Biomedical subjects

W S Kim

Publications and source records attributed to W S Kim.

At least 91 records · Page 5Linked to original sources

PubMed2000

Late abnormal findings on high-resolution computed tomography after Mycoplasma pneumonia.

BACKGROUND: The clinical course of Mycoplasma pneumonia is typically mild and self-limited. There are, however, several case reports of severe complication following this illness with considerable morbidity and mortality. OBJECTIVES: This study was conducted to investigate, using high-resolution computed tomography (HRCT), the long-term pulmonary structural abnormalities after Mycoplasma pneumonia and to identify risk factors (chest radiograph findings, antibody titers, and host factors) that might increase the likelihood of developing the sequelae. METHODS: Thirty-eight children requiring hospitalization attributable to Mycoplasma pneumonia were recruited by the retrospective examination of hospital records. They underwent HRCT after an interval of 1.0 to 2. 2 years. A control group of 17 children with the history of Mycoplasma upper respiratory infection was also studied after a similar interval. RESULTS: Abnormal HRCT findings were present in 37% (14/38) of the pneumonia group, compared with 12% (2/17) of the control group. The abnormalities in the pneumonia group, which appeared alone or in combination, included mosaic perfusion (n = 12), bronchiectasis (n = 8), bronchial wall thickening (n = 4), decreased vascularity (n = 1), and air trapping on expiratory scan (9 of 29 tested). The area affected by these abnormalities, usually involving 2 or more lobes, corresponded in all cases to the location of the infiltrate on chest radiograph at the time of pneumonia. Between subjects with abnormal HRCT (n = 14) and normal HRCT (n = 24) in the pneumonia group, significant differences were observed in age at the time of pneumonia (mean +/- standard deviation: 5.3 +/- 2. 0 years vs 7.7 +/- 3.4 years) and peak antimycoplasma antibody titer (geometric mean [range of 1 standard deviation]; 1:7943 [3126-19 953] vs 1:3093 [832-11 482]). CONCLUSIONS: We conclude that a considerable proportion of children with history of Mycoplasma pneumonia have abnormal findings on HRCT, suggestive of small airway obstruction and that younger age and higher antibody titer at the time of pneumonia may be risk factors for these sequelae.

Antibodies, Bacterial↗

PubMed2000

Cloning of a cDNA encoding cathepsin D from salamander, Hynobius leechii, and its expression in the limb regenerates.

Cathepsin D is a major lysosomal aspartic proteinase participating in the degradation or modification of intra- and extracellular matrix molecules, and its activity is known to increase in the process of tissue reorganization during the early phase of salamander limb regeneration. Here, we report the cloning of a salamander cathepsin D cDNA from Hynobius leechii and its expression profile in normal and retinoic acid (RA) treated limb regenerates. The gene expression of cathepsin D increased notably during the dedifferentiation stage and decreased gradually thereafter. Furthermore, RA that enhances dedifferentiation of regenerating salamander limb caused the elevation of cathepsin D expression both in terms of level and duration. These results suggest that cathepsin D plays important role(s) in the dedifferentiation process, and enhancement of cathepsin D expression might be closely related to RA-evoked pattern duplication.

Amino Acid Sequence↗

PubMed2000

Glucose transporter 1 (GLUT1) expression is associated with intestinal type of gastric carcinoma.

Increased expression of glucose transporter1 (GLUT1) has been reported in many human cancers. We hypothesized that the degree of GLUT1 might provide a useful biological information in gastric adenocarcinoma. RT-PCR and immunostaining were used to analyze GLUT1 expression in gastric cancer. RT-PCR showed GLUT1 expression was not largely detected in normal gastric tissue but was detected in cancerous gastric tissue of counterpart. By immunohistochemistry, GLUT1 protein was absent in normal gastric epithelium and intestinal metaplasia. 11 of 65 patients with gastric adenocarcinoma had specific GLUT1 immunostaining in a plasma membrane pattern with varied intensities. GLUT1 protein did not show any significant correlation with tumor stage and nodal metastasis (p>0.05 by Mann-Whitney test). However, the positive immunostaining for GLUT1 is associated with intestinal differentiation (p=0.003). Our results suggest that GLUT1 protein is associated with intestinal type of gastric cancer.

Adenocarcinoma↗

PubMed2000

Colorectal adenocarcinoma as a second malignant neoplasm following rhabdomyosarcoma of the urinary bladder: a case report.

Following improvements in therapy for childhood malignancies, the striking increase in survival rate over the past 30 years has led to the increase risk of developing second malignant neoplasms (SMNs). We report a case of colorectal carcinoma as a SMN, following treatment for rhabdomyosarcoma. The patient was diagnosed with rhabdomyosarcoma of the urinary bladder at his age of three years, and developed adenocarcinoma in the colon 13 years later. Histologic examination of the surgical specimen revealed adenocarcinoma involving the rectosigmoid area with radiation colitis in its background. The tumor cells showed strong immunoreactivity for p53 protein, suggesting the role of irradiation and p53 mutation in carcinogenesis. This case emphasizes the need for dose observation in survivors of early childhood malignancies treated with radiation and multiagent chemotherapy.

Adenocarcinoma↗

PubMed2000

Survival of Pseudomonas fluorescens and Salmonella typhimurium after electron beam and gamma irradiation of refrigerated beef.

The radurization effects of gamma ray and electron beam irradiation at 1.5 and 3.0 kGy on beef steaks inoculated with Salmonella Typhimurium and Pseudomonas fluorescens were investigated during 8 days of storage at 5 degrees C. Total bacterial counts and numbers of Salmonella Typhimurium and P. fluorescens were analyzed at 2-day intervals. Total bacterial counts of samples irradiated by both gamma rays and electron beam were significantly (P < 0.05) reduced by 3.8 to 5.3 log CFU/g. Salmonella Typhimurium was not detectable during the experimental period. P. fluorescens counts of beef samples irradiated by gamma rays at both 1.5 and 3.0 kGy were not detected; however, P. fluorescens in samples irradiated by electron beam at 1.5 and 3.0 kGy was recovered after 2 days, and bacterial counts reached 7.8 and 6.9 log CFU/g, respectively. Both gamma ray and electron beam irradiation reduced total bacterial counts initially, possibly extending shelf life. Irradiation was very effective in destroying Salmonella Typhimurium; however, P. fluorescens was not completely eliminated by electron beam irradiation. Consequently, gamma ray irradiation was more effective than electron beam irradiation in the destruction of P. fluorescens.

Animals↗

PubMed2000

Transperineal ultrasonography in imperforate anus: identification of the internal fistula.

The purpose of this study was to assess the usefulness of transperineal ultrasonography in identifying the internal fistula in cases of imperforate anus. Transperineal ultrasonography was performed in 19 infants (13 neonates and 6 older infants; 13 were male and 6 were female) with imperforate anus to identify the internal fistula. Sagittal plane images were obtained through the anal dimple, and the internal connection of the rectal fistula was traced. The ultrasonographically traced internal fistula was compared with that observed on distal loopography after colostomy or with surgical findings. The internal fistula was identified as a hypoechoic linear tract, containing linear echogenicity in some cases. Of 19 patients, internal fistulas were correctly identified in 16 patients; these were rectourethral (n = 12), rectovaginal (n = 1), rectovestibular (n = 1), rectovesical (n = 1), and rectocloacal (n = 1). In three patients, internal fistulas were incorrectly defined; these cases consisted of rectovestibular (n = 2) and rectovaginal (n = 1) fistulas. Internal fistulas were correctly identified in all of the 13 male patients and in 3 of 6 female patients. Transperineal ultrasonography is an excellent diagnostic modality to define the type of the internal fistula in imperforate anus.

Anus, Imperforate↗

PubMed2000

The value of interleukin-12 as an activity marker of pulmonary sarcoidosis.

BACKGROUND: Sarcoidosis is characterized by hyperactivity of T-helper lymphocytes and recent studies showed that they were mainly Th1 cells. IL-12 is a major cytokine inducing Th1 differentiation of naive T cells. This study was performed to test whether IL-12 can be a marker for disease activity and possibly a prognosis in sarcoidosis. METHODS: IL-12 levels of BALF (BALF-IL-12) and conditioned medium of alveolar macrophages (AM) were measured by ELISA in 36 patients with pulmonary sarcoidosis (14 males and 22 females, mean age: 39.6 +/- 11.0 years) and eleven normal controls. Clinically, 16 patients had active sarcoidosis and 20 had an inactive disease. RESULTS: BALF-IL-12 of sarcoidosis patients (41.3 +/- 43.9 pg/ml) was significantly higher than that of normal controls (2.5 +/- 0.4 pg/ml) (p < 0.001). The patients with active disease (71.3 +/- 54.3 pg/ml) had a higher BAL-IL-12 level than those with inactive disease (17.3 +/- 13.8 pg/ml) (p = 0.0001). It had a significant correlation with the number of T4 cells (p = 0.0001), total cell number, number and percentage of lymphocytes (p = 0.0001) and AM (p = 0.001) in BALF. It was also significantly correlated with soluble ICAM-1 levels in serum (p = 0.0001) and BALF (p = 0.002), and ICAM-1 expression of AM (p = 0.001). Furthermore the patients whose condition worsened without therapy had a significantly higher initial BALF-IL-12 level than the patients whose condition improved spontaneously. The AM of sarcoidosis secreted significantly more IL-12 (133 +/- 177 pg/ml) than AM of controls (68.3 +/- 43.7 pg/ml) (p = 0.038). CONCLUSION: Our data suggest that the BALF-IL-12 level can be used as a marker of the activity of pulmonary sarcoidosis and possibly prognosis.

Adult↗

PubMed1999

Modulation of gelatinase activity correlates with the dedifferentiation profile of regenerating salamander limbs.

Remodeling of extracellular matrix (ECM) is one of the key events in many developmental processes. In the present study, a temporal profile of gelatinase activities in regenerating salamander limbs was examined zymographically. In addition, the effect of retinoic acid (RA) on these enzyme activities was examined to relate the pattern-duplicating effect of RA in limb regenerates with gelatinase activities. During regeneration, various types of gelatinase activities were detected, and these activities were at their maximum levels at the dedifferentiation stage. Upon treatment with chelating agents EDTA and 1,10-phenanthroline, the enzyme activities were inhibited indicating that those enzymes are likely matrix metalloproteinases (MMPs). Considering the molecular sizes and the decrease of molecular sizes by treatment with p-aminophenylmercuric acetate, an artificial activator of proMMP, some of the gelatinases expressed during limb regeneration are presumed to be MMP-2 and MMP-9. In RA-treated regenerates, overall gelatinase activities increased, especially the MMP-2-like gelatinase activity which increased markedly. These results suggest that MMP-2-like and MMP-9-like gelatinases play a role in ECM remodeling during regeneration, and that gelatinases are involved in the excessive dedifferentiation after RA treatment.

Ambystoma mexicanum↗

PubMed1999

Differentiation of Lactococcus lactis subspecies lactis and subspecies cremoris strains by their adaptive response to stresses.

Lactococcus lactis subspecies lactis (L. lactis ssp. lactis) and Lactococcus lactis subspecies cremoris (L. lactis ssp. cremoris) were investigated in respect to their response to acid, bile-salt and freezing stresses. First, the sublethal and lethal levels of each stress were determined for both subspecies. For acid stress, the levels were pH 4.5 and 2.5, respectively, for L. lactis ssp. lactis, and pH 5.0 and 3.0, respectively, for L. lactis ssp. cremoris. For bile-salt stress, the levels were 0.03 and 0.1%, respectively, for L. lactis ssp. lactis, and 0.01 and 0.04%, respectively, for L. lactis ssp. cremoris. For freezing stress, 10 degrees C was used as the sublethal temperature and -20 degrees C was used as the lethal temperature for both subspecies. To evaluate the effect of each stress at log phase, a log-phase culture was challenged directly with the appropriate lethal level (control culture) and a second log-phase culture was pre-exposed to the appropriate sublethal level prior to testing survival under normally lethal conditions (test culture). Some, if not most, of the cells were killed in the control cultures for all three stresses. However, in the test cultures, the viability was significantly improved for all of the L. lactis ssp. lactis strains tested, but not for the L. lactis ssp. cremoris strains. It appears, therefore, that L. lactis ssp. lactis is capable of displaying adaptive response to stresses, whereas L. lactis ssp. cremoris seems to lack this phenotype or the response is much weaker in this subspecies. The effect of each stress on stationary-phase cultures was also investigated. Unlike the log-phase cultures, the stationary-phase cultures of both subspecies, challenged directly with the lethal levels, were highly resistant to each of the three stresses tested.

Adaptation, Physiological↗

PubMed1999

Distribution of carcinoembryonic antigen and biologic behavior in colorectal carcinoma.

PURPOSE: Carcinoembryonic antigen is assumed from the results of several experiments to be associated with invasion of colorectal carcinoma by adhesion or contact inhibition. The patterns and the intensity of carcinoembryonic antigen distribution in colorectal carcinoma were assessed to verify whether they were correlated with malignant potential from those biologic characteristics. METHODS: Carcinoembryonic antigen distribution was tested in the archival samples of 149 colorectal carcinomas by immunohistochemistry, using three characterized anti-carcinoembryonic antigen monoclonal antibodies: T84.66, PR1A3, and PR3B10. The distribution patterns in neoplastic tissue were categorized into unstained, apicoluminal, and diffuse cytoplasmic patterns. Tumor, invasive tumor margin, and tissue surrounding the tumor were examined. RESULTS: Although all three antibodies revealed a positive correlation, T84.66 showed better discrimination than the others. Although none of the negative staining of the tumor or invasive tumor margin showed recurrence, the apicoluminal pattern showed recurrence, and the diffuse pattern showed the most frequent recurrence (P < 0.01). Recurrence was also associated with staining intensity in the apicoluminal pattern in both the tumor and invasive tumor margin (P < 0.05). Infiltrative tumor growth and lymph node metastasis were more frequent in cases of positive staining in tissue surrounding the tumor. Patients with the apicoluminal pattern achieved longer survival than patients with the diffuse-cytoplasmic pattern in the invasive tumor margin (P = 0.024) by a multivariate analysis including tumor stage and histologic differentiation. CONCLUSION: The distribution of carcinoembryonic antigen in tumors and surrounding tissue seems to be closely correlated with invasiveness and metastatic behavior in colorectal carcinoma. Carcinoembryonic antigen immune staining can be considered as an efficient tool to determine groups with risk of recurrence.

Adenocarcinoma↗

PubMed1999

Complicated pleural tuberculosis in children: CT evaluation.

PURPOSE: To describe the CT features of complicated pleural tuberculosis in children and to define the use of CT in children with pleural tuberculosis. MATERIALS AND METHODS: The CT findings in 11 children with complicated pleural tuberculosis were retrospectively analysed. CT was performed to evaluate persistent pleural thickening (n = 6) or a mass-like lesion (n = 5) detected on plain radiographs. Chest radiographs and medical records were reviewed to determine whether additional information provided by CT had altered clinical management. RESULTS: On CT, more than one location was involved in five patients (45%) and in two patients (18%) the entire pleural spaces were involved. Pleural thickening was seen in all 11 patients and enhancement after administration of contrast medium occurred in ten patients (91%). Low-density fluid collections were seen in nine patients (82%) and in two, CT revealed fluid collections within calcified pleural lesions. In five patients with mass-like lesions on plain radiographs, CT showed a low-density pleural mass with peripheral enhancement in four and a calcified pleural mass with fluid collection in one. CT demonstrated parenchymal abnormalities on the same side as pleural lesions in all 11 patients and hilar or mediastinal adenopathy in four. Four patients (36%) underwent surgery because of fluid within a calcified fibrothorax (n = 3) and chest wall tuberculosis (n = 1) that were seen only on CT. CONCLUSIONS: The CT features of complicated pleural tuberculosis in children were pleural thickening, enhancement and fluid collection with associated parenchymal abnormalities and lymphadenopathy. In the evaluation of children with pleural tuberculosis, CT can be useful for demonstrating fluid within a calcified fibrothorax or chest wall involvement, which usually requires surgical intervention.

Adolescent↗

PubMed1999

Abdominal-wall myositis secondary to intra-arterial chemotherapy for femoral osteosarcoma.

With the increasing application of intra-arterial chemotherapy (IAC), new side-effects are encountered. We describe two children with proximal femoral osteosarcoma who developed focal myositis of the abdominal wall musculature after IAC. In both cases, myositis presented as abdominal pain and mimicked acute abdomen. US demonstrated asymmetrical thickening of abdominal-wall musculature in the right lower abdomen. This diagnosis should be considered when evaluating the patient with unexplained abdominal pain and a history of IAC.

Abdominal Muscles↗

PubMed1999

Change in corneal sensitivity following laser in situ keratomileusis.

PURPOSE: To evaluate the change in corneal sensitivity following laser in situ keratomileusis (LASIK). SETTING: Department of Ophthalmology, Maryknoll Hospital, Pusan, Korea. METHODS: The corneal sensitivity in 40 eyes (32 patients) was measured before and 1 and 2 weeks and 1, 3, and 6 months after LASIK. Sensitivity measurements were made with an esthesiometer at central, temporal, inferior, nasal, and superior points on the corneal flap. The eyes were grouped by ablation depth: Group 1, corneal ablation depth less than 100 microns; Group 2, corneal ablation depth more than 100 microns. RESULTS: Corneal sensitivity did not recover to the preoperative level by 6 months after LASIK. Except at the hinge of the corneal flap, the pattern of sensitivity recovery was similar among the various points. Recovery was more rapid at the hinge than at other areas (P < .05). There was a trend toward a greater reduction in corneal sensitivity in Group 2, the group with deeper ablations, than in Group 1. CONCLUSION: The results suggest that lamellar cutting of the cornea during LASIK impairs corneal sensitivity and that the depth of the corneal ablation affects the extent of corneal sensitivity loss and recovery.

Adult↗

PubMed1999

Respiratory and haemodynamic effects of the prone position at two different levels of PEEP in a canine acute lung injury model.

This study was designed to examine whether the oxygenation response in the prone position differs in magnitude depending on the level of positive end-expiratory pressure (PEEP) applied in the supine position, and whether cardiac output (CO) increases in the prone position. In seven supine dogs, acute lung injury was established by saline lavage (arterial oxygen tension (Pa,O2)/inspiratory oxygen fraction (FI,O2) 17.8+/-9.6 kPa (134+/-72 mmHg)), and inflection point (Pflex) of the respiratory system was measured (6.6+/-1.4 cmH2O). Pa,O2/FI,O2 and CO of the supine and prone positions were obtained under the application of low PEEP and then under optimal PEEP (2 cmH2O below and above Pflex, respectively). The net increase in Pa,O2/FI,O2 by prone positioning was greater at low PEEP (27.3+/-12.0 kPa (205+/-90 mmHg)) than at optimal PEEP (4.4+/-13.0 kPa (33+/-98 mmHg)) (p=0.006). CO decreased significantly with optimal PEEP in the supine position (2.4+/-0.5 versus 3.1+/-0.4 L x min(-1) at baseline, p<0.001), and increased to 3.4+/-0.6 and 3.6+/-0.7 L x min(-1) in the prone position at 5 min and 30 min, respectively (both p=0.018). When the dogs were turned supine at optimal PEEP, CO again decreased (2.4+/-0.5 L x min(-1), p<0.001). In conclusion, the prone position augmented the effect of relatively low positive end-expiratory pressure on oxygenation, and attenuated the haemodynamic impairment of relatively high positive end-expiratory pressure in a canine acute lung injury model.

Animals↗

PubMed1999

Heat shock response decreases endotoxin-induced acute lung injury in rats.

OBJECTIVE: Transient whole-body hyperthermia was reported to reduce lung damage in a rat with intra-abdominal sepsis produced by caecal perforation. METHODOLOGY: In order to determine the effect of heat shock response on acute lung injury induced by endotoxin, which plays a central role in the pathogenesis of sepsis, we instilled either saline or lipopolysaccharide (LPS) intravenously with and without heat pretreatment in rats. The heated rats had their rectal temperature raised to more than 40 degrees C for 13 min 18 h before intravenous administration of saline or LPS. RESULTS: We found that the lung leak was significantly increased among the rats given LPS intravenously with (median, 0.17; range, 0.15-0.22; n = 10) and without heat pretreatment (0.23; 0.17-0.30; n = 10) compared with those of saline-treated rats (0.13; 0.10-0.14; n = 10) (P < 0.05 in each). However, rats given LPS after heat pretreatment had significantly decreased lung leak index compared with those of LPS-treated rats without heat pretreatment (P < 0.05). Rats administered LPS intravenously showed increased myeloperoxidase activity without heat pretreatment (19.01; 9.34-28.00 U/g; n = 10) compared with that of saline-treated rats (7.09; 4.49-10.56 U/g; n = 5) (P < 0.05) (Fig. 2). Myeloperoxidase activity of the rats treated with LPS with heat pretreatment (5.57; 2.87-8.96 U/g; n = 10) was significantly decreased to the level of normal control compared with that of LPS-treated rats without heat pretreatment (P < 0.05). The levels of heat shock proteins (HSP72) in lung tissue, which were examined by western blot analysis, were increased over baseline levels at 23 h after hyperthermic stress. CONCLUSIONS: These observations show that brief heat shock response is associated with the induction of HSP72 protein synthesis and attenuated neutrophil recruitment and acute lung leak is induced by endotoxin in rats.

Acute Disease↗

PubMed1999

Short-term effects of a new intravascular nitinol stent in canine arteries.

RATIONALE AND OBJECTIVES: To evaluate the short-term effects of a new nitinol stent on canine arteries. METHODS: Eighteen nitinol mesh stents were placed in abdominal aortas, common iliac arteries, and renal arteries of six dogs. Angiography was performed to evaluate the patency rates and structural changes of arteries at 1 day, 3 weeks, 4 weeks, and 10 weeks after stent insertion. Gross and light microscopic examinations were performed after angiography. RESULTS: On angiography, the patency rate was 100%, and no thrombosis was observed. All side branches from stented segments were patent. The mean neointimal thickness over and between stent wires was 94 and 167 microns. No difference was found between the aorta and the small vessels. Histologically, the neointima was covered with endothelium and was composed of subintimal fibrosis with mild inflammation. CONCLUSIONS: The new type of nitinol mesh stent showed a high patency rate, with no thrombosis and relatively thin neointimal proliferation.

Alloys↗

PubMed1999

Properties of coralline hydroxyapatite and expanded polytetrafluoroethylene membrane in the immature craniofacial skeleton.

Although extensive research regarding the treatment of calvarial defects has been done in adult models, little is known about the response in the maturing skeleton. The role of coralline hydroxyapatite and expanded polytetrafluoroethylene membrane in augmenting bone growth and repair of calvarial defects in a neonatal model is explored. Utilizing a 3-week-old neonatal swine model, bone growth into 28 calvarial defects was measured. After exposure of the calvaria in seven animals, four defects of 10 mm in diameter were created. In each animal, one defect was treated with a 10-mm disc of porous hydroxyapatite alone (Interpore 500, Interpore International), and a second defect was covered with an expanded polytetrafluoroethylene membrane (Gore-Tex OV-6) secured by four 3-mm microscrews (Luhr Microsystem, Howe-Medica Inc.). The third defect combined an implanted hydroxyapatite disc covered by an expanded polytetrafluoroethylene membrane, whereas the fourth defect served as an untreated control. Histology and histomorphometry were performed on undecalcified specimens harvested at 6 weeks after surgery. In both hydroxyapatite groups, the bone growth into the inorganic matrix provided complete osseous union in all specimens, and the amount of fibrosis was significantly lower (p < 0.02) in comparison with the control. Unexpectedly, there was significant osteoclastic resorption of the hydroxyapatite matrix (35.1 percent decrease) with simultaneous bone deposition and remodeling. The addition of an expanded polytetrafluoroethylene membrane covering the hydroxyapatite implant provided an insignificant advantage in bone growth (27.3 percent versus 28.3 percent, respectively). Finally, the expanded polytetrafluoroethylene membrane alone afforded no qualitative advantage secondary to intrusion of brain and dura into the defect as well as displacement of the membrane inward during appositional growth, leading to incomplete healing of the defect with thinning of the surrounding cranial bone. Unique in this maturing model was morphologic evidence of complete union at the calvaria-hydroxyapatite interface in all specimens as well as active remodeling of the hydroxyapatite matrix. The results of this study suggest that porous hydroxyapatite may be a suitable bone substitute in maturing calvarial bone defects, achieving superior osseous integration and volumetric bone gain while undergoing concurrent resorption and remodeling.

Animals↗

PubMed1999

The direct effect of intraorbital pressure on orbital growth in the anophthalmic piglet.

Tissue expanders placed within the orbit can have a positive effect on orbital and ipsilateral midfacial growth. To date, there is no precise method for controlling and monitoring expansion to induce normal growth in the developing facial skeleton. The present study was undertaken to determine the optimal physiologic pressure required to stimulate normal orbital growth and to determine whether above-normal growth could be achieved with higher intraorbital pressures. Using a neonatal swine model, an accurate method of monitoring intraorbital pressure, precisely controlling intraorbital expansion, and achieving normal orbital growth was explored. Sixteen male, 3-week-old Yorkshire piglets were randomly divided into three surgical groups. In each group, the left orbit was the experimental side, and the contralateral right orbit served as an untreated control. Group 1 (n = 6) underwent enucleation only. Group 2 (n = 5) underwent enucleation and orbital expansion at a near-normal physiologic pressure of 20 mmHg. Group 3 (n = 5) underwent enucleation and orbital expansion at a supernormal pressure of 60 mmHg. Spherical tissue expanders (10 cc) with a separate injection port were utilized as the orbital expanders. Pressure was monitored by an electronic manometer that was calibrated daily. Morphology of the orbits was documented by photography, the dimensions of the orbits were quantitated by three-dimensional mechanical digitization, and orbital volumes were calculated. In the unexpanded, anophthalmic control group, a significant reduction in radial growth after evisceration was seen. In group 2, the orbit stimulated with a consistent pressure of 20 mmHg, just above the physiologic normal pressure of 17 mmHg, showed an increase in radial dimension of 8 percent compared with the unoperated side. In the high-pressure group of 60 mmHg, an increase of 16 percent in the radius was observed over the 4-week period. This led to a corresponding increase in orbital volumes with increased pressure. Utilizing a paired t test, these differences in the radial and volumetric growth of the orbit were statistically significant (p < 0.005). The results obtained demonstrated a direct relationship between intraorbital pressure and the growth of the bony orbit in the radial dimension. On the basis of this study, we concluded that orbital expansion maintained at normal physiologic pressure can stimulate normal orbital growth in the neonatal facial skeleton. In addition, application of above-normal pressures for expansion can induce accelerated orbital growth.

Animals↗