Nuclear receptor Nr5a2 promotes diverse connective tissue fates in the jaw

Organ development involves the sustained production of diverse cell types with spatiotemporal precision. In the vertebrate jaw, neural-crest-derived progenitors produce not only skeletal tissues but also later-forming tendons and salivary glands. Here we identify the pluripotency factor Nr5a2 as essential for cell-fate decisions in the jaw. In zebrafish and mice, we observe transient expression of Nr5a2 in a subset of mandibular postmigratory neural-crest-derived cells. In zebrafish nr5a2 mutants, nr5a2-expressing cells that would normally form tendons generate excess jaw cartilage. In mice, neural-crest-specific Nr5a2 loss results in analogous skeletal and tendon defects in the jaw and middle ear, as well as salivary gland loss. Single-cell profiling shows that Nr5a2, distinct from its roles in pluripotency, promotes jaw-specific chromatin accessibility and gene expression that is essential for tendon and gland fates. Thus, repurposing of Nr5a2 promotes connective tissue fates to generate the full repertoire of derivatives required for jaw and middle ear function.

Development and maintenance of tendons and ligaments

Tendons and ligaments are fibrous connective tissues vital to the transmission of force and stabilization of the musculoskeletal system. Arising in precise regions of the embryo, tendons and ligaments share many properties and little is known about the molecular differences that differentiate them. Recent studies have revealed heterogeneity and plasticity within tendon and ligament cells, raising questions regarding the developmental mechanisms regulating tendon and ligament identity. Here, we discuss recent findings that contribute to our understanding of the mechanisms that establish and maintain tendon progenitors and their differentiated progeny in the head, trunk and limb. We also review the extent to which these findings are specific to certain anatomical regions and model organisms, and indicate which findings similarly apply to ligaments. Finally, we address current research regarding the cellular lineages that contribute to tendon and ligament repair, and to what extent their regulation is conserved within tendon and ligament development.

FGF signaling patterns cell fate at the interface between tendon and bone

Tendon and bone are attached by a transitional connective tissue that is morphologically graded from tendinous to osseous and develops from bipotent progenitors that co-express scleraxis (Scx) and Sox9 (Scx⁺/Sox9⁺). Scx⁺/Sox9⁺ progenitors have the potential to differentiate into either tenocytes or chondrocytes, yet the developmental mechanism that spatially resolves their bipotency at the tendon-bone interface during embryogenesis remains unknown. Here, we demonstrate that development of Scx⁺/Sox9⁺ progenitors within the mammalian lower jaw requires FGF signaling. We find that loss of Fgfr2 in the mouse tendon-bone interface reduces Scx expression in Scx⁺/Sox9⁺ progenitors and induces their biased differentiation into Sox9⁺ chondrocytes. This expansion of Sox9⁺ chondrocytes, which is concomitant with decreased Notch2-Dll1 signaling, prevents formation of a mixed population of chondrocytes and tenocytes, and instead results in ectopic endochondral bone at tendon-bone attachment units. Our work shows that FGF signaling directs zonal patterning at the boundary between tendon and bone by regulating cell fate decisions through a mechanism that employs Notch signaling.

Nuclear FGFR2 regulates musculoskeletal integration within the developing limb

BACKGROUND

Bent bone dysplasia syndrome (BBDS), a congenital skeletal disorder caused by dominant mutations in fibroblast growth factor receptor 2 (FGFR2), is characterized by bowed long bones within the limbs. We previously showed that the FGFR2 mutations in BBDS enhance nuclear and nucleolar localization of the receptor; however, exactly how shifts in subcellular distribution of FGFR2 affect limb development remained unknown.

RESULTS

Targeted expression of the BBDS mutations in the lateral plate mesoderm of the developing chick induced angulated hindlimbs, a hallmark feature of the disease. Whole-mount analysis of the underlying skeleton revealed bent long bones with shortened bone collars and, in severe cases, dysmorphic epiphyses. Epiphyseal changes were also correlated with joint dislocations and contractures. Histological analysis revealed that bent long bones and joint defects were closely associated with irregularities in skeletal muscle patterning and tendon-to-bone attachment. The spectrum of limb phenotypes induced by the BBDS mutations were recapitulated by targeted expression of wild-type FGFR2 appended with nuclear and nucleolar localization signals.

CONCLUSIONS

Our results indicate that the bent long bones in BBDS arise from disruptions in musculoskeletal integration and that increased nuclear and nucleolar localization of FGFR2 plays a mechanistic role in the disease phenotype. 248:233-246, 2019. © 2018 Wiley Periodicals, Inc.

A requirement for Fgfr2 in middle ear development

The skeletal structure of the mammalian middle ear, which is composed of three endochondral ossicles suspended within a membranous air-filled capsule, plays a critical role in conducting sound. Gene mutations that alter skeletal development in the middle ear result in auditory impairment. Mutations in fibroblast growth factor receptor 2 (FGFR2), an important regulator of endochondral and intramembranous bone formation, cause a spectrum of congenital skeletal disorders featuring conductive hearing loss. Although the middle ear malformations in multiple FGFR2 gain-of-function disorders are clinically characterized, those in the FGFR2 loss-of-function disorder lacrimo-auriculo-dento-digital (LADD) syndrome are relatively undescribed. To better understand conductive hearing loss in LADD, we examined the middle ear skeleton of mice with conditional loss of Fgfr2. We find that decreased auditory function in Fgfr2 mutant mice correlates with hypoplasia of the auditory bulla and ectopic bone growth at sites of tendon/ligament attachment. We show that ectopic bone associated with the intra-articular ligaments of the incudomalleal joint is derived from Scx-expressing cells and preceded by decreased expression of the joint progenitor marker Gdf5. Together, these results identify a role for Fgfr2 in development of the middle ear skeletal tissues and suggest potential causes for conductive hearing loss in LADD syndrome.

Modeling craniofacial and skeletal congenital birth defects to advance therapies

Craniofacial development is an intricate process of patterning, morphogenesis, and growth that involves many tissues within the developing embryo. Genetic misregulation of these processes leads to craniofacial malformations, which comprise over one-third of all congenital birth defects. Significant advances have been made in the clinical management of craniofacial disorders, but currently very few treatments specifically target the underlying molecular causes. Here, we review recent studies in which modeling of craniofacial disorders in primary patient cells, patient-derived induced pluripotent stem cells (iPSCs), and mice have enhanced our understanding of the etiology and pathophysiology of these disorders while also advancing therapeutic avenues for their prevention.

A guide to interpreting economic studies in infectious diseases

Healthcare providers continue to seek improved methods for preventing, detecting and treating diseases that affect human survival and quality of life. At the same time, there will always be financial constraints because of limited societal resources. Many of the discussions on how to provide economically sound solutions to this challenge have not fully engaged the input of clinicians in the field. The purpose of this review is to increase economic knowledge for clinicians. We cover healthcare cost elements and methods used to assign value to a health outcome. We outline the challenges in conducting economic studies in the field of infectious diseases. Finally, we discuss the meaning of efficiency from multiple perspectives, and how the concept of economic externalities applies to infectious diseases.

The role of neural activity in the migration and differentiation of enteric neuron precursors

BACKGROUND

As they migrate through the developing gut, a sub-population of enteric neural crest-derived cells (ENCCs) begins to differentiate into neurons. The early appearance of neurons raises the possibility that electrical activity and neurotransmitter release could influence the migration or differentiation of ENNCs.

METHODS

The appearance of neuronal sub-types in the gut of embryonic mice was examined using immunohistochemistry. The effects of blocking various forms of neural activity on ENCC migration and neuronal differentiation were examined using explants of cultured embryonic gut.

KEY RESULTS

Nerve fibers were present in close apposition to many ENCCs. Commencing at E11.5, neuronal nitric oxide synthase (nNOS), calbindin and IK(Ca) channel immunoreactivities were shown by sub-populations of enteric neurons. In cultured explants of embryonic gut, tetrodotoxin (TTX, an inhibitor of action potential generation), nitro-L-arginine (NOLA, an inhibitor of nitric oxide synthesis) and clotrimazole (an IK(Ca) channel blocker) did not affect the rate of ENCC migration, but tetanus toxin (an inhibitor of SNARE-mediated vesicle fusion) significantly impaired ENCC migration as previously reported. In explants of E11.5 and E12.5 hindgut grown in the presence of TTX or tetanus toxin there was a decrease in the number nNOS+ neurons close to the migratory wavefront, but no significant difference in the proportion of all ENCC that expressed the pan-neuronal marker, Hu.

CONCLUSIONS & INFERENCES

(i) Some enteric neuron sub-types are present very early during the development of the enteric nervous system. (ii) The rate of differentiation of some sub-types of enteric neurons appears to be influenced by TTX- and tetanus toxin-sensitive mechanisms.

The observation unit: a new interface between inpatient and outpatient care

PURPOSE

Observation units for patients who present to emergency departments with chest pain have become common. We describe our 3-year experience with a multipurpose observation unit in which chest pain accounts for only a minority of patients' presenting clinical syndromes.

SUBJECTS AND METHODS

We analyzed the effects of a 12-bed observation unit on inpatient admissions for common clinical syndromes, as well as its overall effects on inpatient medical admissions during its first 3 years of operation (1996 to 1998) compared with the 3 years preceding its creation (1993 to 1995).

RESULTS

Among 7,507 patients admitted to the observation unit in 1996 to 1998, 6,334 (85%) were discharged home within 23 hours. Total inpatient medical admissions fell by a similar number (n = 5,366) during the 3 years of operation of the observation unit when compared with the 3 preceding years (39,569 admissions in 1996 to1998 versus 44,935 in 1993 to 1995). Analysis of local area trends suggested that the use of the observation unit contributed to reduced hospital admissions, rather than vice versa.

CONCLUSION

Observation units can serve patients with diverse clinical syndromes and may reduce inpatient admissions. This novel "point of care" deserves further evaluation.

Determining which patients require evaluation for blunt cardiac injury following blunt chest trauma

The objective of this study was to determine prospectively which risk factors require cardiac monitoring for blunt cardiac injury (BCI) following blunt chest trauma. All patients who sustained blunt chest trauma had an electrocardiogram (ECG) on admission to our urban level I trauma center. Those with ST segment changes, dysrhythmias, hemodynamic instability, history of cardiac disease, age > 55 years, or a need for general anesthesia within 24 hours (group 1) were admitted to the intensive care unit (ICU) for 24 hours where they were subjected to serial ECGs, creatinine phosphokinase (CPK) assays, and echocardiography (ECHO). Those with only mechanism for BCI, i.e., none of the above risk factors (group 2), were admitted to a nonmonitored bed and had a follow-up ECG 24 hours later. A series of 315 patients were admitted with blunt chest trauma during a 17-month period; 144 patients were in group 1 and 171 in group 2. Overall, 22 patients were diagnosed as BCI (+BCI), defined as evolving ST segment changes, dysrhythmias, a CPK-MB index of > 2.5, or hemodynamic instability. Of the 18 +BCI patients in group 1, all were symptomatic (i.e., none was included solely for a cardiac history, age, or need for general anesthesia). Six of these patients required treatment for dysrhythmias, hypotension, or pulmonary edema; one of whom died. Four patients with +BCI were in group 2 and had ECG changes at 24 hours; none of these four had any sequelae from their +BCI. None of the ECHOs demonstrated abnormal wall motion. Patients who sustain blunt chest trauma with a normal ECG, normal blood pressure, and no dysrhythmias on admission require no further intervention for BCI. Patients with ST segment changes, dysrhythmias, or hypotension following blunt chest trauma should be monitored for 24 hours, as this subgroup occasionally requires further treatment for complications of BCI. ECHO adds nothing as a screening test.

Experience with over 2500 diagnostic peritoneal lavages

This study was undertaken to confirm the safety and efficacy of diagnostic peritoneal lavage (DPL) for trauma patients. A prospectively maintained database of all DPLs performed in the past 75 months was analyzed. A red blood cell count of 100,000/mm(3) was considered positive for injury in blunt trauma; 10,000/mm(3) was considered positive for peritoneal penetration in penetrating trauma. Information relative to type of injury, DPL result, laparotomy result and complications, was analysed to determine if DPL was more or less suited to any specific indication or type of patient. Over a 75 month period, 2501 DPLs were performed at our urban level I trauma center. The overall sensitivity, specificity and accuracy for the above thresholds were 95, 99 and 98%. The majority (2409, 96%) were performed using percutaneous or "closed" seldinger technique. Ninety-two (4%) were performed using open technique because of pelvic fractures, previous scars and pregnancy. Open DPL was less sensitive than closed DPL in patients who sustained blunt trauma (90 vs 95%) but slightly more sensitive in determining penetration (100 vs 96%). Overall, there were 21 complications (0.8%). There was no difference in complication rate between open and closed DPL. In conclusion, DPL remains a highly accurate, sensitive and specific test with an extremely low complication rate. It can be performed either open or closed with comparable results. We recommend its use in the evaluation of both blunt and penetrating trauma.

Prognosis of penetrating trauma in elderly patients: a comparison with younger patients

BACKGROUND

It has previously been shown that elderly patients have a worse prognosis than their younger counterparts after sustaining blunt trauma. This is due in part to a higher incidence of comorbid conditions as well as less physiologic reserve in an elderly population sustaining largely blunt trauma. We compared the outcome after penetrating trauma in elderly patients to matched "younger" patients to determine whether they had a similarly poor prognosis.

METHODS

Elderly patients (> or = 65 years) were identified from our trauma registry. Sex, mechanism of injury, and Abbreviated Injury Score/Injury Severity Score were determined from the registry. Patients presenting with traumatic arrest were excluded. The registry was then searched for patients aged 15 to 40 years with the same sex, mechanism of injury, and Abbreviated Injury Score in each region. A chart review was then performed to determine additional details of their hospital stay. The two groups were then compared using Student's t test and Fisher's exact chi2 test, as appropriate.

RESULTS

Eighty-five elderly patients (OLD group) were admitted with penetrating trauma between 1983 and 1998. They were compared with 85 matched young patients (YOUNG group). Each group included 66 male and 19 female patients. In each group, gunshot wounds occurred in 45.9%, stab wounds in 52.9%, and shotgun wounds in 1.2% of patients. The average Injury Severity Score in each group was 5.5 +/- 5.6 (range, 1-29) and the regional Abbreviated Injury Scores were likewise equal in both groups. The OLD patients had an average hospital stay of 6.9 +/- 9.1 days compared with 4.3 +/- 5.7 days in the YOUNG patients (p < 0.05). Twenty-seven OLD patients spent 7.3 +/- 9.2 days in the intensive care unit compared with 19 YOUNG patients who stayed 3.4 +/- 3.2 days (p < .05). A total of 91 comorbidities were identified in 58 OLD patients compared with 18 in 15 YOUNG patients (p < .0001). Eighty-six invasive procedures were performed in the OLD group compared with 96 in the YOUNG group (p = not significant). Nineteen OLD patients (22.3%) and 15 YOUNG patients (17.6%) suffered one or more complications, including death (p = not significant). A total of 91% of surviving OLD patients were discharged to home compared with 100% of surviving YOUNG patients (p < .01).

CONCLUSION

Elderly patients who sustain penetrating trauma have more comorbidities than their younger counterparts. This may account for their longer hospital stay and lesser ability to be discharged home. These patients do not have an increased complication rate and should continue to be managed aggressively.

Enaminones-versatile therapeutic pharmacophores. Further advances

Enaminones, enamines of ss-dicarbonyl compounds, have been know for many years. In our initial account (Current Med. Chem. 1994, 1, 159-175), we reported on the anticonvulsant activity of a series of enaminones, notably methyl 4-[(p-chlorophenyl)amino]-6-methyl-2-oxo-cyclohex-3-en- 1-oate, 9a (R=CH3, R1=4-Cl), which, in animal tests, compared favorably to phenytoin and carbamazepine. Since that time, further research in our laboratory and other laboratories have expanded the therapeutic potential of these compounds. In addition to new anticonvulsant derivatives, we have uncovered a novel brain transport mechanism for the enaminones and developed a preliminary regression model for further synthetic direction. These topics will each be presented and elaborated.

Acidosis and nutrition

In recent years there has been increasing evidence for the deleterious effect of acidosis on a number of fundamental systems of the body including nutrition [1, 2]. Approximately 70 mmol of hydrogen ions are produced daily by the body, and to maintain acid-base balance there must be an equivalent net acid secretion by the kidney. It is remarkable that extracellular fluid (ECF) pH is maintained within a very narrow range of 7.35-7.45 (35-45 nM), reflecting the fundamental importance of pH on many aspects of basic cellular function particularly proteins. It is important to differentiate between the terms acidosis and acidemia. The former is a pathophysiologic process tending to acidify body fluids, whereas the latter occurs when the ECF hydrogen ion concentration is above the normal range. It is possible to be acidotic (with a reduced serum bicarbonate) but not acidemic because of appropriate buffering of hydrogen ions. The major extracellular buffer is the carbonic acid/hydrogen carbonate system with plasma proteins and hemoglobin contributing significantly less. The major intracellular buffer is protein followed by bone [3]. The type of acidosis seen in patients with chronic renal failure changes with decreasing GFR; initially a non-anion gap acidosis is observed secondary to the loss of bicarbonate from the proximal tubule and impaired excretion in the distal tubule. With increasing severity of renal impairment, failure to excrete organic and inorganic acids results in an increased anion gap [4, 5].

Patient satisfaction with an emergency department asthma observation unit

OBJECTIVE

To compare levels of patient satisfaction between the diagnostic and treatment protocols in an ED-based asthma observation unit (AOU) and those with standard inpatient hospitalization.

METHODS

This was a prospective, randomized, controlled trial with a sample of 163 patients presenting to the ED with acute asthma exacerbations over a 30-month period. Eligible patients were those who could not resolve their symptoms after three hours of standard ED therapy. Patients were then randomly assigned to an ED-based AOU (experimental group) or to customary inpatient care (control group). Patient satisfaction and problems with care processes were assessed by standardized instrumentation at discharge in both groups.

RESULTS

The AOU patients scored higher than those randomized to the inpatient hospitalization protocol on four summary ratings of patient satisfaction measures: received service wanted, recommendation of the service to others, satisfaction with the service, and overall satisfaction. The AOU patients reported fewer total number of problems with care received, and fewer specific problems with communication, emotional support, physical comfort, and special needs, than did the inpatient group. However, the AOU patients reported more problems regarding their knowledge of financial costs and liabilities for their service than did the inpatients.

CONCLUSION

Patients were more satisfied and had fewer problems with rapid diagnosis and treatment in the AOU than they did with routine inpatient hospitalization. Since AOUs represent a new ambulatory service modality, patients would benefit from greater awareness of the costs and coverage for AOUs as compared with hospital inpatient care. These findings have important implications for the future short- and long-term success and feasibility of ED-based AOUs.

Distribution of variable vs fixed costs of hospital care

CONTEXT

Most strategies proposed to control the rising cost of health care are aimed at reducing medical resource consumption rates. These approaches may be limited in effectiveness because of the relatively low variable cost of medical care. Variable costs (for medication and supplies) are saved if a facility does not provide a service while fixed costs (for salaried labor, buildings, and equipment) are not saved over the short term when a health care facility reduces service.

OBJECTIVE

To determine the relative variable and fixed costs of inpatient and outpatient care for a large urban public teaching hospital.

DESIGN

Cost analysis.

SETTING

A large urban public teaching hospital.

MAIN OUTCOME MEASURES

All expenditures for the institution during 1993 and for each service were categorized as either variable or fixed. Fixed costs included capital expenditures, employee salaries and benefits, building maintenance, and utilities. Variable costs included health care worker supplies, patient care supplies, diagnostic and therapeutic supplies, and medications.

RESULTS

In 1993, the hospital had nearly 114000 emergency department visits, 40000 hospital admissions, 240000 inpatient days, and more than 500000 outpatient clinic visits. The total budget for 1993 was $429.2 million, of which $360.3 million (84%) was fixed and $68.8 million (16%) was variable. Overall, 31.5% of total costs were for support expenses such as utilities, employee benefits, and housekeeping salaries, and 52.4% included direct costs of salary for service center personnel who provide services to individual patients.

CONCLUSIONS

The majority of cost in providing hospital service is related to buildings, equipment, salaried labor, and overhead, which are fixed over the short term. The high fixed costs emphasize the importance of adjusting fixed costs to patient consumption to maintain efficiency.

The utility of head computed tomography after minimal head injury

OBJECTIVE

To determine if patients who present with a history of loss of consciousness who are neurologically intact (minimal head injury) should be managed with head computed tomography (CT), observation, or both.

METHODS

We prospectively studied patients who presented to our urban Level I trauma center with a history of loss of consciousness after blunt trauma and a Glasgow Coma Scale score of 15. All patients underwent CT of the head and were subsequently admitted for 24 hours of observation.

RESULTS

A total of 1,170 patients with minimal head injury were studied during a 35-month period. All patients had Glasgow Coma Scale scores of 15 on arrival and had a history of either loss of consciousness or amnesia to the event. Two hundred forty-seven patients (21.1%) were intoxicated with drugs or alcohol on admission; 39 patients (3.3%) had abnormalities detected by CT, including 18 intracranial bleeds; 21 patients (1.8%) had changes in therapy as a direct result of their CT results, including 4 operative procedures. No patient with negative CT results deteriorated during the subsequent observation period.

CONCLUSION

CT is a useful test in patients with minimal head injury because it may lead to a change in therapy in a small but significant number of patients. Subsequent hospital observation adds nothing to the CT results and is not necessary in patients with isolated minimal head injury.

Synthesis, characterization, and anticonvulsant activity of enaminones. Part 5: investigations on 3-carboalkoxy-2-methyl-2,3-dihydro-1H-phenothizin-4[10H]-one derivatives

A new series of anticonvulsant 3-carboalkoxy-2-methyl-2,3-dihydro-1H-phenothiazin-4[10H]-on es is herein reported. 2-Aminothiophenols underwent cyclocondensation with 4-carboalkoxy-5-methylcyclohexane-1,3-diones in refluxing dimethylsulfoxide (DMSO) to yield 3-carboalkoxy-2-methyl-2,3-dihydro-1H-phenothiazin-4[10H]-on es, 4ak. In the case of the carbo-tert-butoxy derivatives (4c and 4k) prolonged reaction times led to the isolation of the respective 3-unsubstituted-2-methyl-2,3-dihydro-1H-phenothiazin-4[10H]-ones (41 and 4m) instead. Significant anticonvulsant activity was displayed by these analogues, most particularly 4k, which was active at 30 mg/kg intraperitoneally (ip) in mice in the maximal electroshock seizure (MES) evaluation, with no toxicity noted at dosages up to 300 mg/kg. Oral (p.o.) rat evaluation of 4k in the MES evaluation provided an ED50 of 17.60 mg/kg, with no toxicity noted at dosages up to 500 mg/kg, providing a protective index (PI = TD50/ED50) > 28.40. These compounds represent the first reported series of phenothiazines which possess anticonvulsant activity.

Emergency Department Observation Unit versus hospital inpatient care for a chronic asthmatic population: a randomized trial of health status outcome and cost

OBJECTIVES

This study was designed to determine if an accelerated treatment protocol administered to acute asthmatics presenting to a Hospital Emergency Department Observation Unit (EDOU) can offset the need for inpatient admissions and reduce total cost per episode of care without sacrificing patient quality of life.

METHODS

The authors used a prospective randomized controlled trial comparing postintervention patient quality of life for EDOU care versus standard inpatient care as measured by the standardized Medical Outcomes Study (MOS) SF-36 instrument. Other measures reported include: clinical status as measured by peak flow rates, total cost per treatment arm using microcosting techniques, and relapse-free survival 8 weeks after treatment. Eligible patients (n = 113) were assigned randomly to an EDOU or inpatient care from a consecutive sample of 250 acute asthmatic patients presenting to an urban hospital emergency department who could not resolve their acute asthma exacerbation after 3 hours of emergency department therapy.

RESULTS

Patients assigned to the EDOU had lower mean costs of treatment (EDOU = $1,202 versus Hospital Inpatient = $2,247) and higher quality of life outcomes after intervention in five of eight domains measured by the MOS SF-36: Physical Functioning, Role Functioning-Emotional, Social Functioning, Mental Health, and Vitality. No differences were found in clinical outcomes as measured by peak flow rates or postintervention relapse-free survival. Univariate comparative findings were re-examined and confirmed through multivariable analysis when baseline SF-36 scores and postintervention peak expiratory flow rates clinical status were used as covariates.

CONCLUSIONS

The study showed that the EDOU was a lower cost and more effective treatment alternative for a refractory asthmatic population presenting to the Emergency Department. Several baseline MOS SF-36 domains proved useful in predicting or validating posttreatment clinical status, relapse, and total costs of care. Outcome SF-36 domain scores were also useful in identifying patients with the most favorable clinical, cost, and relapse rate outcomes at the study endpoint.

Routine preoperative "one-shot" intravenous pyelography is not indicated in all patients with penetrating abdominal trauma

BACKGROUND

To determine which patients need a "one-shot" intravenous pyelogram (IVP) before laparotomy for penetrating abdominal trauma.

STUDY DESIGN

Over a 15-month period, 240 laparotomies were performed for penetrating trauma at our urban level I trauma center. Prospectively collected data included clinical suspicion of genitourinary injury, results of preoperative IVP, intraoperative findings, and operative decisions influenced by the IVP.

RESULTS

Preoperative IVP was performed in 175 patients (73%). Of these, 71 (41%) had suspicion of a renal injury based on the presence of a flank wound or gross hematuria. The IVP was believed to influence operative decisions in six patients, all in this group. Each of these six patients had either a shattered kidney or a renovascular injury and had a nephrectomy performed with the knowledge that a normal functioning kidney was present on the contralateral side. No patient without a flank wound or gross hematuria had an IVP that was judged to be helpful intraoperatively. Preoperative IVP was helpful only in patients with flank wounds or gross hematuria. Nephrectomy was performed in two additional patients who did not undergo IVP, both of whom presented in shock.

CONCLUSIONS

Routine preoperative IVP is not necessary in all patients undergoing laparotomy for penetrating trauma. The number of IVPs can be safely reduced by 60% if the indications are narrowed to include only those stable patients with a flank wound or gross hematuria.

Costs of an emergency department-based accelerated diagnostic protocol vs hospitalization in patients with chest pain: a randomized controlled trial

CONTEXT

More than 3 million patients are hospitalized yearly in the United States for chest pain. The cost is over $3 billion just for those found to be free of acute disease. New rapid diagnostic tests for acute myocardial infarction (AMI) have resulted in the proliferation of accelerated diagnostic protocols (ADPs) and chest pain observation units.

OBJECTIVE

To determine whether use of an emergency department (ED)-based ADP can reduce hospital admission rate, total cost, and length of stay (LOS) for patients needing admission for evaluation of chest pain.

DESIGN

Prospective randomized controlled trial comparing admission rate, total cost, and LOS for patients treated using ADP vs inpatient controls. Total costs were determined using empirically measured resource utilization and microcosting techniques.

SETTING

A large urban public teaching hospital serving a predominantly African American and Hispanic population.

PATIENTS

A sample of 165 patients was randomly selected from a larger consecutive sample of 429 patients with chest pain concurrently enrolled in an ADP diagnostic cohort trial. Eligible patients presented to the ED with clinical findings suggestive of AMI or acute cardiac ischemia (ACI) but at low risk using a validated predictive algorithm.

MAIN OUTCOME MEASURES

Primary outcomes measured for each subject were LOS and total cost of treatment.

RESULTS

The hospital admission rate for ADP vs control patients was 45.2% vs 100% (P<.001). The mean total cost per patient for ADP vs control patients was $1528 vs $2095 (P<.001). The mean LOS measured in hours for ADP vs control patients was 33.1 hours vs 44.8 hours (P<.01).

CONCLUSIONS

In this trial, ADP saved $567 in total hospital costs per patient treated. Use of ED-based ADPs can reduce hospitalization rates, LOS, and total cost for low-risk patients with chest pain needing evaluation for possible AMI or ACI.

A comparison between emergency diagnostic and treatment unit and inpatient care in the management of acute asthma

BACKGROUND

Emergency diagnostic and treatment units (EDTUs) may provide an alternative to hospitalization for patients with reversible diseases, such as asthma, who fail to adequately respond to emergency department therapy.

OBJECTIVE

To evaluate the medical and cost-effectiveness, patient satisfaction, and quality of life of patients receiving EDTU care for acute asthma compared with inpatient care.

METHODS

A prospective, randomized clinical trial performed at 2 urban public hospitals enrolled patients with acute asthma (age range, 18-55 years) not meeting discharge criteria after 3 hours of emergency department therapy. Patients were treated with inhaled adrenergic agonists and steroids in an EDTU for up to 9 hours after randomization or with routine therapy in a hospital ward. Patients were followed up for 8 weeks.

MAIN OUTCOME MEASURES

Discharge rate from the EDTU, length of stay, relapse rates, days missed from work or school, days incapacitated during waking hours, symptom-free days and nights, nocturnal awakenings, direct medical costs, patients satisfaction, and patient quality of life.

RESULTS

The study consisted of 222 patients with asthma. Sixty-five patients (59%) treated in an EDTU were discharged home; the remainder were admitted to the hospital. There were no differences during the follow-up period in relapse rates (P = .74) or in any other morbidities between the EDTU and inpatient groups. There were significant differences in the length of stay, patient satisfaction, and quality of life favoring EDTU care. The mean (+/-SD) cost per patient in the EDTU group was $1202.79 +/- $1343.96, compared with $2247.32 +/- $1110.18 for the control group (P < .001).

CONCLUSIONS

Treatment of selected patients with asthma in an EDTU results in the safe discharge of most such patients. This study suggests that quality gains and cost-effective measures can be achieved by the use of such units.

A method of determining peritoneal penetration in gunshot wounds to the abdomen

BACKGROUND

It has previously been shown that 98% of gunshot wounds that penetrate the peritoneal cavity cause injuries that require surgical repair. Many gunshot wounds in the vicinity of the abdomen (GSWA) may actually be tangential and not penetrate the peritoneal cavity at all. Patients with such wounds may not require laparotomy. It is important to determine which patients with a potential tangential GSWA actually have penetration of the peritoneal cavity to minimize negative laparotomies. This study was undertaken to determine the sensitivity, specificity, and accuracy of diagnostic peritoneal lavage (DPL) in the determination of peritoneal penetration for patients who sustain GSWA.

METHODS

DPL was performed for all patients who had sustained a GSWA in whom peritoneal penetration was unclear, i.e., patients whose GSWA appeared to be tangential, thoracoabdominal, or transpelvic and for whom a clear indication for laparotomy (shock, peritonitis, etc.) did not exist. Our threshold for a positive DPL was 10,000 red blood cells (RBC)/mm3. A prospective data base was kept with information on the location of the wound, DPL result, findings at laparotomy, and outcome.

RESULTS

During a 4-year period, 429 consecutive DPLs were performed for GSWA at our urban Level I trauma center. One hundred fifty DPLs were positive, with more than 10,000 RBC/mm3. Six of these patients were found to have no peritoneal penetration at laparotomy (false-positive). The remaining 144 patients with positive DPLs were found to have operative injuries (true-positive). Of the 279 patients with DPL counts less than 10,000 RBC/mm3, 2 developed indications for laparotomy and were found to have intraperitoneal injuries (false-negative). The remaining 277 patients had no peritoneal injuries (true-negative). This was demonstrated either by laparotomy done for another indication (n = 7) or by uneventful inpatient observation for 24 hours (n = 270). The sensitivity, specificity, and accuracy of DPL in determining peritoneal penetration in GSWA is therefore 99, 98, and 98%, respectively.

CONCLUSION

For patients who sustain GSWA for whom peritoneal penetration is unclear, DPL is a sensitive, specific, and accurate test to determine the need for laparotomy. It remains our test of choice when confronted with these patients.

Feasibility of a rapid diagnostic protocol for an emergency department chest pain unit

STUDY OBJECTIVE

To evaluate the applicability of a short-stay protocol for exclusion of acute ischemic heart disease without hospital admission and to analyze these results in the context of a conceptual model.

METHODS

An observational study of patients who presented with chest pain to the emergency department of an 886-bed inner-city municipal hospital and who needed hospital admission to rule out acute myocardial infarction (AMI). Patients were assessed by ED attending physicians to determine eligibility for an alternative, 12-hour protocol in an ED chest pain observation unit (CPOU) followed by immediate exercise testing. Outcome measures were proportion of patients eligible for the short-stay protocol, risk factor profile, and reasons for exclusion.

RESULTS

Of 500 patients screened, 446 had sufficient data points to determine protocol eligibility. Of these, 238 (53.3%; 95% confidence interval [CI], 48.7% to 57.9%) were found to have low probability for AMI. After study exclusion criteria were applied to the patient cohort, 63 patients (14.1%; 95% CI, 10.9% to 17.3%) were eligible for the protocol. The most common reasons for exclusion were history of coronary artery disease (46%) and inability to perform an interpretable exercise tolerance test (42%).

CONCLUSION

Although most admitted patients with chest pain (53%) were at low probability for AMI, only a minority (14%) were eligible for a short-stay protocol that required patients to be free of known coronary artery disease and able to perform an exercise tolerance test. Factors affecting the operations and efficiency of a CPOU include clinical characteristics of the target patient population, protocol tests used, and hospital occupancy and reimbursement patterns.

Patient satisfaction with an emergency department chest pain observation unit

STUDY OBJECTIVE

Patient satisfaction is an essential outcome measure in the diagnosis and treatment of acute chest pain in the emergency department. We compared patient satisfaction with the diagnostic protocol of a chest pain observation unit (CPOU) and standard inpatient hospitalization.

METHODS

We prospectively studied patients who presented to the ED with chest pain and were found to have a low risk of acute myocardial infarction (AMI) but who still might have benefited from a diagnostic protocol to rule out AMI. Consenting patients (N = 104) were randomized to the CPOU (experimental) arm or the hospital inpatient (control) arm and assessed for satisfaction by means of an interview before hospital discharge.

RESULTS

The CPOU protocol scored higher on four summary ratings of overall patient satisfaction. Correlations between overall satisfaction, number, and type of problems with care, and patient characteristics demonstrated content validity and revealed strengths and improvements that might be made in CPOUs.

CONCLUSION

Patients were more satisfied with rapid diagnosis in the CPOU than with inpatient stays for acute chest pain. Our findings add important information to the standard practice of weighing clinical and cost outcomes between two medical care alternatives.

Computed tomography screens stable patients at risk for penetrating cardiac injury

OBJECTIVE

To determine the accuracy of CT of the chest in diagnosing the presence of cardiac injury in stable patients with penetrating chest injuries.

METHODS

A retrospective chart review of a convenience sample of stable patients with penetrating thoracic wounds evaluated for hemopericardium using chest CT at an urban level I trauma center.

RESULTS

60 stable patients with penetrating wounds in proximity to the heart underwent CT. Three patients had radiographic evidence of pericardial fluid, and 1 had an equivocal study. These 4 patients underwent subxiphoid pericardial window exploration: 2 had only clear fluid present, the other 2 had hemopericardium. The latter patients had a total of 3 cardiac and 1 diaphragmatic injuries, which were repaired at subsequent sternotomy. None of the 56 patients who had negative CTs had further clinical evidence of cardiac injury. The sensitivity, specificity, and accuracy of CT in this setting for hemopericardium are 100% (95% CI 18-100%), 96.6% (95% CI 88-100%), and 96.7% (95% CI 89-100%), respectively.

CONCLUSION

Chest CT may be a useful test for diagnosing the presence of hemopericardium in the setting of penetrating thoracic injury. With the caveat that the patient must be removed from a closely monitored environment, the authors the use of CT in stable patients with penetrating chest wounds whenever echocardiography is unavailable.

Experience with three prosthetic materials in temporary abdominal wall closure

There are circumstances that make abdominal wall closure unsafe and technically impossible after laparotomy for trauma. In these difficult cases, prosthetic materials may be necessary to temporarily close the abdominal wall. To determine the optimal prosthetic in these instances, a retrospective chart review was conducted in our urban Level I trauma center. Twenty-five patients received 31 abdominal wall prostheses over a 4-year period. There were 7, 8, and 10 patients with 7 Marlex, 9 Dexon, and 15 Goretex prostheses, respectively. Each patient had only one type of prosthesis placed. The average age was 30.7 +/- 12.0 years, injury severity score was 20.3 +/- 7.4, and abdominal trauma index was 35.9 +/- 18.0; there was no significant difference in these values between groups. Eight patients died soon after the prosthesis was placed (average, 12.9 days) secondary to ongoing shock or multiple organ failure. Three of the seven surviving Goretex patients (43%) were intentionally left with small hernias. Three of the six Dexon patients (50%) were left with hernias; one of these eviscerated on day 150 and subsequently died, and the others have disabling gigantic hernias. Three of the four Marlex patients (75%) developed fistulae as a result of erosion into the small bowel or colon. One Marlex patient suffered with a chronically draining abdominal wound for 398 days prior to definitive closure. Goretex appears to be the best prosthetic for temporary abdominal wall closure because it causes less inflammatory reaction because of its smooth surface. It is therefore easier to retrieve at the time of definitive closure and carries less risk of fistula formation than other prostheses. Our Dexon patients suffered with gigantic hernias and one died because of complications of evisceration. We have abandoned the use of Marlex in abdominal wall closure because of the high incidence of fistula formation. We advocate the use of Goretex in temporary abdominal wall closure in this challenging group of patients.

Aspiration of free blood from the peritoneal cavity does not mandate immediate laparotomy

The objective was to establish the relationship between the aspiration of free blood (+ASP) versus diagnostic peritoneal lavage (DPL), abdominal injury severity, hemodynamic instability, and the need for immediate operative intervention. We prospectively compared the significance of +ASP to +DPL in our level I trauma center. Consecutive patients received sequential needle tap, catheter aspiration (ASP), and DPL. If gross blood was withdrawn during the tap or ASP, it was returned to the peritoneal cavity before completing the DPL. The DPL was considered positive if there were > 100,000 RBCs for blunt injuries or anterior abdominal stab wounds, or > 10,000 RBCs for other penetrating injuries. During a 12-month period, 566 patients fulfilled the study criteria; they were 50 per cent blunt and 50 per cent penetrating trauma. There were 70 patients with both +ASP/+DPL, 30 with -ASP/+DPL and 4 with +ASP but -DPL. Exploratory laparotomy was performed on these 104 patients (18.4%), 22 of which were considered nontherapeutic. The ATI was statistically higher in the +ASP patients (14.9 +/- 12.9 versus 8.5 +/- 8.2, P < 0.05) but was not clinically different. Overall injury severity and hemodynamic stability were not different in the two groups. The sensitivity of DPL at detecting intra-abdominal injury was higher than the ASP group (98% versus 72%), but the specificities were equal (98%). Because +ASP patients are not more critically injured or unstable than +DPL patients, and because DPL is more accurate in detecting the need for operative intervention, aspiration should be abandoned as part of the DPL procedure in patients with abdominal trauma.

Selective management of anterior abdominal stab wounds

A policy of selective management of anterior abdominal stab wounds was evaluated in 333 consecutive patients. Laparotomy was performed based upon initial clinical assessment in 165 patients. There were six deaths (3.6%), major complications in 23 patients (14%), and 28 negative laparotomies (17%). Eighteen patients developed indications for laparotomy after 10.7 +/- 2.2 hours of observation. There were no deaths, major complications in two patients (11%), and four negative laparotomies (22%). One hundred fifty patients were observed and discharged after 1.8 +/- 0.1 days. Sensitivity, specificity, and positive and negative predictive values for initial clinical evaluation were 91%, 85%, 92%, and 83%, respectively. Length of hospitalization in the initially operated and in the delayed group was 9.5 +/- 0.6 and 10.6 +/- 2.6 days (NS), respectively. Most serious intra-abdominal injuries will declare themselves on initial clinical assessment. The remainder are less severe injuries and these patients can be safely observed without undue sequelae due to delay. The use of clinical assessment alone to prompt laparotomy is also cost effective based on analysis of hospital days for initial illness. No procedures are necessary to define penetration.

Cardiac allograft survival across major histocompatibility complex barriers in the rhesus monkey following T lymphocyte-depleted autologous marrow transplantation. III. Late allograft rejection

We have studied organ allograft survival in rhesus monkeys conditioned with myeloablative total-body irradiation and T cell-depleted autologous bone marrow transplantation then given a heterotopic MHC-mismatched cardiac allograft in the immediate postmyeloablative period. This model has enabled us to investigate the role of T cells in vascularized organ allograft rejection. We previously reported (1) that recipients of marrow depleted of T cells below a critical threshold (0.16% residual marrow T cells, or 0.14 x 10(5) infused T cells/kg) experienced a period of freedom from acute rejection associated with a profound nonspecific immune deficiency (determined by skin grafting). Resolution of the nonspecific immune deficiency was associated with late graft rejection. In the present report, we correlate the results of peripheral immune reconstitution studies and direct immunohistochemical analysis with allograft status in order to study T cell subsets involved in late rejection. We report that, in contrast with CD8+/CD28- T cells, CD16+ NK cells, and CD20+ B cells, late allograft rejection was associated with the return of peripheral CD4+ T cells and CD8+/CD28+ T cells, suggesting a critical role for one or both of these subsets in late allograft rejection in this model.

Bioflavonoid interaction with rat uterine type II binding sites and cell growth inhibition

Competition analysis with a number of known bioflavonoids demonstrated that these compounds (luteolin, quercetin, pelargonin) compete for [3H]estradiol binding to cytosol and nuclear type II sites in rat uterine preparations. The inhibition of [3H]estradiol binding to type II sites was specific and these bioflavonoids did not interact with the rat uterine estrogen receptor. Since estradiol stimulation of nuclear type II sites in the rat uterus is highly correlated with cellular hypertrophy and hyperplasia, we assessed the effects of these compounds on the growth of MCF-7 human breast cancer cells in culture and on estradiol stimulation of uterine growth in the immature rat. The data demonstrated that addition of quercetin (5-10 micrograms/ml) to MCF-7 cell cultures resulted in a dose-dependent inhibition of cell growth (DNA/flask). This effect was reversible by removal of quercetin from the culture medium, or by the addition of 10 nM estradiol-17 beta to these cell cultures containing this bioflavonoid. Since estradiol-17 beta (10 nM) stimulated nuclear type II sites and proliferation of MCF-7 cells, we believe bioflavonoid inhibition of MCF-7 cell growth may be mediated through an interaction with nuclear type II sites. This hypothesis was confirmed by in vivo studies which demonstrated that injection of luteolin or quercetin blocked estradiol stimulation of nuclear type II sites in the immature rat uterus and this correlated with an inhibition of uterine growth (wet and dry weight). These studies suggest bioflavonoids, through an interaction with type II sites, may be involved in cell growth regulation.

Cytosol type II sites in the rat uterus: interaction with an endogenous ligand

Previous studies from our laboratory demonstrated that normal, but not malignant tissues, contain a ligand which competes for [3H]estradiol binding to nuclear type II sites in the rat uterus. Since elevated nuclear levels of type II sites are correlated with estrogen stimulation of uterine growth and DNA synthesis, we believe this ligand may regulate cell growth. The present studies show that the ligand for nuclear type II sites also interacts with type II sites in uterine cytosol. This was demonstrated by dilution experiments which show that greater quantities of type II sites are measured in dilute (10 mg/ml) than in concentrated (40 mg/ml) uterine cytosol. Furthermore, stripping of uterine cytosol with 1% dextrancoated charcoal, or pre-binding cytosol type II sites to hydroxylapetite (HAP) prior to binding analysis, removed the ligand from these preparations such that high levels of type II sites were measured. Following charcoal stripping, cytosol type II sites demonstrated good specificity for estrogenic hormones but not progesterone, corticosterone, or the triphenylethylene anti-estrogen, nafoxidine. Since the level of type II sites in the cytosol always preceded and exceeded the level of this site measured in uterine nuclei at all times following estrogen treatment (0-96 h), we believe cytosol type II sites may function as an type II-ligand binding protein (LBP) which regulates the availability of the ligand for interaction with nuclear type II sites. This is consistent with our observation that type II sites are not depleted from uterine cytosol by estrogen treatment and nuclear type II sites are very tightly associated with the nuclear matrix.

Uterine type II estrogen-binding sites are not of eosinophil origin

A recent report by Lyttle et al. (Lyttle, C. R., Medlock, R. L., and Sheehan, D. M. (1984) J. Biol. Chem. 259, 2697-2700) suggested that nuclear type II sites in the rat uterus are of eosinophil origin and may represent [3H]estradiol binding to eosinophil peroxidase. To further evaluate this hypothesis we examined the response of nuclear type II sites to estrogen under conditions where eosinophils are not present. Results of our experiments show that physiological levels of estradiol-17 beta (10 nM for 72 h) will stimulate nuclear type II sites in highly purified cultures (21-25 days; 4 passages) of rat uterine stromal and myometrial cells. The magnitude of the response of type II sites to estradiol in these stromal (4-fold) and myometrial (80-fold) cell cultures was essentially identical to that observed in the uterine cell types following in vivo estrogen treatment. Since these highly purified cultures of uterine cells were prepared from the uterus of a 21-day ovariectomized rat which is devoid of eosinophils, we conclude that estradiol stimulation of nuclear type II sites is a direct intracellular response to estrogen which occurs independent of eosinophil accumulation. Furthermore, we have found that type II sites in the rat uterus are not peroxidase. This was demonstrated by experiments which show type II sites are present in the 39,000 X g supernatant fraction of uterine cytosol, whereas peroxidase activity is quantitatively recovered in the crude mitochondrial (39,000 X g) pellet. Likewise, the small amount of peroxidase activity (approximately 10%) in the total homogenate which contaminates our nuclear pellet preparations was extracted (98-100%) with 0.5 M CaCl2. Type II estrogen-binding sites (95-100%) remained associated with the nuclear pellet fraction after peroxidase extraction. Therefore, stimulation of cytosol and nuclear type II sites by estrogen in the rat uterus is a direct intracellular response to the hormone unrelated to eosinophil accumulation and/or peroxidase activity.

An endogenous inhibitor of [3H]estradiol binding to nuclear type II estrogen binding sites in normal and malignant tissues

Previous studies from our laboratory have demonstrated that nonneoplastic tissues, such as rat uterus, contain an endogenous inhibitor of [3H]estradiol binding to nuclear type II sites. Since the stimulation of nuclear type II estrogen binding sites in the rat uterus is highly correlated with the stimulation of uterine growth and DNA synthesis, we have suggested that this inhibitor may be an endogenous ligand for the type II site which may antagonize estrogenic response. The present studies demonstrate that normal mouse mammary gland cytosol contains very high levels of this inhibitor activity, whereas cytosol from mouse mammary tumors and human breast cancer contains very low quantities of this inhibitor. These results are consistent with the observations that rapidly proliferating neoplastic tissue contains very high quantities of nuclear type II sites and that this may be directly related to lower levels of this endogenous inhibitor in these tissues.

The effect of low dose continuous exposure to estradiol on the estrogen receptor (type I) and nuclear type II sites

These studies were done to evaluate the temporal relationships between cytoplasmic and nuclear estrogen receptors (type I sites), nuclear type II estrogen binding sites, and uterotropic response (true uterine growth; DNA content) after low dose estrogen administration to adult-ovariectomized rats by beeswax pellet implant. Administration of low dose (2.5 micrograms estradiol-17 beta/pellet) estrogen pellets resulted in a slight accumulation of nuclear type I sites (approximately 1700 sites per cell above ovariectomized controls) and a 2-fold stimulation of nuclear type II estrogen binding sites (approximately 5,000 sites per cell) at short times (1-24 h) after estrogen treatment. By 96 h, nuclear levels of type I sites were not different from control even though nuclear type II sites remained elevated and uterotropic response was maintained. Similar temporal responses were observed after treatment with a higher dose estradiol (20 micrograms/pellet) except that early response (1-24 h) to the hormone was accompanied by a more pronounced accumulation (approximately 3,000 sites per cell above control) of type I sites in the nucleus. By 96 h after the administration of the 20-micrograms estradiol pellet, nuclear type I sites declined to control, however nuclear type II sites continued to increase (approximately 30,000 sites per cell) and maximum uterotropic response was observed. Comparison of the results obtained with these two dose levels of estradiol suggested that at early times (1-24 h) after treatment only a very small quantity (approximately 1,700 sites per cell) of nuclear type I sites is required for uterine growth. Likewise, although nuclear type II sites can be maximally stimulated (approximately 30,000 sites per cell) by higher doses of estrogen (20 micrograms) only 5,000 sites per cell may be necessary for maximal response. Surprisingly, uterine growth was sustained by very low to non-measurable quantities of type I sites in the nucleus (96 h). Regardless of the initial numbers of type I sites translocated to the nucleus (approximately 1,700 sites per cell, 2.5 micrograms estradiol; approximately 3,000 sites per cell, 20 micrograms estradiol), at early times (1-24 h), these levels decline to control approximately 96 h after treatment. These results are not due to a decreased rate of estrogen release from the beeswax pellet implant and the data suggest a down-regulation of nuclear type I sites is a normal response to the hormone under these experimental conditions, even though maximum uterine growth is maintained.

Preliminary characterization of an endogenous inhibitor of [3H]estradiol binding in rat uterine nuclei

The rat uterus contains two classes of specific nuclear estrogen-binding sites which may be involved in estrogen action. Type I sites represent the classical estrogen receptor (Kd = 1 nM) and type II sites (Kd = 10-20 nM) are stimulated in the nucleus by estrogen under conditions which cause uterine hyperplasia. Dilution of uterine nuclear fractions from estrogen treated rats prior to quantitation of estrogen binding sites by [3H]estradiol exchange results in an increase (3- to 4-fold) in the measurable quantities of the type II site. Estimates of type I sites are not affected by dilution. These increases in type II sites following nuclear dilution occur independently of protein concentration and result from the dilution of a specific endogeneous inhibitor of [3H]estradiol binding to these sites. The inhibitor activity is present in cytosol preparations from rat uterus, spleen, diaphragm, skeletal muscle, and serum. Preliminary characterization of the inhibitor activity by Sephadex G-25 chromatography shows two distinct peaks which are similar in molecular weight (300). These components (alpha and beta) can be separated on LH-20 chromatography since the beta-peak component is preferentially retained on this lipophilic resin. Partial purification of the LH-20 beta inhibitor component by high performance liquid chromatography and gas-liquid chromatography-mass spectrometric analysis suggests the putative inhibitor activity is not steroidal in nature and consists of two very similar phenanthrene-like molecules (molecular weights 302 and 304). Analysis of cytosol preparations on LH-20 chromatography shows that non-neoplastic tissues (uterus, liver, lactating mammary gland) contain both and inhibitor components whereas estrogen-induced rat mammary tumors contain very low to nonmeasurable quantities of the beta-peak inhibitor activity.

Respiration-coupled calcium transport by membrane vesicles from Azotobacter vinelandii

Membrane vesicles, isolated from osmotic lysates of Azotobacter vinelandii spheroplasts in Tris-acetate buffer, rapidly accumulate calcium in the presence of an oxidizable substrate. The addition of D-lactate to vesicles increases the rate of calcium uptake by 34-fold; L-malate, NADH, NADPH, and reduced phenazine methosulfate are nearly as effective as lactate. The intravesicular calcium pool which accumulates under these conditions is rapidly discharged by isotopic exchange or in the presence of respiratory inhibitors, uncouplers, or EGTA. The uptake rates for calcium follow Michaelis-Menten kinetics yielding a Km of 48 microM and a V max of 45 nmoles/min/mg membrane protein. Initial rates of EGTA-induced calcium efflux also follow saturation kinetics, giving a V max identical to that for calcium entry; but the Km for exodus is 14 mM, assuming that free calcium accumulates in vesicles. The difference in the affinity of calcium for the entry and exit processes observed during respiration is sufficient to account for the estimated 150-fold calcium concentration gradient achieved under steady-state conditions. The uptake system is specific for calcium as opposed to other cations, but zinc and lanthanum are effective competitors. Calcium uptake is blocked when electron is inhibited by exposure of vesicles to p-chlormercuriphenylsulfonate, hydroxyquinoline-N-oxide, or cyanide, or under anoxic conditions. Divalent cation ionophores (A23187 and X537A) and proton ionophores (CCP and gramicidin D) also block calcium transport effectively. The electrogenic potassium ionophore valinomycin has no effect on lactate-dependent calcium uptake in the presence of potassium; but ionophores which induce electroneutral exchange of protons for sodium or potassium (monensin and nigericin, respectively) did block calcium transport in the presence of the appropriate cation. The fluorescence intensity of quinacrine (an amine probe) in the presence of A. vinelandii membrane vesicles is reduced by 25% on addition of lactate; the quenching is blocked by CCP. This indicates that a pH gradient (inside acid) is developed across the vesicle membrane during lactate oxidation. These results indicate that these membrane preparations contain vesicles of inverted topology (with respect to the intact cell) and suggest that calcium transport occurs by means of electroneutral calcium/proton antiport.

Release of beta-lysin from platelets caused by antigen-antibody complexes, purified enzymes, and platelet-aggregating substances

The release of beta-lysin, which followed the intravenous injection of antigen-antibody complexes, did not take place when these complexes were added to citrated whole blood but did occur in heparinized blood. beta-Lysin release in heparinized blood was inhibited by citrate but were reversed by the addition of calcium ions that implicated complement reactions. Fourteen different enzymes were added to platelet-rich plasma (PRP). Streptokinase, neuraminidase, papain, phospholipase C, sulfatase, and trypsin caused platelets to release significant quantities of beta-lysin, whereas elastase, phosphatase, protease, ribonuclease A, hyaluronidase, lipase, and pepsin caused little or no increase in the plasma beta-lysin concentration. One enzyme, fibrinolysin, inactivated beta-lysin faster than it was released. The enzyme-induced release of beta-lysin from PRP was often accompanied by a reduction in the number of platelets. The intravenous injection of streptokinase, neuraminidase, and sulfatase caused in vivo releases of beta-lysin into the plasma. The platelet-aggregating substances collagen, arachidonic acid, and adenosine 5'-diphosphate caused beta-lysin to be released from PRP. The platelet-aggregating substances L-epinephrine, zymosan, fibrinogen, reserpine, and serotonin caused little or no release of beta-lysin from platelets. The results of this study indicate that the release of beta-lysin during antigen-antibody-complement reactions, blood coagulation, phagocytosis, and inflammation could be enzyme mediated.

Interrelationship between serum beta-lysin, lysozyme, and the antibody-complement system in killing Escherichia coli

The effects of different serum components alone and in conjunction with each other on Escherichia coli B were investigated. In general, the viability, turbidity, and electron microscope results were compatible with the following conclusions. The most efficient killing and destruction of E. coli B occurred when beta-lysin, lysozyme, and the antibody-complement system functioned in cooperation with each other at the serum concentration in isotonic solutions. The addition of sucrose protected the bacteria from the lethal and lytic action of these agents. Elimination of lysozyme from serum had the least effect on bactericidal activity, even though lysozyme treatment caused the cell wall to separate from the cytoplasmic membrane and caused clear areas to appear in the inner granular layer of the cell wall. Beta-lysin removal had an intermediate effect on the serum bactericidal activity. Beta-lysin treatment caused cell walls to collapse, allowed cytoplasmic contents to leak out of the cells, and stopped the separation of cell wall and cytoplasmic membrane, which normally takes place in 0.5 M sucrose solution. Inactivation of the complement eliminated the serum bactericidal activity against E. coli B. After treatment with antibody and complement, the cell walls became thick and indistinct, a portion of the cytoplasmic contents escaped, and patches of the middle layer of the cell wall appeared in freeze-etch preparations. Beta-lysin damaged the cytoplasmic membrane, lysozyme damaged the inner peptidoglycan layer of the cell wall, and the antibody-complement system damaged both the middle lipopolysaccharide layer of the cell wall and the cytoplasmic membrane.

Release of beta-lysin from platelets by thrombin and by a factor produced in heparinized blood

Removal of calcium by either citrate, oxalate, or ethylenediaminetetraacetate inhibited coagulation of blood at an early stage and prevented the release of beta-lysin from platelets. In contrast, heparin caused platelet agglutination and stimulated beta-lysin release in vitro and in vivo. This release was calcium dependent and may have been due to a calcium-dependent reaction in the blood coagulation sequence. Thrombin which by-passed the early calcium-dependent stages of coagulation directly stimulated the release of beta-lysin from platelets. However, thrombin alone or in combination with other plasma factors was not as effective in releasing beta-lysin as the regular coagulation process. Thrombin's platelet degranulating activity correlated with its beta-lysin releasing activity. In contrast to thrombin, staphylococcal coagulase, which also by-passed the calcium-dependent stages of coagulation, coagulated citrated blood without releasing beta-lysin. The release of beta-lysin has been observed previously in the absence of blood coagulation, but this is the first observation of coagulation without beta-lysin release. It is clear that beta-lysin is released from platelets during coagulation by the direct action of thrombin and that it may be released in an earlier calcium-dependent reaction.