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Cytokine profiling of pulmonary aspergillosis.

Aspergillus fumigatus is ubiquitous and yet causes invasive, chronic and allergic disease of the lung. Chronic cavitary pulmonary aspergillosis (CCPA) is a slowly destructive form of pulmonary aspergillosis, without immunocompromise. We hypothesized that CCPA cytokine gene polymorphisms would differ from patients with allergic bronchopulmonary aspergillosis (ABPA) and uninfected controls. We have profiled functional cytokine gene polymorphisms for interleukin (IL)-10, IL-15, transforming growth factors (TGF)-beta1, tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma in patients with CCPA (n = 24) who were compared with other forms of aspergillosis (mostly ABPA) (n = 15) and with ethnically matched controls (n = 65-330). Results are described with reference to the high-producing genotype in each case. Susceptibility to aspergillosis (all patients compared with normal controls) was associated with higher frequency of the IL-15 +13689*A allele (OR = 2.37, P = 0.0028) and A/A genotype (chi(2) = 10.31, P < 0.001), with a lower frequency of the TNF-alpha-308*A/A genotype (chi(2) = 11.05, P < 0.01). Within the aspergillosis patients, CCPA is associated with lower frequency of the IL-10 -1082*G allele (OR = 0.38, P = 0.0006) and G/G genotype (chi(2) = 22.45, P < 0.001) and with a lower frequency of the TGF-beta1 +869 *T allele (OR +0.42, P < 0.0029) and T/T genotype (chi(2) = 17.82, P < 0.001) compared with non-CCPA patients and normal controls. Patients infected with Aspergillus appear to be higher producers of IL-15, a Th2-promoting cytokine, and lower producers of TNF-alpha, a cytokine central in protective responses. CCPA occurs in patients who are genetically lower producers of both IL-10 and TGF-beta1. As these cytokines are regulatory and anti-inflammatory, CCPA may be a consequence of poor inflammatory response control in the lung.

Adult↗

Comprehensive identification and analysis of clusters of tandemly duplicated genes reveal their contributions to adaptive evolution of green plants.

Tandem gene duplication occurred more frequently compared with the episodic whole-genome duplication (WGD), providing a continuous supply of genetic material for evolutionary innovation and adaptation to changing environments. The rising roles of clusters of tandemly duplicated genes (CTDGs) in the evolution of phenotypic diversity have been unraveled in mammals. However, the content and biological roles of CTDGs remain largely unknown in plants. Here, we comprehensively identified CTDGs in 220 published plant genomes representing major lineages of green plants. The number of CTDGs showed great variation across taxa, ranging from 0 to 6028. The size of CTDGs varied from 2 to 47 genes, with small clusters containing two members predominating. Interestingly, significant expansion of CTDGs was found in early-diverging land plants and is closely associated with the evolution of key traits (e.g., ABA response, plant cuticle, UV-B resistance) required for plants to conquer terrestrial environments. Functional enrichment analysis revealed conserved and specialized functional profiles among different sizes of CTDGs in both Arabidopsis thaliana and the bryophyte Physcomitrium patens. Small CTDGs were enriched in fundamental stress responses, including protein modification, signal transduction, and responses to diverse stress stimuli, while large CTDGs were enriched in more sophisticated processes such as plant hormone biosynthesis and signaling, plant-microbe interactions, and reproductive processes. Expression pattern analyses of CTDGs under different stress conditions in A. thaliana and P. patens revealed that the highest number of CTDGs showed differential expression under drought stress, suggesting important roles of CTDGs in the evolution of desiccation tolerance in early land plants. The results of this study provide new additions to our knowledge about the abundance of CTDGs across green plants and reveal their important contributions to enable plants to overcome stressful environments on land.

Gene Duplication↗

Differential actions of antiparkinson agents at multiple classes of monoaminergic receptor. III. Agonist and antagonist properties at serotonin, 5-HT(1) and 5-HT(2), receptor subtypes.

Although certain antiparkinson agents interact with serotonin (5-HT) receptors, little information is available concerning functional actions. Herein, we characterized efficacies of apomorphine, bromocriptine, cabergoline, lisuride, piribedil, pergolide, roxindole, and terguride at human (h)5-HT(1A), h5-HT(1B), and h5-HT(1D) receptors [guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPgammaS) binding], and at h5-HT(2A), h5-HT(2B), and h5-HT(2C) receptors (depletion of membrane-bound [(3)H]phosphatydilinositol). All drugs stimulated h5-HT(1A) receptors with efficacies (compared with 5-HT, 100%) ranging from modest (apomorphine, 35%) to high (cabergoline, 93%). At h5-HT(1B) receptors, efficacies varied from mild (terguride, 37%) to marked (cabergoline, 102%) and potencies were modest (pEC(50) values of 5.8-7.6): h5-HT(1D) sites were activated with a similar range of efficacies and greater potency (7.1-8.5). Piribedil and apomorphine were inactive at h5-HT(1B) and h5-HT(1D) receptors. At h5-HT(2A) receptors, terguride, lisuride, bromocriptine, cabergoline, and pergolide displayed potent (7.6-8.8) agonist properties (49-103%), whereas apomorphine and roxindole were antagonists and piribedil was inactive. Only pergolide (113%/8.2) and cabergoline (123%/8.6) displayed pronounced agonist properties at h5-HT(2B) receptors. At 5-HT(2C) receptors, lisuride, bromocriptine, pergolide, and cabergoline were efficacious (75-96%) agonists, apomorphine and terguride were antagonists, and piribedil was inactive. MDL100,907 and SB242,084, selective antagonists at 5-HT(2A) and 5-HT(2C) receptors, respectively, abolished these actions of pergolide, cabergoline, and bromocriptine. In conclusion, antiparkinson agents display markedly different patterns of agonist and antagonist properties at multiple 5-HT receptor subtypes. Although all show modest (agonist) activity at 5-HT(1A) sites, their contrasting actions at 5-HT(2A) and 5-HT(2C) sites may be of particular significance to their functional profiles in vivo.

Animals↗

Blood clearance and activity of erythrocyte-coupled fibrinolytics.

Conjugating tissue-type plasminogen activator (tPA) to red blood cells (RBCs) endows it with features useful for thromboprophylaxis. However, the optimal intensity and duration of thromboprophylaxis vary among clinical settings. To assess how the intrinsic properties of a plasminogen activator (PA) affect functions of the corresponding RBC/PA conjugate, we coupled equal amounts of tPA or Retavase (rPA; a variant with an extended circulation time, lower fibrin affinity, and greater susceptibility to PA inhibitors). Conjugation to RBC markedly prolonged the circulation of each PA in rats and mice, without detrimental effects on carrier RBC. The initial blood clearance of RBC/tPA was faster than RBC/rPA, yet it exerted greater fibrinolytic activity, in part due to greater resistance of tPA and RBC/tPA to plasma inhibitors versus rPA and RBC/rPA observed in vitro. Soluble and RBC-coupled tPA and rPA exerted the same amidolytic activity, yet RBC/tPA lysed fibrin clots more effectively than RBC/rPA, notwithstanding comparable fibrinolytic activity of their soluble counterparts. Conjugation to RBC suppressed rPA's ability to be activated by fibrin, whereas the fibrin activation of RBC-coupled tPA was not hindered. Therefore, the functional profile of RBC/PA is influenced by: pharmacokinetic features provided by carrier RBC (e.g., prolonged circulation), intrinsic PA features (e.g., clearance rate, resistance to inhibitors), and changes imposed by conjugation to RBC (e.g., loss of cofactor stimulation). These factors, different from those guiding the design of soluble PA for lysis of existing clots, can be exploited in the rational design of RBC/PA tailored for specific prophylactic indications.

Animals↗

Different vasoactive intestinal polypeptide receptor domains are involved in the selective recognition of two VPAC(2)-selective ligands.

A vasoactive intestinal polypeptide (VIP) analog, acylated on the amino-terminal histidine by hexanoic acid (C(6)-VIP), behaved as a VPAC(2) preferring agonist in binding and functional studies on human VIP receptors, and radioiodinated C(6)-VIP was a suitable ligand for binding studies on wild-type and chimeric receptors. We evaluated the properties of C(6)-VIP, its analog AcHis(1)-VIP, and the VPAC(2)-selective agonist Ro 25-1553 on the wild-type VPAC(1) and VPAC(2) receptors and on the chimeric receptors exchanging the different domains between both receptors. VIP had a normal affinity and efficacy on the chimeras starting with the amino-terminal VPAC(2) receptor sequence. The binding and functional profile of these chimeric receptors suggested that the high affinity of Ro 25-1553 for VPAC(2) receptors is supported by the amino-terminal extracellular domain, whereas the ability to prefer C(6)-VIP over VIP is supported by the VPAC(2) fifth transmembrane (TM5)-EC(3) receptor domain. These results further support the hypothesis that the central and carboxyl-terminal regions of the peptide (modified in RO 25-1553) recognize the extracellular amino-terminal region domain, whereas the amino-terminal VIP amino acids bind to the TM receptor core. VIP had a reduced affinity and efficacy on the N-VPAC(1)/VPAC(2) and on the N-->EC(2)-VPAC(1)/VPAC(2) chimeric receptors. C(6)-VIP behaved as a high-affinity agonist on these constructions. The antagonists [AcHis(1),D-Phe(2),Lys(15),Arg(16), Leu(27)]VIP(3-7)/GRF(8-27) and VIP(5-27) had comparable affinities for the wild-type receptors and for the two latter chimeras, supporting the hypothesis that these chimeras were properly folded but unable to reach the high-agonist-affinity, active receptor conformation in response to VIP binding.

Animals↗

Prior vaccination prevents overactivation of innate immune responses during COVID-19 breakthrough infection.

At this stage in the COVID-19 pandemic, most infections are "breakthrough" infections that occur in individuals with prior severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure. To refine long-term vaccine strategies against emerging variants, we examined both innate and adaptive immunity in breakthrough infections. We performed single-cell transcriptomic, proteomic, and functional profiling of primary and breakthrough infections to compare immune responses from unvaccinated and vaccinated individuals during the SARS-CoV-2 Delta wave. Breakthrough infections were characterized by a less activated transcriptomic profile in monocytes and natural killer cells, with induction of pathways limiting monocyte migratory potential and natural killer cell proliferation. Furthermore, we observed a female-specific increase in transcriptomic and proteomic activation of multiple innate immune cell subsets during breakthrough infections. These insights suggest that prior SARS-CoV-2 vaccination prevents overactivation of innate immune responses during breakthrough infections with discernible sex-specific patterns and underscore the potential of harnessing vaccines in mitigating pathologic immune responses resulting from overactivation.

Immunity, Innate↗

Rapid memory CD8+ T-lymphocyte induction through priming with recombinant Mycobacterium smegmatis.

The most promising vaccine strategies for the induction of cytotoxic-T-lymphocyte responses have been heterologous prime/boost regimens employing a plasmid DNA prime and a live recombinant-vector boost. The priming immunogen in these regimens must elicit antigen-specific memory CD8+ T lymphocytes that will expand following the boosting immunization. Because plasmid DNA immunogens are expensive and their immunogenicity has proven disappointing in human clinical trials, we have been exploring novel priming immunogens that might be used in heterologous immunization regimens. Here we show that priming with a prototype recombinant Mycobacterium smegmatis strain expressing human immunodeficiency virus type 1 (HIV-1) gp120-elicited CD4+ T lymphocytes with a functional profile of helper cells as well as a CD8+ T-lymphocyte population. These CD8+ T lymphocytes rapidly differentiated to memory cells, defined on the basis of their cytokine profile and expression of CD62L and CD27. Moreover, these recombinant-mycobacterium-induced T lymphocytes rapidly expanded following boosting with a recombinant adenovirus expressing HIV-1 Env to gp120-specific CD8+ T lymphocytes. This work demonstrates a remarkable skewing of recombinant-mycobacterium-induced T lymphocytes to durable antigen-specific memory CD8+ T cells and suggests that such immunogens might be used as priming vectors in prime/boost vaccination regimens for the induction of cellular immune responses.

AIDS Vaccines↗

Envelope-dependent restriction of human immunodeficiency virus type 1 spreading in CD4(+) T lymphocytes: R5 but not X4 viruses replicate in the absence of T-cell receptor restimulation.

The human immunodeficiency virus (HIV) replicates in activated CD4(+) T lymphocytes. However, only CD4(+) Th2 and Th0, but not Th1, CD4(+) T-cell clones have been reported to efficiently support HIV-1 replication. This dichotomous pattern was further investigated in the present study in Th1, Th2, or Th0 cell lines derived from umbilical human cord blood and in T-cell clones obtained from the peripheral blood mononuclear cells (PBMC) of healthy adults. Both primary and laboratory-adapted HIV-1 strains with CCR5 as the exclusive entry coreceptor (R5 viruses) efficiently replicated in Th1, Th2, and Th0 cells. In sharp contrast, CXCR4-dependent (X4) viruses poorly replicated in both polarized and unpolarized CD4(+) T cells, including adults' PBMC infected several days after mitogenic stimulation. Unlike the X4 HIV-1(NL4-3), a chimera in which the env gene had been replaced with that of the R5 HIV-1(NL(AD8)), efficiently replicated in both Th1 and Th2 cells. This X4-dependent restriction of HIV replication was not explained by either the absence of functional CXCR4 on the cell surface or by the inefficient viral entry and reverse transcription. T-cell receptor stimulation by anti-CD3 monoclonal antibodies fully rescued X4 HIV-1 replication in both Th1 and Th2 cells, whereas it did not alter the extent and kinetics of R5 HIV-1 spreading. Thus, R5 HIVs show a replicative advantage in comparison to X4 viruses in their ability to efficiently propagate among suboptimally activated T lymphocytes, regardless of their polarized or unpolarized functional profiles. This observation may help to explain the absolute predominance of R5 HIVs over X4 viruses observed after viral transmission and during early-stage disease.

Adult↗

Meta-CD: a metagenomic sequencing coverage and depth calculator for target species.

Metagenomic Coverage and Depth Calculator (Meta-CD) is a convenient, biologist-friendly tool for determining coverage and depth to enhance taxonomic detection, functional profiling, and metagenome-assembled genome (MAG) recovery in metagenomics. It supports experimental design and post-sequencing analysis, modeling how genome size, relative abundance, sequencing depth, and DNA quantity influence detection of target species.

metagenomics↗

Clinical and urodynamic studies in 100 elderly incontinent patients.

Clinical details were noted and urodynamic studies carried out on 100 elderly patients referred to an incontinence clinic, of whom 48 attended as day patients. Thirty patients had no problem apart from their incontinence, and only 38 had a clinically detectable neurological lesion. The average mental orientation score in 48 of the patients was 7.6, 23 patients scoring the top score of 10. Most patients were mobile without assistance from another person. Patients could be placed into one of four diagnostic groups according to the appearance of the cystometric tracings, but no bladder capacity or pressure was characteristic of any group. The maximum urethral closure pressure and functional profile length were similar for each group within each sex. There was no correlation between clinical and urodynamic findings, yet each of the four diagnostic categories have different therapeutic implications. It is concluded that urodynamic investigation is necessary in elderly incontinent patients before treatment.

Aged↗

Motor neurone disease: a hospice perspective.

OBJECTIVE: To describe and evaluate the management of patients with motor neurone disease from the perspective of a hospice. DESIGN: Retrospective analysis of hospice medical and nursing notes. SETTING: Established 62 bed teaching and research hospice. SUBJECTS: 124 patients with motor neurone disease cared for by the hospice between January 1980 and November 1990. MAIN OUTCOME MEASURES: Patient profile; functional status; symptom control and use of opioids; insight; mode and management of death. RESULTS: 124 patients (67 women, 57 men) had a mean age 63.9 years. The median length of admission was 61.5 days (range 1 to 2147). 84 patients (68%) were aware of their diagnosis and its implications when first seen by a hospice doctor. Functionally, the patients were very dependent. Symptoms such as pain, dyspnoea, and insomnia were major problems that responded well to opioids. Many patients were noted to deteriorate "suddenly," and in 58% of cases death occurred within 24 hours of this deterioration. When dying, 106 patients (94%) were peaceful and settled. 101 patients (89%) received opioids during this dying period. No patient chocked to death. CONCLUSIONS: Although motor neurone disease is an uncommon disorder, many of its symptoms occur commonly in medical practice and must be actively treated. Opioids are both safe and effective for such treatment. The term chocking is both inaccurate and inappropriate in describing the cause of death in motor neurone disease and its use should be abandoned.

Adult↗

A comparison of three measures of perceived distress: results from a study of angina patients in general practice in Northern Ireland.

OBJECTIVE: To establish the effect of health education on the level of distress felt by patients with angina and to compare the results obtained using different measures. DESIGN: Randomised controlled trial of personal health education given every four months. SETTING: Eighteen general practices in the greater Belfast area. SUBJECTS: These comprised 688 patients aged less than 75 years and known to have had angina for at least six months: 342 were randomised to receive education and 346 no education. MAIN OUTCOME MEASURES: These were the Nottingham health profile (NHP), functional limitation profile (FLP), and a simple categorical scale (SCS). RESULTS: The intervention group showed a statistically significant improvement in health relative to the control group in terms of physical mobility and social isolation using the NHP. In terms of overall wellbeing, both the NHP and SCS results showed the intervention group had experienced statistically significant improvements in health relative to the control group. Results obtained using the NHP, FLP, and SCS were found to be correlated regardless of whether weighted or unweighted scores were used. CONCLUSION: The intervention produced a significant improvement in health status. Results from different survey instruments were correlated using both weighted and unweighted scores. An SCS was capable of detecting the improvement in health status.

Aged↗

Specific patterns of cognitive impairment in patients with idiopathic normal pressure hydrocephalus and Alzheimer's disease: a pilot study.

OBJECTIVES: Eleven patients with idiopathic normal pressure hydrocephalus (NPH) were selected from an initial cohort of 43 patients. The patients with NPH fell into two distinctive subgroups: preshunt, group 1 (n=5) scored less than 24 on the mini mental state examination (MMSE) and were classified as demented and group 2 (n=6) scored 24 or above on the MMSE and were classified as non-demented. METHODS: All patients were neuropsychologically assessed on two occasions: preshunt and then again 6 months postshunt. Group 1 completed the mini mental state examination (MMSE) and the Kendrick object learning test (KOLT). In addition to the MMSE and KOLT, group 2 completed further tasks including verbal fluency and memory and attentional tasks from the CANTAB battery. Nine of the 11 patients also underwent postshunt MRI. RESULTS: Group 1, who, preshunt, performed in the dementing range on both the MMSE and KOLT, showed a significant postoperative recovery, with all patients now scoring within the normal non-demented range. Group 2, although showing no signs of dementia according to the MMSE and KOLT either preshunt or postshunt, did show a specific pattern of impairment on tests sensitive to frontostriatal dysfunction compared with healthy volunteers, and this pattern remained postoperatively. Importantly, this pattern is distinct from that exhibited by patients with mild Alzheimer's disease. Eight of the nine patterns of structural damage corresponded well to cognitive performance. CONCLUSIONS: These findings are useful for three main reasons: (1) they detail the structural and functional profile of impairment seen in NPH, (2) they demonstrate the heterogeneity found in this population and show how severity of initial cognitive impairment can affect outcome postshunt, and (3) they may inform and provide a means of monitoring the cognitive outcome of new procedures in shunt surgery.

Aged↗

Importance of sensitivity to change as a criterion for selecting health status measures.

OBJECTIVE: To assess the sensitivity to change over time of four health status instruments in relation to patients with rheumatoid arthritis. DESIGN: Observational three month study of four self assessed instruments (arthritis impact measurement scales (AIMS), health assessment questionnaire (HAQ), Nottingham health profile (NHP), functional limitations profile (FLP)). SETTING: One rheumatology unit. PATIENTS: 101 patients with definite or classic rheumatoid arthritis. MAIN MEASURES: Change scores for dimensions of instruments, as determined by effect size (mean change in score/baseline standard deviation of variable) and conventional rheumatological measures, at baseline and after three months. RESULTS: Change scores for comparable dimensions (mobility, activities of daily living, household, pain, mood or emotion, and social scales) of the instruments were compared among 30 patients who considered their health status to have improved over three months. For all dimensions of health status the magnitude of change varied considerably according to the instrument. Maximum range in effect size was for social scales (AIMS 0.06, NHP 0.24, FLP 0.60). No single instrument seemed consistently to show the most change over all dimensions. CONCLUSION: Selection of health status instruments for audit or evaluation may have a considerable impact on the pattern of results obtained, and the "responsiveness" of such scales should be as carefully examined as their reliability and acceptability when selecting outcome measures.

Activities of Daily Living↗

Nucleus-specific abnormalities of GABAergic synaptic transmission in a genetic model of absence seizures.

Human and experimental studies indicate that molecular genetic changes in GABA(A) receptors may underlie the expression of spike-and-waves discharges (SWDs) occurring during absence seizures. However, the full spectrum of the genetic defects underlying these seizures has only been partially elucidated, the expression and functional profiles of putative abnormal protein(s) within the thalamocortical network are undefined, and the pathophysiological mechanism(s) by which these proteins would lead to absence paroxysms are poorly understood. Here we investigated GABA(A) inhibitory postsynaptic currents (IPSCs) in key thalamocortical areas, i.e., the somatosensory cortex, ventrobasal thalamus (VB) and nucleus reticularis thalami (NRT), in preseizure genetic absence epilepsy rats from Strasbourg (GAERS), a well-established genetic model of typical absence seizures that shows no additional neurological abnormalities, and compared their properties to age-matched non-epileptic controls (NECs). Miniature GABA(A) IPSCs of VB and cortical layers II/III neurons were similar in GAERS and NEC, whereas in GAERS NRT neurons they had 25% larger amplitude, 40% faster decay. In addition, baclofen was significantly less effective in decreasing the frequency of NRT mIPSCs in GAERS than in NEC, whereas no difference was observed for cortical and VB mIPSCS between the two strains. Paired-pulse depression was 45% smaller in GAERS NRT, but not in VB, and was insensitive to GABA(B) antagonists. These results point to subtle, nucleus-specific, GABA(A) receptor abnormalities underlying SWDs of typical absence seizures rather than a full block of these receptors across the whole thalamocortical network, and their occurrence prior to seizure onset suggests that they might be of epileptogenic significance.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

Nuclear hormone and orphan receptors: their role in neuronal differentiation and cytoprotection and in the pathogenesis of Parkinson's disease.

Human nuclear hormone receptors (NHR) and orphan receptors (NOR) act as transcription factors in response to a wide range of circulating hormones and unknown ligands. A role for NHR and NOR in disorders of the subcortical dopaminergic pathways such as Parkinson's disease (PD) is suggested by a wealth of recent data including experimental observations. Both classes of receptors promote the formation of specific neuronal identities, tissue patterning during embryonic development and the maturation of vulnerable monoaminergic and cholinergic neurons. NHR and NOR are also known to exert a neuroprotective function on adult neurons. The scope of this review is to revisit the functional profile of these receptors with particular reference to their activity in the development of selected neuronal populations relevant to the pathophysiology of PD and to discuss how they may relate to the neuropathological and clinical expression of the disease.

Animals↗

The natural course of schizophrenia and psychopathological predictors of outcome. A community-based cohort study.

The natural course of schizophrenia is extremely heterogeneous and generally considered unpredictable. This prospective research investigated the natural course of schizophrenia in a community-based population linked to an Italian Mental Health Center, looking for the identification of psychopathological predictors of outcome. Forty schizophrenic patients were assessed at baseline in a stabilized phase of illness with clinical scales of psychopathology and social functioning and afterwards were followed up for 36 months. All of them were treated with antipsychotic drugs. According to their symptoms and function scores patients were empirically classified into three groups with a cluster analysis: a group characterized by low symptoms and good functioning, a group with high symptoms and poor functioning and an intermediate group. A crosstabs analysis revealed that the empirical classification correctly predicted long-term outcome. A survival analysis with comparison of distributions (Wilcoxon Gehan test) also revealed significant differences in terms of hospital admission and occurrence of alcohol-related diagnosis across groups. This study suggests that the long-term outcome in schizophrenic patients followed by a community-based mental health service is generally poor and multifaceted. However, outcome may be predicted on the basis of the psychopathological and social functioning profile assessed in a stabilized phase of illness defined with operational criteria.

Adult↗

Characterization of CCKA receptor mediated pepsinogen secretion in porcine chief cells.

Cholecystokinin octapeptide (CCK-8s) is an endogenous stimulus of gastric pepsinogen secretion. Previous studies with isolated guinea pig chief cells indicated that this process is mediated through the CCKA receptor subtype, with an additional contribution from CCKB receptors. For comparison, we examined the mechanism of CCK-8s stimulated pepsinogen secretion in a larger nonrodent species, using highly enriched porcine chief cells as a functional in vitro model. Porcine chief cells responded weakly to stimulation by CCK-8s alone, but the efficacy was markedly enhanced in the presence of 10 mumol l-1 forskolin. Under these conditions, pepsinogen secretion was potently stimulated by CCK-8s and the CCKA receptor selective heptapeptide, A-71,378 (EC50 = 4.7 and 33 nmol l-1), but not by CCKB receptor selective agonists. The prototype CCKA receptor selective antagonist L-364,718 blocked pepsinogen secretion with approximately 2,000-fold higher affinity than the CCKB receptor selective analogue, L-365,260. This functional profile was consistent with the affinity rank order of all tested compounds at CCKA-receptor-like [125I]-BH-CCK-8s binding sites in the porcine gastric mucosa. Comparison with cloned CCKA receptors from other species revealed that the receptors mediating pepsinogen secretion in the pig have similar pharmacology, possibly with slight differences in agonist potencies. In contrast to the guinea pig, porcine CCKB receptors appear to have no direct role in pepsinogen secretion.

Animals↗