Behavioural and emotional disturbances associated with sleep-disordered breathing symptomatology in children with Down's syndrome

BACKGROUND

Down's syndrome (DS) predisposes to sleep-disordered breathing (SDB). In children with DS, behavioural and emotional disturbances secondary to SDB are often assumed to result from cognitive impairment alone. Our aim was to explore the relationship of behavioural and emotional disturbances with SDB in a population of children with DS.

METHODS

A modified sleep questionnaire, Epworth Sleepiness Scale (ESS), Paediatric ESS and the short form of the developmental behaviour checklist (DBC-P24) were sent to 261 carers of children aged 4 to 15 years with DS in 2012.

RESULTS

Of 120 participants, 25% had probable SDB. In children with probable SDB compared to those without nocturnal symptoms, the total behaviour problem score (TBPS) was significantly higher (20.3 ± 8.6/48 vs. 12 ± 7.5/48; P = 0.002) as was the PaedESS (7.7 ± 5.6/24 vs. 2.8 ± 3.5/24; P = 0.002). For every increase in frequency of choking attacks, snoring and night awakenings, the TBPS increased by 1.37, 1.28 and 1.75 points, respectively, indicating worsening behaviour. The TBPS was found to decrease by 1.31 points for every hour more of self-reported sleep duration (r = -0.25, P = 0.017).

CONCLUSIONS

SDB symptoms and shorter self-reported sleep duration are highly prevalent among children with DS and are independently associated with worsening behaviour using the TBPS.

The soybean-derived peptide lunasin inhibits non-small cell lung cancer cell proliferation by suppressing phosphorylation of the retinoblastoma protein

Lunasin, a soybean bioactive peptide, has both chemopreventive and chemotherapeutic activities. The aim of this study was to determine the chemotherapeutic potential of lunasin against human lung cancer. Treatment of non-small cell lung cancer (NSCLC) cells with highly purified soybean-derived lunasin caused limited, cell-line specific anti-proliferative effects on anchorage-dependent growth whereas two normal bronchial epithelial cell lines were unaffected. Lunasin's antiproliferative effects were potentiated upon utilization of anchorage-independent conditions. Furthermore, NSCLC cell lines that were unaffected by lunasin in anchorage-dependent assays exhibited a dose-dependent inhibition in colony formation or colony size. Mouse xenograft studies revealed that 30 mg lunasin/kg body weight per day decreased NSCLC H1299 tumor volume by 63.0% at day 32. Mechanistic studies using cultured NSCLC H661 cells showed that lunasin inhibited cell cycle progression at the G1/S phase interface without inducing apoptosis. Immunoblot analyses of key cell-cycle proteins demonstrated that lunasin altered the expression of the G1 specific cyclin-dependent kinase complex components, increased levels of p27Kip1, reduced levels of phosphorylated Akt, and ultimately inhibited the sequential phosphorylation of the retinoblastoma protein (RB). These results establish for the first time that lunasin can inhibit NSCLC proliferation by suppressing cell-cycle dependent phosphorylation of RB.

Sensing Small Changes in Protein Abundance: Stimulation of Caco-2 Cells by Human Whey Proteins

Mass spectrometry (MS)-based proteomic approaches have largely facilitated our systemic understanding of cellular processes and biological functions. Cutoffs in protein expression fold changes (FCs) are often arbitrarily determined in MS-based quantification with no demonstrable determination of small magnitude changes in protein expression. Therefore, many biological insights may remain veiled due to high FC cutoffs. Herein, we employ the intestinal epithelial cell (IEC) line Caco-2 as a model system to demonstrate the dynamicity of tandem-mass-tag (TMT) labeling over a range of 5-40% changes in protein abundance, with the variance controls of ± 5% FC for around 95% of TMT ratios when sampling 9-12 biological replicates. We further applied this procedure to examine the temporal proteome of Caco-2 cells upon exposure to human whey proteins (WP). Pathway assessments predict subtle effects due to WP in moderating xenobiotic metabolism, promoting proliferation and various other cellular functions in differentiating enterocyte-like Caco-2 cells. This demonstration of a sensitive MS approach may open up new perspectives in the system-wide exploration of elusive or transient biological effects by facilitating scrutiny of narrow windows of proteome abundance changes. Furthermore, we anticipate this study will encourage more investigations of WP on infant gastrointestinal tract development.

Advantages of laparoscopic resection for ileocolic Crohn’s disease

BACKGROUND

Laparoscopic colorectal procedures are considered to be technically challenging, and there is a lack of consensus regarding the magnitude of their benefits. The laparoscopic approach is generally held to be more expensive. Using a model of a single procedure performed for a single indication (ileocolic resection for Crohn's disease [CD]), we set out to demonstrate the feasibility of this procedure by determining the conversion rate, documenting the patient benefits, and performing a formal cost analysis.

METHODS

Consecutive cases of laparoscopic ileocolic resection for CD were identified (LAP). Case-match methodology identified a series of open laparotomy controls (OPEN) that were matched for five potential confounding criteria: age, gender, diagnosis, type of resection, and date of operation. Pre-, intra-, and postoperative details were gathered. Medical resource utilization was tracked using a standardized database, and all costs were reported in 1999 dollars.

RESULTS

The conversion rate was 5.9%. Resolution of ileus occurred more rapidly in the LAP than in the OPEN group. The time to clears in the LAP group was a median of 0 days (range, 0-4) vs 3.0 days (range, 2-8) in the OPEN group (p = 0.0001). Time to regular diet was 2.0 days (range, 1-6) in the LAP group vs 5.0 days (range, 3-12) in the OPEN group (p = 0.0001). Length of hospital stay was significantly reduced in the LAP group (4.0 days [range, 2-8], vs 7.0 days [range, 3-14], p = 0.0001). The LAP group had significantly lower direct costs ($8684 vs $11,373) and indirect costs ($1358 vs $2349) than the OPEN group (p < 0.001). This resulted in total costs of $9895 for LAP vs $13,268 for OPEN (p < 0.001).

CONCLUSION

Laparoscopic ileocolic resection for CD is feasible. There are significant postoperative benefits in terms of resolution of ileus, narcotic use, and hospital stay. This approach translates into cost savings of >$3300 for laparoscopic patients.

Abstract 3850: Production of recombinant lunasin peptides with enhanced anticancer activity using transient expression in tobacco

Epidemiological observations suggest a correlation between high levels of soybean product consumption and lowered incidence and mortality due to prostate, breast and colon cancer. Lunasin, a 43-44 amino acid peptide derived from soybean, has been implicated as a significant source of this anticancer activity. Lunasin contains nine consecutive aspartic acid residues at the C-terminus that bind to hypoacetlyated core histones, a minimal internal RGD cell adhesion motif and a helical region exhibiting structural homology to conserved sequences of chromatin binding proteins. Initial studies demonstrated that lunasin can prevent the transformation of mammalian cells by chemical carcinogens or viral oncogenes, and inhibits chemically-induced tumors in a mouse skin cancer model. These results suggest that lunasin may be useful as a cancer chemoprevention agent. More recent studies have demonstrated that lunasin can inhibit the proliferation of several established human cancer cell lines in vitro and in vivo, suggesting that lunasin may also be useful as a cancer therapeutic. Lunasin's anticancer effects are currently limited to specific cancer cell types and require 10-100 µM concentrations of peptide. We have now established a transient expression system based on the Tobacco Mosaic Virus vector, Geneware®, for large-scale production of modified forms of recombinant lunasin in tobacco. Our initial studies revealed that we could not detect any significant protein accumulation using constructs expressing lunasin peptides alone. We modified our strategy by expressing lunasin peptides as C-terminal fusions to green fluorescent protein (GFP) that includes a linker sequence containing a thrombin cleavage site. We have demonstrated that this system can produce GFP-lunasin at levels &gt;100 mg/kg fresh weight tissue and demonstrated that the lunasin peptide can be recovered by proteolytic cleavage with thrombin. We have used this system to produce a modified form of lunasin that contains an N-terminal RGD domain sequence that preferentially binds to the αvβ6 integrin that is highly expressed in a number of epithelial-derived carcinomas. In vitro studies using cancer cell lines expressing the αvβ6 integrin demonstrate that the RGD-lunasin peptide is &gt;10-fold more active in inhibiting cancer cell proliferation than the natural form of lunasin. Moreover, RGD-lunasin inhibits the proliferation of some cancer cell lines that are insensitive to 100 µM lunasin. These results demonstrate the feasibility of utilizing plant-based expression to produce more efficacious forms of lunasin that are targeted specifically to cancer cells and indicate that RGD lunasin may be useful as a cancer therapeutic.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3850. doi:1538-7445.AM2012-3850

Scalable purification and characterization of the anticancer lunasin peptide from soybean

Lunasin is a peptide derived from the soybean 2S albumin seed protein that has both anticancer and anti-inflammatory activities. Large-scale animal studies and human clinical trials to determine the efficacy of lunasin in vivo have been hampered by the cost of synthetic lunasin and the lack of a method for obtaining gram quantities of highly purified lunasin from plant sources. The goal of this study was to develop a large-scale method to generate highly purified lunasin from defatted soy flour. A scalable method was developed that utilizes the sequential application of anion-exchange chromatography, ultrafiltration, and reversed-phase chromatography. This method generates lunasin preparations of >99% purity with a yield of 442 mg/kg defatted soy flour. Mass spectrometry of the purified lunasin revealed that the peptide is 44 amino acids in length and represents the original published sequence of lunasin with an additional C-terminal asparagine residue. Histone-binding assays demonstrated that the biological activity of the purified lunasin was similar to that of synthetic lunasin. This study provides a robust method for purifying commercial-scale quantities of biologically-active lunasin and clearly identifies the predominant form of lunasin in soy flour. This method will greatly facilitate the development of lunasin as a potential nutraceutical or therapeutic anticancer agent.

TNF potentiates anticancer activity of bortezomib (Velcade) through reduced expression of proteasome subunits and dysregulation of unfolded protein response

Bortezomib (Velcade) exploits proteasome inhibition as a unique mechanism of anticancer activity. The effectiveness of bortezomib is, however, limited, therefore, the search for therapeutic regimens combining bortezomib with other agents. In the present work we demonstrate enhanced anticancer activity of bortezomib by its combination with tumor necrosis factor (TNF) in the experimental model of C-26 colon carcinoma in mice. This interaction likely relies on the induction of a dysregulated response to ER stress, leading to apoptosis of cancer cells, evidenced by caspase-3 cleavage, p53 accumulation as well as increased SAPK/JNK phosphorylation. ER stress induced by the combination of TNF and bortezomib is corroborated by upregulation of BiP, PDI and calnexin as well as cleavage of caspase-12; however, in contrast to the classic pathway, it is also associated with decreased phosphorylation of eIF2 alpha and prevention of XBP-1 splicing. TNF prevented the upregulation of Hsp27 induced by bortezomib, which may contribute to enhanced ER stress. Moreover, TNF interfered with bortezomib-induced upregulation of distinct subunits of the 26S proteasome. Bortezomib concentration used in this study was not sufficient to prevent TNF from inducing nuclear translocation of p65/RelA; however, the combination of both agents reduced total p65/RelA levels. Combined treatment of tumor-bearing mice with bortezomib and TNF not only inhibited tumor growth but also significantly prolonged animal survival. Therefore, combination of bortezomib with TNF is an attractive option for further clinical studies.

Lymphoma creating colojejunal fistula: report of a case and review of the literature

Malignant fistula of the colon to the small bowel is rare and is most often due to adenocarcinoma. Colonic lymphoma is unusual, representing only 0.5 percent of all colonic malignancies. We report a case of intestinal lymphoma presenting with diarrhea and malnutrition. A colojejunal fistula was discovered during colonoscopy by biopsy of small bowel through a fistula in the sigmoid colon. Celiotomy revealed a 12 cm mass in the sigmoid colon with a fistula to the jejunum. Pathology was consistent with T-cell lymphoma. This is a rare entity in a nonimmunocompromised host and has not been described in the English literature.

Depletion of activated Vbeta8+ T cells disrupts bispecific antibody directed antitumor immunity

INTRODUCTION

Activation of Vbeta8+ T cells with superantigen staphylococcal enterotoxin B (SEB) and use of an antitumor, anti-CD3 bispecific antibody (BsAb) leads to tumor protective immunity. We hypothesize that Vbeta8+ T-cell activation in combination with BsAb is crucial for tumor protective immunity in this model.

METHODS

Adolescent C3H/HeN mice were intravenously injected with syngeneic CL62 melanoma to establish pulmonary metastasis. Three days after establishing pulmonary metastasis, predominantly Vbeta8+ T cells are activated with 50 mug of intraperitoneal superantigen SEB. T cells were depleted at different time points in relation to SEB administration to assess the effect on protective immunity against a second tumor challenge.

RESULTS

Protective immunity is significantly (P < 0.008) decreased when Vbeta8+ depletion occurs 6 h after SEB injection, as growth of rechallenged CL62 melanoma occurred in 43%. Protective immunity is present at all other time points when mice survive Vbeta8+ T-cell depletion. Survival of animals treated with SEB/BsAb (82%) is significantly better (P < 0.002) than with SEB alone (60%) or nontreated control (0%). Survival when Vbeta8+ T-cell depletion occurred at 6 h and 48 h post-SEB is 72% and 77%, respectfully, and is statistically indistinguishable (P < 0.232 and P < 0.602). If T-cell depletion was conducted before SEB administration, however, the combination of SEB and BsAb did not result in significant protective immunity. T-cell depletion before the use of SEB alone, without BsAb, failed to result in significant protective immunity.

CONCLUSIONS

Depletion of Vbeta8+ T cells 6 h after activation disrupts the development of protective immunity.

Intracellular Ca2+ homeostatic regulation and 4-hydroxynonenal-induced aortic endothelial dysfunction

The aldehydic lipid peroxidation product 4-hydroxynonenal (HNE) is known to compromise erythrocyte passive Ca2+ permeability and to irreversibly inhibit the plasma membrane (Ca2+ + Mg2+)-ATPase and Ca2+-transport. To measure the effects of HNE on passive and active Ca2+ transport in endothelial cells, we first characterized 45Ca2+ uptake and efflux in cultured porcine aortic endothelial cells (PAEC). PAEC exchanged 45Ca2+ to a cumulative near-isotopic equilibrium of about 4.5 pmole 45Ca2+/10(6) cells in 120 min at 37 degrees C. This Ca2+ pool was diminished by thapsigargin, cyclopiazonic acid, oligomycin B, and sodium azide. In contrast, ouabain enhanced Ca2+ uptake capacity from 5.17 to 5.77 pmole/10(6) cells. Accumulated 45Ca2+ was extruded at rate of 8.7 fmole 45Ca2+/10(6) cells/min or shunted rapidly by the ionophore A23187. HNE increased total 45Ca2+ accumulation in a time- and concentration-dependent manner by as much as 562% with an EC50 of 64.0 wM. Concomitant morphological analysis of PAEC revealed vacuolization, nuclear swelling, cell shrinking, and cell detachment. Initial structural changes, such as vacuolization, began well before any changes in Ca2+ accumulation were observed. These functional and morphological changes indicate that HNE significantly increases intracellular Ca2+ accumulation in vascular endothelium, which may explain the cytotoxic effects associated with HNE exposure and provide further evidence that atherogenic effects of HNE may, in part, be caused by disturbances in Ca2+ homeostasis.

Population-based incidence of complicated diverticular disease of the sigmoid colon based on gender and age

PURPOSE

The purpose of this study was to characterize the gender and age differences in patients with clinically symptomatic sigmoid diverticular disease requiring surgery.

METHODS

All surgical patients hospitalized with proven diverticular disease requiring sigmoid resection from January 1988 to January 1998 were reviewed.

RESULTS

A total of 934 patients requiring surgical resection for diverticular disease were admitted. There were 443 men and 491 women with an average age of 64. Forty-nine patients presented with massive rectal bleeding (males, 3.6 percent; females, 1.6 percent), 329 with chronic diverticulitis (males, 15.8 percent; females, 19.3 percent), 61 with obstructive symptoms (males, 2.7 percent; females, 3.9 percent), 148 with fistulas (males, 8.0 percent; females, 7.8 percent), 170 with perforation (male, 8.7 percent; female, 9.4 percent), 79 with abscess (males, 4.0 percent; females, 4.5 percent), 59 with stricture (males, 2.2 percent; females, 4.0 percent), and 39 with acute diverticulitis (males, 2.2 percent; females, 1.9 percent). Overall, patients younger than 50 presented more often with chronic or recurrent diverticulitis.

CONCLUSIONS

Female patients present, on average, five years later than male with complications requiring surgery. Overall, men have a higher incidence of bleeding (P = 0.015), whereas women present more often with stricture and obstruction (P = 0.02). Young males present more with fistula (P = 0.03), whereas older males present with bleeding (P = 0.001). Young females present with perforation (P = 0.002), and older females present with chronic diverticulitis (P = 0.04) and stricture (P = 0.04).

Melanoma metastatic to the colon: case series and review of the literature with outcome analysis

PURPOSE

Symptomatic melanoma of the colon is rare. The aim of this study was to determine the incidence, presenting signs and symptoms, and survival correlation.

METHODS

A retrospective review was performed of all patients treated in Mayo Clinic facilities from 1960 to 2000 for primary and metastatic melanoma. We identified 24 patients with metastatic melanoma to the colon.

RESULTS

There were 24 patients (14 males) with an average age of 60.4 years at the time of metastatic involvement. The interval time between diagnosis of the primary and metastatic disease to the colon was 7.47 years. The most common presentation was bleeding. Colonoscopy was used in 11 patients and diagnostic in 9. Eighteen patients underwent resection, and seven patients had positive nodes. The average time until death after operation was 27.5 months (range, 30 days to 65 months). Nonoperative candidates died within 7.8 months after diagnosis. One-year and five-year survival for resected patients were 37 and 21 percent, respectively. Patients with negative nodes had an average survival time of 34.7 months compared with 20.4 months in patients with positive nodes. Perforation and bowel obstruction directly correlated with poor survival, with an average life expectancy of ten months (P = 0.03).

CONCLUSIONS

Metastatic melanoma of the colon is rare. Segmental resection is justified and can be successfully completed in 95 percent of patients who undergo attempted resection. Survival of less than ten months is most accurately predicted by signs and symptoms of obstruction or perforation at presentation (P = 0.03).

Dendritic cell-tumor cell fusion and staphylococcal enterotoxin B treatment in a pancreatic tumor model

BACKGROUND

Surgical resection of pancreatic tumors removes gross disease but not metastases. Adjuvant therapy such as chemotherapy and radiation treatment is of little value in metastatic pancreatic cancer. The hypothesis of this investigation is that specific and effective immunotherapeutic vaccine (dendritic/tumor cell fusion) will activate cytotoxic T lymphocytes (CTLs), leading to the eradication of spontaneous pancreatic cancer.

METHODS

We have developed a double transgenic mouse model (MET) that forms spontaneous pancreatic tumors and expresses the human MUC1 antigen. Seven-week-old MET mice (n = 8) were treated every 3 weeks with the vaccine. In addition, these mice received 50 microg of superantigen staphylococcal enterotoxin B (SEB), a known T cell stimulant, prior to the first vaccination. A second treatment group received SEB alone (n = 8) and controls received no treatment (n = 9). MUC1-specific CTLs were measured by chromium release assay. At 10 weeks of age and at necropsy, MUC1 serum levels were measured using a MUC1-specific ELISA.

RESULTS

Mice were known to harbor microscopic foci of cancer at birth. Survival was enhanced in vaccine as well as SEB-treated mice (75% CI +/- 0.42) compared to controls (11% CI +/- 0.28) and both groups of treated mice exhibited mature CTLs without in vitro stimulation. MUC1 serum levels of the vaccine group were 50% less than that of control (P < 0.04) at 10 weeks. MUC1 serum levels directly correlated with tumor weight at necropsy (r = 0.86).

CONCLUSIONS

This is the first evidence that MUC1-specific CTLs can be stimulated to enhance survival in a spontaneous tumor model.

ErbB-beta-catenin complexes are associated with human infiltrating ductal breast and murine mammary tumor virus (MMTV)-Wnt-1 and MMTV-c-Neu transgenic carcinomas

Simultaneous deregulation of both Wnt and ErbB growth factors has previously been shown to result in the cooperative induction of mammary gland tumors. Using the murine mammary tumor virus (MMTV)-Wnt-1 transgenic model of mammary carcinoma, we have identified an unvarying association between beta-catenin and epidermal growth factor receptor/c-Neu (ErbB1/ErbB2) heterodimers in mammary gland tumors, indicating a requirement for ErbB signaling in Wnt-mediated tumorigenesis. Expansion of these observations to a second transgenic model, MMTV-c-Neu, demonstrated similar tumor-specific interactions, including an ErbB1 ligand-inducible phosphorylation of both beta-catenin and c-Neu. Direct relevance of these findings to human breast cancer was established upon examination of a set of human infiltrating ductal breast adenocarcinoma and lymph node metastasis tissues taken at surgery. These data revealed increased levels of beta-catenin in tumors and metastases versus normal breast as well as an association between beta-catenin and c-Neu that measurably occurs only in neoplasia, most strongly in metastatic lesions. These studies have identified a seemingly indispensable interaction between beta-catenin and epidermal growth factor receptor/c-Neu heterodimers in Wnt-1-mediated breast tumorigenesis that may indicate a fundamental signaling event in human metastatic progression.

Atypical diverticular disease: surgical results

PURPOSE

Patients with diverticular disease may present with chronic symptoms but never develop diverticulitis. The purpose of this research was to review the outcome of surgical intervention in this subgroup of patients with atypical "smoldering" diverticular disease.

METHODS

Records of 930 patients who underwent sigmoid resection for diverticular disease during a ten-year period at the Mayo Clinic in Rochester, Minnesota, were reviewed. Forty-seven patients (5 percent) fit our inclusion criteria for smoldering diverticular disease and underwent sigmoid colectomy with primary anastomosis. A minimum of 12 months of follow-up was completed in 68 percent of these patients.

RESULTS

Evidence of acute or chronic inflammatory changes was present in 76 percent of resected specimens. Complete resolution of symptoms occurred in 76.5 percent, with 88 percent being pain free.

CONCLUSIONS

We conclude that the diagnosis and presentation of atypical smoldering diverticular disease is an uncommon and poorly defined entity. However, sigmoid resection in this subgroup of patients is safe and is associated with resolution of symptoms in the majority of cases.

Pharmacological and immunohistochemical characterization of calmodulin-stimulated (Ca(2+)+Mg(2+))-ATPase in cultured porcine aortic endothelial cells

Plasma membrane (Ca(2+)+Mg(2+))-ATPase and Ca(2+) transport activities, best characterized in human erythrocytes, are stimulated by calmodulin and thought to play a crucial role in the termination of cellular Ca(2+) signaling in all cells. In plasma membranes isolated from cultured porcine aortic endothelial cells, the (Ca(2+)+Mg(2+))-ATPase was not readily measured. This is in part because of an overabundance of nonspecific Ca(2+)- and/or Mg(2+)-activated ecto-5'-nucleotide phosphohydrolases. Moreover, addition of exogenous calmodulin (10(-9) to 10(-6) mol/L) produced no measurable stimulation of ATPase activities, suggesting a permanently activated state or, alternatively, a complete lack thereof. To establish and verify the presence of a calmodulin-regulated (Ca(2+)+Mg(2+))-ATPase activity in these endothelial cells, immunohistochemical localization using a monoclonal mouse anti-(Ca(2+)+Mg(2+))-ATPase antibody (clone 5F10) was applied to intact pig aorta endothelium, cultured endothelial monolayers, and isolated endothelial plasma membrane fractions. This approach clearly demonstrated Ca(2+) pump immunoreactivity in each of these preparations. To confirm functional calmodulin stimulation of the (Ca(2+)+Mg(2+))-ATPase, 10(-5) mol/L calmidazolium (R24571) was added to the isolated plasma membrane preparation, which lowered the (Ca(2+)+Mg(2+))-ATPase activity from 143.0 to 78.15 nmol P(i)/mg protein x min(-1). This calmidazolium-reduced activity could then be stimulated 113.1+/-0.8% in a concentration-dependent manner by the addition of exogenous calmodulin (10(-7) to 2 x 10(-6) mol/L) with an EC(50) of 3.45+/-0.04 x 10(-7) mol/L (n=4). This represents a competitive lowering of the apparent calmodulin affinity by approximately 100 compared with other unopposed calmodulin-stimulated processes. Together, these findings support evidence for the presence of a calmodulin-stimulated plasma membrane (Ca(2+)+Mg(2+))-ATPase activity in cultured porcine aortic endothelial cells.

Irreversible inhibition of plasma membrane (Ca2+ + Mg2+)-ATPase and Ca2+ transport by 4-OH-2,3-trans-nonenal

4-OH-2,3-trans-nonenal (HNE), a major aldehydic lipid peroxidation product, has been shown to cause cellular toxicities and has been linked to a number of pathophysiological processes including atherogenesis. Specifically, in vitro exposure of erythrocyte plasma membrane preparations to HNE resulted in the inhibition of membrane transport function and integrity. To characterize the nature of the inhibitory effects of HNE on plasma membrane regulatory mechanisms, we investigated its effects on substrate and calmodulin (CaM) stimulation on erythrocyte Ca2+ transport and (Ca2+ + Mg2+)-ATPase activities. Concentration-effect relationship analysis in erythrocyte membrane "ghosts" and inside-out vesicles (IOVs) yielded purely noncompetitive kinetics for Ca2+, ATP, and CaM activation of (Ca2+ + Mg2+)-ATPase and Ca2+ transport. Reductions of Vmax from direct addition of 0.1 mM HNE to the assay incubation mixtures ranged from 23 to 41%. Similarly, pretreatment with HNE of both membrane ghosts and IOVs resulted in a concentration-dependent inactivation of ATPase and transport activities without changes in affinity for Ca2+, ATP, or CaM. Conversely, pretreatment of CaM itself did not impair its ability to stimulate (Ca2+ + Mg2+)-ATPase activity threefold. Moreover, HNE-pretreated membranes exhibited unaltered acetylcholinesterase activity compared to sham-pretreated membranes. Together, these results suggest that HNE may structurally, and thus irreversibly, modify one or more functionally important sites on the transport protein itself.

Inhibition of calmodulin-stimulated (Ca2+ + Mg2+)-ATPase activity by dimethyl sulfoxide

Membrane-bound (Ca2+ + Mg2+)-ATPase activity from human erythrocyte white ghosts in the calmodulin-activated state was inhibited by DMSO in concentrations of 3% (v/v) and above. At 10%, DMSO inhibited calmodulin activation by 47.7%, while basal, calmodulin-independent (Ca2+ + Mg2+)-ATPase and (Mg2+)-ATPase activity remained unaffected. (Na+ + K+)-ATPase activity was also reduced but exhibited a greater IC50. Concentration-effect analyses showed the inhibition by 10% DMSO to be a reversible, non-competitive effect with regard to calmodulin, Ca2+, and substrate activation. Calmodulin-stimulated processes may be more susceptible to inhibition by DMSO than related enzymatic catalysis, and thus may help explain the multitude of reported cellular events caused by the solvent. Furthermore, DMSO affected membrane-associated enzymatic mechanisms opposite to those reported for purified enzyme outside its native membrane environment.

Common carotid artery and tracheal injury from shoulder strap seat belt

Carotid artery injuries from seat belt shoulder straps have been reported involving primarily the internal carotid artery. This paper describes a case of common carotid artery disruption and tracheal transection after a shoulder strap seat belt injury. A successful method for management of this rare injury is presented. Repair involved autogenous arterial replacement in a contaminated field using an interposition graft of superficial femoral artery.

Effects of 4-OH-2,3-trans-nonenal on human erythrocyte plasma membrane Ca2+ pump and passive Ca2+ permeability

Structural and functional alterations of cell membranes caused by free radicals leading to lipid peroxidation and increases in intracellular Ca2+ concentrations have been implicated in atherogenesis. The objective of this study was to directly measure the effects of a major aldehydic lipid peroxidation product, 4-OH-nonenal (HNE), on plasma membrane Ca2+ regulatory mechanisms. This was attained by measuring passive Ca2+ permeability, primary active Ca2+-transport, and (Ca2+ + Mg2+)-ATPase activity in a human red cell model system. Using this three-pronged approach it could be shown that HNE increases passive Ca2+ permeability significantly beyond the typically low basal flux, while at the same time inhibiting the active Ca2+ extrusion pump and associated (Ca2+ + Mg2+)-ATPase activity. We conclude that this deleterious combination of effects by HNE in this plasma membrane model system may be indicative of plasma membrane changes in cells directly involved in atheroma formation and thus may represent causative factors in the early stages of atherogenesis.

Decreased beta-adrenergic receptors in rat brain after chronic administration of the selective serotonin uptake inhibitor fluoxetine

Fluoxetine, a novel antidepressant compound that potently and selectively inhibits serotonin uptake, was chronically administered to laboratory rats. Using in vitro receptor autoradiographic techniques, we found that the binding of [3H]-dihydroalprenolol [( 3H]-DHA) decreased significantly in frontal cortex layers. Analysis of saturation experiments indicated that the reduction was due to a change in number but not affinity of [3H]-DHA binding sites. The data support the hypothesis that the mechanism of action of most antidepressant compounds involves a change in beta-adrenergic receptor function.

Chronic administration of sertraline, a selective serotonin uptake inhibitor, decreased the density of beta-adrenergic receptors in rat frontoparietal cortex

Sertraline, a potent and selective inhibitor of serotonin uptake, was chronically administered to laboratory rats. Using in vitro receptor autoradiographic techniques, we found that the binding of [3H]dihydroalprenolol ([3H]DHA) was reduced in cortex layers IV-VI. Results of a saturation experiment indicated that the reduction in cortex layer IV was due to a change in number but not affinity of beta-adrenergic receptors.

Receptor alterations associated with serotonergic agents: an autoradiographic analysis

Controversy exists concerning whether receptor down-regulation is involved in the efficacy of antidepressants. Many investigators believe that norepinephrine (NE) receptor down-regulation is more important than serotonin (5-HT) receptor down-regulation. The ability to accurately determine which receptor types or subtypes have been down-regulated has been impaired by the lack of sufficiently specific ligands for labeling these receptor subtypes. Studies that have attempted to examine 5-HT2 receptor down-regulation have used [3H]-ketanserin as the ligand of choice to label 5-HT2 receptors, but this ligand also labels a nondescript site. The binding of [3H]-ketanserin to sites other than 5-HT2 receptors can be examined and controlled for by autoradiographic techniques. The authors briefly review potential problems involved in analyzing receptor binding after antidepressant treatment and present new findings of receptor alterations in rat brain as examined by autoradiographic techniques following chronic exposure to fluoxetine (a selective 5-HT uptake inhibitor that has been shown to be an effective antidepressant). Laboratory animals injected with fluoxetine showed receptor down-regulation (reduced density) in the serotonergic system. A provocative and potentially important finding of this study is that this selective 5-HT uptake blocker also down-regulates beta-adrenergic receptors in the CNS.