Enzymological characterization of the signal-transducing uridylyltransferase/uridylyl-removing enzyme (EC 2.7.7.59) of Escherichia coli and its interaction with the PII protein

The uridylyltransferase/uridylyl-removing enzyme (UTase/UR) of Escherichia coli plays an important role in the regulation of nitrogen assimilation by controlling the uridylylation state of the PII signal transduction protein (PII) in response to intracellular signals. The reversible uridylylation of PII indirectly controls the activity of PII receptors that regulate transcription from nitrogen-regulated promoters and the activity of glutamine synthetase. Here, we present a detailed analysis of the uridylyltransferase and uridylyl-removing activities and their regulation by the small molecule effectors ATP, 2-ketoglutarate, and glutamine. Several important features of enzyme mechanism and regulation were elucidated. Mg2+ appeared to be the physiologically relevant metal ion cofactor for both transferase and uridylyl-removing activities. The transferase reaction proceeded by an ordered bi-bi kinetic mechanism, with PII binding before UTP and pyrophosphate (PPi) released before PII-UMP. The uridylyl-removing reaction proceeded with rapid equilibrium binding of substrate and random release of products. Both reactions were activated by ATP and 2-ketoglutarate, which did so by binding only to PII and PII-UMP. The binding of these effectors to PII and PII-UMP was characterized. Glutamine inhibited the transferase reaction by inhibiting the chemistry step, while glutamine provided nonessential mixed-type activation of the uridylyl-removing activity, lowering the apparent Km and increasing kcat. Our data were consistent with the hypothesis that all effects of glutamine are due to the binding of central complexes at a single glutamine site. By comparing the effects of the activators with their reported in vivo concentrations, we conclude that in intact cells the uridylylation state of PII is regulated mainly by the glutamine concentration and is largely independent of the 2-ketoglutarate concentration. Our kinetic data were consistent with the hypothesis that both transferase and uridylyl-removal reactions occurred at a single active center on the enzyme.

The regulation of Escherichia coli glutamine synthetase revisited: role of 2-ketoglutarate in the regulation of glutamine synthetase adenylylation state

The regulation of Escherichia coli glutamine synthetase (GS) by reversible adenylylation has provided one of the classical paradigms for signal transduction by cyclic cascades. Yet, many mechanistic features of this regulation remain to be elucidated. We examined the regulation of GS adenylylation state in a reconstituted system containing GS, adenylyltransferase (ATase), the PII signal transduction protein that controls ATase, and the uridylyltransferase/uridylyl-removing enzyme (UTase/UR), which has a role in regulating PII. In this reconstituted bicyclic cascade system, the adenylylation state of GS was regulated reciprocally by the small molecule effectors 2-ketoglutarate and glutamine at physiological effector concentrations. By examination of the individual regulatory monocycles and comparison to the bicyclic system and existing data, we could deduce that the only sensors of 2-ketoglutarate were PII and PII-UMP. At physiological conditions, we observed that the main role of 2-ketoglutarate in bringing about the deadenylylation of GS was to inhibit GS adenylylation, and this was due to the allosteric regulation of PII activity. Glutamine acted as an allosteric regulator of both ATase and UTase/UR. We also compared the regulation of GS adenylylation state to the regulation of phosphorylation state of the transcription factor NRI (NtrC) in a reconstituted bicyclic system containing NRI, the bifunctional kinase/phosphatase NRII (NtrB), PII, and the UTase/UR. This comparison indicated that, at a fixed 2-ketoglutarate concentration, the regulation of GS adenylylation state by glutamine was sharper and occurred at a higher concentration than did the regulation of NRI phosphorylation. The possible biological implications of this regulatory arrangement are discussed.

Reconstitution of the signal-transduction bicyclic cascade responsible for the regulation of Ntr gene transcription in Escherichia coli

Nitrogen-regulation of gene transcription in Escherichia coli results from the regulation of the phosphorylation state of the enhancer-binding transcription factor NRI (NtrC). We examined the regulation of NRI phosphorylation in a reconstituted bicyclic cascade system containing four regulatory proteins: NRI, the signal-transducing uridylyltransferase/uridylyl-removing enzyme (UTase/UR), its substrate the signal transduction protein PII, and the kinase/phosphatase NRII (NtrB), which is a PII receptor that phosphorylates and dephosphorylates NRI. In this reconstituted system, the phosphorylation state of NRI was regulated reciprocally by the small molecule effectors glutamine, which prevented the accumulation of NRI-P, and 2-ketoglutarate, which caused accumulation of NRI-P. Regulation of the bicyclic system by glutamine was exclusively due to sensation and signal-transduction by the UTase/UR-PII monocycle, which was observed to function essentially as a glutamine-sensing apparatus. In contrast, regulation of NRI phosphorylation by 2-ketoglutarate, which binds to PII, was due to direct regulation of the NRII-PII interaction and the rate of NRI-P dephosphorylation. Thus, the PII protein transduces the glutamine signal to the NRII-NRI monocycle in the form of its uridylylation state and is also the receptor of the antagonistic 2-ketoglutarate signal, which blocks the activity of unmodified PII.

Endothelial cell death, angiogenesis, and microvascular function after castration in an androgen-dependent tumor: role of vascular endothelial growth factor

The sequence of events that leads to tumor vessel regression and the functional characteristics of these vessels during hormone-ablation therapy are not known. This is because of the lack of an appropriate animal model and monitoring technology. By using in vivo microscopy and in situ molecular analysis of the androgen-dependent Shionogi carcinoma grown in severe combined immunodeficient mice, we show that castration of these mice leads to tumor regression and a concomitant decrease in vascular endothelial growth factor (VEGF) expression. Androgen withdrawal is known to induce apoptosis in Shionogi tumor cells. Surprisingly, tumor endothelial cells begin to undergo apoptosis before neoplastic cells, and rarefaction of tumor vessels precedes the decrease in tumor size. The regressing vessels begin to exhibit normal phenotype, i.e., lower diameter, tortuosity, vascular permeability, and leukocyte adhesion. Two weeks after castration, a second wave of angiogenesis and tumor growth begins with a concomitant increase in VEGF expression. Because human tumors often relapse following hormone-ablation therapy, our data suggest that these patients may benefit from combined anti-VEGF therapy.

A randomized trial of the effect of ritonavir in maintaining quality of life in advanced HIV disease. Advanced HIV Disease Ritonavir Study Group

BACKGROUND

The aim of treatment for HIV disease is prolonging survival and improvement in health-related quality of life. Ritonavir is a potent, orally bioavailable HIV protease inhibitor with demonstrated impact on surrogate endpoints, AIDS-defining disease, and mortality.

OBJECTIVES

To evaluate the effect of ritonavir combined with reverse transcriptase inhibitor therapy on patient functioning and well-being.

METHODS

An international, multicenter randomized placebo-controlled clinical trial of ritonavir was conducted in HIV-infected patients with CD4 cell counts < or = 100 x 10(6)/l. A total of 1090 patients were randomized to ritonavir and continued treatment with as many as two nucleoside agents (n=543) or placebo and continued treatment with as many as two nucleoside agents (n=547). Health-related quality of life was measured at baseline and after 3 and 6 months of treatment using the Medical Outcomes Study HIV Health Survey (MOS-HIV) and HIV-related symptoms scale. MOS-HIV contains 10 subscales and two summary scores (physical health and mental health).

RESULTS

The two treatment groups were comparable on baseline CD4 cell counts, demographic characteristics, and MOS-HIV and HIV symptom subscale scores. After 3 months, statistically significant differences (P < 0.03) favoring the ritonavir-treated patients were seen on the physical health summary, mental health summary, and general health perceptions, social function, mental health, and energy/fatigue subscales. After 6 months of ritonavir therapy, significant differences were observed on physical health and mental health summary scores (P < 0.001), and on measures of general health perceptions, physical function, role function, social function, cognitive function, mental health, health distress, energy/fatigue, and overall ratings of quality of life (P < 0.01). Ritonavir-treated patients reported fewer fever symptoms and neurologic symptoms than the placebo group after 6 months of treatment (P < 0.005).

CONCLUSIONS

Ritonavir therapy, combined with other antiretroviral treatments, significantly contributes to maintenance of functioning and well-being over at least 6 months in patients with advanced HIV disease.

[Changes in distortion product otoacoustic emissions and hair cells after noise exposure in guinea pigs]

In order to observe the changes in distortion product otoacoustic emissions (DPOAE) and hair cells after noise exposure, sixteen healthy guinea pigs were used. The animals were divided into 3 groups. Group 1 was normal animals. Group 2 and 3 were animal right and 7 days after exposed to 115 dB SPL simulated submarine engine room noise for 4 hours, respectively. The DPOAE audiogram and I/O function were measured before and after exposure. The changes of hair cells were observed by light microscope and scanning electron microscope. The amplitudes of DPOAE disappeared right after noise exposure(P < 0.01) and recovered to normal at 7 days after exposure (P > 0.05). The light microscopy and scanning electron microscopy showed the stereocilia of the outer hair cells were disarrangement and some disappeared at 2,3,4 kHz regions of the cochlea. The results indicated that the normal outer cells can regulate and compensate the function of some damaged outer hair cells which result in a normal DPOAE in mild damaged cochlea.

Expression and regulation of hFIX minigene and cDNA driven by beta-casein gene in mouse mammary gland

Mammary gland specific expression vectors for human clotting factor IX (hFIX) and LacZ reporter gene driven by bovine beta-casein gene were constructed. Vectors were packaged by stearylamine (SA) liposome and were transferred to lactating mice via tail vein. Both hFIX and Lac2 gene could be expressed in the mammary gland of the treated mice. The highest production of hFIX protein was 80.28 ng per mL milk, and more than 85% of hFIX protein appeared to be gamma-carboxylation and biologically active. The results suggested that the 2.0 kb sequence of beta-casein gene including promoter, exon 1 was effective to drive hFIX gene expression in mammary gland and intron 1 of beta-casein gene had an effect on the tissue specific expression. The expression level in mouse milk injected with hFIX minigene vector containing hFIX endogenous intron 1 was increased by above 3 times of that injected with hFIX cDNA vector.

Membrane protein proteolysis assayed by fluorescence quenching: assay of O-sialoglycoprotein endopeptidase

The assay of the O-sialoglycoprotein endopeptidase of Pasteurella haemolytica has previously used the cleavage of 125I-labeled glycophorin A, measured by SDS-PAGE, autoradiography, gel-slicing, and scintillation counting. A new assay is based on the increased fluorescence which results from proteolytic cleavage of a fluorescence-quenched micellar substrate, 4,4-difluor-5,7-dimethyl-4-bora-3 alpha, 4 alpha-diaza-s-indacene-3-propionic acid conjugated to glycophorin A (BODIPY-FL-glycophorin A). Micellar association of glycophorin A molecules results in 97% fluorescence quenching despite a low molar ratio of BODIPY-FL-glycophorin A. Proteolysis of the membrane protein causes greatly enhanced fluorescence which is used for a rapid one-step proteolysis assay. Direct monitoring of proteolysis in microcuvettes, or routine assay in microtiter plates can be used. Reproducibility is higher than with the radiolabeled substrate and the K(m) values for the two substrates are similar. The assay is suitable for the O-sialoglycoprotein endopeptidase activity of chromatographically purified enzyme or unpurified bacterial culture supernatants and can be used to monitor inhibition of the O-sialoglycoprotein endopeptidase by neutralizing antibodies. The O-sialoglycoprotein endopeptidase assay employing BODIPY-FL-glycophorin A provides a rapid and nonradioactive method for the assay of this highly specific enzyme.

[Applied anatomy of the temporal and frontal regions in endoscopic temporal lifting]

OBJECTIVE

This anatomic study was carried out in a bid to decrease damage of the temporal branch of the face nerve in endoscopic temporal lifting.

METHODS

We dissected the frontal-temporal region and located the temporal branch on 36 sides of adult head specimens.

RESULTS

It was found that the temporal branch is deep to the temporoparietal fascia and frontal muscle. The temporal branch has one to four branches in general. The first one is 8.1 +/- 2.1 mm anterior to articular tubercle and 33.8 +/- 4.9 mm superior to the bony lateral canthus. The temporal branches locate below a line drawn from the articular tubercle to 40 mm above the bony lateral canthus.

CONCLUSION

It is suggested that the operation incisions in the temporal region be selected above this line.

Inner ear damage in guinea pigs exposed to stable and impulse noise

OBJECTIVE

To investigate the inner ear damage after exposure to stable noise, impulse noise and stable plus impulse noise in guinea pigs.

METHODS

Ninety-six healthy guinea pigs were divided into 3 equal groups. (1) Stable noise group: exposed to 110 dBA stable noise for 3 days, 4 hours per day. (2) Impulse noise group: exposed to 165 dBA simulated cannon fire impulse noise 10 times successively at an interval of 10 seconds. (3) stable plus impulse noise group: exposed to the same stable noise as that in the first group, then after a 2-hour rest, the animals were followed with impulse noise exposures as that in the second group. After those exposure, each of the 3 groups was further divided into 4 subgroups according to the time after the noise exposure, namely, the right after, 7 d, 14 d and 30 d groups. The evoked cortical potential responses to click and tone burst stimulation sound were examined. The surface preparation and celloidine embedded serial section of the cochlea were observed under a light microscope.

RESULTS

Both the stable and impulse noise could increase the hearing threshold and damage the inner ear hair cells. The damage in the first group was relatively slight, whereas in group 3 the damage was more severe than that in the other 2 groups.

CONCLUSION

For seamen who are working in heavy noise environment, corresponding measures should be taken to protect their ears from noise which induces hearing loss.

Diffusion, perfusion, and T2 magnetic resonance imaging of anti-intercellular adhesion molecule 1 antibody treatment of transient middle cerebral artery occlusion in rat

The effect of anti-intercellular adhesion molecule-1 (anti-ICAM-1) antibody treatment of transient (2 h) middle cerebral artery (MCA) occlusion in the rat was measured using diffusion (DWI)-, T2 (T2I)- and perfusion (PWI)-weighted magnetic resonance imaging. Rats were treated upon reperfusion with an anti-ICAM-1 monoclonal antibody (n=11) or a control antibody (n=7). DWI, T2I and PWI were performed before, during, and after induction of focal cerebral ischemia from 1 h to 7 days. In both groups, the apparent diffusion coefficient of water (ADCw) and cerebral blood flow (CBF) values in the ischemic region significantly declined from the preischemic ADCw values (p<0. 05). The post ischemic increase in T2 of the control group was significantly higher at 48 h than in the anti-ICAM-1 treated group (p<0.05). CBF was not significantly different between the two groups. The temporal profiles of MRI cluster analysis, which combines ADCw and T2 maps into a single image, was significantly different between groups. These data suggest that the neuroprotective effect of anti-ICAM-1 antibody treatment is reflected in reductions of T2 and lesion growth during reperfusion and may not be associated with increased cerebral perfusion.

Mutant human presenilin 1 protects presenilin 1 null mouse against embryonic lethality and elevates Abeta1-42/43 expression

Mutations in presenilin 1 (PS1) are linked to early onset of familial Alzheimer's disease (FAD) and are shown to foster production of Abeta1-42/43 in FAD patients and transgenic mice. PS1 null mice are embryonic lethal and exhibit axial skeleton malformation and CNS defects. We show that transgenic mouse lines expressing either the wild-type human PS1 protein or human PS1 with the A246E FAD mutation can rescue the PS1 knockout mouse from embryonic lethality to similar degrees, indicating that the mutation does not lead to loss of PS1 function during development. Furthermore, a 50% reduction of PS1 activity in PS1(+/-) mice does not lead to Abeta1-42/43 increase, whereas expression of human mutant PS1 on murine PS1 null background is sufficient to elevate Abeta1-42/43, supporting a gain-of-function activity as the result of the PS1 mutation.

Structure/function analysis of the PII signal transduction protein of Escherichia coli: genetic separation of interactions with protein receptors

The PII protein, encoded by glnB, is known to interact with three bifunctional signal transducing enzymes (uridylyltransferase/uridylyl-removing enzyme, adenylyltransferase, and the kinase/phosphatase nitrogen regulator II [NRII or NtrB]) and three small-molecule effectors, glutamate, 2-ketoglutarate, and ATP. We constructed 15 conservative alterations of PII by site-specific mutagenesis of glnB and also isolated three random glnB mutants affecting nitrogen regulation. The abilities of the 18 altered PII proteins to interact with the PII receptors and the small-molecule effectors 2-ketoglutarate and ATP were examined by using purified components. Results with certain mutants suggested that the specificity for the various protein receptors was altered; other mutations affected the interaction with all three receptors and the small-molecule effectors to various extents. The apex of the large solvent-exposed T loop of the PII protein (P. D. Carr, E. Cheah, P. M. Suffolk, S. G. Vasudevan, N. E. Dixon, and D. L. Ollis, Acta Crytallogr. Sect. D 52:93-104, 1996), which includes the site of PII modification, was not required for the binding of small-molecule effectors but was necessary for the interaction with all three receptors. Mutations altering residues of this loop or affecting the nearby B loop of PII, which line a cleft between monomers in the trimeric PII, affected the interactions with protein receptors and the binding of small-molecule ligands. Thus, our results support the predictions made from structural studies that the exposed loops of PII and cleft formed at their interface are the sites of regulatory interactions.

Probing interactions of the homotrimeric PII signal transduction protein with its receptors by use of PII heterotrimers formed in vitro from wild-type and mutant subunits

The homotrimeric PII signal transduction protein of Escherichia coli interacts with two small-molecule effectors, 2-ketoglutarate and ATP, regulates two protein receptors, the kinase/phosphatase nitrogen regulator II (NRII) and the glutamine synthetase (GS) adenylyltransferase (ATase), and is subject to reversible uridylylation, catalyzed by the uridylyltransferase/uridylyl-removing enzyme (UTase/UR). The site of PII uridylylation, Y51, is located at the apex of the solvent-exposed T-loop (E. Cheah, P. D. Carr, P. M. Suffolk, S. G. Vasudevan, N. E. Dixon, and D. L. Ollis, Structure 2:981-990, 1994), and an internally truncated PII lacking residues 47 to 53 formed trimers that bound the small-molecule effectors but were unable to be uridylylated or activate NRII and ATase (P. Jiang, P. Zucker, M. R. Atkinson, E. S. Kamberov, W. Tirasophon, P. Chandran, B. R. Schefke, and A. J. Ninfa, J. Bacteriol. 179:4342-4353, 1997). We investigated the ability of heterotrimers containing delta47-53 and wild-type subunits to become uridylylated and activate NRII and ATase. Heterotrimers were formed by denaturation and renaturation of protein mixtures; when such mixtures contained a fivefold excess of A47-53 subunits, the wild-type subunits were mostly redistributed into trimers containing one wild-type subunit and two mutant subunits. The resulting population of trimers was uridylylated and deuridylylated by UTase/UR, stimulated the phosphatase activity of NRII, and stimulated adenylylation of GS by ATase. In all except the ATase interaction, the activity of the hybrid trimers was greater than expected based on the number of wild-type subunits present. These results indicate that a single T-loop region within a trimer is sufficient for the productive interaction of PII with its protein receptors. We also formed heterotrimers containing wild-type subunits and subunits containing the G89A alteration (P. Jiang, P. Zucker, M. R. Atkinson, E. S. Kamberov, W. Tirasophon, P. Chandran, B. R. Schefke, and A. J. Ninfa, J. Bacteriol. 179: 4342-4353, 1997). The G89A mutant form of PII does not bind the small-molecule effectors, does not interact with UTase or with NRII, and interacts poorly with ATase. Heterotrimers formed with a 10/1 starting ratio of G89A to wild-type subunits interacted with UTase/UR and ATase to a lesser extent than expected based on the number of wild-type subunits present but activated NRII slightly better than expected based on the number of wild-type subunits present. Thus, intersubunit interactions within the PII trimer can adversely affect the activity of wild-type subunits and may affect the interactions with the different receptors in a variable way. Finally, we formed heterotrimers containing delta47-53 and G89A mutant subunits. These heterotrimers were not uridylylated, did not interact with NRII, and interacted with the ATase only to the extent expected based on the number of G89A subunits present. Thus, the G89A subunits, which contain an intact T-loop region, were not "repaired" by inclusion in heterotrimers along with delta47-53 subunits.

[Effect of perilymphatic fistula on distortion product otoacoustic emissions in guinea pigs]

Perilymphatic fistula was induced in 11 healthy guinea pigs to study its effects on distortion product otoacoustic emissions (DPOAEs). DPOAE amplitudes decreased significantly right after formation of the fistula (P < 0.01), and recurred to near pretreatment level in animals whose fistula healed. The amplitude remained below pretreatment level 18 days after fistulization in those animals whose fistula failed to heal. Under light microscope, the organ of Corti was seen normal. The authors feel that DPOAEs may be helpful in detecting perilymphatic fistula.

Risk of tongue cancer associated with tobacco smoking and alcohol consumption: a case-control study

Recent studies indicate that cancer of the tongue is increasing rapidly among the younger population in many parts of the world. Few studies, however, have directly examined the risk factors for the disease. A case-control study was conducted in Beijing, China to investigate risk factors for tongue cancer. A total of 111 cases and 111 controls aged 20-80 years were included in this study. The results show that risk of tongue cancer is significantly elevated among ex-smokers (OR = 2.24, 95% CI = 1.09-4.62) and among current smokers (OR = 2.73, 95% CI = 1.26-5.91). The risk increases with increasing tobacco consumption, as reflected by both cigarette equivalents smoked per day and lifetime pack-years of tobacco smoking. Quitting smoking was associated with a reduction of the risk of tongue cancer. The numbers of cases in the study, however, is small, preventing further analyses during the years after quitting smoking. Overall, alcohol drinking was not found to be significantly associated with the risk of tongue cancer in this study (OR = 1.20, 95% CI = 0.58-2.50 for current drinkers). However, a marginally significant association was found for those who drank spirits at least 5 days a week (OR = 2.34, 95% CI = 0.90-6.06). A suggestion of effect modification for smoking and alcohol drinking was observed in this study.

[The effect of far infrared rays on the survival of randomized skin flap in the rat: an experimental study]

In order to observe the effect of far infrared rays on the survival of skin flap, the following experiment was performed. Forty-eight SD rats were selected and divided into two groups. The rats received 0.3 w/cm2 radiation twice a day from 3 days before operation to 5 days after operation in the experimental group, while in the control group the rats received none before or after the operation. The flap was designed as 2 cm x 6 cm in the back of the rats with the pedicle caudalward. The microcirculatory changes of the flap were observed, and the survival area of the flap was calculated. The results showed that either in the proximal or in the distal part of the graft, in the experimental group, the mean opening rate, diameter and the flowing velocity of the microvessels were significantly higher than those in the control group (P < 0. 05). The mean rate of survival area of the experimental group (80.5%) was also higher than that of the control group (62.7%) (P < 0.01). It was suggested that radiation with far infrared rays could dilate the microvessels, improve the flap microcirculation, therefore, enhance the survival of the randomized skin flap.

Transcriptional activation of the human epidermal growth factor receptor promoter by human p53

The human epidermal growth factor receptor (EGFR) promoter is activated by both wild-type and tumor-derived mutant p53. In this communication, we demonstrate that EGFR promoter sequence requirements for transactivation by wild-type and mutant p53 are different. Transient-expression assays with EGFR promoter deletions identified a wild-type human p53 response element, 5'-AGCTAGACGTCCGGGCAGCCCCCGGCG -3', from positions --265 to --239. Electrophoretic mobility shift analysis and DNase I footprinting assays indicated that wild-type p53 binds sequence specifically to the response element. Using circularly permuted DNA fragments containing the p53-binding site, we show that wild-type p53 binding induces DNA bending at this site. We further show that the EGFR promoter is also activated by tumor-derived p53 mutants p53-143A, p53-175H, p53-248W, p53-273H, and p53-281G. However, the transactivation by mutant p53 does not require the wild-type p53-binding site. The minimal EGFR promoter from positions --104 to --20 which does not contain the wild-type p53-binding site is transactivated by the p53 mutants but not by the wild-type protein, showing a difference in the mechanism of transactivation by wild-type and mutant p53. Transactivation of the EGFR promoter by p53 may represent a novel mechanism of cell growth regulation.

Identification of a novel hypothalamic neuropeptide Y receptor associated with feeding behavior

Neuropeptide Y (NPY) plays important roles in the central control of appetite and energy balance, but the receptor subtype responsible for this function has not been cloned. Here we report the cloning by expression of a novel NPY receptor subtype from a rat hypothalamus cDNA library. The novel receptor, referred to as the NPY Y5 receptor, has a transcript of approximately 2.6 kilobases with an open reading frame of 1335 base pairs that encodes a 445-amino acid protein. The amino acid sequence deduced from the rat Y5 cDNA clone shows only 30-33% identity to other NPY receptors, including Y1, Y2, and Y4/PP1. Using the rat Y5 receptor cDNA probe, the human homologue was obtained by low stringency hybridization. The human Y5 amino acid sequence has 88% identity to the rat Y5 receptor. Importantly, pharmacological analysis shows that the rat and human Y5 receptors have high affinity for the peptides that elicit feeding (e.g. NPY, PYY, (2-36)NPY, and (LP)NPY) and low affinity for nonstimulating peptides (e.g. (13-36)NPY and rat PP), suggesting that it is the NPY feeding receptor subtype.

Generation of an integrated transcription map of the BRCA2 region on chromosome 13q12-q13

An integrated approach involving physical mapping, identification of transcribed sequences, and computational analysis of genomic sequence was used to generate a detailed transcription map of the 1. 0-Mb region containing the breast cancer susceptibility locus BRCA2 on chromosome 13q12-q13. This region is included in the genetic interval bounded by D13S1444 and D13S310. Retrieved sequences from exon amplification or hybrid selection procedures were grouped into physical intervals and subsequently grouped into transcription units by clone overlap. Overlap was established by direct hybridization, cDNA library screening, PCR cDNA linking (island hopping), and/or sequence alignment. Extensive genomic sequencing was performed in an effort to understand transcription unit organization. In total, approximately 500 kb of genomic sequence was completed. The transcription units were further characterized by hybridization to RNA from a series of human tissues. Evidence for seven genes, two putative pseudogenes, and nine additional putative transcription units was obtained. One of the transcription units was recently identified as BRCA2 but all others are novel genes of unknown function as only limited alignment to sequences in public databases was observed. One large gene with a transcript size of 10.7 kb showed significant similarity to a gene predicted by the Caenorhabditis elegans genome and the Saccharomyces cerevisiae genome sequencing efforts, while another contained a motif sequence similar to the human 2',3' cyclic nucleotide 3' phosphodiesterase gene. Several retrieved transcribed sequences were not aligned into transcription units because no corresponding cDNAs were obtained when screening libraries or because of a lack of definitive evidence for splicing signals or putative coding sequence based on computational analysis. However, the presence of additional genes in the BRCA2 interval is suggested as groups of putative exons and hybrid selected clones that were transcribed in consistent orientations could be localized to common physical intervals.

[Flavanonol glucosides of Smilax glabra Roxb]

Three flavanonol glucosides have been isolated from the rhizome of Smilax glabra. Their structures were identified as isoengetitin, isoastilbin and astilbin on the basis of their physicochemical and spectral data. Full as signment of their 1HNMR and 13CNMR chemical shift signals was established by various 2D-NMR techniques. Their glucosidic bond structures were determined for the first time. Isoastilbin was isolated from Smilax for the first time.

The complete BRCA2 gene and mutations in chromosome 13q-linked kindreds

Breast carcinoma is the most common malignancy among women in developed countries. Because family history remains the strongest single predictor of breast cancer risk, attention has focused on the role of highly penetrant, dominantly inherited genes in cancer-prone kindreds (1). BRCA1 was localized to chromosome 17 through analysis of a set of high-risk kindreds (2), and then identified four years later by a positional cloning strategy (3). BRCA2 was mapped to chromosomal 13q at about the same time (4). Just fifteen months later, Wooster et al. (5) reported a partial BRCA2 sequence and six mutations predicted to cause truncation of the BRCA2 protein. While these findings provide strong evidence that the identified gene corresponds to BRCA2, only two thirds of the coding sequence and 8 out of 27 exons were isolated and screened; consequently, several questions remained unanswered regarding the nature of BRCA2 and the frequency of mutations in 13q-linked families. We have now determined the complete coding sequence and exonic structure of BRCA2 (GenBank accession #U43746), and examined its pattern of expression. Here, we provide sequences for a set of PCR primers sufficient to screen the entire coding sequence of BRCA2 using genomic DNA. We also report a mutational analysis of BRCA2 in families selected on the basis of linkage analysis and/or the presence of one or more cases of male breast cancer. Together with the specific mutations described previously, our data provide preliminary insight into the BRCA2 mutation profile.

[A primary study on treatment of intracranial hematomas with specially designed needle puncture]

We treat hematomas by special designed needles and other techniques for breaking and liquefying hematoma. This method is easy to learn and needn't operation room, even can be done at the patient's bedside. Its merits the included point wound without craniotomy, low medical cost and satisfactory result. We treat 112 patients with hypertensive intracranial hematomas, 25 patients with acute epidural hamatoma and 17 patients with hematoma due to other causes. In the total of 154 patients, 20 had brain herniations and 104 coma. The mortality was very low (8.44%). 94 patients (91.34%) woke up in 1 to 2 weeks.

Comparative analysis of Homo sapiens and Mus musculus cyclin-dependent kinase (CDK) inhibitor genes p16 (MTS1) and p15 (MTS2)

Cyclin-dependent kinase inhibitors are a growing family of molecules that regulate important transitions in the cell cycle. At least one of these molecules, p16, has been implicated in human tumorigenesis while its close homolog, p15, is induced by cell contact and transforming growth factor-beta (TGF-beta). To investigate the evolutionary and functional features of p15 and p16, we have isolated mouse (Mus musculus) homologs of each gene. Comparative analysis of these sequences provides evidence that the genes have similar functions in mouse and human. In addition, the comparison suggests that a gene conversion event is part of the evolution of the human p15 and p16 genes.

[A comparative study on the chemical constituents of cultivated and wild fructus Gardeniae]

Studies have been made on the preliminary tests of the chemical constituents of cultivated and wild Fructus Gardeniae on the comparative analysis of the thin-layer chromatograms, IR and UV spectra of 95% ethanolic extracts as well as extracts obtained with four different solvents, and on the content determination of gardenosides. The results reveal that the cultivated and wild Fructus Gardeniae have similar chemical constituents, but differ in the contents of some constituents.

Genomic structure, expression and mutational analysis of the P15 (MTS2) gene

The P15 gene (MTS2) encodes a cyclin-dependent kinase (CDK) inhibitor with considerable sequence identity and biochemical similarity to the CDK inhibitor p16. It is closely linked to the P16 gene (MTS1) and is homozygously deleted in many tumor cell lines. These features suggest that p15 may be a tumor suppressor. We have determined the genomic structure of P15 and examined its pattern of mRNA expression. In addition, we have shown that ectopic expression of p15 inhibits growth of tumor-derived cell lines. We have also searched for P15 mutations in tumor cell lines and in 9p21-linked melanoma kindreds. Other than the previously described homozygous deletions, no mutations of P15 were found. Collectively, these observations suggest a role for p15 in growth regulation, but a limited role for p15 in tumor progression.

[Experimental study of radioimmunotherapy for xenograft of human esophageal carcinoma]

Using nude mice bearing human esophageal carcinoma strain Eca 109 as models of tumor, we tested the therapeutic efficiency of 131I labelled monoclonal antibody MGb2 A 4-week experimental study was carried out in 5 treatment groups: group A, buffer, group B, unlabelled MGb2; group C, 131I-labelled normal mice IgG and group D, 131I-labelled MGb2 18.5MBq. All nude mice above were given agents intraperitoneally. In group E, the animals were given 131I-labelled MGb2 18.5MBq by intratumoral administration. The results showed that from the second week, in group D and E the tumor volume was remarkably decreased as compared with that of the other 3 groups (P < 0.01 or P < 0.05). In the fourth week the mean volume in group D and E were 0.55 cm3 and 0.23cm3, while in group A, the volume was 1.43cm3. The inhibition rate of tumor growth in group D and E was higher than in other groups from the second week (P < 0.01), especialy in the third and fourth week with a mean value of 62. 4%, 61.5% and 82.2%, 83.9% respectively. There were no significant differences between group A, B, and C in tumor volume or growth inhibition rate.

Complex structure and regulation of the P16 (MTS1) locus

The p16 gene (P16, MTS1, CDKN2) encodes a negative regulator of the cell cycle. Molecular genetic techniques have been used to explore the role of p16 in normal development and cancer. Two transcripts derived from the p16 gene with distinct protein coding potentials are described. The previously undescribed transcript form has the same exons 2 and 3 as the p16-encoding mRNA but contains a different exon 1. The human p16 transcripts are detected in various tissues, and the ratio of the transcripts is regulated in both a tissue-specific and cell cycle-specific manner. The P16-derived mRNAs are probably generated from separate promoters, and transcription from one of the promoters appears to be regulated, at least in part, by the retinoblastoma gene product.

[Effect of glucocorticoids and other steroids on arginine vasopressin release from rat hypothalamic slices]

Rat hypothalamic slices sectioned with vibratome (containing paraventricular and supraoptic nuclei) were incubated in static microchamber and the Arginine vasopressin (AVP) released from the slices was measured by radioimmunoassay. The effect of glucocorticoids (GC) and other steroids on AVP release was investigated. The results were as follows: (1) AVP was steadily released at a rate of 9.06 +/- 1.23 pg/min for as long as 6 h (not including the 90 min for recovery of slices). (2) Corticosterone (B) inhibited AVP release within 20 min in a dose-dependent manner from 10(-7) to 10(-4) mol/L. (3) Cortisol, 17 beta-estradiol, or testosterone (10(-6) mol/L) also inhibited AVP release within 20 min, but dexamethasone, aldosterone, progesterone, RU486, or cholesterol had no significant effect. (4) RU486 (10(-5)-10(-3) mol/L) could partially block the rapid inhibitory effect of corticosterone. These results suggested that GC might exert in situ a regulatory negative feedback action on the AVP release from hypothalamus of rat through a non-genomic rather than a genomic mechanism.

The effect of hypothermia on transient focal ischemia in rat brain evaluated by diffusion- and perfusion-weighted NMR imaging

The effect of moderate whole-body hypothermia (30 degrees C) on transient middle cerebral artery (MCA) occlusion in the rat was evaluated using diffusion- and perfusion-weighted magnetic resonance imaging. Two hours of transient MCA occlusion was induced by intracarotid insertion of a nylon filament under normothermic (n = 14) and hypothermic (n = 7) conditions. Diffusion- and perfusion-weighted imaging were performed before, during, and after focal ischemia from 30 min up to 7 days. In hypothermic animals, scattered neuronal necrosis was localized to select areas of the caudate putamen and the parietal and insular cortex. In contrast, the normothermic ischemic animals exhibited pan-necrosis and infarct encompassing the damaged area. The diffusion and perfusion data measured from caudate putamen indicate that hypothermia causes a significant reduction in the apparent diffusion coefficient of water (ADCw) and CBF values from normothermic control values (p < 0.01). In both normothermic and hypothermic animals after onset of MCA occlusion, ADCw and CBF values in the core of the ischemic region (striatum) significantly declined from the preischemic and homologous contralateral control ADCw and CBF values (p < 0.05). However, ADCw and CBF in the hypothermic group returned toward control more rapidly than in the normothermic group. These results suggest that the protective effect of hypothermia on ischemic cell damage is reflected in the early return of ADCw during reperfusion and the reduction of ischemic cell damage by hypothermia may be mediated by the improved CBF during acute reperfusion.

Inhibition of fatty acid synthesis in Escherichia coli in the absence of phospholipid synthesis and release of inhibition by thioesterase action

The effects of inhibition of Escherichia coli phospholipid synthesis on the accumulation of intermediates of the fatty acid synthetic pathway have been previously investigated with conflicting results. We report construction of an E. coli strain that allows valid [14C]acetate labeling of fatty acids under these conditions. In this strain, acetate is a specific precursor of fatty acid synthesis and the intracellular acetate pools are not altered by blockage of phospholipid synthesis. By use of this strain, we show that significant pools of fatty acid synthetic intermediates and free fatty acids accumulate during inhibition of phospholipid synthesis and that the rate of synthesis of these intermediates is 10 to 20% of the rate at which fatty acids are synthesized during normal growth. Free fatty acids of abnormal chain length (e.g., cis-13-eicosenoic acid) were found to accumulate in glycerol-starved cultures. Analysis of extracts of [35S]methionine-labeled cells showed that glycerol starvation resulted in the accumulation of several long-chain acyl-acyl carrier protein (ACP) species, with the major species being ACP acylated with cis-13-eicosenoic acid. Upon the restoration of phospholipid biosynthesis, the abnormally long-chain acyl-ACPs decreased, consistent with transfer of the acyl groups to phospholipid. The introduction of multicopy plasmids that greatly overproduced either E. coli thioesterase I or E. coli thioesterase II fully relieved the inhibition of fatty acid synthesis seen upon glycerol starvation, whereas overexpression of ACP had no effect. Thioesterase I overproduction also resulted in disappearance of the long-chain acyl-ACP species. The release of inhibition by thiosterase overproduction, together with the correlation between the inhibition of fatty acid synthesis and the presence of abnormally long-chain acyl-ACPs, suggests with that these acyl-ACP species may act as feedback inhibitors of a key fatty acid synthetic enzyme(s).

Developmental and glucocorticoid modulation of the expression of mRNAs for Gs alpha and G beta subunits in neonatal liver

The mRNA levels for Gs alpha and G beta in liver from various age groups of rabbits were assessed by Northern and dot-blot hybridization assays using cDNA and oligonucleotide probes. The mRNA levels for both Gs alpha and G beta exhibited a transient 30-35% decrease at 3-6 h after birth, followed by a 3- to 3.5-fold increase which peaked at 2 days after birth, then gradually declined to adult levels at 4-6 weeks. The changes in mRNA levels paralleled the changes in protein levels [previously measured by immunoblotting (Kawai and Arinze, 1991)] in the first 2 days after birth, but not in the later periods of development. Beyond day 3, the increase in protein levels persists, reaching maximal levels at 4 weeks and equalling adult levels while their mRNA levels decrease to about 50% of the levels at day 2. In vivo administration of dexamethasone to neonatal rabbits increased hepatic mRNA levels for both Gs alpha and G beta by about 50%; the effect was moderate compared to the 2- to 3-fold increase in corresponding protein levels. The transcription rate for the Gs alpha gene increased by only 32% at day 2 after birth compared to term. A 68% increase in transcription rate for this gene was observed after the dexamethasone treatment. Taken together, these data indicate that the developmental and glucocorticoid-regulated expression of Gs alpha- and G beta-subunits in neonatal liver is modulated at the transcriptional level.

Method for determining the reliable prediction(s) of compositions of tissue phantoms

In a previous paper, we showed that mixture laws can be used to predict the compositions of tissue phantoms. Due to the variation in the performance of the mixture laws when they are applied to phantoms, however, it is difficult to determine which predictions of the composition are most reliable. In this paper, we study the causes of the variation in the performances of different sets of mixture laws, and propose a criterion for choosing a reliable predictor. The predictions selected with the proposed criterion agree very well with the known compositions of phantoms. The potential uses of the mixture methodology and the criterion to tissue characterization are discussed.

Genetic analysis of the agrocinopine catabolic region of Agrobacterium tumefaciens Ti plasmid pTiC58, which encodes genes required for opine and agrocin 84 transport

The acc region, subcloned from pTiC58 of classical nopaline and agrocinopine A and B Agrobacterium tumefaciens C58, allowed agrobacteria to grow using agrocinopine B as the sole source of carbon and energy. acc is approximately 6 kb in size. It consists of at least five genes, accA through accE, as defined by complementation analysis using subcloned fragments and transposon insertion mutations of acc carried on different plasmids within the same cell. All five regions are required for agrocin 84 sensitivity, and at least four are required for agrocinopine and agrocin 84 uptake. The complementation results are consistent with the hypothesis that each of the five regions is separately transcribed. Maxicell experiments showed that the first of these genes, accA, encodes a 60-kDa protein. Analysis of osmotic shock fractions showed this protein to be located in the periplasm. The DNA sequence of the accA region revealed an open reading frame encoding a predicted polypeptide of 59,147 Da. The amino acid sequence encoded by this open reading frame is similar to the periplasmic binding proteins OppA and DppA of Escherichia coli and Salmonella typhimurium and OppA of Bacillus subtilis.

The acquisition of lysophosphatidylcholine by African trypanosomes

Bloodstream forms of the African trypanosome, Trypanosoma brucei, can acquire substantial amounts of exogenous lysophospholipid. Lysophosphatidylcholine uptake is through a pathway consisting of three enzymes, phospholipase A1, acyl-CoA ligase, and lysophosphatidylcholine:acyl-CoA acyltransferase. The pathway enables the organism to acquire fatty acids and phospholipid head groups such as choline. Radiolabeling and 13C NMR studies show that two molecules of lysophosphatidylcholine are used to generate one molecule of cellular phosphatidylcholine. The three enzymes are associated with the trypanosomal plasma membrane and are accessible to exogenous substrates. The first enzyme, phospholipase A1, generates free fatty acid from exogenous lysophospholipid, which the second enzyme, a ligase, uses to form acyl-CoA. The fatty acyl-CoA formed by this route is in a separate pool from that derived from exogenous free fatty acid and is used by the third enzyme, acyltransferase, to acylate a second molecule of exogenous lysophospholipid. Acyltransferase is accessible to exogenous and endogenous acyl-CoA. The high activity of this pathway in bloodstream forms, compared with procyclic culture form trypanosomes, suggests that it may play a role in the acquisition of fatty acids for synthesis of the membrane form of the variant surface glycoprotein. Extracellular myristoyllysophosphatidylcholine can be used by trypanosomes as a source of myristate in remodeling the lipid anchor of the variant surface glycoprotein.

Spectral measurements of NH(3) absorption lines by a 1.5-microm grating-external-cavity semiconductor laser

Forty-four NH(3) absorption spectral lines of the combination tones of the vibration-rotation transitions were observed at 1.4988-1.5520 microm with a 1.5-microm grating-external-cavity semiconductor laser. The linewidth and absorption rate of NH(3) absorption spectral lines were measured. Also, the changes of center frequency and linewidth of the NH(3) absorption spectral line with the our knowledge the first time.

Treatment of ovarian malignant germ cell tumors with preservation of fertility

Conservative operation and postoperative chemotherapy were given to 15 patients with malignant germ cell tumors of the ovary with the preservation of fertility and ovarian functions. Four patients, one with endodermal sinus tumor and three immature teratoma, had full term deliveries after the operation. The possibility was discussed to preserve young women's fertility and ovarian function in treating their malignant germ cell tumors.

Conformation of a synthetic hexapeptide substrate of collagen lysyl hydroxylase

The hexapeptide Hyp-Gly-Pro-Lys-Gly-Glu was synthesized as a potential substrate for collagen lysyl hydroxylase. Kinetic data on the interaction of this peptide with purified chicken embryo lysyl hydroxylase showed that the hexapeptide is a moderately good substrate having Km, Vmax, and Kcat/Km values comparable to those of synthetic peptide substrates having longer chain lengths. Circular dichroism spectral data suggested a consecutive beta turn or 3(10) helical conformation for the peptide in trifluoroethanol. The two-dimensional 1H-TOCSY spectrum of the peptide in dimethylsulfoxide permitted complete assignment of all the protons in the hexapeptide. Through-space connectivities between protons in the peptide molecule were obtained from two-dimensional 1H-NOESY spectral data on the peptide. Using the distances calculated from these data as input constraints, the minimum-energy conformation of the peptide was computed. These calculations and an unconstrained Monte Carlo molecular simulation both led to a folded conformation for the hexapeptide with dihedral angles close to a set of consecutive beta turns as the lowest-energy conformer. This structure is stabilized further by a salt bridge between the side chains of Lys4 and Glu6. Several other conformers energetically close to the minimum-energy conformer exhibited the structural features of the latter except for variations at the N-terminal end and in the side chains. In conjunction with data obtained earlier on lysyl hydroxylase (P. Jiang and V. S. Ananthanarayanan, 1991, J. Biol. Chem. 266, 22960-22967) and the functionally related prolyl hydroxylase (P. L. Atreya and V. S. Ananthanarayanan, 1991, J. Biol. Chem. 266, 2852-2858), the present results suggest that the folded beta turn in the respective peptide substrate may be the structural determinant at the catalytic sites of these enzymes. Additional structural features may govern the effective binding of the peptide at the enzymes' active sites.

[Chemical constituents of Eupolyphaga sinensis Walker]

Five compounds were isolated from the n-hexane extract and n-butanol of extract Eupolyphaga sinensis. These compounds were identified as octacosanol, beta-sitosterol, batyl alcohol, 2,4-pyrimidinedione and allantoin.

Conformational requirement for lysine hydroxylation in collagen. Structural studies on synthetic peptide substrates of lysyl hydroxylase

An attempt has been made to understand the conformational determinants that govern the hydroxylation of selected lysyl residues in the nascent collagen molecule by lysyl hydroxylase (EC 1.14.11.4). A series of peptide substrates of the enzyme, ranging in length from 3 to 12 residues, were synthesized. These included: tert-butyloxylcarbonyl (t-Boc)-Ile-Lys-Gly; Boc-Ala-Lys-Gly; N-acetyl-Ala-Lys-Gly-Ser; Hyp-Gly-Pro-Lys-Gly-Glu; Leu-Hyp-Gly-Ala-Lys-Gly-Glu; Gly-Phe-Hyp-Gly-Leu-Hyp-Gly-Ala-Lys-Gly-Glu; (Hyp-Gly-Pro-Lys-Gly-Glu)2; and Ala-Arg-Gly-Ile-Lys-Gly-Ile-Arg-Gly-Phe-Ser-Gly. The conformational features of these peptides were studied by spectroscopic methods so as to relate this information with the kinetic parameters for the interaction of these peptides with purified lysyl hydroxylase. Spectroscopic data, supported by conformational energy calculations, indicated that the tripeptides t-Boc-Ile-Lys-Gly and t-Boc-Ala-Lys-Gly adopt a gamma-turn structure in water and trifluoroethanol with Lys in the second position of the turn. In the tetra- and larger peptides two structures, the beta-turn and a polyproline-II (PP-II) type extended conformation, were identified. The proportions of these two structures in a given peptide depended on the polarity of the solvent. All of the peptides were hydroxylated by lysyl hydroxylase isolated from chicken embryos. In contrast, a control peptide, t-Boc-Ala-Gly-Lys which adopted a beta-turn with Lys at the end of the turn, was not hydroxylated. Competitive inhibition of the hydroxylation of protocollagen by some of the peptides showed a common binding site for these substrates in the enzyme's active site. Kinetic data on the peptides indicated improved hydroxylation rate (higher Vmax) in peptides having relatively higher beta-turn content and improved binding (lower Km) in peptides with higher content of the PP-II structure. The efficacy of the substrate was also governed by its chain length. These data suggest that the conformational criterion for lysine hydroxylation in collagen-related peptides is the presence of a "bent" structure, such as the gamma- or beta-turn at the catalytic site of lysyl hydroxylase and an "extended" PP-II type structure at the binding site(s) of the enzyme's active site. This suggestion also provides a conformational rationale for earlier observations on the substrate specificity of lysyl hydroxylase.