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Biomedical subjects

S Nordin

Publications and source records attributed to S Nordin.

At least 19 recordsLinked to original sources
PubMed2001

Comparison of safety and immunogenicity of a Vi polysaccharide typhoid vaccine with a whole-cell killed vaccine in Malaysian Air Force recruits.

OBJECTIVE: To carry out a comparative study of the safety and immunogenicity of Vi polysaccharide vaccine against whole-cell killed (WCK) typhoid vaccine. METHODS: The study was carried out on young adult recruits (aged 18-25 years) of the Malaysian Air Force. A total of 125 subjects received the Vi polysaccharide vaccine and 114 received the WCK vaccine. FINDINGS: The Vi vaccine was significantly less reactogenic than the WCK vaccine with regard to systemic and local reactions. Following administration of the Vi vaccine, seroconversion rates (defined as the percentage of subjects with a 4-fold rise of baseline antibody level) of 75.5% and 67% were observed at 2 weeks and 6 weeks, respectively, after immunization, compared with 25% and 31.3% among recipients of the WCK vaccine. Of the 110 Vi vaccinees with serological data, 21 (19%) had high, seroprotective, pre-immunization levels of anti-Vi antibodies (> or = 1 microgram/ml). The majority of subjects in this group came from a region in Malaysia which is known to have high typhoid endemicity. Interestingly, these antibody levels were boosted considerably following administration of vaccine at a level that was 5-fold higher than in subjects with low pre-immunization levels. In contrast, the seroconversion rates in those receiving the Vi vaccine were higher in subjects with low pre-immunization levels of anti-Vi antibodies (76-84%), compared to those with protective levels of > or = 1 microgram/ml prior to immunization (48-57%). CONCLUSIONS: The study reaffirms the safety and efficacy of the Vi polysaccharide vaccine and identifies a hitherto unrecognized advantage in its use, i.e. it is a potent immunogen that boosted considerably the protective antibody levels among a significant number of immunologically sensitized individuals living in typhoid-endemic regions.

Adolescent↗
PubMed2000

Olfactory event-related potentials and aging: normative data.

Unlike the clinical usages of evoked potentials (e.g. brain stem auditory evoked potentials for the assessment of auditory function), normative data for the olfactory event-related potential (OERP) have been unavailable. The principal objective was to establish normative data across the human life span for OERPs with a given set of parameters. Participants were 140 persons from seven age groups (16-19, 20-29, 30-39, 40-49, 50-59, 60-69 and 70-79 years of age), with equal numbers of males and females, screened for nasal health and dementia. The odor stimulus was amyl acetate, presented at nasal temperature in a humidified airstream delivered by an air-dilution olfactometer at a constant flow rate, using a 60-s inter-stimulus interval. OERPs were recorded at Fz, Cz, and Pz electrode sites, amplified and averaged over trials. Amplitudes of the N1/P2 and P3 and latencies of the P2 and P3 were analyzed. Processing speed decreased at a constant rate over decades for the sensory (P2 latency) as well as cognitive (P3 latency) components. Decline in amplitude over decades was also apparent. Normative data will be useful in research on olfactory function and in clinical assessment of olfactory functional status.

Adolescent↗
PubMed1999

Olfactory event-related potentials in young and elderly adults: evaluation of tracking task versus eyes open/closed recording.

The purpose of the present study was to evaluate olfactory event-related potentials (OERPs) elicited by amyl acetate from subjects performing a visuomotor tracking task compared with the no-task conditions of eyes open and eyes closed. Task condition did not produce any reliable effects for any amplitude measure. Task type weakly influenced only P2 latency. Elder adults evinced smaller P2 and N1/P2 amplitudes and longer N1 and P2 latencies than young adults. The results suggest that tracking task performance is not necessary to obtain robust OERPs from normal subjects of a wide age range.

Adult↗
PubMed1998

Abnormality of semantic network in patients with Alzheimer's disease. Evidence from verbal, perceptual, and olfactory domains.

A series of studies was initiated to model the organization of semantic memory in Alzheimer's disease (AD) patients using multidimensional scaling (MDS) and Pathfinder analyses. The resulting models (cognitive maps or semantic networks) embed studied stimuli in a coordinate space or network where distances between points are assumed to reflect psychological proximity between items. The organization of semantic networks in verbal and sensory domains were modeled based upon the frequency of the subject's choice of two concepts as most alike. Results suggested that while the organization of concepts in the semantic networks of AD patients was primarily based upon a concrete perceptual dimension in both verbal and olfactory domains, those of normal controls subjects were predominantly organized by an abstract conceptual attribute. Also, networks of AD patients were more complex and chaotic than normal, that is, they consisted of more unnecessary connections and of atypical strengths of association between concepts.

Alzheimer Disease↗
PubMed1998

Odor memory in normal aging and Alzheimer's disease.

The ability in normal elderly to verbally recall previously presented odors and to learn this task across trials was studied by applying a design which compared performance on the California Verbal Learning Test (CVLT) with an analogous odor test. Results suggest that both immediate and delayed recall of odors, both free and cued, as well as the ability to learn across trials is impaired in normal aging, perhaps more so for olfaction than for audition, which can be referred to poor use of semantic-clustering strategies and poor identification. Olfactory decline in memory in normal aging is, however, far from as affected as in Alzheimer's disease (AD). Two studies of persons with questionable AD demonstrated significant deficits in both recognition memory and identification of odors. Although further research is required, the findings from these 'pre-clinical' cases imply that performance on olfactory-mediated tasks may contribute to early diagnosis of AD.

Aged↗
PubMed1998

Effects of nasal-airway volume and body temperature on intranasal chemosensitivity.

Interrelations between intranasal detection sensitivity for odor (H2S) and pain (CO2), nasal-airway volume (acoustic rhinometry), and body temperature were studied in young, healthy men across the diurnal cycle. The results showed a weak but statistically significant negative correlation between nasal volume and odor threshold and a weak but positive correlation between body temperature and odor threshold.

Adult↗
PubMed1998

The Scandinavian Odor-Identification Test: development, reliability, validity and normative data.

The Scandinavian Odor-Identification Test (SOIT) was developed to address the need for a culturally valid odor-identification test for clinical use on the Scandinavian population that (i) has good ability to generalize performance to olfactory status, (ii) assesses olfactory and trigeminal function separately, (iii) requires only limited cognitive demands, (iv) has normative data and good sensitivity and specificity, and (v) is fast, easy to administer and inexpensive. Sixteen odorous test stimuli were selected that were relatively identifiable, familiar, strong in intensity and pleasant according to healthy participants. Four response alternatives were then selected for each test stimulus based on a confusion matrix of identification rates obtained from healthy participants, in a manner that controlled for task difficulty. Results on the SOIT from healthy persons and hyposmic patients showed satisfactory test-retest reliability, split-half reliability and validity. Cut-off scores for olfactory diagnosis (normosmia, hyposmia, anosmia) based on normative data obtained from 171 healthy persons showed a satisfactory sensitivity and specificity of the SOIT. Assessment of 22 anosmic patients with the SOIT revealed that three of the test stimuli were significant trigeminal stimulants.

Adolescent↗
PubMed1997

Olfactory dysfunction for pyridine and dementia progression in Alzheimer disease.

OBJECTIVE: To investigate whether odor detection sensitivity for pyridine, suggested by previous research not to be affected, is impaired in Alzheimer disease (AD) and whether an association exists between odor threshold and both degree of dementia and rate of dementia progression in AD. METHOD: The method of constant stimuli was used to determine odor thresholds for pyridine in 18 patients with AD (Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised and National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria) and 16 healthy elderly control subjects. All participants were carefully examined with medical and neuropsychological tests. RESULTS: Six patients with AD but none of the controls were anosmic (total olfactory loss) to pyridine, and the 12 nonanosmic patients had significantly higher detection thresholds (50% probability for detection, 323 parts per billion [ppb]) than did the controls (50% probability for detection, 105 ppb). In addition, an association was found between odor threshold and both degree of dementia and rate of dementia progression in AD. CONCLUSIONS: In contrast to previous findings, our results provide evidence that odor sensitivity in AD is impaired for pyridine. Odor sensitivity, in addition to other suggested predictors of progression rate, may be of interest for defining subgroups of AD or for clinical prognostic judgments of single patients.

Aged↗
PubMed1997

Perceptual learning in olfaction: professional wine tasters versus controls.

By having professional wine tasters and controls perform olfactory tasks of absolute detection (1-butanol), discrimination (lemon and cloves), and identification (common household odors), the present two experiments studied (a) if perceptual odor learning takes place from odor experience acquired under nonlaboratory conditions, (b) if this learning generalizes to odors for which experience is limited, and (c) if generalized learning can be referred to increased general interest for odors that increases attention to odorous features. The results showed that whereas wine tasters were not better than controls on detection, they were superior to controls on discrimination and identification, the latter due to only a few odors. Ratings of experience with certain odors during professional evaluation suggest that generalized perceptual learning may take place in discrimination but not in identification. Wine tasters did not show more general interest for odorous features than did controls. The nonsuperiority in detection may be explained by the fact wine tasters have no professional experience of a detection task per se, implying that perceptual odor learning does not generalize from the olfactory tasks of discrimination and identification to detection.

Adult↗
PubMed1997

Odor learning, recall, and recognition memory in young and elderly adults.

use of an odor learning test and the California Verbal Learning Test in young and elderly adults enabled comparison of age-related effects on recall and recognition memory. Assessment of odor identification further enabled study of which odor function (recall, identification, recognition) is most affected by aging, the odor functions' interrelationships, and predictors of odor recall. Results suggested that both recall and recognition were significantly affected by aging and that the odor-recall decline cannot simply be referred to poor identification. Very similar age-related effect sizes were found for the 3 types of odor functions. Finally, the combined ability to encode, store, and retrieve odors appears to predict overall recall performance (including its identification component) better than do identification and recognition.

Adolescent↗
PubMed1997

Chronobiology of nasal chemosensitivity: do odor or trigeminal pain thresholds follow a circadian rhythm?

Odor and trigeminal pain thresholds were studied four times each at 24:00, 04:00, 08:00, 12:00, 16:00 and 20:00 h in randomized order on different days in five healthy male volunteers. No circadian rhythm of olfactory or trigeminal thresholds were observed. However, the variability of odor, but not pain thresholds, increased from 04:00 h (thresholds between 0.4 and 1.2 p.p.m.) to 16:00 h (thresholds between 0.1 and 2 p.p.m.). It is hypothesized that environmental influences contribute to this increase in variance.

Adult↗
PubMed1996

Prevalence and assessment of qualitative olfactory dysfunction in different age groups.

The prevalence of parosmia and phantosmia among 363 chemosensory and nasal/sinus patients was studied, as was the accuracy with which our clinical questionnaire could assess these dysfunctions. We then investigated whether patients with parosmia or phantosmia, matched for odor intensity, perform poorer on odor identification than do patients with no dysosmia. More than 40% of the study group evidenced either parosmia (18.7%) and/or phantosmia (25.6%), a finding that suggests that more attention should be paid by the medical practitioner in addressing qualitative olfactory dysfunction. Furthermore, it appears that assessment of these dysfunctions may aid in differential diagnosis, and that questionnaires can be used with reasonable validity irrespective of the patient's age. Finally, the results imply that parosmia may be reflected in a discrepancy between odor identification and detection.

Adult↗
PubMed1996

Hip configuration and function in bladder exstrophy treated without pelvic osteotomy.

Nine children with congenital bladder exstrophy treated without pelvic osteotomy were analyzed clinically and radiologically at a mean age of 13 years (range 9-16 years). The acetabular and femoral version angles were measured by computed tomography (CT) imaging. Two of the children had a slight waddling gait, but none of them had any pain and they could participate in sports without problems. They had a normal range of hip movements and a normal foot progression angle. The acetabulum was retroverted by an average of 5 degrees, but was balanced by an increased anteversion of the femur which on the average was 10 degrees-20 degrees higher than normal. The femoral head in all hips was spherical, and no hip showed dysplasia. In bladder exstrophy, retroversion of the acetabulum was balanced by an increased anteversion of the femur, resulting in a normal range of hip movements and a normal gait in later childhood.

Adolescent↗
PubMed1995

Sensory- and memory-mediated olfactory dysfunction in Huntington's disease.

Neuropathology in Huntington's disease (HD) known to project to areas that process olfactory information raises the questions of which olfactory function, if any, is most affected in HD, and how to explain such dysfunction in terms of olfactory sensitivity and cognition. These questions were studied by comparing HD patients and controls (matched for age, gender, and education) on absolute detection, intensity discrimination, quality discrimination, short-term recognition memory, and lexical- and picture-based identification for odor. Taste or vision were used as comparison modalities. The results suggest that whereas odor-recognition memory is not affected in patients with HD, these patients have impaired olfactory functioning with respect to absolute detection, intensity discrimination, quality discrimination, and identification. The three latter impairments were significantly explained by poor detection sensitivity. Odor identification was the function most affected.

Adult↗
PubMed1995

Odor identification as an early marker for Alzheimer's disease: impact of lexical functioning and detection sensitivity.

The impact of lexical functioning and detection sensitivity on the deficit of odor identification in Alzheimer's disease (AD) was studied in persons diagnosed with probable and questionable AD. Tests consisted of lexical-based odor identification, lexical-based picture identification, picture-based odor identification, and odor-detection threshold. Results suggest (1) that odor identification is poorer than picture identification in probable and questionable AD, (2) that odor identification continues to be poor even when lexical demands are eliminated, (3) that odor detection does contribute to the odor-identification deficit, but does not account for it completely, and (4) that odor identification tests have a correct classification rate of 83-100%. Odor identification tests can be very useful tools in diagnosing AD and should be considered an important addition to existing diagnostic test batteries.

Aged↗
PubMed1995

Reliability and validity of electrogustometry and its application to young and elderly persons.

Electrogustometric-threshold assessment demonstrated excellent test-retest reliability, good bilateral correspondence and age-related differences. Tactile and stimulus-related descriptors of the sensation elicited at detection threshold, as well as a lack of correlation between whole-mouth chemical thresholds and anterior tongue electrogustometric thresholds, raise questions for future research.

Adult↗
PubMed1995

Unawareness of smell loss in normal aging and Alzheimer's disease: discrepancy between self-reported and diagnosed smell sensitivity.

Awareness of loss in smell sensitivity was assessed in 80 normal elderly subjects, 80 patients with probable Alzheimer's disease (AD), and 80 patients with sinusitis by comparing measured smell sensitivity to questionnaire-based, self-reported sensitivity. Both AD patients and sinusitis patients had significantly poorer diagnosed smell sensitivity than the normal elderly. Both patient groups had thresholds which on average were about nine times more concentrated than those of the normal elderly. However, 74% of the AD patients and 77% of the normal elderly with smell loss reported normal smell sensitivity. In contrast, only 8% of the sinusitis patients with loss reported normal smell sensitivity.

Adolescent↗