoma/pathology , Biopsy, Fine-Needle , Carcinoma/pathology , Diffusion Magnetic Resonance Imaging , Parotid Neoplasms/pathology , Adult , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Sensitivity and Specificity , Statistics, Nonparametric
7.
Lung ; 188(5): 381-5, 2010 Oct.
Article in English | MEDLINE | ID: mdl-20607268

ABSTRACT

Lung transplantation (LTX) requires continual systemic immunosuppression, which can result in infections that may compromise recipient survival. A recent outbreak of Acinetobacter baumannii at our institution resulted in infections experienced in both LTX recipients and nontransplant patients. A retrospective review was conducted of patients who had A. baumannii recovered from blood, other normally sterile body fluids, and/or respiratory secretions and who had clinical follow-up extending to 1 year postinfection. A. baumannii was considered "multidrug-resistant" when its growth was not inhibited by minimum inhibitory concentrations of multiple antibiotics. Despite the resistance profile, patients were treated with a combination of antibiotics, which included tigecycline, colistimethate, and when susceptible, imipenem. Once infection was diagnosed, immunosuppression was reduced in all LTX recipients. Six LTX recipients became infected with A. baumannii and were contrasted to infections identified in 14 non-LTX, nonimmunosuppressed patients. A. baumannii was persistently recovered in 4 of 6 LTX recipients (66.7%) compared with only 1 of 14 (7.1%) non-LTX patients (χ(2) = 9.9, p = 0.005). LTX recipients received antibiotic therapy for an average of 76 ± 18.4 days compared with 16.0 ± 6.8 days for the non-LTX patients (p = 0.025, Mann-Whitney U test). All 4 of the 6 (66.7%) LTX recipients died as a consequence of their infection compared with 1 of 14 (7.1%) of the non-LTX patients (χ(2) = 9.9, p = 0.005). Despite receiving more antibiotic therapy, LTX recipients who were infected with multidrug-resistant A. baumannii were less likely to clear their infection and experienced greater mortality compared with non-LTX patients.


Subject(s)
Acinetobacter Infections/etiology , Acinetobacter Infections/mortality , Acinetobacter baumannii/isolation & purification , Lung Transplantation/adverse effects , Pneumonia, Bacterial/etiology , Pneumonia, Bacterial/mortality , Acinetobacter Infections/diagnostic imaging , Anti-Bacterial Agents/therapeutic use , Colistin/analogs & derivatives , Colistin/therapeutic use , Humans , Imipenem/therapeutic use , Immunosuppressive Agents/therapeutic use , Minocycline/analogs & derivatives , Minocycline/therapeutic use , Pneumonia, Bacterial/diagnostic imaging , Radiography , Retrospective Studies , Tigecycline
8.
Osteoarthritis Cartilage ; 18(5): 646-53, 2010 May.
Article in English | MEDLINE | ID: mdl-20175977

ABSTRACT

OBJECTIVE: To assess a walking model utilizing a set of standardized treadmill walks to measure acute analgesic response in osteoarthritis (OA) of the knee. DESIGN: Randomized, double-blind, placebo-controlled, multiple dose, three-period crossover study. Patients > or =45 years of age (N=22) with symptomatic knee OA were randomized to naproxen 500 mg bid, tramadol/acetaminophen 37.5 mg/325 mg in forced titration, or placebo in each of three periods. Patients performed multiple 20-minute treadmill walks on Day 1 and Day 3 at a consistent self-selected pace predetermined at screening. Pain intensity (PI) during the walks was assessed on an 11-point numerical rating scale at 0, 3, 6, 9, 12, 15, 18, and 20 min. The primary endpoint was the time-weighted average (TWA) change from baseline PI on Day 3 for the two self-paced walks for the active treatments vs placebo. Time to moderate pain (TTMP) was a key secondary endpoint. RESULTS: Compared with placebo, the TWA change from baseline PI on Day 3 was significantly better with tramadol/acetaminophen (P=0.043) but not with naproxen (P=0.089). TWA change from baseline on Day 1 was also significantly better with both tramadol/acetaminophen (P=0.001) and naproxen (P=0.048) compared with placebo. TTMP was significantly better for tramadol/acetaminophen and naproxen than placebo (P<0.001 to P=0.015) for walks on Day 1 after a single dose and on Day 3. CONCLUSIONS: This novel OA pain model was able to discriminate both tramadol/acetaminophen and naproxen from placebo after single and multiple doses. ClinicalTrials.gov identifier: NCT00772967.


Subject(s)
Acetaminophen/therapeutic use , Analgesics/therapeutic use , Naproxen/therapeutic use , Osteoarthritis, Knee/drug therapy , Pain/drug therapy , Tramadol/therapeutic use , Walking , Acetaminophen/administration & dosage , Aged , Analgesics/administration & dosage , Cross-Over Studies , Double-Blind Method , Drug Combinations , Exercise Test/methods , Female , Humans , Male , Middle Aged , Models, Biological , Osteoarthritis, Knee/physiopathology , Pain Measurement , Tramadol/administration & dosage
9.
Acta Radiol ; 50(2): 139-43, 2009 Mar.
Article in English | MEDLINE | ID: mdl-19101850

ABSTRACT

BACKGROUND: Fluoroscopically guided guidewire manipulations are readily available and inexpensive methods of correcting malfunctioning peritoneal dialysis catheters, with reported success rates ranging from 25% to 67%. PURPOSE: To improve the success rates of guidewire manipulations with a modified technique. MATERIAL AND METHODS: Using a stiff rod and a stiff wire under fluoroscopy guidance, catheters that had migrated were drawn back into the rectovesical pouch. An angular rod was used to lever the catheter downward, and the guidewire was used to push the catheter down. RESULTS: No complications developed, and immediate success was achieved in 13 of 14 interventions. With this technique, catheter patency in chronic ambulatory peritoneal dialysis (CAPD) patients (11/12) was higher than that of previously reported methods. Durable success was maintained in nine of 12 patients after a single intervention. All re-manipulations (2/2) were successful. CONCLUSION: Although used in only 14 interventions in 12 patients, the outcome was promising. This method is a safe and favorable alternative to other guidewire manipulations, based on absence of complications and high success.


Subject(s)
Foreign-Body Migration/therapy , Peritoneal Dialysis, Continuous Ambulatory/adverse effects , Peritoneal Dialysis, Continuous Ambulatory/instrumentation , Adolescent , Adult , Aged , Equipment Design , Equipment Failure , Female , Fluoroscopy , Humans , Male , Middle Aged , Radiography, Interventional , Treatment Outcome
10.
Transplant Proc ; 40(1): 22-6, 2008.
Article in English | MEDLINE | ID: mdl-18261538

ABSTRACT

Hepatic artery stenosis or thrombosis following liver transplant is a potentially life-threatening complication. Successful liver transplant depends on uncompromised hepatic arterial inflow. Early diagnosis and treatment of complications prolong graft survival. Interventional radiologic techniques are frequently used to treat hepatic artery complications. Twenty patients with hepatic artery stenoses (n = 11) or thromboses (n = 9) were included in this study. Eighteen of the 20 patients were successfully treated by stent placement. In 9 patients, early endovascular interventions were performed 1 to 7 days after surgery. Two patients were operated owing to the effects of dissection and bleeding from the hepatic artery. Repeat endovascular interventions were performed 10 times in 6 patients. Follow-up ranged from 5 months to 4.5 years. Nine patients with patent hepatic arteries died during follow-up owing to reasons unrelated to the hepatic artery interventions. In 3 patients, the stents became occluded at 3, 5, and 9 months after surgery but no clinical symptoms were present.


Subject(s)
Constriction, Pathologic/surgery , Hepatic Artery/surgery , Liver Transplantation/adverse effects , Stents , Thrombosis/surgery , Adolescent , Adult , Child , Female , Hepatic Artery/diagnostic imaging , Humans , Liver Diseases/surgery , Male , Middle Aged , Retrospective Studies , Ultrasonography
11.
Transplant Proc ; 39(4): 1178-80, 2007 May.
Article in English | MEDLINE | ID: mdl-17524925

ABSTRACT

AIMS: Splenic artery steal syndrome, a common complication in liver transplantation, is diagnosed by conventional angiography showing an enlarged splenic artery and by dynamic findings. The aim of this study was to determine multidetector computed tomographic angiography (MDCTA) findings of splenic artery steal syndrome to develop diagnostic criteria. MATERIALS AND METHODS: Ten patients were diagnosed as displaying splenic artery steal syndrome among 198 liver transplant patients. The diagnosis was confirmed by celiac angiography. In eight of them, MDCTA was performed. Axial and coronal maximum-intensity projection images were obtained in arterial and portal phases. We measured the diameter of the celiac trunk and of the splenic, left gastric, common hepatic, superior mesenteric artery, and transplant hepatic arteries. We also measured the diameter of the proximal and the distal segments of the abdominal aorta, along with the size of the spleen, the ratio of the splenic artery to the common hepatic artery, the ratio of splenic artery to transplant hepatic artery, the diameter of portal vein and superior mesenteric vein. The control group consisted of liver transplant patients with normal liver enzyme levels. We performed Student t test for statistical examination. RESULTS: The diameter of the splenic artery (P<.05), the size of the spleen (P<.01), and the ratio of the splenic to the transplant hepatic arteries (P<.05) was significant between the two groups. The diameter of the splenic artery was larger than 4 mm in all patients in the study group. CONCLUSIONS: Conventional angiography was mandatory for the diagnosis of splenic artery steal syndrome. MDCTA is a noninvasive method. Some computed tomography criteria are important for early diagnosis and treatment.


Subject(s)
Liver Transplantation , Splenic Artery/diagnostic imaging , Subclavian Steal Syndrome/surgery , Adolescent , Adult , Angiography , Child , Female , Humans , Male , Retrospective Studies , Splenic Artery/anatomy & histology , Tomography, X-Ray Computed
12.
Transplant Proc ; 38(2): 607-10, 2006 Mar.
Article in English | MEDLINE | ID: mdl-16549188

ABSTRACT

In pediatric liver transplantation postoperative diagnosis of complications is crucial for graft salvage. Multidetector computed tomography (MDCT) is a technique to evaluate complications. In this study we present nonvascular abdominal complications encountered in pediatric recipients after liver transplantation. We retrospectively examined 113 MDCT examinations in 43 pediatric patients who underwent liver transplantation between 1997 and 2005. Computed tomography (CT) examinations were made by a 16-detector multislice CT scanner. The pathological findings on CT images were: intraperitoneal free fluid, intrahepatic bile duct dilatation, graft liver infarction, perihepatic and intraperitoneal fluid collections (six biloma), colonic and/or intestinal dilatation, splenic infarction, perihepatic hematoma, right adrenal hemorrhage, perihepatic abscess, incisional hernia, intrahepatic biloma and periportal collar. In one patient intestinal hemorrhage was suspected. Intestinal perforation was suspected in three patients. Among these three patients, one patient died before any surgical intervention. In two patients the diagnosis was confirmed at surgery. In pediatric patients, the short examination time, brief sedation duration, and high-resolution images make MDCT an effective radiological method to evaluate nonvascular transplant complications.


Subject(s)
Liver Transplantation/adverse effects , Postoperative Complications/diagnostic imaging , Adolescent , Child , Child, Preschool , Female , Humans , Infant , Liver Transplantation/pathology , Male , Postoperative Complications/pathology , Retrospective Studies , Tomography, X-Ray Computed/methods
14.
Exp Neurol ; 182(1): 180-5, 2003 Jul.
Article in English | MEDLINE | ID: mdl-12821388

ABSTRACT

The addition of polysialic acid (PSA) to neural cell adhesion molecule (NCAM) facilitates axon growth. Here we use Western blots and immunohistochemistry to examine expression of PSA-NCAM during optic nerve regeneration. In lizard, retinal ganglion cell axons become transiently PSA-NCAM positive. By contrast, goldfish RGC axons are PSA-NCAM negative both in normal animals and throughout regeneration with the exception of a PSA-NCAM-positive fascicle arising from newly generated RGCs. Transient sialylation of NCAM in lizard may assist regeneration in the nonpermissive reptilian visual pathway and facilitate the reestablishment of a crude topographic map; down-regulation in the long term may contribute to the breakdown in topography. The lack of sialylation in goldfish presumably reflects the permissive nature of the substrate allowing axon regeneration and the successful reestablishment of a topographic map.


Subject(s)
Goldfish/physiology , Lizards/physiology , Nerve Regeneration/physiology , Neural Cell Adhesion Molecule L1/metabolism , Optic Nerve/physiology , Sialic Acids/metabolism , Animals , Axons/metabolism , Blotting, Western , Immunohistochemistry , Optic Nerve/metabolism , Retinal Ganglion Cells/cytology , Retinal Ganglion Cells/metabolism , Species Specificity , Up-Regulation/physiology
15.
J Virol ; 75(19): 8909-16, 2001 Oct.
Article in English | MEDLINE | ID: mdl-11533154

ABSTRACT

Activation of cellular interferon-stimulated genes (ISGs) after infection with herpes simplex virus type 1 (HSV-1) or human cytomegalovirus (HCMV) was investigated. The level of ISG54-specific RNA in human fetal lung (HFL) or human foreskin (BJ) fibroblasts increased substantially after infection with either virus in the presence of cycloheximide. HSV-1 particles lacking glycoprotein D or glycoprotein H failed to induce ISG54-specific RNA synthesis, demonstrating that entry of virus particles rather than binding of virions to the cell surface was required for the effect. A DNA-binding complex that recognized an interferon-responsive sequence motif was induced upon infection with HSV-1 or HCMV in the presence of cycloheximide, and the complex was shown to contain the cell proteins interferon response factor 3 (IRF-3) and CREB-binding protein. IRF-3 was modified after infection with HSV-1 or HCMV to a form of lower electrophoretic mobility, consistent with phosphorylation. De novo transcription of viral or cellular genes was not required for the activation of IRF-3, since the effect was not sensitive to inhibition by actinomycin D. Infection of HFL fibroblasts with HSV-1 under conditions in which viral replication proceeded normally resulted in severely reduced levels of the IRF-3-containing complex, defining the activation of IRF-3 as a target for viral interference with ISG induction. In BJ fibroblasts, however, significant activation of IRF-3 was detected even when the viral gene expression program progressed to later stages, demonstrating that the degree of inhibition of the response was dependent on host cell type. As a consequence of IRF-3 activation, endogenous interferon was released from BJ cells and was capable of triggering the appropriate signal transduction pathway in both infected and uninfected cells. Activation of ISG54-specific RNA synthesis was not detected after infection of human U-373MG glioblastoma cells, showing that the induction of the response by infection is cell type dependent.


Subject(s)
Cytomegalovirus Infections/metabolism , Cytomegalovirus/physiology , Herpes Simplex/metabolism , Herpesvirus 1, Human/physiology , Transcription Factors/metabolism , Apoptosis Regulatory Proteins , Cell Line , Humans , RNA-Binding Proteins , Virus Replication
16.
Vision Res ; 41(14): 1765-70, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11369040

ABSTRACT

Electrophysiological recording demonstrated that visuo-tectal projections are topographically organised after optic nerve regeneration in aged Xenopus laevis. 3H-thymidine autoradiography confirmed previous reports [Taylor, Lack, & Easter, Eur. Journal of Neuroscience 1 (1989) 626-638] that cell division had already ceased at the retinal ciliary margin. The results demonstrate that, contrary to a previous suggestion [Holder & Clarke, Trends in Neuroscience 11 (1988) 94-99], continued neurogenesis is not a pre-requisite for the re-establishment of appropriate connections with target cells.


Subject(s)
Nerve Regeneration/physiology , Optic Nerve/physiology , Aging/physiology , Animals , Autoradiography , Axotomy , Cell Division/physiology , Cilia/physiology , Electrophysiology , Optic Nerve/cytology , Xenopus laevis
17.
Neuroscience ; 102(3): 647-54, 2001.
Article in English | MEDLINE | ID: mdl-11226701

ABSTRACT

In the lizard, Ctenophorus ornatus, the optic nerve regenerates but animals remain blind via the experimental eye, presumably as a result of axons failing to consolidate a retinotopic map in the optic tectum. Here we have examined immunohistochemically the expression of the growth-associated protein GAP-43 and the low-molecular-weight intermediate filament protein gefiltin, up to one year after optic nerve crush. Both proteins were found to be permanently up-regulated, suggesting that regenerating axons are held in a permanent state of re-growth. We speculate that, in the lizard, the continued expression of GAP-43 and the failure to switch from the expression of low- to high-molecular-weight intermediate filament proteins are associated with the inability to consolidate a retinotopic projection.


Subject(s)
Axons/physiology , Fish Proteins , GAP-43 Protein/genetics , Gene Expression Regulation/physiology , Intermediate Filament Proteins/genetics , Nerve Regeneration/physiology , Optic Nerve/physiology , Animals , Axons/ultrastructure , GAP-43 Protein/analysis , Immunohistochemistry , In Situ Hybridization , Intermediate Filament Proteins/analysis , Lizards , Nerve Crush , Nerve Fibers/physiology , Neurons/physiology , Optic Nerve/cytology , Superior Colliculi/physiology , Time Factors
18.
Brain Behav Evol ; 58(1): 15-27, 2001.
Article in English | MEDLINE | ID: mdl-11799275

ABSTRACT

We examined the retinal ganglion cell layer of the dromedary camel, Camelus dromedarius. We have estimated that there are 8 million neurons in the ganglion cell layer of this large retina (mean area of 2,300 mm(-2)). However, only approximately 1 million are considered to be ganglion cells. The ganglion cells are arranged as two areas of high cell density, one in the temporal and one in the nasal retina. Densities of ganglion cells between these two high density regions is much lower, often less than 100 per mm(-2). In between these two high density regions, on the nasal side of the optic nerve head, is a unique and dense vertical streak of mostly non-ganglion cells; the function of this specialization is unknown. On the basis of ganglion cell density we estimate that the peak acuity in the dromedary camel is about 10 and 9.5 cycles per degree in the temporal and nasal high density regions respectively and falls to 2-3 cycles per degree in the central retina. Behavioral acuity was estimated for one bactrian camel and was found to be approximately 10 cyc deg(-1). The camel has a retina with a mean thickness of 104 microm, less than the 143 microm thickness that has previously been thought to be necessary for a retinal vasculature. Nevertheless, there is an extensive vitreal vasculature that does not appear to spare any retinal region.


Subject(s)
Camelus/anatomy & histology , Retina/cytology , Visual Acuity , Animals , Camelus/physiology , Cell Count , Retina/ultrastructure , Retinal Ganglion Cells/cytology , Retinal Ganglion Cells/ultrastructure , Retinal Vessels
19.
Philos Trans R Soc Lond B Biol Sci ; 355(1401): 1183-6, 2000 Sep 29.
Article in English | MEDLINE | ID: mdl-11079394

ABSTRACT

The topography of the neurons in the retinal ganglion cell layer of juvenile black bream Acanthopagrus butcheri changes during development. The region of high cell density the area centralis (AC), relocates from a temporal (central) to a dorsal (peripheral) position within the dorso-temporal retinal quadrant. To ascertain whether the differences in the position of the AC during development are related to feeding behaviour, we monitored fishes that were given a choice of food. A range of feeding behaviour patterns was recorded in individual fishes. The smallest fishes (8-15 mm standard length (SL)) took live food from the water column. Following weaning onto pellets, fishes exhibited a preference for taking food from either the substrate or the surface (but not both). When greater than 20 mm SL, a number of individuals then divided their time between surface and substrate feeding before all fishes became exclusive benthic feeders at a stage between 50 and 80 mm SL. Three individual fishes, for which behaviour patterns were categorized, were killed and the topography of the retinal ganglion cell layer analysed. A range of positions for the AC was found with the smallest fish (12 mm SL) possessing a region of high cell density in the temporal retina. In a larger fish (70 mm SL), feeding from both the substrate and the surface, the AC was found in an intermediate dorso-temporal position. The AC of a fish (51 mm SL) preferentially taking food from the substrate was located in a dorsal position.


Subject(s)
Feeding Behavior/physiology , Retina/anatomy & histology , Sea Bream/anatomy & histology , Sea Bream/physiology , Animals , Artemia , Vision, Ocular/physiology
20.
Anat Rec ; 260(2): 124-31, 2000 10 01.
Article in English | MEDLINE | ID: mdl-10993949

ABSTRACT

Literature assessing whether or not neurons (retinal ganglion cells and displaced amacrine cells) are lost from the retinal ganglion cell layer in mammals with age is still controversial, some studies finding a decrease in cell density and others not. To date there have been no studies estimating the total number of neurons in the retinal ganglion cell layer of humans throughout life. Recent studies have concentrated on the macular region and examined cell densities, which are reported to decrease during aging. In a study of the human retinal pigment epithelium (RPE), we showed that, while RPE cell number does not change, cell density increases significantly in central temporal retina (macular region) as the retina ages. We speculated that the increase in density represents a "drawing together" of the retinal sheet to maintain high cell densities, in this region of the neural retina, in the face of presumed cell loss from the ganglion cell layer due to aging. Here, therefore, we have sampled the entire ganglion cell layer of the human retina and estimated total neuron numbers in 12 retinae aged from 16 to 77 years. Human retinae, fixed in formalin, were obtained from the Queensland Eye Bank and whole-mounted, ganglion cell layer uppermost. The total number of neurons was lower in the older than younger retinae and neuronal density was lower in most retinal regions in older retinae. Retinal area increased with age and neuronal density fell throughout the retina with a mean reduction of 0.53% per year. However, the percentage reduction in density was much lower for the macular region, with a value of 0.29% per year. It is possible that this lesser reduction in cell density in the macula is a result of the drawing together of the retinal sheet in this region as we speculated from RPE data.


Subject(s)
Cell Death/physiology , Retina/growth & development , Retinal Ganglion Cells/cytology , Adolescent , Adult , Age Factors , Aged , Cell Count , Cell Size/physiology , Female , Humans , Male , Middle Aged , Retina/cytology
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