Stimulation of single isolated adult ventricular myocytes within a low volume using a planar microelectrode array.
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Microchannels (40- microm wide, 10- microm high, 10-mm long, 70- microm pitch) were patterned in the silicone elastomer, polydimethylsiloxane on a microscope coverslip base. Integrated within each microchamber were individually addressable stimulation electrodes (40- microm wide, 20- microm long, 100-nm thick) and a common central pseudo-reference electrode (60- microm wide, 500- microm long, 100-nm thick). Isolated rabbit ventricular myocytes were introduced into the chamber by micropipetting and subsequently capped with a layer of mineral oil, thus creating limited volumes of saline around individual myocytes that could be varied from 5 nL to 100 pL. Excitation contraction coupling was studied by monitoring myocyte shortening and intracellular Ca(2+) transients (using Fluo-3 fluorescence). The amplitude of stimulated myocyte shortening and Ca(2+) transients remained constant for 90 min in the larger volume (5 nL) configuration, although the shortening (but not the Ca(2+) transient) amplitude gradually decreased to 20% of control within 60 min in the low volume (100 pL) arrangement. These studies indicate a lower limit for the extracellular volume required to stimulate isolated adult cardiac myocytes. Whereas this arrangement could be used to create a screening assay for drugs, individual microchannels (100 pL) can also be used to study the effects of limited extracellular volume on the contractility of single cardiac myocytes. (+info)
DYSPHONIA DUE TO UNILATERAL NERVE PARALYSIS. TREATMENT BY THE INTRACORDAL INJECTION OF SYNTHETICS--A PRELIMINARY REPORT.
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The injection treatment of unilateral recurrent vocal cord nerve paralysis, successfully performed 40 years ago with paraffin, has recently been reintroduced with non-reactive synthetics. Improvement in the voice far and above that which can be achieved by voice therapy or any practicable surgical procedure has been demonstrated by several investigators. The technique is relatively simple, and there are no significant untoward reactions. Judging from experimental and clinical studies with these inert materials when introduced into other parts of the body, adverse long range effects are not likely to occur in the larynx. Eleven of 12 patients treated by injection of silicone or Teflon paste had substantial improvement in vocal quality and strength. Silicone was absorbed slowly from the injection site and the improvement was not enduring; when Teflon was used, it stayed at the site and the improvement was sustained. (+info)
Comparison of velocity profiles for different flow chamber designs used in studies of microbial adhesion to surfaces.
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Flow chambers are commonly used to study microbial adhesion to surfaces under environmentally relevant hydrodynamic conditions. The parallel plate flow chamber (PPFC) is the most common design, and mass transport occurs through slow convective diffusion. In this study, we analyzed four different PPFCs to determine whether the expected hydrodynamic conditions, which control both mass transport and detachment forces, are actually achieved. Furthermore, the different PPFCs were critically evaluated based on the size of the area where the velocity profile was established and constant with a range of flow rates, indicating that valid observations could be made. Velocity profiles in the different chambers were calculated by using a numerical simulation model based on the finite element method and were found to coincide with the profiles measured by particle image velocimetry. Environmentally relevant shear rates between 0 and 10,000 s(-1) could be measured over a sizeable proportion of the substratum surface for only two of the four PPFCs. Two models appeared to be flawed in the design of their inlets and outlets and allowed development of a stable velocity profile only for shear rates up to 0.5 and 500 s(-1). For these PPFCs the inlet and outlet were curved, and the modeled shear rates deviated from the calculated shear rates by up to 75%. We concluded that PPFCs used for studies of microbial adhesion to surfaces should be designed so that their inlets and outlets are in line with the flow channel. Alternatively, the channel length should be increased to allow a greater length for the establishment of the desired hydrodynamic conditions. (+info)
Image-guided resection of cerebral cavernous malformations.
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OBJECTIVE: To evaluate retrospectively the effectiveness of image-guided navigation techniques in the management of cerebral CMs. METHODS: Between July 1997 and January 2001, 44 patients underwent image-guided resection of cerebral CMs. To counteract brain shift, a small silicon catheter was implanted as a guide in the case of deep-seated lesions (except in the case of brain stem CMs) and before excision of multiple lesions. RESULTS: A total of 27 men and 17 women with a mean age of 35 years underwent surgical procedures (5 patients had multiple lesions). The lesions were located in the frontal (n = 14), lobe temporal lobe (n = 12), parietal lobe (n = 6), cerebellum (n = 6), thalamus (n = 5), pons (n = 5), and orbital region (n = 1). Under the guidance of a StealthStation navigator, total removal of the lesions was achieved in all patients. Follow-up revealed marked improvement of preoperative symptoms in 26 patients and no additional deficits in 13 patients. Five patients suffered from additional neurological deficits, but two of them gradually improved during the follow-up period. CONCLUSIONS: With the assistance of an image-guided surgical system, functional areas can be effectively avoided and surgical injury can be decreased. This system is well suited for accurate localization and safe resection of small, deep-seated CMs. (+info)
A study to compare a new self-adherent soft silicone dressing with a self-adherent polymer dressing in stage II pressure ulcers.
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Pressure ulcers are common among elderly nursing home residents. To be effective in managing these wounds, a dressing should maintain a moist environment, facilitate healing, absorb exudate, remain in place for a number of days, and prevent trauma to the surrounding skin. An 8-week, open, randomized, multicenter, controlled study was conducted to compare the effects of a new self-adherent soft silicone dressing and a self-adherent hydropolymer dressing on Stage II pressure ulcers. Thirty-eight (38) residents participated in the study. Eighteen residents (mean age 83.8 years, range 74.9 to 95.1 years) were randomized to wound management with a soft silicone dressing, and the ulcers of 20 residents (mean age 82.5 years, range 66.4 to 91.9 years) were managed with a hydropolymer dressing. Wound healing, wound and surrounding skin characteristics, and ease of dressing removal were measured and documented. During the study, eight (44%) ulcers in the soft silicone group and 10 (50%) in the hydropolymer dressing group healed. Both dressings were changed approximately once a week and no differences in signs of inflammation, amount of exudate and odor, or incidence of leakage were observed. Damage to the surrounding skin, maceration, and dressing removal difficulties were less common with the soft silicone dressing. Differences in tissue damage between the two dressings were significant during weeks 1, 2, and 3 (P < 0.05). Studies with a larger sample size are needed to confirm these findings. (+info)
Laparoscopic adjustable silicone gastric banding versus vertical banded gastroplasty in morbidly obese patients: a prospective randomized controlled clinical trial.
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OBJECTIVE: To compare, in a prospective, randomized, single-institution trial laparoscopic adjustable silicone gastric banding (LASGB) with laparoscopic vertical banded gastroplasty (LVBG) in morbidly obese patients. SUMMARY BACKGROUND DATA: LASGB is a simple and safe procedure, but some reports have suggested disappointing long-term results. Despite the recent widespread use of LASGB, there are no prospective nor randomized trials comparing LASGB with other laparoscopic procedures. METHODS: A total of 100 morbidly obese patients, with body mass index (BMI) 40 to 50 kg/m2, without compulsive eating, were randomized to either LASGB (n = 49) or LVBG (n = 51). Minimum follow-up was 2 years (mean 33.1 months). RESULTS: There were no deaths or conversions in either group. Mean operative time was 94.2 minutes in LVBGs and 65.4 in LASGBs (P < 0.05). Early morbidity rate was lower in LASGBs (6.1%) versus LVBGs (9.8%) (P = 0.754). Mean hospital stay was shorter in LASGBs versus LVBGs: 3.7 days versus 6.6 (P < 0.05). Late complications rate in LVBGs was 14% (7 of 50) and in LASGBs 32.7% (16 of 49) (P < 0.05). The most frequent complication was the slippage of the band (18%). Late reoperations rate in LVBGs was 0% (0 of 50) versus 24.5% (12 of 49) in LASGBs (P < 0.001). Excess weight loss in LVBGs was, at 2 years, 63.5% and, at 3 years, 58.9%; in LASGBs, excess weight loss, respectively, was 41.4% and 39%. BMI in LVBGs was, at 2 years, 29.7 kg/m2 and, at 3 years, 30.7 kg/m2; in LASGBs, BMI was 34.8 kg/m2 at 2 years and 35.7 kg/m2 at 3 years. According to Reinhold's classification, a residual excess weight <50% was achieved, at 2 years, in 74% of LVBG and 35% of LASGB (P < 0.001). CONCLUSIONS: This study demonstrates that, in patients with BMI 40 to 50 kg/m2, LASGB requires shorter operative time and hospital stay but LVBG is more effective in terms of late complications, reoperations, and weight loss. (+info)
An evaluation of an adhesive hydrocellular foam dressing and a self-adherent soft silicone foam dressing in a nursing home setting.
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To assess the performance of two wound dressings in the management of chronic wounds, a 5-year retrospective descriptive study was conducted involving 4,200 wounds in 1,891 residents of 30 nursing homes in the state of Florida. Wound and patient variables were abstracted from charts completed by the wound care clinicians providing care in the nursing homes. The chart abstraction time period was chosen to capture a change in wound dressing regimens in these nursing homes. Patient demographic and wound assessment variables, including evidence of surrounding skin stripping information, were abstracted from the database. The majority of wounds were classified as pressure ulcers (3,579 out of 3,795 [94%] hydrocellular-dressing treated wounds; 339 of 352 [96%] silicone dressing-treated wounds, and 51 of wounds managed with both dressings). The majority of wounds were classified as Stage II or III ulcers. Wounds in the hydrocellular group were larger (mean area 7.53 cm2) and took longer to heal (mean 70.1 days) than those in the silicone dressing group (mean area 5.5 cm2, 39.2 days) but the proportion of ulcers healed was the same (63%) in both groups. Skin stripping was rare with either dressing (1% to 2% of wounds). Problems with adhesion and infections occurred more frequently in the silicone dressing group than in the hydrocellular dressing group. The results of this study show that most chronic wounds managed with either dressing will heal after an average of 70 days, that differences between the two dressings are minimal, and that periwound skin stripping is uncommon. Ease of use characteristics and the ability of dressings to remain in place appeared to differ, possibly affecting infection rates and costs of care. (+info)
Risk factors of acute endophthalmitis after cataract extraction: a case-control study in Asian eyes.
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AIM: To describe risk factors of acute endophthalmitis after cataract extraction in an Asian population. METHODS: A retrospective, case-control study. Cases (n = 34) were patients with acute endophthalmitis presenting within 6 weeks after cataract surgery. Three controls per case (n = 102) were randomly selected from the cataract surgery list matched on the date of operation of cases. RESULTS: Few risk factors were identified. In multivariable analysis, endophthalmitis was associated with silicone intraocular lens (odds ratio 5.1, 95% confidence intervals, 1.2 to 21.6, compared to poly(methylmethacrylate) lens) and posterior capsular rupture during surgery (odds ratio 20.9, 95% confidence intervals 2.3 to 187.9). CONCLUSION: Silicone intraocular lens and rupture of the posterior capsule are risk factors of acute endophthalmitis after cataract surgery. (+info)