Adult intussusception secondary to an appendiceal tumour in a patient with ulcerative colitis: a case report

Background

Intussusception in adult patients is uncommon and appendiceal lead points are particularly rare.

Case presentation

We present the case of a 42-year-old male with a history of ulcerative colitis, presenting with sudden onset abdominal pain and bloody diarrhoea. Endoscopy revealed grossly normal mucosa in the descending colon with a congested polypoid mass in the proximal transverse colon. Computed tomography revealed ileocecal intussusception at the hepatic flexure. A right hemicolectomy was performed, where a grossly dilated appendix was noted, resected and sent for histopathological evaluation. Results revealed low-grade appendiceal mucinous neoplasm. Post-operatively, the patient remained symptom free, however required reintroduction of biologic therapy due to relapse of his ulcerative colitis 12 weeks later.

Conclusion

This case depicts a rare acute surgical presentation and reminds physicians and surgeons of the importance of ‘thinking outside the box’ in clinical practice.

Abstract P6-01-02: Adipose tissue from breast cancer patients with the metabolic syndrome promotes proliferation and invasion of tumor cells and influences expression of genes involved in carcinogenesis

Background: Obesity is a public health issue of global proportions and is recognised as a risk factor for post-menopausal breast cancer. Similarly, the metabolic syndrome (MetS) is recognised as a high risk state for cancer in general. Previously we have shown that the MetS is common in postmenopausal breast cancer patients and is associated with a more aggressive tumor biology. However, the molecular mechanisms by which obesity and/or the MetS promote breast cancer remain unclear. Adipose tissue, including mammary fat, is a functionally active endocrine organ. The aims of this study were to determine whether factors secreted by mammary adipose tissue could affect tumor cell biology and to assess the effect of the MetS on this adipose depot and its subsequent effect on tumor cells.

Methods: Adipose tissue from fresh mastectomy specimens was cultured in serum free media for 72 h to produce adipose conditioned media (ACM). MCF-7 and MDA-MB 231 cell lines were treated with ACM for 24–48 h. Tumor cell function was then assessed by measuring cell proliferation (BrDU assay) and cell invasion. In addition, expression of 84 genes implicated in pathways involved in carcinogenesis was examined in these cell lines following ACM treatment, using quantitative PCR arrays.

Results: In the estrogen receptor (ER) positive MCF-7 cell line, ACM from MetS breast cancer patients promoted significantly greater proliferation compared to ACM from normal weight patients (203.6 ± 34.23 vs 136.8 ± 11.58%, p = 0.022). Similarly, ACM from MetS patients significantly increased invasion of MCF-7 cells compared to ACM from normal weight patients (153.4 ± 6.027 vs 126.3 ± 6.03% RFU, p = 0.006). No differences in cell proliferation or invasion between cells treated with ACM from MetS patients compared to ACM from normal weight patients were found in the ER negative MDA-MB-231 cell line. Treatment of MCF-7 cells with ACM from MetS patients resulted in significant alterations (>2 fold up/down regulation) in expression of 11 genes involved in carcinogenesis. Primarily, genes implicated in invasion/metastasis and adhesion were differentially expressed between ACM-treated cells and cells treated with control media. On the other hand, when MDA-MB-231 cells were treated with ACM from the same patients only one gene, SERPIN B5 was significantly up-regulated > 2 fold.

Conclusions: These data demonstrate that factors secreted from mammary adipose tissue from metabolically unhealthy patients promote proliferation and invasion of ER positive tumor cells and influence expression of genes involved in carcinogenesis in these cells. These effects were not observed in ER negative tumor cells suggesting that they may be mediated, at least in part by the estrogen receptor. These results have provided insight into how mammary adipose tissue may act via a paracrine mechanism to influence aspects of carcinogenesis and into how the metabolic syndrome may modulate this.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-01-02.

Mammary adipose tissue and cancer cell growth: The role of adipose tissue in the tumor microenvironment

e22009

Background: Worldwide, the prevalence of obesity is rapidly increasing, correlating with a direct increase in cancer rates1. Adipose tissue is considered an important endocrine organ producing several important hormones and cytokines including leptin and adiponectin. Mechanisms for the role of obesity in cancer states includes the excess or unregulated secretion of adipocytokines from adipose tissue, and potentially the metabolic syndrome (a cluster of co-morbidities linked to metabolic dysregulation). Mammary adipose tissue is proposed to play a vital role in the microenvironment of normal and tumour states within the breast2. Breast adipose tissue is a good candidate to investigate effects of obesity and metabolic disturbances on cancer states. Methods: Peritumoural (PT) adipose tissue adjacent to the tumour and distal adipose tissue (D) within the breast was sampled in 10 patients. The tissue was processed and cultured for 72hrs in serum free minimal cytokine media. A-MB-231 and MCF-7 breast cancer cell lines were then cultured with this adipocyte conditioned media (ACM) and cell proliferation response was then measured using BrDU assays. The adipocytokine profile at the mRNA and protein level was measured in ACM and adipose tissue for comparative differences using RT-PCR, ELISA and Cytokine Profiler technology. Results: ACM from both sites promoted tumour cell survival. There was however, a differential cell proliferation response noted between the peritumoural (PT) ACM and that from the distant (D) ACM. Pro-inflammatory mediators (VEGF, TNF-α, EGF) were also demonstrated a trend to be differentially expressed between the 2 sites. Conclusions: Proliferation of breast cancer cell lines occurs in response to ACM, with differential effects seen between peritumoural ACM and distant ACM. This may be mediated through increased pro-inflammatory or pro- mitogenic adipocytokine production in adipose tissue surrounding tumour. Further analysis will determine what role obesity and the metabolic syndrome plays in the results noted.

No significant financial relationships to disclose.

Prophylactic surgical uptake in a cohort of BRCA carriers: an Irish perspective

Abstract #3095

Introduction: Women with BRCA 1/2 mutations have a lifetime risk of approximately 45-87%1 for developing breast cancer and a 20-60% risk for ovarian cancer. The managment of these patients including prophylactic surgery is contorversial and presents difficult choices for patients. Uptake of prophylactic surgery in BRCA carriers in an Irish setting has not previously been investigated.
 Methods: St. James hospital is a tertiary referral hospital for BRCA counselling and testing. All information was gathered and analysed from the Cancer genetics department database in our institution which provides a counselling service for a number of hereditary diseases.
 Results: Deleterious BRCA 1/2 mutations have been identified in 57 families since testing began in 1992. There are a total of 109 women in this cohort.
 54% of these women were diagnosed with primary breast cancer. 23 (47.9%) women were symptomatic on presentation. Only 3 (6.3%) were detected during screening. Inital surgery and prophylactic surgery uptake in this group is displayed in table 1.
 31% (n=34) of our BRCA carrier cohort remain unaffected. Uptake of surgical prohylaxis is outlined in table 2. 17 women in this group opted for no form of prophylaxis. 88% of the women will require regular screening for breast cancer.
 Age at bilateral prophylactic masectomy was 30.5 years. Of the 39 women in both groups who elected for bilateral salpingo oophorectomy, only 28% (11) women were under the age of 40 years.
 
 CPM Contralateral Prophylactic Mastectomy
 TAH/BSO Total Abd Hysterectomy/Bilat Salpingo oopherectomy
 
 TAH/BSO Total Abd Hysterectomy/Bilat Salpingo oopherectomy
 BPM Bilateral Prophylactic Mastectomy
 Discussion: Prophylactic mastectomy offers a 95% risk reduction for breast cancer of 95%, despite this, a survival benefit has not been proven. Prophylactic oophorectomy before the age of 40 years has been associated with a reduction in breast cancer of 50% and up to 80% reduction in ovarian/peritoneal malignancy.There is also data to support that oophorectomy provides a survival benefit in BRCA carriers. The rates of uptake of prophylactic surgery in both the affected and unaffected groups in our cohort are lower than that of international standards2. The reasons for this are currently under investigation.
 References:
 1. Ford D et al. Genetic heterogeneity and penetrance analysis of the BRCA1/2 genes in breast cancer families. Am J Hum Genet 1998;62(3):676-89.
 2. Metcalfe KA, et al.International variation in rates of uptake of preventive options in BRCA1/2 mutation carriers. Int J Cancer. 2008 May 1;122(9):2017-22.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3095.

The insulin receptor is essential for virus-induced tumorigenesis of Kaposi's sarcoma

Kaposi sarcoma (KS), a multifocal neoplasm of the skin that can spread to visceral organs, is the most prevalent malignant tumor in acquired immuno deficiency syndrome (AIDS) patients. KS-associated herpesvirus (KSHV or HHV8) is considered the primary etiological factor of this malignancy, as well as of primary effusion lymphoma and multicentric Castleman's disease. KS lesions are characterized by proliferating spindle cells of endothelial cell (EC) origin. The action of the insulin-like growth factor (IGF) system has been implicated in many malignancies, and recent data have demonstrated that the IGF-I receptor (IGF-IR) is required for in vitro growth of the KS-derived KSIMM cell line. To examine whether the IGF pathway is also involved in KSHV-mediated transformation of ECs, we examined the expression and function of the IGF system in KSHV-infected, immortalized dermal microvascular EC (E-DMVEC). The expression of the insulin receptor (IR) was strongly induced in latently infected E-DMVEC, whereas the expression levels of the IGF-IR remained unchanged. Gene knockdown of IR, but not IGF-IR, prevented the characteristic focus formation seen in KSHV-infected E-DMVEC. Similarly, treatment with the IR-specific small-molecule inhibitor HNMPA-(AM(3)) inhibited postconfluent growth. These data suggest a role for the IR, but not the IGF-IR, in KSHV-induced transformation of vascular ECs.

Vibrio cholerae VibF is required for vibriobactin synthesis and is a member of the family of nonribosomal peptide synthetases

A 7.5-kbp fragment of chromosomal DNA downstream of the Vibrio cholerae vibriobactin outer membrane receptor, viuA, and the vibriobactin utilization gene, viuB, was recovered from a Sau3A lambda library of O395 chromosomal DNA. By analogy with the genetic organization of the Escherichia coli enterobactin gene cluster, in which the enterobactin biosynthetic and transport genes lie adjacent to the enterobactin outer membrane receptor, fepA, and the utilization gene, fes, the cloned DNA was examined for the ability to restore siderophore synthesis to E. coli ent mutants. Cross-feeding studies demonstrated that an E. coli entF mutant complemented with the cloned DNA regained the ability to synthesize enterobactin and to grow in low-iron medium. Sequence analysis of the cloned chromosomal DNA revealed an open reading frame downstream of viuB which encoded a deduced protein of greater than 2,158 amino acids, homologous to Yersinia sp. HMWP2, Vibrio anguillarum AngR, and E. coli EntF. A mutant with an in-frame deletion of this gene, named vibF, was created with classical V. cholerae strain O395 by in vivo marker exchange. In cross-feeding studies, this mutant was unable to synthesize ferric vibriobactin but was able to utilize exogenous siderophore. Complementation of the mutant with a cloned vibF fragment restored vibriobactin synthesis to normal. The expression of the vibF promoter was found to be negatively regulated by iron at the transcriptional level, under the control of the V. cholerae fur gene. Expression of vibF was not autoregulatory and neither affected nor was affected by the expression of irgA or viuA. The promoter of vibF was located by primer extension and was found to contain a dyad symmetric nucleotide sequence highly homologous to the E. coli Fur binding consensus sequence. A footprint of purified V. cholerae Fur on the vibF promoter, overlapping the Fur binding consensus sequence, was observed using DNase I footprinting. The protein product of vibF is homologous to the multifunctional nonribosomal protein synthetases and is necessary for the biosynthesis of vibriobactin.

Differential transcription of the tcpPH operon confers biotype-specific control of the Vibrio cholerae ToxR virulence regulon

Epidemic strains of Vibrio cholerae O1 are divided into two biotypes, classical and El Tor. In both biotypes, regulation of virulence gene expression depends on a cascade in which ToxR activates expression of ToxT, and ToxT activates expression of cholera toxin and other virulence genes. In the classical biotype, maximal expression of this ToxR regulon in vitro occurs at 30 degrees C at pH 6.5 (ToxR-inducing conditions), whereas in the El Tor biotype, production of these virulence genes only occurs under very limited conditions and not in response to temperature and pH; this difference between biotypes is mediated at the level of toxT transcription. In the classical biotype, two other proteins, TcpP and TcpH, are needed for maximal toxT transcription. Transcription of tcpPH in the classical biotype is regulated by pH and temperature independently of ToxR or ToxT, suggesting that TcpP and TcpH couple environmental signals to transcription of toxT. In this study, we show a near absence of tcpPH message in the El Tor biotype under ToxR-inducing conditions of temperature and pH. However, once expressed, El Tor TcpP and TcpH appear to be as effective as classical TcpP and TcpH in activating toxT transcription. These results suggest that differences in regulation of virulence gene expression between the biotypes of V. cholerae primarily result from differences in expression of tcpPH message in response to environmental signals. We present an updated model for control of the ToxR virulence regulon in V. cholerae.

Modulation of expression of the ToxR regulon in Vibrio cholerae by a member of the two-component family of response regulators

The ToxRS system in Vibrio cholerae plays a central role in the modulation of virulence gene expression in response to environmental stimuli. An integration of multiple signalling inputs mediated by ToxR, -S, and -T controls virulence gene expression leading to cholera toxin (CT) production. Recently, we identified a new virulence locus, varA (virulence associated regulator), in classical V. cholerae O1 that positively controls transcription of tcpA, the major subunit of the toxin-coregulated pilus (TCP) and the production of CT, two key factors in cholera pathogenesis. The varA locus is a homolog of gacA (originally described for the soil organism Pseudomonas fluorescens), which encodes a conserved global regulator belonging to the family of two-component signal transducing molecules. GacA homologs in a number of diverse gram-negative pathogenic bacterial species have been implicated in controlling the production of diverse virulence factors. varA mutants showed reduced levels of tcpA message and TcpA protein, lacked visible signs of autoagglutination (a phenotype associated with functional TCP), produced decreased levels of CT, and were attenuated in colonizing infant mice. Transcription of varA appears to be independent of ToxR, and overexpression of the regulators tcpPH and toxT from plasmids in the varA mutant restored wild-type levels of CT production and the ability to autoagglutinate. varA represents an additional modulating factor in the coordinate expression of virulence factors in V. cholerae.

Formaldehyde-related textile allergy: an update

Part I of this study explores whether clothing today contains formaldehyde levels likely to cause contact allergy in formaldehyde-allergic patients. Part II of this study examines whether current reactions to textiles may be due to allergy to textile resins and whether individuals with formaldehyde-related textile allergy will react to the newer low formaldehyde resins used in the textile industry. Part I: free formaldehyde was measured in 16 fabric specimens produced in the US and overseas. Additionally, since the textile industry has moved to the use of newer methods for measuring fabric formaldehyde content, the newer methodology was compared with the older methods used in the medical literature. Part II: 10 subjects with known textile contact allergy were patch tested to available Chemotechnique textile resins and 6 new low-formaldehyde resins used by the textile industry. Part I: 8 fabric specimens yielded no detectable formaldehyde and 7 specimens yielded <200 ppm free formaldehyde, using Schiff's reagent and Merck testing methods. 1 specimen showed approximately 2000 ppm formaldehyde, as measured by the Merck test, but only 24 ppm free formaldehyde when retested by the method described in Japanese Law #112. Part II: all subjects reacted strongly to formaldehyde and DMDHEU (the predominant resin currently used in textiles). 6 subjects reacted to EUMF. 2 subjects had mild reactions to the newer low-formaldehyde resins and 1 to the non-formaldehyde Fixapret NF. Our results suggest that most clothing today yields free formaldehyde levels unlikely to cause contact allergy in formaldehyde-allergic individuals. Japanese method #112 is the recommended methodology to measure free formaldehyde in future studies. DMDHEU may now represent the main cause of textile allergy and may be a better screen than EUMF for this problem. Newer resins yielding fabrics with <75 ppm free formaldehyde may cause occasional reactions, but are more likely to be tolerated by individuals with textile contact allergy. Treatment of these individuals should be directed at identification of reliable sources of garments utilizing these newer resins.

Phase variation in tcpH modulates expression of the ToxR regulon in Vibrio cholerae

We evaluated a spontaneous mutant of Vibrio cholerae, which was avirulent in an infant mouse and had reduced expression of cholera toxin and TcpA in response to environmental signals. The toxR, toxS and toxT genes in the mutant were normal, but transcription of toxT was absent. A plasmid expressing wild-type tcpP and tcpH complemented the mutant. The mutation resulted from a frameshift in a string of nine G residues within tcpH; similar slipped-strand mutations in tcpH arose at a frequency of 10(-4) during overnight growth and in the majority of colonies by the end of 5 days of growth in ToxR-inducing conditions. Transcription of tcpPH was regulated by temperature and pH independently of ToxR or ToxT. These results suggest that TcpH couples environmental signals (temperature and pH) to expression of the ToxR regulon, and provide a model for phase variation in the co-ordinate expression of cholera virulence factors.

Protective immunity against Clostridium difficile toxin A induced by oral immunization with a live, attenuated Vibrio cholerae vector strain

Clostridium difficile causes pseudomembranous colitis through the action of Rho-modifying proteins, toxins A and B. Antibodies directed against C. difficile toxin A prevent or limit C. difficile-induced colitis. We engineered plasmid pETR14, containing the hlyB and hlyD genes of the Escherichia coli hemolysin operon, to express a fusion protein containing 720 amino acid residues from the nontoxic, receptor-binding, carboxy terminus of C. difficile toxin A and the secretion signal of E. coli hemolysin A. We introduced pETR14 into Vibrio cholerae and found that the toxin A-HlyA fusion protein was secreted by a number of V. cholerae strains and recognized by both monoclonal and polyclonal anti-C. difficile toxin A antibodies. We introduced pETR14 into an attenuated V. cholerae strain, O395-NT, and inoculated rabbits orally with this construct. Colonization studies disclosed that the V. cholerae vector containing pETR14 was recoverable from rabbit ilea up to 5 days after oral inoculation. Vaccination produced significant systemic anti-C. difficile toxin A immunoglobulin G and anti-V. cholerae vibriocidal antibody responses. Vaccination also produced significant protection against toxin A in an ileal loop challenge assay, as assessed by determination of both fluid secretion and histological changes. These results suggest that the hemolysin system of E. coli can be used successfully in V. cholerae vector strains to effect secretion of large heterologous antigens and that a V. cholerae vector strain secreting a nontoxic, immunogenic portion of C. difficile toxin A fused to the secretion signal of E. coli HlyA induces protective systemic and mucosal immunity against this toxin.

Identification, sequencing, and enzymatic activity of the erythrose-4-phosphate dehydrogenase gene of Vibrio cholerae

We have identified a gene in Vibrio cholerae (epd) which encodes an erythrose-4-phosphate dehydrogenase activity and is located immediately downstream of an iron-regulated virulence gene, irgA, and immediately upstream of a gene encoding phosphoglycerate kinase (pgk). Expression of epd in V. cholerae is not regulated by iron, nor is it required for virulence in an infant mouse model.

Use of cleaved amplified polymorphic sequences to distinguish strains of Staphylococcus epidermidis

We examined the utility of a PCR-based method termed cleaved amplified polymorphic sequences (CAPS) to type 35 well-characterized isolates of Staphylococcus epidermidis. The results were compared with detailed epidemiologic information and typing obtained by using pulsed-field gel electrophoresis (PFGE). To identify CAPS markers for this study, eight pairs of oligonucleotide primers corresponding to five previously sequenced S. epidermidis genes were synthesized and then used to amplify DNA sequences from the S. epidermidis strains by using PCR. Amplified products were reproducibly obtained for seven of eight primer pairs from chromosomal DNA of 33 of the 35 isolates. Seven restriction site polymorphisms were found in five of the amplified products when they were subjected to digestion with a panel of restriction endonucleases. Each fragment-enzyme combination that was polymorphic demonstrated only two alleles in the 33 S. epidermidis isolates analyzed, corresponding to the presence or absence of a single restriction site. Overall, five distinct combinations of alleles were detected and were designated CAPS types A through E. There was a close correlation between the CAPS grouping, the epidemiologic information for the strains, and grouping by PFGE following SmaI digestion of chromosomal DNA. Although PFGE analysis was more discriminatory than typing based on the limited number of CAPS markers used in this study (isolates from the same CAPS group were sometimes distributed into more than one PFGE group), no isolates from the same PFGE group were found in more than one CAPS group. The CAPS procedure was highly reproducible, in contrast to published experience with arbitrarily primed PCR. These preliminary data suggest that CAPS represents a PCR-based technique for strain typing that is highly reproducible, rapid, utilizes widely available technologies, and provides results that are relatively easy to interpret and express.

Relative importance of three iron-regulated outer membrane proteins for in vivo growth of Vibrio cholerae

Iron is an essential nutrient to support the growth of most bacterial species. However, iron is not easily available to microorganisms infecting mammalian hosts, because it is largely sequestered by iron-binding proteins, such as transferrin or lactoferrin, or complexed to heme. In response to environmental iron stress, Vibrio cholerae produces the siderophore vibriobactin as well as a number of iron-induced outer membrane proteins. Previous data on the role of iron acquisition systems for the intraintestinal growth of mucosal pathogens such as V. cholerae are conflicting. In this report, we isolated mutants of V. cholerae with TnphoA fusions in each of viuA, hutA, and irgA, as well as strains mutant in each pair of these genes and all three simultaneously, to analyze the role of these iron-induced outer membrane protein receptors for in vivo growth of V. cholerae. The fusion between hutA and TnphoA in a single copy on the chromosome allowed the study of in vitro regulation of hutA in response to iron, fur, and irgB; transcription of hutA was tightly iron regulated (70-fold) and dependent on a functional Fur but did not require IrgB. To investigate the effects of mutations in these iron-induced outer membrane proteins on in vivo growth, we inoculated ileal loops in a rabbit model of infection. This avoids exposure of organisms to the potential killing effects of gastric acid, allows several logarithmic increases in growth in the in vivo environment, and facilitates direct comparison of multiple strains in the same animal to avoid any differences between animals. We grew each mutant to be tested in competition with the wild-type strain in the same loop, to provide an internal control. We confirmed that the inocula for these experiments were grown under conditions of iron stress prior to in vivo inoculation, by measuring the alkaline phosphatase activity of the iron-regulated fusion in each strain. The results confirmed that mutation of irgA produced a much more substantial in vivo growth defect than mutation of either hutA or viuA alone. Double mutants of irgA with either viuA or hutA, or the strain mutant in all three genes, showed an in vivo growth defect comparable to the strain mutant in irgA only, suggesting that mutation of irgA was the most relevant for in vivo growth. The strain mutant in both hutA and viuA was also markedly impaired for in vivo growth, suggesting that mutation of both of these iron uptake systems simultaneously can also produce a substantial in vivo growth defect.

Heterologous antigen expression in Vibrio cholerae vector strains

Live attenuated vector strains of Vibrio cholerae were derived from Peru-2, a Peruvian El Tor Inaba strain deleted for the cholera toxin genetic element and attRS1 sequences, which was developed as a live, oral vaccine strain. A promoterless gene encoding the Shiga-like toxin I B subunit (slt-IB) was inserted in the V. cholerae virulence gene irgA by in vivo marker exchange, such that slt-IB was under transcriptional control of the iron-regulated irgA promoter. slt-IB was also placed under transcriptional control of the V. cholerae heat shock promoter, htpGp, and introduced into either the irgA or lacZ locus, or both loci, on the chromosome of Peru-2, generating JRB10, JRB11, or JRB12, respectively. A new technique was used to perform allelic exchange with lacZ. This method uses plasmid p6891MCS, a pBR327 derivative containing cloned V. cholerae lacZ, to insert markers of interest into the V. cholerae chromosome. Recombinants can be detected by simple color screening and antibiotic selection. In vitro measurements of Slt-IB produced by the vector strains suggested that expression of Slt-IB from the irgA and htpG promoters was synergistic and that two copies of the gene for Slt-IB increased expression over a single copy. The V. cholerae vectors colonized the gastrointestinal mucosa of rabbits after oral immunization, as demonstrated by very high serum antibody responses to V. cholerae antigens. Comparison of the serologic responses to the B subunit of cholera toxin (CtxB) following orogastric inoculation either with the wild-type C6709 or with Peru-10, a strain containing ctxB regulated by htpGp, suggested that both the cholera toxin and heat shock promoters were active in vivo, provoking comparable immunologic responses. Orogastric inoculation of rabbits with vector strains evoked serum immunoglobulin G (IgG) responses to Slt-IB in two of the four strains tested; all four strains produced biliary IgA responses. No correlation was observed between the type of promoter expressing slt-IB and the level of serum IgG or biliary IgA response, but the vector strain containing two copies of the gene for slt-IB evoked greater serum IgG responses than strains containing a single copy, consistent with the increased expression of Slt-IB from this strain observed in vitro. A comparison of the serum and biliary antibody responses to Slt-IB expressed from htpGp versus CtxB expressed from the same promoter suggested that CtxB is a more effective orally delivered immunogen.

Immunization of sheep against GnRH early in life: effects on reproductive function and hormones in ewes

Groups of Merino ewe lambs were immunized against GnRH either soon after birth (prepubertal) or around puberty (peripubertal) with a prototype commercial preparation and were studied over the following 2 years to determine the long-term effects on reproductive development, function and hormone concentrations. At least 60% of the GnRH-immunized ewes in either treatment group did not experience oestrus and possessed small uteri and small ovaries that lacked follicular development. Growth rates of immunized and control ewes were similar throughout the study. Compared with the increase in plasma LH and FSH concentrations with age in control ewes, the concentrations of these hormones in immunized animals were lower and remained relatively constant from 46 to 90 weeks of age. Plasma FSH concentrations were particularly suppressed in immunized ewes and were significantly (P < 0.05) lower than the control values of 61 and 90 weeks of age. LH release after injection of 1 microgram GnRH at 90 weeks of age was either absent or suppressed in immunized ewes compared with controls. The findings suggest that the lack of GnRH stimulation and consequent deprivation of gonadotrophins, early in the life of ewes, may result in some degree of permanent impairment of hypothalamic and/or pituitary function.

Vibrio cholerae fur mutations associated with loss of repressor activity: implications for the structural-functional relationships of fur

We used the Vibrio cholerae Fur protein as a model of iron-sensitive repressor proteins in gram-negative bacteria. Utilizing manganese mutagenesis, we isolated twelve independent mutations in V. cholerae fur that resulted in partial or complete loss of Fur repressor function. The mutant fur genes were recovered by PCR and sequenced; 11 of the 12 contained point mutations (two of which were identical), and one contained a 7-bp insertion that resulted in premature truncation of Fur. All of the mutants, except that containing the prematurely truncated Fur, produced protein by Western blot (immunoblot) analysis, although several had substantially smaller amounts of Fur and two made an immunoreactive protein that migrated more rapidly on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Nine of the 11 point mutations altered amino acids that are identical in all of the fur genes sequenced so far, suggesting that these amino acids may play important structural or functional roles in Fur activity. Eight of the point mutations occurred in the amino-terminal half of Fur, which is thought to mediate DNA binding; most of these mutations occurred in conserved amino acids that have been previously suggested to play a role in the interaction between adjacent alpha-helices of the protein. Three of the point mutations occurred in the carboxy-terminal half of Fur, which is thought to bind iron. One mutation at histidine-90 was associated with complete loss of Fur function; this amino acid is within a motif previously suggested as being involved in iron binding by Fur. The fur allele mutant at histidine-90 interfered with iron regulation by wild-type fur in the same cell when the mutant allele was present at higher copy number; wild-type fur was dominant over all other fur mutant alleles studied. These results are analyzed with respect to previous models of the structure and function of Fur as an iron-sensitive repressor.

Immunization of sheep against GnRH early in life: effects on reproductive function and hormones in rams

Groups of Merino ram lambs were immunized against GnRH either soon after birth (prepubertal) or around puberty (peripubertal) with a prototype commercial preparation and studied over the following 2 years to determine the long-term effects of such immunization on reproductive development, function and hormone concentrations. The treatment was equally effective in suppressing reproductive function and hormones when given at either time. Growth rates of immunized and controls rams were similar throughout the study. Prepubertal immunization delayed testicular growth until the rams were at least 27 weeks of age and some rams had subnormally sized testes even at 115 weeks of age. After peripubertal immunization, the mass of the testes declined and remained regressed until the rams were from 51 to 90 weeks old. There was a significant correlation between total testicular mass at 115 weeks of age and duration (weeks) of suppression of testicular growth (prepubertal, r = -0.7375; peripubertal, r = -0.7132, P < 0.001). Prepubertal immunization markedly delayed separation of the penis from the prepuce. The immunized rams did not display sexual activity until their total testicular mass reached at least 70 g. In control and immunized rams with testicular mass > 100 g, the semen did not differ in the percentage of spermatozoa that were unstained (live), of normal morphology, or showed progressive movement. Compared with the increase in plasma LH and FSH concentrations with age in control rams, the concentrations of these hormones in the immunized animals were lower and remained relatively constant from 46 to 90 weeks of age.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of oral anticoagulant therapy on APTT results from a bedside coagulation monitor

OBJECTIVE

The Ciba Corning 512 coagulation monitor (CC512) can be used to monitor heparin therapy by performing an activated partial thromboplastin time (APTT) at the patient's bedside. This study was designed to compare the CC512 results to results using the laboratory system. The relative sensitivities of both systems to the effect of oral anticoagulant therapy also was investigated.

METHODS

Activated partial thromboplastin times were performed with both the CC512 and laboratory system on 74 specimens from patients receiving i.v. heparin therapy, and on 14 specimens from patients on warfarin only. Heparin assays were performed on 43 of the specimens from the heparinized patients.

RESULTS

When a patient was receiving heparin only, the APTT results of the CC512 proved to be similar to existing laboratory methods. The CC512 APTT results of patients on warfarin only were markedly prolonged, whereas the laboratory APTTs were only slightly affected.

CONCLUSION

The CC512 results were comparable to the laboratory system. However, the CC512 APTT was more sensitive to the effect of warfarin than the laboratory APTT system used in this study. CC512 APTT results on a patient receiving both oral and intravenous anticoagulation could be misleading.

Toxicity to Chinese hamster ovary (CHO) cells of the products of reaction of butylated hydroxyanisole with nitrite at low pH

Butylated hydroxyanisole (BHA) was found to react readily with nitrite in acidified physiological saline. With low concentrations of reactants at pH 2, HPLC analysis demonstrated the formation of two products, tert-butylquinone (BQ) and a second, unidentified compound. Neutralized BHA/nitrite reaction mixtures were highly toxic to cultured Chinese hamster ovary (CHO) cells. At non-lethal concentrations, causing some cell cycle delay, there was a statistically significant but variable induction of endoreduplication and tetraploidy and a very weak induction of chromosome breakage. The effects were similar to those of pure BQ. It is suggested that the formation of toxic products from BHA, by an oxidative reaction such as that described with nitrite, might be involved in the mechanism of BHA carcinogenesis in the rat forestomach.

A low volume specimen container suitable for monitoring the aPTT of heparinized patients

Differences in the activated partial thromboplastin time (aPTT) were shown when blood taken from patients receiving intravenous heparin therapy was collected into 5 ml and 1 ml citrate containers. Mean aPTTs were 27% shorter with the plasma from the 1 ml citrate containers (n = 23). These results were paralleled by a 37% reduction in the mean heparin concentration (n = 11) and a 77% increase in the mean platelet factor 4 (PF4) concentration (n = 7). This phenomenon is due to increased platelet activation and subsequent increased heparin neutralization in the 1 ml citrate container. In an attempt to overcome this, the citrate was removed from a 1 ml container and replaced with a buffered tri-sodium citrate solution containing theophylline, adenosine and dipyridamole anticoagulant (CTAD). Blood from heparinized patients taken into both 5 ml citrate and 1 ml CTAD showed a correction of the shortening artefact in the low volume container. The mean aPTT of plasmas from the 1 ml CTAD container showed an increase of 10% compared with the 5 ml citrate. There was no significant difference in the mean heparin or PF4 concentrations of blood taken into either container. The 1 ml CTAD tube described is a suitable collection container for monitoring heparin in neonates or patients who are difficult to venepuncture and overcomes the neutralization of heparin in part filled low volume containers.

Influencing decision-making of referring physicians

As marketing budgets for physician liaison departments increase, health care marketers are being held more accountable for their efforts by managers. Market researchers at The Cleveland Clinic Foundation (CCF) have developed a health care organizational information dissemination model that provides an understanding of how referring physicians choose a referral center for their patients. Interviews with 89 new referring physicians show patient influence and interpersonal media to be the two most influential channels of information. Financial analysis of referrals shows that a true physician referral generates significantly more revenue than a patient-influenced referral. CCF managers and marketers have used the data to understand better the effectiveness of their current programs targeted at physicians.

Microsome-mediated clastogenicity of butylated hydroxyanisole (BHA) in cultured Chinese hamster ovary cells: the possible role of reactive oxygen species

Butylated hydroxyanisole (BHA) was found to induce chromosome aberrations in Chinese hamster ovary (CHO) cells in the presence of Aroclor-induced rat-liver S9. The effects were more marked when washed microsomes were employed and chromosome damage was considerably reduced in the presence of catalase, suggesting that hydrogen peroxide was involved. Stimulation of H2O2 production by BHA in S9 or microsome incubation mixtures was demonstrated using the catalase-mediated production of formaldehyde from methanol. One of the major microsomal metabolites of BHA, tert.-butyl hydroquinone (t-BHQ), which autoxidises in solution producing H2O2 also induced extensive catalase-sensitive chromosome damage in the absence of metabolic activation. These observations suggest that extracellular generation of reactive oxygen species may be implicated in the mechanism of BHA clastogenicity in vitro. However, chromosome damage was not completely abolished by catalase and the end product of t-BHQ oxidation, tert.-butyl quinone, was also weakly clastogenic, suggesting that intracellular effects of quinone metabolites may also be involved in the clastogenicity of BHA.