Changes in GABAA receptor function and cross-tolerance to ethanol in diazepam-dependent rats

Changes in gamma-aminobutyric acidA (GABAA) receptor function and their relation to cross-tolerance to ethanol (EtOH) were studied in diazepam (DZP)-dependent rats. Physical dependence on DZP was induced in male Fischer rats by using the drug-admixed food method. The 38Cl- influx into cerebral cortical synaptoneurosomes induced by 10 microM GABA in DZP-withdrawn rats was significantly increased, compared with control and DZP-tolerant rats. Although enhancement of GABA-dependent 38Cl- influx by the addition of EtOH and flunitrazepam (FZ) was recognized in the control, there was no such effect of EtOH or FZ in the DZP-tolerant animals. On the other hand, GABA-dependent 38Cl- influx was enhanced by FZ in the withdrawn group. The addition of picrotoxin and bicuculline inhibited GABA-dependent 38Cl- influx in each group. The stimulatory effect of FZ on GABA-dependent 38Cl- influx was inhibited by the addition of Ro 15-1788 in the control group. However, such an inhibitory effect was not observed in the withdrawn group. The antagonistic effect of Ro 15-4513 on EtOH stimulation of GABA-dependent 38Cl- influx observed in the control was not recognized in the withdrawn group. In a [3H]FZ assay of binding to benzodiazepine (BZ) receptors, Bmax values were significantly increased in DZP-withdrawn animals, but decreased in the DZP-tolerant group, compared with the control. When [3H]muscimol binding was examined, the Kd of high-affinity sites of the GABAA receptor in withdrawn rats was significantly lower than in the control. In low-affinity binding sites, the values of Kd and Bmax were significantly decreased, compared with those in the control. The present study indicates that GABAergic transmission involving the regulation of GABA-dependent chloride channels is altered in DZP-dependent rats. Alterations of the GABAA/BZ/chloride channel complex function may be related to the cross-tolerance between BZ and EtOH.

Angiographic assessment of the stretch-recoil-gain relation after balloon coarctation angioplasty and its relation to late restenosis

The effects of stretch and immediate recoil after balloon angioplasty were evaluated in 21 patients with coarctation of the aorta who underwent balloon coarctation angioplasty. A total of 28 procedures were performed in these patients, who ranged in age from 1 month to 17 years with a mean of 4.3 years. The systolic pressure gradient and coarcted diameter changed significantly from 42 +/- 22 to 14 +/- 9 mmHg (P < 0.0001) and from 4.0 +/- 1.7 to 6.1 +/- 2.0 mm (P < 0.001), respectively. Immediate recoil was responsible for the loss of 33% of the potentially achievable coarcted dimension. Recoil was determined mainly by the degree of arterial stretch. Gain increased exponentially with an increase in stretch. There was a narrow range of % stretch (60-80%) within which an effective diameter gain could be obtained. Both gain and stretch were the best predictors for late restenosis: patients with a larger immediate gain and stretch developed more restenosis. These results suggest that the stretch-recoil-gain relationship may be clinically important for evaluating the best predictor of late restenosis after balloon coarctation angioplasty.

Targeting chemotherapy for malignant brain tumor using thermosensitive liposome and localized hyperthermia

Thermosensitive liposomes are microscopic vesicles that can contain drugs and release them effectively in response to hyperthermia. To deliver an antitumor drug specifically to brain tumor, the authors used thermosensitive liposomes containing cis-diamminedichloroplatinum (CDDP) in conjunction with localized brain heating. The authors then investigated the antitumor effect on rat malignant glioma. Rous sarcoma virus-induced malignant glioma cells were transplanted into the brains of Fisher rats. Ten days after tumor inoculation, the rats were assigned to one of six treatment groups: control, free CDDP, hyperthermia, free CDDP + hyperthermia, liposomes containing CDDP (CDDP-liposome), and CDDP-liposome + hyperthermia. Liposomes containing CDDP or free CDDP were injected via the tail vein. Brain tumor heating was administered by means of a radiofrequency antenna designed at our institute. The rats treated with CDDP-liposome + hyperthermia had the longest survival time and the tumor CDDP level of this group was the highest when compared to the other groups. Histopathological examination showed that tumor cells were necrotized but surrounding normal brain tissue remained undamaged. On the basis of these findings we suggest that the combination of thermosensitive liposome and localized hyperthermia may better focus antitumor drugs to the tumor, providing a significantly greater antitumor effect.

Molecular analysis of a series of alleles in humans with reduced activity at the triosephosphate isomerase locus

Individuals with 50% of expected triosephosphate isomerase (TPI) enzyme activity have been previously identified in families during the screening of approximately 2,000 newborn children for quantitative variation in activity of 12 erythrocyte enzymes. The frequency of the trait was 9/1,713 individuals in the Caucasian population and 7/168 individuals among the African-American population studied. Genetic transmission of the trait was confirmed in all families. The frequency of the presumptive deficiency allele(s) at the TPI locus was greater than expected, given the reported incidence of clinical TPI deficiency. We report the molecular characterization of the variant alleles from seven African-American and three Caucasian individuals in this group of unrelated individuals. Three amino acid substitutions--a Gly-->Ala substitution at residue 72, a Val-->Met at residue 154, and a previously described Glu-->Asp substitution at residue 104--were identified in the Caucasian individuals. The substitutions occur at residues that are not directly involved in the active site but are highly conserved through evolutionary time, suggesting important roles for these residues in maintenance of subunit structure and conformation. The variant allele in the seven African-American individuals had nucleotide changes at positions -8 and -5 (5' of) from the transcription-initiation site. In three of these individuals, an additional T-->G substitution was detected in a TATA box-like sequence located 24 nucleotides 5' of the transcription-initiation site and on the same chromosome as the -5/-8 substitutions. Thus, molecular alterations at the TPI locus were detected in 10 unrelated individuals in whom segregation of a phenotype of reduced TPI activity previously had been identified.

A reproducible assay of polymerase chain reaction to detect trinucleotide repeat expansion of Huntington's disease and senile chorea

A simple and reproducible method of polymerase chain reaction (PCR) assay was established to detect trinucleotide repeat expansion for Huntington's disease (HD) using a new DNA polymerase and buffer system. The system consists of an extremely heat stable DNA polymerase (Pfu), and a buffer supplemented with ammonium sulfate and dimethyl sulfoxide. Previous methods to amplify expanded alleles for HD have been very complex in PCR conditions, but the reproducibility was sometimes very low because of repetitive sequences around the primer sequences. With the present method, strong bands for the disease alleles were reproducibly visible in a conventional agarose gel stained with ethidium bromide without using isotopes. Three cases with sporadic HD and a case with senile chorea showed expanded alleles for HD with smaller sizes of the expansion than cases with typical HD. These results showed that the present method provides a simple and reproducible way to detect HD allele, and some cases with sporadic HD and senile chorea had expanded HD alleles.

Elevated tyrosine hydroxylase mRNA levels in medulla oblongata of spontaneously hypertensive rats

The present study has investigated the expression of tyrosine hydroxylase (TH) mRNA and its activity in medulla oblongata of spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). The TH mRNA levels were determined by Northern blot and dot blot analyses. The TH activity and the expression of TH mRNA in medulla oblongata of SHR were significantly higher than those of WKY. These results suggest that the hypertension of SHR may be related to the high activity of TH due to the high level of TH mRNA which increases norepinephrine levels in the medulla oblongata.

Expression of exogenous protein and analysis of morphogenesis in the developing chicken heart using an adenoviral vector

OBJECTIVES

Recombinant retroviral vectors have been shown to be useful tools for marking cells so as to follow their fates during development. The aim of this study was to determine the utility and advantages of an adenoviral vector as a tool to study the heart as it develops from a simple tube into a complex four-chambered organ.

METHODS

Replication-defective adenovirus (10(7) pfu) expressing beta-galactosidase (beta-gal) under the control of the RSV-LTR was applied to the external surface of embryonic stage 13-21 chick hearts in ovo. Embryos were incubated for up to an additional 96 h. Hearts were harvested at 12-24 h intervals and (1) whole-mount-stained for beta-gal and sectioned, (2) examined by electron microscopy and (3) homogenized and beta-gal activity measured with a luminescent assay.

RESULTS

beta-gal expression peaked at 48 h, when a significant percentage of the myocytes in the atrial and ventricular walls expressed the protein, and it comprised 0.5% of total heart protein. Significant levels were still expressed at 96 h. When applied to early-stage (13-16) embryos, expression occurred predominantly in cardiomyocytes. beta-gal marking of cells enabled us to identify the following morphogenic patterns: (1) cells of the conus region compact into the bulbis cordis; (2) by applying the virus at later stages, e.g. 21-22, it was evident that the epicardium invests the heart, after stage 17, in a dorsal to ventral and caudal to rostral direction; (3) at lower titers (10(5) pfu), the virus serves as a clonal marker through several cell divisions, with an estimated cell doubling time of 24 h.

CONCLUSIONS

Application of an adenoviral vector to early-stage embryonic chick heart results in substantial expression of exogenous protein in a significant percentage of cardiomyocytes without grossly affecting heart development. Adenoviral vectors are useful for following the fate of cells as the heart develops from a simple tube into a complex four-chambered organ and hold promise for enabling the expression of exogenous proteins which might alter cell behavior.

Cellular induction mechanism of CD8+ suppressor T cells by DMBA and TPA: formation of CD4+ suppressor-inducer T cells

We investigated the cellular induction mechanism of antigen-nonspecific CD8+ T suppressor cells which suppressed delayed-type hypersensitivity to sheep red blood cells, by treating BALB/c mice with 7,12-dimethylbenz[a]anthracene (DMBA), a tumor initiator, and 12-O-tetradecanoylphorbol 13-acetate (TPA), a tumor promoter. Macrophages were activated by painting with 400 nmol of DMBA on mice. And the macrophages plus TPA induced CD4+ T suppressor inducer cells in the mice spleens. These cells were efficient at inducing CD8+ T suppressor-effector cells. When 8 nmol of TPA was painted daily on mice for 3 days following the treatment with 400 nmol of DMBA, or when spleen cells from mice pretreated with 400 nmol of DMBA were cultured in 32 nmol/5 ml of TPA for 3 days, inducer cells were formed in the spleen. Both T suppressor-inducer cells and macrophages from mice treated with DMBA were shown to act with the formation of soluble factors, which may be different from IL-10.

Deletion mapping on chromosome 1p in well-differentiated gastric cancer

To define the region on the short arm of chromosome 1 that is thought to include one or more tumour-suppressor genes for gastric cancers, we carried out loss of heterozygosity (LOH) studies in 26 gastric adenocarcinomas, using three restriction fragment length polymorphism (RFLP) markers and nine microsatellite markers. All tumours were informative with at least one locus; three revealed replication errors (RERs) at multiple microsatellite loci, and interstitial or telomeric allelic deletions were observed in 12 cases. Deletion mapping of these tumours defined a commonly deleted region between two loci, D1S201 and D1S197, that are 13 cM apart. As two loci within the commonly deleted region, D1S57 (pYNZ2) and D1S62 (pTHI54), were mapped respectively to 1p35 and 1p34.3 by fluorescence in situ hybridisation, we conclude that a locus likely to contain a tumour-suppressor gene for gastric cancer is located within a 13 cM region encompassing two chromosomal bands.

Antitumour activity of cis-diamminedichloroplatinum (II) against human tumour xenografts depends on its area under the curve in nude mice

A pharmacodynamic analysis of cis-diamminedichloroplatinum(II) (DDP) was conducted using two human gastric cancer xenografts, SC-1-NU and MKN-45, and one human breast cancer xenograft, MX-1, grown serially in BALB/c nu/nu mice. DDP was administered intraperitoneally (i.p.) at a total dose of 5, 10, or 20 mg/kg in a schedule of q7d x 3 or (qd x 5) x 3. DDP was also administered i.p. to BALB/c +/? mice, whose plasma was used for the assay of total and free platinum by the atomic absorption method. A total dose of 20 mg/kg DDP seemed to be the maximum tolerated dose that was effective on MX-1 and SC-1-NU. When the totally administered doses were equivalent, the antitumor effects of the q7d x 3 and (qd x 5) x 3 schedules were similar to each other. The antitumor activity of DDP against MKN-45 was dependent on the total administered dose as well as the area under the curve of free and total platinum in the plasma. Side effects were significantly reduced using a schedule of (qd x 5) x 3 in terms of body and spleen weight loss when a total of 10 or 20 mg of DDP per kg was administered. These results suggest that DDP would be useful when administered using a daily schedule for obtaining the same antitumor activity as that of bolus injection but with reduced adverse effects.

Impairment of suckling response, trigeminal neuronal pattern formation, and hippocampal LTD in NMDA receptor epsilon 2 subunit mutant mice

Multiple epsilon subunits are major determinants of the NMDA receptor channel diversity. Based on their functional properties in vitro and distributions, we have proposed that the epsilon 1 and epsilon 2 subunits play a role in synaptic plasticity. To investigate the physiological significance of the NMDA receptor channel diversity, we generated mutant mice defective in the epsilon 2 subunit. These mice showed no suckling response and died shortly after birth but could survive by hand feeding. The mutation hindered the formation of the whisker-related neuronal barrelette structure and the clustering of primary sensory afferent terminals in the brainstem trigeminal nucleus. In the hippocampus of the mutant mice, synaptic NMDA responses and longterm depression were abolished. These results suggest that the epsilon 2 subunit plays an essential role in both neuronal pattern formation and synaptic plasticity.

Intracellular generation of amyloid beta-protein from amyloid beta-protein precursor fragment by direct cleavage with beta- and gamma-secretase

Two amyloid beta protein precursor (beta APP) fragments involving Met and 103 amino acids of C-terminus of beta APP (delta NOR-beta) and its KM-NL substitution (delta NL-beta) were expressed in COS-7 cells to clarify the proteolytic cleavages to generate amyloid beta protein (A beta). The 4.5-kD protein, A beta with additional N-terminal amino acids, and 4-kD A beta were directly produced and released from 12.5-kD expression proteins without any production of 11.4-kD C-terminal fragment starting at N-terminus of A beta and 3-kD "p3" A beta derivative. Intracellular 4-kD A beta was also detected. The substitution of KM-NL of beta APP found in Swedish familial Alzheimer's disease (AD) promoted the production of intracellular A beta and its release with no increase in level of 11.4-kD C-terminal fragment. These results suggested the presence of a distinct pathway in which A beta is directly cleaved at both N- and C-termini from beta APP fragment intracellularly to release A beta. Since KM-NL substitution enhanced intracellular A beta generation, this pathway may be associated with amyloidogenesis in AD.

The modulating effect of interferon alpha-2a on the antitumor activity of UFT against a human gastric carcinoma xenograft, SC-1-NU, in nude mice

The modulating effect of recombinant human interferon alpha-2a (IFN) on the antitumor activity of UFT, a mixed compound of tegafur and uracil at a molar ratio of 1:4, was investigated against SC-1-NU, a human gastric cancer xenograft serially transplanted in nude mice. IFN was administered subcutaneously at a dose of 60,000 IU/mouse daily for 14 days, and UFT was given at a dose of 15 mg/kg as tegafur daily, except on Sundays, for 3 weeks. The agents were administered either alone or simultaneously. Synergistic antitumor activity on SC-1-NU was produced by the combination of IFN and UFT without any increment of side effects, and the combination therapy also increased intratumoral thymidylate synthetase (TS) inhibition and the amount of 5-fluorouracil (5-FU) in the intratumoral RNA. Thus, IFN seems to modulate the antitumor activity of UFT against SC-1-NU through an inhibition of DNA synthesis and RNA distortion, and therefore this combination could be useful for clinical application.

[Medial medullary infarction following neck manipulation]

Reported is a case of a 39-year-old man with medial medullary infarction following chiropractic neck manipulation. Neurologically, he showed right hemiparesis sparing the face, right deep sensory impairment and tongue deviation to the left in five hours after neck manipulation. A cranial MRI revealed an ischemic lesion in the left medial portion of the medulla oblongata. Cerebral angiography demonstrated no apparent organic lesion of the right vertebral artery (VA), but showed hypoplasia of the left VA. We suspect that the left medial medullary infarction occurred because of the reduced VA blood flow following the contralateral VA compression, in addition to the ipsilateral VA hypoplasia. This case is the first one reported in which medial medullary infarction was possibly induced by neck manipulation.

[Flameless atomic absorption spectrometry for analysis of trace elements in biological materials]

The variation factors of data using atomic absorption method are considered as follows: 1. Sampling 2. Contamination of glassware 3. Damaged cuvettes 4. Chemical interference by coexisting elements. Those problems of the variation factor are solved by checking and replacement of sample nozzle, glassware, and cuvettes. The chemical interferences are also removed by using platform and exhausting gas strongly inside of cuvettes, and keeping constant temperature of cuvettes when ashed. In addition to the above condition, the adjustment of background of choosing apparatus provide highly sensitive, accurate measurement without using standard adding method.

Effects of recombinant human granulocyte colony-stimulating factor on the growth potential of two murine myeloid leukemias

We investigated the in vitro and in vivo effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on the proliferation of two murine leukemic cell lines. The rhG-CSF stimulated leukemic colony formation of the promyelocytic leukemic cell line L-8801 in methylcellulose culture and increased the number of L-8801 cells in liquid culture. However, rhG-CSF treatment prolonged the median survival period of mice implanted with L-8801 cells and the emergence of the leukemic blast cells in peripheral blood. Meanwhile, rhG-CSF had no influence on that of the megakaryoblastic leukemic cells L-8057 and failed to prolong the median survival period of L-8057 leukemic mice. Receptor binding analysis revealed that L-8801 cells expressed a G-CSF receptor (Kd=125 pM, 479 binding sites/cell) and L-8057 cells had no G-CSF receptors. Then, we examined the growth potential of these cells. The median survival period was longer for mice implanted with L-8801 cells cultured with rhG-CSF for 72 h in vitro than for cells grown without rhG-CSF. Furthermore, the median survival period of mice implanted with spleen cells from L-8801 leukemic mice treated with rhG-CSF was prolonged compared with those from leukemic mice without rhG-CSF. In contrast, there was no effect of rhG-CSF on the growth potential of the spleen from L-8057 leukemic mice. The results of our present study demonstrate that rhG-CSF reduced the growth of L-8801 leukemic cells in vitro and in vivo mediated through G-CSF receptors, thereby suppressing the development of leukemia.

Drug delivery to the brain using thermosensitive liposome and local hyperthermia

We investigated the possibilities of drug delivery to the brain using thermosensitive liposomes and hyperthermia. Thermosensitive liposomes are small vesicles containing some drugs, which are designed to release the drugs in response to hyperthermia. The first experiment consisted of four groups: (1) received free Cisplatin: cis-diamminedichloroplatinum (CDDP); (2) received free CDDP and above 41 degrees C local brain heating for 30 min; (3) received liposomes containing CDDP (CDDP-liposome); and (4) received CDDP-liposome and above 41 degrees C local brain heating for 30 min. Brain CDDP levels were significantly higher in (4), while those on the other groups were undetectable. In the second experiment, we studied the distribution of Evans blue (Eb) in the artificially heated region of mongrel dogs' brain. One group received free Eb and the other group received liposomes containing Eb (Eb-liposome). While the extravasation of free Eb was localized in regions heated > 44 degrees C, that of Eb-liposome was extended up to the regions heated at 41 degrees C. We concluded that the use of thermosensitive liposomes and hyperthermia not only contributes to the brain tumour killing as direct thermal killing does but also helps to increase the concentration of chemotherapeutic drugs into the tumour invaded zones with mild local hyperthermia of 41 degrees C.

Protective action of ulinastatin against cisplatin nephrotoxicity in mice and its effect on the lysosomal fragility

The development of azotemia after cisplatin injection in mice was inhibited by ulinastatin treatment in a dose-dependent manner. Reduction in creatinine clearance and elevation in fractional excretion of sodium in mice receiving cisplatin was ameliorated by ulinastatin administration. Epithelial necrosis and hyaline cast formation in the proximal tubule were also suppressed. Ulinastatin showed no influence on the kidney platinum level after cisplatin injection. In LLC-PK1 cells, addition of ulinastatin to the incubation medium markedly reduced the release of N-acetyl-beta-D-glucosaminidase, on of the lysosomal enzymes, during hypotonic treatment only when cells were damaged with cisplatin. On the other hand, ulinastatin showed no effect on the elevation of malondialdehyde concentration in the murine kidney cortical slices after the treatment with cisplatin. These results indicate that ulinastatin has a protective effect against cisplatin nephrotoxicity, and its prevention of the increase in lysosomal fragility is a probable mechanism involved in the renal protection.

Protective effect of human ulinastatin against gentamicin-induced acute renal failure in rats

We investigated the protective effect of human ulinastatin against gentamicin-induced acute renal failure in rats. Gentamicin sulfate was subcutaneously injected at a dose of 200 mg/kg for 5 consecutive days. After 3 days administration of gentamicin, a slight decrease in renal function was observed, as well as granulovascular degeneration in the proximal tubular cells as a change in the renal histology. After 5 days administration of gentamicin, a remarkable increase in plasma concentration of creatinine (from 0.27 +/- 0.02 to 1.17 +/- 0.18 mg/dL) and urea nitrogen (from 17.8 +/- 0.6 to 48.8 +/- 5.1 mg/dL) and a significant decrease in creatinine clearance (from 0.64 +/- 0.08 to 0.20 +/- 0.03 mL.100 g-1.min-1) were observed. In addition, an apparent increase in urinary excretion of N-acetyl-beta-D-glucosaminidase and albumin was detected. In the renal histology, proximal tubular necrosis and desquamation of the epithelial cells in the cortex were observed. Furthermore, hyaline cast formation was frequently observed in the outer stripe of the outer medulla. Ulinastatin at doses of 100,000 or 300,000 U/kg was coadministered intraperitoneally just after each gentamicin injection. Ulinastatin treatment showed a dose-dependent suppression of gentamicin-induced biochemical alterations and histological changes. After 5 days treatment with 300,000 U.kg-1.day-1 of ulinastatin, the magnitude of gentamicin-induced changes in renal function was significantly lessened, by 45-80%. The score for proximal tubular injuries and the rate of hyaline cast formation were also significantly lower in the same group of animals than those in the group treated with gentamicin alone. In the in vitro study, ulinastatin at 10-300 U/mL showed a concentration-dependent suppression on the fragility of the lysosomal membrane isolated from rat kidney cortex during hypotonic treatment. These results indicate that human ulinastatin has a prominent protective effect on gentamicin-induced acute renal failure in rats, and the lysosomal membrane stabilizing effect is possibly involved as a mechanism of this action.

DNA adduct formation, cell proliferation and aberrant crypt focus formation induced by PhIP in male and female rat colon with relevance to carcinogenesis

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) induces colon tumors in male, but not female, F344 rats. We investigated the mechanisms leading to this difference by measuring the level of PhIP-DNA adducts, the enhancement of cell proliferation and aberrant crypt focus (ACF) formation in colon mucosa. PhIP was administered in the diet at a level of 0.04% to both male and female F344 rats for 1-8 weeks. The level of DNA adducts in the colon mucosa was measured using the 32P-postlabeling method. Four major PhIP-DNA adducts were detected in fairly constant proportions in all the animals examined. The level of PhIP-DNA adducts in male and female rats was the same, indicating no direct correlation between adduct levels and carcinogenesis. Labeling indices (LIs) were determined by measuring BrdU incorporation in rats after feeding with a PhIP diet for 4, 8 and 12 weeks. After 8 weeks administration the LI had increased 1.5-fold in the colon of the male rats, but no increase was observed in the female rats. ACF formation was examined after feeding with a PhIP diet for 14 weeks. The number of aberrant crypt foci was 6.6 +/- 1.5 per rat in males and 1.9 +/- 0.5 per rat in females. Thus differences in colon tumor development in male and female rats takes place at an early stage(s). Our results suggest that, in addition to DNA adduct formation, enhanced proliferation contributes to the formation of ACFs, which are premalignant lesions of the colon.