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Biomedical subjects

N Bromberg

Publications and source records attributed to N Bromberg.

14 recordsLinked to original sources
PubMed2005

Violacein cytotoxicity on human blood lymphocytes and effect on phosphatases.

Given the importance of protein phosphorylation in the context of cellular functions, abnormal protein phosphatase activity has been implicated in several diseases, including cancer. These critical roles of protein phosphatases qualify them as potential targets for the development of medicinal compounds that possess distinct modes of action such as violacein. In this work, studies with this natural indolic pigment at a concentration of 10.0 micromol L(-1) demonstrated a 20% activation of total protein phosphatase extracted from human lymphocytes. Although no alteration was observed on protein tyrosine phosphatase (CD45), 30% of inhibition was achieved in cytoplasmatic protein phosphatase activity after incubation with 10.0 micromol L(-1) violacein. Additionally, 5.0 micromol L(-1) of violacein inhibited by 50% the serum tartrate-resistant acid phosphatase activity. Violacein presented toxic effect on lymphocytes with IC50 values of 3 and 10 micromol L(-1) for protein content and protein phosphatase activity, respectively. These findings suggest an important role for protein phosphatases in the mechanisms controlling proliferation and cell death.

Cells, Cultured↗
PubMed2001

Kinetic studies on veratryl alcohol transformation by horseradish peroxidase.

A number of peroxidases, such as lignin peroxidase and manganese peroxidase have proved to be useful for industrial applications. Some studies on the effects of temperature and pH stability have been carried out. It is known that veratryl alcohol increases their stability in the range 28-50 degrees C and is oxidized, leading to veratryl aldehyde formation. Similar results with horseradish peroxidase (HRP) in the presence of cofactors were found, but the oxidation of veratryl alcohol in the absence of cofactors was extremely labile at acid pH and inactivated in a few minutes. Considering the growing industrial application of HRP, knowledge of its stability and denaturation kinetics is required. In this study, horseradish peroxidase pool (HRP-VI) and its isoenzymes HRP-VIII (acid) and HRP-IX (basic) have been shown to catalyze the oxidation of veratryl alcohol to veratryl aldehyde in the presence of hydrogen peroxide at pH 5.8 in the 35-45 degrees C range and in the absence of any cofactors. Heat and pH denaturation experiments in the presence and absence of veratryl alcohol incubation were conducted with HRP-VI and HRP-IX isoenzymes. HRP-IX was the most active isoenzyme acting on veratryl alcohol but HRP-VI was the most stable for the temperature range tested. At 35 degrees C the HRP pool presented decay constant (Kd) values of 5.5 x 10(-2) h(-1) and 1.4 10(-2) h(-1) in the absence and presence of veratryl alcohol, respectively, with an effective ratio of 3.9. These results present a new feature of peroxidases that opens one more interesting application of HRP to industrial processes.

Benzyl Alcohols↗
PubMed2001

Violacein biotransformation by basidiomycetes and bacteria.

AIMS: The biotransformation study of the pigment (violacein) produced by Chromobacterium violaceum, was verified by its decolorization utilizing six different organisms in liquid and solid media. METHODS AND RESULTS: Lentinus edodes showed the fastest violacein decolorization (8th d) in solid medium whereas in a liquid medium, violacein was rapidly decolorized in 2 h by Azotobacter vinelandii. Adsorption experiments indicated no significant contribution for the decolorization process for all organisms in both media. CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY: The results showed poor lignin peroxidase activity in both media but manganese peroxidase and laccase activity varied according to the organism used. Siderophores presence was also detected in all organisms mainly in the liquid medium experiment.

Adsorption↗
PubMed2000

A z gain nonuniformity correction for multislice volumetric CT scanners.

This paper presents a calibration and correction method for detector cell gain variations. A key functionality of current CT scanners is to offer variable slice thickness to the user. To provide this capability in multislice volumetric scanners, while minimizing costs, it is necessary to combine the signals of several detector cells in z, when the desired slice thickness is larger than the minimum provided by a single cell. These combined signals are then pre-amplified, digitized, and transmitted to the system for further processing. The process of combining the output of several detector cells with nonuniform gains can introduce numerical errors when the impinging x-ray signal presents a variation along z over the range of combined cells. These numerical errors, which by nature are scan dependent, can lead to artifacts in the reconstructed images, particularly when the numerical errors vary from channel-to-channel (as the filtered-backprojection filter includes a high-pass filtering along the channel direction, within a given slice). A projection data correction algorithm has been developed to subtract the associated numerical errors. It relies on the ability of calibrating the individual cell gains. For effectiveness and data flow reasons, the algorithm works on a single slice basis, without slice-to-slice exchange of information. An initial error vector is calculated by applying a high-pass filter to the projection data. The essence of the algorithm is to correlate that initial error vector, with a calibration vector obtained by applying the same high-pass filter to various z combinations of the cell gains (each combination representing a basis function for a z expansion). The solution of the least-square problem, obtained via singular value decomposition, gives the coefficients of a polynomial expansion of the signal z slope and curvature. From this information, and given the cell gains, the final error vector is calculated and subtracted from the projection data.

Algorithms↗
PubMed1992

The evolution of Graves' ophthalmopathy during treatment with antithyroid drug alone and combined with triiodothyronine.

We analyzed the evolution of the ophthalmopathy associated with Graves' hyperthyroidism in 45 patients treated with two different antithyroid drug regimens. Group A patients (n = 31) received either methimazole (40-100 mg daily) or propylthiouracil (400-900 mg daily) combined with T3 daily throughout treatment. Group B patients (n = 14) were treated with conventional regimen with lower doses of either methimazole (5-25 mg daily) or propylthiouracil (50-300 mg daily) and no T3 addition. Eye signs and proptosis measurement were evaluated just before the beginning of the treatment and compared with the results after antithyroid drug withdrawal. Improvement of the eye signs considered on grounds of the NOSPECS classification was greater in group A than group B (p less than 0.01). Also, the decrease in proptosis measurement was greater (p less than 0.01) in patients treated with combined regimen (21.5 +/- 2.4 mm to 20.4 +/- 2.3 mm) than in patients receiving conventional therapy (20.4 +/- 1.6 mm to 20.0 +/- 1.7 mm). Serum thyroglobulin concentrations did not correlate with either the severity or the evolution of the ophthalmopathy. Negative serum antithyroglobulin antibody (TgAb) was associated with the improvement of the ophthalmopathy that was noted in 24 out of 27 patients (Chi-Square = 5.84; p less than 0.001). Thus, serum TgAb levels might have some connection with progression of eye signs but serum Tg concentration does not. Our study suggests that in most patients the transition from hyperthyroidism to euthyroidism induced by antithyroid drug therapy is associated with the improvement of the Graves' ophthalmopathy. However, no marked difference can be drawn between the two treatment regimens.

Adolescent↗
PubMed1991

Serum thyroid-stimulating antibody, thyroglobulin levels, and thyroid suppressibility measurement as predictors of the outcome of combined methimazole and triiodothyronine therapy in Graves' disease.

The value of the criteria used to anticipate the outcome of treatment of Graves' hyperthyroid patients with methimazole (MMI) remains controversial. We have reported that high MMI doses combined with T3 administration was correlated with higher remission rates. In this study, we used the lowest MMI dose able to control the hyperthyroidism, keeping the free T4 index (FT4I) values below the normal range throughout treatment, and compared the results with patients treated with a high MMI regimen. Both groups received T3. We also evaluated the usefulness of goiter size, serum thyroid-stimulating antibody (TSAb: adenylate cyclase stimulation in human thyroid membrane), thyroglobulin (Tg) levels, and the T3 suppressibility of 24 h RAIU as prognostic markers for the outcome of Graves' disease therapy. Twenty-four Graves' hyperthyroid patients were treated with high MMI dose (mean +/- SD 60 +/- 19, range 40-120 mg daily), and 25 patients received low MMI dose (17 +/- 4.3, 5-20 mg daily). T3, 75 micrograms daily, was given to both groups of patients for 15 +/- 4 (13-22) months of treatment. After cessation of drug therapy, 31 patients (63%) remained euthyroid for 18 +/- 3 (13-49) months of follow-up, 15 (62.5%) and 16 (64%) patients in the high and low dose groups, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Adverse effects related to thionamide drugs and their dose regimen.

The authors studied 389 Graves' hyperthyroid patients receiving either high propylthiouracil (PTU) or methimazole (MMI) daily doses or low doses to evaluate whether adverse effects were related to the thionamide drugs or its daily dose regimen. Group 1 patients (n = 286) received high PTU (728 +/- 216 mg/day, n = 92) or MMI (60 +/- 19 mg/day, n = 94) doses, and group 2 patients (n = 103) were treated with low PTU (255 +/- 85 mg/day, n = 39) or MMI (23 +/- 10 mg/day, n = 64) doses. Major adverse effects were observed in 11 (2.8%) patients. Of these, four (1.0%) had agranulocytosis, two (0.5%) were granulocytopenic and five (1.3%) had hepatotoxicity. Agranulocytosis occurred in two patients from each group, 0.7% and 1.9%, respectively from group 1 and group 2. There was no significant difference between the groups or the types of thionamide. There also was no correlation with the patients' age. All of the patients were hyperthyroid, and its onset occurred in the first to third month of treatment. Full recovery was achieved in all cases after drug withdrawal. Four of 5 patients with hepatotoxicity were treated with high PTU doses, and one patient received low MMI doses (p less than .05). All patients were euthyroid. Arthralgias, skin rash and gastric intolerance, the minor adverse effects of thionamides studied, were observed in 52 (13.4%) of the patients. Although no significant differences were found, most of the patients experiencing side effects were from group 1 an received MMI therapy. These adverse effects did not demand drug withdrawal.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Graves' disease and Hashimoto's thyroiditis: effects of high doses of antithyroid drugs on thyroid autoantibody levels.

We studied the effects of high doses of methimazole (MMI) or propylthiouracil (PTU) on thyroid-stimulating antibody (TSAb), antithyroid microsomal (MCHA) and antithyroglobulin (TGHA) levels in Graves' disease and Hashimoto's thyroiditis. Thirty Graves' hyperthyroid patients were treated for 14 +/- 8 months (mean +/- SD) with MMI, 60-80 mg daily or PTU, 900-1200 mg daily plus T3, 50-75 micrograms daily. Fifteen Hashimoto's thyroiditis patients (4 of whom hypothyroid) received 100-200 micrograms of T4 daily for 4-8 weeks prior to MMI, 60-90 mg daily or PTU, 900 mg daily for 12-16 weeks. In Graves' disease a decrease (p less than 0.001) in TSAb activity (20/25 patients) was observed: before therapy, 0.424 +/- 0.506 pmoles/mg wet wt and at the end of treatment, 0.189 +/- 0.23 pmoles/mg wet wt. The MCHA titers also fell (18/26 patients) from 1:10,403 +/- 20,197 to 1:3,476 +/- 5,252 (p less than 0.01) and was associated with a decrease in free T4 values (1.23 +/- 0.69 vs. 0.51 +/- 0.36 ng/dl; p less than 0.01). A fall of MCHA titers in T4-treated Hashimoto's thyroiditis patients (1:10,416 +/- 25,576) was found when compared with the value before T4 (1:25,920 +/- 39,973; p less than 0.001). However, the titers of MCHA (1:13,280 +/- 25,992) did not change on MMI or PTU plus T4 treatment. The TGHA titers fell in a single patient. No alterations were observed in serum immunoglobulins. Serum concentrations of the complement factor C'3 remained higher (p less than 0.01) than normal values in both Graves' disease and Hashimoto's thyroiditis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Comparison of effects of high and low dosage regimens of antithyroid drugs in the management of Graves' hyperthyroidism.

We compared the effects of high and low dosages of antithyroid drugs in 113 patients with Graves' hyperthyroidism. The patients were randomly divided into 2 groups. In group A, 65 patients received either methimazole (MMI): 60 +/- 14.5 mg/day (mean +/- SD); range 40-100 mg/day, or propylthiouracil (PTU): 693 +/- 173 mg/day; range 500-1200 mg/day. These high doses were maintained throughout treatment with later addition of 50-75 micrograms T3 daily. Forty eight patients (group B) were treated with lower doses of MMI or PTU without thyroid hormone addition. The maintenance dose of MMI was 13.6 +/- 7 mg/day (range 5-25 mg/day) and that of PTU was 180 +/- 58 mg/day (range 100-300 mg/day). The treatment period was 15.1 +/- 4.2 (range 10-30) months for group A and 13.5 +/- 2.2 (range 12-20) months for group B. Remission occurred in 75.4% patients from group A and in 41.6% patients from group B (P less than 0.001). The mean follow-up was 42 +/- 14 months (17-81 months). The free T4 index (FT4I) in group A remained below the normal range during treatment. The mean FT4I, obtained during the course of treatment, of patients who went into remission from group A was significantly (P less than 0.001) lower than in relapsed patients (4.8 vs. 6.5). Moreover, there was an inverse correlation between mean FT4I and maintenance daily dose of either MMI (r = -0.567; P less than 0.001), or PTU (r = -0.379; P less than 0.01). A fall in microsomal antibody (MCHA) titer occurred mainly in remission patients, and was more significant (P less than 0.05) in group A patients. In contrast, 11 (7 from group B) of the 16 patients with an increase of microsomal antibody levels relapsed. The frequency of negative tests of thyroid-stimulating antibody was higher in group A patients (71%) than in group B (29%) at the end of therapy (P less than 0.01). No correlation was found between thyroid T3 suppressibility and either mean FT4I or thyroid-stimulatory antibody activity during treatment. Our findings show that patients treated with high doses of PTU or MMI throughout treatment have a higher remission rate when compared to those treated with a more conventional regimen. These results support the hypothesis that large antithyroid drug doses may have greater immunosuppressive effects than low dosage regimens. Furthermore, a high dosage regimen could permit the restoration of the immune surveillance mechanisms and, thus, lasting remission of Graves' disease.

Adolescent↗
PubMed1982

Episcleral venous pressure in normotensive and glaucomatous beagles.

Episcleral venous pressure was measured by a noninvasive method with a modified force-displacement transducer in six laboratory-quality normotensive and 12 glaucomatous beagles. The dogs were anesthetized by ketamine-xylazine, acepromazine-ketamine, and halothane. Simultaneous intraocular pressure (IOP) and blood pressure were recorded. The mean episcleral venous pressures in normotensive beagles were 11.4 to 11.6 mm Hg with the three methods of anesthesia; in the glaucomatous beagles the mean episcleral pressures were 10.6 to 12.5 mm Hg. There were no significant differences in episcleral venous pressure (p less than 0.19 and greater) and blood pressure (p less than 0.53 and greater) between the normotensive and glaucomatous beagles. IOP was significantly different between the normotensive and glaucomatous beagles anesthetized with acepromazine-ketamine (mean IOP, 23.4 and 34.2 mm Hg, respectively; p less than 0.02) and halothane (mean IOP, 19.9 and 27.4 mm Hg, respectively; p less than 0.001) but not significant with anesthesia with ketamine-xylazine (mean IOP, 26.0 and 37.8 mm Hg, respectively; p less than 0.12). Episcleral venous pressure is unchanged as the disease progresses in the glaucomatous beagle.

Anesthetics↗