It is difficult to achieve controlled cutting of elastic, mechanically fragile, and rapidly resealing mammalian cell membranes. Here, we report a photothermal nanoblade that utilizes a metallic nanostructure to harvest short laser pulse energy and convert it into a highly localized explosive vapor bubble, which rapidly punctures a lightly-contacting cell membrane via high-speed fluidic flows and induced transient shear stress. The cavitation bubble pattern is controlled by the metallic structure configuration and laser pulse duration and energy. Integrating the metallic nanostructure with a micropipette, the nanoblade generates a micron-sized membrane access port for delivering highly concentrated cargo (5×108 live bacteria/ml) with high efficiency (46%) and cell viability (>90%) into mammalian cells. Additional biologic and inanimate cargo over 3-orders of magnitude in size including DNA, RNA, 200 nm polystyrene beads to 2 μm bacteria have also been delivered into multiple mammalian cell types. Overall, the photothermal nanoblade is a new approach for delivering difficult to transfer cargo into mammalian cells.
Background Debate exists surrounding the morphological evolution of the submandibular gland (SMG) with aging, and due to the inconclusive influence of patient demographics, there remains hesitancy to incorporate targeted interventions of the SMG into clinical practice. Objectives To determine whether SMG ptosis, hypertrophy, or both is the primary etiology behind increased submandibular volume as one ages. Methods MRI segmentation was used to calculate the total and inframandibular (IM) volume and height of the SMG. Adult subjects with prior MRIs of the head and neck were used for analysis. Those with pathology or artifact compromising the SMG were excluded. Subjects were divided into four age-defined cohorts, for clinical applicability. Results The study included 129 patients (Females n=65; Male n=64) with a mean age of 52.3 (range 20-85). No significant change in total SMG volume was observed between the reference group and all cohorts. IM-SMG volume of the reference cohort was 5.77 cm 3. All 3 cohorts had a greater IM-SMG volume compared to the reference group. The 45-54 cohort had a mean volume of 6.7 cm 3 (p=.4), the 55-64 cohort, 7.5 cm 3 (p=.01), and the 55-64 cohort, 7.2 cm 3 (p=.01). Male sex and overweight or obese BMI were associated with significantly larger total and IM-SMG volumes. Conclusions The novel finding of a significantly larger IM-SMG volume with no change in total volume provides evidence for SMG ptosis rather than hypertrophy as a significant contributor to age-related submandibular fullness. Given no significant difference in total volume or height with aging emphasizes glandular descent.
Background Recently we have seen an expanding practice of targeting the deeper, subplatysmal structures in the neck. In particular, interventions targeting the “bulky” anterior digastric (AD) muscle have been described with excellent results. However, much remains to be understood about the deep anatomy of the neck and the age-associated changes of the AD. Objectives To examine the relationship between AD volume and age. Methods This retrospective study calculated the AD volume utilizing MRI segmentation in subjects between the ages of 20-92 with prior MRIs. Those with compromised imaging due to pathology or artifact were excluded. Subjects were divided into four age-defined cohorts for clinical applicability. Results This study included 129 patients (male n=64) with a mean age of 52.3. The AD volume of the reference group was 3.2 cm3. A linear decrease in muscle volume was observed with age compared to the reference group: age 45-54 cohort, 2.95 cm3 (p=.3), 55-64 cohort, 2.7 cm3 (p=.05) and >65 cohort, 2.45 cm3 (p<0.001). Male sex (p=.0001) and laterality (p=.003) were associated with significantly larger volumes. Overweight and obese BMI classification was not associated with a significantly different volume than normal or underweight subjects (p=.067). Conclusions Our findings suggest an age-associated reduction in AD volume. Gender and laterality significantly affected volume, while BMI did not. While our results do not support the theory of muscular hypertrophy with aging, they reveal that the perceived bulkiness may be due to changes in the surrounding anatomy affecting the morphology of the AD and subsequent blunting of the cervicomental angle.
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