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The effectiveness of standard care, early intervention, and occupational management in worker's compensation claims.

STUDY DESIGN: A retrospective and prospective cohort. OBJECTIVES: To compare the effectiveness of occupational intervention, early intervention, and standard care in the management of Worker's Compensation injury claims. SUMMARY OF BACKGROUND DATA: The current management of occupational back pain and work-related upper extremity disorders with either standard care or early intervention appears to be ineffective. METHODS: A retrospective cohort compared injury claim incidence, duration, and costs between one company with access to standard care and another similar company with access to early intervention. A prospective cohort looked at the effect of one company changing from standard care to occupational management in comparison with the control group with early intervention. Survival analysis was used to attempt to explain differences in injury claim duration. RESULTS: Standard care resulted in lower injury claim incidence, duration, and costs than early intervention, whereas occupational management resulted in lower injury claim incidence, duration, and costs than standard care. The covariates of physical therapist involvement, chiropractor involvement, injury severity, and relationship between Worker's Compensation and the employer were associated with delayed time to claim closure in the company with access to early intervention with the most important covariate being physical therapist involvement (hazard rate ratio 19.88, 95% confidence interval 7.95-39.77). Only the covariate of injury severity was associated with delayed time to claim closure in the company with access to occupational management (hazard rate ratio 1.67, 95% confidence interval 1.05-27.20). CONCLUSIONS: It is recommended that an occupational management approach, in comparison with standard care or early intervention, be considered for management of occupational injuries.

Accidents, Occupational↗

Radiation safety standards and their application: international policies and current issues.

This paper briefly describes the current policies of the United Nations Scientific Committee on the Effects of Atomic Radiation and the International Commission on Radiological Protection and how these policies are converted into international radiation safety standards by the International Atomic Energy Agency, which is the only global organization-within the United Nations family of international agencies-with a statutory mandate not only to establish such standards but also to provide for their application. It also summarizes the current status of the established corpus of such international standards, and of it foreseeable evolution, as well as of legally binding undertakings by countries around the world that are linked to these standards. Moreover, this paper also reviews some major current global issues related to the application of international standards, including the following: strengthening of national infrastructures for radiation safety, including technical cooperation programs for assisting developing countries; occupational radiation safety challenges, including the protection of pregnant workers and their unborn children, dealing with working environments with high natural radiation levels, and occupational attributability of health effects (probability of occupational causation); restricting discharges of radioactive substances into the environment: reviewing current international policies vis-a-vis the growing concern on the radiation protection of the "environment;" radiological protection of patients undergoing radiodiagnostic and radiotherapeutic procedures: the current International Action Plan; safety and security of radiation sources: post-11 September developments; preparedness and response to radiation emergencies: enhancing the international network; safe transport of radioactive materials: new apprehensions; safety of radioactive waste management: concerns and connections with radiation protection; and radioactive residues remaining after the termination of activities: radiation protection response to the forthcoming wave of decommissioning of installations with radioactive materials. The ultimate aim of this paper is to encourage information exchange, cooperation, and collaboration within the radiation protection professional community. In particular, the paper tries to facilitate consolidation of the growing international regime on radiation safety, including the expansion of legally binding undertakings by countries, the strengthening of the current corpus of international radiation safety standards, and the development of international provisions for ensuring the proper worldwide application of these standards, such as a system of international appraisals by peer review.

Government Agencies↗

Prediction of visual field defects on standard automated perimetry by screening C-20-1 frequency doubling technology perimetry.

PURPOSE: To determine if perimetric defects, initially seen with C-20-1 frequency doubling technology (FDT) in eyes with normal standard automated perimetry (SAP), will subsequently develop on standard automated perimetry. METHODS: Review of patients considered high-risk glaucoma suspects (GS) or with ocular hypertension (OHT), who underwent one C-20-1 FDT in 1997 or 1998. An abnormal frequency doubling technology was defined in two ways, as having either at least one, or at least two abnormal locations. An abnormal standard automated perimetry was defined as fulfilling two of three modified Anderson criteria for abnormality on two consecutive tests and at final standard automated perimetry. RESULTS: Of 63 eyes (50 patients), 18 (28.6%) had >or=1 FDT defects, and 12 (19.0%) had >or=2 defects. After follow-up of 62 +/- 26 months, an abnormal standard automated perimetry developed in 5 eyes (28%) with frequency doubling technology defects at 22 +/- 13 months (28% of eyes with >or=1 defect and 42% of eyes with >or=2 FDT defects), and in 4 of 45 eyes (9%) with normal frequency doubling technology at 32 +/- 30 months. Kaplan-Meier survival analysis revealed the risk of an abnormal standard automated perimetry at 5 years with or=1 defects, and >or=2 defects, was 10.3%, 11.8%, 30.6%, and 46.4% respectively (P = 0.060 for >or=1 defects compared with no defects; P = 0.002 for >or=2 defects compared with <or=1 defect). CONCLUSIONS: Abnormal results on C-20-1 frequency doubling technology perimetry predicted glaucomatous visual field loss on standard automated perimetry in some patients in this patient population, though a relatively high false positive rate was noted. Abnormality on C-20-1 frequency doubling technology warrants close observation, and further prospective evaluation is warranted.

Aged↗

Nasal provocation testing as an international standard for evaluation of allergic and nonallergic rhinitis.

Standardized nasal provocation testing (NPT) has been shown to be a safe and very useful tool in the diagnosis of allergic and nonallergic rhinitis. However, in the United States, its use has been mostly limited to scientific investigations, and it has not yet been widely accepted as a standard diagnostic procedure in clinical practice. NPT aims to identify and quantify the clinical relevance of inhalant allergens or occupational irritants. During NPT, nasal respiratory mucosa is exposed to an airborne substance suspected to cause symptoms in the respective individual. Clinical reactions are monitored in a controlled and standardized fashion. Nasal secretions, symptoms such as itching, sneezing and, most importantly, nasal obstruction are assessed as well as ocular, bronchial, cutaneous, and systemic reactions. To achieve objective data on changes in nasal airflow and patency after the challenge, anterior rhinomanometry and acoustic rhinometry have been included in the standard protocol of NPT. By monitoring changes of nasal airflow on one hand and of nasal geometry on the other hand, these methods display nasal function in a graphic way just as speech and pure tone audiometry do for auditory function. Also, by their objective nature, these methods offer a clear and internationally comparable standard. This review outlines a protocol for NPT and discusses practical applications and clinical indications. The use of rhinomanometry and acoustic rhinometry as objective diagnostic tools is emphasized. For the diagnosis of allergic and occupational rhinitis, standardized NPT should be regarded as an international diagnostic standard.

Allergens↗

Perceptions on the standardization of psychiatric work: development of a care pathway.

Policy development and practice for hospital care has shifted towards a more deterministic approach. Crucial within this development is the assumption that interventions can be standardized to fit within the confines of a practice framework. A system to deliver standardized approaches to care is a care pathway. A research study was carried out to determine how care could be standardized to fit within a care pathway for people diagnosed with schizophrenia. A range of interviews with the multidisciplinary team and observations of the working group process was the data collection technique. Analysis was driven by emergent themes across the data set. Clinicians expressed divergent views on the nature of standardized care for people with schizophrenia. Respondents also offered a deeper understanding of standardized care by arguing for a sense of flexibility to be built into care systems. Findings from this study have implications for the introduction of NICE core standards for people with schizophrenia. For example, clinicians may be so opposed to such structures as to work against them. By understanding different views on standardized care, it may ultimately support their introduction into practice.

Attitude of Health Personnel↗

Classification of small-for-gestational age births: weight-by-gestation standards of second birth conditional on the size of the first.

Percentiles of weight-by-gestational age were constructed for first and second births, based on linked sibship-data from the Medical Birth Registry of Norway. Standards were made for weight-by-gestational age of second births conditional on whether the first birth was small-for-gestational age (SGA) or large-for-gestational age (LGA). These standards were compared with the conventional, cross-sectional standard of all second births. The relevance of the conditional standards was assessed on the basis of perinatal mortality, using logistic regression analyses. When applying cross-sectional standards of second births, more than 30% of the births following a SGA first birth were classified as SGA, compared with only 1.7% following an LGA first births. The overall risk for a perinatal loss in second births following a SGA first birth was twice that among second births following a LGA first birth. When second births were themselves categorised as SGA or non-SGA using the cross-sectional standards, the mortality among the SGA second births was such that the risk was 4 to 5 times higher following LGA first births compared with SGA first births. When conditional standards were applied to define SGA among second births, the risk relation between the subgroups (defined by classification of first birth) corresponded to the observed overall risk pattern. An unconditional SGA classification conceals important differences between clinically distinct subgroups.

Birth Weight↗

Comparison of long-term monitoring and standard cystometry in chronic retention of urine.

Twenty-eight men with chronic retention of urine were investigated by means of a standard medium fill cystometrogram and by long-term monitoring of bladder pressure whilst the bladder filled naturally. Effective cystometric capacity was greater in each patient during standard cystometry (297 +/- 180 ml) than during long-term monitoring (99 +/- 100 ml; P less than 0.002). The incidence of detrusor instability was also greater during long-term monitoring than during standard cystometry (P less than 0.01). During filling, the detrusor pressure increased significantly both in standard cystometry (27.9 +/- 22.8 cmH2O; P less than 0.002) and in long-term monitoring (4.9 +/- 6.5 cmH2O; P less than 0.002). The detrusor pressure rise during filling was significantly greater during the standard cystometrogram than during long-term monitoring (P less than 0.002). Even when the detrusor pressure rise was corrected to take account of the different cystometric capacities this difference persisted (P less than 0.05). High end filling pressures are common in men with chronic retention investigated by means of a standard cystometrogram but are not observed during long-term monitoring. Such high pressures are probably due to the unphysiological rates of filling and the large volumes of fluid instilled during standard cystometry.

Aged↗

Comparison of bipolar transurethral resection of the prostate with standard transurethral prostatectomy: shorter stay, earlier catheter removal and fewer complications.

UNLABELLED: Authors from Detroit assess the use of the bipolar TURP against the monopolar technique; there were relatively few patients, reflecting the decreasing requirement for TURP in the USA. In addition, the amount of resected tissue was not particularly large, almost certainly a reflection of the decreasing size of resected prostatic tissue in that country. They found the bipolar TURP to have many advantages over standard monopolar TURP, and these are described. Acute urinary retention is a common urological emergency, and authors from London found that it had a measurable impact on the health-related quality of life of patients who develop this problem. They describe particularly how painful a condition it is, and that it had a significant economic burden. OBJECTIVE: To assess bipolar transurethral prostatectomy (TURP) using the Gyrus system (Gyrus Medical, Maple Grove, MD) compared with a standard monopolar TURP. PATIENTS AND METHODS: All 43 patients undergoing TURP from November 2000 to August 2002 were reviewed retrospectively; the 1.5-year observation period allowed for the detection of late complications. In all, 18 consecutive patients had standard and 25 had bipolar TURP. RESULTS: The resection was 18 g for standard and 15 g for the Gyrus TURP (part of the Gyrus chips are vaporized during resection). The Foley catheter was removed sooner (1.8 vs 3.2 days) and the hospital stay was less in the Gyrus group (1.2 vs 2.1 days). Acute complications occurred in a third of the standard group and four (16%) of the Gyrus group. Long-term complications were comparable, at two each in the standard and Gyrus groups. Four patients (15%) with small glands went home on the day of surgery, needing no bladder irrigation after Gyrus TURP. CONCLUSION: Few innovations in TURP technique have been described in the past few decades but comparing Gyrus to standard TURP showed that the former allows earlier removal of the urinary catheter and earlier discharge from hospital, while decreasing complications. The Gyrus system also has other benefits; it allows coagulation of tissue during resection, resulting in excellent intraoperative visualization, and normal saline is used as the irrigant fluid, reducing the potential for TUR syndrome. The shorter stay after Gyrus TURP can result in cost savings of up to $1200/patient/day at our institution.

Adult↗

Defining standard of care in the developing world: the intersection of international research ethics and health systems analysis.

In recent years there has been intense debate regarding the level of medical care provided to 'standard care' control groups in clinical trials in developing countries, particularly when the research sponsors come from wealthier countries. The debate revolves around the issue of how to define a standard of medical care in a country in which many people are not receiving the best methods of medical care available in other settings. In this paper, we argue that additional dimensions of the standard of care have been hitherto neglected, namely, the structure and efficiency of the national health system. The health system affects locally available medical care in two important ways: first, the system may be structured to provide different levels of care at different sites with referral mechanisms to direct patients to the appropriate level of care. Second, inefficiencies in this system may influence what care is available in a particular locale. As a result of these two factors locally available care cannot be equated with a national 'standard'. A reasonable approach is to define the national standard of care as the level of care that ought to be delivered under conditions of appropriate and efficient referral in a national system. This standard is the minimum level of care that ought to be provided to a control group. There may be additional moral arguments for higher levels of care in some circumstances. This health system analysis may be helpful to researchers and ethics committees in designing and reviewing research involving standard care control groups in developing country research.

Control Groups↗

Impact of mild to moderate hearing loss on mental status testing. Comparability of standard and written Mini-Mental State Examinations.

Mild to moderate hearing loss has been hypothesized to decrease performance on verbally-administered cognitive tests as an artifact of testing. To evaluate this hypothesis, we conducted a randomized trial of a written version of the Mini-Mental State Examination (MMSE), a cognitive screening instrument which, in its standard form, is primarily verbally administered. After baseline standard MMSE testing, 71 outpatients with Alzheimer's type dementia, 39 of whom (55%) had mild to moderate hearing deficits, and 32 of whom (45%) had normal hearing, were randomly assigned to receive either a written or standard MMSE. Hearing-impaired patients exhibited lower standard MMSE scores than hearing-unimpaired patients at baseline (P = .005). Contrary to expectation, however, on experimental administration, written MMSE scores were somewhat lower than standard MMSE scores in hearing-impaired patients (P not significant). Furthermore, written MMSE scores were slightly higher than standard MMSE scores in hearing-unimpaired patients (P not significant). These results suggest that the diminished cognitive performance associated with mild to moderate hearing loss is not necessarily an artifact of cognitive testing. In addition, these results provide preliminary evidence that a written MMSE is comparable to the standard MMSE and, thus, deserves further consideration for cognitive screening of profoundly hearing-impaired individuals.

Aged↗

A comparison of the Synthes 4.5-mm cannulated screw and the Synthes 4.5-mm standard cortex screw systems in equine bone.

OBJECTIVE: To determine risk of failure of the Synthes 4.5-mm cannulated screw system instrumentation in equine bone and to compare its application with the Synthes 4.5-mm standard cortex screw system. STUDY DESIGN: The maximum insertion torque of the cannulated and standard cortex screw systems were compared with the ultimate torsional strengths of the equipment. Pullout strength and ultimate tensile load of cannulated and standard cortex screws were also determined. SAMPLE POPULATION: Paired equine cadaver third metacarpal and third carpal bones. METHODS: Maximum insertion torque and ultimate torsional strengths were determined by using an axial-torsional, servohydraulic materials testing system and a hand-held torquometer. Pullout tests were performed by using a servohydraulic materials testing system. RESULTS: Maximum insertion torque of all cannulated instrumentation was less than ultimate torsional strength at all locations (P < .05). Maximum insertion torques of cannulated taps and screws were greater than for standard taps and screws in the third carpal bone (P < .002). Pullout strength of the cannulated screws was less than the standard cortex screws at all sites (P < .001). Cannulated screws broke before bone failure in all but one bone specimen. CONCLUSIONS: The risk of cannulated instrument or screw failure during insertion into bone is theoretically low. The relatively low pullout strength of the cannulated screws implies that the interfragmentary compression achievable is likely to be less than with standard cortex screws. CLINICAL RELEVANCE: The relatively low pullout strength of the cannulated screw suggests that its risk of failure during fracture repair is greater than with the standard cortex screw.

Animals↗

Predicting EPA's forthcoming CO standards in light of new clinical evidence.

For the past several years, the EPA has been monitoring clinical studies on the adverse health effects of heart patients' exposure to carbon monoxide. This paper examines the impact of three such studies (including the multi-center CO study organized by the Health Effects Institute) on the forthcoming EPA standards for carbon monoxide. Eleven peer-nominated specialists with expertise in environmental science and public policy were interviewed according to a specific protocol. Overall, the experts felt that the HEI study would receive greater weight than the other two studies in the regulatory process for a variety of technical reasons. Weighting each expert opinion equally, we conclude that there is about a 0.69 probability that the CO standards will be retained at their present levels, a 0.28 probability that the standards will be tightened, and a 0.03 probability that the standards will be relaxed. When asked to imagine that the HEI data were never collected and then asked to reassess their probability judgments, the mean probability judgment that the standards will be relaxed rose to 0.11, while the mean probability judgment that the standards will be tightened fell to 0.20. A modest degree of variability in expert opinion is reported in the paper. While the HEI study may receive relatively great weight in the regulatory process, it increases only slightly the probability that EPA's CO standards will be changed.

Angina Pectoris↗

WHO Child Growth Standards based on length/height, weight and age.

AIM: To describe the methods used to construct the WHO Child Growth Standards based on length/height, weight and age, and to present resulting growth charts. METHODS: The WHO Child Growth Standards were derived from an international sample of healthy breastfed infants and young children raised in environments that do not constrain growth. Rigorous methods of data collection and standardized procedures across study sites yielded very high-quality data. The generation of the standards followed methodical, state-of-the-art statistical methodologies. The Box-Cox power exponential (BCPE) method, with curve smoothing by cubic splines, was used to construct the curves. The BCPE accommodates various kinds of distributions, from normal to skewed or kurtotic, as necessary. A set of diagnostic tools was used to detect possible biases in estimated percentiles or z-score curves. RESULTS: There was wide variability in the degrees of freedom required for the cubic splines to achieve the best model. Except for length/height-for-age, which followed a normal distribution, all other standards needed to model skewness but not kurtosis. Length-for-age and height-for-age standards were constructed by fitting a unique model that reflected the 0.7-cm average difference between these two measurements. The concordance between smoothed percentile curves and empirical percentiles was excellent and free of bias. Percentiles and z-score curves for boys and girls aged 0-60 mo were generated for weight-for-age, length/height-for-age, weight-for-length/height (45 to 110 cm and 65 to 120 cm, respectively) and body mass index-for-age. CONCLUSION: The WHO Child Growth Standards depict normal growth under optimal environmental conditions and can be used to assess children everywhere, regardless of ethnicity, socio-economic status and type of feeding.

Body Height↗

Comprehensive evaluation of a commercial macro Monte Carlo electron dose calculation implementation using a standard verification data set.

A commercial electron dose calculation software implementation based on the macro Monte Carlo algorithm has recently been introduced. We have evaluated the performance of the system using a standard verification data set comprised of two-dimensional (2D) dose distributions in the transverse plane of a 15 X 15 cm2 field. The standard data set was comprised of measurements performed for combinations of 9-MeV and 20-MeV beam energies and five phantom geometries. The phantom geometries included bone and air heterogeneities, and irregular surface contours. The standard verification data included a subset of the data needed to commission the dose calculation. Additional required data were obtained from a dosimetrically equivalent machine. In addition, we performed 2D dose measurements in a water phantom for the standard field sizes, a 4 cm X 4 cm field, a 3 cm diameter circle, and a 5 cm X 13 cm triangle for the 6-, 9-, 12-, 15-, and 18-MeV energies of a Clinac 21EX. Output factors were also measured. Synthetic CT images and structure contours duplicating the measurement configurations were generated and transferred to the treatment planning system. Calculations for the standard verification data set were performed over the range of each of the algorithm parameters: statistical precision, grid-spacing, and smoothing. Dose difference and distance-to-agreement were computed for the calculation points. We found that the best results were obtained for the highest statistical precision, for the smallest grid spacing, and for smoothed dose distributions. Calculations for the 21EX data were performed using parameters that the evaluation of the standard verification data suggested would produce clinically acceptable results. The dose difference and distance-to-agreement were similar to that observed for the standard verification data set except for the portion of the triangle field narrower than 3 cm for the 6- and 9-MeV electron beams. The output agreed with measurements to within 2%, with the exception of the 3-cm diameter circle and the triangle for 6 MeV, which were within 5%. We conclude that clinically acceptable results may be obtained using a grid spacing that is no larger than approximately one-tenth of the distal falloff distance of the electron depth dose curve (depth from 80% to 20% of the maximum dose) and small relative to the size of heterogeneities. For judicious choices of parameters, dose calculations agree with measurements to better than 3% dose difference and 3-mm distance-to-agreement for fields with dimensions no less than about 3 cm.

Journal Article↗

Evaluation of a new set of calibration standards for the measurement of fat content via DPA and DXA.

A simulation study was performed to evaluate a new set of calibration standards for estimating the fat content of the body via dual-photon absorptiometry (DPA) and dual-energy x-ray absorptiometry (DXA). The standards, proposed by Nord and Payne [presented at the 2nd meeting of The Bath Conference on Bone Mineral Measurement (1990)] consist of stearic acid (100% fat) and 0.6% NaCl in water (100% lean). They were compared with other standards consisting of average composition adipose/muscle tissues and fatty adipose/lean muscle tissues. Source and detector properties of a Gd-153 DPA system and three commercial DXA systems were modeled. For each system and calibration set, rms errors in the calculated fat contents of simulated tissues having fat mass percentages that ranged from about 4%-44% and thicknesses that ranged from 5-20 cm were determined. Beam hardening errors for the systems were evaluated as was a calibration technique employed by one of the manufacturers to correct for such errors. In general, the smallest rms errors (2% or less when the calibration standards and tissues were of equal thickness) were obtained with the average adipose/muscle standards. Equivalent results were obtained with standards consisting of stearic acid and 0.8% NaCl. The latter is a higher salt content than proposed by Nord and Payne and results from differences in the x-ray attenuation coefficients that were employed in calculating the fat equivalence of water. Other, more convenient standards, such as lucite and water may be employed by using appropriate fat equivalences (approximately 69% for lucite and approximately 10% for water). Beam hardening errors for the DXA systems are considerable, and the simulated correction technique was shown to be effective.

Absorptiometry, Photon↗

History, current status, and trends of radiation protection standards.

Quantitative standards for protection against exposure to ionizing radiation were first formulated in the 1930s. Since that time, standards have been restated periodically in different radiation units and conceptual frameworks that reflect improved understanding of the biological effects of radiation interactions and their consequences for human health. In the 1970s the expression of protection standards shifted from a dose- to a risk-based approach, with dose limits established to yield risks to radiation workers comparable with those for workers in other "safe" industries. Over the years, radiation protection standards have exhibited a downward trend to more rigorous limits that require increased commitments of personnel and resources for their enforcement. There are several reasons for this trend, including increased recognition of the long-term health effects of radiation, improved protection measures that permit radiation use at lower levels of exposure, growing numbers of persons exposed occupationally to radiation, and probably a greater intolerance to involuntary risks in society, with radiation targeted as a highly visible source of involuntary risks in the form of nuclear power plants and radioactive waste sites. In the past few years, reports of the Radiation Effects Research Foundation, United Nations Scientific Committee on the Effects of Atomic Radiation, and the National Research Council of the U.S. National Academy of Sciences have presented increased risk estimates for radiation exposure as a consequence of ongoing epidemiological analyses of human populations exposed to ionizing radiation. These risk estimates have enhanced public concern about radiation exposure and set the stage for discussions about the desirability of further reductions in exposure standards for radiation workers and members of the public. Such reductions would directly affect the professional activities, educational responsibilities, and administrative burdens of most medical and health physicists. These persons should understand the process of deriving risk estimates from epidemiological data, the factors that influence the risk estimates, how risk estimates are integrated into radiation protection standards, and the possible impact of more rigorous standards on the use of radiation in medicine.

Biophysics↗

An acoustic description of the vowels of Northern and Southern Standard Dutch.

A database is presented of measurements of the fundamental frequency, the frequencies of the first three formants, and the duration of the 15 vowels of Standard Dutch as spoken in the Netherlands (Northern Standard Dutch) and in Belgium (Southern Standard Dutch). The speech material consisted of read monosyllabic utterances in a neutral consonantal context (i.e., /sVs/). Recordings were made for 20 female talkers and 20 male talkers, who were stratified for the factors age, gender, and region. Of the 40 talkers, 20 spoke Northern Standard Dutch and 20 spoke Southern Standard Dutch. The results indicated that the nine monophthongal Dutch vowels /a [see symbol in text] epsilon i I [see symbol in text] u y Y/ can be separated fairly well given their steady-state characteristics, while the long mid vowels /e o ø/ and three diphthongal vowels /epsilon I [see symbol in text]u oey/ also require information about their dynamic characteristics. The analysis of the formant values indicated that Northern Standard Dutch and Southern Standard Dutch differ little in the formant frequencies at steady-state for the nine monophthongal vowels. Larger differences between these two language varieties were found for the dynamic specifications of the three long mid vowels, and, to a lesser extent, of the three diphthongal vowels.

Adult↗

Serological studies of actionomyces israelii by crossed immunoelectrophoresis: standard antigen-antibody system for A. israelii.

Standard preparations of crude cytoplasmic and whole cell-associated antigen mixtures of Actinomyces israelii were analyzed by crossed immunoelectrophoresis (CIE), with a standard polyvalent antiserum comprising purified and concentrated immunoglobulin G antibodies to formolized whole cells of A. israelii serotypes 1 and 2. The standard antigens provided four antigen-antibody systems for A. israelii. The immunoprecipitation patterns of the system were compared, and the immunochemical characteristics of individual precipitates were analyzed. Each system contained specific precipitates, but also one or two precipitates which were immunochemically identical to precipitates of the other systems. The standard system for A. israelii based on cytoplasmic antigens was best reproducible and revealed the highest number of immunoprecipitates. These precipitates possessed immunochemical properties which made them suitable for CIE studies. The cytoplasmic antigen mixture of A. israelii was, therefore, adopted as the most suitable for further development of a crossed immunoelectrophoretic system for A. israelii. In subsequent assays the cytoplasmic antigen mixture was raised in rabbit against cell lysates of A. israelii, serotypes 1 and 2. A standard antigen-antibody system for A. israelii was obtained which revealed an immunoprecipitation pattern of 10 distinguishable precipitates. The resolving power and separation by CIE of this standard system for A. israelii was compared with that of crossed immunoelectrofocusing. The results suggest that these methods supplement each other. Crossed immunoelectrofocusing appeared to be a useful tool for separation of specific components of the protein-antigen complex of A. israelii for analytic serology. The CIE in conjunction with a standard reference antigen-antibody system for A. israelii based on cytoplasmic antigens offers great potentialities in diagnostic A. israelii serology.

Actinomyces↗