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L J Smith

Publications and source records attributed to L J Smith.

At least 19 recordsLinked to original sources
PubMed1992

Loop mobility in a four-helix-bundle protein: 15N NMR relaxation measurements on human interleukin-4.

15N NOE, T1, and T2 measurements have been carried out on uniformly 15N-labeled human interleukin-4. Analysis of the results in terms of order parameters (S2) shows that although the helical core of this four-helix-bundle protein exists as a well-defined structure with limited conformational flexibility (S2 congruent to 0.9), other regions of the molecule experience substantial fluctuations in the conformation of the main chain (S2 = 0.3-0.8). These regions include both the N- and C-termini and two of the loops joining the helices. The majority of these internal motions are fast compared with the overall rotational correlation time (tau R = 7.6 ns at 35 degrees C) and are localized in regions that are relatively ill-defined in the NMR structures previously determined for this protein [Smith, L. J., Redfield, C., Boyd, J., Lawrence, G. M. P., Edwards, R. G., Smith, R. A. G., & Dobson, C. M. (1992) J. Mol. Biol. 224, 899-904]. Other motions are on a slower time scale and appear to be associated with two of the three disulfide bonds and the beta-sheet region in the protein. The dynamic properties of interleukin-4 in solution have been compared with features of the X-ray structures of other four-helix-bundle proteins. The results suggest that the dynamic properties observed here may be general for this class of proteins and may be significant for the interpretation of both their structural and functional properties.

Humans↗
PubMed1992

Measurement of the secondary structure of adsorbed protein by circular dichroism. 1. Measurements of the helix content of adsorbed melittin.

A new circular dichroism (CD) technique is presented which quantifies, in situ, the changes in protein and peptide secondary structure upon adsorption at the quartz/liquid interface. Far-UV CD spectra of adsorbed proteins were recorded from several quartz interfaces contained in a specially constructed cell. Adsorbed, oriented alpha-helical spectra were recorded from hydrophilic and hydrophobic quartz using the bee venom peptide, melittin, which can be induced into an alpha-helical, tetrameric conformation in solution. The hydrophobic quartz provides a model system for oil-in-water emulsions and cell membranes. Surface concentrations were determined by radio-counting and were dependent on the nature of the surface. The characterization of these spectra has been partly achieved using far-UV CD spectra obtained from melittin adsorbed onto hydrophilic colloidal silica particles, where orientation effects are eliminated. Analysis of these spectra reveals considerable denaturation of the helical structures upon adsorption. Surface concentrations from the silica were determined from adsorption isotherms. The surface orientation of adsorbed melittin was dependent on the state of aggregation and hence degree of helicity of the molecule. These results support a model for the mode of action of melittin in lysing membranes.

Adsorption↗
PubMed1992

Secondary structures of a new class of lipid body proteins from oilseeds.

The three main isoforms of the 19-kDa lipid body proteins (oleosin) have been purified to homogeneity from embryos of rapeseed. The secondary structures of these proteins as derived from circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopy were compared with the secondary structures predicted from the primary sequences. The salient feature of the primary sequence of all oleosins is its division into three defined structural domains: a central hydrophobic domain flanked on either side by relatively hydrophilic domains, respectively. Using a variety of predictive methods based on primary amino acid sequence data, the oleosins exhibited a high probability of beta-strand structure in the 70-residue central hydrophobic domain, with relatively little alpha-helical content. Secondary structure data derived from CD and FTIR were consistent with the predictions from primary sequence, showing that the oleosins contained about 45% beta-strand and 13% alpha-helical structure. Under high salt conditions, a 40-kDa polypeptide was obtained from purified preparations of the 19-kDa oleosins. The 40-kDa polypeptide has a very similar secondary structure, as analyzed by CD and FTIR, to that of the 19-kDa oleosins. This polypeptide is therefore probably a dimer of the 19-kDa oleosins that is formed in high salt environments. A model of the general structure of oleosins is proposed whereby the central hydrophobic domain of the protein with a predominantly beta-strand structure is embedded into the non-aqueous phase of lipid-bodies. This hydrophobic region is flanked by putative alpha-helical structures in the polar N- and C-terminal domains which are probably oriented at the lipid-water interface.

Amino Acid Sequence↗
PubMed1992

Human interleukin 4. The solution structure of a four-helix bundle protein.

Heteronuclear 13C and 15N three-dimensional nuclear magnetic resonance (n.m.r.) techniques have been used to determine the solution structure of human interleukin 4, a four-helix bundle protein. A dynamical simulated annealing protocol was used to calculate an ensemble of structures from an n.m.r. data set of 1735 distance restraints, 101 phi angle restraints and 27 pairs of hydrogen bond restraints. The protein structure has a left-handed up-up-down-down topology for the four helices with the two long overhand loops in the structure being connected by a short section of irregular antiparallel beta-sheet. Analysis of the side-chains in the protein shows a clustering of hydrophobic residues, particularly leucines, in the core of the bundle with the side-chains of charged residues being located on the protein surface. The solution structure has been compared with a recent structure prediction for human interleukin 4 and with crystal structures of other helix bundle proteins.

Computer Graphics↗
PubMed1992

Infantile spasms.

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History, 19th Century↗
PubMed1992

Psychosocial adjustment of patients arriving early at the emergency department after acute myocardial infarction.

The psychosocial functioning of patients arriving at the emergency department with an acute myocardial infarction early enough to be candidates for treatment with thrombolytic agents was compared with that of those arriving later. Patients who arrived within 3 hours were significantly more anxious when assessed 1 week after admission and had a consistently worse pattern of psychosocial adjustment 3 months after hospital discharge than did those who arrived later. The implications of these findings for efforts to improve early arrival at the emergency department, as well as for medical and psychosocial outcomes after acute myocardial infarction, were considered.

Adult↗
PubMed1992

Effective education of adults with asthma who are allergic to dust mites.

The effects of supplementary computer instruction in house dust mite-avoidance measures on adherence to implementing measures, on home dust mite-allergen levels, and on symptomatology were investigated in 52 adult patients with mite-associated asthma. Twenty-six patients received conventional instruction (counseling and written instruction) and the other 26 patients received conventional plus 22 minutes of interactive computer-assisted instruction. Instructions were aimed at mite-avoidance measures. Pre- and postinstruction dust samples were collected, and adherence was monitored. All patients kept symptom diaries twice a day. Patients' progress was followed for 12 weeks, and all patients completed the study. Adherence, number of observed and self-reported mite-avoidance measures implemented after visit, was higher for the computer group (p = 0.023). The computer-instructed group achieved significantly lower levels of mite allergen in bedroom carpets (p = 0.004) with mean levels of mite allergen declining from 6.5 +/- 7.6 to 2.2 +/- 4.3 micrograms/gm of dust (two-site monoclonal antibody assays), whereas levels for the conventional-instructed group did not change. Moreover, by study weeks 9 and 10, the computer-instructed group was significantly less symptomatic (p = 0.033). Mean symptom scores for this group decreased from 12.4 to 7.7, compared with 16.4 to 14.3. Conventional instruction supplemented with computer instruction is suggested in mite education.

Adolescent↗
PubMed1992

Glutathione localization and distribution after intratracheal instillation. Implications for treatment.

To gain insight into how glutathione given directly into the lung protects fasted mice against hyperoxic lung damage and to provide a framework for developing treatment strategies in patients, we determined the lung distribution and retention of intratracheally administered glutathione (GSH) and its fate after leaving the lung. Mice received an intratracheal injection of [3H]GSH with or without cold GSH and with or without liposomes. The distribution of the 3H label was equal in both lungs, but the left lung had a higher concentration because of its smaller size. The 3H label was cleared rapidly from the lung: only 1% remained at 24 h, and more than 50% of the label at that time was no longer attached to the GSH. Administration of GSH with liposomes increased the retention of GSH by 20 to 50%, but the amount remaining at 24 h was still only 1%. The increase associated with the liposomes was due to enhanced retention of the GSH encapsulated in the liposomes, not the much larger amount present free in the GSH-liposome mixture. Fasting and exposure to 100% oxygen had little effect on GSH retention. Some of the 3H label leaving the lung was excreted by the kidneys, a small amount was retained in the liver, and a large amount accumulated in the blood. Of the amount in the blood, about 60% was in red blood cells (RBC) and the rest in plasma. Much of the 3H label in RBC and lung at 24 h was no longer attached to the GSH, whereas most in the plasma and liver was.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Oxygen-induced lung damage. Relationship to lung mitochondrial glutathione levels.

Several reports suggest there is a relationship between lung glutathione (GSH) levels and susceptibility to oxygen-induced lung damage. However, studies of other organs and cells indicate that a better relationship may exist between mitochondrial GSH levels and oxidant damage. We determined whether there is a similar relationship in the lung using a well-characterized mouse model and a series of interventions that alter lung GSH levels and susceptibility to oxygen-induced lung damage. Mice were fasted or given buthionine sulfoximine (BSO, 20 mM), which reduce total lung GSH levels and increase susceptibility to oxygen-induced lung damage. Mice were also given glutathione monoethyl ester (GSH-ME) intraperitoneally (5 or 10 mM/kg/day for 2 days) or intratracheally (0.2 mM once) in an attempt to increase lung GSH levels. Fasting for up to 3 days and the administration of BSO for 7 to 10 days decreased total lung GSH levels (p < 0.001 for both) but not lung mitochondrial GSH levels. Intraperitoneal administration of GSH-ME increased mitochondrial GSH levels (p < 0.001 in both fed and fasted mice), but it had little effect on total lung GSH levels and no effect on susceptibility to oxygen-induced lung damage. Exposure to 100% oxygen increased mitochondrial GSH levels in both the fed and fasted mice to nearly the same extent (p < 0.001 for both). However, the fasted mice had lower total lung GSH levels compared with the fed mice (p < 0.05) and increased susceptibility to 100% oxygen.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Sulfasalazine-induced pulmonary disease.

We report the findings in two patients with sulfasalazine-induced pulmonary disease. The first patient developed pulmonary interstitial fibrosis after more than 4 yr of treatment for Crohn's disease. Pulmonary symptoms and chest roentgenographic and pulmonary function abnormalities gradually reversed after stopping the drug. No specific treatment was given. The second patient, who had rheumatoid arthritis without pulmonary disease, received the drug for 1 yr without experiencing any problems. Readministration seven months later resulted in the development of an acute interstitial pulmonary disease. Discontinuing the drug and treatment with corticosteroids produced rapid improvement. We discuss these patients in relation to other reports of sulfasalazine-induced pulmonary toxicity, highlighting their atypical features.

Acute Disease↗
PubMed1992

Lung cancer in young adults.

OBJECTIVE: To define the basis for the conflicting reports on the prognosis of lung cancer in young adults. DESIGN: Retrospective review of lung cancer patients between 1977 and 1988. SETTING: Medical centers in Chicago (Northwestern Memorial Hospital), northern Israel (Rambam Medical Center), and northern Italy (S. Anna and U. of Pavia Hospitals). PATIENTS: Patients were < or = 45 years of age with a diagnosis of primary lung cancer identified from tumor registry records, pathology reports, and hospital charts, plus a sample of patients > 45 years of age. MEASUREMENTS AND MAIN RESULTS: In Chicago, younger patients had a higher incidence of chest pain, fever, and neurologic symptoms at presentation than the older patients, and fewer were asymptomatic. They also had more lower lobe lesions on chest roentgenogram, a higher incidence of adenocarcinoma, more advanced disease, an increased likelihood of receiving chemotherapy, and reduced survival (p < 0.03). The poorer prognosis was due to more advanced disease at presentation. In Israel, younger patients more frequently presented with stage I disease than the older patients and they had a higher incidence of adenocarcinoma, an increased likelihood of receiving treatment especially surgery, and better survival (p < 0.02). There were no differences between the two age groups for symptoms, symptom duration, and chest roentgenogram findings. Compared with the younger patients in Chicago and Israel, those from northern Italy had more squamous cell cancers and fewer adenocarcinomas, more commonly presented with stage I or II disease, received radiation therapy less frequently, and were given supportive care more often. Survival was low and comparable to that reported from Chicago. CONCLUSION: Differences exist in the clinical characteristics, pathologic findings, and prognosis of younger and older patients with lung cancer from the same region and of younger patients from different regions. The difference in prognosis is related in part to the stage of disease at presentation and the ability to undergo resectional surgery.

Adenocarcinoma↗
PubMed1992

Peritoneal dialysis in the critically ill patient.

The use of peritoneal dialysis on an acute basis is increasing each year. Peritoneal dialysis pulls waste products and excess water out of the blood stream and into dialysate solution in the peritoneal cavity. When patients are unstable hemodynamically, have severe cardiovascular disease, already require peritoneal dialysis, or are small children, peritoneal dialysis is the preferred treatment. Patients may be dialyzed using either a cycler or manual peritoneal dialysis. Patients should be monitored carefully for volume status, bowel status, and infection. Potential complications include problems with access, infection, pain, respiratory status, fluid imbalance, and potassium imbalance. Special consideration should be given to nutritional status because critically ill patients often need increased intake. Drug therapy needs modification because excretion of drugs by the kidney is delayed. Patient and family support is important because of decreased ability to understand, anxiety, loss of control, and change in body image. Treatment termination also may be an issue.

Critical Care↗
PubMed1992

Production of leukotrienes and thromboxane by resident and activated rat alveolar macrophages: a possible role of protein kinase C.

Arachidonic acid metabolism in resident rat alveolar macrophages and in those activated with complete Freund's adjuvant (CFA) was studied. Adult Sprague-Dawley rats were injected with 0.05 ml CFA, and macrophages were harvested 10 days later. Macrophages were labeled overnight with carbon 14-labeled arachidonic acid, washed, and then stimulated with calcium ionophore A23187 (IoA), phorbol myristate acetate (PMA), or zymosan for 30 minutes. Prostaglandins, thromboxane, and leukotrienes were extracted from the medium and analyzed by radioimmunoassay or radio high-pressure liquid chromatography. Cell lipids were analyzed by radio thin-layer chromatography. Medium and cell beta-glucuronidase activity and protein kinase C activity of the membrane fraction were also assayed. We found (1) lower leukotriene B4 (LTB4) production in stimulated resident macrophages when compared with resident macrophages after IoA stimulation--the suppressed LTB4 production was reversed by PMA; (2) unchanged or higher LTB4 production in activated macrophages when compared with resident macrophages after zymosan stimulation; (3) inhibition of zymosan-stimulated LTB4 production by staurosporine, a protein kinase C inhibitor, in both groups; and (4) lower diacylglycerol (DAG) production in activated macrophages when compared with resident macrophages after IoA stimulation, but not after zymosan stimulation. These results suggest that the reduced response of activated macrophages to IoA is due to decreased production of an endogenous protein kinase C activator. This hypothesis was further supported by the observation that protein kinase C activation in response to IoA was lower in activated macrophages than in resident macrophages. In contrast, zymosan stimulation resulted in higher protein kinase C activation in activated macrophages when compared with resident cells. We hypothesize that protein kinase activation is necessary for leukotriene production and that the preserved ability of zymosan to activate PKC via DAG accounts for the high leukotriene production in zymosan-activated macrophages. We also found that stimulated thromboxane production was higher in activated than resident cells, regardless of the stimulus, and that thromboxane production was not affected by staurosporine. Thus alterations of eicosanoid metabolism in immunologically activated macrophages depend on the stimulus used and the type of eicosanoid examined. Furthermore, leukotriene biosynthesis in rat alveolar macrophages may be regulated by protein kinase C.

Animals↗
PubMed1991

Secondary structure and topology of human interleukin 4 in solution.

Human interleukin 4 (IL-4) has been studied by 2D and 3D NMR techniques using uniformly 15N-labeled recombinant protein. Assignment of resonances for all but 3 of the 130 residues of the recombinant protein has been achieved, enabling the secondary structure of the protein to be defined. This consists of four major alpha-helical regions and one short section of double-stranded antiparallel beta-sheet. Analysis of distance and angle restraints derived from NMR experiments has enabled the overall molecular topology to be determined. This is related to that found for other four-helix proteins but has several distinctive features including cross-linking of helices by means of three disulfide bonds and a short section of beta-sheet. The structural analysis gives support to the hypothesis that many helical cytokines have a common fold and provides a basis for understanding the biological function of IL-4.

Amino Acid Sequence↗