Expression of nine-banded armadillo (Dasypus novemcinctus) interleukin-2 in E. coli

The nine-banded armadillo (Dasypus novemcinctus) is the only immunologically intact animal that regularly develops lepromatous-type leprosy when inoculated with Mycobacterium leprae. However, the ability to exploit this model for understanding the pathogenesis of leprosy has been limited by a lack of suitable immunological reagents. Recently, efforts began to sequence the entire armadillo genome, and this sequence information will help make possible the development of a wide array of new immunological reagents suitable for use with armadillos. Using the available sequence data, a region of high homology to interleukin-2 of other mammals was identified. Primers were designed to amplify the coding region corresponding to the mature peptide and its exact sequence was confirmed. cDNA was made from ConA-stimulated armadillo PBMC. The amplified coding region was sub-cloned into a pET expression vector and transformed into Escherichia coli for over-expression. The subsequent product was characterized by SDS-PAGE and bioassays. Tritiated thymidine incorporation by CTLL-2 and armadillo lymphoblasts confirmed functionality of the recombinant product. The advent of the D. novemcinctus genome sequence and subsequent generation of immunological tools will assist in advancing the armadillo as a translational model for leprosy.

Efficacy of topical aciclovir for the treatment of feline herpetic keratitis: results of a prospective clinical trial and data from in vitro investigations

This study aimed to evaluate the efficacy of topical ophthalmic aciclovir applied five times daily as a treatment for feline herpesvirus type 1 (FHV-1) keratitis in a group of cats in a first-opinion practice setting. Cats with ocular signs indicative of FHV-1 or Chlamydophila species infection, predominantly conjunctivitis and keratitis, were tested for FHV-1 antigen using an immunofluorescent technique on air-dried conjunctival swabs. They were first treated with topical chlortetracycline with efficacy against Chlamydophila species and then, in cases positive for FHV-1, with topical aciclovir. The time to recovery was determined and illustrated using a Kaplan-Meier plot. Three cats were infected with Chlamydophila species and showed a median time to recovery of 14 days (95 per cent confidence interval [CI] 10 to 18 days), while 30 cats infected with FHV-1 showed a median time to recovery of 12 days (95 per cent CI 10 to 14 days). The drug dose at which 50 per cent plaque reduction (ED50) occurred in a standard plaque reduction assay was determined in an in vitro study. This showed a mean (SD) ED50 of aciclovir of 25 (3.5) mg/ml compared with 0.4 (0.05) mg/ml for trifluorothymidine, a drug known to be efficacious against FHV-1. The study shows that even though aciclovir is generally considered to lack efficacy against ocular FHV-1 infection, when used frequently it can have a beneficial effect in FHV-1 conjunctivitis and keratitis.

Retinal dysplasia in wild otters (Lutra lutra )

Eyes from 88 otters found dead in south-west England between 1990 and 2000, were collected as part of a larger pathological study. Histopathological examination of 131 eyes revealed dysplastic changes such as rosetting and folding in the retinas of 26 of the otters. In the eyes of 42 of the otters there were postmortem and fixation-induced retinal detachment which complicated the differentiation of dysplastic from normal retina, but 11 eyes had folds which probably indicated a dysplastic pathology. The eyes of 18 of the otters had inflammatory or autolytic changes which precluded a definitive evaluation of their dysplastic status. Liver samples from 55 of the otters were analysed for a range of polychlorinated hydrocarbons and for vitamin A. The otters with dysplastic retinas had significantly lower concentrations of vitamin A and higher concentrations of dieldrin than the otters with normal retinas.

Intraocular oxygen tensions in normal and diseased eyes of farmed halibut

We have previously documented ocular abnormalities in farmed halibut and reported that the production of gas-filled posterior segment cysts appears to be central in the pathogenesis of many, if not all of the signs in these eyes. In a number of fish, gas bubbles may be seen in the anterior chamber of the eye, especially after trauma or strenuous exertion associated with handling. A knowledge of the composition of this gas is important in understanding fully the mechanism of gas and cyst production. Here we report investigations into the composition of gas in the globes of normal fish, fish in which intraocular cysts have been documented previously by ultrasonography and fish where post-mortem examination demonstrated both gas- and fluid-filled choroidal cysts. High levels of oxygen were demonstrated in samples of aqueous from all fish but fish with affected eyes had a statistically significantly higher partial pressure of oxygen than did fish with normal eyes.

Prevalence of canine cataract: preliminary results of a cross-sectional study

OBJECTIVE

In this study 2000 dogs were examined ophthalmoscopically to determine presence of cataract.

MATERIALS AND METHODS

The dogs examined were predominantly from veterinary hospital populations but also from the Waltham Center For Pet Nutrition, rehoming charities and breeding kennels. Prevalence of cataract was thus determined for different age groups (year cohorts). The age at which prevalence of cataract was 50% (C50) was determined indirectly from a fitted prevalence curve.

RESULTS

The mean +/- standard deviation of C50 for all dogs in the study was 9.4 +/- 3.3 years. All dogs over 13.5 years were affected by some degree of lens opacity. C50 was determined for animals of different genders and different breeds. For dogs of six breeds sufficient data were available for calculation of breed-specific C50. In these dogs C50 was positively correlated with longevity with a least squares correlation coefficient of 0.74.

CONCLUSION

The study yields novel findings regarding the prevalence and incidence of cataract in the dog and forms the basis for considerable further work on the epidemiology and pathophysiology of age-related cataract in the dog.

Brainstem melanocortin 3/4 receptor stimulation increases uncoupling protein gene expression in brown fat

Central administration of melanocortin 3 and 4 receptor (MC3/4-R) agonists increases energy expenditure, with the hypothalamus commonly held as the primary site of action. It is also clear, however, that MC4-R are expressed in caudal brainstem structures of relevance to the control of energy expenditure. Three experiments investigated whether hindbrain MC-R contribute to the energy expenditure effects of central MC3/4-R agonist treatments; in each, we examined the effect of fourth intracerebroventricular (i.c.v.) administration of a MC3/4-R agonist, MTII (three injections, each separated by 12 h), on uncoupling protein 1 (UCP-1) gene expression in brown adipose tissue (BAT). First, we compared the effects of fourth and third i.c.v. administration of MTII and found that the hindbrain and forebrain treatments were equally effective at elevating UCP-1 mRNA expression in BAT compared with the respective vehicle-treated group results. A second experiment demonstrated that the fourth i.c.v. MTII-induced rise in UCP-1 expression was mediated by sympathetic outflow to BAT by showing that this response was abolished by surgical denervation of BAT. In the third experiment, we showed that chronic decerebrate rats, like their neurologically intact controls, elevated UCP-1 mRNA expression in response to fourth i.c.v. MTII administration. Taken together, the results indicate that: 1) there is an independent caudal brainstem MC3/4-R trigger for a sympathetically stimulated elevation in BAT UCP-1 gene expression, and 2) the MTII-induced rise in UCP-1 expression can be mediated by circuitry intrinsic to the caudal brainstem and spinal cord.

Use of punctal occlusion in the treatment of canine keratoconjunctivitis sicca

Twenty eyes of 10 dogs with keratoconjunctivitis sicca (KCS) were treated by occlusion of the ventral nasolacrimal punctum with a silicone punctal plug in order to increase the volume of the remaining tear lake. Punctal size was measured using a commercially available punctal gauge and the appropriate sized plug was inserted under local anaesthesia. Seven dogs showed an increase in Schirmer tear test I (STT) value. STT values immediately prior to plug placement were 2.3 +/- 1.7 mm/minute. STT values with punctal occlusion were 6.1 +/- 4.1 mm/minute, giving a mean increase of 3.8 +/- 2.7 mm/minute (P<0.001). In 14 eyes of eight dogs, the increase in STT values was accompanied by a clinical improvement in the appearance of the ocular surface. In the three dogs with no increase in STT values, the use of punctal plugs reduced the frequency of artificial tear replacement therapy required to maintain a healthy ocular surface. These results show that use of punctal plugs in dogs with KCS may be appropriate where other lacrimomimetic medications have been unsuccessful.

Clinical pathology accreditation: standards for the medical laboratory

This article describes a new set of revised standards for the medical laboratory, which have been produced by Clinical Pathology Accreditation (UK) Ltd (CPA). The original standards have been in use since 1992 and it was recognised that extensive revision was required. A standards revision group was established by CPA and this group used several international standards as source references, so that the resulting new standards are compatible with the most recent international reference sources. The aim is to make the assessment of medical laboratories as objective as possible in the future. CPA plans to introduce these standards in the UK in 2003 following extensive consultation with professional bodies, piloting in selected laboratories, and training of assessors.

Scavenger receptor class B type I affects cholesterol homeostasis by magnifying cholesterol flux between cells and HDL

Results from several laboratories clearly indicate that expression of scavenger receptor class B type I (SR-BI) enhances the bidirectional flux of cholesterol between cells and lipoproteins. Because the activity of HMG-CoA reductase, the key enzyme in cholesterol biosynthesis, is regulated by cell cholesterol content, we designed experiments to investigate the effect of SR-BI expression on the activity of this enzyme and on net cellular cholesterol mass. In addition, we compared the function of SR-BI with its human homolog, CD36 and LIMPII analogous 1. Our experiments demonstrate that both receptors enhance the flux of unesterified or free cholesterol bidirectionally, down a concentration gradient. Receptor-mediated cholesterol flux can effectively modulate multiple aspects of cellular cholesterol metabolism, including the pool that regulates the activity of HMG-CoA reductase. We also found that constitutive expression of SR-BI alters the steady state level of cellular cholesterol and phospholipid when SR-BI-expressing cells are maintained in medium containing serum lipoproteins. All of these effects are proportional to the level of receptor on the cell surface. These data indicate that the level of SR-BI expression determines both the rate of free cholesterol flux and the steady state level of cellular cholesterol.

Scavenger receptor class B, type I-mediated uptake of various lipids into cells. Influence of the nature of the donor particle interaction with the receptor

Scavenger receptor (SR)-BI is the first molecularly defined receptor for high density lipoprotein (HDL) and it can mediate the selective uptake of cholesteryl ester into cells. To elucidate the molecular mechanisms by which SR-BI facilitates lipid uptake, we examined the connection between lipid donor particle binding and lipid uptake using kidney COS-7 cells transiently transfected with SR-BI. We systematically compared the uptake of [(3)H]cholesteryl oleoyl ether (CE) and [(14)C]sphingomyelin (SM) from apolipoprotein (apo) A-I-containing reconstituted HDL (rHDL) particles and apo-free lipid donor particles. Although both types of lipid donor could bind to SR-BI, only apo-containing lipid donors exhibited preferential delivery of CE over SM (i.e. nonstoichiometric lipid uptake). In contrast, apo-free lipid donor particles (phospholipid unilamellar vesicles, lipid emulsion particles) gave rise to stoichiometric lipid uptake due to interaction with SR-BI. This apparent whole particle uptake was not due to endocytosis, but rather fusion of the lipid components of the lipid donor with the cell plasma membrane; this process is perhaps mediated by a fusogenic motif in the extracellular domain of SR-BI. The interaction of apoA-I with SR-BI not only prevents fusion of the lipid donor with the plasma membrane but also allows the optimal selective lipid uptake. A comparison of rHDL particles containing apoA-I and apoE-3 showed that while both particles bound equally well to SR-BI, the apoA-I particle gave approximately 2-fold greater CE selective uptake. Catabolism of all major HDL lipids can occur via SR-BI with the relative selective uptake rate constants for CE, free cholesterol, triglycerides (triolein), and phosphatidylcholine being 1, 1.6, 0.7, and 0.2, respectively. It follows that a putative nonpolar channel created by SR-BI between the bound HDL particle and the cell plasma membrane is better able to accommodate the uptake of neutral lipids (e.g. cholesterol) relative to polar phospholipids.

Identification and characterization of novel mammalian neuropeptide FF-like peptides that attenuate morphine-induced antinociception

The two mammalian neuropeptides NPFF and NPAF have been shown to have important roles in nociception, anxiety, learning and memory, and cardiovascular reflex. Two receptors (FF1 and FF2) have been molecularly identified for NPFF and NPAF. We have now characterized a novel gene designated NPVF that encodes two neuropeptides highly similar to NPFF. NPVF mRNA was detected specifically in a region between the dorsomedial and ventromedial hypothalamic nuclei. NPVF-derived peptides displayed higher affinity for FF1 than NPFF-derived peptides, but showed poor agonist activity for FF2. Following intracerebral ventricular administration, a NPVF-derived peptide blocked morphine-induced analgesia more potently than NPFF in both acute and inflammatory models of pain. In situ hybridization analysis revealed distinct expression patterns of FF1 and FF2 in the rat central nervous system. FF1 was broadly distributed, with the highest levels found in specific regions of the limbic system and the brainstem where NPVF-producing neurons were shown to project. FF2, in contrast, was mostly expressed in the spinal cord and some regions of the thalamus. These results indicate that the endogenous ligands for FF1 and FF2 are NPVF- and NPFF-derived peptides, respectively, and suggest that the NPVF/FF1 system may be an important part of endogenous anti-opioid mechanism.

Direct NO group transfer from S-nitrosothiols to iron centres

A number of S-nitrosothiols react rapidly with the Fe(II) complexes of 2,3-dimercapto-1-propanesulfonic acid (DMPS) and of N-methyl-D-glucamine dithiocarbamate (MGD), transferring the NO group directly to the iron centres.

A proton nuclear magnetic resonance method for the quantitative analysis on a dry weight basis of (1-->3)-beta-D-glucans in a complex, solvent-wet matrix

Health benefits of the polysaccharide (1-->3)-beta-D-glucan, reported to induce immunobiological, hypocholesterolemic, and hypoglycemic effects in humans and animals, have made the isolation, characterization, and assay of a viable glucan product critical. A new analytical method, based on internal standard proton NMR analysis, for the assay of solvent-wet samples containing (1-->3)-beta-D-glucan is presented. The method enables glucan identification, provides a solvent-free assay, and improves upon the previous multistep extraction and lyophilization procedure by reducing the 1-2 day analysis time to 1-2 h. NMR offers a rapid method for quantifying the glucan in commercial samples, such as nutraceuticals, as well as industrial samples enabling better evaluation of the efficacy of these carbohydrates in health-related applications.

The importance of a beta-glucan receptor in the nonopsonic entry of nontypeable Haemophilus influenzae into human monocytic and epithelial cells

Previous reports showed that nontypeable Haemophilus influenzae (NTHi) reside in macrophage-like cells in human adenoid tissue. This study investigated the ability of nonopsonized NTHi and encapsulated H. influenzae type b (Hib) to enter human monocytic and epithelial cells. The number of intracellular bacteria was determined by a viability assay and flow cytometry. To characterize the mechanisms responsible for the internalization of NTHi, different inhibitors of surface molecules, receptor turnover, and the cytoskeleton were used. Hib were found in monocytic cells at very low numbers (<100 bacteria/2x105 cells). In contrast, a great variation in intracellular numbers was detected between the different NTHi isolates (range, 0.0007%-0.28% of the inoculum for monocytes and 0.053%-3.5% for epithelial cells). NTHi entered human monocytic and epithelial cells via a receptor-mediated endocytosis involving mainly a beta-glucan receptor that could be blocked by laminarin.

Capillary electrophoresis-based heteroduplex analysis with a universal heteroduplex generator for detection of point mutations associated with rifampin resistance in tuberculosis

BACKGROUND

Slab gel heteroduplex analysis (HDA), a popular scanning method for genetic mutations, uses DNA fragments typically generated by PCR to create homo- and heteroduplex molecules with conformational differences and sequence-dependent electrophoretic profiles. Use of a universal heteroduplex generator (UHG) enhances the subtle variations caused by single-base substitutions.

METHODS

The HDA-UHG slab gel format was modified for an efficient capillary-based method. The effect of staining dyes TOPRO5 and YOPRO1 on the analysis of heteroduplexes was studied, as well as ultraviolet absorbance and laser-induced fluorescence (LIF) detection methods. In addition, the entangled polymers hydroxyethyl cellulose, methyl cellulose, and linear polyacrylamide were evaluated as separation matrices.

RESULTS

This assay was able to detect the presence of Mycobacterium tuberculosis and its rifampin susceptibility directly from clinical specimens in dramatically reduced analysis time (30 min vs 2.5 h). Optimized conditions included 0.3% methyl cellulose as the separation matrix, on-line staining using 1 micromol/L YOPRO1, and LIF detection for quantitative and reproducible analysis of single-base substitutions in the rifampin resistance-determining region of rpoB that give rise to the rifampin-resistant phenotype of M. tuberculosis. We generated 95% confidence limits using the wild-type sequence and used these limits to determine rifampin susceptibility in samples.

CONCLUSIONS

Capillary electrophoresis, combined with the HDA-UHG technique, may be of value for rapid and efficient clinical diagnosis of rifampin-resistant tuberculosis strains.

Gemcitabine modulation of alkylator therapy: a phase I trial of escalating gemcitabine added to fixed doses of ifosfamide and doxorubicin

BACKGROUND

The authors investigated the maximum tolerated dose (MTD) and dose limiting toxicity (DLT) associated with the addition of a biomodulating dose of gemcitabine to an established regimen of ifosfamide and doxorubicin as part of a program to explore the potential of low-dose gemcitabine to modulate the activity of alkylating agents.

METHODS

A Phase I trial was carried out in a population of patients with bladder or pelvic carcinoma for whom no standard therapy was available. Doses of ifosfamide and doxorubicin were held fixed at 2 g/m(2) for 4 days and 20 mg/m(2) for 3 days, respectively. Gemcitabine was given on Day 2 and Day 4 at doses of 90 mg/m(2), 150 mg/m(2), and 200 mg/m(2) per dose.

RESULTS

A total of 18 patients received 53 courses of therapy. Myelosuppression was dose limiting. Nonhematologic toxicity also was significant, with 10 of 18 patients experiencing toxicity of Grade 3 or greater. For previously untreated patients with an intact performance status, the MTD for gemcitabine in this context was at least 150 mg/m(2) per dose. According to an intent-to-treat analysis, 11 of 18 patients demonstrated a clinically significant response to this regimen.

CONCLUSIONS

The regimen of ifosfamide and doxorubicin with the addition of gemcitabine was significantly toxic but has promising activity. Based on the observed activity and the generally reversible nature of the toxicity, the authors have initiated a Phase II trial of this regimen in patients with untreated, metastatic urothelial carcinoma.

Normal human fibroblasts express pattern recognition receptors for fungal (1-->3)-beta-D-glucans

Fungal cell wall glucans nonspecifically stimulate various aspects of innate immunity. Glucans are thought to mediate their effects via interaction with membrane receptors on macrophages, neutrophils, and NK cells. There have been no reports of glucan receptors on nonimmune cells. We investigated the binding of a water-soluble glucan in primary cultures of normal human dermal fibroblasts (NHDF). Membranes from NHDF exhibited saturable binding with an apparent dissociation constant (K(D)) of 8.9 +/- 1.9 microg of protein per ml and a maximum binding of 100 +/- 8 resonance units. Competition studies demonstrated the presence of at least two glucan binding sites on NHDF. Glucan phosphate competed for all binding sites, with a K(D) of 5.6 microM (95% confidence interval [CI], 3.0 to 11 microM), while laminarin competed for 69% +/- 6% of binding sites, with a K(D) of 3.7 microM (95% CI, 1.9 to 7.3 microM). Glucan (1 microg/ml) stimulated fibroblast NF-kappaB nuclear binding activity and interleukin 6 (IL-6) gene expression in a time-dependent manner. NF-kappaB was activated at 4, 8, and 12 h, while IL-6 mRNA levels were increased by 48% at 8 h. This is the first report of pattern recognition receptors for glucan on human fibroblasts and the first demonstration of glucan binding sites on cells other than leukocytes. It also provides the first evidence that glucans can directly modulate the functional activity of NHDF. These results provide new insights into the mechanisms by which the host recognizes and responds to fungal (1-->3)-beta-D-glucans and suggests that the response to glucans may not be confined to cells of the immune system.

The apolipoprotein E-dependent low density lipoprotein cholesteryl ester selective uptake pathway in murine adrenocortical cells involves chondroitin sulfate proteoglycans and an alpha 2-macroglobulin receptor

Cells acquire lipoprotein cholesterol by receptor-mediated endocytosis and selective uptake pathways. In the latter case, lipoprotein cholesteryl ester (CE) is transferred to the plasma membrane without endocytosis and degradation of the lipoprotein particle. Previous studies with Y1/E/tet/2/3 murine adrenocortical cells that were engineered to express apolipoprotein (apo) E demonstrated that apoE expression enhances low density lipoprotein (LDL) CE uptake by both selective and endocytic pathways. The present experiments test the hypothesis that apoE-dependent LDL CE selective uptake is mediated by scavenger receptor, class B, type I (SR-BI). Surprisingly, SR-BI expression was not detected in the Y1/E/tet/2/3 clone of Y1 adrenocortical cells, indicating the presence of a distinct apoE-dependent pathway for LDL CE selective uptake. ApoE-dependent LDL CE selective uptake in Y1/E/tet/2/3 cells was inhibited by receptor-associated protein and by activated alpha(2)-macroglobulin (alpha(2)M), suggesting the participation of the LDL receptor-related protein/alpha(2)M receptor. Reagents that inhibited proteoglycan synthesis or removed cell surface chondroitin sulfate proteoglycan completely blocked apoE-dependent LDL CE selective uptake. None of these reagents inhibited SR-BI-mediated LDL CE selective uptake in the Y1-BS1 clone of Y1 cells in which LDL CE selective uptake is mediated by SR-BI. We conclude that LDL CE selective uptake in adrenocortical cells occurs via SR-BI-independent and SR-BI-dependent pathways. The SR-BI-independent pathway is an apoE-dependent process that involves both chondroitin sulfate proteoglycans and an alpha(2)M receptor.

Simultaneous detection of Mycobacterium leprae and its susceptibility to dapsone using DNA heteroduplex analysis

Currently recommended control measures for treating leprosy with multidrug therapy should control the spread of drug-resistant strains; however, dapsone (DDS) resistance continues to be reported. Comprehensive estimates of drug-resistant leprosy are difficult to obtain due to the cumbersome nature of the conventional drug susceptibility testing method using mouse footpad inoculation, which requires at least 6 months to obtain results. Recently, it has been determined that DDS-resistant strains contain missense mutations in codon 53 or 55 of the folP1 gene of Mycobacterium leprae, and definitive evidence linking these mutations with DDS resistance in M. leprae has been obtained. Based on these mutations, a heteroduplex DDS M. leprae (HD-DDS-ML) assay was developed for the simultaneous detection of M. leprae and of its susceptibility to DDS. The assay relies on the PCR amplification of an M. leprae-specific 231-bp fragment of folP1 containing codons 53 and 55. The PCR products are allowed to anneal to a universal heteroduplex generator, and the separation of the resultant DNA duplexes is accomplished by polyacrylamide gel electrophoresis. M. leprae was detected in crude cell lysates of skin biopsy specimen homogenates from eight leprosy patients and from M. leprae-infected mouse or armadillo tissues infected with 14 separate strains using the HD-DDS-ML assay. The assay was specific for M. leprae in a comparison with results obtained from 14 species of mycobacteria other than M. leprae and four bacterial species known to colonize human skin. The HD-DDS-ML assay detected as few as 100 M. leprae organisms present in homogenates of human skin and demonstrated a 93% correlation with DDS susceptibility as determined by both DNA sequencing of folP1 and mouse footpad susceptibility testing. The HD-DDS-ML assay provides a new tool for the simultaneous detection of M. leprae and of its susceptibility to DDS from a single specimen. The assay should prove useful for drug resistance surveillance in leprosy control programs when combined with similar molecular tests developed for other drug resistance markers.

Biochemical analysis of cell-derived apoE3 particles active in stimulating neurite outgrowth

Susceptibility to the development of late-onset Alzheimer's disease is increased for individuals harboring one or more apolipoprotein E4 (apoE4) alleles. Although several isoform-specific effects of apoE have been identified, the relationship between biochemical function and risk factor assessment is unknown. Our previous studies showed that a physiologically relevant cell-derived apoE3 particle stimulates neurite outgrowth in an isoform-specific manner. In an attempt to delineate the biochemical mechanism responsible for the stimulatory effects of apoE3 on neurite outgrowth, we performed a detailed physical characterization of cell-derived apoE3 and apoE4 particles. Immunoaffinity chromatography followed by SDS-PAGE illustrated homogeneity in protein content (apoE >95%). The affinity-purified particles contained phospholipid and 1 mol of cholesterol per mole of apoE but no core lipids. Nondenaturing gradient gel electrophoresis identified two major particle populations with hydrated diameters of 8.0 and 9.2 nm. Neurite outgrowth assays performed with the affinity-purified particles resulted in similar isoform-specific differences as seen previously, apoE3 stimulatory and apoE4 neutral. Interestingly, we did not observe a reduction in apoE medium concentrations over the duration of the neurite outgrowth assays, suggesting little or no endocytic uptake. Ligand blot analysis demonstrated that the affinity-purified apoE particles bind to several Neuro-2a membrane proteins. Western blots of the Neuro-2a membrane proteins indicated that the LDL receptor, gp330, and LR8B might be involved in the apoE-binding event. These results discriminate against the lipid delivery hypothesis and suggest that the biological activity of the phospholipid apoE3 particles may be due to cell surface signaling.

Analysis of chimeric receptors shows that multiple distinct functional activities of scavenger receptor, class B, type I (SR-BI), are localized to the extracellular receptor domain

Scavenger receptor BI (SR-BI) mediates the selective uptake of high-density lipoprotein (HDL) cholesteryl ester (CE), a process by which HDL CE is taken into the cell without degradation of the HDL particle. In addition, SR-BI stimulates the bi-directional flux of free cholesterol (FC) between cells and lipoproteins, an activity that may be responsible for net cholesterol efflux from peripheral cells as well as the rapid hepatic clearance of FC from plasma HDL. SR-BI also increases cellular cholesterol mass and alters cholesterol distribution in plasma membrane domains as judged by the enhanced sensitivity of membrane cholesterol to extracellular cholesterol oxidase. In contrast, CD36, a closely related class B scavenger receptor, has none of these activities despite binding HDL with high affinity. In the present study, analyses of chimeric SR-BI/CD36 receptors and domain-deleted SR-BI have been used to test the various domains of SR-BI for functional activities related to HDL CE selective uptake, bi-directional FC flux, and the alteration of membrane cholesterol mass and distribution. The results show that each of these activities localizes to the extracellular domain of SR-BI. The N-terminal cytoplasmic tail and transmembrane domains appear to play no role in these activities other than targeting the receptor to the plasma membrane. The C-terminal tail of SR-BI is dispensable for activity as well for targeting to the plasma membrane. Thus, multiple distinct functional activities are localized to the SR-BI extracellular domain.

Implementation of current Louisiana mammography legislation: a time for review

Breast cancer mortality rates in the state of Louisiana are higher than national averages despite a lower than average incidence rate. Given the importance of early diagnosis in determining breast cancer outcomes, one potential explanation for relatively high mortality rates is an under-utilization of effective techniques for early detection. Comparison of mammography rates in Medicare recipients indicates that Louisiana mammography rates are among the lowest in the nation. To better assess barriers to mammography utilization, all certified mammography sites in Louisiana were contacted by telephone by a surveyor posing as a family member attempting to schedule a mammogram for a 50-year-old woman. Of the 151 sites in Louisiana, successful scheduling of a mammogram by phone was accomplished nine times. The vast majority of sites (94%) did not schedule a mammogram. Furthermore, 75.9% of the sites contacted provided no assistance to the consumer seeking a mammogram. Current Louisiana law requires that mammography be ordered by a licensed health care provider. Though compliance with current law is high, this law may provide a barrier to interested consumers attempting to schedule mammography. A revision of current law and policy may be indicated in an effort to increase mammography utilization rates. Such an effort may potentially help to decrease mortality from the second leading cause of cancer death in women.

Early activation of IKKbeta during in vivo myocardial ischemia

We have demonstrated that in vitro brief ischemia activates nuclear factor (NF)-kappaB in rat myocardium. We report in vivo ischemia-reperfusion (I/R)-induced NF-kappaB activation, IkappaB kinase -beta (IKKbeta) activity, and IkappaBalpha phosphorylation and degradation in rat myocardium. Rat hearts were subjected to occlusion of the coronary artery for up to 45 min or occlusion for 15 min followed by reperfusion for up to 3 h. Cytoplasmic and nuclear proteins were isolated from ischemic and nonischemic areas of each heart. NF-kappaB activation was increased in the ischemic area (680%) after 10 min of ischemia and in the nonischemic area (350%) after 15 min of ischemia and remained elevated during prolonged ischemia and reperfusion. IKKbeta activity was markedly increased in ischemic (1,800%) and nonischemic (860%) areas, and phosphorylated IkappaBalpha levels were significantly elevated in ischemic (180%) and nonischemic (280%) areas at 5 min of ischemia and further increased after reperfusion. IkappaBalpha levels were decreased in the ischemic (45%) and nonischemic (36%) areas after 10 min of ischemia and remained low in the ischemic area during prolonged ischemia and reperfusion. The results suggest that in vivo I/R rapidly induces IKKbeta activity and increases IkappaBalpha phosphorylation and degradation, resulting in NF-kappaB activation in the myocardium.

Glucans exhibit weak antioxidant activity, but stimulate macrophage free radical activity

Polymeric carbohydrates have been reported to modulate inflammatory responses in vitro and in vivo. Previous reports suggest that certain carbohydrate polymers, such as (1-->3)-beta-D-glucans, may possess free radical scavenging activity. If glucans are free radical scavengers then it might explain, in part, the ability of these ligands to modulate inflammatory responses. The present study examined the free radical scavenging activity of a variety of carbohydrate polymers and the effect of the polymers on free radical levels in a murine macrophage cell line. All of the carbohydrates exhibited concentration dependent antioxidant effects (EC(50) range = 807 to 43 microg/ml). However, the antioxidant activity for the carbohydrates was modest in comparison with PDTC (EC(50) = 0.13 microg/ml) and the carbohydrate concentration required for antioxidant activity was high (x EC(50) = 283 microg/ml). The antioxidant ability of the polymers was greater (p < .05) than their monosaccharide constituents, i.e., dextrose EC(50) = 807 vs. glucan sulfate EC(50) = 43 microg/ml. Coincubation of glucans with murine J774a.1 cells increased free radical levels when compared to controls. Therefore, the weak free radical scavenging activity of glucan polymers cannot explain their modulatory effect on inflammatory responses in tissue culture and/or disease models of inflammation.

Detection of anthropogenic radionuclides by the CA002 monitoring station for the comprehensive test ban treaty

A worldwide monitoring system for radioactive aerosols is being implemented for verification of the Comprehensive Test Ban Treaty. These 80 stations will detect airborne radioactivity not only from nuclear explosions but also from other anthropogenic and natural sources. A prototype unit has been in operation since April 1996 in Vancouver, British Columbia, Canada. It is a very sensitive system and reports clear signals for natural radioactivity, including cosmogenic 7Be, and the decay products from soil exhalation of 220Rn (thoron). In addition, there have been frequent detections of anthropogenic nuclides, probably coming from three distinct facilities-a medical isotope production center, a major university hospital, and a particle accelerator laboratory--all between 1 and 2 km away from the monitoring station. This experience is discussed to sensitize health physicists to the potential uses of this publicly available information.

Schistosome infection stimulates host CD4(+) T helper cell and B-cell responses against a novel egg antigen, thioredoxin peroxidase

Egg granuloma formation during schistosome infections is mediated by CD4(+) T helper (Th) cells sensitized to egg antigens; however, most of the relevant sensitizing egg antigens are still unknown. Here we show that schistosome thioredoxin peroxidase (TPx)-1 is a novel T- and B-cell egg antigen in schistosome-infected mice. CD4(+) Th cell responses to fractionated egg components identified a significant response against a 26-kDa antigen; a partial amino acid sequence of this antigen was found to be identical to that of Schistosoma mansoni TPx-1. The native TPx-1 elicited significant proliferative responses as well as gamma interferon (IFN-gamma), interleukin-2 (IL-2), IL-4, and IL-5 secretion in CD4(+) cells from 8.5-week-infected CBA and C57BL/6 mice. By comparison, recombinant TPx-1 elicited a smaller, more type 1-polarized response, with significant production of IFN-gamma and IL-2, less IL-5, and essentially no IL-4. In C57BL/6 mice the responses to TPx-1 were relatively more prominent than that directed against the major egg antigen, Sm-p40, whereas in CBA mice the reverse was true. B-cell responses were also monitored in infected C57BL/6, C3H, CBA, and BALB/c mice. All strains had significant antibody levels against the TPx-1 protein, but the most significant antibody production ensued following parasite oviposition. TPx-1 was localized in eggs and shown to be secreted by eggs. The identification of egg antigens is important to understand the specific basis of granuloma formation in schistosome infections and may prove to be useful in strategies to ameliorate pathological responses.

Chiari type I malformation and postoperative respiratory failure

PURPOSE

To present a case of respiratory failure following suboccipital craniectomy for Chiari type I malformation.

CLINICAL FEATURES

A 22-yr-old man presented with a two year history of symptoms and signs suggestive of brainstem compression at the level of the foramen magnum. This was confirmed with magnetic resonance imaging. The procedure of suboccipital craniectomy, upper cervical laminectomy and fourth ventricle exploration was performed. Three hours postoperatively the patient experienced episodes of apnea and subsequently became drowsy. Blood gas analysis revealed hypercapnic respiratory failure. Chest X-ray revealed evidence of pulmonary aspiration. The trachea was re-intubated and the lungs ventilated in intensive care for 72 hr. He was discharged home two weeks postoperatively.

CONCLUSION

Chiari type I malformation is associated with a number of associated anomalies. These patients are at considerable risk of respiratory depression and bulbar dysfunction in the perioperative period. The anesthetic issues are reviewed and discussed.

Dapsone resistance in Mycobacterium leprae

The folP1 gene of Mycobacterium leprae, which encodes dihydropteroate synthase (DHPS), was studied for the presence of mutations associated with resistance to dapsone (DDS). When the folP1 of several DDS-resistant clinical isolates of M. leprae were sequenced, two missense mutations were identified. One mutation occurred at codon 53, substituting isoleucine for threonine in DHPS-1, and a second mutation occurred in codon 55, substituting arginine for proline. DNA sequencing of strains of M. leprae resistant to 0.01 g% DDS in the mouse diet revealed that 13 of 14 strains contained either the 53 or 55 folP1 mutation. None of the susceptible strains and only one of five strains resistant to 0.001 g% DDS revealed a mutation in folP1, suggesting that only high-level DDS resistance is associated with the mutations identified in folP1. Development and application of simple molecular tests to assess drug-related mutations in M. leprae could establish current levels of drug resistance in leprosy as a reference point for future monitoring of drug resistance at the global level.

High density lipoprotein phospholipid composition is a major determinant of the bi-directional flux and net movement of cellular free cholesterol mediated by scavenger receptor BI

The role of high density lipoprotein (HDL) phospholipid in scavenger receptor BI (SR-BI)-mediated free cholesterol flux was examined by manipulating HDL(3) phosphatidylcholine and sphingomyelin content. Both phosphatidylcholine and sphingomyelin enrichment of HDL enhanced the net efflux of cholesterol from SR-BI-expressing COS-7 cells but by two different mechanisms. Phosphatidylcholine enrichment of HDL increased efflux, whereas sphingomyelin enrichment decreased influx of HDL cholesterol. Although similar trends were observed in control (vector-transfected) COS-7 cells, SR-BI overexpression amplified the effects of phosphatidylcholine and sphingomyelin enrichment of HDL 25- and 2.8-fold, respectively. By using both phosphatidylcholine-enriched and phospholipase A(2)-treated HDL to obtain HDL with a graded phosphatidylcholine content, we showed that SR-BI-mediated cholesterol efflux was highly correlated (r(2) = 0.985) with HDL phosphatidylcholine content. The effects of varying HDL phospholipid composition on SR-BI-mediated free cholesterol flux were not correlated with changes in either the K(d) or B(max) values for high affinity binding to SR-BI. We conclude that SR-BI-mediated free cholesterol flux is highly sensitive to HDL phospholipid composition. Thus, factors that regulate cellular SR-BI expression and the local modification of HDL phospholipid composition will have a large impact on reverse cholesterol transport.

Roles of scavenger receptor BI and APO A-I in selective uptake of HDL cholesterol by adrenal cells

Adrenal cells obtain cholesterol for steroid production via the selective uptake of cholesteryl ester (CE) from HDL particles, a process in which CE is transferred to the plasma membrane without degradation of the HDL particle. Although this process has been studied for two decades, only recently have the receptor and the HDL ligand been identified. Scavenger class B, type I, (SR-BI) is regulated by ACTH in adrenocortical cells in parallel with steroid production. Antibody to SR-BI blocks the uptake and utilization of HDL CE for steroid production in Y1-BS1 adrenal cells. The adrenal glands of SR-BI knockout mice are depleted in cholesterol providing complementary evidence that SR-BI is responsible for HDL CE accumulation in adrenal cells. SR-BI-mediated HDL CE selective uptake is a two-step process in which SR-BI first interacts with multiple sites in apoA-I with the amphipathic inverted alpha-helical repeat units of apoA-I serving as recognition motifs. This is followed by efficient CE transfer down its concentration gradient to the plasma membrane, a process requiring the extracellular domain of SR-BI. Other scavenger receptors bind HDL but do not afford the CE transfer step. Adrenal glands from apoA-I knockout mice lack CE stores, indicating that apoAI is essential for HDL selective uptake in vivo. ApoA-I knockout HDL particles bind normally to SR-BI but do not permit efficient CE transfer to the cell. These findings suggest that apoA-I has an important role in the transfer of HDL CE that goes beyond its function as a ligand for interaction with SR-BI.

Molecular and enzymatic characterization of Schistosoma mansoni thioredoxin peroxidase

The ability of Schistosoma mansoni to escape oxidative damage from immune system-generated reactive oxygen intermediates has been extensively documented. The limiting step in the parasite's detoxification process appears to be at the level of hydrogen peroxide neutralization. In the present study, the possible role of a novel class of antioxidant enzymes, thioredoxin peroxidase (TPx), in hydrogen peroxide neutralization by schistosomes was investigated. An expressed sequence tag was characterized from the Schistosoma Genome Initiative with high similarity to TPx from other organisms. The gene encodes a polypeptide containing 2 conserved active-site cysteines and flanking amino acids, and 60-70% identity with previously characterized TPx proteins. Recombinant schistosome TPx was enzymatically active and found to have thioredoxin-dependent hydrogen peroxide reducing activity of 4500 nmol hydrogen peroxide/min/mg protein. Native TPx activity was determined to be 48.1 nmol hydrogen peroxide/min/mg protein in adult worm homogenates compared with 46.9 for glutathione peroxidase. TPx activity was precipitated from adult worm homogenates with antibodies prepared against the recombinant protein. Western blotting with antibodies made against recombinant protein showed that TPx was expressed in both male and female adult worms. This is the first demonstration of a TPx activity in schistosomes and our results suggest that TPx plays a significant role in schistosome-host interactions.

Intracerebral hemorrhage and Moyamoya disease in pregnancy

PURPOSE

To present a case of Moyamoya disease with intracranial hemorrhage complicating pregnancy.

CLINICAL FEATURES

A 36-yr-old parturient at 34 wk gestation presented with left hemiparesis, headache, nausea and vomiting. Subsequent deterioration in level of consciousness and the development of a dilated right pupil necessitated immediate intubation. Urgent non-contrast CT scan revealed a large right intracerebral hematoma with transtentorial herniation. The patient underwent simultaneous emergency Cesarean section and craniotomy. A postoperative angiogram revealed findings consistent with Moyamoya disease. The neonate survived but the patient developed severe cerebral edema and died eleven days postoperatively.

CONCLUSION

Adult patients with Moyamoya disease often present with intracranial hemorrhage which poses unique anesthetic challenges. We report a case of intracerebral hemorrhage during pregnancy, which is known to be associated with high morbidity and mortality. The anesthetic techniques are reviewed and discussed.

Characterization of the human cysteinyl leukotriene 2 receptor

The contractile and inflammatory actions of the cysteinyl leukotrienes (CysLTs), LTC(4), LTD(4), and LTE(4), are thought to be mediated through at least two distinct but related CysLT G protein-coupled receptors. The human CysLT(1) receptor has been recently cloned and characterized. We describe here the cloning and characterization of the second cysteinyl leukotriene receptor, CysLT(2), a 346-amino acid protein with 38% amino acid identity to the CysLT(1) receptor. The recombinant human CysLT(2) receptor was expressed in Xenopus oocytes and HEK293T cells and shown to couple to elevation of intracellular calcium when activated by LTC(4), LTD(4), or LTE(4). Analyses of radiolabeled LTD(4) binding to the recombinant CysLT(2) receptor demonstrated high affinity binding and a rank order of potency for competition of LTC(4) = LTD(4) LTE(4). In contrast to the dual CysLT(1)/CysLT(2) antagonist, BAY u9773, the CysLT(1) receptor-selective antagonists MK-571, montelukast (Singulair(TM)), zafirlukast (Accolate(TM)), and pranlukast (Onon(TM)) exhibited low potency in competition for LTD(4) binding and as antagonists of CysLT(2) receptor signaling. CysLT(2) receptor mRNA was detected in lung macrophages and airway smooth muscle, cardiac Purkinje cells, adrenal medulla cells, peripheral blood leukocytes, and brain, and the receptor gene was mapped to chromosome 13q14, a region linked to atopic asthma.

Structural characterization of beta-D-(1 --> 3, 1 --> 6)-linked glucans using NMR spectroscopy

Nondestructive structural analysis of a series of beta-D-(1 --> 3, 1 --> 6)-linked glucans (laminaran, curdlan, yeast glucan, scleroglucan, etc.) was performed using two-dimensional NMR spectroscopy. The relative ratios of H-1 at different AGUs provided the information about DPn and DB. The alpha-, and beta-anomeric protons on reducing terminals were assigned at 5.02 to approximately 5.03 ppm (J 3.6 to approximately 3.7 Hz), and 4.42 to approximately 4.43 ppm (J 7.6 to approximately 7.9 Hz), respectively, whereas the H-1 protons of internal AGUs and beta-(1 --> 6)-branched AGUs appeared at 4.56 to approximately 4.59 ppm (J 7.6 to approximately 7.8 Hz), and 4.26 to approximately 4.28 ppm (J 7.6 to approximately 10.6 Hz), respectively, in a mixed solvent of 6:1 Me2SO-d6-D2O at 80 degrees C. In the solvent, the OH peaks were eliminated from the spectra allowing the H-1 protons to appear clearly. In addition, the nonreducing terminal H-1 and H-1 at the AGU next to reducing terminal could be assigned at 4.45 to approximately 4.46 ppm (J 7.8 to approximately 7.9 Hz), and 4.51 to approximately 4.53 ppm (J 7.8 Hz), respectively. The DPn of the laminaran was 33 (polydispersity 1.12) and the DB was 0.07. The number of glucosyl units in the side chain of laminaran is more than one. The DPn and DB of the water-insoluble yeast glucan were 228 and 0.003, respectively. However the DPn of water soluble yeast glucan phosphate and curdlan was changed upon the number of freeze-drying processes and the content of water in the mixed solvent, respectively. And the DB of those were calculated as 0.02 and 0, respectively. The DB of scleroglucan was precisely calculated as 0.33, compared with the previously reported data. The H-1s at different AGUs of the various beta-D-(1 --> 3, 1 --> 6)-linked glucans having different DB can be exactly assigned by their chemical shifts in the mixed solvent system. This NMR analysis can be effectively used to determine the DP and DB of polysaccharides in a simple and non-destructive manner.

Lack of association between lipaemia and central adiposity in subjects with an atherogenic lipoprotein phenotype (ALP)

OBJECTIVE

To investigate the associations between indices of adiposity and cardiovascular risk factors in individuals with an atherogenic lipoprotein phenotype (ALP).

SUBJECTS

Fifty-five men, aged 34-69 y, body mass index (BMI) 22-35 kg/m2, with an ALP lipid profile (triglycerides (TG) 1.5-4.0 mmol/l, HDL<1.1 mmol/l; %LDL-3>40% total LDL).

DESIGN

Each participant provided a fasting blood sample and underwent an 8 h postprandial assessment and had anthropometric measurements taken.

OUTCOME MEASURES

BMI, waist circumference (W), waist-to-hip ratio (W/H), sum of skinfolds (SSK), fasting and postprandial concentrations of glucose, insulin and plasma lipids, post-heparin lipase activity, and apoE genotype.

RESULTS

The expected positive associations between BMI, W and SSK and fasting and postprandial insulin were observed (r=0.42-0.65). Little association between glucose responses and any measures of adiposity was evident. Unexpectedly, there were no positive associations between measures of central adiposity (W and W/H) and fasting and postprandial TG responses, with a trend towards negative associations in this study group (TG AUC vs W, r=-0.23, P=0.097; TG IAUC vs W/H, r=-0.26, P=0.068). Subgroup analysis indicated that lack of a positive association between central adiposity and postprandial TG values was more evident in those with one E4 allele (r=-0.42, P=0.077) relative to non-E4 carriers (r=-0.16, P=0.430). The expected positive associations between insulin and TG responses were not observed (r=-0.03 to -0.36).

CONCLUSION

In this ALP group the expected positive association between TG responses and a centralized distribution of body fat was not observed, particularly in individuals with an apoE4 genotype. Our findings are not in line with the view that there is a clear causal relationship between insulin resistance and the lipid abnormalities associated with ALP.

Structure-reactivity studies of the Cu(2+)-catalyzed decomposition of four S-nitrosothiols based around the S-Nitrosocysteine/S-nitrosoglutathione structures

S-Nitrosoglutathione (GSNO) and the dipeptide derivative S-nitrosoglutamylcysteine (SNO-GluCys) both at 1 x 10(-3) M in pH 7. 4 buffer containing added Cu(2+) (1 x 10(-5) M) are very unreactive toward decomposition (measured spectrophotometrically), and in both cases reaction stops at very low conversion. S-Nitrosocysteine (SNC) and the dipeptide derivative S-nitrosocysteinylglycine (SNO-CysGly), on the other hand, are orders of magnitude more reactive under the same conditions, and reaction proceeds to completion. Initially, we interpreted these results in terms of the requirement of a suitably positioned free NH(2) group (which is available in both SNC and SNO-CysGly, but not in GSNO and SNO-GluCys) for efficient complexation of Cu(+), the effective reagent. However, later results measured at much lower substrate concentration (1 x 10(-6) M) using the NO electrode system showed that at this concentration, all four S-nitrosothiols react at approximately the same rate and yield NO quantitatively. For GSNO the rate and percentage conversion were shown to drop progressively as the substrate concentration increases. All reactions are effectively halted in the presence of the metal ion chelator EDTA. The results can readily be explained in terms of complexation of Cu(2+) by the product disulfides from GSNO (i.e., GSSG) and SNO-GluCys, involving the glutamate residue, which is not present in SNC and SNO-CysGly. This is confirmed by the observed progressive reduction in yield and percentage conversion of GSNO decomposition as GSSG is added, at micromolar substrate concentrations.

Low levels of extrahepatic nonmacrophage ApoE inhibit atherosclerosis without correcting hypercholesterolemia in ApoE-deficient mice

The prevention of atherosclerosis by apolipoprotein E (apoE) is generally attributed to the removal of plasma lipoprotein remnant particles. We developed transgenic apoE-knockout mice expressing apoE specifically in the adrenal gland and found that only 3% of the wild-type plasma level of apoE was sufficient to normalize plasma cholesterol levels in the apoE-deficient mouse. As expected, mice expressing apoE at levels that correct hypercholesterolemia had almost no cholesteryl ester deposition in their aortas. In contrast, their nontransgenic siblings had significant atherosclerosis. Unexpectedly, we found that atherosclerosis was also reduced in 2 transgenic lines expressing too little apoE (<1% to 2% of wild type) to correct their hypercholesterolemia. Gel exclusion chromatographic profiles of plasma lipoproteins and the size distributions of lipoproteins with density <1.063 (low density and very low density lipoproteins), as determined by dynamic laser light scattering, were the same in mice expressing <2 microg/mL plasma apoE and their nontransgenic littermates. We conclude that the antiatherogenic action of low levels of plasma apoE is not due to the clearance of remnant lipoproteins. Thus, low levels of apoE provided systemically, but not made in the liver or in macrophages, can block atherogenesis in the vascular wall independently of normalizing the plasma concentration of atherogenic remnant lipoprotein particles.

Identification of receptors for neuromedin U and its role in feeding

Neuromedin U (NMU) is a neuropeptide with potent activity on smooth muscle which was isolated first from porcine spinal cord and later from other species. It is widely distributed in the gut and central nervous system. Peripheral activities of NMU include stimulation of smooth muscle, increase of blood pressure, alteration of ion transport in the gut, control of local blood flow and regulation of adrenocortical function. An NMU receptor has not been molecularly identified. Here we show that the previously described orphan G-protein-coupled receptor FM-3 (ref. 15) and a newly discovered one (FM-4) are cognate receptors for NMU. FM-3, designated NMU1R, is abundantly expressed in peripheral tissues whereas FM-4, designated NMU2R, is expressed in specific regions of the brain. NMU is expressed in the ventromedial hypothalamus in the rat brain, and its level is significantly reduced following fasting. Intracerebroventricular administration of NMU markedly suppresses food intake in rats. These findings provide a molecular basis for the biochemical activities of NMU and may indicate that NMU is involved in the central control of feeding.

A veterinary approach to the European honey bee (Apis mellifera)

The European honey bee (Apis mellifera) has the unusual status of being an inherently wild species from which a natural foodstuff (honey) is derived by manipulating its behaviour to deposit this in man-made wooden frames. Bees also produce propolis and Royal Jelly which can be harvested but their most important effect is one not immediately obvious as an economic product: that of pollination. Bee diseases are predominantly infectious and parasitic conditions accentuated by the close confinement in which they congregate, either in man-made hives or in colonies in a natural cavity. Treatment or at least control of some of these conditions can be attempted. In some cases natural bee behavioural traits limit the effect of the disease while in others, such as the notifiable disease American foulbrood, destruction of the colony is the only method of control. The mite Varroa jacobsoni can be controlled by the synthetic pyrethroids flumethrin and tau-fluvalinate. The introduction of these products has heightened veterinary interest in this important invertebrate species.

Binding and cross-linking studies show that scavenger receptor BI interacts with multiple sites in apolipoprotein A-I and identify the class A amphipathic alpha-helix as a recognition motif

Scavenger receptor, class B, type I (SR-BI) mediates the selective uptake of high density lipoprotein (HDL) cholesteryl ester without the uptake and degradation of the particle. In transfected cells SR-BI recognizes HDL, low density lipoprotein (LDL) and modified LDL, protein-free lipid vesicles containing anionic phospholipids, and recombinant lipoproteins containing apolipoprotein (apo) A-I, apoA-II, apoE, or apoCIII. The molecular basis for the recognition of such diverse ligands by SR-BI is unknown. We have used direct binding analysis and chemical cross-linking to examine the interaction of murine (m) SR-BI with apoA-I, the major protein of HDL. The results show that apoA-I in apoA-I/palmitoyl-oleoylphosphatidylcholine discs, HDL(3), or in a lipid-free state binds to mSR-BI with high affinity (K(d) congruent with 5-8 microgram/ml). ApoA-I in each of these forms was efficiently cross-linked to cell surface mSR-BI, indicating that direct protein-protein contacts are the predominant feature that drives the interaction between HDL and mSR-BI. When complexed with dimyristoylphosphatidylcholine, the N-terminal and C-terminal CNBr fragments of apoA-I each bound to SR-BI in a saturable, high affinity manner, and each cross-linked efficiently to mSR-BI. Thus, mSR-BI recognizes multiple sites in apoA-I. A model class A amphipathic alpha-helix, 37pA, also showed high affinity binding and cross-linking to mSR-BI. These studies identify the amphipathic alpha-helix as a recognition motif for SR-BI and lead to the hypothesis that mSR-BI interacts with HDL via the amphipathic alpha-helical repeat units of apoA-I. This hypothesis explains the interaction of SR-BI with a wide variety of apolipoproteins via a specific secondary structure, the class A amphipathic alpha-helix, that is a common structural motif in the apolipoproteins of HDL, as well as LDL.

Induced nitric oxide inhibits IL-6-induced stat3 activation and type II acute phase mRNA expression

Inducible nitric oxide synthase (iNOS) can be coexpressed with acute phase reactants in hepatocytes; however, it is unknown if NO can regulate the acute phase response. We tested the hypothesis that iNOS-derived nitric oxide (NO) attenuates the acute phase response by inhibiting IL-6-enhanced Stat3 DNA-binding activity and type II acute phase mRNA expression. iNOS was overexpressed in cultured rat hepatocytes via transduction with a replication defective adenovirus containing cDNA for human iNOS (AdiNOS), and Stat3 DNA-binding activity was determined by electrophoretic mobility shift assay (EMSA). EMSAs demonstrated that AdiNOS inhibits IL-6-induced Stat3 activation and that this inhibition is reversible in the presence of the NOS inhibitor N(G)-monomethyl-L-arginine (L-NMA). The induction of beta-fibrinogen mRNA by IL-6, a Stat3 dependent process, is attenuated in AdiNOS-transduced cells and partially reversed by L-NMA. Thus, iNOS overexpression suppresses IL-6-induced Stat3 activation and type II acute phase mRNA expression in cultured hepatocytes. This suppression may represent a mechanism by which NO down-regulates the acute phase response.

Dihydropteroate synthase of Mycobacterium leprae and dapsone resistance

Two Mycobacterium leprae genes, folP1 and folP2, encoding putative dihydropteroate synthases (DHPS), were studied for enzymatic activity and for the presence of mutations associated with dapsone resistance. Each gene was cloned and expressed in a folP knockout mutant of Escherichia coli (C600DeltafolP::Km(r)). Expression of M. leprae folP1 in C600DeltafolP::Km(r) conferred growth on a folate-deficient medium, and bacterial lysates exhibited DHPS activity. This recombinant displayed a 256-fold-greater sensitivity to dapsone (measured by the MIC) than wild-type E. coli C600, and 50-fold less dapsone was required to block (expressed as the 50% inhibitory concentration [IC(50)]) the DHPS activity of this recombinant. When the folP1 genes of several dapsone-resistant M. leprae clinical isolates were sequenced, two missense mutations were identified. One mutation occurred at codon 53, substituting an isoleucine for a threonine residue (T53I) in the DHPS-1, and a second mutation occurred in codon 55, substituting an arginine for a proline residue (P55R). Transformation of the C600DeltafolP::Km(r) knockout with plasmids carrying either the T53I or the P55R mutant allele did not substantially alter the DHPS activity compared to levels produced by recombinants containing wild-type M. leprae folP1. However, both mutations increased dapsone resistance, with P55R having the greatest affect on dapsone resistance by increasing the MIC 64-fold and the IC(50) 68-fold. These results prove that the folP1 of M. leprae encodes a functional DHPS and that mutations within this gene are associated with the development of dapsone resistance in clinical isolates of M. leprae. Transformants created with M. leprae folP2 did not confer growth on the C600DeltafolP::Km(r) knockout strain, and DNA sequences of folP2 from dapsone-susceptible and -resistant M. leprae strains were identical, indicating that this gene does not encode a functional DHPS and is not involved in dapsone resistance in M. leprae.