Biomedical subjects
D R Nelson
Publications and source records attributed to D R Nelson.
Pathogenesis of chronic hepatitis C virus infection.
HCV-infected patients with chronic liver disease have evidence of circulating HCV-specific antibodies and a polyclonal, multi-specific T cell response. CD4+ proliferative responses and HCV-specific CTLs directed against one or more viral antigens are readily detected in those individuals who develop chronic HCV infection and appear to compartmentalize within the liver. Cytokines, which are produced locally within the liver and systemically, may play an important role in controlling viral replication and contributing to hepatocellular damage. However, neither the humoral nor cellular immune response, nor the cytokine response appears sufficient to eradicate infection in most patients. In its attempt to clear the virus from the liver, the immune system contributes to the hepatocellular injury seen in the majority of chronically infected patients. A better understanding of the host's immune response may provide further insight on the pathogenetic mechanisms involved in development of chronic hepatitis and aid the development of better therapeutic strategies.
Mutagenesis of some positive and negative residues occurring in repeat triad residues in the ADP/ATP carrier from yeast.
In AAC2 from Saccharomyces cerevisiae, nine additional charged residues (six positive, three negative) were neutralized by mutagenesis following the previous mutation of six arginines. Oxidative phosphorylation (OxPhos) in cells and mitochondria, the expression level of AAC protein, and the various transport modes of AAC in the reconstituted system were measured. Mutations are: within the first helix at K38A which is exclusive for AAC; K48A, and R152A, part of a positive triad occurring in the matrix portion of each repeat; two matrix lysines, K179M and K182I, and the negative triad helix-terminating residues, E45G, D149S, D249S. Cellular ATP synthesis (OxPhos) is nearly completely inhibited in K48A, R152A, D149S, and D249S, but still amounts to 10% in K38A and between 30% and 90% in the gly+ mutants K179M, K179I + K182I, and E45G. Comparison of the AAC content measured by ELISA and the binding of [3H]CAT and [3H]BKA reveals discrepancies in K48A, D149S, and D249S mitochondria, which provide evidence that these mutations largely abolish inhibitor binding. Also these mitochondria have undetectable OxPhos. Differently in K38A, CAT and BKA binding are retained at high AAC levels but OxPhos is very low. This reveals a special functional role of K38, different from the more structural role of R152, K48, D149, and D249. Transport activity was measured with reconstituted AAC. The electroneutral ADP/ADP exchange of gly- mutants is largely or fully suppressed in K48A, D149S, and D249S. K38A and R152A are still active at 18% and 30% of wt. The other three exchange modes, ATP/ADP, ADP/ATP, and ATP/ATP, are nearly suppressed in all gly- mutants but remain high in gly+ mutants. ATP-linked modes are higher than the ADP/ADP mode in gly+ but lower in gly- mutants, resulting in an exchange mode inversion (EMI). In the competition for AAC2 transport capacity, the weak ATP exporting modes are suppressed by the much stronger unproductive ADP/ADP mode causing inhibition of OxPhos. Together with previous results all members of three charge triads are now mutagenized, revealing drastic functional rotatory asymmetries within the three repeat domains. In the intrahelical arginine triad the third (R294A), in the positive matrix triad the second (R152A), and in the helix-terminating negative triad the first (E45G) still show high activity.
Endothelial activation and development of coronary artery disease in transplanted human hearts.
CONTEXT: The development of coronary artery disease in heart transplants is often associated with graft failure. Early detection of allografts prone to develop this disease is essential to institute new therapeutic approaches that could prolong allograft function. OBJECTIVE: To determine if early activation of arterial/arteriolar endothelium predicts the development of coronary artery disease, graft failure, or both in transplanted human hearts. DESIGN: Prospective cohort study. SETTING: Heart Transplant Center. PARTICIPANTS: A total of 121 consecutive adult cardiac allograft recipients who received transplants between 1988 and 1995 and were followed up through 1996. MAIN OUTCOME MEASURES: Development of coronary artery disease and graft failure. METHODS: Immunocytochemistry was performed on serial endomyocardial biopsy specimens to evaluate endothelial activation markers (intercellular adhesion molecule-1 and histocompatibility antigen HLA-DR) in arteries and arterioles. The presence and progression of coronary artery disease was evaluated by annual coronary angiograms with side-by-side comparisons. RESULTS: None of the 121 donor hearts showed arterial/arteriolar endothelial activation before transplantation. Arterial/arteriolar endothelial activation was present in 78 and absent in 43 of 121 allografts during the first 3 months after transplantation. The time of appearance and the proportion of biopsy specimens showing endothelial activation during these first 3 months were significantly associated with the risk of developing coronary artery disease, the progression of the disease, and the time required to develop the disease (P<.001). Significantly more patients with arterial/arteriolar endothelial activation died or received a second transplant (P<.001). CONCLUSIONS: Activation of arterial/arteriolar endothelium in transplanted human hearts predicts development of coronary artery disease and increased risk of graft failure.
Antibody to the host cellular gene-derived epitope GOR-1 in liver transplant recipients with hepatitis C virus infection.
The presence of anti-GOR was determined in paired pre-orthotopic liver transplantation (pre-OLT) and post-OLT sera from 87 OLT patients with hepatitis C virus infection. Before OLT, 48/87 patients were seropositive for anti-GOR, but this marker had no relationship with the clinical and biochemical parameters, or viremia level. Anti-GOR was less commonly detected in patients infected with genotype 3a, compared with genotypes 1 and 2, which might be related to the less conserved nature of the proposed shared epitope (amino acid sequence 9-18) in genotype 3a isolates. After OLT (median follow-up 16 months), anti-GOR was detected in 31/87 patients and it had no correlation with the clinical and biochemical parameters, viremia level, histologic disease activity, and clinical outcome. Changes in anti-GOR status (before OLT versus after OLT) were also not related to any of the clinical parameters. Although anti-GOR is commonly detected in OLT patients infected with hepatitis C virus genotypes 1 and 2, it has no clinical or prognostic significance.
Intussusception in cattle: 336 cases (1964-1993).
OBJECTIVE: To evaluate risk factors and to describe clinical and laboratory findings, surgical management, and postoperative outcome for cattle with intussusception. DESIGN: Hospital-based, case-control epidemiologic study and retrospective case series. SAMPLE POPULATION: Medical records of cattle admitted to 17 veterinary medical teaching hospitals in North America. PROCEDURE: Epidemiologic analysis of demographic data and detailed analysis of medical records for selected cattle. RESULTS: 336 cattle with intussusception were identified, 281 had small intestinal, 7 had ileocolic, 12 had cecocolic, and 36 had colocolic intussusceptions. Sex and season were not significantly associated with cattle developing intussusception, whereas calves < 2 months old were at greater risk of developing small intestinal intussusception than older cattle. Analysis of medical records of 57 cattle with intussusception revealed that these cattle were mildly hyponatremic, hypochloremic, hypocalcemic, azotemic, and hyperglycemic. Right flank laparotomy with a cow in a standing position, followed by intestinal resection and end-to-end anastomosis was the most common means of surgical correction. Overall survival rate (20/57; 35%) and postoperative survival rate (20/46; 43%) for cattle with intussusception were much lower than previously reported. CLINICAL IMPLICATIONS: Although rare in cattle, intussusception was most common in calves < 2 months old. Survival rate for cattle treated for intussusception was low (< 50%).
The role of hepatitis C virus-specific cytotoxic T lymphocytes in chronic hepatitis C.
Cellular immune responses, particularly those mediated by CD8+ CTL, may be important in the pathogenesis and control of hepatitis C virus (HCV) infection. To define the role of HCV-specific CTL in chronic hepatitis C, HCV-specific CTL activity in liver and peripheral blood was assessed in 35 patients with chronic HCV infection and 5 non-HCV controls. HCV-specific CTL activity of expanded CD8+ cells was evaluated against autologous lymphoblastoid cells transduced with recombinant vaccinia virus vectors expressing HCV genotype 1a Ags. CTL activity was detected in unprimed bulk-expanded CD8+ cells derived from the liver in 16 of the 35 patients, but not in peripheral circulation. Three patients infected with non-type 1 HCV were found to have HCV-specific CTL activity against HCV type 1a epitopes, all directed toward HCV core region. Compared with patients without detectable HCV-specific CTL activity based on our assay, those exhibiting CTL activity had lower levels of viremia (p < 0.01 for both branched DNA version 1.0 and 2.0 assays) and more active disease, as reflected by a higher histologic activity index (p = 0.006) and serum alanine aminotransferase levels (p = 0.03). It is concluded that 1) with nonspecific stimulation, HCV-specific CTL activity is found more commonly in the liver than in peripheral circulation, suggesting a tissue-specific localization with HCV-specific CTL and/or its precursors; 2) cross-genotype CTL activity exists, especially toward HCV core, which is relatively conserved across genotypes; and 3) patients with intrahepatic HCV-specific CTL activity had lower levels of viremia and more active liver disease.
Serum interleukin 4 and interleukin 10 levels in patients with chronic hepatitis C virus infection.
BACKGROUND/AIMS: Immune-mediated mechanisms are believed to play an important pathogenetic role in chronic hepatitis C virus infection. Interleukin 4 (IL-4) and IL-10 are secreted by T helper-2 type cells (Th2) which may downregulate cell-mediated immune effector mechanisms important in the host defense against intracellular pathogens. This study aimed to determine Th2 cytokine levels in chronic hepatitis C virus infection. METHODS: Serum IL-4 and IL-10 levels were measured in 74 patients with chronic hepatitis C virus infection and 20 healthy controls. The expression of CD30 in liver, a marker that is preferentially expressed in Th2 cells, was also determined by immunohistochemical staining in 37 patients. RESULTS: Serum IL-4 and IL-10 were below the detection limit (5 pg/ml) in all 20 healthy controls. However, 36 patients (49%) had elevated serum IL-4 levels (range 5-106 pg/ml, p<0.001) and 23 patients (31%) had elevated serum IL-10 levels (range 5-37 pg/ml, p<0.05). There was no correlation between serum IL-4 and IL-10 levels. There was also no correlation between serum IL-4 and IL-10 levels and any of the clinical (age, gender, mode of acquisition), biochemical (serum alanine transaminase levels), virologic (viremia level, genotype), and histological parameters examined. Twenty of 37 liver biopsy specimens from patients with chronic hepatitis C virus infection showed occasional CD30+ lymphocytes, suggestive of Th2 phenotype. However, in 20 of the 37 patients with paired cryostat liver sections, IL-4 was not detected in any of these patients, suggesting that IL-4 was not produced in the liver in patients with chronic hepatitis C virus infection. CONCLUSIONS: This study showed that serum Th2 cytokines are elevated (but at a low level) in a proportion of patients with chronic hepatitis C virus infection. However, the elevated Th2 cytokine levels may represent a systemic response and not a result of increased local production within the liver.
Radiographic detection of gravel in soft tissue.
STUDY OBJECTIVE: We sought to quantify the detectable size of varying compositions of gravel using a cadaveric chicken leg wound model and standard plain-film two-view radiographs. METHODS: We conducted a randomized, blinded, descriptive study with the assistance of faculty from the emergency medicine and radiology residency programs of a private urban teaching hospital. A standardized wound was created in each of 160 cadaver chicken legs. Zero, one, or two pieces of gravel of four differing compositions, ranging in size from .25 to 2.0 mm, were inserted into the wounds as determined with computer-generated randomization. The legs were then radiographically imaged (anteroposterior and lateral views). Three faculty physicians independently interpreted the radiographs to determine the number of foreign bodies and rated the ease of visibility. We calculated sensitivity, specificity, and interobserver reliability. RESULTS: The accuracy with which gravel was detected ranged from an average of 97.7% for 2-mm and 1-mm particles to less than 75% for .5-mm and .25-mm particles. Visibility ratings were also lower for particles in the smaller ranges. Sensitivity was greater for the emergency physicians than for the radiologists, but their specificity was lower. Salt-and-pepper gravel was the most easily identified foreign body. CONCLUSION: In this wound model, gravel particles of less than 1 mm were not accurately identified.
Dobutamine stress tele-echocardiography for evaluation of emergency department patients with chest pain.
OBJECTIVES: The practically and accuracy of dobutamine stress tele-echocardiography (DSTE) were assessed in patients presenting to the emergency department with chest pain. BACKGROUND: Many patients evaluated for chest pain in the emergency department (ED) are admitted to the hospital needlessly because of the difficulty in differentiating noncardiac chest pain from myocardial ischemia. METHODS: One hundred sixty-three patients with no evidence of myocardial infarction on initial blood studies or the electrocardiogram who were recommended for hospital admission to rule out myocardial infarction or myocardial ischemia were enrolled in this four-phase study. Rest echocardiography was performed in the ED, and the images were transmitted to a cardiologist for interpretation. If the results were normal, DSTE was then administered by a trained nurse. In the first three phases, all patients were admitted for observation regardless of the results of DSTE. In the fourth phase, those having normal DSTE results were able to be released. RESULTS: The test was completed within an average of 5.4 h of presentation to the ED. The sensitivity and specificity of DSTE versus clinical and cardiac catheterization findings were 89.5% and 88.9%, respectively, with a negative predictive value for DSTE of 98.5%. Patients experienced frequent mild side effects (54.7%), but few (6.3%) caused the test to be discontinued prematurely. In phase 4 of the study, 72% of those slated for hospital admission because of cardiac risk factors and chest pain suggesting myocardial ischemia were discharged after normal DSTE results. CONCLUSIONS: The use of DSTE in the evaluation of patients presenting with chest pain may improve screening for those who can be safely released from the ED.
Pathogenesis of hepatocellular damage in chronic hepatitis C virus infection.
Multiple factors may influence the host-virus interaction in patients infected with hepatitis C virus (HCV), and these may result in diverse disease presentations. In immune competent hosts, there is little evidence that direct cytopathicity plays a significant role in liver cell injury. However, when host conditions are altered to allow for unusually high levels of viral replication and viral protein expression (i.e., immunosuppression), HCV may induce direct hepatocellular damage. In most patients infected with HCV, a wide array of humoral and cell-mediated immune responses are triggered in response to HCV polypeptides; however, despite this host immune response, HCV infections usually persist. Furthermore, the host immune response, in its attempt to clear the virus from the liver, contributes to the hepatocellular damage (chronic hepatitis) seen in the majority of chronically infected patients.
Activation of tumor necrosis factor-alpha system in chronic hepatitis C virus infection.
Tumor necrosis factor-alpha (TNF-alpha) plays a central role in the host's immunomodulatory response to infective agents. To evaluate the TNF-alpha system in patients with chronic hepatitis C virus (HCV) infection, plasma, serum, and peripheral blood mononuclear cells (PBMC) were prospectively collected from 53 patients and 33 healthy control subjects. Circulating TNF-alpha and TNF receptors were assayed by their respective enzyme immunoassays. In addition, TNF-alpha mRNA was quantitated in PBMC using a branched DNA assay, and production of TNF-alpha by PBMC with and without lipopolysaccharide was also assessed. Patients with chronic HCV infection had a higher level of circulating TNF-alpha compared to healthy control subjects (9.62 +/- 6.01 vs 3.66 +/- 1.23 pg/ml, P < 0.001). They also had higher circulating levels of TNF receptors compared to control (CD120a: 3323 +/- 1267, pg/ml, N = 49 vs 1855 +/- 422 pg/ml, N = 33, P < 0.001; CD120b: 1290 +/- 650 pg/ml, N = 51, vs 863 +/- 207 pg/ml, N = 33, P < 0.001). Plasma TNF-alpha level correlated with circulating CD120a (r = 0.52, N = 49, P < 0.001) and weakly with CD120b (r = 0.32, N = 51, P = 0.02). Plasma TNF-alpha also correlated with markers of hepatocellular injury, including ALT (r = 0.34, N = 53, P = 0.01) and alpha-GST (r = 0.31, N = 43, P = 0.042), but not with serum HCV RNA levels. There was no difference in the TNF-alpha mRNA levels in PBMC between patients with chronic HCV infection (1.4 +/- 1.9 units/10[6] cells, N = 8) and healthy control subjects (2.1 +/- 1.4 units/10[6] cells, N = 8, P = NS). There was also no difference in the spontaneous production of TNF-alpha by PBMC (1 x 10[6] cells/ml) between patients with chronic HCV infection (14.2 +/- 36.5 pg/ml, N = 11) and healthy subjects (11.9 +/- 14.0 pg/ml, N = 14, P = NS). However, patients with chronic HCV infection produced more TNF-alpha upon stimulation with lipopolysaccharide compared to healthy control subjects (1278 +/- 693 pg/ml, N = 11, vs 629 +/- 689 pg/ml, N = 14, P < 0.05). These data indicate that the TNF-alpha system is activated in patients with chronic HCV infection.
Transforming growth factor-beta 1 in chronic hepatitis C.
Transforming growth factor-beta 1 (TGF-beta 1) has been implicated in mediating hepatic fibrogenesis and is known to have negative regulatory effects on the immune system. To analyse the effects of TGF-beta 1 in chronic HCV, serum samples were prospectively collected from 88 chronic hepatitis C virus (HCV) patients and 34 healthy controls. Total and biologically active TGF-beta 1, interleukin (IL)-4 and IL-10 were measured by enzyme-linked immunosorbent assay (ELISA). HCV RNA levels were quantified by branched DNA signal amplification pathway (bDNA), and HCV genotypes were determined by restriction fragment length polymorphism (RFLP) based on the 5'-untranslated region (UTR). Histological diagnosis was available in 87 patients, and liver sections from 80 other HCV patients were evaluated for hepatic expression of TGF-beta 1 using immunohistochemistry. Patients with chronic HCV infection had a higher level of TGF-beta 1, both total (817 +/- 464 ng ml-1) and biologically active forms (520 +/- 370 pg ml-1), compared with controls (total TGF-beta 1 183 +/- 105 ng ml-1, P < 0.001; active TGF-beta 1 290 +/- 140 pg ml-1, P < 0.01). There was no correlation between either total or biologically active TGF-beta 1 and clinical variables (age, gender, duration), liver biochemistry (serum alanine aminotransferase) or virological (HCV RNA level, genotype) parameters but there was a correlation between total TGF-beta 1 and Knodell scores (P = 0.03, n = 54). However, when individual histological parameters were analysed, only the fibrosis score showed significant correlation (P = 0.04, n = 54). Immunohistochemistry revealed that 62% of HCV patients had TGF-beta 1 present in sinusoidal cells. No correlation existed between hepatic expression of TGF-beta 1 and any histological parameters. A trend existed towards a correlation between total TGF-beta 1 and IL-4 (P = 0.059, n = 74) but not with IL-10. Therefore, the TGF-beta 1 system is activated in chronic HCV infection and may contribute towards hepatic fibrogenesis; in addition, the TGF-beta 1 system may interact with IL-4.
The quantitative effect of metoclopramide on abomasal and duodenal myoelectric activity of goats.
Electromyographic (EMG) recordings of the abomasal corpus, pyloric antrum and proximal duodenum were made from six goats for 2 h periods before and after administration of 0.5 mg/kg metoclopramide intravenously or intramuscularly. Analog EMG signal was transformed via a computer program to digital data. The percentage change in electrical activity was determined by comparing the electrical activity following administration of IV or IM metoclopramide with the electrical activity of the control periods for the abomasal corpus, pyloric antrum and proximal duodenum. Metoclopramide caused a significant, time-dependent increase in duodenal electrical activity following either route of administration. This increase in duodenal electrical activity coincided with peak plasma levels of metoclopramide until its decline below 100 ng/ml in plasma. There was a significant biphasic increase in electrical activity of the abomasal corpus and pyloric antrum following IM administration of metoclopramide. The first phase lasted approximately 5 min and was followed by a longer period (approximately 20 min) of diminished electrical activity. A second phase of increased electrical activity occurred approximately 40-60 min after initial IM injection of metoclopramide. It is uncertain whether this increase was drug-mediated or endogenously-triggered. Similar increases in corpus and antral electrical activity were present following IV metoclopramide administration, though early increases were not statistically significant. Overall, the percentage changes in electrical activity correlated well with predicted peak plasma levels of metoclopramide only in the duodenum. This correlation was limited to approximately 5 min after IV and 15 min after IM metoclopramide administration.
Comparison of routes of flumazenil administration to reverse midazolam-induced respiratory depression in a canine model.
OBJECTIVE: To determine whether flumazenil, a drug used to reverse benzodiazepine-induced respiratory depression and approved only for i.v. use, is effective by alternative routes. METHODS: A randomized, controlled, nonblinded, crossover canine trial was performed to evaluate reversal of midazolam-induced respiratory depression by flumazenil when administered by alternative routes. Mongrel dogs were sedated with thiopental 19 mg/kg i.v., then tracheally intubated. With the dogs spontaneously breathing, tidal volume, end-tidal CO2, and O2 saturation were observed until a stable baseline was achieved. Incremental doses of midazolam were administered until respiratory depression (30% decline in tidal volume, 10% decrease in O2 saturation, and 15% increase in end-tidal CO2) occurred. Flumazenil was administered by a randomly selected route [0.2 mg followed 1 minute later by 0.3 mg i.v., sublingual (s.l.) or intramuscular (i.m.); or 1 mg followed 1 minute later by 1.5 mg per rectum (PR)]. Time to return to baseline respiratory functions was recorded ("time to reversal"). Each of 10 dogs was studied using all 4 routes of flumazenil administration with a washout period of at least 7 days. An additional dog served as a control (no flumazenil). RESULTS: The control time to reversal was 1,620 seconds. The i.v. route was significantly faster (mean 120 +/- 24.5 sec) than the other 3 routes (p < 0.005). The SL route was the second fastest (mean 262 +/- 94.5 sec), the IM route was the third fastest (mean 310 +/- 133.7 sec) and the PR route was the s;owest (mean 342 +/- 84.4 sec). The SL, IM, and PR routes did not differ significantly from one another. CONCLUSIONS: Flumazenil administered by all 4 routes reversed midazolam-induced respiratory depression in a dog model. For the selected dosages used, the i.v. route was significantly faster than all 3 other routes, and SL was the second fastest.
Treatment of rupture of suspensory ligament and superficial flexor tendon in a bull.
Rupture of the suspensory ligament at the insertions on the proximal sesamoid bones, and of the superficial flexor tendon of the left fore limb, occurred in an adult Angus bull as a result of fighting. There was severe hyperextension of the metacarpophalangeal (MCP) joint with the dewclaws almost touching the ground. Radiographs revealed severe hyperextension of the MCP joint with the sesamoid bones aligned directly distal to the metacarpus. Initially, a full length fiberglass cast was applied with the limb partially flexed within the cast and the heels elevated. The cast was replaced twice. The cast was removed after 136 days and the bull was bearing full weight on the limb. Prolonged immobilisation of the limb produced new bone in the area (a normal response in cattle) to cause ankylosis of the traumatized MCP joint and partial ankylosis of the carpus. The bull was being used for pasture breeding one year after the injury.
Growth of Vibrio anguillarum in Salmon Intestinal Mucus.
The physiological changes of Vibrio anguillarum in response to growth in salmon intestinal mucus were investigated. Growth, survival, and changes in protein expression during growth in media supplemented with mucus were compared to growth and starvation in the identical media without mucus. V. anguillarum exhibited a rapid decline in CFU following growth in mucus as the sole carbon source. No such decline was observed in Luria broth with a 2% NaCl concentration, in glucose-minimal broth (3M), or during starvation in a carbon-, nitrogen-, and phosphorus-free salt solution (NSS). The changes in protein expression during growth in mucus were examined by labeling cells with [(sup35)S]methionine and analyzing the labeled proteins by one- and two-dimensional gel electrophoresis and autoradiography. Comparison of [(sup35)S]methionine-labeled proteins from mucus-grown cells with 3M-grown cells and NSS-starved cells revealed four de novo mucus-inducible proteins (Mips). These Mips were localized in the membrane fraction of V. anguillarum. Additionally, at least one other membrane protein was found to have increased expression in response to growth in mucus.
Treatment of chronic hepatitis C.
Explore the source record for details and available documents.