The chsA gene from Aspergillus nidulans is necessary for maximal conidiation

A fragment from the open reading frame of the cloned chsA gene from Aspergillus nidulans was deleted and replaced with the argB gene. The resulting construct was used to replace the wild-type chsA gene in an argB deletion strain. The growth and morphology of the vegetative hyphae from the resulting chsA disruptant strain were indistinguishable from those of a wild-type strain but the chitin content of the hyphae from the disruptant was reduced to approximately 90% of that of wild-type. The disruptant showed reduced ability to produce the asexual spores (conidia) that are formed by differentiated aerial hyphae called conidiophores. The ability to form undifferentiated aerial hyphae was not impaired in the disruptant. The conidiophores and conidia produced by the disruptant were indistinguishable from those of wild-type. Conidium formation by the disruptant grown on a variety of media was reduced to about 30% of the wild-type. A chsE null strain did not show a defect in conidiation but a strain in which both chsA and chsE were inactivated produced about 3% of the conidia of wild-type. That finding supports the hypothesis that chsA and chsE encode a partially redundant function necessary for conidiophore development.

Assessment of iron oxide particles (AMI 227) and a gadolinium complex (Gd-DOTA) in dynamic susceptibility contrast MR imagings (FLASH and EPI) in a tumor model implanted in rats

The objective of our study was to assess the feasibility of dynamic susceptibility contrast MR technique after bolus injection of SPIO and Gd-DOTA in a tumor model implanted in rats. Tumors were subcutaneously implanted in 24 rats. A FLASH sequence and EPI were evaluated. Different doses of AMI 227 and Gd-DOTA were assessed. Mean signal intensity vs. time curves were plotted. Well-shaped curves of the first pass of the contrast agent were only obtained with Gd-DOTA. According to these results it appears difficult to assess tumor blood volume with USPIO dynamic susceptibility contrast imaging.

Comparison of iron oxide particles (AMI 227) with a gadolinium complex (Gd-DOTA) in dynamic susceptibility contrast MR imagings (FLASH and EPI) for both phantom and rat brain at 1.5 Tesla

The goal of the study was to compare, in phantom and normally perfused rat brain tissue, a superparamagnetic iron oxide particle-based contrast agent (AMI 227) with a low-molecular-weight gadolinium chelate, gadolinium tetraazacyclododecanetetraacetic acid (Gd-DOTA), in two susceptibility contrast magnetic resonance imaging (MRI) modes [fast low-angle shot sequence (FLASH) and echoplanar imaging (EPI)]. A phantom consisting of dilution series of both contrast agents was manufactured. Dilutions were obtained with isotonic serum from the available agent solutions (0.5 mmol Gd/mL Gd-DOTA; 350 mumol Fe/mL AMI 227). Eighteen rats were studied. Contrast agent (0.1 mL) was bolus injected in each rat, and dynamic MRI was performed (first pass of the contrast agent) in rat brain. The doses of AMI 227 injected were extrapolated from the phantom experiment: 0.2 mmol/kg body weight of Gd-DOTA and 7, 14, and 28 mumol Fe/kg body weight of AMI 227 were injected. For both sequences, signal-to-noise ratios (S/N) were measured on each tube of the phantom and on rat brain from each image of the dynamic imaging. S/N was plotted versus contrast dilution (phantom) and versus time (rats). In the FLASH sequence, a well-shaped curve (S/N decrease, S/N peak decrease, S/N increase) of the first pass of the contrast agent was demonstrated for Gd-DOTA and for AMI 227 (7 mumol Fe/kg body weight). In the EPI sequence, a well-shaped curve was demonstrated for Gd-DOTA, and a plateau effect was noted for both concentrations of AMI 227. With the FLASH technique, dynamic susceptibility contrast imaging of rat brain can be performed with very low concentrations of AMI 227 compared with the Gd-DOTA concentration (0.2 mmol Gd/kg body weight) used in clinical practice. This could be of interest in perfusion imaging, because it may allow for first-pass susceptibility imaging after administration of a small volume in a narrow bolus.

Noninvasive measurements of infarct size after thrombolysis with a necrosis-avid MRI contrast agent

BACKGROUND

Gadophrin-2 is a new MRI contrast agent with high affinity for necrotic myocardium. The aim of the study was to evaluate whether noninvasive measurements of infarct size after thrombolysis are possible with gadophrin-2-enhanced MRI.

METHODS AND RESULTS

Coronary artery thrombosis was induced in 3 groups of dogs by the copper-coil technique. Thrombolytic therapy together with aspirin and heparin was initiated after 90 minutes of occlusion. One day (group A), 2 days (group B), or 6 days (group C) after infarction, gadophrin-2 was injected intravenously (50 micromol. kg-1). In vivo T1-weighted segmented turbo-FLASH, in vivo T2-weighted segmented half-Fourier turbo spin echo (HASTE), and T1- and T2-weighted spin-echo MRI of the excised heart were performed 24 hours after gadophrin-2 injection. Regions of strong enhancement were observed on T1-weighted images. Planimetry of short-axis MR images and of corresponding triphenyltetrazolium chloride (TTC)-stained left ventricular (LV) slices showed a close correlation between the enhanced areas and TTC-negative areas for both in vivo (r2=0.98, P<0.0001; mean difference, 0.9+/-2.0% [SD] of the LV volume [LVV]) and postmortem (r2=0.99, P<0.0001; mean difference, 0.9+/-1.4% of LVV) measurements. T2-weighted images overestimated the infarct size by 8.1+/-5.4% of LVV. The mean infarct size was 10.8+/-11.6% of LVV (group A), 22.4+/-11.7% (group B), and 5.1+/-9.3% (group C).

CONCLUSIONS

In this animal model, in vivo gadophrin-2-enhanced MRI could precisely determine infarct size after thrombolytic therapy. This technique may be very useful for the noninvasive evaluation of infarct size after reperfusion for AMI.

Developmental and regional-specific expression of FLRFamide peptides in the tobacco hornworm, Manduca sexta, suggests functions at ecdysis

The developmental profile of a family of three FLRFamide (Phe-Leu-Arg-Phe-NH2) peptides in the tobacco hornworm, Manduca sexta, revealed regional-specific expression patterns within the segmental ganglia. Levels of the three peptides-F7G (GNSFLRF-amide), F7D (DPSFLRFamide), and F10 (pEDVVHS-FLRFamide)-were always higher in the thoracic than abdominal ganglia. The predominant peptide also differed regionally, with F7G being highest in the thoracic ganglia and F7G and F100 being equivalent in the abdominal ganglia. Furthermore, we found regional-specific transient declines in ganglion peptide levels temporally correlated to ecdysis. Thoracic ganglion peptide levels declined at each molt, while abdominal ganglion levels declined over a period of 2 days after ecdysis. The decline in central levels was accompanied by an increase in levels in peripheral neurohemal sites, the transverse nerves (TNs). These observations suggest peptides were released from neurosecretory cells (NSCs) at ecdysis. Distinct sets of thoracic and abdominal NSCs and their processes in peripheral neurohemal sites were immunoreactive, supporting the biochemical data. These results also suggest the regional differences may arise from cellular-specific expression patterns for this family of peptides. In addition, fine immunoreactive processes were observed traveling between TNs and skeletal muscles, suggestive of myotropic actions. We propose that the release of different M. sexta FLRFamides from regionally distinct NSCs leads to a coordinated modulation of skeletal and visceral muscles that facilitate ecdysis.

[Retinal detachment after intraocular lens implantation]

OBJECTIVE

To study the specificity of retinal detachment after intraocular lens implantation.

METHODS

The specialty of this type of retinal detachment through the clinical observation of 44 eyes of 42 cases from 1991 to 1996 was analyzed.

RESULTS

The retinal detachment after intraocular lens implantation is more severe than others. It is more difficult to find a hole or holes because posterior capsular opacification and the implanted intraocular lens interfere with the careful search. The retinal detachment may develop into a complicated one. Its cure rate was 80.0% in the immediate postoperative period.

CONCLUSION

The retinal injury during intraocular lens implantation should be avoided. As the retinal detachment occurs after the implantation, a more careful search and a earlier scleral buckling or/and vitrectomy should be done.

[Study on pharmacological actions of pingxiaozhitong pill]

Pingxiaozhitong pill was administered ig. once daily for 7 successive days at dosages (4,2,2 g/kg). It was shown markelly suppressive effects on solid sarcoma 180 (S180) and Ehrlich aseites carcinoma (EAC) and synergism effect on cytoxan inhibiting S180 in mice. It had significant analgesic effect. 4,2 g/kg pingxiaozhitong pill enhanced effects on phagocysis of monocyte macrophage and value of hemagglutinin in serum in mice.

Identification of two new hydrophobic residues on basic fibroblast growth factor important for fibroblast growth factor receptor binding

Basic fibroblast growth factor (bFGF) is implicated in the pathogenesis of several types of vascular and connective diseases. A key step in the discovery of bFGF receptor antagonists to mitigate these actions is to define the functional epitopes required for receptor binding of the growth factor. Using structure-based site-directed mutagenesis, two critical areas on the bFGF surface for the high affinity receptor binding have already been identified [Springer, B.A., Pantoliano, M.W., Barberal, F.A., Gunyuzlu, P.L., Thompson, L.D., Herblin, W.F., Rosenfeld, S.A. and Book, G.W. (1994) J. Biol. Chem., 269, 26879-26884; Zhu, H.Y., Ramnarayan, K., Anchin, J., Miao, Y., Sereno, A., Millman, L., Zheng, J., Balaji, V.N. and Wolff, M.E. (1995) J. Biol. Chem., 270, 21869-21874; Zhu, H.Y., Anchin, J., Ramnarayan, K., Zheng, J., Kawai, T., Mong, S. and Wolff, M.E. (1997) Protein Engng, 10, 417-421]. According to these studies, one receptor binding site includes two polar residues Glu96 and Asn104 on bFGF whereas the other includes four hydrophobic residues Tyr24, Tyr103, Leu140 and Met142. Using a protein modelling technique, we report here the identification of a new hydrophobic patch on bFGF which includes residues Tyr73, Val88 and Phe93. The role of this area on receptor binding affinity was evaluated by mutating each of these residues individually and determining the mutated protein's (mutein's) receptor binding affinity. In addition, we examined the role of two other hydrophobic residues, Phe30 and Leu138, on bFGF for high-affinity receptor binding. These two residues are the neighbors of the hydrophobic residues Tyr24 and Tyr103, respectively. Replacement of Val88 and Phe93 with alanine reduced the receptor binding affinity about 10- and 80-fold, respectively, compared with wild-type bFGF. In contrast, substitution of Phe30 and Leu138 with alanine has no effect on the receptor binding affinities. We conclude that the newly identified hydrophobic residues, Val88 and Phe93, are crucial for the receptor binding. The present data, together with the previous identification of four hydrophobic residues (Tyr24, Tyr103, Leu140 and Met142), suggests that there are two hydrophobic receptor binding sites on the bFGF surface. Our findings can be employed in the discovery and design of potent bFGF antagonists using computational methods.

[Treatment of deep anterior overbite by using the fixed appliances in conjunction with a small bite plate]

OBJECTIVE

This study was to investigate the effective method in the reduction of deep anterior overbite.

METHODS

Twenty-nine cases of three-degree deep anterior overbite were treated by using the fixed appliances in conjunction with a small bite plate.

RESULTS

It was showed that this method was significantly quicker to reduce deep overbite of anterior teeth (2.04 +/- 0.78 mm per month) and shorter to require the time of treatment (3.94 +/- 1.55 months) than that by using the single fixed appliances (P < 0.001), and there was no significant difference between the adults and juveniles. These findings suggest that it was effective for both of adult and juvenile patients.

CONCLUSION

As the destruction of molar tubes, wire and bracket bonding failure caused by bite were less happened, it was effective to treat complicated cases of deep overbite with a shorter occlusogingival distance, posterior cross-bite and not enough alveolar highness of posterior teeth who could be difficult to treat by a routine method.

[Protective effects of folium Ginkgo extract on experimental cerebral ischemia of mice]

Folium Ginkgo extract(EGb761) has been proved able to significantly prolong the survival time of mice suffering from cerebral ischemia induced by occluding bilateral common carotids, and reduce the inhibition of cerebral GSH-Px and Na(+)-K(+)-ATPase activities during reperfusion processes of these mice. Pretreatment with EGb761 also helps alleviate the subcellular damages in hippocampus of cerebral ischemic mice.

[Experimental study on the role of the pedicle of the subdermal vascular network skin flap]

OBJECTIVE

The experiment was to investigate the role of the pedicle of the subdermal vascular network skin flap.

METHODS

Ten healthy white pigs, weighting from 20 to 25 kg were used. The subdermal vascular network skin flap and the traditional skin flap were designed and created on each side of the animal's flank. The traditional skin flap on the contralateral side of the flank was used as control. Flap survival was studied by gross observation and ECT examination of isotope distribution.

RESULTS

There were significant differences between the two groups in mean survival length and area (P < 0.05). In both groups the radioactive isotope gathering is restricted proximally with a ratio of length to width of (1-1.5):1.

CONCLUSION

The presence of the pedicle of the subdermal vascular network skin flap makes no difference compared the traditional skin flap.

Magnetic resonance imaging-histomorphologic correlation studies on paramagnetic metalloporphyrins in rat models of necrosis

RATIONALE AND OBJECTIVES

The authors intended to confirm previous findings that paramagnetic porphyrins are avid only for intratumoral nonviable tissues, but not for viable tumor cells, and to test the hypothesis that necrosis, regardless of location and origin, can be visualized by metalloporphyrin enhanced magnetic resonance imaging (MRI).

METHODS

Intravenous administrations of gadolinium mesoporphyrin (Gd-MP), manganese tetraphenylporphyrin (Mn-TPP), manganese methylpyrroporphyrin-gadopentetate dimeglumine complex (Mn-MPP-Gd) and manganese tetra(4-sulfonatophenyl)porphyrin (MnTPPS4) at 0.05 mmol/kg were compared with those of gadopentetate dimeglumine (Gd-DTPA) at 0.1 mmol/kg in 38 rats with cholestatic liver necrosis, alcohol- and laser-induced coagulation necrosis in liver, and skeletal muscle, reperfused hepatic infarction, and segmental renal infarction. T1-weighted spin echo MRI (TR/TE = 300/15 mseconds) was acquired before and as long as 48 hours after injection, matched with histologic findings, and correlated with Gd/ Mn tissue content measurements.

RESULTS

Both Gd-DTPA and the four metalloporphyrins initially caused a similar nonspecific negative contrast enhancement in the necrosis. However, a strong and persisting positive enhancement (necrosis-to-normal contrast ratio ranging from 1.5 to 2.0) developed only with metalloporphyrins in all types of necrosis. In liver and kidney, Gd and Mn concentrations at 24 hours were comparable in necrotic and normal tissues. In muscle, the concentrations were more than eight times higher in necrotic than in normal tissue.

CONCLUSIONS

The implied affinity of metalloporphyrins for necrosis with presumably increased relaxivity suggests a possible mode of targetability for MRI contrast media that may elicit novel applications.

[Study on the degradation kinetics of spiramycin in acid and alkaline solutions]

Physical and chemical characteristics of spiramycin (SPM) were reviewed in this paper. The degradation rule and kinetics of SPM in acid and alkaline solutions were studied, and the kinetic parameters were calculated. The experimental results showed that the stable range of SPM in water is at pH 4.0~10.0 Degradation occurred seriously at pH<4.0 and pH> 10.0, especially at pH< 2.8 and pH> 12.8. For this reason, the yield of SPM is greatly affected. The solubility in water was also studied by using reference data. The thermodynamical parameters were calculated. The results showed that the solution of SPM in water is exothermic. The solubility decreases as temperature rises.

[Effects of SAD on cytogenetics of mouse embryonic cells and its embryo development]

We report here that SAD may not only suppress transcription activity of rRNA genes, but also increase SCE frequency of mouse embryonic cells, leading to bloching of the embryo development and fetal death, and finally significant decrease of birth percentage of the new born offsprings. Ata concentration of SAD in 10(-5)mol/L, the transcription activity of rRNA genes was decreased to 15% of the normal level, and the SCE frequency was increased doubly, leading to that the birth percentage was decreased to 50% of normal one. When SAD concentration of 10(-3)mol/L was used the transcription activity of rRNA genes was completely suppressed and SCE frequency was increased to as 4.8 times high as normal, leading to that the birth percentage dropped to 4% from 100%. Our results indicates that both the cytogenetic effects and the inhibition of the embryonic cells are directly proportional to the SAD concentration used. The relationship between the change of both the rRNA gene transcription and SCE frequency and the degree of embryo development are also discussed preliminarily.

Ex vivo experiment on radiofrequency liver ablation with saline infusion through a screw-tip cannulated electrode

PURPOSE

To investigate whether radiofrequency (RF) therapy with hypertonic saline infusion through a hollow screw-tip electrode can cause a lesion size suitable for liver tumor ablation.

MATERIALS AND METHODS

RF tissue ablation of 180 sites was performed by using a hollow screw-tip electrode in 40 freshly excised swine livers. Under both power and temperature control modes, the ablation effects with and without various regimes of 5% hypertonic saline (1 ml/min) prior to and/or during the procedure were compared by measuring the size of lesions at dissection and confirmed by T1 and T2 weighted magnetic resonance (MR) imaging.

RESULTS

The maximal lesion diameter of 5.5 cm was reached at 30 W with saline infusion 1 min prior to and during 12 min of ablation. The smaller sizes (P < 0.01) between 0.3 and 2.5 cm in diameter were met with noninfusion or preinfusion-only groups. The RF ablation lesions appeared as hyper- and hypointense areas on T1 and T2 MR images, respectively.

CONCLUSIONS

RF ablation in combination with present hollow screw-tip electrode and saline infusion allows for necrotic development of suitable size for liver tumor ablation. Such ablated lesions can be visualized with MR imaging.

The orlA gene from Aspergillus nidulans encodes a trehalose-6-phosphate phosphatase necessary for normal growth and chitin synthesis at elevated temperatures

A cosmid carrying the orlA gene from Aspergillus nidulans was identified by complementation of an orlA1 mutant strain with DNA from the pKBY2 cosmid library. An orlA1 complementing fragment from the cosmid was sequenced. orlA encodes a predicted polypeptide of 227 amino acids (26360 Da) that is homologous to a 211-amino-acid domain from the polypeptide encoded by the Saccharomyces cerevisiae TPS2 gene and to almost the entire Escherichia coli otsB-encoded polypeptide. TPS2 and otsB each specify a trehalose-6-phosphate phosphatase, an enzyme that is necessary for trehalose synthesis. orlA disruptants accumulate trehalose-6-phosphate and have reduced trehalose-6-phosphatate phosphatase levels, indicating that the gene encodes a trehalose-6-phosphatate phosphatase. Disruptants have a nearly-wild-type morphology at 32 degrees C. When germinated at 42 degrees C, the conidia and hyphae from disruptants are chitin deficient, swell excessively, and lyse. The lysis is almost completely remedied by osmotic stabilizers and is partially remedied by N-acetylglucosamine (GlcNAc). The activity of glutamine:fructose-6-phosphate amido-transferase (GFAT), the first enzyme unique to aminosugar synthesis, is reduced and is labile in orlA disruption strains. The findings are consistent with the hypothesis that trehalose-6-phosphate reduces the temperature stability of GFAT and other enzymes of chitin metabolism at elevated temperatures. The results extend to filamentous organisms the observation that mutations in fungal trehalose synthesis are highly pleiotropic and affect aspects of carbohydrate metabolism that are not directly related to trehalose synthesis.

Comments on "Principal component extraction using recursive least squares learning"

In the above paper, (Bannour and Azimi-Sanjadi, 1995) we point out and correct flaws in the proofs of the orthonormal property of the optimal weight vectors of a two-layer linear auto-associative network used for sequentially extracting the principal components of a stationary vector stochastic process.