Recombinant Cysteine Proteinase B from Leishmania braziliensis and Its Domains: Promising Antigens for Serodiagnosis of Cutaneous and Visceral Leishmaniasis in Dogs.

Leishmaniasis represents a group of parasitic diseases caused by a protozoan of the genus Leishmania and is widely distributed in tropical and subtropical regions. Leishmaniasis is one of the major tropical neglected diseases, with 1.5 to 2 million new cases occurring annually. Diagnosis remains a challenge despite advances in parasitological, serological, and molecular methods. Dogs are an important host for the parasite and develop both visceral and cutaneous lesions. Our goal was to contribute to the diagnosis of canine cutaneous leishmaniasis (CL) and visceral leishmaniasis (VL) using the recombinant cysteine proteinase B (F-CPB) from Leishmania braziliensis and its N- and C-terminal domains (N-CPB and C-CPB) as antigens in an enzyme-linked immunosorbent assay (ELISA). Sera from dogs from Northwest Argentina diagnosed with CL were tested by ELISA against a supernatant of L. braziliensis lysate, the F-CPB protein, and its domains. We found values of sensitivity (Se) of 90.7%, 94.4%, and 94.3% and specificity (Sp) of 95.5%, 90.9%, and 91.3% for F-CPB and its N- and C-terminal domains, respectively. In sera from dogs diagnosed with VL from Northeast Argentina, we found Se of 93.3%, 73.3%, and 66.7% and Sp of 92.3%, 76.9%, and 88.5% for F-CPB and its N- and C-terminal domains, respectively. These results support CPB as a relevant antigen for canine leishmaniasis diagnosis in its different clinical presentations. More interestingly, the amino acid sequence of CPB showed high percentages of identity in several Leishmania species, suggesting that the CPB from L. braziliensis qualifies as a good antigen for the diagnosis of leishmaniasis caused by different species.

Serum sCD26 for colorectal cancer screening in family-risk individuals: comparison with faecal immunochemical test.

BACKGROUND: The development of specific screening programs for individuals with a family history of colorectal cancer (CRC) is a priority. This study evaluates the diagnostic performance of serum soluble CD26 (sCD26) in family-risk individuals and compares this marker with the faecal immunochemical test for the detection of advanced neoplasia (AN) (CRC or advanced adenomas; AA). METHODS: Five hundred and sixteen asymptomatic individuals with at least one first-degree relative with CRC were included. Serum sCD26 was measured in all the individuals who also underwent a colonoscopy (53 AA and four cancer cases were found) and a faecal immunochemical test. RESULTS: Setting specificity to 90% and 95%, respectively, sCD26 showed a sensitivity of 39.6% and 28.3% for AA, and of 42.1% and 28.1% for AN. The combination of sCD26 and the faecal test detected AA and AN with a 52.8% and 56.1% sensitivity, corresponding to 93.5% specificity. CONCLUSIONS: The combination of serum sCD26 and the faecal blood test could result a valuable strategy for detecting AN in familial-risk CRC screening.

Redetermination of 1-cyclo-hexyl-3-(2-furo-yl)thio-urea.

The title compound, C(12)H(16)N(2)O(2)S, was synthesized from furoyl isothio-cyanate and cyclo-hexyl-amine in dry acetone, and the crystal structure redetermined. The thio-urea group is in the thio-amide form. The structure [Otazo-Sánchez et al. (2001 ▶). J. Chem. Soc. Perkin Trans. 2, pp. 2211-2218] has been redetermined in order to establish the intra- and inter-molecular inter-actions. The trans-cis geometry of the thio-urea group is stabilized by intra-molecular hydrogen bonding between the carbonyl and cis-thio-amide groups, resulting in a pseudo-S(6) planar ring which makes a dihedral angle of 3.24 (6)° with the 2-furoyl group and a torsion angle of -84.3 (2)° with the cyclo-hexyl group. There is also an intra-molecular hydrogen bond between the furan O atom and the other thio-amide H atom. In the crystal structure, mol-ecules are linked by inter-molecular N-H⋯O hydrogen bonds, forming chains along [010].

Biochemical and haematological measurements in beef cattle in Mendoza plain rangelands (Argentina).

Biochemical and haematological measurements were used to identify constraints on productivity in beef cattle. One hundred and twelve Aberdeen Angus and Criollo Argentino females including lactating cows, dry non-pregnant cows and heifers were selected. Blood samples were taken in the middle of summer and autumn. Serum was analysed for haemoglobin, PCV, glucose, albumin, urea, creatinine, Ca, P, Mg, Fe, Cu, ALP, AST, ALT, CK, LDH, Cl-, Na and K content. Globulin was calculated by taking the difference between total protein and albumin. Percentages of all cattle that had metabolite levels outside reference ranges were: 15% (glucose), 8% (globulin), 5% (urea), 96% (Ca), 50% (P), 12% (Mg), 20% (Na), 5% (K), 24% (Cl), 18% (Fe), 5% (Cu) and 85% (CK). These results indicate with some certainty that dietary protein was not limiting. Body condition score loss was detected only in lactating cows. There were a few animals that could have presented chronic inflammatory disease. Phosphorus could be an important potential constraint on fertility, although the presence of symptoms of hypophosphataemia was not observed. The study also demonstrates the absence of anaemia or liver disease. Breed, seasonal and physiological state differences in some blood metabolites could be attributed to one or more of the following factors: chemical composition of the feed ingested, environmental temperature, nutrient content of the forage, animal age and cattle foraging experience. The study provides a basis for implementing helpful adjustments in current cattle management practices so as to alleviate the constraints on productivity, provided that these practices are profitable.

Counterphase dichoptic flicker is seen as its own second harmonic.

If a patternless field is modulated sinusoidally in time so that the luminance change in one eye is in counterphase to that in the other, the resulting flicker appears faster than if the modulation to both eyes has the same phase. If observers set the frequency and the amplitude of a comparison in-phase field so that it matches a neighbouring counterphase field, modulated at, say, 2.5 x its threshold, they set the frequency to twice the counterphase frequency, and the amplitude to a value that is, for a given frequency, a constant ratio of the modulation of the counterphase field. Counterphase stimulation thus appears to cause an internal second-harmonic signal. However, it is not possible to cancel this by adding a second harmonic component to the stimulus.

Improved color fundamentals offer a new view on photometric additivity.

New action spectra are derived for the foveal cones on the basis of three assumptions: (1) the Stiles-Burch (1959) colorimetric data are better than CIE 1931; (2) the long wavelength flanks of the dichromatic luminosity functions offer better anchorage than the confusion loci; and (3) the relative mutual heights per receptor can be derived from the Bezold-Brücke effect. Since these assumptions do not include photometric data, we could at the end ask how L lambda, M lambda and S lambda combine to V lambda. The best answer appeared to be V lambda = 0.68 L lambda + 0.34 M lambda -0.02 S lambda, reflecting both relative receptor population densities and a negative input of the S-system to luminance.

Undergraduate teaching of oncology in Argentina.

Cancer is a public health problem in Argentina, and the role of the country's physicians in the fight against this disease is very important. Whether they are general physicians or specialists, including clinical oncologists, they must have basic knowledge and permanent updating in oncology. Unfortunately, the teaching of oncology is deficient in this country, the deficiencies being already noticeable at the undergraduate level where the teaching is incomplete and dispersed. In order to ascertain the level of oncologic information which medical students about to graduate had acquired, 15-hour courses were organized in 1983 to 1984 for students of the Universities of Buenos Aires, La Plata, and Del Salvador. The participants had to fill in a questionnaire of 50 questions of increasing complexity before and after the course. The comparison of both inquiries clearly showed the usefulness of the course, particularly regarding cancer control, early diagnosis, treatment, and curability. The overall error decreased by 50% after the course. However, some erroneous ideas still existed and it became evident that certain of the subjects must be studied in greater depth.

Tyndall's paradox of hue discrimination.

We confirm a remarkable but forgotten property of human color vision that was described over 50 years ago by Tyndall [J. Opt. Soc. Am 23, 12 (1933)]: if wavelength discrimination is measured in the region of 455 nm, the sensitivity of the eye improves when a large fraction of the monochromatic light in each half of the matching field is replaced by white light that is common to the two halves. We demonstrate that a similar facilitation also occurs when the shortwave monochromatic components are held constant in luminance and a long-wave desaturant of increasing luminance is added to the shortwave discrimanda. We relate these phenomena to the properties of postreceptoral visual channels.

Interindividual receptor variability of normal colour observers: analysis of the 2-deg Stiles and Burch data.

Examination of the interobserver variability among the ten observers of the 2-deg Stiles and Burch colorimetric study reveals an interesting pattern: the chromaticities of the matches made by different normal subjects fall approximately on straight lines and these lines appear to converge. Because of a geometric relationship that holds between the normal, anomalous, and dichromatic colour spaces, it can be argued that part of the variability must be due to actual differences in the shape or spectral position of the receptor sensitivities of different normal observers.

Evoked potential latencies as a function of contrast: a system analytical approach.

That the latency of the pattern evoked potential (EP) increases as the stimulus contrast decreases can be understood as the result of, first, a low-pass filtering process of the (contrast) signal followed by, second, and nonlinear 'threshold' stage. We show here that by using this simple concept it is possible to estimate the shape of the 'unit step' response of the low-pass filter with the latency vs. contrast data. We show also that the step responses calculated from several subjects are in reasonable agreement if they are normalized with using the subjects' own contrast thresholds. Within experimental error, the response of a filter consisting of four low-pass first-order stages with a 10.5 Hz cut-off frequency gives a reasonable fit to our own data and to that of one other study (Musselwhite and Jeffreys, 1982).

Colour and photosensitive epilepsy.

Red-coloured flicker is claimed to be more epileptogenic than white or that of other colours matched for subjective intensity. A feature of the colour opponent system is that the response of luminosity-sensitive cortical units to stimulation of ganglion cells of a particular spectral sensitivity is reduced when cells of other sensitivities are simultaneously stimulated. We hypothesized that the apparent effect of colour on photosensitivity was not a property of red light per se but arose simply from the fact that, with commercially available filters a light can be provided to stimulate only red sensitive cones, but owing to the overlap of the absorption spectra of the visual pigments it is difficult to stimulate only green or blue sensitive cones. Such stimulation of a single cone population can be achieved by the 'silent substitution method' which has been used for evoked response studies. In 12 photosensitive epileptic patients we find that, using stimulus intensities (less than 20 nits) at which white flicker is without effect, stimulation of either red or green cones by the silent substitution method may produce epileptiform discharges, there being a slight (and not significant) excess of patients showing a greater sensitivity for green than for red cone stimulation. The findings are considered to support the hypothesis set out above.

The "silent substitution" method in visual research.

The "silent substitution" method, which has become well-known mostly through the work of Rushton and his collaborators, can be traced back to experiments performed by M. Ishihara under Exner's supervision at the beginning of the century. Rushton provided a theoretical framework for the method with the enunciation of his "principle of univariance". In this paper we show how the "silent substitution" concept can be further generalized to any arbitrary number of photoreceptor classes by making use of well-established concepts of colorimetry. With this approach, which we have called "spectral compensation", one also gains a better insight into the possibilities and shortcomings of the technique. To illustrate this, we apply our approach to examine a number of published studies where use has been made of "silent substitution", with particular emphasis on the work of W. A. H. Rushton.