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Biomedical subjects

F Lin

Publications and source records attributed to F Lin.

At least 163 records · Page 9Linked to original sources
PubMed1994

Symptomatic double-channel pylorus. Successful treatment with a biliary sphincterotome.

A patient with a previous vagotomy and pyloroplasty was evaluated for symptoms of gastric outlet obstruction. Endoscopy revealed a thick, fibrous bridge that created a dual-channel pylorus. Symptomatic improvement was not achieved with balloon dilatation. Surgery was avoided by dividing the tissue bridge endoscopically with a sphincterotome. Since reestablishing a normal pyloric aperture, the patient's symptoms have been alleviated. This is the first description of this minimally invasive technique in the management of a symptomatic double-channel pylorus.

Endoscopy, Digestive System↗
PubMed1994

Cloning and sequencing of an endo-beta-1,4-glucanase gene mcenA from Micromonospora cellulolyticum 86W-16.

Endo-beta-1,4-glucanase gene mcenA of Micromonospora cellulolyticum 86W-16 was cloned, and the nucleotide sequence was determined. An open reading frame (ORF) of 1374 bases, coding for a peptide (McenA) of 457 amino acids and 46,742 Da, was found. It is preceded by a Gram-positive type of ribosome-binding site and followed by an imperfect inverted repeat. A putative signal peptide containing 23 amino acids is at the N-terminus and a linker region possessing 37 amino acids is in the midpart of McenA. The N-half of McenA functions as the catalytic domain and the C-half might serve as a cellulose-binding domain (CBD). Deletion of the latter did not decrease the CMCase activity of McenA. Significant similarity (70%) was found between the amino acid sequences of McenA and MbcelA, an endoglucanase from Microbispora bispora.

Amino Acid Sequence↗
PubMed1994

Detection of proteins and sialoglycoproteins in polyacrylamide gels using eosin Y stain.

An eosin Y staining technique that permits detection of various proteins, including membrane sialoglycoproteins, in polyacrylamide gels is described. The sensitivity of the eosin Y staining method is comparable to silver staining. In addition, there is an added advantage of the antigenicity of the stained proteins being retained in a Western blot. Details of the procedure to obtain optimal staining results are described.

Antigens↗
PubMed1994

Regulation and localization of colony-stimulating factor-1 mRNA in cultured rat dental follicle cells.

Cultured dental follicle cells from rat mandibular molars transcribe colony-stimulating factor-1 (CSF-1) mRNA as determined by reverse-transcription polymerase chain reaction. In turn, the CSF-1 mRNA appears to be translated, as seen by immunoperoxidase staining. Interleukin 1 alpha (IL-1 alpha) stimulates increased transcription of the CSF-1 gene in a concentration- and time-dependent manner. Moreover, CSF-1 itself has an autocrine effect on transcription of the CSF-1 gene. Because others have shown that in vivo injection of CSF-1 accelerates tooth eruption and because the dental follicle is required for eruption to occur, this study demonstrates the possible relation between CSF-1 and the follicle; namely, the source of CSF-1 for tooth eruption might be the dental follicle. In turn, regulation of gene expression for CSF-1 by IL-1 alpha and CSF-1 may play a part in signalling the onset of tooth eruption.

Animals↗
PubMed1994

Trisomy 11 and other nonrandom trisomies in congenital fibrosarcoma.

Chromosome studies in a 7-week-old female infant with an intraabdominal malignant fibrosarcoma showed a hyperdiploid karyotype of 50,XX, +der(6)del(6)(p23)add(6)(q11), +8, +10, +11,add(12)(p13). Trisomy 11 appears to be a nonrandom primary cytogenetic abnormality in the congenital or infantile form of this mesenchymal tumor and is also a nonrandom gain in congenital mesoblastic nephroma. A possible developmental link between these two mesenchymal tumors, mediated by a gene or genes on chromosome 11 is postulated.

Chromosomes, Human, Pair 11↗
PubMed1994

Bleaching of membrane-bound merocyanine 540 in conjunction with free radical-mediated lipid peroxidation.

The lipophilic dye merocyanine 540 (MC540) can photosensitize potentially lethal cell membrane damage as well as its own degradation (bleaching). Photobleaching in a test membrane, the human erythrocyte ghost has been examined. White light irradiation of MC540-sensitized ghosts resulted in lipid hydroperoxide (LOOH) formation, low-level thiobarbituric acid (TBA) reactivity, and dye bleaching (A568 decay). When the reaction was carried out in the presence of ascorbate (AH-), and added Fe3+, there was a large enhancement of TBA reactivity (indicative of free radical-mediated lipid peroxidation) and concomitant increase in the rate of photobleaching. Rapid bleaching also occurred when MC540 was incubated in the dark with ghosts that had been photoperoxidized with another dye (a phthalocyanine) and then exposed to AH-. The extent of bleaching in this system was found to be proportional to the starting level of LOOH. Like the wave of free radical lipid peroxidation that accompanied it, dye bleaching in AH(-)-treated, preperoxidized ghosts was stimulated by supplemental Fe3+, inhibited by desferrioxamine or butylated hydroxytoluene (BHT), but unaffected by catalase or superoxide dismutase. From this and related evidence, we deduce that: (1) in the absence of Fe3+/AH-, photoperoxidation and photobleaching occur independently and are nonradical, singlet oxygen-mediated processes; and (2) in the presence of Fe3+/AH-, 1-electron reduction of photogenerated LOOHs results in a surge of lipid peroxidation that amplifies dye loss via free radical processes. MC540 bleaching might be exploited as a relatively simple and sensitive indicator of lipid autoxidation in isolated membranes and cells.

Antioxidants↗
PubMed1994

Selective RNA editing and subunit assembly of native glutamate receptors.

RNA editing and subunit assembly of ionotropic glutamate receptors (GluRs) were examined in an oligodendrocyte progenitor cell line, CG4, which expresses GluR2-GluR4, GluR6, GluR7, KA1, and KA2. AMPA-evoked currents rapidly desensitize, whereas kainate-evoked currents contain a steady-state component with a nearly linear current-voltage relation and a fast desensitizing component that is inwardly rectifying. The Q/R site is edited > 95% to the arginine codon in GluR2(Q607) mRNA, and < 5% in GluR6(Q621) mRNA. Immunoprecipitation experiments demonstrate that GluR6 and/or GluR7 subunits assemble with KA2, but not with GluR2-GluR4. These results indicate that oligodendrocyte progenitor cells selectively edit and assemble glutamate receptors into at least two functionally and structurally distinct heteromeric channels.

Animals↗
PubMed1994

Goblet cell carcinoid of the appendix.

BACKGROUND: Over the past 15 years, a variant of appendiceal carcinoid has been recognized which is not widely known to the general surgeon. This tumor, variously labeled adenocarcinoid or goblet cell carcinoid, has a more aggressive natural history than classic appendiceal carcinoids and requires a different surgical approach. PATIENTS AND METHODS: A survey of the tumor registries of 10 hospitals identified 7 female and 2 male patients with goblet cell carcinoid of the appendix between 1983 and 1993. The clinical data of these patients were reviewed. RESULTS: Median age was 58 years (range 31 to 73). Clinical presentation followed two distinct patterns: acute onset suggestive of appendicitis or chronic symptoms associated with a pelvic mass. In no case was the diagnosis suspected preoperatively or established intraoperatively. Four patients with discrete distal appendiceal tumors treated with appendectomy are alive without evidence of disease 2 to 11 years since their diagnoses. The 5 patients with diffuse appendiceal involvement all had intra-abdominal metastases. Four are dead of disease at intervals from 5 months to 2 years postdiagnosis. CONCLUSIONS: Goblet cell carcinoids are a distinct clinical and pathologic entity with variable malignant potential. Patients with diffuse appendiceal involvement require aggressive surgery as part of multimodal therapy.

Adult↗
PubMed1994

A comparison of the sensitivity of blood and bone marrow for the detection of minimal residual disease in chronic myeloid leukaemia.

We have sought to determine whether peripheral blood or bone marrow is more sensitive for assessment of minimal residual disease in chronic myeloid leukaemia (CML). Contemporaneous blood and marrow specimens were taken from 21 patients at various times after allogeneic bone marrow transplant (BMT) and from one patient in complete cytogenetic remission on alpha-interferon. Samples were analysed for evidence of BCR-ABL mRNA by RT-PCR: four were PCR negative and 19 PCR positive. Results with blood and marrow were concordant in all cases. BCR-ABL transcripts were quantified in PCR-positive samples using a competitive PCR titration assay. Results ranged from < 10 to 2 x 10(6) BCR-ABL transcripts/micrograms RNA. In all 19 cases a high degree of concordance in BCR-ABL levels with blood and marrow (r = 0.99) was found. We conclude that either tissue may be used for residual disease studies after BMT for CML.

Bone Marrow↗
PubMed1994

Aplasia after donor lymphocyte infusion (DLI) for CML in relapse after sex-mismatched BMT: recovery of donor-type haemopoiesis predicted by non-isotopic in situ hybridization (ISH).

We report a patient with CML in relapse after a sex-mismatch bone marrow transplant who was treated with donor lymphocyte infusions and developed severe marrow aplasia 3 months later. As cytogenetic analysis at this point was not possible because of the very low number of marrow cells available, we used in situ hybridization (ISH) for sex chromosomes and the BCR/ABL gene together with quantitative PCR to monitor the patient's response. The results suggest that recovering haemopoiesis was derived from donor cells and contributed to the decision not to transfuse donor marrow cells on a second occasion.

Adult↗
PubMed1994

Cytoprotection against merocyanine 540-sensitized photoinactivation of the Na+,K(+)-adenosine triphosphatase in leukemia cells: glutathione and selenoperoxidase involvement.

When irradiated with broad-band visible light in the presence of merocyanine 540 (MC540), murine leukemia L1210 cells grown under selenium-deficient conditions (Se(-) cells) accumulated lipid hydroperoxides and lost viability more rapidly than selenium-satisfied (Se(+) cells). These findings suggest that cytoprotection against photoperoxidation and photokilling is mediated at least in part by selenoperoxidase (SePX) action. Similar protection against photoinactivation of an intrinsic membrane enzyme, the Na+,K(+)-ATPase, has been observed. Thus, irradiation of MC540-sensitized Se(-) cells resulted in an immediate and progressive inactivation of ouabain-sensitive Na+,K(+)-ATPase; by contrast, activity loss in Se(+) cells was preceded by a prominent lag. Enzyme photo-inactivation in Se(-) cells was inhibited by ebselen, an SePX mimetic, confirming that SePX(s) is (are) involved in natural protection. Desferrioxamine treatment (iron sequestration/inactivation) resulted in higher hydroperoxide levels and slower Na+,K(+)-ATPase inactivation during MC540/light exposure, whereas ferric-8-hydroxyquinoline treatment (iron supplementation) had the opposite effect. Thus, iron appears to play an important role in both of these processes. In contrast, photoinactivation of another intrinsic enzyme in L1210 cells, acetylcholinesterase (AChE), was unaffected by selenium or iron manipulation. On the basis of these findings, we propose that lipid peroxidation plays an important role in the photoinactivation of Na+,K(+)-ATPase, but not AChE. This is consistent with the fact that Na+,K(+)-ATPase's active site lies within the membrane bilayer, whereas AChE's active site lies outside the bilayer.

Animals↗
PubMed1994

Wild-type gas vesicle formation requires at least ten genes in the gvp gene cluster of Halobacterium halobium plasmid pNRC100.

To study the functions of the 13 gvp genes, gvpMLKJIHGFEDACN, on plasmid pNRC100 of Halobacterium halobium in gas vesicle formation, we carried out linker scanning mutagenesis of the gene cluster. We constructed a 24.5-kb Escherichia coli-H. halobium shuttle plasmid, pFL2, containing the gvp gene cluster and introduced a kanamycin resistance (kappa) cassette into each gene (except for gvpA). Transformation of H. halobium SD109, which had the entire gvp gene cluster deleted, with pFL2 and mutated pFL2 derivatives showed that while the unmutated gene cluster successfully programmed gas vesicle formation, derivatives with insertion of the kappa cassette in any of the gvp genes, except gvpM, did not lead to production of normal gas vesicles. Insertions in gvpL, -K, -J, -I, and -F resulted in a complete block in gas vesicle synthesis, while insertions in gvpH, -G, -E, -D, -C, and -N resulted in greatly reduced gas vesicle synthesis. In most cases, the block in gas vesicle synthesis did not result from polar effects, since similar results were obtained for derivatives of the insertion mutants in which most of the internal portion of the kappa cassette was deleted and only small (15 to 54-bp) insertions remained. The only exceptions were for gvpH and gvpD, where deletion of the internal portion of the kappa insertions resulted in phenotypic reversion. Electron microscopic analysis of the kappa mutants revealed that interruptions of gvpC and gvpN result in the formation of smaller gas vesicle than in the wild type, while interruptions of gvpF, -G, -H, -J, -K, and -L produce no discernible vesicle intermediates. These results indicate the gvpA, -C, and -N, which have the rightward transcriptional orientation, encode structural proteins, with gvpC and gvpN necessary for late stages of vesicle formation, and gvpL, -K, -J, -I, -H, -G, and -F, which have the leftward transcriptional orientation encode proteins involved in early steps in the assembly of gas vesicles.

DNA Transposable Elements↗
PubMed1994

Both open and closed NMDA receptor channels desensitize.

Desensitization of NMDA receptors was studied at the single-channel level using outside-out patches taken from rat hippocampus CA neurons maintained short term in culture. The amount of desensitization that accumulated as a function of time during the application of NMDA (2.5 microM) was measured by the response to the rapid application of NMDA at a high concentration (100 microM). Records were sorted into two classes: those in which no openings were detected during the application of 2.5 microM NMDA, and those in which some channel openings occurred. Analysis of these data reveals that some desensitization accumulated when no channels opened, but that more desensitization developed when channels opened. The observations indicate that channels can pass from the closed state to the desensitized state, but that desensitization occurs more rapidly from the open state.

Animals↗
PubMed1994

Detection of residual leukaemia more than 10 years after allogeneic bone marrow transplantation for chronic myelogenous leukaemia.

The clinical status of a homogeneous cohort of long-term survivors of allogeneic marrow transplantation was assessed and residual leukaemia was studied by reverse transcription polymerase chain reaction for leukaemia specific BCR-ABL mRNA. The group comprised 34 consecutive patients with CML in chronic phase treated by chemoradiotherapy and transplantation of bone marrow from HLA-identical sibling donors between February 1981 and December 1983 in the joint Hammersmith-Northwick Park programme. The probability of survival at 10 years was 59 +/- 17%. Eighteen of the 19 surviving (95%) patients have Karnofsky scores of 90 or 100% indicative of a good performance status. One of the survivors had evidence of relapse 6.5 years after transplant but has since been restored to complete remission by treatment with interferon-alpha followed by donor leucocyte transfusions. Surprisingly, 2 of the 19 patients who have been in remission for over 10 years have molecular evidence of persisting leukaemic cells. Quantification by competitive PCR indicated that the malignant clone persisted at low levels. The data suggest that the majority of long-term survivors after BMT for CML are in good health and may be regarded as cured. Some long-term survivors, however, may still harbour residual leukaemic cells and continued monitoring for late relapse is warranted. Late relapse is amenable to further therapy with leukocyte transfusions from the original marrow donor.

Adult↗
PubMed1994

Endoscopic ultrasound-guided fine needle aspiration of pancreatic carcinoma.

Endoscopic ultrasound (EUS) is reported to be the single best modality for visualizing small pancreatic carcinomas. Whereas tissue diagnosis by fine needle aspiration (FNA) can be performed with computed tomography (CT) or transabdominal ultrasound guidance, the diagnostic accuracy is limited by the ability of these modalities to visualize the lesion. Real time EUS-guided fine needle aspiration has recently been reported as a new diagnostic modality. The application of EUS-guided FNA in the diagnosis of small pancreatic carcinoma has not been reported. We present a case in which transduodenal EUS-guided FNA was successful in establishing a definitive tissue diagnosis of pancreatic carcinoma in a 1.6-cm lesion in the head of the pancreas. This case along with a review of the literature highlights the great potential of this new modality in the diagnosis of pancreatic carcinoma.

Adenocarcinoma↗
PubMed1993

Hyperexpression of catalase in selenium-deprived murine L1210 cells.

Murine leukemia L1210 cells grown for 2-3 weeks in the presence of 1% serum without selenium supplementation [L.Se(-) cells] typically exhibited < 10% of the glutathione peroxidase (GPX) and phospholipid hydroperoxide glutathione peroxidase (PHGPX) activity of selenium-satisfied controls [L.Se(+) cells]. Concomitant with diminished GPX and PHGPX activity was a 1.5- to 2.0-fold increase in catalase (CAT) activity, which reverted to control levels when L.Se(-) cells were given sufficient Se for full expression of selenoperoxidase activity. Selenium manipulation affected total glutathione content similarly, but had no effect on glutathione-S-transferase or superoxide dismutase activity. Long-term growth under Se-deficient conditions resulted in a progressive additional increase in CAT activity, which maximized after ca. 5 months. These cells [referred to as L'.Se(-)] attained CAT activity levels at least 100-times greater than those of Se-supplemented [L'.Se(+)] controls, whereas their glutathione content remained elevated by approximately 70%. Supplying L'.Se(-) cells with Se resulted in a rapid elevation to full GPX activity; however, CAT failed to decline in this case, suggesting that a selection for stable CAT hyperexpressing variants had been accomplished. Quantitative immunoblot analysis indicated that the high CAT activity of L'.Se(-) cells is accounted for by an elevated level of enzyme protein. Induction of CAT and selection for CAT-rich phenotypes, as apparent for Se-starved L1210 cells, was not observed in human K562 counterparts, which lack GPX and express only a low level of PHGPX. L.Se(-) cells were found to be more sensitive to H2O2-induced killing than L.Se(+) controls, whereas L'.Se(-) cells were exceedingly more resistant to H2O2 than L'.Se(+) counterparts. By contrast, L.Se(-) and L'.Se(-) cells were both more sensitive to t-butyl hydroperoxide than Se(+) controls, consistent with CAT being unimportant in the detoxification of this peroxide compared with GPX. This appears to be the first reported evidence for CAT hyperexpression in response to selenium deprivation.

Animals↗