Evaluation of venocutaneous fistula as vascular access for hemodialysis: Examination of 46 limbs of 40 patients.

INTRODUCTION: We have previously evaluated the usefulness of venocutaneous fistula (VCF), also called "dermatorrhea." VCF is a technique of blood removal/return by advancing a dialysis cannula to the femoral vein for each hemodialysis session using a fistula created between the great saphenous vein and skin. METHODS: In this study, we evaluated 46 limbs of 40 patients for whom VCF was created at our hospital between May 2017 and April 2022. In all the patients, it was difficult to construct an arteriovenous fistula or arteriovenous graft because of the general/vascular conditions. The usefulness of this method was evaluated based on the results of dialysis treatment after fistula creation and the use of fistula. RESULTS: Fundamental evaluation confirmed the progression of vascular wall thickening over time. During clinical review, no serious complications were found in any patient during or after fistula creation surgery. The infection rate was 0.30/1000 days of fistula maintenance. Secondary patency rates by the Kaplan-Meier method were 87.0% at 1 year and 42.6% at 3 years. CONCLUSION: This method has demonstrated a good patency rate, low infection rate, and seems to be a potentially useful alternative in patients in whom it is difficult to establish vascular access.

Effect of Early Cannulation with Plastic Cannula on Arteriovenous Fistula Patency in Hemodialysis Patients.

INTRODUCTION: Plastic cannulas have been used to cannulate arteriovenous fistulas (AVFs) for hemodialysis (HD) in Japan for many years. However, the effect of early cannulation with plastic cannulas on AVF patency is not known. OBJECTIVE: We analyzed the relationship between first cannulation time (FCT) and patency rates for AVFs cannulated with plastic cannulas and investigated whether early cannulation with plastic cannulas affects AVF patency. METHODS: In total, 122 patients who underwent primary AVF construction were divided into an early cannulation group (FCT <10 days) and a late cannulation group (FCT ≥10 days). The Kaplan-Meier method and multivariable Cox regression models were used to investigate AVF patency. RESULTS: Median FCT was 6 days. There was no statistically significant between-group difference in primary (p = 0.643) or secondary (p = 0.453) patency rates. Early or late cannulation was not significantly associated with primary patency (hazard ratio [HR] 1.21; 95% CI 0.71-2.05) or secondary patency (HR 0.46; 95% CI 0.08-2.77) after adjustment for age, sex, presence of diabetes mellitus or hypertension, and HD at baseline. CONCLUSIONS: Early AVF cannulation (<10 days from creation) with plastic cannulas does not affect access patency, and it may be possible to cannulate AVFs earlier than 10 days to decrease the need for use of a central venous catheter.

Ultrasound-guided removal of organized thrombi using biopsy forceps in dialysis patients with arterio-venous access occlusion.

INTRODUCTION: As a countermeasure against the organized thrombi frequently observed in vascular access occlusion, we devised a percutaneous excision method for organized thrombi under superficial ultrasound guidance using biopsy forceps. The Radial JawTM 3 (2 mm) biopsy forceps of Boston Scientific Corporation was used. The usefulness of this method was investigated. METHOD: The following protocol, which is suitable for endovascular treatment, was prepared and used: (1) all procedures were performed under ultrasound guidance and (2) use of the forceps was assisted via a long sheath in cases involving a complicated bloodstream. SUBJECTS: Among 564 cases of arterio-venous access occlusion that received treatment at this hospital between May 2014 and April 2017, the subjects of this study were 468 cases who could be followed up. Thrombectomy of an organized thrombus using the biopsy forceps was performed 194 times in 138 cases. Biopsy forceps were used in the initial treatment in a total of 115 cases, including 71 cases of acute occlusion of an autologous vein, 3 cases of chronic occlusion of an autologous vein, and 41 cases of acute occlusion of a prosthetic vessel. RESULTS: The initial success rate for all cases of occlusion was 97.2%. The initial success rate for cases in which biopsy forceps were used was 98.2%. For cases using biopsy forceps, the primary patency rates were 47.1% at 3 months, and the secondary patency rates (until occlusion) were 89.1% at 3 months. CONCLUSION: This method was considered to be a valuable choice as a countermeasure against organized thrombi.

A new access, Dermatorrhea, 10 samples of the great saphenous vein.

We devised a method that enables blood removal/return by creating a fistula between the skin and the great saphenous vein to insert the dialysis needle sheath in the femoral vein under ultrasonography guidance with respect to each dialysis. We report the principles, methods, and cases. A skin-great saphenous vein fistula is created under local anesthesia. It is used for blood removal/return during maintenance hemodialysis performed immediately after creating the fistula. Ten limbs of 10 patients (three men and seven women; mean age, 77.6 ± 4.8 years; dialysis history, 9.9 ± 13.0 years), where skin-great saphenous vein fistulas were created in our hospital between May 2017 and June 2018, were included. In all the cases, an arteriovenous fistula or arteriovenous graft was difficult to create because of the general condition and/or vascular fitness of the patients. During or after the fistula-creating surgery, no serious complications were found. No complications such as blood removal failure, infection, or hemorrhage were found during the follow-up period. The primary patency rates by the Kaplan-Meier method were 100% at 3 months and 67.5% at 6 months. This method is considered a valuable substitute method for cases with difficulty in creating a vascular access.

Ultrasound-guided endovascular treatment for vascular access malfunction: results in 4896 cases.

PURPOSE: For the protracted maintenance of vascular access, countermeasures against stenosis are important. Between March 2004 and October 2011 superficial ultrasound-guided percutaneous transluminal angioplasty (PTA) was performed in our hospital for arteriovenous fistula malfunction in 4869 cases in 1011 patients, and the utility of the treatment was assessed on the basis of early results. In cases where vascular intervention was deemed necessary, the procedure was conducted under ultrasound guidance as first option, with fluoroscopy and radiography used additionally as necessary.
 METHODS: The ultrasound apparatus used was primarily the 11 MHz linear-type probe (GE-Yokogawa Logiq S6). For subclavian and brachiocephalic veins, the microconvex-type probe was used to visualize the lesion through the intercostal space. In obstruction cases, ultrasound-guided PTA was performed after superficial ultrasound-guided aspiration or thrombus removal. 
 RESULTS: In stenosis cases, early success (technical and clinical) was obtained in 4288 of 4414 cases (97.1%). In obstruction cases, early success was obtained in 443 cases and 91.9% for obstruction cases. Assistance by intra-operative fluoroscopy or radiography was required in 55 cases, and surgical reconstruction was required in 42 cases. Serious complications occurred in 12 of 4869 cases (0.2%).
 CONCLUSIONS: Ultrasound-guided PTA for arteriovenous fistula malfunction could be used as a substitute for fluoroscopy-guided PTA, and enables the use of safe and rapid intervention techniques.

Kinetic resolution of racemic α-tert-alkyl-α-hydroxy esters by enantiomer-selective carbamoylation.

Kinetic resolution of sterically hindered racemic α-tert-alkyl-α-hydroxy esters is performed by enantiomer-selective carbamoylation with the t-Bu-Box-Cu(II) catalyst (Box = bis(oxazoline)). The reaction with 0.5 equiv of n-C(3)H(7)NCO is carried out with a substrate-to-catalyst molar ratio of 500-5000 at -20 to 25 °C. The high enantiomer-discrimination ability of the catalyst achieves an excellent stereoselectivity factor (s = k(fast)/k(slow)) of 261 in the best case. A catalytic cycle for this reaction is proposed.

Enantiomer-selective carbamoylation of racemic alpha-hydroxy gamma-lactones with chiral Cu(II) Catalysts: an example of a highly active Lewis acid catalyzed reaction.

Enantiomer-selective carbamoylation of racemic alpha-hydroxy gamma-lactones with half equivalents of isocyanates in the presence of chiral Cu(II) catalysts was studied. Among a series of catalyst bearing chiral bis(oxazoline) (box) and pyridine(bisoxazoline) ligands, [Cu(tBu-box)]X(2) [X=OSO(2)CF(3) (3 a), SbF(6) (3 b)] showed the highest enantioselectivity in the reaction of pantolactone (1 a). Use of n-C(3)H(7)NCO, a small alkyl isocyanate, in CH(2)Cl(2) solution was important to achieve a high level of enantiomer selection. The tBu-box-Cu(II) catalyst efficiently differentiated two enantiomers of beta-substituted alpha-hydroxy gamma-lactones under the optimized reaction conditions, resulting in a stereoselectivity factor (s=k(fast)/k(slow)) of up to 209. Furthermore, this catalyst is highly active, so that the carbamoylation can be conducted with a substrate-to-catalyst molar ratio of 2000-3000. A catalytic cycle of this reaction is also proposed.

Isolation and characterization of Acidithiobacillus ferrooxidans strain D3-2 active in copper bioleaching from a copper mine in Chile.

Acidithiobacillus ferrooxidans strain D3-2, which has a high copper bioleaching activity, was isolated from a low-grade sulfide ore dump in Chile. The amounts of Cu(2+) solubilized from 1% chalcopyrite (CuFeS(2)) concentrate medium (pH 2.5) by A. ferrooxidans strains D3-2, D3-6, and ATCC 23270 and 33020 were 1360, 1080, 650, and 600 mg x l(-1) x 30 d(-1). The iron oxidase activities of D3-2, D3-6, and ATCC 23270 were 11.7, 13.2, and 27.9 microl O(2) uptake x mg protein(-1) x min(-1). In contrast, the sulfite oxidase activities of strains D3-2, D3-6, and ATCC 23270 were 5.8, 2.9, and 1.0 mul O(2) uptake.mg protein(-1).min(-1). Both of cell growth and Cu-bioleaching activity of strains D3-6 and ATCC 23270, but not, of D3-2, in the chalcopyrite concentrate medium were completely inhibited in the presence of 5 mM sodium bisulfite. The sulfite oxidase of strain D3-2 was much more resistant to sulfite ion than that of strain ATCC 23270. Since sulfite ion is a highly toxic intermediate produced during sulfur oxidation that strongly inhibits iron oxidase activity, these results confirm that strain D3-2, with a unique sulfite resistant-sulfite oxidase, was able to solubilize more copper from chalcopyrite than strain ATCC 23270, with a sulfite-sensitive sulfite oxidase.

The oxalate level in ultrafiltrate fluid collected from a dialyzer is useful for estimating the plasma oxalate level in hemodialysis patients.

BACKGROUND: Patients on chronic hemodialysis are likely to develop secondary hyperoxalemia. It is, however, difficult to measure plasma oxalate levels. To measure plasma oxalate levels, rapid plasma separation, deproteinization, and acidification are essential in preventing the formation of oxalate and the deposition of calcium oxalate within the test tube. The present study was undertaken to examine whether the oxalate level in dialyzer ultrafiltrate is potentially useful for estimating plasma oxalate levels. METHODS: In nine patients on chronic hemodialysis, the plasma, after deproteinization with a filter, and the ultrafiltrate from the dialyzer before hemodialysis were acidified to a pH level of less than 3, followed by the measurement of oxalate levels by ion chromatography. Also, oxalate levels were compared between acidified and non-acidified ultrafiltrates from the dialyzer. In the second part of the study, seven patients on chronic hemodialysis receiving erythropoietin therapy, in whom the ferritin level was more than 300 ng/ml and transferrin saturation was less than 25%, were intravenously administered ascorbic acid, 100 mg, three times a week, after each dialysis session to facilitate the utilization of stored iron. This treatment was continued until the serum ferritin level decreased to a level below 300 ng/ml (for 3 months, at a maximum). The oxalate level in the dialyzer ultrafiltrate after this treatment was compared with that before treatment. RESULTS: The mean +/- SE oxalate level in the dialyzer ultrafiltrate was 45 +/- 6 micromol/l, essentially equal to the plasma oxalate level (46 +/- 7 micromol/l). The plasma oxalate level had a significant positive correlation with the dialyzer ultrafiltrate oxalate level (plasma oxalate level = 0.99 x dialyzer ultrafiltrate oxalate level + 1.5; r = 0.95; P < 0.0001). The oxalate level in the acidified ultrafiltrate (45 +/- 6 micromol/l) did not differ significantly from that in the non-acidified ultrafiltrate (45 +/- 6 micromol/l). The mean +/- SE duration of ascorbic acid administration was 64 +/- 13 days. The hemoglobin level remained unchanged at 9.6 +/- 0.4 g/dl, whereas the serum iron level increased significantly, from 34 +/- 2 microg/dl to 43 +/- 4 microg/dl (P < 0.05), and serum ferritin levels decreased significantly, from 645 +/- 219 ng/ml to 231 +/- 30 ng/ml after the treatment (P < 0.05). The oxalate level in the acidified ultrafiltrate showed no significant change after ascorbic acid administration (31 +/- 8 micromol/l vs 47 +/- 7 micromol/l). CONCLUSIONS: In patients on chronic hemodialysis, the oxalate level in acidified ultrafiltrate from the dialyzer was found to be useful for estimating the plasma level of non-protein-bound oxalate. When administering ascorbic acid to hemodialysis patients, the plasma oxalate level can be monitored using this method.

[Comparison of intravenous ascorbic acid versus intravenous iron for functional iron deficiency in hemodialysis patients].

The effect of intravenous ascorbic acid was compared with that of intravenous iron in the treatment of functional iron deficiency, as defined as serum ferritin levels over 300 ng/ml and serum iron levels below 50 microg/dl, in patients on chronic hemodialysis. Thirteen patients on chronic hemodialysis with functional iron deficiency received intravenous injections of ascorbic acid, 100 mg, three times a week, after hemodialysis. The therapy was continued until serum ferritin decreased to below 300 ng/ml (3 months at the maximum). The iron and control group were composed of patients who had serum iron levels below 50 microg/dl within 3 months after serum ferritin rose to over 300 ng/ml. Seven patients with the iron group received more than a total of 10 intravenous injections of saccharated ferric oxide (40 mg/dose) after hemodialysis, and seven patients with the control group received no iron preparation during the 3 months. In the ascorbic acid group, while hemoglobin did not change from 10.9 +/- 0.5 g/dl (mean +/- SE) during the three-month period, serum iron increased significantly from 37 +/- 4 microg/dl to 49 +/- 4 microg/dl after one month (p<0.01), and remained elevated until the end of the three-month period. Serum ferritin decreased significantly from 607 +/- 118 ng/ml to 354 +/- 30 ng/ml after 3 months (p<0.01). In the iron group, hemoglobin and serum iron increased significantly from the respective pre-treatment levels during the 2-month period, and serum ferritin rose significantly after 3 months. In the control group, hemoglobin, serum iron and ferritin levels decreased significantly from the respective pre-treatment levels during the 3 months. The recombinant erythropoietin dose remained stable for three months in the ascorbic acid, iron, and control groups, respectively. These results suggest that in hemodialysis patients with a functional iron deficiency, treatment with intravenous ascorbic acid can prevent iron overload due to treatment with intravenous iron, and provide a useful adjuvant means of maintaining hemoglobin and serum iron levels.

[The clinical evaluation of maxacalcitol on therapy for secondary hyperparathyroidism of chronic hemodialysis patients].

The spectrum of bone disease in end-stage renal failure is changing, but secondary hyperparathyroidism is still a troublesome complication. The vitamin D3 analog, maxacalcitol, has reduced calcemic action compared to vitamin D3, but show equivalent suppression of parathyroid hormone(PTH) secretion. In the first step of the study, we investigated the severity of secondary hyperparathyroidism in 670 chronic hemodialysis patients, whose age, sex(male/female), and duration on dialysis were 63.5 +/- 12.4 years, 383/287, and 7.3 +/- 6.0 years, respectively. The number of patients with serum intact-PTH concentrations over 300 pg/ml was 118. Most patients in this group(87.3%) were already being prescribed oral vitamin D3 analog. In the second step, maxacalcitol was administered intravenously, instead of the oral vitamin D3 analog, to 92 patients selected from the above-described group. The age, sex(male/female), and duration of dialysis were 59.4 +/- 11.5 years, 56/36, and 7.3 +/- 6.0 years, respectively. Serum intact-PTH concentration and alkaline phosphatase activity decreased significantly, from 612.3 +/- 32.7 to 414.2 +/- 26.8 pg/ml, and from 329.3 +/- 17.3 to 277.0 +/- 12.5 IU/l, respectively. Serum calcium phosphorous concentration increased significantly, and maxacalcitol administration was interrupted because of hypercalcemia in 17 patients(18.5%). Serum intact-PTH concentration did not decrease in patients with serum Ca concentrations of 10.5 mg/dl or more before maxacalcitol therapy. In conclusion, maxacalcitol suppressed PTH secretion more effectively in hemodialysis patients with secondary hyperparathyroidism than did oral active vitamin D3 therapy, especially in patients with serum Ca concentrations lower than 10.5 mg/dl.