Factors limiting the domestic density of Triatoma infestans in north-west Argentina: a longitudinal study

Reported are the environmental and demographic risk factors associated with the domestic infestation and density of Triatoma infestans in three heavily infested rural villages in Santiago del Estero Province, Argentina. In a one-factor unadjusted analysis, the number of T. infestans captured per person-hour was associated significantly and negatively with the use of domestic insecticides by householders, type of thatch used in the roofs and the age of the house; and positively with the following: degree of cracking of the indoor walls and presence of hens nesting indoors. In one model, using multiple linear regression and a backward stepwise elimination procedure, most of the variation in the overall abundance of T. infestans was explained by insecticide use and the presence of hens nesting indoors; in another model using the same procedure it was explained by insecticide use, bug density in 1988 and previous spraying with deltamethrin in 1985. Variations in bug density per capture stratum (household goods, beds, walls and roof) were explained by the bug density in other strata and by one or two of the following risk factors: hens nesting indoors, type of roof, presence of cracks in the walls and number of people living in the house. Bug density might be locally controlled by the availability of refuges in the roofs and walls, by the presence of hens nesting indoors and by the use of domestic insecticides. Certain local materials, such as a grass known as simbol, could be successfully used in rural housing improvement programmes aimed at reducing the availability of refuges for insects in the roof.     

A comparison of biofilms from macrophytes and rocks for taste and odour producers in the St. Lawrence river.

Given their widespread and prolific annual development in the St. Lawrence River (SLR), macrophytes (i.e. submerged aquatic plants) represent large surface areas for biofilm growth and potentially important sites for associated production of taste and odour (T&O) compounds. We therefore evaluated the importance of submerged macrophytes and their associated biofilms for production of T&O compounds, 2-methylisoborneol (MIB) and geosmin (GM), compared with biofilms from adjacent rocks. We also tested the hypothesis that production of these compounds would differ between macrophyte species, based on the premise that they are not inert substrates but directly influence the communities that colonise their surfaces. Samples collected from transects across the SLR between Kingston and Cornwall, ON were dominated by the flat-bladed Vallisneria spp., and the leafed Myriophyllum spicatum, Elodea canadensis, Chara spp., Potamgeton spp., and Ceratophyllum spp. Overall, MIB and GM levels in biofilms ranged widely between samples. Expressed per g dry weight of biofilm, median levels from macrophyte were 50 (range 1-5000) ng MIB g(-1) and 10 (<1 to 580) ng GM g(-1) compared with 50 (range 5-970) ng MIB g(-1) and 160 (1-1600) ng GM g(-1) from rocks. Based on non-parametric statistical analysis, levels of GM were higher on a g dry weight basis in biofilms from rocks than macrophytes (P = 0.02), but MIB levels were similar (P = 0.94). However, when normalised for differences in substrate surface area (i.e. ng cm(-2)), levels of both MIB and GM were higher in biofilms from rocks than from macrophytes (P < 0.01). There were no discernable differences in MIB and GM concentrations from biofilms of different macrophytes based on either g dry weight sample or surface area (P > 0.05). Overlying water (OLW) concentrations ranged between 2-45 ng L(-1) for MIB and 5-30 ng L(-1) for GM and were not correlated with levels in adjacent biofilms. However, OLW concentrations peaked in shallow, low energy embayments consistent with enhanced production and release of MIB and GM in nearshore areas. The results support our previous work showing the importance of biofilms on various surfaces (rocks, macrophytes and zebra mussels) for MIB and GM production in the SLR, but suggest that inert surfaces like rocks are more productive sites per unit surface area than macrophytes.     

Off flavours in large waterbodies: physics, chemistry and biology in synchrony.

The Laurentian Great Lakes of North America are a drinking water source for millions of Canadian and US consumers. These waterbodies have undergone extensive change over the past century as a result of widespread degradation and remediation. Many of the Lakes are prone to taste and odour (T&O), and although these outbreaks have been poorly monitored, evidence suggests that they are increasing in frequency. Tracing and controlling T&O in such large systems presents a challenging task, due to their physical size and complexity. This paper presents an overview of recent investigative and management approaches to T&O in Lake Ontario and its outflow, the St. Lawrence River. We have identified three distinct patterns of T&O in these source-waters, caused by geosmin and 2-methylisoborneol and differing in their planktonic and benthic sources, and temporal and spatial dynamics. Each pattern has required a different approach by scientists and management, in partnership with the water industry. We have shown these T&O outbreaks are caused and moderated by physical, chemical and biological mechanisms over a spectrum of spatial and temporal scales. Canadian municipalities affected by these outbreaks have been key to the investigation of the links between T&O and ecosystem processes with the aim to develop more proactive water treatment and long-term management.     

StoryGrid [educational computing]

The StoryGrid project undertook studying the role new interface technologies might play in education, particularly at the high school level. Unfortunately, technology often seizes center stage in high school classrooms; i.e., it becomes the topic of instruction. We believe that learning about technology would be most successful when technology is not the topic, but simply a tool used during instruction. StoryGrid, therefore, was designed to support and to enhance existing narrative activity in classrooms by adhering to the following goals: trigger reflection and interpretation, accommodate individual expression and encourage student discourse.     

Chronic effects of glucose on insulin signaling in A-10 vascular smooth muscle cells

To examine the effects of hyperglycemia on insulin signaling in A-10 vascular smooth muscle cells, cells were treated with extracellular D-glucose and effects of insulin were studied on the diacylglycerol-protein kinase C signaling system. A-10 cells specifically bound 125I-insulin, and insulin-like growth factor-I did not displace the label. 125I-insulin binding was unaltered under hyperglycemic conditions. To determine if insulin receptors were coupled to other insulin-regulated processes, diacylglycerol, protein kinase C, and glucose transport were evaluated. Insulin increased cellular diacylglycerol (DAG) levels which were also increased following glucose treatment and not further stimulated by insulin. The uptake of 2-[3H]deoxy-D-glucose (2-DOG) was stimulated by insulin and 12-O-tetradecanoyl phorbol 13-acetate (TPA). Insulin- and TPA-stimulated 2-[3H]DOG uptake was inhibited by a protein kinase inhibitor, staurosporine. Preincubation of cells with 500 nM TPA overnight resulted in the inhibition of insulin- and TPA-stimulated 2-[3H]DOG uptake. Protein kinase C activity was translocated from cytosolic to membrane fractions following insulin treatment. Overnight glucose (25 mM) treatment resulted in a 50% decrease in protein kinase C enzyme activity and > 90% decrease in protein kinase C beta immunoreactive levels. Protein kinase C activity and levels were not affected by osmotic control media containing mannitol. A-10 cells express GLUT4-type glucose transporters. Neither insulin-regulatable glucose transporter (GLUT4) mRNA nor GLUT4 protein levels were diminished by glucose. Significant decreases in insulin- and TPA-stimulated 2-[3H]DOG uptake occurred, however, with glucose. The down-regulation of protein kinase C beta and resultant inhibition of 2-[3H]DOG uptake by chronic glucose suggests a biochemical link between hyperglycemia and DAG-protein kinase C signaling in vascular smooth muscle cells.     

Clinical pharmacokinetics of mycophenolate mofetil

The pharmacokinetics of the immunosuppressant mycophenolate mofetil have been investigated in healthy volunteers and mainly in recipients of renal allografts. Following oral administration, mycophenolate mofetil was rapidly and completely absorbed, and underwent extensive presystemic de-esterification. Systemic plasma clearance of intravenous mycophenolate mofetil was around 10 L/min in healthy individuals, and plasma mycophenolate mofetil concentrations fell below the quantitation limit (0.4 mg/L) within 10 minutes of the cessation of infusion. Similar plasma mycophenolate mofetil concentrations were seen after intravenous administration in patients with severe renal or hepatic impairment, implying that the de-esterification process had not been substantially affected. Mycophenolic acid, the active immunosuppressant species, is glucuronidated to a stable phenolic glucuronide (MPAG) which is not pharmacologically active. Over 90% of the administered dose is eventually excreted in the urine, mostly as MPAG. The magnitude of the MPAG renal clearance indicates that active tubular secretion of MPAG must occur. At clinically relevant concentrations, mycophenolic acid and MPAG are about 97% and 82% bound to albumin, respectively. MPAG at high (but clinically realisable) concentrations reduced the plasma binding of mycophenolic acid. The mean maximum plasma mycophenolic acid concentration (Cmax) after a mycophenolate mofetil 1 g dose in healthy individuals was around 25 mg/L, occurred at 0.8 hours postdose, decayed with a mean apparent half-life (t1/2) of around 16 hours, and generated a mean total area under the plasma concentration-time curve (AUC infinity) of around 64 mg.h/L. Intra- and interindividual coefficients of variation for the AUC infinity of the drug were estimated to be 25% and 10%, respectively. Intravenous and oral administration of mycophenolate mofetil showed statistically equivalent MPA AUC infinity values in healthy individuals. Compared with mycophenolic acid, MPAG showed a roughly similar Cmax about 1 hour after mycophenolic acid Cmax, with a similar t1/2 and an AUC infinity about 5-fold larger than that for mycophenolic acid. Secondary mycophenolic acid peaks represent a significant enterohepatic cycling process. Since MPAG was the sole material excreted in bile, entrohepatic cycling must involve colonic bacterial deconjugation of MPAG. An oral cholestyramine interaction study showed that the mean contribution of entrohepatic cycling to the AUC infinity of mycophenolic acid was around 40% with a range of 10 to 60%. The pharmacokinetics of patients with renal transplants (after 3 months or more) compared with those of healthy individuals were similar after oral mycophenolate mofetil. Immediately post-transplant, the mean Cmax and AUC infinity of mycophenolic acid were 30 to 50% of those in the 3-month post-transplant patients. These parameters rose slowly over the 3-month interval. Slow metabolic changes, rather than poor absorption, seem responsible for this nonstationarity, since intravenous and oral administration of mycophenolate mofetil in the immediate post-transplant period generated comparable MPA AUC infinity values. Renal impairment had no major effect on the pharmacokinetic of mycophenolic acid after single doses of mycophenolate mofetil, but there was a progressive decrease in MPAG clearance as glomerular filtration rate (GFR) declined. Compared to individuals with a normal GFR, patients with severe renal impairment (GFR 1.5 L/h/1.73m2) showed 3-to 6-fold higher MPAG AUC values. In rental transplant recipients during acute renal impairment in the early post-transplant period, the plasma MPA concentrations were comparable to those in patients without renal failure, whereas plasma MPAG concentrations were 2- to 3-fold higher. Haemodialysis had no major effect on plasma mycophenolic acid or MPAG. Dosage adjustments appear to not be necessary either in renal impairment or during dialysis. (ABSTRACT TRUN     

Relationship between expression of epidermal growth factor and simian virus 40 T antigen in a line of transgenic mice

The pattern of expression of the simian virus 40 (SV40) T antigen gene and resultant dysplasia were re-examined in a line of transgenic mice in which the T antigen gene was under the control of the SV40 early promoter. We found that T antigen expression in the kidney, and resulting dysplastic lesions, occurred exclusively in the distal convoluted tubules and the ascending limbs of Henle. Epidermal growth factor (EGF) expression in the kidney of normal mice was similarly immunolocalized. The correlation between high EGF immunoreactivity in normal mouse tissues and T antigen expression in the transgenic counterpart was also seen in the choroid plexus epithelium and in the submandibular glands of male mice. T antigen was not found in the submandibular gland of transgenic females. Similarly, EGF was only rarely detected in the normal female submandibular gland. In contrast to the correlation between T antigen expression in the transgenic mice and EGF expression in the corresponding tissues of the normal mice, within the dysplastic lesions of the transgenic mice EGF expression was severely diminished. Adenocarcinomas of the male submandibular gland from another line of transgenic mice that expresses the Int-1 transgene, showed similarly reduced levels of immunostaining for EGF. Thus, reduced expression of EGF might be a general feature of dysplasia and tumorigenesis in those tissues that normally express EGF.