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Previous studies have demonstrated the involvement of complement (C) in induction of efficient CTL responses against different viral infections, but the exact role of complement in this process has not been determined. We now show that C opsonization of retroviral particles enhances the ability of dendritic cells (DCs) to induce CTL responses both in vitro and in vivo. DCs exposed to C-opsonized HIV in vitro were able to stimulate CTLs to elicit antiviral activity significantly better than non-opsonized HIV. Furthermore, experiments using the Friend virus (FV) mouse model illustrated that the enhancing role of complement on DC-mediated CTL induction also occurred in vivo. Our results indicate that complement serves as natural adjuvant for DC-induced expansion and differentiation of specific CTLs against retroviruses.

Several features of HIV have frustrated efforts to develop a vaccine able to induce broadly neutralising antibodies. The enormous genetic diversity of HIV is a major factor, accompanied by the camouflaged nature of the envelope spike, upon which HIV depends for cellular entry and to which antibodies must bind to neutralise. The picture is further complicated by the presence of nonfunctional envelope glycoproteins on the surface of HIV that are immunogenic. Consequently, HIV attracts antibodies that do not directly neutralise the virus but still activate complement and engage Fc receptors, which can both enhance and inhibit infection. The various effects that anti-envelope antibodies have on HIV infection will be reviewed here. Further research is needed to determine if these in vitro-characterised activities have relevance in vivo, and if some of the undesirable effects of non-neutralising antibodies can be avoided or the beneficial effects harnessed.

We describe a pseudo-outbreak of Mycobacterium chelonae infection in bronchoalveolar lavage fluid from 9 patients that was traced to contamination of an automated bronchoscope washer. Molecular typing using repetitive extragenic palindromic polymerase chain reaction was helpful in confirming epidemiologic and clinical findings.

Activation of vascular endothelial growth factor (VEGF) receptor-3 (VEGFR-3) by VEGF-C initiates lymphangiogenesis by promoting lymphatic proliferation and migration. However, it is unclear whether VEGFR-3 signaling is required beyond these initial stages, namely during the organization of new lymphatic endothelial cells (LECs) into functional capillaries. Furthermore, the role of VEGFR-2, which is also expressed on LECs and binds VEGF-C, is unclear. We addressed these questions by selectively neutralizing VEGFR-3 and/or VEGFR-2 for various time periods in an adult model of lymphangiogenesis in regenerating skin. While blocking either VEGFR-2 or VEGFR-3 with specific antagonist mAbs (DC101 and mF4-31C1, respectively) prior to lymphatic migration prevented lymphangiogenesis, blocking VEGFR-3 subsequent to migration did not affect organization into functional capillaries, and VEGFR-2 blocking had only a small hindrance on organization. These findings were confirmed in vitro using human LECs and anti-human antagonist mAbs (IMC-1121a and hF4-3C5): both VEGFR-2 and -3 signaling were required for migration and proliferation, but tubulogenesis in 3D cultures was unaffected by VEGFR-3 blocking and partially hindered by VEGFR-2 blocking. Furthermore, both in vitro and in vivo, while VEGFR-3 blocking had no effect on LEC organization, coneutralization of VEGFR-2, and VEGFR-3 completely prevented lymphatic organization. Our findings demonstrate that cooperative signaling of VEGFR-2 and -3 is necessary for lymphatic migration and proliferation, but VEGFR-3 is redundant with VEGFR-2 for LEC organization into functional capillaries.

The cellular and molecular events underlying the formation and differentiation of mesoderm to derivatives such as blood are critical to our understanding of the development and function of many tissues and organ systems. How different mesodermal populations are set aside to form specific lineages is not well understood. Although previous genetic studies in the mouse embryo have pointed to a critical role for the homeobox gene Mix-like (mMix) in gastrulation, its function in mesoderm development remains unclear. Hematopoietic defects have been identified in differentiating embryonic stem cells in which mMix was genetically inactivated. Here we show that conditional induction of mMix in embryonic stem cell-derived embryoid bodies results in the early activation of mesodermal markers prior to expression of Brachyury/T and acceleration of the mesodermal developmental program. Strikingly, increased numbers of mesodermal, hemangioblastic, and hematopoietic progenitors form in response to premature activation of mMix. Differentiation to primitive (embryonic) and definitive (adult type) blood cells proceeds normally and without an apparent bias in the representation of different hematopoietic cell fates. Therefore, the mouse Mix gene functions early in the recruitment and/or expansion of mesodermal progenitors to the hemangioblastic and hematopoietic lineages.

Highly active anti-retroviral therapy (HAART) has been very effective in reducing viral loads in human immunodeficiency virus (HIV)-1 patients. However, current therapies carry detrimental side effects, require complex drug regimes and are threatened by the emergence of drug-resistant variants. There is an urgent need for new anti-HIV drugs that target different stages of the replication cycle. Several synthetic small organic molecules that inhibit HIV infection by binding to the CCR5 coreceptor without causing cell activation have already been reported. Here, we have exploited a series of CCR5 antagonists to investigate their effects on diverse HIV and the simian counterpart (SIV) isolates for infection of a variety of cell types via different concentrations of cell surface CCR5. These inhibitors show no cross-reactivity against alternative HIV coreceptors including CCR3, CCR8, GPR1, APJ, CXCR4 and CXCR6. They are able to inhibit a diverse range of R5 and R5X4 HIV-1 isolates as well as HIV-2 and SIV strains. Inhibition was observed in cell lines as well as primary PBMCs and macrophages. The extent of inhibition was dependent on cell type and on cell surface CCR5 concentration. Our results underscore the potential of CCR5 inhibitors for clinical development.

Two HIV-1 isolates (CM4 and CM9) able to use alternate HIV-1 coreceptors on transfected cell lines were tested for their sensitivity to inhibitors of HIV-1 entry on primary cells. CM4 was able to use CCR5 and Bob/GPR15 efficiently in transfected cells. The R5 isolate grew in Delta32/Delta32 CCR5 PBMC in the absence or presence of AMD3100, a CXCR4-specific inhibitor, indicating that it uses a receptor other than CCR5 or CXCR4 on primary cells. It was insensitive to the CCR5 entry inhibitors RANTES and PRO140, but was partially inhibited by vMIP-1, a chemokine that binds CCR3, CCR8, GPR15 and CXCR6. The coreceptor used by this isolate on primary cells is currently unknown. CM9 used CCR5, CXCR4, Bob/GPR15, CXCR6, CCR3, and CCR8 on transfected cells and was able to replicate in the absence or presence of AMD3100 in Delta32/Delta32 CCR5 PBMC. It was insensitive to eotaxin, vMIP-1 and I309 when tested individually, but was inhibited completely when vMIP-1 or I309 was combined with AMD3100. Both I309 and vMIP-1 bind CCR8, strongly suggesting that this isolate can use CCR8 on primary cells. Collectively, these data suggest that some HIV-1 isolates can use alternate coreceptors on primary cells, which may have implications for strategies that aim to block viral entry.

We report the first endothelial lineage-specific transgenic mouse allowing live imaging at subcellular resolution. We generated an H2B-EYFP fusion protein which can be used for fluorescent labeling of nucleosomes and used it to specifically label endothelial cells in mice and in differentiating embryonic stem (ES) cells. A fusion cDNA encoding a human histone H2B tagged at its C-terminus with enhanced yellow fluorescent protein (EYFP) was expressed under the control of an Flk1 promoter and intronic enhancer. The Flk1::H2B-EYFP transgenic mice are viable and high levels of chromatin-localized reporter expression are maintained in endothelial cells of developing embryos and in adult animals upon breeding. The onset of fluorescence in differentiating ES cells and in embryos corresponds with the beginning of endothelial cell specification. These transgenic lines permit real-time imaging in normal and pathological vasculogenesis and angiogenesis to track individual cells and mitotic events at a level of detail that is unprecedented in the mouse., ((c) 2005 Wiley-Liss, Inc.)

Purpose: Approximately 5% to 10% of newly diagnosed breast cancer patients carry a BRCA1 or BRCA2 mutation. Given these patients' high risk for contralateral breast cancer, bilateral mastectomy is increasingly considered a treatment option for newly diagnosed BRCA1/2 carriers. In the present study, we prospectively evaluated the impact on surgical decision-making of pretreatment genetic counseling and BRCA1/BRCA2 testing among breast cancer patients at high-risk for carrying a mutation., Patients and Methods: Participants were 194 newly diagnosed breast cancer patients who had not yet received definitive surgical treatment and who had at least a 10% prior probability of carrying a BRCA1/2 mutation. Participants were offered free genetic counseling and rapid BRCA1/2 testing. Primary analyses focused on the impact of BRCA1/2 test result on subsequent breast cancer surgical treatment., Results: Forty-eight percent of patients who were found to carry a BRCA1/2 mutation chose bilateral mastectomy as their definitive breast cancer surgery. In contrast, 24% of patients in whom no mutation was detected and 4% of test decliners opted for bilateral mastectomy. Additional predictors of bilateral mastectomy included patients' self-reports of physician recommendations for BRCA1/2 testing and bilateral mastectomy., Conclusion: This study highlights patient interest in and the technical feasibility of offering presurgery BRCA1/2 testing to high-risk patients. Most importantly, these results demonstrate that BRCA1/2 test results significantly affect patients' surgical decision-making. The availability of genetic counseling and testing could serve as a valuable aid to patient decision-making for newly diagnosed breast cancer patients at high-risk for carrying a mutation.

Objectives: With the use of highly active antiretroviral therapy, the identification of HIV reservoirs within the body has become an important issue. However, the testis has been largely ignored despite representing a pharmacologic sanctuary which could act as a viral reservoir., Design: Because alterations in testosterone production have frequently been reported in HIV-infected individuals, we investigated whether the testosterone-producing Leydig cells could become directly infected by HIV-1, HIV-2 or SIV., Methods: Purified Leydig cells were infected with a panel of HIV-1, HIV-2 and SIV strains and examined for expression of HIV/SIV receptors. Additionally, the impact of CD4 transduction on Leydig cell infection was determined., Results: Leydig cells were unable to support productive infection of the seven HIV-1 isolates tested. No CD4, CXCR4 or CCR5 expression was evident on the surface of Leydig cells and transduction with a CD4 expressing adenovirus did not induce HIV-1 infection. In contrast, some primary and laboratory adapted CD4-independent HIV-2 and SIV strains were able to enter and replicate productively in Leydig cells., Conclusions: Our results suggest that Leydig cells do not represent a target for HIV-1 infection within the testis. In contrast, Leydig cells support HIV-2 and SIV infection and thus represent a potential target for infection. Receptor use and significance of HIV-2/SIV infection of Leydig cells remain to be determined.

Stool specimens in various patient populations were examined to determine isolation rates of Clostridium difficile and the frequency with which this organism produces a cytopathic toxin in vitro. Clostridium difficile was isolated from 13 of 45 healthy neonates who had never received antimicrobials and the cytotoxin was detected in 12. With 23 healthy children aged 4 to 24 mo the organism was recovered from 2 children and the cytotoxin was detected in 1. Neither the organism nor the cytotoxin was found in specimens from healthy adults who denied antimicrobial usage during the prior 4 wk. Clostridium difficile was recovered from 12 of 56 adults receiving antimicrobials without diarrhea, but only one specimen yielded the cytotoxin. Both the cytotoxin and the organism were found in stools from most patients with antibiotic-associated colitis. Concentrations of Clostridium difficile, when present, were similar in all patient populations. Broth cultures of 165 isolates of Clostridium difficile showed all strains, but two produced the cytotoxin in vitro. However, the concentration of the toxin was substantially higher with strains recovered from patients with positive toxin assays. These observations indicate that neonates are often asymptomatic carriers of both Clostridium difficile and its cytotoxin. In adults, gastrointestinal symptoms correlated best with results of tissue culture assays and with toxigenic potential of the strains isolated.

Quantitative aerobic and anaerobic cultures were performed on 28 tracheal aspirates from 16 clinically stable patients with tracheostomies. There were an average of six isolates per specimen, and the mean bacterial concentration was 106.9 organisms per milliliter. The numerically dominant bacteria were aerobic and facultative gramnegative bacilli. Anaerobic bacteria were recovered from just nine specimens (32 percent); and, when present, these organisms were found in relatively low concentrations. Repeat cultures obtained 30 to 60 days later from the same patients showed substantial changes in flora, but the numerically dominant species tended to persist. Cultures of saliva and throat swabs collected at the time of tracheal aspiration showed that there was little correlation between the bacteriologic findings from the upper and lower airways. Cytologic studies indicated a mean of 12,900 cells per cubic millimeter of tracheal aspirate, with polymorphonuclear leukocytes being the predominant forms. No correlation could be found between the concentrations of polymorphonuclear leukocytes and quantitative bacterial counts. These studies indicate that tracheal aspirates from patients with stable tracheostomies harbor a complex, predominantly aerobic flora which is subject to change and bears little relationship to the flora of the adjacent upper airways. Our results also suggest that neither quantitative bacterial cultures nor cytologic analysis of these specimens would be helpful in distinguishing colonization from overt infection requiring antibiotic treatment.

A model was developed to permit direct assessment of antibiotic efficacy against Enterococcus species in experimental intra-abdominal abscess. Abscesses yielded Enterococcus faecalis in pure culture. Antimicrobials were delivered by precisely controlled continuous intravenous infusion. After five days of therapy, ampicillin alone or in combination with gentamicin reduced residual bacterial titers from 7.93 +/- 1.05 (untreated) to 3.51 +/- 1.07 and 3.52 +/- 0.81 log10 colony forming units per gram, respectively. Both the clindamycin and gentamicin combination (6.49 +/- 1.33) and metronidazole and gentamicin combination (6.79 +/- 0.90) significantly suppressed the growth of enterococci (p less than 0.01). Combined clindamycin and aztreonam was ineffective, as were any of the agents used alone (except ampicillin). These results may explain, in part, the clinical efficacy of certain drug combinations against the enterococcal component of polymicrobial abscesses despite the apparent lack of in vitro activity of individual agents.

FFAs are bound with calcium on the albumin molecule. We hypothesized that changes in circulating FFA levels during critical illness altered calcium-albumin binding. We found that serum from both normal subjects and critically ill patients contained an ether-extractable factor which lowered ionized calcium concentrations and increased albumin-calcium binding. This factor was found in higher concentrations in serum from ill patients. Oleic acid and palmitic acid increased albumin-calcium binding from 2-28% in a dose-dependent manner when added in vitro to calcium-albumin solutions. Scatchard analysis demonstrated that 0.1 mM oleic acid increased the number of calcium-binding sites on the albumin molecule (from three to five sites per molecule) without altering binding affinity. A similar effect was found when we performed Scatchard analyses of ether extracts in serum from three critically ill patients (number of calcium-binding sites increased from three to six). We also found that lipid infusions (during parenteral nutrition) lowered mean serum ionized calcium values in six critically ill patients [4.6 +/- 0.2 (+/- SEM) to 4.1 +/- 0.2 mg/dL; P less than 0.05]. These data support the concept that FFAs increase calcium binding to the albumin molecule. Alterations in FFA concentrations during critical illness may contribute to the poor correlation between corrected total serum calcium and ionized calcium concentrations in critically ill patients. In addition, acute elevations in circulating FFA concentrations may contribute to hypocalcemia in patients with defects in bone calcium mobilization.

Naloxone's pressor effects in shock may be mediated through antagonism of endogenous opioid inhibition of sympathoadrenal catecholaminergic systems. Since circulating catecholamine levels are not further elevated by naloxone in endotoxemic animals, it is possible that naloxone acts upon opiate receptors to enhance catecholamine actions at the receptor or postreceptor level. To investigate this hypothesis, we sought to determine whether naloxone treatment would augment the pressor actions of exogenous catecholamines (epinephrine) in normal and endotoxemic rats. Naloxone (3 mg/kg intravenous [i.v.] bolus followed by 3 mg/ml/hr infusion) significantly augmented the pressor response to 10, 20, and 50 micrograms/kg of i.v. epinephrine by 69%, 48% and 14%, respectively, in endotoxin (5 mg/kg, LD20, i.v.) -treated rats but not in normal rats. Likewise, the duration of the pressor response to epinephrine was significantly increased by naloxone. These findings suggest that the coadministration of naloxone and epinephrine may be of benefit in the treatment of shock.

The unique needs of British Isles nurses warrants the nurse educator to design an orientation program that contains specific content and issues common to the American health care system.

The inhibitory effect of lidocaine and lidocaine plus methylparaben as a preservative was studied with 25 strains of bacteria. The tested strains were mixed with each topical anesthetic preparation, and quantitative cultures were performed on aspirates at 0, 30, 60, and 120 minutes. Results were compared to counts obtained in a lactated Ringer's solution, which were sampled at the same intervals. Lidocaine (1 percent solution) reduced quantitative counts after 120 minutes of contact by over one log for only six of the 25 strains tested. Lidocaine plus methylparaben reduced quantitative counts to a somewhat greater extent; nevertheless, all strains except Bacteroides melaninogenicus were recovered in relatively high concentrations at each sampling interval. Numerous previous studies have shown that topical anesthetic agents are toxic to bacteria. The results of this study show that this toxic effect is not sufficiently severe to prevent the recovery of most pathogens of the lower respiratory tract in bronchoscopic aspirates.