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At least 721 records · Page 40Linked to original sources
PubMed2002

Altered electrodermal response to facial expression after closed head injury.

UNLABELLED: The objective was to determine whether diffuse damage to orbital and ventromedial regions of the prefrontal cortex usually associated with moderate-to-severe closed head injury (CHI) would affect the ability to perceive and respond to socially relevant information. METHODS: Participants with CHI and age-matched non-injured controls were presented with faces that varied with respect to emotional expression while electrodermal activity (EDA) was monitored. Cognitive and general adaptive functioning was also assessed. RESULTS: CHI was associated with a failure to increase EDA in response to negative facial expressions and with reduced ability to identify negative expressions, especially fear. The groups differed on other signs of orbital/medial prefrontal damage such as anosmia and in general social adaptability and awareness-of-deficit as measured by the Brock Adaptive Functioning Questionnaire. CONCLUSIONS: CHI affected the ability to identify and respond to negative facial expression. Addressing these deficits may enhance rehabilitative efforts within the social domain.

Adult↗
PubMed2003

Olfactory function after mild traumatic brain injury.

OBJECTIVE: The aim of this study was to determine the incidence of olfactory dysfunction after mild traumatic brain injury (MTBI). Damage to the olfactory bulbs or frontal cortex has been reported in MTBI, but olfactory dysfunction after MTBI has not been studied in a prospective way before. DESIGN: Patients with first-time MTBI were included. Patients' olfactory threshold values (Hyposmia Utility Kit by Olfacto-Labs) were measured 2 weeks after the trauma. Associations between olfactory threshold values and individual symptoms and S-100B and NSE concentrations were examined, using multiple linear regression analysis, adjusting for the influence of age. RESULTS: Twenty-two per cent of 111 included patients had hyposmia and 4% had anosmia. Thresholds at 2 weeks showed no significant associations with the presence of symptoms at the ER, nor with early concentrations of S-100B or NSE. CONCLUSIONS: Although a high prevalence of olfactory dysfunction was found, no correlation was found between olfactory dysfunction and acute parameters of MTBI.

Adolescent↗
PubMed1985

Smell of danger: an analysis of LP-gas odorization.

LP-gas derives warning properties from the odorants ethyl mercaptan or thiophane. Laboratory tests have implied that the average person has the ability to smell the odors before leaking LP-gas reaches one-fifth its lower limit of flammability. Generally, however, laboratory tests ignore or discard persons with a poor sense of smell, especially the elderly and persons with certain types of hyposmia. Some persons who apparently can smell the warning agents when directed may otherwise fail to notice or identify them. Elderly men seem particularly vulnerable to instances of incidental anosmia and olfactory agnosia. Psychophysical testing of the warning agents has been rather unsophisticated. There exists neither a standard protocol for testing nor adequate specification of the perceptual properties that might make one warning agent better than another. Without such developments, improvement in warning agents will fail to occur. Possible improvements include increases in concentration, the use of blends to insure more uniform delivery of agent and, to decrease the perceptual vulnerability of relatively insensitive people, use of agents with favorable psychophysical (stimulus-response) functions and use of agents with favorable adaptation characteristics. Even without a change in existing products, it seems advisable to learn more about the vulnerability of LP-gas users and to employ educational means to reduce risks.

Diffusion↗
PubMed1985

Impairment of olfactory recognition after closed head injury.

To investigate the effects of closed head injury (CHI) on olfactory identification, we administered a test of olfactory naming and forced choice recognition to 52 CHI patients who had no evidence of anosmia. The Olfactory Identification Test consisted of 'scratch and sniff' labels of familiar nonirritant odorants. In comparison with a normal control group (n = 19) of similar age, olfactory naming and recognition were impaired in the CHI series, particularly in patients with moderate or severe head injury. The presence of a haematoma or contusion in the frontal/temporal region was also related to impaired olfactory recognition. We suggest that nonmissile head injury can produce at least a partial impairment of olfactory recognition despite relatively preserved olfactory detection.

Adolescent↗
PubMed1995

Superficial siderosis of the central nervous system.

There have been 87 cases of superficial siderosis of the CNS reported in the world literature and 63 cases had developed the clinical syndrome with sufficient details to be reviewed. It is a distinct clinical syndrome characterized by sensorineural deafness (95%), cerebellar ataxia (88%) and pyramidal signs (76%). Other features include dementia (24%), bladder disturbance (24%), anosmia (at least 17%), aniscoria (at least 10%) and sensory signs (13%). Less frequent features are extra-ocular motor palsies, neck or backache, bilateral sciatica and lower motor neuron signs (5-10% each). Males are more often affected than females (3:1). The age of onset ranged from 14 to 77 years, age at death from 29 to 78 years and duration until death from 1 to 38 years excluding premature death due to the underlying cause or as a result of surgery. Up to 27% become bed bound at 1-37 years from the first symptom due to either cerebellar ataxia, a myelopathic syndrome or both. Symptomatic subarachnoid haemorrhage occurred in 37% and the CSF was haemorrhagic and/or xanthochromic in 75%. It is now accepted that superficial siderosis is due to chronic subarachnoid haemorrhage and a source of bleeding has been reported in 54% of cases; it was either due to dural pathology (47%) including a CSF cavity lesion or cervical root lesion, a vascular tumour (35%) or a vascular abnormality (18%). Arguments are presented that the remaining cases were also due to chronic haemorrhage and that there is no evidence for a non-haemorrhagic form of superficial siderosis. There have been 14 incidental cases diagnosed by MRI or at post-mortem with no symptoms attributable to superficial siderosis during life, supporting the notion of a pre-symptomatic phase to the illness. In 22 patients who had developed the syndrome, the duration of this pre-symptomatic phase could be calculated and ranged from 4 months to 30 years with an average of 15 years. At present the most promising treatment for superficial siderosis is surgical ablation of the bleeding sources.

Adolescent↗
PubMed2002

Clinical correlates of selective pathology in the amygdala of patients with Parkinson's disease.

The amygdala exhibits significant pathological changes in Parkinson's disease, including atrophy and Lewy body (LB) formation. Amygdala pathology has been suggested to contribute to some clinical features of Parkinson's disease, including deficits of olfaction and facial expression. The degree of neuronal loss in amygdala subnuclei and the relationship with LB formation in non-demented Parkinson's disease cases have not been examined previously. Using stereological methods, the volume of neurones and the number of neurones in amygdala subdivisions were estimated in 18 prospectively studied, non-demented patients with Parkinson's disease and 16 age- and sex-matched controls. Careful exclusion (all cortical disease) and inclusion (non-demented, levodopa-responsive, idiopathic Parkinson's disease or controls) criteria were applied. Seven Parkinson's disease cases experienced well-formed visual hallucinations many years after disease onset, while nine Parkinson's disease cases and three controls were treated for depression. Anatomically, the amygdala was subdivided into the lateral nucleus, the basal (basolateral and basomedial) nuclei and the corticomedial (central, medial and cortical nuclei) complex. LB and Lewy neurites were identified by immunohistochemistry for alpha-synuclein and ubiquitin and were assessed semiquantitatively. LB were found throughout the amygdala in Parkinson's disease, being present in approximately 4% of neurones. Total amygdala volume was reduced by 20% in Parkinson's disease (P = 0.02) and LB concentrated in the cortical and basolateral nuclei. Lewy neurites were present in most cases but did not correlate with any structural or functional variable. Amygdala volume loss was largely due to a 30% reduction in volume (P = 0.01) and the total estimated number of neurones (P = 0.007) in the corticomedial complex. The degree of neurone loss and the proportion of LB-containing neurones in the cortical nucleus within this complex were constant across Parkinson's disease cases and neither variable was related to disease duration (R(2 )< 0.03; P > 0.5). The cortical nucleus has major olfactory connections and its degeneration is likely to contribute to the early selective anosmia common in Parkinson's disease. There was a small reduction in neuronal density in the basolateral nucleus in all Parkinson's disease cases, but no consistent volume or cell loss within this region. However, the proportion of LB-containing neurones in the basolateral nucleus was nearly doubled in cases that exhibited visual hallucinations, suggesting that neuronal dysfunction in this nucleus contributes to this late clinical feature. Detailed quantitation of the other amygdala subdivisions failed to reveal any other substantial anomalies or any associations with depression. Thus, the impact of Parkinson's disease on the amygdala is highly selective and correlates with both early and late clinical features.

Aged↗
PubMed2006

Interactions between olfaction and the trigeminal system: what can be learned from olfactory loss.

The olfactory and the trigeminal systems have a close relationship. Most odorants also stimulate the trigeminal nerve. Further, subjects with no sense of smell exhibit a decreased trigeminal sensitivity with unclear underlying mechanisms. Previous studies indicated that single stages of trigeminal processing may differently be affected by olfactory loss. A better knowledge of adaptive and compensatory changes in the trigeminal system of subjects with acquired anosmia (AA) will improve the understanding of interactive processes between the 2 sensory systems. Thus, we aimed to assess trigeminal function on different levels of processing in subjects with AA. Subjects with AA showed larger electrophysiological responses to irritants obtained from the mucosa than healthy controls. On central levels, however, they exhibited smaller event-related potentials and psychophysical measures to irritants. Over 9 months, they exhibited an increase in trigeminal sensitivity. Subjects with recovering olfactory function showed an even more increased peripheral responsiveness to irritants. These data suggest dynamic mechanisms of mixed sensory adaptation/compensation in the interaction between the olfactory and trigeminal systems, where trigeminal activation is increased on mucosal levels in subjects with AA and amplified on central levels in subjects with a functioning olfactory system.

Evoked Potentials↗
PubMed1994

Individual differences in the perceived intensity and quality of specific odors following self- and cross-adaptation.

Adaptation techniques have traditionally been employed in sensory physiology and psychology to characterize afferent pathways and to dissect the quantitative and, to a lesser degree, the qualitative aspects of perception. We continue to explore the individual differences in olfactory capabilities among subjects initially classified by their ability to detect and identify the diastereoisomeric ketone, cis-4-(4'-t-butylcyclohexyl)-4-methyl-2-pentanone (pemenone) which shares with 5 alpha-androst-16-en-3-one (androstenone) a pronounced urine-sweaty odor. Our previous studies of these and other compounds for which specific anosmias were said to exist revealed significant relationships between intensity scores and a corresponding clustering of the odor quality descriptors used to characterize these materials by subjects judged to be specifically anosmic for the urinous note. Here, we attempt to dissect the web of interactions which give rise to individual differences in perceived odor quality by evaluating the effects of self- and cross-adaptation on the intensity and quality reports elicited by pemenone, androstenone and four other odors in 18 human subjects including both pemenone-osmic and non-osmic (n = 6) individuals. Intensity and quality ratings for the six compounds were obtained before and after an adaptation sequence in which subjects sniffed a test odorant, pemenone or the diluent. For each odorant, intensity ratings under the different adapting conditions were compared by ANOVA. Self-adaptation was universal but cross-adaptation by pemenone was only found in the intensity ratings of androstenone. The intensity ratings of isovaleric acid, which shares the urinous note with pemenone and androstenone, were unaffected by pemenone adaptation. Most of the subjects judged to be osmic still reported a urinous odor quality for androstenone and isovaleric acid following pemenone adaptation. Except for shifts to the no-odor category, adaptation did not significantly alter the odor quality reports of osmic or non-osmic individuals. This suggests that the odor quality reports engendered by these substances are multidimensional and that compounds which share the same odor quality label may interact with different perceptual channels.

Adaptation, Physiological↗
PubMed1995

Variation in odor thresholds for l-carvone and cineole and correlations with suprathreshold intensity ratings.

Specific anosmias have been reported for l-carvone and cineole, two compounds of importance in food flavor perception. Detection thresholds were assessed in groups of 50+ individuals by ascending forced-choice tests conducted in quadruplicate. Wide individual differences in thresholds were observed. Within the same session, threshold correlations were in the range of +0.8 to +0.9, showing good short-term reliability. Correlations with suprathreshold ratings were moderate (in the range of r = -0.5) after subtraction of false positive ratings for blank samples. However, a cineole mixture experiment failed to show any differences between subgroups that were previously classified as high or low sensitivity on the basis of threshold measurements. Re-testing selected groups after a period of months showed considerable within-individual variation in the thresholds, especially for l-carvone. These results call into question the stability and utility of threshold classification for these two compounds.

Adult↗
PubMed2002

Cell death of olfactory receptor neurons in a rat with nasosinusitis infected artificially with Staphylococcus.

Nasosinusitis is a common cause of acquired hyposmia or anosmia. To study the apoptotic death of olfactory receptor neurons in nasosinusitis, we made an inflammation model in rat infected with Staphylococcus. The histochemical changes in olfactory epithelium were examined using antibodies against protein gene product 9.5 (PGP 9.5), single-strand DNA (ssDNA), Bcl-2 and Bax that might be involved in the apoptosis of olfactory receptor neurons. The thickness of olfactory epithelium and the number of ssDNA-labeled cells were evaluated in each post-treatment group and the results were analyzed by two-way analysis of variance (ANOVA) and post hoc tests. Hematoxylin-eosin staining showed that a severe inflammatory reaction had occurred on the infected side of the nasal cavity and sinus, but not on the non-infected side. However, apoptosis of olfactory receptor neurons occurred on both sides; the apoptosis on the non-infected side started later and behaved like a shadow curve similarly to the infected side. Repeated measures ANOVA showed significant differences of both the thickness of olfactory epithelium (P < 0.0001) and the number of ssDNA-labeled cells (P = 0.0339) in the epithelium between the infected side and non-infected side comparing treatment, time and their interactions. Bcl-2 and Bax were detected only on the infected side in the early stages. Thus, nasosinusitis induced the apoptosis of olfactory receptor neurons. However, the apoptosis occurred not only on the infected side, but also on the non-infected side with no significant inflammation. The Bcl-2/Bax family seems to play an important role in the apoptosis induced by infection, but not in the apoptosis on the non-infected side. The results suggest that mechanisms of apoptosis of olfactory receptor neurons on the infected side may differ from those on the non-infected side.

Analysis of Variance↗
PubMed2002

Distortion of olfactory perception: diagnosis and treatment.

Clinically, olfaction can fail in any of three ways: (i) decreased sensitivity (hyposmia, anosmia) and two types of distortion (dysosmia); (ii) distorted quality of an odorant stimulation (troposmia); (iii) perceived odor when no odorant is present (phantosmia, hallucination). The distortions are usually much more upsetting to a person's quality of life than a simple loss. An ipsilatersal loss of olfactory sensitivity is often identified in the nostril with any type of olfactory distortion. The pathophysiology of a stimulated distortion (troposmia) is likely a decreased number of functioning olfactory primary neurons so that an incomplete characterization of the odorant is made. In phantosmia, two possible causations include an abnormal signal or inhibition from the primary olfactory neurons or peripheral olfactory or trigeminal signals that "trigger" a central process. The clinician's goal is to carefully define the problem (e.g. taste versus smell, real versus perceived, one versus two nostrils), to perform the appropriate examination and testing and to provide therapy if possible. Treatment includes assurance with no active therapy (because many of these will naturally resolve), topical medications, systemic medications, anesthesia to parts of the nose and, rarely, referral for surgical excision of olfactory neurons. Endoscopic transnasal operations have the advantage of treating phantosmia and sometimes allowing a return of olfactory ability after the operation.

Humans↗
PubMed2005

Olfactory responsiveness to two odorous steroids in three species of nonhuman primates.

Social communication by means of odor signals is widespread among mammals. In pigs, for example, the C19-steroids 5-alpha-androst-16-en-3-one and 5-alpha-androst-16-en-3-ol are secreted by the boar and induce the mating stance in the sow. In humans, the same substances have been shown to be compounds of body odor and are presumed to affect human behavior. Using an instrumental conditioning paradigm, we here show that squirrel monkeys, spider monkeys and pigtail macaques are able to detect androstenone at concentrations in the micromolar range and thus at concentrations at least as low as those reported in pigs and humans. All three species of nonhuman primates were considerably less sensitive to androstenol, which was detected at concentrations in the millimolar range. Additional tests, using a habituation-dishabituation paradigm, showed that none of the 10 animals tested per species was anosmic to the two odorous steroids. These results suggest that androstenone and androstenol may be involved in olfactory communication in the primate species tested and that the specific anosmia to these odorants found in approximately 30% of human subjects may be due to their reduced number of functional olfactory receptor genes compared with nonhuman primates.

Androstenols↗
PubMed2006

Combined behavioral and c-Fos studies elucidate the vital role of sodium for odor detection.

Salt, known as taste quality, is generally neglected in olfaction, although the olfactory sensory neurons stretch into the salty nasal mucus covering the olfactory epithelium (OE). Using a psychophysical approach, we directly and functionally demonstrate in the awake rat for a variety of structurally diverse odorants that sodium is a critical factor for olfactory perception and sensitivity, both very important components of mammalian communication and sexual behavior. Bathing the olfactory mucus with an iso-osmotic sodium-free buffer solution results in severe deficits in odorant detection. However, sensitivity returns fully within a few hours, indicating continuous mucus production. In the presence of sodium in the mucus covering the OE, all odorants induce odorant-specific c-Fos expression in the olfactory bulb. Yet, if sodium is absent in the mucus, no c-Fos expression is induced as demonstrated for n-octanal. Our noninvasive approach to induce anosmia in mammals here presented--which is fully reversible within hours--opens new possibilities to study the functions of olfactory communication in awake animals.

Acetates↗
PubMed1996

Genotypic and phenotypic characterization of the Drosophila melanogaster olfactory mutation Indifferent.

Two Drosophila melanogaster third chromosomes carrying the EMS-induced mutations IndifferentA (IndfA) and IndifferentB (IndfB), previously isolated from larvae showing an anosmia when stimulated with nonanol, were recombined with a multi-marked chromosome in order to localize the mutant character(s). Recombinant strains were tested for their larval olfactory responses and classed as either mutant or wild type; both Indf characters were found to be located on the right arm of the chromosome, between ebony and claret. Deletion mapping suggests that the Indifferent wild-type character is a haplo-insufficiency and that IndfA and IndfB are located in cytological region 96A2-7. Deficiencies and both mutant strains were tested with 14 closely related odors (alcohols, acetates, acids and methyl esters, between eight and 10 carbons long). When stimulated with methyl octanoate, IndfA and IndfB appeared recessive; noncomplementation was observed for this phenotype in IndfA/IndfB hybrids indicating that the two characters are allelic. The overall responses of IndfA, IndfB and the deficiencies indicate that Indf is involved in processing organic odors of between eight and 10 carbons in length.

Animals↗
PubMed2001

Structure-function analysis of phytanoyl-CoA 2-hydroxylase mutations causing Refsum's disease.

Refsum's disease is a neurological syndrome characterized by adult-onset retinitis pigmentosa, anosmia, sensory neuropathy and phytanic acidaemia. Many cases are caused by mutations in peroxisomal oxygenase phytanoyl-CoA 2-hydroxylase (PAHX) which catalyses the initial alpha-oxidation step in the degradation of phytanic acid. Both pro and mature forms of recombinant PAHX were produced in Escherichia coli, highly purified, and shown to have a requirement for iron(II) as a co-factor and 2-oxoglutarate as a co-substrate. Sequence analysis in the light of crystallographic data for other members of the 2-oxoglutarate-dependent oxygenase super-family led to secondary structural predictions for PAHX, which were tested by site-directed mutagenesis. The H175A and D177A mutants did not catalyse hydroxylation of phytanoyl-CoA, consistent with their assigned role as iron(II) binding ligands. The clinically observed P29S, Q176K, G204S, N269H, R275Q and R275W mutants were assayed for both 2-oxoglutarate and phytanoyl-CoA oxidation. The P29S mutant was fully active, implying that the mutation resulted in defective targeting of the protein to peroxisomes. Mutation of Arg-275 resulted in impaired 2-oxoglutarate binding. The Q176K, G204S and N269H mutations caused partial uncoupling of 2-oxoglutarate conversion from phytanoyl-CoA oxidation. The results demonstrate that the diagnosis of Refsum's disease should not solely rely upon PAHX assays for 2-oxoglutarate or phytanoyl-CoA oxidation.

Amino Acid Sequence↗
PubMed1993

Heterogeneity in the mutations responsible for X chromosome-linked Kallmann syndrome.

Kallmann syndrome represents the association of hypogonadotropic hypogonadism with anosmia. Three modes of transmission, X chromosome-linked, autosomal recessive and autosomal dominant, have been described. The KAL gene, responsible for the X-linked form of the disease, has been isolated and its intron-exon organization recently determined. We have searched for mutations of the KAL gene in 21 unrelated males affected by familial Kallmann syndrome. In these families, segregation of the disease was suggestive of the X-linked mode of transmission. In 2 families, large Xp22.3 deletions, both including the entire KAL gene, have been detected by Southern blot analysis. Here we report the sequence analysis of the entire coding region of the KAL gene in the 19 remaining patients. The approach consisted of sequencing each of the 14 coding exons and splice site junctions. Each exon was amplified by PCR on the genomic DNA, using oligonucleotides from the flanking intronic sequences as specific primers. Nine point mutations were identified at separate locations in four exons and one splice site, providing strong evidence for heterogeneity in mutations responsible for the X-linked Kallmann syndrome. In addition, the high frequency of unilateral renal aplasia in X-linked Kallmann patients (6 out of 11 males with identified alterations of the KAL gene) should be emphasized.

Amino Acid Sequence↗
PubMed1996

The Kallmann syndrome gene product expressed in COS cells is cleaved on the cell surface to yield a diffusible component.

Kallmann syndrome is characterized by hypogonadotropic hypogonadism and anosmia and caused by a defect of migration and targeting of gonadotropin-releasing hormone-secreting neurons and olfactory axons during embryonic development. We previously cloned the gene responsible for the X-linked form of the disease encoding a 680 amino acid protein, KAL, which displays the unusual combination of a protease inhibitor domain with fibronectin type III repeats. Previous expression studies by northern blot and RNA in situ hybridization in human and chick indicated that the gene is expressed at very low levels in the olfactory bulb during development. Therefore, low abundance of the protein has hampered a detailed biochemical characterization. By overexpressing both the human and chick KAL cDNAs in eukaryotic cells, we now provide evidence that KAL is a glycosylated peripheral membrane protein with an apparent molecular weight of approximately 100 kDa. We show that this 100 kDa protein is proteolytically processed on the cell membrane to yield a 45 kDa diffusible component, which is detectable with an antisera against the C-terminal part of the protein and binds tightly to cell surfaces. These data provide a first step toward understanding KAL function in neuronal interactions and neurite extension in the olfactory bulb and suggest that KAL might be a diffusible chemoattractant molecule for olfactory axons.

Amino Acid Sequence↗
PubMed2004

The product of X-linked Kallmann's syndrome gene (KAL1) affects the migratory activity of gonadotropin-releasing hormone (GnRH)-producing neurons.

X-linked Kallmann's syndrome (KS) is a genetic disease characterized by anosmia and hypogonadism due to impairment in the development of olfactory axons and in the migration of gonadotropin-releasing hormone (GnRH)-producing neurons. Deletions or point mutations of a gene located at Xp22.3 (KAL1) are responsible for the disease. This gene encodes for a secreted heparin-binding protein (KAL or anosmin-1) which exhibits similarities with cell-adhesion molecules. In the present study, we show for the first time a direct action of anosmin-1 on the migratory activity of GnRH neurons. Specifically, we exposed immortalized migrating GnRH neurons (GN11 cells) to conditioned media (CM) of COS or CHO cells transiently transfected with human KAL1 gene in microchemotaxis and collagen gel assays. We found that anosmin-1-enriched media produced a cell-specific chemotactic response of GN11 cells. None of the CM enriched on three forms of anosmin-1 carrying different missense mutations (N267K, E514K and F517L) found in patients affected by X-linked KS affected the chemomigration of GN11 cells. Anosmin binds to the GN11 cell surface by interacting with the heparan sulphate proteoglycans, and the chemotactic effect of anosmin-1-enriched CM can be specifically blocked by heparin or by heparitinase pretreatment. These results strongly suggest an involvement of anosmin-1 in the control of the migratory behaviour of GnRH neurons and provide novel information on the pathogenesis of KS.

Animals↗