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Three models for the perception of odor molecules are suggested for the first time by experimental data. These studies illustrate how the nose may smell. Moreover, they suggest additional role(s) for odor receptors within and outside the olfactory system.
The present study extended previous work on olfactory dysfunction (odor identification deficits) by using the Pocket Smell Test (PST) to discriminate between groups of patients with Alzheimer's disease (AD), vascular dementia (VaD), and major depression (MD). Sixty patients meeting the DSM-IV criteria for either AD, VaD, or MD (20 per group) underwent assessment with the PST, a three-item screening measure of odor identification, and the Mini-Mental State Examination (MMSE). Patients with AD scored significantly lower than patients with either VaD or MD on the PST, even after controlling for MMSE scores. A PST score of > or =1 (i.e., 1 or 0 correct) discriminated between patients with and without AD with a classification accuracy of 95% (sensitivity 100%, specificity 92.5%). Olfactory assessment may be of diagnostic utility in the differential diagnosis of AD versus VaD versus MD in elderly patients.
Two major causes of spoiled food smells such as fatty, fishy off-flavors are alkylamines liberated by bacterial actions and aliphatic acids-aldehydes generated by lipid oxidation. Using the method of intrinsic signal imaging, we mapped alkylamine-responsive glomeruli to a subregion of the aliphatic acid-responsive and aldehyde-responsive cluster in the odor maps of rat olfactory bulb. Extracellular single-unit recordings from mitral-tufted cells in the subregion showed that individual cells responded to the alkylamines in addition to acids and aldehydes. Responses of mitral-tufted cells tended to last for a long period (5-88 sec) even after the cessation of the alkylamine stimulation. These results suggest that the subregion is part of the representation of the fatty, fishy odor quality. Fennel and clove, spices known to add flavor and mask the fatty, fishy odor, activated glomeruli in the surrounding clusters and suppressed the alkylamine-induced and acid-aldehyde-induced responses of mitral cells, suggesting that the odor masking is mediated, in part, by lateral inhibitory connections in the odor maps of the olfactory bulb.
Asymptomatic bacteriuria is considered a transient and benign condition in the geriatric population. Before a diagnosis of a urinary tract infection (UTI) can be made, symptoms and significant bacteriuria must be present. One of these symptoms is malodorous urine. Other symptoms of a UTI, typical in the younger population, have been found to be absent or misleading in the older adult population. Though early detection of UTIs improves outcomes, unnecessary laboratory tests are costly and time-consuming, and may encourage inappropriate antibiotic therapy. The purpose of this study was to determine if urine odor is an accurate predictor of a UTI in the older adult incontinent nursing home population. Ninety-seven recently wet incontinence pads of residents in six Midwestern nursing homes were evaluated for odor within 1 hour of voiding. These results were compared to microscopy and culture results of clean-catch urine samples from these individuals. Defining a UTI as either bacteriuria or bacteriuria and pyuria, using urine odor to identify a UTI resulted in error in one third of cases. Results of this study indicate smell of urine in incontinence pads may be an absent or misleading symptom for UTIs in elderly nursing home residents.
Lost or impaired smell or taste should be taken seriously, as it puts a person at higher risk for toxic exposures, such as gas leaks, smoke, and rotting food, and it also takes away the enjoyment of some of life's pleasures, such as the fragrance of flowers or the taste of good food or fine wine. In many patients, the loss follows a viral upper respiratory tract infection, and the only real treatment is to reassure patients that the problem may resolve if the damaged sensory cells regenerate. In other patients, the loss has more subtle causes and deserves a careful investigation and appropriate treatment. This article reviews the proper steps to take when investigating and treating chemosensory difficulties.
A screening test of olfaction was developed with reusable diskettes as applicators of 8 different odorants. Using a questionnaire with illustrations, the test was designed as a triple forced multiple choice test resulting in a score of 0 to 8 correct answers. To validate the test, 102 volunteers with normal olfaction, as well as 22 patients with subjective hyposmia or anosmia, were tested. To compare the developed test with an already validated method, the same persons also performed the sniffin' sticks screening test. The results indicate that the screening test with smell diskettes recognizes patients with normal olfaction and consistently distinguishes them from patients with hyposmia or anosmia.
A 71-year-old woman awoke one morning to find that she perceived all aromas, odors, and fragrances as smelling like burnt toast. Over the next three years, numerous studies and therapeutic trials failed to elicit the cause of her dysosmia or to provide relief. Finally, the demonstration of small infarcts as seen on a brain MRI suggested that an infarct near the olfactory pathway was responsible for the sudden onset and the 11 year persistence of her unique paromia.
Two experiments were performed to determine the effect of taste and odor stimuli on secretion rate of salivary IgA in young and elderly individuals. In Experiment 1, three stimuli were applied to the tongue: 1) "flavor" drops (60% sugar, 5% cocoa powder, and 0.1 % Irish cream odor); 2) sugar (60%); and 3) water. In Experiment 2, four different foods (chicken broth, onion soup, corn, and carrots) were tested with and without monosodium glutamate (MSG). The stimuli in both experiments were delivered three times in a one hour period: t=0, t=30 minutes, t=60 minutes. The results of Experiment 1 indicated that application of sugar (taste alone) and flavor (taste and odor combined) to the tongue induced significantly higher secretion rates of sIgA than the application of water in both elderly and young subjects. In addition, flavor application produced significantly higher secretion rates of sIgA than sugar application alone. Secretion rates of sIgA in young persons were significantly higher than those in elderly persons. In Experiment 2, the increase in secretion rate of sIgA at 30 and 60 minutes for each food with MSG was greater than the same food without MSG for the elderly subjects. The increases in secretion rates of sIgA were produced by elevated salivary flow (Experiments 1 and 2) as well as increased absolute concentrations of sIgA (Experiment 1). The elevation of absolute concentrations of sIgA by chemosensory stimuli may involve neural-immune connections. The improvements in salivary flow and secretory immunity by repeated taste and smell stimulation found here have clinical potential for treatment of immune deficiencies and dry mouth which frequently occur in elderly individuals.
Chemosensory disorders have been receiving increasing clinical attention but remain a difficult diagnostic problem. With the development of several well-standardized testing methods, taste or smell loss can now be verified, and this has added to knowledge concerning the common causes of dysfunction. Diagnosis typically rests upon the history and physical examination, but, except in the case of obstructive nasal and sinus pathologic conditions, therapy usually remains elusive.
A 24-year-old man was admitted to hospital with pneumonia. On admission he was seen to have an asymmetrical build. During treatment of the lung infiltrate his clinical condition deteriorated. On the third day he coughed up great quantities of fluid which had a urine-like smell. The concentration of creatinine in this fluid was the same as in urine. On X-ray of the thorax, a massive accumulation of pleural fluid was seen. Shortly after aspiration of 1000 ml of pleural fluid the patient died. At autopsy, an ectopic kidney was found in the left thoracic cavity. The pneumonia had caused an abscess that had broken into the pelvis of this ectopic kidney causing the loss of urine into the pleural cavity (urothorax) and 'uroptysis'. On the basis of anatomical and embryological aspects it is debatable if this case was genuine. It is in fact a duplication of a case report published in this journal in 1923 the reliability of which was never clarified. Biographical information from Professor A. Querido (1901-1983) which has since become available indicates that the case was faked by mischievous medical students preparing for their examinations. They had never imagined that the editors might actually accept it for publication. The case report of 1923 has now been retracted.
Olfactory disorders may have several causes. Nasal polyposis or chronic sinusitis can result in nasal obstructions that block the access of odorants to the olfactory epithelium, and this can explain the development of olfactory disorders. On the other hand, when nasal endoscopy has revealed that the nasal cleft is free of inflammatory or tumoural disease, olfactory disorders may be explained by neuroepithelial or central nervous system disturbances. This paper will provide information about current approaches to smell disorders in otorhinolaryngology. Major causes will be reviewed as outcomes after medical or surgical treatment. An algorithm will also be given to standardise clinical investigations, including psychophysical olfactory testing, imaging and electrophysiological examinations.
Based on the experience of the Olfactogustometry Laboratories in Halle and in Poznan, a proposal of clinical terminology and systematization of smell and taste disorders has been presented. Individual interpretation of the data from anamnesis in relation to the findings of the olfactogustometric investigations were stressed as indispensable.
We present our experiences of olfactometry and gustometry on 798 patients. The results show the necessity of combining tests for both taste and smell. They are essential components of the complete neuro-otological examination and should remain in the otorhinolaryngologist's repertoire.
This article describes the anatomy and physiology of the gustatory and olfactory organs in man. Dysfunction of these senses is closely examined with respect to etiology, diagnosis, and treatment. Taste and smell are closely interrelated. An influence on the function of one sense often affects the function of the other sense.
The article deals with the case of a patient who had a partial gastrectomy and developed a vitamin B12 deficiency syndrome with anemia, myelopathy and complete loss of the senses of taste and smell. Regression of the symptoms followed liberal dosing with vitamin B12.
An instrument is presented which helps the laryngectomee to smell. It consists of a tube placed between tracheostoma, mouth and nose. The laryngectomized person is able to ventilate his nose with the help of this aid. Moreover, it also aids in blowing the nose and inhaling in case of nasal catarrh.
Loss of the sense of smell can be easily confirmed in any physician's office by having the patient try to identify various odors. The etiology of anosmia can be extremely varied, including nasopharyngeal disorders such as rhinitis and tumors; neurologic conditions such as head trauma, neoplasms, vascular lesions and infections of the central nervous system; viral infections; familial and congenital disorders; drugs; industrial exposure; endocrine diseases, and several other disorders. The prognosis of anosmia is guarded, and its treatment depends on the etiology.
Dried flower of A. alliaceum when fed at 2% level in diet for 6 weeks to experimental rats rendered hypercholesterolemic by cholesterol feeding, exhibited blood cholesterol lowering effect. Cholesterol lowering efficacy of these garlic smelling flowers was similar to garlic oil fed at 0.002% level. Animals fed A. alliaceum flowers excreted higher amounts of neutral and acidic sterols in faeces similar to onion or asafoetida fed (at 2% dietary level) rats. A. alliaceum significantly lowered the absorption of dietary cholesterol from intestine like other sulfur containing spices, viz. garlic oil, onion and asafoetida. It is inferred from this study that limitation in intestinal cholesterol absorption is responsible for cholesterol lowering effect of this flower in hypercholesterolemic animals.