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PubMed1996

The IPEMB code of practice for the determination of absorbed dose for x-rays below 300 kV generating potential (0.035 mm Al-4 mm Cu HVL; 10-300 kV generating potential). Institution of Physics and Engineering in Medicine and Biology.

This new code of practice for the determination of absorbed dose for x-rays below 300 kV has recently been approved by the IPEMB and introduces the following changes to the previous codes: (i) The determination of absorbed dose is based on the air kerma determination (exposure measurement) method. (ii) An air kerma calibration factor for the ionization chamber is used. (iii) The use of the F (rad/röentgen) conversion factor is abandoned and replaced by the ratio of the mass-energy absorption coefficients of water and air for converting absorbed dose to air to absorbed dose to water. New values for ratios of these coefficients are recommended. Perturbation and other correction factors are incorporated in the equations. (iv) New backscatter factors are recommended. (v) Three separate energy ranges are defined, with specific procedures for each range. These ranges are: (a) 0.5 to 4 mm Cu HVL; for this range calibration at 2 cm depth in water with a thimble ion chamber is recommended. (b) 1.0 to 8.0 mm AI HVL; for this range calibration in air with a cylindrical ion chamber and the use of tabulated values of the backscatter factor are recommended. (c) 0.035 to 1.0 mm AI HVL; for this range calibration on the surface of a phantom with a parallel-plate ionization chamber is recommended.

Humans↗
PubMed2005

Addendum to the IPEMB code of practice for the determination of absorbed dose for x-rays below 300 kV generating potential (0.035 mm Al-4 mm Cu HVL).

This addendum to the code of practice for the determination of absorbed dose for x-rays below 300 kV has recently been approved by the IPEM and introduces three main changes: (i) Due to a lack of available data the original code recommended a value of unity for k(ch) in the very-low-energy range (0.035-1.0 mm Al HVL). A single table of k(ch) values, ranging from 1.01 to 1.07, applicable to both designated chamber types is now presented. (ii) For medium-energy x-rays (0.5-4 mm Cu HVL) methods are given to determine the absorbed dose to water either at 2 cm depth or at the surface of a phantom depending on clinical needs. Determination of the dose at the phantom surface is derived from an in-air measurement and by extending the low-energy range up to 4 mm Cu HVL. Relevant backscatter factors and ratios of mass energy absorption coefficients are given in the addendum. (iii) Relative dosimetry: although not normally forming part of a dosimetry code of practice a brief review of the current literature on this topic has been added as an appendix. This encompasses advice on techniques for measuring depth doses, applicator factors for small field sizes, dose fall off with increasing SSD and choice of appropriate phantom materials and ionization chambers.

Humans↗
PubMed1996

Hemodynamic evaluation of 23 mm Pericarbon and 23 mm Hancock II bioprostheses in the aortic position at mid-term follow up.

BACKGROUND AND AIMS OF THE STUDY: Pericardial xenografts were introduced for clinical use following evidence of their good hemodynamic characteristics in laboratory tests; however, their efficiency in comparison with porcine valves has not been fully assessed. Pericarbon, a new type of pericardial bioprosthesis, has been recently developed in order to provide better hemodynamic performances and longer durability than such bioprostheses currently in use. METHODS: Fifteen patients operated on for aortic valve replacement with a 23 mm Pericarbon and a sex- and age-matched group operated on with a 23 mm Hancock II bioprosthesis were submitted to echocardiographic and Doppler examinations in order to compare the hemodynamic performance of the two devices. RESULTS: Peak transvalvular gradients for Pericarbon and Hancock II bioprostheses (38.9 +/- 13.0 vs. 33.9 +/- 13.0 mmHg; p = 0.294) and mean transvalvular gradients (24.7 +/- 7.6 vs. 20.8 +/- 9.9 mmHg, p = 0.24) showed no significant difference. However, the indexed effective prosthetic dynamic area was significantly larger for the Hancock II device (0.73 +/- 0.14 vs. 0.62 +/- 0.13 cm2; p < 0.05). CONCLUSIONS: When installed as 23 mm pericardial bioprostheses, the Pericarbon device appears not to demonstrate superior hemodynamic performance to that of the Hancock II; however, additional studies are needed to provide a definitive conclusion.

Aged↗
PubMed1975

Comparison of observer performance with 16 mm cinefluorography and 70 mm camera fluorography in coronary arteriography.

Clinical 16 mm cinefluorography and 70 mm camera fluorography were compared in 30 unselected patients undergoing coronary arteriography. Accuracy in detecting coronary arterial stenosis and collateral vessels and in assessing the degree of stenosis was similar with the two techniques. With both methods, there were significant inter- and intraobserver differences in estimating the degree of stenosis. These differences indicate that coronary arteriography is only a semiquantitative method for making decisions about treatment, prognosis and follow-up of patients. The use of more than one observer increases the likelihood that stenotic lesions will be detected. Interobserver variation in detecting collateral circulation is small.

Adult↗
PubMed2001

Comparison of immediate and one-year outcome after coronary angioplasty of narrowing < 3 mm with those > or =3 mm ( the National Heart, Lung, and Blood Institute Dynamic Registry).

Balloon angioplasty of small coronary artery lesions has been associated with lower success and higher complication rates than large coronary artery lesions. This study evaluates the in-hospital and 1-year outcome of the treatment of small coronary artery lesions in the modern era of interventional cardiology and compares it with the outcome of treating large coronary artery lesions. Of 1,658 patients with a single lesion treated from July 1997 to February 1998 in the National Heart, Lung, and Blood Institute (NHLBI) Dynamic Registry, there were 587 patients with small coronary artery lesions (<3 mm) and 1,071 patients with large coronary artery lesions (> or =3 mm). Success, in-hospital, and 1-year outcomes between both groups were compared. Patients with lesions in small coronary arteries were more often women, insulin-treated diabetics, and had undergone more prior coronary bypass graft surgery. Conventional angioplasty alone was performed more often and angioplasty with stents was performed less often in the small coronary artery than in the large coronary artery group. Angiographic success was slightly lower in the small coronary artery group (94.2% vs 96.9%, p <0.05). Periprocedural and in-hospital complication rates were similar in both groups. Likewise, at 1-year follow-up, major adverse cardiac events including death, myocardial infarction, and coronary artery bypass graft surgery were relatively low and comparable between the 2 groups, although patients with small coronary arteries were more likely to undergo repeat revascularization (17.4% vs 13.6%, p <0.05). Treatment of lesions in small coronary arteries in the modern era is associated with high success and low complication rates, comparable to the treatment of large coronary artery lesions, although the incidence of repeat revascularization was significantly greater at follow-up even if stents were used.

Aged↗
PubMed1994

Postoperative astigmatism after no-stitch, small incision cataract surgery with 3.5 mm and 4.5 mm incisions.

We studied postoperative astigmatism in 107 patients who were followed for 12 months after phacoemulsification and posterior chamber lens implantation. A scleral incision of 3.5 mm was used in Group A patients and one of 4.5 mm in Group B patients. In both groups a no-stitch wound closure technique was used. A high correlation between preoperative and 12-month postoperative height and time shift of keratometric values was found. In both groups the mean difference was less than 0.60 diopters (D). The mean postoperative cylinder increase was less than 0.50 D; it was less than 0.25 D after six months. The induced astigmatism was confirmed by three different methods. Immediately after surgery, a negative induced astigmatism was found in both groups. After 12 months, induced astigmatism in Group A was -0.37 D and in Group B, -0.67 D. Immediately after surgery there was an axis change; a decrease of with-the-rule astigmatism occurred concurrently with an increase toward oblique and against-the-rule astigmatism. This axis change was somewhat evident after 12 months.

Astigmatism↗
PubMed1990

Early results with the 8 mm and 9 mm HEMA disc intraocular lens.

This study presents our experience with 34 HEMA disc intraocular lenses implanted in the capsular bag. Despite the small number of cases and the relatively short mean postoperative follow-up of nine months, the results show a low incidence of uveitis and capsular fibrosis and excellent biocompatibility. The following complications were observed: four luxations of the 8 mm lens and one of the 9 mm lens in the anterior chamber. A visual acuity of 20/20 to 20/40 was obtained in 32 patients (94%).

Aged↗
PubMed1989

Comparison of the unwanted optical images produced by 6 mm and 7 mm intraocular lenses.

Unwanted optical images are noticed by a surprisingly large number of patients following cataract extraction with implantation of posterior chamber intraocular lenses (IOLs). These images are caused by the positioning holes, lens edge, or laser ridge. We studied 550 eyes in which one of seven different IOLs was inserted. The IOLs varied in optic diameter, the presence or absence of positioning holes or a laser ridge, the use of partial depth holes or placement of positioning holes in tabs outside the optical zone. We determined that unwanted optical images could practically be eliminated by using a 7 mm optic without positioning holes. This study also demonstrated that partial depth holes offer no advantage over full thickness holes for reducing unwanted optical images and that positioning holes, even on a 7 mm optic, produce a significant number of complaints.

Equipment Design↗
PubMed2000

Oxalato-bridged dinuclear complexes of Cr(III) and Fe(III): synthesis, structure, and magnetism of [(C2H5)4N]4[MM'(ox)(NCS)8] with MM' = CrCr, FeFe, and CrFe.

A new series of homo- and heterometallic oxalato-bridged dinuclear compounds of formulas [Et4N]4[MM'(ox)(NCS)8] ([Et4N]+ = [(C2H5)4N]+; ox = C2O4(2-)) with MM' = Cr(III)-Cr(III) (1), Fe(III)-Fe(III) (2), and Cr(III)-Fe(III) (3) is reported. They have been structurally characterized by infrared spectra and single-crystal X-ray diffraction. The three compounds are isostructural and crystallize in the orthorhombic space group Cmca with Z = 8, a = 16.561(8) A, b = 13.481(7) A, and c = 28.168(8) A for 1, a = 16.515(2) A, b = 13.531(1) A, and c = 28.289(4) A for 2, a = 16.664(7) A, b = 13.575(6) A, and c = 28.386(8) A for 3. The structure of 3 is made up of a discrete dinuclear anion [CrFe(ox)(NCS)8]4- and four disordered [Et4N]+ cations, each of them located on special positions. The anion, in a crystallographically imposed C2h symmetry, contains metal cations in distorted octahedral sites. The Cr(ox)Fe group, which is planar within 0.02 A, presents an intramolecular metal-metal distance of 5.43 A. Magnetic susceptibility measurements indicate antiferromagnetic pairwise interactions for 1 and 2 with J = -3.23 and -3.84 cm-1, respectively, and ferromagnetic Cr-Fe coupling with J = 1.10 cm-1 for 3 (J being the parameter of the exchange Hamiltonian H = -2JS1S2). The ESR spectra at different temperatures confirm the magnetic susceptibility data.

Journal Article↗
PubMed2003

Macrophage inflammatory protein-1 alpha is produced by human multiple myeloma (MM) cells and its expression correlates with bone lesions in patients with MM.

Macrophage inflammatory protein-1 alpha (MIP-1alpha) is a chemokine primarily associated with bone absorption. We examined whether MIP-1alpha was produced by purified fresh tumour cells isolated from bone marrow samples from 31 multiple myeloma (MM) patients. High levels of MIP-1alpha were found in supernatants of myeloma cell cultures. Immunohistochemical staining showed MIP-1alpha in the cytoplasm of myeloma cells. MIP-1alpha mRNA expression was detected in 18 of 31 patients. Bone lesions were seen in 16 of the 18 MIP-1alpha-positive patients but only in six of the 13 MIP-1alpha-negative patients (P = 0.0097,chi2-test). The data indicate that MIP-1alpha is produced by myeloma cells and possibly plays a role in the pathogenesis of bone lesions in MM patients.

Aged↗
PubMed1992

Laser lithotripsy of pancreatic and biliary stones via 3.4 mm and 3.7 mm miniscopes: first clinical results.

The pulsed dye laser is safe and effective in lithotripsy of biliary and pancreatic ductal stones, however delivery of the laser energy to the site of the calculi is technically difficult. A 3.4 mm miniscope inserted through a standard duodenoscope was used for transpapillary laser application under direct vision in one patient with an impacted pancreatic stone and in three patients with bile duct stones not amenable to treatment by routine endoscopy. Lithotripsy and ductal clearance was achieved in 3 of the 4 patients within a single treatment session. Percutaneous transhepatic laser lithotripsy via a 3.7 mm miniscope succeeded in the patient in whom the peroral approach had failed and in two further patients with bile duct stones not accessible by a retrograde approach. There were no major complications. The miniscopes provide an appropriate direct visual control for laser lithotripsy of pancreatobiliary calculi. This approach using miniscopes seems to be an effective, minimally invasive and time-saving alternative to conventional endoscopic laser lithotripsy.

Adult↗
PubMedDate not supplied

A comparison of the Synthes 4.5-mm cannulated screw and the Synthes 4.5-mm standard cortex screw systems in equine bone.

OBJECTIVE: To determine risk of failure of the Synthes 4.5-mm cannulated screw system instrumentation in equine bone and to compare its application with the Synthes 4.5-mm standard cortex screw system. STUDY DESIGN: The maximum insertion torque of the cannulated and standard cortex screw systems were compared with the ultimate torsional strengths of the equipment. Pullout strength and ultimate tensile load of cannulated and standard cortex screws were also determined. SAMPLE POPULATION: Paired equine cadaver third metacarpal and third carpal bones. METHODS: Maximum insertion torque and ultimate torsional strengths were determined by using an axial-torsional, servohydraulic materials testing system and a hand-held torquometer. Pullout tests were performed by using a servohydraulic materials testing system. RESULTS: Maximum insertion torque of all cannulated instrumentation was less than ultimate torsional strength at all locations (P < .05). Maximum insertion torques of cannulated taps and screws were greater than for standard taps and screws in the third carpal bone (P < .002). Pullout strength of the cannulated screws was less than the standard cortex screws at all sites (P < .001). Cannulated screws broke before bone failure in all but one bone specimen. CONCLUSIONS: The risk of cannulated instrument or screw failure during insertion into bone is theoretically low. The relatively low pullout strength of the cannulated screws implies that the interfragmentary compression achievable is likely to be less than with standard cortex screws. CLINICAL RELEVANCE: The relatively low pullout strength of the cannulated screw suggests that its risk of failure during fracture repair is greater than with the standard cortex screw.

Animals↗
PubMed1994

Performance of a 3.2-mm to 6-mm adaptor.

A study was undertaken to evaluate the performance of a 366-08 adaptor that adapts an in-line bipolar 3.2-mm connector to a 6-mm pulse generator connector. A total of 14 adaptors were implanted in individual patients. Eight of the 14 adaptors failed, an additional failure is probable. The average follow-up time was 32.1 months. The most likely cause of failure was the spring-loaded mechanism of the adaptor, which fatigues with time. All eight of the documented failures presented with loss of capture and were accompanied by increased measured lead impedances. In addition, some failed systems demonstrated loss of sensing. As a result, prophylactic replacement of ventricular lead systems incorporating this adaptor would be advisable. Otherwise, more frequent monitoring with lead impedance measurements may suffice.

Aged↗
PubMed1990

MM 47761 and MM 49721, glycopeptide antibiotics produced by a new strain of Amycolatopsis orientalis. Isolation, purification and structure determination.

Two glycopeptide antibiotics MM 47761 and MM 47921 have been isolated from Amycolatopsis orientalis NCIB 12608. Fermentation conditions for their production, and methods for their isolation are described. The metabolites have been characterised by physio-chemical and biological properties and the structure determined by a combination of chemical degradation, COSY and NOE NMR studies. Both metabolites showed good antibacterial activity against Gram-positive organisms.

Actinomycetales↗
PubMed1991

MM 55266 and MM 55268, glycopeptide antibiotics produced by a new strain of Amycolatopsis. Isolation, purification and structure determination.

Two novel glycopeptide antibiotics MM 55266 and MM 55268 containing fatty acid acyl functions, and of molecular formula C86H89N8O35Cl5 and C87H91N8O35Cl5, respectively, have been isolated and identified from a complex produced by Amycolatopsis sp. NCIB 40089. Fermentation conditions for their production, and methods for their isolation are described. Structures have been deduced by use of COSY and NOE NMR techniques and supported by chemical degradation studies. Both glycopeptides possessed good antibacterial activity against Gram-positive organisms.

Actinomycetales↗
PubMed2000

Clinical and hemodynamic evaluation of 21 mm and 23 mm Cryolife-O'Brien stentless bioprostheses implanted in the aortic position.

BACKGROUND: The aim of this study was to investigate early and mid-term results after aortic valve replacement with Cryolife-O'Brien stentless bioprosthesis, model 300. METHODS: Records of 59 patients who received a 21 or 23 mm (Group A) aortic Cryolife-O'Brien stentless valve were retrospectively reviewed and compared to 54 patients who received a valve > or = 25 mm (Group B). Group A patients were mainly female (p < 0.001), were older (p = 0.034), had dominant aortic stenosis (p = 0.011), and a smaller (p < 0.001) body surface area. Effective orifice area index was larger (p = 0.041) and left ventricular mass index higher (p = 0.024) in Group B. RESULTS: The actuarial survival at 5.5 years was 94.9 +/- 2.3% and 92.5 +/- 4.3% in Group A and B respectively (p = NS). The actuarial freedom from all events was 85.1 +/- 6.1% and 88.2 +/- 5.2% in Group A vs Group B respectively (p = NS). At late echocardiographic studies performed between 4 and 42 months (mean 27.3 +/- 6.1 months) postoperatively, peak and mean gradients decreased and effective orifice area index increased over the follow-up period (p = NS between groups). Left ventricular mass index decreased by 25% (p < 0.001) in Group A and by 20% (p < 0.001) in Group B from preoperatively and a further 13% (p = 0.034) and 8.5% (p = 0.004), respectively, from the early to the late study. No significant difference in left ventricular mass regression was noticed between groups (p = NS). CONCLUSIONS: The Cryolife-O'Brien porcine stentless bioprosthesis showed satisfactory mid-term results and may represent a good choice for patients with a small aortic annulus selected for a biological valve.

Aged↗