Kinase inhibitors for cancer alter metabolism, blood glucose, and insulin

Small molecule kinase inhibitors (SMKIs) are a class of therapeutic drugs that target protein kinases in diseases such as cancer. SMKIs are often designed to inhibit kinases involved in cell proliferation, but these drugs alter cell metabolism and the endocrine control of organismal metabolism. SMKI treatment in diabetic cancer patients reveals that certain SMKIs improve blood glucose levels and can mitigate insulin dependence or diabetic medication requirements in both type 1 diabetes (T1D) and type 2 diabetes (T2D). Certain SMKIs can preserve functional β-cell mass and increase insulin secretion or insulin sensitivity. It is not yet clear why different SMKIs can have opposing effects on insulin and blood glucose. Understanding the therapeutic effects of these drugs in T1D and T2D is complicated by overlapping off-target effects of SMKIs. The potency of inhibition of the intended protein kinase and inhibition of multiple off-target kinases may underpin conflicting reports of how certain SMKIs alter blood glucose and insulin. We summarize the effects of SMKIs on the intended and off-target kinases that can alter blood glucose and insulin, including c-Abl, c-Kit, EGFR, and VEGF. Inhibition of PDGFRβ consistently lowers blood glucose in T1D and T2D. The effects of SMKIs on the kinases that regulate immune pathways, such as BTK and RIPKs, mediate many of the diverse effects of these drugs on metabolism. We highlight that inhibition of RIPK2 by SMKIs is a central node in metabolism that influences key metabolic pathways including lipolysis, blood glucose control, insulin secretion, and insulin resistance.

Postbiotics engage IRF4 in adipocytes to promote sex-dependent changes in blood glucose during obesity

Postbiotics are microbial-derived components or metabolites that can influence host immunity and metabolism. Some postbiotics can improve blood glucose control and lower inflammation during bacterial or nutritional stress. Bacterial cell wall-derived muramyl dipeptide (MDP) is a potent insulin-sensitizing postbiotic that engages NOD2, RIPK2, and requires interferon regulatory factor 4 (IRF4) to lower inflammation and improve blood glucose. However, the sex-dependent effects of this postbiotic and the cell type required for IRF4 to cause inflammatory versus glycemic responses to MDP were unknown. Here, we measured how MDP injection altered glucose tolerance and adipose tissue inflammation during low-level endotoxemia and high fat diet (HFD)-induced obesity in male and female adipocyte-specific IRF4 knockout mice (AdipoIRF4fl/fl ) compared to WTfl/fl mice. Adipocyte IRF4 was required for the blood glucose-lowering effects of MDP during endotoxemia and HFD-induced obesity in male mice. However, MDP did not alter blood glucose in female WTfl/fl and AdipoIRF4fl/f mice during endotoxemia. Unexpectedly, female HFD-fed AdipoIRF4fl/f mice had lower blood glucose after MDP treatment compared to WTfl/fl mice. MDP lowered inflammatory gene expression in adipose tissue of HFD-fed WTfl/fl and AdipoIRF4fl/fl mice of both sexes. Therefore, MDP-mediated lowering of adipose inflammation does not require adipocyte IRF4 and was independent of sex. Together, these data show that injection of MDP, an insulin-sensitizing postbiotic, lowers adipose tissue inflammation in male and female mice, but lower adipose inflammation is not always associated with improved blood glucose. The blood glucose-lowering effect of the postbiotic MDP and dependence on adipocyte IRF4 is sex-dependent.

Micronutrients impact the gut microbiota and blood glucose

Micronutrients influence hormone action and host metabolism. Dietary minerals, trace elements, and vitamins can alter blood glucose and cellular glucose metabolism, and several micronutrients are associated with the risk and progression of type 2 diabetes. Dietary components, microbes, and host immune, endocrine, and metabolic responses all interact in the intestine. There has been a focus on macronutrients modifying the host-microbe relationship in metabolic disease. Micronutrients are positioned to alter host-microbe symbiosis that participates in host endocrine control of glucose metabolism. Minerals and trace elements can alter the composition of the intestinal microbiota, gut barrier function, compartmentalized metabolic inflammation, cellular glucose transport, and endocrine control of glucose metabolism, including insulin and thyroid hormones. Dietary vitamins also influence the composition of the intestinal microbiota and vitamins can be biotransformed by gut microbes. Host-microbe regulation of vitamins can alter immunity, lipid and glucose metabolism, and cell fate and function of pancreatic beta cells. Causal effects of micronutrients in host-microbe metabolism are still emerging, and the mechanisms linking dietary excess or deficiency of specific micronutrients to changes in gut microbes directly linked to metabolic disease risk are not yet clear. Dietary fiber, fat, protein, and carbohydrates are key dietary factors that impact how microbes participate in host glucose metabolism. It is possible that micronutrient and microbiota-derived factors also participate in host-microbe responses that tip the balance in the endocrine control of host glucose metabolism. Dietary micronutrients should be considered, tested, and controlled in pre-clinical and clinical studies investigating host-microbe factors in metabolic diseases.

The effect of pharmacologically altered gastric pH on cadmium absorption from the diet and its accumulation in murine tissues

Solubility of Cd in Cd-amended mouse chow in water was reduced by increased pH; even less Cd was solubilized by simulated digestion in vitro, where increased gastric phase pH decreased solubility, an effect that persisted following intestinal digestion at pH 5.5. These data suggested that increasing gastric pH in vivo pharmacologically would reduce Cd accumulation in target organs of mice treated with omeprazole (a proton-pump inhibitor) or cimetidine (a H2-receptor antagonist). This expectation was mostly not realized. Gastric pH in animals receiving Cd-amended diet was increased by omeprazole, but not cimetidine, relative to animals receiving no drugs, and Cd-amended diet. Tissue concentrations of Cd were similar among the three groups receiving Cd-amended diet, for liver, kidney and testes. Small intestine Cd concentration was lower for omeprazole-treated animals than for those receiving neither drug and Cd-amended diet, suggesting that omeprazole decreased Cd absorption by this organ. This effect may have been compensated for by increased uptake of complexed Cd by the large intestine, as accumulation in the liver, kidney and testes was not reduced. In vitro determinations of bioaccessible Cd in food may not predict in vivo bioaccumulation in all target organs.

Differential accumulation of Cd in durum wheat cultivars: uptake and retranslocation as sources of variation

Durum wheat (Triticum turgidum L. var. durum) accumulates Cd from the soil depending on various factors. When grown in hydroponic solution containing Cd (20 microg l(-1)), roots had higher tissue Cd concentrations than shoots or heads. Kyle (the higher grain-Cd accumulating cultivar) had lower root-Cd, and greater shoot-Cd and head-Cd concentrations than Arcola (the lower grain-Cd accumulating cultivar). These cultivar differences were greater at flowering and ripening than at tillering. Much of the root-Cd was lost between the flowering and ripening stages of development. Distribution of (106)Cd among plant parts, after a single 24 h feeding, demonstrated that root-to-shoot transfer of Cd in Arcola was similar to that of Kyle at tillering, but it had ceased at flowering in Arcola but not Kyle. None of the Cd in wheat heads at ripening originated from (106)Cd exposure in the previous 24 h, suggesting that grain-Cd is a function of total shoot accumulation. Both cultivars demonstrated basipetal translocation of Cd; Arcola at tillering translocated more Cd from shoots to roots than Kyle. The proportion of Cd(2+)/Cd(total) in the nutrient solution decreased with time, suggesting that plant activity altered the solution chemistry. The alteration probably resulted from either preferential depletion of solution Cd(2+) and/or addition of root exudates. Lower grain-Cd accumulation in Arcola possibly resulted from a combination of reduced root-to-shoot transfer of Cd at flowering, as well as enhanced shoot-to-root retranslocation of Cd, at least in younger plants. Plant-mediated changes in solution-Cd speciation did not play a role.

Accumulation of dietary cadmium (Cd) in rabbit tissues and excretions: a comparison of lettuce amended with soluble Cd salt and lettuce with plant-incorporated Cd

Quantifying the transfer of Cd from foods to mammalian target organs is key to estimating the health risk from this exposure; however, the bioaccumulation of Cd from foods is modified by many dietary components. Studies of dietary Cd absorption would be simpler if it were known that Cd added to foods as a soluble salt was as bioavailable as Cd incorporated during growth of the food species. Rabbits were fed, for 16 d, fresh lettuce containing cadmium incorporated into the lettuce during growth or added to the lettuce before feeding, or lettuce with no Cd but soluble Cd administered to the animals by gavage. There was a marked positive relationship between increased Cd dose and its accumulation in kidney; the slopes for the gavage and added treatments were not clearly different from the incorporated treatment; liver data were highly variable. In a 10-wk study of Cd-incorporated and -amended lettuce diets, for the incorporated and control diets there was less Cd accumulation in the kidneys, but not liver, per unit cumulative dose, than for the amended diet. Cd accumulation in the small intestine and Cd concentration in feces, both per unit daily dose, were smaller for the incorporated than for the control and amended diets; Cd concentrations in bile, urine, and serum, per unit daily dose, were higher in the control diet than values in the amended diet, which were higher than the incorporated diet. These differences could not be accounted for by variation in Fe or Zn contents of the diets. Thus, data suggest that Cd-amended diets overestimate bioaccumulation in kidney, an important target organ, by up to one-third, and that studies of short duration are not adequate to evaluate Cd bioavailability from food.

Does increased needle biopsy sampling of the prostate detect a higher number of potentially insignificant tumors?

PURPOSE

Several studies have documented that increased biopsy sampling, that is 6 versus 12 biopsy cores, can detect more prostate cancer. It is unknown whether increased sampling of the prostate will detect a higher number of potentially insignificant tumors.

MATERIALS AND METHODS

We searched the surgical pathology files at The Johns Hopkins Hospital for patients in whom prostate needle biopsy was performed by a single urologist between April 1993 and April 2000, and subsequently underwent radical prostatectomy. Patients who underwent radical prostatectomy and had 8 core biopsies or less between March 1994 and August 1999 were also studied. Clinically significant tumors were defined as those with volume greater than 0.5 cc, Gleason score 7 or greater or nonorgan confined disease.

RESULTS

A total of 297 patients with a mean age of 60 years (range 36 to 75) were evaluated. Group 1 consisted of 107 men with 8 core biopsies or less, including 51 with 6, and group 2 comprised 190 men with 9 cores or greater, including 145 with 12. The 2 groups were equal in regard to prostate specific antigen, age, digital rectal examination and transrectal ultrasound gland volume at biopsy. The only difference between the groups was a higher number of cores with cancer in group 2 (mean 2.8 versus 2.1, p = 0.0006). Of the patients who underwent radical prostatectomy 59.6% had Gleason score 6 or less, 26.3% 3+4, 6.7% 4+3 and 7.4% 8 to 9. There were 12.4% of patients with positive margins, 36.4% extraprostatic extension, and 5.4% seminal vesicle invasion and/or lymph node metastasis. Tumor volumes averaged 1.1 cc (range 0.01 to 10.7) and 60.9% of tumors were greater than 0.5 cc. Clinically significant tumors were seen in 77.4% of patients in group 1 and 74.6% in group 2. There was no significant difference in Gleason score, margin status, tumor volume, seminal vesicle invasion, or lymph node metastasis between groups 1 and 2, or in a subset analysis of men with 6 versus 12 core biopsies. However, patients in whom cancer was diagnosed with 9 core biopsies or greater were more likely to have organ confined disease (p = 0.02).

CONCLUSIONS

Although increased sampling of the prostate does not increase the detection of potentially insignificant tumors, it does appear to detect earlier stage cancer.

Laparoscopic radical nephrectomy: cancer control for renal cell carcinoma

PURPOSE

We evaluated the clinical efficacy of laparoscopic versus open radical nephrectomy in patients with clinically localized renal cell carcinoma.

MATERIALS AND METHODS

Between 1991 and 1999, 67 laparoscopic radical nephrectomies were performed for clinically localized, stages cT1/2 NXMX, pathologically confirmed renal cell carcinoma. During this period 54 patients who underwent open radical nephrectomy with pathologically confirmed stages pT1/2 NXMX disease were also identified. Medical and operative records were retrospectively reviewed and telephone followup was done to assess patient status.

RESULTS

In the laparoscopic and open groups average tumor size was 5.1 (range 1 to 13) and 5.4 cm. (range 0.2 to 18), respectively, which was not statistically significant. No patient had laparoscopic port site, wound or renal fossa tumor recurrence in either group. All patients were followed at least 12 months. In the laparoscopic group 2 cancer specific deaths occurred at a mean followup of 35.6 months. In the open group there were 2 cancer specific deaths and 3 cases of disease progression at a mean followup of 44 months. Kaplan-Meier disease-free survival and actuarial survival analysis revealed no significant differences in the laparoscopic and open radical nephrectomy groups. Also, no differences were noted in the complication rate.

CONCLUSIONS

Laparoscopic radical nephrectomy is an effective alternative for localized renal cell carcinoma when the principles of surgical oncology are maintained. Initial data show shorter patient hospitalization and effective cancer control with no significant difference in survival compared with open radical nephrectomy.

Does capsular incision at radical retropubic prostatectomy affect disease-free survival in otherwise organ-confined prostate cancer?

OBJECTIVES

To evaluate the influence of isolated, histologically identified capsular incision (CI) (exposure of benign or malignant glands to the inked surgical margin in the setting of organ-confined disease) on disease progression after anatomic radical retropubic prostatectomy (RRP) for clinically localized prostate cancer.

METHODS

Between March 1993 and September 1999, 4747 men underwent RRP at the Johns Hopkins Hospital; 107 men (2.3%) were diagnosed with CI in otherwise organ-confined disease; 92 (86%) had at least 6 months (mean 30) of follow-up. We matched these CI cases (based on surgeon, age, clinical stage, final pathologic Gleason grade, and preoperative serum prostate-specific antigen level) one-for-one with controls in three additional pathologically defined groups and compared the freedom from disease progression (prostate-specific antigen level greater than 0.2 ng/mL and/or local palpable recurrence) after RRP.

RESULTS

The actuarial 3-year likelihood of freedom from disease progression was 87.8% for the CI group, 96.4% for men with organ-confined disease (P = 0.10), 91.3% for men with extraprostatic extension and negative surgical margins (P = 0.99), and 73.9% for men with positive surgical margins resulting from extraprostatic extension (P <0.01). No statistically significant difference was found in the actuarial likelihood of freedom from disease progression between men with CI into benign glands (n = 22) and men with CI into tumor (n = 70) (P = 0.93).

CONCLUSIONS

No statistically significant difference was found in the likelihood of early recurrence between patients with isolated CI and other specimen-confined disease. Patients with isolated CI have a significantly lower likelihood of early recurrence than patients with positive surgical margins due to extraprostatic extension, regardless of whether the CI is into benign glands or tumor. Long-term follow-up is necessary to confirm these findings.

Interaortocaval renal artery dissection for right laparoscopic donor nephrectomy

Laparoscopic donor nephrectomy is gaining increasing popularity because the procedure helps reduce disincentives to live kidney donation and has increased the live kidney donor pool. The left kidney of the donor is the preferred allograft because the right renal vein is shorter. Similarly, the right renal artery might be foreshortened because it hides behind the inferior vena cava during laparoscopic transperitoneal dissection. There are instances, however, in which it is not practical to take the left kidney due to vascular anomalies or asymmetric function. We describe a novel technique for obtaining greater renal arterial length utilizing laparoscopic interaortocaval dissection.

Density functional theory of charged colloidal systems

The phase behavior of charged colloidal systems has been studied recently by the density functional theory formalism (DFT) [R. van Roij, M. Dijkstra, and J. P. Hansen, Phys. Rev. E 59, 2010 (1999)]. A key feature of this approach is the appearance of a density and temperature-dependent effective Hamiltonian between the charged colloids. Under certain approximations, the effective Hamiltonian is made up only of a sum of position-independent one-body or volume terms and two-body colloid-separation dependent terms. In the limit of low colloidal densities, the DFT results do not reduce to the familiar Debye-Hückel limiting law nor do the results agree with previous work based on an identical approach but were developed using traditional statistical-mechanical methods [B. Beresford-Smith, D. Y. C. Chan, and D. J. Mitchell J. Colloid Interface Sci. 105, 216 (1985)]. This paper provides a reconciliation of these differences and comments on the significance of the one-body volume terms in the effective Hamiltonian of a system of charged colloids in determining thermodynamics and phase behavior.

Determinants of continence in the bladder exstrophy population: predictors of success?

OBJECTIVES

To delineate factors that may predict eventual urinary continence after bladder neck reconstruction (BNR) in the bladder exstrophy population.

METHODS

The records of 65 patients who underwent all phases of bladder exstrophy reconstruction at our institution between 1975 and 1997 with greater than 1-year follow-up were reviewed and data analyzed.

RESULTS

Fifty patients (77%) are continent day and night and voiding per urethra without need for augmentation or intermittent catheterization. Nine (14%) patients have social continence, dry for more than 3 hours during the day. Two patients required continent diversion for continence after failed BNR. Four patients are completely incontinent. The mean age of BNR was 4 years with a mean and median capacity of 93 and 85 cc (range 45 to 175). Analysis of bladder capacity measurements prior to BNR revealed that patients with a bladder capacity greater than 85 cc median capacity at the time of BNR had better outcomes. No correlation was found between the age of BNR and obtaining eventual continence. The mean time to daytime continence was 14 months (range 4 to 21) and the mean time to nighttime continence was 22 months (range 11 to 33).

CONCLUSIONS

Determinants of continence in the bladder exstrophy population are multifactorial. In our experience, 77% of patients are completely dry, day and night, and 91% can achieve social continence, being dry for at least 3 hours. However, with careful evaluation of bladder capacity and bladder growth, urinary continence may be improved in this population with better patient selection.

Laparoscopic nephroureterectomy for the treatment of transitional cell carcinoma of the upper urinary tract

OBJECTIVES

To establish the safety and efficacy of laparoscopic and laparoscopic-assisted nephroureterectomy.

METHODS

Since 1993, 25 patients with a minimum of 12 months of follow-up underwent nephroureterectomy using a total laparoscopic or laparoscopic-assisted technique. Four patients had specimen morcellation for tissue removal. All patients had regular follow-up with physical examinations, interval cystoscopy, and radiographs, depending on the metastatic potential of the tumor. Retrospective chart review was performed and assessed for operative time, blood loss, tumor pathologic stage, complications, and outcome. One patient was excluded because of an open conversion due to multiple previous abdominal surgeries and failure to progress.

RESULTS

The mean operating time was 329 minutes but decreased with experience. The median hospital stay was 4 days. Tumor stage was directly related to tumor grade. Associated bladder tumors (prior history or recurrent tumors) occurred in 50% of the patients. Ipsilateral ureteral stump site recurrence occurred in 1 patient. Although no port site seeding occurred, 1 patient, whose tumor was discovered histologically after laparoscopic pyeloplasty for presumed benign disease, developed recurrence in the renal fossa and metastatic disease. Two patients developed liver metastasis.

CONCLUSIONS

Total laparoscopic and laparoscopic-assisted nephroureterectomy are acceptable alternatives to open surgery in the treatment of transitional cell carcinoma of the upper urinary tract. Tumor morcellation did not appear to adversely affect patient outcome. As with open nephroureterectomy, tumor grade is the most important prognostic indicator of local, bladder, and metastatic recurrence. No port site seeding was observed in either the total laparoscopic or laparoscopic-assisted groups.

Image-guided therapy in urology

Technological breakthroughs have advanced the fields of urology, radiology, and minimally invasive surgery. Today, the various imaging modalities are increasingly applied to guiding therapy. Among the procedures now in use or under development are percutaneous cyst drainage or sclerotherapy; tissue ablation with high-intensity focused ultrasound, cold, heat, or photon radiation; and conformal radiation and brachytherapy. As current limitations are overcome, image-guided therapy will expand.

Rapid ligation of renal hilum during transperitoneal laparoscopic nephrectomy

We describe our surgical technique for rapid ligation of the renal hilum during transperitoneal laparoscopic nephrectomy. This technique is reliable and provides an efficient method of hilar ligation.

Temporal CT changes after hepatic and renal interstitial radiotherapy in a canine model

PURPOSE

The purpose of this work was to define the temporal CT characteristics of hepatic and renal ablation following point-source radioablation utilizing a low energy, photon X-ray source emitted from a miniature probe.

METHOD

Twelve mongrel dogs underwent each of three hepatic and two renal point-source radiation ablations. Animals underwent serial, dual phase, spiral CT scans and were killed at 1, 3, and 6 months after treatment.

RESULTS

Ablative lesions were clearly visible at 1 month following therapy and consistently diminished in size over the 6 months of follow-up. Lesion size tended to be proportional to dose delivered. Both hepatic and renal lesions were low in attenuation with frequent rim enhancement that diminished over time. Hepatic lesions frequently showed transient hepatic attenuation differences (THADs). Lesion size appeared independent of proximity to vessels.

CONCLUSION

Following hepatic or renal interstitial radiotherapy, lesions are generated that are similar in CT appearance to those produced by other ablative techniques. The presence of rim or THAD enhancement can be seen early on as part of the normal tissue-healing response.

Focal hepatic ablation using interstitial photon radiation energy

BACKGROUND

Intratumoral ablative therapy is being used increasingly for the treatment of primary and secondary hepatic malignancies. The interstitial point-source photon radiosurgery system (PRS) is a novel ablative technique that uses radiation therapy similar in dosimetry to interstitial brachytherapy.

STUDY DESIGN

To determine the feasibility, toxicity, and local tissue destructive capabilities of the PRS in the liver, preliminary studies in a nontumor-bearing canine model were examined. A 6-month survival study was conducted. Each animal received three radiation treatments, in the right, central, and left hepatic regions. Three low-dose treatments were delivered to each of six animals (group A), generating a 2.0-cm-diameter radiated sphere with a dose of 20 Gy at the lesion edge. Three high-dose treatments were delivered to each of six animals (group B), generating a 3.0-cm-diameter radiated sphere with 20 Gy at the lesion edge.

RESULTS

The treatment reproducibly generated sharply demarcated hepatic ablative lesions proportional to the administered dose. Mean lesion diameter at 1 month was 1.6+/-0.2 cm in group A and 3.4+/-1.0 cm in group B. Lesion size was independent of intrahepatic location, including near vascular structures. PRS therapy, when applied to portal structures, resulted in hilar damage. Hilar damage appeared to be associated with arteriolar thrombosis and bile duct injury. Treatment of regions adjacent to large hepatic veins and the IVC was not associated with vessel thrombosis or stricture.

CONCLUSIONS

PRS ablation is a generally well-tolerated method that results in consistent, well-demarcated, symmetric lesions of complete necrosis with minimal adjacent parenchymal injury. Application of such an approach for the treatment of liver tumors is promising.

Extensively necrotic cystic renal cell carcinoma: a clinicopathologic study with comparison to other cystic and necrotic renal cancers

Renal cell carcinomas often show varying degrees of necrosis and cystic change. The prognostic importance of necrosis so extensive that only a few tumor cells can be identified is not clear. We gathered clinicopathologic and follow-up data on a group of eight such cases ("type I"). These patients were compared with two other groups of renal cell carcinomas: those with extensive necrosis (>50%), yet with readily identifiable tumor ("type II"), and cancers with extensive cystic change not resulting from necrosis, usually multiloculated ("type III"). The groups showed similar demographic characteristics, and within each group there was great variation in tumor size. Conventional (clear cell) histology was more common than papillary morphology in all groups. The type II neoplasms tended to be of higher nuclear grade and pathologic stage than the other groups. While one of six type I patients with follow up progressed 131 months after diagnosis, eight of 20 type II patients showed progression. None of the six type III patients with follow up progressed. We conclude that renal cell carcinomas showing extensive necrosis are capable of aggressive behavior, and patients with these lesions cannot be assured of cure following surgery. Pathologists must be aware of this entity and extensively sample any renal lesion showing extensive necrosis. The tumors showing a greater amount of viable neoplastic cells yet at least 50% necrosis had a higher rate of progression than did the type I patients. The lack of progression of any of the type III cases supports the idea that type III multiloculated cystic renal cell carcinomas may carry a distinctly better prognosis than other forms of renal cell carcinoma.

Mini-percutaneous nephrolithotomy

Standard percutaneous nephrolithotomy is highly effective for the removal of renal calculi. However, significant morbidity has been associated with this procedure. Consequently, many urologists inappropriately defer to a less effective procedure to reduce patient morbidity. This practice may increase the total number of procedures needed for treatment and result in a substantial increase in health care costs. Mini-percutaneous nephrolithotomy using a 13F ureteroscopy sheath is described to reduce the morbidity associated with standard percutaneous nephrolithotomy while maintaining its efficiency and effectiveness for stone removal. The indications and technique for mini-percutaneous nephrolithotomy and our results are summarized.

Effect of time delay on surgical performance during telesurgical manipulation

BACKGROUND

Telementoring allows a less experienced surgeon to benefit from an expert surgical consultation, reducing cost, travel, and the learning curve associated with new procedures. However, there are several technical limitations that affect practical applications. One potentially serious problem is the time delay that occurs any time data are transferred across long distances. To date, the effect of time delay on surgical performance has not been studied.

MATERIALS AND METHODS

A two-phase trial was designed to examine the effect of time delay on surgical performance. In the first phase, a series of tasks was performed, and the numbers of robotic movements required for completion was counted. Programmed incremental time delays were made in audiovisual acquisition and robotic controls. The number of errors made while performing each task at various time delay intervals was noted. In the second phase, a remote surgeon in Baltimore performed the tasks 9000 miles away in Singapore. The number of errors made was recorded.

RESULTS

As the time delay increased, the number of operator errors increased. The accuracy needed to perform remote robotic procedures was diminished as the time delay increased. A learning curve did exist for each task, but as the time delay interval increased, it took longer to complete the task.

CONCLUSIONS

Time delay does affect surgical performance. There is an acceptable delay of <700 msec in which surgeons can compensate for this phenomenon. Clinical studies will be needed to evaluate the true impact of time delay.

Feasibility of ablating normal renal parenchyma by interstitial photon radiation energy: study in a canine model

BACKGROUND AND PURPOSE

A miniature photon radiosurgery system (PRS) has been described as an alternative to surgical resection and external-beam radiation for tumors and may now offer an alternative for ablation of renal lesions. We evaluated the feasibility of ablation by PRS in a normal parenchyma canine model.

MATERIALS AND METHODS

Twelve mongrel dogs were used in this survival study. In the left and right kidneys of each animal, a peripheral lesion and central-hilar lesion, respectively, were induced with PRS. The probes were placed in the renal parenchyma, and local radiation of 15 Gy at a radius of 1.3 cm was delivered over 10 minutes. Serum electrolytes were measured serially. Computed tomography scans were obtained, and the animals were sacrificed for pathologic correlation. In a separate study, the liver received three additional treatments of 10 to 20 minutes of radiation.

RESULTS

Eleven dogs survived this 6-month study and were sacrificed as scheduled. One animal expired after 2 weeks from radiation-induced fulminant hepatic failure with normal renal function. No other complications were observed. The average lesion size was 2.5 cm in diameter. Histologic analysis confirmed coagulative necrosis with sharp demarcation from the surrounding parenchyma.

CONCLUSION

Preliminary studies demonstrate the feasibility of PRS ablation of the renal parenchyma. Further tumor model testing will be important to determine the ultimate efficacy of local photon radiation energy.

Renal ablative cryosurgery in selected patients with peripheral renal masses

OBJECTIVES

To present the preliminary results of renal ablative cryosurgery in selected patients.

METHODS

Seven patients were treated, all of whom had small peripheral tumors and chose not to undergo partial or radical nephrectomy. Four patients underwent a rib-sparing flank incision; the remaining three underwent laparoscopy. All tumors were biopsied before cryoablation. Intraoperative ultrasound was used to monitor the cryolesion.

RESULTS

There were no intraoperative complications. The estimated blood loss averaged 111 mL. To date, 6 of the 7 patients have undergone at least one follow-up computed tomography scan (14.2 months average follow-up); all these scans demonstrated partial resolution of the lesion. Clinically, the patients tolerated the procedure without any renal complications or significant changes in creatinine.

CONCLUSIONS

This limited clinical trial has demonstrated the feasibility of treating small peripherally located renal tumors with cryosurgery with minimal morbidity and a favorable outcome. Further studies are necessary to determine the long-term efficacy of this treatment modality.

Laparoscopic nephrectomy for autotransplantation

Proximal ureteral injuries often require extensive reconstruction to repair. Management options include nephrectomy, ileal ureter interposition, extensive spiral bladder flaps, or autotransplantation. We report a patient who sustained a proximal ureteral avulsion and underwent a less invasive repair by way of a laparoscopic nephrectomy and subsequent autotransplantation.

Partial nephrectomy for centrally located tumors

INTRODUCTION

Interest in nephron-sparing surgery has been spurred by the good long-term results of patients treated with partial nephrectomy. Partial nephrectomy entails the complete resection of renal tumor while leaving behind clear surgical margins and maximum functional renal parenchyma.

TECHNICAL CONSIDERATIONS

We prefer to access the renal tumor by a flank incision. Intraoperative sonography is used to define the operative lesion and to search for multicentric tumors. A vascular clamp is placed on the renal hilum for vascular control. Regional hypothermia protects the kidney during renal ischemia. The perinephric fat is excised in situ with the renal tumor. Tumor base biopsies ensure negative margins. Meticulous dissection and tying of vessels improves hemostasis. Diluted methylene blue is directly injected into the renal pelvis to inspect for any intrarenal leakage. The argon beam coagulator is used routinely, and collagen (Avitene) is placed into the renal defect for hemostasis. The renal parenchyma and Gerota's fascia are reapproximated anatomically. A small drain is left in place, and the wound is closed in the usual manner.

CONCLUSIONS

Recent studies continue to report that conservative surgery is as effective as radical nephrectomy for renal cell carcinoma, but the judgments in patient selection and operative management are paramount in determining its success.

Electrical Double-Layer Interaction between Charged Particles near Surfaces and in Confined Geometries

The proximity effect of one or two flat surfaces on the double-layer interaction between two identically charged colloidal particles immersed in an electrolyte is examined. Simple analytical formulas are presented for the interaction of (i) two particles in the vicinity of a charged flat surface and (ii) two particles confined between two parallel plates. It is found that the surface(s) can strongly influence the pairwise interaction of the particles, leading to increase, decrease, or even elimination of the electrostatic interaction, in comparison to the corresponding result in an unbounded electrolyte. Copyright 1999 Academic Press.

Retroperitoneal access for transperitoneal laparoscopy in patients at high risk for intra-abdominal scarring

BACKGROUND AND PURPOSE

Adhesions from prior extensive open abdominal surgery can make initial transperitoneal access for laparoscopy hazardous. An alternative to open port placement is a retroperitoneal approach to the peritoneal cavity. We describe our retroperitoneal access for transperitoneal laparoscopy and evaluate the success of the subsequent laparoscopic procedure.

PATIENTS AND METHODS

Eight patients with a history of abdominal surgery have undergone retroperitoneal access to the peritoneum prior to a laparoscopic urologic procedure. With the patient in a lateral decubitus position, the retroperitoneum is entered with a 10-mm Visiport device (US Surgical Corp., Norwalk, CT) along the posterior axillary line. A working space is bluntly created, the peritoneum identified anterior to the colon, and the endoscope passed through a peritoneotomy. The abdomen is then inspected, transperitoneal ports are strategically placed under direct vision, and the intended procedure is commenced.

RESULTS

In all cases, retroperitoneal access to the peritoneum and subsequent trocar placement was successful. In five cases, the intended procedure was completed laparoscopically. In a case of bilateral ureterolysis, one side was completed laparoscopically; however, the other required open conversion. In two nephrectomies for xanthogranulomatous pyelonephritis (XGP), open conversion was necessary because of fibrosis.

CONCLUSION

Retroperitoneal access to the peritoneal cavity permits safe and effective port placement when previous abdominal surgery makes initial transabdominal access difficult. However, despite successful access, in patients at risk for extensive perinephric fibrosis (e.g., XGP), a high incidence of open conversion may be expected.

Laparoscopic testicular denervation for chronic orchalgia

PURPOSE

No specific cause is identified in most cases of chronic orchialgia. Nonsurgical therapies, including management at a chronic pain clinic, are generally recommended. Only when multiple conservative measures fail are patients offered surgical intervention, such as orchiectomy. We evaluate laparoscopic testicular denervation as an organ preserving and minimally invasive surgical alternative.

MATERIALS AND METHODS

Since 1993, 9 patients with chronic orchialgia have undergone transperitoneal laparoscopic testicular denervation after nonsurgical modalities failed. Using 1, 10 mm. and 1 or 2, 5 mm. ports, the gonadal vessels were isolated circumferentially and divided cephalad to the vas deferens and its vasculature. Preoperative treatment modalities, morbidity and outcome were documented. A cord block provided temporary relief in all 9 patients. Analog scales were used to assess long-term pain relief (0 no pain to 100 worst pain) and activity levels (0 bedrest to 100 no restrictions).

RESULTS

Average symptom duration before laparoscopic testicular denervation was 4.1 years. Of 9 patients 8 had undergone prior scrotal surgery. Failed nonsurgical modalities included anti-inflammatory drugs in 7 patients, antibiotics in 6, pain clinic consultations in 4 and antidepressant medications in 2. Mean pain score decreased from 69.4 (range 35 to 90) preoperatively to 30.6 at a mean followup of 25.1 months. Excluding the 2 cases that had no pain relief (less than 10-point reduction), average pain score decreased from 69 to 19 postoperatively (mean reduction 71%). Activity levels improved in all cases. There were no significant complications, including testis atrophy. One patient who had no pain relief underwent subsequent hydrocelectomy for pain, which also failed.

CONCLUSIONS

Laparoscopic testicular denervation can provide significant long-term pain relief and appears to be a reasonable alternative in select cases with chronic orchialgia refractory to medical therapy. Larger series and prospective evaluations are necessary.

Long-Range Electrostatic Attractions between Identically Charged Particles in Confined Geometries: An Unresolved Problem

Long-range electrostatic attractions between identical colloidal particles in confined geometries have been observed experimentally by many workers. A satisfactory theoretical explanation for this behavior has proven elusive. Recent numerical calculations and reports (Nature 393, 621-623, 663-665 (1998)), however, have suggested that this problem is closed by demonstrating that this surprising effect is to be found naturally within the well-established Poisson-Boltzmann (PB) theory. We rigorously prove that these claims are false; within the framework of the PB theory, the interaction between identical colloidal particles is always repulsive, irrespective of whether the particles are isolated or confined. A satisfactory theoretical explanation of this surprising phenomenon thus remains an unresolved problem. Copyright 1999 Academic Press.

Laparoscopic renal cryoablation: acute and long-term clinical, radiographic, and pathologic effects in an animal model and application in a clinical trial

OBJECTIVES

To evaluate renal cryosurgery by studying the feasibility of laparoscopic delivery and the radiographic characteristics and histopathologic effects in a porcine model using different freeze cycles. On the basis of the results, a clinical trial of laparoscopic cryosurgical ablation in select patients with clinical stage T1 renal tumors was started.

MATERIALS AND METHODS

Twelve kidneys from six farm pigs underwent cryosurgery. Each kidney was treated with two freeze cycles to -180 degrees C. Six kidneys were retroperitonealized, and six were not. An abdominal CT scan was performed at various times to evaluate for the presence of urinoma or hematoma and to monitor lesion changes. Organs were harvested at times ranging from 24 hours to 13 weeks. Radiographic and histopathologic changes were recorded for each time period. Eight patients with small (average 2-cm) exophytic renal masses underwent laparoscopic biopsy and cryosurgical ablation using a 3- or 4.8-mm probe (Cryomedical Sciences Inc., Rockville, MD) for one 15-minute or two 5-minute freeze cycles to a temperature of -180 degrees C to extend the ice ball at least 7 mm beyond the tumor margin.

RESULTS

Dense adhesions between the bowel and cryoablated renal tissue were encountered in all non-retroperitonealized kidneys, but no fistula formation was present. The retroperitonealized kidneys had minimal adhesion formation. None of the animals developed a urinary fistula. At 24 hours and 1 week, CT scanning demonstrated an enhancement defect corresponding to the region of the ice ball with no urinoma or hematoma. At 13 weeks, only a nonenhancing cortical defect was seen. At immediate harvest, hemorrhage was noted in the area of the ice ball with a sharp demarcation at the edge of the freeze zone. At 1 week, four distinct zones were seen: central necrosis, inflammatory infiltrate, hemorrhage, and fibrosis with regeneration. At 13 weeks, the necrotic tissue had been replaced with a circumscribed area of fibrosis. There were no intraoperative or postoperative complications in the eight patients. The estimated blood loss was 140 mL, and the mean hospital stay was 3.5 days. At a mean clinical follow-up of 7.7 (range 1-18) months and radiographic follow-up of 5 months; there have been no tumor recurrences or significant changes in the serum creatinine concentration. At 24 hours, there was an enhancement defect in the area of the ice ball. The CT images at 13 weeks showed a nonenhancing cortical defect in the area of the ice ball.

CONCLUSIONS

Cryosurgery can be readily delivered laparoscopically, creating a discrete lesion at the time of treatment that appears to be consistent over time. In the animal studies, complete tissue necrosis developed in the freeze zone, followed by reabsorption, and by 13 weeks, fibrous tissue had replaced the defect. In the animal and human trials, there were no operative complications, urinomas, hematomas, or bowel or urinary fistulas. Follow-up imaging in human trials revealed a persistent nonenhancing defect in the area of the freeze zone. Long-term clinical follow-up will be necessary to determine the cancer-free survival rate.

Laparoscopic donor nephrectomy: standard of care or unnecessary risk of organ loss?

Laparoscopic donor nephrectomy was developed to remove disincentives to live donation. It has been demonstrated to decrease the length of hospitalization, postoperative pain, time to convalescence and activity, while providing an optimal cosmetic result. Initial reports suggest that laparoscopic donor nephrectomy is feasible and equivalent to open donor nephrectomy.

Surgery in advanced and metastatic renal cell carcinoma

Curative surgery in more advanced renal cell carcinoma is limited to solitary metastases or regional disease. Response to systemic immunotherapy continues to be reported; however, most responses are limited and not durable. Only randomized, prospective clinical trials will prove the efficacy of systemic therapy.

Analysis of Inhomogeneous Optical Systems by the Use of Ray Tracing. II. Three-dimensional Systems with Symmetry

We describe a new approach to the index reconstruction of three-dimensional optical systems with rotational symmetry, which is based on sampling ray paths that lie in the sagittal plane. Since the observed rays are distorted by the optical system itself, they cannot be used directly for index reconstruction. We present an iterative procedure to compute the true ray paths and then to find the index distribution. The utility of the method is verified on the model problem.

Analysis of inhomogeneous optical systems by the use of ray tracing. I. Planar systems

We describe a novel approach to refractive-index reconstruction in two-dimensional systems with no special symmetry, based on observation of traces of rays that travel through the optical system. The mathematical model of ray-tracing analysis is presented in detail, and both the analytical and numerical solutions are given. Methods of data processing in the presence of experimental errors are developed and applied to model problems.

Refractive index gradient of human lenses

We report nondestructive measurements and the modeling of the refractive index profiles in human lenses. Results in the equatorial and sagittal planes are compared with destructive measurements of refractive index, modeled data as well as with microdensitometric measurements of protein concentration. These comparisons highlight the differences between current models and measured data on human lenses.

Nondestructive method of constructing three-dimensional gradient index models for crystalline lenses: I. Theory and experiment

A nondestructive method of constructing the three-dimensional refractive index profile of crystalline lenses is presented. The technique is based on earlier work in which the refractive index profile is deduced from measuring the refraction of a set of light rays that traverse the lens in a particular plane. However, the present approach requires fewer assumptions about the form of the refractive index profile so that the deduced results are less likely to reflect preconceived notions about the form of the refractive index distribution. An accurate model for the bovine crystalline lens has been constructed with the present approach. Without further adjustable parameters, our three-dimensional model of the lens refractive index profile is able to predict accurately the refraction of meridional rays that traverse the lens in the sagittal plane. Preliminary data on human lenses are also presented.

Determination and modeling of the 3-D gradient refractive indices in crystalline lenses

A simple method of constructing 3-D gradient refractive-index profiles in crystalline lenses is proposed. The input data are derived from 2-D refraction measurements of rays in the equatorial plane of the lens. In this paper, the isoindicial contours within the lens are modeled as a family of concentric ellipses; however, other physically more appropriate models may also be constructed. This method is illustrated by using it to model the 3-D refractive-index profile of a bovine lens.

The Smoluchowski-Poisson-Boltzmann description of ion diffusion at charged interfaces

A theoretical description of ion diffusion in the electric field set up by the double layer in the neighborhood of a charged interface is presented. Such a description is needed for the understanding of diffusion-controlled chemical kinetics and transport of ionic species in a variety of systems of interest in biophysics, electrochemistry, and colloid science. The ion dynamics are taken to be governed by the Smoluchowski diffusion equation and the average electrostatic field is obtained from the nonlinear Poisson-Boltzmann equation. Diffusion in finite regions with partially absorbing boundaries of planar, cylindrical, or spherical geometry is considered. The complete analytical solution of the Smoluchowski-Poisson-Boltzmann equation for counterions between two planar charged interfaces is given. Simple expressions are derived for certain useful integral quantities, viz., mean absorption times and absorption probabilities, in all geometries considered. Finally, lateral counterion diffusion and its consequences for surface re-encounter-enhanced chemoreception is considered.

Evidence for variation in the number of functional gene copies at the AmaR locus in Chinese hamster cell lines

The hypothesis of functional hemizygosity has been examined for the alpha-amanitin resistant (AmaR, a codominant marker) locus in a series of Chinese hamster cell lines. AmaR mutants were obtained from different cell lines, e.g., CHO, DHW, M3- 1 and CHO-Kl, at similar frequencies. After fractionation of different RNA polymerase activities in the extracts by chromatographic procedures, the sensitivity of the mutant RNA polymerase II towards alpha-amanitin was determined. While all of the RNA polymerase II activity in mutant CHO and CHO-Kl lines became resistant to alpha-amanitin inhibition, only about 50% of the activity is highly resistant in AmaR mutants of CHW and M3- 1 cell lines. The remaining activity in the latter cell lines shows alpha-amanitin sensitivity similar to that seen with the wild-type enzyme. This behaviour is similar to that observed with a 1:1 mixture of resistant and sensitive enzymes from CHO cells. These results, therefore, strongly indicate that while only one functional copy of the gene affected by alpha-amanitin is present in CHO and CHO-Kl cells, two copies of this gene are functional in the CHW and M3-1 cell lines.

Cellular retinol- and retinoic acid-binding proteins in transformed mammalian cells

Extracts prepared from several lines of transformed cells were examined for the presence of cellular binding proteins specific for retinoids. Extracts of human retinoblastoma cell line WERI-Rb1 contained a cellular binding protein specific for retinoic acid, whereas extracts of human retinoblastoma cell line Y-79 contained cellular binding proteins for both retinol and retinoic acid. Upon purification, the latter two binding proteins proved to have properties similar to those of the corresponding proteins obtained from bovine retina. Smaller amounts of these binding proteins were detected in extracts of undifferentiated and differentiated neuroblastoma and McCoy cells. HeLa and rat glioma cells had no detectable amount of binding proteins. The 11-cis-retinal-binding protein, present in extracts of human, rat, and bovine retina, was not found in any of the cell lines examined.