Citations

Autonomous robotic-assisted surgery (RAS) has emerged as a promising objective in biomedical technology, further enhanced by miniaturization toward microrobotic-assisted surgery (μ-RAS). This reduction in scale promises minimally invasive, partially or fully automated surgical procedures, with the potential to reduce patient recovery times, lower medical costs, and enable previously unavailable procedural options. This perspective highlights the specific advances in RAS that potentially map to the microscale (μ-RAS), organized across five surgical domains: endovascular, endoluminal, laparoscopic, ophthalmic, and orthopedic. We examine both clinical demands and technological advances in surgical robotics and identify the key innovations required for progress across these surgical fields. Our contribution is distinct in combining the perspectives of both surgical experts and bioengineering innovators, outlining a roadmap for the advancement and eventual integration of autonomous RAS and μ-RAS into mainstream surgical practice.

The multiple classes of binding sites for the progesterone-receptor complex in hen oviduct muclei were found to be of chromatin origin. The highest-affinity, and presumably most physiologically important class, is localized in oviduct chromatin and contains approx. 6000-10000 sites per nucleus. None of these sites is detected in spleen chromatin. Two new techniques were used for assaying rapidly the binding of steroid-receptor complexes to soluble deoxyribonucleoproteins in vito. The extent of high-affinity binding by the nucleo-acidic protein fraction from spleen chromatin is as great as that by the nucleo-acidic protein from oviduct chromatin. Consequently the tissue-specific nuclear binding of the progesterone receptor is found not to be a consequence of the absence of the nuclear binding sites (acceptors) from chromatin of non-target tissue (spleen), but rather a result of complete masking of these sites. In the target-tissue (oviduct) chromatin, approx. 70% of the high-affinity acceptor sites are also masked. Acidic proteins, and not histones, appear to be responsible for the masking of these acceptor sites. In addition, acidic proteins represent (or at least are an essential part of) these high-affinity sites in the oviduct nucleus. Pure DNA displays a few high-and many low-affinity binding sites. In support of previous work with immature chicks, the acidic protein fraction of the nucleo-acidic results thus support the hypotheis that protein complexed with DNA, and not DNA alone, represent the high-affinity binding sites for the steroid-receptor complexes in nuclear chromatin. The lower-affinity classes of binding sites may represent DNA and/or other nuclear components.

Steroid hormones, including progesterone, are known to bind with high affinity (Kd approximately 1 × 10(-10)M) to receptor proteins once they enter target cells. This complex (the progesterone-receptor) then undergoes a temperature-and/or salt-dependent activation which allows it to migrate to the cell nucleus and to bind to the deoxyribonucleoproteins. The present studies demonstrate that binding the hormone-receptor complex in vitro to isolated nuclei from the oviducts of laying hens required the same conditions as do other studies of bbinding in vitro reported previously, e.g. the hormone must be complexed to intact and activated receptor. The assay of the nuclear binding by using multiple concentrations of progesterone receptor reveals the presence of more than one class of binding site in the oviduct nuclei. The affinity of each of these classes of binding sites range from Kd approximately 1×10(-9)-1×10(-8)M. Assays using free steroid (not complexed with receptor) show no binding to these sites. The binding to each of the classes of sites, displays a differential stability to increasing ionic concentrations, suggesting primarily an ionic-type interaction for all classes. Only the highest-affinity class of binding site is capable of binding progesterone receptor under physioligical-saline conditions. This class represent 6000-10000 sites per cell nucleus and resembles the sites detected in vivo (Spelsberg, 1976, Biochem. J. 156, 391-398) which cause maximal transcriptional response when saturated with the progesterone receptor. The multiple binding sites for the progesterone receptor either are not present or are found in limited numbers in the nuclei of non-target organs. Differences in extent of binding to the nuclear material between a target tissue (oviduct) and other tissues (spleen or erythrocyte) are markedly dependent on the ionic conditions, and are probably due to binding to different classes of sites in the nuclei.

Data are presented to explain discrepancies in the literature involving the in vitro binding of steroid receptor complexes to isolated nuclei and chromatin. The type of binding in vitro of the progesterone-receptor complex to nuclei, chromatin, or DNA of hen organs is largely determined by the ionic strength of the medium. Low ionic conditions (0.01 to 0.05 molar potassium chloride) result in a nonspecific, nonsaturable binding, while high ionic conditions (0.15 to 0.20 molar potassium chloride) create a tissue-specific, saturable binding. Pure DNA binds the steroid receptor complex extensively in low salt but very little in the higher salt conditions.