Determinants of Slow Walking Speed in Ambulatory Patients Undergoing Maintenance Hemodialysis

Walking ability is significantly lower in hemodialysis patients compared to healthy people. Decreased walking ability characterized by slow walking speed is associated with adverse clinical events, but determinants of decreased walking speed in hemodialysis patients are unknown. The purpose of this study was to identify factors associated with slow walking speed in ambulatory hemodialysis patients. Subjects were 122 outpatients (64 men, 58 women; mean age, 68 years) undergoing hemodialysis. Clinical characteristics including comorbidities, motor function (strength, flexibility, and balance), and maximum walking speed (MWS) were measured and compared across sex-specific tertiles of MWS. Univariate and multivariate logistic regression analyses were performed to examine whether clinical characteristics and motor function could discriminate between the lowest, middle, and highest tertiles of MWS. Significant and common factors that discriminated the lowest and highest tertiles of MWS from other categories were presence of cardiac disease (lowest: odds ratio [OR] = 3.33, 95% confidence interval [CI] = 1.26–8.83, P<0.05; highest: OR = 2.84, 95% CI = 1.18–6.84, P<0.05), leg strength (OR = 0.62, 95% CI = 0.40–0.95, P<0.05; OR = 0.57, 95% CI = 0.39–0.82, P<0.01), and standing balance (OR = 0.76, 95% CI = 0.63–0.92, P<0.01; OR = 0.81, 95% CI = 0.68–0.97, P<0.05). History of fracture (OR = 3.35, 95% CI = 1.08–10.38; P<0.05) was a significant factor only in the lowest tertile. Cardiac disease, history of fracture, decreased leg strength, and poor standing balance were independently associated with slow walking speed in ambulatory hemodialysis patients. These findings provide useful data for planning effective therapeutic regimens to prevent decreases in walking ability in ambulatory hemodialysis patients.     

Characterization of Vibrio cholerae O1 isolates responsible for cholera outbreaks in Kenya between 1975 and 2017

Kenya is endemic for cholera with different waves of outbreaks having been documented since 1971. In recent years, new variants of Vibrio cholerae O1 have emerged and have replaced most of the traditional El Tor biotype globally. These strains also appear to have increased virulence, and it is important to describe and document their phenotypic and genotypic traits. This study characterized 146 V. cholerae O1 isolates from cholera outbreaks that occurred in Kenya between 1975 and 2017. Our study reports that the 1975–1984 strains had typical classical or El Tor biotype characters. New variants of V. cholerae O1 having traits of both classical and El Tor biotypes were observed from 2007 with all strains isolated between 2015 and 2017 being sensitive to polymyxin B and carrying both classical and El Tor type ctxB. All strains were resistant to Phage IV and harbored rstR, rtxC, hlyA, rtxA and tcpA genes specific for El Tor biotype indicating that the strains had an El Tor backbone. Pulsed field gel electrophoresis (PFGE) genotyping differentiated the isolates into 14 pulsotypes. The clustering also corresponded with the year of isolation signifying that the cholera outbreaks occurred as separate waves of different genetic fingerprints exhibiting different genotypic and phenotypic characteristics. The emergence and prevalence of V. cholerae O1 strains carrying El Tor type and classical type ctxB in Kenya are reported. These strains have replaced the typical El Tor biotype in Kenya and are potentially more virulent and easily transmitted within the population.     

Reflections on the Conservation and Sustainable Use of Genetic Resources in the Deep Seabed Beyond the Limits of National Jurisdiction

Attention is increasingly being given to genetic resources in the deep seabed beyond the limits of national jurisdiction owing to their considerable potential scientific and economic value. At the same time, there are concerns that the increased demand for these genetic resources may result in their unsustainable collection or even in the extinction of species in the deep seabed. At present there is no specific legal framework governing these resources in international law. Thus, this article explores the relevant rules of international law applicable to the conservation and sustainable use of genetic resources in the deep seabed.     

Winged leaf-cutting ants on nuptial flights used as transport by Attacobius spiders for dispersal

Abstract.  1. Sexuals of a leaf-cutting ant, Atta bisphaerica Forel, left their nest for nuptial flights in October to December.
2. When leaving a nest, 53 of the 479 winged sexuals (or alates) observed (11.1%) carried up to three inquiline spiders of Attacobius luederwaldti .
3. Spiders exclusively selected winged sexuals, not workers, and preferred females, indicating their expectation of the stronger flight ability of females. Neither these sexuals nor workers that appeared out of the nest on flight days attempted to remove or attack spiders on the body of alates.
4. New qucens landing from their nuptial flight did not carry spiders, indicating that the spiders had left the ants in the sky to be dispersed by wind.
5. No spiders were found in more than 100 incipient nests, which were estimated to be 2–3 months old. This suggests that the spiders jumped off the alate during mid-flight and dispersed on the wind to inhabit larger nests.     

Cloning of a Vero toxin (VT2) gene from a VT2-converting phage isolated from Escherichia coli 0157: H7

Abstract A Vero toxin (VT2 or Shiga-like toxin II)-converting phage was isolated from Escherichia coli 0157: H7 strain J-2. Nontoxigenic E. coli C600 produced VT2 when lysogenized with the toxin-converting phage. Eco RI fragments of the phage DNA were ligated with Eco RI-digested pBR322 or pUC118 and were transformed into E. coli MC1061 or MV1184. Transformants exhibiting VT2 production commonly contained a 4.6 kb Eco RI fragment. It was found that a 2.3 kb Kpn I- Sph I fragment coded VT2 production and that this fragment hybridized weakly with the 2.1 kb fragment encoding VT1.     

Protective role of potentially lethal damage repair in the neoplastic transformation of Balb/c 3T3 cells treated with N-methyl-N'-nitro-N-nitrosoguanidine

To determine the role of repair of potentially lethal damage (PLD) in the initiation process of neoplastic transformation, Balb/c 3T3 cells treated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were temporarily exposed to conditioned medium obtained from density-inhibited Chinese hamster cell cultures, as a post-treatment for the induction of PLD repair. With or without this exposure, cell survival and transformation frequencies were simultaneously determined by colony-formation and focus-formation assays, respectively. Temporary exposure to conditioned medium resulted in a 20-30% increase in cell survival compared with no exposure. Post-treatment with conditioned medium resulted in a 60-65% reduction in transformation frequencies. At the molecular level, the repair of MNNG-induced single-strand breaks of DNA occurred much more rapidly in conditioned medium. These data suggest that PLD repair reduces the in vitro neoplastic transformation through excision repair operative during the cessation of DNA replication. Thus, PLD repair appears to be preventive against neoplastic fixation in initiation of neoplastic development.     

Determination of free sulphite in wine using a microbial sensor

Summary A microbial sensor of immobilized Thiobacillus thiooxidans S3 cells was assembled to determine free sulphite in wine. Sulphite oxidation activity of the immobilized cells was sufficiently high for use even after 3 months storage at 4° C. The sensitivity of this sensor was 116 nA·1·mg^-1 for sulphur dioxide. The relationship between the current decrease and the sulphur dioxide concentration was linear up to 17 mg·1^-1. The sampling rate achieved was 10 min per sample including washing time. This sensor method needed no pretreatment of wine samples, and wines diluted with 5 mM sulphuric acid solution could be directly introduced in the computer-aided analysis system. The pigments in red wine did not disturbed the analysis.     

Destruction of tumor cells by monokines released from activated human blood monocytes: evidence for parallel and additive effects of IL-1 and TNF

Summary The incubation of human peripheral blood monocytes with endotoxins activates the cells to lyse tumorigenic targets directly and also induces the production and release into the culture medium of factors that produce lysis of mouse-transformed fibroblasts L-929 (tumor necrosis factor (TNF)-sensitive) and human A-375 melanoma cells (interleukin-1 (IL-1)- and TNF-sensitive). Immunoblotting analysis revealed that the culture medium of endotoxin-activated but not of control monocytes contained both IL-1 and TNF with a molecular weight of 17,000 daltons each. TNF activity was determined by lysis of L-929 cells, and IL-1 activity was measured by the proliferation of D-10 cells. The production of IL-1 and TNF was concentration-dependent, and the amounts of these monokines were paralleled. The antitumor activity of the culture supernates from endotoxin-treated monocytes was significantly decreased by incubation with heterologous antisera to IL-1, TNF, or both. Recombinant human IL-1 and TNF were used in parallel experiments and as positive controls. Each monokine used produced cytotoxic effects in susceptible targets. The combination of IL-1 and TNF, which more likely resembles culture supernates of activated macrophages, produced an additive antitumor cytotoxicity effect.     

Tumor necrosis factor and IL-1 associated with plasma membranes of activated human monocytes lyse monokine-sensitive but not monokine-resistant tumor cells whereas viable activated monocytes lyse both

The purpose of our study was to determine some of the mechanisms involved in macrophage-mediated lysis of tumorigenic cells. A375 human melanoma cells (A375-R) resistant to lysis mediated by TNF and IL-1 were selected from the TNF- and IL-1-sensitive A375 parental melanoma cells subsequent to continuous (2 mo) exposure to rTNF. Peripheral blood monocytes isolated by centrifugal elutriation from healthy donors were incubated with rIFN-gamma and muramyl dipeptide, with a lipoprotein derived from Escherichia coli (CG-31362) or with LPS for 24 h. These activated monocytes lysed both the A375 (monokine-sensitive) and A375-R (monokine-resistant) melanoma cells. Activated tumoricidal macrophages fixed in 2% paraformaldehyde lysed only the TNF- and IL-1-sensitive A375 cells. These fixed monocytes contained both IL-1 and TNF activities as determined by D10 cell proliferation and L929 cytolysis assays, respectively. Nearly identical results were obtained with preparations of plasma membranes from activated human monocytes. Anti-IL-1 and/or anti-TNF sera neutralized the cytolysis of tumor cells mediated by free monokines, by fixed monocytes, or by plasma membrane preparations. In contrast, anti-TNF and/or anti-IL-1 sera did not inhibit tumor cell lysis by viable activated monocytes. We conclude that IL-1 and TNF molecules associated with the plasma membranes of activated monocytes mediate lysis of susceptible target cells. However, because activated monocytes lysed IL-1-and TNF-resistant target cells, molecules other than these monokines must also be involved in the antitumor activity of monocytes.