Lack of effect of simvastatin on insulin sensitivity in Type 2 diabetic patients with hypercholesterolaemia: results from a double-blind, randomized, placebo-controlled crossover study

AIMS

To evaluate the effects of simvastatin on serum lipids and insulin sensitivity in Type 2 diabetic patients with hypercholesterolaemia.

METHODS

A double-blind, randomized, placebo-controlled and two-period crossover study. After a 2-month run-in, 19 eligible Type 2 diabetic patients with hypercholesterolaemia were randomized to receive either simvastatin or placebo for 3 months, exchanging their treatment thereafter for another 3 months. Blood samples were taken in month 0 and at monthly intervals to measure serum lipids and indices of glycaemic control. An euglycaemic insulin clamp was performed in months 0, 3 and 6 to assess change of insulin sensitivity. The amount of glucose infused during 90-120 min of the clamp (M), and the mean values of serum insulin during 90-120 min (I) were measured. The M and M/I ratio were used to represent the in vivo insulin sensitivity of the subject.

RESULTS

Simvastatin significantly reduced serum total cholesterol (TC) by 23+/-18% and low density lipoprotein-cholesterol (LDL-C) by 30+/-26%. It did not alter glycaemic control. The M-values and M/I ratios were similar in both groups in each period and no drug effect on insulin sensitivity could be identified.

CONCLUSIONS

Simvastatin significantly reduced the serum TC and LDL-C levels without alteration of insulin sensitivity in Type 2 diabetic patients with hypercholesterolaemia.

Molecular characterization of the melanin-concentrating-hormone receptor

Orphan G-protein-coupled receptors (GPCRs) are cloned proteins with structural characteristics common to the GPCRs but that bind unidentified ligands. Orphan GPCRs have been used as targets to identify novel transmitter molecules. Here we describe the isolation from brain extracts and the characterization of the natural ligand of a particular orphan GPCR (SLC-1) that is sequentially homologous to the somatostatin receptors. We show that the natural ligand of this receptor is the neuropeptide melanin-concentrating hormone (MCH). MCH is a cyclic peptide that regulates a variety of functions in the mammalian brain, in particular feeding behaviour. We demonstrate that nanomolar concentrations of MCH strongly activate SLC-1-related pathways through G(alpha)i and/or G(alpha)q proteins. We have analysed the tissue localization of the MCH receptor and find that it is expressed in several brain regions, in particular those involved in olfactory learning and reinforcement mechanisms, indicating that therapies targeting the MCH receptor should act on the neuronal regulation of food consumption.

Tumor-suppressive activity of CD66a in prostate cancer

CD66a (human homolog of rat cell-cell adhesion molecule, also known as biliary glycoprotein) is a cell surface protein of the immunoglobulin family. CD66a has been shown to mediate homotypic cell adhesion. Aside from this, no other functions of this molecule have been demonstrated. We have observed previously that CD66a protein expression is lost in most prostate tumors, suggesting that the down-regulation of CD66a is associated with the abnormal growth of prostate cells. CD66a is homologous (65% identity) to rat cell-cell adhesion molecule, which has been shown to have tumor-suppressive activity. This homology suggests the possibility that CD66a might also be a tumor suppressor. In this report, we show that restoring CD66a expression in DU145 human prostate cancer cells by adenovirus (Ad)-mediated gene transfer dramatically altered the malignant phenotype of these cells, as evidenced by their reduced ability to form tumors in a xenograft animal model. This result suggests that loss of CD66a protein plays an important role in the development of prostate cancer, and that restoring CD66a expression might provide an effective treatment for prostate cancer. We further explored the possibility of using Ad vectors to deliver CD66a as a potential therapeutic agent for prostate cancer. Direct injection of Ad-CD66a, an Ad vector carrying the CD66a gene, into DU145 tumors in mice significantly suppressed the growth of these tumors. This antitumor activity of CD66a was found to be dose-dependent. These results suggest that CD66a has tumor-suppressive activity and that Ad-CD66a is a potential therapeutic agent for prostate cancer treatment.

Fungal corneal ulcers of onion harvesters in southern Taiwan

Fungal corneal ulcers related to agriculture has been reported throughout the world, especially in tropical areas. Most of them were sporadic and had histories of ocular trauma or use of topical corticosteroids and topical antibiotics. Five onion harvesters had fungal corneal ulcers during the same harvest period in Southern Taiwan. The authors think that this is the first report of a group occurrence relating to agricultural workers. Although all of the patients improved after medical and surgical management, their vision was greatly decreased. It is suggested that the tropical climate, the harvest procedure, the characteristic monsoon, and lack of eye protection were involved. Therefore, the importance of the eye protection, hygiene education, and improving medical care to reduce the occurrence of fungal corneal ulcer in agriculture workers must be emphasised.

C-CAM1 expression: differential effects on morphology, differentiation state and suppression of human PC-3 prostate carcinoma cells

Studies in rat prostate and liver have suggested that C-CAM1 is involved in the formation and maintenance of histotypic associations in tissues and possibly tumors. Most recently, C-CAM1 has been shown to suppress tumorigenicity of prostate and colon carcinoma cells. However, the mechanisms whereby C-CAM1 suppresses growth and the relationship of this activity to its proposed role in histotypic interactions remain largely unknown. In the present study, we have analysed the growth, phenotypic, morphological and ultrastructural characteristics of four human PC-3 prostate carcinoma cell lines transduced with C-CAM1 retrovirus. We report that three of four lines regained their tumorigenic phenotype in vivo while maintaining high levels of C-CAM1 expression and a growth retarded phenotype in vitro. These findings suggested that high levels of C-CAM1 expression were negatively influencing recovery during reconstitution after freezing or during the latency period after subcutaneous injection and that loss of suppression resulted from changes in expression of other molecules required for full disclosure of C-CAM1 mediated growth inhibition. Results from Northern blot and immunofluorescence analyses of tumor nodules demonstrated that C-CAM1 decreased rather than enhanced phenotypic differentiation and induced ultrastructural and morphological changes that occurred independently of tumor suppression.

Expression and androgen regulation of C-CAM cell adhesion molecule isoforms in rat dorsal and ventral prostate

C-CAM is an epithelial cell adhesion molecule with two major splice variants that differ in the length of the cytoplasmic domain. C-CAM1 (long (L)-form) strongly suppresses the tumorigenicity of human prostate carcinoma cells. In contrast, C-CAM2 (short (S)-form) does not exhibit tumor-suppressive activity. In the present study we have investigated the functional significance of L-form and S-form C-CAM in rat prostate by examining their expression and distribution in different prostate lobes and their response to androgen deprivation. RNase protection assays with a probe for both C-CAM isoforms detected high levels of C-CAM messages in the rat dorso-lateral prostate (DLP). L- and S-form proteins, localized by indirect immunofluorescence using isoform-specific antipeptide antibodies, were co-expressed on the apical surface of prostate epithelial cells in normal DLP. Androgen depletion did not significantly change the steady state levels of C-CAM message and protein expression in the DLP, although there was a change in the pattern of protein expression in these lobes. In contrast, C-CAM isoform messages and proteins were undetectable in normal ventral prostate (VP) but increased markedly in this lobe in response to castration, producing isoform ratios similar to those in DLP. These results demonstrate that coordinate expression of C-CAM isoforms is maintained in the VP following androgen depletion and suggest that androgen suppresses C-CAM expression in VP but not in DLP. These results suggest that balanced expression of L- and S-form C-CAM is important for normal prostate growth and differentiation.

Microtubule-associated protein-2 in the hypothalamo-neurohypophysial system: low-molecular-weight microtubule-associated protein-2 in pituitary astrocytes

Microtubule-associated protein-2 is the most abundant microtubule-associated protein in the brain and is responsible for morphogenesis and maintenance of the nervous system. In the present experiments, we have examined the localization of microtubule-associated protein-2 in the hypothalamo-neurohypophysial system of the rat using western blots and immunohistochemistry. Two monoclonal antibodies against microtubule-associated protein-2, antibody C and AP20, were used: antibody C recognizes both the high- and low-molecular-weight isoforms of microtubule-associated protein-2; antibody AP20 specifically detects high-molecular-weight microtubule-associated protein-2 only. Western blot analysis revealed expression of high-molecular-weight microtubule-associated protein-2 in the whole brain, hippocampus and whole hypothalamus. While the supraoptic nucleus expressed only high-molecular-weight microtubule-associated protein-2, the adult posterior pituitary predominantly expressed low-molecular-weight microtubule-associated protein-2, which was also seen in the embryonic whole brain. Light microscopic immunohistochemistry revealed that both antibody C and AP20 intensely stained dendrites of the dendritic and somatic zones in the supraoptic nucleus. Double labeling with antibodies against microtubule-associated protein-2 and oxytocin (or vasopressin) demonstrated that microtubule-associated protein-2 was localized in dendrites of magnocellular neurons in the supraoptic nucleus. In the posterior pituitary, however, antibody C stained fine processes and cell bodies of astrocytes, which were identified by an antibody against glial fibrillary acidic protein. Antibody AP20 also stained fine processes of some astrocytes in the posterior pituitary, but the intensity of immunoreactivity with antibody AP20 was weaker than that with antibody C. This result suggests that microtubule-associated protein-2 in astrocytes of the posterior pituitary is predominantly of the low-molecular-weight type. Moreover, western blots revealed low-molecular-weight microtubule-associated protein-2 of the posterior pituitary at a molecular weight slightly higher than embryonically expressed low-molecular-weight microtubule-associated protein-2, indicating that low-molecular-weight microtubule-associated protein-2 in the posterior pituitary is possibly the isoform microtubule-associated protein-2d. The present results demonstrate that astrocytes in the posterior pituitary of adult rats still retain the ability to express the immature variant of microtubule-associated protein-2, low-molecular-weight microtubule-associated protein-2, and its expression is probably linked to structural plasticity.

A New Expression for Multidimensional Franck-Condon Integrals

A new closed form expression for the Franck-Condon integrals for overlap between arbitrary multidimensional harmonic oscillators has been exactly derived by employing the generating functions method. The calculations lead to the deduction of some general rules whereby an arbitrary multidimensional Franck-Condon integral can be expressed as sums of products of the Hermite polynomials. Copyright 1999 Academic Press.

Function and therapeutic implication of C-CAM cell-adhesion molecule in prostate cancer

Human neoplasms are often caused by cumulative alterations in oncogenes and tumor-suppressor genes. By identifying the early genetic changes involved in tumorigenesis, one can develop strategies to prevent and detect cancers at early stages, when treatment is most effective. C-CAM1, a cell-adhesion molecule (CAM) isoform (I), was recently shown to play a critical role in prostate cancer initiation and progression. Loss of C-CAM1 expression occurs early in the development of prostate cancer, suggesting that C-CAM1 may help maintain the differentiated state of the prostate epithelium. Reintroduction of C-CAM1 into cancer cells can reverse their cancerous growth. Thus, the C-CAM1 molecule itself or drugs that increase C-CAM1 expression are promising agents for prostate cancer treatment. The mechanisms by which C-CAM1 suppresses tumorigenesis are different from those of p53 and Rb. Therefore, C-CAM1 therapy is a new form of prostate cancer treatment. To exploit C-CAM1's therapeutic potential, a human C-CAM1 adenovirus expression vector (Ad-hu-C-CAM1) has been used to treat prostate tumor xenografts in nude mice. The preliminary results have shown great promise. In addition, while C-CAM gene therapy may have immediate application in prostate cancer treatment, the knowledge to be learned from mechanistic studies of C-CAM1-mediated tumor suppression may also help us design better strategies for prevention and treatment for prostate cancer.

Schedule-dependence of C-CAM1 adenovirus gene therapy in a prostate cancer model

BACKGROUND

C-CAM1 functions as a tumor suppressor in prostate cancer. Thus C-CAM1 recombinant adenovirus therapy may be a promising treatment for prostate cancer. Understanding the time course of C-CAM1's antitumor activity is essential for designing an optimal schedule for C-CAM1 gene therapy.

MATERIALS AND METHODS

PC3 cells were exposed to Ad-C-CAM1 and the time course of C-CAM1 expression was monitored by flow cytometry. Tumors generated in nude mice by subcutaneous injection of PC-3 cells were used for in vivo testing of C-CAM1's antitumor activity. Intratumoral injections of viruses (either Ad-C-CAM1 or Ad-beta-gal) or buffer only (control) were performed according to two different schedules. Mice in Schedule A received a single injection, while mice in Schedule B received the same total amount of viruses in 3 equal doses at 2-week intervals.

RESULTS

After single exposure to Ad-C-CAM1, PC-3 cells expressed abundant C-CAM1 protein which reached the highest level on day 3 and persisted for up to 5 days. PC-3 tumors in nude mice exhibited 2 to 3-week lag in tumor growth curves after a single Ad-C-CAM1 injection. In contrast, 14 of the 18 tumors receiving 3 fractionated Ad-C-CAM1 injections regressed completely, while the other 4 tumors shrank to significantly smaller sizes.

CONCLUSIONS

Sustained expression of C-CAM1 is required for optimal tumor suppression. The schedule-dependence of C-CAM1's antitumor activity should be taken into account in optimizing gene therapy in clinical settings.

The light chain of CD98 is identified as E16/TA1 protein

The 80/40-kDa CD98 protein complex was purified using an anti-CD98 heavy chain monoclonal antibody coupled to Sepharose beads. Eluted proteins were subjected to preparative SDS-polyacrylamide gel electrophoresis, and protein corresponding to the 40-kDa CD98 light chain was excised. Following proteolysis with trypsin, a peptide fragment was sequenced by mass spectrometry. The nine residues obtained were identical to established C-terminal sequences of the human E16 and rat TA1 proteins, suggesting that TA1/E16 protein is the CD98 light chain. Consistent with this, anti-TA1/E16 antibodies specifically immunoblotted the approximately 35-40-kDa light chain present upon immunoprecipitation of the human CD98 complex. Furthermore, anti-CD98 heavy chain antibody specifically co-immunoprecipitated hemagglutinin-tagged light chain from cells transfected with hemagglutinin-tagged E16 cDNA. In conclusion, the CD98 light chain is identical to the TA1/E16 protein, based on partial amino acid sequence identity, antibody cross-reactivity, genetic reconstitution evidence, similar molecular size, and comparable cell distribution.

Evidence that endothelin-1 (ET-1) inhibits insulin-stimulated glucose uptake in rat adipocytes mainly through ETA receptors

The specificity of endothelin (ET) receptors involved in the inhibition of insulin-stimulated glucose uptake (ISGU) in rat adipocytes was investigated. Adipocytes were isolated from the epididymal fat pads of Sprague-Dawley rats. To determine receptor subtypes, we used three ET isopeptides, ET-1 and ET-2, both of which are nonselective agonists, and ET-3, a selective agonist for ETC receptors, to displace [125I]ET-1 binding from the fat cells. The efficiency of displacement was ET-1 > ET-2 >> ET-3, indicating that the primary receptors involved belonged to the ETA subtype. At an equal concentration of 1 micromol/L, BQ-610, a selective ETA antagonist, displaced [125I]ET-1 from binding to fat cells, whereas IRL-1038, a selective ETB antagonist, did not. Using [3H]2-deoxy-D-1-glucose ([3H]2-DG) as a tracer in studies of glucose uptake, we found that equimolar BQ-610 completely reversed the inhibitory effect of ET-1 on ISGU, whereas IRL-1038 was ineffective. Northern blot analysis of adipocyte receptors showed abundant mRNA for ETA, but no ETB subtype. These results clearly demonstrate that ETA is the predominant receptor in rat adipocytes.

Acute hyponatremia in the perioperative period: insights into its pathophysiology and recommendations for management

Our purpose is to review the topic of acute postoperative hyponatremia by focusing on pertinent aspects of the physiology of water and solute excretion. Four areas will be highlighted: an examination of the source of addition of electrolyte-free water, an exploration of the basis for the very large natriuresis that occurs during cerebral salt wasting following neurosurgery, possible reasons to explain why acute postoperative hyponatremia may pose a greater risk for young women [Ayus and Arieff 1996, Ayus et al. 1992, Arieff 1986, Wijdick et al. 1991], and issues related to treatment of acute hyponatremia.

Comparison of the expression of two immediate early gene proteins, FosB and Fos in the rat preoptic area, hypothalamus and brainstem during pregnancy, parturition and lactation

Medial preoptic area (MPA), supraoptic nucleus (SON), magnocellular (MaPVN) and parvocellular (PaPVN) paraventricular hypothalamic nuclei, and mesencephalic lateral tegmentum (MLT) are involved in maternal behavior, parturition and lactation. This study investigated the FosB and Fos immunoreactivity in these regions of virgin, pregnant, parturient, lactating, and lactating-arrested rats. The patterns of FosB and Fos expression were compared between the sections taken from the same animals. Quantitative immunohistochemistry revealed a significant increase in the numbers of FosB-positive neurons in the MPA, SON, MaPVN, and MLT of parturient and lactating females as compared with pregnant or virgin animals. In lactating rats, the numbers of FosB-positive neurons in the MPA, PaPVN, and MLT were increased, but the numbers in the SON and MaPVN were decreased as compared with parturient females. Many Fos-positive neurons were also seen in parturient and lactating rats, and the patterns of Fos expression in each region were quite similar to those of FosB. Moreover, double-labeling immunohistochemistry revealed that: (1) many FosB-positive nuclei were observed in oxytocin and vasopressin neurons of the SON and PVN in parturient rats; (2) within FosB-positive neurons, 89.5% in the MPA, 86.8% in the MLT of parturient rats, and 92% in the MPA and 90.8% in the MLT of lactating animals were also Fos-positive. Only a small number of FosB and Fos-positive neurons were seen in females that were killed in the early stage of parturition. Removal of the litters immediately after parturition completely eliminated FosB and Fos expression in each region in the dams. Taken together, the present results suggest that FosB expression is co-involved with Fos in the neural activation during parturition and lactation in rats.

Characterization of BRCA2: temperature sensitivity of detection and cell-cycle regulated expression

People carrying a mutant BRCA2 gene are susceptible to breast, ovarian, pancreatic and other tumors. Many facets of BRCA2 have been studied, including its mutation in human cancers, its role in mouse embryogenesis and its RNA expression in different tissues and different mouse embryogenesis stages. However, there has been very little characterization of BRCA2 protein. We investigated the biochemical and biological properties of BRCA2 by using a monoclonal antibody we generated against the N-terminal portion of BRCA2. We discovered that the detection of BRCA2 by immunoblot analysis was sensitive to the temperature used to denature the samples before gel electrophoresis. BRCA2 was easily detectable when samples were denatured at low temperature instead of boiling. Although the precise mechanism underlying this observation is not clear yet, this finding will significantly improve our ability to study BRCA2. We examined the expression of BRCA2 using an immunoblot analysis protocol modified according to this observation. We showed that BRCA2 was presented in every human cell lines examined, including Capan-1, which expressed a truncated BRCA2 due to a BRCA2 frameshift mutation. We also showed that the expression of BRCA2 was cell-cycle regulated. Our results suggest that BRCA2 has an important role in cell growth regulation.

Anesthetic management of a parturient with Eisenmenger's syndrome and preeclampsia during cesarean section--a case report

It has been recommended that women with Eisenmenger's syndrome (ES) are better not to become pregnant and pregnancy may justifiably be terminated by artificial abortion to avoid high maternal mortality and coherent fetal mortality. We present a case report about a parturient with ventricular septal defect (VSD) and ES who received general anesthesia for Cesarean section (C/S) because of preeclampsia, as a result of which she finally succumbed to an episode of intraoperative hypotension in spite of vigorous cardiopulmonary resuscitation. The death was thought to be precipitated by continuous deterioration of maternal health during the 3rd trimester of gestation. The anesthetic management of pregnant ES patients in confinement was reviewed and discussed, and the possible etiological factors relevant to the tragic outcome were also explored.

Prediction of dry weight through changes in blood volume and plasma cyclic 3',5'-guanosine monophosphate in patients under maintenance hemodialysis

Dry weight evaluation is generally made from clinical observation of body weight (BW) changes, edema, blood pressure, and chest radiograph. In fact, 25-50% of patients on chronic hemodialysis had an incorrectly determined dry weight. To predict dry weight, twenty stable patients on regular hemodialysis were enrolled to investigate the correlation among dry weight, hematocrit, blood volume (BV), and vasoactive hormones including plasma renin activity (PRA), aldosterone (PA), and cyclic 3',5'-guanosine monophosphate (cGMP) values. BV was estimated by an infrared light reflection method. PRA, PA, and plasma cGMP were determined by commercial radioimmunoassay kits. The results showed significantly decreasing plasma cGMP values toward the end of hemodialysis compared with before hemodialysis (15.76 +/- 3.56 pmol/ml vs 33.57 +/- 3.98 pmol/ml; p < 0.05). A significant correlation exists between changes in plasma cGMP values and BV (p < 0.05). In addition, no significant correlation exists between changes in plasma cGMP and BW. A good correlation was found between changes in BV and hematocrit throughout dialysis (r = -0.774; p < 0.001). PRA and PA values predict neither BV nor BW changes. All patients were treated to attain a further ultrafiltration of 0.5 to 1.0 L after reaching dry weight, and we found that the critical point in blood pressure drop occurred when BV decreased by 8% or when plasma cGMP values decreased by 50% from their initial values. Continuous BV monitoring with infrared light reflection and detecting of cGMP throughout hemodialysis could help predict dry weight and avoid dialysis hypotension.

Isolation and characterization of PAGE-1 and GAGE-7. New genes expressed in the LNCaP prostate cancer progression model that share homology with melanoma-associated antigens

The LNCaP progression model of human prostate cancer consists of lineage-related sublines that differ in their androgen sensitivity and metastatic potential. A differential display polymerase chain reaction was employed to evaluate mRNA expression differences between the LNCaP sublines in order to define the differences in gene expression between the androgen-sensitive, nontumorigenic LNCaP cell line and the androgen-insensitive, metastatic LNCaP sublines, C4-2 and C4-2B. An amplicon, BG16.21, was isolated that showed increased expression in the androgen-independent and metastatic LNCaP sublines, C4-2 and C4-2B. Hybridization screening of a lambda gt11 expression library with BG16.21 revealed two transcripts, both homologous to BG16.21 at the 3' end. A GenBankTM data base search using the GCG Wisconsin software package revealed the shorter approximately 600-bp transcript (designated GAGE-7) to be a new member of the GAGE family. The second approximately 700-bp transcript was a novel gene (designated PAGE-1, "prostate associated gene") with only 45% homology to GAGE gene family members. RNA blot analysis demonstrated that GAGE-7 mRNA was expressed at equal levels in all lineage related prostate cancer cell sublines, while PAGE-1 mRNA levels were elevated 5-fold in C4-2 and C4-2B as compared with LNCaP cells. Neither GAGE-7 nor PAGE-1 demonstrated any regulation by androgens in the prostate cancer cell lines used in this study. PAGE-1 and GAGE-7 expression was found to be restricted to testes (high) and placenta (low) on human multiple tissue Northern blots. As GAGE/MAGE antigens were reported previously to be targets for tumor-specific cytotoxic lymphocytes in melanoma, these results suggest that PAGE-1 and GAGE-7 may be related to prostate cancer progression and may serve as potential targets for novel therapies.

Physiological disposal of the potential alkali load in diet of the rat: steps to achieve acid-base balance

The purpose of this study was to provide a better understanding of the physiological role of endogenous net organic acid production in rats consuming their usual diet. Balance studies were performed over 24 h, and urine was collected in the day and night portions of the diurnal cycle. A supplemented low-electrolyte diet(LED) was fed to determine whether urinary organic anions were identical to those in the diet. A titration procedure was developed to determine the pK of titratable groups in the urine of rats studied with and without an acid load. Although normal rats excreted net acid (NAE), the latter was inversely related to the amount of food consumed. The rates of excretion of bicarbonate (HCO3), citrate, unmeasured organic anions, and NH+4 were higher in the night portion of the diurnal cycle. NAE rose dramatically when alkali intake was decreased by consuming the LED. Dietary and urinary organic anions were not identical because rats fed the LED supplemented with potassium citrate excreted <10% of this alkali load as citrate and <25% as HCO3. In the 24 h after 3,000 ¿mol NH4Cl was given intraperitoneally, H+ did not appear to be retained, yet NAE rose by only close to 2,000 ¿eq. The rate of excretion of titratable groups with a pK in the 3 to 5 pH range fell by close to 1,000 ¿eq; most of these changes occurred in the first 7 h after NH4Cl was given. We conclude that rat chow provides a large net alkali load. There appear to be two types of endogenous acid production, a form associated with a rise in NAE (e.g., sulfuric acid) and dietary alkali-driven endogenous net acid production, which titrates this alkali. Renal excretion of organic anions makes these acids end products of metabolism.

The neuromuscular effects of mivacurium in adults with priming technique during nitrous oxide-fentanyl anesthesia: a randomized comparative study with succinylcholine

BACKGROUND

We investigated the neuromuscular effects of equipotent dose (3 x ED90) of mivacurium either given as a single bolus or under the influence of priming technique, comparing with that of succinylcholine in adults undergoing elective surgery during nitrous oxide-narcotic anesthesia.

METHODS

Sixty ASA class I patients of either sex with age between 16 to 49 years were randomly assigned to 3 groups for a trial of mivacurium under nitrous oxide-narcotic anesthesia. Group I (non-priming group, n = 20) received mivacurium 0.25 mg/kg straight as a single intubating dose; Group II (priming group, n = 20) received an intubating dose of 0.225 mg/kg mivacurium which was preceded by 0.025 mg/kg 3 min earlier; and Group III received an intubating bolus of succinylcholine 1 mg/kg. Thenar electromyogram response to supramaximal train-of-four stimulation of the ulnar nerve at 12-s intervals was used to determine neuromuscular blockade. Blood pressure and heart rate were recorded before and at 1-min interval for 3 min after injection of drugs. Data were presented as mean +/- standard deviation. P value < 0.05 was considered statistically significant.

RESULTS

The onset time of mivacurium was accelerated by priming procedure in comparison with the nonpriming technique (2.0 min vs. 2.7 min), but it was much slower than that of succinylcholine (0.8 min). The priming procedure did not influence the duration of action or recovery. Side effects of mivacurium, such as cutaneous flushing and hypotension, were minimal at this dose in our patients.

CONCLUSIONS

Priming technique (with 10% of the total dose as the priming dose, and 3 min as the priming interval) can hasten the onset of mivacurium in adults during nitrous oxide-narcotic anesthesia without influencing the duration of action and recovery time.

Disassociation of sigma subunit from RNA polymerase of Xanthomonas oryzae pv. oryzae by phage Xp10 infection

The sigma subunit of Xanthomonas oryzae pv. oryzae is disassociated from host RNA polymerase after phage Xp10 infection. To clarify the possible mechanism for this observation, sigma subunit was purified and an antiserum against sigma subunit was prepared. Immunoprecipitation of RNA polymerase by the anti-core RNA polymerase antiserum, followed by immunoblotting with anti-sigma subunit antibody, revealed that sigma subunit was lost from RNA polymerase within 10 minutes after Xp10 infection. Loss of sigma subunit was not observed under other stress conditions including heat and cold stress, starvation and growth to stationary phase. Two-dimensional immunoblotting analysis did not reveal any covalent modification of either sigma subunit or RNA polymerase after Xp10 infection. These results suggest that separation of th subunit from RNA polymerase may be due to competition with other binding factors.

Demonstration of adhesion activity of the soluble Ig-domain protein C-CAM4 by attachment to the plasma membrane

The carcinoembryonic antigen (CEA) family is a large group of proteins with immunoglobulin (Ig)-like structures. The membrane-associated CEA-family proteins have been shown to mediate intercellular adhesion. In addition to these membrane-associated proteins, several secreted CEA-like proteins, such as C-CAM4, PSG1b, and PSG11s, have also been identified. The functions of these soluble proteins are not clear because they cannot support intercellular adhesion like the membrane-associated proteins can. A fundamental question important for understanding the functions of these soluble proteins is whether they can interact in a homophilic fashion as do many of their membrane-associated homologues. We found that the homophilic interactions between these soluble proteins were too weak to be detected by solution binding assays. This is not unexpected because interactions between adhesion molecules are usually transient and weak to allow for control of association and dissociation. By expressing these soluble CEA-family proteins, C-CAM4, PSG1b, and PSG11s, as membrane-anchored forms, we showed that C-CAM4 could mediate intercellular adhesion, whereas PSG1b and PSG11s, despite their 52% identity to C-CAM4, could not. These results suggest that C-CAM4, but not PSG1b and PSG11s, can probably form homodimers. Thus, these secretory CEA-family members most likely have different interaction mechanisms, i.e., C-CAM4 might function as dimers, while PSGs might function as monomers.