CD4 is expressed by epidermal Langerhans' cells predominantly as covalent dimers

Langerhans' cells (LC) of skin are CD4 expressing, dendritic, antigen-presenting cells, that are essential for activation of primary immune responses and are productively infected by HIV. We have shown previously that lymphocytes and monocytes express CD4 both as monomers and covalently linked homodimers. In those cells the 55-kDa monomer structure predominates. LC in un-fractionated human epidermal cell (EC) suspension also expresses both forms of CD4, but in EC the dimer form is predominant. Because isolation of LC into single cell suspension by trypsin, as is routinely used for LC isolation, degrades CD4, a systematic study for an alternate procedure for LC isolation was performed. Thus it was found that collagenase blend F treatment can efficiently release LC into suspension, under conditions of only minimal degradation of control soluble recombinant CD4 or CEM-T4 or THP-1 cell CD4, or importantly of LC surface CD4. SDS-PAGE immunoblotting of purified LC extracted from EC by collagenase confirmed CD4 structure as predominantly 110-kDa dimers, with only minimal 55-kDa monomers. The suitability of LC prepared thus for functional studies was demonstrated with binding of functional ligand HIV gp120. It remains to be determined, however, why tissue embedded LC express mainly CD4 dimers, but single-celled blood lymphocytes and monocytes mainly monomers.     

Thoracic spine compression fracture after TASER activation

The TASER is a less lethal weapon seeing increased use by police jurisdictions across the country. As a result, subjects of TASER use are being seen with increasing frequency in emergency departments across the country. The potential injury patterns of the device are important for emergency physicians to understand. This report describes the case of an officer who complained of back pain after a single 5-s TASER discharge during a routine training exercise. Subsequent evaluation led to the diagnosis of an acute thoracic vertebral compression fracture. We discuss the potential mechanisms of injury in this case. Because we were unable to find any cases like this in our review of TASER-related injuries, we liken it to compression fractures that have been documented after seizures. We recommend that physicians consider obtaining back radiographs to rule out a vertebral compression fracture in any individual who has sustained a TASER discharge and has ongoing or persistent back pain.     

Epidemiology of spine trauma in an Irish regional trauma unit: a 4-year study

Currently there is a lack of information on the full spectrum of spine trauma presenting to medical services in a defined geographic area. This study analyses the aetiology and demographics of a cohort of spine trauma in the West of Ireland. A regional trauma unit has been investigated for a 51-month period. Two hundred and eighty-five cases admitted with spine trauma were documented. The annual incidence of traumatic spinal injury was 19.54 cases/100,000 persons per year. Falls and low-energy trauma are shown to constitute a significant proportion of all cases (60.35%). Injury at greater than one level is frequently present. The highest peak of injury occurred in the 20-24-year-old age group (11.58%). A second peak occurred at 75-79 years of age (7.37%). The commonest cause of neurological injury was falls (n=9; 64.3%). This spine trauma register has provided valuable insights into the patterns of injury encountered in spine trauma patients in this region. It may act as a blueprint for a national spine trauma register and highlights the importance of patient education and injury prevention strategies.     

Death or hospitalization of patients on chronic hemodialysis is associated with a physician-based diagnosis of depression

Depressive symptoms, assessed using a self-report type of questionnaire, have been associated with poor outcomes in dialysis patients. Here we determined if depressive disorders diagnosed by physicians are also associated with such outcomes. Ninety-eight consecutive patients on chronic hemodialysis underwent the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders administered by a physician. Depression was diagnosed in about a quarter of the patients. Associations adjusted for age, gender, race, time on dialysis and co-morbidity were determined using survival analysis. Using time to event (death or hospitalization) models of analysis the hazard ratios were 2.11 and 2.07 in unadjusted and adjusted models respectively. The finding of poor outcome using a formal structured physician interview suggests that a prospective study is needed to determine whether treatment of depression affects clinical outcomes.     

Race, presenting signs and symptoms, use of carotid artery imaging, and appropriateness of carotid endarterectomy.

BACKGROUND AND PURPOSE: We sought to determine whether there are racial differences in use of carotid artery imaging after controlling for clinical factors and to ascertain racial differences in presenting signs and symptoms and overall appropriateness for carotid endarterectomy (CE). METHODS: We performed a retrospective cohort study of 803 patients older than 45 years, hospitalized between 1991 and 1994 at any of 4 Veterans Affairs Medical Centers, with a discharge diagnosis of transient ischemic attack or ischemic stroke. Clinical data were abstracted from the medical record, including presenting symptoms, diagnostic test results, and use of surgical procedures. Appropriateness for CE was determined according to RAND criteria. RESULTS: Black patients were more likely than white patients to present with stroke (78% versus 55%) but less likely to present with transient ischemic attack (22% versus 45%; P=0.001). There was no racial difference in medical comorbidity or preoperative risk. Black patients were less likely to have an imaging study of their carotid arteries (67% versus 79%; P=0.001). Race remained an independent predictor of imaging after adjustment for clinical factors (odds ratio=1.50; 95% CI, 1.06 to 2.13). Because of higher prevalence of significant carotid artery stenosis, whites were significantly more likely than blacks to be assessed as appropriate candidates for surgery with the use of RAND criteria (18% versus 4%; P=0.001). CONCLUSIONS: Use of carotid artery imaging, a critical step in determining eligibility for CE, is influenced by the patient's race after controlling for clinical presentation. Adjustment for appropriateness of CE reduces but does not eliminate the importance of race.