Biomedical subjects
Publications and source records attributed to J Blake.
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Crosslinking of sIgM on the B cell line WEHI 231 with anti-sIgM antibody induces protein tyrosine phosphorylation, implicating protein tyrosine kinases (PTKs) in sIg-mediated signal transduction. We have analyzed this cell line for members of the src family of PTKs and have evaluated whether these PTKs might be involved in the process of sIgM-mediated signaling. Our results show that Blk, Lyn, Lck, and Hck are detectable in WEHI 231 cells. Addition of antibodies to sIgM were found to variably stimulate the activities of Blk, Lyn, Lck, and Hck as measured by immune-complex protein kinase assays. Autophosphorylation of these src PTKs, as assessed by reaction with anti-phosphotyrosine antibodies, increased over the time course of sIgM-mediated activation. Co-immunoprecipitation studies to investigate the potential physical interaction of src PTKs with the sIgM receptor complex revealed that, under digitonin and Brij 96 lysis conditions Lyn, Lck, Hck, but not Blk associated with sIgM.
Activation of T cells through the TCR/CD3 receptor complex with either specific Ag or antibody results in tyrosine phosphorylation of intracellular protein substrates and phosphatidylinositol-phospholipase C (PLC) signaling, leading to the generation of PI breakdown products and the mobilization of intracellular calcium. Stimulation of the T cell surface receptor CD2 similarly propagates early signals through phosphatidylinositol-PLC activation. Previous reports have shown that CD3 activation leads to tyrosine phosphorylation of the PLC isozyme PLC gamma 1. In this report, we investigated the potential similarity between CD3-induced signaling through PLC gamma 1 and that induced by CD2. We show that stimulation of CD2 receptors on T cells caused tyrosine phosphorylation of PLC gamma 1. Cross-linking of CD2 with CD3 receptors augmented the phosphorylation of PLC gamma 1 on tyrosine, whereas ligation of the CD45 tyrosine phosphatase with CD2 receptors prevented PLC gamma 1 tyrosine phosphorylation. T cells stimulated by ligation of CD2 with its counter-receptor in the form of a soluble LFA-3/Ig fusion protein cross-linked on the cell surface, resulted in a low, but detectable level of PLC gamma 1 phosphorylation with prolonged kinetics, whereas that induced by cross-linking with anti-CD2 was stronger but transient. Co-ligation of LFA-3/Ig with suboptimal concentrations of anti-CD3 resulted in profound augmentation of PLC gamma 1 tyrosine phosphorylation, mobilization of intracellular calcium and T cell proliferation. To explore the relationship between CD3- and CD2-stimulated signaling, T cells were desensitized through 1 h incubation with anti-CD3. CD3 receptor modulation potently down-regulated CD2-induced PLC gamma 1 tyrosine phosphorylation and calcium mobilization. In contrast, PMA or ionomycin treatment did not alter CD2-stimulated tyrosine phosphorylation of PLC gamma 1, suggesting that tyrosine kinase inhibition by CD3 receptor modulation was not caused by signaling events downstream of PLC gamma 1. Taken together, these results support the hypothesis that CD2 provides a potent co-stimulatory signal for CD3-induced T cell activation that is associated with tyrosine kinase(s) and PLC gamma 1.
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Three Canadian-English infants and three Parisian-French infants were filmed bi-weekly for three to five months, from the age of 0;9 or 0;11 until 1;2, at home in naturalistic interaction with a parent. Their babbled utterances were transcribed phonetically and categorized according to consonant-type and vowel-type. The contexts for each utterance were described in terms of both specific and more general contextual categories. Observed frequencies of co-occurrences between phonetic and contextual categories were compared to expected frequencies, and deviations were considered to be patterns in babbling. Patterning increased after age 1;0 for most infants, and from 1% to 30% of each infant's babbled utterances recurred in particular contexts with a greater-than-expected frequency. Similarities in patterns were found both within and across language groups. These sound-meaning correspondences in babbling are viewed as continuous with early situation-bound meaning in words.
During the solid-phase synthesis of over 100 peptides, we have observed that the ethylcarbamoyl group is useful for the side chain protection of cysteine in peptides containing a single cysteine residue. The ethylcarbamoyl group is stable to the conditions of acidolytic cleavage, purification and long term storage. Brief treatment of peptides containing an S-ethylcarbamoyl-cysteine residue with aqueous sodium hydroxide gives the deprotected cysteine peptide that can be coupled to carrier molecules such as proteins to give immunogen conjugates.
A peptide (C13) corresponding to the last 13 amino acids of the carboxyl terminus of human platelet factor IV was found to be antibacterial. Amino acid substitutions predicted to disrupt either the amphipathic or alpha-helical nature of C13 rendered the peptide inactive. Antibacterial activity was demonstrated in normal human serum on bacteria which had been previously exposed to low levels of cefepime, a beta-lactam antibiotic. Peptide analogues were examined for more potent antibacterial activity in an antibacterial assay that employed normal human serum and low levels of cefepime. A peptide analogue (C18G) with 80-fold more antibacterial activity than C13 was identified. Studies in C8-deficient sera confirmed an essential role of human serum complement for optimal antibacterial activity. Additional studies showed low levels of cefepime, although not essential, enhanced the antibacterial activity of C18G. Animal protection experiments demonstrated that either peptide C18G or an analogue with all D amino acids (C18X) significantly increased the survival of neutropenic mice when coadministered with a low level of cefepime. This work has resulted in the identification of a new group of antibacterial peptides.
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The gynecologic examination of the child or adolescent need not be trying to the patient or the physician. Patience, awareness of the patient's need to be treated with respect and honesty, and knowledge of a few modifications to the adult technique will allow a helpful examination in almost all cases. The final objective should always be to promote the gynecologic health of the patient, and this is best accomplished if she leaves the physician's office with a positive reinforcement of her self-esteem, and her ability to participate in her own health care.
The ability of magainin 2 to augment antibiotic therapy was examined. Susceptibility to magainin 2 was determined on Escherichia coli incubated in the presence and absence of sublethal concentrations of antibiotics both in vitro and in vivo. Experiments in buffer and normal human serum revealed that E. coli exposed to sublethal amounts of cefepime, a beta-lactam antibiotic, was significantly more susceptible to the antimicrobial activity of magainin 2. Bacteria incubated with subinhibitory concentrations of other beta-lactam type antibiotics, but not amikacin (an aminoglycoside) or ciprofloxacin (a quinolone), were also more susceptible to magainin 2 in normal human serum. Bacteria were less susceptible to magainin 2 when they were examined in heat-inactivated serum. Complement was shown to be required for magainin 2 activity in serum by using C8-deficient sera. The combination of magainin 2 and cefepime was shown to be more antimicrobial in normal human serum for a variety of bacterial strains. Magainin 2 was completely inactive as a therapeutic agent when it was administered alone (2 mg per mouse) but significantly increased the survival of mice when it was administered with a low level of cefepime.
Analysis of cDNA clones encoding transforming growth factor (TGF)-beta 2 predicts two different precursor proteins derived by alternative mRNA splicing; a 414 amino acid precursor [TGF-beta 2(414)] and a 442 amino acid precursor [TGF-beta 2(442)]. The two proteins differ by a 28 amino acid insertion within the pro-region of TGF-beta 2(442). In order to characterize the TGF-beta 2-related proteins encoded by the TGF-beta 2(442) cDNA and determine whether it could, in fact, direct the synthesis of active growth factor, we have expressed this gene in Chinese hamster ovary (CHO) cells and, after amplification with methotrexate, obtained stable clones secreting TGF-beta 2(442). The TGF-beta 2 secreted by these cells was latent as acidification was necessary to detect optimal biological activity. In addition to mature TGF-beta 2, high molecular weight pro-region containing proteins were also secreted as analyzed by immunoblotting using site-specific anti-peptide antibodies. These proteins migrated differently than those secreted by CHO cells transfected with cDNA encoding TGF-beta 2(414), indicating that structural differences exist between the two complexes. An anti-peptide antiserum was produced in rabbits against the 28 amino acid insert region of TGF-beta 2(442). This sera was then used to detect the presence of TGF-beta 2(442) in serum-free media conditioned by BSC-40 cells. Since the TGF-beta 2(442) precursor is produced and secreted by a non-recombinant cell line, this suggests that it may play a physiological role in regulating the activity of TGF-beta 2.
Monitoring the effectiveness of treatment sfor alcoholic liver disease involves the use of variables that have prognostic significance and are unaffected by the treatment in unspecific ways. Here we review the value of histological and functional variables for this purpose. We conclude that histological variables, although important in defining the characteristics of the sample, have several practical problems. The functional variables are most effective when used in combinations, e.g., in global indices such as the Combined Clinical and Laboratory Index, the Child-Turcotte-Pugh Index, or the Cox model. In situations involving mortality and dropouts, functional indices cannot be used to measure changes in severity; in such cases, mortality might be the only measure for assessing the effectiveness of a treatment. In clinical trials, it is essential to determine the risk of a Type II error, to monitor compliance and drinking, and to trace appropriately all the patients who were not compliant or who dropped out of the trial.
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PURPOSE: To elucidate determinants of abnormal left ventricular functional responses to exercise in hypertensive patients. PATIENTS AND METHODS: One hundred twenty-seven patients with uncomplicated essential hypertension were studied by rest and exercise radionuclide angiography and by echocardiography at rest. RESULTS: The 24 patients with subnormal left ventricular ejection fraction at peak exercise (less than 54%) were similar in age and rest and exercise blood pressures to the 103 with normal exercise ejection fraction, but were more obese (p less than 0.005) and had greater left ventricular mass (p less than 0.03) and internal dimensions (p less than 0.001). The parallel increase in left ventricular chamber size and mass (eccentric hypertrophy) in the group of patients with exercise dysfunction was associated with higher resting end-systolic wall stress (p less than 0.001) and abnormal increases of end-systolic left ventricular volume from rest to peak exercise (p less than 0.001). Multivariate analysis revealed that exercise left ventricular dysfunction was independently associated with higher left ventricular mass (p less than 0.0005), end-systolic wall stress (p less than 0.001), dietary sodium intake (p less than 0.01), and body mass index (p less than 0.03). CONCLUSION: Among patients with uncomplicated essential hypertension, abnormal functional responses to exercise are strongly associated with eccentric ventricular hypertrophy, obesity, and high sodium intake.
The U.S. Environmental Protection Agency sampled air in 49 government-owned buildings (six buildings with no asbestos-containing material, six buildings with asbestos-containing material in generally good condition, and 37 buildings with damaged asbestos-containing material). This is the most comprehensive study to date of airborne asbestos levels in U.S. public buildings during normal building activities. The air outside each building was also sampled. Air samples were analyzed by transmission electron microscopy using a direct transfer preparation technique. The results show an increasing trend in average airborne asbestos levels; outdoor levels are lowest and levels in buildings with damaged asbestos-containing material are highest. However, the measured levels and the differences between indoors and outdoors and between building categories are small in absolute magnitude. Comparable studies from Canada and the UK, although differing in their estimated concentrations, also conclude that while airborne asbestos levels may be elevated in buildings that contain asbestos, levels are generally low. This conclusion does not eliminate the possibility of higher airborne asbestos levels during maintenance or renovation that disturbs the asbestos-containing material.
Retrobulbar block for eye surgery is associated with adverse reactions. We performed retrobulbar block in 10 patients using prilocaine (Citanest) and found mean (SD) peak serum concentrations of 851 (165.6) ng ml-1 (range 540-1100 mg ml-1). Peak serum concentrations occurred 3-7 min after the end of administration of the block, and in all cases were less than those associated with toxicity.
Family background continues to be closely related to individuals' educational attainment in the United States. A notable change in one aspect of this background, number of siblings, is occurring as fertility is becoming extremely low. Examination of the negative relation between individuals' sibling number and years of schooling indicates that education among those with many siblings is disproportionately cut short before high school graduation. Because there is a strong negative relation between number of siblings and scores on tests measuring verbal ability, recent reductions in sibling number would be expected to contribute to enhanced verbal ability and increasing years of schooling for those born now in the United States.
A patient with disseminated diffuse histiocytic lymphoma had persistent electrocardiographic (ECG) signs of acute myocardial infarction without clinical, enzymatic, or hemodynamic evidence of myocardial necrosis. The ECG findings were felt to be secondary to myocardial tumor invasion by antemortem noninvasive testing. This was confirmed by postmortem examination. Based on this report and a literature review, the particular ECG findings noted (lateral leads) are felt to be highly predictive of direct tumor invasion in this setting.