An experimental study was carried out to investigate the amount of drugs loaded on microneedles. The microneedles were made with poly (lactic acid). Aqueous poly (vinyl alcohol) solutions were prepared as drug solutio...An experimental study was carried out to investigate the amount of drugs loaded on microneedles. The microneedles were made with poly (lactic acid). Aqueous poly (vinyl alcohol) solutions were prepared as drug solutions. Two drug loading approaches, i.e., dropping and dipping, were examined. It was found that capillary number is the only relevant dimensionless group for the two methods. For the dropping approach, dried drugs will spread near the bottom of a microneedle patch provided the surface tension is low. As for the dipping approach, both a single microneedle and an array of nine microneedles were examined. For a single microneedle, high capillary rises before pulling and pulling speed are two key factors to increase the drug loading volume. For an array of microneedles, the effect of capillary rise owing to the interaction between microneedles would increase the drug loading volume several times higher than a single microneedle of the same dimension.展开更多
Although the natural history of recurrence/progression in patients with intraductal papillary mucinous neoplasms (IPMN) of the pancreas has not been studied thoroughly, the three principal mechanisms have been identif...Although the natural history of recurrence/progression in patients with intraductal papillary mucinous neoplasms (IPMN) of the pancreas has not been studied thoroughly, the three principal mechanisms have been identified: (a) presence of residual disease at the transection margin, (b) presence of intraductal/intraparenchymal metastases and (c) development of new primary lesions. Mechanisms (a) and (b) result in metastatic lesions that are genetically related to the primary, while new primary lesions (mechanism c) are genetically distinct. Interestingly, recurrence/progression in IPMN displays conceptual parallels with the well-established paradigm of disease recurrence in patients with hepatocellular carcinoma (HCC). Specifically, patients with HCC may also develop recurrent tumors due to microscopic residual disease/intrahepatic metastasis which are genetically similar to the primary while the development of genetically unrelated, de novo HCC after curative-intent resection is also common. The latter has been attributed to the presence of a widespread genetic abnormality ( "field defect" ) in the liver (ie, cirrhosis). Given the conceptual similarities between IPMN and HCC, a pancreatic "field defect" may also be hypothesized to exist. This review does not suggest that HCC and IPMN have identical pathogeneses, but rather that they have conceptual similarities in tumor recurrence/progression;thus, lessons learned from HCC could be applied to IPMN research and subsequent management. Conceptual similarities in tumor progression and recurrence may also be observed between IPMN and other malignancies. However, HCC was selected because it is well studied and can serve as a paradigm.展开更多
文摘An experimental study was carried out to investigate the amount of drugs loaded on microneedles. The microneedles were made with poly (lactic acid). Aqueous poly (vinyl alcohol) solutions were prepared as drug solutions. Two drug loading approaches, i.e., dropping and dipping, were examined. It was found that capillary number is the only relevant dimensionless group for the two methods. For the dropping approach, dried drugs will spread near the bottom of a microneedle patch provided the surface tension is low. As for the dipping approach, both a single microneedle and an array of nine microneedles were examined. For a single microneedle, high capillary rises before pulling and pulling speed are two key factors to increase the drug loading volume. For an array of microneedles, the effect of capillary rise owing to the interaction between microneedles would increase the drug loading volume several times higher than a single microneedle of the same dimension.
基金This work was financially supported by the NIH/NCI Cancer Center Support(No. P30 CA008748)
文摘Although the natural history of recurrence/progression in patients with intraductal papillary mucinous neoplasms (IPMN) of the pancreas has not been studied thoroughly, the three principal mechanisms have been identified: (a) presence of residual disease at the transection margin, (b) presence of intraductal/intraparenchymal metastases and (c) development of new primary lesions. Mechanisms (a) and (b) result in metastatic lesions that are genetically related to the primary, while new primary lesions (mechanism c) are genetically distinct. Interestingly, recurrence/progression in IPMN displays conceptual parallels with the well-established paradigm of disease recurrence in patients with hepatocellular carcinoma (HCC). Specifically, patients with HCC may also develop recurrent tumors due to microscopic residual disease/intrahepatic metastasis which are genetically similar to the primary while the development of genetically unrelated, de novo HCC after curative-intent resection is also common. The latter has been attributed to the presence of a widespread genetic abnormality ( "field defect" ) in the liver (ie, cirrhosis). Given the conceptual similarities between IPMN and HCC, a pancreatic "field defect" may also be hypothesized to exist. This review does not suggest that HCC and IPMN have identical pathogeneses, but rather that they have conceptual similarities in tumor recurrence/progression;thus, lessons learned from HCC could be applied to IPMN research and subsequent management. Conceptual similarities in tumor progression and recurrence may also be observed between IPMN and other malignancies. However, HCC was selected because it is well studied and can serve as a paradigm.
