Performances and limits of Bag-Valve-Device for pre-oxygenation and manual ventilation: A comparative bench and cadaver study.

INTRODUCTION: Bag-Valve-Device (BVD) is the most frequently used device for pre-oxygenation and ventilation during cardiopulmonary resuscitation (CPR). A minimal expired fraction of oxygen (FeO2) above 0.85 is recommended during pre-oxygenation while insufflated volume (VTi) should be reduced during manual ventilation. The objective was to compare the performances of different BVD in simulated conditions. METHODS: Nine BVD were evaluated during pre-oxygenation: spontaneous breathing patients were simulated on a test lung (mild and severe conditions). FeO2 was measured with and without positive end-expiratory pressure (PEEP). CO2 rebreathing was evaluated. Then, manual ventilation was performed by 36 caregivers (n = 36) from three hospitals on a specific manikin; same procedure was repeated by 3 caregivers (n = 3) on two human cadavers with three of the nine BVD: In non-CPR scenario and during mechanical CPR with Interrupted Chest Compressions strategy (30:2). RESULTS: Pre-oxygenation: FeO2 was lower than 0.85 for three BVD in severe condition and for two BVD in mild condition. FeO2 was higher than 0.85 in eight of nine BVD with an additional PEEP valve (PEEP 5 cmH2O). One BVD induced CO2 rebreathing. Manual ventilation: For non-CPR manual ventilation, mean VTi was within the predefined lung protective range (4-8 mL/kg PBW) for all BVD on the bench. For CPR manual ventilation, mean VTi was above the range for three BVD on the bench. Similar results were observed on cadavers. CONCLUSIONS: Several BVD did not reach the FeO2 required during pre-oxygenation. Manual ventilation was significantly less protective in three BVD. These observations are related to the different BVD working principles.

Clinic visits and prescribing patterns among Veterans Affairs Maryland Health Care System dementia patients.

OBJECTIVE: Our objective was to determine how patient demographics and outpatient referrals to specialized dementia (DEM) or mental health (MH) clinics influence receipt of anti-dementia (AD), antidepressant (ADEP), antipsychotic (APSY) and sedative-hypnotic (SEDH) medications among veterans with dementia. DESIGN: Retrospective, cross-sectional observational study. SETTING: Veterans Affairs Maryland Health Care System (VAMHCS). PARTICIPANTS: Veterans aged ≥ 60 years with Alzheimer's or related dementia diagnosis after 1999 with minimum of one-year follow-up or death were included. MEASUREMENTS: Retrospective analysis of VAMHCS electronic medical records were used to determine predictors of AD, ADEP, APSY, and SEDH prescribing using logistic regression models that examined visits to DEM or MH clinics, patient age, follow-up time, race/ethnicity and marital status. RESULTS: Among 1209 veterans with average follow-up of 3.2 (SD 1.9) years, 36% percent had MH visits, 38% had DEM visits and 19% visited both clinics. DEM visits were associated with AD and ADEP but not APSY medication receipt (OR(AD:DEM) = 1.47, 95% CI = (1.052, 2.051); OR(ADEP:DEM) = 1.66, 95% CI = (1.193, 2.302); OR(APSY:DEM) = 1.35, 95% CI = (0.941, 1.929)). MH visit was associated with ADEP and APSY medication receipt (OR(AD:MH)\ = 1.16, 95% CI = (0.821, 1.631); OR(ADEP:MH) = 2.83, 95% CI = (2.005, 4.005); OR (APSY:MH) = 4.41, 95% CI = (3.109, 6.255)). CONCLUSION: In the VAMHCS dementia population, visits to DEM or MH specialty clinics increase the odds of receiving AD, ADEP, and APSY medications.

Calreticulin modulates capacitative Ca2+ influx by controlling the extent of inositol 1,4,5-trisphosphate-induced Ca2+ store depletion.

Calreticulin (CRT) is a highly conserved Ca(2+)-binding protein that resides in the lumen of the endoplasmic reticulum (ER). We overexpressed CRT in Xenopus oocytes to determine how it could modulate inositol 1,4,5-trisphosphate (InsP(3))-induced Ca(2+) influx. Under conditions where it did not affect the spatially complex elevations in free cytosolic Ca(2+) concentration ([Ca(2+)](i)) due to InsP(3)-induced Ca(2+) release, overexpressed CRT decreased by 46% the Ca(2+)-gated Cl(-) current due to Ca(2+) influx. Deletion mutants revealed that CRT requires its high capacity Ca(2+)-binding domain to reduce the elevations of [Ca(2+)](i) due to Ca(2+) influx. This functional domain was also required for CRT to attenuate the InsP(3)-induced decline in the free Ca(2+) concentration within the ER lumen ([Ca(2+)](ER)), as monitored with a "chameleon" indicator. Our data suggest that by buffering [Ca(2+)](ER) near resting levels, CRT may prevent InsP(3) from depleting the intracellular stores sufficiently to activate Ca(2+) influx.

The effect of sodium citrate in arterial catheters on acid-base and electrolyte measurements.

OBJECTIVE: To compare the effects of heparin or sodium citrate used to anticoagulate indwelling arterial catheters on acid-base and electrolyte measurements. DESIGN: Randomized controlled trial. SETTING: Medical-surgical university-affiliated intensive care unit. SUBJECTS: Twenty patients with indwelling arterial catheters. INTERVENTIONS: Patients were randomly allocated to have ten 1-mL aliquots of blood sampled serially from an arterial catheter maintained with either heparin or sodium citrate. A sample then obtained by arterial puncture provided true measurement values. Acid-base and electrolyte measurements of whole blood were obtained from each sample by means of a Coming 860 analyzer. MEASUREMENTS AND MAIN RESULTS: Contamination with sodium citrate lowered ionized calcium and pH but increased glucose and Pco2. Heparin produced negligible effects on those measurements. When sodium citrate was used, reliable measurements were not obtained for ionized calcium, pH, and glucose, even after 9 mL of blood had been discarded. However, reliable P(CO2) measurements were obtained after 2 mL of blood was discarded. CONCLUSIONS: Sodium citrate used to maintain arterial catheters can contaminate blood samples. The result of that contamination can mimic severe hypocalcemia, metabolic acidosis, and mild hyperglycemia. Failure to recognize the effects of sodium citrate on acid-base and electrolyte measurements may lead to changes in treatment that could affect patient outcome adversely.

Estimated incidence and prevalence of genital Chlamydia trachomatis infections in the United States, 1996.

BACKGROUND AND OBJECTIVE: Because genital Chlamydia trachomatis infections and their sequelae have a major impact on individuals and the health care system, it is important to periodically update estimates of chlamydia incidence and prevalence in the United States. STUDY DESIGN: Chlamydia incidence and prevalence were estimated using: (1) a method based on estimates of population-specific chlamydia prevalence, and (2) a method based on the chlamydia-to-gonorrhea case rate ratio. RESULTS: Using the prevalence-based method, point prevalence among persons 15 to 44 years of age was estimated to be 1.6 million chlamydial infections, and annual incidence, 2.4 million cases per year. Using a method based on the ratio of reported gonorrhea to chlamydia, incidence was estimated to be 2.8 million infections per year, and prevalence, 1.9 million. Adjustment for sensitivity of diagnostic tests yielded annual incidence estimates of 2.5 to 3.3 million infections. CONCLUSIONS: Using two methods, we estimated the annual incidence of chlamydial infections in the United States among persons 15 to 44 years of age to be approximately 3 million infections. Critical data needed for more precise estimates include: sensitivity of current diagnostics, better data on infections in males, the current extent of underdetection and underreporting, and better data on duration of infection in men and women.

Accelerated Campaign to Enhance STD Services (ACCESS) for youth: successes, challenges, and lessons learned.

BACKGROUND AND OBJECTIVES: Adolescents have the highest sexually transmitted disease (STD) incidence and are often hard to reach with preventive services. Fourteen youth-focused projects were funded by the Centers for Disease Control and Prevention in 1994 through 1995 to pilot innovative, locally relevant, locally acceptable approaches; expand the range and accessibility of services beyond clinic-based facilities; and stimulate increased commitment of local resources. DESIGN: Review and synthesis of 14 youth-focused, innovative projects. RESULTS: Most projects undertook multiple interventions (11/14) in multiple venues (9/14). The majority (9/14) incorporated behavioral interventions, and half offered clinical services in nontraditional settings such as detention facilities, schools, parks, and parking lots. Six projects used peer volunteers; four worked with community coalitions. Most (12/14) obtained local resources. Where assessed, parental support was strong for providing STD prevention services. CONCLUSIONS: These projects increased the access and range of services available to a substantial number of high-risk youth with high STD rates. However, sustaining and scaling-up pilot project activities will be resource intensive. Increased financial and training support to augment evaluation capacity will be critical for innovation to become an integral part of STD prevention programs.

Head-to-head evaluation of five chlamydia tests relative to a quality-assured culture standard.

Nucleic acid amplification tests offer superior sensitivity for the detection of Chlamydia trachomatis infection, but many laboratories still use nonamplification methods because of the lower cost and ease of use. In spite of their availability for more than a decade, few studies have directly compared the nonamplification tests. Such comparisons are still needed in addition to studies that directly compare individual nonamplification and amplification tests. The purpose of this study was to evaluate and compare the performance characteristics relative to culture of five different tests for the detection of C. trachomatis with and without confirmation of positive results. The tests were applied to endocervical specimens from 4,980 women attending family planning clinics in the northwestern United States. The five nonculture tests included Chlamydiazyme (Abbott), MicroTrak direct fluorescent antibody (DFA) (Syva), MicroTrak enzyme immunoassay (EIA) (Syva), Pace 2 (Gen-Probe), and Pathfinder EIA (Sanofi/Kallestad). All positive results obtained with a nonculture test (except MicroTrak DFA) were confirmed by testing the original specimens with a blocking antibody test (Chlamydiazyme), a cytospin DFA (MicroTrak EIA and Pathfinder EIA), and a probe competition assay (Pace 2). The prevalence of culture-proven chlamydia was 3.9%. The sensitivities of the nonculture tests were in a range from 62 to 75%, and significant differences between tests in terms of sensitivity were observed. The positive predictive value for each test was 0.85 or higher. The specificities of the nonculture tests without performance of confirmations were greater than 99%. Performing confirmatory tests eliminated nearly all of the false positives.

Selective screening for chlamydial infection in women: a comparison of three sets of criteria.

Selective screening has been associated with marked declines in the prevalence of chlamydial infection, the most common bacterial sexually transmitted disease (STD) in the United States. A comparison of the performance of different selective screening criteria in three groups of family planning and STD clinic clients shows that criteria recommended by the Centers for Disease Control and Prevention performed well overall, detecting 88-89% of infections by screening 58-74% of women. Criteria based on age alone performed best among low-risk clients with a low prevalence of chlamydial infection, particularly when all women younger than age 25 were screened (sensitivity, 84-92%); the age-based criteria still required screening only 59-71% of all women. Selective screening criteria should be based on age, risk profile and chlamydia prevalence in specific clinical settings, and should be reevaluated as chlamydia prevalence declines.

Adenophostin A can stimulate Ca2+ influx without depleting the inositol 1,4,5-trisphosphate-sensitive Ca2+ stores in the Xenopus oocyte.

Adenophostin A possesses the highest known affinity for the inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) receptor (InsP3R). The compound shares with Ins(1,4,5)P3 those structural elements essential for binding to the InsP3R. However, its adenosine 2'-phosphate moiety has no counterpart in the Ins(1,4,5)P3 molecule. To determine whether its unique structure conferred a distinctive biological activity, we characterized the adenophostin-induced Ca2+ signal in Xenopus oocytes using the Ca2+-gated Cl- current assay. In high concentrations, adenophostin A released Ca2+ from Ins(1,4, 5)P3-sensitive stores and stimulated a Cl- current that depended upon the presence of extracellular Ca2+. We used this Cl- current as a marker of Ca2+ influx. In low concentrations, however, adenophostin A stimulated Ca2+ influx exclusively. In contrast, Ins(1,4,5)P3 and (2-hydroxyethyl)-alpha-D-glucopyranoside 2',3, 4-trisphosphate, an adenophostin A mimic lacking most of the adenosine moiety, always released intracellular Ca2+ before causing Ca2+ influx. Ins(1,4,5)P3 could still release Ca2+ during adenophostin A-induced Ca2+ influx, confirming that the Ins(1,4, 5)P3-sensitive intracellular Ca2+ stores had not been emptied. Adenophostin- and Ins(1,4,5)P3-induced Ca2+ influx were not additive, suggesting that both agonists stimulated a common Ca2+ entry pathway. Heparin, which blocks binding to the InsP3R, prevented adenophostin-induced Ca2+ influx. These data indicate that adenophostin A can stimulate the influx of Ca2+ across the plasma membrane without inevitably emptying the Ins(1,4,5)P3-sensitive intracellular Ca2+ stores.

Performance and cost-effectiveness of selective screening criteria for Chlamydia trachomatis infection in women. Implications for a national Chlamydia control strategy.

BACKGROUND AND OBJECTIVES: Detection of subclinical Chlamydia trachomatis infection in women is a high but costly public health priority. GOALS: To develop and test simple selective screening criteria for chlamydia in women, to assess the contribution of cervicitis to screening criteria, and to evaluate cost-effectiveness of selective versus universal screening. STUDY DESIGN: Cross-sectional study and cost-effectiveness analysis of 11,141 family planning (FP) and 19,884 sexually transmitted diseases (STD) female clients in Washington, Oregon, Alaska, and Idaho who were universally tested for chlamydia using cell culture, direct fluorescent antibody, enzyme immunoassay, or DNA probe. RESULTS: Prevalence of cervical chlamydial infection was 6.6%. Age younger than 20 years, signs of cervicitis, and report of new sex partner, two or more partners, or symptomatic partner were independent predictors of infection. Selective screening criteria consisting of age 20 years or younger or any partner-related risk detected 74% of infections in FP clients and 94% in STD clients, and required testing 53% of FP and 77% of STD clients. Including cervicitis in the screening criteria did not substantially improve their performance. Universal screening was more cost-effective than selective screening at chlamydia prevalences greater than 3.1% in FP clients and greater than 7% in STD clients. CONCLUSIONS: Age and behavioral history are as sensitive in predicting chlamydial infection as criteria that include cervicitis. Cost-effectiveness of selective screening is strongly influenced by the criteria's sensitivity in predicting infection, which was significantly higher in STD clients. At the chlamydia prevalences in the populations studied, it would be cost saving to screen universally in FP clinics and selectively in STD clinics, the reverse of current practice in many locales.

Genital Chlamydia infections in sexually active female adolescents: do we really need to screen everyone?

PURPOSE: To evaluate current Chlamydia trachomatis screening guidelines, which recommend that all sexually active female adolescents undergoing a pelvic examination be tested for chlamydial infection, and determine if instead providers should target particular subpopulations of these adolescents. METHODS: Data were collected from 148,650 sexually active females, ages 15-19 years, tested by direct immunofluorescent antibody in 160 family planning clinics from 1988-92. Trends in chlamydia prevalence by demographic, behavioral, and clinical risk factors were analyzed. Logistic regression modeling was used to identify selective screening criteria. Predictive models were developed for all years combined, as well as for the years when prevalence was highest and lowest. RESULTS: The prevalence of C. trachomatis in this population was 10%, with a 42% decrease (13.2-7.6%) over the 5-year period. Logistic regression identified nine demographic, behavioral, and clinical predictors (p < 0.0001) associated with chlamydial infections. Predictor models from the highest and lowest prevalence years varied little from the combined model. Individual year predictor models showed poor sensitivity and were similar for these 2 years. The screening criteria could not identify a group of adolescents with a prevalence less than 6%. CONCLUSIONS: Several individual risk factors were strongly associated with C. trachomatis, but no single risk factor or combination of risk factors used for selective screening could identify more than 42% of infections in our population. These findings support earlier national recommendations and the need for universal screening of sexually active female adolescents.

Expression of inositol 1,4,5-trisphosphate receptors changes the Ca2+ signal of Xenopus oocytes.

The receptors for the second messenger inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] form a family of closely related proteins that play an important role in regulating the free intracellular Ca2+ concentration. To test the hypothesis that changing the expression level of Ins(1,4,5)P3 receptors could alter the Ins(1,4,5)P3-mediated Ca2+ signal, we overexpressed Ins(1,4,5)P3 receptor type 1 (InsP3R-1) or type 3 (InsP3R-3) in Xenopus laevis oocytes. Expression of InsP3R-1 increased the velocity of the propagating waves of intracellular Ca2+ release but did not affect the Ins(1,4,5)P3-induced entry of extracellular Ca2+ across the plasma membrane. In contrast, expression of intracellular Ca2+ but markedly increased the magnitude and duration of Ca2+ influx. Immunolocalization studied revealed InsP3R-3 at the endoplasmic reticulum, with a relatively stronger signal at or near the plasma membrane. The results suggest that changing the expression level of an InsP3R can alter the Ins(1,4,5)P3-mediated Ca2+ signal and that InsP3R-1 and InsP3R-3 may have different biological functions.

Inositol phosphate structural requisites for Ca2+ influx.

To understand how inositol phosphates (InsP) cause Ca2+ influx, we injected 37 highly purified compounds containing a total of 49 InsP positional isomers into Xenopus oocytes. The eight InsP that stimulated Ca2+ influx were those that had the highest potency at releasing intracellular Ca2+, indicating that their common target was the inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] receptor. To cause Ca2+ influx, these InsP had to be injected in a much higher concentration than the minimal concentration required to release intracellular Ca2+. Such high InsP concentrations could inhibit ongoing oscillatory intracellular Ca2+ release. In addition, we found that InsPs could not elicit further intracellular Ca2+ release during the course of Ca2+ influx. Our data are consistent with the "capacitative Ca2+ entry" hypothesis, which states that InsP stimulate Ca2+ influx by depleting the InsP-sensitive intracellular Ca2+ store. In this context, we would suggest that to deplete the InsP-sensitive intracellular Ca2+ store, InsP may have to be present in a sufficiently high concentration to override the oscillatory Ca(2+)-refilling mechanisms of the stores.

Changes in either cytosolic or nucleoplasmic inositol 1,4,5-trisphosphate levels can control nuclear Ca2+ concentration.

The free nucleoplasmic Ca2+ concentration ([Ca2+]n) may regulate many nuclear events, such as gene transcription. Since the nucleus may possess the enzymes necessary to generate the second messenger inositol 1,4,5-trisphosphate (Ins(1,4,5)P3), and because the nuclear envelope may enclose an Ins(1,4,5)P3-releasable Ca2+ store, we tested the hypothesis that nuclear and/or cytosolic levels of Ins(1,4,5)P3 can control [Ca2+]n. To assay [Ca2+]n, we measured the fluorescence of the Ca2+ indicator fluo 3 in the nucleus of Xenopus oocytes by confocal microscopy. When we injected Ins(1,4,5)P3 into the cytosol, [Ca2+]n increased. This increase in [Ca2]n still occurred when heparin was present in the nucleus, but was abolished when heparin was present in the cytosol, indicating that cytosolic Ins(1,4,5)P3 levels could control [Ca2+]n. When we injected Ins(1,4,5)P3 directly into the nucleus, [Ca2+]n increased, even when heparin was present in the cytosol, indicating that Ins(1,4,5)P3 could control [Ca2+]n from within the nucleus. These results provide functional evidence for Ins(1,4,5)P3 receptors facing the nucleoplasm and raise the possibility that a phosphoinositide cycle situated at the nuclear membranes can control Ca(2+)-dependent nuclear functions.

Second messenger specificity of the inositol trisphosphate receptor: reappraisal based on novel inositol phosphates.

To further understand how the second messenger D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] interacts with its intracellular receptor, we injected 47 highly purified inositol phosphate (InsP) positional isomers in Xenopus oocytes and compared their potency in releasing intracellular Ca2+. The potency of the Ca(2+)-releasing InsPs spanned four orders of magnitude. Seven compounds, including the novel inositol 1,2,4,5-tetrakisphosphate [D/L-Ins (1,2,4,5)P4] and D/L-Ins(1,4,6)P3, had a very high potency. All of these highly active InsPs shared the following structure: two D-trans-equatorial phosphates (eq-P) and one equatorial hydroxyl (eq-OH) attached to ring carbons D-4, D-5, and D-6 (or to the structurally equivalent D-1, D-6, and D-5 carbons). This permissive structure was not sufficient for Ca2+ release, because it was also found in two inactive compounds, Ins(1,6)P2 and Ins(1,3,6)P3. To be active, InsPs also required the structural equivalent of a D-3 eq-OH and/or a D-1 eq-P. Together, our data reveal how the structure of the InsP molecule affects its ability to release Ca2+.

Isolation, characterization, and localization of the inositol 1,4,5-trisphosphate receptor protein in Xenopus laevis oocytes.

Inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) induces Ca2+ oscillations and waves in Xenopus laevis oocytes. Microsomes from oocytes exhibit high-affinity binding for Ins(1,4,5)P3, and demonstrate Ins(1,4,5)P3-induced Ca2+ release. The Ins(1,4,5)P3 receptor (InsP3R) was purified from oocyte microsomes as a large tetrameric complex and shown to have a monomer molecular mass of 256 kDa, compared with 273 kDa for the brain InsP3R. Binding to the oocyte receptor is highly specific for Ins(1,4,5)P3 and is inhibited by heparin (IC50, 2 micrograms/ml). Immunoblot analysis revealed that an antibody against the C-terminal sequence of the brain receptor recognized the oocyte receptor. These results, in addition to the difference in pattern obtained after limited proteolysis, suggest that the oocyte InsP3R is a new shorter isoform of the mammalian brain type I InsP3R. Immunofluorescence experiments indicated the presence of the InsP3R in the cortical layer and the perinuclear endoplasmic reticulum of the oocyte. However, immunological and biochemical experiments did not reveal the presence of the ryanodine receptor. The presence of an InsP3R and the absence of a ryanodine receptor support the importance of Ins(1,4,5)P3 in Ca2+ handling by oocytes and particularly in the induction of Ca2+ oscillations and waves.

InsP3 and Ins(1,3,4,5)P4 act in synergy to stimulate influx of extracellular Ca2+ in Xenopus oocytes.

To investigate the role of D-myo-inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4] in the regulation of Ca2+ influx, we injected inositol phosphates into Xenopus oocytes and measured Ca(2+)-gated Cl- current to assay intracellular free Ca2+ concentration ([Ca2+]i). To assess Ca2+ influx, we removed extracellular Ca2+ or added the inorganic Ca2+ channel blocker Mn2+ to the extracellular bath and measured the resulting change in Cl- current. Ins(1,3,4,5)P4 did not cause Ca2+ influx when injected alone or when preceded by an injection of Ca2+. In contrast, Ins(1,3,4,5)P4 stimulated Ca2+ influx when injected after the poorly metabolized inositol trisphosphate (InsP3) analogues D-myo-inositol 1,4,5-trisphosphorothioate [Ins(1,4,5)P3S3] or D-myo-inositol 2,4,5-trisphosphate [Ins(2,4,5)P3]. These results indicate that Ins(1,3,4,5)P4 is not sufficient to stimulate Ca2+ influx but acts in synergy with InsP3s to cause Ca2+ influx. We also studied the effect of Ca2+ influx on the immediate metabolism of D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] in single oocytes. Ca2+ influx shunted the metabolism of Ins(1,4,5)P3 toward the formation of Ins(1,3,4,5)P4 and away from D-myo-inositol 1,4-bisphosphate [Ins(1,4)P2]. These results suggest that there is a positive feedback regulatory mechanism in which Ca2+ influx stimulates Ins(1,3,4,5)P4 production and Ins(1,3,4,5)P4 stimulates further Ca2+ influx.

STDs and family planning clinics: a regional program for Chlamydia control that works.

PIP: Joint meetings between the members of the US Family Planning Services Program and the STD Program of Region X (comprising Alaska, Idaho, Oregon, and Washington) from fall 1986 through spring 1987 led to the screening and treatment of patients with chlamydia. Samples from patients were sent to state health department laboratories in Idaho, Washington, and Oregon. A direct fluorescent antibody (DFA) slide technique was used to process the cervical smears. Clinic visit record (CVR) information and laboratory results were collected by a central data management company, and sent to CDC and Region X researchers. 6 clinics in 3 of the states collected 2 cervical samples from each of 3000 patients, 1 for smear (DFA slide) and 1 for tissue culture over a 4-month period. During the 1988-1990 period, 136 clinics in the region supplied patient information and test results on over 300,000 samples. Overall, positive rates for chlamydia in the region went from a high of 10.9% in the 1st quarter of 1988 to 6.8% in the last quarter of 1990, with an overall declining trend. This amounted to an almost 37% decrease within the region. When analyzed by state, the positivity rates and decreases were relatively similar: Alaska, 12.2% to 10.0% positivity (18% decrease); Idaho, 10.5% to 8.0% (24% decrease); Oregon, 8.9% to 6.9% (22% decrease); and Washington, 9.3% to 6.6% (29% decrease). In patients 17 years of age and younger, positive rates for chlamydia fell 19%, from 12.2% in 1988 to 9.9% in 1990. In women 18-19 years old and women 20-24 years old, the rates fell 24% and 31%, respectively. Larger decreases in chlamydia rates were found among women in the 25-29 year age group (31% reduction) and in those 30 years old and older (44% reduction). Infection rates decreased in all race/ethnic groups, except Asians. Approximately 2/3 of the women with positive chlamydia tests had no apparent symptoms of disease. Conversely, the presence of certain clinical indicators seemed to correlate with the probability of a positive test result.^ieng

Inositol trisphosphate is required for the propagation of calcium waves in Xenopus oocytes.

Stimuli which act through the second messenger inositol 1,4,5-trisphosphate (InsP3) often increase free intracellular Ca2+ concentration ([Ca2+]i) in a localized subcellular area. Actively propagated Ca2+ waves then extend this focal Ca2+ signal to other parts of the cell. To understand how cells may control the spatial distribution of Ca2+, we investigated the mechanism by which Ca2+ waves propagate through the cytoplasm of Xenopus oocytes. Heparin, which inhibits the binding of InsP3 to its receptor, prevented the migration of Ca2+ waves induced by a poorly metabolized InsP3 (InsP3S3). This result suggested that Ca2+ waves move through the cell via the serial release of Ca2+ from InsP3-sensitive stores. Interventions which caused a localized increase in [Ca2+]i without elevations of InsP3 did not trigger Ca2+ waves. In the presence of a Ins-P3S3, however, endogenously released or locally injected Ca2+ elicited Ca2+ waves. A cooperative interaction between Ca2+ and InsP3 may therefore be responsible for the propagation of Ca2+ waves.