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Biomedical subjects

C Castro

Publications and source records attributed to C Castro.

At least 127 records · Page 7Linked to original sources
PubMed1981

Trypanosoma cruzi ribosomal RNA: internal break in the large-molecular-mass species and number of genes.

The large-molecular-mass ribosomal ribonucleic acid from Trypanosoma cruzi probably contains an internal break. The molecule can be obtained in its intact form or in its two fragments depending on the denaturing agents used for its purification and/or display. This break appears to be an in vivo late processing step rather than a random nucleolytic cleavage during in vitro manipulations. Calculations of mass, from gel electrophoretograms, for the large and small main ribosomal ribonucleic acid species and for the two chains derived from the large species gave values of 1.37, 0.84, 0.70 and 0.57 X 10(6) daltons, respectively. Sedimentation velocity measurements in sucrose gradients and in the analytical ultracentrifuge indicated sedimentation coefficients of 24 and 18 S for the large and small main species, respectively. Saturation hybridization curves showed that the nuclear genome, quantified by chemical analysis, contains about 114 ribosomal ribonucleic acid gene copies.

Animals↗
PubMed1981

[Early neonatal pneumococcal infections (author's transl)].

Five newborn infants with early pneumococcal infection are presented, two of them died. Until 1978 no cases of this infection were found in our Nursery. In the last three years pneumococcal septicemia has been responsible for nine percent of early neonatal infections. The clinical findings are identical to those seen in type-B beta hemolytic infections. The maternal genital tract colonization maight fetal colonization.

Apnea↗
PubMed1978

Jaccoud's arthropathy in patients with chronic rheumatic valvular heart disease.

In a prospective study over a period of 3 yr, involving all patients with rheumatic valvular heart disease seen at our hospital, we found the diagnostic signs of Jaccoud's arthropathy in 17 of 400 cases (4.2%). All 17 patients had a past history of acute arthritis involving the joints and showed deformities at the time of diagnosis. The valvular lesions were mitral and aortic in 11 cases, mitral in 5 cases and aortic in 1 case. The most frequent joint deformities were: ulnar deviation at the metacarpo-phalangeal joints (12 cases), lateral deviation at the metatarso-phalangeal joints (12 cases), and hammer toe deformity (6 cases). The deformities were reducible in all of them. None of the patients had pain or signs of acute inflammation and functional capacity was normal. Other causes of joint deformity were ruled out by means of radiographic and serologic studies. Jaccoud's arthropathy is not a rare entity and its recognition is important for a differential diagnosis with chronic arthritis of other etiologies, also associated with valvular heart lesions.

Adolescent↗
PubMed1976

The relationship between overdrive suppression and overdrive excitation in ventricular pacemakers in dogs.

We studied the excitatory and inhibitory effects of overdrive on idioventricular pacemakers in anesthetized dogs with recently induced complete atrioventricular block. The following results were obtained: (1) a slow driving rate may induce a temporary rhythm which may be reinstituted with additional stimuli; (2) the induced rhythm may appear as coupled extrasystoles which, on interruption of the drive, are found to be self-sustaining; (3) during continued slow driving, extrasystoles may appear and disappear in a cyclical manner; (4) a short period of fast driving may be followed by a fast new rhythm, the rate and duration of which are a function of the rate and duration of drive; (5) fast driving may induce a new rhythm at a rate below predrive control; (6) after a long period fast driving, only suppression follows; and (7) intermittent periods of fast driving lead to a summation of inhibition with each successive period. These results suggest the following conclusions: (1) under certain conditions, electrical driving instead of inducing suppression may induce a rhythm ("overdrive excitation") at a rate similar to, faster then, or slower ("inhibited excitation") than control; (2) the duration of diastole and the number of driven beats are major factors in the induction of new rhythms; and (3) overdrive excitation is counteracted by overdrive inhibition, with development of the former requiring fewer beats than the latter.

Animals↗
PubMedDate not supplied

Intramolecular glycosylation to form 4-methoxy-2,6-dioxopyrimidine nucleosides via O6,5'-cyclonucleosides.

Lewis-acid promoted intramolecular N1 glycosylation to form the novel O6,5'-cyclonucleoside 1a occurs in high yield from the corresponding acyclic thiophenyl-glycoside 12. The relative stability of the O6,5' tether compared with O2,5' and O2,3' tethers is reported. Cleavage of the anhydro bond was effected with aqueous base to yield the 4-methoxybarbituric acid nucleoside analogue 14.

Glycosylation↗
PubMedDate not supplied

Comparison of methods for the detection of treponema pallidum in lesions of early syphilis.

BACKGROUND: The clinical diagnosis of primary and secondary syphilis can be difficult because of the wide variability of lesions. The available laboratory tests (dark-field microscopy and direct fluorescent antibody) require specialized microscopes and skilled technicians, and serologic tests are insensitive in early infection. METHODS: Dark-field microscopy and monoclonal antibody staining were compared to a new solid-phase enzyme-linked immunosorbent assay (Visuwell test) for detection of T. pallidum in lesion exudate of 188 patients with genital lesions. RESULTS: Sixty-four patients (34%) had lesions of early syphilis diagnosed by either dark-field, monoclonal antibody staining, or both. The Visuwell test and dark-field examination were positive in 52 (81.3%) and 55 (85.9%) of the 64 patients, respectively, whereas the monoclonal antibody staining technique demonstrated the presence of T. pallidum in 59 (92.2%) of the 64 patients. The Visuwell test gave a negative result in 111 of 124 patients who had negative dark-field and direct fluorescent antibody test results (89.5% specificity). CONCLUSIONS: The Visuwell test is an alternative method for evaluating genital ulcers but is less sensitive and specific than existing tests.

Enzyme-Linked Immunosorbent Assay↗