Modification of seed oil content and acyl composition in the brassicaceae by expression of a yeast sn-2 acyltransferase gene

A putative yeast sn-2 acyltransferase gene (SLC1-1), reportedly a variant acyltransferase that suppresses a genetic defect in sphingolipid long-chain base biosynthesis, has been expressed in a yeast SLC deletion strain. The SLC1-1 gene product was shown in vitro to encode an sn-2 acyltransferase capable of acylating sn-1 oleoyl-lysophosphatidic acid, using a range of acyl-CoA thioesters, including 18:1-, 22:1-, and 24:0-CoAs. The SLC1-1 gene was introduced into Arabidopsis and a high erucic acid-containing Brassica napus cv Hero under the control of a constitutive (tandem cauliflower mosaic virus 35S) promoter. The resulting transgenic plants showed substantial increases of 8 to 48% in seed oil content (expressed on the basis of seed dry weight) and increases in both overall proportions and amounts of very-long-chain fatty acids in seed triacylglycerols (TAGs). Furthermore, the proportion of very-long-chain fatty acids found at the sn-2 position of TAGs was increased, and homogenates prepared from developing seeds of transformed plants exhibited elevated lysophosphatidic acid acyltransferase (EC 2.3.1.51) activity. Thus, the yeast sn-2 acyltransferase has been shown to encode a protein that can exhibit lysophosphatidic acid acyltransferase activity and that can be used to change total fatty acid content and composition as well as to alter the stereospecific acyl distribution of fatty acids in seed TAGs.

Prolactin regulation of mitochondrial aspartate aminotransferase and protein kinase C in human prostate cancer cells

Citrate production is a major physiological function of the prostate that is regulated by testosterone and prolactin. Mitochondrial aspartate aminotransferase (mAAT) is a key enzyme in the metabolic pathway of prostate citrate production. In addition, prolactin stimulates expression of mAAT in the rat lateral prostate. In this report we establish the role of prolactin in the regulation of mAAT in two prostate cancer cell lines, LNCaP and PC-3. LNCaP cells respond to hormonal stimulation with increased secretion of prostate specific products. PC-3 cells, on the other hand, are testosterone independent and apparently do not respond to other growth factors either. Results showed that both LNCaP and PC-3 cells responded to prolactin with increased mAAT activity and an increased steady state level of mAAT mRNA. Prolactin also increased protein kinase C (PKC) activity in both these cell lines. Treatment of LNCaP and PC-3 cells with the phorbol ester 12-O-tetradecanoylphorbol (TPA) caused the same effect on mAAT activity and mRNA level as prolactin. The results suggest that the diacylglycerol-PKC signal transduction system mediates the prolactin effect on mAAT. In addition, these results also show that the prolactin effect on mAAT is independent of androgens since PC-3 cells reportedly lack androgen receptor expression. Thus, these results provide evidence that prolactin is a physiological regulator of prostate function in human as well as rat prostate. In addition, the results also show that though prostate cancer cells are androgen independent, they remain responsive to prolactin. This could have important implications for the treatment and management of prostate cancer.

Differential associations between the cytoplasmic regions of the interleukin-12 receptor subunits beta1 and beta2 and JAK kinases

The role of the cytoplasmic regions of interleukin-12 receptors (IL-12R) beta1 and beta2 in stimulating proliferation was examined. The transmembrane and cytoplasmic regions of IL-12Rbeta1 or IL-12Rbeta2 were fused to the extracellular domain of the epidermal growth factor (EGF) receptor, yielding chimeric receptors E12R1 and E12R2, respectively. These chimeras were stably transfected into BaF3 cells, a factor-dependent murine pro-B cell line. Only E12R2 or E12R1+E12R2 transfectants were capable of EGF-dependent proliferation. EGF-dependent phosphorylation of E12R2, JAK2, Tyk2, and STAT3 was observed. JAK2 was phosphorylated in E12R1-, E12R2-, and E12R1+E12R2-expressing cells. However, direct associations were detectable only between E12R2 and JAK2. Tyk2 phosphorylation was observed only in cells expressing E12R1 or E12R1+E12R2. In parallel with this activation pattern, direct interactions only between Tyk2 and E12R1 were demonstrable. Phosphorylation of STAT3 was observed in cells expressing E12R1, E12R2, and E12R1+E12R2. The expression levels of STAT4 protein in BaF3 cells are undetectable by the methods employed here; therefore, STAT4 phosphorylation was not observed. Taken together, the data indicate that differential interactions take place between the cytoplasmic regions of the two IL-12R subunits and JAK2/Tyk2 and that the cytoplasmic region of IL-12Rbeta2 alone is capable of delivering a proliferative signal.

Synthesis, antitumor activity and acute toxicity of diammine/diamino-cyclohexane platinum(II) complexes with oxygen-ligating leaving group

In order to clarify the relation between the reactivity of the leaving groups in cisplatin-like complexes and their activity / toxicity, six new complexes of the formula Pt(NH3)2X and Pt(dach)X (where X is selenato, anion of squaric acid, or demethylcantharic acid) have been synthesized and compared. These complexes have been characterized by elemental analysis, infrared spectroscopy, and conductivity measurements. Six human neoplastic cell lines (HCT, KB, BGC, HL-60, K-563 and Bel-7402) were used to screen these compounds. The results demonstrated that four of them have comparable IC50 and even lower IC50 in a few kinds of tumor cell lines compared to cisplatin. Their LD50 values showed that the toxicity of these platinum complexes is related to the reactivity of the leaving groups. All of these complexes have lower acute toxicity than cisplatin, but the anticancer activity is not affected.

The chirality selectivity in the uptake of platinum (II) complexes with 1,2-cyclohexanediamine isomers as carrier ligand by human erythrocytes

The uptake kinetics of cisplatin analogs of 1,2-cyclohexanediamine(dach) isomers with various leaving groups, by human erythrocytes in plasma isotonic buffer, were studied. The experimental results showed that the uptake rate constants (k values) decrease with the change of leaving group in the sequence: chloride (Cl) > squaric acid (SA) > oxalate (OX) > demethylcantharic acid (DA), with the same dach isomer as carrier group. It is noteworthy that for the platinum (II) complexes with the same leaving group, the k values always reduce as: 1R, 2R-dach > 1R, 2S-dach > 1S, 2S-dach. This result reflects the chirality selectivity. No differences in reactivity to protein thiols and effects on membrane permeability were found for the R,R-, R,S-, S,S-isomeric complexes. It is proposed that the chirality selectivity in uptake is due to the recognition of the chirality of the platinum complexes by the erythrocyte membrane. The interactions between the chiral platinum complexes and the head groups of the membrane phospholipid molecules are probably involved.

Approaches and reconstruction in skull base operation

OBJECTIVE

To design convenient lateronasal and infrafrontal approaches or lateronasal subvolution approach to radically resect skull base tumors involving cranial cavity.

METHODS

From 1987 through 1994, 22 patients with malignant tumors, 6 with benign tumors, one with a giant sphenoid sinus cyst and one with intranasal meningoencephalocele underwent the operation. Twenty-three cases had anterocranial fossa involved; 4, midcranial fossa; 2, anteromedial cranial fossa; and 1 case, posteromedial cranial fossa. Among the patients with malignant tumors, 11 underwent expansive maxillectomy and 10 had orbital contents resected. The intracranial approaches through lateronasal and infrafront (21 cases), nasal columella lateral subvolution (3 cases) and other approaches were used.

RESULTS

The reconstruction of bony skull base defect in excess of 3.00 cm x 3.00 cm with total front musculocutaneous flap (8 cases), galeal and pericranial flap (5 cases) or other tissues (3 cases) has effectively prevented meningoencephalocele. Twelve cases had the dura resected in a range of 2.00 cm x 2.00 cm to 7.00 cm x 6.00 cm. Reconstruction of the dura defect with autofascia lata in 9 cases and other tissues in 3 cases effectively prevented the cerebrospinal fluid leak. Eight of 22 (36.4%) patients with malignant tumors have been alive and free of disease for 3-7 years after the operation. Six patients with benign tumors, one patient with giant sphenoid sinus cyst and one with meningoencephalocele were cured with this reconstructing method.

CONCLUSIONS

Frontal musculocutaneous and pericranial flaps have advantages over free bone because of easy surviving and easy operating without occurrence of osteonecrosis and exclusive reaction.

An observation on otoacoustic emission and ultrastructure of cochlea in experimental autoimmune inner ear disease

OBJECTIVE

To acquire the detailed knowledge of immune lesion of inner ear.

METHODS

A simultaneous study on physiology and ultrastructure was carried out in guinea pigs immunized with homogenous inner ear antigen. The specific antibody was analysed by a modified immunotransfer electrophoresis method.

RESULTS

Three positive bands (with molecular weights of 68.0 kD, 62.7 kD and 60.1 kD) were found in all the sera of immunized animals but not in the control animals. Threshold shift of auditory brainstem response over 10dB HL was found in 42% of secondary system immunized animals and 32% of secondary endolymphatic sac (e.sac) immunized animals. Amplitude of distortion production otoacoustic emission dropped obviously in the above two groups. Transmission electron microscope showed the mitochondria of outer hair cells in the cochlea was impaired in animals with auditory disorder.

CONCLUSIONS

The research suggests that the immune reaction against homogenous inner ear antigen results in dysfunction of hydroxycorticosteroid during the early stage.

Establishment of an in-use testing method for evaluating disinfection of surgical instruments using the duck hepatitis B model

Nosocomial transmission of hepatitis B virus (HBV), associated with interventional procedures, has been attributed to its survival on improperly decontaminated instruments. To date, guidelines for chemical disinfection of potentially contaminated heat-sensitive instruments have been based largely on extrapolation of data from in-vitro disinfectant testing. Direct infectivity testing has not been possible for HBV because of the lack of a practical culture assay or susceptible experimental animal model. In this study the related duck hepadnavirus was used to simulate in-vivo transmission of a HBV during surgery, and to evaluate the effectiveness of 2% glutaraldehyde disinfection of surgical laparoscopes. Multiple laparoscopic liver biopsies were performed on 'biohazardous' duck hepatitis B (DHBV) positive ducks. Laparoscopes were then subjected to different disinfection regimes using 2% glutaraldehyde, and residual infectivity tested by placing their tips into the peritoneal cavities of uninfected four-day-old ducklings. Direct transmission of DHBV occurred in all ducks when laparoscopes were not washed. Rinsing with water lowered the transmission rate to 64% and no infection transmission occurred after 5 min of contact time with the disinfectant. In contrast, previous in-vitro studies had shown complete viral inactivation after a shorter period of disinfection. It is postulated that the longer inactivation time observed in our study may be a result of surface interactions of virus and instrument, interfering with disinfectant access or activity. Tests of instrument surface samples for viral DNA by the polymerase chain reaction (PCR) did not correlate with transmission of virus infection in vivo. PCR is an inappropriate test for evaluating the efficacy of disinfectant action despite its sensitivity. This in use method will allow testing of other decontamination procedures and their effectiveness on more complex surgical instruments.

Cloning of a cDNA encoding the 21.2 kDa oleosin isoform from Arabidopsis thaliana and a study of its expression in a mutant defective in diacylglycerol acyltransferase activity

A full-length cDNA clone (pA23) of 832 bp encoding an oleosin from Arabidopsis thaliana was isolated by differential screening of a silique-specific cDNA library with probes prepared from poly(A)+ RNA isolated from developing seeds of wild-type (WT) Arabidopsis and from mutant AS11 with a lesion affecting diacylglycerol acyltransferase (DGAT) activity during embryo development. The encoded protein has a calculated molecular mass of 21.2 kDa, and its amino acid sequence shows strong sequence homology and structural similarity to other known oleosins. Transcription of the oleosin gene during seed development was both reduced and delayed in AS11 compared to WT. However, the level of oleosin protein did not appear to be down-regulated during seed development, and at maturity, the overall level of oleosin protein was similar in both WT and AS11. These findings indicate that regulation of oleosin gene expression is part of a highly complex, and co-ordinated expression of storage lipid biosynthesis and related (oleosin) genes during oilseed development.

Evidence for a role of Hsp70 in the regulation of the heat shock response in mammalian cells

Heat and other environmental insults (stress) cause unfolding of proteins, triggering the activation of heat shock transcription factor HSF (HSF1 in vertebrates) that, in higher eukaryotes, involves trimerization of the factor and acquisition of heat shock element (HSE) DNA-binding ability. Interaction of activated HSF1 with HSEs in promoters of genes encoding heat shock proteins (Hsps) enhances their expression. It was suggested that Hsp70 may function as the negative regulator of HSF1. In the simplest model, stress-unfolded proteins would compete with monomeric HSF1 for Hsp70 binding. This competition would result in dissociation of an HSF1-Hsp70 complex, allowing trimerization of released HSF1 monomers. In support of this model, we present evidence herein that 1) non-activated HSF1 forms a 1:1 complex with Hsp70, 2) both rates of heat-induced appearance of HSF1 oligomers and rates of disappearance of HSF1 heterodimers and monomers decrease when concentrations of unengaged Hsps are increased, and 3) transient overexpression of Hsp70 inhibits heat activation of HSF1.

Regulation of citrate metabolism by androgen in the LNCaP human prostate carcinoma cell line

Citrate production and accumulation are characteristic physiological functions of the prostate gland that are regulated by testosterone and prolactin. Results reported here show that treatment of LNCaP cells with dihydrotestosterone (DHT) resulted in increased intracellular citrate and increased citrate accumulation in the medium. Moreover, DHT also caused an increase in both mitochondrial aspartate aminotransferase (mAAT) activity and the steady state level of pmAAT (precursor) mRNA. Androgen treatment increased the rate of citrate oxidation by LNCaP cells as it does in rat ventral prostate which suggests that DHT increased aconitase activity in LNCaP cells. The results reported here are consistent with the operation of the glutamate-aspartate-citrate pathway that we described for rat ventral prostate. In addition, these results provide the first evidence that androgen responsive functions associated with citrate metabolism are retained in LNCaP cells. In addition, and more important, these results suggest that the more aggressive PC-3 carcinoma cell line has a higher rate of citrate oxidation than the less aggressive LNCaP cell line. This could have significant implications for our understanding of the relationship between alterations in prostate citrate metabolism and expression of the malignant phenotype.

Induction of Lipid and Oleosin Biosynthesis by (+)-Abscisic Acid and Its Metabolites in Microspore-Derived Embryos of Brassica napus L.cv Reston (Biological Responses in the Presence of 8[prime]-Hydroxyabscisic Acid)

Microspore-derived (MD) embryos of Brassica napus L. cv Reston were used to test the effects of (+)-abscisic acid ([(+)-ABA]) and its metabolites, 8[prime]-hydroxyabscisic acid (8[prime]-OH ABA) and (-)-phaseic acid (PA), on the accumulation of very long-chain monounsaturated fatty acids (VLCMFAs) and induction of genes encoding a 19-kD oleosin protein and a [delta]15 desaturase during embryogenesis. Developing early to mid-cotyledonary MD embryos at 16 to 19 d in culture were treated with 10 [mu]M hormone/metabolite for 4 d. At various times during incubation, embryos and medium were analyzed to determine levels of hormone/metabolite, VLCMFAs, and oleosin or [delta]15 desaturase transcripts. The VLCMFAs, 20:1 and 22:1, primarily in triacylglycerols, increased by 200% after 72 h in the presence of (+)-ABA and 8[prime]-OH ABA relative to the control. In contrast, treatment with PA for 72 h had little effect (20% increase) on the level of VLCMFAs. The first 24 to 72 h of (+)-ABA treatment were critical in the induction of VLCMFA biosynthesis, with 8[prime]-OH ABA lagging slightly behind (+)-ABA in promoting this response. The accumulation of VLCMFAs was positively correlated with an increase in elongase activity. (+)-ABA and its 8[prime]-OH ABA metabolite induced the accumulation of a 19-kD oleosin transcript within 2 to 4 h in culture. In addition, both (+)-ABA and 8[prime]-OH ABA induced the same level of [delta]15 desaturase transcript by 8 h. PA had no effect on the induction of either oleosin or [delta]15 desaturase transcripts. To our knowledge, this is the first report of the biological activity of 8[prime]-OH ABA and of stimulatory effects of (+)-ABA and 8[prime]-OH ABA on lipid and oleosin biosynthesis.

Alteration of seed fatty acid composition by an ethyl methanesulfonate-induced mutation in Arabidopsis thaliana affecting diacylglycerol acyltransferase activity

In characterizing the enzymes involved in the formation of very long-chain fatty acids (VLCFAs) in the Brassicaceae, we have generated a series of mutants of Arabidopsis thaliana that have reduced VLCFA content. Here we report the characterization of a seed lipid mutant, AS11, which, in comparison to wild type (WT), has reduced levels of 20:1 and 18:1 and accumulates 18:3 as the major fatty acid in triacylglycerols. Proportions of 18:2 remain similar to WT. Genetic analyses indicate that the fatty acid phenotype is caused by a semidominant mutation in a single nuclear gene, designated TAG1, located on chromosome 2. Biochemical analyses have shown that the AS11 phenotype is not due to a deficiency in the capacity to elongate 18:1 or to an increase in the relative delta 15 or delta 12 desaturase activities. Indeed, the ratio of desaturase/elongase activities measured in vitro is virtually identical in developing WT and AS11 seed homogenates. Rather, the fatty acid phenotype of AS11 is the result of reduced diacylglycerol acyltransferase activity throughout development, such that triacylglycerol biosynthesis is reduced. This leads to a reduction in 20:1 biosynthesis during seed development, leaving more 18:1 available for desaturation. Thus, we have demonstrated that changes to triacylglycerol biosynthesis can result in dramatic changes in fatty acid composition and, in particular, in the accumulation of VLCFAs in seed storage lipids.

[Clinical evaluation of the vulva reconstruction with myocutaneous flap transposition after radical vulvectomy]

Thirty-three cases with carcinoma of vulva were treated in the division of gynecologic oncology from July, 1989 to April, 1994. Out of 33 cases, 18 with stage II or III underwent radical vulvectomy, pelvic and inguinal lymphadenectomy. These were divided into 3 groups based on the different methods of vulval reconstruction: (1) simple suture group (6 cases); (2) cutaneous flap group (4 cases); (3) myocutaneous flap transposition group (8 cases). The large defect area left by radical vulvectomy and inguinal lymphadenectomy was reconstructed by myocutaneous flap, tensor fascia latae flap, in 6 cases and musculus gracilis myocutaneous flap in 2 cases. All the cases in group 1, 2 suffered from breakdown of wounds, infection or necrosis, resulting in long term hospitalization (mean duration 36.3 days), delayed scar pains, and problems in walking or sexual activity. Primary wound-healing was observed in the 6 cases of group 3, wound infection occurred in one case with diabetes and one case of relapse cancer after radiation therapy. The mean duration of hospitalization in group 3 was 20 days, and neither scar pains nor problems in sexual activity was found after a follow up of 6 months to 4 years. One case in this group died of brain metastases of cancer of vulva. The indications and advantages of myocutaneous flap transposition are discussed. It is suggested that myocutaneous flap transposition surgery is clinically one of the best and safest methods for reconstruction of the vulva and it can improve the quality of life.

Asparagine-linked glycosylation in Schizosaccharomyces pombe: functional conservation of the first step in oligosaccharide-lipid assembly

The gene gpt encoding uridine diphosphate N-acetyl-D-glucosamine:dolichol phosphate N-acetylglucosaminylphosphoryltransferase (L-G1PT) was isolated by screening a Schizosaccharomyces pombe genomic DNA library in lambda phage under low-stringency hybridization using the Saccharomyces cerevisiae gene ALG7 as probe. Sequencing 2.4 kb of S. pombe DNA revealed a 1338-bp open reading frame (ORF) encoding a hydrophobic protein of 446 amino acids with a predicted molecular weight of 49,852. The S. pombe protein was 50% identical to the S. cerevisiae protein and 43% identical to the protein from Chinese hamster ovary (CHO) cells. Overexpression of the gpt gene in S. pombe cells increased resistance to tunicamycin 25-fold and increased the specific activity of the enzyme in isolated cell membranes 13-fold. This was accompanied by a 50-fold increase in poly(A)+ RNA hybridizing to the gpt probe. Northern analysis indicated a single 1.8-kb message is transcribed from the gpt gene. The gpt gene is essential for viability of S. pombe. Cells containing a disrupted ORF could be rescued by an expression plasmid containing either the intact S. pombe gpt ORF or the CHO L-G1PT cDNA. The S. pombe gpt gene was mapped to chromosome 2 near top1 and ade1.

Genomic organization and expression of hamster UDP-N-acetylglucosamine:dolichyl phosphate N-acetylglucosaminyl phosphoryl transferase

The hamster gene for uridine diphosphate N-acetyl-D-glucosamine:dolichyl phosphate N-acetylglucosaminyl phosphoryl transferase (L-G1PT) was found to extend over 6.5 kb and to contain nine exons. The exons ranged in size from 63 to 214 bp, encoding the 408 amino acid protein. The introns ranged from 85 bp to 1.4 kb. Upstream 5' sequences included two possible TATA boxes, one possible CCAAT box and at least two potential GC boxes. Heterologous expression was successful in Schizosaccharomyces pombe, and resulted in cells that were tunicamycin resistant and had 12-fold more L-G1PT activity than wild-type cells. Antiserum prepared to a hydrophilic peptide (residues 300-320) of the L-G1PT protein reacted with a 35-36 kDa protein in membrane samples from Chinese hamster ovary (CHO) cells and S. pombe cells that had increased levels of L-G1PT activity. In both cases, antigenic peptide competed with the 35-36 kDa protein detected by the antiserum.

[Laboratory diagnosis of autoimmune sensorineural hearing loss with modified western blotting method]

Anti-membranous labyrinth proteins antibody were tested in suspectable autoimmune sensorineural hearing loss (ASNHL) with a modified western blotting method. 5 strongly positive bands (including 68,000) existed in at most 18 of 25 cases (72%). This method was found to be more sensitive than the routine one (40%). Anti-membranous proteins of Klebsiella pneumoniae antibodies were also found in 7 of 9 tested patients.

[Pharmacokinetics and bioavailability study on acetaminophen oral drop in healthy volunteers]

The concentrations of acetaminophen in human plasma were determined by RP-HPLC after administration of a single oral dose of 1000 mg acetaminophen oral drop or tablet to eight normal male volunteers in a crossover study. The concentration vs time curves of acetaminophen all fitted the two compartment model. The Cmax in oral drop and tablet were 11.23 +/- 0.93 and 8.79 +/- 0.93mg/L, respectively; Tmax were 0.86 +/- 0.08 and 1.48 +/- 0.39h; T1/2 beta 3.03 +/- 0.79 and 2.51 +/- 1.10 h; AUC 42.35 +/- 6.20 and 40.60 +/- 6.79mg/L.h. When AUC in tablet was 100%, the relative bioavailability of acetaminophen oral drop was 105.58%. The results showed that the oral drop and tablet are bioequivalent.