Progression and regression of the atherosclerotic plaque

In animals in which atherosclerosis was induced experimentally (by a high cholesterol diet) regression of the atherosclerotic lesion was demonstrated after serum cholesterol was reduced by cholesterol- lowering drugs or a low-fat diet. Whether regression of advanced coronary arterly lesions also takes place in humans after a similar intervention remains conjectural. However, several randomized studies, primarily employing lipid-lowering intervention or comprehensive changes in lifestyle, have demonstrated, using serial angiograms, that it is possible to achieve less progression, arrest or even (small) regression of atherosclerotic lesions. The lipid-lowering trials (NHBLI, CLAS, POSCH, FATS, SCOR and STARS) studied 1240 symptomatic patients, mostly men, with moderately elevated cholesterol levels and moderately severe angiographic-proven coronary artery disease. A variety of lipid-lowering drugs, in addition to a diet, were used over an intervention period ranging from 2 to 3 years. In all but one study (NHBLI), the progression of coronary atherosclerosis was less in the treated group, but regression was induced in only a few patients. The overall relative risk of progression of coronary atherosclerosis was 0 x 62 and 2 x 13, respectively. The induced angiographic differences were small and did not produce any significant haemodynamic benefit. The most important result was tht the disease process could be stabilized in the majority of patients. Three comprehensive lifestyle change trials (the Lifestyle Heart study, STARS and the Heidelberg Study) studied 183 patients, who were subjected to stress management, and/or intensive exercise, in addition to a low fat diet, over a period ranging from 1 to 3 years. All three trials demonstrated less progression, and more regression with overall relative risks of 0 x 40 and 2 x 35 respectively, in the intervention groups. Angiographic trials demonstrated that retardation or arrest of coronary atherosclerosis was possible after an intervention, but the ultimate goal, regression of the lesion, was only achieved in a small number of patients. However, the ability to stabilize coronary atherosclerosis is a considerable achievement for those patients with coronary atherosclerosis.

Gene diversity at allozyme loci in the cottonwood leaf beetle, Chrysomela scripta

Gene diversity was studied in beetles collected from a poplar plantation at Ames, Iowa. The beetles are widely distributed throughout North America wherever poplars (Populus spp) occur. Of 38 loci interpretable by simple Mendelian criteria, 22 were polymorphic (58%). Nei's mean heterozygosity per locus was 20.1 +/- 4.0%. A mean 2.29 +/- 1.35 alleles per locus was detected. The foregoing levels of diversity are typical of Coleoptera. There were significant deviations from Hardy-Weinberg expectations at six loci, and of these loci, four deviations were judged to have been caused by technical problems in resolving heterozygotes. Twelve polymorphic loci are considered suitable to carry out studies on the breeding structure of this important pest.

The results of denatured homologous vein grafts as conduits for secondary haemodialysis access surgery

OBJECTIVES

To determine the value of denatured homologous vein grafts as a conduit for secondary haemodialysis access.

DESIGN

Retrospective clinical study.

SETTING

2 University Hospitals.

MATERIALS AND METHODS

One-hundred-and-twenty-five patients received 195 grafts over a period of five years. Fifty-six first grafts (45%) functioned without complications throughout the study period of 5.8 years.

MAIN RESULTS

Primary patency was 57% after 1 year and 25% after 3 years of follow-up. Of the initial grafts, 69 (55%) needed 161 interventions, for thrombosis (n = 59), stenosis (n = 43), failure beyond repair (n = 40), aneurysm (n = 12), infection (n = 4), steal syndrome (n = 1), and other causes (n = 2). Secondary patency was 76% at 1 year and 52% at 3 years of follow-up. A major advantage of these grafts was the low rate (2.6%) of infection. Aneurysm formation occurred 17 times in 195 grafts (8.7%).

CONCLUSIONS

Denatured homologous vein graft is a good alternative in secondary access surgery.

Von Hippel-Lindau disease: new strategies in early detection and treatment

Von Hippel-Lindau disease is an autosomal dominant inherited disorder causing hemangioblastomas of the central nervous system (CNS), retinal hemangiomas, renal cell carcinomas, pheochromocytomas, pancreatic and liver cysts, and epididymal cystadenomas.

PURPOSE

Since 1976, we have periodically screened for the lesions in a large affected family and were able to evaluate new strategies in detection and treatment.

PATIENTS AND METHODS

A total of 23 individuals underwent the screening program. A multidisciplinary team of physicians was involved.

RESULTS

In 13 patients (7 females and 6 males), a total of 31 tumors was detected; hemangioblastoma of the CNS (9), retinal angioma (4), renal involvement (8), pheochromocytoma (4), pancreatic lesions (4), and liver lesions (2) were diagnosed by periodic family screening. On the basis of more than 10 years of experience and current literature, new criteria for diagnosis and treatment have been proposed.

CONCLUSION

The von Hippel-Lindau disease gene appears to be a tumor suppressor gene, and its absence or a defect in its structure is responsible for the predisposition to the disease. Tumor development depends on a somatic second mutation in the homologous allele. That means, in disease-gene carriers, tumor growth may begin at any age. Most of the lesions can be treated successfully when diagnosed in time. Periodic screening by a multidisciplinary team has to be continued lifelong.

Changes in blood transfusion practices after the introduction of consensus guidelines in Mwanza region, Tanzania

OBJECTIVE

To assess the effect of introducing consensus guidelines on avoidable blood transfusions in Mwanza region, Tanzania.

METHODS

Avoidable blood transfusions were determined among 842 blood transfusion recipients in eight hospitals in 1991. In a workshop with senior health workers from the region, consensus guidelines for the prescription of blood transfusions were developed and introduced in the hospitals and after 7 months intervention data were collected on 1042 blood transfusion recipients. The 1991 and 1992 data were compared to estimate the change in the proportion of avoidable blood transfusions.

RESULTS

In blood transfusion recipients aged < 5 years there was a significant reduction in the proportion of avoidable blood transfusions from 257 (52%) out of 498 to 197 (33%) out of 595 (P < 0.001), especially at the peripheral hospitals. For children the proportion decreased from 25 to 17% (P < 0.05) and for operated patients the percentage remained at 24%. In pregnant women there was a significant increase in the proportion of avoidable blood transfusions from 10 to 27% and in adults from 37 (25%) out of 146 to 121 (50%) out of 242. The improvement in peripheral hospitals was offset by a similar deterioration in the referral hospital, thus no overall reduction was achieved in the proportion of avoidable blood transfusions.

CONCLUSION

The development and introduction of consensus guidelines was not sufficient to change prescribing practice. The proportion of avoidable blood transfusions decreased only in hospitals where compliance was maintained through regular clinic meetings and strict supervision by senior medical staff.

Prevalence of antibodies to hepatitis C virus in a Dutch group of haemodialysis patients related to risk factors

In January 1992, 122 chronic haemodialysis patients (> 9 months dialysis) from the University Hospital Utrecht and its outpatient dialysis facility were tested for the presence of anti-hepatitis C virus (HCV) antibodies. The objective was to identify risk factors for HCV infection in chronic haemodialysis patients in an attempt to explain the high prevalence of anti-HCV antibodies found among such haemodialysis patients. A second generation enzyme linked immuno-sorbent assay (EIA) was used as a screening test. Results were confirmed by a recombinant immunoblot assay and by the polymerase chain reaction (PCR). Four (3.3%) of 122 patients reacted positively in the EIA screening test as well as in the immunoblot assay; three of these were positive using PCR. None of the patients with anti-HCV antibodies had received blood products other than blood from transfusions, none had markers for a hepatitis B virus (HBV) infection or admitted intravenous drug abuse. A total number of 2395 units of blood, unscreened for HCV, had been administered to our dialysis group, an average of 19.6 (SD 44.7) units per patient. The seroprevalence of anti-HCV antibodies among blood donors in Utrecht was 0.03%. Patients with antibodies to HCV had been on dialysis longer than those dialysis patients without HCV antibodies (odds ratio 1.8, 95% CI 0.99-3.29). We conclude that the risk for HCV infection for this dialysis group can only partially be attributed to unscreened blood transfusions. Haemodialysis itself may play a role in transmission of HCV.

Prognosis in hypertrophic cardiomyopathy observed in a large clinic population

Overall annual cardiac mortality in hypertrophic cardiomyopathy (HC) has been reported to be between 2 and 4%, although these numbers are primarily from retrospective studies of patients referred to large research institutions. A clinic population of 113 patients with HC was prospectively studied to assess cardiac mortality in the overall group and in selected subgroups commonly thought to be at high risk for sudden death. The mean age at diagnosis was 37 +/- 16 years. During follow-up, there were 11 cardiac and 2 noncardiac deaths. The annual cardiac mortality was 1% (95% confidence interval 0.2-1.8%). Because of the small number of deaths, relative risk for cardiac death was not significantly different in the presence of young age (< or = 30 years), family history of HC and sudden death, history of syncope or previous cardiac arrest, or both, ventricular tachycardia on 24-hour Holter monitoring, or septal myotomy/myectomy for refractory symptoms and outflow tract obstruction. It is concluded that HC has a relatively benign prognosis (1% annual cardiac mortality) that is 2 to 4 times less than that previously reported.

Luminal narrowing after percutaneous transluminal coronary angioplasty. A study of clinical, procedural, and lesional factors related to long-term angiographic outcome. Coronary Artery Restenosis Prevention on Repeated Thromboxane Antagonism (CARPORT) Study Group

BACKGROUND

The renarrowing process after successful percutaneous transluminal coronary angioplasty (PTCA) is now believed to be caused by a response-to-injury vessel wall reaction. The magnitude of this process can be assessed by the change in minimal lumen diameter (MLD) at follow-up angiography. The aim of the present study was to find independent patient-related, lesion-related, and procedure-related risk factors for this luminal narrowing process. A model that accurately predicts the amount of luminal narrowing could be an aid in patient or lesion selection for the procedure, and it could improve assessment of medium-term (6 months) prognosis. Modification or control of the identified risk factors could reduce overall restenosis rates, and it could assist in the selection of patients at risk for a large loss in lumen diameter. This population could then constitute the target population for pharmacological intervention studies.

METHODS AND RESULTS

Quantitative angiography was performed on 666 successfully dilated lesions at angioplasty and at 6-month follow-up. Multivariate linear regression analysis was performed to obtain variables with an independent contribution to the prediction of the absolute change in minimal lumen diameter. Diabetes mellitus, duration of angina < 2.3 months, gain in MLD at angioplasty, pre-PTCA MLD, lesion length > or = 6.8 mm, and thrombus after PTCA were independently predictive of change in MLD. Overall prediction of the model was poor, however, percentage-correct classification for a predicted change between -0.1 to -0.4 mm was approximately 10%. Lesions showing no change or regression (change > -0.1 mm) and lesions showing large progression (< or = -0.4 mm) were more predictable (correct classification, 59.5% and 49.7%, respectively).

CONCLUSIONS

Renarrowing after successful PTCA as determined with contrast angiography is a process that cannot be accurately predicted by simple clinical, morphological, and lesion characteristics.

Pharmacological approaches to the prevention of restenosis following angioplasty. The search for the Holy Grail? (Part II)

Part I of this article reviewed the results of studies investigating the effectiveness of antithrombotic, antiplatelet, antiproliferative, anti-inflammatory, calcium channel blocker and lipid-lowering drugs in preventing or reducing restenosis after angioplasty. However, despite 15 years of clinical experience and research in the field of restenosis prevention, this has not yet resulted in the revelation of unequivocal beneficial effects of any particular drug. Other newer approaches likely to receive more attention in the future include antibodies to growth factors, gene transfer therapy and antisense oligonucleotides. Whether there is a feasible monotherapy, whether we have to focus on a drug combination, or whether we are only searching for 'the Holy Grail' remain to be answered.

Pharmacological approaches to the prevention of restenosis following angioplasty. The search for the Holy Grail? (Part I)

Luminal renarrowing after balloon angioplasty still hampers the long term vessel patency in a substantial percentage of patients. Morphologically, the restenotic lesion comprises hyperplasia of intimal tissue, which is mainly characterised by proliferation of smooth muscle cells of the synthetic type with abundant extracellular matrix production, chiefly composed of proteoglycans. Unravelling the underlying pathophysiological process enables more specific intervention in basic interactions and cell responses. Critical events in the development of restenotic tissue are platelet aggregation and thrombus formation, while the release of several mediators promotes proliferation and migration of various cell types. All of these steps give access for a diversity of pharmacological interventions. With this in mind, antithrombotic, antiplatelet, antiproliferative, antiinflammatory, calcium channel blocking and lipid-lowering drugs have been investigated in the prevention of restenosis. Part II of this article reviews newer approaches, such as antibodies to growth factors, gene transfer and antisense oligonucleotides.

Blood transfusion practices in Mwanza Region, Tanzania. Bugando Medical Centre

OBJECTIVE

To determine what proportion of blood transfusions given in Mwanza Region, Tanzania could be avoided.

METHODS

A total of 1029 patients who received a blood transfusion in one of eight hospitals were analysed. Two sets of criteria for avoidable blood transfusions were determined, on the basis of a literature review.

RESULTS

The following percentages of blood transfusions in five groups of patients were found to be avoidable: operated patients, 8-24%; pregnant women, 8-10%; children aged under 5 years, 31-52%; children aged 5-14 years, 23-25%; and adults, 16-25%. Overall, 23-39% of blood transfusions were avoidable. At least 75% of all avoidable blood transfusions were to children aged under 5 years.

CONCLUSIONS

The largest reduction of blood transfusions can be achieved in children aged under 5 years, especially in infants aged less than 1 year. Following this study, blood transfusion prescribers drew up provisional guidelines on blood transfusions, which have been introduced in all hospitals in Mwanza Region. An evaluation study has been carried out and is being analysed.

Hepatic lipidosis in pregnant cows on a dairy farm

A syndrome very similar to hepatic lipidosis is described in dairy cows during the dry period. After being sent to pasture the animals did not eat well for undetermined reasons. The disease phenomena were mainly observed in animals carrying twins. At post mortem examination severe falty infiltration was found in the 3 animals made available for post mortem examination. Increase of the energy supply to the dry cows by addition of maize silage to the ration prevented new cases.

Angiographic risk factors of luminal narrowing after coronary balloon angioplasty using balloon measurements to reflect stretch and elastic recoil at the dilation site. The CARPORT Study Group

Because many ongoing clinical restenosis prevention trials are using quantitative angiography to assess whether a drug is capable of reducing the amount of intimal hyperplasia, quantitative angiographic risk factors for angiographic luminal narrowing after balloon angioplasty were determined, including stretch and elastic recoil at the dilatation site. Quantitative analysis was performed on 666 lesions in 575 patients during angioplasty and at 6-month follow-up. Stretch was defined as balloon diameter minus minimal luminal diameter (MLD) before angioplasty/reference diameter, and recoil as balloon diameter minus MLD after angioplasty/reference diameter. Multivariate analysis was used to yield independent risk factors for luminal narrowing at follow-up. Predictors of absolute change in MLD were (1) relative gain at angioplasty (gain in millimeters normalized for reference diameter) and (2) lesion length. To allow risk stratification, logistic regression analysis was applied using the decrease in MLD as a binary outcome variable. A decrease in MLD at follow-up of greater than or equal to 0.72 mm was considered significant. Variables retained in the model were: relative gain greater than 0.3 mm (rate ratio 2.9), relative gain 0.2 to 0.3 (rate ratio 2.1), stenosis length greater than or equal to 6.8 (rate ratio 1.7), and thrombus after angioplasty (rate ratio 2.6). Although stretch was significantly related to luminal narrowing at univariate analysis, it was not retained in the multivariate models. A large gain in lumen diameter at angioplasty, dilation of long lesions, and angiographically determined thrombus after angioplasty were found to be accompanied by more severe luminal narrowing at follow-up.

Determinants for early mortality in patients awaiting coronary artery bypass graft surgery: a case-control study

A total of 1124 consecutive patients who were selected for coronary artery bypass graft surgery were studied. Of patients awaiting surgery (mean waiting time 98 days) 25 patients (2.2%) died before operation (mean waiting time 63 days). To assess patient characteristics predictive for early mortality before surgery, 25 deceased patients were analysed and compared to 50 controls matched for age, gender, type of surgery and waiting-list priority. Univariate analysis showed that the deceased patients had a higher rate of severe angina pectoris class III-IV (odds ratio (OR) 2.9), unstable angina prior to angiography (OR 4.8), cardiac enlargement on chest X-ray (OR 13.5), positive exercise testing of short duration (less than or equal to 6 min) (OR 6.0), coumarin treatment (OR 4.2), smoking (OR 3.0), severe left main or three-vessel disease (OR 4.1), abnormal end-diastolic volume (OR 3.1) and an abnormal left ventricular wall motion score (OR 3.0). Using multivariate analysis, cardiac enlargement (OR 14.4), positive exercise testing of short duration (OR 13.3), smoking (OR 8.7), coumarin treatment (OR 7.1), unstable angina (OR 6.5) and/or left main or three-vessel disease (OR 5.4) were independent predictors for death while awaiting coronary revascularisation. Thus, patients with the above mentioned independent characteristics have an increased short-term mortality while awaiting coronary bypass graft surgery. These indicators may contribute important information for determination of priority in high risk patients awaiting coronary artery bypass graft surgery.

Treatment of uremic anemia with recombinant erythropoietin also reduces the defects in platelet adhesion and aggregation caused by uremic plasma

In the present study, uremic patients on chronic maintenance hemodialysis were treated with recombinant erythropoietin. Before and after 20 weeks of treatment, platelet adhesion and aggregation were studied with perfusions over a sprayed collagen surface and over matrix of cultured endothelial cells with high tissue factor activity. The influence of the erythropoietin induced raise in hematocrit on platelet transport and adhesion was excluded by performing the perfusions at a standard red blood cell concentration. The present study clearly demonstrates that erythropoietin treatment improves platelet adhesion and aggregation in addition to and independent of its effect on the hematocrit. Studies with control platelets resuspended in plasma of untreated patients showed that a uremic plasma factor reduced adhesion and thrombin- and collagen-dependent aggregation. Patient platelets resuspended in control plasma showed no defects. After erythropoietin treatment, the plasma-induced inhibition of adhesion and aggregation had almost completely disappeared from patient plasma. The beneficial effect of the erythropoietin treatment on uremic hemostasis is therefore twofold. The increase of the red blood cell mass improves transport of platelets, and thus adhesion to the vessel wall. The intrinsic defect due to the presence of an inhibitory toxin in uremic plasma is, in large part, corrected. Improved neutralization of uremic toxins by red blood cells or less production of toxins by better oxygenated tissue might play a role in the observed phenomena.

The effects of nisoldipine on the total ischaemic burden: the results of the ROCKET study

This study was designed to examine the effects of nisoldipine (relative to placebo), a new dihydropyridine calcium entry blocking agent, in the treatment of silent ischaemia in conventional doses. A total of 409 patients with proven coronary artery disease were screened and of this 64 had at least six episodes or a total duration of 30 min of ST segment depression (1 mm lasting at least 1 min) over 48 h. Fifty-two patients ultimately completed a randomized double-blind cross-over study comparing nisoldipine 5 mg twice a day, nisoldipine 10 mg daily and placebo. There was a reduction in the ST segment integral and number of episodes of ST segment depression when compared to placebo on treatment with nisoldipine 5 mg twice a day and nisoldipine 10 mg daily. However, the confidence limits were wide and crossed the no-treatment effect line. In addition, the nisoldipine doses neither affected the circadian distribution of ischaemic episodes nor caused an alteration of the workload achieved either at peak exercise or at 1 mm ST segment depression measured 24 h after nisoldipine 10 mg or 12 h after nisoldipine 5 mg. We conclude that frequent silent ischaemia in patients with proven coronary artery disease is relatively uncommon; it accounts for approximately 16% of patients with positive exercise. In these patients nisoldipine, given as 5 mg twice a day and 10 mg daily, showed no significant therapeutic effects, either on the frequency or severity of silent ischaemia. New formulations of slow release nisoldipine are consequently being developed so that a fuller 24 h therapeutic profile may be obtained.