[Application of adaptive resonance theory network to the quality evaluation of radix Sophorae flavescentis]

ART1 and ART2 models of adaptive resonance theory network have been employed in quality evaluation of 40 Radix Sophorae Flavescentis samples collected from different regions of China. Based on the UV data of MeOH extract and IR data of CHCL3 extract, Shannon information theory has been used for feature selection. The results consist with those of traditional appraisal.

CHEB, a convulsant barbiturate, evokes calcium-dependent spontaneous glutamate release from rat cerebrocortical synaptosomes

CHEB [5-(2-cyclohexylidene-ethyl)-5-ethyl barbituric acid] is a potent convulsant barbiturate that causes direct neuronal excitation by an unknown mechanism. We have analyzed the effects of CHEB on the release of endogenous glutamate from rat cerebrocortical synaptosomes using an on-line enzyme-coupled fluorimetric assay. CHEB evoked spontaneous Ca(2+)-dependent glutamate release with an EC50 = 14.2 microM and an Emax = 3.2 mumol/min/mg. The non-convulsant barbiturates pentobarbital and phenobarbital evoked significantly less glutamate release at high concentrations. CHEB (30 microM) increased intrasynaptosomal [Ca2+] by 58 +/- 4 nM (p < 0.01; n = 4) above baseline compared to an increase of 5 +/- 4 nM (NS; n = 4) produced by pentobarbital (30 microM). CHEB-evoked glutamate release was inhibited by pentobarbital, phenobarbital, EGTA, CoCl2/CdCl2 and flunarizine, but not by local anesthetics, tetrodotoxin, nitrendipine or omega-conotoxin GVIA. These results demonstrate that CHEB acts as a potent and effective secretogogue for glutamate by a pre-synaptic mechanism that does not require activation of Na+ channels or of L-type or N-type Ca2+ channels. Stimulation of spontaneous glutamate release may contribute to the convulsant properties of CHEB.

[Preparation and identification of monoclonal antibody GB2 directed against human breast cancer serum antigen]

Spleen cells from BALB/c mice immunized with human breast cancer serum antigen were fused with murine myeloma SP 2/0 cells. After screening with ELISA and limited-dilution cloning, one hybridoma which could stably secrete specific antibody was obtained and designated McAbGB2. The titer of McAbGB2 was up to 1.2 x 10(6) after purified by ammonium sulfate and DEAE-cellulose. The McAbGB2 was defined as murine IgG1 by agarose double immunodiffusiong. Immunoblotting analysis revealed that the antigens with molecular weights of 116 kd and 45 kd recognized by McAbGB2 were distributed in human breast cancer tissue and serum.

[Radix Sophorae flavescentis quality by chemical pattern recognition]

The PCA method and NLM technology were used to study on quality of 40 Radix Sophorae Flavescentis samples collected from different regions of China. The results showed were unanimous with that of traditional appraisal.

[Flavone constituents in the seeds of Sophora vicii folia Hance]

Four flavone compounds have been separated from the mature seeds of Sophora vicii folia. By means of physico-chemical and spectroscopic analysis, their structures have been identified as 5,7,3'-trihydroxy-4'-methoxyflavone (I); 7,3'-dihydroxy-1'-methoxyflavone (II); 7,4'-dihydroxyflavone (III) and 7,3',4'-trihydroxyflavone (IV). All of them are found in S. viciifolia for the first time, and I and II are found Sophora genus for the first time.

Formulation and antitumor activity evaluation of nanocrystalline suspensions of poorly soluble anticancer drugs

PURPOSE

Determine if wet milling technology could be used to formulate water insoluble antitumor agents as stabilized nanocrystalline drug suspensions that retain biological effectiveness following intravenous injection.

METHODS

The versatility of the approach is demonstrated by evaluation of four poorly water soluble chemotherapeutic agents that exhibit diverse chemistries and mechanisms of action. The compounds selected were: piposulfan (alkylating agent), etoposide (topoisomerase II inhibitor), camptothecin (topoisomerase I inhibitor) and paclitaxel (antimitotic agent). The agents were wet milled as a 2% w/v solids suspension containing 1% w/v surfactant stabilizer using a low energy ball mill. The size, physical stability and efficacy of the nanocrystalline suspensions were evaluated.

RESULTS

The data show the feasibility of formulating poorly water soluble anticancer agents as physically stable aqueous nanocrystalline suspensions. The suspensions are physically stable and efficacious following intravenous injection.

CONCLUSIONS

Wet milling technology is a feasible approach for formulating poorly water soluble chemotherapeutic agents that may offer a number of advantages over a more classical approach.

A p65/p95 neural surface receptor is expressed at the S-G2 phase of the cell cycle and defines distinct populations

A surface receptor complex of Mr approximately 65 000 (p65) and approximately 95 000 (p95) is expressed in cells of the central nervous system of mice. This receptor is recognized by monoclonal antibody 87.92.6 or by reovirus type 3 haemagglutinin as unnatural ligands. The p65/p95 receptor is expressed mostly in neural embryonic precursors undergoing proliferation, especially those in the S-G2 phase of the cell cycle. Receptor expression decreases progressively throughout embryogenesis to low but detectable levels in the adult brain. Biochemical characterization revealed that the neural p65/p95 receptor complex is indistinguishable from the p65/p95 receptor expressed in T cells, where receptor ligation leads to a mitogenic block. In neural and lymphoid tissues the p65/p95 receptor (or an associated protein) possesses a tyrosine kinase enzymatic activity. Receptor ligation in neural cells resulted in the rapid tyrosine phosphorylation of cellular proteins which are different from substrates phosphorylated in T cells. Differential substrate coupling to the receptor may account for differences in signal transduction and biology between neural cells and T cells. Further study of this receptor complex may help define important features of neural proliferation, differentiation and survival.

Cerebrovascular amyloidosis in squirrel monkeys and rhesus monkeys: apolipoprotein E genotype

Some neuropathological changes characteristic of aging and Alzheimer's disease (AD) in humans are present also in senescent non-human primates. The human apoE4 allele is associated with an increased risk of developing late-onset familial and sporadic AD. We found that rhesus monkeys and three subspecies of squirrel monkeys are homozygous for apoE phenotype with arginine at positions 112 and 158 as in human apoE4. However, in both species threonine replaces arginine at position 61 of human apoE. It was previously shown that arginine 61 was critical in determining apoE4 lipoprotein distribution in humans.

The application of NMR imaging to the studies of enhanced oil recovery in China

The advantages of the application of NMR imaging to the studies of enhanced oil recovery methods that include polymer slug flooding, combination slug flooding, and thermal soaking are described.

[Detection of serum isoferritin level in 195 patients with cancer]

ELISA (double-determinant) was used to detect the serum isoferritin (SIF) levels in 42 patients with nasopharynx cancer (NPC), 38 with lung cancer (LC), 26 with esophageal cancer (EC) and 89 with other cancers, a total of 195 cases (151 males and 44 females). The results revealed that the positive rate of SIF in patients with cancer was 73.8% (144/195), among which, the positive rates in patients of stage I-II, stage III-IV, in patients not operated upon and in those after operation were 64.8%, 81.3%, 81.4% and 63.4%, respectively. Statistics was significantly different in SIF level between the stage I-II and III-IV groups, and between the un-operation and after operation groups (P < 0.001) by rank sum testing. The positive rates of NPC, LC and EC were 73.8%, 86.8% and 73.1%, respectively. The results have demonstrated that isoferritin is a malignant neoplasm associated antigen, and SIF level is related closely with the development of the tumor and operative treatment.

Lung cancer mortality update and prevalence of smoking among copper miners and smelters

OBJECTIVES

The aim of this investigation was to study the cancer mortality of Chinese copper miners and smelters further, with particular reference to that from lung cancer, and smoking prevalence.

METHODS

From an earlier follow-up (1970-1985) of the mortality of the two cohorts, all new death cases registered since 1985 were recorded, and the mortality analysis was extended through 1992. A questionnaire survey of smoking habits was carried out in three samples, randomly chosen from the copper miners (N = 1125), smelters (N = 603), and local residents (N = 1517) of Tongling city.

RESULTS

Lung cancer was significantly increased among the copper miners [standardized mortality ratio (SMR) 152, 95% confidence interval (95% CI) 123-187], but not among the copper smelters (SMR 102, 95% CI 53-178). Smoking was more prevalent among copper miners than among local male residents (71.7 versus 64.3%, P < 0.001), whereas among the smelters it was significantly less prevalent (57.4 versus 64.3%, P < 0.005). Similar patterns were found for the average number of cigarettes smoked daily among the miners (21.6 +/- 7.2), smelters (15 +/- 7.1), and local male residents (19.2 +/- 7.3).

CONCLUSIONS

In addition to occupational exposures, cigarette smoking may partly play a role in influencing mortality from lung cancer among Chinese copper miners and smelters.

[Time selection of cesarean section in preeclampsia]

OBJECTIVE

To study the relationship between the time of cesarean section and the outcome of mothers and newborns.

METHODS

One hundred and three pregnant women suffered from preeclampsia (< 37 weeks 34, > or = 37 weeks 69) and 109 newborns (twins 6) were enrolled for study. The rates of neonatal asphyxia, perinatal mortality and morbidity such as pneumonia, respiratory distress syndrome (RDS) and meconium staining amniotic fluid were observed.

RESULTS

The cesarean section rate was 83.06% in preeclampsia cases and it was 94.44% in cases with gestational age less than 37 weeks. There was no maternal death. Neonatal asphyxia rate was 6.67%, and the perinatal mortality rate was 6.67%. After 37 weeks the perinatal mortality rate was 1.41% (P > 0.05) and neonatal asphyxia rate 28.17% (P < 0.01). The rate of pneumonia and meconium staining amniotic fluid were obviously increased.

CONCLUSIONS

These observations suggest that fetal lung maturation tended to ahead of gestational age in pregnancy induced hypertension. After 37 weeks complications of both mother and baby increased. In severe preeclampsia cases, pregnancy should be terminated at 34-36 gestational weeks, and cesarean section is the first choice.

[Determination of di-alpha-phosphatidylcholine in the seeds of Astragalus chinensis L. by TLC-scanning]

PC (di-alpha-phosphatidylcholine) contents in the seeds of Astragalus chinensis were determined by TLC-scanning. These data can be used to study the phospholipids in Astragalus chinensis and evaluate its quality. This method is simple, sensitive and has better reproducibility, higher recoveries and steadiness in operation.

7,12-dimethylbenz[a]anthracene induces oxidative DNA modification in vivo

Initiation and promotion are major stages in the multistage carcinogenesis process. Formation of initiating carcinogen-DNA base adducts leads to heritable genetic changes, but the tumor-promoting events induced by complete carcinogens have not, as yet, been elucidated. Oxidant production and oxidative DNA damage induced by phorbol esters (i.e., 12-O-tetradecanoyl-phorbol-13-acetate) are associated with tumor promotion, while antioxidants and inhibitors of oxidative DNA damage suppress promotion and carcinogenesis. Our goal was to establish whether a carcinogen that requires oxidative metabolism for its activity can also induce oxidant production and DNA base oxidation. We found that topical treatment of SENCAR mice with 7,12-dimethylbenz[a]anthracene, which induces tumors in 40-50% of the mice, also causes hydrogen peroxide production and formation of oxidized bases (i.e., 8-hydroxyl-2'-deoxyguanosine and 5-hydroxymethyl-2'-deoxyuridine) in epidermal DNA. The levels of oxidized bases were of comparable magnitude to those mediated by the potent tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate. The oxidized bases persisted over several weeks in epidermal DNA. These oxidative events appear to be temporally associated with inflammatory responses that include edema and polymorphonuclear leukocyte infiltration, which remained elevated over longer periods of time and at higher levels than those induced by phorbol ester. Because these processes are usually associated with tumor promotion, our results support the conjecture that oxidative events may be involved in what is operationally referred to as the tumor promotion process by 7,12-dimethylbenz[a]anthracene.

Ministrokes in rat barrel cortex

BACKGROUND AND PURPOSE

Many stroke models in rats are based on occlusion of the middle cerebral artery, which supplies a significant portion of multifunctional cortical and deep structures in the cerebral hemisphere. The purpose of this study was to develop a model for direct observation in real time of blood flow in and around focal ischemic regions of the cortex of known function.

METHODS

Cranial windows were placed over the parietal cortex of adult Wistar and Sprague-Dawley rats anesthetized with ketamine and xylazine. Whisker barrel cortex responding to stimulation of the contralateral whiskers was identified by an intrinsic optical signal. Transits of vital dyes were recorded by videomicroscopy before and after ligation of three to six branches and major collaterals of the middle cerebral artery through the dura. Infarcts were demonstrated with triphenyl-tetrazolium chloride staining; their relation to barrel cortex was determined by Nissl and cytochrome oxidase histology.

RESULTS

Reduced blood flow in small ischemic regions was outlined by patient blue violet in the surrounding nonischemic area; arteriovenous latencies increased more than four times in ischemic cortex. Infarcts,typically 3 mm or less, were seen at 24 hours in 8 of 16 Wistar and 9 of 9 Sprague-Dawley rats. The ministrokes were confirmed by histology to be in the somatosensory cortex.

CONCLUSIONS

This model of local ischemia, produced deliberately in the functionally defined barrel cortex in rats, leads to ministrokes. Changes can be followed by videomicroscopy as they develop, and processes of recovery can potentially be monitored. Infarcts are confirmed by histology for their location and extent in the somatic representation.

[Mutagenicity and anti-mutagenicity assay of airborne suspended particles in Shijiazhuang city]

Samples of airborne suspended particles collected from five air monitoring sites in Shijiazhuang City in 1993 were analyzed with rapid synchronous mutagenicity and anti-mutagenicity tests. It revealed airborne suspended particles collected had direct and indirect mutagenicity, but no anti-mutagenicity, and there was seasonal difference in their mutagenicity, which showed a decreasing trend with an order of winter, spring, summer and autumn. Mutagenicity related positively to air concentrations of total suspended particles and sulfur dioxide, inversely to those of ozone, and did not related to those of nitrogen oxide and carbon monoxide.

Nicotine raises the influx of permeable solutes across the rat blood-brain barrier with little or no capillary recruitment

Nicotine (1.75 mg/kg s.c.) was administered to rats to raise local CBF (lCBF) in various parts of the brain, test the capillary recruitment hypothesis, and determine the effects of this increase in lCBF on local solute uptake by brain. lCBF as well as the local influx rate constants (K1) and permeability-surface area (PS) products of [14C]antipyrine and [14C]-3-O-methyl-D-glucose (3OMG) were estimated by quantitative autoradiography in 44 brain areas. For this testing, the finding of significantly increased PS products supports the capillary recruitment hypothesis. In 17 of 44 areas, nicotine treatment increased lCBF by 30-150%, K1 of antipyrine by 7-40%, K1 of 3OMG by 5-27%, PS product of antipyrine by 0.20% (mean 7%), and PS product of 3OMG by 0-23% (mean 8%). Nicotine had no effect on blood flow or influx in the remaining 27 areas. The increases in lCBF and K1 of antipyrine were significant, whereas those in K1 of 3OMG and in PS for both antipyrine and 3OMG were not statistically significant. The lack of significant changes in PS products implies that in brain areas where nicotine increased blood flow: (a) essentially no additional capillaries were recruited and (b) blood flow within brain capillary beds rises by elevating linear velocity. The K1 results indicate that the flow increase generated by nicotine will greatly raise the influx and washout rates of highly permeable materials, modestly elevate those of moderately permeable substances, and negligibly change those of solutes with extraction fractions of < 0.2, thereby preserving the barrier function of the blood-brain barrier.

[Chemical constituents of Astragalus chinensis L]

Three compounds have been isolated from the seeds of Astragalus chinensis. Their structures were identified on the basis of spectral data (UV, 13CNMR, 1HNMR, IR and MS) as octacosane, daucosterol and kaempferol.

Effects of okadaic acid and vanadate on TPA-induced monocytic differentiation in human promyelocytic leukemia cell line HL-60

Treatment of HL-60 cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) (1-5 nM) induced inhibition of cell growth and the appearance of an adherent monocyte-like cell type in a dose- and time-dependent manner. The extent of TPA-induced monocytic differentiation was found to be markedly reduced by okadaic acid (OA) (35 nM). OA had to be present for the early 12 h during treatment with TPA to reduce the induction of monocytic differentiation. The majority of cells (80%) were non-adherent but morphologically resembled mature myelocytes or granulocytes after treatment with TPA (5 nM) in the presence of OA (35 nM). Vanadate (VD), on the other hand, enhanced the extent of monocytic differentiation induced by low-dose of TPA (1 nM). These results indicated that dephosphorylation by tyrosine protein phosphatase and serine-threonine protein phosphatase may play an important role in the induction of monocytic and granulocytic differentiation.

Expression, characterization, and crystallization of the catalytic core of the human insulin receptor protein-tyrosine kinase domain

The deduced primary sequence of the cytoplasmic protein-tyrosine kinase domain of the insulin receptor contains a conserved kinase homology region (receptor residues 1002-1257) flanked by a juxtamembrane region and a C-terminal tail. A soluble 48-kDa derivative (residues 959-1355) containing these regions but lacking the first six residues of the juxtamembrane region had earlier been synthesized in Sf9 cells using a baculovirus expression system. The catalytic core of the kinase domain was studied first by proteolytic analysis of the 48-kDa kinase and then by expressing a series of truncated kinase domains in transiently transfected COS cells. Based on these studies, two core kinases of 34 (residues 985-1283) and 35 (residues 978-1283) kDa, respectively, were overexpressed in Sf9 cells. Biochemical characterization of the 35-kDa kinase revealed that the core kinase conserved the major functional properties of the native receptor kinase domain. Activity of the 35-kDa kinase toward a synthetic peptide increased more than 200-fold upon autophosphorylation, which occurred exclusively at Tyr-1158, Tyr-1162, and Tyr-1163; the largest increase was observed between bis- and trisphosphorylation of the kinase. The activated 35- and 48-kDa kinases were similar with respect to specific activity and ATP and Mg2+ requirements for peptide phosphorylation. Moreover, autophosphorylation appeared to initiate predominantly at Tyr-1162, immediately followed by phosphorylation at Tyr-1158 and then at Tyr-1163. The rate of autophosphorylation was dependent on enzyme concentration, consistent with a trans-phosphorylation mechanism. Finally, the 35-kDa kinase was crystallized, making possible elucidation of its three-dimensional structure by x-ray crystallography.

Phenotypic features of breast cancer cells overexpressing ornithine-decarboxylase

Polyamines (PA) have been shown to be critical mediators of estradiol-induced breast cancer cell proliferation. This finding suggests that constitutive activation of the PA pathway may promote tumor progression, possibly leading to hormone independence. To test this hypothesis, we transfected hormone-responsive MCF-7 breast cancer cells with a complementary DNA coding for ornithine-decarboxylase (ODC), the first rate-limiting enzyme in PA biosynthesis. Marked ODC overexpression observed in stably transfected clones was associated with a selective increase in cellular putrescine content, while spermidine and spermine levels were not altered. ODC-overexpressing MCF-7 cells were resistant to the antiproliferative effects of low but not high concentrations of the enzyme inhibitor, alpha-difluoromethylornithine. In agreement with our hypothesis, sensitivity to the growth-promoting action of estradiol was reduced by approximately one third (P < 0.001) in ODC-overexpressing MCF-7 cells compared with vector-only transfected clones. Basal growth under anchorage-dependent conditions was only marginally increased by ODC overexpression (P = 0.048), while clonogenicity in soft agar was actually reduced. These data suggest that activation of PA biosynthesis may contribute in part to the acquisition of estrogen independence by breast cancer cells. Since only putrescine content was increased as a result of ODC overexpression, these data may underestimate the overall influence of the PA pathway on breast cancer phenotype.

Polyamine profiles and growth properties of ornithine decarboxylase overexpressing MCF-7 breast cancer cells in culture

To determine the direct influence of the polyamine (PA) pathway on breast cancer phenotype, we employed a transfection approach to induce overexpression of the PA biosynthetic enzyme ornithine decarboxylase (ODC) in the hormone-responsive MCF-7 breast cancer cell line. Using a modified calcium phosphate method and an ODC cDNA coding for a truncated and more stable enzyme, we were able to achieve a moderate to marked degree of ODC overexpression (up to 150-fold) in a transient transfection system. ODC-overexpressing MCF-7 cells exhibited a selective increase in cellular putrescine content, while the levels of spermidine and spermine remained unaffected. Under defined culture conditions, overexpression of ODC resulted in a consistent but modest increase in [3H]thymidine incorporation into DNA which was similar in the presence and absence of 17-beta-estradiol, TGF-alpha, and IGF-I. In the presence of serum, the effect of ODC overexpression on basal [3H]-thymidine incorporation into DNA was inconsistent, possibly as a result of subtle differences in culture conditions. Overall, our results support the hypothesis that activation of the PA biosynthetic pathway may confer a growth advantage to breast cancer cells.

Small peptide mimics of nerve growth factor bind TrkA receptors and affect biological responses

Small monomeric cyclic analogs that mimic the beta-turn regions of nerve growth factor (NGF) were designed and synthesized. Potent competitive antagonists were derived from the NGF beta-turn C-D, which inhibited [125I] NGF binding to TrkA receptors and specifically inhibited optimal NGF-mediated neurite outgrowth in PC12 cells. The cyclic beta-turn A'-A" analog also inhibited NGF binding to TrkA receptors but with lower potency. These data indicate that beta-turns C-D and A'-A" are critical for TrkA binding and may confer neurotrophin receptor specificity. Furthermore, structural requirements for binding are absolute, because unconstrained analogs derived from the same regions had no effect. Compounds that mimic NGF will be useful in deciphering the interactions of NGF and its receptors and in rational drug design.

[Alkaloid constituents in the seeds of Sophora viciifolia Hance]

Six alkaloids were isolated from the mature seeds of Sophora viciifolia for the first time. On the basis of physicochemical and spectroscopic analysis, their structures have been identified as oxymatrine, oxysophocarpine, matrine, sophocarpine, sophoramine and sophoridine.

[Fecundify after treatment of tubal pregnancy]

This study is a follow-up analysis of 103 patients who desired to preserve their fertile ability after treatment of tubal pregnancy. Among the 103 cases, 58 were treated by unilateral salpingectomy, 15 by salpingostomy and 30 by drug conservative therapy.

RESULTS

67 cases had intrauterine pregnancy and 9 cases repeated ectopic pregnancy. The intrauterine pregnancy rate of the surgical group (71.2%) was higher than that of the nonsurgical group (50.0%). And the pregnancy rate of salpingostomy group (86.7%) was higher than that of salpingectomy group (67.2%). No repeated ectopic pregnancy occurred in the salpingostomy group. After three months of treatment, 45 cases were randomly sampled for tubal patency test. Bilateral tubal patency rate in salpingostomy group was 93.3% and in drug treatment group was 20.0%. These results indicated that tubal patency is an essential factor for normal pregnancy. Prevention of post-operative adhesion and treatment of pelvic inflammatory disease are important for increasing intrauterine pregnancy rate and decreasing repeated ectopic pregnancy rate.

Optimizing ACTH-stimulated steroid secretion by cultured adrenocortical tumor cells

If 1 mM supplemental Ca++, or 1.6 mg hemoglobin (Hb)/ml medium (23.5 uM, a concentration comparable to that in 1 ml mouse blood), was added to Eagle's minimum essential medium (MEM) (which contains 1 mM Ca++), basal and maximally stimulated 20-dihydroprogesterone (20-DHP) secretion by cultured Y-1 mouse adrenal tumor cells [49-65th passages] could be measured by radioimmunoassay after a 0.5 hr incubation. ACTH-stimulated, but not basal, 20-DHP secretion increased after 1 mM Ca++ treatment. 5 mM EGTA significantly reduced basal and stimulated 20-DHP secretion, although significant ACTH stimulation still remained. Basal and stimulated secretion significantly increased when Hb was present. Although O2 involvement in the Hb effect was tested by bubbling medium with 100% O2 for 10 minutes, basal and stimulated secretion was unaffected. Since proteins, such as Hb, non-specifically bind free steroids, enhancing secretion, albumin (Al) was compared to Hb. Al enhanced unstimulated, but not ACTH-stimulated, 20-DHP secretion. The Hb effect may not be due to non-specific protein-steroid binding. Ca++ supplementation and chelation studies suggest the necessity to optimize co-factors in steroidogenic tissue incubation media to maximize basal and stimulated steroid synthesis and secretion. Since physiologically relevant Hb levels enhanced basal and stimulated Y-1 cell steroid secretion by mechanisms other than protein-steroid binding and soluble O2 had little effect, Hb may more efficiently transport O2 to cultured cells than soluble O2 diffusion through medium does.

Crystal structure of the tyrosine kinase domain of the human insulin receptor

The X-ray crystal structure of the tyrosine kinase domain of the human insulin receptor has been determined by multiwavelength anomalous diffraction phasing and refined to 2.1 A resolution. The structure reveals the determinants of substrate preference for tyrosine rather than serine or threonine and a novel autoinhibition mechanism whereby one of the tyrosines that is autophosphorylated in response to insulin, Tyr 1,162, is bound in the active site.

Structural determinants of substrate selection by the human insulin-receptor protein-tyrosine kinase

Using NMR spectroscopy to visualise tyrosine phosphorylation kinetics in real time, we have investigated the sequence-dependent determinants of the selectivity of the human insulin receptor protein-tyrosine kinase for different tyrosine residues. The peptides used encompass the multiple-tyrosine-containing autophosphorylation site sequences from the insulin receptor kinase core domain (Tyr1158, Tyr1162 and Tyr1163) and from its specific C-terminal tail domain (Tyr1328 and Tyr1334). Comparison of the phosphorylation kinetics with those found for the tyrosine residues on a peptide comprising the regulatory tyrosine phosphorylation site of cdc2 points to the role of the primary sequence context of the phosphate acceptor. The particularly deleterious influence of a basic residue immediately C-terminal to the tyrosine is discussed in relation to the autophosphorylation properties of the regulatory loop regions of the insulin and epidermal growth factor receptor kinases. The data further suggest that receptor tyrosine kinase active sites and their substrate targets act in concert to ensure that specific downstream effects are activated.

[A comparison of the measurements of local cerebral blood flow by hydrogen clearance with hydrogen inhalation and by its electrochemical generation in brain tissue]

The goal of the present investigation was to compare data received by modifications of H2-clearance method with inhalation (H2-Inh) and electrochemical generation in brain tissue (H2-Gen) of H2 from the same recording electrodes in acute experiments (urethane 1g/kgip) with Wistar rats (n = 39). Block of three or four Pt electrochemically sharpened electrodes to tip diameters of 20-40 mu, 0.3-0.5 mm apart and 0.8-1.0 mm in length were inserted through the dura into sensorimotor cortex. One electrode was used for H2 generation (DC current 3-5 microA) and the others for PH2 recordings by polarographical method. Durations of H2 inhalation and H2 electrochemical generation were 3 or 10s with similar amplitudes of PH2. Data was recorded with a MacLab analog-digital system and Macintosh 11si computer. Recordings of resting LCBF were made with H2-Gen and H2-Inh the beginning of the experiment and after 40-60 min. LCBF was stimulated with inhalation of 7.5% CO2 for 60s. In 6 preparations LCBF was measured 10-20 min. after occlusions of two branches of the middle cerebral artery. After experiments the brain was perfused with India ink and cut in frozen sections for morphological analyses. The mean values of resting LCBF measured by H2-Inh was 1.67 +/- 0.54 ml/g/min. (+/- SD, N = 149), and by H2-Gen 3.17 +/- 0.91 (N = 147). The diffusional component was estimated as 1.2-2.5 (equivalent units, ml/g/min.) in dead cortex. The ratio of clearances in H2-Gen to H2-Inh varied in different experiments from 1.0 up to 4.0.(ABSTRACT TRUNCATED AT 250 WORDS)

Structure-function analysis of angiotensin I-converting enzyme using monoclonal antibodies. Selective inhibition of the amino-terminal active site

Angiotensin I-converting enzyme (ACE; kininase II) contains two very similar domains (the NH2- and COOH-terminal domains (N and C domains, respectively)), each bearing an active site. These active sites hydrolyze the same peptides, but do not have the same catalytic properties and substrate specificities. In an attempt to develop domain-specific immunological probes, two series of monoclonal antibodies (mAbs), 19 clones in all, were produced and tested against human ACE. These mAbs recognized at least nine different epitopes within three antigenic regions of the ACE molecule. Testing on wild-type recombinant ACE and several mutants with only one intact domain showed that these epitopes were all located in the N domain. None of the mAbs recognized the C domain. This particular specificity and analysis of results obtained with several polyclonal antibodies to human ACE suggest that ACE immunogenicity is determined mainly by the N domain. Two mAbs (3A5 and i2H5) recognizing epitopes from different antigenic regions of ACE inhibited the enzymatic activity of the N (but not of the C) domain. mAb 3A5 had the same inhibitory potency toward hippuryl-His-Leu, benzyloxycarbonyl-Phe-His-Leu, and angiotensin I hydrolysis, with 50% inhibition achieved at a mAb/ACE molar ratio of 6. mAb i2H5 was roughly three times more effective than mAb 3A5 inhibiting the hydrolysis of benzyloxycarbonyl-Phe-His-Leu and the natural substrates angiotensin I and bradykinin (50% inhibition at a molar ratio of 1-2), but was less effective in inhibiting hippuryl-His-Leu cleavage (50% inhibition at a molar ratio of 22-25), indicating that this substrate interacts with a specific subsite. mAb i2H5 almost completely inhibited the hydrolysis of the luteinizing hormone-releasing hormone by the isolated N domain. Both the primary carboxyl- and amino-terminal cleavages of this peptide were suppressed. This antibody suppressed the primary amino-terminal cleavage of the luteinizing hormone-releasing hormone by wild-type ACE by > 90%, indicating that this particular ACE function is mediated mainly by the N domain active site. These data provide evidence for structural differences between the two homologous domains of ACE despite their high degree of sequence homology and show that monoclonal antibodies are able to distinguish between the two active sites in ACE.

Slightly altered permeability-surface area products imply some cerebral capillary recruitment during hypercapnia

To test the capillary recruitment hypothesis in brain, cerebral blood flow was raised markedly in rats by exposure to 8% CO2 (hypercapnia), and capillary permeability-surface area (PS) products were measured. Local cerebral blood flow (LCBF), volume of radiolabeled blood in parenchymal microvessels (also referred to as the blood space or Vb), plus the local capillary influx rate constants (K1) and PS products of [14C]antipyrine and 3-O-[14C]methyl-D-glucose (3OMG) were estimated in 44 brain areas. Hypercapnia raised PaO2 to 140 mm Hg, elevated LCBF by two- to threefold through out the brain, and increased Vb from 5 to 33% (mean = 22%) in 42 of 44 brain areas; hypercapnia did not, however, alter microvessel hematocrit. With hypercapnia, the influx of antipyrine was increased by 40-65% in all brain areas, and the PS products of antipyrine were elevated from 0-35% (mean = 17%). The PS products of antipyrine plus the parenchymal blood spaces suggest modest (< 30%) capillary recruitment in most brain areas as well as some microvessel dilation, mainly in forebrain gray matter and white matter areas. In contrast, hypercapnia did not appreciably alter K1 nor PS of 3OMG; it slightly but not significantly raised the blood levels of glucose. In view of the blood space and antipyrine evidence for modest capillary recruitment and vasodilation, the lack of change in PS of 3OMG implies that glucose transporter activity was lowered by hypercapnia, an effect similar to that reported for high-dose pentobarbital. Finally, the microvessel hematocrit and 3OMG data suggest that cerebral capillary permeability (P) was not increased by hypercapnia. Overall, hypercapnia seems to increase LCBF mainly by raising the velocity of blood flow; capillary recruitment and dilation appear to play relatively minor roles in this flow increase.

Phosphorylation effects on flanking charged residues. Structural implications for signal transduction in protein kinases

1H-NMR and 31P-NMR spectroscopy were employed to assess the electrostatic consequences of phosphorylation of single and multiple tyrosine residues in peptides derived from the core and tail autophosphorylation regions of the human insulin receptor tyrosine-kinase domain. In both peptides, phosphorylation was accompanied by changes in the resonances from basic side-chains; those from acidic residues were unaffected. Tyrosine phosphorylation caused increases of up to one in the pKa values of histidine residues situated up to eight residues away in the primary sequence. Titration curve analysis by Hill plots suggested some cooperativity of histidine and phosphate ionizations. Behaviour closely analogous to that of the insulin receptor tail peptide was observed during changes in phosphorylation of the intact insulin receptor kinase domain, suggesting that the electrostatic dissemination effects seen for the isolated peptide are retained by the peptide sequence in the context of the much larger protein. Similar changes in the behaviour of basic residues were also observed upon tyrosine phosphorylation of a cdc2-derived peptide, suggesting that this potential of phosphorylation events to propagate directed structural changes may find a widespread utility in the activation of protein kinases and in the transduction of phosphorylation-based signalling.

[Auto-analysis of corneal endothelium with photoelectrical scans and computer]

A quantitative analysis of corneal endothelial cells was made with photoelectrical scans and computer in 67 eyes. No difference was found as regards to the mean cell area and density between the endothelial analysis system and routine square counting. On the other hand, we analyzed corneal endothelial cells between 30 eyes wearing hard contact lens and 30 eyes of age- and sex-matched nonwearing control. The parameters, including cell density individual cell area, area, mean cell area, standard deviation, coefficient of variation of cell size (CV), maximum cell, minimum cell, the ratio of the maximum to minimum cell, and percentage of the hexagoal cells, were automatically displayed. The cell density and mean cell area also showed no significant difference (P > 0.05) between the wearers and nonwearing control, but the CV and the frequency of the hexagonal cells showed significant difference (P < 0.01). The ratio of maximum to minimum cell, the polymegethism and pleomorphism were obviously increased in the wearers. It is highly suggested that computer analysis system is of great value in evaluating corneal endothelial cells.

[Application of nitrous oxide in labor analgesia]

Labor analgesia with nitrous oxide was studied in 34 parturients, and another 50 women taking no drug as the control group. The analgesic effect was satisfactory. By Mulleetr's pain in labor score, 91.18% women had score of 0-1, and their respiratory and circulatory functions were not affected. During inhalational analgesia the parturients remained conscious. Uterine contraction, progress of labor and neonatal Apgar score were not interferred, and postpartum bleeding was not increased. There was no complications in the treatment group. This study suggests that nitrous oxide with enough oxygen inhalation is one of the good drug for obstetric analgesia, but its concentration must be strictly controlled.

Hormonal regulation of insulin-like growth factor II and insulin-like growth factor binding protein expression by breast cancer cells in vivo: evidence for stromal epithelial interactions

Insulin-like growth factors (IGFs) I and II are potent mitogens for breast cancer cells. Their proliferative activity is likely to be influenced by their binding proteins (IGFBPs), a family of newly identified proteins. We report here on the in vivo hormonal regulation of mRNAs for IGF-II and IGFBPs in the N-nitrosomethylurea-induced rat mammary tumor, a well-established model of hormone-responsive mammary cancer. IGF-II mRNA levels tended to decrease in regressing tumors following ovariectomy, and they markedly increased upon reactivation of tumor growth with hormone repletion. Ovariectomy induced a drastic increase in IG-FBP-6 mRNA which was reversible with hormone repletion. Similar but more modest changes were observed with IGFBP-2 mRNA. In contrast, IGFBP-3 and IGFBP-4 mRNAs tended to decrease with ovariectomy and increase with hormone repletion. These latter effects, however, were modest, variable, and not statistically significant. In situ hybridization analysis revealed that IGF-II, IGFBP-5, and IGFBP-6 mRNAs were localized in the stromal component of the tumor, whereas IGFBP-2 mRNA was expressed by epithelial cells. We conclude that hormonal regulation of IGFBP expression is heterogeneous, thus suggesting divergent biological functions for these peptides. Our data also emphasize the importance of potential stromal-epithelial interactions in the control of breast cancer cell proliferation by IGFs.

Virtually unaltered permeability-surface area products imply little capillary recruitment in brain with hypoxia

OBJECTIVE

To test the capillary recruitment hypothesis for the brain with control and hypoxic rats.

METHODS

Local cerebral blood flow (LCBF) was sharply raised by respiring 10% O2 (hypoxia). LCBF as well as local influx rate constants (K1) and permeability-surface area (PS) products of 14C-antipyrine and 14C-3-O-methyl-D-glucose (30MG) were estimated for capillary systems in 44 brain areas.

RESULTS

With this testing, an increase in PS product would be suggestive of capillary recruitment. In all brain areas, LCBF was increased by 30-90% by hypoxia. Hypoxia modestly raised the influx of antipyrine in brain but did not appreciably alter its PS products. With hypoxia, K1's and PS products of 30MG were significantly lowered (5-25%) throughout the brain, and the blood levels of glucose were sizeably raised. The latter increase would diminish the transfer of 30MG across the blood-brain barrier by the hexose transporter because of increased glucose competition. By applying a glucose-concentration correction to the data, the apparent PS product of 30MC for the hypoxic group became equal to that for the controls, which agrees with the antipyrine PS product results.

CONCLUSIONS

Hypoxia, thus, leads to virtually no increase in PS products and no capillary recruitment in brain, and elevates LCBF mainly, perhaps exclusively, by raising the velocity of flow through already perfused capillaries.

[Changes in the extracellular matrix in human mesangial proliferative glomerulonephritis]

A quantitative analysis of the components of glomerular extracellular matrix (ECM) was performed with the immunoperoxidase method (ABC method) and the computer imaging analysis system. The results demonstrate that with the development of mesangial proliferative glomerulonephritis (MsPGN), normal components of glomerular ECM (type IV collagen, laminin, fibronectin) increased markedly. In addition, interstitial collagen (type III collagen) appeared in the expanded mesangial matrix of moderate MsPGN and increased in severe MsPGN, suggesting that MsPGN is linked to the accumulation of ECM, not only the normal components, but also the interstitial collagen.

Pituitary adenylate cyclase activating polypeptide-induced desensitization on growth hormone release from rat primary pituitary cells

Pituitary adenylate cyclase activating polypeptide (PACAP38) stimulated growth hormone release as well as cAMP accumulation in a static rat primary pituitary cell culture in a dose-dependent manner with EC50 values of 1.9 +/- 0.4 nM (n = 13) and 0.9 +/- 0.3 nM (n = 5), respectively. The maximal GH response was observed between 5 to 15 min. Prolonged incubation (3 to 4 hrs) markedly reduced the stimulatory effect of PACAP38. The effect of PACAP38 on GH release was desensitized by pretreatment of the cells with PACAP38 or GRF, but not with PMA. The PACAP38-induced desensitization appeared to be time- and dose-dependent. Somatostatin (20 nM) inhibited PACAP-stimulated GH release through a cAMP-independent pathway.

Proteolytic release of human angiotensin-converting enzyme. Localization of the cleavage site

Angiotensin-converting enzyme (EC 3.4.15.1, ACE) is a transmembrane protein with a short carboxyl-terminal cytoplasmic domain, a 17-amino acid hydrophobic anchor domain, and a large N-terminal extracellular region containing two catalytically homologous domains. An active soluble form of ACE circulates in human plasma and is produced in culture medium of Chinese hamster ovary (CHO) cells transfected with the full-length human ACE cDNA. The mechanism of ACE release in CHO cells involves a post-translational proteolytic cleavage occurring in the carboxyl-terminal region. The carboxyl terminus of the secreted recombinant ACE, AGQR, was established by carboxyl-terminal microsequencing and corresponds to a cleavage site between Arg-1137 and Leu-1138. Two independent studies confirmed this proposed cleavage site: amino acid analysis of a carboxyl-terminal peptide derived from soluble ACE and immunocharacterization of membrane-bound and soluble ACE with antibodies raised against three peptides located along the carboxyl-terminal ACE sequence. In order to assess the importance of Arg-1137, this amino acid was mutated to a glutamine residue. This mutation did not prevent the secretion of ACE, suggesting that the solubilizing enzyme can accommodate this change or can use an alternative cleavage site. Finally, the production of soluble ACE in CHO cells appears to be proportional to the level of cellular ACE, implying that the solubilizing enzyme is not a limiting factor. In addition, the carboxyl-terminal sequence of the human plasma ACE was identified as AGQR, thus supporting the fact that a similar mechanism could operate in human vascular cells.

Nicotine increases microvascular blood flow and flow velocity in three groups of brain areas

To examine the mechanism of local cerebral blood flow (LCBF) elevation, nicotine (1.75 mg/kg sc) was administered to rats, and LCBF plus the distribution spaces of radiolabeled albumin (RISA) and red blood cells (RBC) in parenchymal microvessels were measured throughout the brain. Microvascular blood spaces and transit times were calculated from the data. From 1.5 to 3 min after nicotine administration, LCBF was raised by 40-150% in 16 of the brain areas and unaltered in the remaining 28 areas. The affected structures included parts of the visual-auditory, sensorimotor-cortical, and interpeduncular systems. RBC spaces were not changed by nicotine treatment. RISA and blood spaces were increased slightly but not significantly in some of the LCBF-affected areas but nowhere else. Nicotine seemingly elevates LCBF in the affected areas mainly by increasing linear velocity of flow through the microvascular beds. In agreement with this, mean transit time, which is inversely related to velocity, was decreased from 0.3-0.5 to approximately 0.2 s in the microvascular systems of the nicotine-affected areas.