Bradykinin-stimulated changes in inositol phosphate mass in renal papillary collecting tubule cells

The effect of bradykinin on changes in the chemical levels of myo-inositol polyphosphates in renal papillary collecting tubules was investigated. Myo-inositol phosphate mass was determined by means of an enzymatic, fluorometric assay. Bradykinin induced increases in myo-inositol mono-, bis-, and trisphosphate which were both time and concentration dependent. Furthermore, the magnitude of the chemical levels of myo-inositol monophosphate formed were unlikely to be accounted for solely by the formation and degradation of myo-inositol trisphosphate. These observations are consistent with the concomitant hydrolysis of phosphatidylinositol and phosphatidylinositol bisphosphate. This study also confirms, in freshly isolated renal tubules, observations regarding bradykinin-induced phosphatidylinositol bisphosphate hydrolysis made previously in radiolabeled cultures.     

Transient receptor potential vanilloid 1, calcitonin gene-related peptide, and substance P mediate nociception in acute pancreatitis

The mechanism of pancreatitis-induced pain is unknown. In other tissues, inflammation activates transient receptor potential vanilloid 1 (TRPV1) on sensory nerves to liberate CGRP and substance P (SP) in peripheral tissues and the dorsal horn to cause neurogenic inflammation and pain, respectively. We evaluated the contribution of TRPV1, CGRP, and SP to pancreatic pain in rats. TRPV1, CGRP, and SP were coexpressed in nerve fibers of the pancreas. Injection of the TRPV1 agonist capsaicin into the pancreatic duct induced endocytosis of the neurokinin 1 receptor in spinal neurons in the dorsal horn (T10), indicative of SP release upon stimulation of pancreatic sensory nerves. Induction of necrotizing pancreatitis by treatment with L-arginine caused a 12-fold increase in the number of spinal neurons expressing the proto-oncogene c-fos in laminae I and II of L1, suggesting activation of nociceptive pathways. L-arginine also caused a threefold increase in spontaneous abdominal contractions detected by electromyography, suggestive of referred pain. Systemic administration of the TRPV1 antagonist capsazepine inhibited c-fos expression by 2.5-fold and abdominal contractions by 4-fold. Intrathecal, but not systemic, administration of antagonists of CGRP (CGRP(8-37)) and SP (SR140333) receptors attenuated c-fos expression in spinal neurons by twofold. Thus necrotizing pancreatitis activates TRPV1 on pancreatic sensory nerves to release SP and CGRP in the dorsal horn, resulting in nociception. Antagonism of TRPV1, SP, and CGRP receptors may suppress pancreatitis pain.     

An estimate of population sizes of burrowing seabirds at the Diego Ramirez archipelago, Chile, using distance sampling and burrow-scoping

The Diego Ramirez Islands lie 60 nautical miles southwest of Cape Horn and are the breeding site for three species of burrowing seabirds: blue petrels (Halobaena caerulea), common diving petrels (Pelecanoides urinatrix) and sooty shearwater (Puffinus griseus). Burrowing seabirds are highly vulnerable to predation by introduced vertebrate pests, and Diego Ramirez is an important breeding site because it is one of a few remaining subantarctic island groups with no introduced predators. Diego Ramirez is the only known breeding site for blue petrels in the southeast Pacific region, holding about 80% of the global population of that species, and with a population ten times larger than any other population in the world. We estimated the population size in 2002, using a novel application of the distance sampling technique to determine burrow density, and a burrow-scope with excavations to determine occupying species. We found that density was correlated with slope angle and soil wetness. Burrow densities in flatter terrain with drier soils were 2.03 burrows/m² (95% confidence intervals: 1.82–2.27) and 1.11 burrows/m² (0.84–1.48) in steeper terrain with wetter soils. The occupation rate of burrows were significantly different between habitat types (t=2.74, d.f. 11, P<0.05); in flatter drier habitats the proportion of burrows that led to a nest was 0.85 (0.74–0.96), in steeper wetter habitats this decreased to 0.64 (0.50–0.78). We used a digital elevation model to calculate true area rather than planar area for the two habitat types on the main island of Bartolome, and charts to calculate planar area for the remainder of the archipelago. There were 1.35 (1.15–1.54) million pairs of blue petrels and 99,000 (65,000–134,000) pairs of common diving petrels on the archipelago. These are similar figures to those from the only previous estimate, made in 1980. We found breeding sooty shearwaters for the first time, and estimated a population of several thousand pairs. We emphasise the facility of distance sampling as an unbiased technique with practical advantages over commonly used area search methods for monitoring populations of burrowing seabirds. These advantages include increased survey efficiency allowing a larger sample size for a given effort and a correspondingly tighter estimation of density.     

AdoHcy hydrolase of Trichomonas vaginalis: studies of the effects of 5'-modified adenosine analogues and related 6-N-cyclopropyl derivatives

Trypanosoma brucei and Trichomonas vaginalis are both parasitic protozoans that are known to share many similar biochemical pathways. Aristeromycin, as well as 5'-iodovinyl and 5'-oxime analogues of adenosine, are potent inhibitors of AdoHcy hydrolase in T. brucei, an enzyme that catalyses the hydrolysis of AdoHcy to adenosine and L-homocysteine. To help determine the role of this enzyme in T. vaginalis, we have tested a library of 5'-modified adenosine derivatives, including 5'-deoxy-5'-(iodomethylene)-adenosine and related 6-N-cyclopropyl analogues. Our results indicate that these inhibitors are effective at inhibiting the growth of T. vaginalis, by as much as 95%.     

Selection on Alleles Affecting Human Longevity and Late-Life Disease: The Example of Apolipoprotein E

It is often claimed that genes affecting health in old age, such as cardiovascular and Alzheimer diseases, are beyond the reach of natural selection. We show in a simulation study based on known genetic (apolipoprotein E) and non-genetic risk factors (gender, diet, smoking, alcohol, exercise) that, because there is a statistical distribution of ages at which these genes exert their influence on morbidity and mortality, the effects of selection are in fact non-negligible. A gradual increase with each generation of the ε2 and ε3 alleles of the gene at the expense of the ε4 allele was predicted from the model. The ε2 allele frequency was found to increase slightly more rapidly than that for ε3, although there was no statistically significant difference between the two. Our result may explain the recent evolutionary history of the epsilon 2, 3 and 4 alleles of the apolipoprotein E gene and has wider relevance for genes affecting human longevity.     

Macroscopic spectral imaging and gene expression analysis of the early stages of melanoma

BACKGROUND: The stages of melanocytic progression are defined as atypical (dysplastic) nevus, melanoma in situ, melanoma in the radial growth phase (RGP), melanoma in the vertical growth phase (VGP), and melanoma in the metastatic growth phase (MGP). Melanoma in situ and RGP melanoma often develop in contiguous association with atypical nevi. This frequently poses a problem with respect to their early detection. Furthermore, unlike cells obtained from VGP and MGP melanomas, cells derived from melanoma in situ and RGP melanoma do not proliferate in vitro. Thus, compared to the late stages of the disease, less information is available regarding genes expressed in the early stages. MATERIALS AND METHODS: To determine whether spectral imaging, a recently developed optical imaging technique, can detect melanoma in situ and RGP melanoma arising in melanoma precursor lesions, atypical nevi in patients with a clinical history of melanoma were subjected to noninvasive macroscopic spectral imaging. To determine at what stage in the progression pathway of melanoma genes having important biological functions in VGP and MGP melanomas are activated and expressed, lesions of melanoma in situ were analyzed by immunohistochemistry and in situ hybridization for expression of some of these known molecular and immunologic markers. RESULTS: The present study demonstrates the capability of noninvasive spectral imaging to detect melanoma in situ and RGP melanoma that arise in contiguous association with atypical nevi. Furthermore, the study provides evidence that genes and antigens expressed in VGP and MGP melanoma are also expressed in melanoma in situ. CONCLUSIONS: Because of the dark and variegated pigmentation of atypical nevi, melanoma in situ and RGP melanoma that arise in these melanoma precursor lesions are often difficult to recognize and thus frequently go unnoticed. The application of new optical screening techniques for early detection of melanoma and the identification of genes expressed in the early stages of melanoma development are two important avenues in the pursuit of melanoma prevention. The investigations presented here document that macroscopic spectral imaging has the potential to detect melanoma in its early stage of development and that genes essential for the proliferation and cell adhesion of VGP and MGP melanoma are already expressed in melanoma in situ.     

Poly(ADP-ribose) polymerase-1 is a survival factor for radiation-exposed intestinal epithelial stem cells in vivo

Poly(ADP-ribose) polymerase-1 (PARP-1) is a key enzyme mediating the cellular response to DNA strand breaks. It plays a critical role in genomic stability and survival of proliferating cells in culture undergoing DNA damage. Intestinal epithelium is the most proliferative tissue in the mammalian body and its stem cells show extreme sensitivity to low-level genotoxic stress. We investigated the role of PARP-1 in the in vivo damage response of intestinal stem cells in crypts of PARP-1^–/– and control mice following whole-body γ-irradiation (1 Gy). In the PARP-1^–/– mice there was a significant delay during the first 6 h in the transient p53 accumulation in stem cells whereas an increased number of cells were positive for p21^CIP1/WAF1. Either no or only marginal differences were noted in MDM2 expression, apoptosis, induction of or recovery from mitotic blockage, or inhibition of DNA synthesis. We further observed a dose-dependent reduction in crypt survival measured at 4 days post-irradiation in control mice, and this crypt-killing effect was significantly potentiated in PARP-1^–/– mice. Our results thus establish that PARP-1 acts as a survival factor for intestinal stem cells in vivo and suggest a functional link with early p53 and p21^CIP1/WAF1 responses.