Quest for Universal Health Coverage for Pediatric Acute Lymphoblastic Leukemia in Mexico

PURPOSE

Until 2005, most Mexican children did not have coverage for cancer treatment. In that year, Seguro Popular began funding the treatment of children with acute lymphoblastic leukemia (ALL). We aimed to estimate 5-year survival in children with ALL. We also sought to evaluate the relationship of hospital volume, out-of-state treatment, and treatment administered by an adult hematologist to 5-year survival.

METHODS

We categorized patients according to risk (National Cancer Institute age criteria), hospital volume, out-of-state treatment, and treatment administered by an adult hematologist. We obtained overall 5-year survival using the Kaplan-Meier method and compared survival among groups. We used Cox proportional hazards regression analysis to conduct multivariable analysis and obtained hazard ratios (HRs) and 95% CI.

RESULTS

Between 2005 and 2015, 9,555 children were treated for ALL under Seguro Popular. Mean age (± standard deviation) was 7.4 (4.7) years. Five-year overall survival was 61% (95% CI, 60% to 62%); survival for high-risk patients was 51% (95% CI, 49% to 52%) and 66% (95% CI, 65% to 67%) for those with standard risk. We observed state heterogeneity (Sinaloa: 75% [95% CI, 69% to 80%] v Campeche: 45% [95% CI, 54% to 62%]). Patients who were treated in low-volume hospitals had lower survival rates compared with those treated in medium- and high-volume hospitals (HR v low, 1.17 [95% CI, 1.08 to 1.26]). Patients treated outside of their residence state had 10% lower mortality compared with those treated in their home state (HR, 0.89 [95% CI, 0.82 to 0.99]). The hazard of death among children who were treated by an adult hematologist was 1.93 times (95% CI, 1.44 times to 2.57 times) higher than the hazard of death among those treated by a pediatric oncologist/hematologist (26% [95% CI, 16% to 37%] v 61% [95% CI, 60% to 62%]).

CONCLUSION

Our results highlight the disparities in survival for ALL in Mexico. Health reform must consider increasing the patient volume required for hospital accreditation and mandating treatment by pediatric oncologists/hematologists.

Impact of Therapeutic Interventions on Pain Intensity and Endogenous Pain Modulation in Knee Osteoarthritis: A Systematic Review and Meta-analysis

OBJECTIVE

To study the impact of therapeutic interventions on pain analgesia and endogenous pain modulation in knee osteoarthritis (KOA).

DESIGN

Systematic review and meta-analysis.

METHODS

We searched for KOA randomized clinical trials and observational studies with data on therapeutic interventions comparing pain intensity, temporal summation (TS), and conditioned pain modulation (CPM) scores relative to control. These data were pooled as Hedge's g. To study the relationship between pain intensity and TS/CPM, we performed metaregression with 10,000 Monte-Carlo permutations.

RESULTS

We reviewed 11 studies (559 participants). On studying all the interventions together, we found no significant changes in pain modulation, TS, or CPM. Our findings show that this lack of difference is likely because surgical and nonsurgical interventions resulted in contrary effects. Metaregression significantly correlated pain reduction with normalization of TS and CPM.

CONCLUSIONS

We demonstrate an association between pain reduction and TS/CPM normalization. Though we cannot directly compare these interventions, the results allow us to draw hypotheses on potential practice schemas. Recovering defective endogenous pain modulation mechanisms may help establish long-term analgesia. However, to validate these paradigms as robust clinical biomarkers, further investigation into their mechanisms would be necessary. The registration number for this review is CRD42017072066.

Non-invasive brain stimulation for fine motor improvement after stroke: a meta-analysis

The aim of this study was to determine whether non-invasive brain stimulation (NIBS) techniques improve fine motor performance in stroke. We searched PubMed, EMBASE, Web of Science, SciELO and OpenGrey for randomized clinical trials on NIBS for fine motor performance in stroke patients and healthy participants. We computed Hedges' g for active and sham groups, pooled data as random-effects models and performed sensitivity analysis on chronicity, montage, frequency of stimulation and risk of bias. Twenty-nine studies (351 patients and 152 healthy subjects) were reviewed. Effect sizes in stroke populations for transcranial direct current stimulation and repeated transcranial magnetic stimulation were 0.31 [95% confidence interval (CI), 0.08-0.55; P = 0.010; Tau² , 0.09; I² , 34%; Q, 18.23; P = 0.110] and 0.46 (95% CI, 0.00-0.92; P = 0.05; Tau² , 0.38; I² , 67%; Q, 30.45; P = 0.007). The effect size of non-dominant healthy hemisphere transcranial direct current stimulation on non-dominant hand function was 1.25 (95% CI, 0.09-2.41; P = 0.04; Tau² , 1.26; I² , 93%; Q, 40.27; P < 0.001). Our results show that NIBS is associated with gains in fine motor performance in chronic stroke patients and healthy subjects. This supports the effects of NIBS on motor learning and encourages investigation to optimize their effects in clinical and research settings.

Does non-invasive brain stimulation modify hand dexterity? Protocol for a systematic review and meta-analysis

INTRODUCTION

Dexterity is described as coordinated hand and finger movement for precision tasks. It is essential for day-to-day activities like computer use, writing or buttoning a shirt. Integrity of brain motor networks is crucial to properly execute these fine hand tasks. When these networks are damaged, interventions to enhance recovery are frequently accompanied by unwanted side effects or limited in their effect. Non-invasive brain stimulation (NIBS) are postulated to target affected motor areas and improve hand motor function with few side effects. However, the results across studies vary, and the current literature does not allow us to draw clear conclusions on the use of NIBS to promote hand function recovery. Therefore, we developed a protocol for a systematic review and meta-analysis on the effects of different NIBS technologies on dexterity in diverse populations. This study will potentially help future evidence-based research and guidelines that use these NIBS technologies for recovering hand dexterity.

METHODS AND ANALYSIS

This protocol will compare the effects of active versus sham NIBS on precise hand activity. Records will be obtained by searching relevant databases. Included articles will be randomised clinical trials in adults, testing the therapeutic effects of NIBS on continuous dexterity data. Records will be studied for risk of bias. Narrative and quantitative synthesis will be done.

ETHICS AND DISSEMINATION

No private health information is included; the study is not interventional. Ethical approval is not required. The results will be reported in a peer-review journal.

REGISTRATION DETAILS

PROSPERO International prospective register of systematic reviews registration number: CRD42016043809.

Timing control by redundant inhibitory neuronal circuits

Rhythms and timing control of sequential activity in the brain is fundamental to cognition and behavior. Although experimental and theoretical studies support the understanding that neuronal circuits are intrinsically capable of generating different time intervals, the dynamical origin of the phenomenon of functionally dependent timing control is still unclear. Here, we consider a new mechanism that is related to the multi-neuronal cooperative dynamics in inhibitory brain motifs consisting of a few clusters. It is shown that redundancy and diversity of neurons within each cluster enhances the sensitivity of the timing control with the level of neuronal excitation of the whole network. The generality of the mechanism is shown to work on two different neuronal models: a conductance-based model and a map-based model.

Magnetic field influence on electrical properties of human blood measured by impedance spectroscopy

The impedance spectroscopy technique (IST) was used for studying the effect of a 0.5 T magnetic field on the electrical properties of whole human blood. A Solartron SI 1260 spectrometer was used to measure the impedance spectra of magnetic field exposed blood samples compared to non-exposed samples. An equivalent electrical circuit model, consisting in a resistance Rs in series with a parallel circuit formed by a constant phase element (CPE) and another resistance Rp, is proposed to fit the data in both cases. The experiment used 3 ml human blood samples from 160 healthy donors. A Wilcoxon matched pairs statistical test was applied to the data. The data analysis seems to show a statistically significant increase of the values of resistance Rp (Z = 5.06, P < 0.001) and capacitance CT (Z = 3.32, P < 0.001) of the blood exposed to magnetic field, by approximately 10.4% and 1.9%, respectively.

Explaining synchrony in feed-forward networks: are McCulloch-Pitts neurons good enough?

In any scientific theory, the conceptual framework already determines the nature and possible scope of the results. Oversimplification prevents an adequate description of the system, whereas too detailed a description obscures the fundamental principles behind the observed phenomena in addition to misspending time and resources. In theoretical neuroscience, this is an important issue because the description level varies widely from detailed biophysical descriptions to abstract computational models. We discuss the question of the appropriate modeling level in the context of a recent report on synchrony in iteratively constructed feed-forward networks of rat cortex pyramidal neuron somata (Reyes, 2003).

Lack of association between hyperprolactinemia and soluble IL-2 receptor levels in systemic lupus erythematosus

The aim of the study was to evaluate the association between hyperprolactinemia and T lymphocyte activation through the soluble IL-2 receptor (sIL-2R) in systemic lupus erythematosus (SLE) patients. Seventy SLE patients, 18 of them with hyperprolactinemia (HPRL), were compared with 18 normoprolactinemic (NPRL) patients and 10 age-matched healthy blood-bank donor women. Patients were evaluated by means of the SLE activity index (SLEDAI). Total serum IgG and sIL-2R levels were determined by an ELISA assay. Differences between sIL-2R and IgG serum levels in patients and controls were examined by Kruskal-Wallis analysis and a Spearman r correlation to determine the association between sIL-2R, IgG and prolactin (PRL) levels. IgG and sIL-2R serum levels did not differ significantly between HPRL and NPRL patients: 1827.3 (1428-2226) vs 2028.8 (1586-2467) mg/dl and 882.2 (511-1254) vs 740.1 (534-946.4) U/ml, respectively (confidence interval 95%). In the total SLE group, sIL-2R and IgG serum levels were positively associated (P = 0.0009), however, this was not the case for sIL-2R and PRL (P > 0.49). We did not demonstrate an association between HPRL and lymphocyte activation measured through serum sIL-2R in female patients with SLE.

Biophysical model of synaptic plasticity dynamics

We discuss a biophysical model of synaptic plasticity that provides a unified view of the outcomes of synaptic modification protocols, including: (1) prescribed time courses of postsynaptic intracellular Ca(2+) release, (2) postsynaptic voltage clamping with presentation of presynaptic spike trains at various frequencies, (3) direct postsynaptic response to presynaptic spike trains at various frequencies, and (4) LTP/LTD as a response to precisely timed presynaptic and postsynaptic spikes.

Dynamical synaptic plasticity: a model and connection to some experiments

Using a modified version of a phenomenological model for the dynamics of synaptic plasticity, we examine some recent experiments of Wu et al. [(2001) J Physiol 533:745-755]. We show that the model is quantitatively consistent with their experimental protocols producing long-term potentiation (LTP) and long-term depression (LTD) in slice preparations of rat hippocampus. We also predict the outcome of similar experiments using different frequencies and depolarization levels than reported in their results.

Robustness and enhancement of neural synchronization by activity-dependent coupling

We study the synchronization of two model neurons coupled through a synapse having an activity-dependent strength. Our synapse follows the rules of spike-timing dependent plasticity. We show that this plasticity of the coupling between neurons produces enlarged frequency-locking zones and results in synchronization that is more rapid and much more robust against noise than classical synchronization arising from connections with constant strength. We also present a simple discrete map model that demonstrates the generality of the phenomenon.

Recovery of hidden information through synaptic dynamics

The role of synaptic dynamics in processing neural information is investigated in a neural information channel with realistic model neurons having chaotic intrinsic dynamics. Our neuron models are realized in simple analogue circuits, and our synaptic connections are realized both in analogue circuits and through a dynamic clamp program. The information which is input to the first chaotic neuron in the channel emerges partially absent and partially 'hidden'. Part is absent because of the dynamical effects of the chaotic oscillation that effectively acts as a noisy channel. The 'hidden' part is recoverable. We show that synaptic parameters, most significantly receptor binding time constants, can be tuned to enhance the information transmission by the combination of a neuron plus a synapse. We discuss how the dynamics of the synapse can be used to recover 'hidden' information using average mutual information as a measure of the quality of information transport.

Dynamical model of long-term synaptic plasticity

Long-term synaptic plasticity leading to enhancement in synaptic efficacy (long-term potentiation, LTP) or decrease in synaptic efficacy (long-term depression, LTD) is widely regarded as underlying learning and memory in nervous systems. LTP and LTD at excitatory neuronal synapses are observed to be induced by precise timing of pre- and postsynaptic events. Modification of synaptic transmission in long-term plasticity is a complex process involving many pathways; for example, it is also known that both forms of synaptic plasticity can be induced by various time courses of Ca(2+) introduction into the postsynaptic cell. We present a phenomenological description of a two-component process for synaptic plasticity. Our dynamical model reproduces the spike time-dependent plasticity of excitatory synapses as a function of relative timing between pre- and postsynaptic events, as observed in recent experiments. The model accounts for LTP and LTD when the postsynaptic cell is voltage clamped and depolarized (LTP) or hyperpolarized (LTD) and no postsynaptic action potentials are evoked. We are also able to connect our model with the Bienenstock, Cooper, and Munro rule. We give model predictions for changes in synaptic strength when periodic spike trains of varying frequency and Poisson distributed spike trains with varying average frequency are presented pre- and postsynaptically. When the frequency of spike presentation exceeds approximately 30-40 Hz, only LTP is induced.

Facial and abdominal hair growth in hirsutism: a computerized evaluation

Methods of objectively assessing the growth rate of hairs in hirsute women have generally required some form of shaving and have focused on studying hairs affecting the face, which has reduced the number of patients willing or able to participate in such studies. A possible solution is to assess the terminal hairs on the lower abdomen (ie, the male escutcheon) because these two body areas are the most frequently affected with excess hair growth in hirsute patients. Nonetheless, it is unclear how the growth characteristics (density, diameter, and growth rate) of the hairs on the abdomen and face differ in these patients. We hypothesize that the growth characteristics of terminal hairs on the abdomen and face are similar and that evaluation of either area may be sufficient in assessing the hair growth rate of these patients. To objectively evaluate hair growth in the face and abdomen in hirsute patients, we developed a computer-aided image analysis system capable of measuring several growth parameters. Twenty hirsute women (12 white and 8 black), aged 31.2 +/- 6.1 years, were studied. Facial and abdominal skin areas were shaved, and 3 to 5 days later the areas were photographed through a calibrated glass plate and 5 terminal hairs were plucked from each area. The daily hair growth rate (assessed by photography and by direct measurement of the plucked hair), the density of hairs (number of hairs per surface area assessed by photography), and hair diameter (of the plucked hairs) were determined. The extent of hirsutism was also measured, albeit subjectively, by a modification of the Ferriman-Gallwey method, with each area given a score of 0 (no terminal hairs seen) to 4 (terminal hairs in a pattern similar to that of a very hirsute man). Facial, abdominal, and total Ferriman-Gallwey scores were 1.3 +/- 0.6, 1.8 +/- 0.9, and 12.5 +/- 5.4, respectively. Our results indicated that facial hairs were distributed in greater density and had a greater diameter than abdominal hairs (15.6 +/- 14.2 hairs/cm(2) vs 5.4 +/- 1.9 hairs/cm(2), and 84.5 +/- 19.5 microm and 66.2 +/- 17.5 microm, respectively, P <.005). Alternatively, the growth rates of facial and abdominal hairs were similar, whether determined photographically (0.36 +/- 0.18 mm/day vs 0.43 +/- 0.19 mm/day, respectively) or from plucked hairs (1.2 +/- +0.2 mm/d vs 1.4 + 0.4 mm/d, respectively). We conclude that although the density and diameter of facial hairs are greater than that of lower abdominal hairs, these areas have very similar growth rates. Hence evaluation of either of the body areas, using an objective method of assessing hair growth, should provide equivalent results.

Dynamical encoding by networks of competing neuron groups: winnerless competition

Following studies of olfactory processing in insects and fish, we investigate neural networks whose dynamics in phase space is represented by orbits near the heteroclinic connections between saddle regions (fixed points or limit cycles). These networks encode input information as trajectories along the heteroclinic connections. If there are N neurons in the network, the capacity is approximately e(N-1)!, i.e., much larger than that of most traditional network structures. We show that a small winnerless competition network composed of FitzHugh-Nagumo spiking neurons efficiently transforms input information into a spatiotemporal output.

Connection topology dependence of synchronization of neural assemblies on class 1 and 2 excitability

Two main classes of excitable neurons are analyzed in terms of connection topology and strength of the coupling in a network of neurons. In both cases, we measure the degree of synchronization and responsiveness of the neural assembly. Class 2 excitability presents a fast wave-like propagation of the activity pattern, strong frequency dependence on the connection topology and a good level of synchronization regardless of the topology. On the other hand, class 1 excitability shows a strong dependence of the wave propagation speed and the synchronization degree on the connection topology, in addition no frequency adaptation is observed. We conclude that both types of neural excitability endow the neural assembly with very different dynamical properties. Although, for simplicity reasons, no inhibition has been included in our study, the emergent properties described in this paper may help to determine the class of excitability underlying a neural assembly.

Regularization mechanisms of spiking-bursting neurons

An essential question raised after the observation of highly variable bursting activity in individual neurons of Central Pattern Generators (CPGs) is how an assembly of such cells can cooperatively act to produce regular signals to motor systems. It is well known that some neurons in the lobster stomatogastric ganglion have a highly irregular spiking-bursting behavior when they are synaptically isolated from any connection in the CPG. Experimental recordings show that periodic stimuli on a single neuron can regulate its firing activity. Other evidence demonstrates that specific chemical and/or electrical synapses among neurons also induce the regularization of the rhythms. In this paper we present a modeling study in which a slow subcellular dynamics, the exchange of calcium between an intracellular store and the cytoplasm, is responsible for the origin and control of the irregular spiking-bursting activity. We show this in simulations of single cells under periodic driving and in minimal networks where the cooperative activity can induce regularization. While often neglected in the description of realistic neuron models, subcellular processes with slow dynamics may play an important role in information processing and short-term memory of spiking-bursting neurons.

Model of transient oscillatory synchronization in the locust antennal lobe

Transient pairwise synchronization of locust antennal lobe (AL) projection neurons (PNs) occurs during odor responses. In a Hodgkin-Huxley-type model of the AL, interactions between excitatory PNs and inhibitory local neurons (LNs) created coherent network oscillations during odor stimulation. GABAergic interconnections between LNs led to competition among them such that different groups of LNs oscillated with periodic Ca(2+) spikes during different 50-250 ms temporal epochs, similar to those recorded in vivo. During these epochs, LN-evoked IPSPs caused phase-locked, population oscillations in sets of postsynaptic PNs. The model shows how alternations of the inhibitory drive can temporally encode sensory information in networks of neurons without precisely tuned intrinsic oscillatory properties.

[Infertility treatment before assisted reproductive techniques]

The prevalence of infertility has increased in recent years, but the medical services to treat these problems are not available for most of the affected couples. The prognosis for fertility is important in order to determine the therapeutic capacity of each service, and to select the couples that could be treated at a primary level, or to send them to more advanced levels of reproductive technology. In practice, the infertility is treated in primary medical levels and the assisted reproductive technology is available only to a limited sector of the poblation. In general, the managed-care plans do not compensate directly for infertility treatments, but they are indirectly paying some therapeutic procedures for fertility.

Altered autophosphorylation of the insulin receptor in the ovary of a woman with polycystic ovary syndrome

OBJECTIVE

To determine whether the tyrosine autophosphorylation of the insulin receptor (IR) in the ovary of a woman with polycystic ovary syndrome (PCOS) was reduced compared to normal.

DESIGN

Experimental study.

SETTING

Tertiary care medical center.

PATIENT(S)

One woman with PCOS and one healthy control, both of whom underwent a hysterectomy and bilateral salpingo-oophorectomy.

INTERVENTION(S)

Plasma membrane fraction of ovarian tissue was isolated, and the IR was purified and concentrated.

MAIN OUTCOME MEASURE(S)

Western blots of the IR, which had been incubated with and without insulin, were prepared. Colorimetric and chemiluminescent methods were used to detect the presence of the IR beta-subunit and IR tyrosine autophosphorylation, respectively.

RESULT(S)

The presence of the beta-subunit of the IR was identified in both ovarian samples. The degree of insulin-stimulated IR tyrosine autophosphorylation, reflected by the mean (+/-SD) relative optical density of the 95 kd band, was 4.3-fold higher in the normal ovary compared to the PCOS ovary (0.56 +/- 0.18 optical density vs. 0.13 +/- 0.10 optical density, respectively).

CONCLUSION(S)

Tyrosine autophosphorylation of the IR may be decreased in the ovaries of women with PCOS, similar to the findings in other tissues. The mechanisms through which insulin acts to produce an excess in ovarian androgen production in the face of a decrease in ovarian IR autophosphorylation remain to be determined.

Global dynamics of a network of stochastic neurons maximizes local mutual information

We define a stochastic neuron as an element that increases its internal state with probability p until a threshold value is reached; after that its internal state is set back to the initial value. We study the local information of a stochastic neuron between the message arriving from the input neurons and the response of the neuron. We study the dependence of the local information on the firing probability alpha of the synaptic inputs in a network of such stochastic neurons. The values of alpha obtained in the simulations are the same as those obtained theoretically by maximization of local mutual information. We conclude that the global dynamics maximizes the local mutual information of single units, which means that the self-selected parameter value of the population dynamics is such that each neuron behaves as an optimal encoder.

Topology selection by chaotic neurons of a pyloric central pattern generator

The pyloric Central Pattern Generator (CPG) in the lobster has an architecture in which every neuron receives at least one connection from another member of the CPG. We call this a "non-open" network topology. An "open" topology, where at least one neuron does not receive synapses from any other CPG member, is found neither in the pyloric nor in the gastric mill CPG. Here we investigate a possible reason for this topological structure using the ability to perform a biologically functional task as a measure of the efficacy of the network. When the CPG is composed of model neurons that exhibit regular membrane voltage oscillations, open topologies are as able to maximize this functionality as non-open topologies. When we replace these models by neurons which exhibit chaotic membrane voltage oscillations, the functional criterion selects non-open topologies. As isolated neurons from invertebrate CPGs are known in some cases to undergo chaotic oscillations, this suggests that there is a biological basis for the class of non-open network topologies that we observe.

Dynamical coding of sensory information with competitive networks

Based on experiments with the locust olfactory system, we demonstrate that model sensory neural networks with lateral inhibition can generate stimulus specific identity-temporal patterns in the form of stimulus-dependent switching among small and dynamically changing neural ensembles (each ensemble being a group of synchronized projection neurons). Networks produce this switching mode of dynamical activity when lateral inhibitory connections are strongly non-symmetric. Such coding uses 'winner-less competitive' (WLC) dynamics. In contrast to the well known winner-take-all competitive (WTA) networks and Hopfield nets, winner-less competition represents sensory information dynamically. Such dynamics are reproducible, robust against intrinsic noise and sensitive to changes in the sensory input. We demonstrate the validity of sensory coding with WLC networks using two different formulations of the dynamics, namely the average and spiking dynamics of projection neurons (PN).

Reliable circuits from irregular neurons: a dynamical approach to understanding central pattern generators

Central pattern generating neurons from the lobster stomatogastric ganglion were analyzed using new nonlinear methods. The LP neuron was found to have only four or five degrees of freedom in the isolated condition and displayed chaotic behavior. We show that this chaotic behavior could be regularized by periodic pulses of negative current injected into the neuron or by coupling it to another neuron via inhibitory connections. We used both a modified Hindmarsh-Rose model to simulate the neurons behavior phenomenologically and a more realistic conductance-based model so that the modeling could be linked to the experimental observations. Both models were able to capture the dynamics of the neuron behavior better than previous models. We used the Hindmarsh-Rose model as the basis for building electronic neurons which could then be integrated into the biological circuitry. Such neurons were able to rescue patterns which had been disabled by removing key biological neurons from the circuit.

Adrenocortical hyperresponsivity to adrenocorticotropic hormone: a mechanism favoring the normal production of cortisol in 21-hydroxylase-deficient nonclassic adrenal hyperplasia

OBJECTIVE

To test the hypothesis that patients with nonclassic adrenal hyperplasia (NCAH) exhibit a generalized exaggeration in their response to ACTH stimulation that favors the normal production of F. Patients with 21-hydroxylase (21-OH)-deficient NCAH do not demonstrate cortisol (F) deficiency.

DESIGN

Prospective controlled study.

SETTING

Tertiary university clinic.

PATIENT(S)

Twenty-four untreated patients with NCAH diagnosed by a 17 alpha-hydroxyprogesterone (17-HP) level of >30.3 nmol/L (>10 ng/mL), and 37 age- and body mass-matched healthy eumenorrheic nonhirsute controls.

INTERVENTION(S)

All study subjects underwent a 60 minute acute stimulation using 0.25 mg of ACTH-(1-24) i.v.

MAIN OUTCOME MEASURE(S)

Basal and stimulated serum levels of pregnenolone (PREG), 17-hydroxypregnenolone (17-HPREG), dehydroepiandrosterone (DHA), progesterone (P4), 17-HP, androstenedione (A4), 11-deoxycortisol (S), and cortisol (F).

RESULT(S)

The median basal (i.e., Steroid(0)) or ACTH-stimulated (i. e., Steroid(60)) serum levels of PREG, 17-HPREG, DHA, P4, 17-HP, A4 and, most importantly, S were higher in NCAH patients than in controls. In contrast, the levels of F at either 0 minute or 60 minutes of stimulation were similar between NCAH and control women. The proportion of NCAH patients with stimulated steroids levels of >the 95th percentile of controls were as follows: 84.21% for PREG(60), 87.5% for 17-HPREG(60), 95.8% for DHA(60), 89.5% for P4(60), 100% for 17-HP(60), 91.7% for A4(60), 29.2% for S(60), and 4. 1% for F(60).

CONCLUSION(S)

A generalized adrenocortical hyperresponsivity to ACTH stimulation seems to be present in patients with 21-OH-deficient NCAH, with an exaggerated production of S evident in approximately 30%. The excess production of S in these NCAH patients may, in part, account for their normal F production.

Modeling observed chaotic oscillations in bursting neurons: the role of calcium dynamics and IP3

Chaotic bursting has been recorded in synaptically isolated neurons of the pyloric central pattern generating (CPG) circuit in the lobster stomatogastric ganglion. Conductance-based models of pyloric neurons typically fail to reproduce the observed irregular behavior in either voltage time series or state-space trajectories. Recent suggestions of Chay [Biol Cybern 75: 419-431] indicate that chaotic bursting patterns can be generated by model neurons that couple membrane currents to the nonlinear dynamics of intracellular calcium storage and release. Accordingly, we have built a two-compartment model of a pyloric CPG neuron incorporating previously described membrane conductances together with intracellular Ca2+ dynamics involving the endoplasmic reticulum and the inositol 1,4,5-trisphosphate receptor IP3R. As judged by qualitative inspection and quantitative, nonlinear analysis, the irregular voltage oscillations of the model neuron resemble those seen in the biological neurons. Chaotic bursting arises from the interaction of fast membrane voltage dynamics with slower intracellular Ca2+ dynamics and, hence, depends on the concentration of IP3. Despite the presence of 12 independent dynamical variables, the model neuron bursts chaotically in a subspace characterized by 3-4 active degrees of freedom. The critical aspect of this model is that chaotic oscillations arise when membrane voltage processes are coupled to another slow dynamic. Here we suggest this slow dynamic to be intracellular Ca2+ handling.

Fast response and temporal coherent oscillations in small-world networks

We have investigated the role that different connectivity regimes play in the dynamics of a network of Hodgkin-Huxley neurons by computer simulations. The different connectivity topologies exhibit the following features: random topologies give rise to fast system response yet are unable to produce coherent oscillations in the average activity of the network; on the other hand, regular topologies give rise to coherent oscillations, but in a temporal scale that is not in accordance with fast signal processing. Finally, small-world topologies, which fall between random and regular ones, take advantage of the best features of both, giving rise to fast system response with coherent oscillations.

A central pattern generator to control a pyloric-based system

A central pattern generator (CPG) is built to control a mechanical device (plant) inspired by the pyloric chamber of the lobster. Conductance-based models are used to construct the neurons of the CPG. The plant has an associated function that measures the amount of food flowing through it per unit of time. We search for the best set of solutions that give a high positive flow of food in the maximization function. The plant is symmetric and the model neurons are identical to avoid any bias in the space of solutions. We find that the solution is not unique and that three neurons are sufficient to produce positive flow. We propose an effective principle for CPGs (effective on-off connectivity) and a few predictions to be corroborated in the pyloric system of the lobster.

11beta-hydroxyandrostenedione and delta5-androstenediol as markers of adrenal androgen production in patients with 21-hydroxylase-deficient nonclassic adrenal hyperplasia

OBJECTIVE

To determine the sensitivity of 11beta-hydroxyandrostenedione (11-OHA4) and delta5-androstenediol (ADIOL) as markers of excessive adrenal androgen production.

DESIGN

Prospective study.

SETTING

Academic medical centers.

PATIENT(S)

Thirteen women with untreated 21-hydroxylase-deficient nonclassic adrenal hyperplasia (NCAH) and 18 healthy, eumenorrheic, nonhirsute controls matched for age and body mass index.

INTERVENTION(S)

All subjects were studied before and after acute adrenal stimulation with 0.25 mg of IV ACTH-(1-24).

MAIN OUTCOME MEASURE(S)

Basal levels of total testosterone, sex hormone-binding globulin, DHEAS, and free testosterone were measured. Levels of androstenedione (A4), DHEA, 11-OHA4, and ADIOL were determined before (Steroid0) and 60 minutes after (Steroid60) acute ACTH-(1-24) stimulation.

RESULT(S)

Patients with NCAH had higher median basal levels of DHEAS and total and free testosterone than controls. Patients with NCAH had higher median A4(0), A460, DHEA(0), DHEA60, 11-OHA4(0), ADIOL0, and ADIOL60 levels but similar 11-OHA4(60) levels compared with controls. Among patients with NCAH, 30%, 54%, 15%, and 85% had 11-OHA4(0), ADIOL0, 11-OHA4(60), and ADIOL(60) levels, respectively, above the 95th percentile of controls.

CONCLUSION(S)

Overall, serum levels of 11-OHA4 did not appear to be a very sensitive marker of excessive adrenal androgen production, at least in patients with NCAH. Although ACTH-stimulated ADIOL levels were elevated in 85% of the patients studied, they did not appear to have any advantage over the measurement of A4 or DHEA levels.

Origin of coherent structures in a discrete chaotic medium

Using as an example a large lattice of locally interacting Hindmarsh-Rose chaotic neurons, we disclose the origin of ordered structures in a discrete nonequilibrium medium with fast and slow chaotic oscillations. The origin of the ordering mechanism is related to the appearance of a periodic average dynamics in the group of chaotic neurons whose individual slow activity is significantly synchronized by the group mean field. Introducing the concept of a "coarse grain" as a cluster of neuron elements with periodic averaged behavior allows consideration of the dynamics of a medium composed of these clusters. A study of this medium reveals spatially ordered patterns in the periodic and slow dynamics of the coarse grains that are controlled by the average intensity of the fast chaotic pulsation.

Dynamic control of irregular bursting in an identified neuron of an oscillatory circuit

In the oscillatory circuits known as central pattern generators (CPGs), most synaptic connections are inhibitory. We have assessed the effects of inhibitory synaptic input on the dynamic behavior of a component neuron of the pyloric CPG in the lobster stomatogastric ganglion. Experimental perturbations were applied to the single, lateral pyloric neuron (LP), and the resulting voltage time series were analyzed using an entropy measure obtained from power spectra. When isolated from phasic inhibitory input, LP generates irregular spiking-bursting activity. Each burst begins in a relatively stereotyped manner but then evolves with exponentially increasing variability. Periodic, depolarizing current pulses are poor regulators of this activity, whereas hyperpolarizing pulses exert a strong, frequency-dependent regularizing action. Rhythmic inhibitory inputs from presynaptic pacemaker neurons also regularize the bursting. These inputs 1) reset LP to a similar state at each cycle, 2) extend and further stabilize the initial, quasi-stable phase of its bursts, and 3) at sufficiently high frequencies terminate ongoing bursts before they become unstable. The dynamic time frame for stabilization overlaps the normal frequency range of oscillations of the pyloric CPG. Thus, in this oscillatory circuit, the interaction of rhythmic inhibitory input with intrinsic burst properties affects not only the phasing, but also the dynamic stability of neural activity.

Age at menopause in women with type 2 diabetes mellitus

OBJECTIVE

Considering that chronic diseases such as diabetes mellitus (DM) may determine premature ovarian failure by various mechanisms, we studied the age at menopause in women without diabetes and in women with type 2 DM.

DESIGN

We studied 409 women without diabetes and 404 patients with type 2 DM, selected from 45 to 55 years of age, for analysis with the status quo method. The age at menopause was calculated with a logistic regression on the proportions of menopausal women for each age group.

RESULTS

In the groups, 172 women without diabetes and 207 women with diabetes had menopause. The regression procedure gave a median age of 49.7 +/- SD 1.7 years for the whole group, 49.6 +/- 1.6 years for the nondiabetic group, and 49.8 +/- 1.7 years for women with diabetes. Women without diabetes were 1.4 years younger, but this factor did not have an influence on the results. Smoking habits, vegetarianism, and somatometric variables were similar in both groups, except for waist/hip and abdomen/hip ratios, larger in the group of women with diabetes. The mean for years since diagnosis in patients < 45 years of age was 4.9 years. For older patients, the figure increased to 8.9 years.

CONCLUSIONS

No difference for age at menopause was found between women without diabetes and women with type 2 diabetes who were 5 to 8 years since the diagnosis was made.

Basic principles for generating motor output in the stomatogastric ganglion

The lobster stomatogastric ganglion contains 30 neurons and when modulated can produce two distinct rhythmic motor patterns--the gastric mill and the pyloric. The complete neural circuitry underlying both patterns is well known. Without modulatory input no patterns are produced, and the neurons fire tonically or are silent. When neuromodulators are released into the ganglion from specific neurons or are delivered as hormones, the properties of the neurons and synapses change dramatically and modulator-specific gastric mill and pyloric patterns are produced. In general the rhythmicity derives from the induced burstiness of the neurons, and the pattern from the strengths of the electrical and chemical synapses. The organized activity can be traced to a marked reduction of chaotic activity in individual neurons when they shift from the unmodulated to the modulated state.

High-frequency FSH and LH pulses in obese menopausal women

We studied the pulsatile luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretory patterns, at early or intermediate years of menopause in seven normal women with different degrees of obesity, taking blood samples every minute for 40 min to 2 h. The hormones were assayed with an immunoradiometric assay (IRMA) system, analyzing with the cluster pulse algorithm. All women showed hormone pulses every 8-10 min. In five of them were found periods of discrete pulses with oscillations of high amplitude alternating with periods of pulses of low amplitude. In two cases, the high-frequency oscillatory pattern with low amplitude was found around low mean levels of 22.8 and 25.7 IU/L. The LH oscillatory pattern also had a high frequency, but at a lower level, giving a high FSH/LH ratio. The coincidence index of FSH with LH peaks was 76.6%. We concluded that at menopause, the frequency of FSH and LH secretion increases with a high FSH/LH ratio. Obese menopausal women may have the same high-frequency oscillatory patterns, but at low levels.

Menopause in normal and uncomplicated NIDDM women: physical and emotional symptoms and hormone profile

OBJECTIVE

To compare the physical characteristics, emotional symptoms and metabolic conditions of menopausal women with and without non insulin dependent diabetes mellitus (NIDDM).

METHODS

We studied 100 menopausal women 45-72 years of age, 51 with and 49 without NIDDM, in a cross-sectional design. Biological characteristics were collected and emotional symptoms were assessed with a modified Hamilton and Bech-Rafaelsen scale, scoring depression, anxiety, non specific symptoms of depression (NSSD) and the empty nest syndrome (ENS). Weight, body mass index (BMI), waist/hip and abdomen/hip ratios and percent of body fat were registered. The sulfoconjugated form of the dehydroepiandrosterone (DHEAS), follicle stimulating hormone (FSH), cortisol and fasting, as well as postprandial insulin/glucose ratios, were measured in blood.

RESULTS

Women with NIDDM had earlier mean age for menopause, more central obesity and less peripheral fat; they had also more prevalent emotional symptoms than non diabetic menopausal women. In women with NIDDM, symptoms were associated with years since diagnosis and with BMI. In non diabetic menopausal women schooling and attitudes to sexuality were associated with symptoms. FSH was inversely associated with BMI in both diabetic and non diabetic women; postprandial insulin/glucose ratio was correlated with central obesity in the group without NIDDM and cortisol with sitting systolic blood pressure (SBP) in the group with NIDDM.

CONCLUSION

The diagnosis of NIDDM and its metabolic conditions were associated with an increased frequency of some symptoms in menopausal women.

Negative effects of chemical mutagenesis on the adaptive behavior of vesicular stomatitis virus

Changes in adaptability of vesicular stomatitis virus (VSV) upon treatment with chemical mutagens have been investigated. Results showed no improvement in virus viability or adaptability at any given level of mutagenesis. In fact, increasing inhibition of virus production and adaptability was observed with increasing levels of mutagenesis. This was true for all tested VSV variants replicating either in changing or constant host cell environments. Results also showed that mutagen-treated RNA virus populations which had undergone severe fitness declines were able to recover lost fitness completely after several large-population passages in BHK21, cells. The present findings illustrate the highly optimized states of RNA viruses and their potential to adapt readily. These results are significant for the possible development of specific antiviral agents designed to be mutagenic.

Reproducible nonlinear population dynamics and critical points during replicative competitions of RNA virus quasispecies

RNA virus evolution is generally considered to be highly unpredictable, but tests of determinism in the evolution of competing populations during viral infections have not been performed. Here we study the fate of two closely related evolving quasispecies of vesicular stomatitis virus, by determining the relative concentration of a wild-type clone and a surrogate marked virus subclone (MARM-C) upon extensive competitive replication in a constant cell culture environment. A highly predictable nonlinear behaviour of the two competing populations was found. In addition, the presence of critical points, which are defined as points from which viral competitions may follow different trajectories, has been documented. Critical points were reached after nearly constant periods of time. The dynamics of relative fitness values for both competing populations were calculated during the replication passages. Concomitant with expected fitness gain of both competing viral populations (which follow the Red Queen hypothesis) a tendency for the MARM-C to gain less fitness than the wild-type was observed. Although fitness variations were noisy, this tendency was seen in all evolutionary replicas. Thus, despite the stochastic process of mutation that leads to a continuous generation of mutant genomes during RNA virus replication, a nonlinear, nearly deterministic evolutionary behaviour has been observed. It is proposed that such a behaviour is mediated by a low-pass filter (averaging of mutational noise signals) due to competitive selection among variants.

Synchronized action of synaptically coupled chaotic model neurons

Experimental observations of the intracellular recorded electrical activity in individual neurons show that the temporal behavior is often chaotic. We discuss both our own observations on a cell from the stomatogastric central pattern generator of lobster and earlier observations in other cells. In this paper we work with models with chaotic neurons, building on models by Hindmarsh and Rose for bursting, spiking activity in neurons. The key feature of these simplified models of neurons is the presence of coupled slow and fast subsystems. We analyze the model neurons using the same tools employed in the analysis of our experimental data. We couple two model neurons both electrotonically and electrochemically in inhibitory and excitatory fashions. In each of these cases, we demonstrate that the model neurons can synchronize in phase and out of phase depending on the strength of the coupling. For normal synaptic coupling, we have a time delay between the action of one neuron and the response of the other. We also analyze how the synchronization depends on this delay. A rich spectrum of synchronized behaviors is possible for electrically coupled neurons and for inhibitory coupling between neurons. In synchronous neurons one typically sees chaotic motion of the coupled neurons. Excitatory coupling produces essentially periodic voltage trajectories, which are also synchronized. We display and discuss these synchronized behaviors using two "distance" measures of the synchronization.

Adherence to treatment and social support in patients with non-insulin dependent diabetes mellitus

We carried out a cross-sectional study to investigate factors associated with adherence to diet and medication in non-insulin-dependent diabetes mellitus (NIDDM) patients. A total of 200 patients not seeking treatment from clubs for diabetics from two hospitals in León, Mexico, accepted inclusion. Patients interviewed had a mean age of 58.8 (53.3-56.4, 95% C.I.) years. We evaluated adherence to diet and medication, knowledge on diabetes, social support, family's structure and functioning (with a modified McMaster model), metabolic control, and complications. Stepwise multiple regression procedure showed that adherence to diet was associated with years since diagnosis (p = 0.003) and with social support (p = 0.007). Adherence to medication was associated with social support (p = 0.002), and the age of the spouse (p = 0.016). Adherence to medication was lower in patients from families with rigid control than in the group with Laissez-faire type of control (p = 0.010) or the group with flexible control (p = 0.002). Social support was lower in the group with chaotic control than that in the group with flexible control (p < 0.001). Compliance to diet was associated with peripheral neuropathy and plasma creatinine, and adherence to medication with plasma glucose and peripheral neuropathy. We concluded that (1) adherence to treatment in NIDDM patients is associated with social support; (2) some aspects related to the family, such as the age of the spouse and the control of behavior, were also associated with compliance to treatment; and (3) it is important for the practicing physicians, and for institutional programs, to consider factors associated with adherence to treatment.

Symptoms at perimenopausal period: its association with attitudes toward sexuality, life-style, family function, and FSH levels

We studied the association of symptoms with attitudes toward sexuality, life-style, family functioning, and follicle-stimulating hormone (FSH) levels in perimenopausal women. We collected data on depression, anxiety, nonspecific index of depression, and the empty nest syndrome in 222 women with a mean age of 47.7 (47.2-48.2, 95% CI) years (102 of them were at menopause). Family functioning was evaluated with the McMaster model, and attitudes toward sexuality with questions about women's opinions on sexuality. Scores of depression were higher in women with more than 1 year of menopause. Attitudes to sexuality was significantly associated with all four symptoms. For family function, affective involvement, control of behavior, the roles of the members in the family, and communication were associated with some symptoms. Serum FSH was associated with body mass index, abdomen/hip ratio, and depression. We concluded that: (1) Attitudes toward sexuality was the main regressor for symptoms; (2) the function of the family is also associated with some symptoms; and (3) FSH levels may be lower in obese menopausal women and higher in women with depression or anxiety.

Symptoms at the menopausal and premenopausal years: their relationship with insulin, glucose, cortisol, FSH, prolactin, obesity and attitudes towards sexuality

The symptoms of 81 premenopausal and 70 menopausal women were studied to determine the association with obesity, attitudes towards sexuality (ATS), and diverse hormone values: fasting and postprandial glucose (FG, PG) and insulin (FI, PI), cortisol, prolactin, follicle-stimulating hormone (FSH). The mean age of the women studied was 49.1 years. The frequency of symptoms was 35.4% for depression, 34.3% for nonspecific symptoms of depression (NSSD), 38.6% for empty nest syndrome (ENS), and 42.3% for anxiety. NSSD, ENS, FSH and cortisol levels all possessed higher values at late-menopausal stage. A multiple regression analysis revealed the following results; NSSD was associated to ATS (negative); sleep alterations were correlated to prolactin, FSH, PI/PG, FI/FG and waist/hip ratio; FSH was associated with both a decreased sexual interest and depression. In the study of hormone levels it was found that cortisol, insulin and FI/FG were associated with ATS; PI, cortisol, FI/FG and PI/PG were associated with body mass index (BMI) and FSH; prolactin and FI/FG were associated with age. We concluded that: (1) data indicative of insulin resistance correlated to both depression and sleep alterations; (2) overweight is related to NSSD, sleep alterations, and hormonal changes.