Skin flap closure by dermal laser soldering: a wound healing model for sutureless hypospadias repair

OBJECTIVES: Laser tissue soldering (LTS) with the diode laser and human albumin-hyaluronate-indocyanine green solder is a safe and effective method of providing an immediate leak-free closure during hypospadias repair. In this report, we compare the physiology, histology, and immunohistochemistry of wound healing following LTS and suturing in a rat skin flap model. METHODS: A 4 x 5-cm skin flap was raised and bisected (4 cm) on the dorsum of 48 Sprague-Dawley rats. The central wound was either closed from a dermal approach by suturing or LTS or left open, and studied at 0, 3, 5, 7, 10, 14, and 21 days postoperatively. An intraoperative comparison was made between suturing and LTS with respect to operative time. Postoperatively, flaps were excised for tensiometric analysis, and sections were stained with hematoxylin-eosin to define wound architecture. Resting skin temperature, laser exposed temperature without solder, and maximum temperature with solder (one drop) were measured at the level of the deep dermis, superficial striated muscle layer, and within the solder. Mean peak temperatures were recorded during a 1-minute laser activation time. RESULTS: Mean continuous suturing time (4.9 +/- 1.1 minutes) was significantly (P < 0.001) faster than either LTS (7.7 +/- 0.77 minutes) or discontinuous suturing (8.2 +/- 0.62 minutes). Two seromas (sutured) and two instances of partial wound dehiscence (1 sutured, 1 LTS) were noted. Tensile strength was increased significantly (P < 0.001) for up to 5 days in the LTS group, but was equal to suturing at 7 and 10 days. Immediate tensile strength after LTS was equivalent to a 7-day healed wound. At 14 days, wounds initially left open and those closed by LTS were stronger than sutured wounds (P < 0.05). There was no evidence of thermal injury or foreign body reaction in the LTS group. Solder was incorporated within the dermis in all wounds at 21 days. Laser activation of solder resulted in significant increases in temperature at all three tissue levels: 65.0 +/- 5.2 and 69.9 +/- 6.8 degrees C in the deep and superficial skin (no significant difference between the two), and 101 +/- 15.6 degrees C within the solder (P < 0.001 versus superficial and deep skin). CONCLUSIONS: Our results indicate that sutureless dermal LTS of skin flaps provides increased tensile strength for up to 7 days, with relatively greater tensile strength provided within the first 3 days. Our laser technique does not appear to alter the normal wound healing process. Rather, solder-tissue interaction initially, and extracellular matrix infiltration of solder later, provide the basis for improved wound strength. For hypospadias repair using skin flaps, these wound attributes may permit sutureless surgery.     

The effect of pulpal fluid flow on tensile bond strength of a glass-ionomer cement: an in vivo and in vitro comparison

Previous studies of the bonding capabilities of glass-ionomer cements have concentrated on the use of in vitro testing conditions. Since early moisture contamination appears to have adverse effects on the physical properties of glass-ionomer cements, and with the probability of pulpally derived dentinal fluid being present under in vivo conditions, the objective of this study was to compare in vivo tensile bond strength with in vitro tensile bond strength of a glass-ionomer cement to dentin utilizing the same teeth under similar test conditions. A glass-ionomer lining cement was placed on freshly exposed labial dentin of the maxillary incisor on 10 Rhesus monkeys. Immediately following placement, an orthodontic button was placed over the cement and left undisturbed for 1 hour. The teeth were then extracted and stored in 100% relative humidity for 23 hours. An Instron testing machine was used to register in kilograms the force required to cause tensile bond failure of the cement. Identical methodology was then used on the same teeth for in vitro testing. The concluding results indicate that a statistically significant difference (P < or = 0.05) exists between in vivo and in vitro tensile bond strengths of the glass-ionomer lining cement and that the bond failure was cohesive in character for all cases both in vivo and in vitro. These findings suggest that clinically, tensile bond strengths of glass-ionomer cements to cut dentin can be expected to be weaker in vital teeth than in devital teeth.     

Metalloproteinase inhibitors and wound healing: a novel enhancer of wound strength

BACKGROUND: Wound strength is a balance between collagen synthesis and degradation. The role of collagen breakdown in wound healing is still not well understood. We investigated the role of collagenases (metalloproteinases [MMPs]) in wound healing in using GM6001, a novel inhibitor of MMPs. METHODS: We used the dorsal skin incision model with implantation of polyvinyl alcohol sponges. Twenty male Sprague-Dawley rats were randomly assigned to receive either GM6001 (10 mg/kg body weight) or 2 mL saline subcutaneously. Ten days after operation the animals were killed and fresh wound breaking strength, scar and sponge hydroxyproline content, and collagen type I gene expression in sponges were assayed. In addition, the inflammatory response and the wound fluid cytokine (tumor necrosis factor-alpha [TNF-alpha] and transforming growth factor-beta 1 [TGF-beta 1]) profile were studied. RESULTS: GM6001 significantly increased wound strength (422 +/- 59 vs 302 +/- 33 g, P < .05), whereas scar collagen content did not differ. In the sponge granulomas the inflammatory infiltrate, the collagen content, and the collagen type I gene expression were all significantly decreased by GM6001. CONCLUSIONS: Inhibition of MMP activity during acute wound healing enhances wound strength even though new collagen synthesis and the inflammatory response are significantly decreased. This could be achieved by decreasing collagen turnover or increasing collagen maturation and crosslinking, or both.     

Wound healing of scleral self-sealing incision: a comparison of ultrasound biomicroscopy and histology findings

PURPOSE: The goal of this study was to compare the morphologic findings of wound healing in scleral self-sealing incisions using ultrasound biomicroscopy and histology. METHODS: Using a slit-knife, we made a scleral self-sealing incision in the rabbit eye. At various time points postoperatively, ultrasound biomicroscopy was performed to evaluate wound healing; the eyes then were enucleated and studied histologically. We also performed ultrasound biomicroscopy at various time points postoperatively in patients who received a scleral self-sealing incision during cataract surgery. RESULTS: In rabbit eyes, on days 1 and 2 postoperatively, we detected the scleral wound; thereafter, detection became increasingly difficult. On day 7 postoperatively, the wound was undetectable. By light-microscopic observation, the scleral wound was open at 1 day postoperatively. On day 2 postoperatively, fibrovascular tissue barely extended into the wound; on day 5 postoperatively, connective tissue extended through the full thickness of the wound. On day 7 postoperatively, the connective tissue became dense and aligned with the lamella. In human eyes, using ultrasound biomicroscopy, the scleral incision was detectable until 5 days postoperatively, but undetectable at 7 days postoperatively. CONCLUSIONS: Ultrasound biomicroscopy demonstrates the stages of wound healing of scleral self-sealing incisions. We believe that careful observation is necessary for approximately 7 days following self-sealing incision cataract surgery.     

The shoelace technique for wound closure in open fractures: report of early experience

A simple, reliable method of wound closure in open fractures is presented which has been used in this department. The necessity for split-skin grafting or flap cover, with the associated morbidity and cost implications, has been avoided by using this method. It has not been associated with any major complications in the patients studied, but it should be recognized that this method is not universally suitable in the treatment of all open injuries. We recommend this method as a simple way of achieving soft tissue cover in open injuries which are thoroughly debrided and cleaned, and in which there is no evidence of raised intracompartmental pressure.     

Our experience with the use of a Bulgarian cyanoacrylate tissue adhesive in obstetrical and gynecologic surgical practice

The effect of somatostatin was tested on gastrin release induced by electrical vagal stimulation in anaesthetized cats. The antral release of gastrin was determined in the gastric venous outflow by simultaneous recording of gastrin concentration and blood flow. Repeated vagal stimulation at the same frequency and duration caused release of similar amounts of gastrin within the same cat. Infusion of somatostatin, at a rate of 0.5 microng/kg/min, reduced the vagally induced gastrin release to about 40%. Similarly, basal gastrin output was depressed to about 40% of the control values.     

Risk, motives, and styles of utilization review: a cross-condition comparison

In the United States various forms of managed care have been introduced to control the use of expensive medical services. One of the most prominent involves utilization review of hospital admissions. While reviewing the appropriateness of inpatient treatment is appealing in principle, its application is made difficult by clinical uncertainty. Managed care plans develop and implement review criteria often without the guidance of clear clinical norms of treatment. Under these conditions, we suggest that utilization review organizations (UROs) can be expected to develop "styles" of review that respond to clinical uncertainty, influenced by their experience, professional orientation, and financial incentives. Two review styles are explored in this paper: standardization, where the URO reduces the variance in clinical practices by eliminating those practices that deviate from professional norms and stringency, whereby the URO shifts the distribution of clinical practice as it tries to change the professional norms of practice. Data from a 1992-1993 national survey of utilization review organizations are used to test whether UROs have review styles that systematically respond to organizational attributes, economic pressures, and clinical uncertainty associated with three medical conditions: cardiac catheterization, low back pain, and adolescent depression. UROs were found to adopt more stringent review strategies for conditions with weaker norms of appropriate treatment. Financial incentives and organizational experience are positively related to greater stringency. Standardization responds to professional orientation and organizational experience. Variation in the review styles of UROs has implications for the resulting distribution of clinical practices as well as the equity of access to medical care.     

The tensile strength of 339 aluminum reinforced with kaowool fibers: A comparison of T5 and T6 heat treatments

This study compares the effects of T5 and T6 heat treatment on the tensile strengths of both KAOWOOL fiber reinforced and unreinforced 339 aluminum. The 339 Al-T6 is stronger than 339 Al-T5 (as expected), but for a KAOWOOL/339 Al composite, the T5 condition is substantially stronger than the T6. The controlling parameter is the strength of the aluminum dendrites, which in turn is proportional to the concentration of magnesium retained in the dendrites. In the T5 condition, more than half of the magnesium is in the form of large intermetallics in both the unreinforced alloy and the KAOWOOL/339 Al composite. During a T6 heat treatment, magnesium in the intermetallics is redissolved. In the unreinforced T6 alloy, this additional magnesium is retained in and strengthens the dendrites. But in the T6 composite, the magnesium segregates extensively to the KAOWOOL/aluminum interfaces depleting and softening the dendrites. This factor alone is sufficient to account for the low strength of the T6 composites. The tensile strengths of both the T5 and T6 composites correspond to the calculated values for a perfectly bonded system.     

Galactans and cellulose in flax fibres: putative contributions to the tensile strength

The proton spin-spin relaxation time, T2, measured from solid-state NMR, indicates a greater rigidity for cellulose than for the adhesive matrix between the microfibrils of flax ultimate fibres. Cytochemical and biochemical analyses allow the identification of: (1) EDTA-soluble RG I-polymers in the primary walls and cell junctions of fibres; (2) long 1 --> 4-beta-D-galactan chains between primary and secondary wall layers; and (3) arabinogalactan-proteins throughout the secondary walls. These polymers in the adhesive matrix between microfibrils and/or cellulose layers ensure that cracks propagate along the matrix rather than across the fibres and play an important role in allowing flax fibres to approach the tensile strength of advanced synthetic fibres like carbon and Kevlar.     

The role of mast cell-derived histamine in the closure of an in vitro wound

We have previously reported that mast cells (MC) stimulate 3T3 fibroblast migration and proliferation into an in vitro model of wound obtained by producing in a confluent 3T3 monolayer, a midline cut and by scraping the cells from half of the monolayer. The purpose of the present study was to determine the contribution of mast cell-derived histamine to this MC increasing effect. Histamine levels in supernatants of MC/ 3T3 cultures unactivated or activated with either compound 48/80 or anti-IgE antibodies (10 min) did not correlate to the degree of fibroblast migration and proliferation into the wound space (42 h). Various concentrations of histamine were added to 3T3 fibroblast monolayers in the absence of cocultured MC, and fibroblasts beyond the wound line were counted (42 h). Addition of 100 ng/ml histamine had the highest stimulating effect on fibroblast numbers. This effect was abrogated by the addition of cimetidine (an H-2 antagonist). Addition of cimetidine to unactivated MC/ 3T3 cultures did not affect the increasing activity of MC presence on the wounded monolayer, although it diminished the enhancing effect obtained after MC activation with compound 48/80. These results indicate that histamine is partially responsible for the mast cell enhancing effect on fibroblast migration and proliferation in an in vitro model of wound.     

Validation and utility of a strength test for selecting steelworkers.

168 men and 81 women (mostly steelworkers in the 1st 6 mo of employment) performed a series of work sample (WS) and abstract physical tasks. A measure of static strength, the arm dynamometer, was found to have especially strong correlations with WS performance. Multiple regression analyses revealed no advantage in using more than the arm dynamometer for selection, and bias analyses showed that the measure would have at most a slight adverse impact on males. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The tampon test for trichomoniasis: a comparison between conventional methods and a polymerase chain reaction for Trichomonas vaginalis in women

Vertebral artery tortuosity causing neural foraminal widening is a well described abnormality that should not be confused with other causes of neural foraminal enlargement, particularly on conventional roentgenograms. We, hereby, describe CT features of another cervical osseous change due to the vertebral artery tortuosity, the so called "tubular shaped vertebral artery canal", which is embedded in the vertebral body instead of causing neural foramen enlargement. Catheter and MR angiographic studies have also been performed to confirm the vertebral artery tortuosity causing the osseous changes.     

The influences of impurity content,tensile strength,and grain size on in-service temper embrittlement of CrMoV steels

The influences of impurity levels, grain size, and tensile strength on in-service temper embrittlement of CrMoV steels have been investigated. The samples for this study were taken from several steam turbine CrMoV rotors which had operated for 15 to 26 years. The effects of grain size and tensile strength on embrittlement susceptibility were separated by evaluating the embrittlement behavior of two rotor forgings, which were made from the same ingot, after giving an extended step-cooling treatment. The results reveal that among the residual elements in the steels, only P produces a significant embrittlement. The variation of P and tensile strength of the steels in the ranges investigated has no effect on in-service temper embrittlement susceptibility, as measured by the shift in fracture appearance transition temperature (FATT). However, the prior austenite grain size plays a major role on in-service embrittlement. The fine grain steels with a grain size of ASTM No. 9 or higher are virtually immune to in-service embrittlement. In steels having duplex grain sizes, the embrittlement susceptibility is controlled by the size of coarser grains. For a given steel chemistry, the coarse grain steel is more susceptible to in-service embrittlement, and a decrease in ASTM grain size number from 4 to 0/1 increases the shift in FATT by 61°C (110°F). It is demonstrated that long-term service embrittlement can be simulated, except in very coarse grain steels, by using the extended step-cooling, treatment. The results of step-cooling studies also show that the coarse grain rotor steels take longer time during service to reach a fully embrittled state than the fine grain rotor steels. This difference in the kinetics of embrittlement is believed to be related to the variations in Mo content in the matrix and the grain size of the steels.     

Creep failure by degradation of the microstructure and grain boundary cavitation in a tensile test

For tensile test specimens under constant load creep failure is analysed, based on constitutive relations that account for the nucleation and growth of grain boundary cavities in polycrystalline metals at high temperatures. The material model is formulated in the context of finite strains, so that failure due to loss of cross-sectional area, as well as the possibility of necking, are incorporated in the analysis. Furthermore, the present investigation accounts for the possibility of creep acceleration induced by a gradual degradation of the microstructure. The results include cases in which the three types of failure mechanisms interact, as well as cases where any one of the mechanisms dominate. Most of the investigation is based on a simple one-dimensional model analysis; but a full axisymmetric numerical analysis is used to investigate a few cases, in which necking plays a role.     

Sheath pulling immediately after PTCA: comparison of two different deployment techniques for the hemostatic puncture closure device: a prospective, randomized study

Sheath pulling immediately after percutaneous transluminal coronary angioplasty (PTCA) increases patients' comfort, decreases burden for the medical staff, and may reduce hospital costs by shortening the length of stay. Immediate sheath pulling in anticoagulated patients with a low risk of bleeding complications is feasible using hemostatic devices. For the hemostatic puncture closing device (HPCD), published data regarding sheath pulling in patients immediately after PTCA is limited. Furthermore, no study addressed the question whether the recommended deployment time (DT) of 30 min can be reduced to a few minutes. We, therefore, performed a prospective study, randomizing 140 patients to a DT of 5 and 30 min, respectively. There were no statistical differences in gender, age, height, weight, or cardiovascular risk factors between the two groups. Blood pressures measured invasively immediately before sheath removal were comparable. Activated coagulation time just prior to sheath removal was 227 +/- 52 sec in the DT-5 group and 223 +/- 37 sec in the DT-30 group. After deployment, 74% of the DT-5 patients and 71% of the DT-30 patients showed immediate and complete hemostasis. The remaining patients showed only little oozing with complete hemostasis at the time of the final device removal. Hematoma size after 24 hr was 6.2 +/- 4.4 cm2 for DT-5 and 6.8 +/- 8.2 cm2 for DT-30 patients. There was no statistical difference between both groups. No severe bleeding or major complications were observed in either group. Thus, the use of a collagen system with an intra-arterial anchor (HPCD) is effective and safe when sheaths are pulled immediately after PTCA. The reduction of deployment time from 30 to 5 min is not related to an increased risk of bleeding or other vascular complications; patients can be transferred much faster to the ward, therefore reducing the burden on the personnel in the catheterization laboratory and increasing patients' comfort by allowing them to return to their rooms without a sheath.     

中厚板拉力试样断口宏观形貌及其产生机理分析

随着钢材需求量的日益增加,需方对钢材产品质量要求也越来越高。由于拉伸试样断口的宏观形貌能从一定程度上反映钢材的某些冶金与轧制缺陷,人们对断口的宏观形貌也越来越关注。通过中厚板拉力断口形貌特征的描述及其产生机理的分析,划分出5类常见的不同形貌断口,它有益于力学测试人员的正确判断,有益于工艺的改进,有益公司质量管理和质量判定。