Distribution of F-actin, alpha-actinin, tropomyosin, tubulin and organelles in Euglena gracilis by immunofluorescence microscopy

Euglena gracilis, a unicellular flagellated alga, can display numerous shape changes. These changes are most probably caused by a pellicle and an internal cytoskeleton. In this paper we studied the distribution of the cytoskeletal proteins actin, alpha-actinin, tropomyosin and tubulin in dark-adapted Euglena, using immunofluorescence microscopy. We found that F-actin, alpha-actinin, tropomyosin and tubulin have a distribution that is coincident in the plasma membrane and, in addition, alpha-actinin and tropomyosin are seen in small patches in the cytoplasm, and tubulin in the flagella. We have also studied the distribution of the endoplasmic reticulum, nucleus, and Golgi apparatus of these cells, using fluorescent probes. Both the endoplasmic reticulum and the Golgi apparatus have a meshwork pattern distributed throughout the cytoplasm, and the nucleus has a chromatin evenly distributed in the nucleoplasm.

Conventional radiation-biological dosimetry using frequencies of unstable chromosome aberrations

Frequency of chromosome aberrations detected by conventional cytogenetics is a very useful parameter in biological radiodosimetry. It can be used for estimating absorbed doses in individuals working with radioactive sources and individuals accidentally exposed to radiation. In the first case subjects wear physical dosimeters as a routine safety habit. Our laboratory at the Institute of Radioprotection and Dosimetry (IRD, Brazil) has been using conventional cytogenetic analysis to complement data obtained by physical dosimetry since 1983. Until now, we have investigated more than one hundred cases where individual physical dosimeters detected occupational exposure (above the safety limits allowed). In total, only 34% of these cases were confirmed by conventional cytogenetic dosimetry. We have also used conventional cytogenetic analysis following the radiation accident of Goiania (Brazil) in 1987. Peripheral lymphocytes from 129 exposed or potentially exposed individuals were analyzed for the frequencies of unstable chromosomal aberrations (dicentrics, centric rings and acentrics fragments) to estimate absorbed radiation doses. During the emergency period, doses were estimated to help immediate medical treatment using in vitro calibration curves produced before the accident. Later on, doses were assessed once more using new in vitro calibration curves. A drawback of this technique is that unstable aberrations are lost after exposure. To investigate the mean lifespan of lymphocytes containing dicentric and ring aberrations, we have followed 15 victims of the Goiania accident over all these years. Results suggest that the disappearance of unstable aberrations is dose-dependent. This could explain the variation in the results found among studies in this field.

Differences in the isodesmin pattern between the electric organs of Electrophorus electricus L

Desmin, the intermediate filament protein of muscle, is present in the electric organs of Electrophorus electricus L. as five isovariants, instead of the one to two isovariants found in muscle. We analyzed the isodesmin pattern in the three different electric organs using densitometry of Coomassie blue-stained bands in electrofocusing polyacrylamide gel electrophoresis. We were able to compare the relative amount of each of the five desmin isovariants in an isodesmin pattern characteristic of each electric organ. These patterns proved to be, in some cases, statistically different. Desmin in each electric organ could have slightly different functions in order to correlate with the organ-specific isovariant patterns.

Intermediate filament proteins in TPA-treated skeletal muscle cells in culture

The cocarcinogenic phorbol ester 13-tetradecanoyl-O-phorbol acetate selectively and reversibly inhibits the ongoing differentiation programme of chick muscle cells in culture. 13-tetradecanoyl-O-phorbol acetate promptly blocks spontaneous contractions in mature myotubes and induces them to retract, forming giant myosacs and concurrently stress fibre-like structures are assembled. Using indirect immunofluorescence to localise desmin, the muscle specific intermediate filament protein, it was shown that its distribution is longitudinally oriented in mature myotubes. In myosacs, desmin has a reticular pattern although not as linearly oriented as in control myotubes. Using gel electrophoresis of control and 13-tetradecanoyl-O-phorbol acetate treated cell extracts, three major protein bands were observed with molecular weight of 43, 50 and 55 kDa. They migrate as actin, desmin and vimentin, respectively. The 50 kDa and 55 kDa proteins were expressed more in 13-tetradecanoyl-O-phorbol acetate-treated cells. The 50 kDa band was confirmed as desmin by immunoblotting using anti-chicken desmin antibody. Two-dimensional gel electrophoresis analysis showed the appearance of more acidic isoforms of the 50 and 55 kDa proteins 13-tetradecanoyl-O- phorbol in acetate-treated cells. The 43 kDa protein was seen as three distinct isoforms in control cells and as only two isoforms in 13-tetradecanoyl-O-phorbol acetatetreated cells.

"Pararamose": an occupational arthritis caused by lepidoptera (Premolis semirufa). An epidemiological study

The frequency of "pararama" occupational accidents between 1988 and 1990 as well as some associated clinical manifestations are herein reported. Data were collected at an industrial rubber tree plantation, in the northern part of Brazil and compared with data similarly collected from 1971 to 1974 on the same plantation, before starting protective measures. "Pararama" is the popular name of the larval form of a native insect of the Amazonian region, Premolis semirufa. During the study period, the annual average number of latex extractors was 337 and 60 accidents caused by "pararama" were registered. The annual average number of accidents per worker from 1971 to 1974 was 0.117 and in the period of this study, 0.063 (p = 0.061). Nineteen injured subjects were clinically evaluated and 13 of them were symptomatic. There was a statistically significant association between multiple accidents and the presence of symptoms (p = 0.001). "Pararamose", an occupational arthropathy, which may evolve with functional impairment of the affected joint, can be prevented with the latex extractors education and the institution of prophylactic measures, such as the use of gloves, boots and protective glasses.

[The profile of nursing teachers in undergraduate courses in greater São Paulo]

This paper searches to identify some aspects of the profile of the undergraduate nursing faculty members and to detect the differences and similarities among the group of teachers of public and private schools. A sample of 120 faculty members of five schools was studied in August of 1990 using a questionnaire. The data was analysed according to the following categories: demographic data, social economical status, university stand, professional development and perspectives. The results showed that there are more similarities than differences within this faculty members, once they belong to the an homogeneous social, economical and cultural class with a few exceptions.

MyoD converts primary dermal fibroblasts, chondroblasts, smooth muscle, and retinal pigmented epithelial cells into striated mononucleated myoblasts and multinucleated myotubes

Shortly after their birth, postmitotic mononucleated myoblasts in myotomes, limb buds, and conventional muscle cultures elongate and assemble a cohort of myofibrillar proteins into definitively striated myofibrils. MyoD induces a number of immortalized and/or transformed nonmuscle cells to express desmin and several myofibrillar proteins and to fuse into myosacs. We now report that MyoD converts normal dermal fibroblasts, chondroblasts, gizzard smooth muscle, and pigmented retinal epithelial cells into elongated postmitotic mononucleated striated myoblasts. The sarcomeric localization of antibodies to desmin, alpha-actinin, titin, troponin-I, alpha-actin, myosin heavy chain, and myomesin in these converted myoblasts are indistinguishable from in vivo and in vitro normal myoblasts. Converted myoblasts fuse into typical anisodiametric multinucleated myotubes that often contract spontaneously. Conversion and subsequent expression of the skeletal myogenic program are autonomous events, occurring in four nonmuscle microenvironments consisting of different combinations of foreign extracellular matrix molecules. Early events associated with conversion by MyoD involve (i) withdrawal from the cell cycle, (ii) down-regulation of the subverted cell's ongoing differentiation program, and (iii) initiation of desmin synthesis in presumptive myoblasts and dramatic redistribution of microtubules and desmin intermediate filaments in postmitotic myoblasts.

Cancer incidence rates among Japanese immigrants in the city of São Paulo, Brazil, 1969-78

Cancer incidence rates among first-generation Japanese immigrants in the city of São Paulo, Brazil, were estimated from the data of the São Paulo Cancer Registry during the years 1969 to 1978. From all registered cases, 2,179 cancer cases of Japan-born residents (1,288 males, 891 females) were selected and age-specific and summary age-adjusted incidence rates (AAIR) were calculated for the selected sites of cancer. The AAIR for all sites except non-melanoma skin cancer was 195.2 per 100,000 population (95 percent confidence interval: 176.4-214.1) in males and 147.3 (134.6-160.0) in females. Stomach cancer had the highest incidence rate of all cancers in both sexes (males, 69.3; females, 32.0). This was followed by cancer of the lung (22.5), esophagus (10.2), colon (8.3), and prostate (7.1) in males; and by breast (24.0), cervix (18.0), colon (8.4), and lung (7.2) in females. When these rates were compared with those among Japanese in Japan, cancer of the stomach and rectum revealed significantly lower rates, while non-melanoma skin cancer, and prostate and breast cancer showed higher rates. No significant increase of colorectal cancer was recognized among Japanese immigrants in São Paulo, contrary to the remarkably high rates of colorectal cancer being observed among Japanese immigrants in the US.

Complete denture retention. Part II: Wettability studies on various acrylic resin denture base materials

The objective of this study was to characterize in vitro selected acrylic resin denture base materials by water-contact angle measurements. The sessile drop method and the underwater-bubble method were used. The results obtained from these measurements are discussed in terms of contact angle and polymer-water work of adhesion hysteresis. On polished heat-polymerized samples this hysteresis results from the reorientation of superficial polymer chains. The combined effect of increased sample roughness and of the entrapment of water droplets in the pores of material gives rise to the highest contact-angle hysteresis observed on sand-abraded samples. On the basis of physical analysis of the mechanism involved in complete denture retention, developed in Part I of this work, it is believed that the sand-abraded material is the most convenient for the retention of the complete denture.

Desmin heterogeneity in the main electric organ of Electrophorus electricus

Desmin, the muscle-specific intermediate filament protein was purified from the main electric organ of Electrophorus electricus. It is shown that pure desmin can be separated into 5 isoforms presenting different isoelectric points. These isoforms have similar molecular weight, react with an antibody directed against desmin and generate identical peptides after digestion with protease V8 from Staphylococcus aureus.

Loss of extrachromosomal resistances in Staphylococcus aureus by treatment with guanidine hydrochloride

The addition of subinhibitory concentrations (optimal 1.8 mg ml-1) of guanidine hydrochloride to broth cultures of three strains of Staphylococcus aureus was followed by loss of penicillin and cadmium resistance. The proportion of sensitive variants, although variable, was higher than in untreated cultures. The 'penicillinase plasmid' was absent from two cultures sensitive to penicillin and cadmium. The genes for penicillinase production in one culture (13136) were apparently carried by a plasmid of 105 x 10(6) daltons.