Cardio-Oncology: a medical specialty in constant growth and evolution. the 10-year experience of the first cardio-oncology service in the United Kingdom

Introduction

Survivorship has increased significantly in cancer patients with the advent of novel therapies. However, this improvement has been at the cost of higher rates of cardiotoxicity. Cardiovascular disease has become the main cause of death or cancer therapy interruption in many of these patients. The need for specialist services to deal with these emerging problems has led to global development of many Cardio-Oncology services.

Objectives

To describe how a Cardio-Oncology service has grown and evolved over a 10 year period in response to the constantly changing oncological landscape.

Methods and results

Prospective, single center, study of cancer patients referred to our service from February 2011 to December 2021. 1499 patients were referred to the service. Mean age was 60 years (SD: 15) and 60% were female. CV risk factors including hypertension (32%), dyslipidaemia (12%) and diabetes (6%) were common.

The most frequent primary tumour location was breast (427 patients, 28%), followed by haematological (151, 10%) and gastrointestinal tract (114, 8%). The average number of referrals per month increased 6 fold from 2011, from 3.3 patients per month to 21 patients in 2021. In the last 5 years there was a 10 fold increase in the number of outpatient consultations from 189 consultations in 2016 to 1988 consultations in 2021.

The most frequent reason for referral was pre-treatment assessment (39%), followed by cancer therapy related cardiac dysfunction (CTRCD) (33%) and other acute cancer therapy related CV diseases (CTR-CVDs) (22%). From 2011 to 2017 CTRCD was the main CTR-CVD due to anthracycline and trastuzumab. This ratio changed in 2018 when other CTR-CVDs became the most frequent referral reason following pre-treatment assessment. Patients referred to our service were or had been, mostly under medical therapy alone or in combination with surgery or radiotherapy (1058 patients, 70%), anthracyclines being the predominant treatment (435 patients, 40%). Targeted therapies and immune check point inhibitors became more popular in the last two years (2020–2021). A multivariable logistic regression model was built to assess the relation between the medical treatment and the prevalence of CTRCD vs other CTR-CVDs. Anthracyclines and HER2 therapy are independently associated with a higher prevalence of CTRCD while tyrosine kinase inhibitors and immune checkpoint inhibitors increase the risk of other CTR-CVDs e.g. hypertension, arrhythmias and myocarditis.

Conclusions

Cardio-Oncology has rapidly evolved from its origin as a subspecialty of heart failure medicine, to a diverse medical specialty that encompasses many different domains of cardiology. Future cardio-oncology services should reflect this and be dynamic, collaborating with cardiac sub-specialities as necessary. Provision of cardio-oncology services requires a considerable knowledge and understanding of the ever growing and changing oncology therapies.

Funding Acknowledgement

Type of funding sources: None.

A comparison of HFrEF vs HFpEF's clinical workload and cost in the first year following hospitalization and enrollment in a disease management program

BACKGROUND

Admission with heart failure (HF) is a milestone in the progression of the disease, often resulting in higher intensity medical care and ensuing readmissions. Whilst there is evidence supporting enrolling patients in a heart failure disease management program (HF-DMP), not all reported HF-DMPs have systematically enrolled patients with HF with preserved ejection fraction (HFpEF) and there is a scarcity of literature differentiating costs based on HF-phenotype.

METHODS

1292 consenting, consecutive patients admitted with a primary diagnosis of HF were enrolled in a hospital based HF-DMP and categorized as HFpEF (EF≥45%) or HFrEF (EF<45%). Hospitalizations, primary care, medications, and DMP workload with associated costs were evaluated assessing DMP clinic-visits, telephonic contact, medication changes over 1year using a mixture of casemix and micro-costing techniques.

RESULTS

The total average annual cost per patient was marginally higher in patients with HFrEF €13,011 (12,011, 14,078) than HFpEF, €12,206 (11,009, 13,518). However, emergency non-cardiovascular admission rates and average cost per patient were higher in the HFpEF vs HFrEF group (0.46 vs 0.31 per patient/12months) & €655 (318, 1073) vs €584 (396, 812). In the first 3months of the outpatient HF-DMP the HFrEF population cost more on average €791 (764, 819) vs €693 (660, 728).

CONCLUSION

There are greater short-term (3-month) costs of HFrEF versus HFpEF as part of a HF-DMP following an admission. However, long-term (3-12month) costs of HFpEF are greater because of higher non-cardiovascular rehospitalisations. As HFpEF becomes the dominant form of HF, more work is required in HF-DMPs to address prevention of non-cardiovascular rehospitalisations and to integrate hospital based HF-DMPs into primary healthcare structures.

Surgical management of complex multiloculated hydrocephalus in infants and children

OBJECTIVE

Multiloculated hydrocephalus may occur as a consequence of intraventricular hemorrhage or infection and is characterized by enlargement of multiple noncommunicating intraventricular and/or periventricular cysts. In this study, we report the outcomes of open and endoscopic fenestration for multiloculated hydrocephalus at our institution.

METHODS

Records of children who underwent endoscopic or open fenestration at St. Louis Children's Hospital from 1999 to 2011 were analyzed. The cause of MLH, operative parameters, length of hospital stay, and subsequent shunt intervention rate were recorded.

RESULTS

Twenty-five subjects were identified for study. Twelve subjects underwent open craniotomy and 13 underwent endoscopic fenestration. Endoscopic fenestration was associated with decreased blood loss, operative time, and length of stay (p = 0.003, 0.002, 0.02, respectively). Subjects undergoing craniotomy had an average of 5.1 ± 4.5 subsequent shunt-related interventions versus 3.1 ± 4.0 in the endoscopy group (p = 0.25). The craniotomy group's median subsequent shunt revision rate was 0.74 interventions per year versus 0.50 interventions per year in the endoscopy group (p = 0.51). Fifty percent of subjects in the open fenestration group required additional fenestration surgery compared to 38.5% in the endoscopic group (p = 0.70).

CONCLUSION

Both open and endoscopic fenestration appeared effective at improving shunt management. The endoscopic technique may offer advantages in operative time, blood loss, and length of hospital stay. These data suggest that endoscopic fenestration may be used as the initial approach for treatment of multiloculated hydrocephalus, with craniotomy and open fenestration used for more severe or refractory cases.

Genetic variation in DNMT3B and increased global DNA methylation is associated with suicide attempts in psychiatric patients

Recently, a significant epigenetic component in the pathology of suicide has been realized. Here we investigate candidate functional SNPs in epigenetic-regulatory genes, DNMT1 and DNMT3B, for association with suicide attempt (SA) among patients with co-existing psychiatric illness. In addition, global DNA methylation levels [5-methyl cytosine (5-mC%)] between SA and psychiatric controls were quantified using the Methylflash Methylated DNA Quantification Kit. DNA was obtained from blood of 79 suicide attempters and 80 non-attempters, assessed for DSM-IV Axis I disorders. Functional SNPs were selected for each gene (DNMT1; n = 7, DNMT3B; n = 10), and genotyped. A SNP (rs2424932) residing in the 3' UTR of the DNMT3B gene was associated with SA compared with a non-attempter control group (P = 0.001; Chi-squared test, Bonferroni adjusted P value = 0.02). Moreover, haplotype analysis identified a DNMT3B haplotype which differed between cases and controls, however this association did not hold after Bonferroni correction (P = 0.01, Bonferroni adjusted P value = 0.56). Global methylation analysis showed that psychiatric patients with a history of SA had significantly higher levels of global DNA methylation compared with controls (P = 0.018, Student's t-test). In conclusion, this is the first report investigating polymorphisms in DNMT genes and global DNA methylation quantification in SA risk. Preliminary findings suggest that allelic variability in DNMT3B may be relevant to the underlying diathesis for suicidal acts and our findings support the hypothesis that aberrant DNA methylation profiles may contribute to the biology of suicidal acts. Thus, analysis of global DNA hypermethylation in blood may represent a biomarker for increased SA risk in psychiatric patients.

Control of cryptosporidiosis in neonatal calves: use of halofuginone lactate in two different calf rearing systems

To date there is no effective treatment for bovine cryptosporidiosis. This study describes the use of halofuginone lactate in preventing cryptosporidiosis in naturally infected neonatal calves on a dairy farm with a high prevalence of infection. The animals were kept in two different calf rearing systems. A randomized double-blind trial was carried out with 32 naturally infected calves, divided into four groups. The two prophylactic halofuginone lactate treated groups were kept in either individual or group pens. Similarly, the animals receiving the placebo were housed in either individual pens or together in a large pen. A total of ten faecal samples were collected periodically during the 28 days study from each calf and tested for the presence of Cryptosporidium spp. using microscopic and molecular methods. Generalized estimating equations models were used to determine if the effects of the various treatments and/or rearing systems on the presence of diarrhoea and infection were statistically significant. Further analysis (classification trees models) was carried out to explore possible risk factors for cryptosporidiosis and interactions between treatments and rearing systems. Halofuginone lactate was shown to be effective in reducing clinical signs of cryptosporidiosis and environmental contamination. However, the treatment did not delay the onset of diarrhoea and did not reduce the risk of infection amongst calves reared together in a highly contaminated environment. The use of halofuginone lactate in combination with good hygienic measures, such as rearing animals in clean individual pens, was the most effective method to reduce the risk of cryptosporidiosis amongst 7-13 days old calves. It was concluded that the control of the parasite could be achieved by the combination of using effective preventive drugs, such as halofuginone lactate and good animal husbandry procedures.

Spatial distribution of risk factors for Cryptosporidium spp. transport in an Irish catchment

Cryptosporidium spp. has become a major public health concern in many parts of the globe, including Ireland, as a result of recent reported waterborne outbreaks of Cryptosporidiosis. Continuous monitoring of Cryptosporidium spp. in water supplies is not feasible, so a risk-forecasting approach is required. This study reports a globally applicable approach for evaluating the spatial variation in relative risk of contaminating surface water by Cryptosporidium spp. based on a risk potential index (RPI) as an indicator of the potential pollution of surface water. The RPI is predicted by readily available data on land use, rainfall, soil type, slope, soil moisture deficit, and distance from water course. A small catchment in County Meath, Ireland, was chosen to illustrate the analysis of the approach. Data for the study area were digitized and rectified using surveyed ground control points to capture each of the RPI factors, field boundaries, and land use. The six parameters were classified and assigned a relative risk score out of 5. A Geographic Information Systems overlay analysis then was used to calculate a cumulative relative risk score for each month of the year. The analysis indicated that April and June experienced a relatively low risk of Cryptosporidium spp. transport compared with other months of the year. June had the least risk, because more than 98% of the catchment was estimated to be of low or moderate risk (RPI ranges = 0 to 2). December had the highest risk of Cryptosporidium spp. transport, because approximately 20% of the catchment area had a moderately high to very high risk (RPI ranges = 2 to 5). The study also made an attempt to reduce the risk of contaminating surface water by alternative land-use practice and relocating the field boundaries. The study demonstrated a semi-quantitative and readily implemented method for using spatial risk assessment for planning land management to reduce the risk of surface water contamination by Cryptosporidium spp. from agricultural sources. The approach could be used in any catchment with similar hydrological characteristics subject to a surface water pathogen contamination risk from grazing livestock.

Anisakid larvae in Atlantic salmon (Salmo salar L.) grilse and post-smolts: molecular identification and histopathology

The molecular identification and histopathology are described for the parasitic larvae of a nematode species present in the abdominal cavity of Atlantic salmon ( Salmo salar ) grilse caught in fish traps on their natal river in the west of Ireland and post-smolts collected during experimental trawls on the continental shelf edge of the northeast Atlantic Ocean. Larvae in the adult and juvenile salmon were identified as Anisakis simplex sensu stricto by PCR amplification and RFLP and sequencing of the ITS gene and PCR amplification and sequencing of the cox2 gene. Parasitic nematode larvae in the grilse were either encapsulated in the abdominal mesentery associated with the pyloric ceca or on the serosal surface of the liver and in the vent region. In some fish, larvae were found in the parenchyma of the liver and muscularis circularis of the intestine. In general, the larvae induced a limited cellular response apart from the occurrence of focal melanin macrophage aggregates and individual eosinophilic granular cells in the connective tissue capsule. Melanin macrophage aggregates were also present among the hepatocytes adjacent to encapsulated larvae in the liver. The reaction to the parasites was more severe in the wall of the intestine. Encapsulated nematode larvae caused displacement, vacuolation, and necrosis of the circular muscle fibers. The stratum compactum was also disrupted with focal areas of degeneration. Overall, the intestinal wall had a hypercellular appearance with extensive cellular infiltration comprising eosinophilic granular cells, macrophages, lymphocytes, and fibrocytes. The post-smolts were caught in May during the early oceanic phase of their life cycle. In these fish, A. simplex sensu stricto larvae were found lying free on the serosal surface of the intestine and liver without any apparent histologic changes. This is the earliest in the marine migration of Atlantic salmon that A. simplex sensu stricto infection has been recorded.

The emergence of DNA methylation as a key modulator of aberrant cell death in prostate cancer

It is now well established that cancer cells exhibit a number of genetic defects in the machinery that governs programmed cell death and that sabotage of apoptosis is one of the principal factors aiding in the evolution of the carcinogenic phenotype. A number of studies have implicated aberrant DNA methylation as a key survival mechanism in cancer, whereby promoter hypermethylation silences genes essential for many processes including apoptosis. To date, studies on the methylation profile of apoptotic genes have largely focused on cancers of the breast, colon and stomach, with only limited data available on prostate cancer. Here we discuss the major developments in the field of DNA methylation and its role in the regulation of aberrant apoptosis in prostate cancer. The most significant advances have involved the discovery of apoptotic gene targets of methylation, including XAF1, (fragile histidine triad (FHIT ), cellular retinol binding protein 1 (CRBP1), decoy receptor 1(DCR1), decoy receptor 2 (DCR2 ), target of methylation-induced silenceing 1 (TMS1), TNF receptor superfamily, member 6 (FAS), Reprimo (RPRM) and GLI pathogenesis-related 1 (GLIPR1). These genes are reported to be hypermethylated in prostate cancer and some offer potential as diagnostic and prognostic markers. We also introduce the concept of an 'apoptotic methylation signature' for prostate cancer and evaluate its potential in a diagnostic, prognostic and therapeutic setting.

Study on the prevalence of Toxoplasma gondii and Neospora caninum and molecular evidence of Encephalitozoon cuniculi and Encephalitozoon (Septata) intestinalis infections in red foxes (Vulpes vulpes) in rural Ireland

Thoracic fluid (pleural fluid and clotted blood) from 206 foxes were examined for antibodies to Toxoplasma gondii and 220 thoracic fluid samples were tested for Neospora caninum antibodies using indirect immunofluorescent antibody tests (IFAT). A total of 115 (56%) and six (3%) foxes had antibodies to T. gondii and N. caninum, respectively. The brains from 148 foxes were examined for histological lesions and pathological changes suggestive of parasitic encephalitis were observed in 33 (22%). Two thirds of these foxes had antibodies to T. gondii and one fox had antibodies to both T. gondii and N. caninum. PCR assays carried out on DNA extracted from the 33 brains with histological lesions were negative for N. caninum but one of the brains was positive for T. gondii. Microsporidian DNA was also amplified from the brains of two of these foxes. Sequencing these amplicons revealed 100% homology with Encephalitozoon (Septata) intestinalis in one fox and Encephalitozoon cuniculi in the second fox. This is the first report of Encephalitozoon infections in wildlife in Ireland.

A study of helminth parasites in culled cows from Ireland

The objective of this study was to determine the prevalence and intensity of gastrointestinal nematode, lungworm and liver fluke infection in culled cows in Ireland. Abomasa, colorectal contents and livers were collected from 30 to 68 culled beef and dairy cows during autumn 2002 and summer 2003, respectively. Ostertagia ostertagi were found in the abomasa of only three (10%) cows sampled in autumn and in 38 (57%) cows examined in summer. The majority of positive animals had low burdens of O. ostertagi but a few individuals in the group sampled during the summer had a moderate infection (5000-10,000 adult worms). A proportion of the cows in the summer group were also co-infected with small numbers of Trichostrongylus axei. Cooperia oncophora predominated in the recoveries from the larval cultures although O. ostertagi were also recovered. The overall prevalence of Dictyocaulus viviparus was 14%, based on larval identification in faecal samples. Liver fluke, or varying degrees of pathology attributable to Fasciola hepatica, were present in 65% of the livers. The results of this study extend those of previous workers, which were largely limited to dairy cows alone and which focussed on gastrointestinal nematodes and did not include simultaneous infections with lungworm and liver fluke. It was concluded, from the level of polyparasitism evident in this study, that adult cattle should be considered in preventative approaches to bovine helminthosis.

Maturational changes in airway smooth muscle shortening and relaxation. Implications for asthma

Greater airway responsiveness in healthy juveniles is considered a factor in the higher asthma prevalence at a young age compared with adults. Several studies on the contractile response of airway smooth muscle (ASM) from birth to adulthood have addressed the hypothesis that a maturation of ASM plays a role in juvenile airway hyperresponsiveness. Maturation of distinct ASM properties, i.e. force generation, shortening, and relaxation, has been reported, although the majority of the studies have focused on maturation of maximum force and/or sensitivity to contractile agonists. However, in most animal species maturation of the ability to generate force does not correlate with maturation of airway responsiveness. Ontogenesis of ASM shortening has been less extensively studied and the existing reports emphasize an increase during maturation of tissue passive forces opposing shortening. ASM spontaneous relaxation has been very minimally investigated. We have recently demonstrated that the ability of ASM to spontaneously relax during stimulation is sharply reduced in juvenile airway tissue. It remains to be determined the role of these ASM properties in the onset of childhood asthma and whether specific alterations are induced by the occurrence of obstructive airway diseases in young individuals.

Multiple forms of formamidopyrimidine-DNA glycosylase produced by alternative splicing in Arabidopsis thaliana

Formamidopyrimidine-DNA glycosylase (FPG) catalyzes the initial steps in the repair of DNA containing oxidized purines. Two cDNA clones from Arabidopsis thaliana encoding homologs of bacterial FPG have previously been described. We now report that there are at least five additional variants of FPG mRNA in Arabidopsis, each apparently produced from the same gene (AtMMH) by alternative splicing. Thus, AtMMH, like at least four other genes in the base excision repair pathway of human cells, produces multiple forms of protein product through alternative splicing. The variant forms of Arabidopsis FPG may be localized in different locations in the cells, may have different preferences for oxidized substrates, and/or may recruit different proteins that guide the subsequent steps of base excision repair.

Epidemiological studies of human and animal Salmonella typhimurium DT104 and DT104b isolates in Ireland

A total of 122 human and animal Salmonella Typhimurium DT104 isolates and 6 epidemiologically related DT104b isolates from human and animal products were analysed by pulsed-field gel electrophoresis (PFGE). Genomic DNA was subjected to macrorestriction with three enzymes, SpeI, SfiI and XbaI. A total of 14 restriction fragment length polymorphism (RFLP) profiles were identified when the PFGE patterns from the three enzymes were combined. The majority of isolates (81.2%) exhibited the same RFLP profile. Six animal DT104 isolates, susceptible to enrofloxacin and resistant to naladixic acid, were identified from the antibiotic susceptibility test. Four of these isolates had a different PFGE profile from the common RFLP. In addition, 4 of the 6 isolates were geographically clustered in one region. It was concluded that there was one predominant strain of S. Typhimurium DT104 in Ireland and that the potential and selection pressures for emergence of fluoroquinolone-resistant isolates were present.

Alternative forms of formamidopyrimidine-DNA glycosylase from Arabidopsis thaliana

Formamidopyrimidine-DNA glycosylase (FPG) catalyzes the initial steps in the repair of DNA containing oxidized purines. Two complementary DNA clones encoding homologs of bacterial FPG, designated Atfpg-1 and Atfpg-2, have been isolated from Arabidopsis thaliana. They are products of alternative splicing of the transcript of a single gene. Proteins encoded by both clones, AtFPG-1 and AtFPG-2, engineered to contain oligohistidine sequences on their C-terminal ends, were expressed in Escherichia coli and purified, and their activities were assayed. Both proteins cleaved DNA that contained apurinic sites, indicating that they have abasic lyase activity. AtFPG-1, but not AtFPG-2, showed significant cleavage of a double-stranded oligonucleotide that contained 8-oxo-guanine, indicating that the structural differences between the two proteins influence their enzymatic activities. However, both proteins were able to cleave the same sites in DNA that was treated with visible light in the presence of methylene blue.

Therapeutic efficacy of GAR-936, a novel glycylcycline, in a rat model of experimental endocarditis

GAR-936, a novel glycylcycline, was investigated with a rat model of experimental endocarditis. It was compared with vancomycin against both vancomycin-susceptible and -resistant Enterococcus faecalis and methicillin-resistant Staphylococcus aureus. GAR-936 exhibited the lowest MICs (</=0.12 microgram/ml) in vitro against each of the isolates tested. Endocarditis was established by placement of a catheter across the aortic valve, followed by intravenous injection of 10(6) CFU of bacteria 48 h later. Treatment with GAR-936 or vancomycin was initiated 24 to 36 h after bacterial infection and administered subcutaneously twice a day for 3 days at ascending doses. GAR-936 reduced bacterial vegetation titers by >2 log(10) CFU, compared to those in untreated controls, for both vancomycin-susceptible and -resistant (VanA and VanB) E. faecalis strains and >4 log(10) CFU for a methicillin-resistant S. aureus isolate. The glycylcycline was more efficacious at a lower administered dose in the rat model of endocarditis than was vancomycin. The efficacy of GAR-936 in this model was apparently not enhanced by a factor in rat serum, as was observed for vancomycin with a time-kill curve. The results of this study demonstrate the therapeutic potential of GAR-936 for the treatment of enterococcal and staphylococcal infections and warrant further investigation.

Different ontogeny of rate of force generation and shortening velocity in guinea pig trachealis

Juveniles of many species, including humans, display greater airway responsiveness than do adults. This may involve changes in airway smooth muscle function. In the present work we studied force production and shortening velocity in trachealis from 1-wk-old (1 wk), 3-wk-old (3 wk), and 3-mo-old (adult) guinea pigs. Strips were electrically stimulated (60 Hz, 18 V) at their optimal length (l(o)) to obtain maximum active stress (P(o)) and rate of stress generation. Then, force-velocity curves were elicited at 2.5 s from the onset of the stimulus. By applying a recently developed modification of Hill's equation for airway smooth muscle, the maximum shortening velocity at zero load (V(o)) and the value alpha. gamma/beta, an index of internal resistance to shortening (Rsi), were calculated (alpha, beta, and gamma are the constants of the equation). P(o) increased little with maturation, whereas the rate of stress generation increased significantly (0.40 +/- 0.03, 0.45 +/- 0.03, 0. 51 +/- 0.03 P(o)/s for 1 wk, 3 wk, and adult animals). V(o) slightly increased early with maturation to decrease significantly later (1. 79 +/- 0.67, 2.45 +/- 0.92, and 0.55 +/- 0.09 l(o)/s for 1 wk, 3 wk, and adult animals), whereas the Rsi showed an opposite trend (14.98 +/- 5.19, 8.99 +/- 3.01, and 32.07 +/- 5.54 mN. mm(-2). l(o)(-1). s for 1 wk, 3 wk, and adult animals). This early increase of force generation in combination with late increase of Rsi may explain the changes of V(o) with age. An elevated V(o) may contribute to the incidence of airway hyperresponsiveness in healthy juveniles.

The lung in sickle cell disease

Sickle cell disease is the most common inherited disorder in African-Americans. Although the primary defect is hematological, the changes in the erythrocytes lead to a vasculopathy with multiorgan injury. The pulmonary complications, i.e., acute chest syndrome and chronic sickle cell lung disease, are significant causes of morbidity and mortality. The pulmonary manifestations result from a unique constellation of factors which come into play in sickle cell disease. Based on the growing understanding of the molecular and cellular biology of sickle cell disease, new therapies are being developed that are likely to ameliorate the natural history of this disease and its complications.

Requirement for reactive oxygen species in serum-induced and platelet-derived growth factor-induced growth of airway smooth muscle

Reactive oxygen species have been recently identified as important mediators of mitogenic signaling in a number of cell types. We therefore explored their role in mediating mitogenesis of airway smooth muscle. The antioxidants catalase, N-acetylcysteine, and probucol significantly reduced proliferation in primary cultures of rat tracheal smooth muscle stimulated with fetal bovine serum or platelet-derived growth factor, without affecting cell viability or inducing apoptosis. N-Acetylcysteine also significantly reduced serum-stimulated elevation of c-Fos but did not prevent the normal mitogen-induced increase in c-fos mRNA. Fractionation of ribosomes by sucrose density centrifugation and subsequent dot-blot Northern analysis revealed that antioxidants reduced incorporation of c-fos mRNA into the heaviest polyribosomes, suggesting redox regulation of c-fos mRNA translation. Serum treatment of monolayers produced a small but reproducibly significant rise in superoxide dismutase-inhibitable reduction of ferricytochrome c by myocyte monolayers. Serum-induced ferricytochrome c reduction, cellular proliferation, and c-Fos elevation were decreased by the flavoprotein-dependent enzyme inhibitor dipheyleneiodonium. Growth responses to fetal bovine serum and superoxide dismutase-inhibitable reduction of ferricytochrome c were not different between cultured tracheal myocytes from wild-type versus gp91 phagocyte oxidase null mice. These results suggest that mitogen stimulation of airway smooth muscle induces signal transduction of cell proliferation that is in part dependent on generation of partially reduced oxygen species, generated by an NADH or NADPH oxidoreductase that is different from the oxidase in phagocytic cells.

Symbiotic root nodules of the actinorhizal plant Datisca glomerata express Rubisco activase mRNA

N2-fixing symbiotic root nodules of the actinorhizal host Datisca glomerata express Dgrca (D. glomerata Rubisco activase) mRNA, a transcript usually associated with photosynthetic organs or tissues. In northern blots a mature, 1700-nucleotide Dgrca mRNA was detected in green plant organs (leaves, flowers, and developing fruits) and in nodules but was not detected in roots. A second message of 3000 nucleotides was observed only in nodules. Both size classes of transcripts were polyadenylated. The larger transcript was 2- to 5-fold more abundant than the mature mRNA; it was hybridized to an intronic probe, indicating that a stable, incompletely spliced transcript was accumulating. Treatment with light on excised nodules did not alter the relative abundance of the two species. In in situ hybridizations the Dgrca message was expressed intensely in the nuclei of infected cells. The Dgrca transcripts also accumulated at lower levels in uninfected cortical cells adjacent to the periderm and the vascular cylinder. mRNA encoding the large subunit of Rubisco (DgrbcL) was abundant in mature infected cells and in the amyloplast-rich sheath of uninfected cortical cells lying between the infected cells and nodule periderm. The proteins Rubisco activase, Rubisco, and the 33-kD O2-evolving complex subunit did not accumulate to detectable levels, indicating that a functional photosynthetic apparatus was not prevalent in nodule tissue. Signals or factors required for the transcription of Dgrca appeared to be present in nodules, but efficient splicing and translation of the message were not observed in Frankia-infected tissue where transcript accumulation was highest.

The superoxide synthases of rose cells . Comparison Of assays

In an effort to identify the enzymatic mechanism responsible for the synthesis of reactive oxygen species produced during the hypersensitive response, preparations of rose (Rosa damascena) cell plasma membranes, partially solubilized plasma membrane protein, and cytosol were assayed for the NADH- and NADPH-dependent synthesis of superoxide using assays for the reduction of cytochrome c (Cyt c), assays for the reduction of nitroblue tetrazolium, and assays for the chemiluminescence of N,N'-dimethyl-9,9'-biacridium dinitrate (lucigenin). Each assay ascribed the highest activity to a different preparation: the Cyt c assay to cytosol, the nitroblue tetrazolium assay to plasma membrane, and the lucigenin assay to the partially solubilized plasma membrane protein (with NADH). This suggests that no two assays measure the same set of enzymes and that none of the assays is suitable for comparisons of superoxide synthesis among different cell fractions. With the plasma membrane preparation, the presence of large amounts of superoxide-dismutase-insensitive Cyt c reductase confounded attempts to use Cyt c to measure superoxide synthesis. With the partially solubilized membrane protein, direct reduction of lucigenin probably contributed to the chemiluminescence. Superoxide synthesis detected with lucigenin should be confirmed by superoxide-dismutase-sensitive Cyt c reduction.

Dehydroepiandrosterone and analogs inhibit DNA binding of AP-1 and airway smooth muscle proliferation

The adrenal steroid dehydroepiandrosterone (DHEA) and its analogs reduce growth of immortalized and malignant cell lines. We therefore explored their effects on the growth of airway smooth muscle, whose hyperplasia may lead to fixed airways obstruction and enhanced airways hyperresponsiveness in severe chronic asthma. DHEA and its potent analog 16 alpha-bromoepiandrosterone dramatically reduced proliferation in primary cultures of rat tracheal smooth muscle stimulated with fetal bovine serum or platelet-derived growth factor. Growth inhibition was dose-dependent and could not be attributed to interference with glucose-6-phosphate dehydrogenase activity or cholesterol metabolism, as reported for immortalized or malignant cell lines, respectively. Expression of the early response gene c-fos remained intact, but DHEA and 16 alpha-bromoepiandrosterone decreased DNA binding of the transcription factor activator protein-1, a later response important for expression of genes that mediate DNA synthesis and cell cycle progression. These results suggest that the nonglucocorticoid steroid DHEA and its analogs may impair activation of secondary growth response genes in a fashion analogous to that reported for glucocorticoids and that they may prove useful for treatment of asthmatic airway remodeling in the human.

Comparative biochemistry of the oxidative burst produced by rose and french bean cells reveals two distinct mechanisms

Cultured cells of rose (Rosa damascena) treated with an elicitor derived from Phytophthora spp. and suspension-cultured cells of French bean (Phaseolus vulgaris) treated with an elicitor derived from the cell walls of Colletotrichum lindemuthianum both produced H2O2. It has been hypothesized that in rose cells H2O2 is produced by a plasma membrane NAD(P)H oxidase (superoxide synthase), whereas in bean cells H2O2 is derived directly from cell wall peroxidases following extracellular alkalinization and the appearance of a reductant. In the rose/Phytophthora spp. system treated with N, N-diethyldithiocarbamate, superoxide was detected by a N, N'-dimethyl-9,9'-biacridium dinitrate-dependent chemiluminescence; in contrast, in the bean/C. lindemuthianum system, no superoxide was detected, with or without N,N-diethyldithiocarbamate. When rose cells were washed free of medium (containing cell wall peroxidase) and then treated with Phytophthora spp. elicitor, they accumulated a higher maximum concentration of H2O2 than when treated without the washing procedure. In contrast, a washing treatment reduced the H2O2 accumulated by French bean cells treated with C. lindemuthianum elicitor. Rose cells produced reductant capable of stimulating horseradish (Armoracia lapathifolia) peroxidase to form H2O2 but did not have a peroxidase capable of forming H2O2 in the presence of reductant. Rose and French bean cells thus appear to be responding by different mechanisms to generate the oxidative burst.

Development of a preferential relationship with the mother by the newborn lamb: importance of the sucking activity

Lambs develop a preferential relationship with their mothers within 24 h after birth. In a first experiment, we attempted to determine whether neonatal sucking was a potent reinforcer in the establishment of this preference by temporarily covering the udders of ewes after parturition. Lambs were assigned to one of three treatments: they had free access to the udder (group 1) or were prevented from sucking either between birth and 6 h afterward (group 2) or between 12 and 18 h after birth (group 3). Measurements of cholecystokinin plasma levels at birth and at 6 and 18 h showed that all lambs ingested some colostrum when the udder was made accessible. When tested in a two-choice test situation at 24 h of age, lambs from group 1 spent significantly more time near their mothers than near the alien ewes, those from group 2 did not show any discrimination, and lambs from group 3 clearly preferred the alien ewes. At 2 days of age, lambs from groups 1 and 3 showed a strong preference for their mothers, whereas those from group 2 still displayed no preference. In a second experiment, we attempted to determine whether sucking also had a reinforcing value in the maintenance of this preference. Lambs were assigned to one of three treatments: they had free access to the udder (group 1) or were prevented from sucking for 6 h either at birth (group 2) or at the age of 3 days (group 3). Lambs from group 2 did not discriminate between their own and alien dams when tested at 24 h of age, unlike those of groups 1 and 3. When a second test was performed at 4 days of age, all the lambs showed a strong preference for their dams. We concluded that sucking has strong rewarding properties in the establishment of a preferential relationship with the mother by the lamb. On the other hand, the maintenance of this preference does not rely on sucking as strongly.

Ferricyanide reductase of rose plasma membranes is regulated by nitrogen supply

The ability of suspension-cultured rose (Rosa damascena Mill. cv Gloire de Guilan) cells to reduce ferricyanide is decreased by 50% during an overnight incubation in a low-nutrient (1 mM CaCl2, 0.1 mM KCl) solution. This loss is not observed when nitrate and/or glutamate is added to the low-nutrient medium, but it occurs in medium containing all the components needed for normal growth except nitrate plus glutamate. Thus, the cells possess both constitutive and inducible enzymes for the reduction of ferricyanide, and nitrate or glutamate is both necessary and sufficient to stimulate the production of the inducible enzyme.

Chronic opioids for chronic low back pain--solution or problem?

The article by Brown et al does not provide data to justify long-term opioid use but does suggest a treatment option for the many patients who have chronic back pain and who want the help that our medical delivery system often does not provide. Having worked in a tertiary referral pain clinic that serves many low back pain patients who have demonstrated the ineffectiveness of chronic opiate therapy, I am strongly ambivalent about recommending prescribing ongoing opioiod therapy for chronic pain patients. The caveats about prescribing opioids for such patients are most appropriate (i.e., do not prescribe opioids for those who have a history of problems with opioid therapy or for whom increased intake is associated with decreased function); however, for patients who do not display these problems (and there could be many out there), I am sympathetic with the sentiments expressed by Brown et al. A trial of these drugs might be warranted if all else fails and continued therapy with opioids seems justified, but only with zealous attention to monitoring function and therapeutic compliance, as outlined by the authors. With regard to the doses needed for control, the method of opioid administration might be important, that is, whether it is in tablets or in a masking vehicle. In this day of open dialogue, it is not fashionable to blind the patient to the drug or dose, but I believe blinding has a place in the care of a particular group of patients whose symptom (pain) can vary considerably with time. I have found that most chronic pain patients rarely, if ever, reduce their analgesic intake in better times, but an attentive physician can if masking vehicles are used. Thus the physician can limit the amount of drug consumed long term. In my personal experiences with comparable chronic nonmalignant pain patients (albeit in different hemispheres), the average opioid maintenance (methadone) dosage was halved by prescribing the drug in a masking vehicle rather than as a tablet. If pain complaints are reduced and if function is improved according to the record (eg, patient is working) and the relatives' report, and if you, the prescribing physician, are happy, then a long-term regimen of opioid therapy is probably fine. Further controlled trials are needed to see whether this therapy works, and if so, what are the optimal agent(s) and dosages, what is optimal monitoring, and most important of all, who is the optimal patient who might derive not only analgesia but also functional benefit rather than compromise from this therapy. If we cannot make patients better, we must not make them worse.

Ontogeny of dry gas hyperpnea-induced bronchoconstriction in guinea pigs

Adolescent guinea pigs (AGPs) demonstrate dry gas hyperpnea-induced bronchoconstriction (HIB) that shares key features with HIB in humans with asthma. The airways of immature animals exhibit enhanced reactivity to diverse types of stimulation. We tested whether dry gas HIB is also increased in newborn guinea pigs (NGPs). We quantified HIB as the fractional increase of respiratory system resistance (Rrs) over baseline (BL) in five 4- to 7-day-old NGPs after 10 min of hyperpnea, as well as changes in Rrs elicited by intravenous methacholine or capsaicin, and compared these responses with those of AGPs. During hyperpnea, analogous stimuli were delivered by mechanically imposing hyperpnea at 3.0, 4.5, and 6.0 times quiet eucapnic minute ventilation (VE). In AGPs, hyperpnea caused significant bronchoconstriction that increased with VE; peak fractional increase of Rrs was 7.6 +/- 2.0 times BL. In contrast, hyperpnea caused insignificant bronchoconstriction in NGPs (1.4 +/- 0.2 times BL after the largest VE; P < 0.05 vs. AGP). Responses elicited by methacholine (10(-10)-10(-7) mol/kg) or capsaicin (0.01-10.0 microgram/kg) were similar in NGPs and AGPs. In AGPs, hyperpnea suppressed HIB until posthyperpnea. To determine whether the reduced HIB of NGPs was caused by enhanced suppression, NGPs and AGPs were administered acetylcholine (10(-10)-10(-7) mol/kg i.v.) during BL eucapnic ventilation and during eucapnic hyperpnea with warm humidified gas. Responses to acetylcholine were suppressed in AGPs and NGPs to a similar degree. We conclude that HIB is markedly diminished shortly after birth in guinea pigs and that it increases substantially during maturation.(ABSTRACT TRUNCATED AT 250 WORDS)

Physiological mechanisms mediating enhanced force generation during development and immune sensitization

We examined the development of acetylcholinesterase (AChase) activity and tracheal smooth muscle (TSM) contraction elicited by acetylcholine (ACh) in a swine model of maturation and a dog model of allergic bronchospasm. Strips of TSM were tethered isometrically at optimal length and responses were expressed as a percentage of the maximum to KCl-substituted perfusate (% KCl). Maximal contraction (ATmax) to ACh in 2-week-old swine (168 +/- 8% KCl) was greater than in 10-week-old swine (142 +/- 2% KCl; p less than 0.02). The AChase inhibitor, physostigmine, augmented ACh-elicited ATmax in 10-week-old (27% increase; p less than 0.01) but not in 2-week-old swine (2% increase; p is NS) and caused a greater increase in sensitivity to muscarinic activation in 2 versus 10 week-old swine (p less than 0.02), thus demonstrating increased contraction of TSM in 2 versus 10-week-old swine, which results at least in part from reduced AChase activity in immature animals. In another study, TSM from ragweed-sensitized dogs demonstrated augmented efficacy to ACh-elicited contraction (180 +/- 6% KCl) compared with TSM from sham-sensitized, littermate controls (163 +/- 4% KCl; p less than 0.05). In the presence of physostigmine, ATmax was not different between ragweed-sensitized and control TSM.(ABSTRACT TRUNCATED AT 250 WORDS)

Ontogeny of shortening velocity in porcine trachealis

We examined the effect of maturation on force-velocity (F-V) parameters in porcine tracheal smooth muscle (TSM) to determine the relationship between maximal isometric contractile force (Po) and maximal velocity of shortening (Vmax). Strips of TSM excised from 1-day-old neonatal swine (neo; n = 8), 2-wk-old swine (2ws; n = 7), and 10-wk-old swine (10ws; n = 7) were tethered to an electromagnetic lever system for F-V analysis of contractility. TSM strips were activated by electrical field stimulation at optimal resting tension, voltage, and length (Lo) so that maximal reproducible contractile force (Po) was elicited. Velocities were measured at the early phase of isometric contraction (3.1 +/- 0.1 s for neo, 2.9 +/- 0.1 s for 2ws, and 3.1 +/- 0.1 s for 10ws; P = NS). Shortening velocity increased progressively with maturation; Vmax was 0.164 +/- 0.011 Lo/s for neo, 0.194 +/- 0.013 Lo/s for 2ws (P less than 0.05 vs. neo), and 0.260 +/- 0.024 Lo/s for 10ws (P less than 0.01 vs. neo; P less than 0.05 vs. 2ws). Maximal isometric force generation increased substantially during the first 2 wk of postnatal life and thereafter returned to neonatal levels; Po was 71.5 +/- 2.1 mN/mm2 for neo, 95.4 +/- 7.0 mN/mm2 for 2ws, and 74.7 +/- 6.2 mN/mm2 for 10ws (P less than 0.05, 2ws vs. neo and 10ws). In separate studies, we also determined whether differences in Vmax occurred during the normal cycling phase of the cross bridge (3 s) or during the slowly cycling phase of the latch bridge (8 s) in tissue from 12 additional animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Ontogenic expression of acetylcholinesterase activity in trachealis of young swine

Previous investigations have demonstrated that cholinergic contraction of porcine tracheal smooth muscle (TSM) decreases between the second and tenth weeks of life. In this investigation, we hypothesized that the greater contractile response to acetylcholine (ACh) in TSM of 2-wk-old swine (2ws) vs. 10-wk-old swine (10ws) was the result of a relative decrease in activity of acetylcholinesterase (AChase). To examine this hypothesis, we assessed AChase activity directly in homogenates of TSM from eight 2ws and seven 10ws using a newly adapted method that measures the rate of cleavage of acetylthiocholine; enzyme activity was expressed as absorbance units per minute per milligram protein. The AChase from tissues of both age groups saturated at approximately 3 mM substrate. However, maximal AChase activity (Vmax) was significantly greater in 10ws than 2ws. Eadie-Hofstee analysis of enzyme kinetics revealed similar Michaelis-Menten constants for 2ws and 10ws. The concentration of physostigmine (PS), an inhibitor of cholinesterase, that elicited half-maximal inhibition of AChase activity also was similar for 2ws and 10ws. In separate studies, contraction of TSM strips was assessed in vitro at optimal resting length and expressed as a function of maximal force generation to potassium chloride. Strips of TSM from 2ws contracted with greater force than those of 10ws. After pretreatment with 10(-8) M PS, contractile forces were similar in 2ws and 10ws. We conclude that AChase activity measured directly in muscle homogenates is significantly reduced in TSM of 2ws vs. 10ws and that this may result in augmented contraction to ACh under conditions of zero-order kinetics.

Extracellular Ca2+ mobilization in potential-dependent contraction of trachealis of maturing swine

We studied the effect of maturation on potassium-induced parasympathetic activation and Ca2+ entry in tracheal smooth muscle (TSM) from fifteen 2-wk-old (2ws) and sixteen 10-wk-old (10ws) male domestic farm swine. Atropine (10(-7) M) caused inhibition of the maximal contraction elicited by potassium to 50.3 +/- 2.6% maximum of control response (P less than 0.001) in TSM from 2ws but had no significant effect in TSM from 10ws (94.6 +/- 4.2% maximum; P = NS vs. control). Verapamil (10(-7) M) plus 10(-7) M atropine reduced contraction elicited by potassium in both 2ws (23.7 +/- 5.8% maximum; P less than 0.001 vs. control) and 10ws (50.6 +/- 6.3% maximum; P less than 0.001 vs. control, P less than 0.05 vs. 2ws); 10(-6)M verapamil caused greater than 95% blockade of contraction caused by potassium in both 2ws and 10ws. In separate studies, atropine-treated strips were equilibrated with extracellular Ca2+ concentrations ([Ca2+]o) ranging from normal (1X [Ca2+]o) to four times normal (4x [Ca2+]o). Increasing [Ca2+]o increased maximal contractile response in atropine-treated TSM strips from 68.7 +/- 3.8% maximum for 1x [Ca2+]o to 100.8 +/- 4.8% maximum for 4x [Ca2+]o (P less than 0.001) in 2ws. Neither atropine nor [Ca2+]o affected maximal responses of TSM in 10ws (103.5 +/- 3.0% maximum for 1x [Ca2+]o; P = NS vs. control). However, in the presence of atropine and verapamil, 4x [Ca2+]o augmented KCl-elicited contraction of TSM from both 2ws (46.9 +/- 6.3% maximum; P less than 0.01 vs. control) and 10ws (78.6 +/- 2.3% maximum; P less than 0.005 vs. control).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of maturational changes in myosin content and morphometry on airway smooth muscle contraction

We studied the relationship of airway morphometry, the content of myosin heavy-chain and isoform stoichiometry, and the distribution of bronchoconstrictor responses in the airways of maturing swine. Lungs were excised in 2-wk-old farm swine (2ws; n = 13) and 10-wk-old swine (10ws; n = 13), and tracheal smooth muscle strips and bronchial rings from generations 2-5 were fixed for in vitro isometric measurement of force generation. Split samples were placed in formaldehyde solution or glutaraldehyde for light- or electron-microscopic morphometry or frozen for analysis of tissue myosin content. The rank order of force generation elicited by both receptor- and nonreceptor-dependent mechanisms for both 2ws and 10ws was generation 4 greater than 3 greater than or equal to 2. For all matched airway generations, contractile force was 25-100% greater in 2ws than 10ws. Differences in force generation were not related to morphometric differences in smooth muscle mass content among airways. The relative cross-sectional area of smooth muscle derived by computerized morphometry was 5.5-7% for each airway generation and did not change with age. Electron-microscopic morphometry demonstrated comparable myocyte content within muscle bundles for all airways in both age groups. In generation 4 airways, myocyte size in 2ws (27.3 +/- 0.8 nuclei/2,500 microns2) hypertrophied approximately 15% in 10ws (20.4 +/- 0.6 nuclei/2,500 microns2; P less than 0.01). Tissue content of myosin measured by computerized laser densitometry of gel electrophoresis of homogenates was greater in trachea from 2ws than 10ws (135 +/- 10 vs. 90 +/- 4 micrograms/g tissue; P less than 0.01); homology of 200- and 205-kDa isoforms was confirmed by Western blot against polyclonal myosin antibody and Cleveland digest analysis of each band. Differences in contractile forces between generations in 2ws and 10ws were not correlated to functional myosin isoform content. We demonstrate a maturational downregulation of contractile forces in maturing swine. This response is independent of smooth muscle receptor distribution and is not related to morphological changes in airways muscle mass, cellularity, changes in content of nonmyocyte tissues, or tissue content of functional myosin isoform.

Extrahepatic transcription of human C-reactive protein

We synthesized and cloned cDNA from human peripheral blood mononuclear cell (PBMC) transcripts that were hybrid selected by pCRP5, a liver C-reactive protein (CRP)-specific cDNA (Woo, P.,J.R. Korenberg, and A.S. Whitehead. 1985. J.Biol. Chem. 260:13384). Three hybrid-selected cDNA clones, HScDNA1, HScDNA3, and HScDNA8, were isolated and characterized. Nucleotide sequence analysis of the 5' end of the smaller clones, HScDNA1 and HScDNA8, demonstrated that these two PBMC clones are homologous to the 3' and 5' ends, respectively, of pCRP5. Our largest clone, HScDNA3, is larger than pCRP5, extending beyond both the 5' and 3' limits of pCRP5. Therefore, HScDNA3 was coded by human PBMC and not by the hybrid selection vehicle, pCRP5. HScDNA3 lacks the intervening sequence verifying that this clone is DNA made from a PBMC mRNA and not genomic DNA. The complete nucleotide sequence revealed that HScDNA3 is greater than 99% homologous to the CRP gene. These results demonstrate that PBMC express the CRP gene. Based on our previous report, which shows that peripheral blood cells synthesize a peptide recognized by anti-CRP (Kuta, A.E., and L.L. Baum. 1986. J. Exp. Med. 164:321), in conjunction with the data presented here, we conclude that human PBMC can synthesize CRP.

Comparative studies of Babesia spp. from white-tailed and sika deer

Babesia odocoilei from white-tailed deer (Odocoileus virginianus) in Texas (USA) and B. capreoli isolated from sika deer (Cervus nippon) in Ireland were compared morphologically and antigenically. Babesia odocoilei and B. capreoli paired pyriforms resembled each other closely when in sika deer, but B. odocoilei pyriforms in white-tailed deer were slightly different. Babesia odocoilei in white-tailed deer also differed from B. odocoilei and B. capreoli in sika deer in the frequency of its developmental forms. Indirect immunofluorescence antibody test titres showed that there was some antigen cross-reactivity, but not as much as between B. capreoli and the bovine parasite, B. divergens. The Babesia spp. from deer that we studied appear to be distinct but related species. The low infectivity of B. odocoilei for a splenectomised sika deer suggests that sika deer in North America are probably not very susceptible to this parasite in the wild.

Effect of maturation on topographic distribution of bronchoconstrictor responses in large diameter airways of young swine

We studied the effect of maturation on the topographic distribution of airway constriction in Generations 0 (trachea) through 6 in fourteen 2-wk-old swine (2ws) and sixteen 10-wk-old swine (10ws) in vivo and in excised airways from seven 2ws and seven 10ws in vitro. Animals were anesthetized with chloralose-urethane and received beta-adrenergic blockade and vagotomy prior to generation of random-order, dose-response curves with i.v. methacholine (MCh) and histamine (His) or serotonin (5HT) given intravenously. Lung resistance (RL) was measured, and airway diameter was assessed by tantalum bronchograms obtained at functional residual capacity for each dose of agonist. Baseline RL was substantially greater in 2ws (48 to 62 cm H2O/L/s) than in 10ws (9 to 11 cm H2O/L/s; p less than 0.001 for all groups). Intravenous infusion of 10(-6) mol/kg MCh caused a 416 +/- 110% increase in RL in 2 ws and a 314 +/- 32% increase in RL in 10 ws (p = NS); airway diameter (Daw) decreased by 10 +/- 1% (Generation 2) to 27 +/- 4% (Generation 6) in 2ws and from 8 +/- 2 (Generation 2) to 17 +/- 4% in 10ws. Intravenous infusion of 10(-6) mol/kg His caused a 513 +/- 85% increase in RL in 2ws and a 276 +/- 17% increase in RL in 10 ws (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Investigations on the percutaneous absorption of the antidepressant rolipram in vitro and in vivo

In vitro experiments using full-thickness human skin showed that it was feasible to deliver therapeutic amounts of the new antidepressant drug rolipram. Simple transdermal devices were constructed, and the presence of isopropyl myristate (IPM) in a silicone adhesive (Dow Corning X7-2920) enhanced the flux across excised human skin. The steady-state fluxes from adhesive mixtures containing 0, 5, and 10% IPM were 3, 5.2, and 6 micrograms/cm2/hr, respectively. The in vitro experiments were confirmed in a clinical study involving six healthy male volunteers. The formulations tested were an alcoholic solution and adhesive patches containing 5 and 10% IPM. The dose of drug administered was 0.5 mg/cm2 and the device size 25 cm2. Blood samples were withdrawn over a 24-hr period and analyzed using radioimmunoassay. The topical applications were well tolerated, with only mild or no side effects. A lag time of approximately 2 hr was found for the detection of rolipram in the plasma (detection limit, 50 pg/ml). Interindividual variations both for the peak drug levels and throughout the delivery were quite high but this magnitude of variation has been observed in many other transdermal studies. Plasma levels between 1 and 2 ng/ml were found for all formulations and the AUC0-30 hr was significantly higher for the patch containing 5% IPM.

Group practices tie hospital, physician objectives

Group practice arrangements can underlie a hospital's strategy to recruit physicians and ensure steady patient volumes. Because physicians largely control where their patients are treated, many hospitals are considering ways to more closely align practitioners with their programs and services. Models for developing group practices range from asking young physicians to join an established practice to helping merge the practices of a retiring physician and an established practitioner.

Maturation of acetylcholinesterase expression in tracheal smooth muscle contraction

We examined postganglionic development of acetylcholinesterase (AChase) activity and tracheal smooth muscle (TSM) contraction elicited by cholinomimetic activation and electrical field depolarization in vitro. Epithelium-intact tracheal strips excised from 21 2-wk-old swine (2ws) and 19 10-wk-old swine (10ws) were tethered isometrically at optimal resting length, and responses were expressed as percent of the maximum to 63 mM potassium-chloride (%KCl). Cumulative concentration-response curves to KCl were equivalent for TSM from 2 and 10ws. However, maximal contraction to ACh in 2ws (168 +/- 8.4 %KCl) was greater than for 10ws (142 +/- 2.3 %KCl; P less than 0.02). Stimulus-response curves (field electrodes; AC source) demonstrated greater sensitivity for TSM in 10ws (stimulus causing 50% of the maximal response = 3.32 +/- 0.13 V in 2ws vs. 2.25 +/- 0.12 V in 10ws; P less than 0.001), indicating that the greater cholinomimetic responsiveness of 2ws did not result from augmented presynaptic nerve conduction. The AChase inhibitor, physostigmine, caused 1) greater sensitivity of responses elicited by electrical field stimulation in 2ws (P less than 0.05) but not in 10ws (P = NS), 2) augmentation of maximal responses to exogenous ACh in 10ws (27% increase; P less than 0.01) but not 2ws (2% increase; P = NS), and 3) a greater increase in sensitivity to cholinomimetic activation in 2ws compared with 10ws (P less than 0.02). These data demonstrate increased cholinergic contraction of TSM in 2 vs. 10ws that results at least in part from reduced AChase activity in the trachea of immature animals.

Glucocorticoids fail to inhibit arachidonic acid metabolism stimulated by hydrogen peroxide in the alveolar macrophage

We have previously demonstrated that the biologically important oxidant hydrogen peroxide (H2O2) triggers release and metabolism of arachidonic acid (AA) in the alveolar macrophage (AM). In this study, we evaluated the ability of glucocorticoids to inhibit rat AM AA metabolism stimulated by H2O2, as compared to the particulate zymosan. Methylprednisolone and other glucocorticoids failed to significantly inhibit release of AA stimulated by H2O2, while markedly reducing AA release in response to zymosan. Similarly, methylprednisolone only weakly inhibited synthesis of thromboxane (Tx)B2 stimulated by H2O2, while inhibiting zymosan-induced eicosanoid synthesis to a marked degree. On the other hand, the phospholipase inhibitor mepacrine strongly inhibited AA release and TxB2 formation stimulated by both H2O2 and zymosan, indicating that H2O2 induced AA metabolism is indeed susceptible to pharmacologic inhibition. The failure of glucocorticoids to inhibit AA metabolism stimulated by H2O2 in the AM may in part explain their inability to ameliorate oxidant-mediated lung inflammation and injury.

Complex effects of in vitro hyperoxia on alveolar macrophage arachidonic acid metabolism

Metabolites of arachidonic acid (AA) released into bronchoalveolar lavage fluid of animals exposed to hyperoxia have previously been implicated as mediators of pulmonary oxygen toxicity. The alveolar macrophage (AM) represents an important potential source of these eicosanoids. We have therefore investigated the effects of in vitro hyperoxia (95% O2/5% CO2) versus normoxia (95% air/5% CO2) on the metabolism of AA in the AM of the rat. Exposure to 95% O2 for up to 72 h did not impair the viability or affect the protein content of cultured AMs. Hyperoxia for 24 to 72 h increased the accumulation of free AA liberated from endogenous stores in cultures of resting AMs. Despite this increase in free AA, no changes in synthesis of thromboxane B2, prostaglandin (PG) E2, PGF2 alpha, leukotriene (LT) B4, or LTC4 were observed in resting AMs exposed to hyperoxia for up to 72 h. This was not due to degradation of eicosanoids in hyperoxia. However, formation of cyclooxygenase metabolites from exogenously supplied AA was reduced in hyperoxia-incubated AMs, suggesting that hyperoxia inhibited the cyclooxygenase enzyme. In AMs stimulated with calcium ionophore A23187, both AA release and synthesis of cyclooxygenase and lipoxygenase eicosanoids were augmented after incubation in hyperoxia for 24 to 72 h. The increase in A23187-stimulated LTB4 synthesis caused by hyperoxia was inhibited by the antioxidants catalase, superoxide dismutase, and the intracellular cysteine loading agent L-2-oxothiazolidine-4-carboxylic acid, suggesting that the augmentation by hyperoxia of A23187-induced AA metabolism was mediated by reactive oxygen metabolites. Thus, hyperoxia has complex effects on AA metabolism in the AM, which include the ability to augment the release of AA and formation of bioactive eicosanoids. These findings support a possible role for eicosanoid synthesis by the AM in the pathogenesis of oxygen toxicity of the lung.

Expression of airway contractile properties and acetylcholinesterase activity in swine

We studied the effect of maturation on contractile properties of tracheal smooth muscle from seventeen 2-wk-old swine (2ws) and fifteen 10-wk-old swine (10ws) in situ and in vitro. The response to parasympathetic stimulation was studied in situ in isometrically fixed segments. Contraction was elicited at lower frequencies [half-maximal response to electrical stimulation (ES50) = 6.7 +/- 0.05 Hz] in 2ws than in 10ws (ES50 = 9.1 +/- 0.4 Hz; P less than 0.01). Despite substantial differences in morphometrically normalized cross-sectional area in 2ws (0.012 +/- 0.003 cm2) and 10ws (0.028 +/- 0.001 cm2; P less than 0.01), maximal active tension elicited by parasympathetic stimulation was similar (12.4 +/- 3.2 g/cm in 2ws vs. 13.3 +/- 2.3 g/cm in 10ws; P = NS). In separate in vitro studies in 25 tracheal smooth muscle strips from 10 swine, concentration-response curves generated with potassium-substituted Krebs solution (KCl) were similar in 2ws and 10ws. In 58 other strips (10 swine), maximal active force elicited with acetylcholine (ACh) in 2ws was significantly greater than for 10ws (P less than 0.001). Removal of the epithelium had no effect. However, cholinesterase inhibition with 10(-7) M physostigmine augmented the response to ACh in 10ws (P less than 0.02) but not 2ws. We demonstrate increased force generation and sensitivity to vagal stimulation in 2ws vs. 10ws, which corresponds to increased reactivity to ACh in vitro. The relative hyperresponsiveness in 2ws is specific for cholinergic response and is attenuated at least in part by maturation of the activity of acetylcholinesterase enzyme.

Effects of Extracellular pH on UV-Induced K Efflux from Cultured Rose Cells

Ultraviolet (UV) light causes a specific leakage of K(+) from cultured rose cells (Rosa damascena). During K(+) efflux, there is also an increase in extracellular HCO(3) (-) and acidification of the cell interior. We hypothesized that the HCO(3) (-) originated from intracellular hydration of respiratory CO(2) and served as a charge balancing mechanism during K(+) efflux, the K(+) and HCO(3) (-) being cotransported out of the cell through specific channels. An alternative hypothesis which would yield similar results would be the countertransport of K(+) and H(+). To test these hypotheses, we studied the effect of a range of external pH values (pH 5-9), regulated by various methods (pH-stat, 100 millimolar Tris-Mes buffer, or CO(2) partial pressure), on the UV-induced K(+) efflux. Both UV-C (<290 nanometers) and UV-B (290-310 nanometers) induced K(+) efflux with a minimum at about pH 6 to 7, and greater efflux at pH values of 5, 8, and 9. Since pH values of 8 and 9 increased instead of reduced the efflux of K(+), these data are not consistent with the notion that the efflux of K(+) is dependent on an influx of H(+), a process that would be sensitive to external H(+) concentration. We suggest that the effect of pH on K(+) efflux may be mediated through the titration of specific K(+)-transporting proteins or channels in the plasma membrane. Since we could not detect the presence of carbonic anhydrase activity in cell extracts, we could not use the location of this enzyme to aid in our interpretation regarding the site of hydration of CO(2).

Evidence for platelet-activating factor secretion during immune activation in dogs

To elucidate the potential physiological significance of platelet-activating factor (PAF) in acute bronchoconstriction, we studied the effect of Ascaris suum antigen on the tachyphylactic response to PAF in 15 natively allergic mongrel dogs in vivo. Active bronchial tension was measured isometrically, and mediator secretion was measured as the arteriovenous difference (AVd) in plasma concentration across the lungs. Administration of PAF into the bronchial artery caused dose-related contraction in five control dogs (maximal active tension = 11.8 +/- 1.68 g/cm) that paralleled the increase in the AVd for serotonin (4,188 +/- 175 pg/ml) but not histamine (maximal AVd less than 6.0 ng/ml). The response to PAF was highly tachyphylactic. In contrast to PAF, 1:10 concentration of intra-arterial antigen caused substantial release of histamine (AVd = 308 +/- 57.1 ng/ml; P less than 0.001 vs. PAF). Diminished responsiveness (2-log shift in threshold and maximal contraction; P less than 0.001) to PAF was demonstrated in five dogs after 1:10 antigen, compatible with endogenous release of PAF during prior immune challenge in the same animals. Administration of Ascaris antigen caused a leftward shift in the dose-response curve to serotonin and only mild tachyphylaxis to the maximal response to histamine. Our data are compatible with physiological participation of PAF in eliciting bronchial smooth muscle contraction during the acute phase of immune activation caused by A. suum antigen.

Effects of vasomotor- and mediator-induced hypotension on bronchomotor tone in swine

We studied the sympathetic neural response on airways to hypotensive stimuli in 19 swine in vivo. The effects of pharmacologically induced hypotension with nitroprusside (NTP) and hypotension elicited by intravenous compound 48/80 (48/80), a mast cell degranulating agent, were compared after equivalent reductions in mean arterial blood pressure (MAP). Reduction of the MAP to 60% of base line with NTP in six swine caused an increase in plasma epinephrine (E) from 60 +/- 28 to 705 +/- 276 pg/ml (P = 0.032) and plasma norepinephrine (NE) from 270 +/- 46 to 796 +/- 131 pg/ml (P = 0.032). Comparable reduction in MAP elicited with 48/80 in six other swine caused a substantially greater increase in both plasma E (9,581 +/- 4,147 pg/ml; P = 0.012 vs. NTP group) and plasma NE (2,239 +/- 637 pg/ml; P = 0.041 vs. NTP group). Catecholamine secretion attenuated mediator-induced changes in lung resistance (RL). In animals receiving 48/80, RL increased from 2.97 +/- 0.31 to 7.44 +/- 0.56 cmH2O.l-1.s. In animals having ganglionic blockade with 7.5 mg/kg iv hexamethonium and beta-adrenergic blockade with propranolol (4.0 mg/kg iv followed by 40 micrograms/kg-1.min-1), comparable doses of 48/80 caused an increase in RL to 18.6 +/- 4.55 cmH2O.l-1.s (P less than 0.04 vs. swine receiving neither hexamethonium nor propranolol).(ABSTRACT TRUNCATED AT 250 WORDS)

PAF-induced contraction of canine trachea mediated by 5-hydroxytryptamine in vivo

We studied the secretory correlates of tracheal smooth muscle contraction caused by platelet-activating factor (PAF) in nine mongrel dogs in vivo. In five dogs, dose-response curves were generated by rapid intra-arterial injection of 10(-10) to 10(-6) mol PAF into the isolated tracheal circulation; tracheal contractile response was measured isometrically in situ. To examine the mechanism by which PAF elicits contraction of canine trachealis, concentrations of serotonin (5-HT) and histamine were assayed in the venous effluent as the arteriovenous difference (AVd) in mediator concentration across the airway for each level of contraction. PAF caused dose-related active tracheal tension to a maximum of 37.2 +/- 5.4 g/cm (10(-6) mol PAF). The AVd in 5-HT increased linearly from 0.20 +/- 0.05 (10(-9) mol PAF) to 3.5 +/- 0.3 ng/ml (10(-6) mol PAF) (P less than 0.005). In contrast, the AVd in histamine was insignificant and did not change with increasing doses of PAF. A positive correlation was obtained between the AVd in 5-HT and active tracheal tension (r = 0.92, P less than 0.001); there was no correlation between AVd in histamine and active tension (r = -0.16). PAF-induced parasympathetic activation was not mediated by 5-HT; contraction elicited by exogenous 5-HT was not affected by muscarinic blockade. We conclude that nonparasympathetically mediated contraction elicited acutely by PAF in dogs results at least in part from secondary release of serotonin and is not mediated by histamine.

Distribution of bronchoconstrictor responses in isolated-perfused rat lung

We studied the effects of bronchoconstrictor stimuli administered selectively through isolated-perfused preparations of the bronchial and pulmonary circulations of 80 Sprague-Dawley rats. Dose-related contraction was elicited with infusion of acetylcholine (ACh), histamine, and serotonin (5-HT). Bolus infusion of 10(-5) mol ACh caused a 3.5-fold increase in pulmonary resistance (RL) after infusion into the pulmonary circulation (PC) and a 2.5-fold increase in the bronchial circulation (BC) (P less than 0.05 vs. control) that was blocked selectively in each circulation with atropine. Administration of 10(-5) mol 5-HT into the BC caused only a 45% increase in RL; the same dose of 5-HT caused a 5.1-fold increase in RL in the PC. A biphasic (increase at lower doses/decrease at higher doses) change in RL was elicited by histamine that was converted to dose-related constriction after H2-receptor blockade with cimetidine in both BC and PC. Response to exogenous ACh remained viable for greater than 5 h. Infusion of the mast cell degranulating agent, compound 48/80 (48/80), caused increase in RL that corresponded to quantitative recovery of histamine in the perfusates of both BC and PC. Histamine concentration in the perfusate increased from 47.2 +/- 31.8 (base line) to 624 +/- 60.1 ng/ml (2-fold increase in RL) in the BC and from 38.3 +/- 17.7 (base line) to 294.4 +/- 38.1 ng/ml (50% increase in RL) in the PC (P less than 0.001 vs. baseline concentration) after a 0.1-mg/ml dose of 48/80.(ABSTRACT TRUNCATED AT 250 WORDS)