HIV-1 reverse transcriptase stability correlates with Gag cleavage efficiency: reverse transcriptase interaction implications for modulating protease activation

Proteolytic processing of human immunodeficiency virus type 1 particles mediated by viral protease (PR) is essential for acquiring virus infectivity. Activation of PR embedded in Gag-Pol is triggered by Gag-Pol dimerization during virus assembly. We previously reported that amino acid substitutions at the RT tryptophan repeat motif destabilize virus-associated RT and attenuate the ability of efavirenz (EFV, an RT dimerization enhancer) to increase PR-mediated Gag cleavage efficiency. Furthermore, a single amino acid change at RT significantly reduces virus yields due to enhanced Gag cleavage. These data raise the possibility of the RT domain contributing to PR activation by promoting Gag-Pol dimerization. To test this hypothesis, we investigated the putative involvement of a hydrophobic leucine repeat motif (LRM) spanning RT L282 to L310 in RT/RT interactions. We found that LRM amino acid substitutions led to RT instability and that RT is consequently susceptible to degradation by PR. The LRM mutants exhibited reduced Gag cleavage efficiencies while attenuating the EFV enhancement of Gag cleavage. In addition, an RT dimerization-defective mutant, W401A, reduced enhanced Gag cleavage via a leucine zipper (LZ) motif inserted at the deleted Gag-Pol region. Importantly, the presence of RT and integrase domains failed to counteract the LZ enhancement of Gag cleavage. A combination of the Gag cleavage enhancement factors EFV and W402A markedly impaired Gag cleavage, indicating a disruption of W402A Gag-Pol dimerization following EFV binding to W402A Gag-Pol. Our results support the idea that RT modulates PR activation by affecting Gag-Pol/Gag-Pol interaction. IMPORTANCE A stable reverse transcriptase (RT) p66/51 heterodimer is required for HIV-1 genome replication in host cells following virus entry. The activation of viral protease (PR) to mediate virus particle processing helps viruses acquire infectivity following cell release. RT and PR both appear to be major targets for inhibiting HIV-1 replication. We found a strong correlation between impaired p66/51RT stability and deficient PR-mediated Gag cleavage, suggesting that RT/RT interaction is critical for triggering PR activation via the promotion of adequate Gag-Pol dimerization. Accordingly, RT/RT interaction is a potentially advantageous method for anti-HIV/AIDS therapy if it is found to simultaneously block PR and RT enzymatic activity.

Effects of reduced gag cleavage efficiency on HIV-1 Gag-Pol package

BACKGROUND

HIV-1 pol, which encodes enzymes required for virus replication, is initially translated as a Gag-Pol fusion protein. Gag-Pol is incorporated into virions via interactions with Gag precursor Pr55^gag. Protease (PR) embedded in Gag-Pol mediates the proteolytic processing of both Pr55gag and Gag-Pol during or soon after virus particle release from cells. Since efficient Gag-Pol viral incorporation depends on interaction with Pr55^gag via its N-terminal Gag domain, the prevention of premature Gag cleavage may alleviate Gag-Pol packaging deficiencies associated with cleavage enhancement from PR.

RESULTS

We engineered PR cleavage-blocking Gag mutations with the potential to significantly reduce Gag processing efficiency. Such mutations may mitigate the negative effects of enhanced PR activation on virus assembly and Gag-Pol packaging due to an RT dimerization enhancer or leucine zipper dimerization motif. When co-expressed with Pr55^gag, we noted that enhanced PR activation resulted in reduced Gag-Pol cis or trans incorporation into Pr55^gag particles, regardless of whether or not Gag cleavage sites within Gag-Pol were blocked.

CONCLUSIONS

Our data suggest that the amount of HIV-1 Gag-Pol or Pol viral incorporation is largely dependent on virus particle production, and that cleavage blocking in the Gag-Pol N-terminal Gag domain does not exert significant impacts on Pol packaging.

Conditional activation of an HIV-1 protease attenuated mutant by a leucine zipper dimerization motif

Mature HIV-1 protease (PR) functions as a dimer. Changes in HIV-1 PR activation can block virus assembly via premature or enhanced Gag cleavage. HIV-1 PR precursor contains N terminal-linked p6*, a possible modulating factor in PR activation. We found that p6* replacement with a leucine zipper (LZ) dimerization motif (creating a DWzPR construct) or an LZ insertion at the PR C-terminus significantly reduced virus yields due to enhanced Gag cleavage, suggesting that an LZ insertion promotes PR activation by facilitating PR dimer formation. However, introducing T26S (a PR activity-attenuated mutation) into DWzPR strongly impaired Gag cleavage, except when the native C-terminal p6* tetrapeptide remained at the LZ/PR junction. LZ insertion at the PR C-terminus still strongly enhanced PR T26S Gag cleavage. Our data suggest that in addition to p6* mutations, a single amino acid substitution within PR can impair PR activation, likely due to conformational changes triggered by the PR precursor.

Severe acute respiratory syndrome coronavirus spike protein counteracts BST2-mediated restriction of virus-like particle release

BST2/tetherin, an interferon‐inducible antiviral factor, can block the cellular release of various enveloped viruses. We previously reported that human coronavirus 229E (HCoV‐229E) infection can alleviate the BST2 tethering of HIV‐1 virions by downregulating cell surface BST2, suggesting that coronaviruses are capable of encoding anti‐BST2 factors. Here we report our new finding that severe acute respiratory syndrome coronavirus (SARS‐CoV) spike (S) glycoprotein, similar to Vpu, is capable of antagonizing the BST2 tethering of SARS‐CoV, HCoV‐229E, and HIV‐1 virus‐like particles via BST2 downregulation. However, unlike Vpu (which downmodulates BST2 by means of proteasomal and lysosomal degradation pathways), BST2 downregulation is apparently mediated by SARS‐CoV S through the lysosomal degradation pathway only. We found that SARS‐CoV S colocalized with both BST2 and reduced cell surface BST2, suggesting an association between SARS‐CoV S and BST2 that targets the lysosomal degradation pathway. According to one recent report, SARS‐CoV ORF7a antagonizes BST2 by interfering with BST2 glycosylation¹. Our data provide support for the proposal that SARS‐CoV and other enveloped viruses are capable of evolving supplementary anti‐BST2 factors in a manner that requires virus replication. Further experiments are required to determine whether the BST2‐mediated restriction of authentic SARS‐CoV virions is alleviated by the SARS‐CoV spike protein.

BST2/tetherin inhibits the release of various enveloped viruses.

SARS‐CoV S antagonizes the BST2 tethering of human coronavirus and HIV‐1 virus‐like particles.

SARS‐CoV S colocalizes with BST2 and reduces cell surface BST2.

SARS‐CoV S downregulates BST2 through lysosomal degradation pathway.

p6gag domain confers cis HIV-1 Gag-Pol assembly and release capability

During virus assembly, HIV-1 Gag-Pol is packaged into virions via interaction with Pr55gag. Studies suggest that Gag-Pol by itself is incapable of virus particle assembly or cell release, perhaps due to the lack of a budding domain in the form of p6gag, which is truncated within Gag-Pol because of a ribosomal frameshift during Gag translation. Additionally (or alternatively), large molecular size may not support Gag-Pol assembly into virus-like particles (VLPs) or release from cells. To test these hypotheses, we constructed Gag-Pol expression vectors retaining and lacking p6gag, and then reduced Gag-Pol molecular size by removing various lengths of the Pol sequence. Results indicate that Gag-Pol constructs retaining p6gag were capable of forming VLPs with a WT HIV-1 particle density. Gag-Pol molecular size reduction via partial removal of the Pol sequence mitigated the Gag-Pol assembly defect to a moderate degree. Our results suggest that the Gag-Pol assembly and budding defects are largely due to a lack of p6gag, but also in part due to size limitation.

Gag-Pol Transframe Domain p6* Is Essential for HIV-1 Protease-Mediated Virus Maturation

HIV-1 protease (PR) is encoded by pol, which is initially translated as a Pr160^gag-pol polyprotein by a ribosomal frameshift event. Within Gag-Pol, truncated p6gag is replaced by a transframe domain (referred to as p6* or p6pol) located directly upstream of PR. p6* has been proposed as playing a role in modulating PR activation. Overlapping reading frames between p6* and p6gag present a challenge to researchers using genetic approaches to studying p6* biological functions. To determine the role of p6* in PR activation without affecting the gag reading frame, we constructed a series of Gag/Gag-Pol expression vectors by duplicating PR with or without p6* between PR pairs, and observed that PR duplication eliminated virus production due to significant Gag cleavage enhancement. This effect was mitigated when p6* was placed between the two PRs. Further, Gag cleavage enhancement was markedly reduced when either one of the two PRs was mutationally inactivated. Additional reduction in Gag cleavage efficiency was noted following the removal of p6* from between the two PRs. The insertion of a NC domain (wild-type or mutant) directly upstream of PR or p6*PR did not significantly improve Gag processing efficiency. With the exception of those containing p6* directly upstream of an active PR, all constructs were either noninfectious or weakly infectious. Our results suggest that (a) p6* is essential for triggering PR activation, (b) p6* has a role in preventing premature virus processing, and (c) the NC domain within Gag-Pol is not a major determinant of PR activation.

SARS-CoV envelope protein palmitoylation or nucleocapid association is not required for promoting virus-like particle production

BACKGROUND

Coronavirus membrane (M) proteins are capable of interacting with nucleocapsid (N) and envelope (E) proteins. Severe acute respiratory syndrome coronavirus (SARS-CoV) M co-expression with either N or E is sufficient for producing virus-like particles (VLPs), although at a lower level compared to M, N and E co-expression. Whether E can release from cells or E/N interaction exists so as to contribute to enhanced VLP production is unknown. It also remains to be determined whether E palmitoylation or disulfide bond formation plays a role in SARS-CoV virus assembly.

RESULTS

SARS-CoV N is released from cells through an association with E protein-containing vesicles. Further analysis suggests that domains involved in E/N interaction are largely located in both carboxyl-terminal regions. Changing all three E cysteine residues to alanines did not exert negative effects on E release, E association with N, or E enhancement of VLP production, suggesting that E palmitoylation modification or disulfide bond formation is not required for SARS-CoV virus assembly. We found that removal of the last E carboxyl-terminal residue markedly affected E release, N association, and VLP incorporation, but did not significantly compromise the contribution of E to efficient VLP production.

CONCLUSIONS

The independence of the SARS-CoV E enhancement effect on VLP production from its viral packaging capacity suggests a distinct SARS-CoV E role in virus assembly.

BST2/CD317 counteracts human coronavirus 229E productive infection by tethering virions at the cell surface

Bone marrow stromal antigen 2 (BST2), an interferon-inducible antiviral factor, has been shown to block the release of various enveloped viruses from cells. It has also been identified as an innate immune system component. Most enveloped viruses subject to BST2 restriction bud at the plasma membrane. Here we report our findings that (a) the production of human coronavirus 229E (HCoV-229E) progeny viruses, whose budding occurs at the ER-Golgi intermediate compartment (ERGIC), markedly decreases in the presence of BST2; and (b) BST2 knockdown expression results in enhanced HCoV-229E virion production. Electron microscopy analyses indicate that HCoV-229E virions are tethered to cell surfaces or intracellular membranes by BST2. Our results suggest that BST2 exerts a broad blocking effect against enveloped virus release, regardless of whether budding occurs at the plasma membrane or intracellular compartments.

Enhancement of nasal absorption of calcitonin loaded in liposomes

Intranasal administration of calcitonin-containing liposomes in rabbits was investigated to evaluate the in vivo calcitonin absorption performance. Plasma calcitonin concentrations and calcium levels were measured and pharmacokinetic parameters were calculated. The bioavailability of calcitonin resulted from the intranasal delivery formulations demonstrated an order of calcitonin-containing positively charged liposomes > calcitonin-containing negatively charged liposomes > calcitonin solution. The significant enhancement of bioavailability of calcitonin for positively charged liposomes may be due to the charge interaction of positively charged liposomes with the negatively charged mucosa surface. Marked accumulation of positively charged liposomes was found on the negatively charged nasal mucosa surface. The retention of positively charged liposomes on the nasal mucosa resulted in an increase of residence time with high local concentration of calcitonin for increase of absorption.

Placement of leucine zipper motifs at the carboxyl terminus of HIV-1 protease significantly reduces virion production

Natural HIV-1 protease (PR) is homodimeric. Some researchers believe that interactions between HIV-1 Gag-Pol molecules trigger the activation of embedded PR (which mediates Gag and Gag-Pol cleavage), and that Gag-Pol assembly domains outside of PR may contribute to PR activation by influencing PR dimer interaction in a Gag-Pol context. To determine if the enhancement of PR dimer interaction facilitates PR activation, we placed single or tandem repeat leucine zippers (LZ) at the PR C-terminus, and looked for a correlation between enhanced Gag processing efficiency and increased Gag-PR-LZ multimerization capacity. We found significant reductions in virus-like particles (VLPs) produced by HIV-1 mutants, with LZ fused to the end of PR as a result of enhanced Gag cleavage efficiency. Since VLP production can be restored to wt levels following PR activity inhibition, this assembly defect is considered PR activity-dependent. We also found a correlation between the LZ enhancement effect on Gag cleavage and enhanced Gag-PR multimerization. The results suggest that PR dimer interactions facilitated by forced Gag-PR multimerization lead to premature Gag cleavage, likely a result of premature PR activation. Our conclusion is that placement of a heterologous dimerization domain downstream of PR enhances PR-mediated Gag cleavage efficiency, implying that structural conformation, rather than the primary sequence outside of PR, is a major determinant of HIV-1 PR activation.

Mutations in the HIV-1 reverse transcriptase tryptophan repeat motif affect virion maturation and Gag-Pol packaging

Our goal was to determine the contribution of HIV-1 reverse transcriptase tryptophan repeat motif residues to virion maturation. With the exception of W402A, we found none of the single substitution mutations exerted major impacts on virus assembly or processing. However, all mutants except for W410A exhibited significant decreases in virus-associated RT, presumably a result of unstable RT mutant degradation. Mutations W398A, W401A and W406A decreased the enhancement effect of efavirenz on PR-mediated Gag processing efficiency, which is in agreement with their destabilizing RT effects. Furthermore, combined double or triple W398, W401 and W406 mutations significantly affected virus processing and Gag-Pol packaging. Further analyses suggest that inefficient PR-mediated Gag cleavage partly accounts for the virion processing defect. Our results support the idea that in addition to playing a role in RT heterodimer stabilization, the RT Trp repeat motif in the Gag-Pol context is also involved in PR activation via Gag-Pol/Gag-Pol interaction.

Efficient in silico assay of inhibitors of hepatitis C Virus RNA-dependent RNA polymerase by structure-based virtual screening and in vitro evaluation

To identify a new protective or therapeutic intervention for hepatitis C virus (HCV) infection, we performed efficient structure-based virtual screening to identify novel inhibitory agents for HCV. To this end, we selected NS5B, an RNA-dependent RNA polymerase (RdRp), as the target for the treatment of HCV infection. To decipher the dockable nature of various RdRp X-ray crystals, we docked the crystal ligand (inhibitor) to the crystal receptor (enzyme). The accuracy of regeneration of the crystal pose indicates the amenability of the RdRp binding pocket for structure-based virtual screening. We also utilized a consensus scoring scheme to reduce false positives, thereby ensuring efficient virtual screening. In this study, each molecule that ranked in the top 1% among all screening molecules gained 1 consensus point in a scoring function. Thus, after virtual screening of 57,177 chemicals from the Maybridge Screening collection, 14 molecules gained 8 points across 11 scoring functions. One of them, an isoxazole, showed significant dose-dependent inhibition of HCV RdRp activity and replication. In this study, we have developed a structure-based virtual screening method using HCV RdRp for efficient identification of novel inhibitors.

Self-assembly of severe acute respiratory syndrome coronavirus membrane protein

Coronavirus membrane (M) protein can form virus-like particles (VLPs) when coexpressed with nucleocapsid (N) or envelope (E) proteins, suggesting a pivotal role for M in virion assembly. Here we demonstrate the self-assembly and release of severe acute respiratory syndrome coronavirus (SARS-CoV) M protein in medium in the form of membrane-enveloped vesicles with densities lower than those of VLPs formed by M plus N. Although efficient N-N interactions require the presence of RNA, we found that M-M interactions were RNA-independent. SARS-CoV M was observed in both the Golgi area and plasma membranes of a variety of cells. Blocking M glycosylation does not appear to significantly affect M plasma membrane labeling intensity, M-containing vesicle release, or VLP formation. Results from a genetic analysis indicate involvement of the third transmembrane domain of M in plasma membrane-targeting signal. Fusion proteins containing M amino-terminal 50 residues encompassing the first transmembrane domain were found to be sufficient for membrane binding, multimerization, and Golgi retention. Surprisingly, we found that fusion proteins lacking all three transmembrane domains were still capable of membrane binding, Golgi retention, and interacting with M. The data suggest that multiple SARS-CoV M regions are involved in M self-assembly and subcellular localization.

Gene Transfer Mediated by Sphingosine/ Dioleoylphosphatidylethanolamine Liposomes in the Presence of Poloxamer 188

A cationic liposome system consisting of sphingosine (SP) and dioleoylphosphatidylethanolamine (DOPE) was developed for in vitro and in vivo gene transfer. A nonionic surface active agent of poloxamer 188 was incorporated in the formulations to stabilize the DNA/liposome complex. Comparison of the results obtained from systems with and without the effect of poloxamer 188 was made to investigate the efficiency of gene expression. In vitro transfection study of the DNA/liposome complex showed that with the effect of poloxamer 188, gene transfer into some cell lines was enhanced. In vivo systemic delivery of the DNA/liposome complex with poloxamer 188 demonstrated gene expression with improved luciferase activity in all major organs including lung, spleen, heart, liver, and kidney. High level transgene activity was found in lung and spleen with prolonged gene expression. This was attributed to poloxamer 188 that stabilized the liposome system and produced homogeneous DNA/liposome complex for enhancement of gene delivery.

HIV-1 matrix protein repositioning in nucleocapsid region fails to confer virus-like particle assembly

The HIV-1 matrix (MA) protein is similar to nucleocapsid (NC) proteins in its propensity for self-interaction and association with RNA. Here we report on our finding that replacing MA with NC results in the production of wild type (wt)-level RNA and virus-like particles (VLPs). In contrast, constructs containing MA as a substitute for NC are markedly defective in VLP production and form virions with lower densities than wt, even though their RNA content is over 50% that of wt level. We also noted that a ΔMN mutant lacking both MA and NC produces a relatively higher amount of VLPs than those in which MA was substituted for NC. Although ΔMN contains approximately 30% the RNA of wt, it still exhibits virion densities equal (or very similar) to those of wt. The data suggest that neither NC nor RNA are major virion density determinants. Furthermore, we noted that NC(ZIP)—a NC replacement with a leucine zipper dimerization motif—produces VLPs as efficiently as wt. However, the markedly reduced assembly efficiency of NC(ZIP) is associated with the formation of VLPs with densities slightly lower than those of wt following MA removal, suggesting that (a) MA is required to help the inserted leucine zipper motif perform efficient Gag multimerization, and (b) MA plays a role in the virus assembly process.

Mutations in capsid major homology region affect assembly and membrane affinity of HIV-1 Gag

We introduced mutations into the HIV-1 major homology region (MHR; capsids 153-172) and adjacent C-terminal region to analyze their effects on virus-like particle (VLP) assembly, membrane affinity, and the multimerization of the Gag structural protein. Results indicate that alanine substitutions at K158, F168 or E175 significantly diminished VLP production. All assembly-defective Gag mutants had markedly reduced membrane-binding capacities, but results from a velocity sedimentation analysis suggest that most of the membrane-bound Gag proteins were present, primarily in a higher-order multimerized form. The membrane-binding capacity of the K158A, F168A, and E175A Gag proteins increased sharply upon removal of the MA globular domain. While demonstrating improved multimerization capability, the two MA-deleted versions of F168A and E175A did not show marked improvement in VLP production, presumably due to a defect in association with the raft-like membrane domain. However, K158A bound to detergent-resistant raft-like membrane; this was accompanied by noticeably improved VLP production following MA removal. Our results suggest that the HIV-1 MHR and adjacent downstream region facilitate multimerization and tight Gag packing. Enhanced Gag multimerization may help expose the membrane-binding domain and thus improve Gag membrane binding, thereby promoting Gag multimerization into higher-order assembly products.

Incorporation of human immunodeficiency virus type 1 reverse transcriptase into virus-like particles

We demonstrate that a genetically engineered human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) composed mainly of p66 or p51 subunits can be incorporated into virus-like particles (VLPs) when coexpressed with HIV-1 Pr55(gag). VLP-associated RT exhibited a detergent-resistant association with immature cores during sucrose gradient equilibrium centrifugation, suggesting that RT is incorporated into VLPs. However, RT that retains downstream integrase (IN) is severely inhibited in terms of incorporation into VLPs. Results from immunofluorescence tests reveal that RT-IN is primarily localized at the perinuclear area and exhibits poor colocalization with Gag. IN removal leads to a redistribution of RT throughout the cytoplasm and improved RT incorporation into VLPs. Similar results were observed for RT-IN in which alanine was substituted for 186-Lys-Arg-Lys-188 residues of the IN putative nuclear localization signal, suggesting that IN karyophilic properties may partly account for the inhibitory effect of IN on RT incorporation. Although the membrane-binding capacity of RT was markedly reduced compared to that of wild-type Gag or Gag-Pol, the correlation of membrane-binding ability with particle incorporation efficiency was incomplete. Furthermore, we observed that membrane-binding-defective myristylation-minus RT can be packaged into VLPs at the same level as its normal myristylated counterpart. This suggests that the incorporation of RT into VLPs is independent of membrane affinity but very dependent on RT-Gag interaction. Results from a genetic analysis suggest that the Gag-interacting regions of RT mainly reside in the thumb subdomain and that the RT-binding domains of Gag are located in the matrix (MA) and p6 regions.

Treatment of focal cerebral ischemia with liposomal nerve growth factor

Liposomal nerve growth factor (NGF) was used for the treatment of focal cerebral ischemia in a rat model. Positive charge inducing agents of sphingosine (SP) and stearylamine (S) were formulated in the liposomal NGF. Dose-response of intraventricular injection of liposomal NGF showed significant reduction in infarct volume at the dose of 5 and 10 microg/rat of NGF. The liposomal NGF formulated with SP or S demonstrated similar results in the reduction of total infarct volume in rats. When we increased the molar ratio of SP and S from 0.15 to 0.3, the infarct volume from rats showed a similar value as that of the control treated with NGF solution. Liposomal NGF was given prior to the development of ischemia. We found that NGF was effective in prevention of neuronal death. The NGF concentrations in brain for liposomal NGF were maintained in a level significantly higher than those for NGF solution. This was attributed to the positively charged liposomal NGF bound effectively in brain ventricle and caused longer retention time than free NGF for localization in brain. Therefore, the effect of liposomal NGF on reduction of infarct volume was significant. We assumed that the transportation of NGF might go through the cerebrospinal fluid pathway throughout the ventricular system and subarachnoid system to cerebral cortex to produce a therapeutic effect on ischemia.

A new cell-based assay for measuring the forward mutation rate of HIV-1

Over 20 years into the ever-worsening AIDS pandemic, genetic variation remains the greatest obstacle for treating and preventing HIV-1 infection. Mutation rate assays for HIV-1 have been reported; however, none measure directly the forward mutation rate during replication of the virus in cell culture while still retaining the ability to propagate and further study mutant proviruses. Therefore, the objective of the current study was to develop such a phenotypic cell-based assay for measuring the forward mutation rate of HIV-1. Conventional recombinant DNA techniques and polymerase chain reaction were used to create a replication defective HIV-1 vector, pNL4-3Delta+cass, which is based on the NL4-3 strain and contains the thymidine kinase gene from human herpes virus type 1 as the mutational target. A series of transfection and infection steps were used to introduce the vector into 143B cells, which are negative for thymidine kinase function, and produce vector virus for a single cycle of replication. Viral titers were measured by counting the number of drug resistant colonies on the assay plates, and forward mutation rates were calculated from the viral titers. Mutant proviruses were sequenced to determine the types of genetic alterations that occurred. The average forward mutation rate for HIV-1 was 2.2 x 10(-5)mutations/base/cycle. The majority of mutations were base substitutions, including high frequencies of C-->U and G-->A transitions. Single adenosine insertions were also observed frequently. The new assay is economical and provides a direct measurement of the mutation rate during a single cycle of viral replication. Target cells containing mutant proviruses survive the drug selection process and may be propagated for further analysis. The new assay is novel and has many advantages over previous mutation rate assays and thus will be very useful in future studies on genetic variation of HIV-1.

Stability of desmopressin loaded in liposomes

Desmopressin-containing liposome formulations have been developed for intranasal administration previously. Positively charged liposomes were found to be an efficient delivery system for desmopressin. In this study, stability of the loaded desmopressin in positively charged liposomes was further investigated. Comparison of the stability of desmopressin in solution and liposomes was made. Degradation of desmopressin was shown to follow a pseudo-first-order reaction. Degradation of desmopressin in both solution and liposomes demonstrated the same kinetic behavior and exhibited no significant difference in half-lives. Similar v-shape pH-rate profile was found for desmopressin degradation in solution and liposomes. At pH 4.0, the inflection point of the v-shape pH-rate curve, the reaction rate of desmopressin was lowest and the stability was greatest. The stability of lipid ingredients of dioleoylphosphatidylcholine (DOPC), cholesterol (C), and stearylamine (S) in the liposome dispersion at pH 4.0 was studied. Results demonstrated that DOPC, C, and S were relatively stable in the liposome structure when formulated with desmopressin. The degradation of desmopressin in solution and liposomes in the presence of alpha-chymotrypsin was investigated. A longer half-life for desmopressin in liposomes than in solution was observed. It was suggested that desmopressin was protected by the liposomes against alpha-chymotrypsin digestion.

Bovine ephemeral fever in Taiwan

Bovine ephemeral fever (BEF) is a vector-borne disease of cattle, spanning tropical and subtropical zones of Asia, Australia, and Africa, caused by Ephemerovirus of the Rhabdoviridae. Taiwan has had 3 BEF epizootics, occurring in 1989, 1996, and 1999, since the vaccination regimen was initiated in 1984, given once a year in the spring with a single-dose formaldehyde-inactivated vaccine using the 1983 isolate as the seed virus. This study evaluated the 1999 population immunity against BEF virus in Taiwanese dairy cows with a neutralization test and whether the recent BEF virus isolates have mutated significantly from the vaccine virus. In March 1999, before vaccination, 94% of the animals studied were already seropositive, suggestive of an endemic or persistent infection from the previous year. By June 1999, when 51% of herds had been vaccinated, the antibody level rose, and by September 1999, the serum-neutralizing antibody (SNA) level fell to a minimum, preceding the outbreak of BEF in October 1999, during which the antibody levels of vaccinated cows continued to decline while those of unvaccinated cows rose sharply. The results suggest that, in 1999, vaccine-induced immunity was partially protective against BEE Because the current single-dose vaccination regimen resulted in minimal population immunity by September, a booster vaccination given in late summer may be advisable for future disease control. Analysis of the glycoprotein gene of Taiwanese isolates between 1983 and 1999 showed a 97.4-99.6% homology, with an alteration of 4 amino acids in antigenic sites G1, G3b, and G3c. Phylogenetic analysis of Taiwanese isolates revealed at least 2 distinct clusters: the 1983-1989 isolates and the 1996-1999 isolates. Both were distinct from 2 Japanese strains and the Australian BB7721 strain. Thus, at least 2 distinct BEF viruses, which had diverged before 1983, existed in Taiwanese dairy cows.

Preparation of desmopressin-containing liposomes for intranasal delivery

The loading and leakage characteristics of the desmopressin-containing liposomes and the effect of liposomes on the nasal mucosa permeation and antidiuresis of desmopressin were investigated. Higher loading efficiency of desmopressin for positively charged liposomes than negatively charged liposomes was obtained, and neutral liposomes resulted in a similar loading efficiency as that of positively charged liposomes. Greater leakage of desmopressin from negatively charged liposomes than from positively charged and neutral liposomes was shown. The increase of permeability of desmopressin through the nasal mucosa indicated positively charged liposomes>negatively charged liposomes>solution. It was suggested that the enhanced contact time of positively charged liposomes with negatively charged nasal mucosa led to a high local desmopressin concentration on the penetration site to promote an effective penetration of desmopressin through the nasal mucosa. The desmopressin antidiuresis result after intranasal administration was in good agreement with the permeability result in the order of positively charged liposomes>negatively charged liposomes>solution. One of the mechanisms for the explanation of the best result on the enhancement of antidiuresis for positively charged liposomes may be the bioadhesive effect of the liposomes on the negatively charged nasal mucosa.

Acyclovir-containing liposomes for potential ocular delivery. Corneal penetration and absorption

The in vitro corneal penetration and in vivo corneal absorption of acyclovir from an acyclovir-containing liposome system were investigated. Results of in vitro corneal penetration demonstrated that positively charged liposomes resulted in a penetration rate lower than those of negatively charged liposomes and free acyclovir in solution. An in vivo study indicated that the extent of acyclovir absorption from positively charged liposomes was higher that those from negatively charged liposomes and free acyclovir. The acyclovir concentration in the cornea after administration of positively charged liposomes showed that an acyclovir deposition in the cornea was greater than those of negatively charged liposomes and free acyclovir. From morphological observation of the cornea surface treated with liposomes, it was suggested that positively charged liposomes formed a completely coated layer on the cornea surface. These liposomes would bind intimately on the cornea surface, leading to an increase of residence time. Therefore, positively charged liposomes resulted in an increase of acyclovir (ACV) absorption.

Induction of thymocyte apoptosis in mice by Yersinia enterocolitica products

In-vivo administration of the culture supernates from Yersinia enterocolitica resulted in thymus atrophy in C3H/HeJ mice, known to be lipopolysaccharide (LPS)-nonresponders. The thymocytes underwent apoptosis as characterised by fragmented DNA ladders on agarose gel electrophoresis, a cell death detection ELISA and a morphological study by the TUNEL reaction. As a control, LPS treatment did not induce thymocyte apoptosis in C3H/HeJ mice. Flow cytometric analysis indicated that thymus atrophy was due predominantly to the deletion of CD4+ CD8+ T cells. When cells were undergoing apoptosis, an elevation in the percentage of T-cell receptor (TCR)-alphabeta(high) cells was observed at 24 h, which was correlated with the increase in the percentages of cells expressing high levels of the Vbeta6 and Vbeta8 TCR. Gel electrophoretic analysis demonstrated the presence of protein bands with mol.wts ranging from 17 to 65 kDa in Y. enterocolitica culture supernates.

Acute and subacute toxicity study of water-soluble polyalkylsulfonated C60 in rats

Polyalkylsulfonated C60, or FC4S, a highly water-soluble caged fullerene derivative, is believed to be a free radical remover or an antioxidant in biological systems. A 50 mg/ml aqueous solution was prepared as a master solution and administered to female Sprague-Dawley CD(Crl:CD(SD)BR) rats in a single-dose acute toxicity study or a 12-day subacute toxicity study where rats were given the solution daily. In a study of the median lethal dose (LD50), no rats died after oral administration, and thus FC4S was considered to be nontoxic if administered orally. In an LD50 intraperitoneal injection study, rats died within 30 hr after injection; the LD50 was determined to be approximately 600 mg per kilogram of body weight. Rats injected with the compound intraperitoneally or intravenously immediately eliminated the compound through the kidney; the kidney appeared to be the primary target organ. The compound induced a distinct lysosome-overload nephrosis, a phagolysosomal nephropathy characterized by a tinctorial difference between the outer cortex and the inner cortex and the medulla. The affected outer cortex showed a diffuse degeneration, with the presence of numerous large vacuoles and cytoplasmic aggregates in the tubular epithelium. The phagolysosomal nephropathy was detected in rats after acute exposure as well as in the surviving rats following 1 intraperitoneal injection of 500 mg/kg or intravenous injection of 100 mg/kg. Ultrastructural investigation revealed numerous membranous conglomerates characteristic of phagolysosomal and/or lysosomal inclusions in the cytoplasm of the renal tubular epithelium. These conglomerates were confined to the vacuole, electron-dense, and unevenly stained. They varied in size and shape and were fused or aggregated. Occasional phagolysosomes were also observed in the endothelial cells of the peritubular plexus. A preliminary study of microsomal enzyme activity analysis revealed a suppression effect of liver cytochrome P-450-dependent monooxygenase activities, including cytochrome P-450, cytochrome b5, and benzo(a)pyrene hydroxylase, but an increased level of kidney cytochrome P-450-dependent monooxygenase activities, including NADPH-cytochrome P-450 reductase. The significance of these enzyme alterations was not well determined. Further study is needed to clarify the correlation between the alterations of microsomal enzyme activity and the nephropathy of lysosomal overload-induced changes. These changes may serve as a biological marker in toxicity screening tests for this class of compound.

Retrograde lymphatic spread: a likely route for metastatic ovarian cancers of gastrointestinal origin

In order to outline the pathways of gastrointestinal malignancies metastasizing to the ovaries, we reviewed 103 cases of metastatic ovarian tumors, and also performed para-aortic lymph node sampling on 11 patients at operation for metastatic ovarian tumors. Of the 103 patients, 74% (26/35) with gastric cancer and 67% (45/67) with colorectal cancer had lymph node metastasis at or before the diagnosis of ovarian tumor. Intraperitoneal metastases presented in 49 and 42% of patients with gastric and with colorectal cancers, respectively. Twenty-three percent of gastric cancer patients and 25% of colorectal cancer patients presented with both lymph node and intraperitoneal metastases. The ovary was the first or among the early metastatic organs diagnosed in 51 of the 53 patients with metachronous ovarian metastases. Only 4 patients with colorectal cancer and none with gastric cancer showed parenchymal organ metastases. These 4 patients also showed intraperitoneal lesions, and 3 of these 4 patients had node metastasis. Among the 11 patients who underwent prospective para-aortic lymph node sampling during operation for the ovarian tumors, only 1 had enlarged para-aortic nodes depicted by computed tomography, 2 had grossly enlarged (>/=1.5 cm) para-aortic lymph nodes noted at surgery, and 6 of the 7 patients with gastric cancer and all 3 with colorectal cancer had metastatic nodes histologically. Among the 58 nodes taken from these patients, 67% showed metastatic foci. We concluded that lymph node metastasis is frequently seen in patients with metastatic ovarian tumors of gastrointestinal origin, and hypothesized that retrograde lymphatic spread is a likely route for the metastases.

Phosphorylation stimulates the cooperative DNA-binding properties of the transcription factor OmpR

The two-component regulatory proteins OmpR and EnvZ of Escherichia coli K-12 regulate expression of the major outer membrane porin protein, OmpF. OmpR is a DNA-binding protein that is involved in both the positive and negative control of ompF transcription. EnvZ is a histidine kinase that phosphorylates OmpR in response to environmental signals. We used DNA migration retardation analysis to examine the interactions of OmpR and the phosphorylated form of OmpR (OmpR-P) with the regulatory region immediately upstream of the ompF promoter. Our results indicate that the binding of OmpR to this regulatory region is cooperative and that phosphorylation significantly stimulates these cooperative interactions. Moreover, although phosphorylation increases the intrinsic binding of OmpR to a single OmpR-binding site, the primary role of phosphorylation in ompF regulation is to facilitate cooperative interactions between OmpR molecules bound at adjacent sites. Based on these results, we propose a model to explain how the phosphorylation of OmpR could stimulate the occupancy of specific sites in the ompF regulatory region, thereby resulting in the activation or repression of ompF transcription under the appropriate environmental conditions.

Identification of the bases in the ompF regulatory region, which interact with the transcription factor OmpR

Expression of the outer membrane protein OmpF of Escherichia coli K-12 is influenced by a variety of environmental signals. Most of the signals are thought to regulate OmpF expression at the level of transcription initiation. A key element of this regulation is the interaction between the transcriptional factor OmpR and the cis-acting regulatory region of ompF. In this study, we used a combination of DNase I, dimethyl sulfate and hydroxyl radical footprinting analysis and DNA migration retardation assays to identify the bases within the ompF regulatory region that are in contact with OmpR. Our results indicate that the -107 to -39 region of ompF contains three individual binding sites and that a single OmpR-binding site is capable of interacting with two OmpR molecules. We also establish that a single OmpR-binding site is composed of two half-sites and that both half-sites are required for the formation of stable OmpR/DNA complexes. Comparisons of the sequences protected by OmpR indicate that an OmpR-binding site spans approximately 18 bp and has two highly conserved G/C base-pairs that are separated by three nucleotides. Although the three OmpR-binding sites we identified exhibit limited sequence similarity, this may reflect the fact that two of the sites are incapable of binding OmpR independently and can bind OmpR only if adjacent to another OmpR-binding site. Finally, our DNA migration retardation assays suggest that phosphorylation stimulates the cooperative interactions between OmpR molecules bound at neighboring sites. Therefore, this study provides a detailed understanding of how OmpR interacts with its binding sites immediately upstream of ompF and serves as a foundation for studying how phosphorylation of OmpR results in the regulation of ompF expression in response to environmental signals.

Sepsis-induced apoptosis of the thymocytes in mice

Intraperitoneal injection of Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa) induces thymic atrophy in mice. The thymus weight, cell number, and viability began to decrease at 3 h, and reached their lowest level at 72 h. The thymocyte death was associated with DNA fragmentation of approximately 200 base pairs in ladder form. The kinetic study on histopathology revealed the process of thymocyte death and thymic atrophy. Flow-cytometric analysis showed that CD4+CD8+ thymocytes decreased predominantly. LPS caused thymocyte apoptosis, but only in LPS-responder mice, unlike Gram-negative bacteria that induced apoptosis in both LPS-responder (C3H/HeN) and LPS-nonresponder (C3H/HeJ). Gram-positive bacteria Streptococcus pneumoniae also caused apoptosis in LPS-nonresponder (C3H/HeJ) and LPS-responder mice (B6). The kinetics of serum TNF-alpha production after Gram-negative or Gram-positive bacteria injection was slightly different. E. coli induced serum TNF-alpha peak at 1 h in B6 mice, whereas S. pneumoniae induced a peak at 6 h in C3H/HeJ and at 9 h in B6 mice. Similarly, S. pneumoniae induced thymocyte apoptosis around 9 to 12 h, which was 6 to 9 h later than that observed with E. coli in B6 mice. Anti-TNF-alpha Ab completely blocked the E. coli-induced thymocyte apoptosis, but was only partially inhibitory on the S. pneumoniae-induced thymocyte apoptosis. Furthermore, thymocyte apoptosis induced by E. coli was inhibited by cycloheximide or actinomycin D. These data indicate that both Gram-negative and Gram-positive bacteria could induce thymus atrophy via apoptosis, and that TNF-alpha is a common denominator released and might be responsible for the thymocyte apoptosis.

Sepsis-induced apoptosis of the thymocytes in mice

Intraperitoneal injection of Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa) induces thymic atrophy in mice. The thymus weight, cell number, and viability began to decrease at 3 h, and reached their lowest level at 72 h. The thymocyte death was associated with DNA fragmentation of approximately 200 base pairs in ladder form. The kinetic study on histopathology revealed the process of thymocyte death and thymic atrophy. Flow-cytometric analysis showed that CD4+CD8+ thymocytes decreased predominantly. LPS caused thymocyte apoptosis, but only in LPS-responder mice, unlike Gram-negative bacteria that induced apoptosis in both LPS-responder (C3H/HeN) and LPS-nonresponder (C3H/HeJ). Gram-positive bacteria Streptococcus pneumoniae also caused apoptosis in LPS-nonresponder (C3H/HeJ) and LPS-responder mice (B6). The kinetics of serum TNF-alpha production after Gram-negative or Gram-positive bacteria injection was slightly different. E. coli induced serum TNF-alpha peak at 1 h in B6 mice, whereas S. pneumoniae induced a peak at 6 h in C3H/HeJ and at 9 h in B6 mice. Similarly, S. pneumoniae induced thymocyte apoptosis around 9 to 12 h, which was 6 to 9 h later than that observed with E. coli in B6 mice. Anti-TNF-alpha Ab completely blocked the E. coli-induced thymocyte apoptosis, but was only partially inhibitory on the S. pneumoniae-induced thymocyte apoptosis. Furthermore, thymocyte apoptosis induced by E. coli was inhibited by cycloheximide or actinomycin D. These data indicate that both Gram-negative and Gram-positive bacteria could induce thymus atrophy via apoptosis, and that TNF-alpha is a common denominator released and might be responsible for the thymocyte apoptosis.

A distant upstream site involved in the negative regulation of the Escherichia coli ompF gene

The two-component regulatory system, OmpR-EnvZ, of Escherichia coli K-12 regulates the expression of the major outer membrane porin protein, OmpF. OmpR is a DNA-binding protein which acts as both an activator and a repressor to control ompF transcription. In this article, we describe a new OmpR-binding site that is located between 384 to 351 bp upstream from the ompF start point of transcription. Inactivation of this site by insertion of a 22-bp fragment prevents the repression of ompF expression conferred by the dominant negative mutation, envZ473. On the basis of the location of this binding site, the presence of bent DNA in the ompF regulatory region (T. Mizuno, Gene 54:57-64, 1987), and the fact that mutations altering integration host factor result in constitutive ompF expression (P. Tsui, V. Helu, and M. Freundlich, J. Bacteriol. 170:4950-4953, 1988), we propose that the negative regulation of ompF involves a DNA loop structure.

Effects of lysine-sensitive aspartokinase III on lysine biosynthesis in Escherichia coli K-12

A promoterless lysC gene, coding for Escherichia coli aspartokinase III (AKase III), has been cloned by phenotypic complementation using plasmid pUC19 as the vector. The hybrid plasmid obtained, pUC19AK3, preserved the ribosome binding site and transcriptional termination signal of the gene but with a lac promoter. E. coli strains containing the recombinant plasmid had high levels of AKase III activity. AKase III activity from expressing strains was inhibited by lysine, leucine, and S-(2-aminoethyl)-L-cysteine (AEC) but not by threonine and methionine. The overexpressed AKase III enzyme had a molecular weight of about 50 kD from SDS-polyacrylamide gel electrophoresis. N-terminal amino acid sequence analysis confirmed that the product from the hybrid plasmid was identical to native AKase III rather than a fusion protein. Moreover, overexpression of AKase III significantly increased lysine excretion in the plasmid-harboring E. coli strain DH1. This increase in the level of AKase III activity also affected other metabolites than lysine. Addition of aspartate to the medium brought about significant increases in lysine excretion. A maximum increase (about 8-fold) in lysine accumulation was observed 45 minutes after incubation in minimal medium containing 0.2% aspartate as compared to aspartate-free medium.

Classification, pathogenicity, and drug susceptibility of hemolytic gram-negative bacteria isolated from sick or dead chickens

Fifteen hemolytic gram-negative bacteria were isolated from the respiratory tracts of sick birds suffering from a long-lasting respiratory syndrome or from the bone marrow of dead birds distributed in the southern part of Taiwan. These were classified as Pseudomonas aeruginosa (10 isolates), Pseudomonas fluorescens (2 isolates), Pseudomonas stutzeri (1 isolate), Pasteurella haemolytica (1 isolate), and Proteus morganii (1 isolate). Each isolate was inoculated intraperitoneally into one group of ten 4-week-old male white leghorn chickens. Mortality and lesions were scored daily for 1 week. Three of the 10 isolates of Pseudomonas aeruginosa caused 100% mortality. Six other isolates of Pseudomonas aeruginosa and the one isolate of Proteus morganii caused 50% mortality. The remaining isolates induced less than 30% mortality. The sole nonpathogenic sample was one isolate of Pseudomonas fluorescens. When therapeutic levels of 22 antibiotics or sulfa drugs were evaluated for their inhibitory activity against the 15 isolates, the most effective were apramycin (15/15), gentamicin (15/15), spectinomycin (13/15), oxytetracycline (8/15), and sulfachloropyrazine (7/15). The least effective were ampicillin, cloxacillin, and tiamulin, which were not effective against any of the isolates. The 14 other drugs were of very low (> 4/15) effectiveness. Most of the isolates studied were virulent for chickens and very resistant to currently used drugs.

Cancer of the colon during pregnancy: report of a case and review of the literature

A case of adenocarcinoma of the sigmoid colon during pregnancy is reported. The patient presented with anemia and a painless mass over the left abdomen without gastrointestinal discomfort, making this case different from 25 previously reported cases of colon carcinoma above the peritoneal reflection associated with pregnancy.

A study on the ecological habit of Armigeres subalbatus in Dawa area of the Mengshan Mountain in Shandong Province

Armigeres subalbatus (A.s.) was reported in Shandong Province for the first time in 1965 and found in five counties of south Shandong including Pingyi, Linyi etc. in 1986. In Dawa area of the Mengshan mountain A.s. alults could be found in the first ten days of May, which increased in number in July, and become the dominant species in mosquito colonies in Aug. and Sept., then decreased gradually in number in Oct. and disappeared in Nov. There were two peaks of activity and blood-sucking behavior during the 24 hours of a day, one at dusk and the other at dawn. When the temperature dropped to 16 degrees C and below in the last ten days of Oct., the wigglers began their diapause period. The survival ratio reached 90.5% after 12 h freezing at -5 degrees C and none survived after 60 hours freezing. When the temperature rose to 17 degrees C and above the over-winterting larvae developed into adults, which could suck blood only at the temperature above 17.5 degrees C.

In vitro comparison of the activity of various antifungal drugs against new yeast isolates causing thrush in poultry

Of 44 representative isolates of yeast isolated from the poultry upper digestive tract from 40 clinical thrush cases in Taiwan during 1985-87, 39 (89%) isolates were classified as Candida albicans, and 5 (11%) were classified as Torulopsis pintolopesii. Fifteen commercial antifungal drugs, incorporated individually in Sabouraud's dextrose agar by serial twofold dilutions, were tested for their inhibitory effect against the 44 isolates. The MIC50 of these drugs in increasing order was less than or equal to 2 ppm GV-11, 6 ppm gentian violet, less than 16 ppm amphotericin B, 16 ppm hyamine 1622, 25 ppm econazole, 35 ppm chlorohydroxyquinoline, 40 ppm nystatin, 64 ppm miconazole, 747 ppm malachite green, 1550 ppm benzoic acid, 1536 ppm copper sulfate, 3144 ppm Monoprop, 4951 ppm Mold Zap, greater than 16,384 ppm propionic acid, and greater than 16,384 ppm sodium propionate.

An antigen-specific hypersensitivity which does not fit into traditional classification of hypersensitivity

A unique type of Ag-specific hypersensitivity was induced by challenging the Ag-sensitized mice at the ear. It was elicited within 1 h after the Ag challenge, and thus was distinct from either the delayed-type hypersensitivity (DTH) which developed in 24 h or the immune complex-mediated hypersensitivity which evolved in 4 to 6 h. This hypersensitivity was referred to as early-type hypersensitivity (ETH). The time required for these types of hypersensitivity to develop after immunization was also different; DTH required 4 to 6 days, ETH 9 to 11 days, whereas plasma protein-induced immune complex-mediated hypersensitivity needed 18 to 21 days. The ETH could be induced by a smaller amount of Ag than DTH, and unlike DTH could be transferred by either immune sera or T cell-derived culture factor which was small m.w. Although the ETH developed later than DTH after sensitization, it lasted longer once developed and the pattern of response was inversely related to DTH. Furthermore, the denatured hepatitis B surface Ag induced DTH but not ETH, in contrast to native hepatitis B surface Ag that induced both, suggesting that the epitopes recognized by TETH cells were distinct from those recognized by TDTH cells. The ETH could be induced by most Ag tested including poly(Glu60Ala10Tyr10, L-lactic dehydrogenase, insulin, chicken egg white lysozyme, polymerized human serum albumin, horse gamma-globulin, transferrin, fibrinogen, and plasminogen, but not by purified protein derivative. Because poly(Glu60Ala10Tyr10, L-lactic dehydrogenase, egg white lysozyme and insulin were under the Ir gene control and the inducibility of ETH was Ag dependent and was closely correlated with that of DTH, the expression of ETH also must be regulated by Ir gene. The histopathologic changes in ETH consisted of capillary congestion and edema. The vasopermeability was increased and there was the leakage of plasma proteins into the tissue. Based on these data, we concluded that the ETH reported in this study was a novel type of Ag-specific hypersensitivity.

An antigen-specific hypersensitivity which does not fit into traditional classification of hypersensitivity

A unique type of Ag-specific hypersensitivity was induced by challenging the Ag-sensitized mice at the ear. It was elicited within 1 h after the Ag challenge, and thus was distinct from either the delayed-type hypersensitivity (DTH) which developed in 24 h or the immune complex-mediated hypersensitivity which evolved in 4 to 6 h. This hypersensitivity was referred to as early-type hypersensitivity (ETH). The time required for these types of hypersensitivity to develop after immunization was also different; DTH required 4 to 6 days, ETH 9 to 11 days, whereas plasma protein-induced immune complex-mediated hypersensitivity needed 18 to 21 days. The ETH could be induced by a smaller amount of Ag than DTH, and unlike DTH could be transferred by either immune sera or T cell-derived culture factor which was small m.w. Although the ETH developed later than DTH after sensitization, it lasted longer once developed and the pattern of response was inversely related to DTH. Furthermore, the denatured hepatitis B surface Ag induced DTH but not ETH, in contrast to native hepatitis B surface Ag that induced both, suggesting that the epitopes recognized by TETH cells were distinct from those recognized by TDTH cells. The ETH could be induced by most Ag tested including poly(Glu60Ala10Tyr10, L-lactic dehydrogenase, insulin, chicken egg white lysozyme, polymerized human serum albumin, horse gamma-globulin, transferrin, fibrinogen, and plasminogen, but not by purified protein derivative. Because poly(Glu60Ala10Tyr10, L-lactic dehydrogenase, egg white lysozyme and insulin were under the Ir gene control and the inducibility of ETH was Ag dependent and was closely correlated with that of DTH, the expression of ETH also must be regulated by Ir gene. The histopathologic changes in ETH consisted of capillary congestion and edema. The vasopermeability was increased and there was the leakage of plasma proteins into the tissue. Based on these data, we concluded that the ETH reported in this study was a novel type of Ag-specific hypersensitivity.

[Teratogenicity study on bromperidol in rats]

A teratogenicity study on bromperidol, a neuroleptic, was carried out in Wistar-Imamichi rats. Bromperidol was administered orally at the dose levels of 0.2, 1.5 and 10.0 mg/kg/day for 11 days from day 7 to day 17 of gestation. About two-thirds of pregnant females in each group were sacrificed on day 21 of gestation, and their fetuses were examined. The remaining dams were allowed to litter naturally, and the post-natal development of the offspring was observed. Treatment of bromperidol caused sedation of pregnant females in 1.5 and 10.0 mg/kg groups with concomitant decrease in body weight and in food and water intake in dose-dependent manner. Effect of bromperidol treatment on F1 generation was observed mainly in animals of 10.0 mg/kg group, suggesting overall growth retardation such as decrease in live fetal weight, retarded ossification of metacarpals and metatarsals, a slight decrease in day 1 viability index, a marginal delay in eyelid opening, reduction in growth rate and decrease in organ weight. No treatment-related external and internal abnormalities were observed in fetuses (F1), and no apparent effect on behavior, learning ability and reproductive function of offspring (F1) was found.

Fine pathology of mouse spinal cord infected with the Tyzzer organism

After intraspinal inoculation in mice, Tyzzer organisms were shown to grow within neurons resulting in degeneration and destruction of the host cells. Intraneuronally parasitising organisms were located within the cytoplasmic matrices or nuclear chromatin granules, and host cell organelles were disarranged or decreased in number seemingly by movement of bacterial peritrichous flagella. Axonal as well as myelin degeneration occurred in the white matter, and demyelination seemed to be in consequence of the axon damage due to intraxonal growth of organisms. Some organisms were present within cytoplasmic matrices of oligodendroglia cells and also within phagosomes of macrophages without active intracellular growth.