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At least 163 records · Page 9Linked to original sources
PubMed2005

Correlation of the gradient diffusion coefficients of human lactoferrin with interparticle interactions validated by photon correlation spectroscopy.

The gradient diffusion coefficients of recombinant human lactoferrin, a glycoprotein that is of commercial interest, have been extensively investigated theoretically and experimentally. A theoretical prediction was developed to allow calculation of the thermodynamic coefficient in terms of the electrostatic repulsive forces, London-van der Waals forces, entropic forces and additional interactions of unknown source and determination of the hydrodynamic coefficient by a perturbation theory method. In addition, dilute limit calculations were carried out for both of them. The thermodynamic and hydrodynamic coefficients were incorporated in the generalised Stokes-Einstein equation to calculate the gradient diffusion coefficient. Dynamic light scattering experiments were also conducted under different physiochemical conditions in which the gradient diffusion coefficients and the mean sizes of the macromolecules were measured. It was shown that of the theoretical approaches studied, good quantitative agreement between theory and experiment was found.

Algorithms↗
PubMed1998

Pathological-radiological correlations: pathological and radiological correlation of endobronchial neoplasms: part II, malignant tumors.

The majority of lung neoplasms are malignant. Many of these are central and have an associated endobronchial component. Most such neoplasms are of surface epithelial origin; however, neoplasms of submucosal gland, mesenchymal, and lymphoreticular origin may also demonstrate an endobronchial component. Because of their endobronchial location and associated symptoms, these patients often present at an earlier stage than purely parenchymal lung malignancies. The radiographic features in such cases may be similar to those associated with benign endobronchial tumors; however, there are certain radiological signs that are more suggestive of a malignant process. Despite these circumstances, conservative management such as endoscopic excision are inappropriate in most instances. The clinicopathologic and radiological features of these lesions are detailed.

Bronchial Neoplasms↗
PubMed1985

A new class of cardiotonic agents: structure-activity correlations for natural and synthetic analogues of the alkaloid A new class of A new class of cardiotonic agents: structure-activity correlations for natural and synthetic analogues of the alkaloid pumiliotoxin B (8-hydroxy-8-methyl-6-alkylidene-1-azabicyclo[4.3.0]nonanes).

Pumiliotoxin B (PTX-B, 6-(6',7'-dihydroxy-2',5'-dimethyl-(E)-4'-octenylidene)-8-hydroxy-8 -methyl-1- azabicyclo-[4.3.0] nonane) increases the force of contractures of spontaneously beating guinea pig atrial strips by 3- to 5-fold with half-maximal effects at about 3 microM and increases rates of atrial contractions by 2- to 3-fold with half-maximal effects at about 6 microM. The presence of an axial 7-hydroxy substituent (PTX 339A) decreases the efficacy but not the potency of PTX-B as a positive inotropic agent while having only slight effects on activity as a positive chronotropic agent. The presence of an equatorial 7-hydroxy substituent (PTX 339B) greatly decreases efficacy and potency of PTX-B as a positive chronotropic and inotropic agent. Pumiliotoxin A which lacks the side-chain 7'-hydroxy group of PTX-B causes only a 2-fold increase in force of contracture at 54 microM while having minimal effects on rate. The presence of an axial 7-hydroxy substituent (PTX 323B' and 323B", epimeric at the 6'-hydroxy) markedly enhances positive inotropic and chronotropic effects of PTX-A. Another congener, PTX 251D with a 6-(2'-methylhexylidene) side chain, and a synthetic analogue with a 6-(6'-heptenylidene) side chain are cardiac depressants. Both lack hydroxyl groups in the side chain. The presence of an omega-1 hydroxy group in the side chain of PTX 251D yields an alkaloid (267C) with weak positive inotropic effects and minimal chronotropic effects. The presence of an axial 7-hydroxy group in the indolizidine ring of PTX 251D results in a compound (PTX 267A) with very weak positive inotropic effects while retaining the negative chronotropic effects of PTX 251D. A synthetic analogue with a 6-(7'-hydroxyheptylidene) side chain is a cardiac depressant even though it contains a side-chain hydroxyl corresponding in position to the 7'-hydroxyl of the side chain of PTX-B. The positive chronotropic and inotropic effects of pumiliotoxin B are reversed only by relatively high concentrations of the calcium channel blockers nifedipine and verapamil, suggesting that pumiliotoxin B may owe its cardiotonic activities to effects on internal mobilization of calcium.

Alkaloids↗
PubMed2001

Brain correlates of fast and slow handwriting in humans: a PET-performance correlation analysis.

The present study examined the cerebral control of velocity during handwriting. We employed H215O positron emission tomography (PET) to measure the regional cerebral blood flow (rCBF) in 10 healthy subjects. Participants were required to write the German verb 'bellen' ('to bark') either at their normal speed (i.e. fast open-loop handwriting) or to write at approximately half of their normal speed without visual feedback. The second task required a continuous modification of the motor output according to the kinaesthetic feedback from the hand (i.e. slow closed-loop handwriting). Pencil movements were recorded during PET scanning and analysed off-line using a stroke-based analysing program. The mean number of inversions in velocity (NIV) per stroke was used to quantify the mode of motor control during each PET scan. A NIV of 1 indicates fast open-loop processing, whereas an increase in NIV reflects a shift towards slow closed-loop processing of handwriting. Foci in the left primary sensorimotor cortex, the right lateral premotor cortex, the left anterior parietal cortex, the left anterior putamen, the left rostral supplementary motor area and the right precuneus showed a graded increase in functional activation with the mean NIV per stroke, suggesting that this set of brain regions is particularly involved in the processing of slow closed-loop writing movements. No area showed a negative relationship between rCBF and the mean NIV per stroke, suggesting that fast open-loop handwriting is achieved by an optimized cooperation of the manual sensorimotor network rather than by a selective activation of a distinct network component.

Adult↗
PubMed2002

Cyclin A correlates with carcinogenesis and metastasis, and p27(kip1) correlates with lymphatic invasion, in colorectal neoplasms.

Cyclin A binds to CDK2 and plays critical roles when cells proliferate; staining for Ki67 can monitor the proliferation. The cyclin A expression pattern remains unclear in colorectal carcinogenesis and remote metastasis, however, and no one has reported on the association of its expression with key clinicopathologic factors in primary cancer. p27(kip1) protein-an extremely important inhibitor of CDK2-seems unchanged as colorectal cancers metastasize to the lymph nodes, a result contrary to that seen in gastric and prostatic cancers. To clarify the role of cyclin A in multistage colorectal neoplasms, cyclin A, CDK2, and Ki67 were immunohistochemically stained in 22 normal mucosa, 9 hyperplastic polyps, 61 adenomas, 197 primary carcinomas, 21 lymph node metastases, and 10 hepatic metastases. To clarify the alteration of p27(kip1) during lymphatic invasion, p27(kip1) was also stained in 21 primary cancers and paired lymph node foci. Situated in nuclei, cyclin A expression gradually increased from mild through moderate to severe dysplasia in adenomas and from normal tissue through hyperplasia to adenoma to early carcinoma. Expression was significantly decreased in the hepatic metastases and in the primary cancers showing venous invasion, deep infiltration, lymph node metastasis, mucinous type, advanced stage, or short postoperative survival time. Elevated cyclin A not only was linked with elevated CDK2 in primary cancers, but also was associated with increased Ki67 in both adenomas and primary carcinomas. Lymph node metastases lost more p27(kip1) than primary foci and hepatic lesions. Thus, dysregulation of cyclin A and its control mechanisms may contribute to colorectal carcinogenesis; abatement of overexpression of cyclin A is associated with hepatic metastasis and cancerous invasion. Loss of p27(kip1) may promote lymph node metastasis.

Aged↗
PubMed2000

N-ras mutation in poorly differentiated thyroid carcinomas: correlation with bone metastases and inverse correlation to thyroglobulin expression.

Codon 61 of the N-ras oncogene was screened for mutations in 99 surgically resected thyroid carcinomas by a polymerase chain resection (PCR)-based method (PCR-primer introduced restriction with enrichment of mutant alleles [PCR-PIREMA]). A point mutation of the N-ras oncogene at the codon 61 was detected in 16 of 99 (16.2%) thyroid carcinomas examined by this method. No RAS alteration was detected in the group of 11 medullary thyroid carcinomas, while 3 of 31 (10.0%) papillary carcinomas, 2 of 5 (40%) follicular carcinomas, 8 of 44 (18.2%) poorly differentiated carcinomas, and 3 of 5 (60%) undifferentiated carcinomas showed an activation of N-RAS proto-oncogene. Interestingly, two primary follicular tumors and their corresponding bone metastases, showed N-ras mutations. In the same cases we evaluated the expression of thyroglobulin by immunohistochemical analysis. Although the majority of well-differentiated carcinomas expressed a high level of thyroglobulin, the expression of the same antigen was absent or only occasional weakly positive in 33 of 44 poorly differentiated carcinomas. Interestingly, N-ras mutation was restricted to the group of tumours with low or absent thyroglobulin expression, suggesting that this genetic change is prevalent in less differentiated tumors.

Bone Neoplasms↗