Growth of carbon nanotubes at low powers by impedance-matched microwave plasma enhanced chemical vapor deposition method

A solo carbon nanotube (CNT) was successfully grown on nickel electrodes by a microwave plasma enhanced chemical vapor deposition (MPECVD) method equipped with an impedance-matched substrate holder with the reaction gases composed of hydrogen (H2), carbon dioxide (CO2), and methane (CH4) mixtures. An introduction of carbon dioxide gas before CNTs growth, the substrate temperature can easily be reached above 610 degrees C even heated at a low microwave power. This can be enunciated from fact that carbon dioxide inherits with higher bond energy for molecular dissociation, lower thermal conductivity, and higher heat capacity in comparing to other gases. The electron field emissions for randomly aligned CNTs and well-aligned CNTs grown by MPECVD and by radio frequency assisted hot-filament methods, respectively, are measured and compared. The higher field emission characteristic of the randomly aligned CNTs is presumed to be due to the protruded CNTs, which inheriting with less screening effect and manifesting with defects are crucial to play the effective emission sites.

Prospective trial of resurfaced patellaversus non-resurfaced patella in simultaneous bilateral total knee replacement

INTRODUCTION

A prospective trial was carried out in simultaneous bilateral total knee replacement to compare the outcome of resurfaced versus non-surfaced patella.

METHODS

Thirty-five patients between 1997 and 2002 had simultaneous bilateral total knee replacement with resurfaced patella on the left and non-resurfaced patella on the right knee using the same implant in both.

RESULTS

There were 29 females and six males with a mean age of 65.3 years. Mean follow-up was 3.18 years. There was no significant difference between the resurfaced and non-resurfaced knees with respect to the overall Knee Society clinical score (p = 0.093 preoperative, 0.310 postoperative) or the pain (p = 0.715 preoperative, 0.395 postoperative) or function subscores (p = 0.126 preoperative, 0.317 postoperative). The postoperative range of motion was 109 and 110 degrees for the resurfaced patella and non-resurfaced patella respectively (p = 0.894). The post-operative knee scores between patients with or without pre-operative anterior knee pain (p = 0.238) and between those who were obese and non-obese (p = 0.387) were not significantly different. 82.9% of patients felt that the resurfaced knee and 80% felt that the non-resurfaced knee were much better than before. There was no major preference for either knee for climbing stairs and getting out of chair.

CONCLUSION

The functional and symptomatic outcome of total knee replacement with or without patella resurfacing is the same in the local population. Also, the present study demonstrated no evidence that the weight of the patient or the presence of preoperative anterior knee pain should be considered as factors in the decision to resurface the patella.

Functional specialization and evolution of leader proteinases in the family Closteroviridae

Members of the Closteroviridae and Potyviridae families of the plant positive-strand RNA viruses encode one or two papain-like leader proteinases. In addition to a C-terminal proteolytic domain, each of these proteinases possesses a nonproteolytic N-terminal domain. We compared functions of the several leader proteinases using a gene swapping approach. The leader proteinase (L-Pro) of Beet yellows virus (BYV; a closterovirus) was replaced with L1 or L2 proteinases of Citrus tristeza virus (CTV; another closterovirus), P-Pro proteinase of Lettuce infectious yellows virus (LIYV; a crinivirus), and HC-Pro proteinase of Tobacco etch virus (a potyvirus). Each foreign proteinase efficiently processed the chimeric BYV polyprotein in vitro. However, only L1 and P-Pro, not L2 and HC-Pro, were able to rescue the amplification of the chimeric BYV variants. The combined expression of L1 and L2 resulted in an increased RNA accumulation compared to that of the parental BYV. Remarkably, this L1-L2 chimera exhibited reduced invasiveness and inability to move from cell to cell. Similar analyses of the BYV hybrids, in which only the papain-like domain of L-Pro was replaced with those derived from L1, L2, P-Pro, and HC-Pro, also revealed functional specialization of these domains. In subcellular-localization experiments, distinct patterns were observed for the leader proteinases of BYV, CTV, and LIYV. Taken together, these results demonstrated that, in addition to a common proteolytic activity, the leader proteinases of closteroviruses possess specialized functions in virus RNA amplification, virus invasion, and cell-to-cell movement. The phylogenetic analysis suggested that functionally distinct L1 and L2 of CTV originated by a gene duplication event.

Bilateral synchronous renal oncocytoma: a case report and review

INTRODUCTION

Renal oncocytoma is a rare benign tumour.

CLINICAL PICTURE

A 73-year-old man presented with bilateral renal tumours, suggestive of renal cell carcinoma (RCC). Nephron-sparing surgery (NSS) and radical nephrectomy were performed. Both specimens revealed renal oncocytoma on final histology. A review of nephrectomy specimens showed 4 other solitary oncocytomas out of 250 RCCs over the period 1991 to 2000. Diagnosis of oncocytoma could only be firmly established by careful histological evaluation to exclude RCC.

TREATMENT

Renal oncocytoma carries a good prognosis. The use of NSS for synchronous bilateral renal masses is highlighted.

CONCLUSION

NSS is recommended for renal oncocytoma wherever possible.

Leader proteinase of the beet yellows closterovirus: mutation analysis of the function in genome amplification

The beet yellows closterovirus leader proteinase (L-Pro) possesses a C-terminal proteinase domain and a nonproteolytic N-terminal domain. It was found that although L-Pro is not essential for basal-level replication, deletion of its N-terminal domain resulted in a 1, 000-fold reduction in RNA accumulation. Mutagenic analysis of the N-terminal domain revealed its structural flexibility except for the 54-codon-long, 5'-terminal element in the corresponding open reading frame that is critical for efficient RNA amplification at both RNA and protein levels.

Perioperative and rehabilitative outcomes after amputation for ischaemic leg gangrene

INTRODUCTION

Amputation of the severely ischaemic leg is often done when limb salvage is not possible or the patient is not fit enough for it. It is therefore important to determine the natural history of these amputees as our understanding of this will have significant impact on decision making. The aim of this study was to determine the early and late morbidity and mortality rates and rehabilitative outcome of these patients with lower limb amputation for end-stage arterial occlusive disease.

MATERIALS AND METHODS

A retrospective study was done on 72 patients with 77 lower limb amputations for critical limb ischaemia (rest pain, gangrene, ischaemic ulcers) from 1993 to 1998 at the Singapore General Hospital.

RESULTS

The mean age of the amputees was 69.7 years. Fifty-one per cent of the patients were male. Forty-five (58%) of the amputations were performed because the limb vasculature was not reconstructable, 12 (16%) because the limbs were too late for salvage and the remaining 20 (26%) because vascular reconstruction failed. Below knee amputations account for 63.6% of all amputations, above knee amputations account for 35.1% and through knee amputations account for 1.3%. Fifteen (19%) of the amputations had wound infection and 8% of amputations required re-amputation at a higher level for wound infection or failure of wound healing. The contralateral amputation rate was 21%. The 30-day mortality for all amputations was 11.1% and the commonest cause was acute myocardial infarction which accounted for 37.5%. Vascular reconstruction did not alter the overall or perioperative mortality rate. Cumulative survival figures showed that at the end of four years, only 38% of all amputees were still alive. 52.5% of amputees were wheelchair-bound, only 15% were household ambulators and 27.5% were community ambulators. Of all the patients with unilateral below knee amputations, 40% could walk out of home while only 20% of unilateral above amputations and 12.5% of bilateral below knee amputations could walk out of home.

CONCLUSION

Early and late rehabilitation after amputation for critical limb ischaemia remain poor and efforts should be made to salvage critically ischaemic limbs wherever possible in patients who are fit enough.

Sufficient length of a poly(A) tail for the formation of a potential pseudoknot is required for efficient replication of bamboo mosaic potexvirus RNA

RNAs transcribed from a full-length infectious cDNA clone of the bamboo mosaic potexvirus (strain O) genome, pBaMV-O, were infectious to Nicotiana benthamiana plants. Mutant genomes in which the poly(A) tail is absent or replaced by a 3' tRNA-like structure from turnip yellow mosaic virus RNA failed to amplify detectably in N. benthamiana protoplasts. No amplification was detected in protoplasts inoculated with transcripts containing 4, 7, or 10 adenylate residues at the 3' end, whereas transcript inocula with 15 adenylate residues resulted in coat protein accumulation to a level 26% of that resulting from inoculation with transcripts with 25 adenylate residues (designated as wild type). Coat protein accumulation levels of 69 and 98% relative to wild type were observed after inoculation of protoplasts with transcripts bearing poly(A) tails 18 and 22 nucleotides long, respectively. The presence of a putative 3' pseudoknot structure including at least 13 adenylate residues of the 3'-terminal poly(A) tail was supported by enzymatic and chemical structural analysis. The functional relevance of this putative pseudoknot was tested by mutations that affected basepairing within the pseudoknot. These results support the existence of functional 3' pseudoknot that includes part of the 3' poly(A) tail.

Protein Concentration Dependence of Calcium Binding to Prothrombin Fragment-1

Calcium binds to prothrombin and prothrombin fragment-1 with apparent positive cooperativity. It has previously been suggested that the cooperativity is induced by a conformation change in the protein. Another process which can induce cooperativity is ligand induced self-association. Calcium has been shown to induce dimerization in prothrombin and fragment-1. If such an intermolecular process is responsible for the apparent cooperativity, the calcium binding should become non-cooperative at the limit of zero protein concentration. The protein concentration dependence of calcium binding to fragment-1 was investigated using ultraviolet difference spectroscopy and the Hummel-Dryer equilibrium binding technique. A maximum of 10 sites was found on fragment-1 at high calcium concentration (10 μM). The maximum in the Scatchard plot was observed to decrease at fragment-l concentrations less than 10 μM. The difference spectral data was analyzed utilizing the equilibrium binding data. The apparent dissociation constant ob tained from difference spectral titrations is protein concentration dependent. At low protein concentration (1-2 μM) the maximal spectral change occurs with 2 or less Caions bound, while at higher concentrations (50-100 μM), the maximum is reached after ~5 sites are filled.

(Supported by HL14l47, Specialized Center of Research on Thrombosis, NHLBI).