Pharmaceutical therapies for sealing of permeabilized cell membranes in electrical injuries

Several years ago, we proposed that loss of cell membrane structural integrity by electroporation is a substantial cause of tissue necrosis in victims of electrical trauma. Specifically, this involves the permeabilization of the lipid bilayer by thermal and electrical forces. We further suggested that certain mild surfactants in low concentration could induce sealing of permeabilized lipid bilayers and salvage of cells that had not been extensively heat-damaged. Successful restoration of membrane transport properties using the surfactant poloxamer 188 was reported in 1992. The purpose of this study is to further examine the response of electroporated rat skeletal muscle membranes to poloxamer 188 (P188) therapy by direct assay of membrane transport properties. Experimental evidence accumulated to date suggests that P188 is effective in sealing permeabilized cell membranes both in vitro and in vivo.

Dynamics of membrane sealing in transient electropermeabilization of skeletal muscle membranes

Large supraphysiologic transmembrane electrical potentials are known to alter the molecular organization of the bilayer lipid component of cell membranes, leading to ionic permeabilization or "electroporation". Typically, membrane electroporation is followed by several orders of magnitude increases in electrical conductance and diffusive permeability to low-molecular-weight solutes. Electroporation may be transient or stable depending on whether the membrane eventually seals or remains permeabilized. Factors that control sealing have not been well characterized. This paper describes the kinetics of membrane sealing following electroporation by pulses over a range of supraphysiologic potentials. The increase in membrane conductance is highly nonlinear during a -440-mV, 4-ms pulse and reaches two orders of magnitude greater than baseline. Electroporation and relaxation sealing kinetics are quite different, reflecting a significant hysteresis effect. Thus, it appears that the magnitude and duration of the field pulse are important factors in sealing.

The use of collagen-GAG membranes in reconstructive surgery

Porous collagen-glycosaminoglycan (PCG) membranes with a porous silicone elastomer coating have been useful as a scaffold for dermal replacement in burn victims. Critical physicochemical parameters of these membranes include pore size, cross-link density, the percentage of glycosaminoglycan, and the degree of banding of the collagen. These factors govern the immunobiological response. Optimizing these parameters can reduce inflammation, scarring, and contraction of wounds grafted with PCG membranes. PCG membranes are currently commercially manufactured (Integra, Integra Life Sciences, New Jersey) and available for clinical use. Because clinical outcomes have improved using these membranes for burn wound coverage, other skin reconstruction problems including scar resurfacing, keloids, treatment of donor sites, and treatment of chronic wounds can be considered as potential applications. This manuscript illustrates our early experience using Integra as a CG membrane for dermal replacement in reconstructive surgery. Our results indicate that CG membranes can lead to improved compliance and appearance compared to a meshed graft and may be sequentially placed in multiple layers to correct contour deformities. Also, in one case, we observed that, if placed on a wound bed with embedded skin epithelial cells, the PCG promotes epithelialization through the PCG matrix. The use of this material results in a supple integument with many similarities to normal skin.

Curvilinear areas in the perinephric fat seen on MR images

AIM

On magnetic resonance (MR) images, strands correspond to curvilinear areas running in the perinephric fat, and haloes to those lying on the renal surface. Our aim was to examine the diagnostic significance and histopathological basis of these areas.

PATIENTS AND METHODS

MR images obtained in 46 patients without renal disease and 96 patients with renal disease were assessed for the signal intensity and extent of strands and haloes, and their degree of right-left asymmetry.

RESULTS

Strands usually revealed low signal intensity on T1-weighted MR images and high signal intensity on fat-suppressed T2-weighted images and contrast-enhanced fat-suppressed T1-weighted images. Haloes revealed high signal intensity on fat-suppressed T2-weighted images, but most of haloes were not clearly depicted on T1-weighted images or contrast-enhanced fat-suppressed T1-weighted images. Strands and haloes were common and usually symmetrical or only mildly asymmetrical in both patient groups. However, in 11 of the 96 patients with renal disease, prominent strands and/or haloes appeared with remarkable asymmetry and likely represented definite changes in the perinephric fat. At histopathology, vascular loose fibrous tissue was found at the sites of strands and haloes.

CONCLUSION

Strands and haloes usually represent normal anatomical variations. However, the presence of prominent strands or haloes with remarkable right-left asymmetry implies abnormality and may provide additional information in the evaluation of renal disease.

Constitutive activation of the prolactin receptor results in the induction of growth factor-independent proliferation and constitutive activation of signaling molecules

The ability to induce the oncogenic activation of the human prolactin receptor (PRLR) was examined by deleting 178 amino acids of the extracellular ligand-binding domain. Expression of this deletion mutant in the interleukin-3 (IL-3)-dependent murine myeloid cell line 32Dcl3 resulted in the induction of growth factor-independent proliferation. Parental 32Dcl3 cells proliferated only in the presence of exogenous murine IL-3 (mIL-3), while 32Dcl3 cells transfected with the long form of the human PRLR were able to proliferate in response to mIL-3, ovine prolactin, or human PRL. Cells expressing the Delta178 deletion mutant contained numerous phosphotyrosine-containing proteins in the absence of stimulation with either mIL-3 or ovine prolactin. Growth factor stimulation increased the number of proteins phosphorylated and the intensity of phosphorylation. These proteins included constitutively phosphorylated Janus kinase 2, signal transducer and activator of transcription 5, and SHC. Activated extracellular signal-regulated kinases 1 and 2 (ERK1 and ERK2) were observed in unstimulated 32Dcl3 cells expressing the Delta178 mutant. Likewise, transfection of Nb2 cells with the Delta178 deletion mutant induced growth factor-independent proliferation and constitutive activation of Janus kinase 2, ERK1, and ERK2. In addition to the induction of a growth factor-independent state, the expression of the Delta178 deletion mutant also suppressed the apoptosis that occurs when 32Dcl3 cells are cultured in the absence of growth factors such as IL-3. These data suggest that the constitutive activation of the PRLR can be achieved by deletion of the ligand binding domain and that this mutation leads to the oncogenic activation of the receptor as determined by the ability of the receptor to induce growth factor-independent proliferation of factor-dependent hematopoietic cells.

Current approaches to shortage area designation

This paper reviews the various indicators and criteria that are in use to identify rural and urban areas with shortages of primary care physicians, dentists, psychiatrists, or nurses; areas with medically underserved populations; high migrant impact areas; and areas of greatest need/shortage, leading to lists of designated shortage or underserved areas eligible for various federal and state programs; and to lists of areas with priority for resource placement. Presenting these shortage and underservice criteria at a workshop dealing with adequacy was not meant to suggest an equivalency between the concepts of "shortage," "underservice," and "adequacy," but the shortage and underservice criteria can be thought of as a floor on the definition of adequacy, and may contain elements of that definition. Refinements or revisions to the various criteria could probably better identify the needs in rural areas, or the kind of staffing mix needed in various types of areas, or improve priority setting among designated areas; but the existing criteria remain a good first screen to identify those areas with health services-related needs that require further attention.

An independent, inverse association of high-density-lipoprotein-cholesterol concentration with nonadipose body mass

BACKGROUND

Increasing body mass index (BMI) is associated with progressively lower serum HDL-cholesterol concentrations, although the underlying body-composition compartment accounting for this unfavorable lipid change remains uncertain.

OBJECTIVE

Because growing evidence favors a role of lean tissue in HDL homeostasis, the hypothesis was tested that non-adipose tissue components of body mass explain the inverse association of HDL cholesterol and BMI.

DESIGN

Fasting serum lipid concentrations and body composition [total, subcutaneous, and visceral adipose tissue; adipose tissue-free mass (ATFM); and skeletal muscle by whole-body magnetic resonance imaging and body cell mass by 40K counting) were evaluated in healthy adults. Body-composition compartments were expressed as height2-normalized indexes.

RESULTS

An inverse correlation was observed between serum HDL cholesterol and BMI in women (n = 68; R2 = 0.08, P = 0.023) and men (n = 61; R2 = 0.07, P = 0.046). Significant inverse correlations (P = 0.005-0.02) were also observed between HDL cholesterol and nonadipose components (ie, ATFM, skeletal muscle, and body cell mass) but not between HDL cholesterol and any adipose tissue component. The association between HDL cholesterol and ATFM remained significant after serum triacylglycerol was controlled for. When BMI was entered into the HDL cholesterol-ATFM regression model, BMI was not a significant independent variable. The strongest correlate of serum triacylglycerol was visceral adipose tissue (P = 0.002 for both women and men).

CONCLUSIONS

Lean tissues and body cell mass appear to account in part for the long-observed inverse association of HDL cholesterol and BMI. These observations suggest a link between nonadipose tissue compartments and the greater cardiovascular risk associated with high BMI.

Poloxamine 1107 sealing of radiopermeabilized erythrocyte membranes

PURPOSE

Lipid peroxidation-mediated permeabilization of cell membranes following intense ionizing irradiation is well documented. This form of membrane radiopermeabilization leads to rapid exhaustion of cellular high-energy compounds, resulting in the acute onset of cellular necrosis. Strategies to reverse the process of necrosis and preserve cell viability require membrane sealing. This report documents the relative efficacy of Poloxamine 1107, a non-ionic surfactant, compared with other polymers, in sealing radiopermeabilized cell membranes.

MATERIALS AND METHODS

Isolated erythrocytes were exposed to 600 Gy 60Co irradiation at a dose rate of 1.3 Gy/s. Different polymer compounds were added 10 min later to the irradiated cell suspensions. At 2 h later the haemoglobin content in the supernatants was determined spectrophotometrically.

RESULTS

Compared with the non-treated irradiated control, Poloxamine 1107 significantly reduced the leakage of haemoglobin from irradiated erythrocytes. Poloxamer 188 and dextran at equal concentrations had no significant reverse effect on the irradiation-mediated increased membrane permeability. The amount of haemoglobin released from irradiated erythrocytes was inversely related to the Poloxamine 1107 concentration.

CONCLUSIONS

This study demonstrates the capability of Poloxamine 1107 to seal radiopermeabilized cell membranes. Thus, surfactants such as Poloxamine 1107 might be useful as a therapeutic agent in the treatment of high-dose radiation injuries since cellular necrosis due to metabolic exhaustion following radiopermeabilization of their membranes might be prevented.

Preoperative diagnosis of primary fallopian tube carcinoma by magnetic resonance imaging: a case report

Because of the rarity and insidious onset of primary adenocarcinoma of the fallopian tube, early diagnosis is very difficult. Primary fallopian tube carcinoma is also rarely diagnosed preoperatively. This report reviews the value of magnetic resonance imaging (MRI) in aiding the detection of early-stage primary fallopian tube carcinoma in a 48-year-old female. The diagnosis was based on clinical suspicion, elevated CA-125 and MRI. MRI demonstrated the tumor as an area of solid masses with marked enhancement after gadolinium-diethylenetetraaminepentaacetic acid (Gd-DTPA) administration. Primary fallopian tube carcinoma was confirmed by pathologic examination. We hope that, with improvements in imaging, early diagnosis of such a malignant disease could become routinely possible in the future.

Three-dimensional wound surface area calculations with a CAD surface element model

A quadrature scheme is presented for the calculation of three-dimensional (3-D) wound surface area from a 3-D CAD surface element model (SEM) and a two-dimensional (2-D) wound image. The algorithm employs discrete summation over the 2-D wound region with local curvature obtained from the SEM. An approximation is derived for the error due to elemental discretization, and is found to be negligible for the resolution considered here. The alternative method of direct summation over surface element space is shown to result in significant fringe error along the wound boundary.

Uncertainty analysis methods for comparing predictive models and biomarkers: A case study of dietary methyl mercury exposure

Biologically based markers (biomarkers) are currently used to provide information on exposure, health effects, and individual susceptibility to chemical and radiological wastes. However, the development and validation of biomarkers are expensive and time consuming. To determine whether biomarker development and use offer potential improvements to risk models based on predictive relationships or assumed values, we explore the use of uncertainty analysis applied to exposure models for dietary methyl mercury intake. We compare exposure estimates based on self-reported fish intake and measured fish mercury concentrations with biomarker-based exposure estimates (i.e., hair or blood mercury concentrations) using a published data set covering 1 month of exposure. Such a comparison of exposure model predictions allowed estimation of bias and random error associated with each exposure model. From these analyses, both bias and random error were found to be important components of uncertainty regarding biomarker-based exposure estimates, while the diary-based exposure estimate was susceptible to bias. Application of the proposed methods to a simple case study demonstrates their utility in estimating the contribution of population variability and measurement error in specific applications of biomarkers to environmental exposure and risk assessment. Such analyses can guide risk analysts and managers in the appropriate validation, use, and interpretation of exposure biomarker information.

Non-linear microscale alterations in membrane transport by electropermeabilization

The purpose of this study was to quantify the changes in cell membrane conductance in response to electropermeabilization, which may elucidate the mechanisms of tissue injury resulting from high-voltage electrical shock. A high-speed, space-clamp and voltage-clamp experimental configuration was used. The pulse parameters of an imposed transmembrane potential that are instrumental in membrane properties alteration were precisely controlled. The dynamics of the non-linear electroporation response was characterized.

The future of biothermal engineering

This is a report on a three-day workshop held at the Allerton House of the University of Illinois. The first day consisted of invited tutorials on topics related to biothermal engineering: biological structures, analysis of microvascular heat transfer, temperature measurement, cryobiology and cryosurgery, burns, and industrial and consumer applications. The rest of the workshop consisted of discussions in small groups and in plenary sessions dealing with relevant topics. Although the discussions endeavored to be as comprehensive as possible, the specific topics were selected by the participants based on their expertise and interests. The main areas examined were: Instrumentation, Priority applications, Mathematical modeling, Thermal injury. The reliable measurement of the temperature distribution inside the living tissue is still the premier problem of instrumentation although the measurement of other parameters, such as properties, blood perfusion or heat flux, is also of great importance. The most important applications are medical, industrial, consumer, agricultural, space, and military. The degree of sophistication needed in the analysis of specific problems varies a great deal from relatively simple heat conduction models to complicated ones including blood perfusion, anisotropy, and the influence of large blood vessels. For many applications new experimental data are still needed. There have been significant advances in the modeling of living tissue with increasing understanding of its thermal behavior. The consensus was, however, that the models will always have to be tissue or organ specific and some new models are still to be developed.

Dynamic MR imaging of hepatolithiasis

BACKGROUND

To report the dynamic magnetic resonance (MR) imaging findings of hepatolithiasis.

METHODS

Dynamic MR images (fast spoiled gradient echo sequence with intravenous injection of gadopentate dimeglumine) and computed tomography, cholangiography, or angiography of nine patients with hepatolithiasis are analyzed.

RESULTS

All affected hepatic segments showed atrophic changes and contained dilated intrahepatic ducts. These segments showed either iso- or hypointensity on T1-weighted imaging and hyperintensity on T2-weighted imaging. Preferential enhancement was noted throughout all phases of the dynamic study and persisted to delayed T1-weighted imaging in seven patients. In the last two patients, severe atrophic changes made evaluating signal intensity differences and enhancement patterns difficult.

CONCLUSION

In addition to intrahepatic stones and biliary dilatation, segmental atrophy, signal intensity differences, and preferential and persistent enhancement are important MR findings of hepatolithiasis.

MR findings of renin-secreting tumor: a case report

The renin-secreting tumor is a rare benign tumor of the kidney. It is usually detected in young hypertensive patients with high plasma renin activity and hypokalemia. We describe the magnetic resonance findings of a case of renin-secreting tumor of the kidney.

The problem scar

Through deeper understanding of the physiology of wound healing and physico-chemical principles of scarring, biomedical science facilitates the development of new strategies in treatment and prevention of problem scars. It is important for practicing physicians and surgeons to be better aware of the full range of available techniques to control scar formation, and for any medical intervention to be planned in such a way that potential problems are apprehended and minimized or avoided. This article describes the clinical applications of recent research in scar control in order to provide such guidance.

Surfactant administration reduces testicular ischemia-reperfusion injury

PURPOSE

The mechanism of testicular ischemia-reperfusion injury has not been well delineated. We determined the efficacy of a biocompatible surfactant (tetronic 1107) to reduce tissue injury and evaluated cell membrane integrity as reflected by calcium ion permeability in an in vivo animal model of testicular ischemia-reperfusion.

MATERIALS AND METHODS

Three groups of male Sprague-Dawley rats (6 per group) were studied. Group 1 was the nonoperative control, and groups 2 and 3 underwent 4 hours of unilateral testicular ischemia followed by 4 hours of reperfusion. Ten minutes after reperfusion 0.4 ml. saline was administered intravenously to group 2 and 180 mg./kg. surfactant tetronic 1107 to group 3. 99mTechnetium pyrophosphate was used to monitor calcium ion uptake by the ipsilateral and contralateral testicles. Both testicles were also examined histologically.

RESULTS

The surfactant treated animals had markedly diminished hemorrhagic discoloration and vascular congestion compared to saline treated animals. These results were confirmed microscopically with improved nuclear chromicity and disarray of germ cell layers of the seminiferous tubules. The surfactant treated group also had a statistically significant (p <0.05) reduction in radiotracer uptake compared to the saline treated animals, confirming a reduction in calcium ion permeability.

CONCLUSIONS

The results of this study suggest that tetronic 1107 is effective in reducing tissue damage in a testicular ischemia-reperfusion animal model.

Neuropsychological symptom presentation after electrical injury

OBJECTIVE

This study explored the relationship of neuropsychological complaints to accident- and injury-related characteristics, affective state, and work status in a group of electrical injury (EI) patients.

METHODS

Sixty-three EI patients and 22 electricians with no history of electrical shock completed the Neuropsychological Symptom Checklist and the Beck Depression Inventory as part of an extensive neuropsychological evaluation.

RESULTS

The EI group endorsed significantly more physical, cognitive, and emotional symptoms than did the controls. Symptom complaints were not related to injury parameters or litigation status. Only the time interval between injury and assessment accounted for differences in symptom presentation, with patients in the postacute stages of recovery showing the most cognitive and emotional complaints.

CONCLUSION

The neuropsychological syndrome of electrical injury survival includes physical, cognitive, and emotional complaints. Considering that most electrically injured patients are treated within the acute medical setting, greater attention needs to be directed early in the course of treatment toward addressing neuropsychologic and psychiatric issues.

High resistance index of Doppler ultrasound in tuberculous peritonitis presenting as abdominal carcinomatosis: report of two cases

The radiologic features of tuberculous peritonitis (TB peritonitis) are seldom reported, and the use of color Doppler ultrasound in the diagnosis of TB peritonitis is even less common. Herein, we present two patients (a 29-year-old woman and a 56-year-old woman) who were evaluated for months of progressive enlargement of the abdomen, poor appetite and weight loss. In both patients, clinical and laboratory examinations suggested carcinoma, except a very high vascular resistance (resistance index 1.0 and 0.89, respectively) of the tumor feeding vessels detected by color Doppler ultrasound. TB peritonitis was finally diagnosed by exploratory laparotomy. Both patients were treated using a four-drug regimen of isoniazid, rifampicin, ethambutol hydrochloride and pyrazinamide for nine months and were clinically cured. In conclusion, if color Doppler ultrasound reveals normal ovaries, ascites containing thin, delicate incomplete or complete septa, and only a few high-resistance tumor feeding vessels in the abdominal cavity (resistance index > or = 0.80), TB peritonitis should be considered.

Poloxamer 188 enhances functional recovery of lethally heat-shocked fibroblasts

Damage to the cell membrane has been implicated as the primary event in the pathogenesis of heat shock, generally resulting in loss of cellular homeostasis and cell death. Thus a promising mode of therapy would involve the restoration of cell membrane integrity. Surfactant molecules, specifically triblock polymers such as Poloxamer 188 (P-188), possess the ability to self-aggregate into membrane-like structures in aqueous solutions and have been shown to restore membrane integrity. The objective of this study was to develop functional and morphological assays to determine whether treatment with P-188 after heat shock enhances the recovery of thermally damaged cells. Human foreskin fibroblasts were placed in sterile vials and heated by immersion in a calibrated water bath for various lengths of time at predefined temperatures. Cell recovery after heat shock was assessed using a functional assay based on the ability of the cells to contract fibroblast populated collagen lattices (FPCLs). Subsequent to heating, collagen lattices were prepared with control (no heat, no P-188) and heat shocked cells (with and without P-188). Our results indicate that treatment with low concentrations of P-188 after heat shock was effective in ameliorating both the morphological integrity and the contractile function of thermally damaged cells. Further, we observed that P-188 was most effective in improving the contractile ability of cells heat shocked at 45 degrees C; however, it had no influence on the contractility of cells exposed to higher temperatures. Our results suggest that there exists a threshold of thermal stress (45 degrees C for 20-60 min) beyond which treatment with low concentrations of P-188 (0.5 mg/ml) is ineffective in minimizing cell damage. Moreover, the results of our morphological assays indicate that cells treated with P-188 after heat shock maintain their cytoskeletal organization, whereas untreated cells exhibit filamentous actin depolymerization.

Steroid cell tumors of the ovary: clinical, ultrasonic, and MRI diagnosis--a case report

Steroid cell tumors of the ovary are rare sex-cord neoplasms which account for less than 0.1% of all ovarian tumors. They have been divided into two subtypes according to their cell of origin as follows: stromal luteoma, and Leydig cell tumors, and a third subtype with lineage unknown is a steroid cell tumor, not otherwise specified (NOS). The clinical presentation may take many forms, including pain, abdominal distention and bloating, but perhaps the most interesting and noticeable presentations are those related to the hormonal activity and virilizing properties of the tumor. No radiological features of the steroid cell tumor, NOS have been presented in the literature. This report presents the MRI and ultrasonographic findings of a patient having steroid cell tumor, NOS, of the right ovary with metastasis to the uterus.

Normal and variant anatomy of hepatic arteries: angiographic experience

BACKGROUND

Anatomic variation of hepatic arteries is reported to occur in 25-50% of the general population. Knowledge of the existing variations is important in planning and conducting surgical or radiologic procedures in the upper abdomen, such as liver transplantation and transarterial chemo-embolization (TACE).

METHODS

Based on data from 321 patients undergoing upper abdominal arteriography, hepatic artery anatomy was analyzed and classified into three groups (single, double and multiple hepatic arteries at hepatic hilum) according to Suzuki's classification. Each group was subdivided into three types (celiac, mesenteric and mixed types) according to the origin of the hepatic arteries. The variations within each type were recorded.

RESULTS

Two hundred and sixty one patients (68.%) had single hepatic arteries. One hundred and five patients (27.6%) had double hepatic arteries and only fifteen patients had multiple hepatic arteries. All of these variants, including twenty subtypes, were identified.

CONCLUSIONS

This study, based on Suzuki's classification, provides basic data for the anatomic variations of hepatic arteries for the Chinese population in Taiwan.