PubMed Health⌕ Search

Biomedical subjects

R F Lodato

Publications and source records attributed to R F Lodato.

At least 19 recordsLinked to original sources
PubMed1999

Roles of IL-1 and TNF in the decreased ileal muscle contractility induced by lipopolysaccharide.

Gastrointestinal stasis during sepsis may be associated with gastrointestinal smooth muscle dysfunction. Endotoxin [lipopolysaccharide (LPS)] impairs smooth muscle contraction, in part through inducible nitric oxide synthase (NOS II) and enhanced nitric oxide production. We studied the roles of tumor necrosis factor-alpha (TNF) and interleukin-1 (IL-1) in this process by using TNF binding protein (TNFbp) and IL-1 receptor antagonist (IL-1ra). Rats were treated with TNFbp and IL-1ra, or their vehicles, 1 h before receiving LPS or saline. At 5 h after LPS, contractility was measured in strips of ileal longitudinal smooth muscle, and NOS II activity was measured in full-thickness segments of ileum. LPS decreased maximum stress (mean +/- SE) from 508 +/- 55 (control) to 355 +/- 33 g/cm2 (P < 0.05). Pretreatment with TNFbp plus IL-1ra prevented the LPS-induced decrease. Separate studies of TNFbp alone or IL-1ra alone indicated that, at the doses and timing used, TNFbp was more effective. LPS also increased NOS II activity by >10-fold (P < 0.01) over control. This increase was prevented by TNFbp plus IL-1ra (P = not significant vs. control). We conclude that the LPS-induced increase in NOS II activity and the decrease in ileal muscle contractility are mediated by TNF and IL-1.

Animals↗
PubMed1996

Decreased ileal muscle contractility and increased NOS II expression induced by lipopolysaccharide.

This study was designed to determine if an increase in nitric oxide synthase (NOS) activity induced by lipopolysaccharide (LPS) is associated with increases in NOS II protein and mRNA abundance and with altered ileal longitudinal muscle contractility. Strips of muscle taken from LPS-treated, but not control, animals exhibited reduced in vitro contractility when L-arginine was a component of the physiological salt solution. This reduction was reversed by N omega-nitro-L-arginine (L-NNA), a competitive inhibitor of NOS. Full-thickness segments of jejunum, ileum, and colon taken 5 h after LPS injection exhibited increased NOS activity, NOS II immunoreactivity, and NOS II mRNA abundance. Increased NOS II immunoreactivity and mRNA abundance also were detected in ileal muscle strips taken from LPS-treated animals. These data confirm the reported effects of LPS on intestinal NOS activity and indicate that it can be attributed, at least in part, to an increase in NOS II mRNA and protein abundance. Furthermore, the data suggest that an LPS-induced increase in NOS II may lead to a decrease in ileal muscle contractility.

Animals↗
PubMed1995

Hemodynamic evaluation of recombinant human tumor necrosis factor (TNF)-alpha, TNF-SAM2 and liposomal TNF-SAM2 in an anesthetized dog model.

We have evaluated the hemodynamic effects of systemically administered recombinant human tumor necrosis factor (TNF)-alpha, TNF-SAM2 and liposome-bound TNF-SAM2 in an anesthetized mongrel dog model. A dose of 10 micrograms TNF protein/kg of each formulation was injected in a peripheral vein and mean systemic arterial pressure (SAP), heart rate (HR) and cardiac output (CO) were measured. TNF-alpha induced a marked drop in SAP in all three dogs (mean decrease = 59.3 +/- 5.2 mm Hg; to 61.5% of baseline; p = 0.008); whereas TNF-SAM2 caused a smaller and transient drop in SAP in four dogs (mean decrease = 25.5 +/- 10.1 mm Hg; to 81.2% of baseline; p = 0.086). In three dogs administered liposome-bound TNF-SAM2, which retains antitumor activity in vivo, a net slight hypertensive phase and sustained elevated CO occurred, followed by a return to an essentially normotensive state (101.0% of baseline SAP). This model demonstrates that the principal acute systemic toxicity of TNF, i.e., hypotension, can be markedly attenuated by liposomal formulation of a second-generation TNF.

Animals↗
PubMed1995

Interrelationship of breath components in neighboring breaths of normal eupneic subjects.

To determine the fraction of variational activity that is correlated on a breath-to-breath basis from uncorrelated random fluctuations, we performed autocorrelation analysis in 33 normal subjects during resting breathing. A calibrated inductive plethysmograph was used to nonobtrusively record 700 breaths in each subject. The group mean autocorrelation coefficients at a lag of 1 breath for each of the three primary breath components, tidal volume (VT), inspiratory time (TI), and expiratory time (TE), were significantly different from zero (p < 0.001). The autocorrelation coefficients for VT, 0.295 +/- 0.148 (SD), and TE, 0.259 +/- 0.121, were greater than that for TI, 0.201 +/- 0.135 (p < 0.001 and p < 0.01, respectively). The autocorrelation coefficients for each breath component remained significant for approximately 3 consecutive breaths (p < 0.001), indicating the presence of "short-term memory." Cross-correlation analysis revealed significant interrelationships (p < 0.001) for all component irrespective of which component was leading or following, with the exception of the pairing of VT in the leading breath and TI in the subsequent breath. In conclusion, in resting healthy subjects breath components display considerable breath-to-breath variability that is not completely random in nature, but which, instead, has a significant fraction of structured correlated variational activity.

Adult↗
PubMed1994

Effects of dobutamine on oxygen transport and consumption in the adult respiratory distress syndrome.

OBJECTIVE: To determine if oxygen consumption (VO2) in patients with adult respiratory distress syndrome (ARDS) is dependent on, and thus limited by, oxygen transport (TO2) rather than O2 demand. DESIGN: Prospective study. SETTING: Intensive care unit of a tertiary referral center. PATIENTS: 12 patients with ARDS and sepsis syndrome. INTERVENTIONS: Routine intensive care unit monitoring including pulmonary and radial artery catheters. MEASUREMENTS: Dobutamine was used to increase cardiac output, thereby directly varying TO2 under conditions of constant O2 demand. After baseline measurements of TO2 and VO2, dobutamine was infused intravenously at progressively increasing doses of 5, 10, 15 and 20 micrograms/kg/min and measurements of TO2 and VO2 were repeated after 30 min at each dose. RESULTS: Dobutamine increased TO2 in 8 of the 12 patients, by 29% at 5 micrograms/kg/min and by 45% (net) at 10 micrograms/kg/min, but not at higher doses. In these 8 patients dobutamine also increased VO2 by 15% at 5 micrograms/kg/min, but did not further increase VO2 at higher doses. There was no correlation between baseline blood lactate concentration and the response of either TO2 or VO2 to dobutamine. CONCLUSIONS: In some but not all patients with ARDS and sepsis syndrome, short-term infusion of low-dose dobutamine can increase both TO2 and VO2. Achievement of a TO2-independent level of VO2 could not be convincingly demonstrated in any individual patient. The response of TO2 and VO2 to dobutamine could not be predicted from baseline blood lactate concentration. Determination of the impact on patient outcome of a more prolonged infusion of dobutamine requires further study.

Adult↗
PubMed1994

Nitric oxide is involved in muscle relaxation but not in changes in short-circuit current in rat ileum.

L-Arginine (L-Arg)-nitric oxide (NO) pathways in rat ileum were studied in an Ussing chamber modified so that a strain gauge transducer could be attached longitudinally on the serosal side of the intestine. Ileal segments from 22 rats were mounted as flat sheets and voltage clamped at zero transmural potential (PD). Changes in short-circuit current (delta ISC) in the absence of carbachol and longitudinal muscle relaxations in the presence of carbachol in response to transmural field stimulation (TMS; 5-s trains of impulses, 0.4-ms impulse duration, 1-10 Hz) were recorded during a control period, in the presence of N omega-nitro-L-arginine (L-NNA; 10(-4) M), and in the presence of L-Arg after treatment with L-NNA. In the control period, the delta ISC and muscle relaxation were frequency dependent with maximal responses generated at a frequency of 10 Hz. Tetrodotoxin (5 x 10(-6) M) blocked muscle relaxation and decreased delta ISC by 94% during TMS at 10 Hz. L-NNA blocked the muscle relaxation induced by TMS but failed to alter delta ISC. Muscle relaxation to TMS was restored dose dependently by L-Arg. In segments from another group of eight rats, saturated NO solutions relaxed the muscle but failed to change ISC either in the presence or absence of carbachol. These results support a role for NO as a neurotransmitter mediating relaxation of ileal smooth muscle but not mediating changes in epithelial ISC.

Animals↗
PubMed1993

Adult intracardiac rhabdomyoma resembling the extracardiac variant.

Rhabdomyomas are benign striated muscle neoplasms that may assume a number of characteristic histologic patterns. These lesions may be classified as cardiac or extracardiac on the basis of their location and histology. We present a case of large intracardiac mass with the morphologic features of an extracardiac rhabdomyoma occurring in an adult female.

Adult↗
PubMed1993

Response time, autonomic mediation, and reversibility of hyperoxic bradycardia in conscious dogs.

Normobaric hyperoxia decreases heart rate (HR) in humans and animals. This study explored the mechanisms of hyperoxic bradycardia by examining its response time, autonomic neural mediation, and reversibility in conscious dogs. Five trained mongrel dogs breathed from a mask as the inspired gas was alternated between air and O2 for multiple cycles, and continuous time series records of HR and oxyhemoglobin saturation were recorded on a digital computer and analyzed by the technique of ensemble averaging. Hyperoxia decreased HR by 9% (P < 0.001), but only gradually, requiring 5 min to reach steady state. This delay was much longer than the time required for hyperoxic respiratory depression (10-20 s), a response known to be mediated by chemoreceptor reflexes. The bradycardia was sustained for > or = 30 min. On return to normoxia, HR gradually returned toward, but failed to reach, the baseline HR, suggesting incomplete reversibility of the response. However, in control experiments without hyperoxic challenge, HR showed a slow continuous downward trend that was sufficient to account for the apparent incomplete reversibility of hyperoxic bradycardia. Hyperoxic bradycardia was unaffected by beta-adrenergic blockade but was completely prevented by muscarinic cholinergic blockade. We conclude that 1) hyperoxia-induced bradycardia in conscious dogs is mediated by efferents of the vagus nerve; 2) its afferent pathway remains unknown, but its long response time suggests mechanisms other than chemoreceptor reflexes or other known neural reflexes; and 3) it is completely reversible.

Adrenergic beta-Antagonists↗
PubMed1993

Skeletal dysplasia in perinatal lethal osteogenesis imperfecta. A complex disorder of endochondral and intramembranous ossification.

Osteogenesis imperfecta (OI) Type II is a rare heritable disorder of bone matrix that results in catastrophic congenital skeletal dysplasia. Two cases of OI Type II had symmetric rhizomelic skeletal dysplasia apparent on ultrasound at 16 and 20 weeks' gestation. Histologic and histochemical studies performed on skeletal tissue from fetal autopsies showed the following: (1) abnormal growth plate tissue characterized by failure of formation of primary bony spongiosa; (2) persistence of calcified cartilage bars in the diaphysis; (3) metaphyseal microfractures; (4) abundant cartilaginous fracture callus; (5) absence of bony callus; (6) failure of formation of intramembranous cortical diaphyseal bone; (7) angulation of long bones in portions of the metadiaphyses bordered by fracture callus; and (8) mechanical failure of the perichondral ring of LaCroix with a normal fibrous ossification groove of Ranvier. These findings suggest that skeletal dysplasia in OI Type II results from the action of muscular forces on a skeleton weakened by a complex disorder of endochondral and intramembranous ossification. The paucity of primary metaphyseal trabeculae and subperiosteal cortical bone leads to pathologic fractures of the immature fiber bone and an imperfect attempt at fracture repair. Angulation and shortening of long bones occurs between numerous sites of focal endochondral fracture callus. Mechanical failure of the fibrous perichondral ring leads to further collapse and shortening without obvious functional impairment of the fibrous ossification groove. Perinatal lethal OI provides insight into how a molecular disorder predominantly of Type I collagen metabolism results in pathology of numerous tissues, leading to severe skeletal dysplasia without primarily affecting chondrogenesis.

Bone Diseases, Developmental↗
PubMed1992

N omega-amino-L-arginine, an inhibitor of nitric oxide synthase, raises vascular resistance but increases mortality rates in awake canines challenged with endotoxin.

Inhibitors of nitric oxide synthase (NOS) have been reported to increase mean arterial pressure in animal models of sepsis and recently have been given to patients in septic shock. However, controlled studies to determine the effects of these agents on cardiovascular function and survival in awake animal models of sepsis have not been reported. To examine the therapeutic potential of NOS inhibition in septic shock, we challenged canines with endotoxin (2 or 4 mg/kg i.v.) and treated them with either normal saline or N omega-amino-L-arginine (10 or 1 mg/kg/h), the most specific inhibitor available for the isoform of NOS implicated in septic shock. Endotoxemic animals treated with N omega-amino-L-arginine (n = 11) had higher systemic and pulmonary vascular resistance indices (SVRI and PVRI, p less than or equal to 0.033) and decreased heart rates (p = 0.009), cardiac indices (CI, p = 0.01), oxygen delivery indices (p = 0.027), and oxygen consumption indices (p = 0.046) compared with controls (n = 6). Moreover, N omega-amino-L-arginine increased mortality rates after endotoxin challenge (10 of 11 vs. 1 of 6 controls, p = 0.005). Administration of L-arginine did not improve survival or alter the cardiopulmonary effects of N omega-amino-L-arginine, which suggests that inhibition of NOS may not have been competitive. In normal animals, N omega-amino-L-arginine alone (n = 3) increased SVRI (p = 0.0008) and mean arterial pressure (p = 0.016), and decreased CI (p = 0.01) compared with saline-treated controls (n = 3), but, at the high dose, also produced neuromuscular rigidity and seizure-like activity that was not apparent in the endotoxemic model. Thus, the mortality rate from endotoxemia increased either because of NOS inhibition per se or because of properties unique to N omega-amino-L-arginine, or both.

Amino Acid Oxidoreductases↗
PubMed1992

Inhibition of interleukin-1-alpha-induced nitric oxide synthase in vascular smooth muscle and full reversal of interleukin-1-alpha-induced hypotension by N omega-amino-L-arginine.

BACKGROUND: Interleukin-1-alpha (IL-1) is a cytokine with potentially therapeutic immunoproliferative and tumoricidal activities. Preliminary clinical studies suggest that use of IL-1 may be restricted by dose-limiting hypotension. PURPOSE: The purpose of this study was to investigate the role of nitric oxide (NO.) as a possible mediator of this hypotension. METHODS: Cytokine-treated rat aortic smooth muscle cells were assayed for nitrite production, a stable breakdown product of nitric oxide. Nitric oxide synthase from smooth muscle cells was partially characterized in cytosol preparations using a novel Fe(2+)-myoglobin method to test for nitric oxide production. To determine the role of NO. on the immunorestorative and antineoplastic activity of IL-1, N omega-amino-L-arginine (NAA) or N omega-monomethyl-L-arginine (NMA), inhibitors of nitric oxide synthase, were added to either cultures of IL-1-dependent T cells or A375 melanoma cells exposed to IL-1. To investigate the effects of NAA in vivo, pentobarbital anesthetized dogs, which were made hypotensive by administration of IL-1, received a single intravenous bolus dose of NAA. The effects of NAA were then reversed by the administration of L-arginine. RESULTS: Our results show that cultured IL-1-activated rat aortic smooth muscle cells synthesize nitric oxide, a potent vasodilator. Induction of nitric oxide synthase is augmented by interferon-gamma and blocked by IL-1 receptor antagonist and by inhibitors of RNA or protein synthesis. Nitric oxide synthesis by IL-1-activated smooth muscle cells is inhibited by NAA, NMA, and N omega-nitro-L-arginine (NNA) with ED50 (i.e., effective dose for 50% inhibition) values of 20, 60, and 1000 microM, respectively; this rank order of inhibition is characteristic of an agonist-unregulated, inducible isoform of nitric oxide synthase. In smooth muscle cells, inhibition of NO. synthesis by NAA is reversed by excess L-arginine. Consistent with the induction of unregulated NO. synthesis in vascular smooth muscle in vivo, administration of IL-1 (50 micrograms/kg) to dogs caused a 33.5% decrease in systemic vascular resistance and a 28% decrease in blood pressure within 3 hours. Subsequent administration of NAA (20 mg/kg) rapidly and completely reversed the hypotension and increased systemic vascular resistance; these effects of NAA were reversed by L-arginine. Neither the immunoproliferative nor the tumoricidal activity of IL-1 was diminished by NAA. CONCLUSIONS: Our results indicate that (a) vascular smooth muscle is a likely source as well as a target of IL-1-induced NO. synthesis, causing vasodilatation and hypotension, (b) nitric oxide synthase inhibitors can fully reverse this hypotension, and (c) the therapeutically useful properties of IL-1 are not diminished by nitric oxide synthase inhibitors. IMPLICATIONS: Administration of inhibitors of nitric oxide synthase can reverse the pathological cardiovascular effects of IL-1 at concentrations that do not interfere with the potentially useful immunoproliferative or tumoricidal effects of this cytokine. In the context of the current clinical trials of IL-1, this finding would represent a very significant advantage.

Amino Acid Oxidoreductases↗
PubMed1991

Scrotal carcinoid. Presenting manifestation of multiple lesions in the small intestine.

A middle-aged man presented with a paratesticular carcinoid tumor, his first manifestation of multiple carcinoid tumors of the small bowel. Of the nine carcinoids reported in the English-language literature as metastatic to the scrotum, five simulated a primary lesion. Although the bulk of scrotal carcinoids arise in the testis, the differential diagnosis always should include metastasis from an extrascrotal source.

Carcinoid Tumor↗
PubMed1991

Chylothorax as presenting manifestation of adenocarcinoma with probable gastric primary.

Chylothorax is an unusual complication of various malignant neoplasms, generally lymphomas. The few reported cases of chylothorax with gastric and other abdominal malignancies have involved large abdominal masses with prominent adenopathy and chylous ascites. We describe a patient in whom chylothorax was the presenting manifestation of an adenocarcinoma with probable gastric primary, developing prior to any clinical or radiologic evidence of tumor.

Adenocarcinoma, Mucinous↗
PubMed1990

Reversal of endotoxin-mediated shock by NG-methyl-L-arginine, an inhibitor of nitric oxide synthesis.

Septic shock is a life-threatening condition that results from exposure to bacterial endotoxin. It is manifested by cardiovascular collapse and mediated by the release of cytokines such as tumor necrosis factor. Some of these cytokines cause the release of vasoactive substances. In the present study, administration of 40 microgram/kg of bacterial endotoxin to dogs caused a 33% decrease in peripheral vascular resistance and a 54% fall in mean arterial blood pressure within 30 to 90 minutes. Vascular resistance and systemic arterial pressure returned to normal within 1.5 minutes after intravenous administration of NG-methyl-L-arginine (20 mg/kg), a potent and selective inhibitor of nitric oxide synthesis. L-Arginine reversed the effect of L-NMA and restored the endotoxin-induced hypotension. Although NG-methyl-L-arginine injection increased blood pressure in control dogs, the hypertensive effect was much greater in endotoxemic dogs (24.8 +/- 2.7 mmHg vs 47.8 +/- 6.8 mmHg, p = 0.01, n = 4). NG-Methyl-L-arginine caused only a modest increase in blood pressure in dogs made hypotensive by continuous intravenous infusion of nitroglycerin (17.1 +/- 5.0 mm Hg, n = 3). These findings suggest that nitric oxide overproduction is an important contributor to endotoxic shock. Moreover, our findings demonstrate for the first time, the utility of nitric oxide synthesis inhibitors in endotoxic shock and suggest that such inhibitors may be of therapeutic value in the treatment of septic shock.

Animals↗
PubMed1990

Effects of normobaric hyperoxia on hemodynamics and O2 utilization in conscious dogs.

Normobaric hyperoxia decreased resting whole-body O2 consumption in conscious dogs by equal (Fick) contributions from decreases in cardiac output and in the arterial-venous difference in O2 content. The decrease in O2 consumption was fully developed by 20 min, was maintained for at least 1 h, and was both reversible and reproducible. Hyperoxia also decreased heart rate, right and left ventricular work rates (and therefore, presumably myocardial O2 consumption), and pulmonary vascular resistance; and increased systemic vascular resistance and right atrial pressure. Paradoxically, hyperoxia did not change O2 delivery. This latter observation together with the decrease in O2 consumption produced a unique vertical orientation to the O2 consumption-delivery relationship induced by hyperoxia. It is concluded that hyperoxia may decrease metabolic rate and substantially alter hemodynamics, which may have important implications for understanding the metabolic regulation of oxygen utilization and for the medical and nonmedical uses of oxygen.

Animals↗
PubMed1990

NG-methyl-L-arginine inhibits tumor necrosis factor-induced hypotension: implications for the involvement of nitric oxide.

Clinical assessment of the activity of tumor necrosis factor (TNF) against human cancer has been limited by a dose-dependent cardiovascular toxicity, most frequently hypotension. TNF is also thought to mediate the vascular collapse resulting from bacterial endotoxin. The present studies address the mechanism by which TNF causes hypotension and provide evidence for elevated production of nitric oxide, a potent vasodilator initially characterized as endothelium-derived relaxing factor. Nitric oxide is synthesized by several cell types, including endothelial cells and macrophages, from the guanidino nitrogen of L-arginine; the enzymatic pathway is competitively inhibited by NG-methyl-L-arginine. We found that hypotension induced in pentobarbital-anesthetized dogs by TNF (10 micrograms/kg, i.v., resulting in a fall in mean systemic arterial pressure from 124.7 +/- 7 to 62.0 +/- 22.9 mmHg; 1 mmHg = 133 Pa) was completely reversed within 2 min following administration of NG-methyl-L-arginine (4.4 mg/kg, i.v.). In contrast, NG-methyl-L-arginine failed to reverse the hypotensive response to an equivalent depressor dose of nitroglycerin, a compound that acts by forming nitric oxide by a nonenzymatic, arginine-independent mechanism. The effect of NG-methyl-L-arginine on TNF-induced hypotension was antagonized, and the hypotension restored, by administration of excess L-arginine (100 mg/kg, i.v.). Our findings suggest that excessive nitric oxide production mediates the hypotensive effect of TNF.

Animals↗
PubMed1990

Localized leukemic pulmonary infiltrates. Diagnosis by bronchoscopy and resolution with therapy.

Although commonly found at autopsy, leukemic infiltration of the lung is rarely recognized as a cause of respiratory symptoms or roentgenographic densities. Previously reported cases of patients who had symptomatic or roentgenographic acute leukemic lung diseases invariably presented with diffuse pulmonary infiltrates. We describe three patients with leukemic involvement of the lung who presented with cough, fever, and localized roentgenographic infiltrates suggestive of bacterial pneumonia. In each case, the diagnosis was made by transbronchial biopsy specimen and confirmed by complete response to chemotherapy. In common with the other reported cases, all of our patients had peripheral blast counts above 40 percent (greater than 6,000 blasts per ml3) at the time the pulmonary diagnosis was made. Leukemic invasion of the lung should be considered in patients with acute leukemia who develop lung infiltrates--whether diffuse or focal--in association with a high peripheral blast count.

Adult↗