One Health and antimicrobial resistance, a United States perspective

Antimicrobial drugs are a precious resource, responsible for saving millions of lives since their discovery. Unfortunately, some antimicrobials are rapidly losing their effectiveness due to the development and spread of antimicrobial resistance (AMR), a multi-faceted and complex problem affecting humans, animals, plants and the environment. While AMR is a global problem, in this paper, the authors briefly highlight some ongoing efforts in the United States of America aimed at integrating a One Health approach into policies and programmes that address this important health threat.

Splenectomy in a General Hospital

Splenectomy is often performed in patients with malignant disease or trauma who are at a high risk of complications. In the long term, it increases the risk of infection by encapsulated bacteria. An audit was performed to determine the reasons for splenectomy in a district general hospital, to review the results and complications of surgery, and to see how often the patients were prescribed antibacterial prophylaxis. Twenty-eight patients underwent splenectomy in 3 years. The indication was haematological disease in 13 and trauma in four. In the remaining nine the spleen was removed either as part of a radical gastrectomy or during some other abdominal procedure. Six of the 28 patients had died, one within 30 days from disseminated intravascular coagulopathy following an emergency gastrectomy and splenectomy for haematemesis, two from progressive haematological malignant disease, two from non-haematological malignancy, and one from bronchopneumonia. Of the nine patients (32%) with complications, three required a further laparotomy. Most patients had been prescribed pneumococcal vaccine (85%) and prophylactic antibiotics (93%).

Chemotherapy of Chemically-induced Colorectal Tumours

Benign and malignant tumours were induced in the large bowel of rats by the carcinogen 1,2-dimethylhydrazine (DMH). Benign tumours appeared from week 20 onwards and malignant tumours from week 30. 5-Fluorouracil was administered intraperitoneally in maximally tolerated doses from week 26 onwards and failed to influence significantly the development of either benign or malignant tumours. Tumours induced by DMH are a close model of human colorectal cancer and suitable for testing anticancer drugs. Agents with greater activity against colorectal cancer are required.

22-year longitudinal study of repetitive colonoscopy in patients with a family history of colorectal cancer

INTRODUCTION

We report the outcomes of a long-term surveillance programme for individuals with a family history of colorectal cancer.

METHODS

The details of patients undergoing a colonoscopy having been referred on the basis of family history of colorectal cancer were entered prospectively into a database. Further colonoscopy was arranged on the basis of the findings. The outcomes assessed included incidence of cancer and adenoma identification at initial and subsequent colonoscopy.

RESULTS

The records of 2,293 patients (917 men; median patient age: 51 years) were entered over 22 years, giving data on 3,982 colonoscopies. Eight adverse events (0.2%) were recorded. Twenty-seven cancers were found at first colonoscopy and thirteen developed during the follow-up period. There were significantly more cancers identified in those with more than one first-degree relative with cancer than in other groups (p=0.01). The number of adenomas identified at subsequent surveillance colonoscopies remained constant with between 9.3% and 12.0% of patients having adenomas that were removed. Two-thirds (68%) of patients with cancer and three-quarters (77%) with adenomas fell outside the British Society of Gastroenterology (BSG) 2006 guidelines.

CONCLUSIONS

Repeated colonoscopy continues to yield significant pathology including new cancers. These continue to occur despite removal of adenomas at prior colonoscopies. The majority of patients with cancers and adenomas fell outside the BSG 2006 guidelines; more would have fallen outside the 2010 guidelines.

22-year longitudinal study of repetitive colonoscopy in patients with a family history of colorectal cancer

Introduction

We report the outcomes of a long-term surveillance programme for individuals with a family history of colorectal cancer.

Methods

The details of patients undergoing a colonoscopy having been referred on the basis of family history of colorectal cancer were entered prospectively into a database. Further colonoscopy was arranged on the basis of the findings. The outcomes assessed included incidence of cancer and adenoma identification at initial and subsequent colonoscopy.

Results

The records of 2,293 patients (917 men; median patient age: 51 years) were entered over 22 years, giving data on 3,982 colonoscopies. Eight adverse events (0.2%) were recorded. Twenty-seven cancers were found at first colonoscopy and thirteen developed during the follow-up period. There were significantly more cancers identified in those with more than one first-degree relative with cancer than in other groups (p=0.01). The number of adenomas identified at subsequent surveillance colonoscopies remained constant with between 9.3% and 12.0% of patients having adenomas that were removed. Two-thirds (68%) of patients with cancer and three-quarters (77%) with adenomas fell outside the British Society of Gastroenterology (BSG) 2006 guidelines.

Conclusions

Repeated colonoscopy continues to yield significant pathology including new cancers. These continue to occur despite removal of adenomas at prior colonoscopies. The majority of patients with cancers and adenomas fell outside the BSG 2006 guidelines; more would have fallen outside the 2010 guidelines.

Isolated word recognition of silent speech using magnetic implants and sensors

There are a number of situations where individuals wish to communicate verbally but are unable to use conventional means-so called 'silent speech'. These include speakers in noisy and covert situations as well as patients who have lost their voice as a result of a laryngectomy or similar procedure. This paper focuses on those who are unable to speak following a laryngectomy and assesses the possibility of speech recognition based on a magnetic implant/sensors system. Permanent magnets are placed on the tongue and lips and the changes in magnetic field resulting from movement during speech are monitored using a set of magnetic sensors. The sensor signals are compared to sets of pre-recorded templates using the dynamic time warping (DTW) method, and the best match is identified. Experimental trials are reported for subjects with intact larynx, typically using 500-1000 utterances used for speaker dependant training and testing. It is shown that recognition rates of over 90% are achievable for vocabularies of at least 57 isolated words: sufficient to drive command-and-control applications.

The EndoAssist robotic camera holder as an aid to the introduction of laparoscopic colorectal surgery

INTRODUCTION

Introducing laparoscopic colorectal surgery is a challenge to the whole surgical team. It is usual for an assistant to hold the laparoscope and be responsible for the surgeon's view of the operative field and a lack of expertise in the assistant can add significant difficulties. The EndoAssist is a robotic device that replaces the human assistant and ensures steady visualisation of the operative field and a view which can be controlled by the surgeon. This study describes its use in the introduction of laparoscopic colorectal surgery to a unit.

PATIENTS AND METHODS

The EndoAssist was employed for the introduction of laparoscopic colorectal surgery in a unit with previous experience of this device for laparoscopic cholecystectomy. It was used in a consecutive series of 77 laparoscopic colectomy operations.

RESULTS

The robotic device proved successful in the whole range of colorectal operations and a reliable assistant. No problems specific to the device were encountered.

CONCLUSIONS

The EndoAssist robot is a useful laparoscopic assistant and aided in the introduction of laparoscopic colorectal surgery.

Controlled trial of the introduction of a robotic camera assistant (EndoAssist) for laparoscopic cholecystectomy

BACKGROUND

The role of the human camera holder during laparoscopic surgery keeps valuable personnel from other duties. EndoAssist is a robotic camera-holding device controlled by the operator's head movements. This study assesses its introduction into clinical practice.

METHOD

Ninety-three patients undergoing laparoscopic cholecystectomy were randomized to have either the robotic (40) or a human (46) assistant. Seven patients converted to open operation were excluded. Six surgeons were evaluated. Operating time and subjective assessments were recorded. Learning curves were constructed.

RESULTS

The mean operating time was less using the robotic assistant (66 min) than with human assistance (74 min) (p < 0.05, two-tailed t-test). The learning curves for operating time showed that within three operations surgeons were trained in using the robot. The device was safe in use.

CONCLUSION

The EndoAssist operating device is a significant asset in laparoscopic surgery and a suitable substitute for a human assistant. Surgeons became competent in the use of the robot within three operations. The robot offers stability and good control of the television image in laparoscopic surgery.

Avoiding inappropriate surgery for secondary rectal cancer

AIMS

Secondary rectal carcinoma occurs by invasion of the rectum by local primaries or by metastatic spread from a distant primary. The principle management of primary rectal carcinoma is surgery, but this is not usually the case for secondary carcinoma. This study investigates how these two may be differentiated and inappropriate surgery, in particular inappropriate abdominoperineal excision, can be avoided.

METHODS

There were six patients with secondary carcinoma of the rectum. The primary tumours were: prostate (three), endometrium (two), breast (one).

RESULTS

All the patients presented with lower gastrointestinal symptoms and four had a palpable mass on rectal examination. The diagnosis was made on histology and immunohistochemistry. Treatment was with endocrine therapy, chemotherapy, radiotherapy, and surgery. Three patients had palliative surgical procedures, and one had a curative anterior resection. The median survival was 7.5 months.

CONCLUSIONS

This study has found that the presentation of primary and secondary rectal carcinoma is similar, and the method for distinguishing between the two is histology and immunohistochemistry. Staining for prostate-specific antigen was 100% accurate in the diagnosis of secondary rectal carcinoma arising from a prostate primary. The treatment of secondary rectal carcinoma is with systemic therapy and surgery is usually palliative, and therefore abdominoperineal excision should be avoided.

Feasibility study of colonoscopy as the primary screening investigation in relatives of patients with colorectal cancer

AIM

Relatives of patients with colorectal cancer are thought to be at a higher risk for this disease than the average population. We aimed to determine whether colonoscopy is a feasible primary screening investigation for this group to identify premalignant and malignant lesions.

METHODS

A total of 449 people underwent colonoscopy and all had one or more relatives with colorectal cancer, of these, 212 were classified as 'asymptomatic' and 237 as being 'symptomatic'. Colonoscopy commenced at 40 years of age or 10 years younger than the youngest affected relative.

RESULTS

Neoplastic change, benign and malignant, was found in 25.5% of the 'asymptomatic' group and 24% of the 'symptomatic' group; in 26% of those with one first degree relative, 39% with two or more first degree relatives and only 19% with second degree relatives. 38% of lesions were out of reach of a flexible sigmoidoscope. No known complications occurred.

CONCLUSIONS

It is feasible to perform colonoscopy as the primary investigation for the first degree relatives of patients with colorectal cancer. The yield of neoplastic lesions is sufficient to make this appropriate.

Early steps of polyomavirus entry into cells

The mechanism by which murine polyomavirus penetrates cells and arrives at the nucleus, the site of viral replication, is not well understood. Simian virus 40 and JC virus, two closely related members of the polyomavirus subfamily, use caveola- and clathrin-mediated uptake pathways for entry, respectively. The data presented here indicate that compounds that block endocytosis of both caveola- and clathrin-derived vesicles have no effect on polyomavirus infectivity. Polyomavirus does not appear to colocalize with either clathrin light chain or caveolin-1 by immunofluorescence microscopy. Additionally, expression of a dominant-negative form of dynamin I has no effect on polyomavirus uptake and infectivity. Therefore, polyomavirus uptake occurs through a class of uncoated vesicles in a clathrin-, caveolin-1-, and dynamin I-independent manner.

Surgical management of polypoid lesions of the gallbladder

BACKGROUND

With improvements in ultrasonography more polypoid lesions of the gallbladder (PLGs) are being detected. The management of these is controversial.

METHODS

The demographic, radiological and pathological data of 38 patients with ultrasonographically detected PLGs were reviewed. A Medline search for such lesions was performed and a review of the literature is presented.

RESULTS

Thirty-four patients underwent cholecystectomy and four were advised against or declined operation. Of the 34 who had cholecystectomy, 11 had macroscopic and histopathologically proven PLGs. Of these, seven had cholesterol polyps, two had adenomas, one had a carcinoid tumour and one had an adenocarcinoma of the gallbladder. One patient had a histopathologically normal gallbladder. The remainder had chronic cholecystitis with or without gallstones. All of the patients with neoplastic lesions of the gallbladder had solitary polyps greater than 1.0 cm in diameter.

CONCLUSION

A protocol for the management of ultrasonographically detected PLGs is proposed. In this protocol it is suggested that patients with a PLG should undergo surgery if they are symptomatic, or if the PLG is 1.0 cm or more in diameter.

The central proline of an internal viral fusion peptide serves two important roles

The fusion peptide of the avian sarcoma/leukosis virus (ASLV) envelope protein (Env) is internal, near the N terminus of its transmembrane (TM) subunit. As for most internal viral fusion peptides, there is a proline near the center of this sequence. Robson-Garnier structure predictions of the ASLV fusion peptide and immediate surrounding sequences indicate a region of order (beta-sheet), a tight reverse turn containing the proline, and a second region of order (alpha-helix). Similar motifs (order, turn or loop, order) are predicted for other internal fusion peptides. In this study, we made and analyzed 12 Env proteins with substitutions for the central proline of the fusion peptide. Env proteins were expressed in 293T cells and in murine leukemia virus pseudotyped virions. We found the following. (i) All mutant Envs form trimers, but when the bulky hydrophobic residues phenylalanine or leucine are substituted for proline, trimerization is weakened. (ii) Surprisingly, the proline is required for maximal processing of the Env precursor into its surface and TM subunits; the amount of processing correlates linearly with the propensity of the substituted residue to be found in a reverse turn. (iii) Nonetheless, proteolytically processed forms of all Envs are preferentially incorporated into pseudotyped virions. (iv) All Envs bind receptor with affinity greater than or equal to wild-type affinity. (v) Residues that support high infectivity cluster with proline at intermediate hydrophobicity. Infectivity is not supported by mutant Envs in which charged residues are substituted for proline, nor is it supported by the trimerization-defective phenylalanine and leucine mutants. Our findings suggest that the central proline in the ASLV fusion peptide is important for the formation of the native (metastable) Env structure as well as for membrane interactions that lead to fusion.

The dhfr oribeta-binding protein RIP60 contains 15 zinc fingers: DNA binding and looping by the central three fingers and an associated proline-rich region

Initiation of DNA replication occurs with high frequency within oribeta, a short region 3' to the Chinese hamster dhfr gene. Homodimers of RIP60 (replication initiation-region protein 60 kDA) purified from nuclear extract bind two ATT-rich sites in oribeta and foster the formation of a twisted 720 bp DNA loop in vitro. Using a one hybrid screen in yeast, we have cloned the cDNA for human RIP60. RIP60 contains 15 C(2)H(2)zinc finger (ZF) DNA binding motifs organized in three clusters, termed hand Z1 (ZFs 1-5), hand Z2 (ZFs 6-8) and hand Z3 (ZFs 9-15). A proline-rich region is located between hands Z2 and Z3. Gel mobility shift and DNase I footprinting experiments show hands Z1 and Z2 independently bind the oribeta RIP60 sites specifically, but with different affinities. Hand Z3 binds DNA, but displays no specificity for RIP60 sites. Ligation enhancement, DNase I footprinting, and atomic force microscopy assays show that hand Z2 and a portion of the associated proline-rich region is sufficient for protein multimerization on DNA and DNA looping in vitro. Polyomavirus origin-dependent plasmid replication assays show RIP60 has weak replication enhancer activity, suggesting that RIP60 does not harbor a transcriptional transactivation domain. Because vertebrate origins of replication have no known consensus sequence, we suggest that sequence-specific DNA binding proteins such as RIP60 may act as accessory factors in origin identification prior to the assembly of pre-initiation complexes.

Production and characterization of a soluble, active form of Tva, the subgroup A avian sarcoma and leukosis virus receptor

The receptor for the subgroup A avian sarcoma and leukosis viruses [ASLV(A)] is the cellular glycoprotein Tva. A soluble form of Tva, sTva, was produced and purified with a baculovirus expression system. Using this system, 7 to 10 mg of purified sTva per liter of cultured Sf9 cells was obtained. Characterization of the carbohydrate modification of sTva revealed that the three N glycosylation sites in sTva were differentially utilized; however, the O glycosylation common to Tva produced in mammalian and avian cells was not observed. Purified sTva demonstrates significant biological activity, specifically blocking infection of avian cells by ASLV(A) with a 90% inhibitory concentration of approximately 25 pM. A quantitative enzyme-linked immunosorbent assay, developed to assess the binding of sTva to ASLV envelope glycoprotein, demonstrates that sTva has a high affinity for EnvA, with an apparent dissociation constant of approximately 0.3 nM. Once they are bound, a very stable complex is formed between EnvA and sTva, with an estimated complex half-life of 6 h. The soluble receptor protein described here represents a valuable tool for analysis of the receptor-envelope glycoprotein interaction and for structural analysis of Tva.

Controlled intraoperative water testing of left-sided colorectal anastomoses: are ileostomies avoidable?

Anastomotic leakage is a major problem in colorectal surgery, and previous studies have suggested that intraoperative identification of leaks allows repair at the time of surgery. This study examined whether testing allowed a defunctioning ileostomy to be safely omitted. A series of 102 consecutive patients underwent left-sided colorectal resection, 52 males and 50 females, mean age 65.7 years (range 16-89 years). After completion of the anastomosis, its integrity was tested by running saline into the rectum, using a manometer, to a maximum distending pressure of 30 cmH2O. Any leaks were repaired and the anastomosis retested. A defunctioning ileostomy was only performed if the anastomosis could not be shown to be leak-proof on testing. Patients underwent a contrast enema on the 8th postoperative day. Twenty-one (20.6%) patients failed the initial leakage test and 3 (3%) patients failed a second test. Two of these 21 patients went on to have a clinical leak, both of which were treated conservatively. Two defunctioning ileostomies were performed at the time of surgery. Sixteen (16.2%) had a leak on radiological testing, and there was clinical evidence of a leak in 5 (4.9%) patients. There were 3 (2.9%) deaths, but none of these had a leak on radiological testing. Incomplete anastomoses were successfully corrected intraoperatively. A defunctioning ileostomy was avoided in 98% of cases. Intraoperative testing to a pressure of 30 cmH2O is helpful in anterior resection, but does not guarantee that an intact anastomosis will remain intact postoperatively.

Biological effects of gamma-irradiation on laboratory and field isolates of Eimeria tenella (Protozoa; Coccidia)

Sporulated oocysts of a field strain (FS-111) and a laboratory strain (WIS) of Eimeria tenella were exposed to 0, 50, 100, 150, or 200 Gy of gamma-radiation from a 60Co source. Irradiated oocysts of WIS and FS-111 were not significantly more fragile after irradiation as shown by the release of sporocysts after 5-105 s of vortex agitation with glass beads. Excystation was normal in both strains after treatment of the sporocysts with trypsin and sodium taurodeoxycholate, even in groups exposed to 200 Gy of radiation. Sporozoite release from irradiated sporocysts was more rapid than that from unirradiated sporocysts, primarily because of a shorter lag phase during the first 30 min. Irradiated sporozoites were slower to parasitize cultured chick kidney cells than were control sporozoites (4 h postinoculation), but after 24 h there was no significant difference (P < 0.05) between irradiated and control groups except for the WIS treated with 200 Gy. After 48 h, developing schizonts were reduced by 77-94% on exposure to 50-200 Gy. Strain FS-111 did not develop as well as WIS in vitro, but the effect of irradiation was similar. When irradiated oocysts of WIS or FS-111 were inoculated into chickens the prepatent period was unaffected, but fewer oocysts were produced, lesion scores were lower, and the weight gain was less strongly affected in proportion to the doses of radiation. These results suggest that the effects of radiation damage were largely confined to the mechanism of nuclear and cellular reproduction rather than other physiological processes.

Cleavage of rhesus rotavirus VP4 after arginine 247 is essential for rotavirus-like particle-induced fusion from without

We recently described our finding that recombinant baculovirus-produced virus-like particles (VLPs) can induce cell-cell fusion similar to that induced by intact rotavirus in our assay for viral entry into tissue culture cells (J. M. Gilbert and H. B. Greenberg, J. Virol. 71:4555-4563, 1997). The conditions required for syncytium formation are similar to those for viral penetration of the plasma membrane during the course of viral infection. This VLP-mediated fusion activity was dependent on the presence of the outer-layer proteins, viral protein 4 (VP4) and VP7, and on the trypsinization of VP4. Fusion activity occurred only with cells that are permissive for rotavirus infection. Here we begin to dissect the role of VP4 in rotavirus entry by examining the importance of the precise trypsin cleavage of VP4 and the activation of VP4 function related to viral entry. We present evidence that the elimination of the three trypsin-susceptible arginine residues of VP4 by specific site-directed mutagenesis prevents syncytium formation. Two of the three arginine residues in VP4 are dispensable for syncytium formation, and only the arginine residue at site 247 appears to be required for activation of VP4 functions and cell-cell fusion. Using the recombinant VLPs in our syncytium assay will aid in understanding the conformational changes that occur in VP4 involved in rotavirus penetration into host cells.

Comparison of the rotavirus gene 6 from different species by sequence analysis and localization of subgroup-specific epitopes using site-directed mutagenesis

The nucleotide sequence of gene 6 encoding the rotavirus major capsid protein VP6 of EDIM strain (EW) was determined and compared to that of 20 previously reported strains with known subgroup specificities. Multiple alignments of amino acid sequences exhibited a high level of sequence conservation (87 to 99.2%). Site-specific mutagenesis experiments were undertaken to localize regions involved in subgroup specificity. Amino acid positions 305, 315, and a region 296-299 (or 301 for equine strain H-2) were identified as contributing to subgroup epitopes. A single amino acid mutation at position 305 or 315 was sufficient to change the subgroup specificity of EW VP6 protein from non I/II to subgroup I- or subgroup II-like, respectively. Mutation at these sites may be another important mechanism for subgroup variation, along with gene reassortment.

Invasive carcinoma in juvenile polyposis--report of a case in an African patient

Since the 1980s it has been recognized that the polyps of juvenile polyposis have malignant potential. Since the introduction of colonoscopy this syndrome has been redefined and the hamartoma-adenoma-carcinoma sequence recognized. We believe this case is the first report of an invasive carcinoma associated with juvenile polyposis to be described in an African patient.

Chronic parathyroiditis associated with primary hyperplastic hyperparathyroidism

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Immune responses to individual rotavirus proteins following heterologous and homologous rotavirus infection in mice

Serum and intestinal humoral immune responses to rotavirus proteins VP2, VP4, VP6, VP7, NSP2, and NSP4 were quantitatively compared in mice infected with a homologous murine rotavirus (EHPw) or a heterologous simian rotavirus (RRV). Viral protein-specific antibody responses were measured by an immunohistochemistry assay that uses recombinant baculovirus-expressed rotavirus proteins as antigens. In serum, IgG responses to VP6 were dominant and comparable in both RRV- and EHPw-infected groups, but responses to VP2, VP4, VP7, and NSP2 were higher in RRV infection. In feces, IgA responses to VP2, VP4, and VP6 were higher in EHPw-infected mice, but responses to VP7 and NSP2 were detected only in the RRV-infected group. These findings indicate that immune responses to homologous and heterologous rotavirus infection vary both quantitatively and qualitatively. Differences in humoral responses may play a role in the differences in protection induced following homologous or heterologous rotavirus infection.

Virus-like particle-induced fusion from without in tissue culture cells: role of outer-layer proteins VP4 and VP7

We recently described an assay that measures fusion from without induced in tissue culture cells by rotavirus, a nonenveloped, triple-protein-layered member of the Reoviridae family (M. M. Falconer, J. M. Gilbert, A. M. Roper, H. B. Greenberg, and J. S. Gavora, J. Virol. 69:5582-5591, 1995). The conditions required for syncytium formation are similar to those for viral penetration of the plasma membrane during the course of viral infection of host cells, as the presence of the outer-layer proteins VP4 and VP7 and the cleavage of VP4 are required. Here we present evidence that virus-like particles (VLPs) produced in Spodoptera frugiperda Sf-9 cells from recombinant baculoviruses expressing the four structural proteins of rotavirus can induce cell-cell fusion to the same extent as native rotavirus. This VLP-mediated fusion activity was dependent on trypsinization of VP4, and the strain-specific phenotype of individual VP4 molecules was retained in the syncytium assay similar to what has been seen with reassortant rotaviruses. We show that intact rotavirus and VLPs induce syncytia with cells that are permissive to rotavirus infection whereas nonpermissive cells are refractory to syncytium formation. This finding further supports our hypothesis that the syncytium assay accurately reflects very early events involved in viral infection and specifically the events related to viral entry into the cell. Our results also demonstrate that neither viral replication nor rotavirus proteins other than VP2, VP6, VP4, and VP7 are required for fusion and that both VP4 and VP7 are essential. The combination of a cell-cell fusion assay and the availability of recombinant VLPs will permit us to dissect the mechanisms of rotavirus penetration into host cells.

Quantification of systemic and local immune responses to individual rotavirus proteins during rotavirus infection in mice

The purpose of the present study was to develop a quantitative assay that could be used to measure the local and systemic immune responses to specific rotavirus proteins following rotavirus infection of adult mice. To measure these responses, we used an immunocytochemical staining assay of Spodoptera frugiperda (Sf-9) cells which were infected with recombinant baculovirus expressing selected rotavirus proteins. The specificity of the assay was documented by using a series of monoclonal antibodies to individual rotavirus proteins. We observed that the assay had high levels of sensitivity and specificity for a series of VP7- and VP4-specific neutralizing monoclonal antibodies which recognized conformation-dependent epitopes on their target proteins. We also studied immunoglobulin G (IgG) immune responses in serum and IgA immune responses in the stools of mice infected with wild-type murine rotavirus strain EHPw. In both sera and stools, the most immunogenic proteins were VP6 and VP4. VP2 was less immunogenic than VP6 or VP4, and the immune responses to VP7, NSP2, and NSP4 were very low in serum and undetectable in stools.

Receptor-induced conformational changes in the subgroup A avian leukosis and sarcoma virus envelope glycoprotein

We recently reported that Tva, the host cell receptor for subgroup A avian leukosis and sarcoma viruses, binds specifically to the subgroup A envelope glycoprotein (Env-A) (J.M. Gilbert, P. Bates, H. E. Varmus, and J. M. White, J. Virol. 68:5623-5628, 1994). Here we have tested the hypothesis that binding of Tva causes conformational changes in Env-A that correlate with its conversion from a fusion-inactive to a fusion-active state. Conformational changes were examined by both a proteolysis and an immunoprecipitation assay. A temperature-dependent conformational change, demonstrated by the generation of a specific thermolysin digestion product of the surface (SU) subunit, occurred when a soluble form of Tva (sTva) was incubated with Env-A. sTva did not induce this conformational change in Env-C or in a noninfectious precursor form of Env-A, Env-A CL. However sTva did induce the conformational change in Env-A CL that had been pretreated in vitro to produce the SU and transmembrane (TM) subunits. Moreover, interaction of Tva with Env-A at 25 degrees C, but not at 4 degrees C, appeared to reveal a previously buried segment of the putative fusion peptide of Env-A. Our results suggest that binding of Tva to Env-A results in specific conformational changes in the Env-A glycoprotein that are relevant to the activation of its fusion function.

Rotavirus-induced fusion from without in tissue culture cells

We present the first evidence of fusion from without induced in tissue culture cells by a nonenveloped virus. Electron micrographs of two strains of rotavirus, bovine rotavirus C486 and rhesus rotavirus, show that virally mediated cell-cell fusion occurs within 1 h postinfection. Trypsin activation is necessary for rotavirus to mediate cell-cell fusion. The extent of fusion is relative to the amount of virus used, and maximum fusion occurs between pHs 6.5 and 7.5. Fusion does not require virus-induced protein synthesis, as virus from both an empty capsid preparation and from an EDTA-treated preparation, which is noninfectious, can induce fusion. Incubation of rotavirus with neutralizing and nonneutralizing monoclonal antibodies before addition to cells indicates that viral protein 4 (VP4; in the form of VP5* and VP8*) and VP7 are involved in fusion. Light and electron micrographs document this fusion, including the formation of pores or channels between adjacent fused cells. These data support direct membrane penetration as a possible route of infection. Moreover, the assay should be useful in determining the mechanisms of cell entry by rotavirus.

The receptor for the subgroup A avian leukosis-sarcoma viruses binds to subgroup A but not to subgroup C envelope glycoprotein

The putative subgroup A avian leukosis-sarcoma virus (ALSV) receptor (Tva) was recently cloned by gene transfer (P. Bates, J. A. Young, and H. E. Varmus, Cell 74:1043-1051, 1993; J. A. T. Young, P. Bates, and H. E. Varmus, J. Virol. 67:1811-1816, 1993). Susceptibility to infection by subgroup A ALSV is conferred on cells upon transfection with cDNAs encoding tva. The hypothesis that tva encodes a specific receptor for subgroup A ALSV predicts that the Tva protein should bind to subgroup A, but not to subgroup C, envelope glycoprotein. In this study, we examined this prediction by using several biochemical assays. We established stable NIH 3T3 cell lines expressing either Tva, the subgroup A envelope glycoprotein (Env-A), or the subgroup C envelop glycoprotein (Env-C) and used them in conjunction with soluble forms of these molecules to demonstrate specific binding. When cell lysates containing Tva were mixed with lysates of either Env-A or Env-C, an immunoprecipitable complex formed between Tva and Env-A but not between Tva and Env-C. A soluble, oligomeric form, of Env-A, not Env-C, binds to cells expressing Tva. Reciprocally, a secreted form of Tva can bind to cells expressing Env-A but not to cells expressing Env-C. A specific and stable complex formed between soluble Env-A and secreted Tva as demonstrated by sucrose density gradient centrifugation. Thus, by three kinds of assays, Tva appears to bind specifically to Env-A, which is consistent with genetic evidence that it serves as the cell surface receptor of subgroup A ALSV and the main determinant of subgroup specificity.

Simple method to purify chicken immunoglobulin G

A new method for purifying IgG was adapted for use with chicken serum. Chicken serum was mixed with caprylic acid, precipitated with ammonium sulfate, and dialyzed against PBS. Analysis by SDS-PAGE and Western blot confirmed successful purification of chicken IgG. Large quantities of highly purified IgG were easily obtainable for use in immunological investigations or for labeling. This technique is rapid, inexpensive, and simpler to perform than traditional ion exchange or gel filtration chromatography.

Generation of a water-soluble oligomeric ectodomain of the Rous sarcoma virus envelope glycoprotein

Sequences encoding the transmembrane domain of the Rous sarcoma virus envelope (Env) glycoprotein were deleted and replaced with sequences that signal addition of a glycosyl phosphatidylinositol (GPI) membrane anchor. Stable NIH 3T3 cell lines expressing either the wild-type transmembrane-anchored Env or the Env chimera with a GPI tail were established. The GPI-anchored envelope glycoprotein is expressed, oligomerized, and transported to the cell surface in a manner identical to that of its wild-type transmembrane-anchored counterpart. The GPI-linked protein is quantitatively removed from the cell surface by treatment with phosphatidylinositol phospholipase C. The phosphatidylinositol phospholipase C-released, water-soluble Env glycoprotein ectodomain retains the wild-type oligomeric structure and provides a useful tool for studying the subgroup-specific binding and fusion activities of a prototypic retroviral Env glycoprotein.

Electrophoretic and immunologic characterization of proteins of merozoites of Eimeria acervulina, E. maxima, E. necatrix, and E. tenella

Merozoites of Eimeria acervulina, Eimeria maxima, Eimeria necatrix, and Eimeria tenella were compared by gel electrophoresis, western-blotting with chicken antiserum, indirect fluorescent antibody reactions, and antiserum neutralization. Merozoites from the 4 species had dissimilar patterns of proteins and antigens in soluble and membrane fractions. Coomassie blue staining of SDS-PAGE gels revealed 16-22 protein bands depending on the species of merozoite but only 3 bands per species in the membrane fractions. Homologous and heterologous antisera recognized 5-12 soluble fraction bands and 3-7 membrane fraction bands on immunoperoxidase-stained western blots, depending on the species. When antisera from infected chickens were used in an indirect fluorescent antibody reaction, the merozoites of E. tenella and E. necatrix had a strong reaction with homologous and heterologous antisera. Merozoites of E. acervulina and E. maxima reacted with homologous antisera but had a weak or no reaction with heterologous antisera. Chicken antiserum against E. tenella had no effect on the viability of E. tenella merozoites when they were inoculated into chicken embryos.

Effects of Eimeria brunetti infection and dietary zinc on experimental induction of necrotic enteritis in broiler chickens

Broilers infected with Eimeria brunetti and given dietary zinc were examined for experimental induction of necrotic enteritis. Inoculation with sporulated E. brunetti oocysts at 7 days of age was followed by 5 consecutive days of oral inoculation with cultured Clostridium perfringens. Feed was supplemented with zinc at 1000 ppm. Upon necropsy of broilers 6 days after coccidial inoculation, necrotic enteritis was found in 20% (2/10) of birds given both organisms and dietary zinc. Coccidial lesion scores were also highest in that group. Birds infected with E. brunetti and C. perfringens with no dietary zinc had significantly higher coccidiosis lesion scores (P less than 0.05) than groups inoculated with E. brunetti only, regardless of zinc supplementation. Alpha toxin levels in intestinal contents were low in groups infected with both organisms, regardless of zinc supplementation. Zinc was tested for effects of alpha toxin production in vitro. In the mid-log phase (6 hours incubation), a high level of alpha toxin was produced in zinc-supplemented media, but this was lost quickly in the presence of trypsin. Addition of zinc partly protected the toxin from the action of trypsin.

The aetiology and surgery of carcinoma of the anus, rectum and sigmoid colon in Crohn's disease. Negative correlation with human papillomavirus type 16 (HPV 16)

Anal and recto-sigmoid Crohn's disease may rarely be complicated by the development of local malignancy. Eight patients with this association were identified from the records of St. Mark's Hospital between 1947 and 1988 and two from The London Hospital. The aetiology of the malignancies and their surgical management have been examined. Eight patients had adenocarcinoma of the anus, rectum or sigmoid colon and two had squamous cell carcinoma of the anus. Synchronous dysplasia, adenomas and carcinomas were found in four of the eight patients with adenocarcinoma and a progression to malignancy which is analogous to that in ulcerative colitis is proposed for these cases via a 'dysplasia-carcinoma' or 'adenoma-carcinoma' sequence. In the four other patients with adenocarcinoma, the tumour arose within an area of Crohn's disease or in association with a chronic Crohn's fistula. In these four cases no dysplasia was found in the specimens at that time and long-standing infection is the only aetiological factor identified. Evidence for infection with human papillomavirus (HPV 16) was sought by DNA hybridisation of archival material but none was found in material from the Crohn's disease, fistulae or adeno- or squamous cell carcinomas. Anal and rectosigmoid Crohn's disease disguised the presence of malignancy, and diagnosis was usually delayed. All patients underwent excisional surgery and eight of the ten had all of the large bowel removed either as a single procedure or in stages. Only three of the eight cases of adenocarcinoma had early malignancies (Dukes' stage A) and the remaining five cases had locally advanced disease (Dukes' stage B).

Prevention of postoperative renal dysfunction in patients with obstructive jaundice: a multicentre study of bile salts and lactulose

The role of preoperative lactulose and bile salts in the prevention of postoperative renal failure in patients with obstructive jaundice has been evaluated in a prospective randomized trial. One hundred and two patients undergoing surgery for obstructive jaundice (bilirubin greater than 100 mumols/l) were randomized into three groups: those receiving preoperative oral lactulose (n = 35), those receiving oral sodium deoxycholate (n = 32) and a control group of patients receiving no specific treatment (n = 35). All patients received intravenous fluids commencing the night before surgery. One patient in the control group and none in the treatment groups developed postoperative renal failure. Postoperative deterioration of renal function in patients with normal preoperative function was significantly more common in the control group than in the treatment groups (chi 2 = 8.1, d.f. = 2, P less than 0.02). The incidence of renal failure and impairment was lower in this control group than that reported in previous studies. This may be due to the introduction of adequate preoperative hydration. Additional protection occurs by the preoperative administration of either lactulose or sodium deoxycholate.

Evaluation of anticoccidial drugs in chicken embryos

Infections of Eimeria tenella in chicken embryos were used to compare the anticoccidial activity of ten drugs. The minimal inhibitory concentration (MIC) and minimal toxic concentration (MTC) were affected by the time of inoculation into the embryos and by the chemical nature of the compounds. Some compounds (nicarbazin, amprolium) had no effect on the development of coccidia when they were injected into embryos after the day of infection. Drugs that act early in the life cycle of coccidia (robenidine, clopidol, decoquinate, diclazuril, halofuginone, monensin, salinomycin, and lasalocid) were active at 5-125 micrograms/embryo when they were injected on the day of infection. The ionophores and halofuginone were highly toxic to embryos; most synthetic compounds were nontoxic. The incubation of merozoites in drug suspensions prior to the infection of embryos did not result in embryo toxicity, but the resultant MICs were much higher than those obtained when drugs were injected directly into the embryos. Several products were essentially inactive. Neither nicarbazin nor amprolium prevented oocyst formation. The widely divergent endpoints for the MIC and MTC of anticoccidials in embryos seriously limits the application of this technique as a screen for anticoccidial drugs.

Fusion of Rous sarcoma virus with host cells does not require exposure to low pH

We investigated whether Rous sarcoma virus (RSV) infects cells through a pH-independent or a low-pH-dependent pathway. To do this, the effects of lysosomotropic agents and acid pretreatment on RSV infectivity of, and fusion with, chicken embryo fibroblasts (CEFs) were studied. High concentrations of lysosomotropic agents (ammonium chloride and monensin) did not inhibit virus infectivity: equal titers of RSV were produced in the presence and absence of these agents. Similarly, low-pH pretreatment did not inhibit RSV infectivity. In parallel experiments, lysosomotropic agents and acid pretreatment completely abolished the ability of influenza virus to infect CEFs. To monitor the fusion activity of RSV directly, the viral membrane was labeled with the fluorescent lipid probe octadecyl rhodamine at a self-quenching concentration. Upon fusion with a host cell, the probe is diluted in the cell membrane, resulting in fluorescence dequenching (D. Hoekstra, T. de Boer, K. Klappe, and J. Wilschut, Biochemistry 23:5675-5681, 1984). In this assay, fusion of RSV with CEFs was found to occur in both a time-dependent and a strictly temperature-dependent fashion. No fusion occurred unless cells with prebound virus were warmed to temperatures greater than 20 degrees C. Fusion, but not binding, was abolished if virus was pretreated with low concentrations of glutaraldehyde. High concentrations of ammonium chloride had no effect on fusion of RSV with CEFs but greatly diminished the ability of influenza virus and Semliki Forest virus to fuse with CEFs. Similarly, acid pretreatment of RSV had no effect on fusion with CEFs while markedly inhibiting fusion of both influenza and Semliki Forest viruses. Collectively, our results show that RSV fusion with and hence infection of CEFs does not require exposure of the virus to low pH. In this respect, RSV resembles another retrovirus, human immunodeficiency virus.

Ocular manifestations and impression cytology of anorexia nervosa

A prospective age- and sex-controlled study of seven anorexia nervosa patients and seven normal control patients was conducted to determine the ocular manifestations of anorexia nervosa. Slit-lamp examination of the anorexic patients demonstrated a high incidence (4/7) of multiple episcleral capillary aneurysms and subconjunctival hemorrhages. Two of seven anorexia nervosa patients had bilateral superficial punctate keratopathy. Anesthetized Schirmer tear testing demonstrated a significantly (P less than 0.005) reduced mean tear production in the anorexia nervosa group (11.3 mm) compared with the control group (22.4 mm). Masked interpretation of conjunctival impression cytology demonstrated moderate to severe conjunctival squamous metaplasia in the majority of the anorexia nervosa group (5/7) compared to normal conjunctival epithelium in the majority of the control group (5/7). Absence of nyctalopia, Bitot's spots, and xerosis, and lack of conjunctival goblet cell loss indicate that the anorexia nervosa group did not have vitamin A deficiency.

Surgical correction of the efferent ileal limb for disordered defaecation following restorative proctocolectomy with the S ileal reservoir

The S ileal reservoir has been superseded in this unit but 76 patients had this operation between 1976 and 1983. Forty-one (54 per cent) patients had to catheterize the reservoir to evacuate faeces and this was primarily due to the long efferent ileal limb. In six patients, the need to catheterize and other problems with defaecation were such that surgical correction of the efferent ileal limb was undertaken. These six patients are reported. Presenting features were the need to catheterize the reservoir, difficulty in catheterizing, faecal incontinence, stenosis of the efferent ileal limb and transanal prolapse of the efferent ileal limb. All patients had an excessively long efferent ileal limb of 8 cm or more which was resected and reanastomosed to the anal canal. The resection was performed endoanally in three patients but was successful in only one. In the two patients in whom endoanal excision was unsuccessful and in the remaining three resection of at least 5 cm was performed transabdominally with endoanal reanastomosis. Three of these five patients were converted from catheterizing the reservoir to spontaneous evacuation, but two patients still needed to catheterize. All six patients benefited in terms of the need for, or frequency of, catheterization, or by improvement in continence. Excessive length of the efferent limb of an S ileal reservoir may cause unsatisfactory defaecation, which may be improved by partial resection. The transabdominal route is recommended for the resection, with endoanal reanastomosis. This surgery is potentially problematic and, although no anastomotic leakage was encountered, a covering loop ileostomy is recommended.

A new method for purification of Eimeria tenella merozoites

A rapid and simple method for purifying second generation merozoites of Eimeria tenella was developed using a host tissue digestion fluid, containing 0.25% trypsin and 0.5% taurodeoxycholic acid, to liberate merozoites grown in chick embryos or from parasitized ceca. After filtration, the digestion procedure yielded 1.4 x 10(7) or 8.33 x 10(7) merozoites per embryo or cecum, respectively. These yields were nine-fold for embryos and three-fold for ceca in comparison to previous reports. Viability of the merozoites was normal as assessed by their ability to reinfect embryos and cell cultures. The new method has advantages in that large numbers of pure, viable merozoites can be obtained quickly and easily, and the procedures require minimal effort and supplies.