Mammaglobin B (SCGB2A1) is a novel tumour antigen highly differentially expressed in all major histological types of ovarian cancer: implications for ovarian cancer immunotherapy

Background:

We studied the genetic fingerprints of ovarian cancer and validated the potential of Mammaglobin b (SCGB2A1), one of the top differentially expressed genes found in our analysis, as a novel ovarian tumour rejection antigen.

Methods:

We profiled 70 ovarian carcinomas including 24 serous (OSPC), 15 clear-cell (CC), 24 endometrioid (EAC) and 7 poorly differentiated tumours, and 14 normal human ovarian surface epithelial (HOSE) control cell lines using the Human HG-U133 Plus 2.0 chip (Affymetrix). Quantitative real-time PCR and immunohistochemistry staining techniques were used to validate microarray data at RNA and protein levels for SCGB2A1. Full-length human-recombinant SCGB2A1 was used to pulse monocyte-derived dendritic cells (DCs) to stimulate autologous SCGB2A1-specific cytotoxic T-lymphocyte (CTL) responses against chemo-naive and chemo-resistant autologous ovarian tumours.

Results:

Gene expression profiling identified SCGB2A1 as a top differentially expressed gene in all histological ovarian cancer types tested. The CD8+ CTL populations generated against SCGB2A1 were able to consistently induce lysis of autologous primary (chemo-naive) and metastatic/recurrent (chemo-resistant) target tumour cells expressing SCGB2A1, whereas autologous HLA-identical noncancerous cells were not lysed. Cytotoxicity against autologous tumour cells was significantly inhibited by anti-HLA-class I (W6/32) monoclonal antibody. Intracellular cytokine expression measured by flow cytometry showed a striking type 1 cytokine profile (i.e., high IFN-γ secretion) in SCGB2A1-specific CTLs.

Conclusion:

SCGB2A1 is a top differentially expressed gene in all major histological types of ovarian cancers and may represent a novel and attractive target for the immunotherapy of patients harbouring recurrent disease resistant to chemotherapy.

Epidermal growth factor receptor-directed therapy in esophageal cancer

Esophageal adenocarcinoma (EAC) is one of the fastest growing malignancies in the US. The long-term survival of patients with this cancer remains poor; only 25% of patients undergoing surgical excision are alive after 5 years. Multimodal programs that incorporate radiotherapy, chemotherapy and surgery for localized tumors may result in a modest survival advantage. However, significant strides in this disease can result from the inclusion of targeted therapies. The epidermal growth factor receptor (EGFR) family represents one such target and is receiving increasing attention due to the advent of specific inhibitors. Studies conducted by us and others have shown that the overexpression of EGFR family signaling intermediates is common in Barrett's esophagus and EAC. In the latter case, EGFR expression may have prognostic significance. EGFR inhibitors, including oral tyrosine kinase inhibitors and monoclonal antibodies, result in a synergistic antitumor effect with chemotherapeutic agents or with radiotherapy. Therefore, several ongoing studies include EGFR-directed therapy either alone or in combination with chemoradiotherapy for this disease. Our study of gefitinib, oxaliplatin and radiotherapy suggested that gefitinib can be safely incorporated into an oxaliplatin-based chemoradiation program for esophageal cancer, although the clinical activity of this combination is modest. Herein, we review the current literature on this subject.

Epithelial-mesenchymal transition (EMT) and activated extracellular signal-regulated kinase (p-Erk) in surgically resected pancreatic cancer

BACKGROUND

EMT or transformation to the mesenchymal phenotype plays an important role in tumor invasion and metastasis. In vitro data suggest that mesenchymal transformation may correlate with the activation of PI3 kinase and Ras/Erk pathways. We investigated the expression of EMT markers (low E-cadherin, high fibronectin, and vimentin) and their association with p-Erk in resected pancreatic cancer.

METHODS

Clinical data/surgical specimens from 34 consecutive pancreatic cancer patients (pts) who underwent pancreatectomy were included. Immunohistochemical staining was performed on formalin-fixed paraffin-embedded tissues using monoclonal antibodies against vimentin, fibronectin, E-cadherin, and p-Erk. The results were correlated with clinicopathological parameters and survival. Survival analysis (log-rank test, Cox proportional hazard model), categorical data analysis (Pearson's chi-square, Fisher's exact test) and Kendall's tau were performed at a significance level of 0.05.

RESULTS

The patient population was formed from 13 males and 21 females, with a median age of 66 years (range 38-84 years); American Joint Committee on Cancer (AJCC) stage 1 (n = 2), 2 (n = 27), 3 (n = 5); histological grade 1 (n = 4), 2 (n = 13), 3 (n = 16), 4 (n = 1). Median survival was 15 months (95% CI: 11-24 months). Fibronectin overexpression correlated with the presence of vimentin (p = 0.0048) and activated Erk (p = 0.0264). There was a borderline association of fibronectin with worsening grade (p = 0.06). A negative association between vimentin and E-cadherin was noted (p = 0.0024). Increased fibronectin or vimentin and decreased E-cadherin correlated with poor survival.

CONCLUSION

EMT is associated with poor survival in surgically resected pancreatic adenocarcinoma. A correlation between activated Erk and fibronectin was identified that may open avenues for targeted therapy for this subgroup.

Passive stretching does not protect against acute contraction-induced injury in mouse EDL muscle

A popular part of many athletes pre-game regime is to stretch. We examined whether a pre-injury stretching protocol could prevent acute contraction-induced injury. The in situ extensor digitorum longus (EDL) muscle of an anesthetized mouse (80 mg/kg intra-peritoneal) was used. Damage to the muscle from eccentric contraction-induced injury was quantified by the deficit in tetanic force production, and was not confounded by metabolic fatigue. The force deficits resulting from eccentric contractions alone (E) were compared with the force deficits resulting from a protocol that consisted of a stretch before the eccentric contractions (S + E). The pre-injury stretch was performed to 5% L0 strain, at a velocity of 0.5 mm/s. The muscle was held in the stretch position for 1 min, then slowly released. Eccentric contraction protocols (excursion > or = 24% L0) resulted in pronounced force deficits that increased with the excursion amplitude of the eccentric contraction. The eccentric contractions also resulted in an average right shift of 2 +/- 0.53% in the length-force relationship (t-test, P = 0.0001). The regression lines for the E (eccentric contraction only) and S + E (stretch and eccentric contractions) treatments did not differ from one another for either force deficit (ANCOVA, P = 0.82) or work deficit (ANCOVA, P = 0.12). Therefore, the pre-injury stretch protocol did not reduce the force deficit or the work deficit resulting from contraction-induced injury.

Sp1 and krüppel-like factor family of transcription factors in cell growth regulation and cancer

The Sp/KLF family contains at least twenty identified members which include Sp1-4 and numerous krüppel-like factors. Members of the family bind with varying affinities to sequences designated as 'Sp1 sites' (e.g., GC-boxes, CACCC-boxes, and basic transcription elements). Family members have different transcriptional properties and can modulate each other's activity by a variety of mechanisms. Since cells can express multiple family members, Sp/KLF factors are likely to make up a transcriptional network through which gene expression can be fine-tuned. 'Sp1 site'-dependent transcription can be growth-regulated, and the activity, expression, and/or post-translational modification of multiple family members is altered with cell growth. Furthermore, Sp/KLF factors are involved in many growth-related signal transduction pathways and their overexpression can have positive or negative effects on proliferation. In addition to growth control, Sp/KLF factors have been implicated in apoptosis and angiogenesis; thus, the family is involved in several aspects of tumorigenesis. Consistent with a role in cancer, Sp/KLF factors interact with oncogenes and tumor suppressors, they can be oncogenic themselves, and altered expression of family members has been detected in tumors. Effects of changes in Sp/KLF factors are context-dependent and can appear contradictory. Since these factors act within a network, this diversity of effects may arise from differences in the expression profile of family members in various cells. Thus, it is likely that the properties of the overall network of Sp/KLF factors play a determining role in regulation of cell growth and tumor progression.

Structural weakening of layered acrylic bone cement

Occasionally during arthroplasty procedures, additional cement is required to supplement an initial polymerizing mass. In vitro studies demonstrate that this practice significantly weakens the integrity of the added cement, as determined in mechanical shear. This is accompanied by a marked increase in cement porosity, with the voids acting as sites of stress concentration. This caveat has important consequences in clinical use of acrylic bone cement.

Identification and characterization of human orthologues to Saccharomyces cerevisiae Upf2 protein and Upf3 protein (Caenorhabditis elegans SMG-4)

Nonsense-mediated mRNA decay (NMD), also called mRNA surveillance, is an important pathway used by all organisms that have been tested to degrade mRNAs that prematurely terminate translation and, as a consequence, eliminate the production of aberrant proteins that could be potentially harmful. In mammalian cells, NMD appears to involve splicing-dependent alterations to mRNA as well as ribosome-associated components of the translational apparatus. To date, human (h) Upf1 protein (p) (hUpf1p), a group 1 RNA helicase named after its Saccharomyces cerevisiae orthologue that functions in both translation termination and NMD, has been the only factor shown to be required for NMD in mammalian cells. Here, we describe human orthologues to S. cerevisiae Upf2p and S. cerevisiae Upf3p (Caenorhabditis elegans SMG-4) based on limited amino acid similarities. The existence of these orthologues provides evidence for a higher degree of evolutionary conservation of NMD than previously appreciated. Interestingly, human orthologues to S. cerevisiae Upf3p (C. elegans SMG-4) derive from two genes, one of which is X-linked and both of which generate multiple isoforms due to alternative pre-mRNA splicing. We demonstrate using immunoprecipitations of epitope-tagged proteins transiently produced in HeLa cells that hUpf2p interacts with hUpf1p, hUpf3p-X, and hUpf3p, and we define the domains required for the interactions. Furthermore, we find by using indirect immunofluorescence that hUpf1p is detected only in the cytoplasm, hUpf2p is detected primarily in the cytoplasm, and hUpf3p-X localizes primarily to nuclei. The finding that hUpf3p-X is a shuttling protein provides additional indication that NMD has both nuclear and cytoplasmic components.

Protein kinase C signaling mediates a program of cell cycle withdrawal in the intestinal epithelium

Members of the protein kinase C (PKC) family of signal transduction molecules have been widely implicated in regulation of cell growth and differentiation, although the underlying molecular mechanisms involved remain poorly defined. Using combined in vitro and in vivo intestinal epithelial model systems, we demonstrate that PKC signaling can trigger a coordinated program of molecular events leading to cell cycle withdrawal into G(0). PKC activation in the IEC-18 intestinal crypt cell line resulted in rapid downregulation of D-type cyclins and differential induction of p21(waf1/cip1) and p27(kip1), thus targeting all of the major G(1)/S cyclin-dependent kinase complexes. These events were associated with coordinated alterations in expression and phosphorylation of the pocket proteins p107, pRb, and p130 that drive cells to exit the cell cycle into G(0) as indicated by concomitant downregulation of the DNA licensing factor cdc6. Manipulation of PKC isozyme levels in IEC-18 cells demonstrated that PKCalpha alone can trigger hallmark events of cell cycle withdrawal in intestinal epithelial cells. Notably, analysis of the developmental control of cell cycle regulatory molecules along the crypt-villus axis revealed that PKCalpha activation is appropriately positioned within intestinal crypts to trigger this program of cell cycle exit-specific events in situ. Together, these data point to PKCalpha as a key regulator of cell cycle withdrawal in the intestinal epithelium.

Protein kinase C-mediated regulation of the cell cycle

Members of the protein kinase C (PKC) family of signal transduction molecules have been widely implicated in regulation of cell growth/cell cycle progression and differentiation. Increasing evidence from studies using in vitro and in vivo systems points to PKC as a key regulator of critical cell cycle transitions, including cell cycle entry and exit and the G1 and G2 checkpoints. PKC-mediated control of these transitions can be negative or positive, depending on the timing of PKC activation during the cell cycle and on the specific PKC isozymes involved. Most of the mechanistic information available relates to the involvement of this enzyme family in negative regulation of these transitions. Accumulating data indicate that a major target for PKC-mediated inhibition of cell cycle progression is the Cip/Kip cyclin-dependent kinase (cdk) inhibitor p21waf1/cip1. Increased expression of p21waf1/cip1 blocks cdk2 activity in G1 phase, leading to hypophosphorylation of the retinoblastoma protein and inhibition of cell cycle progression into S phase. In G2, p21waf1/cip1 expression blocks cdc2/cyclin B activity, likely through an indirect mechanism involving inhibition of the cdk2/cyclin A complex, and prevents progression into M phase. PKC signaling can also activate a coordinated program of pocket protein regulation leading to cell cycle withdrawal into G0. The molecular events underlying positive regulation of cell cycle progression by PKC signaling remain poorly understood, although there is evidence for a role of the enzyme in promoting G2(r)M progression by phosphorylating lamin B at sites involved in nuclear lamina disassembly. Understanding of the mechanisms underlying PKC-mediated control of the cell cycle is beginning to provide important insight into its role in uncontrolled cell growth and transformation.

Nonintrusive optical measurements of aircraft engine exhaust emissions and comparison with standard intrusive techniques

Nonintrusive systems for the measurement on test rigs of aeroengine exhaust emissions required for engine certification (CO, NO(x), total unburned hydrocarbon, and smoke), together with CO(2) and temperature have been developed. These results have been compared with current certified intrusive measurements on an engine test. A spectroscopic database and data-analysis software has been developed to enable Fourier-transform Infrared measurement of concentrations of molecular species. CO(2), CO, and NO data showed agreement with intrusive techniques of approximately ?30%. A narrow-band spectroscopic device was used to measure CO(2) (with deviations of less than ?10% from the intrusive measurement), whereas laser-induced incandescence was used to measure particles. Future improvements to allow for the commercial use of the nonintrusive systems have been identified and the methods are applicable to any measurement of combustion emissions.

Polarized expression of immunoglobulin, spectrin, and protein kinase C beta II occurs in B cells from normal BALB/c, autoimmune lpr, and anti-ssDNA transgenic, tolerant mice

The rapid redistribution of B cell surface immunoglobulin to a cap upon cross-linking treatment is a well-described phenomenon, the physiological significance of which is unknown. We describe the observation that splenic B cells from unimmunized normal, autoimmune, and tolerant mice express naturally occurring capped immunoglobulin in the absence of exogenous stimulation. The percentage of capped B cells increases to 20% of B cells by age 16 weeks in the progressive autoimmune lpr mouse. Transgenic, tolerant mice expressing lpr-derived genes for ssDNA-binding antibody also demonstrate a large percentage (35-75%) of immunoglobulin-capped splenic B cells. In these capped B cells, protein kinase C beta II, the cytoskeletal proteins spectrin and ankyrin, and the lipophilic probe diI are enriched beneath the site of the immunoglobulin cap. These data suggest that polarization of surface receptors, signaling molecules, anionic phospholipid domains, and cytoskeletal proteins may be an important part of the B cell immune response in vivo.

Polyamine analogue induction of the p53-p21WAF1/CIP1-Rb pathway and G1 arrest in human melanoma cells

Although polyamines are well recognized for their critical involvement in cell growth, the cell cycle specificity of this requirement has not yet been characterized with respect to the newly delineated regulatory pathways. We recently reported that polyamine analogues having close structural and functional similarities to the natural polyamines produce a distinct G1 and G2-M cell cycle arrest in MALME-3M human melanoma cells. To determine a molecular basis for this observation, we examined the effects of N1,N11-diethylnorspermine on cell cycle regulatory proteins associated with G1 arrest. The analogue is known to deplete polyamine pools by suppressing biosynthetic enzymes and potently inducing the polyamine catabolic enzyme spermidine/spermine N1-acetyltransferase. Treatment of MALME-3M cells with 10 microM N1,N11-diethylnorspermine caused an increase in hypophosphorylated Rb, which correlated temporally with the onset of G1 arrest at 16-24 h. Rb hypophosphorylation was preceded by an increase in wild-type p53 (approximately 100-fold at maximum) and a concomitant increase in the cyclin-dependent kinase inhibitor, p21WAF1/CIP1 (p21; approximately 5-fold at maximum). Another cyclin-dependent kinase inhibitor, p27KIP1, and cyclin D increased slightly, whereas proliferating cell nuclear antigen and p130 remained unchanged. Induction of p21 protein was accompanied by an increase in p21 mRNA, whereas induction of p53 protein was not, suggesting transcriptional activation of the former and posttranscriptional regulation of the latter. SK-MEL-28 human melanoma cells, which contain a mutated p53, failed to induce p53 or p21 and did not arrest in G1. Rather, these cells rapidly underwent programmed cell death within 48 h. Overall, these findings provide the first indication of the cell cycle regulatory pathways by which polyamine antagonists such as analogues might inhibit growth in cells containing wild-type p53 and further suggest a mechanistic basis for differential cellular responses to these agents.

Dynamic association of L-selectin with the lymphocyte cytoskeletal matrix

L-selectin mediates lymphocyte extravasation into lymphoid tissues through binding to sialomucin-like receptors on the surface of high endothelial venules (HEV). This study examines the biochemical basis and regulation of interactions between L-selectin, an integral transmembrane protein, and the lymphocyte cytoskeleton. Using a detergent-based extraction procedure, constitutive associations between L-selectin and the insoluble cytoskeletal matrix could not be detected. However, engagement of the L-selectin lectin domain by Abs or by glycosylation-dependent cell adhesion molecule-1, an HEV-derived ligand for L-selectin, rapidly triggered redistribution of L-selectin to the detergent-insoluble cytoskeleton. L-selectin attachment to the cytoskeleton was not prevented by inhibitors of actin/microtubule polymerization (cytochalasin B, colchicine, or nocodozole) or serine/threonine and tyrosine kinase activity (staurosporine, calphostin C, or genistein), although L-selectin-mediated adhesion of human PBL was markedly suppressed by these agents. Exposure of human PBL or murine pre-B transfectants expressing full-length human L-selectin to fever-range hyperthermia also markedly increased L-selectin association with the cytoskeleton, directly correlating with enhanced L-selectin-mediated adhesion. In contrast, a deletion mutant of L-selectin lacking the COOH-terminal 11 amino acids failed to associate with the cytoskeletal matrix in response to Ab cross-linking or hyperthermia stimulation and did not support adhesion to HEV. These studies, when taken together with the previously demonstrated interaction between the L-selectin cytoplasmic domain and the cytoskeletal linker protein alpha-actinin, strongly implicate the actin-based cytoskeleton in dynamically controlling L-selectin adhesion.

Lysosomal sequestration of polyamine analogues in Chinese hamster ovary cells resistant to the S-adenosylmethionine decarboxylase inhibitor, CGP-48664

CGP-48664, an inhibitor of the polyamine biosynthetic enzyme S-adenosylmethionine decarboxylase (AdoMetDC), is presently undergoing Phase 1 clinical trials as an experimental anticancer agent. We have shown previously (D. L. Kramer et al., J. Biol. Chem., 270: 2124-2132, 1995) that Chinese hamster ovary (CHO) cells that are made resistant to the growth inhibitory effects of the drug overexpress AdoMetDC because of a stable gene amplification. Unexpectedly, these same cells (CHO/644) were found to be insensitive to the growth inhibitory effects of N1,N11-diethylnorspermine (DENSPM)-a polyamine analogue also undergoing Phase 1 clinical trials-despite accumulating approximately 5 times more analogue than parental cells. We now report that treatment of CHO/664 cells with DENSPM results in the formation of numerous large cytoplasmic vacuoles, which on the basis of electron microscopy and cytochemical staining seem to be lysosomal in origin. A series of newly established CHO cell lines made differentially resistant to 1, 3, 10, 30, and 100 microM CGP-48664 by chronic exposure were used to demonstrate that vacuole formation correlated with the accumulation of extremely high levels of DENSPM without increasing growth inhibition. These same cells were used to show that AdoMetDC gene overexpression as indicated by mRNA levels was unrelated to vacuole formation; cells resistant to 100 microM CGP-48664 displayed a 170-fold increase in AdoMetDC mRNA levels and formed vacuoles in response to DENSPM, whereas those resistant to 10 microM CGP-48664 displayed a 120-fold increase in AdoMetDC mRNA levels and failed to form vacuoles. Despite accumulating to high intracellular levels, DENSPM was much less effective than spermine at down-regulating ornithine decarboxylase and polyamine transport activities in highly resistant cells. Similarly, DENSPM was less able to induce spermidine/spermine N1-acetyltransferase activity in cells that formed vacuoles than in those that did not. Overall, natural polyamines failed to induce vacuoles and various analogues of DENSPM were used to probe the structural specificity of the effect. The data are consistent with the probability that DENSPM is sequestered to high concentrations in lysosomal vacuoles of CGP-48664-resistant cells and is, therefore, not available to interact with polyamine regulatory sites or to cytotoxically affect cell growth. In addition to implicating the lysosome as a potential new site of CGP-48664 drug action that could be involved in antitumor activity and/or host toxicities, the findings also suggest a potential mechanism of cell resistance to analogues such as DENSPM.

Interleukin 15 offers selective protection from irinotecan-induced intestinal toxicity in a preclinical animal model

Irinotecan (CPT-11) is a chemotherapeutic agent that is active in the treatment of a variety of solid tumor malignancies. Diarrhea represents the most common dose-limiting toxicity that is independent of the schedule of administration. A rat model with dose-limiting toxicity profiles that are similar to those observed in patients treated with CPT-11 was developed and used to evaluate the role of interleukin 15 (IL-15) in the modulation of the therapeutic selectivity of CPT-11 in normal rats and rats bearing advanced colorectal cancer. The maximum tolerated dose and lethal dose (LD) of CPT-11 by i.v. push daily x 3 were 150 and 200 mg/kg/day, respectively. CPT-11 at the LD induced a 93-100% incidence of severe diarrhea and an 86-100% incidence of lethality in treated animals. IL-15, a cytokine with multiple mechanisms of action, was used at a 100 or 400 microg/kg/dose with different schedules of administration (3, 8, and 11 doses, i.p.) to protect against CPT-11-induced toxicity. IL-15 offered complete and sustained selective protection against CPT-11-induced delayed diarrhea and lethality. IL-15 also moderately potentiated the antitumor activity of CPT-11 in rats bearing advanced colorectal cancer. Morphological examination of rat intestinal tissues after treatment with LD of CPT-11 revealed dramatic protection of duodenal and colonic tissue architecture by IL-15. CPT-11 alone produced serious damage to duodenal villi and colonic crypts. The results clearly demonstrated the ability of IL-15 to provide significant protection from CPT-11-induced intestinal toxicity with maintenance of antitumor activity, resulting in an increase in the therapeutic index of CPT-11. The clinical relevance of the results obtained in this model system needs to be confirmed.

Colonocyte differentiation is associated with increased expression and altered distribution of protein kinase C isozymes

BACKGROUND & AIMS

Colon cancer cells express reduced levels of protein kinase C (PKC). This study examines the regulation of PKC isozymes in normal colonic epithelium, as a basis for understanding the significance of alterations in this enzyme system in colon carcinogenesis.

METHODS

The expression and localization of PKC isozymes in mouse and rat colonocytes at different developmental stages were determined using a combined morphological and biochemical approach. PKC alpha expression was compared in colonic adenocarcinomas and adjacent normal mucosa by immunoblot analysis.

RESULTS

Mouse and rat colonocytes express PKC alpha, beta II, delta, epsilon, and zeta. Relatively low levels of these isozymes were detected in proliferating cells of the crypt base, predominantly in the cytosolic compartment. Coincident with colonocyte growth arrest/differentiation, PKC isozyme expression markedly increased in both the cytosolic and, more significantly, in the membrane/cytoskeletal fraction. Colonic tumors express reduced levels of PKC alpha, an isozyme that has been implicated in negative control of intestinal cell growth.

CONCLUSIONS

These findings are supportive of a role for certain PKC isozyme(s) in signaling pathways mediating postmitotic events in colonocytes in situ, and suggest that diminished activity of these pathway(s) may contribute to the alterations in growth control/differentiation associated with colonic neoplasia.

Protein kinase C isozyme-mediated cell cycle arrest involves induction of p21(waf1/cip1) and p27(kip1) and hypophosphorylation of the retinoblastoma protein in intestinal epithelial cells

The molecular mechanisms underlying protein kinase C (PKC) isozyme-mediated control of cell growth and cell cycle progression are poorly understood. Our previous analysis of PKC isozyme regulation in the intestinal epithelium in situ revealed that multiple members of the PKC family undergo changes in expression and subcellular distribution precisely as the cells cease proliferating in the mid-crypt region, suggesting that activation of one or more of these molecules is involved in negative regulation of cell growth in this system (Saxon, M. L., Zhao, X., and Black, J. D. (1994) J. Cell Biol. 126, 747-763). In the present study, the role of PKC isozyme(s) in control of intestinal epithelial cell growth and cell cycle progression was examined directly using the IEC-18 immature crypt cell line as a model system. Treatment of IEC-18 cells with PKC agonists resulted in translocation of PKC alpha, delta, and epsilon from the soluble to the particulate subcellular fraction, cell cycle arrest in G1 phase, and delayed transit through S and/or G2/M phases. PKC-mediated cell cycle arrest in G1 was accompanied by accumulation of the hypophosphorylated, growth-suppressive form of the retinoblastoma protein and induction of the cyclin-dependent kinase inhibitors p21(waf1/cip1) and p27(kip1). Reversal of these cell cycle regulatory effects was coincident with activator-induced down-regulation of PKC alpha, delta, and epsilon. Differential down-regulation of individual PKC isozymes revealed that PKC alpha in particular is sufficient to mediate cell cycle arrest by PKC agonists in this system. Taken together, the data implicate PKC alpha in negative regulation of intestinal epithelial cell growth both in vitro and in situ via pathways which involve modulation of Cip/Kip family cyclin-dependent kinase inhibitors and the retinoblastoma growth suppressor protein.

The relationship between smoking exposure and p53 overexpression in colorectal cancer

Although epidemiological studies of the relationship between cigarette smoking and colorectal cancer risk have been equivocal, a positive association is consistently found for colorectal adenoma development. We performed an epidemiological study to determine whether p53 protein overexpression, in tumours obtained at the time of resection, is associated with cigarette exposure in colorectal cancer. A total of 163 colorectal cancer cases and 326 healthy controls responded to a standardised questionnaire on colorectal cancer risk factors including detailed information on their history of cigarette smoking. All patients' tumours were analysed immunohistochemically for p53 overexpression using an avidin-biotin immunoperoxidase procedure and polyclonal anti-p53 antibody CM1. Comparison of colorectal cases with controls revealed an elevated risk for ex-smokers (OR = 1.34, 95% CI 0.85-2.12) and current smokers (OR = 1.13, 95% CI 0.63-2.02) when compared with non-smokers. No dose-response relationship was found for total pack-years of smoking (trend test: P = 0.19). However, a trend for total pack-years of smoking was found when p53-positive cases were compared with p53-negative cases suggesting aetiological, heterogeneity (trend test: P = 0.06). Estimating the individual relative risk of developing a p53-positive tumour relative to controls showed no associations for smoking status or total pack-years of smoking. However, when p53-negative cases were compared with controls, an elevated risk was found for ex-smokers (OR = 1.84, 95% CI 1.00-3.37) and current years of smoking (trend test: P = 0.03). Colorectal tumours developing through p53-positive dependent pathways were not associated with smoking exposure. A significant increase in risk was observed for the p53-negative independent pathway with smoking. p53 overexpression appears to be associated with smoking exposure in colorectal cancer.

Familial and nutritional risk factors for p53 overexpression in colorectal cancer

Although familial and dietary factors are recognized as important risk determinants for colorectal tumorigenesis, the specific causes of colorectal cancer remain unclear. Studies of p53 genetic alterations have provided clues concerning the etiology of many cancers. This study was designed to determine whether overexpression of the p53 protein is associated with familial and dietary risk factors. Epidemiological data were obtained from 163 colorectal cancer cases and 326 healthy controls. Tumors of all patients were analyzed immunohistochemically for p53 overexpression using an avidin-biotin immunoperoxidase procedure and polyclonal anti-p53 antibody CM1. Of patient tumors, 44.8% showed p53 nuclear reactivity. Colorectal cases versus controls were three times more likely to report a family history of colorectal cancer [odds ratio (OR), 3.12; 95% confidence interval (CI), 1.77-5.52]. Only cruciferous vegetables exhibited a significant inverse association (OR, 0.59; 95% CI, 0.34-1.02; trend test, P = 0.03) for the highest versus lowest quartiles. Both meat and beef displayed an elevated increase in risk. When cases with p53 overexpression (p53 positive) were compared with cases without p53 overexpression (p53 negative), etiological heterogeneity was suggested for family history of colorectal cancer (OR, 0.39; 95% CI, 0.16-0.93), cruciferous vegetables (trend test, P = 0.12), and beef consumption (trend test, P = 0.08). To estimate the individual relative risks for p53-dependent and p53-independent pathways, each p53 subtype was compared with controls. Cruciferous vegetables exhibited a significant association (OR, 0.37; 95% CI, 0.17-0.82; trend test, P = 0.03) when p53 positive cases were compared with controls. When p53 negative cases were compared with controls, a significant increase in risk was observed for family history of cancer (OR, 4.46; 95% CI, 2.36-8.43) and beef (OR, 3.17; 95% CI, 1.83-11.28; trend test, P = 0.006). The p53 (positive) dependent pathway was characterized by an inverse association with cruciferous vegetables, and p53-independent tumors were characterized by family history and beef consumption. These data may indicate the significance of linking epidemiology and molecular biology in assessing specific etiological pathways.

Prolactin and epidermal growth factor regulation of the proliferation, morphogenesis, and functional differentiation of normal rat mammary epithelial cells in three dimensional primary culture

The epithelial cell-specific effects of prolactin and epidermal growth factor (EGF) on the development of normal rat mammary epithelial cells (MEC) were evaluated using a three dimensional primary culture model developed in our laboratory. Non-milk-producing MEC were isolated as spherical end bud-like mammary epithelial organoids (MEO) from pubescent virgin female rats. The cultured MEO developed into elaborate multilobular and lobuloductal alveolar organoids composed of cytologically and functionally differentiated MEC. Prolactin (0.01-10 micrograms/ml) and EGF (1-100 ng/ml) were each required for induction of cell growth, extensive alveolar, as well as multilobular branching morphogenesis, and casein accumulation. MEO cultured without prolactin for 14 days remained sensitive to the mitogenic, morphogenic, and lactogenic effects of prolactin upon subsequent exposure. Similarly, cells cultured in the absence of EGF remained sensitive to the mitogenic and lactogenic effects of EGF, but were less responsive to its morphogenic effects when it was added on day 14 of a 21-day culture period. If exposure to prolactin was terminated after the first week, the magnitude of the mitogenic and lactogenic effects, but not the morphogenic response was decreased. Removal of EGF on day 7 also reduced the mitogenic response, but did not have any effect on the magnitude of the lactogenic or morphogenic responses. These studies demonstrate that physiologically relevant development of normal MEC can be induced in culture and that this model system can be used to study the mechanisms by which prolactin and EGF regulate the complex developmental pathways operative in the mammary gland.

The effects of lasers and electrosurgical devices on human meniscal tissue

The purpose of this study was to evaluate the effects of various laser wavelengths on human meniscal tissue in vitro and to compare them with the effects of electrosurgical devices. The carbon dioxide (CO2) laser produced the best cutting and ablating effects among the infrared lasers, although the contact neodymium:yttrium-aluminum-garnet (Nd:YAG) and holmium:YAG (Ho:YAG)lasers were nearly as satisfactory, offering the additional advantage of fiberoptic capability and the ability to be used in saline. The free-beam Nd:YAG laser and coagulation mode electrosurgical device produced unacceptably severe thermal changes. The excimer laser at 308 nm produced the best tissue effect and caused no detectable adjacent thermal change in the tissue.

Developmental regulation of beta-galactoside alpha 2,6-sialyltransferase in small intestine epithelium

A striking biochemical alteration to the epithelium of the small intestine upon weaning is the loss of microvillar sialic acids. Antibody and cDNA probes to the beta-galactoside alpha 2,6-sialyltransferase (SiaT-1, EC 2.4.99.1) were used to characterize the expression of this sialyltransferase in the small intestine of suckling rats. SiaT-1 mRNA and protein in the intestinal epithelium are rapidly lost upon weaning, in agreement with the loss of mucosal sialic acids and general sialyltransferase activity. Developmental repression of SiaT-1 is manifested in a proximal to distal gradient; SiaT-1 mRNA and protein are lost first from the duodenum and persist the longest in the ileum. We have previously documented that SiaT-1 gene expression can be transcriptionally initiated from a number of distinct tissue-specific promoter regions. Here, by criteria of mRNA mobility on agarose gels, primer extension analysis, and differential Northern hybridization, we show that the promoter previously considered to be liver-specific is operative in SiaT-1 expression in the small intestine of suckling animals. Comparison of this SiaT-1 promoter region with promoter regions of other genes exhibiting dual intestine-hepatic tissue specificity revealed a number of striking sequence similarities. Regulatory implications and consequences of small intestinal SiaT-1 expression in suckling but not in weaned animals are discussed.

Activation of protein kinase C isozymes is associated with post-mitotic events in intestinal epithelial cells in situ

The mechanisms underlying control of cell growth and differentiation in epithelial tissues are poorly understood. Protein kinase C (PKC) isozymes, members of a large family of serine/threonine kinases of fundamental importance in signal transduction, have been increasingly implicated in the regulation of cell growth, differentiation, and function. Using the rat intestinal epithelium as a model system, we have examined PKC-specific activity as well as individual PKC isozyme expression and distribution (i.e., activation status) in epithelial cells in situ. Increased PKC activity was detected in differentiating and functional cells relative to immature proliferating crypt cells. Immunofluorescence and Western blot analysis using a panel of isozyme-specific antibodies revealed that PKC alpha, beta II, delta, epsilon, and zeta are expressed in rat intestinal epithelial cells and exhibit distinct subcellular distribution patterns along the crypt-villus unit. The combined morphological and biochemical approach used permitted analysis of the activation status of specific PKC isozymes at the individual cell level. These studies showed that marked changes in membrane association and level of expression for PKC alpha, beta II, delta, and zeta occur as cells cease division in the mid-crypt region and begin differentiation. Additional changes in PKC activation status are observed with acquisition of mature function on the villus. These studies clearly demonstrate naturally occurring alterations in PKC isozyme activation status at the individual cell level within the context of a developing tissue. Direct activation of PKC in an immature intestinal crypt cell line was shown to result in growth inhibition and coincident translocation of PKC alpha from the cytosolic to the particulate subcellular fraction, paralleling observations made in situ and providing further support for a role of intestinal PKC isozymes in post-mitotic events. PKC isozymes were also found to be tightly associated with cytoskeletal elements, suggesting participation in control of the structural organization of the enterocyte. Taken together, the results presented strongly suggest an involvement of PKC isoforms in cellular processes related to growth cessation, differentiation, and function of intestinal epithelial cells in situ.

Dynamic properties of ankyrin in T lymphocytes: colocalization with spectrin and protein kinase C beta

Ankyrin is a well characterized membrane skeletal protein which has been implicated in the anchorage of specific integral membrane proteins to the spectrin-based membrane skeleton in a number of systems. In this study, the organization of ankyrin was examined in lymphocytes in relation to T cell function. Light and electron microscope immunolocalization studies revealed extensive heterogeneity in the subcellular distribution of ankyrin in murine tissue-derived lymphocytes. While ankyrin can be localized at the lymphocyte plasma membrane, it can also be accumulated at some distance from the cell periphery, in small patches or in a single discrete, nonmembrane-bound structure. Double immunofluorescence studies demonstrated that ankyrin colocalizes with spectrin and with the signal transducing molecule protein kinase C beta (PKC beta) in tissue-derived lymphocytes, suggesting a functional association between these molecules in the lymphocyte cytoplasm. In addition, T lymphocyte activation-related signals and phorbol ester treatment, both of which lead to PKC activation, cause a rapid translocation of ankyrin, together with spectrin and PKC beta, to a single Triton X-100-insoluble aggregate in the cytoplasm. This finding suggests a mechanism for the reported appearance of PKC in the particulate fraction of cells after activation: activated lymphocyte PKC beta may interact with insoluble cytoskeletal elements like ankyrin and spectrin. Further evidence for a link between the subcellular organization of these proteins and PKC activity is provided by the observation that inhibitors of PKC activity cause their concomitant redistribution to the cell periphery. The dynamic nature of lymphocyte ankyrin and its ability to accumulate at sites distant from the plasma membrane are properties which may be unique to the lymphocyte form of the molecule. Its colocalization with PKC beta in the lymphocyte cytoplasm, together with its redistribution in response to physiological signals, suggests that structural protein(s) may play a role in signal transduction pathways in this cell type. Our data support the conclusion that ankyrin is not solely involved in anchorage of proteins at the plasma membrane in lymphoid cells.

Laser arthroscopy

Lasers have become widely used in several medical and surgical disciplines. In ophthalmology and plastic surgery, their use has permitted the development of therapeutic modalities that would have been otherwise impossible. In such specialties as gynecology and general surgery, lasers provide advantages that make certain procedures more convenient and easier to perform. In contrast, orthopaedic surgeons have, to date, been slow to accept these devices into the therapeutic armamentarium. The purpose of this paper is to describe the status of laser use in the orthopaedic subspecialty of arthroscopy.

Rotational coherent anti-stokes Raman spectroscopy measurements in a rotating cavity with axial throughflow of cooling air: oxygen concentration measurements

In a rotating cavity rig, which models cooling air flow in the spaces between disks of a gas turbine compressor, the buildup of oxygen concentration after the cooling gas was changed from nitrogen to air was monitored using rotational coherent anti-Stokes Raman spectroscopy (CARS). From this information an estimate of the fraction of the throughflow entering the rotating cavity was obtained. This demonstrates that rotational CARS can be applied as a nonintrusive concentration-measurement technique in a rotating engineering test rig.

Growth of human renal cortical tissue on collagen gel

A model system for 3-dimensional "native-state" culture of tissues on collagen gels (Proc. Natl. Acad. Sci. USA 86:2013-2017; 1989) has been applied in this study to histologically normal human renal cortical tissue from 11 patients undergoing nephrectomy for renal cell carcinoma elsewhere in the kidney. Microbial contamination occurred in 12/90 cultures, the rest (78) were studied by visual inspection, histology, immunohistochemical analysis for pankeratin (epithelial cell origin), vimentin (mesenchymal cell origin), and p-glycoprotein (associated with proximal tubules), transmission electron microscopy (EM), incorporation of tritiated thymidine (3HTdR). In the first 10 days, explants showed 3HTdR-labeled cells in tubule structures. The surrounding gel was invaded by cells forming tubule structures, sometimes with basement membrane. Some of these cells showed labeling by 3HTdR and immunostaining positive for pankeratin and p-glycoprotein. EM showed well-polarized epithelial cells in tubule structures with tight junctions, interdigitating lateral processes, and microvilli characteristic of proximal and distal convoluted tubules. 3HTdR-labeled cells in tubule structures were observed even 2 mo. after Passage 1, 6 mo. after the initial explantation. Tubule growth was most active and fibroblast proliferation was negligible from 2 to 4 wk postexplantation. The proliferation of tubulelike cells and formation of tubulelike structures in this system represents an opportunity to study human renal cortical tissue in vitro, under conditions more closely resembling in vivo circumstances than are present in other in vitro systems suitable for long-term study. This model has potential use for in vitro toxicology studies and studies of renal physiology.

Mammary organoids from immature virgin rats undergo ductal and alveolar morphogenesis when grown within a reconstituted basement membrane

We have recently described a primary culture system which allows for extensive proliferation and functional differentiation of immature mammary epithelial cells. Herein, these findings are extended to demonstrate that a distinct pattern of ductal and alveolar morphogenesis can be induced within the mammary organoids isolated from virgin female rats and cultured within an Engelbreth-Holm-Swarm sarcoma-derived reconstituted basement membrane under defined serum-free conditions. The lobular and multilobular organoids that emerged resemble the alveoli of the mammary gland in gross form, multicellular architecture, and cytologic and functional differentiation, while the ductal organoids expressed characteristics typical of mammary gland ducts in vivo. The epithelial cells within the alveolar- and duct-like organoids displayed the capability of secreting two morphologically distinct milk products, casein and lipid, into the luminal compartment. The expression of histiotypic morphogenesis and mammary-specific functional differentiation by the cultured mammary organoids proceeded in the absence of a morphologically distinct basal lamina. We illustrate that development highly reminiscent of that which naturally occurs in the mammary gland in vivo can be induced and supported in vitro under defined serum-free conditions. In addition, the methodologies are available to simultaneously monitor mammary organoid morphogenesis, growth, and functional differentiation. This system should serve as a unique model in which the regulation of branching morphogenesis, development, gene expression, and transformation can be examined.

Primary culture of normal rat mammary epithelial cells within a basement membrane matrix. II. Functional differentiation under serum-free conditions

A serum-free primary culture system is described which allows normal rat mammary epithelial cells (RMECs) embedded within a reconstituted basement membrane to undergo extensive growth and functional differentiation as detected by synthesis and secretion of the milk products casein and lipid. RMECs isolated from mammary glands of immature virgin rats were seeded within an extracellular matrix preparation derived from the Engelbreth-Holm-Swarm sarcoma and cultured in a serum-free medium consisting of Dulbecco's modified Eagle's medium-F12 containing insulin, prolactin, progesterone, hydrocortisone, epidermal growth factor, bovine serum albumin, transferrin, and ascorbic acid. Casein synthesis and secretion were documented at the electron microscopic level as well as by an enzyme-linked immunosorbent assay (ELISA) assay using a polyclonal antibody against total rat caseins. Numerous secretory vesicles with casein micelles were noted near the apical surface of the RMECs, and secreted casein was observed in the lumen. These ultrastructural data were confirmed by the ELISA assay which showed that microgram amounts of casein per well were synthesized by the RMECs and that the amount of casein increased with time in culture. Using immunoblot analysis it was demonstrated that the full complement of casein proteins was synthesized. In addition to casein protein, beta-casein mRNA levels were shown to increase with time. Synthesized lipid was detected at both the light and electron microscopic levels. Phase contrast photomicrographs demonstrated extensive intracellular lipid accumulation within the ductal and lobuloalveolarlike colonies, and at the electron micrograph level, lipid droplets were predominantly localized near the apical surface of the RMECs. The lipid nature of these droplets was verified by oil red O staining. Results from this study demonstrate that RMECs from immature virgin rats proliferate extensively and rapidly develop the capacity to synthesize and secrete casein and lipid when grown within a reconstituted basement membrane under defined serum-free conditions. This unique system should thus serve as an excellent model in which the regulation of mammary development and gene expression can be investigated.

Activation induces a rapid reorganization of spectrin in lymphocytes

Lymphocyte activation results in a rapid reorganization of the cytoskeletal protein spectrin. Immediately following an activation signal, there is fragmentation of a spectrin-rich cytoplasmic structure and subsequent translocation of the fragments to defined areas of the plasma membrane in both antigen-specific T cell hybridomas and lymph node T cells. These dramatic changes have been documented by light and electron microscopic immunolocalization and by immunoblot analysis of plasma membrane-enriched preparations. A T cell hybridoma variant lacking the spectrin-rich cytoplasmic structure of the parental line does not redistribute spectrin and produces little or no IL-2 in response to antigen-dependent activation. This suggests a functional link between spectrin distribution and activation potential. We propose that the cytoplasmic structure functions as an organizing center or reservoir for spectrin that is sensitive to signaling at the cell surface.

Heterogeneity in lymphocyte spectrin distribution: ultrastructural identification of a new spectrin-rich cytoplasmic structure

Spectrin-like proteins are found in a wide variety of non-erythroid cells where they generally occur in the cell cortex near the plasma membrane. To determine the intracellular distribution of alpha-spectrin (alpha-fodrin) in lymphocytes, we have developed an immunoperoxidase method to localize this protein at the ultrastructural level. Of considerable interest, particularly with regard to our efforts to determine the function of spectrin in this cell type, was the finding that its subcellular localization and its relationship with the plasma membrane can vary dramatically. Based on its position in the cell, alpha-spectrin can occur in two forms in lymphocytes: one that associates closely with the plasma membrane and another that occurs at some distance from the cell periphery, either as a single large aggregate or as several smaller ones. The single large aggregate of spectrin is a stable feature in a number of lymphocyte cell lines and hybrids which were used to examine its ultrastructural characteristics. A previously undescribed cellular structure, consisting of a meshwork of spectrin filaments and membranous vesicles, was identified in these cells. This structure could be induced to dissipate in response to membrane perturbants (e.g., hyperthermia and phorbol esters, known effectors of lymphocyte function and differentiation) and the patterns resulting from the redistribution of spectrin were a reflection of those observed routinely in lymphocytes in situ. The correlation between naturally occurring spectrin localization patterns and those seen after membrane perturbation suggested the possibility that spectrin distribution is indicative of particular maturation stages or functional states in lymphocytes. The implications of these findings with regard to the role of spectrin in lymphocyte function are discussed.

Selective location of acceptors for botulinum neurotoxin A in the central and peripheral nervous systems

The main site of action for botulinum neurotoxin is cholinergic motor nerve terminals where specific acceptors concentrate the toxin on the cell surface, thereby facilitating its internalization and inactivation of a component essential for transmitter release. In this study, the interaction in vitro of [125I]botulinum neurotoxin type A with central and peripheral nerve terminals of different types was investigated using Ultrofilm and electron-microscope autoradiography. It was found that: (i) The neurotoxin binds to synapse-rich areas of rat brain, particularly in the hippocampus and cerebellum; identity of the neuron types labelled is unclear although cholinergic nerves seem to be labelled, perhaps not exclusively, in many areas. (ii) Toxin uptake at central nerve terminals appears to be minimal and its penetration into intact brain slices is restricted; this may account for the toxin's lower central toxicity. (iii) Selective labelling of cholinergic nerves but not purinergic, peptidergic or adrenergic nerve terminals in mouse ileum suggests that the toxin may be a specific marker for cholinergic nerves in the periphery. Based on these localization studies and published pharmacological observations, it is concluded that efficient toxin-induced blockade of neurotransmission depends on the presence of specific acceptors of high affinity for the toxin and of an effective neuronal uptake mechanism. Inhibition of the release of numerous transmitters from different kinds of nerve terminals lacking one of these features can be produced by high toxin concentrations when uptake occurs via low affinity acceptors or by non-specific means. Notably, this widespread action of the toxin indicates the occurrence of a common intracellular target in several, possibly all, nerve types.

Inhibition of messenger RNA transcriptional activity in ML-1 human myeloblastic leukemia cell nuclei by antiserum to a c-myb-specific peptide

Antiserum to a synthetic peptide that defines a hydrophilic region within the putative c-myb translation product was prepared in the rabbit. In lysates from exponentially growing ML-1, human myeloblastic leukemia cells, the antiserum ("anti-myb") reacted with five proteins of Mr 58,000, 75,000, 85,000, 90,000 and 105,000. Of these, only p75 and a trace of p85 were detected, by immunoblotting, in extracts derived from ML-1 cell nuclei. The proteins p58, p75 and p90 were present in readily detectable amounts only in the relatively immature myeloid cell lines ML-1 and HL-60, whereas in the more mature myeloid cell line THP-1 and in the lymphoid line BALL-1 only traces of these proteins were found. p85 and p105 were detected in lysates from all cell lines tested, including myeloid and lymphoid leukemia cells and mouse 3T3 cells. In lysates from ML-1 cells induced to differentiate to monocyte/macrophages or to granulocytes, the concentrations of p58 and p75 decreased in parallel with the cell population moving to maturity; in completely mature populations these two proteins were no longer detectable. In ML-1 cells arrested in G1 by serum depletion, the amount of p58 and p75 and to a smaller extent that of p90 was decreased, whereas the concentration of p85 and p105 remained unchanged. In nuclei from exponentially growing ML-1 cells, the antiserum or its derived immunoglobulin fraction ("anti-myb IgG") inhibited mRNA transcriptional activity by 30%. DNA synthesis was not affected. In contrast, in nuclei from differentiated ML-1 cells, the mRNA transcriptional activity was not significantly inhibited by anti-myb IgG. Similarly, in nuclei from ML-1 cells arrested largely in G1 by serum depletion for 2 days, mRNA transcriptional activity was inhibited by only 11%. Upon supplementation with serum, the mRNA transcriptional activity inhibitable by anti-myb IgG increased in parallel with the increasing rate of cell growth. The difference in total mRNA transcriptional activity observed in nuclei from cells of different growth rate was accounted for by the difference in transcriptional activity inhibitable by anti-myb IgG.(ABSTRACT TRUNCATED AT 400 WORDS)

Interaction of 125I-labeled botulinum neurotoxins with nerve terminals. I. Ultrastructural autoradiographic localization and quantitation of distinct membrane acceptors for types A and B on motor nerves

The labeling patterns produced by radioiodinated botulinum neurotoxin (125I-BoNT) types A and B at the vertebrate neuromuscular junction were investigated using electron microscopic autoradiography. The data obtained allow the following conclusions to be made. 125I-BoNT type A, applied in vivo or in vitro to mouse diaphragm or frog cutaneous pectoris muscle, interacts saturably with the motor nerve terminal only; silver grains occur on the plasma membrane, within the synaptic bouton, and in the axoplasm of the nerve trunk, suggesting internalization and retrograde intra-axonal transport of toxin or fragments thereof. 125I-BoNT type B, applied in vitro to the murine neuromuscular junction, interacts likewise with the motor nerve terminal except that a lower proportion of internalized radioactivity is seen. This result is reconcilable with the similar, but not identical, pharmacological action of these toxin types. The saturability of labeling in each case suggested the involvement of acceptors; on preventing the internalization step with metabolic inhibitors, their precise location became apparent. They were found on all unmyelinated areas of the nerve terminal membrane, including the preterminal axon and the synaptic bouton. Although 125I-BoNT type A interacts specifically with developing terminals of newborn rats, the unmyelinated plasma membrane of the nerve trunk is not labeled, indicating that the acceptors are unique components restricted to the nerve terminal area. BoNT types A and B have distinct acceptors on the terminal membrane. Having optimized the conditions for saturation of these binding sites and calibrated the autoradiographic procedure, we found the densities of the acceptors for types A and B to be approximately 150 and 630/micron 2 of membrane, respectively. It is proposed that these membrane acceptors target BoNT to the nerve terminal and mediate its delivery to an intracellular site, thus contributing to the toxin's selective inhibitory action on neurotransmitter release.

Interaction of 125I-labeled botulinum neurotoxins with nerve terminals. II. Autoradiographic evidence for its uptake into motor nerves by acceptor-mediated endocytosis

Using pharmacological (Simpson, L.L., 1980, J. Pharmacol. Exp. Ther. 212:16-21) and autoradiographic techniques (Black, J.D., and J.O. Dolly, 1986, J. Cell Biol., 103:521-534), it has been shown that botulinum neurotoxin (BoNT) is translocated across the motor nerve terminal membrane to reach a postulated intraterminal target. In the present study, the nature of this uptake process was investigated using electron microscopic autoradiography. It was found that internalization is acceptor-mediated and that binding to specific cell surface acceptors involves the heavier chain of the toxin. In addition, uptake was shown to be energy and temperature-dependent and to be accelerated by nerve stimulation, a treatment which also shortens the time course of the toxin-induced neuroparalysis. These results, together with the observation that silver grains were often associated with endocytic structures within the nerve terminal, suggested that acceptor-mediated endocytosis is responsible for toxin uptake. This proposal is supported further by the fact that lysosomotropic agents, which are known to interfere with the endocytic pathway, retard the onset of BoNT-induced neuroparalysis and also affect the distribution of silver grains at nerve terminals treated with 125I-BoNT. Possible recycling of BoNT acceptors (an important aspect of acceptor-mediated endocytosis of toxins) at motor nerve terminals was indicated by comparing the extent of labeling in the presence and absence of metabolic inhibitors. On the basis of these collective results, it is concluded that BoNT is internalized by acceptor-mediated endocytosis and, hence, the data support the proposal that this toxin inhibits release of acetylcholine by interaction with an intracellular target.

The intrinsic and extrinsic arterial supply to the proximal phalanx of the hallux

The hallux is subject to numerous surgical procedures and very little is known about its blood supply. Arteriographic studies were performed in six cadaver specimens to identify the major arterial supply to the hallux. Discrepancies with now known anatomical models were discovered. In this study, the major arterial supply to the hallux appeared to originate from the lateral digital artery. In addition, two transverse digital arteries were noted to emit the nutrient arteries of the phalanges. Examination of other arteriographic studies sustained our results.

Localization of sites for 125I-labelled botulinum neurotoxin at murine neuromuscular junction and its binding to rat brain synaptosomes

Botulinum neurotoxin, purified to homogeneity from Clostridium botulinum (Type A), was found to be highly neurotoxic (greater than 8 X 10(7) mouse LD50/mg protein). Labelling of this pure neurotoxin with 125I-iodine to high specific radioactivity was achieved without appreciable loss of biological activity. This was used to demonstrate saturable binding sites for this toxin at the neuromuscular junction, following in vivo administration into mice. A demonstrable inhibitory effect of the neurotoxin on release of acetylcholine from rat cerebrocortical synaptosomes indicates that it affects synapses in the central nervous system. Kinetic studies on the binding of 125I-labelled neurotoxin to brain synaptosomes yielded an association rate constant of 2.3 x 10(5)M-1s-1; dissociation plots were biphasic and the predominant species showed a rate constant of 1.2 X 10(-4)s-1. The saturable binding component is heat-sensitive and inactivated by trypsin. Preliminary studies showed that botulinum neurotoxin associates with plasma membrane fractions of synaptosomes and that binding does not result in any gross structural changes, at least in the majority of the toxin molecules.

Reversible cartilage staining technique for defining articular weight-bearing surfaces

A reversible cartilage staining technique, applicable to anatomical specimens, has been developed to define the weight-bearing patterns of the ankle joint. The method represents a rapid and accurate procedure for the determination of cartilage contact patterns in multiple positions of function. This technique should prove a useful tool in the detection of weight-bearing areas of other synovial joints.

Acupuncture and placebo: Effects on delaying the terminating response to a painful stimulus

An experiment was performed to determine whether needles inserted into appropriate acupuncture points could delay onset of a pain-terminating response more than needles inserted as placebos into inappropriate points could. A heat source contained in a modified Hardy-Wolff-Goodell dolorimeter was used as a stimulus to produce pain on the posterolateral aspects of the left forearms of volunteer subjects. Subjects pressed a switch as soon as pain was experienced, and the latency between stimulus onset and response was measured to the nearest hundredth of a second. Response latencies were recorded before and after needling, which included electrical stimulation. Needles placed in specific acupuncture points called Ho-Ku and Wai-Kaun delayed onset of the pain-terminating response slightly more than needles inserted as placebos. Even with needles in appropriate acupuncture points, analgesia was slight and subjects still experienced pain.

Electrical stimulation and its effects on growth and ion accumulation in tomato plants

The effect of small increments of direct current on the growth and ion uptake in Scotia tomato plants was determined. The natural endogenous current in the plant was first assessed and the current applied to reinforce or oppose the natural with three treatment durations per day. Significant increases in linear growth (5 to 30%) were obtained and also significant increases in uptake by the plants of K, Ca, and P when currents were between 15 and 3 μA per plant with the plant negative to the ground. A reduction in growth occurred when the plants were treated with 15 μA positive to the ground or with any currents of magnitude greater than 30 μA per plant. The increased ion accumulation seems not to be merely a passive movement under the applied potential, and it is thought that small currents may stimulate active ion pumps or alter the internal distribution of growth-regulating compounds in a somewhat erratic manner.