Scaling ADLs within the MDS

BACKGROUND

Dependency in activities of daily living (ADLs) is a reality within nursing homes, and we describe ADL measurement strategies based on items in the Minimum Data Set (MDS) and the creation and distributional properties of three ADL self-performance scales and their relationship to other measures.

METHODS

Information drawn from four data sets for a multistep analysis was guided by four study objectives: (1) to identify the subcomponents of ADLs that are present in the MDS battery; (2) to demonstrate how these items could be aggregated within hierarchical and additive ADL summary scales; (3) to describe the baseline and longitudinal distributional properties of these scales in a large, seven-state MDS database; and (4) to evaluate how these scales relate to two external criteria.

RESULTS

Prevalence and factor structure findings for seven MDS ADL self-performance variables suggest that these items can be placed into early, middle, and late loss ADL components. Two types of summary ADL self-performance measures were created: additive and hierarchical. Distributional properties of these scales are described, as is their relationship to two external ADL criteria that have been reported in prior studies: first as an independent variable predicting staff time involved in resident care; second as a dependent variable in a study of the efficacy of two programs to improve resident functioning.

CONCLUSIONS

The new ADL summary scales, based on readily available MDS data, should prove useful to clinicians, program auditors, and researchers who use the MDS functional self-performance items to determine a resident's ADL status.

Clathrin-coated vesicles in nervous tissue are involved primarily in synaptic vesicle recycling

The recycling of synaptic vesicles in nerve terminals is thought to involve clathrin-coated vesicles. However, the properties of nerve terminal coated vesicles have not been characterized. Starting from a preparation of purified nerve terminals obtained from rat brain, we isolated clathrin-coated vesicles by a series of differential and density gradient centrifugation steps. The enrichment of coated vesicles during fractionation was monitored by EM. The final fraction consisted of greater than 90% of coated vesicles, with only negligible contamination by synaptic vesicles. Control experiments revealed that the contribution by coated vesicles derived from the axo-dendritic region or from nonneuronal cells is minimal. The membrane composition of nerve terminal-derived coated vesicles was very similar to that of synaptic vesicles, containing the membrane proteins synaptophysin, synaptotagmin, p29, synaptobrevin and the 116-kD subunit of the vacuolar proton pump, in similar stoichiometric ratios. The small GTP-binding protein rab3A was absent, probably reflecting its dissociation from synaptic vesicles during endocytosis. Immunogold EM revealed that virtually all coated vesicles carried synaptic vesicle proteins, demonstrating that the contribution by coated vesicles derived from other membrane traffic pathways is negligible. Coated vesicles isolated from the whole brain exhibited a similar composition, most of them carrying synaptic vesicle proteins. This indicates that in nervous tissue, coated vesicles function predominantly in the synaptic vesicle pathway. Nerve terminal-derived coated vesicles contained AP-2 adaptor complexes, which is in agreement with their plasmalemmal origin. Furthermore, the neuron-specific coat proteins AP 180 and auxilin, as well as the alpha a1 and alpha c1-adaptins, were enriched in this fraction, suggesting a function for these coat proteins in synaptic vesicle recycling.

Chagas' disease

Chagas' disease, caused by Trypanosoma cruzi, is an important cause of morbidity in many countries in Latin America. The important modes of transmission are by the bite of the reduviid bug and blood transfusion. The organism exists in three morphological forms: trypomastigotes, amastigotes, and epimastigotes. The mechanism of transformation and differentiation is currently being explored, and signal transduction pathways of the parasites may be involved in this process. Parasite adherence to and invasion of host cells is a complex process involving complement, phospholipase, penetrin, neuraminidase, and hemolysin. Two clinical forms of the disease are recognized, acute and chronic. During the acute stage pathological damage is related to the presence of the parasite, whereas in the chronic stage few parasites are found. In recent years the roles of tumor necrosis factor, gamma interferon, and the interleukins in the pathogenesis of this infection have been reported. The common manifestations of chronic cardiomyopathy are arrhythmias and thromboembolic events. Autoimmune, neurogenic, and microvascular factors may be important in the pathogenesis of the cardiomyopathy. The gastrointestinal tract is another important target, and "mega syndromes" are common manifestations. The diagnosis and treatment of this infection are active areas of investigation. New serological and molecular biological techniques have improved the diagnosis of chronic infection. Exacerbations of T. cruzi infection have been reported for patients receiving immuno-suppressive therapy and for those with AIDS.

A characterisation of long-term depression induced by metabotropic glutamate receptor activation in the rat hippocampus in vitro

1. In the CA1 region of hippocampal slices prepared from juvenile (12- to 18-day-old) rats, activation of group I metabotropic L-glutamate (mGlu) receptors by the specific agonist (RS)-3,5-dihydroxyphenylglycine (DHPG) induces a form of long-term depression (LTD) of excitatory synaptic transmission. 2. We have used a variety of electrophysiological techniques applied to CA1 neurones in hippocampal slices and from pyramidal cells in dissociated hippocampal cultures to investigate the Ca2+ dependence and locus of expression of DHPG-induced LTD. 3. In patch-clamp experiments from hippocampal slices, bath application of DHPG induced a depression of synaptically evoked responses that persisted for the duration of the recording (up to 2 h after commencing washout of DHPG) in 27 of 29 neurones investigated. 4. DHPG-induced LTD was associated with an increase in both the paired-pulse facilitation ratio and the coefficient of variation of EPSCs. 5. Using dendritic recording, there was a decrease in EPSC success rate (number of trials that elicited a detectable response) but no change in potency (mean EPSC amplitude excluding failures) associated with DHPG-induced LTD. 6. In experiments using dissociated hippocampal cultures, application of DHPG elicited a persistent decrease in the frequency of tetrodotoxin-resistant miniature EPSCs but no change in the amplitude of such events. 7. DHPG-induced LTD was not blocked by intracellular application of the calcium chelator BAPTA. It was also unaffected when intracellular calcium stores were depleted by perfusion with thapsigargin. Furthermore, when synaptic transmission was blocked by perfusing with Ca2+-free medium, DHPG application reliably induced LTD. 8. These data suggest that DHPG-induced LTD is Ca2+ independent and is expressed presynaptically.

Hypoxia-induced increased permeability of endothelial monolayers occurs through lowering of cellular cAMP levels

Prolonged exposure to hypoxia, as at high altitude, results in increased vascular permeability that may be ameliorated by administration of glucocorticoids. To understand mechanisms underlying these observations, cultured bovine aortic and pulmonary artery endothelial cells (ECs) were subjected to hypoxia, and changes in monolayer permeability and adenosine 3',5'-cyclic monophosphate (cAMP) levels were assessed. Exposure of both types of cultured ECs to hypoxia (PO2 approximately 14 Torr) led to a time- and dose-dependent increase in monolayer permeability, as measured by diffusion of radiolabeled solutes, which was associated with a progressive decrease in EC cAMP levels from 60 to 15 pmol/mg protein, and a decrease in EC adenylate cyclase activity. The change in endothelial barrier function was prevented by addition of cAMP analogues. Pertussis toxin protected EC monolayers from hypoxia-mediated increase in permeability while maintaining cAMP levels and adenylate cyclase activity. Addition of dexamethasone to EC monolayers before or simultaneously with their incubation under hypoxic conditions blocked the hypoxia-mediated increase in monolayer permeability. Dexamethasone pretreatment also prevented the decline in cAMP and adenylate cyclase levels in oxygen-deprived cultures. These data indicate that hypoxia decreases EC barrier function by lowering adenylate cyclase activity and cellular cAMP levels. They suggest that dexamethasone may exert its protective effect, in part, by preventing the hypoxia-induced decline in adenylate cyclase activity, leading to an increase in cellular cAMP and maintenance of EC barrier function.

Pathophysiological insights into the cardiomyopathy of Chagas' disease

The evidence gained from both human and animal studies of chronic chagasic cardiomyopathy suggests that the disease occurs as a consequence of several discrete and progressive pathophysiological processes occurring after infection, the ultimate expression of which depends on a host of unidentified factors. Collectively, the infection-associated events compromise microvasculature function and result in hypoperfusion, with consequences indistinguishable from those observed in other, nonparasitological cardiomyopathic diseases secondary to hypoperfusion. Therefore, chronic chagasic cardiomyopathy may share similar pathophysiological abnormalities with other chronic congestive cardiomyopathic states.

Expression of cardiac cytokines and inducible form of nitric oxide synthase (NOS2) in Trypanosoma cruzi-infected mice

Expression of Cardiac Cytokines and Inducible Form of Nitric Oxide Synthase (NOS2) in Trypanosoma cruzi-infected Mice. Journal of Molecular and Cellular Cardiology (1999) 31, 75-88. Both cardiac cytokine and inducible nitric oxide synthase (NOS2) expression have been implicated in the cardiac dysfunction associated with myocarditis and cardiomyopathy. Chagas' disease, caused by Trypanosoma cruzi, is an important cause of cardiomyopathy. We examined the effect of T. cruzi (Brazil strain) infection with or without verapamil treatment on the expression of cytokines and NOS2 in the heart. Messenger RNA for NOS2, IL-1beta, and TNF-alpha was induced in the myocardium of infected mice, and Western blot analysis as well as immunohistochemistry demonstrated a significant increase in NOS2 protein. Verapamil treatment reduced the expression of cardiac NOS2 protein and the mRNAs for NOS2, TNF-alpha, and IL-1beta. Infection-associated increases in cardiac L-citrulline were also reduced by verapamil treatment. Verapamil-treated infected mice that survived for 80 days exhibited less inflammation and fibrosis compared to untreated mice. Gated MRI and echocardiography revealed an increased right ventricular inner diameter (RVID) in untreated but not in verapamil-treated infected CD1 mice. This suggests that the infection-associated expression of cytokines and NOS2 in the heart correlate with the severity of myocarditis and the effect of verapamil. The RVID was significantly increased in infected wild-type (WT) compared to infected syngeneic NOS2 knockout (NOS2-/-) mice. Fractional shortening was decreased and myocardial L-citrulline was increased in infected WT mice. These data suggest that NO generated from cardiac NOS2 may participate in the pathogenesis of murine chagasic heart disease.

Ca2+-independent inhibition of inositol trisphosphate receptors by calmodulin: redistribution of calmodulin as a possible means of regulating Ca2+ mobilization

The interactions between calmodulin, inositol 1,4,5-trisphosphate (InsP3), and pure cerebellar InsP3 receptors were characterized by using a scintillation proximity assay. In the absence of Ca2+, 125I-labeled calmodulin reversibly bound to multiple sites on InsP3 receptors and Ca2+ increased the binding by 190% +/- 10%; the half-maximal effect occurred when the Ca2+ concentration was 184 +/- 14 nM. In the absence of Ca2+, calmodulin caused a reversible, concentration-dependent (IC50 = 3.1 +/- 0.2 microM) inhibition of [3H]InsP3 binding by decreasing the affinity of the receptor for InsP3. This effect was similar at all Ca2+ concentrations, indicating that the site through which calmodulin inhibits InsP3 binding has similar affinities for calmodulin and Ca2+-calmodulin. Calmodulin (10 microM) inhibited the Ca2+ release from cerebellar microsomes evoked by submaximal, but not by maximal, concentrations of InsP3. Tonic inhibition of InsP3 receptors by the high concentrations of calmodulin within cerebellar Purkinje cells may account for their relative insensitivity to InsP3 and limit spontaneous activation of InsP3 receptors in the dendritic spines. Inhibition of InsP3 receptors by calmodulin at all cytosolic Ca2+ concentrations, together with the known redistribution of neuronal calmodulin evoked by protein kinases and Ca2+, suggests that calmodulin may also allow both feedback control of InsP3 receptors and integration of inputs from other signaling pathways.

Enhanced platelet adherence and aggregation in Chagas' disease: a potential pathogenic mechanism for cardiomyopathy

Spasm and thrombosis of the coronary microcirculation has been implicated in the pathogenesis of the cardiomyopathy of Chagas' disease. We demonstrate that increases in platelet adherence and aggregation accompany Trypanosoma cruzi infection and may contribute to the observed microvascular pathology. Scanning electron microscopy and radiolabeled platelets studies revealed that platelet adherence to T. cruzi-infected human endothelial cells was significantly increased when compared to controls (P = 0.024). In in vitro experiments, we determined the influence of infection on prostacyclin production, a marker of endothelial cell perturbation. The basal levels of 6-keto-prostaglandin F1 alpha was significantly greater in the supernatant of infected endothelial cells than in those of uninfected endothelial cells (P less than 0.05). The influence of infection was assessed on platelet aggregation at days 5 and 12 post-infection in A/J mice. Platelets from T. cruzi-infected mice were 2-6-fold more sensitive to aggregation induced by adenosine diphosphate and sodium arachidonate than controls. Thromboxane B2 levels in the plasma of infected mice were greater than controls. These data support the hypothesis that heightened platelet reactivity and endothelial cell dysfunction are associated with acute Chagas' disease and may cause coronary microvascular spasm and/or occlusion.

Direct coupling of opioid receptors to both stimulatory and inhibitory guanine nucleotide-binding proteins in F-11 neuroblastoma-sensory neuron hybrid cells

Evidence is presented for linkage of opioid receptors directly to the stimulatory G protein (guanine nucleotide-binding protein), Gs, in addition to the generally accepted linkage to the inhibitory and "other" G proteins, gi and Go, in F-11 (neuroblastoma-dorsal root ganglion neuron) hybrid cells. Treatment of intact F-11 cells with cholera toxin decreased specific binding of the opioid agonist [D-Ala2,D-Leu5]enkephalin to F-11 cell membranes by 35%, with the remaining binding retaining high affinity for agonist. Under these conditions cholera toxin influenced the alpha subunit of Gs (Gs alpha) but had no effect on the alpha subunit of Gi/o (Gi/o alpha), based on ADP-ribosylation studies. Pertussis toxin treatment decreased high-affinity opioid agonist binding by about 50%; remaining binding was also of high affinity, even though pertussis toxin had inactivated Gi/o alpha selectively and essentially completely. Simultaneous treatment with both toxins had an additive effect, reducing specific binding by about 80%. While opioid agonists inhibited forskolin-stimulated adenylate cyclase activity of F-11 cells as expected, opioids also stimulated basal adenylate cyclase activity, indicative of interaction with Gs as well as Gi. Cholera toxin treatment attenuated opioid-stimulation of basal adenylate cyclase, whereas pertussis toxin treatment enhanced stimulation. In contrast, inhibition by opioid of forskolin-stimulated activity was attenuated by pertussis toxin but not by cholera toxin. It is concluded that a subset of opioid receptors may be linked directly to Gs and thereby mediate stimulation of adenylate cyclase. This Gs-adenylate cyclase interaction is postulated to be responsible for the novel excitatory electrophysiologic responses to opioids found in our previous studies of sensory neurons and F-11 cells.

Clathrin assembly protein AP180: primary structure, domain organization and identification of a clathrin binding site

Binding of AP180 to clathrin triskelia induces their assembly into 60-70 nm coats. The largest rat brain cDNA clone isolated predicts a molecular weight of 91,430 for AP180. Two cDNA clones have an additional small 57 bp insert. The deduced molecular weight agrees with gel filtration results provided the more chaotropic denaturant 6 M guanidinium thiocyanate is substituted for the weaker guanidinium chloride. The sequence and the proteolytic cleavage pattern suggest a three domain structure. The N-terminal 300 residues (pI 8.7) harbour a clathrin binding site. An acidic middle domain (pI 3.6, 450 residues), interrupted by an uncharged alanine rich segment of 59 residues, appears to be responsible for the anomalous physical properties of AP180. The C-terminal domain (166 residues) has a pI of 10.4. AP180 mRNA is restricted to neuronal sources. AP180 shows no significant homology to known clathrin binding proteins, but is nearly identical to a mouse phosphoprotein (F1-20). This protein, localized to synaptic termini, has so far been of unknown function.

Verapamil ameliorates clinical, pathologic and biochemical manifestations of experimental chagasic cardiomyopathy in mice

The influence of long-term verapamil administration on the consequences of Trypanosoma cruzi infection in mice was studied with regard to animal mortality, morbidity, myocardial pathologic features and myocardial beta-adrenergic adenylate cyclase activity. Verapamil administration dramatically decreased the mortality rate from 60% to 6% during the 70 day period of infection. Three clinical stages of infection were evident. In the acute stage (17 days after infection with maximal parasitemia), verapamil treatment not only decreased the incidence of myocardial disease (fibrosis and inflammation), but also protected myocardial beta-adrenergic adenylate cyclase activity. In addition, there was no increase in total body weight, which was regarded as an index of right-sided heart failure. In the subacute stage (30 to 60 days after infection), administration of verapamil continued to decrease myocardial disease and preserve beta-adrenergic adenylate cyclase activity. In addition, verapamil ameliorated the morbidity and mortality associated with this stage of infection. The chronic stage of infection was characterized by a decrease in myocardial disease and in beta-adrenergic adenylate cyclase activity. Thus, independent of the state of infection, long-term verapamil treatment enhanced beta-adrenergic adenylate cyclase activity. In addition, verapamil ameliorated the morbidity associated with infection. Although the relation among these various effects of verapamil in the setting of T. cruzi infection remains to be determined, collectively the results suggested that verapamil administration attenuated the consequences of T. cruzi infection.

Myocardial expression of endothelin-1 in murine Trypanosoma cruzi infection

Chagas' disease, caused by Trypanosoma cruzi, is an important cause of myocarditis and chronic cardiomyopathy and is accompanied by microvascular spasm and myocardial ischemia. We reported previously that infection of cultured endothelial cells with T. cruzi increased the synthesis of biologically active endothlein-1 (ET-1). In the present study, we examined the role of ET-1 in the cardiovascular system of CD1 mice infected with the Brazil strain of T. cruzi and C57BL/6 mice infected with the Tulahuen strain during acute infection. In the myocardium of infected mice myonecrosis and multiple pseudocysts were observed. There was also an intense vasculitis of the aorta, coronary artery, smaller myocardial vessels and the endocardial endothelium. Immunohistochemistry studies employing anti-ET-1 antibody revealed increased expression of ET-1 that was most intense in the endocardial and vascular endothelium. Elevated levels of mRNA for preproET-1, endothelin converting enzyme and ET-1 were observed in the same myocardial samples. Plasma ET-1 levels were significantly elevated in infected CD1 mice 10-15 days post infection. These observations suggest that increased levels of ET-1 are a consequence of the initial invasion of the cardiovascular system and provide a mechanism for infection-associated myocardial dysfunction.

Cancellous and cortical bone architecture and turnover at the iliac crest of postmenopausal osteoporotic women treated with parathyroid hormone 1-84

Treatment with parathyroid hormone [PTH(1-84)] increases lumbar spine bone mineral density and decreases vertebral fractures, but its effects on bone microarchitecture are unknown. We obtained iliac crest biopsies from postmenopausal osteoporotic women given placebo (n=8) or 100 microg PTH(1-84) for 18 (n=8) or 24 (n=7) months to assess cancellous and cortical bone formation and structure. At 18 months, cancellous bone volume (BV/TV) measured by microcomputed tomography and histomorphometry was 45-48% higher in subjects treated with PTH(1-84) versus placebo, a result of higher trabecular number (Tb.N) and thickness. The higher Tb.N appeared to result from intratrabecular tunneling. Connectivity density was higher and structure model index was lower, indicating a better connected and more plate-like trabecular architecture. Cancellous bone formation rate (BFR) was 2-fold higher in PTH(1-84)-treated subjects, primarily because of greater mineralizing surface. Osteoblast and osteoid surfaces were a nonsignificant 58% and 35%, respectively, higher with PTH(1-84) treatment. Osteoclast and eroded surface were unaffected by PTH(1-84). There were no effects of PTH(1-84) treatment on cortical thickness, or endocortical or periosteal BFR, but cortical porosity tended to be higher. Although cancellous BFR was lower at 24 than at 18 months, measures of cancellous and cortical bone structure were similar at both timepoints. The bone produced by PTH(1-84) had normal lamellar structure and mineralization with no abnormal histology. In conclusion, when compared with placebo, treatment of osteoporotic women with PTH(1-84) was associated with higher BV/TV and trabecular connectivity, with a more plate-like architecture, all consistent with the lower vertebral fracture incidence.

Disrupted nitric oxide signaling due to GUCY1A3 mutations increases risk for moyamoya disease, achalasia and hypertension

Moyamoya disease (MMD) is a progressive vasculopathy characterized by occlusion of the terminal portion of the internal carotid arteries and its branches, and the formation of compensatory moyamoya collateral vessels. Homozygous mutations in GUCY1A3 have been reported as a cause of MMD and achalasia. Probands (n = 96) from unrelated families underwent sequencing of GUCY1A3. Functional studies were performed to confirm the pathogenicity of identified GUCY1A3 variants. Two affected individuals from the unrelated families were found to have compound heterozygous mutations in GUCY1A3. MM041 was diagnosed with achalasia at 4 years of age, hypertension and MMD at 18 years of age. MM149 was diagnosed with MMD and hypertension at the age of 20 months. Both individuals carry one allele that is predicted to lead to haploinsufficiency and a second allele that is predicted to produce a mutated protein. Biochemical studies of one of these alleles, GUCY1A3 Cys517Tyr, showed that the mutant protein (a subunit of soluble guanylate cyclase) has a significantly blunted signaling response with exposure to nitric oxide (NO). GUCY1A3 missense and haploinsufficiency mutations disrupt NO signaling leading to MMD and hypertension, with or without achalasia.

Similar withdrawal severity in adolescents and adults in a rat model of alcohol dependence

Alcohol use during adolescence leads to increased risk of developing an alcohol use disorder (AUD) during adulthood. Converging evidence suggests that this period of enhanced vulnerability for developing an AUD may be due to the adolescent's unique sensitivity and response to alcohol. Adolescent rats have been shown to be less sensitive to alcohol intoxication and withdrawal susceptibility; however, age differences in ethanol pharmacokinetics may underlie these effects. Therefore, this study investigated alcohol intoxication behavior and withdrawal severity using a modified Majchrowicz model of alcohol dependence that has been shown to result in similar blood ethanol concentrations (BECs) despite age differences. Adolescent (postnatal day, PND, 35) and adult rats (PND 70+) received ethanol according to this 4-day binge paradigm and were observed for withdrawal behavior for 17h. As expected, adolescents showed decreased sensitivity to alcohol-induced CNS depression as evidenced by significantly lower intoxication scores. Thus, adolescents received significantly more ethanol each day (12.3+/-0.1g/kg/day) than adults (9.2+/-0.2g/kg/day). Despite greater ethanol dosing in adolescent rats, both adolescent and adult groups had comparable peak BECs (344.5+/-10.2 and 338.5+/-7.8mg/dL, respectively). Strikingly, withdrawal severity was similar quantitatively and qualitatively between adolescent and adult rats. Further, this is the first time that withdrawal behavior has been reported for adolescent rats using this model of alcohol dependence. A second experiment confirmed the similarity in BECs at various time points across the binge. These results demonstrate that after consideration of ethanol pharmacokinetics between adults and adolescents by using a model that produces similar BECs, withdrawal severity is nearly identical. This study, in combination with previous reports on ethanol withdrawal in adolescents and adults, suggests only a BEC-dependent effect of ethanol on withdrawal severity regardless of age.

The outcome following fixation of bicondylar tibial plateau fractures

Unstable bicondylar tibial plateau fractures are rare and there is little guidance in the literature as to the best form of treatment. We examined the short- to medium-term outcome of this injury in a consecutive series of patients presenting to two trauma centres. Between December 2005 and May 2010, a total of 55 fractures in 54 patients were treated by fixation, 34 with peri-articular locking plates and 21 with limited access direct internal fixation in combination with circular external fixation using a Taylor Spatial Frame (TSF). At a minimum of one year post-operatively, patient-reported outcome measures including the WOMAC index and SF-36 scores showed functional deficits, although there was no significant difference between the two forms of treatment. Despite low outcome scores, patients were generally satisfied with the outcome. We achieved good clinical and radiological outcomes, with low rates of complication. In total, only three patients (5%) had collapse of the joint of > 4 mm, and metaphysis to diaphysis angulation of 75º, and five patients (9%) with displacement of > 4 mm. All patients in our study went on to achieve full union. This study highlights the serious nature of this injury and generally poor patient-reported outcome measures following surgery, despite treatment by experienced surgeons using modern surgical techniques. Our findings suggest that treatment of complex bicondylar tibial plateau fractures with either a locking plate or a TSF gives similar clinical and radiological outcomes.

Evidence that forskolin activates turkey erythrocyte adenylate cyclase through a noncatalytic site

The diterpene forskolin has been reported to activate adenylate cyclase in a manner consistent with an interaction at the catalytic unit. However, some of its actions are more consistent with an interaction at the coupling unit that links the hormone receptor to the adenylate cyclase activity. This report adds support to the latter possibility. Under conditions that lead to stimulation of adenylate cyclase in turkey erythrocyte membranes by GTP, forskolin also becomes more active. Additional evidence to support an influence of forskolin upon adenylate cyclase via the GTP-coupling protein N includes the following: (i) forskolin, at submaximal concentrations, leads to enhanced sensitivity and responsiveness of isoproterenol-dependent adenylate cyclase activity in turkey erythrocyte membranes; (ii) under specified conditions, the nucleotide GDP, an inhibitor of the stimulating nucleotide GTP and its analog, guanyl imidodiphosphate (Gpp(NH)p), also markedly inhibits the action of forskolin; (iii) both Gpp(NH)p and forskolin are associated with a decrease in agonist affinity for the beta-adrenergic receptor. However, actions of forskolin in the turkey erythrocyte are not identical to those of GTP: (i) forskolin is never as potent as Gpp(NH)p in activating adenylate cyclase; (ii) the magnitude of synergism between isoproterenol and forskolin is not equal to that observed with isoproterenol and Gpp(NH)p; (iii) at high concentrations, forskolin inhibits antagonist binding to the beta-receptor. Forskolin appears to have several sites of action in the turkey erythrocyte membrane, including an influence upon the adenylate cyclase regulatory protein N.

Alterations in intracellular calcium following infection of human endothelial cells with Trypanosoma cruzi

Trypanosoma cruzi infection in cultured human umbilical vein endothelial cells increased basal cellular calcium levels from 55 to 110 nM, as monitored with the fluorescent probe, fura-2. It also influenced intracellular calcium such that consistently higher total levels were observed in response to bradykinin, angiotensin II and norepinephrine, as compared to similarly treated uninfected cells. However, bradykinin and angiotensin II-dependent increases in calcium, when considered as the absolute increment or fold elevation over basal, were significantly lower in infected endothelial cells. Infection also influenced changes in calcium levels due to agents that operate independently of plasma membrane receptors. In the presence of ionomycin, the magnitude and rate of rise of intracellular calcium were decreased; additionally the calcium peak was delayed and the subsequent decline slowed. Similar to the results with bradykinin and angiotensin II, infection decreased both the increment in and fold stimulation of intracellular calcium in response to ionomycin. In contrast, infection altered only the total calcium stimulated in response to oligomycin; neither the fold stimulation of, nor increment in intracellular calcium was affected. These results indicate that (1) infection by T. cruzi alters calcium homeostasis in endothelial cells under basal and stimulated conditions; (2) both receptor-dependent and receptor-independent mechanisms are affected by infection. The possible contribution of altered calcium homeostasis induced by T. cruzi in the pathogenesis of chagasic cardiomyopathy is considered.

Synaptic vesicle recycling. The Ferrari of endocytosis?

After neurotransmission, neurons internalize and recycle the membrane components of synaptic vesicles remarkably quickly; they may have a 'rebuilt, turbo-charged' endocytic engine to achieve these speeds.

Pilot study of chronic maternal hyperoxygenation and effect on aortic and mitral valve annular dimensions in fetuses with left heart hypoplasia

OBJECTIVE

Acute maternal hyperoxygenation (AMH) results in increased fetal left heart blood flow. Our aim was to perform a pilot study to determine the safety, feasibility and direction and magnitude of effect of chronic maternal hyperoxygenation (CMH) on mitral and aortic valve annular dimensions in fetuses with left heart hypoplasia (LHH) after CMH.

METHODS

Gravidae with fetal LHH were eligible for inclusion in a prospective evaluation of CMH. LHH was defined as: sum of aortic and mitral valve annuli Z-scores < -4.5, arch flow reversal and left-to-right or bidirectional atrial level shunting without hypoplastic left heart syndrome or severe aortic stenosis. Gravidae with an affected fetus and with ≥ 10% increase in aortic/combined cardiac output flow after 10 min of AMH at 8 L/min 100% fraction of inspired oxygen were offered enrollment. Nine gravidae were enrolled from February 2014 to January 2015. The goal therapy was ≥ 8 h daily CMH from enrollment until delivery. Gravidae who were cared for from July 2012 to October 2014 with fetal LHH and no CMH were identified as historical controls (n = 9). Rates of growth in aortic and mitral annuli over the final trimester were compared between groups using longitudinal regression.

RESULTS

There were no significant maternal or fetal complications in the CMH cohort. Mean gestational age at study initiation was 29.6 ± 3.2 weeks for the intervention group and 28.4 ± 1.8 weeks for controls (P = 0.35). Mean relative increase in aortic/combined cardiac output after AMH was 35.3% (range, 18.1-47.9%). Median number of hours per day on CMH therapy was 9.3 (range, 6.5-14.6) and median duration of CMH was 48 (range, 33-84) days. Mean mitral annular growth was 0.19 ± 0.05 mm/week compared with 0.14 ± 0.05 mm/week in CMH vs controls (mean difference 0.05 ± 0.05 mm/week, P = 0.33). Mean aortic annular growth was 0.14 ± 0.03 mm/week compared with 0.13 ± 0.03 mm/week in CMH vs controls (mean difference 0.01 ± 0.03 mm/week, P = 0.75). More than 9 h CMH daily (n = 6) was associated with better growth of the aortic annulus in intervention fetuses (0.16 ± 0.03 vs 0.08 ± 0.02 mm/week, P = 0.014).

CONCLUSIONS

CMH is both safe and feasible for continued research. In this pilot study, the effect estimates of annular growth, using the studied method of delivery and dose of oxygen, were small. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Trypanosoma cruzi induces endothelin release from endothelial cells

The potential role of endothelin-1 (ET-1) in the pathogenesis of focal microvascular spasm, previously implicated in the etiology of Chagas' cardiomyopathy, was investigated. There was an increase in ET-1 in the supernatants of Trypanosoma cruzi--infected human umbilical vein endothelial cells (HUVEC). Infection of HUVEC and vascular smooth muscle cells had no effect on the synthesis of transforming growth factor-beta, which induces ET-1 synthesis. Bioassay studies of isolated rat aortic rings revealed that the increases in ET-1 production were associated with augmented contractile responses, which were significantly attenuated by preincubation with the ETA receptor antagonist, BQ-123. When big ET was incubated with the parasite, there was no conversion of the precursor to the active hormone (ET-1), demonstrating that the parasite did not possess the necessary converting enzyme. These observations suggest the potential importance of ET-1 in the etiology of the microvascular spasm associated with Chagas' disease.