Reexamination of hip biomechanics during unilateral stance

The Koch model, as initially proposed, is an incomplete representation of hip biomechanics during the unilateral support phase of midstance. The model proposed by this study includes the iliotibial band as a tension band lateral to the femoral shaft. During the unilateral support phase of gait, the iliotibial band creates compression loading laterally and medially throughout the femur distal to the greater trochanteric apophysis. Bench testing of cadaveric femora with and without protheses demonstrated the necessity of a total hip replacement femoral component to engage the proximal lateral femoral cortex as an additional area of support against subsidence. This model, byproviding a more complete and accurate depiction of hip biomechanics, creates a more valid basis for analysis of hip function.     

Incipient left ventricular rupture complicating anomalous left coronary artery

A 4-month-old girl presented with 2 weeks of symptoms and physical signs of heart failure. Echocardiography demonstrated marked left ventricular dilation, thinning of the myocardium with anterolateral akinesis, mitral regurgitation, a moderate pericardial collection, and an anomalous left coronary artery from the pulmonary artery. At operation there was a tense hemopericardium and a site of imminent rupture through a transmural anterior infarction. The anomalous artery was reimplanted in the ascending aorta, and an extensive infarct resection and ventricular repair performed. Support with a left ventricular assist device was required for 3 days, but the infant subsequently made a satisfactory recovery. Left ventricular rupture is a very rare complication of this lesion, but should be considered if there is evidence of a pericardial collection.     

Multiple single units and population responses during inhibitory gating of hippocampal auditory response in freely-moving rats

Paired clicks were presented to awake, freely-moving rats to examine neuronal activity associated with inhibitory gating of responses to repeated auditory stimuli. The rats had bundles of eight microwires implanted into each of four different brain areas: CA3 region of the hippocampus, medial septal nucleus, brainstem reticular nucleus, and the auditory cortex. Single-unit recordings from each wire were made while the local auditory-evoked potential was also recorded. The response to a conditioning stimulus was compared to the response to a test stimulus delivered 500 ms later: the ratio of the test response to the conditioning response provided a measure of inhibitory gating. Auditory-evoked potentials were recorded at all sites. Overall, brainstem reticular nucleus neurons showed the greatest gating of local auditory-evoked potentials, while the auditory cortex showed the least. However, except for the auditory cortex, both gating and non-gating of the evoked response were recorded at various times in all brain regions. Gating of the hippocampal response was significantly correlated with gating in the medial septal nucleus and brainstem reticular nucleus, but not the auditory cortex. Single-unit neuron firing in response to the clicks was most pronounced in the brainstem reticular nucleus and the medial septal nucleus, while relatively few neurons responded in the CA3 region of the hippocampus and the auditory cortex. Taken together, these data support the hypothesis that inhibitory gating of the auditory-evoked response originates in the non-lemniscal pathway and not in cortical areas of the rat brain.     

Predictability of PSA failure in prostate cancer by computerized cytometric assessment of tumoral cell proliferation

OBJECTIVES: To evaluate the relationship of DNA ploidy and cell proliferation (CP) with Gleason score (GS) and clinical outcome in prostate cancer. METHODS: Sixteen patients with benign prostatic hyperplasia (BPH) and 65 patients with prostate cancer classified by GS (four groups: 2 to 4, 5 to 6, 7, and 8 to 10) were studied. All patients with carcinoma underwent prostatectomy and were separated into prostate-specific antigen (PSA) failure and nonfailure groups (failure if PSA 0.1 ng/mL or more three times after surgery). Tumoral CP (Ki-67 inmunostaining and SG2M phase) and DNA ploidy were evaluated by computerized cytometry. RESULTS: BPH were diploid with low CP (8% SG2M cells or less). Carcinomas were either diploid with high CP (greater than 8% SG2M cells) or aneuploid. CP was significantly higher (P <0.001) in tumors with GS 7 or greater than in tumors with GS less than 7 (mean percent Ki-67 cells 18.3% versus 7.8%, respectively). PSA failure increased with GS (7.1% in GS 2 to 4, 21% in GS 5 to 6, 28.6% in GS 7, and 50% in GS 8 to 10), as well as with aneuploidy (18.5% in diploid tumors versus 72.7% in aneuploid tumors). Those experiencing PSA failure had significantly higher (P <0.001) CP than those not failing (mean percent Ki-67 cells 24% and mean percent SG2M 30.4% versus 8.7% and 13.5%, respectively). Cox regression analysis showed GS, DNA ploidy, Ki-67, and SG2M to each be univariately prognostic for time to PSA failure; however, Ki-67 and SG2M were more highly significant (P <0.0001 for both) than GS (P = 0.007) or DNA ploidy (P = 0.002). After adjusting for either SG2M or Ki-67 measures of CP, neither ploidy nor GS contained additional prognostic value. CONCLUSIONS: Tumor CP and DNA ploidy can be reliably determined in prostate cancer by computerized cytometry. On the basis of our preliminary results, CP correlates well with GS and predicts PSA failure better than DNA ploidy or GS.     

Social support, social selection and self-assessed health status: results from the veterans health study in the United States

This study provided a comprehensive assessment of the association between social support and health using longitudinal data from the Veterans Health Study. Unlike previous studies which examined the relationship between one single domain of social support with either mental or physical health, the present study assessed the effects of three different domains of social support on multiple measures of health. The findings of the study indicated that social support tended to mediate the deleterious effects of non-military traumatic events; whereas the adverse consequences of traumatic events experienced in the military were not affected by social support, suggesting that stressors associated with combat had a long lasting effect on the health status of veterans. The study results revealed that compared with those with better health, respondents with poor health were more likely to have lower levels of social support, suggesting that poor health might be a barrier to a person's ability to participate and/or maintain social relationships. The study also showed that different types of social support had varying beneficial effects on different measures of health. While perceived support had a strong effect on all the measures of health (except alcoholism) included in the study, living arrangement had a significant effect on post-traumatic stress disorder or physical health and participation in group activities had a strong effect only on physical functioning. The results of the study highlight the need for future research to determine whether particular types of social support affect various aspects of health differently. This simultaneous focus on multiple support functions and health outcomes is important because it provides insight into the mechanisms linking social support to health.     

Murine transgenic cells lacking DNA topoisomerase IIbeta are resistant to acridines and mitoxantrone: analysis of cytotoxicity and cleavable complex formation

Murine transgenic cell lines lacking DNA topoisomerase II (topo II)beta have been used to assess the importance of topo IIbeta as a drug target. Western blot analysis confirmed that the topo IIbeta -/- cell lines did not contain topo IIbeta protein. In addition, both the topo IIbeta +/+ and topo IIbeta -/- cell lines contained similar levels of topo IIalpha protein. The trapped in agarose DNA immunostaining assay (TARDIS) was used to detect topo IIalpha and beta cleavable complexes in topo IIbeta -/- and topo IIbeta +/+ cells. These results show that both topo IIalpha and beta are in vivo targets for etoposide, mitoxantrone, and amsacrine (mAMSA) in topo IIbeta +/+ cells. As expected, only the alpha-isoform was targeted in topo IIbeta -/- cells. Clonogenic assays comparing the survival of topo IIbeta -/- and topo IIbeta +/+ cells were carried out to establish whether the absence of topo IIbeta caused drug resistance. Increased survival of topo IIbeta -/- cells compared with topo IIbeta +/+ cells was observed after treatment with amsacrine (mAMSA), methyl N-(4'-[9-acridinylamino]-2-methoxyphenyl) carbamate hydrochloride (AMCA), methyl N-(4'-[9-acridinylamino]-2-methoxyphenyl)carbamate hydrochloride (mAMCA), mitoxantrone, and etoposide. These studies showed that topo IIbeta -/- cells were significantly more resistant to mAMSA, AMCA, mAMCA, and mitoxantrone, than topo IIbeta +/+ cells, indicating that topo IIbeta is an important target for the cytotoxic effects of these compounds.     

Primary infiltrating signet ring carcinoma of the eyelids

A 61-year old man presented with a five-year history of a swelling initially developing in his right lower lid that progressed to involve the lateral canthal skin and eventually the upper lid and anterior orbit. He was discovered to have an infiltrating, poorly differentiated, mucin-producing carcinoma. Systemic work-up failed to disclose a visceral malignancy, and it was concluded that his tumor was primary in the lids, arising from an adnexal sweat gland. Three other reports in the literature also share almost identical clinical and pathologic features, in that all of the earlier reports dealt with middle-aged or elderly men who had diffusely indurated lids. Histopathologically, the tumor cells grow diffusely in a sclerotic stroma, and resemble the "histiocytoid" variant of metastatic breast carcinoma to the lids in women. Ultrastructural studies in our case point toward an apocrine origin, although earlier authors have favored an eccrine origin. Despite its indolent clinical course, the tumor is capable of producing regional and distant metastases on long-term follow-up. Complete local excision, possibly necessitating radical surgery, is probably the preferred method of treatment, but local radiotherapy may have a beneficial effect in retarding spread of the disease.