Phase I study of direct gene transfer of an allogeneic histocompatibility antigen, HLA-B7, in patients with metastatic melanoma

PURPOSE

To determine the safety, toxicity, and efficacy of direct intratumoral injection of an allogeneic major histocompatibility complex (MHC) class I gene, HLA-B7, in a cationic lipid vector (Allovectin-7; Vical Inc, San Diego, CA) in patients with metastatic melanoma.

PATIENTS AND METHODS

Seventeen HLA-B7-negative patients were treated with intralesional injection of Allovectin-7. Twelve patients received a single intralesional injection containing 10 micrograms (four patients), 50 micrograms (five patients), or 250 micrograms (three patients) of plasmid DNA. Five patients received two or three injections of 10 micrograms DNA to a single tumor site at 2-week intervals. Tumor biopsies pretherapy and 2 and 4 weeks after gene injection were obtained to determine expression of the plasmid by polymerase chain reaction (PCR), reverse transcriptase (RT)-PCR, flow cytometry, and immunohistochemistry.

RESULTS

Toxicities were related to technical aspects of the injections or biopsies. These included pain, hemorrhage, pneumothorax, and hypotension. Two patients were hospitalized overnight for observation. Seven patients (50%) had tumor responses insofar as the injected nodule decreased > or = 25% by radiologic or physical examination. One patient with a single site of disease achieved a complete remission. Ninety-three percent of the patients' post-gene therapy biopsies contained HLA-B7 plasmid DNA, mRNA, or protein.

CONCLUSION

Intratumoral injection of the allogeneic histocompatibility gene, HLA-B7, in a lipid vector can be performed safely at plasmid DNA doses < or = 250 micrograms. The safety profile and biologic activity of this therapy warrants further studies to define the mechanism of action, predictors of response, and antitumor efficacy of this approach.

Tubulin assembly in the presence of calcium ions and taxol: microtubule bundling and formation of macrotubule-ring complexes

It has been confirmed that taxol is able to prevent Ca(2+)-induced inhibition of microtubule formation from tubulin in the presence of microtubule-associated proteins. However, by means of electron microscopy and scanning force microscopy it could be demonstrated that assembly in the presence of Ca2+ and taxol leads to structural aberrations. The kind of aberration depends on the order of addition of taxol and Ca2+ to tubulin. When taxol was added first, microtubules were formed preferentially. But, these microtubules typically associated with each other by close wall-to-wall alignments or they formed complexes with some C-shaped protofilament ribbons, resulting in microtubule bundles or doublet- and triplet-like microtubule structures, respectively. When Ca2+ was added first, macrotubules, rings, and ring crystals were the dominant assembly products. Mostly, the macrotubules were also bundled or they enclosed rings in their lumen. The findings clearly demonstrate the potency of Ca2+ to induce different polymorphic assemblies with additional protofilament associations, not realized in microtubules.

Localization of G-proteins in macrophages and E. coli during phagocytosis

Heterotrimeric GTP-binding proteins (G-proteins) have been shown to play an important role in cellular signalling. However, G-protein involvement in the intracellular spreading of bacterial pathogens is still poorly understood. In this study, antibodies, that recognize G-protein alpha-subunits (anti-G alpha), were used to investigate the localization of G-proteins in the macrophage-like cell line P388D1 and E. coli, also in their L-forms, during phagocytosis. In E. coli, anti-G alpha-binding sites were detected preferably in the cell wall and septa of the whole bacterial forms as well as in the cytoplasm of L-forms. Western blotting of bacterial lysates demonstrated protein bands with positive immunoreaction to antibodies against Gs alpha, Gi alpha, and Gcommon alpha with a higher affinity to the antibody against Gs alpha. Immunoreaction with the anti-Gs alpha-antibody was markedly higher in pathogenic strains of E. coli. Because of the conserved structure in all GTP-binding proteins which seem to derive from a single primordial protein involved in signal transduction mechanisms, it is reasonable to assume that some anti-Ga-positive proteins in E. coli might be related to G-proteins of higher organisms. A putative candidate for bacterial G-proteins seems to be a 36 kDa protein. Enhancement in G-protein immunostaining in the cytoplasm of macrophages around the internalized bacteria testifies to the involvement of G-proteins in mediation of endocytosis responses of phagocytes.

[Pruritometer 1: Portable measuring system for quantifying scratching as an objective measure of cholestatic pruritus]

Objective assessment of subjective symptoms such as pruritus always presents problems, which can often be resolved only indirectly. The objectification of pruritus was necessitated by a study on the efficacy of a serotonin antagonist used as treatment of cholestatic pruritus. In the present paper, a portable measuring system for the indirect objective assessment of pruritus via the quantification of scratching is described. A piezoelectric scratch-vibration sensor for attachment to the middle finger of the patient's dominant hand was developed. A sensor interface detects the scratching signals and generates pulses that are then summed in an adapted sports watch. The entire system-Pruritometer 1- is worn by the patient like a wrist watch, and is characterized by ease of handling. Acceptance by the patient is reported to be good. A statistically good correlation between measured (Pruritometer) and visually counted scratches was demonstrated. Pruritometer 2, which will enable scratch frequency and intensity distribution over time to be determined, is presently being developed.

Deletion of a B800-850 light-harvesting complex in Rhodospirillum molischianum DSM119 leads to "revertants" expressing a B800-820 complex: insights into pigment binding

A B800-850 light-harvesting complex (also called LH2) deficient strain of Rhodospirillum molischianum was constructed by replacing a portion of the LH2 gene cluster by a kanamycin resistance gene cartridge. The LH2 deficient strain was characterized spectroscopically and by Southern blot analysis. Surprisingly, pseudorevertants were obtained which express a B800-820 complex which could not be observed in the wild type. This B800-820 complex was isolated and characterized. It consists of an alpha- and a beta subunit with 56 and 45 amino acid residues, respectively. The amino acid sequences of both subunits are extremely similar to those of the corresponding B800-850 complex. Resonance Raman spectroscopy shows that in the B800-820 complex the two 2-acetylcarbonyl groups of the bacteriochlo-rophyll a (BChl a) molecules absorbing at 820 nm are free from hydrogen bond interactions, whereas one of the two 2-acetylcarbonyl groups of the pair of BChl a molecules absorbing at 850 nm of the B800- 850 complex is involved in hydrogen bonds. These different protein- pigment interactions are due to the replacement of alpha Trp43 in the B800-850 complex by a Phe in the B800- 820 complex. Comparison of the amino acid sequences of the B800-850 and B800-820 complexes of Rs. molischianum and Rhodopseudomonas acidophila reveals a conserved motif comprised of three amino acid residues. Molecular modeling using the known LH2 structure of Rps. acidophila Ac 10050 indicates that this motif might be important for the precise structural arrangement of the native complex and fine tuning of its spectroscopic properties.

Determination of microscopic binding constants at individual DNA base sequences for the minor groove binders Hoechst 33258, DAPI and pentamidine

Footprinting titration experiments have been used to estimate microscopic binding constants (KA) for interactions of the ligands Hoechst 33258, DAPI and pentamidine with the 167-mer of the EcoRl-Rsal restriction fragment of the plasmid pBR322. The symmetric base sequence AATTAA yielded the lowest KA values while binding sites which contain an AAA-segment displayed higher binding constants. The accommodation of an adjacent G-C base pair to the ATTT-sequence does not significantly interfere with the stability of the DNA-drug complex. The footprint pattern of the compound Hoechst 33258 shows a peculiarity. Complex formation at low drug concentrations (up to 0.5 mu M) is accompanied by distinct protection sites in the DNA fragment against DNAasel digestion, while at higher drug concentration (up to 5.0 mu M) at the same sites the cleavage activity of the enzyme is enhanced. This is discussed in terms of a conformational change of DNA induced by two concentration-dependent binding modes (AT-specific minor groove binding at low drug concentration and GC-specific interaction at a higher one).

MR monitoring of focused ultrasonic surgery of renal cortex: experimental and simulation studies

The aim of the study was to test the hypothesis that magnetic resonance (MR) imaging-guided and -monitored noninvasive ultrasonic surgery can be performed in highly perfused tissues from outside the body. A simulation study was performed to evaluate the optimal sonication parameters. An MR-compatible positioning device was then used to manipulate a focused ultrasound transducer in an MR imager, which was used to sonicate kidneys of five rabbits at various power levels and different durations. Temperature elevation during sonication was monitored with a T1-weighted spoiled gradient-echo sequence. The simulation study demonstrated that a sharply focused transducer and relatively short sonication times (30 seconds or less) are necessary to prevent damage to the overlying skin and muscle tissue, which have a much lower blood perfusion rate than kidney. The experiments showed that the imaging sequence was sensitive enough to show temperature elevation during sonication, thereby indicating the location of the beam focus. Histologic evaluations showed that kidney necrosis could be consistently induced without damage to overlying skin and muscle. The study demonstrated that highly perfused tissues such as the renal cortex can be coagulated from outside the body with focused ultrasound and that MR imaging can be used to guide and monitor this surgery.

Scanning force microscopy of microtubules and polymorphic tubulin assemblies in air and in liquid

We have investigated microtubules (MTs) and polymorphic assemblies, formed in vitro from isolated microtubule protein, by scanning force microscopy (SFM) in air and in liquid. Immobilization of MTs was achieved by placing a drop of the assembly solution on a polylysine-coated coverslip. After washing with taxol and air drying, the characteristic microtubular fibrous morphology appeared in the SFM. The MTs formed a network similar to that obtained by transmission electron microscopy (TEM). A height of approximately 9.5 nm for dried MTs was computed from the surface topography. Glutaraldehyde fixation of the MTs yielded higher structures (approximately 14 nm), which swelled to approximately 20 nm after rehydration, a value close to the MT diameter of approximately 25 nm determined from TEM images of ultrathin sections. The protofilament pattern of the MTs and surface attached MT-associated proteins were not apparent from SFM, although the height along the long axis of the MTs appeared slightly modulated. In addition to MTs, various polymorphic tubulin assemblies including ribbons, hoops and double-walled MTs were visualized by SFM.

MR imaging of the retroperitoneum

The multiplanar and soft-tissue capabilities of MR imaging make it a valuable diagnostic tool for the retroperitoneal space and its organs. In addition, by virtue of its location, the retroperitoneum is well suited for study by this modality. Appropriate techniques, including the use of contrast, are discussed as are the normal and pathologic appearances of the organs and areas of the retroperitoneum.

Toluene abuse: physical basis for hypointensity of the basal ganglia on T2-weighted MR images

PURPOSE

To explain the hypointensity in the basal ganglia on T2-weighted magnetic resonance (MR) images of brains of toluene abusers.

MATERIALS AND METHODS

Eight patients with histories of toluene abuse underwent MR imaging. A bilayered model of dipalmitoylphosphatidylcholine (DPPC; 100 mmol/L concentration) and varying concentrations of toluene was formed. The DPPC control and toluene-mixed bilayers underwent MR imaging. T1 and T2 were measured as a function of toluene and lipid concentrations.

RESULTS

T2-weighted images of patients who had abused toluene showed marked hypointensity in the thalami and moderate hypointensity in the basal ganglia. Measurements of the DPPC-toluene phantom indicated that toluene-tainted lipid bilayers dramatically shortened T2 and had little effect on T1. By comparison, DPPC itself had little discernible effect on either T1 or T2.

CONCLUSION

This model suggests that partitioning of toluene into the lipid membranes of cells in cerebral tissue may be responsible for the hypointensity of basal ganglia noted on T2-weighted MR images of brains of toluene abusers.

The usefulness of a contrast agent and gradient-recalled acquisition in a steady-state imaging sequence for magnetic resonance imaging-guided noninvasive ultrasound surgery

RATIONALE AND OBJECTIVES

The ability of magnetic resonance imaging to detect small temperature elevations from focused ultrasound surgery beams was studied. In addition, the value of a contrast agent in delineating the necrosed tissue volume was investigated.

MATERIALS AND METHODS

Gradient-recalled acquisition in a steady state (GRASS) T1-weighted images were used to follow the temperature elevation and tissue changes during 2-minute sonications in the thigh muscles of 10 rabbits. The effects of the treatment on the vascular network was investigated by injecting a contrast agent bolus before or after the sonication.

RESULTS

The signal intensity decreased during the sonication, and the reduction was directly proportional to the applied power and increase in temperature. The signal intensity returned gradually back to baseline after the ultrasound was turned off. Injection of the contrast agent increased the signal intensity in muscle, but not in the necrosed tissue. The dimensions of the delineated tissue volume were the same as measured from the T2-weighted fast-spin-echo images and postmortem tissue examination.

CONCLUSIONS

These results indicate that magnetic resonance imaging can be used to detect temperature elevations that do not cause tissue damage and that contrast agent can be used to delineate the necrosed tissue volume.

In vitro production of proteoglycans in the articular-epiphyseal cartilage of growing pigs

The failure of cartilage mineralization in osteochondrotic cartilage may be due to an impaired proteoglycan production. The in vitro production of proteoglycans was therefore studied in the joint cartilage of growing pigs, aged 9-18 weeks, after incubation of cartilage samples with 35S-sulfate. Cartilage was obtained from different areas of the femoral condyles and samples from these areas were further divided into three layers, where the superficial layer contains articular cartilage and the basal layers consist of growth cartilage. There was no significant difference in the overall amount of 35S-proteoglycans synthesized in different areas of the condyles. However, the total production of 35S-proteoglycans per mg tissue was highest in the basal layer in all areas. This was not due to a larger number of cells; the superficial layer contained more DNA per mg tissue than the basal layer. Gel chromatography on Sepharose CL-2B of the cartilage extracts, which resulted in the separation of large proteoglycans (Kav approximately 0.4) from proteoglycans of small hydrodynamic size (Kav approximately 0.8), showed that the relative amount of large proteoglycans increased with the distance from the articular surface. Again, no difference in the relative amounts of large and small proteoglycans were found when cartilage from different areas were compared. Osteochondrotic cartilage was detected in the pigs aged 12-18 weeks. In areas where osteochondrotic cartilage were present, the total production of 35S-proteoglycans was lowered and the relative amount of large proteoglycans was less than that found in the adjoining areas devoid of osteochondrotic lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Gas-filled liposomes as echocardiographic contrast agents in rabbits with myocardial infarcts

RATIONALE AND OBJECTIVES

The authors evaluated gas-filled liposomes as echocardiographic contrast agents in rabbits with myocardial infarcts.

METHODS

Ten rabbits underwent ligation of the left anterior descending coronary artery. Five animals underwent echocardiography before and after production of myocardial infarct (MI) and four animals had post-MI imaging only. In either case, images were obtained before and after injection of a single dose of 1 mL of gas-filed liposomes. Three radiologists blinded to clinical information reviewed the pre- and postcontrast images and assessed endomyocardial border definition, wall motion, confidence levels for normal versus abnormal wall motion and visualization of papillary muscle and mitral valve.

RESULTS

Postcontrast scans showed significant improvement (P < .05) in endomyocardial border definition, visualization of wall motion, papillary muscle and mitral valve as well as increased reader confidence level.

CONCLUSIONS

These results are encouraging and suggest that gas-filled liposomes may be a useful contrast agent for echocardiography.

Manganese-based liposomes. Comparative approaches

RATIONALE AND OBJECTIVES

The purpose of this study was to further develop and compare manganese-based liposomes prepared by two different approaches wherein a manganese ion was entrapped within the internal aqueous space of the vesicles or into the bilayer surface via membrane bound complexes.

METHODS

Small unilamellar liposomes (SUVs) were prepared entrapping manganese chloride. Alkylated complexes of manganese were prepared and also incorporated into SUVs. The two different manganese-based liposomes were compared for in-vitro relaxivity, stability, toxicity, and in-vivo imaging in rats with liver tumors.

RESULTS

Liposomes entrapping manganese had a concentration-dependent change in relaxivity that was maximal at a several-fold molar excess of phospholipid relative to manganese ion. Liposomes bearing membrane-bound complexes showed relaxivity inversely proportional to vesicle size. In-vivo imaging showed greater and more specific hepatic enhancement with manganese liposomes bearing alkylated complexes than those entrapping manganese ion.

CONCLUSIONS

Correlation effects likely explain the increased relaxivity of manganese entrapped in phospholipid vesicles. Greater efficacy, however, is afforded by liposomes bearing alkylated complexes.

Dominant Negative Mutants of Opaque2 Suppress Transactivation of a 22-kD Zein Promoter by Opaque2 in Maize Endosperm Cells

In maize endosperm, genes encoding the 22-kD zein class of storage proteins are regulated by the OPAQUE2 locus. The Opaque2 (O2) protein shares homology with the basic domain/leucine zipper class of transcriptional activators. Using microprojectile bombardment, we have shown that O2 is capable of transactivating a 22-kD zein promoter in maize endosperm suspension cultures and in longitudinal sections of intact endosperm. Two mutant forms of the O2 gene were constructed by deleting regions that encode either the basic domain or the first 175 N-terminal residues of the O2 protein. When either of these mutant O2 genes was coexpressed with wild-type O2 in a maize endosperm expression system, O2-mediated transactivation of the 22-kD zein promoter was inhibited specifically and in a dose-dependent manner. Electrophoretic mobility shift assays and immunoprecipitation studies indicated that the mutant O2 proteins form heterodimers with wild-type O2 in vitro. The mutant lacking the basic domain forms heterodimers with wild-type O2, which can no longer bind DNA. In contrast, the product of the N-terminal truncation allele forms homodimers and heterodimers with wild-type O2, both of which can still bind DNA. Because the N-terminal region contains an activation domain, it is likely that these latter complexes are deficient in transactivation. Dominant negative inhibitors of gene expression, such as those constructed here, provide an alternative to antisense RNA approaches for inactivation of gene function in plants.

Effects of the fluorescence dye DAPI on microtubule structure in vitro: formation of novel types of tubulin assembly products

It has been found that the DNA fluorescence dye 4',6-diamidino-2-phenylindole (DAPI) is able to stain also microtubules. However, electron microscopy revealed that DAPI changed microtubule structure and induced the formation of a broad spectrum of polymorphic tubulin assembly products. Upon addition of DAPI to microtubules assembled from 10 to 15 mumol tubulin (molar DAPI/tubulin ratios of 10 to 40) in the presence of microtubule-associated proteins, most of the microtubules were decorated with additional protofilaments usually running parallel to the protofilaments of the microtubule wall (microtubule-protofilament complexes). When DAPI was already present during assembly, curved C- and S-shaped protofilament ribbons and microtubule-ribbon complexes with 6-shaped profiles were the most prominent products, beside microtubules. Additionally, protofilament bundles, some flat sheets, and hoops occurred. Electrophoresis revealed that DAPI lowered the amount of associated proteins, especially of tau-proteins, bound to the assembly products. Nevertheless, DAPI stimulated the assembly, enabled pure tubulin to assemble even at concentrations as low as 10 mumol, and stabilized the assembly products against cold. The microtubule-protofilament complexes, observed for the first time, are interpreted as the result of DAPI-induced protofilament linking as well as of activation of an additional tubulin-tubulin binding site which is possibly identical to that involved in the formation of microtubule doublets.