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Biomedical subjects

C C Wang

Publications and source records attributed to C C Wang.

At least 307 records · Page 17Linked to original sources
PubMed1996

Left ventricular fibromuscular band is not a specific substrate for idiopathic left ventricular tachycardia.

BACKGROUND: A fibromuscular band has been detected in patients with idiopathic left ventricular tachycardia, and this band has been suggested to be the anatomic substrate for the arrhythmia. Whether the fibromuscular band is a specific substrate for the tachycardia was systematically evaluated in a large group of consecutive patients with and without idiopathic left ventricular tachycardia. METHODS AND RESULTS: Conventional transthoracic two-dimensional echocardiography and multiplane transesophageal echocardiography were performed in 18 patients with idiopathic left ventricular tachycardia that was responsive to calcium blockers (group 1, tachycardia patients) and 40 patients with paroxysmal supraventricular tachycardia (group 2, control patients). There were 17 men and 1 woman, with a mean age of 29 +/- 11 years, in group 1 patients, and 21 men and 19 women, with a mean age of 42 +/- 12 years, in group 2 patients. The QRS morphology during tachycardia in group 1 patients displayed a pattern of right bundle-branch block with superior axis in 15 patients, indeterminate axis in 2 patients, and inferior axis in 1 patient. Radiofrequency ablation successfully eliminated the tachycardia in all 18 patients; the successful ablation site was located at the inferior apical septum in 11 patients, at the midseptum in 6 patients, and at the anterior lateral wall in 1 patient. Transthoracic echocardiography detected the fibromuscular band in 11 of the 18 patients, whereas multiplane transesophageal echocardiography detected the band in 17 of 18 patients. The fibromuscular band extended from the interventricular septum to the apex of the left ventricle. In group 2 patients, transthoracic echocardiography detected the fibromuscular band in 22 and multiplane transesophageal echocardiography detected the band in 35 of the 40 patients. The presence of a fibromuscular band in these two groups of patients was not statistically different. CONCLUSIONS: The presence of a left ventricular fibromuscular band is not a specific anatomic substrate for idiopathic left ventricular tachycardia.

Adult↗
PubMed1996

Thymidine kinase as a selectable marker for studying the biogenesis of glycosomes in Trypanosoma brucei.

The import of proteins into the glycosome of T. brucei has been studied as a potential target for antitrypanosomal chemotherapy. We have previously reported on the C-terminal tripeptides, such as SKL and its analogs, which function as targeting signals in the import of proteins into glycosomes. Recently, we tested the herpes simplex virus thymidine kinase gene (tk) as both a potential positive and a negative selectable marker in T. brucei for isolating glycosome-deficient T. brucei mutants in the procyclic form and complementation studies to identify genes involved in glycosomal biogenesis. The transforming vectors that we have constructed contained the hygromycin phosphotransferase gene (hyg) coupled either to the tk gene (ptk) or to the gene encoding the thymidine kinase fused with the glycosomal targeting signal (ptk-SKL) at the C-terminus. Individual constructs were introduced into the T. brucei 427 procyclic cells by electroporation, and the transformants were selected under hygromycin B (50 micrograms/ml) and cloned. The thymidine kinase activity in the crude extracts of transformants was determined. Differential digitonin treatment of the transformants indicated that the tk-SKL protein was apparently localized to the glycosomal fraction, as expected, whereas the tk protein was found in the soluble fraction. [methyl-3H]Thymidine was incorporated into the nucleic acids of the transformant 427/ptk to a level twice as high as that incorporated into 427/ptk-SKL and the wild type. In the presence of 100 microM ganciclovir, the growth of 427/ptk was totally inhibited, whereas growth of 427/ptk-SKL and the wild type was unaffected. When 150 microM trimethoprim was added to the culture medium, growth of 427/ptk-SKL and the wild type was completely arrested while that of 427/ptk remained normal. We have thus established the methodology for both positive and negative selection of potential glycosome-deficient mutants of T. brucei 427/ptk-SKL.

Amino Acid Sequence↗
PubMed1996

Techniques for intrasplenic hepatocyte transplantation in the large animal model.

BACKGROUND: The preferred therapy for acute and chronic liver insufficiency and severe heritable disorders of liver metabolism is whole-organ transplantation. However, due to the shortage of organ donors and high cost, alternative therapeutic approaches have been proposed, including transplantation of normal allogeneic hepatocytes. Recently, it has been reported that many hepatocytes transplanted into the spleen migrated to the liver. We therefore carried out a series of large-animal experiments to reexamine the intrasplenic route and to develop a method for large-scale hepatocellular transplantation in pigs. METHODS: Allogeneic porcine hepatocytes were transplanted using the following routes: (1) retrograde injection of cells via the splenic vein, (2) intraarterial injection of cells, (3) direct intrasplenic injection of cells after laparotomy, (4) percutaneous intrasplenic injection of cells under laparoscopic control, (5) laparoscopic intrasplenic injection of cells. The number of cells injected varied from 2 x 10(9) to 10 x 10(9) cells. RESULTS: Of all the methods tested, only direct intrasplenic injection of 2 bln of cells was found to be compatible with survival. However, even with this "small" number of cells (2% original liver mass), there was a significant risk of spleen infarction, perisplenic adhesion formation, and portal vein thrombosis. The laparoscopic approach was found to be reliable, simple, and safe. CONCLUSION: Even though the spleen is considered by many authors the optimal site for hepatocellular transplantation, transplantation of cells in a number needed to support the failing liver may be associated with significant complications, morbidity, and mortality.

Animals↗
PubMed1996

Effects of aphidicolin and hydroxyurea on the cell cycle and differentiation of Trypanosoma brucei bloodstream forms.

The effects of aphidicolin (APH) and hydroxyurea (HU) on the cell cycle and differentiation of Trypanosoma brucei bloodstream forms were studied. APH (0.1 microgram ml-1) inhibited cell division, but did not inhibit DNA synthesis. Most of the cells were arrested in the G2 phase of the cell cycle, with each cell containing two kinetoplasts, but only one nucleus. Recovery of the arrested cells showed a 24-h lag period compared to controls. Higher concentrations of APH (1 and 10 micrograms ml-1) were required to inhibit DNA synthesis, but the cells failed to resume growth after removal of the drug. Incubation of cells with HU (7.5 micrograms ml-1) did not inhibit DNA synthesis, but arrested cells after duplicating both the kinetoplast and the nucleus. Recovery from drug arrest also showed a 24-h lag period. We therefore conclude that neither APH nor HU arrests T. brucei at the G1/S phase boundary as anticipated. The mechanisms of cell cycle arrest by APH and HU are not through inhibition of DNA synthesis, but rather through unidentified pathways, leading to growth arrest prior to nuclear division and cytokinesis respectively. Since the arrested cells do not resume normal development immediately following drug removal, APH and HU should be regarded as unsuitable agents for synchronizing T. brucei bloodstream forms. T. brucei bloodstream forms arrested with either APH or HU differentiated normally into procyclic forms in vitro, indicating that a cycle of cell division is not required for initiation of differentiation, and that the process can be initiated and completed when cells are arrested at the G2/M and M/G1 phase boundaries.

Animals↗
PubMed1996

Catheter-induced atrioventricular nodal block during radiofrequency ablation.

This study examined the incidence and significance of catheter-induced atrioventricular nodal block (AVNB) during a radiofrequency ablation procedure that uses stiff large-tip steerable ablation catheters. AVNB was noted in 10 (1.6%) of 613 consecutive patients undergoing radiofrequency ablation therapy for atrioventricular nodal (AVN) reentrant tachycardia (592 patients) or atrioventricular reentry tachycardia incorporating a midseptal accessory pathway (21 patients). Of these 10 patients, 9 underwent AVN modification for AVN reentrant tachycardia and 1 for ablation of a midseptal accessory pathway. One patient had two episodes of AVNB during two sessions undertaken because of recurrence of tachycardia. No patient had a preexisting conduction defect before the study. In all 10 patients, AVNB was transient, and it lasted for a mean of 9.1 +/- 19 minutes. It occurred during positioning of the ablation catheter in the junctional area before (8 patients) or after (2 patients) the start of radiofrequency current applications. Complete AVNB was noted on six occasions, second-degree AVNB on four occasions, and first-degree AVNB on one occasion. All blocks were associated with narrow QRS ventricular beats and with a site of block proximal to the His bundle. The mean ventricular heart rate during AVNB was 60 +/- 23 beats/min. Two patients had transient asystole, with one having loss of consciousness. No patient required special treatment for heart block. One-to-one conduction resumed after repositioning of the catheters, and the subsequent ablation procedure was successfully completed in 8 of the 10 patients. During a follow-up of 20 +/- 12 months, none of the patients had severe dizziness or syncope, and none required implantation of a permanent pacemaker. In conclusion, transient AVNB due to mechanical injury occurs during positioning of a stiff large-tip steerable ablation catheter in the junctional area. Delivery of radiofrequency current to the site that provokes catheter-induced AVNB should be avoided.

Adolescent↗
PubMed1996

Radiofrequency ablation therapy of the posteroseptal accessory pathway.

Among 652 patients with Wolff-Parkinson-White syndrome who underwent radiofrequency ablation in this laboratory, 139 (21%) were found to have a total of 146 posteroseptal accessory pathways. Ablation was conducted by the regular transvenous or transaortic approach; ablation from cardiac venous structures was used only if regular approaches were unsuccessful. Of the 146 posteroseptal accessory pathways, 94 were successfully ablated from the left posteroseptal region and 45 from the right posteroseptal region. In 3, successful ablation of the accessory pathway required delivery of the current to the proximal coronary sinus, and in 1 it required delivery of the current to both the atrial and ventricular aspects of the tricuspid valve at the right posteroseptum. Thus, the accessory pathway was successfully ablated in 143 (98%) of 146 instances or in 136 (98%) patients. In 3 patients, ablation was unsuccessful despite delivery of current to the left posteroseptum, the right posteroseptum, the proximal coronary sinus, and the middle cardiac vein. Seventy-seven (57%) patients with an initial success, including 9 patients with resumed preexcitation or recurrence of paipitations, underwent a follow-up electro-physiologic study 90 +/- 72 days after ablation. Of these 9 patients, the initial successful ablation site was the right posteroseptum in 7 and the left posteroseptum in 2. The accessory pathways were ablated successfully by subsequent trials in 8 patients, whereas in 1 the accessory pathway was severely damaged. Thus radiofrequency ablation of posteroseptal accessory pathways can be achieved by the regular transvenous or transaortic approach; delivery of current to the coronary sinus or middle cardiac vein is unnecessary in most patients.

Adult↗
PubMed1996

Purification and characterization of proteasomes from Trypanosoma brucei.

Proteasomes are multisubunit proteases that exist universally among eukaryotes. They have multiple proteolytic activities, and are believed to have important roles in regulating cell cycle, selective intracellular proteolysis, and antigen presentation. To determine the possible role that proteasomes may play in controlling the life cycle of African trypanosomes, we have isolated proteasomes from the bloodstream and the insect (procyclic) forms of Trypanosoma brucei by DEAE-cellulose chromatography and glycerol gradient fractionation in the presence of ATP. No 26 S proteasome homologs was identified in T. brucei under these experimental conditions. The proteasomes isolated from these two forms of T. brucei are very similar to the rat blood cell 20 S proteasome in their general appearance under the electron microscope. The profile of trypanosome proteasome subunits in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) has eight visible protein bands with molecular weights ranging from 23 to 34 kDa, and cross-reacted very poorly with the anti-human 20 S proteasome antibodies on immunoblots. Two-dimensional gel electrophoresis of the parasite proteasomes shows a similar number of major subunits with pI's ranging from 4.5 to 7. Using a variety of fluorogenic peptides as substrates, the trypanosome proteasomes exhibited unusually high trypsin-like, but somewhat lower chymotrypsin-like activities, as compared to the rat 20 S proteasome. These proteolytic activities were, however, insensitive to phenylmethylsulfonyl fluoride (PMSF), tosyl-phenylalanine chloromethylketone (TPCK), tosyl-lysine chloromethylketone (TLCK) and trans-epoxy succinyl-L-leucylamido-(4 guanidino) butane (E-64), but the trypsin-like activity of trypanosome proteasomes was inhibited by leupeptin, an aldehyde known to inhibit the trypsin-like activity of mammalian proteasomes, thus ruling out possible contamination by other serine or cysteine proteases. Some quantitative differences in the substrate specificities between the proteasomes from bloodstream and procyclic forms were indicated, which may play a role in determining the differential protein turnovers at two different stages of development of T. brucei.

Amino Acid Sequence↗
PubMed1996

Cloning, expression and characterization of an unusual guanine phosphoribosyltransferase from Giardia lamblia.

Giardia lamblia is one of the most ancient eukaryotes identified to date. It lacks de novo purine biosynthesis and is thought to rely solely on the functions of two salvage enzymes, adenine and guanine phosphoribosyltransferases (APRTase and GPRTase). We have cloned the gene encoding the G. lamblia GPRTase by complementation of the E. coli strain Sø609 (delta gpt-pro-lac, thi, hpt, pup, purH,J, strA) with a genomic library consisting of Sau3AI-digested G. lamblia DNA inserted into the Bluescript vector. Transformed Sø609 colonies grew on minimal medium supplemented with guanine at a frequency of 3.3 x 10(-5) ampicillin-resistant colonies, but were unable to salvage hypoxanthine or xanthine, as predicted from previous studies of the native G. lamblia GPRTase. The sequence analysis of cloned DNA fragments reveals an open reading frame of 690 bp, encoding a protein of 26.3 kDa with an estimated pI of 6.83, in agreement with the reported subunit molecular weight of the native G. lamblia GPRTase. The deduced protein has less than 20% sequence identity to the human and other known HGPRTases, and features several significant changes in the primary sequence of the putative active sites of the enzyme, which may reflect the stringent substrate specificity of GPRTase. The recombinant GPRTase was expressed in E. coli and purified to > 95% homogeneity. Kinetic studies of the recombinant enzyme showed an apparent K(m) of 74 microM for guanine. Hypoxanthine as an alternate purine substrate was used only when present in millimolar amounts, and xanthine was not utilized at all. This Giardia enzyme is thus a highly unique purine PRTase without a known parallel in any other living organisms.

Amino Acid Sequence↗
PubMed1996

Procyclic Trypanosoma brucei cell lines deficient in ornithine decarboxylase activity.

Ornithine decarboxylase (ODC) is a rate limiting enzyme in the biosynthesis of polyamines. We report here the construction of ODC gene deficient Trypanosoma brucei brucei cell lines by homologous recombination and disruption of the two alleles of the ODC gene. With our first stable transfection vector, we replaced the 2.8 kb SacII ODC gene-containing fragment with a hygromycin-B-phosphotransferase gene (hph) cassette transcribed under the control of the endogenous promoter. For the second ODC allele knock-out, we stably transfected similar constructs that contained either the phleomycin or G418 resistance gene cassette, and included 1 mM putrescine in the media. These experiments resulted in two separate ODC- lines: one hygromycin and phleomycin resistant, the other hygromycin and G418 resistant. The two ODC gene knockout lines were verified by Southern and Northern hybridization, and confirmed by Western blot and enzymatic activity assay. There is no ODC expression in the two ODC- lines and the ODC messages in the single ODC gene knockouts were only half of that of the wild type. When grown in the presence of putrescine, the ODC- lines showed little difference, morphologically, from wild type trypanosomes. The growth rate of these lines varied greatly, depending on the concentration of the putrescine. Interestingly, when putrescine was completely withdrawn from the media, the ODC- trypanosomes soon reached a plateau phase and some cells remained viable for 7-8 weeks. The starved cells could be rescued by the addition of putrescine or introducing back the ODC gene. Cell cycle analysis suggested that putrescine is required for G1-S transition in the procyclic form T. brucei.

Alleles↗
PubMed1996

Complications associated with therapeutic neck radiation.

PURPOSE: This retrospective study of patients who underwent neck radiation as part of their treatment for squamous cell carcinoma of the oral cavity sought to identify and quantify the morbidity associated with this treatment. PATIENTS AND METHODS: Thirty-five patients who received neck radiation between 1985 and 1992 were randomly recalled for examination. All patients had been treated in a standardized fashion by the Department of Radiation Oncology. The long-term effects of neck radiation on skin changes, thyroid function, and neck range of motion, of atherosclerotic carotid artery disease, xerostomia, and glottic structures were measured. RESULTS: Fifty-seven percent of patients demonstrated grade 1 skin changes. No severe changes were noted, and no development of secondary neoplasia was observed. There was no linear trend observed between radiation dose and skin changes. Hypothyroidism developed in 14.3% of patients within 3.5 years posttreatment. Logistic regression demonstrated a significant association between hypothyroidism and radiation dose. Limitation of neck mobility was the most significant complication with deficits demonstrated in all ranges of motion. Carotid bruits were documented in 14.3% of patients, with a significant association between the higher neck dosage in N+ cases. Xerostomia was found in 68% of patients. There was persistent glottic erythema in 11.4% of patients. CONCLUSIONS: The results of this study indicate that there are persistent complications after neck radiation, which include limitation of neck movement, diminished thyroid function, accelerated carotid artery narrowing, and skin and salivary changes.

Carcinoma, Squamous Cell↗
PubMed1996

Amnioinfusion for the prevention of meconium aspiration during labour.

The aim of this observational study is to review the outcome of prophylactic intrapartum amnioinfusion (AI) in pregnancies complicated by moderate to thick meconium-stained liquor (MSL). The labour and neonatal outcome of all 298 AIs performed over a 3-year period were compared to a matched-control group of patients whose labour was complicated by moderate or thick MSL but without AI. The incidence of moderate or thick meconium below the vocal cords of the neonate were significantly lower in the AI group (6.4% and 3.4%) compared with the control group (15.4% and 6.7%). The incidence of meconium aspiration syndrome in the AI group was half (1.7%) that of the control group (3.7%), although the difference did not reach statistical significance. There was a significant higher incidence of cardiotocographic abnormalities in the AI group (30.5% versus 14.7%), with higher incidences of Caesarean section and operative vaginal deliveries. The reduction in the incidence and thickness of meconium after AI was not accompanied by any statistically significant reduction in adverse fetal outcomes such as low Apgar scores, cord pH values, admissions to and duration of admission to the neonatal unit, or the incidence of meconium-aspiration syndrome.

Adult↗
PubMed1996

Amplification, expression, and packaging of a foreign gene by giardiavirus in Giardia lamblia.

Giardia lamblia is an intestinal protozoan parasite and one of the earliest eukaryotic divergents. The trophozoite multiplies via asexual binary fission and lacks all natural means of lateral gene transfer. A system is developed here for long-term expression of a foreign gene in this organism by exploiting recombinant virions derived from the giardiavirus (GLV), a double-stranded RNA virus that infects many Giardia isolates. An in vitro transcript of the cloned GLV cDNA, comprising the firefly luciferase-encoding region flanked by 5' and 3' fragments of GLV positive-strand RNA, was electroporated into GLV-infected trophozoites. Luciferase activity in electroporated cells peaked on day 2 at levels 6 orders of magnitude above background. Expression of this foreign gene remained at 80% of its peak level after 30 days in the absence of selective pressure. The chimeric RNA was replicated as double-stranded RNA and packaged into virus-like particles. The recombinant virions were partially purified from the wild-type helper virus by CsCl equilibrium density-gradient centrifugation and used to superinfect Giardia trophozoites. At multiplicities of infection of 100 or higher, these chimeric virions were able to initiate new rounds of expression of luciferase activity in the superinfected cells. Thus, the engineered virion can be successfully used to introduce and efficiently express a heterologous gene in this eukaryotic microorganism.

Animals↗
PubMed1996

TNF alpha gene and protein expression in alveolar macrophages in acute and chronic hyperoxia-induced lung injury.

Alveolar-capillary membrane remodeling, including microvessel wall thickening and interstitial fibrosis, is a well-known sequela of cell proliferation in the hyperoxia-injured lung. The array of growth molecules released locally that potentially mediate this response, and their cell(s) of origin, are currently being defined. To elucidate the role of tumor necrosis factor alpha (TNF alpha), an effector molecule of cell injury and proliferation, and the role of the alveolar macrophage (AM) as its source during the acute (1 to 24 h) and chronic stages (3 to 28 days) of hyperoxia-induced injury, we have analyzed gene and protein expression in cells recovered from rat lung by bronchoalveolar lavage. In the hyperoxic lung, cell number was similar to that in normal lung (1 x 10(6)) except on day 7, when it was higher (5 x 10(6)). Virtually all cells recovered from the normal and hyperoxic lung were AMs, with the exception that on days 3 and 7 of hyperoxia these cells represented 69% and 55% of the population, respectively, and polymorphonuclear leukocytes and lymphocytes the remainder. Probe specificity was confirmed by detection of TNF alpha RNA (1.6 kb) from lung cells recovered after lipopolysaccharide (LPS) treatment (positive control) and from the hyperoxic lung (at day 3), with an extremely low level of constitutive expression detected in cells from normal lung. In cytospin preparations, TNF alpha mRNA transcripts were detected in few AMs recovered from normal lung and in most AMs after LPS treatment. In the hyperoxic lung, a signal was detected at 3 h, when approximately 25% of the population was positive. The number of hybridizing cells then increased, being highest on day 7 (day 1 approximately 30%, day 3 approximately 58%, day 7 approximately 90%, day 28 approximately 65%). No expression of TNF alpha protein was detected in AMs from normal lung; positive cells were detected in the hyperoxic lung from day 1 and thereafter. We conclude from upregulation of the TNF alpha gene in a significant number of cells, and from the increase in the number expressing biologically active protein, that AMs are an important source of this molecule both in the acute and chronic stages of hyperoxic lung injury. It is anticipated that an increased understanding of the cellular sources of mediators effecting vascular and alveolar wall remodeling in vivo will contribute to the development of strategies to inhibit the response.

Animals↗
PubMed1996

Mechanical properties of single pellets containing acrylic polymers.

Three aqueous-based acrylic latex dispersions, Eudragit L 30 D, NE 30 D, and RS 30 D, were incorporated as granulating binders into a powder blend of microcrystalline cellulose and anhydrous lactose by wet massing. Spheronized pellets were prepared by extrusion-spheronization and the mechanical properties of single pellets, including the tensile strength at break and the Young's modulus were determined from the stress-strain profiles using a Chatillon TCD-200 tension/compression digital test gauge. The influence of particle size and plasticizer on the mechanical properties of pellets containing Eudragit RS 30 D was investigated. All bead formulations deformed by brittle fracture under a diametral compression force. The mechanical strength was found to be influenced by the adhesive strength between the polymers and the powder particles instead of the cohesive strength of each polymer. The Young's modulus and the tensile strength were also significantly influenced by the type and concentration of polymer, the presence of plasticizer, and the particle size of the beads. The results were related to the properties of the polymers and the fracture mechanisms of the beads. Furthermore, the polymer type and the incorporation of plasticizer influenced the susceptibility of the moistened extruded granules to the shearing forces during the spheronization process, which influenced the surface morphological properties of the pellets.

Acrylates↗
PubMed1996

[The bonding mechanisms of base metals for metal-ceramic crown microstructure analysis of bonding agent and gold bond between porcelain and base metals].

The use of base metal alloys for porcelain fused to a metal crown and bridges has increased recently because of lower price, high hardness, high tensile strength and high elastic modulus. The addition of beryllium to base metal alloys increased fluidity and improved casting fitness. Beryllium also controlled surface oxidation and bonding strength. The bonding agent and gold bonding agent also affected the bonding strength between porcelain and metal alloys. Four commercially available ceramic base alloys were studied (two alloys contained beryllium element, another two did not). The purpose of this investigation was to study the microstructure between porcelain matrix, bonding agent and alloy matrix interfaces. A scanning electron micro-probe analyzer and energy dispersive X-ray spectroscopy (EDXS) were used to study the distribution of elements (Ni, Cr, Mo, Cu, O, Si, Sn, Al) in four base alloys. The following results were obtained: 1. The thickness of the oxidized layer of Rexillium III alloy and Unitbond alloy (contained beryllium) was thinner than Unibond alloy and Wiron 88 alloy (no beryllium). 2. The thickness of the oxidized layer of alloys in air (10 minutes and 30 minutes) was thinner in Unitbond (2.45 microns and 3.80 microns) and thicker in Wiron 88 (4.39 microns and 5.96 microns). 3. The thickness of the oxidized layer occurring for a duration of ten minutes (in vaccum) showed that the Rexillium III alloy was the thinnest (1.93 microns), and Wiron 88 alloy was the thickest (2.30 microns). But in thirty minutes (vacuum), Unitbond alloy was the thinnest (3.37 microns), and Wiron 88 alloy was the thickest (5.51 microns). 4. The intensity of Cr elements was increased obviously near the interface between Unitbond alloy, Wiron 88 alloy (no beryllium) and oxidized layer, but the intensity of Ni and Mo elements was slightly increased. The intensity of Cr element was not increased markedly between Rexillium III alloy, Unitbond alloy (beryllium) and oxidized layer. 5. A white-grayish oxidized layer appeared at the metal-ceramic interfaces but the thickness of oxidized layer was not obviously different. 6. The use of bonding agent at metal-ceramic interface leads to the deposition of many Sn elements at about 40 microns range within the porcelain surface. 7. Second interaction phases at the porcelain layer appeared when gold bonding agent was used, and a 50-100 microns microleakage occurred at the metal-ceramic interface.

Dental Bonding↗
PubMed1996

Allogeneic bone marrow transplantation for fourteen patients with severe aplastic anemia.

BACKGROUND: Bone marrow transplantation (BMT) is the best curative approach for younger patients with severe aplastic anemia (SAA). Major obstacles to success of allogeneic BMT include graft-versus-host disease (GVHD), graft rejection and treatment related toxicities. Experience with 14 SAA patients who received BMT is reported here. METHODS: From December 1986 to May 1995, 14 patients with SAA were treated with BMT; 13 were allogeneic, and 1 was syngeneic. There were nine males and five females whose average age was 24.7 years (range 15-36 years). The median pretransplant disease duration was 93 days (range 7-610 days). Five patients were nontransfused before BMT. The pretransplant conditioning regimen consisted of 200 mg/kg cyclophosphamide (CY) intravenously, divided over four consecutive days, followed by 300 cGy total-body irradiation (TBI) on the day before BMT. Two untransfused, one transfused patient and one syngeneic transplant received CY only as preconditioning. For GVHD prophylaxis, the 13 patients were given a combination of cyclosporine and a short course of methotrexate. RESULTS: Of the 14 patients, 11 were still alive 10 to 90 months later, with functional engraftment; the median survival of 39 months. There were three deaths including one with primary graft failure with intracranial hemorrhage, and two with delayed graft rejection and sepsis. The patient who received syngeneic BMT developed late graft failure six months post-transplant, but was successfully treated with a second BMT. Acute GVHD occurred among 5 of the 13 engrafted patients, only one of whom was Grade III clinically. Chronic GVHD was observed in 2 out of 10 evaluable patients. CONCLUSIONS: The combination of CY and TBI is an effective, well-tolerated conditioning regimen for BMT in patients with SAA. The acute GVHD rate was low in our patients receiving cyclosporine. BMT is the treatment-of-choice for patients under the age of 40 with SAA, for those with human leucocyte antigen (HLA)-identical siblings or an identical twin and particularly for those patients who have not received transfusion.

Adolescent↗