Biomedical subjects

R M Moraes

Publications and source records attributed to R M Moraes.

8 recordsLinked to original sources

PubMed2003

Gas exchange, growth, and chemical parameters in a native Atlantic forest tree species in polluted areas of Cubatão, Brazil.

The Atlantic forest species near the industrial complex of Cubatão, Brazil have been subjected to heavy air pollution for decades. In this study, we used some physiological parameters (gas exchange, growth and chemical contents) to biomonitor the effects of air pollution on Tibouchina pulchra, one of the most common tree species in this forest. Under standardized conditions, saplings were exposed to the environment from April to July and from July to September of 1998, at three different sites in the vicinity of the industrial complex: the Valley of Pilões River (VP), the control area; the Valley of Mogi River (VM), near fertilizer, metallurgical, and cement industries sustaining high concentrations of fluorides, N and S oxides, and particulate materials; and Caminho do Mar (CM), near petrochemical industries under N and S oxides, photooxidants, and organic compounds. Plants exposed to CM and VM conditions presented visible injuries, reductions in net photosynthesis, growth parameters, and ascorbate concentrations, and increased F, N, and S foliar concentrations. These results indicate that the environmental conditions around these industries are still harmful to plants.

Air Pollutants↗

PubMed2002

Tropical fruit trees as bioindicators of industrial air pollution in southeast Brazil.

Psidium guajava L., Psidium cattleyanum Sabine and Mangifera indica L. were tested under field conditions as possible tropical bioindicators of industrial air pollution. The study was performed around the industrial complex of Cubatão, SE Brazil, which comprises 23 industries, including fertilizer, cement, chemical, petrochemical, and steel plants, with 110 production units and 260 emission sources of pollutants. Saplings were exposed to environmental conditions during four periods of 16 weeks each (September 1994-September 1995), at four different sites in the coastal mountains near the industrial complex: the Valley of Pilões River (VP), the reference area; the Valley of Mogi River (VM), with high contamination of particulate matter, fluorides (F), sulfur (S) and nitrogen (N) compounds; Caminho do Mar (CM1, CM2), mainly affected by organic pollutants, S and N compounds, and secondary pollutants; and Paranapiacaba (PP), affected by secondary pollutants, such as ozone. M. indica did not adapt to the climatic conditions at the exposure sites. In the two Psidium species, the presence of visible symptoms, root/shoot ratio, foliar contents of F, S and N, amounts of ascorbate (AA) and water-soluble thiols (-SH), as well as peroxidase activity (POD) were determined. P. guajava showed higher foliar accumulation of F, S and N, more pronounced alterations of biochemical indicators, and less visible leaf injury than P. cattleyanum. P. guajava may be used as an accumulative indicator in tropical climates, while further studies will be needed before P. cattleyanum might be applied as a sensitive species in biomonitoring programs.

Air Pollutants↗

PubMed2001

High yield of podophyllotoxin from leaves of Podophyllum peltatum by in situ conversion of podophyllotoxin 4- O-beta-D-glucopyranoside.

Rehydration of powdered tissues of Podophyllum peltatum L. prior to extraction with an organic solvent allows endogenous beta-glucosidases to hydrolyze lignan 4-O-beta-D-glucosides in situ and increase the yield of podophyllotoxin. Aqueous extraction of rhizomes and leaves of P. peltatum yielded 4- to 10-fold greater quantities of podophyllotoxin than the traditional ethanolic extraction. Most significantly, leaves were shown to contain over 52 mg of podophyllotoxin per g of dry weight (5.2%), exceeding levels previously reported from any source. These results point to the use of leaves harvested from cultivated P. peltatum as an attractive alternative to the destructive collection of natural populations.

Glucosides↗

PubMed2001

Podophyllotoxin lignans enhance IL-1beta but suppress TNF-alpha mRNA expression in LPS-treated monocytes.

There exists a growing body of research which indicates that antimitotics such as taxol and colchicine influence cytokine gene expression. In the present study we examined the effect of podophyllotoxin and six analogs on nuclear factor kappa B (NF-kappa B) activation, and on interleukin-1 beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha) mRNA expression in human THP-1 monocytes. All compounds were inactive between 0.001microM and 10microM when tested alone. However, podophyllotoxin (0.1 microM) enhanced LPS-induced NF-kappa B activation and IL-1beta mRNA expression between 2 and 3-fold. In contrast, LPS-induced TNF-alpha mRNA expression was decreased between 3 and 6-fold. Comparable results were also observed with the three analogs acetylpodophyllotoxin, 4'-demethylpodophyllotoxin and alpha-peltatin. The remaining three analogs (podophyllotoxin-4-O-glucoside, beta-peltatin-beta-D-glucopyransoide and 1,2,3,4-dehydrodesoxypodophyllotoxin) were inactive. Clearly certain structural features such as the presence of a glycosidic group or ring aromatization results in loss of biological activity. Interestingly, the analogs that were inactive in our assays have also been previously shown to lack affinity for tubulin binding. These results suggest that during the initial hours of exposure to podophyllotoxin or specific analogs these compounds do not act as independent stimulants of human monocyte activation, but can selectively enhance or suppress LPS-induced cytokine gene expression.

Cells, Cultured↗

PubMed2000

Podophyllotoxin.

Podophyllin, an ethanolic extract of Podophyllum peltatum L. or P. emodi Wall (syn. P. hexandnum Royle), is a good source of the aryltetralin-type lignan, podophyllotoxin. The latter compound, as well as its congeners and derivatives exhibit pronounced biological activity mainly as strong antiviral agents and as antineoplastic drugs. The podophyllotoxin derivatives etoposide, etopophos (etoposide phosphate), and teniposide are thus successfully utilized in the treatment of a variety of malignant conditions. Continued research on the Podophyllum lignans is currently focused on structure optimization to generate derivatives with superior pharmacological profiles and broader therapeutic scope, and the development of alternative and renewable sources of podophyllotoxin.

Podophyllotoxin↗

PubMed1999

Phytotoxic lignans of Leucophyllum frutescens.

Bioassay-guided fractionation of the hexane:ethyl acetate (1:1) extract of the leaves of Leucophyllum frutescens (Berl.) I.M.Johnst (Scrophulariaceae) led to the isolation of its phytotoxic constituents diayangambin (1), epiyangambin (2), diasesartemin (3) and epiashantin (4). Phytotoxicity was demonstrated as inhibition of seed germination of Agrostis stolonifera cv. penncross (Poaceae) and inhibition of development of Lactuca sativa L. (Asteraceae) seedlings in a microassay using 24-well plates. Compound 1 was the most phytotoxic to L. sativa, showing strong inhibitory activity at 110 microM. Compound 1 was more active than 2 and 3 in inhibiting the growth of A. stolonifera with I(50) values of 160, 670 and 930 microM, respectively. At a concentration of 500 microM, these compounds inhibited all phases of onion root cell division. This is the first demonstration of antimitotic activity of these furofuran lignans, and the first report of their isolation from this species.

Germination↗

PubMed1993

Viral, bacterial and parasitic pathogens associated with severe diarrhoea in the city of São Paulo, Brazil.

Viral, bacterial and parasitic pathogens associated with diarrhoea were studied in infants and young children admitted to the paediatric clinic of the University Hospital of São Paulo during the period of 13 months. A recognised pathogenic organism was detected in 78% of the diarrhoeic patients, 6% of whom had a mixed infection with two agents. Enteropathogenic E. coli (EPEC) was the most common enteropathogen detected (22%), followed by rotavirus (19%) and adenovirus (10%). Altogether 6% had diarrhoea associated with Salmonella or Shigella and 3% showed diarrhoeal illness associated with astrovirus. Infants less than 6 months of age were most commonly infected with enterobacteria (35%), mainly enteropathogenic E. coli (30%), whereas children 6 months to 2 years presented more often with viruses (38%), mainly rotaviruses (25%). Enteropathogens were found during all seasons of the year and rotaviruses showed a seasonal variation.

Acute Disease↗

PubMedDate not supplied

Development of trypanosomatids in the phytophagous insect Dysdercus peruvianus (Hemiptera: Pyrrochoridae). A light and eletron microscopic study.

Experimental infections of the phytophagous Hemiptera Dysdercus peruvianus with different trypanosomatids were studied for up to 55 days by light microscopy while the course of infection with Leptomonas seymouri and the Leptomonas isolate 49/553G.O. was analyzed by electron microscopy. Rates of infection of D. peruvianus varied according to the infecting flagellate. The lower part of the midgut was found to be the preferential site of colonization where most flagellates were found isolated or arranged in clumps or rosettes. Specialized junctional structures with host cells were never observed. Flagellates could also be seen inside midgut cells within a parasitophorous vacuole. Infection of haemocoele and salivary glands was also observed.

Animals↗