Recent Publications by CFE Educators

Discovery of the occurrence of neurokinin-1 (NK-1) receptor internalization in response to agonist activation has provided researchers with a new tool for studying tachykinin actions. Using the readily observable end point of NK-1 receptor internalization as an activity marker, this observation has allowed for more detailed study of tachykinin systems in vivo and in vitro. What has this technique taught us about tachykinin function and activity in the spinal cord? Here we discuss recent findings, which shed light on the functional relevance of receptor internalization, the regulation of neuropeptide release from primary afferent nociceptors, and the signaling produced by tachykinins during nociception and injury. The potential consequences of these discoveries for the treatment of pain and understanding of the role of tachykinins in nociception are discussed.

HYPOTHESIS

Cinematic technetium Tc 99m red blood cell ((99m)Tc-RBC) scans, in which real-time scanning is performed and analyzed, can accurately localize gastrointestinal bleeding and thus direct selective surgical intervention.

DESIGN

Retrospective medical record review with historical controls.

SETTING

Large, university-affiliated public hospital in urban setting.

PATIENTS

Twenty-six patients presenting with upper and lower gastrointestinal hemorrhage who underwent cinematic (99m)Tc-RBC scan examinations between 1990 and 1997 and required surgical intervention to control the bleeding.

INTERVENTIONS

All patients with gastrointestinal bleeding underwent open surgical procedures to provide cessation of bleeding and resection of appropriate abnormalities.

MAIN OUTCOME MEASURES

Patient outcome was based on correlation between preoperative RBC scans and intraoperative findings, surgical pathology, and postoperative clinical course.

RESULTS

Twenty-five (96%) of 26 scans were interpreted as positive for gastrointestinal bleeding. In 22 of these 25 scans, the site of bleeding was correctly identified for a sensitivity of 88%. One or more additional diagnostic tests were performed on 19 (73%) of 26 patients, and included angiography and flexible endoscopy. The most common operation performed to control bleeding was a hemicolectomy (14/26). Diverticulosis was the most prevalent diagnosis (46%). Two patients (8%) experienced rebleeding after operation. The overall mortality rate was 19% (5/26).

CONCLUSIONS

Cinematic (99m)Tc-RBC scintigraphy is a sensitive, noninvasive alternative to mesenteric angiography for accurately localizing the site of gastrointestinal hemorrhages. As such, this technique can be reliably used to direct selective surgical intervention.

Immunologic and virologic outcomes of treatment interruption were compared for 5 chronically human immunodeficiency virus (HIV)-infected persons who have maintained antiretroviral therapy-mediated virus suppression, as compared with 5 untreated controls. After a median interruption of 55 days of therapy accompanied by rebound of virus, reinitiated therapy in 4 of 5 subjects resulted in suppression of 98.86% of plasma virus load by 21-33 days and no significant decrease in CD4 T cell percentage from baseline. Increased T helper responses against HIV-1 p24 antigen (P=. 014) and interferon-gamma-secreting CD8 T cell responses against HIV-1 Env (P=.004) were present during interruption of therapy and after reinitiation of treatment. The remaining subject whose treatment was interrupted did not resume treatment and continued to have a low virus load (1080 HIV-1 RNA copies/mL) and persistent antiviral cell-mediated responses. In summary, cellular immunity against autologous HIV-1 has the potential to be acutely augmented in association with temporary treatment interruption in chronically infected persons.

Apolipoprotein L is a newly recognized component of human plasma lipoproteins. Mainly associated with apoA-I-containing lipoproteins, it is a marker of distinct HDL subpopulations. In an effort to gain inference as to its as yet unknown function, we studied biological determinants of apoL levels in human plasma. The distribution of apoL in normal subjects is asymmetric, with marked skewing toward higher values. No difference was found in apoL concentrations between males and females, but we observed an elevation of apoL in primary hypercholesterolemia (10.1 vs. 8.5 microgram/mL in control), in endogenous hypertriglyceridemia (13.8 microgram/mL, P 0.001), combined hyperlipidemia phenotype (18.7 g/mL, P 0.0001), and in patients with type II diabetes (16.2 microgram/mL, P 0.02) who were hyperlipidemic. Significant positive correlations were observed between apoL and the log of plasma triglycerides in normolipidemia (0.446, P 0.0001), endogenous hypertriglyceridemia (0.435, P 0.01), primary hypercholesterolemia (0.66, P 0.02), combined hyperlipidemia (0.396, P 0.04), hypo-alphalipoproteinemia (0.701, P 0.005), and type II diabetes with hyperlipidemia (0.602, P 0. 01). Apolipoprotein L levels were also correlated with total cholesterol in normolipidemia (0.257, P 0.004), endogenous hypertriglyceridemia (0.446, P = 0.001), and non-insulin-dependent diabetes mellitus (NIDDM) (0.548, P 0.02). No significant correlation was found between apoL and body mass index, age, sex, HDL-cholesterol or fasting glucose and glycohemoglobin levels. ApoL levels in plasma of patients with primary cholesteryl ester transfer protein deficiency significantly increased (7.1 +/- 0.5 vs. 5.47 +/- 0.27, P 0.006).

Helicobacter pylori possesses a homolog of the luxS gene, initially identified by its role in autoinducer production for the quorum-sensing system 2 in Vibrio harveyi. The genomes of several other species of bacteria, notably Escherichia coli, Salmonella enterica serovar Typhimurium, and Vibrio cholerae, also include luxS homologs. All of these bacteria have been shown to produce active autoinducers capable of stimulating the expression of the luciferase operon in V. harveyi. In this report, we demonstrate that H. pylori also synthesizes a functional autoinducer (AI-2) that can specifically activate signaling system 2 in V. harveyi. Maximal activity is produced during early log phase, and the activity is diminished when cells enter stationary phase. We show that AI-2 is not involved in modulating any of the known or putative virulence factors in H. pylori and that a luxS null mutant has a two-dimensional protein profile identical to that of its isogenic parent strain. We discuss the implications of having an AI-2-like quorum-sensing system in H. pylori and suggest possible roles that it may play in H. pylori infection.

OBJECTIVES

We sought to test the hypothesis that C-reactive protein, a marker of inflammation, would correlate positively with coronary calcium, a marker of atherosclerosis, in postmenopausal women.

BACKGROUND

High sensitivity testing for C-reactive protein (hsCRP) has recently been shown in large population studies to predict cardiac events in asymptomatic postmenopausal women. Coronary calcification determined by electron beam computerized tomography (EBCT) has also been suggested to be predictive of cardiac events in women.

METHODS

We performed hsCRP testing and determined calcium scores by EBCT in 172 asymptomatic postmenopausal women (mean age: 64.5 +/- 7.9 years) at risk for cardiac disease. Risk factors were determined by history, physical, electrocardiogram, exercise testing, and lipoprotein profiles.

RESULTS

Calcium scores ranged from 0 to 2,618. For analysis, calcium scores were divided into three groups; none (0 to 10), minimal (>10 to 50), and significant (>50). Overall, there was no significant positive relationship between hsCRP level and calcium score. Specifically, the hsCRP levels (mg/dl) were 0.24 +/- 0.43, 0.33 +/- 0.47 and 0.17 +/- 0.32 (medians 0.11, 0.15, and 0.06) for women with none, minimal, and significant coronary calcification, respectively. In subgroup analysis, a similar lack of positive association was observed after stratification by smoking status and by hormone replacement therapy use, two factors known to increase hsCRP.

CONCLUSIONS

In contrast to our a priori hypothesis, we found no evidence of a positive association between hsCRP and calcium score by EBCT. These data thus raise the possibility that hsCRP and EBCT calcium score reflect different pathologic processes, an issue with implications for coronary artery disease screening.

Cross-sectional studies by intravascular ultrasound (IVUS) in heart transplant recipients have suggested that vascular remodeling occurs in coronary arteries years after transplant. However, no reports describe vascular remodeling in the same cohort of patients studied prospectively using morphometric analysis (10 evenly spaced images obtained from a slow pullback from the left anterior descending coronary artery). Morphometric analysis better reflects total vessel anatomy compared with previously reported site (2 to 3 images) analysis. We reviewed 20 patients studied by IVUS at 2 months, 1 year, 2 years, and 3 years after heart transplant.Over time, the coronary artery luminal area decreased from baseline level of 12.0 mm(2) to a 3-year mark of 9.7 mm(2) (p = 0.02). Vessel shrinkage was seen in 16/20 patients. After an initial rise in intimal parameters (maximal intimal thickness, intimal index, and plaque area) from baseline to 1 year, we found a significant decrease in intimal parameters between Year 1 and Year 3 after transplant. For example, plaque area decreased from 2.05 mm(2) at 1 year post-transplant to 1.48 mm(2) by 3 years post-transplant (p = 0.05). In a majority of heart transplant patients, early intimal thickening in the first year post-transplant is accompanied by constrictive remodeling. Over the subsequent 2 years, further constrictive remodeling is seen despite a decrease in intimal area.

BACKGROUND

Cirrhosis is characterized by the accumulation of collagen within the extracellular matrix (ECM) of the liver and progressive hepatocellular dysfunction. Since recent studies have shown that the ECM can modulate cellular function, we examined whether the ECM could contribute to hepatocellular dysfunction. To address this question we examined hepatocyte behavior in two different ECM environments.

MATERIALS AND METHODS

Primary rat hepatocytes were cultured as a monolayer on collagen or as multicellular aggregates (spheroids) within a laminin-rich ECM. Hepatocytes were then compared for viability, response to proinflammatory cytokines, and their capacity to activate a heat shock response and adopt a thermotolerant phenotype. In addition, we compared the ability of prior heat shock exposure to protect hepatocytes from tumor necrosis factor (TNF) alpha/actinomycin-D-induced apoptosis in the two different ECM environments.

RESULTS

Hepatocytes cultured as a monolayer on collagen exhibited decreased viability, underwent spontaneous apoptosis, and displayed an attenuated cytokine-stimulated nitric oxide production compared to hepatocytes cultured as spheroids. In response to heat, hepatocytes in both ECM environments expressed inducible heat shock protein 70 (hsp72). But, only the hepatocyte spheroids exhibited thermotolerance in response to a subsequent thermal challenge. In contrast to previous reports, induction of the heat shock response failed to protect hepatocytes against TNFalpha-induced apoptosis.

CONCLUSIONS

These data demonstrate that the ECM can play an integral role in specific hepatocellular behaviors. Furthermore, the progressive deposition of collagen within the ECM, which is characteristic of fibrotic liver diseases, may directly contribute to the progressive hepatocellular dysfunction observed in cirrhosis. Hepatocellular viability, response to proinflammatory cytokines, heat shock response, and thermotolerance were all altered depending on the composition of the ECM. In contrast, TNFalpha-induced apoptosis was independent of the composition of the ECM.