International Consensus on drug allergy.

When drug reactions resembling allergy occur, they are called drug hypersensitivity reactions (DHRs) before showing the evidence of either drug-specific antibodies or T cells. DHRs may be allergic or nonallergic in nature, with drug allergies being immunologically mediated DHRs. These reactions are typically unpredictable. They can be life-threatening, may require or prolong hospitalization, and may necessitate changes in subsequent therapy. Both underdiagnosis (due to under-reporting) and overdiagnosis (due to an overuse of the term 'allergy') are common. A definitive diagnosis of such reactions is required in order to institute adequate treatment options and proper preventive measures. Misclassification based solely on the DHR history without further testing may affect treatment options, result in adverse consequences, and lead to the use of more-expensive or less-effective drugs, in contrast to patients who had undergone a complete drug allergy workup. Several guidelines and/or consensus documents on general or specific drug class-induced DHRs are available to support the medical decision process. The use of standardized systematic approaches for the diagnosis and management of DHRs carries the potential to improve outcomes and should thus be disseminated and implemented. Consequently, the International Collaboration in Asthma, Allergy and Immunology (iCAALL), formed by the European Academy of Allergy and Clinical Immunology (EAACI), the American Academy of Allergy, Asthma and Immunology (AAAAI), the American College of Allergy, Asthma and Immunology (ACAAI), and the World Allergy Organization (WAO), has decided to issue an International CONsensus (ICON) on drug allergy. The purpose of this document is to highlight the key messages that are common to many of the existing guidelines, while critically reviewing and commenting on any differences and deficiencies of evidence, thus providing a comprehensive reference document for the diagnosis and management of DHRs.

Grading quality of evidence and strength of recommendations in clinical practice guidelines part 3 of 3. The GRADE approach to developing recommendations.

This is the third and last article in the series about the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to grading the quality of evidence and the strength of recommendations in clinical practice guidelines and its application in the field of allergy. We describe the factors that influence the strength of recommendations about the use of diagnostic, preventive and therapeutic interventions: the balance of desirable and undesirable consequences, the quality of a body of evidence related to a decision, patients' values and preferences, and considerations of resource use. We provide examples from two recently developed guidelines in the field of allergy that applied the GRADE approach. The main advantages of this approach are the focus on patient important outcomes, explicit consideration of patients' values and preferences, the systematic approach to collecting the evidence, the clear separation of the concepts of quality of evidence and strength of recommendations, and transparent reporting of the decision process. The focus on transparency facilitates understanding and implementation and should empower patients, clinicians and other health care professionals to make informed choices.

Grading quality of evidence and strength of recommendations in clinical practice guidelines: Part 2 of 3. The GRADE approach to grading quality of evidence about diagnostic tests and strategies.

The GRADE approach to grading the quality of evidence and strength of recommendations provides a comprehensive and transparent approach for developing clinical recommendations about using diagnostic tests or diagnostic strategies. Although grading the quality of evidence and strength of recommendations about using tests shares the logic of grading recommendations for treatment, it presents unique challenges. Guideline panels and clinicians should be alert to these special challenges when using the evidence about the accuracy of tests as the basis for clinical decisions. In the GRADE system, valid diagnostic accuracy studies can provide high quality evidence of test accuracy. However, such studies often provide only low quality evidence for the development of recommendations about diagnostic testing, as test accuracy is a surrogate for patient-important outcomes at best. Inferring from data on accuracy that using a test improves outcomes that are important to patients requires availability of an effective treatment, improved patients' wellbeing through prognostic information, or - by excluding an ominous diagnosis - reduction of anxiety and the opportunity for earlier search for an alternative diagnosis for which beneficial treatment can be available. Assessing the directness of evidence supporting the use of a diagnostic test requires judgments about the relationship between test results and patient-important consequences. Well-designed and conducted studies of allergy tests in parallel with efforts to evaluate allergy treatments critically will encourage improved guideline development for allergic diseases.

Glycosylphosphatidyl inositol-anchored proteins and fyn kinase assemble in noncaveolar plasma membrane microdomains defined by reggie-1 and -2.

Using confocal laser scanning and double immunogold electron microscopy, we demonstrate that reggie-1 and -2 are colocalized in < or =0.1-microm plasma membrane microdomains of neurons and astrocytes. In astrocytes, reggie-1 and -2 do not occur in caveolae but clearly outside these structures. Microscopy and coimmunoprecipitation show that reggie-1 and -2 are associated with fyn kinase and with the glycosylphosphatidyl inositol-anchored proteins Thy-1 and F3 that, when activated by antibody cross-linking, selectively copatch with reggie. Jurkat cells, after cross-linking of Thy-1 or GM1 (with the use of cholera toxin), exhibit substantial colocalization of reggie-1 and -2 with Thy-1, GM1, the T-cell receptor complex and fyn. This, and the accumulation of reggie proteins in detergent-resistant membrane fractions containing F3, Thy-1, and fyn imparts to reggie-1 and -2 properties of raft-associated proteins. It also suggests that reggie-1 and -2 participate in the formation of signal transduction centers. In addition, we find reggie-1 and -2 in endolysosomes. In Jurkat cells, reggie-1 and -2 together with fyn and Thy-1 increase in endolysosomes concurrent with a decrease at the plasma membrane. Thus, reggie-1 and -2 define raft-related microdomain signaling centers in neurons and T cells, and the protein complex involved in signaling becomes subject to degradation.

Localisation and expression of a myelin associated neurite inhibitor, Nogo-A and its receptor Nogo-receptor by mammalian CNS cells.

Axon regeneration failure in the adult mammalian central nervous system (CNS) is partly due to inhibitory molecules associated with myelin. The Nogo receptor (NgR) plays a role in this process through an extraordinary degree of cross reactivity with three structurally unrelated myelin-associated inhibitory ligands namely; Nogo-A, myelin associated glycoprotein (MAG) and oligodendrocyte myelin glycoprotein (OMgp). The major aim of the study was to investigate and explore the cellular localisation and expression pattern of NgR and Nogo-A in the mammalian nervous system. We therefore generated a rabbit polyclonal anti-NgR antibody from the leucine rich repeat (LRR) No. 9 domain of the NgR polypeptide chain. Together with a commercially available polyclonal antibody specific for NgR, and in conjunction with double labeling immunofluorescence methods on cryosections and cell cultures, NgR immunoreactivity was observed in the CNS and dorsal root ganglia (DRG). In cellular populations, it was confined to neuronal cell bodies and their processes. NgR was also localised on the surface of extending DRG intact axons and growth cones in live staining experiments. Nogo-A, a member of the reticulon family protein, was widely distributed in the mammalian brain, spinal cord, and DRG. Intense Nogo-A immunoreactivity was also detected in oligodendrocyte cell bodies and their myelin sheaths in nerve fibre tracts of the CNS. Furthermore, numerous populations of neurons in the brain and spinal cord expressed Nogo-A to a variable extent in their cell bodies and neurites, suggesting additional, as-yet-unknown, functions of this protein. These results confirm results obtained by other researchers with different sets of antibodies. However, they also raise the question of the mechanism and circumstances under which NgR interacts with Nogo-A, as the latter appears to be confined to the cytoplasm and can therefore not be expected to bind NgR on the axon surface.

Guidelines and realities of asthma management. The Philadelphia story.

BACKGROUND: Guidelines from the National Heart, Lung, and Blood Institute, Bethesda, Md, have encouraged more frequent use of inhaled steroids in asthma management. OBJECTIVES: To determine (1) whether prescription rates for inhaled steroids have increased compared with prescriptions for bronchodilators and (2) significant associations of demographic factors with bronchodilator-inhaled steroid prescription ratios and with rates of inhaled steroid prescriptions. DESIGN: Cross-sectional analysis of monthly bronchodilator and inhaled steroid prescription rates, numbers and types of asthma care providers, and demographic factors. SETTING: Philadelphia, Pa. MEASUREMENTS: Using univariate and multivariate analyses, bronchodilator and inhaled steroid prescription rates were determined for 45 ZIP codes and studied for associations with race and ethnicity, poverty, educational attainment, marital status, gender, total numbers of asthma drug prescriptions, and numbers and types of asthma care providers. RESULTS: Monthly bronchodilator-inhaled steroid prescription ratios increased from July 1991 to June 1993 (P < .001). Prescription rates for inhaled steroids and inhaled bronchodilators declined, but rates for oral bronchodilators (beta-agonists and theophylline) increased. By stepwise multiple regression, higher bronchodilator-inhaled steroid prescription ratios and lower inhaled steroid prescription rates were each significantly associated with ZIP codes in which greater proportions of residents lacked a high school diploma (P < .001); associations that approached statistical significance were found for higher bronchodilator-inhaled steroid ratios and fewer asthma care providers (P = .05) and for lower inhaled steroid prescription rates and lower proportions of asthma specialists (P = .04). CONCLUSIONS: In Philadelphia, a gap exists between optimal asthma drug prescribing and actual prescribing patterns that has widened from July 1991 to June 1993. Underuse of inhaled steroids is most closely associated with lower educational attainment, suggesting that interventions that include addressing the special asthma care needs of a low-literacy population will be required to achieve the goals of the National Asthma Education Program.

Elevated risk of anaphylactoid reaction from radiographic contrast media is associated with both beta-blocker exposure and cardiovascular disorders.

BACKGROUND: A case-control study, with both retrospective and concurrent subject selection, was performed (1) to determine whether greater risk for anaphylactoid reaction from contrast media associated with beta-blocker exposure reflects presence, or is independent of underlying cardiovascular disorder; and (2) to characterize further the risk of anaphylactoid reaction from contrast media in patients with cardiovascular disorders and patients with asthma. METHODS: Adverse reactions from intravenous contrast media were recorded in accordance with quality assurance guidelines. Anaphylactoid reactions were classified as mild to moderate (urticaria/angioedema), severe (stridor, bronchospasm, or hypotension), or major and life-threatening (hypotension with or without the need for subsequent hospitalization). Medical records from reactors were compared with those from matched (gender, age, date, and type of contrast study) controls who received conventional contrast media without adverse reaction. RESULTS: Of 34,371 intravenous contrast media procedures performed, 122 anaphylactoid reactions were recorded. The risk of anaphylactoid reaction was significantly associated with asthma (odds ratio [OR], 8.74; 95% confidence interval [CI], 2.36 to 32.35; P = .0012). The risk of bronchospasm was associated with beta-blocker exposure (OR, 3.73; 95% CI, 1.18 to 11.75; P = .025) and with asthma (OR, 16.39; 95% CI, 4.30 to 62.46; P = .0001). The risk of major and life-threatening reaction was associated with the presence of cardiovascular disorder (OR, 7.71; 95% CI, 1.04 to 57.23; P = .046). Among patients with severe reactions, the risk of hospitalization was elevated by the presence of cardiovascular disorder (P = .001), exposure to beta-blockers (OR, 7.67; 95% CI, 1.79 to 32.85; P = .029), or asthma (OR, 20.7; 95% CI, 1.21 to 355.55; P = .065). Although beta-blocker exposure and the presence of cardiovascular disorder were highly associated (chi 2 = 49, P < .001), a greater risk of bronchospasm with severe reaction was observed in nonasthmatic patients with cardiovascular disorders receiving beta-blockers (OR, 15.75; P = .023). Among reactors with asthma, receiving beta-blockers, or with a cardiovascular disorder, 60.8% (31/51) experienced severe anaphylactoid reactions, compared with 35.2% (25/71) of patients without these risk factors (OR, 3.62; P = .005). CONCLUSIONS: beta-Blocker exposure and cardiovascular disorder are both statistically significant risk factors for severe anaphylactoid reaction from contrast media. Thus, patients receiving beta-adrenergic blockers and patients with asthma, on the basis of greater risk for bronchospasm, and patients with cardiovascular disorders, on the basis of elevated risk of major and life-threatening reaction, are appropriate target populations for risk reduction measures before receiving intravenous infusion of contrast media.

Omalizumab is efficacious for management of recalcitrant, antihistamine-resistant chronic urticaria.

Chronic urticaria continues to be a challenging condition for both patients and physicians. Despite improved understanding of chronic urticaria, many patients continue to experience ongoing symptoms and impaired quality of life. Omalizumab is a recombinant humanized monoclonal antibody that binds to the domain at which IgE binds to the high-affinity IgE receptor on mast cells and basophils. The efficacy of omalizumab for antihistamine-resistant chronic urticaria has been demonstrated in several randomized controlled trials as well as observational studies. Omalizumab is generally well tolerated, and is associated with less potential for harm compared with other therapeutic alternatives (e.g., calcineurin inhibitors) for recalcitrant chronic urticaria. Omalizumab has become the best-studied agent for treatment of antihistamine-resistant chronic urticaria, and the agent for which the data in support of its efficacy is most methodologically sound. Omalizumab is an effective therapeutic option for patients with recalcitrant chronic urticaria.

Theophylline improves measurements of respiratory muscle efficiency.

To determine the effect of theophylline on respiratory muscle efficiency (RME), 12 normal subjects were given theophylline vs placebo in a double-blind, randomized crossover protocol. Spirometry, resting energy expenditure, minute ventilation, RME and oxygen cost of breathing were measured at baseline, after taking theophylline, and after placebo. RME was calculated by dividing the added work required to breathe through a threshold load by the added energy consumed during loaded breathing. Oxygen cost of breathing was calculated by dividing the increase in oxygen consumption induced by breathing an air/carbon dioxide mixture by the associated increase in minute ventilation. RME increased from 3.3 +/- 1.6% at baseline to 7.9 +/- 3.2% after theophylline (p < 0.01) but did not change significantly after placebo (4.8 +/- 2.4%). Oxygen cost of breathing decreased from 3.9 +/- 2.4 mL O2 per liter at baseline to 1.7 +/- 0.7 mL O2 per liter after theophylline (p < 0.05) but did not change significantly after placebo (2.8 +/- 1.3 mL O2 per liter). Theophylline use was also associated with an 18% increase in minute ventilation (p < 0.01) and a 15.7% increase in resting energy expenditure (p < 0.01). Theophylline improves measured RME and reduces oxygen cost of breathing in normal subjects. These effects are offset by increases in resting energy expenditure and minute ventilation.

Exercise-induced bronchospasm in high school athletes via a free running test: incidence and epidemiology.

BACKGROUND: Exercise-induced bronchospasm (EIB) affects up to 35% of athletes and up to 90% of asthmatics. Asthma morbidity and mortality have increased over the past several decades among residents of Philadelphia, PA. It is possible that a simple free running test for EIB may serve as a tool to study the factors contributing to recent trends in asthma, and to screen for asthma in athletes in the urban setting. OBJECTIVES: The purposes of this study were to (1) assess a free running test to screen for EIB, and (2) examine prevalence of and epidemiologic factors associated with EIB in high school athletes. DESIGN: Cross-sectional observational study on the incidence and risk factors for EIB. To validate our method and criteria for the diagnosis of EIB, a repeat test was performed on a portion of the athletes. In a randomized single-blinded fashion, 15 athletes who had demonstrated EIB initially received albuterol or placebo prior to a repeat exercise test. SETTING: Community high school athletic facilities. PARTICIPANTS: We studied 238 male high school varsity football players. INTERVENTION: All athletes underwent an acquaintance session with a questionnaire, followed by a 1-mile outdoor run (6 to 8 mins). MEASUREMENTS: Peak expiratory flow (PEF) measurements were determined prior to and 5, 15, and 30 min after exercise. Heart rates (HRs) and dyspnea scores were measured. EIB was defined as a decrease of 15% in PEF at any time point after exercise. Associations of EIB with demographic factors were assessed by univariate and multivariate analyses. RESULTS: Two hundred thirty-eight athletes participated: 92 European-Americans (EA), 140 African-Americans (AA), 5 Hispanics, and 1 Native American. Mean age was 16+/-1 years. Average HR postexercise was 156+/-24 beats/min. Twenty-four (10%) reported a history of treated asthma. The prevalence of EIB among the remaining 214 athletes was 19 of 214 (9%). The rate of EIB among AA athletes was higher than among EA athletes: (17/126 [13%] AA vs 2/82 [2%] EA, p = 0.01). During the validation portion of the study, the placebo-treated group (n = 7) demonstrated a consistent drop in PEF after exercise on repeat testing, with a 16+/-5% fall in PEF on initial testing and a 14+/-13 drop with placebo. In contrast, the fall in airflow in the albuterol-treated athletes (n = 8) following exercise reversed with albuterol treatment, from a 15+/-6% fall in PEF at initial testing to an increase in PEF of 6+/-9% from baseline following albuterol administration. A history of wheezing (p < 0.001), residence in a poverty area (p < 0.0001), race (p = 0.01), remote history of asthma (p < 0.001), and absolute water content of the air on the day tested (p = 0.04) were significantly associated with EIB. By stepwise regression, EIB was most closely associated with a history of wheezing (p = 0.001) and poverty area residence (p = 0.003). CONCLUSIONS: Our findings indicate a substantial rate of unrecognized EIB exists among urban varsity athletes, and suggest that active screening for EIB, especially for students residing in poverty areas, may be indicated to identify individuals at risk for EIB and asthma.

Anaphylactoid and anaphylactic reactions. Hazards of beta-blockers.

Studies have demonstrated greater hazards associated with anaphylaxis in patients receiving beta-blockers. Serious anaphylaxis is more frequent. Evidence suggests this occurs via modulation of adenylate cyclase, which can influence release of anaphylactogenic mediators. Treatment of anaphylaxis in patients exposed to beta-blockers is complicated because therapeutic administration of epinephrine (adrenaline) may be ineffective or promote undesired alpha-adrenergic and vagotonic effects. Risk reduction efforts should be considered for patients receiving beta-blockers who are prone to experience anaphylaxis.

Structural requirements for the inhibition of human monocyte carboxylesterase by organophosphorus compounds.

Human blood monocyte carboxylesterase (CBE) is inhibited by a variety of organophosphorus compounds including arylphosphates and arylphosphites and some alkylphosphites. Triphenyl phosphate and triphenyl phosphite with Ki values of 8 x 10(-9) M and 4.8 x 10(-8) M, respectively, are the most potent inhibitors of this enzyme evaluated by this study. The arylphosphates vary in their capacity to inhibit carboxylesterase activity. Diphenyl phosphate with its strong negative charge is not a potent inhibitor (Ki = 1 x 10(-4) M), whereas if its negative charge is neutralized, as in diphenyl methyl phosphate, its capacity to inhibit carboxylesterase is significantly increased. Compounds with increased bulk, such as trinaphthyl phosphate, only inhibit the enzyme at concentrations of 10(-5) M or greater. Arylphosphites have inhibitory capacities similar to the arylphosphates. Alkylphosphites (tributyl phosphite/triethyl phosphite) inhibit carboxylesterase activity, whereas alkylphosphates (tributyl phosphate/triethyl phosphate) have no inhibitory effect. Arylphosphines and arylphosphine oxides do not inhibit carboxylesterase activity. This study demonstrates that organophosphates and organophosphites are relatively effective inhibitors of human monocyte CBE activity with the exception of the alkylphosphates which have no inhibitory activity. We conclude that molecular bulk and charge have a significant role in determining the potency of organophosphorus inhibitors of monocyte CBE. The observed variations in the degree of esterase inhibition by organophosphorus compounds as well as the differences in the pathological expression of neuropathic disorders associated with such chemicals suggest that different esterase enzymes derived from the family of esterase genes may mediate the different neuropathies observed with organophosphorus exposures. Such data also provide the rationale for the kinetic analyses of esterases and the design of non-toxic organophosphorus compounds with low or no monocyte CBE inhibitory capacity to reduce the potential of these commonly used chemicals for human toxicity.

Patellar resurfacing versus retention in total knee arthroplasty.

We studied 40 patients in whom the patella was not severely deformed and who were undergoing primary total knee arthroplasty (TKA) for osteoarthritis by one surgeon using one type of prosthesis. They were randomly allocated either to have the patella retained or resurfaced with a cemented, all-polyethylene component regardless of the state of the patellar articular cartilage. Apart from removal of osteophytes, no surgery was undertaken on the retained patellae. All 38 surviving patients were evaluated at three years using the HSS knee score and a new, specifically designed Patellar score (maximum score of 30). No TKA was revised, but two patients in the resurfacing group had a further unrelated procedure. The mean HSS and Patellar scores at follow-up were 89 and 28 in the patellar retention group and 83 and 26 in the patellar resurfacing group. Statistically significant lower scores for both were recorded in women and in heavier patients. Stair-climbing ability was significantly better in the retention group. Although there were no complications related to patellar resurfacing, in the medium term we did not find any significant benefit from resurfacing the patella during TKA for osteoarthritis if it was not severely deformed.

Treatment of osteoporosis: missed opportunities in the hospital fracture clinic.

AIM: To identify what proportion of patients who, having sustained an initial distal radial fragility fracture and a subsequent femoral neck fracture, had had their osteoporosis addressed in the interval between the two events. PATIENTS AND METHODS: The hospital electronic information system was used to identify all patients aged over 50 years treated for a distal radial fracture, in our fracture clinic, between 1995-2000. In addition all patients admitted to our hospital, during the same time period, with a femoral neck fracture were identified. RESULTS: A study cohort of 74 patients were identified. The proportion of patients who received investigation of, or treatment for, osteoporosis between their wrist and femoral neck fracture was 8% whereas 84% did not. CONCLUSIONS: Current mechanisms for identifying patients with osteoporosis before they sustain a femoral neck fracture are inadequate.

Osteoid osteoma of the lunate--a case report.

We report a rare case of an osteoid osteoma of the lunate bone in a young lady who presented to us with chronic wrist pain. She was treated by excision and cancellous bone grafting of the lesion with complete resolution of symptoms.

The use of the Ma-Griffith technique for percutaneous repair of fresh ruptured tendo Achillis.

All patients treated for a rupture of the Achilles tendon by the technique of percutaneous repair were identified from a five year period up to 1987. A review of the patients and results of this technique was undertaken using a clinical grading system. Review was conducted between 18 and 81 months following the injury. Of 38 patients followed up, 71% achieved good results and only 8% poor results. The re-rupture rate for this series was 8%. Sural nerve involvement (13%) was found to be a troublesome complication. During the period under study, a modification to the technique was introduced which abolished this complication. We present our results and describe the modification to the technique. The importance of the use of nonabsorbable sutures is emphasized.

Resveratrol extends lifespan and preserves glia but not neurons of the Nothobranchius guentheri optic tectum.

Resveratrol is reported as having neuroprotective properties, however, much of this reputation has come from research using disease and injury models of neurodegeneration and not neurodegenerative-ageing. The results published here pertain to the affect resveratrol has on neurodegenerative-ageing. Resveratrol had previously been used to extend the lifespan of Nothobranchius furzeri wherein it preserved cognition and reduced ageing-associated neurodegeneration. No cell-type specific antibodies were then identified which could be used to investigate the nature of the neurodegeneration or resveratrols effect on CNS cells. Using wholemounts stained with SMI31 anti-phospho-neurolament, GA-5 and DAKO Z0334 anti-GFAP antibodies, E587 antiserum against NCAMs and anti-tenascin-R antibodies we determined what cellular changes occurred with age in the optic tectum of Nothobranchius guentheri. We show that resveratrol-treatment extended the lifespan of N. guentheri but did not preserve neuron density of the optic tectum stratum griseum superciale even though it did reduce the proportion of degenerate (SMI31 antigen accumulating) neurons in the optic tectum. Resveratrol-treatment did prevent the ageing-dependent loss of radial glia lining the optic tectum of N. guentheri. The ageing-related loss of NCAM expression and tenascin-R expressing perineuronal nets was also prevented by resveratrol-treatment. Glial and perineuronal density as well as NCAM expression appear to correlate well with age. These results suggest that the anti-ageing properties of resveratrol in vertebrates may be unrelated to the protection of neurons.

Neuronal and glial differentiation during lizard (Gallotia galloti) visual system ontogeny.

We studied the histogenesis of the lizard visual system (E30 to adulthood) by using a selection of immunohistochemical markers that had proved relevant for other vertebrates. By E30, the Pax6(+) pseudostratified retinal epithelium shows few newborn retinal ganglion cells (RGCs) in the centrodorsal region expressing neuron- and synaptic-specific markers such as betaIII-tubulin (Tuj1), synaptic vesicle protein-2 (SV2), and vesicular glutamate transporter-1 (VGLUT1). Concurrently, pioneer RGC axons run among the Pax2(+) astroglia in the optic nerve and reach the superficial optic tectum. Between E30 and E35, the optic chiasm and optic tract remain acellular, but the latter contains radial processes with subpial endfeet expressing vimentin (Vim). From E35, neuron- and synaptic-specific stainings spread in the retina and optic tectum, whereas retinal Pax6, and Tuj1/SV2 in RGC axons decrease. Müller glia and abundant optic nerve glia express a variety of glia-specific markers until adulthood. Subpopulations of optic nerve glia are also VGLUT1(+) and cluster differentiation-44 (CD44)-positive but cytokeratin-negative, unlike the case in other regeneration-competent species. Specifically, coexpression of CD44/Vim and glutamine synthetase (GS)/VGLUT1 reflects glial specialization, insofar as most CD44(+) glia are GS(-). In the adult optic tract and tectum, radial glia and free astroglia coexist. The latter show different immunocharacterization (Pax2(-)/CD44(-) /Vim(-)) compared with that in the optic nerve. We conclude that upregulation of Tuj1 and SV2 is required for axonal outgrowth and search for appropriate targets, whereas Pax2(+) optic nerve astroglia and Vim(+) radial glia may aid in early axonal guidance. Spontaneous axonal regrowth seems to succeed despite the heterogeneous mammalian-like glial environment in the lizard optic nerve.

Expression of BDNF and NT-3 during the ontogeny and regeneration of the lacertidian (Gallotia galloti) visual system.

Retinal ganglion cell (RGC) axons regrow spontaneously after optic nerve (ON) transection in G. galloti. Because brain-derived neurotrophic factor (BDNF) is considered the major neurotrophin participating in vertebrate visual system development and promotes RGC survival, we investigated its distribution using dual-labeling immunohistochemistry for neuronal and glial markers. We examined the developing and regenerating lizard visual system at 1, 3, 6, 9, and 12 months postlesion to comparatively evaluate BDNF expression patterns. BDNF was detected from midembryonic stages (E35) in both retinal plexiform layers, and in radial glial processes in the tectum. Moreover, RGC axon staining was detected at late prenatal stages (E39), showing a transient punctate staining which progressed in a temporo-spatial pattern that was similar to myelination. Strong expression in RGC axons was maintained in adults. However, transient downregulation of BDNF staining occurred on the experimental side one month after ON transection followed by a gradual recovery with extensive punctate/swelling distribution and persistent upregulation at 12 months. Conversely, quantitative PCR analysis for 1 and 12 months regenerate lizards showed downregulation of the ratio of BDNF mRNA expression at 12 months and nonsignificant changes of NT-3 transcripts. In summary, we demonstrate that BDNF and NT-3 are abundantly expressed during lizard visual system ontogeny and regeneration suggesting their participation in the development, maintenance and plasticity of the system.