Biomedical subjects

I Bird

Publications and source records attributed to I Bird.

13 recordsLinked to original sources

PubMed2001

Laparoscopic cholecystectomy does not demonstrably decrease survival of patients with serendipitously treated gallbladder cancer.

BACKGROUND: The purpose of this study was to evaluate the possibility that laparoscopic cholecystectomy has worsened the prognosis of patients with resected gallbladder cancer; particularly for patients whose cancer was accidentally resected. STUDY DESIGN: We conducted a retrospective review of Connecticut Tumor Registry data and data extracted from individual patient records at 15 of 30 hospitals in Connecticut reporting data to the Registry, at two separate time points, 1985-1988 (immediate prelaparoscopic era) and 1992-95 (laparoscopic cholecystectomy well established). There were 194 and 208 patients in each 3-year period, respectively. Additional information was extracted from hospital records in 82 and 91 patients, respectively. Twenty-five percent of patients in both data sets presented with "local" or Tis, T1, T2 disease. RESULTS: Three-year survival for localized disease was 29% in the prelaparoscopic period and 34% once laparoscopic cholecystectomy was established. But analysis of individual patient records indicated that 36% of patients from the laparoscopic period did not actually undergo a laparoscopic procedure. Fifty-nine patients had their gallbladder cancer discovered in the specimen postoperatively (serendipitously treated). A higher proportion of cancers were discovered postoperatively in the laparoscopic era (44% versus 24%). Three-year survival for these patients was 25%. If the data from the two eras are grouped according to whether or not the cancer-bearing gallbladder was manipulated laparoscopically, 24 of 59 patients (41%) turned out to be at risk for the possibility of increased laparoscopic dissemination of tumor. Survival of these patients (11-month median survival) was not statistically different from survival of patients whose serendipitously discovered gallbladder cancer was never manipulated laparoscopically (16-month median survival); p = 0.54 by log rank test. CONCLUSIONS: The widespread adoption of laparoscopic cholecystectomy did not worsen the survival of patients with gallbladder cancer, and patients with serendipitously treated gallbladder cancers did not have a worse survival after laparoscopic manipulation than after a standard open cholecystectomy. The laparoscopic aspects of operative manipulation of a gallbladder with cancer in it do not appear to be a proximate cause of the poor prognosis in this disease.

Aged↗

PubMed1997

Breast cancer cells have a high capacity to acidify extracellular milieu by a dual mechanism.

The extracellular pH in malignant tumors is known to be lower than in normal tissues and may therefore facilitate extracellular activation of secreted lysosomal cathepsins. We have tested the capability of human mammary cells (continuous cell lines and primary culture) to acidify their extracellular environment, using two techniques. By measuring pH changes through alterations of phenolsulfone phthaleine absorbance, we found that the more aggressive MDA-MB-231 human breast cancer cells were more active in acidifying a non-buffered balanced salt solution than the estrogen receptor positive MCF7 and ZR75 cell lines and than normal mammary epithelial cells in primary culture. Metastatic breast cancer cells from pleural effusions were up to 200-fold more active in acidifying their extracellular milieu than non-malignant mammary cells cultured in the same conditions, strongly suggesting that this difference also occurs in vivo. The use of inhibitors in the presence or absence of glucose showed that both lactate and an ATP-driven proton pump sharing some characteristics of the vacuolar H+ pump were involved. Bafilomycin A1, a specific inhibitor of the vacuolar (V-type) ATP-H+ pump inhibited part of the acidification by MCF7 cells, but not by MDA-MB-231 cells. We also used microelectrodes to measure extracellular pH, in close contact to the MCF7 breast cancer cells. The pH at the free surface of MCF7 cells was lower by 0.33 +/- 0.14 unit than that of the surrounding medium, while insertion of the microelectrode tip beneath the attached surface of the cells showed a greater lowering of pH from 0.3 to 1.7 pH unit as long as cell attachment on the substrate prevented H+ diffusion. We conclude that breast carcinoma cells have a higher capacity for acidifying their extracellular milieu than normal mammary cells, and that both a plasma membrane H(+)-ATPase, and lactic acid production are involved in this acidification. It is therefore possible that the aspartyl and cysteinyl pro-cathepsins secreted in excess by tumor cells may be activated extracellularly in vivo close to the basement membrane.

Acids↗

PubMed1996

The effect of insulin and insulin-like growth factors on the expression of steroidogenic enzymes in a human ovarian thecal-like tumor cell model.

OBJECTIVE: To determine the effects of insulin and insulin-like growth factors (IGF-I and IGF-II) on steroidogenesis and steroidogenic enzyme expression in a human ovarian thecal-like tumor cell culture model system. DESIGN: Human ovarian thecal-like tumor cells treated with forskolin and insulin IGF-I or IGF-II were evaluated for media accumulation of P and androstenedione (A) as well as 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) and cytochrome P450 17 alpha-hydroxylase (P450c17) enzyme activity. Northern analysis of cytochrome P450 side chain cleavage (P450scc), P450c17, and 3 beta HSD messenger RNA (mRNA) also was performed. RESULTS: Basal hormone secretion, enzyme activity, and mRNA levels were not affected by treatment with insulin or the IGFs. Forskolin treatment stimulated steroid production, enzyme activity, and mRNA content. Forskolin-stimulated P secretion was augmented 30% by treatment with insulin and IGFs, whereas 3 beta HSD activity was augmented twofold to threefold. Forskolin stimulated A and P450c17 activity were enhanced by treatment with insulin and the IGFs. In forskolin-treated cells. P450c17 and P450scc mRNA levels were not affected by insulin (100 nM) or IGF (10 nM) treatment; however, 3 beta HSD mRNA levels were augmented by treatment with insulin and IGFs. CONCLUSIONS: We observed that forskolin-stimulated human ovarian thecal-like tumor cell steroidogenesis, P450c17, and 3 beta HSD activity, as well as mRNA content for P450scc, 3 beta HSD, and P450c17. Insulin and the IGFs augmented forskolin-stimulated production of P and the expression of 3 beta HSD, with little effect on A production, P450scc, or P450c17 expression.

3-Hydroxysteroid Dehydrogenases↗

PubMed1993

Monitoring of exposure to styrene oxide by GC-MS analysis of phenylhydroxyethyl esters in hemoglobin.

Styrene oxide, which is the genotoxically active metabolite of styrene, reacts in vivo with carboxylic acid residues in hemoglobin forming phenylhydroxyethyl esters. Mild alkali hydrolysis cleaves these ester adducts, yielding styrene glycol, which in human blood labelled in vitro with 14C-styrene oxide accounted for 15% of the total radioactivity covalently bound to the protein. A quantitative assay procedure has been developed for measuring the base released styrene glycol in globin. The method utilizes solvent extraction followed by trimethylsilyl ether derivatization and separation and quantitation by capillary gas chromatography with selective ion recording mass spectrometry. Globin labelled in vitro with d8-styrene oxide was used as the internal standard. The method was used to establish a dose-response relationship in rats given single i.p. doses of styrene oxide (83.3-833 mumol/kg body wt). The method, which allows quantitation of the adducts down to levels of 15 pmol/g globin, has the potential to act as a dosimeter for industrial workers exposed to styrene or styrene oxide.

Animals↗

PubMed1990

Monitoring exposure to 4,4'-methylenedianiline by the gas chromatography-mass spectrometry determination of adducts to hemoglobin.

The determination of the covalently bound reaction products of 4,4'-methylenedianiline (MDA) to hemoglobin was investigated as a possible method for biological dosimetry in humans. The extent of binding to rat hemoglobin of MDA was determined by dosing animals with the 14C-ring-labeled compound. Two adducts were released from the hemoglobin on hydrolysis under mildly basic conditions which were identified as MDA and N-acetyl-MDA and accounted for between 36 and 45% of the total radioactivity bound to the protein. A quantitative assay procedure was subsequently developed for measuring both of the base released adducts in rat hemoglobin. The method utilized solvent extraction followed by derivatization with pentafluoropropionic anhydride and subsequent separation and quantitation by capillary gas chromatography with selective ion monitoring mass spectrometry using deuterium-labeled analogues of MDA and N-acetyl-MDA as internal standards. A dose-response relationship was established in orally dosed rats between production of each of the hemoglobin released adducts and dose of MDA (1-12 mg/kg). The possible use of such adduct determinations as dosimeters for industrial workers exposed to MDA is discussed.

Aniline Compounds↗

PubMed1988

Phenyl di-n-pentylphosphinate: a convenient reactivatible inhibitor for studies on neuropathy target esterase (NTE) and protection against organophosphate-induced delayed polyneuropathy.

Phenyl di-n-pentylphosphinate was synthesised by interaction of phenyl phosphorodichloridate and n-pentyl magnesium bromide. The product was purified by silica chromatography (yield 25%). Although much more stable at physiological pH than its 4-nitrophenyl analogue, this ester is a good inhibitor of neuropathy target esterase (NTE): kappa a = 1.7 X 10(5) M-1 min-1. It is a very weak anticholinesterase (kappa a congruent to 10 M-1 min-1). In vivo only 5-10 mg/kg is required to inhibit hen brain and spinal cord NTE. The inhibited NTE can be reactivated fully by incubation in vitro with iso-nitrosoacetophenone (INAP) (19 mM at 37 degrees C and pH 8.5 for 60 min): this property enables study to be made of the fate of inhibited NTE in vivo.

Animals↗

PubMed1987

The relationship between uncoupling of oxidative phosphorylation and neuronal necrosis within the CNS in rats dosed with trihalogenated imidazoles.

The trihalogenated imidazoles, trichloroimidazole (TCI), tribromoimidazole (TBI), and triiodoimidazole (TII), are in vitro uncouplers of oxidative phosphorylation with similar activities. Although TCI and TBI are also uncouplers in vivo, some doubt exists for TII, which is much less toxic and produces atypical signs of poisoning. Dibromo- and monobromoimidazole do not uncouple oxidative phosphorylation either in vitro or in vivo. Dosing of TCI and TBI to rats resulted within 24-48 hr in neuronal necrosis within the CNS involving the vestibular nucleus, red nucleus, and outer parietal neocortex and ataxia of the hindlimbs. However, no neuronal necrosis or ataxia was observed after dosing of TII to rats, even when given at doses four times greater than for either TCI or TBI, resulting in much higher brain concentrations. Although TBI was equitoxic to rats, mice, hamsters, and gerbils, CNS damage and ataxia were observed only in the rat, even though comparable brain concentrations of TBI were found in the gerbil. Measurement of the concentration of TBI in the dissected rat brain gave no indication of localized concentrations of compound in the areas associated with neuronal damage. Doses of TBI and the classical uncoupler 3,5-dinitro-o-cresol (DNOC), matched for whole body O2 consumption, caused comparable changes in rat brain blood flow although DNOC does not cause brain damage. Changes in blood flow were not restricted to those brain areas susceptible to damage. Thus, although we were unable to completely dissociate CNS damage from uncoupling of oxidative phosphorylation produced by TBI and TCI in the rat, it is unlikely that such damage is primarily related to the uncoupling ability of these compounds.

Animals↗

PubMed1986

Distinction between octachlorostyrene and hexachlorobenzene in their potentials to induce ethoxyphenoxazone deethylase and cause porphyria in rats and mice.

The potentials of octachlorostyrene (OCS) and hexachlorobenzene (HCB) to induce liver microsomal ethoxyphenoxazone deethylation (an indicator of induction of 3-methylcholanthrene and beta-naphthoflavone-like cytochrome P-450 monoxygenase activity) and cause porphyria in male C57BL/6 and C57BL/10 mice and female F344 rats were compared. Ethoxyphenoxazone deethylation was induced much more by HCB than by OCS in both of these strains of mice (although neither OCS nor HCB greatly induced deethylation in the DBA/2 strain). In rats ethoxyphenoxazone deethylase was induced 26-fold by HCB but only four-fold by OCS, whereas dealkylation of pentoxyphenoxazone (an indicator of phenobarbital-like induction) increased 43- and 36-fold, respectively. Both chemicals were poor inducers of dealkylation of pentoxyphenoxazone in mice. When fed HCB continuously but not when given OCS, C57BL/6 and C57BL/10 mice (both after pretreatment with iron) and F344 rats developed porphyria with a depression of hepatic uroporphyrinogen decarboxylase activity. The results illustrate that in these species OCS and HCB cannot be considered as equally efficient agents for inducing ethoxyphenoxazone deethylation or causing porphyria. If these effects are mediated through binding to the aromatic hydrocarbon responsiveness (Ah) receptor, HCB would appear to have a much greater affinity than OCS despite the face that neither chemical possesses a structure currently considered to be necessary for efficient binding.

Animals↗

PubMed1986

Monitoring exposure to acrylamide by the determination of S-(2-carboxyethyl)cysteine in hydrolyzed hemoglobin by gas chromatography-mass spectrometry.

Acrylamide is a potent cumulative neurotoxin in animals and man. In vivo exposure to this electrophile results in the formation of a covalently bound reaction product with cysteine residues in hemoglobin. This adduct yields on acid hydrolysis S-(2-carboxyethyl)cysteine which has been analyzed by capillary gas chromatography with mass spectrometry. Globin isolated from the blood of rats exposed to acrylamide was spiked with an internal standard (globin treated in vitro with d3-acrylamide) and was then hydrolyzed with 6 N HCl. The protein hydrolysate was fractionated on a Dowex 50W H+ ion exchange column and the amino acids in the partially purified extract were determined as N-heptafluorobutyryl methyl esters using an OV-1701 fused silica capillary column. Quantitation was made by chemical ionization (isobutane) selective ion monitoring in which the ions m/z 386 (M-OCH3)+ derived from derivatized S-(2-carboxyethyl)cysteine in the sample and the corresponding ion m/z 389 from the added deuterium-labeled internal standard were monitored. The dose-response relationship between production of hemoglobin adduct and dose of acrylamide (0.1 mg/kg-5 mg/kg) is curved, showing an increasing slope with increasing doses of acrylamide.

Acrylamide↗

PubMed1986

DNA and protein adducts as indicators of in vivo methylation by nitrosatable drugs.

Exposure to methylating carcinogens may be monitored by measuring both the formation of S-methylcysteine in haemoglobin and the urinary excretion of N-7-methylguanine (7-MeG), which is derived in part from methylated nucleic acids. Female rats were exposed to methylmethanesulphonate, methylnitrosourea and to three drugs, aminopyrine, cimetidine and pyrilamine, which are potential methylating agents if nitrosation occurs in vivo. Because S-methylcysteine in haemoglobin and urinary 7-MeG occur naturally, the experiments were carried out with stable isotope-labelled analogues which contained trideutero (d3)-methyl groups. Gas chromatography-mass spectrometry was used for the quantitative determination of d3-labelled adducts after their separation from the biological matrix and chemical derivatization. Transfer of the intact d3-methyl group to cysteine and guanine was detected after intragastric administration of d3-methyl-methanesulphonate (50 mg/kg), d3-N-methyl-N-nitrosourea (50 mg/kg), and d6-aminopyrine (AP) and sodium nitrite (both 100 mg/kg). AP alone gave no detectable d3-methyl adducts. Co-administration of nitrite and d6-pyrilamine or d3-cimetidine yielded no d3-7-MeG, although N-nitroso-d3-cimetidine alkylated DNA in vitro in a dose-dependent fashion. For AP and nitrite combinations urinary excretion of d3-7-MeG was linearly related to the dose of nitrite and was essentially complete within 5 days. For d3-methylmethane-sulphonate (50 mg/kg) the ratio of haemoglobin d3-S-methylcysteine to urinary d3-7-MeG was considerably (greater than 9-fold) higher than for either d3-N-methyl-N-nitrosourea or AP/nitrite (100 mg/kg) mixture. This is in accord with the SN2 nature of the weak carcinogen methylmethanesulphonate compared with the SN1 nature of the reactive methylating agent derived from either one of the N-methyl-N-nitroso compounds.

Animals↗

PubMed1983

Pyrrolic and N-oxide metabolites formed from pyrrolizidine alkaloids by hepatic microsomes in vitro: relevance to in vivo hepatotoxicity.

An analytical method of improved sensitivity has enabled measurements to be made of N-oxide as well as pyrrolic metabolites formed from a range of unsaturated pyrrolizidine alkaloids in hepatic microsome preparations. Using microsomes from livers of phenobarbitone-pretreated male Fischer rats, all 13 alkaloids tested were metabolised to both N-oxides and pyrroles. The most lipophilic alkaloids gave enhanced rates of metabolism. No consistent relationship existed between rates of N-oxide and of pyrrole formation. The two pathways appeared to be independent. The ratio of N-oxide to pyrrolic metabolites varied, depending on the type of ester: it was highest for 'open' diester alkaloids, lowest for 12 membered macrocyclic diesters and for monoesters. Steric hindrance by the acid moiety could account for these differences, by affecting the balance between microsomal oxidation of the amino alcohol moiety at the nitrogen and C8 positions respectively and could explain the high pyrrole yields given by some macrocyclic diesters. The levels of pyrrolic metabolites bound to liver tissues and responsible for hepatotoxicity in rats given pyrrolizidine alkaloids, did not necessarily reflect the rates of formation of such metabolites measured in vitro. In the animal additional factors could influence the formation and tissue binding of pyrrolic metabolites, including the detoxication of alkaloids by hydrolysis and the chemical reactivity and stability of the toxic metabolites. A comparison of heliotridine esters with retronecine esters showed that the 7-hydroxyl or -ester configuration had a relatively small influence on the balance between formation of pyrrolic metabolites and detoxication by N-oxidation. The results did not support any hypothesis that heliotridine esters should generally be more hepatotoxic than analogous retronecine esters. The structure of the acid moiety was likely to have at least as much influence on toxicity as the base configuration.

Animals↗

PubMed1983

Alkylation by dehydroretronecine, a cytotoxic metabolite of some pyrrolizidine alkaloids: an in vitro test.

A method is described for detecting alkylation of nucleophiles by dehydroretronecine (DHR) in vitro: whereas DHR is rapidly polymerised by acid, alkylation products of DHR were relatively stable and could be detected using Ehrlich reagent. Using this test, nitrogen-containing compounds found to react with DHR included pyridine, adenine and guanine derivatives; NAD and NADP, but not NADH; cytidine; barbituric and parabanic acids; and azide, but not cyanide. Out of 19 amino acids tested, only histidine, tryptophan and citrulline showed evidence of reaction. Among sulphur compounds, thiols, thiosulphate and sulphite reacted strongly; thioethers and thiocyanate did not. Carbohydrate and phenolic hydroxyls were unreactive but resorcinol and pyrogallol, having activated benzene nuclei, did react. Enols, especially ascorbic acid, reacted with DHR. Sites of reaction have not yet all been identified. Some DHR alkylations, e.g. of nicotinamide, could be reversible, and such products could in effect extend the life of DHR in vivo.

Alkylating Agents↗

PubMedDate not supplied

The effects of insulin on 3 beta-hydroxysteroid dehydrogenase expression in human luteinized granulosa cells.

OBJECTIVE: We determined the relative effects of insulin and FSH on progesterone accumulation as well as activity, protein content, and mRNA expression of 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) in human luteinized granulosa cells. METHODS: Luteinized granulosa cells obtained from women undergoing in vitro fertilization were plated and grown to near confluence and treated with FSH, insulin, or a combination of insulin and FSH. Progesterone production as well as enzyme activity, protein content, and mRNA expression for 3 beta HSD were evaluated. RESULTS: Progesterone production was not affected by insulin alone but increased threefold in the presence of FSH (50 ng/microL) alone. The presence of FSH plus insulin (100 nmol/L) caused a significant increase in progesterone accumulation greater than that of FSH alone. The already high basal levels of 3 beta HSD activity were unaffected by insulin alone but increased 1.7-fold in the presence of FSH. The combination of FSH (50 ng/mL) and insulin (100 nmol/L) increased activity 1.3-fold over FSH alone (P < .02). Insulin (greater than 100 nmol/L) alone increased 3 beta HSD protein content as measured by Western analysis 1.8-2-fold over basal levels, whereas FSH alone increased protein content 2.8-fold, and was further augmented by the addition of insulin in a dose-related fashion up to 3.5-fold over basal levels. Insulin increased 3 beta HSD mRNA twofold over basal levels; FSH alone increased mRNA expression of 3 beta HSD 3.2-fold. In the presence of insulin plus FSH, 3 beta HSD mRNA expression increased 7.6-fold over basal levels. For comparison, insulin also stimulated cytochrome P450 aromatase activity, P450 aromatase protein, and mRNA but to a greater degree than that seen for 3 beta HSD. CONCLUSION: Insulin is a regulator of both 3 beta HSD and aromatase expression in human granulosa cells. Elevated insulin levels could therefore affect steroid production in human granulosa cells and presumably alter the menstrual cycle and fertility.

3-Hydroxysteroid Dehydrogenases↗