Vascular endothelial growth factor is an in vivo survival factor for tumor endothelium in a murine model of colorectal carcinoma liver metastases

BACKGROUND

Recent studies have suggested that vascular endothelial growth factor (VEGF), in addition to its proangiogenic properties, also functions as a survival factor for endothelial cells. The authors hypothesized that inhibition of VEGF activity by blockade of VEGF receptor-2 (R-2) function prevents angiogenesis and decreases tumor growth in colon carcinoma liver metastases.

METHODS

Spleens of mice were injected with human colon carcinoma cells producing liver metastases. After 7 days of tumor growth, groups of mice received either antibody to VEGFR-2 (DC101) or phosphate-buffered saline (control). In a follow-up experiment, a similar treatment regimen was followed except that mice were sacrificed at 1-week intervals to assess the time course of endothelial cell and tumor cell apoptosis.

RESULTS

After 21 days of therapy, the authors observed a significant decrease in vessel counts in liver metastases from human colon carcinoma in nude mice after therapy with VEGFR-2 antibody. Tumor cell apoptosis was increased significantly in the tumors of mice receiving DC101. Temporal studies with immunofluorescent double staining for the microvasculature and apoptotic cells revealed an increase in endothelial cell apoptosis that preceded an increase in tumor cell apoptosis. In vitro, treatment of human umbilical vein endothelial cells with antibody to VEGFR-2 produced a > 2.5-fold increase in endothelial cell apoptosis.

CONCLUSIONS

Therapy targeting the VEGFR-2 inhibited tumor growth in a murine model of colon carcinoma liver metastasis. Surprisingly, this therapy did not only inhibit angiogenesis but also led to endothelial cell death. These findings suggest that VEGF, via VEGFR-2 signaling, functions as a survival factor for tumor endothelial cells in liver metastases from colon carcinoma.

Vascular endothelial growth factor is an in vivo survival factor for tumor endothelium in a murine model of colorectal carcinoma liver metastases

BACKGROUND

Recent studies have suggested that vascular endothelial growth factor (VEGF), in addition to its proangiogenic properties, also functions as a survival factor for endothelial cells. The authors hypothesized that inhibition of VEGF activity by blockade of VEGF receptor-2 (R-2) function prevents angiogenesis and decreases tumor growth in colon carcinoma liver metastases.

METHODS

Spleens of mice were injected with human colon carcinoma cells producing liver metastases. After 7 days of tumor growth, groups of mice received either antibody to VEGFR-2 (DC101) or phosphate-buffered saline (control). In a follow-up experiment, a similar treatment regimen was followed except that mice were sacrificed at 1-week intervals to assess the time course of endothelial cell and tumor cell apoptosis.

RESULTS

After 21 days of therapy, the authors observed a significant decrease in vessel counts in liver metastases from human colon carcinoma in nude mice after therapy with VEGFR-2 antibody. Tumor cell apoptosis was increased significantly in the tumors of mice receiving DC101. Temporal studies with immunofluorescent double staining for the microvasculature and apoptotic cells revealed an increase in endothelial cell apoptosis that preceded an increase in tumor cell apoptosis. In vitro, treatment of human umbilical vein endothelial cells with antibody to VEGFR-2 produced a > 2.5-fold increase in endothelial cell apoptosis.

CONCLUSIONS

Therapy targeting the VEGFR-2 inhibited tumor growth in a murine model of colon carcinoma liver metastasis. Surprisingly, this therapy did not only inhibit angiogenesis but also led to endothelial cell death. These findings suggest that VEGF, via VEGFR-2 signaling, functions as a survival factor for tumor endothelial cells in liver metastases from colon carcinoma.

Cooperation of bcl-2 and myc in the neoplastic transformation of normal rat liver epithelial cells is related to the down-regulation of gap junction-mediated intercellular communication

The objectives of this study were to isolate several rat liver epithelial cell clones containing the human bcl-2 and myc/bcl-2 genes in order to study their potential cooperative effect on neoplastic transformation and gap junction-mediated intercellular communication (GJIC) and to test the hypothesis that the loss of GJIC leads to tumorigenesis. Using anchorage-independent growth as a surrogate marker for neoplastic transformation, we transfected both normal rat liver epithelial cells, WB-F344, and a WB-F344 cell line overexpressing v-myc with human bcl-2 cDNA. Those cell lines that only expressed v-myc or human bcl-2 were unable to form colonies in soft agar. However, those cell lines that overexpressed both v-myc and human bcl-2 showed varying ability to form colonies in soft agar, which did not correlate with their human bcl-2 expression level. In order to test if there was a correlation between cell line growth in soft agar and the ability to communicate through gap junctions, we performed scrape load dye transfer and fluorescence recovery after photobleaching assays. Our results show that v-myc and human bcl-2 can cooperate in the transformation of normal cells, but the degree to which the cells are transformed is dependent on the cells' ability to communicate through gap junctions.

Development and analysis of various clonal alloantigen-dependent cytotoxic cell lines from channel catfish

To determine the phenotypes of cytotoxic cells in channel catfish, clonal alloantigen-dependent leukocyte lines were established from mixed leukocyte cultures. Each clone was analyzed for expression of TCR alpha and beta genes by RT-PCR and for target cell specificity by 51Cr-release assay. Based on the above criteria, the following five different cell types were identified among the 19 clones analyzed: 1) TCR alphabeta+ allospecific cytotoxic cells, 2) TCR alphabeta+ nonspecific cytotoxic cells, 3) allospecific TCR alphabeta+ noncytotoxic cells, 4) TCR alphabeta- nonspecific cytotoxic cells, and 5) TCR alphabeta- allospecific cytotoxic cells. The demonstration of cloned, TCR alphabeta+, allospecific cytotoxic effectors provides the strongest evidence to date for the existence of cytotoxic T cells in fish.

Cell population dynamics (apoptosis, mitosis, and cell-cell communication) during disruption of homeostasis

The sequence of events involved in maintenance of homeostasis must encompass mechanisms within single cells as well as interactions between cells within a population. To investigate the interaction among these inter- and intracellular mechanisms, disruption of homeostasis by serum deprivation was performed in WB-F344, a normal diploid epithelial cell line. Changes in cell-cell communication (gap junction function) at the population level and in individual cells were monitored using the scrape load/dye transfer and fluorescence redistribution after photobleaching assays. Apoptosis and mitosis were measured using internucleosomal DNA ladder assays and fluorescence-activated cell sorting. The results indicate that a common element in early apoptosis and early mitosis is sustained gap junction function. As cell life (mitosis) and cell death (apoptosis) progressed, a common process of change in gap junction function occurred. A transient stimulation of mitosis concomitant with increased apoptosis was also observed during serum deprivation. Gap junctions may play a regulatory role during initiation of these opposite yet equally important mechanisms of maintaining homeostasis. This model system is useful for further studies on the relationships among inter- and intracellular mechanisms of homeostasis.

Health-related quality of life in patients with cataract and glaucoma

The patient's perspective of his or her own health status as it relates to functioning and well-being is referred to as health-related quality of life. Various generic and ophthalmology-specific survey instruments have been used to gain an understanding of patient-oriented health status in patients with cataract or with glaucoma. Improvement in vision-targeted quality of life has been shown following cataract surgery; however, an improvement in self-perceived overall health status following cataract surgery has not been established. Increasing severity of glaucoma has been shown to be negatively related to vision-targeted quality of life; the relationship between increasing severity of glaucoma and overall self-perceived health status is inconclusive. Integration of the concepts of health-related quality of life into clinical practice will require the development of better measurement instruments that can demonstrate notable outcome advantages for patients.

Gap junctions and the regulation of cellular functions of stem cells during development and differentiation

In multicellular organisms, the role of gap junction intercellular communication (GJIC) in the regulation of cell proliferation, cell differentiation, and apoptosis is becoming increasingly recognized as one of the major cellular functions from the start of the fertilized egg, through normal development of the embryo and fetus, to the sexual maturation of the adult and ultimately to the maintenance of health of the aging adult. Given that the function of this membrane-associated protein channel is to synchronize electrotonic or metabolic functions, differential regulation of function at the transcriptional, translational, and posttranslational levels of a family of highly evolutionarily conserved genes (connexins) needs to be considered. Both inherited mutations and environmental modulation of GJIC could, in principle, affect the function of gap junctions to control cell proliferation, cell differentiation, and apoptosis, thereby leading to a wide variety of pathologies. We review a few techniques used to characterize the ability of stem and progenitor cells to perform GJIC.

Ahmed glaucoma valve implant for management of glaucoma in Sturge-Weber syndrome

PURPOSE

To evaluate the safety and efficacy of the Ahmed glaucoma valve implant in patients with glaucoma as a result of Sturge-Weber syndrome.

METHODS

Eleven eyes (10 patients) with glaucoma resulting from Sturge-Weber syndrome had placement of an Ahmed glaucoma valve implant from May 1993 to June 1996 at the Jules Stein Eye Institute. Success was defined by intraocular pressure at the last two consecutive visits of less than 21 mm Hg, no additional glaucoma surgery, no expulsive choroidal hemorrhage, and no retinal detachment.

RESULTS

Mean intraocular pressure on the first postoperative day was 14.0 mm Hg (SD +/- 6.7). The cumulative probability of success was 79% (95% confidence interval [CI], 52% to 100%) at 24 months, 59% (95% CI, 20% to 98%) at 42 months, and 30% (95% CI, 0% to 75%) at 60 months.

CONCLUSIONS

On the basis of limited follow-up, the Ahmed glaucoma valve implant appears to be a relatively useful drainage device in eyes with glaucoma resulting from Sturge-Weber syndrome.

Central nervous system and plasma lipid profiles associated with carteolol and timolol in postmenopausal black women

PURPOSE

Among ocular hypotensive agents, intrinsic sympathomimetic activity (ISA) is unique to carteolol hydrochloride. This study was conducted to evaluate the central nervous system (CNS) and plasma lipid profiles associated with timolol maleate and carteolol hydrochloride in postmenopausal black women with primary open-angle glaucoma (POAG) or ocular hypertension.

METHODS

One hundred subjects met the inclusion and exclusion criteria for this randomized, double-masked, multicenter, parallel-group study. After completion of informed consent and complete ophthalmic examination, eligible patients entered a washout period, during which no topical ophthalmic medications were used. Blood samples were obtained for hematology and blood chemistry evaluations. Vital signs, ocular symptoms, Symptom Checklist-90-R (SCL-90-R) evaluation, intraocular pressure (IOP) measurements, and slit-lamp examinations were performed before randomization to treatment with either topical carteolol hydrochloride 1.0% or topical timolol maleate 0.5%. Patients received active medications twice daily and were monitored at 4 weeks and 12 weeks. At the conclusion of treatment, vital signs, ocular symptoms, SCL-90-R evaluation, IOP, slit-lamp examinations, and blood samples were obtained.

RESULTS

Compared with baseline, high-density lipoprotein (HDL) cholesterol was significantly decreased (worsened) in the timolol group but did not change significantly in the carteolol group. The between-group difference was statistically significant. Total cholesterol to HDL ratio significantly increased (worsened) in the timolol group compared with baseline but did not change in the carteolol group. The difference between groups was statistically significant. No significant differences were observed between groups in SCL-90-R results for either somatization or depression.

CONCLUSIONS

These results suggest that topical carteolol hydrochloride may have a more favorable blood lipid profile than topical timolol maleate in postmenopausal black women with POAG or ocular hypertension. Carteolol and timolol appear to have similar CNS side effect profiles.

Steroid transformations with Fusarium oxysporum var. cubense and Colletotrichum musae

The utility of two locally isolated fungi, pathogenic to banana, for steroid biotransformation has been studied. The deuteromycetes Fusarium oxysporum var. cubense (IMI 326069, UAMH 9013) and Colletotrichum musae (IMI 374528, UAMH 8929) had not been examined previously for this potential. In general, F. oxysporum var. cubense effected 7alpha hydroxylation on 3beta-hydroxy-delta5-steroids, 6beta, 12beta, and 15alpha hydroxylation on steroidal-4-ene-3-ones, side-chain degradation on 17alpha,21-dihydroxypregnene-3,20-diones, and 15alpha hydroxylation on estrone. Both strains were shown to perform redox reactions on alcohols and ketones.

Retrieval analyses of implanted biomaterials: light microscopic and scanning electron microscopic analyses of implants retrieved from humans

We report analyses obtained from 135 implant cases retrieved from humans and submitted to the American Academy of Implant Dentistry Research Foundation--Medical College of Georgia Implant Retrieval Center. The undecalcified samples were embedded in polymethyl-methacrylate and examined with scanning electron microscopy and with routine light via polarized or Nomarski microscopy. Cases included both orthopedic and dental implants as well as entire mandibles obtained at autopsy. Significant numbers of submitted implants had substantial amounts of adhered bone, which permitted evaluation of human bone remodeling to osseointegrated implants. These implants failed because of implant fracture. As has been observed in animal studies, an interdigitating canaliculi network provided communication between interfacial osteocytes and osteocytes deeper within the remodeled osteonal and trabecular bone. Significant numbers of osseointegrated fractured hydroxyapatite-coated dental implants demonstrated the adequate serviceability of these implants prior to biomaterial fracture. In contrast, the hydroxyapatite coating was dissociated from retrieved orthopedic implants, leading to extensive cup loosening and case failure. Caution is advised for the use of hydroxyapatite-coated acetabular implants. This study therefore underscores the need for evaluation of failed human dental and orthopedic implants. Correlations can be drawn between human retrieval and experimental animal studies.

Antiangiogenic therapy targeting the tyrosine kinase receptor for vascular endothelial growth factor receptor inhibits the growth of colon cancer liver metastasis and induces tumor and endothelial cell apoptosis

Increased vascular endothelial growth factor (VEGF) expression is associated with colon cancer metastases. We hypothesized that inhibition of VEGF receptor activity could inhibit colon cancer liver metastases. BALB/c mice underwent splenic injection with CT-26 colon cancer cells to generate metastases. Mice received daily i.p. injections of vehicle, tyrosine kinase inhibitor for Flk-1/KDR (SU5416) or tyrosine kinase inhibitor for VEGF, basic fibroblast growth factor, and platelet-derived growth factor receptors (SU6668). SU5416 and SU6668 respectively inhibited metastases (48.1% and 55.3%), microvessel formation (42.0% and 36.2%), and cell proliferation (24.4% and 27.3%) and increased tumor cell (by 2.6- and 4.3-fold) and endothelial cell (by 18.6- and 81.4-fold) apoptosis (P<0.001). VEGF receptor inhibitors increased endothelial cell apoptosis, suggesting that VEGF may serve as an endothelial survival factor.

Effects of reduced-fat diets consumed ad libitum on intake of nutrients, particularly antioxidant vitamins

OBJECTIVES

To determine whether a reduced-fat diet consumed ad libitum can achieve the recommended intakes of other macronutrients, fiber, and cholesterol and whether such a diet affects intake of other important micronutrients such as fat-soluble vitamins.

DESIGN

Twelve-month, randomized, controlled trial of a reduced-fat, ad libitum diet vs usual diet.

SUBJECTS

One hundred ten adults older than 40 years with glucose intolerance (2-hour blood glucose concentration = 7.0 to 11.0 mmol/L) who were selected from a previous workforce survey.

INTERVENTION

Monthly small-group meetings aimed at identifying sources of dietary fat and ways to reduce fat consumption.

MAIN OUTCOME MEASURES

Nutrient intakes derived from 3-day food diaries at the beginning and end of the study. Blood levels of retinol, alpha-tocopherol, and beta carotene at the end of the study.

STATISTICAL ANALYSES PERFORMED

Unpaired t tests for determining changes in nutrient intake and antioxidant vitamin concentrations. Separate analyses were conducted with users of mineral and vitamin supplements and people who changed smoking status to reduce potential confounding.

RESULTS

Fat intake decreased from 35% to 26% of energy in the reduced-fat diet group compared with a 2% decrease in the control group (P < .0001). Total energy intake also decreased in the 2 groups (-362 vs -59 kcal/day, P < .02). Those changes were reflected in a 3.1 +/- 4.7 kg (mean +/- standard deviation) weight loss in the intervention group compared with a 0.4 +/- 3.0 kg weight gain in the control group (P < .0001). There were no differences between groups in the changes in micronutrient intakes, except for an energy-adjusted increase in beta carotene intake in the reduced-fat diet group. Serum retinol and alpha-tocopherol concentrations were not different between the groups, but the reduced-fat diet group had higher beta carotene concentrations (P = .009).

APPLICATIONS

A reduced-fat, ad libitum diet can be prescribed to improve overall macronutrient intake and achieve modest weight loss without sacrificing micronutrient intakes.

Modes of L929 cell death induced by TNF-alpha and other cytotoxic agents

Recent studies have variably reported that tumour necrosis factor alpha (TNF-alpha) induces either necrosis or apoptosis in L929 cells. This study was undertaken to better characterize the mode of death induced in L929 cells by this agent. We determined the effects of exposure to TNF-alpha and other cytotoxic agents on cell size and morphology, cell membrane permeability, exposure of phosphatidylserine at the cell surface, nuclear morphology and fragmentation of DNA. Our results suggest that L929 cells treated with TNF-alpha alone show nuclear changes and a pattern of DNA fragmentation that are atypical of apoptosis. In contrast, our results demonstrate that, when augmented with actinomycin D, TNF-alpha induces classical apoptosis in L929 cells. We also provide the first report that, in L929 cells, staurosporine induces classical apoptosis and colchicine induces a form of apoptosis lacking internucleosomal DNA fragmentation. Previous studies of TNF-alpha-induced death in L929 cells relied on measurements of only one or two parameters to define the mode of death. Overall, our results suggest that in future cellular or biochemical studies of the effects of TNF-alpha on L929 cells it will be prudent to characterize the mode of death in each case using a multi-parameter approach, as done here.

Follow-up of the original cohort with the Ahmed glaucoma valve implant

PURPOSE

To study the long-term results of the Ahmed glaucoma valve implant in patients with complicated glaucoma in whom short-term results have been reported.

METHODS

In this multicenter study, we analyzed the long-term outcome of a cohort of 60 eyes from 60 patients in whom the Ahmed glaucoma valve was implanted. Failure was characterized by at least one of the following: intraocular pressure greater than 21 mm Hg at both of the last two visits less than 6 mm Hg at both of the last two visits, loss of light perception, additional glaucoma surgery, devastating complications, and removal or replacement of the Ahmed glaucoma valve implant. Devastating complications included chronic hypotony, retinal detachment, malignant glaucoma, endophthalmitis, and phthisis bulbi; we also report results that add corneal complications (corneal decompensation or edema, corneal graft failure) as defining a devastating complication.

RESULTS

The mean follow-up time for the 60 eyes was 30.5 months (range, 2.1 to 63.5). When corneal complications were included in the definition of failure, 26 eyes (43%) were considered failures. Cumulative probabilities of success at 1, 2, 3, and 4 years were 76%, 68%, 54%, and 45%, respectively. When corneal complications were excluded from the definition of failure, 13 eyes (21.5%) were considered failures. Cumulative probabilities of success at 1, 2, 3, and 4 years were 87%, 82%, 76%, and 76%, respectively. Most of the failures after 12 months of postoperative follow-up were because of corneal complications.

CONCLUSIONS

The long-term performance of the Ahmed glaucoma valve implant is comparable to other drainage devices. More than 12 months after the implantation of the Ahmed glaucoma valve implant, the most frequent adverse outcome was corneal decompensation or corneal graft failure. These corneal problems may be secondary to the type of eyes that have drainage devices or to the drainage device itself. Further investigation is needed to identify the reasons that corneal problems follow drainage device implantation.

Mitochondrial DNA regions HVI and HVII population data

Data from 1393 unrelated individuals have been compiled from eight population groups: African Americans, Africans (Sierra Leone), U.S. Caucasians, Austrians, French, Hispanics, Japanese, and Asian Americans. The majority of the mtDNA sequences were observed only once within each population group (i.e., ranging from a low of 60.3% (35/58) of the Asian American sequences to a high of 85.3% (93/109) of the French sequences). Genetic diversity ranged from 0.990 in the African sample to 0.998 in African Americans. Random match probability ranged from 2.50% in the Asian American sample to 0.52% in U.S. Caucasians. The average number of nucleotide differences between individuals in a database is greatest for the African American and African samples (14.1 and 13.1, respectively), and the least variable are the Caucasians (ranging from 7.2 to 8.4). Substitutions are the predominate polymorphism, and at least 92% of the substitutions are transitions. The most prevalent transversions are As substituted for Cs and Cs substituted for As. For most population groups these transversions occurred predominately in the HVI region; however, the African, African American, and Hispanic samples also demonstrated a large portion of their C to A and A to C transversions in the HVII region (at sites 186 and/or 189). Most insertions occur in the HVII region at sites 309.1 and 315.1, within a stretch of C's. Insertions of an additional C are common in all population groups. The sequence data were converted to SSO mtDNA types and compared with population data on Caucasians, Africans, Asians, Japanese, and Mexicans described by Stoneking et al. [M. Stoneking, D. Hedgecock, R.G. Higuchi, L. Vigilant, H.A. Erlich, Population variation of human mtDNA control region sequences detected by enzymatic amplification and sequence-specific oligonucleotide probes, Am. J. Hum. Genet. 48 (1991) 370-382] using an R x C contingency table test. Differences between major population groups (i.e., between African, Caucasian, and Asian) are quite evident, and similar ethnic population groups carried similar SSO polymorphism frequencies. There were only a few SSO types that showed significant differences between subpopulation groups. The SSO data alone can not be used to describe the population genetics with complete sequence data. However, the results of the SSO comparisons are similar to other analyses, and differences in sequence data in regions HVI and HVII are greater between major population groups than between subgroups.

Molecular and Immunologic Characterization of Gynogenetic Channel Catfish (Ictalurus punctatus)

: Second-generation gynogenetic channel catfish were characterized by molecular and immunologic assays to determine if they were isogenic at major histocompatibility complex loci. Southern blot analyses, using channel catfish MHC class II B and class I A gene probes, revealed identical banding patterns among second-generation gynogenetic fish. In contrast, banding patterns from outbred fish differed not only from gynogenetic animals, but also among themselves. Nucleotide sequence analysis of the MHC class II beta(1) domain, which encompasses the peptide binding region, from four randomly selected gynogenetic fish showed a single DNA sequence. In contrast, analysis of the same region from three outbred fish showed sequences that differed not only among themselves, but also from those of gynogenetic animals. In cytotoxic assays, peripheral blood leukocytes from outbred fish lysed both gynogenetic and allogeneic targets, whereas those from gynogenetic fish lysed only allogeneic targets. Taken together, these results suggest that this group of second-generation gynogenetic channel catfish is isogenic at MHC loci and may provide an excellent system with which to study cell-mediated immunity in teleosts.

Polycyclic aromatic hydrocarbons with bay-like regions inhibited gap junctional intercellular communication and stimulated MAPK activity

Many polycyclic aromatic hydrocarbons (PAHs) are known carcinogens. A considerable amount of research has been devoted to predicting the genotoxic, tumor-initiating potential of PAHs based on chemical structure. However, information on the correlation of structure with the non-genetoxic, epigenetic events of tumor promotion is sparse. PAHs containing a bay or bay-like region were shown to be potent inhibitors of gap-junctional intercellular communication (GJIC), an epigenetic event involved in the removal of an initiated cell from growth suppression. We tested the epigenetic toxicity of PAHs containing bay-like regions by comparing the effects of methylated vs. chlorinated isomers of anthracene on the temporal activation of mitogen-activated protein kinase (MAPK) and the regulation of GJIC. Specifically, we used anthracene, 1-methylanthracene, 2-methylanthracene, 9-methylanthracene, 9,10-dimethylanthracene, 1-chloroanthracene, 2-chloroanthracene, and 9-chloroanthracene. We determined the effect of these compounds on GJIC and on the activation of extracellular receptor kinase (ERK 1 and 2), a MAPK, in F344 rat liver epithelial cells. Results showed that bay or bay-like regions, formed by either chlorine or a methyl group, reversibly inhibited GJIC at the same doses, time, and time of recovery, whereas the linear-planar isomers had no effect on GJIC. Similarly, the GJIC-inhibitory isomers also induced the phosphorylation of ERK 1 and ERK 2, while the non-inhibitory isomers had no effect on the activation of these MAPKs. MAPK activation occurred 10-20 min after the inhibition of GJIC, which indicates that MAPK is not involved in the initial regulation of GJIC; instead altered GJIC may be affecting MAPK activation. The present study revealed that there are structural determinants of PAHs, which clearly affect epigenetic events known to be involved in the non-genetoxic steps of tumor promotion. These events are the release of a cell from growth suppression involving the reduction of GJIC, followed by the activation of intracellular mitogenic events.

A reexamination of the role of clusterin as a complement regulator

Clusterin is a highly conserved glycoprotein which has been proposed to protect host cells against complement-mediated cytolysis. We tested the hypothesis that clusterin is a complement regulator using erythrocytes and cells which had been stably transfected with a membrane-anchored form of clusterin as targets for complement-mediated cytolysis. Clusterin gave dose-dependent protection of antibody-coated sheep erythrocytes against complement-mediated lysis by diluted normal human serum. There was a linear relationship between the concentration of clusterin giving 50% protection and the concentration of serum; extrapolation of this to the case of undiluted human serum showed that a clusterin concentration at least two orders of magnitude greater than its physiological plasma concentration would be needed to confer protection against complement-mediated cytolysis under physiological conditions. Physiological concentrations of clusterin did not protect rabbit erythrocytes against alternative complement pathway-mediated lysis using dilute human serum. Exogenous clusterin had no effect on lysis of human erythrocytes triggered by the addition of inulin to autologous human serum. Induction of cell-surface clusterin expression by L929 (murine fibroblast) cells which had been stably transfected with cDNA for human clusterin linked to DNA coding for the 44 C-terminal amino acid residues of CD55 did not protect the cells against complement-mediated lysis by either normal or clusterin-depleted human serum. These data suggest that clusterin may not be a physiologically relevant regulator of complement activation.

Design and evaluation of a ZP3 peptide vaccine in a homologous primate model

The concept of a safe, immunocontraceptive vaccine using the zona pellucida glycoprotein 3 (ZP3) as an immunogen has been marred by the appearance of ovarian dysfunction in several species. However, careful selection of epitopes on mouse ZP3 have demonstrated that it is possible to segregate contraceptive bone marrow-derived (B)-cell epitopes from the cytotoxic thymus-derived (T)-cell epitopes thought to be responsible for inducing ovarian disease. B-cell epitopes on marmoset ZP3 (mstZP3) were identified by epitope mapping studies. Using a panel of polyclonal antibodies against recombinant mstZP3, an immunodominant epitope mstZP3(301-320) was identified. A chimeric peptide was co-linearly synthesized incorporating this sequence with a promiscuous tetanus toxoid T-helper cell epitope. Using the common marmoset (Callithrix jacchus) as an animal model, we have compared the consequences of active immunization with homologous recombinant mstZP3 and mstZP3(301-320) chimeric peptide vaccine. Long-term infertility was achieved using mstZP3 but at the expense of ovarian function. In contrast, no disruption to ovarian function was observed following mstZP3(301-320) immunization. Antibodies to this peptide immunolocalized to the zona pellucida of both marmoset and human ovarian sections and inhibited human sperm-zona binding by approximately 60% in vitro. However, in-vivo studies indicated that targeting a single ZP3 epitope was insufficient to reliably and consistently achieve a contraceptive effect.

MHC class I genes of the channel catfish: sequence analysis and expression

Four cDNAs encoding the major histocompatibility complex (MHC) class I alpha chain were isolated from a channel catfish clonal B-cell cDNA library. Sequence analysis suggests these cDNAs represent three different MHC class I loci. All cDNAs encoded conserved residues characteristic of the MHC class I alpha chain: namely, those involved in peptide binding, salt bridges, disulfide bond formation, and glycosylation. Southern blot analyses of individual outbred and second-generation gynogenetic fish indicated the existence of both polygenic and polymorphic loci. Northern blot studies demonstrated that catfish B, T, and macrophage cell lines transcribed markedly higher levels of class I alpha and beta2-microglobulin (beta2m) mRNA than fibroblast cell lines. In addition, immunoprecipitation data showed that a 41 000 Mr glycoprotein (presumably class I alpha) was associated with beta2m on the surface of catfish B cells. This latter finding is the first direct evidence for the cell surface association of beta2m with the MHC class I alpha chain on teleost cells and supports the notion that functional MHC class I proteins exist in teleosts.

Catfish Oct2 binding affinity and functional preference for octamer motifs, and interaction with OBF-1

The DNA-binding (POU) domain of the catfish Oct2 transcription factor was shown, by electromobility shift assays and surface plasmon resonance techniques, to have an affinity for the consensus octamer motif (ATGCAAAT) that was slightly higher than its affinity for a variant motif (ATGtAAAT). This observation is consistent with the transcriptional activation potentials of catfish Oct2 alpha and Oct2 beta, which were shown to activate transcription in catfish B and T cell lines to an equivalent extent from both the consensus and variant octamer motifs. When tested in a mouse plasmacytoma cell line, catfish Oct2 alpha and Oct2 beta, as well as mouse Oct2, showed higher transcriptional activation with the variant, as compared to the consensus, octamer motif. Catfish Oct2 was shown to function synergistically with the mammalian co-activator, OBF-1, activating octamer-dependent transcription in catfish T cells. The strong transcriptional activity of OBF-1 in catfish cells was dependent on the presence of octamer motif(s) at the proximal (promoter) rather than the distal (enhancer) position.