Short-term risk prediction after major lower limb amputation: PERCEIVE study

BACKGROUND

The accuracy with which healthcare professionals (HCPs) and risk prediction tools predict outcomes after major lower limb amputation (MLLA) is uncertain. The aim of this study was to evaluate the accuracy of predicting short-term (30 days after MLLA) mortality, morbidity, and revisional surgery.

METHODS

The PERCEIVE (PrEdiction of Risk and Communication of outcomE following major lower limb amputation: a collaboratIVE) study was launched on 1 October 2020. It was an international multicentre study, including adults undergoing MLLA for complications of peripheral arterial disease and/or diabetes. Preoperative predictions of 30-day mortality, morbidity, and MLLA revision by surgeons and anaesthetists were recorded. Probabilities from relevant risk prediction tools were calculated. Evaluation of accuracy included measures of discrimination, calibration, and overall performance.

RESULTS

Some 537 patients were included. HCPs had acceptable discrimination in predicting mortality (931 predictions; C-statistic 0.758) and MLLA revision (565 predictions; C-statistic 0.756), but were poor at predicting morbidity (980 predictions; C-statistic 0.616). They overpredicted the risk of all outcomes. All except three risk prediction tools had worse discrimination than HCPs for predicting mortality (C-statistics 0.789, 0.774, and 0.773); two of these significantly overestimated the risk compared with HCPs. SORT version 2 (the only tool incorporating HCP predictions) demonstrated better calibration and overall performance (Brier score 0.082) than HCPs. Tools predicting morbidity and MLLA revision had poor discrimination (C-statistics 0.520 and 0.679).

CONCLUSION

Clinicians predicted mortality and MLLA revision well, but predicted morbidity poorly. They overestimated the risk of mortality, morbidity, and MLLA revision. Most short-term risk prediction tools had poorer discrimination or calibration than HCPs. The best method of predicting mortality was a statistical tool that incorporated HCP estimation.

COVID-19: legal implications for critical care

The COVID‐19 pandemic has caused an unprecedented challenge for the provision of critical care. Anticipating an unsustainable burden on the health service, the UK Government introduced numerous legislative measures culminating in the Coronavirus Act, which interfere with existing legislation and rights. However, the existing standards and legal frameworks relevant to critical care clinicians are not extinguished, but anticipated to adapt to a new context. This new context influences the standard of care that can be reasonably provided and yields many human rights considerations, for example, in the use of restraints, or the restrictions placed on patients and visitors under the Infection Prevention and Control guidance. The changing landscape has also highlighted previously unrecognised legal dilemmas. The perceived difficulties in the provision of personal protective equipment for employees pose a legal risk for Trusts and a regulatory risk for clinicians. The spectre of rationing critical care poses a number of legal issues. Notably, the flux between clinical decisions based on best interests towards decisions explicitly based on resource considerations should be underpinned by an authoritative public policy decision to preserve legitimacy and lawfulness. Such a policy should be medically coherent, legally robust and ethically justified. The current crisis poses numerous challenges for clinicians aspiring to remain faithful to medicolegal and human rights principles developed over many decades, especially when such principles could easily be dismissed. However, it is exactly at such times that these principles are needed the most and clinicians play a disproportionate role in safeguarding them for the most vulnerable.

Experimental Demonstration of Hadron Beam Cooling Using Radio-Frequency Accelerated Electron Bunches

Cooling of beams of gold ions using electron bunches accelerated with radio-frequency systems was recently experimentally demonstrated in the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. Such an approach is new and opens the possibility of using this technique at higher energies than possible with electrostatic acceleration of electron beams. The challenges of this approach include generation of electron beams suitable for cooling, delivery of electron bunches of the required quality to the cooling sections without degradation of beam angular divergence and energy spread, achieving the required small angles between electron and ion trajectories in the cooling sections, precise velocity matching between the two beams, high-current operation of the electron accelerator, as well as several physics effects related to bunched-beam cooling. Here we report on the first demonstration of cooling hadron beams using this new approach.

Stress fractures of the foot and ankle

Stress fractures occur as a result of microscopic injuries sustained when bone is subjected to repeated submaximal stresses. Overtime, with repeated cycles of loading, accumulation of such injuries can lead to macro-structural failure and frank fracture. There are numerous stress fractures about the foot and ankle of which a trauma and orthopaedic surgeon should be aware. These include: metatarsal, tibia, calcaneus, navicular, fibula, talus, medial malleolus, sesamoid, cuneiform and cuboid. Awareness of these fractures is important as the diagnosis is frequently missed and appropriate treatment delayed. Late identification can be associated with protracted pain and disability, and may predispose to non-union and therefore necessitate operative intervention. This article outlines the epidemiology and risk factors, aetiology, presentation and management of the range of stress fractures in the foot and ankle.

Design of a high-bunch-charge 112-MHz superconducting RF photoemission electron source

High-bunch-charge photoemission electron-sources operating in a continuous wave (CW) mode are required for many advanced applications of particle accelerators, such as electron coolers for hadron beams, electron-ion colliders, and free-electron lasers. Superconducting RF (SRF) has several advantages over other electron-gun technologies in CW mode as it offers higher acceleration rate and potentially can generate higher bunch charges and average beam currents. A 112 MHz SRF electron photoinjector (gun) was developed at Brookhaven National Laboratory to produce high-brightness and high-bunch-charge bunches for the coherent electron cooling proof-of-principle experiment. The gun utilizes a quarter-wave resonator geometry for assuring beam dynamics and uses high quantum efficiency multi-alkali photocathodes for generating electrons.

161 COMPARISON OF DIFFERENT DIAGNOSTIC METHODS IN EQUINE ENDOMETRITIS

Prolonged endometritis is the most common cause of infertility in mares causing great economic impact. Many mares fail to be diagnosed with endometritis despite the availability of different diagnostic tests. Therefore, the purpose of this study was to compare endometrial swab, low-volume lavage (LVL) and endometrial biopsy as diagnostic methods for endometritis and to report the prevalence of this disease in a referral practice population. Fifty-one mares presenting for routine breeding or infertility work-up were examined by transrectal ultrasonography, before collecting samples for endometrial culture and cytology. Seven of the 51 mares had all the tests except endometrial biopsy. A mare was classified positive for endometritis if she demonstrated two or more of the following 5 criteria on a checklist (new gold standard; NGS): (1) abnormal clinical findings (any of uterine fluid on ultrasound, or excessive oedema for follicular size, or history of subfertility); (2) abnormal gross character of the LVL fluid: (cloudy, discolored, debris) before centrifugation; (3) positive endometrial cytology (≥1 neutrophil per high power field, or ≥1% (1 : 100) neutrophil to epithelial cell ratio on cytology); (4) bacterial growth on culture of the LVL pellet; and (5) histological evidence of inflammation (acute, chronic, and mixed) detected on endometrial biopsy. Data were analysed via kappa coefficient (k) and frequencies were calculated for sensitivity and positive predictive value (PPV) with biopsy being the gold standard and compared to the NGS. Endometritis was diagnosed in 35/44 (79.5%) mares by biopsy (5/35 had acute endometritis, 12/35 had chronic; 18/35 had a combination of acute and chronic endometritis). Based on the endometritis criteria (2/5 items on the checklist), 33/51 (64.7%) mares were diagnosed to have endometritis. All 11 of the barren mares were diagnosed by the checklist, while two of these 11 mares had no evidence of endometritis by biopsy, but had clinical signs or cloudy efflux. The character of the endometrial flush was 45% sensitive (k = 0.046), while culture was 22% sensitive, when compared to endometrial biopsy. When each criterion for endometritis was compared against the NGS, endometrial biopsy was the most sensitive diagnostic method (sensitivity = 86%). Abnormal clinical findings showed moderate agreement with the NGS (k = 0.4138), with a sensitivity of 62% and P = 0.0019. Positive endometrial cytology showed similar agreement (k = 0.3761), and sensitivity (sensitivity = 64%, and P = 0.0069). These studies have also shown the importance of using laboratory data in light of clinical findings, since they have shown that no test by itself is sensitive enough to diagnose a mare with subclinical endometritis, and that this disease might be under diagnosed. Since this study was performed in a referral hospital, there may have been a higher prevalence of endometritis than found in general clinical practice. An endometritis checklist could be used in cases where endometrial biopsies are not readily available.

Designing Endocrine Disruption Out of the Next Generation of Chemicals

A central goal of green chemistry is to avoid hazard in the design of new chemicals. This objective is best achieved when information about a chemical's potential hazardous effects is obtained as early in the design process as feasible. Endocrine disruption is a type of hazard that to date has been inadequately addressed by both industrial and regulatory science. To aid chemists in avoiding this hazard, we propose an endocrine disruption testing protocol for use by chemists in the design of new chemicals. The Tiered Protocol for Endocrine Disruption (TiPED) has been created under the oversight of a scientific advisory committee composed of leading representatives from both green chemistry and the environmental health sciences. TiPED is conceived as a tool for new chemical design, thus it starts with a chemist theoretically at "the drawing board." It consists of five testing tiers ranging from broad in silico evaluation up through specific cell- and whole organism-based assays. To be effective at detecting endocrine disruption, a testing protocol must be able to measure potential hormone-like or hormone-inhibiting effects of chemicals, as well as the many possible interactions and signaling sequellae such chemicals may have with cell-based receptors. Accordingly, we have designed this protocol to broadly interrogate the endocrine system. The proposed protocol will not detect all possible mechanisms of endocrine disruption, because scientific understanding of these phenomena is advancing rapidly. To ensure that the protocol remains current, we have established a plan for incorporating new assays into the protocol as the science advances. In this paper we present the principles that should guide the science of testing new chemicals for endocrine disruption, as well as principles by which to evaluate individual assays for applicability, and laboratories for reliability. In a 'proof-of-principle' test, we ran 6 endocrine disrupting chemicals (EDCs) that act via different endocrinological mechanisms through the protocol using published literature. Each was identified as endocrine active by one or more tiers. We believe that this voluntary testing protocol will be a dynamic tool to facilitate efficient and early identification of potentially problematic chemicals, while ultimately reducing the risks to public health.

Detection and Classification of Movements in Bed using Load Cells

The quality of our life is tied to the quality of our sleep. People with sleep deficits may experience impaired performance, irritability, lack of concentration, and daytime drowsiness. Increased mobility in bed can be a sign of disrupted sleep. Therefore, body movements in bed represent an important behavioral aspect of sleep. In this paper, we propose a method for detection and classification of movement that uses load cells placed at each corner of a bed. The detection of movements is based on short-term analysis of the mean-square differences of the load cell signals. Movement classification is based on features extracted from a wavelet-based tiresolution analysis (MRA) to classify the type of movement into two classes: small and large. A linear classifier is trained on each level of the MRA, and the decisions of the 4 classifiers are combined using a Bayesian combination rule. The method is evaluated on load cell data collected from 6 subjects. Each subject performed 5 trials composed of 20 pre-defined movements including small shifts of position to large movements of torso and limbs. The performance measure for the detection problem is the equal error rate (EER). We show that the detection method achieves a 2.9% EER and that the classification method has a classification error of 4%.

Disordered materials studied using neutron polarization analysis on the multi-detector spectrometer, D7

The technique of longitudinal neutron polarization analysis on a multi-detector neutron spectrometer (so-called `xyz'-polarization analysis) is presented. This technique allows the simultaneous and unambiguous determination of the nuclear, magnetic and nuclear spin-incoherent scattering cross sections as a function of both momentum transfer and energy transfer. The implementation ofxyz-polarization analysis on the recently upgraded D7 spectrometer at the Institut Laue–Langevin in Grenoble is described. Several examples of neutron polarization analysis studies of disordered systems on D7 are given, illustrating the valuable information which can be retrieved from the analysis of neutron diffraction patterns between the Bragg peaks.

The utility of HCC screening among cirrhotics

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Background: Screening known cirrhotics for hepatocellular cancer (HCC) has long been a contentious topic. Studies to date have failed to conclusively prove or disprove the validity of AFP and hepatic ultrasound as screening mechanisms for HCC among cirrhotics, particularly in the American population. It is not clear whether these screening mechanisms provide any benefit in terms of reduced morbidity and mortality. Methods: The study examined all cirrhotics who developed HCC at the Houston Veterans Affairs Medical Center between 1999 and 2005. Those who were screened with AFP and/or imaging (either ultrasound, triphasic liver protocol CT, or MRI) were compared to those patients who were not screened at all. The screened and unscreened patients were compared in terms of Barcelona Clinic Liver Cancer Stage (BCLC) at the time of diagnosis. Results: Statistical analysis revealed a significant difference between the screened and unscreened groups in terms of BCLC stage at diagnosis, with the unscreened group being diagnosed at later stages than the screened group. Of the 155 patients observed, 26 were appropriately screened, and 129 were not. The BCLC stages at diagnosis for the two groups are shown in the table . The different trend in the two groups was found to be statistically significant with a p-value of 0.004. Furthermore, among the screened group, no particular method of screening (AFP vs. imaging vs. combination) was shown to be superior to another. Conclusions: Screening for HCC among cirrhotics using AFP and/or imaging every 6 months does correlate with HCC diagnosis at an earlier BCLC stage, thus portending better treatment options and improved prognosis. Therefore, screening all known cirrhotics for HCC may lead to decreased mortality.

[Table: see text]

No significant financial relationships to disclose.

Talactoferrin alfa may prolong progression-free survival in advanced renal carcinoma patients

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Background: Talactoferrin alfa (formerly known as recombinant human lactoferrin, rhLF) is a novel immunomodulatory 80 kD protein with demonstrated oral anti-tumor properties in animal models, and promising early results in patients with advanced renal cell carcinoma (RCC) in Phase 1/2 trials. Methods: An open label Phase 2 study of Talactoferrin Oral Solution at 1.5 g talactoferrin alfa b.i.d. given up to a maximum of 4 cycles of 12 weeks on, 2 weeks off was conducted at 6 sites. Eligibility included predominantly clear cell histology, failure of at least one prior systemic therapy, tumor progression within the prior 9 months, a performance status of <2 (ECOG) and adequate organ function. The primary endpoints were the incidence of 14-week progression-free survival (PFS) and overall tumor response (by RECIST). The statistical plan specified an objective of 12.5% response rate or a progression-free survival rate of ≥40% at 14 weeks. Secondary endpoints included median PFS and median overall survival (OS). Results: Forty-four patients were enrolled. Eighteen patients (41%) were considered low risk and twenty-six (59%) considered intermediate risk based on the Memorial Sloan-Kettering Cancer Center (MSKCC) criteria. There were no talactoferrin-related Grade 3 or 4 adverse events or laboratory abnormalities. The most common related grade 1 or 2 adverse events were gastrointestinal symptoms. There was one unconfirmed tumor response and the 14-week PFS was 55%. The median PFS was 21 weeks (46 weeks and 9.4 weeks in the patients with low and intermediate risk prognostic factors, respectively). The median OS has not yet been reached. Conclusions: Talactoferrin alfa is well tolerated. The 14-week PFS met the pre-specified criteria for success (>40%). Due to the heterogeneity of tumor biology of RCC, any further evaluation of talactoferrin in this population should be in a larger randomized trial.

[Table: see text]

Challenges and opportunities in the analysis of raffinose oligosaccharides, pentosans, phytate, and glucosinolates

In this paper, the status of the analytical technologies for assaying animal antinutritional compounds, such as raffinose oligosaccharides, pentosans, phytic acid, and glucosinolates, is reviewed in terms of selectivity, sensitivity, and sample throughput. The implementation of simplified sample preparation schemes, use of novel separation approaches, and alternate detector technologies are discussed. The challenges and opportunities posed by these assays are highlighted along with the recommendations for best analytical practices.

Analytical laboratory quality: Part II. Analytical method validation

The most important objective to be met by an analytical testing facility is to have confidence in the data it generates. Most laboratories devote considerable energy to insure that test methods are appropriate, instruments are operational, and the training of analysts is adequate. Experienced scientists will design suitable internal controls in each analysis to confirm the success of a test. Good laboratory managers will monitor the status of facility operations to detect negative trends in the routine performance of instruments, methods, or analysts. Validation, a study designed to insure that a system is suitable for its intended use, is another mechanism that a facility can utilized to enhance confidence that the methods and instruments being used are capable of generating valid results. Additionally, using a validation protocol as a training tool can serve as an excellent manager/mentor mechanism for each type of technology employed in the laboratory. Finally, the generic validation of representative (surrogate) materials allows ongoing assessment of performance attributes independently from the wide variety specific sample types seen by core facilities.

Chromatographic resolution of tryptophan enantiomers with L-Leu-L-Leu-L-Leu peptide effects of mobile phase composition and chromatographic support

Tryptophan enantiomers have been separated by zwitterion pair chromatography using L-leucine-L-leucine-L-leucine peptide as the zwitterion pairing agent. The peptide ligand is adsorbed onto an octadecylsilane support with excess ligand present in bulk solution. This article examines the roles of the hydrophobic matrix and the mobile phase components on tryptophan enantiomer binding and resolution. Capacity factors and enantioselectivites are given for both hydrophobic and hydrophilic matrices using mobile phases containing Leu-Leu-Leu peptide and/or salt. A decrease in selectivity upon the addition of mobile phase salt suggests that quadrupolar ion-pairing contributes to chiral recognition. Results indicate that binding is significantly reduced and separation is not achieved when Leu-Leu-Leu is coupled onto cross-linked or polymerized hydrophilic resins as well as onto macroporous polystyrene resin. However, resin-immobilized Leu-Leu-Asp-Leu-Leu-Leu, Leu-Leu-Glu-Leu-Leu-Leu, and Leu-Leu-Leu-Glu-Leu-Leu peptides, with ion-pairing sites designed to mimic the Leu-Leu-Leu-saturated C18 support, also do not resolve tryptophan enantiomers. This suggests the Leu-Leu-Leu structure is critical for enantiomer resolution. Because D- and L-tryptophan are separated in the absence of bulk Leu-Leu-Leu, chiral discrimination is believed to occur at the surface of the octadecylsilane support.

A negative SimpliRED D-dimer assay result does not exclude the diagnosis of deep vein thrombosis or pulmonary embolus in emergency department patients

STUDY OBJECTIVE

To determine whether a negative SimpliRED D-dimer assay result excludes the diagnosis of deep vein thrombosis (DVT) or pulmonary embolus (PE) in emergency department patients.

METHODS

This prospective, institutional review board-approved, clinical trial enrolled consecutive adult ED patients with the suspected diagnosis of venous thromboembolism (VTE) (DVT or PE). Initial ED evaluation included the SimpliRED D-dimer assay (American Diagnostica Inc, Greenwich, CT). Physicians were blinded to assay results. The diagnosis of DVT was made with positive findings on lower-extremity ultrasonography. PE was confirmed by a high-probability ventilation/perfusion (V/Q) scan, a positive pulmonary angiogram, or a positive finding on lower-extremity ultrasonography. A presumptive diagnosis of VTE was made in patients who had VTE at follow-up or unexplained death during the study period.

RESULTS

One hundred ninety-eight patients were enrolled during the study period. Twenty-five patients were excluded from data analysis; 9 had no diagnostic testing and 16 were lost to follow-up. Of the 173 patients analyzed, 57 (33%) had VTE-16 of 48 evaluated for DVT and 41 of 125 for suspected PE. The SimpliRED assay had a sensitivity of 65% and a negative predictive value of 81% for detection of VTE. In patients evaluated for DVT alone, the sensitivity was 56% and the negative predictive value was 77%. For patients with suspected PE, the sensitivity and negative predictive value were 68% and 83%, respectively.

CONCLUSION

In contrast to earlier reports on the SimpliRED D-dimer assay, a negative result failed to exclude the diagnosis of VTE in our ED population.

Quantification of polycyclic aromatic hydrocarbons in soil at McMurdo Station, Antarctica

Polycyclic aromatic hydrocarbons (PAHs) are a group of compounds that have attracted much attention over the past several years. The United States Environmental Protection Agency (USEPA) has identified numerous PAHs as known or probable human carcinogens. The quantity of PAHs in the environment has dramatically increased, with the majority emitted from fossil fuel combustion sources. Surface soil samples were collected at McMurdo Station, Antarctica (77 degrees 51S, 166 degrees 41E), during peak summer activity and analyzed for PAHs. PAHS were detected at several locations, with maximum concentrations for naphthalene, acenaphthene, acenaphthylene, and fluoranthene at 27,000, 17,800, 15,700 and 13,300 mg/kg, respectively. Results suggest anthropogenic activities may be contributing to increased levels of PAHs present in McMurdo soils.

Arizona hazardous air pollutants monitoring program

In order to evaluate the existing risk to public health in Arizona related to hazardous air pollution, ambient air monitoring for selected hazardous air pollutants (HAPs) was carried out in 1994-1996 in several representative urban and rural areas of Arizona. A wide range of organic HAPs was monitored, requiring a variety of sampling and analysis methods. Stainless steel SUMMA canisters were used for collection of volatile hydrocarbons and halocarbons, which were analyzed by capillary gas chromatography with flame ionization and electron capture detection (GC-FID/ECD). Carbonyl compounds were collected using 2,4-dinitrophenylhydrazine-impregnated cartridges and analyzed by high performance liquid chromatography with ultraviolet detection. Semi-volatile and non-volatile polycyclic aromatic compounds were collected using a sampling train consisting of a filter followed by a PUF/XAD-4/PUF sandwich cartridge. Following extraction, samples were analyzed by capillary GC with mass spectrometric detection (GC-MS). Database software was developed for data processing and reporting functions. This paper describes the sampling strategy and the sampling and analysis methods employed in the monitoring program and presents a summary of all the results obtained during the duration of the sampling program.

Orthopaedic infections

Patients with orthopaedic infections may require admission to the intensive care unit (ICU). Necrotizing fasciitis and clostridial myonecrosis (gas gangrene) are serious soft tissue infections that may cause life-threatening complications. Patients suffering from infectious arthritis, osteomyelitis, or prosthetic joint infections may be seen in the ICU as a result of a previous injury, surgery, or delayed infectious processes. This article introduces the ICU nurse to the pathophysiology, clinical presentation, and management of a variety of orthopaedic infections.

Androgens and masculinization of genitalia in the spotted hyaena (Crocuta crocuta). 1. Urogenital morphology and placental androgen production during fetal life

According to common understanding of sexual differentiation, the formation and development of a penile clitoris in female spotted hyaenas requires the presence of naturally circulating androgens during fetal life. The purpose of the present study was to determine potential source(s) of such fetal androgens by investigating the timing of urogenital development and placental production of androgen during early and mid-gestation. Fetuses determined to be female by molecular techniques (lack of SRY gene) at days 33 and 48 of gestation had undifferentiated gonads, but the clitoris was already 'masculinized' and was generally similar to the phallus of a 50-day-old male fetus. Wolffian and Müllerian ducts terminated at the urogenital sinus in both sexes and a urethra was present along the entire length of the clitoris and penis. The adrenal gland was large and histologically differentiated at 33 days. Steroid gradients across the uterus (a drop in delta 4-androstenedione, with increases in oestrogen and androgen), and high androstenedione in ovarian veins indicated that ovarian androstenedione was metabolized and secreted as testosterone by the placenta throughout gestation. In vitro, whole or homogenized placentae at days 48 and 58 of gestation (110 days total) metabolized radiolabelled androstenedione into testosterone and oestradiol; the specific enzymatic activity of early placental tissues was higher than at later stages. A human placental homogenate had higher aromatase activity but did not produce testosterone unless aromatase was inhibited. Infusion of labelled androstenedione into the uterine arteries of hyaenas demonstrated the conversion of this substrate into testosterone and oestradiol and their secretion into the fetal circulation. Evidently, androgen is produced by the placenta and secreted into the fetal circulation from early in pregnancy when masculinization is first evident, before differentiation of the fetal ovary.

The Telemedicine Information Exchange (TIE)

An on-line information service, the Telemedicine Information Exchange (TIE), was established to provide a comprehensive source of telemedicine information. The TIE comprised a number of frequently updated, searchable, linked databases, each dealing with an important aspect of telemedicine. These included an extensive bibliography on telemedicine consisting of more than 2000 citations, many with abstracts. There was also a series of topical sections describing current telemedicine projects, products and services, legislation, funding, research activities, and news in the field. The TIE was designed to exploit the features of electronic information storage: hypertext linking between related pieces of information; specialized views (technical, legal, and business) of the bibliographic database; and usage monitoring to determine which data were most frequently accessed and therefore where any enhancement should be done. The TIE was made available via the World Wide Web, by remote telnet access over the Internet, and via modern. The rapid increase in the usage of the TIE since its introduction in April 1995 indicated that the TIE satisfied a need in the telemedicine community.

A neurohormone regulating both methyl farnesoate synthesis and glucose metabolism in a crustacean

Methyl farnesoate (MF) has been identified as a juvenile hormone-like compound in crustacea which has central roles in the regulation of development and reproduction. To study the regulation of MF synthesis, we isolated a neuropeptide which inhibits MF synthesis from the neurohemal organ-sinus gland X-organ complex of the spider crab Libinia emarginata. The primary structure of this neuropeptide has been determined. It has 72 amino acid residues (deduced molecular mass 8490.5 Da) with pyroglutamic acid at the N-terminus and NH3 at the C-terminus. It shares a high percentage of sequence identity with other sinus gland neuropeptids which form the unique family of CHH neuropeptides of crustacea. Activity studies showed that this neurohormone has dual effects: it inhibited MF synthesis in vitro and had hyperglycemic activity when injected into crabs.

Leucokinin increases paracellular permeability in insect Malpighian tubules

There are two major transport pathways across epithelia: a transcellular pathway through cells and a paracellular pathway between cells. Previous electrophysiological studies in mosquito Malpighian tubules suggested that the neuropeptide leucokinin-VIII (LK-VIII) increases the chloride permeability of the paracellular pathway. To test the effect of LK-VIII on the paracellular pathway further, we measured transepithelial permeabilities of inulin and sucrose in isolated Malpighian tubules from the mosquito Aedes aegypti. Cell membranes are impermeable to inulin and sucrose, leaving the paracellular pathway as the only route for their transepithelial permeation. LK-VIII (10(-6) mol l-1) significantly increased transepithelial permeability to both inulin (by 73.8 %) and sucrose (by 32.4 %) in parallel with a significant increase in rates of transepithelial fluid secretion (by 75&shy;90 %). Cyclic adenosine monophosphate (cyclic AMP, 10(-4) mol l-1), which is known to stimulate transcellular transport, also increased rates of transepithelial fluid secretion (by 57&shy;59 %), but it did so without increasing the permeability to sucrose and inulin. Thus, LK-VIII increases the permeability of the paracellular pathway whereas cyclic AMP does not.

Allele-specific hybridization of lipoprotein lipase and factor-V Leiden missense mutations with direct label alkaline phosphatase-conjugated oligonucleotide probes

Direct label alkaline phosphatase (AP) conjugated oligonucleotide probes (AP-DNA) were prepared to assess their utility for allele-specific detection of single base substitutions. Oligonucleotide conjugates were designed to detect point mutations in the genes for lipoprotein lipase (LPL) and coagulation factor-V (FV). Genomic DNA samples, including ones known to harbor point mutations in the genes for LPL and FV, were prepared from whole blood and subjected to polymerase chain reaction (PCR). PCR products were analyzed by Southern hybridization with the allele-specific AP-DNA probes and restriction endonuclease analysis. Thermal profiles for hybridization indicate optimal allele-specific selectivity was achieved with temperatures ranging from 45 degrees C to 55 degrees C at a total Na divided by concentration of 150 mM. Under these conditions the base changes studied were easily discriminated with allele specific hybridization signals in excess of 200:1 as estimated by scanning densitometry. Complete concordance was observed between hybridization and restriction analyses for 175 LPL and 201 FV clinical and reference samples. The total time for analysis of the PCR products was less than 2 h with a dot blot hybridization protocol.

Two novel thioesterases are key determinants of the bimodal distribution of acyl chain length of Cuphea palustris seed oil

The seed oil of Cuphea palustris has an unusual fatty-acyl composition, whereby the principal fatty-acyl groups, myristate (64%) and caprylate (20%), differ by more than two methylenes. We have isolated two thioesterase (TE) cDNAs from C. palustris, encoding proteins designated Cp FatB1 and Cp FatB2, which, when expressed in Escherichia coli, have TE activities specific for 8:0/10:0- and 14:0/16:0-acyl carrier protein substrates, respectively. The specific activities of the recombinant affinity-purified enzymes indicate that Cp FatB2 is kinetically superior to Cp FatB1. This result is consistent with the predominance of 14:0 in the seed oil, despite apparently equal mRNA abundance of the two transcripts in the seed. In C. palustris the expression of both sequences is confined to the seed tissues. Based on these findings we propose that these two enzymes are major factors determining the bimodal chain-length composition of C. palustris oil. Analysis of the immature and mature seed oil by reverse-phase high-performance liquid chromatography confirmed that the principal triglycerides contain both 8:0 and 14:0. This result indicates that both fatty acids are synthesized at the same time and in the same cells at all developmental stages during oil deposition, suggesting that the two TEs act together in the same fatty acid synthesis system.