Systematic success in prosthodontics.
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Appointments and Schedules↗
Biomedical subjects
D Schwab
Publications and source records attributed to D Schwab.
Lessons from a marketeer.
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Economic Competition↗
Today's impatient patient.
Fee-for-service dentists face the daily challenge of differentiating themselves from discount providers while delivering quality care to patients pressed for time. Some thoughts on how to make the best of limited time.
Appointments and Schedules↗
Uptake of 3 alpha, 7 alpha, 12 alpha-trihydroxy-24-nor-5 beta-cholan-23-sulfonate into isolated rat hepatocytes by three transport systems.
Uptake of norcholansulfonate (3 alpha, 7 alpha, 12 alpha-trihydroxy-24-nor-5 beta-cholan-23-sulfonate), an isogeometric analogue of cholate into isolated rat liver hepatocytes occurs only by saturable transport. In order to identify the transport systems involved, uptake of norcholansulfonate was studied using 7 beta-NBD-NCT ({N-[7-(4-nitrobenzo-2-oxa-1,3-diazol)]-7 beta-amino-3 alpha,12 alpha-dihydroxy-5 beta-cholan-24-oyl})-2'-aminoethanesulfonate) as a competing substrate. For transport of both bile salt derivatives, which mutually inhibit their mediated transport competitively, the existence of at least three transport systems must be assumed. Uptake studies using the cloned hepatic Na+/cholyltaurine cotransporting polypeptide stably expressed in CHO cells (Chinese hamster ovary cells) showed that both bile salt derivatives were transported and furnished the definite KT values of this single transport system and the ratio of the maximal uptake velocities. On the basis of these data, uptake of both bile salt derivatives into rat hepatocytes and their mutual competitive inhibition could be analyzed for three transport systems. The maximal flux rates J2 and the half-saturation constants KT2 in the presence of Na+ (143 mM) are for norcholansulfonate: J1(Na+ 143) = 1.0 +/- 0.2 nmol/(min . mg protein), KT1(Na+ 143) = 15 +/- 4 microM, J2(Na+ 143) = 0.5 +/- 0.2 nmol/(min.mg protein), KT2(Na+ 143) = 15 +/- 2 microM, J3(Na+ 143) = 0.5 +/- 0.2 nmol/(min.mg protein), KT3(Na+ 143) = 60 +/- 15 microM, and for 7 beta-NBD-NCT J1(Na+ 143) = 0.14 +/- 0.04 nmol/(min.mg protein), KT1(Na+ 143) = 3.1 +/- 0.5 microM, J2(Na+ 143) = 0.014 +/- 0.005 nmol/(min.mg protein), KT2(Na+ 143) = 21 +/- 2 microM, J3(Na+ 143) = 1.0 +/- 0.1 nmol/(min.mg protein), KT3(Na+ 143) = 190 +/- 25 microM. The kinetic parameters are in accordance with the assumptions that the cloned Na+/cholyltaurine cotransporting polypeptide represents transport system 2 and that the kinetically identified additional transport system 1 is either strictly or partially Na(+)-dependent.
Animals↗
p53 mutation and locoregional treatment failure in head and neck squamous cell carcinoma.
BACKGROUND: The p53 gene (also known as TP53) may be the most common genetic target involved in the malignant transformation of human cells. Direct sequence analysis has demonstrated that alteration of this gene occurs in approximately 45% of head and neck squamous cell carcinomas. The consequences of p53 mutations in these cancers with respect to tumor behavior and patient survival have not been rigorously determined. PURPOSE: We evaluated the implications of p53 mutations in relation to the control of locoregional disease and overall survival following radiation therapy. METHODS: Data from 110 consecutive patients with invasive disease who were treated with primary radiation therapy (given with curative intent) or with adjuvant radiation therapy (following complete surgical extirpation of gross disease) were included in the analysis. A 1.8-kilobase fragment of the p53 gene encompassing exons 5-9 was amplified from the DNA of stored (frozen) tumor specimens; the amplified DNA was cloned and sequenced by use of standard techniques. Overall survival and locoregional disease-free survival after the completion of radiation therapy were estimated by the Kaplan-Meier method; survival comparisons were made by use of the logrank test or proportional hazards regression models. Reported P values are two-sided. RESULTS: Fortyeight (44%) of the 110 tumors had cells bearing p53 mutations. The risk of locoregional recurrence following either primary or adjuvant radiation therapy was significantly greater (i.e., the time to recurrence was shorter) for patients whose tumors contained mutant p53 genes (univariate model hazard ratio [HR] for p53 mutation versus wild-type = 2.2; 95% confidence interval [CI] = 1.2-4.1; P = .02). The presence of regional lymph node metastases (presence versus absence, HR = 2.0; 95% CI = 1.0-4.2; P = .05) and treatment type (primary radiation therapy versus surgery plus adjuvant radiation therapy, HR = 2.3; 95% CI = 1.2-4.3; P = .01) were also associated with greater risks of locoregional failure. The presence of p53 mutations and lymph node metastases and treatment with primary, as opposed to adjuvant, radiation therapy remained significant risk factors in multivariate regression analysis. No relationship was demonstrated between p53 status and overall survival (mutant versus wild-type, HR = 1.1; 95% CI = 0.6-2.1; P = .66); however, a relationship was shown for tumor stage and overall survival (stages III and IV [more advanced] versus stages I and II [less advanced], HR = 3.3; 95% CI = 1.0-10.8; P = .05). Mutation of the p53 gene was not associated with patient age, sex, tumor stage, primary tumor site, regional lymph node status, degree of tumor cell differentiation, or treatment method. CONCLUSIONS: Mutation of the p53 gene is associated with an increased risk of locoregional failure in patients with invasive head and neck squamous cell carcinoma who are treated with radiation therapy.
Carcinoma, Squamous Cell↗
Molecular analysis of effectiveness of Mohs' surgical technique.
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Aged↗
Molecular detection of primary bladder cancer by microsatellite analysis.
Microsatellite DNA markers have been widely used as a tool for the detection of loss of heterozygosity and genomic instability in primary tumors. In a blinded study, urine samples from 25 patients with suspicious bladder lesions that had been identified cystoscopically were analyzed by this molecular method and by conventional cytology. Microsatellite changes matching those in the tumor were detected in the urine sediment of 19 of the 20 patients (95 percent) who were diagnosed with bladder cancer, whereas urine cytology detected cancer cells in 9 of 18 (50 percent) of the samples. These results suggest that microsatellite analysis, which in principle can be performed at about one-third the cost of cytology, may be a useful addition to current screening methods for detecting bladder cancer.
Adult↗
p53 and p21(WAF1/CIP1/SDI1) gene products in Barrett esophagus and adenocarcinoma of the esophagus and esophagogastric junction.
The WAF1 (CIP1/SDI1) gene encodes a cyclin-dependent kinase inhibitor which is induced by wild-type, but not mutated, p53 gene product. WAF1 immunohistochemistry has been suggested to clarify the phenotype of overexpressed p53 gene product. We evaluated both p53 and WAF1 gene products by immunohistochemistry in 98 esophagectomy specimens with Barrett esophagus and/or adenocarcinoma of the esophagus and esophagogastric junction. Diffuse positive p53 staining was found in 40 of 88 adenocarcinomas (45%) and in dysplastic Barrett epithelium in 20 of 65 cases (31%), but not in Barrett mucosa without dysplasia (n = 36, P = .0004). Eighty-eight percent of cancers exhibited WAF1 expression, but there was no association with p53 and WAF1 staining. WAF1 protein was also identified in Barrett epithelium and in esophageal squamous and gastric epithelium. In contrast to carcinomas, a unique pattern of mutually exclusive p53 and WAF1 expression was found in five cases of dysplastic Barrett epithelium; a missense mutation at codon 175 of p53 was identified in one. p53 staining of adenocarcinoma was associated with shorter patient survival but was not independent of stage; WAF1 status added no prognostic information. Our findings show that WAF1 immunohistochemistry complements p53 immunohistochemistry in some cases of Barrett dysplasia but not in adenocarcinomas. Positive p53 immunostaining can serve to confirm a neoplastic process in Barrett mucosa. Positive staining of adenocarcinomas may be an indication of advanced stage.
Adenocarcinoma↗
3 alpha, 7 alpha, 12 alpha-trihydroxy-24-nor-5 beta-cholan-23-sulfonate: synthesis and suitability for the study of cholate transport.
In order to facilitate the study of transport processes of unconjugated C-24 bile salts, simple syntheses of 3 alpha, 7 alpha, 12 alpha-trihydroxy-24-nor-5 beta-cholan-23-sulfonate (norcholansulfonate) and 3 alpha, 7 alpha, 12 alpha-trihydroxy-24-nor-5 beta-[7 beta 5H] cholan-23-sulfonate were devised. The hydrophilic-hydrophobic properties of norcholansulfonate, as determined by its chromatographic behavior as well as by its partition between l-octanol and water, are more similar to those of cholyltaurine than to those of cholate. Self-association of norcholansulfonate in phosphate buffer, pH 7.4, with an ionic strength of 150 mM begins at a concentration of about 1 mM, comparable to that of cholyltaurine and cholate, as determined by spectral changes in fluorescence emissions of {N-[7-(4-nitrobenzo-2-oxa-1, 3-diazol)]-7b-amino-3a, 12a-dihydroxy-5b-cholan-24 - oyl}-2'-aminoethanesulfonate (7 beta-NBD-NCT). The apparent CMC value obtained from solubilization of the dye Orange OT, 8.5 mM, is comparable to that of cholytaurine. 7.5 mM, and lower than that of cholate, 9.5 mM. Norcholansulfonate is readily taken up by rat liver and completely excreted unmetabolized into bile with about the same secretion maximum (Tm) as cholyltaurine. Biliary excretion of norcholansulfonate is inhibited by cholyltaurine, and, vice versa, norcholansulfonate inhibits cholyltaurine secretion. Concerning metabolism and excretion, norcholansulfonate with the sulfonate group in the position where cholate has the carboxylate group should behave as an appropriate cholate analogue in mediated transport processes.
Animals↗
Interferon gamma enhances lymphokine-activated killer cell adhesion but not lysis of head and neck squamous cell carcinoma.
OBJECTIVES: To determine if treatment with recombinant human interferon gamma (rHuIFN-gamma) increases the adhesion to, and lysis of, head and neck squamous cell carcinoma (SCC) cells by lymphokine-activated killer (LAK) and peripheral blood mononuclear (PBM) effector cells in vitro and to evaluate the role of cell surface adhesion molecules in these processes. DESIGN: Two human SCC cell lines, JHU-020-SCC and JHU-022-SCC, were used. Lymphokine-activated killer cells were generated by interleukin-2 stimulation of PBM cells obtained from the hemapheresis blood donor packs of healthy individuals. Adhesion assays were performed to assess the level of binding of both effector populations to SCC cells, which were treated with either fresh media or rHuIFN-gamma (100 U/mL). Binding was measured by flow cytometric detection of effector cells labeled with fluorescein-conjugated anti-CD45 monoclonal antibody. Monoclonal antibodies to the cell adhesion molecules HLA-DR, lymphocyte function-associated antigen 1, and intercellular adhesion molecule 1 were used in blocking experiments to determine their contribution to the process of effector-SCC cell adhesion. Cytotoxicity experiments were performed using a colorimetric assay to determine the cytotoxic response generated by LAK and PBM cells against SCC cells, with and without prior rHuIFN-gamma treatment of the tumor cells. MAIN OUTCOME MEASURES: Effector cell binding level and percent cytotoxicity of SCC cells. RESULTS: Recombinant human interferon gamma treatment of JHU-020-SCC cells resulted in increased adhesion to both LAK cells and PBM cells (P < .001). The presence of anti-lymphocyte function-associated antigen 1 antibody resulted in elimination of the enhanced adhesion seen with rHuIFN-gamma pretreatment of SCC cells (P =.03), but antibody to intercellular adhesion molecule 1 and HLA-DR did not reduce the level of effector binding. The greatest cytotoxic response against both JHU-020-SCC and JHU-022-SCC was seen with LAK cells (P < or = .001). Pretreatment of tumor targets by rHuIFN-gamma (100 U/mL) resulted in no enhancement of cytotoxic response by either LAK or PBM cells; at the effector-target ratio of 30:1, there was a significant decrease in LAK cell-mediated cytotoxic response against rHuIFN-gamma-treated SCC cells (P < or = .02). CONCLUSIONS: Recombinant human interferon gamma treatment of head and neck SCC cells does increase binding of both LAK cells and PBM cells to tumor cells, in part via the lymphocyte function-associated antigen 1 ligand mechanism. The cytotoxic effect mediated by LAK cells against head and neck SCC cells is reduced after rHuIFN-gamma treatment, suggesting that the activity of this cytokine may be more important in regulating antigen-specific cytotoxic response mediated by cytotoxic T-lymphocytes.
Antineoplastic Agents↗
Frequency of homozygous deletion at p16/CDKN2 in primary human tumours.
Many tumour types have been reported to have deletion of 9p21 (refs 1-6). A candidate target suppressor gene, p16 (p16INK4a/MTS-1/CDKN2), was recently identified within the commonly deleted region in tumour cell lines. An increasing and sometimes conflicting body of data has accumulated regarding the frequency of homozygous deletion and the importance of p16 in primary tumours. We tested 545 primary tumours by microsatellite analysis with existing and newly cloned markers around the p16 locus. We have now found that small homozygous deletions represent the predominant mechanism of inactivation at 9p21 in bladder tumours and are present in other tumour types, including breast and prostate cancer. Moreover, fine mapping of these deletions implicates a 170 kb minimal region that includes p16 and excludes p15.
Blotting, Southern↗
Rates of p16 (MTS1) mutations in primary tumors with 9p loss.
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Carrier Proteins↗
Heterogeneity in hepatic transport of somatostatin analog octapeptides.
Hepatic transport of the synthetic somatostatin analog octreotide-SMS 201-995, (D)Phe-Cys-Phe-(D)Trp-Lys-Thr-Cys-Throl--and its novel derivative N-alpha-(alpha-D-glucosyl(1-4)-1-deoxy-D-fructosyl)-octreotide--SD Z CO-611, N-alpha-(alpha-D-glucosyl(1-4)-1-deoxy-D-fructosyl)-(D)Phe-Cys-Phe- (D)Trp-Lys-Thr-Cys-Throl--was studied. In rats SMS 201-995 showed a plasma elimination half-life of 1.2 +/- 0.2 hr; that of SDZ CO-611 was 1.9 +/- 0.3 hours. Within 120 min 66% of a mesenterically injected 4.4-nmol dose of SMS 201-995 was excreted in bile, but only 5.3% of SDZ CO-611 was excreted in bile. Biliary concentration of SMS 201-995 showed a maximum enrichment of 540-fold +/- 75-fold over peripheral blood concentration, indicating hepatic transport mechanisms different from simple diffusion. Comparison of plasma profiles of both peptides after mesenteric and femoral administration demonstrated the relative importance of hepatic extraction for SMS 201-995 but not for SDZ CO-611. The mode of extraction was studied by means of multiple-indicator dilution in isolated perfused rat liver, with inulin as nonpermeable marker. Ratio plots, ln([inulin]/[peptide]) vs. time, exhibited decreasing slopes for SMS 201-995, suggesting very rapid binding to hepatocyte membranes. The slope of the ratio plot of (inulin/SDZ CO-611) was almost zero even at low doses (down to 0.2 microgram), implying mainly extracellular distribution and nonhepatic elimination. Binding assays indicated the absence of somatostatin receptors in sinusoidal hepatocyte membranes. However, SMS 201-995 and SDZ CO-611 bound with high affinity to somatostatin receptors in rat cortical membranes. Multiple-indicator dilution experiments in presence of increasing cholyltaurine concentrations suggested an interaction of SMS 201-995 with sinusoidal bile salt transport. In isolated hepatocytes, uptake of SMS 201-995 was saturable and showed mutual inhibition with cholyltaurine. The results indicate that SMS 201-995 transport is different from receptor mediated endocytosis as known for peptide hormones and elimination pathways of SDZ CO-611 other than biliary excretion.
Animals↗
Ruffling and locomotion: role in cell resistance to growth factor-induced proliferation.
It has long been known that the growth rate of cells in vitro can be retarded by providing substrates of restricted area. Such experiments were performed with adhesive islets, made by depositing metals onto agarose layers through templates of various sizes. Since normal cells are unable to adhere to agarose, they become confined to the metallic surface. Using such haptotactic islets, we have studied the role of membrane ruffling and cell locomotion in the resistance of AG1523 human fibroblasts to growth factor-induced mitogenesis. Cells plated on small substrates, i.e., 2,150 microns 2 in area, initially showed vigorous ruffling, which was suppressed by 8 h after plating but had resumed again by 12 h. In contrast, cells on larger-size islets showed a rapid decline and stabilization of ruffling activity. When the growth rate was measured for single cells cultured on haptotactic islets, it was found to increase linearly from areas of 4,280 microns 2 up to 425,000 microns 2. Since the area needed to saturate the growth response was approximately 50-fold larger than the area occupied by a single cell, the growth inhibition was attributed in part to an interference with locomotion. The implication that locomotion provided positive input into growth control mechanisms was subjected to a direct test by evaluating the effect of nine polypeptide growth factors on the motility of serum-starved cells. All except TGF-beta 1 stimulated movement. Finally, the mitogenic effect of growth factors was measured by [3H]thymidine incorporation and found to be proportional to motile activities, as quantitatively assayed. We conclude that locomotion suppression is a factor in AG1523 cell resistance to growth factor-induced mitogenesis.
Cell Division↗
Surviving practice downturn: a case study in dental marketing.
Unexplained downturns can destroy a healthy practice. This report details the warning signs and offers a blueprint for keeping your practice on track.
Economics↗
Cytolytic anticardiac membrane antibodies in the pathogenesis of myopericarditis.
Antisarcolemmal (ASAs) and antimyolemmal antibodies (AMLAs) are serological hallmarks of inflammatory heart muscle disease. They occur in a similar incidence in postcardiac injury syndromes, sarcoid heart disease or in dilated and hypertrophic cardiomyopathy. Rarely but still notably they are found with increasing age or in coronary artery disease. We therefore examined whether they are truly pathogenetic or whether they also possess properties of 'natural antibodies'. AMLAs and ASAs, like natural antibodies, have specificity for preserved structures on the membrane; they possess cross-reactivity and increase with age. In contrast to natural antibodies, however, they occur frequently after viral stimulation or other forms of trauma, are more often of the IgG and IgA than of the IgM isotype and fix complement in the acute stage of the disease. They also possess cytolytic and cytotoxic properties when incubated in vitro with isolated heart muscle cells. Antigenic mimicry has been demonstrated to be operative, since they are cross-reactive to viral proteins.
Adult↗
[Secondary immunopathogenesis in myocarditis, diseases of the heart muscles and infarct-associated arrhythmia in childhood and adulthood].
In histologically proven or clinically diagnosed perimyocarditis in children and adults alterations in cellular and humoral effector mechanisms are demonstrable: OKIaI-positive B- or activated T-lymphocytes are increased in the peripheral blood, whereas natural killer cell activity is reduced. Antibodies are directed to the membranes of isolated human atrial myocytes and, to a lesser extent with lesser specificity, to endothelial cells and to the extracellular matrix. AMLAs are of diagnostic relevance if they belong to the IgM class, indicating a recent humoral immune stimulation and, if they fix complement, indicating a functional property which is complement associated lysis of target cells. Immunohistological studies demonstrate fixation of immunoglobulins to the autologous biopsy specimens, which are diagnostic only if they also belong to the IgM class and fix complement. In acute rhythm disturbances in the context of a recent "common cold", similar humoral immune reactions can be found in children, which are compatible with a secondary immunopathogenesis after viral illness involving the myocardium.
Adult↗
Double-blind placebo-controlled study of loratadine, mequitazine, and placebo in the symptomatic treatment of seasonal allergic rhinitis.
Loratadine is a long-acting H1 antagonist devoid of anticholinergic and sedative effects. A double-blind, placebo-controlled, parallel-group study was performed in 69 patients to compare efficacy and safety of loratadine and mequitazine. Patients allergic to grass pollens were randomly assigned to one of the three treatment groups and followed up to 2 weeks during the peak of the pollen season. Symptoms of allergic rhinitis were evaluated at baseline and after 3, 7, and 14 days of treatment by the physician with patients rating their response daily on diary cards. Both loratadine and mequitazine induced a significant relief of nasal symptoms when these were compared to placebo. Loratadine was found to be significantly superior to placebo after 3 days of treatment, whereas a significant improvement was only observed after 7 days in patients treated with mequitazine. For nonnasal symptoms, none of the two anti-H1 antagonist induced a significant improvement, and this lack of effect may be related to low symptoms at baseline. Loratadine did not induce more side effects than placebo. Loratadine can be considered to be an effective and safe anti H1 histamine with a rapid onset of action.
Adolescent↗