Thymidine kinase-deleted vaccinia virus expressing purine nucleoside phosphorylase as a vector for tumor-directed gene therapy

Tumor-directed gene therapy faces many obstacles. Lack of tissue targeting and low in vivo transduction efficiency represent some of the limitations for a successful therapeutic outcome. A thymidine kinase-deleted mutant vaccinia virus has been shown in marker studies to replicate selectively in tumor tissue in animal models. Purine nucleoside phosphorylase (PNP), from E. coli, converts the nontoxic prodrug 6-methylpurine deoxyriboside (6-MPDR) to the toxic purine 6-methylpurine. In this study, we investigated the cytotoxic properties of PNP, expressed by an optimized synthetic early/late promoter in a vaccinia virus (vMPPNP). In vitro cytotoxicity of psoralen-inactivated vMPPNP (1 microg of psoralen, 4 min of LWUV [365 nm]) at the maximum tolerated dose (MTD) of 6-MPDR (80 microM) reduced cell viability by day 3 to 1.7%. At an MOI of 0.002, replication-competent vMPPNP and 6-MPDR (80 microM) caused reduction of cell viability to 19.8% within 4 days. Furthermore, there was complete abrogation of viral replication after intracellular conversion of prodrug into the active toxin. The potency of such a system was similar among all histologies tested. Finally, the cytotoxic efficacy has been shown to be more rapid and complete than that of cytosine deaminase (CD), a more established enzyme/prodrug system. When virus was delivered intraperitoneally into athymic mice with hepatic metastases, followed by administration of prodrug, there was a significant prolongation of survival and a 30% cure rate. In summary, owing to its tumor-targeting capabilities, high transduction efficiency, and high gene expression, a vaccinia virus expressing PNP could prove to be a potent and valuable vector for tumor-targeted gene therapy.

Geographic information systems and public health: mapping the future

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Assessing the impact of Medicaid managed care on TB activities in local health departments

Three in-depth case studies were conducted to explore the impact of Medicaid managed care on local health department prevention activities. Tuberculosis (TB) was selected as a sentinel issue because TB includes both clinical treatment and population-based public health considerations (such as surveillance and contact tracing). Overall, study results indicated that there has been a minimal impact on TB prevention and control services, primarily because few TB patients are served by managed care. However, the sites offer many suggestions for areas to monitor, possible collaborative opportunities, and mechanisms to assure continued TB prevention and control.

A model of the quaternary structure of enolases, based on structural and evolutionary analysis of the octameric enolase from Bacillus subtilis

Purified enolase from Bacillus subtilis has a native mass of approximately 370 kDa. Since B. subtilis enolase was found to have a subunit mass of 46.58 kDa, the quaternary structure of B. subtilis is octameric. The pl for B. subtilis enolase is 6.1, the pH optimum (pHo) for activity is 8.1-8.2, and the Km for 2-PGA is approximately 0.67 mM. Using the dimeric Calpha structure of yeast dimeric enolase as a guide, these dimers were arranged as a tetramer of dimers to simulate the electron microscopy image processing obtained for the octameric enolase purified from Thermotoga maritima. This arrangement allowed identification of helix J of one dimer (residues 86-96) and the loop between helix L and strand 1 (HL-S1 loop) of another dimer as possible subunit interaction regions. Alignment of available enolase amino acid sequences revealed that in 16 there are two tandem glycines at the C-terminal end of helix L and the HL-S1 loop is truncated by 4-6 residues relative to the yeast polypeptide, two structural features absent in enolases known to be dimers. From these arrangements and alignments it is proposed that the GG tandem at the C-terminal end of helix L and truncation of the HL-S1 loop may play a critical role in octamer formation of enolases. Interestingly, the sequence features associated with dimeric quaternary structure are found in three phylogenetically disparate groups, suggesting that the ancestral enolase was an octamer and that the dimeric structure has arisen independently multiple times through evolutionary history.

Augmented capillary leak during isolated hepatic perfusion (IHP) occurs via tumor necrosis factor-independent mechanisms

Isolated organ perfusion of the liver or extremity with tumor necrosis factor (TNF) and melphalan results in regression of bulky tumors in the majority of patients. The efficacy of TNF in this setting is not known, although data suggest that it may exert antitumor effects primarily on tumor-associated neovasculature. We studied the effects of TNF on capillary leak in liver and tumor tissue during isolated hepatic perfusion (IHP) with melphalan. Twenty-seven patients with unresectable cancer confined to the liver underwent a 60-min hyperthermic IHP using 1.5 mg/kg melphalan alone (n = 7) or with 1.0 mg of TNF (n = 20). Complete vascular isolation was confirmed in all patients using an intraoperative leak monitoring I-131 radiolabeled albumin technique. Samples of tumor and liver were collected just prior to and immediately after IHP. There was no difference in I-131 radiolabeled cpm/g of tissue (cpm) in liver versus tumor at baseline (P2 = 0.44). After IHP, I-131 albumin cpm were higher in tumor versus liver (10,999 +/- 1,976 versus 3,821 +/- 780, respectively; P2 < 0.005). However, I-131 albumin cpm in tumor were not effected by TNF (11,636 +/- 2,518 with TNF versus 9,180 +/- 2,674 without TNF; P2 = 0.59). TNF did not affect melphalan concentrations in tumor (1,883 +/- 540 ng/g versus 1,854 +/- 861 ng/g without TNF; P2 = 0.9). Capillary leak, as reflected by diffusion of I-131 radiolabeled albumin into the interstitial space, is comparable in liver and tumor before IHP but is significantly higher in tumor after IHP. The increased diffusion in the capillary tumor bed must occur through TNF-independent mechanisms such as intrinsic features of tumor neovasculature, hyperthermia, or other unrecognized perfusion-related factors. These data indicate that TNF must continue to be critically evaluated in clinical trials before it is routinely used with melphalan in isolated organ perfusion.

Intraarterial calcium stimulation and intraoperative ultrasonography in the localization and resection of insulinomas

BACKGROUND

Standard imaging studies (computed tomography, magnetic resonance imaging, somatostatin receptor scintigraphy, ultrasonography, and angiography) correctly localize insulinomas in less than 50% of patients and provide no information about the feasibility of enucleation based on proximity of tumor to pancreatic duct. We reviewed our experience with intraarterial calcium stimulation (Ca-Stim) and intraoperative ultrasonography (IOUS) to localize and guide management of insulinomas.

METHODS

Thirty-six patients (14 men, 22 women, median age 44 years) with insulinomas were treated between August 1989 and June 1996. Preoperative imaging studies were obtained. Patients underwent abdominal exploration with IOUS. Fourteen were evaluated by a surgeon blinded to preoperative imaging results.

RESULTS

Tumors (4 to 50 mm) were resected by enucleation (67%) or partial pancreatectomy (33%); all were cured. Sensitivities of computed tomography, magnetic resonance imaging, somatostatin receptor scintigraphy, ultrasonography, angiography, and Ca-Stim in localizing insulinomas were 24%, 45%, 17%, 13%, 43%, and 94%, respectively. Tumors were identified by blinded surgical exploration with IOUS in 12 of 14 patients (86%).

CONCLUSIONS

All insulinomas were identified before operation; however sensitivity of individual noninvasive tests was low (less than 50%). In contrast, Ca-Stim was correct in 94% of cases, thus allowing a focused pancreatic exploration and obviating use of blind distal pancreatectomy. IOUS can then be used to guide safe enucleation.

The Foot Function Index for measuring rheumatoid arthritis pain: evaluating side-to-side reliability

The Foot Function Index is a validated and reliable instrument for measuring foot pain, disability, and activity restriction in patients with rheumatoid arthritis. For the purposes of orthopaedic studies in which one foot serves as an internal control, we assessed the side-to-side reliability of the seven-question Foot Function Index pain subscale. Thirty patients with rheumatoid arthritis completed visual analog scale pain questionnaires for both feet on two occasions 8 days apart. Internal reliability of the scale was high, with Cronbach's alphas ranging from 0.94 to 0.96, suggesting good left versus right discriminatory abilities. Principal component factor analysis segregated the questions into two large clusters containing predominantly either left or right foot items. Intraclass correlation coefficients were examined for test-retest reliability (separated by side) and for side-to-side reliability (separated by the day of test). The resultant intraclass correlation coefficients were nearly equivalent, ranging from 0.79 to 0.89. Generalizability analysis yielded similar results. Intraclass correlation coefficients and generalizability analysis demonstrate that the majority of variation is best explained by the differences within subjects or between subjects rather than by test-retest or side-to-side differences. We recommend the Foot Function Index as a reliable measurement scale for use in orthopaedic interventional trials.

Effects of dietary calcium and phosphorus on vitamin D metabolism and calcium absorption in hamster

We studied the following responses to restriction of dietary calcium and phosphorus in the growing hamster: (i) serum concentrations of calcium, inorganic phosphorus, magnesium, and vitamin D metabolites; and (ii) calcium transport by ileum. Diets fed were normal calcium with normal or low phosphorus or low calcium with normal or low phosphorus. We found serum 1 alpha,25-dihydroxycalciferol (1,25-[OH]2D) concentration did not differ significantly among the diet groups. Calcium absorption, measured as serosal/mucosal calcium concentration ratio produced by everted ileal sac, was greater in the low calcium, normal phosphorous group than in all other groups. The other groups did not differ from one another in calcium absorption. Feeding the low calcium, normal phosphorus diet increased inorganic phosphorus and magnesium but decreased calcium concentration in serum in comparison with the three other diets. Both low phosphorus diets were without effect on serum calcium, but the low calcium, low phosphorus diet increased serum inorganic phosphorus and magnesium above that of the normal calcium, low phosphorus diet. Ileal calcium absorption in hamster (i) was independent of serum 1,25-(OH)2D concentration; (ii) increased in response to low dietary calcium if dietary phosphorus was normal; and (iii) was independent of dietary calcium, if dietary phosphorus was low. Despite increased calcium absorption, serum calcium was decreased in the low calcium-normal phosphorus group as compared with all other groups. Feeding low calcium diets increased serum inorganic phosphorus and magnesium as compared with feeding the corresponding normal calcium diets (i.e., independently of whether dietary phosphorus content was normal or low). These studies demonstrate that the interrelationships between calcium absorption and vitamin D and mineral metabolism in hamster differ from other mammals.

Descriptive epidemiology of local public health systems

This article, presented at the Research and Measurement of Public Health Core Functions Science Symposium sponsored by the Centers for Disease Control and Prevention (CDC) in June 1994, provides selected data from the 1992-1993 National Profile of Local Health Departments. The National Association of County and City Health Officials (NACCHO), in cooperation with the CDC Public Health Practice Program Office, recently completed the 1992-1993 National Profile of Local Health Departments. This study describes public health at the local level and updates the first Profile study, conducted in 1989. The study population included 2,888 local health departments (LHDs) in the United States. Responses were received from 72% of LHDs. Comparisons are made with the 1990 Profile where available. This article provides a selected overview of the information contained in the 1992-1993 Profile and includes structure of LHDs, top agency executive, staffing, expenditures, and planning. The findings have important ramifications for community health planners and policy makers at all levels. With the ongoing potential for change in the U.S. health care system, reliable data establishing baselines and monitoring trends in public health at the local level are important. The information in this report, and the 1992-1993 National Profile of Local Health Departments, updates and expands the available knowledge of LHD structures and activities.

Preservation of peristaltic reflex in hypertrophied ileum of guinea pig

Chronic obstruction of the guinea pig ileum leads to distension and muscular hypertrophy, but how this affects passive biomechanical and nerve-mediated contractions and clearance known as peristaltic reflex is unclear. Ileum of controls had a diameter of 3.0 +/- 1.1 mm and a circular muscle thickness of 37.2 +/- 11.2 microns; 4 wk after placement of a nonconstricting Gore-Tex band, the ileum was distended to 10.0 +/- 0.19 mm, and its muscle had hypertrophied to 195.0 +/- 61.2 microns. Hypertrophied segments exceeded controls in capacity (e.g., 5.1 +/- 1.1 vs. 1.1 +/0 0.2 ml at 6 cm), compliance, and hysteresis. Threshold volumes and pressures that triggered the reflex were 3.3 +/- 1.3 ml and 3.1 +/- 0.01 mmHg in hypertrophied vs. 0.7 +/- 0.2 ml and 1.5 +/- 0.2 mmHg in controls. The diameter increase that triggered the reflex was 1.4 +/- 0.1 mm in hypertrophied segments and 0.6 +/- 0.1 mm in controls. Hypertrophied segments generated fewer contractions of virtually double the amplitude and failed to generate a pressure differential between up- and downstream sites as controls did. Hypertrophied segments generated larger stroke volumes and cumulative clearance than controls. The ratio of antegrade to retrograde clearance was similar in hypertrophied and control segments. The length of the occluding segment in hypertrophied preparations exceeded that of controls. Control contractions indented the antimesenteric border and propagated antegrade from their site of origin; bizarre writhing movements of hypertrophied segments made their contractions difficult to monitor. Thus distension and muscular hypertrophy do not interfere with the ability of the chronically obstructed guinea pig ileum to generate a peristaltic reflex at least as readily and as powerful and as effective in clearing the lumen as controls.

Survival of patients with localized prostate cancer treated with percutaneous transperineal placement of radioactive gold seeds: stages A2, B, and C

Between 1984 and 1991, a total of 177 patients with adenocarcinoma of the prostate were treated with transcutaneous, transperineal radioactive gold seeds. Of these 177 patients, 20 were determined to have pelvic lymph node involvement and were excluded from this review. The remaining 157 patients received a median radioactivity dose of 164 mCi with a median follow-up of 48 months. Cancer-specific survival at 5 years was 100% for stage A2 and B1, 90% for stage B2, and 76% for stage C cancer. Covariates of grade, total radioactivity administered, age of the patient, and number of seeds implanted did not influence disease-free survival in a statistically significant manner. Significant complications were observed in two patients. The survival rates of patients treated with 198Au seed implantation for localized cancer are equivalent or better when compared to historical data of patients treated with 125I implantation, external beam radiotherapy, combination radioactive gold seed implantation and external irradiation, and radical prostatectomy. In addition, these comparable survival rates using interstitial 198Au seeds may be achieved with less morbidity.

Discharge instructions: do illustrations help our patients understand them?

STUDY OBJECTIVE

To determine whether the addition of illustrations to discharge instructions improves patient comprehension.

DESIGN

Randomized, blinded, prospective study. A blinded investigator asked a series of questions designed to test the participant's comprehension of the discharge instructions. There were 10 possible correct responses.

SETTING

Emergency department of a rural Level I trauma center.

PARTICIPANTS

Convenience sample of 101 patients discharged with the diagnosis of laceration.

INTERVENTIONS

Patients were randomly assigned to receive discharge instructions with (n = 54) or without (n = 47) illustrations.

RESULTS

The median number of correct responses was five. Patients with illustrations were 1.5 times more likely to choose five or more correct responses than those without illustrations (65% versus 43%; P = .033). The effect of illustrations varied by demographic group. Among nonwhites (n = 51), patients with illustrations were more than twice as likely to choose five or more correct responses (P = .032). Among patients with no more than a high school education (n = 71), patients with illustrations were 1.8 times more likely to choose five or more correct responses (P = .038). Among women (n = 48), patients with illustrations were 1.7 times more likely to chose five or more correct responses (P = .006).

CONCLUSION

The addition of illustrations to discharge instructions for patients who have sustained lacerations improves patient comprehension. There is a large effect among patients who are nonwhite, female, or have no more than a high school education.

Conference attendance: do we meet the new residency review committee requirements?

STUDY OBJECTIVES

To characterize the attendance at and presenters of conferences given to emergency medicine residents and to determine the ability of emergency medicine residents to attend conferences while working in the emergency department and on off-service rotations.

DESIGN

Descriptive study of an anonymous mail survey.

PARTICIPANTS

Residency directors of all approved emergency medicine residency programs in the United States.

RESULTS

Seventy-six of 95 questionnaires (80%) were returned. We defined "high attendance" at emergency medicine conferences as a reported average of at least 75% attendance by emergency medicine resident physicians. Fifty percent of respondents reported high attendance. Conversely, 17% of programs reported poor attendance, which we defined as an average attendance by 50% or fewer emergency medicine resident physicians. Forty-eight percent of programs reported that emergency medicine faculty conducted more than 50% of the conferences, and 16% reported that the faculty conducted 25% or fewer conferences. Ninety-six percent of programs allowed residents to attend conferences during off-service rotations. Ninety-two percent of programs relieved residents of clinical responsibilities during scheduled shifts in the emergency department so that they might attend lectures.

CONCLUSION

We found that a sizable proportion of programs may not have met the new Residency Review Committee requirements for lecture attendance at the time the guidelines were issued. The vast majority of programs met guidelines for relief of clinical duties, and a large proportion of programs exceeded the requirements for percentage of lectures given by emergency medicine faculty.

Subcuticular sutures and the rate of inflammation in noncontaminated wounds

STUDY OBJECTIVE

To determine whether buried, absorbable, subcuticular sutures increase the degree of inflammation in noncontaminated wounds.

DESIGN

Randomized, blinded, prospective trial.

SETTING

Laboratory.

PARTICIPANTS

Eleven Sprague-Dawley rats weighing 300 to 325 g.

INTERVENTIONS

Four wounds were made on each rat. Two wounds on each were closed with three interrupted buried, absorbable, subcuticular sutures 6-0 polyglactin 910 and running 5-0 nylon skin sutures. The other two wounds were closed with running 5-0 nylon skin sutures alone.

RESULTS

Fourteen days after the sutures were placed, the animals were killed, and histologic preparations were made from each wound. Each sample was scored on a scale of 0 to 3 for the presence of inflammatory infiltrates, fibroplasia and capillary proliferation, necrosis, exudates, giant cells, and edema. We determined a total wound score by adding the scores from each category. The mean total wound score was 4.46 +/- 2.92 for those closed with buried, absorbable, subcuticular sutures and 4.91 +/- 2.56 for those closed without buried, absorbable, subcuticular sutures. Using the Wilcoxon rank-sum test, we found no statistically significant difference in mean total wound score of wounds closed with and without buried, absorbable, subcuticular sutures (alpha = .01). The probability of detecting a twofold difference in total wound scores was 60% (beta = .40).

CONCLUSION

Buried, absorbable, subcuticular sutures do not significantly increase the degree of inflammation in noncontaminated wounds.

Physician compliance with advanced cardiac life support guidelines

STUDY OBJECTIVE

To determine compliance with advanced cardiac life support (ACLS) guidelines among ACLS-certified and non-ACLS-certified physicians.

DESIGN

Retrospective review of consecutive cardiac arrests between July 1989 and June 1990, including assessment of the resuscitation leaders' ACLS certification.

SETTING AND PARTICIPANTS

All nontraumatic prehospital and hospital cardiac arrests in a rural university hospital.

RESULTS

Two hundred seven arrests were studied for a total of 436 rhythms with a maximum of 4 rhythms per arrest. There were 78 resuscitations (36.3%) with return of spontaneous circulation. A total of 2,038 interventions were recorded for all rhythms, with 1,320 (64.8%) compliant with ACLS guidelines compared with 718 (35.2%) deviations. Synchronized cardioversion, calcium chloride and sodium bicarbonate were used with significantly higher noncompliance. Ventricular fibrillation had significantly higher mean rhythm deviation scores, whereas scores were significantly lower for sinus rhythm and stable bradycardia (P < .003). Resuscitations led by ACLS-certified and non-ACLS-certified physicians were compared for mean number of deviations per resuscitation attempt, and no differences were found. Resuscitations with return of spontaneous circulation were compared with unsuccessful resuscitations, and there was no difference between groups in controlled deviation scores. No differences could be found between ACLS-certified and non-ACLS-certified physicians for return of spontaneous circulation and survival-to-discharge rates.

CONCLUSION

Despite biannual ACLS training of all medical residents and ICU nurses, noncompliance with ACLS guidelines was noted in 35.2% of treatments. We found no correlation between ACLS certification and ACLS guideline compliance.

Strenuous exercise decreases motility and cross-sectional area of human gastric antrum. A study using ultrasound

Gastric emptying in humans is delayed with strenuous exercise. We used ultrasound imaging in six healthy volunteers to determine whether changes in motility and configuration of the gastric outlet contribute to this delay. After fasting, all individuals ingested chicken broth and garbanzo beans. With subjects sitting upright, transverse and longitudinal real-time views of the gastric antrum were recorded on video tape. In the exercise studies, subjects pedaled an ergometer for 10 min to attain a heart rate of 85% predicted maximum. On a different day, all subjects had an identical study without exercise. The order of performance of exercise and no-exercise studies was randomized. After exercise, contraction frequencies and antral areas were significantly reduced compared to the studies without exercise. In addition, after exercise there was closure of the pylorus and tubular narrowing of the gastric antrum. Closure of the pylorus and decreased gastric antral area and motility may be important in explaining the decrease in gastric emptying that occurs with strenuous exercise.

The association of HLA-B8, B51, DR2, and multiple sclerosis in pars planitis

PURPOSE

To establish a human leukocyte antigen (HLA) association in a homogeneous population of patients with pars planitis.

METHODS

A strict set of inclusion parameters was established for the diagnosis of pars planitis. Forty patients with pars planitis who met these criteria underwent HLA analysis of class I and II phenotypes.

RESULTS

HLA-B8 was present in 15 (37.5%) of 40 patients versus 85 (19.7%) of 431 controls (relative risk, 2.44; P = 0.011). HLA-B51 was present in 9 (22.5%) of 40 patients versus 51 (11.8%) of 431 controls (relative risk, 2.16; P = 0.049). HLA-DR2 was present in 27 (67.5%) of 40 patients versus 121 (28.0%) of 431 controls (relative risk, 5.32; P < 0.0001). HLA-DR2 has been associated with multiple sclerosis (MS). Exclusion of five patients with pars planitis in whom MS subsequently developed did not change the significance of these findings.

CONCLUSIONS

The strongest association of pars planitis with HLA-DR2 and the temporal development of MS in some patients with pars planitis further supports an association between pars planitis and MS.

Retained foreign body: a fingernail fragment?

A 19-year-old female presented four and one-half months after an occupational injury from a punch-type machine. Exploration revealed a large fragment of her fingernail embedded in the fingerpad. Foreign bodies are commonly encountered in the practice of emergency medicine and failure to localize and remove them can result in significant morbidity. We present a case of a fingernail as a foreign body. Foreign bodies may be difficult to detect despite sophisticated imaging techniques. Although not visualized often, a radiolucent foreign body may be inferred from boney changes. A thorough history regarding mechanism of injury and resultant wound exploration are required. When an adequate wound examination using digital tourniquet control and proper precautions is performed, the majority of foreign bodies will be detected.

Long-term speech results of cleft palate patients with primary palatoplasty

This investigation examined the influence of cleft type, type of surgery, age at surgery, and gender on speech proficiency of 204 patients with cleft palate who required only primary palatoplasty. Speech measures were obtained for each subject from at least three annual examinations between the ages of 4 and 16 years. Neither age at surgery nor type of surgery were discriminating factors. The less extensive cleft type, i.e., soft palate only, was associated with greater rates of change in the performance variables than were the other three cleft types. Females showed greater rate changes than males.

Marine trauma, envenomations, and intoxications

When humans encounter marine creatures a variety of maladies may occur, ranging from dermatitis to life-threatening trauma, allergy, envenomations, or intoxications. The emergency physician should be prepared to recognize quickly and address appropriately the potential life threats, which are primarily neurologic, respiratory, and cardiovascular. A high degree of suspicion for these illnesses is needed. Intoxications may be especially confusing. Although most of the syndromes are self-limited and treatment supportive, time is of the essence if neuromuscular paralysis, hypotension, or respiratory compromise is present. Much folklore exists regarding detection and prevention of these entities and should be regarded as such. The last several decades have seen a marked increase in our knowledge base regarding these fascinating envenomations and intoxications. Research in the next several decades probably will produce a variety of diagnostic and therapeutic tools, which will further our understanding of, and ability to specifically manage, these syndromes.

Intraosseous transfusion in an anesthetized swine model using 51Cr-labeled autologous red blood cells

Peripheral venous access can often be difficult to obtain in infants and young children. Landmark articles in the 1940s showed that the intraosseous (IO) route was a viable one for resuscitation. While anecdotal reports and clinical experience suggest that blood products can be transfused via the IO route, it has not been specifically studied nor documented. We performed a prospective study to document the feasibility of red blood cell transfusion via the IO space. We studied the rapid infusion of 51Cr-labeled red blood cells via the IO space through an 18-gauge IO needle in three normovolemic immature swine. Serial central venous samples were removed at 30 seconds and at 1, 5, 15, 30, and 60 minutes and analyzed for evidence of radiolabeling. Our results revealed rapid delivery of radiolabeled red blood cells into the central circulation with no evidence of early heomolysis. Highest counts were seen in samples taken at 30 seconds to 1 minute. We conclude that the IO route is a viable means for blood transfusion in a nonhemorrhagic model.