Role of lung macrophages on susceptibility to respiratory infection following short-term moderate exercise training

Moderate exercise training is associated with a decreased risk for upper respiratory tract infection in human and animal studies, but the mechanisms have not been elucidated. Lung macrophages play an important role in resistance to respiratory infection, and moderate exercise can enhance macrophage antiviral resistance, but no studies have directly tested the role of lung macrophages in this response. This study tested the effect of lung macrophage depletion on susceptibility to infection following short-term moderate exercise training. Mice were assigned to one of four groups: exercise (Ex) and resting controls (Con) with and without clodronate encapsulated liposomes (CL2MDP-lip). Ex mice ran for 1 h on a treadmill for 6 days at 36 m/min, 8% grade. Fifteen minutes following exercise or rest on the last day of training, mice were intranasally inoculated with a standardized dose of herpes simplex virus type 1. Clodronate (Ex-CL2MDP-lip and Con-CL2MDP-lip) or PBS liposomes (Ex-PBS-lip and Con-PBS-lip) (100 μl) were intranasally administered following exercise or rest on the 4th day of training and again on the 4th day postinfection. Morbidity, mortality, and symptom severity were monitored for 21 days. Exercise decreased morbidity by 36%, mortality by 61%, and symptom severity score on days 5–7 ( P < 0.05). Depletion of lung macrophages negated the beneficial effects of moderate exercise. This was indicated by no differences between Ex-CL2MDP-lip and Con-PBS-lip in morbidity (89 vs. 95%), mortality (79 vs. 95%), or symptom severity. Results indicate that lung macrophages play an important role in mediating the beneficial effects of moderate exercise on susceptibility to respiratory infection.

Effects of moderate exercise and oat β-glucan on lung tumor metastases and macrophage antitumor cytotoxicity

Both moderate exercise and the soluble fiber β-glucan can have beneficial effects on the initiation and growth of tumors, but the data are limited, and there is no information on their combined effects. This study tested the independent and combined effects of short-term moderate-exercise training and the soluble oat fiber β-glucan (OβG) on the metatastic spread of injected tumor cells and macrophage antitumor cytotoxicity. Male C57BL/6 mice were assigned to one of four groups: exercise (Ex)-H2O, Ex-OβG, control (Con)-H2O, or Con-OβG. OβG was fed in the drinking water for 10 days before tumor administration and death. Exercise consisted of treadmill running (1 h/day) for 6 days. After rest or exercise on the last day of training, syngeneic B16 melanoma cells (2 × 105) were administered via intravenous injection ( n = 8–11 per group). Lungs were removed 14 days later, and tumor foci were counted. Additional mice ( n = 8 per group) were killed, and peritoneal macrophages were assayed for cytotoxicity against the same mouse tumor cell line at various effector-to-target ratios. Both moderate exercise and OβG decreased lung tumor foci and increased macrophage cytotoxicity. However, there were no differences in lung tumor foci and macrophage cytotoxicity between Ex-OβG and either Ex-H2O or Con-OβG. These data suggest that, although not additive in their effects, both short-term moderate-exercise training and consumption of the soluble OβG can decrease the metatastic spread of injected B16 melanoma cells, and these effects may be mediated in part by an increase in macrophage cytotoxicity to B16 melanoma.

Effects of moderate exercise and oat β-glucan on innate immune function and susceptibility to respiratory infection

Both moderate exercise and the soluble oat fiber β-glucan can increase immune function and decrease risk of infection, but no information exists on their possible combined effects. This study tested the effects of moderate exercise and oat β-glucan on respiratory infection, macrophage antiviral resistance, and natural killer (NK) cell cytotoxicity. Mice were assigned to four groups: exercise and water, exercise and oat β-glucan, control water, or control oat β-glucan. Oat β-glucan was fed in the drinking water for 10 days before intranasal inoculation of herpes simplex virus type 1 (HSV-1) or euthanasia. Exercise consisted of treadmill running (1 h/day) for 6 days. Macrophage resistance to HSV-1 was increased with both exercise and oat β-glucan, whereas NK cell cytotoxicity was only increased with exercise. Exercise was also associated with a 45 and 38% decrease in morbidity and mortality, respectively. Mortality was also decreased with oat β-glucan, but this effect did not reach statistical significance. No additive effects of exercise and oat β-glucan were found. These data confirm a positive effect of both moderate exercise and oat β-glucan on immune function, but only moderate exercise was associated with a significant reduction in the risk of upper respiratory tract infection in this model.

Immune control of Brucella abortus 2308 infections in BALB/c mice

BALB/c mice infected with Brucella abortus strain 2308 have 10-fold higher levels of bacteria during the plateau phase of infection (the time period when the number of colony-forming units in vivo remains consistent) than the more resistant C57BL/10 mice. This is due to a cessation of interferon-gamma (IFN-gamma) production that begins after the first week of infection and continues until the end of the plateau phase at least 6 weeks post infection. Despite the lack of IFN-gamma production during this time BALB/c mice are able to prevent an increase in bacterial colony-forming units. Here it was shown that both tumor necrosis factor (TNF)-alpha and CD8 T cells were involved in controlling bacterial numbers in BALB/c mice during this time. That is, neutralization of TNF-alpha or depletion of CD8 T cells with monoclonal antibodies resulted in a significant increase in the number of splenic colony-forming units recovered at 3 weeks post infection. In the absence of CD8 T cells there was also a significant increase in splenic macrophages. The role of TNF-alpha may depend upon the presence of interferon-gamma early in the infection since when TNF-alpha was neutralized in interferon-gamma gene knockout mice there was a marked increase in splenic macrophages, NK cells and neutrophils but not a significant increase in colony-forming units.

Development of an effective gene delivery system: a study of complexes composed of a peptide-based amphiphilic DNA compaction agent and phospholipid

We recently described a basic technology to efficiently combine compacted DNA with phospholipids and hydrophobic peptides, to produce homogenous complexes that are completely resistant to nuclease. We have developed this technology further to form gene delivery complexes that transfect cells effectively in vitro. In addition to plasmid DNA, the complexes contained two basic components: (i) a DNA compacting peptide (-CGKKKFKLKH), either conjugated to lipid or extended to contain (WLPLPWGW-) and (ii) either phosphatidylethanolamine or phosphatidylcholine. Complexes containing a 5.5-fold charge equivalence (peptide charge/DNA charge) of WLPLPWGWCGKKKFKLKH and 5 nmol dimyristoleoylphosphatidylethanolamine/microg DNA produced the highest luciferase gene expression, exceeding 1 x 10(9) relative light units/s/mg protein (>3 microg luciferase per mg protein). These complexes transfected OVCAR-3, COS-7 and HeLa cells at either similar or superior levels when compared to polyethylenimine or lipofectamine complexes. With green fluorescent protein reporter gene, >50% of HeLa cells were positive 30 h after addition of these complexes. Furthermore, these optimal complexes were the least sensitive to pre-treatment of cells with chloroquine, indicating efficient endosomal escape. Our results indicated that self-assembling complexes of plasmid DNA, amphiphilic peptide and phosphatidylethanolamine are highly effective non-viral gene delivery systems.

Interferon-gamma is crucial for surviving a Brucella abortus infection in both resistant C57BL/6 and susceptible BALB/c mice

Brucella abortus is an intracellular bacterial pathogen that causes chronic infections in humans and a number of agriculturally important species of animals. It has been shown that BALB/c mice are more susceptible to infections with virulent strains of Brucella abortus than C57BL/6 or C57BL/10 strains. In experiments described here, gene knock-out mice were utilized to elucidate some of the salient components of resistance. Resistant C57BL/6 mice with gene deletions or disruptions in the interferon-gamma (IFN-gamma), perforin or beta(2)-microglobulin genes had decreased abilities to control intracellular infections with B. abortus strain 2308 during the first week after infection. However, only the IFN-gamma knock-out mice had a sustained inability to control infections and this resulted in death of the mice at approximately 6 weeks post-infection. These mice had a continual increase in the number of bacterial colony-forming units (CFU) in their spleens until death. When BALB/c mice with the disrupted IFN-gamma gene were infected they had more splenic CFU at one week post-infection than control mice but the increase was not statistically significant and by 3 weeks they did not have more CFU than control mice. Moreover, the number of splenic bacteria did not increase in the BALB/c IFN-gamma knock-out mice between 6 and 10.5 weeks, although they died at 10.5 weeks, the time by which normal BALB/c mice were clearing the infection. Death in both strains of IFN-gamma gene disrupted mice coincided with symptoms of cachexia and macrophages comprised > or= 75% of the splenic leucocytes.

Compaction of DNA in an anionic micelle environment followed by assembly into phosphatidylcholine liposomes

A difficult problem concerning the interaction of DNA with amphiphiles of opposite charge above their critical micelle concentration is the propensity for aggregation of the condensed DNA complexes. In this study, this problem was addressed by attenuating amphiphile charge density within a cholate micelle environment. The amphiphile consisted of a cationic peptide, acetyl-CWKKKPKK-amide, conjugated to dilaurylphos-phatidylethanolamine. In the presence of cholate, multiple equivalents of cationic charge were required to bring about the completion of DNA condensation. At the end point of condensation, stable, soluble DNA-micelle complexes were formed, which by dynamic light scattering exhibited apparent hydro-dynamic diameters between 30 and 60 nm. Aggregation, as measured by static light scattering at 90 degrees and by turbidity, was not observed until further additions of peptide-lipid conjugate were made beyond the end point of DNA condensation. Liposome complexes containing the non-aggregated, compacted DNA were formed by adding dioleoylphosphatidylcholine followed by removing the cholate by dialysis. The resulting complexes were distributed within a narrow density range, the DNA was quantitatively assembled into the liposomes, and liposomes without DNA were not detected. Small particles were formed with a mean hydrodynamic diameter of 77 nm. The liposomal DNA showed complete retention of its supercoiled form and no detectable sensitivity to DNase (25 U/10 microg DNA, 1.5 h, 37 degrees C). The use of an anionic, dialyzable amphiphile to attenuate charge inter-actions between DNA and cationic amphiphiles is a useful technology for the quantitative assembly of compacted DNA into conventional liposomes, with complete protection against nuclease activity.

The human cytomegalovirus IE86 protein can block cell cycle progression after inducing transition into the S phase of permissive cells

Human cytomegalovirus (HCMV) infection of permissive cells has been reported to induce a cell cycle halt. One or more viral proteins may be involved in halting progression at different stages of the cell cycle. We investigated how HCMV infection, and specifically IE86 protein expression, affects the cell cycles of permissive and nonpermissive cells. We used a recombinant virus that expresses the green fluorescent protein (GFP) to determine the effects of HCMV on the cell cycle of permissive cells. Fluorescence by GFP allowed us to select for only productively infected cells. Replication-defective adenovirus vectors expressing the IE72 or IE86 protein were also used to efficiently transduce 95% or more of the cells. The adenovirus-expressed IE86 protein was determined to be functional by demonstrating negative autoregulation of the major immediate-early promoter and activation of an early viral promoter in the context of the viral genome. To eliminate adenovirus protein effects, plasmids expressing GFP for fluorescent selection of only transfected cells and wild-type IE86 protein or a mutant IE86 protein were tested in permissive and nonpermissive cells. HCMV infection induced the entry of U373 cells into the S phase. All permissive cells infected with HCMV were blocked in cell cycle progression and could not divide. After either transduction or transfection and IE86 protein expression, the number of all permissive or nonpermissive cell types in the S phase increased significantly, but the cells could no longer divide. The IE72 protein did not have a significant effect on the S phase. Since IE86 protein inhibits cell cycle progression, the IE2 gene in a human fibroblast IE86 protein-expressing cell line was sequenced. The IE86 protein in these retrovirus-transduced cells has mutations in a critical region of the viral protein. The locations of the mutations and the function of the IE86 protein in controlling cell cycle progression are discussed.

Mucosal T lymphocyte numbers are selectively reduced in integrin alpha E (CD103)-deficient mice

The mucosal lymphocyte integrin alpha E(CD103)beta 7 is thought to be important for intraepithelial lymphocyte (IEL) localization or function. We cloned the murine integrin gene encoding alpha E, localized it to chromosome 11, and generated integrin alpha E-deficient mice. In alpha E-/- mice, intestinal and vaginal IEL numbers were reduced, consistent with the known binding of alpha E beta 7 to E-cadherin expressed on epithelial cells. However, it was surprising that lamina propria T lymphocyte numbers were diminished, as E-cadherin is not expressed in the lamina propria. In contrast, peribronchial, intrapulmonary, Peyer's patch, and splenic T lymphocyte numbers were not reduced in alpha E-deficient mice. Thus, alpha E beta 7 was important for generating or maintaining the gut and vaginal T lymphocytes located diffusely within the epithelium or lamina propria but not for generating the gut-associated organized lymphoid tissues. Finally, the impact of alpha E deficiency upon intestinal IEL numbers was greater at 3-4 wk of life than in younger animals, and affected the TCR alpha beta+ CD8+ T cells more than the gamma delta T cells or the TCR alpha beta+ CD4+CD8- population. These findings suggest that alpha E beta 7 is involved in the expansion/recruitment of TCR alpha beta+ CD8+ IEL following microbial colonization. Integrin alpha E-deficient mice will provide an important tool for studying the role of alpha E beta 7 and of alpha E beta 7-expressing mucosal T lymphocytes in vivo.

The functional synergy between IL-12 and IL-2 involves p38 mitogen-activated protein kinase and is associated with the augmentation of STAT serine phosphorylation

IL-12 and IL-2 can stimulate mitogen- or CD3-activated T cells to proliferate, produce IFN-gamma, and kill tumor cells. The magnitude of these functional responses is greatly augmented when T cells are activated by the combination of IL-12 and IL-2. Although peripheral blood T cells are largely unresponsive to these cytokines without prior activation, a small subset of CD8+ T cells (CD8+CD18bright) is strongly activated by the combination of IL-12 and IL-2. In this report we show that the functional synergy between IL-12 and IL-2 in CD8+CD18bright T cells correlates with the activation of the stress kinases, p38 mitogen-activated protein (MAP) kinase and stress-activated protein kinase (SAPK)/Jun N-terminal kinase, but not with the activation of the extracellular signal-regulated kinases. The functional synergy between IL-2 and IL-12 is also associated with a prominent increase in STAT1 and STAT3 serine phosphorylation over that observed with IL-12 or IL-2 alone. By contrast, STAT tyrosine phosphorylation is not augmented over that seen with either cytokine alone. A specific inhibitor of p38 MAP kinase completely inhibits the serine phosphorylation of STAT1 and STAT3 induced by IL-12 and IL-2 and abrogates the functional synergy between IL-12 and IL-2 without affecting STAT tyrosine phosphorylation. This suggests that p38 MAP kinase may play an important role in regulating STAT serine phosphorylation in response to the combination of IL-12 and IL-2. Furthermore, these findings indicate that the optimal activation of T cells by IL-12 and IL-2 may depend on an interaction between the p38 MAP kinase and Janus kinase/STAT signaling pathways.

A cis repression sequence adjacent to the transcription start site of the human cytomegalovirus US3 gene is required to down regulate gene expression at early and late times after infection

Human cytomegalovirus has two enhancer-containing immediate-early (IE) promoters with a cis repression sequence (CRS) positioned immediately upstream of the transcription start site, designated the major IE (MIE) promoter and the US3 promoter. The role of the CRS upstream of the US3 transcription start site in the context of the viral genome was determined by comparing the levels of transcription from these two enhancer-containing promoters in recombinant viruses with a wild-type or mutant CRS. Upstream of the CRS of the US3 promoter was either the endogenous enhancer (R2) or silencer (R1). The downstream US3 gene was replaced with the indicator gene chloramphenicol acetyltransferase (CAT). Infected permissive human fibroblast cells or nonpermissive, undifferentiated monocytic THP-1 cells were analyzed for expression from the US3 promoter containing either the wild-type or mutant CRS. With the wild-type CRS, the maximum level of transcription in permissive cells was detected within 4 to 6 h after infection and then declined. With the mutant CRS and the R2 enhancer upstream, expression from the US3 promoter continued to increase throughout the viral replication cycle to levels 20- to 40-fold higher than for the wild type. In nonpermissive or permissive monocytic THP-1 cells, expression from the US3 promoter was also significantly higher when the CRS was mutated. Less expression was obtained when only the R1 element was present, but expression was higher when the CRS was mutated. Thus, the CRS in the enhancer-containing US3 promoter appears to allow for a short burst of US3 gene expression followed by repression at early and late times after infection. Overexpression of US3 may be detrimental to viral replication, and its level of expression must be stringently controlled. The role of the CRS and the viral IE86 protein in controlling enhancer-containing promoters is discussed.

Embryonic stem cells and embryoid bodies express lymphocyte costimulatory molecules

Despite the importance of the costimulatory proteins B7-1 (CD80), B7-2 (CD86), and their counterreceptors CD28 and CTLA-4 (CD154) in the regulation of T cell proliferation in the adult immunological system, the initial appearance of these proteins during embryonic development has not been investigated. Using in vitro cultures of undifferentiated mouse embryonic stem (ES) cells and differentiating embryoid bodies as a model of very early embryonic development, we examined these cells for the presence of mRNA and protein corresponding to the B7 and CD28 families of costimulatory molecules. By flow cytometry, a stochastically regulated subpopulation of B7-1+ cells comprising 33% of total cells was detected in ES cell cultures, while negligible staining was found for B7-2, CTLA-4, and CD28. When ES cells were differentiated into embryoid bodies for 12 days, a CD45+ subpopulation of embryoid body cells were found to stain positively for B7-1, B7-2, and CD28. RT-PCR confirmed cell staining data by revealing amplification products corresponding to B7-1, B7-2, and CD28 in corresponding samples. Very low levels of CTLA-4 amplification products were found in all samples; however, surface staining of CTLA-4 was never detected. The functional capacity of ES cell B7-1 to bind its ligand was verified by the ability of the soluble fusion protein CTLA-4-Ig to bind ES cells and the ability of this reagent to block anti-B7-1 antibody binding in cell based competition assays. These results demonstrate that expression of costimulatory molecules arises very early during in vitro development and suggests that the early embryonic environment may utilize cellular signaling systems analogous to those seen in the immune system.

Altered interleukin-12 responsiveness in Th1 and Th2 cells is associated with the differential activation of STAT5 and STAT1

T-cell activation in response to interleukin-12 (IL-12) is mediated through signaling events that include the tyrosine phosphorylation of STAT4. IL-12 responsiveness and the ability of IL-12 to activate STAT4 is different in T cells induced to differentiate into a Th1 or Th2 phenotype. In this report, we show that STAT5, STAT1alpha, and STAT1beta, in addition to STAT4, are tyrosine phosphorylated in response to IL-12 in phytohemagglutinin (PHA)-activated human T cells. To understand how the activation of these STATs contributes to T-cell IL-12 responsiveness, we analyzed the IL-12-induced activation of STAT5 and STAT1 in T cells stimulated to undergo Th1 or Th2 differentiation. The IL-12-induced tyrosine phosphorylation of STAT5 and STAT1, but not STAT4, is augmented in T cells activated into Th1 cells with PHA + interferon-gamma (IFN-gamma) compared with T cells activated with PHA alone. STAT5 DNA binding induced by IL-12 is also augmented in T cells activated with PHA + IFN-gamma compared with T cells activated with PHA alone, whereas STAT4 DNA binding is not increased. In contrast, the IL-12-induced activation of these STATs is inhibited in T cells activated into Th2 cells with PHA + IL-4. The enhancement of IL-12 signaling by IFN-gamma is not a direct effect of IFN-gamma on T cells, but rather is mediated by IL-12 that is produced by antigen-presenting cells in response to IFN-gamma. This positive autoregulatory effect of IL-12 on the activation of select STATs correlates with an increase in T-cell IFN-gamma production in response to IL-12. These findings suggest that the activation of STAT5 and STAT1 may augment select STAT4-dependent functional responses to IL-12 in Th1 cells.

Direct and regulated interaction of integrin alphaEbeta7 with E-cadherin

The cadherins are a family of homophilic adhesion molecules that play a vital role in the formation of cellular junctions and in tissue morphogenesis. Members of the integrin family are also involved in cell to cell adhesion, but bind heterophilically to immunoglobulin superfamily molecules such as intracellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1, or mucosal addressin cell adhesion molecule (MadCAM)-1. Recently, an interaction between epithelial (E-) cadherin and the mucosal lymphocyte integrin, alphaEbeta7, has been proposed. Here, we demonstrate that a human E-cadherin-Fc fusion protein binds directly to soluble recombinant alphaEbeta7, and to alphaEbeta7 solubilized from intraepithelial T lymphocytes. Furthermore, intraepithelial lymphocytes or transfected JY' cells expressing the alphaEbeta7 integrin adhere strongly to purified E-cadherin-Fc coated on plastic, and the adhesion can be inhibited by antibodies to alphaEbeta7 or E-cadherin. The binding of alphaEbeta7 integrin to cadherins is selective since cell adhesion to P-cadherin-Fc through alphaEbeta7 requires >100-fold more fusion protein than to E-cadherin-Fc. Although the structure of the alphaE-chain is unique among integrins, the avidity of alphaEbeta7 for E-cadherin can be regulated by divalent cations or phorbol myristate acetate. Cross-linking of the T cell receptor complex on intraepithelial lymphocytes increases the avidity of alphaEbeta7 for E-cadherin, and may provide a mechanism for the adherence and activation of lymphocytes within the epithelium in the presence of specific foreign antigen. Thus, despite its dissimilarity to known integrin ligands, the specific molecular interaction demonstrated here indicates that E-cadherin is a direct counter receptor for the alphaEbeta7 integrin.

Nicotine-stimulated elastase activity release by neutrophils in patients with abdominal aortic aneurysms

Elevated elastase activity in patients with chronic obstructive pulmonary disease (COPD) is attributable to the direct effect of nicotine. COPD is also known to be an independent predictor of abdominal aortic aneurysm (AAA) growth and rupture. The purpose of this study is to determine the effect of nicotine on elastase activity release from neutrophils of AAA patients. Human neutrophils were extracted from the blood of subjects in the following six groups, n = 10 in each group: smoking AAA (SAAA), nonsmoking AAA (NSAAA), smoking aortic occlusive disease (SAOD), nonsmoking aortic occlusive disease (NSAOD), smoking controls (SC), and nonsmoking controls (NSC). After incubation with varying nicotine concentrations (0-1000 microg/ml), the released elastase activity was determined. There is generally an elevation in elastase activity release by neutrophils of smokers compared to nonsmokers. Nicotine exposure stimulated increased elastase activity release in AOD and AAA, and the increase was especially pronounced in the SAAA and SAOD groups. The elevation was greatest in the SAAA group while the release was lowest in the NSAOD group. There is a direct correlation between elastase activity release and nicotine concentration. The data suggest that COPD and AAA development, which may occur by similar initial mechanisms may also be aggravated by nicotine-induced neutrophil elastase activity release. In addition, the results indicate that nicotine is playing an active role in the development of vascular disease by inducing neutrophils to release elastase activity.

Laparoscopically assisted abdominal aortic aneurysm repair. A report of 10 cases

BACKGROUND

Laparoscopic surgery decreases postoperative pain and length of hospital stay. Whether laparoscopically assisted abdominal aortic aneurysm (AAA) repair can be safely and reliably performed is unknown. This prospective study was designed to establish the feasibility of laparoscopically assisted AAA repair and its effects on intraoperative and postoperative variables.

METHODS

With IRB approval, 10 patients with infrarenal AAA requiring a tube graft underwent laparoscopically assisted AAA repair. The procedure consisted of laparoscopic dissection of the aneurysm neck and iliac vessels. Then, through an 8-11-cm minilaparotomy, a standard endoaneurysmorrhaphy was performed. Data included laparoscopic and total operative times, blood loss, fluid requirements, duration of nasogastric suction (NGT), and lengths of intensive care unit (ICU) and postoperative hospital stays.

RESULTS

Laparoscopically assisted AAA was completed in nine of 10 patients. The first patient was converted to a standard incision because the aneurysm neck could not be adequately dissected. Laparoscopic and total operative times were 1.8 +/- 0.4 and 4.5 +/- 0.7 h, respectively. Mean blood loss was 1 +/- 0.6 l. Intraoperative fluid requirement was 6.6 +/- 1.3 l. The duration of NGT suction was 1.8 +/- 1.0 days. The ICU stay was 2.1 +/- 0.8 days and hospital stay was 6.7 +/- 2.5 days. There were two minor complications and no deaths.

CONCLUSIONS

Laparoscopically assisted AAA repair is technically feasible with acceptable blood loss, operative time, morbidity, and mortality. Potential advantages may be early removal of the NGT and shorter ICU and hospital stays. Prospective randomized trials are needed to determine if laparoscopically assisted AAA repair is advantageous.

Laparoscopic aortic replacement in the porcine model: a feasibility study in preparation for laparoscopically assisted abdominal aortic aneurysm repair in humans

BACKGROUND

Current laparoscopic vascular techniques have centered around aortofemoral bypass for the treatment of patients with aortic occlusive disease. However, the majority of aortic surgeries are performed for the treatment of aortic aneurysmal disease. With this mind, we undertook this study to assess the feasibility of laparoscopic aortic replacement in the porcine model in preparation for laparoscopically assisted abdominal aortic aneurysm (AAA) repair in humans.

STUDY DESIGN

Twenty-three female pigs weighing between 35 and 40 kg underwent laparoscopic aortic dissection by either a transabdominal or retroperitoneal approach. The infrarenal aorta was laparoscopically dissected, isolated, and cross clamped. Then a custom designed cuffed polytetrafluoroethylene graft was inserted. After reestablishing and confirming distal flow, the animals were sacrificed.

RESULTS

Fifteen functioning aortic grafts were placed in 21 animals who had the transabdominal approach. One functioning graft was placed in the retroperitoneal group. Complications included bladder, ureteral, inferior vena cava, renal vein, and aortic injuries. By the end of the study, the operative time was reduced from six to less than two hours; blood loss was reduced from 1,000 to 150 mL; and cross-clamping time was reduced from 60 to 15 minutes.

CONCLUSIONS

In the porcine model, laparoscopic abdominal aortic replacement is associated with a significant learning curve. However, this method of repair is technically feasible and warrants further investigation in the treatment of AAA in humans.

Low dose desensitisation does not reduce the toxicity of sulphasalazine in rheumatoid arthritis

OBJECTIVE

To examine the proposal that pretreatment low dose desensitisation may reduce the incidence of toxicity of sulphasalazine in the treatment of rheumatoid arthritis (RA).

METHODS

A double blind, placebo controlled trial was performed with 422 patients satisfying the American College of Rheumatology criteria for RA who required sulphasalazine treatment because of increased disease activity. Patients received either sulphasalazine desensitisation, or placebo, for three weeks before commencement of sulphasalazine treatment. The frequency and nature of adverse effects and changes in clinical and laboratory parameters of disease activity were measured after three and six months.

RESULTS

Improvement in the efficacy of sulphalasazine (measured by clinical and laboratory parameters) was significant and similar in magnitude in both groups. There was no significant difference between actively and placebo desensitised patients as regards the incidence or profile of adverse effects (toxicity).

CONCLUSION

Pretreatment low dose desensitisation is unhelpful in reducing the toxicity associated with sulphasalazine treatment of RA.

Patients' views of low back pain and its management in general practice

BACKGROUND

Low back pain is a common and persistent problem. Research studies seeking to improve the quality of management of this condition have tended to ignore the opinions of patients. There is a growing acceptance of the importance of taking patients' views into account in developing management and educational programmes for a variety of conditions.

AIM

This study set out to elicit the views of patients concerning low back pain and its management in general practice.

METHOD

Fifty-two in-depth interviews were conducted with patients selected from a broad range of 12 general practices.

RESULTS

Analysis of the interviews identified seven themes relating to: quality of life, prognosis, secondary prevention, help-seeking behaviour, explanation of underlying pathology, satisfaction with general practitioner management, and complementary therapy. Different patient viewpoints or perspectives were expressed within each of these themes. Patients adapted to the progress of their low back pain and were not seeking a 'magical cure' from either conventional or complementary therapies.

CONCLUSION

Patients' views on low back pain are heterogeneous. The dissatisfaction expressed with medical explanations for the pain may be related to superficial clinical management and the constraints of general practice. Good management of low back pain needs to take patients' complex views of the condition into account.

Inhibition by protease inhibitors of chemotaxis induced by elastin-derived peptides

We studied the effect of two inhibitors of human neutrophil proteases on neutrophil chemotaxis induced by the hexapeptide Val-Gly-Val-Ala-Pro-Gly (VGVAPG), a recurring sequence in the elastin molecule. The inhibitors were tosyl-Phe chloromethyl ketone (TFCK) and N-methoxysuccinyl-Ala-Ala-Pro-Val chloromethyl ketone (MAAPVCK). We assayed chemotactic activity by the double-membrane technique in a modified Boyden chamber, after incubating the cells for 1 hr with varying concentrations of inhibitor. We observed a concentration-dependent inhibitory effect. We also measured the potency of the two chloromethyl ketones as protease inhibitors. The more potent protease inhibitor, MAAPVCK, was also the more effective in inhibiting VGVAPG-induced chemotaxis; its inhibitor dissociation constant was KI = 28 nM with elastase and KI = 33 nM with cathepsin G. For TFCK the corresponding KI values were 37 microM and 200 microM. The incubating concentration required to lower chemotaxis by half its uninhibited value was C0.5 = 0.64 microM for MAAPVCK, compared to C0.5 = 3.4 microM for TFCK. A third peptide, triglycinate (gly3), which did not inhibit the proteolytic activity of either elastase or cathepsin G, did not inhibit chemotaxis. Chemotaxis induced by formyl Met-Leu-Phe (fMLP) was weakly inhibited by both chloromethyl ketones with TFCK being somewhat more effective than MAAPVCK. We concluded that inhibition of VGVAPG-induced chemotaxis is in part specific, receptor mediated. We suggest that proteolytic inhibitors protect the extracellular matrix from degradation by inhibiting chemotaxis. Comparing the inhibitor concentrations required to half proteolytic activity with the concentration required to half chemotactic activity, we further suggest that the two functions may be of comparable significance.