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Biomedical subjects

J S Tan

Publications and source records attributed to J S Tan.

At least 19 recordsLinked to original sources
PubMed1998

The role of atypical pathogens: Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila in respiratory infection.

Infections caused by M. pneumoniae, C. pneumoniae, and Legionella spp. are important causes of community-acquired pneumonia (CAP). In the past decade, considerable new information has come to light concerning these organisms. Despite this, debate continues concerning the syndromic approach to CAP and the scientific merit of lumping these pathogens together. Because the etiologic diagnosis of these pathogens is established only in a minority of cases, the true prevalence tends to be underestimated. In clinical practice, these pathogens are often empirically treated. More rapid and cost-effective diagnostic techniques are needed so that the clinical course of patients with these infections can be better characterized.

Anti-Bacterial Agents↗
PubMed1997

Human zoonotic infections transmitted by dogs and cats.

Dogs and cats are the 2 most common household pets. However, they may be a direct or indirect source of human infections. This article aims to familiarize physicians with some common and uncommon bacterial, rickettsial, parasitic, and fungal zoonotic infections of dogs and cats. Animal bites with or without infection continue to be a common problem. Treatment of infected animal bites must include early debridement and concern for organisms from the mouth flora of the animal. The diagnosis and treatment of cat-scratch disease have become easier since Bartonella henselae has been established as the main causal agent. Less common bacterial and rickettsial zoonotic infections are included to increase the reader's awareness. Parasitic infections, such as creeping eruptions, visceral larva migrans, cryptosporidiosis, and toxoplasmosis, are diseases associated with contact with dogs and cats. Pets can also be the source of dermatophyte infections. An increase in awareness that some of these diseases may be associated with animals could provide a better plan for the prevention and treatment of common and uncommon zoonotic infections.

Animals↗
PubMed1997

Human alveolar T lymphocyte responses to Mycobacterium tuberculosis antigens: role for CD4+ and CD8+ cytotoxic T cells and relative resistance of alveolar macrophages to lysis.

T cell-mediated cytotoxicity against Mycobacterium tuberculosis (MTB)-infected macrophages may be a major mechanism of specific host defense, but little is known about such activities in the lung. Thus, the capacity of alveolar lymphocyte MTB-specific cell lines (AL) and alveolar macrophages (AM) from tuberculin skin test-positive healthy subjects to serve as CTL and target cells, respectively, in response to MTB (H37Ra) or purified protein derivative (PPD) was investigated. Mycobacterial Ag-pulsed AM were targets of blood CTL activity at E:T ratios of > or = 30:1 (51Cr release assay), but were significantly more resistant to cytotoxicity than autologous blood monocytes. PPD- plus IL-2-expanded AL and blood lymphocytes were cytotoxic for autologous mycobacterium-stimulated monocytes at E:T ratios of > or = 10:1. The CTL activity of lymphocytes expanded with PPD was predominantly class II MHC restricted, whereas the CTL activity of lymphocytes expanded with PPD plus IL-2 was both class I and class II MHC restricted. Both CD4+ and CD8+ T cells were enriched in BL and AL expanded with PPD and IL-2, and both subsets had mycobacterium-specific CTL activity. Such novel cytotoxic responses by CD4+ and CD8+ T cells may be a major mechanism of defense against MTB at the site of disease activity.

Adult↗
PubMed1997

Incidence, etiologic pathogens, and diagnostic testing of community-acquired pneumonia.

Determination of the etiologic pathogens of community-acquired pneumonia has been problematic because of the lack of reliable rapid laboratory diagnostic tools as well as the controversy concerning diagnostic criteria. In the studies reviewed here, a specific pathogen was identified in 39% to 88% of patients. Streptococcus pneumoniae remains the most common cause of community-acquired pneumonia. Depending on the demographics of the study, between 2% to 43% of cases have been attributed to legionella or Chlamydia pneumoniae. More recently, other pathogens have emerged, including respiratory syncytial virus in adults, hantavirus, and possibly legionella-like amoebal pathogens and Streptococcus milleri group. Treatment guidelines published by various societies of experts have been helpful, but they cannot replace the need for better and rapid diagnostic techniques.

AIDS-Related Opportunistic Infections↗
PubMed1997

Hippocampal volumetry with magnetic resonance imaging: a cost-effective validated solution.

PURPOSE: The clinical utility of hippocampal volumetry is well documented, but the materials and techniques required to perform the procedure are not widely available outside major research centers. We describe a personal computer-based method of volumetric data analysis. METHODS: Using a 1.0-T scanner, we obtained 2-mm-thick tilted coronal MPRAGE magnetic resonance imaging (MRI) scans of 20 healthy volunteers aged 20-38 years. We used an inexpensive utility program to extract image information and an NIH Image for image analysis. The hippocampal formations were traced with a graphics tablet and landmarks described by Watson et al. (Neurology 1992;42:1743-50). Overlays of individual observers' tracings were used to fine tune the selection of landmarks and boundaries. Filled-in silhouette pairs generated from these "training tracings" were compared to determine how well observers could visually quantify area differences. RESULTS: Visual detection of asymmetry of silhouette pairs was sensitive, but the magnitude of asymmetry was underestimated. We achieved intraobserver coefficients of variation of right/left volume ratios between 0.82 and 3.16 and an interobserver range of volume ratios of 6%. In 20 healthy controls aged 20-38 years, the mean right and left hippocampal volumes were 2,911 mm3 and 2,836 mm3, respectively. The lower limits of normal were 2,217 mm3 for the right and 2,178 mm3 for the left. The mean right/left hippocampal ratio was 1.03, and the limits of normal (3 SD) for this were 0.95 to 1.10. CONCLUSIONS: Hippocampal volumetry can be performed reliably and economically. Our methodology makes it possible for different observers to generate consistent and comparable measurements.

Adult↗
PubMed1997

Mutagenic synergy between paraoxon and mammalian or plant-activated aromatic amines.

Paraoxon (diethyl-p-nitrophenylphosphate) is the toxic, but non-mutagenic metabolite of the organophosphorus ester (OP) insecticide parathion. Although this agent has been used as a deacetylase inhibitor in many studies, we discovered a mutagenic synergy with paraoxon and plant-activated m-phenylenediamine or with direct-acting 2-acetoxyacetylaminofluorene in Salmonella typhimurium cells [Gichner T et al. (1996): Environ Mol Mutagen 27; 59-66]. In the present study, mammalian-activated m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, benzidine, 2,3-diaminophenazine or 2-aminofluorene, as well as plant-activated benzidine or 2-aminofluorene expressed an elevated mutagenic potency when assayed with S. typhimurium strain YG1024 in the presence of paraoxon. Under non-toxic conditions, paraoxon amplified the S. typhimurium mutant yield induced by these aromatic amines between 1.9-fold and 8.4-fold. Spectrophotometric analysis demonstrated that the rate of degradation of 2-acetoxyacetylaminofluorene was not significantly different in phosphate buffer with or without paraoxon or with S. typhimurium cytosol with or without paraoxon. Also paraoxon-mediated mutagenic synergy does not appear to be due to a direct reaction with aromatic amines. Mutagenic synergy between aromatic amines and OP oxon products may be a cause of concern because people are chronically exposed to environmental and dietary aromatic amines, and a significant segment of the U.S. population tested positive for OP insecticide residues.

Acetoxyacetylaminofluorene↗
PubMed1996

Can aggressive treatment of diabetic foot infections reduce the need for above-ankle amputation?

We retrospectively evaluated the charts of 112 patients with diabetic foot infection to determine if early aggressive surgical intervention improves outcome. All patients were classified into two groups on the basis of the timing of surgical intervention and appropriate antimicrobial therapy. Group I included patients who underwent no surgical intervention during the first 3 days of hospitalization but received intravenous antimicrobial therapy, and group II included patients who underwent surgical intervention promptly and received intravenous antimicrobial therapy. Group II was further divided; group IIA included patients who underwent debridement, and group IIB included patients who underwent local limited amputation. A higher rate of patients in group I than in group II (27.6% vs. 13%, respectively; P < .01) required above-ankle amputation during the same hospitalization or subsequent admission. Overall, an aggressive surgical approach against foot infection in hospitalized diabetic patients reduced the need for above-ankle amputation and the length of hospital stay by at least 6 days. Treatment of diabetic foot infection requires the combination of early surgical treatment and antimicrobial therapy.

Adult↗
PubMed1996

Community-acquired pneumonia. What's needed for accurate diagnosis.

Characteristic clinical findings of fever, cough, and rhonchi, together with a new infiltrate on chest films and documentation of a pathogen, establish a diagnosis of infectious pneumonia. Several factors have had an impact on the approach to diagnosis of community-acquired pneumonia by the primary care physician. These include the expanding number of possible pathogens as well as their increasing resistance to antimicrobial therapy. Although the clinical presentation may suggest a specific cause, findings often overlap too much for reliable identification of the specific agent on clinical grounds alone. Isolation of the microorganism or determination of the presence of a specific antigen or antibody is necessary. However, even after extensive studies are performed, the pathogen remains unidentified in 30% to 50% of cases. The primary care physician therefore needs to balance reasonable use of diagnostic tests with empirical therapy.

Humans↗
PubMed1996

Management of staphylococcal and streptococcal infections.

Staphylococcus and streptococcus are bacteria commonly found on the skin and in the mucous membrane. These bacteria are frequently associated with mild cutaneous infections but may invade to cause deeper infections including necrotizing soft-tissue infections, sepsis with or without metastatic lesions, and immunologic or toxin associated sequelae. Early recognition and timely intervention are the hallmarks of appropriate management. Initial empiric therapy should be directed towards a broad spectrum of pathogens that include staphylococcus and streptococcus.

Anti-Bacterial Agents↗
PubMed1995

Antipseudomonal penicillins.

Antipseudomonal penicillins retain most of the antibacterial activity of penicillin and aminopenicillins. This group of penicillins has added activities against many gram-negative rods, including P. aeruginosa. Similar to the earlier penicillins, this group continues to be susceptible to hydrolysis by many beta-lactamases and are, therefore, not consistently active against Staphylococcus, some gram-negative rods, and certain beta-lactamase-producing gram-negative anaerobes. The ureidopenicillins, especially piperacillin, appear to have better activity against Enterococcus, Klebsiella, and P. aeruginosa than ticarcillin. The advantages over the newer cephalosporins are (1) better activity against Enterococcus, (2) more consistent activity against Clostridium, and (3) more consistent synergy with aminoglycosides. The ureidopenicillins have certain advantages over carboxypenicillins, including lower sodium load, less frequent hypokalemia, reduced platelet dysfunction, minimal dosage adjustment in patients with renal failure, and a wider spectrum of antibacterial activity, especially against Enterococcus, Pseudomonas, and Klebsiella. The utility of the antipseudomonal penicillins by themselves is limited as agents for monotherapy when the infecting organism is not known. In addition, monotherapy is not recommended in certain infections to avoid the development of resistance. When combined with a beta-lactamase inhibitor or with an aminoglycoside, however, some of the weaknesses can be overcome.

Anti-Bacterial Agents↗
PubMed1995

An outbreak of Pseudomonas aeruginosa ventilator-associated respiratory infections due to contaminated food coloring dye--further evidence of the significance of gastric colonization preceding nosocomial pneumonia.

An outbreak of ventilator-associated Pseudomonas aeruginosa respiratory infections in an intensive care unit of a teaching hospital was found to be associated with contaminated food coloring dye. Serotyping and bacteriocin typing indicated that the same strain of Pseudomonas was isolated from the food dye and from the respiratory cultures of the majority of patients. This observation lends credence to the importance of gastric colonization preceding pneumonia in ventilated patients.

Cross Infection↗
PubMed1995

[Therapy of cantharides extract for perennial allergic rhinitis and its effect on total IgE in serum].

The therapy of 10% Cantharides extract in treating 50 cases of perennial allergic rhinitis (PAR) was studied. The extract was plastered and blistered on Dazhui, Neiguan point. It was observed by nasal mucosa provocative test, cells in nasal secretion test and serum total IgE test. The results showed that its effective rate was 88%, the allergic nasal mucosa provocative test of treated group alleviated obviously after the treatment (P < 0.01), the number of eosinophil and basophil in nasal secretion decreased (P < 0.01, P < 0.05); and the serum total IgE also reduced significantly (P < 0.01).

Acupuncture Points↗
PubMed1995

Treatment of skin and soft-tissue infections.

Bacterial infections of the skin range from mild pyodermas to life-threatening necrotizing infections. Pyodermas are most often due to Staphylococcus aureus or beta-hemolytic Streptococcus sp, whereas infections associated with skin ulcers of the extremities, infections following trauma or surgery, and histotoxic necrotizing infections may involve a large number of additional pathogens, including Enterobacteriaceae, Pseudomonas sp, enterococci, and anaerobes. Management of bacterial skin and soft-tissue infections includes appropriate surgical drainage or excision of infected tissue and antimicrobial therapy. The combination of piperacillin and the beta-lactamase inhibitor tazobactam is a newly released antimicrobial, which has excellent in vitro activity against the vast majority of pathogens involved in skin infections. Two multicenter studies recently evaluated the efficacy and safety of piperacillin/tazobactam in the therapy of skin and soft-tissue infections in hospitalized patients. Piperacillin/tazobactam was well tolerated and demonstrated high clinical efficacy for the treatment of these infections.

Bacterial Infections↗
PubMed1994

Hospital medical directors, quality of care, and financial returns.

You are a physician executive working very hard within a hospital on all sorts of medical staff issues and quality of care. You answer to the board. The latter, through its administrators, may still have difficulty documenting the precise value of a full-time physician executive. Your hospital is losing money or not making enough profit for capital expenditures and salary raises. It is considering or will have to consider staff cuts. What can you do that will influence the bottom line, produce a quality image, and quantify your value?

Financial Management, Hospital↗
PubMed1994

Efficacy and safety of piperacillin/tazobactam in skin and soft tissue infections.

Piperacillin/tazobactam has excellent in vitro activity against the most pathogens involved in skin infections. Two large multicentre studies recently evaluated the efficacy and safety of piperacillin/tazobactam in the treatment of skin and soft tissue infections in patients in hospital. The efficacy and safety of piperacillin/tazobactam (4 g/500 mg every 8 hours) have been assessed in an open study in Europe. Among 120 evaluable patients, 93% were clinically cured or improved. Only six patients were withdrawn from the study because of side effects. In another trial, piperacillin/tazobactam were compared with ticarcillin/clavulanate in a double-blinded prospective study in the United States. Of evaluable patients, 67 received piperacillin/tazobactam (3 g/375 mg every 6 hours) and 44 received ticarcillin/clavulanate (3 g/100 mg every 6 hours). At assessment, 76% of patients given piperacillin/tazobactam and 77% of patients given ticarcillin/clavulanate had responded favourably. The lower success rate in this trial may be attributed to more stringent inclusion criteria that resulted in the incorporation of a higher proportion of patients with more severe conditions including diabetic/ischaemic foot infections. The incidence of adverse reactions was similar in both groups. Piperacillin/tazobactam seems to be both effective and safe in the treatment of skin and soft tissue infections in patients confined to hospital.

Bacterial Infections↗