Showing papers by "University of Tennessee Health Science Center published in 1989"

Nitric oxide-generating vasodilators and 8-bromo-cyclic guanosine monophosphate inhibit mitogenesis and proliferation of cultured rat vascular smooth muscle cells.

Abstract: Endothelium-derived relaxing factor has been recently identified as nitric oxide. The purpose of this study was to determine if vasodilator drugs that generate nitric oxide inhibit vascular smooth muscle mitogenesis and proliferation in culture. Three chemically dissimilar vasodilators, sodium nitroprusside, S-nitroso-N-acetylpenicillamine and isosorbide dinitrate, dose-dependently inhibited serum-induced thymidine incorporation by rat aortic smooth muscle cells. Moreover, 8-bromo-cGMP mimicked the antimitogenic effect of the nitric oxide-generating drugs. The antimitogenic effect of S-nitroso-N-acetylpenicillamine was inhibited by hemoglobin and potentiated by superoxide dismutase, supporting the view that nitric oxide was the ultimate effector. Sodium nitroprusside and S-nitroso-N-acetylpenicillamine significantly decreased the proliferation of vascular smooth muscle cells. Moreover, the inhibition of mitogenesis and proliferation was shown to be independent of cell damage, as documented by several criteria of cell viability. These results suggest that endogenous nitric oxide may function as a modulator of vascular smooth muscle cell mitogenesis and proliferation, by a cGMP-mediated mechanism.

Expression of Multidrug Resistance Gene in Human Cancers

Abstract: Chemotherapy has proven to be an effective treatment for the cure and palliation of some human cancers (Chabner, 1982). Some tumors, however, appear to be intrinsically resistant to chemotherapy. For cancers that can be treated with chemotherapy, based on the hypothesis that resistance to single agents occurs with high frequency, protocols involving multiple drugs with different intracellular targets have been designed. In many cases, such as acute lymphocytic leukemia and neuroblastoma (Simone et al., 1982), Hodgkin’s disease (De-Vita and Hellman, 1982), and germ cell cancers (Paulson et al., 1982), dramatic results have been achieved with such protocols. However, all too frequently relapse occurs after such therapy and the recurrent tumors are resistant to further chemotherapy. In effect, such tumors develop a multidrug resistance (MDR) phenotype that is very similar to the intrinsic resistance of some primary cancers.

Intracellular recording of identified neostriatal patch and matrix spiny cells in a slice preparation preserving cortical inputs

Abstract: 1. The morphology, electrical membrane properties, and corticostriatal excitatory postsynaptic potentials (EPSPs) of two groups of neostriatal projection cells, patch cells, and matrix spiny cells were compared in the rat by the use of an in vitro slice preparation that preserves inputs from medial agranular cortex. Spiny cells were stained intracellularly with biocytin and identified as belonging to the patch (striosomal) compartment or to the matrix by immunohistochemistry for the 28 kD calcium-binding protein calbindin on the same sections. 2. Patch and matrix neurons had very similar axonal and dendritic morphology. Both patch and matrix cells extended their dendrites and local axon collaterals almost exclusively in their respective compartments. Patch cells and most matrix cells had local axon collaterals within or near the parent dendritic domain. However there was a class of matrix cells that extended axon collaterals over a much wider portion of the neostriatum but still restricted to the matrix compartment. 3. Input resistance and membrane time constant were estimated from the membrane response to intracellularly applied current pulses. The average values of matrix cells were and 8.41 ms. The values of patch cells were 31.8 M omega and 8.19 ms and were within the range of those of matrix cells. Both types of cells showed the same kinds of membrane nonlinearities when tested with the use of current pulses. Input resistance and time constant were both strongly affected by a fast anomalous rectification and were thus voltage-dependent, decreasing with membrane polarization. Slow ramplike depolarizing responses were observed in response to depolarizing current steps. 4. Repetitive firing was examined with the use of depolarizing current pulses. In both types of spiny cells, trains of action potentials showed little adaptation of spike frequency and linearly increased with current intensities less than 1 nA. The slopes frequency, calculated from the first and second intervals, were 115.0 and 107.2 Hz/nA, respectively, for matrix cells and 86.0 and 82.8 Hz/nA for patch cells. 5. Stimulation of the medial agranular cortex induced EPSPs in some striatal cells in both compartments. EPSP in matrix cells often showed both short-latency and long-latency components, corresponding to two early components of the response observed in vivo. Some matrix cells, and all patch cells, showed only the longer latency EPSP component. The average latency was 6.3 ms in matrix cells and 9.1 ms in patch cells. The relationship between EPSP amplitude and membrane potential was nonlinear, with EPSP amplitude and duration increasing with decreasing membrane polarization.(ABSTRACT TRUNCATED AT 400 WORDS)

Coronal positioning of existing gingiva: short term results in the treatment of shallow marginal tissue recession.

Abstract: Although not a new procedure, coronal positioning of existing gingiva may be used to enhance esthetics and reduce sensitivity. Unfortunately when recession is minimal and the marginal tissue is healthy, many periodontists do not suggest treatment. This article outlines a simple surgical technique with the criteria for its use which results in a high degree of predictability and patient satisfaction.

Reference standards for flow cytometry and application in comparative studies of nuclear DNA content

Abstract: Nuclear DNA mass in cells from a reference species can be used to obtain high-resolution estimates of DNA mass from a target species. In our study of DNA mass in cells from 45 selected species, representing each of the major vertebrate classes, we have obtained values of from 1.5 to 110.0 pg of DNA. Because values in or near this range would be expected in the study of nuclear DNA mass in vertebrates and other organisms, the species in this report can provide a useful catalogue of references for comparative studies of DNA.

DNA topoisomerase II-mediated interaction of doxorubicin and daunorubicin congeners with DNA.

Abstract: Three groups of doxorubicin and daunorubicin analogues, differing by their substituents on the chromophore and sugar moieties, were used in this study. The 3'-N-unsubstituted (Group 1), 3'-N-acyl (Group 2), and 3'-N-alkyl (Group 3) analogues were tested for: (a) in vivo antitumor activity and in vitro cytotoxicity; (b) cellular or tissue uptake and metabolic conversion; (c) strength of DNA intercalation; and (d) interaction with DNA topoisomerase II (topo-II). Compounds of Group 1 were cytotoxic, were strongly intercalative, and, except for those with C-14 side chain substitution, induced the formation of topo-II-DNA cleavable complexes. As shown previously, esterolysis of C-14-acyl substituents was required to yield a metabolite which can interact with topo-II in the purified system. The C-14-substituted compounds of Group 2 and their C-14-unsubstituted metabolites were cytotoxic. These drugs were weak intercalators, and the C-14-unsubstituted cogeners induced cleavable complex formation in the purified system, but with reduced potency relative to doxorubicin. The type of the 3'-N-position substituent determined whether Group 3 analogues were cytotoxic and strong intercalators, or less active and nonintercalating. Although C-14-unsubstituted intercalators of Group 3 did not form cleavable complexes in the purified system, they were cytotoxic. The study shows that DNA intercalation is required but not sufficient for the activity by topo-II-targeted anthracyclines. In addition to the planar chromophore which is involved in intercalation, two other domains of the anthracycline molecule are important for the interaction with topo-II: (a) substitution of the C-14 position totally inhibits drug activity in the purified system, but enhances cytotoxicity by aiding drug uptake and presumably acting on other cellular targets; and (b) substitutions on the 3'-N position of the sugar ring can, depending on the nature of the substituent, inhibit intercalation and/or topo-II-targeting activity. These findings may provide guidance for the synthesis and development of new active analogues.

Role of reactive oxygen species in reperfusion injury of the rabbit lung.

Abstract: We have developed a model of reperfusion injury in Krebs buffer-perfused rabbit lungs, characterized by pulmonary vasoconstriction, microvascular injury, and marked lung edema formation. During reperfusion there was a threefold increase in lung superoxide anion (O2-) production, as measured by in vivo reduction of nitroblue tetrazolium, and a twofold increase in the release of O2- into lung perfusate, as measured by reduction of succinylated ferricytochrome c. Injury could be prevented by the xanthine oxidase inhibitor allopurinol, the O2- scavenger SOD, the hydrogen peroxide scavenger catalase, the iron chelator deferoxamine, or the thiols dimethylthiourea or N-acetylcysteine. The protective effect of SOD could be abolished by the anion channel blocker 4,4'-diisothiocyano-2,2'-stilbene disulfonic acid, indicating that SOD consumes O2- in the extracellular medium, thereby creating a concentration gradient favorable for rapid diffusion of O2- out of cells. Our results extend information about the mechanisms of reperfusion lung injury that have been assembled by studies in other organs, and offer potential strategies for improved organ preservation, for treatment of reperfusion injury after pulmonary thromboembolectomy, and for explanation and therapy of many complications of pulmonary embolism.

Inhibition of rat mesangial cell mitogenesis by nitric oxide-generating vasodilators

Abstract: Recent studies indicate that endothelium-derived relaxing factor (EDRF) may be identical with nitric oxide (NO). The purpose of this study was to investigate the antimitogenic effect of NO-generating drugs in cultured mesangial cells. S-nitroso-N-acetylpenicillamine, sodium nitroprusside, and isosorbide dinitrate, which generate NO, dose dependently inhibited serum-stimulated DNA synthesis. All three drugs also inhibited the rate of cell proliferation, whereas sodium nitroprusside and S-nitroso-N-acetylpenicillamine decreased cell density at confluence. The antimitogenic activity of S-nitroso-N-acetylpenicillamine was labile in culture medium and could be inhibited by hemoglobin, supporting the view that NO, in free or bound form, was the ultimate effector. All three vasodilators increased cellular guanosine 3',5'-cyclic monophosphate (cGMP) levels dose dependently; moreover, 8-bromo-cGMP mimicked the effects of the NO-generating drugs, suggesting that cGMP may be an intracellular mediator of antimitogenesis. The growth-inhibitory effect of S-nitroso-N-acetylpenicillamine was reversible and was not due to cell toxicity as shown by several criteria of cell viability. The results raise the possibility that EDRF/NO may be a modulator of mesangial cell growth in vivo.

Peripheral primitive neuroectodermal tumor (peripheral neuroepithelioma) in children. A review of the St. Jude experience and controversies in diagnosis and management.

Abstract: All patients diagnosed with primitive neuroectodermal tumor (PNET) and extraosseous Ewing's sarcoma in one institution between 1962 and 1987 were reviewed. Of the 26 cases studied, 16 had been diagnosed originally as PNETs, seven tumors were rediagnosed as PNET or EOE by histologic review, and three tumors had an original diagnosis of extraosseous Ewing's sarcoma. To determine whether these diagnoses determine a group of tumors with unique biologic behavior and identifiable pathologic characteristics, clinical and treatment response data were compiled, and electron microscopic and immunohistochemical studies were done for those patients with adequate samples. With combined modality therapy, this group achieved a substantially shorter disease control interval than patients with disseminated osseous Ewing's sarcoma or disseminated neuroblastoma--10.8 months versus 17 months and 16 months, respectively. The pattern of relapse and distant spread also differed among these tumor types. Immunohistochemical studies (for example, neuron-specific enolase and beta 2 microglobulin) were helpful in confirming the diagnosis but were not definitive in themselves. Tentative diagnostic criteria are proposed for use in studies designed to provide further information on the nature and treatment of PNET. Some of the controversies regarding diagnosis are discussed. The authors propose a uniform approach to treatment of extraosseous Ewing's sarcoma and PNET in order to try to clarify their relation.

Cholesterol is required for secretion of very-low-density lipoprotein by rat liver

Abstract: To study potential effects of hepatic cholesterol concentration on secretion of very-low-density lipoprotein (VLDL) by the liver, male rats were fed on unsupplemented chow, chow with lovastatin (0.1%), or chow with lovastatin (0.1%) and cholesterol (0.1%) for 1 week. Livers were isolated from these animals and perfused in vitro, with a medium containing [2-14C]acetate, bovine serum albumin and glucose in Krebs-Henseleit buffer, and with an oleate-albumin complex. With lovastatin feeding, the hepatic concentrations of cholesteryl esters and triacylglycerols before perfusion were decreased, although free cholesterol was unchanged. However, hepatic secretion of all the VLDL lipids was decreased dramatically by treatment with lovastatin. Although total secretion of VLDL triacylglycerol, phospholipid, cholesterol and cholesteryl esters was decreased, the decrease in triacylglycerol was greater than that in free cholesterol or cholesteryl esters, resulting in secretion of a VLDL particle enriched in sterols relative to triacylglycerol. In separate studies, the uptake of VLDL by livers from control animals or animals treated with lovastatin was measured. Uptake of VLDL was estimated by disappearance of VLDL labelled with [1-14C]oleate in the triacylglycerol moiety, and was observed to be similar in both groups. During perfusion, triacylglycerol accumulated to a greater extent in livers from lovastatin-fed rats than in control animals. The depressed output of VLDL triacylglycerols and the increase in triacylglycerol in the livers from lovastatin-treated animals was indicative of a limitation in the rate of VLDL secretion. Addition of cholesterol (either free cholesterol or human low-density lipoprotein) to the medium perfusing livers from lovastatin-fed rats, or addition of cholesterol to the diet of lovastatin-fed rats, increased the hepatic concentration of cholesteryl esters and the output of VLDL lipids. The concentration of cholesteryl esters in the liver was correlated with the secretion of VLDL by the liver. These data suggest that cholesterol is an obligate component of the VLDL required for its secretion. It is additionally suggested that cholesteryl esters are in rapid equilibrium with a small pool of free cholesterol which comprises a putative metabolic pool available and necessary for the formation and secretion of the VLDL. Furthermore, the specific radioactivity (d.p.m./mumol) of the secreted VLDL free cholesterol was much greater than that of hepatic free cholesterol, suggesting that the putative hepatic metabolic pool is only a minor fraction of total hepatic free cholesterol.

Primary repair of colon wounds. A prospective trial in nonselected patients.

Abstract: 102 patients with penetrating intraperitoneal colon injuries were entered into a prospective study. Colon wound management was undertaken without regard to associated injuries or amount of fecal contamination. Primary repair was performed in 83 patients, segmental resection with anastomosis in 12, and resection with end colostomy in 7. There were no suture line failures in the primary repair group, and one suture line failure in the anastomosis group. The one failure was in a patient who underwent repeated explorations for bleeding before the leak occurred. The septic complication rate was 33% of the entire series and was unrelated to primary repair. Logistic regression analysis to identify risk factors for sepsis included transfusion greater than or equal to 4 units (p less than 0.02), more than two associated injuries (p less than 0.04), significant contamination (p less than 0.05), and increasing colon injury severity scores (p less than 0.02). The method of colon wound management, location and mode of injury, presence of hypotension (BP less than 90), and age did not significantly contribute to sepsis. We conclude that nearly all penetrating colon wounds can be repaired primarily or with resection and anastomosis, regardless of risk factors.

Hypertension in elderly patients.

Abstract: Purpose:To synthesize and analyze new information on the epidemiology, pathophysiology, and management of hypertension in the elderly to guide physicians making treatment decisions. Data I...

Coordinate regulation of transforming growth factor beta gene expression and cell proliferation in hamster lungs undergoing bleomycin-induced pulmonary fibrosis.

Abstract: The number of mesenchymal cells, as well as their ability to synthesize extracellular matrix (ECM) components, greatly increase in the interstitium of fibrotic lungs We have previously shown that the transcription of type I procollagen and fibronectin genes in the lungs is preferentially elevated during the early stages of bleomycin-induced pulmonary fibrosis (Raghow, R, S Lurie, J M Seyer, and A H Kang 1985, J Clin Invest 76:1734-1739 Since a cytokine-like transforming growth factor beta (TGF beta) that is capable of enhancing mesenchymal cell proliferation and ECM synthesis could be potentially involved in this process, we investigated the temporal relationship between the regulation of TGF beta gene transcription and cellular proliferation in the bleomycin-treated hamster lungs We observed a transient 5-7-fold increase in the accumulation of TGF beta transcripts, a concomitant 3-4-fold elevation in the cellular proliferation, and 8-10-fold stimulation of DNA synthesis in these lungs; all three parameters peaked around day 10 after bleomycin administration Based on these results, we conclude that regulation of TGF beta gene expression may contribute significantly to the early events that lead to bleomycin-induced pulmonary fibrosis

Corticotropin-releasing factor attenuates interleukin 1-induced sleep and fever in rabbits

Abstract: Interleukin 1 (IL-1), a key mediator of the acute phase response, stimulates hypothalamic corticotropin-releasing factor (CRF) release. The CRF-adrenocorticotrophic hormone (ACTH)-glucocorticoid axis is a feedback for peripheral production and action of IL-1. Effects of intracerebroventricularly administered CRF on rabbit sleepwake activity, brain temperature (Tbr), and behavior and on the central effects of IL-1 [fever and excess non-rapid-eye-movement sleep (NREMS)] were studied. CRF (0.1-1.25 micrograms) dose dependently decreased NREMS and enhanced wakefulness. IL-1-induced excess NREMS was inhibited by CRF. Rapid-eye-movement sleep (REMS) suppressed by IL-1 was partially restored by 0.1 or 0.5 microgram CRF, although CRF itself did not promote REMS. Behavioral effects of intracerebroventricular CRF were relatively small, although 1.25 micrograms abolished ingestion for 3 h, suppressed rearing behavior, and increased sitting behavior. Tbr increased after CRF injection alone. After IL-1 pretreatment, however, 0.1 and 0.5, but not 1.25, micrograms CRF reduced IL-1-induced fever after several hours. These results implicate IL-1-induced CRF release as part of a negative-feedback mechanism attenuating not only peripheral IL-1 actions but also its central effects.

Clinical manifestations of ganglioneuroma

Abstract: Ganglioneuroma may occur spontaneously or after therapy for neuroblastoma. This lesion may be metastatic or unresectable in the primary site. The rarity of this situation and lack of understanding of the biology of this benign condition may lead to extensive, potentially life-threatening attempts at surgical resection or the futile use of chemotherapy or radiotherapy to try to cause regression or control growth. The authors present here several cases which demonstrate the multiple presentations of ganglioneuroma and the potential problems which may arise in their management.

Distribution of mu, delta, and kappa opiate receptor types in the forebrain and midbrain of pigeons

Abstract: Ligands that are highly specific for the mu, delta, and kappa opiate receptor binding sites in mammalian brains have been identified and used to map the distribution of these receptor types in the brains of various mammalian species. In the present study, the selectivity and binding characteristics in the pigeon brain of three such ligands were examined by in vitro receptor binding techniques and found to be similar to those reported in previous studies on mammalian species. These ligands were then used in conjunction with autoradiographic receptor binding techniques to study the distribution of mu, delta, and kappa opiate receptor binding sites in the forebrain and midbrain of pigeons. The autoradiographic results indicated that the three opiate receptor types showed similar but not identical distributions. For example, mu, delta, and kappa receptors were all abundant within several parts of the cortical-equivalent region of the telencephalon, particularly the hyperstriatum ventrale and the medial neostriatum. In contrast, in other parts of the cortical-equivalent region of the avian telencephalon, such as the dorsal archistriatum and caudal neostriatum, only kappa receptors appeared to be abundant. Within the basal ganglia, all three types of opiate receptos were abundant in the striatum and low in the pallidum. Within the diencephalon, kappa and delta binding was high in the dorsal and dorsomedial thalamic nuclei, but the levels of all three receptor types were generally low in the specific sensory relay nuclei of the thalamus. Kappa binding and delta binding were high, but mu was low in the hypothalamus. Within the midbrain, all three receptor types were abundant in both the superficial and deep tectal layers, in periventricular areas, and in the tegmental dopaminergic cell groups. In many cases, the distribution of opiate receptors in the pigeon forebrain generally showed considerable overlap with the distribution of opioid peptide-containing fiber systems (for example, in the striatal portion of the basal ganglia), but there were some clear examples of receptor-ligand mismatch. For example, although all three receptor types are very abundant in the hyperstriatum ventrale, opioid peptide-containing fibers are sparse in this region. Conversely, within the pallidal portion of the basal ganglia, opioid peptide-containing fibers are abundant, but the levels of opiate receptors appear to be considerably lower than would be expected. Thus, receptorligand mismatches are not restricted to the mammalian brain, since they are a prominent feature of the organization of the brain opiate systems in pigeons. Although the precise functional significance of such mismatches will require further elucidation, it nonetheless appears likely that the endogenous opioid peptides of the avian brain act through the opiate receptors whose distribution is described in the present paper.