bluuebunny/crossref_metadata_2025 huggingface dataset:
The Origin of the Differences in (R)‐ and (S)‐Desmethyldesferrithiocin: Iron‐Clearing Propertiesa
Authors: BERGERON RAYMOND J. , WIEGAND JAN , RATLIFF‐THOMPSON KATIE , WEIMAR WILLIAM R.
Published: February 2006

Abstract: The iron clearance properties, toxicity, and pharmacokinetics of (R)‐ and (S)‐desmethyldesferrithiocin (DMDFT) are described. The studies were performed in rodent and primate models. While both enantiomers were found to be effective iron chelators with minimal toxicity in the rodents, only (S)‐DMDFT was able to induce the clearance of any iron in the primates. In addition, two out of nine of the monkeys given (R)‐DMDFT died within 24 h of drug administration. The reason for the differences in iron clearance properties and the apparent toxicity of the (R)‐enantiomer in the primates is likely related to the disparities in the pharmacokinetics of the two analogues. The pharmacokinetic data suggest enantioselectivity in renal clearance of the desferrithiocins and their iron complexes with (S)‐DMDFT clearance 3.5 times greater than that of (R)‐DMDFT, and FeIII [(S)‐DMDFT]2 clearance 6.8 times greater than that of FeIII [R‐DMDFT]2. In all primates studied FeIII [(R)‐DMDFT]2 in the plasma exceeded 25 mg/L (50 μM) for several hours and remained above 10 mg/L (20 μM) at 8 h while levels of FeIII [(S)‐DMDFT]2 never exceeded 50 μM and were at or below the limits of detection 8 h post‐injection.
A Multi‐Center Safety Trial of the Oral Iron Chelator Deferiprone
Authors: COHEN ALAN , GALANELLO RENZO , PIGA ANTONIO , VULLO CALOGERO , TRICTA FERNANDO
Published: February 2006

Abstract: Deferiprone, also known as L1, is an orally active iron chelator that has been studied extensively in clinical trials. The sporadic occurrence of agranulocytosis in association with deferiprone and the highly variable frequency of other possible side effects such as arthralgia have created uncertainty about the true incidence of deferiprone‐related complications. A multi‐center, 1‐year trial was initiated to determine the safety profile of deferiprone. Using the Apotex formulation of deferiprone, 187 patients with thalassemia who were unable or unwilling to use deferoxamine were enrolled in four centers; 162 patients completed one year of therapy. Agranulocytosis (ANC < 500/mm3) occurred in one patient after 15 weeks of treatment, was not accompanied by infection and resolved following treatment with G‐CSF. Nine other subjects developed less severe neutropenia (ANC 500‐1500/mm3) with the lowest absolute neutrophil count reaching 500‐1250/mm3. The neutropenia in these patients developed after 1‐50 weeks of therapy, frequently accompanied febrile illnesses, and occurred predominantly in non‐splenectomized patients. Reasons other than neutropenia for discontinuing use of deferiprone included nausea (4), voluntary withdrawal (3), high ALT (2), platelet count <100,000/mm3 (2), low but unconfirmed ANC (1), protocol violation (1) fatigue (1), and depression (1). Mean ALT levels rose within three months of therapy and stabilized thereafter. Arthralgia and nausea and/or vomiting occurred in 6% and 24% of subjects, respectively. In this multi‐center trial with weekly monitoring of blood counts, the incidence of agranulocytosis was 0.58 per 100 patient‐years, and the frequency of agranulocytosis after one year was 0.5%. These findings support the safety of this formulation of deferiprone, using the careful monitoring system employed in this trial.
Global Epidemiology of Hemoglobin Disorders
Authors: ANGASTINIOTIS MICHAEL , MODELL BERNADETTE
Published: February 2006

Abstract: Thalassemias and the hemoglobinopathies such as Hemoglobins S, C and E, are now a global problem. They have spread through migration from their native areas in the Mediterranean, Africa and Asia and are now endemic throughout Europe, the Americas and Australia. Comprehensive control programs in recent years have succeeded in limiting the numbers of new births and prolonging life in affected individuals. Such programs have been successful in a minority of countries and have little global impact. Over 300,000 infants with major syndromes are born every year and the majority die undiagnosed, untreated or under‐treated.

Countries may be divided into three general categories according to the services available: A. Endemic Mediterranean countries. In these long‐established prevention programs have succeeded in achieving 80%‐100% prevention. Specialized clinics able to provide optimum treatment. B. Areas of the developed, industrialized world where prevalence is increasing because of migration. These countries have the means to provide adequate control but have problems in reaching immigrant groups with different cultural background. C. Countries of the developing world where the provision of services is hampered by economic difficulties, other health priorities due to high infant mortality from infectious diseases, and religious/cultural constraints.
Current and Future Preparative Regimens for Bone Marrow Transplantation in Thalassemiaa
Authors: STORB RAINER , YU CONG , DEEG H. JOACHIM , GEORGES GEORGE , KIEM HANS‐PETER , MCSWEENEY PETER A. , NASH RICHARD A. , SANDMAIER BRENDA M. , SULLIVAN KEITH M. , WAGNER JOHN L. , WALTERS MARK C.
Published: February 2006

Abstract: Preparative regimens for marrow allografts in thalassemia have two objectives. One is eradication of diseased marrow and the other suppression of host‐versus‐graft (HVG) reactions so that the allograft survives. A common regimen to accomplish these goals has combined high‐dose busulfan with cyclophosphamide. Postgrafting immunosuppression with cyclosporine/methotrexate has been used for GVHD prevention. Some patients may die from regimen‐related toxicity. Overall event‐free survival is 75%. Occasional patients have become mixed donor/host hematopoietic chimeras and, yet, disease symptoms have abated. This has raised the possibility of developing safer and less toxic transplant programs that result in stable mixed hematopoietic chimerism. We have devised such a program in dogs consisting of a nonlethal dose of total body irradiation (200 cGy) before and a novel combination of mycophenolate mofetil and cyclosporine after transplant. Mixed donor/host chimerism (≥ 50% donor cells in all lineages) has persisted for > 80 weeks, even though immunosuppression was discontinued after five weeks.
Treatment of Iron Overload in the “Ex‐Thalassemic”: Report from the Phlebotomy Programa
Authors: ANGELUCCI EMANUELE , MURETTO PIETRO , LUCARELLI GUIDO , RIPALTI MARTA , BARONCIANI DONATELLA , ERER BUKET , GALIMBERTI MARIA , ANNIBALI MAURO , GIARDINI CLAUDIO , GAZIEV DJAVID , RAPA SIMONA , POLCHI PAOLA
Published: February 2006

Abstract: After successful marrow transplantation (BMT) iron overload remains an important cause of morbidity in Thalassemia. After BMT, patients have normal erythropoiesis capable of producing a hyperplastic response to phlebotomy so that this procedure can be contemplated as a method of mobilizing iron from overloaded tissues. Forty‐one patients (mean age 16±2.9 years) with prolonged follow‐up (range 2‐7 years) after BMT were submitted to a moderate intensity phlebotomy program (6 ml/kg blood withdrawal at 14‐day intervals) to reduce iron overload. Values are expressed as mean ± SD or as median with a range (25th‐75th percentile). Serum ferritin decreased from 2,587 (2,129‐4,817) to 280 (132‐920) μg/l (p < 0.0001), total transferrin increased from 2.34±0.37 to 2.9±0.66 g/l (p= 0.0001), transferrin saturation decreased from 90%±14% to 39%±34% (p < 0.0001). Liver iron concentration evaluated on liver biopsy specimens decreased from 20.8 (15.5‐28.1) to 3 (0.9‐14.6) mg/g dry weight (p < 0.0001). Alanine amino‐transaminase from 5.2±3.4 to 1.6±1.2 (p < 0.0001) times the upper level of normality. The histological grading for chronic hepatitis (Histology Activity Index) decreased from 4.2±2.4 to 2.3±1.8 (p < 0.0001). Phlebotomy is a safe, efficient, and widely applicable method to decrease iron overload in “ex‐thalassemic.”
In Utero Transplantation for Thalassemia
Authors: FLAKE ALAN W. , ZANJANI ESMAIL D.
Published: February 2006

Abstract: In utero hematopoietic stem cell transplantation is a promising approach for the treatment of a variety of congenital hematologic diseases. Although the approach has been successful for immunodeficiency syndromes, attempts thus far to treat the hemoglobinopathies have failed. In most of these cases the late gestational age at transplantation, source of donor cells, or procedure‐related complications, provide an explanation for failure. Nevertheless the biology of thalassemia, in the context of prenatal transplantation, requires examination. In contrast to postnatal bone marrow transplant regimens, engraftment after in utero transplantation requires donor cells to effectively compete for developing receptive sites in the recipient hematopoietic microenvironment. Effective prenatal treatment of thalassemia will depend on the ability of normal cells to engraft and compete in the thalassemic microenvironment. Clinical observations after bone marrow transplantation of amelioration of anemia in β‐thalassemia by relatively low degrees of mixed chimerism, and the apparent selective advantage observed for donor erythropoiesis, suggest prenatal transplantation could succeed. Prenatal strategies involving multiple transplants, donor‐specific tolerance induction, and postnatal same‐donor transplants should be considered.
Unrelated and HLA‐Nonidentical Related Donor Marrow Transplantation forThalassemia and Leukemia: A Combined Report from the Seattle Marrow Transplant Team and the International Bone Marrow Transplant Registrya
Authors: SULLIVAN K. M. , ANASETTI C. , HOROWITZ M. , ROWLINGS P. A. , PETERSDORF E. W. , MARTIN P. J. , CLIFT R. A. , WALTERS M. C. , GOOLEY T. , SIERRA J. , ANDERSON J. E. , BJERKE J. , SIADAK M. , FLOWERS M. E. D. , NASH R. A. , SANDERS J. E. , APPELBAUM F. R. , STORB R. , HANSEN J. A.
Published: February 2006

Abstract: Allogeneic marrow transplantation is curative therapy for thalassemia, but fewer than 30% of patients have an HLA‐identical sibling marrow donor. Selection of alternative donors of hematopoietic stem cells (unrelated individuals or HLA‐nonidentical family members) has been aided by establishment of world‐wide donor registries now exceeding 3.6 million volunteers and by DNA‐based HLA typing to more closely match potential donors. Coupled with improved methods to control graft‐versus‐host disease and prevent fungal and cytomegalovirus infection, remarkable progress has been made in alternative donor transplantation. For patients 50 years of age or younger, with recently diagnosed chronic myelogenous leukemia (CML) in chronic phase, 1‐ and 5‐year survivals after HLA‐A, B, DRB1 identical unrelated marrow transplantation in Seattle are 82% and 74%, respectively. These results are essentially identical to outcome in similar patients given HLA‐matched sibling allografts. However, the world‐wide number of alternative donor transplants for thalassemia remains limited to date: 4 unrelated and 60 HLA‐nonidentical related transplants have been reported to the IBMTR since 1969 with actuarial overall survival of 75%. Using the paradigm of CML, it is likely that access to curative therapy of thalassemia will improve with optimal HLA typing and donor selection early in the course of disease.
The Hemoglobin E Syndromes
Authors: REES D. C. , STYLES L. , VICHINSKY E. P. , CLEGG J. B. , WEATHERALL D. J.
Published: February 2006

Abstract: Heterozygotes and homozygotes for HbE (β26, GAG‐AAG, Glu‐Lys) are microcytic, minimally anemic, and asymptomatic. The microcytosis is attributed to the β thalassemic nature of the βE gene, whereas the in vitro instability of HbE does not contribute to the phenotype. However, the compound heterozygote state HbE/β thalassemia results in a variable, and often severe anemia, with the phenotype ranging from transfusion dependence to a complete lack of symptoms. This has been well documented in Thailand, but the basis of the interaction and the cause of the variability remains unexplained. We have studied 50 HbE/β thalassemics from the UK and 16 from Oakland, CA and assessed the role of HbE instability. Time‐course globin chain synthesis experiments have shown that instability is not an important factor in the steady state, but that at 41°C newly synthesized Hb molecules are unstable. We have identified one family in which HbE interacts with pyrimidine 5′ nucleotidase deficiency to cause severe anemia with Hb instability. The UK individuals, mostly of Bengali origin, have Hb's from 4.5‐11 g/dl. The β thalassemia mutation, α thalassemia and the Xmn 1 Gγ polymorphism do not explain this variability, but the relative and absolute amounts of HbF correlate significantly with total Hb. The Oakland individuals, mostly from Southeast Asia, show similar variation in Hb, which again is largely unexplained.
The Psychosocial Impact of Chronic Illness
Authors: POLITIS CONSTANTINA
Published: February 2006

Abstract: Depending on the severity of thalassemia and the level of health care provided, the thalassemic person may suffer from his/her chronic condition going through the path: disease → impairment → disability → handicap. There is evidence that a high clinical burden is associated with a psychosocial burden for the patients and the family.

In Greece, support strategies have developed in the last twenty years to help the thalassemic patient and his/her family. Recent studies in 909 patients show that the life span is prolonged (mean age 27 years), 83% of the patients study or work, 12% are married and 2.3% have set up a family, and 98% utilize the social benefits provided (free education, free entrance to universities, tax allowances, cash benefit, early retirement, etc.). However, psychometric tests performed in 131 patients and 65 matched normal controls over 14 years of age have shown that hostility (extroverted, delusional, total p < 0.001) is an important component of the psychological profile of the patients.

The patient's role through their association is strong and undoubtedly has influenced the public's extremely high (93%) awareness of the basic features of the disease and the supportive attitude of the average Greek citizen toward the life style of the thalassemic patient. On the whole, in many thalassemic patients illness has overpowered all other aspects of life. For few, however, life is much more than an illness. Shouldn't this be the message for the patient's psychosocial support strategies?
Psychosocial Integration of Adolescents and Young Adults with Thalassemia Major
Authors: DI PALMA A. , VULLO C. , ZANI B. , FACCHINI A.
Published: February 2006

Abstract: The aim of this study was to explore the effect of thalassemia major on the psychosocial adjustment of adolescents and young adults. Design: unmarried adolescent and young adult patients were asked to fill in an ad hoc questionnaire; a semistructured interview exploring marriage and family life was done with married patients. Sample: group A: 90 unmarried patients, 50% females and 50% males, aged 14‐22 years. The control group was formed by 100 matched subjects; group B: 19 thalassemic married subjects, 6 males and 13 females, aged 28‐45 years, 7 patients had children and 12 did not. Results: group A: subjects with thalassemia had normal psychological and social development and scored better than their normal peers in tests investigating social adjustment, self‐esteem and self‐description. Moreover the family relationships of adolescents with thalassemia appeared to be stronger than those reported by normal controls; group B: the behavior of thalassemic couples did not differ from the one observed in non‐thalassemic couples in the course of previous investigations. Conclusions: Our data shows that neither thalassemic adolescents nor thalassemic married, well‐treated, young adults differ significantly from the healthy young people in their ability to cope with life's difficulties both in adolescence and marital life.
The Role of Innervation in Induction and Differentiation of Taste Organs: Introduction and Background
Authors: MISTRETTA CHARLOTTE M.
Published: February 2006

ABSTRACT: To establish lingual receptive fields that are the basic unit of taste function, ganglion cells must extend neurites to peripheral and central targets and form connections. This symposium concerns developmental interactions between the geniculate, trigeminal and petrosal ganglia and peripheral taste organs, the gustatory papillae and resident taste buds. Investigators present data from organ and tissue culture, from mice with targeted gene deletions and from grafting experiments, in pursuit of principles that direct early innervation of the taste system. The lingual ganglia and the taste papillae initially develop independently, but then become reciprocally dependent as ganglia derive neurotrophin support from gustatory papillae and the papillae require sensory innervation for growth and morphogenesis. The issue of subsequent taste bud induction is discussed with results from amphibian and mammalian models, yielding conclusions that are not yet totally convergent. However, an essential role for sensory innervation in mammalian taste bud differentiation and acquisition of appropriate quantitative relations between ganglion cells and target organs is clearly demonstrated. A working outline is presented for periods of ganglion cell/target organ independence and interdependence during early innervation of the peripheral taste system.
Nerve Dependency of Developing and Mature Sensory Receptor Cellsa
Authors: FRITZSCH BERND , BARBACID MARIANO , SILOS‐SANTIAGO INMACULADA
Published: February 2006

ABSTRACT: Old and recent data concerning development of sensory cells and trophic interdependency of sensory neurons and sensory cells is reviewed for the ear, the lateral line system, the electroreceptive system, and the taste system. All sensory neurons originate from placodes. However, only most ear, lateral line and electrosensory cells derive from placodes, while the taste sensory cell originate locally. All sensory cells apparently are nerve independent for their formation, and at least sensory cells in the ear and the taste system share the neurotrophic support for their specific sensory neurons. Later, most of these sensory cells appear to depend, to a variable degree, on some innervation for maintenance. While the molecular nature of the signal cascade from sensory cells to sensory neurons is known in at least two systems, nothing is known about the molecular nature of the signal cascade from the sensory neurons back to the sensory cells.
Taste Neurons Have Multiple Inductive Roles in Mammalian Gustatory Developmenta
Authors: OAKLEY BRUCE
Published: February 2006

ABSTRACT: The embryonic loss of brain‐derived neurotropic factor (BDNF)‐dependent taste axons in bdnf null mutant mice secondarily impairs the development of gustatory epithelia and taste buds. In normal mice gustatory development continues for at least two weeks postnatally as axons promote taste bud formation. We conclude that taste axons in the fungiform, foliate, vallate and nasopalate papillae: i) promote papilla development, and ii) establish competent gustatory cells and iii) mature taste buds. Hence, gustatory innervation contributes critically to at least three of the multiple inductive interactions controlling the development of mammalian gustatory structures.
Molecular Development of the Olfactory Nerve Pathway
Authors: KEY BRIAN
Published: February 2006

ABSTRACT: There are, at least, two major questions concerning the molecular development of the olfactory nerve pathway. First, what are the molecular cues responsible for guiding axons from the nasal cavity to the olfactory bulb? Second, what is the molecular basis of axon targeting to specific glomeruli once axons reach the olfactory bulb? Studies in the primary olfactory pathway have focused on the role of the extracellular matrix and ensheathing cells in establishing an initial substrate for growth of pioneer axons between the periphery and brain. The primary axons also express a multitude of cell adhesion molecules that regulate fasciculation of axons and hence may play a role in fascicle formation in the olfactory nerve. Although the olfactory neuroepithelium principally consists of a morphologically homogeneous class of primary olfactory neurons, there are numerous subpopulations of olfactory neurons expressing chemically distinct phenotypes. In particular, numerous subpopulations have been characterized by expression of unique carbohydrate residues and olfactory receptor proteins. Some of these molecules have recently been implicated in axon guidance and targeting to specific glomeruli.
Olfactory Development in Invertebrates On the Scent of Central Developmental Issues
Authors: TOLBERT LESLIE P.
Published: February 2006

ABSTRACT: Invertebrate olfactory systems offer many advantages for cellular and molecular studies of development and for functional studies of developmental plasticity. For example, nematodes have chemical senses that can be studied using genetic approaches. Arthropods, which include insects and crustacea, have the advantages that certain neurons can be reliably identified from one individual to another, and that olfactory receptor neurons are located on peripheral appendages and thus can be manipulated independently of their brain targets, even very early in development. Among the insects, olfactory learning can be displayed and used as a basis for studying olfactory plasticity in bees; genes are especially tractable in flies; individual growth cones can be visualized in the grasshopper embryo; and receptor neurons and glomeruli of known olfactory specificity and behavioral significance can be followed during early development in moths. In addition, many insect nervous systems are amenable to organ culture and dissociated‐cell culture, opening the door to experimental studies of cellular interactions that can not be performed in situ. Recent research in the moth Manduca sexta attempts to identify the nature of the interactions between olfactory sensory axons, olfactory neurons of the brain, and glial cells in the creation of the array of glomeruli that underlie olfaction in the adult. Results indicate that timing of the ingrowth of olfactory receptor axons is critical for normal glomerulus development, that a subset of axons expresses a fasciclin II‐like molecule that may play a role in guidance of their growth, and that glial cells must surround developing glomeruli in order to stabilize the 'protoglomerular' template made by receptor axon terminals. Moreover, glial cells are dye‐coupled to each other early in glomerulus development and gradually become uncoupled. Electrical activity in neurons is not necessary for glomerulus formation; and some intercellular interactions, perhaps involving soluble factors, appear to involve tyrosine phosphorylation. In sum, a detailed picture is emerging of the cellular interactions that lead to the formation of glomeruli.
Induced Peripheral Sensitivity in the Developing Vertebrate Olfactory System
Authors: HUDSON ROBYN , DISTEL HANS
Published: February 2006

ABSTRACT: The high dimensionality and unpredictability of the chemical world makes it difficult for the olfactory system to anticipate relevant stimuli and construct neural filters accordingly. A developmental solution to this problem would be to alter the sensory surface according to environmental conditions so as to enhance sensitivity to molecules of particular relevance. Evidence for this has been obtained in the rabbit. By feeding pregnant does aromatic juniper berries, it could be shown that newborn, weanling and even adult animals demonstrate a preference for juniper odor without subsequent postnatal experience, and that this is associated with enhanced peripheral sensitivity for juniper odor as measured by electro‐olfactogram (EOG). This is consistent with the report that in young salmon olfactory imprinting is associated with enhanced, odor‐specific sensitivity of receptor cells as measured by patch clamp. The mechanisms underlying such changes are unknown, including the extent to which they are a particular feature of developing systems.
Occurrence of ENaC Subunit mRNA and Immunocytochemistry of the Channel Subunits in Taste Buds of the Rat Vallate Papillaa
Authors: LINDEMANN B. , BARBRY P. , KRETZ O. , BOCK R.
Published: February 2006

ABSTRACT: Epithelial Na+ channels (ENaCs) are thought to mediate the amiloride‐blockable salt taste. The rat vallate papilla does not contribute to amiloride‐blockable salt taste, yet the presence of ENaC‐mRNA in this tissue has been reported. Is ENaC actually contained in the taste cells, or is it merely present in the supporting lingual epithelium? To avoid contamination by ENaC contained in the lingual epithelium, we physically isolated taste buds from the vallate papilla and used mRNA purification followed by reverse transcriptase polymerase chain reaction (RT‐PCR) to investigate the presence of ENaC‐type message in the isolated buds. mRNA of α‐, β‐ and γ‐subunits was detected, the α‐signal being the strongest. These results provide first molecular evidence for the presence of ENaC subunits in taste buds that were isolated from the posterior tongue and were free of epithelial contamination. In addition, we used immunohistochemistry to show ENaC‐like reactivity in posterior tongue taste cells. Interestingly, the immunoreactivity was not predominantly apical but was intracellular and close to or at the basolateral membrane. The function of basolateral ENaC‐type channels is unknown. Possibly, the channels are normally closed or of very low open probability in the resting state.
Salty and Sour Transduction: Multiple Mechanisms and Strain Differencesa
Authors: MIYAMOTO TAKENORI , FUJIYAMA RIE , OKADA YUKIO , SATO TOSHIHIDE
Published: February 2006

ABSTRACT: The amiloride‐sensitive and ‐insensitive components of salt‐ and acid‐induced responses in C57BL/6 and BALB/c mouse nondissociated taste cells were examined using the whole‐cell clamp technique and localized taste stimulation method. Both amiloride‐sensitive and ‐insensitive components were involved in a salt‐induced depolarizing response. The taste cells of both mouse strains exhibited an amiloride‐insensitive salt‐induced response, which consisted of multiple components. In C57BL/6 mice, an amiloride‐sensitive strain, more than 60% of salt‐induced responses were amiloride‐sensitive at the apical membrane, whereas in BALB/c mice, an amiloride‐insensitive strain, less than 40% of responses were amiloride‐sensitive. All the acid‐induced responses in taste cells examined were insensitive to amiloride, and were markedly suppressed by the Cl channel blocker, 5‐nitro‐2‐(3‐phenylpropylamino)‐benzoic acid (NPPB). These results suggest that multiple, different transduction mechanisms are involved in, and contribute to salty and sour transductions. In addition, we found that strain differences exist in salty transduction.
New Aspects of Chemoreception in Flies
Authors: HANSEN KAI , WACHT SUSANNE , SEEBAUER HELGA , SCHNUCH MARIANNE
Published: February 2006

ABSTRACT: For studies of insect taste the sensory cells of labellar taste hairs on the proboscis of calliphorid flies (e.g., Phormia) are preferred objects. Three sensory cells are electrophysiologically characterized: a sugar cell, a water cell and a cation or salt cell. Studying hairs on legs and proboscis of other families of flies we recently obtained results that extend our knowledge about the complexity of food detection in flies.

The hoverfly Eristalis tenax (Syrphidae family) feeds on nectar and pollen of flowers. While nectar is recognized via the sugar cell, the so‐called salt cell is activated by low concentrations of a water‐soluble substance in extracts of pollen. From several tested pollen constituents only proline, an essential amino acid for pollen germination, stimulates the salt cell. The discrimination between salt and pollen in behavioral tests can be explained by the finding that the water cell remains active in the presence of pollen extract, but is inhibited by salts. Obviously the water cell activity is involved in the feeding decision. We already described a similar situation in Phormia, where the salt cell activity only elicits feeding behavior when the water cell is active too.

In contrast to the sugar cells of species of flies studied so far the sugar cell of the house fly Musca domestica (Muscidae family) is highly sensitive to lactose, a disaccharide (β‐galactoside (1→4) glucoside) naturally occurring only in the milk of mammals. Thus sugar spectra adapt to special environmental food situations.

The fifth tarsomere of the forelegs of Musca bears besides two D‐hairs 46 hairs of the B‐type. The B‐hairs are functionally not uniform in contrast to their structural identity. Only two hairs, the 'water hairs,' contain a water cell beside a spontaneously firing cell, but no sugar cell. Other examples of diversity are hairs that contain apart from the classical sugar cells, additional cells which react either to p‐nitrophenyl‐β‐galactoside, but not to the chemically related lactose, or to p‐nitrophenyl‐α‐glucoside. Therefore the rule established for the labellar taste hairs that each hair type contains the same physiological equipment of sensory cells, does not hold for the taste hairs of the legs.
Noise Analysis of the Quinine‐Induced Current in Frog Taste Receptor Cellsa
Authors: TSUNENARI TAKASHI , KANEKO AKIMICHI
Published: February 2006

ABSTRACT: It has been shown that quinine, a bitter tasting substance, induces a cationic membrane current in frog taste receptor cells. We analyzed the quinine‐induced current fluctuation to further characterize the cationic channel conducting the current. Taste cells were enzymatically isolated from fungiform papillae of the bullfrog tongue. Membrane currents were recorded under voltage‐clamp by using the whole‐cell patch clamp technique. A Cs+‐containing pipette solution was used to block K+ currents. When quinine was bath applied, it induced a steady inward current in cells held at ‐60 mV. The current data were digitized at a sampling frequency of 2 kHz after having been low‐pass filtered (cut‐off frequency, 1 kHz). The spectral density distribution was calculated by 1024 points fast Fourier transform (FFT), and was fitted by a sum of two Lorentzian functions, with corner frequencies at 10‐20 Hz and at 90‐120 Hz. The single‐channel conduc tance calculated from the variance versus mean current plot was 5 pS in a normal saline solution containing 1.8 mM Ca2+. In a nominally Ca2+‐free solution, the single‐channel current was doubled. Our pre vious study has shown that the quinine‐induced current is enhanced in low extracellular [Ca2+]. This enhancement could be partly attributable to the Ca2+ suppression of the single‐channel conductance.
Molecular Cloning and Taste Bud‐Specific Expression of a Novel Cyclic Nucleotide‐Gated Channel
Authors: MISAKA TAKUMI , KUSAKABE YUKO , EMORI YASUFUMI , ARAI SOICHI , ABEA KEIKO
Published: February 2006

ABSTRACT: Cyclic nucleotide‐gated (CNG) channels serve as downstream targets of signaling pathways in vertebrate photoreceptor cells and olfactory sensory neurons. For taste signaling as well, a great deal of information is available predicting the presence of a CNG channel, but no report has been presented on its molecular entity. Here we report on molecular cloning and functional expression of a taste bud‐specific CNG channel tentatively named CNGgust.

Reverse transcriptase polymerase chain reaction (RT‐PCR) primers were synthesized according to some amino acid sequences generally conserved in many CNG channels. RT‐PCR was conducted using rat circumvallate papillary mRNA‐derived cDNA as a template to obtain positive clones. A corresponding genomic DNA clone was then obtained by screening from a genomic DNA library. Dissecting the entire structure of this gene, we found that the encoding protein had an amino acid sequence similarity of 80% to each of retina and olfactory CNG channels. It was also found by immunostaining with a specific antibody that this gustatory CNG channel (CNGgust) is localized in the tongue and also expressed specifically on the pore side of each taste bud in the circumvallate papillae. Electrophysiological experiments demonstrated that CNGgust resided in a functional state.

All these data suggest that CNGgust may be involved in taste signal transduction in sensory cells.
Behavioral and Single Chorda Tympani Taste Fiber Responses in the Common Marmoset,: Callithrix jacchus jacchus
Authors: DANILOVA VICKTORIA , HELLEKANT GÖRAN , ROBERTS THOMAS , TINTI JEAN‐MARIE , NOFRE CLAUDE
Published: February 2006

ABSTRACT: Gustatory responses of the common marmoset were studied using single fiber recordings from chorda tympani (CT) nerve and two bottle preference (TBP) tests. Hierarchical cluster analysis of 43 fibers' response profiles revealed 3 major clusters of fibers characterized by predominant sensitivity to sweeteners (S cluster), bitter compounds (Q cluster) or acids (H cluster). NaCl as well as LiCl did not stimulate CT taste fibers. The TBP tests showed relationship between a compound's ability to stimulate the taste fibers and the animals' consumption. Activity in the S cluster was associated with preference, while the activity in the Q cluster was associated with rejection. Marmosets neither preferred nor rejected sweeteners which did not stimulate any CT fibers.
Dietary Fat Preferences Are Inversely Correlated with Peripheral Gustatory Fatty Acid Sensitivitya
Authors: GILBERTSON TIMOTHY A. , LIU LIDONG , YORK DAVID A. , BRAY GEORGE A.
Published: February 2006

ABSTRACT: We previously demonstrated that taste receptor cells (TRCs) respond to cis‐polyunsaturated fatty acids (PUFAs) through an inhibition of delayed rectifying K channels (KDR),1 which may represent the transduction mechanism for dietary fat. To determine if there is a link between the sensitivity of fungiform TRCs to PUFAs and dietary fat preferences, we compared the PUFA‐sensitivity of TRCs using patch clamp techniques from Osborne‐Mendel (O‐M) and S5B/Pl rats, which display dietary preferences for fat over carbohydrate and carbohydrate over fat, respectively.3 In isolated TRCs, the PUFAs, linoleic (C18:2), linolenic (C18:3) and arachidonic acid (C20:4) inhibit KDR in a concentration‐dependent manner in both strains, while the unsaturated lauric acid (C12:0) was ineffective. KDR from TRCs of S5B/Pl rats were significantly more sensitive to inhibition by all three PUFAs (10 μM) than were TRCs from O‐M rats. We are currently investigating whether this differential responsiveness is due to (i) the relative affinity of the interaction between cis‐PUFAs and the delayed rectifying K channels or (ii) the relative density of delayed rectifying K channels in the two rat strains. Whatever the mechanism, these data suggest an inverse correlation between peripheral gustatory sensitivity to PUFAs and the dietary preference for fat. This finding may provide insight into the mechanism for sensing dietary fat that allows the S5B rats to reduce fat intake on a high‐fat diet and avoid the obesity which results when O‐M rats eat a high‐fat diet.
Identification and Characterization of Human Fructose or Glucose Taste Variants with Hypogeusia for One Monosaccharide but Not for the Othera
Authors: EYLAMB SHACHAR , KENNEDY LINDA M.
Published: February 2006

ABSTRACT: Human psychophysical functions for sweetness are similar for sucrose and fructose, but different for glucose, and suggest different mechanisms for fructose and glucose. Drosophila behavioral and electrophysiological data are similar to the human data and indicate separate receptor cell mechanisms for the monosaccharides. Moreover, fructose 'nontasters' (NTs) and glucose NTs have been identified in two Drosophila species. Identification of human NTs would confirm separate mechanisms and could lead to identification of proteins in human sweet taste by molecular genetic techniques. To identify human NTs, we first obtained responses for sucrose, fructose and glucose from 20 subjects. They tasted seven concentrations of each sugar (2‐128 mM), paired with water, and indicated the sweeter of each pair. Functions for recognition indices (RIs) (proportion of subjects recognizing the sugar as sweeter) were similar for sucrose and fructose and different for glucose; this result agrees with the previous studies and supports different mechanisms for the monosaccharides. At 128 mM, RIs for all three sugars were 1.0; this result is consistent with the monogeusia reported by Breslin et al.4 for concentrations higher than those tested here. Eleven rising‐phase concentrations (10‐35 mM fructose, 10‐90 mM glucose) then were tested on 32 subjects. A statistically significant interaction indicated different regression slopes and supported different monosaccharide mechanisms. From these data, positive identification values (PIDs) (lowest concentration at which the sugar always was judged sweeter than the water) were determined for each subject. The fructose log(PID) and glucose log(PID) data were not well correlated; thus separate mechanisms were supported further. Next, NT traits were defined by log(PID)s ≥ 2 SD above the mean for one sugar, while the PID for the other remained within 1 SD of the population mean log(PID). Ninety‐two subjects were screened to identify 12 glucose NTs and four fructose NTs. Two glucose NTs and three average subjects were tested in six additional sessions. The NTs showed an experience‐induced change: there was a statistically significant reduction of glucose PIDs, but not of fructose PIDs. No change occurred in PIDs of the average subjects for either sugar.
Expression and Functional Analysis of Olfactory Receptorsa
Authors: Breer H. , Krieger J. , Meinken C. , Kiefer H. , Strotmann J.
Published: February 2006

ABSTRACT: The olfactory system recognizes and discriminates myriads of odorants of diverse molecular structure. This task is supposed to be accomplished by a large array of seven‐transmembrane domain receptors encoded by a multigene family. Although circumstantial evidence suggests that the identified genes encode odorant receptors, unequivocal proof requires demonstration that the resulting proteins should be able to interact with odorous molecules and couple via G proteins onto second messenger cascades. This goal can be achieved by heterologous expression of receptor proteins in surrogate eucaryotic cells, although the task is complicated by the diversity of putative odorous ligands and the large size of the receptor family. Employing the baculovirus/Sf9 cell system it was found that receptor proteins can be expressed at high levels. Stimulating receptor‐expressing Sf9 cells with a mixture of numerous odorous compounds elicited a significant and dose‐dependent second messenger response, which was never observed in control cells. Assaying a large panel of odorous compounds, including representatives of different odor classes and compounds of different chemical classes revealed that distinct receptor subtypes respond to certain odorants but not to others. Graded responses to only a subset of odorants indicate that the heterologous expressed receptor types have a selective but relatively broad ligand specificity. The easily manipulated bacterial system was employed to produce olfactory receptor proteins in large quantities. It was solubilized from inclusion bodies and upon reconstitution in liposomes displayed specific interaction with odor ligands.
Organizational Complexity in Lobster Olfactory Receptor Cellsa
Authors: ACHE BARRY W. , MUNGER STEVEN , ZHAINAZAROV ASLBEK
Published: February 2006

ABSTRACT: The current working model of transduction in lobster olfactory receptor cells suggests that: (1) inositol‐1,4,5‐triphosphate (IP3) is the excitatory olfactory second messenger in these cells; (2) activation of the cell also involves a secondary, current‐carrying channel; and (3) the phosphoinositol pathway works in parallel to a second, cyclic nucleotide‐mediated signaling pathway that provides input of opposite polarity into the cell. The complexity of intracellular signaling in lobster olfactory receptor cells renders the cells capable of fine tuning, and even integrating, the signal they send to the brain.
Role of Cyclic GMP in Olfactory Transduction and Adaptationa
Authors: ZUFALL FRANK , LEINDERS‐ZUFALL TRESE
Published: February 2006

ABSTRACT: The detection of odor molecules by vertebrate olfactory receptor neurons (ORNs) involves signal transduction mechanisms that are thought to occur primarily through a cyclic adenosine monophosphate (cAMP)‐mediated second messenger pathway. There has been intense debate whether cAMP is the sole second messenger responsible for all excitation and adaptation. The recent identification of a distinct form of odor adaptation that depends on the carbon monoxide/cyclic guanosine monophosphate (cGMP) second messenger system demonstrates that cAMP alone cannot account for all phases of adaptation and that multiple second messenger pathways exist in ORNs to perform distinct but closely related olfactory functions.
Visualizing Odor Detection in Olfactory Cilia by Calcium Imaginga
Authors: LEINDERS‐ZUFALL TRESE , GREER CHARLES A. , SHEPHERD GORDON M. , ZUFALL FRANK
Published: February 2006

ABSTRACT: To visualize odor detection in individual cilia of olfactory sensory neurons we have developed a new approach by using high‐resolution calcium imaging techniques. Laser scanning confocal microscopy revealed, for the first time, that odor stimuli induce transient Ca2+ elevations in single olfactory cilia. Pharmacological analysis indicates that these Ca2+ signals depend entirely on Ca2+ entry through activated cyclic nucleotide‐gated (CNG) channels. This novel approach enables us to monitor the initial steps leading to olfactory perception in a spatially and temporally resolved manner.
An Analysis of Odorant‐Induced Currents in On‐Cell Patches on Mammalian Olfactory Receptor Neuronsa
Authors: Barry Peter H. , Chiu Pauline , Lynch Joseph W.
Published: February 2006

ABSTRACT: Because of the difficulty of obtaining odorant‐induced currents in mammalian olfactory receptor neurons using whole‐cell recording, we have developed a mathematical model of the electrical circuit of the patch and rest‐of‐cell. This can be used to quantitatively analyze on‐cell patch pipette currents in response to perfusion of the cell by solutions containing odorants or other compounds that can alter membrane conductance or cell potential. We have analyzed pipette currents from on‐cell patches of olfactory receptor neurons (ORNs) dissociated from adult rats. Initially, we perfused the ORNs with a high (100 mM; control 10 mM) KCl solution, which immediately induced a current flux from cell to pipette of a magnitude to imply a depolarization of ∼ 52 mV, close to the value predicted from the Nernst equation (56 mV), and no change in the patch conductance. In contrast, perfusion by a cocktail of five cyclic adenosine‐3',5'‐monophosphate (cAMP)‐stimulating odorants (cineole, n‐amyl acetate, methyl salicylate, limonene and α‐pinene, each at a concentration of 1 mM), after a delay of 4‐10 sec, induced a current flux from pipette into the cell. Data in normal [Ca2+] and [Mg2+] implied an average patch conductance increase of ∼ 36 pS, a cell depolarization of ∼ 13 mV and an odorant‐induced single channel conductance of ∼ 16 pS. In low [Ca2+] and no Mg2+∼ 40% of cells responded to odorants, with an induced current flow from cell to pipette implying a patch conductance increase of ∼ 115 pS and cell depolarization of ∼ 32 mV. The results were consistent with the odorants gating cAMP‐gated cation channels. This analytical approach, which enables estimates of odorant‐induced voltage and conductance changes to be made from changes in pipette current, should also be of general use for comparing cell responses to different perfusing solutions.
Involvement of Genes Encoding a K+ Channel (ether a go‐go) and a Na+ Channel (smellblind) in Drosophila Olfactiona
Authors: DUBIN ADRIENNE E. , LILES MARGARET M. , SELIGMAN FE , LE TAMMI , TOLLI JOHN , HARRIS GREG L.
Published: February 2006

ABSTRACT: We have investigated the roles of the putative cyclic nucleotide‐modulated K+ channel subunit encoded by the ether a go‐go (eag) gene and a voltage‐gated Na+ channel, smellblind (sbl), encoded by the paralytic (para) locus in odorant responsiveness and cell excitability in Drosophila melanogaster. Three independent mutant alleles of eag revealed reduced antennal responsiveness in adult flies to a subset of odorants, all having short aliphatic side chains: ethyl butyrate (EB), propionic acid, 2‐butanone and ethyl acetate (manuscript submitted). Loose patch recordings revealed that significantly fewer eag antennal neurons responded to EB compared to control neurons. As expected if Eag were involved in odor transduction, fewer EB‐induced inhibitory responses were observed in eag mutants and focal application of high K+ saline to sensillae altered the excitability of the majority of neurons from wild‐type, but not eag, antennae. Interestingly, there were fewer excitatory odorant responses dependent on extracellular Ca2+ in eag neurons. In contrast to the involvement of Eag in adult olfactory neuron odorant transduction, we found no evidence that adult sbl and allelic olfactory D (olfD) gene mutants were defective in their behavioral response to a complex attractive odor. Furthermore, electrophysiological analyses of adult sbl and olfD mutants revealed normal electroantennogram responses to a broad range of individual pure odorants and no changes in the excitable properties of olfactory neurons as determined by loose patch recordings.
Factors Regulating Neurogenesis and Programmed Cell Death in Mouse Olfactory Epitheliuma
Authors: CALOF ANNE L. , RIM PETER C. , ASKINS KAREN J. , MUMM JEFFREY S. , GORDON MELINDA K. , IANNUZZELLI PASQUALE , SHOU JIANYONG
Published: February 2006

ABSTRACT: To identify factors regulating neurogenesis and programmed cell death in mouse olfactory epithelium (OE), and to determine the mechanisms by which these factors act, we have studied mouse OE using two major experimental paradigms: tissue culture of embryonic OE and cell types isolated from it; and ablation of the olfactory bulb('bulbectomy') of adult mice, a procedure that induces programmed cell death of olfactory receptor neurons (ORNS) and a subsequent surge of neurogenesis in the OE in vivo. Such experiments have been used to characterize the cellular stages in the ORN lineage, leading to the realization that there are at least two distinct stages of proliferating neuronal progenitor cells interposed between the ORN and the stem cell that ultimately gives rise to it. The identification of a number of different factors that act to regulate proliferation and survival of ORNs and progenitor cells suggests that these multiple cell stages may each serve as a control point at which neuron number in the OE is regulated. Our recent studies of neuronal colony‐forming progenitors (putative stem cells) of the OE suggest that even these cells, at the earliest stage in the ORN lineage so far identified, are subject to such regulation: if colony‐forming progenitors are cultured in the presence of a large excess of differentiated ORNs, then the production of new neurons by progenitors is dramatically inhibited.6 This result suggests that differentiated ORNs produce a signal that feeds back to inhibit neurogenesis by their own progenitors, and provides a possible explanation for the observation that ORN death, consequent to bulbectomy, results in increased neurogenesis in the OE in vivo: death of ORNs may release neuronal progenitor cells from this inhibitory signal, produced by the differentiated ORNs that lie near them in the OE. Our current experiments are directed toward identifying the molecular basis of this inhibitory signal, and the cellular mechanism(s) by which it acts.