[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.

Taurine ameliorates chronic streptozocin-induced diabetic nephropathy in rats

We examined the effect of two endogenous antioxidant agents, taurine and vitamin E, on renal function in experimental diabetes. Male Sprague-Dawley rats, rendered diabetic with streptozocin (STZ), were assigned to one of the following groups: 1) untreated; 2) insulin treatment with 6 U Ultralente insulin/day in two doses; 3) taurine supplementation by 1% taurine in drinking water; and 4) vitamin E supplementation at 100 IU vitamin E/kg chow. Animals were kept for 52 wk. The survival rate was similar (70-90%) in all groups except vitamin E-treated animals, of which 84% died by 6 mo. At 52 wk, glomerular filtration rate was elevated in untreated and taurine-treated STZ rats compared with normal or insulin-treated diabetic rats. Taurine supplementation reduced total proteinuria and albuminuria by nearly 50%. This treatment also prevented glomerular hypertrophy, preserved immunohistochemical staining for type IV collagen in glomeruli, and diminished glomerulosclerosis and tubulointerstitial fibrosis in diabetic animals. The changes in renal function and structure in taurine-treated diabetic rats were associated with normalization of renal cortical malondialdehyde content, lowering of serum free Fe2+ concentration, and decreased formation of the advanced glycooxidation products, pentosidine, and fluorescence in skin collagen. Administration of the vitamin E-enriched diet exacerbated the nephropathy in STZ-diabetic rats. In addition, vitamin E supplementation increased serum free Fe2+ concentration, enhanced renal lipid peroxidation, and accelerated the accumulation of advanced glycosylation end products (AGEs) in skin collagen. We conclude that administration of taurine, but not vitamin E, to rats with STZ-diabetes ameliorates diabetic nephropathy. The beneficial effect of taurine is related to reduced renal oxidant injury with decreased lipid peroxidation and less accumulation of AGEs within the kidney.

DNA condensation by cobalt hexaammine (III) in alcohol-water mixtures: dielectric constant and other solvent effects

DNA molecules condense into compact structures in the presence of a critical concentration of multivalent cations. To probe the contribution of electrostatic forces to condensation, we used mixtures of water with methanol (MeOH), ethanol (EtOH), and isopropanol (iPrOH) to vary the dielectric constant epsilon from 80 to 50. The condensation of pUC18 plasmids by hexaammine cobalt (III), Co(NH3)(3+)6, was monitored by total intensity and dynamic light scattering, electron microscopy, and CD. The total scattering intensity increased as epsilon went from 80 to 70, and the decreased as epsilon decreased further. Ultraviolet spectrophotometry confirmed that the loss of intensity at low epsilon was not due to the particles' settling out of solution. The rate as well as the extent of condensation increased as epsilon was lowered from 80 to 70, and also depended on the species of alcohol (MeOH < EtOH < iPrOH). The hydrodynamic radii RH of the particles, however, remained roughly the same at 300-350 A and was independent of the species of alcohol. RH increased below epsilon = 70. The critical concentration of Co(NH3)6(3+) required to induce DNA condensation decreased from 21 microM to about 16 microM as the dielectric constant decreased from 80 to 70, and decreased moderately with the nonpolarity of the alcohol. The fraction of DNA charge neutralized at the onset of DNA condensation was calculated by a modification of Manning's two-variable counterion condensation theory to be 0.90 +/- 0.01, independent of epsilon. By electron microscopy we observed that the condensed particles changed from about 93% toroids at epsilon = 80 to 89% rods at epsilon = 70 and 98% rods at epsilon = 65. At epsilon lower than 65, DNA collapsed into a network of multistranded fibers. The morphology of condensed DNA particles, whether toroids, rods, or fibers, was independent of the alcohol species. CD spectra in ethanol-water mixtures indicated that both closed circular and linearized plasmids were in the B conformation when condensed with Co(NH3)6(3+) at epsilon > or = 70, although the closed circular molecules exhibited a weak psi-DNA spectrum. A transition from the B to A form took place between epsilon = 70 and 60, well above the normal dielectric constant of epsilon = 40 for this transition, indicating that ethanol and Co(NH3)6(3+) synergistically promote the B-A transition. We interpret these results to mean that alcohols have both electrostatic and structural effects on DNA, leading to three regimes of condensation. At the lowest alcohol concentrations the B conformation is stable and condensation is relatively slow, allowing time for the packing adjustments necessary to form toroids.(ABSTRACT TRUNCATED AT 400 WORDS)

Wingless and patched are negative regulators of the morphogenetic furrow and can affect tissue polarity in the developing Drosophila compound eye

In the developing Drosophila compound eye, a wave of pattern formation and cell-type determination sweeps across the presumptive eye epithelium. This ‘morphogenetic furrow’ coordinates the epithelial cells' division cycle, shape and gene expression to produce evenly spaced neural cell clusters that will eventually form the adult ommatidia. As these clusters develop, they rotate inwards to face the eye's equator and establish tissue polarity. We have found that wingless is strongly expressed in the dorsal margin of the presumptive eye field, ahead of the morphogenetic furrow. We have shown that inactivation of Wingless results in the induction of an ectopic furrow that proceeds ventrally from the dorsal margin. This ectopic furrow is normal in most respects, however the clusters formed by it fail to rotate, and we propose a two-vector model to account for normal rotation and tissue polarity in the retina. A second consequence of this inactivation of Wingless is that the dorsal head is largely deleted. We have also found that patched loss-of-function mosaic clones induce circular ectopic morphogenetic furrows (consistent with the observations of other workers with the hedgehog, and PKA genes). We use such patched induced furrows to test the two-vector model for cluster rotation and tissue polarity.

Experimental study of fat embolism syndrome

To find the diagnostic methods for subclinical stage fat embolism syndrome (FES), we established an experimental animal model, using fat intravenous injection. The fat was obtained from the long bone marrow cavity of homologous dogs. Fourteen healthy mongrel dogs received 0.7 ml/kg fluid marrow fat injection and all of them developed FES within 48 hours. The blood samples collected from the pulmonary vessels by floating catheter and peripheral vein at different time intervals were subjected to blood gas analysis and were frozen sectioned rapidly. The sections were stained with oil red 'O'. Positive result was seen 2 hours after fat injection in both pulmonary and peripheral blood. Computer image analysis showed that the number and diameter of fat droplets in pulmonary vascular blood were obviously higher and larger than those in peripheral vein blood. These findings were correlated well with blood gas changes and clinical features. The demonstration of fat droplets from pulmonary or peripheral blood by oil red 'O' staining combined with blood gas changes (PaO2 < 7.99 kPa, P(A-a)O2 > 6.09 kPa) may be rapid and specific for early diagnosis of FES. In the treatment of FES, dexamethason can stabilize the cellular membranes and inhibit the neutrophil response to fatty acid and the release of phospholipase A2, arachidonic acid and platelet aggregation.

[A modified esophagogastrostomy: report of 528 patients]

The nearby tissues were used to cover the esophagogastric anastomotic stoma in 528 patients with esophageal and cardiac cancer undergoing resection. After interrupted suturing of the whole layer of esophagus and stomach, the paracervicalis was anastomosed with the capsule of the thyroid gland to strengthen the anterior wall of the anastomotic stoma. In case the anastomosis is done alove the arch of aorta, a flap of pedicled plewa is produced to cover the upper frigonum. The lower ligamentum pulmonale was used to coner the anastomosis when it is performed subaoticolly. No anastomotic leakage and stenosis were found in 528 patients in the follow-up of 2-5 years.

Promoters of the phr gene in Escherichia coli K-12

We have identified two promoters of the Escherichia coli phr gene by DNA deletion mapping, S1 mapping of transcripts and sequence homology. The weaker promoter, P2, located approximately 530 bp upstream from the start codon, extends beyond the previously known nucleotide sequence. The stronger, P1, lies 90 bp from the gene and is distinct from three previously described promoter-like sequences nearby. beta-Galactosidase production from a plasmid-borne gene, promoted by a synthetic copy of P1, increases after DNA damage, but the increase does not depend on the SOS-box-like sequences normally present in the vicinity of P1. Induction still requires intact recA and lexA genes, and also intact sulA.

Regulation of Caenorhabditis elegans degenerin proteins by a putative extracellular domain

BACKGROUND

Rare, dominant mutations in the degenerin genes of Caenorhabditis elegans (deg-1, mec-4 and mec-10) cause neuronal degeneration. The extensive sequence similarity between degenerins and mammalian genes that encode subunits of the amiloride-sensitive sodium channel from kidney, colon and lung suggests that the C. elegans degenerins form ion channels. As mec-4 and mec-10 are needed for the reception of gentle touch stimuli, they may contribute to a mechanosensory ion channel. All the dominant degeneration-causing mutations in the C. elegans degenerin genes affect equivalent residues in a hydrophobic region that is structurally similar to the H5 domain of several ion channels, and so could form the channel lining. Increased channel activity may underlie the resulting degeneration, in which the affected cells vacuolate and swell.

RESULTS

We now demonstrate that a missense change in a predicted extracellular region of the proteins encoded by deg-1 and mec-4 causes cell death similar to that caused by the dominant mutations. The missense mutation lies within a 22 amino-acid region found in all the C. elegans degenerins for which the sequences have been published, but not in the similar mammalian proteins. Deletion of nine amino acids surrounding the mutation site in mec-4 also causes neuronal degeneration. The degeneration-causing mutations in either the predicted pore-lining or the predicted extracellular regions of deg-1 are suppressed by additional, dominantly acting mutations that substitute larger for smaller residues within the channel lining.

CONCLUSIONS

Our data suggest that the putative extracellular domain negatively regulates degenerin activity, perhaps by gating the channel. As this region is only found in the C. elegans proteins, it may allow more rapid regulation of the nematode channels, which may be needed for them to function in mechanosensation. The suppressor mutations, by adding larger amino acids to the putative pore lining, could prevent degeneration by blocking the pore of a multisubunit channel.

Condensation of plasmids enhanced by Z-DNA conformation of d(CG)n inserts

DNA molecules collapse into compact structures in the presence of multivalent cations. To probe the possible importance of supercoiling and conformational effects, pUC18 plasmids (2686 bp) were modified by inserting 12-bp and 20-bp alternating d(CG)n sequences, which are capable of converting to a left-handed Z-conformation under appropriate conditions, into the polycloning region. Condensation was induced by rapid addition of hexaammine cobalt(III) [Co(NH3)6(3+)] and monitored by laser light scattering and electron microscopy. Light scattering shows that plasmids with longer d(CG)n inserts condense more extensively at natural superhelical densities. Electron microscopy indicates that the morphological distribution of condensed d(CG)n-containing plasmids changes as a function of Co(NH3)6(3+) concentration. At lower Co(NH3)6(3+) concentration, the proportion of rods is higher, and at higher Co-(NH3)6(3+) concentration, most of the condensates have the form of toroids. In addition, the inner radii of the toroids are much smaller relative to condensed pUC18 under the same conditions. Enzymatic analysis and chemical probing show that the d(CG)n inserts in naturally supercoiled plasmids have extensively converted from B-form to Z-form in the presence of Co(NH3)6(3+) at the upper range of concentrations under which condensation occurs. To determine whether the enhanced condensation of d(CG)n-containing plasmids results from the change of superhelical density due to the B-Z transition, we treated wild-type pUC18 molecules with topoisomerase I and varying amounts of ethidium bromide to generate a range of supercoil densities. Light scattering indicates that supercoiling did not affect the condensation process.(ABSTRACT TRUNCATED AT 250 WORDS)

Novel furostanol glycosides from Allium macrostemon

Further studies by means of preparative HPLC led to the isolation of two new furostanol saponins, macrostemonosides G (1) and I (3), along with an artifact, macrostemonoside H (2) from the bulbs of Allium macrostemon Bunge. On the basis of chemical evidence and spectral analyses (1H-,13C-NMR,1H-1H COSY,1H-13C COSY, HMBC and FAB-MS), the structure of 1 was established as 26-O-beta-D-glucopyranosyl-22-hydroxy-5 beta-furost-25(27)-ene-3 beta,12 beta,26 triol 3-O-beta-D-glucopyranosyl(1-->2)-beta-D-galactopyranoside and 2 as the 22-methoxy derivative of 1; 3 was deduced to be 26-O-beta-D-glucopyranosyl-22-hydroxy-5 beta-furost-25(27)-ene-12-one-3 beta,26- diol 3-O-beta-D-glucopyranosyl(1-->2)-beta-D-galactopyranoside. Preliminary pharmacological tests showed that macrostemonoside G (1) could inhibit ADP-induced human platelet aggregation in vitro (IC50 = 0.871 mM).

Gel electrophoresis measurement of counterion condensation on DNA

We used agarose gel electrophoresis to measure the effective charge neutralization of DNA by counterions of different structure and valence, including Na+, Mg2+, Co(NH3)3+6, and spermidine3+, which competed for binding with an excess of Tris acetate buffer. Linear DNA molecules ranged in size from 1 to 5 kilobases, and supercoiled plasmid pUC18 was also measured. In all cases, the results were in good agreement with theoretical predictions from counterion condensation theory for two-counterion mixtures.

[Experimental comparison of the analgesic action of Aconitum and its processed products]

This paper deals with the effects of crude Aconitum and Aconitum processed by a new method of moistening and steaming, and by method of pharmacopoeial stipulation on the analgesic action with writhing test and hot plate test in mice. The result shows that the Aconitum processed by new method No 1, which applies moistening in water for 48h and then heating with high pressure steam (68.65kPa, 115 degrees C) for 2h has an advantage over that processed according to pharmacopoeial routine (P < 0.05).

[Treatment of extensive deep burn of scalp with full-thickness necrosis of calvarial bone]

From 1990 to 1993 eight patients suffering from extensive deep burn of scalp with full-thickness necrosis of calvarial bone were treated. The intra-cranial damage following electrical injury or prolonged contact with heat source, and the extent of skull necrosis were delineated by CT and bone scanning. Primary coverage of the exposed calvarial bone using musculo-cutaneous flap or free skin flap was done, leaving the necrosed skull in situ to serve as a scaffold of "creeping substitution" for bone regeneration. Primary healing of the wound was achieved in four cases. Three cases required an average of 2.6 times of curettage or excision of the infected bone. None of the cases required a late reconstruction of the skull in this group.

Condensation of supercoiled DNA induced by MnCl2

Multivalent cations condense DNA in vitro, but it had been thought that a valence of at least + 3 was required in aqueous solution. We have found that Mn2+ can produce toroidal condensates of supercoiled plasmid DNA, but not of linearized plasmid. Mg2+ does not cause condensation, and neither MgCl2 nor NaCl can negate the effect of MnCl2, indicating that the condensation mechanism with Mn is not primarily electrostatic. Supercoiled MnDNA is more extensively digested than the linear form by S1 nuclease. Supercoiling appears to cooperate with Mn2+ in stabilizing helix distortions and also provides a "pressure" that enhances lateral association.

spitz, a Drosophila homolog of transforming growth factor-alpha, is required in the founding photoreceptor cells of the compound eye facets

Cell type specification and differentiation in the developing Drosophila compound eye begins in the morphogenetic furrow. In the furrow, cells are organized into evenly spaced preclusters and there is a synchronized arrest of the cells' mitotic cycle in G1. We report that recessive spitz loss-of-function mutations affect compound eye development. Spitz is homologous to the human transforming growth factor-alpha. In mosaic clones, spitz function is required in the first photoreceptor cells to differentiate for normal ommatidial development. spitz loss-of-function mutations are dominant suppressors of EgfrE gain-of-function mutations of the epidermal growth factor-receptor gene. These data suggest that the spitz product is a precluster promoting factor. spitz transcription increases abruptly in the morphogenetic furrow, the obverse of Egfr expression. We present a model for the expression of, and cellular requirement for, this growth factor homolog.

[Determination of alkaloids and comparison of the acute toxicity of differently processed products of the seeds of Strychnos nux-vomica L]

This paper deals with the extraction, determination and identification of the alkaloids in differently processed products of the seeds of Strychnos nux-vomica. The relationship between processing methods and toxicitys is discussed according to the comparison of acute toxicity.

Vesicles and mixed micelles in hypothyroid rat bile before and after thyroid hormone treatment: evidence for a vesicle transport system for biliary cholesterol secretion

Hypothyroid rats show reduced secretion of biliary lipids, especially cholesterol. Secretion of biliary cholesterol is markedly augmented to levels above euthryroid beginning 12-24 h after administration of thyroid hormone. In the current studies, bile from hypothyroid and triiodothyronine-treated chronic bile-fistula rats was analyzed for vesicles and mixed micelles by metrizamide gradient ultracentrifugation. For euthryoid and hypothyroid animals, less than 12% of biliary cholesterol was in a vesicle gradient fraction. After treatment with triiodothyronine, biliary cholesterol increased markedly, and 50% of total cholesterol, 60% of excess cholesterol secreted, appeared in the vesicle fraction. Triiodothyronine stimulation of vesicle secretion resulted in cholesterol-rich vesicles (cholesterol:phospholipid ratio rose from less than 0.1 to 0.56), but no change in the distinct fatty acid composition of vesicle phospholipids. The microtubule inhibitor colchicine, given 12 h after triiodothyronine, prevented subsequent increase in cholesterol secretion in the form of vesicles. These studies, in a model that allows rapid changes in biliary lipid secretion, support the hypothesis that an important component of cholesterol and phospholipid secretion into bile involves microtubules and may involve a vesicle pathway.

PfEMP3 and HRP1: co-expressed genes localized to chromosome 2 of Plasmodium falciparum

A malarial protein, Plasmodium falciparum erythrocyte membrane protein 3 (PfEMP3), has been recently characterized as a high-molecular-mass component (approx. 315 kDa) localized to the erythrocyte membrane of knob-bearing (K+), cytoadherent (C+) mature stages of P. falciparum-parasitized erythrocytes (PE) [Pasloske et al., Mol. Biochem. Parasitol. 59 (1993) 59-72]. Knobless (K-), non-cytoadherent (C-) parasites of the same strain were shown to lack the PfEMP3 gene. In view of the biological importance of the knobby and cytoadherent phenotypes with regard to parasite virulence, we extended the analysis of PfEMP3 and its gene product to other K+/K- and C+/C- parasites. Previously, other studies have shown that the malarial protein, knob-associated histidine-rich protein 1 (HRP1), is also strongly correlated with knob expression. Here, we show that PfEMP3 and HRP1 were absent from all the K- parasites tested, including the Palo Alto (PA) K-C+ strain. This result demonstrates that PfEMP3 and HRP1 are not essential for cytoadherence. PfEMP3 was localized to chromosome 2 of the K+ parasites, within no more than 130 kb of HRP1, between the telomere and HRP1. Stage-specific analysis of the mRNA for HRP1 and PfEMP3 indicated maximal transcription of the genes in ring-stage parasites, with little or no mRNA present during the mature parasite stages. Analysis of PfEMP3 and HRP1 by immunofluorescence assay (IFA) revealed identical staining patterns of fixed PE at all stages of the asexual life cycle. Hence, PfEMP3 and HRP1 are adjacent to each other in chromosome 2, co-expressed temporally and their gene products co-localized to the PE membrane.

[Experimental comparison of the toxicity of radix Aconity Kusnezoffii and processed radix Aconity Kusnezoffii by different methods]

This paper deals with the effects of Radix Aconity Kusnezoffii and Radix Aconity Kusnezoffii processed by a new method of moistening and steaming, and by pharmacopoeial routine on acute toxicity, cardiac rhythm and respiration. The result shows that the Radix Aconity Kusnezoffii processed by new method No 1., which applies moistening in water for 48h and then heating with high pressure steam (68.65kPa, 115 degrees C) for 2h, has the advantages of lower toxicity, and lesser inhibitory effect on cardiac rhythm and respiration.

A perceptual study of source coding of Fourier phase and amplitude of the linear predictive coding residual of vowel sounds

A practical question in a Fourier transform coding of speech signals is to what accuracy their amplitude and phase spectra have to be represented without perceptible distortions. In this paper a concern is with the audibility of quantization noise signals which are produced by quantizing the amplitude and phase spectra of vowel sounds. Experiments show that the detection of the noise targets with maskers of a low fundamental frequency is determined mainly by the sharpest temporal resolution of the auditory system in the high-frequency region. For maskers of a high fundamental frequency the detection is determined mainly by the sharpest spectral resolution in the low-frequency region. Noise targets with global random phase and amplitude are relatively more difficult to detect than those produced by a local randomization. Local random phase noise targets are generally more detectable than those produced by local amplitude randomization. The relative importance of phase and magnitude spectra in the Fourier transform coding is strongly dependent on the fundamental frequency of the vowel sounds and the window size used in the short-time Fourier analysis.

[Haemorrheological effects of different processed products of radix Aconiti Kusnezoffii on animal model with syndrome of "accumulation of cold and blood stasis"]

The effects of Radix Aconiti Kusnezoffii processed by moistening in combination with steaming method and by pharmacopoeial method as well as of the crude drug on haemorrheological nature and the plasma fibronogen content and platelet aggregation rate in the rat model with syndrome of "accumulation of cold and blood stasis" were studied, the result shows that the product processed by moistening in combination with steaming works best.

Pathological changes of the retrosplenial cortex in senile dementia of Alzheimer type

Six brains of patients aged from 71 to 85 years of clinically and pathologically diagnosed senile dementia of Alzheimer type and six brains of age-matched controls (55-91 years) was used for this study. The retrosplenial cortex of these brains have been examined by Gallyas and Campbell-silver impregnations. Gallyas preparation showed a number of intracellular pathological changes in retrosplenial cortex of demented individuals. Although the neuritic plaques, the neurofibrillary tangles and neuropil threads were seen in all lamina, their high density appear in lamina IIIa and V of retrosplenialis lateralis (Rsl), retrosplenialis intermedia (Rsi), retrosplenialis media (Rsm) and parasplenialis (Ps). The retrosplenial cortex of non-demented individuals was almost devoid of neurofibrillary changes. The retrosplenial cortex of all demented individuals and one age-matched controls showed a large amount of amyloid deposits in Campbell preparation, while two non-demented individuals showed only small amounts of amyloid. The amyloid deposition can be classified into three types. The packing of Campbell-argyrophilic material show area-specific and lamina-specific distribution.

The segment polarity gene hedgehog is required for progression of the morphogenetic furrow in the developing Drosophila eye

Cell-type specification in the Drosophila compound eye begins at the morphogenetic furrow. The furrow sweeps across the developing eye epithelium and is coincident with four classes of cellular events: coordinated changes in cell shape, changes in gene expression, synchronization of the cell cycle, and the specification of a regular array of ommatidial founder cells. The molecular mechanisms that induce these events in the developing eye have hitherto been unknown. We identify here a gene specifically required for furrow progression, hedgehog (hh). We show that hh expression posterior to the morphogenetic furrow is continuously required for its progression. We propose that forward diffusion of hh protein induces anterior cells to enter the furrow.

Interdigital soft tissue separation induced by retinoic acid in mouse limbs cultured in vitro

The temporal pattern of separation of the soft tissue between mouse digits was examined in an organ culture model system. Mouse limbs of different gestational age were cultured in vitro and the pattern of separation of the digits characterized. By gestational day 12.5 (E12.5) the limbs were committed to undergo separation of the soft tissue in the interdigital space when cultured in vitro. Prior to E12.5 digital separation did not occur and the limb tissues were not committed to this process. The addition of 10(-7) M retinoic acid (RA) to the media of E12 limbs was capable of inducing digit separation in the uncommitted limbs. Both the soft and hard tissue development of digits formed in vitro for either committed limbs or uncommitted limbs induced with RA was similar to the in vivo pattern.

In vitro protein engineering using synthetic tRNA(Ala) with different anticodons

The use of synthetic tRNA for in vitro protein engineering was tested in a coupled transcription/translation system prepared from Escherichia coli. DNA sequences similar to the natural tRNA(Ala/UGC) gene from E. coli but with different anticodons were synthesized in vitro, cloned into a DNA plasmid, and then transcribed in vitro with T7 RNA polymerase. The UGC alanine anticodon was changed to CUA corresponding to the UAG stop codon, CCU corresponding to the rarely used AGG arginine codon, and two four-nucleotide anticodons used to suppress stop codons. Bacterial dihydrofolate reductase was the test protein. Its cloned coding sequence was mutagenized at the GUG codon for valine-75 to correspond to the anticodons of the tRNA constructs, and then the plasmids were used to direct the synthesis of dihydrofolate reductase in the coupled transcription/translation system containing the corresponding synthetic tRNA. The results indicate that all four synthetic tRNAs were functionally active in the synthesis of full-length, enzymatically active dihydrofolate reductase protein.

Endogenous epidermal growth factor regulates limb development

Mutations associated with genes of the EGF superfamily are implicated in limb malformations. To evaluate the potential role of EGF-mediated signal transduction in the control of early mammalian limb development, we developed a simple in vitro system which is permissive for morphogenesis and cytodifferentiation in serumless, chemically defined medium. Our experimental strategy was to ascertain if the EGF precursor gene was transcribed and translated into potentially bioactive growth factor. EGF mRNA transcripts are expressed in Swiss Webster mouse embryonic (42-44 somite pairs) forelimbs as determined by mRNA phenotyping. EGF transcripts are translated into precursor EGF polypeptides which were localized to limb covering epithelium and the chondrogenic mesenchymal cell lineages. EGF immunostaining patterns suggested a paracrine type of regulation for the cartilage blastema associated with forelimb development. To test whether EGF effects the timing and positional information required for limb-specific cartilage morphogenesis, we employed tyrphostin (RG 50864) which inhibits EGF receptor kinase activity in a concentration-dependent manner and severely retards limb development. These findings support our hypothesis that endogenous EGF or EGF-like proteins provide signaling for the size and shape of discrete forelimb cartilage formations during mouse embryonic morphogenesis.

Sister chromatid fusion initiates amplification of the dihydrofolate reductase gene in Chinese hamster cells

We have utilized a dihydrofolate reductase (DHFR) probe in combination with selected probes from other positions along the 2q chromosome arm in a two-color fluorescence in situ hybridization analysis of early DHFR gene amplification events in CHO cells. These studies show clearly that the most frequent initiating event is the formation of a giant inverted duplication, resulting from chromosome breakage and terminal fusion or a reverse unequal sister chromatid exchange. The dicentric chromosomes thus formed initiate bridge/breakage/fusion cycles that appear to mediate subsequent amplification steps to higher copy number.

An improved microassay for Plasmodium falciparum cytoadherence using stable transformants of Chinese hamster ovary cells expressing CD36 or intercellular adhesion molecule-1

Stable transformants of Chinese hamster ovary (CHO) cell lines expressing high levels of human CD36 or intercellular adhesion molecule-1 (ICAM-1) have been produced as target cells for cytoadherence of Plasmodium falciparum-infected erythrocytes. An improved adherence microassay has been designed using small sample volumes and allowing convenient and reliable measurements on a large number of samples. The assay can be used both with purified proteins spotted on plastic and with the stably transformed CHO cell lines. The same assay plate can be evaluated either microscopically or by scintillation counting after use of 3H-hypoxanthine-labeled parasites. Using the microassay, functional expression of the transfected receptor molecules on CHO-CD36 and CHO-ICAM was confirmed using parasites with different cytoadherence phenotypes and cytoadherence inhibition experiments with a panel of anti-CD36 antibodies. The use of isolates from The Gambia confirmed the applicability of these assays for laboratory studies of these isolates.

[Study on lignans from Diphylleia sinensis]

A new lignan along with eight known lignans and a flavonoid were isolated from the rhizomes of Diphylleia sinensis Li.. Their structures were elucidated on the basis of chemical and spectral analysis. The new lignan, compound IX, was named as picropodophyllin-1-ethyl ether (IX). The eight known lignans were identified as podophyllotoxin (I), isopicropodophyllone (II), dehydropodophyllotoxin (III), diphyllin (IV), picropodophyllin (V), podophyllotoxone (VI), 4'-demethylpodophyllotoxin (VII) and picropodophyllin glucoside (VIII). Compounds II, VI, VII and VIII were found for the first time from the rhizome of this plant. The flavonoid was identified as kaempferol.

[Changes in lymphocyte beta-receptor density in patients with heart failure before and after metoprolol or captopril administration]

Human lymphocyte beta-receptor density in heart diseases with various degrees of heart function of 41 cases was determined. beta-receptor density and ejection fraction in congestive heart failure (CHF) before and after conventional therapy with small dose of beta-blocker (metoprolol) or captopril were compared. The aim was to clarify the action and safety of beta-blocker in the treatment of CHF. The results revealed that there was no statistical difference between beta-receptor density in CHF with cardiac function of degree I and II (516.57 +/- 85.93 fmol/10(7) cells, mean +/- s) and in normal controls (576.56 +/- 97.18 fmol/10(7) cells, P > 0.05), while beta-receptor density in CHF of degree III and IV was much lower than that in normal controls (decreased by 50%). There was no statistical difference of beta-receptor density between rheumatic heart disease and cardiomyopathy. Metoprolol up-regulated beta-receptor density from 302.40 +/- 100.91 to 459.60 +/- 174.34 fmol/10(7) cells (P < 0.05), but no change was observed after treatment by captopril. Ejection fraction was increased in both groups (P < 0.01). The results revealed that beta-receptor density was decreased in certain kinds of CHF but no relationship was observed between CHF of different etiology. beta-receptor density was up-regulated by beta-blocker, thus it indicates that it is rational to use beta-blocker for the treatment of certain kinds of CHF. And the use of small dose of beta-blocker with conventional therapy of heart failure might reduce the negative inotropic action of the former.

Predicting multipulse laser-induced failure for molybdenum metal mirrors

In combination with known thermomechanical-fatigue data for Mo, we have conducted transient photothermal deflection (TPD) measurements to develop a model for the multipulse laser damage of Mo mirrors to predict their lifetimes. In laser-damage experiments to verify the model, Mo mirrors were irradiated with 10-ns Nd:YAG laser pulses at 1064 nm at a 10-Hz repetition rate. Digitized TPD waveforms indicated peak surface angular deflection that could then be converted into surface displacement. Numerical modeling of the vertical heat distribution enabled the peak surface-deflection signal to be converted into peak surface temperature. The thermomechanical model was verified by both the experimental and the numerical results. Conventional mechanical-fatigue data for Mo were used to derive a predictive equation for the laser-accumulation lifetime of Mo mirrors. Experiments were performed with 1-10(4) pulses per site, yielding laser-damage thresholds and accumulation curves. The accumulation behavior predicted from measurements of mechanical fatigue was in excellent agreement with the measured behavior. Thus a single-pulse TPD measurement of peak deformation at a subthreshold laser fluence, in conjunction with mechanical-fatigue data, may be used to estimate the safe operating fluence for a component in a multipulse laser environment.

Combined localized current field hyperthermia and irradiation for intraocular tumors

Ten patients with large melanomas and one patient with recurrent retinoblastoma were treated with combined localized current field (LCF) hyperthermia and iodine 125 irradiation delivered by episcleral plaque. Tumors were heated to 43 degrees to 45 degrees C for 28 to 45 minutes. Localized current field hyperthermia when combined with irradiation appeared to induce rapid tumor necrosis. One eye enucleated 17 hours after treatment showed only focal necrosis of the melanoma, while another eye demonstrated extensive necrosis 60 hours after treatment. In all remaining eyes, tumor regression occurred within the first month of treatment. Complications included cataract formation in six eyes, hemorrhagic retinal detachment in five eyes, and phthisis in two eyes. Complications from combined therapy of large intraocular tumors in this series appeared to result from the rapid necrosis of the tumor and secondary intraocular inflammation. Intraocular temperature dosimetry measurements demonstrated a temperature gradient of not more than -0.23 degrees C/mm-1 per axial millimeter from the episcleral plaque surface to the apex of the tumor. The authors believe that LCF hyperthermia could be a suitable means of application of hyperthermia in patients with intraocular tumors if further modifications were performed to reduce ocular complications.

[Comparison of phospholipids in crude drug of Polygonum multiflorum Thunb. and its processed products]

This paper reports the qualitative analysis and content determination of phospholipids in the crude drug of Polygonum multiflorum and its four processed products by TLC. The content in the crude drug is 3.49% and in the products processed with black soybean and millet wine 1.62% and 1.82% respectively.

Origins of replication: timing and chromosomal position

Several new methods have been used to localize replication initiation sites in mammalian chromosomes. The results of these studies argue strongly for the presence of defined sequence elements that function much like the origins in the genomes of simple microorganisms. However, relatively disparate results from in vivo and in vitro studies suggest that initiation reactions in mammalian chromosomes may have unique features, possibly related to a more complicated chromosomal architecture.

Acute effects of oral pyridostigmine bromide on conditioned operant performance in rats

Pyridostigmine bromide (Pyr), the current drug of choice in the management of myasthenia gravis, has been suggested for use in Alzheimer's dementia, and as a prophylactic treatment for intoxication with organophosphate cholinesterase inhibitors. The present study was undertaken to evaluate the dose-response and time-course effects of acute oral administration of Pyr over a broad dose range (3-40 mg/kg) on the lever pressing of rats maintained under a multiple fixed-ratio (FR-20) time-out schedule of reinforcement for water reward. The drug produced a dose-dependent biphasic response depression in the overall rate of FR responding. Low doses of Pyr (less than or equal to 12 mg/kg) that caused no gross signs of toxicity only moderately decreased rates of responding, primarily due to a decrease in response rates. Whereas high doses of Pyr (greater than 24 mg/kg) which produced overt signs of peripheral cholinergic intoxication markedly suppressed overall responding, primarily due to cessation of responding. The lowest effective dose of performance disruption was 6 mg/kg, and the ED50 was calculated as 23.3 (17.9-28.7) mg/kg. The time-course data of performance disruption showed that low doses of Pyr (less than or equal to 12 mg/kg) had an onset latency within 40-80 min and a duration of 20-80 min, whereas high doses (greater than or equal to 24 mg/kg) had an onset latency of 20-40 min and a duration greater than 80 min. These results suggest the recommended human therapeutic or prophylactic regimen of 30-120.mg Pyr, orally taken each 8 hours, might adversely affect behavioral performance.

Simplified analysis and structural design for ridge mos optical waveguides

A simplified method is presented for analyzing the optical characteristics of ridge MOS optical waveguides. Equations are derived for calculating the effective refractive indices and the absorption loss coefficients of the E(x)(pq) modes. The computations are performed for air-Au-air/SiO(2)/GaAs/AlGaAs ridge MOS waveguides. To achieve single-mode propagation with low absorption loss, appropriate selection of the structural parameters for this kind of waveguide is discussed.

The IS10 antisense RNA blocks ribosome binding at the transposase translation initiation site

Transposase (tnp) expression from insertion sequence IS10 is controlled, in part, by an antisense RNA, RNA-OUT, which pairs to the translation initiation region of the tnp mRNA, RNA-IN. Genetic experiments suggest that control occurs post-transcriptionally. Here, we present evidence that bears on the control mechanism. Specific ribosome binding at the tnp translation initiation site is demonstrated in vitro. Two mutations that alter tnp translation in vivo are shown to have corresponding effects in vitro. Most importantly, RNA-OUT/RNA-IN pairing is shown to block ribosome binding. In conjunction with the work described in the accompanying paper, we propose that inhibition of ribosome binding also occurs in vivo, and that it is sufficient to account for control. Implications for translational control in analogous systems are discussed.