Infarction alters both the distribution and noradrenergic properties of cardiac sympathetic neurons

Regional changes occur in the sympathetic innervation of the heart after myocardial infarction (MI), including loss of norepinephrine (NE) uptake and depletion of neuronal NE. This apparent denervation is accompanied by increased cardiac NE spillover. One potential explanation for these apparently contradictory findings is that the sympathetic neurons innervating the heart are exposed to environmental stimuli that alter neuronal function. To understand the changes that occur in the innervation of the heart after MI, immunohistochemical, biochemical, and molecular analyses were carried out in the heart and stellate ganglia of control and MI rats. Immunohistochemistry with panneuronal markers revealed extensive denervation in the left ventricle (LV) below the infarct, but sympathetic nerve fibers were retained in the base of the heart. Western blot analysis revealed that tyrosine hydroxylase (TH) expression (normalized to a panneuronal marker) was increased significantly in the base of the heart and in the stellate ganglia but decreased in the LV below the MI. NE transporter (NET) binding sites, normalized to total protein, were unchanged, except in the LV, where [3H]nisoxetine binding was decreased. TH mRNA was increased significantly in the left and right stellate ganglia after MI, while NET mRNA was not. In the base of the heart, increased TH coupled with no change in NET may explain the increase in extracellular NE observed after MI. Coupled with substantial denervation in the LV, these changes likely contribute to the onset of cardiac arrhythmias.     

Lack of Apparent Neurological Abnormalities in Rabbits Sensitized by Gangliosides

Two very high titer polyclonal antibodies against two ganglioside antigens, GM1 and GD1a, have been raised in New Zealand white rabbits using a homogeneous suspension of the highly purified antigens in Keyhole Limpet Hemocyanin and Freunds adjuvant. The antisera were prepared over a period of 6 months with repeated injections of the ganglioside suspension, followed by an intravenous injection of the purified ganglioside solution, and collecting the serum (approximately 50 ml) at defined time intervals. The GM1-antibody, thus prepared, showed a cross reactivity toward GD1b and asialo-GM1 (GA1), while the GD1a-antibody reacted with GD1a, GM1 and GA1 and GD1b as determined by immuno-overlay and ELISA methods. The titer for GM1 antiserum, determined by ELISA, was greater than 1/10,000 dilution while the titer for GD1a antibody was greater than 1/5,000 dilution. No neurological or behavioral abnormality was observed during the period of antiserum production. To evaluate any likely pathological damage caused by such a high titer ganglioside-antibody, autopsy of CNS as well PNS tissues from the rabbits were carried out after the final bleeding. No obvious pathological changes, including demyelination, were noted in any of the four rabbits. These observations cast doubt as to the direct effect of anti-ganglioside antibody induced neurological and pathological disorders.Special issue dedicated to Lawrence F. Eng.     

Detection and characterization of a dehalogenating microorganism by terminal restriction fragment length polymorphism fingerprinting of 16S rRNA in a sulfidogenic, 2-bromophenol-utilizing enrichment

Terminal restriction fragment length polymorphism analysis of reverse-transcribed 16S rRNA during periods of community flux was used as a tool to delineate the roles of the members of a 2-bromophenol-degrading, sulfate-reducing consortium. Starved, washed cultures were amended with 2-bromophenol plus sulfate, 2-bromophenol plus hydrogen, phenol plus sulfate, or phenol with no electron acceptor and were monitored for substrate use. In the presence of sulfate, 2-bromophenol and phenol were completely degraded. In the absence of sulfate, 2-bromophenol was dehalogenated and phenol accumulated. Direct terminal restriction fragment length polymorphism fingerprinting of the 16S rRNA in the various subcultures indicated that phylotype 2BP-48 (a Desulfovibrio-like sequence) was responsible for the dehalogenation of 2-bromophenol. A stable coculture was established which contained predominantly 2BP-48 and a second Desulfovibrio-like bacterium (designated BP212 based on terminal restriction fragment length polymorphism fingerprinting) that was capable of dehalogenating 2-bromophenol to phenol. Strain 2BP-48 in the coculture could couple reductive dehalogenation to growth with 2-bromophenol, 2,6-dibromophenol, or 2-iodophenol and lactate or formate as the electron donor. In addition to halophenols, strain 2BP-48 appears to use sulfate, sulfite, and thiosulfate as electron acceptors and is capable of simultaneous sulfidogenesis and reductive dehalogenation in the presence of sulfate.     

Effect of sex on counterregulatory responses to exercise after antecedent hypoglycemia in type 1 diabetes

A marked sexual dimorphism exists in healthy individuals in the pattern of blunted neuroendocrine and metabolic responses following antecedent stress. It is unknown whether significant sex-related counterregulatory differences occur during prolonged moderate exercise after antecedent hypoglycemia in type 1 diabetes mellitus (T1DM). Fourteen patients with T1DM (7 women and 7 men) were studied during 90 min of euglycemic exercise at 50% maximal O(2) consumption after two 2-h episodes of previous-day euglycemia (5.0 mmol/l) or hypoglycemia of 2.9 mmol/l. Men and women were matched for age, glycemic control, duration of diabetes, and exercise fitness and had no history or evidence of autonomic neuropathy. Exercise was performed during constant "basal" intravenous infusion of regular insulin (1 U/h) and a 20% dextrose infusion, as needed to maintain euglycemia. Plasma glucose and insulin levels were equivalent in men and women during all exercise and glucose clamp studies. Antecedent hypoglycemia produced a relatively greater (P < 0.05) reduction of glucagon, epinephrine, norepinephrine, growth hormone, and metabolic (glucose kinetics) responses in men compared with women during next-day exercise. After antecedent hypoglycemia, endogenous glucose production (EGP) was significantly reduced in men only, paralleling a reduction in the glucagon-to-insulin ratio and catecholamine responses. In conclusion, a marked sexual dimorphism exists in a wide spectrum of blunted counterregulatory responses to exercise in T1DM after prior hypoglycemia. Key neuroendocrine (glucagon, catecholamines) and metabolic (EGP) homeostatic responses were better preserved during exercise in T1DM women after antecedent hypoglycemia. Preserved counterregulatory responses during exercise in T1DM women may confer greater protection against hypoglycemia than in men with T1DM.     

Effects of FGF9 on embryonic Sertoli cell proliferation and testicular cord formation in the mouse

Proliferation and cord formation by embryonic Sertoli cells are pivotal events involved in testis morphogenesis. A number of growth factors have been implicated in mediating these events. However, the exact level of involvement and importance of each as yet remains elusive. We have adopted an in vitro approach to assess developing mouse Sertoli cells, whereby they are cultured in the presence or absence of fibroblast growth factor (FGF9) and/or extracellular matrix (ECM) gel, since previous studies have shown that ECM gel aids Sertoli cell differentiation. The present findings corroborate this effect, but in addition demonstrate that in the presence of FGF9 (10 ng/ml), cells undergo greater proliferation than those cultured on gel alone. They also display a differentiated epithelial phenotype, with appositional contact of cell membranes in cord-like aggregations. In addition we have shown that cultured Sertoli cells generally express a smaller truncated, nuclear form of the FGFr3, although in the presence of FGF9 and absence of gel, the larger, cytoplasmic form of the receptor is also expressed. Immunolocalisation of FGFr3 in Sertoli cells of whole testes revealed a temporal expression pattern profile, with high levels being abundant in the embryonic testicular cords and at puberty, but an absence in adult Sertoli cells. Our findings suggest that FGF9 plays an important role in proliferation and organisation of embryonic Sertoli cells during testis morphogenesis.     

High-risk premenopausal women's experiences of undergoing prophylactic oophorectomy: a descriptive study

Women who are at increased risk of developing ovarian cancer because of their family history may need to make decisions about the medical management of their cancer risk--whether to have ovarian screening or undergo prophylactic surgery. This qualitative study explores the perceived physical and emotional implications of undergoing preventative surgery using data collected during interviews with 23 high-risk premenopausal women who had undergone prophylactic oophorectomy because of their family history of cancer. Despite the fact that all of these women regarded their decision to undergo surgery extremely positively, 20 women also described what they regarded as the costs of undergoing surgery. These included post-operative complications, the onset of menopausal symptoms, side effects of hormone replacement therapy, and negative effects on body image and gender identity. The perceived benefits of surgery were described as risk reduction, enabling one to fulfil family obligations, removing the need for gynecological screening, cessation of menstruation, and positive side effects of hormone replacement therapy. This study suggests there is a need to inform women about potential physical and emotional sequelae of oophorectomy prior to undergoing this procedure.     

Consent, commodification and benefit-sharing in genetic research

The global value of the biotechnology industry is now estimated at 17 billion dollars, with over 1300 firms involved as of the year 2000. ^{2 2} Holland, S . Contested Commodities at Both Ends of Life: Buying and Selling Gametes, Embryos and Body Tissues . Kennedy Institute of Ethics Journal 2001 ; 11 : 263 – 284 .
It has been said that ‘What we are witnessing is nothing less than a new kind of gold rush, and the territory is the body.’ As in previous gold rushes, prospectors are flooding into unexplored and ‘wide open’ territories from all over the world, with possible ramifications for exploitation of Third World populations. These territories are also the Wild West of bioethics insofar as the law has very little hold on them: existing medical and patent law, such as the Moore and Chakrabarty cases, exert little control over powerful economic interests in both the United States and Europe. In the absence of a unified and consistent law on property in the body, the focus is increasingly on refining the consent approach to rights in human tissue and the human genome, with sensitive and promising developments from the Human Genetics Commission and the Department for International Development consultation on intellectual property. These developments incorporate the views of vulnerable genetic communities such as Native Americans or some Third World populations, and should be welcomed because they recognise the power imbalance between such groups and First World researchers or firms. However, they also highlight the continued tension about what is really wrong with commodifying human tissue or the human genome. Where’s the injustice, and can it be solved by a more sophisticated consent procedure?     

Natal homing in juvenile loggerhead turtles (Caretta caretta)

Juvenile loggerhead turtles (Caretta caretta) from West Atlantic nesting beaches occupy oceanic (pelagic) habitats in the eastern Atlantic and Mediterranean, whereas larger juvenile turtles occupy shallow (neritic) habitats along the continental coastline of North America. Hence the switch from oceanic to neritic stage can involve a trans-oceanic migration. Several researchers have suggested that at the end of the oceanic phase, juveniles are homing to feeding habitats in the vicinity of their natal rookery. To test the hypothesis of juvenile homing behaviour, we surveyed 10 juvenile feeding zones across the eastern USA with mitochondrial DNA control region sequences (N = 1437) and compared these samples to potential source (nesting) populations in the Atlantic Ocean and Mediterranean Sea (N = 465). The results indicated a shallow, but significant, population structure of neritic juveniles (PhiST = 0.0088, P = 0.016), and haplotype frequency differences were significantly correlated between coastal feeding populations and adjacent nesting populations (Mantel test R2 = 0.52, P = 0.001). Mixed stock analyses (using a Bayesian algorithm) indicated that juveniles occurred at elevated frequency in the vicinity of their natal rookery. Hence, all lines of evidence supported the hypothesis of juvenile homing in loggerhead turtles. While not as precise as the homing of breeding adults, this behaviour nonetheless places juvenile turtles in the vicinity of their natal nesting colonies. Some of the coastal hazards that affect declining nesting populations may also affect the next generation of turtles feeding in nearby habitats.     

Heparin affects signaling pathways stimulated by fibroblast growth factor-1 and -2 in type II cells

Undersulfation of the basement membrane matrix of alveolar type II (AT2) cells compared with that of neighboring type I cells is believed to account for some of the known morphological and functional differences between these pneumocytes. Heparin, a model for sulfated components of basement membrane matrices, is known to inhibit fibroblast growth factor (FGF)-2-stimulated DNA synthesis as well as gene expression of FGF-2 and its receptor in AT2 cells. To determine whether these end points result from specific effects of heparin on FGF-related signaling pathways, isolated rat AT2 cells were treated with 100 ng/ml FGF-1 or FGF-2 in the presence of up to 500 microg/ml heparin. In addition, experiments were done on cells grown in the presence of 20 mM sodium chlorate (sulfation inhibitor). High-dose heparin reduced FGF-1- or FGF-2-stimulated phosphorylation of mitogen-activated protein kinase kinases (MEK1/2), p44/42 mitogen-activated protein kinases (MAPK/ERK1/2), stress-activated protein kinase/c-Jun NH(2)-terminal kinase, Akt/protein kinase B, and p90(RSK). FGF-2-stimulated signaling was more sensitive to heparin's effects than was signaling stimulated by FGF-1. Heparin had an additive effect on the reduced [(3)H]thymidine incorporation in FGF-2-treated AT2 cells caused by inhibition of the MEK/ERK pathway by the MEK inhibitor PD-98059. The data suggest that heparin's known capacity to alter DNA synthesis and, possibly, other biological end points is realized via cross talk between multiple signaling pathways.