Impairment in cognitive and exercise performance during prolonged antarctic residence: effect of thyroxine supplementation in the polar triiodothyronine syndrome

Humans who work in Antarctica display deficits in cognition, disturbances in mood, increased energy requirements, a decline of thyroid hormone products, and an increase of serum TSH. We compared measurements in 12 subjects, before deployment (baseline), with 11 monthly studies during Antarctic residence (AR). After 4 months of AR (period 1), half of the subjects (T(4) group) received L-thyroxine [64 nmol.day(-)(1) (0.05 mg.day(-)(1))]; and the other half, a placebo (placebo group) for the next 7 months of AR (period 2). During period 1, there was a 12.3 +/- 5.1% (P < 0.03) decline on the matching-to-sample (M-t-S) cognitive task and an increase in depressive symptoms, compared with baseline. During the intervention in period 2, M-t-S scores for the T(4)-treated group returned to baseline values; whereas the placebo group, in contrast, showed a reduced M-t-S score (11.2 +/- 1.3%; P < 0.0003) and serum free T(4) (5.9 +/- 2.4%; P < 0.02), compared with baseline. The change in M-t-S score was correlated with the change in free T(4) (P < 0.0003) during both periods, and increases in serum TSH preceded worsening scores in depression, tension, anger, lack of vigor, and total mood disturbance (P < 0.001) during period 2. Additionally, the submaximal work rate for a fixed O(2) use decreased 22.5 +/- 4.9% in period 1 and remained below baseline in period 2 (25.2 +/- 2.3%; P < 0.005) for both groups. After 4 months of AR, the L-thyroxine supplement was associated with improved cognition, which seems related to circulating T(4). Submaximal exercise performance decrements, observed during AR, were not changed with this L-thyroxine dose.     

Consequences of exposure to peri-articular injections of micro- and nano-particulate cobalt–chromium alloy

Metal hip replacements generate both metal particles and ions. The biological effects of peri-articular exposure to nanometre and micron sized cobalt chrome (CoCr) wear particles were investigated in a mouse model. Mice received injections of two clinically relevant doses of nanoparticles (32 nm), one of micron sized (2.9 μm) CoCr particles or vehicle alone into the right knee joint at 0, 6, 12 and 18 weeks. Mice were analysed for genotoxic and immunological effects 1, 4 and 40 weeks post exposure. Nanoparticles but not micron particles progressively corroded at the injection site. Micron sized particles were physically removed. No increase of Co or Cr was seen in peripheral blood between 1 and 40 weeks post exposure to particles. No significant inflammatory changes were observed in the knee tissues including ALVAL or necrosis. DNA damage was increased in bone marrow at one and forty weeks and in cells isolated from frontal cortex at 40 weeks after injection with nanoparticles. Mice exposed to the micron sized, but not nanoparticles became immunologically sensitized to Cr(III), Cr (VI) and Ni(II) over the 40 week period as determined by lymphocyte transformation and ELISpot (IFN-γ and IL-2) assays. The data indicated that the response to the micron sized particles was Th1 driven, indicative of type IV hypersensitivity. This study adds to understanding of the potential adverse biological reactions to metal wear products.     

Core Motivations of Childhood Obsessive-Compulsive Disorder: The Role of Harm Avoidance and Incompleteness

Child Psychiatry & Human Development - In an effort to improve patient conceptualization and targeted treatment, researchers have sought to accurately classify OCD subtypes. To date, the most...     

Mortality in intensive care patients with respiratory disease. Is age important?

BACKGROUND--Age has been proposed as a criterion for health care rationing. However, the relationship of age and other prognostic factors to in-hospital mortality in older patients is unclear. The purpose of this study was to examine the effect of age on hospital mortality for patients admitted to the intensive care unit. METHODS--This historical prospective study examined 3050 admissions of patients aged 50 years and older with disease of the lower respiratory tract to intensive care units in 78 hospitals in the United States during an 18-month period (July 1987 through December 1988). The association of age with hospital mortality was examined by means of a multiple logistic regression model that included age, gender, primary discharge diagnosis, severity, and comorbid diseases. RESULTS--Variables significantly predictive of in-hospital mortality included age, severity of illness, diagnosis, and a history of chronic obstructive pulmonary disease. In contrast, gender, diabetes mellitus, congestive heart failure, angina, and stroke/transient ischemic attack were not significant predictors of mortality. Predicted mortalities varied from 0.7% to 40.7% in 50-year-old patients and from 5.5% to 78.6% in 90-year-old patients. CONCLUSIONS--Chronological age is independently associated with in-hospital mortality in patients with disease of the lower respiratory tract admitted to an intensive care unit. However, the clinical importance of this relationship is modulated by other variables, such as the primary diagnosis, the presence of comorbid conditions (chronic obstructive pulmonary disease), and the severity of the acute illness, such that use of age alone is not sufficient to predict hospital outcome.