Computational and Experimental Study of Thermodynamics of the Reaction of Titania and Water at High Temperatures.

Gaseous titanium hydroxide and oxyhydroxide species were studied with quantum chemical methods. The results are used in conjunction with an experimental transpiration study of titanium dioxide (TiO2) in water vapor-containing environments at elevated temperatures to provide a thermodynamic description of the Ti(OH)4(g) and TiO(OH)2(g) species. The geometry and harmonic vibrational frequencies of these species were computed using the coupled-cluster singles and doubles method with a perturbative correction for connected triple substitutions [CCSD(T)]. For the OH bending and rotation, the B3LYP density functional theory was used to compute corrections to the harmonic approximations. These results were combined to determine the enthalpy of formation. Experimentally, the transpiration method was used with water contents from 0 to 76 mol % in oxygen or argon carrier gases for 20-250 h exposure times at 1473-1673 K. Results indicate that oxygen is not a key contributor to volatilization, and the primary reaction for volatilization in this temperature range is TiO2(s) + H2O(g) = TiO(OH)2(g). Data were analyzed with both the second and third law methods using the thermal functions derived from the theoretical calculations. The third law enthalpy of formation at 298.15 K for TiO(OH)2(g) at 298 K was -838.9 ± 6.5 kJ/mol, which compares favorably to the theoretical calculation of -838.7 ± 25 kJ/mol. We recommend the experimentally derived third law enthalpy of formation at 298.15 K for TiO(OH)2, the computed entropy of 320.67 J/mol·K, and the computed heat capacity [149.192 + (-0.02539)T + (8.28697 × 10-6)T2 + (-15614.05)/T + (-5.2182 × 10-11)/T2] J/mol-K, where T is the temperature in K.

Transbronchial needle aspiration in the diagnosis of bronchogenic carcinoma.

Transbronchial needle aspiration (TBNA) was performed as a diagnostic procedure in 91 consecutive patients ultimately proven to have bronchogenic carcinoma. Results of TBNA were compared, in the same patients, to the diagnostic yield of cytologic examination of sputum, endobronchial brushings and washings, and endobronchial/transbronchial biopsy. The diagnostic yield for sputum was 13 percent (10 of 75); brushings, 40 percent (34 of 84); washings, 29 percent (26 of 89); biopsy, 56 percent (42 of 75); and TBNA, 45 percent (41 of 91). Aspirates were positive in 35 percent of patients with adenocarcinoma, 41 percent with squamous cell carcinoma, 52 percent with large cell undifferentiated carcinoma, and 55 percent of patients with small cell carcinoma. Carinal aspirates were positive in 54 percent (6 of 11); paratracheal aspirates, 57 percent (13 of 23); parabronchial aspirates, 39 percent (11 of 28); endobronchial, 78 percent (7 of 9), and peripheral mass or solitary pulmonary nodule, 40 percent (17 of 42). The overall diagnostic yield for brushings, washings, and biopsy was 64 percent. The addition of TBNA increased the yield to 71 percent. Bronchogenic carcinoma was diagnosed solely by TBNA in six patients, all with extrabronchial or extratracheal lesions. We conclude that TBNA increases the diagnostic yield of bronchoscopy, particularly in patients with extratracheal and extrabronchial lesions. An equally important observation is that TBNA fails to contribute significantly to the diagnosis of cancer in patients with lesions readily accessible by conventional bronchoscopic techniques. Exceptions to this observation include occasional patients with necrotic endobronchial tumors, submucosal lesions, and rarely patients with peripheral lung nodules or masses.

A comparison of the cough stress test and single-channel cystometry with multichannel urodynamic evaluation in genuine stress incontinence.

OBJECTIVE: To assess the predictability and accuracy of a simplified approach--the cough stress test and single-channel cystometry--in the diagnosis of genuine stress incontinence (GSI) by comparing these tests to the more complex multichannel cough urethral pressure profile and urethrocystometry. Conversely, we assessed the predictability and accuracy of the multichannel approach--the cough urethral pressure profile and urethrocystometry--in GSI by comparing these tests to the cough stress test and single-channel cystometry. METHODS: Prospectively, 145 women with complaints of urinary incontinence underwent a complete urogynecologic evaluation. All patients underwent single-channel cystometry with cough stress test and multichannel urethrocystometry with cough urethral pressure profiles in the erect position. Genuine stress incontinence was diagnosed if 1) the patient was seen to spurt urine per urethra with cough at full cystometric capacity in the absence of vesical instability as determined by single-channel cystometry, or 2) the cough urethral pressure profile demonstrated pressure equalization in the absence of vesical instability as determined by multichannel urethrocystometry. Statistical values were calculated for both the simplified and the multichannel methods, and measures of validity were compared statistically. RESULTS: For the diagnosis of GSI, the simplified method had a positive predictive rate of 87.2% and a negative predictive rate of 80.6%. The multichannel method had a positive predictive rate of 84.0% and a negative predictive rate of 84.4%. CONCLUSION: For the diagnosis of GSI, the simplified method of the cough stress test and single-channel cystometry is as accurate and predictive as the multichannel method.

Dietary caffeine intake and the risk for detrusor instability: a case-control study.

OBJECTIVE: To determine whether there is an association in women between caffeine intake and risk for detrusor instability. METHODS: Women were included if they had symptoms of urinary incontinence, completed a 48-hour voiding diary detailing fluid and caffeine intake, and had undergone standardized multichannel urodynamics. The study group had 131 women with detrusor instability on provocative cystometry and maximum urethral closure pressure greater than 20 cm of water. The control group had 128 women without detrusor instability on provocative cystometry and maximum urethral closure pressure greater than 20 cm of water. For statistical comparison, women were divided into the following three groups on the basis of caffeine intake: minimal (< 100 mg/day), moderate (100-400 mg/day), and high (> 400 mg/day). RESULTS: The mean caffeine intake of women with detrusor instability (484 +/- 123 mg/day) was significantly higher than that of controls (194 +/- 84 mg/day, P =.002). On univariate analysis, significant risk factors for detrusor instability were age, smoking status, and caffeine intake. On multivariate analysis, the statistically significant association between high caffeine intake and detrusor instability persisted after controlling for age and smoking (odds ratio [OR] 2.4, 95% confidence interval [CI] 1.1, 6.5, P =.018). When women with moderate caffeine intake were compared with those with minimal caffeine intake, the risk for detrusor instability was lower and did not reach significant levels (OR 1.5, 95% CI 0.1, 7.2, P =.093). CONCLUSION: An association between high caffeine intake and detrusor instability was seen in this population. Larger studies are required to determine whether the association is causal.

Double pessary use in grade 4 uterine and vaginal prolapse.

BACKGROUND: Certain situations dictate conservative management of grade 4 uterine or vaginal vault prolapse in women. The reduction of a prolapse may not be possible if the vagina cannot retain a single pessary. We have used double pessaries in the management of this condition. TECHNIQUE: With the patient in the dorsal lithotomy position, either a Donut or Inflatoball (Milex Products Inc., Chicago, IL) pessary is inserted and pushed into the vagina as far as is comfortable. A second pessary, either a flexible Gellhorn or Shaatz (Milex Products Inc.), then is placed caudad to the first. EXPERIENCE: We have used this approach in five women who have been followed for 7-15 months. There have been no erosions or vaginitis and all the women experienced symptomatic relief. CONCLUSION: In women who want or require conservative management of grade 4 prolapse and are unable to retain a single pessary, the placement of two pessaries often will be successful.

Office screening test for intrinsic urethral sphincter deficiency: pediatric Foley catheter test.

OBJECTIVE: To evaluate an office-based test as a screening method for intrinsic sphincter deficiency. METHODS: One hundred seventy-three women with urinary incontinence were evaluated prospectively by complete urodynamic studies. After catheterization, the pediatric Foley catheter test was performed on an empty bladder by withdrawing the inflated bulb of an 8-French Foley catheter through the urethra. The test was considered positive if the inflated catheter bulb could be withdrawn completely through the urethra. Women with grade 3 genital prolapse or higher were excluded. Intrinsic sphincter deficiency was defined as the presence of genuine stress incontinence and low maximum urethral closure pressure (at most 20 cm H(2)O). RESULTS: Seventy-six of 173 women (44%) had positive tests and 97 (56%) had negative tests. Seventy-six percent of those with positive tests were diagnosed with intrinsic sphincter deficiency, compared with 19% in women with negative tests (P <.001). All women with positive tests and negative cotton swab tests had intrinsic sphincter deficiency. The sensitivity, specificity, and positive and negative predictive values for diagnosing intrinsic sphincter deficiency were 76, 81, 76, and 81%, respectively. CONCLUSION: A positive pediatric Foley catheter test in the absence of urethral mobility strongly suggests intrinsic sphincter deficiency. The pediatric Foley catheter test may be useful in screening for intrinsic sphincter deficiency.

The effect of posterior wall support defects on urodynamic indices in stress urinary incontinence.

OBJECTIVE: To determine if posterior vaginal wall defects affect urodynamic indices and mask stress urinary incontinence. METHODS: Ninety women with grade 0, 1, 2, or 3 posterior wall defects were evaluated prospectively by complete urodynamics to assess their urinary complaints. None had severe anterior or apical support defects. Urethral pressure profilometry and cough stress test were performed with the posterior wall in the unretracted position and then with the posterior wall retracted using a split speculum. Analysis of covariance was used to compare adjusted mean differences in maximum urethral closure pressure, functional urethral length, and units of leakage volume during the cough stress test in the unretracted and retracted positions among the posterior wall grade groups. RESULTS: In women with grade 3 posterior wall defects, there were significant changes from the unretracted to the retracted position in maximum urethral closure pressure of -7.0 cm H20, (99% confidence interval [CI] -12.4, -1.6), functional urethral length of -0.3 cm (99% CI -0.5, -0.1), and leak volume units of +0.7 (99% CI 0.4, 1.0) during the cough stress test. There were four women with grade 3 posterior wall defects who demonstrated potential stress incontinence when their posterior wall was retracted. CONCLUSION: A grade 3 posterior wall defect may artificially raise maximum urethral closure pressure, increase functional urethral length, and mask urinary stress incontinence during a cough stress test. Women with grade 3 posterior wall defects should be tested with the posterior wall retracted during urodynamic evaluation.

Pelvic anatomy for obstetrics and gynecology residents: an experimental study using clay models.

OBJECTIVE: To determine whether clay modeling with lecture is more effective than lecture alone in teaching female pelvic anatomy. METHODS: A pretest preceded a lecture on female pelvic anatomy in the following five groups of obstetrics and gynecology residents: postgraduate year 1 (PGY-1) residents at Women and Infants Hospital of Rhode Island (RI), PGY-1 residents at University of Connecticut (CT), and PGY-2, -3, and -4 residents at RI. The study group (PGY-1 RI) also participated in a clay modeling session. Both groups of PGY-1 residents were tested immediately (posttest 1) and then 8 weeks later (posttest 2). The PGY-2, -3, and -4 residents had only posttest 2. Data were analyzed with parametric, nonparametric, and repeated measures analyses. RESULTS: There was no significant difference between the mean pretest scores of the five groups. The study group showed significant improvement in mean scores at posttest 1 (29.7 +/- 0.9, P <.001) and at posttest 2 (24.1 +/- 4.6, P =.03) compared with the mean pretest score (17.4 +/- 3.7). The CT residents demonstrated significant improvement in mean scores at posttest 1 (25.2 +/- 4.4, P =.02) but not at posttest 2 (19 +/- 3.7, P =.2) compared with their mean pretest score (15.2 +/- 2.9). There was no significant improvement in the mean scores at posttest 2 for PGY-2, -3, and -4 resident groups compared with their pretest scores. CONCLUSION: Clay modeling with lecture was more effective than lecture alone for teaching pelvic anatomy.

Arachnoiditis presenting as a cervical cord neoplasm: two case reports.

Neurological evaluation supplemented by myelography has been highly successful in diagnosing spinal cord tumors. Our experience shows that a widening of the cord on myelography is not always diagnostic of spinal cord tumors. Two patients who presented clinically with evidence of spinal cord tumor and had a widening of the cord on myelography were found to have severe cervical arachnoiditis without any evidence of intrinsic cord abnormality. Hence, cervical arachnoiditis should be considered in the differential diagnosis of spinal cord tumor on myelography.

Surgical management of the frontal sinus.

The management of frontal sinus injury from trauma or operation has been controversial. Case reports and extensive literature review emphasize the importance of careful treatment of the frontal sinus whenever it is violated. The principles of management are reviewed.

The sensitivity of auditory brainstem response testing for the diagnosis of acoustic neuromas.

OBJECTIVES: To determine the sensitivity of auditory brainstem response (ABR) testing for detecting acoustic neuromas and to determine whether the test is less sensitive for detecting small tumors. DESIGN: Retrospective review of the medical charts of 58 patients with acoustic neuroma who had all of the data necessary for inclusion in the study. SETTING: University-affiliated referral practice of one neurotologist. PATIENTS: Patients with acoustic neuromas who had both ABR tracings and magnetic resonance imaging films available for review. MAIN OUTCOME MEASURES: Positive ABR and negative ABR results correlated with tumor size. RESULTS: Tumor size ranged from 0.4 to 7 cm. The overall sensitivity of ABR in diagnosing acoustic neuromas was 90%. However, ABR was progressively less sensitive with decreasing tumor size. Only 7 (58%) of the 12 tumors 1 cm or smaller were detected by ABR. CONCLUSION: Auditory brainstem response testing cannot be relied on for detection of small acoustic neuromas and should not be used as a criterion to determine whether magnetic resonance imaging should be performed when an acoustic neuroma is suspected clinically.

Giant cholesterol cysts of the petrous apex.

The giant cholesterol cyst is a clinical entity distinct from cholesterol granulomas and other destructive lesions of the petrous bone. Preoperative assessment by computed tomographic scan and magnetic resonance imaging is extremely helpful. Attempts at total resection of the lesion are not necessary. Adequate surgical drainage may be established through the mastoid or middle fossa.

Development and utilization of paperless medical records: a unique approach.

The purpose of this article is to describe the development and utilization of a unique paperless medical record system in a large multispeciality group practice setting. The Scott and White integrated health care delivery system provides care over a 34-county area in Central Texas. Since 1988, clinicians at Scott and White have developed a text-based, content-searchable electronic medical record system known as EMRx. This system provides a single clinical data repository that allows patient care activities and aggregate data analyses to occur by using the same set of data on a daily basis. Use of this approach has led to the aggregation of over 9.8 million clinical documents since 1994. Over 1,845 health care providers used the system during May 2000 for direct patient care; 866,114 patient records have been accessed since January 1, 1999 to answer questions related to patient care, quality assurance, outcomes research, and accreditation.

Complications of lumbar spinal fusion with transpedicular instrumentation.

Transpedicular screw fixation systems are coming into wide use as an adjunct to lumbar spinal fusion procedures. This 5-year series included 486 patients who underwent 533 variable screw placement procedures for discal, degenerative, and spondylolytic problems. The wound infection rate was 2.6%: 0.6% deep, 0.9% graft, and 1.1% superficial. The neural injury rate was 1.1% overall: 0.6% related to posterior lumbar interbody fusion and 0.6% related to instrumentation. Technical problems per procedure included 8.1% difficult screw placement, 5.6% nut loosening, and 4.3% screw breakage (1.1% per screw placed). Device modifications have reduced the incidence of screw breakage and nut loosening. No device-related neural injuries occurred in the last 333 procedures. With experience, the device can be applied safely without significantly increasing the risk of neural injury or morbidity.

Rapid bioanalytical determination of dextromethorphan in canine plasma by dilute-and-shoot preparation combined with one minute per sample LC-MS/MS analysis to optimize formulations for drug delivery.

The determination of dextromethorphan in canine plasma is used to demonstrate the high throughput bioanalytical approach of automated dilute-and-shoot (DAS) sample preparation followed by a 1 min isocratic liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis. Dilute-and-shoot preparation is commonly used for the determination of drugs in several biological matrices such as urine and saliva, but is not typically used with plasma samples because the amount of protein present in plasma can lead to a variety of problems including column failure. As a result, plasma sample preparation usually removes protein by precipitation, extraction or filtration; however, the dilute-and-shoot approach solubilizes proteins throughout the chromatographic portion of the assay. The attributes of this approach are compared with a previously validated liquid/liquid extraction procedure for determination of dextromethorphan in plasma. Accuracy and precision of both methods are similar. The lower limit of quantitation (LLOQ) of the dilute-and-shoot approach is much higher at 2 ng/ml versus 5 pg/ml with the liquid/liquid extraction; however, the sample throughput of the preparation portion of the dilute-and-shoot approach is more than 50-fold greater. The ruggedness of the dilute-and-shoot method was thoroughly investigated because of the problems traditionally associated with the direct injection of diluted plasma onto an LC-MS/MS instrument. With the optimal conditions, greater than 1,000 injections of diluted plasma have been successfully performed on a single column in less than 19 h making this technique an excellent approach for the rapid preparation and high throughput of plasma samples containing drug levels in the ng/ml range or higher. Application of this methodology to measure the levels of dextromethorphan in canine plasma to evaluate drug delivery from various formulations is also presented.

Total temporal bone resection for squamous cell carcinoma.

Because of unsatisfactory results in treatment of malignant conditions of the temporal bone, a technique for total en bloc resection of the temporal bone and carotid artery was reported by Graham et al. in 1984. The procedure involves resection of the internal carotid artery, cranial nerves VI through XII, and structures adjacent to the temporal bone. Experience with two additional cases led to numerous modifications in the recommended procedure, as reported by Sataloff and Myers. Additional clinical experience with this technique and its complications has resulted in further modification. Additional pitfalls and specific changes in technique from previous reports are discussed in detail, including a new procedure to assure the adequacy of contralateral venous outflow.

Undermatching: a reappraisal of performance on concurrent variable-interval schedules of reinforcement.

The extant data for pigeons' performance on concurrent variable-interval schedules were examined in detail. Least-squares lines relating relative pecks and time to the corresponding relative reinforcements were obtained for four studies. The between-study group slopes for time and pecks and five of seven within-study group slopes from individual studies were less than 1.00. This suggested the generality that pigeons respond less to the richer reinforcement schedule than predicted by matching. For pecks, a nonparametric test for distribution of points also supported this concept of undermatching (to the richer reinforcement schedule). In addition, using mean squared error as the criterion, a cubic curve fit the peck proportion data better than any line or other polynomial. This indicates that the relation between peck and reinforcement proportions may be nonlinear.

Effects of reinforcer duration on responding in two-link chained interval schedules.

Each of five pigeons was exposed to two or more durations of access to mixed grains on two-link, chained, interval schedules in which both links were identical fixed-interval or variable-interval schedules. Response rates were an increasing function of reinforcer duration for both initial and terminal links. For both types of interval schedules, initial-link response rates were more sensitive to reinforcer duration than were terminal-link response rates. The present results, together with prior ones, suggest that chaining and choice procedures are each sufficient for demonstrating substantial sensitivity of responding to changes in reinforcer duration.

Acute urinary retention and the incarcerated, retroverted, gravid uterus. A case report.

A case of urinary retention was associated with an incarcerated, retroverted, gravid uterus. In a literature review of the English language we encountered 26 similar cases. Although no series of cases has allowed evaluation of a specific protocol for evaluation and management or analysis of outcomes, a review of the literature does outline certain diagnostic tests and treatment modalities that may be useful when one is faced with this uncommon condition.

Patient satisfaction with laparoscopic Burch retropubic urethropexy.

OBJECTIVE: To assess six-month and three- to four-year patient-oriented outcomes after laparoscopic Burch retropubic urethropexy. STUDY DESIGN: Twenty-two women with urodynamically proven genuine stress incontinence with urethral hypermobility underwent laparoscopic Burch retropubic urethropexy. Preoperatively, all 22 women completed a questionnaire concerning their incontinence. Postoperative measures of symptoms of incontinence, impact of incontinence on daily activities and patient satisfaction were assessed at six months and three to four years postoperatively. In those women who were followed, the questionnaire data at the three-time points (preoperative, six months and three to four years) were compared. RESULTS: Thirteen women (59%) completed postoperative questionnaires at six months and three to four years. When compared to preoperative data, there was a significant improvement in symptoms of stress incontinence at six months (P = .0005) and at three to four years (P = .002). There was also a significant reduction in limitations on daily activities at six months (P = .0005) and at three to four years (P = .0005) as compared to preoperative data. Twelve of the 13 women considered their surgery successful at six months and at three to four years. CONCLUSION: After laparoscopic Burch retropubic urethropexy, there was a significant improvement in patient-oriented outcomes, including complaints of incontinence and functional status.