Relationship between oversizing of self-expanding stents and late loss index in carotid stenting

Stenting of the internal carotid artery is facilitated by stenting across the carotid bifurcation and sizing the diameter of a self-expanding stent to the large common carotid segment. This usually results in marked oversizing of the self-expanding stent in the internal carotid segment. This study was done to determine the relationship between stent oversizing and late luminal loss index after stenting of the internal carotid artery. Between September 1995 and March 1997, there were 165 patients (189 vessels) who underwent successful carotid stenting with self-expanding stents. Fifty-nine patients (63 vessels) had six-month follow-up carotid angiograms and on-line quantitative angiographic analysis. The mean reference diameter of the internal carotid arteries was 4.93+/-1.31 mm. Nominal stent size was 5 mm in 4 patients, 6 mm in 6 patients, 8 mm in 106 patients, 10 mm in 77 patients, and 12 mm in 1 patient. The average stent/patient was 1.03+/-0.16. There were three patients who had more than 50% diameter renarrowing at follow-up. The mean late loss index was 0.25+/-0.41. By linear regression analysis, there was no clear linear relationship between stent oversizing and late loss index after stenting (correlation coefficient = -0.21, P = 0.09). When analysis of variance with linear contrast was used to analyze six groups of different stent/artery ratios (from 1.4 to > or = 2), late loss indexes are significantly lower in the groups of high stent/artery ratio than the groups of low stent/artery ratio (P = 0.01). The process of oversizing of self-expanding stents deployed in the internal carotid artery does not appear to be associated with late restenosis and high stent/artery ratio seems to be associated with low late loss index.

Efficacy of coronary stenting in the management of cardiac allograft vasculopathy

We undertook a study to determine the efficacy of stents in reducing restenosis in cardiac allograft vasculopathy. The result shows that coronary stenting significantly reduces restenosis in cardiac allograft vasculopathy compared with balloon angioplasty alone.

Herpes simplex myelitis in a patient with acquired immune deficiency syndrome

Herpes simplex virus type-I is the commonest cause of focal encephalitis in immunocompetent adults. We report a 35 year old man, who presented with acute ascending myelitis which progressed to encephalitis within one week. The patient's MRI revealed nonhaemorrhagic lesions in frontotemporal areas and midbrain without any evidence of herniation. The CSF was positive for IgM and IgG antibodies against herpes simplex virus 1 (HSV1) and serum was positive for HIV by ELISA and Western blot techniques. The patient died on 18th day of illness due to resistant pseudomonas septicaemia.The presence of disseminated involvement of the central nervous system in HSV infection should raise the suspicion of the HIV coinfection.

Estimation of fasting and post oral glucose serum insulin levels in hypertensive and obese subjects

Insulin resistance and consequent hyperinsulinemia has been documented as a frequent occurrence in hypertension and obesity. Fasting and post oral glucose serum insulin levels serve as reliable markers of the state of insulin resistance. In this study, fasting serum insulin levels, as measured by radio-immunoassay method, were found to be more increased in obese individuals than in those with hypertension alone. While, post-oral glucose load serum insulin levels increased more in hypertensive individuals than those with obesity alone. In subjects who had obesity and hypertension together, the fasting serum insulin levels did not show much change while post oral glucose load serum insulin levels greatly increased suggesting a compounding effect.

Elective carotid artery stenting in the presence of contralateral occlusion

Significant carotid stenosis in the presence of an occluded contralateral artery has a poor prognosis with medical therapy alone. Carotid cross clamping during surgical endarterectomy results in critical flow reductions in patients with inadequate collateral flow, and represents a significant risk for procedural strokes. Carotid stenting is being evaluated as an alternative to endarterectomy. We describe the immediate and late outcome of a series of 26 patients treated with carotid stenting in the presence of contralateral carotid occlusion. The mean age of the patients in this group was 65 +/- 9 years, 23 (89%) were men and 10 (39%) were symptomatic from the vessel treated. The procedural success of carotid stenting in this group of patients was 96%. The mean diameter stenosis was reduced from 76 +/- 15% to 2.8 +/- 5%. There was 1 (3.8%) minor stroke in a patient who developed air embolism during baseline angiography. At late follow-up there was no neurologic event in any patient at a mean of 16 +/- 9.5 months after the procedure. Thus, carotid stenting of lesions with contralateral occlusion can be performed successfully with a low incidence of procedural neurologic complications and late stroke.

Angioplasty of totally occluded old vein grafts with new interventional techniques: a long-term follow-up study

The long-term patency of saphenous vein graft (SVG) lesions after intervention has been shown to be improved with new interventional techniques such as stents. Long-term outcome of patients undergoing successful angioplasty of totally occluded old SVGs with new devices is unknown. From July 1994 to June 1996, 19 patients with totally occluded old SVGs had successful angioplasty with new interventional techniques. Mean SVG age was 123 +/- 8 mo. Thrombolysis in myocardial infarction trial (TIMI) flow was 0 in all target lesions. TIMI 2 or 3 flow was restored after angioplasty in all patients. Intracoronary urokinase, transluminal extractional atherectomy, and stenting were used in 14, 12, and 6 patients, respectively. There was one in-hospital death due to ongoing myocardial infarction, no recurrent infarction, and no repeat angioplasty or bypass surgery in the hospital. At follow-up of 21 +/- 1 mo, there was one sudden death and one myocardial infarction. Five patients had repeat coronary bypass surgery, and 4 had repeat angioplasty. Thirteen patients remained asymptomatic, and 4 had angina. The long-term outcome of patients who had successful reopening of occluded old SVGs is encouraging in this small sample.

Production of cytotoxic factor by peripheral blood mononuclear cells (PBMC) in patients with dengue haemorrhagic fever

A unique cytokine, human cytotoxic factor (hCF), has been shown to occur in the sera of patients with dengue fever (DF) and dengue haemorrhagic fever (DHF). The present study was undertaken to investigate the ability of fresh PBMC of such patients to produce hCF. The PBMC were cultured for 24 h and the culture supernatants (CS) were analysed for the presence of hCF by cytotoxicity assay, competitive ELISA and dot blot tests. In 90% of 246 cases CS were positive for hCF by the three tests. CS were positive for hCF in PBMC collected from days 1-20 of illness but not at later periods. Higher cytotoxic activity was observed in CS of days 1-4 of illness and was highest in cases of DHF grade IV and lowest in cases of DF. Dot blot hybridization of RNA extracted from the PBMC of the patients showed the presence of mRNA for hCF in 94% of cases. A similar number of patients showed the presence of hCF in situ in the PBMC smears by fluorescent antibody technique. hCF was found only in CD4+ T cells. The findings thus present direct evidence of the production of hCF by CD4 T cells of cases of DF/DHF.

Predictors of stroke complicating carotid artery stenting

BACKGROUND

The evolving technique of carotid stenting is being evaluated as an alternative to endarterectomy. Identification of the factors that predispose a patient to neurological complications would facilitate further refinement of the technique and optimize patient selection.

METHODS AND RESULTS

We analyzed the impact of various clinical, morphological, and procedural determinants on the development of procedural strokes in 231 patients who underwent elective (primary) stenting of 271 extracranial carotid arteries. The mean age of the patients was 68.7+/-10 years, 165 (71%) were males, and 139 (60%) had symptoms attributed to the lesion treated. This series represented a high-risk subset with 164 patients (71%) having significant coronary artery disease, 91 (39%) having bilateral disease, and 28 (12%) having contralateral carotid occlusion. Of the treated vessels, 59 (22%) had prior carotid endarterectomy, 66 (24%) had ulcerated plaques, and 87 (32%) had calcified lesions. Only 37 treated vessels (14%) would have been eligible for inclusion in the North American Symptomatic Carotid Endarterectomy Trial (NASCET). There were 17 (6.2%) minor and 2 (0.7%) major strokes during and within 30 days of the procedure. NASCET-eligible patients had a low (2.7%) risk of procedural strokes after carotid stenting. The results of multivariate analysis revealed advanced age (P=.006) and presence of long or multiple stenoses (P=.006) as independent predictors of procedural strokes.

CONCLUSIONS

During this procedural developmental phase of carotid stenting, neurological complications were highly dependent on patient selection. Advanced age and long or multiple stenoses were independent predictors of procedural stroke.

A comparative study of trabecular bone properties in the spine and femur using high resolution MRI and CT

The purpose of this study was to use high resolution (HR) magnetic resonance (MR) and computed tomography (CT) images combined with texture analysis to investigate the trabecular structure of human vertebral and femoral specimens and to compare these techniques with bone mineral density (BMD) in the prediction of bone strength. Twenty-nine bone cubes were harvested from 12 proximal femur cadaver specimens and 29 from 8 spines. HR MR and CT images were obtained, and texture analysis techniques were used to assess trabecular structure. Additionally, BMD, elastic modulus (EM), and maximum compressive strength were determined. R2 for EM versus texture measures computed in the MR images was higher (R2 = 0.27-0.64, p < 0.01) in the spine than in the femur specimens (R2 = 0.12-0.22, p < 0.05). R2 values were similar in the CT images. R2 for EM versus BMD was 0.66 (p < 0.01) in the spine and 0.61 (p < 0.01) in the femur specimens. In the MR images, texture measures combined with BMD in a multivariate-regression model significantly increased R2, while improvement was less significant in the CT images. Thus, texture analysis may provide additional information needed to analyze bone strength and quality.

Osteogenic sarcoma: noninvasive in vivo assessment of tumor necrosis with diffusion-weighted MR imaging

PURPOSE

To evaluate diffusion-weighted magnetic resonance (MR) imaging for detecting tumor necrosis in an animal model of osteogenic sarcoma.

MATERIALS AND METHODS

Twelve rats with osteogenic sarcoma underwent T1-weighted unenhanced and gadolinium-enhanced spin-echo and diffusion-weighted spin-echo MR imaging. Histologic correlation was performed. Signal intensities, T2 relaxation times, normalized apparent diffusion coefficients, and relative signal intensity increases were calculated.

RESULTS

On diffusion-weighted images, necrotic tumor showed low signal intensity (mean normalized apparent diffusion coefficient, 0.46 +/- 0.20 [1 standard deviation]), indicating rapid diffusion of water molecules as a result of loss of membrane integrity, while viable tumor showed high signal intensity (mean normalized apparent diffusion coefficient, 0.16 +/- 0.05; P < .0001). Differences in the T2 relaxation times and relative signal intensity increases between viable and necrotic tumor were not statistically significant.

CONCLUSION

Normalized apparent diffusion coefficients are more accurate in differentiating between viable and necrotic tumor than are T2 relaxation times or relative signal intensity increases on contrast-enhanced images. Signal intensity overlap between viable and necrotic tumor on gadolinium-enhanced images may be caused by the small molecular size of the agent, which permeates the interstitial space freely, thereby also enhancing necrosis. Diffusion-weighted MR imaging depicts differences in diffusion and, ultimately, in membrane integrity between viable and necrotic tumor and may be used to monitor tumor viability during treatment.

Aortic valve replacement with biological substitute

In the quest for an ideal aortic valve substitute, homografts and autografts are well-established options. We reviewed our results with homografts and autografts for aortic valve replacement during the last 5 years. From March 1992 through July 1997, 189 patients (138 male and 51 female), age 8 months to 68 years (mean 31.0+/-4.2 years), underwent aortic valve replacement with a human biological substitute. Of these, 93 patients received a cryopreserved or antibiotic-preserved aortic/pulmonary homograft, whereas 96 patients underwent a Ross procedure. Etiology was rheumatic in 143 (75.6%) patients, bicuspid aortic valve in 40 (21.2%), Marfan's disease in 5 (2.6%), and myxomatous aortitis in 1 (0.5%). Among the homograft group, a scalloped subcoronary implantation technique was used in 54 patients, whereas 32 patients underwent root replacement. Five patients required aortic root and ascending aortia replacement for annuloaortic ectasia. In all patients undergoing the Ross procedure, a root replacement technique was used. Operative mortality was 7.4% (14 patients). Late mortality was 5.3% (10 patients). Follow-up ranged from 1 to 46 months postoperatively. In patients with homograft aortic valve replacement, 76 patients (91.5%) had trivial to mild aortic regurgitation, while 7 patients (8.4%) had important aortic regurgitation. In patients with the Ross procedure, 78 patients (89.6%) had trivial to mild regurgitation. Moderate to severe aortic regurgitation was present in 9 patients (10.3%), all of whom had rheumatic heart disease and were young (< 30 years at surgery). We conclude that homografts and autografts provide an excellent substitute for the diseased aortic valve. Young age (< 30 years) with rheumatic etiology is a major risk factor for early progressive aortic regurgitation in patients undergoing the Ross procedure.

Assessment of trabecular structure using high resolution CT images and texture analysis

PURPOSE

Our goal was to use high resolution (HR) CT images combined with texture analysis to investigate the trabecular structure of human vertebral specimens and to compare these techniques with bone mineral density (BMD) in the prediction of bone strength.

METHOD

HR CT images with a slice thickness of 1 mm were obtained of 28 bone cubes. Four different groups of texture analysis techniques were used to assess these images. In addition, quantitative CT (QCT) was performed and elastic modulus (EM) was determined biomechanically.

RESULTS

R2 between EM and BMD was 0.78 (p < 0.01). R2 values for EM versus most of the texture measures were also significant. Texture measures in addition to measures of BMD in a multivariate regression model significantly increased R2 up to 0.87.

CONCLUSION

In an experimental setting, texture parameters calculated using HR CT images correlated significantly with EM. Combining texture measures with BMD improved the prediction of EM significantly.

Carotid artery stents: early and intermediate follow-up with Doppler US

PURPOSE

To determine whether ultrasound (US) is a sensitive follow-up method after placement of a carotid artery stent for the detection of significant stenosis, occlusion, and other complications at early and intermediate follow-up.

MATERIALS AND METHODS

Doppler US examinations were performed after stent placement in 170 carotid arteries in 119 patients with angiographic correlation. Prospective diagnostic US criteria for stenosis were peak-systolic velocity greater than 1.25 m/sec, internal carotid artery (ICA) to common carotid artery (CCA) peak-systolic velocity ratio of greater than or equal to 3:1, and intrastent doubling of peak-systolic velocity. Retrospective criteria for stenosis were also applied: peak-systolic velocity greater than 1.7 m/sec, ICA end-diastolic velocity greater than 0.4 m/sec, ICA/CCA peak-systolic velocity ratio greater than 2.0, and ICA/CCA end-diastolic velocity ratio greater than 2.4.

RESULTS

Eighty-seven immediate and 83 intermediate (average, 7.3 months) follow-up US examinations were performed. Two stent occlusions were detected. One or more prospective US criteria were abnormal in 26 arteries with a stent. One or more retrospective criteria were positive in 47 arteries. Angiography showed corresponding findings, with only one significant stenosis (63%) in the ICA stents. Moderate collapse of a CCA stent was depicted at US.

CONCLUSION

Only one significant recurrent stenosis was detected, and no significant stenoses were missed at US. US successfully depicted carotid artery stent occlusion and a moderate stent collapse. Sensitivity in the detection of intrastent stenosis is promising. Further study to refine US criteria in a study with longer term follow-up is needed owing to the lack of significant recurrent stenosis in the intermediate follow-up group.

Subgingival temperature: relation to gingival crevicular fluid enzymes, cytokines, and subgingival plaque micro-organisms

There have been no reports on the relationship of subgingival temperature to specific gingival crevicular fluid (GCF) components. Therefore, the purpose of this cross-sectional study was to determine whether there was any relationship between subgingival temperature and GCF levels of neutrophil elastase (NE), myeloperoxidase (MPO), beta-glucuronidase (BG), interleukin-1 alpha (IL-1), and interferon alpha (IFN). Furthermore, another objective was to confirm an association of subgingival temperature with clinical parameters and specific subgingival plaque micro-organisms as has been reported earlier. 27 human subjects each having healthy (n = 50), gingivitis (n = 59) and periodontitis (n = 53) sites were evaluated. The plaque index (PI), subgingival temperature, probing depth, attachment loss, bleeding index and gingival index were measured. GCF was sampled following the measurement of the PI and removal of the supragingival plaque. GCF samples were assayed for the enzymes NE, BG, MPO and the cytokines IFN-alpha and IL-1 alpha. A sterile Gracey curette was utilized at each sampled site to collect subgingival plaque. The plaque samples were evaluated using an immunoassay. Subgingival temperature was found to directly correlate with all clinical parameters (p < 0.001). Significant, albeit not large, correlations were found between subgingival temperature and NE (r = 0.35, p < 0.001), MPO (r = 0.26, p < 0.001) and BG (r = 0.23, p < 0.01). Temperature was found to correlate positively with E. corrodens (r = 0.33, p < 0.02) and F. nucleatum (r = 0.25, p < 0.05) but not with P. intermedia (r = 0.02, p = 0.9), P. gingivalis (r = 0.20, p = 0.1) and A. actinomycetemcomitans (r = 0.01, p > 0.9). In conclusion, subgingival temperature is correlated with the GCF enzymes, NE, MPO and BG as well as the clinical parameters and specific plaque micro-organisms associated with periodontal disease.

Locomotion and stereotypy induced by scopolamine: contributions of muscarinic receptors near the pedunculopontine tegmental nucleus

In this study, we test whether blockade of muscarinic receptors near mesopontine cholinergic cell groups may contribute to locomotor activation induced by scopolamine. Unilateral or bilateral injections of scopolamine (10-150 micrograms) into the pedunculopontine tegmental nucleus (PPT) increased horizontal locomotion by 2-15 times in a dose-related way. Unilateral or bilateral injections of scopolamine into the PPT increased stereotypic behaviors (such as sniffing in one location or over large areas), self-biting and grooming. Carbachol (4 micrograms) injected into PPT reduced locomotion for 20 min, followed by 70 min of increased locomotion. When carbachol (4 micrograms) was injected into the PPT before scopolamine (3 mg/kg, i.p.), the activating effect of scopolamine was attenuated, but not when carbachol was injected after scopolamine. Therefore, carbachol appears to compete with scopolamine for muscarinic receptors near the PPT that mediate locomotor activating effects of systemic scopolamine. Haloperidol (0.1 mg/kg, i.p.) also attenuated the stereotypy and locomotion induced by scopolamine in the PPT. We hypothesize that scopolamine acts by blocking muscarinic receptors on mesopontine cholinergic neurons, thereby disinhibiting cholinergic neurons that can activate dopamine neurons.

Interaction of factor IXa with factor VIIIa. Effects of protease domain Ca2+ binding site, proteolysis in the autolysis loop, phospholipid, and factor X

We previously identified a high affinity Ca2+ binding site in the protease domain of factor IXa involving Glu235 (Glu70 in chymotrypsinogen numbering; hereafter, the numbers in brackets refer to the chymotrypsin equivalents) and Glu245[80] as putative ligands. To delineate the function of this Ca2+ binding site, we expressed IXwild type (IXWT), IXE235K, and IXE245V in 293 kidney cells and compared their properties with those of factor IX isolated from normal plasma (IXNP); each protein had the same Mr and gamma-carboxyglutamic acid content. Activation of each factor IX protein by factor VIIa.Ca2+.tissue factor was normal as analyzed by sodium dodecyl sulfate-gel electrophoresis. The coagulant activity of IXaWT was approximately 93%, of IXaE235K was approximately 27%, and of IXaE245V was approximately 4% compared with that of IXaNP. In contrast, activation by factor XIa.Ca2+ led to proteolysis at Arg318-Ser319[150-151] in the protease domain autolysis loop of IXaE245V with a concomitant loss of coagulant activity; this proteolysis was moderate in IXaE235K and minimal in IXaWT or IXaNP. Interaction of each activated mutant with an active site probe, p-aminobenzamidine, was also examined; the Kd of interaction in the absence and presence (in parentheses) of Ca2+ was: IXaNP or IXaWT 230 microM (78 microM), IXaE235K 150 microM (145 microM), IXaE245V 225 microM (240 microM), and autolysis loop cleaved IXaE245V 330 microM (350 microM). Next, we evaluated the apparent Kd (Kd,app) of interaction of each activated mutant with factor VIIIa. We first investigated the EC50 of interaction of IXaNP as well as of IXaWT with factor VIIIa in the presence and absence of phospholipid (PL) and varying concentrations of factor X. At each factor X concentration and constant factor VIIIa, EC50 was the free IXaNP or IXaWT concentration that yielded a half-maximal rate of factor Xa generation. EC50 values for IXaNP and IXaWT were similar and are as follows: PL-minus/X-minus (extrapolated), 2.8 microM; PL-minus/X-saturating, 0.25 microM; PLplus/X-minus, 1.6 nM; and PL-plus/X-saturating, 0.09 nM. Further, Kd,app of binding of active site-blocked factor IXa to factor VIIIa was calculated from its ability to inhibit IXaWT in the Tenase assay. Kd,app values in the absence and presence (in parentheses) of PL were: IXaNP or IXaWT, 0. 19 microM (0.07 nM); IXaE235K, 0.68 microM (0.26 nM); IXaE245V, 2.5 microM (1.35 nM); and autolysis loop-cleaved IXaE245V, 15.6 microM (14.3 nM). We conclude that (a) PL increases the apparent affinity of factor IXa for factor VIIIa approximately 2,000-fold, and the substrate, factor X, increases this affinity approximately 10-15-fold; (b) the protease domain Ca2+ binding site increases this affinity approximately 15-fold, and lysine at position 235 only partly substitutes for Ca2+; (c) Ca2+ binding to the protease domain increases the S1 reactivity approximately 3-fold and prevents proteolysis in the autolysis loop; and (d) proteolysis in the autolysis loop leads to a loss of catalytic efficiency with retention of S1 binding site and a further approximately 8-fold reduction in affinity of factor IXa for factor VIIIa.

Excretion of clofazimine in human milk in leprosy patients

Clofazimine is an important and effective constituent of multi drug therapy for leprosy. A study has been conducted to determine the distribution of clofazimine in maternal milk so that the safety of breast-feeding during maternal ingestion of the drug can be ascertained. Eight female leprosy patients (LL/BL) on clofazimine, 50 mg daily or 100 mg on alternate days for 1-18 months, (mean 5.0 +/- 1.81 months; median 3.25 months) and in the early lactating phase were studied. Blood samples and milk specimens were collected 4-6 hr after the last daily dose. Clofazimine was assayed in the milk and plasma samples by HPTLC. Mean plasma and milk clofazimine levels were 0.9 +/- 0.03 micrograms/ml and 1.33 +/- 0.09 micrograms/ml respectively. The ratio of milk to plasma drug concentration ranged from 1.0 to 1.7 with a mean of 1.48 +/- 0.08. The amount of drug ingested by the infants was 0.199 +/- 0.013 mg/kg/day which represented 22.1 +/- 1.9% of the maternal dose.

Interaction of calcium with native and decarboxylated human factor X. Effect of proteolysis in the autolysis loop on catalytic efficiency and factor Va binding

Human factor X is a two-chain, 58-kDa, vitamin K-dependent blood coagulation zymogen. The light chain of factor X consists of an NH2-terminal gamma-carboxyglutamic acid (Gla) domain, followed by a few helical hydrophobic residues and the two epidermal growth factor-like domains, whereas the heavy chain contains the serine protease domain. In this study, native factor X was found to contain three classes of Ca2+-binding sites: two high affinity (Kd 100 +/- 30 microM), four intermediate affinity (Kd 450 +/- 70 microM), and five to six low affinity (Kd 2 +/- 0.2 mM). Decarboxylated factor X in which the Gla residues were converted to Glu retained the two high affinity sites (Kd 140 +/- 20 microM). In contrast, factor X lacking the Gla domain as well as a part of the helical hydrophobic residues (des-44-X) retained only one high affinity Ca2+-binding site (Kd 130 +/- 20 microM). Moreover, a synthetic peptide composed of residues 238-277 (58-97 in chymotrypsinogen numbering) from the protease domain of factor X bound one Ca2+ with high affinity (Kd 150 +/- 20 microM). From competitive inhibition assays for binding of active site-blocked factor Xa to factor Va in the prothrombinase complex, the Kd for peptide-Va interaction was calculated to be approximately 10 microM as compared with 30 pM for factor Xa and approximately 1.5 microM for decarboxylated factor Xa. A peptide containing residues 238-262(58-82) bound Ca2+ with reduced affinity (Kd approximately 600 microM) and did not inhibit Xa:Va interaction. In contrast, a peptide containing residues 253-277(73-97) inhibited Xa:Va interaction (Kd approximately 10 microM) but did not bind Ca2+. In additional studies, Ca2+ increased the amidolytic activity of native and des-44-Xa toward a tetrapeptide substrate (benzoyl-Ile-Glu-Gly-Arg-p-nitroanilide) by approximately 1.6-fold. The half-maximal increase was observed at approximately 150 microM Ca2+ and the effect was primarily on the kcat. Ca2+ also significantly protected cleavage at Arg-332-Gln-333(150-151) in the protease domain autolysis loop. Des-44-Xa in which the autolysis loop was cleaved possessed </=5% of the amidolytic activity of the noncleaved form; however, the S1 binding site was not affected, as determined by the p-aminobenzamidine binding. Additionally, autolysis loop-cleaved, active site-blocked native factor Xa was calculated to have approximately 10-fold reduced affinity for factor Va as compared with that of the noncleaved form.

Volumetric quantitative computed tomography of the proximal femur: precision and relation to bone strength

We have developed a three-dimensional computed tomography (CT) scanning and image analysis method for measurement of trabecular and integral bone mineral density (BMD) and geometry in automatically determined femoral-neck and trochanteric subregions of the proximal femur. We measured the correlation of the density and geometry variables to femoral strength assessed in vitro under loading simulating a single-limb condition and a fall to the side. While BMD alone accounted for 48%-77% of the variability in strength for the stance loading configuration, femoral neck cross-sectional area (minCSA) and femoral neck axis length (FNAL) also contributed independently to femoral strength, and a combination of BMD and geometry variables explained 87%-93% of the variance in the data. For the fall loading configuration, trochanteric trabecular BMD alone explained 87% of the variability of strength. The reproducibility in vivo of the technique was assessed in a group of seven postmenopausal women, who underwent repeat scans with repositioning. For trabecular BMD, the precision was 1.1% and 0.6% for the femoral neck and trochanteric subregions, respectively, compared to 3.3% and 1.6% for the corresponding integral envelopes. Thus, trabecular BMD measurements were reproducible and highly correlated to biomechanical strength measurements. These results support further exploration of quantitative CT for assessment of osteoporosis at the proximal femur.

Palmaz stent compression in patients following carotid artery stenting

Carotid artery stenting is being investigated as a therapeutic strategy for the management of bifurcation stenosis. Palmaz stents were deployed successfully in the carotid arteries of 112 patients using high-pressure balloon inflations. In 11 out of 70 patients who came for 6-mo follow-up angiography, a stent collapse was noted. Carotid ultrasound was able to detect stent collapse in only two patients at follow-up. Only one patient who had collapse of stent along its entire length was symptomatic at follow-up. Repeat balloon angioplasty was performed in 5 patients, 3 of whom had a Wallstents deployed within the Palmaz stent.

CONCLUSION

Stent collapse was observed in a significant number of Palmaz stents within 6 mo of placement in the carotid arteries. These observations should influence the choice of stents for the treatment of extracranial carotid disease.

A retrospective study of etiopathological and preventive factors in a burns unit in Saudi Arabia

A 10-bed state-of-the-art burns unit was commissioned at King Fahd Specialist Hospital, Buraidah, Al-Qassim and the first 90 cases admitted to the unit over an 18-month period were analysed. The mean age (+/-SD) was 14.9 (+/-1.5) years with a range of 6 months-55 years. Fifty-one per cent were males, 52.2 per cent were children under 12 years of age and of these 85.1 per cent were under 5 years of age. Scalds and flames accounted for 90 per cent of the burns. Domestic burns formed the majority of cases, 64 (71 per cent), and most patients were admitted within the first 24 h (76 per cent). The mean (+/-SE) of the total body surface area (TBSA) was 23 per cent (+/-2.4) with a range of 3-98 per cent. The mean hospital stay for the whole group was 16.4 days. Overall mortality was five patients (5.6 per cent) while the mortality in critical burns was 14.3 per cent. TBSA was found to be the main factor influencing mortality. This study highlights the important factors that affect the outcome in this unit. Factors that can improve the morbidity and mortality rates in patients are highlighted. The study also reveals certain patterns and etiological factors in the Qassim region. Prevention by education through a national campaign remains the keystone in reducing the incidence of burns particularly in children and the maximization of resources.