Fast reconfigurable optical image switching/routing system

A novel system that is capable of switching/routing two-dimensional images in arbitrary configurations is described. The switching network can be reconfigured in a few microseconds with high light efficiency.

Biomechanical evaluation of anterior thoracolumbar spinal instrumentation

STUDY DESIGN

A biomechanical study was designed to assess relative construct stabilities of modern anterior thoracolumbar instrumentations in a calf spine model with an anterior and middle column defect.

OBJECTIVES

The purpose is to compare the biomechanical stability of various anterior fixation devices in an unstable calf spine model.

SUMMARY OF BACKGROUND DATA

Modern types of anterior thoracolumbar instrumentations evolved to either rods or plates. Biomechanical properties and comparative studies of these instrumentations are lacking.

METHODS

Twenty fresh calf spines (L2-L5) were used for the biomechanical tests. L2 and L5 vertebrae were used to attach the loading and base frames, respectively. Specimens underwent nondestructive biomechanical tests performed using a three-dimensional motion measuring system. In each specimen, three different cases were tested: intact spine, anterior fixation with an interbody graft after total discectomy and endplate excision of L3-L4 disc, anterior fixation only without the graft. Four anterior fixators, University Anterior Plating System, the Kaneda device, the Z-plate, and Texas Scottish Rite Hospital system were used. Each device was tested on five specimens. A polymethylmethacrylate block was inserted into the disc space to simulate the interbody grafting, and a fixation device was implanted with axial compression. Rotational angles of the L3-L4 segment stabilized by a fixation device and graft were normalized by the corresponding angles of the intact specimen to study the overall stabilizing effects.

RESULTS

With the interbody graft and fixation devices, all showed significant stabilizing effects in flexion, extension, and lateral bending. All devices restored axial rotation stability to intact specimen, but only the Kaneda device restored the torsional stability beyond the intact specimen. No statistical differences in stabilizing effects in axial rotation were found between any of the tested devices. When the graft was removed, the Kaneda device significantly decreased the motions in all directions compared with the intact motion, whereas the University plate decreased the motions in flexion, extension, and lateral bending. The Texas Scottish Rite Hospital system was found to reduce the flexion and lateral bending motions significantly, and Z-plate decreased lateral bending motions only. Stabilizing effects of the interbody graft were significant in lateral bendings for all devices. Additionally, the significant stabilizing role of the graft was noted in flexion and extension in Z-plate only. The graft did not significantly reduce the axial rotation motion in any instrumentations.

CONCLUSIONS

Modern anterior instrumentations for the thoracolumbar spine, such as the Kaneda device, Texas Scottish Rite Hospital system, Z-plate, and University plate, restored the stability in all motions when an interbody graft was inserted. The stability of fixation devices revealed that the Kaneda device is the best, particularly in restoring the torsional stability. The information on the relative stability provided by different instrumentations should help the spine surgeon in choosing the appropriate instrumentation for the particular circumstance.

Modification of tumor microenvironment by cytokine gene transfer

The tumor microenvironment is determined by the interactions between host and tumor cells, a process in which cytokines play a major role. We have used retroviral vectors to insert and express cytokine genes in tumor cells so as to induce predictable changes in the host cells that infiltrate tumors. This frequently caused changes in tumor cell phenotype through autocrine/intracrine pathways. We reasoned that cytokine-induced alterations in tumor cell phenotype and/or in infiltrating host cells might alter the in vitro and in vivo cellular response to irradiation. In the present paper we document some of the effects of expression of interleukin-6 (IL-6) and IL-7 genes in tumor cells in this regard. The studies support the hypothesis that cytokines may play a role in determining both intrinsic tumor radioresponsiveness and the tumor microenvironment and in these ways may influence in vivo tumor irradiation responses. Possible cytokine gene-mediated approaches to radiotherapy cancer are discussed.

Influence of the timing of FK 506 (Tacrolimus) administration on recovery of renal function from warm ischemic injury in rats

The influence of timing of FK 506 (Tacrolimus) administration on renal function and recovery from renal warm ischemia was studied in Sprague-Dawley rats. Animals were administered FK 506 and subjected to 60 min of renal warm ischemia by temporary occlusion of the renal artery and vein. No significant differences in serum creatinine levels among rats subjected to renal ischemia, FK 506, or FK 506 vehicle (methanol and 5% dextrose in water) were demonstrated. In contrast, FK 506 administration (4 mg/kg intraperitoneally) in combination with renal warm ischemia resulted in significant deterioration of renal function with peaking of serum creatinine on day 2. The timing of FK 506 administration relative to renal ischemia did not significantly affect serum creatinine levels. Rats that received FK 506 either 24 hr pre-ischemia, 4 hr pre-ischemia, 4 hr post-ischemia, or 24 hr post-ischemia all showed similar serum creatinine levels on day 2 (3.85 +/- 0.9, 4.7 +/- 0.5, 3.8 +/- 0.9, and 5.1 +/- 0.6 mg/dl, respectively, p = NS). In all animals, serum creatinine returned to baseline values by day 10. Histopathologic examination of kidneys revealed tubular atrophy and dilatation with tubular calcifications at the corticomedullary junction in FK 506 treated animals with or without ischemia. Our data suggest the timing of FK 506 administration in rats subjected to renal warm ischemia does not influence the extent of renal injury with an equally deleterious effect seen when administered within a 24 hr period of an ischemic event. Changes in kidney morphology, however, were seen in all FK 506 treated rats, with or without a period of warm ischemia.

G2/M-phase arrest and release in ataxia telangiectasia and normal cells after exposure to ionizing radiation

Cells from patients with ataxia telangiectasia (AT) are abnormal in their response to irradiation as judged by clonogenic survival and accumulation in G2 phase. The relationship of the results of these two assays, however, is still a matter of controversy. Flow cytometry was used to measure the distribution of cells in the phases of the cell cycle after 2 Gy irradiation in Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCLs) and SV40-transformed fibroblasts. AT cells showed increased and prolonged accumulation in G2/M phase regardless of the cell type (lymphoblastoid or fibroblast) or complementation group (A, C or D). To test the hypothesis that prolonged accumulation of AT cells in G2 phase after irradiation was not simply a reflection of their radiosensitivity, we gave iso-survival radiation doses to SV40-transformed fibroblasts of two AT and one control cell lines. The two AT cell lines exited from the G2/M-phase block more slowly than control cells after each dose tested. This implies that prolonged accumulation in G2/M phase in AT cells is not directly related to radiosensitivity as measured by clonogenic survival, but that factors involved in the exit from G2 phase after irradiation may be abnormally regulated. We found that G2-phase arrest of AT cells did not necessarily result in a fatal consequence in the first cell cycle after irradiation. Furthermore, G2-phase arrest did not lead to detectable DNA fragmentation characteristic of apoptosis as judged by gel electrophoresis.

[Observation on the action of extractum semen Persicae on anti-fibrosis of liver]

It was observed that Extractum Semen Persicae acted obviously on hepatic fibrosis induced by CCl4. Through promoting the degradation of collagens type I, II, IV, VI and fibronectin, ESP has proved helpful in markedly reducing the fibrous septa composed of both collagenous and reticular fibers as well as in repairing the structure of hepatic tissues.

Genetic diversity and multilocus associations in Cunninghamia lanceolata (Lamb.) Hook from The People's Republic of China

Open-pollinated seeds were assayed for allozyme polymorphisms at 24 loci to assess genetic diversity and multilocous associations in 16 populations of Cunninghamia lanceolata (Lamb.) Hook in the People's Republic of China. On average, the percentage of polymorphic loci was 88.0, the number of alleles per locus was 3.0, and the expected heterozygosity was 0.394. The distribution of genetic diversity was not correlated with the geographic and climatic variables of the populations. However, allele frequencies correlated linearly with the mean annual temperature of the populations at Mdh-1, Mdh-2, Mnr-2, Pgi-1, and Skdh-1 and with the altitude of the populations at Aph-4 and 6Pg-2. Of the total gene diversity 6% was attributed to among-population differentiation; 94% resided within populations. Two-locus gametic disequilibria were found in 15 of the 16 populations, and higher-order gametic disquilibria were significant in most populations. The gametic disequilibria did not correlate with geographic and climatic variables. The results suggest that population subdivision, founder effect, occurrence across diverse environments, a mating system dominated by inbreeding, and historical events from 2000 years of cultivation are contributing factors in the generation and maintenance of the multilocus genetic structure in this conifer.

Ataxia-telangiectasia: flow cytometric cell-cycle analysis of lymphoblastoid cell lines in G2/M before and after gamma-irradiation

It has been estimated that 1 to 3% of the general population may be ataxia-telangiectasia (A-T) heterozygotes and hypersensitive to conventional doses of radiation. We attempted to identify heterozygotes by evaluating the proportion of cells in various phases of the cell cycle in response to irradiation. This was accomplished by using flow cytometry to study lymphoblastoid cell lines (LCLs) from 14 A-T homozygotes, 17 genotypic A-T heterozygotes, and 18 normal individuals, including 10 genotypic normals. The LCLs were exposed to 2-gRay radiation and were analyzed after 24 hr along with nonirradiated controls. The difference between the percentage of cells in G2/M with and without irradiation after 24 hr ranged, respectively, from: 12.0 to 31.5% (mean = 18.7 +/- 5.5) for A-T homozygotes; 6.7 to 19.3% (mean = 12.5 +/- 3.8) for A-T heterozygotes; and -1.5 to 12.4% (mean = 6.4 +/- 3.2) for normals. A cut-off region of 9.6 to 13.2% defined by one standard deviation above the mean for normals and one standard deviation below the mean for A-T homozygotes served as the grey zone between normals and A-T heterozygotes or homozygotes. Two of the 18 normals overlapped with the grey zone. Four of 17 heterozygotes were within the normal range; seven fell within the grey zone. This may reflect nongenetic variables, such as the status of the LCLs at the time of testing. Flow cytometry cell-cycle analysis on irradiated LCLs is a useful adjunctive test for establishing a diagnosis of A-T in questionable cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Radiosensitivity of ataxia-telangiectasia, X-linked agammaglobulinemia, and related syndromes using a modified colony survival assay

We used a modified colony survival assay to measure the sensitivity to ionizing radiation of more than 50 lymphoblastoid cell lines from normal individuals and from patients with ataxia-telangiectasia, Nijmegen breakage syndrome variants, and X-linked agammaglobulinemia. All of these disorders are associated with an increased frequency of cancer. Lymphoblastoid cell lines from patients with ataxia-telangiectasia complementation groups A, C, D, and E; ATFresno; Nijmegen breakage syndrome variants V1 and V2; and X-linked agammaglobulinemia showed marked radiosensitivity, whereas ataxia-telangiectasia heterozygotes were similar to controls. Friedreich's ataxia is not associated with increased cancer risk; lymphoblastoid cell lines from two such patients showed normal radiosensitivity. Taken together, these results suggest that some forms of X-ray sensitivity and cancer susceptibility share a common mechanism, such as an enzyme that is necessary both for the repair of radiation damage to DNA and for gene rearrangements during V(D)J recombination.

Hepatic choriocarcinoma in a neonate: MR appearance

We present the MR findings of hepatic choriocarcinoma in a 2-week-old infant. Two masses of heterogeneous signal intensity were evident; one was an extensive mass on the left side of the liver and the other was a "daughter" nodule in the right lobe. Peripheral portions of the masses were hyperintense on T1-weighted imaging (T1WI) and T2-weighted imaging (T2WI) suggesting subacute hemorrhage. Central portions of the masses were hypointense on T1WI and bright on T2WI. T1-weighted postgadolinium imaging showed peripheral enhancement of both tumor nodules. The infant's mother had normal serum beta-human chorionic gonadotropin levels and pelvic CT.

The influence of delayed renal allograft function on long-term outcome in the cyclosporine era

The influence of delayed renal graft function on long-term allograft outcome remains uncertain. All 495 cyclosporine treated cadaver donor renal transplants within a single center were analyzed with respect to dialysis dependence in the early posttransplant period. When compared with immediate allograft function, dialysis dependence for more than one week posttransplant was associated with prolonged cold ischemia time (27 +/- 11 vs 32 +/- 12 hours), cytotoxic antibodies > 30% (14% vs 25%), black race (29% vs 41%), increased incidence of acute rejection in the first year posttransplant (31% vs 67%) and inferior 1-year (85% vs 52%) and 5-year (68% vs 33%) graft survival among primary transplants. No adverse effect however was noted on renal function in long-term survivors.

The influence of donor age on function of renal allografts from live related donors

To assess the influence of donor age on renal allograft outcome, we retrospectively analyzed all 169 consecutive cyclosporine-treated live related donor kidney transplants, of whom 40 were HLA identical siblings. All recipients were similar with respect to demographic and immunologic characteristics. Incidence of rejection episodes and graft survival rates at 1 and 5-year posttransplant were independent of donor age. Best renal function, as assessed by the mean of the lowest 3 serum creatinine concentration levels in the first 2 months posttransplant correlated positively with donor age, particularly among HLA mismatched male recipients (r = 0.4, P < 0.002). Short and intermediate term renal function was inferior, but stable in the older donor recipient group when compared to the younger cohort. Mean serum creatinine levels at 5 years in recipients of kidneys from older donors (age > 55 years) was 2.6 mg/dl compared to 1.7 and 1.9 mg/dl in recipients of kidneys from donors between the ages of 18-39 and 40-54 years, respectively (P < 0.001). In view of the universal shortage of organs and the negligible morbidity to the donors, our results should not discourage the use of kidneys from elderly (age > 55 years) donors.