Health measurement instruments and their applicability to military veterans: a systematic review

INTRODUCTION

Accurate measurement of health status is essential to assess veterans' needs and the effects of interventions directed at improving veterans' well-being. We conducted a systematic review to identify instruments that measure subjective health status, considering four components (ie, physical, mental, social or spiritual well-being).

METHODS

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses, we searched CINAHL, MEDLINE, Embase, PsycINFO, Web of Science, JSTOR, ERIC, Social Sciences Abstracts and ProQuest in June 2021 for studies reporting on the development or evaluation of instruments measuring subjective health among outpatient populations. We assessed risk of bias with the Consensus-based Standards for the Selection of Health Measurement Instruments tool and engaged three veteran partners to independently assess the clarity and applicability of identified instruments.

RESULTS

Of 5863 abstracts screened, we identified 45 eligible articles that reported health-related instruments in the following categories: general health (n=19), mental health (n=7), physical health (n=8), social health (n=3) and spiritual health (n=8). We found evidence for adequate internal consistency for 39 instruments (87%) and good test-retest reliability for 24 (53%) instruments. Of these, our veteran partners identified five instruments for the measurement of subjective health (Military to Civilian Questionnaire (M2C-Q), Veterans RAND 36-Item Health Survey (VR-36), Short Form 36, Abbreviated World Health Organization Quality of Life questionnaire (WHOQOL-BREF) and Sleep Health Scale) as clear and very applicable to veterans. Of the two instruments developed and validated among veterans, the 16-item M2C-Q considered most components of health (mental, social and spiritual). Of the three instruments not validated among veterans, only the 26-item WHOQOL-BREF considered all four components of health.

CONCLUSION

We identified 45 health measurement instruments of which, among those reporting adequate psychometric properties and endorsed by our veteran partners, 2 instruments showed the most promise for measurement of subjective health. The M2C-Q, which requires augmentation to capture physical health (eg, the physical component score of the VR-36), and the WHOQOL-BREF, which requires validation among veterans.

Critical care usage after major gastrointestinal and liver surgery: a prospective, multicentre observational study

BACKGROUND

Patient selection for critical care admission must balance patient safety with optimal resource allocation. This study aimed to determine the relationship between critical care admission, and postoperative mortality after abdominal surgery.

METHODS

This prespecified secondary analysis of a multicentre, prospective, observational study included consecutive patients enrolled in the DISCOVER study from UK and Republic of Ireland undergoing major gastrointestinal and liver surgery between October and December 2014. The primary outcome was 30-day mortality. Multivariate logistic regression was used to explore associations between critical care admission (planned and unplanned) and mortality, and inter-centre variation in critical care admission after emergency laparotomy.

RESULTS

Of 4529 patients included, 37.8% (n=1713) underwent planned critical care admissions from theatre. Some 3.1% (n=86/2816) admitted to ward-level care subsequently underwent unplanned critical care admission. Overall 30-day mortality was 2.9% (n=133/4519), and the risk-adjusted association between 30-day mortality and critical care admission was higher in unplanned [odds ratio (OR): 8.65, 95% confidence interval (CI): 3.51-19.97) than planned admissions (OR: 2.32, 95% CI: 1.43-3.85). Some 26.7% of patients (n=1210/4529) underwent emergency laparotomies. After adjustment, 49.3% (95% CI: 46.8-51.9%, P<0.001) were predicted to have planned critical care admissions, with 7% (n=10/145) of centres outside the 95% CI.

CONCLUSIONS

After risk adjustment, no 30-day survival benefit was identified for either planned or unplanned postoperative admissions to critical care within this cohort. This likely represents appropriate admission of the highest-risk patients. Planned admissions in selected, intermediate-risk patients may present a strategy to mitigate the risk of unplanned admission. Substantial inter-centre variation exists in planned critical care admissions after emergency laparotomies.

The effects of morbid obesity on maternal and neonatal health outcomes: a systematic review and meta-analyses

Morbidly obese (Class III, body mass index [BMI] ≥ 40 kg m(-2)) women constitute 8% of reproductive-aged women and are an increasing proportion; however, their pregnancy risks have not yet been well understood. Hence, we performed meta-analyses following the MOOSE (Meta-Analysis of Observational Studies in Epidemiology) guideline, searching Medline and Embase from their inceptions. To examine graded relationships, we compared Class III obesity to Class I and I/II, and separately to normal weight. We found important effects on all three primary outcomes in morbidly obese women: preterm birth <37 weeks was 31% higher compared with Class I (relative risk [RR] 1.31 [1.19, 1.43]) and 20% higher than Class I/II (RR 1.20 [1.13, 1.27]), large-for-gestational age was higher (RR 1.37 [1.29, 1.45] and RR 1.30 [1.24, 1.36] compared with Class I and I/II, respectively), while small-for-gestational age was lower (RR 0.89 [0.84, 0.93] compared with Class I, with nearly identical reductions for Class I/II). Morbidly obese women have higher risks of preterm birth, large-for-gestational age and numerous other adverse maternal and infant health outcomes, relative to not only normal weight but also Class I or I/II obese women. These findings have important implications for screening and care of morbidly obese pregnant women, to try to decrease adverse outcomes.

Using Video Acquired from an Unmanned Aerial Vehicle (UAV) to Measure Fracture Orientation in an Open-Pit Mine

This project explored the feasibility of using video images acquired with an unmanned aerial vehicle (UAV) to obtain three-dimensional (3D) point clouds using structure from motion (SfM) software. Missions were flown using an Aeryon Scout: a lightweight, vertical take-off and landing quadrotor micro UAV with a miniature video camera. The initial mission captured urban scene images that were used to assess system performance while the main mission focused on rock walls where 3D images were used to successfully measure fracture orientations. Point clouds generated from this combination of technologies were sparse, but in the future, improvements in the resolution of original video images would cascade through the processing and improve the overall results. Such a system could have a multitude of applications in the mining industry, contributing to both safety and financial considerations.

Exclusion of Class III malocclusion candidate loci in Brazilian families

The role played by genetic components in the etiology of the Class III phenotype, a class of dental malocclusion, is not yet understood. Regions that may be related to the development of Class III malocclusion have been suggested previously. The aim of this study was to search for genetic linkage with 6 microsatellite markers (D1S234, D4S3038, D6S1689, D7S503, D10S1483, and D19S566), near previously proposed candidate regions for Class III. We performed a two-point parametric linkage analysis for 42 affected individuals from 10 Brazilian families with a positive Class III malocclusion segregation. Analysis of our data indicated that there was no evidence for linkage of any of the 6 microsatellite markers to a Class III locus at = zero, with data supporting exclusion for 5 of the 6 markers evaluated. The present work reinforces that Class III is likely to demonstrate locus heterogeneity, and there is a dependency of the genetic background of the population in linkage studies.

Accuracy of genomic breeding values for residual feed intake in crossbred beef cattle

The benefit of using genomic breeding values (GEBV) in predicting ADG, DMI, and residual feed intake for an admixed population was investigated. Phenotypic data consisting of individual daily feed intake measurements for 721 beef cattle steers tested over 5 yr was available for analysis. The animals used were an admixed population of spring-born steers, progeny of a cross between 3 sire breeds and a composite dam line. Training and validation data sets were defined by randomly splitting the data into training and testing data sets based on sire family so that there was no overlap of sires in the 2 sets. The random split was replicated to obtain 5 separate data sets. Two methods (BayesB and random regression BLUP) were used to estimate marker effects and to define marker panels and ultimately the GEBV. The accuracy of prediction (the correlation between the phenotypes and GEBV) was compared between SNP panels. Accuracy for all traits was low, ranging from 0.223 to 0.479 for marker panels with 200 SNP, and 0.114 to 0.246 for marker panels with 37,959 SNP, depending on the genomic selection method used. This was less than accuracies observed for polygenic EBV accuracies, which ranged from 0.504 to 0.602. The results obtained from this study demonstrate that the utility of genetic markers for genomic prediction of residual feed intake in beef cattle may be suboptimal. Differences in accuracy were observed between sire breeds when the random regression BLUP method was used, which may imply that the correlations obtained by this method were confounded by the ability of the selected SNP to trace breed differences. This may also suggest that prediction equations derived from such an admixed population may be useful only in populations of similar composition. Given the sample size used in this study, there is a need for increased feed intake testing if substantially greater accuracies are to be achieved.

Genetic parameters and genotype x environment interaction for feed efficiency traits in steers fed grower and finisher diets

The objective of this study was to examine the genetic parameters and genetic correlations of feed efficiency traits in steers (n = 490) fed grower or finisher diets in 2 feeding periods. A bivariate model was used to estimate phenotypic and genetic parameters using steers that received the grower and finisher diets in successive feeding periods, whereas a repeated animal model was used to estimate the permanent environmental effects. Genetic correlations between the grower-fed and finisher-fed regimens were 0.50 ± 0.48 and 0.78 ± 0.43 for residual feed intake (RFI) and G:F, respectively. The moderate genetic correlation between the 2 feeding regimens may indicate the presence of a genotype × environment interaction for RFI. Permanent environmental effects (expressed in percentage of phenotypic variance) were detected in the grower-fed steers for ADG (38%), DMI (30%), RFI (18%), and G:F (40%) and also in the finisher-fed steers for ADG (28%), DMI (35%), metabolic mid-weight (23%), and RFI (10%). Heritability estimates were 0.08 ± 0.10 and 0.14 ± 0.15 for the grower-fed steers and 0.42 ± 0.16 and 0.40 ± 17 for the finisher-fed steers for RFI and G:F, respectively. The dependency of the RFI on the feeding regimen may have serious implications when selecting animals in the beef industry. Because of the higher cost of grains, feed efficiency in the feedlot might be overemphasized, whereas efficiency in the cow herd and the backgrounding segments may have less emphasis. These results may also favor the retention (for subsequent breeding) of cows whose steers were efficient in the feedlot sector. Therefore, comprehensive feeding trials may be necessary to provide more insight into the mechanisms surrounding genotype × environment interaction in steers.

Contact damage in an yttria stabilized zirconia: implications

This paper presents the results of a combined experimental and computational study of contact damage in a 3 mole% yttria partially stabilized zirconia (3-YSZ) that is relevant to hip implants and dental restorations. Contact-induced loading in real applications is idealized using Hertzian contact model to explain plasticity phenomena and failure mechanisms observed under monotonic and cyclic loading. Under monotonic loading, the elastic moduli increase with increasing loading levels. Under cyclic loading, the ceramic specimens fail with progressive cone cracking. X-ray analyses reveal that stress-induced phase transformation (from tetragonal to monoclinic phases) occurs under cyclic contact loading above the critical load levels (approximately 8.5 kN). Furthermore, when the cyclic loading level (5.0 kN) is less than a critical load levels (7.5 kN) that is required to induce surface cone cracks, significant plastic damage is observed in the subsurface zone underneath the contact area. These suggest that the cyclic contact loading induce both plastic damage and tetragonalto-monoclinic phase transformation in the 3-YSZ, leading to significant degradation in long-term strength. The implications of the results are discussed for the design of zirconia femoral heads in total hip replacements and zirconia crowns in dental restoration.

Current status and future needs in craniofacial imaging

Imaging is a keystone in understanding and delivery of craniofacial health care. Recent developments in imaging have brought forth many diverse technologies and approaches. This review provides the current status of methods in craniofacial imaging and discusses future needs and directions. New developments in three-dimensional dental and skeletal imaging, as well as three-dimensional facial image acquisition and animation of jaw movement and facial expression are reviewed. Visualization and convergence of the data from these technologies for construction of patient-specific models is described. Insights on how these technologies and approaches could impact research, education as well as the future of craniofacial health care will be discussed.

Three-dimensional visualization of the craniofacial patient: volume segmentation, data integration and animation

The research goal at the Craniofacial Virtual Reality Laboratory of the School of Dentistry in conjunction with the Integrated Media Systems Center, School of Engineering, University of Southern California, is to develop computer methods to accurately visualize patients in three dimensions using advanced imaging and data acquisition devices such as cone-beam computerized tomography (CT) and mandibular motion capture. Data from these devices were integrated for three-dimensional (3D) patient-specific visualization, modeling and animation. Generic methods are in development that can be used with common CT image format (DICOM), mesh format (STL) and motion data (3D position over time). This paper presents preliminary descriptive studies on: 1) segmentation of the lower and upper jaws with two types of CT data--(a) traditional whole head CT data and (b) the new dental Newtom CT; 2) manual integration of accurate 3D tooth crowns with the segmented lower jaw 3D model; 3) realistic patient-specific 3D animation of the lower jaw.

Assessment of pacemaker chronotropic response: implementation of the Wilkoff mathematical model

There are few practical guidelines for proper adjustment of rate responsive pacemaker sensor parameters. This study describes the application of the chronotropic assessment exercise protocol (CAEP) and the Wilkoff model of chronotropic response to assess the adjustment of pacemaker sensor parameters. In 31 patients implanted 1 month previously with a dual sensor pacemaker, pacemaker sensor parameters were adjusted to yield a peak sensor rate of 100 beats/min on a simple 6-minute walk (low intensity treadmill exercise [LITE] protocol); the maximum sensor rate was set to the age predicted maximum heart rate (220-age). The rate response behavior of the pacemaker was then assessed using the slope of metabolic-chronotropic relation (MCR) during CAEP exercise. After adjustments based on the LITE protocol, CAEP exercise yielded MCR slopes of 0.92 +/- 0.25 for the entire study group, which compares well with the predicted normal slope of 1. However, 7 of the 31 patients had sensor MCR slopes during CAEP exercise that were 2 SD or more below expected. To test the sensitivity of this approach to suboptimal pacemaker programming or suboptimal exercise, simulations were performed with the maximum sensor rate programmed below age-predicted maximum heart rate or with exercise truncated before maximum exertion; with these conditions, MCR slopes were sharply lower for the entire group. The authors conclude that a simple treadmill walk (LITE) allowed for optimum programming of sensor parameters in most patients, but in a minority the chronotropic behavior was underresponsive. Failure to appropriately adjust pacemaker maximum sensor rate or failure to achieve peak exercise sharply limits the accuracy of this methodology.

Evaluation of 3-hour ambulation post cardiac catheterization

There is much variation in the length of immobilization for patients post cardiac catheterization. While it is generally agreed that a period of time on bedrest is necessary to prevent post procedural complications, the optimal duration remains unknown. The purpose of this study was to evaluate the effects of 3-hour ambulation post cardiac catheterization with a 7 french (F) arterial catheter on bleeding, hematoma formation, and vascular complications. Retrospective chart data were gathered for a period of 8 months for patients who were on the traditional 5-hour ambulation protocol, and prospective data were gathered for a period of 7 months for patients who received the 3-hour protocol. A total of 880 patients were included in the study, with 472 in the 5-hour ambulation group and 408 in the 3-hour ambulation group. The overall incidence of delayed bleeding and hematoma formation for the 15 month study period was 19.1%, with no occurrence of vascular complications in either group. Patients who received the 3-hour ambulation protocol experienced a significantly lower rate of bleeding and hematoma formation (13%) than patients who received the 5-hour ambulation protocol (24.4%) (p < 0.001). Ambulating patients 3 hours post cardiac catheterization with a 7F catheter was found to be safe, and thus has the potential to decrease hospital length of stay, as well as increase patient comfort.

Flexion contractures of the lower limbs with urogenital anomalies

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Expression of bone microsomal casein kinase II, bone sialoprotein, and osteopontin during the repair of calvarial defects

The temporal expression of bone microsomal casein kinase II, osteopontin, bone sialoprotein, alkaline phosphatase, and the accumulation of a solid calcium-inorganic orthophosphate mineral phase, have been charted from day 2 to day 21 during the repair of calvarial defects in rats induced by the implantation of decalcified rat bone matrix. Unlike the sequence of events that occur when the same decalcified bone matrix is implanted subcutaneously or intramuscularly, in which cases the first tissue to form in response to the implant is cartilage that subsequently calcifies and is later resorbed and replaced by bone, the repair of cranial defects is quite different. In the latter case, the first cells induced are undifferentiated mesenchymal cells and early fibroblasts followed by osteoblastic direct bone formation. Somewhat later a few small islands of cartilage are formed, widely separated and spatially distinct from the newly formed bone matrix. All of the cartilage and most of the implanted decalcified bone matrix are later resorbed and replaced by new bone by day 21. This in vivo model of the repair of a bone defect by direct bone formation has provided an excellent system to follow specific biochemical and physicochemical events. The total accumulation and rate of accumulation of the mineral and the two noncollagenous phosphoproteins (bone sialoprotein and osteopontin), as well as the activities of alkaline phosphatase, and for the first time either in vivo or in cell culture, the activity of microsomal casein kinase II, the major enzyme that phosphorylates the bone phosphoproteins, have been determined as a function of healing time in vivo. The overall general pattern of accumulation of the phosphoproteins and calcium-phosphate mineral phase and their relationships are similar to those reported in osteoblast cell cultures also monitored as a function of time.

Intramedullary nailing versus plate fixation for unstable forearm fractures in children

The purpose of this study was to compare the clinical and radiographic results of plate and screw fixation with intramedullary nailing for unstable fractures of the radius and ulna in children. We proposed that there was a statistically significant difference in the functional outcome and rate of complications between the two groups of patients. A retrospective analysis of 23 patients who were treated with plate-and-screw fixation and 18 who were treated with intramedullary nailing was performed. The average age was 10 years (range, 5-15). Indications for operative treatment included open fractures, irreducible fractures, and unstable fractures. Excellent results were obtained in 78% of patients in both groups at an average of 12 months after surgery. The functional results, rate of union, and rate of complications were statistically similar for the two groups. Intramedullary fixation allows short operative time, excellent cosmesis, minimal soft-tissue dissection, ease of hardware removal, and early motion after nail removal. Intramedullary fixation may provide a useful alternative for treatment of unstable fractures of the radius and ulna.

The catalysis of redox cycling by pyrroloquinoline quinone (PQQ), PQQ derivatives, and isomers and the specificity of inhibitors

Pyrroloquinoline quinone (PQQ) is a widely distributed redox-active cofactor and essential nutrient. For its detection in protein-free ultrafiltrates or dialysates, a highly sensitive amplification assay was developed on the basis of PQQ's ability to catalyze redox cycling at pH 10 in the presence of excess glycine, oxygen, and nitro blue tetrazolium. Herein, we examine the propensities of PQQ, PQQ triester, and its various isomers, and certain PQQ triester derivatives, to catalyze glycine-fueled redox cycling and show that PQQ is the most capable of catalyzing redox cycling. Furthermore, PQQ has a unique pattern of inhibition induced by a series of PQQ antagonists of different potencies. The data indicate that putative PQQ from a biological sample, separated by HPLC and detected by the glycine-fueled redox-cycling assay, can be further identified as PQQ based on the profile of inhibition it displays with the antagonists such as those employed in this study. The methodology presented here should facilitate the specific detection of PQQ in biological samples.

Clinicopathologic correlation of DNA flow cytometric content analysis (DFCA), surgical staging, and estrogen/progesterone receptor status in endometrial adenocarcinoma

DNA flow cytometric content analysis (DFCA) and estrogen (ER) and progesterone (PR) receptor levels are reported to be prognostic with regard to the malignant potential of endometrial adenocarcinoma. We retrospectively reviewed the records of 50 patients presenting with endometrial adenocarcinoma between July 1990 and December 1992, to determine the extent of any pathologic features reported at the time of hysterectomy. Patients whose tumors were nondiploid (aneuploid) by flow cytometry generally presented with a higher pathologic stage, higher grade, and more frequent lymph node involvement. In addition, the majority of clear cell and uterine papillary serous (UPS) adenocarcinoma were also nondiploid. Fourteen of 21 ER-positive tumors aneuploid, as were 18 of 37 PR-positive tumors. We also found DNA-A (DNA content aneuploid) patterns frequently associated with tumor characteristics implicated by other authors as related to aggressiveness. Further studies comparing the molecular biology of tumors to their clinicopathologic features and behavior are needed to fully understand the ultimate malignant potential.

Longitudinal compliance with annual screening for fecal occult blood. Minnesota Colon Cancer Control Study

In a randomized, controlled trial of fecal occult blood screening for colorectal cancer, the Minnesota Colon Cancer Control Study carried out 11 annual mail screens in two phases between 1976 and 1992. This long-term compliance record of 15,476 individuals is summarized and related to demographic characteristics as well as to the screening experience of the participants. There was a strong and consistent effect of age, with peak compliance among participants about 70 years old, and lower compliance among the youngest (< or = 55 years) and oldest (> or = 80 years) participants. There was a significantly higher rate of screen compliance among participants who lived with other participants, compared with households where only one individual participated in the study. Finally, participants who underwent a diagnostic colorectal examination with negative results had significantly lower odds of compliance.

Flow cytometric DNA content analysis of paraffin-embedded tissue derived from cervical carcinoma

PURPOSE

Flow cytometric deoxyribonucleic acid (DNA) content analysis has been shown to be of prognostic importance in some cancers. There have been recent reports of a prognostic importance for DNA content analysis in cervical carcinoma.

METHODS AND MATERIALS

We retrospectively reviewed the hospital and radiation oncology records of cervical carcinoma patients who presented between 1984-1990.

RESULTS

A total of 101 archival paraffin-embedded blocks were processed, of which 77 were of technical quality for analysis. Thirty-five percent were found to be DNA content aneuploid (DNA-A) and 65% DNA content diploid (DNA-D). No statistical difference was found between the two groups in age at diagnosis, % S-phase, coefficient of variation (CV), or proliferative index (PI). A statistical difference was noted in the G2M phase between the two groups (p = 0.004). The median % S-phase was 8.4% in the DNA-D group. A statistical difference (p = 0.017) in survival was noted between the low and high % S-phase DNA-D groups. In patients who received radiation alone, high-PI patients had improved survival compared to low-PI patients. No statistical difference in survival was noted in the high % S-phase DNA-D group and DNA-A group (p = 0.28). Proportional Hazard (Cox) Regression found clinical stage the only independent prognostic indicator for survival.

CONCLUSION

Flow cytometric DNA content analysis is being used more frequently in the management of different malignant tumors. Our study shows that DNA content analysis is useful in determining the prognosis and survival outcomes in cervical carcinomas and may aid in predicting outcome to certain types of treatment regimens.

Characterization of the glycine-dependent redox-cycling activity in animal fluids and tissues using specific inhibitors and activators: evidence for presence of PQQ

Pyrroloquinoline quinone, a redox cofactor first isolated from bacteria, efficiently catalyzes the nonenzymatic oxidation of glycine in the presence of nitroblue tetrazolium. We report that certain metallic cations and heterocyclic aromatic cations, like the N-methyl phenazonium cation and aryl-iodonium compounds, strongly and specifically inhibit this redoxcycling activity. The inhibition by metal cations is reversed by Tiron and that of the aromatic cations by Tiron and thyroxine. These inhibitors and activators affect authentic PQQ and the redox-activity of putative PQQ isolated from biological sources in a similar manner. This indicates that pyrroloquinoline quinone occurs naturally in animal tissues and fluids.

The foot in Apert syndrome

Foot deformity in Apert syndrome is very characteristic and predictable. Progressive synostosis occurs on what is presumably an unsegmented cartilaginous mass. The first ray shortens with medial deviation of the great toe, secondary to growth abnormality and a delta phalanx. The two phalanx digits characteristically go on to fusion, with maintenance of minimal motion at the metatarsal phalangeal joints. The midfoot and hindfoot progress to characteristic fusion in a supinated position. There is prominence of the fifth metatarsal with callosities under the fifth and third metatarsal heads in all patients. Orthotic and surgical management of these conditions is necessary to ensure maximal function in the symptomatic Apert patient.

The effect of repeated mating at short intervals on reproductive performance of gilts

Three trials involving 87 gilts were completed to investigate the role of additional sexual stimulation on various reproductive parameters. Forty-five gilts were mated twice at 12-h intervals at second pubertal estrus with intact boars beginning 12 h after detection of sexual receptivity (control group). Forty-two gilts were exposed to a vasectomized boar 15 min following each fertile mating to provide additional copulatory stimulus (treatment group). This additional exposure improved (P less than .01) conception rate (100 vs 84%). No statistical differences were observed in number of corpora lutea (CL), number of viable embryos (VE) or number of total embryos (TE) at d 30. These results suggest that additional mating stimuli may have a beneficial effect on conception rate. While the use of additional males resulted in more pregnant females, it likely did not have an effect on litter size.

The effect of intrauterine infusions of prostaglandin E2 on luteal function in nonpregnant gilts

Two trials were conducted to study the effects of intrauterine infusions of prostaglandin E2 (PGE2) on luteal function in nonpregnant gilts. Cannulae were surgically implanted on day 9 postestrus into the lumen of each horn with a cephalic vein cannula inserted for collection of peripheral blood. Intrauterine infusions of 0, 25, 75 or 200 microg of PGE2 were initiated at 0900 h on day 12 and administered thereafter every 12 hr until estrus or day 22 in the first trial. The second trial protocol included an increase in the dose of PGE2 administered as well as the frequency of infusion. Infusion of 0, 200, 300 or 400 microg PGE2 was begun at 0300 h on day 12 and continued every 6 hr until estrus or day 22. Cephalic plasma samples for progesterone analysis were collected every six hours from 0300 h on day 11 to 2100 h on day 26 in both trials. In Trial 1 mean plasma progesterone concentrations for all treatments were not different (P>0.05) from the controls on any given day of the estrous cycle. Interestrous interval was unaffected by intrauterine infusion of PGE2. The mean plasma progesterone concentrations for all treatments were not different (P>0.05) from the controls on days 11-18 of the estrous cycle in Trial 2. However, plasma progesterone concentrations for the 200-microg and 300-microg PGE2 groups appeared to be greater than the controls on days 14 and 15, indicating a possible delay in the decline of progesterone for these groups. The mean plasma progesterone concentrations for the treatment groups were lower (P<0.05) than the controls on days 20-26 of the cycle. treatment cycle length did not differ (P>0.05) from previous cycle length; thus treatment with PGE2 had no effect on interestrous interval. PGE2 may have retarded the decline of progesterone secretion by the corpus luteum in some cases, but at these dosages and frequencies of administration PGE2 was ineffective in prolonging luteal maintenance.