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S A Morris

Publications and source records attributed to S A Morris.

At least 37 records · Page 2Linked to original sources
PubMed1998

A novel AP180-related protein in vesicles that concentrate at acetylcholine receptor clusters.

Monoclonal antibodies were generated to vesicular membranes of clathrin coated vesicles enriched for acetylcholinesterase (AChE). One of these, C172, recognizes vesicles which accumulate in muscle cells around nuclei associated with acetylcholine receptor AChR clusters. Immunoblots of muscle extracts and brain purified clathrin coated vesicles show that C172 recognizes a 100 kd band in muscle, but a 180 kd band in brain. Western blots of purified AP180 protein stained with the two antibodies AP180.1 and C172 displayed the same staining pattern. Tryptic digests probed with peptide antibodies (PS26 and PS27) generated to known sequences of AP180 were used to map the epitope for C172 within the brain AP180 sequence. On immunoblots of digested AP180, all AP180 antibodies and C172 recognized a 100 kd tryptic fragment, however only C172 recognized a smaller 60 kd. Our results suggest that the C172 epitope is located within amino acids 305-598 of the AP180 sequence. Confocal fluorescence microscopy of myoblasts and myotubes stained with the C172 antibody gives a punctate immunofluorescence pattern. Myoblasts stained with C172 revealed a polarized distribution of vesicles distinct from that observed when cells are stained with gamma adaptin antibody which is known to localize to trans Golgi network. Myotubes stained with C172 antibody reveal a linear array of vesicular staining. Quantitative analysis of C172 reactive vesicles revealed a significant increase in number of vesicles present around the nuclei associated with the acetylcholine receptor clusters. These vesicles did not colocalize with the Golgi cisternae. These results indicate that a protein with homology to the neuron-specific coated vesicle protein AP180, is present in muscle cells associated with vesicles showing significant concentration around postsynaptic nuclei present in close proximity to AChR clusters.

Adaptor Proteins, Vesicular Transport↗
PubMed1997

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.

Animals↗
PubMed1997

The effect of LPS on cytokine synthesis and lung neutrophil influx after hepatic ischemia/reperfusion injury in the rat.

OBJECTIVE: To determine if cytokine responses and lung injury induced by intravenous (i.v.) lipopolysaccharide (LPS) at 4 hr were enhanced in rats that had been previously subjected to 30 min of total liver ischemia (Pringle's maneuver) followed by 24 hr or 3 days of reperfusion. BACKGROUND: Many patients with liver trauma require occlusion of hepatic blood flow to control hemorrhage and facilitate repair. A significant number of these patients subsequently develop the systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction (MOD) characterized by the release of cytokines and tissue neutrophil influx. Macrophages, including Kupffer cells, may be activated by ischemic injury and dysregulation of their response to LPS may contribute to the development of SIRS and acute respiratory distress syndrome. METHODS: Adult male Sprague-Dawley rats were randomly divided into six groups: three groups received total hepatic ischemia for 30 min and three groups had a sham procedure. Twenty-four hours or 3 days after hepatic ischemia/reperfusion injury, rats were treated with LPS (5 mg/kg) or saline and monitored for 4 hr. We collected serum, bronchoalveolar lavage (BAL) fluid, and lung tissue. RESULTS: Serum and BAL cytokine concentrations were significantly increased by i.v. LPS; however, hepatic ischemia/reperfusion injury 24 hr or 3 days before iv LPS ameliorated this cytokine response. The LPS-induced pulmonary neutrophil influx and histopathological changes were similar in sham and hepatic ischemia/reperfusion-injured groups. CONCLUSIONS: Hepatic ischemia/reperfusion injury significantly attenuated the serum and BAL cytokine concentrations, but did not change pulmonary neutrophil influx or histopathological alterations in response to i.v. LPS.

Animals↗
PubMed1997

Anesthetic management of patients receiving calculus therapy with a third-generation extracorporeal lithotripsy machine.

We reviewed the anesthetic requirements for satisfactory use of a third-generation electromagnetic-source design for extracorporeal shockwave lithotripsy (SWL). Medical records were reviewed for a period of 9 months on all patients receiving anesthesia care for SWL with and without other urologic procedures. The Modulith SL20 was used on 56 ASA Class I-III patients having 87 SWL treatments. Demographic and anesthetic variables were recorded. Complications documented included dysrhythmias, nausea necessitating treatment, and conversion from sedation to regional or general anesthesia. The majority of procedures (83%) were performed on an outpatient basis. Patients were classified as ASA physical status I (27%), II (63%), or III (10%). Monitored anesthesia care with intravenous sedation was utilized in 93% of cases. Of these cases, 78 involved a combination of intravenous propofol, fentanyl, and midazolam; the remaining 3 involved propofol, alfentanil, and/or midazolam. The mean treatment duration was 36 minutes. Patients were discharged within 1 hour after procedure completion in 77 cases (89%). Nausea necessitating treatment was rare (3%). The mean dose of propofol administered with SWL as the only procedure was 272 +/- 112 mg. When SWL was combined with other urologic procedures, the mean dose of propofol was 334 +/- 121 mg. Continuous intravenous propofol infusion provides excellent procedural conditions for SWL on the Modulith SL120, a third-generation lithotripter.

Adult↗
PubMed1997

The effect of specific medical conditions on functional decline.

OBJECTIVES: To examine how functional status among older community-dwelling residents differs over time between those with and those without specific medical conditions. DESIGN: Prospective cohort study. PARTICIPANTS: A total of 1060 community-dwelling Massachusetts residents aged 65 or older who were not totally functionally dependent at baseline assessment. MEASUREMENTS: Functional status, five medical conditions (heart problem, arthritis, diabetes, cancer, and stroke), and the total number of these five medical conditions. Assessments were done at baseline and at two annual follow-ups. RESULTS: Adjusted repeated measures analysis of covariance revealed a time difference (P < .001) for all five medical conditions and group differences for diabetes (P = .006) and stroke (P < .001). Functional abilities declined over time and those with specific medical conditions were more impaired initially, but the rate of decline did not significantly differ from those free of the condition. The presence of each additional medical condition resulted in additional impairment (P < .001), but the rate of decline over time did not differ by number of medical conditions. CONCLUSIONS: Efforts to reduce or prevent the development of specific medical conditions are essential to maintaining functional independence of older people as well as to reducing use of supportive services and admission rates to nursing homes. Particular attention should be directed toward preventing stroke since its consequences are the most functionally disabling.

Activities of Daily Living↗
PubMed1997

Myocardial G proteins in murine Chagas' disease.

G protein alpha subunits and their corresponding mRNA levels were determined in hearts obtained from mice infected with Trypanosoma cruzi, the etiologic agent of Chagas' disease. Protein and mRNA levels of the inhibitory G proteins G alpha i2 and G alpha i3 were increased at 21 and 30 days postinfection (PI). After 60 days, the abundance of protein and corresponding mRNA for G alpha i2 and G alpha i3 were no longer significantly different from uninfected mice. Twenty-one days after infection, G alpha s protein levels decreased markedly, but mRNA for the stimulatory protein did not change. Similar to the Gi proteins, by 60 days differences in G alpha s protein between infected and uninfected mice were no longer evident. There was an increase in the magnitude of G beta subunit protein 21 and 30 days PI as compared with uninfected mice. However, 60 days PI the G beta subunit protein decreased to control levels. The close relationship between the infection-associated increase in G alpha i protein and mRNA suggests that control of protein expression is likely to be exerted at the transcription level. In contrast, control of infection-associated decrease in Gs appears to be at the translational level.

Animals↗
PubMed1996

Cardioprotective actions of verapamil on the beta-adrenergic receptor complex in acute canine Chagas' disease.

UNLABELLED: The effect of verapamil treatment on the myocardial beta-adrenergic adenylyl cyclase complex in acute canine Chagas' disease was investigated. Relative to uninfected animals, 30 days of infection with T. cruzi reduced myocardial adenylyl cyclase activity by over 75%. With continuous verapamil treatment, the infection-associated reduction in adenylyl cyclase activity was less than 50%. The individual components of the beta-adrenergic receptor complex were characterized. INFECTION: (1) increased right ventricular (RV) beta-adrenergic receptor (beta AR) density five-fold; (2) decreased left ventricle beta AR density by 20%; (3) reduced the proportion of high-affinity beta AR receptors to the same extent in both left and right ventricles; (4) reduced alpha s by 50% as determined by Western blot analysis, increased alpha 11-3 but did not change alpha 0; and (5) decreased the magnitude of pertussis-toxin-dependent [32P]ADP ribosylation by 60% as well as the proportion of [32P]ADP-ribose incorporated in alpha 0. Verapamil treatment of infected animals restored RV beta AR receptor density, alpha s and alpha i1-3 to control levels but had no influence on any aspect of pertussis-toxin-dependent [32P]ADP-ribosylation. Verapamil treatment of uninfected animals also: (1) increased beta-adrenergic adenylyl cyclase activity; (2) increased beta AR density in the RV but not the LV; (3) reduced high- to low-affinity beta-adrenergic receptors; and (4) affected only alpha i2 (50% decrease). The results indicate that the major actions of verapamil on the beta-adrenergic adenylyl cyclase complex in acute canine Chagas' disease may help to account for its cardioprotective effects.

Adenylyl Cyclases↗
PubMed1996

Development, testing, and validation of two scales measuring nursing home management of subjects with mental disorder.

This paper describes the development, testing, and validation of summary scales measuring nursing processes commonly used in caring for elderly nursing home residents with cognitive, mood, and behavior problems, or other markers of mental disorder. Data were obtained from a cross-sectional study of 1017 residents from a proportionate random sample in Delaware nursing facilities, to determine the prevalence of mental disorders and to describe distinguishing characteristics and treatments. An exploratory factor analysis was performed on 11 frequently encountered nursing management strategies as applied to 808 subjects with some indicator of mental disorder. Two factors emerged, which were subsequently conceptualized as separate scales (composed of six and five elements, respectively) that measure the basic approaches termed Encouragement and Control. Alpha reliability levels determined internal consistency for each scale. Cognitive, behavioral, and mood correlates were identified for each scale using multiple regression. Replication and validation were achieved when similar findings were obtained using a random sample of 290 residents at Hebrew Rehabilitation Center for Aged, a 725-bed long-term care facility in Boston. LISREL analyses confirmed the presence of at least two dimensions in behavior management strategies. The identification of these approaches is significant in providing non-pharmacologic and non-restraint alternatives to managing elderly residents with symptom distress.

Aged↗
PubMed1996

Substituted glycals as probes of glycosidase mechanisms.

D-Glucal and a series of substituted derivatives have been tested as substrates, inhibitors and inactivators of the Agrobacterium faecalis beta-glucosidase in order to probe structure/function relationships in this enzyme. D-Glucal is shown to be a substrate (kcat = 2.3 min-1, Km = 0.85 mM) undergoing hydration with stereospecific protonation from the alpha-face to yield 2-deoxy-beta-D-glucose. 1-Methyl-D-glucal surprisingly serves as only a poor substrate (kcat = 0.056 min-1, Km = 57 mM), also undergoing protonation from the alpha-face. 2-Fluoro-D-glucal, however is completely inert, as a result of inductive destabilisation of the oxocarbenium ion-like transition state for protonation, and functions only as a relatively weak (Ki = 24 mM) inhibitor. Similar behaviour was seen with almond beta-glucosidase and yeast alpha-glucosidase and for the interaction of 2-fluoro-D-galactal with Escherichia coli beta-galactosidase. A series of of alpha, beta-unsaturated glucal derivatives was also synthesised and tested as potential substrates, inhibitors or inactivators of A. faecalis beta-glucosidase. Of these only 1-nitro-D-glucal functioned as a time dependent, irreversible inactivator (ki = 0.011 min-1, Ki = 5.5 mM), presumably acting as a Michael acceptor. Electrospray mass spectrometric analysis revealed multiple labeling of the enzyme by this inactivator, lessening its usefulness as an affinity label. Less reactive Michael acceptor glycals which might have been more specific (1-cyano-, 2-cyano-, 1-carboxylic acid, 1-carboxylic acid methyl ester) unfortunately did not function as inactivators or substrates, only as relatively weak reversible inhibitors (Ki = 3-96 mM).

Calcium Gluconate↗
PubMed1996

Compromised microcirculation in acute murine Trypanosoma cruzi infection.

Microvascular compromise has been 1 of many factors implicated in the etiology of the cardiomyopathy associated with Chagas' disease. To further assess the effect of Trypanosoma cruzi infection on the microcirculation, we examined the cremaster microvascular model in CD-1 male mice infected with the Brazil strain at 20-25 days postinfection. There was a significant decrease in red cell velocity (Vrbc) in first and third-order arterioles and venules, which was reversed by verapamil treatment. Video recordings revealed a marked inflammatory response that was confirmed by transmission electron microscopy. A marked inflammatory response was not seen in verapamil-treated infected mice. Segmental vasospasm and dilatation was evident in the microvascular bed of infected mice. This was not seen in control or verapamil-treated mice. This model provides a readily accessible method to observe directly the effects of T. cruzi infection on the microcirculatory flow in vivo. In addition, it confirms and extends our previous observations regarding T. cruzi-associated microvascular spasm and underscores a role for verapamil, a calcium-channel blocker, in the amelioration of the Chagas' disease.

Acute Disease↗
PubMed1996

A dynamic model for explaining changes in use of IADL/ADL care in the community.

Evidence exists that support services for community elders vary with need. However, few controlled longitudinal analyses have been carried out regarding descriptive profiles of elders experiencing differential change in service levels -- the focus of analysis here. Using a multivariate profile procedure (PC-Group), 1,730 elders followed over an 18-month period were first classified according to change in functional status groupings that predicted change in hours of service over this period, and each group was subsequently subdivided. Five of nine profiles identified (82% of the sample) were relatively stable functionally. In general, changes in service levels reflected change in functional status; profiles reflected differential change in service level depending upon whether functional status declined; the network provided an unusually high level of service (overextended) at baseline; or the informal network consisted exclusively of children.

Activities of Daily Living↗
PubMed1996

Effects of verapamil on acute murine Chagas' disease.

Continuous administration of verapamil significantly reduced the mortality rate of acute murine Trypanosoma cruzi infection (P < 0.05). The mechanistic basis for these observations was investigated. Verapamil and other calcium-channel blockers did not inhibit the growth of epimastigotes in culture. Furthermore, verapamil did not inhibit the intracellular growth of amastigotes in endothelial cells as determined by the uptake of 3H-uracil. There were no significant differences in parasitemia between infected mice that were untreated and those treated with verapamil. Twenty days postinfection infected, untreated mice had a parasitemia of 5.8 x 10(6) trypomastigotes/ml (SD +/- 2 x 10(6)), whereas infected, verapamil-treated mice had a parasitemia of 2.2 x 10(6) trypomastigotes/ml (SD +/- 0.5 x 10(6)). There was no significant difference in mortality between mice administered verapamil only for the initial 10 days of murine infection compared to those treated continuously. A 3-day delay in the initiation of verapamil administration reduced the mortality rate, but a 10-day delay did not. Propranolol (beta-adrenergic blocker), prazosin (alpha 1-adrenergic blocker), and diltiazem (another calcium-channel blocker) reduced the mortality but not significantly (P = 0.07). In biochemical studies of the beta- adrenergic signal transduction complex, we determined that verapamil and propranolol reversed the infection-associated decrease in myocardial beta- adrenergic adenylyl cyclase activity. In contrast, complementary western blot analysis revealed no significant changes in the G-proteins of the beta- adrenergic receptor complex 45 days postinfection. Therefore, these results suggest that the basis of verapamil's influence on the early critical period of infection is multifactorial and independent of a direct trypanocidal effect.

Acute Disease↗
PubMed1995

Primary structure of the neuronal clathrin-associated protein auxilin and its expression in bacteria.

The protein auxilin is a coat component of brain clathrin-coated vesicles. It interacts directly with the heavy chain of clathrin and supports its assembly into regular cages [Ahle, S. & Ungewickell, E. (1990) J. Cell Biol. 111, 19-29]. The combined open reading frames of three cow brain cDNA clones with a total of 4531 nucleotides predict a molecular mass of 99,504 Da for auxilin. The coding region is followed by a very long untranslated region of at least 1670 nucleotides. By Northern analysis, auxilin transcripts are found only in brain tissue. Auxilin is not related to any of the previously sequenced clathrin-binding proteins, but the region of positions 50-350 is 29% identical (similarity 56%) to the corresponding region of the actin-binding protein tensin from chicken fibroblasts. Recombinant auxilin expressed in and purified from bacteria by affinity chromatography is functional with respect to clathrin binding.

Adaptor Proteins, Vesicular Transport↗
PubMed1995

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.

Animals↗
PubMed1995

Release of guanosine triphosphate binding protein alpha subunits from mouse myocardial membranes: basic properties and their alterations in acute murine Chagas disease.

OBJECTIVE: The aim was to investigate the arrangement of heterotrimeric alpha beta gamma G proteins in myocardial membranes using GTP gamma S dependent release characteristics of their alpha subunits in acute murine Chagas disease. METHODS: The properties of GTP gamma S dependent alpha subunit release were monitored immunochemically as well as by cholera toxin and pertussis toxin catalysed [32P]ADP ribosylation. RESULTS: GTP gamma S, as opposed to other nucleotides, caused optimal and virtually instantaneous release of soluble 40 kDa [32P]ADP ribosylated protein in pertussis toxin treated membranes. When determined immunochemically, infection decreased both the sensitivity to GTP gamma S dependent release of alpha i subunits and appeared to facilitate the appearance of GTP gamma S dependent release of alpha i3. GTP gamma S also caused the release of soluble 45 and 40 kDa proteins as detected by cholera toxin-[32P]ADP ribosylated membranes and immunochemical analysis. With regard to cholera toxin-[32P]ADP ribosylated Gs substrates sensitive to GTP gamma S dependent release, infection (1) decreased the amount of 45 kDa alpha s protein, (2) increased the amount of 40 kDa protein, and (3) enhanced sensitivity to GTP gamma S. In contrast, there was no effect of infection on the magnitude or sensitivity to GTP gamma S dependent release of immunochemical alpha s. CONCLUSIONS: The diverse characteristics of GTP gamma S dependent release of the very similar alpha subunits from myocardial membranes and their unique sensitivity to infection with T cruzi suggest that these very similar proteins are arranged within the plasma membrane in such a manner as to modify their biochemical behaviour.

Adenosine Diphosphate↗