Electrically stimulated colonic reservoir for total anorectal reconstruction

Total anorectal reconstruction after abdominoperineal excision of the rectum has failed to achieve perfect continence. Electrically stimulated reservoir evacuation in combination with an electrically stimulated gracilis neoanal sphincter might improve results. A J pouch was constructed in an isolated colonic loop of seven dogs. Bipolar square wave pulses were delivered via two intramural stainless steel electrode pairs at 10 Hz. Stimulation parameters were varied to achieve adequate contraction. Serosal strain gauges recorded spontaneous and stimulated pouch motility. Evacuation was quantified by a volume displacement technique and observed fluoroscopically. Recordings were performed for a median of 3 (range 1-11) months. At 10 Hz and 0.5 ms pulse width, stimulation was required for 2 min and at voltages of 15 V (n = 4), 18 V (n = 1) and 20 V (n = 2) to obtain a contraction of amplitude comparable to that of a spontaneous contraction. Suprathreshold stimulation invariably resulted in colonic pouch contraction. The mean(95 per cent confidence interval (c.i.)) stimulus-response latency was 25.5(1.9) s. The mean(95 per cent c.i.) intraluminal pressure generated during stimulation was 114.1(17.0) cmH2O and 64.6(12.0) cmH2O during spontaneous activity (P < 0.001). In conclusion, electrical stimulation via intramural electrodes produced contraction generating sufficient intraluminal pressure to effect evacuation of a canine colonic pouch. This has potential for incorporation with an electrically stimulated neoanal sphincter in total anorectal reconstruction to improve evacuation and continence.     

Mayo Clinic long-term analysis of the functional durability of the AMS 800 artificial urinary sphincter: a review of 323 cases

PURPOSE: We determine the long-term durability of the AMS 800* artificial urinary sphincter in the correction of severe urinary incontinence, and evaluate mechanical versus nonmechanical failure and reoperation rates before (1983 to 1987) and after (1988 to present) the introduction of the narrow backing occlusive cuff design. MATERIALS AND METHODS: From January 1983 to October 1994 more than 400 patients received an AMS 800 artificial urinary sphincter placed by 1 surgeon and 323, mean age 60.4 years, met study requirements for review. Mean followup was 68.8 months (range 18 to 153). Only patients with a minimum of 18 months of followup were included in the study. Of the 313 men and 10 women in the study group sphincters were placed at the urethra in 272 and at the bladder neck in 51. All patients were followed from surgery to the date of sphincter failure. Etiology of the failures was recorded and divided into mechanical versus nonmechanical sphincters placed before and after the introduction of the narrow backing cuff. RESULTS: Overall, 58 of the 139 patients (42%) in the pre-narrow backing cuff group versus 31 of the 184 (17%) in the narrow backing cuff group required a first reoperation. Mechanical failure occurred in 29 cases (21%) with the pre-narrow backing and 14 (7.6%) with the narrow backing cuff. Nonmechanical failure developed in 24 cases (17%) with the pre-narrow backing and 17 (9%) with the narrow backing cuff. Ultimately 437 operations were required in the 323 patients, of whom 234 (72%) required no further surgical intervention at a mean followup of 68.8 months. CONCLUSIONS: Technological advances in the design and construction of the AMS 800 have dramatically decreased the reoperation and failure rates. These advances and improved surgical techniques provide an excellent long-term solution and increased continence in correctly selected patients with urinary incontinence.     

Transurethral balloon dilation of the external urinary sphincter: effectiveness in spinal cord-injured men with detrusor-external urethral sphincter dyssynergia

The authors investigated balloon dilation as a minimally invasive alternative to transurethral external sphincterotomy for the treatment of detrusor-external urethral sphincter dyssynergia (DESD). Seventeen spinal cord-injured men with voiding pressures greater than 60 cm H2O underwent balloon dilation of the external sphincter to 90 F at 4 atm of pressure for 10 minutes. The mean voiding pressures before and 12 months after dilation were 83 cm H2O +/- 35 and 37 cm H2O +/- 15, respectively (P = .008). There was a significant decrease in residual urine volume, from 163 mL +/- 162 to 68 mL +/- 59 (P = .05), whereas bladder capacity remained relatively unchanged at 253 mL +/- 181 and 230 mL +/- 97 (P = .30). Complications included one case of postoperative bleeding necessitating transfusion, two treatment failures, and one bulbous urethral stricture. Fourteen of the 17 patients (82%) now void without the aid of an indwelling catheter or alternative therapy. Balloon dilation has no detrimental effect on erectile function and may improve fertility.     

Partial Fourier reconstruction for three-dimensional gradient echo functional MRI: comparison of phase correction methods

Partial Fourier (PF) methods take advantage of data symmetry to allow for either faster image acquisition or increased image resolution. Faster acquisition and increased spatial resolution are advantageous for fMRI because of increased temporal resolution and/or reduced partial volume effects, respectively. Standard PF methods, which use a phase reference obtained from a low resolution image, are adequate for the reconstruction of time-stationary images acquired using either spin echoes or short TE gradient echoes. In fMRI, however, multiple images are acquired using long TE gradient echoes, which introduces possible phase drifts in the fMRI data and high spatial frequencies in the phase reference. This work investigates several techniques developed to reconstruct fMRI data obtained with PF acquisitions. PF methods that account for both high-frequency spatial variations and time-dependent drifts in the phase reference are discussed and are quantitatively evaluated using receiver operator characteristic curve analysis.     

Vector manometric study of the sphincter of Oddi in the dog: functional and morphological correlation

BACKGROUND: Clinical use of cyclosporine (CsA) is limited by its known nephrotoxicity. Parathyroid hormone (PTH)-related protein (PTHrP) increases after acute renal ischemia and stimulates proliferation of renal cells in culture. Herein, we have examined whether the renal expression of PTHrP and its PTH/PTHrP receptor is affected by chronic CsA nephrotoxicity. METHODS: Rats were randomly assigned to receive daily intramuscular injections of either CsA (25 mg/kg) or the same volume of the vehicle olive oil (control) for 3 weeks. At this time interval, under ether anesthesia, rat blood and kidneys were obtained for analytical determinations, and total RNA isolation or immunohistochemistry, respectively. RESULTS: Serum urea was 11+/-2 and 6+/-1 mmol/L (P < 0.01) in CsA-treated and control rats, respectively. We found that PTH/PTHrP receptor mRNA was unchanged, but PTHrP mRNA, and also transforming growth factor-beta1 mRNA expression as positive control, was about twofold increased in the kidney of CsA-treated rats. This was accompanied by increased PTHrP immunostaining in renal cortical tubules, associated with tubule vacuolation. CONCLUSION: This study demonstrates an up-regulation of PTHrP, associated with chronic CsA-induced nephrotoxicity. Our findings support a role for PTHrP in the CsA-injured kidney.     

Xenon-133 resorption in urinary bladder: functional diagnosis of bladder epithelium

The examination of resorption from the urinary bladder had previously been restricted almost exclusively to animal research, since, as a rule, a separation of the bladder from the urinary tract is required. If this is not done, the resorbed test substance quickly finds its way back into the bladder. More than 95 per cent of the xenon which has been resorbed from the bladder becomes eliminated through the lungs. The detection and measurement of xenon in the exhaled air enables one to conduct, in a relatively simple fashion, urinary bladder resorption research using human subjects. Studies based on 141 patients showed that the xenon exhalation tests currently represent the most sensitive and exact method for detecting and determining the nature of inflammatory diseases of the urinary bladder. With a number of so-called "irritable bladder" cases it became clear that functional disorders of the bladder epithelium could be present without any evidence of associated morphologic changes. With radiogenic treatment of tumors in the lower pelvic region one experiences an increase in bladder resorption with increased exposure to radiation. There exists, as it were, a linear correlation between the radiation dosage and the degree of resorption from the urinary bladder. Three months after terminating radiotherapy one can detect, as a rule, only a negligible increase in resorption. If at this time the rate of xenon resorption still remains clearly high, one must reckon with permanent radiation damage of the bladder, insofar as it proves unsuccessful to eliminate the cause of cystitis.     

Rectosigmoid urinary diversion: the functional significance of creating an intussuscepted colorectal valve

PURPOSE: We assess the functional importance of a colorectal valve in patients with rectal urinary diversion. MATERIALS AND METHODS: A retrospective evaluation of 87 patients with an anal sphincter controlled bladder substitute was performed. Of these patients 42 had colorectal valves and 45 did not. Evaluation included serum chemistry studies and arterial blood samples to study the impact of the colorectal valve on homeostasis. RESULTS: There was a statistically significant difference between the 2 groups in pH, carbon dioxide partial pressure, bicarbonate, base excess and chloride in favor of patients with a colorectal valve. CONCLUSIONS: The difference between the groups was reduction of the surface area available for reabsorption when a valve is constructed. This finding is of particular importance among patients with a long life expectancy. Prophylactic alkalization is necessary in cases without valve reconstruction.     

Intracranial facial nerve neurinoma: surgical strategy of tumor removal and functional reconstruction

The effects of a new forskolin derivative, (13R)-spiroforskolin, on the ventricular cAMP-activated chloride current (I(Cl(cAMP))) and the atrial L-type calcium current (I(Ca,L)) were measured by means of whole-cell recording from isolated guinea-pig cardiac myocytes at 30 degrees C and 20-22 degrees C, respectively. In contrast to forskolin, the derivative contains a tetrahydrofuran rather than a tetrahydropyran moiety. (13R)-spiroforskolin activated I(Cl(CAMP)) in 58% of the ventricular myocytes studied. The concentration required for the half maximal effect (EC50 value) amounted to 9.6x10(-11) M and was lower than the EC50 value for forskolin (2.4x10(-8) M). (13R)-spiroforskolin evoked a smaller maximal I(Cl(cAMP)) amplitude than forskolin. The rundown of the (13R)-spiroforskolin-activated I(Cl(cAMP)) was faster than that of the forskolin-induced current. Neither forskolin nor (13R)-spiroforskolin in maximally effective concentrations increased I(Cl(cAMP)) in cells containing high concentrations of cAMP. Furthermore, as an activator of atrial I(Ca,L) (13R)-spiroforskolin displayed a smaller activation and a lower EC50 value (5.8x10(-10) M) than forskolin (EC50 value: 3.7x10(-7) M). The effect of (13R)-spiroforskolin was observed in only 30% of the atrial cells studied. None of the drugs exerted a stimulatory effect in atrial cells containing a high [cAMP]. The washout of the drug effect was significantly faster in (13R)-spiroforskolin- than in forskolin-treated atrial myocytes. We conclude that (13R)-spiroforskolin as a forskolin derivative displays unique characteristics. It is a more potent but less efficacious activator of cardiac ionic conductances than the parent compound. The results suggest that (13R)-spiroforskolin, like forskolin, most probably exerts its effects via stimulation of the adenylyl cyclase.     

Resting and stimulated states in functional imaging studies: evidence of differences in attentional and intentional set

In a [99mTc]-hexamethylpropyleneamine oxime single photon emission computed tomography study of cerebral blood flow (CBF) in a visual activation paradigm (awake, eyes closed versus eyes open viewing a reversing checkerboard pattern), the authors systematically measured previously observed qualitative alterations in frontal blood flow associated with visual stimulation (experiment 1). They confirmed a trend toward reductions in CBF throughout precentral cortex that approached significance in areas 9 and 46, in conjunction with significant increases in CBF in postcentral cortices, including visual association area PO, and areas 3-1-2, 22, and 23. The authors posited that these changes may be related to differences in attentional and intentional state in the eyes-closed and eyes-open conditions. Such differences should be associated with alterations in motor preparedness, leading to changes in response times and to alterations in thalamocortical gating of somatosensory information, which in turn lead to changes in somatosensory-evoked potential amplitudes. In experiment 2, the authors measured simple motor response times to a 1500-Hz tone stimulus and early components of somatosensory-evoked potentials under the same experimental conditions. In the visual stimulation condition, there was a significant increase in the evoked potential amplitude (t = 2.686, p = 0.021), and a significant decrease in response time (t = -2.464, p = 0.031). These observations provided tentative support for their hypothesis. The authors also demonstrated the major effect of normalization assumptions on regional blood flow measurements.     

Composite resection and reconstruction for oral cavity and oropharynx cancer. A functional approach

Composite resection, the standard surgical approach for treating cancer of the oral cavity and oropharynx, results in considerable functional and cosmetic deformity, whether primary closure or flap reconstruction is employed. To minimize these problems, an alternate surgical approach has been developed. Essentials of the procedure include use of a non-lip-splitting visor flap for exposure and excision of the lesion, reconstruction with a skin or dermis graft formed into a pouch to fill dead space created by resection, and routine use of intermaxillary fixation for immobilization of the reconstructed area. In 16 patients undergoing this procedure, the approach had no adverse effect on short-term survival. Complication rate with skin and dermis graft reconstruction was acceptably low. Cosmetic improvement has been gratifying. Skin or dermis graft reconstruction has resulted in very satisfactory functional results in terms of tongue mobility, articulation, mastication, and swallowing.     

Forming independent components via temporal locking of reconstruction architectures: a functional model of the hippocampus

To investigate whether the degree of differentiation in feline mammary carcinoma (FMC) can indicate the post-surgical survival time (PST), tumours were surgically resected from 55 cats and histologically graded according to a method derived from human breast cancer studies. One year after the resection, 26 cats (47.3%) were alive while 29 (52.7%) had died as a consequence of FMC. Formalin-fixed, paraffin wax-embedded sections stained with haematoxylin and eosin were used to classify the FMCs initially, according to the WHO system. Histological grading was then performed on the basis of three main features: degree of tubule formation, nuclear and cellular pleomorphism, and accurate mitotic count obtained from a defined area. Immunohistochemical examination with an anti-actin antibody was used for the accurate detection of "in situ" carcinomas. Age and histological type were not significantly correlated with the PST. Seven tumours (12.7%) were graded as well-differentiated carcinoma (WDC; grade I), 33 (60%) as moderately differentiated carcinoma (MDC; grade II), and 15 (27.3%) as poorly differentiated carcinoma (PDC; grade III). The tumour-related death rates after the first post-surgical year were 0 in cats with WDC, 14 (42.4%) in those with MDC, and 15 (100%) in those with PDC. Six cats with tumours showing extensive myoepithelial differentiation were all alive after 1 post-surgical year. The grading system seemed to have a good predictive value in respect of grades I and III of FMC but not for grade II. Myoepithelial differentiation may be relevant to clinical prognosis in FMC.     

Saccades induced electrically from the dorsomedial frontal cortex: evidence for a head-centered representation

The amplitude and direction of saccadic eye movements evoked electrically from the dorsomedial frontal cortex (DMFC) of monkeys vary with starting eye position. This observation has been used to argue that the DMFC codes saccadic eye movements in head-centered coordinates. Whether the amplitude and direction of the evoked saccades are also affected by changes in head position has never been demonstrated. Such a result would argue against a head-centered representation, and instead would suggest a representation anchored to another body part. Tests were conducted on rhesus monkeys to determine whether changing the position of the head with respect to the trunk or changing the position of the head with respect to the gravitational axis alters saccadic parameters. The amplitude and direction of saccadic eye movements remained invariant to such manipulations. These findings confirm the claim that the DMFC encodes saccadic eye movements in head-centered coordinates.     

Human beta-defensin-1: A urinary peptide present in variant molecular forms and its putative functional implication

Human beta-defensin-1 (hBD-1) was first isolated from blood filtrate by our group. Further studies elucidate the significance of this peptide in the human urogenital tract. The hBD-1 gene is expressed in urogenital epithelial organs such as urinary bladder, ureter, vagina and particularly in distal tubular cells of the kidney. Functional characterization of hBD-1 was carried out with native hBD-1 purified from human body fluids. Several different N-terminally truncated variants derived from the 68-amino acid-containing precursor of hBD-1 occur in blood filtrate and in urine. The generation of these variants can be explained by digestion through a chymotrypsin-like protease. Unlike the alpha-defensins which are structurally related peptide antibiotics, our results indicate that native hBD-1 exhibits minor antimicrobial activity which is not related to the extension of the N-terminus. Only few microorganisms, for example bacilli, are significantly inhibited by hBD-1. Moreover, antibiotic activity is suppressed in solutions containing physiological sodium chloride concentrations. This is in contrast to previous reports assuming a pivotal role of hBD-1 in antimicrobial host defense. In contrast to its weak antimicrobial activity, it is shown that hBD-1 has a strong cytotoxic potential towards mammalian cells like NIH-3T3 fibroblasts. We assume that this property might be important during eradicative processes at epithelia in particular when the synthesis rate of this peptide is upregulated.     

Petrosectomies for invasive tumours: surgery and reconstruction

Tumours involving the temporal bone have historically carried a bad prognosis. The only prospect of cure is radical en bloc resection. Temporal bone resection for malignancies is, however, such a formidable undertaking that many centres label such tumours as unresectable. Additionally, the enormity of the surgical defect poses a major reconstructive challenge. A review of 14 petrosectomies (in 12 males and 2 females) performed for extensively invasive neoplasms in and around the ear is presented. All underwent immediate reconstruction, the majority (12/14) with free tissue transfers. 9 of the 14 patients (64%) are still alive after a mean follow-up of 70 months (range 4-8 years). With the use of free tissue transfers, an aggressive approach with regard to the resection margins can safely be adopted in the full knowledge that the eventual size of the defect need not compromise tumour clearance. Additionally, free flaps provided a reliable dural seal. This approach of radical en bloc resection with free flap reconstruction has decreased the mortality (compared to the literature), while largely reducing the morbidity to that of unavoidable cranial nerve resection.     

Ureterostomy in situ: technique for temporary urinary diversion

Ureterostomy in situ is a simple technique for supravesical urinary diversion. Although it was described a few years ago, it has not gained wide acceptance. From our experience and with slight modifications, we believe there is a place for this procedure as a method of temporary urinary diversion.     

Iterative reconstruction for helical CT: a simulation study

BACKGROUND: The purpose of this study was to evaluate prospectively the efficacy of subtalar distractional realignment arthrodesis in the treatment of calcaneal malunion associated with subtalar arthritis, collapse of height, talonavicular subluxation, malalignment of the heel axis, and widening heel with calcaneofibular abutment. METHODS: Thirty-four patients with severe calcaneal malunion were treated with a lateral approach, lateral decompression, medial subtalar capsulotomy, and distraction and realignment of the subtalar joint with an anteriorly and laterally tapered wedge bone graft. The patients were evaluated with a functional rating scale and radiographs, both before and after surgery. RESULTS: Thirty-two of the 34 patients were evaluated at a mean of 71 months (range, 60-92 months) after the arthrodesis. Solid subtalar fusion was achieved in 31 of the 32 patients. The average gain of subtalar distraction was 12 mm. Neutral or mild valgus alignment was achieved in 26 of the 32 patients. The mean postoperative score (83) showed significant improvement over the mean preoperative score (47). Overall, the functional rating scale revealed excellent or good results in 26 patients and fair results in 6 patients. CONCLUSION: Coupled with wedge bone grafting, the subtalar distractional realignment arthrodesis achieved restoration of hindfoot height and axial alignment with a good union rate and significant improvement in the majority of patients with calcaneal malunion.