The mammalian ARF-like protein 1 (Arl1) is associated with the Golgi complex

A rat cDNA clone was isolated which encodes a protein displaying characteristics of a ras-like small GTPase. The deduced amino acid sequence shows the highest amino acid identity (79%) with the Drosophila ARF-like protein 1 (dArl1) among all the known members of the ras-like small GTPase superfamily. The encoded protein was tentatively named rat Arl1 (rArl1). Northern blotting analysis revealed that the rArl1 gene is ubiquitously expressed in rat tissues. Recombinant rArl1 fused to glutathione-S-transferase (GST) to create GST-rArl1 binds GTP-gamma-S in a dose-dependent manner. Polyclonal antibodies raised against two unique rArl1 peptides recognized a 22 kDa protein in total NRK cell lysate. Immunofluorescence microscopy of NRK cells revealed discrete perinuclear labelling that could be competed out by GST-rArl1 but not GST. Examination of 8 additional cell lines revealed a similar labelling, suggesting that the antigen recognised by the antibodies is conserved and widely-expressed. Co-localization experiments in NRK cells with antibodies to mannosidase II and a newly identified cis-Golgi protein, p28, showed that rArl1 is localized to the Golgi complex. When cells were treated with nocodazole, the Golgi complex marked by mannosidase II and p28 was fragmented into punctate structures scattered throughout the cell, in which rArl1 was colocalized. Treatment with brefeldin A (BFA) resulted in the redistribution of rArl1 and mannosidase II into the cytoplasm and endoplasmic reticulum, respectively. The kinetics of the redistribution of rArl1 in response to BFA differ from those of ARF and beta-COP, two components of non-clathrin coated vesicles.

Segregation of ERGIC53 and the mammalian KDEL receptor upon exit from the 15 degrees C compartment

Protein trafficking along the exocytotic pathway occurs by vesicular transport between successive membranous compartments. Transport from the endoplasmic reticulum (ER) to the Golgi apparatus has been proposed to be bridged by a morphologically defined ER-Golgi intermediate compartment (ERGIC). Using the subcellular dynamics of two markers for the ERGIC, the 53 kDa protein ERGIC53 and the mammalian KDEL receptor (KDEL-R), we have investigated the biochemical and physiological characteristics of ER-Golgi anterograde and retrograde transport. The KDEL-R at steady state is mainly confined to the perinuclear Golgi region while the ERGIC53 has a more elaborate distribution, including the ER. Both proteins can be colocalized to spotty structures distributed throughout the cytoplasm by incubating the cells at 15 degrees C. Upon returning the cells to 37 degrees C, the direction of transport for the two proteins diverged. KDEL-R was seen to emanate into tubular structures which eventually culminated in a focused, perinuclear staining. These dynamic changes are consistent with the anterograde transport process from the ER to the Golgi apparatus. ERGIC53, on the other hand, was distributed into an extended reticular network as well as the nuclear envelope, a staining pattern characteristic of the ER. With time, ERGIC53 was seen to return to the spotty structures again. The ER retrieval of ERGIC53 is consistent with the fact that the protein contains a dilysine motif which may function as an ER retrieval signal. The movement of ERGIC53 into the ER is not affected by microtubule disrupting agents, which inhibit the movement of KDEL-R to the Golgi. Both the processes are, however, sensitive to the alkylating agent N-ethylmaleimide. When reconstituted in vitro using digitonin permeabilized cells, the movement of ERGIC53 into the ER has a requirement for metabolic energy, is partially inhibited by the nonhydrolyzable guanine nucleotide analog GTP gamma S but could not be made to be cytosol dependent. These results documented the convergence of anterograde transport and retrograde transport at the 15 degrees C compartment and implied the existence of a segregation or a sorting process that would result in the segregation of proteins with different targeting signals in the structure.

[Dysgerminoma of the ovary: a clinical retrospective analysis of 60 cases]

OBJECTIVE

To study the treatment methods and the prognostic factors of pure dysgerminoma of the ovary.

METHODS

Sixty cases histologically confirmed pure ovarian dysgerminoma treated in our hospital, from May 1959 to Oct. 1992 were retrospectively analysed. Factors mainly studied were: age, symptoms, clinical staging and treatment methods.

RESULTS

The median age of this series was 21. The main symptoms were abdominal mass, pain and distension. Thirty two out of 60 cases were stage I, 2 were stage II, 5 were stage III and 21 with recurrences or persistence of the disease. All cases excepting one case received surgery alone were treated by surgery combined with external radiotherapy or chemotherapy. Nine cases died of the disease. The actual 5-year survival rate was 85.17%. The survival rate for patients with postoperative adjuvant chemotherapy is 95% and that for patients with radiotherapy is 76.1%; no statistic significance was shown.

CONCLUSIONS

In pure ovarian dysgerminoma surgery combined with radiotherapy or chemotherapy showed high complete remission rates and excellent survival rates. For younger patients and those with gestation desires as well as patients with advanced diseases, adjuvant chemotherapy following surgery might be a better choice.

[Analysis of heavy chain immunoglobulins gene and T-cell receptor delta gene in children with acute leukemia]

IgH gene, TCR delta gene rearrangements and Tal-1 gene deletion were analysed by using PCR, Southern blot and DNA sequencing methods in newly diagnosed BM samples from children with AL. The DNAs from leukemic cells in 102 children were detected with PCR. The results showed that IgH gene rearrangement mainly occurred in B Precursor ALL (37/49). Six PCR products were further analysed by DNA sequencing. Less homogene and bias of JH gene usage were found in analysed DNA sequences. V delta 2-D delta 3 rearrangement of 78 samples from ALL was analysed with PCR method. V delta 2-D delta 3 rearrangements mainly observed in B precursor ALL and related HAL. V delta 2-D delta 2-N-D delta 3 rearrangement was found in a sequence of PCR product. Three cases of Tal-1 gene deletion were observed in all studied 70 samples of AL. They all were in stage I of thymus differentiation. We conclud that PCR detection of those genes are useful in the diagnosis of clonality of AL, DNA sequencing of PCR products is the base of preparing clonal specific probes, and dynamic analysis of IgH gene rearrangement using PCR may be helpful in detection of residual clones.

Monoclonal antibody HFD9 identifies a novel 28 kDa integral membrane protein on the cis-Golgi

We have raised a monoclonal antibody (mAb) (HFD9) that detects a 28 kDa protein (p28) enriched in the Golgi membrane. p28 was localized to the perinuclear Golgi region in all cell lines thus far examined. Its Golgi localization was confirmed by its colocalization with Golgi markers using indirect immunofluorescence microscopy. Immunogold labelling demonstrates that the majority of p28 was localized on the cis-Golgi and its associated structures. Two independent experiments demonstrate that the p28 epitope recognized by mAb HFD9 is exposed to the cytosol. Extraction of Golgi membranes with a variety of reagents revealed that p28 behaves like an integral membrane protein. mAb HFD9 thus defines a novel 28 kDa integral membrane protein on the cis-Golgi. To our knowledge, p28 represents the first integral membrane protein of the Golgi system identified via the antibody approach whose epitope is cytoplasmically-oriented and highly-conserved. Monoclonal antibody HFD9 will thus provide a useful tool for further studies on the cis side of the Golgi, which is not well characterised due to the lack of good markers.

Retardation of a surface protein chimera at the cis Golgi

Dipeptidyl peptidase IV (D4) and the alpha subunit of human chorionic gonadotrophin (alpha hcg) are plasma membrane and secretory proteins, respectively. In the course of studies to understand mechanisms involved in transport along the exocytotic pathway, the ectoplasmic domain of D4 was replaced by the mature polypeptide of alpha hcg, resulting in the membrane anchored chimera, D4 alpha hcg. Surprisingly, when transfected into Chinese hamster ovary (CHO) and Madin-Darby canine kidney (MDCK) cells, strong perinuclear Golgi staining was predominant, in addition to the expected surface staining. By following the biogenesis and transport of the molecule, it was established that newly synthesized D4 alpha hdg is eventually transported to the cell surface but only after a significant retardation in the Golgi apparatus. The compartment of retardation was identified as the early or cis Golgi, before the medial Golgi, where resistance to endoglycosidase (endo) H is conferred. As a result of the transport retardation of the chimera, we were able to document the appearance of an endo D sensitive intermediate, which is usually too transient to be apparent in normal cells. The retardation of this chimera in the cis Golgi complements our previous report in which the D4 molecule with its transmembrane domain replaced by that of aminopeptidase N resulted in retardation in the trans Golgi/trans Golgi network in MDCK and CHO cells [Low, S. H., Tang, B. L., Wong, S. H., & Hong, W. (1994) J. Biol. Chem. 269, 1985-1994).(ABSTRACT TRUNCATED AT 250 WORDS)

A role for retinoblastoma protein in potentiating transcriptional activation by the glucocorticoid receptor

The Saccharomyces cerevisiae SNF2/SWI2 protein is essential for the regulated expression of a variety of genes. A human SWI2/SNF2 homologue, hBrm, is a positive participant in glucocorticoid-receptor-mediated transcription, but its mechanism of action is not known. The retinoblastoma protein, RB, has also been shown to stimulate the transcription of several genes, although the target for RB has not been identified in any of these transcriptional events. Here we show that RB upregulates glucocorticoid-receptor-mediated transcription. The effect of either RB or hBrm is dependent on the presence of the other. Furthermore, we demonstrate that RB and hBrm interact with one another in vitro and in vivo. These results highlight a new role for RB, which is to interact with hBrm in order to potentiate glucocorticoid-receptor-activated transcription.

Cell type differences in Golgi retention signals for transmembrane proteins

The transmembrane domain of Golgi resident proteins such as beta-galactoside alpha 2,6-sialyltransferase (ST) and N-acetylglucosaminyltransferase 1 (NT) contain a Golgi retention signal which confers Golgi retention to reporter proteins appended to them in the appropriate context. Thus, chimeras of the cell surface protein dipeptidyl peptidase IV containing the transmembrane domain of ST and NT are retained in the Golgi apparatus in MDCK and COS cells, as assessed by indirect immunofluorescence microscopy. Transfection of these chimeric constructs into CHO cells, however, results in their transport to vesicular structures which do not colocalize with that of an endogenous Golgi marker, mannosidase II. Furthermore, the staining pattern of these structures are not affected by brefeldin A. Biochemical analysis of the transgene products in pulse-chase experiments revealed that the chimeric proteins eventually become resistant to endoglycosidase H, suggesting that they are transported beyond the medial Golgi and therefore the vesicular structures are likely to be post-Golgi. The vesicular structures colocalized well with a lysosomal marker, cathepsin D, and also with internalized FITC-dextran chased into the lysosomal compartment. Monitoring the cell surface appearance of the chimeric protein suggests that the majority is transported directly to the lysosomal compartment. Golgi retention can be completely restored for ST and improved for NT by the inclusion of sequences flanking the transmembrane domain. Our results reflect cell type differences in the interpretation of the transmembrane domain Golgi retention signal, established that general Golgi retention of type II glycosyltransferases requires the hydrophilic flanking sequence as well as the transmembrane domain, and demonstrate that proteins which escape Golgi retention may be channeled to the lysosomal pathway.

Additive interactions between propofol and ketamine when used for anesthesia induction in female patients

BACKGROUND

Propofol and ketamine may be paired for anesthesia induction and for total intravenous anesthesia. The nature of any sedative interactions occurring between propofol and ketamine are unknown. The combination when used for anesthesia induction in female patients was studied.

METHODS

Quantal dose-response curves were determined in 180 female patients to whom the drugs were administered individually and in combination. Two minutes after administering the drugs, two endpoints were assessed. First, loss of response to verbal command (hypnosis) and then, in those who failed to respond to this endpoint, loss of response to a 5-s transcutaneous tetanus (anesthesia). Interactions were analyzed by fitting the data to a mathematical model in which response was analyzed in terms of the doses of the two drugs and an additional term included to describe nonadditive interactions. The incidences of apnea, arterial pressure, and heart rate changes during the first 5 min were recorded.

RESULTS

At the hypnotic endpoint, the ED50s were 1.10 mg/kg propofol (95% CIs 0.93-1.27), 0.39 mg/kg ketamine (95% CIs 0.27-0.46), and the combination of 0.63 mg/kg propofol and 0.21 mg/kg ketamine (95% CIs 0.53/0.18-0.73/0.24). At the anesthetic endpoint, the ED50s were 1.85 mg/kg propofol (95% CIs 1.58-2.36) 0.66 mg/kg ketamine (95% CIs 0.58-0.77), and the combination of 1.05 mg/kg propofol and 0.35 mg/kg ketamine (95% CIs 0.88/0.29-1.27/0.42). The effects were additive at both endpoints; there was no evidence of an interaction. The ED50s for apnea were 1.61 mg/kg propofol (95% CIs 1.39-1.94), greater than 0.85 mg/kg ketamine and for the combination 1.50 mg/kg propofol and 0.50 mg/kg ketamine (95% CIs 1.15/0.38-3.09/1.03). The addition of ketamine did not significantly alter the ED50 for apnea of propofol. There was a significant difference in the arterial pressures among the three groups (P < 0.001). Using the combination, the cardiostimulant effects of ketamine balanced the cardiodepressant effects of propofol. There was no change in arterial pressure or heart rate after the noxious stimulus.

CONCLUSIONS

When using the combination, doses were additive at hypnotic and anesthetic endpoints. Ketamine had no influence on the incidence of apnea after propofol, and the net hemodynamic effects were minimal.

Localization of the Lys, Asp, Glu, Leu tetrapeptide receptor to the Golgi complex and the intermediate compartment in mammalian cells

The carboxyl-terminal Lys-Asp-Glu-Leu (KDEL), or a closely-related sequence, is important for ER localization of both lumenal as well as type II membrane proteins. This sequence functions as a retrieval signal at post-ER compartment(s), but the exact compartment(s) where the retrieval occurs remains unresolved. With an affinity-purified antibody against the carboxyl-terminal sequence of the mammalian KDEL receptor, we have investigated its subcellular localization using immunogold labeling on thawed cryosections of different tissues, such as mouse spermatids and rat pancreas, as well as HeLa, Vero, NRK, and mouse L cells. We show that rab1 is an excellent marker of the intermediate compartment, and we use this marker, as well as budding profiles of the mouse hepatitis virus (MHV) in cells infected with this virus, to identify this compartment. Our results demonstrate that the KDEL receptor is concentrated in the intermediate compartment, as well as in the Golgi stack. Lower but significant labeling was detected in the rough ER. In general, only small amounts of the receptor were detected on the trans side of the Golgi stack, including the trans-Golgi network (TGN) of normal cells and tissues. However, some stress conditions, such as infection with vaccinia virus or vesicular stomatitis virus, as well as 20 degrees C or 43 degrees C treatment, resulted in a significant shift of the distribution towards the trans-TGN side of the Golgi stack. This shift could be quantified in HeLa cells stably expressing a TGN marker. No significant labeling was detected in structures distal to the TGN under all conditions tested. After GTP gamma S treatment of permeabilized cells, the receptor was detected in the beta-COP-containing buds/vesicles that accumulate after this treatment, suggesting that these vesicles may transport the receptor between compartments. We propose that retrieval of KDEL-containing proteins occurs at multiple post-ER compartments up to the TGN along the exocytotic pathway, and that within this pathway, the amounts of the receptor in different compartments varies according to physiological conditions.

Cytosolic factors block antibody binding to the C-terminal cytoplasmic tail of the KDEL receptor

The mammalian KDEL receptor is an extremely hydrophobic membrane protein. One of the longest stretches of hydrophilic sequence resides at the C-terminus. Various antibodies against a synthetic peptide corresponding to this region confirmed that the C-terminus is exposed to the cytoplasm. It was observed that antibody binding to the C-terminus of the KDEL receptor was diminished during immunofluorescence microscopy procedures which involved fixation prior to permeabilization as compared to when cells were permeabilized before fixation. Binding of both polyclonal and monoclonal antibodies, as assessed by indirect immunofluorescence microscopy in digitonin permeabilized cells, was inhibited by preincubation with rat liver cytosol. This inhibition was not observed with antibody against another membrane protein (p28) with a cytoplasmically exposed epitope also residing in the Golgi/intermediate compartment. Rabbit reticulocyte lysate had a similar effect while Schizosaccharomyces pombe cytosol inhibited binding to a greater degree than Saccharomyces cerevisiae cytosol. This inhibition by cytosol was prevented by coincubation with the antibody and was dose-dependent on the cytosol. Inhibition did not occur on ice or at 15 degrees C, or when the cytosol was energy-depleted by apyrase treatment. Interestingly, pretreatment of permeabilized cells with N-ethylmaleimide or its addition into the incubation mixture abolished inhibition. N-ethylmaleimide-treated cytosol, however, remained inhibitory. The findings suggest the existence of cytosolic factor (s) which interacts specifically with the cytoplasmic C-terminus of the KDEL receptor, which are likely to be components of the KDEL protein retrieval machinery.

[Trial vaginal delivery for women with previous cesarean section]

A retrospective analysis was made on 85 cases of trial labor after previous cesarean section (CS) and compared with 100 primiparous vaginal deliveries (as control) during the last 10 years. Oxytocin infusion has been used in 61 trial cases to induce and/or to accelerate labor, and valium, procaine and atropine administered during the labor process in 23 of them. 65 of the 85 cases (76.5%) successfully delivered through the vagina (VD group), while 20 cases (23.5%) had repeat CS following failure in trial labor (CS group), and 3 women had reatened uterine rupture. There was 1 neonatal death in the VD trial labor group. No obvious difference in the Apgar scores of newborns was found between the CS group and the controls, and the duration of the labor process was much shorter in the VD trial group than that in the primiparae (7.51 +/- 2.44 hrs vs. 9.10 +/- 3.75 hrs) (P < 0.01). This study indicated that following a previous uneventful transverse lower segment cesarean section, trial labor should be encouraged under supervision.

Overexpression of E2F-1 in rat embryo fibroblasts leads to neoplastic transformation

The transcription factor E2F has been implicated in controlling the activation of multiple genes associated with cell proliferation. E2F-1, which is a component of E2F, can promote oncogenesis when transfected into REF cells. The transformation caused by E2F-1 correlates with constitutive overexpression of the transgene, increased transcription of E2F-dependent genes and the enhancement of two E2F DNA binding complexes containing the retinoblastoma susceptibility gene product (Rb) and E2F-1. The oncogenic potential of E2F-1 is dependent on functional DNA binding and transactivation domains but does not require the ability to interact directly with Rb. These findings provide the first direct evidence that sustained unregulated expression of E2F-1 can lead to the loss of cell proliferation control and that E2F-1 is a key component in cell cycle control.

[Influences of lipid peroxidative injury to endothelial cells on adherence and migration of monocyte]

The influences of lipid peroxidative injury to endothelial cells (EC) on adherence to EC and migration into subendothelial space of human monocytes were studied by using a modified vascular endothelial model in vitro. Lipid peroxidative injury to cultured human umbilical vein EC was initiated by treating the EC with diamide. The results showed that injury to EC could enhance adherence to EC and migration into subendothelial space of monocytes. Monocytes mainly adhered to the intercellular space and surface of injured EC. In the area of EC denudation, the number of monocytes which migrate into the subendothelial space was more than that in the area without denudation. These results suggested that enhanced adherence to EC and migration into subendothelial space of monocytes caused by lipid peroxidative injury to EC may play an important role in atherogenesis.

Golgi retardation in Madin-Darby canine kidney and Chinese hamster ovary cells of a transmembrane chimera of two surface proteins

Dipeptidyl peptidase IV (DDD) is a type II plasma membrane protein. Replacement of its transmembrane domain with that of another surface protein, aminopeptidase N, resulted in accumulation in the Golgi apparatus of Madin-Darby canine kidney cells and a delayed Golgi to surface transport in Chinese hamster ovary (CHO) cells. The compartment of retardation was identified as post medial-Golgi, most likely to be the trans-Golgi/trans Golgi network (TGN). Compared to native DDD, the rate of endoplasmic reticulum to Golgi transport for the chimera was largely unchanged in both cell types. On the other hand, Golgi to surface transport was delayed by more than 2 h in CHO cells and essentially undetectable up to 22 h of chase in Madin-Darby canine kidney cells. The decrease in the rate of Golgi to surface transport in CHO cells resulted in a significant accumulation of the fusion protein in the trans-Golgi/TGN. This phenomena is very unlikely to be due to any drastic conformational changes, as neither the enzyme activity nor the dimerization of the constructed molecule was affected. The findings of this study indicate that the transmembrane domain, in the context of its flanking sequences, is important for efficient Golgi to cell surface transport.

Childhood-onset schizophrenia: an NIMH study in progress

An ongoing study of the phenomenology, genetics, neuropsychology, physiology (eye tracking, autonomic responsivity), neuroimaging, biochemistry, and pharmacology of childhood-onset schizophrenia is described, and pilot data are presented for the first 22 subjects. Differentiation from autism "spectrum" disorders and other poorly defined, severe neurodevelopmental disorders is needed. Eye tracking and autonomic results are similar to patterns seen in later-onset schizophrenia and possibly more striking. Magnetic resonance imaging showed larger left frontal ventricular horn area for the schizophrenia subjects, larger left caudate, and lack of normal caudate asymmetry. Fluorodeoxyglucose positron emission tomography during an auditory continuous performance task revealed decreased right parietal/occipital glucose metabolic rate in the schizophrenia subjects, which may be secondary to poor attentional performance, and increased glucose metabolic rate in three left frontal regions, a left parietal region, and the right putamen. Clozapine has been effective and well tolerated in an open trial with 12 adolescents who responded poorly to typical neuroleptics; 16 subjects have been enrolled in a double-blind comparison of haloperidol and clozapine. Longitudinal study of this narrowly defined and possibly more homogeneous group of very early-onset schizophrenia subjects will be relevant to current neurodevelopmental theories addressing the role of puberty, progression of pathology, and continuity or discontinuity with later-onset schizophrenia.

Effects of NH4Cl and nocodazole on polarized fibronectin secretion vary amongst different epithelial cell types

The extracellular matrix protein fibronectin was found to be secreted by three polarized epithelial cell lines Madin-Darby canine kidney (MDCK), Caco-2 and LLC-PK1. About 54 and 46% of fibronectin was secreted from the apical and basolateral cell surfaces, respectively, in MDCK cells. In Caco-2 and LLC-PK1 cells, the majority (about 92-93%) of fibronectin secretion occurs from the basolateral cell surface, with the remaining 7-8% from the apical surface. In all three cell types, NH4Cl was found to inhibit basolateral secretion (resulting in enhanced apical secretion), while total fibronectin secretion was not significantly affected (although a delay in secretion was observed). Nocodazole reduced total fibronectin secretion to about 70% of control levels in MDCK and Caco-2 cells, with significant inhibition on secretion from both surfaces. In contrast, total fibronectin secretion was enhanced by nocodazole in LLC-PK1 cells. Furthermore, the majority of fibronectin secretion was redirected to the apical cell surface in LLC-PK1 cells. These observations demonstrate that the nature as well as the extent of the effects of NH4-Cl and nocodazole on polarized fibronectin secretion varies amongst different epithelial cell types.

Hypnotic and anesthetic interactions between ketamine and midazolam in female patients

BACKGROUND

Midazolam, if used with ketamine for induction and maintenance of anesthesia, may attenuate hyperdynamic circulatory effects and prevent undesirable emergenic reactions. The nature of the interaction between midazolam and ketamine used for anesthesia induction was studied in female patients.

METHODS

Quantal dose-response curves were determined in 170 female patients for the drugs, individually and in combination. Two endpoints were assessed, loss of response to verbal command (hypnosis) and loss of response to a 5-s transcutaneous tetanus (anesthesia). At the hypnotic endpoint, interactions were analyzed by fitting the data to a mathematical model in which the response was analyzed in terms of the doses of the two drugs, and an additional term was included to describe nonadditive interactions. At the anesthetic endpoint, the decrease in ED50 of ketamine in the presence of midazolam was assessed because dose-related effects could not be demonstrated for midazolam alone.

RESULTS

At the hypnotic endpoint, the ED50s were: 0.15 mg/kg midazolam (95% CIs 0.11-0.38 mg/kg), 0.37 mg/kg ketamine (95% CIs 0.08-0.44 mg/kg), and the combination of 0.086 mg/kg midazolam and 0.27 mg/kg ketamine (95% CIs 0.07/0.22-0.10/0.31 mg/kg), respectively. The hypnotic effects were found to be additive, and there was no evidence of an interaction. At the anesthetic endpoint, the ED50 of ketamine alone was 0.57 mg/kg (95% CIs 0.47-0.69) and the ED50 for ketamine in the presence of midazolam was also 0.57 mg/kg (95% CIs 0.48-0.79); 0.18 mg/kg midazolam was given at this point. Midazolam had no influence on the anesthetic dose of ketamine.

CONCLUSIONS

When using the combination, doses employed should be adjusted according to the depth of central nervous system depression that is required.

[Effect of lipid peroxidation injury to endothelial cells (EC) on adherence of monocytes]

Inducing lipid peroxidation injury to cultured EC from human umbilical vein was achieved by treating EC with diamide. When the concentration of diamide reached 0.1 x 10(-4) mol/l, intracellular accumulation of lipid peroxide and EC damage were induced and then increased adherence of monocyte to EC was observed. Monocytes appeared to prefer to adhere onto the surfaces and intercellular spaces of the injured EC. These results suggest that the increased adherence of monocytes to EC injured by lipid peroxidation may play an important role in atherogenesis.

The SXYQRL sequence in the cytoplasmic domain of TGN38 plays a major role in trans-Golgi network localization

The trans-Golgi network (TGN) plays a central role in protein sorting/targeting. TGN38 is an integral membrane protein confined mainly to the TGN. When the cytoplasmic 32-residue sequence of TGN38 was fused to the ecto- and transmembrane domains of glycophorin A (a surface protein), the resulting chimeric protein was localized to the TGN. Detailed mutagenesis of the 32-residue sequence revealed that the Ser, Tyr, and Leu residues at positions 23, 25, and 28, respectively, are essential for TGN localization. Further studies demonstrate that the sequence SXYQRL can by itself confer significant TGN localization.

Transmembrane topology of the mammalian KDEL receptor

The mammalian KDEL receptor is an integral membrane protein with seven hydrophobic regions. Fusion proteins comprising a 37-kDa N-glycosylation reporter fused downstream of amino-terminal fragments of the KDEL receptor with varying numbers of hydrophobic regions were synthesized in an in vitro translation system containing canine pancreatic microsomes. The luminal or cytosolic orientation of the reporter, and hence of the hydrophilic region to which it is fused, was inferred from the presence or absence of glycosylation, which occurs only in the lumen of the microsomes. The cytosolic orientation of the N and C termini was also confirmed immunocytochemically. Our results suggest that the KDEL receptor is inserted into the membrane with only six transmembrane domains and that both the amino and carboxy termini are located in the cytoplasm.

Protein trafficking along the exocytotic pathway

Proteins of the exocytotic (secretory) pathway are initially targeted to the endoplasmic reticulum (ER) and then translocated across and/or inserted into the membrane of the ER. During their anterograde transport with the bulk of the membrane flow along the exocytotic pathway, some proteins are selectively retained in various intracellular compartments, while others are sorted to different branches of the pathway. The signals or structural motifs that are involved in these selective targeting processes are being revealed and investigations into the mechanistic nature of these processes are actively underway.

Molecular cloning, characterization, subcellular localization and dynamics of p23, the mammalian KDEL receptor

We have isolated a cDNA clone (mERD2) for the mammalian (bovine) homologue of the yeast ERD2 gene, which codes for the yeast HDEL receptor. The deduced amino acid sequence bears extensive homology to its yeast counterpart and is almost identical to a previously described human sequence. The sequence predicts a very hydrophobic protein with multiple membrane spanning domains, as confirmed by analysis of the in vitro translation product. The protein encoded by mERD2 (p23) has widespread occurrence, being present in all the cell types examined. p23 was localized to the cis-side of the Golgi apparatus and to a spotty intermediate compartment which mediates ER to Golgi transport. A majority of the intracellular staining could be accumulated in the intermediate compartment by a low temperature (15 degrees C) or brefeldin A. During recovery from these treatments, the spotty intermediate compartment staining of p23 was shifted to the perinuclear staining of the Golgi apparatus and tubular structures marked by p23 were observed. These tubular structures may serve to mediate transport between the intermediate compartment and the Golgi apparatus.

[Eclampsia complicated with cerebrovascular disease]

Ten eclamptic patients complicated by acute cerebrovascular disease were admitted during the past eight years from Feb. 1982 to Feb. 1990. There were six cases of superior sagittal sinus thrombosis, two cases of cerebral hemorrhage, one cases of subarachnoid hemorrhage and the other one of cerebral infarction. Among them, eight patients were cured. Our analysis demonstrates that it is advisable to terminate pregnancy by cesarean section as soon as possible. A comprehensive management proposed by good cooperation between neurologist, neurosurgeon and obstetrician is the key to get a good way to cure these patients.

Age distribution and turnover of physicians in nonmetropolitan counties of the United States

Using data for 1975 to 1985 from the Area Resource File (ARF), net number changes in different age groups of physicians practicing in nonmetropolitan counties are examined. Small net increases are seen in the higher age groups in most county size categories but the most striking change is large increases in the age groups up to age 44. Family practitioners show a net decline in all county size categories for ages 45-54, but these are offset by increases in medical specialists. In counties of less than 25,000 population, the rate of turnover of physicians over the 1983-1988 period was 25 percent; physicians exiting these counties had a mean age of 52.3 years. The data indicate that aging of physicians in rural counties should not affect maintenance of current supply in the short run, but that increasing the physician-to-population ratio in areas with less adequate supply will be difficult, particularly if the rate of increase of younger physicians in nonmetropolitan counties does not continue.

Selective inhibition of protein targeting to the apical domain of MDCK cells by brefeldin A

Dipeptidyl peptidase IV (DPPIV) is mainly vectorially targeted to the apical surface in MDCK cells. BFA was found to abolish the apical targeting of DPPIV. This BFA effect could be achieved under conditions where the ER to Golgi transport and the total surface expression of DPPIV were essentially unaffected. BFA executed its effect during the transport from the trans-Golgi network (TGN) to the surface. The inhibition of apical targeting resulted in enhanced mis-targeting to the basolateral surface. The mistargeted DPPIV was transcytosed back to the apical domain only after BFA withdrawal. In contrast, the basolateral targeting of uvomorulin was unaffected by BFA. These results established that the apical targeting of DPPIV was selectively abolished by BFA.

Biochemical fractionation and characterization of proteins from Golgi-enriched membranes

Fractions enriched in Golgi membranes were prepared from rat liver by sucrose gradient ultracentrifugation. These enriched membranes were further subfractionated on the basis of their solubilities in EGTA, 150 mM sodium carbonate, pH 11.5, sodium deoxycholate, Triton X-100, or sodium dodecyl sulfate. This led to isolation of peripheral, luminal, and integral membrane proteins of the Golgi-enriched membranes. Luminal and membrane proteins were further purified by wheat germ agglutinin and concanavalin A lectin affinity chromatographies. Some proteins from these lectin columns were resolved by preparative gel electrophoresis and microsequenced. Subsequently, antibodies were produced for two proteins by immunization of either mice or rabbits. Immunofluorescence microscopy suggests that these proteins are confined to Golgi apparatus-like structures. The protocol described is well suited for the study of organelle structure and function.

The transmembrane domain of N-glucosaminyltransferase I contains a Golgi retention signal

The enzyme N-acetylglucosaminyltransferase I (NT, EC 2.4.1.101) is a resident type II transmembrane protein of the Golgi apparatus. To delineate the portion of its primary sequence that is responsible for the Golgi retention of this protein, we constructed chimeras containing different N-terminal portions of NT joined to a reporter sequence, the ectodomain of a type II surface membrane protein. These chimeric proteins were found to be retained in the Golgi apparatus as assessed by cell surface biotinylation and immunofluorescence. We found that the transmembrane domain of NT is sufficient to confer Golgi retention of the fusion proteins and propose that it contains the Golgi retention signal of the parent molecule.

Retention of a type II surface membrane protein in the endoplasmic reticulum by the Lys-Asp-Glu-Leu sequence

Soluble luminal proteins of the endoplasmic reticulum (ER) are known to be retained by a tetrapeptide retention signal, KDEL. We report in this communication that the KDEL sequence when appended to the carboxy terminus of a cell surface membrane protein, dipeptidyl peptidase IV (DPPIV), resulted in its retention in the endoplasmic reticulum of transfected Madin-Darby canine kidney cells as assessed by indirect immunofluorescence. Selective surface biotinylation revealed that about 90-95% of the expressed DPPIV was retained in the ER. Appendance of the sequence KDEV did not, however, result in ER retention, illustrating the functional specificity of the retention signal. The ER retention was not due to misfolding of the mutant protein, as the mutant proteins remained enzymatically active. Our data suggest that the KDEL receptor is able to recognize and recycle type II membrane proteins containing a carboxyl-terminal KDEL sequence and postulates the existence of such yet to be identified endogenous proteins.

The 17-residue transmembrane domain of beta-galactoside alpha 2,6-sialyltransferase is sufficient for Golgi retention

beta-Galactoside alpha 2,6-sialyltransferase (ST) is a type II integral membrane protein of the Golgi apparatus involved in the sialylation of N-linked glycans. A series of experiments has shown that the 17-residue transmembrane domain of ST is sufficient to confer localization to the Golgi apparatus when transferred to the corresponding region of a cell surface type II integral membrane protein. Lectin affinity chromatography of chimeric proteins bearing this 17-residue sequence suggests that these chimeric proteins are localized in the trans-Golgi cisternae and/or trans-Golgi network. Further experiments suggest that this 17-residue sequence functions as a retention signal for the Golgi apparatus.

Inhibition by brefeldin A of protein secretion from the apical cell surface of Madin-Darby canine kidney cells

The effect of brefeldin A (BFA) on total and polarized protein secretion was examined in MDCK cells. Increasing concentrations of BFA have increasingly inhibitory effects on total protein secretion. The total protein secretion was essentially unaffected by BFA at 0.5 microgram/ml. When the BFA concentration was increased to 10 and 30 micrograms/ml, the total protein secretion was reduced to about 70 and 25%, respectively, of the control level. Consistent with this effect on total protein secretion, the Golgi structure as revealed by C6-NBD-ceramide (a fluorescent ceramide analog) staining was essentially unaltered by 0.5 microgram/ml BFA, while 10 and 30 micrograms/ml BFA significantly dispersed the Golgi apparatus. When the polarity of protein secretion was examined, it was found that the ratio of proteins secreted from the apical to those from the basolateral surface was reduced from 1.5-2.0 to 0.4-0.7 by all three BFA concentrations. Furthermore, several proteins which are preferentially released from the apical surface were found to be released without apparent surface polarity, while several other proteins which were preferentially released from the basolateral surface were unaffected. This study suggests that BFA, at 0.5 microgram/ml, can selectively inhibit protein secretion from the apical surface without affecting total protein secretion. The inhibition of apical secretion results in enhanced protein secretion from the basolateral surface.

Evaluation of second-look laparotomy for ovarian cancer: second-look vs. serum CA125

Thirty patients with ovarian cancers underwent second-look operations in our hospital between 1981 and 1989, and the results were compared with serum CA125 values. The over-all positive rate determined by second-look laparotomy in the present series was 56.7% (17/30)-40% as gross and 17% an microscopic tumors. The result of the second-look was related to the staging and size of the residual tumor after the previous operation: 1/3 of stage I and II lesions and 16/27 of stage III and recurrent lesions were positive on second-look. The positive rates of those patients who were free from residual tumor and those with residual tumors less than or equal to 2 cm or greater than 2 cm were 28.6% (2/7), 60% (9/15) and 75% (6/8), respectively. Among the 23 patients assayed as to serum CA125 level before the second-look, 18 (78%) were within normal limits (less than 65 U/ml), including 12 patients (66.6%) who were second-look positive and 6 who were negative. Five patients with microscopic tumors and 3 patients with gross tumors less than or equal to 2 cm all had normal CA125 levels before the second-look. Among the 5 of 9 patients with gross tumors greater than 2 cm who had elevated CA125 levels, not one was found to be negative on second-look. This may imply that the elevated CA125 levels indicate recurrence, though a normal CA125 assay certainly does not preclude recurrence.

[Practical anatomy of the frontal and facial veins]

The frontal and facial veins of 15 adult cadavers were dissected. The main branch(es) of the frontal vein may be single (13.3%), dual (80.0%), or triple (6.7%). Blood from the veins around the orbit is collected by the venous sinus in the inner canthus, and the transverse dorsal nasal vein is a bridge between the venous sinuses of both sides. Therefore, veins around the orbit on both sides can be radiographed by venous puncture on either side. The facial vein is S-shaped and composed of 4 segments. Projective locations of the veins are described, with suggestions for practical clinical applications.

Identification and characterization of a murine receptor for galactose-terminated glycoproteins

The asialoglycoprotein receptor, the hepatic binding lectin for galactose-terminated glycoproteins, has been isolated and characterized from human, rabbit and rat liver. Several recent studies have shown the existence of the same receptor in murine liver. However, the biochemical structure of the receptor in murine liver has not been resolved. In this paper, we describe the identification and purification of the receptor for asialoglycoproteins from murine liver. The purified receptor has three polypeptides with apparent molecular weights of 42,000, 45,000 and 51,000, respectively, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Furthermore, our studies suggest that the receptor from murine liver is very similar to its counterpart in rat liver, although some potential interesting differences have also been observed. Initial studies indicate that this receptor is well conserved in different mouse strains.

cDNA cloning for a bile canaliculus domain-specific membrane glycoprotein of rat hepatocytes

Hepatocytes are polarized cells with distinct sinusoidal, bile canalicular, and basolateral plasma membrane domains. Each domain contains proteins that are specific for it. We have isolated three cDNA clones encoding a rat liver bile canaliculus domain-specific glycoprotein with Mr 110,000 (gp110) by immunologically screening a rat kidney lambda gt11 cDNA library with a rabbit polyclonal antiserum directed against purified gp110. The authenticity of these clones was verified as follows. (i) The antiserum recognizes specifically isopropyl beta-D-thiogalactoside-induced fusion proteins on electrophoretic transfer blots of total lysogen lysates containing these cDNA clones. (ii) Antibodies epitope-selected by these clones are able to interact with gp110 on electrophoretic transfer blots. (iii) The amino acid sequencing derived from the DNA sequence was confirmed by amino acid sequencing of a tryptic peptide of gp110. Rescreening of the same library with the cDNA clones identified a full-length cDNA clone for this glycoprotein. Sequence analysis indicates that the N-linked carbohydrate chains are concentrated on the N-terminal part of this highly glycosylated protein.