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Biomedical subjects

D J Buckley

Publications and source records attributed to D J Buckley.

At least 55 records · Page 3Linked to original sources
PubMed1995

Rapid activation of mitogen-activated protein kinase and p21ras by prolactin and interleukin 2 in rat Nb2 node lymphoma cells.

Several serine/threonine and tyrosine kinase signal transduction pathways have been recently linked to prolactin (PRL) action in lymphoid cells. Utilizing the lactogen-dependent, rat pre-T lymphoma cell line, Nb2-11, and the autonomous subline, Nb2-SFJCD1, studies were conducted to determine whether PRL- or interleukin-2 (IL-2)-stimulated Nb2 cell proliferation is coupled to the activation of p21ras and mitogen-activated protein (MAP) kinase. Stimulation of Nb2-11 cells, growth-arrested in the early G1 phase of the cell cycle, with PRL or IL-2 rapidly (5-10 min) provoked GTP binding to Ras, enhanced tyrosyl phosphorylation of MAP kinase, significantly increased its enzymatic activity, and caused its nuclear translocation. The phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), which directly activates protein kinase C, similarly activated Ras and MAP kinase but failed to cause its nuclear translocation. Tyrosine kinase antagonism with genistein inhibited PRL-stimulated Ras and MAP kinase activation. In other experiments, Ras and MAP kinase were each found to be constitutively active in the Nb2-SFJCD1 line. The addition of PRL to these cultures enhanced the activity of these signaling proteins. Finally, the effects of PRL, IL-2, TPA, and phosphatase inhibition on Nb2-11 cell population density and [3H]thymidine uptake were compared. The addition of PRL, IL-2, and TPA significantly stimulated[3H] thymidine incorporation, while only the polypeptide growth factors augmented cell density. Phosphatase inhibition had no effect on either parameter. These results indicate that Nb2 cell proliferation is associated with the early activation of Ras and MAP kinase. Moreover, tyrosyl phosphorylation upstream of Ras activation appears to be required for its subsequent stimulation of mediators, which activate MAP kinase. Protein kinase C activation may be coupled to MAP kinase activation but is not sufficient for Nb2 cell proliferation.

Animals↗
PubMed1994

Prolactin-induced phosphorylation and nuclear translocation of MAP kinase in Nb2 lymphoma cells.

The coupling of prolactin (PRL) receptor ligation to activation of mitogen-activated protein (MAP) kinase was sought in rat Nb2 lymphoma cells, a pre-T lymphocyte line dependent upon lactogens for proliferation. Addition of PRL (20 ng/ml) to Nb2 cells, growth arrested in the early G1 phase of cell cycle, stimulated rapid tyrosyl phosphorylation of MAP kinase (min). Phosphorylated MAP kinase subsequently translocated to the nucleus, with kinetics essentially identical to those demonstrated for nuclear accumulation of PRL. The rapidity of MAP kinase activation suggests an intermediary role for this enzyme in PRL receptor signalling. Moreover, nuclear translocation of MAP kinase provides an interactive mechanism by which PRL, together with its nuclear receptor, may regulate transcription requisite for mitogenesis.

Animals↗
PubMed1994

Determination of polychlorinated biphenyl levels in the serum of residents and in the homogenates of seafood from the New Bedford, Massachusetts, area: a comparison of exposure sources through pattern recognition techniques.

We measured the residues of polychlorinated biphenyls (PCBs) in the serum of 23 residents of the New Bedford, Massachusetts, area and from two homogenates each of bluefish and lobsters from the same area. We used congener-specific and total Aroclor quantitative approaches, both of which involved gas chromatography with electron capture detection. Using gas chromatography mass spectrometry (electron ionization mode), we confirmed the presence of PCBs in the combined serum samples and in the aliquots of bluefish and lobsters. In measuring the PCB levels in serum, we found good agreement between the two electron capture detector approaches (r > or = 0.97) when the serum of specific congeners was compared to total Aroclor. We used univariate and multivariate quality control approaches to monitor these analyses. Analytical results for bluefish showed a better agreement between the two techniques than did those for lobsters; however, the small number of samples precluded any statistical comparison. We also measured levels of chlorinated pesticides in the serum samples of two groups of New Bedford residents, those with low PCB levels (< 15 ng/ml) and those with high PCB levels (> or = 15 ng/ml). We found that residents with high PCB levels also tended to have higher levels of hexachlorobenzene (HCB) and 1,1-dichloro-2,2-di-(p-chlorophenyl) ethylene (p,p'-DDE). The higher concentration of all three analytes appears to be influenced by employment in the capacitor industry, by seafood consumption, or both. Using Jaccard measures of similarity and principal component analysis we compared the gas chromatographic patterns of PCBs found in the serum of New Bedford area residents with high serum PCBs with the patterns found in homogenates of lobsters (inclusive of all edible portions except the roe), in homogenates of bluefish fillets taken from local waters, and in serum from goats fed selected technical Aroclors (e.g. Aroclors 1016, 1242, 1254, or 1260). The patterns found in human serum samples were similar to the patterns found in lobster homogenates. Both of these patterns closely resembled patterns found in the serum samples of the goat fed aroclor 1254, as demonstrated by both pattern recognition techniques. In addition, the chromatographic patterns of human serum and of lobsters and bluefish homogenates all indicated the presence of PCBs more characteristic of Aroclors 1016 or 1242.

Analysis of Variance↗
PubMed1994

Suramin, a protein kinase C inhibitor, impairs hepatic regeneration.

Previously we have shown that partial hepatectomy (PH) or exposure of the liver to the mitogen prolactin induces activation of hepatic protein kinase C (PKC). Here, we used suramin, an antitrypanosomal and chemotherapeutic drug which inhibits that enzyme, as a probe of PKC signal transduction in the regenerative response after PH in the rat. Suramin was administered i.p. in nonhepatotoxic doses of 20 to 160 mg/kg 14 days prior to PH. Three measures of hepatic DNA synthesis or cell division, thymidine kinase activity, [3H]thymidine incorporation, and mitotic index were inhibited in a dose-dependent fashion. Baseline PKC activity, in both the cytosolic and particulate fractions, was unchanged by suramin. After PH, PKC activation, signalled by an increase in activity in the particulate fraction, was observed in control rats at 30 and 60 min. However, rats which had previously received suramin demonstrated dose-dependent inhibition of PKC activation. Suramin is known to also disrupt the binding of certain growth factors to their receptors. But if inhibition of PKC activation were conferred by interference with growth factor-receptor binding by suramin, then the generation of diacylglycerol, the second messenger for PKC activation, should likewise be impaired. However, we observed that the diacylglycerol mass generated at 15, 30, and 45 min after PH was not altered by suramin pretreatment. We conclude that the diminution in DNA synthesis after PH by suramin is likely the consequence of direct inhibition of PKC, suggesting that PKC activation is an important, perhaps obligatory, signal transduction event in liver regeneration.

Animals↗
PubMed1994

Neural and endocrine mechanisms of cocaine-induced 70-kDa heat shock protein expression in aorta and adrenal gland.

Cocaine has properties of a physiologic stressor that are reflected by its ability to activate both the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system. We have previously reported that activation of the hypothalamic-pituitary-adrenal axis and sympathetic nervous system by restraint and pharmacologic agents induces expression of a set of highly conserved cellular stress response proteins (heat shock proteins, HSP) in the adrenal gland and aorta. In the adrenal gland, HSP expression appears to be mediated by stress-induced increases in adrenocorticotropic hormone whereas expression in the aorta involves noradrenergic neurotransmission. In this report we capitalize on the ability of cocaine to stimulate physiologic stress responses to define further mechanisms regulating HSP70 expression in these tissues. We report the novel observation that cocaine administration induces both adrenal and vascular HSP70 mRNA expression. Elevated HSP70 mRNA was preceded by activation of factors capable of binding to the heat shock transcriptional control element and was followed by an elevation in HSP70 protein. Cocaine significantly increased plasma adrenocorticotrophic hormone whereas hypophysectomy eliminated cocaine-induced expression in the adrenal gland suggesting that in this tissue, the effect of cocaine on HSP70 expression is also mediated via adrenocorticotrophic hormone. In the aorta, depletion of catecholamines by reserpine pretreatment paradoxically augmented cocaine-induced HSP70 expression. Based on these results, it appears that HSP70 expression in the aorta occurs through direct actions of cocaine on vascular cells that are ultimately transduced to activation of the HSP70 gene rather than indirectly through alterations in catecholamine reuptake and release.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Glands↗
PubMed1993

Purse-string suture for stapled oesophagogastric anastomosis: hand-sewn versus automatic.

An automatic purse-string device was compared with the traditional hand-sewn method in stapled oesophageal anastomosis. Fifteen greyhound dogs underwent distal oesophagectomy with stapled gastro-oesophageal anastomosis; a purse-string suture was used to draw the distal oesophagus around the stapling device. The animals were randomized into group 1 (n = 8), in which the automatic device was used, and group 2 (n = 7), in which the oesophageal purse string was hand-sewn. The automatic device failed to incorporate the oesophageal mucosa and submucosa reliably into the anastomotic staple line. There were five defective anastomoses in group 1 and none in group 2 (P = 0.037). Anastomotic bursting pressures were significantly reduced in group 1 compared with group 2 (median (range) 47 (22-110) versus 82 (68-88) mmHg, P = 0.032). Within group 1, a significant difference in bursting pressure existed between complete anastomoses and those in which the mucosa was not fully incorporated (median (range) 75 (60-110) versus 39 (22-50) mmHg, P = 0.037). Median (range) breaking strengths where anastomoses were incomplete were lower than where all layers were incorporated (1420 (1250-2220) versus 1990 (1590-2475) g/cm, P = 0.009). This study questions the safety of the automatic purse-string device for oesophageal anastomosis when used in accordance with present recommendations. Further evaluation and possibly modification of either the instrument design or the methods recommended by the manufacturer for its use are warranted.

Anastomosis, Surgical↗
PubMed1993

Inhibition by genistein of prolactin-induced Nb2 lymphoma cell mitogenesis.

Tyrosine kinase activation in mediating the mitogenic action of prolactin (PRL) has been evaluated. Use was made of genistein, a tyrosine kinase antagonist, and cultured rat Nb2 lymphoma cells, i.e. the lactogen-dependent Nb2-11 line and a lactogen-independent subline, Nb2-SFJCD1. Genistein was found to be a potent growth-inhibitor for both lines, inhibiting 3H-thymidine incorporation in Nb2-11 and Nb2-SFJCD1 cells with IC50s of 4.2 and 6.7 micrograms/ml, respectively. Genistein also inhibited expression and translation of the heat shock protein 70 gene and pp40 protein substrate phosphorylation which, in Nb2-11 cells, followed PRL addition within minutes. Genistein inhibition of DNA synthesis in G1-arrested Nb2-11 cells was most pronounced if the agent was added within 1 h of PRL treatment. The results indicate that, while both Nb2 cell lines have a general growth requirement for tyrosyl phosphorylation, the early, PRL-induced tyrosine kinase activation is a component of the PRL mitogenic signal transduction pathway.

Animals↗
PubMed1993

Dopaminergic regulation of heat shock protein-70 expression in adrenal gland and aorta.

The induction of heat shock proteins (HSPs) by cellular stress and activation of the hypothalamic-pituitary-adrenal axis and sympathetic nervous system by physiological stress are biological responses that aid in the maintenance of cellular and organismal homeostasis, respectively. Based on previous studies, we have hypothesized that HSPs play a functional role in neural and endocrine stress response mechanisms in mammalian organisms. To determine the endocrine and/or neural components regulating stress-induced HSP70 expression in vivo, we have employed the long-acting synthetic propylergoline dopamine agonist CQP 201-403 (CQP). We report the novel observation that CQP mimics the effect of restraint stress to induce HSP70 expression in both adrenal gland and aorta of the rat. The presence of CQP-induced HSP70 mRNA and protein was preceded by the activation of a protein factor capable of binding to the heat shock transcriptional control element. CQP-induced HSP70 expression in the adrenal gland was restricted to the cortex, as previously observed in restraint-stressed animals. However, the distribution of expression among the three cortical layers was distinct. Hypophysectomy virtually eliminated the effects of CQP on the adrenal gland and markedly reduced HSP70 induction in the aorta. Collectively, these results provide evidence that dopaminergic systems contribute to the physiological regulation of HSP70 expression in adrenal gland and aorta directly through actions on receptors in responsive tissues and/or indirectly through the release of pituitary hormones.

Adrenal Cortex↗
PubMed1993

Nuclear co-localization of prolactin and the prolactin receptor in rat Nb2 node lymphoma cells.

Previous studies have indicated that prolactin (PRL) interacts with specific, high affinity, immunoreactive binding sites within isolated rat hepatocyte nuclei. Moreover, endogenous PRL appears to be bound to this site. However, it remained important to demonstrate nuclear PRL receptors and hormonal translocation in an intact cell system. Therefore, we sought nuclear translocation of PRL and its receptor in the nucleus of PRL-dependent Nb2 node lymphoma cells. Utilizing immunofluorescence (IF) microscopy, growth-arrested cells were found to constitutively express the PRL receptor in the nucleus and in the membrane/cytosol compartments. Addition of PRL stimulated rapid hormone internalization followed by translocation to the nucleus within 6-12 hrs. The translocation of PRL was found to be reversible and dependent upon ATP. These results indicate that an early event coupled to the mitogenic action of PRL in Nb2 cells is hormone transport to the nucleus during the G1 and S phases of cell cycle. Once in the nucleus, PRL bound to its receptor may directly influence gene transcription.

Adenosine Triphosphate↗
PubMed1992

Polytetrafluoroethylene in above-knee arterial bypass surgery for critical ischemia.

Seventy-one consecutive above-knee polytetrafluoroethylene (PTFE) femoropopliteal arterial bypasses performed between 1981 and 1989 for critical ischemia were followed prospectively to determine graft patency and limb salvage. Cumulative graft patency and limb salvage rates were calculated by life table analysis. Graft patency was 80%, 68%, 55%, 39%, and 39%, and limb salvage 97%, 87%, 84%, 77%, and 77% at 1, 2, 3, 4, and 5 years, respectively. Twenty-nine grafts have occluded with re-emergence of critical ischemia in 14, treated by 5 amputations and 9 reconstructions using autogenous saphenous vein (ASV) in 6 and PTFE in 3. These favorable results are not as good in terms of primary patency as those reported with ASV, but good limb salvage, good early patency, ease of use, and preservation of the saphenous vein for use later have encouraged us toward primary use of PTFE in selected patients. This experience strongly questions the wisdom of an "all autogenous" policy for reconstruction at this level.

Amputation, Surgical↗
PubMed1991

Problems associated with interferences in the analysis of serum for polychlorinated biphenyls.

During a recent survey to determine serum concentrations of polychlorinated biphenyls (PCBs) among people living around New Bedford, MA, U.S.A., an unidentified contaminant precluded the quantification of some early eluting Webb and McCall peaks. Loss of data is estimated to have reduced reported serum levels by 12%. Efforts to identify the contaminant by gas chromatography with an electron-capture detector, a Hall electrolytic condutivity detector, and mass spectrometer were not successful. Researchers ascertained, however, that the contaminant is not a PCB, it does not contain halogens, but it may contain phthalates. Vacutainer tubes and closures for serum storage bottles are suspected sources of contamination.

Chromatography, Gas↗
PubMed1991

Mediastinoscopy as a predictor of resectability in patients with bronchogenic carcinoma.

Eighty consecutive mediastinoscopies, performed for assessment of patients with bronchogenic carcinoma, were reviewed with regard to accuracy and complications. Thirty patients had mediastinal lymph node metastases: 26 were considered inoperable and thus saved non-therapeutic thoracotomy, 4 were considered operable of whom 3 had a curative resection, and one was inoperable at thoracotomy. Of 50 patients with negative mediastinal nodes 43 had thoracotomy; 42 were resectable and one was unresectable. Seven did not have thoracotomy because of other contraindications. In total of 47 patients undergoing thoracotomy on the basis of mediastinoscopy, 45 were resectable, giving mediastinoscopy a positive predictive value for resectability of 95.7%. There was no mortality and two superficial wound infections occurred giving a morbidity of 2.5%. Mediastinoscopy is a safe, reliable and accurate predictor or resectability in patients with bronchogenic carcinoma and continues to have a major role in the management of these patients.

Aged↗
PubMed1991

Prolactin-stimulated ornithine decarboxylase induction in rat hepatocytes: coupling to diacylglycerol generation and protein kinase C.

The trophic effects of prolactin (PRL) in rat liver have been linked to activation of protein kinase C (PKC). Since alterations in PKC activity imply its activation by 1,2-diacylglycerol (DAG), we tested whether PRL treatment stimulated DAG generation coupled to induction of a growth response in primary hepatocytes. Addition of PRL to hepatocyte cultures significantly increased [3H]-glycerol incorporation into DAG within 5 minutes which was followed by a loss of cytosolic PKC activity by 10 minutes. Prolactin also significantly enhanced radiolabel incorporation into triacylglycerol and phospholipids within 10 minutes and induced ODC activity at 6 hours. Therefore, prolactin-stimulated alterations in PKC activity are preceded by enhanced DAG generation. Moreover, these events appear to be coupled to PRL-stimulated entry of hepatocytes into cell cycle.

Animals↗
PubMed1990

Protein kinase C inhibitors block insulin and PMA-stimulated hexose transport in isolated rat adipocytes and BC3H-1 myocytes.

Effects of protein kinase C (PKC) inhibitors and "down-regulation" on insulin and PMA-stimulated 2-deoxyglucose transport were determined in isolated rat adipocytes or BC3H-1 myocytes. In both model systems, H-7, sangivamycin, and staurosporine, inhibitors of the catalytic domain of PKC, each effectively blocked insulin and PMA-stimulated hexose uptake at similar concentrations. In the myocytes, staurosporine completely blocked the insulin effect retained post-chronic phorbol myristate acetate (PMA)-induced "down-regulation." These findings indicate (1) that chronic pretreatment with PMA may not lead to a complete loss of PKC activity in the myocyte, and (2) that PKC is involved in insulin-stimulated hexose transport in both isolated rat adipocytes and BC3H-1 myocytes.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1990

Oral complications in type 1B glycogen storage disease.

A case of type 1b glycogen storage disease (GSD) in which neutropenia and neutrophil dysfunction were prominent features is described. Oral complications included rapidly progressive periodontal disease and recurrent mucosal ulceration.

Adult↗
PubMed1990

Calcium antagonists and the "stunned" myocardium.

Hearts which are made ischemic for relatively short periods of time, and then re-perfused, exhibit a temporary decline in tension-generating activity but are not irreversibly injured". Experiments were undertaken to find out whether such "stunned" hearts develop a perfusion defect, and whether chemically heterogeneous Ca(2+)-antagonists provide protection, when used prophylatically. "Stunning" was produced by repetitive 10 minute episodes of ischemia, followed by 15 minutes of reperfusion. The experimental model was the Langendorff-perfused rat heart, and the perfusion buffer was Krebs-Henseleit solution at 37 degrees C. To detect perfusion defects, fuchsin dye was added to the buffer. No evidence of a perfusion defect was obtained. Nevertheless, 10(-8)M nifedipine. 10(-8)M verapamil, 10(-8)M felodipine, and 10(-7)M diltiazem all conferred protection, as gauged by recovery of function after three successive 10 minute episodes of ischemia.

Animals↗