Evidence for association of an ATP-stimulatable Ca(2+)-independent phospholipase A2 from pancreatic islets and HIT insulinoma cells with a phosphofructokinase-like protein

Glucose-induced insulin secretion from pancreatic islets requires metabolism of glucose within islet beta-cells, and ATP has attracted interest as a messenger of glucose metabolism within beta-cells. Glucose-induced insulin secretion from islets and HIT insulinoma cells is accompanied by activation of an ATP-stimulatable Ca(2+)-independent phospholipase A2 (ASCI-PLA2) enzyme, the catalytic activity of which resides in a 40 kDa protein. An analogous PLA2 enzyme in myocardium was recently found to consist of a complex of a 40 kDa catalytic protein with a tetramer of an isoform of the glycolytic enzyme phosphofructokinase (PFK). Association of the PFK isoform with the myocardial PLA2 catalytic protein was found to confer ATP sensitivity onto the enzyme complex. Here we demonstrate that the majority of HIT cell and islet ASCI-PLA2 catalytic activity elutes from a gel filtration column in a region corresponding to 400 kDa, suggesting that the 40 kDa beta-cell ASCI-PLA2 catalytic protein exists as part of a larger molecular mass complex. Islet and HIT cell ASCI-PLA2 activities were immunoprecipitated by antibodies directed against PFK, and the immunoprecipitates contained 40 and 85 kDa proteins which correspond to the molecular masses of the PLA2 catalytic protein and of a PFK monomer, respectively. Islet and HIT cell ASCI-PLA2 activities were selectively and reversibly adsorbed to affinity matrices containing immobilized PFK but not to similar matrices containing immobilized transferrin or bovine serum albumin. Addition of free PFK prevented binding of HIT cell ASCI-PLA2 activity to immobilized PFK matrices and promoted desorption of activity previously bound to such matrices. These results suggest that beta-cell ASCI-PLA2, like the myocardial enzyme, exists as a complex comprised of a catalytic protein and a PFK-like protein and raise the possibility that the ASCI-PLA2 complex may represent a component of the beta-cell glucose sensor, which links glycolysis, phospholipid hydrolysis, and membrane electrochemical events involved in glucose-induced insulin secretion.

Signal transduction pathways induced by heregulin in MDA-MB-453 breast cancer cells

Heregulins (HRGs) induce tyrosine phosphorylation of several members of the erb-B family of receptors. Although originally isolated as the ligands for p185c-erb-2, recent evidence suggests that other receptors of the erbB family, including p180erbB-3 and p180erbB-4, are their true cognate receptors. Stimulation of MDA MB-453 cells with HRG beta 2 resulted in the tyrosine phosphorylation of p185c-erbB-2 and p180erbB-4 in a time- and dose-dependent fashion. This event was accompanied by the formation of multimeric complexes between the activated receptors and SH2-containing proteins. Ligand caused p120-rasGTPase activating protein (GAP), SHC and the p85 subunit of phosphatidylinositol-3'-kinase (PI3K) to be associated with both p185c-erbB-2 and p180erbB-4. In addition, tyrosine phosphorylation of p85-PI3K and SHC, but not of GAP or of its associated p62 and p190 proteins, was also detected. HRG also induced the association of GRB2 with tyrosine phosphorylated p185c-erbB-2, p180erbB-4 and SHC. Activation of mitogen-activated protein kinase (MAPK) ( > 30-fold over untreated controls) was observed upon receptor(s) activation, as it was the induction of the immediate early gene c-fos ( > 200-fold). These observations suggest that p21ras activation plays a role in the HRG pathway. Furthermore, comparative analysis of the binding of p85-PI3K to 185c-erbB-2 and p180erbB-4, revealed a preferential association with activated p180erbB-4. These findings might suggest a model of HRG action in which the relative expression of the various erb-B family members and the partitioning of signal transduction molecules between each type of receptor might determine the nature of the signal elicited by the ligand and the biological response attained.

Role of altered beta-adrenoceptor signal transduction in the pathogenesis of cirrhotic cardiomyopathy in rats

BACKGROUND & AIMS

Attenuated ventricular contractility has been documented in cirrhosis, but the pathogenesis remains unclear. The beta-adrenergic receptor system is critical in modulating cardiac contraction. Therefore, the aim of this study was to clarify beta-adrenoceptor signaling function in a rat model of cirrhosis.

METHODS

Cirrhosis was induced by bile duct ligation, whereas controls underwent a sham operation. Myocardial contractility was studied by measuring isolated left ventricular papillary muscle contraction under isoproterenol stimulation. Beta-Adrenoceptor signaling was evaluated by measuring adenosine 3',5'-cyclic monophosphate generation after stimulation with isoproterenol, sodium fluoride, and forskolin. Guanosine triphosphate-binding protein expression from ventricular plasma membranes was determined by Western blots to measure G(s)alpha, Gi2alpha, and G(common)beta, respectively.

RESULTS

Maximum papillary muscle contractile responses in control and cirrhotic rats were 113% +/- 3% and 70% +/- 2% of basal, respectively (P<0.01), with no significant differences in the dose-inducing half-maximal response. Adenosine 3', 5'-cyclic monophosphate generation after stimulation with all three agents was significantly lower in cirrhotic compared with control rat membranes. G(s)alpha and Gi2alpha expression was significantly reduced in cirrhotics compared with controls, but G(common)beta expression remained unchanged.

CONCLUSIONS

These data showed cardiac contractile impairment in cirrhosis, associated with altered beta-adrenergic receptor signaling function and guanine nucleotide-binding protein expression. These factors may play an important role in the pathogenesis of cirrhotic cardiomyopathy.

The continuing increase in adenocarcinoma of the uterine cervix: a birth cohort phenomenon

BACKGROUND

Adenocarcinoma of the uterine cervix has been reported to be increasing among young white women and earlier studies suggest a birth cohort pattern for the observed increase. No study, however, has examined the time trends of adenocarcinoma of the cervix by birth cohort.

METHODS

Using Surveillance, Epidemiology, and End Results (SEER) data through 1990, the current study is designed to examine the time trends of invasive adenocarcinoma by birth cohort. An age-period-cohort model was fitted to the annual-age-specific rates to identify the components of birth cohort and time period as determinants of the observed time trends.

RESULTS

The results from this study clearly show that invasive adenocarcinoma of the uterine cervix has been increasing in both whites and blacks, but the increase is statistically significant only among whites, reaching 4.2 percent per year for those born since 1935. The results also show that the recent increase in invasive adenocarcinoma started among those born around the mid 1920s, and a strong birth cohort effect is largely responsible for the observed increase.

CONCLUSION

Invasive adenocarcinoma of the uterine cervix is increasing among recent birth cohorts. Analytical epidemiological studies are urgently needed to explore the risk factors responsible for the increase. The time trends for adenocarcinoma of the cervix should also be carefully monitored in the coming years.

Characterization of the sphingomyelin content of isolated pancreatic islets. Evaluation of the role of sphingomyelin hydrolysis in the action of interleukin-1 to induce islet overproduction of nitric oxide

Inflammatory cytokines may participate in the destruction of pancreatic islets during the pathogenesis of insulin-dependent diabetes mellitus, and the cytokine interleukin-1 (IL-1) strongly inhibits insulin secretion from rat pancreatic islets by a process which involves induction of expression of the inducible isoform of nitric oxide synthase and the overproduction of nitric oxide. The signaling events between IL-1 receptor occupancy and induction of nitric oxide synthase in rat islets involve activation of the transcriptional activator NFkappa B. Because sphingomyelin hydrolysis has been implicated as a signaling process both in NFkappa B activation and in IL-1 action in some cells, we have examined the potential involvement of sphingomyelin hydrolysis in the induction of islet nitric oxide overproduction by IL-1. Rat islet sphingomyelin pools were radiolabeled with [3H]choline, and sphingomyelin was then isolated by normal phase HPLC. Electrospray ionization-mass spectrometric analysis revealed islet sphingomyelin consists of at least 4 distinct molecular species, and the most abundant of them contained sphingosine as the long chain base and a residue of palmitic acid as the fatty acid substituent. Molecular species containing residues of stearic acid and arachidic acid were also observed. Neither interleukin-1 nor tumor necrosis factor-alpha was found to induce hydrolysis of islet sphingomyelin species, and neither an exogenous, cell-permeant ceramide species (N-acetyl-D-sphingosine) nor exogenous sphingomyelinase mimicked or potentiated the effect of IL-1 to increase rat islet nitric oxide generation, as reflected by nitrite production. Similar findings were obtained with RINm5F insulinoma cells and with mouse pancreatic islets. These findings provide the first information on the molecular species of sphingomyelin in pancreatic islets and suggest that sphingomyelin hydrolysis is not involved in the signaling pathway whereby IL-1 induces the overproduction of nitric oxide by pancreatic islets.

Continuing increase in incidence of germ-cell testis cancer in young adults: experience from Connecticut, USA, 1935-1992

The current study is designed to examine long-term trends by histologic types of testis cancer in Connecticut. A regression model was used to identify age, period, or cohort as determinants of the time-trend on histologic types of testis cancer. The results from this descriptive epidemiologic study show that the overall age-adjusted incidence rate of testis cancer has increased 3.5-fold in Connecticut during the past nearly 60 years of cancer registration. The rates for seminoma and non-seminoma have been increasing since the mid-1950s and increase in a similar manner for those aged 15 to 49. The largest increase was observed in the age groups 20 to 44 for seminoma and 15 to 34 for non-seminoma. The observed increase was limited to whites. The results from age-period-cohort modeling suggest that the observed increase in seminoma before 1950s could be largely attributable to a period effect, while the increase for cohorts born after about 1910 both for seminoma and for non-seminoma are mainly explained by a strong birth-cohort effect. Therefore, the observed increase in germ-cell testis cancer in this population is likely to continue in the coming years. Thus far, the proposed hypotheses, such as exposure to DES in utero, earlier lifetime exposure to viruses, trauma or unusual amounts of heat to the testis, cannot adequately explain the observed incidence patterns of testis cancer. Analytical epidemiologic studies with large sample size are urgently needed to examine the risk factors responsible for the increase.

[Video assisted thoracoscopic major lung resection]

We report the combined experience on video assisted thoracoscopic (VAT) anatomical lung resection from two hospitals in Hong King. 60 patients successfully underwent VAT anatomical lung resections: 55 lobectomies, 2 bi-lobectomies, 2 pneumonectomies and 1 segmectomy. There was no mortality. Intraopeative complication occurred in 1 patient due to malfunctioning of a vascular stapler. Postoperative complications were few. Average postoperative hospital stay was 7.2 days. Compared with the conventional thoracotomy approach, the VAT approach was associated with the conventional thoracotomy approach, the VAT approach was associated with significantly less analgesic requirement. We conclude that VAT anatomical lung resection is technically feasible. Specific complications, however, exist. The true role of this new approach in thoracic surgery awaits further study.

Interleukin-1 enhances pancreatic islet arachidonic acid 12-lipoxygenase product generation by increasing substrate availability through a nitric oxide-dependent mechanism

Interleukin-1 (IL-1) impairs insulin secretion from pancreatic islets and may contribute to the pathogenesis of insulin-dependent diabetes mellitus. IL-1 increases islet expression of nitric oxide (NO) synthase, and the resultant overproduction of NO participates in inhibition of insulin secretion because NO synthase inhibitors, e.g. NG-monomethyl-arginine (NMMA), prevent this inhibition. While exploring effects of IL-1 on islet arachidonic acid metabolism, we found that IL-1 increases islet production of the 12-lipoxygenase product 12-hydroxyeicosatetraenoic acid 12-(HETE). This effect requires NO production and is prevented by NMMA. Exploration of the mechanism of this effect indicates that it involves increased availability of the substrate arachidonic acid rather than enhanced expression of 12-lipoxygenase. Evidence supporting this conclusion includes the facts that IL-1 does not increase islet 12-lipoxygenase protein or mRNA levels and does not enhance islet conversion of exogenous arachidonate to 12-HETE. Mass spectrometric stereochemical analyses nonetheless indicate that 12-HETE produced by IL-1-treated islets consists only of the S-enantiomer and thus arises from enzyme action. IL-1 does enhance release of nonesterified arachidonate from islets, as measured by isotope dilution mass spectrometry, and this effect is suppressed by NMMA and mimicked by the NO-releasing compound 3-morpholinosydnonimine. Although IL-1 increases neither islet phospholipase A2 (PLA2) activities nor mRNA levels for cytosolic or secretory PLA2, a suicide substrate which inhibits an islet Ca(2+)-independent PLA2 prevents enhancement of islet arachidonate release by IL-1. IL-1 also impairs esterification of [3H8]arachidonate into islet phospholipids, and this effect is prevented by NMMA and mimicked by the mitochondrial ATP-synthase inhibitor oligomycin. Experiments with exogenous substrates indicate that NMMA does not inhibit and that the NO-releasing compound does not activate islet 12-lipoxygenase or PLA2 activities. These results indicate that a novel action of NO is to increase levels of nonesterified arachidonic acid in islets.

Automated system for detailed measurement of respiratory mechanics

OBJECTIVE

The mechanical properties of the respiratory system (i.e., elastance and resistance) depend on the frequency, tidal volume, and shape of the flow waveform used for forcing. We developed a system to facilitate accurate measurements of elastance and resistance in laboratory and clinical settings at the frequencies and tidal volumes in the physiologic range of breathing.

METHODS

A personal computer (PC) is used to drive a common clinically used ventilator while simultaneously collecting measurements of airway flow, airway pressure, and esophageal pressure from the experimental subject or animal at different frequencies and tidal volumes. Analysis analogous to discrete Fourier transform at the fundamental frequency (i.e., ventilator setting) is used to calculate elastances and resistances of the total respiratory system and its components, the lungs and the chest wall. We have shown that this analysis is independent of the high-frequency harmonics that are present in the waveform from clinical ventilators.

RESULTS

The system has been used successfully to make measurements in anesthetized/paralyzed dogs and awake or anesthetized human volunteers in the laboratory, and in anesthetized human volunteers in the laboratory, and in anesthetized humans in the operating room and intensive care unit. Elastances and resistances obtained with this approach are the same as those obtained during more controlled conditions, e.g., sinusoidal forcing.

CONCLUSIONS

Accurate, standardized measurements of lung and chest wall properties can be obtained in many settings with relative ease with the system described. These properties, and their frequency and tidal volume dependences in the physiologic range, provide important information to aid in the understanding of changes in respiratory function caused by day-to-day conditions, clinical intervention and pathologies.

A peptidomimetic inhibitor of farnesyl:protein transferase blocks the anchorage-dependent and -independent growth of human tumor cell lines

Farnesyl protein transferase (FPTase) catalyzes the first of a series of posttranslational modifications of Ras required for full biological activity. Peptidomimetic inhibitors of FPTase have been designed that selectively block farnesylation in vivo and in vitro. These inhibitors prevent Ras processing and membrane localization and are effective in reversing the transformed phenotype of Rat1-v-ras cells but not that of cells transformed by v-raf or v-mos. We have tested the effect of the FPTase inhibitor L-744,832 (FTI) on the anchorage-dependent and -independent growth of human tumor cell lines. The growth of over 70% of all tumor cell lines tested was inhibited by 2-20 microM of the FTI, whereas the anchorage-dependent growth of nontransformed epithelial cells was less sensitive to the effects of the compound. No correlation was observed between response to drug and the origin of the tumor cell or whether it contained mutationally activated ras. In fact, cell lines with wild-type ras and active protein tyrosine kinases in which the transformed phenotype may depend on upstream activation of the ras pathway were especially sensitive to the drug. To define the important targets of FTI action, the mechanism of cellular drug resistance was examined. It was not a function of altered drug accumulation or of FPTase insensitivity since, in all cell lines tested, FPTase activity was readily inhibited within 1 h of treatment with the inhibitor. Furthermore, the general pattern of inhibition of cellular protein farnesylation and the specific inhibition of lamin B processing were the same in sensitive and resistant cells. In addition, functional activation of Ras was inhibited to the same degree in sensitive and resistant cell lines. However, the FTI inhibited the epidermal growth factor-induced activation of mitogen-activated protein kinases in sensitive cells but not in two resistant cell lines. These data suggest that the drug does inhibit ras function and that resistance in some cells is associated with the presence of Ras-independent pathways for mitogen-activated protein kinase activation by tyrosine kinases. We conclude that FPTase inhibitors are potent antitumor agents with activity against many types of human cancer cell lines, including those with wild-type ras.

Cloning and expression of the cDNA of chicken cation-independent mannose-6-phosphate receptor

We cloned and sequenced the 8767-bp full-length cDNA for the chicken cation-independent mannose-6-phosphate receptor (CI-MPR), of interest because, unlike its mammalian homologs, it does not bind insulin-like growth factor II (IGF-II). The cDNA encodes a protein of 2470 aa that includes a putative signal sequence, an extracytoplasmic domain consisting of 15 homologous repeat sequences, a 23-residue transmembrane sequence, and a 161-residue cytoplasmic sequence. Overall, it shows 60% sequence identity with human and bovine CI-MPR homologs, and all but two of 122 cysteine residues are conserved. However, it shows much less homology in the N-terminal signal sequence, in repeat 11, which is proposed to contain the IGF-II-binding site in mammalian CI-MPR homologs, and in the 14-aa residue segment in the cytoplasmic sequence that has been proposed to mediate G-protein-coupled signal transduction in response to IGF-II binding by the human CI-MPR. Transient expression in COS-7 cells produced a functional CI-MPR which exhibited mannose-6-phosphate-inhibitable binding and mediated endocytosis of recombinant human beta-glucuronidase. Expression of the functional chicken CI-MPR in mice lacking the mammalian CI-MPR should clarify the controversy over the physiological role of the IGF-II-binding site in mammalian CI-MPR homologs.

Herbimycin A induces the 20 S proteasome- and ubiquitin-dependent degradation of receptor tyrosine kinases

Herbimycin A is an ansamycin antibiotic isolated as an agent that reverses morphological transformation induced by v-src. Although herbimycin A is widely used as a tool for inhibiting multiple tyrosine protein kinases and tyrosine kinase-activated signal transduction, its mechanism of action is not well defined and includes a decrease in both tyrosine kinase protein levels and activity (Uehara, Y., Murakami, Y., Sugimoto, Y., and Mizuno, S. (1989) Cancer Res. 49, 780-785). We now show that herbimycin A induces a profound decrease in the total cellular activity of transmembrane tyrosine kinase receptors, such as insulin-like growth factor, insulin, and epidermal growth factor receptors. A substantial proportion of the in vivo inhibition could be explained by an increase in the rate of degradation. The enhanced degradation of insulin-like growth factor-insulin receptor was prevented by inhibitors of the 20S proteasome, whereas neither lysosomotropic agents nor general serine- and cysteine-protease inhibitors were active in preventing receptor degradation induced by herbimycin A. Moreover, in a temperature-sensitive mutant cell line defective in the E1-catalyzed activation of ubiquitin, herbimycin A treatment at the restrictive temperature did not result in the degradation of insulin receptor. These results suggest that herbimycin A represents a novel class of drug that targets the degradation of tyrosine kinases by the 20S proteasome. The ubiquitin dependence of this process indicates that this degradation of tyrosine kinases might involve the 20S proteasome as the proteolytic core of the ubiquitin-dependent 26S protease.

Cardiac plasma membrane physical properties and beta-adrenergic receptor function are unaltered in portal-hypertensive rats

We have previously demonstrated that impairment of cardiac contractility in a rat model of cirrhosis may be secondary to altered cardiac plasma membrane physical properties affecting beta-adrenergic receptor function. It is unclear whether this is caused by the cirrhosis or by the portal hypertension in this model, so we studied cardiomyocyte plasma membrane physical properties, lipid composition, and beta-adrenergic receptor function in a rat model of prehepatic portal hypertension without cirrhosis. Portal hypertension was induced by graded portal vein stenosis, whereas controls had a sham operation. Cardiac sarcolemmal plasma membrane physical properties were studied by fluorescent polarization methods using diphenylhexatriene and a series of anthroyloxy-stearic acids to estimate, respectively, the static and dynamic components of membrane fluidity. beta-Adrenergic receptor density and binding affinity were measured using 3H-dihydroalprenolol as a radioligand. Isoproterenol-stimulated adenylyl cyclase activity was measured by radioimmunoassay. Neither the static nor the dynamic components of membrane fluidity were significantly different in portal-hypertensive rats compared with the controls. The membrane cholesterol, phospholipid content, and the cholesterol/phospholipid ratio did not differ between the two groups. beta-Adrenergic receptor density and binding affinity in the portal-hypertensive rats (respectively, 1.65 +/- 0.06 pmol/mg protein and 6.78 +/- 0.80 nmol/L) were not different from controls (1.76 +/- 0.17 pmol/mg protein and 7.25 +/- 1.48 nmol/L). Isoproterenol-stimulated adenylyl cyclase activity in membranes from portal-hypertensive rats did not significantly differ from controls. We conclude that cardiac plasma membrane physical properties and beta-adrenoceptor function in portal hypertensive rats remains unimpaired, suggesting that the cardiomyopathy of cirrhosis is not caused by portal hypertension per se.

[SIMA leakage into stroma and lymph node metastasis in cervical adenocarcinoma]

The relationship of small intestine mucin antigen (SIMA) leakage into stroma and tumor lymph node metastasis was studied by SIMA immunohistochemical stain in the cervical adenocarcinoma of uterus. The results showed that the more SIMA leakage into stroma, the more possibility of lymph node metastasis. There was no difference between the SIMA staining intensity in the primary tumor or metastatic tumor. Mucin leakage into stroma may play an important role in cervical adenocarcinoma metastasis.

[Lumbar spinal stenosis syndrome: classification, pathology and operative consideration]

A total of 168 cases of lumbar spinal stenosis syndrome were operated on in recent 6 years. They included 13 cases of developmental spinal stenosis and 155 cases of acquired spinal stenosis. All patients were followed up for an average of 2 years and 7 months, ranging from 3 months to 5 years and 10 months. The results of treatment were not satisfactory in developmental spinal stenosis (excellent 46.2%, good 30.7%, fair 15.4%, poor 7.7%), but good in acquired spinal stenosis (excellent 72.2%, good 22.6%, fair 5.2%, poor 0). Moreover, with different classification and pathology, acquired spinal stenosis had different results. The authors stressed that it is very important to consider the methods and the range of operation according to the pathological characteristics of myelography and CTM of lumbar spinal stenosis.

[The effects of antitumor agents of croton alkaloids and cisplatin on human red blood cell membranes]

The effects of antitumor drugs of croton alkaloids (CA) extracted from croton, and cisplatin on the structure of human erythrocyte membrane and bovine serum albumin (BSA) were studied with the techniques of circular dichroism, fluorescence spectroscopy and ultraviolet absorption. From measuring circular dichroism between 200-240nm, it was found that the alpha helix of membrane and BSA increased after CA addition. Cisplatin was also found effective in altering membrane alpha helical content. BSA showed a loss of fluorescence intensity and a blue-shift of emission peak after CA addition. The florescence quenching and peak shift may reflect the movement of tryptophan to a more nonpolar environment (the hydrophobic portions of proteins). This is consistent with the increase in helicity of BSA in the presence of CA. From measuring fluorescence polarization of membrane, it was found that membrane fluidity decreased in the presence of CA, but did not change in the presence of cisplatin. The results indicate that both CA and cisplatin lead to alterations in the secondary structure of membrane protein. The conformation change in membrane protein may account for the pharmocological effect of CA and cisplatin.

[Limb-salvage surgery in 60 patients with osteosarcoma]

Limb-salvage surgery plays an important role in the treatment of osteosarcoma. From 1974 to 1993, 104 patients with osteosarcoma were treated in our department. Sixty of them were treated with limb-salvage procedures. In fourty-four patients of stage II B receiving adjuvant chemotherapy, the five-year survival rate was 46.69%. The overall local recurrence rate was 15%. The infection rate was 12.9%, and mechanical complication occurred in 14.8% of the patients. The functional result was generally good. Improved concepts of en bloc resection and better reconstructive techniques suggest that limb-salvage procedures are not only possible but can provide excellent functional result in patients with osteosarcoma. Further work must be directed to reducing local recurrence and improving reconstructive techniques.

[Rectal administration of ash bark]

A TLC-densitometric method was applied to determine aesculin in rabbit blood. The best way for ash bark rectal administration was found by orthogonal design [L4(2(3))]. The two routes of administration (per rectal, P.O.) were compared by bioavailabilities and the result indicated that per rectal was better than P.O. Modified isolated rectum-bag method was applied successfully to finding the best way for rectal administration of ash bark.

[Research on rectal administration of bark of official Magnolia]

Fluorescence assay was applied to the determination of magnolol in rabbit blood, and the best way to administer the bark of official magnolia per rectal was established by orthogonal test. Then the two routes of administration were compared by AUC of magnolol and per rectal was found better than P.O. In addition, the modified isolated rectum-bag method was applied successfully to the research on rectal administration of bark of official magnolia.

[Bacteriostasis of rhizoma Coptidis combined with trimethoprim (TMPO)]

The agar-dilution method was adopted to study contrastively the bacteriostasis of Rhizoma Coptidis and TMP, and also of the two drugs in combination. The results indicate that the combination works in good cooperation against Escherichia coli, Bacillus pyocyaneus, Staphylococcus aureus, Shigella flexneri and S. dysenteriae.

Complex between bovine ribonuclease A and porcine ribonuclease inhibitor crystallizes in a similar unit cell as free ribonuclease inhibitor

We obtained three different morphologies of co-crystals of bovine ribonuclease A and porcine ribonuclease inhibitor. X-ray quality crystals were grown in 1.3M ammonium sulfate, 100 mM sodium acetate (pH 5.0) and 20 mM dithiothreitol at 21 degrees C. These crystals have the symmetry of the tetragonal space group I4 with a = 133.3 A and c = 86.7 A and diffract to 2.5 A resolution; they have the same symmetry and only slightly different cell parameters than the crystals of free ribonuclease inhibitor. Polyacrylamide gel electrophoresis and the crystal density indicate that both ribonuclease inhibitor and ribonuclease A are present in the crystals. Although small, crystals are suitable for three-dimensional structural analysis.

Permanence of populations in a polluted environment

Studies of several population-toxicant models are discussed. Under the hypothesis that the exogenous input of toxicant into the environment is periodic in time, the conditions for permanence of populations are obtained.

Education selectivity in internal migration in mainland China

"The purpose of this paper is to study the selectivity in...internal migration in Mainland China with respect to the level of education, based on a sample of young adults (aged 17-29) taken from the micro data of the 1987 one-percent National Population Survey (NPS87)....[We focus first] on the education selectivity in migrations among the city, town and rural strata of the urban/rural hierarchy [and then examine] the education selectivity in migration among metropolitan, coastal and interior regions." (SUMMARY IN CHI)

Membrane physical properties determine cardiac beta-adrenergic receptor function in cirrhotic rats

To elucidate the basic membrane mechanisms underlying cirrhotic cardiomyopathy, cardiac sarcolemmal plasma membrane physical properties, chemical composition, beta-adrenoceptor density, binding affinity, and isoproterenol-stimulated adenosine 3',5'-cyclic monophosphate (cAMP) production were studied. Cirrhosis was induced by chronic bile duct ligation, while controls underwent a sham operation. The cardiac plasma membrane of cirrhotic rats was found to be more rigid than controls, primarily due to an increased cholesterol-to-phospholipid ratio. In cirrhotic animals, beta-adrenergic dysfunction was evident with a 21% decrease in beta-adrenoceptor density but no alteration in binding affinity. Despite the modest decrease in receptor number, beta-adrenoceptor-stimulated cAMP production was decreased by 37% in cirrhotic rats. When the membrane physical properties of the cirrhotic rats were restored to normal, by incubation with the fluidizing agent 2-(2-methoxy-ethoxy)ethyl 8-(cis-2-n-octylcyclopropyl)octanoate (A2C), isoproterenol-stimulated cAMP production also increased to levels indistinguishable from control animals. Restoration of membrane physical properties had no effect on either beta-adrenoceptor density or binding affinity. These results suggest that the increased rigidity of cardiomyocyte plasma membranes seen with cirrhosis is associated with decreased beta-adrenoceptor function. Moreover, restoring normal physical properties may result in restoration of beta-adrenoceptor-mediated contractile function.

Studies on the relationship between sway disease of bactrian camels and copper status in Gansu province

The clinical signs of camel sway disease in the Hexi Corridor of Gansu province were defined. The contents of eight minerals in soils, in forage and in the blood and hair of bactrian camels from this region were determined. The related blood indices were also measured. The concentration of molybdenum in soils and forage was 4.8 +/- 0.02 and 4.8 +/- 0.25 micrograms/g (dry matter), respectively, the copper to molybdenum ratio in the forage being only 1.3. The concentration of copper in blood and hair from the camels was 0.28 +/- 0.17 micrograms/ml and 3.50 +/- 1.00 micrograms/g, respectively. There was a hypochromic microcytic anaemia and a low level of ceruloplasmin in the blood. It is therefore suggested that sway disease of bactrian camels in this region is caused by secondary copper deficiency, mainly due to the high molybdenum content in soils and forage. The copper deficiency in the camels was aggravated during reproduction. Oral administration of copper sulphate can prevent and cure the disease.

The thickness of shock layers in liquid chromatography

At high concentrations, one boundary (the front if the isotherm is convex upward) of the elution band of a single component becomes very steep. Similarly, in frontal analysis, the same boundary is self-sharpening. These steep boundaries are called shock layers. They result from the steady-state equilibrium between a nonlinear thermodynamics of phase equilibrium on the one hand, which tends to create a concentration discontinuity, and axial dispersion and a finite rate of mass transfer on the other hand, which tend to relax the concentration gradient. We show that the width of experimental breakthrough curves recorded in frontal analysis agrees well with the prediction of the shock layer theory of Rhee and Amundson in the high concentration range. It is a function of the coefficients of the column HETP equation and the height of the concentration step and is independent of the column length, after the steady state is achieved. In the low concentration range, a discrepancy is observed when the column length is short and the migration distance is insufficient to achieve constant pattern behavior.

Further studies on the plasma-sprayed amorphous phase in hydroxyapatite coatings and its deamorphization

Plasma-sprayed hydroxyapatite coatings contain a quite large amount of amorphous phase. Infrared analysis shows that the plasma-sprayed amorphous phase is an oxyapatite and the coating predetermined as a hydroxyapatite is proved to be an oxyhydroxyapatite with a small quantity of hydroxyapatite. Heat treatment promotes the transformation of amorphous oxyapatite into a crystalline hydroxyapatite structure and reduces the dissolution rate of the coatings. Further studies focus on the properties of the amorphous phase, showing that amorphous oxyapatite is more soluble in 0.15 M lactic acid at 25 degrees C and that water molecules can accelerate the amorphous/crystalline transformation of the hydroxyapatite structure during the plasma-spraying process.

Amorphous phase and morphological structure of hydroxyapatite plasma coatings

It is shown that under standard conditions of plasma spraying hydroxyapatite powder reaches the substrate in the form of molten drops. On striking the surface, the molten drop splatters, cools rapidly and solidifies. Consequently, a pancake particle surrounded by tiny spherical or differently shaped particles is formed on the substrate. The solidified particles are partly crystallized. Besides the crystalline hydroxyapatite, they contain some supercooled molten hydroxyapatite, i.e. amorphous hydroxyapatite. Build-up of these particles during coating gives a porous pancake-globular structure. During a brief vacuum heating at 630 degrees C, the amorphous phase is crystallized and completely crystalline hydroxyapatite coatings are obtained.

Field molecular epidemiology. Feasibility of monitoring for the malignant bladder cell phenotype in a benzidine-exposed occupational cohort

Modern molecular and cellular biology have provided powerful new approaches to study cancer in the research laboratory, but these techniques have not been used extensively in field studies or in screening of high-risk occupational cohorts. The primary objective of this study was to demonstrate the use of cellular and molecular methods in combination with medical and epidemiologic methods to identify cancer cases, risk factors, and markers in a previously identified and defined cohort of Chinese workers exposed to benzidine. The screening of exposed workers included occupational, medical, and smoking histories to identify exogenous risk factors, a limited physical examination, Papanicolaou (PAP) urinary cytology, measurement of urine pH, quantitative fluorescence image analysis (QFIA) cytology to detect DNA hyperploidy, and quantitative fluorescence to detect expression of a low-grade bladder tumor-associated antigen (p300) by exfoliated urothelial cells and elevated expression of the neu oncogene product (p185). Detailed analysis of the accuracy of epidemiologic data and the adequacy of samples and accuracy of molecular techniques was carried out. Three groups were included in this study: group 1 included 23 bladder cancer cases who had previously been exposed to benzidine and served as two surrogates for late-emerging disease; group 2 consisted of 20 subjects with previous exposure history but not previously diagnosed with bladder cancer; and group 0 was the nonexposure and nonbladder cancer controls. The results showed that accurate questionnaire data and urine samples can be obtained at remote sites. Among the 20 group 2 subjects, two displayed abnormal findings by both QFIA cytology and p300 expression and were later confirmed to have bladder cancer.(ABSTRACT TRUNCATED AT 250 WORDS)

The AMP-binding domain on adenylate kinase. Evidence for a conformational change during binary-to-ternary complex formation via photoaffinity labeling analyses

The topological location of the nucleotide substrate binding environments on adenylate kinase has been explored with the fluorescent molecule [4-benzoyl]benzoyl-1-amidofluorescein (BzAF) and the nucleotide analog 3'-O-[4-benzoyl]benzoyl-ATP (BzATP), which are site-directed photoaffinity probes that bind covalently at the individual nucleotide sites. The MgBzATP substituted for MgATP as a substrate for this enzyme, whereas BzAF, which is neither a substrate nor a nucleotide, behaved as a competitive inhibitor for each nucleotide site independently. BzAF could be directed specifically to either of the nucleotide sites by near saturation of the second site with its natural nucleotide substrate. Using this second site blocking approach, each nucleotide site, in turn, could be protected competitively from BzAF-induced photoinhibition by the presence of its natural substrate. This strategy showed that under photolysis, the Kd(BzAF) of 0.1 mM (for the MgATP site) and 0.2 mM (for the AMP site) were nearly identical with the Km(app) values determined for MgATP and AMP, respectively. Pseudo first-order photolysis kinetics with [3H]BzAF revealed covalent binding stoichiometries for full inhibition of 1 mol of probe/mol of enzyme at either site. Thus, we prepared the binary complex ([3H]BzAF-enzyme) by photo-labeling the MgATP site-blocked enzyme with [3H]BzAf to 1:1 molar stoichiometry. Tryptic digestion followed by partial sequencing of the [3H]BzAF-labeled enzyme disclosed that BzAF was bound specifically within the peptide span Gly64-->Arg77. This amino acid domain therefore probably constitutes the neighborhood identifiable with AMP binding. Furthermore, we also achieved double photocovalent labeling of adenylate kinase with both photoprobes, by first cross-linking with approximately 1 mol of MgBzATP, followed by approximately 0.9 mol of [3H]BzAF, thus generating a ternary covalent complex. Comparison of the fluorescence of the binary species and the ternary (BzATP-enzyme-[3H]BzAF) complex revealed altered fluorescence emission profiles, which could indicate that a conformational change occurs during formation of the ternary (or transition state) complex.

Divalent cation-dependent stimulation of ligand binding to the 46-kDa mannose 6-phosphate receptor correlates with divalent cation-dependent tetramerization

The quaternary structure and binding activity of the murine 46-kDa mannose 6-phosphate receptor (46MPR) were studied in semi-intact murine cells that overexpress the murine receptor. Chemical cross-linking studies showed that the murine 46MPR exists in monomer, dimer, and tetramer forms in membranes of overexpressing murine cells. Treatment of permeabilized cells with Mn2+ increased the tetramer form of 46MPR, and this tetramerization was reversed by removal of Mn2+. Thus, the divalent cations affected the distribution of receptor among the three forms, favoring tetramerization at the expense of dimer and monomer. Low temperature (4 degrees C) also increases the fraction present as tetramer. The binding assay results show that Mn2+ is required for the 46MPR to achieve and retain the ability to bind ligand at 37 degrees C but not at 4 degrees C. Preincubation with Mn2+ produced a 3-fold increase in Man-6-P-specific binding of beta-glucuronidase which paralleled the 3-fold increase in tetramer seen during preincubation with Mn2+. The similarity of the effects of addition and removal of Mn2+ on enzyme binding to the effects of Mn2+ on favoring tetramer formation suggests that divalent cation-dependent tetramerization of the 46MPR contributes to the stimulation of ligand binding to the 46MPR by divalent cations.

Experimental study of high-frequency two-way jet ventilation

BACKGROUND AND METHODS

A new mode of jet ventilation, high-frequency two-way jet ventilation, was devised and introduced to increase CO2 elimination. High-frequency two-way jet ventilation was achieved by adding reverse jet pulses inside the trachea through an intratracheal reverse jet system to the expiratory phase of common high-frequency jet ventilation. The ventilatory efficiency and features of high-frequency two-way jet ventilation were investigated and compared with those features of high-frequency jet ventilation in ten dogs in the same experimental condition. Random sample selection and randomized crossover trial were used for comparison between high-frequency two-way jet ventilation and high-frequency jet ventilation. Peak inspiratory pressure, end-expiratory pressure, and the arterial blood gas variables (PaO2, PaCO2, and pH) were measured during the study.

RESULTS

PaCO2 with high-frequency two-way jet ventilation was about 35% lower than that with high-frequency jet ventilation (from 45 to 29 torr [6.0 to 3.9 kPa], p less than .01). Simultaneously, peak inspiratory pressure and end-expiratory pressure during high-frequency two-way jet ventilation were significantly lower than those same variables measured during high-frequency jet ventilation. End-expiratory pressure of high-frequency two-way jet ventilation was a negative pressure (-2.45 +/- 0.45 cm H2O). The pH of high-frequency two-way jet ventilation was significantly higher than that of high-frequency jet ventilation.

CONCLUSIONS

Compared with high-frequency jet ventilation, high-frequency two-way jet ventilation demonstrated a ventilatory feature of increasing CO2 elimination and simultaneously decreasing airway pressure.

Personal characteristics of Chinese children and their discrepancies: a report on children's development in Anhui (I)

The authors report on a 1990 survey on the characteristics of children in China which included 1,000 primary school pupils in Anhui Province. The focus is on differences between only children and those with brothers or sisters. The results suggest that "the development of temperaments, moral character, behavior and basic ability of primary school pupils in Anhui is generally healthy despite certain discrepancies among different types of children."

The threshold of survival for system of two species in a polluted environment

The effects of toxicants on naturally stable two-species communities are studied. Persistence-extinction thresholds are given for populations in the toxicant stressed Lotka-Volterra model of two interacting species. The threshold results are expressed in terms of relationships involving the population intrinsic growth rates, dose-response parameters, and interaction rates.

[Observation on the epidemiologic efficacy for 9 years on epidemic meningococcal polysaccharide vaccine of group A by district immunization method]

According to previous studies, there might be a peak of epidemic meningitis in Baoding City in 1984. For preventing the epidemic, we carried out vaccination with meningococcal polysaccharide vaccine by district immunization method during the 1980-1984 and then vaccination only to the children aged 12-24 months every year. The vaccination rate was 80.01% in 1980-1984 and was 97.15% in 1985-1988. During the 9 years, 833,377 children of vaccination group were observed, 4 of whom developed this disease, with an incidence of 0.48/100,000; and 304,085 children in the control group were observed, 25 of whom contracted this illness, with an incidence of 8.22/100,000. The protective rate of vaccine was 94.16% and the efficacy index was 1:17.12. This result showed that peak year of epidemic meningitis predicted in 1984 was prevented by vaccine immunization and the incidence of this disease was continuously kept less than 1/100,000 for 9 years.

A Chinese female postnuptial leaving home model--a procedure for analyzing main parameters alpha and beta in the setting up, testing and estimation of the model

"The first section of this article...sets up a model for leaving home after marriage that is suited to China's situation. The second section performs a statistical test and verification of the formulated model for leaving home after marriage. The third section...proposes a method for analyzing the main parameters...in the model...." The model is set up along the lines of the Brass-Gompertz relational fertility model.