Polyvinylidene fluoride monofilament sutures: can they be used safely for long-term anastomoses in the thoracic aorta?

Polyvinylidene fluoride (PVDF) represents an attractive alternative to polypropylene as a monofilament vascular suture because of its satisfactory physicochemical properties, it ease of handling, and its good biocompatibility. However, the polymer's ability to remain mechanically and chemically stable when exposed to a mild hydrolytic environment over the long term has yet to be demonstrated. One in vitro study involved the comparison of the long-term relative resistance of PVDF and polypropylene sutures to hydrolysis for a period of 9 years. The PVDF suture showed major molecular rearrangements from the original ratio of three crystalline structures to the single beta crystalline phase. The observation of some surface oxidation and water inhibition did not significantly modify the tensile strength of the PVDF suture, which retained 92.5% of its original value. In contrast, the polypropylene sample did not undergo any recrystallization but was associated with more oxidation byproducts and more water molecules near the surface, which contributed to a 46.6% loss in initial tensile strength. An in vivo study confirmed that PVDF sutures are biocompatible and are able to maintain satisfactory biostability when used to anastomose thoracic aortic allografts for a period of 6 months in the dog. The cellular reaction of fresh allografts as well as the control autografts to PVDF sutures was minimal. In other allografts that had been preserved in a supplemented medium for 1 week prior to implantation, the PVDF sutures healed satisfactorily with the formation of neocollagen and few macrophages surrounding the monofilament. No evidence of instability at the allograft-host artery junction was observed, confirming that the PVDF sutures were able to ensure a secure anastomosis in the thoracic aorta. PVDF sutures have demonstrated superior long-term biostability in vitro and minimal tissue response in vivo. These are two essential requirements when evaluating the use of a suture for vascular surgery in general and thoracic aortic surgery in particular.     

Comparison of evaluation scales and performance tests for measuring the severity of cyclothymic depressions

Usually the severeness of cyclothymical depression is assessed by self-or arbiter's evaluation scales. These assessments are influenced by - mainly verbal - disturbing variables that hitherto may hardly be controlled. Measurements of performance provide less falsified results. However, they are influenced by the premorbid level of general intelligence and by the age of the patient. These disturbing variables, however, can be controlled rather well. Empirical investigations show that the assessment of the severeness of cyclothymical depression measured by performance tests of evaluation scales leads to different results. Nevertheless, both types of tests are valid for measuring depressions. Therefore, both are to be taken into account for assessment of severeness.     

Development of an instrument for clinical evaluation after surgery for neuromuscular scoliosis

Surgical treatment for neuromuscular scoliosis is effective for most patients. Although those afflicted constitute a heterogeneous group, the aim of surgical treatment is approximately the same for all patients: a spine balanced in the coronal and sagittal planes over a level pelvis. Surgery results in a more stable and straighter spine, which should in turn improve performance in different activities. Previous evaluations of surgery for neuromuscular scoliosis reported in the literature have focused primarily on Cobb angles; there are very few studies dealing with the ability to perform various activities. A new tool for evaluation was developed in several steps, starting with a telephone interview with patients who had undergone surgery and a literature search. The evaluation instrument was then developed, followed by a pilot study and validation of new parts of the instrument. The instrument focuses on performance components and on activity performance. Eight items are evaluated before and after surgery. These data are complemented by a questionnaire administered to the patient or relatives at follow-up. The new parts of the instrument were developed specifically for patients with neuromuscular scoliosis, and the data obtained have been shown to have a high correlation with established measures of activities of daily living of daily living). They should therefore provide us with useful information concerning functional gains as a result of surgery as well as the effect of surgery on activity performance.     

Behavior of sutures used in anterior cruciate ligament reconstructive surgery

The presumed stellar characteristics of clinical pathways have grown in unearthly proportions to the extent that our expectations of pathway utilization are unrealistic and unfounded. Therefore, before expectations go unmet and dissatisfaction with clinical pathway outcomes becomes prevalent, we must objectively analyze the clinical pathway phenomenon and understand the origins, elements, and purpose of this clinical improvement technique.     

Anastomosis in digestive surgery: results of single layer sutures with absorbable and non-absorbable material

The authors report the results of a study performed among 280 single layer extramucous interrupted stitches digestive inverting anastomosis, for a total amount of 661 anastomosis made in patients hospitalized for different digestive pathology, from 1975 to 1981. The single layer sutures were performed with absorbable material in 43,35% of cases and with non absorbable in 54,64%. The Authors report the incidence of precocious and retarded complications regarding the type of the some anastomosis and the material used. The Authors conclude, also on the basis of observed cases, that the anastomosis, performed with slowly absorbable materials, afford better results and fewer complications than those performed with non absorbable materials.     

Analytical and clinical evaluation of new diagnostic tests for myocardial damage

We tested the hypothesis that preventing cyclic GMP degradation with zaprinast, (a selective cyclic GMP-phosphodiesterase inhibitor) would produce a blunted reduction in myocardial O2 consumption in renal hypertension (One Kidney-One Clip, 1K1C)-induced cardiac hypertrophy. Four groups of anesthetized open-chest New Zealand white rabbits (n = 26) were utilized. Either vehicle or zaprinast (3 x 10(-3) M) was applied topically to the left ventricular surface of control or 1K1C rabbits. Coronary blood flow (radioactive microspheres) and O2 extraction (microspectrophotometry) were used to determine O2 consumption. Myocardial cyclic GMP levels were determined by radioimmunoassay. The 1K1C rabbits had a greater heart weight-to-body weight ratio (2.94 +/- 0.08 g/kg) than controls (2.58 +/- 0.17). Systolic blood pressure was higher in 1K1C (102 +/- 9 mm Hg) than in controls (86 +/- 3). Zaprinast significantly and similarly increased cyclic GMP in both control (3.90 +/- 0.47 to 4.66 +/- 0.89 pmol/g) subepicardium (EPI) and (5.08 +/- 0.69 to 7.06 +/- 1.36) subendocardium (ENDO) and 1K1C hearts (5.53 +/- 0.61 to 7.48 +/- 1.51 EPI and 6.48 +/- 0.42 to 8.88 +/- 1.08 ENDO). Myocardial O2 consumption (ml O2/min/ 100 g) was significantly lower in controls treated with zaprinast (EPI: 8.8 +/- 0.1; ENDO: 9.5 +/- 1.9) than in controls treated with vehicle (EPI: 13.6 +/- 1.3; ENDO: 16.2 +/- 2.9). This effect was diminished in 1K1C rabbits treated with zaprinast (EPI: 10.3 +/- 2.4; ENDO: 11.2 +/- 2.6) compared with the vehicle-treated 1K1C group (EPI: 13.3 +/- 1.2; ENDO: 14.5 +/- 2.4). There was a similar increase in myocardial cyclic GMP after treatment with zaprinast, but a greater depression of myocardial O2 consumption in control animals than in 1K1C after treatment with zaprinast. This suggested that the reduction in myocardial O2 consumption, related to increases in cyclic GMP caused by cyclic GMP-phosphodiesterase blockade, was less in 1K1C cardiac hypertrophy.     

Variations in role-play tests of heterosocial performance.

Examined the effects of varying the confederates' (Cs') prompt latency on the heterosocial performance of 140 low- and high-frequency male undergraduate daters. Results indicate that (a) variations altered the test's content and absolute difficulty level, (b) the level at which the Cs' prompt latency was standardized affected the role-play's ability to differentiate between criterion groups, and (c) the ability of the test to differentiate between groups varied across Cs, possibly due to differences in attractiveness. (4 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Validity and fairness of physical ability tests for predicting performance in craft jobs.

Problems relating to performance, accidents, and turnover in outdoor telephone craft jobs stimulated 2 experiments aimed at developing and validating a physical test battery. Based on job analysis results, a battery of 9 measures was administered to a sample of 128 Ss (83 males and 45 females) in Exp I. A 2-test battery (dynamic arm strength and reaction time), valid for predicting job task performance and turnover, was selected. Regression equations for males and females were not significantly different. Exp II included a sample of 210 Ss (132 males and 78 females). A 3-test battery consisting of a body density measure, a balance test, and a static strength test was selected based on relationships with training performance. No significant differences were found in the regression equations for males compared to females. The Exp II battery was also significantly related to field performance, training completion, and accidents and was valid for the Exp I criteria. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Current practice in the preoperative evaluation of patients undergoing major vascular surgery: a survey of cardiovascular anesthesiologists

Comparison was made of the masseter muscle reflexes evoked by tapping on osseointegrated single-tooth aluminum oxide implants, and on natural teeth in nine patients. Tapping on eight out of nine patients evoked an inhibitory masseter muscle reflex, whereas tapping on all of the natural teeth evoked an inhibitory reflex. The threshold for this reflex was clearly elevated in implants compared to natural teeth. The pathway for the impulses responsible for this reflex and the clinical implications of the elevated threshold are discussed.     

Assessment of cardiovascular perioperative risk in non-cardiac surgery

Patients with cardiovascular disease undergoing non cardiac surgery are exposed to three cardiac risks: myocardial infarction, heart failure and death. To estimate cardiac risk, clinical predictors of perioperative cardiovascular risk are classified as major, intermediate and minor and non cardiac surgery is stratified in high risk (greater than 5%), intermediate (from 1 to 5%), minor (lower than 1%) procedures. Efficient perioperative assessment of cardiac patients is obtained by teamwork and usually, indications for further cardiac investigations are the same as those in the nonoperative setting. An simplified algorithm, easier to use than original algorithm given in the guidelines of the American college of cardiology and the American heart association, may be helpful for the indication of further investigations. Five questions must be answered before using algorithm: is it an emergency surgical procedure?, was a coronary revascularization required in the past five years? has the patient had a coronary evaluation in the past two years?, are there identified clinical predictors of cardiac risk?, is it major or minor surgery? Three tests evaluate the preoperative cardiac risk: exercise testing, dipyridamole thallium scintigraphy, dobutamine stress echocardiography. Their accuracy is similar, their negative predictive value is high, their positive predictive value is low. These guidelines may be helpful to indicate further cardiac investigations which will have an impact on patient's treatment, monitoring during or after surgery and outcome.     

A model for the design and evaluation of algorithms for closed-loop cardiovascular therapy

Developing a clinically useful closed-loop drug delivery system can be extremely time consuming and costly. One approach to reducing the time and cost associated with developing closed-loop systems is to reduce the number of animal experiments and perform an extensive set of simulation studies. Through simulations, a closed-loop controller's performance can be evaluated over a complete spectrum of the patient population, including boundary conditions. Simulation studies are repeatable, offering significant advantages in comparing modifications in control algorithms. Finally, simulation studies can be performed in a fraction of the time required for animal studies, at a fraction of the cost. We have developed a simulator, that included a nonlinear pulsatile-flow cardiovascular model, a physiological regulatory mechanism, and the pharmacology of four frequently titrated cardiovascular drugs. This simulator has already been used in the design and evaluation of two closed-loop algorithms-a self-tuning regulator (STR) and a multiple model adaptive controller (MMAC)-for blood pressure control during and after cardiac surgery.     

Comparative evaluation of serological tests for diagnosis of visceral leishmaniasis

Sensitivity and specificity of the direct agglutination (DAT) and indirect immunofluorescent test (IFT) have been compared with indirect immunoperoxidase assay (IPA) for the serodiagnosis of visceral leishmaniasis. IPA and DAT were found to be more sensitive and specific than IFT. Indirect immunoperoxidase test was found to be better than DAT as preparation of antigen is easy. Less amount of antigen is required, storage of antigen in slide form is more convenient and shelf life is longer. It is easier to read and interpret immunoperoxidase with the help of ordinary light microscope and chances of false positive and false negatives are negligible.     

Ceftizoxime interpretive criteria for in vitro susceptibility tests with Neisseria gonorrhoeae

Ceftizoxime was tested in triplicate against 100 clinical strains of Neisseria gonorrhoeae in accordance with National Committee for Clinical Laboratory Standards guidelines to establish susceptibility testing interpretive criteria. The MICs for 50 and 90% of the strains tested were 0.008 and 0.03 microgram/ml, respectively. These results confirm those of other studies reporting ceftizoxime's excellent activity against gonococci. Because no resistant strains were identified, a breakpoint MIC of < or = 0.5 microgram/ml was selected, with a correlate zone diameter of > or = 32 mm. Ceftizoxime appears to represent an alternative to other beta-lactamase-stable beta-lactams for cost-effective therapy of uncomplicated gonorrhea.     

Statistical applications for in vitro diagnostic tests and other medical device clinical trials

Some statistical methods applied to in vitro diagnostic tests for the three primary indications (screening, diagnosis, and monitoring) are discussed. Various examples with practical statistical applications are presented, including test for k by k ordered categorical matched-pair data for screening of cervical cancer, receiver operating characteristic (ROC) curve for diagnosis or screening, and the Cox time-to-event model to estimate relative risk of first cancer progression by monitoring carcinoembryonic (CEA) levels for stage IV breast cancer patients.     

Validation of cardiovascular fitness field tests in children with mental retardation

The validity of the 600-yard walk/run, the 20-m shuttle run, and a modified 16-m shuttle run was determined to measure aerobic capacity (VO2peak) in children with mild and moderate mental retardation. Practice sessions for all tests were conducted. All field tests were very reliable, and VO2peak was significantly related to them all. A stepwise multiple regression showed that field test performance, body mass index (BMI), and gender, but not age, were also significant predictors of VO2peak. All field tests were valid and reliable indicators of aerobic capacity, suggesting that these tests can be used to predict VO2max in children with mild and moderate mental retardation.     

An in vitro evaluation of distractors used for osteogenesis

OBJECTIVE: The objective of this investigation was to evaluate and compare the mechanical behaviors of distractors used for osteogenesis under various conditions by means of common engineering standards. STUDY DESIGN: Five groups of 5 synthetic mandibles were used in this study (N = 25). The first portion of the investigation compared mandibles without intervention (group A [controls]; n = 5), mandibles that had uniform osteotomies stabilized with an external distractor (group B; n = 5), and mandibles that had simulated sagittal osteotomies rigidly fixated with 3 positional screws (group C; n = 5). The second portion of the investigation compared uniform osteotomies (group B; n = 5) and uniform corticotomies (group D; n = 5) that were stabilized with the same external distractor. The last portion of the investigation compared osteotomies stabilized with an external distractor (group B; n = 5) and osteotomies stabilized with an internal distractor (group E; n = 5). Each construct was subjected to vertical loads on a mechanical testing unit. Common engineering standards, including yield load, yield displacement, maximum load, displacement at maximum load, and stiffness, were measured, recorded, and compared by means of a 1-way analysis of variance and a Scheffé multiple comparison test or independent-samples t test. The means between groups were considered significant for P < .05. A polynomial best-fit curve was calculated for the load/displacement data for each group. RESULTS: During the first portion of the investigation, no significant differences were noted between the control, rigidly fixated sagittal osteotomy, and external distractor with osteotomy groups for displacement at maximum load (P = .19). Significant differences were noted between groups for yield displacement (P = .009), yield load (P < .001), maximum load (P < .001), and stiffness (P < .007). Failures occurred in the control and rigidly fixated groups with fractures of the synthetic mandibles. Failures occurred in the external distractor group with permanent deformation or torsion of the pins. During the second portion of the experiment, no statistically significant differences were noted between the corticotomy and osteotomy groups in stiffness (P = .363), maximum load (P = .207), or yield displacement (P = .940). Statistically significant differences were noted between groups for yield load (P = .036) and displacement at maximum load (P = .010). Failures occurred in both groups with permanent deformation or torsion of the pins. During the last portion of the investigation, statistically significant differences were noted between the external distractor and internal distractor groups in yield load (P < .001), yield displacement (P < .001), maximum load (P = .001), and displacement at maximum load (P = .01); no significant differences were noted in stiffness (P = .71). Failures occurred in the external distractor group with permanent deformation or torsion of the pins. Failures occurred in the internal distractor group with fracture of the model or displacement beyond 30.0 mm. CONCLUSIONS: Different patterns of mechanical behavior were found between the control and rigidly fixated sagittal osteotomy groups and the external distractor group, between the corticotomy and osteotomy groups, and between the internal and external distractor groups.