Increased basal tone and hyperresponsiveness to acetylcholine and ergonovine in spasm related coronary arteries in patients with variant angina--basal coronary artery tone in patients with variant angina

In patients with variant angina, previous data have been inconclusive as to whether basal coronary artery tone is elevated at the spastic and non-spastic sites. Thus, the purpose of this study was to assess the basal coronary artery tone and the responsiveness to acetylcholine (Ach) and ergonovine (Erg) in patients with variant angina. We compared the basal coronary artery tone and the constrictive responses to Ach and Erg between 31 patients (Group 1) with variant angina in whom spasm was provoked by the low doses of Ach (intracoronary 20 micrograms) or Erg(intravenous 50 micrograms) and 35 patients (Group 2) provoked by higher doses of Ach (intracoronary 100 micrograms) or Erg (intravenous cumulative dose of 350 micrograms), and 26 control subjects. Patients with variant angina in whom spasm was provoked by low doses of Ach or Erg, had a higher incidence of mixed disease, multi-vessel spasm and higher disease activity. The basal coronary artery tone at the spastic and nonspastic sites of spasm related artery was significantly more elevated in Group 1 than that in Group 2 (44 +/- 17 vs 14 +/- 11% and 26 +/- 14 vs 16 +/- 10% respectively, P < 0.05), but not in the nonspasm related artery, The magnitudes of vasoconstrictive responses to Ach and Erg at the nonspastic sites were also greater in Group 1 than those in Group 2 and the control groups (Ach; 40 +/- 20 vs 26 +/- 11, 27 +/- 12%: Erg; 37 +/- 18 vs 12 +/- 8, 13 +/- 10% respectively, P < 0.05). However, the basal coronary artery tone was not elevated at the spastic and nonspastic sites in Group 2 compared to the in control subjects. These findings suggest that the basal coronary artery tone is increased in patients with variant angina with higher disease activity at the spastic sites and nonspastic sites of the spasm-related artery, and this may be related to the occurrence of coronary artery spasm.

Percutaneous transcatheter repair of a coronary aneurysm using a composite autologous cephalic vein-coated Palmaz-Schatz biliary stent

We describe a novel percutaneous transcatheter technique using an autologous vein graft-coated Palmaz-Schatz stent for the treatment of a coronary aneurysm. This technique avoids the procedural risks that are currently associated with surgical repair with revascularization or spring coil embolization in the treatment of coronary aneurysm.

Can coronary flow parameters after stent placement predict restenosis?

Intracoronary stent was used to treat a dissection resulting from balloon angioplasty. Coronary flow parameters measured with Doppler Flowire pre- and post-stenting suggested abnormal coronary flow even after stenting. The patient returned 4 months later with an instent restenosis. This case suggests the intriguing possibility of coronary flow parameters obtained immediately after new device angioplasty in predicting restenosis.

Analysis of 2,2,2-trifluoroethyl derivatives of carboxylic acid herbicides by gas chromatography with mass-selective and electron capture detection

A method for derivatizing carboxylic acid herbicides with 2,2,2-trifluoroethanol (TFE) in preparation for gas chromatographic (GC) analysis was developed. Esterification efficiency was determined by GC with electron capture detection (ECD), and esters were identified by GC with mass-selective detection (MSD). On the basis of reaction temperature for optimum esterification efficiency, 13 common carboxylic acid herbicides were separated into 2 groups before reaction with TFE. TFE derivatization was optimized for simultaneous analyses by altering reaction temperature, re action time, and concentration of sulfuric acid in reaction solutions. The method is simple, safe, and economical, and it gives good resolution without a laborious cleanup. Recovery of 13 analytes from water, taken from a pesticide residue well, was greater than 80% for all except 2 analytes. The well-water was fortified with analytes at the lower microgram-per-liter concentrations required for detection of pesticide residues in potable water systems. The method can simultaneously determine multiple herbicide residues in water samples with a high degree of accuracy and precision.

Vascular effects of diet-induced hypercalcemia after balloon artery injury in giant Flemish rabbits

To determine whether metastatic calcification during neointima formation can result in neointimal calcification that simulates advanced human atherosclerosis, 32 giant Flemish rabbits (weight 5.5 +/- 0.6 kg) underwent overstretch balloon injury of bilateral iliac arteries and received diet therapy for 8 weeks: high cholesterol (2%) and low calcium-vitamin D2 regimen (250 mg of calcium carbonate orally 5 times weekly and 50,000 U of calciferol intramuscularly 3 times weekly; group 1; n = 5); low cholesterol (0.5%) and high calcium-vitamin D2 regimen (500 mg of calcium carbonate orally 5 times weekly and 100,000 U of calciferol intramuscularly three times weekly; group 2; n = 19); or 0% cholesterol and high calcium-vitamin D2 regimen (group 3; n = 8). The incidence of vascular calcification was highest (71.4%) in group 2. Eighty-one percent of calcification was medial. Residual strain measurements of 7 thoracic aortas from group 2 compared to normal thoracic aortas from 8 control rabbits showed that residual strain was significantly increased in the calcified atherosclerotic aortas (12.3% vs 5.2%; p = 0.001). We conclude that diet-induced hypercalcemia predominantly affects the media despite the presence of concomitant neointima formation from balloon artery injury with or without hypercholesterolemia and increases the residual strain more than twofold compared to normal thoracic aortas.

Evidence for apoptosis in human atherogenesis and in a rat vascular injury model

Apoptosis is a physiological cell death process important for normal development and involved in many pathological conditions. In atherosclerosis, pathological accumulation of cells in the intima has been attributed to the migration and proliferation of smooth muscle cells, macrophages, and lymphocytes. In this report, we explored the possibility that apoptosis may also contribute to the pathogenesis of this disease. We examined 35 human atherosclerotic lesion samples and identified a substantial number of cells undergoing apoptosis in 25 of the samples. Furthermore, in a rat vascular injury model, apoptotic cells were specifically identified in the neointima. The presence of apoptotic cells was demonstrated by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling, nuclear staining with propidium iodide, and electron microscopy. Immunostaining with cell-type-specific markers and subsequent terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling analysis on the same sample revealed that the majority of the apoptotic cells were modulated smooth muscle cells as well as macrophages. These results indicate that apoptosis occurs in cells of the injured blood vessel as well as the advanced atherosclerotic lesion and that physiological cell death may have an important role in determining the course of atherogenesis.

A modified directional atherectomy catheter for resection of calcified atherosclerotic plaques

BACKGROUND

The purpose of this study was to determine the feasibility of resecting calcified atherosclerotic plaques in human cadaveric vessels by using a modified directional coronary atherectomy catheter and to correlate these results with bench tests using an in-vitro sea coral model.

METHODS

The conventional directional coronary atherectomy catheter was modified by changing the cutter blade to a tungsten carbide material and by increasing the torsional strength of the drive cable. The performance of the modified directional coronary atherectomy (DCA) catheter was compared with the conventional catheter using a sea coral model to simulate calcified material. Then, 10 human ex-vivo arteries (eight with calcification) were treated with both conventional and modified catheters, and the results studied with intravascular ultrasound and confirmed by histologic examination.

RESULTS

Using the modified directional coronary atherectomy catheter it was possible to perform effective and consistent longitudinal cutting, and to resect a significantly larger amount of coral (1.0 +/- 0.1 mm2 versus 0.2 +/- 0.1 mm2 with conventional cutter, P < 0.0001). In heavily calcified ex-vivo arteries, the modified catheter was more effective in removing calcified plaques (13 +/- 11 mg versus 3.7 +/- 1.4 mg with conventional cutter, P = 0.07). Intravascular ultrasound confirmed the effective atherectomy (residual area stenosis 28 +/- 16% versus 47 +/- 10% with the conventional device, P < 0.05), and histologic examination showed calcified nodules in the atherectomy samples obtained with the modified cutter (area of calcium 1.43 +/- 0.89 mm2 versus 0.93 +/- 0.83 mm2 with the conventional cutter).

CONCLUSIONS

The modified directional coronary atherectomy catheter effectively removed both non-calcified and calcified plaques in the ex-vivo human cadaveric arteries, thus demonstrating the feasibility of directional coronary atherectomy of calcified plaques. This modified device shows promise for treating calcified coronary lesions, especially in larger vessels.

Localized drug delivery in atherosclerotic arteries via a new balloon angioplasty catheter with intramural channels for simultaneous local drug delivery

A dual-purpose angioplasty catheter with intramural channels and exterior pores for local drug delivery ("channeled balloon") was studied in eight atherosclerotic human necropsy arteries and in 22 rabbits with atherosclerotic peripheral arteries, in which markers (0.005 microns to 15 microns) were infused locally at 2 atmospheres during simultaneous angioplasty at 6 atmospheres. Thirteen of the rabbits were sacrificed at 4 or 24 h after procedure to determine the intramural retention over time. Histology confirmed effective angioplasty and revealed presence of markers in the arterial wall in 29 of 43 treated arteries (67%), whereas all control segments without local delivery had no marker staining. majority of the ineffective local delivery (12/14) occurred when 15 micron particles were infused (12/13 arteries without intramural markers), especially when examined 4 or 24 h later. Thus, in atherosclerotic arteries, the channeled balloon enabled simultaneous local drug delivery at low pressure during effective angioplasty, although particle size may play a role in successful intramural impregnation and retention.

Expansion of the Ki-67 proliferative compartment correlates with degree of dysplasia in Barrett's esophagus

BACKGROUND

Barrett's esophagus is a histologically defined premalignant lesion of the esophagus in which normal squamous epithelium is replaced by intestinalized columnar epithelium. In a multistep progression from Barrett's esophagus to fully developed carcinoma, accelerated proliferation may indicate or precede genomic instability and, therefore, may be an important factor in the pathogenesis and/or prediction of malignant transformation. Ki-67 is a nuclear antigen expressed in proliferating cells, (G1, S, G2, and M phases) but not in resting cells (G0 phase). This study was undertaken to determine if Ki-67 expression correlates with the degree of dysplasia and if Ki-67 expression can help to differentiate those patients with or without dysplasia.

METHODS

The Ki-67 proliferation fraction in 87 paraffin embedded esophageal biopsies from 43 patients with the Ki-67 antibody (MIB-1) was analyzed using immunohistochemistry. Using a computerized proliferation index program (QNA v2.54, Becton Dickinson Cellular Imaging Systems, Inc., Elmhurst, IL), a Ki-67 score was derived for the luminal surface, upper esophageal crypt, lower crypt, and underlying glandular zone of the columnar-lined esophagus.

RESULTS

Significant differences in Ki-67 scores were noted in each zone among different histologic categories: normal gastric ([NG] n = 17); Barrett's without dysplasia ([ND] n = 17); low grade dysplasia ([LG] n = 21); high grade dysplasia ([HG] n = 14); and adenocarcinoma ([CA] n = 5). The pattern of Ki-67 expression was associated strongly with each histologic category. The percentage of Ki-67 positive nuclei in each mucosal zone statistically separated high grade from low grade dysplasia (P < 0.001). In high grade dysplastic tissues, the Ki-67 positive nuclei were found predominantly on the surface epithelium and upper crypt zones, whereas in low grade dysplasia, the majority of Ki-67 positive nuclei were found in the lower crypt zone. The number of Ki-67 positive nuclei in each mucosal component also was significantly different in Barrett's esophagus without dysplasia when compared with Barrett's esophagus with low grade dysplastic tissues. (P < 0.001) Staining patterns of indefinite for dysplasia by H & E staining separated into several distinct patterns (five LG, seven ND, one NG) whereas six biopsies with low grade dysplasia had a Ki-67 expression pattern more consistent with that of high grade dysplasia.

CONCLUSION

The Ki-67 staining pattern correlated with histologic findings in Barrett's esophagus and may represent an additional parameter for differentiating patients with or without dysplasia.

Comparison of clinical and angiographic outcomes after saphenous vein graft angioplasty using coronary versus 'biliary' tubular slotted stents

BACKGROUND

Saphenous vein graft (SVG) angioplasty using 15-mm articulated, tubular slotted stents results in low (0% to 20%) residual diameter stenoses and infrequent (< 5%) major complications. A "biliary" stent design with greater radial compressive strength, enhanced visibility, and more variable sizing (diameter and length) has been approved for noncoronary indications. A comparison of outcomes after coronary versus biliary stent placement in SVG stenoses has not been performed. The purpose of this study was to compare the angiographic and clinical results after SVG angioplasty using these two balloon-expandable, tubular slotted stent designs.

METHODS AND RESULTS

During a 3-year period, 231 patients with 305 SVG lesions were treated using Palmaz-Schatz coronary (n = 108) or biliary (n = 123) stents. Cineangiograms were reviewed using qualitative morphological and quantitative angiographic methods. Time-dependent clinical outcome (freedom from death, Q-wave myocardial infarction, or the need for repeat coronary bypass surgery or SVG angioplasty) was assessed using Kaplan-Meier life-table methods. Unstable angina (P < .001) and recent myocardial infarction (P = .001) were present more often in patients undergoing biliary stent versus coronary stent placement. Biliary stent-treated SVG lesions were more frequently de novo (P = .001), ostial in location (P = .002), > or = 10 mm in length (P = .009), thrombus containing (P = .001), and ulcerated (P < .001) than coronary stent-treated SVG lesions. Angiographically, biliary stent-treated lesions had larger reference vessel diameter (3.43 +/- 0.59 mm versus 3.10 +/- 0.64 mm, P < .001), higher balloon-to-artery ratio (1.15 +/- 0.16 mm versus 1.07 +/- 0.19, P = .0001), and lower residual diameter stenosis (6 +/- 17% versus 14 +/- 11% in coronary stent-treated patients; P < .001). Procedural success rates were high (95%), in-hospital major complications were uncommon (< 3%), and follow-up clinical outcomes were favorable (6-month event-free survival approximately 80%) in both groups.

CONCLUSIONS

Despite frequent short-term ischemic syndromes and unfavorable lesion characteristics, both biliary and coronary cohorts have similarly favorable short-term procedural results and long-term clinical outcomes. The increased strut thickness of the biliary stent confers greater fluoroscopic visibility and radial compressive strength in exchange for decreased stent flexibility and added technical demand in stent deployment. Extreme caution is recommended with biliary stent placement in the treatment of SVG lesions as clinical results are highly operator dependent.

Inhibition of platelet deposition and lysis of intracoronary thrombus during balloon angioplasty using urokinase-coated hydrogel balloons

BACKGROUND

Conventional balloon angioplasty of intracoronary thrombus is associated with a high incidence of abrupt closure, distal embolization, and no-reflow phenomenon. The purpose of this study was to assess a new technique for treating intracoronary thrombus consisting of the local delivery of urokinase directly to the angioplasty site with urokinase-coated hydrogel balloons.

METHODS AND RESULTS

We assessed local urokinase delivery using hydrogel balloons in four protocols. First, we evaluated the pharmacokinetics of urokinase delivery in vitro using 125I-labeled urokinase to measure drug loading onto hydrogel balloons, drug retention by the hydrogel polymer during blood exposure, and drug transfer from the balloon surface to the arterial wall during balloon dilatation. Second, we measured 125I-urokinase washoff from the hydrogel balloon in the intact circulation and intramural drug delivery during in vivo balloon angioplasty in 10 anesthetized New Zealand rabbits. Third, we assessed the effect of local urokinase delivery on 111In-labeled platelet deposition after balloon angioplasty in vivo in 13 porcine carotid or iliac arteries dilated with urokinase-coated balloons and compared them with contralateral control arteries dilated with saline-coated balloons. Finally, we determined the clinical efficacy of urokinase-coated balloons in 15 patients with intracoronary thrombus, including 7 who demonstrated abrupt thrombotic closure after conventional angioplasty. Between 241 and 1509 U urokinase could be loaded onto hydrogel balloons ranging in size from 2 to 8 mm. In vitro and in vivo studies demonstrated that hydrogel balloons absorbed significantly more urokinase and demonstrated less drug wash-off than nonhydrogel balloons (P < .01). Similarly, both in vitro and in vivo studies demonstrated urokinase transfer from the hydrogel to the arterial wall during balloon angioplasty, with greater intramural drug deposition with larger balloons (P < .01). Local urokinase delivery after in vivo porcine angioplasty decreased 111In-labeled platelet deposition by 47% compared with contralateral control vessels (P = .03). Use of urokinase-coated balloons in patients with intracoronary thrombus resulted in thrombus dissolution and reversal of abrupt closure in all cases, without evidence of distal embolization.

CONCLUSIONS

With the use of hydrogel-coated balloons, urokinase can be delivered locally to an angioplasty site. This technique decreases platelet deposition after in vivo balloon angioplasty and is efficacious in treating intracoronary thrombus in patients, including those with abrupt thrombotic closure.

Limitations of angiography for analyzing coronary atherosclerosis progression or regression

PURPOSE

To analyze the utility and limitations of serial coronary angiography for determining atherosclerosis progression and regression.

DATA SOURCES

A MEDLINE search of the English-language literature (1966 to January 1994) using the keywords atherosclerosis regression, atherosclerosis progression, lipid reduction therapy, and coronary angiography.

STUDY SELECTION

Selected articles on the effects of cholesterol reduction and lifestyle modification on angiographic coronary artery disease, on the animal models of atherosclerosis progression and regression, and on the limitations of coronary angiography.

DATA EXTRACTION

Independent extraction by two authors.

RESULTS

Although several studies have reported that the rate of atherosclerosis progression, defined by serial coronary angiography, can be reduced and that luminal diameter can be improved somewhat by aggressive lipid modification, the reported changes are small (0.3 mm or 10% change) and have required a prolonged study duration (range, 1 to 10 years). More importantly, angiography simply does not measure atherosclerosis and cannot assess lesion composition. Angiography also underestimates the extent of atherosclerosis, especially in angiographically normal segments. In addition, difficulties with data acquisition, such as substantial variabilities in serial measurements of percent diameter stenosis and minimal luminal diameters, require large sample sizes to show statistically significant regression, even with computerized quantification.

CONCLUSIONS

Given its current limitations, serial coronary angiography is not a satisfactory means of detecting atherosclerosis progression or regression.

Acute myocardial infarction in the young adults

A review was done on 631 patients with acute myocardial infarction who underwent coronary angiography within 30 days after onset of myocardial infarction at Yonsei University Severance Hospital from January, 1985, to August, 1993. The incidence of acute myocardial infarction in patients under 40 years of age was 10.3% (65/631). Acute myocardial infarction below the fourth decades was the predominant disease of men. Risk factor analysis revealed a history of cigarette smoking and hypercholesterolemia were more frequently found in the young patients, but a history of hypertension and diabetes were more frequently found in the elderly patients. Angiographically, the incidence of one vessel disease and normal or minimal lesion coronary anatomy were more frequent in the young patients and incidence of multi-vessel disease were more frequent in the elderly patients. Of the 65 patients under 40 with acute myocardial infarction, the patients with multi-vessel disease tended to have a history of diabetes mellitus in comparison with those with normal coronary anatomy or one vessel disease.

Clinical significance of distal embolization after transluminal extraction atherectomy in diffusely diseased saphenous vein grafts

Standard balloon angioplasty of degenerated saphenous vein graft lesions may be complicated by distal embolization, particularly in the presence of intragraft thrombus. Transluminal extraction atherectomy may be useful in this setting because of its ability to remove particulate debris. This study was designed to identify the incidence and prognostic significance of distal embolization after transluminal extraction atherectomy in high-risk saphenous vein graft lesions. To address these issues the clinical course of 65 consecutive patients (86 high-risk saphenous vein graft lesions) was reviewed after extraction atherectomy. Distal embolization occurred in 11 (12.8%) of 86 high-risk lesions. The majority (63.6%) of these episodes occurred after adjunct balloon dilatation following uncomplicated use of the extraction atherectomy catheter. Correlates of distal embolization included patient age and the presence of intragraft thrombus. Major in-hospital complications developed more often in patients with distal embolization (46% vs 2% in those without distal embolization, p < 0.001), resulting in a reduced procedural success rate in this group (55% vs 91%, p = 0.01). We conclude that the risk of distal embolization after saphenous vein graft angioplasty, although potentially reduced, is not eliminated with transluminal extraction atherectomy, particularly in lesions with superimposed thrombus.

A dual-purpose angioplasty-drug infusion catheter for the treatment of intragraft thrombus

An investigational angioplasty-drug infusion catheter (Transport, CardioVascular Dynamics, Irvine, CA) was used to treat a saphenous vein graft stenosis associated with a thrombus. The catheter was successfully used both to infuse urokinase at the site of angioplasty and to perform effective angioplasty, demonstrating the feasibility and utility of a dual-purpose angioplasty catheter capable of angioplasty and/or local drug infusion with the same catheter.

Feasibility and drug delivery efficiency of a new balloon angioplasty catheter capable of performing simultaneous local drug delivery

BACKGROUND

Local drug delivery at angioplasty treatment sites may improve acute and long-term results after angioplasty. A new dual-purpose balloon angioplasty catheter containing intramural channels and exterior pores ('channeled balloon') was designed to allow local drug delivery at low pressure without jet streams during simultaneous balloon angioplasty.

METHODS

Acute feasibility studies were performed in normal ex-vivo and in-vivo arteries (three canine arteries and three rabbits with normal iliac arteries), in which 2 ml of marker agents were locally infused at 2 atm during simultaneous angioplasty at 6 atm with the channeled balloon. Histology, radioactive counting, and autoradiography were performed to determine the intramural localization of the delivered markers. The in-vitro efficiency of acute local drug delivery was estimated in seven normal canine arteries by infusing 3H-heparin and radioactive counting.

RESULTS

Histology revealed the presence of markers in the inner third of the media in all ex-vivo samples, and markers in all in-vivo iliac arteries except for one, whereas control segments had no intramural staining. Autoradiography documented transmural radioactive granules. Radioactive counts were 40- to 263-fold higher in those locally treated with the radioactive marker agent. Efficiency of the acute local delivery was estimated by dividing the actual counts by the expected counts; it ranged from 24 to 48%.

CONCLUSION

This study demonstrates that the channeled balloon is capable of delivering drugs locally at low pressure in adequate concentrations during simultaneous high-pressure balloon angioplasty in normal arteries.

The effect of porous infusion balloon-delivered angiopeptin on myointimal hyperplasia after balloon injury in the rabbit

BACKGROUND

Angiopeptin, a synthetic somatostatin analogue, reduces myointimal hyperplasia after experimental balloon angioplasty when given subcutaneously. The feasibility and efficacy of a single dose of angiopeptin delivered locally via the Wolinsky porous balloon on myointimal hyperplasia were studied.

METHODS AND RESULTS

Three rabbits received 125I-angiopeptin in the mid abdominal aorta via the Wolinsky balloon at 5 atm for 1 minute after balloon injury. Thirty minutes later, autoradiography demonstrated radioactivity in the media and the adventitia. Forty rabbits were divided equally into one control group receiving saline and three angiopeptin groups receiving 1, 10, or 100 micrograms/mL of angiopeptin delivered locally at 5 atm for 1 minute via the Wolinsky balloon into the mid abdominal aorta after balloon injury of the entire abdominal aorta. On day 21, the abdominal aortas were fixed in situ and harvested. There was no statistical difference in the amount of myointimal hyperplasia in the locally treated aorta in the angiopeptin groups compared with the control group. However, in the lower abdominal aorta, where balloon injury without local delivery was performed, there was a significant reduction of myointimal hyperplasia in the highest-concentration angiopeptin group (P < .001 versus the control group). Electron microscopy showed that the control animals had a pseudointima of smooth muscle cells throughout the aorta, whereas in all the angiopeptin-treated animals, endothelial cells were present at both locations.

CONCLUSIONS

Angiopeptin can be delivered intramurally via the Wolinsky porous balloon and reduces myointimal hyperplasia only in the area distal to the local drug delivery site (downstream effect), possibly by healing the injured endothelium, by transport via the vasa vasora, and/or by systemic effect.

Effects of estrogen replacement therapy on serum lipid values and angiographically defined coronary artery disease in postmenopausal women

To examine the effects of estrogen replacement on lipids and angiographically defined coronary artery disease (CAD) in postmenopausal women, lipid profiles were obtained in 90 consecutive postmenopausal women undergoing diagnostic coronary angiography. Eighteen women (20%) were receiving estrogen and 72 (80%) were not. CAD (defined as greater than or equal to 25% luminal diameter narrowing in a major coronary artery) was present in only 22% of women (4 of 18) receiving estrogen and in 68% (49 of 72) who were not (p less than 0.001), with an odds ratio of 0.13. Mean high-density lipoprotein (HDL) cholesterol level was significantly higher (63 +/- 6 vs 48 +/- 2; p less than 0.01) and mean total/HDL cholesterol ratio significantly lower in women receiving estrogen than in those who were not (4.2 +/- 0.5 vs 5.1 +/- 0.2; p less than 0.05). The other lipid values were similar in both groups. On multiple logistic regression analysis, absence of estrogen use was the most powerful independent predictor of the presence of CAD (p less than 0.001), with total/HDL cholesterol ratio as the only other variable selected (p less than 0.01). Thus, among 90 consecutive postmenopausal women undergoing diagnostic coronary angiography, estrogen replacement therapy was associated with an 87% reduction in the prevalence of CAD, and those receiving estrogen had a significantly higher mean HDL cholesterol level and lower mean total/HDL cholesterol ratio.

Usefulness of the total cholesterol to high-density lipoprotein cholesterol ratio in predicting angiographic coronary artery disease in women

To investigate the relation between lipids and angiographic coronary artery disease (CAD) in women, fasting lipid profiles were obtained on 108 women undergoing coronary angiography (group I). CAD, defined as greater than or equal to 25% luminal diameter narrowing in a major coronary artery, was present in 57 (53%). Neither serum total cholesterol nor triglyceride levels correlated with the presence of CAD. Mean total/high-density lipoprotein (HDL) cholesterol ratio was higher among women with than without CAD (5.5 +/- 0.3 vs 4.2 +/- 0.2, p less than 0.0001). Multiple regression analyses identified a higher total/HDL cholesterol ratio as the variable most predictive of the presence (p less than 0.001), extent (number of narrowed arteries) (p less than 0.0001), and severity (% maximum stenosis) (p less than 0.001) of CAD. Age and lack of estrogen use were also independently associated with the presence of CAD, age and low-density lipoprotein cholesterol level were additional indicators of extent, and age was the only other discriminator of severity of CAD. In 56 women with total cholesterol less than 200 mg/dl (group II), mean total/HDL cholesterol ratio was higher in women with (n = 24) than without CAD (4.3 +/- 0.2 vs 3.5 +/- 0.2, p = 0.01). Higher total/HDL cholesterol ratio was the variable most predictive of the presence of CAD (p = 0.01), and the lone variable associated with severity (p less than 0.001) after adjustment for other risk factors. Age was independently associated with presence and extent, and hypertension was also independently related to extent.(ABSTRACT TRUNCATED AT 250 WORDS)

Conformational substates and motions in myoglobin. External influences on structure and dynamics

Myoglobin, a simppe dioxygen-storage protein, is a good laboratory for the investigation of the connection between protein structure, dynamics, and function. Fourier-transform infrared spectroscopy on carbon-monoxymyoglobin (MbCO) shows three major CO bands. These bands are excellent probes for the investigation of the structure-function relationship. They have different CO binding kinetics and their CO dipoles form different angles with respect to the heme normal, implying that MbCO exists in three major conformational substates, A0, A1, and A3. The entropies and enthalpies of these substates depend on temperature above approximately 180 K and are influenced by pH, solvent, and pressure. These results suggest that even a protein as simple as Mb can assume a small number of clearly different structures that perform the same function, but with different rates. Moreover, protein structure and dynamics depend strongly on the interaction of the protein with its environment.

Inhomogeneous broadening in spectral bands of carbonmonoxymyoglobin. The connection between spectral and functional heterogeneity

The rebinding kinetics of CO to myoglobin after flash photolysis is nonexponential in time below approximately 180 K; the kinetics is governed by a distribution of enthalpic barriers. This distribution results from inhomogeneities in the protein conformation, referred to as conformational substates. Hole-burning experiments on the Soret and IR CO-stretch bands test the assumption that an inhomogeneous distribution of conformational substates results in inhomogeneously broadened spectra. CO was slowly photolyzed at different wavelengths in the Soret band at 10 K. Both the Soret band and the CO-stretch band A1, centered at 1,945 cm-1, shift during photolysis, demonstrating that different wavelengths excite different parts of the distributed population. We have also done kinetic hole-burning experiments by measuring peak shifts in the Soret and A1 bands as the CO molecules rebind. The shifts indicate that the spectral and enthalpic distributions are correlated. In the A1 band, the spectral and enthalpic distributions are highly correlated while in the Soret the correlation is weak. From the peak shifts in the spectral and kinetic hole-burning experiments the inhomogeneous broadening is estimated to be approximately 15% of the total width in the Soret band and approximately 60% in A1. We have previously measured the tilt angle alpha between the bound CO and the heme normal (Ormos, P., D. Braunstein, H. Frauenfelder, M. K. Hong, S.-L. Lin, T. B. Sauke, and R. D. Young. 1988. Proc. Natl. Acad. Sci. USA. 85:8492-8496) and observed a wave number dependence of the tilt angles within the CO-stretch A bands. Thus the spectral and enthalpic distributions of the A bands are coupled to a heterogeneity of the structure.