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Biomedical subjects

B Wolf

Publications and source records attributed to B Wolf.

411 records · Page 23Linked to original sources
PubMedDate not supplied

Mathematical model for agonist-induced oscillatory calcium waves in non-excitable mammalian cells.

Many non-excitable cells display cytosolic Ca2+ oscillations resulting from the periodic release of Ca2+ from intracellular stores. Recent observations in hepatocytes and some other cell types have shown that agonist-induced Ca2+ oscillations often display an intracellular spatial organization and do not occur synchronously within the cell. Ca2+ waves evoked by different agonists originate from the same subcellular locus and propagate through the cell with a constant rate of progress and amplitude. This indicates that Ca2+ waves are driven by a self-propagating mechanism and not by diffusion alone. We propose a simplified one-dimensional mathematical model to describe this phenomenon based on the mechanism of calcium-induced calcium release. The numerical solution of the system of two coupled non-linear partial differential equations reproduces many of the main features observed experimentally.

Animals↗
PubMedDate not supplied

Cytosolic calcium oscillators: critical discussion and stochastic modelling.

In the last few years, an immense amount of experimental data on agonist-induced cytosolic Ca2+ oscillations has emphasized the necessity of theoretical models accounting for these phenomena. In the first part of the paper, a critical analysis of different minimal Ca2+ oscillator models is presented, which reveals that not all of the so far proposed mechanisms are capable to reproduce experimental data adequately. The second part of the paper is devoted to a computational method using a stochastic simulation algorithm which describes the time evolution of Ca2+ oscillations at the molecular level. In contrast to the deterministic formulation of the models presented so far, the stochastic treatment takes account of the inherent fluctuations of cytosolic Ca2+ in cellular subcompartments. In the macroscopic limit, the stochastic models display dynamics analogous to the deterministic ones.

Animals↗
PubMedDate not supplied

Comparative West Nile virus detection in organs of naturally infected American Crows (Corvus brachyrhynchos).

Widespread deaths of American Crows (Corvus brachyrhynchos)were associated with the 1999 outbreak of West Nile (WN) virus in the New York City region. We compared six organs from 20 crow carcasses as targets for WN virus detection. Half the carcasses had at least one positive test result for WN virus infection. The brain was the most sensitive test organ; it was the only positive organ for three of the positive crows. The sensitivity of crow organs as targets for WN virus detection makes crow death useful for WN virus surveillance.

Bird Diseases↗
PubMedDate not supplied

Differential patterns of drug involvement among Israeli youth.

The present study tries to link some demographic, social, psycholoogical and attitudinal variables of drug abuse. The findings were centred around the readiness of secondary school youth in Israel to be involved in drugs and their active searching for drug involvement. A dependent variable based on five indices of drug involvement was constructed. It was then related to parental control, peer involvement in drugs, sex differentiation and membership in youth movements. A bi-modal high involvement curve was found, the first mode consisting of youth of low socio-economic strata who are drop-outs, who associate with outside peer groups as an alternative to their shaky and diffused families and lack of involvement in school life. The other mode consists of youth with a higher socio-economic background who are involved with drugs due to their desire for new hedonistic and emotional experiences. Their openness to experiment with drugs is a corollary to their involvement within a peer group which condones and legitimizes narcotics as well as any experiences which irrespective of their source, provide "a good high". There is a sub-group within this group which would be involved with drugs as a partial escape from personal problems.

Adolescent↗
PubMedDate not supplied

An ultrastructural morphometric analysis of normal human mammary tissue and human breast cancer.

An ultrastructural morphometric study of normal and tumourous adult human mammary tissue is presented. The data show a characteristic numerical pattern for the different neoplastic stages of breast tissues. By applying a special data-comparison program a standardized diagnostic and prognostic system appears possible through the morphometric analysis of ultrathin epon sections of surgically obtained material.

Adenofibroma↗
PubMedDate not supplied

Ultrastructural localization of carcinoembryonic antigen (CEA) on ultrathin cryosections of human tumours.

A new, more direct method for reliable localization of CEA on human tumours has been applied at the ultrastructural level. Freshly prepared biopsy material from breast and gastric tumours, as well as xenografted colon tumours from mice, and a colon tumour cell line (LS 174 T), were briefly fixed in glutaraldehyde and frozen in liquid propane. Ultrathin cryosections were labelled with monospecific CEA antibodies by applying gold-coupled second antibodies. Variations in the labelling patterns were found when comparing breast, colon, and gastric cancers. Apart from breast tumours, all other samples reveal significant extracellular CEA positivity on the cell membrane. Intracellular localization has been found on the endoplasmic reticulum, nuclear membrane, and, in breast tumours, on electron dense bodies. These investigations confirm our previous experimental results using preembedding labelling techniques before Epon inclusion.

Biopsy↗
PubMedDate not supplied

Differentiation state specific localization of the carcino-embryonic antigen (CEA) on ultrathin cryosections of breast, stomach and lung lesions.

The ultraimmunohistochemical localization of carcinoembryonic antigen (CEA) in breast, gastric and lung tumours at various stages of differentiation showed that CEA is mainly located on well differentiated tumour cells, the subcellular morphometric data of which resembled more those of benign lesions rather than those of malignant tumours. All these cells were characterized by raised surface to volume ratios as compared to normal cells. The CEA labels were mainly found on the cell membranes, the outer nuclear membrane and the rough endoplasmatic reticulum (rER). Mono- and poly-clonal antibodies produced a similar labelling pattern, but the former appeared to have less affinity for glycocalix-associated structures than the latter.

Adenocarcinoma↗
PubMedDate not supplied

Ultrastructural morphometric studies on benign and malignant lung tumours.

Premalignant and malignant lesions from human lung tumours have been investigated by ultrastructural stereological methods and compared to normal bronchial tissue. It was possible to develop characteristic quantitative ultrastructural criteria for the different lesions. These criteria are the basic of a data bank system. After verification by further investigations they may be applicable to the development of a diagnosis supporting system.

Adenocarcinoma↗
PubMedDate not supplied

Improved surgical technique for carotid endarterectomy.

Despite improved results following carotid endarterectomy, a small but significant incidence of neurological deficit may follow the operation. Emphasis has deviated from the importance of the technical details of the operative procedure to consideration of the role of physiological factors (e.g., shunt, stump pressure, EEG vigilance, type of anesthesia). The surgical principles outlined in this report were used in a consecutive series of 214 patients undergoing carotid endarterectomy. A neurological deficit was noted in two patients (0.9%) in whom thrombosis of the repair site was proven.

Carotid Arteries↗
PubMedDate not supplied

Ultrastructural localization of carcino-embryonic antigen in a continuous human tumour cell line (LS 174 T) in relation to morphometric investigations.

The synthesis of carcinoembryonic antigen (CEA) in human tumour cell cultures has been investigated at the ultrastructural level in the colon carcinoma cell line LS 174 T. By application of a CEA-specific antibody fraction, gained from goat serum which was directly coupled with horse radish peroxidase (HRP), the expression of CEA could be followed in the cell culture both intra- and extracellularly with ultra-immunohistochemical methods, utilizing the pre-embedding technique. Morphometric and ultra-immunohistochemical investigations showed the possible involvement of the Golgi systems in CEA production. The changes in the volume fraction of the Golgi apparatus related to the total cell volume showed a direct correlation with the CEA content in the cell culture supernatants. Freeze-etch control experiments revealed negligible structural changes in the cells following ethyl-dimethyl-aminopropylcarbodiimide (EDC)-and saponin permeation techniques.

Adenocarcinoma↗
PubMedDate not supplied

Hypoxemia in attack free asthmatic children: relationship with lung volumes and lung mechanics.

In 113 asthmatic children (mean age +/- SD = 11.0 +/- 2.8 years), the presence of hypoxemia was evaluated during an attack free period. Blood gases were measured in arterialized blood samples. 71% of the patients were hypoxemic. Hypoxemia was defined as partial pressure of O2 (PaO2) below 90% of the mean value for normal children. In a first step, the relationship between hypoxemia and frequency of asthma attacks was examined: frequency of attacks appeared to be a poor predictor of hypoxemia in an attack free period. In a second step, the relationship between hypoxemia and 9 pulmonary function test variables was examined. The static lung volumes considered were: functional residual capacity (FRC: helium dilution technique); thoracic gas volume (TGV: body plethysmography technique) and trapped gases (TG: difference between TGV and FRC). TG was expressed as a percentage of 1) measured FRC (TG/FRCmeas), 2) measured TGV (TG/TGVmeas), 3) predicted FRC (TG/FRCpred). Lung mechanics variables were determined by the oesophageal catheter technique: lung resistance (RL) and dynamic lung compliance (CLdyn). RL and CLdyn were expressed 1) in absolute terms, 2) as a percentage of the index of distension (ID: TGV/FRCpred). All variables are expressed as a percentage of predicted values except for TG/FRCmeas and TG/TGVmeas. Considering lung volumes, hypoxemia was found when TG was present. When lung mechanics were altered, hypoxemia was also present. The relationship between PaO2 and PFT variables was best expressed by the following equation: PaO2 (%) = 85.393 + 0.121 CLdyn/ID--0.151 TG/FRCpred--0.026 RL.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Relevance of microenvironmental pH for self-organized tumor growth and invasion.

The process of tumor cell growth, invasion and metastasis involves a self-organized cascade of multiple tumor-host and tumor-immune interactions. The prediction of cancer development based exclusively on molecular evidence is still impossible because of the complex and heterogeneous control mechanisms actually acting in cellular systems. In contrast, most tumor cell systems display a limited spectrum of macroscopically observable modes of action which emerge as a result of cellular self-organization. The stability of the dynamic modes is controlled by relatively few order parameters. Their number and characteristics are different in normal and neoplastic growth. A systems-oriented analysis utilizing our method of Structured Biological Modelling (SBM) suggests that microenvironmental pH (pHme) can function as an important order parameter for self-organized cancer development. In the scope of an integrated minimal model for the multistep development of invasive tumor growth, this finding will be discussed with respect to its evolution, diagnostic relevance and possible therapeutical implications. The study underlines the necessity of minimal invasive methods for the on-line in vitro and in vivo monitoring of pH, oxygen, signal transducing molecules and essential nutrients in the microenvironment of tumor cells.

Cell Division↗