Neointimal thickening after stent delivery of paclitaxel: change in composition and arrest of growth over six months

OBJECTIVES

The purpose of this study was to determine long-term effects of stent-based paclitaxel delivery on amount, rate and composition of neointimal thickening after stent implantation.

BACKGROUND

Paclitaxel prevents vascular smooth muscle cell proliferation and migration in vitro and in vivo. These actions, coupled with low solubility, make it a viable candidate for modulating vascular responses to injury and prolonged effects after local delivery. We asked whether local delivery of paclitaxel for a period of weeks from a stent coated with a bioerodible polymer could produce a sustained reduction in neointimal hyperplasia for up to six months after stenting.

METHODS

Stainless steel stents were implanted in the iliac arteries of rabbits after endothelial denudation. Stents were uncoated or coated with a thin layer of poly(lactide-co-sigma-caprolactone) copolymer alone or containing paclitaxel, 200 microg.

RESULTS

Paclitaxel release in vitro followed first-order kinetics for two months. Tissue responses were examined 7, 28, 56 or 180 days after implantation. Paclitaxel reduced intimal and medial cell proliferation three-fold seven days after stenting and virtually eliminated later intimal thickening. Six months after stenting, long after drug release and polymer degradation were likely complete, neointimal area was two-fold lower in paclitaxel-releasing stents. Tissue responses in paclitaxel-treated vessels included incomplete healing, few smooth muscle cells, late persistence of macrophages and dense fibrin with little collagen.

CONCLUSIONS

Poly(lactide-co-sigma-caprolactone) copolymer-coated stents permit sustained paclitaxel delivery in a manner that virtually abolishes neointimal hyperplasia for months after stent implantation, long after likely completion of drug delivery and polymer degradation.

Qualitative block design analysis in posttraumatic stress disorder

Qualitative and quantitative Block Design performance was examined in Vietnam combat veterans with PTSD diagnoses (n = 23) and Vietnam combat veterans without PTSD or other mental disorders diagnoses (n = 19). Results indicated that PTSD-diagnosed veterans committed more single block rotations than the comparison sample, and that their errors occurred more frequently in right hemispace than errors made by the comparison sample. The two groups did not differ in the number of configural errors made, errors committed in left hemispace, or in quantitative performance measures. Findings are suggestive of relative left hemisphere hypoactivation and are congruent with prior research documenting cerebral asymmetries in emotional disorders.

The comparative pathobiology of atherosclerosis and restenosis

Percutaneous coronary interventions (PCIs) play an increasingly important role in the management of patients with coronary artery disease. However, these important procedures are complicated by restenosis in a sizeable number of patients. The pathobiology of atherosclerosis comprises a complex interaction among lipids, the endothelium, circulating and tissue inflammatory cells, platelets, and vascular smooth muscle cells. The superimposition of the mechanical and cellular consequences of PCIs on the abnormal substrate of atherosclerosis leads to a characteristic and distinct pathobiology that initiates and perpetuates restenosis. A clear understanding of the significant differences between atherosclerosis and restenosis will provide a rational basis for developing treatment plans that always address both problems. This article reviews and contrasts the pathobiology of atherosclerosis and restenosis and compares the mechanisms and time-course of these distinct entities.

Randomized trial of a specialist genetic assessment service for familial breast cancer

BACKGROUND

Because of the growing demand for genetic assessment, there is an urgent need for information about what services are appropriate for women with a family history of breast cancer. Our purpose was to compare the psychologic impact and costs of a multidisciplinary genetic and surgical assessment service with those of current service provisions.

METHODS

We carried out a prospective randomized trial of surgical consultation with (the trial group) and without (the control group) genetic assessment in 1000 women with a family history of breast cancer. All P: values are from two-sided tests.

RESULTS

Although statistically significantly greater improvement in knowledge about breast cancer was found in the trial group (P: =.05), differences between groups in other psychologic outcomes were not statistically significant. Women in both groups experienced statistically significant reductions in anxiety and found attending the clinics to be highly satisfying. An initial specialist genetic assessment cost pound 14.27 (U.S. $22.55) more than a consultation with a breast surgeon. Counseling and genetic testing of affected relatives, plus subsequent testing of family members of affected relatives identified as mutation carriers, raised the total extra direct and indirect costs per woman in the trial group to pound 60.98 (U.S. $96.35) over costs for the control subjects.

CONCLUSIONS

There may be little benefit in providing specialist genetics services to all women with a family history of breast cancer. Further investigation of factors that may mediate the impact of genetic assessment is in progress and may reveal subgroups of women who would benefit from specialist genetics services.

E2F4 is essential for normal erythrocyte maturation and neonatal viability

The retinoblastoma protein (pRB) plays a key role in the control of normal development and proliferation through the regulation of the E2F transcription factors. We generated a mutant mouse model to assess the in vivo role of the predominant E2F family member, E2F4. Remarkably, loss of E2F4 had no detectable effect on either cell cycle arrest or proliferation. However, E2F4 was essential for normal development. E2f4-/- mice died of an increased susceptibility to opportunistic infections that appeared to result from craniofacial defects. They also displayed a variety of erythroid abnormalities that arose from a cell autonomous defect in late stage maturation. This suggests that E2F4 makes a major contribution to the control of erythrocyte development by the pRB tumor suppressor.

Assessment of different antibacterial effect measures used in in vitro models of infection and subsequent use in pharmacodynamic correlations for moxifloxacin

A dilutional culture in vitro pharmacodynamic model of infection was used to assess the best measure of antibacterial effect for moxifloxacin at simulated human doses of 400 mg 24 hourly for 48 h. This was then related to two pharmacodynamic parameters, the drug area under curve: MIC ratio (AUC/MIC) and the length of time that the drug concentration remained above the MIC of the bacterium (T > MIC). Twenty-one bacterial strains (Streptococcus pneumoniae n = 6; Haemophilus influenzae n = 6; Moraxella catarrhalis n = 3; beta-haemolytic streptococci n = 3; Staphylococcus aureus n = 3; MIC range 0.06-3.6 mg/L) were tested in 69 individual simulations. The measures or parameters of antibacterial effect considered were log change in viable count in the initial inoculum at 12 h (triangle up12), 24 h (triangle up24), 36 h (triangle up36), 48 h (triangle up48), maximum reduction in count (triangle up(max)); time for bacterial counts to reduce by 100-fold from the initial density (T99) or 1,000-fold (T99.9); and area under the bacterial kill curve from 0 to 24 h (AUBKC(24)) or from 0 to 48 h (AUBKC(48)). triangle up12, triangle up24, triangle up36, triangle up48, triangle up(max), T99, T99.9 did not vary over the complete range of MICs; at high MICs, especially with Gram-positive bacteria the T99 and T99.9 values were >48 h while at low MICs, especially with Gram-negative bacteria, bacterial counts were reduced below the limit of detection with triangle up12, triangle up24, triangle up36, triangle up48 and triangle up(max) exceeding >6.5 log reduction. AUBKC(24) and AUBKC(48) varied more completely over the range of MICs and more importantly had the best within-strain reproducibility (median percentage coefficient of variation <15%). The relationship between the transformed AUBKC(24) and AUC/MIC could be described by a sigmoid Emax model but the relationship with T > MIC could not. Use of weighted least squares regression to examine the combined effect of AUC/MIC and T > MIC on AUBKC(24) indicated that AUC/MIC provided a good fit to the data (r(2) = 0.94) and adding T > MIC did not improve the model fit. Cox proportional hazards regression indicated that AUC/MIC was predictive of T99 and in a multivariate model although AUC/MIC predicted outcome after fitting AUC/MIC, T > MIC was not significant. AUBKC was thus shown to be the optimum measure of antibacterial effect to use in pharmacodynamic studies of moxifloxacin and AUC/MIC the best predictor of antibacterial effect as measured by AUBKC(24) or T99. These results are in good agreement with animal data on moxifloxacin pharmacodynamics and human data for some other fluoroquinolones.

Dynamic thermomechanical properties and crystallinity of ultrahigh molecular weight polyethylene tibial inserts

A dynamic thermomechanical analysis method was used to determine the values of the viscoelastic parameters, storage modulus (E') and the tangent of the loss angle (tan delta) of samples taken from the near surface and core regions of ultrahigh molecular weight polyethylene (UHMWPE) bar stock specimens that had been aged in ambient laboratory air for 12 months (the control group) and UHMWPE tibial inserts that had been subjected to the following treatments: gamma sterilization followed by shelf aging in ambient laboratory air for between 56 and 112 months or ethylene oxide (EtO) gas sterilization followed by shelf aging in ambient laboratory air for 73 months. Differential scanning calorimetry was used to determine the melt temperature and percentage crystallinity (%C) of these samples. There were three main findings. First, EtO sterilization produced no statistically significant effect on the values of E' or tan delta (relative to those for the control group), but the values of these parameters were markedly affected by gamma sterilization. Second, for gamma-irradiated samples, E' increased with an increase in the shelf aging time. Third, there was a strong direct association between E' and % C. The various potential uses of this association are described, paying special attention to its likely role in predicting the in vivo wear of UHMWPE tibial inserts.

A randomized trial of hierarchical counseling in a short, clinic-based intervention to reduce the risk of sexually transmitted diseases in women

INTRODUCTION

Effective public health interventions to reduce the incidence of sexually transmitted disease (STD), including HIV, among women are urgently needed.

METHODS

A randomized trial among STD clinic patients of two types of counseling regarding methods to reduce disease transmission: a 'hierarchical' message (HP), with counseling on male condoms, female condoms, diaphragms, cervical caps, and spermicides (three formulations) and a single method message (SM) covering male condoms only or female condoms only. For this analysis, 1591 subjects received one of three educational messages at the central public STD clinic in Philadelphia. Disease incidence data for up to 6 months following the index visit were extracted from the clinic's electronic database. The primary outcome was STD reinfection: laboratory-confirmed trichomonas infection and/or clinical diagnoses of at least one of four STD. Rates were based on the full sample of randomized women (full sample) and on the subset who spontaneously returned between 22 days and 183 days following their initial visit (returners).

RESULTS

Rates of trichomonas infection (SM 2.5% full sample and 12.9% returners versus HP 2.4% full sample and 11.5% returners) and clinical diagnoses (SM 6.3% full sample and 39.7% returners versus HP 6.9% full sample and 41.2% returners) did not differ across the two arms of the randomized trial, both as a straight percentage and in survival analysis (P = .81).

CONCLUSION

At least in this single-session intervention trial, increasing choices in protection for women did not produce a change in disease risk compared with single-method approaches.

Transparency effects on powder speckle decorrelation

Laser speckle decorrelation has previously been applied to measure the mean powder size of bulk powder beds and the roughness of porous rocks. The angular decorrelation rate of laser speckle from bulk powder beds correlates strongly with the mean powder size. However it was found that the angular decorrelation rates of transparent powders were much higher than those of opaque or dyed powders of the same size distribution. The accuracy of size measurements could be severely compromised if transparency effects were not compensated. Monte Carlo modelling of remitted photon path lengths in a powder bed suggests and experimental data supports that diffuse reflectance data may be used to correct for transparency effects on angular decorrelation rate data.

Randomised controlled trial of nurse practitioner versus general practitioner care for patients requesting "same day" consultations in primary care

OBJECTIVE

To ascertain any differences between care from nurse practitioners and that from general practitioners for patients seeking "same day" consultations in primary care.

DESIGN

Randomised controlled trial with patients allocated by one of two randomisation schemes (by day or within day).

SETTING

10 general practices in south Wales and south west England.

SUBJECTS

1368 patients requesting same day consultations.

MAIN OUTCOME MEASURES

Patient satisfaction, resolution of symptoms and concerns, care provided (prescriptions, investigations, referrals, recall, and length of consultation), information provided to patients, and patients' intentions for seeking care in the future.

RESULTS

Generally patients consulting nurse practitioners were significantly more satisfied with their care, although for adults this difference was not observed in all practices. For children, the mean difference between general and nurse practitioner in percentage satisfaction score was -4.8 (95% confidence interval -6.8 to -2.8), and for adults the differences ranged from -8.8 (-13.6 to -3.9) to 3.8 (-3.3 to 10.8) across the practices. Resolution of symptoms and concerns did not differ between the two groups (odds ratio 1.2 (95% confidence interval 0.8 to 1.8) for symptoms and 1.03 (0.8 to 1.4) for concerns). The number of prescriptions issued, investigations ordered, referrals to secondary care, and reattendances were similar between the two groups. However, patients managed by nurse practitioners reported receiving significantly more information about their illnesses and, in all but one practice, their consultations were significantly longer.

CONCLUSION

This study supports the wider acceptance of the role of nurse practitioners in providing care to patients requesting same day consultations.

E2f3 is critical for normal cellular proliferation

E2F is a family of transcription factors that regulate both cellular proliferation and differentiation. To establish the role of E2F3 in vivo, we generated an E2f3 mutant mouse strain. E2F3-deficient mice arise at one-quarter of the expected frequency, demonstrating that E2F3 is important for normal development. To determine the molecular consequences of E2F3 deficiency, we analyzed the properties of embryonic fibroblasts derived from E2f3 mutant mice. Mutation of E2f3 dramatically impairs the mitogen-induced, transcriptional activation of numerous E2F-responsive genes. We have been able to identify a number of genes, including B-myb, cyclin A, cdc2, cdc6, and DHFR, whose expression is dependent on the presence of E2F3 but not E2F1. We further show that a critical threshold level of one or more of the E2F3-regulated genes determines the timing of the G(1)/S transition, the rate of DNA synthesis, and thereby the rate of cellular proliferation. Finally, we show that E2F3 is not required for cellular immortalization but is rate limiting for the proliferation of the resulting tumor cell lines. We conclude that E2F3 is critical for the transcriptional activation of genes that control the rate of proliferation of both primary and tumor cells.

Why do women attend familial breast cancer clinics?

The increasing demand for genetic assessment for familial breast cancer has necessitated the development of cancer genetics services. However, little is known about the factors motivating the client population likely to approach these services. A cross sectional questionnaire survey of 1000 women with a family history of breast cancer was conducted to identify self-reported reasons for attending a familial breast cancer clinic and possible differences in the characteristics of women who were attending for diverse reasons. Before attendance at clinic, 833 women completed a baseline questionnaire (83% response rate). Women who gave personal risk (n=188), awareness of a family history (n=120), risk to family members (n=84), reassurance (n=69), genetic testing (n=65), breast screening (n=46), or prevention (n=39) as their main reason for attending were compared on demographic and medical variables, and on psychological variables including general anxiety, cancer worry, perceived risk, and attitudes towards prophylactic surgery and genetic testing. Important differences in the psychological characteristics of these groups were found, which were unrelated to reported family history. In particular, women who primarily wanted genetic testing felt extremely vulnerable to developing breast cancer, were more likely to be considering prophylactic surgery, and perceived fewer limitations of testing. Those who primarily wanted reassurance were highly anxious about the disease. We recommend that cancer genetics services take into consideration the informational and psychological needs and concerns of their client group.

A model protocol evaluating the introduction of genetic assessment for women with a family history of breast cancer

Randomised controlled trials allow comparisons to be made between different models of service delivery, but have not been used in the field of clinical genetics. With the advent of clinical governance, the evidence provided by such trials will be increasingly important in informing and shaping clinical genetics practice. The TRACE project (Trial of genetic assessment in breast cancer) is a randomised controlled trial of genetic assessment for women who are at increased risk of breast cancer because of their family history. The absence of cancer genetics service provision in Wales before this study gave a window of opportunity in which this important trial could be conducted. The present paper describes how TRACE will provide crucial evidence regarding the psychosocial as well as resource implications of adding individualised genetic assessment, genetic counselling, and (where appropriate) gene testing to typical advice and surveillance from a hospital breast clinic. In addition, it is anticipated that TRACE will represent a model for future trials of service delivery in the increasing number of complex genetic disorders where evidence on the economic implications of screening and management is currently limited.

Relative activity and referral patterns for diabetes and non-diabetes in general practice

AIMS

To describe and compare general practice (GP) activity for patients with and without diabetes using a survey of general practices representing over 10% of the Welsh population.

METHODS

The Welsh GP Morbidity Database Project (GPMDP) collected data including demographic and lifestyle information and consultation data such as diagnosis, referral and surgical procedures. These data were analysed to establish the annual period prevalence of diabetes and compare the relative number of consultations and referrals.

RESULTS

A total of 4,182 diabetic patients were recorded (prevalence 1.41%) and accounted for 77,371 (4.4%) consultations. Patients with diabetes were four-times more likely to be referred to community services (relative risk (RR) 4.1, 95% CI 3.7-4.7), in particular district nursing (RR 3.8, 1.9-7.7), optician services (RR 8.9, 5.0-15.7), chiropody (RR 8.2 6.4-10.5) and dietician services (RR 21.2, 17.6-25.5). Patients with diabetes were also more likely to be followed-up in general practice (RR 6.7, 6.2-7.2) both within 1 month (RR 6.7, 6.2-7.2) and 1 month to 1 year (RR 9.7, 8.9-10.7). Emergency admissions were also more likely for patients with diabetes (RR 6.8, 6.2-7.5) as were elective admissions to general medicine (RR 5.6, 4.6-6.7), surgery (RR 1.8, 1.5-2.0) and opthalmology (4.2, 3.4-5.2).

CONCLUSION

The increased utilization of health services apparent in secondary care was confirmed in primary care. Further research is required to determine levels of community activity after initial referral.

Stent and artery geometry determine intimal thickening independent of arterial injury

BACKGROUND

Clinical trials show that larger immediate postdeployment stent diameters provide greater ultimate luminal size, whereas animal data show that arterial injury and stent design determine late neointimal thickening. At deployment, a stent stretches a vessel, imposing a cross-sectional polygonal luminal shape that depends on the stent design, with each strut serving as a vertex. We asked whether this design-dependent postdeployment luminal geometry affects late neointimal thickening independently of the extent of strut-induced injury.

METHODS AND RESULTS

Stainless steel stents of 3 different configurations were implanted in rabbit iliac arteries for 3 or 28 days. Stents designed with 12 struts per cross section had 50% to 60% less mural thrombus and 2-fold less neointimal area than identical stents with only 8 struts per cross section. Sequential histological sectioning of individual stents showed that immediate postdeployment luminal geometry and subsequent neointimal area varied along the course of each stent subunit. Mathematical modeling of the shape imposed by the stent on the artery predicted late neointimal area, based on the re-creation of a circular vessel lumen within the confines of the initial stent-imposed polygonal luminal shape.

CONCLUSIONS

Immediate postdeployment luminal geometry, dictated by stent design, determines neointimal thickness independently of arterial injury and may be useful for predicting patterns of intimal growth for novel stent designs.

Decreased neointimal formation in Mac-1(-/-) mice reveals a role for inflammation in vascular repair after angioplasty

Inflammation plays an essential role in the initiation and progression of atherosclerosis, but its role in vascular repair after mechanical arterial injury (i.e., percutaneous transluminal coronary angioplasty, PTCA) is unknown. In animal models of vascular injury, leukocytes are recruited as a precursor to intimal thickening. Furthermore, markers of leukocyte activation - in particular, increased expression of the beta2-integrin Mac-1 (alphaMbeta2, or CD11b/CD18), which is responsible for firm leukocyte adhesion to platelets and fibrinogen on denuded vessels - predict restenosis after PTCA. To determine whether Mac-1-mediated leukocyte recruitment is causally related to neointimal formation, we subjected mice lacking Mac-1 to a novel form of mechanical carotid artery dilation and complete endothelial denudation. We now report that the selective absence of Mac-1 impairs transplatelet leukocyte migration into the vessel wall, reducing leukocyte accumulation over time. Diminished medial leukocyte accumulation was accompanied by markedly reduced neointimal thickening after vascular injury. These data establish a role for inflammation in neointimal thickening and suggest that leukocyte recruitment to mechanically injured arteries may prevent restenosis.

Factors predicting cesarean delivery for American Indian women in New Mexico

BACKGROUND

American Indian women have one of the lowest cesarean delivery rates among all ethnic groups evaluated in the United States. Our objective was to identify risk factors for cesarean delivery among American Indian women in New Mexico.

METHODS

Live birth certificate data (1994) from the New Mexico Bureau of Vital Records and Health statistics were used to compare American Indian women who had a cesarean delivery with those who had a vaginal delivery. We examined demographic, prenatal, and intrapartum factors to determine risk factors for cesarean delivery.

RESULTS

In 1994 American Indian women in New Mexico had a cesarean delivery rate of 12 percent. Risk factors for cesarean delivery included age equal to or over 35 years (OR = 1.8, 1.3-2.5) and nulliparity (OR = 1.9, 1.5-2.5). Obstetric risk factors included prematurity (OR = 2.3, 1.5-3.6), low birthweight (OR = 2.6, 1.7-4.2), diabetes (OR = 1.7, 1.1-2.5), pregnancy-induced hypertension (OR = 2.6, 1.8-3.8), and labor and delivery complications (OR = 9.5, 7.5-12.1). Age less than 20 years was negatively associated with cesarean delivery (OR = 0.5, 0.3-0.7).

CONCLUSION

American Indian women have risk factors for cesarean delivery that are similar to those reported in other populations. Future prospective research evaluating intrapartum management may help identify reasons for the low cesarean birth rate.

Randomized clinical trial of early laparoscopy in the management of acute non-specific abdominal pain

BACKGROUND

Abdominal pain of uncertain aetiology (non-specific abdominal pain; NSAP) is the commonest reason for emergency surgical admission. The aim of this study was to examine the role of early laparoscopy in the management of NSAP.

METHODS

Some 120 patients, admitted between November 1995 and October 1998 with acute abdominal pain of uncertain aetiology, were randomized into two groups: group 1 had laparoscopy during the first 18 h of admission and group 2 had close observation, conventional investigation and surgical intervention if signs of peritonism developed. Outcome measures were diagnosis, operative procedures, duration of hospital stay, readmission rate, morbidity and death, patient satisfaction and total number of investigations performed.

RESULTS

Median hospital stay was 2 (range 1-13) days in both groups (P = 0.87). A diagnosis was established in 48 (81 per cent) of 59 patients in group 1 compared with 22 (36 per cent) of 61 in group 2 (P < 0.0001). The morbidity rate was 14 (24 per cent) of 59 in group 1 and 19 (31 per cent) of 61 in group 2 (P = 0.3629). The readmission rate at a median follow-up of 21 (range 1-35) months was 17 (29 per cent) of 59 in group 1 compared with 20 (33 per cent) of 61 in group 2 (P = 0. 6375). Well-being scores improved from 134 on admission to 149 of 177 6 weeks later in group 1 (P = 0.007) and from 132 to 143 of 177 in group 2 (P = 0.089).

CONCLUSION

Early laparoscopy provided a higher diagnostic accuracy and improved quality of life in patients with NSAP.

Distribution of D1S80 alleles in the Bahrainian population

This study demonstrates that the locus D1S80 is highly polymorphic in the Bahrainian population. There were 24 different D1S80 alleles and 51 distinct genotypes observed in 198 Bahrainians. There was one allele observed that was smaller than the 14 repeat allele. This data set meets the Hardy-Weinberg expectations (HWE) and could be a useful marker for parentage testing and forensic applications.

Measuring arterial strain induced by endovascular stents

Endovascular stents are expandable, fenestrated tubes that are threaded in their collapsed state through an artery to a site of occlusion, plastically enlarged and left as permanent implants to scaffold the artery open. The stent induces large-scale vascular strains that are difficult to measure in vivo and yet can be critical determinants of stent-vessel biology. A method is developed to measure the strain tensor developed on the surface of an artery as a stent is expanded in vivo. Arterial sections are marked with reference points and imaged as the stent is expanded. An axially symmetric parametric model of the artery is determined for each expansion time-point, and these reference points are back-projected onto this surface. The back-projected reference points are grouped and analysed to determine the circumferential, axial and torsional strain tensor components in each arterial subsection. The method is characterised in vitro using bovine artery segments and a latex phantom, and is then tested on rabbits to demonstrate its feasibility in vivo. In vitro experiments on stented bovine arteries show typical post-stenting strains of 0.60, -0.26, and 0.08 mm mm-1 in the circumferential, axial and torsional directions, respectively, sampled every 1 mm along the length of the stented region. Phantom experiments characterise the RMS error of system measurements as 0.1 mm mm-1. The system is shown capable of measuring strains of straight, accessible vessels in the presence of respiratory/cardiac motion and visual glare in vivo.

Typing of eight short tandem repeat (STR) loci in a Saudi Arabian population

Allele frequency data for eight short tandem repeat (STR) loci, HUMF13A01, HUMFESFPS, HUMF13B, HUMLPL, HUMCSF1PO, HUMTPOX, HUMTHO1 and HUMvWA, were obtained for unrelated individuals in a Saudi Arabian population. All loci, except F13B (P = 0.037) and LPL (P = 0.035), meet Hardy-Weinberg expectations, based on the exact test. The most informative locus is HUMvWA (PD = 0.936) and the least discriminating is the HUMTPOX locus (PD = 0.820). There was only one observation of a departure from expectation from pairwise locus comparisons. These data can be used for estimating the frequency of STR profiles in a Saudi Arabian population.