A study of stiffness protocol as exemplified by testing of a burst fracture model in sagittal plane

STUDY DESIGN: An in vitro biomechanical study of lumbar spine segments. OBJECTIVE: To study the characteristics of the stiffness test protocol. SUMMARY OF BACKGROUND DATA: In an in vitro study using a flexibility protocol, forces are applied and motions are measured; no center of rotation needs to be specified. In a study using a stiffness protocol, the forces are measured and the motions are applied. This does require the center of rotation to be specified. Many biomechanical studies of the spine are available, but there is lack of clarity concerning which of these two test protocols is appropriate to achieve a certain study goal. METHODS: Five-vertebrae lumbar spine specimens with burst fractures in the middle vertebrae (L1) were used. Specially designed apparatus applied flexion and extension rotations around five centers of rotations located on anteroposterior line through the middle of L1. Maximum moment of 4 Nm was applied. RESULTS: The authors found load-displacement curves, ranges of motion, and neutral zones obtained at the five centers of rotations to be markedly different. The center of rotation located at the posterior longitudinal ligament produced large range of motion and neutral zones in comparison to the centers of rotation located at the anterior longitudinal ligament and the spinous process tip (P<0.01). CONCLUSIONS: The stiffness protocol requires that a center of rotation be specified. Shown here is the significant variability in the load-displacement curves, depending on the choice of the location of the center of rotation. Certain center of rotation locations may block the natural motions of the spine and may result in tissue damage.     

Pin loosening in a halo-vest orthosis: a biomechanical study

STUDY DESIGN: The cranial pin force history of a halo-vest orthosis was measured using an instrumented halo in a clinical study with three patients. Pin force values at the time of halo-vest application and at subsequent clinical visits during the halo-vest wear period were compared. OBJECTIVES: To document the pin force reduction in the cranial pins of a halo-vest orthosis in vivo. SUMMARY OF BACKGROUND DATA: The halo-vest is an orthosis commonly used to immobilize and protect the cervical spine. An important problem with halo-vest use is pin loosening. There have been no previous reports of pin force history in vivo. METHODS: A custom-built strain-gauged, open-ring halo was used to measure the compressive force and superiorly-inferiorly directed shear forces produced at the tips of the two posterior pins. The instrumented halo was applied to three patients with cervical spine fractures. Pin force measurements were recorded at the time of halo application and at subsequent follow-up visits during the entire treatment period. RESULTS: A mean compressive force of 343 +/- 64.6 N was produced at the pin tips during halo application with the patient in a supine position. On average, the compressive forces decreased by 83% (P = 0.002) during the typical halo-vest wear period. The compressive forces were substantially greater than the shear forces, which averaged only -11+/-30.2 N at the time of halo application and which did not change significantly with time. CONCLUSIONS: The study confirmed the hypothesized decrease in the compressive pin forces with time. All patients had developed at least some clinical symptoms of pin loosening at the time of halo-vest removal.     

Adjustment to breast cancer: age‐related differences in coping and emotional distress

Women who are diagnosed with breast cancer are at high risk for experiencing affective distress; however, previous research suggests that older women may be less likely than younger women to experience extreme distress. Two issues remain unclear regarding age and affective distress: (a) the psychological processes that account for the association of age and distress, and (b) whether this association remains stable over the course of treatment and recovery from breast cancer. This study investigated symptoms of anxiety and depression in 80 women ages 36–80 years old with newly diagnosed breast cancer near the time of their diagnosis and at 3 and 6 months postdiagnosis. Disease severity and coping style were also examined. Symptoms of anxiety/depression and age were negatively correlated near the time of diagnosis. Path analysis controlling for disease severity revealed that coping involving the ventilation of emotion fully mediated the effect of age on symptoms of anxiety and depression. However, the association of age with symptoms of anxiety/depression was no longer significant at 3 and 6 months postdiagnosis, although emotional ventilation still predicted greater emotional distress at 6 months. These findings suggest that age is a salient factor to consider in the psychological adjustment of women with breast cancer near the time of initial diagnosis, with younger women exhibiting greater affective distress and a tendency to engage in less adaptive ways of coping. However, younger and older women do not differ in their adjustment over the subsequent course of their treatment and initial recovery. The use of emotional ventilation coping remains associated with poorer adjustment, independent of patients age.     

Sentinel node biopsy for breast cancer: showtime or dress rehearsal?

INTRODUCTION: Sentinel lymph node biopsy (SLNB) may prove superior to axillary node dissection (AND) for breast cancer staging. At issue is whether existing clinical data support performance of SLNB without AND at this time. DISCUSSION: The various methods of SLNB are discussed in detail. SLNB using radiocolloids and surgical probes (with or without blue dye) yields superior SLN localization rates as compared to blue dye alone. However, the incidence of false-negative SLNB is variable with all methods and frequently 10% or higher (11.4% in the only published multicenter study). CONCLUSIONS: Outside of a clinical trial, SLNB should be performed in addition to, not instead of, AND. The sensitivity of pathological staging is enhanced and nonaxillary SLNs are identified, while concomitant AND apprehends all false-negative SLNBs. Two prospective randomized cooperative trials provide excellent educational, training and research opportunities for North American breast surgeons as they gain experience with this new, promising staging procedure.     

Experimental study on cross‐reactivity of α‐arbutin toward p‐phenylenediamine and hydroquinone in guinea pigs

Hydroquinone (HQ) has been used as a skin‐lightening cosmetic ingredient, while it has been known that HQ shows sensitizing potential and cross‐reactivity toward a strong sensitizer, p‐phenylenediamine (PPD). α‐Arbutin, a glycoside of HQ (4‐hydroxyphenyl α‐D‐glucopyranoside), is used worldwide as a skin‐lightening agent. The aim of this study was to evaluate the cross‐reactivity of α‐arbutin toward PPD and HQ. All tests were performed using the guinea pig maximization test. In experiments on the cross‐reactivity of α‐arbutin or HQ to PPD, six animals in each group were induced with PPD at 0.1% by i.d. injection and at 1.0% by topical application. The animals were challenged with α‐arbutin, HQ or PPD (as a positive control) at concentrations of 0.01%, 0.05% and 0.1%. In experiments on the cross‐reactivity of α‐arbutin to HQ, four animals in each group were induced with HQ at 2% by i.d. injection and at 1% by topical application. The animals were challenged with α‐arbutin or HQ (as a positive control) at concentrations of 0.2%, 2% and 20%. The cross‐reactivity toward PPD was observed with HQ (4/6) only at 0.1% challenge. However, α‐arbutin showed no apparent cross‐reactivity to either PPD or HQ even at their highest challenge concentrations. Potent sensitization was observed with PPD (6/6) even at 0.01% challenge and with HQ (3/4) at 0.2%. In conclusion, glycosylation of HQ remarkably reduced the sensitization potency of HQ and the cross‐reactivity of HQ to PPD.     

Why perform randomized clinical trials for sentinel node surgery for breast cancer?

Long-term outcome of sentinel node surgery without axillary dissection has not been established. To that extent the therapeutic outcome of sentinel node surgery is unknown. Two important clinical trials are under way that are designed to compare sentinel node surgery without axillary dissection to axillary dissection. In partnership with the University of Vermont, the National Surgical Adjuvant Breast and Bowel Project is conducting a trial that will primarily compare node negative breast cancer cases. The American College of Surgeons Clinical Oncology Group is conducting a trial that randomizes node positive breast cancer patients. The primary endpoints of these clinical trials are survival, long-term regional control, and morbidity. At the conclusion of these trials it will be established within a narrow confidence interval whether sentinel node surgery alone provides the same important therapeutic benefits as axillary surgery but without the morbidity associated with axillary surgery.     

盆腔外子宫内膜异位症19例临床分析

目的 探讨盆腔外子宫内膜异位症的临床特征。方法收集本院1990年1月至2000年12月收治的19例盆腔外子宫内膜异位症患者的临床资料,分析其发病情况、临床表现、诊断、治疗及预后。结果 18例患者为育龄期妇女,1例为围绝经期妇女,平均年龄36.2岁。病变部位8例位于手术切口、宫颈及阴道穹隆6例、胃肠道2例、泌尿系统3例及其他部位1例。主要症状:8例有皮下结节伴经期疼痛、2例月经期血尿及排便痛等,5例无典型症状。术前诊断率较低(52.6％)。治疗以局部病灶切除为主,术后辅以药物治疗。结论盆腔外子宫内膜异位症原因较复杂,因临床表现不典型,术前诊断率不高,应注意原发症状与月经周期的关系,提高对本病的认识。治疗应以切除病灶、缓解症状、恢复功能为主。     

Right Ventricular Septal Pacing: A Comparative Study of Outflow Tract and Mid Ventricular Sites

Background: Prolonged right ventricle (RV) apical pacing is associated with left ventricle (LV) dysfunction due to dysynchronous ventricular activation and contraction. Alternative RV pacing sites with a narrower QRS compared to RV pacing might reflect a more physiological and synchronous LV activation. The purpose of this study was to compare the QRS morphology, duration, and suitability of RV outflow tract (RVOT) septal and mid‐RV septal pacing. Methods: Seventeen consecutive patients with indication for dual‐chamber pacing were enrolled in the study. Two standard 58‐cm active fixation leads were passed to the RV and positioned in the RVOT septum and mid‐RV septum using a commercially available septal stylet (model 4140, St. Jude Medical, St. Paul, MN, USA). QRS duration, morphology, and pacing parameters were compared at the two sites. The RV lead with less‐satisfactory electrical parameters was withdrawn and deployed in the right atrium. Results: Successful positioning of the pacing leads at the RVOT septum and mid‐RV septum was achieved in 15 patients (88.2%). There were no significant differences in the mean stimulation threshold, R‐wave sensing, and lead impedance between the two sites. The QRS duration in the RVOT septum was 151 ± 14 ms and in the mid‐RV septum 145 ± 13 ms (P = 0.150). Conclusions: This prospective observational study shows that septal pacing can be reliably achieved both in the RVOT and mid‐RV with active fixation leads using a specifically shaped stylet. There are no preferences in regard to acute lead performance or paced QRS duration with either position. (PACE 2010; 33:1169–1173)     

Enrichment with anti-cytokeratin alone or combined with anti-EpCAM antibodies significantly increases the sensitivity for circulating tumor cell detection in metastatic breast cancer patients

Introduction  

Circulating tumor cells (CTCs) are detectable in most cancer patients and they can meet an existing medical need to monitor cancer patients during a course of treatment and to help determine recurrent disease. CTCs are rarely found in the blood of cancer patients and enrichment is necessary for sensitive CTC detection. Most CTC enrichment technologies are anti-EpCAM antibody based even though CTC identification criteria are cytokeratin positive (CK⁺), CD45 negative (CD45^-) and 4'6-diamidino-2-phenylindole (nuclear stain) positive (DAPI⁺). However, some tumor cells express low or no EpCAM. Here we present a highly sensitive and reproducible enrichment method that is based on binding to anti-CK alone or a combination of anti-CK and anti-EpCAM antibodies.