1H magnetic resonance imaging and 31P magnetic resonance spectroscopy in experimental filariasis

1H Magnetic resonance imaging and 31P magnetic resonance spectroscopy (MRS) have been carried out in experimental rodent filariasis, i.e., Acanthocheilonema viteae infection in the rodent host, Mastomys coucha. The T2-weighted image of the infected host shows fine hyperintense thread like structures of adult filariid nests in the cervical region. 31P MRS of normal and infected hosts, localized over the same region of interest, show seven major peaks corresponding to phosphomonoesters (including glucose-6-phosphate, fructose-6-phosphate, fructose-1-6-diphosphate, phosphorylcholine, and adenine monophosphate or AMP), inorganic phosphate, glycerophosphorylcholine, phosphoenolpyruvate, phosphocreatine and nucleoside di- and tri-phosphates. Concentrations of phosphomonoesters (PMEs) are higher in the normal rodent compared with the infected ones. In vivo 31P MRS provides a non-invasive assessment of tissue bioenergetics and phospholipid metabolism.

Role of in vivo proton magnetic resonance spectroscopy in the diagnosis and management of brain abscesses

OBJECTIVE

In vivo proton magnetic resonance spectroscopy was performed for 24 patients with pyogenic brain abscesses, to examine the consistency of the spectral patterns and to observe the changes in metabolites with treatment.

METHODS

Localized proton spectra were obtained from 4- to 8-ml volumes in the abscesses, using stimulated echo acquisition mode and spin echo sequences. Twenty-two patients were treated with combined surgical and medical therapy, and two patients were treated conservatively. High-resolution magnetic resonance spectroscopy was performed for 15 samples of abscesses obtained from these patients, to confirm the assignments of resonances seen in vivo. Postaspiration studies were performed for 12 patients treated with combined medical and surgical therapy and 2 patients treated medically.

RESULTS

Lactate and amino acids were seen in spectra for all patients, irrespective of the time of spectroscopy after the onset of combined medical and surgical therapy. Acetate and pyruvate disappeared after 1 week of combined treatment.

CONCLUSION

It was concluded that spectral patterns for brain abscesses are consistent and specific and can assist in the noninvasive diagnosis of abscesses. Responses to combined treatment could be monitored by showing the changes in metabolite patterns in serial spectroscopic studies.

Seasonal dynamics of the tissue levels of total protein, free amino acid and ribonucleic acid in an Indian air-breathing teleost, Channa punctatus

The tropical freshwater air-breathing teleost, Channa punctatus, reveals a seasonal metabolic reorganization with reference to its biochemical tissue compositions. The summer-adapted and winter-adapted C. punctatus seem to be two biochemically distinct populations. Besides, the different reproductive phases viz. prespawning, spawning, post-spawning, preparatory-I and preparatory-II are also biochemically distinct.

Chemoenzymatic synthesis of dendritic sialyl Lewis(x)

Traditional structure activity relationship studies (SAR) have led to the development of numerous sialyl Lewis(x) analogs in the search for potential antiinflammatory agents. However, these methods do not take into account cluster or multivalent effects. Reported herein is the chemoenzymatic synthesis of di-, tetra-, and octa-valent sLe(x) ligands scaffolded on dendrimers. Hypervalent L-lysine cores with covalently attached 2-acetamido-2-deoxy-D-glucose (N-acetylglucosamine, GlcNAc) residues were chemically prepared and enzymatically transformed into sLe(x) containing dendrimers so that multivalency, and its role in selectin-sLe(x) interactions may be evaluated. This work constitutes another successful enzymatic synthesis of sLe(x) and represents the first example of GlcNAc elongation on a synthetic dendrimer scaffold. These sLe(x) dendrimers are currently being investigated as selectin antagonists.

Infrared fluorescent detection of D1S80 alleles from blood and body fluid collected on IsoCode devices

A genetic locus D1S80 (pMCT 118) containing variable number of tandem repeats (VNTR) has been used extensively in forensic analysis and paternity testing. In the current research, DNA was isolated from blood saliva and nasal secretions collected on two types of IsoCode paper-based devices. The D1S80 locus was amplified using PCR technology, and the alleles were separated by gel electrophoresis and then detected using an infrared (IR) fluorescence automated DNA sequencer. IR-labeled amplification products were generated from human genomic DNA using oligonucleotide primers, which were covalently linked to an infrared fluorescent dye (IRD41) at the 5' end. This system combines IR fluorescence chemistry and laser technology, thus eliminating the need for post-electrophoretic gel handling for the detection of the alleles. Real-time detection after separation of the alleles is valuable for visualization of the data. The VNTR alleles are displayed as familiar autoradiogram-like images, which can also be analyzed by computer. Since DNA is eluted from the IsoCode devices only with sterile distilled water and without time-consuming methods of extraction, amplification can be performed from numerous samples within a short period of time.

Dexamethasone - Cyclophosphamide pulse (DCP) therapy in Pemphigus

Of the 37 patients enrolled for this treatment, 13 have been lost to follow up and 4 have died. Of the remaining 20, 8 are already in remission (40%), while 12 are still having active disease. Of the 8 patients who are now in remission, 1 is in phase II and taking monthly dexamethasone cyclophosphamide pulse and 50 mg cyclophosphamide daily while in 3 patients all the treatment has already been withdrawn (phase IV). All these patients are being followed up for any recurrence. The duration of remission has been more than 6 months in 7 patients (maximum 2 years). The chief side-effect observed was increased susceptibility to pyogenic and candidal infections of the skin and oral mucosa respectively. The other side-effects noted were generalized weakness and lethargy following DCP (1), irregular menstrual periods (1), amenorrhoea (1), general darkening of complexion (1), steroid psychosis (1), transient eosinophilia (1) and marked transient oligospermia.

Acrokerato - elastoidosis of costa: Report of three cases

Three cases of acrokeratoelastoidosis of Costa are reported. All the patients were females with marginal keratodermas composed of cornified papules, some of which were umbilicated, distributed along the borders of the hands and feet. A positive family history was present in all the cases.

Synthesis and biological properties of mannosylated starburst poly(amidoamine) dendrimers

Starburst PAMAM dendrimers ending with mannopyranoside residues were readily synthesized in large scale and good yields from commercially available dendrimers bearing high-density amine functionality on their surface and p-isothiocyanatophenyl 2,3,4,6-tetra-O-acetyl-alpha-D-mannopyranoside. The first four generations of this novel class of monodispersed neoglycoconjugates having up to 32 mannoside units were evaluated as ligands for the phytohemagglutinins from concanavalin A (Con A) and Pisum sativum (pea lectin) using enzyme-linked lectin assay (ELLA) and turbidimetric analyses. The binding properties of these glycodendrimers, together with reference monosaccharides, were determined using yeast mannan as a coating antigen and peroxidase-labeled lectins. These mannosylated dendrimers were demonstrated to be potent inhibitors with IC50 values 400 times better than those of monomeric methyl alpha-D-mannopyranoside taken as a standard. Their lipophilic character was shown to be sufficient for their direct use as coating antigens in microtiter plate assays. Moreover, their ability to bind and form insoluble carbohydrate-lectin complexes was also demonstrated by radial double immunodiffusion and turbidimetric analyses. Furthermore, the ability of these ligands to selectively precipitate a mannose-binding protein (Con A) from a crude lectin mixture was also demonstrated using polyacrylamide gel electrophoresis (SDS-PAGE). These multivalent neoglycoconjugates were shown to constitute novel biochromatography materials of high affinity for the easy isolation of carbohydrate-binding proteins.

Prevention by anti-LFA-1 of acute myoblast death following transplantation

Myoblast transplantation is a potential treatment for Duchenne muscular dystrophy. One of the problems possibly responsible for the limited success of clinical trials is the rapid death of the myoblasts after transplantation. To investigate this problem, myoblasts expressing beta-galactosidase were injected in the tibialis anterior muscles of mice. Beta-galactosidase activity was reduced by 74.7% after 3 days. Myoblast death observed at 3 days was reduced to 57.2% when the hosts were irradiated. This result suggested that host cells were contributing to this phenomenon. Transplantation in SCID and FK506-treated mice did not reduce cell death, indicating that mortality was not due to an acute specific reaction. In contrast, administration of the anti-LFA-1 (TIB-213) mAb markedly reduced myoblast death at 3 days without altering leukocyte tissue infiltration. We postulated that neutrophils were mediating myoblast mortality by an LFA-1-dependent mechanism. To test this hypothesis, IL-1beta-activated myoblasts were loaded with 6-carboxy-2',7'-dichlorodihydrofluorescein diacetate, di(acetoxymethylester) (DCFH), a marker for oxidative stress. Addition of neutrophils and zymosan-activated serum resulted in a time-dependent DCFH fluorescence; this neutrophil-induced oxidation was considerably inhibited by TIB-213. These results indicate that an effective control of the inflammatory reaction will be necessary for any new clinical trials of myoblast transplantation and suggest that neutrophil-mediated myoblast injury occurs by an LFA-1-dependent pathway.

MR imaging, MR angiography, and MR spectroscopy of the brain in eclampsia

PURPOSE

To compare the MR imaging and MR angiographic changes with in vivo proton MR spectroscopic findings and to determine the spectral differences between edema and ischemia in patients with eclampsia.

METHODS

Spin-echo MR imaging, MR angiography, and single-voxel proton MR spectroscopy were performed in 10 patients with eclampsia. MR studies were obtained within 3 to 5 days of diagnosis and repeated after 2 weeks with identical parameters.

RESULTS

Multifocal subcortical/cortical hyperintensities were noted in all 10 patients on T2-weighted images; in two patients, hyperintensities were seen in both cerebral hemispheres. In nine patients, MR angiograms showed narrowing of the major vessels constituting the circle of Willis that resolved after 2 weeks. In one patient with subtle imaging changes, MR angiography showed mild bilateral narrowing of the proximal middle and posterior cerebral arteries that did not change after 2 weeks, whereas imaging abnormalities worsened. Findings at single-voxel MR spectroscopy of the reversible T2 hyperintense lesions were significantly different from findings in the control group for N-acetylaspartate (NAA)/creatine ratios. One patient with mild abnormalities at MR imaging and MR angiography had lactate and decreased creatine and NAA, and on a follow-up study had a further decrease of NAA and creatine as well as a decrease in lactate.

CONCLUSION

In vivo proton MR spectroscopy may help to differentiate cerebral edema from ischemia in patients with eclampsia and thus may help to determine the prognosis for these patients.

Prevention by anti-LFA-1 of acute myoblast death following transplantation

Myoblast transplantation is a potential treatment for Duchenne muscular dystrophy. One of the problems possibly responsible for the limited success of clinical trials is the rapid death of the myoblasts after transplantation. To investigate this problem, myoblasts expressing beta-galactosidase were injected in the tibialis anterior muscles of mice. Beta-galactosidase activity was reduced by 74.7% after 3 days. Myoblast death observed at 3 days was reduced to 57.2% when the hosts were irradiated. This result suggested that host cells were contributing to this phenomenon. Transplantation in SCID and FK506-treated mice did not reduce cell death, indicating that mortality was not due to an acute specific reaction. In contrast, administration of the anti-LFA-1 (TIB-213) mAb markedly reduced myoblast death at 3 days without altering leukocyte tissue infiltration. We postulated that neutrophils were mediating myoblast mortality by an LFA-1-dependent mechanism. To test this hypothesis, IL-1beta-activated myoblasts were loaded with 6-carboxy-2',7'-dichlorodihydrofluorescein diacetate, di(acetoxymethylester) (DCFH), a marker for oxidative stress. Addition of neutrophils and zymosan-activated serum resulted in a time-dependent DCFH fluorescence; this neutrophil-induced oxidation was considerably inhibited by TIB-213. These results indicate that an effective control of the inflammatory reaction will be necessary for any new clinical trials of myoblast transplantation and suggest that neutrophil-mediated myoblast injury occurs by an LFA-1-dependent pathway.

Infrared fluorescent detection of D1S80 alleles

A genetic locus D1S80 containing a variable number of tandem repeats (VNTR) has been used extensively in forensic analysis and paternity testing. In the current research, the D1S80 locus was amplified using polymerase chain reaction (PCR) technology and the alleles detected using a high sensitivity infrared (IR) fluorescence automated DNA sequencer. IR-labeled amplification products were generated using oligonucleotide primers which were covalently linked to an infrared fluorescent dye (IRD41) at the 5'-end. Human genomic DNA (1.0 ng or less) isolated from blood and various simulated forensic samples was successfully amplified using this technology. Allelic bands were detected by incorporation of the IR fluorescent dye into PCR products. Both Long Ranger and polyacrylamide denaturing gels permitted clear resolution of individual alleles that differ by only one repeat unit. In the smaller gels a separation distance of only 15 cm allowed separation of the alleles in less than 2 h from sample loading to visualization. This system combines IR fluorescence chemistry and laser technology thus eliminating the need for post-electrophoretic gel handling for the detection of D1S80 alleles. Real-time detection is valuable for immediate visualization of the data and the alleles are displayed as familiar autoradiogram-like images which can also be analyzed by computer. By loading a 64-lane gel twice it is possible to type at least 120 samples in 1 day using a single gel.

Specific recognition of O6-methylguanine in DNA by active site mutants of human O6-methylguanine-DNA methyltransferase

O6-Methylguanine-DNA methyltransferase (MGMT), a ubiquitous DNA repair protein, acts as a monomer in removing the mutagenic DNA adduct O6-alkylguanine (induced by alkylating carcinogens) via a stoichiometric reaction. The alkyl group is transferred without a cofactor to a specific cysteine acceptor residue of MGMT, Cys-145 in the case of human MGMT, containing 207 amino acid residues and thereby inactivates the protein. As a prelude to the investigation of the reaction mechanism of human MGMT by elucidation of its structure in free and substrate-bound forms via NMR spectroscopy and X-ray crystallography, two types of MGMT mutants were generated and characterized. First, systematic deletion analysis of the protein was carried out to determine the smallest size at which it is active or inactive but forms a stable complex with the substrate and so may be useful for NMR spetroscopic analysis. Deletion of more than 8 or 31 residues from the amino or carboxyl terminus, respectively, led to the loss of both activity and substrate binding. Removal of Arg-9 or Leu-176 and distal residues inactivated the protein, presumably by altering its tertiary structure. On the basis of the criteria of bacterial overexpression and solubility, the mutant MGMT with deletion of 28 residues at the carboxyl terminus should be suitable for NMR studies. In the second approach, we examined mutants at the active site (Cys-145) that retain substrate binding. Inactive C145A and C145S substitution mutants were found to form specific and stable complexes with an O6-methylguanine (m6G)-containing oligonucleotide substrate. Wild type MGMT also formed a similar complex, but only as a transient intermediate. Footprinting studies indicated a strong discriminatory effect of the base adduct on the binding of C145A to substrate DNA; 17-18 nucleotides on the m6G-containing strand and 13-14 nucleotides in the complementary strand spanning the base adduct were protected from DNase I digestion by the mutant protein. These results, as well as the identical protease sensitivity of the wild type and mutant proteins, suggest minimal structural change due to conservative mutations at the active site. Thus, the mutant proteins may be utilized for solving the structure and mechanism of human MGMT.

Infrared fluorescent detection of PCR amplified gender identifying alleles

An automated DNA sequencer utilizing high sensitivity infrared (IR) fluorescence technology together with Polymerase Chain Reaction (PCR) methodology was used to detect several sex differentiating loci on the X and Y chromosomes from various samples often encountered in forensic case work. Amplifications of the X-Y homologous amelogenin gene, the alpha-satellite (alphoid) repeat sequences and the X and Y chromosome zinc finger protein genes ZFX and ZFY (ZFX/ZFY) were performed. DNA extracted from various forensic specimens was amplified using either Taq, Tth or ThermoSequenase. Multiplexing using primers for all three loci in one reaction tube was achieved using Tth and ThermoSequenase. Two IR labeling strategies for detection of PCR products were utilized. In the first strategy, one of the PCR primers contained a 19-base extension at its 5' end identical to an IR-labeled universal M13 Forward (-29) primer which was included in the amplification reactions. During PCR the tailed primer generates sequence complementary to the M13 primer which subsequently primes the initial amplification products, thereby generating IR-labeled PCR products. In the second strategy, dATP labeled with an IR dye (IR-dATP) was included in the amplification reaction. During amplification IR-dATP was utilized by the polymerase and incorporated into the synthesized DNA, thus resulting in IR-labeled PCR products. X and Y specific bands were readily detected using both labeling methodologies. Amplified products were electrophoretically resolved using denaturing Long-Ranger gels and detected with an automated detection system using IR laser irradiation. A separation distance of 15 cm allowed run times of less than 2 h from sample loading to detection. Because the gels could be run more than once, at least 120 samples (2 loads x 60 samples/load) can be typed using a single gel.

Optimizing lectin-carbohydrate interactions: improved binding of divalent alpha-mannosylated ligands towards Concanavalin A

The synthesis and binding properties to Jack bean phytohaemagglutinin in (Concanavalin A, Con A) of a new family of divalent alpha-D-mannopyranoside ligands are described. The synthesis of these ligands is based on the coupling of commercially available diamines to p-isothiocyanatophenyl 2,3,4,6 tetra-O-acetyl-alpha-D-mannopyranoside (4). The resulting dimers 6, 15 to 22 and 30 were tested for their relative inhibitory potency by solid-phase enzyme-linked lectin assays (ELLA) using methyl alpha-D-mannopyranoside as standard. Divalent mannosylated ligand 35 bearing a non-aromatic aglycon was also tested for comparison purposes. Concentrations necessary for 50% inhibition (IC50s) of binding of yeast mannan to Jack bean phytohaemagglutinin (Con A) were determined. The inhibitions showed dimers to be approximately 10- to 90-fold more potent than methyl alpha-D-mannopyranoside. Variations in the intra-mannosyl distance proved to be an important factor for optimum binding.

Role of non-major histocompatibility complex antigens in the rejection of transplanted myoblasts

Myoblasts obtained from donors histoincompatible for several non-major histocompatibility complex antigens (i.e., including minor histocompatibility antigens) and from syngeneic donors were transplanted without any immunosuppression into the muscles of male dystrophic C57BL/10J mdx/mdx mice. Myoblasts from syngeneic mice resulted in the formation of a high percentage of dystrophin-positive fibers 16 weeks after the transplantation. There was no evidence of a cellular immune reaction against the donor myoblasts, i.e., no infiltration by CD4 or CD8 lymphocytes and no increased expression of granzyme B and interferon-gamma mRNAs. Transplantation of myoblasts obtained from donors histoincompatible only for non- major histocompatibility complex antigens produced a transient increase of dystrophin-positive fibers at 4 weeks after transplantation for some donor strains but not for others. For donor strains that did produce an increase at 4 weeks, the number of dystrophin-positive fibers was reduced 16 weeks after the transplantation. There was evidence of a cellular immune reaction-infiltration by CD4 and by CD8 lymphocytes and increased expression of granzyme B and interferon-gamma mRNAs. Transplantation of myoblasts obtained from male C57BL/10J +/+ mice into female C57BL/10J mdx/mdx mice also led to the presence of only a few dystrophin-positive fibers with the same signs of cellular immune reaction. In this later case, the cellular immune response was attributed to the H-Y minor antigens. Finally, antibodies against fetal calf serum were detected after both syngeneic and nonsyngeneic transplantations, indicating that the culture medium may also be a source of antigens. In mice, the presence of these antibodies against culture medium did not reduce the success of a first syngeneic transplantation.

Multiplex amplification of STR loci with gender alleles using infrared fluorescence detection

The analysis of short tandem repeat (STR) polymorphisms has proven extremely useful for gene mapping, paternity testing, and forensic analysis. Several commercial products are currently available for performing amplification and analysis of STRs. We have adapted Promega Geneprint Systems for use with a high sensitivity infrared (IR) fluorescent automated DNA sequencer. IR-labeled amplification products are generated by including a small quantity of IR-labeled dATP in the reaction. Several Geneprint STR loci can be multiplexed together with the amelogenin sex identification locus in a single amplification reaction. We have successfully amplified up to five Geneprint STR loci together with the amelogenin locus thus improving the throughput of analysis. Purified genomic DNA as well as simulated forensic samples have been utilized for these multiplex amplifications.