Pack-Year Smoking History: An Inadequate and Biased Measure to Determine Lung Cancer Screening Eligibility

PURPOSE

Pack-year smoking history is an imperfect and biased measure of cumulative tobacco exposure. The use of pack-year smoking history to determine lung cancer screening eligibility in the current US Preventive Services Task Force (USPSTF) guideline may unintentionally exclude many high-risk individuals, especially those from racial and ethnic minority groups. It is unclear whether using a smoking duration cutoff instead of a smoking pack-year cutoff would improve the selection of individuals for screening.

METHODS

We analyzed 49,703 individuals with a smoking history from the Southern Community Cohort Study (SCCS) and 22,126 individuals with a smoking history from the Black Women's Health Study (BWHS) to assess eligibility for screening under the USPSTF guideline versus a proposed guideline that replaces the ≥20-pack-year criterion with a ≥20-year smoking duration criterion.

RESULTS

Under the USPSTF guideline, only 57.6% of Black patients with lung cancer in the SCCS would have qualified for screening, whereas a significantly higher percentage of White patients with lung cancer (74.0%) would have qualified (P < .001). Under the proposed guideline, the percentage of Black and White patients with lung cancer who would have qualified for screening increased to 85.3% and 82.0%, respectively, eradicating the disparity in screening eligibility between the groups. In the BWHS, using a 20-year smoking duration cutoff instead of a 20-pack-year cutoff increased the percentage of Black women with lung cancer who would have qualified for screening from 42.5% to 63.8%.

CONCLUSION

Use of a 20-year smoking duration cutoff instead of a 20-pack-year cutoff greatly increases the proportion of patients with lung cancer who would qualify for screening and eliminates the racial disparity in screening eligibility between Black versus White individuals; smoking duration has the added benefit of being easier to calculate and being a more precise assessment of smoking exposure compared with pack-year smoking history.

Short communication: Influence of intramuscular injection of vitamin B12 in early-lactation dairy cows on Mozzarella cheese quality and vitamin B12 stability

The current study explored the effect of intramuscular injection of vitamin B₁₂ (VB₁₂) in early-lactation dairy cows on subsequent low-moisture part-skim Mozzarella cheese quality and VB₁₂ levels during cheese processing and storage. Twenty-four peripartum dairy cows were blocked based on parity and milk yield and randomly assigned into 2 treatments: basal diet (CON) and basal diet with an intramuscular injection of 10 mg of VB₁₂ per cow per week (VB₁₂). Raw milk was collected to determine VB₁₂ content and then used to make low-moisture part-skim Mozzarella cheese 8 wk after injection. The VB₁₂ content of raw milk and cheese was determined using ultra-performance liquid chromatography coupled with tandem mass spectrometry. We found that VB₁₂ content was significantly increased in milk (15.43 vs. 3.30 ng/mL) and fresh cheese (3.72 ng/g vs. undetectable) from the VB₁₂ group compared with the CON group. However, approximately 70% of VB₁₂ was lost in the whey during cheese making, and no VB₁₂ was detectable in either cheese treatment after 8 wk of storage. Furthermore, no significant differences were observed in fat and protein contents in the cheese between the 2 groups. For cheese color, the b* value increased and the a* value decreased slightly in fresh VB₁₂ cheese. Functional properties of stretchability, flowability, and meltability of VB₁₂ cheese were initially comparable to that of CON cheese, but higher flowability and meltability was observed in VB₁₂ cheese after 8 wk of storage. In summary, intramuscular injection of VB₁₂ in early-lactation dairy cows increases the content of VB₁₂ in milk and fresh cheese with no adverse effect on cheese quality, but substantial VB₁₂ is lost during cheesemaking and declines rapidly during storage.

A first-principles study on magnetic properties of the intrinsic defects in wurtzite ZnO

Since the origin of magnetism in ZnO-based diluted magnetic semiconductors (DMSs) is still controversial, in this work, we presented a detailed study on the magnetic, structural, and electronic properties of wurtzite ZnO-based DMS systems with point and complex intrinsic defects. Two outer electrons from neutral oxygen vacancy (V_O) occupy the a₁ orbital, making the inducted magnetic moment to be zero, while a cluster including three V_Os leads to a magnetic moment of ∼1 μ_B. The magnetic moment of the system with a Zn vacancy (V_Zn) is 1.65 μ_B. When two neutral V_Zns in different relative distances were created in respective supercells, the systems showed different magnetic moments induced by the unequal level between the highest electron occupied orbital of the defect state introduced by different V_Zn sites and the valence band maximum. The system of a neutral O occupying an octahedral site gives rise to a magnetic moment of 2 μ_B, while zinc interstitial and antisite defects do not cause spin polarization. The system with a complex defect of V_O and V_Zn is magnetic when those vacancies are adjacent but still do not cause the compensation effect. The oxygen interstitial defect is unstable, and V_Zn easily turns into the complex defect. We suggest that V_O clusters and V_Zn complex defects could likely be the origin of ferromagnetism in undoped ZnO.

Different endosperm structures in wheat and corn affected in vitro rumen fermentation and nitrogen utilization of rice straw-based diet

Starchy grain is usually supplemented to diets containing low-quality forage to provide sufficient energy for ruminant animals. Ruminal degradation of grain starch mainly depends on the hydrolysis of the endosperm, which may be variable among grain sources. This study was conducted to investigate the influence of endosperm structure of wheat and corn on in vitro rumen fermentation and nitrogen (N) utilization of rice straw. The 3×4 factorial design included three ratios of concentrate to forage (35:65, 50:50 and 65:35) and four ratios of wheat to corn starch (20:80, 40:60, 60:40 and 80:20). The endosperm structure was detected by scanning electronic microscopy and a confocal laser scanning microscopic. An in vitro gas test was performed to evaluate the rumen fermentation characteristics and N utilization. Starch granules were embedded in the starch-protein matrix in corn, but more granules were separated from the matrix in the wheat endosperm. With the increasing ratio of wheat, rate and extent of gas production, total volatile fatty acids, and ammonia N increased linearly (P<0.01), but microbial protein concentration decreased (quadratic, P<0.01), with the maximum value at a ratio of 40% wheat. The efficiency of N utilization decreased linearly (P<0.01). Rumen fermentation and N utilization were significantly affected by the concentrate-to-forage ratio (P<0.01). Significant interactions between the concentrate-to-forage ratio and the wheat-to-corn ratio were detected in total volatile fatty acids and the efficiency of N utilization (P<0.01). In summary, the starch-protein matrix and starch granules in the wheat and corn endosperm mixture play an important role in the regulation of rumen fermentation and N utilization under low-quality forage.