Topological rules for membrane protein assembly in eukaryotic cells

Insertion into the endoplasmic reticulum membrane of model proteins with one, two, and four transmembrane segments and different distributions of positively charged residues in the N-terminal tail and the polar loops has been studied both in vitro and in vivo. Membrane insertion of these same constructs has previously been analyzed in Escherichia coli, thus making possible a detailed comparison between the topological rules for membrane protein assembly in prokaryotic and eukaryotic cells. In general, we find that positively charged residues have similar effects on the membrane topology in both systems when they are placed in the N-terminal tail but that the effects of charged residues in internal loops clearly differ. Our results rule out a sequential start-stop transfer model where successive hydrophobic segments insert with alternating orientations starting from the most N-terminal one as the only mechanism for membrane protein insertion in eukaryotic cells.

Systemic immediate-type reactions to gelatin included in Japanese encephalitis vaccines

Three children had systemic immediate-type reactions to Japanese encephalitis (JE) vaccine which contains gelatin as a stabilizer. We found that all the children had anti-gelatin IgE in their sera. Further, two of the three also had experienced systemic allergic reactions to gelatin-containing foods before the vaccination. We assume that the systemic allergic reactions to JE vaccines might be caused by gelatin in the JE vaccine.

The highly conserved DAD1 protein involved in apoptosis is required for N-linked glycosylation

BACKGROUND

The tsBN7 cell line is one of the temperature-sensitive mutants for cell proliferation which have been isolated from the BHK21 cell line derived from the golden hamster. It has a mutation in the DAD1 gene encoding a 12.5kDa highly conserved protein through evolution, and enters apoptosis at the restrictive temperature due to this mutation.

RESULTS

DAD1 was recovered in light membrane fractions after differential centrifugation. It could not be released from the membrane, even by carbonate extraction, without a detergent. Upon digestion with proteinase K, both N and C terminal portions-but not the middle portions of DAD1- were released from the membrane. Thus, DAD1 appears to be an integral membrane protein in which both termini are located in the cytosol. DAD1 was localized in the endoplasmic reticulum. In accordance with a similarity to the yeast protein Ost2p, which is a subunit of the oligosaccharyltransferase, at the restrictive temperature, loss of DAD1 function caused a defect of N-linked glycosylation in tsBN7 cells resulting in apoptosis. However, tunicamycin, which is known to inhibit N-linked glycosylation did not induce apoptosis in either tsBN7 or BHK21 cells.

CONCLUSION

tsBN7 cells have a defect in N-linked glycosylation caused by the loss of DAD1.

Clinical significance of the subjective vertical in patients with unilateral vestibular disorders

The subjective vertical was estimated by using a concentrically movable spotlight-line on a specially devised dome-shaped screen and a controller in patients with unilateral vestibular disorders. The test was performed in a dark room to measure the deviation of the subjective vertical from the true vertical to the earth gravity. The result showed characteristic deviation of the subjective vertical to the affected ear side in most subjects. The relationship between the subjective deviation and body sway was investigated to estimate the clinical significance of the subjective vertical. The locus pattern, area, locus length and the trajectory of head movements while measuring the subjective vertical were recorded. The patterns were centripetal or right-left types, the values of the head movement seemed to be proportional to the magnitude of the subjective vertical. The time course of the subjective vertical depended on the stage of the disorder. Some cases with active vestibular disorders showed directional changes of the subjective vertical deviation depending on the extent of the lesion. The most interesting results were obtained in the relationship between the caloric response and the subjective vertical, suggesting the clinical significance of the subjective vertical in vestibular function.

Identification and functional characterization of yeast zeta-COP

Coatomer, the cytosolic protein complex, consists of seven subunits (alpha-, beta-, beta'-, gamma-, delta-, epsilon-, and zeta-COP) and is involved in vesicle trafficking early in the secretory pathway in collaboration with a 20 kDa GTP-binding protein (ARF). In the present study, we have identified a yeast gene which encodes a protein having 39% amino acid sequence identity with bovine zeta-COP. This gene (YZC1 for Yeast Zeta COP) is essential for vegetative growth and the growth defect of delta yzc1 cells was restored by bovine zeta-COP cDNA. We isolated a temperature-sensitive mutant of YZC1 (yzc1ts) and examined its capacity for both the ER-to-Golgi transport and the double lysine motif (KKXX)-mediated retrograde transport from Golgi to ER. At non-permissive temperature, the yzc1ts cells exhibited a weak defect in the anterograde transport, but a strong defect in the retrograde vesicle transport. We conclude that Yzc1p is a yeast homologue of mammalian zeta-COP and participates mainly in the Golgi-to-ER retrograde transport.

[Detection of microemboli in patients with extracranial carotid artery stenosis by transcranial Doppler sonography]

Embolism from a stenotic lesion of the extracranial internal carotid artery (ICS) is considered to be an important pathomechanism of cerebral infarction. The purpose of this study is to estimate the risk of cerebral infarction associated with microembolism in patients with ICS and thereby to determine the importance of TCD-detected microemboli in this condition. Seventy-one cases with more than 30% ICS and 10 cases without ICS were studied. TCD monitoring was carried out for an hour at the ipsilateral middle cerebral artery of each case using a 2-MHz pulse-wave transcranial Doppler device. High intensity transient signals were counted as microemboli. Microemboli were detected in 27 of 71 cases with ICS, but not in cases without ICS. Microemboli were detected more frequently in cases with 70% to 99% ICS (53.3%) compared with in cases with 30% to 69% ICS (12.5%). Cerebral infarctions were recognized in the ipsilateral hemisphere in 23 of 27 cases with microemboli (85.2%) by means of MRI. In contrast, cerebral infarctions were recognized only in 21 of 45 cases without microemboli (47.7%). These results suggest that a stenotic lesion of the extracranial internal carotid artery, especially high-grade stenosis, is a major source of cerebral embolism and that detection of microemboli by TCD is a useful tool capable of reliably assessing the risk of cerebral infarction due to ICS.

Responses of monkeys with pollinosis to two major allergens of Japanese cedar pollen

We examined the responses of two Japanese monkeys with pollinosis to two major allergens (Cry j 1 and Cry j 2) of Japanese cedar pollen. The two monkeys (A and B) had specific IgE antibodies to the allergens and showed a strong positive reaction to both of them in the intradermal test. In the histamine release test with peripheral blood mononuclear cells (PBMC), monkey A showed a typical pattern similar to that seen in human patients, while monkey B released a low level of histamine. The proliferative response of PBMC to both allergens in monkey A was weak, but was typical in monkey B. From clinical as well as immunological points of view, these monkeys may be a suitable animal model for Japanese cedar pollinosis in humans.

Insertion of tandem direct repeats consisting of avian leukosis virus LTR sequences into the inverted repeat region of Marek's disease virus type 1 DNA

The BC-1 strain DNA of Marek's disease virus type 1 (MDV1) at high-passage in culture was found to contain tandem direct repeats of the complete long terminal repeat (LTR) sequence of avian leukosis virus RAV0 strain as the repeat unit within the short inverted repeats of the MDV1 DNA. Since the attenuated BC-1 strain grows well in cultured cells, the insertion site for retroviral DNA sequence within the short inverted repeat of MDV1 DNA is not essential for viral growth in culture.

Vestibulo-ocular reflex and visual vestibulo-ocular reflex during sinusoidal rotation in children

To clarify the relationship between vestibular and visual (optokinetic) stimuli in normal children, we investigated the vestibulo-ocular reflex (VOR) and visual VOR (VVOR). The subjects were 20 healthy children aged 3-6 years and 24 healthy adults aged 21-29 years. The VOR gains and phase were measured under two visual conditions: with eyes open in complete darkness and with eyes open in a lighted optokinetic drum. In both visual conditions, phase did not significantly differ between children and adults. In the dark, children presented a significantly larger gain than that of adults. In the optokinetic drum, however, the gain values of the children were almost the same as in adults. We suggest that the large VOR gain values of children may be due to immaturity of the inhibitory regulation system of the VOR.

Food allergy to gelatin in children with systemic immediate-type reactions, including anaphylaxis, to vaccines

BACKGROUND

Anaphylaxis to measles-mumps-rubella vaccines has been reported. We have suspected that most such reactions are caused by gelatin contained in the vaccines.

OBJECTIVE

To confirm the relation between systemic allergic reactions to vaccines and the presence of anti-gelatin IgE, we measured anti-gelatin IgE in children who demonstrated allergy to gelatin-containing vaccines. Furthermore, to clarify the relation between allergic reactions to gelatin in vaccines and foods, we surveyed the occurrence of allergic reactions to gelatin-containing foods in the same children.

METHODS

Serum samples were taken from 26 children who had systemic immediate-type reactions, including anaphylactic shock, to vaccines and the same number of children without allergic reactions. Specific IgE to gelatin in these samples was measured. We then surveyed whether these children had allergic reactions to gelatin-containing foods before and after vaccination.

RESULTS

Twenty-four of the 26 children with allergic reactions to vaccines had anti-gelatin IgE ranging from 1.2 to 250 Ua/ml. Seven had allergic reactions on ingestion of gelatin-containing foods. Of these, two had reactions before vaccination, and five had reactions after vaccination. All the control children without allergic reactions to vaccines had no anti-gelatin IgE.

CONCLUSION

We reconfirmed a strong relationship between systemic immediate-type allergic reactions, including anaphylaxis, to vaccines and the presence of specific IgE to gelatin. Moreover, some of the children also had allergic reactions to food gelatin before or after vaccination.

Evaluation of the radiosensitizing effects of RK28 intravenous, intraarterial, and intratumoral injections on the rabbit VX2 tumor system

PURPOSE

To evaluate the differences in the radiosensitizing effects of intravenous (i.v.) injection, intraarterial (i.a.) injection, and intratumoral (i.t.) injections of the hypoxic cell radiosensitizer RK28 ([1-(4'-hydroxy-2'-butenoxy)methyl-2-nitroimidazole], a 2-nitroimidazole with an acyclic sugar analogue substituted at the N-1 position of the imidazole ring) using an animal experimental system.

METHODS AND MATERIALS

Rabbit VX2 tumors, which were implanted in the muscle of left hind legs and grown to 3 cm in diameter, were treated with RK28 (80 mg/kg x b.wt.) before 15 Gy of local x-ray irradiation. The auricular vein and the left saphenous artery were used for systemic injection and regional injection, respectively. For i.t. injection, a 21-gauge needle with three lateral holes was positioned in the central area of the tumor. Tumor regression was precisely evaluated by computed tomograpy (CT), and survival time was also studied. Using high-performance liquid chromatography (HPLC), pharmacokinetic studies for RK28 and its seven major metabolites were performed in tumor and serum at 0, 10, 20, 30, and 60 min after drug injection was completed.

RESULTS

Radiosensitizing effects of RK28 were considered present after i.a. injection (p < 0.05) and i.t. injection (p < 0.05) after analyzing tumor volumes on day 21 after treatment. Increased survival was not observed in any group with RK28 injection compared with survival in the group treated by x-ray irradiation alone. Pharmacokinetic studies showed the average concentration of RK28 in the tumor during x-ray irradiation was 1.3 times higher after i.a. injection and 3.5 times higher after i.t. injection than that after i.v. injection. The time modifying factor50 (TMF50: ratio of time for tumor to decrease by 50%, radiation alone vs. radiation plus drug) was calculated to be 1.5 after i.v. injection, 1.7 after i.a. injection, and 2.3 after i.t. injection. The values of TMF50 correlated to the average concentrations of RK28 in the tumor. As to metabolites of RK28, beta-glucuronated compound and cysteine conjugate were highly detected. The concentrations of cysteine conjugate were higher in the tumor than in serum via i.v. injection.

CONCLUSIONS

Radiosensitizing effects of RK28 were observed on the rabbit VX-2 tumor system after i.a. or i.t. injection. Pharmacokinetic studies proved that radiosensitizing effects depended on the concentration in the tumor, though the administration routes were different. Combined forms with nonprotein thiols were detected. However, survival benefits were not obtained by RK28. For clinical applications of RK28, i.a. or i.t. injection could facilitate better local control of cancer.

Identification of the first major allergen of a squid (Todarodes pacificus)

BACKGROUND

In Japan, squid is an important seafood, and some patients with food allergies are sensitive to squid. There has been no report, however, describing the major allergens of squid.

OBJECTIVE

To characterize squid allergens, we isolated a major allergen from the Pacific flying squid (Todarodes pacificus) and compared it with a major allergen from a shrimp (Penaeus orientalis).

METHODS

The major squid and shrimp allergens were isolated by column chromatography on diethylaminoethyl-Sepharose (Pharmacia, Uppsala, Sweden), hydroxylapatite, and Sephacryl S-300 (Pharmacia). The IgE reactivity of the isolated allergens was assessed by immunoblotting. The cross-reactivity between the squid and shrimp allergens was examined by use of mouse polyclonal and monoclonal antibodies to the major allergens. Amino acid sequence analyses of the isolated allergens were done.

RESULTS

The isolated squid allergen is a 38 kd, heat-stable protein. IgE antibody binding to the purified squid allergen was demonstrated by immunoblotting. Cross-reactivity between major squid and shrimp allergens was demonstrated with sera from patients allergic to squid or shrimp or with allergen-specific monoclonal antibodies. The amino acid sequence analysis of the major squid allergen showed a marked homology with tropomyosin from blood fluke planorbid (Biomphalaria glabrata), which is a common vector snail of Schistosoma mansoni.

CONCLUSION

This 38 kd protein is a major allergen of the squid, Todarodes pacificus, and is believed to be squid muscle protein tropomyosin. We named it Tod p 1 according to International Union of Immunological Societies allergen nomenclature regulation.

[Evaluation of efficacy for Japanese cedar pollen-specific immunotherapy by lymphocyte proliferation test]

Peripheral mononuclear cells from 47 patients suffering from Japanese cedar pollinosis were stimulated with crude pollen extract of Cryptomeria Japonica (CJ) to evaluate the effect of CJ-specific immunotherapy. The stimulation index (SI) with crude pollen extract of CJ in the patients with excellent and good clinical outcome was significantly lower than those with poor outcome. The SI increased with the increasing symptoms in a dose dependent manner. In the patients under immunotherapy for long period, the good clinical outcome and low SI were gained. These results suggest that peripheral lymphocyte proliferation test should be a good objective indicator for allergen-specific immunotherapy.

Effects of atipamezole, an alpha 2-adrenergic antagonist, and somatostatin on xylazine-induced growth hormone release in calves

In order to clarify the mechanism of xylazine-induced GH release, we investigated the effects of atipamezole, a selective alpha 2-adrenergic antagonist, and somatostatin (SRIF) on xylazine-stimulated GH release in calves. Xylazine injection (0.30 mg/kg BW, iv) induced a rapid increase in the GH concentration. When atipamezole was used in combination with xylazine, it blunted the increase in the plasma GH concentration induced by the xylazine injection. The GH levels at 15-50 min after the simultaneous injection of xylazine and atipamezole were significantly (P < 0.05) lower than the corresponding values in the animals given xylazine alone. The area under the GH response curve for 120 min after the simultaneous injection of xylazine and atipamezole was significantly (P < 0.05) smaller than that for the xylazine alone. A series of five intravenous injections of 1 mg of SRIF at 10-min intervals also blunted xylazine-stimulated GH release. Atipamezole partially suppressed xylazine-induced hyperglycemia, but SRIF completely suppressed the hyperglycemia for the first 60 min after the xylazine injection and the suppression by SRIF was stronger than that by atipamezole. On the other hand, both atipamezole and SRIF failed to blunt xylazine-induced hypoinsulinemia. The present results suggest that xylazine stimulates GH release via the alpha 2-adrenergic pathway in cattle, but the mechanism of xylazine-induced hyperglycemia remains to be determined.

Effects of the Robertsonian translocation on fertilization rates and preimplantation development of bovine oocytes in vitro

A study was conducted to investigate the effect of the 7/21 Robertsonian translocation on fertilization and subsequent development of bovine oocytes matured in vitro. Semen from Japanese Black bulls, 2 with a normal karyotype (Bulls A and B) and 2 that were heterozygous for the 7/21 translocation (Bulls C and D), was used in this study. In vitro matured bovine oocytes were inseminated with frozen-thawed sperm capacitated with heparin. After insemination, oocytes were cultured at 38.5 degrees C on a monolayer of cumulus cells in TCM-199 supplemented with 5% superovulated cow serum and 0.5 mM sodium pyruvate in an atmosphere of 2% CO2 in air. Cleavage rate was evaluated at 54 h after insemination, and development of embryos to the blastocyst stage was observed 7 to 10 d post insemination. There was no difference in the fertilization rate among the 4 bulls. Although the cleavage rate of oocytes inseminated with semen from Bull C (heterozygote) was lower (P < 0.05) than that obtained with semen from Bull B (normal), the blastocyst formation rate did not differ among the 4 bulls. These results indicate that the 7/21 Robertsonian translocation had no effect on the fertilization and blastocyst formation rates of bovine in vitro-matured oocytes.

Diurnal variation in intragastric pH in children with and without peptic ulcers

Diurnal variation in intragastric pH in children with peptic ulcers has not been previously reported. Therefore, we monitored intragastric pH during a 24-h period in 82 subjects (10 children with gastric ulcers, 9 children with duodenal ulcers, 58 non-ulcer (comparison group) children, and 5 healthy adults) using a monopolar glass pH electrode. The percent of readings below pH 2, 3, 4, and 5 for each subject was calculated and compared between the comparison group and the two ulcer groups using means and slopes (i.e. changes in percent with age for each group) of percent readings for each pH analysis. In the comparison group children, gastric acidity increased with age and reached adult levels by 14 y. Mean readings for all pH analyses in gastric ulcer children were lower than those in age-adjusted comparison children (p < 0.05). The slopes of the relationships between age and the percent time below any pH for the gastric ulcer group were different from those in the comparison group (p < 0.05) and were negative for all pH analyses. The mean time below pH 2 in children with duodenal ulcers was greater than that in age-adjusted comparison children (p = 0.002). The slope of the relationship between age and the percent time below pH 2 in the duodenal ulcer group was different from that in the comparison group (p < 0.05). Gastric acidity in children with primary gastric ulcers was reduced during childhood, but in children with primary duodenal ulcer, gastric acidity was at or above adult levels.

Structure, development, and maintenance of the nerve net of the body column in Hydra

The anatomy and developmental dynamics of the nerve net in the body column of Hydra viridissima were examined immunocytochemically with a monoclonal antibody (CC04) that recognizes an antigen in nerve cells and with an antiserum against vasopressin. CC04+ neuron cell bodies, their neurites, and vasopressin-like-immunoreactive (VLI+) neurites could be clearly visualized on whole-mount preparations. All neurites of the CC04+ neurons in the body column were VLI+. However, only half of the VLI+ neurites in the body column were CC04+. Immunocytochemical analysis of macerated preparations showed that half of the neurons in the gastric region of the body column were CC04+. These results suggest that most of the neurons in the gastric region are VLI+. The density of the VLI+ neurites was uniform along the entire length of the body column. The CC04+ neuron density in the gastric region remained constant at all stages of asexual development and during foot regeneration. After pulse-labeling with 5-bromo-2'-deoxyuridine (BrdU), CC04+ neurons with labeled nuclei appeared in the body column. We conclude that neuron density in the gastric region is maintained at a constant value by insertion of new neurons in parallel with continuous epithelial cell division.

[CA19-9 producing mixed gonadal germ-cell tumor in undescended testis located in abdomen. A case report]

A rare case of CA19-9 producing tumor in undescended testis was presented. A forty-three year old man visited to our hospital with a chief complaint of left flank pain. Serum tumor markers (AFP, beta-HCG, and CA19-9) were elevated. Abdominal CT scan demonstrated large solid mass with multilocular cysts were capsulated. The tumor resection was performed after 3 courses of CEB (Carboplatin, Etoposide, and Bieomycin) chemotherapy. Macroscopically, the tumor was consisted of necrotic mass and multilocular cysts. The tumor size was 25 x 8 x 5 cm and weight was 1000 g. Microscopically, the large part of tumor was necrotic due to chemotherapy, and the teratoma component which was consist of neural, muscular, and digestive tissue was seen in some area. In conclusion, this is a rare case of mixed germ-cell tumor in undescended testis located in abdomen.

Inhibition of collagen-induced platelet aggregation in Japanese black cattle with inherited platelet disorder, Chediak-Higashi syndrome

Aggregation properties of platelets were examined in Japanese Black cattle with Chediak-Higashi syndrome (CHS) and normal control cattle. Platelet aggregation induced by collagen was decreased in platelets of the cattle with CHS, but not ADP (10-20 microM), thrombin (0.5-1.0 U/ml) and phorbol-12-myristate 13-acetate (PMA, 3.2 microM). The aggregation response induced by collagen in CHS platelets lacks the change in shape which usually occurs in normal platelets. Simultaneous stimulation by collagen (10 micrograms/ml) + ADP (10 microM) is effective in restoring collagen-induced aggregating response in CHS platelet, although pretreatment of ADP (10 microM) could not restore the collagen (10 micrograms/ml)-induced aggregating response, suggesting that there is a certain threshold of stimulation intensity above which collagen-induced aggregation of CHS platelet can begin. Control normal platelets, previously exposed to ADP (10 microM) and collagen (10 micrograms/ml), showed no further response to exposure to a third aggregating agent (arachidonic acid, 5 mM). On the other hand, the final agent was able to elicit aggregating responses in CHS platelets, suggesting that the arachidonate aggregating system may be suppressed in CHS cattle, but fully activated in control animals. Furthermore, normal platelets showed a significant decrease in aggregating response to collagen when pretreated with a cyclooxygenase inhibitor, indomethacin (10(-5) M), whereas CHS platelet was insensitive to indomethacin. This indomethacin-treated normal platelet mimicked the CHS collagen-induced aggregation pattern. These data suggest that a signal transduction process from receptor-operated events to arachidonate metabolism is suppressed in collagen-induced CHS platelet aggregation.

Transgenic expression of L-gulono-gamma-lactone oxidase in medaka (Oryzias latipes), a teleost fish that lacks this enzyme necessary for L-ascorbic acid biosynthesis

Transfer of the gene for L-gulono-gamma-lactone oxidase, the missing enzyme in L-ascorbic acid biosynthesis in scurvy-prone animals, into medaka (Oryzias latipes) was successfully done. The expression plasmid pSVL-GLO, carrying rat liver L-gulono-gamma-lactone oxidase cDNA, was microinjected into the cytoplasm of fertilized eggs during the one-cell stage. Four male F0 fish having the transgene in their germ cells came to maturity, and F1 progeny derived from one of the F0 fish possessed L-gulono-gamma-lactone oxidase activity, indicating that the transgene was functionally expressed in the fish. Genomic Southern blot analysis demonstrated that the transgene existed in both chromosome-integrated and extrachromosomal forms.

Inversely correlated expression of p16 and Rb protein in non-small cell lung cancers: an immunohistochemical study

Cdk4-mediated phosphorylation of Rb protein is inhibited by p16, a product of a possible tumor suppressor gene. We examined the expression of p16 and Rb protein by means of immunohistochemistry in 61 non-small cell lung cancers and have demonstrated an inverse relationship between the expression of p16 and Rb protein: 28/30 specimens that did not stain for p16 stained for Rb and 21/31 p16-positive specimens did not stain for Rb. Only 1 of the p16-negative specimens had a mutation of exon 2 of the CDKN2 gene. Our results indirectly support the theory that p16 expression is negatively regulated by the functional Rb protein.

Protection of chickens from Newcastle disease by vaccination with a linear plasmid DNA expressing the F protein of Newcastle disease virus

To evaluate the usefulness of a DNA vaccine for chickens, we constructed a plasmid vector expressing the Newcastle disease virus F protein (NDV-F) under the control of the human cytomegalovirus immediate early enhancer and chicken beta-actin gene promoter. One-week-old chickens injected intramusculary with the circular plasmid DNA did not produce significant levels of antibody against NDV-F. However, two of five birds injected with the linearized plasmid DNA produced high levels of the antibody. Moreover, four of five birds injected with a mixture of the linearized-plasmid and Lipofectin produced the antibody efficiently. At 9 weeks post-injection, chickens were challenged with the velogenic NDV Sato strain. These chickens that had the antibody against NDV-F were protected from lethal NDV challenge. These results demonstrate that the DNA vaccine conferred efficient protection against the disease.