Characterization of the disease-causing mechanism of KIF3B mutations from ciliopathy patients

The heterodimeric kinesin-2 motor (KIF3A/KIF3B with accessory protein KAP3) drives intraflagellar transport, essential for ciliogenesis and ciliary function. Three point mutations in the KIF3B subunit have recently been linked to disease in humans (E250Q and L523P) and Bengal cats (A334T) (Cogné et al., Am. J. Hum. Genet., 2020, 106, 893-904). Patients display retinal atrophy and, in some cases, other ciliopathy phenotypes. However, the molecular mechanism leading to disease is currently unknown. Here, we used Kif3a -/- ;Kif3b -/- (knockout) 3T3 cells, which cannot make cilia, to characterize these mutations. While reexpression of KIF3B(E250Q) and KIF3B(L523P) did not rescue ciliogenesis, reexpression of wildtype or KIF3B(A334T) restored ciliogenesis to wildtype levels. Fluorescent tagging revealed that the E250Q mutant decorated microtubules and thus is a rigor mutation. The L523P mutation, in the alpha-helical stalk domain, surprisingly did not affect formation of the KIF3A/KIF3B/KAP3 complex but instead impaired motility along microtubules. Lastly, expression of the A334T motor was reduced in comparison to all other motors, and this motor displayed an impaired ability to disperse the Golgi complex when artificially linked to this high-load cargo. In summary, this work uses cell-based assays to elucidate the molecular effects of disease-causing mutations in the KIF3B subunit on the kinesin-2 holoenzyme.

KIF3A tail domain phosphorylation is not required for ciliogenesis in mouse embryonic fibroblasts

Primary cilia are essential signaling organelles that protrude from most cells in the body. Heterodimeric kinesin-2 (KIF3A/KIF3B/KAP3) powers several intracellular transport processes, including intraflagellar transport (IFT), essential for ciliogenesis. A long-standing question is how a motor protein is differentially regulated for specific cargos. Since phosphorylation of the KIF3A tail domain was suggested to regulate the activity of kinesin-2 for ciliogenesis, similarly as for the cytosolic cargo N-Cadherin, we set out to map the phosphosites involved in this regulation. Using well-characterized Kif3a-/-; Kif3b-/- mouse embryonic fibroblasts, we performed ciliogenesis rescue assays with a library of phosphomimetic mutants comprising all predicted phosphosites in the KIF3A tail domain. In contrast to previous reports, we found that KIF3A tail domain phosphorylation is dispensable for ciliogenesis in mammals. Thus, mammalian kinesin-2 is differently regulated for IFT than currently thought, consistent with the idea of differential regulation for ciliary and cytosolic cargo.

Experience With Proximal Median Nerve Entrapment by the Lacertus Fibrosus

BACKGROUND

Unconscious bias of the clinician favors the diagnosis of carpal tunnel syndrome (CTS) in patients with median paresthesia. We hypothesized that more patients in this cohort would be diagnosed with proximal median nerve entrapment (PMNE) by strengthening our cognitive awareness of this alternative diagnosis. We also hypothesized that patients with PMNE may be successfully treated with surgical release of the lacertus fibrosus (LF).

METHODS

In this retrospective study, cases of median nerve decompression at the carpal tunnel and in the proximal forearm for the 2-year periods before and after adopting strategies to mitigate cognitive bias for CTS were enumerated. Patients diagnosed with PMNE and treated by LF release under local anesthesia were evaluated to determine surgical outcome at minimum 2-year follow-up. Primary outcome measures were changes in preoperative median paresthesia and proximal median-innervated muscle strength.

RESULTS

There was a statistically significant increase in PMNE cases identified after our heightened surveillance was initiated (z = 3.433, P < .001). In 10 of 12 cases, the patient had previous ipsilateral open carpal tunnel release (CTR) but experienced recurrent median paresthesia. In 8 cases evaluated an average of 5 years after LF release, there was improvement in median paresthesia and resolution of median-innervated muscle weakness.

CONCLUSIONS

Owing to cognitive bias, some patients with PMNE may be misdiagnosed with CTS. All patients with median paresthesia, particularly those with persistent or recurrent symptoms after CTR, should be assessed for PMNE. Surgical release limited to the LF may be an effective treatment for PMNE.

GFRAL-expressing neurons suppress food intake via aversive pathways

The TGFβ cytokine family member, GDF-15, reduces food intake and body weight and represents a potential treatment for obesity. Because the brainstem-restricted expression pattern of its receptor, GDNF Family Receptor α-like (GFRAL), presents an exciting opportunity to understand mechanisms of action for area postrema neurons in food intake; we generated GfralCre and conditional GfralCreERT mice to visualize and manipulate GFRAL neurons. We found infection or pathophysiologic states (rather than meal ingestion) stimulate GFRAL neurons. TRAP-Seq analysis of GFRAL neurons revealed their expression of a wide range of neurotransmitters and neuropeptides. Artificially activating GfralCre -expressing neurons inhibited feeding, decreased gastric emptying, and promoted a conditioned taste aversion (CTA). GFRAL neurons most strongly innervate the parabrachial nucleus (PBN), where they target CGRP-expressing (CGRPPBN) neurons. Silencing CGRPPBN neurons abrogated the aversive and anorexic effects of GDF-15. These findings suggest that GFRAL neurons link non-meal-associated pathophysiologic signals to suppress nutrient uptake and absorption.

Decreased sensitivity to the anorectic effects of leptin in mice that lack a Pomc-specific neural enhancer

Enhancer redundancy has been postulated to provide a buffer for gene expression against genetic and environmental perturbations. While work in Drosophila has identified functionally overlapping enhancers, work in mammalian models has been limited. Recently, we have identified two partially redundant enhancers, nPE1 and nPE2, that drive proopiomelanocortin gene expression in the hypothalamus. Here we demonstrate that deletion of nPE1 produces mild obesity while knockout of nPE2 has no discernible metabolic phenotypes. Additionally, we show that acute leptin administration has significant effects on nPE1 knockout mice, with food intake and body weight change significantly impacted by peripheral leptin treatment. nPE1 knockout mice became less responsive to leptin treatment over time as percent body weight change increased over 2 week exposure to peripheral leptin. Both Pomc and Agrp mRNA were not differentially affected by chronic leptin treatment however we did see a decrease in Pomc and Agrp mRNA in both nPE1 and nPE2 knockout calorie restricted mice as compared to calorie restricted PBS-treated WT mice. Collectively, these data suggest dynamic regulation of Pomc by nPE1 such that mice with nPE1 knockout become less responsive to the anorectic effects of leptin treatment over time. Our results also support our earlier findings in which nPE2 may only be critical in adult mice that lack nPE1, indicating that these neural enhancers work synergistically to influence metabolism.

Arthroscopic thermal stabilization for distal radioulnar joint instability: 3 to 19 years follow-up

This retrospective study investigated the clinical outcomes of patients treated for chronic distal radioulnar joint instability with arthroscopic thermal annealing of the superficial radioulnar ligaments, ulnar palmar wrist ligaments, and dorsoulnar wrist capsule using a radiofrequency probe. Sixty patients (62 wrists) were treated over an 18-year period. At mean follow-up of 10 years (range 3 to 19), 30 of 33 patients were satisfied with their surgical outcomes. There were statistically significant improvements in ulnar-sided wrist pain on a visual analogue scale and in distal radioulnar joint stability on the dorsopalmar stress test after surgery compared with preoperative status. The modified Mayo Wrist Score and Quick Disabilities of the Arm, Shoulder, and Hand score of the patients were favourable. Early failure occurred in 11 of 62 wrists. Nine of these 11 wrists needed a secondary procedure. We conclude that arthroscopic thermal shrinkage is effective for the majority of the patients with mild to moderate chronic distal radioulnar joint instability in long-term follow-up. Secondary open ligament reconstruction is an option in the case of early failure.Level of evidence: IV.

The utilization of seawater for the hydrolysis of macroalgae and subsequent bioethanol fermentation

A novel seawater-based pretreatment process was developed to improve the hydrolysis yield of brown (Laminaria digitata), green (Ulva linza) and red (Porphyra umbilicalis) macroalgae. Pre-treated with 5% sulphuric acid at 121 °C, 15 minutes, L. digitata, U. linza and P. umbilicalis liberated 64.63 ± 0.30%, 69.19 ± 0.11% and 63.03 ± 0.04% sugar in seawater compared with 52.82 ± 0.16%, 45.93 ± 0.37% and 48.60 ± 0.07% in reverse-osmosis water, respectively. Low hydrolysis yields (2.6-11.7%) were observed in alkali and hydrothermal pretreatment of macroalgae, although seawater led to relatively higher yields. SEM images of hydrolyzed macroalgae showed that reverse-osmosis water caused contortions in the remaining cell walls following acid and hydrothermal pre-treatments in the L. digitata and U. linza samples. Fed-batch fermentations using concentrated green seaweed hydrolysates and seawater with marine yeast Wickerhamomyces anomalus M15 produced 48.24 ± 0.01 g/L ethanol with an overall yield of 0.329 g/g available sugars. Overall, using seawater in hydrolysis of seaweed increased sugar hydrolysis yield and subsequent bioethanol production.

Paraventricular, subparaventricular and periventricular hypothalamic IRS4-expressing neurons are required for normal energy balance

Understanding the neural components modulating feeding-related behavior and energy expenditure is crucial to combating obesity and its comorbidities. Neurons within the paraventricular nucleus of the hypothalamus (PVH) are a key component of the satiety response; activation of the PVH decreases feeding and increases energy expenditure, thereby promoting negative energy balance. In contrast, PVH ablation or silencing in both rodents and humans leads to substantial obesity. Recent studies have identified genetically-defined PVH subpopulations that control discrete aspects of energy balance (e.g. oxytocin (OXT), neuronal nitric oxide synthase 1 (NOS1), melanocortin 4-receptor (MC4R), prodynorphin (PDYN)). We previously demonstrated that non-OXT NOS1^PVH neurons contribute to PVH-mediated feeding suppression. Here, we identify and characterize a non-OXT, non-NOS1 subpopulation of PVH and peri-PVH neurons expressing insulin-receptor substrate 4 (IRS4^PVH) involved in energy balance control. Using Cre-dependent viral tools to activate, trace and silence these neurons, we highlight the sufficiency and necessity of IRS4^PVH neurons in normal feeding and energy expenditure regulation. Furthermore, we demonstrate that IRS4^PVH neurons lie within a complex hypothalamic circuitry that engages distinct hindbrain regions and is innervated by discrete upstream hypothalamic sites. Overall, we reveal a requisite role for IRS4^PVH neurons in PVH-mediated energy balance which raises the possibility of developing novel approaches targeting IRS4^PVH neurons for anti-obesity therapies.

Outcomes of ulnar nerve anterior transmuscular transposition and significance of ulnar nerve instability in cubital tunnel syndrome

BACKGROUND

We investigated the experience of a single surgeon with ulnar nerve anterior transmuscular transposition with the patient in the lateral decubitus position for cubital tunnel syndrome.

METHODS

The medical records of all patients who underwent primary or revision ulnar nerve anterior transmuscular transposition were screened to define a cohort of 156 patients (162 limbs) for further study of demographic and disease-specific data and retrospective assessment of short-term outcomes. Ulnar neuropathy severity was stratified by McGowan grade. A prospective cohort composed of 49 patients (51 limbs) with a minimum 2-year follow-up volunteered to complete patient outcome surveys, and some presented for an ulnar nerve-focused examination to assess long-term outcomes.

RESULTS

The overall patient satisfaction rate was 92%, with statistically significant improvements in ulnar sensation and intrinsic strength at short- and long-term follow-up. Outcomes were better for lower McGowan grades than for higher grades and better in primary cases than in revision cases. Ulnar nerve instability was observed in 69 of 162 cases (43%) in this series. A major complication occurred in 7 cases (4.3%), but all were mitigated by contributory patient-related factors. Reoperation for recurrent ulnar paresthesia was required in 4 cases (2.5%). No operations or outcomes were compromised by the lateral decubitus position.

DISCUSSION AND CONCLUSION

Ulnar nerve anterior transmuscular transposition in the lateral decubitus position is a good surgical option for primary or recurrent cubital tunnel syndrome and remains our preferred procedure. The high prevalence of ulnar nerve instability observed in this study is a factor worthy of consideration by surgeons and patients weighing the surgical options for ulnar neuropathy at the elbow.

Hypothalamic POMC or MC4R deficiency impairs counterregulatory responses to hypoglycemia in mice

Objective

Life-threatening hypoglycemia is a major limiting factor in the management of diabetes. While it is known that counterregulatory responses to hypoglycemia are impaired in diabetes, molecular mechanisms underlying the reduced responses remain unclear. Given the established roles of the hypothalamic proopiomelanocortin (POMC)/melanocortin 4 receptor (MC4R) circuit in regulating sympathetic nervous system (SNS) activity and the SNS in stimulating counterregulatory responses to hypoglycemia, we hypothesized that hypothalamic POMC as well as MC4R, a receptor for POMC derived melanocyte stimulating hormones, is required for normal hypoglycemia counterregulation.

Methods

To test the hypothesis, we induced hypoglycemia or glucopenia in separate cohorts of mice deficient in either POMC or MC4R in the arcuate nucleus (ARC) or the paraventricular nucleus of the hypothalamus (PVH), respectively, and measured their circulating counterregulatory hormones. In addition, we performed a hyperinsulinemic-hypoglycemic clamp study to further validate the function of MC4R in hypoglycemia counterregulation. We also measured Pomc and Mc4r mRNA levels in the ARC and PVH, respectively, in the streptozotocin-induced type 1 diabetes mouse model and non-obese diabetic (NOD) mice to delineate molecular mechanisms by which diabetes deteriorates the defense systems against hypoglycemia. Finally, we treated diabetic mice with the MC4R agonist MTII, administered stereotaxically into the PVH, to determine its potential for restoring the counterregulatory response to hypoglycemia in diabetes.

Results

Stimulation of epinephrine and glucagon release in response to hypoglycemia or glucopenia was diminished in both POMC- and MC4R-deficient mice, relative to their littermate controls. Similarly, the counterregulatory response was impaired in association with decreased hypothalamic Pomc and Mc4r expression in the diabetic mice, a phenotype that was not reversed by insulin treatment which normalized glycemia. In contrast, infusion of an MC4R agonist in the PVH restored the counterregulatory response in diabetic mice.

Conclusion

In conclusion, hypothalamic Pomc as well as Mc4r, both of which are reduced in type 1 diabetic mice, are required for normal counterregulatory responses to hypoglycemia. Therefore, enhancing MC4R function may improve hypoglycemia counterregulation in diabetes.

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Hypothalamic POMC as well as MC4R is necessary to counteract hypoglycemia.

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Type 1 diabetic mice exhibit a reduced Pomc and Mc4r expression in the hypothalamus.

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Insulin treatment does not restore Pomc and Mc4r expression in diabetic mice.

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MC4R agonist improves hypoglycemia counterregulation in diabetic mice.

Colloidal polymer composites: Are nano-fillers always better for improving mechanical properties?

HYPOTHESIS

Colloidal polymer composites, in which polymer particles are blended with a filler, are widely used in applications including pharmaceuticals, crop protection, inks, and protective coatings. It is generally found that the presence of hard particulate fillers will increase the elastic modulus of a polymer colloid composite. However, the influence of the size of the filler particle on the large-strain deformation and fracture and on the viscoelastic characteristics, including creep, is not well explored. We hypothesize that the size ratio of the filler to the colloidal polymer will play a critical role in determining the properties of the composite.

EXPERIMENTS

Colloidal composites were prepared by blending soft polymer colloids (as a binder) with calcium carbonate fillers having four different sizes, spanning from 70 nm to 4.5 μm. There is no bonding between the filler and matrix in the composites. The large-strain deformation, linear viscoelasticity, and creep were determined for each filler size for increasing the filler volume fractions (ϕ_CC). Weibull statistics were used to analyze the distributions of strains at failure.

FINDINGS

We find that the inclusion of nano-fillers leads to brittle fracture at a lower ϕ_CC than when μm-size fillers are used. The data interpretation is supported by Weibull analysis. However, for a given ϕ_CC, the storage modulus is higher in the rubbery regime, and the creep resistance is higher when nanoparticles are used. Using scanning electron microscopy to support our arguments, we show that the properties of colloidal composites are correlated with their microstructure, which can be altered through control of the filler:polymer particle size ratio. Hard nanoparticles pack efficiently around larger particles to provide reinforcement (manifested as a higher storage modulus and greater creep resistance), but they also introduce weak points that lead to brittleness.

Liraglutide Modulates Appetite and Body Weight Through Glucagon-Like Peptide 1 Receptor-Expressing Glutamatergic Neurons

Glucagon-like peptide 1 receptor (GLP-1R) agonists are U.S. Food and Drug Administration-approved weight loss drugs. Despite their widespread use, the sites of action through which GLP-1R agonists (GLP1RAs) affect appetite and body weight are still not fully understood. We determined whether GLP-1Rs in either GABAergic or glutamatergic neurons are necessary for the short- and long-term effects of the GLP1RA liraglutide on food intake, visceral illness, body weight, and neural network activation. We found that mice lacking GLP-1Rs in vGAT-expressing GABAergic neurons responded identically to controls in all parameters measured, whereas deletion of GLP-1Rs in vGlut2-expressing glutamatergic neurons eliminated liraglutide-induced weight loss and visceral illness and severely attenuated its effects on feeding. Concomitantly, deletion of GLP-1Rs from glutamatergic neurons completely abolished the neural network activation observed after liraglutide administration. We conclude that liraglutide activates a dispersed but discrete neural network to mediate its physiological effects and that these effects require GLP-1R expression on glutamatergic but not GABAergic neurons.

Transient shear banding in the nematic dumbbell model of liquid crystalline polymers

In the shear flow of liquid crystalline polymers (LCPs) the nematic director orientation can align with the flow direction for some materials but continuously tumble in others. The nematic dumbbell (ND) model was originally developed to describe the rheology of flow-aligning semiflexible LCPs, and flow-aligning LCPs are the focus in this paper. In the shear flow of monodomain LCPs, it is usually assumed that the spatial distribution of the velocity is uniform. This is in contrast to polymer solutions, where highly nonuniform spatial velocity profiles have been observed in experiments. We analyze the ND model, with an additional gradient term in the constitutive model, using a linear stability analysis. We investigate the separate cases of constant applied shear stress and constant applied shear rate. We find that the ND model has a transient flow instability to the formation of a spatially inhomogeneous flow velocity for certain starting orientations of the director. We calculate the spatially resolved flow profile in both constant applied stress and constant applied shear rate in start up from rest, using a model with one spatial dimension to illustrate the flow behavior of the fluid. For low shear rates flow reversal can be seen as the director realigns with the flow direction, whereas for high shear rates the director reorientation occurs simultaneously across the gap. Experimentally, this inhomogeneous flow is predicted to be observed in flow reversal experiments in LCPs.

Essential Role for Hypothalamic Calcitonin Receptor‒Expressing Neurons in the Control of Food Intake by Leptin

The adipocyte-derived hormone leptin acts via its receptor (LepRb) on central nervous system neurons to communicate the repletion of long-term energy stores, to decrease food intake, and to promote energy expenditure. We generated mice that express Cre recombinase from the calcitonin receptor (Calcr) locus (Calcrcre mice) to study Calcr-expressing LepRb (LepRbCalcr) neurons, which reside predominantly in the arcuate nucleus (ARC). Calcrcre-mediated ablation of LepRb in LepRbCalcrknockout (KO) mice caused hyperphagic obesity. Because LepRb-mediated transcriptional control plays a crucial role in leptin action, we used translating ribosome affinity purification followed by RNA sequencing to define the transcriptome of hypothalamic Calcr neurons, along with its alteration in LepRbCalcrKO mice. We found that ARC LepRbCalcr cells include neuropeptide Y (NPY)/agouti-related peptide (AgRP)/γ-aminobutyric acid (GABA) ("NAG") cells as well as non-NAG cells that are distinct from pro-opiomelanocortin cells. Furthermore, although LepRbCalcrKO mice exhibited dysregulated expression of several genes involved in energy balance, neither the expression of Agrp and Npy nor the activity of NAG cells was altered in vivo. Thus, although direct leptin action via LepRbCalcr cells plays an important role in leptin action, our data also suggest that leptin indirectly, as well as directly, regulates these cells.

Reduced renal sympathetic nerve activity contributes to elevated glycosuria and improved glucose tolerance in hypothalamus-specific Pomc knockout mice

Objective

Hypothalamic arcuate nucleus-specific pro-opiomelanocortin deficient (ArcPomc^−/−) mice exhibit improved glucose tolerance despite massive obesity and insulin resistance. We demonstrated previously that their improved glucose tolerance is due to elevated glycosuria. However, the underlying mechanisms that link glucose reabsorption in the kidney with ArcPomc remain unclear. Given the function of the hypothalamic melanocortin system in controlling sympathetic outflow, we hypothesized that reduced renal sympathetic nerve activity (RSNA) in ArcPomc^−/− mice could explain their elevated glycosuria and consequent enhanced glucose tolerance.

Methods

We measured RSNA by multifiber recording directly from the nerves innervating the kidneys in ArcPomc^−/− mice. To further validate the function of RSNA in glucose reabsorption, we denervated the kidneys of WT and diabetic db/db mice before measuring their glucose tolerance and urine glucose levels. Moreover, we performed western blot and immunohistochemistry to determine kidney GLUT2 and SGLT2 levels in either ArcPomc^−/− mice or the renal-denervated mice.

Results

Consistent with our hypothesis, we found that basal RSNA was decreased in ArcPomc^−/− mice relative to their wild type (WT) littermates. Remarkably, both WT and db/db mice exhibited elevated glycosuria and improved glucose tolerance after renal denervation. The elevated glycosuria in obese ArcPomc^−/−, WT and db/db mice was due to reduced renal GLUT2 levels in the proximal tubules. Overall, we show that renal-denervated WT and diabetic mice recapitulate the phenotype of improved glucose tolerance and elevated glycosuria associated with reduced renal GLUT2 levels observed in obese ArcPomc^−/− mice.

Conclusion

Hence, we conclude that ArcPomc is essential in maintaining basal RSNA and that elevated glycosuria is a possible mechanism to explain improved glucose tolerance after renal denervation in drug resistant hypertensive patients.

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Hypothalamic POMC is essential in maintaining basal renal sympathetic nerve activity.

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Renal denervation improves glucose tolerance in wild-type and db/db mice by elevating their glycosuria.

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Decreased renal GLUT2 is responsible for elevated glycosuria in mice with suppressed renal sympathetic nerve activity.

The effects of Hurricane Sandy on trauma center admissions

BACKGROUND

Hurricane Sandy was a particularly unusual storm with regard to both size and location of landfall. The storm landed in New Jersey, which is unusual for a tropical storm of such scale, and created hazardous conditions which caused injury to residents during the storm and in the months following. This study aims to describe differences in trauma center admissions and patterns of injury during this time period when compared to a period with no such storm.

METHODS

Data were collected for this study from patients who were admitted to the trauma center at Morristown Medical Center during Hurricane Sandy or the ensuing cleanup efforts (patients admitted between 29 October 2012 and 27 December 2012) as well as a control group consisting of all patients admitted to the trauma center between 29 October 2013 and 27 December 2013. Patient information was collected to compare the admissions of the trauma center during the period of the storm and cleanup to the control period.

RESULTS

A total of 419 cases were identified in the storm and cleanup period. 427 were identified for the control. Striking injuries were more common in the storm and cleanup group by 266.7% (p = 0.0107); cuts were more common by 650.8% (p = 0.0044). Medical records indicate that many of these injuries were caused by Hurricane Sandy. Self-inflicted injuries were more common by 301.3% (p = 0.0294). There were no significant differences in the total number of patients, mortality, or injury severity score between the two cohorts.

CONCLUSION

The data we have collected show that the conditions caused by Hurricane Sandy and the following cleanup had a significant effect on injury patterns, with more patients having been injured by being struck by falling or thrown objects, cut while using tools, or causing self-inflicted injuries. These changes, particularly during the cleanup period, are indicative of environmental changes following the storm which increase these risks of injury.

Reprogramming the body weight set point by a reciprocal interaction of hypothalamic leptin sensitivity and Pomc gene expression reverts extreme obesity

Objective

A major challenge for obesity treatment is the maintenance of reduced body weight. Diet-induced obese mice are resistant to achieving normoweight once the obesogenic conditions are reversed, in part because lowered circulating leptin leads to a reduction in metabolic rate and a rebound of hyperphagia that defend the previously elevated body weight set point. Because hypothalamic POMC is a central leptin target, we investigated whether changes in circulating leptin modify Pomc expression to maintain normal energy balance in genetically predisposed obese mice.

Methods

Mice with reversible Pomc silencing in the arcuate nucleus (ArcPomc^−/−) become morbidly obese eating low-fat chow. We measured body composition, food intake, plasma leptin, and leptin sensitivity in ArcPomc^−/− mice weight-matched to littermate controls by calorie restriction, either from weaning or after developing obesity. Pomc was reactivated by tamoxifen-dependent Cre recombinase transgenes. Long acting PASylated leptin was administered to weight-reduced ArcPomc^−/− mice to mimic the super-elevated leptin levels of obese mice.

Results

ArcPomc^−/− mice had increased adiposity and leptin levels shortly after weaning. Despite chronic calorie restriction to achieve normoweight, ArcPomc^−/− mice remained moderately hyperleptinemic and resistant to exogenous leptin's effects to reduce weight and food intake. However, subsequent Pomc reactivation in weight-matched ArcPomc^−/− mice normalized plasma leptin, leptin sensitivity, adiposity, and food intake. In contrast, extreme hyperleptinemia induced by PASylated leptin blocked the full restoration of hypothalamic Pomc expression in calorie restricted ArcPomc^−/− mice, which consequently regained 30% of their lost body weight and attained a metabolic steady state similar to that of tamoxifen treated obese ArcPomc^−/− mice.

Conclusions

Pomc reactivation in previously obese, calorie-restricted ArcPomc^−/− mice normalized energy homeostasis, suggesting that their body weight set point was restored to control levels. In contrast, massively obese and hyperleptinemic ArcPomc^−/− mice or those weight-matched and treated with PASylated leptin to maintain extreme hyperleptinemia prior to Pomc reactivation converged to an intermediate set point relative to lean control and obese ArcPomc^−/− mice. We conclude that restoration of hypothalamic leptin sensitivity and Pomc expression is necessary for obese ArcPomc^−/− mice to achieve and sustain normal metabolic homeostasis; whereas deficits in either parameter set a maladaptive allostatic balance that defends increased adiposity and body weight.

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Hypothalamic POMC-deficiency increases adiposity and induces leptin resistance.

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PASylated leptin blocks the normalization of Pomc expression, weight and adiposity.

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Interactions of leptin sensitivity and Pomc expression dictate body weight set point.

Hypothalamic POMC Deficiency Improves Glucose Tolerance Despite Insulin Resistance by Increasing Glycosuria

Hypothalamic proopiomelanocortin (POMC) is essential for the physiological regulation of energy balance; however, its role in glucose homeostasis remains less clear. We show that hypothalamic arcuate nucleus (Arc)POMC-deficient mice, which develop severe obesity and insulin resistance, unexpectedly exhibit improved glucose tolerance and remain protected from hyperglycemia. To explain these paradoxical phenotypes, we hypothesized that an insulin-independent pathway is responsible for the enhanced glucose tolerance. Indeed, the mutant mice demonstrated increased glucose effectiveness and exaggerated glycosuria relative to wild-type littermate controls at comparable blood glucose concentrations. Central administration of the melanocortin receptor agonist melanotan II in mutant mice reversed alterations in glucose tolerance and glycosuria, whereas, conversely, administration of the antagonist Agouti-related peptide (Agrp) to wild-type mice enhanced glucose tolerance. The glycosuria of ArcPOMC-deficient mice was due to decreased levels of renal GLUT 2 (rGLUT2) but not sodium-glucose cotransporter 2 and was associated with reduced renal catecholamine content. Epinephrine treatment abolished the genotype differences in glucose tolerance and rGLUT2 levels, suggesting that reduced renal sympathetic nervous system (SNS) activity is the underlying mechanism for the observed glycosuria and improved glucose tolerance in ArcPOMC-deficient mice. Therefore, the ArcPOMC-SNS-rGLUT2 axis is potentially an insulin-independent therapeutic target to control diabetes.

Pond sediment magnetite grains show a distinctive microbial community

Formation of magnetite in anaerobic sediments is thought to be enhanced by the activities of iron-reducing bacteria. Geobacter has been implicated as playing a major role, as in culture its cells are often associated with extracellular magnetite grains. We studied the bacterial community associated with magnetite grains in sediment of a freshwater pond in South Korea. Magnetite was isolated from the sediment using a magnet. The magnetite-depleted fraction of sediment was also taken for comparison. DNA was extracted from each set of samples, followed by PCR for 16S bacterial ribosomal RNA (rRNA) gene and HiSeq sequencing. The bacterial communities of the magnetite-enriched and magnetite-depleted fractions were significantly different. The enrichment of three abundant operational taxonomic units (OTUs) suggests that they may either be dependent upon the magnetite grain environment or may be playing a role in magnetite formation. The most abundant OTU in magnetite-enriched fractions was Geobacter, bolstering the case that this genus is important in magnetite formation in natural systems. Other major OTUs strongly associated with the magnetite-enriched fraction, rather than the magnetite-depleted fraction, include a Sulfuricella and a novel member of the Betaproteobacteria. The existence of distinct bacterial communities associated with particular mineral grain types may also be an example of niche separation and coexistence in sediments and soils, which cannot usually be detected due to difficulties in separating and concentrating minerals.

Somatostatin is essential for the sexual dimorphism of GH secretion, corticosteroid-binding globulin production, and corticosterone levels in mice

Distinct male and female patterns of pituitary GH secretion produce sexually differentiated hepatic gene expression profiles, thereby influencing steroid and xenobiotic metabolism. We used a fully automated system to obtain serial nocturnal blood samples every 15 minutes from cannulated wild-type (WT) and somatostatin knockout (Sst-KO) mice to determine the role of SST, the principal inhibitor of GH release, in the generation of sexually dimorphic GH pulsatility. WT males had lower mean and median GH values, less random GH secretory bursts, and longer trough periods between GH pulses than WT females. Each of these parameters was feminized in male Sst-KO mice, whereas female Sst-KO mice had higher GH levels than all other groups, but GH pulsatility was unaffected. We next performed hepatic mRNA profiling with high-density microarrays. Male Sst-KO mice exhibited a globally feminized pattern of GH-dependent mRNA levels, but female Sst-KO mice were largely unaffected. Among the differentially expressed female-predominant genes was Serpina6, which encodes corticosteroid-binding globulin (CBG). Increased CBG was associated with elevated diurnal peak plasma corticosterone in unstressed WT females and both sexes of Sst-KO mice compared with WT males. Sst-KO mice also had exaggerated ACTH and corticosterone responses to acute restraint stress. However, consistent with their lack of phenotypic signs of excess glucocorticoids, cerebrospinal fluid concentrations of free corticosterone in Sst-KO mice were not elevated. In summary, SST is necessary for the prolonged interpulse troughs that define masculinized pituitary GH secretion. SST also contributes to sexual dimorphism of the hypothalamic-pituitary-adrenal axis via GH-dependent regulation of hepatic CBG production.

Functional antagonism between pro-apoptotic BIM and anti-apoptotic BCL-XL in MYC-induced lymphomagenesis

Genomic analyses revealed that many cancers have acquired abnormalities in their expression of pro- or anti-apoptotic members of the BCL-2 protein family. It is, however, unknown whether changes in pro- or anti-apoptotic BCL-2 family members have similar impact on tumorigenesis or whether changes in one subgroup have disproportionate impact. We compared the consequences of concomitant loss of anti-apoptotic Bclx and pro-apoptotic Bim on MYC-induced lymphomagenesis. Whereas only loss of both Bclx alleles markedly forestalled tumorigenesis, loss of a single Bim allele overcame this blockade. Conversely, loss of even a single Bim allele sufficed to substantially accelerate lymphomagenesis, and only loss of both but not loss of a single allele of Bclx could attenuate this acceleration. The evidence that modest (two-fold) monoallelic changes in the expression of at least some BH3-only proteins can profoundly impact tumorigenesis suggests that such aberrations, imposed by epigenetic or genetic changes, may expedite tumorigenesis more effectively than elevated expression of pro-survival BCL-2 family members. These findings further our understanding of the mechanisms of lymphomagenesis and possibly also cancer therapy.

Evidence that increased ovarian aromatase activity and expression account for higher estradiol levels in African American compared with Caucasian women

CONTEXT

Serum estradiol levels are significantly higher across the menstrual cycle in African American (AAW) compared with Caucasian women (CW) in the presence of similar FSH levels, yet the mechanism underlying this disparity is unknown.

OBJECTIVE

The objective of the study was to determine whether higher estradiol levels in AAW are due to increased granulosa cell aromatase mRNA expression and activity.

DESIGN

The design of the study included daily blood sampling and dominant follicle aspirations at an academic medical center during a natural menstrual cycle.

SUBJECTS

Healthy, normal cycling AAW (n = 15) and CW (n = 14) aged 19-34 years participated in the study.

MAIN OUTCOME MEASURES

Hormone levels in peripheral blood and follicular fluid (FF) aspirates and aromatase and FSH receptor mRNA expression in granulosa cells were measured.

RESULTS

AAW had higher FF estradiol [1713.0 (1144.5-2032.5) vs 994.5 (647.3-1426.5) ng/mL; median (interquartile range); P < .001] and estrone [76.9 (36.6-173.4) vs 28.8 (22.5-42.1) ng/mL; P < .001] levels than CW, independent of follicle size. AAW also had lower FF androstenedione to estrone (7 ± 1.8 vs 15.8 ± 4.1; mean ± SE; P = .04) and T to estradiol (0.01 ± 0.002 vs 0.02 ± 0.005; P = .03) ratios, indicating enhanced ovarian aromatase activity. There was a 5-fold increase in granulosa cell aromatase mRNA expression in AAW compared with CW (P < .001) with no difference in expression of FSH receptor. FSH, inhibin A, inhibin B, and AMH levels were not different in AAW and CW.

CONCLUSIONS

Increased ovarian aromatase mRNA expression, higher FF estradiol levels, and decreased FF androgen to estrogen ratios in AAW compared with CW provide compelling evidence that racial differences in ovarian aromatase activity contribute to higher levels of estradiol in AAW across the menstrual cycle. The absence of differences in FSH, FSH receptor expression, and AMH suggest that population-specific genetic variation in CYP19, the gene encoding aromatase, or in factors affecting its expression should be sought.

Numerical study of stretched smectic-A elastomer sheets

We present a numerical study of stretching monodomain smectic-A elastomer sheets, computed using the finite element method. When stretched parallel to their smectic layer normal the smectic layers are unstable to a transition to a buckled state. We model macroscopic deformations by replacing the microscopic energy with a coarse grained effective free energy that accounts for the fine-scale layer buckling. We augment this model with a term to describe the energy of deforming buckled layers, which is necessary to reproduce the experimentally observed Poisson ratios postbuckling. We examine the spatial distribution of the microstructure phases for various stretching angles relative to the layer normal and for different length-to-width aspect ratios. When stretching parallel to the layer normal the majority of the sample forms a bidirectionally buckled microstructure, except at the clamps where a unidirectionally buckled microstructure is predicted. When stretching at small inclinations to the layer normal the phase of the sample is sensitive to the aspect ratio of the sample, with the bidirectionally buckled phase persistent to large angles only for small aspect ratios. We relate these theoretical results to experiments on smectic-A elastomers.

Negative Poisson's ratio and semisoft elasticity of smectic-C liquid-crystal elastomers

Models of smectic-C liquid-crystal elastomers predict that they can display soft elasticity, in which the shape of the elastomer changes at no energy cost. The amplitude of the soft mode and the accompanying shears are dependent on the orientation of the layer normal and the director with respect to the stretch axis. We demonstrate that in some geometries the director is forced to rotate perpendicular to the stretch axis, causing lateral expansion of the sample-a negative Poisson's ratio. Current models do not include the effect of imperfections that must be present in the physical sample. We investigate the effect of a simple model of these imperfections on the soft modes in monodomain smectic-C elastomers in a variety of geometries. When stretching parallel to the layer normal (with imposed strain) the elastomer has a negative stiffness once the director starts to rotate. We show that this is a result of the negative Poisson's ratio in this geometry through a simple scalar model.

Criteria for polycystic ovarian morphology in polycystic ovary syndrome as a function of age

CONCEPT

Ovaries meeting criteria for polycystic ovary morphology during peak reproductive years may no longer meet the criteria with age.

OBJECTIVE

Ovarian volume and follicle number decrease with age in women with polycystic ovary syndrome (PCOS), permitting age-dependent criteria for PCOM.

DESIGN AND SETTING

We conducted longitudinal (7-15 year interval) and cross-sectional studies to examine polycystic ovarian morphology over time at an outpatient clinic and pathology laboratory in a tertiary care hospital.

PATIENTS

Subjects included those with PCOS defined by the National Institutes of Health criteria (n = 11 and 483 for longitudinal and cross-sectional, respectively) and control women with regular menstrual cycles and no hyperandrogenism (n = 15 and 367), age 18-64 yr.

INTERVENTIONS

Subjects underwent an ovarian ultrasound by a single observer.

MAIN OUTCOME MEASURES

Ovarian volume and follicle number were measured and ultrasound findings confirmed by a pathologist in a subset (n = 9).

RESULTS

Ovarian volume (15.2 +/- 7.4 vs. 7.1 +/- 3.7 ml; P < 0.01) and follicle number (12.8 +/- 3.2 vs. 8.1 +/- 3.9; P < 0.05) decreased longitudinally in PCOS and control women (volume 11.6 +/- 4.4 vs. 5.4 +/- 2.2 ml and follicle number 8.3 +/- 1.9 vs. 6.3 +/- 1.8; both P < 0.005). Using cross-sectional data, log ovarian volume and follicle number decreased in both groups, but the decrease in log ovarian volume was less pronounced in women with PCOS than in controls (P < 0.01). A combination of age, log ovarian volume, follicle number, and testosterone distinguished PCOS subjects from controls with a receiver operator characteristic curve area of 0.90.

CONCLUSIONS

Ovarian volume and follicle number decrease with age in women with PCOS and controls necessitating age-based criteria to define polycystic ovarian morphology. It is possible to use these criteria to distinguish PCOS in women over age 40 yr.

Mechanical switching of ferroelectric rubber

At the A to C transition, smectic elastomers have recently been observed to undergo approximately 35% spontaneous shear strains. We first explicitly describe how strains of up to twice this value could be mechanically or electrically induced in Sm-C elastomers by rotation of the director on a cone around the layer normal with an elastic cost dependent on constraints. Second, for typical sample geometries, we give the various microstructures in Sm-C akin to those seen in nematic elastomers under distortions with constraints. It is possible to give explicit results for the nature of the textures. Chiral Sm-C elastomers are ferroelectric. We calculate how the polarization could be mechanically reversed by large, hard, or soft strains of the rubber depending upon sample geometry.

HIF-1: a key mediator in hypoxia

The transcription factor HIF-1 is one of the principal mediators of homeostasis in human tissues exposed to hypoxia. It is implicated in virtually every process of rapid gene expression in response to low oxygen levels. The most common causes of tissue hypoxia are inflammation and/or insufficient circulation or a combination of both. Inflamed tissues and the areas surrounding malignant tumors are characterized by hypoxia and low concentrations of glucose. Serious and generalized inflammation can lead to sepsis and circulatory collapse resulting in acute or chronic tissue hypoxia in various vital organs which induces a rapid homeostatic process in all nucleated cells of affected organs in the human body. Under hypoxic conditions the alpha and beta subunits of HIF-1 make an active heterodimer and drive the transcription of over 60 genes important for cell survival, adaptation, anaerobic metabolism, immune reaction, cytokine production, vascularization and general tissue homeostasis. In addition, HIF-1 plays a key role in the development of physiological systems in fetal and postnatal life. It is also a critical mediator of cancer, lung and cardiovascular diseases. The better understanding of the functions of HIF-1 and the pharmacological modulation of its activity could mean a successful therapeutic approach to these diseases.

Nonmonotonic models are not necessary to obtain shear banding phenomena in entangled polymer solutions

Recent experiments on entangled polymer solutions may indicate a constitutive instability, and have led some to question the validity of existing constitutive models. We use a modern constitutive model, the Rolie-Poly model plus a solvent viscosity, and show that (i) this simple class of models captures instability, (ii) shear banding phenomena is observable for weakly stable fluids in flow geometries with sufficiently inhomogeneous total stress, and (iii) transient phenomena exhibit inhomogeneities similar to shear banding, even for weakly stable fluids.

Role of "cancer stem cells" and cell survival in tumor development and maintenance

One critical issue for cancer biology is the nature of the cells that drive the inexorable growth of malignant tumors. Reports that only rare cell populations within human leukemias seeded leukemia in mice stimulated the now widely embraced hypothesis that only such "cancer stem cells" maintain all tumor growth. However, the mouse microenvironment might instead fail to support the dominant human tumor cell populations. Indeed, on syngeneic transplantation of mouse lymphomas and leukemias, we and other investigators have found that a substantial proportion (>10%) of their cells drive tumor growth. Thus, dominant clones rather than rare cancer stem cells appear to sustain many tumors. Another issue is the role of cell survival in tumorigenesis. Because tumor development can be promoted by the overexpression of prosurvival genes such as bcl-2, we are exploring the role of endogenous Bcl-2-like proteins in lymphomagenesis. The absence of endogenous Bcl-2 in mice expressing an Emu-myc transgene reduced mature B-cell numbers and enhanced their apoptosis, but unexpectedly, lymphoma development was undiminished or even delayed. This suggests that these tumors originate in an earlier cell type, such as the pro-B or pre-B cell, and that the nascent neoplastic clones do not require Bcl-2 but may instead be protected by a Bcl-2 relative.

Smectic-C tilt under shear in smectic-A elastomers

Stenull and Lubensky [Phys. Rev. E 76, 011706 (2007)] have argued that shear strain and tilt of the director relative to the layer normal are coupled in smectic elastomers and that the imposition of one necessarily leads to the development of the other. This means, in particular, that a smectic-A elastomer subjected to a simple shear will develop smectic-C-like tilt of the director. Recently, Kramer and Finkelmann [e-print arXiv:0708.2024; Phys. Rev. E 78, 021704 (2008)], performed shear experiments on smectic-A elastomers using two different shear geometries. One of the experiments, which implements simple shear, produces clear evidence for the development of smectic-C-like tilt. Here, we generalize a model for smectic elastomers introduced by Adams and Warner [Phys. Rev. E 71, 021708 (2005)] and use it to study the magnitude of SmC-like tilt under shear for the two geometries investigated by Kramer and Finkelmann. Using reasonable estimates of model parameters, we estimate the tilt angle for both geometries, and we compare our estimates to the experimental results. The other shear geometry is problematic since it introduces additional in-plane compressions in a sheetlike sample, thus inducing instabilities that we discuss.

Smectic-A elastomers with weak director anchoring

Experimentally it is possible to manipulate the director in a (chiral) smectic- A elastomer using an electric field. This suggests that the director is not necessarily locked to the layer normal, as described in earlier papers that extended rubber elasticity theory to smectics. Here, we consider the case that the director is weakly anchored to the layer normal assuming that there is a free energy penalty associated with relative tilt between the two. We use a recently developed weak-anchoring generalization of rubber elastic approaches to smectic elastomers and study shearing in the plane of the layers, stretching in the plane of the layers, and compression and elongation parallel to the layer normal. We calculate, inter alia, the engineering stress and the tilt angle between director and layer normal as functions of the applied deformation. For the latter three deformations, our results predict the existence of an instability towards the development of shear accompanied by smectic- C-like order.

Mechanical response of smectic-C elastomers

The elastic response of a smectic-C elastomer to three deformations, namely imposed lambda(xx), lambda(xz), and lambda(zz), has been modeled using a nonlinear theory of a nematic elastomer with embedded smectic layers, and with the director tilt (in the x direction) at a fixed angle with respect to the smectic layer normal (z direction). The main focus is the elastic response after any soft mode of the sample. It is found that the elastomer contracts in the x direction under lambda(xz) shear. On stretching parallel to the layer normal it is found that there is a soft mode that acts to rotate the director toward the z direction. The deformation of the system after this soft mode can be reduced to shear and elongation in the plane of the layers. We make predictions of the mechanical response of the elastomer, in particular the length of the soft plateau and the asymptotic modulus for the elastomer when stretched parallel to the layer normal. Finally, since monodomain Sm-C elastomers are made by the deformation-induced alignment of polydomains, we describe these important systems. Qualitative behavior of the model is then compared to existing experimental literature on the mechanical alignment of polydomains.

Lymphoid neoplasia and the control of haemopoietic differentiation

Our broad aims are to delineate oncogenic events in lymphoid neoplasia and to search for genes that control haemopoietic differentiation. To explore lymphoid neoplasia, we have constructed transgenic mice bearing different oncogenes coupled to the immunoglobulin heavy chain enhancer (E mu), to force expression within lymphocytes. The prototype E mu-myc mice are highly prone to lymphomagenesis, generating pre-B and B cell lymphomas. In their pre-neoplastic phase, E mu-myc expression perturbs B cell development, accelerating the accumulation of pre-B cells. Lymphomagenesis requires additional oncogenic events, such as ras activation, and can be reconstructed in vitro. Transgenic mice bearing the N-myc, N-ras, v-abl and bcr-v-abl oncogenes are also prone to tumours. A striking demonstration that oncogenes can perturb lineage commitment has emerged. Introduction of the v-raf gene into cloned E mu-myc transgenic B cells frequently led to a switch in haemopoietic lineage: the cells became macrophages. Two clues to this remarkable metamorphosis are that the macrophage lines produce a myeloid growth factor and most bear marked karyotypic alterations, perhaps indicating that the balance between a few critical lineage control genes has been disturbed. To explore the hypothesis that genes encoding the DNA-binding homeo box domain participate in haemopoiesis, cDNA libraries from haemopoietic sources were screened, and several distinct homeo box cDNAs were isolated. They revealed a complex pattern of expression among haemopoietic cell lines. These genes are attractive candidates for regulators of haemopoietic differentiation.

Stress relaxation in polymer networks: equilibrium behavior and dynamics

The elastic and relaxational properties of a polymer network have been calculated using a stress based formulation based on the Rouse mode expansion [W. L. Vandoolaeghe and E. M. Terentjev, J. Chem. Phys. 123, 34902 (2005)]. In this article, we propose an improved Rouse mode expansion incorporating appropriate boundary conditions. In contrast to the previous work, this improved formulation provides a smooth crossover from the classical equilibrium result of rubber elasticity to the shorter-time-scale Rouse relaxation of a polymer melt. Our results are compared with the classical phantom network approach in equilibrium, as well as both equilibrium and dynamic elongation experiments. The model captures the qualitative features of the data well and some of the quantitative aspects, such as the exponents seen in the dynamic modulus G(omega).

The Bcl-2 apoptotic switch in cancer development and therapy

Impaired apoptosis is both critical in cancer development and a major barrier to effective treatment. In response to diverse intracellular damage signals, including those evoked by cancer therapy, the cell's decision to undergo apoptosis is determined by interactions between three factions of the Bcl-2 protein family. The damage signals are transduced by the diverse 'BH3-only' proteins, distinguished by the BH3 domain used to engage their pro-survival relatives: Bcl-2, Bcl-x(L), Bcl-w, Mcl-1 and A1. This interaction ablates pro-survival function and allows activation of Bax and Bak, which commit the cell to apoptosis by permeabilizing the outer membrane of the mitochondrion. Certain BH3-only proteins (e.g. Bim, Puma) can engage all the pro-survival proteins, but others (e.g. Bad, Noxa) engage only subsets. Activation of Bax and Bak appears to require that the BH3-only proteins engage the multiple pro-survival proteins guarding Bax and Bak, rather than binding to the latter. The balance between the pro-survival proteins and their BH3 ligands regulates tissue homeostasis, and either overexpression of a pro-survival family member or loss of a proapoptotic relative can be oncogenic. Better understanding of the Bcl-2 family is clarifying its role in cancer development, revealing how conventional therapy works and stimulating the search for "BH3 mimetics" as a novel class of anticancer drugs.

Polycystic ovarian morphology in normal women does not predict the development of polycystic ovary syndrome

CONTEXT

Polycystic ovarian morphology (PCOM) is present in 25% of normal women in the absence of polycystic ovary syndrome (PCOS); however, the natural history of PCOM is unknown.

OBJECTIVE

We hypothesized that the presence of PCOM predisposes the development of PCOS.

DESIGN

The study was a longitudinal follow-up study over 8.2 +/- 5.2 yr (mean +/- sd; range 1.7-17.5 yr).

SETTING

The study took place in an outpatient setting.

SUBJECTS

Women who took part in a previous study as a normal control and had an ultrasound examination (n = 40) participated.

INTERVENTION

Subjects underwent an interval menstrual history, physical exam, blood sampling, and repeat ultrasound in the follicular phase.

MAIN OUTCOME MEASURE

Development of PCOS was diagnosed by irregular menses and hyperandrogenism, in the absence of other disorders. Changes in ovarian morphology over time were evaluated.

RESULTS

At the baseline visit, 23 women (57.5%) had PCOM and 17 (42.5%) had normal ovarian morphology. One subject with PCOM developed irregular menses and presumptive PCOS. Eleven subjects with PCOM no longer met the criteria for PCOM at follow-up. There was no factor that predicted the change to normal ovarian morphology at the follow-up visit.

CONCLUSIONS

These data suggest that PCOM in women with regular ovulatory cycles does not commonly predispose the development of PCOS. Although it is unusual to develop PCOM if the ovaries are normal on first assessment, ovaries in women with PCOM no longer meet the criteria for PCOM in approximately half of cases over time.

Subversion of the Bcl-2 life/death switch in cancer development and therapy

The Bcl-2 protein family, which largely determines commitment to apoptosis, has central roles in tumorigenesis and chemoresistance. Its three factions of interacting proteins include the BH3-only proteins (e.g., Bim, Puma, Bad, Noxa), which transduce diverse cytotoxic signals to the mammalian pro-survival proteins (Bcl-2, Bcl-x(L), Bcl-w, Mcl-1, A-1), whereas Bax and Bak, when freed from pro-survival constraint, provoke the mitochondrial permeabilization that triggers apoptosis. We have discovered unexpected specificity in their interactions. Only Bim and Puma, which mediate multiple cytotoxic signals, engage all the pro-survival proteins. Noxa and Bad instead bind subsets and cooperate in killing, indicating that apoptosis requires neutralization of different pro-survival subsets. Furthermore, Mcl-1 and Bcl-x(L), but not Bcl-2, directly sequester Bak in healthy cells, and Bak is freed only when BH3-only proteins neutralize both its guards. BH3-only proteins such as Bim are tumor suppressors and mediate many of the cytotoxic signals from anticancer agents. Hence, compounds mimicking them may prove valuable for therapy. Indeed, the recently described ABT-737 is a promising "BH3 mimetic" of Bad. We find that, like Bad, ABT-737 kills cells efficiently only if Mcl-1 is absent or down-regulated. Thus, manipulation of apoptosis by targeting the Bcl-2 family has exciting potential for cancer treatment.

Structural analysis of a set of proteins resulting from a bacterial genomics project

The targets of the Structural GenomiX (SGX) bacterial genomics project were proteins conserved in multiple prokaryotic organisms with no obvious sequence homolog in the Protein Data Bank of known structures. The outcome of this work was 80 structures, covering 60 unique sequences and 49 different genes. Experimental phase determination from proteins incorporating Se-Met was carried out for 45 structures with most of the remainder solved by molecular replacement using members of the experimentally phased set as search models. An automated tool was developed to deposit these structures in the Protein Data Bank, along with the associated X-ray diffraction data (including refined experimental phases) and experimentally confirmed sequences. BLAST comparisons of the SGX structures with structures that had appeared in the Protein Data Bank over the intervening 3.5 years since the SGX target list had been compiled identified homologs for 49 of the 60 unique sequences represented by the SGX structures. This result indicates that, for bacterial structures that are relatively easy to express, purify, and crystallize, the structural coverage of gene space is proceeding rapidly. More distant sequence-structure relationships between the SGX and PDB structures were investigated using PDB-BLAST and Combinatorial Extension (CE). Only one structure, SufD, has a truly unique topology compared to all folds in the PDB.

Spontaneous shears in smectic elastomers

We model the spontaneous elastic shear deformations of smectic elastomers as they make the thermal transition between the A and C phases. Tilt of the director is accompanied by shear. Unlike nematic elastomers where spontaneous elongation is associated with changes in the magnitude of order, spontaneous distortion in smectics is instead shear and is associated with rotation of the director of the underlying nematic order. The effect of the multistage cross-linking associated with creating monodomain elastomers is taken into account. The angle of molecular tilt and the angle associated with spontaneous shear deformation are not simply related.

Applying e-health to case management

The healthcare industry is only beginning to understand e-health. E-health can be defined as the use of technology to directly improve healthcare delivery-affording patients the opportunity to participate in their own healthcare management, provider, and institution. The market is changing rapidly, and innovations, partnerships, and mergers are taking place daily. For healthcare institutions, setting a long-term, yet adaptable e-health strategy is of vital importance for the continued success of the organization. For clinicians, an understanding of and familiarity with technologies can significantly improve workflow, organization, and patient interaction. For the patient, technology can be leveraged as a means to take initiative and responsibility for his/her own health. This article defines e-health and explains the implications and benefits of e-health to nurses and their patients. The article also identifies unique opportunities e-health/e-commerce can provide case managers in promoting patient connectivity, care management, and economy in cost of care.

The assessment of trust orientation

The development of the Trust Inventory, a 40-item measure of trust in generalized others (Generalized Trust) and romantic partners (Partner Trust) is described. A third conceptualization of trust in friends and family members (Network Trust) is also discussed College students (N = 1,229) participated in five stages of test construction and validation. Results indicated that the Trust Inventory scales are reliable, both internally and temporally, and that the Partner Trust and Generalized Trust Scales demonstrate both concurrent and construct validity. The resulting inventory is unique in its capacity to assess these types of trust simultaneously. Evidence supporting the discriminant validity of the Network Trust was mixed, whereas factor analytic treatments of Trust Inventory items supported the distinctiveness of Network Trust as compared to Partner and Generalized Trust, the Network Trust Scale correlated to roughly the same degree as the other two scales with several variables of differential theoretical relevance. Thus, little evidence supporting the incremental validity of Network Trust was observed Discussion focuses on the evidence suggesting the validity of interpretations of Generalized and Partner Trust and considers the issue of additional research regarding Network Trust.

Soft elasticity in smectic elastomers

We investigate the soft elastic modes of smectic elastomers, that is shape change without energy cost. We use a microscopic model for their nonlinear elasticity, similar to those used for nematic elastomers. We consider two different phases of smectic elastomer; the biaxial smectic A for a simple illustration, and smectic C phases which are of great practical significance. We show that only one nontrivial trajectory of the director gives soft deformations. We give a geometrical interpretation of this soft elastic mode and give an explicit example.

Elasticity of smectic-A elastomers

We present a fully nonlinear model of the elasticity smectic-A elastomers, and compare our results with a wide range of experimental observations: extreme Poisson ratios, the in-plane modulus, the modulus before and after threshold to layer rotation in response to stretches along the layer normal, the threshold strain, the characteristic, and singular rotation of layers after the threshold. We calculate the x-ray scattering from rotating layers and compare with available data. The model is derived in two ways: from geometrical constraints imposed by layers on a nematic elastomer, and from application of statistical mechanics to a microscopic model of the effect of crosslink points confined in a corrugated potential.

Hairpin rubber elasticity

We model the elastic properties of main chain liquid crystalline elastomers, formed by cross linking chains in a strongly nematic state, when they have hairpin defects. We study the response of the elastomer to imposed uniaxial extension along the nematic direction, and employ a microscopic model of how the deformation is distributed non-affinely amongst the hairpin and straight chain populations. The rubber shows a plateau in the stress as a function of the elongation imposed along the director. It is a consequence of the depletion of the actively stretching population of hairpin chains and should not be confused with soft elasticity effects associated with director rotation.

On the polarization of chiral main-chain liquid-crystalline elastomers

A mechanism of developing a polarization in a chiral main-chain liquid-crystalline polymer by aligning the dipoles of the monomers is explored. It is shown that the polarization of a pure liquid crystal elastomer is zero in equilibrium due to rotation of the director in the elastomer. A constraint or specific non-ideality in the elastomer is required to prevent this relaxation of the director in order to realize a non-zero polarization. Three methods that circumvent this result are explored. We consider the effect of an oscillating shear, the pinning effect of the layers in a smectic-A composed of chiral smectogens and a binary mixture of chiral main chains and non-chiral side chains. Each of these methods is shown to produce a polarization, which is much larger than that produced in a piezoelectric alpha-quartz crystal per unit stress.

Bfk: a novel weakly proapoptotic member of the Bcl-2 protein family with a BH3 and a BH2 region

Proteins of the Bcl-2 family are critical regulators of apoptosis. Proapoptotic members, like Bax, contain three of the four Bcl-2 homology regions (BH1-3), while BH3-only proteins, like Bim, possess only the short BH3 motif. Database searches revealed Bfk, an unusual novel member of the Bcl-2 family that contains a BH2 and BH3 region but not BH1 or BH4. Bfk is thus most closely related to Bcl-G(L). It lacks a C-terminal membrane anchor and is cytosolic. Enforced expression of Bfk weakly promoted apoptosis and antagonized Bcl-2's prosurvival function. Like Bcl-G(L), Bfk did not bind to any Bcl-2 family members, even though its BH3 motif can mediate association with prosurvival proteins. Low amounts of Bfk were found in stomach, ovary, bone marrow and spleen, but its level in the mammary gland rose markedly during pregnancy, suggesting that Bfk may play a role in mammary development.

Uncertainties in the role of land vegetation in the carbon cycle

Since the late 1950s the CO2 concentration of the atmosphere has been increasing by around 0.5-3 ppm per year. Understanding of carbon sinks is vital to understanding this trend and its future behaviour. Here we examine some of the factors which may affect the proportion of anthropogenic CO2 ending up in the atmosphere in the present and in the future, and variability in the CO2 increase from one year to another. We also examine the evidence for the potential of terrestrial ecosystem carbon sinks to take up or release CO2. In some cases, a careful re-examination of the research methods used to deduce present and future feedbacks may be necessary. The most advanced technology and the most complex models do not necessarily produce reliable results. They should be carefully checked against a general background knowledge of ecological processes before their results are accepted.