Adipokine hormones and hand osteoarthritis: radiographic severity and pain.

INTRODUCTION: Obesity's association with hand osteoarthritis cannot be fully explained by mechanical loading. We examined the relationship between adipokines and radiographic hand osteoarthritis severity and pain. METHODS: In a pilot study of 44 hand osteoarthritis patients (39 women and 5 men), serum adipokine concentrations and hand x-ray Kallman-scores were analyzed using linear regression models. Secondary analyses examined correlates of hand pain. RESULTS: The cohort had a mean age of 63.5 years for women and 72.6 for men; mean (standard deviation) Kallman-scores were 43.3(17.4) for women and 46.2(10.8) for men. Mean body-mass-index was 30 kg/m(2) for women and men. Mean leptin concentration was 32.2 ng/ml (women) and 18.5 ng/ml (men); mean adiponectin-total was 7.9 ng/ml (women) and 5.3 ng/ml (men); mean resistin was 7.3 ng/ml (women) and 9.4 ng/ml (men). No association was found between Kallman-scores and adipokine concentrations (R(2) = 0.00-0.04 unadjusted analysis, all p-values>0.22). Secondary analyses showed mean visual-analog-scale pain of 4.8(2.4) for women and 6.6(0.9) for men. Leptin, BMI, and history of coronary artery disease were found to be associated with visual-analog-scale scores for chronic hand pain (R(2) = 0.36 unadjusted analysis, p-values≤0.04). CONCLUSION: In this pilot study, we found that adipokine serum concentrations were not associated with hand osteoarthritis radiographic severity; the most important correlates of joint damage were age and disease duration. Leptin serum concentration, BMI, and coronary artery disease were associated with the intensity of chronic hand OA pain.

Adipokinetic hormone (Pyrap-AKH) enhances the effect of a pyrethroid insecticide against the firebug Pyrrhocoris apterus.

BACKGROUND: Adipokinetic hormones (AKHs) are insect neuropetides controlling stress situations including those elicited by insecticide treatment. The effect of Pyrap-AKH on the mortality of the firebug Pyrrhocoris apterus (L.) treated with the insecticide permethrin (Ambush 25 EC) was studied. RESULTS: Coinjection of 50 ng permethrin with 80 pmol Pyrap-AKH induced a significant 2.3-fold increase in bug mortality compared with the insecticide alone. The results were confirmed by topical coapplication of both agents (400 ng and 80 pmol respectively). Injections of 50 and 100 ng permethrin elicited a significant increase in the AKH level in CNS and the haemolymph. The results indicate an involvement of AKH in stress response to permethrin. The enhanced effect of insecticide by AKH treatments probably results from the stimulatory role in bug metabolism: carbon dioxide production was increased 3.5- and 2.5-fold respectively 1 and 3 h after permethrin treatment, and 4.3- and 3.4-fold after the permethrin plus AKH cotreatment, compared with the control. CONCLUSION: The elevation of metabolism could intensify the permethrin action by its faster penetration into tissues and by stimulation of biochemically active cells, and could be a reason for enhanced action of permethrin after its cotreatment with Pyrap-AKH.

Adipokines in children with sleep disordered breathing.

STUDY OBJECTIVE: Associations between SDB, the metabolic syndrome, and circulating levels of adipokines have emerged in adults but have not been examined in snoring children, who, in contradistinction to adults, display insulin resistance and lipid abnormalities as a function of adiposity rather than SDB. Therefore, we aimed to examine associations between circulating adipokines levels, insulin resistance, and measures of SDB in children. DESIGN: Prospective study. SETTING: Polysomnographic evaluation and assessment of plasma levels of leptin, adiponectin, resistin, glucose, insulin, and CRP. PARTICIPANTS: 130 children (mean age 8.2 +/- 2.8 years; 39% obese) were studied. MEASUREMENTS AND RESULTS: Log adiponectin levels were lower in obese than nonobese children (3.8 +/- 0.31 vs 4.0 +/- 0.30 corresponding to 8,381.4 +/- 5,841.0 vs 12,853.2 +/- 7,780.2 ng/ml, P < 0.0001) and were inversely correlated with BMI Z scores (r = -0.47, P < 0.0001) but not with log AHI. Log leptin concentrations were higher in the obese group than the nonobese group (4.2 +/- 0.32 vs 3.4 +/- 0.57 corresponding to 19,542.6 +/- 13,643.6 vs 5,875.5 +/- 8,425.7 pg/ml, P < 0.0001), correlated with BMI Z scores (r = 0.64, P < 0.0001), and were significantly lower in children with AHI < or = 1/hr than children with AHI > 1/hr (P = 0.006) and in children with SpO2 nadir > or = 90% than children with SpO2 nadir < 90%, even after controlling for BMI Z score (P < 0.03). No significant differences were found in log resistin levels as a function of obesity or AHI. Significant correlations between log adiponectin levels and log Insulin/Glucose (I/G) ratios (-0.28, P = 0.006) and between log leptin levels and log I/G ratios (r = 0.66, P < 0.0001) emerged. CONCLUSIONS: In close agreement with the absence of a measurable effect of SDB on insulin resistance in children, circulating adipokines levels are primarily attributable to the ponderal index. However, SDB and associated hypoxemia may contribute to the elevation of leptin levels.

Blood glucose lowering by means of lifestyle intervention has different effects on adipokines as compared with insulin treatment in subjects with type 2 diabetes.

AIMS/HYPOTHESIS: Adipokines may be important in mediating signals from adipocytes to insulin-sensitive tissue and vasculature. We studied the effect of different glucose-lowering therapies on serum levels of plasminogen activator inhibitor-1 (PAI-1), high-sensitivity C-reactive protein (hs-CRP), TNF-alpha, leptin, adiponectin and ghrelin in patients with type 2 diabetes. SUBJECTS AND METHODS: Twenty-eight patients with poorly controlled type 2 diabetes who were receiving oral hypoglycaemic agents were allocated to one of the following groups, and treated for 1 year: (1) lifestyle intervention (L); (2) insulin treatment (I); and (3) combined treatment (L+I). RESULTS: Similar improvements in glycaemic control occurred in all three groups. There was a reduction in body weight of 3.0 kg (median) (95% CI -5.9 to -2.0) in group L, whereas in groups L+I and I body weight increased by 3.5 kg (95% CI 1.5-4.9) and 4.9 kg (95% CI -3.1 to 8.2), respectively. By trend analyses, group L had reduced levels of PAI-1 (p=0.002), hs-CRP (p<0.0001) and TNF-alpha (p=0.006), while no significant changes were observed in the levels of leptin or adiponectin. In group I, the median levels of PAI-1 (p=0.008), TNF-alpha (p=0.058) and leptin (p=0.004) increased. In the L+I group there was a reduction in PAI-1 levels (p=0.014) and an increase in levels of leptin (p<0.001). The differences in changes in the levels of PAI-1, hs-CRP, TNF-alpha and leptin between groups were also significant (all p<0.01). CONCLUSIONS/INTERPRETATION: Improvement of glycaemic control through lifestyle intervention in type 2 diabetes had more beneficial effects on adipokine levels than when the same lowering of HbA(1c) was achieved with insulin treatment.

Induced hyperlipaemia and immune challenge in locusts.

Injections of immunogens, such as beta-1,3-glucan or lipopolysaccharide (LPS), bring about a marked hyperlipaemia with associated changes in lipophorins and apolipophorin-III in the haemolymph of Locusta migratoria. These changes are similar to those observed after injection of adipokinetic hormone (AKH). The possibility that endogenous AKH is released as part of the response to these immunogens is investigated using passive immunisation against AKH-I, and measurement of AKH-I titre in the haemolymph after injection of immunogens. The data presented show that, despite the similarity of the changes brought about by the presence of immunogens in the haemolymph to those brought about by AKH, there is no release of endogenous AKH after injection of laminarin or LPS. A direct effect of the immunogens on release of neutral lipids by the fat body cannot be demonstrated in vitro, and the mechanism by which hyperlipaemia is induced during immune challenge remains uncertain.

Fat metabolism in insects.

The study of fat metabolism in insects has received considerable attention over the years. Although by no means complete, there is a growing body of information about dietary lipid requirements, and the absolute requirement for sterol is of particular note. In this review we (a) summarize the state of understanding of the dietary requirements for the major lipids and (b) describe in detail the insect lipid transport system. Insects digest and absorb lipids similarly to vertebrates, but with some important differences. The hallmark of fat metabolism in insects centers on the lipid transport system. The major lipid transported is diacylglycerol, and it is carried by a high-density lipoprotein called lipophorin. Lipophorin is a reusable shuttle that picks up lipid from the gut and delivers it to tissues for storage or utilization without using the endocytic processes common to vertebrate cells. The mechanisms by which this occurs are not completely understood and offer fruitful areas for future research.

Effects of social environment and worker mandibular glands on endocrine-mediated behavioral development in honey bees.

Previous studies suggest that older honey bee workers possess an inhibitory signal that regulates behavioral development in younger bees. To study how this inhibitor is transmitted, bees were reared for 7 days in double-screen cages, single-screen cages, or unrestricted in a typical colony (control bees). Double-screen cages prevented physical contact with colony members while single-screen cages allowed only antennation and food exchange. Bees reared in double-screen cages showed accelerated endocrine and behavioral development; they had significantly higher rates of juvenile hormone biosynthesis and juvenile hormone titers than did control bees and also were more likely to become precocious foragers. Relative to the other two groups, bees reared in single-screen cages showed intermediate juvenile hormone biosynthesis rates and titers, and intermediate rates of behavioral development. These results indicate that physical contact is required for total inhibition. We also began to test the hypothesis that worker mandibular glands are the sources of an inhibitory signal. Old bees with mandibular glands removed were significantly less inhibitory towards young bees than were sham-operated and unoperated bees. These results suggest that an inhibitor is produced by the worker mandibular glands.

Circulating levels of Locusta diuretic hormone: the effects of feeding.

A radioimmunoassay was developed using 125I-labeled-[TyrO]Locusta-DH and polyclonal antibodies raised against Locusta-DH (29-46). The assay had a detection limit of 50 pM, and displayed limited cross-reactivity for other CRF-related peptides, but not for unrelated peptides. About 60% of the total immunoreactive material in locust hemolymph was attributable to Locusta-DH. The circulating level of diuretic hormone increases fivefold in fed insects, sufficient to stimulate primary urine production, and is correlated with the duration of the meal. This is consistent with the role of Locusta-DH in the control of postfeeding diuresis.

Modular organization of the PDZ domains in the human discs-large protein suggests a mechanism for coupling PDZ domain-binding proteins to ATP and the membrane cytoskeleton.

The human homologue (hDIg) of the Drosophila discs-large tumor suppressor (DIg) is a multidomain protein consisting of a carboxyl-terminal guanylate kinase-like domain, an SH3 domain, and three slightly divergent copies of the PDZ (DHR/GLGF) domain. Here have examined the structural organization of the three PDZ domains of hDIg using a combination of protease digestion and in vitro binding measurements. Our results show that the PDZ domains are organized into two conformationally stable modules one (PDZ, consisting of PDZ domains 1 and 2, and the other (PDZ) corresponding to the third PDZ domain. Using amino acid sequencing and mass spectrometry, we determined the boundaries of the PDZ domains after digestion with endoproteinase Asp-N, trypsin, and alpha-chymotrypsin. The purified PDZ1+2, but not the PDZ3 domain, contains a high affinity binding site for the cytoplasmic domain of Shaker-type K+ channels. Similarly, we demonstrate that the PDZ1+2 domain can also specifically bind to ATP. Furthermore, we provide evidence for an in vivo interaction between hDIg and protein 4.1 and show that the hDIg protein contains a single high affinity protein 4.1-binding site that is not located within the PDZ domains. The results suggest a mechanism by which PDZ domain-binding proteins may be coupled to ATP and the membrane cytoskeleton via hDlg.

Ovarian and hemolymph ecdysteroids in the terrestrial isopod Armadillidium vulgare (Malacostracan Crustacea).

Ovarian and hemolymph ecdysteroids in Armadillidium vulgare were analyzed at four stages of ovarian maturation through the reproductive molt cycle using high-performance liquid chromatography and radioimmunoassay. The major ecdysteroids in the ovaries and hemolymph of A. vulgare were 20-hydroxyecdysone and ecdysone in free and conjugated forms. The concentration of ovarian ecdysteroids reached a maximal level in maturing ovaries during stage D (premolt period) of the molt cycle. At the end of stage D, a high level of ecdysteroids was detected in fully matured ovaries. On the other hand, hemolymph ecdysteroid titers in reproductive females showed a peak during stage D and declined rapidly to a low level at the end of stage D. No appreciable differences in the amounts of hemolymph ecdysteroids and in molecular species of them were apparent in females in reproductive and nonreproductive molt cycles. The amounts of hemolymph ecdysteroids were about fivefold higher in females than those in males. These ecdysteroids may have a role in controlling ovarian development in female A. vulgare.

Baculovirus replication alters hormone-regulated host development.

The baculovirus Lymantria dispar nuclear polyhedrosis virus interferes with insect larval development by altering the host's hormonal system. The level of haemolymph ecdysteroids, the insect moulting hormone, was found to be higher in virus-infected larvae than in uninfected controls. This was consistently observed in both fourth instars and day 5-infected fifth instars. The rate of hormone synthesis was examined by in vitro incubation of the prothoracic gland. Gland activity in virus-infected larvae was higher than controls and continued until the late stages of virus infection, even during the time that controls had ceased to secrete ecdysone after moulting. During virus replication, the prothoracic gland was observed to maintain morphological and ultrastructural characteristics indicative of ecdysone biosynthetic activities. Therefore, it is likely that the insects are no longer under the control of the normal hormonal system after virus infection. It is felt that the alteration of hormone titre and the rate of ecdysone synthesis is the result of the activity of ecdysteroid UDP-glucosyl transferase (EGT), a virus-encoded enzyme which is thought to inactivate ecdysteroids by sugar conjugation.

Extraction of the synthetic lytic peptide, cecropin B, from biological fluid and analysis using reversed-phase high-performance liquid chromatography.

The lytic peptide cecropin B, originally isolated from the giant silk moth Hyalophora cecropia, has been found to possess antibacterial and cell lysis properties in vitro and some anticancer activity in vivo. An HPLC method was developed to study synthetic cecropin B concentrations in biological fluids. Cecropin B was recovered from culture medium by solid-phase extraction (40.0 +/- 2.4%), whereas in plasma it was highly protein-bound. The peptide was dissociated from proteins by citric acid and recovered by ultrafiltration (64.6 +/- 5.9%) and was unstable in plasma (half-life, 0.57 +/- 0.11 h). These analytical methods will facilitate future in vivo pharmacokinetic studies.

Developmental changes in the prothoracicotropic hormone content of the Bombyx mori brain-retrocerebral complex and hemolymph: analysis by immunogold electron microscopy, quantitative image analysis, and time-resolved fluoroimmunoassay.

The insect brain neuropeptide, prothoracicotropic hormone (PTTH), elicits the molting process by stimulating ecdysteroidogenesis in the prothoracic glands. Changes in the subcellular distribution of PTTH during the fifth larval instar and larval-pupal metamorphosis of Bombyx were investigated using immunogold electron microscopy and computerized image analysis. A time-resolved fluoroimmunoassay was employed to quantify the hemolymph PTTH titer and the hemolymph ecdysteroid titer was determined by radioimmunoassay. Immunoreactivity was apparent only in the cytoplasm of two pairs of dorsal-lateral neurosecretory cells (La) in the brain, the prothoracicotropes, and their axons that traverse the peripheral area of the brain neuropil and then enter the neurohemal lobes of the corpora cardiaca and end in the corpora allata. Immunospecificity was evident as noted by the restriction of the 5-nm gold particles to the neurosecretory granules. Synaptic contacts were noted frequently between the dendritic collaterals of the prothoracicotropes and neighboring collaterals from other neurons. The morphological data suggest that PTTH is synthesized and released throughout the fifth larval instar. The concentration of gold particles in the neurosecretory granules and the number of neurosecretory granules increased five times during the fifth instar, and these increases were correlated with surges in the hemolymph PTTH and ecdysteroid titers. The data suggest that PTTH biosynthesis, secretory granule formation, and secretion are three continuous and almost synchronized events.

Isolation, characterization and developmental expression of the ecdysteroid-induced E75 gene of the wax moth Galleria mellonella.

Using the cDNA for the Drosophila ecdysteroid-induced member of the steroid-hormone-receptor superfamily, E75A, we isolated a genomic clone from Galleria mellonella that revealed 77% similarity with the region of E75A cDNA encoding the C-terminal zinc-finger motif. A Galleria cDNA clone was isolated that encoded a complete DNA-binding domain composed of two zinc fingers and designated GmE75A. Its deduced amino acid sequence showed 100% and 85% identities within the DNA-binding and ligand-binding domains of Drosophila E75A, respectively. The Galleria genomic clone did not encode the N-terminal zinc finger, but included a sequence similar to the B1 exon, which is unique to the B isoform of E75. Thus, the cDNA and genomic DNA sequences indicated that the Galleria gene E75 encoded at least two isoforms, GmE75A and GmE75B, which differed in their N-termini. Probes specific for GmE75A and B hybridized to two distinct transcripts of 2.6 kb. Both GmE75A and B mRNA levels correlated closely with the ecdysteroid titer during development. At the onset of larval/pupal transformation, both transcripts appeared in high amounts within 4 h of the ecdysteroid rise, then declined concurrently with the hormone titer decline. At the time of pupal ecdysis, there was another peak of GmE75A expression but not GmE75B expression, coincident with a minor ecdysteroid pulse. In isolated abdomens of final instar larvae, GmE75A mRNA was induced by 20-hydroxyecdysone within 20 min of the injection; the mRNA levels were maximal at 1 h and declined by 3 h following the treatment.

Selectivity in storage hexamerin clearing demonstrated with hemolymph transfusions between Hyalophora cecropia and Actias luna.

When Hyalophora cecropia hemolymph was injected into wandering Actias luna larvae, a methionine-rich hexamerin was selectively transferred to the host's fat body, and completely cleared from the hemolymph by the time of pupal eclosion. Donor arylphorin was 30-40% removed from the hemolymph, and riboflavin-binding hexamerin was even less completely cleared. During the pupal-adult molt, these rates were reversed: methionine-rich hexamerin disappeared no faster than bovine serum albumin, while riboflavin-binding hexamerin was rapidly and completely cleared from the hemolymph, even though A. luna hemolymph lacks a homologue of this protein; arylphorin, again, was cleared at an intermediate rate. Selective clearing of the three hexamerins occurred at similar stages in H. cecropia, their species of origin. Developmentally programmed clearing, with selectivity at least partially conserved between genera, was also demonstrated with transfused vitellogenin: in A. luna females that were forming yolk, H. cecropia vitellogenin was cleared more rapidly than bovine serum albumin; but in younger females, and in males at all stages of metamorphosis, this Mr 510,000 molecule was instead an indicator of nonselective, large protein clearing. Nonselective clearing was more complete during adult development than during pupation. It also showed signs of being more effective for small than for large proteins, insensitive to carbohydrate conjugates, and unsaturated at the protein levels used.