Volumetric object modeling for surgical simulation

Surgical simulation has many applications in medical education, surgical training, surgical planning and intra-operative assistance. However, extending current surface-based computer graphics methods to model phenomena such as the deformation, cutting, tearing or repairing of soft tissues poses significant challenges for real-time interactions. This paper discusses the use of volumetric methods for modeling complex anatomy and tissue interactions. New techniques are introduced that use volumetric methods for modeling soft-tissue deformation and tissue cutting at interactive rates. An initial prototype for simulating arthroscopic knee surgery is described which uses volumetric models of the knee derived from 3-D magnetic resonance imaging, visual feedback via real-time volume and polygon rendering, and haptic feedback provided by a force-feedback device.     

A Novel Peptide-Grafted Liposomal Delivery System Targeted to Macrophages

The interaction of chemotactic peptide (e.g., fMet-Leu-Phe)-grafted liposomes with macrophages is noted to be rapid and specific. At a grafted peptide concentration of 100 nmol, internalization of the peptide-grafted liposomes by the macrophages is found to reach equilibrium in 30 min. The peptide alone and the peptide-grafted empty liposomes are found to show moderate antileishmanial activity in vitro. Primaquine, which is known to generate O₂⁻ in phagocytic cells, showed leishmanicidal properties when it was tested in vitro against parasite-infected macrophages over a certain range of concentrations. It showed much better efficacy against experimental leishmaniasis when it was used in the fMet-Leu-Phe-grafted liposomal form in comparison with its efficacy when it was either in the free form or encapsulated in ungrafted liposomes. The conventional toxicity parameters (e.g., blood pathology and tissue histology-specific enzyme levels related to normal liver function) are found to be very close to normal when fMet-Leu-Phe-grafted liposomal primaquine is used. The biodegradabilities of both the drug and the delivery systems are also found to be very satisfactory. Thus, this delivery system may have possible applications for the treatment of leishmaniasis as well as other macrophage-associated disorders.     

The role of Tenonplasty in the management of limbal and scleral ischemia due to acute ocular chemical burns

Of the various manifestations of ocular chemical burns (OCBs), ischemia of the limbus and the peri-limbal sclera indicates poor prognosis and in severe cases threaten the integrity of the globe. Tenonplasty is a surgical procedure which involves advancing the Tenon’s capsule over the ischemic areas to provide a vascular supply and to enable migration of the conjunctival epithelium. This review aims to provide an overview of the diagnosis of limbal ischemia and its management with Tenonplasty. A literature review was conducted using the keywords “Tenonplasty,” “Tenon’s capsule,” “ocular chemical injury,” “ocular thermal injury,” “Tenon advancement,” “scleral ischemia,” and “limbal ischemia,” and outcomes were studied from seven selected articles. In addition to clinical evaluation, in vivo imaging techniques such as anterior segment optical coherence tomography angiography can provide an objective method of measuring and monitoring the ischemia and re-perfusion of the peri-limbal vasculature. Tenonplasty can be performed in eyes with acute OCBs with scleral or limbal ischemia by dissecting the Tenon’s layer from the orbit and securing it to the limbus. The indications, mechanism of action, peri-operative considerations, surgical technique, and post-operative care of Tenonplasty are discussed in detail. The average time for post-operative re-epithelization ranges from 1 to 6 months with the formation of a symblepharon being the most common complication. In conclusion, Tenonplasty is a globe-salvaging procedure in cases with severe limbal and scleral ischemia because of OCBs and has good anatomical outcomes priming the globe for subsequent re-constructive and vision-restoring surgeries.     

Co-administration of C-Phycocyanin ameliorates thioacetamide-induced hepatic encephalopathy in Wistar rats

Fulminant hepatic failure (FHF) is a condition with a sudden onset of necrosis followed by degeneration of hepatocytes, without any previously established liver disease, generally occurring within hours or days. FHF is associated with a wide spectrum of neuropsychiatric alterations ranging from stupor to coma, culminating in death. In the present study FHF was induced in rats by the administration of thioacetamide (TAA). Oxidative stress is thought to play a prominent role in the pathophysiology of cerebral changes during FHF leading to the assumption that antioxidants might offer protection. Hence, in the present study the protective effect of C-Phycocyanin (C-PC), a natural antioxidant, was evaluated on TAA-induced tissue damage. C-Phycocyanin was administered intraperitoneally twice at 24 h interval (50 mg/kg body weight) along with the hepatotoxin TAA (300 mg/kg body weight). The animals were sacrificed 18 h after the second injection of TAA treatment and various biochemical parameters were analysed in liver, serum and brain tissues. These studies revealed significant prevention of TAA-induced liver damage by C-PC, as evidenced by a) increase in survival rate; b) the prevention of leakage of liver enzymes (AAT and AST) and ammonia into serum; c) increase in prothrombin time and d) liver histopathology. Ultrastructural studies of astrocytes of different regions of brain clearly showed a decrease in edema after C-PC treatment. TAA-induced histopathological lesions in different regions of the brain namely cerebral cortex, cerebellum and pons medulla were significantly reduced by the co-administration of C-PC with TAA. Further C-PC treatment resulted in a) decrease in the levels of tryptophan and markers of lipid peroxidation and b) elevation in the activity levels of catalase, glutathione peroxidase in different regions of brain. These studies reveal the potential of C-PC in ameliorating TAA-induced hepatic encephalopathy by improving antioxidant defenses.     

Effects of retroviral envelope-protein cleavage upon trafficking, incorporation, and membrane fusion

Retroviral envelope glycoproteins undergo proteolytic processing by cellular subtilisin-like proprotein convertases at a polybasic amino-acid site in order to produce the two functional subunits, SU and TM. Most previous studies have indicated that envelope-protein cleavage is required for rendering the protein competent for promoting membrane fusion and for virus infectivity. We have investigated the role of proteolytic processing of the Moloney murine leukemia virus envelope-protein through site-directed mutagenesis of the residues near the SU-TM cleavage site and have established that uncleaved glycoprotein is unable either to be incorporated into virus particles efficiently or to induce membrane fusion. Additionally, the results suggest that cleavage of the envelope protein plays an important role in intracellular trafficking of protein via the cellular secretory pathway. Based on our results it was concluded that a positively charged residue located at either P2 or P4 along with the arginine at P1 is essential for cleavage.     

“Comparative study of medical abortion by mifepristone with vaginal misoprostol in women < 49 days versus 50–63 days of amenorrhoea”

Objectives

To compare the outcome with Mifepristone and vaginal Misoprostol combination in women having amenorrhea <-49 days (group-A) verses 50–63 days. (Group-B)

Methods

We administered 200 mg of mifepristone to 200 women willing for medical abortion within 63 days of amenorrhea. After 48 hours they were assigned to receive 400 microgram of misoprostol vaginally. At the end of 4 hours, if required, reinstillation of 400 microgram misoprostol vaginally was done.

Results

Complete abortion rate in women with amenorrhea <-49 days verses 50–63 days were 99.16% and 98.75% respectively. Average duration of bleeding was 6.26 (S, D. 2.43 days ) and 6.98 days (2.26 days)respectively and the difference is statistically significant (p<0.05). The proportion of women with induction abortion interval <-4 hours in the two groups as 83.33% and 72.25% respectively. This difference is statistically not significant (Chi-square=3.47, P>0.05). The success rate at the end of 14 days in group A and B was 99.16% and 98.75% respectively and this difference is statistically not significant. (Chi-square = 0.19, P>0.05)

Conclusions

The combination of oral mifepristone and vaginal misoprostol is currently approved for medical abortion in women with amenorrhoea up to 49 days (7 weeks gestation ). Our study has demonstrated that the use of this combination can be effectively and safely extended for inducing abortions in women with amenorrhoea up to 63 days (9 weeks gestation).     

Increased expression of interleukin-1 beta is associated with persistence of the disease and invasion in complete hydatidiform moles (CHM)

Complete hydatidiform moles (CHM), a post-conceptual pathologic condition of the placenta, have a high prevalence rate (12/1,000 deliveries) in Kerala, India. This study addresses the expression of IL-1 alpha and beta by immunohistochemistry in relation to persistence and invasion of the disease. Mild to moderate expression of IL-1 alpha in the villous cytotrophoblasts, syncytiotrophoblasts and decidua of the first trimester in the normal placenta and all gestational ages in the molar placenta were observed. IL-1 beta expression was observed in the extravillous trophoblasts, syncytiotrophoblasts and decidua in both the normal and molar placentae and also in the villous cytotrophoblasts and the stromal Haufbaur cells in molar placentae. Strong expression of IL-1 beta in the placenta suggests its involvement in placental physiology supporting earlier reports. Higher expression of IL-1 beta correlated well with the invasive and persistent nature of the tumour and holds potential as a marker of persistence and invasion in CHM.     

Multiple measures of anesthesia workload during teaching and nonteaching cases

In this study, we sought to examine several measures of anesthesia provider workload during different phases of anesthesia care and during teaching and nonteaching cases. Clinical work was assessed in real-time during 24 general anesthetics performed by consenting anesthesia providers. Workload was measured using physiological (provider heart rate), psychological (self-assessment and observer rating), and procedural (response latency to an alarm light and workload density) techniques. Clinicians' heart rates, observer and self-reported workload scores, and nonteaching workload density were consistently increased during anesthetic induction and emergence compared with maintenance. In nonteaching cases, workload density correlated with heart rate and with psychological workload. Workload density during teaching cases did not decrease during the induction and was significantly greater than during nonteaching cases. Alarm-light response latency (a measure of clinical vigilance) was significantly prolonged during the teaching compared with nonteaching cases. These results suggest that intraoperative teaching increases the workload of the clinician instructor and may reduce vigilance during anesthesia care. Additionally, multiple workload measures may provide a more comprehensive profile of the work demands of clinical cases. IMPLICATIONS: Psychological, physiological, and procedural workload measures during routine general anesthesia cases documented the increased work demands of induction and emergence. Intraoperative teaching increased workload and decreased vigilance, suggesting the need for caution when educating during patient care.