A Lumped Parameter Method to Calculate the Effect of Internal Carotid Artery Occlusion on Anterior Cerebral Artery Pressure Waveform.

BACKGROUND AND OBJECTIVE: Numerical modeling of biological structures would be very helpful tool to analyze hundreds of human body phenomena and also diseases diagnosis. One physiologic phenomenon is blood circulatory system and heart hemodynamic performance that can be simulated by utilizing lumped method. In this study, we can predict hemodynamic behavior of one artery of circulatory system (anterior cerebral artery) when disease such as internal carotid artery occlusion is occurred. METHOD: Pressure-flow simulation is one the leading common approaches for modeling of circulatory system behavior and forecasts of hemodynamic in numerous physiological conditions. In this paper, by using lumped model (electrical analogy), CV system is simulated in MATLAB software (SIMULINK environment). RESULTS: The performance of healthy blood circulation and heart is modeled and the obtained results used for further analyses. The stenosis of internal carotid artery at different rates was, then, induced in the circuit and the effects are studied. In stenosis cases, the effects of internal carotid artery occlusion on  left anterior cerebral artery pressure waveform are investigated. CONCLUSION: The findings of this study may have implications not only for understanding the behavior of human biological system at healthy condition but also for diagnosis of diseases in circulatory and cardiovascular system of human body.

Evaluation of the effects of injection velocity and different gel concentrations on nanoparticles in hyperthermia therapy.

BACKGROUND AND OBJECTIVE: In magnetic fluid hyperthermia therapy, controlling temperature elevation and optimizing heat generation is an immense challenge in practice. The resultant heating configuration by magnetic fluid in the tumor is closely related to the dispersion of particles, frequency and intensity of magnetic field, and biological tissue properties. METHODS: In this study, to solve heat transfer equation, we used COMSOL Multiphysics and to verify the model, an experimental setup has been used.  To show the accuracy of the model, simulations have been compared with experimental results. In the second part, by using experimental results of nanoparticles distribution inside Agarose gel according to various gel concentration, 0.5%, 1%, 2%, and 4%, as well as the injection velocity, 4 µL/min, 10 µL/min, 20 µL/min, and 40 µL/min, for 0.3 cc magnetite fluid, power dissipation inside gel has been calculated and used for temperature prediction inside of the gel. RESULTS: The Outcomes demonstrated that by increasing the flow rate injection at determined concentrations, mean temperature drops. In addition, 2% concentration has a higher mean temperature than semi spherical nanoparticles distribution. CONCLUSION: The results may have implications for treatment of the tumor and any kind of cancer diseases.

Tension pneumocephalus following pterional craniotomy for treatment of intracavernous internal carotid artery aneurysm.

The occurrence of tension pneumocephalus following intracranial aneurysm surgery is a rare event. Here, we present a case of extradural tension pneumocephalus following pterional craniotomy for the treatment of intracavernous internal carotid artery aneurysm. It has been caused by a fistulous communication between the posterior wall of the frontal sinus and the extradural space. Successful obliteration of this aberrant communication tract was performed using fibrin glue, with complete resolution of the pneumocephalus.

How to decrease cardiovascular mortality in renal transplant recipients.

Cardiovascular disease is the leading cause of death following renal transplantation, accounting for 40% to 55% of all deaths. An analysis in our center showed a 15% mortality in a cohort of renal transplant recipients followed for an average of 10 years. Various contributing risk factors of cardiovascular diseases in transplant recipients such as tobacco use, hypertension, hyperlipidemia, hereditary risk, diabetes, physical inactivity, obesity, dialysis duration, hyperuricemia, proteinuria, hyperhomocysteinemia, hyperparathyroidism, anemia; C-reactive protein level, and immunosuppressive regimen as well as some rare risk factors, such as cytomegalovirus infection, were evaluated in a population of 1200 kidney transplant recipients. Also we introduced methods for early detection, monitoring, and follow-up of proven risk factors of cardiovascular disease.

Complications of arteriovenous fistula in dialysis patients.

Repeated access to the circulation is essential to perform adequate maintenance hemodialysis (HD). Dysfunction of fistulae is the most common reason for a second intervention and recurrent hospitalization. The aim of this study was to evaluate the complications of HD fistulas seeking to evaluate the impact of age, site of arteriovenous fistula (AVF) (proximal or distal), side (left or right), and history of previous vascular access. We evaluated the clinical complications in 273 patients from the beginning of the use of the current access using the history and physical examination obtained at every dialysis session. We performed further investigations including doppler ultrasound or spiral computed tomography to confirm the clinical diagnosis. Of our patients, 40% had diabetes mellitus as the cause of end-stage renal disease. Almost half (49%) the patients dialyzed through an AVF and 13% with a catheter. One hundred eighty-four cases (67.6%) experienced complications. Of 145 cases that had elbow AVFs, 103 cases (71%) had complications; of 128 cases with wrist AVFs, 80 cases (62.5%) had complications. There were 115 (62.5%) complicated cases among 185 patients with left AVFs, and 69 (78%) among 88 patients with right AVFs. The rate of AVF complications increased with age. The 1-year survival rate was 94%. We did not observe any significant difference between AVF complications in patients with diabetes mellitus or hypertension as the underlying cause of renal failure. Mean cholesterol plasma level did not differ significantly between the patients with and without AVF complications. Mean hematocrit levels were not significantly different between the two groups. However, mean EPO weekly dose was significantly higher among the group of patients with AVF complications. We did find that rate of complications increased with age (P<.05). Our results showed that the frequency of complications was higher among patients with elbow and right-side AVFs, and also among patients with a history of a previous failed shunt but no significant relationship was observed between these variables (P>.05).

Long-term results of renal transplantation: A single-center analysis of 1200 transplants.

The present study is a report of long-term results of the first 1200 operations from December 1988 to December 2003. Graft and patient survival rates in eligible cases were computed with Kaplan-Meier analysis. Recipients were 808 men, 392 women of mean age 33.6 +/- 12.5 years. Eighty six percent of cases used organs from living donors (40% related, 41% unrelated, and 5% spouses) and 14% from cadaveric source. The most common causes of end-stage renal disease were chronic glomerulonephritis (18.2%); reflux nephropathy (13.4%); and diabetic nephropathy (10.1%). Among 215 (17.9%) patients, 156 patients (13%) died in the posttransplant period. Most common causes of death were cardiovascular (28.3%), graft loss (20.7%), and infections (19.6%). The 1- and 3-year patient survival rates were 94% and 91.5%, and graft survival rates were 88% and 84%. Although the success rate of operations was not satisfactory at the beginning, the current data reflect a >90% survival rate comparable to the major centers in the world.

Comparison of spousal with other donor groups: Study of a single center.

In coping with the shortage of living-related and cadaveric donor groups for renal transplantation, and in the fear of organ marketing, spousal donors are considered an invaluable potential source. Survival rates have been reported to be as high as even some related groups. This study evaluated 1039 renal transplantations up to 2003. Patient survival rates in different donor groups were determined using the Kaplan-Meier method. The 3-year patient survival rates were 93% for kidneys from 61 spouses; 92% for kidneys from 433 living-related donors; 91% for kidneys from 427 living-unrelated (excluding spouses) donors; and 90.5% for 118 cadaveric kidneys. Such results were consistent with many other reports which consistently showed that spousal donors were at least as good as living-related donors, representing a reliable source in cases of organ shortage. The high survival rate of spousal donors is probably related to their strong emotional support.

Effect of body mass index at time of transplantation and weight gain after transplantation on allograft function in kidney transplant recipients in Shiraz.

Chronic renal allograft dysfunction is the most common cause of graft loss, for which there are multiple risk factors, including obesity before transplantation, which is believed to lower long-term renal allograft survival. One hundred eighty-two kidney transplant recipients were studied. Body mass index (BMI) at the date of transplantation was calculated. BMI values were classified into 4 categories: (1) patients with BMI <20, (2) BMI between 20 and <25, (3) BMI between 25 and <30, and (4) BMI > or =30. The minimum follow-up period in this study was 3 years after transplantation. The link between categorized BMI and the presence of renal allograft dysfunction and mortality within 3 years posttransplantation was investigated using independent sample t test. BMI at the date of transplantation showed statistically significant association with presence of renal allograft dysfunction and mortality within 3 years posttransplantation (P = .008, P = .01, respectively). BMI at the date of transplantation has a strong association with outcomes after renal transplantation. The extremes of very high and very low BMI are important risk factors for chronic renal allograft dysfunction; therefore, weight adjustment before kidney transplantation can be useful in improving the function of a transplanted kidney and increasing patient's survival.

Incidence of posttransplantation diabetes mellitus in kidney transplantation: a single-center experience.

Posttransplantation diabetes mellitus (PTDM) is a well-recognized complication of renal transplantation. PTDM is reported to contribute to major infections and cardiovascular complications and leads to increased posttransplantation morbidity. The present study was conducted to evaluate the frequency of PTDM in our center, to identify the role of immunosuppressive therapy and other risk factors in the genesis of PTDM, and to assess the impact of PTDM on graft and patient survival. From December 1998 to December 2003 we followed-up 1200 renal transplant recipients, including 121 recipients with pretransplantation diabetes mellitus and 1079 recipients without diabetes. PTDM occurred in 203 patients (mean age, 35.4 +/- 5.9 years); 131 (64.5%) were male. Graft loss and mortality were significantly higher in patients with PTDM versus those without. The overall reported incidence of PTDM worldwide varies from 3.4% to 46%. The incidence in our center is 18.8%. We also found a significantly higher incidence of PTDM among patients receiving grafts from living-related donors. This may be related to the higher cumulative doses of immunosuppressive drugs administered (in part, due to the greater number of acute rejections) in these patients.

Results of liver transplantation: analysis of 140 cases at a single center.

The Shiraz Organ Transplant Center in southern Iran has been performing all liver transplantations in Iran and certain neighboring countries for 12 years. This study evaluated the 140 operations performed from April 1993 through November 2004. Sixty-one percent of the recipients were men and 39% were women. The average recipient age was 29.9 +/- 14.0 years. One hundred twenty-eight patients has a full-size cadaveric transplant. Most frequent causes of cirrhosis were cryptogenic and viral. An acute rejection episode occurred in 47.5% of cases, and two episodes in 8%. Most frequent short-term complications included respiratory, neurologic, and biliary problems. The 1-, 2-, and 3-year patient survival rates were 92%, 89%, and 85%, respectively. The experience that the Shiraz Organ Transplant Center has had with liver transplantation indicated success comparable to that noted in other reports. The calculated trend suggests that a goal of 100 transplantations for 2005 is within reach.

Biliary tract complications after liver transplantation in a single center.

Biliary tract complications, which occur in 5.8% to 24.5% of adult liver transplant recipients, remain one of the most common problems following transplantation. The aim of this study was to determine the incidence of biliary complications and analyze methods of treatment. From 1993 to 2004, 14 cases (10%) among 140 patients who had undergone liver transplantation developed biliary complications, third to respiratory and neurologic complications. In addition to biliary leakage in six cases, obstruction/stenosis occurred in three cases. One case of biliary fistula and one vanishing bile duct syndrome were observed. There was no death or need for retransplantation; all cases were treated surgically without recurrence. Biliary complications remain an important problem in liver transplantation. Endoscopic and radiologic management are effective in the majority of cases. Surgical intervention is obligatory and safe in selected cases.

Anthrax: pathological aspects in autopsy cases in Shiraz, Islamic Republic of Iran, 1960-2001.

Anthrax, like tuberculosis, shows a new epidemic spread in industrialized countries, revealing some ambiguous aspects to the disease and providing new challenges to medicine. Shiraz University of Medical Sciences has records of 7130 autopsies performed in the past 40 years, 33 of which are anthrax cases. We reviewed all the pathology slides of these cases and classified the organs involved in a search for unrecognized microscopic findings. The most common cause of death was sepsis, caused by organ involvement and direct cytotoxicity of Bacillus anthracis, in addition to its exotoxin production. Novel findings included hyaline membrane formation in respiratory system cases that is similar to acute (adult) respiratory distress syndrome and evidence of primary gastrointestinal involvement, showing the ability of the organism to pass the gastric barrier.

Anthrax: pathological aspects in autopsy cases in Shiraz, Islamic Republic of Iran, 1960-2001

Anthrax, like tuberculosis, shows a new epidemic spread in industrialized countries, revealing some ambiguous aspects to the disease and providing new challenges to medicine. Shiraz University of Medical Sciences has records of 7130 autopsies performed in the past 40 years, 33 of which are anthrax cases. We reviewed all the pathology slides of these cases and classified the organs involved in a search for unrecognized microscopic findings. The most common cause of death was sepsis, caused by organ involvement and direct cytotoxicity of Bacillus anthracis, in addition to its exotoxin production. Novel findings included hyaline membrane formation in respiratory system cases that is similar to acute [adult] respiratory distress syndrome and evidence of primary gastrointestinal involvement, showing the ability of the organism to pass the gastric barrier