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Biomedical subjects

A K Taylor

Publications and source records attributed to A K Taylor.

At least 55 records · Page 3Linked to original sources
PubMed1993

Changes in markers of bone formation and resorption in a bed rest model of weightlessness.

To study the mechanism of bone loss in physical unloading, we examined indices of bone formation and bone resorption in the serum and urine of eight healthy men during a 7 day -6 degrees head-down tilt bed rest. Prompt increases in markers of resorption--pyridinoline (PD), deoxypyridinoline (DPD), and hydroxyproline (Hyp)/g creatinine--during the first few days of inactivity were paralleled by tartrate-resistant acid phosphatase (TRAP) with significant increases in all these markers by day 4 of bed rest. An index of formation, skeletal alkaline phosphatase (SALP), did not change during bed rest and showed a moderate 15% increase 1 week after reambulation. In contrast to SALP, serum osteocalcin (OC) began increasing the day preceding the increase in Hyp, remained elevated for the duration of the bed rest, and returned to pre-bed rest values within 5 days of reambulation. Similarly, DPD increased significantly at the onset of bed rest, remained elevated for the duration of bed rest, and returned to pre-bed rest levels upon reambulation. On the other hand, the other three indices of resorption, Hyp, PD, and TRAP, remained elevated for 2 weeks after reambulation. The most sensitive indices of the levels of physical activity proved to be the noncollagenous protein, OC, and the collagen crosslinker, DPD. The bed rest values of both these markers were significantly elevated compared to both the pre-bed rest values and the post-bed rest values. The sequence of changes in the circulating markers of bone metabolism indicated that increases in serum OC are the earliest responses of bone to head-down tilt bed rest.

Acid Phosphatase↗
PubMed1993

Latina and African American women: continuing disparities in health.

Women of all races have faced incredible challenges as they sought to realize the promises of America. For women of color, these challenges were compounded by the second-class citizenship of U.S. racial and ethnic minority population groups. In an effort to assess the quality of life experienced by Latina and African American women, this article provides descriptive information on racial/ethnic differences in women's social conditions, health status, exposure to occupational and environmental risks, and use of health services. When possible, indices are stratified by family income to limit the effects of social class on the comparison of racial differences. The authors provide evidence that Latina and African American women are more likely than nonminority women to encounter social environments (e.g., poverty, densely populated neighborhoods, hazardous work conditions) that place them at risk for ill-health and injury. Although persistent racial disparities in health are often attributed to the lifestyle behaviors of racial minority populations, they are undoubtedly a consequence of poorer social conditions as well as barriers in access to quality health services. To achieve further gains, public policies must reduce social inequalities (i.e., by gender, race, and social class) and assure greater equity in access to resources that facilitate healthier environments and lifestyles. Public health initiatives should be community-based, reflecting a shared partnership that actively engages minority women in decision-making about their lives.

Adolescent↗
PubMed1993

Synthetic peptide-based immunoassay for amino-terminal propeptide of type I procollagen: application for evaluation of bone formation.

Serum biochemical markers are powerful tools for the evaluation of bone turnover. In this study, we developed a radioimmunoassay, using a synthetic peptide for the N-terminal fragment of human type I [alpha 1(I)] procollagen (N-PCP). A 14-amino acid peptide was synthesized from the amino terminus and used to generate antibodies in rabbits. The synthetic peptide was used as standard and tracer in the assay. Both native type I amino procollagen (PINP), which was purified from skin fibroblasts, and human serum displaced tracer binding in parallel with the synthetic peptide. The range for measurement of N-PCP in serum was 0.7 to 30 micrograms/L (0.21-9.18 nmol/L). In a sample of 17 normal adults and 13 children (ages 9-16 years) there was a strong correlation between serum N-PCP determined by this assay and both skeletal alkaline phosphatase isoenzyme and osteocalcin, markers of bone formation. Serum concentrations of N-PCP in a group of normal children were eightfold higher than concentrations in normal adults, with no overlap between the two groups. N-PCP also correlated with C-terminal type I procollagen determined with a commercially available kit (r = 0.92).

Adolescent↗
PubMed1992

Bone-resorption markers galactosyl hydroxylysine, pyridinium crosslinks, and hydroxyproline compared.

We compared the clinical performances of four bone-resorption (BR) assays (hydroxyproline, HYP; galactosyl hydroxylysine, GHYL; deoxypyridinoline, DPD; and pyridinoline, PYD) in subjects with different BR rates: normal (adult men and premenopausal women), mildly increased (postmenopausal osteoporotic women), high (Paget disease patients), and very high (children). The discrimination power (Z score) and the accuracy (estimated by receiver-operating characteristic analysis) for GHYL, DPD, and PYD were compared with those for HYP. Discrimination power and accuracy were similar for high- and very-high-BR groups for all four assays. However in the mildly increased-BR group, DPD, GHYL, and PYD showed a higher discrimination power and accuracy than did HYP. The clinical performances of HYP, DPD, GHYL, and PYD are comparable for large changes in BR. For modest changes, DPD, GHYL, and PYD are more accurate and have a higher discrimination power than does HYP.

Adult↗
PubMed1991

Quantitation of growth factors in ossein-mineral-compound.

Study was undertaken to identify polypeptide factors in the commercially available ossein-mineral-compound and to see if they are present in a biologically relevant quantity. Using the guanidine-EDTA extraction, 35.7 +/- 0.1 mg proteins were obtained from 1 g of the ossein-mineral-compound. At concentration 1 micrograms/ml, guanidine-EDTA-extractable proteins stimulated the incorporation of thymidine into DNA by human bone cells to 581 +/- 122% (p less than 0.001) of that by bovine serum albumin-treated control cells, decreasing thereafter. Similarly, it stimulated the activity of alkaline phosphatase in the human bone cells. Growth factors IGF-I, IGF-II, and TGF-beta were identified in the ossein-mineral-compound. This leads to speculation regarding possible role of growth factors in explaining the beneficial effects of the compound in retarding bone loss in patients with osteoporosis.

Animals↗
PubMed1991

Carboxyl ester lipase: a highly polymorphic locus on human chromosome 9qter.

Carboxyl ester lipase (CEL) is a major component of pancreatic juice and is responsible for the hydrolysis of cholesterol esters as well as a variety of other dietary esters. As part of an effort to elucidate the role of this enzyme in the genetic control of lipid metabolism, we report here the chromosomal mapping of the gene for CEL to the most distal part of the long arm of human chromosome 9 using analysis of mouse-human somatic cell hybrids and in situ hybridization to chromosomes. A chromosome 9 translocation was utilized to determine the position of the CEL gene relative to various genetic markers previously localized to this region. Finally, we report that the CEL locus exhibits a high degree of polymorphism and contains a hypervariable region of the insertion/deletion variety.

Animals↗
PubMed1990

Quantitation of growth factors IGF-I, SGF/IGF-II, and TGF-beta in human dentin.

Human bone matrix is known to contain a battery of polypeptide growth factors. Since dentin is a mineralized tissue similar to bone in composition and perhaps in formation, human dentin was assayed for the presence of similar growth factors. Root dentin proteins were extracted by demineralization in 4 M guanidine hydrochloride (Gu) and 30 mM Tris (pH 7.4) containing 20% EDTA and proteinase inhibitors. Gu-EDTA extracts were desalted and used for the following assays: (1) bone cell proliferation in chick calvarial cell mitogenic assay using the incorporation of [3H]thymidine into TCA-insoluble material; (2) osteocalcin by radioimmunoassay (RIA); (3) insulin-like growth factor I (IGF-I) by RIA; (4) skeletal growth factor/insulinlike growth factor II (SGF/IGF-II) by radioreceptor assay; and (5) transforming growth factor beta (TGF-beta) by bioassay. Gu-EDTA extracts stimulated bone cell proliferation. At 10 micrograms/ml, dentin proteins increased the incorporation of [3H]thymidine by calvarial cells to 320% of that by BSA-treated control cells. Consistent with the presence of mitogenic activity, growth factors were found in dentin in the following concentrations (ng/micrograms Gu-EDTA protein): (1) IGF-I, 0.06; (2) SGF/IGF-II, 0.52; and (3) TGF-beta, 0.017. All three growth factors were present in concentrations lower than that found in human bone. Osteocalcin was detected at a concentration of 3.0 mg/g Gu-EDTA protein, also much lower than that in bone.

Calcium↗
PubMed1990

Assignment of the human gene for CREB1 to chromosome 2q32.3-q34.

The nuclear phosphoprotein cAMP-response-element-binding-protein 1 (CREB1) is involved in the transcriptional regulation of cAMP-inducible genes. We have determined the chromosomal location of the human CREB1 gene by using a cDNA probe. Southern blot analysis of genomic DNA from a panel of mouse-human somatic cell hybrids indicated that the CREB1 gene resides on human chromosome 2. Analysis of a somatic cell hybrid containing a chromosome 2 translocation narrowed assignment of the CREB1 locus to the terminal third of chromosome 2. Finally, in situ hybridization allowed localization of the gene to the 2q32.3-q34 region. This knowledge may prove valuable in molecular analysis of translocations occurring in this region and in exploring the possibility of a role for the CREB1 locus in malignancy.

Animals↗
PubMed1990

A comparative efficacy and safety study of teicoplanin plus aztreonam versus gentamicin plus piperacillin in haematology oncology patients with clinically diagnosed septicaemia.

Infections due to Gram-positive bacteria, especially coagulase-negative staphylococci, have been increasing in immunocompromised patients during the last 5 years because of an increased use of Hickman catheters and oral gut decontamination with quinolones. Teicoplanin, a new glycopeptide antibiotic, has a long plasma half-life which allows once-a-day bolus administration, making it a 'user friendly' agent. A randomized comparative evaluation of teicoplanin plus aztreonam versus gentamicin plus piperacillin in leukaemic patients with a clinical diagnosis of septicaemia was undertaken. The objectives of this study were (1) to evaluate the efficacy and safety of teicoplanin and aztreonam in comparison to a 'standard antibiotic' regimen and (2) to assess the local and systemic tolerance of these drugs. Results of the study in more than 70 patients to date are presented, and the role of anti-Gram-positive antibiotics in the management of severe sepsis in immunocompromised patients is discussed.

Adult↗
PubMed1990

Multiple osteocalcin fragments in human urine and serum as detected by a midmolecule osteocalcin radioimmunoassay.

Reliable markers of bone formation are essential to the investigation of metabolic bone disorders. In this regard, evidence indicates that circulating levels of human osteocalcin (OC) correlate with the skeletal isoenzyme of alkaline phosphatase and can be used as an index of bone formation. A disadvantage of using serum OC as a marker of formation is its diurnal variation. To address this problem we carried out our studies to determine the usefulness of urine in the assessment of bone turnover. Using a midmolecule specific human OC RIA, we were able to detect OC in urine of normal adults (42 mugeq/g creatinine), normal children (849 mu/geq/g creatinine), and Paget's disease patients (613 mugeq/g creatinine). Immunoreactive fragments of OC in human urine and human serum were separated by high pressure liquid chromatography. Multiple fragments were found in normal adult urine that were not detected in normal adult serum. Uremic and Paget's disease sera contain several immunoreactive forms of OC, other than the intact molecule, not found in normal adult serum. Additionally, both Paget's disease sera and urine contained a specific peak of immunoreactive material, eluting at 25% acetonitrile, that was not found in any other serum or urine tested. Urinary OC (uOC) correlated with both skeletal alkaline phosphatase (r = 0.91) and serum OC (r = 0.83), indices of skeletal formation. While uOC has a diurnal variation similar to that of serum OC, determinations of 24-h uOC give integrated values of daily bone turnover rates. Z-Score analysis indicates that uOC (z = 14.04) is better able to distinguish between normal children with high bone turnover and normal adults than either skeletal alkaline phosphatase (z = 8.87) or serum OC (z = 9.01).

Adult↗
PubMed1990

Community outbreak of invasive group A streptococcal infection.

In a two-month period, three cases of septicaemia and one of suppurative tenosynovitis caused by a single strain of Lancefield group A streptococcus, serotype T/M/R 3/3/3, occurred in the district of Nairn (population: 10,239). A primary portal of entry for the organism could not be identified in any of the cases. Laboratory isolates from all four patients were highly susceptible to beta-lactam antibiotics, but prompt treatment failed to prevent the deaths of two previously healthy adults. Group A streptococci of M-type 3 have not previously been associated with outbreaks of invasive infection.

Disease Outbreaks↗
PubMed1989

Identification of a zinc finger protein that binds to the sterol regulatory element.

Cholesterol balance in mammalian cells is maintained in part by sterol-mediated repression of gene transcription for the low density lipoprotein receptor and enzymes in the cholesterol biosynthetic pathway. A promoter sequence termed the sterol regulatory element (SRE) is essential for this repression. With the use of an oligonucleotide containing the SRE to screen a human hepatoma complementary DNA expression library, a clone for a DNA binding protein was isolated that binds to the conserved SRE octanucleotide in both a sequence-specific and a single-strand--specific manner. This protein contains seven highly conserved zinc finger repeats that exhibit striking sequence similarity to retroviral nucleic acid binding proteins (NBPs). We have designated the protein "cellular NBP" (CNBP). CNBP is expressed in a wide variety of tissues, is up regulated by sterols, and exhibits binding specificity that correlates with in vivo function. These properties are consistent with a role in sterol-mediated control of transcription.

Amino Acid Sequence↗
PubMed1989

Premiums, benefits, and employee choice of health insurance options.

Determinants of health insurance choices are estimated from a logit model and data from the National Medical Care Expenditure Survey. Employees offered a choice between traditional health insurance plans chose the high option and the low option in roughly equal numbers. About a quarter of the employees who were offered enrollment in an HMO selected the HMO in preference to a traditional plan. Prices figured significantly in both types of decisions, with the choice between traditional plans about twice as sensitive to prices as the decision to enroll in an HMO. Comprehensive hospital benefits and superior catastrophic protection also appeared to be important factors in the choice of health insurance plans.

Choice Behavior↗
PubMed1989

Interhemispheric interaction when both hemispheres have access to the same stimulus information.

Right-handed Ss identified consonant-vowel-consonant (CVC) nonsense syllables presented tachistoscopically. The CVC on each trial was presented to the left visual field-right hemisphere (LVF-RH), to the right visual field-left hemisphere (RVF-LH), or the same CVC was presented to both visual fields (bilateral presentation). When recognition was incorrect, the pattern of errors was qualitatively different on LVF-RH and RVF-LH trials, suggesting that each cerebral hemisphere has its own preferred mode of processing the CVC stimuli. The qualitative pattern of errors on bilateral trials was identical to that obtained on LVF-RH trials. The bilateral results are described well by a model that assumes the mode of processing characteristic of the RH dominates on bilateral trials but is applied to both the LVF-RH and RVF-LH stimuli.

Adult↗
PubMed1988

Development of a new radioimmunoassay for human osteocalcin: evidence for a midmolecule epitope.

Osteocalcin is a vitamin K-dependent bone-specific protein that can be found circulating in the serum. The circulating levels of osteocalcin have been shown to be an index of bone turnover. Existing radioimmunoassays for osteocalcin have been shown to be specific for C-terminal epitopes, a region that is identical in the human and bovine osteocalcin. There are, however, five amino acids different in the N-terminal region of the molecule. We describe here an immunoassay for a midmolecule epitope of osteocalcin using osteocalcin purified from human femoral head bone powder. Antibody specificity was determined using tryptic digests and a synthetic fragment of human osteocalcin. This assay has only a partial crossreactivity with bovine osteocalcin. This is the first report of an assay against a midmolecular epitope of osteocalcin involving a region in which the human and bovine osteocalcins differ. Osteocalcin levels determined by this assay have a significant correlation with both the total serum alkaline phosphatase and the serum skeletal alkaline phosphatase levels in normal adult human serum and, to a greater degree, in sera of patients with conditions associated with increased bone turnover (Paget's disease, hyperparathyroidism, and newborn sera). These correlations are greater than those previously reported for C-terminal assays, suggesting the possibility that different regions of the molecule may elicit different information concerning bone turnover.

Adult↗
PubMed1988

Multitask investigation of individual differences in hemispheric asymmetry.

Right-handed subjects (N = 120) participated in four different laterality tasks designed to measure aspects of cerebral hemisphere asymmetry: identification of dichotically presented consonant-vowel syllables (CVs), examination of the effects of concurrent repetition of CVs and concurrent anagram solution on finger-tapping by the right and left hands, lateralized identification of CVs presented tachistoscopically to the left and right visual fields, and left/right biases on a free-vision face task involving judgments of emotion. Ear differences in the dichotic listening task were related to the pattern of lateralized interference in the dual-task finger-tapping paradigm. There were no other significant relations between pairs of tasks, but when the present results are considered in the light of other recent experiments, there appears to be a relation between lateral bias on the free-vision face task and visual field differences in tachistoscopic identification. The pattern of results has implications for hypothesized individual differences among right-handers in cerebral dominance for verbal processes, input pathway dominance, and asymmetric arousal of the two cerebral hemispheres.

Adult↗