Breastfeeding. A multimedia learning resource for healthcare professionals.
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Breast Feeding↗
Biomedical subjects
A Spencer
Publications and source records attributed to A Spencer.
Beyond the basics: implementing the HIPAA Privacy Standards in real life situations.
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Journal Article↗
1,3,5-Trialkyl-2,4,6-triiodobenzenes: novel X-ray contrast agents for gastrointestinal imaging.
Examination of the gastrointestinal (GI) tract has been performed for decades using barium sulfate. Although this agent has many recognized limitations including extreme radiopacity, poor intrinsic affinity for the GI mucosa, and very high density, no alternative contrast agents have emerged which produce comparable or better contrast visualization. In fact, the various techniques of the GI radiologic examination (i.e., single contrast, double contrast, biphasic) were developed to compensate for its limitations. Each of these techniques requires complex patient manipulation to achieve adequate mucosal coating or compression to overcome the marked radiopacity of barium sulfate in order to obtain a diagnostically useful examination. A series of novel radiopaque oils, the 1,3, 5-trialkyl-2,4,6-triiodobenzenes, was designed to improve the efficacy, stability, and safety of barium formulations. These substances were prepared in two steps from 1,3,5-trichlorobenzene. Compound 17 (1,3,5-tri-n-hexyl-2,4,6-triiodobenzene), formulated as an oil-in-water emulsion, was found to be well-tolerated in rodents (mice, hamsters, rats) following acute oral and/or intraperitoneal administrations at 4 times the anticipated human clinical dose. No metabolism of 17 was detected in rat, hamster, dog, monkey, or human hepatic microsomes, suggesting the lack of oral toxicity was a consequence of poor absorption. In imaging experiments in dogs, emulsions of 17 have demonstrated excellent mucosal coating and improved radiodensity relative to barium sulfate suspensions. On the basis of the preliminary imaging and toxicity data, compound 17 was selected as a potential development candidate.
Absorption↗
Amyloid fibril formation and seeding by wild-type human lysozyme and its disease-related mutational variants.
Wild-type human lysozyme and its two stable amyloidogenic variants have been found to form partially folded states at low pH. These states are characterized by extensive disruption of tertiary interactions and partial loss of secondary structure. Incubation of the proteins at pH 2.0 and 37 degrees C (Ile56Thr and Asp67His variants) or 57 degrees C (wild-type) results in the formation of large numbers of fibrils over several days of incubation. Smaller numbers of fibrils could be observed under other conditions, including neutral pH. These fibrils were analyzed by electron microscopy, Congo red birefringence, thioflavine-T binding, and X-ray fiber diffraction, which unequivocally show their amyloid character. These data demonstrate that amyloidogenicity is an intrinsic property of human lysozyme and does not require the presence of specific mutations in its primary structure. The amyloid fibril formation is greatly facilitated, however, by the introduction of "seeds" of preformed fibrils to the solutions of the variant proteins, suggesting that seeding effects could be important in the development of systemic amyloidosis. Fibril formation by wild-type human lysozyme is greatly accelerated by fibrils of the variant proteins and vice versa, showing that seeding is not specific to a given protein. The fact that wild-type lysozyme has not been found in ex vivo deposits from patients suffering from this disease is likely to be related to the much lower population of incompletely folded states for the wild-type protein compared to its amyloidogenic variants under physiological conditions. These results support the concept that the ability to form amyloid is a generic property of proteins, but one that is mitigated against in a normally functioning organism.
Amyloid↗
Agreement among four homocysteine assays and results in patients with coronary atherosclerosis and controls.
BACKGROUND: Hyperhomocysteinemia has been associated with coronary atherosclerosis in many, but not all, prospective and retrospective studies. Some on these inconsistencies may be attributed to methodological variabilities. METHODS: In the present study, three newly commercially available assays and one in-house HPLC assay for total homocysteine (tHcy) were utilized in 99 subjects with angiographically documented atherosclerosis and in 91 community controls matched by age, gender, and smoking history. The in-house assay, a modified Fortin and Genest HPLC method, was compared with the Bio-Rad HPLC assay, the Abbott IMx((R)) fluorescence polarization immunoassay, and a Bio-Rad enzyme-linked immunoassay (EIA) microtiter method. RESULTS: Correlation coefficient values between the in-house HPLC assay and the Bio-Rad HPLC, the Abbott IMx, and the Bio-Rad EIA assays were 0.95, 0.96 and 0.90, respectively. Although tHcy concentrations were higher in cases compared with controls by all four methods, the difference reached statistical significance only with the in-house HPLC procedure (median, 13.5 +/- 6.7 micromol/L in cases vs 10.9 +/- 4.8 micromol/L in controls; P <0. 01, adjusting for covariates), where it was an independent predictor of case or control status, along with hypertension, total cholesterol, and triglycerides. The tHcy distributions in cases and controls demonstrated significant overlap. The number of atherosclerotic major coronary vessels was associated with significantly higher tHcy (P <0.01 for trend) in all four methods. CONCLUSIONS: The three commercial assays for tHcy differed in analytical and clinical performance. Analytically, the Abbott IMx method showed the best comparability with the in-house assay, but clinically, the three commercial methods were similar and did not distinguish cases from controls.
Arteriosclerosis↗
Evaluation of four automated high-sensitivity C-reactive protein methods: implications for clinical and epidemiological applications.
BACKGROUND: C-reactive protein (CRP) can provide prognostic information about the risk of developing atherosclerotic complications in apparently healthy patients. This new clinical application requires quantification of CRP concentrations below those traditionally measured in the clinical laboratory. METHODS: The Dade Behring BN II, the Abbott IMx, the Diagnostic Products Corporation IMMULITE, and the Beckman Coulter IMMAGE are four automated analyzers with high-sensitivity CRP (hs-CRP) methods. We evaluated these assays for precision, linearity, and comparability with samples from 322 apparently healthy blood donors. RESULTS: The imprecision (CV) of the BN II, IMx, IMMULITE, and IMMAGE methods was < or = 7.6%, < or = 12%, < or = 9.8%, and < or = 9.7% at 3.5 mg/L, respectively. The BN II, IMx, IMMULITE, and IMMAGE methods were linear down to < or = 0.30, < or = 0.32, < or = 0.85, and 2.26 mg/L, respectively. CRP concentrations demarcating each quartile in a healthy population were method dependent. The IMx method gave results comparable to the BN II method for values in the reference interval. The IMMULITE method had a positive intercept compared with the BN II method. The IMMAGE method demonstrated more scatter and a positive intercept compared with the BN II method, which may reflect the fact that it is a less sensitive assay. CONCLUSIONS: The four hs-CRP methods exhibited differences in results for a healthy population. Additional standardization efforts are required to ensure that hs-CRP results can be related to large-scale epidemiologic studies.
Adolescent↗
Mechanistic studies of the folding of human lysozyme and the origin of amyloidogenic behavior in its disease-related variants.
The unfolding and refolding properties of human lysozyme and two amyloidogenic variants (Ile56Thr and Asp67His) have been studied by stopped-flow fluorescence and hydrogen exchange pulse labeling coupled with mass spectrometry. The unfolding of each protein in 5.4 M guanidine hydrochloride (GuHCl) is well described as a two-state process, but the rates of unfolding of the Ile56Thr variant and the Asp67His variant in 5.4 M GuHCl are ca. 30 and 160 times greater, respectively, than that of the wild type. The refolding of all three proteins in 0.54 M GuHCl at pH 5.0 proceeds through persistent intermediates, revealed by multistep kinetics in fluorescence experiments and by the detection of well-defined populations in quenched-flow hydrogen exchange experiments. These findings are consistent with a predominant mechanism for refolding of human lysozyme in which one of the structural domains (the alpha-domain) is formed in two distinct steps and is followed by the folding of the other domain (the beta-domain) prior to the assembly of the two domains to form the native structure. The refolding kinetics of the Asp67His variant are closely similar to those of the wild-type protein, consistent with the location of this mutation in an outer loop of the beta-domain which gains native structure only toward the end of the refolding process. By contrast, the Ile56Thr mutation is located at the base of the beta-domain and is involved in the domain interface. The refolding of the alpha-domain is unaffected by this substitution, but the latter has the effect of dramatically slowing the folding of the beta-domain and the final assembly of the native structure. These studies suggest that the amyloidogenic nature of the lysozyme variants arises from a decrease in the stability of the native fold relative to partially folded intermediates. The origin of this instability is different in the two variants, being caused in one case primarily by a reduction in the folding rate and in the other by an increase in the unfolding rate. In both cases this results in a low population of soluble partially folded species that can aggregate in a slow and controlled manner to form amyloid fibrils.
Amyloid↗
Side-chain conformations in an unfolded protein: chi1 distributions in denatured hen lysozyme determined by heteronuclear 13C, 15N NMR spectroscopy.
Using a 13C and 15N-labelled sample, multi-dimensional heteronuclear NMR techniques have been carried out to characterise hen lysozyme denatured in 8 M urea at pH 2.0. The measurement of 3J(C',Cgamma) and 3J(N,Cgamma) coupling constants has enabled side-chain chi1 torsion angle populations to be probed in the denatured polypeptide chain. Analysis of the coupling constant data has allowed the relative populations of the three staggered rotamers about chi1 to be defined for 51 residues. The amino acids can broadly be divided into five classes that show differing side-chain conformational preferences in the denatured state. These range from a strong preference for the -60 degrees chi1 rotamer for methionine and leucine (74-79 % population) to a favouring of the +60 degrees chi1 rotamer for threonine (67 % population). The differences in behaviour reflect the steric and electrostatic characteristics of the side-chains concerned. A close agreement is seen between the chi1 populations calculated from the experimental coupling constant data and predictions from the statistical model for a random coil that uses the chi1 torsion angle distributions in a data base of native protein structures. Short-range interactions therefore dominate in determining the local conformational properties of side-chains in a denatured protein. Deviations are, however, observed for many of the aromatic residues involved in hydrophobic clusters within the denatured protein. For these residues the effects of additional non-local interactions in the clusters presumably play a major role in determining the chi1 preferences.
Animals↗
Screening for inborn errors of metabolism in children.
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Child↗
Expression, purification, and characterization of the recombinant calcium-binding equine lysozyme secreted by the filamentous fungus Aspergillus niger: comparisons with the production of hen and human lysozymes.
Equine lysozyme (EqL) has been expressed from a synthetic gene and secreted from a heterologous host, the filamentous fungus Aspergillus niger. By including 100 mM Ca2+ in the growth medium, secreted yields of more than 50 mg/liter could be achieved using polyvinylpyrrolidone (PVP) complete medium. In a soya medium yields of up to 150 mg/liter were achieved. The production of recombinant human lysozyme (HuL) from A. niger with yields of over 40 mg/liter was also achieved using PVP medium. Addition of Ca2+ to the growth medium reduced the yield of both HuL and hen egg white lysozyme (HEWL). Sequence differences between the three lysozymes, EqL, HuL, and HEWL, resulted in different susceptibilities to cleavage by A. niger proteases. An improved procedure for the purification of EqL and HuL from A. niger allowed separation of the proteins from pigments produced by the fungus. Detailed spectroscopic analysis, including 2D 1H NMR, for recombinant EqL and recombinant HuL confirm that both proteins possess their native structure and are purified to homogeneity.
Amino Acid Sequence↗
Leukemia patient-derived lymphoblastoid cell lines exhibit increased induction of leukemia-associated transcripts following high-dose irradiation.
Improvement in diagnostic cytogenetic techniques has led to the recognition of an increasing number of leukemia-associated chromosomal translocations and inversions. These genetic lesions frequently are associated with the disruption of putative transcription factors and the production of hybrid transcripts that are implicated in leukemogenesis. Epidemiologic evidence suggests that some, but not all, individuals with a history of gamma-irradiation exposure are at increased risk of developing chronic myeloid leukemia (CML). CML is characterized by the Philadelphia chromosome and transcription of the resulting hybrid BCR-ABL gene. Utilizing the leukemia-associated BCR-ABL p210 transcript as a marker, we sought differences in the induction of illegitimate genetic recombination following high-dose gamma-irradiation of karyotypically normal lymphoblastoid cell lines (LCL) derived from individuals with and without a history of myeloid leukemias. Six LCL [4 leukemia patient derived [2 acute myeloid leukemia and 2 CML] and 2 from normal individuals were analyzed with reverse transcriptase polymerase chain reaction for BCR-ABL under stringent conditions following exposure to 0, 50, or 100 Gy of LET gamma-irradiation delivered via a Varian linear accelerator at 4 MV. Transcripts identical to disease-associated b2a2 and b3a2 transcripts were detected both spontaneously (background illegitimate genetic recombination) and following gamma-irradiation. Background BCR-ABL positivity was demonstrable in 4 of the 6 LCL, with no significant difference in detection between leukemic- and nonleukemic-derived LCL. Overall, increasing gamma-irradiation dose resulted in an increased frequency of BCR-ABL transcript detection (0 Gy vs 50 Gy vs 100 Gy,p = 0.0023, Chi-square test). Within the leukemic- but not the nonleukemic-derived LCL there was significantly greater BCR-ABL positivity after gamma-irradiation compared to unirradiated equivalents. Furthermore, the BCR-ABL positivity of both the AML- and CML-derived LCL after gamma-irradiation was significantly greater than that of the nonleukemic-derived LCL after gamma-irradiation. We speculate that this difference in the detection of illegitimate after gamma-irradiation recombination may be due to aberrant DNA double strand break repair mechanisms in individuals predisposed to the development of myeloid leukemias.
Acute Disease↗
Whole blood manganese levels in pregnancy and the neonate.
A finding of hypermanganesemia was reported in a pregnant female who received total parenteral nutrition (TPN) for a total of 27 wk as a result of intractable Hyperemesis gravidarum. It was assumed this was the result of the TPN therapy which included manganese (Mn) supplementation. However, the Mn levels continued to rise despite ceasing supplemental Mn, and no evidence of hepatic cholestasis. These high levels were also observed in the 10-d-old neonate, despite a fall in the mother's levels at parturition. A cross sectional study of 19 females at 34 wk pregnancy showed six (31.5%) were outside the quoted reference range for Mn levels. This study was undertaken to monitor Mn levels throughout the pregnancy period and in the neonate in the initial post partum period. Thirty-four pregnant females were randomly recruited from the Gold Coast Hospital antenatal clinic. Whole blood Mn levels were determined for each female on three separate occasions during the trial, at the first visit to the clinic (10-20 wk) and at 25 wk and 34 wk gestation. Mn levels were also determined from blood taken from the baby at neonatal screening (3-4 d old) by heel prick. There was a significant increase in the mean whole blood Mn levels throughout the pregnancy (P<0.0025 and P<0.0005, respectively) and an average three-fold increase in this level in the neonate (P<0.0005). The data confirms a concentrating effect of Mn, as measured by whole blood levels, throughout pregnancy and more dramatically so in the neonate which may indicate a vital role in fetal development.
Australia↗
Arsenic trioxide treatment of relapsed acute promyelocytic leukaemia: initial Australian experience.
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Adult↗
CD10 positive thyroid marginal zone non-Hodgkin lymphoma.
A 72 year old woman presented with swelling of the right lobe of her thyroid gland. Fine needle aspiration and flow cytometry showed a clonal population of B cells expressing CD10 and a diagnosis of follicle centre cell lymphoma was made. Subsequent excision of the thyroid showed the typical histological features of a marginal zone non-Hodgkin lymphoma. Polymerase chain reaction showed no evidence of t (14;18). Immunohistochemistry confirmed CD10 positivity and LN1 (CDw75) expression. This is only the second report of aberrant expression of CD 10 by a marginal zone lymphoma.
Aged↗
Abnormal patterns of immunoglobulin heavy chain gene DNA fingerprinting during chronic phase chronic myeloid leukemia.
Using IgH DNA fingerprinting we have previously demonstrated clonal immunoglobulin heavy chain (IgH) gene rearrangements during chronic phase (CP) chronic myeloid leukemia (CML) in patients destined to develop lymphoid blast crisis (L-BC). In view of this we decided to follow a cohort of CP CML patients to determine the frequency with which abnormal IgH fingerprints are found and their relationship, if any, to treatment regimen. Thirty three, initially CP, CML patients were studied on 111 occasions over a 16 month period using consensus PCR amplification of the third complementarity determining region (CDR3) of the IgH gene and high resolution polyacrylamide gel electrophoresis (IgH DNA fingerprinting). Of these 33 patients, thirteen received interferon-alpha (IFN) containing regimens and 15 non-IFN containing regimens throughout the study period. Five patients received variable therapy. During the period of observation 7 patients experienced disease progression: 5 accelerated phase, I L-BC and I myeloid blast crisis (M-BC). Abnormal IgH fingerprints were seen in 29 of the 111 (26%) specimens analysed. The 28 patients who received uniform therapy (IFN or non-IFN) over the 16 months were classified as "normal" (n = 18, normal pattern on all occasions) or "abnormal" (n = 10, abnormal on 1 or more occasions). Analysis by patient group (normal vs abnormal) showed that fingerprint abnormalities were associated with an elevated peripheral blood lymphocyte count (p = 0.0001) but not with changes in the total white cell count. Comparison of the IFN vs. non-IFN groups showed the former all had normal patterns whereas 10 of 15 non-IFN therapy patients were abnormal (p = 0.00023). The peripheral blood lymphocyte counts in the normal vs abnormal patients within the non-IFN group were not significantly different. The patient who developed L-BC demonstrated a persistent IgH fingerprint pattern abnormality from 7 months prior to the diagnosis of L-BC. The M-BC patient had a normal pattern at all times. We conclude that: (1) abnormal IgH fingerprints are found in a significant number of CP CML patients; (2) in this cohort the use of IFN was associated with normal CP CML IgH fingerprints, and (3) detection of abnormal IgH fingerprints may be highly predictive for the lineage of impending blast crisis.
DNA Fingerprinting↗
Chronic dietary inositol enhances locomotor activity and brain inositol levels in rats.
myo-Inositol has been found to be clinically effective in depression, obsessive compulsive disorder (OCD) and panic disorder when given chronically per os. The present study examined the effects of chronic dietary inositol in rats on locomotor behaviour. Regional brain levels of inositol were analyzed by gas chromatography. Chronic dietary inositol significantly enhanced locomotion and rearing in rats and elevated inositol levels by 36% in the cortex and 27% in hippocampus. No differences in inositol levels were found in the striatum or cerebellum. The stimulatory effects of inositol may be related to its effects as an atypical antidepressant in depressed patients.
Analysis of Variance↗
Allocating resources in health care: alternative approaches to measuring needs in resource allocation formula in Ontario.
Maintaining or improving the welfare of the population is a complex issue involving individual and collective actions and institutions. Despite questions regarding the relevance of health care systems to these aims, they remain vital policy and treatment arenas with respect to curative and preventative regimes. As a component of social welfare, health care resources should be distributed equitably, according to need for health care. This paper evaluates alternative indicators of health status within Ontario against self-reported health as a means of allocating health care resources. Proxies of need for health care include standardized mortality ratios (based on the population aged 0-64) and a socioeconomic based indicator. Mortality indicators are found to be more closely correlated with self-reported health status than the socioeconomic indicator, suggesting that mortality is better able to reflect variations in health status and health care needs.
Adolescent↗
Collection and analysis of peripheral blood mononuclear cells during haemopoietic recovery following PBSCT for CML: autografting as an in vivo purging manoeuvre?
A 47-year-old man with a 2-year history of Philadelphia chromosome-positive chronic phase (CP) chronic myeloid leukaemia (CML) underwent autologous PBSCT. During the period of haemopoietic reconstitution he underwent five leucapheretic (LP) harvests yielding a total of 2.6 x 10(6)/kg CD34+ cells. Cytogenetic analyses revealed 94, 83, 83, 96 and 85% Ph negativity respectively for the five harvests. RT-PCR analyses for BCR-ABL performed on randomly picked CFU-GM from the five LP products were negative in all cases. These observations suggest that the majority of harvested cells, including the more primitive clonogenic cells, were BCR-ABL (Ph) negative and presumably were not part of the leukaemic clone. These findings support the notion that autologous PBSCT in CML whilst serving as a therapeutic manoeuvre may also facilitate the collection of non-leukaemic progenitor cells for further transplantation procedures.
Hematopoiesis↗