Oncogenic potential of the adenovirus E4orf6 protein

The group C adenovirus E4orf6 protein has previously been shown to bind to the p53 cellular tumor suppressor protein and block its ability to activate transcription. Here we show that the E4orf6 protein blocks the induction of p53-mediated apoptosis when AT6 cells, which harbor a temperature-sensitive p53, are shifted to the permissive temperature. The E4orf6 protein does not, however, prevent the induction of apoptosis in p53-deficient H1299 cells by treatment with tumor necrosis factor alpha and cycloheximide. The E4orf6 protein also cooperates with the adenovirus E1A protein to transform primary baby rat kidney cells, and it cooperates with the adenovirus E1A plus E1B 19-kDa and E1B 55-kDa proteins to increase the number of baby rat kidney cell transformants and enhance the rate at which they arise. The level of p53 is substantially reduced in transformed cells expressing the E4orf6 protein in comparison to adenovirus transformants lacking it. The E4orf6 gene also accelerates tumor formation when transformed baby rat kidney cells are injected subcutaneously into the nude mouse, and it converts human 293 cells from nontumorigenic to tumorigenic in nude mice. In addition to the well-studied E1A and E1B oncogenes, group C adenoviruses harbor a third oncogene, E4orf6, which functions in some respects similarly to the E1B oncogene.

Prevention of postoperative abdominal adhesions by a sodium hyaluronate-based bioresorbable membrane: a prospective, randomized, double-blind multicenter study

BACKGROUND

Postoperative abdominal adhesions are associated with numerous complications, including small bowel obstruction, difficult and dangerous reoperations, and infertility. A sodium hyaluronate and carboxymethylcellulose bioresorbable membrane (HA membrane) was developed to reduce formation of postoperative adhesions. The objectives of our prospective study were to assess the incidence of adhesions that recurred after a standardized major abdominal operation using direct laparoscopic peritoneal imaging and to determine the safety and effectiveness of HA membrane in preventing postoperative adhesions.

STUDY DESIGN

Eleven centers enrolled 183 patients with ulcerative colitis or familial polyposis who were scheduled for colectomy and ileal pouch-anal anastomosis with diverting-loop ileostomy. Before abdominal closure, patients were randomly assigned to receive or not receive HA membrane placed under the midline incision. At ileostomy closure eight to 12 weeks later, laparoscopy was used to evaluate the incidence, extent, and severity of adhesion formation to the midline incision.

RESULTS

Data were analyzed for 175 assessable patients. While only five (6 percent) of 90 control patients had no adhesions, 43 (51 percent) of 85 patients receiving HA membrane were free of adhesions (p < 0.00000000001). The mean percent of the incision length involved was 63 percent in the control group, significantly greater than the 23 percent observed in patients who received HA membrane (p < 0.001). Dense adhesions were observed in 52 (58 percent) of the 90 control patients, but in only 13 (15 percent) of the 85 receiving HA membrane (P < 0.0001). Comparison of the incidence of specific adverse events between the groups did not identify a difference (P > 0.05).

CONCLUSIONS

This study represents the first controlled, prospective evaluation of postoperative abdominal adhesion formation and prevention after general abdominal surgery using standardized, direct peritoneal visualization. In this study, HA membrane was safe and significantly reduced the incidence, extent, and severity of postoperative abdominal adhesions.

Effects of acepromazine maleate and phenoxybenzamine on urethral pressure profiles of anesthetized, healthy, sexually intact male cats

OBJECTIVES

To evaluate the effects of 2 compounds with alpha adrenergic antagonist properties on the urethral pressures of anesthetized, healthy, sexually intact male cats, and to evaluate one of the compounds for effect on striated muscle.

ANIMALS

20 healthy, sexually intact male cats.

PROCEDURE

Cats were anesthetized with halothane, and urethral pressure profilometry was performed before and after treatment. 125I-labeled alpha-bungarotoxin bound to nicotinic receptors of murine skeletal muscle was used in a competitive binding study with acepromazine maleate.

RESULTS

Acepromazine maleate significantly decreased intraurethral pressures in the preprostatic (19%) and prostatic (21%) regions of the urethra. There was no effect on the postprostatic/penile segment. Acepromazine did not inhibit 125I-labeled alpha-bungarotoxin binding to nicotinic receptors in murine skeletal muscle. Phenoxybenzamine significantly decreased intraurethral pressures (14%) in the preprostatic region of the urethra only.

CONCLUSIONS

Acepromazine maleate and phenoxybenzamine have effects on the smooth muscle of the urethra of healthy, male cats. Acepromazine has no effect on striated muscle.

CLINICAL RELEVANCE

alpha-Adrenergic compounds may be used in the pharmacologic management of feline urinary tract disease.

Topotecan, a topoisomerase I inhibitor, is active in the treatment of myelodysplastic syndrome and chronic myelomonocytic leukemia

The aim of this study was to evaluate the activity of topotecan in patients with myelodysplastic syndrome (MDS) and chronic myelomonocytic leukemia (CMML). Forty-seven patients with a diagnosis of MDS (n = 22) or CMML (n = 25) were treated. The median age was 66 years. Chromosomal abnormalities were present in 70% and thrombocytopenia less than 50 x 10(3)/microL in 51%. Evaluation of outcome and of differences among subgroups was performed according to standard methods; the criteria for response were those used for acute leukemia. Topotecan was administered as 2 mg/ m2 by continuous infusion over 24 hours daily for 5 days (10 mg/m2 per course) every 3 to 4 weeks until remission, then once every month for a maximum of 12 courses. Thirteen patients (28%) achieved a complete response (CR) and six (13%) had hematologic improvement. A CR was achieved in six of 22 patients with MDS (27%) and in seven of 25 with CMML (28%). All eight patients who presented with cytogenetic abnormalities (five chromosome 5 or 7 abnormalities) who achieved CR were cytogenetically normal in CR. Characteristics for which there was evidence of association with a higher response rate were lack of prior chemotherapy, less than 10% marrow monocytes, and absence of RAS oncogene mutations. In contrast, CR rates were similar in patients with or without abnormal karyotypes. Mucositis occurred in 64% of patients (severe in 19%) and diarrhea in 32% (severe in 13%). Febrile episodes occurred in 85% of patients and documented infections in 47%. With a median follow-up duration of 8 months, the 12-month survival rate was 38%, median survival time 10.5 months, and median remission duration 7.5 months. We conclude that topotecan has significant activity in MDS and CMML, with acceptable side effects. Future studies will investigate topotecan combined with topoisomerase II reactive agents, cytarabine, or hypomethylating agents (azacytidine and decitabine).

Frequent infection of peripheral blood CD8-positive T-lymphocytes with HIV-1. Edinburgh Heterosexual Transmission Study Group

BACKGROUND

Although lymphocytes expressing the CD4 surface receptor for HIV-1 have been identified as the principal target of the virus, the extent to which infection of other cell types of the immune system contributes to immunodeficiency is unknown. We investigated the cell types in peripheral blood infected with HIV and the relation of viral load in different subsets to disease progression.

METHODS

The study group consisted of 16 HIV-infected individuals, eight of whom had clinically defined AIDS with CD4 cell counts less than 200/microL blood. The main component subsets of peripheral blood mononuclear cells were purified by magnetic bead separation, and included CD4 and CD8 lymphocytes, B lymphocytes, monocytes, and dendritic cells. HIV proviral sequences within these separate populations were quantified by limiting-dilution nested polymerase chain reaction.

FINDINGS

HIV-1 proviral sequences were detected in T-helper cells, cytotoxic T cells, dendritic cells, and monocytes. CD4 T lymphocytes constituted the main reservoir of HIV in all but one of the symptom-free individuals studied (those with CD4 count > 200/microL). However, in all the individuals with CD4 counts of less than 200/microL, most infected cells within the peripheral blood mononuclear cell fraction were either dendritic cells or CD8 lymphocytes. Infection of CD8 cells accounted for between 66% and 97% of total proviral load in five of the eight AIDS patients. A strong inverse relation between total CD8 count and the frequency of CD8 T-lymphocyte infection was found.

INTERPRETATION

This study provides evidence for widespread infection of lymphocytes of the CD8 phenotype, indicating that HIV-1 has a broader tropism for different cell types in vivo than described for cultured virus. Infection of CD8 cells may contribute to the decline of this subset upon disease progression in HIV-infected individuals. Infection of CD8 cells may or may not occur by a non-CD4-dependent mechanism of virus entry.

Recognition and surgical management of the upper airway resistance syndrome

Patients with upper airway resistance syndrome (UARS) have clinical signs and symptoms of excessive daytime somnolence (EDS) in the absence of obstructive sleep apnea. These patients have increased upper airway resistance, reflected by an elevated intrathoracic pressure measurement, despite a normal respiratory disturbance index (RDI). Physical findings often include excessive palatal tissue and narrowing of the oropharynx and hypopharynx. Nine patients with UARS who received surgical treatment were prospectively evaluated. The four men and five women had signs of EDS, with or without snoring. The mean (+/- standard deviation) RDI was 2.1 (+/- 1.2), and the mean esophageal pressure recording during polysomnography was -36.7 (+/- 16.2) cm H2O. The Epworth sleepiness scale was used to quantify EDS. The preoperative score of 12.0 (+/- 6.6) decreased to 3.4 (+/- 1.9) (P = .001) after surgical treatment. A variety of procedures, all including some type of palatal surgery, were performed. No treatment complications occurred. The recognition of UARS and an understanding of the mechanisms responsible for the progressive development of obstructive sleep apnea syndrome may facilitate the prompt identification and treatment of such patients. The pathophysiology of UARS and a preliminary report of its surgical treatment are discussed.

Gastrointestinal endoscopy in patients taking antiplatelet agents and anticoagulants: survey of ASGE members. American Society for Gastrointestinal Endoscopy

BACKGROUND

Gastrointestinal endoscopy is often required in patients taking aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), or anticoagulants. Because proper guidelines are lacking, we believe that most endoscopists use their own criteria and judgment for stopping and restarting these agents during the periendoscopic period, and the practice varies widely. The aim of our study was to identify these practices among ASGE members.

METHODS

Questionnaires, each containing 22 questions with 157 responses, were sent to 3300 ASGE members, including all Gastroenterology Fellowship Program Directors. One thousand two hundred sixty-nine questionnaires were received and analyzed.

RESULTS

Physicians stopped aspirin and NSAIDs more frequently before colonoscopy (81%) and ERCP (79%) than before upper endoscopy (51%) (p < 0.001). Ninety percent of physicians stopped aspirin and NSAIDs for 10 or fewer days. Only 20% of physicians performed sphincterotomy when aspirin and NSAIDs were not stopped compared with 88% and 85% (p < 0.001 for both) of physicians performing cold biopsies at esophagogastroduodenoscopy and colonoscopy, respectively, and 77% and 69% performing hot biopsies for the same procedures (p < 0.001 for all compared with sphincterotomy). Depending on the indication for anticoagulation, 51% to 60% of physicians stopped warfarin before upper endoscopy; 71% to 82% before colonoscopy; and 26% to 51% of physicians used a "heparin window." All physicians restarted warfarin immediately after diagnostic endoscopy, whereas 80% restarted it 7 or fewer days after therapeutic endoscopy.

CONCLUSIONS

We conclude that a wide variation exists regarding the management of aspirin, NSAIDs, and anticoagulants in the periendoscopic period. There is a definite need for a consensus statement or guidelines for managing patients taking these agents.

Activity of gemcitabine in patients with advanced pancreatic carcinoma. A review

BACKGROUND

In early phase II trials in advanced pancreatic cancer, gemcitabine demonstrated modest antitumor activity. The investigators in these studies reported that gemcitabine should be studied further in view of the degree and frequency of symptomatic improvement observed, the durability of some of the remissions, and the favorable toxicity profile.

METHODS

In order to quantify such symptomatic improvement, a rigorous endpoint of Clinical Benefit was developed that incorporated measures including pain intensity, analgesic consumption and performance status, which have been shown to be reliable and valid endpoints in other studies.

RESULTS

Two trials have been conducted using this methodology in patients with advanced pancreatic carcinoma.

CONCLUSIONS

The results of these studies suggest that gemcitabine is the first cytotoxic agent with any meaningful impact on survival and disease-related symptoms in advanced pancreatic adenocarcinoma. The degree of improvement seen is one which patients with cancer often consider to be most important. Further studies will be required to define more fully the role of gemcitabine in the treatment of pancreatic cancer.

Activity of gemcitabine in patients with advanced pancreatic carcinoma. A review

BACKGROUND

In early phase II trials in advanced pancreatic cancer, gemcitabine demonstrated modest antitumor activity. The investigators in these studies reported that gemcitabine should be studied further in view of the degree and frequency of symptomatic improvement observed, the durability of some of the remissions, and the favorable toxicity profile.

METHODS

In order to quantify such symptomatic improvement, a rigorous endpoint of Clinical Benefit was developed that incorporated measures including pain intensity, analgesic consumption and performance status, which have been shown to be reliable and valid endpoints in other studies.

RESULTS

Two trials have been conducted using this methodology in patients with advanced pancreatic carcinoma.

CONCLUSIONS

The results of these studies suggest that gemcitabine is the first cytotoxic agent with any meaningful impact on survival and disease-related symptoms in advanced pancreatic adenocarcinoma. The degree of improvement seen is one which patients with cancer often consider to be most important. Further studies will be required to define more fully the role of gemcitabine in the treatment of pancreatic cancer.

Primary care physicians and their HIV prevention practices

A national random-sample survey of 4011 primary care physicians was conducted to determine the extent to which they are providing HIV prevention and clinical services, and to learn what characteristics and attitudes might impede the provision of such services. Physicians were asked about their history-taking practices for new adult and adolescent patients, including asking about the use of illicit drugs (injection and noninjection), the number of sexual partners, use of condoms and contraceptives, past episodes of sexually transmitted diseases (STDs), sexual orientation, and sexual contact with partner(s) at high risk for HIV. A preliminary analysis was conducted and reported earlier by the Centers for Disease Control and Prevention (CDC), focusing on the HIV-prevention services being provided by primary care physicians. This report provides additional analyses from this study, focusing on characteristics and attitudes that may prevent physicians from providing these services. Male physicians and the physicians' belief that patients would be offended if asked questions about their sex behaviors were strongly predictive of not asking new patients about their sex and drug behaviors. The physician's specialty was also a strong predictor-OB/GYNs were predictive of asking these questions and GP/FPs were predictive of not asking the questions. Physicians who indicated that a majority of their patients were white were less likely to report asking patients about their sex and drug behaviors. The authors conclude that a substantial number of primary care physicians are missing important opportunities to prevent HIV transmission by not adequately assessing patients' risks and not providing necessary risk-reduction counseling during their physician-patient encounters. Physician's attitudes and beliefs about their patients, as well as their level of experience with HIV, may help to explain these observations.

A rationale for expanding the endpoints for clinical trials in advanced pancreatic carcinoma

BACKGROUND

Using classical endpoints, such as response rate and survival, as the sole measures of benefit, little progress has been made in the treatment of advanced pancreatic carcinoma in the past 30 years. We challenge the assumption that response rate and survival are the only appropriate endpoints for clinical trials in this disease setting.

METHOD

A review of the literature and roundtable discussion were undertaken.

RESULTS

Using current imaging techniques, it is inherently difficult to distinguish pancreatic tumor from normal pancreas, inflammatory tissue, local fibrosis, and unopacified bowel. As a result, objective tumor measurements are often imprecise, unreliable, and irreproducible. This difficulty may explain the wide variation in response rates reported in clinical trials even when the same therapies are used. Tumor-related symptoms, such as anorexia, weight loss, severe pain (requiring opioid analgesia), and impaired functional status, are prevalent and debilitating characteristics of this disease. Tools that can assess these symptoms in a consistent fashion over time have been developed and have been integrated into clinical trials to evaluate new drugs in this setting.

CONCLUSIONS

Systematic assessment of the impact of a new therapy on tumor-related symptoms may provide a sensitive and accurate way to identify useful new treatments for patients with advanced pancreatic carcinoma. Such analyses can be a useful complement to the classical endpoints of response rate and survival.

Purification and activities of the Rhodobacter capsulatus RpoN (sigma N) protein

The rpoN-encoded sigma factors (sigma N) are a distinct class of bacterial sigma factors, with no obvious homology to the major sigma 70 class. The sigma N-containing RNA polymerase holoenzyme functions in enhancer-dependent transcription to allow expression of positively controlled genes. We have purified the Rhodobacter capsulatus sigma N protein, which is distinctive in lacking an acidic region implicated in the melting of promoter DNA by the Escherichia coll sigma N holoenzyme, and may represent a minor subclass of sigma N proteins. Assays of promoter recognition and holoenzyme formation and function showed that the purified R. capsulatus sigma N protein is distinct in activity compared to the enteric proteins, but retains the broad functions described for these proteins. As first described for the Klebsiella pneumoniae protein, promoter recognition in the absence of core RNA polymerase was detected, but contact of certain promoter bases by the R. capsulatus sigma N protein and its response to core RNA polymerase was clearly different from that determined for the K. pneumoniae and E. coli proteins. Results are discussed in the context of a requirement to modulate the activity of the DNA-binding surfaces of sigma N to regulate sigma N function. Circular dichroism was used to evaluate the structure of the R. capsulatus protein and revealed differences in the tertiary signals as compared to the K. pneumoniae protein, some of which are attributable to the DNA-binding domain of sigma N.

The biotransformation of chrysene to trans-1,2-dihydroxy-1,2-dihydrochrysene by filamentous fungi

The purpose of this study was to assess the ability of filamentous fungi isolated from petroleum-contaminated soils to oxidize chrysene. Only 4 of the 17 isolates known to oxidize pyrene and benzo[a]pyrene were found to produce polar products when incubated in the presence of chrysene and Tween 80: Penicillium janthinellum, Syncephalastrum racemosum, and 2 Penicillium spp. Trows-1,2-dihydroxy-1,2-dihydrochrysene was identified by 1H-NMR as one of three fungal metabolites. The extent of bioconversion to diol was approximately 3% of chrysene in 6 days. Experiments to increase chrysene oxidation with other polycyclic aromatic hydrocarbons were not successful. To our knowledge, this is the first identification of a chrysene metabolite from any microorganism and the first report of fungal oxidation of chrysene.Key words: chrysene, polycyclic aromatic hydrocarbons, filamentous fungi, bioremediation, cytochrome P450.

Virologic and immunologic benefits of initial combination therapy with zidovudine and zalcitabine or didanosine compared with zidovudine monotherapy. Wellcome Resistance Study Collaborative Group

A randomized controlled study was done to determine whether initial combination therapy with zidovudine and zalcitabine or zidovudine and didanosine would delay the emergence of zidovudine-resistant virus. Human immunodeficiency virus (HIV)-1-infected patients with <300 CD4 cells/mm3 and <4 weeks of prior zidovudine therapy were randomized to zidovudine, zidovudine plus zalcitabine, or zidovudine plus didanosine. Combination therapy did not delay the emergence of zidovudine-resistant virus isolates. However, combination therapy resulted in a significant increase in CD4 cells through 72 weeks compared with zidovudine monotherapy and a greater and more sustained decline in serum HIV-1 RNA. Although this trial was not designed as a clinical end-point study, patients assigned to zidovudine plus didanosine combination therapy experienced a significant delay in time to first AIDS-defining event or death compared with those assigned to zidovudine monotherapy.

Treatment of sarcoptic mite infestation and mite hypersensitivity in pigs with injectable doramectin

Thirty-two pigs were infested experimentally with Sarcoptes scabiei var suis and allocated randomly to a medicated group (injected intramuscularly with 300 micrograms doramectin/kg) or an unmedicated group (injected intramuscularly with 1 ml saline/33 kg). They were observed daily for 15 minutes for signs of pruritus, and the ear lesions were assessed and skin scrapings examined for mites on days 7, 14, 21 and 28 after treatment. In the 16 pigs treated with doramectin the ear lesions resolved completely within 14 days, no mites were recorded on 15 of them on day 7 or on any of them on days 14, 21 and 28; pruritus was greatly reduced from day 7 onwards (range 0 to 0-62 rubbing episodes per pig per day) and papular skin lesions were absent from 15 of the pigs at slaughter on day 28. In comparison, the ear lesions in the 16 unmedicated pigs failed to resolve in 15 of them. Mites were present on 15 of them at different times during the experiment; the numbers of rubbing episodes ranged from 0.88 to 4.65 per pig per day and all the pigs had papular skin lesions at slaughter. In the unmedicated pigs, both the degree of pruritus and the presence and severity of papular skin lesions at slaughter were greater in those with zero or low mite counts than in those with high mite counts.

Differentiation of follicular dendritic cells and full antibody responses require tumor necrosis factor receptor-1 signaling

Using mice double deficient for tumor necrosis factor (TNF) and lymphotoxin alpha (LT alpha), we demonstrated that TNF and/or LT alpha are necessary for development of a normal splenic microarchitecture and for isotype switch after immunization with sheep red blood cells (SRBC). In the present study, we extended these observations by determining which TNF receptor (TNFR) is involved in morphological and functional differentiation of the spleen. Spleen morphology and antibody response were investigated in wild-type, TNFR1-/-, TNFR2-/- and TNF/LT alpha-/- mice immunized with SRBC. TNF/LT alpha-/- mice, which have a complete disruption of the TNF/LT alpha signaling system including the LT beta-receptor pathway, displayed an abnormal microarchitecture, and isotype switch did not take place. TNFR1-/- and TNFR2-/- mice displayed a normal spleen microarchitecture and mounted an IgM and IgG antibody response to SRBC. However, the IgG production in TNFR1-/- mice was minimal, with citers leveling off 6 d after immunization. In this strain, immunofluorescence revealed a lack of follicular dendritic cells (FDC) network, detected with FDC-M1 as well as anti-CR1, and a lack of germinal centers, detected with peanut agglutinin. In conclusion, whereas normal splenic microarchitecture and isotype switch might require the LT beta receptor, differentiation of FDC network, development of germinal centers, and full IgG response depend on signaling via TNFR1.

Isolation and characterization of variant benzo[a]pyrene-resistant T47D human breast-cancer cells

T47D human breast cancer cells were grown in 1 microM benzo[a]pyrene (BaP) for 3.5 months, and 2 BaP-resistant (BaPr) variant cell lines (CS and C10) were isolated. Decreased aryl hydrocarbon (Ah)-responsiveness in the CS and C1O BaPr cells was characterized by lower (80 to 900/o) induction of CYP1A1-dependent activity by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), lower levels of the nuclear Ah receptor complex and significantly decreased Ah receptor mRNA levels. Nuclear estrogen receptor (ER) binding and ER mRNA levels were similar in wild-type and mutant cell lines, whereas epidermal growth factor receptor mRNA levels were significantly decreased in the variant BaPr T47D cells. 17beta-Estradiol induced proliferation of both wild-type and BaPr T47D cells, and TCDD inhibited this response but did not down-regulate nuclear ER levels. The unique characteristics of the BaPr T47D variant cells will be used to further elucidate the mechanism of interaction between the ER and Ah receptor signalling pathways.

Effect of transient expression of the oestrogen receptor on constitutive and inducible CYP1A1 in Hs578T human breast cancer cells

Hs578T human breast cancer cells are an oestrogen receptor (ER)-negative cell line. Treatment of these cells with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) resulted in formation of a 6.9 S nuclear aryl hydrocarbon (Ah) receptor complex, which bound to a [32P]dioxin-responsive element in a gel electrophoretic mobility shift assay. However, TCDD does not induce CYP1A1 gene expression or chloramphenicol acetyl transferase (CAT) activity in cells transiently transfected with pRNH11c or pMCAT5.12, which are Ah-responsive plasmids derived from the 5'-flanking region of the human and murine CYP1A1 genes respectively. Restoration of Ah responsiveness was investigated by co-transfecting Hs578T cells with pRNH11c or pMCAT5.12 and plasmids that express the ER (hER), Ah receptor (AhR) and AhR nuclear translocator (Arnt) proteins. ER expression resulted in significantly increased basal CAT activity; however, TCDD did not induce CAT activity in the transiently transfected cells. Expression of the AhR or Arnt proteins did not alter basal or inducible CAT activity. Expression of N- or C-terminal truncated ER in Hs578T resulted in differential regulation of Ah responsiveness. In Hs578T cells transiently expressing the ER, which contains C-terminal deletions (amino acids 282-595), basal CAT activity was also increased; however, Ah responsiveness was not restored. In contrast, transient expression of N-terminal-deleted (amino acids 1-178) ER resulted in a marked decrease in basal CAT activity but a restoration of Ah responsiveness. These results suggest that basal and inducible CAT activity in Hs578T cells transiently transfected with pRNH11c is modulated differentially by ER domains that are present in the N- and C-terminal regions of the ER.