Conformational studies on human transferrin.
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Apoproteins↗
Biomedical subjects
D Chapman
Publications and source records attributed to D Chapman.
FAMTX versus etoposide, doxorubicin, and cisplatin: a random assignment trial in gastric cancer.
PURPOSE: The chemotherapy regimens of high-dose methotrexate, high-dose fluorouracil (FU), Adriamycin (doxorubicin; Adria Laboratories, Columbus, OH), and leucovorin (FAMTX) and etoposide, Adriamycin, and cisplatin (EAP) have both been reported in nonrandom assignment trials to have high overall response rates and substantial complete response rates in patients with gastric cancer, as well as major toxicities of myelosuppression. Here we report a prospective, stratified, random-assignment comparison of the two combinations in previously untreated patients with advanced gastric cancer. PATIENTS AND METHODS: Sixty patients were entered onto the trial, 30 receiving EAP and 30 FAMTX. All patients had measurable or assessable tumor masses. Patient entry was stopped at the point when significant toxicity differences were seen at interim analysis. RESULTS: Response rates were similar between the two arms (FAMTX, 33% [95% confidence interval (CI), 16% to 50%]; EAP, 20% [95% Cl, 6% to 34%]). Three FAMTX and no EAP patients had complete remissions. The median survival for the two arms were similar (EAP, 6.1 months; FAMTX, 7.3 months). At 1 year, 7% of EAP and 17% of FAMTX patients were alive. EAP caused significantly more myelosuppression (leukopenia, P = .002; anemia, P = .03; thrombocytopenia, P = .0001) than did FAMTX. EAP also resulted in significantly longer hospitalizations per study month (8 v 5 days). Four EAP patients died of lethal toxicity, whereas no FAMTX patients died of treatment-related causes (P = .04). CONCLUSIONS: FAMTX is at least as active as EAP and is significantly less toxic. Although both regimens remain investigational, the toxicities of FAMTX are more manageable. Further studies involving FAMTX in both the adjuvant and advanced disease setting are underway.
Adult↗
Protein depletion and metabolic stress in elderly patients who have a fracture of the hip.
A prospective study was performed to determine the effect of protein depletion and postoperative nutritional status on the outcome in sixty-three elderly patients who had been admitted to the hospital because of a fracture of the hip. The parameters that were used to determine the degree of protein depletion included levels of albumin, of prealbumin, and of transferrin; total lymphocyte count; and nitrogen-balance studies. The outcomes that were examined were the development of complications, the length of the stay in the hospital, the ability to return to the pre-fracture level of function, and over-all survivorship. The hypothesis was that the acute fracture and the subsequent operation are severe stresses in these elderly, often compromised patients. The results supported the hypothesis. Thirty-seven patients (58 per cent) in the study group were in a protein-depleted state during the period of hospitalization. The patients who were protein-depleted had a higher prevalence of complications, were less likely to return to their pre-fracture environment, and tended to stay in the hospital longer, as compared with the nonprotein-depleted patients. Survivorship analysis showed that protein-depleted patients had a significantly lower probability of survival one year after the fracture of the hip (p = 0.02). Elderly patients who sustain the trauma of a fracture of the hip should be managed appropriately with regard to intake of nutrients in the postoperative period.
Aged↗
Fourier transform infrared spectroscopic studies of Ca(2+)-binding proteins.
The secondary structures of calmodulin and parvalbumin are well established from X-ray diffraction and nuclear magnetic resonance spectroscopic studies, which indicate that these proteins are predominantly alpha-helical in character. Recent infrared studies have nevertheless suggested that the helical structures present in these proteins in solution are not the standard alpha-helix but rather some kind of distorted helices [Trewhella, J., et al. (1989) Biochemistry 28, 1294]. The evidence for this was the unusually low amide I frequency for calmodulin and troponin C in 2H2O solution. The studies presented here, however, suggest that the helical structures in these proteins are not significantly distorted, for two reasons. First, distorted helical structures have weaker hydrogen bonds than the standard alpha-helix and would therefore be expected to absorb at a higher rather than a lower frequency. Second, distorted helical structures would absorb at an unusual frequency in H2O solutions which is not the case for the proteins studied here. The band frequency of these proteins is observed to occur at a frequency observed with other proteins known to contain predominantly alpha-helical structures. Quantitative analysis of the FT-IR spectra of calmodulin (67% alpha-helix) and parvalbumin (68% alpha-helix) in H2O in the presence of Ca2+ gives helical contents similar to those reported by X-ray studies. This raises the question as to why these proteins in H2O show a normal frequency for the presence of alpha-helical structures and an abnormal frequency in 2H2O. Addition of deuterated glycerol to the proteins in 2H2O solutions results in a significant shift of absorbance to higher frequency.(ABSTRACT TRUNCATED AT 250 WORDS)
Calcium↗
Studies of peptides forming 3(10)- and alpha-helices and beta-bend ribbon structures in organic solution and in model biomembranes by Fourier transform infrared spectroscopy.
In order to examine the potential correlation between infrared absorption spectra and 3(10)- and alpha-helices and beta-bend ribbon structures, the secondary structures of synthetic peptides known to contain pure 3(10)-helices, mixed 3(10)/alpha-helices, and pure beta-bend ribbon structures, based upon X-ray diffraction and NMR studies, have been investigated by using FTIR spectroscopy incorporating resolution-enhancement techniques. Studies of the peptides known to contain a stable 3(10)-helix in CDCl3 show the main amide I band of fully stable 3(10)-helices occurs at 1666-1662 cm-1. Resolution-enhancement methods revealed small contributions at 1681-1678 and 1646-1644 cm-1, while the amide II band occurs at 1533-1531 cm-1. Peptides known to contain both alpha- and 3(10)-helices in their structure exhibit bands characteristic of both types of conformation. Peptides known to fold into the beta-bend ribbon structure show an amide I band maximum at 1648-1645 cm-1 with the amide II band at 1538-1536 cm-1. Incorporation of these peptides into model membrane structures, e.g., DMPC vesicles, in aqueous buffer sometimes produces changes in the peptide secondary structure. Those peptides which possess a 3(10)-helical structure in CDCl3 solution change the secondary structure in DMPC vesicles to predominantly alpha-helical, plus a contribution from short, unstable 3(10)-helix and/or beta-turns. Those peptides which contain a combination of alpha- and 3(10)-helical structures in CDCl3 solution tend to retain some 3(10)-helical structure within the lipid environment, although the overall H-bonding pattern is altered. Those peptides which form a beta-bend ribbon structure appear to be largely unaffected in the membrane environment.(ABSTRACT TRUNCATED AT 250 WORDS)
Amino Acid Sequence↗
Protein secondary structure of the isolated photosystem II reaction center and conformational changes studied by Fourier transform infrared spectroscopy.
The secondary structure of the photosystem II (PSII) reaction center isolated from pea chloroplasts has been characterized by Fourier transform infrared (FTIR) spectroscopy. Spectra were recorded in aqueous buffers containing H2O or D2O; the detergent present for most measurements was dodecyl maltoside. The broad amide I and amide II bands were analyzed by using second-derivative and deconvolution procedures. Absorption bands were assigned to the presence of alpha-helices, beta-sheets, turns, or random structure. Quantitative analysis revealed that this complex contained a high proportion of alpha-helices (67%) and some antiparallel beta-sheets (9%) and turns (11%). An irreversible decrease in the intensity of the band associated with the alpha-helices occurs upon exposure of the isolated PSII reaction center to bright illumination. This loss of alpha-helical content gave rise to an increase in other secondary structures, particularly beta-sheets. After similar pretreatment with light, sodium dodecyl sulfate polyacrylamide gel electrophoresis reveals lower mobility and solubility of constituent D1 and D2 polypeptides of the PSII reaction center. Some degradation of these polypeptides also occurs. In contrast, there is no change in the mobility of the two subunits of cytochrome b559. In the absence of illumination, the PSII reaction center exchanged into dodecyl maltoside shows good thermal stability as compared with samples in Triton X-100. Only at a temperature of about 60 degrees C do spectral changes take place that are indicative of denaturation.
Buffers↗
Venous synchrotron coronary angiography.
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Coronary Angiography↗
Intraperitoneal chemotherapy: analysis of complications with an implanted subcutaneous port and catheter system.
To determine the morbidity associated with delivery of intraperitoneal chemotherapy via subcutaneous semipermanent infusion catheters, we analyzed the data on 227 patients treated from April 1985 through December 1989. A total of 249 catheters were inserted and used to administer chemotherapy in these patients. There were 40 (17.6%) complications associated with the use of 230 original catheters, with 20 patients experiencing catheter inflow obstruction and 20 developing catheter-related infections; the latter group included 8 patients with bowel perforations. Although there was a trend toward an increase in catheter-related infections in association with large bowel surgery and appendectomies, sample size limited statistical analysis. There were 7 (36.8%) complications associated with the use of 19 replacement catheters. This rate was significantly increased (P = 0.03) when compared with the complication rate of original catheters. This system functions well and has an acceptable level of morbidity for delivery of intraperitoneal chemotherapy in gynecologic cancer patients.
Catheterization↗
Prognostic factors for recurrence following negative second-look laparotomy in ovarian cancer patients treated with platinum-based chemotherapy.
Prior studies of the risk of recurrence following negative second-look laparotomy have included patients treated with a variety of chemotherapeutic regimens, including nonplatinum regimens. We have examined the long-term outcome and risk factors for recurrence among a homogeneous group of platinum-treated patients. During the years 1978-1987, 91 patients at Memorial Sloan-Kettering Cancer Center had a negative second-look laparotomy following platinum-based chemotherapy for epithelial ovarian cancer. The mean age at diagnosis was 57 years, with a range of 30 to 79. Distribution by stage was as follows: I, 10; II, 18; III, 57; IV, 6. The mean number of cycles of platinum prior to second-look surgery was 6.3. The mean number of biopsies taken at negative second-look laparotomy was 12. Lymph node biopsies were done in 47/91 (52%) of patients. Median follow-up from the date of second-look laparotomy was 54.6 months among survivors. Forty of ninety-one patients (44%) have had recurrence, almost 40% of which were outside the peritoneal cavity. The mean interval from negative second-look laparotomy to recurrence was 24 months (range, 2-70 months). By multivariate analysis the risk of recurrence was significantly related to stage (P = 0.017), histologic grade (P = 0.041), and the amount of tumor remaining after the first operation for ovarian cancer (P = 0.015). Recurrence by stage was as follows: stage I, 1/10 (10%); stage II, 5/18 (28%); stage III, 31/57 (54%); stage IV, 3/6 (50%). Recurrence by grade was as follows: grade 1, 4/18 (22%); grade 2, 11/28 (39%); grade 3, 25/45 (56%). There was no relationship between the risk of recurrence and the number of cycles of platinum, the number of biopsies performed at second-look, or the number of months from primary surgery to second-look. Patients having negative second-look laparotomy following platinum-based chemotherapy for advanced epithelial ovarian cancer have a substantial risk of recurrence, particularly within the first 3 years. Such patients should be offered participation in clinical trials of consolidation therapy directed against both intraperitoneal and extraperitoneal disease.
Adult↗
Cisplatin-based combination chemotherapy in carcinoma of the fallopian tube.
Forty-three cases of primary tubal adenocarcinoma were treated at Memorial Sloan-Kettering Cancer Center between 1979 and 1989. Thirty-eight patients who received cisplatin-based combination chemotherapy following primary surgery were reviewed. The mean patient age was 59 years, with 86% postmenopausal. Distribution by stage was as follows: I, 3 (7%); II, 4 (11%); III, 27 (71%); and IV, 4 (11%). Median follow-up from the time of diagnosis was 62 months (range, 5-132). Overall survival for all 38 patients by Kaplan-Meier analysis was 51% at 5 years. Excluding stage I, patients with no residual disease following surgery had a significantly higher 5-year survival (83%) than those left with gross residual disease (28%). Twenty-six patients underwent a second-look procedure. Of the 21 patients with advanced (stages III, IV) disease undergoing reexploration, 11 (52%) had a negative second-look and 10 (48%) were positive. Ten of the eleven patients with a negative second-look remain clinically free of disease with a median follow-up of 49 months. One patient with stage III disease had recurred after 47 months. Carcinoma of the fallopian tube appears to respond favorably to cisplatin-based multiagent chemotherapy. Patients with advanced-stage disease who achieve a negative second-look appear to have an improved possibility of remaining disease-free over similar-stage patients with ovarian cancer.
Adult↗
Tropistic responses of Avena seedlings in simulated hypogravity.
Results from investigation of the gravitropic responses of the Avena coleoptile under simulated weightlessness are presented. The tests were conducted using the flight hardware, identified by NASA as the Gravitational Plant Physiology Facility (GPPF), designed to support the Spacelab experiment, GTHRES. Weightlessness or so-called microgravity-conditions were simulated by the use of a so-called somersault clinostat. The plants were gravitropically stimulated with different g-forces and stimulation durations on a centrifuge. Timelapse video pictures of the plants were taken during the last hour prior to the stimulation and in a period of 3 hours after. The gravitropic responses of the plants were analyzed with the aid of an image analyzing system. Dose-response curves for stimulation forces 0.2, 0.4, 0.6, 0.8, and 1.0 g with different stimulation times ranging from 2 to 250 min were achieved. The results show that the reciprocity between force and stimulation time may be valid for small stimulation doses (lower than 5 g min), but not for larger doses. Furthermore, the threshold values (i.e. the smallest stimulation the plants are able to detect) found by extrapolation of the dose response curves, are less than 30 g s. The results are discussed with respect to an accepted space experiment, GTHRES, where the corresponding experiments will be carried out in the same apparatus under true microgravity conditions.
Avena↗
Relationship and prognostic value of endogenous interferon-alpha, beta 2-microglobulin, and neopterin serum levels in patients with Kaposi sarcoma and AIDS.
We investigated whether elevated serum levels of beta 2-microglobulin and neopterin were related to the abnormal in vivo production of interferon described in patients with human immunodeficiency virus (HIV) infection, and whether these factors might add to measurements of CD4+ T cells in predicting survival and tumor regression in patients with Kaposi sarcoma associated with AIDS. beta 2-Microglobulin and neopterin levels were strongly correlated (r = 0.82), and were each significantly higher in patients with detectable serum interferon-alpha activity. Inverse correlations were observed between prognosis and levels of these serum products. Prediction by CD4+ T-cell count of tumor regression after treatment with interferon-alpha and zidovudine was improved by each of two factors: (a) the presence or absence of endogenous interferon-alpha activity, and (b) a combined variable reflecting relative levels of the interferon-inducible products, beta 2-microglobulin and neopterin. The level of beta 2-microglobulin was the single best predictor of survival. When beta 2-microglobulin was not considered, the endogenous interferon-alpha variable was the best predictor of survival, and the prediction was enhanced by addition of the combined variable, or the neopterin value alone. We conclude that serologic markers, which directly or indirectly reflect activation of the endogenous interferon system, may be valuable adjuncts to CD4+ T-cell counts in assessing prognosis and selecting and evaluating treatments for patients with Kaposi sarcoma and AIDS.
Acquired Immunodeficiency Syndrome↗
Determination of protein secondary structure using factor analysis of infrared spectra.
A method is presented for determining the secondary structural composition of a protein in aqueous solution from its infrared spectrum. A factor analysis approach is used to analyze the infrared spectra of 18 proteins whose crystal structures are known from X-ray studies. Factor analysis followed by multiple linear regression identifies those eigenspectra that correlate with the variation in properties described by the calibration set. The properties of interest in this study are % alpha-helix, % beta-sheet, and % turns. In the analysis of an unknown, the factor loadings required to reproduce its spectrum are substituted in the regression equation for each property to predict its secondary structural composition. The accuracy of the method was determined by removing each standard, in turn, from the calibration set and using a calibration set generated from the remainder to predict its composition. By this method we obtain standard errors of prediction of 3.9% for alpha-helix, 8.3% for beta-sheet, and 6.6% for turns. The method may also be applied to the spectra of proteins in 2H2O. The method has important advantages over those currently in use for the quantitative analysis of the infrared spectra of proteins. Manipulation of the spectrum is kept to a minimum, no curve-fitting is necessary, and the several amide I band components need not be assigned.
Calibration↗
A Fourier transform infrared spectroscopic (FTIR) study of porcine and bovine pancreatic phospholipase A2 and their interaction with substrate analogues and a transition-state inhibitor.
Fourier transform infrared spectroscopy has been used to investigate the secondary structure of porcine and bovine pancreatic phospholipase A2 (PLA2) and the zymogen of porcine PLA2, prophospholipase A2 (proPLA2), in both H2O and D2O media. Detailed qualitative analysis was made of these proteins using second derivative and deconvolution techniques. Quantitative studies of the proteins in solution made using Factor Analysis gave average values of 54% alpha-helix, 15% beta-sheet and 23% beta-turns. These values agree well with the secondary structures deduced from previous studies of single crystals using X-ray techniques. No significant differences in secondary structure were observed for porcine pancreatic (pro)phospholipase A2 in the presence or absence of Ca2+ ions, or in the temperature range 10-45 degrees C. The binding of the non-degradable phospholipid analogue, n-alkylphosphocholine, in monomeric form produced no significant difference in the secondary structure of either enzyme. Conformational differences were, however, observed between the enzyme lyophilised in a solid film and in aqueous solution. The change is probably due to the formation of beta-sheet upon hydration, coupled with a loss of random structures. Conformational differences in both porcine and bovine pancreatic PLA2 were observed on binding to n-alkylphosphocholine micelles. This change may be due to a small increase in the alpha-helical structure and a decrease in the beta-sheet, and/or possibly beta-turn content. Similar conformational changes were observed for the interaction of porcine and bovine PLA2 with the substrate analogue inhibitor 1-heptanoyl-2-heptanoylamino-2-deoxy-sn-glycero-3-phospho glycol in micellar form.
Animals↗
Conformational transition between native and reactive center cleaved forms of alpha 1-antitrypsin by Fourier transform infrared spectroscopy and small-angle neutron scattering.
alpha 1-Antitrypsin (alpha 1-AT) is the best-characterized member of the serpin superfamily of plasma proteins. Protease inhibitor members of this family undergo a characteristic reactive-center cleavage during expression of their inhibitory activity. The physical basis of this transition in alpha 1-AT from the stressed native conformation to the more stable reactive center cleaved (split) form was studied by Fourier transform infrared (FT-IR) spectroscopy and neutron scattering. The FT-IR spectra show that, while split alpha 1-AT has three intense well-resolved components associated with the presence of antiparallel beta-sheet and alpha-helix conformations, the amide I band of native alpha 1-AT has only one intense component, associated with the presence of beta-sheet structure. 1H-2H exchange within the polypeptide backbone, studied by FT-IR and NMR spectroscopy, shows that the native form undergoes greater exchange than the split form. Under the same conditions, neutron scattering shows no differences in the radius of gyration RG of the native and the split forms. In contrast, in high concentrations of phosphate approaching those used for crystallization, the native form (unlike the split form) undergoes dimerization. These data indicate that the conformational transition largely involves localized secondary and tertiary structure rearrangements. We propose that the energetically stressed native alpha 1-AT structure is the consequence of a significantly reduced number of hydrogen bonds in secondary structure components and that reactive-site cleavage between Met358 and Ser359 is the key for the development of the fully hydrogen bonded more stable serpin structure.
Fourier Analysis↗
The optional E. coli prr locus encodes a latent form of phage T4-induced anticodon nuclease.
The optional Escherichia coli prr locus restricts phage T4 mutants lacking polynucleotide kinase or RNA ligase. Underlying this restriction is the specific manifestation of the T4-induced anticodon nuclease, an enzyme which triggers the cleavage-ligation of the host tRNALys. We report here the molecular cloning, nucleotide sequence and mutational analysis of prr-associated DNA. The results indicate that prr encodes a latent form of anticodon nuclease consisting of a core enzyme and cognate masking agents. They suggest that the T4-encoded factors of anticodon nuclease counteract the prr-encoded masking agents, thus activating the latent enzyme. The encoding of a tRNA cleavage-ligation pathway by two separate genetic systems which cohabitate E. coli may provide a clue to the evolution of RNA splicing mechanisms mediated by proteins.
Amino Acid Sequence↗
Glycidyl acrylate plasma glow discharged polymers.
A homogeneous glycidyl acrylate polymer (GAP) has been grafted on to polytetrafluoroethylene (PTFE) and polyethylene (PE) using a modified plasma glow discharge technique with glycidyl acrylate. The polymeric layer appears to be extremely stable to acidic media and to common organic solvents. The modified surface can be derivatized via epoxy groups with hydroxy and amino compounds including sugars and amino sugars. These derivatized surfaces have been characterized by Fourier transform infrared (FTIR) spectroscopy and contact angle measurements. The wide variety of compounds which can be attached provides flexibility in the design of surfaces for the study of a range of biological interactions.
Adsorption↗
Expression of fibrillar types I and III and basement membrane collagen type IV genes in myocardium of tight skin mouse.
STUDY OBJECTIVE: The aim was to study the expression of fibrillar collagen types I and III and basement membrane type IV collagen in the heart of the tight skin mouse, a genetic mutant with collagen overproduction in various organs. DESIGN: Collagen gene expression was measured in the ventricular tissues of the heart of the tight skin mouse and the age matched homozygous (+/+) litter mates by the use of cDNA probes to alpha 2 (I), alpha 1 (III) and alpha 2 (IV) procollagen and northern and dot blot analysis. Collagen deposition was examined by immunofluorescent light microscopy using monospecific antibodies to types I, III and IV collagens. EXPERIMENTAL MATERIAL: Heterozygous male (TSK/+) and normal (+/+) mice, 1.5-2 months old of the C57BL/6 strain were used. The animals were anaesthetised and the hearts were rapidly excised and processed for RNA extraction and antibody staining. MEASUREMENTS AND RESULTS: The results of northern and dot blot analyses showed a 41% increase in mRNA level for collagen type I, a 63% increase in mRNA level for type III and a 33% increase in type IV collagen in the ventricular myocardium (right and left ventricles) of the tight skin mouse compared to its counterpart in age matched homozygous (+/+) litter mates. mRNA levels for beta actin showed no significant increase. Immunofluorescent light microscopy and monospecific antibodies to types I, III and IV collagens were used to examine collagen deposition. The results showed that collagen type I fibres are thicker and denser in perivascular areas of the tight skin mouse heart compared to normal heart. No abnormal accumulation of type III fibres was observed. CONCLUSIONS: The heart of the tight skin mouse may be an appropriate model for studying the up regulation of cardiac collagen gene expression and its potential contribution to myocardial diseases.
Animals↗