Robotic ventral mesh rectopexy for rectal prolapse: a single-institution experience.

BACKGROUND: Robotic ventral mesh rectopexy (RVMR) is an appealing approach for the treatment of rectal prolapse and other conditions. The aim of this study was to evaluate the outcomes of RVMR for rectal prolapse. METHODS: We performed a retrospective chart review for patients who underwent RVMR for rectal prolapse at our institution between July 2012 and May 2016. Any patient who underwent RVMR during this time frame was included in our analysis. Any cases involving colorectal resection or other rectopexy techniques were excluded. RESULTS: Of the 24 patients who underwent RVMR, 95.8% of patients were female. Median age was 67.5 years old (IQR 51.5-73.3), and 79.2% of patients were American Society of Anesthesiologists class III or IV. Median operative time was 191 min (IQR 164.3-242.5), and median length of stay was 3 days (IQR 2-3). There were no conversions, RVMR-related complications or mortality. Patients were followed for a median of 3.8 (IQR 1.2-15.9) months. Full-thickness recurrence occurred in 3 (12.4%) patients. Rates of fecal incontinence improved after surgery (62.5 vs. 41.5%, respectively) as did constipation (45.8 vs. 33.3%, respectively). No patients reported worsening symptoms postoperatively. Only one (4.2%) patient reported de novo constipation postoperatively. CONCLUSIONS: RVMR is a feasible, safe and effective option for the treatment of rectal prolapse, with low short-term morbidity and mortality. Multicenter and long-term studies are needed to better assess the benefits of this procedure.

Frequency of TLR4 (1063A/G and 1363C/T) polymorphisms in healthy and HIV-infected Omani individuals and their relationship to viral load and T cell count.

Toll-like receptors (TLRs) are essential elements of the innate immune response to different infections including the infection with human immunodeficiency virus (HIV). Single nucleotide polymorphisms (SNPs) in TLRs such as TLR4 1063A/G and 1363C/T have been found to be associated with changes in CD4 count, viral load (VL), and disease progression during HIV infection. However, the association of these SNPs with the pathogenesis during HIV infection is controversial. We investigated the frequency of TLR4 1063A/G and 1363C/T SNPs in 168 Omani donors [68 HIV-infected patients (>3% of Omani HIV-infected patients) and 100 healthy controls] and the association of these SNPs with the VL, CD8 and CD4 counts, and the immune recovery after cART as observed by CD4 T cell increase. SNPs were analyzed after the amplification of the regions that contain them by polymerase chain reaction (PCR) and sequencing of the PCR products. The TLR4 1063GG genotype was detected in the HIV-infected group only. No association was found between the studied SNPs and the average VL during 1 year of infection, the average CD4 and CD8 count during 1 year of viremia, the nadir CD4 count, the CD4 count when the patient reached VL < 50 copies/mL due to cART, and the ratio of the CD4 count 3 and 6 months after reaching VL < 50 copies/mL after cART to the last CD4 count before reaching VL < 50 copies/mL. Our study suggests that TLR4 (1063A/G and 1363C/T) SNPs have no association with the VL or the CD4 and CD8 counts during HIV infection.

Knowledge, attitudes and intended behaviours towards HIV testing and self-protection: a survey of Omani pregnant women.

Routine HIV testing of all pregnant women in Oman has been introduced without prior knowledge of women's attitudes towards testing or their behaviour in the event of a positive test. This study recruited 1000 Omani pregnant women from antenatal clinics to explore their knowledge of HIV/AIDS, attitudes towards HIV testing and intended behaviours in the event of a positive test. Mother-to-child transmission was recognized by 86.6% of the women but only 21.0% knew that it was preventable and a few acknowledged the important role of antiviral drugs. Half of the women (51.9%) reported having been tested for HIV and 75.8% agreed about routine HIV testing for all pregnant women. A higher level of knowledge was significantly associated with a favourable intended behaviour related to voluntary testing, disclosure and seeking professional assistance in the event of a positive HIV test. The results are discussed in relation to opt-in and opt-out approaches to voluntary testing during pregnancy.

Association of single-nucleotide polymorphisms in TLR7 (Gln11Leu) and TLR9 (1635A/G) with a higher CD4T cell count during HIV infection.

BACKGROUND: Toll-like receptors (TLRs) are essential elements of the innate immune response to different infections including HIV-1 infection. The single-nucleotide polymorphisms (SNPs) in TLRs have been associated with CD4T cell count and HIV disease progression. The TLR7 (Gln11Leu) SNP was shown to be associated with a rapid decline of CD4T cell count. A relation between TLR9 (1635A/G) SNP and CD4T cells count in HIV-infected patients is suggested, although the outcome associated with this SNP is still controversial. OBJECTIVES: To determine the relation of the TLR7 (Gln11Leu) and TLR9 (1635A/G) SNPs with the damage to the immune system during HIV infection as reflected by the average CD4T cell count. METHODS: A total of 63 HIV-infected patients and 100 healthy individuals (controls) were enrolled in this study. The above named SNPs were analyzed after amplification of the regions that potentially contain the SNPs by polymerase chain reaction (PCR) and sequencing of the PCR products. The frequency of these SNPs and their relation with the CD4T cell count were investigated. RESULTS: The TLR7 (AA) genotype 'Gln' had a trend toward being associated with a CD4T cell count >400cells/µl after controlling viremia via HAART. Additionally, the TLR9 1635 (GG) genotype was associated with a low average CD4T cell count and the TLR9 1635 (AG) genotype was significantly related to a higher average CD4T cell count during the viremic period in HIV-infected patients. CONCLUSION: The results of this longitudinal study supports the presence of an association between the TLR9 (1635A/G) genotype and the CD4T cell count, which helps clarifying the controversial results regarding this association. It also suggests that the CD4T cell count during the viremic period might be linked to the combination of both TLR7 (Gln11Leu) and TLR9 (1635A/G) genotypes. These results may help predicting the damage to the immune system, and thus impacting the planning for novel anti-HIV strategies.

New genetic variants in the CCR5 gene and the distribution of known polymorphisms in Omani population.

C-C motif chemokine receptor-5 (CCR5) is a pro-inflammatory receptor that binds to chemokines and facilitates the entry of the R5 strain of HIV-1. A number of polymorphisms were identified within the promoter and coding regions of the CCR5 gene, some of which have been found to affect the protein expression and thus receptor function. Although several CCR5 polymorphisms were shown to vary widely in their distribution among different ethnic populations, there has been no study addressing the potential variants of the CCR5 gene in the Omani population. The aim of this study was to identify the polymorphic sites that exist within the CCR5 gene in Omanis. Blood samples were collected from 89 Omani adult individuals, and genomic DNA was amplified by polymerase chain reaction and sequenced to identify the polymorphic sites. The distribution of the detected variants was examined and compared with the previously published data. Four new indels were detected of 32 variable positions, -2973A/-, -2894A/-, -2827TA/- and -2769T/-, and all were located in the 5'UTR. Furthermore, two new mutations, -2248G/A and +658A/G, were observed for the first time; the -2248G/A was detected in the intron 1 region in one subject and +658A/G in the coding region of the CCR5 in another subject. In silico analysis showed that the novel variations in the 5'UTR may have effects on the transcription factor binding sites. Therefore, this study demonstrates the presence of two new SNPs and four novel indels in the CCR5 gene in the Omani population. Our findings support the wide spectrum of genetic diversity reported within the CCR5 gene region among different ethnic groups.

Bioenergy co-products derived from microalgae biomass via thermochemical conversion--life cycle energy balances and CO2 emissions.

An investigation of the potential to efficiently convert lipid-depleted residual microalgae biomass using thermochemical (gasification at 850 °C, pyrolysis at 550 °C, and torrefaction at 300 °C) processes to produce bioenergy derivatives was made. Energy indicators are established to account for the amount of energy inputs that have to be supplied to the system in order to gain 1 MJ of bio-energy output. The paper seeks to address the difference between net energy input-output balances based on a life cycle approach, from "cradle-to-bioenergy co-products", vs. thermochemical processes alone. The experimental results showed the lowest results of Net Energy Balances (NEB) to be 0.57 MJ/MJ bio-oil via pyrolysis, and highest, 6.48 MJ/MJ for gas derived via torrefaction. With the complete life cycle process chain factored in, the energy balances of NEBLCA increased to 1.67 MJ/MJ (bio-oil) and 7.01 MJ/MJ (gas). Energy efficiencies and the life cycle CO2 emissions were also calculated.

One-dimensional hypersonic phononic crystals.

We report experimental observation of a normal incidence phononic band gap in one-dimensional periodic (SiO(2)/poly(methyl methacrylate)) multilayer film at gigahertz frequencies using Brillouin spectroscopy. The band gap to midgap ratio of 0.30 occurs for elastic wave propagation along the periodicity direction, whereas for inplane propagation the system displays an effective medium behavior. The phononic properties are well captured by numerical simulations. The porosity in the silica layers presents a structural scaffold for the introduction of secondary active media for potential coupling between phonons and other excitations, such as photons and electrons.

Immunobiology of natural killer cells and bone marrow transplantation: merging of basic and preclinical studies.

Natural killer (NK) cells mediate acute rejection of bone marrow, but not solid tissue, allografts in lethally irradiated mice. Precisely how and why this rejection occurs is still unclear. In allogeneic bone marrow transplantation (BMT), a spectrum of results is possible; one result can be marrow graft failure due to host rejection of the graft by NK and T cells and, at the opposite spectrum, the occurrence of graft-versus-host disease (GVHD). Donor NK cells, however, appear capable of improving donor engraftment without giving rise to GVHD and thus may be of use as an immunotherapy following BMT. As NK-cell inhibitory receptors play a role in bone marrow cell rejection, these same inhibitory receptors may also affect NK responses towards tumor cells. It has been demonstrated that blocking the interaction of inhibitory receptors with MHC determinants on tumor cells can result in greater antitumor effects. Thus, NK cells are capable of mediating both positive and negative effects during BMT depending on whether they are of host versus donor origin and their state of activation. Understanding their role in BMT provides insights as to their physiological roles and points the way to potential clinical uses.

Augmentation of antitumor effects by NK cell inhibitory receptor blockade in vitro and in vivo.

Subsets of natural killer (NK) cells are characterized by the expression of inhibitory and/or stimulatory receptors specific for major histocompatibility complex (MHC) class I determinants. In mice, these include the Ly49 family of molecules. One mechanism by which tumor cells may evade NK cell killing is by expressing the appropriate MHC class I and binding inhibitory Ly49 receptors. Therefore, the question of whether blocking the interaction between the Ly49 inhibitory receptors on NK and MHC class I cells on tumor cells augments antitumor activity was investigated. Blockade of Ly49C and I inhibitory receptors using F(ab')(2) fragments of the 5E6 monoclonal antibody (mAb) resulted in increased cytotoxicity against syngeneic tumors and decreased tumor cell growth in vitro. The effect of 5E6 F(ab')(2) was specific for the MHC of the tumor, as the use of F(ab')(2) of the mAb against Ly49G2 failed to increase NK activity. Treatment of leukemia-bearing mice with 5E6 F(ab')(2) fragments or adoptive transfer of NK cells treated ex vivo with the F(ab')(2) resulted in significant increases in survival. These results demonstrate that blockade of NK inhibitory receptors enhances antitumor activity both in vitro and in vivo, suggesting that NK inhibitory receptors can be responsible for diminishing antitumor responses. Therefore, strategies to block inhibitory receptors may be of potential use in increasing the efficacy of immunotherapy. (Blood. 2001;97:3132-3137)

The functional relevance of NK-cell-mediated upregulation of antigen-specific IgG2a responses.

We have previously shown that activation of NK cells by poly(I:C) or tumor treatment of mice increases the level of antigen-specific IgG2a (1, 2). We have now assessed the functional relevance of this effect of the innate immune system on the specific immune response. We found that the increased IgG2a significantly augments antibody-dependent cellular cytotoxicity mediated by NK cells both in vivo and in vitro. Furthermore, we show that both IgG3 producing plasma cells induced by T-independent antigens and IgG2a plasma cells induced in the presence of activated NK cells may be just as long-lived as plasma cells induced by T-dependent antigens. These results indicate that if NK cells are activated early in the immune response, before T cells are recruited, they could exert long-lasting effects.

Adoptive cellular immunotherapy: NK cells and bone marrow transplantation.

Allogeneic bone marrow transplantation (BMT) has been increasingly used for the treatment of both neoplastic and non-neoplastic disorders. However, serious obstacles currently limit the efficacy and thus more extensive use of BMT. These obstacles include: graft-versus-host disease (GVHD), relapse from the original tumor, and susceptibility of patients to opportunistic infections due to the immunosuppressive effects of the conditioning regimen. Overcoming these obstacles is complicated by dual outcome of existing regimens; attempts to reduce GVHD by depleting T cells from the graft, result in increased rates of tumor relapse and failure of engraftment. On the other hand, efforts to increase graft-versus-tumor (GVT) effects of the transplant also promote GVHD. In this review, the use of natural killer (NK) cells to overcome some of these obstacles of allogeneic BMT is evaluated. Adoptive immunotherapy using NK cells after allogeneic BMT has several potential advantages. First, NK cells can promote hematopoiesis and therefore engraftment by production of hematopoietic growth factors. Second, NK cells have been shown to prevent the incidence and severity of GVHD. This has been shown to be at least partially due to TGF-beta, an immunosuppressive cytokine. Third, NK cells have been shown to augment numerous anti-tumor effects in animals after BMT suggesting a vital role of NK cells in mediating GVT effects. Finally, NK cells have been demonstrated to affect B cell recovery and function in mice. Therefore, understanding the mechanisms of beneficial effects of NK cells after BMT may lead to significant increases in the efficacy of this procedure.

Defensins act as potent adjuvants that promote cellular and humoral immune responses in mice to a lymphoma idiotype and carrier antigens.

Defensins released by neutrophils are able to kill a broad spectrum of microbes. They also induce leukocyte migration in vitro and elicit inflammatory leukocyte responses at s.c. injection sites in mice. In vitro experiments showed that human defensins enhanced concanavalin A-stimulated murine spleen cell proliferation and IFN-gamma production. This led us to examine the effects of human defensins on specific immune responses in vivo. BALB/c mice were immunized with 50 microg of keyhole limpet hemocyanin (KLH) adsorbed to aluminum hydroxide and administered with defensins in aqueous solution. Intraperitoneal administration of defensins significantly increased the production of KLH-specific IgG1, IgG2a and IgG2b antibodies 14 days after immunization. In vitro splenic KLH-specific proliferative responses were higher in mice treated with KLH and defensins than in those treated with KLH alone. Increased IFN-gamma and, to a lesser extent, IL-4 production were also detected in the supernatants of ex vivoKLH-activated spleen cells from mice treated with defensins. Finally, defensins significantly enhanced the antibody response to a syngeneic tumor antigen, lymphoma Ig idiotype and also augmented resistance to tumor challenge. These results indicate that defensins act as potent immune adjuvants by inducing the production of lymphokines, which promote T cell-dependent cellular immunity and antigen-specific Ig production. Thus, defensins appear to function as neutrophil-derived signals that promote adaptive immune responses.

The mechanism of activation of NK-cell IFN-gamma production by ligation of CD28.

We have investigated the mechanism by which anti-CD28 antibodies activates IFN-gamma production by murine NK cells. These studies reveal that engagement of CD28 alone by this antibody is a poor activator of this cytokine response. Effective stimulation requires simultaneous ligation of the receptor for Fc (FcgammaRIII, CD16) which on its own is also a poor inducer of murine NK cells. The mechanism by which immobilized anti-CD28 increases IFN-gamma mRNA abundance involves both upregulation of transcription as well as induction of mRNA stabilization. However, the elevation of transcription is not as evident as that induced by IL-12 which, in contrast, does not induce message stabilization. Thus ligation of CD28 in the presence of IL-12 results in a synergistic increase in production of the cytokine. Using this assay we have also determined that immobilized anti-CD28 cannot induce resting NK cells to produce IFN-gamma. In contrast, the same cells can be induced by BCL1-C11 tumor cells that express high amounts of the CD28 ligand, B7-2. These studies provide important insights into the ability of cells bearing counter-receptor for CD28 to activate NK cell-cytokine production in vivo.

The effect of NK cell activation by tumor cells on antigen-specific antibody responses.

In addition to mediating direct cytotoxicity, NK cells can exert regulatory effects on specific immune responses. For example, injection of poly (I:C) can alter specific Ab responses, which is attributable to the production of IFN-gamma by NK cells. To test whether direct activation of NK cells can exert the same effect, we have injected, at the same time as Ag challenge, BCL1-C11 tumor cells, which are highly effective inducers of IFN-gamma production by NK cells. The results show a specific enhancement of the IgG2a response, which does not occur with a tumor (70Z/3) that does not induce IFN-gamma production. This enhancement is NK cell and IL-12 dependent. However, BCL1-C11 cells cannot directly induce IL-12 production in peritoneal exudate cells (PECs). On the other hand, PECs from tumor-treated mice produce IL-12 in response to LPS, suggesting that they are primed in vivo. Furthermore, the IL-12 production is NK cell and IFN-gamma dependent. These results indicate that if tumor cells can directly activate NK cells to produce IFN-gamma, this cytokine initiates an amplification loop by activating macrophages to produce IL-12, which in turn activates NK cells further, resulting in the alteration of the isotype distribution of specific Ab responses. Production of the appropriate Ab isotype should enhance Ab-dependent cellular cytotoxicity against targets mediated by NK cells, implicating their role(s) in the specific immune response as well as the initial nonspecific phase.

The role of NK cells during in vivo antigen-specific antibody responses.

Investigations into the role of NK cells in regulating Ab responses have yielded variable results, some suggesting that NK cells can down-regulate Ag-specific Ig production and others proposing an enhancing effect. These apparently inconsistent findings may stem partially from the specificity of reagents used in purifying cell populations and/or the nature of the in vitro systems used to study these events. We chose to investigate the ability of either resting or poly(I:C)-activated NK cells to alter an in vivo Ab response in mice given a T-independent (TNP-LPS) or T-dependent (TNP-keyhole limpet hemocyanin (KLH)) Ag. By using a more specific Ab, anti-NK-1.1, to deplete NK cells, we were able to clearly show that resting, endogenous NK cells do not affect either type of response, as measured by serum Ag-specific Ig levels quantitated by isotype-specific ELISA. In contrast, activation of NK cells by poly(I:C) increased Ag-specific IgC2a as well as IgG1 levels. Interestingly, only the effect on IgG2a production is reversible by depletion of NK cells.

Interactions between B lymphocytes and NK cells.

The ability of natural killer (NK) cells to secrete lymphokines confers upon them the potential to regulate cell types via mechanisms other than direct cytotoxicity. During the past few years increasing evidence has been accumulating to show that NK and B cells can interact productively. First, NK cells cocultured with B cells can induce them to initiate polyclonal Ig secretion. This help is mediated by a soluble factor (or factors) that appears to be different from any known cytokine. Second, preactivated B lymphocytes can induce NK cells to produce greater amounts of IFN-gamma via an interaction that requires direct cell contact. Third, in contrast to previous suggestions, NK cells do not have the ability to kill primary B lymphocytes regardless of their stage of differentiation. Evaluation of the in vivo relevance of these interactions revealed that activated NK cells can increase the IgG2a response to a specific protein antigen. Without activation, NK cells neither enhance nor inhibit B cell responses to antigens. The deviation of the isotype distribution may allow increased NK cell specificity for certain pathogens by enhancing antibody-dependent cytotoxicity.

Prolactin receptor expression by lymphoid tissues in normal and immunized rats.

Prolactin receptor (PRLr) expression and distribution in thymus, spleen, bone marrow, lymph nodes, and peripheral blood lymphocytes from young adult Lewis rats are analyzed using single-color flow cytometry and a well-characterized monoclonal antibody directed against the rat liver PRLr. The in vivo effects of regional immunization on PRLr expression are also examined. PRLr is found to be widely distributed among cells of the immune system and demonstrates lymphoid tissue-specific patterns of expression. Footpad immunization caused the rapid, but transient, induction of PRLr expression in the draining lymph node, with only modest effects on PRLr expression in other distant lymphoid tissues. These studies indicate that PRL may be capable of direct interaction with the immune system through differential expression of the PRL cell surface receptor on select lymphoid target cell populations.