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Signal detection procedures were used to measure subjects' ability to detect errors in performance as they tried to hit a target in a ballistic motor task, since current methods were found to have several important shortcomings. Two tasks were used; one involved moving a slide 24.1 cm in 150 msec (temporal target), and the other involved rolling a ball at a visible target (spatial target). Subjects in both tasks were poor at detecting errors. Variability in the perceptual processes, measured by signal detection proceudres, was found to be about twice as much as that in the motor processes, measured by calculating variable error. This finding was inconsistent with a strictly closed-loop model of motor skills. Signal detection theory was also able to fill a gap in present theories of motor learning by explaining why some of the subjects in this experiment were able to detect errors better in the absence of knowledge of results.
Cryptosporidium parvum is a ubiquitous enteric parasite that infects a diverse range of vertebrate species. The detection of C. parvum can be confounded when oocysts are intermittently shed below an assay's limit of detection, yielding a false-negative result. We therefore investigated the utility of Cryptosporidium parvum virus 1 (CSpV1), a putative symbiont of Cryptosporidium parvum, as a surrogate target for detecting the parasite in bovine calves. Using real-time polymerase chain reaction (qPCR), we tested 422 samples for Cryptosporidium spp., C. parvum-associated targets, and CSpV1. Among the 189 samples positive for at least one target, CSpV1 was detected in 24 (12.70%) samples without concurrent detection of Cryptosporidium. Additionally, we analyzed CSpV1 genomic sequences to ascertain its value as an epidemiological biomarker. Evaluation of dsRNA1 amino acid sequences identified country-associated patterns, suggesting potential utility for geographic distribution analyses. These findings suggest that CSpV1 may serve as a biological signature of C. parvum and support further investigation into its usefulness as an adjunct molecular target.
The heat-stable enterotoxin (ST) of Escherichia coli can be detected by infant mouse or dog intestinal loop tests. These tests differ in that the dog assay uses concentrated culture supernatants and is based on measurements of net intestinal absorption, whereas the mouse test uses unconcentrated supernatants and depends on gross fluid accumulation. To compare the relative sensitivities of these assays, culture supernatants of randomly selected E. coli isolates from 34 Bangalee diarrhea patients were tested for ST in dog loops and infant mice. Supernatants were also tested for heat-labile enterotoxin (LT) in dog loops, Y-1 adrenal cells, and Chinese hamster ovary cells. E. coli supernatants that produced positive responses for both ST and LT in the dog loop assay (ST+/LT+) also produced positive responses when tested for ST in infant mice and for LT in cell lines. Supernatants of strains negative for ST and LT in dog loop (ST-/LT) were also negative in other assays. Of 10 strains positive for just ST in the dog loop test (ST+/LT-), only 5 were ST positive in the standard infant mouse test. Supernatants of the other five strains (dog loop positive, mouse test negative) were then concentrated 100-fold and retested in mice. Three of these five gave consistently positive results after concentration, and two were only intermittently positive. Concentrated supernatants of negative control strains (ST-/LT-) were all negative in mice. The dog assay detects more strains producing ST than the infant mouse test. The infant mouse test, which detects only gross fluid accumulation, failed to detect approximately half of the 10 strains which produced ST alone (ST+/LT-; P = 0.025). Concentrating supernatants for the mouse assay increases sensitivity for detection of ST, but certain E. coli strains produce a variety of ST to which infant mice do not respond.
In 40 known carriers of the gene for Duchenne muscular dystrophy (mean age 38 years) the detection-rate with a standard assay of serum-creatine-kinase was 53%. In 52 daughters of known carriers (mean age 16 years) the detection-rate was 45% after correction of age. This implies a much higher detection-rate (about 90%) in young carriers and suggests that discrimination between carriers and noncarriers may best be achieved by testing in childhood.
A method for the detection of 3-hydroxy dodecanoic acid at low picogram levels is described. The procedure involves preparation of a heptafluorobutryl derivative of the butyl ester of the fatty acid and its detection by gas-liquid chromatography using an electron capture detector. The method was adapted for use with biological specimens. Potential of the method for screening for gonococcal infection is discussed. Limitations of the method are that about 105 Neisseria gonorrhoeae cells are required for detection and that interfering substances are a major problem working at maximum sensitivity of the electron capture detector necessitating complex purification procedures. The method eliminates the need to maintain the viability of cells in specimens, thus facilitating collection and transport of specimens.
In the territory of 5 anti-TBC dispensaries in the area of Bucharest 2 circumscriptions have been selected at random in which radiophotographic detection was to be carried out integrally and 2 other circumscriptions were selected for the investigation of groups at high risk of developing tuberculosis. All the new cases of active pulmonary tuberculosis that have been recorded, through all the methods in these 20 circumscriptions in 1973 were analized retrospectively and the reasons appeared that had determined their existence was mentioned or was ommitted on the occasion of previous investigations. These reasons were correlated with the data concerning the method for detection that had been employed, according to the indications of the tuberculosis dispensaries. In view of the evaluation of the degree of real covering of the population in integral rf investigations, the team of the Institute of Phtysiology investigated representative lots of population from each dispensary and checked the catagraphy of the population in the field, house-by-house. It was noted that 20--21% of the subjects that had been programmed for the integral rf examination (according to catagraphic criteria) were absent when the checking in the field, that should have been programmed, were not included in the catagraphy. On the basis of this study the methodology for radiophotographic detection for groups with risk of developing tuberculosis was established.
Data are reported for four race-sex and three age subgroups of the Hypertension Detection and Follow-up Program (HDFP). Throughout the HDFP trial, for black men, black women, white men, and white women and for persons aged 30 to 49, 50 to 59, and 60 to 69 years at entry, control of blood pressure was consistently better for Stepped Care (SC) than Referred Care (RC) participants. This difference in degree of control was least for white women; it was less for whites than for blacks of the same sex. For white men, black men, and black women and for age subgroups 50 to 59 and 60 to 69 years, five-year all-cause death rates were substantially lower--by 15% to 28%--for the SC subgroups compared to the RC subgroups.
An improved method is described for direct localization of human serum proteins in polyacrylamide gel with simultaneous determination of their isoelectric points (pI). The technique employs isoelectric focusing in thin-layer polyacrylamide gels to separate the serum proteins and the pH gradient is read at 4 degrees C with a dual-membrane surface microelectrode. Subsequently, the desired proteins are localized by immunofixation in the gel or by immunofixation-printing onto cellulose acetate strips soaked in specific antiserum. No sectioning of the electrofocused gel is necessary, and the entire technique can be completed in less than 14 h. When this method is applied to the detection of the genetic variants of alpha-1-antitrypsin (alpha-1-protease inhibitor) (A1Pi system), the results indicate that it can be used to specifically localize serum proteins whose pI's differ by as little as 0.01 pH units. The resolution afforded is especially evident in the analysis of A1Pi M variants.
The R-index approach to the signal-detection P(A) index of sensitivity was used to measure taste sensitivity to NaCl solutions. The R-index is the predicted probability of the correct choice of a signal, for a given signal-noise pair. For flow-wise and sipwise presentation, R-indices did not fluctuate significantly, provided subjects could not see the stimuli yet to be presented, indicating a lack of systematic sensitivity drift. The simultaneous measurement of more than one signal strength with reference to a common noise stimulus was seen to be a viable and sensitive procedure. Comparison of flow-wise and sipwise presentation of stimuli using R-indices, indicated that the former elicited greater subject sensitivity to NaCl taste.
Modulation threshold, that is, the modulation depth required to discriminate a sample of amplitude-modulated (AM) noise from a sample of unmodulated noise, was measured as a function of modulation rate (16--320 Hz), modulator waveform (sine or square), and the bandwidth of the AM noise (0.5--8.0 kHz). Modulation threshold increases monotonically with modulation rate, sine-wave thresholds are greater than square-wave thresholds, and threshold rises as the bandwith of the AM stimulus decreases. These effects all support the use of some form of energy detection model to explain modulation threshold. The modulation thresholds were compared with pitch thresholds gathered under precisely the same conditions. Pitch threshold or, alternatively, rate threshold was taken to be the modulation depth required to decide which of two samples had the higher modulation; the rate difference was 20%--just over three semitones. In the region above about 70 Hz, rate threshold is essentially a constant multiple of modulation threshold, indicating that the primary constraint on rate threshold is the audibility of the modulation. Below 70 Hz, rate and modulation threshold diverge; it is argued that the limit on rate threshold in this region is probably the length of the correlation required to extract the periodicity.
The Hypertension Detection and Follow-up Program (HDFP), in a community-based, randomized controlled trial involving 10,940 persons with high blood pressure (BP), compared the effects on five-year mortality of a systematic antihypertensive treatment program (Stepped Care [SC]) and referral to community medical therapy (Referred Care [RC]). Participants, recruited by population-based screening of 158,906 people aged 30 to 69 years in 14 communities througout the United States, were randomly assigned to SC or RC groups within each center and by entry diastolic blood pressure (DBP) (90 to 104, 105 to 114, and 115 + mm Hg). Over the five years of the study, more than two thirds of the SC participants continued to receive medication, and more than 50% achieved BP levels within the normotensive range, at or below the HDFP goal for DBP. Controls of BP was consistently better for the SC than for the RC group. Five-year mortality from all causes was 17% lower for the SC group compared to the RC group (6.4 vs 7.7 per 100, P less than .01) and 20% lower for the SC subgroup with entry DBP of 90 to 104 mm Hg compared to the corresponding RC subgroup (5.9 vs 7.4 per 100, P less than .01). These findings of the HDFP indicate that the systematic effective management of hypertension has a great potential for reducing mortality for the large numbers of people with high BP in the population, including those with "mild" hypertension.
It is presented a autoradiographic method for microscopical detection of 3H-choline chloride activity after intraventricular application in freeze-dried and paraffin-embedded brain sections. The 10 micrometer thick sections are treated with diethyl ether and than exposed during 90 days above calcium chloride at 4 degree C using the sandwich technique (with stripping film). After separate film explanation and section staining the film and the brain sections are mounted together.
In the German Democratic Republic (GDR), annual mass roentgenographic screening of the chest was introduced twenty years ago. To ascertain its value in the detection of lung cancer, data were collected about treatment results at the country's main chest clinics. The study cover 13,283 operations and 10,838 resections, accounting for nearly 90% of all patients with lung cancer treated surgically in the GDR from 1949-1974. From 1965 to 1968, the five-year survival was more favorable in patients who were screened than in those who were diagnosed after clinical symptoms had appeared (36% for the former, 29% for the latter). For improvement of overall results, we recommend differentiated regular chest roentgenographic screening of men 40 to 70 years of age, individualized on the basis of tobacco usage, and full exploitation of all diagnostic and surgical tools now available.
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Extracts of 3 soya bean preparations, used commercially in certain countries to replace part of the meat in popular meat products, were made by treatment with (i) sodium dodecyl sulphate, (ii) Triton-X100 or (iii) n-Butanol. Similar extracts were made from beef and pork. All extracts were examined by electrophoretic and immunological techniques. Stained polyacrylamide gels revealed distinctive protein bands after electrophoresis. The migration rates of corresponding bands differed between beef and pork extracts. However, the migration rates of vegetable bands revealed certain similarities, but differed very greatly from those of animal origin. Characteristic fast-migrating S-bands were distinguishable only in extracts of vegetable protein. Immunodiffusion tests, using antisera produced in rabbits against each extract, revealed varying degrees of similarity between extracts of vegetable origin, but the antisera were specific for either vegetable or animal protein.
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