*2.3. Furfural Distillation*

Furfural spontaneously undergoes degradation when in contact with air [30]. For this reason, furfural was periodically purified, by means of distillation, to remove the degradation products from the starting material. A simple distillation was carried out by heating furfural in a round-bottom flask with a heating mantle (Fibroman-N, JP Selecta, Abrera, Spain). The vapors were channeled into a condenser, and the purified furfural was collected in another round-bottom flask. The flask was sealed, its content was bubbled with argon, and it was stored in a refrigerator at 4 ◦C.

## *2.4. Microwave-Assisted Aldol Condensation*

The aldol condensations were performed in an MW reactor (single reaction chamber microwave synthesis system, Milestone SynthWAVE, controlled by a Terminal 660 control panel with easyCONTROL software, Figure 1a). The reaction mixtures consisted of 0.1 g of furfural (86 uL, 1.04 mmol) in 5 mL of acetone, and the specified amounts of catalyst. The mixtures were placed in oven-dried glass reaction tubes together with magnetic stir bars; caps were put on to prevent the reaction mixtures from coming out of the tubes (Figure 1b). These tubes were placed in a rack, which was immersed in a heating bath. In all cases, this bath consisted of 250 mL of deionized water. The stirring was operated by a rotating magnetic stirrer, and the stirring rate was set to 50%. The whole PTFE reaction vessel was pressurized with 10 bars of N2. The maximum MW irradiation power was set to 300 W. The power was modulated by the system so that the real bath temperature matched the corresponding temperature in the program. Indeed, the temperature probe measures the temperature of the bath, and all temperatures mentioned in the rest of this article refer to the bath ones. The system did not measure the temperature of the reaction mixtures. The general structure of the temperature programs (Figure S1) was the following: in the first step, the temperature was increased to the desired temperature in 10 min; in the second step, this temperature was maintained for the rest of the reaction time; in the third step, the irradiation was stopped, and the bath temperature was allowed to decrease for 20 min to below 56 ◦C, the boiling point of acetone. Once the third step was over, the pressure was released, the reaction vessel was opened, and the reaction tubes were collected.

**Figure 1.** (**a**) Photograph of the microwave (MW) reactor, and (**b**) scheme of the reaction vessel during operation.

#### *2.5. Analysis of the Reaction Mixtures*

Samples were prepared from the final reaction mixtures by adding 100 μL of an internal standard (toluene, which is not formed in the reaction and is not reactive towards any of the reaction components), and then performing 1:5 dilutions with acetone to reduce the concentration of the reaction species and achieve better peak shapes and resolution in the GC analysis. The obtained samples were analyzed with a GC-2010 (Shimadzu, Kyoto, Japan) using a TRB-5 column (TR-120232, Teknokroma, Sant Cugat del Vallès, Spain; length: 30 m; film thickness: 25 μm; inner diameter: 0.25 mm). The product concentration was estimated from the calibration curve obtained for furfural, using the effective carbon number as a correction factor [31]. The conversion *X* of furfural was calculated as follows:

$$X\_{FLR} = \frac{n\_{FLR}^0 - n\_{FLR}}{n\_{FLR}^0} \cdot 100 \tag{1}$$

The yields, *Y*, of the various products and intermediates were calculated as follows:

$$Y\_{\rm C8} = \frac{n\_{\rm C8}}{n\_{\rm FIR}^0} \cdot 100 \qquad Y\_{\rm C8-OH} = \frac{n\_{\rm C8-OH}}{n\_{\rm FIR}^0} \cdot 100 \qquad Y\_{\rm C13} = \frac{2 \cdot n\_{\rm C13}}{n\_{\rm FIR}^0} \cdot 100 \tag{2}$$

The C8:C13 selectivity was defined as the ratio between the yields of the mono- and the double-condensation products. With our protocol, the standard deviations of both conversions and yields are below 5%. In addition, GC-MS was used to aid peak assignations. The samples were analyzed with a GCMS-QP-2010 (Shimadzu) using a Zebron ZB-5ms column (Phenomenex, Torrance, CA, USA). The results of these analyses can be found in the Supplementary Materials (Figure S2).

### **3. Results and Discussion**


**2. Techniques of renal artery embolization**

into blood vessel an obstruction material aimed to interrupt blood supply to an organ or to its particular region. At present different coils, haemostatic spongues, cyanoacrylic glues and alcohols are applied as materials for RAE [2, 11, 19]. This leads to acute necrosis of tis‐ sues where blood flow has been amputeed, which in turn results in development of acute

RAE is applied in treatment of RC for about 40 years [3]. It may be evoked prior to surgery, considered as a technique succouring the surgery, or used as palliative embolization in large, inoperable RC, mostly with intensive bleedings and/or pains. RAE which preceedes nephrectomy provides better conditions for the surgery and allows to shorten time of the intervention [1,4]. There exist informations that RAE may lead to stabilization and/or regres‐ sion of distal metastases. These effects may be due to immunomodulating effects of RAE suggested by some authors [1,5]. However, knowledge on influence of RAE on immune sta‐ tus and response of immunocompetent cells is still scarce and fragmentaric. Systematic stud‐

In view of multiple limitations in efficacy and safety of RAE the present indications for ap‐

**•** Palliative RAE in advanced RC which results in relief of life-treatening haematuria and

**•** Embolization of large, highly vascularized neoplasms prior to surgery (effective RAE results in contraction of vascular collaterals, facilitates dissection of the tumour, and allows to change the sequence of affixing renal vascular pedicle, ie first artery and the

Opinions on the role of preoperative RAE in the management of patients with RC are con‐ troversial. Although a significant number of studies on RAE are reported in RC patients, there is no consensus on the benefits and morbidity associated with the procedure [7, 22]. Moreover, many large studies on the use of RAE both prior to nephrectomy and in ad‐ vanced RC were conducted in the 1980s, before the development of improved techniques and imaging. Most proponents of preoperative RAE report the facilitation of nephrectomy through decreased operative blood loss, ease of dissection secondary to the development of oedema in tissue planes, and decreased operative time [8,9]. For those patients with signifi‐ cant tumour thrombus there might be a beneficial effect of decreasing the size or extent of tumour thrombus before surgery [10]. Interestingly, there might also be an advantage in the form of immunomodulation, whereby RAE-induced tumour necrosis stimulates a tumour-

Own experience [1] includes 474 patients with RC of which 118 had RAE before nephrec‐ tomy. It was reported that RAE significantly prolonged survival time in T2 and T3 RC. Additionally, it was found preliminarly that RAE exerted immunotropic effects and en‐ hanced immune status of the patients. This diminished risks of the surgery. Recently we‐ continued these investigations and performed series of studies on response of immune

**•** Embolization of highly vascularized RC metastases (e.g. vertebral metastases).

specific response from the immune system of the host [11-13].

phase reaction in the organism.

96 Renal Tumor

ies of this issue are needed.

lumbar pains;

renal vein later);

plication of this procedure include mostly [6, 7, 18]:

The initial indications developed in the 1970s for RAE were limited to symptomatic haema‐ turia and palliation for metastatic renal cancer [2,3]. With technical advances and growing experience the indications have broadened to include conditions such as vascular malforma‐ tions, medical renal disease, angiomyolipomas (AMLs), and preoperative infarction. The in‐ troduction of smaller delivery catheters and more precise embolic agents has drastically improved the morbidity associated with this technique [4]. RAE has continued to gain popu‐ larity as a minimally invasive approach for various urological conditions.

The technique of embolising hypervascular renal carcinomas dates back to 1969 when first reported by Lalli et al [2]. Since then, various techniques and embolic materials have been described. RAE has been used pre-operatively to facilitate nephrectomy [8], or to stimulate a possible systemic response in patients with metastases [5]. Renal embolisation has been es‐ tablished as a palliative treatment for unresectable renal carcinoma and in patients with less advanced disease (stage I–III) who, for whatever reason, are unsuitable or unwilling to un‐ dergo surgery [18, 22, 24]. In this group of patients the technique reduces tumour bulk and relieves local symptoms such as pain or intractable haematuria.

However, opinions on the role of preoperative RAE in the management of patients with RC are controversial. Although a significant number of studies on RAE are reported in these patients, there is no consensus on the benefits and morbidity associated with the procedure [7-9].

Effective embolization induces acute ischemic necrosis zone to form infarct of the organ tis‐ sues, which results in the onset of symptoms called postembolization syndrome, which usu‐ ally occurs within the first few days after RAE [8]. Greater risk of developing the postembolization syndrome occurs in patients with small tumors, developing peripherally, when still remains a large part of the normal, not embolized part of the kidney [9]. The side effects which occur after RAE include: pain in the lumbar region, nausea and vomiting, hy‐ perthermia, and fluctuations of blood pressure. These symptoms are usually temporary and transient, and their severity depends on the extent of ischemia in the kidney area. In a small percentage RAE may also lead to serious complications that are associated primarily with the movement (migration) or embolic material backflow [12, 22]. The consequence of this may be embolization of contralateral artery, mesenteric arteries, arteries of the lower limbs, and ischemic spinal cord injury. The risk of serious complications is low, if RAE is per‐ formed well and professionally. In our clinic material including hundreds of treatments was observed and serious complications developed, except of various symptoms of postemboli‐ zation syndrome [1].

If there is a real benefit to be gained, most proponents of preoperative RAE cite the facilita‐ tion of nephrectomy through decreased operative blood loss, ease of dissection secondary to the development of oedema in tissue planes, and decreased operative time [10, 11, 26]. For those patients with significant tumour thrombus there might be a beneficial effect of de‐ creasing the size or extent of tumour thrombus before surgery [12]. Interestingly, there might also be an advantage in the form of immunomodulation, whereby RAE-induced tu‐ mour necrosis stimulates a tumour-specific response [1,5,13]. It is likely that RAE is underu‐ tilized, perhaps because of a lack of prospective randomized studies demonstrating these potential benefits.

In our Departament of Clinical Urology the treatment of REA is performed under local anes‐ thesia wit 1% xylocaine after puncturing the femoral artery under fluoroscopic control [1,14]. Vascular catheter is inserted into the abdominal aorta (Seldinger method). Aorto‐ nephrography is performed as the first step of the procedure (Fig.1 - A). This is followed by selective catheterisation of renal arteries and contrast agent (usually Omnipac) is applied us‐ ing an automatic syringe (Fig. 1 - B). Image of arterial and venous intermediate is obtained with angiographic confirmation of following RC characteristics:

**Figure 1.** Stages of vascular embolization of renal artery. A. arteriography; B. vascularization of renal tumour; C. mate‐

Renal Artery Embolization in Treatment of Renal Cancer with Emphasis on Response of Immune System

http://dx.doi.org/10.5772/54116

99

After completing the RAE procedure the femoral artery puncture site is deemed temporary with pressure dressing. Few hours after RAE standard blood tests, monitoring of urine out‐ put and assessment of severity of postembolization symptoms (lumbar pain - a symptom that occurs in nearly all patients after effective RAE, nausea, vomiting, fever, transient renal failure and symptoms of gastrointestinal paralytic ileus). Medication (analgesic, antispas‐ modic, prokinetic agents, anticoagulants drugs and antibiotics) are prescribed appropriately to symptoms and depending on the clinical situation. In the study group of 474 patients there were no clinically significant complications (death, femoral hematoma, migration of

Time schedules of RAE and nephrectomy are not established precisely, usually RAE is made few – several days before nephrectomy. In some cases RAE is made one only day before sur‐

**3. Survival of renal cancer patients treated with renal artery embolization**

Up to 30% of patients diagnosed with RC have metastatic disease at presentation [27]. De‐ spite its sometimes favourable course, patients with metastatic RC generally die within 2 years of diagnosis. DeKernion et al [20] found that cumulative survival in 86 patients with metastatic RCC was 53% at 6 months, 43% at 1 year, 26% at 2 years and 13% at 5 years. The

rial for embolization injected to renal artery; D. closed renal artery.

embolizing material or ischemic spinal cord injury) [1,14].

gery to avoid acute postembolization syndrome.

This is followed by injecting the embolizing material through a vascular catheter. Most frequently used is Spongostan which is fragmented and placed at the end of a syringe filled with 0.9% NaCl, and then injected into renal artery. Spongostan embolization often supplemented with different coils. In case of confirmation in renal arteriography of tu‐ mor vascularization by more than one artery, respectively all the supplying vessels are embolized, as above.

The whole procedure of RAE (Fig. 1 A – D) lasts about 30 – 60 minutes and its effectiveness (lack of blood flow in renal vessels) is confirmed in angiography after re-injection of contrast medium through the catheter withdrawn to the aorta.

perthermia, and fluctuations of blood pressure. These symptoms are usually temporary and transient, and their severity depends on the extent of ischemia in the kidney area. In a small percentage RAE may also lead to serious complications that are associated primarily with the movement (migration) or embolic material backflow [12, 22]. The consequence of this may be embolization of contralateral artery, mesenteric arteries, arteries of the lower limbs, and ischemic spinal cord injury. The risk of serious complications is low, if RAE is per‐ formed well and professionally. In our clinic material including hundreds of treatments was observed and serious complications developed, except of various symptoms of postemboli‐

If there is a real benefit to be gained, most proponents of preoperative RAE cite the facilita‐ tion of nephrectomy through decreased operative blood loss, ease of dissection secondary to the development of oedema in tissue planes, and decreased operative time [10, 11, 26]. For those patients with significant tumour thrombus there might be a beneficial effect of de‐ creasing the size or extent of tumour thrombus before surgery [12]. Interestingly, there might also be an advantage in the form of immunomodulation, whereby RAE-induced tu‐ mour necrosis stimulates a tumour-specific response [1,5,13]. It is likely that RAE is underu‐ tilized, perhaps because of a lack of prospective randomized studies demonstrating these

In our Departament of Clinical Urology the treatment of REA is performed under local anes‐ thesia wit 1% xylocaine after puncturing the femoral artery under fluoroscopic control [1,14]. Vascular catheter is inserted into the abdominal aorta (Seldinger method). Aorto‐ nephrography is performed as the first step of the procedure (Fig.1 - A). This is followed by selective catheterisation of renal arteries and contrast agent (usually Omnipac) is applied us‐ ing an automatic syringe (Fig. 1 - B). Image of arterial and venous intermediate is obtained

**•** Increased flow through the renal artery and the resulting expansion of the arteries,

**•** Presence of pathological vascularization in arterial phase (numerous, tortuous vessels

**•** Nephrograms with the image of tumorous discoloration occuring due to retention of con‐

This is followed by injecting the embolizing material through a vascular catheter. Most frequently used is Spongostan which is fragmented and placed at the end of a syringe filled with 0.9% NaCl, and then injected into renal artery. Spongostan embolization often supplemented with different coils. In case of confirmation in renal arteriography of tu‐ mor vascularization by more than one artery, respectively all the supplying vessels are

The whole procedure of RAE (Fig. 1 A – D) lasts about 30 – 60 minutes and its effectiveness (lack of blood flow in renal vessels) is confirmed in angiography after re-injection of contrast

with angiographic confirmation of following RC characteristics:

with impaired angioarchitectonics)

**•** Loss of saturable renal parenchyma.

medium through the catheter withdrawn to the aorta.

trast in blood vessels,

embolized, as above.

zation syndrome [1].

98 Renal Tumor

potential benefits.

**Figure 1.** Stages of vascular embolization of renal artery. A. arteriography; B. vascularization of renal tumour; C. mate‐ rial for embolization injected to renal artery; D. closed renal artery.

After completing the RAE procedure the femoral artery puncture site is deemed temporary with pressure dressing. Few hours after RAE standard blood tests, monitoring of urine out‐ put and assessment of severity of postembolization symptoms (lumbar pain - a symptom that occurs in nearly all patients after effective RAE, nausea, vomiting, fever, transient renal failure and symptoms of gastrointestinal paralytic ileus). Medication (analgesic, antispas‐ modic, prokinetic agents, anticoagulants drugs and antibiotics) are prescribed appropriately to symptoms and depending on the clinical situation. In the study group of 474 patients there were no clinically significant complications (death, femoral hematoma, migration of embolizing material or ischemic spinal cord injury) [1,14].

Time schedules of RAE and nephrectomy are not established precisely, usually RAE is made few – several days before nephrectomy. In some cases RAE is made one only day before sur‐ gery to avoid acute postembolization syndrome.