Do socio-demographic characteristics and/or health status explain the magnitude of differences between patient and general public utility values? A chronic low back pain patients case study.

BACKGROUND: Utility values can be obtained from different respondent groups, including patients and members of the general public. Evidence suggests that patient values are typically higher than general public values. This study explores whether the magnitude of disagreement between both values can be explained by socio-demographic characteristics and/or health status. METHODS: Data of 5037 chronic low back pain patients were used. Self-reported EQ-VAS was employed as a proxy of patients' preference for their own health state. General public values for the patients' EQ-5D-3L health states were obtained using the Dutch VAS-based tariff. The difference between patient and general public values was assessed using a paired t-test. Subsequently, this difference was used as a dependent variable and regressed upon dummy variables of socio-demographic and health status characteristics. Coefficients represented age, gender, education level, social support, back pain intensity, leg pain intensity, functional status, comorbidities, catastrophizing, and treatment expectations. RESULTS: Patient values were higher than general public values (0.069; 95%CI:0.063-0.076). The magnitude of disagreement between both values was associated with age, gender, education level, social support, functional status, and comorbidities, but not with back pain intensity, leg pain intensity, catastrophizing, and treatment expectations. CONCLUSIONS: Patients were found to value their own health status higher than members of the general public. The magnitude of disagreement between both values was found to differ by various socio-demographic and/or health status characteristics. This suggest that patient characteristics account for a relevant fraction of the identified disagreements between patient and general public values, and that mechanisms thought to be responsible for these disagreements, such as adaptation and response shift, have a differential impact across patient sub-groups.

Genetic testing for BRCA1 and BRCA2 in the Province of Ontario.

In 2001, genetic testing for BRCA1 and BRCA2 was introduced in Ontario, for women at high-risk of breast or ovarian cancer. To date over 30,000 individuals have been tested throughout Ontario. Testing was offered to all Ontario residents who were eligible under any of 13 criteria. We report the results of tests conducted at Mount Sinai Hospital from 2007 to 2014. A total of 4726 individuals were tested, 764 (16.2%) were found to carry a pathogenic variant (mutation). Among 3684 women and men who underwent testing without a known familial BRCA mutation, 331 (9.0%) were found to carry a mutation. Among 1042 women and men tested for a known family mutation, 433 (41.6%) were positive. There were 603 female mutation carriers, of these, 303 were affected with breast or ovarian cancer (50%) and 16 with another cancer (2.3%). Of 284 unaffected female carriers, 242 (85%) were tested for a known family mutation and 42 (15%) were the first person in the family to be tested. By placing greater emphasis on recruiting unaffected female relatives of known mutation carriers for testing, greater than one-half of newly identified carriers will be unaffected.

Seasonal recurrence of food bolus obstruction in eosinophilic esophagitis.

BACKGROUND: Eosinophilic esophagitis (EoE) is a newly recognised condition that is apparently increasing in prevalence, and the aetiology is poorly understood. The role of aeroallergens in EoE is controversial, given the success of dietary therapy. Massive aeroallergen exposure leading to food bolus obstruction events (FBOE) has been described, and the diagnosis of EoE by esophageal biopsy noted to be more common in the pollen season according to previous case series. AIM: To determine if a seasonal variation and a geographical variation occurred in EoE presenting as FBOE in adults, and to track the prevalence of FBOE and EoE over time. METHOD: A retrospective case-control study analysis was performed from January 2002 to January 2012 to identify all FBOE in adults presenting to five tertiary hospitals in Melbourne, Australia. Endoscopy, histopathological reports, case notes and blood tests were examined, and postcodes recorded. Records of pollen counts were obtained. Cases were defined according to esophageal biopsy and grouped based on month of diagnosis. All other causes of FBOE served as controls. RESULTS: One thousand, one hundred and thirty-two FBOE were identified. Biopsies were only performed in 278 of these cases, and 85 patients were found to have EoE after biopsy. Patients with EoE were younger (mean age 38 years, range 18-72) compared with those with alternative diagnosis (mean age 64.4 range 22-92), more likely to be male (M : F = 4:1 compared with 1.68:1 ) and had a higher eosinophil count in venous blood. Overall no seasonality was demonstrated in FBOE secondary to any diagnosis, although the six cases of recurrent FBOE secondary to EoE mainly occurred in the grass pollen season in subsequent years. FBOE cases were evenly distributed throughout metropolitan Melbourne irrespective of population density. EoE as a percentage of FBOE increased over time. CONCLUSION: Seasonal aeroallergens may be important for a subgroup of patients with EoE presenting as recurrent FBOE. Esophageal biopsies are performed in a minority of patients, representing a significant departure from ideal management and contributing to recurrent unnecessary FBOE. EoE is an increasingly important cause of FBOE.

Improvements in hippocampal-dependent memory and microglial infiltration with calorie restriction and gastric bypass surgery, but not with vertical sleeve gastrectomy.

BACKGROUND: Much recent evidence suggest that obesity and related comorbidities contribute to cognitive decline, including the development of non age-related dementia and Alzheimer's disease. Obesity is a serious threat to public health, and few treatments offer proven long-term weight loss. In fact, bariatric surgery remains the most effective long-term therapy to reduce weight and alleviate other aspects of the metabolic syndrome (MetS). Unlike the demonstrated benefits of caloric restriction to prevent weight gain, few if any studies have compared various means of weight loss on central nervous system function and hippocampal-dependent cognitive processes. DESIGN AND RESULTS: Our studies comprise the first direct comparisons of caloric restriction to two bariatric surgeries (Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG)) on cognitive function. Weight loss following caloric restriction, RYGB and VSG was associated with generalized improvements in metabolic health and hippocampal-dependent learning, as measured in the radial arm maze and spontaneous alternation tests. However, VSG-treated rats exhibited deficits on spatial learning tasks in the Morris water maze. In addition, whereas VSG animals had elevated hippocampal inflammation, comparable to that of obese controls, RYGB and calorie-restricted (pair-fed, PF) controls exhibited an amelioration of inflammation, as measured by the microglial protein ionized calcium binding adaptor molecule 1 (IBA1). We also assessed whether GHR (ghrelin) replacement would attenuate hippocampal inflammation in VSG, as post-surgical GHR levels are significantly reduced in VSG relative to RYGB and PF rats. However, GHR treatment did not attenuate the hippocampal inflammation. CONCLUSION: Although VSG was comparably effective at reducing body weight and improving glucose regulation as RYGB, VSG did not appear to confer an equal benefit on cognitive function and markers of inflammation.

Preventing ovarian cancer through genetic testing: a population-based study.

Genetic testing for BRCA1 and BRCA2 gene mutations, in conjunction with preventive salpingo-oophorectomy for mutation carriers, may be used to prevent a proportion of invasive ovarian cancers ('personalized medicine'). We evaluated the potential utility of this approach at a population level by reviewing the pedigree information and genetic test results from 1342 ovarian cancer patients in Ontario. Of the 1342 patients tested, 176 patients had a BRCA1 or BRCA2 mutation; of these, 48 women would have qualified for testing prior to the development of cancer based on the eligibility criteria in place for the province of Ontario. In summary, 48 of 1342 unselected cases of ovarian cancer (3.6%) might have been prevented if genetic testing criteria were universally applied to all women in Ontario at risk for ovarian cancer.

Citation impact and reach of the IOC sport and exercise medicine consensus statements.

Background: Research evidence is commonly compiled into expert-agreed consensus statements or guidelines, with an increasing trend towards their publication in peer-reviewed journals. Prominent among these has been the publication of several International Olympic Committee (IOC) tatements to help inform sport and exercise medicine (SEM) practice. This study aimed to assess the citation impact and reach of the IOC statements published between 2003 and 2020. Method: Bibliometric analysis focused on identifying core publications (original statement and linked publications) and quantifying their academic citations (number and Field-Weighted Citation Impact (FWCI)) in journal articles up to February 2022. The analysis includes descriptive data on the country of IOC statement authorship affiliations, where they were published and by whom. The extent to which the IOC statements have been cited in the peer-reviewed literature is presented, together with information about the country of authorship of the citing papers as a measure of international academic reach. Results: 29 IOC statements were composed of 61 core publications. The IOC statements have had 9535 citations from 7863 citing publications. Individual FWCI ranged from 1.2 to 24.3 for core publications. The IOC statements were coauthored by multiple authors, mostly affiliated to countries with well-resourced SEM Authors of citing publications reflected the same geographical regions (ie, the USA, Canada, Australia, UK and western Europe.). Conclusion: Disseminating the IOC statements as open access papers in peer-reviewed journals has resulted in strong citation impact. However, this impact is centred on well-resourced academic circles that may not represent the diversity of SEM. Further research is required to identify if, and to what extent, the IOC statements have impacted SEM practice worldwide.

The pathological response to DNA damage does not contribute to p53-mediated tumour suppression.

The p53 protein has a highly evolutionarily conserved role in metazoans as 'guardian of the genome', mediating cell-cycle arrest and apoptosis in response to genotoxic injury. In large, long-lived animals with substantial somatic regenerative capacity, such as vertebrates, p53 is an important tumour suppressor--an attribute thought to stem directly from its induction of death or arrest in mutant cells with damaged or unstable genomes. Chemotherapy and radiation exposure both induce widespread p53-dependent DNA damage. This triggers potentially lethal pathologies that are generally deemed an unfortunate but unavoidable consequence of the role p53 has in tumour suppression. Here we show, using a mouse model in which p53 status can be reversibly switched in vivo between functional and inactive states, that the p53-mediated pathological response to whole-body irradiation, a prototypical genotoxic carcinogen, is irrelevant for suppression of radiation-induced lymphoma. In contrast, delaying the restoration of p53 function until the acute radiation response has subsided abrogates all of the radiation-induced pathology yet preserves much of the protection from lymphoma. Such protection is absolutely dependent on p19(ARF)--a tumour suppressor induced not by DNA damage, but by oncogenic disruption of the cell cycle.

Hypoxia-driven metabolic reprogramming of adipocytes fuels cancer cell proliferation.

Objective: Obesity increases the risk of certain cancers, especially tumours that reside close to adipose tissue (breast and ovarian metastasis in the omentum). The obesogenic and tumour micro-environment share a common pathogenic feature, oxygen deprivation (hypoxia). Here we test how hypoxia changes the metabolome of adipocytes to assist cancer cell growth. Methods: Human and mouse breast and ovarian cancer cell lines were co-cultured with human and mouse adipocytes respectively under normoxia or hypoxia. Proliferation and lipid uptake in cancer cells were measured by commercial assays. Metabolite changes under normoxia or hypoxia were measured in the media of human adipocytes by targeted LC/MS. Results: Hypoxic cancer-conditioned media increased lipolysis in both human and mouse adipocytes. This led to increased transfer of lipids to cancer cells and consequent increased proliferation under hypoxia. These effects were dependent on HIF1α expression in adipocytes, as mouse adipocytes lacking HIF1α showed blunted responses under hypoxic conditions. Targeted metabolomics of the human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes media revealed that culture with hypoxic-conditioned media from non-malignant mammary epithelial cells (MCF10A) can alter the adipocyte metabolome and drive proliferation of the non-malignant cells. Conclusion: Here, we show that hypoxia in the adipose-tumour microenvironment is the driving force of the lipid uptake in both mammary and ovarian cancer cells. Hypoxia can modify the adipocyte metabolome towards accelerated lipolysis, glucose deprivation and reduced ketosis. These metabolic shifts in adipocytes could assist both mammary epithelial and cancer cells to bypass the inhibitory effects of hypoxia on proliferation and thrive.

The impact of prophylactic salpingo-oophorectomy on menopausal symptoms and sexual function in women who carry a BRCA mutation.

OBJECTIVE: Prophylactic salpingo-oophorectomy is recommended to women who carry a BRCA1 or BRCA2 mutation to reduce the risks of breast, ovarian and fallopian tube cancer. We measured the impact of prophylactic salpingo-oophorectomy on menopausal symptoms and sexual functioning in women with a BRCA mutation. METHODS: Women who underwent prophylactic salpingo-oophorectomy between October 1, 2002 and June 26, 2008 for a known BRCA1 or BRCA2 mutation were invited to participate. Participants completed questionnaires before prophylactic surgery and again one year after surgery. Measures of sexual functioning and menopausal symptoms before and after surgery were compared. Satisfaction with the decision to undergo prophylactic salpingo-oophorectomy was evaluated. RESULTS: 114 women who underwent prophylactic surgery completed questionnaires before and one year after surgery. Subjects who were premenopausal at the time of surgery (n=75) experienced a significant worsening of vasomotor symptoms (hot flashes, night sweats and sweating) and a decline in sexual functioning (desire, pleasure, discomfort and habit). The increase in vasomotor symptoms and the decline in sexual functioning were mitigated by HRT, but symptoms did not return to pre-surgical levels. HRT decreased vaginal dryness and dyspareunia; however, the decrease in sexual pleasure was not alleviated by HRT. Satisfaction with the decision to undergo prophylactic salpingo-oophorectomy remained high regardless of increased vasomotor symptoms and decreased sexual function. CONCLUSIONS: Women who undergo prophylactic salpingo-oophorectomy prior to menopause experience an increase in vasomotor symptoms and a decrease in sexual functioning. These symptoms are improved by HRT, but not to pre-surgical levels.

Breast cancer risks in women with a family history of breast or ovarian cancer who have tested negative for a BRCA1 or BRCA2 mutation.

Genetic testing for mutations in BRCA1 and BRCA2 is available in Canada for women with a significant family history of breast cancer. For the majority of tested women, a BRCA1 or BRCA2 mutation is not found, and counselling regarding breast cancer risk is based on the review of the pedigree. In this prospective study, we estimate breast cancer risks in women with a family history of breast cancer and for whom the proband tested negative for a mutation in BRCA1 or BRCA2. Families with two or more breast cancers under the age of 50 years, or with three cases of breast cancer at any age, and who tested negative for a BRCA1 or BRCA2 mutation were identified. Follow-up information on cancer status was collected on all first-degree relatives of breast cancer cases. The standardised incidence ratios (SIRs) for breast cancer were calculated by dividing the observed numbers of breast cancer by the expected numbers of breast cancers, based on the rates in the provincial cancer registries. A total of 1492 women from 365 families were included in the analyses. The 1492 first-degree relatives of breast cancer cases contributed 9109 person-years of follow-up. Sixty-five women developed breast cancer, compared to 15.2 expected number (SIR=4.3). The SIR was highest for women under the age of 40 (SIR=14.9) years and decreased with increasing age. However, the absolute risk was higher for women between the age of 50 and 70 (1% per year) years than for women between 30 and 50 (0.4% per year) years of age. There was no elevated risk for ovarian, colon or any other form of cancer. Women with a significant family history of breast cancer (ie, two or more breast cancers under the age of 50 years, or three or more breast cancers at any age), but who test negative for BRCA mutations have approximately a four-fold risk of breast cancer. Women in these families may be candidates for tamoxifen chemoprevention and/or intensified breast screening with an MRI.

Breast and ovarian cancer risk perception after prophylactic salpingo-oophorectomy due to an inherited mutation in the BRCA1 or BRCA2 gene.

It is often recommended that women who carry a mutation in the BRCA1 or BRCA2 gene have their ovaries and fallopian tubes removed to reduce their risk of gynecologic cancer. The aim of this study was to evaluate women's perception of their risk of breast and ovarian cancer before and after prophylactic salpingo-oophorectomy. We surveyed 127 women who carry a BRCA1 or BRCA2 mutation and who underwent prophylactic salpingo-oophorectomy at the University Health Network, Toronto. Subjects were asked to estimate their risks of breast and ovarian cancer before and after surgery. Their perceived risks of cancers were then compared with published risks, based on their mutation status. BRCA1 carriers estimated their risk of breast cancer risk to be, on average, 69% before surgery and 41% after surgery. They estimated their risk of ovarian cancer to be 55% before surgery and 11% after surgery. BRCA2 carriers estimated their risk of breast cancer to be 69% prior to surgery and 45% after surgery and their perceived risk of ovarian cancer to be 43% before surgery and 8% after surgery. Compared with published risk figures, the perceived risk of ovarian cancer before prophylactic salpingo-oophorectomy was overestimated by 47% of BRCA1 mutation carriers and by 61% of BRCA2 mutation carriers. Most women who have undergone genetic counseling and subsequently choose prophylactic salpingo-oophorectomy accurately perceive their risk of breast cancer. However, in this study, many women overestimated their risk of ovarian cancer, particularly women who carry a BRCA2 mutation.

Regulation of cyclooxygenase 2 mRNA stability by the mitogen-activated protein kinase p38 signaling cascade.

A tetracycline-regulated reporter system was used to investigate the regulation of cyclooxygenase 2 (Cox-2) mRNA stability by the mitogen-activated protein kinase (MAPK) p38 signaling cascade. The stable beta-globin mRNA was rendered unstable by insertion of the 2, 500-nucleotide Cox-2 3' untranslated region (3' UTR). The chimeric transcript was stabilized by a constitutively active form of MAPK kinase 6, an activator of p38. This stabilization was blocked by SB203580, an inhibitor of p38, and by two different dominant negative forms of MAPK-activated protein kinase 2 (MAPKAPK-2), a kinase lying downstream of p38. Constitutively active MAPKAPK-2 was also able to stabilize chimeric beta-globin-Cox-2 transcripts. The MAPKAPK-2 substrate hsp27 may be involved in stabilization, as beta-globin-Cox-2 transcripts were partially stabilized by phosphomimetic mutant forms of hsp27. A short (123-nucleotide) fragment of the Cox-2 3' UTR was necessary and sufficient for the regulation of mRNA stability by the p38 cascade and interacted with a HeLa protein immunologically related to AU-rich element/poly(U) binding factor 1.

Flow microcalorimetric study of immobilized enzyme kinetics using the co-immobilized glucose oxidase-catalase system.

The kinetics of the bi-substrate enzyme glucose oxidase (EC 1.1.3.4) (with catalase, EC 1.11.1.6) co-immobilized on glass was studied using flow microcalorimetry. Oxygen and glucose external-internal diffusion effects were resolved.

Structural and functional determinants of Mucor miehei protease. V. Enthalpy changes upon thermal denaturation in solution of varying pH.

The thermal denaturation of Mucor meihei protease was studied as a function of pH by differential scanning calorimetry. In both citric acid-Na2HPO4 and in acetic acid-sodium acetate buffers, maximum thermal stability was at pH 4.0-4.2. However, the maximum enthalpy changes associated with the denaturation process were buffer-dependent and occurred between pH values of 4.7 and 5.7.

Enthalphy changes associated with the denaturation of collagens of different imino acid content.

The enthalpy changes associated with the denaturation of acid-soluble and insoluble collagens prepared from sheep, cod, halibut and pike skin were determined by differential scanning calorimetry. The enthalpy change associated with the soluble collagens decreased with decreasing imino acid content (from 1420 cal/mol for sheep to 736 cal/mol for cod) while the value for insoluble collagens was approximately constant at 1360 cal/mol. A possible explanation for these values in terms of the nautre of the bonds present in collagen is discussed.

Acute response to barefoot running in habitually shod males.

The aim of this study was to examine the immediate effects of barefoot (BF) running on lower limb kinematics and muscle activity in a group of habitually shod runners. Ten male runners with no prior BF or minimalist running experience performed 1-min bouts of treadmill running at 3 velocities in both shod and BF conditions. 2D video data were recorded in order to quantify ankle, knee and hip kinematics. Synchronous kinetic data were recorded from a force plate supporting the treadmill in order to quantify spatiotemporal variables. EMG data were collected from 6 lower limb muscles, quantifying recruitment patterns during discrete phases of the gait cycle. BF running resulted in significantly higher stride frequency and shorter ground contact times (P < .001). Additionally, BF running significantly reduced knee and hip range of motion but increased ankle range of motion during the absorptive phase of the stance. Alterations in ankle kinematics during BF running resulted from increased pre-activation of the medial (P < .05) and lateral (P < .01) gastrocnemius in addition to reductions in pre-activation of the tibialis anterior (P < .05). The results highlight that recruitment patterns and kinematics can change in as little as 30-s of BF running in individuals with no previous BF running experience.

Selective activation of JNK/SAPK by interleukin-1 in rabbit liver is mediated by MKK7.

Activation of jun N-terminal kinase (JNK)/stress-activated protein kinase (SAPK) by interleukin-1 (IL-1) has been reported in many cells and in rabbit liver. Here we report selective activation of JNK/SAPK, without activation of p38 or p42 mitogen-activated protein kinases (MAPKs), by IL-1 in rabbit liver. We identified an IL-1 regulated JNK/SAPK activator present in rabbit liver using S Sepharose chromatography. It was purified and immunoprecipitated by two antisera to MAP kinase kinase 7 (MKK7). It was not recognised by an antibody to MKK4. We conclude that MKK7 is the activator of JNK/SAPK activated by IL-1 in liver and that JNK/SAPK is the only MAPK activated by IL-1 in liver.

Protein kinase cascades in intracellular signalling by interleukin-I and tumour necrosis factor.

Interleukin 1 (IL-1) and tumour necrosis factor (TNF) are major mediators of inflammation, with similar actions. Their receptor mechanisms and downstream pathways are reviewed. They activate several protein kinases in fibroblasts, including the three types of mitogen-activated protein kinase (MAPK), the kinase of the inhibitor of nuclear factor-kappa B (I kappa BK), and the TNF-/IL-1-activated beta-casein kinase. Cultured cells show a broader spectrum of kinase activation by IL-1 than tissues in vivo, suggesting that the receptors connect to more pathways in proliferating cells than in resting differentiated cells. The c-Jun N-terminal kinase (JNK) is strongly activated by IL-1 in tissues. In rabbit liver this is mediated by MAPK kinase 7; the upstream kinase is unidentified. Little is known of downstream MAPK targets in inflammation. Inhibitor experiments suggest that p38MAPK mediates induction of cyclo-oxygenase-2 and metalloproteinases by IL-1, and of TNF, IL-1 and cyclo-oxygenase-2 by endotoxin (in monocytes). p38MAPK is needed for induction of the mRNAs (except IL-1 mRNA).

Decapeptide agonists of human C5a: the relationship between conformation and neutrophil response.

A series of decapeptide analogues corresponding to the C-terminal region of the human C5a anaphylatoxin (C5a65-74) was synthesized with residue substitutions to restrict conformational flexibility in the C-terminal region (residues 71-74). These analogues behaved as full agonists of natural C5a in their ability to induce shape change (polarization) and the release of enzyme (beta-glucuronidase) from human neutrophils (PMNs). There was a significant pharmacological correlation between the polarization and enzyme-release assays, suggesting similarities in PMN responsiveness toward these constrained peptides. Good correlations were also observed between these two PMN responses and spasmogenic activity (smooth muscle contraction of human fetal artery). A structure-function analysis for PMN polarization and enzyme release led to the identification of the following preferred backbone conformations: a twisted, helix-like conformation for residues 65-69, an extended conformation for residues 70-71, and a beta-turn of type V for residues (71)72-74. The existence of a C-terminal, type V beta-turn is supported by the NOE (nuclear Overhauser effect) results of two peptides from this series. These conformational features are reminiscent of those that were shown to correlate with the expression of spasmogenic and platelet aggregatory activities in an earlier investigation (Sanderson, S.D.; et al. J. Med. Chem. 1994, 37, 3171). These results suggest that PMNs and the cells responsible for smooth muscle contraction possess C5a receptors that respond to similar topochemical features presented by the agonist peptide ligand.

Small molecular probes for G-protein-coupled C5a receptors: conformationally constrained antagonists derived from the C terminus of the human plasma protein C5a.

Activation of the human complement system of plasma proteins in response to infection or injury produces a 4-helix bundle glycoprotein (74 amino acids) known as C5a. C5a binds to G-protein-coupled receptors on cell surfaces triggering receptor-ligand internalization, signal transduction, and powerful inflammatory responses. Since excessive levels of C5a are associated with autoimmune and chronic inflammatory disorders, inhibitors of receptor activation may have therapeutic potential. We now report solution structures and receptor-binding and antagonist activities for some of the first small molecule antagonists of C5a derived from its hexapeptide C terminus. The antagonist NMe-Phe-Lys-Pro-D-Cha-Trp-D-Arg-CO2H (1) surprisingly shows an unusually well-defined solution structure as determined by 1H NMR spectroscopy. This is one of the smallest acyclic peptides found to possess a defined solution conformation, which can be explained by the constraining role of intramolecular hydrogen bonding. NOE and coupling constant data, slow deuterium exchange, and a low dependence on temperature for the chemical shift of the D-Cha-NH strongly indicate an inverse gamma turn stabilized by a D-Cha-NH. OC-Lys hydrogen bond. Smaller conformational populations are associated with a hydrogen bond between Trp-NH.OC-Lys, defining a type II beta turn distorted by the inverse gamma turn incorporated within it. An excellent correlation between receptor-affinity and antagonist activity is indicated for a limited set of synthetic peptides. Conversion of the C-terminal carboxylate of 1 to an amide decreases antagonist potency 5-fold, but potency is increased up to 10-fold over 1 if the amide bond is made between the C-terminal carboxylate and a Lys/Orn side chain to form a cyclic analogue. The solution structure of cycle 6 also shows gamma and beta turns; however, the latter occurs in a different position, and there are clear conformational changes in 6 vs 1 that result in enhanced activity. These results indicate that potent C5a antagonists can be developed by targeting site 2 alone of the C5a receptor and define a novel pharmacophore for developing powerful receptor probes or drug candidates.