Foramen magnum morphometry in children based on computed tomography examination.

BACKGROUND: The foramen magnum is the largest opening at the base of the skull. The dimensions of the foramen magnum are of significant clinical importance because of the vital structures that pass through it. The aim of the study was the morphometric analysis of the foramen magnum in children based on head computed tomography (CT). MATERIALS AND METHODS: The study was carried out on 84 CTs of the head of children aged 0-18 years; seven age groups were distinguished. The sagittal and transverse dimensions were measured to determine the growth rate, changes between groups, and differences in the foramen size by sex. Statistical analysis of changes was performed. RESULTS: The entire group's mean transverse and sagittal dimensions were 29.08 mm (standard deviation [SD] 3.4 mm) and 35.63 (SD 4.23) mm. By sex, the mean transverse dimension in girls was 28.53 (SD 3.25) mm, and in boys, 29.6 (SD 3.49) mm. The mean sagittal dimension was 35.15 (SD 3.76) mm in girls and 36.09 (SD 4.64) mm in boys. Both dimensions were higher for the male sex. A statistically significant increase in the foramen magnum size was demonstrated up to the age of 36 months in the following age groups; above that age, the increase was statistically insignificant. CONCLUSIONS: The dimensions were similar to those described in adults a moderate dependence of the foramen magnum size on age was found.

The incidence of arm, forearm, and hip osteoporotic fractures during early stage of COVID-19 pandemic.

The study analyzes whether the COVID-19 pandemic affects the incidence of arm, forearm, and hip fractures. Additionally, the change in the overall cost of those fractures treatment was estimated. During the COVID-19 pandemic, the incidence of arm, forearm, and hip fractures and the cost of fracture management are decreased. INTRODUCTION: Purposes of the study were to analyze if COVID-19 pandemic influences the incidence of arm, forearm, and hip osteoporotic fractures and to estimate the changes in costs of their management. METHODS: Data on arm, forearm, and hip fracture incidence were collected for inhabitants aged over 50 years in the district of Tarnowskie Góry and the city of Piekary Slaskie, South Poland, in the early stage of COVID-19 pandemic (77 days, from March 16th to May 31st 2020). These results were compared with the number of fractures noted in years 2015-2019 in the same period of the year. The ratio of analyzed fractures per 100,000 inhabitants was calculated. RESULTS: The recorded numbers of fractures of arm, forearm, and hip were 13, 43, and 29, respectively. The respective mean number for fractures reported in corresponding period in 2015-2019 years was 23.6, 52, and 33. The year fracture incidence calculated per 100,000 inhabitants decreased by 45.8%, 18.4%, and 13.4%, respectively. The estimated numbers of avoided fractures extrapolated for the whole country for arm, forearm, and hip were 1722, 1548, and 947, respectively. The total number of avoided fractures was 4217. The expected nationwide cost reduction for the arm, forearm, and hip fracture management was estimated at € 568,260, € 332,820, and € 1,628,840, respectively. The total cost reduction was € 2,529,920 over the period of observation. CONCLUSION: During COVID-19 pandemic, a decrease of arm, forearm, and hip fracture incidence was observed which may result in decrease of total costs for Polish healthcare system.

The hypothalamic-pituitary-testicular axis and the testicular function are modulated after silver nanoparticle exposure.

Silver nanoparticles (AgNPs) are widely used in industrial and medical applications and humans may be exposed through different routes, increasing the risk of toxicity. We investigated the transcript expression of genes involved in the regulation of the hypothalamic-pituitary-testicular (HPT) axis and the parameters associated with sperm functionality after prepubertal exposure. AgNPs modulated the transcript expression of genes involved in the control of the HPT axis and spermatogenesis in the groups treated with lower doses, while the functional parameters related to sperm and puberty were affected in the groups administered higher doses. These results suggest that the HPT axis is disrupted by AgNPs during the prepubertal and pubertal periods, which are highly susceptible windows for the endocrine-disrupting chemical activity.

The blood antioxidant defence capacity during intermittent hypoxic training in elite swimmers.

The main objective of this study was to examine the chronic effect of simulated intermittent normobaric hypoxia on blood antioxidant defence capacity in swimmers. The study included 14 male and 14 female competitive swimmers performing part of land training under simulated intermittent normobaric hypoxia (O2 = 15.5%) or in normoxia. Land interval training took place twice per week, with a total of 8 training units during the study, performed with individualized intensity. The activities of blood antioxidant enzymes did not change significantly during the first and last training unit in the hypoxic and normoxic group. However, when comparing individual variables a significant effect of exercise was observed on GPx an CAT activities, whereas training units significantly differentiated GPx and GR activities. The oxygen conditions and gender had a significant influence on CAT activity. The total antioxidant capacity was not significantly affected. Only in male swimmers from the hypoxic group did the training significantly increase resting levels of MDA. In conclusion, training in normobaric hypoxia was not an adequate stimulus for the excessive response of the antioxidant defence system, despite increased oxidative stress in these conditions.

Impact of the contact metallization on the performance of photoconductive THz antennas.

Both AuGe based alloys and Ti/Au metal layer stacks are widely used as ohmic metal contacts for photoconductive THz antennas made of low temperature grown GaAs. Here, we present the first systematic comparison between these two metallization types. A series of antennas of both kinds is excited by femtosecond laser pulses and by the emission from two diode lasers, i.e. we test the structures as pulsed THz emitters and as photomixers. In both cases, coherent and incoherent detection schemes are employed. We find that the power emitted from the antennas with AuGe metallization is 50% higher than that of antennas with a Ti/Au metal layer. From a comparison with a photomixer model we conclude that the higher output power results from a lower contact resistance of the AuGe contacts leading to an increased current flow. However, Ti/Au contacts have a higher thermal stability which might be advantageous if high system stability is called for.

Downregulation of Jun kinase signaling in the amnioserosa is essential for dorsal closure of the Drosophila embryo.

BACKGROUND: During Drosophila embryogenesis, Jun kinase (JNK) signaling has been shown to play a key role in regulating the morphogenetic process of dorsal closure, which also serves as a model for epithelial sheet fusion during wound repair. During dorsal closure the JNK signaling cascade in the dorsal-most (leading edge) cells of the epidermis activates the AP-1 transcription factor comprised of DJUN and DFOS that, in turn, upregulates the expression of the dpp gene. DPP is a secreted morphogen that signals lateral epidermal cells to elongate along the dorsoventral axis. The leading edge cells contact the peripheral cells of a monolayer extraembryonic epithelium, the amnioserosa, which lies on the dorsal side of the embryo. Focal complexes are present at the dorsal-most membrane of the leading edge cells, where they contact the amnioserosa. RESULTS: We show that the JNK signaling cascade is initially active in both the amnioserosa and the leading edge of the epidermis. JNK signaling is downregulated in the amnioserosa, but not in the leading edge, prior to dorsal closure. The subcellular localization of DFOS and DJUN is responsive to JNK signaling in the amnioserosa: JNK activation results in nuclear localization of DFOS and DJUN; the downregulation of JNK signaling results in the relocalization of DFOS and DJUN to the cytoplasm. The HINDSIGHT (HNT) Zn-finger protein and the PUCKERED (PUC) JNK phosphatase are essential for downregulation of the JNK cascade in the amnioserosa. Persistent JNK activity in the amnioserosa leads to defective focal complexes in the adjacent leading edge cells and to the failure of dorsal closure. CONCLUSIONS: Focal complexes are assembled at the boundary between high and low JNK activity. In the absence of focal complexes, miscommunication between the amnioserosa and the leading edge may lead to a premature "stop" signal that halts dorsalward migration of the leading edge. Spatial and temporal regulation of the JNK signaling cascade may be a general mechanism that controls tissue remodeling during morphogenesis and wound healing.

Single Price/Case Price Purchasing in orthopaedic surgery: experience at the Lahey Clinic.

BACKGROUND: Hospital revenues for orthopaedic operations are not keeping pace with inflation or with rising hospital expenses. In an attempt to reduce the hospital cost of orthopaedic operations by reducing the cost of operating-room supplies, we developed a Single Price/Case Price Purchasing Program for implants used in total hip arthroplasty, total knee arthroplasty, and total shoulder arthroplasty as well as for arthroscopic shavers and burrs, interference screws, and bone-suture anchors. METHODS: The Lahey Clinic asked orthopaedic vendors to supply all instruments, implants, and disposable items related to these selected products for one single price per unit or case. For example, a single price for total hip arthroplasty implants included instruments, acetabular cups, acetabular liners, acetabular screws, femoral stems, femoral heads, and stem centralizers, if required. The hospital implemented the Single Price/ Case Price Purchasing Program with a competitive-bid request for proposal. Surgeons evaluated the responses to the bidding process, and they made final decisions on product selection. RESULTS: The Single Price/Case Price Purchasing Program at the Lahey Clinic was successful in reducing the cost of orthopaedic implants and supplies. In the present article, we could not disclose the specific prices that we agreed to pay our vendors. The specific cost reductions were 32 percent for hip implants with a change of vendor, 23 percent for knee implants without a change of vendor, 25 percent for shoulder implants with a change of vendor, 45 percent for arthroscopic shavers and burrs without a change of vendor, 45 percent for interference screws without a change of vendor, and 23 percent for bone-suture anchors without a change of vendor. CONCLUSIONS: The Single Price/Case Price Purchasing Program at the Lahey Clinic allowed the hospital to reduce its cost of orthopaedic operations by lowering the cost of operating-room supplies. This cost reduction is important in a health-care economy in which hospital revenues per unit of service or care are decreasing.

The hindsight gene is required for epithelial maintenance and differentiation of the tracheal system in Drosophila.

During animal development, morphogenesis of tissues and organs requires dynamic cell shape changes and movements that are accomplished without loss of epithelial integrity. Data from vertebrate and invertebrate systems have implicated several cell surface and cytoskeleton-associated molecules in the establishment and maintenance of epithelial architecture, but there has been little analysis of the genetic regulatory hierarchies that control epithelial morphogenesis in specific tissues. Here we show that the Drosophila Hindsight nuclear zinc-finger protein is required during tracheal morphogenesis for the maintenance of epithelial integrity and assembly of apical extracellular structures known as taenidia. In hindsight (hnt) mutants tracheal placodes form, invaginate, and undergo primary branching as well as early fusion events. Starting at midembryogenesis, however, the tracheal epithelium collapses or expands to give rise to sacs of tissue. While a subset of hnt mutant tracheal cells enters the apoptotic pathway, genetic suppression of apoptosis indicates that this is not the cause of the epithelial defects. Surviving hnt mutant tracheal cells retain cell-cell junctions and a normal subcellular distribution of apical markers such as Crumbs and DE-Cadherin. However, taenidia do not form on the lumenal surface of tracheal cells. While loss of epithelial integrity is a common feature of crumbs, stardust, and hnt mutants, defective assembly of taenidia is unique to hnt mutants. These data suggest that HNT is a tissue-specific factor that regulates maintenance of the tracheal epithelium as well as differentiation of taenidia.

[Comparison of internal fixation methods for the symphysis in multi-directional dynamic gait simulation]. / Vergleich interner Stabilisierungsverfahren für die Symphyse im multidirektionalen dynamischen Gangbedingungssimulator.

For the stabilization of the ruptured pubic symphysis, rigid forms of fixation such as plate osteosynthesis and flexible fixations such as wire loops or PDS banding have been recommended. All methods have only been tested by static unidirectional loading until failure of the system. By this experimental arrangement Ecke and Hofmann found comparable results for flexible and rigid methods of internal stabilization of the pubic symphysis. They preferred flexible methods to maintain mobility of the symphysis and to prevent symphyseal fusion. We tested dynamic compression plate osteosynthesis, reconstruction plate osteosynthesis, wire loops and PDS banding for internal fixation of injured pubic symphysis in a dynamic multidirectional experimental arrangement simulating gait conditions. The specimens were loaded with 85 N in vertical (y-) direction and 34 N in sagittal (z-) direction, which represent 50% of the forces acting at the pubic symphysis during walking and with a frequency of 1.5 Hz over 55,500 loads simulating the conditions over a 6-week mobilization period. Loading with 100% of the acting forces (corresponding to full weight bearing mobilization) led to early failure of the system. Our experimental analysis showed that neither wire loops nor PDS banding is able to stabilize the ruptured pubic symphysis, even immediately after fixation before loading. During the tests instability increased until failure of the system due to cutting of the bone or breaking of the wires or PDS banding. Success of plate osteosynthesis was dependent on the initial stability of the fixation. Overwinding of the screws, as in osteoporotic bone, lead to increasing loosening during repeated loading, whereas primary stable fixation of the screws was almost completely maintained during the test. In consequence, neither wire loops nor PDS banding should be used for stabilization of injured pubic symphysis if early mobilization with partial weight bearing is desired. Plate osteosynthesis (DC or reconstruction plate) tolerates early half weight bearing in patients with "open-book" injury only if safe screw fixation is guaranteed.

Thyroid hormone inhibits aromatase activity in porcine thecal cells cultured alone and in coculture with granulosa cells.

We cultured porcine thecal and granulosa cells alone or in coculture to define whether thyroid hormone affects aromatase activity in porcine ovarian cells. Dispersed cells were cultured with 10(-9) M triiodothyronine (T3) for 24 hours. Testosterone (final concentration 10(-7) M) was added as aromatase substrate for granulosa cells (Gc) cultured alone. Thecal (Th) androgens serve as a substrate for estradiol secretion by Th cells cultured alone and in coculture with Gc. At the end of the preincubation time, the culture media was removed and replaced with fresh media containing 100 ng follicle stimulating hormone (FSH) or 10(-3) M 8-bromo-cyclic adenosine monophosphate (8-Br-cAMP). After overnight incubation, the culture media was analyzed for estradiol production by radioimmunoassay (RIA). T3 inhibited basal, FSH-stimulated, and 8brcAMP-stimulated estradiol production in all culture conditions. T3 inhibited cAMP analogue 8-Br-cAMP and FSH-induced aromatase activity to a similar extent, thus suggesting that the inhibitory effect of T3 is downstream of cAMP formation. In the second part of the experiment a rabbit polyclonal antibody against human placental cytochrome P-450arom was used to confirm the effect of T3 on aromatase protein in Th and Gc. Pretreatment of Th and Gc with T3 markedly decreased immunostaining for aromatase in both types of cells, suggesting a direct effect of T3 on this enzyme.

Opportunities in Medicare for federally qualified health centers.

Competition for Medicaid managed care recipients has cut into the resources traditionally available to safety net providers. At the same time, a lack of primary care providers in many rural areas has increased the demand for federally funded community health centers to serve senior citizens. To meet the needs of the communities they serve and to maintain revenue streams, community health centers are increasingly serving the Medicare population.

Domain organization of calbindin D28k as determined from the association of six synthetic EF-hand fragments.

Calbindin D28k is an intracellular Ca(2+)-binding protein containing six subdomains of EF-hand type. The number and identity of the globular domains within this protein have been elucidated using six synthetic peptide fragments, each corresponding to one EF-hand subdomain. All six peptides were mixed in equimolar amounts in the presence of 10 mM Ca2+ to allow for the reconstitution of domains. The mixture was compared to native calbindin D28k and to the sum of the properties of the individual peptides using circular dichroism (CD), fluorescence, and 1H NMR spectroscopy, as well as gel filtration and ion-exchange chromatography. It was anticipated that if the peptides associate to form native-like domains, the properties would be similar to those of the intact protein, whereas if they did not interact, they would be the same as the properties of the isolated peptides. The results show that the peptides in the mixture interact with one another. For example, the CD and fluorescence spectra for the mixture are very similar to those of the intact calbindin D28k, suggesting that the mixed EF-hand fragments associate to form a native-like structure. To determine the number of domains and the subdomain composition of each domain in calbindin D28k, a variety of peptide combinations containing two to five EF-hand fragments were studied. The spectral and chromatographic properties of all the mixtures containing less than six peptides were closer to the sum of the properties of the relevant individual peptides than to the mixture of the six peptides. The results strongly suggest that all six EF-hands are packed into one globular domain. The association of the peptide fragments is observed to drive the folding of the individual subdomains. For example, one of the fragments, EF2, which is largely unstructured in isolation even in the presence of high concentrations of Ca2+, is considerably more structured in the presence of the other peptides, as judged by CD difference spectroscopy. The CD data also suggest that the packing between the individual subdomains is specific.

UNC-40, a C. elegans homolog of DCC (Deleted in Colorectal Cancer), is required in motile cells responding to UNC-6 netrin cues.

UNC-6 netrin, a laminin-related protein secreted from neuroglia and neurons along the ventral midline, orients migrating cells and pioneering growth cones on the nematode epidermis. UNC-5, a cell surface protein expressed on motile cells and pioneer axons, orients movements away from UNC-6 sources. UNC-40, a homolog of the cell surface proteins DCC (Deleted in Colorectal Cancer) and neogenin, is also expressed on motile cells and pioneer neurons. UNC-40 acts cell autonomously to orient movement toward UNC-6 sources. For cells coexpressing UNC-5, it helps orient movement away from UNC-6 sources. Finally, UNC-40 helps determine the dorsoventral position of cells undergoing purely longitudinal migrations. Together with the recent report that DCC is a netrin receptor in vertebrates, our results suggest that UNC-40 is a component of UNC-6 receptors on motile cells.

[Biomechanics of the pubic symphysis. Which forces lead to mobility of the symphysis in physiological conditions?]. / Zur Biomechanik der Symphyse. Welche Kräfte führen zur Mobilität der Symphyse unter physiologischen Bedingungen?

For estimation of the loads of fixation devices, physiological movements and acting forces at the symphysis pubis are examined. Experimentally, Walheim determined the movements of the pubic symphysis under physiological conditions (one-leg stance, walking): there is no effective mobility in the horizontal direction. During the one-leg stance he observed symphyseal mobility of up to 2.6 mm (Phi 1.2 mm) in the vertical direction and 1.3 mm (Phi 0.6 mm) in the sagittal direction. During walking he found symphyseal mobility of up to 2.2 mm (Phi 0.9 mm) in the vertical direction and 1.3 mm (Phi 0.6 mm) in the sagittal direction. Until now the forces leading to symphyseal mobility have not been estimated either experimentally or mathematically. In our experimental study we examined ten fresh cadaver anterior pelvic rings by means of a multidirectional force-mobility measurement. Maximal physiological movements, as determined by Walheim, were increasingly induced in ten equal steps, and the forces required were measured for every single step. Out of the resulting force-mobility curves for the ten cadaver specimens the mean force required (with standard deviation) was calculated for each of the ten measure points, separately for the vertical (y-) direction and sagittal (z-) direction. The values were graphically transferred, and a regression curve was created. This curve allows the acting force to be estimated for every movement of the pubic symphysis: During the one-leg stance the mean force to induce mean mobility is 169 N in vertical direction and 148 N in sagittal direction; for maximal mobility a force of 398 N in the vertical direction and 148 N in the sagittal direction is necessary. During walking, the force required to induce mean movement of the symphysis pubis is 120 N in the vertical direction and 68 N in the sagittal direction; for maximal mobility 333 N is required in the vertical direction and 136 N in the sagittal direction. For mobilization of patients with a symphyseal rupture (type Tile B 1) with partial weight-bearing, neutralization of the mean acting forces during the one-leg stance (169 N in the vertical direction, 68 N in the sagittal direction) must be achieved by an adequate fixation device. In cases where full weight bearing is desirable, such as in patients with limited compliance, stability can only be reached by neutralization of the maximal acting forces during walking (333 N in the vertical direction, 136 N in the sagittal direction).

The role of helix formation in the folding of a fully alpha-helical coiled coil.

To determine when secondary structure forms as two chains coalesce to form an alpha-helical dimer, the folding rates of variants of the coiled coil region of GCN4 were compared. Residues at non-perturbing positions along the exterior length of the helices were substituted one at a time with alanine and glycine to vary helix propensity and therefore dimer stability. For all variants, the bimolecular folding rate remains largely unchanged; the unfolding rate changes to largely account for the change in stability. Thus, contrary to most folding models, widespread helix is not yet formed at the rate-limiting step in the folding pathway. The high-energy transition state is a collapsed form that contains little if any secondary structure, as suggested for the globular protein cytochrome c (Sosnick et al., Proteins 24: 413-426, 1996).

Ca2+-binding stoichiometry of calbindin D28k as assessed by spectroscopic analyses of synthetic peptide fragments.

Calbindin D28k is an intracellular Ca2+-binding protein noted for its abundance and specific distribution in mammalian brain and sensory neurons. This protein contains six putative Ca2+-binding sites, referred to as EF-hands. Due to the presence of the large number of putative sites, previous studies have been unsuccessful in definitively establishing the stoichiometry of Ca2+ binding. We describe a synthetic approach to identify the number of Ca2+-binding sites in which 6 33-residue peptides, designated EF1-EF6, corresponding to the 6 EF-hand sequences of calbindin D28k, were made. The response of each peptide to Ca2+ addition was assessed by 1H NMR spectroscopy, circular dichroism (CD) spectroscopy, and agarose gel electrophoresis. The Ca2+ binding by CD experiments was performed at two peptide concentrations, 20 and 200 microM, and the NMR studies at peptide concentrations ranging from 20 to 100 microM. The CD and 1H NMR data show that five of the six peptides bind Ca2+ as isolated peptides, namely, EF1, EF3, EF4, EF5, and EF6. The EF6 peptide appears to bind Ca2+ with lower affinity than the other four functional sites. In contrast, EF2 does not appear to bind Ca2+ under any of the spectroscopic conditions tested. The data suggest that at least five of the six putative sites in the native protein bind Ca2+, although their relative affinities cannot be deduced from studies of the isolated peptides.