Sexual dimorphism in aipysurine sea snakes (Elapidae, Hydrophiinae)

The transition from terrestrial to aquatic life by hydrophiine elapid snakes modified targets of natural selection and likely affected sexual selection also. Thus, the shift to marine life also might have affected sexual dimorphism. Our measurements of 419 preserved specimens of six species of aipysurine snakes (genera Emydocephalus and Aipysurus) revealed sexual dimorphism in mean adult snout-vent length (SVL), body width relative to SVL, lengths and widths of heads and tails relative to SVL, and eye diameter relative to head length. Females averaged larger than males in all taxa, and generally were wider-bodied with shorter and wider tails and smaller eyes. For other traits, sexual dimorphism varied among species: for example, relative head length ranged from male-biased to female-biased, and head shape (width relative to length) was highly dimorphic only in A. laevis. The transition to marine life may have eliminated male-male combat (reducing selection for large males) and favoured visual rather than pheromone-based mate-searching (favouring larger eyes in males). Variation in head-size dimorphism may reflect intersexual niche partitioning, with different taxa following different trajectories. Repeated evolutionary transitions from terrestrial to aquatic life in snakes provide a powerful opportunity to explore selective forces on sexually dimorphic traits.

Ecological immunization: in situ training of free-ranging predatory lizards reduces their vulnerability to invasive toxic prey

In Australia, large native predators are fatally poisoned when they ingest invasive cane toads (Rhinella marina). As a result, the spread of cane toads has caused catastrophic population declines in these predators. Immediately prior to the arrival of toads at a floodplain in the Kimberley region, we induced conditioned taste aversion in free-ranging varanid lizards (Varanus panoptes), by offering them small cane toads. By the end of the 18-month study, only one of 31 untrained lizards had survived longer than 110 days, compared to more than half (nine of 16) of trained lizards; the maximum known survival of a trained lizard in the presence of toads was 482 days. In situ aversion training (releasing small toads in advance of the main invasion front) offers a logistically simple and feasible way to buffer the impact of invasive toads on apex predators.

The things they carried: The pathogenic effects of old and new parasites following the intercontinental invasion of the Australian cane toad (Rhinella marina)

Brought to Australia in 1935 to control agricultural pests (from French Guiana, via Martinique, Barbados, Jamaica, Puerto Rico and Hawai'i), repeated stepwise translocations of small numbers of founders enabled the cane toad (Rhinella marina) to escape many parasites and pathogens from its native range. However, the infective organisms that survived the journey continue to affect the dynamics of the toad in its new environment. In Australia, the native-range lungworm Rhabdias pseudosphaerocephala decreases its host's cardiac capacity, as well as growth and survival, but not rate of dispersal. The lungworm is most prevalent in long-colonised areas within the toads' Australian range, and absent from the invasion front. Several parasites and pathogens of Australian taxa have host-shifted to cane toads in Australia; for example, invasion-front toads are susceptible to spinal arthritis caused by the soil bacterium, Ochrobactrum anthropi. The pentastome Raillietiella frenata has host-shifted to toads and may thereby expand its Australian range due to the continued range expansion of the invasive toads. Spill-over and spill-back of parasites may be detrimental to other host species; however, toads may also reduce parasite loads in native taxa by acting as terminal hosts. We review the impact of the toad's parasites and pathogens on the invasive anuran's biology in Australia, as well as collateral effects of toad-borne parasites and pathogens on other host species in Australia. Both novel and co-evolved pathogens and parasites may have played significant roles in shaping the rapid evolution of immune system responses in cane toads within their invaded range.

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Invasive cane toads have lost many parasites due to serial translocations.

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One native lungworm (Rhabdias pseudosphaerocephala) has been retained.

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Toads have also acquired novel parasites and pathogens from Australian hosts.

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Toads either amplify parasite numbers or act as a parasite sink.

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Differences in immune function exist between toad populations within Australia.

An exploratory investigation of real-world reasoning in paranoia

OBJECTIVES

Paranoid thinking has been linked to greater availability in memory of past threats to the self. However, remembered experiences may not always closely resemble events that trigger paranoia, so novel explanations must be elaborated for the likelihood of threat to be determined. We investigated the ability of paranoid individuals to construct explanations for everyday situations and whether these modulate their emotional impact.

METHODS

Twenty-one participants experiencing paranoia and 21 healthy controls completed a mental simulation task that yields a measure of the coherence of reasoning in everyday situations.

RESULTS

When responses featured positive content, clinical participants produced less coherent narratives in response to paranoid themed scenarios than healthy controls. There was no significant difference between the groups when responses featured negative content.

CONCLUSIONS

The current study suggests that difficulty in scenario construction may exacerbate paranoia by reducing access to non-threatening explanations for everyday events, and this consequently increases distress.

Pathology of Runting in Farmed Saltwater Crocodiles (Crocodylus porosus) in Australia

Extremely poor growth of some individuals within a birth cohort (runting) is a significant problem in crocodile farming. We conducted a pathological investigation to determine if infectious disease is associated with runting in farmed saltwater crocodiles ( Crocodylus porosus) and to look for evidence of other etiologies. In each of 2005 and 2007, 10 normal and 10 runt crocodiles, with an average age of 5.5 months and reared under identical conditions, were sampled. Laboratory testing included postmortem; histological examination of a wide variety of tissues (with quantitation of features that were noted subjectively to be different between groups); hematology; serum biochemistry (total protein, albumin, globulins, total calcium, phosphorus, and iron); bacterial culture of liver and spleen (2005 only); viral culture of liver, thymus, tonsil, and spleen using primary crocodile cell lines (2007 only); and serum corticosterone (2007 only). The only evidence of infectious disease was mild cutaneous poxvirus infection in 45% of normal and 40% of runt crocodiles and rare intestinal coccidia in 5% of normal and 15% of runt crocodiles. Bacterial and viral culture did not reveal significant differences between the 2 groups. However, runt crocodiles exhibited significant ( P < .05) increases in adrenocortical cell cytoplasmic vacuolation and serum corticosterone, decreased production of bone (osteoporosis), and reduced lymphoid populations in the spleen, tonsil, and thymus. Runts also exhibited moderate anemia, hypoalbuminemia, and mild hypophosphatemia. Taken together, these findings suggest an association between runting and a chronic stress response (hyperactivity of the hypothalamic-pituitary-adrenal axis).

Spinal arthropathy associated with Ochrobactrum anthropi in free-ranging cane toads (Chaunus [Bufo] marinus) in Australia

Inflammatory or degenerative pathology involving the vertebral bodies and/or ventral intervertebral joints has been described in numerous species, both captive and free ranging, including mammals, birds, and snakes, although never in amphibians. We described 15 cases of a newly recognized spinal arthropathy in adult cane toads (Chaunus [Bufo] marinus), an invasive species in Australia. Grossly appreciable lesions consisted primarily of ventral proliferation of bone and cartilage that resulted in ankylosis. Histologic examination of the entire vertebral columns of the 15 affected toads revealed 13 toads to have lesions at multiple intervertebral sites, totalling 41 intervertebral joints with lesions. Most lesions involved bone and cartilage proliferation that resulted in fusion of the joint, with (n = 15) or without (n = 9) associated pyogranulomatous inflammation. In the remaining 17 affected joints, histologic lesions were characterized by degeneration of articular cartilage without joint fusion. In addition, in one of these joints, there was also hemorrhage and pyogranulomatous inflammation. Bacterial culture of affected joints in 9 toads and grossly normal joints in 4 control toads resulted in isolation of Ochrobactrum anthropi in 7 affected toads but in none of the controls (P < .01). We proposed an interaction between degenerative and bacterial etiologies in the pathogenesis of this condition. Invasive toads may be predisposed to this condition because of their large size; increased rates of movement; and, possibly, immunosuppression resulting from inhabiting a novel environment.

Repeatability and heritability of reproductive traits in free-ranging snakes

The underlying genetic basis of life-history traits in free-ranging animals is critical to the effects of selection on such traits, but logistical constraints mean that such data are rarely available. Our long-term ecological studies on free-ranging oviparous snakes (keelbacks, Tropidonophis mairii (Gray, 1841), Colubridae) on an Australian floodplain provide the first such data for any tropical reptile. All size-corrected reproductive traits (egg mass, clutch size, clutch mass and post-partum maternal mass) were moderately repeatable between pairs of clutches produced by 69 female snakes after intervals of 49-1152 days, perhaps because maternal body condition was similar between clutches. Parent-offspring regression of reproductive traits of 59 pairs of mothers and daughters revealed high heritability for egg mass (h2= 0.73, SE=0.24), whereas heritability for the other three traits was low (< 0.37). The estimated heritability of egg mass may be inflated by maternal effects such as differential allocation of yolk steroids to different-sized eggs. High heritability of egg size may be maintained (rather than eroded by stabilizing selection) because selection acts on a trait (hatchling size) that is determined by the interaction between egg size and incubation substrate rather than by egg size alone. Variation in clutch size was mainly because of environmental factors (h2=0.04), indicating that one component of the trade-off between egg size and clutch size is under much tighter genetic control than the other. Thus, the phenotypic trade-off between egg size and egg number in keelback snakes occurs because each female snake must allocate a finite amount of energy into eggs of a genetically determined size.

WHY DO MOST TROPICAL ANIMALS REPRODUCE SEASONALLY? TESTING HYPOTHESES ON AN AUSTRALIAN SNAKE

Most species reproduce seasonally, even in the tropics where activity occurs year-round. Squamate reptiles provide ideal model organisms to clarify the ultimate (adaptive) reasons for the restriction of reproduction to specific times of year. Females of almost all temperate-zone reptile species produce their eggs or offspring in the warmest time of the year, thereby synchronizing embryogenesis with high ambient temperatures. However, although tropical reptiles are freed from this thermal constraint, most do not reproduce year-round. Seasonal reproduction in tropical reptiles might be driven by biotic factors (e.g., peak periods of predation on eggs or hatchlings, or food for hatchlings) or abiotic factors (e.g., seasonal availability of suitably moist incubation conditions). Keelback snakes (Tropidonophis mairii, Colubridae) in tropical Australia reproduce from April to November, but with a major peak in May-June. Our field studies falsify hypotheses that invoke biotic factors as explanations for this pattern: the timing of nesting does not minimize predation on eggs, nor maximize food availability or survival rates for hatchlings. Instead, our data implicate abiotic factors: female keelbacks nest most intensely soon after the cessation of monsoonal rains when soils are moist enough to sustain optimal embryogenesis (wetter nests produce larger hatchlings, that are more likely to survive) but are unlikely to become waterlogged (which is lethal to eggs). Thus, abiotic factors may favor seasonal reproduction in tropical as well as temperate-zone animals.

Expression of Q227L-Galpha(s) inhibits intimal vessel wall hyperplasia after balloon injury

Interaction between signaling pathways regulates many cellular functions, including proliferation. The Galpha(s)/cAMP pathway is known to inhibit signal flow from receptor tyrosine kinases to mitogen-activated protein kinase (MAPK)-1,2 and, thus, inhibit proliferation. Elevation of cAMP or adenovirus-directed expression of mutant (Q227L)-Galpha(s) (alpha(s)*) inhibits the proliferation of rat vascular smooth muscle cells (VSMCs) in culture. Platelet-derived growth factor (PDGF) stimulated MAPK activation and DNA synthesis was also blocked by expression of alpha(s)*. However, it is not known whether such mechanisms are operative in vivo. Proliferation of vascular smooth muscle cells in vivo was induced by balloon injury of carotid arteries in the rat. Recombinant adenovirus encoding beta-galactosidase (beta-gal) or alpha(s)* was applied to arterial segments injured by the balloon catheters. The alpha(s)*-treated vessels showed decreased phospho-MAPK staining in the intima as compared with beta-gal-treated vessels. Application of alpha(s)*, but not beta-gal containing adenovirus, inhibited formation of neointima by 50%. No change was observed in total vessel diameter or in the media or adventitia. These results suggest that the interaction between the Galpha(s) and MAPK pathways can regulate proliferation in vivo and that targeted expression of activated Galpha(s) may have therapeutic potential for the treatment of vascular pathophysiologies that arise from intimal hyperplasia.

Long-term potentiation induced by theta frequency stimulation is regulated by a protein phosphatase-1-operated gate

Long-term potentiation (LTP) can be induced in the Schaffer collateral-->CA1 synapse of hippocampus by stimulation in the theta frequency range (5-12 Hz), an effect that depends on activation of the cAMP pathway. We investigated the mechanisms of the cAMP contribution to this form of LTP in the rat hippocampal slice preparation. theta pulse stimulation (TPS; 150 stimuli at 10 Hz) by itself did not induce LTP, but the addition of either the beta-adrenergic agonist isoproterenol or the cAMP analog 8-bromo-cAMP (8-Br-cAMP) enabled TPS-induced LTP. The isoproterenol effect was blocked by postsynaptic inhibition of cAMP-dependent protein kinase. Several lines of evidence indicated that cAMP enabled LTP by blocking postsynaptic protein phosphatase-1 (PP1). Activators of the cAMP pathway reduced PP1 activity in the CA1 region and increased the active form of inhibitor-1, an endogenous inhibitor of PP1. Postsynaptic injection of activated inhibitor-1 mimicked the LTP-enabling effect of cAMP pathway stimulation. TPS evoked complex spiking when isoproterenol was present. However, complex spiking was not sufficient to enable TPS-induced LTP, which additionally required the inhibition of postsynaptic PP1. PP1 inhibition seems to promote the activation of Ca(2+)/calmodulin-dependent protein kinase (CaMKII), because (1) a CaMKII inhibitor blocked the induction of LTP by TPS paired with either isoproterenol or activated inhibitor-1 and (2) CaMKII in area CA1 was activated by the combination of TPS and 8-Br-cAMP but not by either stimulus alone. These results indicate that the cAMP pathway enables TPS-induced LTP by inhibiting PP1, thereby enhancing Ca(2+)-independent CaMKII activity.

Thromboxane receptors in human kidney tissues

Thromboxane (TX) A2 effects in the kidneys include contraction of glomerular mesangial cells and intrarenal vascular tissue. A kidney cDNA encoding a TX receptor expressed in rat renal glomeruli and rat renal arterial smooth muscle cells has been reported. However, TXA2 receptors in human kidneys have not been documented. The purpose of this study was to identify and characterize TXA2 receptors in glomeruli and intrarenal arteries isolated from human kidneys. Normal kidneys, not used for transplant because of technical reasons, were kept at -70 degrees C and used for research purposes. The glomeruli and intrarenal arteries were isolated from renal cortical tissue by a mechanical sieving technique. The equilibrium dissociation constant and receptor number were determined by nonlinear analysis of binding inhibition data. The data were generated in radioreceptor assays using [125I]-BOP, a stable analog of TXA2. The dissociation constants (mean +/- SEM) for binding of I-BOP to human glomeruli and intrarenal arterial membranes were 6.6 +/- 1.1 nM (n = 7) and 20 +/- 6 nM (n = 7), respectively (p < 0.05). The receptor number was 311 +/- 91 fmol/mg protein (n = 7) in glomeruli and 74 +/- 16 fmol/mg protein (n = 7) in intrarenal arterial membranes (p < 0.04). The order of specificity of TXA2 analogs for [125I]-BOP binding sites was similar in glomeruli and in arterial membranes and was I-BOP > or = U46619 > or = pinane TXA2 > or = carbocyclic TXA2 > or = PGH2. These findings provide direct evidence for the presence of specific, high-affinity [125I]-BOP binding sites in human renal glomeruli and extraglomerular vascular tissue. These data also indicate that the human binding sites have higher affinity for the TXA2 agonist I-BOP than for PGH2.

3H-naloxone benzoylhydrazone binding in MOR-1-transfected Chinese hamster ovary cells: evidence for G-protein-dependent antagonist binding

Naloxone benzoylhydrazone (NalBzoH) is a potent mu antagonist in vivo. In a cell line stably transfected with MOR-1 (CHO/MOR-1), NalBzoH also was an antagonist when examined in adenylyl cyclase studies. In binding studies, it displayed high affinity for the mu receptor, confirming its earlier characterization in brain membranes. In competition studies under equilibrium conditions, NalBzoH and diprenorphine both retained their potency in the presence of the stable GTP analog 5'-guanylylimidophosphate, consistent with their mu antagonist properties, whereas the agonist DAMGO showed more than a 3-fold loss of affinity. The dissociation of 3H-diprenorphine was monophasic. However, kinetic studies revealed biphasic dissociations for both 3H-NalBzoH and 3H-DAMGO. The slow component of 3H-NalBzoH dissociation, corresponding to the higher affinity state, was dependent on coupling to G-proteins. It is selectively abolished by guanine nucleotides, leaving only the rapid dissociation phase. Furthermore, the slow dissociation component is eliminated by treatment of the cells with pertussis toxin, but not cholera toxin. In conclusion, NalBzoH is an unusual opioid. Functionally it is an antagonist, a classification consistent with its equilibrium binding in the presence of guanine nucleotides. Yet, kinetic studies reveal that it labels a G-protein coupled state of the receptor with high affinity.

Gating of CaMKII by cAMP-regulated protein phosphatase activity during LTP

Long-term potentiation (LTP) at the Schaffer collateral-CA1 synapse involves interacting signaling components, including calcium (Ca2+)/calmodulin-dependent protein kinase II (CaMKII) and cyclic adenosine monophosphate (cAMP) pathways. Postsynaptic injection of thiophosphorylated inhibitor-1 protein, a specific inhibitor of protein phosphatase-1 (PP1), substituted for cAMP pathway activation in LTP. Stimulation that induced LTP triggered cAMP-dependent phosphorylation of endogenous inhibitor-1 and a decrease in PP1 activity. This stimulation also increased phosphorylation of CaMKII at Thr286 and Ca2+-independent CaMKII activity in a cAMP-dependent manner. The blockade of LTP by a CaMKII inhibitor was not overcome by thiophosphorylated inhibitor-1. Thus, the cAMP pathway uses PP1 to gate CaMKII signaling in LTP.

Interaction of gender and dietary protein on renal growth and the renal growth hormone-insulin-like growth factor axis

The female kidney tends to be smaller, have a lower glomerular filtration rate, and be less susceptible to glomerulosclerosis than the male kidney. Insulin-like growth factor-I (IGF-I) is a peptide growth factor that appears to be important for normal and adaptive kidney growth. The purpose of this study was to compare the kidney growth response of the male and female rat kidneys to increased dietary protein intake and to see whether differences in IGF-I production or receptor expression might underlie any gender differences seen. Male (M) and female (F) Munich-Wistar rats (6 to 9 weeks of age) were randomized to isocaloric diets containing either 20% (NP) or 50% (HP) protein and studied after 3 and 14 days. In the male rat, wet kidney weight was significantly increased with HP at both day 3 (M-HP 1028+/-21 mg vs M-NP 891+/-19 mg, p < 0.01) and day 14 (M-HP 1499+/-41 mg vs M-NP 1246 +/-37 mg, p < 0.01). In contrast in the female rat, while there was evidence of initial increased growth at day 3 in the kidneys of F rats fed HP (F-HP 788+/-39 mg vs F-NP 650+/-23 mg, p < 0.01), this difference was not sustained at 14 days (F-HP 961+/-67 mg vs F-NP 931+/-71 mg, p = NS). At day 3, kidneys of both male and female rats fed HP exhibited an increase in total protein but not DNA content. The kidneys of male rats showed increased protein/DNA ratios in the medulla and inner cortex, whereas in the kidneys of female rats, the increase in protein/DNA ratio was confined to the cortex. After 14 days of HP ingestion, the kidneys of male rats showed increases in total kidney content of both DNA and protein, and protein/DNA ratios returned to control values in whole kidney, inner cortex, and medulla. In contrast, in the kidneys of female rats, not only was overall growth response reduced, but neither total kidney protein content nor DNA content was increased. Increased protein/DNA ratios were seen in inner cortex and in outer and inner medulla, similar to that seen at day 3 in the kidneys of male rats. Neither baseline plasma (M-NP 793+/-10 ng/ml, F-NP 704+/-32 ng/ml, p = NS) nor kidney IGF-I content (M-NP 520+/-55 ng/gm tissue, F-NP 506+/-54 ng/gm tissue, p = NS) differed between male and female rats fed NP diets. Both male and female rats showed a comparable increase in kidney IGF-I after 3 days of HP ingestion, and kidney IGF-I returned to control values by 14 days. There was no significant difference in the number or affinity of glomerular IGF-I receptors between male and female rats. In conclusion, we have shown that in the adult male rat, an increase in dietary protein ingestion results in a sustained increase in kidney size that is initially consistent with a hypertrophic response but subsequently shows elements of hyperplasia. In contrast, in the female rat, although there was evidence of the initial hypertrophic (and IGF-I) responses to increased dietary protein, the increase in kidney size was not sustained. However, these profound gender-based differences in the growth response to dietary protein did not appear to be due to differences in kidney expression of IGF-I or its receptors.

3H-morphine-6beta-glucuronide binding in brain membranes and an MOR-1-transfected cell line

Morphine-6beta-glucuronide (M6G) is a potent morphine metabolite. In an effort to further explore its mechanisms of action, we synthesized 3H-M6G of high specific activity and examined its binding. Although its affinity toward traditional mu receptors is similar to morphine in binding assays in brain and in Chinese hamster ovary cells stably transfected with MOR-1, M6G is >100-fold more potent than morphine in analgesic assays. This apparent discrepancy cannot be explained by differing intrinsic activities of the two drugs because both agents are partial agonists with similar efficacies in adenylyl cyclase assays in the transfected cell lines. Behavioral studies have implied the possibility of a distinct M6G receptor. Detailed binding studies in brain tissue reveal evidence for heterogeneity. Nonlinear regression analysis of 3H-M6G saturation studies reveals two components. The lower-affinity component (K(D) = 1.93 +/- 0.6 nM) corresponds to labeling of traditional mu receptors. In addition, 3H-M6G labels another site of low abundance with very high affinity (K(D) = 68 +/- 7 pM). Competition studies indicate that both sites are relatively mu selective. However, several compounds clearly distinguish between the two sites. These binding studies support the concept of a unique M6G receptor responsible for its analgesic activity.

3-Methoxynaltrexone, a selective heroin/morphine-6beta-glucuronide antagonist

Recent work has suggested that heroin and morphine-6beta-glucuronide (M6G) both act through a novel mu opioid receptor subtype distinct from those mediating morphine's actions. This very high affinity 3H-M6G site is selectively competed by 3-methoxynaltrexone. In vivo, 3-methoxynaltrexone (2.5 ng, i.c.v.) selectively antagonizes the analgesic actions of heroin and M6G without interfering with mu (morphine and [D-Ala2,MePhe4,Gly(ol)5]enkephalin), delta ([D-Pen2,D-Pen5]enkephalin), kappa1 (U50,488H) or kappa3 (naloxone benzoylhydrazone) analgesia. In dose-response studies, 3-methoxynaltrexone (2.5 ng, i.c.v.) significantly shifted the ED50 values for heroin and its active metabolite, 6-acetylmorphine, without affecting the morphine curve. These results indicate that 3-methoxynaltrexone selectively blocks a novel 3H-M6G binding site which is responsible for the analgesic actions of heroin and M6G. This ability to selectively antagonize heroin actions opens new possibilities in the development of therapeutics for the treatment of opioid abuse.

Synthesis and characterization of [125I]3'-(-)-iodopentazocine, a selective sigma 1 receptor ligand

Pentazocine is a potent ligand at both opioid and sigma receptors, but with opposite stereoselectivities. Whereas (-)-pentazocine has high affinity for a number of opioid receptors, (+)-pentazocine labels sigma 1 receptors. Iodination of (-)-pentazocine at the 3'-position reverses its selectivity for opioid and sigma 1 receptors. 3'-(-)-Iodopentazocine competes at sigma 1 receptor binding sites with a Ki value of 8 nM, compared to approximately 40 nM for (-)-pentazocine. 3'-(-)-Iodopentazocine also has lost its affinity for opioid receptors. In contrast, iodination of (+)-pentazocine lowers its affinity at sigma 1 receptors. Synthesis of [125I]3'-(-)-iodopentazocine is readily performed with incorporations of up to 80%. Binding is of high affinity and shows the selectivity anticipated for a sigma 1 receptor-selective ligand. Exposing membranes prebound with [125I]3'-(-)-iodopentazocine to ultraviolet light can covalently couple the ligand into the membranes. Polyacrylamide gel electrophoresis reveals a major band at about 25 kDa and a minor one at about 20 kDa, indicating photolabeling of sigma 1 receptors with minor incorporation into sigma 2 sites.

Synthesis and characterization of substituted benzoylhydrazones of naloxone

Naloxone benzoylhydrazone (NalBzoH) has proved a valuable tool in the investigation of opioid receptor subtypes. In the present study, we have examined a series of derivatives of NalBzoH in which substitutions have been made on the benzoyl ring. Overall, we see dramatic effects on the binding affinities of derivatives against the various opioid receptor subtypes. Although the range of affinities against the mu receptors is quite modest, ranges of the others vary almost 30-fold for kappa 3, 50-fold for kappa 1 and 100-fold for delta and kappa 2 binding. Few substituted derivatives display greater affinity than NalBzoH for any of the receptors, except for delta sites where several derivatives have affinities almost tenfold greater than NalBzoH. Along with the wide variations in affinity, the compounds also appear to exhibited widely divergent activities in traditional bioassays.

Novel receptor mechanisms for heroin and morphine-6 beta-glucuronide analgesia

The rapid metabolism of heroin to 6-acetylmorphine and its slower conversion to morphine has led many to believe that heroin and morphine act through the same receptors and that the differences between them are due to their pharmacokinetics. We now present evidence strongly implying that heroin and two potent mu drugs, fentanyl and etonitazine, act through a unique receptor mechanism similar to morphine-6 beta-glucuronide which is readily distinguished from morphine. Heroin, 6-acetylmorphine and morphine-6 beta-glucuronide show no analgesic cross tolerance to morphine in a daily administration paradigm, implying distinct receptors. Strains also reveal analgesic differences among the drugs. CXBK mice, which are insensitive to morphine, retain their analgesic sensitivity to heroin, 6-acetylmorphine, morphine-6 beta-glucuronide, fentanyl and etonitazine. Antisense mapping of the mu opioid receptor MOR-1 reveals that oligodeoxynucleotide probes against exon 2, which are inactive against morphine analgesia, block morphine-6 beta-glucuronide, heroin, fentanyl and etonitazine analgesia. Finally, an antisense probe targeting Gi alpha 1 blocks both heroin and morphine-6 beta-glucuronide, but not morphine, analgesia. These results indicate that heroin, 6-acetylmorphine, fentanyl and etonitazine all can produce analgesia through a novel mu analgesic system which is similar to that activated by morphine-6 beta-glucuronide.

Dimensions of dysfunctional attitudes as vulnerabilities to depressive symptoms

Empirical tests of the diathesis-stress component of A. T. Beck's (1976; A. T. Beck, A. J. Rush, B. F. Shaw, & G. Emery, 1979) cognitive theory of depression have generally not yielded positive results. The resulting focus on conceptual and methodological concerns has diverted attention from the more fundamental issue of how validly vulnerability is measured. The present investigation uses the Dysfunctional Attitude Scale (DAS; A. N. Weissman, 1979; A. N. Weissman & Beck, 1978), the most commonly used measure of vulnerability in this area, but adopts a more in-depth approach by examining DAS factors in addition to the typical total score. This study involved a sample of undergraduates who had never before taken a college-level examination. The dimension of the DAS measured by the Perfectionistic Achievement factor had the strongest relationship to increased depressive symptoms in response to poorer-than-expected performance on the examination. Implications for future research in this area are discussed.

Antisense mapping the MOR-1 opioid receptor: evidence for alternative splicing and a novel morphine-6 beta-glucuronide receptor

Although MOR-1 encodes a mu opioid receptor, its relationship to the pharmacologically defined mu receptor subtypes has been unclear. Antisense mapping now suggests that these subtypes result from alternative splicing of MOR-1. Three oligodeoxynucleotide probes targeting exon 1 and another oligodeoxynucleotide directed against the coding region of exon 4 block supraspinal morphine analgesia, a mu1 action, while five of six oligodeoxynucleotides directed against exons 2 and 3 are inactive. Inhibition of gastrointestinal transit and spinal morphine analgesia, two mu2 actions, are blocked only by the probe against exon 4 and not by those directed against exon 1. In contrast, the analgesic actions of the extraordinarily potent mu drug morphine-6 beta-glucuronide are blocked by six different antisense oligodeoxynucleotides targeting exons 2 and 3, but not by those acting on exons 1 or 4. These results suggest that the mu1 and mu2 receptor subtypes originally defined in binding and pharmacological studies result from alternative splicing of MOR-1 while morphine-6 beta-glucuronide acts through a novel, previously unidentified receptor which is yet another MOR-1 splice variant.

Dimensions of dysfunctional attitudes as vulnerabilities to depressive symptoms

Empirical tests of the diathesis-stress component of A. T. Beck's (1976; A. T. Beck, A. J. Rush, B. F. Shaw, & G. Emery, 1979) cognitive theory of depression have generally not yielded positive results. The resulting focus on conceptual and methodological concerns has diverted attention from the more fundamental issue of how validly vulnerability is measured. The present investigation uses the Dysfunctional Attitude Scale (DAS; A. N. Weissman, 1979; A. N. Weissman & Beck, 1978), the most commonly used measure of vulnerability in this area, but adopts a more in-depth approach by examining DAS factors in addition to the typical total score. This study involved a sample of undergraduates who had never before taken a college-level examination. The dimension of the DAS measured by the Perfectionistic Achievement factor had the strongest relationship to increased depressive symptoms in response to poorer-than-expected performance on the examination. Implications for future research in this area are discussed.

Case study: the painful os trigonum syndrome

The painful os trigonum syndrome is one cause of posterolateral ankle pain. This syndrome is most prevalent in athletes who perform frequent and/or forceful plantar flexion. The painful os trigonum may be misdiagnosed as Achilles and/or peroneal tendinitis. In this case, the patient was misdiagnosed for 15 months and treated for tendinitis. The appropriate clinical tests to evaluate the os trigonum as a source of posterolateral ankle pain are outlined. The surgical and postoperative management for the patient are discussed. Clinicians should be aware of the painful os trigonum syndrome as a possible source of posterolateral ankle pain.

The effect of two types of foot orthoses on rearfoot mechanics

Little experimental data exist regarding the comparative biomechanical of various foot orthoses. This study evaluated the comparative effect of biomechanical orthoses and over-the-counter arch supports on controlling rearfoot pronation. Twenty-four patients with forefoot varus deformity were studied while walking on a treadmill. Two-dimensional, videotape motion analysis was used for studying rearfoot mechanics with three experimental conditions: 1) shoes only, 2) shoes plus arch supports, and 3) shoes plus biomechanical orthoses. The variables studied were: maximum pronation, calcaneal eversion, maximum pronation velocity, time-to-maximum pronation, and total pronation. No difference was noted in maximum pronation, calcaneal eversion, and total pronation between the three conditions. The data for maximum pronation velocity and time-to-maximum pronation were not reliable. Based on the results of this study, padded arch supports nor biomechanical orthoses can be preferentially recommended for their ability to control maximum pronation, calcaneal eversion, and total pronation during walking. Additional research is necessary to: 1) identify the biomechanical effects that are responsible for the clinical success of foot orthoses, and 2) determine better designs for controlling rearfoot movement.

Consequences of feminization of a profession: the case of Canadian pharmacy

Although the influx of women into formerly entirely male-dominated professions has attracted much commentary from members of these professions, little investigation of the consequences of rapid, large-scale feminization has been undertaken for particular professions. The results of a pilot study in Canadian pharmacy suggest that fears of shortages due to women working part-time while they raise their children, are unfounded. However, our survey results suggest that women are differentially drawn into pharmacies run by corporations rather than independent businesses. This may allow them to reorient pharmacy away from its business base and towards its chosen new professional jurisdiction of counselling. On the other hand, the demise of independent pharmacy, that traditionally attracted males, may bring with it less control by pharmacists over what they do in everyday practice. The possibility that similar processes are operating in other feminizing professions with entrepreneurial components, such as dentistry and optometry, should be investigated.

Selective loss of delta opioid analgesia and binding by antisense oligodeoxynucleotides to a delta opioid receptor

Antisense oligodeoxynucleotides (18-20 bases) to a cloned delta opioid receptor (DOR-1) lower delta binding in NG108-15 cells by 40%-50%. Changing 4 bases to generate a mismatch antisense oligodeoxynucleotide or mixing the corresponding sense and antisense oligodeoxynucleotides prior to treatment of the cells eliminates the inhibition of binding, confirming the specificity of the response. In vivo, an antisense oligodeoxynucleotide to DOR-1 given intrathecally lowers delta, but not mu or kappa 1 spinal analgesia. The mismatch antisense oligodeoxynucleotide is inactive. Delta analgesic sensitivity gradually returns by 5 days after the last antisense treatment, indicating the lack of irreversible damage or toxicity. These studies demonstrate that DOR-1 mediates delta analgesia at the level of the spinal cord and confirm at the molecular level traditional pharmacological studies implying distinct receptor mechanisms for delta, mu, and kappa 1 analgesia. The use of antisense approaches may prove valuable in understanding the receptors mediating opioid pharmacology.

Hospital and community pharmacists' attitudes towards clinical pharmacy

This longitudinal study compared the attitudes of the Class of 1983 at the University of Toronto toward clinical pharmacy seven years after graduation with those they expressed at the point of graduation in 1983. Over three quarters of the original class responded by indicating agreement or disagreement with statements (on a 5-point scale) about clinical pharmacy in 1983 and 1989. While there was little difference between those who became hospital pharmacists versus those who became community pharmacists at the point of graduation, seven years later, the hospital pharmacists were significantly more favourable than their colleagues toward drug consulting aspects of clinical pharmacy. The community pharmacists were significantly more favourable than their colleagues toward patient counselling aspects of clinical pharmacy. It is concluded that the work setting has influenced these different preferences for how the ideal of clinical pharmacy is interpreted. We offer a possible explanation for the consistently positive, if divergent, orientations towards the ideal of clinical pharmacy.

Effect of dietary fat on glomerular lipid composition and angiotensin II receptors

Nutritional factors are major etiologic determinants which may affect the incidence or severity of hypertension. Since angiotensin II (Ang II) has a role in some forms of hypertension, the influence of dietary lipid composition on glomerular lipid content and on Ang II receptor parameters was determined. Three groups of rats were fed diets containing 14% by weight of 1) beef fat (saturated fatty acid rich), 2) safflower oil (n-6 fatty acid rich), or 3) fish oil (n-3 fatty acid rich), each supplemented with 2% corn oil. A fourth group of rats was fed rat chow which contained 6.5% fat. At the end of 7 weeks, the rats were sacrificed, the kidneys removed, and renal glomeruli isolated using a sieving technique. Feeding diets which varied in the quantity and composition of fatty acids altered glomerular fatty acid composition of n-6 and n-3 fatty acids and the unsaturation indices of glomeruli. The cholesterol content, but not the phospholipid content, was decreased in glomeruli of animals fed the high fat diets. This resulted in a lower cholesterol/phospholipid ratio, indicative of an increase in membrane fluidity. Glomerular binding was determined using 125I-Ang II in a radioreceptor assay. Binding was proportional to glomerular protein and was time dependent. Receptor affinity (Ka) and number were determined by Scatchard analysis of binding inhibition data. Glomerular Ka was significantly lower for animals fed the rat chow as compared to the semisynthetic diets. There was no significant difference in the concentration of Ang II receptors in glomeruli of animals fed the different diets. The data indicate that the induced alteration in glomerular lipid composition is associated with alteration in the binding affinity of glomerular Ang II receptors.

Renal blood flow response to angiotensin II infusions in conscious pregnant rabbits

Renal blood flow (RBF) was measured in conscious rabbits while nonpregnant and during pregnancy using chronically implanted ultrasonic transit-time flow probes. The effects of the cyclooxygenase inhibitor meclofenamate (5 mg/kg) and the angiotensin-converting-enzyme inhibitor captopril (5 mg/kg) on basal RBF and on RBF responses to systemic angiotensin II infusions (2.5-80 ng.kg-1.min-1) were determined. Basal RBF declined (P less than 0.001 to P less than 0.005) with meclofenamate by 9-16% in pregnant (n = 7) and by 10% in nonpregnant (n = 7) rabbits. Captopril increased (P less than 0.05 to P less than 0.01) RBF by 9-11% in pregnant (n = 5) and by 12% in nonpregnant (n = 5) rabbits. There was no effect of the vehicle (normal saline) on RBF. The reduction in RBF (% from baseline) in response to infused angiotensin II was attenuated in pregnant compared with nonpregnant rabbits. Pretreatment with meclofenamate enhanced the renal vasoconstrictor action of angiotensin II in a similar fashion in both pregnant and nonpregnant rabbits. Captopril or saline did not alter the RBF responses to angiotensin II infusions. Mean arterial pressure was lower in pregnant (78 +/- 3 mmHg, n = 7) vs. nonpregnant (88 +/- 5 mmHg, n = 10) rabbits, suggesting lower total peripheral resistance. The data indicate 1) chronically implanted ultrasonic flow probes can be an effective tool for monitoring RBF in conscious rabbits, 2) prostaglandins and the renin-angiotensin system influence basal RBF in conscious rabbits, and 3) the renal vasoconstrictor effect of angiotensin II is blunted in pregnant rabbits and this attenuated response appears to be independent of prostaglandins.

Eicosanoid production in rabbit vascular tissues and placentas

In pregnant rabbits, systemic levels of prostaglandin E2 (PGE2) are elevated. To evaluate the source of the rise in circulating levels of PGE2, eicosanoid production was determined in rabbit placental cotyledons and the following vascular tissues: mesenteric arteries, main renal arteries, and intrarenal preglomerular vessels (n = 6 or 7 rabbits). Comparisons were made with vascular tissues from nonpregnant rabbits (n = 6 or 7). Freshly isolated tissues were incubated for 15 min at 37 degrees C. Medium aliquots were analyzed for eicosanoids by radioimmunoassay. Maximal net production and release (pg/microgram protein) was determined by subtraction of the quantity of eicosanoids present in medium before incubation from that present at the end of incubation. Net production and release of 6-ketoprostaglandin F1 alpha (PGF1 alpha), a stable metabolite of prostacyclin, and of PGE2 was similar in vascular tissues from pregnant and nonpregnant rabbits. Thromboxane B2 (TxB2) generation in preglomerular vessels from pregnant rabbits was lower (P less than 0.05) than that of nonpregnant rabbits. This could contribute to renal vasodilation in pregnancy. The pattern of eicosanoid production in vascular tissues was 6-keto-PGF1 alpha greater than PGE2 greater than TxB2, and in cotyledons it was PGE2 greater than 6-keto-PGF1 alpha greater than TxB2. In cotyledons, PGE2 and TxB2 production was 56-219 and 2-12 times that in maternal vascular tissues, respectively. These data suggest that physiologically significant quantities of eicosanoids may be released by rabbit placental tissue.

Effect of protein intake on the autoregulation of renal blood flow

Autoregulatory ability was evaluated in male Sprague-Dawley rats (200-250 g) fed either low protein (LP, 6%), high protein (HP, 50%), or standard rat chow (CON) for 2 wk. Renal perfusion pressure (RPP) was first raised above normal by bilateral ligation of the carotid arteries. LP rats exhibited normal autoregulatory behavior between 130 and 100 mmHg, whereas autoregulation in HP rats was impaired (autoregulation factor 100-130; HP 0.86 +/- 0.16, LP 0.38 +/- 0.07, and CON 0.39 +/- 0.04). Autoregulation studies were repeated in HP- and LP-fed rats after administration of the cyclooxygenase inhibitors, meclofenamate and piroxicam. Cyclooxygenase inhibition did not significantly affect base-line hemodynamics but did restore the ability of the HP rat to autoregulate renal blood flow (RBF) at high RPP. (Autoregulation factor between 100 and 130 mmHg; HP 0.29 +/- 0.10, LP 0.19 +/- 0.07, P, NS). Thus an HP diet resulted in impaired autoregulation of RBF at high RPP, an effect that appears to be mediated by excessive production of vasodilatory prostaglandins.

Cigarette smoking decreases interleukin 1 release by human alveolar macrophages

To determine whether alveolar macrophages from smokers have an abnormal interleukin 1 beta (IL-1) release, we obtained macrophages by bronchoalveolar lavage (BAL) of otherwise healthy volunteers in three groups: nonsmokers (NS; n = 11), light smokers (LS, less than 10 pack-yr smoking history; n = 4) and heavy smokers (HS, greater than 10 pack-yr smoking history; n = 9). After 24 h in culture, unstimulated macrophages (from each group) released negligible amounts of IL-1. Lipopolysaccharide (LPS) (1 micrograms/ml) caused release of 21.77 +/- 4.33 ng IL-1/10(6) cells at 24 h from NS macrophages; IL-1 release from HS macrophages was significantly decreased (5.52 +/- 1.66 ng/10(6) cells; P less than 0.05), whereas LS macrophages released intermediate amounts (15.07 +/- 6.15 ng/10(6) cells). Release of IL-1 from HS macrophages was also decreased after 48 and 72 h in culture and was observed over a wide range of concentrations of LPS. The decreased amount of IL-1 in HS macrophage supernatants appeared to be due to a defect in release of IL-1 from the cells and not due to a defect in production of the mediator, since total IL-1 (IL-1 present in the cell lysates plus that in the cell supernatants) was similar in the NS and HS groups. In addition, after 24 h in culture, LPS-stimulated HS macrophages released significantly less prostaglandin E2 (PGE2) (which can suppress IL-1 production) than did NS macrophages; in the presence of indomethacin, which abolished macrophage PGE2 release, no augmentation of LPS-stimulated IL-1 release was observed. Cell viability, as measured by lactate dehydrogenase release, was not different between HS and NS macrophages under any conditions. We conclude that there is a defect in release but not production of IL-1 from the alveolar macrophages of chronic smokers.

Angiotensin II receptors in rabbit renal preglomerular vessels

Controversy exists regarding the specific sites within the renal microcirculation affected by angiotensin II (ANG II). Under some conditions, ANG II can elicit direct vasoconstrictor responses in the preglomerular vessels and efferent arterioles. These experiments were designed to evaluate the binding of 125I-ANG II in preglomerular vessels. Arcuate and interlobular arteries, with attached proximal segments of afferent arterioles, were microdissected from rabbit renal cortexes. A membrane preparation was obtained from the pooled freshly dissected vessels and utilized in an ANG II radioreceptor assay on the same day. Binding site concentrations [N] and dissociation constants [KD] were obtained by Scatchard analyses of binding inhibition data. Specific binding was saturable and reversible. The dissociation of bound ANG II was enhanced in the presence of a nonhydrolyzable analogue of GTP. Linear Scatchard plots were obtained, indicating the presence of a single class of high-affinity binding sites. The KD and N are similar to those for ANG II receptors in extrarenal vascular tissue. The order of binding inhibition potencies of ANG analogues was [Sar1,Ile8]-ANG II much greater than [Sar1,Ala8]ANG II = ANG II = ANG III much greater than ANG I, which is consistent with in vivo observations of the effects of these analogues on renal blood flow. The binding inhibition potencies of ANG III and [Sar1,Ile8]ANG II were greater in renal compared with reported values for extrarenal vasculature and rabbit glomeruli. Furthermore, there were no differences in ANG II receptor parameters in preglomerular vessels obtained from pregnant and nonpregnant rabbits.(ABSTRACT TRUNCATED AT 250 WORDS)

Fibroblast proliferation induced by silica-exposed human alveolar macrophages

Inhalation of silica dust is an important cause of pulmonary fibrosis. In these studies, we demonstrate that supernatants of silica-stimulated human alveolar macrophages cause significantly (p less than 0.05) greater amounts of fibroblast proliferation than do supernatants of macrophages stimulated with optimal amounts of endotoxin (LPS). The amount of fibroblast proliferation was similar (p greater than 0.2) in the presence of supernatants of LPS-stimulated macrophages and supernatants of unstimulated adherent macrophages. When macrophages were stimulated with LPS in the presence of indomethacin (to inhibit the cyclooxygenase pathway of arachidonic acid), the supernatants stimulated the same amount of proliferation of fibroblasts as did supernatants of silica-stimulated macrophages. Indomethacin did not increase the growth factor activity of supernatants of silica-stimulated or unstimulated macrophages. Consistent with these observations, supernatants of LPS-stimulated macrophages contained 25.5 +/- 3.8 nM of PGE2, whereas supernatants of silica-stimulated macrophages and unstimulated macrophages contained essentially no PGE2. These findings were confirmed by high performance liquid chromatography. The amounts of PGE2 present in supernatants of LPS-stimulated macrophages were sufficient to cause a 75% reduction in the proliferation of maximally stimulated fibroblasts. These studies suggest that silica may be a very effective stimulus for fibroblast proliferation in vivo since it causes macrophages to release growth factors for fibroblasts without triggering the release of PGE2, an inhibitor of fibroblast proliferation.

In vitro renal eicosanoid production during pregnancy in rabbits

The low renal resistance to blood flow in the presence of an activated endogenous renin-angiotensin system in gravid animals may in part be mediated by the action of eicosanoids produced in situ. To evaluate intrarenal eicosanoid production during gestation in rabbits, we quantitated immunoreactive PGE2, 6-keto-PGF1 alpha (a stable metabolite of PGI2) and thromboxane B2 (a stable metabolite of thromboxane A2) in unextracted media after incubation of renal slices and isolated glomeruli. In cortical slices from nonpregnant and pregnant rabbits, PGE2 production (micrograms.g-1.30 min-1) was 0.04 +/- 0.005 and 0.08 +/- 0.01 (P less than 0.01) and 6 keto-PGF1 alpha was 0.03 +/- 0.01 and 0.06 +/- 0.01 (P less than 0.05), respectively. In papillary slices, PGE2 production was 14 +/- 2 and 21 +/- 2 (P less than 0.05) and 6 keto-PGF1 alpha was 4 +/- 1 and 5 +/- 1 (P greater than 0.05) for nonpregnant and pregnant rabbits, respectively. Thromboxane B2 production was unchanged during pregnancy in both cortex and papilla. Acute captopril administration to nonpregnant and to pregnant rabbits in vivo failed to alter in vitro renal slice eicosanoid production. Isolated glomeruli from nonpregnant and pregnant rabbits synthesized PGE2 at similar rates. Exogenous arachidonic acid increased PGE2 production (P less than 0.05), but angiotensin II had no effect on eicosanoid production in vitro. These data suggest that the net synthesis of vasodilator eicosanoids is enhanced during gestation in rabbits.(ABSTRACT TRUNCATED AT 250 WORDS)

Human alveolar macrophage arachidonic acid metabolism

Metabolites of arachidonic acid are potent modulators of many biological events, and their release from macrophages appears to play an important role in immune and inflammatory processes. In addition, metabolites of the cyclooxygenase or lipoxygenase pathway exhibit distinct biological effects. We used a method to determine if human alveolar macrophages (HAM) could be selectively activated to release products of cyclooxygenase or lipoxygenase pathway of arachidonic acid. HAM obtained by bronchoalveolar lavage from individuals were [3H]arachidonic acid labeled and then stimulated with lipopolysaccharide (LPS) or Ca ionophore A23187. Essentially no arachidonate metabolites were released by unstimulated cells. LPS caused dose- and time-dependent release of arachidonate and only cyclooxygenase products; no lipoxygenase products were detected, even in presence of cyclooxygenase inhibition. Metabolites released in response to LPS included thromboxane B2, prostaglandins D2, F2a, E2, and hydroxyheptadecatrienoic acid. A23187 caused a rapid release of arachidonate and 5-lipoxygenase products, leukotriene B4 and 5-hydroxyeicosatetraenoic acid; no cyclooxygenase inhibition. This demonstrates that HAM are specifically activated to release metabolites derived from cyclooxygenase or lipoxygenase pathway of arachidonic acid. Additionally, shunting down an alternate pathway is not induced by use of inhibitors of either pathway. This suggests alveolar macrophages may enhance or suppress various inflammatory or immune processes in lung, in part, by selective release of various derivatives of arachidonic acid.