Risk of tuberculosis reactivation during interleukin-17 inhibitor therapy for psoriasis: a systematic review

Immunosuppressive therapies, effective in treating inflammatory disorders such as psoriasis, increase the risk of serious infections, such as tuberculosis (TB). For example, tumour necrosis factor (TNF)-alpha inhibitors significantly increase the risk of TB reactivation in patients with latent TB infection (LTBI), which has led clinicians to routinely test for TB prior to initiation of these medications. This protocol has since extended to other, newer immunomodulatory therapies for psoriasis, such as interleukin (IL)-17 inhibitors, including secukinumab, ixekizumab and brodalumab. We conducted a systematic review to examine whether there is any evidence that IL-17 inhibitor therapy for psoriasis increases the risk of TB reactivation. Using PubMed and EMBASE, our literature search resulted in 139 total articles. After manually reviewing each article for the discussion of IL-17 inhibitors for psoriasis, with data originating from clinical trials, and assessment for incidence of TB reactivation, 23 articles met the full inclusion criteria for our review. Overall, we found no cases of TB reactivation in patients treated with IL-17 inhibitors for psoriasis. This suggests that IL-17 inhibitors may be safely used in psoriasis patients with LTBI who receive appropriate LTBI treatment. However, long-term real-world studies are warranted to further evaluate this risk.

Reduced alpha-defensin expression is associated with inflammation and not NOD2 mutation status in ileal Crohn's disease

BACKGROUND AND AIMS

Reduced ileal Paneth cell alpha-defensin expression has been reported to be associated with Crohn's disease, especially in patients carrying NOD2 mutations. The aim of this study was to independently assess whether NOD2, alpha-defensins and Crohn's disease are linked.

METHODS

Using quantitative real-time polymerase chain reaction (RT-PCR), we measured the mRNA expression levels of key Paneth cell antimicrobial peptides (DEFA5, DEFA6, LYZ, PLA2G2A), inflammatory cytokines [interkelukin 6 (IL6) and IL8], and a marker of epithelial cell content, villin (VIL1) in 106 samples from both affected ileum (inflamed Crohn's disease cases, n = 44) and unaffected ileum (non-inflamed; Crohn's disease cases, n = 51 and controls, n = 11). Anti-human defensin 5 (HD-5) and haematoxylin/eosin immunohistochemical staining was performed on parallel sections from NOD2 wild-type and NOD2 mutant ileal Crohn's disease tissue.

RESULTS

In Crohn's disease patients, DEFA5 and DEFA6 mRNA expression levels were 1.9- and 2.2-fold lower, respectively, in histologically confirmed inflamed ileal mucosa after adjustment for confounders (DEFA5, p<0.001; DEFA6, p = 0.001). In contrast to previous studies, we found no significant association between alpha-defensin expression and NOD2 genotype. HD-5 protein data supports these RNA findings. The reduction in HD-5 protein expression appears due to surface epithelial cell loss and reduced Paneth cell numbers as a consequence of tissue damage.

CONCLUSIONS

Reduction in alpha-defensin expression is independent of NOD2 status and is due to loss of surface epithelium as a consequence of inflammatory changes rather than being the inciting event prior to inflammation in ileal Crohn's disease.

Removal of N-terminal blocking groups from proteins

Two enzymatic methods commonly used in N-terminal sequence analysis of blocked proteins are presented in this unit; one uses pyroglutamate aminopeptidase for N(alpha)-pyrrolidone carboxyl-proteins in solution or blotted onto a membrane, and the other uses acylaminoacyl-peptide hydrolase for N(alpha)-acyl-proteins blocked with other acyl groups. A Support Protocol describes a colorimetric assay for pyroglutamate aminopeptidase activity. Sequencing with acylaminoacyl-peptide hydrolase must include fragmentation of the protein before unblocking can be carried out, so procedures are provided for chemically blocking newly generated peptides with either succinic anhydride or phenylisothiocyanate/performic acid. The hydrolase is then applied to the total mixture of peptides, only one of which, the acylated N-terminal peptide, should be a substrate for hydrolase. After incubation, the mixture of peptides is subjected to sequence analysis. Protocols are also provided for unblocking N-terminally blocked proteins using acid-catalyzed hydrolysis or methanolysis, hydrazinolysis, and beta-elimination after acid-catalyzed N-O shift. Alternate protocols describe chemical removal of acetyl and longer-chain alkanoyl groups, as well as formyl groups to open the cyclic imide of pyrrolidone carboxylate.

Angiotensinogen and transforming growth factor beta1: novel genes in the pathogenesis of Crohn's disease

BACKGROUND

Angiotensin peptides may act locally as cytokines in several organ systems with elevated mucosal levels present in Crohn's disease. A variant in the angiotensinogen gene promoter results in increased peptide production, while transforming growth factor beta1 (TGFbeta1) codon 25 variants demonstrate variable peptide production, predisposing to fibrosis in several organs.

AIMS

Conduct an Australian-based analysis of the angiotensinogen-6 variant in two independent inflammatory bowel disease (IBD) cohorts, and examine the role of angiotensinogen-6 and TGFbeta1 codon 25 variants in shaping Crohn's disease phenotype.

METHODS

IBD Patients (Crohn's disease = 347, ulcerative colitis = 147) and CD families (n = 148) from two cohorts, together with 185 healthy controls were genotyped for angiotensinogen-6. Genotype-phenotype analyses were performed for both angiotensinogen-6 and TGFbeta1 codon 25.

RESULTS

Angiotensinogen-6 AA genotype was significantly associated with Crohn's disease (p = 0.007, OR = 2.38, CI = 1.32-4.32) in cohort 1, but not in the smaller cohort 2 (p = 0.19). The association remained significant when the two cohorts were combined (p = 0.008), and in a TDT family analysis (p = 0.03). TGF 1 codon 25 was associated with stricturing Crohn's disease (p = 0.01, OR = 2.63, CI = 1.16-5.88) and a shorter time to intestinal resection (p = 0.06).

CONCLUSIONS

The association of the angiotensinogen-6 variant with Crohn's disease supports a potential role for angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists in disease treatment.

TNFalpha and IL10 SNPs act together to predict disease behaviour in Crohn's disease

BACKGROUND

The cytokines tumour necrosis factor (TNF)alpha and interleukin (IL)10 have been implicated in the pathogenesis of Crohn's disease (CD), with increased concentrations reported in patients with active disease. However, limited data exist on their effects on disease phenotype in the same population. Certain single nucleotide polymorphisms (SNPs) within the promoter region of the IL10 (-1082G/A, -592C/A) and TNFalpha (-308G/A, -857C/T) genes have been associated with altered levels of circulating IL10 and TNFalpha.

METHODS

We conducted an Australian based case-control study (304 CD patients; 231 healthy controls) of these four SNPs. Further investigation of two SNPs was conducted using a logistic regression analysis.

RESULTS

We identified a possible association of both IL10 SNPs and TNFalpha-857 with CD. Further investigation of a relationship with disease severity showed a significant association of higher producing IL10-1082G and TNFalpha-857C alleles with stricturing behaviour, which was strongest when these alleles were combined and persisted after multivariate analysis (p = 0.007; odds ratio (OR) 2.37, 95% CI 1.26 to 4.43). In addition, the TNFalpha-857CC genotype was independently associated with familial CD (p = 0.03; OR 3.12; 95% CI 1.15 to 8.46).

CONCLUSION

These two SNPs may help to predict disease behaviour in CD patients, which may be clinically useful in shaping treatment of the disease at an earlier stage.

Orally administered Giardia duodenalis extracts enhance an antigen-specific antibody response

We have identified novel adjuvant activity in specific cytosol fractions from trophozoites of Giardia isolate BRIS/95/HEPU/2041 (J. A. Upcroft, P. A. McDonnell, and P. Upcroft, Parasitol. Today, 14:281-284, 1998). Adjuvant activity was demonstrated in the systemic and mucosal compartments when Giardia extract was coadministered orally with antigen to mice. Enhanced antigen-specific serum antibody responses were demonstrated by enzyme-linked immunosorbent assay to be comparable to those generated by the "gold standard," mucosal adjuvant cholera toxin. A source of adjuvant activity was localized to the cytosolic component of the parasite. Fractionation of the cytosol produced fraction pools, some of which, when coadministered with antigen, stimulated an enhanced antigen-specific serum response. The toxic component of conventional mucosal adjuvants is associated with adjuvant activity; therefore, in a similar way, the toxin-like attributes of BRIS/95/HEPU/2041 may be responsible for its adjuvanticity. Complete characterization of the adjuvant is under way.

Analytical laboratory quality: Part I. General quality practices

Once a biotechnology product reaches the final stages of development, the types of quality practices required in the laboratories performing the analytical testing are clearly defined in the applicable regulations. Long before this stage, though, there are innumerable tests and studies conducted in biomolecular facilities that provide critical information upon which product development decisions are made. While sound scientific practices will guide the management of the best of these laboratories, there are several additional operational elements that can significantly enhance the utility of the data to commercial clients. Such laboratory quality practices can also provide considerable benefit to the facility itself, engendering higher confidence in the day-to-day operations within the laboratory. Most of these practices can be simply implemented with pens, notebooks, and diligence.

Oral tolerance: elucidation of mechanisms and application to treatment of autoimmune diseases

Oral tolerance is the phenomenon of systemic, antigen specific, immunological hyporesponsiveness that results from oral administration of a protein. The mechanism by which tolerance is generated depends on the amount of antigen administered; low doses favor induction of regulatory T cells while higher doses favor clonal deletion and anergy. The regulatory T cells induced by low doses of oral antigen are triggered by the same antigen to secrete cytokines that suppress, in an antigen nonspecific manner, inflammation in the microenvironment where the triggering antigen is located. This makes possible the targeted delivery of antiinflammatory cytokines to a specific tissue without the requirement for identifying the antigen causing the inflammation. This attribute makes active suppression an attractive mechanism for developing therapies for autoimmune diseases. Orally administered autoantigens have been shown to suppress a wide variety of experimental autoimmune diseases and have recently been applied to the treatment of human autoimmune diseases with promising early results.

Genetic diversity and gene flow among southeastern Queensland koalas (Phascolarctos cinereus)

Habitat fragmentation and destruction associated with the rapid urban and rural development of southeast Queensland presents an immediate threat to the survival of koala populations within this region. A sensitive method combining heteroduplex analysis (HDA) with temperature gradient gel electrophoresis (TGGE) was optimized to detect within-species variation in a mitochondrial DNA (mtDNA) control-region fragment, approximately 670 bp in length, from the koala. Eight different haplotypes were characterized in koalas, of which four were novel. Analysis of mtDNA diversity in 96 koalas from five populations in southeast Queensland revealed that the number of haplotypes in a single population ranged from one to five, with an average within-population haplotype diversity of 0.379 +/- 0.016, and nucleotide diversity of 0.22 +/- 0.001%. Nucleotide divergence between populations averaged 0.09 +/- 0.001% and ranged from 0.00 to 0.14%. Significant genetic heterogeneity was observed among most populations, suggesting that koala populations may be spatially structured along matrilines, although this may not be universal. The limited distribution of the central phylogenetic haplotype suggested the possibility of historical population bottlenecks north of the Gold Coast, while the presence of two highly divergent haplotypes at the Moreton site may indicate the occurrence of one or more undocumented translocation events into this area.

The built environment as a component of quality care: understanding and including the patient's perspective

BACKGROUND

Although there has been little systematic assessment of how the built environment of health care facilities affects the quality of care, the built environment is a major element of structure of care--one of three facets of quality. Yet in contrast to the growing trend of using consumer perceptions of both processes and outcomes of care in QI activities, quality assessments of the structure of care do not currently rely on patient feedback. PURPOSE OF PROJECT: During the initial phase of a multiphase project, nine focus groups were conducted in 1997 to identify the salient dimensions of experience from the patient's perspective. The content of these focus groups guided the development of assessment tools in the second phase of the project, which began in February 1998.

FINDINGS

Participants in three focus groups that were held in each of three settings--ambulatory care, acute care, and long term care--described in detail a variety of reactions to the built environment. Analysis revealed eight consistent themes in what patients and family member consumers look for in the built environment of health care. In all three settings, they want an environment, for example, that facilitates a connection to staff and caregivers, is conducive to a sense of well-being, and facilitates a connection to the outside world.

DISCUSSION

Data derived from the focus group research has guided the development of quantitative survey and assessment tools. For each setting, patient-centered checklists and questionnaires are designed to help institutions set priorities for the improvement of facility design from the patient's perspective.

Wound care for persons with diabetes

This article addresses local wound care in people with diabetes mellitus. An approach is proposed that uses wound depth and color to determine the goals of local wound treatment. Principles of cleansing, debridement, and the use of moisture retentive dressings are discussed. Infection, a significant problem in the diabetic patient, is addressed as an essential part of local wound care in these patients.

Phylogeographic differentiation in the mitochondrial control region in the koala, Phascolarctos cinereus (Goldfuss 1817)

The koala, Phascolarctos cinereus, is a geographically widespread species endemic to Australia, with three currently recognized subspecies: P.c. adustus, P.c. cinereus, and P.c. victor. Intraspecific variation in the mitochondrial DNA (mtDNA) control region was examined in over 200 animals from 16 representative populations throughout the species' range. Eighteen different haplotypes were defined in the approximately 860 bp mtDNA control region, as determined by heteroduplex analysis/temperature gradient gel electrophoresis (HDA/TGGE). Any single population typically possessed only one or two haplotypes yielding an average within-population haplotypic diversity of 0.180 +/- 0.003, and nucleotide diversity of 0.16%. Overall, mtDNA control region sequence diversity between populations averaged 0.67%, and ranged from 0% to 1.56%. Nucleotide divergence between populations averaged 0.51%, and ranged from 0% to 1.53%. Neighbour-joining methods revealed limited phylogenetic distinction between geographically distant populations of koalas, and tentative support for a single evolutionarily significant unit (ESU). This is consistent with previous suggestions that the morphological differences formalized by subspecific taxonomy may be interpreted as clinal variation. Significant differentiation in mtDNA-haplotype frequencies between localities suggested that little gene flow currently exists among populations. When combined with microsatellite analysis, which has revealed substantial differentiation among koala populations, we conclude that the appropriate short-term management unit (MU) for koalas is the local population.

Managing diabetic foot ulcers

This article discusses optimal care for a diabetic foot wound including use of a protocol with standards for assessment, treatment, and prevention. Patient and family education is also pivotal to the plan's success.

Randomly amplified polymorphic DNA variation in populations of eastern Australian koalas, Phascolarctos cinereus

Randomly amplified polymorphic DNA (RAPD) variation in populations of the koala, Phascolarctos cinereus, was investigated, revealing significant differences in the level of diversity between southern and northern regions of eastern Australia. Of the 20 polymorphic RAPD markers identified in koalas, 4-7 were polymorphic in southern populations, while 12-17 were polymorphic in northern populations. Analysis of molecular variance revealed a significant difference in the estimated variance between koalas from northern and those from southern regions (P < 0.001), where populations from the north were greater than twice as variable as their southern cousins. The total genetic diversity observed was attributed to regional differences (30.91%), population differences within a region (11.77%), and differences among individuals within a population (57.32%). For the within-region analyses, a large proportion of the genetic diversity was attributable to individual differences within a population, 80.34% for the north and 91.23% for the south. These results demonstrate that RAPD markers are useful for determining population structure among koalas.

Wound infection: a nurse's perspective

There is clinical uncertainty about the involvement of bacteria in open wounds. Frequently asked questions are: Is this wound infected? Should I culture the wound? How should I clean the wound? Do I need to use sterile technique when I perform local wound care? Using available science and common sense, a practical approach is proposed to answer these questions.

Genetic variation in captive koalas (Phascolarctos cinereus): parentage determination and individual identification

Highly repeatable randomly amplified polymorphic DNA (RAPD) markers were developed for parentage studies in the koala (Phascolarctos cinereus). Of the 25 RAPD primers screened, 5 (20.0%) produced 32 repeatable polymorphic RAPD bands (average/primer = 6.4 +/- 4.2). A high level of polymorphism was observed for each group of koalas (Featherdale, 71.9%; Lone Pine, 84.4%). All 25 koalas could be uniquely identified using either RAPD or microsatellite markers. Of the 32 RAPD markers generated in koalas, 25 were informative for parentage analyses. These RAPD markers successfully determined both parents to three offspring and a male parent to a fourth offspring. Paternity analysis (where the female parent is known) succeeded in assigning the correct male parent to seven offspring. Our RAPD-PCR method generates informative genetic markers that are useful for parentage determination and individual identification of captive koalas. This would provide genetic analysis to zoos and wildlife parks as a low-cost alternative to the more expensive microsatellite markers.

Comparing claims data and self-reported data with the medical record for Pap smear rates

The objective of this study was to assess and compare the relative accuracy of claims data and patient self-reported information with medical records for Pap smear rates. A retrospective analysis of information obtained from administrative claims files, patient medical records, and a telephone survey was performed of 400 women age 19 through 75 years who were randomly selected for participation in the study. The data were obtained from a large multispecialty group practice in Minneapolis, Minnesota for the study years 1991 through 1993. Information from administrative claims regarding Pap smear status corresponded highly with information in the medical record (sensitivity 95% or higher; specificity 95% or higher; kappa 0.896 or better). Self-reported information from the telephone survey did not correspond well with medical record information nor with results in administrative claims.

Energy expenditure during walking by children who have proximal femoral focal deficiency

The energy expended during walking by sixteen children who had proximal femoral focal deficiency was measured to compare the outcomes after Syme amputation (seven subjects) with those after Van Nes rotational osteotomy (nine subjects). Multivariate regression analysis revealed that the subjects who had had a Van Nes procedure had a mean oxygen cost (energy per unit of body mass expended per distance walked) that was 0.12 milliliter per kilogram of body mass per meter lower than that of the subjects who had had a Syme amputation (p = 0.001). The subjects who had had a Van Nes procedure tended to walk faster (p = 0.07). A significant decrease in the oxygen cost as a function of increasing age was observed for both groups (p < 0.0001, r2= 0.79). We believe that the reduced energy expenditure associated with the Van Nes rotational osteotomy is one of several factors to consider when deciding which operation should be done for children who have proximal femoral focal deficiency.

Taking health status into account when setting capitation rates: a comparison of risk-adjustment methods

OBJECTIVE

To compare performance of different health status measures for risk-adjusting capitation rates.

DESIGN

Cross-sectional study. Health status measures derived from 1 year were used to predict resources for that year and the next.

SETTING

Group-network health maintenance organization in Minnesota.

PARTICIPANTS

Sample of 18- to 64-year-old (n=3825) and elderly (aged > or = 65 years; n=1955) members enrolled in a network-model health maintenance organization in Minnesota.

MAIN OUTCOME MEASURES

Total expenditures in the year concurrent with the health status survey (July 1991 through June 1992) and total expenditures in the year following the survey (July 1992 through June 1993).

RESULTS

Capitation adjustment based on demographic measures performed least well. Both self-reported health status measures and diagnoses predicted future expenditures twice as well as demographics. When predicting costs for groups of patients rather than individuals, the demographic model worked well for average groups but tended to overpredict healthier groups and underpredict sicker groups. Ambulatory Care Groups based on diagnoses performed better than self-reported health status both in the retrospective models and across healthier and sicker groups.

CONCLUSIONS

Without risk adjustment, capitation rates are likely to overpay or underpay physicians for certain patient groups. It is possible to improve prediction using health status measures for risk adjustment. When selection bias is suspected and administrative data are available, we recommend a risk-adjustment method based on diagnostic information. If diagnostic data are not available, we recommend a system based on simple self-reported measures, such as chronic conditions, rather than complex functional status measures.

Physical therapy to improve functioning of older people in residential care facilities

BACKGROUND AND PURPOSE

The purpose of this study was to determine the effectiveness of an individualized physical therapy mobility training program on the gait, balance, and functional performance of elderly individuals living in residential care facilities.

SUBJECTS

Twenty-seven elderly individuals with impaired balance and difficulty performing at least one functional activity participated in the study. The subjects ranged in age from 71 to 97 years (mean = 87.1, SD = 6.7).

METHODS

Balance and gait speed were assessed at baseline and following physical therapy that consisted of exercises to improve specific functional limitations. Outcomes were reassessed 1 month following completion of the physical therapy.

RESULTS

Gait and balance outcomes were analyzed using a one-way repeated-measures analysis of variance. Improvement was obtained in balance, which was maintained at 1 month follow-up. Gait speed did not improve to a level of statistical significance.

CONCLUSION AND DISCUSSION

After physical therapy, subjects improved in balance and functional performance. An improvement in gait speed may require a longer duration of treatment.

Using wound debridement to help achieve the goals of care

The removal of devitalized tissue, particulate matter, or foreign materials from a wound, debridement, is often the first goal of wound care. Debridement can be accomplished surgically (instrument/sharp), chemically, mechanically or by means of autolysis. Each procedure has distinct advantages, disadvantages, indications for use and risks, and a combination of methods will often expedite the process while limiting the chance of complications. Depending on the method used as well as a variety of local and systemic factors, chronic wound debridement can take anywhere from a few days to more than a month. Even though wound debridement is often discussed separately, particularly when managing patients with chronic wounds, it should not be viewed in isolation. Rather, it is one aspect of total patient care. Measures to facilitate the healing process in general should be employed at all times, because debridement and wound healing can occur simultaneously.

Screening for balance and mobility impairment in elderly individuals living in residential care facilities

BACKGROUND AND PURPOSE

The rapid growth of the elderly population has resulted in a corresponding rise in the number of elderly individuals who experience disability during their lifetimes. The purpose of this study was to test the usefulness of four established clinical measures of balance, gait, and subjective perceptions of fear of falling as screening methods for referring community-dwelling elderly individuals living in residential care facilities for detailed physical therapy evaluation and possible intervention.

SUBJECTS

The subjects were a convenience sample of 53 elderly individuals living in two residential care facilities for the elderly.

METHODS

Subjects were tested on each of four clinical measures of balance and mobility. Their performance on these measures was compared with a physical therapist's brief evaluation of disability and appropriateness for more detailed evaluation. The usefulness of these tools as screening methods was determined by calculating sensitivity and specificity levels using the physical therapist's evaluation as a standard.

RESULTS

The sensitivity and specificity levels of the four clinical measures in their application as screening tests for referral to physical therapy were as follows: Berg Balance Scale, 84% and 78%; balance subscale of the Tinetti Performance-Oriented Mobility Assessment, 68% and 78%; gait speed, 80% and 89%; and Tinetti Fall Efficacy Scale, 59% and 82%. The combination of two tests, Berg Balance Scale and gait speed, yielded the highest sensitivity of 91% and the highest specificity of 70% when a subject tested positive on at least one test.

CONCLUSION AND DISCUSSION

These findings indicate the feasibility of developing screening methods for referring community-dwelling elderly individuals for a detailed physical therapy evaluation based on established clinical assessment measures, with a combination of tests measuring balance and gait demonstrating the most promising results.

Biotechnology core facilities: trends and update

A survey of 128 biotechnology core facilities has provided data on the finances, services, space requirements, and personnel. An average facility had four full-time personnel and 7.5 major instrument systems, and occupied 969 sq. ft. Average total income was $244,000/year, but annual user fee income was only $125,000. Typically, facilities required substantial institutional support or grants. Cost recovery (user fee income divided by total income) averaged 49%. During the last 5 years user fee income, total income, and cost recovery have increased. In-house charges for protein sequencing and peptide synthesis increased approximately 30%, while oligonucleotide synthesis charges decreased by 74%. The costs (charges corrected for subsidy from non-user fee income) for most services did not significantly change, except that oligonucleotide synthesis costs decreased by 25% in 1992. DNA synthesis had the highest throughout per month (116 samples), followed by amino acid analysis (86 samples) and DNA sequencing (67 samples). Other services averaged from 5 to 60 samples. DNA synthesis and purification were the services used by the greatest number of principal investigators. A number of services including DNA sequencing, mass spectrometry, capillary electrophoresis, RNA synthesis, electroblotting, and carbohydrate analysis have been introduced in the last 3 years. Although these services are characterized by high levels of methods development and non-user runs, they are offered by twice the percentage of facilities as in 1989, and are increasingly contributing to facility income.

Depressant insect selective neurotoxins from scorpion venom: chemistry, action, and gene cloning

The present study examines the similarity in the symptoms and binding properties between the depressant and excitatory insect-selective neurotoxins, derived from scorpion venom. A comparison of their primary structures and neuromuscular effects is presented. A new depressant toxin (LqhIT2) was purified from the venom of the scorpion Leiurus quinquestriatus hebraeus. The effects of this toxin on a prepupal housefly neuromuscular preparation mimic its effects on the intact insect, i.e, a brief period of repetitive bursts of regular junction potentials (JPs) is followed by reduced amplitude JPs ending with a block of the neuromuscular transmission. "Loose" patch clamp recordings indicate that the repetitive activity has a presynaptic origin (the motor nerve) and resembles the effect of the excitatory toxin AaIT. The final synaptic block is supposed to be the end result of neuronal membrane depolarization. Such an effect is not caused by an excitatory toxin, which induces long "trains" of repetitive firing. The amino acid sequences of three depressant toxins were determined by automatic Edman degradation indicating a high degree of sequence homology. This conservation differs from those of other groups of scorpion toxins. The opposing pharmacological effects of depressant toxins are discussed in light of the above neuromuscular effects and sequence analysis. A genetic approach in the study of the structure-function relationships of the depressant toxins was initiated by isolating cDNA clones encoding the LqhIT2 and BjIT2 toxins. Their sequence analysis revealed the precursor form of these toxins: A 21 amino acid residue signal peptide followed by a 61 amino acid region of the mature toxin, and three additional amino acids at the carboxy terminus.

Development of recombinant viral insecticides by expression of an insect-specific toxin and insect-specific enzyme in nuclear polyhedrosis viruses

As supplements to classical chemical insecticides, two approaches to develop recombinant baculovirus insecticides are described. In one approach an insect-specific toxin is expressed leading to a dramatic reduction in time to death. In the second approach an insect juvenile hormone esterase is expressed which leads to a reduction in feeding. Modifications of the wildtype esterase led to viruses which reduced the time to death as effectively as did the toxin-expressing virus. In both cases existing recombinant viruses are viewed as leads, and approaches to further improvement in the engineered viruses are suggested. Many of these approaches are based on analogy with the development of classical synthetic insecticides. Using these viruses as examples, the potential utility and limitations of recombinant viruses and other biological insecticides are discussed.

Development of a recombinant baculovirus expressing an insect-selective neurotoxin: potential for pest control

Recombinant nuclear polyhedrosis viruses (NPVs) expressing insect-selective toxins, hormones, or enzymes could enhance their insecticidal properties. We have constructed a recombinant, polyhedrin-positive Autographa californica NPV (AcNPV) that is orally infectious and expresses an insect-selective toxin (AaIT), isolated from the scorpion Androctonus australis, under the control of the p10 promoter. Bioassays with the recombinant baculovirus on 2nd instar larvae of Heliothis virescens demonstrated a significant decrease in the time to kill (LT50 88.0 hours) compared to wild-type AcNPV (LT50 125 hours). Production of AaIT was confirmed by western blot analysis of larval hemolymph from infected H. virescens, and bioassays with larvae of Sarcophaga falculata.

Insecticidal effects of an insect-specific neurotoxin expressed by a recombinant baculovirus

The scorpion Androctonus australis has a peptide (AaIT) which selectively targets the insect sodium channel. This mode of action is similar to that of many widely used chemical insecticides. When Bombyx mori larvae were infected with a recombinant baculovirus carrying a synthetic AaIT gene, the expressed protein was secreted into the hemolymph and caused symptoms consistent with sodium channel blocking, including tremors and feeding cessation at 40 hr p.i. followed by paralysis and death by 60 hr p.i. Larvae infected with control virus died by 96 hr p.i. These results indicate that foreign genes can be used in recombinant baculoviruses to reduce insect feeding damage and increase the rate of insect kill.

Evaluation of an alginate dressing for pressure ulcers

Pressure ulcers that secrete moderate to large amounts of fluid often cause leakage from under dressings, odor, staining of clothing, denuding of the skin, and pain. Two highly absorbent dressings derived from seaweed have been introduced into the U.S. market for use in the management of exuding wounds. Severely debilitated patients with full-thickness pressure ulcers were treated for one week to three months with one of these alginate dressings (Kaltostat). The handling and performance characteristics of the dressing are discussed.

Functional duality and structural uniqueness of depressant insect-selective neurotoxins

Depressant insect-selective neurotoxins derived from scorpion venoms (a) induce in blowfly larvae a short, transient phase of contraction similar to that induced by excitatory neurotoxins followed by a prolonged flaccid paralysis and (b) displace excitatory toxins from their binding sites on insect neuronal membranes. The present study was undertaken in order to examine the basis of these similarities by comparing the primary structures and neuromuscular effects of depressant and excitatory toxins. A new depressant toxin (LqhIT2) was purified from the venom of the Israeli yellow scorpion. The effects of this toxin on a prepupal housefly neuromuscular preparation mimic the effects on the intact animal; i.e., a brief period of repetitive bursts of junction potentials is followed by suppression of their amplitude and finally by a block of neuromuscular transmission. Loose patch clamp recordings indicate that the repetitive activity has a presynaptic origin in the motor nerve and closely resembles the effect of the excitatory toxin AaIT. The final synaptic block is attributed to neuronal membrane depolarization, which results in an increase in spontaneous transmitter release; this effect is not induced by excitatory toxin. The amino acid sequences of three depressant toxins were determined by automatic Edman degradation. The depressant toxins comprise a well-defined family of polypeptides with a high degree of sequence conservation. This group differs considerably in primary structure from the excitatory toxin, with which it shares identical or related binding sites, and from the two groups of scorpion toxins that affect sodium conductance in mammals. The two opposing pharmacological effects of depressant toxins are discussed in light of the above data.