Role of Vitamin E for Nonalcoholic Steatohepatitis in Patients With Type 2 Diabetes: A Randomized Controlled Trial

OBJECTIVE

While vitamin E has shown to improve nonalcoholic steatohepatitis (NASH) in patients without diabetes, information on patients with type 2 diabetes mellitus (T2DM) is lacking. The aim of this study was to determine whether vitamin E, alone or combined with pioglitazone, improves histology in patients with T2DM and NASH.

RESEARCH DESIGN AND METHODS

This was a proof-of-concept, randomized, double-blind, placebo-controlled trial conducted from 2010 to 2016. Patients with T2DM and biopsy-proven NASH (n = 105) were randomized to vitamin E 400 IU b.i.d., vitamin E 400 IU b.i.d. plus pioglitazone 45 mg/day, or placebo. Eighty-six patients completed the 18-month study. The primary end point was a two-point reduction in the nonalcoholic fatty liver disease activity score from two different parameters, without worsening of fibrosis. Secondary outcomes were resolution of NASH without worsening of fibrosis, individual histological scores, and metabolic parameters.

RESULTS

More patients on combination therapy achieved the primary outcome versus placebo (54% vs. 19%, P = 0.003) but not with vitamin E alone (31% vs. 19%, P = 0.26). Both groups showed improvements in resolution of NASH compared with placebo (combination group: 43% vs. 12%, P = 0.005; vitamin E alone: 33% vs. 12%, P = 0.04). While steatosis assessed by histology improved with combination therapy (P < 0.001) and vitamin E alone (P = 0.018), inflammation (P = 0.018) and ballooning (P = 0.022) only improved with combination therapy. No improvement in fibrosis was observed in any group.

CONCLUSIONS

In this proof-of-concept study, combination therapy was better than placebo in improving liver histology in patients with NASH and T2DM. Vitamin E alone did not significantly change the primary histological outcome.

Response to Pioglitazone in Patients With Nonalcoholic Steatohepatitis With vs Without Type 2 Diabetes

BACKGROUND & AIMS

Pioglitazone is effective for long-term treatment of patients with nonalcoholic steatohepatitis (NASH) with prediabetes or type 2 diabetes. However, it is not clear how the presence of type 2 diabetes affects the drug's efficacy. We compared metabolic and histologic responses to pioglitazone in patients with NASH and prediabetes vs type 2 diabetes.

METHODS

We performed a prospective study of adults with biopsy-proven NASH (52 with type 2 diabetes and 49 with prediabetes), enrolled from the general population of San Antonio, Texas, from 2008 through 2014. After a run-in period of approximately 4 weeks, when all baseline measurements were made (liver magnetic resonance proton spectroscopy, euglycemic insulin clamp with glucose turnover measurements, dual-energy absorptiometry, and liver biopsy), subjects were randomly assigned to groups given pioglitazone or placebo (45 mg/d) for 18 months; all procedures performed at baseline were then repeated. The primary outcome was a reduction in nonalcoholic fatty liver disease activity score of 2 points or more (for at least 2 components) without worsening of fibrosis (and expressed as difference vs placebo). Secondary outcomes included NASH resolution, individual histologic components, intrahepatic triglyceride content (measured by ¹H magnetic resonance spectroscopy), and insulin sensitivity (measured by euglycemic insulin clamp).

RESULTS

The primary outcome was met by 48% of patients with type 2 diabetes vs 46% without diabetes. Resolution of NASH was achieved in 44% of patients with type 2 diabetes vs 26% without diabetes. A significant reduction in fibrosis, from baseline, was observed only in patients with type 2 diabetes (P = .035). Intrahepatic triglyceride content was reduced by 11% ± 2% in patients with diabetes vs a reduction of 9% ± 2% in patients without diabetes (P = .62); the plasma level of alanine aminotransferase was reduced by 50 ± 10 U/L in patients with diabetes vs a reduction of 36 ± 5 U/L in patients without diabetes (P = .22). Pioglitazone was associated with a significantly greater insulin sensitivity in adipose tissue of patients with diabetes vs without diabetes (P < .001), but nonsignificant differences in responses in hepatic (P = .49) and skeletal muscle (P = .32) insulin sensitivity.

CONCLUSIONS

In a prospective study, we found pioglitazone to be effective in patients with and without type 2 diabetes. However, pioglitazone reduced liver fibrosis and increased adipose tissue insulin sensitivity at significantly greater levels in patients with type 2 diabetes than in patients with prediabetes. Further studies are needed to determine the mechanisms by which pioglitazone reduces liver disease in patients with type 2 diabetes. ClinicalTrials.gov: NCT00994682.

Liver Safety of Statins in Prediabetes or T2DM and Nonalcoholic Steatohepatitis: Post Hoc Analysis of a Randomized Trial

CONTEXT

Patients with nonalcoholic fatty liver disease have a high cardiovascular risk, but statins are rarely prescribed because of fear of hepatotoxicity.

OBJECTIVE

To prospectively assess the long-term safety of statins in patients with prediabetes/type 2 diabetes mellitus (T2DM) and nonalcoholic steatohepatitis (NASH).

DESIGN

Post hoc analysis of statin use during a randomized, controlled trial assessing pioglitazone vs placebo for NASH.

PATIENTS

A total of 101 patients (86 receiving statins) with biopsy-proven NASH and prediabetes/T2DM were followed for up to 36 months.

INTERVENTIONS

Oral glucose tolerance test and percutaneous liver biopsy (baseline, month 18, and month 36); liver magnetic resonance spectroscopy and euglycemic insulin clamp (baseline and month 18).

MAIN OUTCOME MEASURES

Histologic and biochemical safety of statin use among patients with NASH.

RESULTS

Only 37% of patients were receiving statins at enrollment despite their high cardiovascular risk. Statin nonusers had higher plasma alanine aminotransferase levels but similar histologic severity of liver disease at baseline. In both statin users and nonusers, the same number of patients (n = 4) had a twofold or greater increase in plasma aminotransferases during follow-up. One statin nonuser was discontinued from the study because of this elevation. Values returned to normal without any active measure in all other cases. No changes on liver histology or hepatic insulin resistance were observed in patients with NASH newly started on a statin and receiving placebo during the main study.

CONCLUSIONS

Statin therapy is safe in patients with prediabetes/T2DM and NASH. Given their high cardiovascular risk, statin therapy should be encouraged in this population.

Primary atypical teratoid rhabdoid tumor in the adult spine

Background:

Atypical teratoid/rhabdoid tumor (ATRT) is a highly aggressive tumor of the central nervous system (WHO grade IV), which is most frequently found intracranially in young children and infants. Only three prior cases of primary ATRT involving the adult spine were found following a literature review, and the average survival for these patients was only 20 postoperative months.

Case Description:

A 43 year-old female presented with an acute exacerbation of chronic neck pain. While awaiting magnetic resonance (MR) studies of the cervical spine, she was found pulseless in her room. Although cardiopulmonary resuscitation was successful, she was found to be quadriplegic. The subsequent cervical MR imaging revealed a C1-3 intradural, extramedullary ventrolateral mass, markedly compressing the upper cervical spinal cord. Following successful surgical resection of the lesion, which proved pathologically to be an ATRT, she was treated with a full course of fractionated radiation therapy. Over the successive 6-month period, her neurological examination continued to improve to 4-/5 functional strength in her upper extremities, however, remained with 2/5 nonfunctional strength in her legs.

Conclusions:

ATRT involving the adult spine are rare and may often be misdiagnosed. This study points out that aggressive surgery followed by radiation therapy may improve outcome.

Long-Term Pioglitazone Treatment for Patients With Nonalcoholic Steatohepatitis and Prediabetes or Type 2 Diabetes Mellitus: A Randomized Trial

BACKGROUND

The metabolic defects of nonalcoholic steatohepatitis (NASH) and prediabetes or type 2 diabetes mellitus (T2DM) seem to be specifically targeted by pioglitazone. However, information about its long-term use in this population is limited.

OBJECTIVE

To determine the efficacy and safety of long-term pioglitazone treatment in patients with NASH and prediabetes or T2DM.

DESIGN

Randomized, double-blind, placebo-controlled trial. (ClinicalTrials.gov: NCT00994682).

SETTING

University hospital.

PARTICIPANTS

Patients (n = 101) with prediabetes or T2DM and biopsy-proven NASH were recruited from the general population and outpatient clinics.

INTERVENTION

All patients were prescribed a hypocaloric diet (500-kcal/d deficit from weight-maintaining caloric intake) and then randomly assigned to pioglitazone, 45 mg/d, or placebo for 18 months, followed by an 18-month open-label phase with pioglitazone treatment.

MEASUREMENTS

The primary outcome was a reduction of at least 2 points in the nonalcoholic fatty liver disease activity score in 2 histologic categories without worsening of fibrosis. Secondary outcomes included other histologic outcomes, hepatic triglyceride content measured by magnetic resonance and proton spectroscopy, and metabolic parameters.

RESULTS

Among patients randomly assigned to pioglitazone, 58% achieved the primary outcome (treatment difference, 41 percentage points [95% CI, 23 to 59 percentage points]) and 51% had resolution of NASH (treatment difference, 32 percentage points [CI, 13 to 51 percentage points]) (P < 0.001 for each). Pioglitazone treatment also was associated with improvement in individual histologic scores, including the fibrosis score (treatment difference, -0.5 [CI, -0.9 to 0.0]; P = 0.039); reduced hepatic triglyceride content from 19% to 7% (treatment difference, -7 percentage points [CI, -10 to -4 percentage points]; P < 0.001); and improved adipose tissue, hepatic, and muscle insulin sensitivity (P < 0.001 vs. placebo for all). All 18-month metabolic and histologic improvements persisted over 36 months of therapy. The overall rate of adverse events did not differ between groups, although weight gain was greater with pioglitazone (2.5 kg vs. placebo).

LIMITATION

Single-center study.

CONCLUSION

Long-term pioglitazone treatment is safe and effective in patients with prediabetes or T2DM and NASH.

PRIMARY FUNDING SOURCE

Burroughs Wellcome Fund and American Diabetes Association.

Deployment Technique and Histopathological Evaluation of an Endoluminal Vascular Prosthesis Used to Repair an Iliac Artery Aneurysm

Purpose:

To describe the deployment technique, function, and gross healing of an endoluminal vascular prosthesis deployed in a high-risk patient for treatment of a common iliac artery (CIA) aneurysm.

Methods:

An 82-year-old, high-risk male with a 4-cm-diameter CIA aneurysm approximately 4.5 to 5 cm long was treated with endoluminal exclusion of the lesion using a 6-cm-long, 14-mm-internal diameter Dacron vascular prosthesis with Palmaz 308 stents sutured to either end of the graft. Intravascular ultrasound (IVUS) imaging facilitated sizing of the endograft and its accurate positioning so as to occlude both the aneurysm and the hypogastric artery, which was a potential source of retrograde flow to the aneurysm. Exclusion of the lesion and occlusion of the hypogastric artery were demonstrated on delayed angiographic images and contrast computed tomography scans obtained at 16 days postprocedure. Unfortunately, the patient died 67 days following implantation from a nonprocedure-related gastrointestinal complication.

Results:

At autopsy, the aortoiliac segment was excised and examined grossly and histologically; the evaluation confirmed complete isolation of the aneurysm by the fully expanded endoluminal prosthesis. The surface of the vascular graft was covered by a glistening, thin, fibrinous membrane. The graft material was filled with hypocellular compact fibrinous material with no evidence of endothelialization. These observations confirm preliminary sealing and isolation of the iliac artery aneurysm as healing of the endograft progressed.

Conclusions:

The data acquired from the analysis of this specimen provide information regarding the utility and early healing of an endograft used for iliac artery aneurysm exclusion. This case also exemplifies the utility of IVUS in endograft deployment.

Clinical value of liver ultrasound for the diagnosis of nonalcoholic fatty liver disease in overweight and obese patients

BACKGROUND & AIMS

Liver ultrasound (US) is usually used in the clinical setting for the diagnosis and follow-up of patients with nonalcoholic fatty liver disease (NAFLD). However, no large study has carefully assessed its performance using a semiquantitative ultrasonographic scoring system in overweight/obese patients, in comparison to magnetic resonance spectroscopy ((1) H-MRS) and histology.

METHODS

We recruited 146 patients and performed: a liver US using a 5-parameter scoring system, a liver (1) H-MRS to quantify liver fat content, and a liver biopsy to assess histology. All measurements were repeated in a subgroup of patients (n = 62) after 18 months of follow-up.

RESULTS

The performance of liver US (parenchymal echo alone) was rather modest, and significantly worse than (1) H-MRS (AUROC: 0.82 [0.69-0.94] vs. 0.96 [0.90-1.00]; P = 0.04). However, the AUROC improved when different echographic parameters were taken into account (AUROC: 0.89 [0.83-0.96], P = 0.15 against (1) H-MRS). Optimum sensitivity for liver US was achieved at a liver fat content ≥12.5%, suggesting that below this threshold, liver US is less sensitive. Liver (1) H-MRS showed a high accuracy for the diagnosis of NAFLD, and correlated strongly with histological steatosis (r = 0.73, P < 0.0001). None of the imaging tests was adequate enough to predict changes over time in histology.

CONCLUSIONS

Despite its widespread use, liver US has several important limitations that healthcare providers should recognize, particularly because of its low sensitivity. Using a combination of echographic parameters, liver US showed a significant improvement in its diagnostic performance, but still was of limited value for monitoring treatment over time.

Relationship between disease severity, hyperinsulinemia, and impaired insulin clearance in patients with nonalcoholic steatohepatitis

Hyperinsulinemia is believed to play a key role in the pathogenesis of nonalcoholic steatohepatitis (NASH) and associated cardiovascular risk. However, the relative contribution of insulin clearance to hyperinsulinemia and its relationship to liver histology have not been carefully evaluated before. To examine this, we enrolled 190 patients (32 without nonalcoholic fatty liver disease [NAFLD], 36 with simple steatosis [SS], and 122 with biopsy-proven NASH). Insulin secretion and hepatic insulin clearance were estimated by means of an oral glucose tolerance test, whereas peripheral insulin sensitivity and whole-body insulin clearance were measured during a euglycemic insulin clamp. A liver biopsy was performed to assess histology (grade/stage). Patients with NASH had similar hepatic insulin sensitivity, compared to patients with SS, but more severe adipose tissue insulin resistance and worse hyperinsulinemia. Patients with SS and NASH had a similar ∼30% reduction (P<0.01) in hepatic insulin clearance, when compared to patients without NAFLD. Reduced hepatic insulin clearance was not associated with severity of inflammation, ballooning, and fibrosis. In contrast, worse histological inflammation and ballooning (but not steatosis or fibrosis) were associated with a progressive reduction in whole-body insulin clearance (P<0.001 for trend). There was no significant difference in insulin secretion between patients with SS versus NASH.

CONCLUSION

Decreased hepatic insulin clearance develops with a mild increase in liver fat (LFAT) accumulation. It appears to be largely driven by hepatic steatosis, whereas steatohepatitis is more closely associated with reduced whole-body insulin clearance. Hyperinsulinemia in NAFLD correlated strongly with impaired insulin clearance, but not with insulin secretion. Strategies that reduce LFAT and improve insulin clearance hold the potential to revert the unfavorable effects of hyperinsulinemia in these patients.

Limited value of plasma cytokeratin-18 as a biomarker for NASH and fibrosis in patients with non-alcoholic fatty liver disease

BACKGROUND & AIMS

Liver biopsy is the only reliable way of diagnosing and staging NASH but its invasive nature limits its use. Plasma caspase-generated cytokeratin-18 fragments (CK-18) have been proposed as a non-invasive alternative. We studied its clinical value in a large multiethnic NAFLD population and examined its relationship to clinical/metabolic/histological parameters.

METHODS

424 middle-aged subjects in whom we measured adipose tissue, liver and muscle insulin resistance (IR), liver fat by MRS (n=275) and histology (n=318).

RESULTS

Median CK-18 were elevated in patients with vs. without NAFLD by MRS (209 [IQR: 137-329] vs. 122 [IQR: 98-155]U/L) or with vs. without NASH (232 [IQR: 151-387] vs. 170 [IQR: 135-234]U/L, both p<0.001). Plasma CK-18 raised significantly with any increase in steatosis, inflammation and fibrosis, but there was a significant overlap across disease severity. The CK-18 AUROC to predict NAFLD, NASH or fibrosis were 0.77 (95% CI=0.71-0.84), 0.65 (95% CI=0.59-0.71) and 0.68 (95% CI=0.61-0.75), respectively. The overall sensitivity/specificity for NAFLD, NASH and fibrosis were 63% (57-70%)/83% (69-92%), 58% (51-65%)/68% (59-76%) and 54% (44-63%)/85% (75-92%), respectively. CK-18 correlated most strongly with ALT (r=0.57, p<0.0001) and adipose tissue IR (insulin-suppression of FFA: r=-0.43; p<0.001), less with steatosis, lobular inflammation and fibrosis (r=0.28-0.34, all p<0.001), but not with ballooning, BMI, metabolic syndrome or T2DM.

CONCLUSIONS

Plasma CK-18 has a high specificity for NAFLD and fibrosis, but its limited sensitivity makes it inadequate as a screening test for staging NASH. Whether combined as a diagnostic panel with other biomarkers or clinical/laboratory tests may prove useful requires further study.

Impact of Parallel Micro-Engineered Stent Grooves on Endothelial Cell Migration, Proliferation, and Function

Background—

Stent luminal surface characteristics influence surface endothelialization. We hypothesize that luminal stent microgrooves created in the direction of coronary flow accelerate endothelial cell migration, resulting in lower levels of neointimal formation.

Methods and Results—

Surface coverage efficiency was evaluated in vitro by allowing human aortic endothelial cells (HAEC) to migrate onto microgrooved (G) or smooth (NG) surfaces. HAEC functionality was assessed by proliferation rate, apoptosis rate, nitric oxide production, and inflammatory markers TNF-α and VCAM-1 expression. Early endothelialization and restenosis studies were performed using the porcine coronary injury model. Stainless steel stents of identical design with (GS) and without (NGS) luminal microgrooves were used. The commercially available Multi-Link Vision (MLVS) stent of identical design was used as a control. The degree of GS and NGS surface endothelialization was compared at 3 days. Biocompatibility and tissue response outcomes were evaluated at 28 days. The in vitro study demonstrated that at 7 days the presence of surface microgrooves increased HAEC migration distance >2-fold. Cell proliferation rate and nitric oxide production were increased and apoptosis rate was decreased. There was no difference in inflammatory marker expression. At 3 days, coronary artery stent endothelialization was significantly increased in GS compared with NGS (81.3% versus 67.5%, P =0.0002). At 28 days, GS exhibited lower neointimal thickness compared with either NGS (21.1%, P =0.011) or MLVS (40.8%, P =0.014).

Conclusion—

Parallel microgrooves on coronary stent luminal surfaces promote endothelial cell migration and positively influence endothelial cell function, resulting in decreased neointimal formation in the porcine coronary injury model.

Effect of adipose tissue insulin resistance on metabolic parameters and liver histology in obese patients with nonalcoholic fatty liver disease

The role of adipose tissue insulin resistance in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) remains unclear. To evaluate this, we measured in 207 patients with NAFLD (age = 51 ± 1, body mass index = 34.1 ± 0.3 kg/m(2) ) and 22 controls without NAFLD (no NAFLD) adipose tissue insulin resistance by means of a validated index (Adipo-IR(i) = plasma free fatty acids [FFA] x insulin [FPI] concentration) and as the suppression of plasma FFA during an oral glucose tolerance test and by a low-dose insulin infusion. We also explored the relationship between adipose tissue insulin resistance with metabolic and histological parameters by dividing them based on quartiles of adipose tissue insulin resistance (Adipo-IR(i) quartiles: Q1 = more sensitive; Q4 = more insulin resistant). Hepatic insulin resistance, measured as an index derived from endogenous glucose production x FPI (HIRi), and muscle insulin sensitivity, were assessed during a euglycemic insulin clamp with 3-[(3) H] glucose. Liver fat was measured by magnetic resonance imaging and spectroscopy, and a liver biopsy was performed to assess liver histology. Compared to patients without steatosis, patients with NAFLD were insulin resistant at the level of adipose tissue, liver, and skeletal muscle and had higher plasma aspartate aminotransferase and alanine aminotransferase, triglycerides, and lower high-density lipoprotein cholesterol and adiponectin levels (all P < 0.01). Metabolic parameters, hepatic insulin resistance, and liver fibrosis (but not necroinflammation) deteriorated as quartiles of adipose tissue insulin resistance worsened (all P < 0.01).

CONCLUSION

Adipose tissue insulin resistance plays a key role in the development of metabolic and histological abnormalities of obese patients with NAFLD. Treatment strategies targeting adipose tissue insulin resistance (e.g., weight loss and thiazolidinediones) may be of value in this population.

Role of ethnicity in overweight and obese patients with nonalcoholic steatohepatitis

The role of ethnicity in determining disease severity in nonalcoholic steatohepatitis (NASH) remains unclear. We recruited 152 patients with biopsy-proven NASH, 63% of whom were Hispanic and 37% of whom were Caucasian. Both groups were well matched for age, sex, and total body fat. We measured: (1) liver fat by magnetic resonance imaging and spectroscopy; (2) fasting plasma glucose, fasting plasma insulin (FPI), and free fatty acid (FFA) levels; (3) total body fat by dual energy x-ray absorptiometry (DXA); (4) liver and muscle insulin sensitivity (insulin clamp with 3-[(3)H] glucose); (5) insulin resistance at the level of the liver (fasting endogenous glucose production derived from 3-[(3)H] glucose infusion × FPI) and adipose tissue (fasting FFA × FPI). Liver fat was slightly, but not significantly, higher in Hispanic vs. Caucasian patients (27 ± 2% vs. 24 ± 2%, p = 0.16). However, this trend did not translate into worse liver steatosis, necroinflammation or fibrosis. Patients with NASH had severe hepatic, adipose tissue and muscle insulin resistance versus healthy subjects without NASH nonalcoholic fatty liver disease, but there were no differences between both ethnic groups on these parameters. However, Hispanics versus Caucasians with type 2 diabetes mellitus (T2DM) had a trend for worse hepatic/adipose tissue insulin resistance and fibrosis.

CONCLUSION

When Hispanic and Caucasian patients with NASH are well matched for clinical parameters, particularly for adiposity, slightly higher liver fat content is not associated with worse hepatic insulin resistance or more severe NASH on histology. Hispanic ethnicity does not appear to be a major determinant of disease severity in NASH, although those with diabetes may be at greater risk of fibrosis. Given the higher risk of T2DM in Hispanics, long-term studies are needed to define their risk of disease progression.

Metabolic factors in the development of hepatic steatosis and altered mitochondrial gene expression in vivo

The objective of the study was to understand the role in vivo of elevated plasma free fatty acids (FFA), insulin, and glucose levels in the development of steatosis and altered mitochondrial gene/protein expression. We studied 4 groups of Sprague-Dawley rats: (1) high-fat diet (HFD), (2) high-dose streptozotocin-induced diabetes (T1DM), (3) low-dose streptozotocin-induced diabetic rats on an HFD (T2DM), and (4) controls. Liver histology and expression of genes/proteins related to mitochondrial fatty acid oxidation and biogenesis were analyzed. Despite an attempt to compensate by increasing expression of genes of fatty acid oxidation (carnitine palmitoyl transferase-1/medium chain acyl-CoA dehydrogenase), the HFD and diabetic groups developed marked steatosis and suffered a significant reduction in mitochondrial biogenesis gene expression (nuclear respiratory factor 1/transcriptional factor A, mitochondrial). In T2DM rats, the combination of high glucose and FFA unexpectedly did not lead to greater fat accumulation than HFD alone. Greater steatosis in HFD vs T2DM (P < .001) correlated with impairment in the gene expression of PPAR-α (ie, fatty acid oxidation) and PGC1α, a major coactivator for mitochondrial biogenesis. Steatosis was not severe in insulin-deficient T1DM rats despite very elevated FFA and glucose levels. Increased carnitine palmitoyl transferase-1/medium chain acyl-CoA dehydrogenase/PPAR-α gene expression suggested inadequate adaptation to high FFA in both T1DM/T2DM rats. Hyperinsulinemia combined with elevated FFA is the key metabolic factor driving hepatic lipogenesis in vivo (HFD rats). Mitochondrial biogenesis (nuclear respiratory factor 1; transcriptional factor A, mitochondrial) is highly susceptible to FFA-induced steatosis. In contrast, hyperglycemia does not have an additive effect (T2DM) and leads to only a modest degree of steatosis in the absence of hyperinsulinemia, even when FFA are extremely elevated as in T1DM rats.

Neointimal vascularization and intimal thickening in response to self‐expanding stents: a swine model

BACKGROUND

Neovascularization has been suggested as a biological response to vessel injury and associated with restenosis. Self-expanding (SE) stents generate a lasting force on the arterial wall and may lead to an increased arterial response with time.

OBJECTIVES

To characterize the process of neovascularization with SE stents, and to correlate it with vascular injury, inflammation and intimal proliferation.

METHODS

Sixty-nine SE stents were im-planted in 37 non-atherosclerotic pigs.Detailed, multisection histological examination was performed at 15 days, 1, 3 and 6 months post-deployment. Neo-vascularization in addition to other histologic parameters where determined and scored.

RESULTS

Intravascular-ultrasound-based average vessel diameter was 3.3 +/- 0.04 mm; stent size was 3.75 +/- 0.35 mm leading to an oversizing ratio of 1.14 +/- 0.15. Intimal thickness (IT), inflammatory score (IFS) and vascularization score(VAS) reached peak values at three months (IT = 344 +/- 202 1m, IFS = 0.91 +/- 0.5, and VAS = 1.56 +/- 0.8). In contrast,the injury score (INS) continued to increase at all time-points, with maximum value at six months (INS = 1.6 +/- 0.7). Both vascularization and inflammation indices increased with an increase in the injury score (p < 0.01). When vessels were divided according to vascularization score (VAS <1.5 and >1.5) there was a significant difference in IT.

CONCLUSION

Neovascularization in response to SE stents is a time-dependent phenomenon and interacts with injury and inflammation. The remodeling of the vessel wall caused by the sustained force of the SE stent on the arterial wall enhances the formation of neovascularization. Neointimal formation is related to the degree of neovascularization.

In vivo comparison between optical coherence tomography and intravascular ultrasound for detecting small degrees of in-stent neointima after stent implantation

OBJECTIVES

The purpose of this study was to evaluate optical coherence tomography (OCT) for detecting small degrees of in-stent neointima (ISN) after stent implantation compared with intravascular ultrasound (IVUS).

BACKGROUND

The importance of detecting neointimal coverage of stent struts has grown with the appreciation of the increased risk for late stent thrombosis after drug-eluting stent (DES) implantation. Intravascular ultrasound, the current standard for evaluating the status of DES, lacks the resolution to detect the initial neointimal coverage. Optical coherence tomography has greater resolution but has not yet been compared with IVUS in vivo with histological correlation for validation.

METHODS

Intravascular ultrasound and OCT were performed with motorized pullback imaging in 6 pigs across 33 stents, 1 month after implantation. Each pig was euthanized, and histological measurements of vessel, stent, and lumen dimensions were performed in 3 sections of each stent. A small degree of ISN was defined as occupying <30% of the stent area measured with histology. The IVUS, OCT, and histological assessment of ISN were compared in matched cross-sections of the stents with a small degree of ISN.

RESULTS

Eleven stents had a small degree of ISN (average ISN area: 1.26 +/- 0.46 mm(2), and percent area obstruction: 21.4 +/- 5.2%). Compared with histology, the diagnostic accuracy of OCT (area under the receiver operating characteristic curve [AUC] = 0.967, 95% confidence interval [CI] 0.914 to 1.019) was higher than that of IVUS (AUC = 0.781, 95% CI 0.621 to 0.838).

CONCLUSIONS

Optical coherence tomography detects smaller degrees of ISN more accurately than IVUS and might be a useful method for identifying neointimal coverage of stent struts after DES implantation.

A placebo-controlled trial of pioglitazone in subjects with nonalcoholic steatohepatitis

BACKGROUND

No pharmacologic therapy has conclusively proved to be effective for the treatment of nonalcoholic steatohepatitis, which is characterized by insulin resistance, steatosis, and necroinflammation with or without centrilobular fibrosis. Pioglitazone is a thiazolidinedione that ameliorates insulin resistance and improves glucose and lipid metabolism in type 2 diabetes mellitus.

METHODS

We randomly assigned 55 patients with impaired glucose tolerance or type 2 diabetes and liver biopsy-confirmed nonalcoholic steatohepatitis to 6 months of treatment with a hypocaloric diet (a reduction of 500 kcal per day in relation to the calculated daily intake required to maintain body weight) plus pioglitazone (45 mg daily) or a hypocaloric diet plus placebo. Before and after treatment, we assessed hepatic histologic features, hepatic fat content by means of magnetic resonance spectroscopy, and glucose turnover during an oral glucose tolerance test ([14C]glucose given with the oral glucose load and [3H]glucose given by intravenous infusion).

RESULTS

Diet plus pioglitazone, as compared with diet plus placebo, improved glycemic control and glucose tolerance (P<0.001), normalized liver aminotransferase levels as it decreased plasma aspartate aminotransferase levels (by 40% vs. 21%, P=0.04), decreased alanine aminotransferase levels (by 58% vs. 34%, P<0.001), decreased hepatic fat content (by 54% vs. 0%, P<0.001), and increased hepatic insulin sensitivity (by 48% vs. 14%, P=0.008). Administration of pioglitazone, as compared with placebo, was associated with improvement in histologic findings with regard to steatosis (P=0.003), ballooning necrosis (P=0.02), and inflammation (P=0.008). Subjects in the pioglitazone group had a greater reduction in necroinflammation (85% vs. 38%, P=0.001), but the reduction in fibrosis did not differ significantly from that in the placebo group (P=0.08). Fatigue and mild lower-extremity edema developed in one subject who received pioglitazone; no other adverse events were observed.

CONCLUSIONS

In this proof-of-concept study, the administration of pioglitazone led to metabolic and histologic improvement in subjects with nonalcoholic steatohepatitis. Larger controlled trials of longer duration are warranted to assess the long-term clinical benefit of pioglitazone. (ClinicalTrials.gov number, NCT00227110 [ClinicalTrials.gov] .).

Intracoronary photodynamic therapy reduces neointimal growth without suppressing re-endothelialisation in a porcine model

OBJECTIVE

To examine the effects of intracoronary PhotoPoint photodynamic therapy (PDT) with a new photosensitiser, MV0611, in the overstretch balloon and stent porcine models of restenosis.

METHODS

28 pigs were injected with 3 mg/kg of MV0611 systemically 4 h before the procedure. Animals were divided into either the balloon overstretch injury (BI) group (n = 19) or the stented group (n = 9). After BI, a centred delivery catheter was positioned in the artery to cover the injured area, and light (532 nm, 125 J/cm(2)) was applied to activate the drug (n = 10). Control arteries (n = 9) were not activated by light. In the stented group, the drug was light activated before stent deployment. Serial sections of vessels were processed 14 days after treatment in the BI group and 30 days after treatment in the stented group for histomorphometric or immunohistochemical analysis.

RESULTS

Intracoronary PDT significantly reduced intimal thickness in both BI and stented arteries (about 65%: 0.22 (SEM 0.05) mm v 0.62 (0.05) mm, p < 0.01; and about 26%: 0.40 (0.04) mm v 0.54 (0.04) mm, p < 0.01, respectively). PDT increased luminal area by

CONCLUSION

Intracoronary PhotoPoint PDT with MV0611 reduces intimal proliferation without suppressing re-endothelialisation in a porcine model of restenosis.

Collapse

Key Words Collapse

MESH Headings

• Angioplasty, Balloon
• Animals
• Cell Proliferation
• Coronary Restenosis/prevention & control
• Coronary Vessels/injuries
• Feasibility Studies
• Female
• Immunohistochemistry
• Male
• Mesoporphyrins/pharmacokinetics
• Mesoporphyrins/therapeutic use
• Photochemotherapy/methods
• Photosensitizing Agents/pharmacokinetics
• Photosensitizing Agents/therapeutic use
• Random Allocation
• Stents
• Swine
• Tunica Intima

Collapse

Grants Collapse

A new percutaneous porcine coronary model of chronic total occlusion

OBJECTIVE

Chronic total occlusion (CTO) of coronary arteries represents a challenge for percutaneous treatment. Although ameroid constrictors have been used to create CTOs from extrinsic compression of coronary arteries, this model is not suitable for evaluation of novel angioplasty equipment. Thus, the objective of this study was to create a new percutaneous animal model of CTO.

METHODS

To create an animal model of CTO, we implanted copper-plated stents in the left circumflex coronary arteries of 18 pigs, and assigned the pigs to early group (n = 6; sacrifice at approximately 1 week), intermediate group (n = 6; sacrifice at approximately 4 weeks), and late group (n = 6; sacrifice at approximately 8 weeks).

RESULTS

Follow-up angiography prior to sacrifice revealed complete occlusion in 14 of 17 animals, with the subtotal occlusive lesions (mean 60% stenosis) only in the early group. Most of the pigs with total occlusions (12 of 14) showed bridging collateral flow greater than or equal to grade 2 (grade 2: 4; grade 3: 8). Histology revealed organizing thrombus in the early group with persistent inflammation, and organized thrombus with fibrosis and calcification in the intermediate and late groups. Interestingly, there were fibrotic components in the proximal and distal edges of the occlusions with softer, organizing thrombus in the middle of the CTO in the late group, suggesting that the major areas of difficulty are at the entrance and exit segments of the CTO with percutaneous recanalization.

CONCLUSION

This study shows the feasibility and reproducibility of a new porcine coronary percutaneous CTO model. This model may be useful in improving our percutaneous treatment of CTO.

The effect of variable release kinetics on Paclitaxel efficacy from a drug eluting stent in a porcine model

AIMS

Paclitaxel is a potent and effective inhibitor of neointimal proliferation after coronary stenting. The Conor stent loaded with Paclitaxel can be programmed with multi-parameter matrix of dose, temporal release profiles and release pathways. The aim of this study was to determine the most efficacious dose and release pattern of Paclitaxel in a porcine model and parallels the PISCES trial.

METHODS

32 farm pigs were implanted with Conor stents loaded with 10 or 30 microg of Paclitaxel with, 10 or 30 day and mural or bidirectional release patterns. Angiographic and histomorphometric analysis was -performed at 30 and 90 days.

RESULTS

All doses of Paclitaxel were angiographically superior to control (P < 0.01). At 30 days, intimal thickness was similar between Pisces D4 (30 microg/10 days, bidirectional release), D5 (10 microg/30 day mural) and D6 (30 microg/30 day, mural) with D4 having the lowest intimal thickness (167+/-59 microm). There was a significant increase in the mural injury associated with D4 in comparison to all other doses (P < 0.00001). At 90 days D4 was significantly worse in comparison to Pisces D5 and D6; (P < 0.01) and Pisces D5 and D6 were similar to controls.

CONCLUSIONS

10 day release of Paclitaxel may be too short a period to inhibit neointimal proliferation after coronary stenting, or the rapid release of Paclitaxel may induce chemical injury causing secondary insult to the artery resulting in a rebound increase in intimal thickness at 90 days. These data parallel clinical findings in the PISCES trial.

Segmental vessel wall shear stress and neointimal formation after sirolimus-eluting stent implantation: physiological insights in a porcine coronary model

BACKGROUND

Low vessel-wall shear stress promotes atherosclerosis and restenosis. We conducted serial analysis of vessel-wall shear stress following placement of metal and sirolimus (SRL) stents to determine the relationship between shear stress and neointima.

METHODS

Serial quantitative coronary angiography, intracoronary ultrasound (IVUS), and Doppler flow analysis were performed at baseline, immediately poststent, and at 30 and 90 days on 16 stents (metal, n = 8; SRL, n = 8) implanted in the coronary arteries of eight miniswine. Segmental vessel-wall shear stress (dyn/cm2) was calculated at 10 sections within the stent and normalized to the average proximal and distal reference vessel shear stress using IVUS and hyperemic average peak flow velocity. At 90 days, histological analysis was completed to determine vessel-wall morphometry on corresponding sections from each stent.

RESULTS

Stent placement resulted in a similar degree of in-stent stenosis (-5% to 25%) and immediate post-in-stent shear stress. At 30 days, the IVUS neointimal cross-sectional area and percentage of area stenosis were significantly less in SRL (1.2+/-0.8 mm2; 12.7+/-8.5%) versus metal stents (2.3+/-0.4 mm2; 28.2+/-3.4%, P < .003). In-stent normalized shear stress was less for SRL (0.93+/-0.07) versus metal (1.07+/-0.08, P = .002) stents. At 90 days, the mean neointimal area was similar for the SRL (2.50+/-0.47 mm2) and metal stents (2.72+/-1.15 mm2). Linear regression documented a negative correlation between poststent shear stress and neointima for metal stents (r = .61, P < .0001). In the SRL stents, however, the post-in-stent shear stress had a positive correlation with neointima (r = .40, P = .0002).

CONCLUSIONS

The placement of oversized stents causes alteration of segmental vessel-wall shear stress, which appears to be an important physiological stimulus for neointimal formation, and may influence the pharmacodynamics of SRL-eluting stent in the porcine coronary model.

Novel site-specific systemic delivery of Rapamycin with perfluorobutane gas microbubble carrier reduced neointimal formation in a porcine coronary restenosis model

Earlier studies demonstrated that perfluorobutane gas microbubble carrier (PGMC) adheres to injured arteries and enhances the drug uptake specifically into the cells of the denuded vessel segment. The purpose of this study was to investigate the effect of PGMC-based systemic delivery of Rapamycin on expression of p27 in vascular tissue and restenosis in porcine coronary arteries after stent implantation. Eight pigs underwent coronary stent implantation (three stents per animal). Five pigs were treated with i.v. injection of PGMC with 2 mg of Rapamycin and three animals served as control. Four hours postprocedure, three pigs were sacrificed and stented segments were analyzed by high-performance liquid chromatography (HPLC) and Western blot. In chronic experiments, five pigs (15 stent sites) were sacrificed at 28 days following intervention and vessels were perfusion-fixed. HPLC of the treated arteries demonstrated high drug concentration in the vessel tissue, and Western blot analysis showed elevated expression of p27 at 4 hr postprocedure. Histomorphometry revealed significantly reduced (by 40%) neointimal formation in the PGMC/Rapamycin group compared with controls (1.84 +/- 0.84 vs. 4.77 +/- 1.71 mm2, respectively; P < 0.001). In the porcine coronary model, site-specific systemic delivery of Rapamycin utilizing PGMC resulted in overexpression of p27 and a significant reduction of neointimal formation within the stented segments.

Systemic targeted delivery of antisense with perflourobutane gas microbubble carrier reduced neointimal formation in the porcine coronary restenosis model

HYPOTHESIS

The antisense phosphorodiamidate morpholino oligomer (PMO), AVI-4126, has been effective in reducing neointimal formation in animal models following delivery by pluronic gels, local delivery catheters and coated stents. Greater flexibility of repeated-dosage regimens and reduced procedure complexity may be provided by systemic injection of AVI-4126 bound to perfluorobutane gas microbubble carriers. The purpose of this study was to investigate the effects of perfluorocarbon gas microbubble carrier (PGMC)-based systemic delivery of AVI-4126 on expression of the c-myc in vascular tissue and restenosis after stent implantation.

METHODS

Seven pigs underwent stent implantation (3 stents/animal). Five pigs received IV injection of PGMC and 2 mg of AVI-4126 (AVI BioPharma). Two served as control. Four hours postprocedure, 3 pigs were sacrificed and stented segments analyzed by high-performance liquid chromatography (HPLC) and Western blot. In chronic experiments, 4 pigs (12 stent sites) were sacrificed at 28 days.

RESULTS

HPLC analysis of plasma samples of treated animals showed minimal presence of AVI-4126. HPLC of the treated arteries demonstrated easily detected concentrations of AVI-4126. Western blot analysis of the stented vessels demonstrated modest inhibition of c-myc. Morphometry showed that the neointimal area was significantly reduced in the AVI-4126/PGMC group compared with control (2.63+/-1.99 vs. 4.77+/-.1.71 mm2, respectively, P<.05).

CONCLUSION

In the porcine coronary stent model, systemic targeted delivery of AVI-4126 using PGMC carrier significantly inhibited neointimal formation.

Advanced c-myc antisense (AVI-4126)-eluting phosphorylcholine-coated stent implantation is associated with complete vascular healing and reduced neointimal formation in the porcine coronary restenosis model

An advanced six-ring morpholino backbone c-myc antisense (AVI-4126) was shown to inhibit c-myc expression and intimal hyperplasia after local catheter delivery in a porcine balloon injury model. The purpose of this study was to investigate the effects of an AVI-4126-eluting phosphorylcholine-coated (PC) stent on c-myc expression restenosis and vascular healing after stent implantation in porcine coronary arteries. PC stents were loaded with AVI-4126 using soak trap. Nine pigs underwent AVI-4126 PC coronary stent implantation (two stents/animal). Two to six hours postprocedure, three pigs were sacrificed and stented segments were analyzed by Western blot for c-myc expression. In chronic experiments, six pigs (12 stent sites) were sacrificed at 28 days following intervention and vessels were perfusion-fixed. High-performance liquid chromatography analysis of plasma samples showed minimal presence of the antisense. Western blot analysis of the stented vessels demonstrated inhibition of c-myc expression at 2 and 6 hr after procedure. Quantitative histologic morphometry showed that the neointimal area was significantly reduced (by 40%) in the antisense-coated group compared with control (2.3 +/- 0.7 vs. 3.9 +/- 0.8 mm(2), respectively; P = 0.0077). Immunostaining and electron microscopy demonstrated complete endothelialization, without fibrin deposition, thrombosis, or necrosis in all implanted stents. In the porcine coronary model, an advanced c-myc-eluting PC stent blocked c-myc expression and significantly inhibited myointimal hyperplasia and allowed complete reendothelialization and healing response.

Long-term effects of polymer-based, slow-release, sirolimus-eluting stents in a porcine coronary model

BACKGROUND

Stent-based delivery of sirolimus (SRL) has shown reduction in neointimal hyperplasia and restenosis. The purpose of this study was to evaluate the chronic vascular response and the expression of cell cycle regulators after SRL-eluting stent implantation in a porcine coronary model.

METHODS

Forty-nine pigs underwent placement of 109 oversized stents (control, n=54, SRL (140 microg/cm(2)), n=55) in the coronary arteries with histologic analysis and Western blot (PCNA, p27(kip1), CD45, MCP-1, IL-2, IL-6, TNF-beta) at 3, 30, 90 or 180 days.

RESULTS

At 3 days, the mean thrombus area was similar for control (0.38+/-0.19 mm(2)) and SRL (0.29+/-0.09 mm(2)) stents. After 30 days, the mean neointimal area was significantly less for the SRL (1.40+/-0.35 mm(2)) versus the control stents (2.94+/-1.28 mm(2), p<0.001). At 90 and 180 days, the mean neointimal area was similar for the SRL (3.03+/-0.92 and 3.34+/-0.99 mm(2)) as compared with control stents (3.45+/-1.09 and 3.65+/-1.23 mm(2)). Western blot analysis demonstrated an increased expression of p27(kip1) in the vessel wall at 90 days for the SRL versus control stents (p=0.05) but with increased levels of PCNA in the SRL as compared with control stents (p=0.003).

CONCLUSION

SRL-eluting stents favorably modulate neointimal formation for 30 days in the porcine coronary model. Long-term inhibition of neointimal hyperplasia is not sustained presumably due to delayed cellular proliferation despite increased levels of the cyclin-dependent kinase p27(kip1) in the vessel wall.

Transplantation of autologous endothelial cells induces angiogenesis

This study examined the feasibility and efficacy of autologous endothelial cell (EC) transplantation using a fibrin matrix in the ischemic myocardium of sheep. Four weeks after placing an ameroid constrictor in the circumflex artery of 12 adult sheep, four animals (EC group) were subjected to EC transplantation. In four others (saline [SAL] group) saline with added inactivated cells was injected and four animals served as controls. Eight weeks after treatment the animals were sacrificed to assess histology and ultrastructure. Eight weeks after injection, ventricular function was markedly improved in the EC transplant group, but had deteriorated in the SAL and control groups. Myocardial blood flow was also increased in the EC group. Histology and electron microscopy revealed extensive neovascularization after EC transplantation and improved myocardial appearance. Heterotopic transplantation of EC within a fibrin matrix enhances neovascularization, increases myocardial blood flow, and improves left ventricular function.

Intramural coronary delivery of advanced antisense oligonucleotides reduces neointimal formation in the porcine stent restenosis model

OBJECTIVES

We evaluated the long-term influence of intramural delivery of advanced c-myc neutrally charged antisense oligonucleotides (Resten-NG) on neointimal hyperplasia after stenting in a pig model.

BACKGROUND

Neointimal hyperplasia after percutaneous coronary interventions is one of the key components of the restenotic process. The c-myc is a critical cell division cycle protein involved in the formation of neointima.

METHODS

In short-term experiments, different doses (from 500 microg to 5 mg) of Resten-NG or saline were delivered to the stent implantation site with an infiltrator delivery system (Interventional Technologies, San Diego, California). Animals were euthanized at 2, 6 and 18 h after interventions, and excised vessels were analyzed for c-myc expression by Western blot. In long-term experiments, either saline or a dose of 1, 5 or 10 mg of Resten-NG was delivered in the same fashion, and animals were euthanized at 28 days after the intervention.

RESULTS

Western blot analysis demonstrated inhibition of c-myc expression and was dose dependent. Morphometry showed that the intimal area was 3.88 +/- 1.04 mm(2) in the control. There was statistically significant reduction of intimal areas in the 5 and 10 mg groups (2.01 +/- 0.66 and 1.95 +/- 0.91, respectively, p < 0.001) but no significant reduction in the 1 mg group (2.81 +/- 0.56, p > 0.5) in comparison with control.

CONCLUSIONS

This study demonstrated that intramural delivery of advanced c-myc neutrally charged antisense morpholino compound completely inhibits c-myc expression and dramatically reduces neointimal formation in a dose dependent fashion in a porcine coronary stent restenosis model, while allowing for complete vascular healing.

Stent-based delivery of sirolimus reduces neointimal formation in a porcine coronary model

BACKGROUND

The purpose of this study was to determine the efficacy of stent-based delivery of sirolimus (SRL) alone or in combination with dexamethasone (DEX) to reduce in-stent neointimal hyperplasia. SRL is a potent immunosuppressive agent that inhibits SMC proliferation by blocking cell cycle progression.

METHODS AND RESULTS

Stents were coated with a nonerodable polymer containing 185 microgram SRL, 350 microgram DEX, or 185 microgram SRL and 350 microgram DEX. Polymer biocompatibility studies in the porcine and canine models showed acceptable tissue response at 60 days. Forty-seven stents (metal, n=13; SRL, n=13; DEX, n=13; SRL and DEX, n=8) were implanted in the coronary arteries of 16 pigs. The tissue level of SRL was 97+/-13 ng/artery, with a stent content of 71+/-10 microgram at 3 days. At 7 days, proliferating cell nuclear antigen and retinoblastoma protein expression were reduced 60% and 50%, respectively, by the SRL stents. After 28 days, the mean neointimal area was 2.47+/-1.04 mm(2) for the SRL alone and 2.42+/-1.04 mm(2) for the combination of SRL and DEX compared with the metal (5.06+/-1.88 mm(2), P<0.0001) or DEX-coated stents (4.31+/-3.21 mm(2), P<0.001), resulting in a 50% reduction of percent in-stent stenosis.

CONCLUSIONS

Stent-based delivery of SRL via a nonerodable polymer matrix is feasible and effectively reduces in-stent neointimal hyperplasia by inhibiting cellular proliferation.

Blood flow and thrombus formation determine the development of stent neointima

To establish a relationship between flow, acute thrombus formation, and late intimal formation in implanted arterial stents, canine femoral arteries with normal blood flow were compared to contralateral femoral arteries with restricted blood flow. Thrombocyte activity over the stent segment was evaluated for 3 h after stent placement with nuclear scanning, following administration of In-111 labeled platelets. To evaluate long-term stent patency in relationship to arterial flow, an additional group of dogs were subjected to long-term observation. Matched, symmetrically implanted femoral stents with normal and restricted flow were explanted at 1, 12, and 24 weeks for histological analysis and comparative measurement of neointimal thickness. Angiographic studies were performed before and after nuclear scan in the acute animals and before explant in the chronic animals. Acutely, heparinization prevented subocclusive or occlusive thrombus, regardless of flow. In the absence of heparinization, normal arterial blood flow did not prevent thrombus formation on stents. Chronically, stents with flow restriction had significantly greater neointimal formation in comparison with unrestricted stents. Histological studies suggested that the stent neointima resulted from progressive replacement of stent thrombus.

Relationship between blood flow, thrombus, and neointima in stents

PURPOSE

To establish a relationship between flow, acute thrombus formation, and late intimal hyperplasia in arterial stents.

MATERIALS AND METHODS

To compare short-term stent patency in the canine femoral artery with normal flow to that in the opposite femoral artery with restricted flow, 24 dogs were subdivided in four groups: groups 1 (no intravenous heparin) and 2 (intravenous heparin) had unilateral flow restriction by surgically created stenosis, downstream of a Palmaz stent. Group 3 (no intravenous heparin) and 4 (intravenous heparin) had sham surgical exposure of the corresponding arterial segment, without flow restriction. Thrombocyte activity over the stent segment was evaluated for 3 hours after stent placement with nuclear scanning, after administration of indium-111-labeled platelets. To evaluate long-term stent patency in relationship to arterial flow, 14 additional dogs were subjected to long-term observation. Matched, symmetrically implanted femoral stents with normal and restricted flow, were explanted at 1, 12, and 24 weeks for histologic analysis and comparative measurement of neointimal thickness. Angiographic studies were performed before and after nuclear scanning in the short-term study group and before explant in the long-term animal group.

RESULTS

In the short-term, groups 2 and 4 showed neither increased platelet uptake nor angiographically demonstrable thrombus. Group 1 had increased platelet uptake and occlusive or subocclusive angiographic thrombus. Group 3 had increased platelet uptake and angiographic thrombus in one instance. In the long-term, stents with flow restriction had significantly greater neointimal formation in comparison with unrestricted stents. Histologic studies suggested that the stent neointima resulted from progressive replacement of stent thrombus.

CONCLUSION

Regardless of flow condition, intravenous heparinization is necessary to prevent thrombus formation in the stent lumen. Within the experimental parameters of this study, low flow and absent heparinization consistently lead to stent thrombosis. Stent implantation under low flow is associated with increased neointima formation. It is not known whether this is preventable by antithrombotic medication.

Cokeromyces recurvatus infection in a bone marrow transplant recipient

Diarrhea is common after bone marrow transplants. We report Cokeromyces recurvatus infection in a transplant recipient with diarrhea. Treatment with mystatin was effective.

Deployment technique and histopathological evaluation of an endoluminal vascular prosthesis used to repair an iliac artery aneurysm

PURPOSE

To describe the deployment technique, function, and gross healing of an endoluminal vascular prosthesis deployed in a high-risk patient for treatment of a common iliac artery (CIA) aneurysm.

METHODS

An 82-year-old, high-risk male with a 4-cm-diameter CIA aneurysm approximately 4.5 to 5 cm long was treated with endoluminal exclusion of the lesion using a 6-cm-long, 14-mm-internal diameter Dacron vascular prosthesis with Palmaz 308 stents sutured to either end of the graft. Intravascular ultrasound (IVUS) imaging facilitated sizing of the endograft and its accurate positioning so as to occlude both the aneurysm and the hypogastric artery, which was a potential source of retrograde flow to the aneurysm. Exclusion of the lesion and occlusion of the hypogastric artery were demonstrated on delayed angiographic images and contrast computed tomography scans obtained at 16 days postprocedure. Unfortunately, the patient died 67 days following implantation from a nonprocedure-related gastrointestinal complication.

RESULTS

At autopsy, the aortoiliac segment was excised and examined grossly and histologically; the evaluation confirmed complete isolation of the aneurysm by the fully expanded endoluminal prosthesis. The surface of the vascular graft was covered by a glistening, thin, fibrinous membrane. The graft material was filled with hypocellular compact fibrinous material with no evidence of endothelialization. These observations confirm preliminary sealing and isolation of the iliac artery aneurysm as healing of the endograft progressed.

CONCLUSIONS

The data acquired from the analysis of this specimen provide information regarding the utility and early healing of an endograft used for iliac artery aneurysm exclusion. This case also exemplifies the utility of IVUS in endograft deployment.

Occlusion of the neonatal patent ductus arteriosus with a simple retrievable device: a feasibility study

PURPOSE

To examine the feasibility of transvenous placement of a new memory-shaped, small, retrievable coil that has a smaller-caliber delivery system than currently available devices, for closure of the patent ductus arteriosus (PDA).

METHODS

Through 4 or 5 Fr vascular sheaths and 4 or 5 Fr end-hold catheters, the coils were delivered and placed in piglets (n = 10) with PDA. The coils were made from 0.018" (0.46 mm) or 0.028" (0.71 mm) stainless steel guidewire. Mounted for delivery, the new device has the appearance of a conventional guidewire. This neonatal PDA model was created without major surgery or drugs by stenting the ductus arteriosus.

RESULTS

The memory-shaped coils were easily delivered. Coils not optimally placed were retrieved and repositioned. Occlusion of the ductus arteriosus as early as a half-hour after delivery was shown angiographically and confirmed by histopathology.

CONCLUSION

This new, small-caliber, simple device was found to be effective for closure of the PDA in this animal model. Longer-term observations are needed.

[Generalized arteriosclerosis and stent implantation. An epicritic report]

In a comprehensive demonstration we report on the long-term course of the first patient in the world to receive a vascular balloon expandable endoprosthesis (Palmaz iliac vascular stent). Iliac occlusive disease became apparent again several years after an initially successful regular balloon angioplasty of the left common iliac artery. After successful stent implantation the patient then remained completely asymptomatic over unlimited walking distance during the follow-up of 29 months, after which he died of a myocardial reinfarction. While repeat catheter angiography showed excellent incorporation of the metal stent, arteriosclerotic disease was found to have progressed in the distal abdominal aorta. Thus, the patient died of a typical complication of peripheral vascular disease, naturally reflecting the generalized character which cannot be affected by local treatment modalities. While microscopic evaluation revealed "ideal" biocompatibility of the device, portraying its high functional efficacy, the natural course of the patient reflects the purely symptomatic character of the improvement. An interesting finding was the homogeneous architecture of the neointima that developed on top of the stent. While large parts of the adjacent vessel wall had undergone significant arteriosclerotic changes this was not found in the neointima, which was made up exclusively of mature fibrocollagenous tissue.

Immunoreactive alpha transforming growth factor activity in effusions from cancer patients as a marker of tumor burden and patient prognosis

alpha Transforming growth factors (alpha-TGFs) are polypeptides that stimulate anchorage-independent growth of various nontransformed cells in vitro and are believed to be involved in autocrine stimulation of tumor cells. alpha-TGF activity is secreted by a variety of human cancers leading to the possibility that it may serve as a tumor marker. alpha-TGF activity was measured in 130 effusions from patients with various types of cancer with a radioimmunoassay using sheep antibodies against the C-terminal 17 amino acids of linear rat alpha-TGF. Forty-two % of the effusions contained immunoreactive alpha transforming growth factor (Ir-alpha-TGF) activity, including 13 of 34 (38%) breast cancer, 12 of 24 (50%) lung cancer, and 13 of 31 (42%) ovarian cancer specimens. Concentrations ranged from 1.56 to 50 ng/ml. Only 3 of 17 control effusions from noncancer patients had low levels of activity, all less than 2 ng/ml. The presence of Ir-alpha-TGF activity correlated with patients' performance status (PS) and tumor burden. It was present in 18 of 67 (27%) effusions of patients with PS less than or equal to 2 and in 23 of 33 (70%) with PS 3 or 4 (P less than 0.0001). Only 2 of 43 (4%) patients with one site of metastatic disease had detectable Ir-alpha-TGF (mean, 0.23 ng/ml); 18 of 37 (48%) with two sites (mean, 5.22 ng/ml, P less than 0.0001); and 33 of 34 (97%) with greater than two sites (mean, 5.93 ng/ml, P = 0.002). It was present in a larger percentage of effusions from breast cancer patients with estrogen- and progesterone receptor-negative tumors. Univariate analysis revealed that detectable Ir-alpha-TGF activity, PS 3 or 4, and the number of sites of disease correlated with a shorter survival. Only Ir-alpha-TGF and PS 3 or 4 retained significance in a multivariate analysis. In conclusion, Ir-alpha-TGF is frequently detectable in effusions from cancer patients, it correlates with other known adverse prognostic factors, and its presence predicts for a poor survival. Further studies of alpha-TGF activity in more readily accessible body fluids such as serum or urine are warranted.

Somatostatinoma: a case report and review of the literature

Somatostatinomas are rare endocrine tumors that were first described in 1977. In addition to the present case report, there have been 31 cases reported in the literature. We have reviewed the literature to integrate the symptoms, physical findings, diagnostic tests, treatment, and length of survival of these patients. Although the symptoms that occurred in the majority of cases were those that are seen in most patients with intra-abdominal neoplasms, symptoms relating to the presence of excess circulating somatostatin--diabetes, maldigestion, and cholelithiasis--were frequently seen. Physical findings and the results of diagnostic tests were usually nonspecific. The majority of the patients underwent radical surgical procedures (Whipple procedure or pancreatic resection). The pancreas was the most frequent site of involvement (21/31 cases), but primaries in the duodenum, ampulla of Vater, cystic duct, and jejunum have been described as well. Metastases were most frequently seen in the liver and lymph nodes. Chemotherapeutic agents were administered to 10 patients, usually as adjuvant therapy, and appear to be useful in treating recurrent and metastatic disease. The one-year survival of these patients is 48%, which is better than that for patients with carcinoma of the pancreas or biliary tree. Therefore, it is important that the diagnosis of somatostinoma be made so that the patient may be treated accordingly and followed by serial somatostatin levels for evidence of metastasis or recurrent disease.

Granulocytic sarcoma of the mandible

The case is presented of a 54-year-old black man with a mass apparently involving only the soft tissue retromolar trigone on panoramic and mandibular series radiographs. A granulocytic sarcoma involving the mandible was diagnosed on biopsy with the aid of histochemical stains, immunologic cell surface markers, and electron microscopy. The autopsy also revealed involvement of the ribs and liver.

Intrapericardial diaphragmatic hernia after subxiphoid epicardial pacemaker insertion: case reports

The first two cases of intrapericardial diaphragmatic hernia following a subxiphoid epicardial pacemaker insertion are reported. Factors deemed responsible for this rare complication in one case were previous gastrectomy with a resulting paucity of omentum, and entrance into the peritoneal cavity during the pacemaker procedure.

Interventricular fibroma and cystic renal dysplasia in a newborn

A newborn twin presented with a cardiac tumor; at autopsy microcystic dysplasia was found in the kidneys. The histology of the renal cysts were not unlike those found in many multisystem syndromes (e.g., Schwartz-Jampel, Ehlers-Danlos, and Jeune's asphyxiating thoracic dystrophy). No evidence of tuberous sclerosis or other phakomatoses were found. This case may alert other observers to carefully look for cystic dysplasia of the kidneys or other organs in association with cardiac tumors.

Phase I investigation of ametantrone

Ametantrone is the third of a family of anthracene derivatives to undergo a phase I trial in man. Sixteen patients received 33 courses of drug as a single iv dose given every 3 weeks. Escalations proceeded from 120 to 180 mg/m2. Predictable and reversible leukopenia was the dose-limiting toxic effect. Four patients developed thrombocytopenia. Nonhematologic toxic effects included a marked cumulative blue discoloration of the skin seen in all patients receiving more than three courses of the drug. This cumulative cosmetic effect may also be dose-limiting. Other nonhematologic toxic effects included: blue urine (all patients), nausea (two), vomiting (one), a blue stool (one), and reversible elevations of either SGOT or alkaline phosphatase (two). No objective responses were seen in this study. A dose of 140-160 mg/m2 is recommended as the starting dose for phase II trials in patients who have received prior chemotherapy or radiotherapy.

Utilization of a human tumor cloning system to monitor for marrow involvement with small cell carcinoma of the lung

We have compared the sensitivities of two methodologies for determining bone marrow involvement by small cell lung cancer. These methodologies included histological examination of marrow aspirations and biopsies versus growth of tumor colonies in soft agar. There were four instances in which histological study of the marrow aspirate (and biopsy) revealed metastatic small cell lung cancer. All four of the specimens formed colonies in soft agar. Thirty-four of 37 histologically negative aspirations and biopsies) showed no growth in the soft agar system. However, three histologically negative specimens formed colonies in soft agar. The cells growing in these colonies were documented to be small cell lung cancer by histology and growth in nude mice. We conclude that small cell lung cancer metastatic to bone marrow will form colonies in soft agar. Additional study is needed to determine if the soft agar system is indeed more sensitive than routine histology in detecting small cell lung cancer metastatic to bone marrow.

Malignant fibrous histiocytoma of the spermatic cord

We present 3 cases of malignant fibrous histiocytoma arising from the spermatic cord. This tumor occurs rarely in genitourinary organs and only 2 cases involving the spermatic cord have been reported previously. Recurrence rates of approximately 44 per cent of malignant fibrous histiocytoma in other sites are not improved by radiation or chemotherapy as adjuvants or primary means of treatment. Radical inguinal orchiectomy along with wide en bloc local resection is the therapy of choice.

Primary malignant fibrous histiocytoma of the intestine: intussusception of a rare neoplasm

Malignant fibrous histiocytoma, a tumor of mesenchymal tissue, is being reported with increased frequency. However, no cases of primary tumors involving the gastrointestinal tract have yet been described. This report documents a case in which the patient clinically manifested a colonic obstruction associated with intussusception. Following radical resection of the mass, close re-evaluation after one year has shown no evidence of tumor recurrence.

Early events in various forms of experimental acute tubular necrosis in rats

Metabolic and morphologic changes occurred in the kidneys of rats within 3 hours after inciting acute tubular necrosis by completely clamping the renal blood supply, by intramuscular injections of glycerol, and by subcutaneous injections of HgC12. Although the initial trend was for p-aminohippurate and tetraethylammonium transport to decrease and for oxygen consumption, ammonia production, and gluconeogenesis to increase after glycerol, all of these parameters changed in opposite directions after renal pedicle clamping and after subcutaneous HgC12 (4.7 mg. per kg;). In addition, early morphologic changes in glycerol-injected rats differed from those seen with pedicle clamping and low dose HgC12. With high dose HgC12 (25 mg. per kg.), the metabolic and morphologic changes were somewhere in between those seen with the other insults. Coinciding with early metabolic and morphologic changes, cardiac output and renal blood flow decreased soon after the glycerol was given. On the basis of our findings, we cannot ascribe all of the early metabolic and morphologic changes in the glycerol model to ischemia, and we postulate that the circulating heme proteins may be nephrotoxic to ischemic renal tissue.