A Novel method for the identification and quantification of weight faltering.

OBJECTIVE: We describe a new method for identifying and quantifying the magnitude and rate of short-term weight faltering episodes, and assess how (a) these episodes relate to broader growth outcomes, and (b) different data collection intervals influence the quantification of weight faltering. MATERIALS AND METHODS: We apply this method to longitudinal growth data collected every other day across the first year of life in Gambian infants (n = 124, males = 65, females = 59). Weight faltering episodes are identified from velocity peaks and troughs. Rate of weight loss and regain, maximum weight loss, and duration of each episode were calculated. We systematically reduced our dataset to mimic various potential measurement intervals, to assess how these intervals affect the ability to derive information about short-term weight faltering episodes. We fit linear models to test whether metrics associated with growth faltering were associated with growth outcomes at 1 year, and generalized additive mixed models to determine whether different collection intervals influence episode identification and metrics. RESULTS: Three hundred weight faltering episodes from 119 individuals were identified. The number and magnitude of episodes negatively impacted growth outcomes at 1 year. As data collection interval increases, weight faltering episodes are missed and the duration of episodes is overestimated, resulting in the rate of weight loss and regain being underestimated. CONCLUSIONS: This method identifies and quantifies short-term weight faltering episodes, that are in turn negatively associated with growth outcomes. This approach offers a tool for investigators interested in understanding how short-term weight faltering relates to longer-term outcomes.

Migration in the 1930s: Beyond the Dust Bowl.

This paper analyzes in detail the role of environmental and economic shocks in the migration of the 1930s. The 1940 U.S. Census of Population asked every inhabitant where they lived five years earlier, a unique source for understanding migration flows and networks. Earlier research documented migrant origins and destinations, but we will show how short term and annual weather conditions at sending locations in the 1930s explain those flows, and how they operated through agricultural success. Beyond demographic data, we use data about temperature and precipitation, plus data about agricultural production from the agricultural census. The widely known migration literature for the 1930s describes an era of relatively low migration, with much of the migration that did occur outward from the Dust Bowl region and the cotton South. Our work about the complete U.S. will provide a fuller examination of migration in this socially and economically important era.

Exposure levels associated with Na(131)I thyroid cancer patients: correlation with initial activity and clinical physical parameters.

Initial radiation exposure levels X (0) at 1 m from the navel of thyroid cancer patients were measured for 165 individuals at the time of ingestion. Some 61 patients had previously signed informed consent so only those patients could be assayed with regard to body parameters. While the activity was in the stomach, resultant X (0) values were seen to be linearly correlated with the total (131)I activity (A) given orally. Yet large differences in X (0) were seen; e.g., at A = 7.4 GBq, variations of a factor of four were found between the largest and smallest exposure rates. Correlation analyses were performed between normalized rate X (0)A-1 and several patient physical parameters. These included age, sex, height, weight, and BMI (body mass index). Only weight and BMI had significant linear correlation (p < 0.05) with normalized exposure rate. In the former case, the correlation coefficient ρ (weight) was -0.296 (p = 0.02). Using BMI as the independent variable, ρ (BMI) was -0.386 (p = 0.0021). With further analysis of the BMI variation, 95% confidence intervals could be determined at various BMI levels. For example, at 28 kg m(-2), the normalized rate varied between 0.039 and 0.0446 µGy h(-1) MBq(-1)-approximately a ±6.5% variation on the mean value of 0.0419 µGy h(-1) MBq(-1) at this BMI. Given such clinical information, differences in normalized exposure rate can be reduced to values on the order of ±10% or less for BMI values over the clinically relevant interval 20 to 40 kg m(-2).

Modification of a motel-type room to accommodate patients receiving radioiodine therapy: reduction of environmental exposure.

Patients receiving ¹³¹I-based therapies are generally restricted in leaving the medical institution. In the U.S., the U.S. Nuclear Regulatory Commission (U.S. NRC) has developed the rule that a ≤ 7 mR h⁻¹ reading at 1 m from the patient (or 33 mCi) is sufficient to allow unrestricted release. Because of home situations and other constraints, it is preferable that a patient-specific release level be determined by the radiation safety staff. Locally, the City of Hope has instituted a general release criterion of ≤ 2 mR h⁻¹ at 1 m. While contributing to a reduction in public exposure, this as low as reasonably achievable (ALARA) approach is difficult to justify on a cost basis due to the expense of maintaining the radioactive individual in a hospital room. Instead, it was determined that a motel-type room already on the campus be modified to allow the patient to remain on-site until at or below a locally permitted release level. By adding lead to the bathroom area and sealing the tile surfaces, the room may be converted for less than $5,000. Daily cost for the patient is $65. In comparing the use of this facility for thyroid cancer patients from 2006 to 2010, it was found that the public exposure at 1 m was reduced by approximately 70% as compared to release at the 7 mR h level. In addition, controlling the release reduces the likelihood of a radiation incident in the public environment such as on public transportation or in a hotel.

Use of hydrodynamic flow focusing for the generation of biodegradable camptothecin-loaded polymer microspheres.

The present study was conducted to investigate the use of hydrodynamic flow focusing for the generation of biodegradable polymer microspheres encapsulating the anticancer drug camptothecin. Poly(D,L-lactide-co-glycolide) (PLGA) and poly(L-lactide) (PLA) were used as the matrix materials. Camptothecin was dissolved in the disperse phase and microspheres with a mean size between 2 and 3 microm generated using hydrodynamic flow focusing. When up to 1 wt.% of the drug was added to PLA, the drug encapsulation efficiency was 64%. For PLGA, the drug encapsulation efficiency was between 39 and 46%. Drug release from PLA particles was rapid and complete within 6 h, while drug release from PLGA particles showed no burst effect and followed a first order release profile. The encapsulated camptothecin stayed in its active lactone form, as shown by HPLC, and was able to exert cell toxic effects as shown by a cell viability assay. Hydrodynamic flow focusing is a promising tool for the preparation of drug-releasing biodegradable microspheres typically made by solvent evaporation and/or solvent extraction, as indicated by the successful encapsulation of the anticancer drug camptothecin.

Fischer 344 rats display age-related memory deficits in trace fear conditioning.

A functional hippocampus is required for trace fear conditioning, which involves learning the association of a tone and shock that are separated over time. Young and aged rats received 10 trace conditioning trials. Twenty-four hours later, rats were tested for fear to the tone in a novel chamber by measuring freezing. The results showed significantly lower levels of freezing in aged rats as compared with young rats, which provides evidence of age-related memory impairments. Pseudorandom conditioning groups showed low levels of freezing, indicative of no associative memory. Age-related memory deficits were not found with delay conditioning, which suggests no age-related sensory-motor deficits. These data suggest that aging hinders the ability of the hippocampus to process information separated over time.