Altered platelet function detected by flow cytometry. Effects of coronary artery disease and age

Platelet activation state and responsiveness to physiological agonists were measured in 65 patients with documented coronary artery disease (54 male and 11 female; mean age, 58 years). Twelve patients (mean age, 52 years), selected at random from the male cohort, were compared with 12 age-matched male control subjects (mean age, 52 years) and with 10 normal, young male subjects (mean age, 25 years). Whole-blood flow cytometry was used to measure platelet activation status ex vivo and platelet responsiveness to physiological agonists in vitro. Peripheral blood samples were analyzed for bound fibrinogen and expression of P-selectin, GPIb, and GPIIb-IIIa at rest and in response to ADP (0.1 to 10 mumol/L) and thrombin (0.02 to 0.32 mu/mL). No significant differences were seen in the basal levels of fibrinogen binding between any of the groups, but P-selectin expression was significantly lower in patients compared with age-matched control subjects (P = .0005). When stimulated with agonists, patients' platelets had significantly decreased fibrinogen binding (P < .03) but no difference in P-selectin expression compared with the age-matched group. Both agonist-induced fibrinogen binding and P-selectin expression were, however, higher in the young subjects compared with either the older control group or the patients (P < .05). GPIb and GPIIb-IIIa expression were lowest in the patients with angina and highest in the young control subjects, with levels in the age-matched control subjects falling between these values. Data from the total patient cohort (n = 65) were identical to those in the smaller cohort (n = 12). In conclusion, atherosclerosis impairs platelet aggregatory responses (fibrinogen binding) over and above the decreased response seen with age. Platelet degranulation (P-selectin expression) is also impaired in patients with coronary artery disease, but only in comparison with younger subjects, not age-matched controls.

Concrete induced cardiac contusion

A previously fit 22 year old man was struck in the chest by a concrete block dropped through the windscreen of his car while he was driving on the motorway. He suffered extensive chest wall trauma and lung contusion, which subsequently precipitated acute respiratory distress. On admission ECG showed right bundle branch block and left axis deviation. Three days later QRS duration was normal but there was anterior ST segment elevation and subsequent T wave change. There was a large rise in creatine kinase, and echocardiography revealed septal and apical hyokinesis as well as a mobile mass attached to the left side of the interventricular septum, which had the echogenic texture of myocardium. The patient had fixed perfusion defects in the areas of hypokinesis on thallium scanning but the coronary arteries were unobstructed at angiography. He was treated with warfarin in the short term and an angiotensin converting enzyme inhibitor in the longer term and has made an asymptomatic recovery. Outpatient echocardiography two months after the injury demonstrated some recovery in overall left ventricular systolic function and no evidence of the intracardiac mass. This case illustrates some of the typical features of non-fatal cardiac contusion associated with non-penetrating cardiac trauma, and was complicated by partial thickness avulsion of a strip of the myocardium in the interventricular septum.

Diagnosis and treatment of the cracked tooth

This review paper discusses the recognised factors which predispose to cracked-tooth syndrome. In addition, common presenting symptoms and the various methods to aid clinical diagnosis of this problem are examined. The incidence of the condition is reported and the prognosis of the various forms of fracture, as suggested by clinical presentation, are outlined with reference to the available literature. Benefits and relative demerits of traditional and more modern treatment options are presented and recommendations made for future research.

Modulation of MHC isoforms in functionally overloaded and exercised rat plantaris fibers

The effects of 1 and 10 wk of functional overload (FO) of the rat plantaris with (FOTr) and without daily endurance treadmill training on its myosin heavy chain (MHC) composition were studied. After 1 and 10 wk of FO, plantaris mass was 22 and 56% greater in FO and 37 and 94% greater, respectively, in FOTr rats compared with age-matched controls. At 1 wk, pure type I and pure type IIa MHC fibers were hypertrophied in FO (39 and 44%) and FOTr (70 and 87%) rats. By 10 wk all fiber types comprising >5% of the fibers sampled showed a hypertrophic response in both FO groups. One week of FO increased the percentage of hybrid (containing both type I and type IIa MHC) fibers and of fibers containing embryonic MHC. By 10 wk, the percentage of pure type I MHC fibers was approximately 40% in both FO groups compared with 15% in controls, and the percentage of fibers containing embryonic MHC was similar to that in controls. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses showed an increase in type I MHC and a decrease in type IIb MHC in both FO groups at 10 wk, whereas little change was observed at 1 wk. These data are consistent with hypertrophy and transformation from faster to slower MHC isoforms in chronically overloaded muscles. The additional overload imposed by daily endurance treadmill training employed in this study (1.6 km/day; 10% incline) results in a larger hypertrophic response but appears to have a minimal effect on the MHC adaptations.

Control of ocular inflammation after cataract extraction with rimexolone 1% ophthalmic suspension

PURPOSE

To assess the efficacy and safety of rimexolone 1% ophthalmic suspension in controlling intraocular inflammation after cataract extraction.

SETTING

Twelve independent investigational centers in the United States

METHODS

This study comprised 197 patients who had cataract extraction. Postoperatively, patients were randomized to a 2 week regimen of rimexolone 1% ophthalmic suspension or a placebo. Efficacy was analyzed by monitoring total anterior chamber cells and flare, other parameters of inflammation, and treatment failures. Safety was evaluated by monitoring treatment-related adverse events and intraocular pressure (IOP).

RESULTS

Rimexolone 1% was clinically and statistically more effective in suppressing cell and flare than the placebo (P < .02). The overall discontinuation rate for treatment-related adverse events was 5.3% in the rimexolone group and 22.2% in the placebo group. There were no between-group differences in IOP.

CONCLUSION

Rimexolone 1% ophthalmic suspension was safe and significantly more effective than a placebo in controlling intraocular inflammation after cataract extraction when used four times daily and continued for 2 weeks.

Physical activity promotion through primary health care in England

BACKGROUND

There is increasing research supporting the argument for a beneficial link between physical activity and health maintenance and, in the past five years, this has led to a growth in physical activity promotion schemes involving primary health care.

AIM

To document and critically examine the extent and nature of physical activity promotion in general practice in England.

METHOD

A postal survey to all family health services authorities and primary care facilitators was conducted to identify existing and planned activity promotion schemes involving primary health care. Telephone interviews with leaders from 50 selected schemes and further detailed case studies of 11 schemes provided descriptive information of the nature of physical activity promotion.

RESULTS

The initial phase revealed 157 existing schemes and a further 35 planned schemes. Two basic models of physical activity promotion were identified that were distinguishable by the primary location of the management of the patient. Practice-managed interventions (32%) involve on-site counselling to change the behaviour of patients. Leisure centre-managed projects (68%), sometimes termed 'exercise by prescription' or 'general practitioner referral for exercise' schemes, involve the identification of suitable patients and their referral to 10- to 12-week-long leisure centre based exercise induction courses. The projects in the planning stage were all of the latter type, indicating this as the favoured model. Although such schemes were generally successful in attracting patients, in all cases they involved less than 1% of the patient base from which they were drawn.

CONCLUSION

There is evidence of successful recruitment, increased short-term physical activity and fitness, and improvements in the well-being of patients. However, schemes are inadequately resourced for rigorous long-term evaluation; therefore, conclusions regarding the cost-effectiveness of the two models are not possible.

Hibernating myocardium: clinical and functional response to revascularisation

OBJECTIVE

We assessed the effects of coronary bypass grafting on left ventricular (LV) function, exercise capacity and symptom profile in patients with LV impairment and evaluated the role of identifying myocardial hibernation in a prospective non-randomised study.

METHODS

Of 120 patients screened, 47 patients with LV ejection fraction < 35% and three vessel coronary artery disease were studied. All underwent stress/redistribution and separate day rest/redistribution T1-201 imaging together with cine MRI at enrolment, and cine MRI at follow-up. Group 1, 30 patients undergoing bypass surgery, underwent symptom limited treadmill exercise testing with peak VO2 measurement, and symptom profile evaluation less than 3 months before, and 3-6 months after operation. Revascularisation was assessed by post-operative T1-201 imaging and repeat coronary angiography. Group 2, 17 patients treated on medical therapy alone underwent symptom profile assessment at enrolment and follow-up for those who survived. Segmental hibernation was defined as the equivalent of greater than 50% of maximal T1-201 uptake where wall motion was severely impaired on resting imaging. Patients were considered to be hibernating where two of nine LV segments fulfilled these criteria.

RESULTS

In group 1, five patients died (17%), peri-or post-operatively, two defaulted and 23 attended follow-up studies. In group 2, three patients died prior to follow-up (18%). In the surgical group there was an increase in mean LVEF from 24.0 +/- 8% to 29.7 +/- 11% (P < 0.05) while in the medical group there was a fall from 25.7 +/- 10% to 20.6 +/- 8% (P < 0.05). In group 1, the mean NYHA dyspnoea grade improved from 2.7 to 1.4 while in the medical group it was unchanged, 2.6 to 2.5. In patients with myocardial hibernation identified pre-operatively, 18/19 (95%) improved LVEF after CABG compared with 2/4 (50%) of patients without hibernation. 17/19 (86%) patients with hibernation improved NYHA dyspnoea class compared with 2/4 (50%) of patients without. 60/93 (65%) of hibernating segments improved function after revascularisation while 47/53 (89%) hibernating segments showed no improvement on medical therapy alone.

CONCLUSION

In patients with severe LV impairment with myocardial hibernation, coronary artery bypass grafting improves both global and regional systolic LV function, and symptom profile. Medical treatment of patients with LV impairment and myocardial hibernation does not improve LV contractile function or symptoms. Both surgical and medical therapy carry a high mortality rate.

Calcium intake and fracture risk: results from the study of osteoporotic fractures

The relation between dietary calcium, calcium, and vitamin D supplements and the risk of fractures of the hip (n = 332), ankle (n = 210), proximal humerus (n = 241), wrist (n = 467), and vertebrae (n = 389) was investigated in a cohort study involving 9,704 US white women aged 65 years or older. Baseline assessments took place in 1986-1988 in four US metropolitan areas. Dietary calcium intake was assessed at baseline with a validated food frequency questionnaire. Data on new nonvertebral fractures were collected every 4 months during a mean of 6.6 years of follow-up; identification of new vertebral fractures was based on comparison of baseline and follow-up radiographs of the spine done a mean of 3.7 years apart. Results were adjusted for numerous potential confounders, including weight, physical activity, estrogen use, protein intake, and history of falls, osteoporosis, and fractures. There were no important associations between dietary calcium intake and the risk of any of the fractures studied. Current use of calcium supplements was associated with increased risk of hip (relative risk = 1.5, 95% confidence interval 1.1-2.0) and vertebral (relative risk = 1.4, 95% confidence interval 1.1-1.9) fractures; current use of Tums antacid tablets was associated with increased risk of fractures of the proximal humerus (relative risk = 1.7, 95% confidence interval 1.3-2.4). There was no evidence of a protective effect of vitamin D supplements. Although a true adverse effect of calcium supplements on fracture risk cannot be ruled out, it is more likely that our findings are due to inadequately controlled confounding by indications for use of supplements. In conclusion, this study did not find a substantial beneficial effect of calcium on fracture risk.

Beta 2-microglobulin removal by synthetic dialysis membranes. Mechanisms and kinetics of the molecule

Beta 2-microglobulin (beta 2-m) accumulation represents a possible complication of long term dialysis. It is therefore important to evaluate the capacity of removal of this molecule from the patient by different dialysis membranes. The present study is aimed at evaluating the mechanisms involved in beta 2-m removal by three different synthetic membranes: a) highly asymmetric hydrophobic polysulfone (Biosulfane, NMC), b) moderately asymmetric and hydrophobic polysulfone (PS600, Fresenius), c) Polyacylonitrile (AN69HF, Hospal). The adsorption capacity and sieving coefficients of the three membranes for native and labeled beta 2-m were studied in vitro utilizing human blood. The amount adsorbed by the membrane was measured by the elution of the molecule obtained with a detergent solution. Clearances, total removal and membrane adsorption were studied in six patients treated in a randomized sequence with the three membranes. For this purpose, plasma and dialysate measurements as well as total collection of spent dialysate and beta 2-m elution from the used dialyzers were carried out. Ex novo generation of beta 2-m did not take place during in vitro circulation. The molecule was removed by the studied membranes both by filtration and adsorption. The Biosulfane membrane removed beta 2-m mostly by adsorption while the PS600 membrane removed beta 2-m almost entirely by filtration. Intermediate behaviour was shown by AN69 membrane. Similar quantities of beta 2-m were removed from the patients with the three membranes. Total removal could only be precisely measured by adding the quantity of beta 2-m eluted from the membrane to the amount recovered in the spent dialysate. Out of total removal, adsorption was more than 90% with Biosulfane, while only 5% with the PS600. These findings contribute to the understanding of the discrepancy found between the clearance measured from the plasma side and that measured from the dialysate side. In conclusion, clearance and sieving measurements for beta 2-m cannot be correctly performed unless the capacity of adsorption of the membrane is taken into account.

Different effects of calcium antagonists, nitrates, and beta-blockers on platelet function. Possible importance for the treatment of unstable angina

BACKGROUND

The three major classes of antianginal drug all inhibit platelet aggregation at high concentrations in vitro, but detecting clinically relevant effects has proved to be more difficult. We used whole-blood flow cytometry, a sensitive method that allows direct measurement of activation antigens on the surface of individual platelets in whole unfixed blood, to evaluate the effect of representative antianginal drugs on platelet function in vivo in healthy volunteers.

METHODS AND RESULTS

The effects of glyceryl trinitrate (GTN), amlodipine, and atenolol were studied in nine normal volunteers. Fibrinogen binding to activated GP IIb/IIIa and expression of P-selectin, GP Ib, and GP IIb/IIIa on the platelet surface were measured. In addition, fibrinogen binding and P-selectin expression were measured in response to ex vivo stimulation with the agonists ADP and thrombin. The three drugs had very different effects on platelets. GTN inhibited platelet fibrinogen binding and expression of P-selectin at rest and in response to agonist stimulation, whereas amlodipine enhanced P-selectin expression and atenolol increased fibrinogen binding in response to agonists. Atenolol did not block the stimulatory effects of epinephrine on ADP-induced platelet activation. GTN neutralized the proactivatory effects of amlodipine, whereas the effects of atenolol and amlodipine were not additive.

CONCLUSIONS

The three main classes of antianginal medication have different and possible clinically relevant effects on platelet behavior in vivo, nitrates causing inhibition of aggregation (fibrinogen binding) and degranulation (P-selectin expression), calcium antagonists enhancing degranulation, and beta-blockers enhancing aggregation.

Putting the heart back into audit

Images

Effects of intermittent androgen suppression on the stem cell composition and the expression of the TRPM-2 (clusterin) gene in the Shionogi carcinoma

The proportion of tumorigenic stem cells and the expression of the apoptosis-related gene, TRPM-2 (clusterin), were studied in populations of Shionogi carcinoma cells subjected to multiple cycles of androgen withdrawal and replacement (intermittent androgen suppression). The parent androgen-dependent cell line was initially transplanted into a male mouse which was castrated when the estimated weight of the resultant tumour became approximately 3 g. After the tumour had regressed to 40% or less of the original weight, it was transplanted into the next non-castrated male. This was repeated for four cycles of transplantation and castration-induced apoptosis before the tumour progressed to an androgen-independent state. The proportion of total stem cells in the tumour, as determined by in vivo limiting dilution assays in male mice, was constant during the first three cycles but increased 15-fold between the third and fourth cycles. In the parent androgen-dependent tumour before androgen ablation, the androgen-independent stem cell population formed 0.8% of the total stem cell compartment. After the fourth cycle this population increased to 47%; a population of similar size (33%, P = 0.8) was found in the androgen-independent recurrent form of the tumour induced by one-time castration. Whether androgen withdrawal therapy was intermittent or continuous, conversion to androgen independence thus occurred when one-third to one-half of the total stem cell compartment was populated by androgen-independent stem cells. The androgen-repressed TRPM-2 (clusterin) gene was actively expressed in regressing tumours after androgen ablation, and also became constitutively expressed in non-regressing tumours after the first and subsequent cycles of androgen withdrawal. Staining of cytoplasm and nuclei with anti-clusterin antibody was observed in androgen-dependent tumour cells after each cycle of intermittent androgen suppression; the nuclear staining was more intense in recurrent androgen-independent cells. The anomalous nuclear localization of clusterin, an anti-cytolytic TRPM-2 encoded protein, may serve to inhibit early events in the apoptotic process and thereby foster the generation and outgrowth of androgen-independent stem cells in an androgen-depleted environment.

Assessing a murmur, saving a life: current trends in the management of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy, formerly called idiopathic hypertrophic subaortic stenosis (IHSS), is the leading cause of sudden cardiac death in young people. Hypertrophic cardiomyopathy is a non-dilated cardiomyopathy primarily affecting the left ventricle, left atria, intraventricular septum, and mitral valve. It is an autosomal dominant genetic disorder that impairs diastolic and systolic function. Diagnosis is complex due to the heterogeneity of the disease. Symptoms and morphology are not always related and clinical signs may be absent or limited to a soft systolic murmur. The first symptom of hypertrophic cardiomyopathy is frequently sudden cardiac death. Echocardiogram is an accurate diagnostic tool. Asymptomatic patients are generally not treated. Treatment for symptomatic patients begins with beta or calcium channel blockers. Antiarrhythmics may be added to protect against sudden cardiac death. Surgical intervention is done if other treatments fall and involves removal of a portion of the obstructive septum. Operative mortality is 5% with a 60% reduction in symptoms. A promising alternative to surgery is dual-chamber pacemakers. Patient and family teaching is the emphasis of long-term management.

Vertical Banded Gastroplasty and Distal Gastric Bypass as Primary Procedures: A Comparison

BACKGROUND: Comparing primary vertical banded gastroplasty (VBG) and distal gastric bypass (DGBP) patients might assist decision-making based on patient profiles and desired outcomes. METHODS: A prospective study of 81 vertical banded gastroplasty and 60 distal gastric bypass patients. Technical aspects, complications, weight loss, post-op compliance and satisfaction are reported. Length of follow-up is 48 months (VBG) and 36 (DGBP). Lost-to-follow-up 41% (VBG) and 22% (DGBP). Ten per cent of VBGs were revised, with 1% takedown. Three percent DGBPs were converted to proximal GBPs. Demographics are comparable. RESULTS: Operative time was 40 min VBG and 88 DGBP; blood loss 187 cc vs 335 cc; and hospital stay 3 versus 4 days. Exclusive VBG complications include: 1% staple-line leak, 4% intra-abdominal abscess, 1% respiratory failure, 5% pneumonia, 1% intra-abdominal bleed, 1% small bowel obstruction, 2% infected incision, 2% fistula, 2% stenotic or obstructed obstructed stoma, and 1% bezoar. Exclusive DGBP complications include: 2% GI bleed, 12% marginal ulcer, 5% reflux esophagitis, 13% hypocalcemia, 23% hypovitaminosis A and D (12% requiring B12 therapy). Shared complications include hypoproteinemia 6% VBG versus 40% DGBP; excess vomiting (>6 months post-op), 7% versus 10%, excess diarrhea 2% versus 20%, dehydration 1% versus 8%, re-hospitalization 4% versus 15% (hyperalimentation), post-op cholecystectomy 1% versus 5%, weight regain 48% versus 1%. VBG experienced an average of 64% excess weight loss at 36 months versus DGBP 89% excess weight loss. VBG follow-up compliance is generally poor but good for DGBP. Compliance with diet and supplements is equivalent (50%). Satisfaction is 85% and 93% respectively. CONCLUSION: The DGBP provides better long-term weight loss, but nutritional deficiencies occur more often and require close follow-up. The surgery is more complex, but as a primary procedure there are few major complications.

Relationship between donor/recipient lung size mismatch and functional outcome in single lung transplantation for COPD

Single lung transplantation is an effective treatment for patients with severe chronic obstructive pulmonary disease. Pulmonary hyperinflation, which is seen in most patients with severe chronic obstructive pulmonary disease, makes the task of appropriately matching the donor and recipient difficult. It seems that the optimal matching strategy remains undefined. No correlation between donor/recipient size match (actual and predicted) and the degree of functional improvement after single lung transplantation was found. There were no significant differences noted when comparing the functional outcomes of right and left lung transplant recipients. It was concluded that the chronic hyperinflation associated with severe chronic obstructive pulmonary disease allows for the use of significantly larger donors. The use of expanded donor/recipient size match criteria in patients with severe chronic obstructive pulmonary disease may shorten the waiting period prior to single lung transplantation and provide better utilization of donor organs.

Absolute identification of muramic acid, at trace levels, in human septic synovial fluids in vivo and absence in aseptic fluids

This is the first report of a study employing the state-of-the-art technique of gas chromatography-tandem mass spectrometry for absolute identification of muramic acid (a marker for peptidoglycan) at trace levels in a human or animal body fluid or tissue. Daughter mass spectra of synovial fluid muramic acid peaks (> or = 30 ng/ml) were identical to those of pure muramic acid. Absolute chemical identification at this level represents a 1,000-fold increase in sensitivity over previous gas chromatography-mass spectrometry identifications. Muramic acid was positively identified in synovial fluids during infection and was eliminated over time but was absent from aseptic fluids.

Registration of births, stillbirths and infant deaths in Jamaica

BACKGROUND

Vital statistics underestimate the prevalence of perinatal and infant deaths. This is particularly significant when these parameters affect eligibility for international assistance for newly emerging nations.

OBJECTIVE

To determine the level of registration of livebirths, stillbirths and infant deaths in Jamaica.

METHODOLOGY

Births, stillbirths and neonatal deaths identified during a cross-sectional study (1986); and infant deaths identified in six parishes (1993) were matched to vital registration documents filed with the Registrar General.

RESULTS

While 94% of livebirths were registered by one year of age (1986), only 13% of stillbirths (1986) and 25% of infant deaths (1993) were registered. Post neonatal deaths were more likely to be registered than early neonatal deaths. Frequently the birth was not registered when the infant died. Birth registration rates were highest in parishes with high rates of hospital deliveries (rs = 0.97, P < 0.001) where institutions notify the registrar of each birth. Hospital deaths, however, were less likely to be registered than community deaths as registrars are not automatically notified of these deaths.

CONCLUSIONS

To improve vital registration, institutions should become registration centres for all vital events occurring there (births, stillbirths, deaths). Recommendations aimed at modernizing the vital registration system in Jamaica and other developing countries are also made.

Women with chest pain: is exercise testing worthwhile?

OBJECTIVE

To determine the diagnostic value of the exercise tolerance test (ETT) in women presenting with chest pain.

DESIGN

Prospective study of all women presenting to a centre with chest pain between 1987 and 1993 who were assessed by an ETT and coronary angiography.

SETTING

The outpatient clinic of one consultant cardiologist in a tertiary referral centre.

PATIENTS

All women referred to this outpatient clinic with chest pain were screened. For inclusion, patients had to perform ETT and undergo coronary angiography. Of the 347 referred during this period, 142 were excluded because they were unable to perform ETT or because of Q waves or other abnormalities on their resting electrocardiogram.

RESULTS

Overall the sensitivity of the ETT was 68% and the specificity was 61%, with a positive predictive value of 0.61 and a negative predictive value of 0.68. There were 42 false positive and 31 false negative ETT results (36% of the study group). The predictive value of a negative test was higher in younger women (< 52 years) than in the older group (> or = 52 years) (P = 0.004), but the positive predictive value in the two groups was not significantly different. The predictive value of a negative test was also higher in those with two or fewer risk factors than in those with three or more risk factors (P = 0.001). The negative predictive value for those women above 52 years with three or more risk factors (24% of the study group) was only 0.25. Lack of chest pain during ETT was associated with a higher negative predictive value in the younger group than in the older women (P = 0.006).

CONCLUSIONS

In women with chest pain use of the ETT was a misleading predictor of the presence or absence of coronary disease in 36% of these patients. In particular, a negative test in older women with three or more risk factors had a very low predictive value. The inclusion of risk factors and division by age can, however, be used to identify a population at intermediate risk for coronary artery disease in whom the ETT result has the highest diagnostic utility.

Tenuous link between ischaemic threshold and both ambulatory ischaemia and symptom status over time in stable angina: a 5-year follow-up study

This study evaluates changes in ischaemic threshold over a 5-year period in patients with stable angina pectoris, who did not suffer any intervening cardiac event. Changes in ischaemic threshold are related to alterations in symptomatic status and ambulatory ischaemia. Over long-term follow-up, there is a significant fall in ischaemic threshold in such patients (mean heart rate at onset of ischaemia fell from 104 +/- 17.8 to 97 +/- 17.4 bpm: P < 0.001), but this is not matched by a worsening of either symptoms or ischaemia during daily life. In the 68% of patients that had a reduction in ischaemic threshold of > or = 5 bpm, 68% had either definite reduction or no change in symptoms and 84% had either reduction, abolition or no change in transient ischaemic activity. The dissociation between ischaemic threshold, ambulatory ischaemia and symptoms has implications for long-term monitoring and management of the patient with stable angina.

Glutamate receptor blockade at cortical synapses disrupts development of thalamocortical and columnar organization in somatosensory cortex

The segregation of thalamocortical inputs into eye-specific stripes in the developing cat or monkey visual cortex is prevented by manipulations that perturb or abolish neural activity in the visual pathway. Such findings show that proper development of the functional organization of visual cortex is dependent on normal patterns of neural activity. The generalisation of this conclusion to other sensory cortices has been questioned by findings that the segregation of thalamocortical afferents into a somatotopic barrel pattern in developing rodent primary somatosensory cortex (S1) is not prevented by activity blockade. We show that a temporary block of N-methyl-D-aspartate (NMDA) and non-NMDA glutamate receptors in rat S1 during the critical period for barrel development disrupts the topographic refinement of thalamocortical connectivity and columnar organization. These effects are evident well after the blockade is ineffective and thus may be permanent. Our findings show that neural activity and specifically the activation of postsynaptic cortical neurons has a prominent role in establishing the primary sensory map in S1, as well as the topographic organization of higher order synaptic connections.