Evidence for linkage of bipolar disorder to chromosome 18 with a parent-of-origin effect

A susceptibility gene on chromosome 18 and a parent-of-origin effect have been suggested for bipolar affective disorder (BPAD). We have studied 28 nuclear families selected for apparent unilineal transmission of the BPAD phenotype, by using 31 polymorphic markers spanning chromosome 18. Evidence for linkage was tested with affected-sib-pair and LOD score methods under two definitions of the affected phenotype. The affected-sibpair analyses indicated excess allele sharing for markers on 18p within the region reported previously. The greatest sharing was at D18S37: 64% in bipolar and recurrent unipolar (RUP) sib pairs (P = .0006). In addition, excess sharing of the paternally, but not maternally, transmitted alleles was observed at three markers on 18q: at D18S41, 51 bipolar and RUP sib pairs were concordant for paternally transmitted alleles, and 21 pairs were discordant (P = 0004). The evidence for linkage to loci on both 18p and 18q was strongest in the 11 paternal pedigrees, i.e., those in which the father or one of the father's sibs is affected. In these pedigrees, the greatest allele sharing (81%; P = .00002) and the highest LOD score (3.51; phi = 0.0) were observed at D18S41. Our results provide further support for linkage of BPAD to chromosome 18 and the first molecular evidence for a parent-of-origin effect operating in this disorder. The number of loci involved, and their precise location, require further study..

Yttrium-90 chimeric L6 therapy of human breast cancer in nude mice and apoptosis-related messenger RNA expression

Radioimmunotherapy (RIT) in breast cancer patients using I-131-chimeric L6 (ChL6) and in human breast cancer xenografts in nude mice using Y-90-1,4,7,10-tetraazacylododecant N,N',N",N"'-tetraacetic acid-peptide ChL6 (Y-90-ChL6) has shown promise. Tumor cell response to low-dose rate (5-25 rads/h) irradiation from Y-90-ChL6 RIT, therefore, was correlated with levels of tumor cell mRNA for selected genes linked to programmed cell death (apoptosis). Three groups of 10-16 mice with 1-2 HBT 3477 xenograft tumors were treated with 100, 150, or 250 microCi Y-90-ChL6. Three tumors were taken before and two tumors each were taken 3, 6, and 24 h after injection of 150 microCi Y-90-ChL6. Tumor expression of mRNA was amplified by PCR for p53, PIC1, c-myc, and transforming growth factor-beta 1; quantitated; and standardized to N-ras. Tumors received radiation doses of 2000, 3000, and 5000 rads, respectively, for the groups of mice that received 100, 150, and 250 microCi Y-90-ChL6, and tumor regression occurred in each group, with mean tumor volumes decreased by 10, 50, and 95% at nadir after Y-90-ChL6 injection. At the highest dose level, 30% of mice had complete remissions, and no treatment deaths occurred, although tumors subsequently recurred. Continuous up-regulation of transforming growth factor-beta 1 and c-myc mRNA expression was observed from 3 to 24 h after treatment. Expression of p53 and PIC1 increased at 3 h and subsequently decreased to the untreated control levels. These observations are consistent with previous observations of early responses of p53 and PIC1 to cellular DNA damage and subsequent G1 cell cycle arrest or apoptosis. Apoptosis-associated gene expression patterns observed in this tumor model provide evidence that changes are initiated in the first 24 h of RIT associated with radiation doses of 100-700 rads. These preliminary data suggest that insight into the molecular basis of RIT-induced tumor regression may be gained by further studies using different radiation doses.

Expression of multiple forms of brain cytochrome P450

Multiple forms of cytochrome P450 (P450) in brain tissue have been demonstrated to be expressible in brain tissue using polymerase chain reaction (PCR) techniques, Northern blotting, hydroxylation activity assessment and cloning approaches. The antidepressant drug imipramine is metabolized by brain microsomes to multiple products by pathways inhibitable by quinidine, 7,8-benzoflavone, and ketoconazole, well-known inhibitors of P450-catalyzed reactions. Moreover, PCR studies revealed that a number of P450s are expressible in brain tissue and in glioma C6 cells. Quantitative PCR studies further demonstrated the response of many of these forms to induction in agreement with hydroxylation activity results.

Functional assessment of specific amino acid residues of cytochrome P4501A1 using anti-peptide antibodies

Several positively charged amino acid residues in cytochrome P450 have been shown to be involved in the electrostatic association with NADPH-cytochrome P450 reductase. For cytochrome P4501A1, five regions were proposed as the putative binding sites for the reductase (Shen, S., and Strobel, H. W. (1993) Arch. Biochem. Biophys. 304, 257-265). To elucidate the specific roles of each of these amino acid residues, five anti-peptide antibodies defined as 1A, 4A, 5A, 6A, and 7A were generated against these regions containing 8-13 amino acids and were affinity-purified using a peptide-Sepharose 4B column. Analysis by enzyme-linked immunosorbent assay and protein immunoblot techniques demonstrated that three of five anti-peptide antibodies have specific binding to the peptides as well as to cytochrome P4501A1. Incubation of the various anti-peptide antibodies with cytochrome P450 followed by reconstitution with reductase, lipid, and NADPH resulted in significant inhibition of P450 activity for antibodies 5A and 6A, but not for 1A, 4A, or 7A. Antibody 5A also exhibited inhibition of P450 activity supported by cumene hydroperoxide, though the inhibition was 45 to 30% less than the inhibition of reductase-supported activity at each of the increasing concentrations of antibody. Kinetic studies with antibody 5A revealed no change in the Km for the substrate ethoxycoumarin, but rather a dramatic effect on the Vmax of the cytochrome P4501A1 system whether reconstituted with reductase or supported by cumene hydroperoxide. Characterization of the effects of antibody 5A on cytochrome P4501A1 suggested that the binding of antibody 5A to P4501A1 may change the binding of P4501A1 with reductase. Furthermore, the binding of 5A to cytochrome P4501A1 also lowered the Vmax of the P450. These results are consistent with the roles for the regions of cytochrome P4501A1 from amino acid residues 269 to 281 (peptide 5) and 454 to 463 (peptide 6) in cytochrome P4501A1 hydroxylation activity.

Design and synthesis of new naphthalenic derivatives as ligands for 2-[125I]iodomelatonin binding sites

New melatonin-like agents were designed from the frameworks of 2,5-dimethoxyphenethylamine, an important structural moiety for the 5-HT receptor, and (2-methoxynaphthyl)-ethylamine. The compounds were synthesized by classical methods and evaluated in binding assays with chicken brain membranes using 2-[125I]iodomelatonin as the radioligand. Preliminary studies on the series of N-acyl-disubstituted phenethylamines showed the favorable role of the methoxy group in the ortho position of the side chain on the affinity for the receptor (Ki = 8 +/- 0.2 nM) for N-[2-(2-methoxy-5-bromophenyl)ethyl]propionamide (3o). This effect was confirmed in a series of the naphthalene derivatives, a bioisosteric moiety of the indole ring, and several potent ligands for melatonin binding sites were prepared such as N-[2-(2-methoxynaphthyl)ethyl]propionamide (4b) (Ki = 0.67 +/- 0.05 nM) and N-[2-(2,7-dimethoxynaphthyl)ethyl]cyclopropylformamide (Ki = 0.05 +/- 0.004 nM) (4k). Structure-activity relationships are discussed with regard to melatonin and bioisosteric naphthalenic compound 2. The Ki value for 4b was affected to a similar extent to that of melatonin by GTP-gamma-S or Mn2+ in competition experiments, suggesting an agonist profile for this compound.

Denaturation of cytochrome P450 2B1 by guanidine hydrochloride and urea: evidence for a metastable intermediate state of the active site

A metastable intermediate was found in the course of the denaturation of purified cytochrome P450 2B1 by increasing concentrations of guanidine hydrochloride (GuHCl). The metastable intermediate has no or low absorbance at 450 nm in the reduced carbon monoxide difference spectrum and has no absorbance at 420 nm. The intermediate is easily converted to P420 by increasing concentrations of GuHCl. Before it becomes P420, the cytochrome can be completely reconverted to native P450 by dilution and incubation at 4 degrees C. Cytochrome P420 resulting from exposure to higher concentrations of GuHCl (> 3 M) failed to be reconverted to P450 by dilution. Denaturation of P450 2B1 by exposure to low concentrations of urea (< 2 M) is also completely reversible but no obvious intermediate is detectable. An intermediate is observed, however, when the urea denaturation is conducted in the presence of 1 M NaCl. As is the case with higher concentrations of GuHCl, cytochrome P450 denatured by exposure to 5 M or higher concentrations of urea is not reversible. The failure of reconversion of P420 denatured by exposure of cytochrome P450 to high concentrations of GuHCl or urea is probably attributable to the extensive unfolding of the apoprotein, which favors aggregation, rather than to heme loss. Our results also suggest that the active site is more sensitive to denaturants than other regions of the protein.

Estimation of radiation absorbed doses to the red marrow in radioimmunotherapy

Myelotoxicity is the dose-limiting factor in radioimmunotherapy. Traditional methods most commonly used to estimate the radiation adsorbed dose to the bone marrow of patients consider contributions from radionuclide in the blood and/or total body. Targeted therapies, such as radioimmunotherapy, add a third potential source for radiation to the bone marrow because the radiolabeled targeting molecules can accumulate specifically on malignant target cells infiltrating the bone marrow. A non-invasive method for estimating the radiation absorbed dose to the red marrow of patients who have received radiolabeled monoclonal antibodies (MoAb) has been developed and explored. The method depends on determining the cumulated activity in three contributing sources: 1) marrow; 2) blood; and 3) total body. The novel aspect of this method for estimating marrow radiation dose is derivation of the radiation dose for the entire red marrow from radiation dose estimates obtained by detection of cumulated activity in three lumbar vertebrae using a gamma camera. Contributions to the marrow radiation dose from marrow, blood, and total body cumulated activity were determined for patients who received an I-131 labeled MoAb, Lym-1, that reacts with malignant B-lymphocytes of chronic lymphocytic leukemia and nonHodgkin's lymphoma. Six patients were selected for illustrative purposes because their vertebrae were readily visualized on lumbar images. The radiation doses to the marrow contributed by nonpenetrating emissions in the marrow blood and penetrating emissions in the total body were similar in these patients with a mean of 0.2 and 0.3 rads per administered mCi from the blood and total body, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunohistochemical staining for endotoxin using horseshoe crab factor C in fecal peritonitis

The object of the present study was to apply a new immunohistochemical staining method to the in vivo determination of endotoxin localization. The immunohistochemical staining method requires factor C (an initiation factor in the Limulus clotting system which is mediated by endotoxin) as a specific ligand of endotoxin, and a newly developed murine monoclonal antibody to factor C. The blood endotoxin level and endotoxin localization in the rat were determined before and at 6, 12 and 24 h after intraperitoneal injection of 0.25 g/kg of fresh rat feces. The greatest blood endotoxin level was achieved at 12 h after the injection, and uptake of endotoxin was evident in Kupffer cells in the liver at 24 h after the injection. There has been no report on determining endotoxin localization in cases of endotoxemia attributed to fecal peritonitis. This new immunohistochemical staining method for determining endotoxin localization will contribute to the histopathological diagnosis of endotoxemia in humans.

Structure and oxygen sensitivity of nifLA promoter of Enterobacter cloacae

The nucleotide sequence of the nifLA promoter of Enterobacter cloacae E26 was determined, and the transcription start site of nifLA was mapped by the primer extension. Studies on the oxygen regulation of E. cloacae nifLA promoter with the nifL'-lacZ fusion showed that the nifLA promoter was sensitive to oxygen as Klebsiella pneumoniae nifLA promoter reported previously. Comparison between the nifLA promoter sequences of E. cloacae and K. pneumoniae revealed the presence of an 11-bp conserved sequence between the -24/-12 consensus of sigma 54-dependent promoter and NtrC binding motif. The 11-bp sequence is speculated to be involved in the oxygen regulation of the nifLA promoter of both enteric bacteria.

Molecular epidemiology of human rotaviruses in Manipur: genome analysis of rotaviruses of long electropherotype and subgroup I

In 1987/88 a winter outbreak of infantile gastroenteritis occurred in Manipur, India which was mainly due to rotaviruses of long electropherotype and subgroup (SG) I. The VP7 gene of one of these viruses (M48) has been cloned and sequenced. It was found to be very closely related to the VP7 genes of the G2 serotype human rotaviruses RV-5 and S2. Follow-up epidemiology of this event in Manipur during 1989-1992 yielded mainly rotaviruses of more conventional characteristics (94 isolates of SG II and long electropherotype, and 90 isolates of SG I and short electropherotype), but also 6 isolates of SG I with long electropherotype, indicating that these viruses continue to circulate in the Manipur community. One isolate of short electropherotype was of subgroup II, and one long electropherotype isolate reacted with the group A but not with either the subgroup I or subgroup II monoclonal antibodies.

Quantitative bremsstrahlung imaging of yttrium-90 using a Wiener filter

Yttrium-90 (90Y), a pure beta emitter, is an attractive radionuclide for radioimmunotherapy of cancer. Therapeutic management requires quantitative imaging to measure the pharmacokinetics of the radionuclide in the patient for radiation dosimetric calculations. The bremsstrahlung emissions can be utilized to acquire an image of beta sources using a gamma camera. Quantitation of 90Y by bremsstrahlung imaging is difficult because of poor image quality that results from septal penetration and scatter secondary to the broad bremsstrahlung energies. In this work, quantitative methods for bremsstrahlung imaging of 90Y sources that involved the use of (a) a Wiener filter to deconvolve the septal penetration and scatter while suppressing image noise, and (b) the geometric mean of the conjugate view (GM) and effective point source (EPS) methods to quantify activities were investigated. An abdominal phantom was prepared with 90Y activities in the liver, spleen, tumors, and background volumes that were similar to those observed in patient studies. A twofold improvement in resolution recovery for full width at tenth maximum of the line spread function at 11 cm depth in water was achieved using Wiener restoration. Definition of the organ and tumor edges was greatly enhanced and cross talk between adjacent sources was suppressed after Wiener restoration. These improvements in image quality led to more accurate estimation of organ and tumor activities. Using the optimum attenuation correction method for GM and EPS quantitation of filtered bremsstrahlung images, estimates of individual activities (< or = 17% error) and cumulated activities (< or = 8% error) in all of the sources were accurate except for a tumor of 2 cm diameter. The results of this study provide the basis for a method to quantify beta source distribution and demonstrate the potential use of bremsstrahlung imaging in clinical settings.

Ectopic expression of Hoxb-8 causes duplication of the ZPA in the forelimb and homeotic transformation of axial structures

Transgenic embryos were generated carrying a Hoxb-8 transgene under control of the mouse RAR beta 2 promoter, which extends the normal expression domain to more anterior regions of the embryo. These embryos showed mirror-image duplications in the forelimb, analogous to the duplications observed in chick in response to transplantation of a ZPA to the anterior margin of the limb bud. Examination of Sonic hedgehog, Fgf-4, and Hoxd-11 gene expression confirmed that a second ZPA had been generated at the anterior side of the limb bud. Besides other alterations, posterior homeotic transformations of axial structures were observed, involving the first spinal (Froriep's) ganglion and several cervical vertebrae.

Planar gamma camera imaging and quantitation of yttrium-90 bremsstrahlung

Yttrium-90 is a promising radionuclide for radioimmunotherapy of cancer because of its energetic beta emissions. Therapeutic management requires quantitative imaging to assess the pharmacokinetics and radiation dosimetry of the 90Y-labeled antibody. Conventional gamma photon imaging methods cannot be easily applied to imaging of 90Y-bremsstrahlung because of its continuous energy spectrum.

METHODS

The sensitivity, resolution and source-to-background signal ratio (S/B) of the detector system for 90Y-bremsstrahlung were investigated for various collimators and energy windows in order to determine optimum conditions for quantitative imaging. After these conditions were determined, the accuracy of quantitation of 90Y activity in an Alderson abdominal phantom was examined.

RESULTS

When the energy-window width was increased, the benefit of increased sensitivity outweighed degradation in resolution and S/B ratio until the manufacturer's energy specifications for the collimator were exceeded. Using the same energy window, we improved resolution and S/B for the medium-energy (ME) collimator when compared to the low-energy, all-purpose (LEAP) collimator, and there was little additional improvement using the high-energy (HE) collimator. Camera sensitivity under tissue equivalent conditions was 4.2 times greater for the LEAP and 1.7 times greater for the ME collimators when compared to the HE collimator. Thus, the best, most practical selections were found to be the ME collimator and an energy window of 55-285 keV. When we used these optimal conditions for image acquisition, the estimation of 90Y activity in organs and tumors was within 15% of the true activities.

CONCLUSIONS

The results of this study suggest that reasonable accuracy can be achieved in clinical radioimmunotherapy using 90Y-bremsstrahlung quantitation.

Probing the putative cytochrome P450- and cytochrome c-binding sites on NADPH-cytochrome P450 reductase by anti-peptide antibodies

Two regions (amino acid residues 110-130 and 204-218) of NADPH-cytochrome P450 reductase (reductase) have been shown to be the putative binding sites for the interaction with cytochrome P450 or cytochrome c. To obtain further insight into the molecular mechanism of protein-protein interaction between these proteins, three anti-peptide antibodies (1A, 2A, and 3A) were generated against the peptides corresponding to these two regions on rat reductase to study the interaction between the reductase and cytochrome P450 or cytochrome c. All three anti-peptide antibodies have high affinity for their peptide antigens on ELISA (titre > 1 x 10(-6) g/L), and they also bind to rat reductase on ELISA under both denatured and native conditions, suggesting that these regions are on the surface of the protein. 1A and 3A also bind to rabbit and human reductase, though 1A binds to human reductase with lower affinity. Antibody 2A does not bind to rabbit or human reductase. Western blot analysis using these anti-peptide antibodies showed similar results. Antibodies 1A and 3A inhibit both cytochrome P4501A1-dependent ethoxycoumarin hydroxylation activity and P4502B1-dependent pentoxyresorufin dealkylation activity, but the inhibition by 1A and 3A was not additive. Antibodies 1A and 3A also have inhibitory effects on the activity of P4501A1-dependent ethoxycoumarin hydroxylation reconstituted with reductase from rabbit and human. However, none of the three anti-peptide antibodies inhibits cytochrome c reduction by rat reductase. These data suggest that reductases from rat, rabbit, and human share similar structure in at least two regions which appear to be on the surface of the protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Rearrangement of the VP6 gene of a group A rotavirus in combination with a point mutation affecting trimer stability

A group A rotavirus isolated from a lamb with diarrhea in Qinhai province, China, was serially passaged in fetal calf kidney cells. In passage 96, rearrangements of RNA segments 5 and 6 of the viral genome were found. Here we report the nucleotide and predicted amino acid sequences of normal and rearranged RNA 6, coding for the major inner capsid protein VP6. In comparison with the normal gene (N6), the rearranged RNA 6 (R6) contained the normal open reading frame followed by a 473-nucleotide (nt) duplication of the gene beginning 23 nt after the termination codon. The duplicated region starts at nt 768 and runs through to the 3' end of the gene. In accordance with the nucleotide sequence of the rearranged RNA 6, a normal-length VP6 product was found in cells infected with the mutant. However, a single-amino-acid change from proline to glutamine at position 309 slightly affected the electrophoretic mobility of the VP6 monomer of the R6 mutant and reduced the stability of VP6 trimers on gels and at low pH values compared with the normal gene product. The degree of relatedness of VP6 of the Chinese lamb rotavirus Lp14 to those of other group A rotaviruses was determined.

Comparative toxicity studies of yttrium-90 MX-DTPA and 2-IT-BAD conjugated monoclonal antibody (BrE-3)

BACKGROUND

BrE-3 is monoclonal antibody that has promise for imaging and therapy of human adenocarcinoma. Because of observations in therapeutic trials of yttrium-90 (90Y) escape from radioimmunoconjugates and uptake by the skeleton with resultant bone marrow toxicity, the authors attempted to evaluate the importance of this factor by a comparison of the LD50 in healthy mice treated with 90Y that had been chelated with either of two high affinity chelators, methylbenzyldiethylene-triaminepentaacetic acid (MX-DTPA) or bromoacetamidobenzyl-1,4,7,10-tetraazocyclododecane- N,N',N'',N'''-tetraacetic acid (BAD).

METHODS AND RESULTS

Bone marrow hematopoietic toxicity was dose-limiting and the source of death for both chelators. The LD50 for 90Y-BrE-3-MX-DTPA was 220.9 microCi, and that for 90Y-BrE-3-2IT-BAD and was 307.8 microCi. Whole-body autoradiography revealed substantially greater uptake of 90Y in the skeleton when MX-DTPA was used as the chelator.

CONCLUSIONS

These observations suggest that 90Y escape to bone is a significant factor in the maximum tolerated dose of radioimmunoconjugate that can be used in therapeutic trials. These results probably underestimate the importance of 90Y escape since 90Y in the skeleton of patients is likely to be more significant than in mice because more of the 90Y energy is absorbed in the marrow of larger species.

Overview of radiation myelotoxicity secondary to radioimmunotherapy using 131I-Lym-1 as a model

The radiation dose-limiting toxicity from radioimmunotherapy has been myelotoxicity in the absence of bone marrow reconstitution (transplantation). Myelotoxicity can be assessed directly by biopsy examination of the bone marrow and indirectly by peripheral blood counts. In patients with B-cell malignancies, thrombocytopenia has been the initial and most severe manifestation of 131I-Lym-1 radiation toxicity from treatment. Manifestations of myelotoxicity varied greatly among the patients and from one treatment dose to another in the same patient, suggesting that additional factors were present. There was an increased likelihood of Grade 3-4 hematopoietic toxicity after 131I-Lym-1 treatment if the patient had peripheral blood cell abnormalities before undergoing 131I-Lym-1 treatment. Fractionation of the total 131I-Lym-1 dose was associated with less toxicity. In many patients, myelotoxicity could not be explained by marrow radiation dose (0.36 +/- 0.13 rads per administered mCi) from 131I-Lym-1 in the blood and body alone. Bone marrow examination and 131I-Lym-1 imaging usually provided evidence for additional marrow radiation from 131I-Lym-1-targeting of marrow malignancy and also for residual toxic effects from prior treatment in these patients. Immunohistologic and imaging examination of the bone marrow performed with the intended treatment antibody allowed assessment of extent of marrow malignancy and prediction of degree of myelotoxicity from subsequent treatment. Treatment programs (and protocols) for radioimmunotherapy should incorporate these methods into the decision process. Larger amounts of 131I-Lym-1 can be used in patients selected to have relatively normal peripheral blood cell counts and normocellular bone marrows uninvolved by the malignancy. These observations appear to be relevant to the maximum tolerated dose in radioimmunotherapy for other malignancies as well.

Ultrasonically assisted electrospray ionization for LC/MS determination of nucleosides from a transfer RNA digest

The use of an ultrasonic nebulizer to assist electrospray ionization mass spectrometry (ESI-MS) has been described and demonstrated with the analysis of a transfer RNA digest by microcolumn LC. The restricted range of mobile-phase compositions amenable to the electrospray process has traditionally placed a severe limitation on the types of LC applications that can be used with ESI-MS. For this reason, an ultrasonic nebulizer configured for LC has been developed that can generate the fine dispersion of liquid required for ESI-MS from any type of mobile phase. In the case presented here, a transfer RNA was enzymatically digested into its substituent nucleosides, which were then analyzed by microcolumn LC. The required mobile-phase gradient (beginning at 5% methanol) falls outside the solvent range that can be used with conventional electrospray. The ultrasonic nebulizer, however, resolves this problem. The fundamental behavior of the four most common nucleosides (cytidine, adenosine, guanosine, uridine) was studied, and conclusions concerning the effects of solution chemistry were drawn. Specifically, signal from the H+ adducts of these species seems to be strongly dependent on the pKa value. Also, effects from several source operating variables were examined. These included capillary exit voltage, drying and focusing gases, and nebulizer frequency. Performance was found to be consistent over a wide range (0-100% methanol) of mobile-phase compositions. The limit of detection for adenosine injected onto a microcolumn was found to be 100 amol. Finally, nucleosides from as little as 150 fmol of RNA (amount prior to digestion) could be detected.

An optoelectronic registration method as applied to PAF-mediated hydrogen peroxide induced arterial thrombosis

In the present paper, a standardized method for the induction and registration of platelet thrombi in arterioles (500 microns diameter) of small laboratory animals is described in full detail. Using an optoelectronic analogue computer device, different discriminating parameters characteristic for the thrombotic phenomenon are presented. As the topical application of exogenous PAF-acether induces the generation of endogenous PAF-acether according to previous investigations (Bourgain et al. (1985) Prostaglandins 30, 185) it was deemed interesting to investigate the effect of hydrogen peroxide using the described methodology. It was found that the latter substance not only primes the effect of PAF-acether-induced thrombosis, but also can trigger by itself PAF-acether modulated arterial thrombus formation. Experimental evidence is adduced that these thrombotic phenomena can be most efficiently down regulated by specific PAF-acether antagonists.

beta 2-Microglobulin amyloidosis: illustrative cases

Patients on long-term dialysis tend to develop amyloidosis derived from beta 2-microglobulin. Serum levels of this protein rise in renal insufficiency and remain high in patients on dialysis. The distribution of amyloid deposits in such patients as well as tissue diagnosis, immunohistochemistry, and electron microscopic features are briefly discussed.

Determination of the relative percentage deuteration of the ribosomal protein S4 by electrospray ionization mass spectrometry

Electrospray ionization mass spectrometry provides a fast, economical, and accurate new method for determining levels of nonexchangeable deuterium incorporation in proteins derived from organisms grown on deuterated media. Results are shown for determining the percentage deuteration of ribosomal protein S4 from Escherichia coli.

Immunoglobulin light chains and the kidney: an overview

Monoclonal immunoglobulins and free immunoglobulin light chains are produced by plasma cells as a result of their clonal expansion in plasma cell dyscrasia. These proteins are pivotal in the development of pathologic and clinical symptoms of plasma cell dyscrasia and renal manifestations are frequently the presenting and leading features of this process. The spectrum of pathology associated with monoclonal light chains includes light-chain cast nephropathy and tissue deposits derived from the monoclonal light chain, ie, amyloid derived from the light chains and nonamyloidotic light chain deposition disease. The main diagnostic features, differential diagnosis, and pathogenesis are briefly reviewed.

Nucleotide sequences of the VP4 and VP7 genes of a Chinese lamb rotavirus: evidence for a new P type in a G10 type virus

The VP7 and VP4 genes of a group A rotavirus (Lp14) isolated from a lamb with diarrhea in Qinhai province, China, in 1981 were reverse transcribed, amplified by PCR, cloned, and sequenced. The virus was found to possess a VP7 gene, classifying it as a G10 type, and a VP4 gene which showed only limited homology with any other known VP4 gene, suggesting its classification as a new P type and providing further evidence for the vast diversity of group A rotaviruses.

[Role of nucleus accumbens in cardiovascular activities and its relationship with opioid peptides in rats]

In this study, electrical stimulation and microinjection in nucleus accumbens in urethane-anesthetized rats were conducted to observe the effect of electrical stimulation of nucleus accumbens on blood pressure and heart rate. The following results were observed: (1) Electrical stimulation of the nucleus accumbens of rat resulted in significant hypotension and bradycardia. (2) Kainic acid microinjected into the nucleus accumbens, could abolish the effects mentioned above. (3) Naloxone administered to the nucleus accumbens could block the cardiovascular inhibitory effect evoked by electrical stimulation of nucleus accumbens. The intra-accumbens injection of mu-receptor agonist, DAGO could also elicit hypotension and bradycardia to an extent comparable to that of the effect due to electrical stimulation, whereas kappa-receptor agonist, U-50 had no such an effect. (4) When the cardiovascular inhibitory effect elicited by electrical stimulation of the nucleus accumbens was observed, the discharge activity in locus ceruleus was also decreased. (5) Bilateral vagotomy could abolish the change in heart rate elicited by the electrical stimulation of nucleus accumbens, but not the hypotension. It is suggested that the mu-opioid receptors of neurons in nucleus accumbens are involved in cardiovascular activity.

Role of lysine and arginine residues of cytochrome P450 in the interaction between cytochrome P4502B1 and NADPH-cytochrome P450 reductase

Chemical modification of cytochrome P450 was used to study the involvement of lysine and arginine residues in the interaction between cytochrome P450 and NADPH-cytochrome P450 reductase. Acetylation of 2.2 and 8.5 mol of lysine/mole of P450 by acetic anhydride led to 38.7 and 95% reductions, respectively, in benzphetamine demethylation activity by NADPH-dependent reconstituted P450/reductase complex, while modification of up to 8.5 mol of lysine/mol of P450 did not inhibit cumene hydroperoxide-supported P450-dependent benzphetamine demethylation. Acetylation of lysine residues by acetic anhydride does not grossly disturb the P450 protein conformation as revealed by absolute, CO-difference and fluorescence spectral studies. Modification of P4502B1 by acetic anhydride did not affect its substrate binding ability either. Lysine residues of P4502B1 putatively involved in the interaction with reductase have been identified by radiolabeling of lysine residues with [14C]acetic anhydride followed by trypsin digestion, HPLC separation, and amino acid microsequencing. Radiolabeled lysines occur at positions 251, 384, 422, 433, and 473. Modification of arginine residues in P4502B1 with phenylglyoxal and 2,3-butanedione seemed to have no significant effect on the benzphetamine demethylation activity of P4502B1 either reconstituted with reductase and NADPH or supported by cumene hydroperoxide. Studies of incorporation of [14C]phenylglyoxal showed no concentration- or time-dependent incorporation of phenylglyoxal into the P4502B1. These results support the hypothesis of a predominant role of lysine residues of P450 in the electrostatic interaction with NADPH-cytochrome P450 reductase.

A preliminary study of the fixation mechanism of collagen reaction with a polyepoxy fixative

A new biomaterial has been developed by fixing native collagens with a polyepoxy compound (PC) fixative. Prior studies have shown that this biomaterial has comparable properties as compared to collagen fixed with glutaraldehyde (GA) and thus has a great promise for use as an implantable bioprosthesis. The purpose of this study was to understand the mechanism of the amino acids-PC reactions in the fixation process. Bovine arteries were fixed with PC under various pH, concentration and temperature conditions as a function of fixation time. Individual amino acid components in the fresh and the fixed arteries were assayed using a Beckman amino acid analyzer to determine the degree of tanning. The denaturation temperature (Td) was also measured on each sample. Since the denaturation temperature is a direct indication of cross-linking of individual amino acids with the fixative, the difference in the degree of tanning for the same increase in Td may be indicative of the quantity of the masked, non-cross-linked amino acids. The fixation reaction data indicated that not all amino acids were cross-linked upon contacting the PC fixative. Masking appeared to be more substantial with a fixation at higher pH values.

Dominant negative retinoic acid receptor beta

Induction of the retinoic acid receptor beta 2 (RAR beta 2) gene by retinoic acid (RA) is mediated by a RA response element (RARE), which represents a high affinity binding site for RAR/RXR heterodimers acting at this site as RA-inducible transcription activators. In RA resistant RAC65 cells, RAR beta 2 induction is blocked due to expression of a truncated RAR alpha acting as a dominant negative repressor. Here we show that exogenous expression of RAR but not RXR can restore RA-dependent RAR beta 2 promoter activation in RAC65 cells. Structure-function analysis of hRAR beta 2 mutants in RAC65 cells shows, that the transactivation function required to restore RAR beta 2 promoter activation is dependent on the DNA binding, dimerization and RA-dependent transactivation properties of hRAR beta 2, which are retained in a mutant (beta delta 409) lacking the F domain. By contrast, dominant repression of RA-dependent mRAR beta 2 promoter activation by hRAR beta 2 mutants is independent of the DNA binding or RA-dependent transactivation function but requires a region (residues 204-384) in hRAR beta 2 involved in heterodimerization with RXR. These data extend previous observations on structure-function of RARs and provides tools for studying the role of retinoids and RARs during vertebrate development.

Kinetic study of collagen fixation with polyepoxy fixatives

A new biomaterial has been developed by fixing native collagen with a polyepoxy compound (PC) fixative. In this study, bovine internal thoracic arteries were fixed with PC under various conditions to help understand the kinetics of the collagen-PC reactions and optimize the fixation process. At predetermined time intervals, small samples were cut from the arteries to determine the quantities of the remaining unreacted amino acids in the collagen. Temperature, concentration, and solution pH were among the key parameters studied. The overall fixation rate was found to be reaction-rate controlled, as the rate of fixation was relatively slow compared with the rate of diffusion of PC. As might be expected, the reaction rate was favored by a higher temperature, concentration, and solution pH. A kinetic model, with a 2.5th reaction order with respect to the reactive functional groups of collagen and a first order with respect to PC, was developed that gave a good fit to the experimental data. Based on this model, the degree of fixation, X, as a function of time, t, is given by (1 - X)-1.5 = 1 + Kt, where K is a constant related to the initial concentrations and the reaction rate constant.

Embryonic stem cells stably transfected with mRAR beta 2-lacZ exhibit specific expression in chimeric embryos

Using the embryonic stem (ES) cell/chimera approach, we have studied the activity of the mouse retinoic acid receptor beta 2 (mRAR beta 2) promoter during ES cell differentiation and during embryonic development. Stable ES clones were isolated after introduction of a 1.8 kb mRAR beta 2-lacZ expression cassette. LacZ expression in these stable clones was specifically induced by retinoic acid (RA) in a similar fashion as the endogenous RAR beta 2 gene. Following introduction of three different ES clones into blastocysts, an integration-independent mRAR beta 2-lacZ expression pattern was obtained in chimeric embryos similar to that described by in situ hybridization and transgenic studies. Moreover, mRAR beta 2-lacZ expression was also detected at some additional sites not described before, e.g. body wall, ureter, mesonephric duct and optic stalk. Maternal RA administration at 8.5 days of pregnancy extended lacZ expression to more anterior and posterior regions. Transgenic mice were generated from germ-line transmission of the transfected ES cells; expression pattern and changes in expression upon RA induction in these transgenic embryos were identical to those in chimeric embryos. We conclude that by using the ES/chimera approach, the proximal 1.8 kb of the mRAR beta 2 promoter produces a reliable and reproducible expression pattern of the reporter gene, and that the ES cell/chimera approach is invaluable for the study of gene expression and regulation.

The role of cytochrome P450 lysine residues in the interaction between cytochrome P450IA1 and NADPH-cytochrome P450 reductase

Cytochrome P450IA1 (purified from hepatic microsomes of beta-naphthoflavone-treated rats) has been covalently modified with the lysine-modifying reagent acetic anhydride. Different levels of lysine residue modification in cytochrome P450IA1 can be achieved by varying the concentration of acetic anhydride. Modification of lysine residues in P450IA1 greatly inhibits the interaction of P450IA1 with NADPH-cytochrome P450 reductase. Modification of 1.0 and 3.3 mol lysine residues per mole P450IA1 resulted in 30 and 95% decreases, respectively, in 7-ethoxycoumarin hydroxylation by a reconstituted P450IA1/reductase complex. However, modification of 3.3 mol lysine residues per mole P450IA1 decreased only cumene hydroperoxide-supported P450-dependent 7-ethoxycoumarin hydroxylation by 30%. Spectral and fluorescence studies showed no indication of global conformational change of P450IA1 even with up to 8.8 mol lysine residues modified per mole P450IA1. These data suggest that at least three lysine residues in P450IA1 may be involved in the interaction with reductase. Identification of lysine residues in P450IA1 possibly involved in this interaction was carried out by [14C]acetic anhydride modification, trypsin digestion, HPLC separation, and amino acid sequencing. The lysine residue candidates identified in this manner were K97, K271, K279, and K407.

Mouse and human retinoic acid receptor beta 2 promoters: sequence comparison and localization of retinoic acid responsiveness

The retinoic acid receptor beta (RAR beta) gene is a member of the family of retinoic acid/thyroid hormone receptor genes, encoding retinoic acid-inducible transcription factors. To study regulation of the RAR beta gene, genomic clones containing the mouse and human retinoic acid receptor beta 2 (RAR beta 2) promoters were isolated and approximately 1.5 kb of upstream and downstream sequences relative to the transcriptional start site were completely sequenced. Both the mouse and human RAR beta 2 promoters are highly homologous around the transcription initiation site, with perfect conservation of the TATA box and retinoic acid responsive element (RARE). Promoter activation studies in P19 EC cells show, that the RARE in both the human and mouse promoters confers RA-responsiveness to the RAR beta 2 promoter. However, sequences located immediately upstream of the RARE also confer RA-inducibility to both the mouse and human RAR beta 2 gene promoters. This region contains conserved consensus sequences for a TPA-responsive element (TRE) and cAMP-responsive element (CRE), suggesting that in addition to regulation by RA receptors other transcription factors regulate RAR beta 2 expression in EC cells. Furthermore, the availability of the mouse RAR beta 2 promoter should facilitate studies for transgene expression and gene targeting experiments in embryonic stem cells.

Characteristics of embryonic stem cell differentiation: a comparison with two embryonal carcinoma cell lines

Embryonic stem (ES) cells isolated from late blastocysts can now be maintained in culture in an undifferentiated state provided they are grown in the presence of a specific differentiation inhibitor, known variously as leukaemia inhibiting factor (LIF) or differentiation inhibiting activity (DIA), found at high concentrations in medium conditioned by Buffalo rat liver (BRL) cells. ES cells acquired a differentiated phenotype in monolayer, either when in the absence of LIF/DIA or in the presence of retinoic acid (RA). We have now characterized this bipotential differentiation of ES cells in terms of a series of extracellular matrix and cell surface proteins as well as cytokeratin expression, and compared it with the changes observed during the differentiation of two embryonal carcinoma (EC) cell lines, P19 and F9. ES cells exposed to RA in the presence of LIF/DIA largely resembled F9 EC + RA after 5 days, while ES cells deprived of LIF/DIA formed a culture with mixed phenotype resembling P19 EC + RA. This study therefore establishes the predominantly parietal endoderm-like phenotype of cells derived from ES by RA induction, and suggests that a mixed population of endoderm- and ill-defined mesoderm-like cells are formed after removal of specific inhibitor(s) of differentiation.

Photon correlation spectroscopy of the polarization signal from single muscle fibres

Measurements of crossbridge dynamics have been obtained from the spectrum of diffracted light derived from single, skinned fibres of skeletal muscle. This technique combines optical ellipsometry with photon correlation spectroscopy of the intrinsic reporters from the muscle cell. The difference in the intensities of the two linearly polarized electric field components of diffracted light is autocorrelated in time, and the dynamics of optical anisotropy from the contributing units of the sarcomere are measured. In focusing on the fast-time dynamics, we detected two principal features: a rapidly relaxing temporal signal with a relaxation time of approximately 5 microseconds, and an oscillatory component which transforms into a broad but spectrally defined signal centred at around 370 kHz. Experiments were conducted to measure changes of these two signals upon relax-rigor transition and alpha-chymotrypsin degradation. These studies strongly suggest that the relaxational component of the signal is primarily due to myosin crossbridge motion; the 370 kHz spectral signal has as its likely source the myosin thick filament.

Polarization states of diffracted light. Changes accompanying fiber activation

Measurement of the state of optical polarization of light diffracted from single, skinned and intact fibers of anterior tibialis muscle from Rana pipiens revealed a dependence upon rigor, activation, and sarcomere length (SL) change. Changes in total birefringence, delta nT, and differential field ratio value, rT, were determined. In a relaxed, skinned fiber the total birefringence value, delta nT, decreases as sarcomere length is increased from 2.1 microns to approximately 2.8-3.0 microns. From there it increases significantly to a value of approximately 1.8 x 10(-3) at a sarcomere length of 3.6 microns. The differential field ratio, rT, also shows a biphasic response to increasing sarcomere length, first exhibiting a rapid decrease over shorter SL and leveling out after the SL is beyond 3.0 microns. In comparison, relaxed intact fibers change substantially less upon sarcomere length change, showing little change in birefringence and a small bi-phasic change in rT. Skinned fibers were activated using a solution that has the same ionic strength as the relaxing solution and allows repeatable, and sustained activation. A decrease in both delta nT and rT was observed upon fiber activation. The decrease in delta nT and rT was slightly larger at shorter sarcomere lengths than at longer lengths. Relaxed fibers placed in rigor showed changes in delta nT and rT similar to those observed in activated fibers. These results are consistent with the hypothesis that, after activation, a significant portion of the thick filament cross-bridges rotate towards the actin filament resulting in redistribution of the interfilament mass content. They are also consistent with an average orientation of crossbridges in the overlap region different from that in the nonoverlap region.

[The role of medial medulla in the depressive responses in pulmonary and carotid arteries to injection of acetylcholine at fourth ventricle]

The role of medial medulla in the depressive responses in pulmonary and carotid arteries to injection of acetylcholine (ACh) at the fourth ventricle was studied by means of electrolytic destruction and microinjection of drugs at the relevant brain areas. It was found that (1) electrolytic destruction of medial medulla significantly diminished the depressive responses to ACh in pulmonary and carotid arteries; (2) destruction of nucleus tractus solitarius (NTS) at the level of the medullary obex did not affect the depressive responses in both arteries; obex did not affect the depressive responses in both arteries; (3) microinjection of 5-hydroxytryptamine (5-HT) blockers, cyproheptadine and 2-bromolysergic acid diethylamide (BOL), into the fourth ventricle or medial medulla could lessen the depressive responses to ACh in pulmonary and carotid arteries; (4) microinjection of naloxone in the same way could partially abolish the depressive responses. It is thus assumed that the ACh-induced depressive responses in pulmonary and carotid arteries are associated with the structural integrity of the medial medulla but not related to the central projection area of the buffer nerves. Therefore, the depressive responses in pulmonary and carotid arteries initiated by injection of ACh at the fourth ventrical are mediated by activating the 5-HT and endorphin systems of the medial medulla which in turn inhibits the tonic activities of the sympathetic preganglionic neurons in the spinal cord.

Lymphocyte subpopulation with low membrane potential in the blood of cyclosporin- and prednisone-treated patients: in vivo selectivity for T4 subset

Previous work on the mode of action of CsA revealed that this drug shifts the membrane potential of human periferal blood lymphocytes in vitro. Recently we have analyzed lymphocytes of cyclosporin-treated transplant patients. Membrane potential analysis with the DIOC6(3) fluorescence dye indicates that all the studied patients have a subpopulation of lymphocytes with low membrane potential and that this population is made up predominently of OKT4+ cells. However there is no correlation between the clinical events and the percentage distribution of lymphocyte subpopulations as defined by the membrane potential and the T4/T8 ratio of the total lymphocyte population.

Effects of calcium channel blockers on in vivo cellular immunity in mice

In vitro studies have shown that calcium channel blockers (CCB) inhibit lectin-induced lymphocyte proliferation. However, no in vivo effects have been documented yet. In this study we evaluated the effects of CCB on in vivo cellular immunity by using contact sensitivity to oxazolone in mice. From 15 to 30 twelve-week-old female C3H mice were randomized into: 0.9 NS (sham), ethanol, CsA, dexamethasone (DXM), verapamil, diltiazem, and nifedipine groups. These study agents were given daily from day 1 to day 9 subcutaneously to the shaved abdominal wall. The mice were sensitized with oxazolone to the abdominal wall on day 2 and challenged with oxazolone on the right ear on day 8. Delayed-type hypersensitivity was measured on day 10 and defined as the difference in thickness between the right (challenged) and left (control) ear of each mouse. The mean DTH of each study group was compared with that of the sham, and the statistical significance was determined by a Student's t test. The percentage of change in DTH from the sham was also calculated as: (mean DTH of study drug group-mean DTH of sham group)/mean DTH of sham group x 100%. A negative value meant a suppressive effect on DTH; a positive value, an enhancing one. The CsA, DXM, and nifedipine all had significant suppressive effects on DTH. Verapamil had a significant enhancing effect. Ethanol and diltiazem had no significant effect. More studies employing other antigens with several other cell-mediated response measurements along with DTH quantification should be done in order to determine the specificity of the immunosuppressive effect of CCB as well as the potential of any calcium antagonist as an adjuvant suppressive agent.

Incidence and morbidity of cytomegalovirus disease associated with a seronegative recipient receiving seropositive donor-specific transfusion and living-related donor transplantation. A multicenter evaluation

This retrospective study was conducted to identify the frequency of cytomegalovirus (CMV) disease in seronegative recipients of donor-specific transfusion (DST) and living-related donor (LRD) kidneys from seropositive donors. A total of 151 LRD transplants (TX) were performed at six transplant centers over a 3-year period. A total of 33 patients were identified as having been seronegative (pre-TX) for CMV, yet they had DST and a TX from a seropositive LRD. Of these patients, 12 (36.4%) seroconverted within the first 6 months post-TX and developed clinical CMV disease. Additional patients seroconverted, but did not have evidence of clinical disease and were not tested further. All TX centers, with the exception of one, had seronegative patients that became ill after receiving a seropositive DST/LRD TX. Six patients manifested their disease as a febrile illness with leukopenia and liver enzyme elevations, four had pneumonitis, and two developed CMV ulcerations of the colon (one of whom died from resultant sepsis). Of the 36 seronegative patients who received seronegative DST/LRD TX none became ill with CMV disease. Of the 72 seropositive patients who received DST/LRD TX, only 2 (2.8%) developed CMV illness (one, seropositive into seropositive, the other, seronegative into seropositive). Of the 33 seronegative patients receiving seropositive DST/LRD TX, 17 received antilymphocyte preparations (ALP), and 8 of these became ill (47.1%). Of 16 patients not receiving ALP, 5 (31.3%) developed clinical CMV illness. Of the 33 patients who were identified as having been seronegative for CMV yet received seropositive DST/LRD TX, the 12 who did develop CMV illness had two graft losses, one death, and a serum creatinine for the remaining 9 patients of 2.3 +/- 1.6 at last follow-up. The remaining 21 patients who developed no illness had a serum creatinine of 1.3 +/- 0.6 with no graft losses at the last follow-up. This evidence suggests that a prospective TX recipient who is seronegative for CMV who receives DST/LRD TX from a seropositive family member has a significant risk for developing morbidity related to clinical CMV illness.