Reduced circulating FABP2 in patients with moderate to severe COVID-19 may indicate enterocyte functional change rather than cell death

The gut is of importance in the pathology of COVID-19 both as a route of infection, and gut dysfunction influencing the severity of disease. Systemic changes caused by SARS-CoV-2 gut infection include alterations in circulating levels of metabolites, nutrients and microbial products which alter immune and inflammatory responses. Circulating plasma markers for gut inflammation and damage such as zonulin, lipopolysaccharide and β-glycan increase in plasma along with severity of disease. However, Intestinal Fatty Acid Binding Protein / Fatty Acid Binding Protein 2 (I-FABP/FABP2), a widely used biomarker for gut cell death, has paradoxically been shown to be reduced in moderate to severe COVID-19. We also found this pattern in a pilot cohort of mild (n = 18) and moderately severe (n = 19) COVID-19 patients in Milan from March to June 2020. These patients were part of the first phase of COVID-19 in Europe and were therefore all unvaccinated. After exclusion of outliers, patients with more severe vs milder disease showed reduced FABP2 levels (median [IQR]) (124 [368] vs. 274 [558] pg/mL, P < 0.01). A reduction in NMR measured plasma relative lipid-CH3 levels approached significance (median [IQR]) (0.081 [0.011] vs. 0.073 [0.024], P = 0.06). Changes in circulating lipid levels are another feature commonly observed in severe COVID-19 and a weak positive correlation was observed in the more severe group between reduced FABP2 and reduced relative lipid-CH3 and lipid-CH2 levels. FABP2 is a key regulator of enterocyte lipid import, a process which is inhibited by gut SARS-CoV-2 infection. We propose that the reduced circulating FABP2 in moderate to severe COVID-19 is a marker of infected enterocyte functional change rather than gut damage, which could also contribute to the development of hypolipidemia in patients with more severe disease.

Osteopontin neutralisation abrogates the liver progenitor cell response and fibrogenesis in mice

BACKGROUND

Chronic liver injury triggers a progenitor cell repair response, and liver fibrosis occurs when repair becomes deregulated. Previously, we reported that reactivation of the hedgehog pathway promotes fibrogenic liver repair. Osteopontin (OPN) is a hedgehog-target, and a cytokine that is highly upregulated in fibrotic tissues, and regulates stem-cell fate. Thus, we hypothesised that OPN may modulate liver progenitor cell response, and thereby, modulate fibrotic outcomes. We further evaluated the impact of OPN-neutralisation on murine liver fibrosis.

METHODS

Liver progenitors (603B and bipotential mouse oval liver) were treated with OPN-neutralising aptamers in the presence or absence of transforming growth factor (TGF)-β, to determine if (and how) OPN modulates liver progenitor function. Effects of OPN-neutralisation (using OPN-aptamers or OPN-neutralising antibodies) on liver progenitor cell response and fibrogenesis were assessed in three models of liver fibrosis (carbon tetrachloride, methionine-choline deficient diet, 3,5,-diethoxycarbonyl-1,4-dihydrocollidine diet) by quantitative real time (qRT) PCR, Sirius-Red staining, hydroxyproline assay, and semiquantitative double-immunohistochemistry. Finally, OPN expression and liver progenitor response were corroborated in liver tissues obtained from patients with chronic liver disease.

RESULTS

OPN is overexpressed by liver progenitors in humans and mice. In cultured progenitors, OPN enhances viability and wound healing by modulating TGF-β signalling. In vivo, OPN-neutralisation attenuates the liver progenitor cell response, reverses epithelial-mesenchymal-transition in Sox9+ cells, and abrogates liver fibrogenesis.

CONCLUSIONS

OPN upregulation during liver injury is a conserved repair response, and influences liver progenitor cell function. OPN-neutralisation abrogates the liver progenitor cell response and fibrogenesis in mouse models of liver fibrosis.

Cytokine profiles in high risk injection drug users suggests innate as opposed to adaptive immunity in apparent resistance to hepatitis C virus infection

A cohort of injection drug users (IDU) have been identified who despite a long history of IDU and sharing of injecting equipment remain seronegative and aviraemic for hepatitis C virus (HCV). They have been termed HCV exposed uninfected (EU). The study of potential innate or adaptive immune mechanisms of resistance to HCV infection in this group is of interest. The aim of this study was to determine the levels of a broad range of cytokines in serum of exposed, uninfected individuals to ascertain whether there is a specific cytokine profile associated with apparent resistance to HCV. Sera from 22 EU individuals were analysed for a range of cytokines and chemokines, and compared to 16 treatment-naive chronic HCV cases (HCV Ab+ RNA+), 16 individuals with spontaneous resolution of HCV (HCV-Ab+ and HCV-RNA-) and 10 healthy unexposed controls. EU subjects had strikingly higher levels of both IL-6 (on average more than 100-fold, P = 0.001) and IL-8 (on average more than 10-fold, P < 0.001) than the comparison groups. Additionally higher levels of tumour necrosis factor-alpha (TNF-α; on average up to threefold, P = 0.02) were seen in EU individuals. The levels of interferon-alpha (IFN-α) were upregulated in all HCV exposed groups in comparison to healthy controls (P = 0.013). Adaptive immune cytokine levels were no different between the groups. Cytokine profiling demonstrated raised levels of pro-inflammatory innate immune cytokines and chemokines in EU IDU, in particular interleukin-6 and interleukin-8. These findings suggest innate immune activation may be the key to prevention of infection in this cohort.

P5-13-24: A Predictive Model of Early Systemic Disease Relapse after Standard Adjuvant Therapy for Breast Cancer

Background

Early relapse after adjuvant therapy for breast cancer is very discouraging and remains a major problem. We sought to identify predictors of early relapse risk and build a predictive model for relapse using prospectively collected data for patients seen at the Markey Cancer Center starting 2007 to date.

Methods: Of the 1098 new patients seen, 814 patients had stage I-III disease and were further analyzed for predictors of early relapse risk. Univariate analyses were performed for key variables including patient age, tumor size, grade, estrogen receptor (ER) status, progesterone receptor (PgR) status, and HER2 status. A multivariate Cox regression model was built to identify predictors of systemic relapse and model-building was performed using step-wise model selection to determine candidate models. A risk score was developed based on the linear combination of covariates in the final Cox model. Time-dependent predictive curves, a newly developed statistical methodology, were used to evaluate the predictive accuracy of the proposed risk score.

Results: Median patient age was 57 years (Range 25–92) and 88% were white. Forty six (46) % had stage I disease, 36% stage II, and 18% stage III. Median follow up time was 2.3 years. Of this 814 patient cohort, 708 patients had complete baseline covariate data and were used to build the candidate models. The final Cox regression model included 5 covariates that were significantly associated with risk of early relapse: stage III disease (p = 0.0011), grade III (p = 0.0028), PgR-negative status (p = 0.0121), HER2−negative status (p = 0.0305), and node-positive status (p = 0.0360). These five covariates were then used to calculate an early recurrence risk score, which is the weighted average of these risk factors when present, with the weights being the coefficients from the Cox regression model. The 1-year, 2-year and 3-year predictive curves for this risk score decrease considerably, especially for the 2-year and 3-year curves, indicating good predictive accuracy of the risk score. The highest risk score group, which represents 4.8% of the population, has a 1-year, 2-year and 3-year relapse probabilities of 13.0% (95% CI: 4.1%, 27.3%), 39.4 % (95% CI: 20.1%, 58.3%), and 52.3% (95% CI: 28.5%, 71.5%), respectively. In comparison, for the overall population, the corresponding 1-year, 2-year, and 3-year relapse probabilities were only 1.1% (95% CI: 0.5%, 2.1%), 4.2% (95% CI: 2.7%, 6.1%) and 6.2% (95% CI: 4.2%, 8.6%), respectively.

Conclusions: The developed risk score based on stage, tumor grade, PgR, HER2, and node status is highly predictive of early relapse in breast cancer patients after standard adjuvant therapy. Our model can be used to identify patients with high risk of early disease relapse who may otherwise benefit from enrollment on novel adjuvant therapeutic trials to improve their outcome.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-13-24.

Comparison of low-temperature-sensitive liposome encapsulated docetaxel and doxorubicin in a murine model of prostate cancer

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Background: Low-temperature-sensitive liposomes (LTSLs) release their encapsulated drug into targeted tissue when activated by a source of hyperthermia. The efficacy of an LTSL formulation of docetaxel (DOC) or doxorubicin (DOX) was compared against prostate cancer in a xenograft mouse model.

Methods: Under an approved IACUC protocol, Luciferase transfected human prostate PC-3M-luciferase cells were inoculated (3x106 cells) subcutaneously in the right hind leg of 8 wk old female athymic nude mice. When tumors reached a volume of 200–300 mm3, mice were randomized to receive one intravenous injection of saline, Stealth liposomal DOX (5 mg/kg), LTSL DOX (5 mg/kg), or LTSL DOC (15 mg/kg), with or without hyperthermia treatment (LTSL DOX and LTSL DOC were supplied by Celsion Corp., Columbia MD). Mice undergoing hyperthermia treatment were anesthetized and stabilized in a holder that allowed for only the leg with tumor to be heated to 41–42°C that triggered LTSL drug release. Mice were monitored daily for tumor volume and body weight. Study end-points included growth of tumor to 5x the initial treatment volume or monitoring of survival for 60 days.

Results: The LTSL DOC delayed tumor growth longer (> 14 days) than DOX (0 day) and LTSL DOX (1 day) with hyperthermia (P<0.05). Mice treated with LTSL DOC and hyperthermia survived longest (60 days) compared to all other mice (range 6–8 days, P<0.05). LTSL in the setting of hyperthermia demonstrated complete regression of tumor in 57% of mice.

Conclusions: LTSL DOC with hyperthermia delayed tumor growth more than all other treatments. Survival studies suggest LTSL DOC is a more effective temperature sensitive delivery system against PC-3M prostate tumors.

No significant financial relationships to disclose.

Hepatitis C virus-specific T-cell reactivity during interferon and ribavirin treatment in chronic hepatitis C

BACKGROUND & AIMS

The role of virus-specific T-helper lymphocyte reactivity in determining the therapeutic response in chronic hepatitis C virus (HCV) infection is not fully understood.

METHODS

We studied CD4(+) T lymphocyte proliferation together with interferon (IFN)-gamma and interleukin (IL)-10 production from peripheral blood mononuclear cells in response to 4 HCV antigens (core, NS3, NS4, and NS5) in 25 patients with chronic hepatitis C undergoing antiviral therapy with IFN alone or in combination with ribavirin, prospectively, before, during, and after treatment.

RESULTS

HCV-specific T-cell reactivity was uncommon at baseline but increased markedly during antiviral therapy, peaking around treatment weeks 4-8. Resolution of hepatitis C viremia was significantly more likely in patients who developed HCV-specific T-cell proliferation with increased IFN-gamma production. The main difference in T-cell reactivity of patients treated with IFN plus ribavirin was a significantly lower production of IL-10, whereas lymphocyte proliferation was similar to that in patients receiving IFN monotherapy.

CONCLUSIONS

Treatment-induced control of hepatitis C viremia is associated with the development of HCV-specific T-cell responses with enhanced IFN-gamma and low IL-10 production. The greater efficacy of combination therapy with IFN-alpha plus ribavirin may be related to its ability to suppress HCV-specific IL-10 production.

Hepatitis C virus (HCV) specific immune responses in anti-HCV positive patients without hepatitis C viraemia

BACKGROUND/AIMS

Most patients infected with hepatitis C virus (HCV) develop chronic infection and persistent viraemia. The immune mechanisms responsible for resolution of viraemia remain poorly understood. HCV specific humoral and cellular immune responses in patients with and without viraemia were investigated.

METHODS

In vitro T helper (TH) lymphocyte responses to structural and non-structural HCV proteins were determined by means of proliferative response and cytokine production in 35 anti-HCV positive/HCV RNA negative patients and in 31 patients with chronic HCV infection and persistent viraemia. Humoral responses were determined by measuring HCV specific antibody quantity and specificity.

RESULTS

A TH response to two or more HCV proteins was present in 18 of 35 patients with serological viral clearance compared with just one of 31 viraemic patients (p = 0.00001). HCV specific interferon-gamma production was increased only in the former group. In contrast, the antibody levels were significantly lower and directed at fewer HCV antigens in patients with undetectable HCV RNA.

CONCLUSIONS

Patients without viraemia after HCV infection frequently have strong TH lymphocyte responses of the TH1 type to multiple HCV antigens many years after the onset of infection, whereas antibody responses are less marked. These results suggest that control of HCV replication may depend on effective TH lymphocyte activation.

Hepatitis GB virus-C/hepatitis G virus infection in liver disease

Hepatitis GB virus-C (HGBV-C)/hepatitis G virus (HGV) infection was investigated in 106 children with liver disease (54 boys and 52 girls, mean age 7.3 years); 12 with chronic hepatitis C virus infection, 29 with positive hepatitis B surface antigen, nine with idiopathic fulminant hepatic failure, seven with graft dysfunction after liver transplantation associated with autoimmune features, 20 with cryptogenic liver disease, and 29 with autoimmune liver disease. HGV RNA detected by reverse transcription polymerase chain reaction was found to be positive in 4/106 patients (3.8%). Risk factors were identified in three patients, including blood transfusion and/or medical treatment in Eastern Europe. The prevalence was higher than that of blood donors but lower than that of 2 adult patients with liver disease. HGV is not associated with any specific disease group and does not seem to be a major aetiological agent of liver disease in childhood in the UK.

Hepatitis C virus infection in the development of hepatocellular carcinoma in cirrhosis

BACKGROUND/AIMS

The role of hepatitis C virus replication and different genotypes in the progression of cirrhosis to hepatocellular carcinoma is examined on the basis of a prospective follow-up of 1438 patients with histologically proven cirrhosis.

METHODS

The presence of HCV RNA, anti-HCV and characterisation of virus genotypes were determined in 72 cases who developed hepatocellular carcinoma after a median follow-up of 5.3 years (range 1 to 16) and compared to 72 controls who had cirrhosis only, after a median follow-up of 4.8 years (range 1 to 16). Patients in the hepatocellular carcinoma group and controls were matched, one to one, for age, sex, nationality, HBsAg seropositivity, duration of follow-up and aetiology of cirrhosis.

RESULTS

HCV RNA was detected in 31 of 72 (44%) patients who developed hepatocellular carcinoma, significantly more frequently than in 17 of 72 (23%) controls with cirrhosis (odds ratio 2.4, 95% confidence interval 1.2 to 5.0; p = 0.013). When cirrhosis of different aetiologies was analysed, hepatitis C virus replication was more frequently detected in patients developing hepatocellular carcinoma in association with cryptogenic cirrhosis (p = 0.007), alcoholic cirrhosis (p = 0.043) and hepatitis B virus seronegative cirrhosis (p = 0.05). Hepatitis C virus genotypes 1b and 4 were the most prevalent; they were found in 53% and 25%, respectively, of the patients studied, but were equally distributed between cirrhosis progressing to hepatocellular carcinoma and controls.

CONCLUSIONS

Persistent hepatitis C virus replication is closely associated with hepatocellular carcinoma development in cirrhosis, and there is no preferential role of individual hepatitis C virus genotypes.

Induction of T-helper cell response to hepatitis B core antigen in chronic hepatitis B: a major factor in activation of the host immune response to the hepatitis B virus

The T helper (Th) cell response to hepatitis B core antigen (HBcAg) was analyzed in 76 chronic hepatitis B virus (HBV) carriers with varying degrees of hepatic inflammation and HBV replication. Fifty-five patients had active viral replication, 28 with minimal histological changes and normal alanine transaminase (ALT) and 27 with active hepatic inflammation and elevated ALT. The remaining 21 chronic hepatitis B surface antigen (HBsAg) carriers had undetectable HBV replication, minimal histological activity, and normal ALT. In addition, 34 chronic HBV carriers were studied prospectively during treatment with alpha-interferon. The HBcAg-specific Th cell response was evaluated by a proliferative assay using 3H-thymidine uptake and gamma-interferon production by peripheral blood mononuclear cells. The proliferative response and gamma-interferon production of patients with active hepatic inflammation were significantly higher than in patients with minimal histological changes and in controls. In the longitudinal analysis during alpha-interferon treatment, 22 of 34 patients sustained an ALT flare accompanied by a parallel, significant Th cell response, which preceded or coincided with the ALT flare. The elevation in the Th cell response and the ALT flare were followed by a significant rise in the serum immunoglobulin (Ig) M anti-HBc index. Ten of twenty-two patients with an enhanced Th cell response and an ALT flare seroconverted after alpha-interferon treatment. The Th cell activity in the 10 responders rapidly subsided after hepatitis B e antigen (HBeAg) to anti-HBe seroconversion, whereas in the 12 nonresponders it remained elevated.(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of T-helper cell response to hepatitis B core antigen in chronic hepatitis B: a major factor in activation of the host immune response to the hepatitis B virus

The T helper (Th) cell response to hepatitis B core antigen (HBcAg) was analyzed in 76 chronic hepatitis B virus (HBV) carriers with varying degrees of hepatic inflammation and HBV replication. Fifty-five patients had active viral replication, 28 with minimal histological changes and normal alanine transaminase (ALT) and 27 with active hepatic inflammation and elevated ALT. The remaining 21 chronic hepatitis B surface antigen (HBsAg) carriers had undetectable HBV replication, minimal histological activity, and normal ALT. In addition, 34 chronic HBV carriers were studied prospectively during treatment with alpha-interferon. The HBcAg-specific Th cell response was evaluated by a proliferative assay using 3H-thymidine uptake and gamma-interferon production by peripheral blood mononuclear cells. The proliferative response and gamma-interferon production of patients with active hepatic inflammation were significantly higher than in patients with minimal histological changes and in controls. In the longitudinal analysis during alpha-interferon treatment, 22 of 34 patients sustained an ALT flare accompanied by a parallel, significant Th cell response, which preceded or coincided with the ALT flare. The elevation in the Th cell response and the ALT flare were followed by a significant rise in the serum immunoglobulin (Ig) M anti-HBc index. Ten of twenty-two patients with an enhanced Th cell response and an ALT flare seroconverted after alpha-interferon treatment. The Th cell activity in the 10 responders rapidly subsided after hepatitis B e antigen (HBeAg) to anti-HBe seroconversion, whereas in the 12 nonresponders it remained elevated.(ABSTRACT TRUNCATED AT 250 WORDS)

Genomic variations in the hepatitis B core gene: a possible factor influencing response to interferon alfa treatment

BACKGROUND/AIMS

Interferon treatment causes a sustained loss of virus replication only in a proportion of patients with chronic hepatitis B. This study investigated whether genomic variations in the precore/core gene of hepatitis B virus affect the response to interferon alfa.

METHODS

The precore/core region was sequenced in 46 serum samples obtained before, during, and after interferon treatment of 12 patients.

RESULTS

In 23 samples from 7 responders (group A), there were 24 missense mutations, whereas in 23 samples from 5 patients who did not respond or relapsed after treatment (group B), there were 141 missense mutations (P < 0.001). All group B patients had cirrhosis, but only 2 of 7 patients in group A had cirrhosis (P = 0.026). Substitutions in amino acids 21-27 of the core protein, known to diminish HLA-A2-restricted cytotoxic T-cell function, were found in all nonresponders but in none of the responders. No significant changes occurred in the precore/core region in responders after seroconversion to antibody to hepatitis B e antigen, but multiple variations persisted in group B during treatment and new mutations appeared with the relapse of hepatitis.

CONCLUSIONS

Specific mutations in the core protein that can interfere with T-cell function occur frequently in patients with advanced chronic hepatitis B and may affect the response to interferon.

Excimer laser-induced vasoreactivity

Earlier generations of excimer lasers, designed for industrial or non-cardiovascular medical applications, have been previously shown consistently to induce vasorelaxation of vascular smooth muscle in vitro. Such lasers were typically characterized by pulse durations of < or = 15 nanoseconds (ns). Excimer lasers currently employed for cardiovascular applications were designed with longer pulse durations (up to 220 ns) to facilitate fibreoptic transmission. Because arterial spasm has been observed in patients undergoing percutaneous revascularization with such lasers, we investigated the effect of so-called 'stretched pulse' excimer laser irradiation on vasomotor reactivity. A total of 69 rings of aorta harvested from New Zealand white rabbits were mounted isometrically in Krebs buffer solution and exposed to 308 nm from an excimer laser with a pulse duration of 120 ns. Fifty rings were exposed without pharmacological pre-treatment. The remaining 19 rings were exposed after pharmacological pre-treatment: 11 were precontracted with norepinephrine (NE, 10(-9)-10(-5) M), while eight were irradiated in Ca(2+)-free buffer after pre-relaxation with nitroglycerin (NTG, 7 x 10(-5) M). Without pharmacological pre-treatment, the vasomotor response to the excimer laser was variable: vasoconstriction was observed in 27 rings (16.1 +/- 0.8% (mean +/- SEM) of response to 5-HT), vasorelaxation in 21 rings (43.2 +/- 17.0% of response to 5-HT), and a heterogeneous response (vasoconstriction 4.9 +/- 1.0%, vasorelaxation 12.9 +/- 0.3%) in two rings. The vector of vasomotor response in non-precontracted rings was not predicted by fluence, frequency or temperature rise. A consistent vasomotor response was recorded only when pharmacological pre-treatment was employed. Among 11 rings pre-contracted with NE, the excimer laser produced vasorelaxation in 34/34 (100%) exposures; in contrast, among eight rings pre-relaxed with NTG in Ca(2+)-free buffer, the excimer laser produced vasoconstriction in 40/40 (100%) exposures. For all rings, including pre-contracted, pre-relaxed and those which were not pharmacologically pre-treated, the vector of vasomotor response was endothelium-independent. The magnitude of all vasomotor responses, including vasoconstriction in non-precontracted rings, could be diminished by limiting the duration of exposure. Thus, in contrast to the earlier generation, short-pulse excimer lasers, long pulse-duration excimer lasers in current clinical trials produce an unpredictable, heterogeneous vasomotor response. This in-vitro finding is consistent with the unpredictable development of vascular spasm in patients undergoing excimer laser angioplasty. Furthermore, these findings support the concept of employing abridged pulse trains to diminish the likelihood of laser-induced vasoconstriction during excimer laser angioplasty.(ABSTRACT TRUNCATED AT 400 WORDS)

In vitro evidence that myocardial ischemia resulting from 5-fluorouracil chemotherapy is due to protein kinase C-mediated vasoconstriction of vascular smooth muscle

5-Fluorouracil (5-FU) is a commonly employed chemotherapeutic agent. Among the various toxicities associated with 5-FU, cardiovascular toxicity, consisting principally of acute myocardial ischemia and/or myocardial infarction, has been reported in up to 8.5% of patients treated with this drug. While 5-FU-induced coronary vasospasm has been considered as a potential basis for such clinical toxicity, this hypothesis remains unsubstantiated by laboratory investigation. Accordingly, the present study was designed to investigate the hypothesis that 5-FU induces reversible vasoconstriction of vascular smooth muscle and to study the cellular mechanisms of such vasomotor alterations. To investigate the effects of 5-FU on the vasoreactivity of vascular smooth muscle, 479 exposures were performed in 105 rings of aorta freshly isolated from 23 New Zealand white rabbits. Vasoconstriction was documented in 20 of 86 (23%) rings exposed to 5-FU at 7 x 10(-5) M, 45 of 83 (54%) rings exposed to 5-FU at 7 x 10(-4) M, and 41 of 49 (84%) rings exposed to 5-FU at 7 x 10(-3) M. In each case, 5-FU-induced vasoconstriction was endothelium independent. Pretreatment of rings with 10(-9) M staurosporine, a protein kinase C (PK-C) inhibitor, reduced 5-FU-induced vasoconstriction from 25.0 +/- 6.5 to 2.5 +/- 1.7 mg; staurosporine at a concentration of 10(-8) M abolished 5-FU-induced vasoconstriction. Pretreatment of rings with 10(-7) M phorbol-12,13-dibutyrate, an activator of PK-C, increased the magnitude of 5-FU-induced vasoconstriction 23-fold, from 49.7 +/- 11.1 mg before to 1163.6 +/- 276.4 mg after phorbol-12,13-dibutyrate (P = 0.0002). Neomycin, an inhibitor of phosphoinositide turnover, did not alter the magnitude of 5-FU-induced vasoconstriction. Membrane receptor blockers, including the alpha-adrenergic receptor blocker phentolamine, the beta-adrenergic receptor blocker propranolol, the H1 receptor inhibitor diphenhydramine, the H2 receptor inhibitor cimetidine, the Ca2+ channel blockers verapamil and diltiazem, and the cyclooxygenase inhibitor indomethacin all failed to alter the magnitude of 5-FU-induced vasoconstriction. Furthermore, the 5-FU-related compounds uracil and floxuridine did not produce vasoconstriction. Finally, 5-FU-induced vasoconstriction was abolished by nitroglycerin. These results indicate that (a) 5-FU causes direct, endothelium-independent vasoconstriction of vascular smooth muscle in vitro, (b) this vasomotor response involves activation of PK-C, and (c) this response is independent of vasoactive cell membrane receptors, phosphoinositide turnover, or activation of the cyclooxygenase pathway.(ABSTRACT TRUNCATED AT 400 WORDS)

A new balloon-expandable tantalum coil stent: angiographic patency and histologic findings in an atherogenic swine model

The angiographic patency and histologic characteristics of a new balloon-expandable tantalum stent were studied after implantation intervals ranging from 1 to 32 weeks in atherogenic miniature swine peripheral and coronary arteries. Stents were placed in 34 arteries (10 coronary and 24 iliac arteries) in a total of 13 swine. Two swine died within 24 h of stent implantation. Follow-up angiography was performed before death was induced in 11 swine (8 coronary and 19 iliac arteries) and revealed 100% patency without evidence of lumen stenosis, thrombosis or migration of the stents. The neointimal thickening was maximal at 4 weeks after stent implantation and was at its minimum at 32 weeks after implantation with reendothelialization of the stents generally complete at that time. An advantage of this balloon-expandable device is its inherent longitudinal flexibility. The coil configuration allowed the nondeployed stent to negotiate acute bends in coronary arteries to reach the site of implantation and also allowed the deployed stent to conform to the natural contour of tortuous coronary arteries. The tantalum device was remarkable for its radiographic visibility, which greatly aided its placement under fluoroscopic guidance. This study demonstrates this stent's ease of implantation, excellent patency rate and absence of restenosis due to neointimal proliferation for up to 8 months in this atherogenic swine model.