Chronic Exposure to Nitric Oxide Induces P53 Mutations and Malignant-like Features in Human Breast Epithelial Cells

The small endogenous signaling molecule nitric oxide (NO) has been linked with chronic inflammation and cancer. The effects of NO are both concentration and temporally dependent; under some conditions, NO protects against damage caused by reactive oxygen species and activates P53 signaling. During chronic inflammation, NO causes DNA damage and inhibits repair proteins. To extend our understanding of the roles of NO during carcinogenesis, we investigated the possible effects of chronic NO exposure on MCF10A breast epithelial cells, as defined by changes in cellular morphology, chromosome/genomic stability, RNA, and protein expression, and altered cell phenotypes. Human MCF10A cells were maintained in varying doses of the NO donor DETANO for three weeks. Distinct patterns of genomic modifications in TP53 and KRAS target genes were detected in NO-treated cells when compared to background mutations. In addition, quantitative real-time PCR demonstrated an increase in the expression of cancer stem cell (CSC) marker CD44 after prolonged exposure to 300 μM DETANO. While similar changes in cell morphology were found in cells exposed to 300-500 μM DETANO, cells cultured in 100 μM DETANO exhibited enhanced motility. In addition, 100 μM NO-treated cells proliferated in serum-free media and selected clonal populations and pooled cells formed colonies in soft agar that were clustered and disorganized. These findings show that chronic exposure to NO generates altered breast epithelial cell phenotypes with malignant characteristics.

Standard and flexible tip bougie for tracheal intubation using a non-channelled hyperangulated videolaryngoscope: a randomised comparison. Anaesthesia 2022;77:1368-1375. [PMID: 36066179 DOI: 10.1111/anae.15854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Bougie impingement during tracheal intubation can increases the likelihood of prolonged intubation time, failed intubation and airway trauma. A flexible tip bougie may overcome this problem, which can occur when using a non-channelled, hyperangulated videolaryngoscope with a standard bougie. This randomised controlled study compared standard and flexible tip bougies using a non-channelled videolaryngoscope (C-MAC® D-blade) in 160 patients. The primary outcome measure was the modified intubation difficulty scale score. Secondary outcome measures were: laryngoscopy time; total tracheal intubation time; first attempt success rate; and postoperative sore throat verbal rating score. The median (IQR [range]) modified intubation difficulty scale scores for standard bougie and flexible tip bougie were 1 (0-2[0-5]) and 0 (0-1[0-3]), respectively (p = 0.001). There was no significant differences in laryngoscopy time, total tracheal intubation time, first attempt success rate and postoperative sore throat between the two groups. Both the flexible tip and standard bougies can be used with a high first attempt success rate for tracheal intubation using a C-MAC D-blade videolaryngoscope. The flexible tip bougie demonstrated a significantly better modified intubation difficulty scale score and lower incidence of bougie impingement.

Brain connectome modularity in weight-restored anorexia nervosa and body dysmorphic disorder

BACKGROUND

Anorexia nervosa (AN) and body dysmorphic disorder (BDD) frequently co-occur, and have several overlapping phenomenological features. Little is known about their shared neurobiology. The aim of the study was to compare modular organization of brain structural connectivity.

METHOD

We acquired diffusion-weighted magnetic resonance imaging data on unmedicated individuals with BDD (n = 29), weight-restored AN (n = 24) and healthy controls (HC) (n = 31). We constructed connectivity matrices using whole-brain white matter tractography, and compared modular structures across groups.

RESULTS

AN showed abnormal modularity involving frontal, basal ganglia and posterior cingulate nodes. There was a trend in BDD for similar abnormalities, but no significant differences compared with AN. In AN, poor insight correlated with longer path length in right caudal anterior cingulate and right posterior cingulate.

CONCLUSIONS

Abnormal network organization patterns in AN, partially shared with BDD, may have implications for understanding integration between reward and habit/ritual formation, as well as conflict monitoring/error detection.

Nitroxide derivatives of non-steroidal anti-inflammatory drugs exert anti-inflammatory and superoxide dismutase scavenging properties in A459 cells

BACKGROUND AND PURPOSE

Inflammation and reactive oxygen species are associated with the promotion of various cancers. The use of non-steroidal anti-inflammatory drugs (NSAIDs) in cancer prevention treatments has been promising in numerous cancers. We report the evaluation of NSAIDs chemically modified by the addition of a redox-active nitroxide group. TEMPO-aspirin (TEMPO-ASA) and TEMPO-indomethacin (TEMPO-IND) were synthesized and evaluated in the lung cancer cell line A549.

EXPERIMENTAL APPROACHES

We evaluated physico-chemical properties of TEMPO-ASA and TEMPO-IND by electron paramagnetic resonance and cyclic voltammetry. Superoxide dismutase-like properties was assayed by measuring cytochrome c reduction and anti-inflammatory effects were assayed by measuring production of prostaglandin E(2) (PGE(2) ) and leukotriene B(4) (LTB(4) ). MTT proliferation assay and clonogenic assay were evaluated in the A549 lung carcinoma cell line. Maximum tolerated doses (MTD) and acute ulcerogenic index were also evaluated in in vivo.

KEY RESULTS

MTD were: TEMPO (140 mg·kg(-1) ), ASA (100 mg·kg(-1) ), indomethacin (5 mg·kg(-1) ), TEMPO-ASA (100 mg·kg(-1) ) and TEMPO-IND (40 mg·kg(-1) ). While TEMPO-ASA was as well tolerated as ASA, TEMPO-IND showed an eightfold improvement over indomethacin. TEMPO-IND showed markedly less gastric toxicity than the parent NSAID. Both TEMPO-ASA and TEMPO-IND inhibited production of PGE(2) and LTB(4) in A549 cells with maximum effects at 100 µg·mL(-1) or 10 µg·mL(-1) respectively.

CONCLUSIONS AND IMPLICATIONS

The nitroxide-NSAIDs retained superoxide scavenging capacity of the parent nitroxide and anti-inflammatory effects, inhibiting cyclooxygenase and 5-lipoxygenase enzymes. These redox-modified NSAIDs might be potential drug candidates, as they exhibit the pharmacological properties of the parent NSAID with antioxidant activity decreasing NSAID-associated toxicity.

MEASURING INTER-HEMISPHERIC INTEGRATION IN BIPOLAR AFFECTIVE DISORDER USING BRAIN NETWORK ANALYSES AND HARDI

Bipolar disorder is characterized by extreme mood swings, including both manic and depressive episodes commonly accompanied by psychosis. Many imaging studies have investigated white matter changes in bipolar illness, and the results have suggested abnormal intra- and inter-hemispheric white matter structures, particularly in the fronto-limbic and callosal systems. However, some inconsistency remains in the literature, and no study to-date has utilized brain network analysis using graph theory. Here, we acquired 64-direction diffusion weighted imaging (DWI) on 25 euthymic bipolar I subjects and 25 gender/age matched healthy subjects. White matter integrity measures were computed and compared in 50 white matter ROIs. The results indicated impaired integrity in the corpus callosum. Guided by this, we constructed whole brain structural connectivity networks using graph theory. We devised brain network metrics (inter-hemispheric path length and efficiency) to further probe inter-hemispheric integration, and demonstrated relatively preserved intra-hemispheric but significantly impaired inter-hemispheric integration in our bipolar subjects.

NIH deltanoids meeting on Vitamin D and cancer. Conclusion and strategic options

A meeting on "Cancer Chemoprevention and Cancer Treatment; role of vitamin D, 1alpha,25-(OH)(2)D(3) and deltanoids" was held on the NIH Congres, Bethesda in November 2004. The following conclusions were presented at the end of this symposium. Vitamin D deficiency and insufficiency are worldwide problems and are associated with several health problems including higher cancer prevalence. There is convincing evidence that the active vitamin D hormone, 1alpha,25(OH)(2)D(3), can decrease cell proliferation, modify cell apoptosis and control malignant cell growth. Therefore academia, public funding agencies and industry should urgently design appropriate studies to better define the causal relationship between vitamin D nutrition and cancer, define the optimal vitamin D nutrition based on accurate 25(OH)D measurement and inform the public and medical profession accordingly. Selective vitamin D receptor modulators are a potentially interesting new class of chemopreventive and chemotherapeutic agents as demonstrated by several first generation analogs have provided a convincing proof of concept. In the mean time, the public should be informed about the risks of vitamin D deficiency and insufficiency and appropriate steps should be taken to improve the vitamin D nutritional status of large parts of the world population.

The effects of adrenomedullin overexpression in breast tumor cells

BACKGROUND

Adrenomedullin is a secreted peptide hormone with multiple activities. Several reports have indicated that adrenomedullin may be involved in tumor survival, but this has not been directly shown. Here we evaluate the in vitro and in vivo effects of adrenomedullin overexpression in human breast cancer cells.

METHODS

The human breast cancer cell lines T47D and MCF7, both of which express low basal levels of adrenomedullin, were stably transfected with an expression construct that contained the coding region of the human adrenomedullin gene or with empty expression vector. Properties of the transfected cells were assessed by proliferation and apoptosis assays, in vitro and in vivo angiogenesis assays, cell migration experiments, and xenograft implants. The effect of synthetic adrenomedullin on human ovarian (ECV) cancer cell motility was also tested. Western blot analysis was used to compare expression levels of several genes whose products are associated with cell growth and regulation of apoptosis.

RESULTS

T47D and MCF7 cells transfected with the adrenomedullin construct both expressed high levels of adrenomedullin mRNA and protein. Compared with cells transfected with empty vector, cells that overexpressed adrenomedullin displayed a more pleiotropic morphology, an increased angiogenic potential both in vitro and in vivo, and less apoptosis after serum deprivation. T47D and MCF7 cells did not display measurable motility, but ECV ovarian cancer cells treated with synthetic adrenomedullin were more motile than saline-treated ECV cells. Adrenomedullin-overexpressing T47D cells had higher levels of proteins involved in oncogenic signal transduction pathways (such as Ras, Raf, PKC, and MAPKp49) and lower levels of pro-apoptotic proteins (such as Bax, Bid, and caspase 8) than T47D cells transfected with empty vector. In a preliminary in vivo experiment, three of 10 nude mice injected with adrenomedullin-overexpressing T47D cells developed xenograft tumors, whereas none of the 10 nude mice injected with cells carrying the empty plasmid developed tumors.

CONCLUSIONS

These results further support the role of adrenomedullin as a survival factor for tumors. Development of physiologically efficient inhibitors of adrenomedullin may prove useful in the clinical management of cancer.

Five-lipoxygenase inhibitors can mediate apoptosis in human breast cancer cell lines through complex eicosanoid interactions

Many arachidonic acid metabolites function in growth signaling for epithelial cells, and we previously reported the expression of the major arachidonic acid enzymes in human breast cancer cell lines. To evaluate the role of the 5-lipoxygenase (5-LO) pathway on breast cancer growth regulation, we exposed cells to insulinlike growth factor-1 or transferrin, which increased the levels of the 5-LO metabolite, 5(S)-hydrooxyeicosa-6E,8C,11Z,14Z-tetraenoic acid (5-HETE), by radioimmunoassay and high-performance liquid chromatography. Addition of 5-HETE to breast cancer cells resulted in growth stimulation, whereas selective biochemical inhibitors of 5-LO reduced the levels of 5-HETE and related metabolites. Application of 5-LO or 5-LO activating protein-directed inhibitors, but not a cyclooxygenase inhibitor, reduced growth, increased apoptosis, down-regulated bcl-2, up-regulated bax, and increased G1 arrest. Exposure of breast cancer cells to a 5-LO inhibitor up-regulated peroxisome proliferator-activated receptor (PPAR)a and PPARg expression, and these same cells were growth inhibited when exposed to relevant PPAR agonists. These results suggest that disruption of the 5-LO signaling pathway mediates growth arrest and apoptosis in breast cancer cells. Additional experiments suggest that this involves the interplay of several factors, including the loss of growth stimulation by 5-LO products, the induction of PPARg, and the potential activation of PPARg by interactions with shunted endoperoxides.

Imaging tumors in humans with Tc-99m-VIP

Vasoactive intestinal peptide (VIP) was modified at the C terminus with a spacer and four amino acids to serve as a chelating moiety. The modified peptide, TP 3654, was labeled with Tc-99m and evaluated in normal volunteers, as well as in patients with a history of cancer. Renal clearance (67%) was the primary route of excretion, with approximately 20% of the radioactivity clearing through the hepatobiliary system. No adverse reaction was noted in any of the subjects and all, except one small, of the known lesions as seen by CT, MRI, Tc-99m-MIBI, or mammography were correctly identified within a few minutes of an i.v. injection of approximately 10 mCi of Tc-99m-TP 3654 (specific activity 11.3 x 10(3) Ci/m mol). The scans were in concordance in nine patients. In the remaining two, one with a visible mass in the neck from high grade spindle cell sarcoma and the other with a palpable mass in a breast from ductal epithelial hyperplasia, were localized only with Tc-99m-TP 3654, but not with Tc-99m-MIBI. Both malignancies are known to express VIP receptors. The VIP analog promises to be a nontoxic and reliable agent for imaging cancers in humans that express VIP receptors.

Expression of proadrenomedullin derived peptides in the mammalian pituitary: co-localization of follicle stimulating hormone and proadrenomedullin N-20 terminal peptide-like peptide in the same secretory granules of the gonadotropes

Expression of proadrenomedullin-derived peptides in the rat, cow and human pituitary was studied by a variety of techniques. Immunocytochemical detection showed a widespread expression of adrenomedullin peptide in the adenohypophysis and the neural lobe, with low expression in the intermediate pituitary. Proadrenomedullin N-20 terminal peptide (PAMP)-immunoreactivity was also present in the anterior pituitary but showed a more marked heterogeneous distribution, with cells going from very strong to negative immunostaining. Lower levels of PAMP were found in the neural lobe. Interestingly, the distribution of adrenomedullin and PAMP immunoreactivity in the anterior pituitary did not completely overlap. In the present study, we concentrated our efforts to determine which cell type of the adenohypophysis expresses PAMP. Paraffin and semithin serial sections immunostained for PAMP and the classical pituitary hormones revealed that a subpopulation of the gonadotropes expresses high levels of PAMP-immunoreactive material. Ultrastructural analysis clearly showed PAMP-immunoreactivity in the follicle stimulating hormone (FSH)-containing large secretory granules of the gonadotropes, suggesting simultaneous secretion of PAMP and FSH by this cell type. Three mouse adenohypophysis-derived cell lines (AtT20, GH3, and alphaT3-1 derived from corticotropes, lacto/somatotropes and gonadotropes, respectively) were also analysed and showed expression of both proadrenomedullin-derived peptides and their mRNA. Functional studies in these three cell lines showed that neither adrenomedullin nor PAMP was able to stimulate cAMP production in our experimental conditions. Taken together, our results support that proadrenomedullin derived peptides are expressed in the pituitary in cell-specific and not overlapping patterns, that could be explained by differences in postranslational processing. Our data showing costorage of PAMP and FSH in the same secretory granules open a way by which PAMP could be involved in the control of reproductive physiology in a coordinated manner with FSH.

Targeting sigma receptor-binding benzamides as in vivo diagnostic and therapeutic agents for human prostate tumors

Sigma receptors are known to be expressed in a variety of human tumor cells, including breast, neural, and melanoma tumors. A very high density (1.0-1.5 million receptors/cell) of sigma receptors was also reported in a human androgen-dependent prostate tumor cell line (LNCaP). In this study, we show that a very high density of sigma receptors is also expressed in an androgen-independent human prostate tumor cell line (DU-145). Pharmacological binding studies using the sigma-1-selective ligand [3H](+)-pentazocine showed a high-affinity binding (Kd = 5.80 nM, Bmax = 1800 fmol/mg protein). Similarly, binding studies with [3H]1,3-di-o-tolylguanidine in the presence of dextrallorphan also showed a high-affinity binding (Kd = 15.71 nM, Bmax = 1930 fmol/mg protein). Radioiodinated benzamide N-[2-(1'-piperidinyl)ethyl]-3-[125I]iodo-4-methoxybenzamide ([125I]PIMBA) was also shown to bind DU-145 cells in a dose-dependent manner. Three different radioiodinated benzamides, [125I]PIMBA, 4-[125I]iodo-N-[2-(1'-piperidinyl)ethyl]benzamide, and 2-[125I]-N-(N-benzylpiperidin-4-yl)-2-iodobenzamide, were screened for their potential to image human prostate tumors in nude mice bearing human prostate cells (DU-145) xenografts. All three compounds showed a fast clearance from the blood pool and a high uptake and retention in the tumor. Therapeutic potential of nonradioactive PIMBA was studied using in vitro colonogenic assays. A dose-dependent inhibition of cell colony formation was found in two different human prostate cells. These results demonstrate the potential use of sigma receptor binding ligands in non-invasive diagnostic imaging of prostate cancer and its treatment.

Growth control of lung cancer by interruption of 5-lipoxygenase-mediated growth factor signaling

Signal transduction pathways shared by different autocrine growth factors may provide an efficient approach to accomplish clinically significant control of lung cancer growth. In this study, we demonstrate that two autocrine growth factors activate 5-lipoxygenase action of the arachidonic acid metabolic pathway in lung cancer cell lines. Both growth factors increased the production of 5(S)-hydrooxyeicosa-6E,8Z,11Z,14Z-tetraeno ic acid (5-HETE), a major early 5-lipoxygenase metabolic product. Exogenously added 5-HETE stimulated lung cancer cell growth in vitro. Inhibition of 5-lipoxygenase metabolism by selective antagonists resulted in significant growth reduction for a number of lung cancer cell lines. Primary clinical specimens and lung cancer cell lines express the message for the 5-lipoxygenase enzymes responsible for the generation of active metabolites. In vivo evaluation demonstrated that interruption of 5-lipoxygenase signaling resulted in enhanced levels of programmed cell death. These findings demonstrate that 5-lipoxygenase activation is involved with growth factor-mediated growth stimulation for lung cancer cell lines. Pharmacological intervention with lipoxygenase inhibitors may be an important new clinical strategy to regulate growth factor-dependent stages of lung carcinogenesis.

The in vitro dissociation kinetics of (R,R)-[125I]4IQNB is reflected in the in vivo washout of the radioligand from rat brain

We have determined the kinetics of dissociation of (R)-3-Quinuclidinyl (R)-4-[125I]Iodobenzilate ((R,R)-[125I]4IQNB) from muscarinic acetylcholine receptor preparations from the cortex, hippocampus, caudate/putamen, thalamus, pons and colliculate bodies. The dissociation curves are well described by a biexponential function and are consistent with subtype selectivity favoring slow dissociation from the M1, M3, and M4 receptors with a 20-fold faster dissociation rate for the M2 receptor. Following intravenous injection, (R,R)-[125I]4IQNB binds to receptor in the rat brain in concentrations which reflect the receptor concentration present in a structure. We determined the extent of radioligand present at two times, 2 and 24 hrs, as an indication of the relative proportions of m-AChR which exhibits rapid vs. slow dissociation of (R,R)-[125I]4IQNB. A good correlation between in vitro and in vivo results suggests that the relative populations of receptor subtypes can be imaged using in vivo pharmacokinetics of (R,R)-[125I]4IQNB.

Metabolism of murine and human embryos: search for a growth indicator in vitro culture medium

Ham's F-10 medium was analyzed biochemically before and after growth of murine and human embryos. Ham's F-10 medium (280 mosm/kg, pH 7.4) alone, by means of reverse-phase high-performance liquid chromatography, demonstrated one major hydrophilic peak, which eluted at 4 to 8 minutes in a 10% to 48% acetonitrile gradient. This peak showed a single peptide of 50 kilodaltons in one-dimensional polyacrylamide gel electrophoresis and size exclusion high-performance liquid chromatography. After the growth of two-cell murine embryos to eight-cell embryos or blastocysts, the major hydrophilic peak was greatly reduced or absent in the culture medium, and in turn a major hydrophobic peak appeared that eluted at 29 minutes. The major hydrophobic peak could not be focused in one-dimensional polyacrylamide gel electrophoresis, but a high content of polar and nonpolar amino acids was revealed in N-terminal sequencing and mass spectrometric analysis. This shift in the peaks was not detected when embryos were cultured in the presence of 0.02% sodium azide. In vitro culture of human zygotes from the pronuclear stage to two to eight cells caused a similar disappearance of the major hydrophilic peak concomitant with the appearance of one to three major hydrophobic peaks in the culture medium. We conclude that the change in profile of culture medium from hydrophilic to hydrophobic peaks on high-performance liquid chromatography is indicative of the metabolic pattern of murine and human embryos. These data also indicate that murine and human embryos do not secrete any major peptide during their development in vitro.

Bombesin: a potent mitogen for small cell lung cancer

While advances in the diagnosis and staging of SCLC have been made over the past decade, overall therapeutic results remain essentially unchanged. However, during this time period there have been major advances in understanding the biology of this tumor cell type. The recognition of considerable heterogeneity among SCLC cells may be of prognostic importance, while the demonstration of specific growth factors, including bombesin, for this tumor type may open up new means for endocrine therapy of lung carcinoma in vivo. Over the next 5-10 yr, studies of clinical trials using specific antibodies or analogs of bombesin-like growth factors in patients with SCLC will define more clearly the role of BLI and GRP in patients with this disease.

Factors influencing murine embryo bioassay: effects of proteins, aging of medium, and surgical glove coatings

The 2-cell murine embryo bioassay as quality control for human in vitro fertilization (IVF) was used to evaluate the effects of protein supplements, medium aging, and surgical glove coatings. Ham's F-10 medium (GIBCO, Grand Island, NY) without protein supplementation supported growth of the 2-cell embryos to blastocysts. Addition of bovine serum albumin (BSA), fetal cord serum (FCS), or maternal serum (MS) did not enhance or reduce the blastulation rates (medium alone, 89.4%; BSA, 86.4%; FCS, 90%; MS, 74.7%). Unsupplemented Ham's F-10 medium was found to contain three major peaks of approximately 50,000 daltons and several minor peaks, analyzed on high-performance liquid chromatography (HPLC) and sodium sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), suggesting the presence of protein(s) in the medium itself. The storing of medium up to 425 days at 4 degrees C affected neither the HPLC profile nor its ability to support embryo growth (blastulation rates: fresh, 84%; stored 150 to 425 days, 77.7%). The coating of surgical gloves affected embryo growth. Both talc-coated (TC) and "talc-free," starch-coated (SC) surgical gloves were found to be progressively embryotoxic when they touched the medium for increasing lengths of time, compared with uncoated latex (UL) gloves and untouched control medium. Quality control of medium preparation and handling in murine embryo bioassay is reemphasized, with requirements for protein supplementation, use of fresh medium, and possible contamination with even talc-free, SC surgical gloves reevaluated.

An atypical endocrine tumor of the lung responsive to radiation therapy and 5-fluorouracil-streptozotocin

A case is reported of a patient who presented with a peripheral left upper-lobe lung mass, a thyroid nodule, and multiple enlarged cervical and supraclavicular lymph nodes. Fine-needle aspiration cytology of the lung lesion, the thyroid nodule, and several of the lymph nodes was interpreted as small cell cancer of the lung (SCCL). The patient was treated with Cytoxan (cyclophosphamide), Adriamycin (doxorubicin), and vincristine (CAV), alternating with VP-16 + cisplatin. When progressive disease was documented after three cycles of chemotherapy, an involved cervical lymph node was biopsied. By light microscopy (LM) the tumor appeared to be a poorly differentiated adenocarcinoma, but by transmission electron microscopy (TEM) it was found to have both neuroendocrine and glandular features. Biochemical analysis of the biopsy specimen revealed immunoreactive bombesin, and on immunoperoxidase staining many tumor cells contained neuron-specific enolase. The tumor was therefore classified as an atypical endocrine tumor of the lung (AETL), a recently described morphologic variant for which no therapy has yet been established. The patient was treated with radiation therapy (RT) followed by chemotherapy including 5-fluorouracil (5-FU) (500 mg/m2 IV, d 1-5) and streptozotocin (STZ) (500 mg/m2 IV, d 1-5) every 5-6 weeks, with objective evidence of tumor regression following each modality. This report illustrates the importance of ultrastructural study in the characterization of lung cancer, and indicates the need for the further evaluation of RT and 5FU + STZ in the treatment of neuroendocrine tumors of the lung.

[Changes in the content of opiate-like substances in auricular electroacupuncture anesthesia of rats]

It was shown that auricular electro-acupuncture in rats, sufficient to induce analgesia, resulted in a significant increase of endorphins in cerebro-spinal fluid with a concomitant decrease in the basomedial hypothalamus and medial thalamus of beta-endorphin-like immunoreactivity as well as endorphin-like radioreceptor activity. In addition, the radioreceptor assay also revealed a decrease of endorphin-like radioreceptor activity in the periaqueductul gray matter. plasma levels of endorphins were not altered. Cerebro-spinal fluid contained only endogenous opiate ligand material with enkephalin-like molecular weight.

Computerized axial tomography in diagnosis of retroperitoneal abscess

Experience with computerized axial tomography (CT scan) in the diagnosis of retroperitoneal abscess in 3 patients is presented. We believe it is a useful diagnostic tool in this disease.

Uses of fluorescent cholinergic analogues to study binding sites for cholinergic ligands in Torpedo californica acetylcholine receptor

A series of synthetic 1,n-bis(3-aminopyridinio)-alkane fluorescent probes have been used to determine the ligand binding properties of the acetylcholine receptor purified from Torpedo californica electroplax. At equilibrium, the probes bound to a single class of sites. The binding affinity of the fluorescent decamethonium analogues increased progressively as the number of methylene groups (n) increased from 4 to 12 and decreased in the range of 16--18 such groups. The receptor bound 1,12-bis(3-aminopyridinio)dodecane and 1,14-bis(3-aminopyridinio)tetradecane with the highest affinity while related monofunctional probes such as 1-(3-amino-pyridinio)propane were bound with a substantially lower affinity. The data indicate that the receptor interacts strongly with both ends of a bifunctional probe such as 1,14-bis(3-aminopyridinio)tetradecane. Also, competition between bifunctional fluorescent probe binding and the binding of conventional cholinergic ligands, was investigated and led to the conclusion that the probes, which are antagonists, form ternary complexes in the presence of acetylcholine.

Interaction of bombesin and litorin with specific membrane receptors on pancreatic acinar cells

We have prepared (125)I-labeled [Tyr(4)]bombesin and have examined the kinetics, stoichiometry, and chemical specificity with which the labeled peptide binds to dispersed acini from guinea pig pancreas. Binding of (125)I-labeled [Tyr(4)]-bombesin was saturable, temperature-dependent, and reversible and reflected interaction of the labeled peptide with a single class of binding sites on the plasma membrane of pancreatic acinar cells. Each acinar cell possessed approximately 5000 binding sites, and binding of the tracer to these sites could be inhibited by [Tyr(4)]bombesin [concentration for half-maximal effect (Kd), 2 nM], bombesin (Kd, 4 nM), or litorin (Kd, 40 nM) but not by eledoisin, physalemin, somatostatin, carbachol, atropine, secretin, vasocative intestinal peptide, neurotensin, or bovine pancreatic polypeptide. At high concentrations (>0.1 muM), cholecystokinin and caerulein each caused a small (15-20%) reduction in binding of lableled [Tyr(4)]bombesin. With bombesin, litorin, and [Tyr(4)]bombesin, there was a close correlation between the relative potency for inhibition of binding of labeled [Tyr(4)]bombesin and that for stimulation of amylase secretion. For a given peptide, however, a 10-fold higher concentration was required for half-maximal inhibition of binding than for half-maximal stimulation of amylase secretion, calcium outflux, or cyclic GMP accumulation. These results indicate that dispersed acini from guinea pig pancreas possess a single class of receptors that interact with [Tyr(4)]bombesin, bombesin, and litorin and that occupation of 25% of these receptors will cause a maximal biological response.