Mechanistic Insights into Bioengineered Antibiofilm Enamel Pellicles.

Dental caries remains the most widespread chronic disease worldwide. Basically, caries originates within biofilms accumulated on dental enamel. Despite the nonrenewable nature of the enamel tissue, targeted preventive strategies are still very limited. We previously introduced customized multifunctional proteinaceous pellicles (coatings) for controlling bacterial attachment and subsequent biofilm succession. Stemmed from our whole proteome/peptidome analysis of the in vivo acquired enamel pellicle, we designed these pellicles using hybrid mixtures of the most abundant and complementary-acting antimicrobial and antifouling proteins/peptides for synergetic suppression of early biofilms. In conjugating these domains synthetically, their bioinhibitory efficacy was remarkably boosted. Herein, we sought to explore the key structure-function relationship of these potent de novo hybridized conjugates in comparison with their individual domains, solely or in physical mixtures. Specifically, we interrelated the following facets: physicochemical and 3-dimensional folding characteristics via molecular dynamics simulations, adopted secondary structure by circular dichroism, immobilization capacity on enamel through high-spatial resolution multiphoton microscopy, and biofilm suppression potency. Our data showed consistent associations among the increased preference for protein folding structures, α-helix content, and enamel-immobilization capacity; all were inversely correlated with the attached bioburden. The expressed phenotypes could be explained by the adopted strongly amphipathic helical conformation upon conjugation, mediated by the highly anionic and acidic N-terminal pentapeptide shared region/motif for enhanced immobilization on enamel. In conclusion, conjugating bioactive proteins/peptides is a novel translational approach to engineer robust antibiofilm pellicles for caries prevention. The adopted α-helical conformation is key to enhance the antibiofilm efficacy and immobilization capacity on enamel that are promoted by certain physicochemical properties of the constituent domains. These data are valuable for bioengineering versatile therapeutics to prevent/arrest dental caries, a condition that otherwise requires invasive treatments with substantial health care expenditures.

Laparoscopic-assisted right lobe donor hepatectomy.

The major impediment to a wider application of living donor hepatectomy, particularly of the right lobe, is its associated morbidity. The recent interest in a minimally invasive approach to liver surgery has raised the possibility of applying these techniques to living donor right lobectomy. Herein, we report the first case of a laparoscopic, hand-assisted living donor right hepatic lobectomy. We describe the technical aspects of the procedure, and discuss the rationale for considering this option. We propose that the procedure, as described, did not increase the operative risks of the procedure; instead, it decreased potential morbidity. We caution that this procedure should only be considered for select donors, and that only surgical teams familiar with both living donor hepatectomy and laparoscopic liver surgery should entertain this possibility.

Concentrated autologous plasma protein: a biochemically neutral solder for tissue welding.

BACKGROUND AND OBJECTIVE: Xenographic or allographic serum protein solders used for laser welding may have immunologic and/or pathogenic complications. The objective of these studies was to develop a safe, autologous solder. STUDY DESIGN/MATERIALS AND METHODS: Five methods of preparing concentrated autologous plasma protein solder (CAPPS) were evaluated. Next, the CAPPS was evaluated via (1) thermal denaturation studies using differential scanning calorimetry, (2) tissue welding studies to characterize both acute and healing properties. RESULTS: The optimal concentration method to produce CAPPS rapidly was a dialysis method using chemical (osmotic) forces. The CAPPS showed similar denaturation profiles to serum albumin (SA) solders. Acutely, CAPPS provided comparable breaking strengths to SA solders. At 7 days, there was no significant difference in breaking strength or histology between 50% human SA solder and CAPPS (using a porcine skin model). CONCLUSIONS: These studies demonstrate that the CAPPS system provides acceptable acute and chronic properties for laser welding.

Endometrial evaluation with transvaginal US and hysterosonography in asymptomatic postmenopausal women with breast cancer receiving tamoxifen.

PURPOSE: To determine performance characteristics of transvaginal ultrasonography (US) and hysterosonography for diagnosing endometrial abnormality in asymptomatic postmenopausal women with breast cancer receiving tamoxifen. MATERIALS AND METHODS: The authors prospectively examined 138 women receiving tamoxifen by using transvaginal US, hysterosonography, and office hysteroscopy. The combined hysteroscopic-histopathologic diagnosis was the reference standard. Sensitivity, specificity, positive and negative predictive values, and likelihood ratios of transvaginal US and hysterosonography were calculated. RESULTS: All 138 women underwent transvaginal US; 104, successful hysterosonography; and 117, successful hysteroscopy. Uterine abnormality was present in 47 (40.2%) of 117 women: 45 with polyps and two with submucosal fibroids. Receiver operating characteristic curve analysis revealed 6 mm to be the optimal endometrial thickness cutoff for diagnosing endometrial abnormalities. When a thickness greater than 6 mm or a focal endometrial finding was considered abnormal, transvaginal US had a sensitivity of 85.1% and a specificity of 55.7%. In 92 women who completed transvaginal US, hysterosonography, and hysteroscopy, hysterosonography was more specific (79.2%; P =.008) but not significantly more sensitive (89.7%; P =.508) than transvaginal US. When women with abnormal transvaginal US findings were further examined with hysterosonography, the sequential combination of transvaginal US and hysterosonography was more specific (77.1%) than transvaginal US alone (P <.001), without a significant decrease in sensitivity (78.7%; P =.25). CONCLUSION: In asymptomatic postmenopausal women receiving tamoxifen, 6 mm is the optimal endometrial thickness cutoff for diagnosing endometrial abnormalities with transvaginal US. Further examination with hysterosonography can improve specificity by reducing the high false-positive rate of transvaginal US.

Association of perforation of the appendix with female tubal infertility.

Although perforation of the appendix is considered a risk factor for female tubal infertility, the epidemiologic evidence supporting this relation is inconsistent. Risk factors for tubal infertility were compared for 121 women with documented primary tubal infertility attending in vitro fertilization clinics in Toronto, Canada, from July to December 1998 and 490 controls who were pregnant during the same time period. Self-administered questionnaires and review of medical records were used to assess exposures. The authors found that neither history of acute appendicitis nor perforation of the appendix was a statistically significant risk factor for tubal infertility. The crude odds ratio for perforated appendicitis was 3.4 (95% confidence interval (CI): 0.9, 12.9), and the adjusted odds ratio was 1.4 (95% CI: 0.3, 6.2). In addition to increased age and annual income, cigarette smoking (odds ratio (OR) = 2.0, 95% CI: 1.2, 3.2), history of endometriosis (OR = 6.0, 95% CI: 2.8,12.8), and history of pelvic inflammatory disease (OR = 6.0, 95% CI: 2.8, 12.8) were significantly associated with tubal infertility in multivariate analysis. These data do not provide substantial evidence that perforation of the appendix is an important risk factor for female tubal infertility.

Periurethral autologous fat injection as treatment for female stress urinary incontinence: a randomized double-blind controlled trial.

PURPOSE: We evaluated the effectiveness of periurethral autologous fat injection as treatment for female stress urinary incontinence. MATERIALS AND METHODS: Women with stress incontinence were randomized in a double-blind fashion to receive periurethral injections of autologous fat (treatment group) or saline (placebo group). After injection patients were evaluated monthly for 3 months by a validated standardized incontinence questionnaire, 1-hour pad test and cough test. Patients who remained incontinent were offered repeat injection using the same initial agent to a maximum of 3 injections. Every 3 months after injection patients were assessed by a standardized questionnaire, pad test, cough test and urodynamics. Those who did not qualify for repeat injection at 3 months were then followed 6, 9, 12, 18 and 24 months or until failure. RESULTS: Of the 68 women enrolled 35 received fat and 33 received saline injections. The groups were comparable in terms of baseline parameters. A total of 56 patients completed the study, including 27 in the fat and 29 in the placebo group, for a total of 189 injections (91 fat and 98 saline). At 3 months 6 of 27 (22.2%) and 6 of 29 (20.7%) women were cured or improved in the fat and saline groups, respectively. Complications included cystitis in 9 of 189 injections, urinary retention in 6 in the fat injection group, urge incontinence in 9 of 68 patients and pulmonary fat embolism resulting in death in 1 of 189 procedures. CONCLUSIONS: In this study periurethral fat injection did not appear to be more efficacious than placebo for treating stress incontinence.

Differential scanning calorimetry of albumin solders: interspecies differences and fatty acid binding effects on protein denaturation.

BACKGROUND AND OBJECTIVE: Understanding albumin solder denaturation is important for laser tissue soldering. Human (HSA), bovine (BSA), porcine (PSA), and canine (CSA) albumin both fatty acid containing (FAC) and fatty acid free (FAF) were evaluated by using differential scanning calorimetry (DSC). STUDY DESIGN/MATERIALS AND METHODS: DSC was used to measure difference thermograms to determine the irreversible thermal denaturation profile for 50% albumin solutions. The denaturation transition's onset, end and peak temperatures, and enthalpy were measured. RESULTS: All FAC species, except BSA, exhibited twin peaked endotherms. Single endotherms were observed for all FAF species and BSA-FAC. Onset and end temperatures were significantly [P < 0.001] lower for all FAF species (except BSA's end temperature). There was a 30% decrease in the denaturation enthalpy between FAF and FAC groups. CONCLUSION: FAF albumin solders were found to denature at significantly lower temperatures, while also having a 30% reduction in enthalpy when compared with their FAC counterparts.

Heart booster: a pericardial support device.

BACKGROUND: Congestive heart failure is a pervasive disease afflicting millions of people. For many, their quality of life can be significantly improved by a pericardial device that can enhance cardiac output without the added risk of thromboembolism associated with direct blood contact. METHODS: A cardiac assist device with tubular elements is wrapped around the heart. Fluid is pumped into and out of the wrap causing contraction and dilation of its circumference. This contracting and relaxing action generates cardiac assistance without the need to contact blood. In vitro characterization and in vivo studies in calves were conducted to demonstrate the characteristics of the device. RESULTS: In vitro characterization with the device wrapped around one-half of a ventricle to simulate left ventricular support demonstrated outputs of 6.5 L/min at physiological afterloads. In vivo studies in calves demonstrated both cardiac output and afterload enhancements when the device is activated. CONCLUSIONS: This study provides a first demonstration of a device that provides cardiac support by a contraction and relaxation scheme with the device wrapped around the epicardium of the heart. The main feature of this actuation method is the potential for building a small device for implantation without blood contact.

A new bipolar system for performing operative hysteroscopy in normal saline.

We evaluated the efficacy and safety of the VersaPoint bipolar vaporization system during hysteroscopic treatment of 10 women with symptomatic submucous leiomyomata, endometrial polyps, uterine septa, and synechiae in a prospective, uncontrolled pilot study at two Canadian university-affiliated teaching hospitals. Patients were two women with recurrent pregnancy loss associated with a diagnosis of uterine septa, one with infertility, one with recurrent pregnancy loss and synechiae, and six with menorrhagia associated with either leiomyomata or endometrial polyps. Electrodes were inserted through a 5F operating channel of a 15F cystoscope, and a 17 or 21F hysteroscope. Three electrodes were used: ball, twizzle, and spring. Power settings ranged from 50 W (desiccation mode) to 200 W (vapor cut mode). Normal saline was used as the distention medium in all cases. Either general anesthesia or intravenous sedation with paracervical block was used. There were no major complications such as uterine perforation, excessive bleeding, fluid overload, or thermal injury. The amount of normal saline used varied considerably from 0.5 to 20 L. The maximum amount of saline absorbed was 900 ml in a case involving resection of 4.5- and 2.0-cm leiomyomata that lasted 115 minutes. Mild cramping, vaginal bleeding, and discharge in the first 2 to 3 days were relieved by nonsteroidal antiinflammatory agents. No patients were readmitted up to 6 weeks after the procedure. Preliminary results of this pilot study support the safety of the VersaPoint bipolar vaporization system, although its long-term efficacy remains to be determined. It appears to be well tolerated by some women using conscious sedation and paracervical block. Therefore, it can potentially be used in an office setting as well as in symptomatic patients who are at risk from a general anesthetic. (J Am Assoc Gynecol Laparosc 6(3):331-336, 1999)

Long-term mechanical circulatory support system reliability recommendation: American Society for Artificial Internal Organs and Society of Thoracic Surgeons: long-term mechanical circulatory support system reliability recommendation.

Jointly developed by members of the American Society for Artificial Internal Organs and the Society of Thoracic Surgeons along with staff from the Food and Drug Administration, the National Heart, Lung and Blood Institute and other experts, this recommendation describes the reliability considerations and goals for Investigational Device Exemption and Premarket Approval submissions for long-term, mechanical circulatory support systems. The recommendation includes a definition of system failure, a discussion of an appropriate reliability model, a suggested in vitro reliability test plan, reliability considerations for animal implantation tests, in vitro and animal in vivo performance goals, the qualification of design changes during the Investigational Device Exemption clinical trial, the development of a Failure Modes Effects and Criticality Analysis, and the reliability information for surgeons and patient candidates. The document will be periodically reviewed to assess its timeliness and appropriateness within five years.

Long-term mechanical circulatory support system reliability recommendation: American Society for Artificial Internal Organs and The Society of Thoracic Surgeons: long-term mechanical circulatory support system reliability recommendation.

Jointly developed by members of the American Society for Artificial Internal Organs and the Society of Thoracic Surgeons along with staff from the Food and Drug Administration, the National Heart, Lung and Blood Institute and other experts, this recommendation describes the reliability considerations and goals for Investigational Device Exemption and Premarket Approval submissions for long-term, mechanical circulatory support systems. The recommendation includes a definition of system failure, a discussion of an appropriate reliability model, a suggested in vitro reliability test plan, reliability considerations for animal implantation tests, in vitro and animal in vivo performance goals, the qualification of design changes during the Investigational Device Exemption clinical trial, the development of a Failure Modes Effects and Criticality Analysis, and the reliability information for surgeons and patient candidates. The document will be periodically reviewed to assess its timeliness and appropriateness within five years.

Laparoscopic Two-Team Sling for Stress Urinary Incontinence

The two-team sling procedure is recommended for women with recurrent stress urinary incontinence (SUI), particularly those with low urethral pressures. These procedures have been performed for 20 years using a combined abdominovaginal approach and Marlex mesh. From July 1993 to February 1996, 100 cases of laparoscopic two-team procedures were performed using both extraperitoneal and intraperitoneal approaches. An overall success rate of 95% was achieved with a mean follow-up of 1.5 years (range 6 mo-3 yrs). Complications were small bowel perforation (1%) from the umbilical cannula requiring laparotomy and small bowel resection, inadvertent cystotomy (3%), voiding dysfunction (3%), and mesh erosion (3%). The mean operating time was 70 minutes and average length of hospital stay was 1.5 days. The laparascopic two-team sling is a suitable surgical alternative for women with recurrent SUI.

The cost-effectiveness of laparoscopic versus abdominal Burch procedures in women with urinary stress incontinence.

STUDY OBJECTIVE: To evaluate the cost-effectiveness of laparoscopic versus abdominal Burch procedures in women with urinary stress incontinence (USI). DESIGN: A historical cohort with a minimum follow-up of 1 year. SETTING: Two tertiary, university-affiliated referral centers. PATIENTS: Women with USI who had either a laparoscopic Burch (31 women) or an abdominal Burch procedure (31). They were matched for the type of procedure as well as any concurrent procedures. MEASUREMENTS AND MAIN RESULTS: The primary outcome was cure, defined as the absence of USI subjectively as described by the patient, and objectively as confirmed by urodynamic and stress tests. Cost data were extracted from hospital charts and office records. To calculate costs we assessed professional fees (physicians, nurses, nursing assistants), investigations (laboratory tests, radiology, urodynamics), drugs, capital equipment, disposable equipment, and length of stay. The cure rates were 97% and 90%, respectively. The mean duration of follow-up was 1.2 years (range 1-2.5 yrs) for a laparoscopic Burch and 2.7 years (range 1-9 yrs) for an abdominal Burch. Preliminary results showed a significant difference in cost effectiveness between the procedures. The average cost for a laparoscopic Burch was $2938.35 and for an abdominal Burch $5692.30. The higher costs for abdominal Burch were due to increased hospital stay. The cost-effectiveness ratios (cost/cure) were $3029.23 and $6324.78, respectively. Sensitivity analysis was performed to assess for robustness. CONCLUSIONS: The preliminary results show that a laparoscopic Burch is more cost-effective than the abdominal Burch in treating women with USI.

Temperature-controlled laser photocoagulation of soft tissue: in vivo evaluation using a tissue welding model.

BACKGROUND AND OBJECTIVES: Laser surgical procedures involving photocoagulation of soft tissue have relied on subjective visual endpoints. The thermal damage to the denatured tissue in these procedures is highly dependent on the tissue temperatures achieved during laser irradiation. Therefore, a system capable of real time temperature monitoring and closed loop feedback was used to provide temperature controlled photocoagulation (TCPC). STUDY DESIGN/MATERIALS AND METHODS: The TCPC system consisted of a 1.32 microns Nd:YAG laser, an infrared thermometer, and a microprocessor for data acquisition and feedback control. A porcine skin model was used. Tissue welds were completed to evaluate the photocoagulation effects at different predetermined temperatures. A quantitative measurement of tissue photocoagulation was obtained by tensile strength measurements of the laser repairs. Histology of the irradiated tissue was used to determine the extent of thermal injury associated with different photocoagulation temperatures. RESULTS: The TCPC system was capable of maintaining a relatively constant temperatures (+/- 4 degrees C) during laser irradiation. The tensile strengths of acute repairs increased with temperature over the range studied (65-95 degrees C). Tensile measurements made after several days of healing showed that higher temperature (95 degrees C) welds had lower strengths than repairs completed at lower (65 degrees C or 75 degrees C) temperatures and were significantly lower at 3 days. Acute histology showed that the amount thermal damage was strongly dependent on the tissue temperature and increased both in tissue depth and lateral to the repair with temperature. The histologic results suggest that the increase in the acute repair tensile strength as the weld temperature increased was due to an increase in the depth of tissue photocoagulation. The increase in the lateral tissue injury measured histologically for higher temperature welds likely resulted in the decreased chronic tensile strengths, as a healing response to excessive thermal damage. CONCLUSION: Tissue temperatures can be controlled during laser photocoagulation of skin. The degree of acute and chronic tissue damage is highly dependent on the temperature during welding. By controlling the tissue temperature during laser procedures, the surgical outcome can be more reliably predicted and reproduced, as compared to the conventional open loop methods. In addition, the use of a TCPC system should significantly reduce the learning curve for photothermal surgical procedures.

Laser assisted vascular welding with real time temperature control.

BACKGROUND AND OBJECTIVE: Previous studies in laser assisted vascular welding have been limited by the lack of a reliable end point for tissue fusion. As a means of improving the reproductibility of laser assisted repairs, a system incorporating real time temperature monitoring and closed loop feedback was used. STUDY DESIGN/MATERIALS AND METHODS: The system consisted of a direct view infrared thermometer for monitoring the laser heated spot, a 1.9 microns diode laser, and a microprocessor for data acquisition and feedback control of the laser power to maintain a constant tissue temperature. Rat aortas were welded under constant surface temperature conditions. RESULTS: In vivo temperature stability of +/- 2 degrees C was achieved over a temperature range of 70-90 degrees C pertinent to welding small vessels. When welds were completed using the feedback system to maintain the tissue temperature at 80 degrees C, the acute success rate was 100% and the burst pressure was 290 +/- 70 mmHg. CONCLUSION: These studies demonstrate that the use of real time monitoring and feedback control results in improved consistency for vascular tissue welding.

Absorption characteristics at 1.9 microns: effect on vascular welding.

A 1.9 microns laser was used to investigate the acute weld strengths for anastomoses of rat and rabbit aortas and femoral arteries. The wall thicknesses for these vessels approximately matched the optical absorption depth of 125 microns for 1.9 microns radiation in vascular tissues. A low power (150 mW) 1.9 microns laser was used. Laser power was delivered through silica fiber optics for manual control. The fiber tip was held approximately 1 mm from the target resulting in a laser spot size of 0.7 mm at the tissue. The linear delivery rate was approximately 0.3 mm/sec. Acute burst pressures of the welds showed a linear correlation with the reciprocal of the vessel radius. These results suggest that the product of the weld strength times the optical absorption depth is constant over the range of vessel sizes studied. A weld strength for a weld thickness equal to the optical absorption depth was determined to be 4 x 10(6) dynes/cm2, which is comparable to the strength of sutured anastomoses. These acute studies suggest that a laser wavelength with absorption depth in tissue matched to the vessel wall thickness should yield optimum welds. Therefore, a laser operating near 1.9 microns is suitable for small vessel welding.

Arterial laser welding with a 1.9 micrometer Raman-shifted laser.

A new 1.9 micron Raman-shifted neodymium:yttrium aluminum garnet (Nd:YAG) laser was used for small vessel welding. Bursting pressures and stresses of sutured and laser-welded arteriotomies created in the rat femoral artery and aorta were measured. Sutured arteriotomies had a significantly higher burst stress than laser-welded arteriotomies. Although there were no significant differences in burst stress at the various laser powers tested, an optimal power was identified. The laser was also used to weld transected rat aortas. The average power delivered was 200 mW for 30 seconds per anastomosis. The average time for completing an anastomosis was 6 minutes compared with 18 minutes when sutures were used. In relation to proximal aortic diameter, there was a 7.9% decrease at the anastomosis immediately (n = 4), and a 6.6% and 4.9% increase occurred at 24 hours (n = 4) and 10 weeks (n = 5), respectively. Acute anastomotic compliance, and compliance at 24 hours and 10 weeks were decreased by 47.2%, 39.5%, and 47.8%, respectively, and were similar to sutured anastomoses. Histology showed little thermal denaturation of the aorta within 0.6 mm of the anastomosis, approximately 1 mm of medial cell death, and nearly normal elastic fiber alignment. One focal false aneurysm was noted at 10 weeks. Although the sutured and laser-welded anastomoses share similar compliance changes, the laser-welded anastomoses are more isodiametric. This preliminary experience with the 1.9 micron laser shows the distinct advantages of a handheld fiber, no requirement for cooling irrigation, speed, and no difference in compliance from sutured anastomoses.

A new 1.9-mu wavelength laser for neurosurgery.

The 1.9-mu wavelength component of a 1.9/1.06-mu two-wavelength laser with near-continuous wave properties was tested for its potential use in neurosurgery. The 1.9-mu wavelength has tissue-ablative capabilities, while the 1.06-mu wavelength (Nd:YAG) is suitable for achieving hemostasis. The advantages of the 1.9-mu wavelength over the CO2 laser include its ability to transmit through silica fiberoptic delivery systems and its deeper penetration in water (approximately 100 mu, a depth 10 times greater than for the CO2 laser), which is compatible with irrigation during ablation. To test the effectiveness of the laser, bilateral craniotomies were performed in anesthetized rats immobilized in a stereotactic frame. Under an operating microscope, lesions were made on the cortex by delivering the 1.9-mu laser beam through a 400-mu fiber at an average power of 1 W over a range of fluences. Subjective intraoperative observations were notable for minimal bleeding, absence of charring when the tissue was irrigated with a thin stream of saline, and uniform lesion formation. For comparison, lesions were generated with a commercially available continuous-wave CO2 laser at equivalent power and fluences. Histological specimens were divided into three groups based on the study after laser application: acute (30 minutes), subacute (48 hours), and chronic (14 days). The extent of thermal injury for the 1.9-mu laser in the acute lesions was quantitatively and histologically similar to that generated by the CO2 laser. Regions of injury extended approximately from the apex of the lesion, and crater depths generated by both lasers were similar (250 to 750 mu) in the range of fluences investigated (1.25 to 10 kJ/sq cm). Subacute and chronic histological specimens demonstrated inflammatory and repair responses that correlated with the acute injury regions in both the 1.9-mu and CO2 laser-treated specimens. This study demonstrates a neurosurgical potential for a new two-wavelength laser that ablates tissue effectively with limited thermal injury. The 1.9-mu laser is comparable to the widely used CO2 laser but offers several unique advantages, including the ability for delivery through a fiberoptic system and to irrigate tissue during use.