A lower motor neuron disease in takahē (Porphyrio hochstetteri) is an endoplasmic reticulum storage disease

AIMS

To investigate the pathogenesis of a disease in takahē with intracytoplasmic inclusion bodies in lower motor neurons.

METHODS

Four cases aged between 5 and 12 years, from three different wildlife sanctuaries in New Zealand were examined. Of these, only one had signs of spinal dysfunction in the form of paresis. Stained paraffin sections of tissues were examined by light microscopy and immunostained sections of the ventral horn of the spinal cord by confocal microscopy. Epoxy resin sections of the bird with spinal dysfunction were examined by electron microscopy.

RESULTS

Two types of inclusion bodies were noted, but only in motor neurons of the ventral spinal cord and brain stem. These were large globoid eosinophilic bodies up to 5 µm in diameter, and yellow/brown granular inclusions mostly at the pole of the cell. The globoid bodies stained with Luxol fast blue but not with periodic acid Schiff (PAS), or Sudan black. The granular inclusions stained with Luxol fast blue, PAS and Sudan black. Both bodies were slightly autofluorescent. On electron microscopy the globoid bodies had an even electron-dense texture and were bound by a membrane. Beneath the membrane were large numbers of small intraluminal vesicles. The smaller granular bodies were more heterogeneous, irregularly rounded and membrane-bound accumulations of granular electron-dense material, often with electron-lucent vacuoles. Others were more vesicular but contained varying amounts of electron-dense material. The large globoid bodies did not immunostain for lysosomal markers lysosomal associated protein 1 (LAMP1) or cathepsin D so they were not lysosomal. The small granular bodies stained for cathepsin D by a chromogenic method. A kindred matrix analysis showed two cases to be as closely related as first cousins, and another case was almost as closely related to one of them, but the fourth bird was unrelated to any other.

CONCLUSIONS

It was concluded that this was an endoplasmic reticulum storage disease due to a specific protein misfolding within endoplasmic reticulum. It was rationalised that the two types of inclusions reflected the same aetiology, but that misfolded protein in the smaller granular bodies had entered the lysosomal system via endoplasmic reticulum autophagy. Although the cause was unclear, it most likely had a genetic aetiology or predisposition and, as such, has clinical relevance.

Causes of mortality of kiwi (Apteryx spp.) in New Zealand: a retrospective analysis of post-mortem records, 2010-2020

AIMS

To examine and assess causes of mortality of kiwi (Apteryx spp.) submitted to Massey University between 2010 and 2020 across the five recognised species according to location, age group and captivity status in New Zealand.

METHODS

Post-mortem reports were obtained from the Massey University/Te Kunenga ki Pūrehuroa School of Veterinary Science/Wildbase Pathology Register. Inclusion criteria were all species of kiwi with a date of post-mortem examination between August 2010 and August 2020. Data from each report was exported, categorised and compared using Microsoft Excel.

RESULTS

Of a total of 1,005 post-mortem reports, there were 766 North Island brown kiwi (NIBK; A. mantelli), 83 tokoeka (A. australis), 73 rowi (A. rowi), 49 great spotted kiwi (A. haastii), and 34 little spotted kiwi (A. owenii). This comprised 19 eggs/embryos, 125 neonatal, 473 juvenile, 153 subadult, and 235 adult kiwi. There were 615 kiwi from wild populations, 148 from sanctuary populations, 238 from captivity, and four from unspecified locations. The leading cause of death was trauma, affecting 322 (32.0 (95% CI = 29.2-35.0)%) kiwi including 289 (37.3 (95% CI = 26.0-31.7)%) NIBK. Nearly half of these died from predation by mustelids, with losses recorded from neonates to adults and clustered in the central to southern North Island. Predation by dogs was the second most common cause of death, killing 84 (8.4 (95% CI = 6.7-10.2)%) kiwi, of which 65.5% came from the northern districts of the North Island. Non-infectious disease killed 214 (21 (95% CI = 18.8-24.0)%) kiwi, and included developmental deformities, gastrointestinal foreign bodies and predator trap injuries. Infectious disease killed 181 (18.0 (95% CI = 15.7-20.5)%) kiwi and the proportion decreased with age, with common diagnoses including coccidiosis, bacterial septicaemia, avian malaria, and fungal respiratory disease. Starvation affected 42 (4.2 (95% CI = 3.0-5.6)%) kiwi, comprised of mainly neonatal or juvenile individuals from wild or sanctuary populations, with a higher percentage seen in tokoeka (11/83; 13.3%) compared to other species (min 0%, max 5.9%). The cause of death was undetermined in 246 (24.5 (95% CI = 21.8-27.3)%) cases, which was most often due to poor preservation of remains. This included 33/73 (46%) rowi and 32/83 (39%) tokoeka, and affected mainly birds from sanctuary and wild populations.

CONCLUSIONS

This study enhances our understanding of causes of mortality in captive, wild and sanctuary populations of all kiwi species and age groups within contemporary New Zealand.

An engineered ligand trap inhibits leukemia inhibitory factor as pancreatic cancer treatment strategy

Leukemia inhibitory factor (LIF), a cytokine secreted by stromal myofibroblasts and tumor cells, has recently been highlighted to promote tumor progression in pancreatic and other cancers through KRAS-driven cell signaling. We engineered a high affinity soluble human LIF receptor (LIFR) decoy that sequesters human LIF and inhibits its signaling as a therapeutic strategy. This engineered 'ligand trap', fused to an antibody Fc-domain, has ~50-fold increased affinity (~20 pM) and improved LIF inhibition compared to wild-type LIFR-Fc, potently blocks LIF-mediated effects in pancreatic cancer cells, and slows the growth of pancreatic cancer xenograft tumors. These results, and the lack of apparent toxicity observed in animal models, further highlights ligand traps as a promising therapeutic strategy for cancer treatment.

An engineered antibody binds a distinct epitope and is a potent inhibitor of murine and human VISTA

V-domain immunoglobulin (Ig) suppressor of T cell activation (VISTA) is an immune checkpoint that maintains peripheral T cell quiescence and inhibits anti-tumor immune responses. VISTA functions by dampening the interaction between myeloid cells and T cells, orthogonal to PD-1 and other checkpoints of the tumor-T cell signaling axis. Here, we report the use of yeast surface display to engineer an anti-VISTA antibody that binds with high affinity to mouse, human, and cynomolgus monkey VISTA. Our anti-VISTA antibody (SG7) inhibits VISTA function and blocks purported interactions with both PSGL-1 and VSIG3 proteins. SG7 binds a unique epitope on the surface of VISTA, which partially overlaps with other clinically relevant antibodies. As a monotherapy, and to a greater extent as a combination with anti-PD1, SG7 slows tumor growth in multiple syngeneic mouse models. SG7 is a promising clinical candidate that can be tested in fully immunocompetent mouse models and its binding epitope can be used for future campaigns to develop species cross-reactive inhibitors of VISTA.

Engineering a potent inhibitor of matriptase from the natural hepatocyte growth factor activator inhibitor type-1 (HAI-1) protein

Dysregulated matriptase activity has been established as a key contributor to cancer progression through its activation of growth factors, including the hepatocyte growth factor (HGF). Despite its critical role and prevalence in many human cancers, limitations to developing an effective matriptase inhibitor include weak binding affinity, poor selectivity, and short circulating half-life. We applied rational and combinatorial approaches to engineer a potent inhibitor based on the hepatocyte growth factor activator inhibitor type-1 (HAI-1), a natural matriptase inhibitor. The first Kunitz domain (KD1) of HAI-1 has been well established as a minimal matriptase-binding and inhibition domain, whereas the second Kunitz domain (KD2) is inactive and involved in negative regulation. Here, we replaced the inactive KD2 domain of HAI-1 with an engineered chimeric variant of KD2/KD1 domains and fused the resulting construct to an antibody Fc domain to increase valency and circulating serum half-life. The final protein variant contains four stoichiometric binding sites that we showed were needed to effectively inhibit matriptase with a K_i of 70 ± 5 pm, an increase of 120-fold compared with the natural HAI-1 inhibitor, to our knowledge making it one of the most potent matriptase inhibitors identified to date. Furthermore, the engineered inhibitor demonstrates a protease selectivity profile similar to that of wildtype KD1 but distinct from that of HAI-1. It also inhibits activation of the natural pro-HGF substrate and matriptase expressed on cancer cells with at least an order of magnitude greater efficacy than KD1.

Development of a Protease Biosensor Based on a Dimerization-Dependent Red Fluorescent Protein

Dysregulated activity of the protease matriptase is a key contributor to aggressive tumor growth, cancer metastasis, and osteoarthritis. Methods for the detection and quantification of matriptase activity and inhibition would be useful tools. To address this need, we developed a matriptase-sensitive protein biosensor based on a dimerization-dependent red fluorescent protein (ddRFP) reporter system. In this platform, two adjoining protein domains, connected by a protease-labile linker, produce fluorescence when assembled and are nonfluorescent when the linker is cleaved by matriptase. A panel of ddRFP-based matriptase biosensor designs was created that contained different linker lengths between the protein domains. These constructs were characterized for linker-specific cleavage, matriptase activity, and matriptase selectivity; a biosensor containing a RSKLRVGGH linker (termed B4) was expressed at high yields and displayed both high catalytic efficiency and matriptase specificity. This biosensor detects matriptase inhibition by soluble and yeast cell surface expressed inhibitor domains with up to a 5-fold dynamic range and also detects matriptase activity expressed by human cancer cell lines. In addition to matriptase, we highlight a strategy that can be used to create effective biosensors for quantifying activity and inhibition of other proteases of interest.

Cell-Binding Assays for Determining the Affinity of Protein-Protein Interactions: Technologies and Considerations

Determining the equilibrium-binding affinity (Kd) of two interacting proteins is essential not only for the biochemical study of protein signaling and function but also for the engineering of improved protein and enzyme variants. One common technique for measuring protein-binding affinities uses flow cytometry to analyze ligand binding to proteins presented on the surface of a cell. However, cell-binding assays require specific considerations to accurately quantify the binding affinity of a protein-protein interaction. Here we will cover the basic assumptions in designing a cell-based binding assay, including the relevant equations and theory behind determining binding affinities. Further, two major considerations in measuring binding affinities-time to equilibrium and ligand depletion-will be discussed. As these conditions have the potential to greatly alter the Kd, methods through which to avoid or minimize them will be provided. We then outline detailed protocols for performing direct- and competitive-binding assays against proteins displayed on the surface of yeast or mammalian cells that can be used to derive accurate Kd values. Finally, a comparison of cell-based binding assays to other types of binding assays will be presented.

Pathology and Epidemiology of Stillbirth in New Zealand Sea Lions (Phocarctos hookeri) From Enderby Island, Auckland Islands, 1998-2012

Stillbirth is a small and often cryptic fraction of neonatal mortality in mammals including pinnipeds. As part of an investigation into the poor reproductive success of the endangered New Zealand sea lion (Phocarctos hookeri), archived tissues from 37 stillborn pups born on Enderby Island between 1998 and 2012 were examined using histopathological techniques. Apart from bronchopneumonia with neutrophilic infiltration in 4 cases, few inflammatory conditions were identified in stillborn pups. However, 27/32 (84%) stillborn pups had aspirated squames present in the respiratory tract, without meconium. It is unclear if this finding represents fetal distress during parturition or whether it is a normal finding for this species. Three pups lacked histological evidence of hepatic glycogen storage, which may indicate placental defects or maternal undernutrition. No evidence of infectious disease was found on histopathological analysis, consistent with the low seroprevalence in New Zealand of infections known to cause reproductive failure in other pinniped species. This study forms an important baseline for further examination of stillborn New Zealand sea lion pups, as pup mortality is investigated as a contributor to the species' decline.

The effects of high-fat diet, branched-chainamino acids and exercise on female C57BL/6 mouse Achilles tendon biomechanical properties

Objectives

The goals of this study were: 1) to determine if high-fat diet (HFD) feeding in female mice would negatively impact biomechanical and histologic consequences on the Achilles tendon and quadriceps muscle; and 2) to investigate whether exercise and branched-chain amino acid (BCAA) supplementation would affect these parameters or attenuate any negative consequences resulting from HFD consumption.

Methods

We examined the effects of 16 weeks of 60% HFD feeding, voluntary exercise (free choice wheel running) and BCAA administration in female C57BL/6 mice. The Achilles tendons and quadriceps muscles were removed at the end of the experiment and assessed histologically and biomechanically.

Results

HFD feeding significantly decreased the Achilles tendon modulus without histological alterations. BCAA administration significantly decreased the stiffness of Achilles tendons in the exercised normal diet mice. Exercise partially ameliorated both the weight gain and glucose levels in the HFD-fed mice, led to a significant decrease in the maximum load of the Achilles tendon, and an increase in the average fibril diameter of the quadriceps femoris muscle. There were significant correlations between body weight and several biomechanical properties, demonstrating the importance of controlling obesity for maintaining healthy tendon properties.

Conclusions

In summary, this study showed a significant impact of obesity and body weight on tendon biomechanical properties with limited effects of exercise and BCAAs.

Cite this article: Bone Joint Res 2013;2:186–92.

An atypical genotype of Toxoplasma gondii as a cause of mortality in Hector's dolphins (Cephalorhynchus hectori)

Hector's dolphins (Cephalorhynchus hectori) are a small endangered coastal species that are endemic to New Zealand. Anthropogenic factors, particularly accidental capture in fishing nets, are believed to be the biggest threat to survival of this species. The role of infectious disease as a cause of mortality has not previously been well investigated. This study investigates Toxoplasma gondii infection in Hector's dolphins, finding that 7 of 28 (25%) dolphins examined died due to disseminated toxoplasmosis, including 2 of 3 Maui's dolphins, a critically endangered sub-species. A further 10 dolphins had one or more tissues that were positive for the presence of T. gondii DNA using PCR. Genotyping revealed that 7 of 8 successfully amplified isolates were an atypical Type II genotype. Fatal cases had necrotising and haemorrhagic lesions in the lung (n=7), lymph nodes (n=6), liver (n=4) and adrenals (n=3). Tachyzoites and tissue cysts were present in other organs including the brain (n=5), heart (n=1), stomach (n=1) and uterus (n=1) with minimal associated inflammatory response. One dolphin had a marked suppurative metritis in the presence of numerous intra-epithelial tachyzoites. No dolphins had underlying morbillivirus infection. This study provides the first evidence that infectious agents could be important in the population decline of this species, and highlights the need for further research into the route of entry of T. gondii organisms into the marine environment worldwide.

Identification of Vibrio harveyi as a causative bacterium for a tail rot disease of sea bream Sparus aurata from research hatchery in Malta

A bacterial disease was reported from gilthead sea bream (Sparus aurata) within a hatchery environment in Malta. Symptoms included complete erosion of tail, infection in the eye, mucous secretion and frequent mortality. A total of 540 strains were initially isolated in marine agar from different infected body parts and culture water sources. Subsequently 100 isolates were randomly selected, identified biochemically and all were found to be Vibrio harveyi-related organisms; finally from 100 isolates a total of 13 numbers were randomly selected and accurately identified as V. harveyi by 16S rRNA gene sequencing and species-specific PCR. Ribotyping of these strains with HindIII revealed total of six clusters. In vivo challenge study with representative isolates from each cluster proved two clusters each were highly pathogenic, moderately pathogenic and non-pathogenic. All 13 isolates were positive for hemolysin gene, a potential virulence factor. Further analysis revealed probably a single copy of this gene was encoded in all isolates, although not in the same locus in the genome. Although V. harveyi was reported to be an important pathogen for many aquatic organisms, to our knowledge this might be the first report of disease caused by V. harveyi and their systematic study in the sea bream hatchery from Malta.

Dimethylheptyl-THC-11 oic acid: a nonpsychoactive antiinflammatory agent with a cannabinoid template structure

OBJECTIVE

To assess the antiinflammatory activity of dimethylheptyl-THC-11 oic acid (DMH-11C), a nonpsychoactive synthetic derivative of tetrahydrocannabinol.

METHODS

Acute inflammation was induced by injection of interleukin-1beta and tumor necrosis factor alpha into subcutaneous air pouches formed on the backs of mice. Inflammation was quantified 6 hours later by pouch fluid leukocyte counts. Adjuvant-induced polyarthritis in rats was used as a model of chronic inflammation and joint tissue injury. Animals were either untreated, treated with safflower oil, or treated with DMH-11C in safflower oil. Arthritis was assessed by clinical observation and by histomorphologic evaluation of tibiotarsal joints.

RESULTS

Oral administration of DMH-11C reduced the accumulation of pouch fluid leukocytes and significantly reduced the severity of adjuvant-induced polyarthritis. Histopathologic studies of tibiotarsal joints showed that DMH-11C treatment attenuated pannus formation and joint tissue injury.

CONCLUSION

DMH-11C suppresses acute inflammation in the subcutaneous air pouch in mice and chronic joint inflammation characteristic of adjuvant disease in rats. These results demonstrate the potential use of this nonpsychoactive cannabinoid as an antiinflammatory agent.

Correlation between frequency of tuberculosis and compliance with control strategies

OBJECTIVE

To determine if compliance with annual tuberculosis skin testing correlated with the number of cases of tuberculosis seen in patients and healthcare workers.

DESIGN

Survey using a written questionnaire.

SETTING AND PARTICIPANTS

159 Veterans' Administration facilities.

RESULTS

Hospitals that reported that > 80% of their healthcare workers received annual skin tests saw 12.7 patient cases per 10,000 admissions and 4.0 healthcare worker cases per 10,000 personnel. Facilities in which < 20% of their healthcare workers were given annual skin tests saw 4.5 cases per 10,000 admissions and 1.6 cases in healthcare workers per 10,000 personnel (P < .001 for patients and P = .31 for healthcare workers). The ratio of the median number of patients placed in acid-fast bacilli (AFB) isolation to the median number of patients with confirmed tuberculosis was 12. There was no correlation of this ratio with the number of cases of tuberculosis in patients or healthcare workers seen in each facility.

CONCLUSION

Compliance with annual tuberculosis skin testing was related directly to the rate of tuberculosis seen in patients. More standardized policies for placing patients in AFB isolation are needed to control for potentially costly variation among facilities. These measures should have highest priority in the control of tuberculosis in the healthcare setting, before implementing still more expensive interventions.

Receptor mediation in cannabinoid stimulated arachidonic acid mobilization and anandamide synthesis

Numerous reports have suggested that increased synthesis of eicosanoids is a significant effect of cannabinoids in several models including the human. To address the question of receptor mediation in this process we have carried out experiments using oligonucleotides that are antisense to the CB1 and to the CB2 receptors. We have synthesized sense, antisense and random oligonucleotide probes to test for receptor involvement in THC stimulation of arachidonic acid release in three cell lines of both central and peripheral origin. Treatment of N18 mouse neuroblastoma cells with the CB1 antisense probe, at two concentrations, resulted in a dramatic decrease of THC stimulated arachidonate release while treatment with antisense CB2 was less effective. Synthesis of the novel eicosanoid, anandamide, was also reduced by antisense CB1 but not by antisense CB2. Western blot analysis indicated a decreased level of CB1 in CB1 antisense treated cells. The CB1 antagonist, SR141716A, was effective in reducing the THC elevated levels of free arachidonate in these cells in agreement with the antisense data. In the macrophage line, RAW 264.7, we found that while the sense, the random and the CB1 antisense oligonucleotides were ineffective, the CB2 antisense probe gave significant reductions of the THC induced response. The CB2 probe was also effective in reducing the release of arachidonate in WI-38 human lung fibroblasts. These findings support the idea of a receptor mediated process for cannabinoid stimulation of eicosanoid synthesis.

Stimulation of anandamide biosynthesis in N-18TG2 neuroblastoma cells by delta 9-tetrahydrocannabinol (THC)

A concentration-related stimulation of anandamide (arachidonylethanolamide) synthesis by delta 9-tetrahydrocannabinol (THC) was observed in N-18TG2 neuroblastoma cells. Anandamide was detected and measured using an approach in which [3H]arachidonic acid and [14C]ethanolamine were incorporated into the phospholipids of subconfluent monolayers of cells, and the radiolabeled products were analyzed by TLC following agonist exposure. Both precursors showed similar concentration-response relationships and time dependencies consistent with the production of a product containing both the ethanolamine and arachidonyl moieties. The radiolabeled product also migrated together with authentic anandamide on two-dimensional TLC, confirming its identity as arachidonylethanolamide. Approximately two-thirds of the observed synthesis could be inhibited by 1 microM wortmannin, an agent previously reported to inhibit THC-stimulated arachidonic acid release. These findings are in agreement with reports showing that THC can mobilize phospholipid bound arachidonic acid, leading to the production of other eicosanoids.

Phospholipase participation in cannabinoid-induced release of free arachidonic acid

The exposure of cells in culture to cannabinoids results in a rapid and significant mobilization of phospholipid bound arachidonic acid. In vivo, this effect has been observed as a rise in eicosanoid tissue levels that may account for some of the pharmacological actions of delta 9-tetrahydrocannabinol (THC), the major psychoactive cannabinoid. Fluoroaluminate pretreatment of mouse peritoneal cells potently reduced the cannabinoid response, while promoting arachidonate release on its own, consistent with earlier observations that this effect may be a receptor/G-protein-mediated process. Further support for receptor mediation was the demonstration of saturable, high-affinity cannabinoid binding in these cells. THC potency was reduced in the presence of ethanol, and was accompanied by significant increases in phosphatidylethanol (PdEt) levels, a unique product of phospholipase D (PLD) activity. THC-dependent arachidonate release was reduced partially in similar amounts by either propranolol or wortmannin, further implicating PLD as a mediator of THC action. A central role for diacylglyceride (DAG), a secondary product of PLD metabolism, in this THC-induced process, both as a source of arachidonate and as a stimulator of protein kinase C (PKC), is supported by the data in this report. Cells exposed to phorbol ester for 18 hr prior to THC challenge became less responsive, indicating a possible role for PKC. The involvement of PKC further suggests participation by phospholipase A2 (PLA2) whose activity may be regulated by the former. Treatment of cells with interleukin-1 alpha, an agent known to elevate PLA2 levels, caused an increase in the THC response, supporting a role for this enzyme in the release reaction. Direct evidence, by immunoblotting, for the activation and phosphorylation of PLA2 by THC was also obtained. In summary, the evidence presented in this report indicates that THC-induced arachidonic acid release occurs through a series of events that are consistent with a receptor-mediated process involving the stimulation of one or more phospholipases.

Tuberculosis control strategies: the cost of particulate respirators

OBJECTIVE

To assess the cost of the mandatory use of high-efficiency particulate respirators to treat patients with known or suspected tuberculosis.

DESIGN

A questionnaire was used to determine the number of high-efficiency particulate respirators required and the number of cases of tuberculosis in employees that could potentially be prevented. Indirect costs included the training and fitness testing of employees. The clinical efficacy of respirators is not known. To provide a best-case scenario, it was assumed that the respirators could prevent as many as 25% of tuberculosis cases in health care workers.

SETTING

159 acute care facilities administered by the Department of Veterans Affairs.

PARTICIPANTS

Quality improvement, infection control, and employee health specialists.

MEASUREMENTS

Cost of the respirators compared with their maximum predicted efficacy.

RESULTS

The use of the respirators would cost $7 million per case of tuberculosis prevented and $100 million per life saved.

CONCLUSIONS

High-efficiency particulate respirators are a costly means of trying to prevent tuberculosis. Costs could be reduced by reusing masks or by restricting the number of health care workers allowed to have contact with potentially infectious patients. As the health care budget undergoes further restrictions, specific means of accommodating the cost of new regulations must be found.

G-protein mediation of cannabinoid-induced phospholipase activation

The release of arachidonic acid from mouse peritoneal and S49 cells induced by delta 1-tetrahydrocannabinol was found to be altered by prior exposure of the cells to either pertussis toxin or cholera toxin. The stable analogs of GTP and GDP, GTP-gamma-S and GDP-beta-S, were also effective in changing the extent of arachidonate release in saponin-treated cells. GDP-beta-S essentially abolished the THC response, while GTP-gamma-S showed effects mainly on vehicle-treated cells. The cataleptic action of THC in intact mice which is mediated by eicosanoids was also attenuated by pertussis toxin pretreatment. It is suggested that the THC receptor is coupled to phospholipases through one or more G-proteins and that adenylate cyclase probably does not have a role in this mechanism.

Elevation of brain prostaglandin E2 levels in rodents by delta 1-tetrahydrocannabinol

An isotopic dilution procedure using specific prostaglandin E2 (PGE2) brain receptors was utilized to determine the changes in brain PGE2 levels subsequent to drug exposure. Delta-1-tetrahydrocannabinol (delta 1-THC) stimulated PGE2 synthesis resulting in increased brain concentrations when compared with vehicle treated rats and mice. Indomethacin markedly inhibited the delta 1-THC elevated rise in PGE2 levels presumably by inhibition of prostaglandin synthetase. The delta 1-THC-induced increase in PGE2 brain levels was also suppressed by i.v. administered rabbit PGE2-antiserum. This suggests that one of the sites of delta 1-THC action is extracerebral and from here a portion of the released prostaglandins are transported to the brain. These results add further support to previous data that delta 1-THC given orally results in an increase in brain PGE2 levels.

Detection of cannabinoid receptors by photoaffinity labelling

A novel [125I]-labelled photoaffinity ligand designed to detect cannabinoid binding sites has been used in mouse brain preparations and in cultured S49 mouse lymphoma cells. The ligand, 2-iodo-5'-azido-delta 8-THC, shows a high affinity for sites in both brain (Kd = 5.60 pM) and whole cell (Kd = 9.38 pM) systems. Photolabelling studies with brain samples revealed the existence of four ligand-protein adducts, of estimated molecular weights 85.5, 62.1, 30.0 and 25.5 kDa, that were diminished by prior exposure to 8 microM THC. A similar study with S49 cells gave adducts with apparent molecular weights of 62.1, 34.4, 16.9 and 13.5 kDa. The ligand produces a typical cannabinoid cataleptic response in mice suggesting that possibly one or more of the binding sites may be involved in some of the receptor mediated actions of THC.

Appropriateness of admissions and discharges among readmitted patients

This study examined the relationships between appropriateness of readmission within two weeks of discharge and appropriateness of previous admission and discharge, bed section, type of readmission, and patient demographic, medical condition, and hospital stay characteristics. Using the Department of Veterans Affairs (VA) Patient Treatment File and medical records, 445 readmissions to a highly affiliated midwestern VA Medical Center in fiscal year 1984 were examined. Appropriateness was determined by four trained medical record abstractors using InterQual admission and discharge standards. Type of readmission was based on a pilot-tested flowchart. Appropriateness of readmission was significantly associated with that of the previous admission and discharge, with the relationship varying by admission, discharge, and readmission bed sections. Reasons for inappropriate admissions, discharges, and readmissions also varied by bed section. For the majority of inappropriate readmissions, there was clear written evidence in the medical record during the previous hospital stay that the patient was directed to return for readmission. Inappropriate readmissions were more likely than appropriate readmissions to have a primary diagnosis of neoplasm or digestive disorder. These results indicate the importance of examining both the operational efficiencies during the previous admission and the clinical criteria for admitting, discharging, and readmitting patients in assessing the appropriateness of readmissions.

Antagonism to the actions of platelet activating factor by a nonpsychoactive cannabinoid

A recent report from our laboratory gave evidence showing that tetrahydrocannabinol (THC)-7-oic acid has antinociceptive activity in the mouse. We also pointed out that this substance, which is a major metabolite of THC in most species including humans, is probably responsible for the well known analgesic properties of the parent drug. The present report contains findings that suggest THC-7-oic acid may have considerable activity as an antagonist to platelet activating factor, which may also explain the known properties of THC as a bronchodilator, antipyretic and antirheumatic agent. In the mouse ear edema test, THC-7-oic acid appeared to be about as efficacious as phenidone; however, its potency was less than either phenidone or indomethacin. When compared with the parent drug, THC, in the platelet activating factor-induced paw edema assay, it acted more quickly and produced a greater reduction of edema. This is consistent with the possibility that THC must be metabolized to the 7-oic acid for activity to be seen. Its activity in preventing platelet activating factor-induced mortality was comparable to naproxen. In vitro studies suggest that THC-7-oic acid can inhibit both cyclooxygenase and 5-lipoxygenase activities in intact cells.

Immunization against prostaglandins reduces delta 1-tetrahydrocannabinol-induced catalepsy in mice

Immunization of mice with a thyroglobulin-prostaglandin E2 (PGE2) conjugate produced animals with measurable blood levels of anti-PGE2 antibodies. When these mice were challenged with delta 1-tetrahydrocannabinol (THC) (20 mg/kg), they showed a greatly diminished cataleptic response as compared with control animals. This observation further supports a hypothesis on the mechanism of action of THC in which eicosanoids, such as PGE2, are early mediators. Based on the likelihood that antibodies were not present in the central nervous system, it is suggested that the initial site of action of THC may be at one or more peripheral locations. The transport of peripheral PGE2 or other eicosanoids to the brain would result in the eventual manifestation of THC action at this site.

Cannabinoids and pain responses: a possible role for prostaglandins

The principal metabolite of delta 1-THC, delta 1-THC-7-oic acid exhibits significant analgesic action in the mouse hot plate test. The parent delta 1-THC has a similar effect when measured at later time points; however, 10 min after drug administration, a pronounced hyperalgesia is seen. This hyperalgesia can be inhibited by prior administration of either indomethacin or delta 1-THC-7-oic acid, presumably because of their ability to inhibit eicosanoid synthesis. Administration of prostaglandin E2 (PGE2), at doses that were a small fraction of the delta 1-THC given, resulted in a strong hyperalgesic response. Unlike delta 1-THC, the metabolite does not produce a cataleptic state in the mouse, which eliminates this as a basis for the hot plate response. The evidence presented is consistent with a mechanism in which the metabolite inhibits eicosanoid synthesis whereas the parent drug elevates tissue levels of prostaglandins.

A major metabolite of delta 1-tetrahydrocannabinol reduces its cataleptic effect in mice

The results described here demonstrate that THC-induced catalepsy in mice can be substantially inhibited by the prior administration of delta 1-THC-7-oic acid, the major metabolite of THC in most species including humans. This raises the possibility that the intensity and duration of action of THC may depend to a large degree on the levels of this metabolite at the sites of action.

Prostaglandins and cannabis XV. Comparison of enantiomeric cannabinoids in stimulating prostaglandin synthesis in fibroblasts

Stereospecificity has been reported for a number of actions of the cannabinoids in a variety of systems. In the present report, we have shown that this effect can also be demonstrated when human lung fibroblasts in monolayer culture are stimulated by cannabinoids to produce prostaglandin E2 (PGE2). Three enantiomeric pairs of cannabinoids, (+) and (-)-delta 1-tetrahydrocannabinol (THC), (+) and (-)-delta 6-THC and (+) and (-)-delta 6-dimethylheptyl (DMH) THC were tested. In each case the (-) isomer was significantly more potent in agreement with the findings of others using different systems. Interestingly, very little stereospecificity was found in fibroblasts when the release of arachidonic acid, the precursor of PGE2, was monitored. This suggests that cannabinoids may act at several sites within the cell some of which show comparatively greater stereoselectivity for these agonists.

Effects of cannabinoids on the activities of mouse brain lipases

Cannabinoids were found to augment phospholipase activities and modify lipid levels of mouse brain synaptosomes, myelin and mitochondria. Delta-1-tetra-hydrocannabinol (delta 1-THC) and several of its metabolites induced a dose-dependent (0.32-16 microM) stimulation of phospholipase A2 (PLA2) activity resulting in the increased release of free arachidonic acid from exogenous [1-14C]phosphatidylcholine (PC). The potencies of the cannabinoids in modulating PLA2 activity were approximately of the order: 7-OH-delta 1-THC greater than delta 1-THC greater than 7-oxo-delta 1-THC greater than delta 1-THC-7-oic acid = 6 alpha OH-delta 1-THC much greater than 6 beta-OH-delta 1-THC. The hydrolysis of phosphatidylinositol (PI) by synaptosomal phospholipase C (PLC) was enhanced significantly by delta 1-THC and promoted diacylglyceride levels by greater than 100 percent compared to control values. In contrast, arachidonate was the major product resulting from phospholipase activities of a 20,000 g pellet. Synaptosomal diacylglyceride lipase activity was inhibited by delta 1-THC. [1-14C]Arachidonic acid was readily incorporated into subcellular membrane phospholipids and after exposure to cannabinoids led to diminished phosphoglyceride levels and concomitant increases in released neutral lipid products. These data suggest that cannabinoids control phospholipid turnover and metabolism in mouse brain preparations by the activation of phospholipases and, through this mechanism, may exert some of their effects.

Prostaglandins and cannabis--XVI. Antagonism of delta 1-tetrahydrocannabinol action by its metabolites

Prior exposure of cells in vitro to delta 1-tetrahydrocannabinol-7-oic acid (delta 1-THC-7-oic acid) reduced the degree of stimulation of prostaglandin synthesis incurred by subsequent treatment with delta 1-THC. The site of action of this inhibitory effect seemed to be on cyclooxygenase and not at the earlier step involving the phospholipase-mediated release of arachidonic acid. delta 1-THC-7-oic acid is a major metabolite of delta 1-THC and has no psychoactivity in humans. Our findings raise the possibility, however, that it may influence the in vivo activities of delta 1-THC by antagonizing its stimulatory action on cellular prostaglandin synthesis.

Prostaglandins and cannabis XIV. Tolerance to the stimulatory actions of cannabinoids on arachidonate metabolism

The stimulation of prostaglandin E2 synthesis by delta 1-tetrahydrocannabinol in cultured cells is rapidly diminished by successive exposures to the drug at 24-hr intervals. Cannabidiol and cannabicyclol, two other constituents of cannabis, also displayed this in vitro tolerance effect. The phenomenon could, in addition, be observed by measuring the release of arachidonic acid from these cells, suggesting that the site of action of the cannabinoids is at one or more of the lipases that are believed to control prostaglandin synthesis under most conditions. Tolerance to cannabinoid action has been reported for a variety of in vivo parameters; thus, this in vitro system exhibits similar behavior and may, therefore, be a good model for studies on the molecular mechanisms involved in tetrahydrocannabinol action.

Prostaglandins and cannabis--XIII. Cannabinoid-induced elevation of lipoxygenase products in mouse peritoneal macrophages

The phospholipases controlling the release of arachidonic acid in mouse peritoneal macrophages have been shown to be stimulated by the natural psychoactive cannabinoids. A close correlation was observed between the potencies of these substances in elevating arachidonate levels in vitro and the reported activities in a behavioral assay in monkeys and in producing a "high" in humans. The order of activity with the macrophages was delta 1-tetrahydrocannabinol (delta 1-THC) greater than 7-OH-delta 1-THC greater than 6 alpha-OH-delta 1-THC greater than 6 beta-delta 1-THC much greater than delta 6-THC-7-oic acid. It is suggested that this effect, which has now been shown in several diverse cell types, may serve as a model for studying the mechanism of action of THC.

Stimulation of sphingomyelin hydrolysis by cannabidiol in fibroblasts from a Niemann-Pick patient

The hydrolysis of sphingomyelin in cells derived from a Niemann-Pick patient was studied using both a labelled precursor and measurement of endogenous levels. In vitro exposure of the cells to cannabidiol resulted in a large decrease in both the relative and absolute amounts of this lipid; the drug had a smaller effect on normal fibroblasts. Cannabidiol has been tested in the clinic as an antiepileptic agent with some success; our findings suggest that it may also be useful in relieving the symptoms associated with Niemann-Pick disease.

Stimulation of prostaglandin synthesis in WI-38 human lung fibroblasts following inhibition of phospholipid acylation by p-hydroxymercuribenzoate

The release of arachidonic acid and its metabolites, prostaglandin E2 and thromboxane A2, from WI-38 human lung fibroblasts was modulated by p-hydroxymercuribenzoate. Exposure to the inhibitor resulted in a dose-dependent decrease in [1-14C]arachidonic acid uptake and incorporation into phospholipids and neutral lipid pools. Activities of lung fibroblast arachidonyl-CoA synthetase and lysolecithin acyltransferase were inhibited by 100 microM p-hydroxymercuribenzoate. [14C]Arachidonic acid labelled fibroblasts exhibited an increased release of [14C]arachidonate and [14C]prostaglandin E2 of 54% and 112%, respectively, when exposed to 100 microM of inhibitor. The stimulatory effects of 8.0 microM delta 1-tetrahydrocannabinol on arachidonate release and prostaglandin E synthesis (Burstein, S., Hunter, S.A., Sedor, C. and Shulman, S. (1982) Biochem. Pharmacol. 31, 2361-2365) were modified by the inclusion of inhibiting agent, resulting in a 608% stimulation in arachidonic acid release, while prostaglandin E2 and thromboxane A2 synthesis increased 894% and 390%, respectively, over levels obtained by untreated cells. The levels of arachidonate metabolites were altered by inhibitor when compared to cells treated with cannabinoid alone. No significant inhibition by delta 1-tetrahydrocannabinol was found on arachidonic uptake in these cells. In unlabelled studies, p-hydroxymercuribenzoate resulted in a profound, dose-dependent stimulation of prostaglandin E synthesis of 1490% at 150 microM inhibitor concentration. These results provide evidence that free arachidonate is reincorporated via acylation, thereby implicating this pathway as a possible control mechanism for the synthesis of arachidonic acid metabolites.

Prostaglandins and cannabis. XII. The effect of cannabinoid structure on the synthesis of prostaglandins by human lung fibroblasts

Earlier findings indicated that several other cannabinoids in addition to delta 1-tetrahydro-cannabinol (THC) were able to stimulate the synthesis of prostaglandins in cell culture systems. The present study was initiated to delineate the structural requirements for this effect within the cannabinoid series. Among the primary cannabinoids, we found that the trend was for more planar structures to show greater activity. In the case of THC metabolites, the order of activity was delta 1-THC greater than 7-oxo-delta 1, 6-THC greater than 7-OH-delta 1-THC greater than 3"-OH-delta 1-THC = 6 beta-OH-delta 1-THC = 6 alpha-OH-delta 1-THC greater than delta 1, 6-THC-7-oic acid. The latter sequence compares favorably with the available data on the behavioral assay in the rhesus monkey and the subjective "high" in humans. We also observed a good correlation between the release of arachidonic acid and the production of prostaglandin E, over a series of eight cannabinoids. This gives further support that the site of action in this effect is the elevation of activity of the phospholipase(s) responsible for supplying precursor arachidonic acid for prostaglandin synthesis.

Prostacyclin production by vein grafts in the arterial circulation: a study in rats

The in vitro production of prostacyclin by vein grafts was measured using vascular rings followed by radioimmunoassay of the medium. The grafts were prepared by interposing a segment of epigastric vein in a gap in the ipsilateral femoral artery of the rat. Measurements made over a period of 1 to 42 days showed a progressive rise from venous levels (less than 0.2 ng/ml) to values close to the arterial controls (10.9 +/- 2.2 ng/ml). This deficiency of prostacyclin synthesis during the "arterialization" of the graft may account for some of the early failures which can occur in vein grafting and suggests the possibility of pharmacological intervention to improve the success rate.

Prostaglandins and cannabis--IX. Stimulation of prostaglandin E2 synthesis in human lung fibroblasts by delta 1-tetrahydrocannabinol

Preliminary data [S. Burstein and S. A. Hunter, Biochem. Pharmac. 27, 1275 (1978)] showed that cannabinoids at levels of 1 microM or greater elevated the concentrations of prostaglandins in cell culture models. Further study [S. Burstein and S. A. Hunter, J. clin. Pharmac. 21, 240S (1981)] led to the suggestion that this effect was due to a stimulation of phospholipase A2 resulting in the release of free arachidonic acid which was then partly converted into the prostaglandin(s) normally synthesized by the particular target system. The present report gives detailed data on the cannabinoid-induced synthesis of prostaglandin E2 by te WI-38 fibroblast derived from human lung. The effect could be blocked by pretreatment with mepacrine, a phospholipase inhibitor, and aspirin, a cyclooxygenase inhibitor. These findings lend support to the hypothesis that some of the in vivo actions of the cannabinoids are due to modulations in prostaglandin synthesis at various tissue sites.

Prostaglandins and cannabis--VIII. Elevation of phospholipase A2 activity by cannabinoids in whole cells and subcellular preparations

The previously reported release of arachidonic acid by THC has now been demonstrated in murine Leydig cells and WI-38 human lung fibroblasts showing the generality of the effect. The release reaction could be antagonized by phospholipase A2 inhibitors such as quinacrine and quinine, suggesting that THC can stimulate the activity of this enzyme. Further evidence for this possibility was obtained by demonstrating the release effect on a subcellular fraction which contained the phospholipase A2 activity. The stimulation of this enzyme could have profound effects on prostaglandin synthesis and/or on the integrity of various membrane structures.

Retrospective utilization review as a focused method of evaluation

Retrospective UR may be the method of choice if, in general, a problem is best addressed through a sampling of completed records. Note that this type of review is currently different from a patient care evaluation or audit. Such studies usually compare optimum standards of care for a diagnosis with the actual care delivered to patients as documented in their records. Retrospective UR, however, may be used to focus on a problem in the delivery of care that has previously been identified. As such, it can be an effective component of a total quality assurance program.

The nature of the inhibition of cholesterol esterase by delta 1-tetrahydrocannabinol

An improved assay for cholesterol esterase based on the use of fatty acid radiolabelled cholesterol esters has been developed. The method was used to demonstrate the effects of delta 1-tetrahydrocannabinol on a crude Leydig cell esterase preparation and on crystalline pancreatic esterase. Both enzymes were inhibited and the Km values determined (6.6 mumol/1 for the Leydig cell esterase and 6.25 mumol/1 for the pancreatic enzyme). While the former exhibited a mixed type of inhibition, the latter clearly was competitive.

Cannabinoid inhibition of rat luteal cell progesterone synthesis

Progesterone production by isolated rat luteal cells was inhibited by exposure to various cannabinoids in concentrations from 3.0--16.0 microM. The available evidence points to the cleavage of cholesterol esters as the site of inhibition.