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Biomedical subjects

G Lobo

Publications and source records attributed to G Lobo.

At least 19 recordsLinked to original sources
PubMed2002

Contribution of calcium and other dietary components to global variations in bone mineral density in young adults.

A research project on comparative international studies of osteoporosis using isotope techniques was organized by the International Atomic Energy Agency (IAEA) with the participation of 12 countries (Brazil, Canada, Chile, China, Croatia, Hungary, Philippines, Russia, Singapore, South Africa, Turkey, and the United Kingdom). Participating centers in 11 countries (all but the UK) made measurements and collected data on men and women aged 15 to 49 years. In addition to studies of bone mineral density (BMD) at the femoral neck and lumbar spine using DEXA, anthropometric, lifestyle, and nutritional data were also collected. The results of the nutritional studies are reviewed in this paper. Overall, about 8% of the observed variability in spine BMD could be attributed to nutritional factors in men and women; in men, no such relationship could be determined. No single nutritional component (not even calcium) stood out as being of particular importance across all participating centers.

Absorptiometry, Photon↗
PubMed2001

Synthesis of quinolinyl chalcones and evaluation of their antimalarial activity.

Quinolinyl chalcones were synthesized and evaluated for their inhibition of the Plasmodium falciparum cystein protease falcipain and their activity against cultured P. falciparum parasites. They were also tested for in vivo efficacy in a rodent P. berghei model. Their activity against falcipain and as antimalarials was moderate, but antimalarial activity was probably not due to the inhibition of falcipain and may follow a different mechanism. 1-(2,4-Dichlorophenyl)-3-[3-(2-chloro-6,7-dimethoxiquinolinyl)]-2-propen-1-one 3j was the most promising compound among those here reported (IC50 19.0 microM).

Animals↗
PubMed2001

In vitro antifungal evaluation and structure-activity relationships of a new series of chalcone derivatives and synthetic analogues, with inhibitory properties against polymers of the fungal cell wall.

Here we report the synthesis, in vitro antifungal evaluation and SAR study of 41 chalcones and analogues. In addition, all active structures were tested for their capacity of inhibiting Saccharomyces cerevisiae beta(1,3)-glucan synthase and chitin synthase, enzymes that catalyze the synthesis of the major polymers of the fungal cell wall.

Antifungal Agents↗
PubMed2000

Does perchlorate in drinking water affect thyroid function in newborns or school-age children?

Perchlorate is known to suppress thyroid function by inhibiting uptake of iodide by the human thyroid at doses of 200 mg/day or greater. A study was conducted to investigate the potential effects of perchlorate in drinking water on thyroid function in newborns and school-age children. A total of 162 school-age children and 9784 newborns were studied in three proximate cities in northern Chile that have different concentrations of perchlorate in drinking water: Taltal (100 to 120 micrograms/L), Chañaral (5 to 7 micrograms/L), and Antofagasta (non-detectable: < 4 micrograms/L). Among schoolchildren, no difference was found in thyroid-stimulating hormone levels or goiter prevalence among lifelong residents of Taltal or Chañaral compared with those of Antofagasta, after adjusting for age, sex, and urinary iodine. No presumptive cases of congenital hypothyroidism were detected in Taltal or Chañaral; seven cases were detected in Antofagasta. Neonatal thyroid-stimulating hormone levels were significantly lower in Taltal compared with Antofagasta; this is opposite to the known pharmacological effect of perchlorate, and the magnitude of difference did not seem to be clinically significant. These findings do not support the hypothesis that perchlorate in drinking water at concentrations as high as 100 to 120 micrograms/L suppresses thyroid function in newborns or school-age children.

Age Distribution↗
PubMed2000

[Salivary gland scintigraphy en Sjogren syndrome and its relation with the result of lip biopsy. Comparative study with a control population].

BACKGROUND: Salivary gland scintigraphy allows a non invasive, morphological and functional assessment of parotid and submaxillary salivary glands. AIM: To describe the main features of salivary gland scintigraphy in patients with Sjögren syndrome, rheumatic fibromyalgia and normal controls and compare the results with lip biopsy. PATIENTS AND METHODS: Sixty one normal controls, 66 patients with Sjögren syndrome and 18 patients with rheumatic fibromyalgia were studied. For the diagnosis of Sjögren syndrome and fibromyalgia rheumatica, the Modified European and American College of Rheumatology criteria were used, respectively. Lip biopsies were obtained in 52 patients with Sjögren syndrome. Scintigraphy was done with a gamma camera and computer after the administration of 99mTc-pertechnetate, obtaining images during 30 min and creating time/activity curves. Scintigraphy was classified as normal, with mild or severe alterations. RESULTS: Scintigraphy was normal in 74% of control subjects and in 26%, it had mild alterations. In 72% of patients with rheumatic fibromyalgia, scintigraphy was normal whereas in 28%, it had mild alterations. In 27% of patients with Sjögren syndrome, scintigraphy was normal, in 27% it had mild alterations and in 46%, severe alterations. There was a positive and significant correlation between pathological alterations of salivary glands and scintigraphic alterations (r = 0.642, p < 0.001). CONCLUSIONS: Severe scintigraphic alterations of salivary glands strongly support the diagnosis of Sjögren syndrome. Mild alterations are non specific and a normal scintigraphy does not exclude the diagnosis.

Adolescent↗
PubMed1999

[Bone scintigraphy in prostatic cancer. Correlation with clinical and laboratory features and with survival].

BACKGROUND: The yield of bone scintigraphy is specially good in some types of neoplasia such as mammary and prostate carcinoma, whose metastases cause a marked osteoblastic reaction in bone. AIM: To assess the usefulness of bone scintigraphy in patients with prostate carcinoma. PATIENTS AND METHODS: A retrospective analysis of bone scintigrams performed to 79 patients with prostate carcinoma aged 56 to 83 years old, describing their relationship with prostate specific antigen and bone pain. The predictive value of bone scan, prostate specific antigen and clinical variables was analyzed using Kaplan Meier survival tables. RESULTS: Scintigraphy disclosed bone metastases in 22 patients (28%). The most frequently involved zones were pelvis (86%), rib cage (67%) and spine (57%). The association with pain was low specially for limbs, rib cage and skull. The better efficacy of prostate specific antigen for the prediction of bone metastases was obtained with a cutoff value of 50 ng/ml (sensitivity 72%, specificity 86%). With a cutoff value of 10 ng/ml, the negative predictive value was 100%. The only significant predictor of a lower patient survival was the presence of bone metastases on bone scintigraphy. CONCLUSIONS: In this series of patients, bone scintigraphy was an excellent diagnostic tool for bone metastases and had a survival prognostic value.

Aged↗
PubMed1997

Synthesis and antimalarial effects of phenothiazine inhibitors of a Plasmodium falciparum cysteine protease.

Acridinediones have previously been shown to have potent antimalarial activity. A series of sulfur isosteres of acridinediones have been synthesized and evaluated for their inhibition of the Plasmodium falciparum cysteine protease falcipain and for their antimalarial activity. A number of these phenothiazines inhibited falcipain and demonstrated activity against cultured P. falciparum parasites at low micromolar concentrations. We propose that the compounds exerted their antimalarial effects by two mechanisms, one of which involves the inhibition of falcipain and a consequent block in parasite degradation of hemoglobin. These compounds and related phenothiazines are worthy of further study as potential antimalarial agents.

Animals↗
PubMed1996

Effects of freezing and canning of papaya slices on their carotenoid composition.

An HPLC study of the carotenoid composition of fresh, frozen and canned papaya fruit slices was done. There were no qualitative differences between the carotenoid patterns of fresh and frozen papaya fruit slices (cultivar Sunrise). The major carotenoids found in papaya extracts were lycopene and carotenol fatty acid esters of beta-cryptoxanthin and beta-cryptoxanthin-5, 6-epoxide. Other xanthophylls detected were beta-cryptoxanthin, trans-zeaxanthin and cryptoflavin. It was possible to determine the quantitative losses of carotenoids in papaya slices as a result of the freezing process and frozen storage, since samples of these fruits were available before processing. The pigment pattern of the canned product showed lycopene as being a major pigment. Thermal treatment induced the degradation of carotenol fatty acid esters of xanthophylls. The freezing and canning processing of papaya slices led to significant decreases in the total carotenoids quantified by HPLC, with frozen female slices and canned samples showing lower amounts of pigments. Hunter colour values of frozen slices were similar to those of fresh papaya fruit slices.

Carotenoids↗
PubMed1996

Synthesis of pyridopyrimidone derivatives and their activity against P. falciparum in vitro.

Pyridopyrimidone derivatives 4a-d and 5a- were synthesized as potential antimalarial agents on the basis of the pharmacological properties of existing quinolone analogues such as ciprofloxacine IC50 39.8 microM. Meanwhile among these new compounds, only the 3-amino-7-methyl-1(H)pyrazolo[3,4-b]-pyrido [1,2: 1'2']pyrimido-4-ona 4b, produces significant antimalarial activity IC50 0.42 microM against P. falciparum in vitro. The remaining compounds were effective as antimalarial agents leading from IC50 1.0 microM to IC50 4.47 microM.

Animals↗
PubMed1993

[Rheumatoid arthritis. Therapeutic efficacy of methotrexate and its hepatotoxic effects].

The efficacy and toxicity (specially hepatic) of methotrexate in low doses (7.5 mg/week) was prospectively assessed in 21 patients with rheumatoid arthritis refractory to treatment with gold or penicillamine, during two years. Three patients were prematurely withdrawn from the protocol. A fast and significant improvement of RA was observed during the first six months, which tapered thereafter. Erythrocyte sedimentation rate decreased from 51.5 +/- 20.1 to 27.7 +/- 11.5 mm/h (p < 0.05). A rise in serum transaminases, always raising to less than twice the normal value, was observed in 75% of patients in some moment of the follow up. Hepatic scintigraphy did not show significant changes. Hepatic histological alterations were mild and no changes were observed after two years of treatment. The main secondary effects were moderate and transitory gastrointestinal and hematological disturbances. The prednisone dose was decreased from 6.8 +/- 2.6 to 4.8 +/- 1.9 mg/day at twelve months. There were no withdrawals due to drug toxicity. It is concluded that methotrexate proved to be efficacious in the treatment of rheumatoid arthritis refractory to conventional treatments. Its secondary effects, although frequent, were discrete and transitory and there were no changes in liver histology.

Adult↗
PubMed1993

[Yield of myocardial perfusion study with Thallium 201 in coronary artery disease: planar analysis].

The yield of exercise thallium-201 scintigram was studied in a group of 101 patients with suspected coronary artery disease or with a history of an old acute myocardial infarction. The thallium perfusion imaging was performed with planar technology and was interpreted visually. Its results were compared with conventional exercise testing and the results of a coronary arteriography performed within 30 days. Global sensitivity for conventional exercise testing was 60.4%, which increased to 78.2% with the thallium study. Specificity was raised from 47.2 to 84.8%. In patients with one, two or three vessel disease, thallium scintigram was abnormal in 95.1%, 96.6% and 100% respectively (NS).

Adult↗
PubMed1991

[Detection of viable myocardium by means of stress test with thallium 201: usefulness of delayed imaging].

Delayed imaging may help detect viable myocardium after stress Thallium scintigraphy. In 22 patients who had sustained myocardial infarction we performed a stress Thallium test followed by imaging after 24 hr. Delayed reperfusion was observed in 57% of segments showing no reperfusion at 4 hr, which is similar to findings reported in the literature. We proposed that delayed imaging should be performed in all patients showing perfusion defects at 4 hr. Even though a better image may be obtained using reinjection of Thallium, delayed imaging may be the technique of choice to reduce the cost of the test.

Aged↗
PubMed1991

[Diastolic dysfunction in hypertrophic myocardiopathy: evaluation with radioisotopic ventriculography].

Diastolic function was evaluated in 13 patients with hypertrophic cardiomyopathy and 10 normal subjects of comparable age. Time-activity curves were used to derive peak filling rate, time to peak filling rate and average filling velocity during the first third of diastole. Left ventricular ejection fraction was significantly higher in patients with hypertrophic cardiomyopathy. Time to peak filling rate and filling velocity during the first third of diastole were significantly lower in patients compared to controls. Thus, radionuclide techniques can be used to evaluate diastolic filling in clinical practice.

Adolescent↗
PubMed1990

[The assessment of myocardial perfusion with thallium-201 in patients with a complete left His bundle-branch block].

Thallium-201 myocardial scintigraphy was used to evaluate coronary perfusion in 20 patients with left bundle branch block suspected of having coronary artery disease. Contemporary coronary arteriography was performed in 9 of these patients. Sensitivity and specificity of the method was similar to that obtained in patients without LBBB. A false positive results indicated ischemia of the interventricular septal region in a patient with normal coronary arteries, a known limitation of the method.

Aged↗
PubMed1989

[Myocardial perfusion during exercise and rest in coronary patients. Evaluation with a thallium 201 analog (isonitrile-technetium 99 m)].

Isonitrile-technetium, a Thallium 201 analog, was used for myocardial perfusion imaging in 12 patients with known coronary heart disease. 10-40 mCu of the isotope were injected at maximal effort during a Bruce stress test. Imaging was performed using 3 projections immediately after exercise and 24 hr later, using a gamma camera attached to a computer. Myocardial necrosis was detected with a sensitivity of 89% and specificity of 63%. Corresponding figures for stress induced ischemia were 89% and 100%. Accurate localization of ischemia or necrosis was obtained in 70% of all cases, improving to 100% in cases of total artery occlusion. These results, similar to those reported in the literature, encourage the use of Tc labeled isonitrile for myocardial perfusion imaging whenever Thallium 201 is difficult to obtain.

Adult↗