Microscopic analysis of enzyme activity, mitochondrial distribution and hydrogen peroxide in two-cell rat embryos

A developmental block is induced by phosphate in rat embryos at the late two-cell stage. The present study was designed to examine the energy metabolism of rat two-cell blocked and non-blocked embryos. Enzyme activity was measured in individual embryos by histochemical techniques. The activities of malate dehydrogenase, isocitrate dehydrogenase, lactate dehydrogenase, pyruvate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, glutamate dehydrogenase, glucose-6-phosphate dehydrogenase, glucose-6-phosphatase, and phosphorylase did not differ among non-blocked and blocked embryos. However, the activity of succinate dehydrogenase was significantly decreased in blocked embryos compared with non-blocked embryos. In blocked embryos, cytochrome oxidase activity was distributed homogeneously, but was located at the perinuclear region in non-blocked embryos. Active mitochondrial organization was visualized using the fluorescent probe rhodamine 123 and laser scanning confocal microscopy. In both non-blocked and blocked embryos, mitochondria were distributed homogeneously. The concentration of H2O2 measured fluorometrically in embryos cultured without phosphate did not change significantly during the culture period, but decreased in embryos cultured with phosphate. The timing corresponded to the occurrence of the two-cell block. In summary, these results suggest that the developmental block in rat two-cell embryos is induced by disturbance of mitochondrial energy metabolism.

Distribution and expression of mRNAs for the proto-oncogenes c-fos and c-jun in bone cells in vivo

In this study we assessed the expression and localization of the proto-oncogenes c-fos and c-jun in normal bone so as to gain more insight into the role of these proto-oncogenes in bone tissue. Femurs of 4-week-old rats were examined by non-radioactive in situ hybridization. cDNA probes for c-fos- and c-jun-labeled digoxygenin were produced by Polymerase Chain Reaction (PCR). C-fos and c-jun exhibited similar distribution in growth plate and bone tissue. Expression of c-fos and c-jun mRNAs in growth plate was observed in the proliferative zone and partly in the upper layer of the hypertrophic zone. In spongy bone, high expression of c-fos and c-jun mRNAs was observed in the osteoblast cytoplasm. However, there was little expression in bone lining cells. In the bony trabeculae, slight expression of c-fos and c-jun was observed in the premature osteocytes situated close to the bone surface, but no expression was detected in osteocytes that possessed relatively large lacunae in the center of the trabeculae. C-fos and c-jun were also slightly expressed in osteoclasts. These data strongly suggest that c-fos and c-jun are involved in regulating chondrocyte proliferation as immediate early genes, and may also be involved in the gene expression of bone matrix proteins as transcription factor (AP-1) in vivo. In addition, the fact that strong expression was observed in osteoblasts but hardly any expression at all in bone lining cells seems to suggest that these genes are also involved in osteoblast activation.

Flt3/Flk-2 and c-Kit are not essential for the proliferation of B lymphoid progenitor cells in the bone marrow of the adult mouse

The receptor tyrosine kinase Flk-2/Flt3 was originally cloned from hematopoietic stem cell-enriched fetal liver and placenta and is believed by some investigators to play a role in the regulation of the hematopoietic stem cell. However, targeted disruption of the flt3 gene results in a specific deficiency in early B cell progenitors. Using an antagonistic monoclonal antibody developed against the extracellular domain of Flt3, we investigated the expression and function of the molecule on B lymphoid lineage cells in the bone marrow (BM) of adult mice. Approximately 10% of B220+ cells in the BM expressed Flt3 on the cell surface, and most of the cells belonged to a pro-B cell fraction when judged by an expression pattern of CD43, heat-stable antigen, and BP-1. However, B lymphoid precursor cells that are clonable in vitro could not be enriched in the B220+/Flt3+ cell fraction sorted by flow cytometry. Furthermore, proliferation of B lymphoid precursor cells in the adult BM was not blocked by administration of the antagonistic monoclonal antibodies against Flt3 and c-Kit, suggesting that signalings mediated by Flt3 and c-Kit receptors are not essential for the proliferation of B cell progenitors in adult mouse BM.

[Value of transtracheobronchial ultrasonography in the assessment of mediastinal lymphadenopathy in patients with lung cancer]

In patients with lung cancer, decisions regarding treatment can depend on the diagnosis of hilar and mediastinal nodal involvement. We prospectively compared the diagnostic value of computed tomography (CT) with that of transtracheobronchial ultrasonography (TUS) in the evaluation of lymphadenopathy. Five patients with resectable lung cancer were studied. TUS was done with EU-M 20 or M 30 and lymph nodes located at #3, #4, #7, ipsilateral #10, and #11 were observed and measured. TUS findings, CT findings, and histological findings were evaluated and compared. The sizes of lymph nodes as measured by TUS were similar to or slightly smaller than their sizes as measured by CT. Hilar lymph nodes and lymph nodes located at right #4 were clearly observed with TUS, but were sometimes unclear with CT. Diagnosis of model involvement by TUS needs further study.

Peripheral blood lymphocytes from psoriatic patients are hyporesponsive to beta-streptococcal superantigens

The strong association of acute guttate psoriasis and streptococcal throat infection, together with the preferential use of T cells expressing a particular T-cell receptor, has suggested a role for bacterial superantigens in the pathogenesis of psoriasis. We examined the proliferative responses of peripheral blood lymphocytes (PBLs), obtained from patients with psoriasis and from healthy controls, to streptococcal superantigens, cytoplasmic membrane-associated protein (CAP) and secretion-type CAP (SCAP), isolated from group A, beta-haemolytic streptococci. PBLs from patients with psoriasis showed significantly less response to SCAP and CAP than those from healthy controls. Because there was no difference between psoriatic patients and controls in the proliferative response of PBLs to staphylococcal enterotoxin A or E (SEA, SEE) or the mitogen phytohaemagglutinin (PHA), these findings strongly suggest that the reduced reactivity to the streptococcal superantigens seems to reflect anergy of a population of PBLs to the superantigens. As the CAP used in the present study stimulates V beta 8 T cells selectively, we further examined the proliferation of V beta 8 T cells after such stimulation using flow cytometry. V beta 8 T cells obtained from three of four psoriatic patients failed to proliferate in the presence of CAP, whereas they proliferated vigorously in the presence of SEE, which activates V beta 8 T cells, confirming the specific hyporesponsiveness of PBLs from psoriatic patients to streptococcal superantigens. We then determined the effects of serum factors on the suppressed response of PBLs to the streptococcal superantigens with SCAP or CAP. It was partially restored when PBLs were cultured with sera obtained from healthy subjects, although the responses were still significantly lower than those of the healthy controls. In contrast, psoriatic sera markedly suppressed the proliferative response of PBLs from healthy controls to CAP or SCAP, but showed no suppression of the proliferative response of PBLs to SEA. Because these findings suggest the presence of specific inhibitory factors in psoriatic sera, we examined whether the inhibitory effect was caused by antisuperantigen antibody. However, no significant increase was detected in antibody titre to CAP in psoriatic sera, as has been noted in sera from patients with poststreptococcal glomerulonephritis. The present results show for the first time the hyporesponsiveness of PBLs to streptococcal superantigens and the presence of serum inhibitors that specifically inhibit T-cell response to the superantigens in psoriatic patients. These findings suggest a pathological role for streptococcal infections in the pathogenesis of psoriasis.

Effect of phosphate on the second cleavage division of the rat embryo

Development of the rat embryo is arrested at the 2-cell stage in vitro in the presence of inorganic phosphate (Pi). Rat embryos were affected by exposure to 1.19 mM KH2PO4 in modified hamster embryo culture medium-1 at the late 2-cell stage only. When exposure durations were 6 h, embryos whose exposure timings were prior to cleavage had a reduced rate of development to the blastocyst stage (2-8%) when compared with embryos with no exposure to Pi (97%, P < 0.05). When exposure durations were 18 h, all embryos were arrested at the 2- to 4-cell stage. These timings would correspond to the G2 to M phase of the second cell cycle. Maturation-promoting factor (MPF), which is regulated by a phosphorylation cascade, controls cell division, and its kinase activity is necessary in order for the cell to enter the M phase. However, the histone H1 kinase activity levels and the patterns of the state of phosphorylation of cdc2 were the same in blocked and non-blocked embryos. Because MPF was active in blocked embryos, the developmental block in rat 2-cell embryos caused by phosphate was not due to MPF activity or its phosphorylation cascade.

Effects of scatter and attenuation correction on quantitative assessment of regional cerebral blood flow with SPECT

Appropriate corrections for scatter and attenuation correction are prerequisites for quantitative SPECT studies. However, in most cerebral SPECT studies, uniform attenuation in the head is assumed, and scatter is usually neglected. This study evaluated the effect of attenuation correction and scatter correction on quantitative values and image contrast.

METHODS

Studies were performed in six normal volunteers (ages 22-26 yr) following intravenous 123I-IMP administration using a rotating, dual-head gamma camera. A transmission scan was acquired with a 99mTc rod source (74 MBq) placed at the focus of a symmetrical fanbeam collimator. Data were reconstructed using two attenuation coefficient (mu) maps: quantitative mu map from the transmission scan and a uniform mu map generated by edge detection of the reconstructed images. Narrow and broad beam mu values were used with and without scatter correction, respectively. Scatter was corrected with transmission-dependent convolution subtraction and triple-energy window techniques. Quantitative rCBF images were calculated by the previously validated IMP-autoradiographic technique, and they were compared with those obtained by (15)O-water and PET. SPECT and PET images were registered to MRI studies, and rCBF values were compared in 39 ROIs selected on MRI.

RESULTS

Clear differences were observed in rCBF images between the measured and constant mu maps in the lower slices due to the airways and in the higher slices due to increased skull attenuation. However, differences were < 5% in all cerebral tissue regions, thus assumption of uniform mu introduces little bias. The scatter correction was found to increase the image contrast significantly, i.e., rCBF increased by 20%-30% in gray matter and decreased in white matter regions by 10%-20% after scatter correction, increasing gray-to-white ratio to be close to that of PET measurement. The rCBF values from the two scatter correction were not significantly different, but the triple-energy window technique suffered from increased noise. After scatter correction, rCBF values were in good agreement with those measured by PET.

CONCLUSION

This study shows little loss in accuracy results from assuming uniform mu map. However, scatter correction is required for the quantitative rCBF values and gray-to-white ratios to approach those of PET.

[Usefulness of a new technique to assess drug perfusion pattern on balloon occluded arterial infusion therapy (BOAI) for intrapelvic malignant neoplasms: subtraction CT with low-flow-rate arterial injection (S-CTLA)]

The hemodynamics in balloon occluded arterial infusion therapy (BOAI) for intrapelvic malignant neoplasms is not totally understood. A new technique to evaluate the perfusion pattern of anticancer drugs under BOAI, which is named Subtraction CT with Low-flow-rate Arterial injection (S-CTLA), has been developed by us. In this technique, spiral CT data were acquired twice, before and after low-flow-rate (0.2 ml/sec) injection of contrast agent. Then, subtraction images were reconstructed. S-CTLA was performed in 3 patients with urinary bladder cancer. Our results provided demonstrable images as well as useful information in predicting the effectiveness of BOAI.

Superantigenicity of helper T-cell mitogen (SPM-2) isolated from culture supernatants of Streptococcus pyogenes

A superantigen (Streptococcus pyogenes mitogen-2; SPM-2) that stimulates human helper T cells bearing unique types of variable domains of T-cell receptor beta-chain (TCR V beta) was isolated from the culture supernatant of S. pyogenes strain T12. The active molecule isolated by diethylaminoethyl (DEAE)-cellulose chromatography and isoelectric focusing was a protein with a molecular weight (MW) of 29,000 and isoelectric point (pl) of 6.0. This new superantigen was found to activate preferentially V beta 4+, 7+, and 8+ T cells, whereas recombinant streptococcal pyrogenic exotoxin A and C activated V beta 12+ and V beta 2+ T cells, respectively, as determined by flow cytometry and reverse transcriptase-polymerase chain reaction (RT-PCR) methods. This proliferative response was significantly inhibited by anti-HLA-DR monoclonal antibody, and required paraformaldehyde-fixed antigen-presenting cells (APC), indicating that this action is dependent on major histocompatibility complex (MHC) class II molecules without processing. Analysis of the amino-terminal amino acid sequence of the molecule failed to find any identical or significantly homologous proteins. We have previously reported that cytoplasmic membrane-associated protein (CAP), a streptococcal superantigen isolated from the cell membranes of S. pyogenes T12 strain, stimulated mainly V beta 8+ T cells. Both SPM-2 and CAP preferentially stimulated helper T cells, and rabbit antiserum against SPM-2 completely neutralized the T-cell-stimulating activities of CAP, suggesting that SPM-2 and CAP belong to a family of streptococcal mitogenic proteins. The SPM-2 activity with stimulation of V beta 8+ T cells was detected extensively in the culture fluids of group A streptococci, but not in those of other streptococcal species, including groups B and D streptococci, and most of the activities detected were completely inhibited by anti-SPM-2 serum. These results indicate that SPM-2 may be a newly discovered superantigen molecule, which can be commonly synthesized by group A streptococci.

Accessory cell function of a human colonic epithelial cell line HT-29 for bacterial superantigens

The expression and up-regulation of cell adhesion molecules on a human colonic epithelial cell line HT-29, and the peripheral blood T lymphocyte proliferation responses to bacterial superantigens presented by this cell line were investigated, compared with peripheral blood monocytes. In HT-29 cells, there was constitutive expression of intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen-3 (LFA-3) at a low level, but no constitutive expression of HLA-DR, LFA-1, B7-1 and B7-2 molecules. After stimulation with the supernatants of staphylococcal enterotoxin B (SEB)-stimulated peripheral blood mononuclear cells for 48 h, there was significant up-regulation of HLA-DR and ICAM-1 molecules (both > 90% positive). However, this stimulation had no effect on the expression of LFA-1, B7-1, B7-2 and LFA-3 molecules. In the presence of all tested superantigens SEB, toxic shock syndrome toxin-1, and streptococcal pyogenic exotoxin A, stimulated HT-29 cells caused significant T cell proliferation. When monocytes were used as antigen-presenting cells (APC), the MoAbs against HLA-DR, B7-2 and LFA-3 showed a significant inhibition of SEB-induced T cell proliferation. Anti-ICAM-1 MoAb had no effect on this response. On the other hand, when stimulated HT-29 cells were used as APC, the MoAbs against HLA-DR and ICAM-1 significantly inhibited SEB-induced T cell proliferation. In contrast to monocytes, anti-B7-2 and anti-LFA-3 had no effect on this response. SEB could not induce HT-29 cells to produce IL-8 directly; however, SEB significantly induced the stimulated HT-29 cells to produce IL-8 in the presence of T cells. Thus these data demonstrate that the products of superantigen-stimulated T cell activation can increase the expression of HLA-DR and ICAM-1 molecules on HT-29 cells significantly. Stimulated HT-29 cells can serve as APC to bacterial superantigens. This response is an HLA-DR- and ICAM-1-dependent, but B7-2- and LFA-3-independent process, which was different from professional APC monocytes.

Osteoclast precursors in bone marrow and peritoneal cavity

Osteoclasts differentiate from cells that share some phenotypes with mature macrophages and monocytes, but early precursors for osteoclasts still remain obscure. To characterize osteoclast precursors, using monoclonal anti-c-Fms and anti-c-Kit antibodies, bone marrow cells were separated and the frequency of clonogenic progenitors were measured. Osteoclast precursors in the bone marrow mainly expressed c-Kit and diminished in frequency when they expressed c-Fms. In contrast to bone marrow, the precursors in the peritoneal cavity were enriched with a population of c-Fms+. Injection of these antibodies into mice demonstrated that peritoneal osteoclast precursors were sensitive to anti-c-Fms but not to anti-c-Kit antibodies, whereas those in bone marrow only declined in the presence of both antibodies. Meanwhile, c-Fms as opposed to c-Kit played an essential role in the generation of osteoclasts in cultures. We also compared osteoclast precursors with colony forming cells (CFU-M) by a macrophage colony stimulating factor. CFU-M in bone marrow decreased when anti-c-Kit antibody was administered and no CFU-M was detected in peritoneum. In this study, we show differences between proliferative potential osteoclast precursors maintained in bone marrow and peritoneum and between CFU-M and osteoclast precursors.

Isolation of a new superantigen with potent mitogenic activity to murine T cells from Streptococcus pyogenes

A mitogenic substance on murine lymphocytes was detected in the culture supernate of Streptococcus pyogenes type 12 strain. This substance had a molecular weight of 28,000 and pI 9.2, and was designated as S. pyogenes mitogen (SPM). The proliferative response of C3H/HeN spleen cells began at 1 ng ml-1 and reached a maximal response at 100 ng ml-1 of SPM for 4 days culture. Anti-Thy 1.2 mAb and complement-treated spleen cells abrogated the proliferative response to any dose of SPM. Although the anti-major histocompatibility complex class 1 mAbs had no blocking effect on proliferation by SPM, this proliferation was substantially inhibited by the addition of either anti-I-A or anti-I-E mAb, and complete inhibition was produced by the addition of both mAbs. Fixed antigen-presenting cells still induced T cell proliferation by SPM. A significant expansion of T cells bearing V beta 13 T-cell receptor was observed up to 73% among the Thy 1.2+ cells in cultures stimulated with SPM, indicating expansion in a V beta-specific manner. Immunoblotting of IEF-separated proteins showed that anti-streptococcal pyrogenic exotoxin (SPE) C reacted with a protein of pI 6.9 and anti-SPEB did not show any reactivity. SPEA was reported to expand V beta 8.1 and 8.2 bearing murine T cells, and SPM did not. SPM also exhibited potent mitogenic activity on human T cells and V beta 21+ T cells were selectively expanded. These results lead to the conclusion that SPM was neither SPEA, B nor C, but a new protein belonging to a group of streptococcal superantigens with activity on not only human but also murine lymphocytes.

Effect of culture conditions on artificial activation of porcine oocytes matured in vitro

The effects of culture media used and culture period for in vitro maturation of porcine oocytes on their subsequent response to chemical and electrical activation, were investigated. Activated oocytes were identified by the presence of a pronucleus(ei) or cleavage. Porcine oocytes were cultured for 24, 30, 36, 42 and 48 h in TCM199 with Earle's salts (199) supplemented with 10% fetal calf serum (199-FCS) before electrical stimulation. Although few oocytes were activated after 24 h and 30 h of culture (5.4% and 6.1% respectively), the percentage of activated oocytes increased significantly to 93.2% after 42 h in culture (P < 0.05); however, when the culture period was extended to 48 h, there was a significant decrease to 56.7% (P < 0.05). Oocytes were also cultured in four types of media: (1) 199-FCS; (2) 199 supplemented with 5 mg mL-1 bovine serum albumin (199-BSA); (3) Kreb's-Ringer bicarbonate solution supplemented with 10% FCS (KRB-FCS); and (4) KRB supplemented with BSA (KRB-BSA). After 42 h of culture in each medium, the oocytes were electrically activated. Although rates of maturation of oocytes cultured in the four media were similar (74.0-80.8%), all oocytes except those cultured in 199-FCS failed to be activated. In addition, oocytes were cultured for 36, 42 and 48 h in 199-FCS and then stimulated by treatment with ethanol. Significantly fewer oocytes were activated in the chemically-treated group than in the electrically-treated group. These results indicate that culture conditions used for the culture of porcine oocytes in vitro are important with respect to their subsequent response to artificial activation.

Acute subarachnoid hemorrhage: MR imaging with fluid-attenuated inversion recovery pulse sequences

PURPOSE

To evaluate the usefulness of fluid-attenuated inversion recovery (FLAIR) magnetic resonance (MR) imaging sequences in the detection of acute subarachnoid hemorrhage (SAH).

MATERIALS AND METHODS

MR imaging with FLAIR sequences was performed with a 0.5-T superconducting unit in 20 patients (aged 30-72 years) with acute SAH due to a ruptured aneurysm and in 27 control subjects (aged 32-72 years). FLAIR images were obtained 2 hours to 2 days after ictus. Findings were evaluated and compared with computed tomographic (CT) findings.

RESULTS

In all patients, acute SAH was clearly demonstrated as an area with signal intensity that was high relative to that of the normal cerebrospinal fluid and surrounding brain parenchyma at FLAIR imaging. This sequence was especially useful in demonstration of acute SAH in the posterior fossa, which was difficult to show at CT because of beam-hardening artifacts. In a double-blind comparison, no FLAIR images acquired in control subjects were confused with those acquired in control subjects were confused with those acquired in patients.

CONCLUSION

FLAIR sequences reliably provide diagnostic images in patients with acute SAH.

Collaborative work to determine the optimal administration period and parameters to detect drug effects on male rat fertility--study on estradiol benzoate effects

In order to examine the optimal administration period and parameters for male fertility assessment, male rats were subcutaneously administered 0.2, 2 or 20 micrograms/kg of estradiol benzoate (E2B), a known testicular toxicant, for 4 weeks or 9 weeks before mating. After 4 weeks administration, suppression of body weight gain and food consumption, decreases in prostate and seminal vesicle weights, atrophy of Leydig cells, and mature spermatid retention at stages IX, X and XI were observed in the 2 and 20 micrograms/kg groups. In the 20, micrograms/kg group, decreases in epididymides weight and copulation index were also found but the number of sperm and sperm motility were not affected. In the 0.2 micrograms/kg group, no changes were noted in any parameters. After 9 weeks administration, decreases in testis weight and the number and motility of sperm were observed in the 20, micrograms/kg group, in addition to the changes found after 4 weeks administration. These results suggest that detailed histopathological evaluation and determination of accessory sex organ weights are sensitive for evaluating the effects of E2B on male fertility. Results with the 4-weeks treatment were comparable to those with the 9-weeks treatment in terms of these parameters.

Immunological detection and characterization of an estrus-associated antigen in the goat oviduct

The present study was designed to investigate the possibility that the goat oviduct produces specific substance(s) similar to the oviductal glycoprotein (BOGP) of the bovine oviduct. Oviductal flushings obtained from goats at the follicular and luteal phases of the estrous cycle were examined by immunoblotting for the presence of material that cross-reacted with monoclonal antibodies (MAbs) specific for BOGP. The MAbs immunoreacted with a broad band with a molecular mass of protein of about 97 kDa in the flushings of goat oviducts after fractionation of proteins by electrophoresis under reducing conditions. The antigen was present in flushings obtained from the ampullar segments of oviducts from goats at the follicular stage, but this antigen could hardly be detected in the flushings from the ampulla at the luteal phase and or the flushings from the isthmus at either the follicular or the luteal phase. This antigen was not detected in uterine flushings, follicular fluid, or serum. An immunohistochemical study demonstrated that the MAbs reacted specifically with the epithelial cells of the goat oviduct. Intense labeling was observed in the ampullar and fimbrial epithelia of goat oviducts at the follicular phase, but the immunohistochemical reaction was very weak at the luteal phase. In the isthmus, the reaction was faint during both the follicular and the luteal phase. No specific immunohistochemical reactivity with the MAbs was observed with other tissues from the reproductive tract or with nonreproductive tissues. Immunofluorescent staining showed that the antigen was associated with the zona pellucida of goat ovarian eggs that had been incubated with ampullar flushings from goats at the follicular stage.(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of aneuploidy in Chinese hamster oocytes following in vivo treatments with trimethoxybenzoic compounds and their analogues

Many inhibitors of tubulin polymerization have a trimethoxybenzene ring in their molecules. Such trimethoxybenzoic compounds and their analogues may therefore have a potency to induce meiotic nondisjunction of oocytes. In this study, a single dose of reserpine (0.5 microgram/g body weight), podophyllotoxin (20.0 micrograms/g b.w.), trimethoxybenzoic acid (500.0 micrograms/g b.w.) or vinblastine sulfate (3.0 micrograms/g b.w.) was injected intraperitoneally to mature female Chinese hamsters at the onset of the first meiotic spindle formation of oocytes. Within 6 h after spontaneous ovulation, MII oocytes were collected from the oviducts for morphological examination and cytogenetic analysis. The incidence of morphologically abnormal oocytes with unusually large first polar body or bodies increased significantly after the treatment with reserpine (18/202; 8.9%), podophyllotoxin (28/172; 16.3%) and vinblastine sulfate (63/197; 32.0%), as compared with the control (3/214; 1.4%). Chromosome analysis of oocytes revealed that podophyllotoxin and vinblastine sulfate were effective in inducing aneuploidy (62/154; 40.3% and 128/156; 82.1% vs. 3/198; 1.5% of the control) by inhibiting the formation of spindle microtubules at the first meiosis. Aneuploids were found more frequently in morphologically abnormal oocytes than in normal oocytes. No aneugenic activity of reserpine and trimethoxybenzoic acid was observed. These results indicate that trimethoxybenzoic compounds do not necessarily exhibit aneugenic activity.

Chicken oocyte growth is mediated by an eight ligand binding repeat member of the LDL receptor family

Deposition of the yolk mass components of chicken oocytes, very low density lipoprotein (VLDL) and vitellogenin (VTG), is mediated by a 95 kDa plasma membrane protein, termed VLDL/VTG receptor (VLDL/VTGR). Molecular characterization of the VLDL/VTGR revealed that it is a member of the LDLR gene superfamily, and harbours eight complement-type, cysteine-rich ligand binding repeats at the N-terminus. This ligand binding domain structure is the hallmark of the recently discovered mammalian so-called VLDLRs, whose true physiological function remains to be elucidated. Northern blot analysis revealed that this receptor is expressed almost exclusively in oocytes, with very much lower levels of hybridizing transcripts present in heart and skeletal muscle. Heterologous expression of the cloned receptor demonstrated its ability to bind both VLDL and VTG. The receptor gene is located on the avian sex chromosome Z, in agreement with the sex linkage of a single-gene defect in animals that fail to reproduce because of the lack of expression of functional VLDL/VTGR. In situ hybridization analysis of oocytes suggested that VLDL/VTGR mRNA may relocalize during oocyte growth. Thus, the current study has identified and characterized the first non-mammalian VLDLR. Its key role in avian reproduction and extremely high evolutionary conservation shed new light on VLDLR function in mammals, which also express the gene in ovaries.

Increase in testis weight of hereditary dwarf rats (rdw/rdw) with advancing age

Testis weight and seminal vesicle weight (relative to total body weight) in rdw rats and N rats were compared with advancing age. The results obtained were as follows 1) The increase in testis weight became remarkable at 15-16 weeks of age. The weight remained constant up to 23-30 weeks of age and decreased thereafter with age. 2) Seminal vesicle weight increased rapidly in rdw rat at 15-16 weeks of age, reflecting elevated androgen secretion and sexual maturation. 3) From the viewpoint of histology, one of causes of the increase in testis weight may be edema. The increase in testis weight coincided with the increase in androgen secretion at 15-16 weeks of age as suggested by the relative increase in seminal vesicle weight.

Influence of arterial partial pressure of carbon dioxide on cerebral MRA in normal volunteers

OBJECTIVE

Signal intensity of MR angiography (MRA) is influenced by the physiological factors of flowing blood in the vessels. We examined whether MRA can detect a cerebral hemodynamic change induced by reducing or elevating the arterial partial pressure of carbon dioxide (PaCO2).

MATERIALS AND METHODS

Cerebral MRA was performed in six normal volunteers, each having three measurements during hyperventilation, normal breathing, and 7% CO2 inhalation. The MRA data were obtained by a 0.5 T wholebody scanner and a time-of-flight technique of three-dimensional GE imaging. In addition to the visual inspection, the signal intensity and the lengths of the middle cerebral artery (MCA) and posterior cerebral artery (PCA) were estimated in relation to PaCO2.

RESULTS

The MRA appearances of major cerebral arteries were remarkably different depending on the breathing conditions. There was significant difference in the mean signal intensity (p < 0.01) and the mean length (p < 0.01) of the MCA and PCA between the hyperventilation and normal breathing trials.

CONCLUSION

The MRA signal was sensitive to the changes in PaCO2 level of flowing blood. This phenomenon may result from changes in the velocity of blood flow in major cerebral arteries.

The controlled release of prednisolone using alginate gel

In a release study of alginate gel beads, swelling and erosion of the beads were observed at pH 6.8, whereas no swelling occurred at pH 1.2. The amount of released prednisolone (PL) was greater at pH 6.8 than at pH 1.2. The lower the ratio of mannuronic acid block to guluronic acid block in alginate, the slower the release of PL. An increase in loaded PL in the beads resulted in a slower release of PL. The decrease in bead size caused a rapid release of PL. The addition of sodium alginate propylene glycol ester elevated the extent of PL release. The plasma profile of PL showed sustained-release behavior after the oral administration of the beads to beagles. Furthermore, the correlation between in vitro release and in vivo absorption of PL for various alginate gel beads was evaluated using deconvolution and convolution methods. The in vivo absorption of PL was correlated with the PL release at pH 1.2, and it differed from that at pH 6.8. The release of PL from alginate gel beads in vivo appeared to occur under conditions that cause little swelling.