An appraisal of pharmacotherapy-pertinent literature published in 2021 and 2022 for clinicians caring for patients with thermal or inhalation injury

Studies focusing on pharmacotherapy interventions to aid patients after thermal injury are a minor focus in burn injury-centered studies and published across a wide array of journals, which challenges those with limited resources to keep their knowledge current. This review is a renewal of previous years' work to facilitate extraction and review of the most recent pharmacotherapy-centric studies in patients with thermal and inhalation injury. Twenty-three geographically dispersed, board-certified pharmacists participated in the review. A MeSH-based, filtered search returned 2,336 manuscripts over the previous 2-year period. After manual review, 98 (4%) manuscripts were determined to have a potential impact on current pharmacotherapy practice. The top 10 scored manuscripts are discussed. Only 17% of those reviewed were assessed to likely have little effect on current practice. The overall impact of the current cohort was higher than previous editions of this review, which is encouraging. There remains a need for investment in well-designed, high impact, pharmacotherapy-pertinent research for patients sustaining thermal or inhalation injuries.

Defining Pathogen and Susceptibility Patterns for Early Versus Late Ventilator Associated Pneumonia in Trauma Patients to Guide Empiric Treatment Decisions

INTRODUCTION

Studies have demonstrated that trauma patients with early-ventilator associated pneumonia (early-VAP, < 7 days) have decreased risk of methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa infections. We hypothesize that routinely using broad-spectrum antibiotics is unnecessary to treat trauma patients with the diagnosis of early-VAP.

METHODS

This retrospective cohort study included adult trauma patients with the diagnosis of VAP. The primary outcome was the presence of MRSA and/or P. aeruginosa in patients with early- and late-VAP. Secondary outcomes included the bacterial susceptibility of pathogens to methicillin, ampicillin/sulbactam, ceftriaxone, piperacillin/tazobactam, and cefepime. Intensive care unit (ICU) and hospital length of stay (LOS), ventilator-free days, and in-hospital mortality were also collected.

RESULTS

164 patients met inclusion criteria, and 208 organisms (n = 90 early vs n = 118 late) were identified by respiratory culture. The incidence of MRSA and P. aeruginosa in early-VAP was 7.7% (7/90) and 5.6% (5/90), respectively. The susceptibility of bacteria causing early-VAP to ampicillin/sulbactam and ceftriaxone was 73.3% (66/90) and 83.3% (75/90), respectively. Ventilator-free days at 30 days was similar between groups (P = .649). Patients with late-VAP spent more time in the ICU (P = .040); however, in-hospital mortality was higher in the early-VAP group (P = .012).

CONCLUSIONS

Ampicillin/sulbactam or ceftriaxone monotherapy did not provide reliable broad-spectrum coverage for early-VAP in our cohort. These findings highlight the importance of each institution performing a similar analysis to ensure adequate initial treatment of VAP.

Implementing a Discharge Opioid Bundle in Adult Trauma Patients Decreases the Amount of Opioids Prescribed at Discharge

BACKGROUND

Opioids remain the mainstay treatment of acute pain caused by trauma. The lack of evidence driven prescribing creates a challenging situation for providers. We hypothesized that the implementation of a trauma discharge opioid bundle (TDOB) would decrease the total morphine milligram equivalents (MME) prescribed at discharge while maintaining pain control.

METHODS

This was a pre-post study of adult trauma patients before and after implementation of a TDOB to guide the prescription of opioids and discharge prescription education in patients discharged from a level one trauma center. The pre-group and post-group, included consecutively discharged patients from September through November in 2018 and 2019. The primary outcome was the total MME prescribed at discharge.

RESULTS

A total of 377 patients met inclusion criteria. One hundred and fifty-one patients were included in the pre-group and 226 in the post-group. The total MME prescribed at discharge (225 ± [150-300] pre vs 200 ± [100-225] post, P = < .001) and maximum MME/day (45 ± [30-45] vs 30 ± [20-45], P = .004) were significantly less in the post-group. Incidence of outpatient refills within fourteen days were similar. More non-opioid pain adjuncts were prescribed post-intervention and discharge pain education was provided more frequently.

CONCLUSION

The implementation of a TDOB significantly reduced the MME prescribed at discharge without increasing the number of opioid refills.

Cefepime Daily Exposure and the Associated Impact on the Change in Sequential Organ Failure Assessment Scores and Vasopressors Requirement in Critically Ill Patients Using Repeated-Measures Mixed-Effect Modeling

IMPORTANCE

Sepsis and septic shock are major healthcare problems that need early and appropriate management.

OBJECTIVES

To evaluate the association of daily cefepime pharmacokinetic/pharmacodynamic (PK/PD) parameters with change in Sequential Organ Failure Assessment (SOFA) score and vasopressors requirement.

DESIGN SETTING AND PARTICIPANTS

This is a retrospective study. Adult ICU patients who received cefepime for Gram-negative pneumonia or bloodstream infection (BSI) and had cefepime concentrations measured were included. Daily cefepime exposure was generated and PK/PD parameters calculated for patients. Repeated-measures mixed-effect modeling was used to evaluate the impact of PK/PD on the outcomes.

MAIN OUTCOMES AND MEASURES

Change in daily SOFA score and vasopressors requirement.

RESULTS

A total of 394 and 207 patients were included in the SOFA and vasopressors analyses, respectively. The mean (±sd) age was 55 years (19) and weight 81 kg (29). For the change in SOFA score, daily SOFA score, mechanical ventilation, renal replacement therapy, and number of vasopressors were included. In the vasopressors analysis, daily SOFA score, day of therapy, and hydrocortisone dose were significant covariates in the final model. Achieving cefepime concentrations above the minimum inhibitory concentration (MIC) (T>MIC) for 100% of the dosing interval was associated with 0.006 µg/kg/min decrease in norepinephrine-equivalent dose. Cefepime PK/PD did not have an impact on the daily change in SOFA score.

CONCLUSIONS AND RELEVANCE

Achieving 100% T>MIC was associated with negligible decrease in vasopressors requirement in ICU patients with Gram-negative pneumonia and BSI. There was no impact on the change in SOFA score.

Survey of venous thromboembolism prophylaxis in trauma patients: current prescribing practices and concordance with clinical practice guidelines

Objectives

Pharmacological venous thromboembolism (VTE) prophylaxis is recommended in the vast majority of trauma patients. The purpose of this study was to characterize current dosing practices and timing of initiation of pharmacological VTE chemoprophylaxis at trauma centers.

Methods

This was an international, cross-sectional survey of trauma providers. The survey was sponsored by the American Association for the Surgery of Trauma (AAST) and distributed to AAST members. The survey included 38 questions about practitioner demographics, experience, level and location of trauma center, and individual/site-specific practices regarding the dosing, selection, and timing of initiation of pharmacological VTE chemoprophylaxis in trauma patients.

Results

One hundred eighteen trauma providers responded (estimated response rate 6.9%). Most respondents were at level 1 trauma centers (100/118; 84.7%) and had >10 years of experience (73/118; 61.9%). While multiple dosing regimens were used, the most common dose reported was enoxaparin 30 mg every 12 hours (80/118; 67.8%). The majority of respondents (88/118; 74.6%) indicated adjusting the dose in patients with obesity. Seventy-eight (66.1%) routinely use antifactor Xa levels to guide dosing. Respondents at academic institutions were more likely to use guideline-directed dosing (based on the Eastern Association of the Surgery of Trauma and the Western Trauma Association guidelines) of VTE chemoprophylaxis compared with those at non-academic centers (86.2% vs 62.5%; p=0.0158) and guideline-directed dosing was reported more often if the trauma team included a clinical pharmacist (88.2% vs 69.0%; p=0.0142). Wide variability in initial timing of VTE chemoprophylaxis after traumatic brain injury, solid organ injury, and spinal cord injuries was found.

Conclusions

A high degree of variability exists in prescribing and monitoring practices for the prevention of VTE in trauma patients. Clinical pharmacists may be helpful on trauma teams to optimize dosing and increase prescribing of guideline-concordant VTE chemoprophylaxis.

Risk Factors for Delirium and Association of Antipsychotic Use with Delirium Progression in Critically Ill Trauma Patients

Background

Delirium occurs frequently in critically ill and injured patients and is associated with significant morbidity and mortality. Limited data exists on the risk factors for developing delirium in critically ill trauma patients and the effect of antipsychotic (AP) medications on delirium progression.

Objective

The objective of this study is to determine the incidence of delirium in critically ill trauma versus non-trauma surgical patients and determine if the presence of trauma was associated with intensive care unit (ICU) delirium. Secondary outcomes included identifying risk factors for delirium and determining the impact of AP medication use on delirium progression in critically ill trauma patients.

Methods

This retrospective review studies adult trauma/surgical ICU patients admitted between May 2017-July 2018 to a level I trauma and tertiary referral center. Regression modeling was used to determine the impact of AP use on delirium-free days.

Results

Delirium was more common in critically ill trauma patients versus non-trauma surgical ICU patients [54/157 (34.4%) vs 42/270 (15.6%), P < .001]. Of the 54 trauma patients with delirium, 28 (52%) received an AP medication for delirium treatment and in the multiple linear regression analysis, AP use was significantly associated with fewer delirium-free days ( P = .02).

Discussion

Higher admission sequential organ failure assessment scores and increased length of stay were significantly associated with delirium onset in critically ill trauma patients. Use of AP medications for delirium treatment in this population had a negative impact on delirium-free days.

A review of the most impactful published pharmacotherapy-pertinent literature of 2019 and 2020 for clinicians caring for patients with thermal or inhalation injury

Keeping abreast with current literature can be challenging, especially for practitioners caring for patients sustaining thermal or inhalation injury. Practitioners caring for patients with thermal injuries publish in a wide variety of journals, which further increases the complexity for those with resource limitations. Pharmacotherapy research continues to be a minority focus in primary literature. This review is a renewal of previous years' work to facilitate extraction and review of the most recent pharmacotherapy-centric studies in patients with thermal and inhalation injury. Sixteen geographically dispersed, board-certified pharmacists participated in the review. A MeSH-based, filtered search returned 1,536 manuscripts over the previous 2-year period. After manual review and exclusions, only 98 (6.4%) manuscripts were determined to have a potential impact on current pharmacotherapy practices and included in the review. A summary of the 10 articles that scored highest are included in the review. Nearly half of the reviewed manuscripts were assessed to lack a significant impact on current practice. Despite an increase in published literature over the previous 2-year review, the focus and quality remain unchanged. There remains a need for investment in well-designed, high impact, pharmacotherapy-pertinent research for patients sustaining thermal or inhalation injuries.

Delineating the Role of Serum Immunoglobulin Titers in Burn Patients at High Risk for Herpes Simplex Virus Infection

Herpes simplex virus (HSV) is common in the population and reactivation of latent infection often occurs in times of physiologic stress, including postburn injury. Active HSV infection complicates burn injury recovery and increases morbidity. A retrospective chart review of high-risk burn patients (≥20%TBSA and/or facial burns) who had screening HSV immunoglobulin titers drawn from 2015 to 2018 was conducted. Titer levels and morbidity-related outcomes were compared between patients who developed active infection and those who did not. Fifty-six patients had serum HSV titers measured. Twenty-nine patients (52%) developed clinical signs of HSV infection, almost all of which (97%) suffered facial burns. Titers were ordered on median hospital day 1.5 (0.00-4.0) and infection occurred on day 8.0 (2.0-16). Median HSV-1,2 IgM titers were significantly increased in patients who developed clinically active HSV infection (0.71 [0.44-1.1] vs 0.52 [0.34-0.74], P = .02). Median HSV-1 IgG (P = .65) and HSV-2 IgG titers (P = .97) were not different between groups. Patients who developed active infection had a comparable hospital length of stay (27 [9.5-40] days vs 20 [8.0-28] days, P = .17) and ICU length of stay (26 [13-49] days vs 19 [11-27] days, P = .09) to those who did not develop infection. There was no difference in mortality. Increased HSV-1 and 2 IgM screening levels were associated with an increased risk of developing active HSV infection, and offer a specific screening modality in high-risk patients. Elevated IgM titers warrant further consideration for administration of HSV prophylaxis, as earlier intervention may prevent infection onset and minimize morbidity.

Neuroleptic Malignant Syndrome: A Potential Etiology of Multisystem Organ Failure in a Burn Patient

Neuroleptic malignant syndrome (NMS) is described in the medical literature but rarely seen among acutely ill trauma patients. A 44-year-old man with burns to the hands and back after a chemical explosion was transported to an outside facility where he received treatment for presumed acute coronary syndrome after developing ventricular tachycardia and elevated serum troponins after the exposure. His cardiac catheterization was unremarkable, but an echocardiogram revealed severe cardiomyopathy, and he was also in multisystem organ failure. He was transferred to our facility after hospital day 2 for treatment of his multisystem organ failure and 2% total body surface area burns. His laboratory results were remarkable for a creatine kinase of >100 000 units/L, and he required 14 g of intravenous calcium. Upon further investigation, the patient reported taking ziprasidone for his bipolar disorder, and he had a core temperature of 103.5 °F on his initial presentation to the outside facility. As he convalesced, the unifying diagnosis was NMS. NMS is a side effect of antipsychotic therapy and is manifested by hyperpyrexia, rigidity, autonomic instability, and altered consciousness. An elevated creatine kinase >100 000 units/L is almost pathognomonic for NMS. Patients can also present with leukocytosis, organ failure, and electrolyte disturbances including hypocalcemia. We hypothesized that dehydration, the warm environmental conditions at our patient's job, and immense stress resulting in a catecholamine surge following his trauma were inciting triggers to this event. This case highlights the importance of considering alternate diagnoses in patients whose clinical presentation does not fit the most "obvious cause."

Intraoperative liposomal bupivacaine for skin graft donor site analgesia: A retrospective cohort study

INTRODUCTION

Burn injury and reconstructive operations often result in severe pain, particularly at skin graft donor sites. Traditional local anesthetics administered intraoperatively control pain at donor sites, but the duration of action is short. Liposomal bupivacaine, a novel local anesthetic, can provide sustained-release analgesia for 72h. The primary aim of this study was to describe the efficacy of liposomal bupivacaine for postoperative donor site pain control for patients undergoing skin graft procedures.

METHODS

A retrospective cohort study was performed on patients who received a donor site liposomal bupivacaine field block and was compared to a matched control. Patients rated donor site pain on post-operative day 0 and 1, and stated whether the donor or graft site was more painful.

RESULTS

Fifty-eight patients were included. Twenty-nine patients received liposomal bupivacaine. Eighty-six percent of patients in the treatment group rated donor site pain as three or less on postoperative day 0 and 1, compared to 3.4% in the control (p<0.0001). Also, 76% of patients in the treatment group stated donor site pain was less than graft site pain, compared to 3.4% in the control (p<0.0001).

CONCLUSION

Patients who received liposomal bupivacaine reported less postoperative donor site pain and found the donor site to be less bothersome without major complications. Liposomal bupivacaine may be a safe and promising agent for prolonging postoperative analgesia and minimizing donor site pain.

Oral Administration of Injectable Ketamine During Burn Wound Dressing Changes

Providing adequate analgesia during burn wound care is essential to patient-centered care. Both oral and intravenous (IV) ketamine are often used for analgesia and sedation. Ketamine may improve analgesia and decrease opioid requirements for burn wound care. Oral ketamine wafers and tablets have been used as a safe alternative internationally but are unavailable in the United States. The purpose of this study was to compare opioid usage and patient satisfaction scores in patients with and without the use of oral injectable ketamine for burn wound care, with each patient serving as their own control. Ketamine, opioid, and benzodiazepine dosages recorded during dressing changes were compared to dressing changes without ketamine use that occurred before and after ketamine-associated sessions in each patient. Fourteen patients received oral ketamine at a median (interquartile range [IQR]) dose of 2.5 (2.2-2.7) mg/kg. Ketamine use significantly decreased opioid requirements when compared to wound care sessions that did not use ketamine both before (50 [IQR: 30-75] mg vs 75 [IQR: 46-91] mg median IV morphine equivalents, P = .0097) and after (50 [IQR: 30-75] mg vs 63 [IQR: 50-96] mg median IV morphine equivalents, P = .0042) the ketamine-associated sessions. One patient experienced hallucinations, and no adverse events were observed. Hence, oral administration of injectable ketamine was associated with a decrease in opioid requirements during dressing changes. Additionally, ketamine use improved patient satisfaction (P = .0034). Preliminary data suggest this promising analgesia method is safe and effective for burn wound care.

Leuco-crystal-violet micelle gel dosimeters: II. Recipe optimization and testing

In this study, recipe optimization of Leuco Crystal Violet (LCV) micelle gels made with the surfactant Cetyl Trimethyl Ammonium Bromide (CTAB) and the chemical sensitizer 2,2,2-trichloroethanol (TCE) was aided by a two-level three-factor designed experiment. The optimized recipe contains 0.75 mM LCV, 17.0 mM CTAB, 120 mM TCE, 25.0 mM tri-chloro acetic acid (TCAA), 4 wt% gelatin and ~96 wt% water. Dose sensitivity of the optimized gel is 1.5 times higher than that of Jordan's standard LCV micelle gel. Spatial integrity of the 3D dose distribution information in 1L phantoms filled with this recipe is maintained for >120 d. Unfortunately, phantoms made using the optimized recipe showed dose-rate dependence (14% difference in optical attenuation at the peak dose using electron beam irradiations at 100 and 400 MU min(-1)). Further testing suggests that the surfactant CTAB is the cause of this dose rate behaviour.

Metabolic, but not respiratory, acidosis increases bone PGE(2) levels and calcium release

A decrease in blood pH may be due to either a reduction in bicarbonate concentration ([HCO(3)(-)]; metabolic acidosis) or to an increase in PCO(2) (respiratory acidosis). In mammals, metabolic, but not respiratory, acidosis increases urine calcium excretion without altering intestinal calcium absorption, indicating that the additional urinary calcium is derived from bone. In cultured bone, chronic metabolic, but not respiratory, acidosis increases net calcium efflux (J(Ca)), decreases osteoblastic collagen synthesis, and increases osteoclastic bone resorption. Metabolic acidosis increases bone PGE(2) production, which is correlated with J(Ca), and inhibition of PGE(2) production inhibits this acid-induced J(Ca). Given the marked differences in the osseous response to metabolic and respiratory acidosis, we hypothesized that incubation of neonatal mouse calvariae in medium simulating respiratory acidosis would not increase medium PGE(2) levels, as observed during metabolic acidosis. To test this hypothesis, we determined medium PGE(2) levels and J(Ca) from calvariae incubated at pH approximately 7.1 to model either metabolic (Met; [HCO(3)(-)] approximately 11 mM) or respiratory (Resp; PCO(2) approximately 83 Torr) acidosis, or at pH approximately 7.5 as a control (Ntl). We found that after 24-48 and 48-51 h in culture, periods when cell-mediated J(Ca) predominates, medium PGE(2) levels and J(Ca) were increased with Met, but not Resp, compared with Ntl, and there was a direct correlation between medium PGE(2) levels and J(Ca). Thus metabolic, but not respiratory, acidosis induces the release of bone PGE(2), which mediates J(Ca) from bone.

Pyridopyrimidine analogues as novel adenosine kinase inhibitors

A novel series of pyridopyrimidine analogues 9 was identified as potent adenosine kinase inhibitors based on the SAR and computational studies. Substitution of the C7 position of the pyridopyrimidino core with C2' substituted pyridino moiety increased the in vivo potency and enhanced oral bioavailability of these adenosine kinase inhibitors.

Structure-activity studies of 5-substituted pyridopyrimidines as adenosine kinase inhibitors

The synthesis and SAR of a novel series of non-nucleoside pyridopyrimidine inhibitors of the enzyme adenosine kinase (AK) are described. It was found that pyridopyrimidines with a broad range of medium and large non-polar substituents at the 5-position potently inhibited AK activity. A narrower range of analogues was capable of potently inhibiting adenosine phosphorylation in intact cells indicating an enhanced ability of these analogues to penetrate cell membranes. Potent AK inhibitors were found to effectively reduce nociception in animal models of thermal hyperalgesia and persistent pain.

Prostaglandins regulate acid-induced cell-mediated bone resorption

Metabolic acidosis induces bone calcium efflux initially by physicochemical dissolution and subsequently by cell-mediated mechanisms involving inhibition of osteoblasts and stimulation of osteoclasts. In rat kidney, acidosis increases endogenous prostaglandin synthesis, and in bone, prostaglandins are important mediators of resorption. To test the hypothesis that acid-induced bone resorption is mediated by prostaglandins, we cultured neonatal mouse calvariae in neutral or physiologically acidic medium with or without 0.56 microM indomethacin to inhibit prostaglandin synthesis. We measured net calcium efflux and medium PGE(2) levels. Compared with neutral pH medium, acid medium led to an increase in net calcium flux and PGE(2) levels after both 48 h and 51 h, a time at which acid-induced net calcium flux is predominantly cell mediated. Indomethacin inhibited the acid-induced increase in both net calcium flux and PGE(2). Net calcium flux was correlated directly with medium PGE(2) (r = 0.879, n = 29, P < 0.001). Exogenous PGE(2), at a level similar to that found after acid incubation, induced net calcium flux in bones cultured in neutral medium. Acid medium also stimulated an increase in PGE(2) levels in isolated bone cells (principally osteoblasts), which was again inhibited by indomethacin. Thus acid-induced stimulation of cell-mediated bone resorption appears to be mediated by endogenous osteoblastic PGE(2) synthesis.

Epidemiology of participation: an Australian community study

STUDY OBJECTIVE

To determine the levels of participation in social and civic community life in a metropolitan region, and to assess differential levels of participation according to demographic, socioeconomic and health status. To contribute to policy debates on community participation, social capital and health using these empirical data.

DESIGN

Cross sectional, postal, self completed survey on health and participation.

SETTING

Random sample of the population from the western suburbs of Adelaide, the capital city of South Australia, a population of approximately 210 000.

PARTICIPANTS

2542 respondents from a sample of 4000 people aged 18 years and over who were registered on the electoral roll.

MAIN RESULTS

The response rate to the survey was 63.6% (n=2542). Six indices of participation, on range of social and civic activities, with a number of items in each, were created. Levels of participation were highest in the informal social activities index (46.7-83.7% for individual items), and lowest in the index of civic activities of a collective nature (2.4-5.9% for individual items). Low levels of involvement in social and civic activities were reported more frequently by people of low income and low education levels.

CONCLUSIONS

Levels of participation in social and civic community life in an urban setting are significantly influenced by individual socioeconomic status, health and other demographic characteristics. An understanding of the pattern of participation is important to inform social and health policy making. Increasing levels of participation will reduce social exclusion and is likely to improve the overall quality of community life.

Pharmacological characterization of recombinant human and rat P2X receptor subtypes

ATP functions as a fast neurotransmitter through the specific activation of a family of ligand-gated ion channels termed P2X receptors. In this report, six distinct recombinant P2X receptor subtypes were pharmacologically characterized in a heterologous expression system devoid of endogenous P2 receptor activity. cDNAs encoding four human P2X receptor subtypes (hP2X1, hP2X3, hP2X4, and hP2X7), and two rat P2X receptor subtypes (rP2X2 and rP2X3), were stably expressed in 1321N1 human astrocytoma cells. Furthermore, the rP2X2 and rP2X3 receptor subtypes were co-expressed in these same cells to form heteromultimeric receptors. Pharmacological profiles were determined for each receptor subtype, based on the activity of putative P2 ligands to stimulate Ca2+ influx. The observed potency and kinetics of each response was receptor subtype-specific and correlated with their respective electrophysiological properties. Each receptor subtype exhibited a distinct pharmacological profile, based on its respective sensitivity to nucleotide analogs, diadenosine polyphosphates and putative P2 receptor antagonists. Alphabeta-methylene ATP (alphabeta-meATP), a putative P2X receptor-selective agonist, was found to exhibit potent agonist activity only at the hP2X1, hP2X3 and rP2X3 receptor subtypes. Benzoylbenzoic ATP (BzATP, 2' and 3' mixed isomers), which has been reported to act as a P2X7 receptor-selective agonist, was least active at the rat and human P2X7 receptors, but was a potent (nM) agonist at hP2X1, rP2X3 and hP2X3 receptors. These data comprise a systematic examination of the functional pharmacology of P2X receptor activation.

Differences in static balance and weight distribution between normal subjects and subjects with chronic unilateral low back pain

Balance reactions are not routinely evaluated in patients with low back pain. The purpose of this study was to determine if there were differences in static balance and weight distribution between subjects with unilateral low back pain (N = 15) and pain-free controls (N = 15). Measurements included limits of stability (%LOS), target sway, weight distribution on each lower extremity in quiet standing, and center of gravity with measurements of maximal excursion in anterior/posterior and medial/lateral directions. Independent t tests were used to compare data between groups. Compared with control subjects, subjects with low back pain demonstrated greater anterior-posterior center of gravity excursion and total center of gravity excursion with eyes open and greater anterior-posterior, medial-lateral, and total center of gravity excursion, target sway, and %LOS with eyes closed. There was no difference in the weight-bearing distribution between groups. This study suggests that static balance in patients with chronic low back pain may be impaired and should be thoroughly evaluated and integrated into physical therapy treatment programs.

Inhibition of adenosine kinase during oxygen-glucose deprivation in rat cortical neuronal cultures

Adenosine kinase (AK) inhibitors potentiate the actions of endogenous adenosine (ADO) and ameliorate cerebral ischemic damage in animal models. The present study examined the effects of the AK inhibitor, 5-iodotubercidin (5-IT) in an in vitro model of neuronal ischemia, specifically, combined oxygen-glucose deprivation of rat cortical mixed neuronal-glial cultures. Oxygen-glucose deprivation caused extensive neuronal loss which was accompanied by a marked increase in ADO release into the extracellular medium, was ameliorated by exogenous ADO (10 microM(-1) mM), and was exacerbated by a high concentration of the selective A1 receptor antagonist 8-cyclopentyl-1,3-dimethylxanthine (CPT; 10 microM). 5-IT (1 microM) had no effect on extracellular ADO levels nor on neuronal loss. However, AK activity in these cultures was markedly suppressed during oxygen-glucose deprivation. Taken together, these data demonstrate a marked down-regulation of AK activity during oxygen-glucose deprivation in this in vitro model, providing an endogenous mechanism contributing to the accumulation of extracellular ADO, which exerts neuroprotective effects by activating the ADO A1 receptor.

Nitroaromatic amino acids as inhibitors of neuronal nitric oxide synthase

Nitric oxide (NO.) is an important biomodulator of many physiological processes. The inhibition of inappropriate production of NO. by the isoforms of nitric oxide synthase (NOS) has been proposed as a therapeutic approach for the treatment of stroke, inflammation, and other processes. In this study, certain 2-nitroaryl-substituted amino acid analogues were discovered to inhibit NOS. Analogues bearing a 5-methyl substituent on the aromatic ring demonstrated maximal inhibitory potency. For two selected inhibitors, investigation of the kinetics of the enzyme showed the inhibition to be competitive with l-arginine. Additionally, functional NOS inhibition in tissue preparations was demonstrated.

Role of progesterone on the control of scent marking in Suncus murinus viridescens (Blyth)

The effect of castration and administration of progesterone in different doses on the specialized integumentary glands and scent marking behavior in male musk shrew, Suncus murinus viridescens were studied. Castration effected a considerable atrophy of the secretory epithelial tissues of the flank, oral lip and perineal glands with marked regression in their secretory output. Further, the scent marking frequencies were also reduced and attained a minimum level by the end of 4 weeks after castration. Progesterone administration in effective doses reactivated all these specialized integumentary glands and the scent marking frequency in male shrews within a period of three weeks.

Maintenance of functioning human pituitary tumours in 'nude' athymic mice

Departments of Medicine and Histopathology, St George's Hospital Medical School, Cranmer Terrace, London, SW17 ORE

(Received 4 May 1978)

There are now many reports of the growth of various human malignant tumours such as colonic carcinoma and malignant melanoma in the 'nude' athymic mouse (Rygaard & Povlsen, 1969), but there are few instances of human benign tumours being transplanted successfully into these animals. Nevertheless, the possibility of using the 'nude' athymic mouse as a vehicle for maintaining pituitary adenomatous tissue in a viable state for a prolonged period under conditions which are more physiological than those of tissue culture has been examined.

Pituitary adenomas were obtained from seven patients undergoing craniotomy for the treatment of acromegaly and from three patients without acromegaly where the tumour was removed because of visual impairment. Part of the tissue was fixed in formol–saline for light microscopy, part was fixed in 4% glutaraldehyde in phosphate

The release of an immobilized lipoprotein fraction from atherosclerotic lesions by incubation with plasmin

A large amount of plasma low density lipoprotein is present in human aortic intima, and this can be removed and measured by electrophoresis directly from the minced tissue into an antibody-containing gel. We now find that, in addition to this electrophoretically mobile lipoprotein, there is an immobilized lipoprotein fraction than can be released from lesions by incubation of the tissue sample with plasmin or other proteolytic enzymes after the mobile lipoprotein has been removed. The concentration of immobilized lipoprotein is highly correlated with the concentration of the residual cholesterol (not mobile on electrophoresis) that has accumulated in the tissue (r = 0.702; P less than 0.001). Thus, in normal intima and early gelatinous lesions it is about 15% of the concentration of mobile lipoprotein, whereas in the atheroma lipid layers of fibrous or gelatinous plaques it may be 2 or 3 times greater than the concentration of mobile lipoprotein. This suggests that immobilization of plasma lipoprotein is an intermediate step in the irreversible deposition of extracellular cholesterol in atherosclerotic lesions. Incubation with plasmin allowed maximum release of lipoprotein: plasmin = crude collagenase greater than trypsin greater than "pure" collagenase greater than chondroitinase ABC in order of their relative effectiveness. The concentration of immobilized lipoprotein was significantly correlated (r = 0.793; P less than 0.001) with the concentration in the tissue of fibrin or other insoluble derivatives of fibrinogen ("fibrin"). In aliquots of lesions incubated with varying amounts of plasmin for varying times there was a constant relation between release of lipoprotein and release of fibrin-degradation products. Together, these findings suggest that the lipoprotein is associated with insoluble "fibrin". This appears to be of considerable clinical interest, suggesting a synergism between lipoprotein and fibrinogen in the accumulation of lipid in lesions.

Insoluble "fibrin" in human aortic intima. Quantitative studies on the relationship between insoluble "fibrin", soluble fibrinogen and low density lipoprotein

A quantitative assay for fibrin or other insoluble fibrin-like antigens ("fibrin") in small samples of intima is described. Tissue samples were subjected to electrophoresis directly from the intima into an antibody-containing gel to remove and measure fibrinogen and other soluble fibrin reactive antigens (FRA). The residual tissue was then exhaustively incubated with plasmin, and the soluble fragments generated from the insoluble "fibrin" were measured by quantitative immunoelectrophoresis. "Fibrin" accounted for about 2% of the tissue dry weight in normal intima and the ratio fibrinogen/"fibrin" was 1-1.5. In the gelatinous lesions, which seem to be the precursors of fibrous plaques, there was a small increase in "fibrin" but a substantial increase in fibrinogen and low density (LD)-lipoprotein, and the ratio fibrinogen/"fibrin" rose to about 3, which suggests that the increase in "fibrin" is secondary to increased permeation of fibrinogen. At the edges of large plaques there was also a threefold increase in fibrinogen, but "fibrin" increased fivefold, and accounted for 10% of the tissue dry weight. The same high concentration was found in the centres of large fibrous plaques with advanced atheroma lipid. Raised levels of "fibrin" were accompanied by raised levels of fibrinogen in most tissue samples. About 80% of the total soluble FRA could be clotted with thrombin; there was no significant difference between normal intima and lesions, and the proportion clotted was not related to "fibrin" content.