Back to the Future: How Biology and Technology Could Change the Role of PTFE Grafts in Vascular Access Management

Although the arteriovenous fistula (AVF) is the preferred mode of dialysis vascular access, AVF maturation failure remains a huge clinical problem, often resulting in a prolonged duration of use of tunneled dialysis catheters. In contrast, polytetrafluoroethylene (PTFE) grafts do not suffer from early failure, but have significant problems with later stenosis and thrombosis. This review will initially summarize the pathology and pathogenesis of PTFE graft dysfunction and will then use this as a basis for describing some novel therapies, which may have the potential to reduce PTFE graft dysfunction. Finally, we will emphasize that the introduction of such therapies could be an important first step toward individualizing overall vascular access care.     

Association of circulating interleukin (IL)-12- and IL-10-producing dendritic cells with time posttransplant, dose of immunosuppression, and plasma cytokines in renal-transplant recipients

BACKGROUND: Interleukin (IL)-12-producing dendritic cells (IL-12+DC) polarize T helper (Th) differentiation toward Th1, whereas IL-10+DC induce Th differentiation toward Th2. We investigated DC and plasma cytokine patterns early and late after transplantation. METHODS: Twenty-five hospitalized renal-transplant recipients without acute rejection or infection early (<40 days) posttransplant, 32 symptom-free outpatients with long-term functioning transplants (2,762+/-2,423 days posttransplant), and 17 healthy controls were studied. The intracellular production of IL-12 and IL-10 in CD11c+ CD83+ CD40+ DC was measured in freshly obtained whole blood using four-color fluorescence flow cytometry. In addition, plasma cytokine levels were investigated. RESULTS: Early and late posttransplant patients had significantly lower proportions of IL-12+DC (early: P=0.001; late: P=0.034) and lower ratios of IL-12+/IL-10+DC (early: P=0.0001; late: P<0.0001) than healthy controls. IL-10+DC (P=0.0004) and IL-12+DC (P=0.002) increased with time posttransplant in association with dose reductions of cyclosporine (IL-10+DC: P=0.003; IL-12+DC: P=0.005), methylprednisolone (IL-10+DC: P<0.0001; IL-12+DC: P=0.001) and mycophenolate mofetil (IL-10+DC: P<0.0001; IL-12+DC: P=0.004). Both IL-10+DC and IL-12+DC were associated with low plasma IL-10 (IL-10+DC: P=0.010; IL-12+DC: P=0.011) and high plasma IL-6 (IL-10+DC: P=0.001; IL-12+DC: P=0.009). IL-10+DC were also associated with high plasma levels of IL-3 (P=0.003), interferon (IFN)-gamma (P=0.014), and IL-2 (P=0.058). CONCLUSION: IL-10+DC and IL-12+DC in peripheral blood are associated with time after transplantation and dosage of immunosuppression. IL-10+DC dominate late posttransplant in the presence of Th1 plasma cytokines (high IFN-gamma and IL-2), high IL-3, and low IL-10. These findings could be a reflection of immunoregulatory processes favoring long-term allograft acceptance.     

Chronic perforation of the sigmoid colon by foreign body

Colorectal foreign bodies (FBs) may be ingested or introduced transanally and then migrate proximally. Without a reliable history, it may be impossible to determine which way a certain colorectal FB gained access. We present a case of a nonverbal mentally retarded boy with a flat piece of plastic impacted in the sigmoid colon, the colonoscopic extraction of which failed. He underwent laparotomy more than a year later to remove the FB, where chronic perforation of the sigmoid colon was discovered. The perforation was sealed with extensive adhesions to the pelvic wall, and histologically, the colon showed a chronic granulomatous reaction. We discuss the types, presentations, and diagnosis of intestinal perforation with FBs. Chronic perforation may present with radiologic and pathologic features that suggest inflammatory bowel disease.     

Carnosine as a protective factor in diabetic nephropathy: association with a leucine repeat of the carnosinase gene CNDP1

The risk of diabetic nephropathy is partially genetically determined. Diabetic nephropathy is linked to a gene locus on chromosome 18q22.3-q23. We aimed to identify the causative gene on chromosome 18 and to study the mechanism by which the product of this gene could be involved in the development of diabetic nephropathy. DNA polymorphisms were determined in 135 case (diabetic nephropathy) and 107 control (diabetes without nephropathy) subjects. The effect of carnosine on the production of extracellular matrix components and transforming growth factor-beta (TGF-beta) after exposure to 5 and 25 mmol/l d-glucose was studied in cultured human podocytes and mesangial cells, respectively. A trinucleotide repeat in exon 2 of the CNDP1 gene, coding for a leucine repeat in the leader peptide of the carnosinase-1 precursor, was associated with nephropathy. The shortest allelic form (CNDP1 Mannheim) was more common in the absence of nephropathy (P = 0.0028, odds ratio 2.56 [95% CI 1.36-4.84]) and was associated with lower serum carnosinase levels. Carnosine inhibited the increased production of fibronectin and collagen type VI in podocytes and the increased production of TGF-beta in mesangial cells induced by 25 mmol/l glucose. Diabetic patients with the CNDP1 Mannheim variant are less susceptible for nephropathy. Carnosine protects against the adverse effects of high glucose levels on renal cells.     

Control of refractory status epilepticus precipitated by anticonvulsant withdrawal using left vagal nerve stimulation: a case report

OBJECTIVE: To describe a case of left vagal nerve stimulation (VNS) resulting in immediate cessation of status epilepticus (SE) with good neurological outcome. CASE DESCRIPTION: A 30-year-old man with medically intractable seizures including episodes of SE was successfully treated using left VNS. After requiring discontinuation of phenytoin, valproic acid, carbamazepine, and topiramate because of severe allergic reactions resembling Stevens-Johnson syndrome, the patient required pentobarbital coma along with phenobarbital, tiagabine, and levetiracetam for seizure frequency reduction. He underwent left vagal nerve stimulator placement after nearly 9 days of barbiturate-induced coma, with stimulation initiated in the operating room. On the following day, electroencephalography revealed resolution of previously observed periodic lateral epileptiform discharges and the patient was free of seizures. Prestimulation seizure frequency was recorded at 59 times a day, with some seizures enduring 45 minutes despite barbiturate coma. Poststimulation, the patient has been free of seizures for 19 days and is presently taking only levetiracetam and phenobarbital, from which he continues to be successfully weaned without seizures. He is awake, alert, and can recall events leading up to his seizures, with good long-term memory and residual left upper extremity and lower extremity weakness. CONCLUSION: This case illustrates the role of left vagal stimulation in the treatment of SE and otherwise medically intractable seizures caused by allergic reactions. To our knowledge, this is the first case in the world literature for adults reporting cessation of SE after VNS. Another case with a similar improvement has been reported in the pediatric population.     

Abnormal left ventricular relaxation and symptoms of heart failure

Objectives

The purpose of our study was to assess the echocardiographic and angiographic parameters in patients with symptomatic heart failure (HF) and mild diastolic dysfunction (grade I).

Background

It remains uncertain why some patients with mild diastolic dysfunction exhibit HF symptoms and others are asymptomatic.

Methods

The study enrolled 80 hospitalized patients with impaired left ventricular (LV) relaxation. Patients were divided into two groups; one group had chronic functional class II to III dyspnea and the other group had no symptoms of HF. After admission, echocardiography and coronary angiography were performed for all patients and LV systolic and diastolic parameters were compared between the two groups.

Results

More patients in the asymptomatic group were hypertensive (p-value: 0.012). However, coronary artery disease was more prevalent in symptomatic patients (p-value: 0.022). The LV ejection fraction (EF) was significantly lower in symptomatic patients [median 54.33 %, 95 % confidence interval (53.76–54.87 %) in asymptomatic patients and median 49.43, 95 % confidence interval (47.23–50.91 %) in symptomatic patients, p-value <0.001]. Furthermore, the systolic LV internal dimension was significantly larger in this group (p-value: 0.037). The results of logistic regression identified that only the absolute level of the LVEF was the negative determinant of the occurrence of HF in patients with impaired LV relaxation.

Conclusion

Our study showed that LV systolic performance has an important role in occurrence of HF symptoms in patients with grade I diastolic dysfunction.

     

Pylephlebitis: a Review of 95 Cases

Journal of Gastrointestinal Surgery - Pylephlebitis, or suppurative thrombophlebitis of the portal mesenteric venous system occurring in the setting of abdominal inflammatory processes, is a rare...     

Differentiation of renal cell carcinoma subtypes by multislice computerized tomography

Purpose

We differentiated renal cell carcinoma subtypes using multislice computerized tomography (CT).

Materials and Methods

We reviewed the CT images of 87 patients with renal cell carcinoma. Three subtypes of renal cell carcinoma were noted, including clear cell in 37 cases, papillary in 26 and chromophobe in 24. Biphasic CT (unenhanced, corticomedullary and excretory phases) was done in all patients. We compared patient age and sex, tumor size, enhancement degree and pattern (homogeneous, heterogeneous and predominantly peripheral), the presence or absence of calcification or cystic degeneration (necrotic or hemorrhagic areas within the tumor) and tumor spreading patterns, including perinephric change, venous invasion and lymphadenopathy, in the 3 subtypes.

Results

The degree of enhancement was significantly different among the 3 subtypes in the corticomedullary and excretory phases (p <0.001). Cystic degeneration was more evident in the clear cell subtype than in the other subtypes regardless of tumor size (p <0.001). A hypervascular pattern (higher tumor enhancement after contrast material injection due to higher vascularity) was noted in 48.6% of clear cell subtype in comparison to 15.4% of papillary and 4.2% of chromophobe subtypes (p <0.001). The chromophobe subtype showed homogeneous enhancement in 75% of cases in comparison to 45% and 65% of clear cell and papillary subtypes (p >0.05). Calcification was evident in 21.6%, 23.1% and 25% of clear cell, papillary and chromophobe subtypes, respectively (p >0.05).

Conclusions

To differentiate the subtypes of renal cell carcinoma the degree of enhancement is the most valuable parameter. The presence or absence of cystic degeneration, vascularity and enhancement patterns can serve supplemental role in differentiating renal cell carcinoma subtypes.     

The Concept of Tubularized Incised Plate Hypospadias Repair for Different Types of Hypospadias

Purpose: Using the concept of tubularized incised plate (TIP) urethroplasty technique for proximal, distal, primary, secondary and complicated cases of hypospadias. Material and methods: From June 2002 to December 2003 TIP urethroplasty was performed in 15 patients between the age of 1–18-year-old with penosecrotal, mid shaft and subcoronal hypospadias. In 13 of them TIP urethroplasty used as the primary repair while in two of them as secondary repair. Results: No clinically important complications were observed in those boys who underwent primary reconstruction. One of them had meatal stenosis at the early postoperative period which was corrected by dilatation of the external meatus by feeding catheter at intervals up to 2 months postoperatively. Three boys had very narrow fistula which just allow leak of few drops of urine through urination. One boy with penoscrotal hypospadias who underwent two-stage repair had fistula. Conclusion: The concept of TIP urethroplasty is the procedure of choice for the treatment of proximal hypospadias and, it seems to be suitable for distal, secondary and even complicated hypospadias reconstruction. The advantages of this procedure include its simplicity, low complication rates and very good appearance of the glance with normal meatus.