[Isotope tracer combined with trichloroacetic acid precipitation method for determination of nerve growth factor concentration in mouse plasma]

OBJECTIVE

To establish the radioisotope (125I) tracer method combined with trichloroacetic acid (TCA) precipitation for the determination of nerve growth factor (NGF) in mouse plasma.

METHODS

Radioisotope tracer labelling method combined with TCA precipitation was used to determine NGF in mouse plasma.

RESULTS

The detection limit of the method for NGF in plasma was 2.0 ng/ml. The intra-assay cv (CV) and the inter-assay CV were all less than 10%. The assay linearity was determined over the range of 12.5-400 ng/ml in plasma and the correlation coefficient was 0.9990. The average recovery of the method for NGF was 95.21%.

CONCLUSIONS

The radioisotope tracer method combined with TCA precipitation is stable, sensitive and reliable. It is suitable for the determination of NGF concentration in mouse plasma.

[Embryonic motoneurons transplanted into denervated skeletal muscles]

OBJECTIVE

To observe the living situation of homografting embryonic motoneurons in denervated skeletal muscles.

METHODS

We transplanted dissociated ventral spinal cord cells from 12 embryonic days rats prelabeled with 5-bromo-2-deoxyuridine(Brdur) into denervated skeletal muscles of adult rats. The denervated skeletal muscles were collected at 9 and 22 weeks respectively, and Nissl, acetylcholinesterases immunocytochemistry and ATPase staining were used to show the transplanted embryonic motoneurons and the morphography of muscle fibers.

RESULTS

Transplanted embryonic motoneurons could survive, extend out long axons, and form neuromuscular junctions with muscle fibers. Type grouping fibers with bigger transverse area were also observed in the experimental group. Muscle fibers were much smaller and did not form fiber type grouping in the control group.

CONCLUSION

Homografting embryonic motoneurons could survive well and reinnervate the denervated skeletal muscles.

[Lung autotransplantation technique in the treatment of stage III bronchogenic carcinoma]

OBJECTIVE

To perform a double sleeve right upper and middle bilobectomy with transposing the inferior pulmonary vein to the superior one stump in a lung cancer patient.

METHOD

The "cut-down" lobe was immersed in heparin solution in vitro for 15 minutes. It took 15, 14 and 10 minutes to finish the anastomosis of pulmonary vein, bronchus, and artery. The pulmonary artery was blocked for 3 hours. Postoperatively, the patient underwent ventilation for 6 hours.

RESULT

In the 5th day after operation, re-implanted lung inflated well, the chest tube was retreated, and the patient can walk around. The reconstruction of pulmonary vessels and airway was done by spiral CT, which demonstrated no stenoses of bronchi and the pulmonary blood perfused and returned very well 3 weeks after operation. Follow-up more than 6 months showed the patient had a good quality of life and resumed his work.

CONCLUSION

It is indicated to apply the technique of lung autotransplantation for operation on the central bronchogenic carcinoma when the main bronchus or pulmonary artery involved by tumor is too long to perform the anastomosis in the double sleeve bilobectomy.

[Reliability design and analysis of man-machine performance of display and illumination system in cockpit]

This paper analysed and discussed the basic reliability of display and illumination system in which Chinese characters displayed on LCD were read and the colours were identified, and instruments in different visual views and the instruments of differential display models were read. The colour rendering of the light source was also evaluated. Basic reliability may be chosen as 0.9995.

Melanopsin: An opsin in melanophores, brain, and eye

We have identified an opsin, melanopsin, in photosensitive dermal melanophores of Xenopus laevis. Its deduced amino acid sequence shares greatest homology with cephalopod opsins. The predicted secondary structure of melanopsin indicates the presence of a long cytoplasmic tail with multiple putative phosphorylation sites, suggesting that this opsin's function may be finely regulated. Melanopsin mRNA is expressed in hypothalamic sites thought to contain deep brain photoreceptors and in the iris, a structure known to be directly photosensitive in amphibians. Melanopsin message is also localized in retinal cells residing in the outermost lamina of the inner nuclear layer where horizontal cells are typically found. Its expression in retinal and nonretinal tissues suggests a role in vision and nonvisual photoreceptive tasks, such as photic control of skin pigmentation, pupillary aperture, and circadian and photoperiodic physiology.

The observation of transplanted embryonic motoneurons in the denervated muscles of adult rats

OBJECTIVE

To observe the survival of embryonic motoneurons after they were transplanted into the denervated skeletal muscles and to find a new method to retard the atrophy of denervated muscles.

METHODS

Dissociated embryonic motoneurons prelabled with 5-bromo-2'-deoxyuridine (Brdur) on the embryonic days 12 were injected into the denervated gastrocnemius muscles of adult rats. Then gastrocnemius muscles were processed with Nissl staining, acetylcholinesterase staining and Brdur immunocytochemical staining to show the implanted motoneurons at 9 and 22 weeks post-transplantation. Myofibrillar ATPase staining was used to show the morphology of muscle fibers. The rats in experimental group were implanted with embryonic motoneurons in the predenervation muscles, while the rats in control group were injected with just culture medium without motoneurons.

RESULTS

Embryonic motoneurons survived, developed and extended long axons to form neuromuscular junctions with the denervated muscles. The differentiation of muscle fibers and fiber type grouping occurred among bigger fibers in experimental group. The transverse area was smaller and there was no apparent fiber type grouping in control group.

CONCLUSIONS

Embryonic motoneurons can survive, develop and reinnervate denervated muscles after being transplanted into denervated muscles. It is worth further investigating on ameliorating the atrophy of denervated muscle.

[The effects of clenbuterol on intramuscular collagen metabolism in denervated muscle]

In order to explore the effects of clenbuterol on intramuscular collagen metabolism in denervated skeletal muscles, a randomized, double-masked and placebo-controlled group were studied. Seventy-one patients with complete function loss in muscularcutaneous nerve resulted from brachial plexus injury were administered clenbuterol or placebo 60 micrograms Bid for more than 3 months. Biopsies of the biceps brachia muscle were performed at the beginning and end of this study. The biopsied muscles were processed with anti-collagen I and IV immunohistochemical stains and image analysis as well. The result showed that the collagen proliferation of both type I and IV was much reducible in the clenbuterol-treated group than that of the placebo-treated group (P < 0.05). It was concluded that clenbuterol could inhibit partially the proliferation of intramuscular collagens in denervated skeletal muscle.

[Expression of hepatitis B virus S genes in Ad5 vector]

The hepatitis B virus (HBV) S gene, PreS2 + S genes and the late phase expression cassette (MTI) + HBV S genes were separately cloned into Ad5 vector downstream of E3 promoter (pAd5 deltaE3 provided by Wyeth Co.). The above constructed plasmids and Ad5 DNA EcoR I A fragment were cotransfected into 293 cells. The progeny adenoviruses named rAd5S, rAd5MS, rAd5S2S were harvested for analysis. The recombinants were isolated and analyzed by PCR, using two primers specific to the HBV S genes. The expressed products were detected by ELISA and RIA. The recombinant containing MIT + HBV S genes (rAd5MS) was identified to be ELISA positive, whereas the other two recombinants (rAd5S, rAd5S2S) were negative to ELISA, but positive to RIA. The results indicated that adenovirus E3 early promoter could express the inserted foreign genes, and MIT worked well in the E3 region of Ad5 and could increase the expression capacity of the recombinants. The conditions for foreign gene expression and genetic stability of the recombinant viruses were studied in detail. There was no wild Ad5 discovered during the cotransfection experiments. The present study provides some experiences for studying adenovirus recombination.

[Theoretical exploration of man-machine role distribution in long term manned space flight]

To explore the principle of man-machine role distribution in long duration manned space flight, the human tasks and factors affecting human performance capability were analyzed, and a man-machine functional allocation model based on stress-strength was put forward.

Betidamino acid scan of the GnRH antagonist acyline

Strong clinical evidence suggests that GnRH antagonists will replace GnRH agonists in a number of indications because of their ability to inhibit gonadotropin secretion as long as an adequate concentration of the analogue is present in the circulation whereas superagonists will take approximately 2 weeks to desensitize the gonadotrophs. Until recently, antagonists were either too weak and/or would release histamine. Azaline B {[Ac-D2Nal1,D4Cpa2,D3Pal3, 4Aph5(atz),D4Aph6(atz),ILys8,DAla10] GnRH} and long-acting members of the azaline family {Ac-D2Nal-D4Cpa-D3Pal-Ser-4Aph(X)-D4Aph(Y) -Leu-ILys-Pro-DAla-NH2}, however, appear to be promising drug candidates. Because these antagonists tend to form gels (due to the formation of beta-sheet structures) and, as a result, are not readily amenable to formulation for long-term delivery, we have investigated ways of increasing hydrophilicity while retaining high potency and lack of histamine releasing activity. Betidamino acids (a contraction of "beta" position and "amide") are N'-monoacylated (optionally, N'-monoacylated and N-mono- or N,N'-dialkylated) aminoglycine derivatives in which each N'-acyl/alkyl group may mimic naturally occurring amino acid side chains or introduce novel functionalities. We have used unresolved N alpha-Boc,N'alpha-Fmoc-aminoglycine, and N alpha-Boc,N'alpha-(CH3)Fmoc-aminoglycine as templates for the introduction of betidamino acids in acyline (Ac-D2Nal-D4Cpa-D3Pal-Ser-4Aph(Ac)-D4Aph(A c)-Leu-Ilys-Pro-DAla-NH2), a long acting member of the azaline B family, to test biocompatibility of these betide derivatives. Diastereomeric peptides could be separated using RP-HPLC in most cases. Biological results obtained in vitro (binding affinity to rat pituitary gland membranes) and in vivo (rat antiovulatory assay, AOA) indicate in most cases small differences in relative potencies (< 5-fold) between the D- and L-nonalkylated betidamino acid-containing acylines. Importantly, most betide diastereomers have high affinity for the GnRH receptor and were equipotent with acyline in the AOA. Greater differences in affinity and potency between diastereomers were observed after introduction of a methyl group on the side chain nitrogen ("beta" position) of the same analogues, with one of the diastereomer having an affinity and a potency in the AOA equivalent to that of acyline. These results suggest that chirality at the alpha-carbon coupled to side chain orientation is important for receptor recognition. The duration of action of some of the most potent analogues was also determined in the castrated male rat in order to measure the extent (efficacy and duration of action) of inhibition of luteinizing hormone release. Data suggest that introduction of a betidamino acid results in reduction of duration of action. Also, introduction of betidamino acids results in peptides with increased hydrophilicity (as determined by elution times on C18 silicas at pH 7.3) compared to that of the parent compound. N'-Methyl substitution results in parallel increase in retention times on C18 silicas as expected.

Proposed mechanism for the stabilization of nuclear receptor DNA binding via protein dimerization

Hepatocyte nuclear factor 4 (HNF-4) defines a new subgroup of nuclear receptors that exist in solution and bind DNA exclusively as homodimers. We recently showed that the putative ligand binding domain (LBD) of HNF-4 is responsible for dimerization in solution and prevents heterodimerization with other receptors. In this report, the role of the LBD in DNA binding by HNF-4 is further investigated by using electrophoretic mobility shift analysis. A comparison of constructs containing either the DNA binding domain (DBD) alone or the DBD plus the LBD of HNF-4 showed that dimerization via the DBD was sufficient to provide nearly the full DNA binding affinity of the full-length HNF-4. In contrast, dimerization via the DBD was not sufficient to produce a stable protein-DNA complex, whereas dimerization via the LBD increased the half-life of the complex by at least 100-fold. Circular permutation analysis showed that full-length HNF-4 bent DNA by approximately 80 degrees while the DBD bent DNA by only 24 degrees. Nonetheless, analysis of other constructs indicated that the increase in stability afforded by the LBD could be explained only partially by an increased ability to bend DNA. Coimmunoprecipitation studies, on the other hand, showed that dimerization via the LBD produced a protein-protein complex that was much more stable than the corresponding protein-DNA complex. These results led us to propose a model in which dimerization via the LBD stabilizes the receptor on DNA by converting an energetically favorable two-step dissociation event into an energetically unfavorable single-step event. Implications of this one-step model for other nuclear receptors are discussed.

PCR detection of human papillomavirus: comparison between MY09/MY11 and GP5+/GP6+ primer systems

Human papillomavirus (HPV) is an etiologic agent of cervical cancer and is the most common sexually transmitted disease in women. PCR amplification of HPV genomes is the most sensitive method for the detection of cervicovaginal HPV. We have compared the two most commonly used PCR primer sets, MY09/MY11 (MY-PCR) and GP5+/GP6+ (GP+-PCR), for the detection of HPV DNA in cervicovaginal lavage samples from 208 women. Oligonucleotide probes for 39 different HPV types were used. Both primer sets amplified a wide spectrum of HPV genotypes and detected similar overall prevalences of 45% (94 of 208) and 43% (89 of 208), respectively. The MY-PCR system detected 27 of 30 (90%) samples with multiple HPV types, whereas the GP+-PCR system detected 14 of 30 (47%) samples with multiple HPV types. Differences in the detection of HPV types 35, 53, and 61 were noted between the two primer systems. Serial dilution of plasmid templates indicated a 3-log decrease in the amplification of HPV type 35 by MY-PCR and HPV types 53 and 61 by GP+-PCR. These results indicate that although the MY-PCR and GP+-PCR identified nearly equivalent prevalences of HPV in a set of clinical samples, differences in the detection of specific types and infections with multiple types were found. Differences in the sensitivities and characteristics of the PCR systems for the detection of HPV within clinical samples should be considered when comparing data between studies and/or in designing new studies or clinical trials.

Serine/threonine phosphorylation of orphan receptor hepatocyte nuclear factor 4

We showed previously that hepatocyte nuclear factor 4 (HNF-4) defines a new subclass, Group IV, of nuclear receptors. In order to determine whether members of this subclass are phosphorylated, HNF-4 was overexpressed to high levels in insect cells using a baculovirus expression system. The baculovirus-expressed HNF-4 (HNF4.BV) was characterized and compared to HNF-4 overexpressed in transiently transfected mammalian (COS-7) cells (HNF4.COS). The results indicate that both HNF4.BV and HNF4.COS are phosphorylated although HNF4.BV was hypophosphorylated relative to HNF4.COS. Phosphoamino acid analysis showed that HNF-4 is phosphorylated mainly on serine and to a lesser extent on threonine residues. Phosphopeptide mapping revealed 13 phosphopeptides for HNF4.COS, only 9 of which were present in the HNF4.BV sample. DNA-binding studies also showed that HNF4.BV binds DNA with a lower specificity and affinity, as measured by the equilibrium dissociation constant (Kd), than does HNF4.COS. Partial proteolytic digestion experiments also revealed that HNF4.BV and HNF4.COS adopt somewhat different three-dimensional conformations. Since glycosylation of HNF4.BV was ruled out by a number of methods and since HNF-4 expressed in bacteria exhibited an even lower DNA-binding affinity than HNF4.BV, we propose that serine/theronine phosphorylation may play a role in the DNA-binding activity of HNF-4 and, therefore, possibly of other Group IV receptors as well.

The DNA binding domain of hepatocyte nuclear factor 4 mediates cooperative, specific binding to DNA and heterodimerization with the retinoid X receptor alpha

We recently showed that hepatocyte nuclear factor 4 (HNF-4) defines a unique subclass of nuclear receptors that exist in solution and bind DNA elements as homodimers (Jiang, G., Nepomuceno, L., Hopkins, K., and Sladek, F. M. (1995) Mol. Cell. Biol. 15, 5131-5143). In this study, we show that the dimerization domains of HNF-4 map to both the DNA binding and the ligand binding domain. Whereas the latter is critical for dimerization in solution, the DNA binding domain mediates cooperative, specific binding to direct repeats of AGGTCA separated by one or two nucleotides. Whereas amino acid residues 117-125 (the T-box/third helix region) are insufficient for cooperative homodimerization and high affinity DNA binding, residues 126-142 (encompassing the A-box region) are required. Finally, in contrast to the full-length receptor, the DNA binding domain of HNF-4 is capable of heterodimerizing with that of the retinoid X receptor alpha but not with that of other receptors. These results indicate that the HNF-4 DNA binding domain is distinct from that of other receptors and that the determinants that prevent HNF-4 from heterodimerizing with RXR lie outside the DNA binding domain, presumably in the ligand binding domain.

[Measurements of serum and subretinal fluid before and after surgery of retinal detachment]

OBJECTIVES

To investigate the relationships between proliferative vitreoretinopathy (PVR) formation and the levels of human epidermal growth factor (h-EGF) and tumor necrosis factor (TNF) in serum and subretinal fluid (SRF) before and after surgery of retinal detachment with PVR.

METHODS

Serum and SRF samples of 51 patients with retinal detachment and PVR were collected, and their h-EGF and TNF levels were measured by radioimmunoassays.

RESULTS

In comparison with the control group, the levels of h-EGF and TNF in serum and SRF in retinal detachment with PVR group were higher but not statistically significant (P > 0.05). Their levels in the serum were not related to the severity of the disease, while their levels in SRF increased significantly with the increase of the severity of the disease, and these two factors were positively correlated (P < 0.05). 5 days after the surgery of retinal detachment, the h-EGF and TNF levels in serum increased significantly (P < 0.01) and the levels decreased within 30 days but not to normal.

CONCLUSIONS

The h-EGF and TNF in SRF might have a synergic action and affect the formation and development of PVR. The h-EGF and TNF in serum take part in the repair of the operative trauma and inflammatory reaction. However, their high levels could interfere with the effect of operation.

Room-temperature green upconversion fluorescence of an Er(3+)-doped laser liquid

Room-temperature green upconversion fluorescence of an Er(3+)-doped POCl(3)-SnCl(4) solution is achieved when the solution is pumped with an 800-nm GaAs laser diode. The upconversion emission at 550 nm is determined to be the result of a two-step absorption process. Numerical analysis reveals that laser systems that employ this erbium-doped laser liquid should be realizable with threshold pump powers as low as 45 mW.

[A genetic epidemiological study on lung cancer]

Segregation ratio, heritability and relative risk of genetic susceptibility were estimated for 355 families of lung cancer in matched pair with genetic epidemiological methods. Results showed that segregation ratio for lung cancer was 0.09-0.12 (95% confidence interval, CI) and heritability of lung cancer was (40.58 +/- 4.01)% and (27.58 +/- 4.76)% for smokers and non-smokers, respectively. Relative risks of genetic susceptibility to lung cancer were 4.73 (95% CI 3.90-5.74) and 2.61 (95% CI 2.18-3.13) in their first and second degree relatives, respectively, after adjustment of smoking with a logistic regression model. It was also found that there was an interaction between smoking habit and genetic background of lung cancer. Thus, it is believed that genetic background is one of the multifactorial causes in lung cancer.

Betidamino acids: versatile and constrained scaffolds for drug discovery

Betidamino acids (a contraction of "beta" position and "amide") are N'-monoacylated (optionally, N'-monoacylated and N-mono- or N,N'-dialkylated) aminoglycine derivatives in which each N'acyl/alkyl group may mimic naturally occurring amino acid side chains or introduce novel functionalities. Betidamino acids are most conveniently generated on solid supports used for the synthesis of peptides by selective acylation of one of the two amino functions of orthogonally protected aminoglycine(s) to generate the side chain either prior to or after the elongation of the main chain. We have used unresolved Nalpha-tert-butyloxycarbonyl-N'alpha-fluorenylmethoxycarbonyl++ + aminoglycine, and Nalpha-(Nalpha-methyl)-tert-butyloxycarbonyl-N'alpha-fluo renylmethoxycarbonyl aminoglycine as the templates for the introduction of betidamino acids in Acyline [Ac-D2Nal-D4Cpa-D3Pal-Ser-4Aph(Ac)-D4Aph(A c)-Leu-Ilys-Pro-DAla-NH2, where 2Nal is 2-naphthylalanine, 4Cpa is 4-chlorophenylalanine, 3Pal is 3-pyridylalanine, Aph is 4-aminophenylalanine, and Ilys is Nepsilon-isopropyllysine], a potent gonadotropin-releasing hormone antagonist, in order to test biocompatibility of these derivatives. Diasteremneric peptides could be separated in most cases by reverse-phase HPLC. Biological results indicated small differences in relative potencies (<5-fold) between the D and L nonalkylated betidamino acid-containing Acyline derivatives. Importantly, most betide diastereomers were equipotent with Acyline. In an attempt to correlate structure and observed potency, Ramachandran-type plots were calculated for a series of betidamino acids and their methylated homologs. According to these calculations, betidamino acids have access to a more limited and distinct number of conformational states (including those associated with alpha-helices, beta-sheets, or turn structures), with deeper minima than those observed for natural amino acids.

[Assay of contents of lysozyme, SIgA, IgA and IgG in tongue coating]

The contents of lysozyme, SIgA, IgA, and IgG in 98 cases with pathological tongue coating and 30 cases of normal coating were analysed by using the thorough random analysis of variance. The results showed that the content of lysozyme in pathological coating was lower than that in normals significantly (P < 0.0001), while the contents of SIgA, IgG in pathological coating were higher than that of normals (P < 0.0001). It indicates that immune reaction is very active during the development of pathological tongue coating.

Molecular cloning and functional analysis of the promoter of the human squalene synthase gene

We have cloned and characterized the 5'-flanking region of the gene encoding human squalene synthase. We report here the promoter activity of successively 5'-truncated sections of a 1 kilobase of this region by fusing it to the coding region of a luciferase reporter gene. DNA segments of 200 base pairs (bp) 5' to the transcription start site, as determined by primer extension analysis, show a strong promoter effect on the expression of the luciferase chimeric gene and a high response to the presence of sterols when transiently transfected into the human hepatoma cell line HepG2 or to the hamster-derived CHO-K1 cells. An approximately 50-fold induction of luciferase activity, in the absence of sterols, was observed in transiently transfected HepG2 cells for fusion constructs containing sections of 200, 459, and 934 bp of the putative human squalene synthase promoter. Loss of promoter activity and response to sterols was localized to a 69-bp section located 131 nucleotides 5' to the transcription start site. Sequence analysis of this region showed that it contained a sterol regulatory element 1 (SRE-1) previously identified in other sterol regulated genes (Smith, J. R., Osborne, T. F., Brown, M. S., Goldstein, J. L., and Gil, G. (1988). J. Biol. Chem. 263, 18480-18487) and two potential NF-1 binding sites. Additional CCAAT box, SRE-1 element, and two Sp1 sites were identified 3' to this section. Sequences within this 69-bp DNA, including the SRE-1 cis-acting element, show strong binding to the purified nuclear transcription factor ADD1 (Tonzonoz, P., Kim, J. B., Graves, R. A., and Spiegelman B. M. (1993) Mol. Cell Biol. 13, 4753-4759) by mobility shift assay and footprinting analyses.

Exclusive homodimerization of the orphan receptor hepatocyte nuclear factor 4 defines a new subclass of nuclear receptors

Hepatocyte nuclear factor 4 (HNF-4), a highly conserved member of the steroid hormone receptor superfamily critical for development and liver-specific gene expression, is very similar to another superfamily member, retinoid X receptor alpha (RXR alpha), in overall amino acid sequence and DNA binding specificity. Since RXR alpha is known to heterodimerize with many other nuclear receptors, the formation of heterodimers between HNF-4 and RXR alpha was examined. With the electrophoretic mobility shift assay, coimmunoprecipitation, and transient transfection assays, it is shown that, unlike other nuclear receptors, HNF-4 does not form heterodimers with RXR alpha either in the presence or in the absence of DNA. We also show that in vitro-translated HNF-4 does not form heterodimeric complexes on DNA with a number of other receptors, including RXR beta, RXR gamma, retinoic acid receptor alpha, or thyroid hormone receptor alpha. To investigate the hypothesis that the lack of heterodimerization between HNF-4 and RXR alpha is due to a strong homodimerization activity of HNF-4, glycerol gradient sedimentation and kinetic analysis were used to show that HNF-4 is in fact a stable homodimer in solution. Finally, immunohistochemistry is used to show that the HNF-4 protein is found exclusively in the nuclei in both HepG2 cells, which express endogenous HNF-4, and transfected COS cells, which overexpress HNF-4. These findings lead us to propose that HNF-4 defines a new subclass of nuclear receptors which reside primarily in the nucleus and which bind DNA and regulate transcription as homodimers.