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Biomedical subjects

R Love

Publications and source records attributed to R Love.

At least 55 records · Page 3Linked to original sources
PubMed1977

Interaction of membrane aminophospholipids of E. coli with fluorodinitrobenzene and trinitrobenzenesulfonate.

E. coli cells were reacted with TNBS in bicarbonate-NaCl buffer, pH 8.5 (buffer A) and in phosphate-NaCl buffer, pH 7.0 (buffer B). In buffer A, DNP-GPE is the major product when FDNB is used. DNP-PE and DNP-LPE are formed in lesser amounts. Phospholipase A activity is high in buffer A. When TNBS is used, the labeling of the lipid components is less than with FDNB and more TNP-PE is formed relative to TNP-GPE. This data suggests that the phospholipases which are located primarily on the outer L-membrane of the cell wall act to a lesser extent on TNP-PE than on DNP-PE. E. coli cells were prelabeled with TNBS and FDNB in buffer A, washed and incubated in buffer A. The endogenous labeled DNP-PE gradually decreased with time with a concomitant increase in DNP-LPE and DNP-GPE due to phospholipase A activity. In contrast, the endogenous labeled TNP-PE also decreased with time as did the endogenous labeled TNP-LPE but a new orange lipid was produced. This lipid is believed to be a derivative of TNP-PE in which one of the nitro groups has been reduced to an amino group by nitroreductase. E. coli cells were prelabeled with TNBS and FDNB in buffer A, washed and incubated in buffer B. Under these conditions with both TNBS and FDNB there is an increase in TNP-PE and DNP-PE with a concomitant decrease in TNP-LPE, TNP-GPE, DNP-LPE and DNP-GPE. These results show that at neutral pH acylation occurs to regenerate TNP-PE and DNP-PE. E. coli cells were incubated with exogenous DNP-GPE or TNP-GPE in buffer A. The DNP-GPE and TNP-GPE were rapidly hydrolyzed by a phosphodiesterase to DNP-ethanolamine and TNP-ethanolamine. An orange derivative was formed which was provisionally identified as a derivative of DNP-ethanolamine or TNP-ethanolamine in which a nitro group has been reduced to an amino group by nitroreductase. The phospholipases and acylating enzymes present in the cell wall of E. coli are active on the dinitrophenyl and trinitrophenyl derivatives of PE and LPE and may act in concert to model and repair the plasma membrane.

Binding Sites↗
PubMed1977

Factors in the pathomechanism of chronic lymphocytic leukemia.

It has been shown that CLL is characterized by a piling up of highly differentiated lymphocytic cells. These cells have the structural and metabolic characteristics of a neoplastic cell line of B lymphocytes (except in cases of "T-cell CLL"). However, they lack the immunoglobulin-secreting ability of normal B cells, and are immunologically incompetent and inert. Next to this population, there is a normal but reduced population of B cells and a periodically slightly increased T-cell population. The accumulation of pathological cells is based on a 10-fold increase in proliferation of cells that have a 5-fold increase in their life span. In addition, there is a disturbance of exchange of cells between the intra- and extravascular pools. These characteristics clarify the development of the clinical picture: through packing of the bone marrow with pathological cells on the one hand, and the spleen on the other, anemia, thrombocytopenia, and finally granulocytopenia develop. The gradual displacement of normal B cells often leads to extreme hypogammaglobulinemia as the main component of a multifactorial syndrome of immune deficiency.

Animals↗
PubMed1977

Upper alveolar carcinoma--a 30 year survey.

Primary malignancy of the upper alveolus is an infrequent type of intra-oral carcinoma. This study reviews in detail 50 patients with a primary tumor of the upper alveolus who were treated at the Cancer Control Agency of British Columbia and Vancouver area hospitals, between 1940-1970 inclusive. Sixteen per cent had exposure to possible industrial carcinogens; 34 per cent had previous leukoplakia. The common presenting symptoms were pain (78 per cent) and swelling (64 per cent). Only 22 per cent had tumors confined to the upper alveolus. Fifty-two per cent had extensive lesions (i.e. T3 and T4). Twenty-six per cent had palpable cervical lymph nodes with potential metastatic disease. Treatment consisted of surgery, radiotherapy, or a combination of both. Complications are detailed. The five year survival rate is 44 per cent; and the 10 year survival rate 24 per cent. Treatment rationale is discussed.

Aged↗
PubMed1976

Chemical synthesis of dinitrodiphenysulfone derivatives of ethanolamine and serine and its application to the study of neighbor analysis of amino-phospholipids in the erythrocyte membrane.

The dinitrodiphenysulfone derivatives of serine and ethanolamine have been prepared and their chromatographic and spectral properties are described. This cross-linking agent was used to determine the neighbor analysis of amino-phospholipids in the erythrocyte membrane. The results with erythrocyte ghosts show that at 50 muM probe 31-50% of the total phosphatidylethanolamine is cross-linked to itself and 10-12% of the phosphatidylethanolamine is cross-linked to phosphatidylserine. Approximately 10-12% of the phosphatidylserine is cross-linked to itself and 16-20% of phosphatidylserine is cross-linked to phosphatidylethanolamine. The cross-linking of amino-phospholipids of ghosts with difluorodinitrodiphenylsulfone (9 A span) is compared with cross-linking of these phospholipids by difluorodinitrobenzene (5 A span). It is important to use the same sample of ghosts for this type of study since biological variability was seen in ghosts prepared from different batches of stored blood.

Dinitrofluorobenzene↗
PubMed1976

Differential reaction of cell membrane phospholipids and proteins with chemical probes.

The major aims of this study were to determine the degree of phospholipid asymmetry and the neighbor analysis of phospholipids in different types of cell membranes. For this study a penetrating probe (FDNB), a non-penetrating probe (TNBS) and a cross-linking probe (DFDNB) were used. The reaction of hemoglobin, membrane protein and membrane PE and PS of erythrocytes with DFNB and TNBS was studied over a concentration range of 0.5 to 10 mM probe. TNBS reacts to an extremely small extend with hemoglobin over the concentration range 0.4 to 4 mM whereas FDNB reacts with hemoglobin to a very large extent (50 fold more than TNBS). The reaction of membrane protein of intact erythrocytes reaches a sharp plateau at 1 mM TNBS whereas the reaction of membrane protein goes to a much larger extent with FDNB with no plateau seen up to 4 mM FDNB. This data shows that TNBS does not significantly penetrate into the cell under our conditions whereas FDNB does penetrate into the cell. The results show that there are four fold more reactive sites on proteins localized on the inner surface of the erythrocyte membrane as compared to the outer surface. TNBS at 0.5 to 2 mM concentration does not label membrane PS and labels membrane PE to a small extent. The reaction of PE with TNBS shows an initial plateau at 2 mM probe and a second slightly higher plateau between 4 to 10 mM probe. TNBS from 0.5-2.0 mM does not react with PS, but between 3 to 10 mM concentration, a very small amount of PS reacts with TNBS. Hence above 2 mM TNBS or FDNB a perturbation occurs in the membrane such that more PE and PS are exposed and react with these probes. These results demonstrate that essentially no PS is localized on the outer surface of the membrane and only 5% of the total membrane PE is localized on the outer surface of the erythrocyte membrane. TNBS and FDNB were reacted with yeast, E. coli, and Acholeplasma cells. With yeast cells, FDNB reacts to a much larger extent with PE than does TNBS, indicating that FDNB penetrates into the cell and labels more PE molecules. With E. coli, but not with erythrocytes or yeast cells, phospholipase A activity was very pronounced at pH 8.5 giving rise to a large amount of DNP-GPE from DNP-PE. A phosphodiesterase was also present which hydrolyized DNP-GPE to DNP-ethanolamine. The multilayered structure of the E. coli cell envelop did not permit a definitive interpretation of the results. It is clear, however, that TNBS and FDNB react to a different extent with PE in this cell. The Acholeplasma membrane had no detectable PE or PS but contains amino acid esters of phosphatidylglycerol. The reaction of these components with TNBS and FDNB indicate that these aminoacyl-PG are localized on both surfaces of the membrane, with 31% being on the outer surface and 69% on the inner surface...

Binding Sites↗
PubMed1976

Reaction of amino-phospholipids of the inner mitochondrial membrane with fluorodinitrobenzene and trinitrobenzenesulfonate.

Mitoplasts from rat liver mitochondria and ETPH particles from beef heart mitochondria were reacted with TNBS and FDNB in sucrose-mannitol-bicarbonate buffer pH 8.2 (BUFFER A) and in sodium chloride-bicarbonate buffer pH 8.5 (buffer B). Mitoplasts and ETPH particles are more stable in buffer A and very little hydrolysis of phospholipids occurs during the reaction period. In this buffer TNBS reacts to a lesser extent with phosphatidylethanolamine (PE) than does FDNB. The data suggests that with mitoplasts 65% of the total PE is localized on the outer surface of the membrane. With mitoplasts the labeling of membrane proteins is much more extensive with FDNB and suggests that 66% of the proteins are localized on the inner membrane surface. Thus a dual type of asymmetry occurs in the mitoplast membrane with more PE localized on the outer surface and more protein localized on the inner surface. In buffer B, extensive degradation of the dinitrophenylated and trinitrophenylated PE and LPE occurs to yield DNP-GPE and TNP-GPE respectively. DNP-GPE and TNP-GPE are degraded by a phosphodiesterase to DNP-ethanolamine and TNP-ethanolamine. When ETPH particles are labeled with TNBS and FDNB, washed, and incubated in buffer A and buffer B, a resynthesis of TNP-PE and DNP-PE occurs in buffer A by acylation of TNP-LPE whereas DNP-PE continues to be formed, primarily from DNP-GPE. These studies provide evidence for an asymmetric arrangement of PE in the inner mitochondrial membrane and demonstrate the presence of membrane-bound phospholipases which act on dinitrophenylated and trinitrophenylated amino-phospholipids. A membrane bound phosphodiesterase is also present which degrades dinitrophenylated or trinitrophenylated GPE. The degradative reactions prevail in bicarbonate-NaCl buffer B whereas acylation reactions prevail in sucrose-mannitol buffer A.

Animals↗
PubMed1976

Isonucleolinosis in cell cultures of human meningiomas.

In cell cultures of 13 human meningiomas the internal structure of the nucleolus was stained by the toluidine blue-molybdate method and compared with the karyotype of the tumors. Although some of the meningiomas had lost or gained one or more chromosomes and had undergone structural aberrations, all of them showed isonucleolinosis, which is normally found only in cells with normal karotype. It seems possible that the occurrence of iso- or anisonucleolinosis is not a specific sign of euploidy or aneuploidy, but of benignity or malignancy of the examined tissue.

Cell Nucleolus↗
PubMed1975

The reaction of chemical probes with the erythrocyte membrane.

Trinitrobenzenesulfonate (TNBS), fluorodinitrobenzene (FDNB) and suberimidate have been reacted with intact human erythrocytes. TNBS does not penetrate the cell membrane significantly at 23 degrees C in bicarbonate-NaCl buffer, pH 8.6, as estimated by the labeling of the N-terminal valine of hemoglobin. Hence, under these conditions it can be used as a vectorial probe. However, at 37 degrees C, especially in phosphate buffer, at pH 8.6, TNBS does penetrate the cell membrane. FDNB and suberimidate both penetrate the erythrocyte membrane. The time course reaction of TNBS with intact erythrocytes over a 24-hr period at 23 degrees C is complex and shows transition zones for both membrane phosphatidylethanolamine (PE) and membrane proteins. No significant cell lysis occurs up to 10 hr. The fraction of total PE or phosphatidylserine (PS) which reacts with TNBS by this time period can be considered to be located on the outer surface of the cell membrane. Under these conditions it can be located on the outer surface of the cell membrane. Under these conditions it can be shown that 10 to 20% of the total PE and no PS is located on the outer surface of the membrane and hence these amino phospholipids are asymmetrically arranged. The pH gradient between the inside and outside of the cell in our system is 0.4 pH units. Nigericin has no effect on the extent of labeling of PE or PS by TNBS. Isotonic sucrose gives a slight enhancement of the labeling of PE by TNBS. Hence, the inability of PE and PS to react with the TNBS is considered not due to the inside of the cell having a lower pH. The extent of reaction of TNBS with PE is not influenced by changing the osmolarity of the medium or by treatment of cells with pronase, trypsin, phospholipase A or phospholipase D. However, bovine serum albumin (BSA) does protect some of the PE molecules from reacting with TNBS. Cels treated with suberimidate were suspended in either isotonic NaCl or in distilled water. In both cases the suberimidate-treated cells became refractory to hypotonic lysis. Pretreatment of cells with TNBS did not prevent them from interacting with suberimidate and becoming refractory to lysis. However, pretreatment of cells with the penetrating probe FDNB abolished the suberimidate effect. Electron-microscopic analysis of the cells showed a continuous membrane in the case of cells suspended in isotonic saline. The cells suspended in water did not lyse but their membranes had many large holes, sufficient to let the hemoglobin leak out. Since the hemoglobin did not leak out we know that the hemoglobin is cross-linked into a large supramolecular aggregate.

Benzenesulfonates↗