High speed impact on granular media: breakdown of conventional inertial drag models.

In this study, we extensively explore the impact process on granular media, particularly focusing on situations where the ratio of impact speed to acoustic speed is on the order of 0.01-1. This range significantly exceeds that considered in existing literature (0.0001-0.001). Our investigation involves a comprehensive comparison between our simulation data, obtained under high-speed conditions, and the established macroscopic drag models. In the high-speed regime, conventional drag force models prove inadequate, and the drag force cannot be separated into a depth-dependent static pressure and a depth-independent inertial drag, as suggested in previous literature. A detailed examination of the impact process in the high-speed limit is also presented, involving the spatio-temporal evolution of the force chain network, displacement field, and velocity field at the particle length scale. Unlike prior works demonstrating the exponential decay of pulses, we provide direct evidence of acoustic pulses propagating over long distances, reflecting from boundaries, and interfering with the original pulses. These acoustic pulses, in turn, induce large scale reorganization of the force chain network, and the granular medium continuously traverses different jammed states to support the impact load. Reorientation of the force chains leads to plastic dissipation and the eventual dissipation of the impact energy. Furthermore, we study the scaling of the early stage peak forces with the impact velocity and find that spatial dimensionality strongly influences the scaling.

Surgical management of cystic duct stump calculi causing post-cholecystectomy syndrome: A prospective study.

Aim: Remnant cystic duct stump calculi are an uncommon but important cause of 'post-cholecystectomy syndrome'. High index of suspicion is needed to diagnose this condition in a symptomatic post-cholecystectomy patient. We present our experience with the surgical management of this condition. Patients and Methods: This prospective study included 19 patients with residual gallstone disease who underwent completion cholecystectomy between August 2016 and October 2021. Investigations included abdominal ultrasound and magnetic resonance cholangiopancreatography. The demographic, clinical, surgical and early post-operative variables of these patients were prospectively maintained and analysed. Results: The study included 14 women and 5 men. The mean age was 42.1 years (range, 14-80 years). The median duration between index surgery and completion cholecystectomy was 36 months (range, 2-178 months) (interquartile range, 105 months). The follow-up duration was 2 months. The initial surgery was open cholecystectomy in 17 and laparoscopic cholecystectomy in 2 patients. All patients with residual stump stone presented with pain, while 10 out of 19 patients complained of dyspepsia. Completion cholecystectomy could be performed laparoscopically in 16 cases, whereas 3 patients underwent open surgery. The mean operative time was 80 min (range, 55-140 min), and the mean blood loss was 100 ml (range, 50-160 ml). The mean hospital stay was 3 days (range, 2-10 days). No post-operative mortality or major morbidity was recorded in any of our patients. Conclusion: Laparoscopic excision of the cystic duct stump is feasible and safe even after previous open cholecystectomy. It is increasingly becoming the treatment of choice where expertise is available.

Tactics, techniques, and challenges in the management of giant choledochal cyst in adolescents and adults: a retrospective cohort study.

BACKGROUND: Choledochal cyst is a rare congenital anomaly manifesting as cystic dilatation of the biliary tree. This study presents our 5-year experience with giant choledochal cyst in adolescents and adults, focusing primarily on its clinical presentation, operative challenges, and pragmatic solutions. METHODS: A retrospective observational study was conducted on 58 adolescent and adult choledochal cyst patients who were managed at a tertiary care hospital. Giant choledochal cyst is defined as cyst with a maximum diameter of ≥ 10 cm. Demographic profile, clinical presentation, and surgical outcome of these patients were analyzed. RESULTS: A total of 12 patients with giant choledochal cyst were managed in our department in a duration of 5 years. The median age of patients with giant choledochal cyst was 20 years (range, 13-30 years) and male to female ratio was 1:2. Giant choledochal cysts were more symptomatic and 8 out of 12 presented with classic triad of abdominal pain, mass, and jaundice. One patient with giant choledochal cyst had metastatic cholangiocarcinoma. Eleven patients underwent surgical cyst excision. Surgery of the giant cyst was challenging and required technical modifications for safe excision. CONCLUSION: Giant choledochal cyst is an unusual entity that is rarely encountered beyond first decade of life. These cysts pose unique surgical challenges and require modification of the standard operative technique.

Correlation Between Circulating Cell-Free DNA Levels and Breast Cancer Subtypes: A Prospective Observational Study.

INTRODUCTION: Breast cancer (BC), a heterogeneous disease, is one of the leading causes of cancer-related deaths among women worldwide. Circulating cell-free DNA (cfDNA) levels have been persistently reported to be elevated in BC patients. In the current study, we evaluated the correlation between the cfDNA levels in patients with BC and its subtypes. METHODS: We recruited newly diagnosed, histopathologically confirmed BC patients aged >18 years (N=39), who did not have any previous malignancy, from the Department of Surgical Oncology, Indira Gandhi Institute of Medical Sciences (IGIMS), Patna, Bihar, India. A total of 6 ml of venous blood was collected from each subject; of this, 1 ml was subjected to complete blood count (CBC), and 4 ml was transferred to a clot-activated collection vial for plasma separation and the cfDNA isolation thereof. In addition to the basic demographic history of each patient, the information on the cancer subtype was as also recorded from the medical records of each patient. All the data were analysed by GraphPad Prism Version 8 (Insightful Science, LLC, San Diego, California, United States). One-way ANOVA was used to test the difference between more than two groups. Pearson correlation was also estimated between cfDNA levels and various CBC indices. A two-tailed p-value<0.05 was considered statistically significant. RESULTS: The mean age of included patients was 48.6±8.20 years. The mean levels of cfDNA were 2.81±2.39 ng/µL. The mean counts of various blood cell types and other indices of CBC were in the normal range. Compared to BC patients with estrogen receptors (ER+), the cfDNA levels were significantly higher in patients with human epidermal growth factor receptor 2 (HER2+) and triple-negative BC (TNBC) (p<0.05).  Conclusion: The elevated levels of cfDNA in patients with BC can be a prognostic marker for the disease subtype. However, more replicative studies are warranted to substantiate our findings.

Solid Pseudopapillary Neoplasm of the Pancreas: A Single-Center Experience of a Rare Neoplasm.

BACKGROUND: Solid pseudopapillary neoplasm (SPN) of the pancreas is an extremely rare pancreatic exocrine tumor. The study aims to report our experience with the SPN of the pancreas. METHODS: A retrospective analysis of the prospectively maintained database was carried out of all the cases diagnosed and treated as SPN between January 2019 and January 2023. Patient characteristics including age, gender, clinical presentation, laboratory examinations, imaging features, surgical details, and histopathological and immunohistochemistry details were analyzed. RESULTS: During this period, eight cases were diagnosed with SPN. All patients were female with a median age of 25.75 years (range 14-55 years). All cases presented with pain in the abdomen, and four patients had a mass per abdomen. In all the cases, contrast-enhanced computed tomography (CECT) abdomen was done for the diagnosis and had preoperative suspicion of the pseudopapillary tumor. In four cases, the tumor was located in the head region, while in four cases, the tumor was in the body and tail of the pancreas. The median size of the tumor was 12 cm (range 3.5-15 cm). Three cases underwent Whipple's procedure and one patient was unresectable. Two out of four patients with body and tail tumors underwent distal pancreatectomy with splenectomy, one underwent spleen-preserving distal pancreatectomy, and one patient underwent central pancreatectomy. CONCLUSION: SPN is a rare neoplasm that primarily affects young women. Clinicopathologic and immunohistochemical features are diagnostic. Surgical resection is generally curative with a good long-term outcome.

Geographical pattern of carcinoma gallbladder in Bihar and its association with river Ganges and arsenic levels: Retrospective individual consecutive patient data from Regional Cancer Centre.

BACKGROUND: Indo-Gangetic basin is known to have higher incidence of gallbladder cancer. Proximity to River Ganga and high heavy metal in soil exposure have been postulated as risk factors. AIM: This study aims to evaluate the geographical pattern of gallbladder cancer from consecutive patient database enrolled in hospital-based cancer registry (HBCR). OBJECTIVES: To evaluate demographic profile and districtwise/zonewise dispersion of gallbladder cancer cases registered in HBCR from year 2014 to 2016. To evaluate association of carcinoma gallbladder (CaGB) due to proximity of Ganges, districts of high soil arsenic levels and referral bias. MATERIALS AND METHODS: Demographic profile and district-based location of individual consecutive gallbladder cancer patient registered in Regional Cancer Centre from the year 2014 till 2016 were analyzed. Population data from 2011 census and arsenic soil content data from central groundwater body were obtained. Frequency distribution, cross tabulation, and odds ratio were used to analyze risk of CaGB across population subsets in Bihar. RESULTS: A total of 1291 consecutive patients of CaGB were registered from 2014 to 2016. Median age at diagnosis was 55 years (range 18-95 years). Male to female ratio was 0.6. Patna (16%) followed by Vaishali (5.8%), Sitamarhi (5%), Madhubani (4.7%), Gaya (4%), and Samastipur (4%) had highest cases. Districts along main central River Ganga (n = 12) and those exposed to high arsenic soil content (n = 15) had higher odds ratio for CaGB, 1.72 (95% confidence interval [CI]: 1.54-1.91, P = 0.001), and 1.45 (95% CI: 1.30-1.62, P = 0.001), respectively. Districts within 100 km radius of our institute had higher gallbladder cancer cases, odds ratio 1.81 (95% CI: 1.62-2.03, P = 0.001), suggesting significant referral bias predominantly contributed by cases registered under Patna and Vaishali districts. CONCLUSION: CaGB is major public health problem in Bihar. Exposure to high soil arsenic levels and proximity to River Ganga are strongly associated with gallbladder cancer. Systematic population-based longitudinal studies are needed to explore above hypothesis.

Biliary atresia with aneurysmal dilatation of hepatic artery: A rare anomaly.

INTRODUCTION: The coexistent biliary atresia with aneurysmal dilatation of hepatic artery is a rare association. To know these anomalies will avoid many per operative complications. It is also important to mention that these children require liver transplantation in the long run then these vascular anomalies become more relevant. PRESENTATION OF CASE: A four month old male child presented with features of biliary atresia. On exploration a cystic expansile mass was detected beneath thread like common bile duct. Subsequent aspiration and studies proved it to be aneurysmal dilatation of hepatic artery. DISCUSSION: With biliary atresia many vascular and cardiac malformations have been described but aneurysmal dilatation of hepatic artery is a rare association. These anomalies may have impact on aetiopathogenesis of biliary atresia and also future liver transplantation. CONCLUSION: Awareness of rare association of hepatic artery aneurysm with biliary atresia will help in understanding aetiopathogenesis of biliary atresia and planning liver transplantation in such cases.

Gossypiboma mimicking posterior urethral stricture.

INTRODUCTION: Foreign bodies in the urogenital tract are not uncommon. Hairpins, glass rods, umbilical tapes, ball point pen are described in lower urogenital tract. Retained gauze piece (gossypiboma) in posterior urethra may cause diagnostic dilemma. Symptoms and investigations may mimic stricture of posterior urethra. PRESENTATION OF CASE: Two cases of retained gauze pieces in the urethra are described here. The micturating cystourethrogram was suggestive of posterior urethral stricture. DISCUSSION: Two cases described here had retained gauze piece as a cause of filling defect and abnormal appearance in the micturating cystourethrogram. Gossypiboma may be a possibility where posterior urethral stricture are seen after previous surgery in paediatric age group. CONCLUSION: In the setting of previous urogenital surgery gossypiboma should be kept in the differential diagnosis where posterior urethral stricture are seen in the paediatric age group.