Sterol 27-hydroxylase acts on 7-ketocholesterol in human atherosclerotic lesions and macrophages in culture

27-Hydroxycholesterol (27OH) is the major oxysterol in human atherosclerotic lesions, followed by 7-ketocholesterol (7K). Whereas 7K probably originates nonenzymically, 27OH arises by the action of sterol 27-hydroxylase, a cytochrome P450 enzyme expressed at particularly high levels in the macrophage and proposed to represent an important pathway by which macrophages eliminate excess cholesterol. We hypothesized and here show that 27-hydroxylated 7-ketocholesterol (270H-7K) is present in human lesions, probably generated by the action of sterol 27-hydroxylase on 7K. Moreover, [(3)H]27OH-7K was produced by human monocyte-derived macrophages (HMDMs) supplied with [(3)H]7K but not in HMDMs from a patient with cerebrotendinous xanthomatosis (CTX) shown to have a splice-junction mutation of sterol 27-hydroxylase. Whereas [(3)H]27OH-7K was predominantly secreted into the medium, [(3)H]-27OH formed from [(3)H]-cholesterol was mostly cell-associated. The majority of supplied [(3)H]7K was metabolized beyond 27OH-7K to aqueous-soluble products (apparently bile acids derived from the sterol 27-hydroxylase pathway). Metabolism to aqueous-soluble products was ablated by a sterol 27-hydroxylase inhibitor and absent in CTX cells. Sterol 27-hydroxylase therefore appears to represent an important pathway by which macrophages eliminate not only cholesterol but also oxysterols such as 7K. The fact that 7K (and cholesterol) still accumulates in lesions and foam cells indicates that this pathway may be perturbed in atherosclerosis and affords a new opportunity for the development of therapeutic strategies to regress atherosclerotic lesions.

Common and rare ABCA1 variants affecting plasma HDL cholesterol

Mutations in ABCA1, a member of the ATP-binding cassette family, have been shown to underlie Tangier disease (TD) and familial hypoalphalipoproteinemia (FHA), which are genetic disorders that are characterized by depressed concentrations of plasma high density lipoprotein (HDL) cholesterol. An important question is whether common variants within the coding sequence of ABCA1 can affect plasma HDL cholesterol in the general population. To address this issue, we developed a screening strategy to find common ABCA1 variants. This strategy involved long-range amplification of genomic DNA by using coding sequences only, followed by deep sequencing into the introns. This method helped us to characterize a new set of amplification primers, which permitted amplification of virtually all of the coding sequence of ABCA1 and its intron-exon boundaries with a single DNA amplification program. With these new sequencing primers, we found 3 novel ABCA1 mutations: a frameshift mutation (4570insA, A1484S-->X1492), a missense mutation (A986D) in a TD family, and a missense mutation (R170C) in aboriginal subjects with FHA. We also used these sequencing primers to characterize 4 novel common amino acid variants in ABCA1, in addition to 5 novel common silent variants. We tested for association of the ABCA1 I/M823 variant with plasma HDL cholesterol in Canadian Inuit and found that M823/M823 homozygotes had significantly higher plasma HDL cholesterol compared with subjects with the other genotypes. The results provide proof of principle of the effectiveness of this approach to identify both rare and common ABCA1 genomic variants and also suggest that common amino acid variation in ABCA1 is a determinant of plasma HDL cholesterol in the general population.

The magnitude of decrease in hepatic very low density lipoprotein apolipoprotein B secretion is determined by the extent of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibition in miniature pigs

It has been postulated that the rate of hepatic very low density lipoprotein (VLDL) apolipoprotein (apo) B secretion is dependent upon the activity of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase. To test this hypothesis in vivo, apoB kinetic studies were carried out in miniature pigs before and after 21 days treatment with high-dose (10 mg/kg/day), atorvastatin (A) or simvastatin (S) (n = 5). Pigs were fed a diet containing fat (34% of calories) and cholesterol (400 mg/day; 0.1%). Statin treatment decreased plasma total cholesterol [31 (A) vs. 20% (S)] and low density lipoprotein (LDL) cholesterol concentrations [42 (A) vs. 24% (S)]. Significant reductions in plasma total triglyceride (46%) and VLDL triglyceride (50%) concentrations were only observed with (A). Autologous [131I]VLDL, [125I]LDL, and [3H]leucine were injected simultaneously, and apoB kinetic parameters were determined by triple-isotope multicompartmental analysis using SAAM II. Statin treatment decreased the VLDL apoB pool size [49 (A) vs. 24% (S)] and the hepatic VLDL apoB secretion rate [50 (A) vs. 33% (S)], with no change in the fractional catabolic rate (FCR). LDL apoB pool size decreased [39 (A) vs. 26% (S)], due to reductions in both the total LDL apoB production rate [30 (A) vs. 21% (S)] and LDL direct synthesis [32 (A) vs. 23% (S)]. A significant increase in the LDL apoB FCR (15%) was only seen with (A). Neither plasma VLDL nor LDL lipoprotein compositions were significantly altered. Hepatic HMG-CoA reductase was inhibited to a greater extent with (A), when compared with (S), as evidenced by 1) a greater induction in hepatic mRNA abundances for HMG-CoA reductase (105%) and the LDL receptor (40%) (both P < 0.05); and 2) a greater decrease in hepatic free (9%) and esterified cholesterol (25%) (both P < 0.05). We conclude that both (A) and (S) decrease hepatic VLDL apoB secretion, in vivo, but that the magnitude is determined by the extent of HMG-CoA reductase inhibition.

Acyl coenzyme A: cholesterol acyltransferase inhibition and hepatic apolipoprotein B secretion

Acyl coenzyme A: cholesterol acyltransferase (ACAT) is postulated to play a role in hepatic and intestinal lipoprotein secretion. There is accumulating evidence, both in vitro and in vivo, that cholesterol and/or cholesteryl ester availability can regulate hepatic VLDL secretion. How ACAT inhibition regulates the assembly and secretion of apolipoprotein (apo) B containing lipoproteins within the hepatocyte has not been clearly established. ApoB kinetic studies performed in animals indicate that reduction in VLDL apoB secretion is an important mechanism whereby ACAT inhibitors decrease the plasma concentrations of these lipoproteins. However, in cultured hepatocytes, the effect of ACAT inhibition on apoB secretion has been inconsistent. Recent evidence has suggested the existence of more than one ACAT enzyme in mammals, which has culminated in the recent cloning of ACAT2. ACAT1 and ACAT2 respond differently to ACAT inhibitors of differing structures and classes. ACAT2 is present in the liver and intestine, the sites of apoB containing lipoprotein secretion and may represent the enzyme responsible for generating cholesteryl esters destined for lipoprotein assembly and secretion.

Inhibition of ACAT by avasimibe decreases both VLDL and LDL apolipoprotein B production in miniature pigs

An orally bioavailable acyl coenzyme A:cholesterol acyltransferase (ACAT) inhibitor, avasimibe (CI-1011), was used to test the hypothesis that inhibition of cholesterol esterification, in vivo, would reduce hepatic very low density (VLDL) apolipoprotein (apo) B secretion into plasma. ApoB kinetic studies were carried out in 10 control miniature pigs, and in 10 animals treated with avasimibe (10 mg/kg/d, n = 6; 25 mg/kg/d, n = 4). Pigs were fed a diet containing fat (34% of calories) and cholesterol (400 mg/d; 0.1%). Avasimibe decreased the plasma concentrations of total triglyceride, VLDL triglyceride, and VLDL cholesterol by 31;-40% 39-48%, and 31;-35%, respectively. Significant reductions in plasma total cholesterol (35%) and low density lipoprotein (LDL) cholesterol (51%) concentrations were observed only with high dose avasimibe. Autologous 131I-labeled VLDL, 125I-labeled LDL, and [3H]leucine were injected simultaneously into each pig and apoB kinetic data were analyzed using multicompartmental analysis (SAAM II). Avasimibe decreased the VLDL apoB pool size by 40;-43% and the hepatic secretion rate of VLDL apoB by 38;-41%, but did not alter its fractional catabolism. Avasimibe decreased the LDL apoB pool size by 13;-57%, largely due to a dose-dependent 25;-63% in the LDL apoB production rate. Hepatic LDL receptor mRNA abundances were unchanged, consistent with a marginal decrease in LDL apoB FCRs. Hepatic ACAT activity was decreased by 51% (P = 0.050) and 68% (P = 0.087) by low and high dose avasimibe, respectively. The decrease in total apoB secretion correlated with the decrease in hepatic ACAT activity (r = 0.495; P = 0.026). We conclude that inhibition of hepatic ACAT by avasimibe reduces both plasma VLDL and LDL apoB concentrations, primarily by decreasing apoB secretion.

The HMG-CoA reductase inhibitor atorvastatin increases the fractional clearance rate of postprandial triglyceride-rich lipoproteins in miniature pigs

We have previously shown in vivo that the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor atorvastatin decreases hepatic apolipoprotein B (apoB) secretion into plasma. To test the hypothesis that atorvastatin modulates exogenous triglyceride-rich lipoprotein (TRL) metabolism in vivo, an oral fat load (2 g fat/kg body wt) containing retinol (50 000 IU) was given to 6 control miniature pigs and to 6 animals after 28 days of treatment with atorvastatin 3 mg. kg-1. d-1. A multicompartmental model was developed by use of SAAM II and kinetic analysis performed on the plasma retinyl palmitate (RP) data. Peak TRL (d<1.006 g/mL; Sf>20) triglyceride concentrations were decreased 29% by atorvastatin, and the time to achieve this peak was delayed (5.2 versus 2.3 hours; P<0.01). The TRL triglyceride 0- to 12-hour area under the curve was decreased by 24%. In contrast, atorvastatin treatment had no effect on peak TRL RP concentrations, time to peak, or its rate of appearance into plasma; however, the TRL RP 0- to 12-hour area under the curve was decreased by 20%. Analysis of the RP kinetic parameters revealed that the TRL fractional clearance rate was increased significantly, 1.4-fold (3.093 versus 2.276 pools/h; P=0.012), with atorvastatin treatment. The percent conversion of TRL RP from the rapid-turnover to the slow-turnover compartment was decreased by 47% with atorvastatin treatment. The TRL RP fractional clearance rate was negatively correlated with very low density lipoprotein apoB production rate measured in the fasting state (r=-0.49). Thus, although atorvastatin had no effect on intestinal TRL assembly and secretion, plasma TRL clearance was significantly increased, an effect that may relate to a decreased competition for removal processes by hepatic very low density lipoprotein.

Inhibition of cholesterol esterification by DuP 128 decreases hepatic apolipoprotein B secretion in vivo: effect of dietary fat and cholesterol

To further test the hypothesis that newly synthesized cholesteryl esters regulate hepatic apolipoprotein B (apoB) secretion into plasma, apoB kinetic studies were carried out in seven control miniature pigs and in seven animals after 21 days intravenous administration of the acyl coenzyme A:cholesterol acyltransferase (ACAT) inhibitor DuP 128 (2.2 mg/kg/day). Pigs were fed a fat (34% of calories; polyunsaturated/monounsaturated/saturated ratio, 1:1:1) and cholesterol (400 mg/day; 0.1%; 0.2 mg/kcal) containing pig chow based diet. DuP 128 significantly reduced total plasma triglyceride and very low density lipoprotein (VLDL) triglyceride concentrations by 36 and 31%, respectively (P<0.05). Autologous 131I-VLDL and 125I-LDL were injected simultaneously into each pig and apoB kinetic data was analyzed using multicompartmental analysis (SAAM II). The VLDL apoB pool size decreased by 26% (0.443 vs. 0.599 mg/kg; P<0. 001) which was due entirely to a 28% reduction in VLDL apoB production or secretion rate (1.831 vs. 2.548 mg/kg/h; P=0.006). The fractional catabolic rate (FCR) for VLDL apoB was unchanged. The LDL apoB pool size and production rate were unaffected by DuP 128 treatment. Hepatic microsomal ACAT activity decreased by 51% (0.44 vs. 0.90 nmol/min/mg; P<0.001). Although an increase in hepatic free cholesterol and subsequent decrease in both LDL receptor expression and LDL apoB FCR might be expected, this did not occur. The concentration of hepatic free cholesterol decreased 12% (P=0.008) and the LDL apoB FCR were unaffected by DuP 128 treatment. In addition, DuP 128 treatment did not alter the concentration of hepatic triglyceride or the activity of diacylglycerol acyltransferase, indicating a lack of effect of DuP 128 on hepatic triglyceride metabolism. In our previous studies, DuP 128 treatment of miniature pigs fed a low fat, cholesterol free diet, decreased VLDL apoB secretion by 65% resulting in a reduction in plasma apoB of 60%. We conclude that in miniature pigs fed a high fat, cholesterol containing diet, the inhibition of hepatic cholesteryl ester synthesis by DuP 128 decreases apoB secretion into plasma, but the effect is attenuated relative to a low fat, cholesterol free diet.

Inhibition of HMG-CoA reductase by atorvastatin decreases both VLDL and LDL apolipoprotein B production in miniature pigs

In the present studies, the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor atorvastatin was used to test the hypothesis that inhibition of cholesterol biosynthesis in vivo with a consequent reduction in the availability of hepatic cholesterol for lipoprotein synthesis, would (1) reduce very low density lipoprotein (VLDL) apolipoprotein B (apoB) secretion into the plasma, (2) reduce the conversion of VLDL apoB to LDL apoB, and (3) reduce LDL apoB direct synthesis. ApoB kinetic studies were carried out in six control miniature pigs and in six animals after 21 days of administration of atorvastatin (3 mg/kg per day). Pigs were fed a fat- (34% of calories; polyunsaturated to monounsaturated to saturated ratio, 1:1:1) and cholesterol- (400 mg/d cholesterol; 0.1%; 0.2 mg/kcal) containing pig chow-based diet. Atorvastatin treatment significantly reduced plasma total cholesterol, LDL cholesterol, total triglyceride, and VLDL triglyceride concentrations by 16%, 31%, 19%, and 28%, respectively (P < .01). Autologous 131I-VLDL, 125I-LDL, and [3H]leucine were injected simultaneously into each pig, and apoB kinetic data were analyzed using multicompartmental analysis (SAAM II). The VLDL apoB pool size decreased by 29% (0.46 versus 0.65 mg/kg; P = .002), which was entirely due to a 34% reduction in the VLDL apoB production rate (PR) (1.43 versus 2.19 mg/kg per hour; P = .027). The fractional catabolic rate (FCR) was unchanged. The LDL apoB pool size decreased by 30% (4.74 versus 6.75 mg/kg; P = .0004), which was due to a 22% reduction in the LDL apoB PR (0.236 versus 0.301 mg/kg per hour; P = .004), since the FCR was unchanged. The reduction in LDL apoB PR was primarily due to a 34% decrease in conversion of VLDL apoB to LDL apoB; however, this reduction was not statistically significant (P = .114). Hepatic apoB mRNA abundance quantitated by RNase protection assay was decreased by 13% in the atorvastatin-treated animals (P = .003). Hepatic and intestinal LDL receptor mRNA abundances were not affected. We conclude that inhibition of hepatic HMG-CoA reductase by atorvastatin reduces both VLDL and LDL apoB concentrations, primarily by decreasing apoB secretion into the plasma and not by an increase in hepatic LDL receptor expression. This decrease in apoB secretion may, in part, be due to a reduction in apoB mRNA abundance.

3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors and hepatic apolipoprotein B secretion

Important advances in our understanding of the regulation of hepatic apolipoprotein B secretion have been made in the past year. A diverse group of studies have provided evidence that the inhibition of cholesterol synthesis by 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors decreases the hepatic assembly and secretion of apolipoprotein B-containing lipoproteins. Apolipoprotein B kinetic studies performed in animals and human individuals indicate that inhibition of VLDL-apolipoprotein B secretion is an important mechanism whereby reductase inhibitors decrease plasma concentrations of these lipoproteins. Studies in cultured hepatocytes and in-vivo animal models have provided insights into how reduction of cholesterol synthesis decreases apolipoprotein B secretion. A decrease in hepatic acyl-coenzyme A: cholesterol acyltransferase activity, secondary to reduced microsomal cholesterol concentrations, has been implicated.

A method for the separation of delta bilirubin using Cibacron Blue affinity chromatography

We developed and evaluated a method for the separation of delta bilirubin (B delta) by micro-column affinity chromatography based on Cibacron Blue 3G-A-Agarose. Untreated serum was applied to affinity columns and free non-protein bound bilirubins were eluted with phosphate buffer containing 20 g/l Triton X-100. Retained albumin was eluted using caffeine-benzoate reagent and bilirubin associated with this fraction (B delta) quantitated by the method of Jendrassik and Gróf modified by Doumas et al (Clin Chem 1985;31:1779-1789); results correlated well with the high performance liquid chromatography (HPLC) method (n = 35, y (affinity) = 1.009x (HPLC)-5.49; r = 0.959) described by Lauff et al. (J Chromatography 1981;226:391-402). Two controls analyzed with each batch gave between-batch imprecision less than 4.0% (n = 10; Control 1, mean = 20.05 mumol/l; Control 2, mean = 74.82 mumol/l). Within-batch imprecision was less than 3.3% for both levels. Specimens collected from 25 neonates less than 20 days of age showed a B delta concentration of 1.7 +/- 0.7 mumol/l (mean +/- 1 S.D.) and percent B delta of 2.2 +/- 1.9 (mean total bilirubin +/- 1 S.D. = 118 +/- 79 mumol/l). Although time consuming, this simple and precise method allows the measurement of B delta in laboratories without the need for specialized instruments.

Serum enzymes in hypothyroidism

AIM

To report three cases of hypothyroidism detected because of unexplained elevation of serum enzyme levels on biochemical testing.

METHODS

Clinical details and serum enzyme results were obtained before and after L-thyroxine (T4) replacement therapy.

RESULTS

The three patients all had serum creatine kinase (CK) levels > 2000 U/L, aspartate aminotransferase (AST) > 90 U/L, and lactate dehydrogenase (LD) > 300 U/L at presentation, with these levels being 10-15, 2-6, and 2-3 times the upper reference limits respectively. CK isoenzyme determination was consistent with skeletal muscle origin. Thyroid function tests performed after consultation with the clinical biochemist confirmed the biochemical diagnosis of primary hypothyroidism. A rapid fall toward normal serum enzyme levels occurred in response to T4 replacement therapy.

CONCLUSIONS

Although serum enzymes are an integral part of both the liver and cardiac profiles provided by laboratory, they are not organ specific, and changes may reflect dysfunction elsewhere in the body. Elevations of serum CK (and other muscle enzymes) may occur in hypothyroid subjects, the cause of which has not been established. The clinical diagnosis of hypothyroidism requires a high index of suspicion and should be considered in patients with unexplained persistent elevations of serum muscle enzymes.

Familial hypobetalipoproteinaemia: a rare presentation to the lipid clinic

OBJECTIVE

To report a case of familial hypobetalipoproteinaemia in a woman who presented after the incidental finding of marked hypocholesterolaemia during laboratory tests.

CLINICAL FEATURES

An asymptomatic 37-year-old Lebanese woman presented to the lipid clinic with a serum total cholesterol concentration of 1.1 mmol/L, high density lipoprotein (HDL) cholesterol of 1.0 mmol/L, and triglycerides of 0.28 mmol/L. No secondary cause for the hypocholesterolaemia was established. INVESTIGATION AND OUTCOME: Her serum apolipoprotein B (apo B) levels were markedly reduced at 0.07 g/L. Except for one daughter (IV-4), all other family members including her husband (her first cousin) had apo B levels about 25% of normal. Daughter IV-4 had undetectable apo B levels. Family studies confirmed an autosomal dominant pattern of inheritance consistent with familial hypobetalipoproteinaemia.

CONCLUSION

Familial hypobetalipoproteinaemia is a rare condition that should be considered in the differential diagnosis of hypocholesterolaemia. Absence of clinical features, autosomal dominant pattern of inheritance, and reduced apo B levels suggest the diagnosis.

A study of L-thyroxine replacement

We studied consecutive requests for in vitro thyroid function tests on patients receiving L-thyroxine (T4) for primary hypothyroidism for a three month period May to July 1990, and waited a further three months before ascertaining any changes made to the daily dose of T4. Serum sensitive TSH (sTSH) concentrations were normalised in only 43% of patients treated by a hospital general physician, 50% of patients treated by a specialist endocrinologist and 52% of patients treated by their primary care physician. The respective figures for elevated serum sTSH concentrations were 43%, 33% and 32% and for suppressed levels 15%, 17% and 15%. The dose of T4 required to normalise serum sTSH levels was approximately 110 micrograms/d. In 36% of those patients with suppressed serum sTSH levels the daily dose of thyroxine was reduced. This achieved a mean reduction in the daily dose of 20 micrograms. In 30% of those with raised serum sTSH levels the daily dose of thyroxine was increased. This achieved a mean increase in the daily dose of 15 micrograms. Patients receiving T4 may have raised serum free T4 (fT4) despite normal sTSH levels indicating that serum fT4 measurement is not the test of choice for screening for adequacy of T4 replacement.

Inhibition of human endothelial prostacyclin synthesis by different aspirin formulations

The availability of different formulations of low-dose aspirin for use as anti-thrombotic agents merits a comparison of their effects on vessel wall biochemistry. We compared the effect of ingestion of an enteric-coated slow-release aspirin (Astrix) with that of soluble aspirin (Cardiprin) on human endothelial prostacyclin synthesis. Patients undergoing varicose vein surgery (10 per group) ingested 100 mg aspirin per day as Astrix or Cardiprin for 7 days prior to surgery. A control group ingested no aspirin. Prostacyclin synthesis by the endothelial surface of the great saphenous vein was determined in vitro. Both aspirin formulations caused significant inhibition of endothelial prostacyclin synthesis compared with the control group. Using the median values, the enteric-coated slow-release aspirin caused 76% inhibition, whereas the soluble formulation caused significantly greater inhibition (95%). If differential inhibition of platelet thromboxane synthesis with 'sparing' of endothelial prostacyclin synthesis is necessary for an optimum anti-thrombotic effect of aspirin, the results suggest that a lower dose of soluble aspirin than enteric-coated slow-release aspirin may be preferred.

Internal carotid artery occlusion: effect of contralateral flow reduction in inducing symptoms

Cerebral ischemic attacks ipsilateral to an occluded internal carotid artery (ICA) continue in more than 16% of patients. With common carotid artery compression on the side of ICA occlusion in 53 patients, the mean (+/- SEM) ophthalmic systolic pressure/brachial systolic pressure (OSP/BSP) ratio fell from 0.58 +/- 0.013 to 0.42 +/- 0.020 (p less than 0.001), without any cerebral ischemic symptoms. Compression of the contralateral patent common carotid artery resulted in the ophthalmic systolic pressure/brachial systolic pressure ratio dropping from 0.67 +/- 0.012 to 0.29 +/- 0.017 (p less than 0.001) on the patient side and from 0.58 +/- 0.013 to 0.48 +/- 0.018 (p less than 0.001). Twenty-six of 53 patients (49%) developed ischemic symptoms in response to compression of the remaining patent ICA system. In contrast, only 8 of 122 patients (6.5%) without ICA occlusion developed any symptoms of cerebral dysfunction (p less than 0.001). This study suggests embolic events rather than flow reduction may be of greater importance in the production of new symptoms and that contralateral flow is critical to normal cerebral function in half the population with ICA occlusion.

Fulminant Drechslera sinusitis in an immunocompetent host

Mycotic infections of the paranasal sinuses are rare. Sinusitis caused by Drechslera spicifera, a common saprophytic dematiacious fungus, has previously been reported in only three immunocompetent patients. Aggressive growth characteristics were not described in any of these reports. The case of a young immunocompetent pregnant woman with fulminant sinusitis caused by Drechslera spicifera is presented. The tumor, which invaded both orbits and the anterior cranial fossa, was rapidly progressive during pregnancy. After delivery of the baby, a combined craniofacial approach was used to excise the sinus mass while adjacent normal tissues were preserved. The pathophysiology and mycology of this uncommon sinus pathogen are reviewed. This case emphasizes the need for prompt surgical intervention to avoid potentially life-threatening complications from a fulminant mycotic process in the paranasal sinuses. Indications for postoperative chemotherapy with amphotericin B are discussed.

Carotid artery atheroma: comparison of preoperative B-mode ultrasound appearance with carotid endarterectomy specimen pathology

This paper describes a prospective study comparing the preoperative Duplex ultrasound appearance of carotid bifurcation atheroma with the pathological characteristics found in the endarterectomy specimens of the same vessels. Initial studies of carotid atheroma using Duplex scanning classified plaques into heterogeneous and homogeneous and found a strong correlation between heterogeneous lesions and the presence of intraplaque haemorrhage or ulceration in the endarterectomy specimen. The B-mode classification of plaque appearance described in this paper is an expansion of the above classification. The study group comprised 220 patients who underwent 244 procedures. The indication for carotid endarterectomy was symptomatic disease in the great majority of cases. We found a high incidence of unstable plaque pathology in the operative specimens, and a predominance of the more echolucent ultrasound plaque appearances (types 1 and 2). There is a statistically significant relationship (p less than 0.001) between ultrasound appearance types 1 and 2 and the presence of either intraplaque haemorrhage or ulceration in the endarterectomy specimen.

Carotid artery disease: the influence of diabetes mellitus

Patients with diabetes mellitus are more prone to stroke than non-diabetic patients. Using Duplex ultrasound imaging of the carotid bifurcation, we have found it possible to classify atherosclerotic plaques into four groups which appear to reflect the plaque pathology. Using this classification we have found that diabetics and non-diabetics have similar ultrasound plaque type distributions in symptomatic patients. Further subdivision of the diabetic patients on the basis of their mode of diabetic control has shown that insulin treated diabetics tend to show little evidence of intraplaque haemorrhage and ulceration. These features suggest that factors other than atherosclerosis at the carotid bifurcation may be responsible for the increased stroke risk in diabetic patients. Diabetic microangiopathy and reduced vessel compliance due to medial calcification have been suggested as possible factors. Insulin treatment of diabetics may protect against the development of occlusive atherosclerosis.

Pyoderma gangrenosum involving the head and neck

Pyoderma gangrenosum (PG) is a rare pathergy associated with systemic diseases such as ulcerative colitis and polycythemia vera. Its recognition in the differential diagnosis of other ulcerative lesions is important in managing an affected patient. A patient who developed lower extremity, oral, and cervical manifestations of this disease on separate occasions is presented. It is imperative that every clinician be aware of this entity because of the potential untoward effects of delayed or improper treatment including unnecessary surgery. Systemic and intralesional steroids are the treatment of choice.

Transluminal balloon angioplasty in diabetic peripheral vascular disease

Transluminal (balloon) angioplasty of iliac or superficial femoral stenoses in 18 diabetic patients resulted in a significant improvement in ankle/brachial systolic pressure index with marked symptomatic improvement in 16, little change in one and deterioration requiring arterial bypass surgery in one patient. Follow-up for 12 months or more showed that the initial good results were sustained despite a downward drift in ankle pressures. These findings indicate that transluminal angioplasty has a useful place in the management of proximal atherosclerotic stenotic lesions in diabetic patients with symptomatic peripheral vascular disease.