Quasi-static and dynamic properties of the intervertebral disc: experimental study and model parameter determination for the porcine lumbar motion segment.

PURPOSE: The study of axial loading is essential to determine the properties of intervertebral disc. The objectives of this work are (1) to quantify the mechanical properties of porcine lumbar intervertebral discs under static and cyclic compressive loading, and (2) to determine the parameters of a five-parameter rheological model for porcine and compare them with those obtained for human lumbar intervertebral discs. METHODS: Thus, the porcine lumbar motion segments were subjected to quasi-static and dynamic compression tests. The quasi-static tests were used to obtain the static stiffness coefficient at different strain rates, while the data from the cyclic compressive tests were used to both determine the dynamic stiffness coefficient and to be fitted in a 5-parameter model, in order to simulate the creep response of the porcine intervertebral discs. RESULTS: The results demonstrated that dynamic stiffness coefficient of porcine discs is between four and ten times higher than the static stiffness coefficient, depending on load applied. The parameters of the rheological model suggested a low permeability of nucleus and endplate during the fast response of porcine discs. In addition, the fast response in terms of displacement is four times higher than those documented for human discs. CONCLUSIONS: This study revealed that care must be taken on the comparison between porcine and human discs, since they present different behaviour under quasi-static and dynamic compressive loading.

Long-Term Creep Behavior of the Intervertebral Disk: Comparison between Bioreactor Data and Numerical Results.

The loaded disk culture system is an intervertebral disk (IVD)-oriented bioreactor developed by the VU Medical Center (VUmc, Amsterdam, The Netherlands), which has the capacity of maintaining up to 12 IVDs in culture, for approximately 3 weeks after extraction. Using this system, eight goat IVDs were provided with the essential nutrients and submitted to compression tests without losing their biomechanical and physiological properties, for 22 days. Based on previous reports (Paul et al., 2012, 2013; Detiger et al., 2013), four of these IVDs were kept in physiological condition (control) and the other four were previously injected with chondroitinase ABC (CABC), in order to promote degenerative disk disease (DDD). The loading profile intercalated 16 h of activity loading with 8 h of loading recovery to express the standard circadian variations. The displacement behavior of these eight IVDs along the first 2 days of the experiment was numerically reproduced, using an IVD osmo-poro-hyper-viscoelastic and fiber-reinforced finite element (FE) model. The simulations were run on a custom FE solver (Castro et al., 2014). The analysis of the experimental results allowed concluding that the effect of the CABC injection was only significant in two of the four IVDs. The four control IVDs showed no signs of degeneration, as expected. In what concerns to the numerical simulations, the IVD FE model was able to reproduce the generic behavior of the two groups of goat IVDs (control and injected). However, some discrepancies were still noticed on the comparison between the injected IVDs and the numerical simulations, namely on the recovery periods. This may be justified by the complexity of the pathways for DDD, associated with the multiplicity of physiological responses to each direct or indirect stimulus. Nevertheless, one could conclude that ligaments, muscles, and IVD covering membranes could be added to the FE model, in order to improve its accuracy and properly describe the recovery periods.

Effects of cyanobacterial extracts containing anatoxin-a and of pure anatoxin-a on early developmental stages of carp.

This study compares the effects of pure anatoxin-a and cyanobacterial extracts of an anatoxin-a producing strain on early stages of development of carp. Carp eggs were exposed from 2:30 h to 4 days post-fertilization to different ecologically relevant concentrations of anatoxin-a, provided as pure toxin or contained in the cyanobacterial extracts. Data on time to mortality, mortality rate, time to hatching, hatching rate, skeletal malformations rate, and larval standard length were registered until 8 days post-fertilization. At any tested concentration of anatoxin-a, the pure toxin was almost harmless to carp early stages of development, contrarily to cell extracts that were highly toxic. Only an adverse effect on the larval length was found at the highest concentration of pure toxin, while increasing concentrations of cell extracts caused increasing adverse effects in all the analyzed parameters. Anatoxin-a producing cyanobacteria should be regarded as putative modulators of aquatic ecosystems communities.

Efficacy and safety of flexible-dose oral sildenafil citrate (Viagra) in the treatment of erectile dysfunction in Brazilian and Mexican men.

A 12-week, double-blind, placebo-controlled, multicenter study evaluated the efficacy and safety of flexible-dose sildenafil citrate (Viagra) treatment (25, 50 or 100 mg) in Brazilian and Mexican men with erectile dysfunction (ED) of broad-spectrum etiology. Efficacy was assessed on the basis of responses to the 15-item International Index of Erectile Function (IIEF) questionnaire, completed at baseline and after 12 weeks of treatment. At end point, mean scores for all IIEF domains of sexual function (erectile function, orgasmic function, sexual desire, intercourse satisfaction and overall satisfaction) were significantly (P<0.0001) higher in the sildenafil group (n=109) than in the placebo group (n=105). These findings confirm the significant increases in frequency of penetration and frequency of maintained erections reported previously. Sildenafil treatment was well tolerated. The most common adverse events were headache and flushing. In conclusion, sildenafil is a well-tolerated and effective treatment for ED of broad-spectrum etiology in Latin American men.

Intracavernous injection in the treatment of erectile dysfunction after radical prostatectomy: an observational study.

CONTEXT: Despite the recent improvements in performing radical retropubic prostatectomy that have led to a considerable decrease in the complication rate, erectile dysfunction still represents a major problem. Moreover, less invasive treatment options that are emerging for erectile dysfunction have not shown satisfactory results in managing these patients. OBJECTIVE: To study the efficacy and side effects of self-injection therapy in the treatment of men who had become impotent after undergoing radical prostatectomy due to prostate cancer, over a study period of 96 months. DESIGN: Observational study. SETTING: University Referral Center. PARTICIPANTS: 168 patients with erectile dysfunction, aged 43 to 78 years old, who underwent radical retropubic prostatectomy due to localized prostate cancer. PROCEDURES: The patients were treated with self-injection therapy using papaverine, phentolamine and prostaglandin E1, at home. RESULTS: This study showed an acceptable 94.6% success rate, with no life-threatening complications. In addition to this, our series presented a 13.1% cure rate with this therapy. CONCLUSION: Self-injection therapy with papaverine, phentolamine and prostaglandin E1 is effective and safe in the treatment of erectile dysfunction after radical prostatectomy.

(AC)23 [Z-2] polymorphism of the aldose reductase gene and fast progression of retinopathy in Chilean type 2 diabetics.

A recent case-control study suggests that the allele (AC)23 of a variable number tandem repeat (VNTR) associated to the aldose reductase (ALR2) gene could be related to early retinopathy in Type 2 diabetics. By means of a longitudinal-retrospective study, we aimed to seek for a relationship between the rate of progression of retinopathy and the (AC)23 allele of the VNTR associated to the ALR2 gene. A random sample was obtained of 27 Type 2 diabetics (aged 68.1 +/- 10.6 years, diabetes duration = 20.7 +/- 4.8 years, mean HbA1 = 10.6 +/- 1.6%). The mean HbA1 was the arithmetic average of 2.2 measurements per patient per year of total glycosilated hemoglobin (Gabbay method, normal range: 4.2-7.5%). Retinopathy was graded by an Ophthalmologist in a scale from zero to four score points. The genotype of the (AC), VNTR was determined by 32P-PCR plus sequenciation in a Perkin-Elmer laser device. The Mann-Whitney test and either chi2 or Fisher's exact test were used. A P < 0.05 was considered as statistically significant. The retinopathy progression rate (RPR, points x year(-1)) was calculated by dividing the increment of retinopathy score (delta Retinopathy Score, [points]), by the duration of the follow up [years]. The 12 diabetics having the (AC)23 allele had a mean RPR 8.9 times higher (0.40 +/- 0.61 points x year(-1)) than the 15 patients who had alleles other than (AC)23 (0.045 +/- 0.099 points x year(-1), P = 0.037). Both groups were similar with respect to: mean HbA1 (10.5 +/- 1.4 and 10.7 +/- 1.7%, P = 0.95), age at diagnosis (48.5 +/- 6.3 and 46.3 +/- 14.0 years, P = 0.81), diabetes' duration (21.3 +/- 4.7 and 20.2 +/- 4.9 years, P = 0.41) and serum creatinine (0.89 +/- 0.2 and 1.13 +/- 0.5 mg dl(-1), P = 0.35). We concluded that, in Type-2 diabetics having similar glycemic control, the (AC)23 allele of the VNTR associated to the ALR2 gene, is associated to a 8.9 times faster progression of retinopathy than in patients who have other alleles.

[Aldose reductase gene polymorphism and rate of appearance of retinopathy in non insulin dependent diabetics]. / Polimorfismo del gen de aldosa reductasa y velocidad de aparición de retinopatía en diabéticos no insulinodependientes.

BACKGROUND: Recent studies suggest that polymorphisms associated to the aldose reductase gene could be related to early retinopathy in noninsulin dependent diabetics (NIDDM). There is also new interest on the genetic modulation of coagulation factors in relation to this complication. AIM: To look for a possible relationship between the rate of appearance of retinopathy and the genotype of (AC)n polymorphic marker associated to aldose reductase gene. PATIENTS AND METHODS: A random sample of 27 NIDDM, aged 68.1 +/- 10.6 years, with a mean diabetes duration of 20.7 +/- 4.8 years and a mean glycosilated hemoglobin of 10.6 +/- 1.6%, was studied. The genotype of the (AC)n, polymorphic marker associated to the 5' end of the aldose reductase (ALR2) gene was determined by 32P-PCR plus sequenciation. Mutations of the factor XIII-A gene were studied by single stranded conformational polymorphism, sequenciation and restriction fragment length polymorphism. RESULTS: Four patients lacked the (AC)24 and had a higher rate of appearance of retinopathy than patients with the (AC)24 allele (0.0167 and 0.0907 score points per year respectively, p = 0.047). Both groups had similar glycosilated hemoglobin (11.7 +/- 0.2 and 10.5 +/- 1.6% respectively). Factor XIII gene mutations were not related to the rate of appearance of retinopathy. CONCLUSIONS: Our data suggest that the absence of the (AC)24 allele of the (AC)n polymorphic marker associated to the 5' end of the aldose reductase gene, is associated to a five fold reduction of retinopathy appearance rate.

Cavernosometria de gravedad versus cavernosometria de bomba en la difuncion erectil veno-oclusiva / Gravity versus pump cavernosometry in the veno-oclusive dysfunction

Todavía hay muchas controversias relacionadas con laevaluación de la disfuncion eréctil veno-oclusiva. Aunque la cavernosometría ha sido considerada el método de elección para este diagnóstico, el mejor procedimiento para tal fin permanece en discución. Para comparar los valores de la cavernosometría por gravedad y por bomba en el diagnóstico de la fuga venosa, evaluamos 42 pacientes, 12 voluntarios con función eréctil normal y 30 con disfunción eréctil. Estos pacientes fueron asignados a dosd grupos distintos. Un grupo fue evaluado mediante la cavernosometría de bomba seguida por la cavernosometría de gravedad (o gravimétrica); en el otro grupo los procedimientos fueron invertidos. El valor promedio de la presión de infusión durante la cavernosometría de gravedad fue de 111,5 cm H2O (con una variación de 100 a 120 cm H2O). Considerando los pacientes con una presión de infusión de 100 cm H2O o más alta que lo normal, hemos tenido una concordancia del 100 por ciento entre ambas cavernosometrías, sin importar cuál fue hecha primero. La cavernosometría de gravedad es un método sencillo y simple, con una buena relación costo-beneficio para el diagnóstico de la disfunción eréctil veno-oclusiva(AU)

Cavernosometria de gravedad versus cavernosometria de bomba en la difuncion erectil veno-oclusiva / Gravity versus pump cavernosometry in the veno-oclusive dysfunction

Todavía hay muchas controversias relacionadas con laevaluación de la disfuncion eréctil veno-oclusiva. Aunque la cavernosometría ha sido considerada el método de elección para este diagnóstico, el mejor procedimiento para tal fin permanece en discución. Para comparar los valores de la cavernosometría por gravedad y por bomba en el diagnóstico de la fuga venosa, evaluamos 42 pacientes, 12 voluntarios con función eréctil normal y 30 con disfunción eréctil. Estos pacientes fueron asignados a dosd grupos distintos. Un grupo fue evaluado mediante la cavernosometría de bomba seguida por la cavernosometría de gravedad (o gravimétrica); en el otro grupo los procedimientos fueron invertidos. El valor promedio de la presión de infusión durante la cavernosometría de gravedad fue de 111,5 cm H2O (con una variación de 100 a 120 cm H2O). Considerando los pacientes con una presión de infusión de 100 cm H2O o más alta que lo normal, hemos tenido una concordancia del 100 por ciento entre ambas cavernosometrías, sin importar cuál fue hecha primero. La cavernosometría de gravedad es un método sencillo y simple, con una buena relación costo-beneficio para el diagnóstico de la disfunción eréctil veno-oclusiva

Ureteroscopic stone removal in the distal ureter. Why change?

PURPOSE: We compared our experience with ureteroscopic stone basket manipulation under fluoroscopic guidance to ultrasound ureterolithotripsy for distal ureteral stone removal. MATERIALS AND METHODS: Retrospectively, we analyzed the medical records of 981 patients with ureteral calculi between January 1994 and December 1995, of whom 483 (49%) were treated for stones in the lower ureter and constituted our study group. The decision of when to perform lithotripsy (group 2) versus a basket procedure (group 1) was based on a prospective nonrandomized study and both groups were compared historically. All 322 patients in group 1 (mean age 49 years, range 14 to 86) primarily underwent ureteroscopic stone basket manipulation using the 4-wire Segura* basket. If the calculus could not be removed with the basket and another procedure was necessary, the case was considered a failure. The 161 patients in group 2 (mean age 37 years, range 14 to 74) underwent initially ultrasound ureterolithotripsy for stone fragmentation followed or not by removal of the fragments with the basket. Stone size did not differ significantly between groups 1 (mean 0.9 cm., range 0.6 to 1.7) and 2 (mean 0.8 cm., range 0.7 to 2.0). Ureteroscopy was performed in both groups with epidural anesthesia and on an outpatient basis in the majority of cases. RESULTS: The stone-free rate after 1 procedure was 98.1 and 95.6% in group 1 and 2, respectively. For group 2 versus group 1 the operative time was longer (mean 50, range 25 to 90 versus mean 19 minutes, range 11 to 40, respectively, p < 0.001), the complication rate was greater (16.1 versus 4.3%, respectively, p < 0.001) and average hospital stay was longer (2.1 versus 0.15 day, respectively, p < 0.001). CONCLUSIONS: Ureteroscopic stone treatment with basket manipulation under fluoroscopic guidance or ultrasound ureterolithotripsy provided a high stone-free rate. However, stone removal with the basket manipulation technique should be considered the first choice for treatment of small distal ureteral calculi based on the minimal morbidity, and short operative and recovery times.

Tratamento da pielonefrite aguda com a pefloxacina / treatment of the acute pyelonephritis with pefloxacin

De 35 pacientes com pielonefrite aguda, inicialmente triados para participarem do estudo, 28 receberam tratamento com 400 mg de pefloxacina, uma quinolona fluorada, duas vezes ao dia, por um período de 10 dias. Todos os pacientes foram acompanhados, clínica e laboratorialmente, por cerca de 40 dias. O índice de sucesso, ou seja, cura clínica e laboratorial, foi de 96,3 por cento. Três pacientes (10,7 por cento) apresentaram reaçao adversa, caracterizada por intolerância gástrica. Em apenas um paciente foi necessária a suspensao da antibioticoterapia

The importance of the prostate weight in transurethral microwave thermotherapy.

OBJECTIVE: Transurethral resection of the prostate (TURP) is still the gold standard in the treatment of benign prostatic hyperplasia (BPH). Prostate weight could be of importance on the result of transurethral microwave thermotherapy (TUMT). The present study attempted to elucidate this point. MATERIAL AND METHODS: Transurethral microwave thermotherapy (TUMT) was administered to 106 men with BPH. The patients were classified into two groups according to the weight of the prostate. Group 1 comprised 69 patients, aged 52 to 84 years (mean 65 years), whose prostate weighed up to 50 gm. Group 2 comprised 37 men, aged 55 to 87 years (mean 68 years) whose prostate weighed more than 50 gm. Prostate weight was determined by transrectal ultrasound. The protocol included history and physical examination (particularly digital rectal examination), laboratory evaluation (particularly measurement of PSA), transrectal ultrasound and uroflowmetry. The post-void residual urine was measured by urethral catheterization and ultrasound examination. RESULTS: There were 5/106 (4.7%) failure; therefore, a total of 101 patients were followed from 3 to 27 months, mean 7.7 months. Postoperatively, both groups showed improvement of all the parameters analyzed, except PSA (p < 0.01). However, comparison of the two groups for irritative and obstructive symptoms score and uroflow showed no significant difference. The decrease of the post-void residual urine was statistically greater in group 1 (p < 0.01). Group 2 showed a larger reduction in weight in comparison to group 1 (p < 0.01). Complications were observed in 12/101 (11.9%) cases, with no statistical difference between groups. Of a total of 7 patients with ejaculatory disorders, 5 patients with smaller prostate were observed. Recovery was not seen at more than 6 months follow up. CONCLUSION: The results showed no correlation between the prostatic weight and the efficiency of TUMT in the treatment of BPH.

[Treatment of benign prostate hypertrophy using Prostatron: a study of the effects of treatment temperature elevation]. / Traitement de l'hypertrophie bénigne de prostate par Prostatron: étude des effets d'une augmentation de la température de traitement.

Transurethral microwave thermotherapy was administered to 91 consecutive men with moderate to severe benign prostatic hyperplasia. Mean patient age was 68 years, with a range of 55 to 87 years. Treatment was given in one 60-minute session, on an outpatient basis and without anesthesia. Of the 91 original patients 67 (73.6%) were followed from 3 to 18 months, mean 6.1 months. The microwave emission was continuously monitored to permit the control of the urethral temperature level. Patients were prospective and randomly assessed into 2 groups: group 1 (34 patients) who underwent treatment with urethral temperature between 42 and 43 degrees C and group 2 (33 patients) treated with higher temperature ranging between 43.1 and 45 degrees C. There was improvement of the irritative and obstructive symptoms, prostate weight and residual urine, in both groups after treatment (p < 0.001). PSA did not show a statistically significant difference after TUMT in both groups. Uroflow improved in both groups after the treatment; however, only the group treated with higher temperature showed statistically significant difference (p < 0.001). In the lower temperature group there were 2/34 (5.8%) failures; both patients were still obstructed and underwent transurethral resection. A total of 2/33 (6%) failures were observed in the higher temperature group. Patients showed no general conditions which might allow the use of anesthesia. Therefore, they underwent a second postoperative microwave treatment after 2 and 3 months with uneventful clinical recovery at an early follow-up. No systemic complications were encountered. There were minor complications such as epididymitis, urethral bleeding and severe micturition discomfort within the first 30 days postoperative.(ABSTRACT TRUNCATED AT 250 WORDS)

Functional and histologic alterations in growing solitary rat kidney as result of extracorporeal shockwaves.

The long-term effects of extracorporeal shockwave lithotripsy (SWL) on children treated for renal calculi are unclear. To study the effects on the immature animal, we evaluated 31 Wistar white rats that underwent right nephrectomy at 30 days of age. At 40 days of age they were divided into three groups: a control group of 10 rats that received no shockwaves; Group I (9 rats) that received 1000 shockwaves at 16.0 kV, and Group II (12 animals) that received 1000 shock waves at 17.2 kV. Six months later at maturity (7 months and 10 days of age), the following parameters were measured: (1) body and renal weight; (2) blood lithium, sodium, potassium, and creatinine; (3) fractional lithium, sodium, and potassium excretion; and (4) clearances of lithium and creatinine. The kidneys were studied grossly and histologically. We found no significant changes in overall animal and renal growth between the post-SWL and control groups. However, there were significant changes in renal function. The animals in Groups I and II presented significant increases in blood potassium compared with the control group. Furthermore, the 1000 x 17.2 kV group showed permanent histologic renal changes, including red cells in Bowman's capsule and glomerular congestion. The disorders caused by SWL are compatible with hyporeninemic hypoaldosteronism, inappropriately low plasma renin activity, and aldosterone deficiency.(ABSTRACT TRUNCATED AT 250 WORDS)

Ejaculatory dysfunction after transurethral microwave thermotherapy for treatment of benign prostatic hyperplasia.

The possibility of retrograde ejaculation or impotence after transurethral resection of the prostate has led to searches for other treatments for benign hyperplasia (BPH). Transurethral microwave thermotherapy (TUMT) was administered to 100 men with a mean age of 61 years and moderate to severe BPH in one 60-minute outpatient session without anesthesia. A urethral catheter was frequently maintained for 5 to 7 days to avoid urinary complaints. Of the 100 original patients, 79 were followed from 3 to 24 months (mean 7.3 months). The prostate volume, irritative and obstructive symptoms, residual urine volume, and urinary flow improved (P < 0.01). No systemic complications were encountered. There were minor complications such as epididymitis, urethral bleeding, and severe micturition discomfort within the first 30 days postoperatively. A total of 7 ejaculatory disorders occurred among 64 patients (11%), 6 complete absences and 1 retrograde ejaculation without recovery for more than 6 months. As TUMT is a fairly new method, further studies must be done to define its effectiveness and safety.

Effects of extracorporeal shockwave lithotripsy on renal growth and function: an animal model.

The long-term effects of extracorporeal shockwave lithotripsy (SWL) on children are unclear. At 40 days of age, with an average weight of 166 g, 34 Wistar white rats were divided into three groups: 9 rats (control group) received no shockwaves, 10 rats (Group 1) received 1000 shockwaves at 16.0 kV, and 15 animals (Group 2) received 1000 shockwaves at 17.2 kV. Six months later, at maturity, body weight; lithium and creatinine; fractional sodium, potassium, and lithium excretion; and the clearances of lithium and creatinine were measured, and the kidneys were studied grossly and histologically. We found no significant changes in overall animal or renal growth between the post-SWL groups and the control group. However, there were significant changes in renal function, mainly in Group 2; the animals of this group presented a significant increase in blood lithium and potassium, besides a significant decrease in the fractional potassium excretion compared with the control group. Furthermore, the animals in Group 2 showed permanent histologic renal changes, including red cells in Bowman's capsule and glomerular congestion. The disorders caused by SWL are compatible with hyporeninemic hypoaldosteronism, an inappropriate low plasma renin activity and aldosterone deficiency. We conclude that SWL does not affect either overall animal or renal growth but may cause permanent histologic damage and significant changes in renal function.

Is percutaneous monotherapy for staghorn calculus still indicated in the era of extracorporeal shockwave lithotripsy?

Staghorn stones can be treated by percutaneous nephrolithotomy (PCNL) or by extracorporeal shockwave lithotripsy (SWL); however, the combination of the two techniques appears as the most frequent treatment. In a previous study, the investigators noted that staghorn calculi treated with PCNL monotherapy have a good clearance rate. Herein, we have reviewed 102 staghorn stones that underwent PCNL before (1984-1986) (Group 1; n = 51) and after (1987-1990) (Group 2; n = 45) the introduction of SWL. The stone burden has increased in both size and complexity: there were 27 complete staghorn calculi (60%) in Group 2 compared with 19 (37%) in Group 1. Despite the higher number of kidney punctures, blood urea nitrogen and serum creatinine measurements demonstrated improvement of renal function postoperatively. The stone-free rates were 78% and 89% and the retreatment rates 31% and 18% in Groups 1 and 2, respectively. Complications (29% and 38%) were a function of the technical factors that become more apparent in the more difficult cases. Our data support the concept that the surgeon should have no previous intention to use the lithotripter and, therefore, should try to remove the entire stone percutaneously safely and economically.