Adult tuberculosis in the 21st century: pathogenesis, clinical features, and management

This article reviews the significant advances in the past year in the basic and clinical aspects of adult tuberculosis (TB). Further research has deepened our understanding of host susceptibility and resistance mechanisms, including cytotoxicity, apoptosis, and antimicrobial polypeptides such as granulysin. Studies have confirmed the effects of HIV infection on risk of disease and disease manifestations, and have defined the effects of HIV on TB transmission. Recent studies also indicate a possible role for extended treatment of active disease and latent infection in HIV-1 infected individuals. Multidrug-resistant disease has been reported on every continent; rapid molecular approaches to the simultaneous diagnosis of TB and detection of rifampin resistance may facilitate prompt initiation of treatment. TB remains one of the major problems in global health.

Comparative in vitro activity of gemifloxacin, ciprofloxacin, levofloxacin and ofloxacin in a North American surveillance study

The in vitro activity of gemifloxacin, a new fluoroquinolone, was compared to three marketed fluoroquinolones; ciprofloxacin, levofloxacin and ofloxacin against over 4,000 recent clinical isolates covering 29 species isolated in the United States and Canada between 1997-1999. Based on MIC(90)s, gemifloxacin was the most potent fluoroquinolone tested against a majority of Gram-positive isolates: Streptococcus pneumoniae, penicillin resistant S. pneumoniae, macrolide resistant S. pneumoniae, ciprofloxacin non-susceptible (MIC > or = 4 microg/mL) S. pneumoniae, S. pyogenes, S. agalactiae, viridans streptococci, Enterococcus faecalis, methicillin susceptible Staphylococcus aureus, methicillin resistant S. aureus, S. epidermidis, S. hemolyticus, and S. saprophyticus. Against Enterobacteriaceae and aerobic non-Enterobacteriaceae Gram-negatives, gemifloxacin was usually comparable to ciprofloxacin and levofloxacin and more potent than ofloxacin for the following species: Citrobacter freundii, Enterobacter aerogenes, E. cloacae, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Morganella morganii, Proteus mirabilis, P. vulgaris, Providencia stuartii, Serratia marcescens, Acinetobacter lwoffii, A. baumannii, Burkholderia cepacia, Haemophilus influenzae, H. parainfluenzae, Moraxella catarrhalis, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia. Gemifloxacin was generally 16-64 fold more potent than the other fluoroquinolones tested against Gram-positive organisms and retains excellent activity comparable with ciprofloxacin and levofloxacin against a majority of Gram-negative pathogens.

Infection and disease among household contacts of patients with multidrug-resistant tuberculosis

SETTING

Urban public teaching and referral hospital in Espirito Santo, Brazil.

OBJECTIVE

To assess whether rates of infection and progression to active tuberculosis (TB) differed between household contacts of patients with multidrug-resistant (MDR) and drug susceptible (DS) pulmonary tuberculosis.

DESIGN

Household contacts were assessed for evidence of TB infection and disease by purified protein derivative (PPD) skin testing, physical examination, chest X-ray, and sputum smear and culture.

RESULTS

Among 133 close contacts of patients with MDR-TB, 44% were PPD-positive (> or =10 mm) compared to 37% of 231 contacts of the DS-TB cases (P = 0.18, chi2 test, OR 1.2, 95%CI 0.8-2). In a multivariate logistic regression analysis, after allowance for between-household variation in PPD responses, PPD positivity among household contacts of patients with MDR-TB remained comparable to PPD positivity in contacts of patients with DS-TB (OR 2.1, 95%CI 0.7-6.5). Respectively six (4%) and 11 (4%) contacts of the MDR- and DS-TB cases were found to have active TB at the time of initial evaluation or during follow-up (P = 0.78, chi2 test). Five of six contacts of MDR-TB cases and nine of nine contacts of DS-TB cases who developed TB, and for whom drug susceptibility test results were available, had the same bacterial susceptibility profiles as their index cases. DNA fingerprinting analysis of Mycobacterium tuberculosis isolates was identical between household contacts with active TB and the index MDR or DS-TB case for all 14 pairs compared.

CONCLUSION

Our data suggest that the prevalence of tuberculous infection and progression to active TB among household contacts exposed to DS and MDR-TB cases is comparable, despite a longer duration of exposure of contacts to the index case in patients with MDR-TB.

Macro-porosity is necessary for the reduction of neointimal and medial thickening by external stenting of porcine saphenous vein bypass grafts

BACKGROUND

placing external non-restrictive macro-porous stents around porcine vein grafts prevents neointima formation and medial thickening in both the short and long term. Whether the porosity of the stent material influences this effect, however, has not been determined. Therefore, the effect on neointimal and medial thickening of external macro-porous (polyester) and micro-porous (polytetrafluorethylene) stents of equal diameter were compared. The effect on expression of platelet-derived growth factor (PDGF), a potent mediator of vascular smooth muscle cell migration and proliferation and its receptors was also investigated.

METHODS AND RESULTS

saphenous vein-carotid artery interposition grafting was performed in Landrace pigs with external placement of 8 mm diameter macro- and micro-porous stents contralaterally. One month after surgery, graft wall dimensions, PDGF and PDGF receptor expression and cell proliferation using proliferating cell nuclear antigen (PCNA) were measured on histological sections. Macro-porous stents significantly reduced neointimal and medial thickening compared with micro-porous stents (0.1+/-0.02 vs. 0.25+/-0.03 mm, P<0.002, and 0.10+/-0.02 vs. 0.17+/-0.02 mm, P<0.014, respectively). Macro-porous stents significantly reduced the percentage of cells expressing PDGF and PCNA, compared with micro-porous stents (36+/-9 vs. 80+/-7, P < 0.002, and 11+/-3 vs. 21+/-2, P < 0.02, respectively). The percentage of cells expressing PDGF receptors was similar with both the stent types. Adventitial microvessel formation occurred across macro-porous stents but was markedly suppressed by micro-porous stents.

CONCLUSIONS

porosity is crucial to the efficacy of external stents in reducing neointima formation in porcine vein grafts. Decreases in PDGF expression and cell proliferation accompany the reduction in neointima formation. In addition, macro-porous stents allow adventitial microvessels to connect with the vasculature outside the stent, thereby potentially improving oxygenation. Although external stenting is highly effective in reducing neointima formation after vein grafting, the properties of the stent material necessary for this effect have not been defined. This study establishes that macro-porosity is one essential feature required to reduce PDGF expression cell proliferation and neointima formation.

Inhibition of isoniazid-induced expression of Mycobacterium tuberculosis antigen 85 in sputum: potential surrogate marker in tuberculosis chemotherapy trials

Mycobacterium tuberculosis antigen 85 is induced in vitro by isoniazid (INH); its sustained induction in sputum during tuberculosis (TB) therapy predicts relapse. In this trial, rifampin or rifalazil inhibited the induction of sputum antigen 85 by INH in a dose-dependent fashion. This approach may facilitate the evaluation of new TB drugs.

HIV-1-related pleural tuberculosis: elevated production of IFN-gamma, but failure of immunity to Mycobacterium tuberculosis

BACKGROUND

Pleural tuberculosis can resolve spontaneously, suggesting that the inflammatory process may represent a protective immune response. However, pleural tuberculosis is strongly associated with HIV infection. It has been suggested that cell-mediated immune responses may be reduced, and direct bacterial invasion may have a role in pathogenesis, in HIV-positive cases. To test this hypothesis, we compared production of the pro-inflammatory cytokines, interferon (IFN)-gamma and tumour necrosis factor(TNF)-alpha, production of the immunosuppressive cytokine, interleukin (IL)-10, and mycobacterial culture positivity, in HIV-negative and HIV-positive patients with pleural tuberculosis.

METHODS

Cytokine levels were measured in serum and pleural fluid, and in supernatants of blood and pleural fluid stimulated in vitro using mycobacterial antigens. Intracellular IFN-gamma and TNF-alpha production was measured after stimulation with phorbol myristate acetate and ionomycin in vitro.

RESULTS

IFN-gamma was strikingly elevated in serum and pleural fluid in HIV-positive, compared to HIV-negative subjects (P < or = 0.02). TNF-alpha was elevated, but this was not statistically significant. IL-10 levels were higher in serum (P < 0.001), but similar in pleural fluid. IFN-gamma responses to soluble mycobacterial antigen in vitro were reduced in peripheral blood (P = 0.006), but not pleural fluid, of HIV-positive subjects. Intracellular cytokine staining suggested that CD8+ T cells were a major source of IFN-gamma in HIV-positive subjects. The proportion of subjects with a positive culture for Mycobacterium tuberculosis from pleural fluid was higher in the HIV-positive group.

CONCLUSIONS

HIV-positive patients with pleural tuberculosis show elevated production of IFN-gamma, for which CD8+ T cells may be a major source. Mycobacterium tuberculosis can proliferate despite high levels of pro-inflammatory cytokines.

Augmentation of apoptosis and interferon-gamma production at sites of active Mycobacterium tuberculosis infection in human tuberculosis

Pleural tuberculosis (TB) was employed as a model to study T cell apoptosis at sites of active Mycobacterium tuberculosis (MTB) infection in human immunodeficiency virus (HIV)-coinfected (HIV/TB) patients and patients infected with TB alone. Apoptosis in blood and in pleural fluid mononuclear cells and cytokine immunoreactivities in plasma and in pleural fluid were evaluated. T cells were expanded at the site of MTB infection, irrespective of HIV status. Apoptosis of CD4 and non-CD4 T cells in the pleural space occurred in both HIV/TB and TB. Interferon (IFN)-gamma levels were increased in pleural fluid, compared with plasma. Spontaneous apoptosis correlated with specific loss of MTB-reactive, IFN-gamma-producing pleural T cells. Immunoreactivities of molecules potentially involved in apoptosis, such as tumor necrosis factor-alpha, Fas-ligand, and Fas, were increased in pleural fluid, compared with plasma. These data suggest that continued exposure of immunoreactive cells to MTB at sites of infection may initiate a vicious cycle in which immune activation and loss of antigen-responsive T cells occur concomitantly, thus favoring persistence of MTB infection.

Resuscitation with a blood substitute abrogates pathologic postinjury neutrophil cytotoxic function

BACKGROUND

Resuscitation with oxygen-carrying fluids is critically important in the patient with hemorrhagic shock caused by trauma. However, it is clear that a number of biologic mediators present in stored blood (packed red blood cells [PRBCs]) have the potential to exacerbate early postinjury hyperinflammation and multiple organ failure through priming of circulating neutrophils (PMNs). PolyHeme (Northfield Laboratories, Evanston, IL), a hemoglobin-based substitute that is free of priming agents, provides an alternative. We hypothesized that PMN priming would be attenuated in patients resuscitated with PolyHeme in lieu of stored blood.

METHODS

Injured patients requiring urgent transfusion were given either PolyHeme (up to 20 units) or PRBCs. Early postinjury PMN priming was measured via beta-2 integrin expression, superoxide production, and elastase release.

RESULTS

Treatment groups were comparable with respect to extent of injury and early physiologic compromise. PMNs from patients resuscitated with PRBCs showed priming in the early postinjury period by all three measures. No such priming was evident in patients resuscitated with PolyHeme.

CONCLUSION

The use of a blood substitute in the early postinjury period avoids PMN priming and may thereby provide an avenue to decrease the incidence or severity of postinjury multiple organ failure.

Atherosclerotic plaque rupture in the apolipoprotein E knockout mouse

The rupture of an atherosclerotic plaque is the main underlying cause of coronary artery thrombotic occlusion and subsequent myocardial infarction, but research into the causes and treatment of plaque rupture is hampered by the lack of a suitable animal model. Although complex atherosclerotic plaques can be induced in a number of experimental animal systems, in none of these is plaque rupture an established feature. We have surveyed branch points in the carotid arteries and aortas of apolipoprotein E knockout mice fed a diet supplemented with 21% lard and 0.15% cholesterol for up to 14 months. Six male and five female mice were used. Four of the male mice and four of the female mice died, after 46+/-3 weeks of feeding (range 37-59 weeks). Lumenal thrombus associated with atherosclerotic plaque rupture was observed in three male and all four female mice. In six of these seven mice, an atherosclerotic plaque rupture was found where the brachiocephalic artery branches into the right common carotid and right subclavian arteries. The ruptures were characterised by fragmentation and loss of elastin in the fibrous caps of relatively small and lipid-rich plaques overlying large complex lesions, with intraplaque haemorrhage. Immunocytochemical analysis revealed loss of smooth muscle cells from ruptured caps. These data suggest that long-term fat-feeding of apolipoprotein E knockout mice is a useful and reproducible model of atherosclerotic plaque rupture, and that these ruptures occur predominantly in the brachiocephalic artery.

Removal of an intrathoracic migrated fixation pin by thoracoscopy

Migration of orthopedic fixation pins into the thoracic cavity can result in perforation of pulmonary vasculature, aorta, bronchus, atrium, or ventricle. Prompt diagnosis and treatment is tantamount in preventing devastating consequences. A patient who had fixation of a right humeral fracture weeks later had intrathoracic migration of a fixation pin, found by routine postoperative radiographic examination. Because the patient was asymptomatic, we removed the pin with a thoracoscopic operation. The foreign body was retrieved successfully without intraoperative or postoperative complication.

Evidence for a two-electron transfer using the all-ferrous Fe protein during nitrogenase catalysis

The nitrogenase-catalyzed H(2) evolution and acetylene-reduction reactions using Ti(III) and dithionite (DT) as reductants were examined and compared under a variety of conditions. Ti(III) is known to make the all-ferrous Fe protein ([Fe(4)S(4)](0)) and lowers the amount of ATP hydrolyzed during nitrogenase catalysis by approximately 2-fold. Here we further investigate this behavior and present results consistent with the Fe protein in the [Fe(4)S(4)](0) redox state transferring two electrons ([Fe(4)S(4)](2+)/[Fe(4)S(4)](0)) per MoFe protein interaction using Ti(III) but transferring only one electron ([Fe(4)S(4)](2+)/[Fe(4)S(4)](1+)) using DT. MoFe protein specific activity was measured as a function of Fe:MoFe protein ratio for both a one- and a two-electron transfer reaction, and nearly identical curves were obtained. However, Fe protein specific activity curves as a function of MoFe:Fe protein ratio showed two distinct reactivity patterns. With DT as reductant, typical MoFe inhibition curves were obtained for operation of the [Fe(4)S(4)](2+)/[Fe(4)S(4)](1+) redox couple, but with Ti(III) as reductant the [Fe(4)S(4)](2+)/[Fe(4)S(4)](0) redox couple was functional and MoFe inhibition was not observed at high MoFe:Fe protein ratios. With Ti(III) as reductant, nitrogenase catalysis produced hyperbolic curves, yielding a V(max) for the Fe protein specific activity of about 3200 nmol of H(2) min(-1) mg(-1) Fe protein, significantly higher than for reactions conducted with DT as reductant. Lag phase experiments (Hageman, R. V., and Burris, R. H. (1978) Proc. Natl. Acad. Sci. U. S. A. 75, 2699-2702) were carried out at MoFe:Fe protein ratios of 100 and 300 using both DT and Ti(III). A lag phase was observed for DT but, with Ti(III) product formation, began immediately and remained linear for over 30 min. Activity measurements using Av-Cp heterologous crosses were examined using both DT and Ti(III) as reductants to compare the reactivity of the [Fe(4)S(4)](2+)/[Fe(4)S(4)](1+) and [Fe(4)S(4)](2+)/[Fe(4)S(4)](0) redox couples and both were inactive. The results are discussed in terms of the Fe protein transferring two electrons per MoFe protein encounter using the [Fe(4)S(4)](2+)/[Fe(4)S(4)](0) redox couple with Ti(III) as reductant.

Demonstrations of the influence of the eating environment on food acceptance

In two independent demonstrations, pre-prepared food was served in different environments: first, identical prepared meals were served in both a training restaurant and in a student cafeteria; second, a prepared main dish was served in a food science laboratory class, and as part of an entire meal in two student cafeterias and in a training restaurant. In the training restaurants and in the student cafeterias, people selected and paid for their meals. The acceptability ratings of the food served varied across the three different environments in the following order: restaurant>laboratory>cafeteria. Differences in acceptance were attributed to contextual effects and the expectations they produce, actual product differences, and a number of possible covariates. Ratings of sensory attributes tended to mirror the acceptability effects. The difficulty of comparing contexts within actual food service systems is discussed.

Analysis of steady state Fe and MoFe protein interactions during nitrogenase catalysis

Steady state kinetic measurements are reported for nitrogenase from Azotobacter vinelandii (Av) and Clostridium pasteurianum (Cp) under a variety of conditions, using dithionite as reductant. The specific activities of Av1 and Cp1 are determined as functions of Av2:Av1 and Cp2:Cp1, respectively, at component protein ratios from 0.4 to 50, and conform to a simple hyperbolic rate law for the interaction of Av2 with Av1 and Cp2 with Cp1. The specific activities of Av2 and Cp2 are also measured as a function of increasing Av1 and Cp1 concentrations, producing 'MoFe inhibition' at large MoFe:Fe ratios. When the rate of product formation under MoFe inhibited conditions is re-plotted as increasing Av2:Av1 or Cp2:Cp1 ratios, sigmoidal kinetic behavior is observed, suggesting that the rate constants in the Thorneley and Lowe (T&L) model are more dependent upon the oxidation level of MoFe protein than previously suspected [R.N.F. Thorneley, D.J. Lowe, Biochem. J. 224 (1984) 887-894], at least when applied to Av and Cp. Calculation of Hill coefficients gave values of 1.7-1.9, suggesting a highly cooperative Fe-MoFe protein interaction in both Av and Cp nitrogenase catalysis. The T&L model lacks analytical solutions [R.N.F. Thorneley, D.J. Lowe, Biochem. J. 215 (1983) 393-404], so the ease of its application to experimental data is limited. To facilitate the study of steady state kinetic data for H(2) evolution, analytical equations are derived from a different mechanism for nitrogenase activity, similar to that of Bergersen and Turner [Biochem. J. 131 (1973) 61-75]. This alternative cooperative model assumes that two Fe proteins interact with one MoFe protein active site. The derived rate laws for this mechanism were fitted to the observed sigmoidal behavior for low Fe:MoFe ratios (<0.4), as well as to the commonly observed hyperbolic behavior for high values of Fe:MoFe for both Av and Cp.

Mechanistic interpretation of the dilution effect for Azotobacter vinelandii and Clostridium pasteurianum nitrogenase catalysis

Nitrogenase activity for Clostridium pasteurianum (Cp) at a Cp2:Cp1 ratio of 1.0 and Azotobacter vinelandii (Av) at Av2:Av1 protein ratios (R) of 1, 4 and 10 is determined as a function of increasing MoFe protein concentration from 0.01 to 5 microM. The rates of ethylene and hydrogen evolution for these ratios and concentrations were measured to determine the effect of extreme dilution on nitrogenase activity. The experimental results show three distinct types of kinetic behavior: (1) a finite intercept along the concentration axis (approximately 0.05 microM MoFe); (2) a non-linear increase in the rate of product formation with increasing protein concentration (approximately 0.2 microM MoFe) and (3) a limiting linear rate of product formation at high protein concentrations (>0.4 microM MoFe). The data are fitted using the following rate equation derived from a mechanism for which two Fe proteins interact cooperatively with a single half of the MoFe protein. (see equation) The equation predicts that the cubic dependence in MoFe protein gives rise to the non-linear rate of product formation (the dilution effect) at very low MoFe protein concentrations. The equation also predicts that the rate will vary linearly at high MoFe protein concentrations with increasing MoFe protein concentration. That these limiting predictions are in accord with the experimental results suggests that either two Fe proteins interact cooperatively with a single half of the MoFe protein, or that the rate constants in the Thorneley and Lowe model are more dependent upon the redox state of MoFe protein than previously suspected [R.N. Thornley and D. J. Lowe, Biochem. J. 224 (1984) 887-894]. Previous Klebsiella pneumoniae and Azotobacter chroococcum dilution results were reanalyzed using the above equation. Results from all of these nitrogenases are consistent and suggest that cooperativity is a fundamental kinetic aspect of nitrogenase catalysis.

Enhanced proliferation and differentiation of human articular chondrocytes when seeded at low cell densities in alginate in vitro

Dedifferentiated human articular chondrocytes exhibited a wide variation in their capacity to proliferate and redifferentiate in an alginate suspension culture system. The greatest extent of proliferation and redifferentiation was seen to be dependent on the formation of clonal populations of chondrocytes and correlated inversely with the initial cell seeding density. Redifferentiating chondrocytes seeded at low density (1 x 10(4) cells/ml alginate) compared with chondrocytes that were seeded at high density (1 x 10(6) cells/ml alginate) showed a nearly 3-fold higher median increase in cell number. a 19-fold greater level of type-II collagen mRNA expression, a 4-fold greater level of aggrecan mRNA expression, and a 6-fold greater level of sulfated glycosaminoglycan deposition at 4 weeks of culture. Matrix molecules from low-density cultures were assembled into chondrocyte-encapsulated, spherical extracellular matrices that were readily visualized in sections from 12-week cultures stained with antibodies against types I and II collagen and aggrecan. Ultrastructural analysis of 12-week low-density cultures confirmed the presence of thin collagen fibrils throughout the matrix.

Efficacy of an unsupervised 8-month rifampicin-containing regimen for the treatment of pulmonary tuberculosis in HIV-infected adults. Uganda-Case Western Reserve University Research Collaboration

SETTING

National Tuberculosis Treatment Centre, Mulago Hospital, Kampala, Uganda.

OBJECTIVE

To assess the efficacy of a daily, self-administered 8-month rifampicin-containing regimen for the treatment of pulmonary tuberculosis (TB) in human immunodeficiency virus (HIV) infected adults.

DESIGN

Treatment outcomes in patients with pulmonary TB treated with a single 8-month regimen and followed in a prospective epidemiological study.

RESULTS

Two hundred and sixty-five HIV-infected and 26 non-HIV-infected adults with initial episodes of pulmonary tuberculosis were treated with 2 months of daily isoniazid (INH), rifampicin (RMP), ethambutol and pyrazinamide followed by 6 months of daily INH + RMP. Median follow-up was 17.8 months. Ninety-five per cent of the HIV-infected and all of the non-HIV-infected patients who had sputum examined were sputum culture negative after 2 months of treatment. Twenty-two HIV-infected and no non-HIV-infected patients died during treatment. Relapse rates were 8.4% (5.9 per 100 person-years of observation [PYO], 95%CI 3.2-8.6) among HIV-infected patients and 4.5% (2.1/100 PYO, 95%CI 0-7.8) for non-HIV-infected patients. Adverse drug reactions occurred in 37% of the HIV-infected patients; most were minor and self-limiting.

CONCLUSION

An 8-month RMP-containing regimen was well tolerated and effective in the treatment of HIV-infected adults with initial episodes of pulmonary TB. Relapse rates were similar to those reported with 6-month short-course regimens in HIV-infected individuals. Decisions about the duration of anti-tuberculosis treatment for HIV-infected adults must balance programme resources and the likelihood of poor compliance with longer regimens with the potential for a modest decrease in relapses with longer treatment.

Slowly resolving and nonresolving pneumonia. Questions to ask when response is delayed

What is the proper course of action when pneumonia symptoms seem to linger? Is the disease running a typical course, or is further evaluation needed? Dr Johnson addresses these important questions with an outline of risk factors for delayed resolution and a detailed listing of diagnostic considerations. He also discusses reasonable timing of further studies and the usefulness of radiography and fiberoptic bronchoscopy.

Simultaneous comparison of reactivity to purified protein derivative RT-23 and Tubersol in health care workers in Vitória, Brazil

Questions have recently been raised regarding the potency of purified protein derivative (PPD) RT-23, the tuberculin most widely used world-wide for skin testing. We performed simultaneous testing with PPD RT-23 and Tubersol to compare these reagents during a tuberculin survey of 202 adult health care workers at a large teaching hospital in 1997. Individuals were tested with 2 tuberculin units (TU) PPD RT-23 and 5 TU Tubersol using the Mantoux method. Using a 10 mm cut-point for a positive PPD test, 39% of the health care workers were positive when tested with Tubersol and 35% were positive when tested with PPD RT-23. The median PPD size with Tubersol was 4 mm (interquartile range = 0-12 mm) compared to 2 mm (interquartile range = 0-12 mm) with PPD RT-23. PPD skin test reactivity with the two reagents was highly correlated (Spearman's rank coefficient, rho = 0.92; P = 0.01, two tailed). Concordance between the skin test reaction size with the two antigens did not differ based on age, sex or prior BCG vaccination. Mantoux skin test reactivity in health care workers in an area with a high prevalence of tuberculosis was comparable with PPD RT-23 and Tubersol.

A comparative In vitro surveillance study of gemifloxacin activities against 2,632 recent Streptococcus pneumoniae isolates from across Europe, North America, and South America. The Gemifloxacin Surveillance Study Research Group

From 1997 to 1999, 94 study centers in 15 European, 3 North American, and 2 South American countries contributed 2,632 isolates of Streptococcus pneumoniae to an international antimicrobial susceptibility testing study. Only 62.0% of isolates were susceptible to penicillin, while 22.3% were penicillin intermediate and 15.6% were penicillin resistant. Resistance to trimethoprim-sulfamethoxazole (24.4%), azithromycin (26.0%), and clarithromycin (27.1%) was also highly prevalent. For the penicillin-resistant isolates (n = 411), the MICs at which 90% of isolates are inhibited (MIC(90)s) for gemifloxacin, levofloxacin, ofloxacin, clarithromycin, and azithromycin were 0.03, 1, 2, >16, and >64 microgram/ml, respectively. Similarly, for isolates resistant to both azithromycin and clarithromycin (n = 649), gemifloxacin, levofloxacin, ofloxacin, and penicillin MIC(90)s were 0.03, 1, 2, and 4 microgram/ml, respectively. Overall rates of resistance to trovafloxacin (0.3%), levofloxacin (0.3%), grepafloxacin (0.6%), and ofloxacin (0.7%) were low. For ofloxacin-intermediate and -resistant isolates (n = 142), gemifloxacin had the lowest MIC(90) (0.12 microgram/ml) compared to the MIC(90)s of trovafloxacin (0.5 microgram/ml), grepafloxacin (1 microgram/ml), and levofloxacin (2 microgram/ml). For all S. pneumoniae isolates tested, gemifloxacin MICs were </=0.5 microgram/ml, suggesting that gemifloxacin has the potential to be used as a treatment for pneumococcal infections, including those arising from isolates resistant to beta-lactams and macrolides.

Quadrupole radiation from terahertz dipole antennas

We report what is to our knowledge the first detailed investigation of the polarization state of radiation from lens-coupled terahertz dipole antennas. The radiation exhibits a weak but measurable component that is polarized orthogonally to the orientation of the emitter dipole. The angular radiation pattern of this cross-polarized emission reveals that it is quadrupolar, rather than dipolar, in nature. One can understand this result by taking into account the photocurrent flowing in the strip lines that feed the dipole antenna. A Fresnel-Kirchhoff scalar diffraction calculation is used for calculating the frequency-dependent angular distribution of the radiation pattern, providing satisfactory agreement with the measurements.

Abdominal perfusion pressure: a superior parameter in the assessment of intra-abdominal hypertension

OBJECTIVE

To assess the clinical utility of abdominal perfusion pressure (mean arterial pressure minus intra-abdominal pressure) as both a resuscitative endpoint and predictor of survival in patients with intra-abdominal hypertension.

METHODS

144 surgical patients treated for intra-abdominal hypertension between May 1997 and June 1999 were retrospectively reviewed. Multivariate logistic regression and receiver operating characteristic curve analysis of common physiologic variables and resuscitation endpoints were performed to determine the decision thresholds for each variable that predict patient survival.

RESULTS

Abdominal perfusion pressure was statistically superior to both mean arterial pressure and intravesicular pressure in predicting patient survival from intra-abdominal hypertension and abdominal compartment syndrome. Multiple regression analysis demonstrated that abdominal perfusion pressure was also superior to other common resuscitation endpoints, including arterial pH, base deficit, arterial lactate, and hourly urinary output.

CONCLUSION

Abdominal perfusion pressure appears to be a clinically useful resuscitation endpoint and predictor of patient survival during treatment for intra-abdominal hypertension and abdominal compartment syndrome.

Serial causation: occasion setting in a causal induction task

The temporal relations among candidate causes were studied in a causal induction task using a design that is known to produce occasion setting in animal learning preparations. For some subset of the observations, one event, the occasion setter, was accompanied by another event, the conditional cause; for another subset of the observations, the conditional cause occurred alone. The efficacy of the conditional cause depended on whether it was or was not accompanied by the occasion setter. Participants used the occasion setter to modulate their effect expectancy to the conditional cause when the events were presented serially, but not simultaneously. Current causal induction models are unable to account for the full range of effects that we observed; the relative roles of time, attention, and cue distinctiveness are discussed.

An unusual case of corneal perforation secondary to Pseudomonas keratitis complicating a patient's surgical/trauma intensive care unit stay

We report a case of corneal perforation secondary to bacterial keratitis caused by Pseudomonas aeruginosa in a trauma patient in our intensive care unit. A 43-year-old man was involved in a motorcycle crash and suffered multiple injuries necessitating a prolonged intensive care unit (ICU) stay. Subsequently P. aeruginosa was cultured from his sputum, blood, and open abdomen. He developed a bacterial keratitis in his right eye, which also grew P. aeruginosa. This infection rapidly progressed to corneal perforation requiring a Gunderson conjunctival flap and lateral tarsorrhaphy in addition to aggressive antibiotic treatment. At the time of discharge from the hospital the patient had the return of vision to light only in his right eye. Corneal perforation is an unusual event in the ICU. Prevention or early detection of bacterial keratitis with aggressive antibiotic treatment is needed to prevent such complications. Pseudomonas is one of the more virulent organisms that can infect the cornea and early identification is paramount for a good outcome. Management of this complicated case is discussed and the limited amount of literature on nosocomial bacterial keratitis in the ICU is reviewed.

Subungual melanoma. A review of 93 cases with identification of prognostic variables

From 1970 to 1996, 93 patients received diagnoses of subungual melanoma. Followup data were complete on all patients and reviewed with a median duration of followup of 5.2 years. This study identifies significant clinicopathologic variables that affect survival and provides the orthopaedic surgeon assistance in the early diagnosis and treatment of this lesion. Eight-three percent of patients presented with Stage I disease, whereas 17% had nodal or distant disease. Fifty-three percent had locally advanced disease at presentation. Twelve percent of the patients were African-American. Fifty-five percent of the lesions arose on the hands with thumb involvement predominating in more than half of these cases. Operative therapy consisted of amputation. Elective lymph node dissection was performed in 34 patients (37%) for Stage I tumors of intermediate thickness. Therapeutic node dissection was required in 16 patients (17%) for positive nodes. Five-year survival was 74% for patients with Stage I disease and 40% for patients with Stage II disease. Statistical analysis identified stage at diagnosis, Clark and Wihm's level, the patient's race, and the presence of ulceration as prognostic variables affecting survival. The diagnosis of subungual melanoma carries a grave prognosis and often is misdiagnosed in the early stages. The treatment of choice is amputation at the appropriate level.

Phase II study of infusional chemotherapy with doxorubicin, vincristine and etoposide plus cyclophosphamide and prednisone (I-CHOPE) in resistant diffuse aggressive non-Hodgkin's lymphoma: CALGB 9255. Cancer and Leukemia Group B

BACKGROUND

Patients with resistant diffuse aggressive non-Hodgkin's lymphoma (DA-NHL) have a poor prognosis. Studies have suggested infusional therapy may be beneficial.

PATIENTS AND METHODS

This trial used an infusional regimen called I-CHOPE in resistant patients who had previously received only bolus CHOPE or CHOP regimen. Resistance was defined as: a) primary refractory disease, b) progression on therapy, c) partial response, d) complete remission lasting less than one year. Eligibility criteria included a diagnosis of DA-NHL (IWF E-H), no prior irradiation and adequate organ function.

RESULTS

Thirty-seven patients were entered and twenty-nine were eligible. Reasons for ineligibility were incorrect histology (5) and other (3). The median age was 57 years (range 29-81) with 21 males. The performance status scores were: 0 (12 patients); 1 (9 patients); 2 (8 patients). Prior therapy consisted of standard CHOP (26 patients), bolus CHOPE (2 patients), high dose CHOP (1 patient). Therapy consisted of a 120 hour continuous intravenous infusion of doxorubicin 10 mg/m2/day, vincristine 0.28 mg/m2/day (maximum 0.4 mg/day), and etoposide 48 mg/m2/day. Cyclophosphamide 750 mg/m2 was given as an i.v. bolus day 6 and prednisone was given at 100 mg/day p.o. on days 1-5. G-CSF was allowed for myelosuppression. The overall response rate was 48% (CR 17%; PR 31%). Freedom from progression was 24% at six months and 8% at one year. Survival was 69% at six months and 40% at one year. In an exploratory analysis a prior CR or PR predicted response to I-CHOPE. Twelve of sixteen patients who had a CR/PR on previous therapy responded while two of thirteen who had no prior response, responded to I-CHOPE (P = 0.003). The toxicity was tolerable with grade 3-4 hematologic toxicity being leucopenia 94% and thrombocytopenia 41%. The grade 3-4 non-hematologic toxicities were infection in 28%, phlebitis in 11%, and stomatitis in 15%.

CONCLUSIONS

I-CHOPE can induce responses in this group of patients with a poor prognosis, but most were seen in those who had previously had a response to bolus chemotherapy.

Long-term satisfaction and psychological and social function following bilateral prophylactic mastectomy

CONTEXT

Prophylactic mastectomy is a preventive option for women who wish to reduce their risk of breast cancer. There has been concern about possible negative psychological sequelae following this procedure. However, few data are available regarding long-term satisfaction and psychological and social function following this procedure.

OBJECTIVE

To evaluate patients' long-term satisfaction and psychological and social function following prophylactic mastectomy.

DESIGN, SETTING, AND PARTICIPANTS

Descriptive study of all women known to be alive (n = 609) who had a family history of breast cancer and elected to undergo bilateral prophylactic mastectomy at a large, tertiary US health care clinic between 1960 and 1993, 94% (n = 572) of whom completed a study questionnaire.

MAIN OUTCOME MEASURES

Satisfaction with procedure and effects on psychological and social function, based on responses to the study-specific questionnaire.

RESULTS

Mean time from prophylactic mastectomy to last follow-up was 14.5 years. Most women (70%) were satisfied with the procedure; 11% were neutral; and 19% were dissatisfied. Among the psychological and social variables, the most striking finding was that 74% reported a diminished level of emotional concern about developing breast cancer. The majority of women reported no change/favorable effects in levels of emotional stability (68%/23%), level of stress (58%/28%), self-esteem (69%/13%), sexual relationships (73%/4%), and feelings of femininity (67%/8%). Forty-eight percent reported no change in their level of satisfaction with body appearance; 16% reported favorable effects. However, 9%, 14%, 18%, 23%, 25%, and 36% reported negative effects in these 6 variables, respectively.

CONCLUSIONS

This study suggests that positive outcomes following prophylactic mastectomy include decreased emotional concern about developing breast cancer and generally favorable psychological and social outcomes. These must be weighed against the irreversibility of the decision, potential problems with implants and reconstructive surgery, and occurrence of adverse psychological and social outcomes in some women. JAMA. 2000;284:319-324

Impact of pulmonary tuberculosis on survival of HIV-infected adults: a prospective epidemiologic study in Uganda

BACKGROUND

Retrospective cohort studies of tuberculosis suggest that active tuberculosis accelerates the progression of HIV infection. The validity of these findings has been questioned because of their retrospective design, diverse study populations, variable compliance with anti-tuberculous therapy and use of anti-retroviral medication. To assess the impact of tuberculosis on survival in HIV infection we performed a prospective study among HIV-infected Ugandan adults with and without tuberculosis.

METHODS

In a prospective cohort study, 230 patients with HIV-associated tuberculosis and 442 HIV-infected subjects without tuberculosis were followed for a mean duration of 19 months for survival. To assess changes in viral load over 1 year, 20 pairs of tuberculosis cases and controls were selected and matched according to baseline CD4 lymphocyte count, age, sex and tuberculin skin test status.

RESULTS

During the follow-up period, 63 out of of 230 tuberculosis cases (28%) died compared with 85 out of 442 controls (19%), with a crude risk ratio of 1.4 [95% confidence interval (CI), 1.07-1.87]. Most deaths occurred in patients with CD4 lymphocyte counts < 200 x 10(6) cells/l at baseline (n = 99) and occurred with similar frequency in the tuberculosis cases (46%) and the controls (44%). When the CD4 lymphocyte count was > 200 x 10(6)/l, however, the relative risk of death in HIV-associated tuberculosis was 2.1 (95% CI, 1.27-3.62) compared with subjects without tuberculosis. For subjects with a CD4 lymphocyte count > 200 x 10(6)/l, the 1-year survival proportion was slightly lower in the cases than in the controls (0.91 versus 0.96), but by 2 years the survival proportion was significantly lower in the cases than in the controls (0.84 versus 0.91; P < 0.02; log-rank test). For subjects with a CD4 lymphocyte count of 200 x 10(6) cells/l or fewer, the survival proportion at 1 year for the controls was lower than cases (0.59 versus 0.64), but this difference was not statistically significant (P = 0.53; logrank test). After adjusting for age, sex, tuberculin skin test status, CD4 lymphocyte count, and history of HIV-related infections, the overall relative hazard for death associated with tuberculosis was 1.81 (95% CI, 1.24-2.65). In a nested Cox regression model, the relative hazard for death was 3.0 (95% CI, 1.62-5.63) for subjects with CD4 lymphocyte counts > 200 x 10(6)/l and 1.5 (95% CI, 0.99-2.40) for subjects with a CD4 lymphocyte count of 200 x 10(6)/l or fewer.

CONCLUSION

The findings from this prospective study indicate that active tuberculosis exerts its greatest effect on survival in the early stages of HIV infection, when there is a reserve capacity of the host immune response. These observations provide a theoretical basis for the treatment of latent tuberculous infection in HIV-infected persons.

Quantitative sputum bacillary load during rifampin-containing short course chemotherapy in human immunodeficiency virus-infected and non-infected adults with pulmonary tuberculosis

SETTING

National Tuberculosis (TB) Treatment Centre, Mulago Hospital and Joint Clinical Research Centre, Kampala, Uganda.

OBJECTIVE

To compare the quantitative sputum bacillary load between TB patients infected with the human immunodeficiency virus (HIV) and those non-infected, during treatment with standard short course chemotherapy (SCC).

DESIGN

To compare clinical characteristics and quantitative sputum bacillary load as measured by quantitative acid-fast bacilli (AFB) smears, colony forming unit (cfu) assay and time until positive culture in the BACTEC radiometric liquid system between 14 HIV-infected and 22 non-HIV-infected adults with initial episodes of smear-positive pulmonary TB at baseline and during treatment with standard four-drug SCC.

RESULTS

Other than cavitation (P = 0.042) and adenopathy (P = 0.03), which were more common among non-HIV-infected and HIV-infected patients, respectively, there were no significant differences in baseline demographic, clinical, radiological and laboratory characteristics between the groups. Mean pretreatment sputum bacillary burden (6.5+/-0.51 log10 AFB/ml, 5.91+/-0.91 log10 cfu/ml and 1.8+/-1.7 days until positive BACTEC culture for HIV-infected patients and 6.32+/-0.85 log10 AFB/ml, 5.58+/-0.68 log10 cfu/ml and 1+/-1.2 days until positive BACTC culture for non-HIV-infected patients) were comparable between HIV-infected and non-HIV-infected patients. Clinical and bacteriological responses to standard SCC and treatment outcome did not differ between the groups.

CONCLUSION

Quantitative sputum bacillary load at baseline and during SCC did not differ significantly between HIV-infected and non-HIV-infected adults with initial episodes of smear-positive TB.

Four earplugs in search of a rating system

OBJECTIVE

The performance of four insert earplugs was evaluated by determining the Noise Reduction Rating (NRR) and the Subject-Fit Noise Reduction Rating [NRR(SF)]. The NRR and NRR(SF) were calculated from real-ear attenuation at threshold (REAT) data collected using the experimenter-fit protocol described in the now-rescinded ANSI S3.19-1974 (American National Standards Institute, 1974) and the subject-fit protocol of the recently revised ANSI S12.6-1997 (American National Standards Institute, 1997) standards for REAT measurement.

DESIGN

A comparison of the experimenter-fit and subject-fit REAT performance was conducted using four pools of subjects, one pool per protector. Each device was tested with at least 20 subjects, the minimum size necessary to estimate the NRR(SF) for an earplug. The REAT was measured with third-octave narrowband noise stimuli for center frequencies at 0.125, 0.25,0.5, 1, 2, 3.15, 4, 6.3, and 8 kHz. The REAT means and standard deviations were compared with the manufacturer data.

RESULTS

This study showed that the NRR(SF) is typically lower than the NRR and that the NRR(SF) is not well-predicted by the NRR derating schemes recommended by the National Institute for Occupational Safety and Health and required by the Occupational Safety and Health Administration.

CONCLUSION

The difference between the present NRR on hearing protector labels and the NRR(SF) is sufficiently large and unpredictable enough to render the application of derating schemes meaningless even though these schemes attempt to account for the difference between the laboratory and real-world outcomes. The only way to provide a protector noise rating that is predictive of a real-world outcome is to retest the protector according to the subject-fit method of ANSI S12.6-1997 (American National Standards Institute, 1997).

Adult tuberculosis overview: African versus Western perspectives

Tuberculosis is currently an enormous global health problem. In industrialized countries in Western Europe and North America, tuberculosis case rates are low and an increasing proportion of cases now occur in foreign-born individuals and in marginalized populations, including the homeless, prisoners, drug users, and persons with human immunodeficiency virus (HIV) infection or acquired immunodeficiency syndrome (AIDS). In contrast, the burden of tuberculosis in sub-Saharan Africa continues to grow, largely fueled by the HIV pandemic and poor public health infrastructure. Use of the World Health Organization's (WHO) directly observed therapy, short course (DOTS) strategy has been successful in improving outcomes and preventing the emergence of acquired drug resistance in several African countries; however, case rates are increasing throughout most of the region. It is clear that control of tuberculosis in Africa is closely linked to control of HIV and AIDS. Substantial external donor support and innovative approaches to enhance interactions between HIV/AIDS prevention and treatment efforts and tuberculosis control programs will be needed to improve the current tuberculosis situation in Africa. The purpose of this review is to provide a synopsis of recent developments in these areas and to serve as a reference source for interested readers.

A role for the Hsp40 Ydj1 in repression of basal steroid receptor activity in yeast

In addition to its roles in translocation of preproteins across membranes, Ydj1 facilitates the maturation of Hsp90 substrates, including mammalian steroid receptors, which activate transcription in yeast in a hormone-dependent manner. To better understand Ydj1's function, we have constructed and analyzed an array of Ydj1 mutants in vivo. Both the glucocorticoid receptor and the estrogen receptor exhibited elevated activity in the absence of hormone in all ydj1 mutant strains, indicating a strict requirement for Ydj1 activity in hormonal control. Glucocorticoid receptor containing a mutation in the carboxy-terminal transcriptional activation domain, AF-2, retained elevated basal activity, while mutation of the amino-terminal transactivation domain, AF-1, eliminated the elevated basal activity observed in ydj1 mutant strains. This result indicates that the source of activity is AF-1, which is normally repressed by the carboxy-terminal hormone binding domain in the absence of hormone. Chimeric proteins containing the hormone binding domain of the estrogen or glucocorticoid receptor fused to heterologous activation and DNA binding domains also exhibited elevated activity in the absence of hormone. Thus, Ydj1 mutants appear to increase basal receptor activity by altering the ability of the hormone binding domain of the receptor to repress nearby activation domains. We propose that Ydj1 functions to present steroid receptors to the Hsp90 pathway for folding and hormonal control. In the presence of Ydj1 mutants that fail to bind substrate efficiently, some receptor escapes the Hsp90 pathway, resulting in constitutive activity.

Positive and negative patterning in human causal learning

Investigations of patterning discriminations by nonhuman animals have generally found that positive patterning is easier to learn than negative patterning. Studies of patterning discriminations in human causal learning tasks have failed to document any differences between positive and negative patterning. In the present study, human participants predicted an outcome on trials involving either a compound cue or its elements. Positive and negative patterning problems were successfully solved in a within-subjects design; negative patterning problems proved to be more difficult when an additional, 50% contingent cue was included (Experiment 2), but not when it was excluded (Experiment 1). Possible reasons for these results are discussed. The discussion concludes with an analysis of exemplar models (e.g., Pearce, 1994) of human causal learning and considers the conditions under which these models do and do not anticipate our results.

Predicting the outcome of therapy for pulmonary tuberculosis

Patients vary considerably in their response to treatment of pulmonary tuberculosis. Although several studies have indicated that adverse outcomes are more likely in those patients with delayed sputum sterilization, few tools are available to identify those patients prospectively. In this study, multivariate models were developed to predict the response to therapy in a prospectively recruited cohort of 42 HIV-uninfected subjects with drug-sensitive tuberculosis. The cohort included 2 subjects whose initial response was followed by drug-sensitive relapse. The total duration of culture positivity was best predicted by a model that included sputum M. tuberculosis antigen 85 concentration on Day 14 of therapy, days-to-positive in BACTEC on Day 30, and the baseline radiographic extent of disease (R = 0.63). A model in which quantitative AFB microscopy replaced BACTEC also performed adequately (R = 0.58). Both models predicted delayed clearance of bacilli in both relapses (> 85th percentile of all subjects) using information collected during the first month of therapy. Stratification of patients according to anticipated response to therapy may allow TB treatment to be individualized, potentially offering superior outcomes and greater efficiency in resource utilization, and aiding in the conduct of clinical trials.

Narratives of smoking relapse: the stories of postpartum women

Many women who stop smoking during pregnancy relapse soon after the birth of their infants. Using narrative research, experiences of smoking relapse were explored using interviews with 27 postpartum women. The stories of relapse were analyzed to identify important components, paying attention to commonalities, differences, and areas of emphasis. Five general story lines were identified: (1) controlling one's smoking (starting with a "puff" and consciously restricting the amount smoked); (2) being vulnerable to smoking(relapsing because of an inability to resist cigarettes); (3) nostalgia for one's former self(relapsing to recapture feelings of freedom and happier times); (4) smoking for relief(relapsing to manage emotions and stress); and (5) never really having quit (relapsing because they did not quit for themselves). The findings of this study provide support for the claim that the experiences of smoking cessation and relapse among postpartum women may be unique and, consequently, may require specialized intervention.

Randomized controlled trial of Mycobacterium vaccae immunotherapy in non-human immunodeficiency virus-infected ugandan adults with newly diagnosed pulmonary tuberculosis. The Uganda-Case Western Reserve University Research Collaboration

Adjunctive immunotherapy with heat-killed Mycobacterium vaccae was studied in a randomized, placebo-controlled trial of 120 non-human immunodeficiency virus-infected adults with newly diagnosed pulmonary tuberculosis. Patients were randomized to a single dose of M. vaccae or placebo 1 week after beginning chemotherapy and were followed up for 1 year. M. vaccae was safe and well tolerated. The rate of sputum culture conversion after 1 month of tuberculosis treatment was 35% in the M. vaccae group and only 14% in the placebo group (P=.01) but was comparable at 2 months and thereafter. Patients receiving M. vaccae had greater improvement on chest radiography at 6 months (91% vs. 77% for placebo recipients; P=.04) and 12 months (94% vs. 80%; P=.04) after initiation of tuberculosis treatment. These data provide evidence of an early increase in sputum culture conversion and greater radiographic improvement among patients who received M. vaccae. Further studies are warranted.

Uncertainty and expectations: taking care of a cardiac surgery patient at home

Family members of postsurgical patients are, by necessity, taking on the caregiving role sooner without any specified resources to help them. The input of these caregivers is essential so nurses can understand their concerns, needs, and struggles and develop strategies to support the caregivers in their caregiving role. This study was designed to increase nursing knowledge regarding the experiences of being a caregiver of a cardiac surgery patient during the immediate postdischarge period. The qualitative research method of Interpretative Description, first described by Thorne, Kirkham, and MacDonald-Emes in 1997 guided the study. In-depth interviews were held with eight spousal caregivers. Findings revealed that the experience was molded by caregivers' past participation as a caregiver, as well as caregivers' and care recipients' outlook on life, their interpersonal relationship, and their expectations. Caregivers engaged in the process of caregiving that involved being vigilant and monitoring the care recipient's recovery, implementing strategies to assist the recovery process, and taking on a role to provide care and seek help as required. The encounter with caregiving affected all realms of caregivers' lives, and they experienced feelings of stress, vulnerability, and having to put their lives on hold; these feelings were often compounded by uncertainty.

Pleural effusions in cardiovascular disease. Pearls for correlating the evidence with the cause

In patients with cardiomegaly and signs and symptoms compatible with CHF, unilateral right-sided or bilateral pleural effusions of similar size are likely to be due to left-sided CHF. Isolated right ventricular failure or chronic pulmonary hypertension is not usually associated with pleural effusions, and unrecognized or new-onset left ventricular dysfunction and other causes should be considered when a patient with cor pulmonale presents with a pleural effusion. Unilateral left-sided pleural effusions with cardiomegaly may be due to pericardial disease. Current hypotheses do not adequately explain the laterality of effusions in CHF or pericardial disease. Clinical and radiographic correlation is always required; however, the associations described occur often enough to make them useful in day-to-day clinical practice. When ascribing pleural effusions to CHF, clinicians must be sure the clinical signs and history "fit the picture," because pneumonia and pulmonary embolism may also cause pleural effusions in patients with heart failure. Typical pleural effusions in patients with uncomplicated CHF (demonstrated by small to medium-sized effusions and the absence of fever, leukocytosis, pleuritic chest pain, or marked asymmetry in bilateral effusions) do not require routine diagnostic thoracentesis for evaluation. A reasonable approach in such cases is treatment of the underlying CHF and follow-up radiography to monitor for resolution of the effusions. Prompt diagnostic thoracentesis is indicated whenever atypical features are present and other diagnoses are under consideration.

Binding of nicotinamide adenine dinucleotide phosphate to the tetratricopeptide repeat domains at the N-terminus of p67PHOX, a subunit of the leukocyte nicotinamide adenine dinucleotide phosphate oxidase

The nicotinamide adenine dinucleotide phosphate (NADPH) binding site of the NADPH oxidase complex is believed to be located on the beta, subunit of cytochrome b558. However, our previous studies showed that p67PHOX also contains an NADPH binding site that is essential for normal oxidase activity and that p67PHOX is able to mediate a slow electron transfer from a reduced pyridine nucleotide to an artificial electron acceptor. Using both affinity labeling and fluorescence quenching, we have obtained further evidence that p67PHOX is able to bind NADPH. We have used a number of truncated forms of p67PHOX, including p67PHOX(1-243), p67PHOX(1-210), p67PHOX(1-199), and p67PHOX(244-526) (where the numbers represent the initial and final amino acids in the truncated p67PHOX) in order to localize the binding site. We found that NADPH could bind to p67PHOX(1-243), p67PHOX(1-210), and p67PHOX(1-199) but not to p67PHOX(244-526). The p67PHOX(1-199) fragment consists largely of four tetratricopeptide (TPR) domains. We showed further that Rac2-GTP gamma S and to a lesser extent Rac2-GDP beta S could modulate the binding of NADPH to p67PHOX.

Primate cytomegaloviruses encode and express an IL-10-like protein

An open reading frame (ORF) with homology to interleukin-10 (IL-10) has been identified in rhesus cytomegalovirus (RhCMV). The IL-10-like protein is generated from a multispliced, polyadenylated early gene transcript encompassing part of the corresponding UL111A ORF of human CMV (HCMV). Immunological analyses confirm expression of the IL-10-like protein both in tissue culture and in RhCMV-infected rhesus macaques. Conserved ORFs were subsequently identified in human, baboon, and African green monkey CMV, and a fully processed transcript has been mapped in fibroblasts infected with the Towne strain of HCMV. The conservation of this previously unrecognized ORF suggests that the protein may play an essential role in primate CMV persistence and pathogenesis.

Analysis of prognosis and disease progression after local recurrence of melanoma

BACKGROUND

Local recurrence of melanoma is associated with a grave prognosis. However, the characteristics and the mode of disease progression for patients with local recurrence have not been adequately addressed in the literature.

METHODS

A retrospective analysis of patients treated at a single institution revealed a subset of patients (n = 648) with local recurrence of melanoma as a first event. Patient characteristics, histologic determinants, and disease free interval were variables used to identify prognostic factors.

RESULTS

In this group of patients, male gender (P = 0. 0163), increasing age (P = 0.0001), head and neck primaries (P = 0. 0001), thicker Breslow depths (P = 0.0022), deeper Clark levels (P = 0.0010), and ulceration of the primary tumor (P = 0.0348) suggested a shorter time until local recurrence. Breslow depth (P = 0.0004), Clark level (P = 0.0043), and ulceration (P = 0.0001) still factored into the survival prognosis after recurrence. Truncal primaries (P = 0.0005) and shorter disease free intervals (P = 0.0098) were also associated with poorer outcomes after recurrence. Of the 648 patients, 124 showed no progression, 196 developed another local recurrence, 178 developed in-transit/lymph node metastases, and 150 had systemic recurrences. Survival was only 33.6% for patients with further metastases, compared with 77.4% for patients with no progression of disease after a median follow-up of 38.9 months.

CONCLUSIONS

There was a 48.5% mortality rate at 5 years of follow-up after local recurrence. Long term survival (> 10 years) was estimated to be 34.9%. The patterns of failure after local recurrence suggest that patients may benefit from aggressive locoregional therapy.

Viral pneumonias. Epidemic respiratory viruses

Influenza, respiratory syncytial, and parainfluenza viruses usually cause mild, self-limited illness in adults. However, elderly and immunocompromised persons are at increased risk for development of severe pneumonia. Clinical and radiographic features of epidemic viral pneumonias are often nonspecific. Newer and faster methods of viral culture and viral antigen detection have improved the capability for definitive diagnosis in recent years. Preventive measures for influenza virus pneumonia center on limiting exposure of high-risk patients to active cases of influenza, administering annual vaccinations, and providing chemoprophylaxis. Prophylaxis against RSV is effective in preventing complications. No effective vaccines have been developed against RSV or parainfluenza. Therapy for viral pneumonia is primarily supportive. Amantadine may be beneficial for influenza virus pneumonia, and ribavirin may be useful for RSV and parainfluenza virus disease. However, further definitive studies are necessary to determine their roles in these viral pneumonias.

Reactions of Azotobacter vinelandii nitrogenase using Ti(III) as reductant

Nitrogenase-catalyzed reactions using Ti(III) were examined under a wide variety of conditions to determine the suitability of Ti(III) to serve as a general nitrogenase reductant. Solutions prepared from H2-reduced TiCl3, aluminum-reduced TiCl3, TiCl2, evaporated TiCl3 from an HCl, solution, and TiF3 were evaluated as reductants. Three general types of reactivity were observed. The first showed that, below Ti(III) concentrations of about 0.50 mM, nitrogenase catalysis utilized Ti(III) in a first-order reaction. The second showed that, above 0.50 mM, the rate of nitrogenase catalysis was zero order in Ti(III), indicating the enzyme was saturated with this reductant. Above 2.0-5.0 mM, nitrogenase catalysis was inhibited by Ti(III) depending on the titanium source used for solution preparation. This inhibition was investigated and found to be independent of the buffer type and pH, while high salt and citrate concentrations caused moderate inhibition. [Ti(IV)] above 2.0-3.0 mM and [Ti(III)] above about 5.0 mM were inhibitory. ATP/2e values were 4-5 for [Ti(III)] at or below 1.0-2.0 mM, 2.0 from 5.0 to 7.0 mM Ti(III) where nitrogenase is not inhibited, and 2.0 above 7.0 mM Ti(III) where severe inhibition occurs. For nitrogenase-catalyzed reactions using Ti(III) as reductant, the potential of the solution changes with time as the Ti(III)/Ti(IV) ratio changes. From the change in the rate of product formation (Ti(III) disappearance) with change in solution potential, the rate of nitrogenase catalysis was determined as a function of solution potential. From such experiments, a midpoint turnover potential of -480 mV was determined for nitrogenase catalysis with an associated n = 2 value.

The association of platelet-derived growth factor receptor expression, plaque morphology and histological features with symptoms in carotid atherosclerosis

Platelet-derived growth factor may influence smooth muscle cell migration and proliferation and, therefore, carotid plaque composition and stenosis. Platelet-derived growth factor receptor expression and histological features were compared in carotid plaques from symptomatic and asymptomatic patients. Immunocytochemistry and histology determined platelet-derived growth factor-alpha and -beta receptor expression, white blood cell infiltration, smooth muscle cell, elastin, cholesterol, collagen and intraplaque haemorrhage in carotid artery plaques removed at surgery or the post-mortem. Plaques with > 70% stenosis from asymptomatic (n = 10) and symptomatic patients (n = 27) had higher expression of platelet-derived growth factor and beta receptors and higher scores for macrophages and intraplaque haemorrhage than plaques with < 70% stenosis from asymptomatic patients (n = 33). Plaques with > 70% stenosis from symptomatic patients had significantly lower alpha receptor expression than plaques with > 70% stenosis from asymptomatic patients. The reduction of alpha receptor expression, which may inhibit smooth muscle cell migration, suggests that differential expression of platelet-derived growth factor receptor subunits in plaques may be related to symptoms.

Maximal human neutrophil priming for superoxide production and elastase release requires p38 mitogen-activated protein kinase activation

HYPOTHESIS

Neutrophil priming has been implicated in the development of multiple organ failure, although the precise intracellular mechanisms that regulate neutrophil priming remain unclear. Our previous work characterized platelet-activating factor (PAF) priming of human neutrophils for concordant superoxide anion (O2-) generation and elastase degranulation. The p38 mitogen-activated protein kinase (MAPK) is activated by PAF stimulation. We hypothesized that PAF-induced human neutrophil priming for O2- and elastase release is mediated via the p38 MAPK pathway.

DESIGN

Isolated neutrophils from 6 human donors were preincubated with the specific p38 MAPK inhibitor SB 203580 (1 micromol/L) or buffer (control) for 30 minutes. Cells were then primed with PAF (200 nmol/L), followed by receptor-dependent (N-formyl-methionyl-leucyl-phenylalanine, 1 micromol/L) or receptor-independent phorbol myristate acetate (PMA, 100 ng/mL) activation.

SETTING

Urban trauma research laboratory.

PATIENTS

Healthy volunteer donors of neutrophils.

MAIN OUTCOME MEASURES

Maximal rate of O2- generation was measured by superoxide dismutase-inhibitable reduction of cytochrome c and elastase release by the cleavage of N-methoxysuccinyl-Ala-Ala-Pro-Val-p-nitroanilide.

RESULTS

SB 203580 significantly attenuated the generation of O2- and release of elastase from neutrophils activated with N-formyl-methionyl-leucyl-phenylalanine but not with PMA. Independent of the activator receptor status, SB 203580 almost completely blocked the exaggerated neutrophil cytotoxic response due to PAF priming.

CONCLUSIONS

The p38 MAPK pathway is required for maximal PAF-induced neutrophil priming for O2- production and elastase degranulation. Therefore, the MAPK signaling cascade may offer a potential therapeutic strategy to preempt global neutrophil hyperactivity rather than attempt to nullify the end products independently.

Determination of drug susceptibility and DNA fingerprint patterns of clinical isolates of Mycobacterium tuberculosis from Kampala, Uganda

OBJECTIVE

To ascertain the rate of initial drug resistance and transmission patterns of Mycobacterium tuberculosis in Kampala, Uganda.

SETTING

National Tuberculosis (TB) Treatment Centre, Mulago Hospital, Kampala, Uganda and Case Western Reserve University, Cleveland, Ohio, USA and McClellan Memorial Veterans Hospital, Little Rock, Arkansas, USA.

METHODS

Using a radiometric BACTEC 460 TB system, susceptibility of 215 M. tuberculosis isolates from previously untreated patients from Kampala, Uganda (age range, 17-48 years, mean, 28 years; 56% males and 69% human immunodeficiency virus (HIV)-seropositive) was determined for isoniazid, rifampin, streptomycin and ethambutol. Isolates from 73 patients, selected on the basis of geographical location, were tested for strain diversity or relatedness using the IS6110 DNA fingerprinting technique.

RESULTS

Resistance rates were as follows: isoniazid, 7.9% streptomycin, 6.1% rifampin, 1.4% and ethambutol 0.9%. Twelve per cent of the strains were resistant to at least one of the first line drugs tested and 4.7% were multiply resistant. There were no significant differences in resistance rates between patients with and without HIV infection. Using the number and size of DNA fragments containing IS6110, only three clusters of isolates with identical RFLP patterns were found out of the 73 isolates tested (8.2%). Each cluster contained two isolates. Three (4.1%) isolates had less than seven copies of IS6110.

CONCLUSION

This study shows that in Uganda initial drug resistance rates to anti-tuberculosis agents are low and similar to other sub-Saharan African countries and that multiple strains of M. tuberculosis have been transmitted within the community.