Cutting edge: lipoxins rapidly stimulate nonphlogistic phagocytosis of apoptotic neutrophils by monocyte-derived macrophages

Lipoxins (LX) are lipoxygenase-derived eicosanoids generated during inflammation. LX inhibit polymorphonuclear neutrophil (PMN) chemotaxis and adhesion and are putative braking signals for PMN-mediated tissue injury. In this study, we report that LXA4 promotes another important step in the resolution phase of inflammation, namely, phagocytosis of apoptotic PMN by monocyte-derived macrophages (Mphi). LXA4 triggered rapid, concentration-dependent uptake of apoptotic PMN. This bioactivity was shared by stable synthetic LXA4 analogues (picomolar concentrations) but not by other eicosanoids tested. LXA4-triggered phagocytosis did not provoke IL-8 or monocyte chemoattractant protein-1 release. LXA4-induced phagocytosis was attenuated by anti-CD36, alphavbeta3, and CD18 mAbs. LXA4-triggered PMN uptake was inhibited by pertussis toxin and by 8-bromo-cAMP and was mimicked by Rp-cAMP, a protein kinase A inhibitor. LXA4 attenuated PGE2-stimulated protein kinase A activation in Mphi. These results suggest that LXA4 is an endogenous stimulus for PMN clearance during inflammation and provide a novel rationale for using stable synthetic analogues as anti-inflammatory compounds in vivo.

ASCT2/SLC1A5 controls glutamine uptake and tumour growth in triple-negative basal-like breast cancer

Alanine, serine, cysteine-preferring transporter 2 (ASCT2; SLC1A5) mediates uptake of glutamine, a conditionally essential amino acid in rapidly proliferating tumour cells. Uptake of glutamine and subsequent glutaminolysis is critical for activation of the mTORC1 nutrient-sensing pathway, which regulates cell growth and protein translation in cancer cells. This is of particular interest in breast cancer, as glutamine dependence is increased in high-risk breast cancer subtypes. Pharmacological inhibitors of ASCT2-mediated transport significantly reduced glutamine uptake in human breast cancer cell lines, leading to the suppression of mTORC1 signalling, cell growth and cell cycle progression. Notably, these effects were subtype-dependent, with ASCT2 transport critical only for triple-negative (TN) basal-like breast cancer cell growth compared with minimal effects in luminal breast cancer cells. Both stable and inducible shRNA-mediated ASCT2 knockdown confirmed that inhibiting ASCT2 function was sufficient to prevent cellular proliferation and induce rapid cell death in TN basal-like breast cancer cells, but not in luminal cells. Using a bioluminescent orthotopic xenograft mouse model, ASCT2 expression was then shown to be necessary for both successful engraftment and growth of HCC1806 TN breast cancer cells in vivo. Lower tumoral expression of ASCT2 conferred a significant survival advantage in xenografted mice. These responses remained intact in primary breast cancers, where gene expression analysis showed high expression of ASCT2 and glutamine metabolism-related genes, including GLUL and GLS, in a cohort of 90 TN breast cancer patients, as well as correlations with the transcriptional regulators, MYC and ATF4. This study provides preclinical evidence for the feasibility of novel therapies exploiting ASCT2 transporter activity in breast cancer, particularly in the high-risk basal-like subgroup of TN breast cancer where there is not only high expression of ASCT2, but also a marked reliance on its activity for sustained cellular proliferation.

Pubertal changes in daytime sleepiness

Nineteen children (8 girls, 11 boys) were evaluated in a total of 47 three-day sessions across three summers. Children were ranked according to Tanner's stages of secondary sexual characteristics. Nocturnal sleep was recorded from 2200 to 0800 hr each night. Multiple sleep latency tests were given at 2 hr intervals from 0930 each day. Nocturnal sleep time and REM sleep time remained constant across Tanner stages. Slow wave sleep time declined progressively across Tanner stages, with a 40% reduction from prepuberty to maturity. Daytime sleepiness was significantly greater in subjects at Tanner stages 3 and 4 than at Tanner stages 1 and 2. Subjects at Tanner stage 5 tended to be as sleepy as Tanner stage 3 and 4 subjects but did not differ significantly from the less mature subjects. No gender differences were found in daytime sleepiness for children at similar Tanner stages. More mature children were significantly sleepier at 1330 and 1530 than in the late afternoon and evening.

Sphingosine 1-phosphate released from platelets during clotting accounts for the potent endothelial cell chemotactic activity of blood serum and provides a novel link between hemostasis and angiogenesis

Recent studies have identified factors responsible for angiogenesis within developing tumors, but mediators of vessel formation at sites of trauma, injury, and wound healing are not clearly established. Here we show that sphingosine 1-phosphate (S1P) released by platelets during blood clotting is a potent, specific, and selective endothelial cell chemoattractant that accounts for most of the strong endothelial cell chemotactic activity of blood serum, an activity that is markedly diminished in plasma. Preincubation of endothelial cells with pertussis toxin inhibited this effect of S1P, demonstrating the involvement of a Galphai-coupled receptor. After S1P-induced migration, endothelial cells proliferated avidly and differentiated forming multicellular structures suggestive of early blood vessel formation. S1P was strikingly effective in enhancing the ability of fibroblast growth factor to induce angiogenesis in the avascular mouse cornea. Our results show that blood coagulation initiates endothelial cell angiogenic responses through the release of S1P, a potent endothelial cell chemoattractant that exerts its effects by activating a receptor-dependent process.

Monocytes harbour replication-competent, non-latent HIV-1 in patients on highly active antiretroviral therapy

OBJECTIVE

To determine whether HIV-1 can be recovered from blood monocytes as well as resting, memory CD4 T lymphocytes of patients on highly active antiretroviral therapy (HAART) with undetectable plasma viraemia and whether infection is active or latent.

DESIGN

Five patients with plasma HIV-1-RNA levels of less than 500 copies/ml for at least 3 months and less than 50 copies/ml at the time of sampling were initially selected, followed by an additional five patients with viral loads of less than 50 copies/ml for 3 months or more.

METHODS

Monocytes were isolated from blood by plastic adherence, then further purified by a second adherence step or CD3 depletion before co-culture with CD8-depleted donor peripheral blood mononuclear cells. Virus isolates were examined for mutations conferring resistance to reverse transcriptase or protease inhibitors and for genotype. The highly purified monocytes were also analysed for the presence of proviral and unintegrated viral DNA and multiply spliced (MS) viral mRNA by polymerase chain reaction.

RESULTS

Virus was recovered from monocytes of five patients. Sequencing of the recovered viruses did not reveal multiple drug resistance, and was consistent with a non-syncytium-inducing/CCR5 phenotype. Proviral DNA was detectable in monocytes from all subjects, and unintegrated HIV-1 DNA and MS RNA was found in four out of five populations examined.

CONCLUSION

Recovery of replication-competent virus from some HAART patients indicates that monocytes can also harbour HIV-1. Detection of circular, viral DNA and spliced RNA, albeit at very low levels, in these cells suggests that their infection is recent and transcriptionally active rather than latent.

Sleep loss in young adolescents

Effects of one night's sleep loss on nocturnal sleep, performance, and sleepiness were evaluated in 12 subjects (8 boys, 4 girls) whose ages ranged from 11.7 to 14.6 years. The magnitude and direction of sleep stage changes after sleep loss were comparable to similar findings in older subjects. Performance test decrements occurred for two measures during sleep deprivation. The performance decrements appeared to be related to episodes of sleep during the performance tests. Subjective measures of sleepiness showed a significant increase during sleep loss, with a complete recovery to basal levels after one night of sleep. The subjective ratings of sleepiness during sleep loss also showed a marked short-term dependence on preceding activity levels. Multiple sleep latency tests showed a marked reduction of sleep onset latency from 0530 throughout the day of sleep loss. In contrast to the subjective measures, sleep latency test scores did not vary with activity levels during sleep loss and did not recover to basal levels until the afternoon of the first recovery day. In general, there were no marked differences in the sleep loss response of young adolescents as compared to published reports of sleep loss in older subjects.

Docosahexaenoic acid induces apoptosis in Jurkat cells by a protein phosphatase-mediated process

Docosahexaenoic acid (DHA) is an omega-3 fatty acid under intense investigation for its ability to modulate cancer cell growth and survival. This research was performed to study the cellular and molecular effects of DHA. Our experiments indicated that the treatment of Jurkat cells with DHA inhibited their survival, whereas similar concentrations (60 and 90 microM) of arachidonic acid and oleic acid had little effect. To explore the mechanism of inhibition, we used several measures of apoptosis to determine whether this process was involved in DHA-induced cell death in Jurkat cells. Caspase-3, an important cytosolic downstream regulator of apoptosis, is activated by death signals through proteolytic cleavage. Incubation of Jurkat cells with 60 and 90 microM DHA caused proteolysis of caspase-3 within 48 and 24 h, respectively. DHA treatment also caused the degradation of poly-ADP-ribose polymerase and DNA fragmentation as assayed by flow cytometric TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) assay. These results indicate that DHA induces apoptosis in Jurkat leukemic cells. DHA-induced apoptosis was effectively inhibited by tautomycin and cypermethrin at concentrations that affect protein phosphatase 1 (PP1) and protein phosphatase 2B (PP2B) activities, respectively, implying a role for these phosphatases in the apoptotic pathway. Okadaic acid, an inhibitor of protein phosphatase 2A, had no effect on DHA-induced apoptosis. These results suggest that one mechanism through which DHA may control cancer cell growth is through apoptosis involving PP1/PP2B protein phosphatase activities.

Child sexual abuse, poor parental care and adult depression: evidence for different mechanisms

BACKGROUND

Child sexual abuse (CSA) and poor parental care (neglect and institutional care) are associated with depression in adult life. Little is known about possible mechanisms underlying these associations.

AIMS

To examine the role of adult intimate-love relationships as differential mediators or moderators of the associations between CSA, poor parental care and adult depression.

METHOD

Sampling was carried out in two phases. In the first, questionnaires were sent to women aged 25-36 years in five primary care practices. Second-phase subjects for interview (n=198) were drawn from three strata defined on the basis of childhood adversities. Recalled childhood experiences and recent adult relationships and depression were assessed and rated independently. Frequencies of predictor and response variables, effect estimates and their confidence intervals were weighted back to the general population questionnaire sample.

RESULTS

The risk for depression associated with CSA was unaffected by quality of adult relationships, while the risk associated with poor parental care was substantially altered.

CONCLUSIONS

There may be different pathways linking CSA and poor parental care to adult depression.

Sleep habits of children and the identification of pathologically sleepy children

Sleep disorders and daytime sleepiness have been investigated only minimally in children. The sleep habits of 218 children, ages 10-13 years, were surveyed by a sleep habits questionnaire (SHQ). Our results demonstrate that total night time sleep on school nights begins to fall in early adolescence, whereas it remains relatively stable on non-school nights. Daytime sleepiness is not a common problem in this age group, in contrast to a college age population. We conclude that in adolescence chronic sleep deficits begin to occur which cumulatively affect later functioning. The potential use of the SHQ for depicting pathological sleepiness is also discussed.

Intellectual functioning and outcome of patients with severe psychotic illness randomised to intensive case management. Report from the UK700 trial

BACKGROUND

Little research has been carried out on the benefits of intensive case management (ICM) for people with borderline IQ and severe mental illness.

AIMS

To compare outcome and costs of care of patients with severe psychotic illness with borderline IQ to patients of normal IQ and to assess whether ICM is more beneficial for the former than for the latter.

METHOD

The study utilises data from the UK700 multi-centre randomised controlled trial of case management. The main outcome measure was the number of days spent in hospital for psychiatric reasons. Secondary outcomes were costs of care and clinical outcome.

RESULTS

ICM was significantly more beneficial for borderline-IQ patients than those of normal IQ in terms of reductions in days spent in hospital, hospital admissions, total costs and needs and increased satisfaction.

CONCLUSIONS

ICM appears to be a cost-effective strategy for a subgroup of patients with severe psychosis with cognitive deficits.

A review of instruments developed to measure outcomes for carers of people with mental health problems

OBJECTIVE

Community-based care for mental disorders places considerable burden on families and carers. Measuring their experiences has become a priority, but there is no consensus on appropriate instruments. We aimed to review instruments carers consider relevant to their needs and assess evidence for their use.

METHOD

A literature search was conducted for outcome measures used with mental health carers. Identified instruments were assessed for their relevance to the outcomes identified by carers and their psychometric properties.

RESULTS

Three hundred and ninety two published articles referring to 241 outcome measures were identified, 64 of which were eligible for review (used in three or more studies). Twenty-six instruments had good psychometric properties; they measured (i) carers' well-being, (ii) the experience of caregiving and (iii) carers' needs for professional support.

CONCLUSION

Measures exist which have been used to assess the most salient aspects of carers outcome in mental health. All require further work to establish their psychometric properties fully.

Reducing violence in severe mental illness: randomised controlled trial of intensive case management compared with standard care

OBJECTIVES

To establish whether intensive case management reduces violence in patients with psychosis in comparison with standard case management.

DESIGN

Randomised controlled trial with two year follow up.

SETTING

Four inner city community mental health services.

PARTICIPANTS

708 patients with established psychotic illness allocated at random to intervention (353) or control (355) group.

INTERVENTION

Intensive case management (caseload 10-15 per case manager) for two years compared with standard case management (30-35 per case manager).

MAIN OUTCOME MEASURE

Physical assault over two years measured by interviews with patients and case managers and examination of case notes.

RESULTS

No significant reduction in violence was found in the intensive case management group compared with the control group (22.7% v 21.9%, P=0.86).

CONCLUSIONS

Intensive case management does not reduce the prevalence of violence in psychotic patients in comparison with standard care.

Relatives of patients with severe psychotic illness: factors that influence appraisal of caregiving and psychological distress

BACKGROUND

Research shows considerable variability in the effect on relatives of patients' mental illness but the determinants of relatives' experience remain unclear. We investigated the influence of demographic, social and clinical characteristics on relatives' experience when conceptualised using a stress-appraisal-coping paradigm.

METHODS

Our sample was drawn from relatives of patients recruited to the UK700 case management study (n = 154). Demographic, social and clinical data were collected from patients, and relatives completed the Experience of Caregiving Inventory and the General Health Questionnaire. We predicted that patients' symptomatology in particular would influence relatives' experience, and that relatives who appraised caregiving more negatively and less positively would experience greater psychological distress.

RESULTS

Linear regression analyses revealed that relatives' appraisal was not predicted by patients' symptomatology. Instead, relatives appraised caregiving more negatively if the patient was unemployed or younger, and less positively if the patient had been ill for longer or had poorer social functioning. Little of the variance in appraisal was explained by these variables, however. Consistent with the stress-coping model, relatives' negative appraisal was a strong predictor of psychological distress and accounted for a substantial proportion of its variance. Positive appraisal did not predict psychological distress, however. None of the demographic, social or clinical characteristics tested had any significant effect on relatives' psychological distress once appraisal was adjusted for. There was an unexpected positive correlation between the two appraisal scales, with relatives who appraised caregiving more negatively also appraising it more positively.

CONCLUSIONS

Our results support a stress-coping model of caregiving but further research is required to determine more influential predictors of relatives' appraisal. Our findings indicate that interventions aimed at patients' social functioning and relatives' negative appraisal of caregiving may assist in reducing relatives' psychological distress.

Response of 33 UK patients with infantile-onset Pompe disease to enzyme replacement therapy

BACKGROUND

Enzyme replacement therapy (ERT) for infantile-onset Pompe disease has been commercially available for almost 10 years. We report the experience of its use in a cohort treated at three specialist lysosomal treatment centres in the UK.

METHODS

A retrospective case-note review was performed, with additional data being gathered from two national audits on all such patients treated with ERT. The impact on the outcome of various characteristics, measured just prior to the initiation of ERT (baseline), was evaluated using logistic regression.

RESULTS

Thirty-three patients were identified; 13/29 (45%) were cross-reactive immunological material (CRIM) negative, and nine were immunomodulated. At baseline assessment, 79% were in heart failure, 66% had failure to thrive and 70% had radiological signs of focal pulmonary collapse. The overall survival rate was 60%, ventilation-free survival was 40% and 30% of patients were ambulatory. Median follow-up of survivors was 4 years, 1.5 months (range 6 months to 13.5 years). As with previous studies, the CRIM status impacted on all outcome measures. However, in this cohort, baseline failure to thrive was related to death and lack of ambulation, and left ventricular dilatation was a risk factor for non-ventilator-free survival.

CONCLUSION

The outcome of treated patients remains heterogeneous despite attempts at immunomodulation. Failure to thrive at baseline and left ventricular dilation appear to be associated with poorer outcomes.

Diagnostic testing for serious bacterial infections in infants aged 90 days or younger with bronchiolitis

OBJECTIVES

To describe the different laboratory tests that are performed on young infants aged 90 days or younger with bronchiolitis and to identify historical and clinical predictors of infants on whom laboratory tests are performed.

DESIGN

Cross-sectional study whereby information was obtained by retrospective review of medical records from November through March 1992 to 1995 of all infants with a clinical diagnosis of bronchiolitis.

SETTING

Urban pediatric emergency department.

PATIENTS

Two hundred eleven consecutive infants aged 90 days or younger (median age, 54 days) with 216 episodes of bronchiolitis.

MAIN OUTCOME MEASURES

Historical and clinical data on each infant in addition to laboratory data that included a white blood cell count, urinalysis, and blood, urine, and cerebrospinal fluid cultures.

RESULTS

Two or more laboratory tests (not including chest radiographs) were obtained in 48% of all infants and 78% of febrile infants. Of the 91 infants with a history of a temperature of 38.0 degrees C or more or temperature on presentation of 38.0 degrees C or more, white blood cell counts were obtained in 77%, blood cultures in 75%, urinalyses in 53%, urine cultures in 60%, and analyses-cultures of cerebrospinal fluid in 47%. Febrile infants were 10 times more likely to get at least 2 laboratory tests than afebrile infants (P<.01). All 6 studies were done in 42 (58%) of 72 febrile infants compared with 7 (16%) of 43 afebrile infants (P<.001). Multiple logistic regression analysis identified a history of a temperature of 38.0 degrees C or more or temperature on presentation of 38.0 degrees C or more (odds ratio [OR] 10.0; 95% confidence interval [CI], 4.8%-21.0%; P<.001), oxygen saturation less than 92% on presentation (OR, 4.7; 95% CI, 1.9%-12.1%; P<.01), and history of apnea (OR, 0.1; 95% CI, 0.02-0.35; P<.001) as significant clinical predictors of whether laboratory studies were obtained. History of preterm gestation, aged younger than 28 days, previous antibiotic use, and presence of otitis media were not associated with obtainment of laboratory studies. No cases of bacteremia, urinary tract infection, or meningitis were found among all infants with bronchiolitis who had blood, urine, and/or cerebrospinal fluid cultures.

CONCLUSION

There is wide variability in the diagnostic testing of infants aged 90 days or younger with bronchiolitis. The risks of bacteremia, urinary tract infection, and meningitis in infants with bronchiolitis seems to be low. History or a documented temperature of 38.0 degrees C or more; oxygen saturation of less than 92%, and history of apnea were associated with laboratory testing for bacterial infections.

Suicidal behaviour in psychosis: prevalence and predictors from a randomised controlled trial of case management: report from the UK700 trial

BACKGROUND

It is unclear whether intensive case management influences the prevalence of suicidal behaviour in patients with psychosis.

AIMS

To compare the effect of intensive case management and standard care on prevalence of suicidal behaviour in patients with chronic psychosis.

METHOD

Patients with established psychosis (n = 708) were randomised either to intensive case management or to standard care. The prevalence of suicidal behaviour was estimated at 2-year follow-up and compared between treatment groups. Suicide attempters and non-attempters were compared on multiple socio-demographic and clinical variables to identify predictors of suicidal behaviour.

RESULTS

There was no significant difference in prevalence of suicidal behaviour between treatment groups. Recent attempts at suicide and multiple recent hospital admissions best predicted future attempts.

CONCLUSIONS

Intensive case management does not appear to influence the prevalence of suicidal behaviour in chronic psychosis. Predictors identified in this study confirm some previous findings.

Fundamental cryobiology of human hematopoietic progenitor cells. I: Osmotic characteristics and volume distribution

While methods for the cryopreservation of hematopoietic stem cells are well established, new sources of progenitor cells, such as umbilical cord blood, fetal tissue, and ex vivo expanded progenitor cells, may require refined protocols to achieve optimal recovery after freezing. To predict optimal protocols for cryopreservation of human hematopoietic progenitors, knowledge of fundamental cryobiological characteristics including cell osmotic characteristics, water and cryoprotectant permeability coefficients of cell membrane, and activation energies of these coefficients is required. In this study, we used CD34+CD33- cells isolated from human bone marrow as hematopoietic progenitor cell models/representatives to study the osmotic characteristics of the progenitor cells. Volume distribution and osmotic behavior of the CD34+CD33- cells were determined using two different methods: (a) a shape-independent electronic sizing technique and (b) a shape-dependent optical image analysis. The cell diameter was measured to be 8.2 +/- 1.1 microns (mean +/- SD, n = 1,091,475, the number of donors = 8) using the electronic sizing technique or 8.7 +/- 1.2 microns (mean +/- SD, n = 1508, the number of donors = 6) by image analysis at initial (isotonic) osmolality, 325 mosm/kg. The cell volume change was measured after the cells were exposed and equilibrated to different anisosmotic conditions. The cell volume was found to be a linear function of the reciprocal of the extracellular osmolality (Boyle van't Hoff plot) ranging from 163 to 1505 mosm/kg. The volume fraction of intracellular water which is osmotically active was determined to be 79.5% of the cell volume. It was concluded that human CD34+CD33- cells osmotically behave as ideal osmometers. This information coupled with cell water and cryoprotectant permeability coefficients as well as their activation energies (to be determined in the ongoing research projects) will be used to design optimum conditions for cryopreservation of human hematopoietic progenitor cells.

Phorbol ester-induced priming of superoxide generation by phosphatidic acid-stimulated neutrophils and granule-free neutrophil cytoplasts

This study was undertaken to examine the mechanisms involved in polymorphonuclear leukocyte superoxide release stimulated by exogenous phosphatidic acid (PA). Unlike the immediate burst of superoxide release affected by membrane-permeable dioctanoylglycerol (DiC8-DAG), dioctanoyl phosphatidic acid (DiC8-PA) induced superoxide release after a lag period of 5-20 min. This period was considerably reduced or eliminated when cells were primed by substimulatory levels of phorbol myristate acetate (PMA). Granule-depleted neutrophil cytoplasts also responded to DiC8-PA with a burst of superoxide generation. Activation of the cytoplast superoxide generating system in response to DiC8-PA was also significantly faster after cells had been preexposed to substimulatory levels of PMA, indicating that at least a portion of the priming mechanism was independent of PMA-induced degranulation. To further examine the potential mechanism of PMA priming of responses to PA, we evaluated the activity of neutrophil ecto-phosphatidic acid phosphohydrolase (ecto-PA phosphohydrolase), which generates diacylglycerol from exogenous PA. PMA priming had no discernable effect on the activity of this enzyme. In addition, propranolol, an inhibitor of PA phosphohydrolase, did not selectively inhibit PMA priming of neutrophil responses to DiC8-PA, indicating that priming did not result from acceleration of DiC8-PA hydrolysis. We therefore investigated the possibility that activation of protein kinase C was the basis of the primed response. Several semiselective protein kinase C inhibitors (calphostin C, H-7, and acylmethylglycerol) inhibited DiC8-DAG- and DiC8-PA-induced superoxide release as well as PMA-primed responses to approximately the same extent. These results are consistent with the hypothesis that neutrophil responses to phosphatidate are mediated by diglyceride generated by the action of ecto-PA phosphohydrolase. PMA priming does not result from increased catalytic activity of ecto-PA phosphohydrolase but rather seems to result from potentiation of an intermediate involved in the cells' response to multiple stimuli.

Prevalence and characteristics of patients with severe mental illness and borderline intellectual functioning. Report from the UK700 randomised controlled trial of case management

BACKGROUND

Low cognitive ability and developmental delays have been implicated in the causation of mental illness.

AIMS

To examine the prevalence, socio-demographic characteristics, psychopathology and social functioning profiles of people with low intelligence and recurrent psychotic illness.

METHOD

A multi-centre randomised controlled trial of case management provided the opportunity to explore associations between mental illness and borderline intellectual functioning (assessed using the National Adult Reading test).

RESULTS

Overall prevalence of borderline intelligence was 18%. Significant positive associations were shown with: being Black Caribbean; having a father who worked in a manual occupation; lower educational achievement; having had special education; longer course of illness. Those with borderline intelligence had greater disability and were more likely to suffer extrapyramidal side-effects and show evidence of negative symptoms. Educational achievement, history of special education and social class were the best socio-demographic predictors of intellectual level.

CONCLUSIONS

Many patients who attend generic psychiatric services have considerable intellectual deficits. This may lead to difficulties in other domains of adaptive functioning, and merits further investigation as well as clinical vigilance.

Effects of acute marijuana smoking on pulse rate and mood states in women

The effects of marijuana cigarette (1.8% THC) smoking on pulse rate and mood were studied under double-blind placebo-controlled conditions in 28 adult female volunteers during the follicular, luteal, and ovulatory phases of the menstrual cycle. Statistically significant increases in pulse rate, subjective levels of intoxication, and the POMS confusion factor occurred after marijuana smoking. However, no statistically significant differences for any measure were observed following marijuana smoking as a function of menstrual cycle phase. Subjects with a past history of intermittent marijuana use (five or less times weekly) had significantly higher pulse rates, subjective levels of intoxication, and POMS confusion factor scores than did subjects with a past history of regular (six or more times weekly) marijuana use. Persistence of marijuana-induced changes in pulse rate, intoxication, and confusion were also of longer duration for subjects with a past history of intermittent marijuana smoking. The influence of past history of marijuana use on marijuana-induced alterations in pulse rate, intoxication, and mood for females appears to be similar to males. These similarities are not attenuated as a function of the menstrual-cycle phase of females.

A new tool for studying the molecular architecture of the fungal cell wall: one-step purification of recombinant trichoderma beta-(1-6)-glucanase expressed in Pichia pastoris

The fungal cell wall is a supramolecular network of glycoproteins and polysaccharides. Its analysis is seriously hampered by the lack of easily available hydrolytic enzymes in a pure form. Here we describe a simple and efficient purification procedure of a recombinant beta-(1-6)-glucanase from Trichoderma harzianum expressed in Pichia pastoris. Transformed cells efficiently secreted the enzyme into the induction medium. We purified the enzyme using a one-step method based on hydrophobic interaction chromatography. The yield was 80%. SDS-PAGE of the purified enzyme revealed a single band with an apparent molecular mass of 43 kDa. The isoelectric point of the enzyme was 5.8, and it showed maximal enzyme activity and stability at pH 5.0. As beta-(1-6)-glucan is an important component of fungal cell walls, the easy availability of pure beta-(1-6)-glucanase will highly facilitate studies of the molecular organization of the fungal cell wall.

Use of antibiotic agents in a large teaching hospital. The impact of Antibiotic Guidelines

Three surveys of antibiotic use have been conducted at The Royal Melbourne Hospital. The first was conducted in 1978, before the introduction of the booklet, Antibiotic Guidelines; the second was conducted eight months after, and the most recent, four years after, its distribution. In 1978, 30% of 563 patients surveyed were receiving antibiotic therapy; this proportion declined to 28% of 967 patients studied in 1982. At the beginning of 1978, 52% of all treatments audited were judged appropriate when compared with those recommended in the Guidelines; this proportion rose to 72% in the second survey and was maintained at 70% in 1982. Certain inappropriate prescribing patterns persisted, such as the use of amoxycillin for the treatment of primary pneumonia, surgical antibiotic prophylaxis which was started too late, and the failure to simplify therapy when the results of microbiological investigations became available. Antibiotic guidelines facilitate the auditing of antibiotic usage and aid rational prescribing. Nevertheless, additional measures appear necessary if specific patterns of misuse of antibiotic agents are to be corrected.

Beta endorphin release in patients after spontaneous and provoked acute myocardial ischaemia

BACKGROUND

In animal models of circulatory shock and heart failure concentrations of the endogenous opioid peptide beta endorphin are raised and opioid receptor blockade improves haemodynamic variables and survival. This study was performed to identify whether acute myocardial ischaemia provokes the release of beta endorphin in humans.

METHODS

Observational study in a university cardiology centre. Serial measurements of beta endorphin made by specific radioimmunoassay were correlated with other clinical and neuroendocrine variables that were measured prospectively. Fifty five patients with acute myocardial ischaemia and 26 patients undergoing elective coronary angioplasty of the left anterior descending coronary artery were studied.

RESULTS

beta endorphin concentrations were raised above the upper limit of normal in 31/42 (74%) patients with confirmed myocardial infarction, 3/13 (23%) patients with unstable angina, and 10/24 (42%) patients after coronary angioplasty. There was no evidence of myocardial release of beta endorphin. There were significant positive correlations between beta endorphin and the concentrations of adrenocorticotrophic hormone, cortisol, and arginine vasopressin. In patients with acute myocardial ischaemia there was a significant positive correlation between the peak concentrations of creatine kinase and beta endorphin but no correlation with visual analogue scores of the intensity of chest pain. The highest beta endorphin concentrations were seen in patients whose clinical course was complicated by the development of heart failure.

CONCLUSIONS

beta endorphin release is a component of the neuroendocrine activation associated with myocardial ischaemia/infarction.

Refractory period fluid stimulation of right atria: a method for studying presynaptic receptors in cardiac autonomic transmission

A method is described for measuring the atrial period or beat interval from the surface electrogram in isolated spontaneously contracting guinea pig right atria. Stimulation of parasympathetic and sympathetic nerve endings can be readily obtained by applying electrical field pulses across the atria during the atrial refractory period to prevent arrhythmia. In the presence of atropine, the atria respond to a single field pulse with a slight tachycardia that can be taken as a measure of the released transmitter norepinephrine. Because the effector response is mediated by a beta-adrenoreceptor, this preparation is particularly suited for the study of the pharmacology of presynaptic alpha-adrenoreceptors. The fall in period (tachycardia) to one-, two-, or four-field pulses delivered one per consecutive refractory period is linear, and the responses are reproducible for many hours. This biological system offers advantages in sensitivity and stability over methods employing radiolabeled norepinephrine in the study of presynaptic receptors in cardiac autonomic transmission.