Selective A1-adenosine receptor antagonists identified using yeast Saccharomyces cerevisiae functional assays.

Evaluation of a biased "library" of pyrrolo[2,3-d]pyrimidines using yeast-based functional assays expressing human A1- and A2a-adenosine receptors, led to the A1 selective antagonist 4b. A direct correlation between yeast functional activity and binding data was established. Practical compounds with polar residues at C-4 of the pyrrolopyrimidine system required H-bond donor functionality for high potency.

Impacts of structural photomodification on the toxicity of environmental contaminants: anthracene photooxidation products.

The toxicity of polycyclic aromatic hydrocarbons (PHAs) is known to be enhanced by light via photosensitization reactions (production of active oxygen) and photomodification of the chemicals (e.g., oxidation) to more toxic compounds. Anthracene (ANT) toxicity in particular has been found to increase dramatically following photomodification. The objective of this study was to identify the photooxidation products of ANT and assess the toxicity of selected photoproducts. High performance liquid chromatography (HPLC) analysis of anthracene photooxidation revealed a complex array of oxidation products; prevalent among these were anthraquinone (ATQ) and hydroxy-anthraquinones (hATQs). Eleven of these compounds were tested for toxicity using growth inhibition of the duckweed Lemna gibba L. G-3. All but one of the compounds tested were found to be toxic, and when UV radiation was present in the light source toxicity was generally enhanced. The chemicals were also irradiated under SSR prior to toxicity testing. In about half the cases, the ATQ compounds were rapidly photooxidized and the resultant photoproducts were more toxic than the parent compounds. Interestingly, 2-hydroxyanthraquinone, which was not subject to photooxidation, was the most toxic of the compounds tested. As a light stable compound it presents the risk of a persistent environmental hazard.

Considering a smaller world. Review.

PIP: This article reviews the book written by Bill McKibben entitled "Maybe One". In view of the fact that overpopulation is of paramount concern in developing countries, McKibben argues that curbing population growth in the US--where 270 million people consume 3 times the amount of resources consumed by India's 1 billion people--may be a global imperative. He further promotes a sort of environmental triage, declaring that those efficient technologies and simplified lifestyles "are not going to happen easily and speedily". Both reducing the size of our ecological footprint and increasing the efficiency with which resources are used will be essential to moving back from the brink of environmental catastrophe. The backbone and the bite of McKibben's writing are his insistence on animating the pages with the intimate struggles of his own life. The most intriguing sections of "Maybe One" are his efforts to connect the abstract and worrisome statistics of population growth to his own decision to have one child. He expressed, "all I want is to open a debate, to remove ¿population¿ from the category of abstraction and make it the very real consideration of how many children you and I may decide to bear."^ieng

Expression of receptors for epidermal growth factor and insulin-like growth factor I by ZR-75-1 human breast cancer cell variants is inversely related: the effect of steroid hormones on insulin-like growth factor I receptor expression.

We have investigated the expression of insulin-like growth factor I receptors (IGFR) by the ZR-75-1 human breast cancer cell line and tamoxifen-resistant (ZR-75-9a1) and oestrogen-independent (ZR-PR-LT) variants. ZR-75-1 cells expressed 6633+/-953 receptors per cell,(K(d) 0.24+/-0.06 nM). IGFR expression was reduced in ZR-75-9a1 cells (1180+/-614 receptors per cell, K(d) 0.13+/-0.05) and increased in the ZR-PR-LT cell line (18 430+/-3210 receptors per cell, K(d) 0.24+/-17). A comparison of these data with previously published findings for epidermal growth factor receptor (EGFR) expression by these cell lines revealed that IGFR and EGFR expression are inversely related in the variant lines whereas ZR-75-1 cells express similar numbers of both receptors. Since the changes in IGFR expression observed are associated with changes in steroid hormone receptor status, we also investigated the effects of oestradiol, the synthetic progestin ORG 2058 and dexamethasone on IGFR expression. Oestradiol increased IGFR expression only in the ZR-75-1 cell line. Low concentrations of ORG 2058 increased IGFR levels in the two cell lines positive for progesterone receptor (ZR-75-1 and ZR-PR-LT). High concentrations of ORG 2058 increased IGFR expression in all cell lines, as did dexamethasone. These data suggest that EGFR and IGFR expression may be linked in breast cancer, and that EGFR/IGFR ratios in breast cancer may be a more sensitive prognostic indicator than EGFR expression alone. Regardless of basal IGFR expression by the cell studied, ORG 2058 increased IGFR expression, possibly via both the progesterone and glucocorticoid receptors.

Changes in insulin-like growth factor-I receptor expression and binding protein secretion associated with tamoxifen resistance and estrogen independence in human breast cancer cells in vitro.

Conditioned medium from a series of human breast cancer cell lines representing the phenotypes of estrogen dependence ZR-75-1, MCF-7), tamoxifen resistance (Z(+)-75-9a1, LY2) and estrogen independence (ZR-PR-Lt) contained four detectable insulin-like growth factor binding proteins (IGFBPs) of MW 24, 34, 44 and 70 kDa. in the tamoxifen resistant lines secretion of the 24 kDA IGFBP was depressed in comparison to the parent lines whilst secretion of the 44 kDa IGFBP was unaffected. Secretion of this species by ZR-PR-LT cells was reduced. Following incubation in medium containing 1% serum both tamoxifen resistant cell lines secreted higher levels of the 44 kDa IGFBP than the respective parent lines. These changes in IGFBP secretion associated with the development of tamoxifen resistance and estrogen independence were accompanied by changes in the expression of receptors for IGF-1.

Immunoreactive endothelin distribution in ocular tissues.

PURPOSE: To study the distribution of the endothelins in the eye using ocular tissues of human, rat, and porcine origin. METHODS: Extracts of ocular tissues were examined for immunoreactivity to endothelin 1 and 3 and pro-endothelin 1 using radioimmunoassay. Characterization of immunoreactivity was verified using high-performance liquid chromatography. RESULTS: Immunoreactivity to endothelin 1 and endothelin 3 was found in all ocular tissues except the cornea, which contained no immunoreactivity to endothelin 3. Highest levels were found in the choroid, although species-related differences were present. Immunoreactivity to endothelin 3 was generally twofold to threefold higher than immunoreactivity to endothelin 1. The majority of endothelin-like-immunoreactivity in the retina was blood vessel-associated. High-pressure liquid chromatography (HPLC) confirmed that immunoreactive endothelin 1 and endothelin 3 in the tissue extracts eluted in identical positions to their respective standard synthetic peptides. CONCLUSIONS: The endothelins are abundantly distributed in the eye. Endothelin 1 is present in its mature, 21 amino acid form, and only minimal amounts of the precursor pro-endothelin is found in ocular tissues. The wide distribution patterns point to complex roles for these peptides in blood vessel physiology and in such other functions as regulation of aqueous outflow, and in neurotransmission or modulation.

Treatment of portwine stains using the pulsed dye laser.

Five years of clinical experience of the treatment of portwine stains using the flashlamp-pumped dye laser is presented. The dye laser, when turned to a wavelength of 577 nanometres with a short pulsewidth of the order of 340 microseconds, may be used to target selectively the dilated vasculature constituting the lesion. Patients with ages ranging from 5-45 years were treated under general anaesthetic using a computer controlled scanning system developed by the authors. Several repeat treatments were found to be necessary. Results are presented ranging from total eradication of the lesion to marginal lightening only. No scarring of the treated sites was evident.

Changes in epidermal growth factor receptor expression and response to ligand associated with acquired tamoxifen resistance or oestrogen independence in the ZR-75-1 human breast cancer cell line.

We have examined the expression of receptors for epidermal growth factor (EGFR) by the ZR-75-1 human breast cancer cell line and tamoxifen resistant (ZR-75-9al 8 microM) and oestrogen independent/tamoxifen sensitive (ZR-PR-LT) variants. The parent line expressed a single class of high affinity binding sites (4,340 +/- 460 receptors/cell; Kd 0.23 +/- 0.04 nM). ZR-75-9al 8 microM cells, routinely maintained in medium containing 8 microM tamoxifen, were negative for oestrogen receptor (ER) and progesterone receptor (PGR) and expressed a markedly increased number of EGFR (14,723 +/- 2116 receptors/cell). Receptor affinity was unchanged. Time dependent reversal of the tamoxifen resistant phenotype was accompanied by a return to ER and PGR positivity and a fall in EGFR numbers to parent cell levels. In contrast ZR-PR-LT cells had a greatly reduced EGFR content (803 +/- 161 receptors/cell) accompanying elevated PGR numbers. Pre-treatment of these cells with suramin or mild acid stripping failed to expose receptors which may have been occupied by endogenously produced ligand. Increased proliferation of ZR-75-1 cells treated with EGFR (0.01-10 ng ml-1) was only observed in serum-free medium lacking insulin and oestradiol. Under these conditions untreated cells failed to proliferate. Both variant lines continued to proliferate in serum free medium in the absence or presence of insulin and oestradiol but failed to respond to exogenous EGF.

Modulation by oestrogen and progestins/antiprogestins of alpha interferon receptor expression in human breast cancer cells.

Human breast cancer ZR-75-1 cells expressed 1516 (105) (mean [S.D.]) interferon (IFN) receptors (IFNR) per cell with Kd of 0.61 (0.15) nmol/l. Oestrogen independent ZR-PR-LT and tamoxifen resistant ZR-75-9a1 8 mumol/l cells expressed similar numbers of IFNR. ZR-75-9a1 cells, which had been maintained in the absence of tamoxifen or known oestrogenic activity for 46 weeks, expressed a significantly higher number of IFNR (3170 [315]). Exposure of ZR-75-1 cells to 10(-9) mol/l 17 beta-oestradiol (E2) led to a consistent reduction in IFNR numbers whilst 10(-6) mol/l tamoxifen slightly increased IFNR expression. Since IFN increases oestrogen receptors in this cell line, IFN and E2 appear to have opposite effects on expression of each others' receptor. 10(-9) mol/l medroxy progesterone acetate and mifepristone significantly increased IFNR numbers whilst ORG 2058 decreased IFNR expression and ZK 98.299 had no effect. Progestin/antiprogestin induced IFNR increase in this cell line correlated with down-regulation of progesterone receptor (PR). Thus an IFN/ER/PR axis may exist in ZR-75-1 cells and variants.

Preventing colorectal cancer.

Knowledgeable patients should not die of colorectal cancer. Increasing the intake of dietary fiber, decreasing fat consumption, and increasing the use of modern technology to detect adenomatous polyps and early cancer can greatly decrease the mortality associated with colorectal cancer.

Preoperative versus postoperative adjuvant radiotherapy for surgically curable carcinoma of the rectum and distal sigmoid colon.

From January 1979 to October 1986, 86 patients with surgically resectable adenocarcinoma of the rectum or rectosigmoid were treated with adjuvant radiotherapy consisting of preoperative 2,400 cGy (22 patients), preoperative 4,000 cGy (14 patients), "sandwich" technique (27 patients), and postoperative irradiation (23 patients). Average follow-up was 42.9 months. The local recurrence rate was 4.5%, 9.1%, 7.4%, and 34.8%, respectively. The distant metastasis rate was 18.2%, 18.2%, 7.4%, and 30.4%, respectively. Preoperative radiotherapy with adequate surgical resection appears more effective in reducing the incidence of local recurrence.

Correlation of cardiovascular and neuroendocrine tests of autonomic function in diabetes.

Six normal subjects and 16 insulin-dependent diabetics with varying degrees of autonomic damage each had blood sampled for norepinephrine and pancreatic polypeptide for fifteen minutes after a mixed meal and intravenous (IV) edrophonium (Tensilon). The normal subjects showed a brisk but short-lived rise in norepinephrine after edrophonium (average maximum increase 70% between 2 and 6 minutes), as did most diabetics. However, diabetics with cardiovascular reflex evidence of sympathetic damage showed no rise in norepinephrine. Pancreatic polypeptide concentrations increased up to 400% above baseline after a mixed meal in both the normal and the diabetic group with normal cardiovascular reflexes. There was no significant rise in pancreatic polypeptide either in the diabetics with parasympathetic damage alone or in those with additional sympathetic damage. These results provide further evidence for the diffuse nature of the damage in diabetic autonomic neuropathy.

Effects of eight weeks' continuous treatment with oral ranitidine and cimetidine on gastric acid secretion, pepsin secretion, and fasting serum gastrin.

Gastric acid secretion, pepsin secretion, and fasting serum gastrin levels were measured in 23 patients with duodenal ulcer disease, divided into three groups which received either cimetidine 800 mg daily, cimetidine 1600 mg daily, or ranitidine hydrochloride 300 mg daily for eight weeks. Pentagastrin tests were carried out at intervals both before and after treatment. Each dose of cimetidine reduced acid secretion to 42% of control one week after starting therapy. Ranitidine reduced acid secretion to 33% of the pretreatment value. Acid secretion remained suppressed to these levels throughout treatment with each drug. Acid secretion returned to pretreatment levels in all patients one week after treatment and remained normal until the end of the study. Both drugs reduced pepsin, which fell to 64% and 61% (p less than 0.01) after 800 mg and 1600 mg cimetidine respectively and to 65% (p less than 0.005) with ranitidine after one week's treatment. Pepsin secretion remained at this reduced level in both cimetidine groups till the end of treatment. Pepsin levels fell to 50% at two weeks of therapy with ranitidine but stabilised at this level till the end of therapy. Cimetidine withdrawal was followed by a return towards pretreatment levels of pepsin secretion; but secretion remained significantly depressed (p less than 0.05) to the end of the study period. In the ranitidine-treated patients pepsin output returned to normal after drug withdrawal. Fasting gastrin levels rose during treatment with both drugs but failed to reach significant levels. After withdrawal of treatment fasting serum gastrin levels returned to normal in all three groups of patients.