Psychosocial recommendations for the care of children and adults with epidermolysis bullosa and their family: evidence based guidelines.

Epidermolysis Bullosa (EB) is a group of rare genetic disorders resulting in skin fragility and other symptoms. Commissioned by DEBRA International and funded by DEBRA Norway, this evidence-bases guideline provides recommendations to optimise psychosocial wellbeing in EB.An international multidisciplinary panel of social and health care professionals (HCP) and people living with EB was formed. A systematic international literature review was conducted by the panel following the Scottish Intercollegiate Guidelines Network (SIGN) methodology. The resulting papers underwent systematic selection and critique processes. Included papers were allocated to 6 different outcome groups to allow data synthesis and exploration: quality of life, coping, family, wellbeing, access to HCP and pain. Based on the evidence in those papers, recommendations were made for individuals living with EB, family and caregivers and HCP working in the field.Few studies have investigated interventions and which factors lead to better outcomes, but general recommendations can be made. EB is a complex disease impacting enormously on every aspect of psychosocial life. People and families living with EB need access to multidisciplinary support, including psychological guidance, in order to improve quality of life and psychosocial wellbeing. Interventions should stimulate social participation to prevent isolation. People with EB and their families should be able to access a supportive network. HCP should be well supported and educated about the complexity of EB. They should work collaboratively with those around the individual with EB (e.g. schools, employers etc.) to provide psychosocial opportunity and care.Attention should be paid to the psychosocial impact of EB as well as physical needs. Directions for research are indicated.

Characterization of a novel esterase conferring insecticide resistance in the mosquito Culex tarsalis.

Resistance to the organophosphate insecticide, malathion, in a strain of Culex tarsalis mosquitoes is due to increased activity of a malathion carboxylesterase (MCE). To determine whether resistance was due to a qualitative or quantitative change in the MCE, the enzyme was purified from both malathion-resistant and -susceptible mosquitoes. Enzyme kinetic measurements revealed that the two strains have one MCE in common, but resistant mosquitoes also have a unique MCE which hydrolyses malathion 18 times faster. Interestingly, this MCE does not hydrolyse alpha-naphthyl acetate, a substrate commonly used to detect increased levels of esterases in other organophosphate-resistant insects. Unlike the over-produced esterase of some related mosquito species, each MCE in C. tarsalis accounts for only a small fraction (0.015%) of the total extractable protein in either strain. Therefore, resistance in these insects is due to the presence of a qualitatively different enzyme, and not to a quantitative increase of a non-specific esterase. This study therefore demonstrates that the underlying biochemical mechanisms of insecticide resistance in one insect cannot necessarily be predicted from those of another, even closely related species.

Isolation of an esterase conferring insecticide resistance in the mosquito Culex tarsalis.

Malathion resistance in a strain of Culex tarsalis mosquitoes is due primarily to the activity of a malathion carboxylesterase (MCE). The resistant strain was 150 times more resistant to malathion than the susceptible strain and was weakly resistant to malaoxon and carbaryl, but not to any other insecticide tested. The phenotype could be reversed with the carboxylesterase inhibitor triphenylphosphate, but no synergism was observed with either the phosphatase or polysubstrate monooxygenase inhibitors, NaF and piperonyl butoxide. MCE is expressed throughout development and is most concentrated in the gut tissues of the larvae. Subcellular fractionation indicated that MCE was localized primarily in the mitochondria of resistant insects and the cytoplasm of susceptible insects. The enzyme was purified to homogeneity from both strains, and has a molecular weight of 59,000. However, chromatofocusing indicated that resistant insects have two MCEs with pIs of 6.8 and 6.2, while susceptible insects possessed only one MCE with a pI of 6.8. The MCE unique to the resistant strain hydrolysed malathion 18 times faster than the MCE common to both strains, suggesting that malathion resistance in C. tarsalis is due to the presence of a qualitatively different esterase in the resistant strain.

Blood-feeding host preferences of the isomorphic species Simulium venustum and S. truncatum.

Animal-baited traps, using fox, mink, rabbits and ducks, were used in host preference experiments in two habitats (Beach and Woods). A generalized linear model of blood-feeding host preference is presented to test for significant differences between the isomorphic species Simulium venustum and Simulium truncatum. The S. truncatum population peaked before that of S. venustum. On any given day the two species divided their blood-feeding efforts among the different hosts in the same proportions. On the Beach, fox was the preferred host at the beginning of the season, but by the end of the season flies fed with equal frequency on the fox and the mink. In the Woods fox remained the preferred host throughout the season (late May to early July). Possible reasons for these feeding trends are discussed.

Effects of two blood-feeding regimes on mortality and female reproduction in a laboratory colony of stable flies, Stomoxys calcitrans.

Stable flies (Stomoxys calcitrans L.) deprived of a bloodmeal until 3 days post-emergence had higher mortality rates than control flies fed from the day of emergence. Fat bodies of deprived females required one more bloodmeal to reach maximum size, and maximum size was smaller, than fat bodies of control females. Ovarian development did not commence prior to feeding in deprived flies, and proceeded more slowly thereafter, resulting in a one blood-meal delay in egg maturation in deprived flies. Deprived females produced fewer (54.7, SD 2.8) eggs than controls (75.9, SD 3.7) and eggs from deprived females were smaller (mean length 684.0 microns) than control females' eggs (mean length 1165.7 microns).

Experimental infection of Aedes aegypti (Diptera: Culicidae) by the oral route with Sindbis virus.

The infectivity, dissemination, and transmissibility of wild-type Sindbis (SIN) virus were studied in Aedes aegypti (L). There was an initial decline in the viral titer of whole mosquitoes for 3 d after ingestion of virus, followed by a gradual increase to a maximal level by day 6. Immunoperoxidase staining of Ae. aegypti for viral antigen showed infection of midgut epithelial cells on day 1, of the fat body by day 3, and of the brain by day 4. By day 5, there was infection of the foregut, hindgut, Malpighian tubules, ovariole sheaths, Johnston's organ, thoracic ganglia, ventral nerve cord, and salivary glands. Viral antigen was not detected in the flight muscles and was found only in ovariole sheaths of the ovaries; germinal tissue was not infected. The transmission rate from SIN-infected Ae. aegypti to neonatal mice was 40%. A comparison of Ae. aegypti infected with SIN and with a neuroadapted strain of Sindbis virus (NSIN), which is more neurovirulent than SIN to mice after intracerebral inoculation, did not reveal significant differences in infectivity, dissemination, or transmissibility. The important differences between SIN and NSIN in a mouse model were not reflected in the infection of Ae. aegypti by the oral route.

Isolation, sequencing and characterization of two cDNA clones coding for trypsin-like enzymes from the midgut of Aedes aegypti.

In order to understand the regulation of trypsin genes by the blood meal, we constructed a cDNA library from mRNA isolated from midguts of blood-fed female Aedes aegypti. The library was screened with a Drosophila melanogaster trypsin-like gene; twelve cDNAs were isolated and sequenced. Two clones were 846 bp and 788 bp long with 762 bp and 716 bp open reading frames, respectively. The cDNAs were identified as coding for serine proteases by the presence of conserved serine, histidine and aspartic acid residues; the presence of an aspartate residue at position 176 suggests that the clones were derived from trypsin-like gene transcripts rather than chymotrypsin or other serine proteases. One of the clones contained a 5' untranslated region and coding regions for putative signal and activation peptides, suggesting that the product is secreted as an inactive zymogen and processed by autoactivation. Southern analysis of genomic DNA suggests that trypsin is encoded by a multigene family in A. aegypti.

Effects of α-Terthienyl on the midgut detoxification enzymes of the European corn borer,Ostrinia nubilalis.

The biochemical basis for the tolerance of the European corn borer,Ostrinia nubilalis, to the phototoxinα-terthienyl was investigated by measuring the midgut polysubstrate monooxygenases and glutathioneS-transferase activities.α-Terthienyl administered in the diet to the corn borers increased the level of cytochromeb 5, NADH-cytochromec reductase,O-demethylase, and glutathioneS-transferase activities. The induced detoxification enzyme activities should enable the corn borer to metabolizeα-terthienyl more efficiently and therefore render the corn borer highly tolerant toα-terthienyl.

The effects of artificial diets on the anterior intestinal cell ultrastructure of Rhodnius prolixus (Hemiptera:Reduviidae).

Mated female Rhodnius prolixus were fed diets of washed rabbit erythrocytes (RBC), rabbit plasma, edestin (a plant storage protein) in Ringer's or Ringer's solution alone. All diets contained 1 mM ATP. The effects of these diets on anterior intestinal cell ultrastructure were evaluated and compared to changes induced by normal blood feeding. Separation of basal labyrinth membranes was induced earlier after Ringer's-feeding than with all other diets. Normal modifications of the rough endoplasmic reticulum (rer) were observed only in response to blood components, while rer cisternae were swollen shortly after edestin feeding. Normal modifications to lysosomal structure were induced by plasma and RBC feeding, but changes were also observed with the non-blood diets. Production of extracellular membrane layers (ECML) by the microvilli occurred in response to each diet: plasma-feeding induced considerably early ECML formation, but prolonged ECML proliferation was greatest after RBC feeding. Storage inclusions were most prominent in cells of plasma-fed insects. Initial changes in the basal labyrinth may be induced by a high luminal fluid: protein ratio; in the rer by blood factor(s); and in lysosomes by plasma factor(s). Gut distention initiates ECML production but continued proliferation is regulated by the midgut contents.

Toxicity, localization and elimination of the phototoxin, alpha-terthienyl, in mosquito larvae.

Mosquito larvae were examined to determine interspecific and interstrain differences in susceptibility to the larvicidal effects of the plant-derived phototoxin, alpha-terthienyl (alpha-T). The LC50 values were as follows: Aedes aegypti, 4 ppb; Ae. epactius, 6 ppb; anopheles stephensi, 14 ppb; malathion-susceptible Culex tarsalis (S), 12 ppb; malathion-resistant Cx. tarsalis (R), 16 ppb. Fluorescence studies indicated localization of alpha-T in the midgut epithelium and in the lumen of Malpighian tubules. Rates of elimination of tritiated alpha-T differed significantly between Ae. aegypti and Cx. tarsalis (S) larvae. Rate of 3H-alpha-T elimination was inversely correlated with susceptibility to the toxic effects of the compound. The toxicological significance of selective alpha-T accumulation and the importance of alpha-T elimination in determining sensitivity are discussed.

The surface morphology of the midgut cells of Rhodnius prolixus Stål (Hemiptera: Reduviidae) during blood digestion.

The surface morphology of the midgut cells of Rhodnius prolixus is examined using scanning electron microscopy. Before feeding, the microvilli are devoid of any extracellular structures and can be observed in both fracture faces and surface views. By 3 days after feeding, patches of extracellular membrane layers are observed on the surface of the midgut cells and by 7 days the extracellular membrane layers form an incomplete sheet overlying the microvilli, such that the microvilli are no longer visible in surface view. At 15 days after the blood meal the membrane layers are well developed in the intestine forming a continuous sheet, while in the crop the layers are not as completely developed. The results complement previous studies on the midgut ultrastructure of R. prolixus. The extracellular membrane layers are thought to function as a peritrophic membrane, allowing the spatial separation of digestive processes.

Properties of Sindbis virus variants from infected Culex tarsalis mosquitoes.

Plaque-purified Sindbis virus was passed three times in Culex tarsalis mosquitoes and progeny viruses were isolated by plaque purification on a cloned line of Aedes albopictus cells. Nine of ten clones examined differed from wild-type (wt) virus with respect to their plaque morphology characteristics in chick embryo fibroblast (CEF) and/or A. albopictus cells. Seven clones were temperature-sensitive and failed to replicate or synthesize viral RNA in CEF cells at 41 degrees C. At 35 degrees C in CEF cells the majority of isolates synthesized less viral RNA than wt virus. In contrast, all cloned isolates synthesized viral RNA more rapidly than wild-type virus in A. albopictus cells.

Serological comparison of three strains of Aedes aegypti.

Young adults of three strains of the mosquito, Aedes aegypti, were compared serologically by means of the double-immunodiffusion technique. 1. Strains and sexes were serologically distinguishable. 2. Differences in antigenic composition were evident among the strains and sexes. 3. Degree of intraspecific serological relationship varied with sex.

Fate of ingested hepatitis B antigen in blood-sucking insects.

The fate of ingested hepatitis B antigen (HBsAg) in two mosquito species and two Hemiptera species was compared with the rate of blood meal digestion by these insects. In both mosquito species HBsAg was detected by radioimmunoassay for only a few hours after ingestion, disappearing well before the time of blood meal digestion. Production of a protease by the mosquito midgut may have been responsible for destruction of the antigen. In contrast, in the bedbug HBsAg remained detectable throughout a 5-week testing period. Moreover, titers rose during the last week, when blood meal digestion was complete, suggesting possible replication of the antigen. At no time was antigen detected in eggs or feces of any species tested, but juvenile bedbugs fed HBsAg when in the fourth or fifth instar stage still contained antigen after molting. These studies suggest that bedbugs may potentially be a more dangerous source of hepatitis B transmission than mosquitoes.