Updated COVID-19 clearance time among patients with cancer in the Delta and Omicron waves.

BACKGROUND: COVID-19 infection delays therapy and in-person evaluation for oncology patients, but clinic clearance criteria are not clearly defined. METHODS: We conducted a retrospective review of oncology patients with COVID-19 at a tertiary care center during the Delta and Omicron waves and compared clearance strategies. RESULTS: Median clearance by two consecutive negative tests was 32.0 days (Interquartile Range [IQR] 22.0-42.5, n = 153) and was prolonged in hematologic malignancy versus solid tumors (35.0 days for hematologic malignancy, 27.5 days for solid tumors, p = 0.01) and in patients receiving B-cell depletion versus other therapies. Median clearance by single negative test was reduced to 23.0 days (IQR 16.0-33.0), with recurrent positive rate 25.4% in hematologic malignancy versus 10.6% in solid tumors (p = 0.02). Clearance by a predefined waiting period required 41 days until an 80% negative rate. CONCLUSIONS: COVID-19 clearance remains prolonged in oncology patients. Single-negative test clearance can balance delays in care with risk of infection in patients with solid tumors.

Cholinergic modulation of trace conditioning trained in serial compound: A developmental analysis.

In four experiments the effects of serial compound conditioning on responding to a trace-conditioned CS were evaluated using a fear conditioning paradigm. The subjects were 18- and 25-day-old Sprague-Dawley rats, previously shown to exhibit little or no trace fear conditioning. Here, animals as young as 18 days of age were shown to be capable of trace conditioning between a visual CS1 and a shock US, provided the trace interval was filled with a non-target CS2 during serial conditioning trials (CS1-->CS2-->US). To explore cholinergic mechanisms involved in trace and serial conditioning, additional experiments assessed conditioned responding following pre-training administration of the muscarinic receptor antagonist scopolamine. Scopolamine produced a dose-dependent reduction in responding to the trace CS1, regardless of whether subjects were trained with standard trace (CS1-->trace interval-->US) or serial (CS1-->CS2-->US) trials. Responding to CS2 was unaffected by scopolamine. These data suggest that central cholinergic systems are functional in the young animals, but are not normally sufficiently activated by standard trace conditioning procedures. The results suggest that serial compound conditioning can promote trace conditioning in young rats, as it does in adults, perhaps by enhancing cholinergic activity during training. Implications for the late ontogenetic emergence of trace conditioning as it relates to maturation of neural pathways and their role in the potentiating effects of a gap filler are discussed.