Fluorescent-Antibody Study of Natural Finger-Like Zooloeae

Fluorescent-antibody techniques using Zoogloea ramigera 106 antiserum were used to study fresh activated sludge flocs and finger-like zoogloeae in the microbial film that developed over stored samples of activated sludge. Few cells in fresh activated sludge reacted positively with the fluorescein-labeled antiserum. Finger-like zoogloeae containing reactive cells were readily observed in the microbial film layer over stored activated sludge. Certain of the natural finger-like projections were entirely composed of cells that reacted positively to the labeled Z. ramigera 106 antiserum, whereas other projections were devoid of reactive cells.     

Proteolytic activity within lysosomes and turnover of pinocytic vesicles a kinetic analysis

In previous studies, in vitro digestion of [^{1 2 5}I] ribonuclease by lysosomes of mouse kidney was limited because breakdown, which was rapid at first slowed markedly so that most of the labeled protein escaped degradation. We now describe incubation conditions which allow digestion to proceed until approximately 70% of the exogenous protein label is released in acid-soluble from, after 30–45 min at 37°C. Such activity is seen with either the addition of EDTA or incubation of concentrated cell particle suspensions. EDTA is effective in low concentrations and shows the same stimulation of digestion over a range of approximately 10⁻⁶−10⁻³ M. Other chelating agents have similar effects; dipyridyl and hydroxquinoline are as effective as EDTA, o-phenanthroline and diethyldithiocarbamate are slightly less effective. When the incubation medium had been treated with a chelating resin, Chelex 100, dilute suspensions of lysosomes were as active as those in EDTA. These results lead to the conclusion that metal ions, present as contaminants in very small concentraions, inhibit the activity of mouse kidney lysosomes.The effect of the metal ions is to diminish lysosomal stability, leading to release of intact labeled ribonuclease in non-sedimentable form. Interaction between lysosomes and metal, leading to inhibition of digestion upon heating occurs at low temperature, but breakdown requires incubation at 37°C and may be autolytic. In contrast to chelators, mercaptoethanol is without marked effect on stability; the stimulation in digestion rate caused by this agent is due either to a direct effect on the lysosomal enzymes or to a non-destructive influence on the lysosomal structure.     

Selective toxicity of wyerone and other phytoalexins to gram-positive bacteria

The antibacterial activities of isoflavonoid (kievitone and phaseollin), flavonoid (hydroxyflavans), furanoacetylenic (wyerone), and sesquiterpenoid (capsidiol and rishitin), phytoalexins against eight Gram-negative and six Gram-positive bacteria were examined using the paper-disc antibiotic assay method. With the exception of capsidiol, which was inactive at the highest concentration tested (200,μg/disc) all of the phytoalexins were selectively toxic towards Gram-positive species. Wyerone and kievitone were generally more toxic than other phytoalexins; rishitin was the least active inhibitor.     

Predictors of Condom Use among Peer Social Networks of Men Who Have Sex with Men in Ghana,West Africa

Ghanaian men who have sex with men (MSM) have high rates of HIV infection. A first step in designing culturally relevant prevention interventions for MSM in Ghana is to understand the influence that peer social networks have on their attitudes and behaviors. We aimed to examine whether, in a sample of Ghanaian MSM, mean scores on psychosocial variables theorized to influence HIV/STI risk differed between peer social networks and to examine whether these variables were associated with condom use. We conducted a formative, cross-sectional survey with 22 peer social networks of MSM (n = 137) in Ghana. We assessed basic psychological-needs satisfaction, HIV/STI knowledge, sense of community, HIV and gender non-conformity stigmas, gender equitable norms, sexual behavior and condom use. Data were analyzed using analysis of variance, generalized estimating equations, and Wilcoxon two sample tests. All models were adjusted for age and income, ethnicity, education, housing and community of residence. Mean scores for all psychosocial variables differed significantly by social network. Men who reported experiencing more autonomy support by their healthcare providers had higher odds of condom use for anal (AOR = 3.29, p<0.01), oral (AOR = 5.06, p<0.01) and vaginal (AOR = 1.8, p<0.05) sex. Those with a stronger sense of community also had higher odds of condom use for anal sex (AOR = 1.26, p<0.001). Compared to networks with low prevalence of consistent condom users, networks with higher prevalence of consistent condom users had higher STD and HIV knowledge, had norms that were more supportive of gender equity, and experienced more autonomy support in their healthcare encounters. Healthcare providers and peer social networks can have an important influence on safer-sex behaviors in Ghanaian MSM. More research with Ghanaian MSM is needed that considers knowledge, attitudes, and norms of their social networks in the development and implementation of culturally relevant HIV/STI prevention intervention strategies.     

Medial Temporal Lobe Roles in Human Path Integration

Path integration is a process in which observers derive their location by integrating self-motion signals along their locomotion trajectory. Although the medial temporal lobe (MTL) is thought to take part in path integration, the scope of its role for path integration remains unclear. To address this issue, we administered a variety of tasks involving path integration and other related processes to a group of neurosurgical patients whose MTL was unilaterally resected as therapy for epilepsy. These patients were unimpaired relative to neurologically intact controls in many tasks that required integration of various kinds of sensory self-motion information. However, the same patients (especially those who had lesions in the right hemisphere) walked farther than the controls when attempting to walk without vision to a previewed target. Importantly, this task was unique in our test battery in that it allowed participants to form a mental representation of the target location and anticipate their upcoming walking trajectory before they began moving. Thus, these results put forth a new idea that the role of MTL structures for human path integration may stem from their participation in predicting the consequences of one''s locomotor actions. The strengths of this new theoretical viewpoint are discussed.