Biomedical subjects

J Sampaio

Publications and source records attributed to J Sampaio.

8 recordsLinked to original sources

PubMed2000

A

A solid state, electronically addressable, bistable [2]catenane-based molecular switching device was fabricated from a single monolayer of the [2]catenane, anchored with phospholipid counterions, and sandwiched between an n-type polycrystalline silicon bottom electrode and a metallic top electrode. The device exhibits hysteretic (bistable) current/voltage characteristics. The switch is opened at +2 volts, closed at -2 volts, and read at approximately 0.1 volt and may be recycled many times under ambient conditions. A mechanochemical mechanism for the action of the switch is presented and shown to be consistent with temperature-dependent measurements of the device operation.

Journal Article↗

PubMed1999

Comparative In Vitro Activities of Moxifloxacin (Bay 12-8039) and Other Antimicrobial Agents Against Respiratory Tract Pathogens in Brazil.

Clinical isolates of respiratory tract pathogens were susceptibility tested against six different antimicrobial agents. The in vitro activity of moxifloxacin was compared with that of levofloxacin, cefaclor, amoxicillin-clavulanate acid, azithromycin and trimethoprim-sulfamethoxazole against 111 isolates, including Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and other species isolated from respiratory tract infections. All isolates were susceptible to moxifloxacin, except for two isolates of Pseudomonas aeruginosa which showed intermediate-resistance (MIC=6µg/mL), and one isolate of Escherichia coli which showed resistance (MIC>32µg/mL). Only moxifloxacin and amoxicillin-clavulanic acid were active against 100% of S. pneumoniae isolates at the suceptible breakpoint (MIC90, 0.25 µg/mL and 0.064 µg/mL respectively). The rank order of the activity among this group of drugs against S. pneumoniae was as follows (% of susceptibility): moxifloxacin = amoxicillin-clavulanic acid (100%) > levofloxacin (97%) > cefaclor (71%) > trimethoprim-sulfamethoxazole (54%) > azithromycin (53%). Except for trimethoprim-sulfamethoxazole, all antimicrobial agents were 100% active against H. influenzae and M. catarrhalis. The fluoroquinolones, moxifloxacin and levofloxacin, were the most potent compounds against these pathogens (MIC(90) 0.032 0.19 µg/mL). These in vitro susceptibility testing data of moxifloxacin support the view that this fluoroquinolone will have an important therapeutic role in the treatment of respiratory tract diseases.

Journal Article↗

PubMed1997

Antimicrobial Susceptibility of Klebsiella pneumoniae Producing Extended-Spectrum beta-lactamase (ESBL) Isolated in Hospitals in Brazil.

The prevalence of klebsiella pneumoniae producing extended-spectrum beta-lactamase (ESBL) has been increasing all over the world. Infections caused by ESBL producing isolates are difficult to detect with current susceptibility tests, and are difficult to treat. ESBLs confer resistance to all currently available beta-lactam, except carbapenems. In addition, ESBL production is usually associated with resistance to other classes of antimicrobial agents such as aminoglycosides and quinolones. The objective of this study was to evaluate the in vitro susceptibility patterns of ESBL producing K pneumoniae isolated in Brazil. Seventy-two strains were tested using E test against 30 antimicrobial agents, including carbapenems, second and third generation cephalosporins, aminoglycosides, quinolones, and some new compounds. The most active compounds (i.e. 100% susceptibility) were meropenem (MIC90, 0.125µg/mL), imipenem (MIC90, 0.25µg/mL), and cefotetan (MIC90, 2µg/mL). Ciprofloxacin (MIC90, 1µg/mL, 94% susceptibility) and cefepime (MIC90, 6µg/mL, 92% susceptibility), were also very active against our collection of ESBL producing K pneumoniae. None of the six aminoglycosides showed good activity against these strains (16% to 41% susceptibility) and only 39% of the isolates were susceptible to piperacillin/tazobactam. The results of our study indicated that the carbapenems are the most active compounds against ESBL producing L pneumoniae in Brazil, and ciprofloxacin remains very active against these strains. Cefotetan and cefepime were also very active against ESBL producing K.pneumoniaein Brazil; however, further studies are necessary to evaluate the role of these cephalosporins in the treatment of infections due to ESBL producing strains.

Journal Article↗

PubMed1997

Comparative in vitro Activity of Meropenem Versus Other Extended-Spectrum Antimicrobial Agents Against 2,085 Clinical Isolates Tested in 13 Brazilian Centers.

Meropenem is a parenteral carbapenem antibacterial agent with a very broad spectrum of antibacterial activity. It is the second agent of its class to become available in Brazil. The in vitro antibacterial activity of meropenem was compared with imipenem and four other antimicrobial agents in a multicenter study. This study involved 13 clinical microbiology laboratories, 10 of which came from 8 Brazilian states. A total of 2,085 clinical isolates consecutively collected between December 1995 and March 1996 were susceptibility tested using the Etest and following the NCCLS procedures. Meropenem inhibited more than 90% of isolates of Enterobacteriaceae at 0.5 µg/mL, except for Citrobacter sp. (1 µg/ml). Generally, meropenem was slightly more active than imipenem against Gram-negative organisms and its spectrum of antimicrobial activity was broader than those of all other drugs tested. Against Pseudomonas aeruginosa, meropenem (MIC50, 0.38 µg/ml) was approximately 8-fold more active than imipenem (MIC 50,3 µg/mL). Imipenem was two-to eight-fold more active than meropenem against some Gram-positive specees oxacillin, including Enterococcus faecalis (MIC 50 of 0.75 µg/mL and 2 µg/mL respectively), oxacillin-susceptible Staphylococcus aureus (MIC 50 of 0.47 &mul;g/mL and 0.094 µg/mL), oxacillin-susceptible Staphylococcus epidermidis (MIC 50 of 0.064 µg/mL and 0.5mg/mL). Against Streptococcus sp. meropenem was slightly more active than imipenem (MIC 50, 0.016 µg/mL). The results of this study may be used to guide empiric therapy in Brazil and indicates that meropenem may have an important role in the treatment of infections caused by multiresistant strains of bacteria.

Journal Article↗

PubMed1997

Cladophialophora bantiana (Previously Cladosporium trichoides): First Report of a Case in Brazil.

Cladophialophora bantiana (Cladosporium trichoides) is a black fungus recorded rarely as a cause of brain abscess. Only 21 cases have been reported in the literature world-wide. We describe the first case seen in Brazil. A 30 year old, previously healthy female, HIV negative, came to the hospital with a clinical diagnosis of brain tumor. After biopsy and culture of the lesion, it was found that she had an abscess due to Cladosporium trichoides. During the following five months, the patient underwent three more surgical brain interventions to totally remove the area of compromised tissue. In addition to surgery, amphotericin B, both intravenously and intrathecally, was used followed by itraconazole orally, without success. Six months after the first surgical intervention, the patient died. The worldwide experience with diagnosis and treatment of patients with this diseases is reviewed.

Journal Article↗

PubMed1993

[Cyclosporin A--a therapeutic alternative in giant-cell arteritis?].

Cyclosporine A (CyA) is an immune modulator that may treat immune diseases. The authors present two cases of temporal arteritis treated with CyA; the two patients improved very quickly and after the first six or eight weeks of treatment there were no clinical or laboratory signs of inflammation. As to adverse effects there was a moderate increase in serum creatinine and arterial pressure levels which were controlled when the CyA dosage was reduced. In view of the good results achieved in these two patients, the authors concluded that CyA may be an alternative therapy for giant-cell arteritis and that this hypothesis should be further investigated in a larger group of patients.

Adrenal Cortex Hormones↗

PubMedDate not supplied

[In vitro antimicrobial activity of cefpirome compared to other broad-spectrum beta-lactam drugs against 804 clinical isolates from 9 Brazilian hospitals].

OBJECTIVE: To evaluate the in vitro activity of the fourth-generation cephalosporin cefpirome in comparison to that of ceftazidime, ceftriaxone, cefotaxime and imipenem in a multicenter study involving nine hospitals from six cities (four States). MATERIAL AND METHOD: A total of 804 isolates from patients hospitalized in either intensive care units or Oncology/Hematology units was evaluated. The isolates were collected between June and November of 1995, i.e. before cefpirome became commercially available in Brazil, and susceptibility tested by broth microdilution following the NCCLS procedures. All isolates resistant to cefpirome were retested by E-test. RESULTS: Against Enterobacteriaceae (n = 344), cefpirome demonstrated an activity 2 to 32-fold higher than that of the third-generation cephalosporins (TGCs) and similar to that of imipenem. The percentages of Enterobacteriaceae susceptible were: 88%, 69% and 96% for cefpirome, TGCs and imipenem, respectively. The cefpirome spectrum was greater or equal than that of imipenem against Citrobacter freundii, Enterobacter aerogenes, Morganella morganii and Serratia marcescens. Against Acinetobacter sp. (n = 77), cefpirome was slightly more active than ceftazidime; however, the percentages of isolates resistant to these compounds were high (84% and 88%, respectively). The activities of cefpirome, ceftazidime and imipenem were very similar against P. aeruginosa isolates (n = 128), with MIC50(mg/ml)/percent susceptible of 8/59%, 8/62% and 4/62% respectively. Against aerobic gram-positive bacteria, the cefpirome activity was 4 to 16-fold higher than that of TGCs but 2 to 8-fold lower than that of imipenem. CONCLUSION: The results suggest that, in Brazil, cefpirome has a spectrum of activity which is higher than that of the TGCs against aerobic gram-negative (Enterobacteriaceae and non-Enterobacteriaceae) and gram-positive bacteria and similar to that of imipenem against some Enterobacteriaceae species and P. aeruginosa.

Anti-Bacterial Agents↗

PubMedDate not supplied

[Essential thrombocythemia. Therapy with interferon alfa].

A clinical case of essential thrombocythaemia is presented to demonstrate good therapeutic response to subcutaneous Alpha-2b Interferon in a dosage of 3 x 10(6) units, three times a week. Based on this case and on a literature research we propose that Alpha-2b Interferon is a legitimate alternative to alkylating agents or radioactive phosphorus (32P), showing identical efficacy and less Leukemogen effect.

Female↗