Biomedical subjects
Publications and source records attributed to K C Chung.
Cephalhematoma is a collection of blood under the periosteum of the skull and is frequently associated with traumatic delivery. The distinct calcified form of this disease is rare and has not been reported in the plastic surgery literature. In this report, we present an infant with a large calcified cephalhematoma associated with a skull defect and discuss its management.
CcpA was purified from Escherichia coli BL21 (lambda DE3)/pLysS carrying plasmid pTSC5, which was constructed by inserting the ccpA gene into the polycloning site of pGEM4. The purified protein migrated in sodium dodecyl sulfate-polyacrylamide gel electrophoresis with an apparent mass of 38 kDa but was eluted from a calibrated Bio-Gel P-100 column with an apparent mass of 75 kDa. Western blot (immunoblot) analysis revealed the presence of CcpA in E. coli BL21 (lambda DE3)/pLysS/pTSC5, which carries ccpA, and in wild-type Bacillus subtilis 168 but not in E. coli BL21 (lambda DE3)/pLysS/pGEM4 or in B. subtilis WLN-29, in which ccpA is inactivated by transposon Tn917 insertion. Purified CcpA bound to DNA containing amyO and retarded its mobility in electrophoretic mobility shift analysis. Complete retardation of the DNA required 75 ng of CcpA per assay. In DNase protection analysis, CcpA bound to DNA containing amyO and protected a region spanning amyO when either DNA strand was labeled. Mutant forms of amyO not effective in catabolite repression were not retarded by CcpA.
The cyclic AMP (cAMP)-inducible promoter from the rat lactate dehydrogenase A subunit gene (LDH A) is associated with a distal negative regulatory element (LDH-NRE) that represses inherent basal and cAMP-inducible promoter activity. The element is of dyad symmetry, consisting of a palindromic sequence with two half-sites, 5'-TCTTG-3'. It represses the expression of an LDH A/chloramphenicol acetyltransferase (CAT) reporter gene in a dose-dependent, orientation- and position-independent fashion, suggesting that it is a true silencer element. Uniquely, it selectively represses cAMP-responsive element (CRE)-dependent transcription but has no effect on promoters lacking a CRE sequence. The repressing action of LDH-NRE could be overcome by cotransfection with LDH A/CAT vector oligonucleotides containing either the LDH-NRE or CRE sequence. This suggests that the reversal of repression was caused by the removal of functional active, limiting transacting factors which associate with LDH-NRE as well as with CRE. Gel mobility shift, footprinting, and Southwestern blotting assays demonstrated the presence of a 69-kDa protein with specific binding activity for LDH-NRE. Additionally, gel supershift assays with anti-CREB and anti-Fos antibodies indicate the presence of CREB and Fos or antigenically closely related proteins with the LDH-NRE/protein complex. We suggest that the LDH-NRE and CRE modules functionally interact to achieve negative modulation of cAMP-responsive LDH A transcriptional activity.
Osteoporosis is a major complication of long-term steroid use. In this experimental study, the effect of lipid clearing agents on the preservation of bone mass was assessed. New Zealand white rabbits were divided into four groups: normal control, steroid only, steroid plus lovastatin and steroid plus bezafibrate. Treatments were continued for either 6 to 8 weeks or 13 to 15 weeks, after which the rabbits were sacrificed. Each rabbit's trabecular bone area from the central saggital sections of the femoral head was measured. At 6 to 8 weeks there was no significant difference between the steroid groups, but at 13 to 15 weeks the bone area in the steroid only group was significantly lower than in the groups that had also received lipid clearing agents. Histologic examination of livers from the normal control group showed significantly less degeneration than in all of the steroid groups. Lipid clearing agents appear to maintain bone mass in the femoral head, but do not avert fatty changes in the liver in steroid treated rabbits. Concomitant use of lipid clearing agents with steroids may have the potential to decrease the severity of steroid induced osteoporosis.
The rat lactate dehydrogenase (LDH) A subunit gene promoter contains a putative AP-1 binding site at -295/-289 bp, two consensus Sp1 binding sites at -141/-136 bp and -103/-98 bp, and a single copy of a consensus cyclic AMP-responsive element (CRE) at -48 to -41 bp upstream of the transcription initiation site. Additionally, an as yet unidentified silencer element is located within the -1173/-830 bp 5'-flanking region. Transient transfection analyses of a -1173/+25 bp LDH A-chLoramphenicol acetyltransferase fusion gene has indicated a complete inability of the promoter fragment to direct basal or forskolin-induced transcription. Deletion of the -1173/-830 bp sequence restored basal and cyclic AMP (cAMP)-inducible activity. Point mutations in the Sp1 binding sites of a -830/+25 bp promoter fragment reduced basal but not the relative degree of cAMP-inducible activity. cAMP-regulated transcriptional activity was dependent upon an 8 bp CRE, -TGACGTCA-, located at the -48/-41 bp upstream region. Mutations in the CRE abolished cAMP-mediated induction and reduced basal activity by about 65%. The CRE binds a 47 kDa protein which has previously been identified as CRE binding protein (CREB)-327, an isoform of the activating transcription factor/CREB transcription factor gene family. Co-transfection of a vector that expresses the catalytic subunit of cAMP-dependent protein kinase stimulates LDH A subunit promoter activity suggesting that cAMP induces LDH A subunit gene expression through phosphorylative modification of CREB-327. This study emphasizes a fundamental role of several modules including Sp1 and CREB binding sites in regulating basal and cAMP-mediated transcriptional activity of the LDH A gene.
The development, implementation and evaluation of an algorithm designed to find optimal seat support surfaces is presented. The algorithm has been developed and implemented on an active contour measurement device. The device consists of an array of positioning elements equipped with force sensors for feedback. With a patient seated on the array, the algorithm is designed to find a seat contour that optimally satisfies given performance criteria. The performance criteria are based on measured stiffness of the soft tissues. A theoretical development of the algorithm is presented along with the modifications made to the algorithm during implementation. The results from several tests using man-made test bodies and a prototype contour gage are presented to verify the algorithm's performance.
Three types of grafts were investigated in rabbits to measure fixation strength of bony ingrowth into porous-coated titanium alloy implants. Autogeneic iliac crest bone (ABG), allogeneic demineralized bone matrix (DBM), and DBM augmented with fibrin glue (DBM + FG) grafts were compared with a press-fit implant control group. Initially, the ABG group required eight weeks and the DBM and DBM + FG groups 12 weeks to achieve fixation strength similar to that of the press-fit group at four weeks. Strength increased with time and at 16 weeks reached 83 kg in the ABG group, 71 kg in the DBM group, and 79 kg in the DBM + FG group, compared with 86 kg for the press-fit group. The ratio of the DBM and the DBM + FG group push-out forces to the ABG push-out force improved from 40% at four weeks to more than 80% at 16 weeks. Histologic analysis of bone ingrowth showed that at 12 weeks, bony ingrowth accounted for 21%, 22%, 16%, and 32% of the porous area in the ABG, DBM, DBM + FG, and press-fit groups, respectively. After eight weeks, there was no statistical difference between DBM, DBM + FG, and ABG grafts in either strength or bony ingrowth. The results demonstrate that over long periods, DBM grafts provide fixation stability comparable with that of autogeneic bone graft.
Three types of material that have shown potential as coatings for orthopaedic implants were studied. Using a weight-bearing canine model, Ti-6A1-4V femoral intramedullary rods coated with (1) sintered titanium beads, (2) plasma-sprayed hydroxyapatite, and (3) silyl coupled polysulfone beads were evaluated for mechanical strength and bone ingrowth. The model was designed to secure optimal prosthetic stability by obtaining maximal bony ingrowth during an initial non-weight-bearing phase, then stressing the implant during a full-weight-bearing phase. None of the rods coated with titanium beads failed. All 17 polysulfone-coated rods failed, 13 of them at the interface between the polysulfone coating and the titanium core. Of 18 rods coated with hydroxyapatite, 15 suffered implant breakdown at the interface between the hydroxyapatite coating and the titanium core. This may be due to dissolution of the plasma-sprayed hydroxyapatite in vivo. Testing of retrieved specimens from both hydroxyapatite- and polysulfone-coated implants showed that the shear strength at the coating-rod interface had decreased to less than 40% of the shear strength at manufacture. Despite mechanical failure, histologic study showed extensive bone ingrowth or apposition onto both the polysulfone and hydroxyapatite coatings.
The design, application and evaluation of a specialized, personal computer-based manufacturing system for contouring foam cushions is presented. The topics discussed include both the hardware configuration and the software design. The target applications of this device are local or centralized fabrication of custom-contoured seat cushions. Although the technologies used for the development and implementation of this system are not new, using a personal-computer-based (PC) controller in place of a stand-alone numerically controlled (NC) motion controller significantly reduced the cost associated with this component. Further reductions in cost resulted from an optimization of the mechanical configuration for the dedicated task of carving foam cushions.
This article describes the development of a computer-controlled system for measuring anatomical contours and forces at the interface with seat surfaces. The system was designed to eliminate the cause of pressure sores, which are a major problem for wheelchair-bound individuals. A parallel and compatible system also has been developed for the rapid, precise, and cost-effective fabrication of custom-contoured seat cushions and other body supports from a range of open- and closed-cell foam materials.
This project focused on identifying the influence of subject characteristics and foam properties on seat contours in order to explain the load transfer between the buttocks and cushion. Seat contours were recorded for 17 people (11 spinal cord injured and six able-bodied individuals). Contour characteristics were represented by maximum contour depth, surface area, and displaced volume. Subject characteristics were represented as intertrochanteric distance, body weight, and lower extremity muscle tone. Two foams with different degrees of stiffness (45- and 55-pound indentation load deflection [ILD]) were studied. Multiple regression equations were calculated for each of the three contour characteristics by entering in all three subject attributes. While the equations differ, all six exhibited a significant Multiple R (range: 0.79 to 0.92). Each subject characteristic was a significant predictor of at least one contour trait (p less than 0.05). The major difference between the two cushions was the predictive ability of muscle tone. For the stiffer HR55 foam, muscle tone was the strongest predictor of all contour characteristics. Therefore, some conclusions can be drawn concerning the relationship between foam stiffness, tone, and resulting seat contours. These relationships help define the differences in load transfer as subject and cushion characteristics vary and are important in the design of contoured foam for use as wheelchair cushions.
Previous research indicated that matching a cushion to the shape of the buttocks results in less tissue distortion and lower interface pressures. A system was developed to measure body contours and fabricate a cushion to match the measured contour. This project fabricated contoured foam cushions for 11 persons with spinal cord lesions (C5-L3). Mean pressures were compared on two flat and two contoured foams with different degrees of stiffness. Deflection characteristics on flat foam were compared to deflection on contoured foam in order to analyze loading differences. Material studies were determined by examining the load-deflection curves for flat foams of 1-, 2-, and 3-inch thicknesses. It was found that sitting on contoured foam resulted in a lower pressure distribution than sitting on flat foam (p less than 0.05), and sitting on a soft foam (ILD = 45) resulted in a lower pressure distribution than sitting on a stiffer foam (ILD = 55) (p less than 0.05). Results of the deflection measurements and compression tests were used to explain the loading differences at the seat interface of flat and contoured cushions. Loaded contoured foam demonstrated increased enveloping of the buttocks, decreased foam compression, and a more uniform pressure distribution. These attributes are typical of a safer sitting surface and may indicate less tissue distortion.
The purpose of this study was to determine the usefulness of custom-contoured cushions (CCCs) in providing a safe sitting surface. The efficacy of CCCs was investigated using ten spinal cord injured persons who evaluated contoured foam as their primary wheelchair cushion. External pressures at the seat interface were measured on a subject's regular cushion and on a CCC to compare the respective load distributions. Pressure distributions measured on a CCC were statistically lower than those measured on the subject's usual cushion (p less than .05). Eight clinical variables were used to judge each cushion's effect on the functional abilities of wheelchair users. Sitting on a CCC seemed to improve posture and balance when compared to the subject's regular cushion. Based on these results, it is suggested that contouring technology be developed as a clinical tool for managing wheelchair users' seating problems.
Central nervous system is often involved by herpes zoster but it is very rarely seen that contralateral hemiparesis or hemiplegia developed after herpes zoster ophthalmicus. We report a case of herpes zoster ophthalmicus followed by the delayed contralateral hemiparesis. A 33-year-old man developed acute cerebral infarction and resultant right hemiparesis 44 days after herpes zoster ophthalmicus in the left side. Brain CT disclosed hypodense area in the left basal ganglia. Cerebral angiography revealed segmental narrowing of M1 portion of the right middle cerebral artery.
The hypothesis that white women with endometrial cancer survive longer than black women with this disease was evaluated in a retrospective analysis of a population-based, prospective cohort study. All female residents of metropolitan Atlanta with a first diagnosis of primary endometrial cancer from 1978 through 1982 were eligible for inclusion. The 628 white and 105 black women were followed up through June 1984 to determine survivorship. Race was evaluated as a prognostic factor with univariate, multivariate, and excess death rate analyses. Overall, an estimated 89.2% of whites and 61.6% of blacks survived 3 years from the time of diagnosis. Although black women tended to have more advanced disease at the time of diagnosis and a higher proportion of undifferentiated malignancies, the racial difference in survival persisted after adjustment for these factors. When initial therapy was considered, race remained a significant prognostic determinant among women who did not receive radiation therapy.
Past studies of the incidence of acute myocardial infarction (AMI) have found information for patients managed at home difficult and expensive to obtain. This study attempted to find whether the efficiency of gathering this information could be improved, or if this group of patients could be neglected entirely. A random sample of 270 doctors in Perth were asked about their management of cases of suspected AMI at home. Of these doctors, 78% said that they never managed AMI at home; excluding such doctors before seeking voluntary notification of new cases managed at home could make population surveys of AMI more efficient. For patients under 65 it was estimated that about 1% or less of non-fatal cases meeting World Health Organization criteria for definite AMI were managed at home. Thus neglecting this group would probably cause little bias in computing incidence rates for AMI in Perth.
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