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PubMed1996

Adenomyosis: specificity of 5 mm as the maximum normal uterine junctional zone thickness in MR images.

OBJECTIVE: Our objective was to investigate the specificity of the criterion stating that a diagnosis of adenomyosis can be made confidently from MR images of the uterus when the junctional zone is thicker than 5 mm. SUBJECTS AND METHODS: Twenty clinically normal women volunteers (chosen by strict criteria) underwent MR imaging of the uterus. Images were independently evaluated by two experienced observers who measured the greatest thickness of the junctional zone in the anterior, posterior, right and left walls of the uterine corpus and at the top of the fundus. RESULTS: The mean value of the greatest junctional zone thickness (averaged for both observers) was 4.4 +/- 2.1 mm (mean +/- SD, range, 1-9 mm) for the anterior and posterior walls of the corpus, 4.3 +/- 2.1 mm (range, 1-10 mm) for the right and left walls, and 2.3 +/- 1.1 mm (range, 1-5 mm) for the fundus. At least one region of the junctional zone was found to be thicker than 5 mm by at least one observer in 13 (65%) of the 20 subjects; at least one region was found to be thicker than 5 mm by both observers in eight (40%) subjects. At least two regions were measured as thicker than 5 mm by both observers in six (30%) subjects. Serial studies of three volunteers showed transient irregular focal or diffuse thickening (up to 12 mm) of the junctional zone and focal myometrial bulging, probably due to myometrial contractions. CONCLUSION: Our results suggest that if a diagnosis of adenomyosis is based solely on junctional zone thickness in MR images, 5 mm should not be assumed as the upper limit of normal, because this assumption may result in a high false-positive rate.

Adolescent↗

PubMedDate not supplied

Survival estimates and risk factors for failure with 6 x 5.7-mm implants.

PURPOSE: Short dental implants facilitate prosthetic restoration in the setting of limited alveolar bone height. The study objectives were to (1) estimate the 1-year survival of Bicon 6 x 5.7-mm implants, (2) compare the 1-year survival of 6 x 5.7-mm implants with that of non-6 x 5.7-mm implants, and (3) identify risk factors associated with implant failure. MATERIALS AND METHODS: A retrospective cohort study design was used. The sample was composed of patients who had received at least one 6 x 5.7-mm implant. Predictor variables were categorized as demographic, health status, anatomic, implant-specific, prosthetic, perioperative, and reconstructive. The outcome variable was implant failure, defined as explantation. Appropriate descriptive, bivariate, and multivariate survival statistics were computed. RESULTS: The sample was composed of 35 patients in whom 172 implants had been placed (45 of which were 6 x 5.7-mm). The 1-year survival rates for 6 x 5.7-mm and non-6 x 5.7-mm implants were 92.2% and 95.2%, respectively (P = .76). After adjusting for covariates in a multivariate model, implant size was not associated with failure (P = .95). DISCUSSION: The comparable survival estimates for 6 x 5.7-mm implants and non-6 x 5.7-mm implants in this study suggested that 6 x 5.7-mm implants can become osseointegrated and bear a functional load after placement. CONCLUSIONS: The survival of 6 x 5.7-mm implants was comparable to that of non-6 x 5.7-mm implants.

Dental Implants↗

PubMed1989

Clinical and hemodynamic performance of the Ionescu-Shiley valve in the small aortic root. Results in 117 patients with 17 and 19 mm valves.

The Ionescu-Shiley pericardial valve was our bioprosthetic valve of choice between 1981 and 1985 for patients in whom the aortic anulus could not accept a valve larger than 19 mm in outer diameter or in whom the avoidance of warfarin sodium (Coumadin) was important. A series of 117 consecutive patients who received 17 or 19 mm valves for isolated aortic valve replacement or aortic valve replacement combined with coronary artery bypass grafting or other valvular procedures was analyzed. Overall, 74% of the patients were female, with a mean age of 70.9 years and a body surface area of 1.67 +/- 0.19 m2; 92.3% were in New York Heart Association class III-IV, and the operation was urgent or emergent in 46%. The operative mortality rate was 7.7%, with no deaths in patients undergoing isolated elective first-time aortic valve replacement. Mean follow-up for survivors was 2.5 years (10 to 62 months). There were 20 late deaths, of which three were valve related, three were due to sudden death or arrhythmias, and two were due to persistent heart failure. The actuarial survival rate at 5 years was 68%. Clinical follow-up revealed a low incidence of valve-related complications, and 96.4% of survivors were in class I-II. Postoperative echocardiography before hospital discharge revealed a maximum instantaneous gradient of 18.4 +/- 3.0 mm Hg in five patients having a 17 mm valve and 31.3 +/- 12.7 mm Hg in 20 patients having a 19 mm valve. Doppler echocardiography was performed in 22 patients at a mean follow-up of 39.3 +/- 11.7 months. The maximum instantaneous gradient was 25 +/- 17.2 mm Hg for 17 mm and 17.41 +/- 5.4 mm Hg for 19 mm valves at late follow-up. The effective orifice area was 0.85 +/- 0.1 cm2 for 17 mm and 1.21 +/- 0.21 cm2 for 19 mm valves. This study defines the normal range of Doppler echocardiographic transprosthetic gradients for the Ionescu-Shiley valve and confirms that low operative mortality and excellent clinical improvement can result from the use of small Ionescu-Shiley valves in elderly patients despite moderate postoperative transvalvular gradients.

Adult↗

PubMed1985

Induction of differentiation of cultured mouse monocytic leukemia cells (Mm-A) by inducers different from those of parent myeloblastic leukemia cells (M1).

Mouse monocytic Mm-A cells are a highly leukemogenic variant line of the monocytic and non-leukemogenic cell line Mm-1, which developed spontaneously from mouse myeloid leukemia M1 cells. Studies were made on whether Mm-A cells could be induced to differentiate further by agents that were effective for inducing differentiation of the parent M1 cells and other leukemic cells. Of the agents tested, butyrate, conditioned medium from concanavalin A-stimulated spleen cells, lipopolysaccharide (LPS) and N6,O2-dibutyryl adenosine 3'5'-cyclic-monophosphate (dbcAMP) significantly stimulated the lysozyme activity of Mm-A cells, which is one of the most characteristic biochemical markers of monocytes and macrophages. Butyrate was the most effective agent for increasing lysozyme production by Mm-A cells; culture with 0.5mM butyrate for 3 days increased lysozyme production by Mm-A cells about 50-fold. Inducers of M1 cell differentiation such as dexamethasone, 1 alpha,25-dihydroxyvitamin D3, arginase, and proteinous inducer did not increase the lysozyme activity. Butyrate also induced NBT reduction and stimulated other differentiation-associated functions, such as expressions of Fc receptors on the cell surface, immune phagocytosis and production of inducer for M1 cell differentiation. Its effect in stimulating differentiation of Mm-A cells was synergistic with that of dbcAMP or LPS. Incubation with butyrate inhibited the proliferation of Mm-A cells, about 0.3mM butyrate causing 50% inhibition. These results indicate that monocytic, leukemogenic Mm-A cells can be induced to differentiate further by butyrate and that the inducers of differentiation of Mm-A cells are markedly different from those of the parent myeloblastic M1 cells.

Animals↗

PubMed1999

Ectopic expression of (Mm)Kin17 protein inhibits cell proliferation of human tumor-derived cells.

To characterize the biological role of Kin17 protein, a mammalian nuclear protein which participates in the response to UV and ionizing radiation and binds to curved DNA, EBV-derived vectors carrying (Mm)Kin17 cDNA were constructed and transfected in tumorigenic cells harboring different p53 profiles (HeLa, H1299, and HCT116) and in immortalized HEK 293 cells. (Mm)Kin17 protein expression induced a tremendous decrease in cell proliferation of the three tumorigenic cell lines 2 weeks after transfection. Transfection of HEK 293 cells with an pEBVCMV(Mm)Kin17 plasmid gave rise to numerous (Mm)Kin17-expressing cells which constantly disappeared with time, preventing the establishment of (Mm)Kin17-expressing cells. Several independent clones were isolated from HEK 293 cells carrying a pEBVMT(Mm)Kin17 vector. The two clones described here (B223.1 and B223.2) exhibited different (Mm)Kin17 protein levels and displayed a gradual decrease in their proliferative capacities. In B223.1 cells, the basal expression of (Mm)Kin17 greatly reduced plating efficiency and cell growth. B223.1 cell morphology was altered, with numerous round-shaped cells whose spreading on the culture support was hampered. We observed giant multinucleated cells or cells containing micronuclei-like structures and/or multilobed nuclei. To conclude, (Mm)Kin17 overexpression reduced the proliferation of tumorigenic cells independently of their p53 status and modified cell growth and cell morphology of established HEK 293 cells producing (Mm)Kin17 protein. It is likely that (Mm)Kin17 may interfere with DNA replication.

Animals↗

PubMed2000

Comparison of optical zones in hyperopic laser in situ keratomileusis: 5.9 mm versus smaller optical zones.

PURPOSE: To compare the results of hyperopic laser in situ keratomileusis (LASIK) with a 5.9 mm optical zone (OZ) with those with smaller zones (4.4 to 5.5 mm). SETTING: Instituto de la Visión, Buenos Aires, Argentina. METHODS: The results of LASIK with a 5.9 mm OZ (147 cases) were compared with those in a previously reported group treated with OZs of 4.4 to 5.5 mm (679 cases). In the 5.9 mm group, 31.3% (46 eyes) had low hyperopia, 46.9% (69 eyes) had moderate hyperopia, and 21.8% (32 eyes) had high hyperopia. In the smaller OZ group, follow-up was 1 month in 79.4% (539 eyes), 3 months in 75.5% (501 eyes), 6 months in 68.5% (465 eyes), and 1 year in 38.3% (260 eyes). The hyperopic population studied was divided into 3 subgroups based on the preoperative spherical equivalents of the manifest refraction: subgroup A, low hyperopia: < or = +2.0 diopters (D); subgroup B, moderate hyperopia: +2.0 to +3.0 D; and subgroup C, high hyperopia: > +3.0 D. The following parameters were measured postoperatively: uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refraction (evolution and distribution), and visual acuity lines gained and lost. RESULTS: The preoperative mean spherical equivalents in the 5.9 mm OZ group were +1.47 +/- 0.41 (SD) (subgroup A); +2.98 +/- 0.41 (subgroup B); and +5.13 +/- 0.61 (subgroup C). In the smaller OZ group, they were +1.31 +/- 0.74, +2.56 +/- 0.28, and +5.28 +/- 0. 69, respectively. At 12 months, the distribution of eyes in the 5.9 mm OZ group with refractions within +/-1.0 D were as follows: subgroup A, 100%; subgroup B, 100%; and subgroup C, 94.2%. In the smaller OZ group, the distributions were 100%, 95.3%, and 71.4%. In the 5.9 mm and the smaller OZ groups, the UCVA was 20/40 or better in 92.0% and 81.8% of eyes, respectively, in subgroup A; 94.6% and 100%, respectively, in subgroup B; and 76.5% and 77.9%, respectively, in subgroup C. The percentage of eyes with 0 +/- 1 line of BCVA 12 months after the procedure was also determined in the 5.9 mm OZ group and compared with the percentages in the smaller OZ group. CONCLUSION: Results of hyperopic LASIK with a 5.9 mm OZ in eyes with low, moderate, and high hyperopia are more stable, predictable, and safe than those in eyes with OZs smaller than 5.9 mm.

Adult↗

PubMed1987

The ribosomal E site at low Mg2+: coordinate inactivation of ribosomal functions at Mg2+ concentrations below 10 mM and its prevention by polyamines.

Under standard conditions (Mg2+/150 mM NH4+) ribosomes can quantitatively participate in tRNA binding at Mg2+ concentrations of 12 to 15 mM. The overall poly(U)-directed Phe incorporation and the extent of tRNA binding to either P, E or A sites decrease in a parallel manner when the Mg2+ concentration is lowered below 10 mM. At 4 mM the inactivation amounts to about 80%. The coordinate inactivation of all three binding sites is accompanied by an increasing impairment of the ability to translocate A-site bound AcPhe-tRNA to the P site. The translocation efficiency is already reduced at 10 mM Mg2+, and is completely blocked at 6-8 mM. The severe inactivation seen at 6 mM Mg2+ vanishes when the polyamines spermine (0.6 mM) and spermidine (0.4 mM) are present in the assay; tRNA binding again becomes quantitative, the total Phe synthesis even exceeds that observed in the absence of polyamines by a factor of 4. In the presence of polyamines and low Mg2+ (3 and 6 mM) two essential features of the allosteric three-site model (Rheinberger and Nierhaus, J. Biol. Chem. 261, 9133 (1986] are demonstrated. 1) Deacylated tRNA is not released from the P site, but moves to the E site during the course of translocation. 2) Occupation of the E site reduces the A site affinity and vice versa (allosteric interactions between E and A sites). The quality of an in vitro system for protein synthesis can be assessed by two criteria. First, the incubation conditions must allow a near quantitative tRNA binding. Secondly, protein synthesis should proceed with near in vivo rate and accuracy. The 3 mM Mg2+/NH4+/polyamine-system seems to be the best compromise at present between these two requirements.

Allosteric Regulation↗

PubMed2002

Clinical and radiographic evaluation of the 5-mm diameter regular-platform Brånemark fixture: 2- to 5-year follow-up.

PURPOSE: The purpose of this study was to report the clinical results obtained with 5-mm diameter regular-platform Brånemark implants after 2 to 5 years of follow-up. A secondary aim was to compare the clinical outcome to that of adjacently placed standard 3.75-mm fixtures in the same patients under the same operative condition and in the same prosthetic construction. MATERIALS AND METHODS: Sixty patients, with a mean age of 54 years, received a total of 97.5-mm diameter regular-platform fixtures. The majority of the implants were placed at molar sites. In 41 of the patients, 53.5-mm diameter implants were placed adjacent to 62 standard 3.75-mm diameter fixtures in the same prosthetic reconstruction. All implants were submerged for an average period of 4 to 6 months. Abutment connection was done according to standard protocol. The prosthetic treatment consisted of freestanding fixed bridges. RESULTS: The cumulative survival rate of the 5-mm diameter implants loaded for a period of 2 to 5 years was 96.9%. Only three implants failed. They were placed in type 4 bone in the posterior maxilla. Bone loss over the first year was 0.70 mm and over a 3-year period 0.81 mm. Implants placed in type 4 bone showed significantly higher bone loss. No difference in the resorption rate could be found between the maxillary and the mandibular implants or between the various implant lengths. There was no significant difference between the bone loss around the 5-mm diameter fixtures and the adjacent 3.75-mm diameter standard fixtures. CONCLUSION: The present study demonstrated a high predictability of 5-mm diameter regular-platform implants when placed in the posterior maxilla and mandible.

Adult↗

PubMed2006

4q loss is potentially an important genetic event in MM tumorigenesis: identification of a tumor suppressor gene regulated by promoter methylation at 4q13.3, platelet factor 4.

In this study, we have elucidated the chromosomal imbalances in the multistep pathogenesis and delineated several critical tumor suppressor gene (TSG) loci in multiple myeloma (MM). By using comparative genomic hybridization, allelotyping, and multicolor interphase fluorescence in situ hybridization, 5 MM cell lines and bone marrow CD138+ plasma cells from 88 Chinese patients with monoclonal gammopathy of undetermined significance (MGUS) and early and advanced stages of MM were investigated. In all MGUS and MM samples, chromosome copy number abnormalities were detected. A higher number of chromosomal imbalances and specific genetic alterations are involved in MGUS to MM transition (-6q, +3p, and +1p) and MM progression (+2p and +9q). In addition to -13q, we first found high frequencies (42% to 46%) of -4q involving high percentages (70% to 74%) of clonal plasma cells in both MGUS and MM, suggesting that inactivation of TSG in this region is also a potentially critical genetic event in MM tumorigenesis. By high-resolution allelotyping, we defined a common deletion region on 4q13.3 and found that a candidate TSG, platelet factor 4, was frequently silenced by promoter hypermethylation in MM (15 of 28) and MM cell lines (5 of 5). These data have opened up a new approach in the molecular targeting therapy and provide novel insights into MM tumorigenesis.

Aged↗

PubMed2004

Results of intracoronary beta-brachytherapy administered by 60 mm transfer device/radiation source train: a subgroup analysis from the RENO registry.

UNLABELLED: To investigate the safety and efficacy of a 60 mm transfer device, delivering 60 mm radiation source train, in the treatment of coronary lesions by b-brachytherapy employing the BetaCath system (Novoste, Norcross, Georgia). METHODS AND RESULTS: As part of the REgistry NOvoste (RENO), the first large-scale registry of intracoronary beta-radiation applied in routine clinical practice, 46 centers registered 1,098 consecutive patients undergoing brachytherapy with the BetaCath system. Of these, 49 patients with 56 lesions were treated with a 60 mm transfer device/radiation source train (TD/RST) in at least 1 vessel, constituting the study population. With 75.4% in-stent restenosis (ISR), 3.6% graft lesions, long lesions (30.9 +/- 14.7 mm) and 19% diabetes, the cohort had a high-risk for recurrence. The in-hospital major adverse cardiac event (MACE) rate was 4.1%. The 6-month follow-up revealed 2.0% death, 4.1% myocardial infarction, 8.2% target vessel revascularization, 12.2% MACE, 82.6% improved angina, 16.7% binary restenosis and 4.1% late thrombosis. The results were comparable to all other patients in the registry treated with standard source lengths of 30 mm and 40 mm, although much longer lesions were treated by the 60 mm device (18.4 +/- 11.3 mm versus 30.9 +/- 14.7 mm; p < 0.0001). In the ISR subgroup (mean lesion length, 32.03 +/- 14.99 mm), the 6-month MACE rate was 12.8%, while the angiographic restenosis rate was 16.0% and the late thrombosis rate was 2.6%. CONCLUSION: Beta-brachytherapy with 60 mm TD/RST was safe, feasible and effective in this broad population of high-risk patients presenting in day-to-day practice. Its efficacy in long-segment ISR, where conventional interventional strategies have poor outcome rates, is particularly noteworthy.

Angioplasty, Balloon, Coronary↗

PubMed2000

Comparison of iceball diameter and temperature distribution achieved with 3-mm accuprobe cryoprobes in porcine and human liver tissue and human colorectal liver metastases in vitro.

We aimed to assess the thermal profile and size of iceballs produced by Accuprobe cryoprobes in fresh porcine and human liver and human colorectal cancer liver metastases in vitro to allow better planning of cryosurgical treatment of liver metastases. Iceballs were produced by a 20-min single freeze cycle using 8-mm cryoprobes in pig liver in a waterbath at 37 degrees C (n = 8) and 3-mm cryoprobes in pig liver (n = 8), human liver (n = 3), and human colorectal cancer liver metastases (n = 8). The iceball diameters and the temperatures at different distances from the cryoprobe were measured. Mean iceball diameters produced by 8-mm cryoprobes in pig liver were 56.3 mm and varied from 38.7 to 39.6 mm for 3-mm cryoprobes in the different tissues used. There was no significant difference in iceball size in the different tissues. The diameter of the zone of -40 degrees C or less was approximately 44 mm using 8-mm cryoprobes in porcine liver and between 27 and 31 mm using 3-mm cryoprobes in the different tissues examined. The results may allow better preoperative planning of the cryosurgical treatment of liver metastases with Accuprobe cryoprobes.

Animals↗

PubMed1986

Highly sensitive enzyme immunoassay for human creatine kinase MM and MB isozymes.

A sensitive enzyme immunoassay system for measurement of MM and MB forms of human creatine kinase (CK) was developed using purified monospecific antibodies to the M subunit and to the B subunit of CK. The CK-MM assay system consisted of polystyrene balls with immobilized F(ab')2 fragments of anti-M and the same antibody Fab' fragments labeled with beta-D-galactosidase from Escherichia coli. The CK-MB was assayed with the polystyrene balls with either antibody (anti-M or anti-B) F(ab')2 fragments and the other antibody (anti-B and anti-M, respectively) Fab' fragments labeled with galactosidase. The assays were highly sensitive and 3 pg of CK-MM and CK-MB were measurable. The CK-MM assay was specific to the M subunit of creatine kinase, and it cross-reacted about 15% with CK-MB, but not with CK-BB. The CK-MB assay did not cross-react with CK-MM nor CK-BB. Therefore, concentrations of CK-MM could be estimated by subtracting the cross-reacting values of CK-MB. Coefficients of variation in within-run and between-run precision studies for serum CK-MM and CK-MB were less than 9%. Serum levels in healthy adults of various ages (16-59 yr old) were ranged from 35.2-132 ng/ml for CK-MM and from 0.40-1.77 ng/ml for CK-MB. There was apparently no statistical significance among the sex- and age-related differences. Concentrations of CK-MM and CK-MB in various human tissues were also determined. The CK-MM was present abundantly in the heart and the tissues composed of striated muscles (skeletal muscle, diaphragm and proximal esophagus). The CK-MB was distributed not only in the heart but also in the striated muscle tissues at a relatively high level.

Adolescent↗

PubMed2006

Leaflet movement of the ATS valve in the aortic position: unique behavior observed in 19-mm valves.

BACKGROUND: Leaflet opening angles of ATS valves in vivo tend to be less than those reported by the manufacturer, and there is a wide variation in opening angles even among valves of the same size. METHODS: Leaflet movement of aortic ATS valves was evaluated by cineradiography in 77 patients. The mean period from valve replacement to cineradiography was 40.2 months, and during that period, the ATS valve was replaced due to prosthetic valve obstruction in 1 of the 77 patients. RESULTS: In 76 patients with a normally functioning ATS valve, the mean opening angle of 19-mm valves (66.3 degrees +/- 2.3 degrees) was significantly less (p < 0.0001) than that of ATS valves 21 mm or larger (72.2 degrees +/- 3.8 degrees in 21-mm, 72.4 degrees +/- 2.8 degrees in 23-mm, and 72.8 degrees +/- 2.9 degrees in 25-mm valves). No significant differences were found in the opening angles of ATS valves 21 mm or larger, and the opening angles exceeded 65 degrees in all 69 patients with valves in this category. In one case of obstruction in a 21-mm valve, the opening angle was 57.5 degrees. The closing angle was 24.9 degrees +/- 1.3 degrees, which corresponded well with the manufacturer's in vitro data. CONCLUSIONS: The opening angle in the 19-mm ATS aortic valve is significantly less than that in valves 21 mm or larger, and an opening angle of less than 65 degrees probably indicates prosthetic valve obstruction in aortic ATS valves sized 21 mm or larger.

Adolescent↗

PubMed2004

Intravascular brachytherapy using 90Sr for saphenous vein grafts having diameters ranging from 2.0-5.0 mm.

PURPOSE: Symptomatic coronary artery disease is routinely treated with angioplasty and stenting. Unfortunately, treatment failure in the form of in-stent restenosis (ISR) occurs relatively frequently. Intravascular brachytherapy (IVBT) is a safe and effective method proven to markedly reduce the rate of ISR in native coronary arteries. The commercially available devices for IVBT are not FDA-approved for treatment of saphenous vein grafts (SVG). This article presents calculated dosimetry for treatment of a wide range of SVG, in addition to further evaluating the dose homogeneity for native coronary arteries. METHODS AND MATERIALS: AAPM Task Group 43 and 60 formalisms permitted dose calculations for a wide range of vessel internal diameters (phi) in both native coronary arteries and SVG. Doses were analytically calculated for the Novoste Beta-Cath 5.0 French (F) treatment devices (30, 40, and 60 mm sourcetrains) when employed for the treatment of native vessels with 2.7 <or= phi <or= 4.0 mm and for SVG with 2.0 <or= phi <or= 5.0 mm. This latter range of phi was segmented into 7 bins to facilitate rapid clinical implementation with minimal errors. Calculations of dose and dose rate for the 3.5 F devices were also performed. Dose inhomogeneity in the form of dose maxima and minima were calculated for the 3.5 and 5.0 F catheters, with the 30, 40, and 60 mm sourcetrains, and for 2.0 <or= phi <or= 5.0 mm. RESULTS: The calculated doses rates for the 30 mm device were in agreement (typically +/- 0.3%) with measured dose rates. Reference dose calculations performed for SVG with 2.0 <or= phi <or= 5.0 mm were in alignment with those used for the more narrow range of native coronary arteries currently approved for IVBT. Errors associated with using a phi binning technique for simplifying clinical implementation did not exceed 15%, and were typically under 9%. The degree of dose inhomogeneity at a depth of 0.5 mm increased as phi increased, catheter size decreased, and sourcetrain length decreased, and was -42% and +101% relative to the prescribed dose for the 40 mm 5.0 F system with phi = 4.0 mm. CONCLUSIONS: Use of 7 phi bins facilitates rapid clinical implementation of IVBT in the typical cardiac catheterization laboratory. While calculation of reference dose for treatment of large vessels is possible with established formalisms, the degree of dose inhomogeneity in light of current clinical results suggests further research is needed.

Brachytherapy↗

PubMed1999

Temperature-controlled radiofrequency catheter ablation with a 10-mm tip electrode creates larger lesions without charring in the porcine heart.

BACKGROUND: Radiofrequency catheter ablation of atrial flutter, atrial fibrillation or ventricular tachycardia may be favoured by large lesions. We compared lesions created in unipolar mode using 10-mm/8 F electrodes with those of 4-mm/7 F catheters. METHODS: Ablations were first performed in porcine hearts in vitro (70 degrees C, 60 s, tangential catheter tip-tissue orientation). Anaesthetized pigs were thereafter ablated with 10- or 4-mm catheters in the right atrial free wall (RAFW), inferior vena cava-tricuspid valve (IVC-TV) isthmus and left ventricle (LV). RESULTS: In vitro, lesion length doubled and lesion volume tripled using the 10-mm catheter. Average power supply was 69 (SD12) (10-mm tip) versus 26 (SD7) W (4-mm tip). In vivo, lesion length increased by 50% and lesion volume fivefold. Charring at the lesion surface or sudden impedance rises were not observed in vivo. Histologically, coagulation necrosis and minor haemorrhages were found. One RAFW lesion (10-mm) showed a dissection approaching the epicardium. Fibrinous platelet clots or overt thromboses covered the endocardial surface in half of all lesions. Three 10-mm electrode isthmus lesions extended to the right descending posterior artery and one LV lesion to the left anterior descending artery, but there was no damage to the arterial walls. Following six ablations with the 10-mm electrode and two with the 4-mm tip, injury to the adjacent lung tissue of 0.5 to 6.0 mm depth was found (p = 0.22). CONCLUSION: RF ablation using 10-mm/8 F electrodes created significantly larger lesions. 10-mm electrodes appeared safe in the porcine IVC-TV isthmus and LV, but not in the RAFW.

Animals↗

PubMed2003

Prospective evaluation of 4-mm diameter endoscopes for esophagoscopy in sedated and unsedated patients.

BACKGROUND: Unsedated esophagoscopy with small-diameter endoscopes is generally well tolerated but of limited sensitivity for the diagnosis of esophageal mucosal disease. This study evaluated the sensitivity of esophagoscopy performed with new 4-mm diameter prototype battery-powered and video endoscopes. Patient tolerance for an unsedated examination with the 4-mm endoscopes was assessed and the performance characteristics of the battery-powered and video 4-mm endoscopes were compared. METHODS: Patients referred for EGD were recruited to undergo an additional examination with a 4-mm endoscope. A prototype 60-cm long, 4-mm diameter battery-powered fiberoptic esophagoscope was used in the first 24 patients and a prototype 60-cm long, 4-mm diameter video esophagoscope in the next 27 patients. Examiners who were unaware of patient history and procedure indications recorded esophageal findings, ease of intubation, optical quality (5-point visual scale), and time for examination of the esophagus and then recorded esophageal findings after the standard EGD. RESULTS: The sensitivity, specificity, and accuracy for identification of Barrett's esophagus was 100%; overall sensitivity, accuracy, and specificity for detecting esophageal lesions were, respectively, 91%, 98%, and 99%. Patient tolerance (assessed by symptom scores for choking, pain, and discomfort) and acceptability of unsedated esophagoscopy with the 4-mm diameter instruments were significantly better than in a historical group of patients examined with a 3-mm diameter endoscope. The optical quality of video endoscope was rated as superior to that of battery-powered endoscope, and esophageal examination was performed significantly quicker with the video versus the battery-powered endoscope (68 vs. 137 seconds; p = 0.001). CONCLUSIONS: Unsedated esophagoscopy with 4-mm diameter endoscopes may be an alternative to EGD for screening for Barrett's esophagus. Given the current state of endoscopic technology, a minimum diameter of 4 mm is required for satisfactory esophageal imaging.

Barrett Esophagus↗

PubMed2000

An efficient method of measuring the 4 mm helmet output factor for the Gamma knife.

It is essential to have accurate measurements of the 4 mm helmet output factor in the treatment of trigeminal neuralgia patients using the Gamma Knife. Because of the small collimator size and the sharp dose gradient at the beam focus, this measurement is generally tedious and difficult. We have developed an efficient method of measuring the 4 mm helmet output factor using regular radiographic films. The helmet output factor was measured by exposing a single Kodak XV film in the standard Leksell spherical phantom using the 18 mm helmet with 30-40 of its plug collimators replaced by the 4 mm plug collimators. The 4 mm helmet output factor was measured to be 0.876 +/- 0.009. This is in excellent agreement with our EGS4 Monte Carlo simulated value of 0.876 +/- 0.005. This helmet output factor value also agrees with more tedious TLD, diode and radiochromic film measurements that were each obtained using two separate measurements with the 18 mm helmet and the 4 mm helmet respectively. The 4 mm helmet output factor measured by the diode was 0.884 +/- 0.016, and the TLD measurement was 0.890 +/- 0.020. The radiochromic film measured value was 0.870 +/- 0.018. Because a single-exposure measurement was performed instead of a double exposure measurement, most of the systematic errors that appeared in the double-exposure measurements due to experimental setup variations were cancelled out. Consequently, the 4 mm helmet output factor is more precisely determined by the single-exposure approach. Therefore, routine measurement and quality assurance of the 4 mm helmet output factor of the Gamma Knife could be efficiently carried out using the proposed single-exposure technique.

Film Dosimetry↗

PubMed1999

Laparoscopic genitourinary surgery utilizing 20 mm Hg intra-abdominal pressure.

Traditional practice has dictated that intra-abdominal pressure during laparoscopy be kept at or below 15 mm Hg to minimize the risk of cardiovascular and pulmonary complications. This study was undertaken to determine if maintaining an intra-abdominal pressure of 20 mm Hg could be utilized safely during genitourinary laparoscopy. We reviewed the intraoperative records of 76 consecutive patients undergoing various endoscopic urologic procedures at an intra-abdominal pressure of 20 mm Hg to assess physiologic changes and complications. The records were examined for operating time, minute ventilation (MV), end-tidal CO2 (ETCO2), and peak inspiratory pressure (PIP), which were compared with the preinsufflation values. Also, in the first 39 patients, initial insufflation volumes were recorded at 15 mm Hg and then again when pressure was raised to 20 mm Hg. The mean operating time was 186 +/- 90 min. There was an average 22% increase in the sufflated volume when the pressure was elevated from 15 to 20 mm Hg. To maintain a suitable ETCO2, the anesthesiologist needed to increase the MV an average of 2.9 +/- 2.0 L/min. Increases in ETCO2 (average 4.5 +/- 4.6 mm Hg) and PIP (6.9 +/- 3.6 mm Hg) were noted. In two cases, the intra-abdominal pressure had to be decreased from 20 to 15 mm Hg because of inability to maintain an acceptable ETCO2. Subcutaneous emphysema was noted in three patients, which resolved spontaneously within 24 hr. In one patient, asymptomatic pneumomediastinum was noted after a 6-hr procedure. Intra-abdominal insufflation can be safely maintained at 20 mm Hg in most patients. This higher pressure improves maintenance of the pneumoperitoneum.

Adult↗