Amniotic fluid interleukin-10 (IL-10) concentrations during pregnancy and with labor

To determine if amniotic fluid interleukin-10 (IL-10) concentrations are elevated in women with labor, either at term or preterm, and in the setting of infection-associated preterm labor, amniotic fluid samples were collected from women: (1) at term, not in labor (n = 42); at term, in labor (n = 56), preterm contractions, undelivered within 1 week (n = 22), and preterm labor, delivered within 1 week (n = 31). IL-10 concentrations were assayed in each sample via ELISA (Pharmingen, San Diego, CA). In a subsequent analysis, 8 women with preterm labor associated with chorioamnionitis were matched for gestational age with women experiencing preterm contractions (undelivered within 7 days) and preterm labor (delivered within 7 days) and amniotic fluid IL-10 concentrations compared. Approximately 40-70% of amniotic fluid samples obtained from women in each group had detectable IL-10. However, there were no significant differences in amniotic fluid IL-10 concentrations among the patients. While 1 of 8 patients with chorioamnionitis had amniotic fluid IL-10 concentrations greater than 300 pg/ml, there were no statistically significant differences among the matched samples. Amniotic fluid IL-10 concentrations were not elevated in women with term labor, preterm labor, or chorioamnionitis. This finding contrasts with the elevated concentrations of pro-inflammatory cytokines and chemokines such as interleukin-1, tumor necrosis factor-alpha, IL-6, IL-8, MIP-1 alpha, and GRO alpha reported in previous studies. Because we did not detect elevations of the key anti-inflammatory cytokine IL-10 in amniotic fluid of women with infection-associated preterm labor, we suggest that anti-inflammatory processes in this setting may be attenuated.

Alterations of GABAA receptor subunit mRNA levels in the aging Fischer 344 rat inferior colliculus

The inhibitory neurotransmitter, gamma-aminobutyric acid (GABA) is critically involved in shaping neuronal responses to simple and complex acoustic stimuli in the central auditory structure, the inferior colliculus (IC). Studies in rat and human suggest that age-related changes in markers for GABA neurotransmission occur in the IC. In particular, these changes include findings indicative of an age-related increase in the efficacy/potency of GABA to inhibit ligand binding at the GABAA receptor picrotoxin site in the Fischer (F344) rat IC. Such changes in GABAA receptor modulation suggest the potential for an alteration in GABAA receptor subunit composition in the old rat IC. To test this idea, the present study used in situ hybridization to quantify age-related changes in GABAA receptor subunit mRNA levels in the three major subdivisions of the IC in the F344 rat: dorsal cortex (DCIC), external cortex (ECIC), and the central nucleus (CIC). In support of earlier findings of an age-related change in GABAA receptor modulation, the present study found: (1) GABAA receptor subunit mRNA levels were significantly altered in the IC of old rats, and (2) age-related changes in subunit levels appeared to be regionally selective and subunit specific. A highly significant increase in the level of the gamma 1 subunit mRNA was observed with little change in the levels of the alpha 1, beta 2, and gamma 2 subunit mRNAs. A nonstatistically significant increase in alpha 2 subunit mRNA was also observed. This observed increase in alpha 2 subunit mRNA could be important since previous expression studies have shown that the alpha 2 and gamma 1 subunits coassemble and are incorporated into GABAA receptors which appear to be more sensitive to GABA. If the observed changes in subunit mRNA levels with age correlate well with enhanced GABAA receptor function in the IC of old rats, this, in turn, may represent a compensatory mechanism in response to presynaptic GABAergic changes.

Elevated concentrations of prorenin and renin in amniotic fluid of women with chorioamnionitis

OBJECTIVE

The objective of this study was to determine the concentrations of prorenin and renin in amniotic fluid of women under various physiologic and pathologic conditions.

METHODS

Amniotic fluid was collected from women with chorioamnionitis treated in the Labor and Delivery Unit, University of Utah Medical Center, and from gestation-matched control women with preterm labor who were delivered within 1 week and later than 1 week and at term in labor or not in labor. Prorenin and renin concentrations were measured in these fluids by a direct immunoradiometric assay.

RESULTS

Large amounts of prorenin and renin were detected in all samples with 85% to 95% in the form of prorenin. Concentrations of both prorenin and renin were significantly higher in the amniotic fluid of women with chorioamnionitis than in the amniotic fluid of control women. There were no other significant differences between the groups.

CONCLUSIONS

Our data indicate that amniotic fluid concentrations of renin and prorenin are elevated in women with clinically evident chorioamnionitis. We suggest that these elevations reflect a possible role for renin and prorenin in the pathophysiologic process of intrauterine infection-associated preterm labor.

The relationship of ambulation in labor to operative delivery

An abbreviated version of the Nurse-Midwifery Clinical Data Set was used to gather data on all women (n = 3,049) who began intrapartum care with a nurse-midwife in three sites. Demographic information, intrapartum care, and outcomes were recorded. The association of ambulation in labor with operative delivery was examined in a low-risk sample (n = 1,678) of women who did not receive care measures (epidural anesthesia, oxytocin induction or augmentation) that preclude mobility in labor. Women who ambulated for a significant amount of time during labor (compared with those who did not ambulate) had half the rate of operative delivery (2.7% vs. 5.5%).

Value of fetal fibronectin as a predictor of preterm delivery for a low-risk population

OBJECTIVE

We examined clinical value of cervical fetal fibronectin detection by a quantitative enzyme-linked immunosorbent assay as a predictor of preterm delivery in a population (n = 111) of middle-class pregnant women considered to be at low risk for preterm delivery.

STUDY DESIGN

In this prospective study, fetal fibronectin samples from cervicovaginal secretions were obtained biweekly from 24 to 34 weeks' gestation.

RESULTS

Twenty-two (20%) patients had at least one positive fetal fibronectin test result. Eleven women (10%) were delivered spontaneously at < 37 weeks; seven of these had at least one positive fetal fibronectin test result (positive predictive value = 31.8%, sensitivity = 63.6). An additional three women were delivered prematurely because of other obstetric indications, and all had negative fetal fibronectin test results. The remaining 15 patients with at least one positive fetal fibronectin test result were delivered at term (> or = 37 weeks). Of the seven women with positive fetal fibronectin results who were delivered prematurely, five were delivered within 2 weeks of obtaining a positive result. However, there were no obvious clinical discriminators between true-positive and false-positive fetal fibronectin results. Eighty-nine women tested negative, and 85 of these women were delivered at term (specificity = 82.0%). The negative predictive value of fetal fibronectin as a predictor of term delivery in this low-risk population is 96.6%, with odds ratio = 8.8 (95% confidence interval 1.9 to 40.3), relative risk = 6.9 (95% confidence interval 1.8 to 26.6), and Fisher Exact Test p = 0.007.

CONCLUSIONS

Although negative biweekly fetal fibronectin determinations for prediction of preterm delivery in this low-risk obstetric population correlate well with the absence of preterm delivery, they are of limited clinical value for the prediction of preterm birth.

Elevation of amniotic fluid interleukin-4 concentrations in women with preterm labor and chorioamnionitis

Preterm labor associated with intrauterine infection is characterized by increased amniotic fluid concentrations of various proinflammatory cytokines, including interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), IL-6, IL-8, and macrophage inflammatory protein-1alpha (MIP-1alpha). The purpose of this study was to determine if preterm labor in women with clinically evident chorioamnionitis is marked by elevations of the anti-inflammatory cytokine interleukin-4 (IL-4) and the T cell growth factor IL-2. Amniotic fluid samples were obtained from (1) women at term, not in labor (n = 10); (2) women at term, in labor (n = 10); (3) women with preterm contractions but undelivered within 1 week of amniotic fluid collection (n = 10); (4) women with preterm labor and delivery without clinically evident chorioamnionitis (n = 10); (5) women with preterm labor associated with chorioamnionitis (n = 8); and (6) women with preterm labor and delivery without infection matched with patients with chorioamnionitis (n = 8). Amniotic fluid concentrations of IL-4 and IL-2 were determined for each sample with a specific and sensitive enzyme-linked immunoassay. We found that women with infection-associated preterm labor and delivery had significantly higher concentrations of IL-4 when compared to appropriately matched controls (p < 0.05). Additionally, women with preterm labor and delivery not associated with infection had higher amniotic fluid IL-4 concentrations than women with preterm contractions but no labor (p < 0.05). Women with term labor had rare modest elevations of amniotic fluid IL-4. No IL-2 was detected in any sample. Our data indicate that amniotic fluid IL-4 is elevated in women with preterm labor and delivery, particularly in association with chorioamnionitis. We suggest that IL-4, although previously considered an anti-inflammatory agent, may have a paradoxical proinflammatory role in the pathogenesis of infection-associated preterm labor.

Elevations of serum interleukin-12 concentrations in women with severe pre-eclampsia and HELLP syndrome

The objective is to test the hypothesis that serum IL-12 concentrations would be elevated in women with severe pre-eclampsia and HELLP syndrome. The Methods used were as follows: Serum was obtained from women admitted to our Labor and Delivery unit diagnosed with severe pre-eclampsia or HELLP syndrome and normal control patients. IL-12 concentrations in these samples were determined by the use of two different and specific enzyme-linked immunosorbent assays for the p40 subunit and the intact p75 dimer. It was found that serum IL-12 (p40 subunit) concentrations were elevated in women with both severe pre-eclampsia (p = 0.011) or HELLP syndrome (= 0.004). Similar findings were noted for these patients when matched with control patients for maternal age, gestational age, and parity. Eleven women had elevations of serum IL-12 p75 dimer, and 10 of these 11 patients had severe pre-eclampsia or HELLP syndrome. In conclusion, we found that women with severe pre-eclampsia and HELLP syndrome commonly have detectable concentrations of the IL-12 p40 monomer and were more likely than normal control women to have detectable serum IL-12 p75 dimer. While the exact role of IL-12 in hypertensive disease during pregnancy is unclear, our data support the hypothesis that the regulation of IL-12 production and metabolism is abnormal in women with pre-eclampsia and HELLP syndrome, perhaps contributing to the immunologic alterations characteristic of these disorders.

Factors related to perineal trauma in childbirth

We conducted an observational cohort study in three nurse-midwifery services to identify patient characteristics and clinical care measures related to perineal trauma at birth. Data were collected on all women who began care with a nurse-midwife in labor, using an adaptation of the Nurse-Midwifery Clinical Data Set (n = 3,049). Study variables included demographics, perineal management techniques and position for birth, and other intrapartum care and events. Univariate and multivariate analyses showed that episiotomy was strongly related to fetal bradycardia, prolonged second stage, ethnic status, and maternal education level. Warm compresses and flexion/counter-pressure to slow delivery were protective. Spontaneous lacerations were influenced by these factors as well. The lateral position for birth was protective, and use of oils or lubricants and the lithotomy position increased lacerations, Multisite studies in nurse-midwifery practices may provide an ideal means of determining effective care measures in healthy populations.

Amniotic fluid epidermal growth factor levels in normal and abnormal pregnancies

OBJECTIVE

To determine the concentrations of epidermal growth factor (EGF) in amniotic fluid (AF) from women during late pregnancy, with and without pathophysiologic complications.

METHODS

All AFs were collected by amniocentesis from the following groups: gestational age at least 38 weeks (n = 15); gestational age 36-37 weeks (n = 10); gestational age 35 weeks (n = 5); labor 34 weeks or less, delivered within 7 days (n = 10); labor 34 weeks or less, undelivered (n = 10); chorioamnionitis (n = 7); gestational age-matched controls (n = 7); term, in labor (n = 8); term, not in labor (n = 8); intrauterine growth restriction (IUGR) 38 weeks or more (n = 8); macrosomia at 38 weeks or more (n = 10). Epidermal growth factor was assayed using a specific radioimmunoassay.

RESULTS

Amniotic fluid EGF levels increase rapidly in late pregnancy but are not altered by chorioamnionitis or by term or preterm labor. Intrauterine growth restriction is associated with lower EGF levels in AF, but macrosomia is without effect.

CONCLUSIONS

Epidermal growth factor levels in AF are increased near term and decreased in pregnancies complicated by IUGR; they may be an indicator of specific maturational events.

Elevations of amniotic fluid macrophage inflammatory protein-1 alpha concentrations in women during term and preterm labor

OBJECTIVE

To determine whether elevated concentrations of macrophage inflammatory protein-1 alpha (MIP-1 alpha) in amniotic fluid (AF) are related to term and preterm labor.

METHODS

Amniotic fluid was obtained from women from five different clinical situations: 1) term cesarean delivery, no labor (n = 29); 2) normal term labor, no infection (n = 36); 3) preterm labor, delivery more than 1 week from sampling, no infection (n = 19); 4) preterm labor, delivery within 1 week from sampling, no infection (n = 18); and 5) preterm chorioamnionitis (n = 8). Amniotic fluid was collected aseptically at the time of amniocentesis, amniotomy, or hysterotomy. Concentrations of MIP-1 alpha were determined by enzyme-linked immunosorbent assay. Statistical analysis was by Wilcoxon rank-sum test, Kruskal-Wallis test, and unpaired t test.

RESULTS

Women in normal term labor had significant elevations of AF MIP-1 alpha concentrations when compared with women at term undergoing repeat cesarean delivery (P < .001). In women with term gestation, AF MIP-1 alpha correlated well with cervical dilation (r2 = 0.479, P < .001). In women with preterm labor who later delivered within 1 week of presentation, AF MIP-1 alpha concentrations were higher than those from women who did not deliver within 1 week. Women who presented with clinically evident chorioamnionitis had the highest concentrations of AF MIP-1 alpha (P = .001).

CONCLUSION

Women in labor have significantly elevated AF concentrations of MIP-1 alpha, particularly if labor is associated with intrauterine infection. We suggest that MIP-1 alpha is involved in the physiology of normal labor and in the pathogenesis of infection-associated preterm labor.

Significant decrease in parathyroid hormone-related protein concentrations in amniotic fluid with labour at term but not preterm

It has been determined whether amniotic fluid concentrations of parathyroid hormone-related protein (PTHrP) change with labour. An evaluation of which cells from intrauterine tissues might produce PTHrP has also been conducted. Amniotic fluid was obtained by amniocentesis from women: (1) at term, not in labour; (2) in normal term labour; (3) in preterm labour, undelivered within one week; (4) in preterm labour, delivered within one week; (5) in preterm labour associated with clinical chorioamnionitis; and (6) who were gestation-matched controls for chorioamnionitis patients-women in this group were similar to those in Group 4 but were different patients. Amnion, chorion, and decidual cells were grown by standard techniques and incubated with interleukin-1 beta (IL-1 beta). PTHrP was assayed in duplicate samples of amniotic fluid or tissue culture media using an immunoradiometric assay. There was a significant reduction in amniotic fluid concentrations of PTHrP during labour at term. Preterm labour was not associated with significant changes in amniotic fluid concentrations of PTHrP although a trend for reduced concentrations was observed. Amnion and chorion produced measurable quantities of PTHrP and rates of production were increased by treatment with IL-1 beta. Decidual cells did not produce detectable amounts of PTHrP. Hence, labour at term is associated with a decrease in amniotic fluid PTHrP concentrations that may reflect reduced amnion production, which in turn may play a permissive or active role in the mechanism(s) of parturition. These data support the view that the mechanisms that control term and preterm labour may be regulated differently.

Expression of Drosophila lamin C is developmentally regulated: analogies with vertebrate A-type lamins

Vertebrate nuclear lamins form a multigene family with developmentally controlled expression. In contrast, invertebrates have long been thought to contain only a single lamin, which in Drosophila is the well-characterized lamin Dm0. Recently, however, a Drosophila cDNA clone (pG-IF) has been identified that codes for an intermediate filament protein which harbors a nuclear localization signal but lacks a carboxy-terminal CAAX motif. Based on these data the putative protein encoded by pG-IF was tentatively called Drosophila lamin C. To address whether the pG-IF encoded protein is expressed and whether it encodes a cytoplasmic intermediate filament protein or a nuclear lamin we raised antibodies against the recombinant pG-IF protein. The antibodies decorate the nuclear envelope in Drosophila Kc tissue culture cells as well as in salivary and accessory glands demonstrating that pG-IF encodes a nuclear lamin (lamin C). Antibody decoration, in situ hybridization, western and northern blotting studies show that lamin C is acquired late in embryogenesis. In contrast, lamin Dm0 is constitutively expressed. Lamin C is first detected in late stage 12 embryos in oenocytes, hindgut and posterior spiracles and subsequently also in other differentiated tissues. In third instar larvae lamins C and Dm0 are coexpressed in all tissues tested. Thus, Drosophila has two lamins: lamin Dm0, containing a CaaX motif, is expressed throughout, while lamin C, lacking a CaaX motif, is expressed only later in development. Expression of Drosophila lamin C is similar to that of vertebrate lamin A (plus C), which loses its CaaX motif during incorporation into the lamina.

Cognitive function, thyroid status and postpartum depression

Impairment of cognitive function can occur with thyroid disorder and also with depression. Since depression occurs in conjunction with postpartum autoimmune thyroiditis, the question arises as to whether any impairment of cognitive function in postpartum women is related to change in thyroid status or to depressed mood. A total of 242 women (110 thyroid antibody-positive and 132 antibody-negative) were assessed at 8, 12, 20 and 28 weeks postpartum in the outpatients of a district general hospital. Thyroid antibody levels (antimicrosomal and antithyroglobulin) were monitored at monthly intervals, together with plasma T3, T4 and thyroid-stimulating hormone. The main outcome measures were Research Diagnostic Criteria for depression, the 17-item Hamilton Depression Rating Scale and the Edinburgh Postnatal Depression Scale, together with reaction time and digit span. Subjects with postnatal depression showed detectable cognitive impairment independent of thyroid antibody status and actual thyroid dysfunction.

Clinical value of amniotic fluid interleukin-6 determinations in the management of preterm labour

OBJECTIVE

To ascertain whether the determination of amniotic fluid interleukin-6 (IL-6) concentrations would be a useful clinical test in the management of women with preterm contractions.

SETTING

The labour and delivery unit and the Fetal Diagnostic Centre at the University of Utah.

SUBJECTS

Pregnant women at various stages of gestation in the third trimester.

DESIGN

Amniotic fluid samples were collected from women experiencing one of four clinical scenarios: 1. term pregnancy, not in labour with no evidence of intrauterine infection; 2. normal term labour with no evidence of infection; 3. preterm labour with no evidence of infection and undelivered within one week of sampling; and 4. preterm labour and delivered within seven days of sample collection. Amniotic fluid was obtained by amniocentesis or at the time of amniotomy or hysterotomy. IL-6 in each specimen was determined by a specific rapid ELISA.

RESULTS

Amniotic fluid IL-6 levels, given as mean (SEM) in the four groups of women listed were: 1. term pregnancy, not in labour: 20.9 (7.2) pg/ml (n = 60); 2. normal term labour with no infection: 554 (90.7) pg/ml (n = 46); 3. preterm labour with no evidence of infection, undelivered: 47.0 (17.2) pg/ml (n = 35); and 4. preterm labour, delivered: 456.7 (101.7) pg/ml (n = 40). There was no significant difference in the means of amniotic fluid IL-6 for the term labour and preterm labour delivered groups. In general, amniotic fluid IL-6 levels during term labour increased with advancing cervical dilation. There was no correlation of cervical dilation and amniotic fluid IL-6 levels in women having preterm delivery. Receiver-operator curves revealed optimal IL-6 levels for discrimination of labour at term to be 50 pg/ml and for preterm delivery to be 200 pg/ml.

CONCLUSIONS

IL-6 can readily be detected in the amniotic fluid of most women who are in active labour, regardless of gestational age. Our data suggest that amniotic fluid IL-6 determinations may be clinically useful in the management of preterm labour.

Expression of AMPA-selective glutamate receptor subunits in morphologically defined neurons of the mammalian cochlear nucleus

Glutamate and related amino acids mediate fast excitatory neurotransmission in the vertebrate CNS via ligand-gated cationic channels in the neuronal membrane. These channels are composed of different subunits that assemble into a functional receptor/channel complex. Although studies have shown that these subunits are differentially expressed in neurons, few studies have quantitatively addressed the cell-specific expression of glutamate subunits in relation to known glutamatergic pathways. In the vertebrate auditory system, glutamate is the proposed neurotransmitter of the auditory nerve and parallel fiber pathways. In situ hybridization histochemistry was used to localize AMPA-selective glutamate receptor subunit mRNAs in seven cell types of the rat cochlear nucleus. GluR1-GluR4 AMPA-selective subunits were all expressed in cochlear nucleus neurons; however, the subunits expressed in identified cells varied with the cell type. Granule cells, previously not known to receive glutamatergic input, expressed GluR2 and GluR4 subunits. Cartwheel and stellate interneurons in the dorsal cochlear nucleus, which receive parallel fiber input, expressed all four subunits. Neurons receiving synaptic input from the auditory nerve, including globular, round, spherical, and fusiform cells, expressed GluR2, GluR3, and GluR4 subunits. Furthermore, a subpopulation of round cells in the ventral cochlear nucleus, and fusiform cells in the dorsal cochlear nucleus, expressed the GluR3 subunit at greatly reduced levels compared to neighboring cells. The results confirm the auditory nerve and parallel fiber pathways as glutamatergic and identify a third synaptic population, projecting to granule cells, which is likely glutamatergic. The data suggest that the composition of GluR1-GluR4 subunits on neurons in the cochlear nucleus may be related to presynaptic input; moreover, heterogeneous patterns of expression of the GluR3 subunit, in addition, suggest that variability in mRNA levels within one population of morphologically defined cells is present.

Neurotransmission in the auditory system

Neurotransmitters and neuromodulators thought to be active on neurons in the cochlea, CN, and SOC have been reviewed. The variety of neurotransmitters and neuromodulators present and likely colocalized in these neurons are the chemical substrates that link morphologically and physiologically diverse neurons to process sound information. The impact of the limited number of neurotransmitters and neuromodulators in the auditory system is magnified by their interaction with structurally diverse receptors; thus great functional diversity is possible. Moreover, the effects of neurotransmitters and neuromodulators are not limited to synaptic transmission but serve as trophic agents for the establishment of neuronal circuitry during development and the rearrangement of synapses as a result of sensory experience or injury. An understanding of the neurochemical aspects of sensory processing at these diverse synapses then is of fundamental importance in understanding the organization of the auditory system.

Solubilization and purification of an alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid binding protein from bovine brain

alpha-Amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) is a selective ligand for an excitatory amino acid receptor subtype in mammalian brain. We have solubilized an AMPA binding protein from bovine brain membranes with 1% Triton X-100 in 0.5 M phosphate buffer and 20% glycerol at 37 degrees C and purified the stable binding sites using a series of chromatographic steps. Scatchard analysis of the purified preparation showed a curvilinear plot with dissociation constants of 10.6 and 323 nM and Bmax values of 670 and 1,073 pmol/mg of protein for the high- and low-affinity sites, respectively. Inhibition constants for several excitatory amino acid analogues were similar to those obtained for other membrane and solubilized preparations. Gel filtration of the soluble AMPA binding protein showed a single peak of [3H]AMPA binding activity at Mr approximately 500,000. With sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the purified AMPA binding protein showed a single major band at Mr = 110,000. Previously, we have shown that a monoclonal antibody (KAR-B1) against a frog brain kainate binding protein selectively recognizes an unknown protein in mammalian brain migrating at Mr approximately 100,000. We now show that this antibody recognizes the major component of the purified AMPA binding protein, supporting a structural similarity between the frog brain kainate binding protein and the mammalian AMPA binding protein.

Structural characterization and expression of a brain specific gene encoding chick kainate binding protein

The gene encoding chick kainate-binding protein (c-KBP), a member of the non-NMDA ionotropic glutamate receptor family has been isolated and characterized. The c-KBP gene is at least 13 kilobases long and contains 11 exons interrupted by 10 introns. Primer extension and RNase protection studies identified a major transcription initiation site located 117 bases upstream from the initiation methionine codon ATG. Consensus TATA and CCAAT sequences were detected in the putative promoter region. The structure of the c-KBP gene is strikingly different from that of other members of neurotransmitter-gated ion-channels (cloned at present) although the topology of c-KBP consists of four membrane-spanning domains, a structural characteristic of ionotropic receptor subunits. The c-KBP gene was found to be expressed at high levels in chick cerebellar Bergmann glia and at extremely low levels in the forebrain. The limited expression of the c-KBP gene raises important questions concerning the mechanisms governing the regulation of c-KBP gene transcription.

Knowledge retention and clinical application after continuing education

The authors investigate the knowledge retention and clinical application of physical assessment skills by nurses who participated in a required continuing education workshop. Tools were developed to measure the specific application of workshop concepts. Results support the underlying objectives of nursing staff development, which are to increase knowledge and improve skills.

Differential expression of two distinct forms of mRNA encoding members of a dipeptidyl aminopeptidase family

We have identified two cDNAs encoding dipeptidyl aminopeptidase-like proteins (DPPXs) in both bovine and rat brains that have different N-terminal cytoplasmic domains but share an identical transmembrane domain and a long C-terminal extracellular domain. In both species, one of the cDNAs encodes a protein (designated DPPX-S) of 803 amino acid residues with a short cytoplasmic domain of 32 amino acids, and the other cDNA encodes a protein (designated DPPX-L) with a longer cytoplasmic domain--the bovine cDNA encodes 92 amino acids and the rat cDNA encodes 88 amino acids. The membrane topology of DPPX-S and -L is similar to that of other transmembrane peptidases, and DPPX-S share approximately 30% identity and 50% similarity with reported yeast and rat liver dipeptidyl aminopeptidase amino acid sequences, suggesting that DPPX is a member of the dipeptidyl aminopeptidase family. DPPX-S mRNA is expressed in brain and some peripheral tissues including kidney, ovary, and testis; in contrast, DPPX-L mRNA is expressed almost exclusively in brain. No transcripts for either form are found in heart, liver, or spleen. In situ hybridization studies show that the two transcripts have different distributions in the brain. DPPX-L mRNA is expressed in limited regions of brain with the highest level of expression in the medial habenula. More widespread expression is seen for DPPX-S mRNA. The differential distribution of mRNAs for the DPPX-S and -L suggests that these proteins are involved in the metabolism of certain localized peptides and that the cytoplasmic domain may play a key role in determining the physiological specificity of DPPX.

Current issues in occupational health nursing. A Canadian perspective

The National Association of Occupational Health Nurses is still in its infancy and is striving to become an interest group under the umbrella of the Canadian Nurses Association. This will bring together the provincial associations in a common goal of promoting worker health and safety. The diversity of the country and the sheer magnitude of the various occupations of Canadians reflect the need for the occupational health nurse to be well educated and kept abreast of new developments. Changes in the worksite echo changes in health and safety legislation that will help to improve conditions in the workplace. Future challenges arise from changes in the work force and the nature of work and include: ergonomic issues, job stress, older workers, EAPs, and increased competition.

Antibodies to a C-terminal peptide of the rat brain glutamate receptor subunit, GluR-A, recognize a subpopulation of AMPA binding sites but not kainate sites

Antibodies were made to a thirteen amino acid synthetic peptide corresponding to the C-terminal portion of the glutamate (glu) receptor, GluR-A. The immunoprecipitation of kainic acid (KA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) binding sites by the anti-peptide antibodies was studied using a detergent-solubilized preparation of rat brain membranes. Under these conditions a subpopulation of AMPA binding sites was recognized by the antibodies, but no KA binding sites were recognized. Scatchard analysis of this subpopulation of AMPA binding sites yields a curvilinear plot which fits a two-site model with dissociation constants of 4.6 and 323 nM. These studies show that the glu receptor complex, GluR-A, binds AMPA but not KA and suggest that (i) the binding sites for these two ligands reside on different proteins, and (ii) the KA receptor identified physiologically is not equivalent to the KA binding sites identified with 3H-labelled KA.