Effects of distally fixated versus nondistally fixated leg extensor resistance training on knee pain in the early period after anterior cruciate ligament reconstruction.

BACKGROUND AND PURPOSE: Nondistally fixated (ie, what is often referred to as "open kinetic chain" [OKC]) knee extensor resistance training appears to have lost favor for some forms of rehabilitation due partly to concerns that this exercise will irritate the extensor mechanism. In this randomized, single-blind clinical trial, nondistally fixated versus distally fixated (ie, often called "closed kinetic chain" [CKC]) leg extensor training were compared for their effects on knee pain. SUBJECTS: Forty-three patients recovering from anterior cruciate ligament (ACL) reconstruction surgery (34 male, 9 female; mean age=29 years, SD=7.9, range=16-54). METHODS: Knee pain was measured at 2 and 6 weeks after ACL reconstruction surgery using visual analog scales in a self-assessment questionnaire and during maximal isometric contractions of the knee extensors. Between test sessions, subjects trained 3 times per week using either OKC or CKC resistance of their knee and hip extensors as part of their physical therapy. RESULTS: No differences in knee pain were found between the treatment groups. DISCUSSION AND CONCLUSION: Open kinetic chain and CKC leg extensor training in the early period after ACL reconstruction surgery do not differ in their immediate effects on anterior knee pain. Based on these findings, further studies are needed using different exercise dosages and patient groups.     

Gender-specific and developmental influences on the expression of rat organic anion transporters

Rat organic anion transporter 1 (Oat1), Oat2, and Oat3, members of the organic anion transporter family, transport some organic anions across cellular membranes. Previously, highest Oat1 and Oat3 mRNA expression was reported in kidney and Oat2 in liver. However, gender and developmental differences in Oat expression remain unknown. This study describes gender- and age-specific patterns of rat organic anion transporter expression in various tissues. Oat mRNA expression was evaluated in adult male and female Sprague-Dawley rat tissues, and developmental expression was also determined in kidneys of Sprague-Dawley rats ranging in age from days 0 through 45. Expression was quantified using branched-DNA signal amplification. Oat1 mRNA expression was primarily observed in kidney. Surprisingly, Oat2 mRNA expression was also highest in kidney rather than in liver. Moreover, considerably higher Oat2 levels were seen in female kidney as compared with male. Finally, Oat3 mRNA expression was highest in kidney of both genders, whereas a male-predominant pattern was observed in liver. At birth, all kidney Oat mRNA levels were low. Renal Oat1 expression gradually increased throughout development, approaching adult levels at 30 days of age, where at days 40 and 45 Oat1 levels were greater in males than females. Oat2 expression in kidney was minimal through day 30 but increased dramatically at day 35 in females only. Lastly, Oat3 mRNA expression in kidney matured earliest, rapidly increasing from birth through day 10. These data indicate that Oat mRNA expression is primarily localized to the kidney, and observed expression patterns may explain some previously recognized age- and gender-dependent toxicities associated with chemical exposure.     

Sensitivity analyses for average treatment effects when outcome is censored by death in instrumental variable models

Two problems that arise in making causal inferences for nonmortality outcomes such as bronchopulmonary dysplasia (BPD) are unmeasured confounding and censoring by death, ie, the outcome is observed only when subjects survive. In randomized experiments with noncompliance and no censoring by death, instrumental variable (IV) methods can be used to control for the unmeasured confounding. But, when there is censoring by death, the average causal treatment effect cannot be identified under usual assumptions but can be studied for a specific subpopulation by using sensitivity analysis with additional assumptions. However, evaluating the local average treatment effect (LATE) in observational studies with censoring by death problems while controlling for unmeasured confounding is not well studied. We develop a novel sensitivity analysis method based on IV models for studying the LATE. Specifically, we present the identification results under an additional assumption and propose a three-step procedure for the LATE estimation. Also, we propose an improved two-step procedure by simultaneously estimating the instrument propensity score (ie, the probability of instrument given covariates) and the parameters induced by the assumption. We show with simulation studies that the two-step procedure can be more robust and efficient than the three-step procedure. Finally, we apply our sensitivity analysis methods to a study on the effect of delivery at high-level neonatal intensive care units on the risk of BPD.     

Clinical, histopathologic, and radiographic indicators of malignancy in head and neck paragangliomas

Objective

The goal of this study is to review our series of head and neck paragangliomas to identify factors that may help in predicting malignancy.

Study Design

Case series with chart review.

Setting

Academic medical center.

Subjects and Methods

Subjects with head and neck paragangliomas at our institution from 1976 to current were reviewed. In addition to statistical comparisons of epidemiologic factors, pathologic and radiographic characteristics were reviewed.

Results

Of the 84 subjects, there were seven malignant paragangliomas (8%). Age was found to be significantly different between the benign and malignant subgroups, with an average age of 54 ± 16 and 40 ± 12 years, respectively (P = 0.02). Pain was a presenting complaint in five patients with benign disease (6%), and five of the seven malignant patients (71%) presented with pain, showing a significant association between pain and disease type (P < 0.0001). The odds ratio for a patient with pain having a malignant tumor was 36 (95% CI: 5.5-234). Enlarging neck mass was noted in all cases of malignant disease, but only in 31 percent of cases of benign disease (P < 0.0001). In a secondary analysis of carotid body tumors alone, enlarging neck mass was not found to be significant between benign and malignant disease (P = 0.14). However, pain continued to be significantly different, with 67 percent of malignant lesions demonstrating pain, compared with only 11 percent of benign lesions (P = 0.01).

Conclusion

This study suggests that pain, a rapidly enlarging neck mass, and younger age are predictive factors of underlying malignancy, which should prompt one to consider an aggressive diagnostic and management approach.