The regulating effects of protein kinase C on the tone of guinea-pig trachea and human lobus bronchi

The regulating effects of protein kinase C (PKC) on the tone of guinea-pig trachea and human lobus bronchi were investigated by measuring the tone of isolated tracheal and bronchial strips. The effects of PKC on the tone of guinea-pig tracheal and human lobus bronchi were observed and compared. The results showed that: (1) PKC activator PMA induced concentration-dependent relaxation in guinea-pig isolated trachea strips. This relaxation was completely ablated by the pretreatment with 5 x 10(-6) mol/L Ro31-8220 which is a PKC-specific inhibitor, but was not affected by the removal of epithelium (EP), or by the pretreatment with propranolol (beta-receptor blocker) or atropin (M-receptor blocker); (2) PMA led to concentration-dependent contraction in human lobus bronchi. This contractile response was completely depressed by the pretreatment with 5 x 10(-6) mol/L Ro31-8220 and was partly inhibited by 1 x 10(-5) mol/L isoptin (Ca(2+)-antagonist), but was not significantly affected by propranolol or atropin. It is concluded that PKC is involved in the regulation of airway smooth muscle tone. The regulating effects may vary in different animals.

Mammography underutilization among older women in Connecticut

OBJECTIVES

The primary goals were to examine mammography use rates among older women in Connecticut and to determine if there was significant variation among different areas and racial groups in the state. The secondary goal was to examine what impact the initiation of Medicare reimbursement for mammography screening has had on mammography use.

DESIGN

Statewide use rates were determined by retrospective Medicare Part B mammography claims analysis. Small area analysis methodology (SAA) was used to identify mammography rates for 23 hospital service areas (HSAs), representing all of the catchment areas for Connecticut's acute care hospitals.

PARTICIPANTS

Female Medicare beneficiaries 65 years and older with Part B coverage residing in Connecticut during the study period.

MEASUREMENTS

The main outcome (the use of at least one mammogram) was calculated for the calendar years 1991, 1992, and 1993. Mean annual use rates in 1993 were generated for the 23 HSAs and the different racial groups in Connecticut. To examine the effect that Medicare reimbursement for screening mammograms has had on mammography use, rates were calculated for women who met Medicare reimbursement criteria in 1991 through 1993. The rates in 1992 and 1993 were then compared with those in 1991, when the reimbursement program was first initiated.

MAIN RESULTS

The mean statewide annual rates among women aged 65 years and older were 23.4% (1991), 24.5% (1992), and 24.9% (1993). The mammography use rates among black women 65 years and older were significantly lower than their white peers in 1991 (18.8% black vs 23.8% white, P < .001), 1992 (20.6% vs 24.7%, P < .001), and 1993 (22.0% vs 25.1%, P < .001). Significant variation was identified among hospital service areas (HSAs) within the state for each time interval studied. The use rates among women aged 65 years and older who were eligible for Medicare screening mammography reimbursement increased significantly from 14.6% in 1991, when Medicare reimbursement for screening mammograms was first initiated, to 18.9% in 1992 (P < .001). The rates in 1993 (17.4%) also increased from the baseline year 1991 (P < .001). However, the observed increases since 1991 have been limited in magnitude.

CONCLUSIONS

Low mammography use persists among older women in Connecticut and, in particular, among older black women. The initiation of Medicare reimbursement for screening mammograms in 1991 has had some impact on mammography use although its effects are still limited. Through the use of small area analysis methodology, significant underutilization of mammography in localized areas of the state was identified. These findings have facilitated local outreach interventions. Additional research is needed to understand if health service barriers are contributing to the local variation in rates observed in this study.

Impaired brain development and reduced astrocyte response to injury in transgenic mice expressing IGF binding protein-1

Numerous reports indicate that insulin-like growth factor-I (IGF-I) has a critical role in brain development, that it contributes to neuronal survival and that its activity is regulated by a family of IGF binding proteins (IGFBPs). In the present study, brain development was investigated in transgenic (Tg) mice that overexpress rat IGFBP-1 under the control of phosphoglycerate kinase promoter. Adult Tg mice had significantly decreased brain weight (299 +/- 17 vs. 499 +/- 11 mg), brain DNA content (684 +/- 8 vs. 810 +/- 31 microg) and brain protein (37 +/- 1 vs. 48 +/- 2 mg) compared with wild-type (Wt) mice and these deficits were already evident at birth. In Tg mice, myelin staining was generally reduced and there was a diminished thickness of the corpus callosum. The total area of hippocampus and dentate gyrus were significantly reduced by 55% and 72%, respectively. Bromodeoxyuridine labeling of proliferating cells in 3-day-old mice was markedly reduced by 41% in the dentate gyrus and by 19% in ventricular zones of Tg mice. Reactive astrogliosis reflected by morphology and glial fibrillary acidic protein expression of astrocytes in response to a mechanical lesion was substantially less in Tg compared with Wt mice. Mixed glial cell cultures from Tg animals were significantly less responsive to stimulation of proliferation by IGF-I than cultures from Wt mice. We conclude that overexpression of IGFBP-1 impairs brain development and reduces glial cell proliferation in response to injury.

Reduced Lignin Content and Altered Lignin Composition in Transgenic Tobacco Down-Regulated in Expression of L-Phenylalanine Ammonia-Lyase or Cinnamate 4-Hydroxylase

We analyzed lignin content and composition in transgenic tobacco (Nicotiana tabacum) lines altered in the expression of the early phenylpropanoid biosynthetic enzymes L-phenylalanine ammonia-lyase and cinnamate 4-hydroxylase (C4H). The reduction of C4H activity by antisense expression or sense suppression resulted in reduced levels of Klason lignin, accompanied by a decreased syringyl/guaiacyl monomer ratio as determined by pyrolysis gas chromatography/mass spectrometry Similar reduction of lignin levels by down -regulation of L-phenylalanine ammonia-lyase, the enzyme preceding C4H in the central phenylpropanoid pathway, did not result in a decreased syringyl/guaiacyl ratio. Rather, analysis of lignin methoxyl content and pyrolysis suggested an increased syringyl/guaiacyl ratio. One possible explanation of these results is that monolignol biosynthesis from L-phenylalanine might occur by more than one route, even at the early stages of the core phenylpropanoid pathway, prior to the formation of specific monolignol precursors.

[Experimental study prevention of reperfusion injury of skeletal muscle by local hypothermia and its clinical application]

Local hypothermia as a preventive method to reperfusion injury of skeletal muscles was studied. Sixteen Japanese rabbits were divided into four groups at random. Before the tourniquet was inflated, a cold gel pack was applied to the right hind leg of each rabbit for 15 minutes to produce local hypothermic condition, without application of tourniquet the left hind limb was under local hypothermic condition as a control. The duration of tourniquet ischemia was 4 hours, and then reperfusion for one and two hours in the A and B groups respectively; in the C and D groups the duration of ischemia was 5 hours, and reperfusion for one and two hours, respectively. The muscle temperature averaged 16.6 degrees C with a needle thermocouple in the hind limb under local hypothermia. The serum K+, LA, SOD, LPO were determined from bilateral femoral veins, and electron and light microscopic studies of sural muscles were done in the post-reperfusion period. It was found that the K+, LA, LPO were lower than that of the control groups (P < 0.01), but SOD was higher than that of the control group (P < 0.01). Electron and light microscopic studies showed sight but reversible damage of muscular structure with the possibility of in the hypothermic groups cell regeneration. Basing on this experimental results, this method was applied in 45 cases reparative and reconstructive surgery of limbs. The duration of application of tourniquet averaged 2 hours and 57 minutes, the longest being 4 hours and 31 minutes, when the muscle temperature had reduced to 22.4 degrees C. There were no postoperative complications associated with this technique. Local hypothermia appeared to be a safe and effective method of decreasing the reperfusion damage after ischemia.

Stress Responses in Alfalfa (XXI. Activation of Caffeic Acid 3-O-Methyltransferase and Caffeoyl Coenzyme A 3-O-Methyltransferase Genes Does Not Contribute to Changes in Metabolite Accumulation in Elicitor-Treated Cell-Suspension Cultures)

Transcription of genes encoding L-phenylalanine ammonia-lyase (PAL), the first enzyme of the phenylpropanoid pathway, and caffeic acid 3-O-methyltransferase (COMT) and caffeoyl CoA 3-O-methyltransferase (CCOMT), enzymes involved in the synthesis of lignin and wall-esterified phenolic compounds, was strongly activated in elicitor-treated cell-suspension cultures of alfalfa (Medicago sativa L.). However, consequent changes in the extractable activities of COMT and CCOMT were small to nonexistent compared with a 15- to 16-fold increase in PAL activity. Only low levels of COMT and CCOMT transcripts were reflected in the total and polysomal RNA fractions compared with PAL transcripts. Elicited cell cultures did not accumulate lignin or the products of COMT and CCOMT in the soluble and wall-esterified phenolic fractions. In one alfalfa cell line in which elicitation resulted in very high PAL activity and increased deposition of methoxyl groups in the insoluble wall fraction, there was still no change in COMT and CCOMT activities. Overall, these results indicate that the initial gene transcription events in elicited cells may be less selective than the subsequent metabolic changes, highlighting the importance of posttranscriptional events in the control of phenylpropanoid biosynthesis.

Stress responses in alfalfa (Medicago sativa L.). XX. Transcriptional activation of phenlpropanoid pathway genes in elicitor-induced cell suspension cultures

Nuclear transcript run-on analysis was used to investigate++ the relative transcription rates of genes encoding enzymes of isoflavonoid phytoalexin biosynthesis and related pathways in elicitor-treated alfalfa (Medicago sativa L.) cell suspension cultures. Genes encoding L-phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS) and chalcone reductase (CHR) were most rapidly activated, with increases in transcription measurable within 10-20 min after elicitation. Cinnamic acid 4-hydroxylase (C4H), chalcone isomerase (CHI), isoflavone reductase (IFR) and caffeic acid 3-0-methyltransferase (COMT) genes were also rapidly activated, but at a slower initial rate. Transcription of chalcone 2'-O-methyltransferase (CHOMT), and 1,3-beta-D-glucanase genes was less rapid, with lag periods of 60 and 30 min post-elicitation, respectively. Treatment of cells with a PAL inhibitor L-alpha-aminooxy-beta-phenylpropionic acid (AOPP) resulted in increased transcription of PAL, CHS and CHR, but reduced transcription of CHOMT, indicating a role for phenylpropanoid products as both negative and positive regulators of gene expression within the phenylpropanoid pathway.

Tasks and timing in the perception of linguistic anomaly

Three experiments were conducted to investigate the relative timing of syntactic and pragmatic anomaly detection during sentence processing. Experiment 1 was an eye movement study. Experiment 2 employed a dual-task paradigm with compressed speech input, to put the processing routines under time pressure. Experiment 3 used compressed speech input in an anomaly monitoring task. The outcomes of these experiments suggest that there is little or no delay in pragmatic processing relative to syntactic processing in the comprehension of unambiguous sentences. This narrows the possible explanations for any delays that are observed in the use of pragmatic information for ambiguity resolution.

Stress responses in alfalfa (Medicago sativa L.) XIX. Transcriptional activation of oxidative pentose phosphate pathway genes at the onset of the isoflavonoid phytoalexin response

We have isolated cDNA clones encoding the pentose phosphate pathway enzymes 6-phosphogluconate dehydrogenase (6PGDH, EC 1.1.1.44) and glucose 6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) from alfalfa (Medicago sativa L.). These exhibit extensive nucleotide and amino acid sequence similarity to the corresponding genes from bacteria, Drosophila and mammals. Transcripts encoding both enzymes are expressed at high levels in roots and nodules. Exposure of alfalfa suspension cells to an elicitor from yeast cell walls results in co-ordinated increases in transcription rates for both genes, followed by increased steady state transcript levels but only slightly increased extractable enzyme activities, at the onset of accumulation of isoflavonoid phytoalexins. Levels of NADPH and NADP remain relatively constant in alfalfa cells following elicitation. The rapid transcriptional activation of 6PGDH and G6PDH does not therefore appear to be a response to altered pyridine nucleotide redox state. These genes appear to respond to early events in elicitor-mediated signalling rather than to subsequent elicitor-induced changes in secondary metabolism. Hydrogen peroxide, a potential signal for elicitation of anti-oxidative genes in biologically stressed plant cells, did not induce 6PGDH or G6PDH transcripts or enzymatic activity.

Increased disease susceptibility of transgenic tobacco plants with suppressed levels of preformed phenylpropanoid products

It has been proposed that natural products synthesized by plants contribute to their resistance to pests and pathogens. We show here that transgenic tobacco plants with suppressed levels of the phenylpropanoid biosynthetic enzyme phenylalanine ammonia-lyase (L-phenylalanine ammonia-lyase, EC 4.3.1.5) and correspondingly low levels of chlorogenic acid, the major soluble leaf phenylpropanoid product, exhibit more rapid and extensive lesion development than wild-type plants after infection by the virulent fungal pathogen Cercospora nicotianae. These observations provide direct evidence that phenylpropanoid products contribute to disease limitation. No induction of transcripts encoding phenylalanine ammonia-lyase or the lignin branch pathway enzyme caffeic acid O-methyltransferase was observed during the infection and there was no perturbation in the pattern of soluble phenylpropanoids. Hence, increased disease susceptibility does not involve inhibition of a pathogen-induced response but likely reflects inhibition of the developmental accumulation of chlorogenic acid. Demonstration of the contribution of such preformed protectants to plant health identifies attractive targets for manipulation by breeding or gene transfer to reduce the quantitative impact of disease.

Quantitative relationship between phenylalanine ammonia-lyase levels and phenylpropanoid accumulation in transgenic tobacco identifies a rate-determining step in natural product synthesis

Phenylalanine ammonia-lyase (PAL) catalyzes the first step in phenylpropanoid synthesis. The role of PAL in pathway regulation was investigated by measurement of product accumulation as a function of enzyme activity in a collection of near-isogenic transgenic tobacco plants exhibiting a range of PAL levels from wild type to 0.2% of wild type. In leaf tissue, PAL level is the dominant factor regulating accumulation of the major product chlorogenic acid and overall flux into the pathway. In stems, PAL at wild-type levels contributes, together with downstream steps, in the regulation of lignin deposition and becomes the dominant, rate-determining step at levels 3- to 4-fold below wild type. The metabolic impact of elevated PAL levels was investigated in transgenic leaf callus that overexpressed PAL. Accumulation of the flavonoid rutin, the major product in wild-type callus, was not increased, but several other products accumulated to similarly high levels. These data indicate that PAL is a key step in the regulation of overall flux into the pathway and, hence, accumulation of major phenylpropanoid products, with the regulatory architecture of the pathway poised so that downstream steps control partitioning into different branch pathways.