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Biomedical subjects

J Nguyen

Publications and source records attributed to J Nguyen.

At least 19 recordsLinked to original sources
PubMed2004

Activity of linezolid against Gram-positive cocci isolated in French hospitals as determined by three in-vitro susceptibility testing methods.

In total, 844 strains of Gram-positive cocci were collected from six university hospitals in France between September 1999 and January 2000. MICs of linezolid were determined: (i) for all strains by agar dilution (method A); (ii) by broth microdilution (method B) for staphylococci and enterococci; (iii) by Etest (method E) for beta-haemolytic streptococci and Streptococcus pneumoniae. Susceptibility to other antibiotics was determined by the disk diffusion method. MIC50 and MIC90 values were identical (2 mg/L) for methicillin-susceptible Staphylococcus aureus (n = 179) by methods A and B. Linezolid was active against methicillin-resistant S. aureus (n = 117), with an MIC90 of 2 mg/L (methods A and B), but with a lower MIC50 of 1 mg/L by method A. Of the 200 coagulase-negative staphylococci, 56.5% were methicillin-resistant and 43.5% were methicillin-susceptible. Linezolid had similar in-vitro activity by methods A and B (MIC50 and MIC90 values of 1-2 mg/L), irrespective of methicillin susceptibility. The MIC90 of linezolid for all enterococci (150 Enterococcus faecalis and 50 Enterococcus faecium) was 2 mg/L by both methods. MICs of linezolid for beta-haemolytic streptococci had a narrow range of 0.5-2 mg/L (method A) and 0.125-2 mg/L (method E). Pneumococci (n = 118), including 67 penicillin G-intermediate and -resistant strains, were all inhibited by linezolid 2 mg/L (MIC90 of 2 mg/L by methods A and E). No strain had an MIC of > 2 mg/L by agar dilution or Etest, or of > 4 mg/L by broth microdilution. Overall, the study confirmed the good in-vitro activity of linezolid and the very narrow range of MICs for Gram-positive cocci susceptible or resistant to other antibiotics, irrespective of the method used.

Acetamides↗
PubMed2003

In vitro antibacterial activity of moxifloxacin against hospital isolates: a multicentre study.

OBJECTIVE: To evaluate the in vitro antibacterial activity of moxifloxacinin in comparison to that of other fluoroquinolones (ciprofloxacin, ofloxacin and trovafloxacin). METHODS: A total of 2,196 strains was collected in 11 French hospitals in 1998. Minimum inhibitory concentrations (MICs) (mg/L) were determined by agar dilution and agar diffusion was performed with 5-microg discs. Internal quality control was carried out with genetically defined strains. RESULTS: MIC50s and MIC90s of moxifloxacin against nalidixic acid (NAL)-susceptible Enterobacteriaceae (n = 663) were 0.12 and 0.5. As for other quinolones, the activity of moxifloxacin (4-32) was reduced against NAL-intermediate and NAL-resistant strains (n = 222). MIC50s and MIC90s of moxifloxacin were 2 and 4 for ciprofloxacin-susceptible P. aeruginosa (n = 128); moxifloxacin had no activity against ciprofloxacin-resistant strains (n = 56). The activity of moxifloxacin was maintained against NAL-susceptible A. baumannii (n = 11; 0.032-0.125), but reduced against NAL-resistant strains (n = 30; 16-32). H. influenzae (n = 97) and M. catarrhalis (n = 40) were inhibited by low concentrations (0.03-0.06 and 0.06-0.25, respectively). Moxifloxacin had better activity (0.06-0.12) than other tested quinolones against methicillin-susceptible S. aureus strains (n = 110); ciprofloxacin-resistant strains (n = 85) (2-8) were usually methicillin-resistant. Moxifloxacin was moderately active against enterococci (n = 149) (E. faecalis: 0.5-16; E. faecium: 2-4). Streptococci (n = 194) and pneumococci (n = 136), including 70 penicillin G-intermediate or G-resistant strains, were inhibited by low concentrations (0.25-0.5 for each species). Based on the regression curve, tentative zone diameter breakpoints could be > or =21 and <18 mm for MIC breakpoints of < or =1 and >2 mg/L, respectively. CONCLUSIONS: While retaining activity against Enterobacteriaceae, moxifloxacin was moderately active against P. aeruginosa. Its activity was inferior to that of ciprofloxacin for these species. This study confirmed the comparatively high in vitro activity of moxifloxacin against Gram-positive cocci and other pathogens isolated from community-acquired respiratory tract infections.

Anti-Infective Agents↗
PubMed2001

[Kwashiorkor after an exclusion diet for eczema].

BACKGROUND: Nutritional disorders observed in children with eczema may be aggravated by inappropriate diet, sometimes with dramatic effects. CASE REPORT: A child aged 3 years 7 months presented a state of severe malnutrition with edema (kwashiorkor). The child had chronic eczema and had been given a highly restrictive diet based on a principle of exclusion without medical advise. Cure was achieved without sequelae with a normal diet. DISCUSSION: This case illustrates the fragility of nutritional status in children with chronic widespread skin disease due to the risk of cutaneous loss of protein. Kwashiorkor is an exceptional observation in developed countries and, in this context, might be on the rise due to the popularity of exclusion diets for presumed allergic disease.

Child, Preschool↗
PubMed2001

Obtaining force-frequency curves with a single 3-second train of stimuli.

We devised a method to assess the force-frequency relationship (FFR) in human skeletal muscle that involved delivery of a single 2.8-s train of shocks directly to the femoral nerve. This increasing-frequency train (IFT) was based on a power function, with a range of stimulation frequencies beginning at 5 Hz and rising to 100 Hz. We compared the IFT to a standard series of constant-frequency trains (CFT) under two conditions. Force-frequency curves were examined, first in response to altered muscle length and second, following fatigue. There was no leftward shift in the curve when the knee extensors were shortened, although maximal force increased. In contrast, we observed a rightward shift in the curve after fatigue with both protocols; the frequency required to develop 50% of maximal force increased by 48% (P <.01) with CFT and 58% (P <.001) with an IFT. The CFT produced an irregular pattern of low-frequency fatigue recovery. In the IFT, low-frequency fatigue was greatest at the onset of recovery and decreased linearly until 120 s. These experiments show that the IFT protocol reveals alterations in muscle performance similar to the more traditional CFT. However, it requires only 2.8 s to administer and was judged more tolerable by 70% of our subjects. This suggests that the IFT may be an effective alternative for determining the FFR in human muscle for clinical and experimental purposes.

Adult↗
PubMed2001

Multicenter evaluation of an automated system using selected bacteria that harbor challenging and clinically relevant mechanisms of resistance to antibiotics.

A multicenter study was carried out to evaluate the performance of a new commercial automated system in comparison with that of the reference agar dilution method. Ten clinical microbiology laboratories tested a collection of 61 strains of gram-negative bacilli (49 Enterobacteriaceae and 12 Pseudomonas aeruginosa), and 6 other laboratories tested a collection of 55 strains of gram-positive cocci (10 enterococci and 45 staphylococci) against 10-20 antimicrobial agents. The strains were selected on the basis that they harbored challenging and characterized mechanisms of resistance. In comparison with the agar reference method, the automated system gave an overall essential agreement (+/-1 dilution) of 94.5%, 93.5%, and 97% for the gram-negative bacilli, enterococci, and staphylococci, respectively. According to the interpretive standards of the National Committee for Clinical Laboratory Standards, the category agreement ranged from 96 to 96.4% for the three sets of organisms. The accuracy of the automated system, as determined by the kappa test, ranged from 0.80 to 0.88, reflecting an almost perfect agreement with the reference technique. Very major, major, and minor errors obtained with the automated system were 0.3%, 2.9%, and 6.6% for gram-negative bacilli, 3.4%, 0%, and 5% for enterococci, and 1%, 1.6%, and 2.7% for staphylococci, respectively. The high rate of very major errors in enterococci was mostly due to a single strain of multidrug-resistant Enterococcus faecium, which was found susceptible to several antibiotics in a majority of participant laboratories. The use of a heavy inoculum and of a broth test medium by the automated system might account for a better expression of certain resistance mechanisms, including beta-lactamases, as compared to the agar dilution reference method. The interlaboratory reproducibility was acceptable, as shown by the narrow dispersion of MICs and by the results of quality control.

Anti-Bacterial Agents↗
PubMed2001

Breast cancer screening among Hmong women in California.

BACKGROUND: Breast cancer is the leading cause of cancer incidence and mortality among Asian American and Pacific Islander (AAPI) women in the United States. Hmong women are among those at the highest risk for health problems, due to high rates of poverty, language isolation, and cultural barriers. METHOD: One-on-one survey interviews were completed with 201 Hmong women aged 20 years and older in Fresno, Long Beach, Orange County, and San Diego to determine their breast cancer screening behaviors--breast self-examination (BSE), clinical breast examination (CBE), and mammography. RESULTS: Overall, 51% of all respondents had ever performed BSE. Among respondents aged 40 or older, 52% had ever had a CBE and only 30% had ever had mammography. DISCUSSION: Significant correlates of CBE and mammography screening are presented, and implications of findings for research and education are discussed.

Adult↗
PubMed2001

In vitro activities of ertapenem (MK-0826) against recent clinical bacteria collected in Europe and Australia.

Ertapenem (MK-0826, L-749,345) is a 1-beta-methyl carbapenem with a long serum half-life. Its in vitro activity was determined by broth microdilution against 3,478 bacteria from 12 centers in Europe and Australia, with imipenem, cefepime, ceftriaxone, and piperacillin-tazobactam used as comparators. Ertapenem was the most active agent tested against members of the family Enterobacteriaceae, with MICs at which 90% of isolates are inhibited (MIC(90)s) of < or =1 microg/ml for all species. Ertapenem also was more active than imipenem against fastidious gram-negative bacteria and Moraxella spp.; on the other hand, ertapenem was slightly less active than imipenem against streptococci, methicillin-susceptible staphylococci, and anaerobes, but its MIC(90)s for these groups remained < or =0.5 microg/ml. Acinetobacter spp. and Pseudomonas aeruginosa were also much less susceptible to ertapenem than imipenem, and most Enterococcus faecalis strains were resistant. Ertapenem resistance, based on a provisional NCCLS MIC breakpoint of > or =16 microg/ml, was seen in only 3 of 1,611 strains of the family Enterobacteriaceae tested, all of them Enterobacter aerogenes. Resistance was also seen in 2 of 135 anaerobes, comprising 1 Bacteroides fragilis strain and 1 Clostridium difficile strain. Ertapenem breakpoints for streptococci have not been established, but an unofficial susceptibility breakpoint of < or =2 microg/ml was adopted for clinical trials to generate corresponding clinical response data for isolates for which MICs were as high as 2 microg/ml. Of 234 Streptococcus pneumoniae strains tested, 2 required ertapenem MICs of 2 microg/ml and one required an MIC of 4 microg/ml, among 67 non-Streptococcus pyogenes, non-Streptococcus pneumoniae streptococci, single isolates required ertapenem MICs of 2 and 16 microg/ml. These streptococci also had diminished susceptibilities to other beta-lactams, including imipenem as well as ertapenem. The Etest and disk diffusion gave susceptibility test results in good agreement with those of the broth microdilution method for ertapenem.

Anti-Bacterial Agents↗
PubMed2000

Lens injury stimulates axon regeneration in the mature rat optic nerve.

In mature mammals, retinal ganglion cells (RGCs) are unable to regenerate their axons after optic nerve injury, and they soon undergo apoptotic cell death. However, a small puncture wound to the lens enhances RGC survival and enables these cells to regenerate their axons into the normally inhibitory environment of the optic nerve. Even when the optic nerve is intact, lens injury stimulates macrophage infiltration into the eye, Müller cell activation, and increased GAP-43 expression in ganglion cells across the entire retina. In contrast, axotomy, either alone or combined with intraocular injections that do not infringe on the lens, causes only a minimal change in GAP-43 expression in RGCs and a minimal activation of the other cell types. Combining nerve injury with lens puncture leads to an eightfold increase in RGC survival and a 100-fold increase in the number of axons regenerating beyond the crush site. Macrophage activation appears to play a key role, because intraocular injections of Zymosan, a yeast cell wall preparation, stimulated monocytes in the absence of lens injury and induced RGCs to regenerate their axons into the distal optic nerve.

Animals↗
PubMed2000

Novel therapeutic nano-particles (lipocores): trapping poorly water soluble compounds.

The development of stable spherical lipid-coated drug particles that are termed 'lipocores' is reported here. Unlike conventional lipid-based particles (i.e. liposomes, emulsions, micelles), these particles are comprised solely of a core of a poorly water soluble drug surrounded by polyethyleneglycol conjugated lipid (PEG-lipid) and are formed via a 'kinetic' trapping process. These lipocore particles were made with the acyl chain of 16 carbon length (C16) acyl-chain derivatives of paclitaxel or vinblastine and with the polyene antifungal hamycin. Formation of the particles occurred regardless of the type of PEG-phospholipid used (i.e. acyl chain length, chain saturation, and polymer length) and could also be formed with the negatively charged lipid N-glutaryl-dioleoyl-phosphatidylethanolamine (DOPE-GA). Images from both freeze-fracture electron microscopy and electron cryo-microscopy revealed solid spherical structures with no internal lamellae for the PEG-lipid particles made with the C16 derivatives of paclitaxel (BrC16-T) or vinblastine (C16-Vin). From a solute distribution study of lipocores made with BrC16-T and distearoyl-phosphatidylethanolamine-PEG2000 (DSPE-PEG2000), the particles were found to have no measurable aqueous captured volume. Fluorescence anisotropy and order parameter measurements revealed the core material of these particles to be highly immobilized. The mole ratio of BrC16-T:lipid in the lipocores was typically > 90: < 10 and as high as 98:2, and the refrigerated lipocores were stable for several months. BrC16-T/DSPE-PEG2000 lipocores of 50-100 nm particle size were far less toxic than paclitaxel (Taxol) after intraperitoneally (i.p.) or intravenously (i.v.) administration in mice and were active against i.p. and subcutaneously (s.c.) planted human (OvCar3) ovarian carcinoma grown in SCID mice. It is believed the high drug:lipid ratio, the stability, and therapeutic efficacy of these novel particles make them a paradigm for delivery of poorly water soluble drugs and/or their hydrophobic derivatives.

Animals↗
PubMed2000

[Endoscopic surgery of third ventricle lesions].

The endoscopic approach of the tumors of the third ventricle interests mainly the colloid cysts but also offers the possibilities of biopsies. Twenty two patients (16 men and 6 women, average age 41 years) presenting with hydrocephalus related to a tumor of the pineal area were treated by a ventriculostomy with attempt at biopsy : they are outside of the limits of this report. Twenty two other patients (15 men, 7 women, average age 39 years) were operated on from 1994 to 1999 for a colloid cyst, and 2 of them were admitted in emergency in sudden coma. The CT scan showed a colloid cyst (hyperdense in 16 patients) associated with an hydrocephalus, except for a patient previously shunted. The diameter of the cyst varied from 4 to 50 mm (average of 20 mm). All the patients were operated on using a rigid endoscope. Among the 20 patients presenting a tumor of the pineal area, a biopsy was possible only in 4 cases (20%). There were no hemorrhage nor neurological disorders. In all the cases, the size and the number of the specimens were sufficient to allow the histological diagnosis. For the patients presenting with colloid cyst, the average follow-up is 2 years. All the preoperative symptoms disappeared except for the memory disorders which were improved. The post-operative Evans index decreased significantly. No residual cyst was observed on the post-operative MRI in 14 patients (63%). Among these patients, an asymptomatic recurrence was observed and remained stable after 44 months of follow-up. A residual cyst was observed in 8 patients (36%), with a diameter from 5 to 25 mm (average 9 mm). No patient required a shunt procedure, and no patient presented hemorrhagic complication. Endoscopy is especially useful in the first line treatment of the colloid cysts of the third ventricle.

Adult↗
PubMed1999

Multiresolution browsing of pathology images using wavelets.

Digitized pathology images typically have very high resolution, making it difficult to display in their entirety on the computer screen and inefficient to transmit over the network for educational purposes. Progressive zooming of pathology images is desirable despite the availability of inexpensive networking bandwidth. An efficient progressive image resolution refining system for on-line distribution of pathology image using wavelets has been developed and is discussed in this paper. The system is practical for real-world applications, pre-processing and coding each 24-bit image of size 2400 x 3600 within 40 seconds on a Pentium II PC. The transmission process is in real-time. Besides its exceptional speed, the algorithm has high flexibility. The server encodes the original pathology images without loss. Based on the image request from a client, the server dynamically generates and sends out the part of the image at the requested scale and quality requirement. The algorithm is expandable for medical image databases such as PACS.

Algorithms↗
PubMed1999

Growth inhibition of a human ovarian tumor by a novel paclitaxel derivative in SCID mice.

We report here the toxicity and therapeutic effects of 2'-alpha-bromohexadecanoyl paclitaxel (BrC16HT), a prodrug form of paclitaxel, in mice. Paclitaxel is the active ingredient of Taxol. The maximum tolerated dose, at a one dose per day for 5-day schedule, was 37.5 mg/kg for BrC16HT compared to 12.5 for Taxol administered IP, and was 12.5-25 mg/kg for either agent administered IV. Dose-dependent therapeutic effects were found for BrC16HT against a human ovarian tumor (OVCAR-3) grown in SCID mice. IP treatments with BrC16HT against early or established IP-implanted OVCAR-3 tumor increased mean survival times more than treatment with Taxol. Long-term survivors were found only in groups treated with BrC16HT. Intravenously administered BrC16HT was more effective than Taxol against SC OVCAR-3 tumor. Early treatment (25 mg/kg x 5) completely inhibited tumor growth through 120 days after tumor implantation. Pharmacokinetic studies suggest that BrC16HT is slowly hydrolyzed to paclitaxel and circulates longer than paclitaxel from Taxol. Thus, BrC16HT may provide sustained levels of paclitaxel, which may contribute to the increased efficacy of BrC16HT compared to Taxol.

Animals↗
PubMed1998

MAGE Xp-2: a member of the MAGE gene family isolated from an expression library using systemic lupus erythematosus sera.

Two regions of the genome contain members of the MAGE gene family; Xq27-qter and Xp21.3. We isolated a transcript, MAGE Xp-2, by screening a cDNA library from the human epithelial carcinoma cell line, HEp-2, using autoantibodies from patients with systemic lupus erythematosus (SLE). The open reading frame (ORF) of MAGE Xp-2 is entirely contained in exon 4, a signature feature of the MAGE gene family. While MAGE Xp-2 shares genomic homology with MAGE Xp-1, the predicted proteins are quite divergent. Specific primers were designed to reliably distinguish between MAGE Xp-1 and MAGE Xp-2 expression. MAGE Xp-2 is expressed in testis, but not in other normal tissues. It is also expressed strongly in two of seven melanoma cell lines and one of four breast carcinomas. MAGE gene expression may be important not only for tumor recognition and cancer therapy, but, because it is the apparent target of autoantibodies in SLE sera, it may also play a role in autoimmune diseases.

Amino Acid Sequence↗
PubMed1998

Pyogenic bacterial pneumonia in human immunodeficiency virus-infected inpatients: a clinical, radiological, microbiological, and epidemiological study.

We prospectively studied features of pyogenic bacterial pneumonia in 263 consecutive human immunodeficiency virus-infected inpatients over a 6-month study period. Risk factors for bacterial pneumonia were examined by a case-control study that included 33 cases who presented with at least one episode of bacterial pneumonia and 80 controls without bacterial pneumonia. The estimated cumulative incidence of bacterial pneumonia per year was 12.5 cases per 100 inpatients (95% confidence interval [CI], 8.8-17.2). The 38 episodes of bacterial pneumonia that occurred in the 33 inpatients were mainly unilateral, but 32 episodes were patchy lobar or diffuse infiltrates. Microbiological etiologies were obtained in 33 of the 38 episodes of bacterial pneumonia. Thirty-seven pathogens were identified, including Streptococcus pneumoniae (16, of which 12 had a decreased susceptibility to penicillin), Haemophilus influenzae (6), and Pseudomonas aeruginosa (6). The risk factors for bacterial pneumonia that were identified after logistic regression included prior sinusitis within 1 month before admission (odds ratio [OR], 3.2; 95% CI, 1.1-9.1) and prior bacterial infection of the lower respiratory tract within 6 months before admission (OR, 3.1; 95% CI, 1.1-8.3).

AIDS-Related Opportunistic Infections↗