Search PubMed⌕ Search

Biomedical subjects

B Frisch

Publications and source records attributed to B Frisch.

At least 19 recordsLinked to original sources
PubMed2001

Enhancement of gene delivery by an analogue of alpha-MSH in a receptor-independent fashion.

In order to transfect melanoma specifically by receptor-mediated endocytosis we prepared dioctadecyl aminoglycylspermine (lipospermine)--DNA complexes with [Nle(4),D-Phe(7)]-alpha-MSH(4--10), a pseudo-peptide analogue of alpha-melanocyte stimulating hormone (alpha-MSH) linked to a thiol-reactive phospholipid. With these complexes we obtained an up to 70-fold increase of transfection with B16-F1 melanoma cells. However when B16-G4F, an alpha-MSH receptor negative melanoma cell line was transfected, an up to 700-fold increased transfection efficiency was observed. The peptide hormone analogue was equally efficient when it was only mixed with lipospermine--DNA complexes without covalent coupling. In addition to melanoma cells we also obtained up to 30-fold increased transfection with BN cells (embryonic liver cells). Our data show that an alpha-MSH analogue increased transfection independently of the MSH receptor expression but reaches efficiencies approaching those obtained with peptides derived from viral fusion proteins. The absence of targeting of constructs containing [Nle(4),D-Phe(7)]-alpha-MSH(4-10) can probably be attributed due to the relatively modest number of MSH receptors at the surface of melanoma. We suggest, however, that the peptide hormone analogue used in this study has membrane-active properties and could be of interest as helper agent to enhance non-viral gene delivery presumably by endosomal-destabilizing properties.

Affinity Labels↗
PubMed2000

Lectin-mediated drug targeting: selection of valency, sugar type (Gal/Lac), and spacer length for cluster glycosides as parameters to distinguish ligand binding to C-type asialoglycoprotein receptors and galectins.

PURPOSE: Common oligosaccharides of cellular glycoconjugates are ligands for more than one type of endogenous lectin. Overlapping specificities to beta-galactosides of C-type lectins and galectins can reduce target selectivity of carbohydrate-ligand-dependent drug targeting. The purpose of this study is to explore distinct features of ligand presentation and structure for design of cluster glycosides to distinguish between asialoglycoprotein-specific (C-type) lectins and galectins. METHODS: Extent of binding of labeled sugar receptors to two types of matrix-immobilized (neo)glycoproteins and to cells was evaluated in the absence and presence of competitive inhibitors. This panel comprised synthetic mono-, bi-, and trivalent glycosides with two spacer lengths and galactose or lactose as ligand part. RESULTS: In contrast to C-type lectins of hepatocytes and macrophages, bi- and trivalent glycosides do not yield a notable glycoside cluster effect for galectins-1 and -3. Also, these Ca2+-independent galactoside-binding proteins prefer to home in on lactose-bearing glycosides relative to galactose as ligand, while spacer length requirements were rather similar. CONCLUSIONS: Trivalent cluster glycosides with Gal/GalNAc as ligand markedly distinguish between C-type lectins and galectins. Undesired side reactivities to galectins for C-type lectin drug delivery will thus be minimal.

Asialoglycoproteins↗
PubMed1999

Design of highly immunogenic liposomal constructs combining structurally independent B cell and T helper cell peptide epitopes.

We have designed liposomal diepitope constructs that allow the physical combination, within the same vesicle, of B and Th epitopes as structurally separate entities. The immune response against such constructs was explored using TPEDPTDPTDPQDPSS (TPE), a B cell epitope originating from a Streptococcus mutans surface adhesin and QYIKANSKFIGITEL (QYI), a "universal" Th epitope from tetanus toxin. The two peptides were linked to the outer surface of small (diameter approximately 100 nm) unilamellar liposomes by covalent conjugation to two different anchors. To that end we have developed a strategy that allows the controlled chemical coupling of TPE and QYI, functionalized at their N terminus with a thiol, to preformed liposomes containing thiol-reactive derivatives of phosphatidylethanolamine and the lipopeptide S-[2,3-bis (palmitoyloxy)-(2-RS)-propyl]-N-palmitoyl-(R)-cysteinyl-alanyl-gly cine (Pam3CAG), respectively. This synthetic construct (administered i.p. to BALB/c mice) induced highly intense (titers > 20,000), anamnestic and long-lasting (over 2 years) immune responses, indicating that this strategy is successful. Two parameters were of prime importance to elicit this response with our liposomal diepitope constructs: (1) the simultaneous expression of B and Th epitopes on the same vesicle, and (2) the lipopeptide Pam3CAG anchor of the Th epitope QYI could not be replaced by a phosphatidylethanolamine anchor (a lesser immune response was observed). Analysis of the antibody response revealed a complex pattern; thus, besides the humoral response (production of IgG1, IgG2a, IgG2b) a superposition of a T-independent (TI-2 type) response was also found (IgM and IgG3). These results indicate that liposomal diepitope constructs could be attractive in the development of synthetic peptide-based vaccines.

Amino Acid Sequence↗
PubMed1999

Clinical significance of bone marrow biopsy and plasma cell morphology in MM and MGUS.

Multiple myeloma (MM) is characterized by plasma cell infiltration in the bone marrow, suppression of normal haematopoiesis, destruction of bone, renal failure and recurrent infections. The extent of organ involvement, severity of complications, drug sensitivity and therefore the clinical course differ widely among patients. Specific and reliable laboratory examinations and especially morphology including both biopsy and aspirations are required to evaluate its aggressivity and extent. In this review of MM and its variants we emphasize the impact of morphology on the diagnostic and prognostic approach to MM and MGUS, and on the planning and monitoring of appropriate therapy.

Biopsy↗
PubMed1998

Design and synthesis of thiol-reactive lipopeptides.

Lipopeptides are potent adjuvants that trigger an immune response against covalently conjugated low molecular mass antigens. We report here the design and synthesis of thiol-reactive lipopeptides (6, 7) which can be incorporated into liposomes and react, under mild conditions, with synthetic peptides carrying a thiol function.

Adjuvants, Immunologic↗
PubMed1997

Temporal and spatial expression patterns of transgenes containing increasing amounts of the Drosophila clock gene period and a lacZ reporter: mapping elements of the PER protein involved in circadian cycling.

Rhythmic oscillations of the PER protein, the product of the Drosophila period (per) gene, in brain neurons of the adult fly are strongly involved in the control of circadian rhythms. We analyzed temporal and spatial expression patterns of three per-reporter fusion genes, which share the same 4 kb regulatory upstream region but contain increasing amounts of per's coding region fused in frame to the bacterial lacZ gene. The fusion proteins contained either the N-terminal half (SG), the N-terminal-two-thirds (BG), or nearly all (XLG) of the PER protein. All constructs led to reporter signals only in the known per-expressing cell types within the anterior CNS and PNS. Whereas the staining intensity of SG files was constantly high at different Zeitgeber times, the in situ signals in BG and XLG files cycled with approximately 24 hr periodicity in the PER-expressing brain cells in wild-type and per01 loss of function files. Despite the rhythmic fusion-gene expression within the relevant neurons of per01 BG files, their locomotor activity in light/dark cycling conditions and in constant darkness was identical to that of per01 controls, uncoupling protein cycling from rhythmic behavior. The XLG construct restored weak behavioral rhythmicity to (otherwise) per01 files, indicating that the C-terminal third of PER (missing in BG) is necessary to fulfill the biological function of this clock protein.

Animals↗
PubMed1997

Synthetic lipopeptides incorporated in liposomes: in vitro stimulation of the proliferation of murine splenocytes and in vivo induction of an immune response against a peptide antigen.

Amphiphilic lipopeptides, such as Pam3CysAlaGly and Pam3CysSerSer, were synthesized and incorporated into liposomes, and their ability to induce the proliferation of BALB/c mouse splenocyte was tested in vitro. When compared to monophosphoryl lipid A (MPL) the following potency order was found: liposomal lipopeptides > liposomal MPL > free (emulsified) lipopeptides. These results strongly depend on the size of the vesicles used: a mitogenic effect was observed only with lipopeptides incorporated within vesicles of diameter < or = 100 nm while lipopeptides in larger vesicles (diameter approximately 300 nm) gave no response. This may be related to the necessity for the liposome-associated lipopeptides to be endocytosed to reach putative intracellular targets. As immunoadjuvanticity seems to be linked to B-lymphocyte activation, the lipopeptides represent attractive alternatives to MPL for the realization of completely synthetic liposome-based peptide vaccine formulations. This was borne out by showing that Pam3CysAlaGly and Pam3CysSerSer, when incorporated in small unilamellar vesicles carrying a covalently conjugated synthetic peptide of sequence IRGERA, corresponding to an epitope of the C-terminal region of histone H3, were able to induce a potent and long-lasting immune response.

Adjuvants, Immunologic↗
PubMed1996

Immunogenicity of new heterobifunctional cross-linking reagents used in the conjugation of synthetic peptides to liposomes.

We have investigated the immunogenicity of six thiol-reactive heterobifunctional cross-linking reagents that permit the conjugation of cysteine carrying peptides to the surface of liposome containing monophosphoryl lipid A. Such constructs elicit an immune response against short synthetic peptides and our aim was to find the least immunogenic linkers to limit potential carrier-induced epitopic suppression. For that purpose the properties of three new polyoxyethylene linkers of different lengths and thiol-reactive moieties (maleimide, bromoacetyl, dithiopyridine) were compared to known derivatives obtained by reacting the classical reagents SMPB and SPDP or N-succinimidyl bromoacetate with phosphatidylethanolamine. The least immunogenic linkers were the bromoacetate derivatives whereas those containing a maleimide group evoked a significant anti-linker immune response. In addition, using IRGERA as a model peptide, we found that all six liposomal constructs strongly elicited the production of anti-peptide IgG antibodies. This immune response was therefore independent of the length of the linkers (ranging between 0.3 and 1.6 nm) and of the nature of the linkage. between the peptide and the thiol-reactive moieties of the cross-linkers, i.e. stable thioether or bio-reducible disulfide bonds.

Amino Acid Sequence↗
PubMed1996

Staining in the brain of Pachymorpha sexguttata mediated by an antibody against a Drosophila clock-gene product: labeling of cells with possible importance for the beetle's circadian rhythms.

Central nervous system ganglia within the head of the beetle Pachymorpha sexguttata were labeled using an antibody that recognizes an evolutionarily conserved region of the period (per) gene product of Drosophila melanogaster. per and the protein it encodes (PER) are believed to play a central role in the generation of endogenous circadian rhythms in flies; therefore anti-PER-mediated immunoreactivity may help to uncover cellular components of the circadian clock system in that insect and in others. In the beetle, application of this antibody led to the staining of a distinct set of neurons located in the optic lobes and the central brain, plus small numbers of putative glial cells in the optic lobes. Neuronal perikarya (including their nuclei in a few cases), the axons, and terminal regions of the neurons were stained. The network formed by these labeled cells and processes are candidates for the neuronal basis of the beetle's circadian clock system: the pacemaker region situated next to the medulla neuropil, its connection to the apparent site of Zeitgeber input, and putative efferent pathways projecting to control centers of various effector systems. Anti-PER-mediated labeling and that resulting from application to beetle specimens of an antiserum against pigment-dispersing hormone (PDH) were compared; in the Drosophila brain all "PDH cells" express the per gene as well. In the beetle, however, the set of "PER cells" and PDH ones is at least in part nonoverlapping. The hypothesis that neurons stained by application of anti-PER participate in the control of the beetle's circadian rhythms is discussed in the context of previous electrophysiological and immunohistochemical studies. Also considered are analogies to, and differences from, labeling of the PER protein in fruit flies and PER-like immunoreactivity in other animals.

Animals↗
PubMed1995

Efficient gene delivery with neutral complexes of lipospermine and thiol-reactive phospholipids.

The presence of thiol-reactive phospholipid derivatives, such as N-4-(p-maleimidophenyl)butyryl) dipalmitoylphosphatidylethanolamine (MPB-DPPE), in electrically neutral lipospermine/DNA particles results in more than a 100-fold increased transfection efficiency of human hepatoma HepG2 cells and murine 3T3 fibroblasts. These effects could be ascribed to the presence of thiol-reactive functions, such as maleimide, bromoacetamide and dithiopyridyl linkage, on the transfecting particles. We propose that such particles react with thiol groups present at the surface of the cells, leading to their covalent anchoring, a process that is probably followed by an endocytosis of the complex.

3T3 Cells↗
PubMed1994

Selective induction of protection against influenza virus infection in mice by a lipid-peptide conjugate delivered in liposomes.

We have previously reported (Muller et al. Vaccine 1990, 8, 308) that two cyclic peptide analogues called D loop and K loop, corresponding to residues 139-147 in site A of the haemagglutinin (HA) of influenza A virus (strain X31), were both able to provide protective immunity to infected OF1 mice when administered in the form of peptide-ovalbumin conjugates. The predicted conformation of the D loop is nearly identical to that of the native loop known from the X-ray structure of HA, while the predicted conformation of the K loop differs significantly from the native one. In this study, the two peptides were conjugated to small unilamellar liposomes, thus creating a chemically defined immunogen, and OF1 mice were immunized with these liposomes containing monophosphoryl lipid A as adjuvant. Compared with protein carrier systems, the liposomal preparations are completely synthetic and avoid the use of Freund's adjuvant. By using liposomes associated with the D loop, we were able to achieve 70% protection of the mice against intranasal challenge with the influenza virus while no protection was obtained with the liposome-associated K loop. The difference in effect between the two liposome and ovalbumin carrier systems may result from the induction of different structures in the peptides when coupled to lipid anchors than when coupled to proteins.

Administration, Intranasal↗
PubMed1994

A promoterless period gene mediates behavioral rhythmicity and cyclical per expression in a restricted subset of the Drosophila nervous system.

Transgenic flies carrying a 7.2 kb piece of DNA from the period (per) gene were analyzed for the presence of circadian locomotor activity rhythms and fluctuations of per-encoded mRNA and protein. The 5' end of this genomic fragment is within the first intron, which precedes the coding region. This promotorless fragment could rescue circadian behavioral rhythms and mediate spatial expression of PER in a subset of wild-type per cells within the CNS and PNS. In one behaviorally rhythmic line, PER protein was found in only "per lateral neurons." In the rhythmic transgenics, per mRNA and protein levels undergo circadian cycling, as previously described for wild type. Cycling of PER in brain cells of flies carrying the same 7.2 kb piece of per DNA under the control of a heat shock promoter corroborated the hypothesis that per's molecular cyclings and behavioral rhythmicity are causally related.

Animals↗
PubMed1994

Bone formation in coralline hydroxyapatite. Effects of pore size studied in rabbits.

We analyzed osseous reactions in the rabbit femoral condyle to coralline hydroxyapatite bone substitutes of various pore sizes by radiology and histology. The results were compared to bone repair of empty cavities and to integration of allografts. Spontaneous bone repair of the empty cavities took approximately 12 weeks, while integration of the cryopreserved allografts occurred after 9 weeks. However, no signs of new bone formation were found with the 200 microns pore size hydroxyapatite. In contrast, there was substantial production of bone within the 500 microns pore size implants at 12 and 26 weeks. Our results indicate that the pore size of the coralline hydroxyapatite influenced the development of bone in the implants in the cancellous bone bed of the rabbit femoral condyle. The results also show that spontaneous bone repair should be taken into consideration when the integration of implants is evaluated.

Animals↗
PubMed1993

A new type of putative non-visual photoreceptors in the optic lobe of beetles.

A putative photoreceptor organ is described in the carabid beetle, Pachymorpha sexguttata. The elongated structure, about 20-40 microns wide and more than 300 microns long, is situated within the optic lobe at the fronto-dorsal rim of the lamina. It lies, deep in the head capsule, in front of the compound eyes and beneath window-like thinnings of the cuticle. The organ is composed of two types of cells: (1) clear sheath cells and (2) well-organized inner receptor cells that appear in a horseshoe-like or circular array in cross-section. Common histological features of all inner cells include a distal trunk ending in microvilli that form a rhabdom-like structure, an axon at the proximal end of the cell, lamellar and multivesicular bodies within the trunk, and clusters of small mitochondria. The organ has no shielding pigment. It is connected by thin axons to a circumscribed neuropil that parallels the organ, and thence via a fiber tract to the medulla accessoria, a possible site of the circadian pacemaker in insects. Immunoreactivity to anti-per(s), an antibody recognizing the Drosophila period (per) protein that plays a central role in the function of the circadian pacemaker in fruit flies, is demonstratable in thin efferent terminals within the organ, in the associated neuropil and in its fiber connection to the medulla. A second receptor organ displaying the same fine structure lies near the second optic chiasm. This set of putative photoreceptors also occurs in the tenebrionid beetle, Zophobas morio, and its pupa. The possible function of these receptor organs is discussed with respect to former chronobiological data and some recently described types of extraretinal photoreceptors in arthropods.

Animals↗
PubMed1993

Potential of bone marrow biopsy in chronic myeloproliferative disorders (MPD).

The chronic myeloproliferative disorders (MPD) comprise polycythemia vera (PV), idiopathic thrombocythemia (IT), chronic myeloid leukemia (CML) and myelofibrosis/osteomyelosclerosis (MF/OMS). Bone marrow biopsies of 3500 patients with known or suspected MPD were studied, and the clinical and morphologic variables registered were utilized for multivariate data analysis by selected BMD computer programs. The histologic criteria and the histologic subdivisions, as well as the evolution and prognosis of disease are outlined for each of the clinical entities. The results show that a bone marrow biopsy provides independent diagnostic and prognostic data in this group of hematologic malignancies and therefore constitutes an additional parameter in the diagnostic investigation of patients with suspected or established MPD.

Biopsy↗
PubMed1992

Morphologic classification of the myelodysplastic syndromes (MDS): combined utilization of bone marrow aspirates and trephine biopsies.

In a retrospective and prospective follow-up study from 1975 to 1991, bone marrow biopsies, aspirates and clinical features of 495 patients with MDS were investigated. Sections of undecalcified plastic embedded biopsies and smears of bone marrow aspirates were stained according to Giemsa. Bone marrows with MDS were characterized by three main categories of morphologic alterations: (1) cellular abnormalities, (2) architectural disorganization in the bone marrow and (3) stromal changes; the combined use of aspirates and trephine biopsies enabled a more reliable and accurate diagnosis of MDS than either one alone. The bone marrow findings fell into one of 7 subtypes, with the frequencies and median survivals in brackets: (1) MDS sideroblastic (19%, 62 months), (2) MDS megaloblastoid (13%, 56 months), (3) MDS proliferative (22%, 31 months), (4) MDS blastic (15%, 9 months), (5) MDS hypoplastic (15%, 26 months), (6) MDS fibrotic (6%, 29 months), and (7) MDS inflammatory (10%, 42 months). In follow-up studies patients with secondary MDS were excluded and the prognosis and subsequent evolution for each of the morphologic subtypes were evaluated. The conclusion is drawn that aspirates and trephine biopsies are complementary procedures and both are required for diagnosis, classification and decisions on current treatment modalities of patients with MDS.

Adolescent↗
PubMed1992

Expression of the period clock gene within different cell types in the brain of Drosophila adults and mosaic analysis of these cells' influence on circadian behavioral rhythms.

The product of the period (per) gene of Drosophila melanogaster is continuously required for the functioning of the circadian pacemaker of locomotor activity. We have used internally marked mosaics to determine the anatomical locations at which per expression is required for adult rhythmicity, and thus where the fly's circadian pacemaker is likely located in this holometabolous insect. We first provide a detailed description of the distribution and nature of per-expressing cells in the fly's CNS. Using an antibody to the per gene product, or to that of a reporter of per expression, in conjunction with an antibody to the embryonic lethal-abnormal visual system (elav) gene product--which is used as a marker of neuronal identity--we have experimentally confirmed previously proposed assignments of per-expressing cells to the neuronal and glial classes. Thus, we found that per expression and elav immunoreactivity colocalized in large cells located in the lateral cortex of the central brain, as well as in more dorsally located cells in the posterior central brain. In contrast, we found that cells located at the margins of the cortex and the neuropil, and within the neuropil, as well as smaller cortical cells found throughout the brain's cortex, were elav negative, supporting the notion that they are glial in nature. Using internally marked mosaics, we find that the pacemaker is located in brain but is not exclusive to the eyes, the ocelli, or the optic lobes, which is consistent with previous reports obtained in this and other insects of this class. Although the pacemaker may be a paired structure, we show that the functioning of one of them is sufficient for rhythmicity. Finally, we report that glial expression is sufficient for some behavioral rhythmicity to be manifest. However, the rhythmicities of animals for which per expression was confined to glia were weak, suggesting that neuronal per expression as well may be required for normal pacemaker function.

Animals↗