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PubMed2006

Association of a bovine CXCR2 gene polymorphism with neutrophil survival and killing ability.

Recent research in our lab has demonstrated a significant association between the incidence of subclinical mastitis and specific polymorphisms of the CXCR2 gene in Holstein dairy cows. This gene encodes a receptor for interleukin-8 (IL-8), a key regulator of neutrophil migration, killing and survival. Because of the importance of this gene in neutrophil function, we hypothesized that differences in neutrophil killing and survival may exist among the CXCR2 genotypes and potentially contribute to the observed variation in intramammary infections. To test this hypothesis, neutrophils were isolated from cows representing each CXCR2 +777 genotype (GG, GC or CC) and tested for suppression of apoptosis, reactive oxygen species (ROS) generation, glutathione levels, and bactericidal activity. A significant increase in survival was observed in neutrophils from cows with a CC genotype when compared to those with a GG genotype in response to IL-8, but not dexamethasone. In contrast, a significant reduction in neutrophil ROS generation in response to phorbol-13-myristate-12 acetate (PMA) was observed in cows with a CC genotype when compared to those with a GG genotype. However, no differences in bactericidal activity or glutathione levels were observed among genotypes. The functional activity of neutrophils from cows heterozygous for this polymorphism was intermediate between those with homozygous genotypes for those assays where differences were observed among homozygous genotypes. In summary, our results suggest that neutrophils from Holstein cows with different CXCR2 genotypes vary in their ability to suppress apoptosis and produce ROS. These differences have the potential to influence overall neutrophil function and may partially explain the variation observed with respect to mastitis in vivo. These results provide a foundation for future research aimed at better understanding the basic differences between dairy cows genetically more or less susceptible to mastitis and has the potential to provide novel preventive and therapeutic measures against inflammatory diseases such as mastitis.

Animals↗

PubMed1993

Wharton's jelly in the umbilical cord. A study of its quantitative variations and clinical correlates.

A frozen segment was prepared from each of 398 consecutively collected umbilical cords after stripping them of blood. Three cross-sections were obtained from each cord, and dye imprints were made. Their surface area was measured by placing a transparency with a grid of squares over the imprint and counting the number of squares it occupied. An average of these three cross-sectional areas was taken to estimate the quantity of Wharton's jelly at any point along the umbilical cord. Of the 14 maternal and fetal variables studied, those that were found to be independently related to the estimated quantity of Wharton's jelly in the umbilical cord were male gender (P = < .01), weight of the fetus (P = .05) and maternal prepregnancy weight (P = < .01). These variables, however, explained only 7% of the observed variation in quantity. A further 3.3% was explained by measurement error, leaving 89.7% of the observed variation unexplained.

Adult↗

PubMed2006

A detailed observation of variations of the facial artery, with emphasis on the superior labial artery.

The reconstruction of lip defects through the use of the Abbe flap and other lip flap procedures involves surgical manipulation of one of the major branches of the facial artery, specifically the superior labial artery (SLA). We examined 284 hemifaces derived from 142 formalin fixed cadavers. Observations regarding the distribution patterns of the facial artery were recognized and categorized into five Types, labeled "A" through "E". Type A (135, 47.5%): facial artery bifurcates into SLA and lateral nasal (the latter gives off inferior and superior alar and ends as angular); Type B (110, 38.7%): similar to Type A, except lateral nasal terminates as superior alar (angular artery is absent); Type C (24, 8.4%): facial artery terminates as SLA; Type D (11, 3.8%): angular artery arises directly from facial arterial trunk rather than as the termination of lateral nasal, with the facial artery ending as superior alar; Type E (4, 1.4%): facial artery terminates as a rudimentary twig without providing any significant branches. Furthermore, we were able to categorize variations within each Type. Sub-Type variations were examined in Types A through C (A: 1-7; B: 1-4; C: 1-3). Our aim was to equip both the anatomist and surgeon with a more thorough understanding of the vasculature of the face, as well as to enable plastic surgeons to have a more confident approach to reconstructive procedures in this region.

Adult↗

PubMed2001

The effect of Mg2+ on cardiac muscle function: Is CaATP the substrate for priming myofibril cross-bridge formation and Ca2+ reuptake by the sarcoplasmic reticulum?

Kinetics are established for the activation of the myofibril from the relaxed state [Smith, Dixon, Kirschenlohr, Grace, Metcalfe and Vandenberg (2000) Biochem. J. 346, 393-402]. These require two troponin Ca2+-binding sites, one for each myosin head, to act as a single unit in initial cross-bridge formation. This defines the first, or activating, ATPase reaction, as distinct from the further activity of the enzyme that continues when a cross-bridge to actin is already established. The pairing of myosin heads to act as one unit suggests a possible alternating mechanism for muscle action. A large positive inotropic (contraction-intensifying) effect of loading the Mg2+ chelator citrate, via its acetoxymethyl ester, into the heart has confirmed the competitive inhibition of the Ca2+ activation by Mg2+, previously seen in vitro. In the absence of a recognized second Ca2+ binding site on the myofibril, with appropriate binding properties, the bound ATP is proposed as the second activating Ca2+-binding site. As ATP, free or bound to protein, can bind either Mg2+ or Ca2+, this leads to competitive inhibition by Mg2+. Published physico-chemical studies on skeletal muscle have shown that CaATP is potentially a more effective substrate than MgATP for cross-bridge formation. The above considerations allow calculation of the observed variation of fractional activation by Ca2+ as a function of [Mg2+] and in turn reveal simple Michaelis-Menten kinetics for the activation of the ATPase by sub-millimolar [Mg2+]. Furthermore the ability of bound ATP to bind either cation, and the much better promotion of cross-bridge formation by CaATP binding, give rise to the observed variation of the Hill coefficient for Ca2+ activation with altered [Mg2+]. The inclusion of CaADP within the initiating cross-bridge and replacement by MgADP during the second cycle is consistent with the observed fall in the rate of the myofibril ATPase that occurs after two phosphates are released. The similarity of the kinetics of the cardiac sarcoplasmic reticulum ATPase to those of the myofibril, in particular the positive co-operativity of both Mg2+ inhibition and Ca2+ activation, leads to the conclusion that this ATPase also has an initiation step that utilizes CaATP. The first-order activation by sub-millimolar [Mg2+], similar to that of the myofibril, may be explained by Mg2+ involvement in the phosphate-release step of the ATPase. The inhibition of both the myofibril and sarcoplasmic reticulum Ca2+ transporting ATPases by Mg2+ offers an explanation for the specific requirement for phosphocreatine (PCr) for full activity of both enzymes in situ and its effect on their apparent affinities for ATP. This explanation is based on the slow diffusion of Mg2+ within the myofibril and on the contrast of PCr with both ATP and phosphoenolpyruvate, in that PCr does not bind Mg2+ under physiological conditions, whereas both the other two bind it more tightly than the products of their hydrolysis do. The switch to supply of energy by diffusion of MgATP into the myofibril when depletion of PCr raises [ATP]/[PCr] greatly, e.g. during anoxia, results in a local [Mg2+] increase, which inhibits the ATPase. It is possible that mechanisms similar to those described above occur in skeletal muscle but the Ca2+ co-operativity involved would be masked by the presence of two Ca2+ binding sites on each troponin.

Adenosine Triphosphatases↗

PubMed1992

The quality and relevance of peripheral neuropathy data on a diabetic clinical information system.

Routinely collected peripheral neuropathy data entered on a diabetic clinical information system since 1979 have been audited for completeness, consistency, accuracy (inter-observer variation), validity by comparison with biothesiometry, and relevance by life table analysis for foot ulceration. Peripheral neuropathy was defined by a neuropathy disability score > or = 4. The data were 98% complete. Forty-nine of 3405 (1.4%) had inconsistent records. Agreement between observers for clinical examination was significant (p < 0.05) for aggregate neuropathy score and its individual components except the knee jerk: Kappa score for observer variation for neuropathy score 0.56 (95% confidence interval 0.36-0.76). There was good agreement between neuropathy defined as aggregate score > or = 4, and as combined vibration perception thresholds for both feet > 60 V: Kappa statistic 0.62 (95% confidence interval 0.44-0.80). The chance of developing a foot problem in 3 years increased from 3% for patients with a score of zero to 45% for people with a score of between 9 and 12. We conclude that the calculation of a clinical neuropathy score is a simple, valid and relevant method for diabetes care both in hospital and the community. When combined with palpation of peripheral pulses most patients at risk of foot ulceration can be identified allowing targeting of preventive chiropody and orthotic resources.

Diabetic Neuropathies↗

PubMed2006

Impact of institutional review board practice variation on observational health services research.

OBJECTIVE: To describe, qualitatively and quantitatively, the impact of a review by multiple institutional review boards (IRBs) on the conduct of a multisite observational health services research study. DATA SOURCE AND SETTING: Primary data collection during 2002, 2003, and 2004 at 43 United States Department of Veterans Affairs (VA) primary care clinics. DESIGN: Explanatory sequential mixed methods design incorporating qualitative and quantitative elements in sequence. DATA COLLECTION AND ABSTRACTION METHODS: Field notes and documents collected by research staff during a multisite observational health services research study were used in thematic analysis. Themes were quantified descriptively and merged with timeline data. PRINCIPAL FINDINGS: Approximately 4,680 hours of staff time over a 19-month period were devoted solely to the IRB process. Four categories of phenomena impacting research were observed: (1) Recruitment, retention, and communication issues with local site principal investigators (PIs). Local PIs had no real role but were required by IRBs. Twenty-one percent of sites experienced turnover in local PIs, and local PI issues added significant delay to most sites. (2) Wide variation in standards applied to review and approval of IRB applications. The study was designed to be qualified under U.S. government regulations for expedited review. One site exempted it from review (although it did not qualify for exemption), 10 granted expedited review, 31 required full review, and one rejected it as being too risky to be permitted. Twenty-three required inapplicable sections in the consent form and five required HIPAA (Health Insurance Portability and Accountability Act of 1996) consent from physicians although no health information was asked of them. Twelve sites requested, and two insisted upon, provisions that directly increased the risk to participants. (3) Multiple returns for revision of IRB applications, consent documents, and ancillary forms. Seventy-six percent of sites required at least one resubmission, and 15 percent of sites required three or more (up to six) resubmissions. Only 12 percent of sites required any procedural or substantive revision; most resubmissions were editorial changes to the wording of the consent document. (4) Process failures (long turnaround times, lost paperwork, difficulty in obtaining necessary forms, unavailability of key personnel at IRBs). The process required from 52 to 798 (median 286) days to obtain approval at each site. CONCLUSIONS: Several features of the IRB system as currently configured impose costly burdens of administrative activity and delay on observational health services research studies, and paradoxically decrease protection of human subjects. Central review with local opt-out, cooperative review, or a system of peer review could reduce costs and improve protection of human subjects.

Ethics Committees↗

PubMed2005

Amplified fragment length polymorphism and metabolomic profiles of hairy roots of Psoralea corylifolia L.

A reproducible protocol for establishment of hairy root cultures of Psoralea corylifolia L. was developed using Agrobacterium rhizogenes strain ATCC 15834. The hairy root clones exhibited typical sigmoid growth curves. Genomic and metabolomic profiles of hairy root clones along with that of untransformed control were analysed. Hairy root clones, Ps I and Ps II, showed significant differences in their amplified fragment length polymorphism (AFLP) profiles as compared to that of control, besides exhibiting Ri T-DNA-specific bands. These results amply indicate the stable integration of Ri T-DNA into the genomes of these clones. Further, the variations observed between clones in the AFLP profiles suggest the variable lengths and independent nature of Ri T-DNA integrations into their genomes. An isoflavonoid, formononetin, and its glycoside were present only in the hairy root clones while they were absent in the untransformed control. Variations observed in the metabolite profiles of these clones may be attributed to the random T-DNA integrations and associated changes caused by them in the recipient genomes. GC/MS analyses revealed the production of three and six clone-specific compounds in Ps I and Ps II, respectively, suggesting that the clones are dissimilar in their secondary metabolism. HPLC/UV-MS analyses disclosed substantial increases in the total isoflavonoids produced in Ps I (184%) and Ps II (94%) compared to untransformed control.

Cell Culture Techniques↗

PubMed2000

[Comparison of primary care teams in Barcelona according to management formulas].

OBJECTIVE: The aim of the study is to compare, among socio-economically similar areas, the use of medical services, clinical practice and pharmacy costs depending on the how the primary healthcare teams, that provide these services, are organized according to different managemental formulas. DESIGN: Descriptive study of the evaluation of health care services. PATIENTS AND METHODS: The population units (basic health areas) attended by the reformed primary health care services in Barcelona were classified into three levels according to the population's socioeconomic status (high, medium or low). For each level, two primary health care teams were selected representing different primary health care providers: "Institut Catala de la Salut"; and others. The influence of both the provision option and the population characteristics on service use, clinical practice and costs of prescription were compared. MAIN RESULTS: The services offered by the two provision options differ. However, the use of medical services is related to the socioeconomic characteristics and not to the option for service provision. Whilst there are no relevant differences in clinical practice between the different options, we observed variations among different primary care teams, notably in referrals to specialists and influenza vaccine coverage. The greater source of variation in prescription costs seems to be related to an external confounding factor. CONCLUSIONS: Empirical data have not identified relevant differences in the pattern of use, clinical practice, or costs between the different options for service provision within the model of reformed primary care services. Observed variations seem to be associated mainly with the population's characteristics, its pattern of health service use or other external confounding factors.

Clinical Laboratory Techniques↗

PubMed1985

Observer performance in assessment of condylar position in temporomandibular joint radiograms.

The condylar position at centric occlusion has been considered important in diagnosis of the temporomandibular joint. The present study describes inter- and intra-observer variation in radiographic assessment of condylar position. One radiogram obtained by using an individualized lateral oblique transcranial projection and three corrected sagittal tomograms from the lateral, central, and medial parts of the joint were selected from each of 31 patients. In the resulting 124 radiograms three observers assessed the position of the condyle as posterior, central, or anterior on two occasions, 3 months apart. Concordant reports for all three observers were found in 63%. The interobserver agreement two by two ranged between 69% and 79%, whereas the intraobserver agreement ranged between 81% and 90%. The observer variation and limitations of radiographic techniques should be considered when the therapeutic implication of condylar position is discussed.

Dental Occlusion, Centric↗

PubMed1987

Expected genetic drift and observed gene variation in a small isolated human population.

Data on the gene frequencies of four blood groups and six polymorphic erythrocyte enzymes were collected in a small population of the Northern Apennines (municipality of Zeri, Tuscany, Italy), whose civic records are available from 1866 on. Starting from the assumption that the mean gene frequencies of large populations of the neighbouring regions may represent a good estimate of the frequencies of the 'mother population' of the isolate, an observed value of the standardized ('Wahlund') variance of gene frequencies was computed and found to be 0.0131. The expected value of the same variance, due to random drift, has been computed on the basis of an evaluation of the immigration to the isolate, drawn from the marriage register of the municipality: this value was 0.0103.

Emigration and Immigration↗

PubMed2000

Effects of pH on cadmium and zinc uptake by the midge larvae Chironomus riparius.

We studied the effect of pH on the uptake of cadmium and zinc by fourth instar larvae of the midge Chironomus riparius within the pH range 5.5-10.0, using chemically defined solutions. The effect of prior acclimation on metal uptake was examined for four pH levels, i.e. pH 5.5, 7.0, 8.0 and 9.5. At least three factors were important in determining the effect of pH on the cadmium and zinc uptake by midge larvae. The effect of pH on metal uptake is the combined result of changes in free metal ion activity, changes in pH of exposure and changes in pH of acclimation, the latter representing a physiological effect. Within each acclimation group metal uptake in larvae increased with increasing pH of exposure in the range 5.5-9.0 but decreased between pH 9.0 and 10.0. Taking into account the decreased free metal ion activity, metal uptake was still high at pH 10.0. A possible explanation for this is that an increase in pH alters the metal uptake process by decreasing the protonation of the binding sites. That is, the biological availability of the free metal ion increases with increasing pH. Among the different pH exposure groups, acclimation had a positive effect up to pH 9.0 but a negative effect between 9.0 and 10.0. Two different uptake models were applied to describe the observed variation in metal uptake. With a non-linear, semi-empirical model, the integration of the different pH effects for the pooled data described no more than 38% of the total variation in cadmium uptake and 36% of the total variation in zinc uptake by midge larvae. When the model was fitted to the uptake data of larvae acclimated to the exposure conditions, 78 and 69% respectively of the variation was described. The second model, a biological ligand model, was not able to discriminate between effects of pH in acclimated and non-acclimated exposure groups. Only for the data of larvae acclimated to the exposure conditions the model could describe a significant amount of the observed variation in metal uptake, R(2) values being comparable to those of the first model. The remaining high undescribed variation could be ascribed to the high natural variation in metal uptake by midge larvae.

Journal Article↗

PubMed2003

Evaluation of a multimodality image (CT, MRI and PET) coregistration procedure on phantom and head and neck cancer patients: accuracy, reproducibility and consistency.

BACKGROUND AND PURPOSE: In radiotherapy planning of head and neck tumors, coregistration of various anatomical (e.g. CT and MRI) and functional (e.g. PET) images is a promising way to improve the delineation of the target volumes. In this paper, we report data on accuracy, reproducibility and consistency of an interactive coregistration procedure in a specifically designed phantom and in a group of patients with primary head and neck tumors. PATIENTS AND METHODS: A phantom and a group of four patients with pharyngo-laryngeal tumors were imaged by CT scan (taken as the reference image), MRI (T1- and T2-weighed sequences) and PET (transmission and FDG emission). Sets of images were coregistered using an interactive rigid coregistration method based on interactive surface segmentation. Translational and rotational displacements relative to the reference CT scan were measured and expressed in terms of accuracy, reproducibility (inter- and intra-observer variation) and consistency (between T1- and T2-weighed MRI). RESULTS: Coregistration accuracy was in the range of 0.8-6.2 mm and 1.2-4.6 mm for the phantom and the patients, respectively. Accuracy was slightly worse in the z direction, and was significantly correlated with the spatial resolution of the imaging modalities, at least for the phantom. Inter- and intra-observer variations were very small and always far below the residual variance. Consistency was perfect except in the y direction. CONCLUSION: Providing adequate set-up is chosen, accurate coregistration of CT, MR and FDG-PET images can be obtained in the head and neck area. Coregistration was consistent and highly reproducible among observers.

Head and Neck Neoplasms↗

PubMed2001

Endodontic retreatment. Aspects of decision making and clinical outcome.

Epidemiological surveys have reported that 25%-35% of root filled teeth are associated with periapical radiolucencies. Descriptive studies have demonstrated that clinicians' decision making regarding such teeth are subject to substantial variation. A coherent model to explain the observed variation has not been produced. In the present thesis a "Praxis Concept theory" was proposed. The theory suggests that dentists perceive periapical lesions of varying sizes as different stages on a continuous health scale. Interindividual variations can then be regarded as the result of the choice of different cut-off points on the continuum for prescribing retreatment. In the present study experiments among novice and expert decision makers gave evidence in favour of the theory. Data also suggested that the choice of retreatment criterion is affected by values, costs of retreatment and technical quality of original treatment. From a prescriptive point of view, the presence of a persistent periapical radiolucency has often been used as a criterion of endodontic "failure" and as an indication for endodontic retreatment. As an alternative decision strategy, the use of decision analysis has been proposed. Logical display of decision alternatives, values of probabilities, utility values (U-values) of the different outcomes and calculation of optimal decision strategy are features of this theory. The implementation of this approach is impeded by the uncertainty of outcome probabilities and lack of investigations concerning U-values. U-values of two periapical health states in root filled teeth (with and without a periapical lesion respectively) were investigated in a group of 82 dental students and among 16 Swedish endodontists. Two methods were used to elicit U-values: Standard gamble and Visual Analogue Scale. Large interindividual variation for both health states were recorded. The difference in U-values between the two health states was found to be statistically significant regardless of assessment method. Compared with Standard gamble Visual Analogue Scale systematically produced lower ratings. U-values were found to change considerably in both the short and long-term. Any significant correlation between endodontists' U-values and retreatment prescriptions could not be demonstrated. Surgical and nonsurgical retreatment were randomly assigned to 95 "failed" root filled teeth in 92 patients. Cases were followed clinically and radiographically for four years postoperatively. At the 12-month recall a statistically significant higher healing rate was observed for teeth retreated surgically. At the final 48-month recall no systematic difference was detected. Patients were found to be more subject to postoperative discomfort when teeth were retreated surgically compared with nonsurgically. Consequently, surgical retreatment tended to be associated with higher indirect costs than a nonsurgically approach. In the final part of the thesis it is argued that retreatment decision making in everyday clinical practice normally should be based on simple principles. It is suggested that in order to achieve the best overall consequence a periapical lesion in a root filled tooth that is not expected to heal should be retreated. Arguments to withhold retreatment should be based on (i) respect for patient autonomy, (ii) retreatment risks or (iii) retreatment costs.

Decision Making↗

PubMed2006

Reliability of mutagen sensitivity assay: an inter-laboratory comparison.

Mutagen sensitivity is regarded as a genetic susceptibility phenotype for various cancers; it is cytogenetically based and probably involves a number of genes from different DNA repair pathways. This assay has been used in a number of laboratories in the field of epidemiology, where it has been investigated and appears to be a useful susceptibility biomarker for epidemiological studies assessing cancer risks at the population level. One concern about phenotypic assays, such as the mutagen sensitivity assay, has been that there could be wide variation in results depending on the timing of the assay (within individual variation), the individual performing the assay (within observer variation) and the laboratory where the assay has been performed (inter-laboratory variation). We conducted an inter-laboratory comparison study between the Memorial Sloan-Kettering Cancer Center and M. D. Anderson, in which we assessed all these concerns. We did not find any significant variation in any of the assays. The correlation was high for all tests. The good concordance rate between laboratories supports the continued use of the mutagen sensitivity assay by different laboratories, and demonstrates its potential to identify at-risk subgroups among normal individuals and cancer patients alike.

Environmental Exposure↗

PubMed1992

[Serum human growth hormone assay. Comparison of six assay kits].

Measurements of human growth hormone (hGH) plasma levels using mono or polyclonal antibodies based on kits are often highly variable depending upon the kit used. We compared six kits commercially available: one based on polyclonal antiserum, five based on monoclonal antisera. We measured 695 sera obtained in short stature children (GH deficiency or normal GH secretory) and adults (normal, hypopituitarism or acromegaly). Our results confirm the variability between the assays. The maximal variation was obtained with SBhGH kit which showed mean results 1.7 fold higher than those obtained with hGH Coatria. Using the OMS 80.205 standard with the six kits, we found a good correlation between the six kits indicating that the standard used in each case was not responsible for the observed variations. This suggest that the different antibodies used in these kits may recognize different isoforms of circulating hGH. In addition variations in reagents used in the different kits may also explain these discrepancies. The variations observed using these six commercially available kits may have important clinical repercussion and especially may impede the diagnosis in hGH deficiency in children.

Adolescent↗

PubMed2002

Modelling mammary metabolism in the dairy cow to predict milk constituent yield, with emphasis on amino acid metabolism and milk protein production: model evaluation.

A model of mammary metabolism has been constructed and parameterized, with milk protein synthesis represented as a function of five essential amino acids (EAA) (Hanigan et al., 2001). Herein the model is evaluated using both the data used to construct the model (reference data) and an independent data set (literature data), and sensitivity to inputs and parameter estimates is assessed. The model predicted metabolite removal well for the reference data with exceptions for glutamate, glucose, and acetate. However, predictions of milk protein synthesis exhibited significant mean positive bias, which apparently was associated with the representation of milk protein synthesis. Adjustment of model parameters removed the mean bias, however, prediction accuracy was still inadequate. Simulation of the single reference experiment containing all critical inputs resulted in predictions of milk protein output that explained 53% of the observed variation, suggesting that the limited accuracy of the model when applied to the entire reference data set was due to assumptions regarding missing inputs. Mammary removal of glutamate, isoleucine, lysine, phenylalanine, tyrosine, valine, glycerol, beta -hydroxybutyrate (BHBA), and acetate were predicted less accurately when simulations of the independent data set were conducted. Twenty-five percent of the observed variation in milk protein yields for the independent data set was explained by the model. Refitting parameters for removal of isoleucine, lysine, phenylalanine, tyrosine, valine, glycerol, BHBA, and acetate raised the variation explained to 43%. Sensitivity analysis indicated that milk protein synthesis was responsive to only the five EAA used in its determination, with sensitivity to any single EAA falling to zero as supply of the EAA exceeded protein synthetic needs. Similarly, milk protein synthesis was readily affected by parameters associated with removal and metabolism of the five EAA. Milk lactose was found to be sensitive to glucose input as well as to similar parameters and inputs as milk protein. It is concluded that representation of the milk protein synthesis process as a function of a single limiting EAA may not be adequate and might be better represented by simultaneous consideration of multiple EAA. Additional work on the description of energy metabolism is also suggested.

Amino Acids↗

PubMed1982

Correlates of dental anxiety in a university population.

The purpose of this study was to identify correlates of dental anxiety in university students. Dental anxiety was measured by means of the Corah Dental Anxiety Scale. Information about the students' dental attitudes, perceptions, and past dental experiences was collected by a written questionnaire administered to an approximately 13 percent random sample of all full-time students. The response rate was 27.3 percent (n = 846). The mean dental anxiety score for the entire study group was 8.77; mean scores for men (8.44) and women (9.10) were significantly different. Of the 18 independent variables studied, seven were found to be significantly associated with dental anxiety scores: sex, frequency of childhood visits to the dentist, childhood experience with dentists, frequency of mothers' visits to a dentist, perceived number of types of services required, symptoms as reason for last dental visit, and number of preventive actions taken prior day. As a group, the independent variables explained 22.8 percent of the observed variation in dental anxiety scores. When the amount of variation which was explained by each of the independent variables was considered separately four variables were found to be significant: childhood experience with dentists, gender, attitudes toward dentists, and number of preventive actions taken the prior day. Further studies are required to identify additional antecedents of dental anxiety in university students. These studies should focus on the ability of the antecedents to explain observed variation in anxiety levels.

Adult↗

PubMed1981

A genetic analysis of taste threshold for phenylthiocarbamide.

Taste threshold for phenylthiocarbamide (PTC) was measured in 393 offspring from the families of 85 monozygotic (MZ) twin pairs. PTC scores were bimodally distributed with modes at one and eight and the antimode at five. Because of the non-normality of the distribution, a jackknife procedure was used to obtain 95% confidence intervals for the estimates of genetic, maternal, and environmental parameters. Analyses which assumed no epistasis and which included additive genetic effects revealed that 37.9% of the observed variation in PTC threshold was due to additive genetic effects, 16.6% was due to dominance effects, 14.2% was due to maternal effects, 13.7% was due to a common sibship environment, and 17.6% was due to random environmental effects, yielding a broad sense heritability of 0.55 for the threshold ability to taste PTC. Analyses which did not include additive genetic effects revealed 26.6% of the observed variance was due to dominance effects, 23.6% to maternal effects, and 49.8% to environmental effects at the 0.67 confidence levels, but that environmental factors accounted for 72.4% and dominance effects for 23.6% of the observed variation at the 95% level.

Adolescent↗