Rectification properties of carbon nanotube "Y-junctions"

Quantum conductivity of single-wall carbon nanotube Y-junctions is calculated. The current versus voltage characteristics of these junctions show asymmetry and rectification, in agreement with recent experimental results. Furthermore, rectification is found to be independent of the angle between the branches of these junctions, indicating this to be an intrinsic property of symmetric Y-junctions. The implications for the Y-junction to function as a nanoscale molecular electronic switch are investigated.

Robotically assisted laparoscopic radical prostatectomy: feasibility study in men

PURPOSE

We report our early experience of robotically assisted laparoscopic radical prostatectomy.

MATERIAL AND METHODS

Five consecutive patients, with an average age of 58 years, PSA 12, 1.6 positive biopsies, Gleason score 6, were operated in our institution over a period of 1 week by the same surgeon. A robotically assisted laparoscopic nerve sparing radical prostatectomy was performed according to the Montsouris technique with the Da Vinci robot (Intuitive Inc., Mountain View, Calif., USA).

RESULTS

The mean installation time was 93 min (range 76-149). The mean operating time (starting at the dissection of the seminal vesicles until the final stitch of the anastomosis) was 222 min (range 150-381 min). The average blood loss was 800 cm(3) (range 700-1,600 cm(3)). No postoperative complications were seen. Bladder catheter time: 6.5 days, hospital stay 5.5 days, urine leak 1/5, continence 4/5, positive margin 1/5.

CONCLUSION

After this short experience, we conclude that: The use of a tele manipulation system accompanied by a three-dimensional view of the operating field provides a real benefit for the surgeon, and the urethro-anastomosis is easier to perform. The benefit for the patient is presently not very clear in terms of operating time, postoperative course and functional results, our initial results show that the robotically assisted procedure is at least as safe and effective as the conventional laparoscopic procedure.

The gonadotropin-releasing hormone antagonist abarelix depot versus luteinizing hormone releasing hormone agonists leuprolide or goserelin: initial results of endocrinological and biochemical efficacies in patients with prostate cancer

PURPOSE

We contrasted the endocrinological and biochemical efficacies of abarelix depot, a pure gonadotropin-releasing hormone antagonist, with a prospective concurrent control cohort receiving luteinizing hormone releasing hormone (LH-RH) agonists with or without antiandrogen for treatment of patients with prostate cancer receiving initial hormonal therapy.

MATERIALS AND METHODS

In this phase 2 open label study 242 patients with prostate cancer requiring initial hormonal treatment received abarelix depot (209) or LH-RH agonists (33) with or without antiandrogen. A total of 100 mg. abarelix depot was delivered intramuscularly every 28 days with an additional injection on day 15. LH-RH agonists with or without antiandrogen were administered according to the depot formulation used. Endocrine efficacy was measured by the absence of testosterone surge and rapidity of castration onset. The rate of prostate specific antigen decrease was assessed.

RESULTS

No patient treated with abarelix depot had testosterone surge during week 1 compared with 82% of those treated with LH-RH agonists. The concomitant administration of antiandrogen had no effect. During the first week of drug administration, in 75% of patients treated with abarelix depot and in 0% of those treated with LH-RH agonist medical castration was achieved. Prostate specific antigen decrease was faster, with no flare or surge in patients treated with abarelix depot. Abarelix depot was well tolerated.

CONCLUSIONS

Abarelix depot represents a new class of hormonal therapy, gonadotropin releasing hormone antagonists, that has rapid medical castration and avoids the testosterone surge characteristic of LH-RH agonists.

Role of substance P in several models of bladder inflammation

Substance P (SP) is a peptide found in the sensory nervous system which has multiple biologic effects including stimulation of muscle contraction, pain nociception, immune cell functions, plasma extravasation and a constellation of inflammatory effects. Here we investigate the role of SP in several animals models of bladder inflammation. Using the female Lewis rat, inflammation was induced using either xylene, lipopolysaccharide (LPS) or polyinosinic-polycytidylic acid (polyIC). Inflammation occurred rapidly (4 h) and was maintained in each model for at least 7 days. Each of these protocols decreased the bladder content of immunoreactive SP by approximately 50%, suggesting enhanced release. There was no change in the urinary frequency of these animals over 3 weeks, suggesting that urinary frequency changes are not mediated by acute inflammation. We also found that the SP receptor (NK1) antagonist, (-)CP96345, was unable to block the inflammation produced by polyIC, suggesting that SP is not an obligatory mediator of immune cell stimulation in this model.

Ginger: an ethnomedical, chemical and pharmacological review

Powerful medicinal properties have been recorded for Zingiber officinale, commonly known as ginger. All of these medicinal activities have been compiled with 99 references to the present status of the plant in the literature. Volatile components and the presence of trace metals are included. In addition, details of individual medicinal activities are given and the molecular structures of identified organic metabolites and their synthesis are described.

Catalytic action of Ni atoms in the formation of carbon nanotubes: a molecular dynamics study

Catalytic action of Ni atoms in the growth of single-wall carbon nanotubes is investigated using tight-binding molecular dynamics and ab initio methods. Our results demonstrate this to be a two step process in which the Ni atom first creates and stabilizes defects in nanotubes. The subsequent incorporation of incoming carbon atoms anneals the Ni-stabilized defects freeing the Ni atom to repeat the catalytic process.

When and how to evaluate a patient with nephrolithiasis

Nephrolithiasis is a common disorder that afflicts up to 12% of the population and continues to be a significant cause of patient injury. Evaluation of these patients should include the assessment of their comorbidities and underlying medical conditions. Patients who form stones can undergo a streamlined evaluation. A cause can be found in more than 90% of these patients. With medical treatment, stone-recurrence rates can be decreased by 85% for calcium oxalate stone formation, which affects a large proportion of patients. Introduction of nonspecific medical therapy in uncomplicated calcium stone disease may improve the quality of life for these patients and allow utilization a simple diagnostic protocol. This is in contrast to the previous recommendations of disease-specific therapy. Because patients without complications represent the majority of those who form stones, a simplified approach greatly reduces the cost of evaluation and treatment. Underlying medical conditions, however, require disease-specific therapy. The protocol represented here should aid physicians and patients in the approach to management of stone disease. The fasting calcium-load test is not required, and the entire evaluation can be performed in an ambulatory setting in two visits. Two 24-hour urine samples should be obtained on a random and restricted diet. Patients who form calcium stones can be subdivided into those who form hypercalciuric and normocalciuric stones. Patients who form normocalciuric stones are treated with conservative measures (increased fluid intake) and potassium and magnesium citrate. Patients who form hypercalciuric stones are treated with a combination of thiazides and potassium and magnesium citrate.

Chemistry of the rhenium-azopyridine family: an oxo parent and derivatives thereof including a novel oxo-imido dimer

The concerned azo ligands are 2-(phenylazo)pyridine (HL) and 2-((p-chlorophenyl)azo)pyridine (ClL). The reaction of KReO4 with HL in hot concentrated HCl is attended with metal reduction and ligand chlorination affording the oxo complex ReVOCl3(ClL), 2, which furnishes ReIII(OPPh3)Cl3(ClL), 3, upon treatment with PPh3. Aromatic amines, ArNH2, convert 2 to the imido complex ReV(NAr)Cl3(ClL), 5, and the unusual oxo-imido dimer (ClL)-Cl2(O)ReVOReV(NAr)Cl2(ClL), 7. The complex ReIII(OPPh3)Cl3(HL), 4, has been generated from ReVOCl3(PPh3)2 and HL. Reaction of 4 with HL has yielded ReV(NPh)Cl3(HL), 6, via azo splitting. The complexes have been characterized with the help spectral, magnetic, and X-ray structural data (2, 3, 5c (Ar = pClC6H4) and 7.CH2Cl2 (Ar = pMeC6H4)). In 2, 3, and 5c the ReCl3 fragment is meridionally disposed, and in 7 the ReCl2 fragments have a trans configuration. The Re-O(oxo) bond, 1.663(6) A, in 2 and Re-N(imido) bond, 1.719(5) A, in 5c are triple bonds. The corresponding bonds are slightly longer in 7 wherein the (O)Re(1)-O(2)-Re(2)(NAr) bridge is angular (151.0(5) degrees) and unsymmetrical, the Re(1)-O(2) bond, 1.849(7) A, having a large double-bond character (Re(2)-O(2), 1.954(7) A). In effect, cis-ReVO2 acts as a monodentate oxygen ligand toward ReVNAr in 7. In all cases the pyridine nitrogen binds trans to the oxo, OPPh3, or NAr donor. Bond length data are consistent with the presence of substantial d(Re)-pi*(azo) back-bonding. In acetonitrile solution the complexes display electrochemical one-electron metal (ReVI/ReV or ReIV/ReIII) and azo redox. The imido ligand in 5 stabilizes the ReVI state (E1/2 approximately 1.4 V) better than the oxo ligand in 2 (approximately 1.9 V). Parallely it is more difficult to reduce the azo group in 5 (approximately -0.4 V) than in 2 (approximately 0.0 V). In 7 the metal (approximately 1.0 V) and azo (approximately -0.4 V) couples correspond to the imido and oxo halves, respectively. The significantly higher (by 0.2-0.6 V) metal reduction potentials of the azopyridine compared to pyridine-2-aldimine complexes is ascribed to the superior pi-acidity and electron-withdrawing character of the azo function relative to the aldimine function. This also makes the transfer of the ReVO oxygen function much more facile under azopyridine chelation as in 2. For the same reason, ReOCl3(PPh3)2 reacts with HL affording only 4 while it reacts with pyridine-2-aldimines furnishing oxo species. Crystal data for the complexes are as follows: 2, empirical formula C11H8Cl4N3ORe, crystal system triclinic, space group P1, a = 7.118(4) A, b = 8.537(4) A, c = 13.231(9) A, alpha = 79.16(5) degrees, beta = 78.03(5) degrees, gamma = 70.96(4) degrees, V = 737.2(7) A3, Z = 2; 3, empirical formula C29H23Cl4N3OPRe, crystal system monoclinic, space group P2(1)/n, a = 11.264(2) A, b = 15.221(3) A, c = 17.628(4) A, beta = 94.21(3) degrees, V = 3014(1) A3, Z = 4; 5c, empirical formula C17H12Cl5N4Re, crystal system triclinic, space group P1, a = 9.683(3) A, b = 10.898(3) A, c = 11.522(3) A, alpha = 63.67(2) degrees, beta = 71.24(2) degrees, gamma = 86.79(2) degrees, V = 1026(1) A3, Z = 2; 7.CH2Cl2, empirical formula C30H25Cl8N7O2Re2, crystal system triclinic, space group P1, a = 12.522(6) A, b = 12.857(8) A, c = 13.182(7) A, alpha = 67.75(4) degrees, beta = 88.30(4) degrees, gamma = 82.09(4) degrees, V = 1945(2) A3, Z = 2.

Equilibrium Shapes of Solid Particles on Elastically Mismatched Substrates

Small particles or islands bonded to a substrate can be profoundly influenced by both interfacial and elastic driving forces that tend to have opposing influences on the apparent wetting behavior. The superposition of these two driving forces can therefore lead to a rich set of particle properties, most notably their equilibrium shapes. Here we present a variational analysis leading directly to an Euler-Lagrange equation that can be solved to yield the equilibrium shapes of partially wetting particles as a function of their size, interface energy densities, and elastic interaction with a rigid substrate. The solutions are used to gain insight into the variables that most significantly influence the equilibrium morphology, and to derive the approximate driving force for surface area reduction by coarsening among a dispersion of unequally sized particles. The relatively simple analytical model can also form a foundation upon which more realistic numerical simulations may be built and compared. Copyright 1999 Academic Press.

Oxalate: from crystal formation to crystal retention

Idiopathic calcium oxalate stone formation is a multifactorial disease. It is therefore unlikely that a single underlying condition will be responsible for entire spectrum of the disease; however, it appears that one important factor in the pathogenesis is an abnormality in oxalate metabolism. Whatever the cause, two critical parameters for stone formation are crystal formation and crystal retention in the renal tubules. Although crystal formination and role of oxalate in crystal formation have been evaluated extensively, it is only recently that crystal retention has been addressed. Previous studies from our laboratories demonstrated that oxalate exposure to renal epithelial cells in culture resulted in initiation of a program of events including DNA synthesis and cell death. The present studies evaluated effects of oxalate on cell proliferation and damage to distal tubular (Madin-Darby canine kidney cells) and proximal (LLC-PK1 cells) cells. Effects of oxalate exposure on calcium oxalate monohydrate (COM) crystal adherence to these cells were also evaluated. Results presented herein demonstrate that proximal tubular cells are more sensitive to oxalate than distal tubular cells. Furthermore, oxalate exposure to proximal tubular cells resulted in reinitiation of DNA synthesis, whereas no such effect was observed in distal tubular cells. Higher levels of oxalate (> 1 mM) resulted in cell loss of both proximal and distal tubular cells, as observed by crystal violet staining. Despite these differences, oxalate exposure to both proximal and distal tubular cells resulted in increased COM crystal adherence. Thus, oxalate exposure may promote crystal adherence to renal epithelial cells either secondarily to cell death and proliferation or by a yet unidentified mechanism. These studies provide the first direct evidence for the role of oxalate in promoting COM crystal retention by the urothelium.

Prognostic significance of the 1997 TNM classification of renal cell carcinoma

PURPOSE

The TNM classification of renal cell carcinoma was recently revised in 1997. The most significant change from the previous edition (1987) is an increase in the size cutoff between T1 and T2 tumors from 2.5 to 7.0 cm. We compared the 1997 and 1987 TNM staging classifications in predicting patient outcome.

MATERIALS AND METHODS

A total of 381 patients who underwent nephrectomy for renal cell carcinoma at our hospital between 1968 and 1994 were identified. Mean patient age was 61 years (range 15 to 89) and mean followup was 64.5 months. All pathological slides were re-reviewed in uniform manner and staged using the 1987 and 1997 TNM classifications. The impact of numerous pathological factors and each staging classification on disease specific survival and freedom from progression were statistically analyzed, and Kaplan-Meier survival curves were generated and compared.

RESULTS

The 1997 TNM classification resulted in a redistribution of 170 cases previously classified as stage II (T2N0M0) to stage I (T1N0M0) under the new system. Both classifications were strong predictors of survival on univariate and multivariate analyses, and essentially equivalent in the ability to predict patient outcome. However, comparison of survival curves on Kaplan-Meier life tables revealed better separation of survival for stage I (T1N0M0) and stage II (T2N0M0) cases under the 1997 TNM classification, with survival for TNM stage I essentially remaining unchanged.

CONCLUSIONS

The 1997 TNM classification of renal cell carcinoma appears to be equivalent to the previous classification in predicting outcome but permits better stratification of cases according to survival and, therefore, may have improved clinical usefulness.

Community physicians who provide terminal care

BACKGROUND

Most dying patients are treated by physicians in community practice, yet studies of terminal care rarely include these physicians.

OBJECTIVE

To examine the frequency of life-sustaining treatment use and describe what factors influence physicians' treatment decisions in community-based practices.

METHODS

Family members and treating physicians for decedents 65 years and older who died of cancer, congestive heart failure, chronic lung disease, cirrhosis, or stroke completed interviews about end-of-life care in community settings.

RESULTS

Eighty percent of eligible family and 68.8% of eligible physicians participated (N = 165). Most physicians were trained in primary care and 85.4% were primary care physicians for the decedents. Physicians typically knew the decedent a year or more (68.9%), and 93.3% treated them for at least 1 month before death. In their last month of life, 2.4% of decedents received cardiopulmonary resuscitation, 5.5% received ventilatory support, and 34.1% received hospice care. Family recalled a discussion of treatment options in 78.2% of deaths. Most discussions (72.1%) took place a month or more before death. Place of death, cancer, and having a living will were independent predictors of less aggressive treatment before death. Physicians believed that advanced planning and good relationships were the major determinants of good decision making.

CONCLUSIONS

Community physicians use few life-sustaining treatments for dying patients. Treatment decisions are made in the context of long-term primary care relationships, and living wills influence treatment decisions. The choice to remain in community settings with a familiar physician may influence the dying experience.

Cost comparison of orchiectomy and leuprolide in metastatic prostate cancer

PURPOSE

We objectively compare the costs associated with the medical and surgical treatment of metastatic prostate cancer.

MATERIALS AND METHODS

We analyzed and compared itemized billing statements for 28 men with metastatic adenocarcinoma of the prostate. Half of the men were treated medically with the luteinizing hormone-releasing hormone analogue leuprolide, while the other half underwent bilateral therapeutic orchiectomy. In addition, differences in hospital cost to treat these men were calculated.

RESULTS

During a mean followup of 24 months leuprolide treated patients were charged $500.00 per month of treatment compared to average monthly expenditure of $226.00 for orchiectomy patients during a 23-month interval. By 9 months charges incurred by both groups were equal and by 20 months medically treated patients accumulated urological charges twice that of the surgically treated patients. The true hospital cost to treat these patients followed the same trend, that is the medically treated group cost twice as much to treat by 15 months. For the average stage D2 case leuprolide therapy charges were $9,420, or 63%, more than orchiectomy. Similarly, leuprolide cost the hospital $8,924 more than surgery.

CONCLUSIONS

Medical management of metastatic prostate cancer is expensive. With broadening applications and androgen deprivation being initiated earlier in the course of disease, the amount spent on medical therapy will continue to escalate. For patients with a life expectancy of more than 9 months orchiectomy is the most cost-effective treatment option.

Effect of vitamin C on androgen independent prostate cancer cells (PC3 and Mat-Ly-Lu) in vitro: involvement of reactive oxygen species-effect on cell number, viability and DNA synthesis

Studies have described the protective role of vitamin C (ascorbic acid) in certain types of cancer. In this study, we report the effects of vitamin C treatment of two androgen independent prostate cancer cell lines from human (PC3) and rat (Mat-Ly-Lu or MLL) sources. In vitro treatment of PC3 and MLL with sodium ascorbate acid (0-10 mM) resulted in a decrease in cell viability and thymidine incorporation into DNA. These effects of vit. C were dose and time dependent. Ascorbate induced these changes through the production of hydrogen peroxide since addition of catalase (100-300 units/ml), an enzyme that degrades hydrogen peroxide, inhibited the effects of ascorbate on these cell lines. In contrast, superoxide dismutase, an enzyme that dismutates superoxide and generates hydrogen peroxide did not prevent ascorbate-induced changes emphasizing the involvement of reactive oxygen species (ROS) in cellular damage. That singlet oxygen scavengers such as sodium azide and hydroquinone, hydroxyl radical scavengers such as D-mannitol and DL-alpha-tocopherol did not counteract the effects of ascorbate on thymidine incorporation suggests that these free radicals are not involved in cellular damage. In conclusion, these results suggest that vitamin C inhibits tumor growth by virtue of producing reactive oxygen species. These results suggest that ascorbate is a potent anticancer agent for prostate cancer cells.

Antiproliferative effects of c-myc antisense oligonucleotide in prostate cancer cells: a novel therapy in prostate cancer

OBJECTIVES

To explore the possibility of using antisense oligonucleotide therapy for prostate cancer, we investigated the effect of c-myc-antisense-oligonucleotide (c-myc-As-ODN) in human prostate cancer cell lines such as LNCaP, PC3, and DU145.

METHODS

LNCaP, PC3, and DU145 cells were incubated in the presence of c-myc-As-ODN. Dose (0 to 10 microM) and time dependent (1 to 6 days) effects on proliferation and viability were examined by [3H]thymidine incorporation and MTT assay, respectively. Flow cytometry analysis was carried out to analyze cell cycle status by determining the DNA content in LNCaP cells. Control cultures received either c-myc-sense-ODN or scrambled (nonsense) nucleotides.

RESULTS

Time- and dose-dependent decreases in DNA synthesis and cell viability were noted for all three prostate cancer cell lines after c-myc-As-ODN treatment. Further studies using LNCaP cells indicated that these changes were accompanied by an increase in the percentage of cells with less than 2N DNA content after c-myc-As-ODN treatment. The results suggest that c-myc-As-ODN induces cell death. Comparison of a c-myc-As-ODN-treated group with a group subjected to isoleucine deprivation revealed that thymidine incorporation was almost the same in c-myc-As-ODN-treated LNCaP cells and in LNCaP cells at early S phase.

CONCLUSIONS

These results suggest that c-myc-As-ODN inhibits prostate cancer cell growth and proliferation mainly by decreasing cell viability.