The adjunct use of descending neurogenic-evoked potentials when transcranial motor-evoked potentials degrade into warning criteria in pediatric spinal deformity surgery: minimizing false-positive events

PURPOSE

This studies objective was to evaluate the utility of descending neurogenic-evoked potentials (DNEPs) in the setting of transcranial motor-evoked potentials (TCeMEPs) degradation into warning criteria during pediatric spinal deformity surgery.

METHODS

An institutional spinal cord monitoring database was queried to identify all primary and revision pediatric spinal deformity cases, < / = 21 years of age performed from 1/2006 to 12/2021, in which TCeMEPs were the primary motor tract assessment modality which degraded into warning criteria, with subsequent initiation of adjunct DNEPs.

RESULTS

Fourteen surgical cases (0.42%; 3351 total cases) in fourteen patients met inclusion criteria. Mean age was 13.2 years (7.5-21.3).

DIAGNOSES

syndromic (n = 7), kyphosis (n = 3), congenital (n = 2), and idiopathic (n = 2). Three-column osteotomies (3CO)were done in eight patients. TCeMEPs degraded into warning criteria during screw placement (n = 7), 3CO performance/closure (n = 4), or deformity correction (n = 3). DNEPs were present in all cases of warning-criteria TCeMEPs and one case had degradation of DNEPs. Intraoperative Stagnara wake-up tests were performed in only 2/14 cases, with one transient new neurologic deficit (NND). In this specific scenario, DNEPs sensitivity was 50%, specificity 100%, positive predictive value 100%, and negative predictive value 92% to detect aNND.

CONCLUSION

DNEPs were useful in assessing spinal cord function in the setting of TCeMEP data degradation in complex pediatric deformity surgeries. DNEPs demonstrated a higher specificity and positive predictive value in this clinical setting than TCeMEPs when assessing long-term neurologic function after surgery. Based on this small cohort, DNEPs appear to be a useful adjunct modality to TCeMEPs, in this challenging clinical scenario.

Ogden Type I to III tibial tubercle fractures in skeletally immature patients: is routine anterior compartment fasciotomy of the leg indicated?

PURPOSE

Determine the frequency of compartment syndrome of the leg after displaced, operatively treated modified Ogden I to III tibial tubercle fractures (TTFxs), evaluate the preoperative assessment and use of advanced imaging, and need for prophylactic fasciotomies.

METHODS

Retrospective analysis of operatively treated, displaced modified Ogden I to III TTFxs, at our level 1 paediatric trauma centre between 2007 and 2019. Modified Ogden Type IV and V fracture patterns were excluded. Fracture patterns were determined by plain radiographs.

RESULTS

There were 49 modified Ogden I to III TTFxs in 48 patients. None had signs nor symptoms of vascular compromise, compartment syndromes or impending compartment syndromes preoperatively. In all, 13 of the 49 fractures underwent anterior compartment fasciotomy at surgery; eight of the 13 had traumatic fascial disruptions, which were extended surgically. All incisions were primarily closed. There were no instances of postoperative compartment syndromes, growth arrest, leg-length discrepancy or recurvatum deformity postoperatively. All patients achieved radiographic union and achieved full range of movement.

CONCLUSION

The potentially devastating complications of compartment syndrome or vascular compromise following TTFx did not occur in this consecutive series of patients over 12 years. The presence of an intact posterior proximal tibial physis and posterior metaphyseal cortex (Modified Ogden TTFx Type I to III) may mitigate the occurrence of vascular injury and compartment syndrome. Plain radiographs appear appropriate as the primary method of imaging TTFxs, with use of advanced imaging as the clinical scenario dictates. Routine, prophylactic fasciotomies do not appear necessary in Ogden I to III TTFxs, but should be performed for signs and symptoms of compartment syndrome.

LEVEL OF EVIDENCE

Level IV.

Monteggia Fracture in an Extremely Preterm Infant with Biochemical Rickets: A Case Report

CASE

A preterm neonate with biochemical rickets is found to have a Monteggia fracture. The infant underwent percutaneous pinning. There was loss of fixation; however, the infant has been followed since discharge from the hospital and has completely healed with full range of motion.

CONCLUSIONS

The medical management of this entity involves enteral feedings and optimization of nutrients. The optimal surgical treatment of this injury in the neonatal period is not yet known, although percutaneous pinning resulted in normal healing and function. These aspects require clinician awareness of this unique fracture type in a premature patient with fragile bone.

Risk of Injury to Neurovascular Structures During Open Cerclage Wiring of the Femur: A Cadaveric Study

The objective of this study was to examine the risk to the sciatic nerve and femoral artery during open passage of cerclage wires and to evaluate the safest techniques. After a standard lateral approach, cerclage passes along the femur were made in cadaveric specimens. Distance to the sciatic nerve and femoral artery was recorded. Careful technique resulted in an increase in distance to the sciatic nerve and femoral artery. There was an increase in the distance to the femoral artery with passes in an anterior to posterior direction. There was decreased distance to structures proximally and distally. There was a trend toward increased safety with smaller passers. Open cerclage wiring of the femur is safest if proper technique is used, care is taken at the proximal and distal ends of the femur, passes are made in an anterior to posterior direction, and the smallest cerclage passer that can be passed is utilized.

Pediatric forearm fractures with in situ intramedullary implants

PURPOSE

The purpose of this investigation is to present our institutional experience with fractures of the pediatric forearm with in situ intramedullary nails.

METHODS

Six patients treated at our institution for forearm fracture with in situ intramedullary implants between 2004 and 2013 were reviewed. Patient demographics, injury and radiographic characteristics, method of treatment, time to union, and complications were collected from the medical record.

RESULTS

485 patients with forearm fractures were treated with intramedullary implants and six patients presented with a fracture with in situ implants (1.2 %). Fractures in all six patients resulted from a second traumatic event after radiographic healing but before implant removal at a mean of 13.0 months from the initial procedure. One patient had an adequately aligned fracture and was treated with casting without reduction. The remaining five patients (83 %) returned to the operating room for treatment. Two patients underwent rod removal and placement of new intramedullary implants, and two patients were treated with rod removal and plating without attempt at closed reduction. One patient underwent closed reduction in the operating room with successful re-bending of the radial implant and replacement of the ulna implant. All patients went on to uncomplicated radiographic union at a mean 3.6 months.

CONCLUSIONS

The incidence of fracture of pediatric forearm with in situ intramedullary implants is low. This rare complication can be treated by several different methods, including revision TENS placement, revision to plate fixation, or in situ bending of rods, with the expectation for successful uncomplicated union.

Platelets and plasma stimulate sheep rotator cuff tendon tenocytes when cultured in an extracellular matrix scaffold

The addition of platelet-rich plasma (PRP) to rotator cuff repair has not translated into improved outcomes after surgery. However, recent work stimulating ligament healing has demonstrated improved outcomes when PRP or whole blood is combined with an extracellular matrix carrier. The objective of this study was to evaluate the effect of three components of blood (plasma, platelets, and macrophages) on the in vitro activity of ovine rotator cuff cells cultured in an extracellular matrix environment. Tenocytes were obtained from six ovine infraspinatus tendons and cultured over 14 days in an extracellular matrix scaffold with the following additives: (1) plasma (PPP), (2) plasma and platelets (PAP), (3) plasma and macrophages (PPPM), (4) plasma, platelets and macrophages (PAPM), (5) phosphate buffered saline (PBS), and (6) PBS with macrophages (PBSM). Assays measuring cellular metabolism (AlamarBlue), proliferation (Quantitative DNA assay), synthesis of collagen and cytokines (SIRCOL, TNF-α and IL-10 ELISA, and MMP assay), and collagen gene expression (qPCR) were performed over the duration of the experiment, as well as histology at the conclusion. Plasma was found to stimulate cell attachment and spreading on the scaffold, as well as cellular proliferation. Platelets also stimulated cell proliferation, cellular metabolism, transition of cells to a myofibroblast phenotype, and contraction of the scaffolds. The addition of macrophages did not have any significant effect on the sheep rotator cuff cells in vitro. In vivo studies are needed to determine whether these changes in cellular function will translate into improved tendon healing.

Aortic adaptation to pregnancy: elevated expression of matrix metalloproteinases-2 and -3 in rat gestation

The maternal aorta undergoes substantial functional and structural adaptation in pregnancy. Both aortic diameter and compliance are increased and studies of animal and human gestation indicate that these changes are initiated in early pregnancy and maintained until delivery. The mechanisms underlying aortic adaptation in normal pregnancy remain largely unknown but matrix metalloproteinase enzymes (MMP) are likely to play a key role. Gene expression of candidate MMP and specific tissue inhibitors of MMP (TIMP) were investigated in non-pregnant, pregnant (days 7, 14, 21) and postpartum (day 7) rat aorta using real-time PCR. Of the gene transcripts studied (MMP-2, -3, -7, -9, -12, -13, MT1MMP, TIMP-1, -2) in rat aorta, only MMP-3 was significantly elevated with a 24-fold increase observed in late gestation compared to virgin control (P = 0.0001). MMP-2 mRNA appeared constitutively expressed and unchanged at time-points studied, but MMP-2 activity as assessed by gelatin zymography suggested further modulation after transcription and/or post-translation in rat aorta with activity increased in early pregnancy (P < 0.01, compared to virgin control). These data suggest that MMP-2 and MMP-3 may contribute to adaptive processes in the maternal rat aorta at different gestations and further support a role for this family of enzymes in physiological vascular remodelling.

Gestational profile of matrix metalloproteinases in rat uterine artery

Mechanisms underlying structural reorganization of the uterine artery in pregnancy remain largely unknown. Matrix metalloproteinases (MMPs) which are involved in degradation of vascular wall matrix are likely to play a key role. In this investigation of rat uterine artery, key MMPs and the specific tissue inhibitors of MMPs (TIMPs) together with three housekeeping genes were studied before, during and after pregnancy, using real time PCR. Data were analysed by partial least squares analysis as well as by conventional univariate methods. Each gene studied [MMP-2, MMP-3, MMP-7, MMP-9, MMP-12, MMP-13, membrane-type 1 (MT1)-MMP, TIMP-1, TIMP-2, GAPDH, cyclophilin and beta-actin] increased in late pregnancy (day 21). MMP-2, MT1MMP, MMP-3 and TIMP-1 transcripts were also elevated at day 7. TIMP-1 and MMP-3 mRNA expression returned to virgin control values in the post-partum, whereas others remained elevated or increased further (MMP-9, MMP-13). Gelatin zymography showed maximum elevation of MMP-2 at day 21. A novel 43-45 kDa gelatinolytic doublet was observed which increased in density with gestation and may represent an active MMP-2 fragment. Together, these data strongly suggest that MMPs and TIMPs are likely to play an important role in remodelling uterine arteries in rat pregnancy and may represent means by which vasodilatation is maintained in later pregnancy. Continued elevated levels of some MMPs post-partum may contribute to vessel regression and return to a non-pregnant physiological state.

Agrobacterium-mediated T-DNA transfer and integration into the chromosome of Streptomyces lividans

Summary Agrobacterium tumefaciens is the prototype of a prokaryotic organism transmitting DNA across natural kingdom barriers into higher cells. In nature, a specific segment (T-DNA) of the resident Ti plasmid is transferred from this bacterium into plant cells and integrated into the plant cell genome. Expression of the integrated oncogenes contained in the T-DNA results in the tumour disease known as crown gall. Besides plants, the range of transformable recipients is broad and includes fungi and mammalian cells. We now show further extension of this host range, whereby the actinomycete Streptomyces lividans is also a recipient of the T-DNA. A. tumefaciens cells containing a binary vector system with a vir helper plasmid, pUCD2614, and a T-DNA donor plasmid, pUCD5801, were co-cultured with S. lividans hyphae. A. tumefaciens-S. lividans aggregate when the vir genes are induced with acetosyringone, resulting in the transfer of the T-DNA, as evidenced by the formation of transconjugants containing T-DNA genetic markers and the appearance of the T-DNA in these transconjugants. Close examination of the interacted cells revealed a presumably coiled thread-like interconnection with an average width of approximately 30 nm between A. tumefaciens and S. lividans. This interconnecting structure is dependent on virB genes and appears only under the same conditions as that required for T-pilus formation. Insertion of the T-DNA via A. tumefaciens into the S. lividans genome provides a useful genetic tool for generating novel mutants.

Managing metabolic model deficiencies for routine radiation protection purposes at a thorium dioxide facility

At a metallurgical facility using thorium dioxide feed materials, a number of conventional direct- and indirect-bioassay methods were potentially suitable monitoring methodologies when industry-standard dose assessment methodologies were based upon ICRP recommendations issued in 1959. When the ICRP recommended a different dose assessment methodology in 1977, the intake limits for thorium dropped significantly, and conventional bioassay methods for routine monitoring were rendered ineffective. While determining the technical basis for its air monitoring program, the facility noted that the radioactive materials used as feed to the process were highly insoluble. Therefore, their solubility in simulated lung fluids was determined. The results of this determination indicated that the facility's materials, if inhaled, dissolve in the lung at a half-time that is significantly longer than that contained in international consensus standards for Y-class compounds. They also indicated that the secondary dose limits, if adjusted to eliminate the dose contribution from translocated radionuclides, should be higher, and that a derived air concentration based upon more recent international recommendations is more appropriate for use in the facility's routine monitoring program.

Production, partial characterization, and potential diagnostic use of salicylate hydroxylase from Pseudomonas putida UUC-1

An unusual strain of Pseudomonas putida UUC-1 capable of growth at high salicylate concentration (10 gl-1) was investigated with the aim of developing an assay and a biosensor system for determining salicylate in body fluids by utilizing the salicylate hydroxylase enzyme. Medium and growth condition optimization were carried out under chemostat conditions. The highest biomass yield was at 4.0 gl-1 salicylate, 25 degrees C, pH 6.5, and 0.2 h-1 dilution rate. Growth occurred at up to 0.45 h-1 dilution rate, producing 236 Ul-1 enzyme activity and an output of 424 U h-1. The activity and productivity were higher than any reported in the literature for this enzyme. It had a Km value of 2.07 +/- 0.32 microM and an M(r) of approximately 43,000. In addition, its specific activity in the crude extract (0.8-0.9 U mg-1 protein) was similar to the commercially available enzyme. No plasmid DNA was detected in this strain, and no salicylate-negative isolates were obtained when curing with mitomycin C. It is therefore proposed that our strain has a chromosomally located inducible salicylate hydroxylase gene that enables it to grow at high salicylate. This strain also offers a means of cheaply producing large quantities of the enzyme through standard fermentation techniques.

Dihydrofolate reductase synthesis in continuous culture using a methotrexate-resistant Escherichia coli

A methotrexate-resistant strain of Escherichia coli Type I produced exceptionally high levels of the enzyme dihydrofolate reductase (EC 1.5.1.3) in 6 h of batch fermentation. The culture had markedly improved performance under chemostat culture conditions in terms of enzyme yield and output. Temperature, pH, dilution rates, and nutrient composition were optimized under chemostat culture conditions. A maximum enzyme yield of 10,360 U l-1 and a specific activity of 22.84 U mg-1 were obtained under chemostat conditions at pH 7.0, temperature 37 degrees C, and dilution rate 0.2 h-1, using media containing 1.0 and 0.6% (w/v) dextrose and yeast extract, respectively. The culture's performance and enzyme yields in chemostat and the feasibility of large-scale production are discussed.

The inflammatory cervical smear: a study in general practice

This study set out to determine whether the term 'inflammatory' in a cervical smear report implies underlying infection or whether it could be masking cancerous or precancerous changes. Of 826 smears taken in one practice over one year, 42 demonstrated some degree of inflammatory change. Thirty four of these women presented for swabs and almost half (47%) had a microbiologically proven infection. This group was further subdivided, and of those whose smears were reported as simple 'inflammation', just over one third (35%) were infected but of those whose smears were reported as 'severe inflammation', over two thirds were infected (73%). The commonest organisms isolated were Gardnerella vaginalis and Candida albicans. It would therefore appear to be worthwhile to treat patients who report severe inflammation with metronidazole and with anti-fungal pessaries before the smear is repeated. Following treatment two women went on to show dyskaryosis within five months. On colposcopy one of these women was found to have invasive cervical squamous cell carcinoma. It is concluded that whether women with inflammatory smears are treated or not, it is mandatory to repeat the smear, ideally within five months.

The relationship between lysosomal enzyme release and protein phosphorylation in human monocytes stimulated by phorbol esters and opsonized zymosan

Since it was established that phorbol esters bind to and activate protein kinase C, a proposed mechanism of action for these compounds has been the phosphorylation of specific protein substrates (Niedel, J. E., Kuhn, L. J., and Vandenbark, G. R. (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 36-40; Castagna, M., Takai, Y., Kaibuchi, K., Sano, K., Kikkawa, U., and Nishizuka, Y. (1982) J. Biol. Chem. 257, 7847-7851). To better understand this proposed relationship, we investigated the ability of a series of phorbol esters to elicit lysosomal enzyme release (LER) and specific substrate phosphorylation in human monocytes. In this system, phorbol 12-myristate 13-acetate stimulated the secretion of the lysosomal enzyme N-acetyl-beta-D-glucosaminidase in both a time- and concentration-dependent manner. Furthermore, the ability of a series of phorbol esters to stimulate LER was characterized and found to be in good agreement with the relative order of these compounds to stimulate the phosphorylation of four endogenous protein substrates. Phorbol ester-stimulated protein phosphorylation was examined in intact cell preparations and found to be concentration and structure-dependent. The phosphoproteins (pp) were designated pp28, pp55, pp61, and pp66 corresponding to their molecular masses in kilodaltons. These findings are consistent with the hypothesis that phorbol ester-mediated effects are the result of protein kinase C activation and subsequent protein phosphorylation. Finally, opsonized zymosan was found to elicit a concentration-dependent stimulation of N-acetyl-beta-D-glucosaminidase release similar in magnitude and time course to phorbol ester-stimulated LER. Opsonized zymosan also stimulated the phosphorylation of two phosphoproteins (pp61 and pp66) in a concentration-dependent manner. Specific phosphorylation of pp61 and pp66 by both secretagogues, phorbol 12-myristate 13-acetate and opsonized zymosan, suggests these two proteins may be key to the functional response of LER in human monocytes.

The imaging revolution and radiation oncology: use of CT, ultrasound, and NMR for localization, treatment planning and treatment delivery

The explosion of new imaging technologies such as X ray computed tomography (CT), ultrasound (US), positron emission tomography (PET), and nuclear magnetic resonance imaging (NMR) has forced a major change in radiation therapy treatment planning philosophy and procedures. Modern computer technology has been wedded to these new imaging modalities, making possible sophisticated radiation therapy treatment planning using both the detailed anatomical and density information that is made available by CT and the other imaging modalities. This has forced a revolution in the way treatments are planned, with the result that actual beam configurations are typically both more complex and more carefully tailored to the desired target volume. This increase in precision and accuracy will presumably improve the results of radiation therapy.

Dose to lung in primary breast irradiation

Using anatomic data derived from computerized tomography (CT) scans of the torso, the volume of lung irradiated during primary breast treatment has been measured for a variety of irradiation techniques. Two-field tangential plans which are angled into lung to treat also the internal mammary nodes have been compared to three-field plans which include a separate internal mammary field (IMF). The volume of lung achieving high dose (greater than 3000 rad) is similar in both techniques when photons only are used. Electron beam treatment of the IMF is successful in lowering the lung dose. Additional treatment plans that angle the IMF parallel to the tangential fields may offer some theoretical advantage.

Insect moulting hormones. LIV. The synthesis and biological acitvity of some alkylated ecdysone analogues

A number of ecdysone analogues were prepared, with alkyl substituent groups projecting above and below the plane of the A-ring of the analogue (37), to gain an insight into the steric requirements for the binding of ecdysteroids to the hormone receptor. Moulting hormone activities of these analogues, determined with the Calliphora bioassay, revealed that the β-face is more sensitive to projecting alkyl groups than the α-face. It is concluded that binding of the hormone to the receptor probably takes place on both sides of the A-ring but that a close fit is more important on the β-face than the α-face.