Opioid growth factor modulates angiogenesis

AbstractObjective: Induced angiogenesis has recently been attempted as a therapeutic modality in patients with occlusive arterial atherosclerotic disease. We investigated the possible role of endogenous opioids in the modulation of angiogenesis. Methods: Chick chorioallantoic membrane was used as an in vivo model to study angiogenesis. Fertilized chick eggs were incubated for 3 days, explanted, and incubated for an additional 2 days. Three-millimeter methylcellulose disks were placed on the surface of the chorioallantoic membrane; each disk contained opioid growth factor ([Met5]-enkephalin; 5 μg), the short-acting opioid receptor antagonist naloxone (5 μg), opioid growth factor and naloxone together (5 μg of each), the long-acting opioid antagonist naltrexone (5 μg), or distilled water (control). A second series of experiments was performed with distilled water, the angiogenic inhibitor retinoic acid (1 μg), and vascular endothelial growth factor (1 μg) to further evaluate our model. The developing vasculature was imaged 2 days later with a digital camera and exported to a computer for image analysis. Total number of blood vessels, total vessel length, and mean vessel length were measured within a 100-mm2 region surrounding each applied disk. Immunocytochemical analysis was performed with antibodies directed against opioid growth factor and its receptor (OGFr). Results: Opioid growth factor had a significant inhibitory effect on angiogenesis, both the number of blood vessels and the total vessel length being decreased (by 35% and 20%, respectively) in comparison with control levels (P <.005). The simultaneous addition of naloxone and opioid growth factor had no effect on blood vessel growth, nor did naloxone alone. Chorioallantoic membranes exposed to naltrexone displayed increases of 51% and 24% in blood vessel number and length, respectively, in comparison with control specimens (P <.005). These results indicate that the opioid growth factor effects are receptor mediated and tonically active. Immunocytochemistry demonstrated the presence of both opioid growth factor and OGFr within the endothelial cells and mesenchymal cells of the developing chorioallantoic membrane vessel wall. Retinoic acid significantly reduced the number and the total length of blood vessels, whereas vascular endothelial growth factor increased both the number and the length of blood vessels in comparison with the controls (P <.0001). The magnitude of opioid growth factor's effects were comparable to those seen with retinoic acid, whereas inhibition of opioid growth factor with naltrexone induced an increase in total vessel length comparable to that for vascular endothelial growth factor. Conclusions: These results demonstrate for the first time that endogenous opioids modulate in vivo angiogenesis. Opioid growth factor is a tonically active peptide that has a receptor-mediated action in regulating angiogenesis in developing endothelial and mesenchymal vascular cells. (J Vasc Surg 2000;32:364-73.

A national survey of practice patterns in the noninvasive diagnosis of deep venous thrombosis

AbstractPurpose: Recent studies have recommended unilateral venous duplex scanning for the diagnosis of deep venous thrombosis (DVT) in patients who are unilaterally symptomatic. Vascular laboratory accreditation standards, however, imply that bilateral leg scanning should be performed. We examined whether actual practice patterns have evolved toward limited unilateral scanning in such patients. Methods: A questionnaire was mailed to all 808 vascular laboratories in the United States that were accredited by the Intersocietal Commission for the Accreditation of Vascular Laboratories (ICAVL). To encourage candid responses, the questionnaires were numerically coded and confidentiality was assured. Results: A total of 608 questionnaires (75%) were completed and returned. Most of the respondents (442; 73%) were either community-hospital or office-based laboratories, and the remaining 163 (27%) were university or affiliated-hospital laboratories. Most of the laboratories (460; 76%) had been in existence for 9 years or more, and 65% had been ICAVL–accredited in venous studies for 3 years or more. Board-certified vascular surgeons were the medical directors in 54% of the laboratories. Duplex ultrasound scanning was the diagnostic method used by 98% of the laboratories. In patients with unilateral symptoms, 75% of the laboratories did not routinely scan both legs for DVT. A large majority (75%) believe that bilateral scanning is not clinically indicated. Only 57 laboratories (14%) recalled having patients return with a DVT in the previously unscanned leg, with 93% of these laboratories reporting between one and five such patients. This observation correlated with larger volumes of venous studies performed by those laboratories (P < .05). Similarly, only 52 laboratories (12%) recalled having patients return with subsequent pulmonary emboli. Of these laboratories, only five reported proximal DVT in the previously unscanned legs of such patients. Of all these laboratories, therefore, only 1% (5 of 443) have potentially missed the diagnosis of a DVT that caused a preventable pulmonary embolus with such a policy. Among those laboratories that always perform bilateral examinations, 41% do so because of habit. Most (61%) of the laboratories that perform bilateral scanning would do unilateral scanning if it were specifically approved by ICAVL. Conclusion: Three quarters of the ICAVL–accredited vascular laboratories perform limited single-extremity scanning for the diagnosis of DVT in patients with unilateral symptoms. This broad clinical experience suggests that this practice is widespread in selected patients. Clinical protocols should be established to provide guidelines for local laboratory implementation. (J Vasc Surg 1999;29:799-806.

The educational value of an audience response system use in an Iraqi medical school

BACKGROUND: Medical education is continually evolving particularly through the modern implementation of educational technology. Enhancing interactive learning in the classroom or lecture settings is one of the growing uses of educational technology. The role and potential benefits of such technology may not be as evident in developing educational systems like the one in Iraq. The purpose of this study was to examine the effect and perception of the use of an audience response system (ARS) on interactive medical education in Iraq. A mixed quantitative and qualitative research methodology approach was used to study the effects and users’ perceptions (both student and tutor) of the ARS. METHOD: The study was conducted in an Iraqi medical school in the Head and Neck course during the spring semester for third-year medical students. The course involved fifteen one-hour lectures over fifteen weeks. Users’ perceptions were evaluated by survey and focus group discussions (FGD). Descriptive statistics were used for quantitative measures and thematic analysis for the qualitative data. An ARS system was installed and integrated into the course lectures throughout the course period of three months to enhance interactive learning. Three to five interactive questions were used in each lecture. Anonymous participation and answers were maintained. The appropriate discussion was initiated when pertinent depending on students’ answers. RESULT: Most students (77% of survey, 85% of FGD) perceived the use of ARS as impactful on their learning. They found the ARS engaging (70%), motivating (76%), promoting interactions (73%), and augment learning through better understanding and remembering (81%). Through the FGD, students expressed improved focus, enhanced thinking and reflection, and joyful learning. The educator perceived the ARS use as practical, interactive, thinking-stimulator, and reflective of student’s understanding. The required technology skills were reasonable; however, it demanded extra non-insignificant time to learn the use. CONCLUSION: The perception of the ARS in this study was overall positive, providing encouragement for wide application of this technology in medical education in the developing world. Further studies are needed to validate and prioritize ARS usage in medical education in Iraq. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12909-022-03381-z

Quantitative measurement of pitting edema with a novel edema ruler

Lower extremity edema is a symptom of chronic venous disease and venous insufficiency. However, clinical evaluations rely on the qualitative evaluation of the pitting depth, which is neither well-defined nor quantitative. We created a novel three-dimensionally printed edema ruler as a quantitative method to measure pitting depth. Twenty-five patients (50 legs) with chronic venous disease were evaluated for ankle edema using the edema ruler. The results demonstrate excellent intraclass correlation for both single (0.944, P < .001) and average (0.971, P < .001) measurements. The edema ruler is a noninvasive, useful, and objective tool for the clinical measurement of lower extremity edema