Expression and regulation of c-kit receptor and response to stem cell factor in childhood malignant T-lymphoblastic cells

The cytokine stem cell factor (SCF) synergizes with IL-7 to enhance the proliferation of thymocytes. We therefore investigated the role of the SCF receptor, the protooncogene c-kit, in the pathogenesis of pediatric T-lineage malignancies. Expression and regulation of c-kit in cells from children with non-Hodgkin's lymphoma (T-NHL) or acute lymphoblastic leukemia (T-ALL) and the proliferative effect of SCF on these cells were examined in seven cell lines and 21 biopsy tumor cell preparations. Inducibility of c-kit receptors by SCF, IL-1beta, IL-2, IL-7, TGF-beta, TNF-alpha, PMA or calcium ionophore A23187 was studied by flow cytometry (FCM). C-kit receptors were detected in three out of seven T-lymphoblastic cell lines and in nine out of 21 biopsy tumor cell preparations. Upregulation of c-kit could be induced by cultivation, and to a higher extent by cultivation and addition of IL-1beta, TNF-alpha, TGF-beta or A23187. Downregulation of c-kit occurred in the presence of SCF or PMA. SCF caused a downregulation of c-kit receptors in eight of nine, and a proliferative response in three of 11 c-kit-positive T-lymphoblastic cell preparations. We conclude that c-kit is able to transduce a growth stimulatory signal in some T-lymphoblastic cells and that its expression may not be detectable in a resting metabolic or proliferative state.     

Lipid peroxidation and changes in cytochrome c oxidase and xanthine oxidase activity in organophosphorus anticholinesterase induced myopathy

The data gained from clinical studies in the past years have indicated that the thrombolytic therapy (TL) has favourable effect on patients with acute myocardial infarction (AMI). It is aimed at reperfusion in the ischaemic area, a decrease in the extent of infarction site and a decrease in mortality. TL administered within the initial hours after the onset of AMI leads to better results than when administered after several hours. Currently, TL is not limited by age. The patients who were given streptokinase (SK) or anistreplase (APSAC) prior to more than 4 days, if necessary, urokinase or alteplase (rt-PA) should be given. There are differences in the opinions as to the optimal selection of thrombolytic drugs. However, all currently used drugs lead to a significant decrease in mortality due to AMI. The preferential use of accelerated administration of rt-PA in contrast to SK is justified in younger patients with extensive AMI of the anterior wall, in whom the therapy has begun within 4 hours since its onset. The occurrence of severe bleeding indicates that TL should be halted and coagulation factors should be replaced by freshly frozen plasma or fibrinogen concentrate, if necessary, transfusion of full blood should take place. If the severe bleeding occurs shortly after the administration of SK, the persisting plasminaemia can be arranged by antifibrinolytic drugs. An improvement in TL results can be achieved by adjuvant antithrombotic therapy. At the same time, in addition to acetylsalicylic acid, the patient treated with rt-PA should be given heparin. Heparin administration is not necessary in patients treated with SK or APSAC. However, heparin is indicated in patients at risk due to systemic embolization in congestive heart disease, extensive infarction or atrial fibrillation. (Tab. 1, Ref. 28.)     

Understanding the relationship between relative and absolute risk

BACKGROUND: Relative risks are the most common statistics used to quantify the risk of mortal or morbid outcomes associated with different patient groups and therapeutic interventions. However, absolute risks are of greater value of both patient and physician in making clinical decisions. METHODS: The relationship between relative and absolute risks is explained using graphical aids. A program to estimate absolute risks from relative risks is available on the internet (see ftp://ftp.vanderbilt.edu/pub/biostat/absrisk+ ++.txt). This program uses a competing hazards model of morbidity and mortality to derive these estimates. RESULTS: When a patient's absolute risk is low, it can be approximated by multiplying her relative risk by the absolute risk in the reference population. This approximation fails for higher absolute risks. The relationship between relative and absolute risk can vary dramatically for different diseases. This is illustrated by breast cancer morbidity and cardiovascular mortality in American women. The accuracy of absolute risk estimates will be affected by the accuracy of relative risk estimates, by the appropriateness of the reference groups used to calculate relative risks, by the stability of cross-sectional, age-specific morbidity and mortality rates over time, by the influence of individual risk factors on multiple causes of mortality, and by the extent to which relative risks may vary over time. CONCLUSIONS: Valid absolute risk estimates are valuable when making treatment decisions. They can often be obtained over time intervals of 10 to 20 years when the corresponding relative risk estimates have been accurately determined.     

Hepatitis C infection risk analysis: who should be screened? Comparison of multiple screening strategies based on the National Hepatitis Surveillance Program

Children with cerebral palsy (CP) display postural problems, largely interfering with daily life activities. Clarification of neural mechanisms controlling posture in these children could serve as a base for more successful intervention. Studies on postural adjustments following horizontal forward and backward displacements of a movable platform in ten school-age children with spastic diplegia and non-disabled controls revealed that sitting CP children, like standing CP children, show direction specific postural adjustments, indicating that the basic pattern of muscle coordination in these conditions is conserved. Dysfunctions are especially present in the modulation of the response pattern of ventral muscles during forward translations. They consist of: (1) a stereotyped and non-variable activation of all ventral muscles; (2) an abnormal top-down muscle recruitment; and (3) an excessive degree of antagonistic co-activation. The altered patterns of muscle coordination could be the result of two interacting mechanisms, the primary deficit due to the early brain damage and a compensation due to the postural instability. Especially the latter dysfunction furnishes opportunities for therapeutic help.     

A comparison of thrombolytic therapy with primary coronary angioplasty for acute myocardial infarction. Myocardial Infarction Triage and Intervention Investigators

BACKGROUND: Several relatively small randomized trials have shown that primary angioplasty results in a better short-term outcome than thrombolytic therapy in patients with acute myocardial infarction. These results, however, have not been duplicated other than in investigational trials. METHODS: We compared mortality during hospitalization and long-term mortality, as well as the use of resources, among 1050 patients in a primary-angioplasty group and 2095 patients in a thrombolytic-therapy group. Patients were selected from the Myocardial Infarction Triage and Intervention Project Registry cohort of 12,331 consecutive patients admitted with acute myocardial infarction to 19 Seattle hospitals between 1988 and 1994. Because of the potential for selection bias, several subgroup analyses were performed that included patients eligible for thrombolysis, high-risk patients, and patients in the primary-angioplasty group who were treated at hospitals with high volumes of angioplasty. RESULTS: There was no significant difference in mortality during hospitalization or long-term follow-up between patients in the thrombolytic-therapy group and those in the primary-angioplasty group (mortality during hospitalization, 5.6 percent and 5.5 percent, respectively; P=0.93; adjusted hazard ratio for the risk of death within three years after primary angioplasty, 0.95; 95 percent confidence interval, 0.8 to 1.2). There was also no significant difference in mortality between high-risk subgroups of patients in the two treatment groups. The rates of procedures and costs were lower among patients in the thrombolytic-therapy group both at the time of hospital discharge and after three years of follow-up (30 percent fewer coronary angiograms, 15 percent fewer coronary angioplasties, and 13 percent lower costs after three years of follow-up). CONCLUSIONS: In a community setting, we observed no benefit in terms of either mortality or the use of resources with a strategy of primary angioplasty rather than thrombolytic therapy in a large cohort of patients with acute myocardial infarction.     

Palmoplantar keratoderma associated with congenital heart disease

We report the case of a 14-month-old boy suffering from total anomalous pulmonary venous connection (TAPVC) associated with congenital diffuse palmoplantar keratoderma (PPK). An association between TAPVC and PPK has not been described previously, but PPK has been reported in association with a variety of cardiac abnormalities. Given the low frequency of both conditions, a genetic link seems likely. It is therefore advisable for dermatologists to check for heart abnormalities in children with congenital PPK.     

Passive transfer of Lambert-Eaton myasthenic syndrome induces dihydropyridine sensitivity of ICa in mouse motor nerve terminals

Mice were injected for 30 days with plasma from three patients with Lambert-Eaton Myasthenic Syndrome (LEMS). Recordings were made from the perineurial sheath of motor axon terminals of triangularis sterni muscle preparations. The objective was to characterize pharmacologically the identity of kinetically distinct, defined potential changes associated with motor nerve terminal Ca2+ currents (ICa) that were affected by LEMS autoantibodies. ICa elicited at 0.01 Hz were significantly reduced in amplitude by approximately 35% of control in LEMS-treated nerve terminals. During 10-Hz stimulation, ICa amplitude was unchanged in LEMS-treated motor nerve terminals, but was depressed in control. During 20- or 100-Hz trains, facilitation of ICa occurred in LEMS-treated nerve terminals whereas in control, no facilitation occurred during the trains at 20 Hz and marked depression occurred at 100 Hz. Saturation for amplitude and duration of ICa in control terminals occurred at 2 and 4-6 mM extracellular Ca2+, respectively; in LEMS-treated terminals, the extracellular Ca2+ concentration had to increase by two to three times of control to cause saturation. Amplitude of the two components of ICa observed when the preparation was exposed to 50 microM 3,4-diaminopyridine and 1 mM tetraethylammonium were both reduced by LEMS plasma treatment. The fast component (ICa,s) was reduced by 35%, whereas the slow component (ICa, s) was reduced by 37%. omega-Agatoxin IVA (omega-Aga-IVA; 0.15 microM) and omega-conotoxin-MVIIC (omega-CTx-MVIIC; 5 microM) completely blocked ICa in control motor nerve terminals. The same concentrations of toxins were 20-30% less effective in blocking ICa in LEMS-treated terminals. The residual ICa remaining after treatment with omega-Aga-IVA or omega-CTx-MVIIC was blocked by 10 microM nifedipine and 10 microM Cd2+. Thus LEMS plasma appears to downregulate omega-Aga-IVA-sensitive (P-type) and/or omega-CTx-MVIIC-sensitive (Q-type) Ca2+ channels in murine motor nerve terminals, whereas dihydropyridine (DHP)-sensitive (L-type) Ca2+ channels are unmasked in these terminals. Acute exposure (90 min) of rat forebrain synaptosomes to LEMS immunoglobulins (Igs; 4 mg/ml) did not alter the binding of [3H]-nitrendipine or [125I]-omega-conotoxin-GVIA (-omega-CgTx GVIA) when compared with synaptosomes incubated with an equivalent concentration of control Igs. Conversely, LEMS Igs significantly decreased the Bmax for [3H]-verapamil to approximately 45% of control. The apparent affinity of verapamil (KD) for the remaining receptors was not significantly altered. Thus acute exposure of isolated central nerve terminals to LEMS Igs does not increase DHP sensitivity, whereas it reduces the number of binding sites for verapamil but not for nitrendipine or omega-CgTx-GVIA. These results suggest that chronic but not acute exposure to LEMS Igs either upregulates or unmasks DHP-sensitive Ca2+ channels in motor nerve endings.     

Immunological and molecular characterization of three variant subtype P1.14 strains of Neisseria meningitidis

Epidemic outbreaks of group B meningococcal disease exhibit a clonal nature consisting of a common serotype-subtype. Subtype-specific monoclonal antibodies (MAbs) directed toward two variable regions (VR1 and VR2) of the class 1 protein of Neisseria meningitidis are used in this classification scheme. A new MAb was developed to classify a nonsubtypeable (NST) strain of N. meningitidis, 7967. This MAb bound to both the NST strain and the prototype subtype P1. 14 strain, S3446, by dot blot analysis. However, a MAb produced to the prototype P1.14 strain did not bind to strain 7967. Sixteen additional strains were further identified as P1.14 with the prototype MAb; of these, 15 strains bound both MAbs. Differences in the characteristics of binding of both antibodies to the three apparently diverse P1.14 strains were studied further by using outer membrane complex proteins, immobilized peptides, and soluble peptides. Deduced amino acid analysis suggested that both MAbs bind to VR2 and that single amino acid changes within VR2 (KM, NM, or KK) might explain the differences in binding characteristics. These results demonstrated that minor variations which exist within subtype variable regions may be clearly identified only by a combination of molecular and immunologic testing. The impact of subtype variation will become more evident as subtype-specific vaccines are developed and tested for efficacy.     

In situ localization and quantification of mRNA for 92-kD type IV collagenase and its inhibitor in aneurysmal, occlusive, and normal aorta

Ninety-two-kilodalton type IV collagenase (MMP-9) is present in aortic aneurysms and may be important to the pathogenesis of this disease. Alteration in expression of MMP-9 or its inhibitor, the tissue inhibitor of metalloproteinase type 1 (TIMP-1), could increase degradation of extracellular matrix and lead to aneurysm formation. The purpose of this study was (1) to measure tissue levels of MMP-9 and TIMP-1 mRNA in aneurysmal (AAA), atherosclerotic occlusive (AOD), and normal (NL) human infrarenal aorta; (2) to test for their expression by cultured AAA and NL vascular smooth muscle cells (VSMCs); and (3) to locate in situ the cells responsible for mRNA production within AAA, AOD, and NL aortic wall. Total RNA extracted from AAA (n = 8), AOD (n = 8), and NL (n = 7) tissue was subjected to Northern analysis. Signals for MMP-9 and TIMP-1 were normalized to alpha-tubulin. Mean values +/- SEM were compared by ANOVA. NL and AAA VSMCs were cultured, passaged, and grown to confluence before RNA extraction and Northern analysis. In situ hybridization with digoxigenin-labeled RNA probes localized cells responsible for MMP-9 and TIMP-1 mRNA expression within sections of AAA (n = 5), AOD (n = 2), and NL (n = 2) aorta. MMP-9 mRNA levels were significantly greater in AAA (0.855 +/- 0.180) than NL (0.046 +/- 0.23) (P < .02), but differences between AOD (0.406 +/- 0.196) and AAA or AOD and NL were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)     

Increased expression of complement component C3 in the plasma of obese Zucker fa and LA/N fa(f) rats compared with their lean counterparts

OBJECTIVES: The objectives of this study were to determine whether there are differences in the electrophoretic profiles of plasma proteins from lean and obese rats and to identify a protein that was found to be more abundant in the plasma of obese rats. RESEARCH METHODS AND PROCEDURES: Plasma proteins from lean and obese Zucker fa and LA/N fa(f) rats were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The identity of a band that was differentially expressed was determined by amino acid sequencing and Western blot analysis. RESULTS: A band migrating approximately the same distance as the 116 kDa molecular weight marker was more prominent in plasma from obese rats than in plasma of lean rats. Partial sequencing of the peptide revealed that 17 of the first 18 amino acids at the amino terminus were identical with the corresponding residues in the alpha-chain of complement component C3. Western blot analysis confirmed the identity of the peptide as complement component C3. Complement C3 activity was measured using a hemolytic assay to determine whether there was a corresponding increase in the biological activity of this component in the serum of obese rats. Serum from obese rats was found to have 1.8 times as much complement component C3 activity as serum from lean rats. DISCUSSION: Elevated levels of complement C3 in genetically obese rats may be relevant because increased amounts of C3 could serve as a reservoir from which increased amounts of acylation stimulating protein, a cleavage product of complement C3, could be produced.