Patella malalignment, pain and patellofemoral progression: the Health ABC Study

OBJECTIVE

Patellofemoral (PF) joint osteoarthritis (OA) is strongly correlated with lower extremity disability and knee pain. Risk factors for pain and structural progression in PF OA are poorly understood. Our objective was to determine the association between patella malalignment and its relation to pain severity, and PF OA disease progression.

METHODS

We conducted an analysis of data from the Health ABC knee OA study. Health ABC is a community based, multi-center cohort study of 3075 Caucasian and Black men and women aged 70-79 at enrollment. Weight bearing skyline knee X-rays were obtained in a subset (595) of subjects, with and without knee pain, at year 2 and year 5 (mean follow-up 36 months). Films were read paired, and PF osteophytes (OST) and joint space narrowing (JSN) were scored on a 0-3 scale using the Osteoarthritis Research Society International atlas. We defined progression of PF OA as any increase in JSN score. Three measures of patella malalignment were made: sulcus angle; patella tilt angle; and patella subluxation medially or laterally (bisect offset). Knee symptoms were assessed using a knee specific Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) knee pain subscale. We assessed the relationship between baseline patella malalignment and pain severity (linear regression for WOMAC) and compartment specific PF OA progression (logistic regression for dichotomous outcomes). We classified continuous measures of patella alignment into quartile groups. We performed multivariable adjusted logistic regression models, including age, gender and body mass index (BMI) to assess the relation of baseline patella alignment to the occurrence of PF JSN progression using generalized estimating equations (GEE).

RESULTS

The subjects had a mean age 73.6 (SD 2.9), BMI 28.8 (SD 4.9), 40.3% male, and 46% were Black. Medial displacement of the patella predisposed to medial JSN progression; odds for each quartile 1, 1.2, 1.2, 2.2 (P for trend=0.03), whilst protecting from lateral JSN progression; odds for each quartile 1, 0.7, 0.6, 0.4 (P for trend=0.0004). Increasing patella tilt protected from medial JSN progression; odds for each quartile 1, 0.8, 0.5, 0.2 (P<0.0001) and trended to increasing pain severity (P=0.09).

CONCLUSION

Patella malalignment is associated with PF disease progression. Medial displacement and tilt of the patella predisposes to medial JSN progression, whilst lateral displacement is predictive of lateral JSN progression. The influence of patella malalignment has important implications since it is potentially modifiable through footwear, taping and/or knee bracing.

Polymorphisms of angiotensinogen and angiotensin-converting enzyme associated with lower extremity arterial disease in the Health, Aging and Body Composition study

The role of renin-angiotensin system (RAS) genes on the risk of lower extremity arterial disease (LEAD) in elderly people remains unclear. We assessed the relationship of genetic polymorphisms in RAS: G-6A, T174M and M235T of the angiotensinogen (AGT) gene, and the angiotensin-converting enzyme insertion/deletion (ACE_I/D) variant to the risk of LEAD in the Health, Aging and Body Composition (Health ABC) Study. This analysis included 1228 black and 1306 white men and women whose age ranged between 70 and 79 years at the study enrollment. LEAD was defined as ankle-arm index (AAI) <0.9. Genotype-phenotype associations were estimated by regression analyses with and without adjustment for established cardiovascular disease (CVD) risk factors. The proportion of LEAD was significantly higher in black (21.1%) than that in white elderly people (10.1%, P<0.0001). The distribution of AGT polymorphisms was also significantly different between black and white participants. There was no statistically significant association between the selected RAS genetic variants and LEAD after adjustment for age, antihypertensive medications, lipid-lowering medication, pack-year smoking, body mass index, low-density lipoprotein cholesterol, and prevalent diabetes and coronary heart disease. However, A-T haplotype of G-6A and M235T interacting with homozygous ACE_II (beta=-1.07, P=0.006) and with ACE inhibitors (beta=-1.03, P=0.01) significantly decreased the risk of LEAD in white but not in black participants after adjustment for the selected CVD risk factors. In conclusion, the study observed a gene-gene and gene-drug interaction for LEAD in the white elderly.

PPAR-gamma Pro12Ala genotype and risk of cognitive decline in elders

BACKGROUND

The Pro12Ala polymorphism of peroxisome proliferator-activated receptor-gamma (PPAR-gamma) has been associated with decreased risk of diabetes and obesity, both disorders linked to cognitive impairment. We tested whether this polymorphism is associated with cognition.

METHODS

Two thousand nine hundred sixty-one participants (mean age, 74.1; 41% Black; 52% women) were administered the Modified Mini-Mental State Examination (3MS) and Digit Symbol Substitution Test (DSST) at baseline and 4 year follow-up. Test scores were adjusted for age, sex, education, cerebrovascular disease, depression and APOE genotype and additionally for race. We determined the association between Ala allele and development of cognitive decline (3MS decline of > or = 5 points).

RESULTS

At baseline, unadjusted scores on both cognitive tests were higher for Ala carriers compared to non-carriers (3MS, 94.2 versus 92.5, p<0.001; DSST, 40.2 versus 34.5, p<0.001). Similarly, follow-up scores were higher for Ala carriers. Multivariable adjustment led to similar results; additional adjustment for race attenuated the baseline 3MS results. After 4 years, 17.5% of Ala carriers developed cognitive decline compared to 25% among non-carriers (unadjusted OR=0.61; 95%CI, 0.46-0.82; adjusted OR=0.75; 95%CI, 0.55-1.02). Further adjustment for metabolic variables including fasting blood glucose and lipid level did not change the results.

CONCLUSIONS

The PPAR-gamma Ala12 allele carriers may have less risk of developing cognitive decline.

Authorship of research papers: ethical and professional issues for short-term researchers

Although the International Committee of Medical Journal Editors has published clear guidance on the authorship of scientific papers, short-term contract research workers, who perform much of the research that is reported in the biomedical literature, are often at a disadvantage in terms of recognition, reward and career progression. This article identifies several professional, ethical and operational issues associated with the assignment of authorship, describes how a university department of primary care set about identifying and responding to the concerns of its contract research staff on authorship and describes a set of guidelines that were produced to deal with the ethical and professional issues raised. These guidelines include directions on how authorship should be negotiated and allocated and how short-term researchers can begin to develop as authors. They also deal with the structures required to support an equitable system, which deals with the needs of short-term researchers in ways that are realistic in the increasingly competitive world of research funding and publication, and may offer a model for more formal guidelines that could form part of institutional research policy.

Seismology: tectonic strain in plate interiors?

It is not fully understood how or why the inner areas of tectonic plates deform, leading to large, although infrequent, earthquakes. Smalley et al. offer a potential breakthrough by suggesting that surface deformation in the central United States accumulates at rates comparable to those across plate boundaries. However, we find no statistically significant deformation in three independent analyses of the data set used by Smalley et al., and conclude therefore that only the upper bounds of magnitude and repeat time for large earthquakes can be inferred at present.

Morphometric analysis of gray matter volume in demented older adults: exploratory analysis of the cardiovascular health study brain MRI database

We tested the feasibility of a fully automated brain MRI voxel count technique--automated labeling pathway (ALP)--in a sample of 15 demented and 13 cognitively normal women (age 75-85 years) participating to the Cardiovascular Health Study (CHS). We hypothesized that ALP would replicate well-established findings of the anatomical correlates of dementia. In particular, we hypothesized that ALP volumetric measures would: (1) significantly differ between cognitively normal and demented women in those brain areas that are established markers for diagnosis of dementia (temporal and medial temporal lobes, hippocampus, amygdala and parahippocampus) but not in other brain areas (e.g., occipital lobe, visual cortex, motor cortex) and (2) correlate with visual ratings of brain disease which have been previously collected as part of the CHS. ALP required minimal operator intervention (input of brain images and verification of misalignments) and employed computer time of about 1 h per brain. ALP detected significant focal volumetric differences in the limbic system (p values between groups for hippocampus and parahippocampus: 0.002 and 0.005, respectively), temporal lobe (p < 0.0001) and caudate (p = 0.009), but not in other brain areas (e.g. occipital lobe, visual or motor cortex). Furthermore, ALP measures of medial temporal lobe atrophy strongly correlated with CHS visual ratings of ventricular enlargement (r(2) = 0.6, p = 0.002 for medial temporal lobe). In conclusion, ALP-detected focal brain atrophy was strongly associated with dementia. Because of its fully automated design, ALP technique is an ideal candidate to assess whether volumetric measures of specific areas can discriminate dementia better than currently available measures of global brain atrophy in large epidemiological studies.

Bilingual young people's experiences of interpreting in primary care: a qualitative study

BACKGROUND

Young people are often used as interpreters for family members in the primary healthcare setting.

AIM

To explore bilingual young people's accounts of interpreting for family or friends in primary care settings.

DESIGN OF STUDY

Qualitative study using in-depth interviews.

SETTING

Community and youth groups in London.

METHODS

Young people aged nine to 18 years old (n = 77) were purposively sampled to include those from established and recently arrived groups and were from Vietnamese, Kurdish, Bangladeshi or Eastern European backgrounds. Participants were interviewed one-to-one or with a friend, and interview transcripts were analysed to identify key themes.

RESULTS

Young people were used for interpreting because of deficiencies in services, and also by choice. They identified advantages and disadvantages in their experiences. The majority of healthcare encounters were regarded as unproblematic. Three factors contributed to less successful encounters: healthcare professionals' or patients' communication skills; young people's own language skills, and the nature of the healthcare problem.

CONCLUSION

This study identifies ways in which primary care professionals could facilitate better communication in encounters where young people are used as interpreters.

Differing effects of low-dose estrogen-progestin therapy and pravastatin in postmenopausal hypercholesterolemic women

BACKGROUND

Most studies examining the potential cardioprotective effects of postmenopausal estrogen have been undertaken in healthy women, with doses that may not be appropriate for long-term intervention. New low-dose estrogen-progestin regimens alleviate postmenopausal symptoms with a favorable side-effect profile; however, little is known of the impact of such regimens in women at increased risk of cardiovascular disease. Hence, we have evaluated the effects of low-dose oral estrogen-progestin therapy on serum lipoprotein lipids, brachial artery reactivity and fibrinogen in hypercholesterolemic postmenopausal women in direct comparison with the effects of pravastatin, a lipid-lowering agent known to reduce cardiovascular events in women.

METHODS

In a randomized, double-blind, double-dummy, parallel trial, we studied the effects of continuous combined estrogen-progestin therapy (1 mg 17beta-estradiol with 500 micro g norethisterone acetate daily) or pravastatin (20 mg daily) in 72 postmenopausal women with fasting serum low-density lipoprotein (LDL) cholesterol levels greater than 124 mg/dl after an 8-week run-in diet, over a 24-week period. The primary end-point was percentage change in LDL cholesterol from baseline.

RESULTS

The intention-to-treat population comprised 65 women, mean age 59 +/- 6.3 years, and 29 in each group completed the trial. Diet alone reduced LDL cholesterol significantly in both treatment groups, in association with a reduction in weight during this period. Compared with respective baseline values, pravastatin decreased LDL cholesterol and total cholesterol to a greater extent than hormone therapy (p = 0.0001 and 0.003 for difference between treatments, respectively). High-density lipoprotein (HDL) cholesterol levels decreased with hormone therapy, but did not change with pravastatin (p = 0.01). Lipoprotein(a) decreased significantly with hormone therapy only (-14%, 95% confidence interval (CI) -21 to -6%, p = 0.01 for difference between groups). Brachial artery flow-mediated dilatation (FMD) was impaired at baseline, and this increased with hormone therapy (absolute mean change in artery diameter as percentage units 2.07, 95% CI 0.57-3.57, p = 0.009) versus no change with pravastatin (0.19, 95% CI -1.1 to 1.5, p = 0.78), with a near-significant difference between the two groups (p = 0.058). A significant correlation between improved brachial artery FMD and reduction in LDL cholesterol was not observed. Fibrinogen decreased significantly in both treatment groups with no difference between treatments.

CONCLUSIONS

In postmenopausal hypercholesterolemic women, pravastatin and hormone therapy exhibited divergent effects. The former lowered total and LDL cholesterol more effectively, whereas hormone therapy lowered lipoprotein(a) significantly and improved brachial artery endothelium-dependent dilatation, independent of the reduction in LDL cholesterol. The modest increase in brachial artery FMD seen is consistent with hypercholesterolemia compromising endothelial integrity, and suggests that the important effect of estrogen on the endothelial microenvironment may be attenuated in women with endothelial dysfunction.

Aortic stiffness is associated with visceral adiposity in older adults enrolled in the study of health, aging, and body composition

The central arteries stiffen with age, causing hemodynamic alterations that have been associated with cardiovascular events. Changes in body fat with age may be related to aortic stiffening. The association between vascular stiffness and body fat was evaluated in 2488 older adults (mean age, 74 years; 52% female; 40% black) enrolled in the Study of Health, Aging, and Body Composition (Health ABC), a prospective study of changes in weight and body composition. Clinical sites were located in Pittsburgh, Pa, and Memphis, Tenn. Aortic pulse wave velocity was used as an indirect measure of aortic stiffness. A faster pulse wave velocity indicates a stiffer aorta. Body fat measures were evaluated with dual energy x-ray absorptiometry and computed tomography. Independent of age and blood pressure, pulse wave velocity was positively associated with weight, abdominal circumference, abdominal subcutaneous fat, abdominal visceral fat, thigh fat area, and total fat (P<0.001 for all). The strongest association was with abdominal visceral fat. Elevated pulse wave velocity was also positively associated with history of diabetes and higher levels of glucose, insulin, and hemoglobin A1c (P<0.001 for all). In multivariate analysis, independent positive associations with pulse wave velocity were found for age, systolic blood pressure, heart rate, abdominal visceral fat, smoking, hemoglobin A1c, and history of hypertension. The association between pulse wave velocity and abdominal visceral fat was consistent across tertiles of body weight. Among older adults, higher levels of visceral fat are associated with greater aortic stiffness as measured by pulse wave velocity.

The eating attitudes test: twenty-five years later

This manuscript reviews the literature involved with the Eating Attitudes Test (EAT), first developed in the late 1970s as a self-report, indicative of the symptoms of eating disorders. The EAT has good psychometric properties of reliability and validity, and reasonable sensitivity and specificity for the eating disorders, but very low positive predictive value because eating disorders are relatively uncommon. In addition they exist on a continuum, because of denial and social desirability, the results of a self-report instrument may be affected. A very large literature has documented the use of the EAT in a variety of cultures. It is used to screen eating disturbances in general as the first part of a two-part diagnostic screen, as an ability to compare across groups and to measure change between groups and over time.

Factors associated with healthy aging: the cardiovascular health study

OBJECTIVES

To identify factors associated with remaining healthy in older adults.

DESIGN

Longitudinal cohort study.

SETTING

Data were collected at the four Cardiovascular Health Study field centers.

PARTICIPANTS

5,888 participants age 65 years and older in the Cardiovascular Health Study.

MEASUREMENTS

Presence of chronic disease was assessed at baseline and over a maximum 7-year follow-up period. Participants who were free of chronic disease (no cardiovascular disease (CVD), chronic obstructive pulmonary disease, or self-reported cancer, except nonmelanoma skin cancer) at the baseline examination were then monitored for the onset of incident cancer, cardiovascular disease, and fatal outcomes.

RESULTS

A high proportion of these older adults was healthy at the initial examination and remained healthy over the follow-up period. Numerous behavioral factors were associated with continued health, including physical activity, refraining from cigarette smoking, wine consumption (women), higher educational status, and lower waist circumference. A number of CVD risk factors and subclinical disease measures were associated with continued health, including higher high-density lipoprotein (HDL) cholesterol, lack of diabetes, thinner common carotid intimal nmedial thickness, lower blood pressure, lower C-reactive protein, and higher ankle-arm blood pressure ratio. Among the behavioral factors, exercise, not smoking, and not taking aspirin remained significant predictors of health even after controlling for CVD risk factors and subclinical disease in older adults.

CONCLUSIONS

These data suggest that a number of modifiable behavioral factors (physical activity, smoking, and obesity) and cardiovascular risk factors (diabetes, HDL cholesterol, and blood pressure) are associated with maintenance of good health in older adults.

Medial exposure for dissection of the cranial nerves in situ by medical students

In this article, we illustrate and briefly describe a medial approach, in the sagittally sectioned preserved human head, to display all of the cranial nerves, in situ and in continuity. The method has been successfully used by more than six cohorts of our second-year medical students, and can be completed within a 90-min dissecting session.

Cognitive test performance and presence of subclinical cardiovascular disease in the cardiovascular health study

The purpose of the present study was to investigate the relationship between performance on a comprehensive battery of neuropsychological tests and the presence of clinical, subclinical or no cardiovascular disease in an elderly community-dwelling population. The results confirm previous reports of significant associations of age, education and gender with test performance. When performance was examined controlling for these variables, significant associations of disease group were seen with five measures emphasizing speed of performance; Parts A and B of the Trail Making Test, the WAIS-R Digit Symbol and Block Design subtests and category verbal fluency. These results add to the evidence that, in addition to other health implications, cardiovascular disease is related to cognitive functioning in the elderly even at subclinical levels.

Management and outcome of persistent or recurrent fever after initial intravenous gamma globulin therapy in acute Kawasaki disease

OBJECTIVE

To determine differences in clinical characteristics, laboratory findings, and cardiac complications between patients with acute Kawasaki disease who received additional treatment for persistent or recurrent fever vs those who did not.

DESIGN

Nonconcurrent case series; medical record review.

SETTING

Tertiary care pediatric hospital.

PATIENTS

One hundred eighty-five consecutive patients diagnosed as having acute Kawasaki disease at The Hospital for Sick Children, Toronto, Ontario, from 1995 to 1997.

MAIN OUTCOME MEASURE

Prevalence of cardiac complications.

RESULTS

Twenty-one patients (11%) received additional treatment with intravenous gamma globulin (IVGG) with or without intravenous methylprednisolone for persistent fever lasting for more than 48 hours or recurrent fever after initial treatment with IVGG. Patients who received additional treatment did not differ significantly from other patients regarding age, sex, race, or diagnostic criteria. Compared with the patients who did not receive additional therapy, the patients who received additional treatment had shorter median interval from fever onset to initial dose of IVGG (5 vs 6 days; P=.006) and longer total days of fever (9 vs 6 days; P<.001). Initial laboratory investigations did not differ significantly. On initial echocardiography, patients who received additional therapy were significantly more likely to have pericardial effusion (33% vs 15%; P=.04), ventricular dysfunction (14% vs 2%; P= .002), and coronary artery ectasia (76% vs 43%; P=.004) but not aneurysms (10% vs 5%; P= .47). At 12 months after diagnosis, there were no significant differences between the 2 groups regarding the prevalence of coronary artery ectasia or aneurysms.

CONCLUSION

Patients receiving additional treatment for persistent or recurrent fever have similar demographic and clinical characteristics, greater initial cardiac involvement, and similar overall outcomes.

Recognition and management of Kawasaki disease

Kawasaki disease is the leading cause of acquired heart disease in children in the developed world, with coronary artery aneurysms occurring in up to 25% of untreated cases. The mean annual incidence of Kawasaki disease across Canada is about 13 per 100,000 children less than 5 years of age, based on hospital discharge data from 1990 to 1995. The cause remains unknown, and the diagnosis is based on the same clinical criteria used to describe the disease over 30 years ago. However, nonspecific clinical features, evolving presentations and atypical or incomplete presentations make early diagnosis and timely treatment difficult. Delays in diagnosis and treatment, which occur more frequently in older children, are associated with an increased risk of coronary artery aneurysms. Hence, high diagnostic suspicion and prompt referral are required to reduce the rate of cardiac complications.

BIRICODAR (VX-710; Incel): an effective chemosensitizer in neuroblastoma

Clinical studies have suggested that both MDR1 and MRP may play a significant role in the chemosensitivity and outcome of neuroblastoma. To clarify the nature of multidrug resistance (MDR) in this tumour a series of six neuroblastoma cell lines have been characterized with regard to P-glycoprotein, MRP and LRP expression using immunocytochemistry and expression of MDR1, MRP, LRP and topoisomerase II genes using reverse transcription polymerase chain reaction (RT-PCR). By RT-PCR, all lines expressed MRP, five expressed LRP and four expressed MDR1, but protein levels of each of these were variable. Chemosensitization to a range of MDR-associated drugs (vincristine, doxorubicin, etoposide, taxotere, topotecan) and non-MDR-associated drugs (cisplatin, melphalan) by three modulating agents, cyclosporin A, PSC 833 and the novel Biricodar (VX-710; Incel), was evaluated using a colourimetric cytotoxicity assay (MTS). Alteration of daunorubicin efflux by these agents was evaluated using FACS analysis. Clonogenic assay was used to study the influence of these chemosensitizers on vincristine cytotoxicity. Marked sensitization to vincristine was observed in MDR1-positive lines, and a similar but less consistent effect was seen with taxotere, doxorubicin and etoposide. With MRP-positive, MDR-negative lines, only VX-710 caused consistent sensitization. These data confirm MDR1 and MRP expression as contributory factors in chemoresistance in neuroblastoma and indicate that VX-710 may be a useful modulator of both mechanisms and worthy of clinical evaluation in this tumour.

Slow deformation and lower seismic hazard at the new madrid seismic zone

Global Positioning System (GPS) measurements across the New Madrid seismic zone (NMSZ) in the central United States show little, if any, motion. These data are consistent with platewide continuous GPS data away from the NMSZ, which show no motion within uncertainties. Both these data and the frequency-magnitude relation for seismicity imply that had the largest shocks in the series of earthquakes that occurred in 1811 and 1812 been magnitude 8, their recurrence interval should well exceed 2500 years, longer than has been assumed. Alternatively, the largest 1811 and 1812 earthquakes and those in the paleoseismic record may have been much smaller than typically assumed. Hence, the hazard posed by great earthquakes in the NMSZ appears to be overestimated.

Involvement of protein kinase C and protein kinase A in the muscarinic receptor signalling pathways mediating phospholipase C activation, arachidonic acid release and calcium mobilisation

The involvement of protein kinase C (PKC) and protein kinase A (PKA) in cholinergic signalling in CHO cells expressing the M3 subtype of the muscarinic acetylcholine receptor was examined. Muscarinic signalling was assessed by measuring carbachol-induced activation of phospholipase C (PLC), arachidonic acid release, and calcium mobilisation. Carbachol activation of PLC was not altered by inhibition of PKC with chelerythrine chloride, bisindolylmaleimide or chronic treatment with phorbol myristate acetate (PMA). Activation of PKC by acute treatment with PMA was similarly without effect. In contrast, inhibition of PKC blocked carbachol stimulation of arachidonic acid release. Likewise, PKC inhibition resulted in a decreased ability of carbachol to mobilise calcium, whereas PKC activation potentiated calcium mobilisation. Inhibition of PKA with H89 or Rp-cAMP did not alter the ability of carbachol to activate PLC. Similarly, PKA activation with Sp-cAMP or forskolin had no effect on PLC stimulation by carbachol. Carbachol-mediated release of arachidonic acid was decreased by H89 but only slightly increased by forskolin. Forskolin also increased calcium mobilisation by carbachol. These results suggest a function for PKC and PKA in M3 stimulation of arachidonic acid release and calcium mobilisation but not in PLC activation.

Inhibitory effect of simvastatin on the proliferation of human myeloid leukaemia cells in severe combined immunodeficient (SCID) mice

SCID mice were inoculated intravenously with cells from the human HL60 myeloblastic leukaemia cell line and then treated with the 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitor, simvastatin, by subcutaneous continuous infusion. The effect of the drug was measured by subsequent colony formation of surviving HL60 cells in vitro and flow cytometry. The number of clonogenic HL60 cells was reduced in the bone marrow of mice that received simvastatin compared with control mice by 65% and 68% in two separate experiments. The number of clonogenic, normal, murine, bone marrow progenitor cells concomitantly exposed to simvastatin in vivo, was not affected in either experiment. Flow cytometric analysis of bone marrow and spleen cells confirmed these results by showing that simvastatin had reduced the percentage of human leukaemia cells in these tissues by 70% and 88% respectively. The data show that the reported selective effect of simvastatin against acute myeloid leukaemia cells in vitro, can be extended to this in vivo model. HL60 bears an N-ras mutation. In further in vitro studies, ketoconazole, an inhibitor of cholesterol biosynthesis post farnesyl pyrophosphate synthesis, had a similar effect to simvastatin on HL60 colony development. Furthermore, the clonogenicity of a population of N-ras mutated, primary acute myeloid leukaemia (AML) cells was no more sensitive to simvastatin than a population without the mutation. The data suggest that the inhibition of AML cell proliferation by simvastatin may be independent of the RAS signalling pathway.

Motion detection and directional tuning

A random dot pattern was presented which made two jumps in various directions with a variable delay between them. The jumps occurred at the frame transitions of a 3-frame apparent motion sequence. The variation in detectability with the directional difference and the temporal separation of the jumps allows us to make inferences about directional tuning and the temporal response of the motion detection mechanism. The detectability of a pair of jumps was highest when the delay between the jumps was short and the difference in the jump directions was small. In all cases the data were well fitted with a vector version of the speed energy model earlier proposed by Simpson. The model supposes that the two input vectors are temporally filtered, squared and integrated. Using the model, the autocorrelation function of the motion system's temporal impulse response can be found. This function shows the filter to be lowpass. According to the model, the shape of the threshold or d' locus as a function of the difference in the directions of the two jumps does not show the tuning of a motion mechanism. A tuned mechanism will respond well to a jump in its preferred direction, but less well to any other jump. Instead we show that the apparent tuning evident in the threshold and d' loci is due to the way in which the two jump vectors, each fully recovered, are combined in a vector sum.

Aspirin use and incident stroke in the cardiovascular health study. CHS Collaborative Research Group

BACKGROUND AND PURPOSE

Randomized clinical trials testing aspirin in relatively low-risk, middle-aged people have consistently shown small increases in stroke associated with aspirin use. We analyzed the relationship between the regular use of aspirin and incident ischemic and hemorrhagic stroke among people aged 65 years or older participating in the Cardiovascular Health Study.

METHODS

We conducted a multivariate analysis of incident stroke rates in a prospectively assessed, observational cohort of 5011 elderly people followed for a mean of 4.2 years.

RESULTS

Participants had a mean age of 72 years, and 58% were women. Twenty-three percent used aspirin frequently, and 17% used aspirin infrequently at study entry. Frequent aspirin use was associated with an increased rate of ischemic stroke compared with nonusers (relative risk= 1.6; 95% confidence interval [CI], 1.2 to 2.2; P=0.001). After adjustment for other stroke risk factors, women who used aspirin frequently or infrequently at study entry had a 1.8-fold (95% CI, 1.2 to 2.8) and 1.6-fold (95% CI, 0.9 to 3.0) increased risk of ischemic stroke, respectively (P<0.01, test for trend), compared with nonusers. In men, aspirin use was not statistically significantly associated with stroke risk. Findings were similar when aspirin use in the years before the incident stroke was used in the modeling. Aspirin use at entry was also associated with a 4-fold (95% CI, 1.6 to 10.0) increase in risk of hemorrhagic stroke for both infrequent and frequent users of aspirin (P=0.003).

CONCLUSIONS

Aspirin use was associated with increased risks of ischemic stroke in women and hemorrhagic stroke overall in this elderly cohort, after adjustment for other stroke predictors. The possibility exists of confounding by reasons for aspirin use rather than cause and effect. Whether regular aspirin use increases stroke risk for elderly people without cardiovascular disease can only be determined by randomized clinical trials.

Dorsal striatal size, shape, and metabolic rate in never-medicated and previously medicated schizophrenics performing a verbal learning task

BACKGROUND

Magnetic resonance imaging and positron emission tomography were used to study the size and metabolic rate of the caudate and the putamen in 18 patients with schizophrenia (n=16) or schizo-affective disorder (n=2) and 24 age- and sex-matched control subjects.

METHODS

The patients were either never medicated (n=7) or drug free (n=11) for a median of 3 weeks. During uptake of fludeoxyglucose F 18, all patients performed a serial verbal learning test. Positron emission tomographic and magnetic resonance imaging scans were coregistered, and the caudate and the putamen were traced on the magnetic resonance image.

RESULTS

The striatum had a significantly lower relative metabolic rate in schizophrenics than in controls. Never-medicated patients had lower metabolic rates in the right putamen (ventral part of the dorsal striatum) than previously medicated patients. The caudate was significantly smaller in never-medicated patients than in controls and largest in previously medicated patients. Patients with higher relative metabolic rates in the putamen scored higher on the Abnormal Involuntary Movements Scale.

CONCLUSIONS

The findings are consistent with reports of striatal enlargement in previously medicated patients and size increases after neuroleptic treatment. Never-medicated patients, in contrast, had ventral striatal structures that were smaller and less active than those observed in controls and previously medicated patients.

G-CSF mobilization of haemopoietic cell populations in SCID mice engrafted with human leukaemia

We have studied granulocyte colony-stimulating factor (G-CSF)-induced mobilization of haemopoietic cells in severe combined immune-deficient (SCID) mice engrafted with human leukaemia. Three leukaemia cell lines were investigated: the HL60 myeloblastic cell line, a chronic myeloid leukaemia (CML) xenograft cell line and an acute myeloid leukaemia (AML) xenograft line. Engraftment was detected using immunofluorescent staining of class I human leukocyte antigens and flow cytometry. All the tumours grew as disseminated disease with engraftment of bone marrow preceding involvement of peripheral blood (PB). After treatment with G-CSF (250 microg/kg/day) for 5 days, mobilization of haemopoietic progenitor cells (HPCs) was observed in non-engrafted SCID mice (40-fold) and in mice engrafted with human leukaemia (20-fold). G-CSF stimulated increases in PB HPCs and total numbers of host nucleated cells in leukaemia-bearing mice but did not induce rises in numbers of circulating HL60 colony-forming cells. Similarly, in mice engrafted with human CML or AML, G-CSF did not increase the number of malignant cells in the PB. These results provided evidence that the migration of normal and malignant haemopoietic cells into the PB are controlled by different mechanisms, and that contamination of PBSC harvests with leukaemic cells in SCID-human chimaeric mice is not enhanced by G-CSF-stimulated mobilization.

RNA splicing: out of the loop

Recent functional analysis of catalytic and exon-binding domains from group II autocatalytic introns has revealed haunting similarities with small nuclear RNA sequences in the spliceosome.

A comparison of the effect of the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors simvastatin, lovastatin and pravastatin on leukaemic and normal bone marrow progenitors

Simvastatin is an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase and also selectively inhibits the growth of leukaemic progenitor cells. The antileukaemic action of simvastatin was compared in vitro with that of lovastatin and pravastatin, chemically related compounds which are also competitive inhibitors of HMG-CoA reductase. After 18 hours incubation with 2.5-20 microM of inhibitor, no effect was observed by any of the compounds on the subsequent clonogenic growth of normal bone marrow (BM) progenitor cells from 4 donors and BM cells from one patient in remission. However, simvastatin and lovastatin produced inhibition of acute myeloid leukaemia (AML) progenitor cell growth of between 25% and 100% in 5 populations tested (4 primary AMLs and the HL60 cell line). Pravastatin showed similar growth inhibitory effects to simvastatin and lovastatin in 2 out of 3 primary AMLs but was less active against one primary AML cell population and HL60 cells. These results indicate that, in addition to simvastatin, lovastatin and pravastatin are also selective inhibitors of leukaemic cell growth, however simvastatin was chosen for clinical trial in patients with leukaemia.

Equivalent background speed in recovery from motion adaptation

We measured, in the same observers, (1) the detectability, d, of a small rotational jump following adaptation to rotational motion and (2) the detectability of the same jump when superimposed on one of several background rotation speeds. Following 90 s of motion adaptation the detectability of the jump was impaired, and sensitivity slowly recovered over the course of 60 s. The detectability of the jump was also impaired by the background speed in a way consistent with a quadratic form of Weber's law. We propose that motion adaptation impairs the detectability of the small jump because it is as if an equivalent background speed has been superimposed on the display. We measured the equivalent background by finding the real background speed that produced the same d' at each instant in the recovery from motion adaptation. The equivalent background started at approximately one to two thirds the speed of the adapting motion, declined rapidly, rose to a small peak at 30 s, then disappeared by 60 s. Since the equivalent background speed corresponds to the speed of the motion aftereffect, we have measured the time course of the motion aftereffect with objective psychophysics.

Utility of new electrocardiographic models for left ventricular mass in older adults. The Cardiovascular Health Study Collaborative Research Group

Several multivariate statistical models have recently been introduced for estimation of left ventricular mass from standard 12-lead electrocardiographic measurements. The validity of these algorithms has not been adequately evaluated. The objective of this investigation was to compare the associations between echocardiographic and electrocardiographic left ventricular mass values with clinical and subclinical indexes of coronary heart disease. The evaluation was performed with participants of the Cardiovascular Health Study, a population-based sample of 5201 men and women aged 65 years and older. Echocardiographic M-mode measurements of left ventricular mass were performed from videotape recordings with the use of a strictly standardized protocol. Electrocardiographic algorithms of the Novacode program and new algorithms derived from the Cardiovascular Health Study population were used for left ventricular mass prediction. Echocardiographic and electrocardiographic determinations of left ventricular mass were technically successful in 3410 (65.6%) and 5013 (96.4%) participants, respectively. The Novacode model overestimated echocardiographic left ventricular mass. Compared with the Novacode model, the new Cardiovascular Health Study electrocardiographic model, which includes adjustment for body weight, eliminated left ventricular mass prediction bias and improved the correlation between echocardiographic and electrocardiographic left ventricular mass from .33 to .54 in women and from .46 to .51 in men. Echocardiographic and electrocardiographic models both demonstrated similar and about equally strong associations with overt and subclinical disease and with risk factors for left ventricular hypertrophy. These observations demonstrate the potential utility of electrocardiographic models for left ventricular mass estimation.

Clinical improvement of photoaged skin with 50% glycolic acid. A double-blind vehicle-controlled study

BACKGROUND

Although there is increasing interest in the use of glycolic acid in the treatment of photoaged skin, to our knowledge, no controlled study has been done to assess the efficacy or the mode of this agent.

OBJECTIVE

The purpose of this study was to determine whether 50% glycolic acid can improve photoaged skin and to study the histological basis for this improvement.

METHODS

Forty-one volunteers were recruited into this double-blind vehicle-controlled study. Glycolic acid (50%) or vehicle was applied topically for 5 minutes to one side of the face, forearms, and hands, once weekly for 4 weeks. Punch biopsies were taken at pretherapy and at 5 weeks for histologic study.

RESULTS

Significant improvement noted included decrease in rough texture and fine wrinkling, fewer solar keratoses, and a slight lightening of solar lentigines. Histology showed thinning of the stratum corneum, granular layer enhancement, and epidermal thickening. Some specimens showed an increase in collagen thickness in the dermis.

CONCLUSION

The results of this study demonstrate that the application of 50% glycolic acid peels improves mild photoaging of the skin.

Anthracyclines

The genotoxicity and carcinogenicity data from in vitro and in vivo studies conducted during preclinical safety assessment of doxorubicin (DOXO), epirubicin (EPI) and idarubicin (IDA), are reviewed. The genotoxicity assays included a) gene mutation in Salmonella typhimurium with 5 tester strains; b) gene mutation in the V79 mammalian (lung) cell line; c) chromosome aberrations in human lymphocytes cultured in vitro; and d) chromosome aberrations in mouse bone marrow cells after intravenous (i.v.) administration in vivo. The long-term toxicity studies in the rat included a) single dose administration (3 mg/kg DOXO, 3.6 EPI and 0.75 IDA) to female rats of two different age groups, i.e. younger (7 weeks old at dosing) and older (13 weeks old), followed by one-year observation; and b) multiple dose administration to male and female rats (7 weeks old at dosing), consisting of i.v. administration of 0.25, 0.5 and 1 mg/kg DOXO or EPI and 0.06, 0.125 and 0.25 mg/kg IDA, once every 3 weeks for 10 cycles, followed by 18 months of observation. The genotoxicity studies revealed activity in gene mutation assays in bacterial and mammalian cells, and in chromosome aberration assays in human lymphocytes in vitro and in mouse bone marrow in vivo. In the two long-term studies in the rat, only mammary tumors were present. This finding was expected and, according to the literature, can be considered as species specific and not directly compound-related. The lack of tumor induction at the usual target organs for DNA reactive compounds, which are almost the same as those considered as target organs in anthracycline-exposed animals, indicates that the type and the extent of DNA damage precludes stimulation for proliferation and induction of neoplasia. Although an epigenetic mechanism can be hypothesized, support for such a mechanism is lacking.