Tomorrow's world: atherosclerosis in the year 2000

Atherosclerosis is an increasing problem, largely due to lifestyle changes. Lipid accumulates in artery walls throughout life, and infiltration into the subintimal space of cholesterol and cholesterol esters and of inflammatory cells can lead to narrowing, clotting, thrombosis and death. Lipid-lowering agents, particularly statins [(3-hydroxy-3-methylglutarate coenzyme A (HMG-CoA) reductase inhibitors] represent one important approach to treatment. They work by blocking the conversion of 3-hydroxy-3-methylglutarate into mevalonate, a precursor of cholesterol. The West Of Scotland Coronary Prevention Study (WOSCOPS) was a large prospective randomised study comparing the effects of pravastatin versus that of placebo in 6595 middle-aged men. In the pravastatin group the rate of fatal or non-fatal myocardial infarction was reduced by one-third over 5 years, the rate of cardiovascular deaths by one-third, and overall deaths by 22% relative to the placebo group. Implications of the results are considered and the results of the US-CARE study are compared. Discussion of relative and absolute risk, and continuous and discrete risk factors leads to the formulation of rational cost/beneficial strategies for decreasing cardiovascular risk by targeting high-risk individuals with lipid-lowering drugs.

Defective regulation of triglyceride metabolism by insulin in the liver in NIDDM

Insulin administration to healthy subjects inhibits the production of very low density lipoprotein (VLDL)1 (Svedbergs flotation (Sf) rate 60-400) without affecting that of VLDL2 (Sf 20-60) sub-class. This study was designed to test whether this hormonal action is impaired in non-insulin-dependent diabetes mellitus (NIDDM). We studied six men with NIDDM (age 53 +/- 3 years, body mass index 27.0 +/- 1.0 kg/m2, plasma triglycerides 1.89 +/- 0.22 mmol/l) during an 8.5 h infusion of saline (control) and then in hyperinsulinaemic (serum insulin approximately 540 pmol/l) conditions during 8.5 h infusions of glucose and insulin to give either hyper- and normoglycaemic conditions. [3-2H]-leucine was used as tracer and kinetic constants derived using a non-steady-state multicompartmental model. Compared to the control study, patients with NIDDM reduced VLDL1 apo B production by only 3 +/- 8% after 8.5 h of hyperinsulinaemia (701 +/- 102 vs 672 +/- 94 mg/day respectively, NS) in hyperglycaemic conditions and by 9 +/- 21% under normoglycaemic conditions (603 +/- 145 mg/day). In contrast, in normal subjects insulin induced a 50 +/- 15% decrement in VLDL1 apo B production (p < 0.05). Direct synthesis of VLDL2 apo B in patients with NIDDM was not markedly affected by insulin. We conclude that a contributory factor to hypertriglyceridaemia in NIDDM is the inability of insulin to inhibit acutely the release of VLDL1 from the liver, despite efficient suppression of serum nonesterfied fatty acids.

Lipoprotein subfraction concentrations in preeclampsia: pathogenic parallels to atherosclerosis

OBJECTIVE

To determine whether large triglyceride-rich lipoproteins, very-low-density lipoprotein1 (VLDL1), and small, dense low-density lipoprotein (LDL-III), are significantly increased in women with preeclampsia compared with concentrations seen in normal pregnancy.

METHODS

Plasma concentrations of very-low-density and low-density lipoprotein subfractions and pre-heparin hepatic lipase activity were measured in eight women with preeclampsia and in eight healthy pregnant controls matched for age, gestational age, and weight.

RESULTS

Women with preeclampsia exhibited higher median plasma triglyceride concentrations (3.68 versus 1.93 mmol/L, P = .004) compared with controls. This was reflected in an almost threefold increase in median VLDL1 (184 versus 68 mg/dL, P = .002) and a twofold increase in very-low-density lipoprotein2 (VLDL2) (146 versus 76 mg/dL, P = .014), whereas total plasma cholesterol, intermediate-density lipoprotein, and total LDL concentration were the same in subjects and controls. Furthermore, women with preeclampsia demonstrated significantly lower concentrations of the large, buoyant LDL subfractions, LDL-I and LDL-II, and markedly elevated median plasma concentrations of small, dense LDL, LDL-III (170 versus 55 mg/dL, P = .024). High-density lipoprotein-cholesterol concentration also was significantly lower (P = .021), and pre-heparin hepatic lipase activity was significantly elevated (29 versus 18 mumol fatty acids/mL/hour, P = .041) in the preeclamptic group. The concentration of small, dense LDL correlated positively with plasma triglyceride concentration (r2 = 0.504, P = .002).

CONCLUSION

Women with preeclampsia exhibit markedly elevated concentrations of triglyceride-rich lipoproteins in the circulation. These particles are potential contributors to endothelial dysfunction and the expression of preeclampsia, both directly and, indirectly, through the generation of small, dense LDL.

In vivo metabolism of apo A-I and apo A-II in subjects with apo A-I(Lys107-->0) associated with reduced HDL cholesterol and Lp(AI w AII) deficiency

Apolipoprotein A-I (apo A-I) and apolipoprotein A-II (apo A-II) represent 80 90% of the protein content of high density lipoproteins (HDL). Previously we have identified a Finnish family with an apo A-I variant (Lys107-->0) associated with reduced plasma HDL cholesterol level and decreased lipoprotein (Lp)(AI w AII) concentration compared to unaffected family members. To determine the in vivo metabolism of apo A-I and apo A-II in the carriers of apo A-I (Lys107-->0) variant we radioiodinated normal apo A-I with 125I and apo A-II with 131I and compared the kinetic data of two heterozygous apo A-I(Lysl07-->0) patients (HDL cholesterol leves 0.31 and 0.69 mmol/l) to that of eight normolipidemic, healthy control subjects. Plasma radioactivity curves of 125I-labelled normal apo A-I of the patients demonstrated accelerated clearance of apo A-I compared to control subjects. In the two patients the fractional catabolic rates (FCR) of apo A-I were 0.347/day and 0.213/day, respectively, while the mean FCR of apo A-I of the control subjects was 0.151 +/- 0.041/day. Similarly, the plasma decay curves of the 131I-labelled apo A-II showed more rapid clearance of apo A-II in the two patients than in control subjects. The FCR of apo A-II in the two patients were 0.470/day and 0.234/day, while the mean FCR of apo A-II in control subjects was 0.154 +/- 0.029/day. The calculated production rates of apo A-I were similar in patients and in control subjects, and the production rates of apo A-II were significantly higher in patients than in control subjects. Our results show that the Lp(AI w AII) deficiency in patients with the apo A-I(Lys107-->0) is associated with increased fractional catabolic rates of normal apo A-I and apo A-II, while the production rates of these apolipoproteins are normal (apo A-I) or slightly increased (apo A-II).

Clinicopathologic studies of thymic carcinoids in multiple endocrine neoplasia type 1

Thymic carcinoid is part of the multiple endocrine neoplasia type 1 (MEN1) syndrome occurring predominantly in male patients who were heavy smokers, presenting most commonly in middle age. In contrast with metastatic midgut carcinoids, MEN1-related thymic carcinoid is not associated with carcinoid syndrome, nor is it associated with Cushing syndrome, in contrast with sporadic thymic carcinoids. Local invasion and metastasis are common. Prognosis is poor because of late detection, lack of effective treatment, and the aggressive nature of the tumor. All patients with thymic carcinoids should be investigated for MEN1, including thorough clinical evaluation and family studies. Anterior mediastinal lesions in MEN1 male patients should be considered thymic carcinoids until proven otherwise. All male MEN1 patients and asymptomatic gene carriers should be warned of the risk of thymic carcinoids and the possible link to smoking. Computed tomography (CT) of the chest is recommended on first screening for MEN1 in male patients more than 25 years of age, followed by yearly chest X-rays and chest CT every 3 years. Prophylactic thymectomy should be carried out during subtotal or total parathyroidectomy on MEN1 patients.

Projecting rates of urbanisation in England, 1991-2016: method, policy application and results

"The rate of conversion of land from rural to urban uses has been a central concern of the British planning system. Despite this interest, however, the factual basis of the debate on the pace of urban growth, its form and distribution has been extremely weak. The reason for this is lack of appropriate data. This paper reports research on two new data sources on land use--a digital database of the boundaries of tracts of urban land in 1981 and 1991 and the Land Use Change Statistics--to analyse recent urban growth in England and, in conjunction with current household projections, to estimate the likely extent of urbanisation in 2016. In addition to assessing the geographical distribution of this growth, the paper draws out some implications for policy analysis of the method of projecting the extent of land in urban use."

Definition of the minimal MEN1 candidate area based on a 5-Mb integrated map of proximal 11q13. The European Consortium on Men1, (GENEM 1; Groupe d'Etude des Néoplasies Endocriniennes Multiples de type 1)

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder with a high penetrance characterized by tumors of the parathyroid glands, the endocrine pancreas, and the anterior pituitary. The MEN1 gene, a putative tumor suppressor gene, has been mapped to a 3- to 8-cM region in chromosome 11q13 but it remains elusive as yet. We have combined the efforts and resources from four laboratories to form the European Consortium on MEN1 with the aims of establishing the genetic and the physical maps of 11q13 and of further narrowing the MEN1 region. A 5-Mb integrated map of the region was established by fluorescence in situ hybridization on both metaphase chromosomes and DNA fibers, by hybridization to DNA from somatic cell hybrids containing various parts of human chromosome 11, by long-range restriction mapping, and by characterization of YACs and cosmids. Polymorphic markers were positioned and ordered by physical mapping and genetic linkage in 86 MEN1 families with 452 affected individuals. Two critical recombinants identified in two affected cases placed the MEN1 gene in an approximately 2-Mb region around PYGM, flanked by D11S1883 and D11S449.

Natural history and prognosis of untreated stage I epithelial ovarian carcinoma

PURPOSE

The aim of this study was to investigate the independent significance of prognostic factors in stage I invasive epithelial ovarian cancer (EOC).

PATIENTS AND METHODS

Between 1980 and 1994, all patients with stage I EOC (borderline tumors excluded) following surgical resection were entered onto this study. No patient received adjuvant therapy and patients were monitored as follows: years 1 to 2-physical examination and serum CA125 every 3 months and computed tomographic (CT) scan every 6 months; years 3 to 5-physical examination and serum CA125 every 6 months and CT scan yearly; years 5 to 10-annual physical examination and serum CA125, with CT scan if clinically indicated.

RESULTS

A total of 194 patients entered the study. The median patient age was 54 years (range, 15 to 83), and the median follow-up duration 54 months (range, 7 to 157). Five-year survival rates were as follows: stage IA, 93.7%; stage IB, 92%; and stage IC, 84%. Multivariate analysis using Cox's regression identified grade (P < .001), presence of ascites (P = .05), and surface tumor (P < .01) as independent poor prognostic factors. International Federation of Gynecology and Obstetrics (FIGO) substage did not appear to have independent prognostic significance. Intraoperative capsule rupture was not found to be prognostically significant. The impact of pre-operative rupture remains unclear.

CONCLUSION

This is an important series, as no patient received adjuvant therapy, and represents the natural history of surgically resected stage I EOC.

Sporadic primary hyperparathyroidism in the setting of multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN 1) is an autosomal dominant disease characterized by neoplasia involving the parathyroid glands, the endocrine pancreas, the duodenum, and the anterior pituitary. The most commonly involved gland is the parathyroid gland, which has been found to be abnormal in 90% to 95% of all patients with MEN 1. The disease process is invariably multiglandular and histologically described as either hyperplasia or multiple adenoma, although the histological distinction between the 2 entities remains difficult and controversial. The prevalence of MEN 1 is approximately 0.002 in 100, whereas the prevalence of sporadic primary hyperparathyroidism due to a solitary adenoma is estimated to be as high as 1 in 100.(2.3) We report herein the first case of sporadic primary hyperparathyroidism in the setting of MEN 1 based on clinical, biochemical, pathological, and genetic studies.

Influence of plasma lipid and LDL-subfraction profile on the interaction between low density lipoprotein with human arterial wall proteoglycans

Low density lipoprotein (LDL) is known to bind to arterial wall proteoglycans (APG), an interaction which may initiate cholesterol deposition in the arterial wall. The objective of this study was to determine whether a predominance of small, dense LDL (LDL-III, d = 1.044-1.063 g/ml) in the circulation in association with an atherogenic lipoprotein phenotype (ALP) (i.e. LDL-III > 100 mg/dl, an elevated plasma triglyceride and a low high density lipoprotein cholesterol) alters LDL reactivity towards APG. Total LDL (d = 1.019-1.063 g/ml) was isolated from 59 patients undergoing coronary angiography (39 males and 20 females) and the LDL subfraction profile determined by non-equilibrium density gradient centrifugation. A binding assay was developed in which total LDL (0.1 mg/ml apo LDL) was mixed with a standard preparation of APG containing 2.5 micrograms/ml chondroitin sulphate and the extent of APG-LDL complex formation followed by absorbance measurement and the amount of precipitated LDL cholesterol. APG-LDL complex formation was positively associated with (a) the percentage of LDL-III within total LDL (r = 0.48, P < 0.0001); (b) the plasma triglyceride level (r = 0.27, P < 0.04); and negatively associated with (a) the percentage of the buoyant LDL-I (d = 1.019-1.033 g/ml)(r = -0.47, P < 0.0001); and (b) the HDL cholesterol concentration (r = -0.37, P < 0.004). There was no association with the percentage of the major LDL species LDL-II. When the patients were divided according to the presence or absence of an ALP i.e. LDL-III greater or less than 100 mg/dl respectively, proteoglycan-LDL complex formation was significantly higher in the former compared to the latter group of patients (P < 0.0001). This study therefore provides evidence that the extent of the interaction of LDL with APG varies considerably between individuals and is enhanced in the presence of ALP. It is postulated that the increased atherogenicity associated with ALP may in part be due to prolonged and enhanced retention of LDL by the arterial wall.

Effects of the selective angiotensin II receptor antagonists losartan and PD123177 in animal models of anxiety and memory

There is increasing interest in the potential functional role of the octapeptide angiotensin II (AII) in psychiatric and cognitive disorders. The novel angiotensin II (AII) receptor antagonists, losartan and PD123177, selective for the AT1 and AT2 receptor subtypes respectively, constitute important pharmacological tools for the assessment of the behavioural consequences of modulation of AII function. The present series of studies investigated the effects of each compound in two animal models of anxiety, the rat elevated zero-maze and mouse light/dark box, and two models of working memory in the rat, the operant delayed matching to position (DMTP) task and the spatial reinforced alternation test in the T-maze. Our data indicate that both compounds (0.01-10 mg/kg s.c.) were without significant effect in any of the behavioural assays. Using the present methods and strains of laboratory rodents, these findings provide no support for the involvement of AII receptor function in the mediation of anxiety of working memory.

Sensitive methods to study human apolipoprotein B metabolism using stable isotope-labeled amino acids

The objective of the study was to develop a sensitive method using stable isotope-labeled tracers that would permit the determination of apolipoprotein B (apoB) metabolism in very low-density lipoprotein subfractions (VLDL1, Sf 60-400; VLDL2, Sf 20-60), intermediate-density lipoprotein (IDL, Sf 12-20), and low-density lipoprotein (LDL, Sf 0-12). Six normolipidemic subjects were given trideuterated leucine, and its clearance from plasma and appearance in the four apoB-containing lipoprotein fractions were followed by use of a highly sensitive gas chromatography-mass spectrometry technique in which the m + 3-to-m + 2 ion ratio was selectively monitored. This analytic approach permitted the precise measurement of low enrichments in IDL and LDL and extension of the turnover out to 250-300 h. A compartmental model was developed to derive rate constants from the plasma and apoB enrichment curves. The model was uniquely identifiable once parameter dependencies had been introduced to reduce the number of unknowns. Values were obtained for apoB input into all lipoprotein density intervals, together with rates of interconversion and catabolism; these agreed well with results from radioiodinated tracer experiments. An alternative model structure was also explored in which input occurred only into VLDL1. Altering the protocol of tracer administration (bolus vs. primed constant infusion) and dose (over a 10-fold range) had no influence on the results obtained. The analytic and modeling approach described will permit stable isotopes to be used to elucidate key features of apoB metabolism in normal and pathological states.

Genetic immunization of rainbow trout (Oncorhynchus mykiss) against infectious hematopoietic necrosis virus

Plasmid vectors encoding the infectious hematopoietic necrosis virus (IHNV) nucleoprotein or glycoprotein gene under the control of a cytomegalovirus promoter were used to immunize rainbow trout (Oncorhynchus mykiss) against IHNV. The plasmid DNA was injected into the skeletal muscle of rainbow trout fry, and immunization was determined by the detection of virus-neutralizing and enzyme-linked immunosorbent assay antibody activity, and by protection against live virus challenge. Fish injected with the glycoprotein-encoding plasmid pCMV4-G, either alone or in combination with the nucleoprotein-encoding plasmid pCMV4-N, generated glycoprotein-specific and virus-neutralizing antibody responses. The vaccinated fish were also protected from subsequent IHNV challenge. Fish receiving pCMV4-N alone did not produce measurable virus-specific antibody and were killed by IHNV infection. These studies show that DNA vaccination will protect rainbow trout against the lethal effects of IHNV infection.

Effects of colestipol alone and in combination with simvastatin on apolipoprotein B metabolism

The effects of colestipol therapy alone (20 g/d) or combined with simvastatin (20 mg/d) were examined in a group of eight male patients with primary moderate hypercholesterolemia (total cholesterol > or = 6.5 mmol/L [> or = 250 mg/dL]) who had undergone coronary artery bypass grafting more than 3 months previously. Colestipol therapy decreased total cholesterol by 14% (P < .001) and LDL cholesterol (LDL-C) by 23% (P < .001), while dual therapy decreased total cholesterol by 38% and LDL-C by 52% (both P < .001 versus baseline). No significant changes were observed in plasma triglyceride, VLDL cholesterol, or HDL cholesterol levels. VLDL subfraction turnovers were conducted at baseline and again on each regimen. ApoB kinetic parameters derived from a multicompartmental model suggested that colestipol therapy resulted in an expansion of the total VLDL apoB pool (36%, P < .05) that was largely due to a fall in the clearance rate of VLDL1 apoB (49%), while the LDL apoB pool decreased 23% as a result of diminished direct LDL input. The model used also revealed that addition of simvastatin to the resin therapy caused increases in the fractional transfer rates of VLDL2 to IDL and IDL to LDL together with a 37% increment in the LDL apoB fractional catabolic rate. Compared with baseline, combined therapy generated falls in both IDL (35%, P = .01) and LDL (37%, P < .04) apoB pools due to enhanced clearance of IDL (214%, P < .03) and reduced total input of LDL (39%, P < .003).

Accumulation of large very low density lipoprotein in plasma during intravenous infusion of a chylomicron-like triglyceride emulsion reflects competition for a common lipolytic pathway

Very low density lipoproteins (VLDL) are produced in the liver and contain apolipoprotein (apo) B-100 and endogenous lipids. By contrast, ingestion of fat leads to formation of chylomicrons containing apoB-48 secreted from the intestine. In this study, a 60-min intravenous infusion of a chylomicron-like triglyceride emulsion was given to healthy young men to examine whether competition between chylomicrons and VLDL for the same lipolytic pathway explains the increase in VLDL seen after meals. The responses of two major VLDL subfractions were determined by measuring the concentrations of apoB-100 in fractions of triglyceride-rich lipoproteins with Svedberg flotation rates of 60-400 (large VLDL) and 20-60 (small VLDL) that were separated from plasma by density gradient ultracentrifugation. A threefold elevation in plasma triglycerides was observed during the infusion together with a consistent linear increase of large VLDL. The rate at which large VLDL accumulated in plasma differed markedly among individuals and was not enhanced by doubling of the infusion rate. The response of small VLDL was more heterogeneous; however, a decrease was seen in most subjects. The combined pattern for the two VLDL species is what would be expected if large VLDL particles are the precursors of smaller VLDL species and if lipolysis of large VLDL is inhibited through competition from the triglyceride emulsion. The extent to which the triglyceride emulsion inhibited the lipolysis of VLDL and/or influenced the synthesis rate of large VLDL was estimated from simultaneous stable isotope studies. The emulsion caused a 75-90% block of the conversion of large VLDL apoB to small VLDL apoB and there was no sign of enhanced synthesis of large VLDL after infusion of the triglyceride emulsion. The corollary of these findings is that chylomicrons and their remnants impede the normal lipolytic degradation of VLDL and could thereby be indirectly implicated in the generation of atherogenic remnant lipoproteins.

Transformation of residual mature ovarian teratoma to adenocarcinoma 10 years after initial treatment

A patient with a residual mature solid ovarian teratoma, which underwent malignant transformation to an adenocarcinoma 10 years after previous successful treatment, is presented. This case history illustrates that patients with residual mature disease require long term follow-up.

Prevention of coronary heart disease in clinical practice: a commentary on current treatment patterns in six European countries in relation to published recommendations

Market research surveys can be a source of up-to-date information about current clinical practices. Data from one such survey, Cholesterol Monitor (made available by Merck & Co., Inc., Whitehouse Station, N.J., USA) was examined to ascertain to what extent management of cholesterol in six European countries conforms with the advice of the joint Task Force of the European Society of Cardiology, European Atherosclerosis Society and European Society of Hypertension for prevention of coronary heart disease (CHD). Rates of cholesterol testing in patients with CHD varied from less than 50% in the UK to more than 80% in France and Italy. Across Europe, the average cholesterol levels in surveyed patients was 6 mmol/l, and the average intervention level was 7.5 mmol/l. In all countries, there was evidence of a substantial treatment gap, even among high-risk patients with established CHD. This gap took the form of non-treatment of a proportion of patients whose risk status merited intervention on the basis of expert recommendations and the results of the Scandinavian Simvastatin Survival Study (in which sustained lowering of total and low-density lipoprotein cholesterol reduced total and coronary mortality in patients with baseline total cholesterol as low as 5.5 mmol/l). The findings indicate that a concerted programme of physician education is required if the recommendations of the joint Task Force are to be put into effect, and if the present nontreatment/undertreatment of cholesterol in high-risk patients is to be corrected.

Should doctors be more proactive as advocates for victims of violence?

Currently the management of adult victims of violence by general practitioners and accident and emergency departments is reactive, concerned almost exclusively with the management of physical injuries. Professor Jonathan Shepherd outlines some ideas for a more proactive approach on the part of doctors to improve the protection and support of vulnerable people; to deal with psychological sequelae; to take the responsibility of making an official complaint to the police away from seriously injured people, who are unable to give or withhold consent to disclosure; and to prevent assailants inflicting further injuries. We asked a sociologist, a psychiatrist, a moral philosopher, and a police surgeon for their comments.