Given an abstract of a paper, generate a title for this paper such that conveys the key focus of the paper.

Q: Abstract: We compared the MCR, volume of distribution, and rapid phase (rt1/2) and slow phase half-lives of purified pituitary rat (r) TSH, TSH from crude pituitary extracts of normal and hypothyroid rats, TSH from hypothyroid rat sera, and TSH secreted from hypothyroid rat pituitaries incubated in vitro. For 3 h after iv bolus injection into euthyroid rats, 125I-labeled rTSH was determined by acid precipitation in serum and various organs, and unlabeled TSH was measured by RIA. The MCR of TSH from normal pituitary extracts (0.53 +/- 0.02 ml/min) was similar to that of unlabeled purified rTSH (0.52 +/- 0.03), while those from hypothyroid pituitary extracts (0.32 +/- 0.03) and hypothyroid sera (0.33 +/- 0.01) were decreased. The reduced MCR of TSH from hypothyroid pituitaries was due to a decreased distribution volume (8.4 +/- 0.6 ml) compared to that from normal pituitaries (11.4 +/- 0.7) and hypothyroid sera (10.9 +/- 0.8). The decreased MCR of circulating TSH from hypothyroid sera reflected an increase in its rt1/2 (12.6 +/- 0.5 min) vs. that from both normal (5.1 +/- 0.5) and hypothyroid (5.7 +/- 0.4) pituitaries. The rt1/2 of secreted TSH from incubated hypothyroid rat pituitaries (8.5 +/- 0.9) was intermediate between those of circulating and pituitary forms of hypothyroid rTSH. The clearances of intact bovine TSH (bTSH) and deglycosylated bTSH (dg-bTSH) were compared. The dg-bTSH MCR was found to be increased (0.71 +/- 0.02 ml/min) compared to that of bTSH (0.59 +/- 0.02), primarily due to a decreased rt1/2 for dg-bTSH (3.8 +/- 0.1 min) vs. bTSH (4.7 +/- 0.2). Uptake of purified [125I]rTSH was highest in the kidney at all times, varying from 43% of the injected dose at 5 min to 54% at 180 min. We conclude that in the euthyroid rat, 1) the metabolic clearance of TSH differs between pituitary and serum forms and appears to depend on specific molecular features that vary with the physiological state of the animal from which the TSH is derived; 2) since chemical deglycosylation increased the clearance of TSH, we speculate that the chemical basis for changes in TSH clearance may be related to alterations in its carbohydrate structure; and 3) for normal pituitary TSH, the kidney is the major organ of clearance.

A: Differences in the metabolic clearance of pituitary and serum thyrotropin (TSH) derived from euthyroid and hypothyroid rats: effects of chemical deglycosylation of pituitary TSH.
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Q: Abstract: Cell cultures of human keratinocytes contain membrane-associated thioredoxin reductase that is extremely active in reducing radicals on the outer plasma membrane. This enzyme activity was confirmed by its purification from cultures of stratified human keratinocytes by affinity column chromatography. The enzyme was assayed both in vivo and in vitro using a spin-labeled quaternary ammonium compound as the substrate, under saturating conditions in free radical substrate. Specific activities were determined by monitoring the sequential decrease in the amplitude of the electron spin resonance signal per unit of cell protein. The following properties were found: Cultures of adult stratified cells have approximately twice the thioredoxin reductase activity of neonatal cells. The enzyme is inhibited by thioprotein inhibitors (i.e., parachloromecuribenzoate and dinitrochlorobenzene). The activity is regulated by calcium concentrations of the cell culture medium. Stratified keratinocytes are half as active in medium containing 2 mM Ca++ compared with 0.1 mM Ca++ concentration. Product inhibition of the enzyme occurs with oxidized coenzyme NADP+ (i.e., 87% inhibition of enzyme activity over 30 min). The enzyme is heat stable at temperatures of 70 degrees C for 10 min. It is inactivated at 75 degrees C. A comparative study of thioredoxin reductase activity on stratified differentiated and undifferentiated rapidly growing cells was performed. Also, enzyme activity was quantitated for cultured keratinocytes isolated from vitiliginous and normal skin of the same donor. The results of this study, and the connection between this enzyme activity and UV-generated free radicals are reconciled in terms of the mechanism of action and metabolic activity of thioredoxin reductase.

A: Free radical reduction by thioredoxin reductase at the surface of normal and vitiliginous human keratinocytes.
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Q: Abstract: Although 111In-labeled leukocytes have been shown to be a useful technique for detecting infection, it has been postulated that antibiotic therapy may reduce the sensitivity of the leukocyte scan. Many patients with suspected bacterial infections are placed on antibiotics before a definite site of infection has been identified. Three hundred twelve leukocyte scans on 271 patients were retrospectively reviewed and classified as positive or negative, and as to whether or not they were being treated with antibiotics at the time the leukocyte scan was performed. The overall sensitivity, considering all 312 studies, was 90%. One hundred sixty-nine patient studies were on patients receiving antibiotics; 143 studies were on patients not on antibiotics. The sensitivity of the leukocyte scan was 88.7% in patients on antibiotic therapy; it was 92.1% in those who were not receiving antibiotics. The differences in sensitivity between the two groups were not significantly different (p less than 0.05). We conclude that antibiotic therapy does not affect the sensitivity of the 111In-labeled leukocyte scan.

A:
Effect of antibiotic therapy on the sensitivity of indium-111-labeled leukocyte scans.
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