Multilamellar packing of myelin modeled by lipid-bound MBP

Membrane compaction and adhesion at the major dense line (cytoplasmic apposition) of myelin, particularly in the central nervous system (CNS), is typically attributed to myelin basic protein (MBP). To explore the role of MBP in myelin membrane adhesion, we attempted to reconstitute the major dense line of myelin from purified lipid-bound MBP, which is a detergent-soluble form of MBP that retains the binding of all the myelin lipids. Removal of detergent by long-term dialysis yielded a precipitate, which, when analyzed by sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) and thin-layer chromatography, contained MBP that was still associated with myelin lipids, but in different proportions than in the native membrane. Comparison of lipid composition among isolated myelin, MBP-free myelin lipids, and lipid-bound MBP aggregates showed that the lipid-bound form of the protein was specifically enriched in phosphatidylethanolamine, phosphatidylcholine, sphingomyelin, phosphatidylinositol, and phosphatidylserine. Electron microscopy and x-ray diffraction demonstrated that the lipid-MBP complexes formed multilayers having periods of 70-85 A, which correspond in width to individual myelin membranes. By contrast, the lipids alone assembled as multilayers having a period of approximately 40 A. Thus, the detergent-soluble form of MBP, which is bound to lipids, might serve as a simple model for the cytoplasmic apposition of myelin.

Hypericin photosensitization of tumor and metastatic cell lines of human prostate

We have investigated the photoactivating effect of hypericin on two cancer cell lines: PC-3, a prostatic adenocarcinoma non-responsive to androgen therapy and LNCaP, a lymphonodal metastasis of prostate carcinoma responsive to androgen therapy. The two cell lines are incubated for 24 h with hypericin at concentrations ranging from 0.001 to 0.3 microg/ml in cell culture medium. The cells are irradiated at 599 nm (fluence = 11 J/cm2) using a dye laser pumped by an argon laser. Hypericin exerts phototoxic effects on both cell lines, while it does not produce toxic effects in the absence of irradiation. These results suggest that photodynamic therapy (PDT) with hypericin could be an alternative approach to the treatment of prostatic tumors, and could be beneficial in tumors that are non-responsive to androgen therapy.

Changes of serum sICAM-1 and MMP-9 induced by rIFNbeta-1b treatment in relapsing-remitting MS

OBJECTIVE

To correlate changes in serum levels of intercellular adhesion molecule-1 (sICAM-1) and matrix metalloproteinases (MMP) with clinical and MRI evidence of disease activity in MS patients receiving treatment with interferon-beta (rIFNbeta)-1b.

BACKGROUND

rIFNbeta reduces the frequency of gadolinium-enhancing (Gd+) MRI in relapsing-remitting MS (RRMS). Its mechanism of action on improving the integrity of the blood-brain barrier remains unclear.

METHODS

sICAM-1 and MMP-9 and MMP-2 serum levels were longitudinally (24 months) investigated (ELISA; zymography) in correlation with the modifications of the integrated area under the curve of Expanded Disability Status Scale scores normalized to entry baseline (deltaEDSS AUC) and of GD+ MRI scans, and with neutralizing antibodies (NAB) to rIFNbeta-1b production (MxA) in 36 RRMS patients.

RESULTS

During the first 12 months of treatment, levels of sICAM-1 increased and MMP-9 decreased significantly. After 12 months, levels returned toward baseline. Levels of sICAM-1 and MMP-9 were significantly negatively correlated. MMP-2 levels did not change significantly during the same period. During the second semester of the study, deltaEDSS AUC was significantly reduced. The percentage of patients with Gd+ MRI decreased significantly in the first (33%), second (29%), third (20%), and fourth (28%) semesters of treatment compared to baseline (62%). The NAB+ patients (14%) tended to have lower sICAM-1 levels at the ninth month; a higher MMP-9 activity at the sixth, 12th, and 18th months; and a greater deltaEDSS AUC in the third semester of treatment in comparison with the NAB- patients.

CONCLUSIONS

These results show that rIFNbeta-1b therapy increases sICAM-1 serum levels and reduces serum MMP-9 activity.

Conformation of bovine myelin basic protein purified with bound lipids

The basic protein of myelin (called MBP) is an extrinsic protein of the myelin membrane. Its structure and function are still unknown. MBP has been extensively studied in its water-soluble form, but it is also known in a detergent-soluble form, which is purified with endogenous myelin lipids and should correspond to the native form of the protein in the membrane. In order to acquire insight into the structure of MBP, we have carried out circular dichroism (CD) experiments on the protein both in the lipid-free and in the lipid-bound form. Our data clearly show that lipid-free MBP is mainly disordered with only a small amount having alpha-helix and beta-sheet motifs. On the other hand, the lipid-bound form of MBP appears to have a consistent amount of ordered secondary structure. Theoretical predictions, made using different computational methods, substantially confirm the tendency of the protein to assume an ordered secondary structure in accordance with our CD results.

Regulation of gelatinases in microglia and astrocyte cell cultures by plant lectins

The effects of 25 recently discovered plant lectins on cell proliferation and enzyme release were compared to those of previously known lectins on rat microglia and astrocyte cell cultures. A dose-dependent proliferation of microglial cells, but not of astrocytes, was induced by seven lectins, whereas five lectins showed dose-dependent cytotoxicity on both microglia and astrocyte cell cultures. The activity of gelatinase B (MMP-9) was strongly increased in microglial cells by the aforementioned seven lectins, by concanavalin A, and by phytohemagglutinin (PHA-E4), whereas gelatinase A (MMP-2) remained at constitutive levels. The five cytotoxic lectins decreased the activity of gelatinase B in microglia and of gelatinase A in astrocytes, in a dose-dependent manner. The lectin wheat germ agglutinin induced a decrease in gelatinase B activity in microglia, but stimulated gelatinase A and B activity in astrocytes. These results indicate that lectins possess neuromodulatory effects that may motivate the study of their effects on central nervous system (CNS) function in vivo. This, in turn, may lead to better insight into whether lectin or lectin-like molecules can interact with glial cells, and whether they have a role in acute toxicity and in multifactorial diseases in which environmental factors may play a role.

[Family dynamics: sleep quality of women caregivers of family members with Alzheimer disease]

This replication study/Riccio 1996) sets out to explore the Quality of sleep of 34 women primary caregivers of Alzheimer's Disease patients at home. A descriptive, correlational and longitudinal design has been used. Key aspects considered were the quality of nocturnal sleep, the daytime sleepiness, the hours of caring, the educational level, the employment, the time for personal needs and the levels of depression and anxiety. After an initial interview, the caregivers were asked to fill in several instruments to measure the variables taken into consideration. The caregivers presented poor quality in their sleep. Quality of nocturnal sleep was negatively affected by more hours of caring (p < 0.02), high depression and anxiety levels (p < 0.05 and 0.007 respectively). The education level, the employment outside home and the amount of time spent for themselves, positively affected the quality of sleep (p < 0.01, 0.04, 0.05 respectively). This research pointed out that hours of caring, directly and indirectly, cause sleep problem to Alzheimer's Disease caregivers enhancing nursing care implications.

Purification of bovine P2 myelin protein with bound lipids

The P2 protein is a neuritogenic, small basic protein present in PNS myelin. It belongs to the family of the cytoplasmic lipid-binding proteins and can be incorporated in lipidic bilayers. P2 has been purified and crystallized only in the lipid-free form. Here we show that the P2 protein can be purified with bound lipids by applying to PNS myelin the same procedure that as used to purify lipid-bound myelin basic protein from CNS myelin. SDS-PAGE showed a single band of 16.5 kDa, and TLC showed the presence of most of the myelin lipids associated with the protein. Lipid-bound P2 revealed different circular dichroism spectra from the corresponding lipid-free form, indicating that lipids influence P2 conformation.

HLA-DR-restricted presentation of purified myelin basic protein is independent of intracellular processing

Antigen presentation to CD4+ T cells involves intracellular antigen processing and loading of peptides onto newly synthesized major histocompatibility complex (MHC)-class II molecules. Some antigens, such as the lipid-bound, native form of myelin basic protein (LB-MBP) can also be presented by recycling of cell surface MHC class II molecules. The data reported here demonstrate that a preparation of highly purified, delipidated MBP (HP-MBP) follows yet another presentation pathway. Similar to LB-MBP, presentation of HP-MBP to HLA-DR1-restricted T cells was independent of HLA-DM, of newly synthesized proteins, and of invariant chain expression. However, in contrast to LB-MBP, presentation of HP-MBP was also independent of internalization of surface HLA-DR molecules. The different requirements for the presentation of the two molecular forms of MBP were further confirmed by use of the protease inhibitor E64: presentation of LB-MBP but not of HP-MBP was inhibited after treatment of target cells with E64. Furthermore, intact HP-MPB bound to isolated HLA-DR molecules in vitro with an association rate that was considerably faster than that of short peptides. These results show that presentation of HP-MBP is independent of intracellular processing and suggest that it may be presented to T cells by direct binding to surface HLA-DR molecules.

In vitro photo-activation of newly synthesized chlorin derivatives with red-light-emitting diodes

We investigated the in vitro photo-activation properties of two chlorin derivatives, i.e. 8-cis-heptylchlorin dicarboxylic acid and 3-trans-heptylchlorin bisamidoglucose derivative, which exhibit lipophilic properties similar to those of the active fractions of Photofrin II, on a normal epithelial cell line (FRTL-5). We used as an irradiation source an array of diodes emitting red light (lambda = 675 nm), which produced a fluence of 7mW cm-2 on the cells. We found that photo-activation with chlorin derivatives in the concentration range 1-100 ng ml-1 greatly enhanced the mortality of the irradiated cells (energy density, 0.25 J cm-2) with respect to the control cells kept in the dark. This response is immediate and appears to be an "all or none' effect. Taking into account that compounds exhibit a strong absorbance peak in the long wavelength region of visible light where tissues are relatively transparent, our results suggest that chlorins can be considered to be good candidates for application in photodynamic therapy.

Different recognition by clostripain of myelin basic protein in the lipid-free and lipid-bound forms

Different proteolytic enzymes were tested for their ability to degrade the myelin basic protein of the central nervous system, purified in two different forms, the lipid-free form and the lipid-bound form. As shown by SDS gel electrophoresis only clostripain, a thiol protease, was able to distinguish between the two MBPs since it degraded MBP only in the lipid-free form. The failure to degrade lipid-bound MBP by clostripain could not be ascribed to the presence of lipids, since the other proteolytic enzymes tested degraded both MBPs independently from lipids giving fragments with different size. These results may be related to different conformations of MBPs possibly relevant for the study of myelin structure and antigenic properties of the protein.

Kinetic transport analysis of daunorubicin by LoVo and LoVo/DX cells

We describe a fluorometric technique for the measurement of transport parameters of fluorescent drugs through cellular membranes. Unlike other procedures, this method gives an accurate measure of drug accumulated in the cells and measures the fraction of free and bound drug in the cell. The kinetic parameters of transport through cellular membranes are determined using a simple three-compartment model combined with fluorescence measurements performed on the extracellular medium and on Triton-permeabilized cells during daunorubicin incorporation. With this technique we found that LoVo cells have a greater daunorubicin uptake, a similar input rate constant and a lower output rate constant than the drug-resistant LoVo/DX cells.

Prognostic significance of nucleolar organizer regions in meningiomas

The argyrophilic method for the demonstration of nucleolar organizer region-associated proteins (AgNOR's) was applied to paraffin-embedded histologic sections of 30 meningiomas. These were divided into three groups: 1) group I comprising 10 primary tumors which subsequently recurred within five years; 2) group II including the relative recurrences of the above mentioned primary tumors; 3) group III consisting of 10 nonrecurrent tumors over a follow-up of at least five years. The means of AgNOR counts were 1.58 with a SD of 0.67 for the group I, 1.47 with a SD of 1.04 for the group II, and 1.42 with a SD of 0.62 for the group III. A statistical analysis of these data using the Student's "t" test showed no significant difference between primary tumors and relative recurrences, as well as between primary and nonrecurrent tumors. However, when the AgNOR number was > 2.0 there was a statistically significant difference between primary and nonrecurrent meningiomas. These results are discussed in light of the findings previously reported by the literature.

Release of myelin basic protein-degrading proteolytic activity from microglia and macrophages after infection with Theiler's murine encephalomyelitis virus: comparison between susceptible and resistant mice

Theiler's murine encephalomyelitis virus (TMEV) produces a chronic inflammatory demyelinating disease in its natural host, the mouse. A delayed-type hypersensitivity (DTH) response to viral antigens generally correlates with susceptibility to the disease and is thought to play an important role in the pathogenesis of demyelination in this model of human multiple sclerosis (MS). The hallmark of DTH responses is the recruitment by activated Th-1 cells of lymphoid cells and especially macrophages in infected areas. It is believed that soluble factors released by these cells would produce tissue damage, particularly myelin breakdown. In the present study, we compared TMEV-infected macrophages and microglia, isolated from both susceptible SJL/J and resistant C57BL/6 mice, for their ability to secrete proteolytic enzymes capable of degrading myelin basic protein. In addition, we studied whether supernatants from infected microglia/macrophages were also capable of killing oligodendrocytes in the same in vitro system. As detected by SDS-PAGE, MBP-degrading proteolytic activity was found only in supernatants from infected SJL/J microglia and macrophages, but not in supernatants collected from infected C57BL/6 microglia and macrophages, or in supernatants from mock-infected SJL/J and C57BL/6 cells. Similarly, incubation of E20.1 cells, an immortalized line of oligodendrocytes, with infected SJL/J, but not C57BL/6 supernatants, resulted in cytotoxic activity. When cells from resistant C57BL/6 mice were treated with LPS, they became susceptible to infection and also secreted proteolytic enzymes. The proteolytic activity released from infected microglia and macrophages was found to be dose-dependent, was inactivated by heat, and was inhibited by phenylmethylsulphonyl fluoride (PMSF). These results indicate that a serine protease is released from infected microglia and macrophages and suggest a role for proteases in TMEV-induced myelin injury.

Specificity of zinc binding to myelin basic protein

Zn2+ appears to stabilize the myelin sheath but the mechanism of this effect is unknown. In a previous report we have shown that zinc binds to CNS myelin basic protein (MBP) in the presence of phosphate and this results in MBP aggregation. For this paper we used a solid phase zinc blotting assay to identify which myelin proteins bind zinc. MBP and a 58 kDa band were found to be the major targets of 65Zn binding. Moreover, using fluorescence, light scattering and electron microscopy we investigated the binding of zinc and other cations to purified MBP in solution. Among the cations tested for their ability to interfere with the binding of zinc, the most effective were cadmium, mercury and copper, but only cadmium and mercury increased the scattering intensity, whereas MBP aggregation was not inhibited by copper ions. Thus, the effect of zinc on the formation of MBP clusters seems to be specific.

Myelin degrading activity in the CSF of HIV-1-infected patients with neurological diseases

Degradation of purified myelin basic protein (MBP) was studied by SDS gel electrophoresis after addition of CSF samples obtained from HIV-1-infected patients. An increase in MBP degradation was detected in patients with neurological complications, such as AIDS dementia complex (ADC) or progressive multifocal leukoencephalopathy (PML), when compared with patients with no neurological symptoms (NA) or with other neurological opportunistic infections (OI). In the ADC and PML patients, in addition to CSF proteolytic activity, an increase in CSF-MBP levels and presence of white matter lesions were also observed by neuroimaging (MRI). In other opportunistic infections of the brain, MBP levels but not anti-MBP proteolytic activity increased. Results suggest the involvement of proteases in the virus-induced demyelination.

Fluorochromes with long-lived fluorescence as potential labels for pulsed laser immunocytofluorometry: photophysical characterization of pyrene derivatives

An apparatus for laser-induced time-resolved fluorescence measurements, in conjunction with pyrene derivatives endowed with long-lived excited singlet states, was employed for immunocytofluorometric measurements. N-(1-pyrene)maleimide, 1-pyrenesulfonyl chloride and 1-pyreneisothiocyanate were conjugated with immunoglobulin, antimouse-IgG, and the fluorescence decays of both free and conjugated forms were investigated. Bi-exponential decays were obtained in all cases with time constants of the short-lived component in the range 3-4.7 ns and the long-lived one in the range 20-55 ns. Only the spectral distribution of the two components is essentially affected upon conjugation. The persistence of the long-lived component, well above the lifetime of autofluorescence, and of the antibody specificity, as shown by immunodiffusion tests, upon conjugation indicates that this technique could be advantageously adopted in immunocytofluorometry.

Laser photosensitization of cells by hypericin

Administering a light dose of 90 J/cm2 at 599 nm during incubation with hypericin to a highly differentiated normal epithelial cell line (FRTL-5), derived from Fisher rat thyroid, and to a neoplastic cell line (MPTK-6), derived from the lung metastases of a thyroid carcinoma induced in Fisher rats, produces cell kill at drug doses 1000 times lower than those necessary to cause the same mortality in the dark. The photocytocidal activity of this polycyclic quinone drug on neoplastic cells is superior to that of antitumor anthraquinone drugs, such as daunomycin and mitoxanthrone, and to the photosensitized antiviral activity previously reported for hypericin.

Myelin basic protein interaction with zinc and phosphate: fluorescence studies on the water-soluble form of the protein

The interaction of myelin basic protein (MBP) with zinc and phosphate ions has been studied by using the emission properties of the single tryptophan residue of the protein (Trp-115). The studies have been carried out by means of both static and time-resolved fluorescence techniques. The addition of either zinc to MBP in the presence of phosphate or phosphate to MBP in the presence of zinc resulted in an increase of fluorescence intensity and a blue shift of the emission maximum wavelength. Furthermore, a concomitant increase in the scattering was also detected. Anisotropy decay experiments demonstrated that these effects are due to the formation of MBP molecules into large aggregates. A possible physiological role for such interaction is discussed.

A new detergent to purify CNS myelin basic protein isoforms in lipid-bound form

We have previously shown that CNS myelin basic protein (MBP) can be purified in the lipid-bound, native-like form by using a procedure based on myelin solubilization with detergents at pH above 7, and on the filter-like use of hydroxyapatite to separate non-adsorbed MBP from other myelin proteins. Here, we report on the isolation of MBP in the zwitterionic detergent 3-((3-cholamidopropyl)dimethylammonio)-1-propane sulfonate (CHAPS), which does not interfere at 280 nm and can be removed by dialysis. This detergent appears to improve MBP purification and to be suitable for fluorescence and reconstitution studies that can be useful to understand both structure and function of MBP in its natural environment.

Fluorometric determination of the kinetics of anthracyclines uptake by cells

Fluorometric measurements on extracellular medium are shown to allow kinetic parameters of in vitro anthracycline uptake by cells to be calculated. The method provides influx and efflux rates, as well as the time dependence of both influx and efflux. It is applied to a normal thyroid epithelial cell line (FRTL-5) and a cell line (MPTK-6) derived from the lung metastases of a thyroid carcinoma exposed to daunorubicin at concentrations within the range of 250 to 1000 ng/ml. The results show that the number of cells influences the dependence of the kinetics upon the extracellular drug concentration and that the MPTK-6 cells are endowed with very efficient efflux mechanisms.

Induction of experimental autoimmune encephalomyelitis in rats and immune response to myelin basic protein in lipid-bound form

Encephalitogenic activity of myelin basic protein (MBP) isolated in a form retaining binding to all myelin lipids was tested in Lewis rats. Immunization with this new stable lipid-bound and native-like preparation (LB-MBP), induced experimental autoimmune encephalomyelitis (EAE) as intensively as the classical lipid free MBP (LF-MBP). During the course of the disease, high affinity specific response to LB-MBP and high frequency of LB-MBP specific precursors was observed in peripheral lymphoid organs, indicating that the disease occurred in presence of anti LB-MBP specific T-cell responsivity. Short term lines, generated from lymphocytes collected at the onset of the disease from LB-MBP immunized rats, showed a strong dose-dependent response to LB-MBP, but not to LF-MBP. The present data indicate that in rat, LB-MBP maintains encephalitogenic activity and induces expansion of a specific T-cell population. These data suggest also that LB-MBP is a new autoantigen that may be relevant in human diseases.

Enhanced response to daunomycin of normal, tumor and metastatic cell lines via drug photoactivation

We have compared the cytotoxicity of daunomycin in vitro to highly differentiated normal epithelial cells (Fisher rat thyroid cells, FRTL-5) and to two neoplastic cell lines, a thyroid carcinoma (TK-6) and its lung metastasis (MPTK-6). Whereas the cell lines are equally sensitive to the drug in the dark, if irradiated during incubation with daunomycin (86 J/cm2 at 488 nm), they become more and differently sensitive. Namely, the drug doses producing 50% mortality decrease by factors of about 22, 28 and 16 for FRTL-5, TK-6 and MPTK-6 cell lines, respectively. This result correlates with differences in drug uptake and resistance observed in the normal and neoplastic cell lines.

Antibodies specific for the lipid-bound form of myelin basic protein during experimental autoimmune encephalomyelitis

On the hypothesis that myelin basic protein isolated with surrounding lipids may constitute an autoantigen in demyelinating diseases, we studied the antibody response to the lipid-free and lipid-bound form of myelin basic protein during the course of experimental autoimmune encephalomyelitis induced in rats with either form of protein. Immunization with the lipid-bound form of myelin basic protein induced high titres of antibodies directed to the protein, accompanied by no antibodies to cerebroside 30 days after immunization. Antibodies specifically directed to the lipid-bound form of myelin basic protein were revealed after removal of antibodies recognizing the delipidated myelin basic protein. Anti lipid-bound myelin basic protein antibodies could already be detected at day 10 post-immunization, reaching a maximum at day 20 post-immunization. Demonstrations of antibodies entirely specific for the lipid-bound form of myelin basic protein suggests that this molecule may present epitopes not to be found in its already extensively studied primary structure, possibly the result of conformational changes following lipid binding.

Identification of water-soluble proteases in myelin preparations

Sodium chloride extracts obtained from purified bovine brain myelin were found to contain proteolytic activity capable of degrading isolated myelin basic protein as assessed by SDS gel electrophoresis. Using gels copolymerized with gelatin as substrate, two bands at about 54 and 117-125 KDa, respectively, were detected. Activity corresponding to the 54 KDa band was inhibited by zinc. Data presented in this article suggest that proteolytic activity can be released from the myelin sheath in water-soluble form and recognize MBP as substrate.

Cerebrospinal fluid myelin basic protein as predictive marker of demyelination in AIDS dementia complex

Myelin basic protein (MBP) was measured in cerebrospinal fluid (CSF) of patients with acquired immunodeficiency syndrome (AIDS) dementia complex (ADC) in order to investigate the degree of white matter destruction. Results show that increased CSF levels of MBP were detected in all patients with severe ADC (10/10) and, less often, in subjects with mild (2/7) or moderate dementia (7/16). No evidence of MBP-elevated concentration was observed in 14 human immunodeficiency virus (HIV)-seropositive subjects without neurological disorders and in nine HIV-seronegative controls. Our findings suggest that the measurement of CSF MBP concentration may represent a predictive marker of myelin injury and neurologic damage during the course of ADC.

On the spontaneous adherence of myelin basic protein to T lymphocytes

We have applied a double tagging system in order to study whether purified myelin basic protein is able to adhere to normal human peripheral T lymphocytes without the need to purify cells. Evaluation of myelin basic protein adherence to peripheral blood mononuclear cells was determined with biotinylated myelin basic protein and fluoresceinated avidin, and lymphocyte population was identified by the corresponding phycoerythrinated monoclonal antibody. The observed adherence of myelin basic protein to T lymphocytes was found to depend on protein conformation.

Detection of cerebrospinal fluid antibodies against myelin basic protein in patients with AIDS dementia complex

We evaluated cerebrospinal fluid (CSF) antibody levels against a lipid-free, denatured form of myelin basic protein (LF-MBP) in 11 patients with AIDS dementia complex (ADC) by using an enzyme-linked immunosorbent assay (ELISA). In 9 out of 11 patients, anti-LF-MBP antibody levels were significantly higher than those observed both in 15 human immunodeficiency virus (HIV)-infected patients without neurological disorders and in 9 anti-HIV-negative subjects affected by other neurological diseases. Furthermore, we followed up anti-MBP levels in 5 out of the 11 ADC patients and detected a strict relationship with the encephalopathy progression. At the same time, with the aim to detect early demyelinating events we investigated CSF antibody levels against a lipid-bound, native-like form of MBP (LB-MBP). Results did not show any significant difference between LF-MBP and LB-MBP in terms of antibody reactivity. The detection of anti-MBP antibodies in CSF may provide the opportunity to assess a diagnostic tool for discovering demyelinating lesions in ADC patients.

Enhancement of antitumor drug cytotoxicity via laser photoactivation

We investigate the efficacy of daunomycin, some imino- and amino-substituted daunomycin analogues and the disubstituted aminoanthracenedione, mitoxantrone, in photosensitizing short-term cell kill upon irradiation in the long wavelength visible range, during incubation of Fisher rat thyroid cells with the drugs. While all compounds exhibit similar cytocidal effects on our cell line, in the absence of irradiation, administering 86 J/cm2 at wavelengths either coincident or close to drug absorption peaks causes greater enhancement in cell mortality for the 4-demethoxydaunomycin analogues than either the parent drug or its 5-imino-derivative. A lower enhancement is observed with mitoxantrone. In particular, C50 doses (i.e. concentrations that would kill 50% cells) as low as approximately 10(-9) M are found for both 6- and 11-amino 4-demethoxydaunomycin, compared with the values obtained in the absence of light, which are 2.59 x 10(-4) and 0.43 x 10(-4) M, respectively. Our previous studies of the photophysical and photochemical properties of the excited states of these drugs, and ESR and spin trapping studies of photosensitized generation of singlet oxygen, which were extended in this work to include mitoxantrone, indicate that the cytocidal effects proceed via type I rather than type II mechanisms.

Purification of lipid-associated basic protein from guinea pig spinal-cord myelin

Myelin basic protein (MBP) was purified from guinea pig spinal-cord in a native-like form retaining the binding to all the myelin lipids. Since the guinea pig MBP was found to be much more labile than the corresponding MBP from bovine brain, the original procedure based on the use of hydroxyapatite and detergents was slightly modified as reported here. The product of this purification, lipid-bound MBP, may represent an alternative to lipid-free MBP for the induction, the study and the treatment of experimental allergic encephalomyelitis.

Myelin basic protein in lipid-bound form induces experimental allergic encephalomyelitis and demyelination in Lewis rat

Myelin basic protein (MBP) was isolated from guinea-pig spinal cord in a form retaining the binding to all the myelin lipids. This new, lipid-bound and native-like preparation was used to immunize Lewis rats in complete Freund's adjuvant (CFA) in order to produce experimental allergic encephalomyelitis (EAE). The clinical features were compared with those of Lewis rats immunized with lipid-free MBP (LF-MBP), myelin, LF-MBP + octyl-POE (the non-ionic detergent used for the purification of LB-MBP) and octyl-POE alone. The clinical observation indicate that LB-MBP exerts an encephalitogenic activity on Lewis rats which is more intense than LF-MBP and includes demyelinating lesions in the central nervous system (CNS). The data suggest that LB-MBP is a new encephalitogenic antigen, which may induce more intensive immunization in rats and may be relevant in humans for autoimmune demyelinating diseases of the CNS.

Zinc as an inhibitor of myelin basic protein proteolytic breakdown in the central nervous system

It is known that central nervous system myelin contains proteolytic enzymes which degrade the myelin basic protein (MBP). We have found that zinc acetate is able to inhibit MBP cleavage at concentrations of 1 mM or higher. Furthermore, the Zn-inhibitable MBP-degrading activity was found to be water-soluble and able to recognize MBP also if this protein was protected by its lipidic environment in the native-like, lipid-bound form. Data presented here suggest a Zn-dependent metallo-protease which recognize MBP as a substrate probably even in the myelin sheath, when the protein is not yet released from the membrane.

Spontaneous adhesiveness of lipid-free myelin basic protein to immune cells as detected by a double labelling technique

We have investigated whether immunocompetent cells have the capacity to interact directly with the myelin basic protein (MBP) of the central nervous system. To this end we have applied a double tagging system in order to study whether purified lipid-free MBP is able to bind to normal peripheral blood mononuclear cells (PBMC) without the need to purify the cells. Evaluation of MBP binding to PBMC was determined with biotinylated MBP and fluoresceinated avidin, and lymphocytes population was identified by the corresponding phycoerythrinated monoclonal antibody (MoAb). The contemporary use of MoAbs and avidin unambiguously showed that MBP is able to bind to both B and T lymphocytes. The biological significance of MBP adherence to immune cells still needs clarification.

HIV-infection and in vivo lipopolysaccharide-induced release of cytokines. An amplified mechanism of damage to the host

Bacterial lipopolysaccharides (LPS) or endotoxins are potent triggers of the cytokine (CK) cascade. These CKs are immune mediators which produce many biological effects and could play a detrimental rather than beneficial role in the host. In this review emphasis will be placed on the participation of two CKs, tumor necrosis factor [TNF-alpha and interleukin (IL-1) beta], in the pathogenetic development of HIV infection. We have found that TNF and IL-1 circulate in exaggerated amounts in the blood of HIV-infected subjects from the earliest phases of infection. Furthermore, we have observed a strict correlation between plasma LPS and IL-1 beta levels, thus indicating that endotoxins could account for the production of CKs in the course of HIV infection. Finally, the demyelinating role of TNF-alpha either in experimental models or in the course of AIDS dementia complex is outlined.

Interaction of cations with lipid-free myelin basic protein. A spectroscopy study

The interaction of some divalent cations with myelin basic protein (MBP) in buffer and in model membranes was studied by using the static fluorescence of the intrinsic tryptophan residue of the protein. Results were indicative of Zn++ ability to bind to MBP. The observed binding could facilitate the interaction of MBP with lipids and have a role in stabilizing the myelin sheath.

Lipid-bound, native-like, myelin basic protein. Batch-wise preparation and perspectives for use in demyelinating diseases

Batch purification of the myelin basic protein (MBP) in the lipid-bound form was obtained from bovine brain white matter by using the slightly polydisperse nonionic detergent, n-octyl-pentaoxyethylene (octyl-POE) and hydroxyapatite. This large-scale procedure can also be carried out in laboratories without chromatographic equipment, and is applicable to small amounts of myelin. More interestingly, removal and inhibition of the proteolytic activity associated with myelin allowed us to obtain more stable and intact forms of the protein when compared with MBP isolated in the lipid-bound form by our previous method. Since it retains binding to all myelin lipids, this purified MBP may be considered as being in a native-like form. In this article, we suggest why this more intact form of MBP could be used to advantage as an alternative to lipid-free, water-soluble MBP in the study, detection, and treatment of myelin damage in pathology.

Estimation of protein secondary structure from circular dichroism spectra: a critical examination of the CONTIN program

The computer program CONTIN uses the Provencher and Glöckner procedure to calculate protein secondary structure from circular dichroism spectra. We have tested this program with peptides and proteins in which unfolding was either induced by denaturing treatment or was already present. Results indicate that the program does not clearly discriminate between the ordered and the unordered states of a protein.

[Foreign bodies in the alimentary tract. Surgical treatment]

Gastro-intestinal foreign bodies are a by no means rare event in surgery and in the USA mortality is about 1500 people per annum. The surgical treatment of foreign bodies in the alimentary tract is reported here. Certain cases of voluntary ingestion in mental patients are reported, comparing personal experience with the data reported in the literature.