Overnight Dexamethasone Suppression Test: A Reliable Screen for Cushing's Syndrome in the Obese

Objective: Reevaluation of the validity of the 1-mg overnight dexamethasone suppression test (ODST) as a screening test for Cushing's syndrome in obese patients. Research Methods and Procedures: Eighty-six obese patients (body mass index, 30 to 53 kg/m²) that were referred to a general endocrine outpatient clinic for evaluation of simple obesity, diabetes mellitus, hypertension, polycystic ovary disease, or pituitary tumor. One milligram dexamethasone was administered orally at 11:00 pm , and serum cortisol levels were measured the following morning between 8:00 am and 9:00 am . Suppression of serum cortisol to <80 nM (3 μg/dL) was chosen as the cut-off point for normal suppression. Patients with serum cortisol levels ≥80 nM were evaluated for Cushing's syndrome. Results: Suppression of morning cortisol levels to <80 nM occurred in 79 of the 86 obese patients. Seven patients had serum cortisol levels higher than 80 nM; five were eventually diagnosed with Cushing's syndrome and two were considered false positive results in view of normal 24-hour free urinary cortisol and normal suppression on a low dose dexamethasone suppression test (0.5 mg of dexamethasone every 6 hours for 2 days). We found a false positive rate of 2.3% for the ODST using a cut-off serum cortisol of 80 nM. Discussion: The ODST is a valid screening test for Cushing's syndrome in the obese population. The false positive rate was 2.3%, even when using a strict cut-off serum cortisol of 80 nM. Abnormal cortisol suppression in obese patients should be investigated and not be considered false positive results.     

Evaluating Caveolin Interactions: Do Proteins Interact with the Caveolin Scaffolding Domain through a Widespread Aromatic Residue-Rich Motif?

Caveolins are coat proteins of caveolae, small flask-shaped pits of the plasma membranes of most cells. Aside from roles in caveolae formation, caveolins recruit, retain and regulate many caveolae-associated signalling molecules. Caveolin-protein interactions are commonly considered to occur between a ∼20 amino acid region within caveolin, the caveolin scaffolding domain (CSD), and an aromatic-rich caveolin binding motif (CBM) on the binding partner (фXфXXXXф, фXXXXфXXф or фXфXXXXфXXф, where ф is an aromatic and X an unspecified amino acid). The CBM resembles a typical linear motif - a short, simple sequence independently evolved many times in different proteins for a specific function. Here we exploit recent improvements in bioinformatics tools and in our understanding of linear motifs to critically examine the role of CBMs in caveolin interactions. We find that sequences conforming to the CBM occur in 30% of human proteins, but find no evidence for their statistical enrichment in the caveolin interactome. Furthermore, sequence- and structure-based considerations suggest that CBMs do not have characteristics commonly associated with true interaction motifs. Analysis of the relative solvent accessible area of putative CBMs shows that the majority of their aromatic residues are buried within the protein and are thus unlikely to interact directly with caveolin, but may instead be important for protein structural stability. Together, these findings suggest that the canonical CBM may not be a common characteristic of caveolin-target interactions and that interfaces between caveolin and targets may be more structurally diverse than presently appreciated.     

Synthesis and antimalarial and antituberculosis activities of a series of natural and unnatural 4-methoxy-6-styryl-pyran-2-ones, dihydro analogues and photo-dimers

Previous studies have identified the 3,6-dialkyl-4-hydroxy-pyran-2-one marine microbial metabolites pseudopyronines A and B to be modest growth inhibitors of Mycobacterium tuberculosis and a range of tropical diseases including Plasmodium falciparum and Leishmania donovani. In an effort to expand the structure-activity relationship of this compound class towards infectious diseases, a library of natural product and natural product-like 4-methoxy-6-styryl-pyran-2-ones and a subset of catalytically reduced examples were synthesized. In addition, the photochemical reactivity of several of the 4-methoxy-6-styryl-pyran-2-ones were investigated yielding head-to-head and head-to-tail cyclobutane dimers as well as examples of asymmetric aniba-dimer A-type dimers. All compounds were evaluated for cytotoxicity and activity against M. tuberculosis, P. falciparum, L. donovani, Trypanosoma brucei rhodesiense and Trypanosoma cruzi. Of the styryl-pyranones, natural product 3 and non-natural styrene and naphthalene substituted examples 13, 18, 21, 22 and 23 exhibited antimalarial activity (IC(50) <10 μM) with selectivity indices (SI) >10. Δ(7) Dihydro analogues were typically less active or lacked selectivity. Head-to-head and head-to-tail photodimers 5 and 34 exhibited moderate IC(50)s of 2.3 to 17 μM towards several of the parasitic organisms, while the aniba-dimer-type asymmetric dimers 31 and 33 were identified as being moderately active towards P. falciparum (IC(50) 1.5 and 1.7 μM) with good selectivity (SI ~80). The 4-tert-butyl aniba-dimer A analogue 33 also exhibited activity towards L. donovani (IC(50) 4.5 μM), suggesting further elaboration of this latter scaffold could lead to the identification of new leads for the dual treatment of malaria and leishmaniasis.     

Synthesis and structural stability of helichrome as an artificial hemeproteins

A detailed procedure is described for the synthesis of helichrome, which is the first successful example of polypeptide-based artificial hemeprotein. The segment synthesis-condensation approach used for the assembly of small proteins has proven to be extremely useful for protein mimetics as well. The final deprotection was performed using the TMSOTf-thioanisole method instead of the less-convenient hydrogen fluoride method. The unfolding transition of the alpha-helical conformation of helichrome induced by guanidine hydrochloride was studied to understand the stability and dynamics of the folded structure. The resulting parameters (C0.5 = 5.2 M and delta GH2O = -4.4 kcal mol-1) characterizing helichrome denaturation were comparable to that of native globular proteins.     

CD4+Foxp3+ regulatory T cells prolong drug-induced disease remission in (NZBxNZW) F1 lupus mice

Introduction

The ability to ameliorate murine lupus renders regulatory T cells (Treg) a promising tool for the treatment of systemic lupus erythematosus (SLE). In consideration to the clinical translation of a Treg-based immunotherapy of SLE, we explored the potential of CD4+Foxp3+ Treg to maintain disease remission after induction of remission with an established cyclophosphamide (CTX) regimen in lupus-prone (NZBxNZW) F1 mice. As a prerequisite for this combined therapy, we also investigated the impact of CTX on the biology of endogenous Treg and conventional CD4+ T cells (Tcon).

Methods

Remission of disease was induced in diseased (NZBxNZW) F1 mice with an established CTX regimen consisting of a single dose of glucocorticosteroids followed by five day course with daily injections of CTX. Five days after the last CTX injection, differing amounts of purified CD4+Foxp3+CD25+ Treg were adoptively transferred and clinical parameters, autoantibody titers, the survival and changes in peripheral blood lymphocyte subsets were determined at different time points during the study. The influence of CTX on the numbers, frequencies and proliferation of endogenous Treg and Tcon was analyzed in lymphoid organs by flow cytometry.

Results

Apart from abrogating the proliferation of Tcon, we found that treatment with CTX induced also a significant inhibition of Treg proliferation and a decline in Treg numbers in lymphoid organs. Additional adoptive transfer of 1.5 × 10⁶ purified Treg after the CTX regimen significantly increased the survival and prolonged the interval of remission by approximately five weeks compared to mice that received only the CTX regimen. The additional clinical amelioration was associated with an increase in the Treg frequency in the peripheral blood indicating a compensation of CTX-induced Treg deficiency by the Treg transfer.

Conclusions

Treg were capable to prolong the interval of remission induced by conventional cytostatic drugs. This study provides valuable information and a first proof-of-concept for the feasibility of a Treg-based immunotherapy in the maintenance of disease remission in SLE.     

Fragmented living: Behavioural ecology of primates in a forest fragment in the Lopé Reserve, Gabon

A 17-month study was made of the primates using a 9-ha “island” of forest, surrounded by savanna, in the northern part of the Lopé Reserve, Gabon. One group ofCercopithecus cephus (plus a young maleCercopithecus nictitans who was in permanent association with them) were resident in the fragment and groups of five other species of primates made visits during 127 days of observation:Pan troglodytes, 15 visits;Cercocebus albigena, 10;Colobus satanas, 3;Cercopithecus nictitans, 2;C. pogonias, 1. Visits were also made by lone males of three species,C. nictitans, Cercocebus albigena, andMandrillus sphinx. The eighth species of diurnal primate present at Lopé,Gorilla g. gorilla, did not visit the fragment during the study. Compared to conspecific groups in neighbouring continuous forest, primates in the fragment ate less fruit, seeds and flowers and more insects and leaves. The local population density of primates resident in the fragment was equivalent to that of the neighbouring continuous forest where all eight species occur, despite the diversity and abundance of fruit being less in the fragment. The costs imposed on the resident group by the reduced diversity and availability of preferred fruit foods appeared to be offset by a number of benefits that increased individual feeding efficiency for monkeys residing within a single fragment. These included lower travel costs, reduced feeding competition between individuals through group fission, and excellent knowledge of the location and quality of food resources in the small home range. It is also possible that the overall negative impact of inter-specific feeding competition was lower in fragments than in continuous forest and that micro-habitat differences resulted in an increased availability of palatable insect and leaf fallback foods in the fragment.     

Importance of data structure in comparing two dimension reduction methods for classification of microarray gene expression data

Background  

With the advance of microarray technology, several methods for gene classification and prognosis have been already designed. However, under various denominations, some of these methods have similar approaches. This study evaluates the influence of gene expression variance structure on the performance of methods that describe the relationship between gene expression levels and a given phenotype through projection of data onto discriminant axes.     

On the reporting and review requirements of ISO 14044

The International Journal of Life Cycle Assessment -     

The Importance of Mentorship and Interest Group Involvement for the Orthopedic Surgery Applicant

BackgroundMentorship in medical education is important for students’ professional development career planning. Orthopedic Surgery Interest Groups (OSIG) exist as formal organizations and serve as a conduit for undergraduate mentorship, though the role of mentorship via OSIGs within orthopedic medicine has not been thoroughly evaluated. Similarly, OSIGs within institutions are not standardized nor well defined. We sought to answer: (1) What offerings does OSIG provide for students interested in orthopaedic surgery? (2) How does OSIG involvement impact the orthopaedic surgery residency applicant? (3) Does OSIG involvement increase match rates for orthopaedic surgery residency applicants?MethodsAn online survey was distributed to faculty advisors at all allopathic US medical schools with available contact information. Results were analyzed using SPSS.ResultsOf the 28 respondent organizations, the majority (53.6%) have between 1-25 student members. On average, OSIGS offer 3.64 + 1.59 (mode = 4) executive positions. The most important initiative for OSIG groups was clinical/surgical shadowing, followed by faculty mentorship, and guidance for the residency application. OSIG involvement does impact the applicant, as all faculty mentors believed this to be an important component of the residency application. Leadership positions within OSIG was not perceived as being equally important. OSIG involvement did increase match rates; the match rate for all students at the schools surveyed (n=17) was 81.21% while the match rate for students within OSIG (n=17) was 82.39% (p<0.05). Of all students who applied to orthopedic surgery residency programs, 98.9% were members of OSIG, and of all students who successfully matched into orthopedic surgery residency programs in the 2019-2020 cycle, 100% (p<0.05) of students (n=17) were involved in OSIG.ConclusionThis study indicates the importance of involvement in OSIG as a conduit for clinical exposure and mentorship throughout medical education, and is especially relevant for applicants given the impact of the COVID-19 pandemic on the residency application process. Data suggests that participation in an OSIG is a valuable experience for the medical student interested in orthopedics and that students involved in OSIGs are more likely to match into orthopedic residency programs. Level of Evidence: V     

Glucans of lichenized fungi: significance for taxonomy of the genera Parmotrema and Rimelia

The glucans of lichenized fungi are an important class of polysaccharides with structural and chemotaxonomic roles. The water-insoluble glucans of the genus Parmotrema (P. austrosinense, P. delicatulum, P. mantiqueirense, P. schindleri, and P. tinctorum) and those of Rimelia (R. cetrata and R. reticulata), were investigated in order to evaluate the significance in chemotyping, with nigeran [(1-->3),(1-->4)-alpha-glucan] and lichenan [(1-->3),(1-->4)-beta-glucan] characterized using (1)H and (13)C NMR, methylation analysis, and controlled Smith degradations. Results from all species were similar, suggesting that glucan chemistry does not support separation of Rimelia from Parmotrema.