The unreamed humeral nail--a biological osteosynthesis of the upper arm

The relation of the physiological releases of growth hormone-releasing hormone (GHRH) and growth hormone (GH) into the circulation in various conditions was investigated using a sensitive and specific radioimmunoassay for plasma GHRH. The mean fasting plasma level of immunoreactive (IR)-GHRH in 72 normal adults was 10.3 +/- 0.5 (mean +/- SEM) pg/ml and there was no significant sex difference in the level. The concentrations of IR-GHRH in plasma from the umbilical artery and umbilical vein were 107.3 +/- 20.5 pg/ml and 33.6 +/- 3.8 pg/ml, respectively, and a marked arterio-venous gradient was observed in all 12 individuals examined. The plasma level of IR-GHRH in the maternal vein was significantly lower than that in the cord blood, but was similar to that in non-pregnant women. In normal adults, although there was no apparent fluctuation in the level of plasma IR-GHRH or of plasma GH during bed rest, a significant increase of plasma IR-GHRH was detected followed by, or synchronized with the surge of plasma GH after oral administration of L-dopa. In contrast, on L-arginine infusion, no proportional elevation of plasma IR-GHRH with increase in plasma GH was observed. During and after intravenous infusion of somatostatin, the circulating IR-GHRH level did not increase, but on stopping the infusion there was an immediate and marked rebound surge of GH. We conclude that 1) the elevated IR-GHRH in the cord blood plasma originates from the fetus and may have a primary role in enhancing secretion of GH which promotes growth in early human life, and 2) the participations of GHRH in the mechanisms of GH secretion seen after administrations of L-dopa, L-arginine and somatostatin are different.     

Retrograde nailing of humerus shaft fractures with the unreamed humerus nail. An international multicenter study

Combined with the new unreamed humeral nail (UHN) (Synthes), the retrograde approach to the endomedullary canal of the humeral shaft promises careful reduction and fixation of humeral shaft fractures. This prospective multicenter study reports and analyses 102 retrograde nailings with the UHN and their operative procedures. Seven patients with pathological fractures have died meanwhile, but 75 patients could be followed up until bone healing. Seventy-three fresh humeral shaft fractures, 12 pseudarthrosis, 3 refractures and 14 pathological fractures have been treated with the UHN. In 98 cases (96.1%) the surgeon estimated fracture stability well enough to initiate immediate postoperative elbow and shoulder mobilization. The difficulties involved with free-hand interlocking proximally at the nail tip in 5.9%, fissure or avulsion at the insertion point in 3.9% and radial nerve palsy also in 3.9% of the cases were the most important intraoperative complications. In all 75 patients followed up, bone healing occurred, but five fractures (6.7%) needed more than 8 months connected with a second operative procedure. In one case spongious bone transplantation and new locking bolts had been performed. In three cases a special compression device has been used, whereas in one case also a new nail and in the second spongious bone transplantation had been added. In the fifth case plate osteosynthesis had been performed. At the end of treatment 89.4% of the patients had excellent shoulder function and 88.0% excellent elbow function. Once the indication for surgery is established, the UHN can be considered a reliable and safe implant for stabilizing humeral shaft fractures.     

How much is a quantum controller controlled by the controlled system?

We consider unitary transformations on a bipartite system A × B. To what extent entails the ability to transmit information from A to B the ability to transfer information in the converse direction? We prove a dimension-dependent lower bound on the classical channel capacity C(A ← B) in terms of the capacity C(A → B) for the case that the bipartite unitary operation consists of controlled local unitaries on B conditioned on basis states on A. If the local operations are given by the regular representation of a finite group G we have C(A → B) = log |G| and C(A ← B) = log N where N is the sum over the degrees of all inequivalent representations. Hence the information deficit C(A → B) ? C(A ← B) between the forward and the backward capacity depends on the “non-abelianness” of the control group. For regular representations, the ratio between backward and forward capacities cannot be smaller than 1/2. The symmetric group S _n reaches this bound asymptotically. However, for the general case (without group structure) all bounds must depend on the dimensions since it is known that the ratio can tend to zero. Our results can be interpreted as statements on the strength of the inevitable backaction of a quantum system on its controller.     

Quasi-order of clocks and their synchronism and quantum bounds for copying timing information

The statistical state of any (classical or quantum) system with nontrivial time evolution can be interpreted as the pointer of a clock. The quality of such a clock is given by the statistical distinguishability of its states at different times. If a clock is used as a resource for producing another one the latter can at most have the quality of the resource. We show that this principle, formalized by a quasi-order, implies constraints on many physical processes. Similarly, the degree to which two (quantum or classical) clocks are synchronized can be formalized by a quasi-order of synchronism. Copying timing information is restricted by quantum no-cloning and no-broadcasting theorems since classical clocks can only exist in the limit of infinite energy. We show this quantitatively by comparing the Fisher timing information of two output systems to the input's timing information. For classical signal processing in the quantum regime our results imply that a signal looses its localization in time if it is amplified and distributed to many devices.     

Treating the Independent Set Problem by 2D Ising Interactions with Adiabatic Quantum Computing

We construct a nearest-neighbor interaction whose ground states encode the solutions to the NP-complete problem independent set for cubic planar graphs. The important difference to previously used Hamiltonians in adiabatic quantum computing is that our Hamiltonian is spatially local. Due to its special structure our Hamiltonian can be easily simulated by Ising interactions between adjacent particles on a 2D rectangular lattice. We describe the required pulse sequences. Our methods could help to implement adiabatic quantum computing by physically reasonable Hamiltonians like short-range interactions. Therefore, this universal resource Hamiltonian can be used for different graphs by applying suitable control operations. This is in contrast to a previous proposal where the Hamiltonians have to be wired in hardware for each graph. PACS: 03.67.Lx     

Treatment of distal femoral fractures in the elderly. Results with the retrograde intramedullary supracondylar nail

The incidence of neural tube defects including myelomeningocele, which is one of the most common causes of infant and childhood disability, can be substantially reduced by folic acid supplementation to the diet of women before and during the early stages of pregnancy. All females of childbearing age should be taking folic acid supplements of 0.4 mg/day (400 micrograms/day) and consuming a diet rich in folate. Because many pregnancies are unplanned, supplementation should not await plans for pregnancy. Because pediatric nurse practitioners are in frequent contact with both adolescent patients and patients whose mothers are of childbearing age, and because pediatric nurse practitioners have an interest in preventing neural tube defects in future pediatric patients, they are in a good position to provide the necessary anticipatory guidance regarding the critical need for adequate folic acid intake by females of childbearing age. This article discusses and includes guidelines for providing this anticipatory guidance.     

The retrograde intramedullary supracondylar nail: an alternative in the treatment of distal femoral fractures in the elderly?

To find out whether retrograde nailing of distal femoral fractures is beneficial for the aged patient, we performed a prospective study of consecutive patients 65 years or older with distal femoral fracture treated with a retrograde femoral nail between 1 March 1993 and 30 April 1996 in our department. In total, 26 patients with unilateral distal femoral fractures had been treated in our department, and 24 patients had been followed up for more than 12 months. All fractures had healed. Six patients did not walk before the injury. According to the Neerscore we counted 10/18 excellent results (> or = 85 points), 6/18 good results (> or = 70 points), 2/18 fair results (> or = 55 points) and no failures (< 55 points). Retrograde intramedullary nailing makes a biological osteosynthesis of distal femoral fractures possible. Even in our aged patients good functional results could be obtained. Poor hold of the distal interlocking screws and difficult proximal locking are the two major technical problems encountered with this implant. Early weight-bearing is not advisable.