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Biomedical subjects

L Thomas

Publications and source records attributed to L Thomas.

At least 343 records · Page 19Linked to original sources
PubMed1990

Sustained effectiveness of an atrial antitachycardia pacemaker during follow-up.

Atrial antitachycardia pacemakers are indicated for medically refractory atrial tachyarrhythmias. To confirm long-term device effectiveness, we studied diagnostic data obtained in 17 patients with atrially-placed Intermedic "Intertach" pacemakers. The unit has programmable primary (P mod) and secondary (S mod) antitachycardia response protocols. Success of the P mod was defined as a P mod response first with no subsequent S mod response. Follow-up was for 595 days (+/- 302 days). The P mod was utilized first 88.2 +/- 102 times per patient interrogation with subsequent S mod use 21.1 +/- 53 times (P less than 0.0001). Results were also significant when P mod was compared to S mod in the first versus the last half of follow-up (both P less than 0.0001). These results suggest that the programmed P mod of the atrial "Intertach" tachycardia reversion pacemaker has sustained effectiveness in the treatment of medically refractory atrial tachyarrhythmias.

Atrial Flutter↗
PubMed1990

Immunocytochemical examination of bone marrow in disseminated neuroblastoma.

To assess the usefulness of immunocytochemical analysis of bone marrow in patients with neuroblastoma, marrow smears from 33 staging procedures in 12 patients were examined using an indirect immunoalkaline phosphatase technique with monoclonal antibodies raised against human neural tissue. Marrow aspirate and trephine collagenase digest specimens from individual sites were each tested with the monoclonal antibody UJ13A and with a pool of three related antibodies. The results were compared with morphological assessment of conventionally stained aspirates and trephine specimens taken at the same time. Immunostaining suggested the presence of tumour in seven of 18 staging procedures in which conventional techniques had shown infiltration. Tumour infiltration was also suggested in four of 10 staging procedures with suspicious trephine specimens, but in none of three with relatively innocent histological and cytological features. Immunological investigation provides no additional information about the presence of infiltration if conventional microscopy has shown definite tumour. When histological appearances are suspicious, immunostaining of stored aspirate smears or collagenase digest specimens may provide evidence of infiltration. There are insufficient data to comment on the value of immunostaining when conventional techniques reveal "normal" marrow, but the impression gained from this study is that immunostaining has a limited role in the detection of metastatic neuroblastoma, which yet remains to be defined.

Bone Marrow↗
PubMed1990

[Clinical application of grafts of cultured epidermis in burn patients. Apropos of 16 patients].

The authors report a series of 16 patients with extensive burns partially treated by epidermal culture between May 1985 and July 1988. This series consisted of 9 males and 7 females between the ages of 6 and 88 years (mean age: 34 years). The mean surface area of the burns was 66% (range: 30% to 92%). The technique of epidermis culture used was derived from that developed by Green and Rheinwald. A fragment of full-thickness skin taken from the patient was subjected to the action of trypsin. The keratinocytes were cultured on nutrient layers of 3T3 cells. After 10 days, the secondary cultures corresponded to stratified squamous epithelium with a differentiation similar to that of normal human epithelium. This cultured epithelium was used for autografts as well as allografts. Three deaths were related to septic or metabolic complications of the burn. The take rate of the initial graft was greater than 50% in 9 patients. In 3 patients the graft take rate was less than 50% and in 4 patients it was nil. The long-term evaluation of 12 patients revealed partial lysis of the grafts in 3 patients, a stable result in 6 patients and a healed surface greater than the grafted surface in three cases. The best results were obtained with autografts. The initial evaluation of taking of the graft is difficult, as the fine and shiny texture of the grafts is sometimes difficult to distinguish from non-covered zones. The good tolerance of cultured epidermis allografts is due to the fact that they are devoid of Langerhans cells. Although controversial, the reality of the taking of these allografts opens the way to establishing epidermis culture banks.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

[Long-term clinical course after second laparotomy in ovarian cancer].

A series of thirty consecutive epithelial ovarian cancer patients were reviewed after long-term follow-up (more than 5 y) since their second-look operation (SLO). All patients had advanced tumors (stages IIb-IV). Primary chemotherapy consisted of a cisplatin-associated regimen. For all patients adjuvant treatment had been planned after completion of the SLO. Mean follow-up after SLO was 68 months (47-103 months). Tumor status at SLO divided the patients in 2 subgroups: Group A = 13 patients (43%), with no evidence of histologically proved disease at time of operation (NED); Group B = 17 patients (57%), with macroscopic persistence of tumor. Survival was significantly better in the first group than in the second (77% at 5 yr vs less than 25%). Recurrence rate in the NED group was 7.7% (1 recurrence at 32 months). Eight of 17 patients with gross tumor at SLO underwent satisfactory resection. However, recurrence rate was high (75%) and survival rate was low (25% at 5 yrs). This result was not significantly better than that of patients with no optimal resection at SLO (9 patients, survival 22%). Second effort resection at SLO does not seem to be beneficial in these patients after partial failure of initial chemotherapy with cisplatin. The usefulness of systematic second look operations is discussed. Controlled randomized trials should be made to determine the exact role of SLO in ovarian cancer treatment.

Adult↗
PubMed1990

[Venous stasis and orthostasis as factors influencing fructosamine concentration].

The concentrations of high molecular weight blood constituents are influenced by the increased intravascular pressure at sample collection. The impact on the fructosamine concentration was compared with that on total protein, plasma protein, electrolytes, and protein bound analytes such as calcium. The results show that fructosamine concentration behaves similar to that of total protein and albumin with change in resting position and venous-stasis.

Adult↗
PubMed1990

[Changes in the plasma protein concentration as a factor influencing the fructosamine value].

Fructosamine values are notably influenced by plasma protein concentration. Total protein concentration in addition to variations in the plasma protein concentrations (Dysproteinemia) play a role here. This is a result of the various glycosylation of the different plasma proteins. Since fructosamine behaves similar to total protein for hypo- and hyperproteinemia, a good relationship with the total protein is expected for normoproteinemia. Hence, no erroneous high nor low fructosamine values are obtained. Dysproteinemia at normal total protein concentration causes no erroneous fructosamine values with the exception of some illnesses. Therefore, a direct relationship between protein and fructosamine at normoproteinemia is not generally necessary.

Blood Proteins↗
PubMed1990

[Cancer of the lips. Results of the treatment of 299 patients].

From 1970 to 1985, 299 patients with carcinoma of the lip were entirely managed at the Bergonié Foundation. Interstitial radiotherapy was most commonly used. It resulted in a successful local control in 96% of cases (238/248), while cosmetic and functional results seemed better than those of surgery. However, surgery seemed more performant for in situ carcinomas, late aggressive T3 carcinomas, local recurrences, as for T4 lesions associated with other techniques. After reviewing the case history of patients with local recurrences, we found technical faults in one half of those managed by interstitial radiotherapy. Local control rates after surgical salvage of recurrences was 99%. Treatment of neck nodes was not discussed in this publication.

Adult↗
PubMed1990

Temporal artery biopsy.

Though surgeons have little input in the selection of patients for temporal-artery biopsy, a knowledge of temporal-artery anatomy and the pathophysiology of temporal arteritis is important. All temporal-artery biopsies done at Carraway Methodist Medical Center between January 1980 and January 1985 were reviewed. Seventy-three biopsies were performed on 70 patients and eight (11.4%) were found to have temporal arteritis histologically. One patient was judged to have temporal arteritis clinically, despite a negative biopsy of short length. Six of eight patients with positive biopsies were female, with an average age of 71.7 years. The most common signs and symptoms of those patients with positive biopsies were temporal headache (8/8), elevated erythrocyte sedimentation rate (7/8), temporal tenderness (5/8), jaw claudication (3/8), and visual changes (3/8). All biopsies were done under local anesthesia and there were no complications. With increasing awareness of the segmental nature of the disease, the length of biopsy specimens (formalin treated) increased from an average of 0.4 cm in 1980 to 2.4 cm in 1984. During this time, the positive rate increased from 0 per cent (0/9) to 17 per cent (4/24). A generous biopsy of approximately 5 cm in length of fresh vessel is recommended to confirm the suspected diagnosis of temporal arteritis.

Aged↗
PubMed1989

Surface-enhanced resonance Raman spectroscopy as an ancillary high-performance liquid chromatography detector for nitrophenol compounds.

In this study, the potential application of surface-enhanced resonance Raman scattering (SERRS) spectroscopy as an off-line secondary detector for HPLC has been evaluated. Four nitrophenol compounds, 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, and 4,6-dinitrocresol were separated by isocratic reverse-phase high-performance liquid chromatography (RP-HPLC) and monitored with a conventional UV detector. Resonance Raman (RR) and SERRS spectroscopy were next used to provide the required specificity for distinguishing the nitrophenol compounds. The SERRS detection limit for both 2-nitrophenol and 4-nitrophenol was calculated to be 14 ppb and that for 2,4-dinitrophenol and 4,6-dinitrocresol was estimated to lie near the parts-per-billion level as well. This detection limit is 2-3 orders of magnitude lower than that obtained by RR spectroscopy.

Chromatography, High Pressure Liquid↗
PubMed1989

[Requests for chemical analysis: growth without end?].

The number of analyses dealt within laboratory medicine increased from 1970 until the middle of the 80s by about 15% per annum in the German Federal Republic. The number of analyses in clinical chemistry, haematology, blood banking and haemostaseology have now reached a plateau. Because these analyses account for 85% of laboratory testing in big hospitals, the problems of rapid growth do not exist any longer. The single most important concern today is the spiralling cast of the remaining 15% of analyses, in the fields of serology, tumour diagnosis and monitoring, endocrinology, drug monitoring and microbiology. These investigations, which are rapidly increasing at the rate of about 15% annually, are mainly analyzed by means of the immunoassay technique. Immunoassays are very cost-intensive and, thus, current trends in laboratory medicine are characterized by an overproportional increase in costs with no foreseeable diminution in escalation.

Chemistry, Clinical↗
PubMed1989

Last gasp.

Explore the source record for details and available documents.

Humans↗
PubMed1989

Effects of monensin on ATP levels and cell functions in rat liver and lung in vitro.

Effects of the proton-alkali cation-exchanging ionophore, monensin, on aspects of cellular metabolism and ionic exchanges have been studied in rat tissues in vitro. Incubation of liver slices at 38 degrees C with 0.1 microM monensin induced time-dependent vesiculation, initially in the Golgi region, reduction of ATP content and of protein synthesis. At 1 microM, monensin also reduced net, active movements of K+, Na+, Cl- and water in liver slices and inhibited state 3 respiration in isolated mitochondria. The respiratory inhibitor, amytal, similarly reduced ATP content and protein synthesis at concentrations lower than those inhibiting ion transport in slices. Low concentrations of monensin (0.1-1.0 microM) had similar effects on ATP and ion transport in slices of adult lung. By contrast, late-fetal liver and lung were much less sensitive to monensin; in these tissues, glycolysis sustained substantial levels of ATP. Monensin also induced vesiculation of the Golgi apparatus in fetal lung cells. It is concluded that by lowering ATP levels, monensin can markedly alter various metabolic activities in those cells which depend primarily on oxidative phosphorylation for their metabolic energy.

Adenosine Triphosphate↗
PubMed1989

Human umbilical cord blood as a potential source of transplantable hematopoietic stem/progenitor cells.

The purpose of this study was to evaluate human umbilical cord blood as an alternative to bone marrow in the provision of transplantable stem/progenitor cells for hematopoietic reconstitution. Although no direct quantitative assay for human hematopoietic repopulating cells is at present available, the granulocyte-macrophage progenitor cell (CFU-GM) assay has been used with success as a valid indicator of engrafting capability. We examined greater than 100 collections of human umbilical cord blood for their content of nucleated cells and granulocyte-macrophage, erythroid (BFU-E), and multipotential (CFU-GEMM) progenitor cells, in many cases both before and after cryopreservation. First it was determined that granulocyte-macrophage, erythroid, and multipotential progenitor cells remained functionally viable in cord blood untreated except for addition of anticoagulant for at least 3 days at 4 degrees C or 25 degrees C (room temperature), though not at 37 degrees C, implying that these cells could be satisfactorily studied and used or cryopreserved for therapy after transport of cord blood by overnight air freight carriage from a remote obstetrical service. Granulocyte-macrophage progenitor cells from cord blood so received responded normally to stimulation by purified recombinant preparations of granulocyte-macrophage, granulocyte, and macrophage colony-stimulating factors and interleukin 3. The salient finding, based on analysis of 101 cord blood collections, is that the numbers of progenitor cells present in the low-density (less than 1.077 gm/ml) fraction after Ficoll/Hypaque separation typically fell within the range that has been reported for successful engraftment by bone marrow cells. Another observation of practical importance is that procedures to remove erythrocytes or granulocytes prior to freezing, and washing of thawed cells before plating, entailed large losses of progenitor cells, the yield of unwashed progenitor cells from unfractionated cord blood being many times greater. The provisional inference is that human umbilical cord blood from a single individual is typically a sufficient source of cells for autologous (syngeneic) and for major histocompatibility complex-matched allogeneic hematopoietic reconstitution.

Blood Preservation↗
PubMed1989

Expression of Drosophila Shaker potassium channels in mammalian cells infected with recombinant vaccinia virus.

A recombinant vaccinia virus containing a Drosophila potassium channel (Shaker H4) cDNA was constructed by homologous recombination between wild-type vaccinia virus DNA and a transfer plasmid. The new virus was used to infect four types of mammalian cells in culture. Electrophysiological recording 24-72 hr after infection revealed the expression of voltage-gated transient potassium channels in all four cell types. The properties of the induced currents were identical to those previously observed following injection of the Shaker H4 transcript into oocytes. Vaccinia promises to be an effective vehicle for the heterologous expression of transmembrane ion channels in a variety of cell types.

4-Aminopyridine↗